VLA H53alpha observations of the central region of the Super Star Cluster Galaxy NGC 5253

合集下载

Observations of volcanic ash by lidar and MODIS

Calculations for different possible refractive indices: median diameter greater than 800
microns
Upper bound ~2 microns assuming not liquid water
Colour ratios
it did over Chilbolton…
As over Chilbolton, ash much more depolarizing than ordinary
boundary-layer aerosol
Calipso lidar 16th April
Ash higher at leading (southern) edge, explaining the descending appearance to groundbased lidar
• The amounts are much less that UK air quality objective (1 hr average exceeds 350 mg m-3 less than 24 times per year)
No convincing sign of ash
Aerosol particles (PM10s)
microns
Colour ratios: 905/1500
Note contrast with ordinary boundary layer different possible refractive indices: median diameter greater than 800
Ultraviolet EZ-lidar, Cardington Bedfordshire, 16th April

On the Purity of the ZZ Ceti Instability Strip Discovery of More Pulsating DA White Dwarfs

a r X i v :a s t r o -p h /0309483v 1 17 S e p 2003On the Purity of the ZZ Ceti Instability Strip:Discovery of More Pulsating DA White Dwarfs on the Basis of Optical Spectroscopy 1P.Bergeron and G.FontaineD´e partement de Physique,Universit´e de Montr´e al,C.P.6128,Succ.Centre-Ville,Montr´e al,Qu´e bec,Canada,H3C 3J7.bergeron@astro.umontreal.ca,fontaine@astro.umontreal.caM.Bill`e resEuropean Southern Observatory,Santiago Headquarters,Avenida Alonso de Cordova 3107,Vitacura,Casilla 19001,Santiago 19,Chile.mbilleres@S.BoudreaultD´e partement de Physique,Universit´e de Montr´e al,C.P.6128,Succ.Centre-Ville,Montr´e al,Qu´e bec,Canada,H3C 3J7.boudreault@astro.umontreal.caandE.M.GreenSteward Observatory,University of Arizona,Tucson,AZ 85721.egreen@ABSTRACTWe report the discovery of two new ZZ Ceti pulsators,LP 133−144and HE1258+0123,selected on the basis of model atmosphere ﬁts to optical spectroscopic data.The atmospheric parameters for LP 133−144,T eﬀ=11,800±200K and log g =7.87±0.05,and for HE 1258+0123,T eﬀ=11,410±200K and log g =8.04±0.05,place them within the empirical boundaries of the ZZ Ceti instability strip.This brings the number of known ZZ Ceti stars to a total of 36,a quarter of which have now been discovered using the spectroscopic approach for estimating their atmospheric parameters.This method has had a 100%successrate so far in predicting the variability of candidate ZZ Ceti stars.We have alsoanalyzed additional spectra of known nonvariable white dwarfs in the vicinity ofthe ZZ Ceti instability strip.Our study further strengthens the idea that ZZ Cetistars occupy a pure region in the log g−T eﬀplane,a region where no nonvariablestars are found.This result supports the thesis that ZZ Ceti pulsators representa phase through which all DA stars must evolve.Subject headings:stars:fundamental parameters—stars:individual(LP133−144,HE1258+0123)—stars:oscillations—white dwarfs1.IntroductionPulsating hydrogen line(DA)white dwarfs—or ZZ Ceti stars—are found in a rather narrow range of eﬀective temperature,between about T eﬀ=12,500K and11,100K according to the detailed study of Bergeron et al.(1995,hereafter B95),with the temperatures deﬁning the blue and red edges depending on the mass of the white dwarf.Asteroseismological studies of these stars provide important constraints on their internal structure,including their chemical layering.If ZZ Ceti stars truly represent an evolutionary phase through which all DA white dwarfs must go through,then the results obtained for the pulsators can be generalized to the entire class of DA stars as well.In particular,the asteroseismological determinations of the hydrogen and helium envelope masses in DA white dwarfs can be used as“calibration”of these quantities in cooling calculations.Hence it is important to determine the fraction of white dwarfs inside the ZZ Ceti instability strip that are nonvariable.More than twenty years ago,Fontaine et al.(1982)have argued from a study of multichannel photometric data that the strip is most likely pure.This question of the purity of the ZZ Ceti instability strip has been debated in the meantime by various authors(e.g.,Dolez et al. 1991;Kepler&Nelan1993;Kepler et al.1995;Silvotti et al.1997;Giovannini et al.1998) who claimed,contrary to Fontaine et al.(1982),that the strip contains both variable and nonvariable stars.A deﬁnite answer to this question had to wait for a more precise method of measuring the atmospheric parameters of ZZ Ceti stars and other white dwarfs in the vicinity of the instability strip.B95have developed such a theoretical framework for measuring the eﬀective temperature and surface gravity of ZZ Ceti stars by comparing high signal-to-noise ratio(S/N>∼80)spectroscopic observations with the predictions of model atmospheres.The method uses simultaneousﬁts to the Balmer lines,from Hβto H9.This so-called spectroscopic technique hasﬁrst been applied to hotter white dwarfs by Bergeron et al.(1992)to determine the mass distribution of DA stars,and it is arguably the most precise method for measuring the atmospheric parameters of white dwarf stars.Although the approach used by B95has been the subject of various criticisms,Fontaine et al.(2003)have reviewed and rebutted all the arguments that have been put forward against the use of optical spectroscopy.In particular,Fontaine et al.(2003)have demonstrated the usefulness of the spectroscopic technique to obtain accurate measurements of the atmospheric parameters of ZZ Ceti stars as well as neighboring stars in the log g−T eﬀdiagram,and to predict the variability of ZZ Ceti candidates.Fontaine et al.have also shown that the atmospheric parameters for all 34known ZZ Ceti stars and103nonvariable stars obtained with the optical spectroscopy approach deﬁne a very narrow region in the log g−T eﬀplane in which no nonvariable stars are found(see Fig.3of Fontaine et al.2003),in agreement with our thesis that ZZ Ceti stars represent a phase through which all DA white dwarfs must evolve.With this powerful diagnostic tool in hand,it becomes possible to identify ZZ Ceti candidates from large white dwarf samples by securing spectroscopic observations for all objects,and by determining T eﬀand log g values from model atmosphereﬁts to optical spectroscopy.To obtain reliable and consistent results,however,three conditions must be met:(1)High-quality spectra must be gathered,(2)model atmospheres comparable to those of B95(and based on the calibration of the mixing-length theory proposed there)must be used,and(3)attention to details must be provided(see B95and references therein). Stars with atmospheric parameters overlapping the currently known ZZ Ceti stars ought to be variable according to our past results.There are currently34known ZZ Ceti stars,7of which have been discovered using the spectroscopic technique:GD165(Bergeron&McGraw 1990),HS0507+0435B(Jordan et al.1998),PG1541+650(Vauclair et al.2000),GD244 and KUV02464+3239(Fontaine et al.2001),and more recently MCT0145−2211and HE 0532−5605(Fontaine et al.2003).In this paper we present spectroscopicﬁts that led to the discovery of two more pulsators,LP133−144and HE1258+0123,for a total of36ZZ Ceti stars known up to date.We also present an upgraded view of the ZZ Ceti instability strip in the log g−T eﬀdiagram.2.LP133−144Liebert et al.(2003)have recently obtained high S/N spectroscopy of all DA white dwarfs identiﬁed in the Palomar-Green(PG)survey(Green et al.1986).One of the goalsof that eﬀort is to derive an improved luminosity function using the spectroscopic approach. Among the347DA stars analyzed in that way,9objects were previously known to be ZZ Ceti variables(GD99,G117−B15A,GD154,G238−53,GD165,PG1541+651,R808,PG 2303+243,and G29−38).Among the remaining PG stars,only one object,LP133−144(PG 1349+552,WD1349+552,B ph≃16.0),has atmospheric parameters(T eﬀ=11,800K and log g=7.87)consistent with it being a ZZ Ceti pulsator.Our bestﬁt using ML2/α=0.6 models(see B95)is shown in Figure1.Because Balmer lines in the ZZ Ceti range are,in fact,very sensitive to both T eﬀand log g,internal errors obtained from least-squaresﬁts to high S/N optical spectra are meaningless,as discussed in detail by Bergeron et al.(1992)and B95.The typical goodﬁts that are achieved only reﬂect the ability of the model spectra to match the data,and the error budget is actually dominated by uncertainties of theﬂux calibration.To estimate the true external errors,Fontaine et al.(2003)have compared the atmospheric parameters of a subset of ZZ Ceti stars taken from B95with those derived from independent spectra obtained by Chris Moran(2000,private communication),using a completely diﬀerent setup and reduction procedure(see also Bergeron et al.1992,for a similar comparison at higher temperatures). As can be seen from Figure2of Fontaine et al.(2003),the standard deviations between both sets of measurements allow us to estimate the real external errors for stars in the ZZ Ceti range,σ(T eﬀ)∼200K andσ(log g)∼0.05.Since all the stars in this paper are found in the same temperature range(see Fig.1of Fontaine et al.2003)and have been observed with the same setup and signal-to-noise ratio,we adopt these uncertainties throughout.To our knowledge,LP133−144had never been observed before for photometric vari-ability,most likely because there is no published color information on this white dwarf(see Fontaine et al.2001for a historical account of the selection criteria used previously for uncovering ZZ Ceti stars).As part of an ongoing program to identify new ZZ Ceti pulsators, we observed LP133−144in integrated(white light)“fast”photometric mode at the Steward Observatory Mount Bigelow Station1.6m telescope during four nights in March-April2003. The photometric observations were obtained with LAPOUNE,the portable Montr´e al three-channel photometer.A total of17.6h of data was gathered.The top two panels of Figure 2show our sky-subtracted,extinction-corrected light curves obtained during the discovery run.Clearly,LP133−144is a multiperiodic luminosity variable,a new ZZ Ceti star.The top panel of Figure3shows the resulting Fourier(amplitude)spectrum of the light curve of LP133−144using all the17.6h of data.From this spectrum,we can easily identify four main frequency components corresponding to periods in the range from209.2to327.3 s.We note that the relatively short periods and low amplitudes(<∼1%)of the luminosity variations detected in LP133−144are consistent with its location near the blue edge of theZZ Ceti instability strip(see§4).3.HE1258+0123The two ZZ Ceti stars MCT0145−2211and HE0532−5605recently discovered by Fontaine et al.(2003)have published T eﬀand log g values taken from Koester et al.(2001) as part of the SPY program.These two ZZ Ceti candidates have been selected by Fontaine et al.because they happen to fall precisely in the middle of the empirical ZZ Ceti instability strip determined by B95.Two other SPY objects shown in Figure3of Fontaine et al.(2003), EC12043−1337(WD1204−136,V=15.52)and HE1258+0123(WD1258+013,V=16.26), fall also inside the instability strip,but very close to the cool edge of the strip.During our March-April2003observing run when the variability of LP133−144was discovered,we also obtained high speed photometric data on EC12043−1337,which showed a constant light curve at the2−3millimag level.We had also secured similar observations on HE1258+0123, but we later discovered that we had observed the wrong star,since the coordinates provided in Koester et al.(2001)for this object,α(2000)=13:00:59.2andδ(2000)=+00:57:12, correspond to the sdO star HE1258+0113according to Christlieb et al.(2001),who gives instead for HE1258+0123α(2000)=13:01:10.5andδ(2000)=+01:07:39.In June2003,we secured our own spectroscopic observations for both EC12043−1337 and HE1258+0123using the2.3m telescope at the Steward Observatory Kitt Peak Station, equipped with the Boller&Chivens spectrograph and a Texas Instrument CCD detector. The spectral coverage is aboutλλ3100–5300,thus covering Hβup to H9at an intermediate resolution of∼6˚A FWHM.Our bestﬁt for EC12043−1337using our own model grid is shown in Figure1.The atmospheric parameters for this object,T eﬀ=11,200K and log g=8.23,now place it close to,but below,the empirical red edge of the instability strip,in agreement with our high speed photometric result.Koester et al.(2001)obtained T eﬀ=11,111K and log g=8.05for the same star.Our spectroscopic solution for HE1258+0123,T eﬀ=11,410K and log g=8.04,is shown in Figure1,which can be compared with the results of Koester et al.(2001)for the same star,T eﬀ=11,161K and log g=7.92.These revised parameters push HE1258+0123 even deeper within the empirical instability strip.On the basis of our previous success at predicting the variability of ZZ Ceti candidates using the optical spectroscopy approach,we ﬁgured that this star ought to be variable.One week later,one of us(M.B.)managed to obtain high speed photometric observations of HE1258+0123using the EMMI instrument attached to the3.6m New Technology Telescope(NTT)at the ESO La Silla Station.The exposure time was adjusted from20s to15s as the seeing improved,with correspondingsampling times of55s and49s,respectively.Images were bias subtracted,ﬂatﬁelded, and magnitudes were calculated using the mag/circ function of the MIDAS package.The 3.3hour long photometric light curve is shown in the lower panel of Figure2.The results conﬁrm our expectation that HE1258+0123is indeed a multiperiodic luminosity variable, another ZZ Ceti star.The Fourier spectrum for this single run is displayed in the lower panel of Figure3.The dominant peak at744.6s is consistent with this ZZ Ceti star being closer to the red edge of the instability strip than LP133−144(see§4).Other important peaks are also present at439.2,528.5,and1091.1s.The sharp rises and slow declines observed in the light curve are characteristic of large amplitude ZZ Ceti stars.4.The Empirical ZZ Ceti instability stripOf the four SPY objects originally found inside the empirical instability strip(see Figure 3of Fontaine et al.2003),three remain within the strip according to our own spectroscopic analysis,and they correspond indeed to new ZZ Ceti stars(MCT0145−2211,HE0532−5605, and HE1258+0123).For its part,the nonvariable white dwarf EC12043−1337has a revised eﬀective temperature and a surface gravity that put it slightly below the empirical red edge of the strip.Two additional objects lie formally within,but very close to the blue edge of the instability strip shown in Figure3of Fontaine et al.(2003).The one at the top is LP550−52with T eﬀ=11,550K and log g=7.65,an unresolved degenerate binary with a period of1.157days according to Maxted et al.(1999).The atmospheric parameters for this object are thus an average of the parameters of both components of the system(Liebert et al.1991),and we will no longer consider it in our analysis.The other object seen in Figure3of Fontaine et al.(2003)is GD133at T eﬀ=12,090K and log g=8.06.Given the uncertainties,the position of that object inside the strip,but very close to the blue edge,certainly remains consistent with the idea of a pure strip.Nevertheless,given that the spectrum we used for GD133had not been obtained by us,we reobserved it in June 2003with our standard setup.Our revised atmospheric parameters,T eﬀ=12,290K and log g=8.04,now place GD133above the blue edge of the ZZ Ceti instability strip.Our updated empirical ZZ Ceti instability strip is shown in Figure4where the positions of all known variables are indicated,together with the results for54known nonvariable white dwarfs.For the convenience of the reader,we provide in Table1a summary of the atmospheric parameters for all36known ZZ Ceti stars.The table assembles values taken from B95(22stars),Fontaine et al.(2003,12stars),and this paper(2stars).The values of T eﬀand log g are determined from ML2/α=0.6models,while the stellar masses are derived from the models of Wood(1995)for carbon-core compositions,helium layers ofM He=10−2M⋆,and hydrogen layers of M H=10−4M⋆.Note that some very small changes appear with respect to some of the B95data,the result of redoing theﬁts in a completely homogeneous way.The picture of the empirical instability strip that emerges from our results is that of a pure strip in which no nonvariable stars are found,a conclusion that supports our claim that ZZ Ceti stars represent a phase through which all DA stars must evolve.It has a trapezoidal shape in the log g−T eﬀplane,with the blue edge showing a stronger dependence on the surface gravity than the red edge does,although this conclusion rests heavily on the most massive ZZ Ceti star in this diagram,LTT4816(WD1236−495). The newly discovered ZZ Ceti stars reported in this paper are shown as bold open circles in Figure4,and their location within the instability strip together with their dominant periods found from the Fourier spectra(Fig.3)are consistent with the period-eﬀective temperature relation observed in ZZ Ceti pulsators(see,e.g.,Winget&Fontaine1982).In Figure4there appears to be a paucity of stars directly above the blue edge and below the red edge of the instability strip.However,our combined sample of variables and nonvariables is heavily biased against the latter since we have gathered spectra for only a fraction of them.Progress is underway to secure spectroscopic observations for all stars outside the boundaries of the instability strip,and to increase the number of nonvariable white dwarfs in the vicinity of the strip to help deﬁne better the exact location and shape of the red and blue edges.The spectroscopic approach,when properly handled,provides the most powerful way for discovering new ZZ Ceti stars in a routine fashion,and it could be easily applied to large surveys such as the Sloan Digitized Sky Survey.Interestingly enough,HE1258+0123 is also part of the Sloan survey(SDSS J130110.51+010739.9)and its variability should be rediscovered as part of that ongoing survey.We wish to thank the Director and staﬀof Steward Observatory for allowing us to use their facilities.This work was supported in part by the NSERC Canada and by the Fund NATEQ(Qu´e bec).G.F.also acknowledges the contribution of the Canada Research Chair Program.REFERENCESBergeron,P.,&McGraw,J.T.1990,ApJ,352,L45Bergeron,P.,Saﬀer,R.A.,&Liebert,J.1992,ApJ,394,228Bergeron,P.,Wesemael,F.,Lamontagne,R.,Fontaine,G.,Saﬀer,R.A.,&Allard,N.F.1995,ApJ,449,258(B95)Christlieb,N.,Wisotzki,L.,Reimers,D.,Homeir,D.,Koester,D.,&Heber,U.2001,A&A, 366,898Dolez,N.,Vauclair,G.,&Koester,D.1991,in White Dwarfs,ed.G.Vauclair&E.M.Sion (Kluwer:Dordrecht),361Fontaine,G.,Bergeron,P.,Bill`e res,M.,&Charpinet,S.2003,ApJ,591,1184 Fontaine,G.,Bergeron,P.,Brassard,P.,Bill`e res,M.,&Charpinet,S.2001,ApJ,557,792 Fontaine,G.,McGraw,J.T.,Dearborn,D.S.P.,Gustafson,J.,&Lacombe,P.1982,ApJ, 258,651Giovannini,O.,Kepler,S.O.,Kanaan,A.,Costa,A.F.M.,&Koester,D.1998,A&A,329, L13Green,R.F.,Schmidt,M.,&Liebert,J.1986,ApJS,61,305Jordan,S.,Koester,D.,Vauclair.G.,Dolez,N.,Heber,U.,Hagen,H.-J.,Reimers,D., Chevreton,M.,&Dreizler,S.1998,A&A,330,277Kepler,S.O.,&Nelan,E.P.1993,AJ,105,608Kepler,S.O.,Giovannini,O.,Kanaan,A.,Wood,M.A.,&Claver,C.F.1995,Baltic Astronomy,4,157Koester,D.,Napiwotzki,R.,Christlieb,N.,Drechsel,H.,Hagen,H.-J.,Heber,U.,Homeier,D.,Karl,C.,Leibundgut,B.,Moehler,S.,Nelemans,G.,Pauli,E.-M.,Reimers,D.,Renzini,A.,&Yungelson,L.2001,A&A,378,556Liebert,J.,Bergeron,P.,Holberg,J.B.,&Saﬀer,R.A.2003,in preparationLiebert,J.,Bergeron,P.,&Saﬀer,R.A.1991,in White Dwarfs,ed.G.Vauclair&E.M.Sion(Kluwer:Dordrecht),409Maxted,P.F.L.,&Marsh,T.R.1999,MNRAS,307,122Silvotti,R.,Bartolini,C.,Cosentino,G.,Guarnieri,A.,&Piccioni,A.1997in ASSL Conf.Ser.214,10th European Workshop on White Dwarfs,ed.J.Isern,M.Hernanz,&E.Garcia-Berro(Dordretch:Kluwer),489Vauclair,G.,Dolez,N.,Fu,J.N.,&Chevreton,M.1997,A&A,322,155Winget,D.E.,&Fontaine,G.1982,in Pulsations in Classical and Cataclysmic Variables, ed.J.P.Cox&C.J.Hansen(Boulder:Univ.of Colorado),142Wood,M.A.1995,in9th European Workshop on White Dwarfs,NATO ASI Series,ed.D.Koester&K.Werner(Berlin:Springer),41Table1.Atmospheric Parameters of ZZ Ceti stars WD Name T eﬀ(K)log g M/M⊙M VTable1—ContinuedWD Name T eﬀ(K)log g M/M⊙M V a This paperFig. 1.—Modelﬁts to the individual Balmer line proﬁles of the new ZZ Ceti stars LP 133−144and HE1258+0123,and of the nonvariable white dwarf EC12043−1337.The lines range from Hβ(bottom)to H9(top),each oﬀset vertically by a factor of0.2.Values of T eﬀand log g have been determined from ML2/α=0.6models,while the stellar masses have been derived from the models of Wood(1995)for carbon-core compositions,helium layers of M He=10−2M⋆,and hydrogen layers of M H=10−4M⋆.Fig.2.—Top two panels:Light curve of LP133−144,observed in“white light”with LA-POUNE attached to the Mount Bigelow1.6m telescope.Each point represents a sampling time of10s.Bottom panel:Light curve of HE1258+0123gathered using the EMMI instru-ment with noﬁlter attached to the NTT.Each plotted point represents a sampling time of approximately50s.Both light curves are expressed in terms of residual amplitude relative to the mean brightness of the star.Fig.3.—Fourier(amplitude)spectra of the light curves of LP133−144and HE1258+0123 in the0−10mHz bandpass.The spectra in the region from10mHz out to the Nyquist frequency are entirely consistent with noise and are not shown.The amplitude axis is expressed in terms of the percentage variations about the mean brightness of the star. Fig.4.—Surface gravity-eﬀective temperature distribution for various samples of DA white dwarfs.The open circles represent the36known ZZ Ceti stars tabulated in Table1;the bold open circles correspond to the newly identiﬁed ZZ Ceti stars LP133−144(left)and HE1258+0123(right).Filled circles are DA stars that are known to be nonvariable and whose atmospheric parameters have been determined by us on the basis of the same homo-geneous approach as the ZZ Ceti stars.The error bars correspond to the uncertainties of the spectroscopic method in the region where ZZ Ceti stars are located,σ(T eﬀ)∼200K andσ(log g)∼0.05,as estimated by Fontaine et al.(2003).The dashed lines represent the empirical blue and red edges of the instability strip.Figure4。

