Near Infrared Spectra of two Asteroids with low Tisserand Invariant

We present near infrared reflectance spectra from 0.8 to 2.5 μm of two asteroids with low Tisserand invariant, 1373 Cincinnati and 2906 Caltech. We compare our spectra with cometary nuclei and other asteroids in their class. Asteroids Cincinnati and Caltech have Tisserand invariant values of 2.72 and 2.97, respectively, values less than 3 are considered suggestive of cometary origin. The observed spectral slopes in the near-infrared are consistent with both the spectra of cometary nuclei and of primitive asteroids. However, both asteroids have features in the near-infrared that are not seen in cometary nuclei, but are present in other X-type asteroids. 1373 Cincinnati has a sharp slope change between 0.75 and 1.0 μm and 2906 Caltech has a broad and shallow absorption between 1.35 and 2.2 μm. Our attempts to model the visible and near-infrared spectrum of these two objects, with the components successfully used by Emery and Brown (2004, Icarus 164, 104–121) to fit Trojan asteroids, did not yield acceptable fits.Visiting Astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract to the National Aeronautics and Space Administration.     

气象服务产业化、商品化趋势及其对策

20世纪50年代以来,大气科学的发展和新科技在气象实践中的运用,不同程度地提高着气象成果的多样性、专业性、应用性和有效性,从而创造了气象成果产业化、商品化的物质技术条件;社会生产和居民生活对气象成果更为多样的、专一的需要,形成了气象成果产业化、商品化的市场条件。我国气象服务有偿化的发展已成为趋势;但从社会需求与气象服务自身现状考察,认真转变观念、积极调整结构、大力拓展市场、深化基础研究乃是加速气象成果产业化、商品化趋势的基本对策。     

Material exchange as heat engine for the corona-chromosphere transition region

We think that a steady material exchange in the upper solar atmosphere can act as a heat engine that cools the corona and heats the corona-chromosphere transition region. We have considered heat conduction from the corona and radiation loss in the transition region and have calculated the temperature, density and velocity distributions in the transition region. Also discussed is the relation between the material flux, the velocity boundary value and the thickness of the transition region.     

星际分子正—NH3和He的超精细跃迁碰撞截面和速率系数的理论计算

本文采用Ｒ矩阵传播方法，通过求解ＣＳ近似下的耦合方程，计算了星际分子云条件下正－ＮＨ３分子和Ｈｅ碰撞的超精细跃迁碰撞截面和速率系数，为研究天体的信息提供需用的基础数据。     

Geological, mineralogical and geochemical characteristics of the Radzimowice Au–As–Cu deposit from the Kaczawa Mountains (Western Sudetes, Poland): an example of the transition of porphyry and epithermal style

The sheeted quartz–sulfide veins of the Radzimowice Au–As–Cu deposit in the Kaczawa Mountains are related to Upper Carboniferous post-collisional potassic magmatism of the composite Zelezniak porphyry intrusion. Multiple intrusive activity ranges from early calc-alkaline to sub-alkaline and alkaline rocks and is followed by multiple hydrothermal events. Early crustally derived dacitic magma has low mg# (<63) and very low concentrations of mantle-compatible trace elements, high large-ion lithophile elements (LILE), moderate light rare-earth elements (LREE), and low high-field-strength elements (HFSE). Later phases of more alkaline rocks have higher mg# (60–70), and LILE, LREE, and HFSE characteristics that indicate mafic magma contributions in a felsic magma chamber. The last episode of the magmatic evolution is represented by lamprophyre dikes which pre-date ore mineralization and are spatially related to quartz–sulfide–carbonate veins. The dikes consist of kersantite and spessartite of calc-alkaline affinity with K₂O/Na₂O ratios of 1.1–1.9, mg# of 77–79, and high abundances of mantle-compatible trace elements such as Cr, Ni, and V. They have high LILE, low LREE, and low HFSE contents suggesting a subduction-related post-collisional arc-setting. The mineralization started with arsenopyrite that was strongly brecciated and overprinted by multiple quartz–carbonate phases associated with base-metal sulfides and Au–Ag–Bi–Te–Pb±S minerals. The sulfur isotope composition of sulfides ranges from –1.1 to 2.8 ³⁴S and suggests a magmatic source. At least two generations of gold deposition are recognized: (1) early refractory, and (2) subsequent non-refractory gold mineralization of epithermal style. Co-rich arsenopyrite with refractory gold and pyrite are the most abundant minerals of the early stage of sulfide precipitation. Early arsenopyrite formed at 535–345°C along the arsenopyrite–pyrrhotite–loellingite buffer and late arsenopyrite crystallized below 370°C along the arsenopyrite–pyrite buffer. Non-refractory gold associated with base-metal sulfides and with Bi–Te–Ag–Pb–S mineral assemblages has an average fineness of about 685, and is represented by electrum of two generations, and minor maldonite (Au₂Bi). Fluid inclusions from various quartz generations co-genetic with base-metal sulfides and associated with carbonates, tellurides and non-refractory gold indicate fluids with moderate salinity (9–15 wt% NaCl equiv.) and a temperature and pressure drop from 350 to 190°C and 1.2 to 0.8 kbar, respectively. According to the result of the sulfur isotope fractionation geothermometer the temperature of base-metal crystallization was in the range from 322 to 289°C. Preliminary results of oxygen isotope studies of quartz from veins indicate a gradual increase in the proportion of meteoric water in the epithermal stage. The gold to silver ratio in ore samples with >3 ppm Au is about 1:5 (geometric mean). Hydrothermal alteration started with sericitization, pyritization, and kaolinitization in vein selvages followed by alkaline hydrothermal alteration of propylitic character (illitization and chloritization), albitization and carbonatization. The mineralization of the Radzimowice deposit is considered as related to alkaline magmatism and is characterized by the superposition of low-sulfidation epithermal mineralization on higher-temperature and deeper-seated mesothermal/porphyry style.Editorial handling: B. Lehmann     

