Latitudinal and climatic distributions of 3D craniofacial features among Holocene populations

The geographical and climatic patterning in craniofacial morphology among recent hominids has been regarded as relatively reliable evidence of environmental adaptation and natural selection,which is largely attributed to thermoregulation.However,the relative influence of genetic and environmental factors on craniofacial features is unclear.Our study employed 3D laser scanning techniques to evaluate the association between geographical(latitude),climatic(annual temperature)factors,and 3D craniofacial measurements in 18 recent populations through bivariate correlation analysis.Significant correlations were found among braincase surface area,zygomatic bone surface area,cranial-facial index(facial surface area relative to braincase surface area)and local temperature,and a clear latitudinal gradient was also found in variation of braincase surface area.No significant correlations were found between zygomatic bone surface area,cranial-facial index and latitude.Our analysis supports the idea that the braincase functions as a radiator and is closely related to direct sunlight.We also suggest that absolute/relative craniofacial surface area varies consistently with predictions derived from Bergmann’s Rule.The mosaic craniofacial traits of American Indians may reflect retention of cold-derived,ancestral features,as well as a response to a slightly warmer climate.Because different craniofacial regions preserve environmental/genetic signatures differentially,caution is suggested when craniofacial anatomy is used for phylogenetic reconstruction and functional-morphological analysis.     

高频加热中低纬电离层激励不稳定性研究

高频泵波加热电离层实验二维数值模拟结果显示,虽然背景电离层状态能够明显影响模拟加热结果,但是在大部分平静电离层状态下,模拟加热一段时间后,加热区域内电子浓度、电子温度会趋于稳定,这一结论已为实验所证实.然而部分模拟结果显示,当电离层电子浓度、电子温度空间结构满足一定条件后,过密加热中泵波反射区域,电子浓度、电子温度在加热机开关机后将产生不稳定的时空效果.激发该不稳定性的正反馈过程如下：当泵波反射区域内电子温度受到泵波加热上升后,其引起的等离子体膨胀导致该区域内电子浓度减小,受到电子温度、电子浓度变化的共同影响,电子能量方程中由于电子-离子碰撞导致的电子能量损失项减小,电子温度将进一步升高,一种正反馈机制建立.最后得到以下结论,当电离层电子温度剖面呈明显的双峰结构,被加热区域内电子温度较高,且电子-离子碰撞引起能量损失项成为电子主要的能量损失项后,一种不稳定性被激发,加热将产生更明显的电子浓度、电子温度的变化.以上条件在下午电离层更容易被满足.     

桂林三叠世古地理古气候及热带岩溶发育程度探讨

文章对桂林三叠世时的古地理及古气候条件、晚三叠世内陆湖盆的发育及堆积物和残留特征进行了描述，探讨了中晚三叠世桂林热带岩溶发育的程度。认为中晚三叠世是桂林热带岩溶极为强烈发育时期，也是岩溶洞穴强烈发育的一个时期，从此奠定了桂林热带岩溶地貌轮廓雏形。迄后的地质历史中，其热带岩溶基本上是在此基础上的继承发育。     

Quantum wormhole with conformal scalar field

In this paper I use the Hartle-Hawking method to discuss quantum wormhole with conformal scalar field. I derive the corresponding Wheeler-De Witt equation, calculate the wormhole wave function, which is found to be the product of two harmonic solutions. Analysis of the wave function reveals that the probability density of the wormhole appearing at a = 0 is zero, that the most probable radius of the wormhole base state is the Planck length and that the wormhole is mostly likely to be in a state of small Φ value.     