求解随机微分方程数值方法的稳定性与收敛性

1、对于 Itoˆ 型随机微分方程，主要研究了求解它的数值方法及方法的稳定性。首先通过对求解 Itoˆ 型随机微分方程的 Heun 方法进行改进得到 θ-Heun 方法。然后根据数值方法均方稳定和指数稳定的定义，证明了 θ-Heun 数值方法均方稳定和指数稳定的充要条件，以及均方稳定区域。接着给出了使 θ-Heun 数值方法均方稳定的 θ 的取值范围，并进行了数值验证。最后用数值实验对这两种数值方法的均方稳定性和渐进稳定性进行了对比。
1、For Itoˆ stochastic differential equations, The numerical method and its stability was studied mainly. First, θ-Heun method was obtained by improving the Heun method. Then, according to the definition of the mean square stability and exponential stability of numerical method, the mean square stability condition and the exponential stability condition of the θ-Heun method and its stability regions were gain. What’s more, the range of the θ that makes the stability of θ-Heun method was given, and the numerical validation was performed. Finally, the mean square stability and the asymptotic stability of these two methods were compared by numerical examples.

紫外法测定蛋白质含量校正公式原文

踏青去五阳湖作文的英文回答：On a sunny spring day, I embarked on a picturesque excursion to the serene shores of Wuyang Lake. The lake, renowned for its pristine waters and verdant surroundings, was a veritable oasis amidst the bustling city. As I strolled along the willow-lined path, I was enveloped in a symphony of vibrant colors and sweet fragrances. Birdsong filled the air, creating a harmonious chorus that echoed through the tranquil landscape.The lake's crystal-clear waters shimmered in the sunlight, reflecting the azure sky above. I could see fish darting beneath the surface, their scales glistening like tiny silver coins. The banks were adorned with lush vegetation, from wildflowers to towering trees, creating a vibrant tapestry of nature's beauty.As I ventured further into the park, I came across agroup of people engaged in various leisurely activities. Some were fishing from the pier, their lines cast into the calm waters. Others were picnicking on the grassy knolls, sharing laughter and good food. I observed childrenfrolicking in the playground, their laughter adding to the festive atmosphere.The highlight of my excursion was a leisurely boat ride on the lake. I boarded a small rowboat and paddled out into the open water. The gentle breeze cooled my skin as Iglided across the serene expanse. I marveled at the panoramic views of the lake and its surroundings, feeling a profound sense of tranquility and connection with nature.As the sun began to set, I made my way back to the shore. The sky was ablaze with vibrant hues of orange, pink, and purple, casting a warm glow over the lake. I sat on a bench and gazed out at the water, reflecting on the beauty and serenity I had experienced.Wuyang Lake is a truly enchanting destination thatoffers a respite from the hustle and bustle of city life.Its picturesque surroundings, serene atmosphere, and abundance of recreational activities make it an ideal place to relax, rejuvenate, and appreciate the wonders of nature.中文回答：踏青五日阳湖，恍若置身世外桃源。

A deep Chandra observation of the Centaurus cluster bubbles, filaments and edges

a r X i v :a s t r o -p h /0503154v 1 7 M a r 2005Mon.Not.R.Astron.Soc.000,000–000(0000)Printed 2February 2008(MN L A T E X style ﬁle v2.2)A deep Chandra observation of the Centaurus cluster:bubbles,ﬁlaments and edgesA.C.Fabian 1⋆,J.S.Sanders 1,G.B Taylor 2,3and S.W.Allen 1,21Institute of Astronomy,Madingley Road,Cambridge CB30HA 2Kavli Institute for Particle Astrophysics and Cosmology,Stanford University,382Via Pueblo Mall,Stanford,CA 94305-4060,USA 3National Radio Astronomy Observatory,Socorro,NM 87801,USA2February 2008ABSTRACT X-ray images and gas temperatures taken from a deep ∼200ks Chandra observation of the Centaurus cluster are presented.Multiple inner bubbles and outer semicircular edges are re-vealed,together with wispy ﬁlaments of soft X-ray emitting gas.The frothy central structure and eastern edge are likely due to the central radio source blowing bubbles in the intracluster gas.The semicircular edges to the surface brightness maps 32kpc to the east and 17.5kpc to the west are marked by sharp temperature increases and abundance drops.The edges could be due to sloshing motions of the central potential,or are possibly enhanced by earlier radio activity.The high abundance of the innermost gas (about 2.5times Solar)limits the amount of diffusion and mixing taking place.Key words:X-rays:galaxies —galaxies:clusters:individual:Centaurus —intergalactic medium 1INTRODUCTION The Centaurus cluster (Abell 3526)is X-ray bright,being the near-est cluster (redshift z =0.0104)with a 2–10keV luminosity ex-ceeding 5×1043erg s −1.Our earlier 31.7ks Chandra image of the Centaurus cluster revealed a complex structure in the inner-most few arcmin of the core,centred on the brightest cluster galaxy NGC 4696(Sanders &Fabian 2002).The iron abundance of thegas was found to peak at a radius of about 1arcmin from the cen-tre.The temperature drops from 3.5to about 1keV over this wholeregion.A plume-like structure swirls clockwise to the NE beyondwhich there is an abrupt temperature increase (i.e.a cold front).Thecentral X-ray emission is surrounded by marked dips in emission,or bubbles,which coincide with the complex radio source (Taylor,Fabian &Allen 2002).Previous X-ray observations (e.g.Allen &Fabian 1994)showa system with smooth,elliptical,X-ray isophotes,indicating thesystem is relatively relaxed.However,there is evidence for a cur-rent or past merger event (Allen &Fabian 1994;Churazov et al.1999;Furusho et al.2001;Dupke et al 2001)in the form of shiftsin X-ray isophote centroids with radius and bulk motions in the X-ray gas.A neighbouring subcluster,Cen 45centred on NGC 4709which is about 15arcmin E of NGC 4696,has a velocity whichis 1500km s −1higher than the main Centaurus cluster,Cen 30(Lucey,Currie &Dickens 1986).Observations of the Centauruscluster using ROSAT and ASCA show that the central region of the ⋆E-mail:acf@ Figure 1.Three colour image of the core of the cluster (24kpc from N to S).Emission between 0.3and 1keV is coloured red,1to 2keV green,and 2to 7keV blue.The image is 2m 21s from N to S which is almost 30kpc at the distance of NGC 4696.cluster is particularly rich in metals,with a large abundance gradi-ent (Fukazawa et al.1994;Ikebe et al.1998;Allen et al.2001).Cluster cores are in detail complex but provide us with an ob-servable analogue of the cooling and heating processes implicit in c0000RAS2 A.C.Fabian et alFigure2.Accumulatively-smoothed images of the core of the cluster in three energy bands.0.3-1.0(left),1.0-2.0(centre)and2.0-7.0(right).The images were smoothed to include a signal to noise ratio of10in the smoothing kernel.Each image is2m46s from N to S.Figure3.Upper:Detail of the X-ray image in the outer part of the core.Theimage is in the0.4to7keV band,smoothed with a Gaussian of∼1arcsec.Using an image smoothed with a Gaussian of∼15arcsec,we subtractedsome of the larger scale structure to improve contrast.Various features aremarked.the formation of massive galaxies.The nearness,intermediate tem-perature,short radiative cooling time and high metallicity make theCentaurus cluster an excellent candidate for studying these pro-cesses and also the enrichment of the intracluster gas.Here wepresent images of the Centaurus cluster from a recent200ks Chan-dra observation.We adopt H0=70km s−1Mpc−1which means that one arc-sec corresponds to210pc at the redshift of the Centaurus cluster.2THE DATAThe data presented here are based on Chandra OBSIDs504,5310,4954and4955.OBSID504wasﬁrst presented in Sanders&Fabian(2002).The standard LCA deep Chandra observation of the Centaurus cluster3Figure 4.Left:Projected,emission-weighted,temperature map of the cluster.Excluded point sources are marked by white discs.The uncertainties on the temperatures in individual regions containing 2500counts vary from ∼0.01keV in the coolest regions to around 0.5keV in the hottest regions.Right:Corresponding abundance map measured by ﬁtting spectra in regions containing 104counts.Two-temperature models were tested for each region and,where required by an F-test (at better than the 99per cent level),we have replaced the single temperature abundance by the corresponding two-temperature one.Two temperatures were need for most of the regions in the temperature map below 2keV .A b u n d a n c e (s o l a r)Temperature (keV)Figure 5.Distribution of abundance as a function of temperature.Abun-dances obtained from a two-temperature ﬁt are plotted in red using tempera-tures from the single-temperature ﬁt.The result of using a three-temperaturemodel for the apparent low abundance regions below 0.8keV is shown bythe blue star.inner parts of the ﬁlaments correspond to the optical ﬁlaments andFigure 6.Soft (0.3–0.8keV)X-ray image (left)of the absorbing disc galaxyseen in the red DSS image (right).Each image is 2.5arcmin from N to S.dust lane seen in NGC 4696(Fabian et al 1982;Sparks,Macchetto &Golombek 1989).Comparison with new H αimages of this re-gion will be presented elsewhere (Crawford et al.,in preparation).•In the 1–2keV band the holes corresponding to the radio lobes are very clear and above 2keV the rims of these ‘holes’or ‘bubbles’appear bright.The rims do not appear in projection to be hotter (Fig.4;conﬁrmed by a higher resolution temperature map)and are therefore not shocked.This is similar to results on bubbles found in the Perseus cluster (Fabian et al 2002,2003).Possible weak ripples in the X-ray surface brightness centred on the nucleus can be seen in Fig.3,particularly on the NE of the E edge (cf.Fabian et al 2003;Forman et al 2003).c 0000RAS,MNRAS 000,000–0004 A.C.Fabian etalFigure 7.Adaptively-smoothed whole band X-ray image (0.4–7keV)in red with overlaid 1.4GHz radio image in blue.The image is 125arcsec from top to bottom.•A loop of gas to the SE (Fig.2,left)does not coincide with any obvious radio structure (Figs.7and 8)and could either sur-round relativistic plasma where the electrons have aged to the ex-tent that they no longer radiate in the observed bands (a ghost bub-ble),or could just be a loop of cooler X-ray gas.A slight deﬁcit in this region seen in the harder X-ray bands (Figs.1and 2)suggests that it is most likely a ghost bubble.A larger loop to the NE ap-pears in the adaptively-smoothed image (Fig.7).Radio emission is leaking into the inner end (Fig.8),suggesting that it too is a ghost bubble.The lop-sided larger scale diffuse emission in the total 0.4–7keV band was apparent in the earlier image but is now seen much more clearly.It shows a semicircular edge to the E at 83arcsec (17.5kpc)from the nucleus (Fig.3)and a larger semicircular edge to the W at 153arcsec (32.1kpc).While the edge to the E is centred on the nucleus of NGC 4696,that to the W is centred 52arcsec (10.9kpc)to the W of the nucleus,suggesting that the gas there is in motion with respect to the nucleus.The edges are clearly evident in the projected temperature map (Fig.4)and emphasise that the temperature abruptly jumps there by almost 1keV .They appeared in the radial temperature proﬁles made from the earlier data (Sanders &Fabian 2002)to both E and W separately.The simplest explanation for them is as cold fronts,such as seen in other clusters (e.g.Markevitch 2000;Vikhlinin et al 2002).Separate deprojection of spectra across the edges to the E and W shows that the pressure across the edges is consistent with being continuous.The abundance drops across both edges;steeply in the case of the W edge (Fig.4),unlike the cold front in A496(Dupke &Bregman 2003).The sharp abundance change is similar to behaviour seen in NGC 507by Kraft et al (2004),although the edge there coincides with a radio lobe,which is not the case here.The large extent of the edges argues against them being simple cold fronts.Sloshing motions of the gas within the central potential well (e.g.Markevitch et al 2001)could account for them and for the E-W asymmetry of the appearance.However,the semicircular shape of the eastern one (see particularly Fig.3)suggests that this,at least,may have been shaped by disturbances from the nucleus.The radio source on the other hand appears to be moving tothe Figure 8.The VLA total intensity image at 330MHz is shown overlaid on the X-ray image (upper)and on a spectral index map (lower)with contours starting at 20mJy/beam and increasing by factors of 2.The restoring beam is 17.7×5.6arcseconds in position angle −4.3degrees.The radio spectral index (deﬁned S ν∝να)has been computed between 330and 1565MHz after convolving the 1565MHz image to the resolution of the 330MHz image.N,although that may just be an impression from its outer structure (Fig.8)which may be following the path of least resistance (the optical image of NGC 4696shows it signiﬁcantly ﬂattened in the N-S direction).The temperature and abundance maps (Fig.4)reveal that the core of the cluster consists of at least 4distinct parts.They are a)the region immediately around the nucleus,b)a high abundance region extending 18kpc to the end of the eastern plume,c)a quasi-spherical region of radius 32kpc with its centre displaced 11kpc toc 0000RAS,MNRAS 000,000–000A deep Chandra observation of the Centaurus cluster5the W of the nucleus,and d)the outer region.Each part occupies a different part of the abundance–temperature plane(Fig.5)with a) <1keV,b)1−2keV,c)2−3keV andﬁnally d)>3keV.In the present multi-temperature analysis,the abundance peaks at∼2.5Z⊙in b)and drops by about1Z⊙between b)and c)and c)and d).There cannot be any large turbulent or stochas-tic motions in the core or these high abundances would have been smoothed out.Following the work of Rebusco et al(2005),who have estimated the diffusion coefﬁcient D in the core of the Perseus cluster.we can obtain a limit from the much higher gradient seen in Centaurus.Assuming stochastic diffusion only,then steep gradi-ents over a distance d are smoothed out on a timescale of d2/D.If weﬁrst look at the outer,western edge and rely only on diffusion to smooth it and adopt a minimum time equal to the local crossing time of the structure of∼5×108yr then D<6×1028cm2s−1. This is smaller than the result,D∼2×1029cm2s−1,of Rebusco et al(2005).Since the region is displaced from the central galaxy it is unlikely that any current enrichment has a noticeable effect. Detailed modelling including metal enrichment should yield a tight constraint from the inner,high abundance,region.The above con-straint from the outer region means that the level of turbulence and stochastic motions in the Centaurus cluster is low(the product of velocity and lengthscale of the motions being∼3D).Smallscale motions need continual pumping or they would rapidly die out, temporarily heating the gas,as noted by Rebusco et al(2005).The lowest energy image reveals delicateﬁlaments of X-ray emitting gas which are only1–3arcsec(200–600pc)wide.The temperature of these structures is about0.7keV while the gas they are embedded in has a temperature of about1.5keV.Conduction is presumably much reduced and magneticﬁelds help maintain the integrity of the structures.In the very core around the nucleus,we can now see that the temperature drops down to less than0.7keV,with the inner region being multiphase.The whole temperature range detectable in the Centaurus cluster therefore exceeds a factor of5,which is signif-icantly larger that the factor of three seen in many other clusters (Peterson et al2003;but see Morris&Fabian2004).A disc galaxy to the SE of NGC4696(at RA124903.8, Dec-412027,J2000.0)can just be seen in silhouette in Fig.3 and,more clearly,in Fig.6.It has a radial heliocentric velocity of 3737km s−1(Dickens,Currie&Lucey1986),so lies in the Cen30 cluster,and is322-G93in the ESO/Uppsala catalogue.Photoelec-tric absorption by galaxies projected onto intracluster gas is also seen in the Perseus(Gillmon et al2003)and A2029(Clarke et al 2004)clusters.4DISCUSSIONThe inner region is complex with radio bubbles,ghost bubbles and coolﬁlaments.The’frothy’X-ray appearance of the centre resem-bles the centre of the Virgo cluster(Young et al2002;Forman et al 2003)which also has several inner bubbles.The region beyond is smoother but appears different to the East and West.In those direc-tions clear semicircular edges are seen.The one to the E is concen-tric with the nucleus indicating that it may have been triggered by a disturbance from there.The larger one to the W is centred west of the nucleus.Its shape suggests that some disturbance from the nucleus may produce it as well.The Western edge appears as a marked abundance drop,which is not easily accounted for,although large buoyant bubbles drag-ging iron-rich mattter outward,as seen in the Perseus cluster (Sanders,Fabian&Dunn2004),or fast-moving,outer gas sweep-ing past as a result of the ongoing merger with Cen45(which is not otherwise seen),could contribute.The dense,metal-rich centre of the Centaurus cluster is re-vealed as more complex than in previous observations.The radio source clearly has an impact immediately around the centre in the frothy bubble structure and the Eastern edge,although the long-term nature of the interaction and its contribution to the energy bal-ance of the central intracluster medium is elusive.Given that in equilibrium temperature contours follow equipotentials,the asym-metric temperature structure around the central galaxy NGC4696 means that some major part of the mass or gas distribution there is dynamically changing.5ACKNOWLEDGEMENTSThe National Radio Astronomy Observatory is operated by As-sociated Universities,Inc.,under cooperative agreement with the National Science Foundation.GBT acknowledges support for this work from the National Aeronautics and Space Administration through Chandra Award Number GO4-5135X issued by the Chan-dra X-ray Observatory Center,which is operated by the Smithso-nian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060. GBT also thanks the Institute of Astronomy for hospitality while working on this project.ACF and SWA thank the Royal Society for support.REFERENCESAllen S.W.,Fabian A.C.,1994,MNRAS,269,409Allen S.W.,Fabian A.C.,Johnstone R.M.,Arnaud K.A.,Nulsen P.E.J., 2001,MNRAS,322,589Anders E.,Grevesse N.,1989,Geochimica et Cosmochimica Acta53,197 Churazov E.,Gilfanov M.,Forman W.,Jones C.,1999,ApJ,520,105 Clarke T.E.,Blanton E.L.,Sarazin C.L.,2004,ApJ,616,178Dickens R.J.,Currie M.J.,Lucey J.R.,1986,MNRAS,220,679Dupke R.,Bregman J.N.,2001,ApJ,562,266Dupke R.,White R.E.,2003,ApJ,583,L13Fabian A.C.,Nulsen P.,Atherton P.,Taylor K.,1982,MNRAS,201,17P Fabian A.C.,Celotti A.,Blundell K.M.,Kassim N.E.,Perley R.A.,2002, MNRAS,331,369Fabian A.C.et al2003,MNRAS,344,43Forman W.et al2003,ApJ,submitted,astro-ph/0312576Fukazawa Y.,Ohashi T.,Fabian A.C.,Canizares C.R.,Ikebe Y.,Makishima K.,Mushotzky R.F.,Yamashita K.,1994,PASJ,46,L55Furusho T.,et al.,2001,PASJ,53,421Gillmon K.,Sanders J.S.,Fabian A.C.,2004,MNRAS,348,159Ikebe Y.,Makishima K.,Fukazawa Y.,Tamura T.,Xu H.,Ohashi T.,Mat-sushita K.,1999,ApJ,525,58Kraft R.P.,et al2004,ApJ,601,221Lucey J.R.,Currie M.J,Dickens R.J.,1986,MNRAS,221,453 Markevitch M.,et al2000,ApJ,541,542Markevitch M.,Vikhlinin A.,Mazzotta P.,2001,ApJ,562,L153Morris R.G.,Fabian A.C.,2004,MNRAS submitted(astro-ph/) Peterson,J.R.,et al2003,ApJ,590,207Rebusco P.,Churazov E.,B¨o hringer H.,Forman W.,2005,MNRAS sub-mitted,astro-ph/0501141Sanders J.S.,Fabian A.C.,2002,MNRAS,331,273Sanders J.S.,Fabian A.C.,Dunn R.J.H.,2004,MNRAS,submitted Sparks W.,Macchetto F.,Golombek D.,1989,ApJ,345,153Taylor G.B.,Fabian A.C.,Allen S.W.,2002,MNRAS,334,769 Vikhlinin A.,Markevitch M.,Murray S.S.,2001,ApJ,551,160c 0000RAS,MNRAS000,000–0006 A.C.Fabian et alYoung A.J.,Wilson A.S.,Mundell C.G.,2002,ApJ,579,560c 0000RAS,MNRAS000,000–000。

