TRACE and Yohkoh Observations of High-Temperature Plasma in a Two-Ribbon Limb Flare

The ability of the Transition Region and Coronal Explorer (TRACE) to image solar plasma over a wide range of temperatures (Te approximately 104-107 K) at high spatial resolution (0&farcs;5 pixels) makes it a unique instrument for observing solar flares. We present TRACE and Yohkoh observations of an M2.4 two-ribbon flare that began on 1999 July 25 at about 13:08 UT. We observe impulsive footpoint brightenings that are followed by the formation of high-temperature plasma (Te greater, similar10 MK) in the corona. After an interval of about 1300 s, cooler loops (Te<2 MK) form below the hot plasma. Thus, the evolution of the event supports the qualitative aspects of the standard reconnection model of solar flares. The TRACE and Yohkoh data show that the bulk of the flare emission is at or below 10 MK. The TRACE data are also consistent with the Yohkoh observations of hotter plasma (Te approximately 15-20 MK) existing at the top of the arcade. The cooling time inferred from these observations is consistent with a hybrid cooling time based on thermal conduction and radiative cooling.     

Inter-provincial migration in Spain: temporal trends and age-specific patterns

"This paper provides interpretation of the changing patterns of internal migration in Spain at the inter-provincial scale, and new analysis of age-specific migration during the 1980s using a 10% sample of anonymised records from the 1991 census. Schedules of age-specific gross migration rates are constructed and classified according to their shape and level relative to the national schedule, and the relationships between in-migration and out-migration rates are examined for four selected age groups to demonstrate how aggregate patterns of inter-provincial migration conceal a wide diversity of age specific experience."     

Metallurgy at the Crossroads: New Analyses of Copper-based Objects at Tianshanbeilu, Eastern Xinjiang, China

Tianshanbeilu is the largest Bronze Age site in eastern Xinjiang, China. Stretching across the entire second millennium BC, it performed a prominent role in connecting the Hexi corridor, Central China and the steppe. A further insight into the metallurgical tradition and the metal supply network is of vital importance to improve our understanding of its multi-connected nature. This paper offers a new set of chemical and isotopic data on the copper-based objects at Tianshanbeilu, including alloying elements, trace elements (impurities) and lead isotopes. Combining the concentrations of arsenic and antimony reveals that arsenic was introduced to copper partially due to the use of specific minerals tethrahedrite-tennantite. Lead isotopes demonstrate that multiple sources of copper were employed at Tianshanbeilu and a majority of them are characterized by common lead, which appears rather different from those of the Central Plains and the Hexi corridor, but highly consistent with local ores. Surprisingly, one object at Tianshanbeilu contains the well-known highly radiogenic lead. This object undoubtedly marks the westernmost boundary of the distribution of the highly radiogenic lead. We also anticipate that more lead isotopic analyses in NW China will further contribute to the study of the highly radiogenic lead in Central China.     

冲击回转钻探用БУК-75型新式钻机

目前在不稳固的松散岩层中打浅钻孔（50—80公尺）多半利用手动钻探设备。这首先说明还没有适宜的钻机来代替繁重的和高价的手动钻探。在1955年水利工程设计院（作者И.А.特鲁索夫和А.М.科帕契夫）曾设计了БУК-75型钻机,而后又小批地制造了,它的技术规格如下。     

勘探坑道掘进凿岩的机械化

人力劳动在地质勘探及工程地质工作中仍占有相当的地位,其中勘探坑道掘进用人力打眼的工作是繁重的。例如,在中硬岩石中钻进深1．5公尺及直径35公厘的一个孔,就需要3．14工时。掘进勘探坑道时由于缺乏动力来源,采用现有凿岩机械在一些情况下又不可能,所以工作量很大的繁重而成本高的人力凿岩工作急切需要使之机械化。     

苏联石油工业中地球物理勘探方法的发展情况

地球物理工作在石油工业中已获得了公认,并在普查和勘探油田的综合地质勘探工作中居于牢固而称职的地位.三十七年前,苏联就开始了第一次勘探地球物理工作,最初是用来研究库尔斯克磁力异常上的鉄矿床.1919年根据列宁的指示在库尔斯克地区开始了磁力测量.1925年在乌拉尔-恩巴油区开始了第一次用地球物理勘探石油的工作,旨在寻找盐丘构造.     

论次生白云岩

此稿为苏联专家A.C瓦良卓夫同志对东北某矿区地质人员所提有关含矿白云岩研究方法问题的答复。文中若干地方编者曾略加改动。——编者     

不连续植被二向性反射的几何光学与辐射传输一体化综合模型初探

本文论述作者对不连续植被冠层与辐射间相互作用机理研究的最新进展,提出了建立不连续植被二向性反射分布函数的几何光学与辐射传输一体化综合模型的设想和基本理论。该综合模型的建立以Li-Strahler间隙概率模型为基础,在大尺度上用纯几何光学模型反映植被的结构特征,在适于辐射传输模型的尺度上则以冠层内的间隙概率处理叶丛的截获辐射与散射。本文详细说明了冠层内任意高度的间隙率模型,也介绍了多次散射的建模方法。     

地质时期古气候研究中的天文周期的稳定性

在过去500Ma的地质时期内影响地球气候的基本天文频率的预期变化也许能在地质记录中识别出来,并且这种影响已在几种情况下推理得出.计算结果表明,由于过去5亿年内,地-月距离以及日长随地质年龄增大而缩短,导致基本周期如黄赤交角周期及气候差周期由54至35,41至29,23至19和19至16千年的缩短,而在这一时间内,岁差常数由50弧秒/年增至61弧秒/年.由于行星系统不规则运动所造成的基频的改变极小,它们对气候岁差周期、黄赤交角周期及地球绕日轨道的偏心率周期的影响可以忽略不计,医此,用于研究第四纪气候的偏心事周期对前第四纪而言也许可以认为是大致恒定的.