Anomalies in the low CMB multipoles and extended foregrounds

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Size Anomalies in U.S. Bank Stock Returns

THE JOURNAL OF FINANCE•VOL.LXX,NO.2•APRIL2015Size Anomalies in U.S.Bank Stock ReturnsPRIYANK GANDHI and HANNO LUSTIG∗ABSTRACTThe largest commercial bank stocks,ranked by total size of the balance sheet,havesigniﬁcantly lower risk-adjusted returns than small-and medium-sized bank stocks,even though large banks are signiﬁcantly more levered.We uncover a size factor in thecomponent of bank returns that is orthogonal to the standard risk factors,includingsmall minus big,which has the right covariance with bank returns to explain theaverage risk-adjusted returns.This factor measures size-dependent exposure to bank-speciﬁc tail risk.Theseﬁndings are consistent with government guarantees thatprotect shareholders of large banks,but not small banks,in disaster states.B ANKS ARE DIFFERENT FROM NONFINANCIAL FIRMS in many ways.One of the most salient distinctions is that banks are subject to bank runs during banking panics and crises,not just by depositors,but also by other creditors(see Gor-ton and Metrick(2012)and Dufﬁe(2010)).Becauseﬁnancial crises are high marginal utility states for the average investor,the expected return on bank stocks should be especially sensitive to variation in the anticipatedﬁnancial disaster recovery rates of bank shareholders related to bank size,the regu-latory regime,implicit government guarantees,and other characteristics.For example,if a bank is deemed too big to fail,the expected return on its stock is lower in equilibrium than that of smaller banks holding the exact same assets in their portfolio because the government absorbs some of the large bank’s tail risk.Weﬁnd evidence that the pricing of bank-speciﬁc tail risk in the stock market depends on all of these bank characteristics.To explore the asset pricing implications ofﬁnancial disasters,our paper studies historical bank stock returns in the United States.Weﬁnd that there∗Gandhi is with Mendoza College of Business,University of Notre Dame and Lustig is with Anderson School of Management,University of California at Los Angeles.The authors thank the Editors,Cam Harvey and Ken Singleton,as well as the Associate Editor and several referees for excellent suggestions.The authors also thank Viral Acharya,Martin Bodenstein,Markus Brun-nermeier,John Campbell,John Cochrane,Ron Feldman,Cesare Fracassi,Etienne Gagnon,Mark Garmaise,Amit Goyal,Mark Grinblatt,Jennifer Huang,John Krainer,Arvind Krishnamurthy, David Laibson,Jonathan Parker,Lasse Pedersen,Andrea Raffo,Richard Roll,Jan Schneider, Martin Schneider,Clemens Sialm,Skander Vandenheuvel,Rob Vishny,and Baolian Wang for many for detailed and helpful comments,as well as seminar participants at University of Texas at Austin,Chicago Booth,New York University Stern,Harvard Economics,the Federal Reserve Board of Governors,the Federal Reserve Bank of San Francisco,the Society for Economic Dynam-ics2010Annual Meeting in Montreal,and the2010Stanford Institute for Theoretical Economics for detailed and helpful comments.DOI:10.1111/joﬁ.12235733734The Journal of Finance Ris a size effect in bank stock returns that is different from the market capital-ization effects that have been documented in nonﬁnancial stock returns(see Banz(1981)and many others).All else equal,a100%increase in a bank’s book value lowers its annual return by2.23%per annum.For nonﬁnancial stocks, there is no similar relation between book value and returns(Berk(1997)). These return differences cannot be imputed to differences in standard risk exposure.A long position in the stock portfolio of the largest commercial banks, measured by deciles of total book value,and a short position in the stock portfolio of the smallest banks underperforms an equally risky portfolio of all (nonbank)stocks and bonds by more than7%per annum.The average alphas are small but positive for commercial banks in theﬁrstﬁve deciles and then decrease for the largest banks in the top three deciles.Small banks differ from large banks in many ways,but these differences should not lead to differences in average risk-adjusted returns on bank port-folios unless there is bank-speciﬁc tail risk that is priced but not spanned by the traded returns on other stocks in the sample.Weﬁnd evidence of such a risk factor in bank stock returns:the second principal component of the risk-adjusted returns on size-sorted portfolios of commercial banks is a size factor that has exactly the right covariance with the portfolio returns to account for most of this pricing anomaly.By construction,this size factor is orthogonal to the stock and bond risk factors.This highly levered size portfolio,determined by the second principal com-ponent,which goes long in small bank stocks and short in large bank stocks, loses an average of41cents during National Bureau of Economic Research (NBER)recessions per dollar invested at the start,after hedging out exposure to standard stock and bond risk.We attribute the cyclical banking size factor in the data to size-dependent differences in the perceived shareholder recovery rates on these bank portfolios duringﬁnancial disasters.In a version of the Barro(2006),Rietz(1988),and Longstaff and Piazzesi (2004)asset pricing model with a time-varying probability of rare events,de-veloped by Gabaix(2012),Wachter(2013),and Gourio(2008),ﬁnancial disas-ters that disproportionately impact bank cashﬂows contribute an additional bank-speciﬁc risk factor.These rare events are priced into the expected returns on portfolios of banks,but are not fully spanned by the returns on other assets in a small sample.A general equilibrium version of our model can match the average alphas in a sample without disasters if theﬁnancial disaster recovery rate is35cents higher for large banks,in line with the failure rate of banks in the lowest decile during the latest crisis.Historically,the probability of aﬁnancial disaster increases during reces-sions.Because of the size-contingent nature of the recovery rate for bank stock-holders in the case of aﬁnancial disaster,the variation in the probability of aﬁnancial disaster generates a common business cycle factor in the normal risk-adjusted returns of size-sorted bank stock portfolios;the loadings of bank stock portfolio returns on this size factor are determined by the recovery rates and hence by size.Small banks have positive loadings while large banks haveSize Anomalies in U.S.Bank Stock Returns735 negative loadings.As the probability of aﬁnancial disaster increases,the ex-pected return gap between small and large banks grows.In the United States,shareholder recovery rates for banks depend on size. Duringﬁnancial disasters,large banks fare much better,even though they are more levered than their smaller counterparts.A total of30%of publicly traded commercial banks in theﬁrst size decile were delisted in2009but there were no delistings in the last decile.Why study the effect of bailouts on bank equity?The anticipation of future bailouts of bondholders and other creditors always beneﬁts shareholders(see Kareken and Wallace(1978))ex ante.Furthermore,during a crisis,there may be massive uncertainty about the resolution regime,especially for largeﬁnan-cial institutions.As a result,government guarantees will inevitably tend to beneﬁt shareholders ex post as well.Clearly,the ernment and regu-lators are willing to let small banks fail,but not large banks.Acharya and Yorulmazer(2008)point out that bailouts may be ex post efﬁcient if a sufﬁ-ciently large fraction of banks is impacted.Of course,ex ante,one could have expected that the government would wipe out shareholders of largeﬁnancial institutions in the case of a bailout.Our evidence suggests that this is not what market participants expect.Government guarantees essentially grant stockholders of large banks a menu of path-dependent put options that can only be exercised after large declines in a broad index of stocks.This essentially reduces the negative co-skewness of large bank stock returns,but not of small banks.In our sample,large bank stock returns are indeed less negatively skewed and feature less co-skewness, even though the Harvey and Siddique(2000)skewness factors constructed from nonﬁnancial stocks cannot fully account for the variation in average returns on size-sorted bank portfolios.To back out the implicitﬁnancial tail risk premium or discount charged by the shareholders of commercial banks,we multiply the loadings on the size factor by its risk price.The implicit insurance provided againstﬁnancial disaster risk lowers the expected equity return for the largest mercial banks by1.97%,but the additional exposure to bank-speciﬁc tail risk increases the expected return on the smallest bank stocks by2.85%,compared to a portfolio of nonbank stocks and bonds with the same standard risk characteristics.The largest banks have an average market capitalization of$140billion in2005 dollars.For the largest commercial banks,this amounts to an annual savings of $2.76billion per bank.The market imposes largeﬁnancial tail risk“subsidies”(“taxes”)on large(small)bank stocks compared to a portfolio of stocks and bonds with the same observed risk proﬁle.There is direct evidence from option markets to support this conclusion:Kelly,Lustig,and Nieuwerburgh(2011)ﬁnd that out-of-the-money put options on large banks were cheap during the crisis.The pricing ofﬁnancial tail risk depends not only on bank size.We relate theﬁnancial disaster premium of banks to the regulatory mercial banks,which have access to the discount window and beneﬁt from deposit insurance,and government-sponsored enterprises(GSEs),which beneﬁt from736The Journal of Finance Ran explicit guarantee,are imputed a largeﬁnancial tail risk subsidy while investment and foreign banks are not.On the other hand,hedge funds are imputed aﬁnancial tail risk tax,just like small banks.After the repeal of key provisions in the Glass-Steagall Banking Act in1999, weﬁnd large across-the-board increases in the size of the subsidy for large commercial banks,investment banks,and GSEs.For example,the Fannie Mae subsidy tripled to5.93%over the period2000to2005.This period also coincides with dramatic growth in securitization,which allowsﬁnancial institutions to beneﬁt from the collective bailout option more aggressively by eliminating idiosyncratic risk exposure(see Brunnermeier and Sannikov(2014)for a clear description of this effect of securitization).Furthermore,we provide a direct link to bailouts.We show that theﬁnancial disaster subsidy of the largest10banks increases immediately after bailout announcements.O’Hara and Shaw(1990)document large positive wealth ef-fects for shareholders of banks that were declared“too big to fail”by the Comptroller of the Currency in1984,and negative wealth effects for other banks.Consistent with this result,we document large increases in the implicit ﬁnancial disaster subsidy to the too-big-to-fail banks after this announcement, and six other bailout announcements prior to the recentﬁnancial crisis iden-tiﬁed by Kho,Lee,and Stulz(2000).Furthermore,weﬁnd large increases after announcements that beneﬁted large banks during the recentﬁnancial crisis.The rest of this paper is organized as follows.Section I discusses the related literature.In Section II,we construct portfolios of commercial U.S.bank stocks sorted by size as measured by the market capitalization and the book value. Presumably,the government cares about the size of the entire balance sheet. Section III describes the size effect in bank stock returns.Section IV establishes that there is a procyclical size factor in the normal risk-adjusted returns of these portfolios.Section V relates the pricing of bank tail risk to government announcements and the regulatory environment.We use a calibrated version of the model to back out the implied differences in recovery rates in Section VI,and we use the model to explain how government puts for the largest banks may also impact the expected returns of smaller banks.Section VII concludes.I.Related LiteratureA large literature inﬁnance considers size effects in stock returns(see Banz (1981),Basu(1983),Lakonishok,Shleifer,and Vishny(1993),Fama and French (1993),Berk(1995),and others),but most of these papers do not includeﬁnan-cial stocks,presumably because of their high leverage.Our paper is theﬁrst to document that the size effect inﬁnancial stocks is really about size,rather than market capitalization.We attribute the size effect to how tail risk is priced in ﬁnancial stocks.There is direct evidence from option markets that tail risk in theﬁnancial sector is priced differently.Kelly,Lustig,and Nieuwerburgh(2011)ﬁnd that theSize Anomalies in U.S.Bank Stock Returns737 out-of-the-money index put options of bank stocks were relatively cheap during the recent crisis,as a consequence of the government absorbing sector-wide tail risk.In related work on bank stock returns,Fahlenbrach,Prilmeier,and Stulz(2012)document that those banks that incurred substantial losses during previous crises were more likely to incur losses during the recent crisis.If some banks beneﬁt from a larger perceived tail risk subsidy,they have an incentive to load up on this type of risk.In fact,shareholder value maximization requires that they do so,as pointed out by Panageas(2010a),who analyzes optimal risk management in the presence of guarantees.Interestingly,Fahlenbrach, Prilmeier,and Stulz(2012)ﬁnd some evidence that banks whose managers’interests were more aligned with shareholders actually performed worse during the recentﬁnancial crisis.Our work contributes to the important task of measuring systemic risk in theﬁnancial sector.Acharya,Brownless,et al.(2011),Acharya,Pedersen,et al. (2011),Adrian and Brunnermeier(2010),and Huang,Zhou,and Zhou(2009) develop novel methods for measuring systemic risk.Our measure of the bank-ing tail risk premium is determined by the bank’s loading on the size factor, which gauges aﬁrm’s systemic risk exposure.Firms that are deemed system-ically important have large negative loadings on the size factor,because these are less likely to be allowed to fail in the event of aﬁnancial disaster,and they trade at a premium as a result.As far as we know,our paper is theﬁrst to link the subsidy that accrues to banks deemed systemically important with exposure to systemic risk.To the extent that these differences in bank tail risk pricing are directly attributable to government policies,they are an ex ante measure of the distortion created by the implicit guarantee extended to some U.S.ﬁnancial institutions.Estimating the entire ex post realized cost of the various measures implemented by the U.S.Treasury,the Federal Reserve system,the FDIC,and other regulators in the face of the recent crisis is hard. Veronesi and Zingales(2010)estimate the cost to be between$21billion and $44billion,with a beneﬁt of more than$86billion.II.Size Effect in Bank Stock ReturnsThis section reports returns on size-sorted portfolios of commercial bank stocks.We also show the results of a cross-sectional regression of returns on ﬁrm characteristics that conﬁrm the portfolio results.We collect data on equity returns from the Center for Research in Security Prices(CRSP).There is no unique,fullproof way of identifying all of the U.S. commercial banks in CRSP.Many papers in the literature identify these banks manually over short samples.This is not feasible in our study.Instead,we deﬁne commercial banks as allﬁrms with header Standard Industrial Classi-ﬁcation(SIC)codes60or historical SIC code6712.This deﬁnition ensures that bank holding companies are consistently included in our sample.Bank holding companies need to be included in this deﬁnition because the banks that belong to a holding company are not publicly traded themselves.738The Journal of Finance RWe use the header SIC codes(HSICCD)on December2013rather than the historical SIC codes(SICCD)to identify theseﬁrms in the data.1When we screen the CRSP database for SICCDs equal to60or67,several of the largest U.S.banks drop out of the sample,including BB&T Corp,Banc One Corp, Barclays,Citigroup,First Bancorp,and Sterling Bancorp.All of these banks are identiﬁed by the Federal Reserve as one of the largest100deposit-taking institutions in the United States.These banks clearly belong in our sample. The HSICCD screen correctly identiﬁes these commercial banks throughout the sample,because the coding conventions were changed in the late1990s. Conversely,we deﬁne nonﬁnancials as allﬁrms excluding those with two-digit HSICCDs ranging from60to67.The Internet Appendix includes a detailed discussion of these choices.2We exclude data for allﬁnancialﬁrms that are inactive and we also exclude ﬁnancialﬁrms that are not incorporated in the United States because these ﬁnancialﬁrms are subject to regulations both in the country of operation and the country of incorporation.Since these policies vary across countries,our focus onﬁnancialﬁrms operating and incorporated inside the United States ensures that allﬁrms in our analysis are subject to a uniform regulatory regime. Foreignﬁrms are identiﬁed by share codes ending in2or5.We start by building portfolios of domestic commercial bank stocks.We em-ploy the standard portfolio formation strategy of Fama and French(1993).We rank all bank stocks by market capitalization as of January of each year.The stocks are then allocated to10portfolios based on their market capitalization. We calculate value-weighted returns for each portfolio for each month over the next year.At the end of this exercise,we have monthly value-weighted returns for each size-sorted portfolio of banks.The data start in January1970and end in December2013.Only a small fraction of all banks that operate in the United States are publicly listed. For instance,for the years2000to2008,data are available from CRSP for approximately630banks,as compared to more than5,300FDIC-insured banks operating in the United States over the same period.However,the largest 600banks control more than88%of all commercial bank assets in the United States.Most of these large banks are publicly listed.To the extent that small banks that are not publicly listed are very different from those that are,some of our results need to be qualiﬁed.Presumably,the government cares about the entire balance sheet of banks, not just their equity.As a result,book value may be the better measure of size. We follow a similar strategy for forming portfolios of commercial bank stocks sorted by book value.We rank all bank stocks by book value as of December of each year.Book values for all bank stocks are obtained from the merged CRSP-COMPUSTAT database.We calculate value-weighted returns for each portfolio 1The complete panel of commercial banks that fall under our deﬁnition is available from the authors.2The Internet Appendix is available in the online version of the article on the Journal of Finance website.Size Anomalies in U.S.Bank Stock Returns739 for each month over the next year.While our market capitalization results are based on17,594bank-years from1980to2013,the book value results are based on only14,403bank-years.The reduction in the number of banks is primarily due to missing balance sheet data in the CRSP-COMPUSTAT merged data set.While the CRSP data are available from1926,our main sample of banks begins only in1970,as there are not enough publicly traded commercial banks prior to1970.In addition,data for book value of commercial banks are not available for a substantial number of banks in our portfolio in COMPUSTAT prior to1980.Hence,our main sample for book value size-sorted portfolios begins only in1980.III.Size Effect in Normal Risk-Adjusted Bank Stock ReturnsWe start by adjusting the portfolio returns for exposure to the standard risk factors that explain cross-sectional variation in average returns on other port-folios of nonﬁnancial stocks and bonds.We do so by comparing the performance of the bank portfolio to the performance of a portfolio of nonbank stocks and bonds with the same exposure to normal risk factors.To do so,we use the Fama and French(1993)three-factor model.Weﬁnd that small banks,measured ei-ther by market cap or book value,outperform the benchmark portfolio of bonds and stocks,while large banks underperform.A bank manages a portfolio of bonds of varying maturities and credit risk.3 Therefore,we also include two bond risk factors in addition to three stock risk factors,f t=[market smb hm l ltg crd],(1) where f t is5×1.The terms market,smb,and hm l represent the returns on the three Fama-French stock factors,namely,the market,small minus big, and high minus low factors,respectively.The Fama-French stock factors are constructed using the six value-weighted portfolios of all stocks on NYSE, Amex,and NASDAQ(includingﬁnancials)formed on size and book-to-market. We capture market using the value-weighted return on all NYSE,Amex,and NASDAQ stocks(from CRSP)minus the one-month Treasury bill rate(from Ibbotson Associates).We use ltg to denote the excess returns on an index of 10-year bonds issued by the U.S.Treasury as ourﬁrst bond risk factor.The U.S.10-year Government Bond Total Return Index(ltg)is downloadable from Global Financial Data.We use crd to denote the excess returns on an index of investment grade corporate bonds,maintained by Dow Jones,as our second 3Flannery and James(1984)were theﬁrst to demonstrate a link between interest rate changes and common stock returns of commercial banks that depends on the maturity structure of their assets and liabilities.Longstaff and Myers(2009)also show that banks can be treated as active managers ofﬁxed income portfolios.740The Journal of Finance Rbond risk factor.To compute excess returns,we use the one-month risk-free rate.4A.Risk-Adjusted Returns on Commercial Bank Stock PortfoliosWe regress monthly excess returns for each size-sorted portfolio on the three Fama-French stock factors and two bond factors.For each portfolio i we run the following time-series regression to estimate the vector of betasβi:R i t+1−R ft+1=αi+βi, f t+1+εi t+1,(2)where R it+1is the monthly return on the i th size-sorted portfolio.Since all ofthe risk factors in f t are traded returns,the estimated residuals in the time series-regression are estimates of the normal risk-adjusted returns R i t+1. Market Capitalization.Table I provides the results of the regression speciﬁed in equation(2).The portfolios are ranked from smallest(1)to largest(10).Panel A reports the results based on sorting by market capitalization into deciles.The table reports the regression coefﬁcients for each size-sorted portfolio,along with their statistical signiﬁcance and adjusted R2.Table I excludes the recent ﬁnancial crisis.The estimated intercepts decrease nearly monotonically with bank size from 1.94%for theﬁrst decile to−5.09%for the tenth decile.The negative alpha on the tenth decile is signiﬁcantly different from zero at the1%level.A signiﬁcant share of this alpha is due to the very largest banks.We also split the highest decile in two bins,10A and10B.In the top half of the tenth decile(10B) the alpha is−5.60%(statistically signiﬁcant at the1%level),while it is only −3.13%in the bottom half of the tenth decile.If we split the top decile into three bins instead,the top3.33%earns−6.78%per annum(not reported in the table,statistically signiﬁcant at the1%level).The top3.33%accounts for more than90%of the industry’s market capitalization.Clearly,the largest U.S. commercial banks earn signiﬁcantly negative risk-adjusted returns.A long-short position that goes long$1in a portfolio of the largest market capitalization banks in decile10and short$1in a portfolio of the smallest market capitalization banks in decile1loses7.03%over the entire sample. This return spread is statistically signiﬁcant at the5%level.The difference between10A and10B is2.47%and accounts for35%of the entire7.03%spread between theﬁrst and last deciles.The total difference between10B and1is 7.54%.When we split the top decile into three bins,the spread between theﬁrst decile and the top3.33%in the market cap distribution is even larger:8.72% (not reported in the table).When we exclude the largest banks,the differences in risk-adjusted returns are much smaller.The average normal risk-adjusted return on a9-minus-2position is−4.26%per annum,and−5.29%per annum for the8-minus-3portfolio.4Data for the risk-free rate and the Fama-French factors were collected from Kenneth French’s website.The Dow Jones Corporate Bond Return Index(crd)is downloadable from Global Financial Data.Size Anomalies in U.S.Bank Stock Returns741T a b l e IR i s k -A d j u s t e d R e t u r n s o n S i z e -S o r t e d P o r t f o l i o s o f C o m m e r c i a l B a n k sT h i s t a b l e p r e s e n t s e s t i m a t e s f r o m O L S r e g r e s s i o n o f m o n t h l y v a l u e -w e i g h t e d e x c e s s r e t u r n s o n e a c h s i z e -s o r t e d p o r t f o l i o o f d o m e s t i c c o m m e r c i a l b a n k s o n t h e t h r e e F a m a a n d F r e n c h (1993)s t o c k a n d t w o b o n d r i s k f a c t o r s .U .S .c o m m e r c i a l b a n k s a r e d e ﬁn e d a s a l l ﬁr m s w i t h H S I C C D e q u a l t o 60o r h i s t o r i c a l S I C C D e q u a l t o 6712.W e e x c l u d e f o r e i g n b a n k s w i t h s h a r e c o d e s e n d i n g i n 2o r 5.m a r k e t ,s m b ,a n d h m l a r e t h e t h r e e F a m a -F r e n c h s t o c k f a c t o r s :m a r k e t ,s m a l l m i n u s b i g ,a n d h i g h m i n u s l o w ,r e s p e c t i v e l y .l t g i s t h e e x c e s s r e t u r n o n a n i n d e x o f l o n g -t e r m g o v e r n m e n t b o n d s a n d c r d i s t h e e x c e s s r e t u r n o n a n i n d e x o f i n v e s t m e n t -g r a d e c o r p o r a t e b o n d s .∗,∗∗,a n d ∗∗∗i n d i c a t e s t a t i s t i c a l s i g n i ﬁc a n c e a t t h e 10%,5%,a n d 1%l e v e l s ,r e s p e c t i v e l y .A l p h a s a r e a n n u a l i z e d b y m u l t i p l y i n g b y 12a n d a r e e x p r e s s e d i n p e r c e n t a g e s .S t a n d a r d e r r o r s a r e a d j u s t e d f o r h e t e r o s k e d a s t i c i t y a n d a u t o c o r r e l a t i o n u s i n g N e w e y -W e s t (1987)w i t h t h r e e l a g s .T h e s a m p l e i s 1970t o 2013i n P a n e l A ,1980t o 2013i n P a n e l B .S m a l l 23456789L a r g e 10A 10B 10-110A -110B -1P a n e l A :M a r k e t C a p i t a l i z a t i o nα1.941.123.28∗−0.161.04−0.14−1.49−2.01−3.14*−5.09***−3.13−5.60***−7.03**−5.06∗−7.54***m a r k e t 0.46***0.55***0.50***0.59***0.57***0.68***0.78***0.81***0.92***1.22***0.98***1.24***0.76***0.52***0.78***s m b 0.40***0.42***0.38***0.41***0.39***0.44***0.49***0.44***0.42***−0.13∗0.14**−0.15**−0.53***−0.26**−0.55***h m l 0.50***0.48***0.44***0.54***0.49***0.59***0.69***0.66***0.65***0.70***0.58***0.73***0.19∗0.080.22**l t g −0.19−0.07−0.050.090.15∗0.060.140.24**0.39***0.19∗0.24**0.24**0.38**0.43**0.43***c rd 0.36∗0.230.29**0.140.110.21∗0.04−0.06−0.16−0.14−0.04−0.19−0.49**−0.40∗−0.55**R 225.3743.6843.2049.8451.9659.7460.8962.1666.5068.0162.0265.7327.4214.3227.59P a n e l B :B o o k V a l u eα2.221.932.432.621.301.07−1.40−3.53−5.21**−5.70**−4.59∗−6.14**−7.92***−6.81**−8.36**m a r k e t 0.44***0.46***0.54***0.54***0.65***0.79***0.89***0.88***0.90***1.07***1.07***0.83***0.64***0.64***0.40***s m b 0.38***0.38***0.30***0.38***0.46***0.54***0.58***0.60***0.32***0.020.010.04−0.36***−0.37***−0.34***h m l 0.36***0.39***0.44***0.51***0.60***0.75***0.85***0.85***0.73***0.68***0.69***0.42***0.32**0.33**0.07l t g 0.110.110.110.06−0.020.19∗0.42***0.45***0.35***0.050.040.22∗−0.06−0.070.11c r d 0.110.150.150.21∗0.32∗0.08−0.13−0.22−0.140.200.170.170.090.070.06R 234.0139.8539.2947.6649.1357.5362.4757.6863.4756.5350.0340.2722.5419.909.73。