VLA H53alpha and H92alpha line observations of the central region of NGC 253

a rXiv:as tr o-ph/6323v11Mar26VLA H53αand H92αline observations of the central region of NGC 253C.A.Rodr´ıguez-Rico 1,2c.rodriguez@astrosmo.unam.mx W.M.Goss 2mgoss@ J.-H.Zhao 3jzhao@ Y.G´o mez 1y.gomez@astrosmo.unam.mx K.R.Anantharamaiah 4ABSTRACT We present new Very Large Array (VLA)observations toward NGC 253of the recombination line H53α(43GHz)at an angular resolution of 1.′′5×1.′′0.The free-free emission at 43GHz is estimated to be ∼100mJy,implying a star formation rate of ∼1.3M ⊙yr −1in the nuclear region of this starburst galaxy.A reanalysis is made for previously reported H92αobservations carried out withangular resolution of 1.′′5×1.′′0and 0.′′36×0.′′21.Based on the line and continuum emission models used for the 1.′′5×1.′′0angular resolution observations,the RRLs H53αand H92αare tracers of the high-density (∼105cm −3)and low-density (∼103cm −3)thermally ionized gas components in NGC 253,respectively.The velocity ﬁelds observed in the H53αand H92αlines (1.′′5×1.′′0)are consistent.Thevelocity gradient in the central∼18pc of the NE component,as observed in boththe H53αand H92αlines,is in the opposite direction to the velocity gradientdetermined from the CO observations.The enclosed virial mass,as deducedfrom the H53αvelocity gradient over the NE component,is∼5×106M⊙in thecentral∼18pc region.The H92αline observations at high angular resolution(0.′′36×0.′′21)reveal a larger velocity gradient,along a P.A.∼−45◦on the NEcomponent,of∼110km s−1arcsec−1.The dynamical mass estimated using thehigh angular resolution H92αdata(∼7×106M⊙)supports the existence of anaccreted massive object in the nuclear region of NGC253.Subject headings:starburst galaxies,radio recombination lines,NGC2531.INTRODUCTIONNGC253is one of the nearest(∼2.5Mpc)and brightest starburst galaxies,catalogued as an SAB(s)c galaxy(de Vaucouleurs et al.1976).This galaxy has an inclination of∼79◦with respect to the line-of-sight with major axis located at a position angle(P.A.)of51◦, also containing a bar-like feature tilted by18◦with respect to the major axis(Pence1981). Observations of NGC253have been carried out in the radio(Turner&Ho1985;Ulvestad& Antonucci1997;Mohan,Anantharamaiah,&Goss2002;Mohan,Goss,&Anantharamaiah 2005;Boomsma et al.2005)infrared(Engelbracht et al.1998),optical(Forbes et al.2000; Arnaboldi et al.1995)and X-ray(Weaver et al.2002)wavelengths.Radio observations, which are not aﬀected by dust absorption,are an excellent tool to study the structure and kinematics of the nuclear region of NGC253.Observations in the21-cm line(Boomsma et al.2005)reveal extra-planar motions of HI that occur at a large scale of up to12kpc.High angular resolution radio continuum observations(Ulvestad&Antonucci1997)have revealed a number(>60)of compact sources in the central300pc of this galaxy,supporting the scenario of a massive star formation episode occurring in the center of NGC253.Nearly half of these compact continuum sources are dominated by thermal radio emission from HII regions(Turner&Ho1985;Antonucci&Ulvestad1988;Ulvestad&Antonucci1997).The radio continuum and radio recombination line emission,observed at high angular resolution, have been modeled using diﬀerent density components for the ionized gas(Mohan,Goss,& Anantharamaiah2005).The emission models suggest the existence of both low(∼103cm−3) and high-density(>104cm−3)ionized gas in the central region of NGC253.On the other hand,the most luminous source(5.79-0.39)is unresolved(<1pc)at22GHz suggesting the existence of an AGN in the center of this galaxy(Ulvestad&Antonucci1997).Observations of broad H2O maser line emission(≥100km s−1)near this radio continuum source hasbeen invoked as further evidence of the presence of a massive object in NGC253(Nakai et al.1995).Mohan,Anantharamaiah,&Goss(2002)modeled the VLA continuum and radio recombination line(RRL)emission for the nuclear region of NGC253and favor an AGN as the source responsible for the ionization.Observations of hard X-ray emission toward the core of NGC253were also interpreted as evidence of AGN activity(Weaver et al.2002).The bar-like structure wasﬁrst observed toward NGC253in the near-infrared(NIR), covering the inner150′′region of the galaxy(Scoville et al.1985;Forbes&Depoy1992). The existence of the stellar bar is supported by the observed morphology at optical and mid-infrared frequencies(Forbes&Depoy1992;Pi˜n a et al.1992).A counterpart of the stellar bar in NGC253has been found in CO(Canzian,Mundy,&Scoville1988),HCN (Paglione,Tosaki,&Jackson1995)and CS(Peng et al.1996).Observations in the RRL H92α(Anantharamaiah&Goss1996)at an angular resolution of1.′′8×1.′′0reveal a velocity ﬁeld that is discrepant with the CO,CS and HCN observations.Anantharamaiah&Goss (1996)proposed that the kinematics observed in the H92αcould result from a merger of two counter-rotating disks.The observed H92αand CO line velocityﬁelds were modeled by Das, Anantharamaiah&Yun(2001)using a bar-like potential for NGC253,which is in reasonable agreement with the observed H92αline velocityﬁeld.However,this kinematical model can only reproduce the velocityﬁeld of the CO and CS and does not agree with the H92αRRL observations.Based on the discrepancy of the CO and the ionized gas kinematics,Das, Anantharamaiah&Yun(2001)proposed that the accretion of a compact object(∼106M⊙) about107years ago could account for the velocityﬁeld observed in the H92αRRL.Paglione et al.(2004)observed the CO emission at3′′angular resolution for the inner region and modeled the kinematics of the molecular gas using a bar potential,concluding that motions of the CO gas in the central150pc are consistent with a bar potential and report evidence of the existence of an inner Lindblad resonance(ILR).Previous interferometric observations of RRLs have been made at low frequencies(e.g.∼8.3GHz,H92α).VLA observations at1.′′5×1.′′0angular resolution were used by Anan-tharamaiah&Goss(1996)to study the kinematics of NGC253;Mohan et al.(2002,2005) used the VLA observations at1.′′5×1.′′0and0.′′3angular resolutions to determine the phys-ical properties of the ionized gas in NGC253.In this paper we analyse the kinematics of the ionized gas in the nuclear region of NGC253using high frequency RRL observations (∼43GHz)and the high angular resolution observations(at0.′′3)in the RRL H92α.Also we use the VLA observations in the RRL H53αand the43GHz radio continuum,along with previously reported H92αline and8.3GHz radio continuum observations(Mohan et al.2005),in order to estimate the physical properties of the ionized gas.This paper is complementary to the results summarized by Mohan et al.(2005).Section2presents the observations and data reduction,while§3presents the results for the H53αand H92αRRLs.In subsection4.1,a model for the emission of the RRLs H53αand H92αas well as for the radio continuum at43and8.3GHz is presented.Subsection4.2analyzes the kinematics for the ionized gas in the center of NGC253and§5presents the conclusions.2.VLA Observations.2.1.H53αline.The H53αline(νrest=43309.4MHz)was observed in the CnD conﬁguration of the VLA on2003,January18,19and20.We used cycles with integration times of10min on NGC253and1min on the phase calibrator J0120-270(∼0.7Jy).Four frequency win-dows(LOs)were used to observe the RRL H53α,centered at42885.1,42914.9,42935.1,and 42964.9GHz.For each frequency window,the on-source integration time was∼2hrs,using the mode of15spectral channels with a channel separation of3.125MHz(∼22km s−1). The data calibration was carried out for each frequency window using the continuum chan-nel,consisting of the central75%of the band.Theﬂux density scales were determined from observations of J0137+331(3C48;0.54Jy).The bandpass response of the instrument was corrected using observations of J0319+415(3C84;∼7.5Jy).The parameters of the observations are summarized in Table1.In order to track reliably the phase variations in-troduced by the troposphere,the calibration of the data was performed correcting for the phases in aﬁrst step and subsequently correcting for both amplitude and phase.The line data were further calibrated using the solutions obtained by self-calibrating the continuum channel of each frequency window.The radio continuum images were obtained by combining the continuum channels of each frequency window using the task DBCON from AIPS,and the self-calibration method was also applied to this combined data.The H53αline cubes and the43GHz continuum image were made using a natural weighting scheme and then convolved to obtain a Gaussian beam of1.′′5×1.′′0(P.A.=0◦).The combination of the diﬀer-ent frequency windows was made following a similar method to that used for the H53αline observed toward M82(Rodr´ıguez-Rico et al.2004):(1)the line data from each frequency window were regridded in frequency using the GIPSY reduction package,(2)before com-bining the four LOs into a single line cube,the continuum emission was subtracted for each frequency window using the AIPS task IMLIN with a zero order polynomialﬁt based on the line free channels,and(3)the four line cubes(after subtraction of the continuum)were combined into a single line cube.The total line bandwidth,after combining all the windows, is about150MHz(1000km s−1).The line data cube was Hanning-smoothed using the task XSMTH in AIPS to reduce the Gibbs eﬀect and theﬁnal velocity resolution is∼44km s−1.2.2.H92αline.We also present previously reported observations of the RRL H92α(νrest=8309.4MHz) at1.′′5×1.′′0,P.A.=0◦(Anantharamaiah et al.1996)and0.′′36×0.′′21,P.A.=−3◦(Mohan et al.2005,2002)angular resolutions toward NGC253.The H92αRRL images at1.′′5×1.′′0 angular resolution were produced by combining observations carried out in the B(August 31and Sept01,1990),C(May14and23,1988)and D(July01and19,1988)conﬁgurations of the VLA.In order to obtain the same HPFW beam as the H53αline cube,the H92αline cube was made using these’B+C+D’combined data applying a natural weighting scheme. Anantharamaiah&Goss(1996)have already used these’B+C+D’combined observations to analyze the kinematics of the ionized gas in the central10′′of NGC253with an angular resolution of1.′′8×1.′′0,P.A.=10◦.The higher angular resolution(0.′′36×0.′′21,P.A.=−3◦) observations of the H92αline toward NGC253were made with the VLA in the A array (July9and12,1999)and have been previously reported by Mohan,Anantharamaiah,& Goss(2002).Recently,Mohan,Goss,&Anantharamaiah(2005)used these H92αdata along with observations in the RRLs H75αand H166αdata to model the RRL and the radio continuum emission in order to determine the physical parameters of the ionized gas.In this paper we use these high angular resolution observations to study the kinematics of the ionized gas in the nuclear5′′region of NGC253.Because of the diﬀerent spectral line grid of the H92αhigh angular resolution observations and the H92α’B+C+D’data,a combined dataset’A+B+C+D’was not produced.For the H92αline observations,the phase calibrator was J0118-216and the bandpass calibrator was J2253+161.A spectral mode with31channels was used.The continuum images were obtained by averaging the data in the central75%of the total band.The continuum data were processed using standard calibration and self-calibration procedures. The calibration and self-calibration used for the continuum data were then applied to the line data.All the images were made in the AIPS environment.The line images were Hanning-smoothed to reduce the Gibbs eﬀect and the velocity resolution is56.4km s−1. Further observational details are summarized by Mohan,Anantharamaiah,&Goss(2002) and Mohan,Goss,&Anantharamaiah(2005).3.RESULTSFigure1shows the radio continuum emission of NGC253at43GHz with an angular resolution of1.′′5×1.′′0,P.A.=0◦(1′′≃12pc).The integrated43GHz continuumﬂux density is360±20mJy,obtained by integrating theﬂux density over the nuclear30′′region using the task IRING in AIPS.The radio continuum image at43GHz shows two radiocontinuum components,NE and SW,in addition to extended emission(see Figure1).The continuum peak position of the NE component,α(J2000)=00h47m33.s17±0.s01,δ(J2000)=−25◦17′17.′′4±0.′′1,coincides within0.′′2with the position of the compact source5.79-39.0 (Ulvestad&Antonucci1997).Figure2shows the H53αvelocity-channel images of NGC253with an angular resolution of1.′′5×1.′′0(P.A.=0◦).The H53αline emission is detected toward both the NE and SW continuum components above a3σlevel(∼2mJy).The ionized gas is observed in the H53αline at heliocentric velocities that range from17to345km s−1.The velocity-integrated H53αline emission(moment0)is shown in Figure3superposed on the moment0of the H92αline.There is good correspondence between the integrated line emission of the RRLs H53αand H92α.In addition,the peak position of the integrated H53αline emission is in agreement with the peak position of the43GHz radio continuum image.In the H53αline images,both the NE and SW components are spatially resolved only along the major axis.Figure4shows the H53αline spectrum integrated over the central10′′region of NGC253. Byﬁtting a Gaussian,the estimated central heliocentric velocity is210±10km s−1,the FWHM of the line is230±20km s−1and the peak lineﬂux density is21±2mJy.The resultingﬁt is shown in Figure4along with the residuals to theﬁt.The central velocity is in agreement with previous estimates in the optical(225±5km s−1;Arnaboldi et al. 1995)and IR(230±10km s−1;Prada,Guti´e rrez&McKeith1998).The velocity integrated H53αlineﬂux density determined from our observations is0.69±0.09×10−20W m−2,in agreement with the previous measurement of0.94±0.38×10−20W m−2derived from single-dish observations(Puxley et al.1997).A Gaussian function was also used to determine the characteristics of the spectra obtained by integrating over the NE and SW regions.Table2 lists the results for the total integrated H53αline emission proﬁle,as well as for proﬁles that correspond to the NE and SW components.The values listed for the H53αline are peak ﬂux density S L,FWHM,the heliocentric velocity V Hel and the velocity integrated H53αline emission.Figure5shows the velocityﬁeld(moment1)of the H53αline at an angular resolution of1.′′5×1.′′0(P.A.=0◦).Figure6shows the H92αvelocityﬁeld made using the’B+C+D’data of Anantharamaiah&Goss(1996)at the same angular resolution.The velocityﬁeld of the ionized gas as observed in the H53αline agrees with observations of the RRL H92α(see section4.2for a detailed comparison).In the NE component of NGC253the red-shifted gas is observed toward the NW and the blue-shifted gas toward the SE.In the region located S of the radio continuum peak,there is a blue-shifted component that is more apparent in the H53αline than in the H92αline.A detailed comparison between the line proﬁles of the H53αand H92αin this region shows that the H53αline is broader than the H92αline by∼50km s−1and there is a relative velocity shift between these two RRLs of∼30km s−1.In the elongated SW component,the red-shifted gas is located at the SW and the blue-shifted gas is at the NE.The velocity gradient was measured,at1.′′5×1.′′0angular resolution,along the major(P.A.=52◦)and nearly along the minor(P.A.=−45◦)axis for both RRLs the H53αand H92α.The H53αvelocity gradient along the major axis of NGC253(measured over the NE component)is12±3km s−1arcsec−1,comparable to the corresponding H92αvelocity gradient(∼11km s−1arcsec−1).The velocity gradients measured in the RRLs H53αand H92α(both at1.′′5×1.′′0)along the P.A.=−45◦are42±8km s−1arcsec−1and 24±2km s−1arcsec−1,respectively.Figure7shows the H92αvelocityﬁeld at an angular resolution of0.′′36×0.′′21(P.A.=−3◦).At this angular resolution,the H92αline emission is detected only toward the NE component with an angular size of∼0.′′6(7pc).Based on these H92αdata,a larger velocity gradient of110±20km s−1arcsec−1is measured along a P.A.≃−45◦.This velocity gradient is about a factor of four larger than the velocity gradient estimated using the lower angular resolution H92αobservations(1.′′5×1.′′0).The lower velocity gradient measured in the low angular resolution image of H92α(1.′′5×1.′′0)is due to a beam dilution eﬀect.By convolving the high angular resolution data of the H92αwith a Gaussian beam of1.′′5×1.′′0angular resolution,the velocity gradient measured along the P.A.=−45◦is consistent with the lower angular resolution H92αdata.4.DISCUSSION4.1.Models for the radio continuum and recombination line emissionIn Table3,we summarize the43GHz continuumﬂux density measurement along with previous measurements(5−300GHz)for the central30′′region of NGC253.Theseﬂux density values have been used to determine the relative contributions from free-free,syn-chrotron and dust emission.At frequencies<50GHz,the relative contributions of free-free and non-thermal emission are dominant compared to the thermal dust emission.However, at frequencies>50GHz,the dust contribution is more signiﬁcant.The estimated contri-bution of the thermal free-free emission at43GHz is∼140mJy,while the non-thermal emission accounts for∼220mJy.These values were obtained assuming that the thermal continuum free-freeﬂux density shows S free−free(ν)∝ν−ing the observedﬂux den-sity measurements of the radio continuum in the range of5−98GHz,and following the procedure used by Turner&Ho(1983),the spectral index for the non-thermal emission is αsynchrotron=−0.73±0.06.After subtracting the free-free and non-thermal emission from the total continuum emission over the5−300GHz frequency range,we obtain the spectralindex value for the dust emissionαdust=3.9±0.2.Figure8shows the contribution from thermal free-free,synchrotron and thermal dust emission along with the total radio contin-uum over the frequency range5to300GHz.The thermal free-free radio continuumﬂux density at43GHz may be used to estimate the ionization rate(N Lyc)from NGC253using (Schraml&Mezger1969;Rodr´ıguez et al.1980),N LycmJy T e4.9GHz0.1 Das the volume of the total line emission,assuming spherical HII regions.The models suggest that the thermally ionized gas in the NE component consists of a collection of extended(∼1−4pc)low-density(∼102−103cm−3)HII regions and compact (∼0.01−0.06pc)high-density(∼105−106cm−3)HII regions.In order to reproduce the observations,the mass of ionized gas in the low-density component must be a factor of∼103larger than the mass of ionized gas in the high-density component.The ionized gas in the SW region also consists of low-and high-density HII regions,characterized by n e≃102cm−3and n e≃105−106cm−3.Table4lists the physical parameters of these HII regions:the electron temperature(T e),electron density(n e),size,emission measure(EM), mass of ionized gas,continuum optical depth(τc)at8.3and43GHz,departure coeﬃcients (b n andβn=1−(kT e/hνL)d ln b n/dn,where n is the quantum number)for the H53αand H92αRRLs,the contribution of free-free emission and the Lyman continuum photons rate.The second and third columns list these parameters for the low and high-density HII regions on the NE component.The fourth andﬁfth columns list the corresponding parameters for the SW component.Based on these models,the RRL H92αarises mainly as externally stimulated line emission from the extended low-density(∼103cm−3)HII regions, withβn<−20.The thermal free-free contribution from both the low-and high-density component to the total observed continuum emission ranges from∼30%to∼80%.The total mass of thermally ionized gas in each component(NE and the SW)is∼103M⊙.The Lyman continuum emission rate of5.9×1052s−1obtained from the RRL emission models(see Table4)is consistent with7×1052s−1,obtained from the continuum emission models (shown in Figure8).The Lyman continuum emission rates for the NE and SW components (listed in Table4)were obtained only for regions where H53αline emission was detected. On the other hand,the value of7×1052s−1was estimated by integrating over the central 30′′region,which explains the slightly diﬀerent results.The results obtained for the low-density gas component for the NE component of NGC253are in agreement with the results obtained by Mohan,Goss,&Anantharamaiah(2005)for the15pc region,observed with higher angular resolution observations(∼0.′′3)and using VLA H166α,H92αand H75αline data.Even though the mass contribution of the high density HII regions is only∼1%of the total HII mass,this feature contributes∼40%of the total H53αline emission.As noted before by Mohan,Goss,&Anantharamaiah(2005),high angular resolution observations are essential in the determination of the physical parameters of both low and high-density HII regions.In addition to high angular resolution,high frequency observations (e.g.H53α)are required to determine the properties of the high-density(∼105cm−3)HII regions.Non-LTE eﬀects are important,leading to an enhancement of the line emission by afactor of∼2.Thus,the results obtained assuming LTE conditions overestimate the number of HII regions(and also the SFR)that must exist in NGC253.4.2.KinematicsThe previous H92αline observations at1.′′8×1.′′0angular resolution(Anantharamaiah &Goss1996)revealed velocity gradients of∼11km s−1arcsec−1and∼18km s−1arcsec−1 along the major axis and minor axis,respectively.A qualitative comparison of the velocity ﬁeld observed in the H53αline and the previously reported H92αline velocityﬁeld reveals kinematical behaviors that are consistent,i.e.the regions with red-shifted and blue-shifted ionized gas coincide(see Figs.5and6).The coincidence of the red-and blue-shifted regions in the H53αand H92αvelocityﬁelds implies that both the low-and high-density ionized gas components rotate in the same sense.In order to compare in detail the kinematics of the ionized gas as observed in the H53αand the H92αlines,we constructed PV diagrams along the major axis(P.A.=52◦)using the task SLICE in GIPSY.These PV diagrams are shown in Figure9;the white line is the resultingﬁt to the velocity gradient of11km s−1arcsec−1.The same procedure was used to obtain PV diagrams along the P.A.=−45◦,shown in Figure10;the white lines are the resultingﬁts to the H92αvelocity gradient(24km s−1arcsec−1)and the H53αvelocity gradient(42km s−1arcsec−1).In Figure10we also show the H92αand H53αspectra superimposed at diﬀerent oﬀset positions from the central source(5.79-39.0);these spectra were normalized based on the peak lineﬂux densities.By inspection of the diﬀerent spectra obtained at the negative oﬀset positions(between−0.′′6and−0.′′9in Figure10),a relative velocity shift(∼30±5km s−1)is observed between the peakﬂux density of the H53αand the H92αlines.Based on the line emission models,these two RRLs trace diﬀerent density components(see section4.1).The small velocity shift between these two RRLs on the NE component suggests that each density component has slightly diﬀerent kinematics.4.2.1.Gaseous bar structure,outﬂow or an accreted objectObservations at IR wavelengths have revealed the existence of a gaseous bar in NGC253 (Scoville et al.1985).In a bar potential the gas follows two types of orbits,x1and x2.The x1 (bar)orbits are those extended along the major axis of the bar and the x2(anti-bar)orbits are those oriented perpendicular to the bar major axis.In the case of NGC253,the x1and x2orbits would be oriented on the plane of the sky at P.A.of∼70◦and∼45◦,respectively.In the H53αand H92αRRL images(at1.′′5×1.′′0angular resolution)the orientation of the largest velocity gradient is nearly perpendicular to the orientation of the x2orbits.Since the ionized gas on the NE component rotates in an opposite sense compared to the CO (Anantharamaiah&Goss1996;Das,Anantharamaiah&Yun2001),a simple bar potential does not account for the diﬀerences observed between the velocityﬁelds of the RRLs(H92αand H53α)and CO.A secondary bar inside the primary bar may be invoked to explain the kinematics observed in the center of NGC253.However,further observations and modeling are required to investigate the existence of this secondary bar.Weaver et al.(2002)proposed the presence of a starburst-driven nuclear outﬂow col-limated by a dusty torus,based on X-ray observations of NGC253.In this model,the thermally ionized gas in the center of NGC253should be distributed in both a starburst ring and a starburst-driven outﬂow(Weaver et al.2002).Observations of the RRL H92αtoward the starburst galaxy M82(Rodr´ıguez-Rico et al.2004),have proben that RRLs may be used to study the ionized gas associated with galactic outﬂows.The largest velocity gradient observed in the RRL H92αis oriented nearly along the minor axis of NGC253 (P.A.=−45◦).Based on this orientation and assuming the H92αRRL in the NE component traces the ionized gas in the outﬂow,the receding side of this outﬂow would be on the NW and the approaching side on the SE.If this is the case all the observed ionized gas would be tracing the outﬂow,explaining the diﬀerent rotation sense between the CO and the ionized gas.However,it seems unlikely that all the ionized gas is associated with the outﬂow.Das,Anantharamaiah&Yun(2001)propose that the kinematics of the ionized gas traced by the H92αRRL can be explained if there is an accreted object with mass of ∼106M⊙.The CO gas which traces the galactic disk of NGC253is moving in an opposite sense compared to the ionized gas that may be associated with the compact object.Based on the H53αvelocity gradient(∼42km s−1arcsec−1)along the minor axis of the NE component (∼30pc),the inferred dynamical mass is∼5×106M⊙.This mass estimate is consistent with that of the accreted object proposed by Das,Anantharamaiah&Yun(2001).The existence of a compact object is further supported by the higher angular resolution(0.′′36×0.′′21)H92αobservations(Figure7),revealing a larger velocity gradient(∼110km s−1arcsec−1,at P.A.≃−45◦)over the central∼0.′′6(7pc).This H92αvelocity gradient of∼110km s−1arcsec−1 implies a dynamical mass of∼7×106M⊙,similar to the mass determined from the1.′′5×1.′′0 angular resolution observations of the RRLs H53αand H92α.The∼7×106M⊙dynamical mass is based on observations over a region a factor of three times smaller than that observed in the1.′′5×1.′′0angular resolution images.The estimated dynamical mass(∼7×106M⊙)for the nuclear region of NGC253is comparable to that of the compact source at the nucleus of our galaxy(∼4×106M⊙,Ghezet al.2005).This mass estimate of∼7×106M⊙for the central region of NGC253could exist in the form of a large number of stars combined with ionized gas and may also contain an AGN.If the Lyman continuum photons rate(∼7×1052s−1)is mainly due to O5stars, each emitting∼5×1048s−1,then there must be∼104O5stars in the NE component. Using Salpeter’s initial mass function and a mass range of0.1−100M⊙,the total mass in stars in the NE component is∼107M⊙.The ionized gas could be gravitationally bounded by the stars and consequently the black hole mass would be≤107M⊙.The existence of an AGN has been proposed from radio continuum observations(Turner&Ho1985;Ulvestad &Antonucci1997)and RRL H92αobservations(Mohan,Anantharamaiah,&Goss2002). Radio continuum observations(1.3to20cm),reveal that the strongest radio source5.79-39.0 has a brightness temperature>40,000K at22GHz and is unresolved(<1pc,Ulvestad and Antonucci1997).Broad(>100km s−1)H2O maser line emission is observed toward the nuclear regions supporting the existence of a massive object in the center of NGC253 (Nakai et al.1995).In order to account for the diﬀerent kinematics observed for the ionized and the molec-ular gas,two possible scenarios can be proposed:(1)a dense object that is accreted into the nuclear region of NGC253,(2)the ionized gas is moving in a starburst-driven outﬂow and/or(3)a secondary bar exists within the primary bar,as proposed for other galaxies (Friedli&Marinet1993).The accreted object model is supported by the high angular res-olution H92αobservations;the estimated dynamical mass of∼7×106M⊙is concentrated in a≤7pc region and the ionized gas traced by the RRLs moves in the opposite direction compared to the larger scale CO.In the RRLs H53αand H92α,weﬁnd no evidence that conﬁrms the existence of a secondary bar.An S-shape in the velocityﬁeld is characteristic of a bar(Anantharamaiah&Goss1996).Thus,for a secondary bar a second S-shaped pattern would be observed in the velocityﬁeld which is not appreciated in the H92αvelocity structure(see Figure7).However,this scenario cannot be ruled out and higher angular and spectral resolution observations are necessary to discern between these three models.5.CONCLUSIONS.The H53αRRL and radio continuum at43GHz were observed at high angular resolution (1.′′5×1.′′0)towards NGC253.We have also reanalyzed previous observations of the RRL H92αmade at an angular resolutions of1.′′5×1.′′0(Anantharamaiah&Goss1996)and 0.′′36×0.′′21(Mohan,Anantharamaiah,&Goss2002).Based on the43GHz radio continuumﬂux density and previous measurements at lower and higher frequencies,we have estimated the contribution from free-free emission。