天文经纬度和天文方位角测定的基本原理

大地天文测量无论在基础科学,还是在国民经济和国防建设中都具有重要的意义。随着空间大地测量技术(VLB、ILLR、SLR和GPS等)的发展,虽然天文测量在应用上有所减少,但在大地测量的绝对定位和中远程武器的发射等领域中仍然是不可替代的技术。本文详细地介绍了天文经纬度和天文方位角测量的基本原理和方法,综述了天文测量目前的发展状况和存在的问题。本文的工作可为天文大地测量的研究提供一定的参考和依据。     

1994年南海夏季风爆发的数值模拟和分析研究

1994年南海夏季风建立于5月第一候,利用MM5成功地模拟了这一过程,并通过敏感性试验,讨论了中纬度系统和中南半岛及其附近地区的积云对流对夏季风环流建立的影响,结果表明:(1)南下接近副热带一定强度的中纬度槽-锋系统的强迫,可引起南海地区副热带高压脊的减弱东撤,因而有利于南海夏季风的建立;(2)东移的中纬度高压脊与南亚高压的同相叠加是触发夏季风建立的重要因子之一,它引起南亚高压中心迅速北移至中南半岛的北部;(3)中南半岛及其附近地区的积云对流加热,对南海地区夏季风环流的建立也有重要的影响.     

Latitudinal patterns and influencing factors of soil humic carbon fractions from tropical to temperate forests

Soil humic carbon is an important component of soil organic carbon (SOC) in terrestrial ecosystems. However, no study to date has investigated its geographical patterns and the main factors that influence it at a large scale, despite the fact that it is critical for exploring the influence of climate change on soil C storage and turnover. We measured levels of SOC, humic acid carbon (HAC), fulvic acid carbon (FAC), humin carbon (HUC), and extractable humus carbon (HEC) in the 0–10 cm soil layer in nine typical forests along the 3800-km North-South Transect of Eastern China (NSTEC) to elucidate the latitudinal patterns of soil humic carbon fractions and their main influencing factors. SOC, HAC, FAC, HUC, and HEC increased with increasing latitude (all P<0.001), and exhibited a general trend of tropical < subtropical < temperate. The ratios of humic C fractions to SOC were 9.48%–12.27% (HAC), 20.68%–29.31% (FAC), and 59.37%–61.38% (HUC). Climate, soil texture, and soil microbes jointly explained more than 90% of the latitudinal variation in SOC, HAC, FAC, HEC, and HUC, and interactive effects were important. These findings elucidate latitudinal patterns of soil humic C fractions in forests at a large scale, and may improve models of soil C turnover and storage.     

等距离纬度等量纬度和等面积纬度展开式

对数学制图学中经常遇到的等距离纬度、等量纬度和等面积纬度展开式进行新的研究。借助计算机代数系统强大的数学分析功能,给出这些纬度用偏心率幂级数形式表示的正解公式,并且以此为基础,给出纬度用偏心率幂级数形式表示的反解展开式,与以往数值形式表示的反解公式不同,这些反解展开式是以符号形式给出,研究表明计算机代数系统的应用不但极大地提高公式推演的效率和准确度,而且反解系数可以表示为更简单和更便于记忆的符号形式。     

二维能量平衡模式对若干气候问题的研究

Based on a two-dimensional energy balance model, the studies on some climatic issues such as the re- lationship between ice cap latitude and solar constant, desertifieation, and the warming effect of carbon dioxide, have been reviewed and discussed. The phenomenon that a fixed solar constant might correspond to different equilibrium ice cap latitudes is determined by the continuity of albedo distribution. The disconti- nuity in albedo distribution increases the number of equilibrium ice cap latitudes. Desert would expand both northward and southward when desert surface albedo is increasing. This would deteriorate the ecological environment in border regions, and then threaten the existence of local inhabitants. Melting of the polar ice would not be accelerated, with increasing carbon dioxide concentration. The ice cap latitude would move northward slowly, with some “hiatus” periods, under the slowly increasing global average surface tempera- ture. According to the current research, future development of the two-dimensional energy balance model and possible progress are also forecasted.     

Modoki对南半球中高纬度气候及海冰异常的影响

利用诊断分析方法分析研究了热带太平洋ENSO Modoki现象对南半球中高纬度气候和海冰的影响。分析了ENSO Modoki现象的季节变化特征,并定义了ENSO Modoki的活跃年和活跃季节。利用偏相关分析、合成分析和超前滞后相关分析等诊断分析方法,分析了1979年1月到2010年12月间ENSO Modoki影响南半球中高纬气候及海冰异常的遥相关模态及可能的遥相关动力机制。研究结果显示费雷尔环流的异常变化是两者之间遥相关的可能方式。