粪菌移植治疗炎症性肠病的研究进展

炎症性肠病（inflammatory bowel disease ，IBD ）是一组以慢性、复发性、异质性为临床特征的肠道炎症性疾病，包括溃疡性结肠炎（ulcerative colitis ，UC ）和克罗恩病（Crohn's disease ，CD ）[1]。

溃疡性结肠炎主要累及结直肠，常以直肠末端为起始点向近端进行性、弥漫性、连续性扩展蔓延；而克罗恩病则可累及全部消化道，呈节段性，纵行溃疡、黏膜铺路石样改变等为其典型肉眼表现[2]。

目前IBD 已影响超过2000万人，约占全球人口的0.3%，并在亚洲地区呈不断攀升趋势，印度和中国发病率最高，分别为9.31/10万人和3.64/10万人[3-4]。

据预测，到2050年，我国IBD 患者将超过150万人[5]。

粪菌移植治疗炎症性肠病的研究进展叶雨松，周雪芹，颜琼，钟晓琳，吕沐瀚西南医科大学附属医院消化内科（泸州646000）【摘要】炎症性肠病（inflammatory bowel disease，IBD ）是一组以肠道炎症和黏膜损伤为主要特征的慢性非特异性肠道炎症性疾病，包括溃疡性结肠炎（ulcerative colitis，UC ）和克罗恩病（Crohn's disease，CD ）。

其病因复杂，相关发病机制目前尚未完全明确，一般认为遗传、环境、免疫等因素之间的相互作用是导致IBD 发生发展的主要原因。

随着研究的不断深入，人们发现肠道菌群紊乱、肠黏膜屏障破坏等在IBD 的进展中亦发挥着重要作用。

IBD 常规内科药物治疗疗效有限且容易出现较大不良反应，因此近年来包括粪菌移植（fecal microbiota transplantation，FMT ）在内的旨在调节肠道微生物群的新型IBD 治疗方法受到国际医学界的广泛关注。