英汉海洋科学名词

Australia-Antarctic Rise 澳大利亚-南极海隆
autecology 个体生态学
authigenic sediment 自生沉积
autoinhibitory substance 自体抑制物质
autotroph 自养生物
ahermatypic coral 非造礁珊瑚
air gun 气枪
air lifting 气举
air-born substances 气源物质
airborne infrared radiometer 机载红外辐射计
air-sea boundary process 海-气边界过程
"Arctic Water, North Polar Water " 北极水
arc-trench-basin system 沟弧盆系
armor block 护面块体
armored diving 铠装潜水
artificial island 人工岛
beach cusp 滩角
beach cycle 海滩旋回
beach face 滩面
beach nourishment 人工育滩
beach profile 海滩剖面
beach ridge 滩脊
beach rock 海滩岩
beam trawl 桁拖网
abiotic zone 无生命带
abrasion platform 海蚀台地
absolute salinity 绝对盐度
abundance 丰度
abyssal circulation 深渊环流
abyssal clay 深海粘土
abyssal fauna 深渊动物

克隆巴赫系数英文

IntroductionKrippendorff's alpha coefficient, a widely recognized statistical measure in content analysis, is an essential tool for assessing the reliability of coding or categorization schemes employed in qualitative and quantitative research. Developed by Klaus Krippendorff, this coefficient offers a rigorous, comprehensive, and versatile approach to evaluating inter-rater agreement across multiple coders and various data types, including nominal, ordinal, interval, and ratio scales. This extensive analysis aims to delve into the multifaceted nature of Krippendorff's alpha, elucidating its significance in maintaining high-quality and stringent standards in research, particularly in light of its methodological robustness, versatility, sensitivity, and applicability across diverse disciplines.Methodological Robustness: Ensuring Data Integrity and ConsistencyOne of the primary strengths of Krippendorff's alpha lies in its methodological robustness, which contributes significantly to upholding high-quality research standards. Unlike simpler measures like percent agreement or Cohen's kappa, which may be prone to inflated estimates due to chance agreement, Krippendorff's alpha accounts for both random and systematic coder disagreements, providing a more accurate reflection of true inter-rater reliability.Firstly, it calculates expected disagreement based on the marginal distributions of the codes assigned, thereby adjusting for the probability of chance agreement that can arise from unequal code frequencies or imbalanced data. This feature ensures that the observed agreement among coders is not merely a result of chance, but rather reflects a genuine consensus on the coding scheme.Secondly, Krippendorff's alpha is adaptable to missing data, allowing researchers to handle incomplete coding without discarding valuable observations or resorting to ad-hoc imputation methods. By incorporating missing values into its calculation, it acknowledges the reality of incomplete coding in real-world research scenarios while still providing a reliable estimate of inter-rater agreement.Versatility Across Data Types and Analytical FrameworksThe versatility of Krippendorff's alpha is another key aspect that bolsters its utility in maintaining high-quality research standards. It is applicable to various data types, including nominal, ordinal, interval, and ratio scales, making it suitable for diverse research contexts where different levels of measurement are employed. This flexibility enables researchers to assess inter-rater reliability consistently, regardless of whether they are analyzing categorical variables, ordinal ratings, or continuous measurements.Furthermore, Krippendorff's alpha is agnostic to the analytical framework or theoretical perspective guiding the research. Whether the study employs a deductive, inductive, or abductive approach, or is grounded in qualitative, quantitative, or mixed-methods research designs, the coefficient remains a relevant and reliable measure of inter-rater agreement. This universality fosters cross-disciplinary dialogue and allows for meaningful comparisons between studies employing different methodologies, contributing to the overall rigor and standardization of research practices.Sensitivity to Coding Complexity and Sample SizeKrippendorff's alpha is highly sensitive to both the complexity of the coding task and the sample size, ensuring that it accurately reflects the challenges faced by coders and the adequacy of the data for drawing reliable conclusions. In complex coding tasks with many categories or intricate decision rules, the coefficient will naturally tend to be lower due to the increased potential for disagreement among coders. This responsiveness to coding complexity encourages researchers to refine their coding schemes, provide clearer guidelines, or consider alternative analytical approaches when faced with low reliability scores.Regarding sample size, Krippendorff's alpha is known to converge to a stable value as the number of units coded increases, providing a more accurate estimate of inter-rater reliability with larger datasets. This property discourages researchers from drawing premature conclusions based on small samples andpromotes the collection of sufficient data to ensure reliable results.Applicability Across Disciplines and Research ContextsThe broad applicability of Krippendorff's alpha across various disciplines and research contexts further underscores its role in maintaining high-quality, standardized research practices. It has been widely adopted in fields such as sociology, psychology, communication studies, linguistics, anthropology, and information science, among others, for assessing the reliability of coding in content analysis, discourse analysis, sentiment analysis, and textual data mining.In these diverse settings, Krippendorff's alpha serves as a common metric for evaluating inter-rater agreement, facilitating comparisons across studies, and promoting the development of standardized coding practices within each discipline. Moreover, its ability to accommodate multivariate data structures, such as dyadic or triadic interactions, and its compatibility with hierarchical or clustered data, makes it suitable for complex research designs that often characterize interdisciplinary research.ConclusionKrippendorff's alpha coefficient embodies the high-quality and stringent standards required in contemporary research through its methodological robustness, versatility across data types and analytical frameworks, sensitivity to coding complexity and sample size, and broad applicability across disciplines and research contexts. By offering a rigorous, comprehensive, and adaptable measure of inter-rater agreement, it empowers researchers to assess the reliability of their coding schemes, refine their analytical strategies, and contribute to the standardization and harmonization of research practices across diverse fields. As such, Krippendorff's alpha stands as a cornerstone of qualitative and quantitative research, underpinning the pursuit of scientific rigor, accuracy, and reproducibility in the face of ever-evolving research challenges and complexities.。

长翅型白背飞虱雌成虫翅的超微特征

第 63 卷第 1 期2024 年 1 月Vol.63 No.1Jan.2024中山大学学报（自然科学版）（中英文）ACTA SCIENTIARUM NATURALIUM UNIVERSITATIS SUNYATSENI长翅型白背飞虱雌成虫翅的超微特征*伍俭儿，梁安文，冯博，胡杨，王方海中山大学生命科学学院，广东广州 510275摘要：白背飞虱Sogatella furcifera为水稻重要害虫，长翅型成虫能够远距离飞行迁移，扩散其危害的范围。

本研究利用扫描电镜观察研究了长翅型白背飞虱雌成虫翅的超微特征，发现：前、后翅的翅面中间薄而边缘厚，翅中部到端部的边缘有叠起的褶皱，前翅背面翅面上均匀地分布着许多小刺状突起，长度为（3.07±0.48）μm，而后翅背腹两面均着生有许多小刺状突起。

前翅的背面和腹面都存在毛形感器样结构，根据形态可分为TS-I和TS-Ⅱ两种：TS-I分布于腹面翅基部的翅脉处且与翅脉垂直，没有明显的基窝，数量为（4±1.41）根，长为（31.80±2.43）μm；TS-Ⅱ则分布于背面的翅脉上，数量为（5±1.41）根，长度为（57.25±21.84）μm，着生于有明显凹陷的基窝中。

前翅腹面边缘以及翅脉处还分布有钟形感器样结构，数量为（5.00±3.46）个；另外还发现一种锥形感器样结构，位于前翅腹面边缘，数量为（21.00±4.36）个，长（8.25±2.09）μm。