Ab initio study of the high-pressure behavior of CaSiO3 perovskite

Using density functional simulations, within the generalized gradient approximation and projector-augmented wave method, we study structures and energetics of CaSiO₃ perovskite in the pressure range of the Earths lower mantle (0–150 GPa). At zero Kelvin temperature the cubic CaSiO₃ perovskite structure is unstable in the whole pressure range, at low pressures the orthorhombic (Pnam) structure is preferred. At 14.2 GPa there is a phase transition to the tetragonal (I4/mcm) phase. The CaIrO₃-type structure is not stable for CaSiO₃. Our results also rule out the possibility of decomposition into oxides.

Ethnic Enclave Reconfiguration: A ‘new’ Chinatown in the Making

Years of past research on traditional Chinatowns were based on the assumption that Chinatown is an ethnic enclave for a single ethnic minority, i.e. the Chinese. In recent years, one could observe significant changes over Chinatowns in terms of more Vietnamese presence. Yet, the transition process as an object of study is much under-represented in the literature on ethnic enclaves. Looking at ethnic business transition from Hong Kong to Vietnamese in Toronto’s Chinatown West, this paper argues strongly that ‘multiple ethnicity’ can coexist in an enclave. For this case study, the Chinatown is being reconfigured into a ‘new’ Chinatown. Drawing upon data from the authors’ Vietnamese Business Database that covers information between 1983 and 2003, we present both spatial and temporal analyses that offer insights into how the Vietnamese businesses grow through time. Our findings support the existence of a Vietnamization process in Toronto Chinatown West. However, its evolution is still in an infant stage. In some aspects, the incoming Vietnamese businesses display similarities with the remaining Hong Kong businesses. In sum, a total reconfiguration of Chinatown West in form and business nature is still unaccomplished. The conventional enclave concept which bases on the singularity of ethnic group has to be abandoned in view of rising occurrence of ethnic transition, particularly in this globalizing era.     

Ore-forming fluid and mineralization of Caijiaying and Dajing polymetallic ore deposits

Fluid inclusions from the Dajing and Caijiaying deposits have nearly the same ho-mogenization temperature. Correlation between temperature and salinity shows that both Sn-and Cu-bearing fluids Sn and Cu were present in the Dajing deposit but only one kind of fluids continuously evolved in the Caijiaying deposit. Study on rare earth elements (REE) in ancient fluid from the inclusions indicates that the fluid of Sn mineralizing stage in Dajing was derived from remelting magma of the continental crust, and the fluid of Cu-Pb-Zn mineralizing stage in the Dajing deposit and the fluid of Cu-Pb-Zn mineralization in the Caijiaying deposit were derived from the mantle. It is concluded that the Cu-Pb-Zn mineralizations in the Dajing and Caijiaying deposits resulted from the identical tectono-thermal event of magma-fluids induced by Mesozoic tectonic transition and extension in the eastern part of North China Craton.     

制度演进与城市旧城区更新活动的实证研究——以武汉市汉正街为例

改革开放以来我国城市旧城区进行了若干次大规模的旧城更新活动,以武汉市汉正街为实证对象,将其更新活动分为3个阶段展开研究,总结分析各阶段国家权力结构调整、土地有偿制度深化和住房制度改革等社会制度环境的变化特征,探讨了社会制度发展在解决旧城问题上所发挥的作用及存在问题。结果表明:制度环境的变迁使旧城更新成为制度容易缺失的领域;制度目标的更迭使旧城更新渐成为公共领域与私人领域的利益争夺舞台;旧城更新的发展过程本质上是公权力与私权利交织的结果。