因此，本文就IBD 的发病因素、菌群与机体、IBD 间的联系，粪菌移植治疗IBD 的机制及相关有效性与安全性进行评述，以期为临床治疗IBD 提供参考与借鉴。

(2010)Predictable climate dynamics

Predictable climate dynamics of abnormal East Asian winter monsoon:once-in-a-century snowstorms in 2007/2008winterZhiwei Wu •Jianping Li •Zhihong Jiang •Jinhai HeReceived:9March 2010/Accepted:22October 2010/Published online:5November 2010ÓSpringer-Verlag 2010Abstract In 2008(January–February),East Asia (EA)experiences the most severe and long-persisting snowstorm in the past 100years.Results in this study show that 2007/2008winter is dominant by the third principal mode of the East Asian winter monsoon (EAWM)which explains 8.7%of the total surface air temperature variance over EA.Signiﬁcantly distinguished from the ﬁrst two leading modes,the third mode positive phase features an increased surface pressure over the northwestern EA,an enhanced central Siberian high (CSH),a strengthened and north-westward extended western Paciﬁc subtropical high (WPSH)and anomalously strong moisture transport from western Paciﬁc,Arabian Sea and Bay of Bengal to EA.It also exhibits an intimate linkage with the sea surface temperature anomalies (SSTAs)in the Arctic Ocean areas adjacent to northern Eurasian continent,central North Paciﬁc and northeastern Paciﬁc.Such SSTAs emerge in prior autumn and persist through ensuing winter,signifying precursory conditions for the anomalous third EAWM mode.Numerical experiments with a simple general cir-culation model demonstrate that the Arctic SSTAs excite geo-potential height anomalies over northern Eurasian continent and impacts on the CSH,while the extra-tropicalPaciﬁc SSTAs deform the WPSH.Co-effects of them play crucial roles on origins of the third EAWM mode.Based on these results,an empirical model is established to predict the third mode of the EAWM.Hindcast is performed for the 1957–2008period,which shows a quite realistic pre-diction skill in general and good prediction ability in the extreme phase of the third mode of the EAWM such as 2007/2008winter.Since all these predictors can be readily monitored in real time,this empirical model provides a real time forecast tool and may facilitate the seasonal prediction of high-impact weather associated with the abnormal EAWM.Keywords Seasonal prediction ÁEast Asian winter monsoon ÁSnowstorm1IntroductionIn 2008(January–February),East Asia (EA)(particularly China)experiences a record-breaking (most severe in many decades)and long-persisting snowstorm and leads to huge property loss and hundreds of people’s death.In the meanwhile,severe snowstorms also attacked North America and Russia.The central Asia even experienced the ﬁrst snowfall in the last 100years (/content/2008-02/03/content_1141936.htm ).Such series of disastrous climate events inevitably receive broad scientiﬁc foci and trigger fervent research interests on the East Asian winter monsoon (EAWM)(e.g.,Tao and Wei 2008;Ding et al.2008;Wen et al.2009;Hong and Li 2009;Bao et al.2010).Inspecting possible physical mechanisms responsible for the abnormal EAWM in 2007/2008winter,especially its predictability sources,could not only improve understanding the variation rules of the EAWM,but alsoZ.Wu ÁJ.Li (&)LASG,Institute of Atmospheric Physics,Chinese Academy of Sciences,100029Beijing,China e-mail:ljp@Z.WuMeteorological Research Division,Environment Canada,Dorval,QC H9P 1J3,CanadaZ.Jiang ÁJ.HeKey Laboratory of Meteorological Disaster of Ministry of Education,Nanjing University of Information Science and Technology,Nanjing,ChinaClim Dyn (2011)37:1661–1669DOI 10.1007/s00382-010-0938-4beneﬁt seasonal prediction of high-impact weather associ-ated with the abnormal EAWM.The EAWM exhibits pronounced oscillations from interannual to multi-decadal timescales(e.g.,Li1955;Tao 1957;Ding and Krishnamurti1987;Chan and Li2004; Jhun and Lee2004;Chang et al.2006,2009;Li and Bates 2007;Wu et al.2009a).Wang et al.(2010)found that the EAWM is usually dominated by two distinct principal modes,namely,the northern mode and the southern mode in terms of the surface air temperature(SAT)variability. These two leading modes bear distinguished circulation structures and different causes.El Nin˜o-Southern Oscilla-tion(ENSO),snow cover over the southern and north-eastern Siberian,and sea surface temperature(SST)of North Atlantic and tropical Indian Ocean are major impact factors for the two leading modes.In2007/2008winter,the EAWM displayed many distinct features which neither belong to a typicalﬁrst mode EAWM nor a second mode documented by Wang et al.(2010).Since most previous studies chose to consider it as a once-in-a-century(or extremely rare)case,they focused more on its uniqueness than its universality and investigations were conducted along this line.For example,Tao and Wei(2008)empha-sized roles of the sustaining blocking high in the mid-high latitudes over EA based on synoptic scale analysis of the snowstorm events in January2008.Ding et al.(2008) suggested the strong La Nin˜a event in2007/2008winter provides a climate background for invasion of cold air into South China and the persistence of circulation anomalies over the Eurasian continent is the direct cause of the snowstorms.Wen et al.(2009)believed these snowstorms were closely linked to the change in the Middle East jet stream and the anomalous western Paciﬁc subtropical high (WPSH).Besides the above mentioned,the tropical intra-seasonal oscillation and anomalous Tibetan Plateau warming are also suggested to be responsible for the anomalous2007/2008snowstorms(Hong and Li2009;Bao et al.2010).Although the catastrophic consequences of the2007/ 2008winter snowstorms are unprecedented or once-in-a-century(Zheng2008;Wang et al.2008),several similar cases do occur in the past50years.This provides the feasibility of investigating the general features of the2007/ 2008-like EAWM anomalies and their predictability sour-ces.This study attempts to answer the following questions: What kind of principal mode dominates the abnormal 2007/2008winter monsoon over EA?What are the com-mon features of the2007/2008-like EAWM anomalies? The most important issue might be how to predict such winter monsoon anomalies.This paper is structured as follows.Section2describes the datasets,the numerical model and the methodology used in this study.Section3suggests that2007/2008winter is dominated by the third principal mode of the EAWM.Section4investigates the predictability sources of the third mode and Sect.5discusses the possible physical mechanisms on the2007/2008-like EAWM anomalies with a simpliﬁed general circulation model(SGCM).In Sect.6, an empirical model is established to forecast the EAWM third mode based on the above predictability sources. Hindcast is performed for the1957–2008period.The last section summarizes majorﬁndings and discusses some outstanding issues.2Data,model and methodologyThe main datasets employed in this study include(1) monthly observed SAT and precipitation data from160 gauge stations across China for the1957–2009period;(2) European Centre for Medium-Range Weather Forecasts (ECMWF)40-year reanalysis data(ERA-40;Uppala et al. 2005)and ERA-interim reanalysis datasets;(3)the Met Ofﬁce Hadley Centre’s sea ice and SST datasets gridded at 1.0°91.0°resolution(Rayner et al.2003).To maintain temporal homogeneity,the2002–2009ERA-interim data were adjusted by removing the climatological difference between the ERA-40and ERA-interim datasets.In this study,winter(December,January,and February or DJF) mean anomalies are deﬁned by the deviation of DJF mean from the long-term(1958–2008)mean climatology.All the numerical experiments presented in this paper are based on the SGCMﬁrst developed by Hoskins and Simmons(1975).The resolution used here is triangular31, with ten equally spaced sigma levels(Lin and Derome 1996).An important feature of this model is that it uses a time-averaged forcing calculated empirically from observed daily data.As shown in Hall(2000),this model is able to reproduce remarkably realistic stationary planetary waves and the broad climatological characteristics of the transients are in general agreement with observations.To reveal the leading modes of the EAWM,we per-formed EOF analysis of the SAT over EA(10°–60°N, 100°–140°E).The EOF analysis was carried out by con-structing a correlation matrix to eliminate the geographical inﬂuences.As such,the eigenvectors(spatial patterns)are non-dimensional.3Distinct third principal mode of the EAWM variabilityFigure1presents the spatial patterns and the corresponding principal components(PCs)of the three leading modes of the EAWM SAT variability.The two leading modes bear similar spatial patterns with the northern and southernmodes documented in Wang et al.(2010)(Fig.1a,c).It is of interest to notice that the PC3in2007/2008winter reaches the highest value within the pastﬁve decades (Fig.1f).The third mode accounts for around8.7%of the total SAT variances,while the fourth mode explains5.4% of the total SAT variances.The eigenvalues of the leading modes suggest that EOF3is signiﬁcantly distinguished from EOF1and EOF2and other modes in terms of sam-pling error above the95%conﬁdence level(North et al. 1982).The spatial pattern of EOF3shows that during a positive phase of the third mode,anomalous cold SAT tends to occur in southern China-west Mongolia and anomalous warm in central Siberia and Philippine Sea,and vice versa.Since the third mode explains around8.7%of the total SAT variance,it will not become dominant in a year unless the other leading modes carry relatively small variance for this year.In2007/2008winter,the third mode can explain more than70%of the total SAT variance,which is the highest in the past52years(Fig.2a).As a matter of fact, totally there were four winters in which the third mode becomes dominant and accounts for more than40%of the total variance for the1957–ing observa-tional data at160gauge stations across China,as expected, 2007/2008does exhibit a typical high PC3winter feature in terms of the SAT spatial pattern,namely,anomalous cold SAT in southern China and anomalous warm in north-eastern China(color shadings in Fig.2a).The spatial pat-terns of the observed SAT in the other three PC3winters (color shadings in Fig.2b–d)are similar to that in2007/ 2008winter(color shadings in Fig.2a).In addition,the observed precipitation anomalies of theﬁrst three winters share a similar pattern,in spite that those in1971/1972 exhibit some differences(contours in Fig.2).Figure3shows the composite difference of circulation anomalies between the high and low PC3winters(high minus low).Note that the high or low PC3winters in this study refer to those in which the third mode is dominant and accounts for more than25%of the total variance.There are six high PC3and three low PC3winters in total from1957 through2008(see those blank circles in Fig.1f).At lower troposphere,a notable positive sea-level pressure(SLP) center occupies northern EA with a SLP ridge extending northwestward and signiﬁcant anticyclonic winds.This pattern reﬂects a route of cold air intrusion via a‘‘northwest pathway’’.Negative SLP anomalies control Tibetan Pla-teau,which favors moisture transport from the Bay of Bengal toward southern China along the southernﬂank of the Plateau.A pronounced inverse trough and cyclonic winds prevail over Philippine and South China Sea,which indicates a warm and moist air transport from Philippine Sea and western Paciﬁc.There are large pressure gradient between northern China and Philippines.The Europe and North Atlanitic is dominated by a vast high pressure anomaly.At500hPa,a signiﬁcant positive geo-potential high(H)anomaly center is located over central Siberia, which favors development of a blocking high over this region.In the meanwhile,a pronounced positive H center covers northwestern Paciﬁc and extends eastward,associ-ated with an anticyclonic wind center prevailing over the ocean areas south of Japan islands.It favors a northwest-ward WPSH.Over the Tibetan Plateau a huge low pressure system prevails,associated with the Tibetan Plateau warming(Bao et al.2010).To objectively quantify the variability of the third principal mode and to facilitate understanding the inﬂu-ences of local and remote forcing on the mode,it is helpful to pinpoint the most sensitive circulation variability centers with the third principal mode.Boxes in Fig.3show the key regions in the SLP,low-level winds and500hPa H that are best correlated with the PC3.The third principal mode may be gauged by the SLP anomaly difference between north-ern EA(25°–50°N,105°–150°E)and Tibetan Plateau (25°–37°N,75°–93°E)with a correlation coefﬁcient0.68(Fig.3a).This indicates that a strengthening continental High over northern EA and a weakening Tibetan High are two major circulation features accompanies by a strong third principal mode.The third principal mode can also be measured by the averaged meridional winds over(0°–25°N,125°–140°E)and zonal winds over(15°–25°N,70°–100°E)with a correlation coefﬁcient0.55(Fig.3a).It implies that a high third mode winter is usually associated with enhanced moisture transport from the western Paciﬁc, South China Sea and Bay of Bengal.In terms of500hPa H,the third principal mode can be best quantiﬁed by the H difference between central Siberia(55°–70°N,90°–120°E), central North Paciﬁc(20°–35°N,130°–140°W)and TP (25°–50°N,40°–100°E)(namely,H(Siberia)?H(North Paciﬁc)-H(TP)),with a correlation coefﬁcient0.71 (Fig.3b).This means that a strong third principal mode is characterized by enhanced blocking high over central Siberia,intensiﬁed WPSH with a northwestward shift and weakened TP high.Based on the results in Fig.3,we propose that the variability of third principal mode of the EAWM can be measured by the above circulation indices. 4Origins and predictability sources of the third principal modeIn order to reveal origins and possible sources of predict-ability of the third principal mode,we investigate the preceding autumn SST anomalies(SSTAs)and sea ice concentration anomalies(SICAs)associated with thismode.Figure4shows the correlation between PC3and autumn SIC(SST).There are some major signiﬁcant correlation areas in autumn relevant to the third principal mode.One is the anomalously negative SIC correlation area located in Arctic Ocean(120°E–160°W)(Fig.4a).Another is the anomalously positive SST correlation area covering the Arctic Ocean areas adjacent to the northern Eurasian con-tinent.The positive SST correlation is quite likely relevant to the negative SICA correlation,because SST warming always favors SIC decreasing.In spite of the SICAs lack of persistence,the SSTAs can persist through the winter(not shown).This might explain the simultaneous500hPa H positive correlations over the northern Eurasian continent as shown in Fig.3b,since the local low boundary heating (cooling)during the high(low)PC3winters can induce the positive(negative)H anomalies over this region.It is interesting to notice that no signiﬁcant correlation is found with tropical SST in the prior autumn,while large areas of signiﬁcant correlations are detected with extra-tropical SST in North Paciﬁc(Fig.4b)and sustain through the winter(not shown).This indicates that the third mode is more likely to result from the extra-tropical SSTA than ENSO.This result is different from the argument in the previous studies that ENSO provided a condusive condition for the snowstorms in2007/2008winter.Those features derived from the above correlation analysis can also be observed in the composite analysis between the high and low PC3winters(not shown).The SSTAs bear a similar pattern with that in Fig.4b from prior autumn to winter.Such SSTA persistence provides pre-dictability sources for the third principal mode winters.The Arctic SICAs varies signiﬁcantly from prior autumn to winter in the composite analysis,which is most likely due to theﬂowability of the sea ice.Suchﬂowability limits its capacity as a predictability source of the abnormal EAWM. However,the effects of the Arctic SICAs may be reﬂected by SSTAs in the Arctic Ocean areas adjacent to the northern Eurasian continent.To summarize,it may be speculated that the SSTAs in the Arctic Ocean areas adjacent to the northern Eurasian continent and those in extra-tropical North Paciﬁc are two major origins and predictability sources of the third prin-cipal mode of the EAWM.5Physical mechanismsIn this section,we discuss the physical processes through which the lower boundary forcing affects the EAWM variability with the SGCM.To mimic the diabatic heating effects of the SSTAs in Arctic,central North Paciﬁc and northeastern Paciﬁc,we imposed two heating sources and one cooling source;each has an elliptical squared cosine distribution in latitude and longitude with a vertically integrated heating rate of 2.5K/day which is approxi-mately the latent heating rate release given by an extra 10mm precipitation per day(right panel in Fig.5).The magnitude of heating anomaly imposed here is according to the previous work by Hoskin and Karoly(1981).To make the numerical results more robust,the control run was integrated for12years and the last10years’integra-tion was used to derive a reference state.The sensitivity tests were integrated for10years each.The10-year inte-grations were used to construct a10-member ensemble (arithmetic)mean to reduce the uncertainties arising from differing initial conditions.To isolate the roles of the Arctic SSTAs and the Paciﬁc SSTAs,ﬁrst we perform sensitive experiments with the Arctic forcing and the Paciﬁc forcing,separately.It can be clearly seen from Fig.6a that under the Arctic SSTA forcing,550hPa H basically responds an anoma-lously positive anomaly center located over northern Eur-asian continent,which may favor developing and sustaining of the blocking high over this area.Figure6b displays that there are two signiﬁcant550hPa H anomaly centers as responses to the Paciﬁc SSTA forcing.This pattern favors the enhancement and northwestward shift of the WPSH.The physical mechanisms are interpretedasfollows.The warming (cooling)SSTA usually favors high (low)H anomalies due to the sensible heating as the experiments show.On the other hand,high (low)H anomalies would enhance (weaken)solar radiation and maintain the warming (cooling)SSTA.Such positive feedback may sustain such air-sea anomaly pattern.Figure 7shows responses of the atmosphere to forc-ings from both the Arctic and Paciﬁc.The 550hPa H simulation basically captures the major features of the third principal mode of the EAWM,namely,enhanced blocking high over central Siberia and intensiﬁed WPSH with a northwestward shift.It further veriﬁed the specu-lation in Sect.5that the Arctic SSTAs and the SSTAs in the extra-tropical Paciﬁc are two major origins and pre-dictability sources of the third principal mode of the EAWM (Fig.8).6Seasonal predictionTo study how well the above predictability sources con-tribute to the prediction skill of the EAWM thirdmode(Fig.8),an empirical seasonal prediction model is devel-oped using a linear regression method for the period of 1957–2008(see Eq.1).y¼0:3Áx1þ0:26Áx2À0:32Áx3ð1Þwhere x1,x2and x3denotes the prior autumn SSTAs averaged in the Arctic Ocean(70°–85°N,105°E–115°W), central North Paciﬁc(22.5°–35°N,170°E–110°W)and northeastern Paciﬁc(35°–50°N,150°–130°W),respec-tively(Fig.8).The correlation between the simulation and the observation of the PC3is0.55.To test the predictive capability of the empirical model, the cross validation method is performed to hindcast the PC3(1957–2008)(Michaelsen1987;Wu et al.2009b).To warrant the hindcast result robust,we choose a leaving-thirteen-out strategy(Blockeel and Struyf2002).The rel-evant procedures are as following:The cross-validation method systematically deletes13years from the period 1957–2008,derives a forecast model from the remaining years,and tests it on the deleted cases.Note that the choice of‘‘leaving-thirteen-out’’is not random.Blockeel and Struyf(2002)suggested that randomly choosing20–30% of the data to be in a test data and the remainder as a training set for performing regression can prevent overﬁt-ting or wasting data.In our paper,25%of the whole hindcast period(52years)equals to13years.That’s why we choose a leaving-thirteen-out strategy.The cross-vali-dated estimates of the PC3are shown in Fig.9.The cor-relation coefﬁcient between the observation(black line in Fig.9)and the52-year cross-validated estimates of the empirical model(red line in Fig.9)is0.45.To verify theprediction skill in real forecast,we apply a30-year moving training window prior to forecast year and perform a10-year real forecast from1999/2000winter through2008/ 2009winter(Fig.10).The correlation coefﬁcient between the observation and the real forecast is0.59,exceeding 95%conﬁdence level.The2007/2008abnormal EAWM is realistically forecast,even better than the hindcast.It indicates that this empirical seasonal prediction model does show a promising skill in predicting the extreme phase of the abnormal EAWM as2007/2008winter.Since all these predictors can be readily monitored in real time,this empirical model provides a real time forecast tool and may facilitate the seasonal prediction of high-impact weather associated with the abnormal EAWM.7Conclusion and discussionUsing observed data over the past52years(1957–2008), this study attempts to unveil the origins and predictablility sources of the third principal mode of the EAWM which dominated2007/2008winter over EA.Although the third principal mode explains only8.7%of the total SAT vari-ance over EA,it can bring about huge catastrophic con-sequences such as the2007/2008once-in-a-century snowstorms over EA.This mode is signiﬁcantly different from theﬁrst two leading modes documented by Wang et al.(2010).It is characterized of an increased surface pressure over the northwestern EA,an enhanced CSH,and a strengthened and northwestward extended WPSH.Pre-ceded the anomalous third mode EAWM winters,large areas of SSTAs are observed in prior autumn in the Arctic Ocean areas adjacent to northern Eurasian continent,cen-tral North Paciﬁc and northeastern Paciﬁc as well as with the prominent Arctic sea ice concentration anomalies.The SSTAs can persist through ensuing winter,which offers predictability sources for the third mode.Theﬂowability of the SICAs decreases their predictability.However,the Arctic SICAs on the origin of the third EAWM mode may be very critical based on the above results.Their effects can be reﬂected by changing the Arctic SSTAs.To further understand the physical process responsible for circulation anomalies associated with the third prin-cipal mode,three numerical experiments aredesignedwith the SGCM to see atmosphere responses to the forcings originated from the Arctic and the extra-tropical Paciﬁc.Results demonstrate that the Arctic SSTAs excite geo-potential height anomalies over northern Eurasian continent and impacts on the CSH,while the extra-trop-ical North Paciﬁc SSTAs deforms the WPSH and Aleu-tian Low.Co-effects of them play crucial roles on origins of the third EAWM mode and may provide predictability sources of the extreme phases of this mode.Based on these results,an empirical model is established to predict the third mode of the EAWM.Hindcast is performed for the1957–2008period,which shows a quite realistic prediction skill in general and good prediction ability in the extreme phase of the third mode of the EAWM such as2007/2008winter.Since all these predictors can be readily monitored in real time,this empirical model provides a real time forecast tool and may facilitate the seasonal prediction of high-impact weather associated with the abnormal EAWM.However,the SGCM simulation in Fig.7b has biases compared with the observation,especially over the Eur-asian continent(Fig.7a).The discrepancy may come from the model itself and the existence of other predictability sources.The third mode of the EAWM may have other predictability sources,because our empirical model hind-cast explains around20%of the observational variance (their correlation coefﬁcient being0.45).Due to data lim-itation,we onlyﬁnd three predictors.If more and better data are available,the feasibility ofﬁnding other predict-ability sources will increase,correspondingly.Besides the above physical approaches,application of a better mathe-matic strategy of model construction may also improve seasonal prediction skill(e.g.,Li and Smith2009).This is based on the fact that although many physical processes are not fully understood up to now,they can be well depicted, mathematically.How to perfectly combine these two approaches is still an open issue.This work is just a beginning and much more future work needs to do be done to improve seasonal prediction skill of these high impact climate events.Acknowledgments Zhiwei Wu is supported by the Sustainable Agriculture Environment Systems(SAGES)research initiative of Agriculture and Afri-Food Canada through the Natural Sciences and Engineering Research Council of Canada(NSERC)Fellowship Pro-gram.The authors are supported by the Special Research Program for Public Welfare(Meteorology)of China under Grant No. GYHY200906016and the National Basic Research Program‘‘973’’(Grant No.2010CB950400).ReferencesBao Q,Yang J,Liu YM,Wu GX,Wang B(2010)Roles of anomalous Tibetan Plateau warming on the severe2008winter storm incentral-southern China.Mon Wea Rev.doi:10.1175/2009M WR2950.1Blockeel H,Struyf J(2002)Efﬁcient algorithms for decision tree cross-validation.J Mach Learn Res3:621–650Chan J,Li C(2004)The East Asia winter monsoon.In:Chang C-P (ed)East Asian Monsoon.World Scientiﬁc,Singapore, pp54–106Chang CP,Wang Z,Hendon H(2006)The Asian winter monsoon.In: Wang B(ed)The Asian monsoon.Praxis,New York,p89 Chang CP,Lu MM,Wang B(2009)The East Asian winter monsoon.In:Chang C-P et al(eds)The global monsoon system:research and forecast,2nd edn.World Scientiﬁc,Singapore(in press) 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Forecast(in Chinese),China Meteo-rological Administration(eds).Meteorology Press,Beijing, pp60–92Tao SY,Wei J(2008)Severe snow and freezing rain in January2008 in the southern China.Climatic Enviro Res(in Chinese) 13(4):337–350Uppala S,Kallberg PW,Simmons AJ et al(2005)The ERA-40re-analysis.Quart J Roy Meteor Soc131:2961–3012.doi:10.1256/qj.04.176Wang DH,Liu CJ,Liu Y,Wei FY,Zhao N,Jiang ZN,Li Y,Chen JY, Wang YF,Shi XH,Xu XD(2008)A preliminary analysis of features,causes of the snow storm event over the Southern China in January2008.Acta Meteorologica Sinica66(3):405–422 Wang B,Wu ZW,Chang CP,Liu J,Li JP,Zhou TJ(2010)Another look at interannual to interdecadal varaitions of the East Asian winter monsoon.J Clim(in press)。

Anomalous pressure generation within the Alberta Basin implications for oil charge to the Viking

