Laboratory simulations of Titan's atmosphere: organic gases and aerosols

Titan, the main satellite of Saturn, has been observed by remote sensing for many years, both from interplanetary probes (Pioneer and Voyager's flybys) and from the Earth. Its N2 atmosphere, containing a small fraction of CH4 (approximately 2%), with T approximately 90 K and P approximately 1.5 bar at the ground level, is irradiated by solar UV photons and deeply bombarded by energetic particles, i.e. Saturn mangetospheric electrons and protons, interplanetary electrons and cosmic rays. The resulting energy deposition, which takes place mainly below 1000 km, initiates chemical reactions which yield gaseous hydrocarbons and nitriles and, through polymerisation processes, solid aerosol particles which grow by coagulation and settle down to the ground. At the present time, photochemical models strongly require the results of specific laboratory studies. Chemical rate constants are not well known at low temperatures, charged-particle-induced reactions are difficult to model and laboratory simulations of atmospheric processes are therefore of great interest. Moreover, the synthesis of organic compounds which have not been detected to date provides valuable information for future observations. The origin and chemical composition of aerosols depend on the nature of chemical and energy sources. Their production from gaseous species may be monitored in laboratory chambers and their optical or microphysical properties compared to those deduced from the observations of Titan's atmosphere. The development of simulation chambers of Titan's extreme conditions is necessary for a better understanding of past and future observations. Space probes will sound Titan's atmosphere by remote sensing and in situ analysis in the near future (Cassini-Huygens mission). It appears necessary, as a preliminary step to test on-board experiments in such chambers, and as a final step, when new space data have been acquired, to use them for more general scientific purposes.     

Highland-lowland conflict over natural resources: a case of Mae Soi,Chiang Mai,Thailand

Interviews were conducted among 150 Hmong highland and ethnic Thai lowland villagers during May-August 1992 in Chiang Mai in northern Thailand. Officials from national and international drug abuse control and development agencies were also interviewed. The aim was to determine the nature of the conflict between the highlanders and the lowlanders. The lowlanders perceived that the conflict was due to environmental causes brought on by the Hmongs' destruction of forest and pollution of the river. The Mai Soi stream that was relied on by lowlanders was viewed as threatened by drought and water reduction from forest destruction. Shinawatra researched water runoff from major rivers during seasonal changes and found reduced volume during 1970-80. Alford found no significant change in stream flow. 71% of lowlanders reported that stream flow was reduced over a 3-6 year period. 40% reported that the forests were fenced off in order to protect the forests, but 22% were forced by village headmen to do so. 32% were promised land in the allocation areas. The highlanders perceived the conflict in diverse ways. Many attributed the conflict to the murder of a lowlander cattle thief in a Hmong village in 1984. A 1983 report confirmed ethnic conflict and the killing and stealing of Hmong animals. Some highlanders and lowlanders believe the conflict arose due to one person, Ajahn Pongsak Techadhammo, who tried to create environmental awareness among all tribes and ethnic groups. He was against lowlanders' misuse of forests and wanted relocation of the hill tribes that cultivated opium. Social status differences fuel the conflict. Lowlanders consider themselves superior to hill tribes that do not speak Thai and are not Buddhists. The hill tribes create discord because of their economic success with cash crops. The authors recommend forest, soil, and water conservation among highlanders and lowlanders and broadening development to include other communities.     

World population in a grid of spherical quadrilaterals

"We report on a project that converted subnational population data to a raster of cells on the earth. We note that studies using satellites as collection devices yield results indexed by latitude and longitude. Thus it makes sense to assemble the terrestrial arrangement of people in a compatible manner. This alternative is explored here, using latitude/longitude quadrilaterals as bins for population information.... The results to date of putting world boundary coordinates together with estimates of the number of people are described. The estimated 1994 population of 219 countries, subdivided into 19,032 polygons, has been assigned to over six million five minute by five minute quadrilaterals covering the world."     

Comparison of Venusian Coronae with Giant Circumferential Dyke Swarms on Earth

正The surface of Venus features a large number(500)of quasi-circular tectono-magmatic features known as coronae.Coronae are characterized in part by their topographic characteristics,which can be diverse and     

Large Igneous Provinces,Their Giant Mafic Dyke Swarms,and Links to Metallogeny

正Giant mafic dyke swarms are a key component of the feeder system of Large Igneous Provinces(LIPs),large volume(0.1 Mkm~3;frequently above1 M km~3),mainly mafic(-ultramafic)magmatic events of intraplate affinity.     

Genesis and Distribution of Ultra-alkaline Magmatism within the East Antarctic Associated with the Kerguelen Plume Activity

正Alkaline magmatism is often associated with the initial or final stages of huge plume activity.The alkaline bodies are most often found within the boundary area of plume impact upon the continents.The initial stages of the     

I AND UTILIZATION IN KUNMING LAKE REGION, YUNNAN

The Kunming Lake, with an area of 324 sq. kin. during its flood water time, is the largest lake in Eastern Yunnan. More than twenty streams from the surrounding mountains empty into the lake which is drained by the TangLang River to the upper Yangtze. Around the Kunming Lake is an extensive     

On the Turtle Remains from the Archaeological Site of Anyaug,Houan

This paper embodies the results of a study of the turtle remainscollected during the systematic excavations on the archaeological site ofAnyang,the old capital of the Shang dynasty (circa 1400-1100 B.C.),started since 1928 by the Institute of History and Philology,AcademiaSinica.     

Hdrosweep DS多波束数据的精细后处理

我们开发了一套名为“MB－SEystem”的新软件包，用来处理和显示由R／V Mau-rice Ewing船采集的Hdrosweep DS多波束数据，这套新软件所包含的工具有：模式化声速剖面；根据声速剖面，利用射线追踪，由声波传播时间计算多波束测深值；对多波速测深值的人工交互和自动编辑；以及运算和显示多波速数据的其它各种工龄，一个模块化的输入／输出库允许MB－system程序存取和运算数据，这些数据可以是任何一种刈幅成图声纳数据格式所支持的数据，它可以收以下设备采集；Hdrosweep DS、“古典式”SeaBeam、SeaBeam2000、SeaBesm2100、H-MR1、Simrad EMl2及其它声纳设备。本文提供了一个利用该软件对最近由R/V Maurice Ewing船采集的Hydrosweep数据进行处理的应用实例。