Geology of the Caloris basin, Mercury: a view from MESSENGER

The Caloris basin, the youngest known large impact basin on Mercury, is revealed in MESSENGER images to be modified by volcanism and deformation in a manner distinct from that of lunar impact basins. The morphology and spatial distribution of basin materials themselves closely match lunar counterparts. Evidence for a volcanic origin of the basin's interior plains includes embayed craters on the basin floor and diffuse deposits surrounding rimless depressions interpreted to be of pyroclastic origin. Unlike lunar maria, the volcanic plains in Caloris are higher in albedo than surrounding basin materials and lack spectral evidence for ferrous iron-bearing silicates. Tectonic landforms, contractional wrinkle ridges and extensional troughs, have distributions and age relations different from their counterparts in and around lunar basins, indicating a different stress history.     

中国南方高保护价值森林判定研究

高保护价值森林的判定标准是高保护价值森林研究的基础,对高保护价值森林的研究可以将人们对森林的关注重点从传统的森林经营、森林采伐等方面转移到森林所具有的生态、社会、文化等特殊价值上来。目前在高保护价值森林判定过程中存在最主要的问题是判定标准不统一,本研究拟在现有的6大判定标准的框架内,结合研究区的实际情况建立了各判定标准的评判指标体系,提出了适合我国南方森林特点的高保护价值森林判定标准,并对福建永安林业(集团)有限公司经营区进行高保护价值森林判定。结果表明:研究区内森林存在高保护价值1、3、4、5,各高保护价值森林面积分别为4 742、656、14 641、3 828 hm2。     

Energy choices for the next 15 years: a view from europe

A European perception of the world energy situation and its likely evolution during the next two decades is presented. French energy policy is then discussed as a possible set of consistent choices that can be made to deal with the energy situation in a regional context for the next 15 years.     

Long waves in the eastern equatorial pacific ocean: a view from a geostationary satellite

During 1975, westward-moving long waves with a period of about 25 days and a wavelength of 1000 kilometers were observed at a sea surface temperature front in the equatorial Pacific on infrared images obtained by a geostationary environmental satellite system. The absence of these waves during 1976, and the above-average equatorial sea surface temperatures during 1976, may be related to a decrease in the southeasterly trade winds during that year.     

Mars' south polar Ar enhancement: a tracer for south polar seasonal meridional mixing

The gamma ray spectrometer on the Mars Odyssey spacecraft measured an enhancement of atmospheric argon over southern high latitudes during autumn followed by dissipation during winter and spring. Argon does not freeze at temperatures normal for southern winter (approximately 145 kelvin) and is left in the atmosphere, enriched relative to carbon dioxide (CO2), as the southern seasonal cap of CO2 frost accumulates. Calculations of seasonal transport of argon into and out of southern high latitudes point to meridional (north-south) mixing throughout southern winter and spring.     

The subduction zone flow field from seismic anisotropy: a global view

Although the morphologies of subducting slabs have been relatively well characterized, the character of the mantle flow field that accompanies subduction remains poorly understood. To analyze this pattern of flow, we compiled observations of seismic anisotropy, as manifested by shear wave splitting. Data from 13 subduction zones reveal systematic variations in both mantle-wedge and subslab anisotropy with the magnitude of trench migration velocity |V(t)|. These variations can be explained by flow along the strike of the trench induced by trench motion. This flow dominates beneath the slab, where its magnitude scales with |V(t)|. In the mantle wedge, this flow interacts with classical corner flow produced by the convergence velocity V(c); their relative influence is governed by the relative magnitude of |V(t)| and V(c).     

Deskilling, agrodiversity, and the seed trade: a view from contemporary British allotments

Over the last half-century, quality control standards have had the perverse effect of restricting the circulation of non-commercially bred vegetable cultivars in Britain. Recent European and British legislation attempts to compensate for this loss of agrodiversity by relaxing genetic purity standards and the cost of seed marketing for designated “Amateur” and “Conservation” varieties. Drawing on fieldwork conducted at a British allotment site, this article cautions against bringing genetically heterogeneous cultivars into the commercial sphere. Such a move may intensify the horticultural “deskilling” of British allotment gardeners, who have come to rely on commercial seed catalogs as sources of germplasm and knowledge. Horticultural deskilling also entails the delegation of seed selection activities to professional breeders and the potential loss of agrodiversity. The activities of dedicated seed savers who save and circulate the seed of genetically heterogeneous “heritage” varieties, in a manner similar to the management of landraces in the global South, may provide a better model for attempts to safeguard vegetable diversity in the global North.     

Office of management and budget: the view from the executive office

The federal budget will make its annual appearance at the end of the month under the seal of the Office of Management and Budget, a highly influential but reticent agency cloistered in the Executive Office of the President. This first of three articles on OMB discusses the development of the budget agency since World War II and looks at the evolution of the science budget from the OMB perspective.