BHαBAR: big Hα kinematical sample of barred spiral galaxies – I. Fabry–Perot observations of 21 galaxies

We present the Hα gas kinematics of 21 representative barred spiral galaxies belonging to the BHαBAR sample. The galaxies were observed with FaNTOmM, a Fabry–Perot integral-field spectrometer, on three different telescopes. The three-dimensional data cubes were processed through a robust pipeline with the aim of providing the most homogeneous and accurate data set possible useful for further analysis. The data cubes were spatially binned to a constant signal-to-noise ratio, typically around 7. Maps of the monochromatic Hα emission line and of the velocity field were generated and the kinematical parameters were derived for the whole sample using tilted-ring models. The photometrical and kinematical parameters (position angle of the major axis, inclination, systemic velocity and kinematical centre) are in relative good agreement, except perhaps for the later-type spirals.     

On the emptiness of voids

The observability of a galaxy population inside of voids is estimated by assuming a void population similar to the one of nearby field galaxies in density as well as in morphological mixture. Obviously an extension to apparent magnitudes beyond m = 22 for a complete sample of galaxies in a sufficient large field is needed to get reliable information on a void population.     

Open star clusters in the spiral arms of our Galaxy

We consider the age distributions of open star clusters attributed to three segments of Galactic spiral arms. The smoothed distributions of clusters on the age-Galactocentric angle plane show a great nonuniformity. The time dependence of the formation rate of Galactic disk clusters recovered by taking into account selection effects and dynamical evolution of clusters shows that, on average, the formation rate of open star clusters decreases with time. This is in agreement with the increase in star formation rate into the past, as follows from the study of this process by the method of stellar population synthesis. The present time is the epoch of a current maximum of the cluster formation rate. In addition to the current maximum, there have been at least three more maxima with a period of 300–400 Myr and a duration of no more than 300 Myr. The age distributions are consistent with the pattern of star formation governed by the successive passages of density waves through each examined volume of the Galactic disk. The spiral structure becomes more complex when passing from the inner regions of the Galaxy to its outer regions.     

多层螺旋CT对结肠癌淋巴结转移的诊断价值

目的：初步评判多层螺旋CT淋巴结短长径比值联合相对强化值对结肠癌淋巴结转移的诊断价值。方法：收集我院肿瘤外科经结肠镜或手术病理确诊的结肠癌患者47例作为研究对象,进行腹部CT平扫和增强扫描。记录腹部可疑淋巴结短径、短-长径比值、平扫和动、静脉期CT值以及相对强化值各项参数,并以病理结果为金标准,进行ROC曲线绘制,并分析上述各个参数的诊断效能。结果：结肠癌转移淋巴结的短径、短长径比值、平扫和动、静脉期CT值以及相对强化值与非转移淋巴结比较均明显升高（P<0.01）。短径、短-长径比值、平扫和动、静脉期CT值以及相对强化值所绘制ROC曲线AUC分别为0.649、0.725、0.713、0.723、0.696和0.793,灵敏度分别为63.30%、76.70%、73.30%、60.00%、76.72%和73.30%,特异度分别为75.00%、70.00%、60.00%、75.00%、65.00%和90.00%;淋巴结短长径比值联合相对强化值ROC曲线AUC为0.908,敏感度为86.70%,特异度为85.00%,一致性分析显示Kappa系数为0.787,提示有较好的一致性。结论：多层螺旋CT淋巴结短-长径比值联合相对强化值对结肠癌淋巴结转移具有较高的特异度,可为临床判断淋巴结转移提供重要依据。     

16排螺旋CT3D及MIP在肝癌APS中的临床应用

目的:探讨16排螺旋CT三维及最大密度重建技术在肝癌动门脉分流诊断中的应用价值.方法:对64例肝癌伴动门脉分流患者的16排螺旋CT增强图像进行三维及最大密度重建,并对重建图像进行观察和分析(与CT轴位图像和数字减影血管造影图像进行对照).结果:16排螺旋CT三维及最大密度重建技术能全面、直观、多方位地显示肝癌动门脉分流的影像征象,并能较好显示动门脉分流导致的血液动力学改变.结论:16排螺旋CT三维及最大密度重建作为轴位CT图像的重要后处理技术,具有无创、直观、快速显示肝癌动门脉分流各种影像征象的特点,为临床诊断和治疗肝癌动门脉分流提供可靠的依据.     

台风螺旋雨带云结构和降水形成机制研究

应用数值模式结果,选择台风登陆后两个不同时次螺旋雨带中两个强降水中心,对台风螺旋雨带的云结构和降水形成机制进行诊断分析.结果发现螺旋雨带云结构和降水形成机制有如下特点:在9～13 km高空范围内冰晶的非均质核化非常活跃,冰晶转化率高于台风眼壁暴雨数倍,但是冰晶通过贝吉龙过程生长为雪、雪通过凝华增长生长为霰的过程相对台风眼壁很弱,螺旋雨带雨水形成微物理机制以霰粒子融化成雨水(pgmlt)为主,冰相粒子转化率大值区位于垂直上升气流大值区,8 km高度霰收集雪(dgacs)干增长是最主要的冰相粒子生长过程,与北方层状云比较,螺旋雨带暴雨冷云中的凝华过程和撞冻过程非常活跃.螺旋雨带云水凝结过程呈双峰型,位于7～8 km高度冷云区的云水凝结峰值较大,暖云区0.5～1.5 km高度云水凝结峰值次之.     

Review of the Study of Nonlinear Atmospheric Dynamics in China （1999-2002）

Researches on nonlinear atmospheric dynamics in China (1999-2002) are briefly surveyed. This review includes the major achievements in the following branches of nonlinear dynamics: nonlinear stability theory,nonlinear blocking dynamics, 3D spiral structure in the atmosphere, traveling wave solution of the nonlinear evolution equation, numerical predictability in a chaotic system, and global analysis of climate dynamics.Some applications of nonlinear methods such as hierarchy structure of climate and scaling invariance, the spatial-temporal series predictive method, the nonlinear inverse problem, and a new difference scheme with multi-time levels are also introduced.