Anomalous pressure generation within the Alberta Basin: implications for oil charge to the Viking FormationE.B.Bekele a,*,M.A.Person b,B.J.Rostron ca CSIRO Land and Water Division,Wembley,Australiab Department of Geology and Geophysics,University of Minnesota,Minneapolis,MN,USAc Department of Earth and Atmospheric Sciences,University of Alberta,Edmonton,CanadaAbstractPrevious studies have shown that hydrodynamics played a pivotal role in the regional transport of hydrocarbons and heat in the Alberta Basin.However,the mechanisms impelling groundwaterﬂow in the basin are controversial.Regional,topography-driven groundwaterﬂow most likely controlled long-range oil migration and modern geothermal gradients,but anomalous pressures also existed during basin evolution.Anomalous pressures in the Alberta Basin consist of two types:overpressures in the past during sediment compaction and hydrocarbon generation,and sub-hydrostaticﬂuid pressures within the modernﬂow system.Groundwaterﬂow,heat transfer,and hydrocarbon generation were simulated using a numerical model for a two-dimensional section of the foreland basin.Simulations are constrained using vitrinite reﬂectance,borehole temperature and hydrologic data.Results indicate that mechanical sedimentary loading and organic maturation produced overpressures within the Colorado Group shales and impelled oil downward to the underlying Viking Formation during the Paleocene.Low permeability aquitards(Յ10Ϫ21m2)facilitate anomalousﬂuid pressure generation over a broad zone.The evolution of anom-alous pressures within petroleum source rocks has signiﬁcant implications for understanding the history of oil charge.᭧2000 Elsevier Science B.V.All rights reserved.Keywords:Overpressure;oil migration;shale permeability;Alberta Basin1.IntroductionRegional,topography-driven groundwaterﬂow in the Alberta Basin played an essential role in long-range oil migration and modern geothermal gradients as shown by previous studies(Hitchon,1984;Garven, 1989;Majorowicz et al.,1999);however,anomalous ﬂuid pressures exist within the modern and paleo-ﬂow systems.Sub-hydrostaticﬂuid pressures exist today within several aquifers and produceﬂow directions to the west,opposite to topography-drivenﬂow (Corbet and Bethke,1992;Bachu,1995;Parks and To´th,1995;Rostron and To´th,1995).Anomalous pressures also inﬂuenced ancient groundwaterﬂow patterns,but unlike the modern ﬂow system,ﬂuid pressures were probably above normal during periods of sediment deposition.Over-pressures most likely induced downward primary oil migration from thick marine shales of the Colorado Group into the underlying Viking Formation,as inferred from oil-source rock correlations(Creaney and Allan,1990);however,the mechanisms control-ling migration have never been quantiﬁed. Mathematical modeling is used to quantify anom-alous pressure generation and primary oil migrationJournal of Geochemical Exploration69–70(2000)601–605 0375-6742/00/$-see front matter᭧2000Elsevier Science B.V.All rights reserved. PII:S0375-6742(00)00064-9www.elsevier.nl/locate/jgeoexp*Corresponding author.Fax:ϩ61-8-9333-6211.E-mail addresses:elise.bekele@per.clw.csiro.au(E.B.Bekele), mperson@(M.A.Person),rostron@darcy. eas.ualberta.ca(B.J.Rostron).directions for the Colorado Group shales.Thermal and hydrologic data provide constraints on simula-tions of regional groundwater ﬂow and convective heat transport.2.Geologic backgroundThe Alberta Basin contains mainly undeformed Paleozoic through early Cenozoic rocks which rest unconformably on the Precambrian Shield (Leckie and Smith,1992).Total sediment accumulations exceed 5km (Fig.1).The Viking Formation is a sand-stone carrier bed within the foreland sequence,which overlies Cambrian to Jurassic carbonates.The Colorado Group shales include highly produc-tive source horizons that supplied oils to the Viking Formation (Creaney and Allan,1990).Full maturity of the Colorado Group shales was largely controlled by maximum sediment burial during the ﬁnal phase of the Laramide orogeny (England and Bustin,1986).The most probable estimate of maximumtemperatures (and presumably maximum burial)in the basin,is 60million years ago,based on a synthesis of apatite ﬁssion track data (Ravenhurst et al.,1994).Several groundwater ﬂow systems are presently active within the Alberta Basin,including shallow,local-scale topography-driven ﬂow within post-Juras-sic strata and regional ﬂow to the west within isolated aquifers (Bachu,1995).Basin topography drives ﬂow from recharge areas in Montana to discharge areas in northeastern Alberta within the pre-Cretaceous layers (Bachu,1995).The hydrodynamics of the Alberta Basin has evolved throughout basin development.Increased sediment accumulation strengthened compaction-driven ground-water ﬂow during the Laramide te stage compression may have driven ﬂuids eastward into the foreland (Ge and Garven,1994),but sediment compac-tion most likely dominated basin hydrodynamics during rapid sediment burial.A second orogenic pulse (Late Paleocene or Early Eocene)resulted in maximum burial and subsequent isostatic uplift which induced topography-driven groundwater ﬂow (Hitchon,1984).E.B.Bekele et al./Journal of Geochemical Exploration 69–70(2000)601–605602Fig.1.Location of the Alberta Basin in western Canada and thickness of Phanerozoic sediments (m)(after Wright et al.,1994).A ﬁnite element model was developed for section line (A–A H ).Gravity-driven groundwaterﬂow was weakened by erosion from the Miocene to the Pliocene(Garven, 1989).The thermal history of the basin includes conductive heat transfer during sediment burial and organic maturation,and thermal convection during basin uplift.Paleo-geothermal gradients derived from apatiteﬁssion track data indicate increased heatﬂow within groundwater discharge areas to the east,near the end of the Laramide (Ravenhurst et al.,1994).Geothermal gradients within the modernﬂow system also increase within groundwater discharge areas in the eastern part of the Alberta Basin.The inﬂux of cool meteoric waters may have produced the observed geothermal gradient pattern;however,variations in basement heatﬂux could play a role(Bachu, 1988;Majorowicz et al.,1999).E.B.Bekele et al./Journal of Geochemical Exploration69–70(2000)601–605603Fig.2.Basin stratigraphy and groundwaterﬂow patterns along a northwest–southeast section line of the Alberta Basin.Hydraulic heads(m)are presented at two times:(a)maximum burial(60million years ago),and(b)today.3.Mathematical modelA two-dimensional mathematical model of ground-water ﬂow,heat transfer and petroleum generation was constructed to study ﬂuid impelling mechanisms in the basin.The cross-sectional model extends 700km east of the limit of foreland deformation and includes more than 35sedimentary layers.The effects of sediment loading and erosional unloading on ﬂuid ﬂow and heat transfer were simulated using the ﬁniteelement model RIFT2D developed by Person et al.(2000).Porosity and permeability values for different hydrostratigraphic units were computed using equa-tions from Corbet and Bethke (1992).4.ResultsQuantitative results are presented for the model that produced the best match to observed hydrologic,ther-mal and petroleum data from the Alberta Basin (Fig.2).Permeability values range from Ͻ10Ϫ21m 2for shale to 10Ϫ15m 2for sandstone.The model indicates compaction-driven ﬂow during maximum sediment burial and primary oil migration to the Viking Forma-tion due to overpressuring in the overlying shales.Overpressures in the western portion of the basin were generated predominantly by mechanical sedi-ment loading with minor pressuring due to organic maturation.The model reproduces sub-hydrostatic ﬂuid pressures and ﬂow directions within the modern ﬂow system.Comparisons of computed versus measured vitri-nite reﬂectance from the Mannville Formation and borehole temperature data indicate that the model reproduces thermal conditions in the basin (Figs.3and 4).Model results produce low average errors (0.19for vitrinite reﬂectance and 0.29for borehole temperatures).Variations in the basement heat ﬂux were not included,but might improve the model ﬁt to measured temperatures.Vitrinite reﬂectance data are from several published sources (Hacquebard,1977;Moshier and Waples,1985;England and Bustin,1986).Temperature data were acquired from boreholes located along section line A–A H (A.Jessop,unpublished data).Quantitative results suggest that the permeability structure of the Alberta Basin is characterized by low permeability aquitards that slowly dissipate anomalous ﬂuid pressures,and high permeability aquifers that facilitate thermal convection via regional groundwater ﬂow.Investigations of anomalous ﬂuid pressures have signiﬁcance for understanding hydrocarbon migration pathways.Overpressure development in sedimentary basins involves a complex relationship between processes that generate and dissipate pressures.E.B.Bekele et al./Journal of Geochemical Exploration 69–70(2000)601–605parison of measured and computed vitrinite reﬂectance from the MannvilleFormation.Fig. parison of measured and computed present-day temperatures.AcknowledgementsThis research was supported in part by a Doctoral Dissertation Fellowship from the University of Minnesota to Elise Bekele.Additional support was provided by the National Science Foundation Instru-mentation and Facilities Grant,and Petroleum Research Fund grants:27964-AC8and32479-AC2 to Mark Person.We would also like to acknowledge the George and Orpha Gibson Hydrogeology Endowment at the University of Minnesota. ReferencesBachu,S.,1988.Analysis of heat transfer processes and geothermal pattern in the Alberta Basin,Canada.J.Geophys.Res.93(B7), 7767–7781.Bachu,S.,1995.Synthesis and model of formation-waterﬂow, Alberta Basin,Canada.AAPG Bull.79(8),1159–1178. Corbet,T.F.,Bethke,C.M.,1992.Disequilibriumﬂuid pressures and groundwaterﬂow in the Western Canada Sedimentary Basin.J.Geophys.Res.97(B5),7203–7217.Creaney,S.,Allan,J.,1990.Hydrocarbon generation and migration in the Western Canada sedimentary basin.Classic Petroleum Provinces,Brooks,J.(Ed.).Geol.Soc.London,Spec.Publ.50,189–202.England,T.,Bustin,R.,1986.Thermal maturation of the Western Canadian Sedimentary Basin south of the Red Deer River, Alberta Plains.Bull.Can.Pet.Geol.34(1),71–90. Garven,G.,1989.A hydrogeologic model for the formation of the giant oil sands deposits of the Western Canada Sedimentary Basin.Am.J.Sci.289,105–166.Ge,S.,Garven,G.,1994.A theoretical model for thrust-induced deep groundwater expulsion with application to the Canadian Rocky Mountains.J.Geophys.Res.99(B7),13,851–13,868. Hacquebard,P.A.,1977.Rank of coal as an index of organicmetamorphism for oil and gas in Alberta.The Origin and Migra-tion of Petroleum in the Western Canada Sedimentary Basin:A Geotechnical Thermal Maturation Study,Tissot,B.,McGros-san,R.G.(Eds.).Geol.Surv.Can.Bull.262,11–22. Hitchon, B.,1984.Geothermal gradients,hydrodynamics,and hydrocarbon occurrences,Alberta,Canada.AAPG Bull.68(6),713–743.Leckie,D.A.,Smith,D.G.,1992.Regional setting,evolution,and depositional cycles of the Western Canada Foreland Basin.Foreland Basins and Fold Belts,Macqueen,R.W.,Leckie,D.A.(Eds.).AAPG Mem.55,9–46.Majorowicz,J.A.,Garven,G.,Jessop,A.,Jessop,C.,1999.Present heatﬂow along a proﬁle across the Western Canada Sedimen-tary Basin:the extent of hydrodynamic inﬂuence.In:Foerster,A.,Merriam, D.F.(Eds.).Geothermics in Basin Analysis,Plenum Press,New York,pp.61–79.Moshier,S.O.,Waples,D.W.,1985.Quantitative evaluation of Lower Cretaceous Mannville Group as source rock for Alberta’s oil sands.AAPG Bull.69(2),161–172.Parks,K.P.,To´th,J.,1995.Field evidence for erosion-induced underpressuring in Upper Cretaceous and Tertiary strata,west central Alberta,Canada.Bull.Can.Pet.Geol.43(3),281–292. Person,M.,Neuzil,C.,Mailloux,B.,Hsieh,P.,Bekele,E.,Swen-son,J.,Eadington,P.,2000.RIFT2D:aﬁnite element model for simulating two-dimensionalﬂuid,heat,and solute mass trans-port within evolving sedimentary basins(in review). Ravenhurst,C.E.,Willett,S.D.,Donelick,R.A.,Beaumont,C., 1994.Apatiteﬁssion track thermochronometry from central Alberta:implications for the thermal history of the Western Canada Sedimentary Basin.J.Geophys.Res.99(B10), 20,023–20,041.Rostron,B.J.,To´th,J.,1995.Wide-spread underpressures in the Cretaceous formations of west-central Alberta,Canada.AAPG Annual Convention,Houston,TX,p.83.Wright,G.N.,McMechan,M.E.,Potter,D.E.G.,1994.Structure and architecture of the Western Canada Sedimentary Basin.In: Mossop,G.D.,Shetsen,I.(compilers),Geological Atlas of the Western Canada Sedimentary Basin,pp.25–40(chap.3).E.B.Bekele et al./Journal of Geochemical Exploration69–70(2000)601–605605。

高级英语(第三版)第二册第十三课 The Mansion A Subprime Parable

• His bestselling books include The Big Short: Inside the Doomsday Machine, Liar's Poker, The New New Thing, Moneyball: The Art of Winning an Unfair Game, The Blind Side: Evolution of a Game, Panic, Home Game: An Accidental Guide to Fatherhood and Boomerang.
Negative Effects on Economy
●Stock market declines further reduce household wealth
Liquidity Crunch （不足）
for Businesses
Bank Failures
Bank Capital Levels Depleted
…the result is a forest of For Sale signs and an army of workers…distances
As a result , lots of houses were put up for sale but very few people want to buy houses, and so a large group of workers had to travel long distances back and forth between home and work place. Forest: Something resembling a forest, especially in profusion and lushness. Army: a great multitude. Commute: to travel back and forth regularly.

刘颖会外文翻译原文及译文

大连民族学院国际商学院英文翻译2007级毕业论文外文翻译资料Microfinance's Latest Growing Pains小额信贷业的发展阵痛《Knowledge Wharton》February 2nd 2011《沃顿知识》杂志 2011年2月2日译者：刘颖会大连民族学院国际商学院国际经济与贸易072班2011年6月小额信贷业发展阵痛近期的小额信贷危机源于印度南部城市安得拉邦，当地过度负债、暴力催款和借款者被迫自杀等问题引发了民众对小额信贷行业的广泛指责，并强烈呼吁政府加强监管。

10月，印度政府对损害信贷、强行控制回款天数并拖累印度最大的盈利性小额信贷公司SKS股价暴跌的小额信贷机构实施管制。

1月19日，印度储备银行发布Malegam委员会报告，建议对印度小额信贷机构施加一系列新的监管措施，包括设置利率上限、贷款限额以及对借款人的收入进行规定。

有些观察家对此表示欢迎，而悲观人士则认为此举难以避免信贷紧缩和行业崩溃。

尽管现在要分析行业前景还为时尚早，但安得拉邦的危机着实引发了民众对全球小额信贷行业的热烈讨论和深刻反省。

近期在沃顿阿瑞斯高级管理教育学院小额信贷管理培训班上，讨论的焦点集中在过度信贷、高速的行业增长以及如何在追求利润的同时更好地实现小额信贷的设立宗旨。

小额信贷业经历了一场由坏账“大地震”所引发的“痛苦的觉醒”，26名来自全球各地的社会财富计划参与者之一Kamran Azim在一堂主题为小额信贷业的增长与可持续发展的讨论中如此比喻道。

Azim是创立于1996年的巴基斯坦拉合尔小额信贷机构Kashf 基金的运营总监。

他指出，过去20到30年间，小额信贷的方式方法几乎都没有发生过变化。

但现在，突然之间，这个行业经历了一场地震。

正如该培训计划中一门课程的导言所说：“面对不断加速的变革，人们趋向于依赖传统的方式进行商业发展。

然而，正是在这样的时刻，创新方显得尤为重要。

”此外，几名学员也指出，小额信贷行业必须在兼顾客户需求的同时通过创新的方式来巩固发展。

先天性心脏病的节段分析法

It is important to detect any thoracic or pulmonary anomalies that might lead to displacement of the heart.
Cardiac dextroposition due to right lung hypoplasia after a right diaphragmatic hernia repair
➢ Assessment of Cardiac Anatomy ➢ Assessment of Connecting Segments ➢ Assessment of Associated Malformations
Step 1: Determining the Visceroatrial Situs
right main stem bronchus; the right pulmonary artery lies in front of the right bronchus (eparterial bronchial position); ➢ a left-sided bilobed lung with a more distal origin of the upper lobe bronchus; the left pulmonary artery crosses above the left bronchus (hyparterial bronchial position).
Segmental Approach to Imaging of Congenital Heart Disease
杜倩妮 20பைடு நூலகம்9.09
The segmental approach, which is widely used in the imaging workup of congenital heart disease, consists of a three-step evaluation of the cardiac anatomy.

