Forced resonant migration of Pluto's outer satellites by Charon

Two small moons of Pluto have been discovered in low-eccentricity orbits exterior to Pluto's large satellite, Charon. All three satellite orbits are nearly coplanar, implying a common origin. It has been argued that Charon formed as a result of a giant impact with primordial Pluto. The orbital periods of the two new moons are nearly integer multiples of Charon's period, suggesting that they were driven outward by resonant interactions with Charon during its tidal orbital expansion. This could have been accomplished if Charon's orbit was eccentric during most of this orbital evolution, with the small moons originating as debris from the collision that produced Charon.     

Cassini Imaging Science: initial results on Saturn's rings and small satellites

Images acquired of Saturn's rings and small moons by the Cassini Imaging Science Subsystem (ISS) during the first 9 months of Cassini operations at Saturn have produced many new findings. These include new saturnian moons; refined orbits of new and previously known moons; narrow diffuse rings in the F-ring region and embedded in gaps within the main rings; exceptionally fine-scale ring structure in moderate- to high-optical depth regions; new estimates for the masses of ring-region moons, as well as ring particle properties in the Cassini division, derived from the analysis of linear density waves; ring particle albedos in select ring regions; and never-before-seen phenomena within the rings.     

PLANETARY SCIENCE: Saturn Wins Satellite Title With New Moons

This week an international team of astronomers announced the discovery of four new moons of Saturn, restoring the ringed planet to its status as commander of the largest retinue of satellites in the solar system. Their appearance should help researchers understand not just how the new moons were formed but also how the giant planets themselves came to be.     

The second ring-moon system of Uranus: discovery and dynamics

Deep exposures of Uranus taken with the Hubble Space Telescope reveal two small moons and two faint rings. All of them orbit outside of Uranus's previously known (main) ring system but are interior to the large, classical moons. The outer new moon, U XXVI Mab, orbits at roughly twice the radius of the main rings and shares its orbit with a dust ring. The second moon, U XXVII Cupid, orbits just interior to the satellite Belinda. A second ring falls between the orbits of Portia and Rosalind, in a region with no known source bodies. Collectively, these constitute a densely packed, rapidly varying, and possibly unstable dynamical system.     

白三叶草坪春季昆虫群落构成的研究

对白三叶(Trifolumrepens.L.)草坪春季昆虫群落系统进行了调查及分析,结果表明:白三叶草坪春季昆虫群落由9目28种组成。其中蚜虫、叶螨是春季昆虫群落的优势种。在白三叶草坪昆虫群落演替中,通过对N,S,T,H四个指数的分析,表明4月份昆虫群落比较旺盛,但5月份昆虫群落结构更稳定协调。这些研究为白三叶草坪害虫综合治理提供依据。     

Clump detections and limits on moons in Jupiter's ring system

The dusty jovian ring system must be replenished continuously from embedded source bodies. The New Horizons spacecraft has performed a comprehensive search for kilometer-sized moons within the system, which might have revealed the larger members of this population. No new moons were found, however, indicating a sharp cutoff in the population of jovian bodies smaller than 8-kilometer-radius Adrastea. However, the search revealed two families of clumps in the main ring: one close pair and one cluster of three to five. All orbit within a brighter ringlet just interior to Adrastea. Their properties are very different from those of the few other clumpy rings known; the origin and nonrandom distribution of these features remain unexplained, but resonant confinement by Metis may play a role.     

Total luminous flux: a possible response determinant for the normal monkey

Thirteen normal monkeys (Macaca mulatta) trained to discriminate between transilluminated figures of equal area and different luminance, and consequently different luminous flux, made similar numbers of errors during training on a new problem with the same luminance values but with targets equated for luminous flux. These findings together with results of "critical trials" suggest that the significant cue in the original problem was luminous flux. This behavior is strikingly similar to what has been reported for the monkey following exclusion of the geniculostriate system.     

吊扇在仔鸡舍中的运用及其气流特性

为测定吊扇对气流的影响,一系列的实验已经完成。吊扇进行单个或成组测试。单个测试的结果与其他早些时候的研究结果完全吻合。并且业已证明,由吊扇听产生的气流为一墙壁射流,有关该射流参数的公式已经导出。我们将进一步作实地测试,以确证吊扇对仔鸡的影响。经初步观察指出,仔鸡有受惊反应并迁移它们的位置。美国农业工程师协会应该考虑制定吊扇的试验规范。     

大豆种子超弱发光的研究——Ⅱ.光子辐射强度与种子活力的相关性

大豆种子经老化处理后,以干种子、干粉和萌发24h的种子为材料进行超弱发光强度的测定。结果表明,种子发芽率和活力指数与发光强度呈高度负相关,相关系数则在-0.888～-0.965之间,相关性干粉>干种子>萌发种子。利用超弱发光强度估价种子活力是一种快速、简便、不破坏种子的新方法。     

Grain size-sensitive creep in ice II

Rheological experiments on fine-grained water ice II at low strain rates reveal a creep mechanism that dominates at conditions of low stress. Using cryogenic scanning electron microscopy, we observed that a change in stress exponent from 5 to 2.5 correlates strongly with a decrease in grain size from about 40 to 6 micrometers. The grain size-sensitive creep of ice II demonstrated here plausibly dominates plastic strain at the low-stress conditions in the interior of medium- to large-sized icy moons of the outer solar system.     