研究结果有助于从超微水平对白背飞虱翅的形态结构有个更深入的了解，进一步理解其迁飞扩散的能力，为寻找更好的防控措施打下基础。

关键词：白背飞虱Sogatella furcifera；长翅型；毛形感器样结构；钟形感器样结构；锥形感器样结构中图分类号：Q965 文献标志码：A 文章编号：2097 - 0137（2024）01 - 0066 - 05Ultrastructures of the wings fromthe long-winged female adult of Sogatella furciferaWU Jianer， LIANG Anwen， FENG Bo， HU Yang， WANG FanghaiSchool of Life Sciences， Sun Yat-sen University， Guangzhou 510275， ChinaAbstract：Sogatella furcifera is an important pest of rice. Long-winged adults can migrate over long distances and spread their harm. In this study， the ultramicroscopic characteristics of female adult plan‐thopper with long wings were studied by scanning electron microscopy. The results showed that： The middle of the fore and hind wing surface is thin and the edge is thick. The edge of the middle to the endof the wing has folded. There are many small spines evenly distributed on the back wing surface of the forewing， the length is（3.07± 0.48）μm， and there are many small spines on both sides of the hind wing. There were trichoid sensilla like apparatus on the dorsal surface and ventral surface of the fore‐wing， which could be divided into TS-I and TS-Ⅱ. TS-I distributed in the ventral wing base and perpen‐dicular to the ventral wing vein， and had no obvious basal fossa. The number of TS-I was 4±1.41， and the length was （31.80±2.43）μm. TS-Ⅱ was distributed on the dorsal vein of the wing， and the numberof TS-Ⅱ was 5±1.41， the length was （57.25±21.84）μm， and the TS-Ⅱ was located in the basal fossae with obvious depression. Campaniform sensilla like apparatuses were also distributed in the ventral edge of the forewing and in the veins， and the number was 5.00±3.46. In addition， a basiconic sensilla like apparatus with 21.00±4.36 in number and （8.25±2.09）μm in length was found on the ventral edgeDOI：10.13471/ki.acta.snus.2023E028*收稿日期：2023 − 05 − 10 录用日期：2023 − 10 − 25 网络首发日期：2023 − 12 − 05基金项目：广东省自然科学基金（2021A1515012402）；广州市科技计划项目（202002030019）作者简介：伍俭儿（1970年生），女；研究方向：动物形态与解剖学；E-mail：******************通信作者：王方海（1965年生），男；研究方向：昆虫生物化学与分子生物学；E-mail：****************第 1 期伍俭儿，等：长翅型白背飞虱雌成虫翅的超微特征of the forewing. The results of this study are helpful to further understand the morphological structure of the white back planthopper wing at the ultrastructural level ， and understand its ability to migrate and spread ， and lay a foundation for better prevention and control measures.Key words ： Sogatella furcifera ； long-winged ； trichoid sensilla like apparatus ； campaniform sensilla like apparatus ； basiconic sensilla like apparatus 白背飞虱Sogatella furcifera 是主要农作物水稻上的重要害虫，隶属于半翅目飞虱科（Zhou et al.， 2017）。

重酒石酸去甲肾上腺素Norepinephrine Bitartrate 英文药品说明书

Levophed™Norepinephrine BitartrateInjection, USP R x only DESCRIPTIONNorepinephrine (sometimes referred to as l-arterenol/Levarterenol or l-norepinephrine) is a sympathomimetic amine which differs from epinephrine by the absence of a methyl group on the nitrogen atom.Norepinephrine Bitartrate is (-)-α-(aminomethyl)-3,4-dihydroxybenzyl alcohol tartrate (1:1) (salt) monohydrate and has the following structural formula:LEVOPHED is supplied in sterile aqueous solution in the form of the bitartrate salt to be administered by intravenous infusion following dilution. Norepinephrine is sparingly soluble in water, very slightly soluble in alcohol and ether, and readily soluble in acids. Each mL contains the equivalent of 1 mg base of norepinephrine, sodium chloride for isotonicity, and not more than 2 mg of sodium metabisulfite as an antioxidant. It has a pH of 3 to 4.5. The air in the ampuls has been displaced by nitrogen gas.CLINICAL PHARMACOLOGYLEVOPHED functions as a peripheral vasoconstrictor (alpha-adrenergic action) and as an inotropic stimulator of the heart and dilator of coronary arteries (beta-adrenergic action).INDICATIONS AND USAGEFor blood pressure control in certain acute hypotensive states (e.g., pheochromocytomectomy, sympathectomy, poliomyelitis, spinal anesthesia, myocardial infarction, septicemia, blood transfusion, and drug reactions).As an adjunct in the treatment of cardiac arrest and profound hypotension. CONTRAINDICATIONSLEVOPHED should not be given to patients who are hypotensive from blood volume deficits except as an emergency measure to maintain coronary and cerebral artery perfusion until blood volume replacement therapy can be completed. If LEVOPHED is continuously administered to maintain blood pressure in the absence of blood volume replacement, the following may occur: severe peripheral and visceral vasoconstriction, decreased renal perfusion and urine output, poor systemic blood flow despite “normal” blood pressure, tissue hypoxia, and lactate acidosis.LEVOPHED should also not be given to patients with mesenteric or peripheral vascular thrombosis (because of the risk of increasing ischemia and extending the area of infarction) unless, in the opinion of the attending physician, the administration of LEVOPHED is necessary as a life-saving procedure.Cyclopropane and halothane anesthetics increase cardiac autonomic irritability and therefore seem to sensitize the myocardium to the action of intravenously administered epinephrine or norepinephrine.Hence, the use of LEVOPHED during cyclopropane and halothane anesthesia is generally considered contraindicated because of the risk of producing ventricular tachycardia or fibrillation.The same type of cardiac arrhythmias may result from the use of LEVOPHED in patients with profound hypoxia or hypercarbia.WARNINGSLEVOPHED should be used with extreme caution in patients receiving monoamine oxidase inhibitors (MAOI) or antidepressants of the triptyline or imipramine types, because severe, prolonged hypertension may result.LEVOPHED Bitartrate Injection contains sodium metabisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people. The overall prevalence of sulfite sensitivity in the general population is unknown. Sulfite sensitivity is seen more frequently in asthmatic than in nonasthmatic people. PRECAUTIONSGeneralAvoid Hypertension: Because of the potency of LEVOPHED and because of varying response to pressor substances, the possibility always exists that dangerously high blood pressure may be produced with overdoses of this pressor agent. It is desirable, therefore, to record the blood pressure every two minutes from the time administration is started until the desired blood pressure is obtained, then every five minutes if administration is to be continued.The rate of flow must be watched constantly, and the patient should never be left unattended while receiving LEVOPHED. Headache may be a symptom of hypertension due to overdosage.Site of Infusion: Whenever possible, infusions of LEVOPHED should be given into a large vein, particularly an antecubital vein because, when administered into this vein, the risk of necrosis of the overlying skin from prolonged vasoconstriction is apparently very slight. Some authors have indicated that the femoral vein is also an acceptable route of administration. A catheter tie-in technique should be avoided, if possible, since the obstruction to blood flow around the tubing may cause stasis and increased local concentration of the drug. Occlusive vascular diseases (for example, atherosclerosis, arteriosclerosis, diabetic endarteritis, Buerger’s disease) are more likely to occur in the lower than in the upper extremity. Therefore, one should avoid the veins of the leg in elderly patients or in those suffering from such disorders. Gangrene has been reported in a lower extremity when infusions of LEVOPHED were given in an ankle vein.Extravasation: The infusion site should be checked frequently for free flow. Care should be taken to avoid extravasation of LEVOPHED into the tissues, as local necrosis might ensue due to the vasoconstrictive action of the drug. Blanching along the course of the infused vein, sometimes without obvious extravasation, has been attributed to vasa vasorum constriction with increased permeability of the vein wall, permitting some leakage.This also may progress on rare occasions to superficial slough, particularly during infusion into leg veins in elderly patients or in those suffering from obliterative vascular disease. Hence, if blanching occurs, consideration should be given to the advisability of changing the infusion site at intervals to allow the effects of local vasoconstriction to subside.therefore seem to sensitize the myocardium to the action of intravenously administered epinephrine or norepinephrine. Hence, the use of LEVOPHED during cyclopropane and halothane anesthesia is generally considered contraindicated because of the risk of producing ventricular tachycardia or fibrillation. The same type of cardiac arrhythmias may result from the use of LEVOPHED in patients with profound hypoxia or hypercarbia.LEVOPHED should be used with extreme caution in patients receiving monoamine oxidase inhibitors (MAOI) or antidepressants of the triptyline or imipramine types, because severe, prolonged hypertension may result.Carcinogenesis, Mutagenesis, Impairment of Fertility: Studies have not been performed.Pregnancy Category C: Animal reproduction studies have not been conducted with LEVOPHED. It is also not known whether LEVOPHED can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. LEVOPHED should be given to a pregnant woman only if clearly needed.Nursing Mothers: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when LEVOPHED is administered to a nursing woman.Pediatric Use: Safety and effectiveness in pediatric patients has not been established.Geriatric Use: Clinical studies of LEVOPHED did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.LEVOPHED infusions should not be administered into the veins in the leg in elderly patients (see PRECAUTIONS, General).ADVERSE REACTIONSThe following reactions can occur:Body As A Whole: Ischemic injury due to potent vasoconstrictor action and tissue hypoxia. Cardiovascular System: Bradycardia, probably as a reflex result of a rise in blood pressure, arrhythmias. Nervous System: Anxiety, transient headache.Respiratory System: Respiratory difficulty.Skin and Appendages: Extravasation necrosis at injection site.Prolonged administration of any potent vasopressor may result in plasma volume depletion which should be continuously corrected by appropriate fluid and electrolyte replacement therapy. If plasma volumes are not corrected, hypotension may recur when LEVOPHED is discontinued, or blood pressure may be maintained at the risk of severe peripheral and visceral vasoconstriction (e.g., decreased renal perfusion) with diminution in blood flow and tissue perfusion with subsequent tissue hypoxia and lactic acidosis and possible ischemic injury. Gangrene of extremities has been rarely reported.Overdoses or conventional doses in hypersensitive persons (e.g., hyperthyroid patients) cause severe hypertension with violent headache, photophobia, stabbing retrosternal pain, pallor, intense sweating, and vomiting.OVERDOSAGEOverdosage with LEVOPHED may result in headache, severe hypertension, reflex bradycardia, marked increase in peripheral resistance, and decreased cardiac output. In case of accidental overdosage, as evidenced by excessive blood pressure elevation, discontinue LEVOPHED until the condition of the patient stabilizes.DOSAGE AND ADMINISTRATIONNorepinephrine Bitartrate Injection is a concentrated, potent drug which must be diluted in dextrose containing solutions prior to infusion. An infusion of LEVOPHED should be given into a large vein (see PRECAUTIONS).Restoration of Blood Pressure in Acute Hypotensive StatesBlood volume depletion should always be corrected as fully as possible before any vasopressor is administered. When, as an emergency measure, intraaortic pressures must be maintained to prevent cerebral or coronary artery ischemia, LEVOPHED can be administered before and concurrently with blood volume replacement.Diluent: LEVOPHED should be diluted in 5 percent dextrose injection or 5 percent dextrose and sodium chloride injections. These dextrose containing fluids are protection against significant loss of potency due to oxidation. Administration in saline solution alone is not recommended. Whole blood or plasma, if indicated to increase blood volume, should be administered separately (for example, by use of a Y-tube and individual containers if given simultaneously).Average Dosage: Add a 4 mL ampul (4 mg) of LEVOPHED to 1,000 mL of a 5 percent dextrose containing solution. Each mL of this dilution contains 4 mcg of the base of LEVOPHED. Give this solution by intravenous infusion. Insert a plastic intravenous catheter through a suitable bore needle well advanced centrally into the vein and securely fixed with adhesive tape, avoiding, if possible, a catheter tie-in technique as this promotes stasis. An IV drip chamber or other suitable metering device is essential to permit an accurate estimation of the rate of flow in drops per minute. After observing the response to an initial dose of 2 mL to 3 mL (from 8 mcg to 12 mcg of base) per minute, adjust the rate of flow to establish and maintain a low normal blood pressure (usually 80 mm Hg to 100 mm Hg systolic) sufficient to maintain the circulation to vital organs. In previously hypertensive patients, it is recommended that the blood pressure should be raised no higher than 40 mm Hg below the preexisting systolic pressure. The average maintenance dose ranges from 0.5 mL to 1 mL per minute (from 2 mcg to 4 mcg of base).High Dosage: Great individual variation occurs in the dose required to attain and maintain an adequate blood pressure. In all cases, dosage of LEVOPHED should be titrated according to the response of the patient. Occasionally much larger or even enormous daily doses (as high as 68 mg base or 17 ampuls) may be necessary if the patient remains hypotensive, but occult blood volume depletion should always be suspected and corrected when present. Central venous pressure monitoring is usually helpful in detecting and treating this situation.Fluid Intake: The degree of dilution depends on clinical fluid volume requirements. If large volumes of fluid (dextrose) are needed at a flow rate that would involve an excessive dose of the pressor agent per unit of time, a solution more dilute than 4 mcg per mL should be used. On the other hand, when large volumes of fluid are clinically undesirable, a concentration greater than 4 mcg per mL may be necessary.Duration of Therapy: The infusion should be continued until adequate blood pressure and tissue perfusion are maintained without therapy. Infusions of LEVOPHED should be reduced gradually, avoiding abrupt withdrawal. In some of the reported cases of vascular collapse due to acute myocardial infarction, treatment was required for up to six days.Adjunctive Treatment in Cardiac ArrestInfusions of LEVOPHED are usually administered intravenously during cardiac resuscitation to restore and maintain an adequate blood pressure after an effective heartbeat and ventilation have been established by other means. [LEVOPHED’s powerful beta-adrenergic stimulating action is also thought to increase the strength and effectiveness of systolic contractions once they occur.]Average Dosage: To maintain systemic blood pressure during the management of cardiac arrest, LEVOPHED is used in the same manner as described under Restoration of Blood Pressure in Acute Hypotensive States.Parenteral drug products should be inspected visually for particulate matter and discoloration prior to use, whenever solution and container permit.Do not use the solution if its color is pinkish or darker than slightly yellow or if it contains a precipitate.Avoid contact with iron salts, alkalis, or oxidizing agents.HOW SUPPLIEDLEVOPHED, norepinephrine bitartrate injection, USP, contains the equivalent of 4 mg base of LEVOPHED per each 4 mL ampul (1 mg/mL).Supplied as:Ampuls of 4 mL in boxes of 10, NDC 0409-1443-04Store at 20 to 25°C (68 to 77°F). [See USP Controlled Room Temperature.] Protect from light. Regitine, trademark, CIBA Pharmaceuticals Company.Revised: November, 2009Printed in USA EN-2297Hospira, Inc., Lake Forest, IL 60045, USA。

英语医学考试题目及答案

英语医学考试题目及答案一、选择题（每题2分，共20分）1. Which of the following is a common symptom of the common cold?A. FeverB. CoughC. Sore throatD. All of the above答案：D2. The primary function of the heart is to:A. Oxygenate the bloodB. Filter the bloodC. Circulate the blood throughout the bodyD. Store the blood答案：C3. What is the medical term for inflammation of the stomach lining?A. GastritisB. GastroenteritisC. ColitisD. Hepatitis答案：A4. The hormone responsible for the regulation of blood sugar levels is:A. InsulinB. ThyroxineC. CortisolD. Adrenaline答案：A5. Which of the following is a type of cancer that affects the blood and bone marrow?A. LeukemiaB. MelanomaC. LymphomaD. Carcinoma答案：A6. The process of cell division is known as:A. MitosisB. MeiosisC. ApoptosisD. Cytokinesis答案：A7. What is the correct term for the study of the structure of the body?A. AnatomyB. PhysiologyC. PathologyD. Pharmacology答案：A8. The respiratory system is responsible for the exchange of:A. Oxygen and carbon dioxideB. Nutrients and wasteC. Water and electrolytesD. Hormones and neurotransmitters答案：A9. Which organ is responsible for detoxification of the body?A. LiverB. KidneyC. LungsD. Spleen答案：A10. The nervous system is divided into two main parts: the central nervous system and the:A. Peripheral nervous systemB. Autonomic nervous systemC. Somatic nervous systemD. Sympathetic nervous system答案：A二、填空题（每空1分，共10分）11. The largest organ of the human body is the _______.答案：Skin12. The medical condition characterized by high levels of glucose in the blood is known as _______.答案：Diabetes13. The process by which the body breaks down food into nutrients is called _______.答案：Digestion14. The study of the causes and effects of diseases is known as _______.答案：Etiology15. A person with a medical condition that causes difficulty in breathing is said to have _______.答案：Asthma16. The main function of the kidneys is to _______.答案：Filter waste products from the blood17. The branch of medicine that deals with the diagnosis and treatment of mental disorders is called _______.答案：Psychiatry18. The medical term for the surgical removal of a tumor is _______.答案：Excision19. The study of the causes and development of diseases is known as _______.答案：Pathology20. The process by which the body maintains a stable internal environment is called _______.答案：Homeostasis三、简答题（每题5分，共20分）21. Explain the difference between a virus and a bacteria.答案：Viruses are smaller and require a host cell to replicate, while bacteria are larger, single-celled organisms that can reproduce independently. Viruses cause infections by invading host cells and using the host's machinery to replicate, whereas bacteria can cause infections by multiplying on their own.22. What is the role of white blood cells in the immune system?答案：White blood cells, also known as leukocytes, play a crucial role in the immune system by identifying and eliminating pathogens such as bacteria, viruses, and other foreign substances. They help in the body's defense mechanism through various processes like phagocytosis, producing antibodies, and cell-mediated immunity.23. Describe the process of blood clotting.答案：Blood clotting, or coagulation, is a complex process that prevents excessive bleeding when a blood vessel is injured. It involves a series of reactions where clottingfactors in the blood are activated in a cascade, leading to the formation of a fibrin mesh that traps blood cells and forms a clot. This process also includes the activation of platelets which aggregate at the site of injury to form a plug.24. What are the functions of the liver?答案：The liver performs a multitude of。

对于顽固性带状疱疹后神经痛患者是否可行脊神经根射频毁损治疗

中华疼痛学杂志2021 年4月第 17卷第2期Chin J Painol. April 2021. Vol.17. IN〇.2133•读者来信•对于顽固性带状疱疹后神经痛患者是否可行脊神经根射频毁损治疗？黄冰’林慧丹21嘉兴学院附属医院疼痛科，浙江省嘉兴市314000;:宁波市第一医院疼痛科315000通信作者：黄冰，Email:jxhl>999@【摘要]带状疱疹后神经痛是典型的神经病理性疼痛，也是公认的难治性疼痛之一。

在没有更好的治疗办法之前，对责任神经根进行选择性射频热凝毁损仍是较为有效的方法，但应避免毁损支配四肢的有显性运动功能的脊神经。

【关键词】神经痛，带状疱疹后；射频热凝术；脊神经根D0I:丨 0.3760/ 101658-20210320-00053Is radiofrequency ablation of spinal nerve root available for the patients with intractable postherpeticneuralgia?Huang Bing1, Lin Huidan2'Department of Pain Medicine, the Affiliated Hospital of Jinxing University, Jiaxing City, Zhejiang Province314000, China; 2Department of Pain Medicine, the First Hospital of Ningbo, Ningbo City, Zhejiang Province315000, ChinaCorresponding author: Huang Bing, Email: ****************【A bstract】Postherpetic neuralgia is a typical neuropathic pain, and it is also recognized as one of theintractable pain. Until now, selective radiofrequency thermocoagulation of responsible nerve roots is still themost effective method, but it should be avoided to damage the spinal nerves with dominant motor functions thatinnervate the limbs.【K e y w o rd s】Neuralgia, postherpetic; Radiofrequency thermocoagulation; Spinal nerve root1)01: 10.3760/ 101658-20210320-00053《中华疼痛学杂志》2020年第6期上的《C T引导下颈脊神经根射频热凝术治疗颈枕部顽固性带状疱疹后神经痛的效果》一文发表后，我国疼痛界元老级资深专家莫世湟和王家双两教授同时提出质疑，对此，我们深感惶恐。

