Fullerenes in the cretaceous-tertiary boundary layer

High-pressure liquid chromatography with ultraviolet-visible spectral analysis of toluene extracts of samples from two Cretaceous-Tertiary (K-T) boundary sites in New Zealand has revealed the presence of C(60) at concentrations of 0.1 to 0.2 parts per million of the associated soot. This technique verified also that fullerenes are produced in similar amounts in the soots of common flames under ambient atmospheric conditions. Therefore, the C(60) in the K-T boundary layer may have originated in the extensive wildfires that were associated with the cataclysmic impact event that terminated the Mezozoic era about 65 million years ago.     

Impacts, tsunamis, and the haitian cretaceous-tertiary boundary layer

The marker bed at the Cretaceous-Tertiary boundary of the Beloc Formation (southern Haiti) contains abundant coarse-grained microtektites and minor amounts of shocked quartz grains in the basal part. The upper part is composed of medium-grained marl with amalgamated microtektite lenses and finer-grained marl lenses disseminated throughout. Field and petrographic observations, and the distribution of planktonic foraminifera suggest that the bed formed from a complex sequence of events. A bolide impact nearby produced microtektites that sett1led to form a nearly pure layer at the base. Vaporized materials with anomalously high extraterrestrial components settled last, along with carbonate sediments. The entire bed became sparsely consolidated. Subsequently, another major disruptive event, perhaps a giant tsunami, partly reworked the initial deposit. Cohesive fragments of the original marker bed mixed with exotic materials were redeposited as lenticular bodies. This process also may have caused further mixing of Cretaceous and Tertiary microfossils, as observed at Beloc and elsewhere.     

Particle nucleation in the tropical boundary layer and its coupling to marine sulfur sources

New particle formation in a tropical marine boundary layer setting was characterized during NASA's Pacific Exploratory Mission-Tropics A program. It represents the clearest demonstration to date of aerosol nucleation and growth being linked to the natural marine sulfur cycle. This conclusion was based on real-time observations of dimethylsulfide, sulfur dioxide, sulfuric acid (gas), hydroxide, ozone, temperature, relative humidity, aerosol size and number distribution, and total aerosol surface area. Classic binary nucleation theory predicts no nucleation under the observed marine boundary layer conditions.     

Simulated increase of hurricane intensities in a CO2-warmed climate

Hurricanes can inflict catastrophic property damage and loss of human life. Thus, it is important to determine how the character of these powerful storms could change in response to greenhouse gas-induced global warming. The impact of climate warming on hurricane intensities was investigated with a regional, high-resolution, hurricane prediction model. In a case study, 51 western Pacific storm cases under present-day climate conditions were compared with 51 storm cases under high-CO2 conditions. More idealized experiments were also performed. The large-scale initial conditions were derived from a global climate model. For a sea surface temperature warming of about 2.2 degrees C, the simulations yielded hurricanes that were more intense by 3 to 7 meters per second (5 to 12 percent) for wind speed and 7 to 20 millibars for central surface pressure.     

基于XPS的苹果表皮残留农药界面层的氩刻分析

针对果皮表面残留农药进行微观深度探测及分析。结果表明,苹果表皮氧乐果及敌敌畏随施药浓度及施药时间的残留沿纵向深度变化呈现非线性规律性,主要残留部位为果实表皮的角质层区距表面8μm,氧乐果残留分布的规律性强于敌敌畏。     

RFID技术及其在奶牛精细养殖数字化系统中的应用研究

数据流、信息流的采集、管理以及保持它们的动态性和现势性是精细养殖系统的关键问题之一。本文介绍了射频识别（RFID）系统的概念和工作原理，提出了以数据处理为基础的奶牛精细养殖数字化系统的体系结构，并做了基于RFID／传感器的系统物理设计。     

Deconvolution of the factors contributing to the increase in global hurricane intensity

To better understand the change in global hurricane intensity since 1970, we examined the joint distribution of hurricane intensity with variables identified in the literature as contributing to the intensification of hurricanes. We used a methodology based on information theory, isolating the trend from the shorter-term natural modes of variability. The results show that the trend of increasing numbers of category 4 and 5 hurricanes for the period 1970-2004 is directly linked to the trend in sea-surface temperature; other aspects of the tropical environment, although they influence shorter-term variations in hurricane intensity, do not contribute substantially to the observed global trend.     

极端干旱区大气边界层厚度时间演变及其与地表能量平衡的关系

主要采用ECMWF的地表和大气产品分析了中国西北极端干旱区大气边界层厚度与地表能量通量的时间变化特征,同时,结合探空加强观测分析了大气边界层演变的可能因素.得出:西北极端干旱区大气边界层厚度呈现出季节性的年际和年代际变化,夏季大气边界层厚度呈下降趋势,春、秋季节呈现出先增加后降低的趋势,冬季以阶段性降低趋势为主,20世纪80年代是大气边界层厚度的转折时期;感热通量是极端干旱区大气边界层发展的主要热力因素;由于夏季净辐射量、地气温差、粗糙度以及风速等因子随时间演变而呈降低趋势,潜热通量呈增加趋势,导致了边界层高度形成的热力作用减弱,边界层厚度降低;同时,粗糙度和风速也是大气边界层发展的主要动力因素,由于边界层粗糙度和风速降低,促使垂直风切变减小,湍流动力作用减弱,也会导致边界层厚度降低.     

