引力向量与引力张量的三维笛卡儿坐标表示式

导出了引力向量和引力张量球谐函数展开式的三维笛卡儿坐标表示公式 ,并给出了该表示式在两极和赤道的简化形式 .引力向量和引力张量的三维笛卡儿坐标表示式在形式上比球坐标表示式简单 ,且便于表示卫星的三维笛卡儿坐标系摄动量与位系数的关系     

Monitoring temporal change in riparian vegetation of Great Basin National Park

Disturbance in riparian areas of semiarid ecosystems involves complex interactions of pulsed hydrologic flows, herbivory, fire, climatic effects, and anthropogenic influences. We resampled riparian vegetation within ten 10-m × 100-m plots that were initially sampled in 1992 in 4 watersheds of the Snake Range, east central Nevada. Our finding of significantly lower coverage of grasses, forbs, and shrubs within plots in 2001 compared with 1992 was not consistent with the management decision to remove livestock grazing from the watersheds in 1999. Change over time in cover of life-forms or bare ground was not predicted by scat counts within plots in 2001. Cover results were also not well explained by variability between the 2 sampling periods in either density of native herbivores or annual precipitation. In contrast, Engelmann spruce ( Picea engelmannii ) exhibited reduced abundance at all but the highest-elevation plot in which it occurred in 1992, and the magnitude of change in abundance was strongly predicted by plot elevation. Abundance of white fir ( Abies concolor ) individuals increased while aspen ( Populus tremuloides ) individuals decreased at 4 of 5 sites where they were sympatric, and changes in abundance in the 2 species were negatively correlated across those sites. Utility of monitoring data to detect change over time and contribute to adaptive management will vary with sample size, observer bias, use of repeatable or published methods, and precision of measurements, among other factors.     

Necrophagous or predators? The role of Pheidole radoszkowskii Mayr (Hymenoptera: Formicidae) on Rattus norvegicus (Berkenhout) carcasses (Rodentia: Muridae)

This study aimed to identify the feeding habit of Pheidole radoszkowskii Mayr on Rattus norvegicus (Berkenhout) carcasses, as well as whether its presence limits the occurrence of flies. Pheidole radoszkowskii exhibited more necrophagous than predatory behaviour. Its abundance was inversely proportional to that of flies, confirming that this ant species may cause lesions in carcasses and its presence limits the occurrence of flies. This work clarifies the behaviour of an ant species often encountered on carcasses.     

Arizona distribution of three Sonoran Desert anurans: Bufo retiformis, Gastrophryne olivacea , and Pternohyla fodiens

We surveyed historic collecting localities in south central Arizona during July, August, and September 1993-94 to determine the presence of 3 little-known Sonoran Desert anurans, Bufo retiformis, Gastrophryne olivacea, and Pternohyla fodiens . All 3 species were present at most historic localities visited under appropriate conditions (following rainfall in July and August). Pternohyla fodiens was restricted to San Simon Wash and associated tributaries in south central Pima County. Gastrophryne olivacea ranged from Vekol Valley in extreme southern Maricopa County south to the Mexican border, and southeast near Tucson and Nogales in Pima and Santa Cruz counties. Bufo retiformis occurred over the widest area, from southern Rainbow Valley in Maricopa County southwest to the vicinity of Organ Pipe Cactus National Monument, and southeast to the vicinity of Tucson and Sasabe in Pima County.     

Sustainability Transitions and the Nature of Technology

For more than 20?years, sustainable development has been advocated as a way of tackling growing global environmental and social problems. The sustainable development discourse has always had a strong technological component and the literature boasts an enormous amount of debate on which technologies should be developed and employed and how this can most efficiently be done. The mainstream discourse in sustainable development argues for an eco-efficiency approach in which a technology push strategy boosts efficiency levels by a factor 10 and more in industrialised and developing countries. A minority argues for a socio-cultural lifestyle switch, relying on new values, quality of life, sufficiency and redistribution strategies, with calls for appropriate and soft technologies. It is remarkable, however, that the articles, books and policy debates on sustainability seldom explicitly draw in a discussion of the nature of technology, how technology influences and is influenced by society, and what this implies for sustainable development. The mainstream interprets technology as neutral and instrumental: technology is no more than an instrument to reach a goal; it cannot be judged on its intrinsic characteristics, only on its use. The alternative view often builds on an autonomous and substantive interpretation of technology: technology is an autonomous, almost uncontrollable power that fundamentally reshapes our culture. A more balanced approach seems to be growing in the research on socio-technical sustainability transitions where the focus shifts to the co-evolution of technology and society, and to the networks, seamless webs and complex multi-actor processes that may carry a sustainability transition forward. This approach builds on insights from recent traditions in the philosophy and sociology of technology, in particular the social construction of technology (SCOT) and actor-network theory (ANT). While this provides for a better understanding of the nature and potential role of technology in sustainability policies, it remains to be seen whether it will actually influence the choice between technologies. This article investigates the different conceptualisations of technology in the sustainability debate. It first distinguishes between different approaches of sustainability and how these are related to differing views on technology. It then moves on to how the socio-technical transitions research incorporates insights from contemporary philosophy and sociology of technology. It reflects on the potential of transitions research to give guidance in technology choices, suggesting that the transition approach might be strengthened by drawing in insights from critical theory of technology and by taking a more political stance in defining sustainable development.     