Observations on flattened species of Gracilaria (Gracilariaceae, Rhodophyta)

Journal of Applied Phycology(2006)18:671–678DOI:10.1007/s10811-006-9072-4C Springer2006 Observations onﬂattened species of Gracilaria(Gracilariaceae,Rhodophyta) from TaiwanShowe-Mei LinDepartment of Natural Science Education,National Taitung University,Taitung950,Taiwane-mail:smlin@.twKey words:taxonomy,Taiwan,Rhodophyta,Gracilariaceae,Gracilaria punctata,G.vieillardii,G.spinulosa, HydropuntiaAbstractFourﬂattened Gracilaria species have been reported from Taiwan:G.spinulosa,G.vieillardii,G.textorii and G.punctata,identiﬁed based on branching pattern,the presence or absence of spines,and characters that often vary seasonally.Gracilaria spinulosa was originally described from the type locality,Tainan.Species with toothed margins are usually referred to G.“vieillardii”;those with smooth margins to G.“textorii”,and those with smooth margins and dark spots scattered over the blade to G.“punctata”.Molecular analyses show that specimens with marginal teeth cluster in three different groups:a G.“vieillardii”clade,a G.spinulosa clade,and a clade sister to G.spinulosa.An undescribed species comprises the third clade,which is distinguished by its relatively large gonimoblast cells and weakly developed tubular nutritive cells.The three clades can be separated by the character of the tubular nutritive cells,the size of gonimoblast cells and certain vegetative features.Plants with entire margins form a single clade characterized by cystocarps with basal tubular nutritive cells and their absence in the cystocarp cavity.They are nested in the Hydropuntia complex and are referred to as Gracilaria“punctata”here.The records of G.textorii and G.punctata from Taiwan require reinvestigation in comparison with the Japanese species.IntroductionSpecies in the red algal genus Gracilaria(C.Agardh) Greville1830in the family Gracilariaceae include some economically important agarophytes.Histori-cally,there were eighteen species recorded from Tai-wan(Chiang,1985;Lewis&Norris,1987;Huang, 1999);among them,fourﬂattened species,G.spinu-losa(Okamura)Chang et Xia1976,G.vieillardii Silva in Silva,Me˜n ez et Moe1987,G.textorii(Suringar) De Toni1895,and G.punctata(Okamura)Yamada 1941.These were identiﬁed based on branching pat-tern and the presence or absence of marginal spines.G. spinulosa was originally described from Tainan,Tai-wan,based on Rhodymenia spinulosa Okamura1934. Species with toothed margins were usually referred to G.“vieillardii”(Chiang,1985),those with smooth margins to G.“textorii”(Huang,1999),and those with smooth margins and dark spots scattered over the blade to G.“punctata”(Yamada,1941;Ohmi,1958). Recent collections around the coasts of Taiwan have permitted a new interpretation of the Taiwan species. In this study,the vegetative and reproductive morphol-ogy of the fourﬂattened species are described in detail and their taxonomic status is discussed based on rbc L sequence analyses.Material and methodsCollections were made either by SCUBA or snorkel. Treatment of the algal samples,sectioning and stain-ing techniques used in the morphological studies,DNA sequencing procedures and phylogenetic analyses are as described in Lin et al.(2004).V oucher specimens are deposited in the Herbarium of the National Taitung University,Taiwan.Collection information and new rbc L sequences generated in this study and those avail-able from GenBank are shown in Table1.[445]672Table1.List of species used in rbc L analysis and accession numbers in GenBank.The number after the accession number is the percentage of the gene sequencedSpecies Collection information/GenBank accession numberGracilaria“punctata”Sail Rock,Kenting National Park,southern Taiwan,coll.S.M.Lin,1.×.2002.AY737447,98%Gracilaria“punctata”Lungkeng,Kenting National Park,southern Taiwan,coll.S.M.Lin,2.iv.2001.AY737446,96.1%Gracilaria“punctata”Five Caves,Orchid Island,Taiwan,coll.S.M.Lin,17.iv.2003.AY737448,98.4%Gracilaria“vieillardii”Houwan,Kenting National Park,southern Taiwan,coll.S.M.Lin,24×.2001.AY737436,99.5%Gracilaria“vieillardii”Five Caves,Orchid Island,coll.S.M.Lin,17.iv.2002.AY737437,98.3% Gracilaria beckeri(J.Agardh)Papenfuss AY049377∗,96.3%Gracilaria bursa-pastoris(Gmelin)Silva AY049376∗,91.6%Gracilaria capensis Schmitz ex Mazza AY049378∗,96.5%Gracilariaﬂabelliforme(P.et H.Crouan)Fredericq et Gurgel AY049343∗,98.8%Gracilaria hayi Gurgel,Fredericq et J.N.Norris AY049319∗,95.6%Gracilaria multipartite(Clement)Harvey AY049322∗,98.6%Gracilaria occidentalis(Børgesen)Bodard AY049322∗,98.6%Gracilaria smithsoniensis Gurgel,Fredericq et J.N.Norris AY049321∗,97.3%Gracilaria sp.Yeliu,northern Taiwan,coll.Allen Liu,26.vii.2002.AY737438,98.1% Gracilaria sp.Sail Rock,Kenting National Park,southern Taiwan,coll.S.M.Lin,14.iii.2002.AY737439,96.8%Gracilaria sp.Keelung,northern Taiwan,coll.S.M.Lin,1.v.2002.AY737440,98.1% Gracilaria spinulosa Wind Blow Sand,Kenting National Park,southern Taiwan,coll.S.M.Lin,21.vii.2001.AY737441,95.7%Gracilaria spinulosa Ya Din,Tainan,western Taiwan,coll.D.T.Lin,26.v.2003.AY737442,98.3%Gracilaria spinulosa Lin Ping,Pingtung County,southwest Taiwan,coll.Y.S.Huang,10.ii.2002.AY737443,98.4%Gracilaria spinulosa Little Yeliu,Taitung,eastern Taiwan,coll.S.M.Lin&F.K.Huang,18.iii.2003.AY737444,98.3%Gracilaria textorii(Suringar)De Toni AY049325∗,97.5%Gracilaria venezuelensis Taylor AF539603∗,95.4%Gracilaria vieillardii Bulusan,N.Philippines,coll.Allen Liu,18.ii2003.AY737445,98.4% Gracilaria yoneshigueana Gurgel,Fredericq et J.N.Norris AY049372∗,93.4%Gracilariopsis bailiniae Zhang et Xia AY049411∗regarded as Gracilariopsis heteroclada91.1% Gracilariopsis lemaneiformis(Bory de Saint-Vincent)E.Y.AY049415∗,97.6%Dawson,Acleto et FoldvikHydropuntia caudata(J.Agardh)Gurgel et Fredericq AY049358∗,76.4%Hydropuntia corne a(J.Agardh)Wynne AY049338∗,98.8%Hydropuntia crassissima(P.et H.Crouan)Wynne AY049351∗,98%Hydropuntia eucheumatoides(Harvey)Gurgel et Fredericq AY049389∗,93.3%Hydropuntia urvillei Montagne AY049402∗,97.4%Hydropuntia usneoides(C.Agardh)Gurgel et Fredericq AY049346∗,98%∗Refers to Gurgel and Fredericq(2004).[446]673 Figure1–10.(1–6)Gracilaria spinulosa(Figures1and6,Tainan,southwestern Taiwan,Figures2–5,Sail Rock).(1)A typical cystocarpic specimen showing dense branches in upper parts of the thallus.(2)A typical male plant showing loose branches with more or less entire margins.(3)Cross-section of spermatangial conceptacles.(4)Cross-section of vegetative thallus.(5)Transverse section of a young,multinucleate fusion cell(arrowhead)and the supporting cell(arrow).(6)Transverse section of a mature cystocarp showing the gonimoblasts and some tubular nutritive cells(arrows)arisen from the upper parts of gonimoblasts.Gracilaria“vieillardii”(Kenting National Park,southern Taiwan:(7),Sail Rock,(8–10),Houwan)(7)Female specimens with marginal spines.(8)Female plant with marginal lobes.(9)Cross-section through a vegetative thallus.(10)Transverse section of a mature cystocarp showing the gonimoblasts and some tubular nutritive cells penetrating the cystocarpﬂoor.ResultsObservationsGracilaria spinulosa(Okamura)Chang et Xia1976, 11:148,Figure42.(Figures1–6).Synonym:Rhodymenia spinulosa Okamura1934,7(4): 33,pl.318,Figures1–6.Distribution in Taiwan:This alga is distributed in east-ern(Taitung)and southwestern(Tainan,type local-ity)to southern(Kenting)Taiwan.Habitat and seasonality:Plants grew all year round and were attached to rocky coral reefs or man-made concrete substrata in intertidal to subtidal zones,0–2m deep,sometimes in association withG.“vieillardii”.[447]674Specimens examined:Kenting National Park,south-ern Taiwan:(1)Sail Rock,coll.Allen Liu,26.i.2004, tetrasporic and male;coll.S.-M.Lin,28.xi.2001, 17.i.2002,27.iii.2004,male,female and tetrasporic;(2)Houwan,coll.S.-M.Lin,18.xii.2001,vegeta-tive;(3)Lungkeng,S.-M.Lin,19.vii.2001,03.x.2001, tetrasporic.Tainan,southwestern Taiwan:coll.D.-T. Lin,16.vii.2003,female.Taitung,eastern Taiwan:coll. S.-M.Lin&F.-K.Huang,8.iii.2003,vegetative.Thalli are bushy and erect,2.8–9cm long,consisting of loose to dense,irregularly dichotomously branched,ﬂattened blades,2–7mm wide,arising from a discoid holdfast,2–3mm in diameter,occasionally with a short stipe1–2.5mm long(Figures1,2).The margins of blades are toothed(Figure1)or rarely entire(Figure2). Blades are110–160(-405)µm in thickness,composed of1–2layers of pigmented cortical cells,5–8µm long by5–6µm wide,1–2layers of sub-cortical cells,30–65µm in diameter,and2–3layers of medullary cells, 75–90(−120)µm high by90–120(−195)µm wide (Figure4).Blades are rose red to dark red,occasionally greenish in colour.Reproductive structures are scat-tered over both sides of blades.Spermatangia are scat-tered over the surface of male gametophytes in shallow, textorii-type conceptacles(Figure3).Tetrasporangia are cruciate,scattered over the surface of the thallus ex-cept the basal part.Cystocarps are hemispherical and slightly constricted at the base,1.1–1.4mm in diameter (Figure6),scattered over the mid to upper part of the thallus.Gonimoblast initials(not shown)are cut off from the multinucleate fusion cell(Figure5).Tubu-lar nutritive cells are present in the cystocarp cavity and in theﬂoor of the cystocarp and inner gonimoblast cells are55–28µm long by25–35µm wide.Carpospo-rangia are uninucleate,borne in branched chains,15–20µm wide by15–23µm long.Gracilaria“vieillardii”Silva in Silva,Me˜n ez et Moe 1987:44(Figures7–10)Distribution:Eastern(Taitung,Green Island,Orchid Island)to southern(Kenting)Taiwan.Habitat and seasonality:Plants grew from early winter (October)to spring(April)and were attached inter-tidally to rocky coral reefs in tide pools,usually in association with G.spinulosa.Specimens examined:Kenting National Park,south-ern Taiwan:1)Sail Rock,coll.Allen Liu,26.i.2004, female;coll.S.-M.Lin,27.iii.2004,vegetative;2) Houwan,coll.S.-M.Lin,18.xii.2001,female.Eastern Taiwan:1)Taitung,coll.F.-K.Huang,12.i.2002,veg-etative;2)Orchid Island,coll.S.-M.Lin,17.iv.2002, vegetative.Thalli are slightly prostrate or erect,2.5–6cm long and consist of irregularly dichotomously branched,ﬂattened blades,3–12mm wide,arising from a conspicuous,discoid holdfast,3–11mm in diameter, occasionally with a short stipe1–4mm long(Figures7, 8).The margins of young blades are mostly entire (Figure8);when old,upper parts of blades possessﬁne marginal spines(Figure7).Blades are255–395µm in thickness,composed of2layers of pigmented cor-tical cells,6–7µm in diameter,2–3layers of sub-cortical cells,15–35µm in diameter,and a3-layered medulla composed of cells,30–55µm high by50–125µm wide(Figure9).Blades are bright to dark red when shaded or greenish in color when exposed to sun-light.Spermatangial and tetrasporic plants were not observed.Cystocarps are scattered over both sides of blades and are hemispherical and slightly constricted at the base,1.5–1.9mm in diameter(Figure10).Tubu-lar nutritive cells are mostly restricted to the base of the carposporophyte and the inner gonimoblast cells are interconnected to form a network(Figure10).Car-posporangia are uninucleate,borne in branched chains, 12–15µm wide by15–20µm long.Gracilaria sp.(Figures11–16)Habitat and seasonality: Plants were found in tide pools or grew subtidally, 1–2m deep,and seasonally from early winter to late summer(November-August).Specimens examined:Kenting National Park,south-ern Taiwan:1)Sail Rock,coll.Allen Liu,26.i.2004, tetrasporic and male;coll.S.-M.Lin,14.iii.2002,27.iii.2004,female and tetrasporic;2)Houwan,coll.S.-M.Lin,13.xii.2001,vegetative;3)Ba-nana Bay,S.-M.Lin,29.iii.2002,tetrasporic.North-ern Taiwan:1)Yeliu,coll.Allen Liu,27.vii.2002, female;2)Keelung,coll.S.-M.Lin, 1.v.2002, vegetative.Thalli are erect,4–8cm long,and consist of irreg-ularly dichotomously branched,ﬂattened blades,5–13mm wide,arising from a stipe,5–18mm long,witha discoid holdfast,2–4mm in diameter(Figures11,12).The blades are associated with marginal spines or lobes(Figure11),and also have numerous,tiny lobes or bladelets,1–3mm long by1–4mm wide aris-ing from their surfaces(Figure12).Blades are250–500µm thick,composed of1–2layers of pigmented cortical cells,5–6µm in diameter,1–2layers of sub-cortical cells,12–20µm in diameter,and one layer of medullary cells,75–100µm high by150–200µm wide(Figure13).Blades are rose to dark red,occa-sionally greenish in colour.Reproductive structures are scattered over both sides of blades.Spermatangia are[448]675 Figure11–25.Gracilaria sp.(Sail Rock,Kenting National Park,southern Taiwan)(11)Female thallus.(12)Fresh plant showing numerous bladelets(arrowheads)born on the thallus surface.(13)Cross-section of vegetative thallus.(14)Cross-section of male gametophyte showing shallow textorii-type spermatangial conceptacles.(15)Cross-section of tetrasporophyte showing a mature tetrasporangium(arrow)and some young ones.(16)Transverse section of a mature cystocarp showing the gonimoblasts and the remaining fusion cell(arrow).Gracilaria“punctata”((17)Taitung,eastern Taiwan,(18–25),Sail Rock)(17)Cystocarpic plant.(18)Cross-section of vegetative thallus.(19)Transverse section of immature tetrasporangia.(20)Transverse section of immature spermatangial conceptacles.(21)Transverse section of mature,P olycavernosa-type spermatangial conceptacles.(22)Transverse section of a very young cystocarp showing the pre-existing cavity.(23)Transverse section of mature cystocarp showing the gonimoblasts and basal tubular nutritive cells.(24)Same section as in(23)showing close up of basal tubular nutritive cells.(25)Close up of uninucleate carposporangia in unbranched chains.scattered over the surface of male gametophytes in shal-low,textorii-type conceptacles(Figure14).Tetraspo-rangia are superﬁcial and cruciately divided(Figure 15).Cystocarps are hemispherical and slightly con-stricted at the base,1.6–2.2mm in diameter with the inner gonimoblast cells75–115µm long by40–60µm wide(Figure16).Tubular nutritive cells are seldom found in mature cystocarps,and carposporangia are uninucleate,18–25µm wide by20–33µm long and borne in branched chains.Gracilaria“punctata”(Okamura)Yamada1941: 203(Figures17–25)Synonym:Rhodymenia punctata Okamura1929: 13,pl.258,Figures1—6.Distribution:Eastern(Taitung)to southern (Kenting)Taiwan.Habitat and seasonality:Plants grew seasonally from winter(December)to summer in tide pools,or subtidally in sandy substrata or on rocky coral reef, 1–2m deep.[449]676Specimens examined:Kenting National Park,south-ern Taiwan:1)Sail Rock,coll.Allen Liu,26.i.2004, tetrasporic,female and male;coll.S.-M.Lin,10.i.2002, 14.iii.2002,27.iii.2004,male,female and tetrasporic;2)Lungkeng,coll.S.-M.Lin,2.iv.2001,22.vii.2001, tetrasporic.Eastern Taiwan:1)Taitung coll. F.-K. Huang,12.i.2002,female;2)Orchid Island,coll.S.-M.Lin,17.iv.2002,vegetative.Thalli are erect,4.5–8.7cm high,consisting of ir-regularly to pseudodichotomously branched blades, 7–28mm wide,arising from a discoid holdfast,2.5–5mm in diameter(Figure17),usually with a stipe 5–15mm long.The margins of blades are wavy,ruf-ﬂed or entire and the surfaces of blades contain scat-tered brown to dark red spots,sometimes with colorless hairs,15–40µm long.Blades are260–560µm thick, composed of1–2layers of pigmented cortical cells, 6–8µm long by5–7µm wide,1–2layers of subcor-tical cells,12–30µm in diameter,and1-2-3layer of medullary cells,40–140µm high by80–210µm wide (Figure18).Blades are rose red to dark red.Reproduc-tive structures are scattered over both sides of blades. Tetrasporocytes are scattered over the thallus surface embedded in nemathecia,surrounded by elongated cor-tical cells(Figure19).Mature tetrasporangia were not found in any of the tetrasporic plants examined.Sper-matangial conceptacles are scattered over the thallus surface and are cup shaped when young(Figure20), but become conﬂuent as in the Polycavernosa-type con-ceptacle at maturity(Figure21).Cystocarps are hemi-spherical,constricted at the base,1.5–2.1mm in diam-eter(Figure23),scattered over the thallus.The cav-ity of the cystocarp is formed before the gonimoblast initials are cut off from the multinucleate fusion cell (Figure22).Tubular nutritive cells are absent in the cys-tocarp cavity(Figure23)and are restricted to the base of the carposporophyte where they penetrate theﬂoor of the cystocarp(Figure24).Carposporangia are un-inucleate,15–20µm wide by20–28µm long,and are borne in straight chains(Figure25).Molecular analysisThe rbc L sequences of G.spinulosa,G.“vieillardii”, Gracilaria sp.,Gracilaria“punctata”from Taiwan and G.vieillardii from the Philippines were newly gen-erated,and a set of17additional representative taxa belonging to the genera Gracilaria and Hydropuntia were selected for analysis,together with two species of Gracilariopsis which served as the outgroup(see Table1,Figure26).Theﬁnal rbc L data matrix was re-stricted to1407sites.Parsimony analysis revealed two most parsimonious trees with tree length of925steps, CI=0.5459and RI=0.7077;there were303informa-tive characters out of1407included sites(22%).Boot-strap proportion values(1000replicates)and decay in-dices derived from maximum parsimony analysis are shown on the nodes.Branch lengths are proportional to the amount of sequence change.Theﬂattened species of Gracilaria from Taiwan formed four separate clades based on rbc L sequence analyses:three in the Gracilaria complex and one in the Hydropuntia complex(Figure26).Interspeciﬁc rbc L sequence divergences among species of the Gracilaria complex varied from1.2to8.2%,whereas they dif-fered from1.1%to10.7%in the Hydropuntia complex. The specimens with marginal teeth clustered in three different groups in the Gracilaria complex:a G.“vieil-lardii”clade,a G.spinulosa clade,and a clade sister to G.vieillardii from the Philippines.G.“vieillardii”showed a close relationship to the G.beckeri/G.capen-sis clade from South Africa,whereas the position of G.spinulosa was unresolved between G.“vieillardii”with3.6%sequence divergence(41characters)and the Gracilaria sp.clade with4.2%sequence divergence (51characters).The taxa from the Hydropuntia com-plex formed two paraphyletic clades:one containing the type,H.urvillei and one containing G.“punctata”from Taiwan along with some other Caribbean species. DiscussionThe phylogenetic relationships among the species of the family Gracilariaceae have been extensively stud-ied using DNA sequencing in recent years(Bird et al., 1994;Bellorin et al.,2002;Gurgel&Fredericq,2004). Liao and Hommersand(2003)recently examined the types of genera that have been proposed historically for the species of Gracilaria and recognized nine types, based mainly on the formation of spermatangial con-ceptacles and cystocarp development.They provided a description of each type and assigned species presently placed in Gracilaria to each of the groups.Gurgel and Fredericq(2004)identiﬁed nine distinct evolutionary lineages in Gracilaria sensu lato based on rbc L se-quence analyses and classiﬁed the species into two genera:Gracilaria sensu stricto and Hydropuntia,em-phasizing both the manner of formation of the sper-matangial conceptacles and the cystocarp features.[450]677 Figure26.One of two most parsimonious trees from analysis of the rbc L sequence data.Bootstrap proportion values are shown above nodes and thick bold branches correspond to100%support;decay indices are shown below nodes.Branch lengths are proportional to the amount of sequence change.Molecular analyses in this study showed that the fourﬂattened species of Gracilaria from Taiwan fall into four distinct clades:three(G.spinulosa,G.“vieil-lardii”,Gracilaria sp.)in Gracilaria sensu stricto and one(G.“punctata”)in Hydropuntia,as circumscribed by Gurgel and Fredericq(2004)(see Figure26).Al-though G.spinulosa,G.“vieillardii”and Gracilaria sp.formed three distinct clades,they are closely related to G.vieillardii from the Philippines and G.beckeri and G.capensis from South Africa.All of these species con-sistently formed a single clade sister to G.textorii from Japan in the analyses,although with a low bootstrap support.Gracilaria sp.is an undescribed species char-acterized by a thallus surface bearing numerous lobes or bladelets(see Figures11and12),by relatively large inner gonimoblast cells,and by a lack tubular nutri-tive cells in the cavity of cystocarp compared to G. spinulosa.This species will be published in a separate paper.Gracilaria“vieillardii”and G.spinulosa are morphologically similar to each other,but the former can be separated from the latter by its slightly pros-trate habit,smaller and less branched thallus,relatively wider blades,and tubular nutritive cells that are mainly restricted to theﬂoor of the cystocarp.Gracilaria vieil-lardii has been widely used as a name for theﬂattened species with marginal spines throughout the Western Paciﬁc Ocean(Yamamoto,1978;Chiang,1985;With-ell et al.,1994).Gracilaria“vieillardii”from Taiwan remains provisional because of the absence of a detailed description of G.vieillardii from the type locality,New Caledonia.Okamura(1929)described a new species,Rhody-menia punctata,from Tosa,Japan in the absence of information about female reproductive structures.Ya-mada(1941)examined some female and tetrasporic specimens of a Gracilaria species collected from Tairi and Garanbi,Taiwan,and compared them with the type specimen of R.punctata.He came to the conclusion that the Taiwan species was the same as R.punctata and transferred the species to Gracilaria,as G.punc-tata(Okamura)Yamada without,however,providing any description orﬁgures of the internal structure of the cystocarp.Ohmi(1958)reported that tubular nutritive cells were present and linked the outer gonimoblast cells to the outer pericarp and that the spermatangia were in shallow,solitary or conﬂuent conceptacles in[451]678G.punctata.Ohmi’s observations were based on ma-terial collected in ter,Yamamoto(1978) investigated material from Komesu,Okinawa Prefec-ture,Japan and reported that the tubular nutritive cells were few in number in the cystocarp cavity and that the tetrasporangia were embedded in a slightly raised nemathecium surrounded by elongated cortical cells. Gracilaria“punctata”from Taiwan differs from Ya-mamoto’s(1978)description only in the absence of tubular nutritive cells in the cavity.The material of Gracilaria punctata from Taiwan examined by Ohmi (1958)may be related to Gracilaria sp.examined in this study.None of theﬂattened species of Gracilaria from Taiwan sequenced in this study matches G.tex-torii from Japan(See Figure26).This suggests that the records of G.textorii and G.punctata from Taiwan re-quire reinvestigation and comparison with the Japanese species.AcknowledgementsThis study was mainly supported by National Sci-ence Council research grants92-2621-B-143-001and 92-3114-B-143-001to SML.SML thanks her collect-ing partners F.-K.Huang and Allen Liu for assisting withﬁeldwork and D.-T.Lin for sending the material of G.spinulosa from Tainan.Dr.F.Gurgel provided the additional rbc L sequences of the Gracilariaceae is highly acknowledged.Special thanks go to Dr.Max H.Hommersand for his critical comments and sugges-tions,which have improved the quality of this article. ReferencesBellorin AM,Oliveira MC,Oliveira EC(2002)Phylogeny and sys-tematics of the marine algal family Gracilariaceae(Gracilariales, Rhodophyta)based on small subunit rDNA and ITS sequences of Atlantic and Paciﬁc species.Journal of Phycology38:551–563.Bird CJ,Ragan MA,Critchley AT,Rice EL,Gutell RR(1994) Molecular relationships among the Gracilariaceae(Rhodophyta): Further observations on some undetermined species.European Journal of Phycology29:195–202.Chang CF,Xia BM(1976)Studies on Chinese species of Gracilaria.Studia Marina Sinica11:91–163.Chiang Y-M(1985)Gracilaria from Taiwan:key,list and distribu-tion of the species.In Abbott IA,Norris JN(eds),Taxonomy of Economic Seaweeds with References to Some Paciﬁc and Caribbean Species,California Sea Grant College Program,La Jolla,CA,81–83.De Toni GB(1895)Phyceae japonicae novae addita enumeratione al-garum in ditione maritima Japoniae hucusque collectarum.Mem-orie del Reale Istituto Veneto di Scienze,Lettere ed Arti25:1–78. Greville RK(1830)Algae Britannicae....Maclachlan&Stewart, Edinburgh.Gurgel CFD,Fredericq S(2004)Systematics of the Gracilariaceae (Gracilariales,Rhodophyta):A critical assessment based on rbc L sequence analysis.Journal of Phycology40:138–159.Huang S-F(1999)Floristic studies on the benthic marine algae of northeastern Taiwan.Taiwania44:217–298.Lewis JE,Norris JN(1987)A History and Annotated Account of the Benthic Marine Algae of Taiwan,Smithsonian Institution Press, Washington,D.C.Liao LM,Hommersand MH(2003)A morphological study and tax-onomic reassessment of the generitype species in the Gracilari-aceae.Journal of Phycology39:1207–1232.Lin S-M,Hommersand MH,Fredericq S(2004)Two new species of Martensia(Delesseriaceae,Rhodophyta)from Kenting National Park,southern Taiwan.Phycologia43:13–25.Ohmi H(1958)The species of Gracilaria and Gracilariopsis from Japan and adjacent waters.Memoirs of the Faculty of Fisheries, Hokkaido University6:1–66.Okamura K(1929)Icones of Japanese algae.V ol.VI,Tokyo. Okamura K(1934)Icones of Japanese algae.V ol.VII,Tokyo. Silva PC,Me˜n ez EG,Moe RL(1987)Catalog of the benthic marine algae of the Philippines.Smithsonian Contributions to Marine Sciences27:1–179.Yamada Y(1941)Notes on some Japanese algae IX.Scientiﬁc Pa-pers of the Institute of Algological Research,Hokkaido Imperial University2:195–215.Yamamoto H(1978)Systematic and anatomical study of the genus Gracilaria in Japan.Memoirs of the Faculty of Fisheries, Hokkaido University25:97–152.Withell AF,Millar AJK,Kraft GT(1994)Taxonomic studies of the genus Gracilaria(Gracilariales,Rhodophyta)from Australia.Australian Systematic Botany7:281–352.[452]。

