The N-gon is not a local minimum of U 2 I for N > 7

A theorem of Palmore's concerning coplanar central configurations of equal mass bodies was shown to be false for all even N 6 by Slaminka and Woerner. Using a variation of that argument I prove that Palmore's Theorem is false for all N 6.Northwestern University     

Background to the Liberia and Sierra Leone implosions

Liberia and Sierra Leone are tragic examples of what happens when central authority collapses and warlords emerge as de-facto rulers over large portions of the national territory. Horrors inflicted on non-combatants and the well publicized trading in conflict diamonds served to focus world attention on these two small countries sharing a common border. Both countries have experienced mixed success with outside military intervention for peace keeping and nation building purposes. What has happened is all the more distressing when one considers each countrys prospects at birth under the political and economic aegis of arguably two of the most powerful and enlightened countries of the time, Great Britain in the case of Sierra Leone and the United States in Liberia.     

Background to the Liberia and Sierra Leone implosions

Liberia and Sierra Leone are tragic examples of what happens when central authority collapses and warlords emerge as de-facto rulers over large portions of the national territory. Horrors inflicted on non-combatants and the well publicized trading in conflict diamonds served to focus world attention on these two small countries sharing a common border. Both countries have experienced mixed success with outside military intervention for peace keeping and nation building purposes. What has happened is all the more distressing when one considers each countrys prospects at birth under the political and economic aegis of arguably two of the most powerful and enlightened countries of the time, Great Britain in the case of Sierra Leone and the United States in Liberia.     

BOOK REVIEWS

Book Reviewed in this article: Portable Utopia: Glasgow and the United States 1820–1920. Bernard Aspinwall. Studies in Russian Historical Geography. James H. Bater and R. A. French, eds. Water and Sanitation: Economic and Sociological Perspectives. Peter G. Bourne, ed. Green Politics. Fritjof Capra and Charlene Spretnak. The Southern Cone: Realities of the Authoritarian State. César N. Caviedes. Women in Third World Development. Sue Ellen Charlton. Land Management: New Directions. David Chiddick and Alan Millington, eds. Geography and Ethnic Pluralism. Colin Clarke, David Ley, Ceri Peach, eds. Geomorphological Hazards in Los Angeles. R. U. Cooke. Regional Impacts of United States-Mexico Economic Relations. Alfonso Corona and Lay James Gibson. eds. Patterns of Jobs and Geographic Mobility. Torvald Gerger. Cities and Sickness: Health Care in Urban America. Ann Lennarson Greer and Scott Greer, eds. Neighborhoods: Their Place in Urban Life. Howard W. Hallman. Development and the Rural-Urban Divide. John Harriss and Mick Moore, eds. Patterns of Undocumented Migration: Mexico and the United States. Richard C. Jones, ed. Central Place Theory. Leslie J. King. The Geography of Western Europe: A Socio-economic Survey. Paul L. Knox. Regions and Resources: Strategies for Development. David T. Krisge, Daniel A. Seiver, Oliver S. Goldsmith and Michael J. Scott. Geography of Crowding and Human Response. A Study of Ahmedabad City. K. M. Kulkarni. Haciendo Pueblo. The Development of a Guadalajaran Suburb. Kathleen Logan. The Imperial Lion: Human Dimensions of Wildlife Management in Central Africa. Stewart A. Marks. Water in the Hispanic Southwest: A Social and Legal History, 1550–1850. Michael C. Meyer. Imlil: A Moroccan Mountain Community in Change. James A. Miller. Tourism in Canada: Selected Issues and Options. Peter E. Murphy, ed. David Harvey's Geography. John L. Paterson. Raster Scanning, Processing and Plotting of Cartographic Documents. Donna J. Peuquet and A. Raymond Boyle. The USSR and the Muslim World: Issues in Domestic and Foreign Policy. Yaacov Ro'i, ed. Environmental Perception and Behavior: An Inventory and Prospect. Thomas F. Saarinen, David Seamon, and James L. Sell. Incised channels, Morphology, Dynamics, and Control. Stanley A. Schumm, Michael D. Harvey, and Chester C. Watson. The Gap Between Rich and Poor: Contending Perspectives on the Political Economy of Development. Mitchell A. Seligson, ed. Twentieth-Century Richmond. Planning, Politics and Race. Christopher Silver. Land Conservation and Development: Examples of Land-Use Planning Projects and Programs. F. R. Steiner and H. N. van Lier, eds. Biogeography: Recent Advances and Future Directions. J. A. Taylor, ed. Late Quaternary Environments of the Soviet Union. A. A. Velichko, ed. H. E. Wright, Jr. and C. W. Barnosky, eds.     

80 Ma以来海水Os同位素组成曲线的精细特征:中、西太平洋多金属结壳的记录

80 Ma以来的海水Os同位素标准曲线具有K/T（白垩纪/第三纪）界线低值、E/O（始新世/渐新世）界线低值和中新世“挠曲”3个特征形态，这可以解释为陨击事件或超基性岩风化事件造成的陆、幔源物质供给关系的变化。将海水Os同位素标准曲线与多金属结壳Os同位素组成曲线进行对比，根据形态和取值的贴合程度可以为结壳进行年代厘定。由于取样精度的限制和生长间断的广泛存在，仅以此3个特征比对曲线存在不确定性。本研究综合对比中、西太平洋6块结壳的Os同位素组成曲线，总结出了4种记录在结壳中的海水Os同位素曲线的特征规律：K/T界线之前的“早期异常（波动）”；E/O界线之后曲线上升过程中的“小停顿”；E/O界线之后曲线上升过程末尾的“异常偏高点”；“中新世‘挠曲’错后”至10 Ma左右。这些新的特征形态可作为年代控制点，使得结壳年代框架的厘定可以更准确可靠。这4种特征形态可以初步解释为地质历史时期海洋中、幔源物质的供应关系变化或是看作随着数据的积累而对标准曲线的细化和校正。     