The Sagittarius impact as an architect of spirality and outer rings in the Milky Way

Like many galaxies of its size, the Milky Way is a disk with prominent spiral arms rooted in a central bar, although our knowledge of its structure and origin is incomplete. Traditional attempts to understand our Galaxy's morphology assume that it has been unperturbed by major external forces. Here we report simulations of the response of the Milky Way to the infall of the Sagittarius dwarf galaxy (Sgr), which results in the formation of spiral arms, influences the central bar and produces a flared outer disk. Two ring-like wrappings emerge towards the Galactic anti-Centre in our model that are reminiscent of the low-latitude arcs observed in the same area of the Milky Way. Previous models have focused on Sgr itself to reproduce the dwarf's orbital history and place associated constraints on the shape of the Milky Way gravitational potential, treating the Sgr impact event as a trivial influence on the Galactic disk. Our results show that the Milky Way's morphology is not purely secular in origin and that low-mass minor mergers predicted to be common throughout the Universe probably have a similarly important role in shaping galactic structure.     

Transiting circumbinary planets Kepler-34 b and Kepler-35 b

Most Sun-like stars in the Galaxy reside in gravitationally bound pairs of stars (binaries). Although long anticipated, the existence of a 'circumbinary planet' orbiting such a pair of normal stars was not definitively established until the discovery of the planet transiting (that is, passing in front of) Kepler-16. Questions remained, however, about the prevalence of circumbinary planets and their range of orbital and physical properties. Here we report two additional transiting circumbinary planets: Kepler-34 (AB)b and Kepler-35 (AB)b, referred to here as Kepler-34 b and Kepler-35 b, respectively. Each is a low-density gas-giant planet on an orbit closely aligned with that of its parent stars. Kepler-34 b orbits two Sun-like stars every 289?days, whereas Kepler-35 b orbits a pair of smaller stars (89% and 81% of the Sun's mass) every 131?days. The planets experience large multi-periodic variations in incident stellar radiation arising from the orbital motion of the stars. The observed rate of circumbinary planets in our sample implies that more than ～1% of close binary stars have giant planets in nearly coplanar orbits, yielding a Galactic population of at least several million.     

Which Wisdom Can Change the World?

The thoughts that Michel Puech formulates on wisdom, technology and the art of living are timely at a moment when social, ecological and economic problems are pressing upon our societies and the speed of technological development seems to overwhelm our ability to integrate and adapt new technologies in our lives and societies. However, he restricts his concept of wisdom too much to a personal endeavor and overestimates the relevance of non-confrontation. I argue that his project can only be of value when it is embedded in a broader societal and political strategy for change.     

Introduction. Meaningfulness,Volunteers, Citizenship

This introductory article starts by describing the genesis of this special issue and the interconnection of its topics. The editors offer a variety of reading entries into the key-note articles and responses. The article reconstructs the research interests underpinning the idea of integrating meaningfulness, volunteers and citizenship. It highlights the explicit interdisciplinary design of the special issue, and shows how the key-note authors, and their respondents, weave connections between meaningfulness, volunteering and citizenship. And, finally, the editors bring the background understandings of the key-note papers to the foreground, and reconstruct a non-intentional meta-level discussion on two fundamental concepts and their interplay: self and world.     

Examining ecological consequences of feral horse grazing using exclosures

Although feral horses have inhabited western North America since the end of the 16th century, relatively little synecological research has been conducted to quantitatively characterize how they interact with ecosystem components. Because feral horses exhibit watering behavior markedly different from that of domestic cattle, it is particularly important to evaluate response of ecosystem elements near water sources to horse use. To assess this response, we performed live-trapping of small mammals and 2-tiered vegetative sampling in 2 mountain ranges in central Nevada in the interior Great Basin, USA. At low elevations, plots around horse-excluded springs exhibited notably greater plant species richness, percent cover, and abundance of grasses and shrubs, as well as more small mammal burrow entrances than plots at horse-grazed springs. At high elevations, meadows protected from grazing exhibited maximum vegetation heights 2.8 times greater than vegetation grazed by horses only and 4.5 times greater than vegetation grazed by horses and cattle. Species richness in quadrats was most different between the horse-and-cattle-grazed meadow and its ungrazed counterpart, suggesting the possibility of synergistic effects of horse and cattle grazing in the same location. This study, the first in the Great Basin to investigate quantitatively ecosystem consequences of feral horse use with exclosures, represents a preliminary step in identifying factors that determine the magnitude of horse grazing impacts.