Resonant and Secular Families of the Kuiper Belt

We review ongoing efforts to identify occupants of mean-motion resonances(MMRs) and collisional families in the Edgeworth–Kuiper belt. Directintegrations of trajectories of Kuiper belt objects (KBOs) reveal the 1:1(Trojan), 5:4, 4:3, 3:2 (Plutino), 5:3, 7:4, 9:5, 2:1 (Twotino), and 5:2 MMRsto be inhabited. Apart from the Trojan, resonant KBOs typically have largeorbital eccentricities and inclinations. The observed pattern of resonanceoccupation is consistent with resonant capture and adiabatic excitation bya migratory Neptune; however, the dynamically cold initial conditions priorto resonance sweeping that are typically assumed by migration simulationsare probably inadequate. Given the dynamically hot residents of the 5:2 MMRand the substantial inclinations observed in all exterior MMRs, a fraction ofthe primordial belt was likely dynamically pre-heated prior to resonancesweeping. A pre-heated population may have arisen as Neptune gravitationallyscattered objects into trans-Neptunian space. The spatial distribution of Twotinosoffers a unique diagnostic of Neptune's migration history. The Neptunian Trojanpopulation may rival the Jovian Trojan population, and the former's existence isargued to rule out violent orbital histories for Neptune. Finally, lowest-order seculartheory is applied to several hundred non-resonant KBOs with well-measured orbitsto update proposals of collisional families. No convincing family is detected.     

REGIONAL DEMOGRAPHIC STRUCTURE OF THE UNITED STATES

This paper analyzes the surprisingly great variation in demographic character across the states, utilizing data on fertility, mortality, age, sex, mobility, household character, abortion, race and ethnicity. A fairly simple regional pattern is revealed that is less related to levels of economic development than to long-standing historical cultural differences.     

Investigation of ion beam techniques for the analysis and exposure of particles encapsulated by silica aerogel: Applicability for Stardust

Abstract— In 2006, the Stardust spacecraft will return to Earth with cometary and perhaps interstellar dust particles embedded in silica aerogel collectors for analysis in terrestrial laboratories. These particles will be the first sample return from a solid planetary body since the Apollo missions. In preparation for the return, analogue particles were implanted into a keystone of silica aerogel that had been extracted from bulk silica aerogel using the optical technique described in Westphal et al. (2004). These particles were subsequently analyzed using analytical techniques associated with the use of a nuclear microprobe. The particles have been analyzed using: a) scanning transmission ion microscopy (STIM) that enables quantitative density imaging; b) proton elastic scattering analysis (PESA) and proton backscattering (PBS) for the detection of light elements including hydrogen; and c) proton‐induced X‐ray emission (PIXE) for elements with Z > 11. These analytical techniques have enabled us to quantify the composition of the encapsulated particles. A significant observation from the study is the variable column density of the silica aerogel. We also observed organic contamination within the silica aerogel. The implanted particles were then subjected to focused ion beam (FIB) milling using a 30 keV gallium ion beam to ablate silica aerogel in site‐specific areas to expose embedded particles. An ion polished flat surface of one of the particles was also prepared using the FIB. Here, we show that ion beam techniques have great potential in assisting with the analysis and exposure of Stardust particles.     

Longitudinal dispersion compensation for the Very Large Telescope Interferometer

The Very Large Telescope Interferometer [1,13] will be operated in air which will introduce small optical path fluctuations due to internal turbulence [4,6] and dispersion effects. Both may contribute to fringe contrast decrease. Longitudinal dispersion effects can be corrected by inserting an appropriate glass of variable thickness in one arm of the interferometer [3,5,11,12]. This paper presents a new method applied to VLTI in order to select the optimum glass, according to both the observing wavelength and the spectral bandpath, and to calculate its thickness. Results are presented in terms of improvement on the fringe contrast.     

Structural development along the Billefjorden Fault Zone in the area between Kjellströmdalen and Adventdalen/Sassendalen, central Spitsbergen