海洋放线菌

Contents 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Actinomycetes in the marine environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Role of actinomycetes in marine environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rare actinomycetes and selective isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Molecular approaches to search for indigenous marine actinomycetes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Different genera of marine actinomycetes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Marine streptomycetes – a boundary microorganism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fermentation process for metabolites production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Secondary metabolites from actinomycetes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Novel/new metabolites from marine actinomycetes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00 00 00 00 00 00 00 00 00 00 00 00 00

Reply to ``Proof of the Gauge Independence of the Conformal Anomaly of Bosonic String in th

arXiv:h ep-th/971175v111N ov1997TUW 97-17Reply to “Proof of the Gauge Independence of the Conformal Anomaly of Bosonic String in the Sense of Kraemmer and Rebhan”Ulrike Kraemmer and Anton Rebhan Institut f¨u r Theoretische Physik,Technische Universit¨a t Wien,Wiedner Hauptstr.8–10,A-1040Vienna,Austria February 1,2008The standard approach to covariant quantization of string theory chooses the conformal gauge,which in the critical dimension permits to eliminate the world-sheet metric as a dynamical variable[1].The gauge independence of the conformal anomaly,which determines the critical dimension,has been investigatedﬁrst in Ref.[2],but only for algebraic gauges.In Ref.[3],the world-sheet anomalies were explicitly calculated for the harmonic gauge, which appeared to be of particular interest because of a vanishing ghost-number anomaly.The conformal anomaly on the other hand remained un-changed as expected.In Ref.[4]the present authors have conﬁrmed these results,but have shown that the eliminated ghost-number anomaly has just been shifted to an analogous number-current anomaly for the now dynamical world-sheet metric;the sum of the ghost-number and the so-called Lagrange-multiplier anomalies turned out to be gauge independent.The gauge inde-pendence of the conformal anomaly was also veriﬁed in Refs.[5,6,7],which considered the background-covariant harmonic gauge,and in Refs.[8,4], where non-background-covariant de Donder gauges were used.In Ref.[9]we have reviewed and extended the explicit calculations of the various world-sheet anomalies and have given a simple proof of the observed gauge independences based on BRS symmetry.In a more general frame-work,the gauge independence of anomalies was subsequently conﬁrmed in Refs.[10,11].Some years later,a seemingly contradictory result was published by Abe and Nakanishi[12],who claimed that in non-conformal gauges the confor-mal anomaly was undetermined due to ambiguities in the deﬁnition of the energy-momentum tensor.1Although later Ref.[13]has pointed out that their ambiguity disappears if one refrains from restricting to aﬂat back-ground prematurely,in Refs.[14,15]Abe and Nakanishi have recently ques-tioned the previous works that showed the gauge independence of world-sheet anomalies.In particular they claimed that the explicit proof in Ref.[9] was based on false assumptions and therefore wrong.(Not trusting the more general arguments of Refs.[10,11],they presented an alternative proof which is however so restricted that they cannot even“compare two gauges which have diﬀerent Feynman rules”.)In Ref.[9]we have considered diﬀeomorphism and Weyl gauge conditionsof the formF mni[ˆg]h mn=0,Ωmn[ˆg]hmn=0,i,m,n=0,1(1)where h mn=g mn−ˆg mn withˆg being a classical backgroundﬁeld.Imposing these gauge conditions by Lagrange multipliers b i and b,respectively,one ﬁnds that h mn and(b i,b)ﬁelds have only mixed propagators.As a conse-quence,the one-loop eﬀective action is exact and the gauge-ﬁxed action can be linearized with respect to the quantum metricﬁeld h mn.Correspondingly, the BRS symmetry can be linearized,which moreover implies abelianization.As is well known,while anomalies arise only in the context of renor-malization,they are contained already in the regularized eﬀective actionΓ, which is a functional of the background metricﬁeldˆg mn.Local contribu-tions to the latter can be changed by renormalization,but non-local ones can ing this freedom to restore any diﬀeomorphism invariance that a particular regularization scheme may have violated[16],the eﬀective ac-tion is proportional to d2x√In order to determine the proportionality factor inΓ[ˆg]∝ d2x2It is called harmonic gauge in Ref.[17],but in the terminology of our Ref.[9]we have reserved this term for the background-covariant version.3References[1]A.M.Polyakov,Phys.Lett.B103(1981)207[2]S.Hwang and R.Marnelius,Nucl.Phys.B272(1986)389[3]D.W.D¨u sedau,Phys.Lett.B188(1987)51[4]A.Rebhan and U.Kraemmer,Phys.Lett.B196(1987)477[5]torre,Nucl.Phys.B297(1988)171[6]D.Z.Freedman,torre and K.Pilch,Nucl.Phys.B306(1988)77[7]V.Del Duca,L.Magnea,P.van Nieuwenhuizen,Int.J.Mod.Phys.A3(1988)1081[8]L.Baulieu and A.Bilal,Phys.Lett.B192(1987)339[9]U.Kraemmer and A.Rebhan,Nucl.Phys.B315(1989)717[10]W.Kummer,Phys.Lett.B231(1989)53;O.Piguet,D.Schwarz and M.Schweda,Phys.Lett.B245(1990)393 [11]W.Kummer,“Gauge independence of anomalies”,in Fields and Par-ticles,eds.H.Mitter and W.Schweiger(Springer-Verlag,1990)pp.231–253;Acta Phys.Polonica22(1991)37[12]M.Abe and N.Nakanishi,Mod.Phys.Lett.A7(1992)1799[13]W.M¨o dritsch,Mod.Phys.Lett.A9(1994)241(hep-th/9308074)[14]M.Abe and N.Nakanishi,preprint RIMS-1161(hep-th/9710131)[15]M.Abe and N.Nakanishi,preprint RIMS-1164(hep-th/9710132)[16]A.Rebhan,U.Kraemmer and R.Knienider,Phys.Rev.D39(1989)3625[17]T.Takahashi,Prog.Theor.Phys.95(1996)995(hep-th/9512015)4。

成人朗格汉斯细胞组织细胞增生症临床特征以及预后因素分析

!临床研究与经验！doi：10.16252/ k i.issn1004-0501-2021.02.007论著成人朗格汉斯细胞组织细胞增生症临床特征以及预后因素分析凌彦歿，李亚荣，龚玉萍(四川大学华西医院血液内科，四川成都610041)【摘要】目的分析成人朗格汉斯细胞组织细胞增生症（L C H)的临床特征和潜在的预后因素。

方法回顾性纳入我院血液科2007年至2017年确诊的53例成人L C H患者，收集临床基本资料、疗效及预后数据，分析患者不同临床特点对疾病疗效及预后的影响。

结果53例成人L C H患者中男女性别比为2.8: 1，发病年龄中位数为34岁。

单系统单病灶LCH(SS-LCH)缓解中位时间为83个月，单系统多病灶LCH(SM-LCH)、多系统LCH(M S-LCH)缓解中位时间分别为36个月、40个月，明显低于SS-LCH(2 = 0. 004)。

相关性分析提示L C H受累范围与LD H值呈正相关（2= 0. 026)。

多因素分析提示，与SS-LCH患者相比，MS-LCH和SM-LCH疾病复发风险更高（2=0.047);而初始选择联合治疗方案（手术联合放疗）显著增加L C H复发风险（2 = 0.022)。

在排除年龄因素下，复发（2 =0.047)和血清L D H高水平（2=0.023)是LCH治疗效果不佳的危险因素。

结论L C H以男性为主，起始治疗采用联合方案以及疾病累及范围广是L C H复发的独立危险因素。

复发患者和高血清L D H水平是L C H治疗效果不佳的主要影响因素。

【关键词】朗格汉斯细胞组织细胞增生症；临床特征;预后因素【中图分类号】R551. 1【文献标志码】 A 【文章编号】1004 6501(2021)02-013765Clinical Features and Potential Prognostic Factors of Langerhans Cell Histiocytosis in A dult. Ling Yantao, Li Yarong，Gong Yuping. Department o f Hematology，West China Hospital，Sichuan University，Chengdu，Sichuan 610041，China.[A b stract] Objective To analyze the clinical features and potential prognostic factors of adult Langerhans cell histiocyto-sis( LCH) . M ethods We retrospectively included 53 adult patients with LCH diagnosed from the department of hematology，westChina hosjDital，Sichuan university from 2007 to 2017. Basic clinical data，eficacy and prognostic data were collected，and the impact of diferent clinical characteristics of patients on eficacy and prognosis was analyzed. Results The sex patients was 2. 8 •1，in which median age of was 34 years. The median remission time for single-system months，and the median remission time for single-system multifocal LCH( SM-LCH) and multi-system LCH( MS-LCH) were 36months and 40 months，respectively，who were significantly lower than SS-LCH( 2=0. 004). Correlation analysis suggested thatthe involvement of LCH was positively correlated witli the LDH value( 2- 0. 026 ). Multivariate analysis suggested that comparedwith SS-LCH，MS-LCH and SM-LCH h ad a higher risk of recurrence(2= 0.047); while the initial combination therapy optionsignificantly increased the risl^ of LC H recurrence ( 2 - 0. 022 ) . When excluding age，disease recurrence ( 2-0. 047 ) and high serum LDH levels(2 -0. 023) were risl^ factors for poor efficacy of LCH. Conclusion Adult LCH is predominantly male. The combination therapy in initial treatment and a wide involvement of LCHare an independent risl^ factor f or rence and high serum LDH levels can reduce the efficacy of LCH.[Key w ords] langerhans cell histiocytosis; clinical features；prognostic factors朗格汉斯细胞组织细胞增生症（Langerhans cell histiocytosis，LCH)是一种异常朗格汉斯细胞（LCs)克隆性增生的罕见疾病，均表达CD1a、CD207。

Academia_and_the_Market

News that the 2012 Nobel Prize in Literature was awarded to Chinese writer Mo Y an was understandably considered a triumph marked by wide celebrations in China thatcaught publishers off-guard. Mo’s novels instantly sold out at every major bookstore. After five days of empty shelves, Shanghai Book City, the largest bookstore in Shanghai, eventually received 8,000 copies of Mo Yan’s Novel Collection, published hurriedly by Shanghai Lit-ACADEMIA and the MARKETText by Chong YatuA display especially for Mo Yan’s work becomes the highlight of a bookstore. CFPerature and Art Publishing House due to the spike in demand. Because of the time crunch, the publisher even failed to tag the cover with coveted promotional words “Nobel Prize Laureate in Literature.”Mo is recognized as an inflential figure in modern Chinese literature, but his work performed modestly in both publication and circulation due to the au-thor’s preference for heavy topics and complex ideas embedded in his descriptions. As a result, domestic publishers were never willing to risk financial futures on extensive promotion and publication of his work. Shanghai Book City, for example, retained a monthly stock of only a hundred copies of Frog, one of Mo’s best-selling novels.This provides a window into the Chinese publish-ing industry, which seems hesitant to promote deeperliterature that questions reality. Readers of heavier lit-erature have steadily decreased, so publishers are not optimistic about the market potential of this genre of book. On the other hand, such work’s lofty position in literary circles makes it hard to abandon. So, differ-ent sectors of the industry have made different choices with critically-acclaimed literature.Profit-Driven PublishersMai Jia is a celebrated Chinese writer who has seen rocketing market value in recent years after sev-eral of his books were adapted into popular TV se-ries. In 2010, he revealed a personal anecdote: Y ears ago, when he had just begun writing Wind Whisperer, which would later be adapted into another TV drama, a publisher visited his home three times, offering the astronomical figure of 5 million yuan for the rights to the book, but was rejected each time. Mai couldn’t un-derstand why the publisher was offering such a high price without even reading the manuscript. He sur-mised that some publishers were so profit-driven that they prefer mediocre work by a famous writer to an excellent book by an unknown author.Mai’s experience testifies to a phenomenon in con-temporary Chinese publishing. Fierce market compe-tition has resulted in a tendency of some publishers to seek only profits, ignoring social value. Therefore, “pure” literature, sated with critical realism and socialvalue, has become marginalized to some extent. In or-der to improve marketing, they brainstorm a plethoraof tactics. In 2009, when Mo Yan’s full-length novelFrog was released in Shanghai, the publishing houseinvited celebrity novelist Guo Jingming, who wasborn in the 1980s, to the ceremony, hoping to attractthe younger writer’s fans to Mo’s work. The market-ing move truly embarrassed Mo, who had alreadyachieved fame before Guo was born. He didn’t mincewords when stating his disgust that sales of Frog reliedon help from Guo. However, the tastes of the currentmarket pressure publishers to treat academic literatureas such.Many Chinese literary heavyweights have sighed atthe state of the craft. Some critics point out that exter-nal factors are responsible for the fact that most cur-rent Chinese bestsellers have little literary value, andsome even contain negative information that couldmislead the public. Since the demands of the markethave largely replaced academic literary criteria, manywriters believe both the number of high-caliber writersand the quality of Chinese writing are in a free fall. Struggling JournalsIn China, authors traditionally cherish literaryjournals passionately. Many literaryheavyweightsMo Yan’s workdisplayed atFrankfurt BookFair 2012.ICearned fame through periodical magazines, which they believe contribute significantly to the survival and de-velopment of Chinese literature.Today, however, due to dwindling readership, many Chinese literary journals are facing hard times. Pressured by financial difficulties, the renowned liter-ary magazine Master began accepting paid articles, a move which ultimately resulted in its closure and reor-ganization.Tightly-budgeted literary magazines like Master once abounded. According to Zhang Shengyou, sec-retary of the Secretariat of Chinese Writers Associa-tion, China has more than 9,000 journals of various types, and 10 percent are literary magazines, which are mostly endangered.In contrast, the literature boom of the 1980s and 90s remains a crystal clear memory for many Chinese writers. Chen Dongjie, deputy editor-in-chief of Octo-ber magazine, describes the period as a “crazy golden age” for writers and readers alike. “Back then, liter-ary journals were almost positioned as the mainstream media,” he recalls. “Writers, like today’s entertainment stars, developed loyal followings, and magazines, like iPhones today, were snapped up immediately when they hit newsstands. Chinese language and literature departments in universities only admitted top scoring students.” As the public’s reading interests change, lit-erary journals have been left with little demand from the market.Despite the difficult situation, some journals aren’t ready to throw in the towel. In their eyes, a nation’s ac-ademic literature is iconic, responsible for promoting, representing, and developing culture while protecting literary art from commercialization. Qiu Huadong, assistant to the editor-in-chief of People’s Literature, once said, “We will never surrender to market, but will stand by high-class literature. Our goal is to improve this strategy and attract more high-end readers to fall in love with pure literature.”To this end, some magazines are attempting to expand the influence of pure literature and elevate public aesthetic taste. In May 2010, Harvest , a liter-ary magazine with a monthly circulation of 100,000,raised its contribution fee to 400 - 500 yuan for everyWhen Red Sorghum , an adaptation of Mo Yan’s novel, was filmed, the female lead Gong Li (center) posed with the author and his family.When Mo Yan’s full-length novelFrog was re-leased, the pub-lishing house invited popular young writer Guo Jingming to the ceremony to helppublicity. CFP1,000 characters, drawing considerable attention. Oc-tober, another example, regularly organizes meetings between authors and readers to facilitate communi-cation. However, just how much such moves help the academic literature industry is unknown.Newspaper DilemmasChinese literature enthusiasts have likely noticed that except for major newspapers like People’s Daily and Xinmin Evening News , which still publish literary articles, many regional papers have reshaped or even cut their literature sections.Newspapers’ current attitudes towards literature sharply contrast those at the end of last century, when authors and literary works were the highlight of most Chinese newspapers. Newer papers established special columns devoted to publishing novels and poems. Lit-erary content was regarded as a top criterion in judg-ing the quality of a newspaper. In that era, a wealth of outstanding essays and novels were immortalized through the pages of newspapers, such as A Bitter Journey of Culture by Yu Qiuyu, Ordinary WorldbyLu Yao, and Brothers by Yu Hua.Some industry experts attribute the dramatic change to the contrast between the patient pace of lit-erature and the “fast facts” tone of newspapers. When reading preferences of a society as a whole change, market-sensitive newspapers have to adjust. Others hy-pothesize about the cold relationship between writers and media, suggesting that academic literary masters are rarely interested in participating in promotional campaigns, whereas other writers are not really pre-ferred by media and readers. As a result, newspapers gradually lost their literary flavor.Eminent writer Wang Meng strongly called for the revival of literature in newspapers, asserting that “Newspapers’ literature editions should capitalize ontheir advantages, unite authors, discover new talent, and create a land where literature can flourish.”Mo Yan’s Nobel Prize in Literature has undoubt-edly reignited Chinese interest in literature and renewed newspapers’ taste for literature as well. In addition tomany pages covering Mo’s biography and work, some domestic newspapers have already announced plans to restore or expand their literature editions. Mo Yan (right)and writer WangAnyi attend a symposiumthemed, “Writing: The Most For-midable Resis-tance.” A greatnumber of Chi-nese writers havetaken action tosave academicliterature fromdecline. CFP。