UTILIZATION OF INTERFERON ALPHA 5 IN THE TREATMENT

专利名称：UTILIZATION OF INTERFERON ALPHA 5 INTHE TREATMENT OF VIRALHEPATOPATHIES发明人：PRIETO VALTUENA, Jesús,CIVEIRA MURILLO,M Pilar,LARREA LEOZ, Esther申请号：EP99919282.6申请日：19990513公开号：EP1077068A1公开日：20010221专利内容由知识产权出版社提供专利附图：摘要：The invention relates to the use of interferon alpha 5 in the treatment of viralhepatopathies. The invention describes the reduced synthesis of IFNα5 in the livers of patients with hepatitis C in comparison to healthy livers. The sub-type of IFN expressed in said healthy livers corresponded only to the subtype alpha 5 in comparison with the different sub-types expressed in ill livers. The sequence SEQ ID NO:1 shows the partial sequence of cDNA corresponding to IFNα5. These significant differences between the expression patterns of some livers an others demonstrate the importance of the use of such interferon sub-type in the fabrication of compositions useful in the treatment of viral hepatopathies. The invention discloses in details such utilization in different forms and processes, including those which use the production of recombinant proteins from sequences of the type SEQ ID NO:1.申请人：INSTITUTO CIENTIFICO Y TECNOLOGICO DE NAVARRA, S.A.地址：Avda. de Pio XII, 53 31008 Pamplona ES国籍：ES代理机构：Elzaburu, Alberto de更多信息请下载全文后查看。

阿达木单抗治疗类风湿关节炎的疗效和安全性

论著DOI：10.16662/ki.1674-0742.2023.04.029阿达木单抗治疗类风湿关节炎的疗效和安全性刘睿，宋冬云，崔璨徐州矿务集团总医院风湿科，江苏徐州221004［摘要］目的探讨阿达木单抗在类风湿关节炎（rheumatoid arthritis, RA）治疗中的临床效果及安全性。

方法选取2018年5月—2022年4月徐州矿务集团总医院收治的RA患者48例为研究对象，以随机数表法分为对照组（24例，予以甲氨蝶呤治疗）、观察组（24例，基于对照组予以阿达木单抗治疗）。

对比两组治疗效果、血清水平、关节压痛与肿胀数、疼痛评分、关节活动情况及不良反应发生率。

结果观察组总有效率高于对照组（91.67% vs 66.67%），差异有统计学意义（χ2=4.547，P<0.05）。

治疗后，观察组CRP、ESR水平分别为（10.05±1.22）mg/L、（21.03±3.84）mm/h，低于对照组的（17.21±2.05）mg/L、（26.62±4.33）mm/h，差异有统计学意义（t=14.704、4.732，P< 0.05）。

观察组患者关节压痛数、关节肿胀数分别为（3.95±0.89）、（4.52±1.36）个，低于对照组的（9.58±2.31）、（8.97±2.46）个，差异有统计学意义（t=11.142、7.756，P<0.05）。

观察组VAS评分、DAS28评分为（2.35±0.48）分、（2.30±0.28）分，低于对照组的（4.10±1.11）分、（3.87±0.42）分，差异有统计学意义（t=7.089、15.237，P<0.05）。

观察组不良反应发生率低于对照组（8.33% vs 12.50%），但差异无统计学意义（P>0.05）。

克隆巴哈阿尔法系数

克隆巴哈阿尔法系数英文回答：Cronbach's Alpha Coefficient: A Measure of Internal Consistency.Cronbach's alpha coefficient is a measure of internal consistency, which is the extent to which the items in a test or scale measure the same underlying construct. It is calculated by comparing the variance of the individual item scores to the variance of the total score. A higher alpha coefficient indicates that the items are more highly correlated with each other, and therefore that the test or scale is more reliable.Cronbach's alpha coefficient is typically reported as a value between 0 and 1. A value of 0 indicates that the items are not correlated at all, while a value of 1 indicates that the items are perfectly correlated. In general, a Cronbach's alpha coefficient of 0.7 or higher isconsidered to be acceptable. However, the acceptable level of Cronbach's alpha coefficient may vary depending on the purpose of the test or scale.Cronbach's alpha coefficient can be used to assess the reliability of a test or scale. A high Cronbach's alpha coefficient indicates that the test or scale is reliable, meaning that it consistently measures the same underlying construct. A low Cronbach's alpha coefficient indicatesthat the test or scale is not reliable, meaning that it may not consistently measure the same underlying construct.There are a number of factors that can affectCronbach's alpha coefficient, including the number of items in the test or scale, the difficulty of the items, and the correlation between the items. In general, a test or scale with a larger number of items, easier items, and higher correlations between the items will have a higherCronbach's alpha coefficient.Cronbach's alpha coefficient is a valuable tool for assessing the reliability of a test or scale. A highCronbach's alpha coefficient indicates that the test or scale is reliable, meaning that it consistently measuresthe same underlying construct. A low Cronbach's alpha coefficient indicates that the test or scale is not reliable, meaning that it may not consistently measure the same underlying construct.中文回答：克隆巴哈阿尔法系数，内部一致性的一种衡量标准。

MeV Quasar Observations with the COMPTON Gamma Ray Observatory

MeV Quasar Observations with the COMPTON Gamma Ray Observatory 1. Introduction
Extragalactic gamma-ray astronomy barely existed prior to the launch of the COMPTON Gamma Ray Observatory (CGRO) but there were good indications that this is a potentially very promising eld of research. Particularly good indicators were the detections of 3C273 by the COS-B satellite at energies above 50 MeV (suggesting a peak energy output in the MeV range) and the detections of Cen A and NGC 4151 at MeV energies (Refs. 1-3). Since most of the COS-B observations were concentrated along the galactic plane, there was some hope that the CGRO pointings away from the plane might show additional active galactic nuclei (AGNs). This expectation has been borne out, since the four instruments on CGRO have detected a surprisingly large number (> 35) of acti two years of the mission. In accordance with the topic of the workshop, only observations of time variability in the gamma-ray and optical emission of the AGNs and quasars will be addressed in the following.