Disappearance of luminous designs

When a subject fixates on a luminous design under conditions of low illumination, he experiences a fragmenting disappearance of the figure. This fragmentation occurs in meaningful units and is comparable to the disappearance of images stabilized on the retina. The luminous paint technique offers a new and simple approach to the study of visual perception.     

土地征收最高限价与耕地保护的矛盾关系分析

我国提出"坚持最严格的耕地保护制度",实施了一系列积极的耕地保护政策,而实施结果与预期目标存在较大差距。土地征收过程中形成的最高限价是其中一个不容忽视的因素。文章利用经济学知识分析了最高限价与耕地保护间存在的矛盾关系,并由此提出改革征地补偿标准、明晰土地产权、规范政府和用地单位行为、建立失地农民安置机制等缓解措施。     

Mass spawning in tropical reef corals

Synchronous multispecific spawning by a total of 32 coral species occurred a few nights after late spring full moons in 1981 and 1982 at three locations on the Great Barrier Reef, Australia. The data invalidate the generalization that most corals have internally fertilized, brooded planula larvae. In every species observed, gametes were released; external fertilization and development then followed. The developmental rates of externally fertilized eggs and longevities of planulae indicate that planulae may be dispersed between reefs.     

一种新型生物能源发光苔藓的研究

利用转基因技术将萤火虫的荧光基因和苔藓融合,产生一种新的生物替代能源,其原理是通过荧光现象和光合作用的协同,实现低消耗的能量循环,成为一个自给自足的供光体系。作为地下的供光系统,苔藓的某些生活特性可以有效地解决矿难的发生。其衍生品光苔灯,可以应用到公共环境照明中。以光苔能源改善社会的能源结构,从而达到可持续发展的目的,实现绿色能源的广泛普及。     

Enceladus: cosmic gymnast, volatile miniworld

The exploration of Saturn by the Cassini/Huygens mission has yielded a rich collection of data about the planet and its rings and moons, in particular its small satellite Enceladus and giant satellite Titan. Once believed too small to be active, Enceladus has been found to be one of the most geologically dynamic objects in the solar system. Among the surprises are a watery, gaseous plume; a south polar hot spot; and a surface marked by deep canyons and thick flows.     

电磁场对绿豆萌芽的超弱发光和腺苷三磷酸的影响

本文报道了１０００ｖ／ｃｍ，５００ｖ／ｃｍ静电场和０．１Ｔ，０．２Ｔ恒磁场对绿豆萌芽的超弱发光强度以及腺苷三磷酸含量的影响及其机理。     

Pancam multispectral imaging results from the Spirit Rover at Gusev Crater

Panoramic Camera images at Gusev crater reveal a rock-strewn surface interspersed with high- to moderate-albedo fine-grained deposits occurring in part as drifts or in small circular swales or hollows. Optically thick coatings of fine-grained ferric iron-rich dust dominate most bright soil and rock surfaces. Spectra of some darker rock surfaces and rock regions exposed by brushing or grinding show near-infrared spectral signatures consistent with the presence of mafic silicates such as pyroxene or olivine. Atmospheric observations show a steady decline in dust opacity during the mission, and astronomical observations captured solar transits by the martian moons, Phobos and Deimos, as well as a view of Earth from the martian surface.     

The most luminous stars

Stars with individual luminosities more than a million times that of the sun are now being studied in a variety of contexts. Observational and theoretical ideas about the most luminous stars have changed greatly in the past few years. They can be observed spectroscopically even in nearby galaxies. They are not very stable; some have had violent outbursts in which large amounts of mass were lost. Because of their instabilities, these stars do not evolve to become red superglants as less luminous stars do. Theoretical scenarios for the evolution of these most massive stars depend on the effects of turbulence and mixing combined with high radition densities.     

喷淋式MOCVD反应器的传质分析及结构设计

对喷淋式MOCVD反应器中的传质过程进行了数理分析,并提出了该类型反应器的结构设计原则.数理分析显示,基片上方各点的轴向速度仅是垂直距离的函数,与径向距离无关;顶壁高度对反应室内的传质有重要影响.设计喷淋式反应器结构时,应重点考虑顶壁高度和反应室半径的选取、基片加热方式以及喷淋头结构的柔性设计.