鲁中南地区第四系河流砂金成矿特征的研究

本文研究了鲁中南地区河流砂金富集成矿特征及成矿时代.区内第四系出露时代齐全,成因类型繁多,岩性复杂.河流砂金矿层主要位于冲积或冲洪(洪冲)积物的底部,即古老变质岩系基岩面之上的含泥砂砾或砾砂等粗粒沉积物中.据资料和第四纪以来气候的冷暖变化,区内河流砂金的成矿时代可划分为中更新世(早期)、晚更新世(早期)和全新世(早、中期).     

Long-term change in the structure of a Posidonia oceanica landscape and its reference for a monitoring plan

Abstract On the basis of a detailed cartographic survey carried out by Side Scan Sonar and a towed underwater video camera during 2005, and from a series of historical maps (1959, 1980, 1990), an extensive regression of Posidonia oceanica (L.) Delile beds was evidenced for a vast area of the central Tyrrhenian Sea (Latium coast, Italy). The total loss of P. oceanica surface was assessed through GIS estimate. In 1959, the Posidonia beds extended over 7290 ha, while in the 2005 survey they had regressed to 2899 ha, a loss of about 60% of their coverage. Also the seagrass lower limit showed a general depth decrease in time. Total seagrass coverage loss and lower limit regression were not uniform along the whole investigated areas and three main sub-areas have been identified with different degrees of regression somehow related with coastal potential human-mediated impacts. From different coverage estimates of the present survey and of the previous maps, minimum sampling areas were calculated through bootstrapping simulation routines from small sampling areas (Landscape Units) to reach the nearest estimate of the observed condition in the different periods.     

ENSO as a natural experiment to understand environmental control of meiofaunal community structure

The sediments of the Bay of Concepción and the adjacent shelf underlie one of the most productive upwelling areas in the SE Pacific margin. Reports on factors controlling meiofaunal community structure in these kinds of organic‐rich and oxygen‐deficient habitats are scarce in the literature. In this study, five sites along a transect from the mid‐Bay of Concepción (27 m) to the outer shelf (120 m) were studied on fives dates (May, August, November 1997, and March and May 1998) in order to assess the dynamic relationships between sedimentary organic matter and metazoan meiofauna. The sampling period coincided with the 1997–1998 El Niño event. Sediment parameters investigated were the redox potential discontinuity depth, photosynthetic pigment concentrations (chlorophyll a and phaeopigments), organic carbon, nitrogen, total lipids, carbohydrates, and proteins. In general, lowest values of meiofauna abundance and biomass were found within the naturally eutrophic Bay of Concepción and towards the shelf break, while maximum values occurred at intermediate depths. During the whole period, the meiofaunal abundance was negatively correlated with the concentration of most of the biochemical components of organic matter, as well as with the sediment phaeopigment content. However, positive correlations were found with chlorophyll a derived indices and with bottom‐water oxygen content. Most of the sediment parameters displayed a seasonal cycle, but towards the beginning of 1998, an effect of the 1997–1998 El Niño was evident. Typical austral‐summer (i.e. oxygen‐deficient) conditions did not develop, and sedimentary parameters reflected a decreased input of phytodetritus. Along the transect, the magnitude of this effect on meiofauna varied among sites. An overall positive response, in terms of meiofaunal abundance was observed, probably due to the amelioration of low oxygen conditions in the sediment.     

线性工程控制测量中投影变形处理方法研究

对线性工程投影变形的特点以及解决方法进行了分析,并结合工程实例,通过对确定抵偿投影带和投影面的研究,获取了一种较为简便的控制长度变形的方法。在测区内采用一定限制的带宽和与设计高程相适应的投影面大地高,建立工程独立坐标系,即能有效地实现对两种长度变形的抵偿。实践证明,采用该方法能有效地解决线性工程控制测量长度投影变形问题。     

Landscape metrics for three-dimensional urban building pattern recognition

Understanding how landscape pattern determines population or ecosystem dynamics is crucial for managing our landscapes. Urban areas are becoming increasingly dominant social-ecological systems, so it is important to understand patterns of urbanization. Most studies of urban landscape pattern examine land-use maps in two dimensions because the acquisition of 3-dimensional information is difficult. We used Brista software based on Quickbird images and aerial photos to interpret the height of buildings, thus incorporating a 3-dimensional approach. We estimated the feasibility and accuracy of this approach. A total of 164,345 buildings in the Liaoning central urban agglomeration of China, which included seven cities, were measured. Twelve landscape metrics were proposed or chosen to describe the urban landscape patterns in 2- and 3-dimensional scales. The ecological and social meaning of landscape metrics were analyzed with multiple correlation analysis. The results showed that classification accuracy compared with field surveys was 87.6%, which means this method for interpreting building height was acceptable. The metrics effectively reflected the urban architecture in relation to number of buildings, area, height, 3-D shape and diversity aspects. We were able to describe the urban characteristics of each city with these metrics. The metrics also captured ecological and social meanings. The proposed landscape metrics provided a new method for urban landscape analysis in three dimensions.