1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。

a rXiv:076.384v1[astro-ph]21J un27VLA H53αobservations of the central region of the Super Star Cluster Galaxy NGC 5253C.A.Rodr´ıguez-Rico 1,2carlos@astro.ugto.mx W.M.Goss 3mgoss@ J.L.Turner 4turner@ Y.G´o mez 2y.gomez@astrosmo.unam.mx ABSTRACT We present observations in the H53αline and radio continuum at 43GHz carried out with the VLA in the D array (2′′angular resolution)toward the starburst galaxy NGC 5253.VLA archival data have been reprocessed to produce a uniform set of 2,1.3and 0.7cm high angular (0.′′2×0.′′1)radio continuum images.The RRL H53α,a previously reported measurement of the H92αRRL ﬂux density and the reprocessed high angular resolution radio continuum ﬂux densities have been modeled using a collection of HII regions.Based on the models,the ionized gas in the nuclear source has an electron density of ∼6×104cm −3and an volume ﬁlling factor of 0.05.A Lyman continuum photonproduction rate of 2×1052s −1is necessary to sustain the ionization in the nuclear region.The number of required O7stars in the central 1.5pc of the supernebula is ∼2000.The H53αvelocity gradient (10km s −1arcsec −1)implies a dynamical mass of ∼3×105M ⊙;this mass suggests the supernebula is conﬁned by gravity.Subject headings:galaxies:individual(NGC5253)--galaxies:starburst--radiolines1.INTRODUCTIONNGC5253is a blue dwarf irregular galaxy(located at∼4Mpc;Saha et al.1995)with an infrared luminosity of∼2×109L⊙(Beck et al.1996).NGC5253hosts several groups of young star clusters,called super star clusters(SSC)(Gorjian1996;Calzetti et al.1997). The optical spectrum of NGC5253shows signatures of large numbers of Wolf-Rayet(WR) stars(Campbell,Terlevich&Melnick et al.1986;Walsh&Roy1989;Schaerer et al.1997).A nearlyﬂat radio continuum spectra(see Fig.1)also indicates that free-free emission is the dominant emission mechanism and that NGC5253is a young starburst galaxy.The VLA observations made with similar angular resolution(1′′−2′′)at6,3.6and2cm (Beck et al.1996and Turner,Ho&Beck1998)reveal a complex structure in the central 20′′×40′′region,dominated by a compact source(≤1′′;1′′∼15pc).VLA observations of NGC5253,made with higher angular resolution at1.3(0.′′33×0.′′12)and2cm(0.′′22×0.′′08) reveal two compact sources.The main source has a deconvolved angular size of0.′′10×0.′′05 which corresponds to∼1−2pc(Turner,Beck&Ho2000).NICMOS observations show the presence of a double cluster in the nucleus of the galaxy separated by6−8pc(∼0.′′5) (Alonso-Herrero et al.2004)which may be related with the double radio nebula detected by Turner,Beck&Ho(2000).Higher angular resolution observations at0.7cm(74×17mas) show that the stronger component of the double nebula is compact,but partially resolved at scales of0.′′05(Turner&Beck2004).The main compact radio source(Turner,Ho& Beck1998)was named“the supernebula”.Beirao et al.(2006),based on mid-IR SPITZER observations from NGC5253,report that mid-IR emission is dominated by an unresolved cluster,coincident with the compact supernebula.Beirao et al.(2006)also observed an anticorrelation between PAH strength and UV radiation,suggesting destruction of PAH molecules in the central region.Based on1.3and2cm wavelength observations,Turner,Ho&Beck(2000)propose that the dominant radio source is a strong candidate for a globular cluster in the process of formation.The supernebula is visible at radio and infrared frequencies with no obvious optical counterpart.This supernebula is partially optically thick at2cm with an electron density of∼4×104cm−3(Meier et al.2002),typical of compact young(∼105yr)HII regions in our galaxy(Wood&Churchwell1989).Radio and infrared observations require a Lyman continuumﬂux of4×1052s−1,equivalent to a few thousand O7stars(Gorjian et al.2001). The radio recombination line H92αhas been observed toward the supernebula and has beeninterpreted as arising from gas around a SSC(Mohan et al.2001).Infrared Bracketαandγrecombination line observations revealed that the gas in the nebula is potentially bound by gravity(Turner et al.2003).Based on0.7cm wavelength observations,Turner&Beck(2004) conﬁrm that the supernebula is a giant compact HII region that is gravitationally bound. In order to reproduce the radio continuum emission,the nebula requires the excitation of ∼4000O7stars within the central5pc region(Turner,Beck&Ho2000).In this paper we present observations of the RRL H53αtoward NGC5253using the VLA.The H53αRRL provides information of the physical properties of the optically thin ionized gas in the supernebula.In Section2the technical details of the observations are presented.In Section3we present the results,while in Section4we provide the discussion. In Section5we present the summary.2.VLA Observations.2.1.H53αline.The H53αline(νrest=42951.9MHz)was observed in the D conﬁguration of the VLA on 2004,May31and June02,11,12,and13.We used observation cycles with integration times of10min on NGC5253and1min on the phase calibrator J1316-336(∼1.5Jy displaced by6◦).Two frequency windows(LOs)were used to observe the RRL H53α,centered at 42885.1and42914.9GHz.For each frequency window,the on-source integration time was ∼2hrs,using the mode of15spectral channels with a channel separation of3.125MHz (∼22km s−1).The data calibration was carried out for each frequency window using the continuum channel,consisting of the central75%of the band.Theﬂux density scales were determined from observations of J1331+305(3C286;1.47Jy).The bandpass response of the instrument was corrected using observations of J1337-129(∼9.5Jy).The parameters of the observations are summarized in Table1.The coordinates listed in this Table1corresponds to the center of the observations.In order to track reliably the phase variations introduced by the troposphere,the calibration of the data was performed correcting for the phases in aﬁrst step and subsequently correcting for both amplitude and phase.The line data cubes were Hanning-smoothed to reduce the Gibbs eﬀect and theﬁnal velocity resolution is∼44km s−1.The line data were further calibrated using the solutions obtained by self-calibrating the continuum channel of each frequency window.The radio continuum images were obtained by combining the continuum channels of each frequency window using the task DBCON from AIPS,and the self-calibration method was also applied to this combined data.The continuum emission was subtracted for each frequency window using the AIPS task UVLSF with a zero order polynomialﬁt based on the line free channels.The H53αline cubes and the43GHz continuum image were made using a natural weighting scheme and then convolved to obtain a circular Gaussian beam of2.′′0(P.A.=0◦).The combination of the diﬀerent frequency windows was carried out following a similar method to that used for the H53αline observed toward M82(Rodr´ıguez-Rico et al.2004);the two line cubes were combined into a single line cube after regridding in frequency the line data for each frequency window.This process was carried out using the GIPSY reduction package and a total of19velocity channels were obtained after putting together the two LO windows.The total line bandwidth,after combining all the windows,is about60MHz(400km s−1).2.2.Radio continuum at2cm,1.3cm and0.7cmIn addition to the continuum emission at0.7cm,obtained from the line-free channels of the H53αline observations(at angular resolution of2.′′0),we have included archive continuum data in the analysis.VLA continuum observations at2,1.3and0.7cm made with higher angular resolution(<1′′)toward NGC5253have been reprocessed from the VLA archive and used here to determine the properties of the continuum of the nuclear regions of NGC5253 over angular scales less than7′′.The observations at2and1.3cm were made with the A conﬁguration of the VLA on1998April9(Turner,Beck&Ho2000).The observations at0.7cm were made with the VLA in the A conﬁguration including Pie Town on2002 March9(Turner&Beck2004).The phase calibrator for the0.7cm is J1316-336(J2000). Absoluteﬂux density calibration for all the2cm,1.3cm and0.7cm observations was based on observations of3C286.The data at the three frequencies was brought to the same angular resolution by suitable choices of both weighting in the uv plane and uv range selection.The ﬁnal angular resolution of all three images is0.′′2×0.′′1(P.A.=0◦).3.RESULTSFigure1shows spectrum made with the low angular resolution(≥2”)observations summarized in Table2.These low angular resolution observations refer to the whole of the nucleus of NGC5253.This spectrum is nearlyﬂat in the frequency range1-230GHz.As noted before by Meier et al.(2002),a single component that consists of optically thin free-free extended emission(S∝ν−0.1)does not explain the observedﬂux densities at frequencies 10GHz.An optically thick free-free component with an electron density of∼6×104cm−3 is necessary to explain the observedﬂux densities in the frequency range of1−230GHz; this optically thick free-free component has a turnover frequency at∼9GHz.The electron density value of the compact ionized gas component was obtained based on high angularresolution radio observations and theﬁt is described in Section4.2.There are at least three non-thermal components with angular sizes between1′′and4′′,which only contribute about2mJy at6cm and1mJy at2cm(see Turner,Ho&Beck1998).Turner,Ho& Beck(1998)report three non-thermal sources based on observations at2and6cm,located near(east,southeast and northwest)the central super star cluster.Thus,a third non-thermal(S∝ν−0.75)component with S6cm=2mJy has also been used in theﬁt of the total continuum emission shown in Figure1.Theﬂux density level of the extended optically-thin component isﬁt to theﬂux density values obtained from subtraction of the optically thick free-free and the synchrotron emission from the observed totalﬂux densities.Figure2shows the43GHz radio continuum observations carried out in the D-array of the VLA(at2′′angular resolution).The integrated43GHz continuumﬂux density measured at this angular resolution is45±4mJy.The radio continuum emission at43GHz extends ∼30′′in the N-S direction and∼10′′in the E-W direction.The extended emission along the N-S direction agrees with previous observations at6,3.6and2cm(Turner,Ho&Beck1998). The central region dominates the continuum emission and has a deconvolved angular size of∼1.′′0at43GHz.The position of the43GHz continuum peak(∼27mJy beam−1)isα(2000)= 13h39m55.s97±0.1,δ(2000)=−31◦38′24.′′4±0.1,in agreement with previous observations at2and1.3cm(Turner,Beck&Ho2000).The position of the43GHz continuum emission peak is coincident with the position of the source labeled“source A”by Turner,Ho&Beck (1998).Figure3shows the H53αline velocity-channel images of NGC5253at an angular reso-lution of2′′.The H53αline emission is observed in the heliocentric velocity range∼340to 450km s−1.The peak H53αlineﬂux density is∼3.6mJy beam−1.The deconvolved angular size measured in the H53αline is∼1.′′0.We have obtained the1.6µm NICMOS image from the HST archive in order to compare the H53αRRL with the IR emission;the plate scale of the NICMOS observations is0.′′034.Following Turner et al.(2003)we have assumed that the brightest source in the1.6µm NICMOS can be identiﬁed with the radio peak as observed at an angular resolution of2′′.We thus have shifted the NICMOS image by∼1′′in the NE direction in order that the IR and radio peaks coincide,consistent with the astrometrical precision of HST.Figure4shows the overlay of the integrated H53αline emission on the 1.6µm after shifting the IR image.The integrated H53αline(0.31±0.03Jy km s−1),as obtained from a gaussianﬁt,has a peak lineﬂux density S L=5.3±0.6mJy,a FWHM of 58±12km s−1and a central heliocentric velocity of397±5km s−1.The velocity integrated H53αline emission is shown in Figure5.4.DISCUSSION4.1.Total radio continuum emissionThe spatially integrated radio continuumﬂux density obtained with low angular res-olution,S43GHz≃45mJy is comparable with previous measurements from interferometric observations carried out in the wavelength range of21to0.13cm(1.4−230GHz).Previous observations have revealed that the radio continuum emission at43GHz is dominated by thermal free-free emission(Beck et al.1996)and our43GHz radio continuum observations suggest that the contribution from non-thermal emission is negligible at wavelengths shorter than6cm(>5GHz,see Figure1).Thus,no contribution from synchrotron sources will be considered in the radio continuum emission models(see Section4.2).4.2.Models of a collection of HII regionModels that consist of HII regions have been used to estimate the electron density of the ionized gas in starburst galaxies like M82(Rodr´ıguez-Rico et al.2004),NGC253 (Rodr´ıguez-Rico et al.2006)and Arp220(Anantharamaiah et al.2000;Rodr´ıguez-Rico et al.2005).The models are constrained by:1)the physical diameter of the region associated with the RRLs emission and2)the measured radio continuum and RRLﬂux densities.The RRLs H92α(Mohan et al.2001)and H53αare used,along with the high-angular resolution radio continuum observations described in Section2.2,to estimate the electron density of the ionized gas in NGC5253.Based on the high angular resolution VLA archival observations(0.′′2×0.′′1),described in Section2.2the deconvolved angular size of the compact nuclear region is∼0.′′1(∼1.5pc). The peak position measured in these high angular resolution radio continuum images agrees with the peak position of the RRLs H53αand H92α(Mohan et al.2002).Thus,it is assumed that the H53αand the H92αRRLs arise from the same∼1.5pc(∼0.′′1)region. The radio continuumﬂux densities,at0.′′2×0.′′1angular resolution,are S2cm=9.3±1mJy, S1.3cm=11±1mJy and S0.7cm=9.5±1mJy.The velocity integrated H53αand H92αline emission are50mJy km s−1and203mJy km s−1,respectively.Acceptable models are those that can reproduce the continuumﬂux densities and the velocity integrated line emission on both RRLs.Based on the size measured in the radio continuum images,the maximum volume that this collection of HII regions may occupy is the volume of a spherical1.5pc region.Following the procedure listed in Rohlfs et al.1996,we use models that consist of HIIregions ionized by O7early-type stars(1049Lyman continuum photons s−1).The emission measure of each HII region is EM C=2n2e l.The continuum optical depth is(Altenhoﬀet al.1960)τc=8.235×10−2 T e GHz −2.1 EMmJy=3.07×107 νK .(2)The electron temperature of the thermally ionized gas is assumed to be T e=104K and νis the frequency.The radio continuumﬂux density(S cth)for each HII region in the models is given by:S cthmJyΩmJy= Bνsterad τc+b nτ∗LkHz −1.0 νK−1.15 EM LComparison of the velocity integrated H53αline emission and NICMOS images at1.6µm (Figure4)suggests that the radio supernebula has a close counterpart in infrared.Previous observations revealed the radio supernebula is associated with the brightest Brackett line source in NGC5253(Turner et al.2003).The dust extinction in the infrared at1.6µm is evident(Figure4)as the NICMOS image reveals a very compact emission toward the supernebula compared to the radio image in H53αintegrated line emission.Based on the velocityﬁeld,a velocity gradient of∼10km s−1arcsec−1is observed,suggesting an apparent rotation of the ionized gas in the supernebula;the nearly parallel isovelocity contours suggest rotation in the supernebula(see Figure7).The dynamical mass M sin i in the supernebula, with physical size of∼1.5pc,is∼3×105M⊙.This mass is comparable to the mass estimated for the nebula to be in virial equilibrium(∼4×105M⊙,Turner&Beck2004). Turner&Beck(2004),based on the H92αand the Brγline FWHM(∼75km s−1),concluded that the supernebula is gravity bounded.The mass implied by the velocity gradient is consistent with the luminosity implied by starburst models with this N Lyc(Leitherer et al.1999).The H53αline FWHM of58±5km s−1conﬁrms that the supernebula is gravity bounded.The diﬀerence in the line widths is interpreted as contribution of the extended ionized gas component to the Brγand H92αlines compared to the H53αline that traces mostly the compact ionized gas component.5.CONCLUSIONSThe H53αline and the radio continuum emission at43GHz were observed with the VLA in the D array toward the galaxy NGC5253.VLA archival data have been reprocessed to produce a uniform set of2,1.3and0.7cm continuum images with angular resolution of0.′′2×0.′′ing a single density model to reproduce the observed radio continuum at 2,1.3and0.7cm as well as the H53αand H92αRRL emission in the central compact region(∼1.5pc),the average electron density of the ionized gas is∼6×104cm−3.The 43GHz radio continuum emission arise from an optically thin free-free emission source.The Lyman continuum photons rate of∼2×1052s−1is necessary to sustain the ionization in the 1.5pc in the inner region of the galaxy NGC5253,corresponding to∼2000O7stars.The peak of the H53αline emission coincides with the brightest source observed in the1.6µm IR image within1′′.The velocity gradient measured in the H53αline(10km s−1arcsec−1), if interpreted as rotation,implies a dynamical mass of∼3×105M⊙within the central 20pc.The rough agreement of the mass derived from the apparent rotation with the mass estimated from the observed Lyman continuum rate,N Lyc,suggests that the gas motion within the supernebula is governed by gravity.The National Radio Astronomy Observatory is a facility of the National Science Foun-dation operated under cooperative agreement by Associated Universities,Inc.CR and YG acknowledge support from UNAM and CONACyT,M´e xico.REFERENCESAlonso-Herrero,A.,Takagi,T.,Baker,A.J.,Rieke,G.H.,Rieke,M.J.,Imanishi,M., Scoville,N.Z.,2004,ApJ,612,222Altenhoﬀ,W.,Mezger,P.G.,Wendker,H.,and Westerhout,G.,1960,Veroﬀ.Sternwarte, Bonn,No.59,48Anantharamaiah,K.R.,Viallefond,F.,Mohan,Niruj R.,Goss,W.M.,Zhao,J.H.,ApJ, 537,613Beck,S.C.,Turner,J.L.,Ho,P.T.P.,Lacy,J.H.,&Kelly,D.,1996,ApJ,457,610 Campbell,A.,Terlevich,R.,Melnick,J.,1986,MNRAS,223,811Gorjian,V.,Turner,J.L.,&Beck,S.C.,2001,ApJ,554,L29Herrero et al.,1992,A&A,261,209Meier,D.,Turner J.L.,&Beck,S.,2002,AJ,124,877Mohan,N.,Anantharamaiah,K.R.,&Goss,W.M.,2001,ApJ,557,659Rohlfs,K.,1986,Tools of Radio Astronomy,ed.Springer-Verlag,248-249Rodr´ıguez-Rico,C.A.,Viallefond,F.,Goss,W.M.,Zhao,J.-H.,&Anantharamaiah,K.R., 2004,ApJ,616,783Rodr´ıguez-Rico,C.A.,Goss,W.M.,Viallefond,F.,Zhao,J.-H.,G´o mez,Y.,&Ananthara-maiah,K.R.,2005,ApJ,633,198Rodr´ıguez-Rico,C.A.,Goss,W.M.,Zhao,J.-H.,G´o mez,Y.,&Anantharamaiah,K.R., 2006,ApJ,644,914Saha,A.,Sandage,A.,Labhardt,L.,Schwengeler,H.,Tammann,G.A.,Panagia,N.,& Macchetto,F.D.,1995,ApJ,438,8Schaerer,D.,Contini,T.,Kunth,D.,&Meynet,G.,1997,ApJ,481,75Turner,J.L.,Beck,S.C.,&Hurt,R.,1997,ApJ,474,L11Turner,J.L.,Ho,P.T.P.,&Beck,S.C.,1998,AJ,116,1212Turner,J.L.,Beck,S.C.,&Ho,P.T.P.,2000,ApJL,532,109Turner,J.L.,Beck,S.C.,Crosthwaite,L.P.,Larkin,J.E.,McLean,I.S.,&Meier,D.S., 2003,Nature,423,621Turner,J.L.,&Beck,S.C.,2004,ApJL,602,85Walsh,J.R.,Roy,J.-R.,1989,MNRAS,239297Wood,D.O.S.,Churchwell,E.,1989,ApJS,69,831Table1.Observing parameters for NGC5253using the VLA.Parameter H53αRRL(43GHz)Table2.Radio continuumﬂux densities for NGC5253. Wavelength Flux density Angular resolution Reference (cm)(mJy)a Values obtained by integrating over the central20′′×40′′region and used to obtain the total radio continuum spectrum (Figure1).All values were obtained from the literature except the value at0.7cm.b Values were obtained from the reprocessed VLA data(see Section2.2)integrating over the inner0.′′4.These values were used in the models of a collection of HII regions(Figure6). References.—(1)Turner,Ho&Beck(1998),(2)Mohan, Anantharamaiah&Goss(2001),(3)This paper,(4)Turner, Beck,&Hurt(1997),(5)Meier,Turner&Beck(2002).0.11101001 10 100I n t e g r a t e d c o n t i n u u m f l u x d e n s i t y (m J y )Frequency (GHz)observations +total ff + NT ff compact ff extendedNTFig. 1.—Total radio continuum spectrum of NGC 5253over the frequency range of 1to 230GHz.The total values are determined over a region of 20′′×40′′with low angularresolution ≥2′′.The long dashed line represents the optically-thick compact (<1.5pc,0.′′1)component determined from high-angular resolution observations over the inner 0.′′4(6pc).The short dashed line is the extended (>1.5pc,0.′′1)optically-thin component (S ∝ν−0.1).The dotted line is the total synchrotron emission (S ∝ν−0.75)obtained from measurements at 5GHz (Turner,Ho &Beck 1998).The solid line is the combined ﬁt to the total observed continuum ﬂux densities (listed in Table 2).510152025D E C L I N A T I O N (J 2000)RIGHT ASCENSION (J2000)13 39 56.856.656.456.256.055.855.655.455.255.0-31 38 1015202530354045Fig.2.—Radio continuum image of NGC 5253at 43GHz obtained using the VLA in the D array.Contour levels are drawn at −3,3,5,10,20,30,40,60,80,and 90times the rms of 0.13mJy beam −1.The cross shows the position of the 43GHz continuum peak.The angular resolution is 2′′.-31 38 202224262830341.3 KM/S 362.3 KM/SD E C L I N A T I O N (J 2000)-31 38 202224262830383.4 KM/S 404.4 KM/SRIGHT ASCENSION (J2000)13 39 56.456.256.055.855.6-31 38 202224262830425.4 KM/S 446.5 KM/SFig.3.—Channel images of the H53αline emission (contours)toward NGC 5253obtained using the VLA in the D array.Contours are −3,3,4,5,6,7,and 8times 0.4mJy beam −1,the rms noise.The cross shows the position of the 43GHz radio continuum peak.The synthesized beam (2′′)is shown in the ﬁrst panel.The central heliocentric velocity is listed for each image.55.655.813:39:56.056.256.428.024.0-31:38:20.0Fig.4.—Overlay of the velocity integrated (moment 0)of the H53αline emission (contours)toward NGC 5253using the VLA in the D array and the H band image from NICMOS (F160W,1.6µm )toward NGC 5253.The NICMOS image has been shifted ∼1′′to the NE (consistent with the astrometrical precision of HST)in order that the peak of the H53αline emission coincides with the peak of the IR.Contour levels are drawn at 5,10,20,30,...,90,95%the peak line emission of 0.36Jy beam −1km s −1.The cross shows the peak of the 43GHz continuum emission.The HPFW for the H53αline image is 2′′.-1 01234 56100150 200 250300 350 400 450 500 550F l u x d e n s i t y (m J y )Heliocentric velocity (km/s)Fig.5.—Total integrated H53αspectrum from NGC 5253,obtained by integrating over the central diameter of 2′′.The thick line shows the data and the dashed line shows the Gaussian ﬁt.The rms in the velocity range 150−300km s −1is 0.45mJy beam −1and 0.25mJy beam −1in the velocity range 350−450km s −1.0.1110100I n t e g r a t e d c o n t i n u u m f l u x d e n s i t y (m J y )Frequency (GHz)I n t e g r a t e d R R L f l u x d e n s i t y (m J y *k m /s )Frequency (GHz)Fig. 6.—Single density (n e =6×104cm −3)models for the continuum (top)and RRL (bottom)emission from the supernebula are shown as solid lines.Data points in the con-tinuum and RRL are marked by the ﬁlled squares.The models consist of a collection of HII regions with electron temperature of 104K.The radio continuum observations consistof the reprocessed archival data with 0.′′2×0.′′1angular resolution (listed in Table 2).The RRL observations are from this paper (H53α)and from Mohan et al.(2001)(H92α).These recombination lines arise from the compact (∼1.5pc)radio supernebula.380400420D E C L I N A T I O N (J 2000)RIGHT ASCENSION (J2000)13 39 56.456.356.256.156.055.955.8-31 38 2223242526272829Fig.7.—Velocity ﬁeld observed in the H53αline from NGC 5253.Contour levels are the heliocentric velocities at 380,390,400,410and 420km s −1.The grayscale shows the heliocentric velocity ﬁeld image in the H53αline.The cross shows the peak of the 43GHz continuum emission.The HPFW is 2′′.。