The Billefjorden Fault Zone represents a major lineament on Spitsbergen with a history of tectonic activity going back into the Devonian and possibly earlier. Recent structural, sedimcntological and stratigraphical investigations indicate that most of the stratigraphic thickness variations within the Mesozoic strata along the Billefjorden Fault Zone south of Isfjordcn are due to Tertiary compressional tectonics related to the transpressive Eocene West-Spitsbergen Orogeny. No convincing evidence of distinct Mesozoic extensional events, as suggested by previous workers, has been recognized. Tertiary compressional tectonics are characterized by a combined thin-skinned/thick-skinned structural style. Decollement zones arc recognized in the Triassic Sassendalen Group (tower Décollement Zone) and in the Jurassic/Cretaceous Janusfjellet Subgroup (Upper Décollement Zone). East-vergent folding and reverse faulting associated with these decollement' zones have resulted in the development of compressional structures, of which the major arc the Skolten and Tronfjellct Anticlines and the Advcntelva Duplex. Movements on one or more high angle east-dipping reverse faults in the pre-Mesozoic basement have resulted in the development of the Juvdalskampcn Monocline, and are responsible for out-of-sequence thrusting and thinning of the Mesozoic sequence across the Billefjorden Fault Zone. Preliminary shortening calculations indicate an eastward displacement of minimum 3-4 km, possibly as much as 10 km for the Lower Cretaceous and younger rocks across the Billefjorden Fault Zone.     

西藏结则茶卡湖岸沉积物中铀系年龄及意义

通过对藏北高原西北部结则茶卡湖泊及其沿岸地质地貌调查,发现其为一个富含硼、锂、钾、锶的封闭型盐湖,沿岸海拔4 850 m拔湖325 m有一条明显的高位湖岸线,该湖岸线到湖面之间有六级湖积阶地发育,六级以上阶地保存零星。沿湖岸不同高度上的湖积物U系年龄分别为(14.2±1.2)ka BP(T2)、(38.0±3.5)ka BP(T4)和(41.6±3.2)ka BP(T5)。湖面下降的幅度是藏北高原迄今所知最大。根据湖面平均下降速度推算高位湖岸线和高位湖积层的形成年龄在(120~90)ka BP,与东部的纳木错和西部的甜水海基本一致,说明藏北高原在晚更新世初期有一个明显的泛湖期。大约100 ka BP结则茶卡湖面开始下降,晚更新世以来湖泊演化是在封闭体系干旱环境下进行的,盐湖形成于14 ka BP左右,藏北高原在晚更新世以来气候变化可能为自西向东逐渐变为干寒。     

Method for evaluating the degrees of land use sustainability of mountainous county and its application in Yunnan Province,China

The evaluation of sustainable land use is the key issue in the field of studying the sustainable land utilization. In general analysis, the sustainable land use is evaluated respectively from its ecological sustainability, economic sustainability and social sustainability in China and other countries in recent years. Although this evaluation is an important work, it seems insufficient and hard to comprehensively reflect the whole degree of land use sustainability. Thus, to make up this deficiency, this paper brings forward the evaluation indexes, which make it possible to quantitatively reflect the whole degree of land use sustainability, namely, the concept of ＂degrees of overall land use sustainability＂ （Dos）, and research and measurement development of the method of and calculation in Dos. Taking the evaluation of the degree of land use sustainability in county regions of Yunnan Province as the actual example for analysis, results are basically as follows：
1） The degree of land use sustainability （Dos） is the ration index to organically and systematically integrate the degree of ecological friendliness （DeF）, the degree of economic viability （Dev） and the degree of social acceptability （Dsa）, able to comprehensively reflect the whole sustainability degree of regional land use
2） Based on the value of Dos, the grading system and standard for the sustainability of land use may be established and totally divided into five grades, namely, the high-degree sustainability, middle-degree sustainability, low-degree sustainability, conditional sustainability and non-sustainability. Meanwhile, the standard for distinguishing sustainability grades has also been confirmed so as to determine the nature of sustainability degrees in different grades. This makes the possibility for the combination of nature determination with ration in research result and provides with the scientific guideline and decision-making gist for better implementation of sustainable land use strategy.
3） The pract     

Neutron capture measurements on radioactive93Zr

Neutron capture measurements made on a sample of fission-product zirconium containing 20%⁹³Zr(t _1/2=1.5×10⁶a) at the Oak Ridge Electron Linear Accelerator time-of-flight facility resulted in the identification of 138 resonance peaks for the⁹³Zr isotope at neutron energies up to 21.5 keV. Average capture cross sections from 20 to 300 keV were derived by subtracting neutron capture yields of the stable zirconium isotopes^{90, 91, 92, 94, 96}Zr and additional backgrounds. The average cross sections found were significantly less than those of JENDL-1. While generally 30% higher than those of ENDF/B —V below 60 keV, the binned data overlapped the smooth ENDF/B —V curve. The average for a Maxwellian neutron spectrum withkT=30 keV is (95±10) mb and the resonance contribution to the capture resonance integral is (15.0±0.5)b.Research sponsored by the U.S. Department of Energy, Office of Basic Energy Sciences, under contract DE-AC05-840R21400 with the Martin Marietta Energy Systems, Inc.