2023年新版英语专四真题及答案

英语专业四级真题及答案III. 语言知识：11. ___B_____ combination of techniques authors use, all stories---from the briefest anecdotes to the longest novels ----have a plot.A. RegardingB. Whatever.C. In so far asD. No matter12. She followed the receptionist down a luxurious corridor to a closed door, ____B______ the women gave a quick knock before opening it..A. whereinB. on whichC. but whenD. then13. Ms Ennab is one of the first Palestinian ______C____ with seven years’ racing experience.A. woman driversB. women driverC. women driversD. woman driver14. “I wondered if I could have a word with you.”The past tense in the sentence refers to a __B___.A. past event for exact time referenceB. present event for tentativenessC. present event for uncertaintyD. past event for politeness15. “If I were you, I wouldn’t wait to propose to her.” The subjunctive mood in the sentence is used to ____D______.A. alleviate hostilityB. express unfavorable feelingsC. indicate uncertaintyD. make a suggestion16. “It’s a shame that the city official should have gone back on his word.” The modal auxiliary SHOULD express __B_____.A obligationB disappointmentC future in the past D. tentativeness17. Timothy Ray Brown, the first man cured of HIV, initially opted against the stem cell transplantation that _____D______ history.A. could have later madeB. should have made laterC. might make laterD. would later make18. Some Martian rock structures look strikingly like structures on Earth that are known ___C___by microbes.A. having been createdB. being createdC. to have been createdD. to be created19. At that moment, with the crowd watching me, I was not afraid in the ordinary sense, as ______ if I ____A_______alone.A. would have been …had beenB. should be … had beenC. could be … wereD. might have been… were20. You must fire __C____ incompetent assistant of yoursA. theB. anC. thatD. whichever21. Some narratives seem more like plays, heavy with dialogue by which writers allow their __A___to reveal themselves.A. charactersB. characteristicsC. charisma D characterizations22. If you intend to melt the snow for drinking water, you can ___D_____ extra purity by running it through a coffee filter.A. assureB. insureC. reassureD. ensure23. The daisy-like flowers of chamomile have been used for centuries to ___B____anxiety and insomnia.A. declineB. relieve C quench D suppress24. Despite concern about the disappearance of the album in popular music, delivered a great crop of album ___C_______.A. publications B appearances C. releases D. presentations25. The party’s reduced vote in the general election was ___C______of lack of support for its policies.A. revealingB. confirmingC. indicativeD. evident26. He closed his eyes and held the two versions of La Mappa to his mind’s __B______ to analyzetheir differences.A. vision B eye C. view D. sight27. Twelve pupils were killed and five ___A_____injured after gunmen attacked the school during lunchtime.A. criticallyB. enormouslyC. greatlyD. hard28. A 15-year-old girl has been arrested ___C_____ accusations of using Instagram to anonymously threaten her high-school.A. overB. withC. onD. for29. It was reported that a 73-year-old man died on an Etihad flight __D______to Germany from Abu Dhabi.A. boundedB. bindedC. boundaryD. bound30. It’s ____B_____ the case in the region; a story always sounds clear enough at a distanced, but the nearer you get to the scene of events the vaguer it becomes.A. unchangeablyB. invariablyC. unalterablyD. immovablyIV. 完形填空：A. alwaysB. barelyC. demiseD. emergenceE. gainedF. implicationsG. leafH. lostI. naturallyJ. objectK. oneL. onlineM. risingN. singleO. valueMILLIONS of people now rent their movies the Netflix way. They fill out a wish list from the 50,000 titles on the company's Web site and receive the first few DVD's in the mail; when they mail each one back, the next one on the list is sent. The Netflix model has been exhaustively analyzed for its disruptive, new-economy（31）implications. What will it mean for video stores like Blockbuster, which has, in fact, started a similar service? What will it mean for movie studios and theaters? What does it show about "long tail" businesses -- ones that combine many niche markets, like those for Dutch movies or classic musicals, into a (32)single large audience? But one othermajor implication has (33)barely been mentioned: what this and similar Internet-based businesses mean for that stalwart of the old economy, the United States Postal Service.Every day, some two million Netflix envelopes come and go as first-class mail. They are joined by millions of other shipments from（34）online pharmacies, eBay vendors, and other businesses that did not exist before the Internet.The（35）demise of "snail mail" in the age of instant electronic communication has been predicted at least as often as the coming of the paperless office. But the consumption of paper keeps （36）rising. It has roughly doubled since 1980. On average, an American household receives twice as many pieces of mail a day as it did in the 1970's.The harmful side of the Internet's impact is obvious but statistically less important than many would guess. People (37) naturally write fewer letters when they can send e-mail messages. To (38) leaf through a box of old paper correspondence is to know what has been _(39) lost i n this shift: the pretty stamps, the varying look and feel of handwritten and typed correspondence, the tangible (40) object that was once in the sender's hands.V. Reading comprehensionSection APassage one（1）When I was a young girl living in Ireland, I was always pleased when it rained, because that meant I could go treasure hunting. What’s the connection between a wet day and a search for buried treasure? Well, it’s quite simple. Ireland, as some of you may already know, is the home of Leprechauns – little men who possess magic powers and, perhaps more interestingly, pots of gold. （2）Now, although Leprechauns are interesting characters, I have to admit that I was more intrigued by the stories of their treasure hoard. This, as all of Ireland knows, they hide at the end of the rainbow. Leprechauns can be fearsome folk but if you can discover the end of the rainbow,they have to unwillingly surrender their gold to you. So whenever it rained, I would look up in the sky and follow the curve of the rainbow to see where it ended. I never did unearth any treasure, but I did spend many happy, showery days dreaming of what I could do with the fortune if I found it.（3）As I got older, and started working, rainy days came to be just another nuisance and my childhood dreams of finding treasure faded. But for some people the dream of striking it lucky never fades, and for a fortunate few, the dream even comes true! Such is the case of Mel Fisher. His dream of finding treasure also began in childhood, while reading the great literature classics “Treasure Island” and “Moby Dick”. However, unlike myself, he chased his dream and in the end managed to become one of the most famous professional treasure hunters of all time, and for good reason. In 1985, he fished up the priceless cargo of the sunken Spanish ship Atocha, which netted him an incredible $400 million dollars!（4）After the ship sank in 1622 off the coast of Florida, its murky waters became a treasure trove of pre cious stones, gold bars and silver coins known as “pieces of eight”. The aptly-named Fisher, who ran a commercial salvaging operation, had been trying to locate the underwater treasure for over 16 years when he finally hit the jackpot! His dreams had come true but finding and keeping the treasure wasn’t all plain sailing. After battling with hostile conditions at sea, Fisher then had to battle in the courts. In fact, the State of Florida took Fisher to court over ownership of the find and the Federal government soon followed suit. After more than 200 hearings, Fisher agreed to donate 20% of his yearly findings for public display, and so now there is a museum in Florida which displays hundreds of the objects which were salvaged from the Atocha.（5）This true story seems like a modern-day fairytale: a man pursues his dream through adversity and in the end, he triumphs over the difficulties - they all live happily ever after, right? Well, not exactly. Archaeologists object to the fact that with commercial salvaging operations likeFisher’s, the objects are sold and dispersed and UNESCO are worried about protecting our underwater heritage from what it describes as “pillaging”.（6）The counter-argument is that in professional, well-run operations such as Fisher’s, ea ch piece is accurately and minutely recorded and that it is this information which is more important than the actual object, and that such operations help increase our wealth of archaeological knowledge. Indeed, as in Fisher’s case, they make history more accessible to people through museum donations and information on web sites.（7）The distinction of whether these treasure hunters are salvaging or pillaging our underwater heritage may not be clear, but what is clear is that treasure hunting is not just inn ocent child’s play anymore but profitable big business. I have learnt that the end of the rainbow is beyond my reach, but in consolation, with just a click of the mouse, I too can have a share in the riches that the Atocha has revealed. As Friedrich Nietzsche so wisely said: “Our treasure lies in the beehive of our knowledge.”41. In Para.4, the phrase “hit the jackpot” means ______according to the text.A. discovered the jackpot.B. found the treasureC. broke one of the objectsD. ran a salvaging operation42. It can be concluded from Paras. 5 and 6 that _________.A. people hold entirely different views on the issueB. UNESCO’s view is different from archaeologists’C. all salvaging operations should be prohibitedD. attention should be paid to the find’s educational value43. How did the author feel about the treasure from the Atocha (Para. 7)?A. She was unconcerned about where the treasure came fromB. She was sad that she was unable to discover and salvage treasure.C. She was angry that treasure hunters were pillaging heritage.D. She was glad that people can have a chance to see the treasure.Passage two（1）PAUL was dissatisfied with himself and with everything. The deepest of his love belonged to his mother. When he felt he had hurt her, or wounded his love for her, he could not bear it. Now it was spring, and there was battle between him and Miriam. This year he had a good deal against her. She was vaguely aware of it. The old feeling that she was to be a sacrifice to this love, which she had had when she prayed, was mingled in all her emotions. She did not at the bottom believe she ever would have him. She did not believe in herself primarily: doubted whether she could ever be what he would demand of her. Certainly she never saw herself living happily through a lifetime with him. She saw tragedy, sorrow, and sacrifice ahead. And in sacrifice she was proud, in renunciation she was strong, for she did not trust herself to support everyday life. She was prepared for the big things and the deep things, like tragedy. It was the sufficiency of the small day-life she could not trust.（2）The Easter holidays began happily. Paul was his own frank self. Yet she felt it would go wrong. On the Sunday afternoon she stood at her bedroom window, looking across at the oak-trees of the wood, in whose branches a twilight was tangled, below the bright sky of the afternoon. Grey-green rosettes of honeysuckle leaves hung before the window, some already, she fancied, showing bud. It was spring, which she loved and dreaded.（3）Hearing the clack of the gate she stood in suspense. It was a bright grey day. Paul came into the yard with his bicycle, which glittered as he walked. Usually he rang his bell and laughed towards the house. To-day he walked with shut lips and cold, cruel bearing, that had something ofa slouch and a sneer in it. She knew him well by now, and could tell from that keen-looking, aloof young body of his what was happening inside him. There was a cold correctness in the way he put his bicycle in its place, that made her heart sink.（4）She came downstairs nervously. She was wearing a new net blouse that she thought became her. It had a high collar with a tiny ruff, making her, she thought, look wonderfully a woman, and dignified. At twenty she was full-breasted and luxuriously formed. Her face was still like a soft rich mask, unchangeable. But her eyes, once lifted, were wonderful. She was afraid of him. He would notice her new blouse.（5）He, being in a hard, ironical mood, was entertaining the family to a description of a service given in the Primitive Methodist Chapel. He sat at the head of the table, his mobile face, with the eyes that could be so beautiful, shining with tenderness or dancing with laughter, now taking on one expression and then another, in imitation of various people he was mocking. His mockery always hurt her; it was too near the reality. He was too clever and cruel. She felt that when his eyes were like this, hard with mocking hate, he would spare neither himself nor anybody else. But Mrs. Leivers was wiping her eyes with laughter, and Mr. Leivers, just awake from his Sunday nap, was rubbing his head in amusement. The three brothers sat with ruffled, sleepy appearance in their shirt-sleeves, giving a guffaw from time to time. The whole family loved a "take-off" more than anything.44. It can be learned from the beginning that Mariam’s attitude toward love between her and Paul is ________.A. indifferentB. desperateC. pessimisticD. ambiguous45. The narration in Para. 3 tells us that Miriam had all the following feelings except _______.A.delightB. expectationC. uncertaintyD. forebearing46. Which of the following statements is correct about the family’s response to Paul’s mockery?A. Only the parents found it entertaining.B. Every member except Marriam was amusedC. The brothers found it hard to appreciate.D. Mariam also thought it was amusingPassage three（1）I’ve written this article and you’re reading it. So we are members of the same club. We’re both literate – we can read and write. And we both probably feel that literacy is essential to our lives. But millions of people all over the world are illiterate. Even in industrialised western countries, such as the UK and the USA, approximately 20% of the population have 'low literacy levels'. But what exactly does that mean?（2）My parents both left school at 14. They could read and write, but except for a quick look at the daily newspaper, reading and writing didn't play a big part in their lives. There were very few books in the house. My mother was amazed because the woman who lived next door always wrote a list of what she needed before she went to the supermarket. Why couldn't she remember? We laughed about that for weeks. Our family didn't write lists! And when I was only 14 years old my father gave me an important letter that he'd written to the bank and asked me to check it for grammar and spelling mistakes. And there were quite a lot. He never usually wrote letters or postcards or even Christmas cards. So when he had to write he wasn't comfortable or confident. Does that mean that my father had a 'low level of literacy'? I don't think so.（3）There are lots of different definitions of literacy. Some experts define it as having the reading and writing skills that you need to be independent in your everyday life. So, for example, if you can read instructions, write a cheque, fill in a form, –anything that you need to do in everyday life – then you are 'functionally literate'.（4）Other people say that you are illiterate if you think that you are illiterate. In other words, if you feel that you can't read or write as well as you would like to.（5）If you live in a society where most people are literate then you will feel ashamed orembarrassed and avoid situations in which you have to read or write. The father of a friend of mine finally admitted to his family that he couldn't read when he was 45 years old. He bought the newspaper every day and pretended to read it - and believe it or not, his family had no idea.（6）We often forget that writing is a recent invention. Many years ago, the word 'literate' meant being able to communicate well in speaking, in other words what we now call 'articulate'. Story telling was an important activity in the past and still is today in some societies. Reading was often a co-operative activity – someone would read aloud to a group, often from a religious text such as the Koran or the Bible.（7）Only a hundred years ago, in the United States, you were considered to be literate if you could sign your name to a piece of paper. It was an important skill. You were not allowed to vote if you couldn't sign the voting register, so literacy was connected with political rights, and many people were excluded from the democratic process.（8）Nowadays we see reading and writing as being connected, but that wasn't so in the past. Many people could read, but not write. Writing was a skilled profession. If you needed something written then you paid an expert to write it for you.（9）And of course, rich and important people have always employed people to write things for them. Important company bosses dictated letters to their secretaries or personal assistants. And now with new computer software you can dictate directly to your computer.（10）Being illiterate can have a big effect on people's lives. For example, a study in the UK showed that people who write and spell badly are seen as careless, immature and unreliable, and often unintelligent. So it is more difficult for them to find jobs, even when reading and writing are not necessary for the work.（11）World-wide statistics show that literacy problems are associated with poverty and a lack of political power. More women than men are illiterate. Illiterate people have worse health, bigger families and are more likely to go to prison. So literacy campaigns must be a good thing. But don'tforget that an illiterate person, or someone with a low level of literacy, isn't necessarily stupid or ignorant – and may not be unhappy at all. Knowledge and wisdom isn't only found in writing.47. Why does the author give two examples in Para 2?A. To show that literacy is interpreted in different ways.B. To show that Father was more literate than Mother.C. To indicate how important reading and writing are.D. To compare the level of literacy between neighbours.48. According to the author, the following are some of the defining features of literacy EXCETT________.A. psyhchologicalB. functionalC. socialD. independent49. Which of the following statements about reading and writing is CORRECT?A. Reading and writing have always been regarded as equally difficult.B. People had to read and write well in order to be allowed to vote.C. Reading often requires more immediate interaction than writing.D. Reading and writing have always been viewed as being connected.50. What do the last two paragraphs mainly focus on ?A. Effects of illiteracy and employment problems.B. Effects of illiteracy and associated problems.C. Effects of illiteracy on one’s personality development.D. Effects of illiteracy on women’s career development.Section B. Short answer questions. (Answer each question with no more than ten words)Passage one.51. what does This in Para. 2 refer to?It refers to the treasure hoard of Leprechauns.52. Why did Fisher have to battle in the courts after he found the treasure (Para. 4)?Because he was sued over ownership of the treasure.Passage two.53.Why did Mariam wear a new net blouse on Sunday afternoon?Because she wanted to attract Paul’s attention.54. What is the meaning of the sentence “…he would spare neither himself nor anybody else” in Para. 5?Everyone, including himself, would become the targets of his mockery.Passage three.55. Explain the meaning of the last sentence of Para. 11 according to the context.Illiterate people may also have knowledge and wisdom.。

人工分子机器

The kind of energy input supplied to make them work The type of movement performed by their components The way in which their operation can be monitored and controlled The possibility to repeat the operation at will and establish a cyclic process The timescale needed to complete a cycle of operation The function performed by the molecular machine
Seminar I
References
1 P. L. Anelli, N. Spencer, J. F. Stoddart et al., J. Am. Chem. Soc. 113, 5133 (1991). 2 J. D. Badjic, V. Balzani, A Credi et al., Science 303, 1845 (2004). 3 Y. Liu, A. H. Flood, P. A. Bonvallet et al., J. Am. Chem. Soc. 127, 9745 (2005). 4 T. R. Kelly, H. D. Silva, R. A. Silva et al., Nature 401, 150 ( 1999). 5 T. R. Kelly, Acc. Chem. Res. 34, 514 ( 2001) .
Seminar I
Linear Artificial Molecular Muscles

Digesting Anomalies An Investment

1.Conceptual Framework
2.Factor Construction
3.Empirical Results
Conceptual Framework
An economic model
• Stochastic general equilibrium model
• Two dates, 0 and 1.
• ROE increases from −0.80% to 5.00% per
quarter.
3.2.1 Earnings momentum (SUE-1) and price momentum (R6-6)
Result:
• 4 significant alphas in the Fama-French model
stronger in small firms than in big firms (e.g., Bernard and Thomas 1990;
Fama and French 2008), we control for size when constructing the
investment and ROE factors. Sorting jointly with size is also standard in
• 3 in the Carhart model
• 1 in the q-factor model
More:
• The q-factor model captures momentum via the
ROE factor (loadings increase from −0.22 to 0.26).
Digesting Anomalies: An

SpillonomicsUnderestimatingRisk

Spillonomics: Underestimating RiskBy DAVID LEONHARDT, New York Times Magazine, Sunday, June 6, 2010, pp. 13-14.In retrospect, the pattern seems clear. Years before the Deepwater Horizon rig blew, BP was developing a reputation as an oil company that took safety risks to save money. An explosion at a Texas refinery killed 15 workers in 2005, and federal regulators and a panel led by James A. Baker III, the former secretary of state, said that cost cutting was partly to blame. The next year, a corroded pipeline in Alaska poured oil into Prudhoe Bay. None other than Joe Barton, a Republican congressman from Texas and a global-warming skeptic, upbraided BP managers for their “seeming indifference to safety and environmental issues.”Much of this indifference stemmed from an obsession with profits, come what may. But there also appears to have been another factor, one more universally human, at work. The people running BP did a dreadful job of estimating the true chances of events that seemed unlikely — and may even have been unlikely — but that would bring enormous costs.Perhaps the easiest way to see this is to consider what BP executives must be thinking today. Surely, given the expense of the clean-up and the hit to BP’s reputation, the executives wish they could go back and spend the extra money to make Deepwater Horizon safer. That they did not suggests that they figured the rig would be fine as it was.For all the criticism BP executives may deserve, they are far from the only people to struggle with such low-probability, high-cost events. Nearly everyone does. “These are precisely the kinds of events that are hard for us as humans to get our hands around and react to rationally,” Robert N. Stavins, an environmental economist at Harvard, says. We make two basic — and opposite — types of mistakes. When an event is difficult to imagine, we tend to underestimate its likelihood. This is the proverbial black swan. Most of the people running Deepwater Horizon probably never had a rig explode on them. So they assumed it would not happen, at least not to them.Ben Bernanke and Alan Greenspan liked to argue, not so long ago, that the national real Similarly,estate market was not in a bubble because it had never been in one before. Wall Street traders took the same view and built mathematical models that did not allow for the possibility that house prices would decline. And many home buyers signed up for unaffordable mortgages, believing they could refinance or sell the house once its price rose. That’s what house prices did, it seemed.On the other hand, when an unlikely event is all too easy to imagine, we often go in the opposite direction and overestimate the odds. After the 9/11 attacks, Americans canceled plane trips and took to the road. There were no terrorist attacks in this country in 2002, yet the additional driving apparently led to an increase in traffic fatalities.When the stakes are high enough, it falls to government to help its citizens avoid these entirely human errors. The market, left to its own devices, often cannot do so. Yet in the case of Deepwater Horizon, government policy actually went the other way. It encouraged BP to underestimate the odds of a catastrophe.In a little-noticed provision in a 1990 law passed after the Exxon Valdez spill, Congress capped a spiller’s liability over and above cleanup costs at $75 million for a rig spill. Even if the economic damages — to tourism, fishing and the like — stretch into the billions, the responsible party is on the hook for only $75 million. (In this instance, BP has agreed to waive the cap for claims it deems legitimate.) Michael Greenstone, an M.I.T. economist who runs the Hamilton Project in Washington, says the law fundamentally distorts a company’s decision making. Without the cap, executives would have to weigh the possible revenue from a well against the cost of drilling there and the risk of damage. With the cap, theycan largely ignore the potential damage beyond cleanup costs. So they end up drilling wells even in places where the damage can be horrific, like close to a shoreline. To put it another way, human frailty helped BP’s executives underestimate the chance of a low-probability, high-cost event. Federal law helped them underestimate the costs.In the wake of Deepwater Horizon, Congress and the Obama administration will no doubt be tempted to pass laws meant to reduce the risks of another deep-water disaster. Certainly there are some sensible steps they can take, like lifting the liability cap and freeing regulators from the sway of industry. But it would be foolish to think that the only risks we are still underestimating are the ones that have suddenly become salient.The big financial risk is no longer a housing bubble. Instead, it may be the huge deficits that the growth of Medicare, Medicaid and Social Security will cause in coming years — and the possibility that lenders will eventually become nervous about extending credit to Washington. True, some economists and policy makers insist the country should not get worked up about this possibility, because lenders have never soured on the United States government before and show no signs of doing so now. But isn’t that reminiscent of the old Bernanke-Greenspan tune about the housing market?Then, of course, there are the greenhouse gases that oil wells (among other things) send into the atmosphere even when the wells function properly. Scientists say the buildup of these gases is already likely to warm the planet by at least three degrees over the next century and cause droughts, storms and more ice-cap melting. The researchers’ estimates have risen recently, too, and it is also possible the planet could get around 12 degrees hotter. That kind of warming could flood major cities and cause parts of Antarctica to collapse.Nothing like that has ever happened before. Even imagining it is difficult. It is much easier to hope that the odds of such an outcome are vanishingly small. In fact, it’s only natural to have this hope. But that doesn’t make it wise.David Leonhardt is an economics columnist for The Times and a staff writer for the magazine.。

