Radar detection of the nucleus and coma of comet hyakutake

Radar observations of comet Hyakutake (C/1996 B2) made at the Goldstone Deep Space Communications Complex in California have detected echoes from the nucleus and from large grains in the inner coma. The nucleus of this bright comet was estimated to be only 2 to 3 kilometers in diameter. Models of the coma echo indicate backscatter from porous, centimeter-size grains ejected anisotropically at velocities of tens of meters per second. The radar observations suggest that a comet's activity may be a poor indicator of its size and provide evidence that large grains constitute an important component of the mass loss from a typical active comet.     

Accelerated human population growth at protected area edges

Protected areas (PAs) have long been criticized as creations of and for an elite few, where associated costs, but few benefits, are borne by marginalized rural communities. Contrary to predictions of this argument, we found that average human population growth rates on the borders of 306 PAs in 45 countries in Africa and Latin America were nearly double average rural growth, suggesting that PAs attract, rather than repel, human settlement. Higher population growth on PA edges is evident across ecoregions, countries, and continents and is correlated positively with international donor investment in national conservation programs and an index of park-related funding. These findings provide insight on the value of PAs for local people, but also highlight a looming threat to PA effectiveness and biodiversity conservation.     

Cassini magnetometer observations during Saturn orbit insertion

Cassini's successful orbit insertion has provided the first examination of Saturn's magnetosphere in 23 years, revealing a dynamic plasma and magnetic environment on short and long time scales. There has been no noticeable change in the internal magnetic field, either in its strength or its near-alignment with the rotation axis. However, the external magnetic field is different compared with past spacecraft observations. The current sheet within the magnetosphere is thinner and more extended, and we observed small diamagnetic cavities and ion cyclotron waves of types that were not reported before.     

HIV vaccine research: the way forward

The need to broaden research directed at answering fundamental questions in HIV vaccine discovery through laboratory, nonhuman primate (NHP), and clinical research has recently been emphasized. In addition, the importance of attracting and retaining young researchers, developing better NHP models, and more closely linking NHP and clinical research is being stressed. In an era of a level budget for biomedical research at the U.S. National Institutes of Health (NIH), HIV/AIDS vaccine research efforts will need to be carefully prioritized such that resources to energize HIV vaccine discovery can be identified. This article summarizes progress and challenges in HIV vaccine research, the priorities arising from a recent summit at NIAID, and the actions needed, some already under way, to address those priorities.     

Integration of engineering,institutional and social requirements into rehabilitation design. A case study from Nepal

The paper describes the engineering approach which was adopted by irrigation engineers in collaboration with sociologists to address the technical, institutional and social constraints found in a study for rehabilitation of a Government run irrigation scheme in Nepal. Designs were evolved to provide a system which was easy to operate, made abuse of the system easy to identify, and encouraged farmer cooperation and the formation of water user groups.     

Aquatic Hazard Assessment of a Contaminated Surficial Aquifer Discharge into the Bush River,Maryland (U.S.A.)

An aquatic hazard assessment of contaminatedgroundwater in a surficial aquifer was conducted at Beach Pointwhich is located in the Edgewood Area of the U.S. Army Garrison,Aberdeen Proving Ground, Maryland. Toxicity was detected atvarious groundwater concentrations by seven of 10 toxicity testsystems exposed to a mixture of heavy metals and chlorinatedaliphatic hydrocarbons. When estimated maximum acceptabletoxicant concentrations (MATC) were established, the data foralgae, invertebrates, and fish suggested that the groundwaterwould not be harmful at a concentration of 10% groundwater byvolume. Likewise, no genotoxicity (Ames and SEC assays),development toxicity (FETAX), or chronic histopathology (9-monthfish test) occurred at 10% groundwater by volume.Near-field (ULINE model) and far-field (dye-tracer model)screening level dilution models were run to estimate the dilutionof the groundwater discharge plume from Beach Point into the BushRiver. The groundwater was considered to be a potentiallyexcessive hazardous material to the biota in the Bush River whena number of conservative assumptions regarding contaminantdistribution and discharge rate of the aquifer were used in thehazard assessment. By modeling the groundwater emanating fromBeach Point as the dilution of a discharge from a line diffuser,the potential water quality impacts were judged to be minimal ifState of Maryland surface water discharge criteria for a mixingzone were used for the discharge of groundwater to the Bush River.     

Response of Tribolium castaneum (Coleoptera, Tenebrionidae) to Salpichroa origanifolia Withanolides.

Biological effects on Tribolium castaneum larvae were evaluated for three withanolides isolated from Salpichroa origanifolia (Solanaceae), (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-26-hydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide A, 1), (20S,22R,24S,25S,26R)-22,26:24,25-diepoxy-5alpha,6beta,26-trihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide C, 2), and (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-15,26-dihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide G, 3), and for several chemically modified analogues. The compounds were incorporated into the larval diet at concentrations of 500 and 2000 ppm. Salpichrolide C (2) produced a significant delay in the development of neonate larvae to adults at the highest concentration (2000 ppm); development delays and lethal effects were produced by salpichrolides A (1) and G (3) at both concentrations assayed. The size of surviving adults was used as a criterion for assessing feedant deterrent effects; the results suggest that these compounds act as feeding inhibitors. Influence of chemical modifications in development delay was analyzed.     

Recurrent phenotypic selection for forage yield in rye

Summary Cultivars of Cucurbita pepo and other Cucurbita species were characterized by RFLP analysis using different fragments of the ribosomal intergenic spacer (IGS) of Cucurbita pepo as hybridization probes. Several cultivars could be distinguished by a specific rDNA restriction pattern, whereas some cultivars showed an identical RFLP pattern suggesting a closer relationship. Other species of the genus Cucurbita exhibited strong cross-reaction with the C. pepo spacer probes, in contrast to DNA of Cucumis species which did not cross-hybridize.Abbreviations IGS intergenic spacer - ITS internal transcribed spacer - kbp kilo base pairs - rDNA ribosomal DNA - RFLP restriction fragment length polymorphism - rRNA ribosomal RNA