Correlation of the Meishucunian Stage in South Asia

The determination of boundary points and their correlation are prerequisites for defining the PrecambrianCambrian boundary and the intercontinental correlation. A large number of good Precambrian-Cambrian boundary sections in South Asia not only possess the conditions for selection of a boundary stratotype, but also provide the basis for the long-distance correlation of those boundary sections.Through a detailed study of the latest data obtained from the typical sections in South China, the Lesser Himalaya Mountains and the Alborz Mountains. the locations of boundary points have been defined, and a correlation scheme is proposed, which contributes to the solution of the problem of worldwide correlation of boundary sections.     

Correlation of trace elements with hydrocarbon microseepage

Direct correlation have been observed between certain trace element and hydrocarbon anomalies in the near subsurface soils of Vindhyan basin, India. This relationship with hydrocarbon is very useful in hydrocarbon exploration. 52 soil samples from Vindhyan basin were collected from a depth of 2.5m. All the soil samples were analyzed for light hydrocarbon, isotope and trace element concentrations. The adsorbed light gaseous hydrocarbon analyses show the presence of methane (8–328 ppb), ethane (0–27 ppb) and propane (0–11 ppb) respectively and these values indicate the presence of hydrocarbon micro-seepage in the study area. The carbon isotopic values determined for methane and ethane for these soil samples are (?26.41 to ?47.70 ‰ PDB) and (?20.07 to ?35.30 ‰ PDB) respectively and they are thermogenic in nature. The trace element concentrations of nickel (33–220 ppm), vanadium (72–226 ppm), copper (20–131 ppm), chromium (94–205 ppm), zinc (66–561 ppm) and cobalt (9–39 ppm) have higher than the normal concentrations in soils. Trace element concentrations are used to plot with the data obtained from light gaseous hydrocarbon concentrations and carbon isotopic values of soil samples of the Vindhyan basin. Trace element anomalies have been observed around the hydrocarbon anomalies in the study area.     

Old, Low-Mass, Metal-Rich (SMR) Stars

The authors of this paper try to disentangle the many problems arisen from a new enlarged sample of nearby low-mass,metal-rich-stars. These stars have reliable absolute magnitudes, deduced from Hipparcos parallaxes, precise bolometric corrections, effective temperatures and metal abundances from high resolution detailed spectroscopic analyses. Their ages have been derived from a grid of isochrones calculated with up to date physics. The main goal of this paper is to determine the ages of the slightly evolved SMR stars. Among those with well determinated ages about 80% of them have intermediate ages of (2 to 5 Gyr), but only 20% have ages of 8 Gyr or more. Nevertheless, the existence of very old metal-rich stars is confirmed. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Holocene record of climate change,fire ecology and human activity from montane Flat Top Bog,Maui

A sediment core from a high-elevation bog on Maui in the Hawaiian Islands contains evidence for drier conditions between 9.4–5.8 kyr BP, followed by a wetter interval between 5.8–2.2 kyr BP, and a variable late Holocene. These precipitation changes may be a reflection of vertical displacements of the upper boundary of the mid-Pacific Trade Wind Inversion (TWI) cloud layer. Fires, probably volcanically ignited, occurred in the forests prior to human arrival. Polynesian activity in this high-elevation, remote site was apparently limited, with no pollen, charcoal, or sedimentological evidence for local anthropogenic disturbance. After European contact, grass fires increased and introduced plant species invaded the site. Values for Cd, Cu, Pb, and Zn in sediments throughout the Holocene indicate low trace-metal deposition from atmospheric particulates at the site, even in the twentieth century.This paper is one of a series of papers guest edited by Dr. Mark Brenner on tropical paleolimnology     

Strontium and oxygen isotope evidence relating to the petrogenesis of the Kangerdlugssuaq alkaline instrusion,East Greenland