The Wombat A Large and Burrowing Marsupial

The Wombat A Large and Burrowing Marsupial The wombat is a large and burrowing marsupial that is native to Australia. It is a unique animal that has captured the hearts of many people around the world. The wombat is known for its sturdy build, powerful legs, and sharp claws, which it uses to dig extensive burrow systems in the ground. In this essay, we will explore the wombat from different perspectives, including its physical characteristics, behavior, habitat, and conservation status.The physical characteristics of the wombat are what make it such a fascinating animal. It is a sturdy animal that can weigh up to 80 pounds and reach a length of up to 3 feet. Its body is covered in thick fur that protects it from the harsh Australian climate. Wombats have short, powerful legs that are designed for digging and moving through rough terrain. Their front paws have sharp claws that they use to dig burrows and for defense against predators. Wombats also have strong jaws and teeth that allow them to chew tough vegetation.The behavior of the wombat is also unique. Wombats are mostly solitary animals that are active at night. They spend most of their time in their burrows, which they dig using their powerful claws. Wombats have a complex social structure that is based on a hierarchy of dominance. Dominant males have larger territories and access to more resources than subordinate males. Wombats are herbivores that feed on a variety of vegetation, including grasses, roots, and bark.The habitat of the wombat is mainly in Australia, where it is found in a variety of habitats, including forests, grasslands, and scrublands. Wombats are most commonly found in the southeastern part of Australia, where the climate is suitable for their survival. They are also found on some of the offshore islands of Australia. The wombat's burrow system is an important part of its habitat, providing shelter from predators and the harsh Australian climate.The conservation status of the wombat is of concern, with two of the three species listed as vulnerable or endangered. The Northern hairy-nosed wombat is one of the rarestmammals in the world, with only around 200 individuals remaining in the wild. Habitat loss, disease, and predation by introduced predators are the main threats to the survival of the wombat. Conservation efforts are underway to protect the wombat and its habitat, including the establishment of protected areas and efforts to control introduced predators.In conclusion, the wombat is a unique and fascinating animal that has captured the hearts of many people around the world. Its physical characteristics, behavior, habitat, and conservation status are all important aspects of understanding this remarkable creature. As we continue to learn more about the wombat, we can work to protect it and ensure that it continues to thrive in its natural habitat.。

托福阅读句子简化题型及答案

托福阅读句子简化题型及答案托福阅读中词汇题是重要题型之一。

根据托福阅读题型不同来进行专项练习，是短期提高托福阅读能力的有效方法。

那么，在以下内容中，我们就为大家带来一系列的托福简化题内容汇总希望能为大家的备考带来帮助。

托福阅读句子简化题：Early Cinema【Paragraph 2】These Kinetoscope arcades were modeled on phonograph parlors, which had proven successful for Edison several years earlier. In the phonograph parlors, customers listened to recordings through individual ear tubes, moving from one machine to the next to hear different recorded speeches or pieces of music. The Kinetoscope parlors functioned in a similar way. Edison was more interested in the sale of Kinetoscopes (for roughly $1,000 apiece) to these parlors than in the films that would be run in them (which cost approximately $10 to $15 each). He refused to develop projection technology, reasoning that if he made and sold projectors, then exhibitors would purchase only one machine-a projector-from him instead of several. (Early Cinema) Which of the sentences below best expresses the essential information in the highlighted sentence from the passage? Incorrect answer choices change the meaning in important ways or leave out essential information.○Edison was more interested in developing a variety of machines than in developing a technology based on only one.○Edison refused to work on projection technology because he did not think exhibitors would replace their projectors with newer machines.○Edison did not want to develop projection technologybecause it limited the number of machines he could sell.○Edison would not develop projection technology unless exhibitors agreed to purchase more than one projector from him.托福阅读句子简化题答案：3托福阅读句子简化题：Desert Formation【Paragraph 10】The extreme seriousness of desertification results from the vast areas of land and the tremendous numbers of people affected, as well as from the great difficulty of reversing or even slowing the process. Once the soil has been removed by erosion, only the passage of centuries or millennia will enable new soil to form. In areas whereconsiderable soil still remains, though, a rigorously enforced program of land protection and cover-crop planting may make it possible to reverse the present deterioration of the surface. (Desert Formation)Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.○Desertification is a significant problem because it is so hard to reverse and affects large areas of land and great numbers of people.○Slowing down the process of desertification is difficult because of population growth that has spread over large areas of land.○The spread of deserts is considered a very serious problem that can be solved only if large numbers of people in various countries are involved in the effort.○Desertification is extremely hard to reverse unless thepopulation is reduced in the vast areas affected.托福阅读句子简化题答案：1托福阅读句子简化题：The Origins of Cetaceans【Paragraph 5】An even more exciting find was reported in 1994, also from Pakistan. The now extinct whale Ambulocetus natans ("the walking whale that swam") lived in the Tethys Sea 49 million years ago. It lived around 3 million years after Pakicetus but 9 million before Basilosaurus. The fossil luckily includes a good portion of the hind legs.The legs were strong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea. The whale retained a tail and lacked a fluke, the major means of locomotion in modern cetaceans. The structure of the backbone shows, however, that Ambulocetus swam like modern whales bymoving the rear portion of its body up and down, even though a fluke was missing. The large hind legs were used for propulsion in water. On land, where it probably bred and gave birth, Ambulocetus may have moved around very much like a modern sea lion. It was undoubtedly a whale that linked life on land with life at sea.(The Origins of Cetaceans)Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.○Even though Ambulocetus swam by moving its body up and down, it did not have a backbone.○The backbone of Ambulocetus, which allowed it to swim, provides evidence of its missing fluke.○Although Ambulocetus had no fluke, its backbone structureshows that it swam like modern whales.○By moving the rear parts of their bodies up a nd down, modern whales swim in a different way from the way Ambulocetus swam.托福阅读句子简化题答案：3托福阅读句子简化题：highlighted sentence【Paragraph 1】Although we now tend to refer to the various crafts according to the materials used to construct them—clay, glass, wood, fiber, and metal—it was once common to think of crafts in terms of function, which led to their being known as the "applied arts." Approaching crafts from the point of view of function, we can divide them into simple categories: containers, shelters and supports. There is no way around the fact that containers, shelters, and supports must be functional. The applied arts are thus bound by the laws of physics, which pertain to both the materials used in their making and the substances and things to be contained, supported, and sheltered. These laws are universal in their application, regardless of cultural beliefs, geography, or climate. If a pot has no bottom or has large openings in its sides, it could hardly be considered a container in any traditional sense. Since the laws of physics, not some arbitrary decision,have determined the general form of applied-art objects, they follow basic patterns, so much so that functional forms can vary only within certain limits. Buildings without roofs, for example, are unusual because they depart from the norm.However, not all functional objects are exactly alike; that is why we recognize a Shang Dynasty vase as being different from an Inca vase. What varies is not the basic form but the incidental details that do not obstruct the object's primary function.Which of the following best expresses the essential information in the highlighted sentence? Incorrect answer choices change the meaning in important ways or leave out essential information. ( Applied Arts and Fine Arts)○Functional applied-art objects cannot vary much from the basic patterns determined by the laws of physics.○The function of applied-art objects is determined by basic patterns in the laws of physics.○Since functional applied-art objects vary only within certain limits, arbitrary decisions cannot have determined their general form.○The general form of applied-art objects is limited by some arbitrary decision that is not determined by the laws of physics.托福阅读词汇题答案：1。