WRF微物理和边界层组合方案对气旋过境海气通量模拟的敏感性研究

利用中尺度模式WRF (Weather Research and Forecasting Model)3.2版本模拟了一次冬季温带气旋过境过程,分析海气通量模拟对9种微物理方案和3种行星边界层方案的敏感性。LIN方案和YSU方案组合实验模拟出的平均风速最大,WSM3方案和ACM2方案组合平均风速最小。总体上,边界层方案对感热和潜热模拟的影响大于微物理方案的影响,风暴过境前,各实验模拟的海气通量对参数化选择不敏感;风暴期间,不同边界层参数化方案风速模拟差异较大,气温也存在差异,从而导致感热模拟差异较大;风暴过后,不同参数方案感热和潜热模拟差异较大,主要由于风速、气温和比湿综合作用导致。各种组合模拟出的海气通量均存在系统误差,这主要受近地面边界层方法限制,因此WRF 3.2还需进一步改善。     

Modulation of hurricane activity in the gulf of mexico by the madden-julian oscillation

The Madden-Julian oscillation (MJO) is a large-scale episodic modulation of tropical winds and precipitation that travels eastward from Asia to America, with a characteristic repeat time of 30 to 60 days. Here it is shown that when MJO wind anomalies in the lower troposphere of the eastern Pacific are westerly, Gulf of Mexico and western Caribbean hurricane genesis is four times more likely than when the MJO winds are easterly. Accurate predictions of the MJO may lead to improved long-range forecasts of tropical cyclone activity.     

Salt fingers observed in the mediterranean outflow

Salt fingers, convection cells which constitute a possible mixing mechanism of the ocean, have now been observed in the Mediterranean outflow. The fingers, 6 millimeters in diamneter and 24 centimeters long, were photographed below the salinity maximum of the outflow, in an interface 22 centimeters thick where temperature and salinity decreased O. 15 degrees C and 0.03 per mil, respectively.     

农田-草地景观镶嵌体土壤水分界面瞬时判定初探

采用地统计学方法和Lattice Wombling界面判定方法对典型农牧交错带(河北沽源地区)农田-草地景观镶嵌体土壤水分界面的瞬时界面因子空间特征进行初探.结果表明:利用地统计学对不同粒度的土壤水分空间特征研究验证土壤水分界面存在,且存在不同生态梯度效应.应用Lattice Wombling界面判定方法对农田-草地界面土壤水分进行界面的瞬时判定表明,农田-草地界面土壤水分界面的判定呈不规则曲线的界面变化;农田-草地界面土壤水分界面的界面因子(BE)在农田内部较为明显,在距农田草地边界农田一侧的3~7 m处和草地内部3 m处左右.     

Intense Natural Selection in a Population of Darwin's Finches (Geospizinae) in the Galapagos

Survival of Darwin's finches through a drought on Daphne Major Island was nonrandom. Large birds, especially males with large beaks, survived best because they were able to crack the large and hard seeds that predominated in the drought. Selection intensities, calculated by O'Donald's method, are the highest yet recorded for a vertebrate population.     

Dissipation of marine stratiform clouds and collapse of the marine boundary layer due to the depletion of cloud condensation nuclei by clouds

When the production of cloud condensation nuclei in the stratocumulus-topped marine boundary layer is low enough, droplet collisions can reduce concentrations of cloud droplet numbers to extremely low values. At low droplet concentrations a cloud layer can become so optically thin that cloud-top radiative cooling cannot drive vertical mixing. Under these conditions, model simulations indicate that the stratocumulus-topped marine boundary layer collapses to a shallow fog layer. Through this mechanism, marine stratiform clouds may limit their own lifetimes.     

Lattice effects observed in chaotic dynamics of experimental populations

Animals and many plants are counted in discrete units. The collection of possible values (state space) of population numbers is thus a nonnegative integer lattice. Despite this fact, many mathematical population models assume a continuum of system states. The complex dynamics, such as chaos, often displayed by such continuous-state models have stimulated much ecological research; yet discrete-state models with bounded population size can display only cyclic behavior. Motivated by data from a population experiment, we compared the predictions of discrete-state and continuous-state population models. Neither the discrete- nor continuous-state models completely account for the data. Rather, the observed dynamics are explained by a stochastic blending of the chaotic dynamics predicted by the continuous-state model and the cyclic dynamics predicted by the discrete-state models. We suggest that such lattice effects could be an important component of natural population fluctuations.     

自散焦介质对非线性热像的抑制效应

理论分析了运用自散焦介质抑制热像的可行性,进而通过数值模拟方法,研究了自散焦介质对强激光通过自聚焦介质非线性热像的抑制效应.结果表明,自散焦介质放置在自聚焦介质的前面或后面均能有效地抑制热像形成,但较厚自散焦介质后置情况的热像抑制效果好于前置情况,且自散焦介质与自聚焦介质越薄,二者之间的间隙越小,抑制效果越好.