The Kangerdlugssuaq intrusion, East Greenland, consists of quartzsyenites, syenites, pulaskites and foyaites. The age and petrogenesis of the intrusion has been investigated by strontium and oxygen isotope analyses of the major rock types (and some separated minerals) and the surrounding country rocks. Crystallization and rapid cooling of the intrusion close to 50 m.y. ago is indicated by concordance of an Rb-Sr mineral isochron (49.9±1.0 m.y.) and an Rb-Sr whole-rock isochron (50.0±1.9 m.y.) with previously published mineral dates. The feldspathoid-bearing rocks of the intrusion, which were the last to crystallize, have uniformly depleted oxygen (¹⁸O = +3.9, SMOW) and homogeneous initial ⁸⁷Sr/⁸⁶Sr ratios (0.70450±7). This is ascribed to equilibration of the magma prior to the crystallization of these rocks with about 10% by weight of meteoric ground water. The concommittant increase of to about 1 Kb (the lithostatic load pressure) would depress the liquidus surfaces in the system Ne-Ks-Qz by about 200 ° C, allowing the magma to evolve continuously down temperature from oversatuated to undersaturated compositions. The chemical mechanism responsible for this trend has not been uniquely identified, but probably involved reduction of SiO₂ content in an open system. The outer, quartz-normative, rocks of the intrusion have ¹⁸O values ranging up to +5.5 and initial ⁸⁷Sr/⁸⁶Sr ratios ranging up to 0.7095. This is due to interaction of the solid rocks, down to temperatures approaching 500 ° C, with ground water which had been enriched in ¹⁸O and ⁸⁷Sr by previous exchange with the Precambrian country rocks. Minimum water/rock ratios are lower than in certain other known cases of interaction in the North Atlantic Tertiary Igneous Province.     

Performance‐based design using structural optimization

A new methodology for seismic design is proposed based on structural optimization with performance‐based constraints. Performance‐based criteria are introduced for the seismic design of new buildings. These criteria are derived from the National Guidelines for Seismic Rehabilitation of Buildings (Reference [19], Federal Emergency Management Agency (FEMA), ‘NHERP Guidelines for seismic rehabilitation of buildings’, Report Nos 273 and 274, Washington, DC, 1997) for retrofitting existing structures. The proposed design methodology takes into account the non‐linear behaviour of the structure. The goal is to incorporate in the design the actual performance levels of the structure, i.e. how much reserve capacity the structure has in an earthquake of a given magnitude. The optimal design of the structure minimizes the structural cost subjected to performance constraints on plastic rotations of beams and columns, as well as behavioural constraints for reinforced concrete frames. Uncertainties in the structural period and in the earthquake excitation are taken into account using convex models. The optimization routine incorporates a non‐linear analysis program and the procedure is automated. The proposed methodology leads to a structural design for which the levels of reliability (performance levels) are assumed to be quantifiable. Furthermore, the entire behaviour of the structure well into the non‐linear range is investigated in the design process. Copyright © 2000 John Wiley & Sons, Ltd.     

A New Protocol for the Astrometric Follow-up of Near Earth Asteroids

A new protocol was devised to improve the efficiency of astrometric follow-up observations of Near Earth Asteroids for the accurate determination of their orbits. It was implemented in the activities of the Spaceguard Central Node (SCN, a facility of the Spaceguard Foundation, established with the support of the European Space Agency) in the form of a Priority List. Here we describe this protocol and results obtained during five years of activity (2000–2004).     

Salinivibrio sp.YH4胞外丝氨酸蛋白酶EYHS耐盐性及生物信息学分析

摘要：目的 探讨菌株Salinivibrio sp.YH4分泌的丝氨酸蛋白酶EYHS的耐盐性及结构特征。方法 明胶底物酶谱法分析EYHS的耐盐性。应用生物信息学手段对EYHS及6种耐盐的S8家族丝氨酸蛋白酶结构特征进行分析。结果 EYHS在4 mol/L的NaCl溶液中仍具有活性,属于耐盐蛋白酶。EYHS及6种S8家族丝氨酸蛋白酶分子表面的loop区等无规则卷曲所占比例较高,α-螺旋与β-片层则主要位于酶分子内部。EYHS分子表面酸性氨基酸含量较高,且具有弱疏水内核。多序列比对发现蛋白酶的催化三联体两侧存在高度保守的基序和保守的极性氨基酸及芳香族氨基酸,并存在多个保守的Gly与Ala。同源模建和表面电荷分布显示,α螺旋和β片层围成了蛋白酶的催化腔,EYHS活性中心包含由Asp32、His65与Ser215组成的催化三联体,且催化位点区域表面静电势为负。结论 上述结构特征可能有助于耐盐丝氨酸蛋白酶EYHS在高盐环境下维持其稳定性和适度柔性,并有助于其催化功能的发挥,为深入研究耐盐丝氨酸蛋白酶的高盐环境适应性提供了一定的理论依据。     

Faunas from the upper silurian (upper ludlovian) in the ludlow-much wenlock district,England

Faunal lists for 17 sections in the Overton Formation are presented. Faunal diversity appears to increase towards the formations base while faunal dominance appears to increase towards its top.