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a r X i v :a s t r o -p h /0605269v 1 10 M a y 2006Anomalies in the low CMB multipoles and extended foregroundsL.Raul Abramo ∗Instituto de F´ısica,Universidade de S˜a o PauloCP 66318,CEP 05315-970S˜a o Paulo,BrazilLaerte Sodr´e Jr.†Departamento de Astronomia,Instituto Astronˆo mico e Geof´ısico,Universidade de S˜a o PauloRua do Mat˜a o,1226–05508-090S˜a o Paulo,BrazilCarlos Alexandre Wuensche ‡Divis˜a o de Astrof´ısica,Instituto Nacional de Pesquisas Espaciais Av.dos Astronautas,1.758,CEP 12227-010,S˜a o Jos´e dos Campos,Brazil (Dated:February 5,2008)We discuss how an extended foreground of the cosmic microwave background (CMB)can account for the anomalies in the low multipoles of the CMB anisotropies.The distortion needed to account for the anomalies is consistent with a cold spot with the spatial geometry of the Local Supercluster (LSC)and a temperature quadrupole of order ∆T 22≈50µK 2.If this hypothetic foreground is subtracted from the CMB data,the amplitude of the quadrupole (ℓ=2)is substantially increased,and the statistically improbable alignment of the quadrupole with the octopole (ℓ=3)is substantially weakened,increasing dramatically the likelihood of the “cleaned”maps.By placing the foreground on random locations and then computing the likelihood of the cleaned maps we can estimate the most likely place for this foreground.Although the 1-year WMAP data clearly points the location of this hypothetical foreground to the LSC or its specular image (i.e.,the vicinity of the poles of the cosmic dipole axis),the three-year data seems to point to these locations as well as the north ecliptic pole.We show that this is consistent with the symmetries of the cosmic quadrupole.We also discuss a possible mechanism that could have generated this foreground:the thermal Sunyaev-Zeldovich eﬀect caused by hot electrons in the LSC.We argue that the temperature and density of the hot gas which are necessary to generate such an eﬀect,though in the upper end of the expected range of values,are marginally consistent with present observations of the X-ray background of spectral distortions of the CMB.PACS numbers:98.80.-k,98.65.Dx,98.70.Vc,98.80.Es I.INTRODUCTION The cosmic microwave background (CMB)anisotropies have been measured with very high accuracy by WMAP [1,2].Such a barrage of new data seldom brings only conﬁrmation of known theories and mechanisms,and WMAP is no exception:lack of higher correlations [3]and some curious correlations between large-scale anisotropies are some of the most intriguing questions that have been raised by the WMAP data.In particular,two problems have beenpointed with present CMB observations,using a wide variety of data,methods,maps and sky-cuts:ﬁrst,that the quadrupole (ℓ=2)has a lower-than-expected signal [4,5,6].Second,that the quadrupole and octopole (ℓ=3)present an unexpectedly high degree of alignment [4,7,8,9,10,11,12,13].The combined statistics of these eﬀects implies that our CMB sky is only within the ∼0,01%of randomly-generated maps with such anomalous quadrupole and octopole.It is important to note,ﬁrst,that these large-angle anomalies were already present in the COBE data [14],and they were conﬁrmed by WMAP both in the 1-year and in the 3-year data releases [1,2].Second,even though the amplitude of the octopole C 3has increased in the three-year compared to the ﬁrst-year WMAP data,the statistical relevance of the deviant multipoles ℓ=2and ℓ=3has remained practically unchanged in the newly released three-year WMAP data [1],whereas the outliers of the ﬁrst-year data [2]around ℓ≈20,ℓ≈40and ℓ≈200have either disappeared or become much less of a source of concern in the 3-yeardata.These large-angle anomalies have motivated many ingenious explanations,such as compact topologies[15,16,17],a broken or supressed spectrum at large scales[18]and oscillations superimposed on the primordial spectrum of density ﬂuctuations[19].When the low value of the quadrupole is combined with the alignment of the directions deﬁned by these two multipoles(their”normal planes”–see[4,7,8,9,10,11,20]),the overall chance of such a statistical ﬂuctuation is approximately0.005%-0.02%depending on the map and on the mask–i.e.,only about one in10000 randomly generated models have a lower C2and a more aligned quadrupole and octopole than the observed CMB sky.Asﬁrst noted by de Oliveira-Costa et al.[4],the directions preferred by the quadrupole and the octopole point roughly towards the Virgo cluster—which is in the general vicinity of the dipole and the equinox,and has been dubbed the“axis of evil”[9].These large-scale anisotropies appear when one compares the northern/western galactic hemisphere(where Virgo and most of the Local Supercluster lie)with the southern/eastern hemisphere[3]as well. Unusually high correlations with the ecliptic have also been reported[8].In this paper we investigate whether these large-scale anomalies can be due to extended(large-angle)foregrounds that have so far escaped detection.In particular,we re-examine a speculation by Abramo&Sodr´e[25]that the explanation for the observed properties of the quadrupole and octopole is a diﬀuse,large-angle CMB foreground spatially correlated with the region of the sky occupied by the local supercluster(LSC)–which is a spot roughly 50o×30o centered around Virgo,at(l,b)=(284o,74o).The peak temperature of this foreground would have to be of order∼20µK,with a root-mean-square average temperature of order∼8µK.Such a foreground would have the correct geometry to aﬀect the quadrupole and octopole in a positive way,erasing their alignments and signiﬁcantly increasing the amplitude of the quadrupole.One of the physical processes that could produce such a foreground is the thermal Sunyaev-Zeldovich eﬀect(SZe)due to hot electrons in the intra-supercluster(ISC)medium[25].For the range of frequencies observed by WMAP and COBE,the ISC gas causes an apparent decrease in the temperature of the CMB photons in the direction of the LSC.We have estimated,using a simpliﬁed model,that a temperature distortion as high as|∆ˆTℓ=2|rms≈8µK is marginally consistent with present constraints on the ISC medium and with spectral distortions of the CMB.The possibility that foregrounds could be responsible for the alignments was also noted in[26],and two recently related explanations were proposed by Rakic,Rasanen and Schwarz[27]and by Inoue and Silk[28].Rakic et al. studied the Rees-Sciama eﬀect due to a nearby large-scale structure(or structures),and found that the ensuing foreground could be as high as∼30µK,but that the phases were not right to eliminate the alignments and the low quadrupole.Inoue and Silk,on the other hand,speculate that the non-gaussian cold spot in the southern galactic hemisphere [29]could be caused by voids in the nearby large-scale structure[28].They conclude that the contribution from compensated pairs of voids would have the right phases to account for the low amplitude of the quadrupole and the for the unusual quadrupole-octopole alignment.Notice that,because the quadrupole is even under parity transformationsˆn→−ˆn,any given pattern has the same quadrupole components as its specular image.Since the eﬀect discussed here relies mostly on a distortion of the quadrupole(which is both low-amplitude and has fewer phases than the octopole),this partly explains the apparent equivalence between the foreground proposed by Abramo&Sodr´e and foregrounds located in the southern galactic hemisphere,such as those proposed by Inoue&Silk.Furthermore,because most of the power of the observed CMB quadrupole lies in its m=0and m=±2components,another probable spot for an extended foreground corresponds to the location of Virgo,rotated180o around the galactic poles axis–that is,(l,b)≈(100o,70o).By placing one of these hypothetical foregrounds(henceforth HFg)on random locations,removing it from a CMB map and then computing the likelihood of the“cleaned”map,we have been able to test the randomness of the spatial correlation with the four dual points described above.Weﬁnd that,in all maps and in all foreground models tested, the most probable places for them are indeed either the vicinities ofˆn LSC,−ˆn LSC or near the ecliptic poles.We will show that,of all possible locations for this HFg,the LSC and its dual points produce the most signiﬁcant improvements in the likelihoods of the CMB maps,by both increasing the(too low)level of the quadrupole C2and by weakening the(too high)quadrupole-octopole alignment.This can be achieved with HFg’s whose rms temperatureslie in the range5−15µK and quadrupoles C F grd2∼50−120µK2,depending on the model.We have analysed the WMAP(1-year and3-year)Internal Linear Combination maps[1,2](henceforth ILC),the map of Tegmark et al.[10,21](henceforth TOH),as well as the co-added maps based on1-year and3-year WMAP data(henceforth Coadded)For the ILC and Coadded maps we use the Kp2maks,and for the TOH map we use the masks M0and M6described in[21].In all cases the low value of the quadrupole and the alignments are robust,and removal of the HFg leads to dramatic increases in the likelihoods of the CMB maps.This strongly argues in favour of still unknown diﬀuse,large-angle structures around the dipole axis that may be aﬀecting the CMB.This paper is organized as follows:In Sec.II we summarize the multipole vector formalism and the statistics of alignments for CMB maps.In Sec.III we present a model of the HFg based on the LSC,and argue that it may be due to the Sunyaev-Zeldovich eﬀect caused by hot gas in the intra-supercluster medium.In Sec.IV we consider thespatial location of the foreground,and show that the association with the dipole axis is not an accident.We conclude in Sec.V.II.LOW QUADRUPOLE AND ALIGNMENTSKatz and Weeks[20]have described,in a beautiful paper,how to compute all multipole vectors given the spherical harmonic components aℓm–see also[23].The multipole vectors,introduced to CMB data analysis by Copi et al.[7],are essentially eigenvectors of a simple set of algebraic equation whose parameters are the multipole components. Very similar computations were conducted using other(usually numeric)methods in[3,4,8]toﬁnd these vectors. The idea,which goes back to J.C.Maxwell in the XIX th century,is that the multipole decomposition of aﬁeld on S2implies that for each momentℓthere areℓeigenvectors of norm unity,ˆn(ℓ,p).The bottom line of the multipole vector analysis is that the expansion in spherical harmonics is equivalent to an expansion in multipole vectors:∆Tℓ(θ,ϕ)| w(2,1)· w(3,1)|+| w(2,1)· w(3,2)|+| w(2,1)· w(3,3)|,(2)3and the D statistic,which is analogous to S but disregards the norm of the normal vectors:1D≡FIG.1:Normalized P.D.F.’s for the S statistic(left panel)and D statistic(right panel),found by simulating3×105mock maps,binned in intervals of0.01.CMB Map P−(C2)P+(S)201.20.797 1.6×10−3TOH Mask0-LSC 1.02×10−1 1.99×10−1242.00.776 4.1×10−3TOH Mask6-LSC 1.38×10−1 2.19×10−197.70.748 1.2×10−3Coadded(1yr)-LSC 4.25×10−2 2.85×10−1100.50.746 1.3×10−3Coadded(3yr)-LSC 2.52×10−2 1.17×10−1139.70.727 4.1×10−3ILC(1yr)-LSC 6.77×10−2 2.19×10−1111.70.720 3.0×10−3ILC(3yr)-LSC 3.68×10−2 2.19×10−1TABLE I:Quadrupoles and alignments of CMB maps with and without the hypothetical LSC foreground subtracted.Shown are the Coadded and ILC maps with the3-year KP2mask[1,2],and the TOH map with and without the mask described in [10](based onﬁrst year WMAP data).P−(C2)is the probability that a random map has quadrupole as low as C2,and P+(S) is the probability that a random map has a quadrupole-octopole alignment as high as S.Also shown(last column)is the unbiased joint probability P Tot=16×P−(C2)×P+(C2)×P−(S)×P+(S),which estimates the likelihood that a random map has an anomalous(too high or too low)quadrupole and an anomalous(too high or too low)quadrupole-octopole alignment. In all cases,removal of the foreground leads to an improvement of about two orders of magnitude in P Tot.being the Coadded,ILC,LILC,TOH and the Q-,V-and W-band frequency maps.For all except the TOH map (which is already cleaned)we have use the KP2mask based on three-year WMAP data[1].It must be noted that the relativistic Doppler correction to the quadrupole is an important factor that must be subtracted from the maps,since it corresponds to a non-primary source of the quadrupole[8].In Table I we present the quadrupoles and their alignments with the octopoles,for a few CMB maps.The Coadded and ILC maps use3-year WMAP data,while the TOH map uses theﬁrst-year WMAP data only.The alignments are robust in all maps,as has been noted by[8,9,10].In the next section we will construct a model foreground based on the LSC,and Table I presents the statistical eﬀect of the subtraction of this LSC-shaped foreground.Notice that the relative error for the probabilities can be estimated as∆P(X)/P(X)∼1/FIG.2:Projected volume of the LSC on a Mollweide projection–the left edge corresponding to l=0o,the middle meridian to l=180o and the horizontal line to b=0o in galactic coordinates.Virgo is at the center of the LSC,at(l,b)≈(284o,74o).channels observed by COBE and WMAP,this eﬀect would cause a cold spot with the shape and location of the supercluster superimposed on the primary CMB data.We will show next that there are strong indications that an LSC-related foreground(or some structure diametrically opposite to the LSC)is distorting the observed CMB sky.Whether or not that foreground is caused by the SZe[25],a void[28],some other mechanism such as the Rees-Sciama(or Integrated Sachs-Wolfe)eﬀect[27],or even a combination of those,remains to be seen.A.Shape and location of the Local SuperclusterThe morphology of the LSC is relatively well known[31]:it is aﬂattened collection of groups and clouds of galaxies centered at the Virgo Cluster,which contains∼20%of its bright galaxies.The Local Group is dynamically linked to the LSC,and lies∼15Mpc from Virgo,at the border of the LSC.Notice that the LSC itself is not a virialized structure,hence the gas in its midst is not necessarily in equilibrium.Since we are interested in an analytic approach at this point,a radical simpliﬁcation will be made,approximating the shape of the LSC by an oblate spheroid of maximal radius20Mpc with approximate axial ratios6:2:1[31]. Therefore,our simple model assumes that the LSC is a collection of objects(clouds,groups and the Virgo cluster) which are distributed smoothly across the spheroid.The Sun stands at the margin of the spheroid(which looks like aﬂattened rugby ball),approximately15Mpc away from Virgo.In our foreground model we assume that the intensity of the temperature decrement is proportional to the volume of the LSC,projected along the line of sight(i.e.,the surface density.)This must be roughly correct,whatever the source of the hypothetical foreground,if it is indeed correlated with a diﬀuse structure such as the LSC.It is trivial to compute the surface density,given the shape and orientation of the LSC,and the result of this projection can be seen in Fig.2for an arbitrary(but constant)density.In thatﬁgure it can also be seen that our LSC model’s projection on our sky is a spot of roughly50o×30o.The oblate spheroid,in a conveniently rotated frame,is deﬁned by the surface:(bx′)2+(cy′)2+z′2=A2,(4) where A is the major axis(along the direction z′),and b and c are the ratios of the minor axes to the major axis. The LSC parameters are A≈20Mpc,b≈3and c≈6.With these values the semi-major axes are B=A/b≈6.7 Mpc and C=A/c≈3.3Mpc.Assuming that the Sun is located at a distance R under the z′-axis of the spheroid, the distance to the surface of the spheroid along lines-of-sight emanating from the Sun are given by:1r S(θ′,φ′)=R2cos2θ′+(A2−R2) 1+sin2θ′ (b2−1)cos2ϕ′+(c2−1)sin2ϕ′ .FIG.3:Angular power spectra of the LSC foreground model(left panel),where we useα=1–see Eq.(11);and of the Disk (uniform-temperature)foreground model,with angular diameters of30o(diamonds),50o(stars)and70o(squares.) Obviously,if the density is uniform inside the spheroid then the surface density will be proportional to r S.We can use the surface density of the LSC as the blueprint for a foreground,and therefore consider the temperature decrement caused by the foreground to be proportional to r S.In Fig.3(left panel)we show the spectrum of anisotropies for such a model,where the proportionality constant is set by assuming that the eﬀect is caused by scattering of the CMB photons by hot electrons in the ISC medium–see below.Notice that the quadrupole is substantially higher than the other multipoles,because the foreground’s temperature is not constant as the line of sight moves away from the center of the LSC.This sorts out the quadrupole as the biggest contribution to the power spectrum,and in fact the RMS temperatureﬂuctuation over the whole sky is well approximated by the quadrupole. Given our ignorance about the existence,shape and form of this hypothetical foreground,we could equally well assume,following Inoue&Silk[28],that the temperature of the foreground is approximately uniform,falling quickly to zero away from the center of the spot.In Fig.3(right panel)we show the anisotropy spectra of three such spots–with angular diameters of30o,50o and70o.The fact that the temperature is uniform inside the spot means that the low multipoles contribute more evenly to the foreground.Hence,for a given RMS temperatureﬂuctuation there is less power in the quadrupole in the uniform-temperature foreground relative to the varying-temperature foreground. Moreover,as higher multipoles are more important in the uniform-temperature foreground,if that is the case then it may be possible toﬁnd independent corroborating evidence by searching for anomalous alignments in the higher multipoles(e.g.,ℓ=4andℓ=5)as well.This will be analysed in Sec.IV.B.Foreground model:Sunyaev-Zeldovich eﬀect in the LSCThe SZe is caused by the inverse Compton scattering of CMB photons by hot electrons in the intra-cluster medium [32].It is a nonthermal,frequency-dependent eﬀect:the upscattering causes an incident blackbody spectrum of photons to become distorted in such a way that the resulting higher abundance of high-energy photons is compensated by a shortage of low-energy photons.The spectral distortion is given by[32]:∆T(θ,ϕ;ν)−4 ,(6)2where T0=2.726K is the temperature of the CMB,y is the comptonization parameter in the directionˆn(θ,ϕ)and x=hν/k B T0.The frequency at which photons are neither depleted nor overproduced isν0=218GHz[33]—COBE/DMR and WMAP work in the range20-90GHz.For frequencies belowν0the eﬀect is a nearly uniform reduction in the temperature of the photons,∆T/T≈−2y,and for frequencies above that the eﬀect is the opposite.This means that measurements over a range of frequencies aroundν0(such as PLANCK’s LFI and HFI[53])can pick up the signal of the SZe and distinguish it from the primary anisotropies.The comptonization parameter y measures an optical depth for the CMB photons created by the hot electrons,and its value is given by the product of the Thomson cross-sectionσT=6.65×10−25cm2times the temperature-averageddensity of photons along the line of sight[33]:y= σT kT e,(8)µe m pwhere M LSC is the LSC mass,f g is the gas fraction,µe is the molecular weight per electron and m p is the proton mass.We may assume that the mass of the LSC is∼7×1015M⊙[49].Assuming that the Hydrogen is fully ionized and that the helium mass fraction is Y=0.24,thenµe=1/(1−Y/2)≃1.14.The gas fraction is not very well known,but X-ray observations of clusters indicate that f g≈0.06h−3/2[52].The fraction could be diﬀerent in the ISC medium,but we will assume for simplicity that the fraction in clusters is the same as ing h=0.7we getﬁnally that the total number of electrons in the LSC should be of order N e∼7×1071.A very simple model for the LSC gas is to neglect the gas phases and the substructures inside the supercluster, and to assume that the gas is uniformly distributed inside the LSC.Hence the total volume occupied by the gas is V LSC=4π/3×ABC and therefore the average density of electrons in the LSC is approximately:N en e=of the electron density,if the gas temperature is indeed2keV,then the upper bound for the electronic density is of order n e≈5×10−5cm−3.This corresponds to a collapse factor of only a few.We can estimate the comptonization parameter assuming a constant electron density across the LSC.If the gas has an average temperature of2keV then kT e /m e c2≃0.004,and with a maximum line-of-sight distance(in the direction of Virgo)of∼30Mpc we obtain that the comptonization parameter is at most:∆y≈σT kT e5.10−5cm−3×10−5.(10)The comptonization parameter can be exactly computed from Eq.(7)for our oblate spheroid model,if we assume that the density and temperature of the hot gas is uniform inside the LSC,and zero outside it.In that case the comptonization parameter is proportional to the projected distance to the surface of the spheroid,Eq.(5).The resulting angular power spectrum for the SZe of the LSC in this model is given in Fig.3.The amplitude of the SZe quadrupole is:∆ˆT22≡65×10−5cm−3×kT eFIG.4:Locations of the HFg-LSC model applied to the“mask0”TOH map[10,21].The largest,darkest spot marks the top foreground as measured by the highest values of P T ot obtained after3000random rotations of the putative foreground.The top5%,10%,15%and33%foregrounds are indicated by the progressively smaller and lighter spots.The smallest,lightest spots mark the bottom67%locations.Here and in Figs.6-16,instead of the Mollweide projection,we use a simple map (θ,ϕ)→(θ,ϕsinθ).FIG.5:Same as before,in the case of the HFG-D model applied to the“mask0”TOH map[10,21].angle dependence coincides roughly with the angular dependence of the quadrupole.Therefore,the amplitude of the temperature distortion in the HFg-D model must be higher than in the HFg-LSC model in order to get the same level of the quadrupole.So,whereas in the HFg-LSC model the peak temperature distortion is of order−90µK,with a quadrupole C2≈60µK2,for the HFg-D model to get the same quadrupole the temperature of the50o×50o spot must be T Disk≈−130µK.For each model we rotate the putative foreground by random Euler angles and subtract it from a CMB map to obtain the“cleaned”map.We then look for the corrected maps with highest likelihoods,as measured by the largest value of the unbiased probability P T ot.We used2000random rotations for each foreground model and for each map of Table I(all with the KP2mask applied.)The results are shown in Figs.5-16,where each spot marks the location of a hypothetical foreground.The dark spots mark the locations of the top5%of foregrounds as measured by the likelihood of the cleaned maps.The lighter, smaller spots mark the location of the top10%,20%and so forth.The bottom50%locations are shown as the smallest,lightest spots.The top foreground in each case is shown in Table II,along with its location and likelihood. It can be seen from Figs.5-16that,in most cases,there is a strong clustering of the preferred locations around Virgo(and the LSC),its diametrically opposite point,and the region which correspons to Virgo rotated180o around the z-axis.The preferred locations seem to be more scattered for the3-year Coadded map with both foreground models,and for the ILC maps with the HFg-LSC model.There is a simple explanation for the spatial distribution seen throughout Figs.5-16:the HFg’s change P T ot mostly by amplifying and rotating the quadrupole of the original maps.But the quadrupole is even under parity transformationsˆn→−ˆn,therefore from the point of view of the quadrupole,it is irrelevant if the foreground is at the LSC or at its diametrically opposite side.Moreover,since most of the power of the quadrupole lies in itsℓ=2,m=0 andℓ=2,m=±2components,a rotation by180o degrees eﬀects very little change to it.Therefore,if the foreground which is distorting the CMB is indeed at the LSC,then its preferred locations in a blind search will degenerate toFIG.6:Same as before,in the case of the HFg-LSC model applied to the“mask6”TOH map[10,21].FIG.7:Same as before,in the case of the HFg-D model applied to the“mask6”TOH map[10,21].not only the vicinity of the LSC itself,at(l,b)=(284o,74o),but also to its“dual points”at(l,b)≈(104o,−74o)and (l,b)≈(104o,74o).This is indeed what seems to happen for most maps–see Table2.It is interesting to notice that,even though the amplitude of the octopole of the HFg-LSC model is subdominant, in the HFg-D model there is a substantial change in the octupole after the subtraction.Although the impact of the octopole in P T ot is small,there are other statistical tests which are sensitive to it–in particular,the S(4,4)statistic of Copi et al.[7,8]which tests for an alignment of the quadrupole and octopole with the ecliptic plane.The3-year Coadded and ILC maps have too high values of S(4,4)at99.5%C.L.After subtracting the best-ﬁt Disk foreground model,those values come down to84%C.L.for the Coadded map and to98%C.L.for the ILC map.FIG.8:Same as before,in the case of the HFg-LSC model applied to the1-year Coadded map.FIG.9:Same as before,in the case of the HFg-D model applied to the1-year Coadded map.FIG.10:Same as before,in the case of the HFg-LSC model applied to the3-year Coadded map.A.Higher multipolesIf the HFg indeed exists,it may be possible to detect correlations in the higherℓcomponents as well.However, depending on the model,the spectrum of the foreground can decay with largeℓ,and the increasing number of phases means that these correlations will probably diﬃcult to detect.If the foreground is homogeneous(as in the Disk model),the higher multipoles can also become important and their presence may aﬀect the alignments between,say,ℓ=2−5.It is trivial to generalize the tests of Eqs.(2)-(3)for higher multipoles–see,e.g.,[20,24].If a given foreground cures the quadrupole level and the quadrupole-octopole alignment at the cost of introducing anomalous alignments between other multipoles,then the overall likelihood of the resulting map should fall.On the other hand,if theFIG.11:Same as before,in the case of the HFg-D model applied to the3-year Coadded map.FIG.12:Same as before,in the case of the HFg-LSC model applied to the1-year ILC map.FIG.13:Same as before,in the case of the HFg-D model applied to the1-year ILC map.original CMB map has another anomalous alignment which is relaxed because of the hypothetical foreground,then the likelihood of the resulting map increases even further.We have tested the maps of Table II for signs of anomalous alignments between the higher multipoles using an unbiased probability with38tests,P38–which includes the level of the quadrupole and the quadrupole-octopole align-ment[24].The results are mixed,and probably reveal intrinsic diﬀerences between the maps,masks and foreground models.For example,whereas the original TOH map with the Mask6[10,21]has P38=3.5×10−15,subtraction of the best-ﬁt HFg-LSC model leads to an improvement to P38=3,5×10−10,while subtraction of the best-ﬁt HFg-D model improves it to P38=2,4×10−7.For the Coadded map(3-year data)with the KP2mask[1,2],the original map has P38=4.4×10−13,and after subtracting the best-ﬁt HFg-LSC model it only improves to P38=1,1×10−9, while subtraction of the best-ﬁt HFg-D model leads to P38=3,7×10−8.Notice that in all cases above,the level ofFIG.14:Same as before,in the case of the HFg-LSC model applied to the3-year ILC map.。