Estimating proximate populations for an extensive set of locations in Australia

"The paper reports the use of Australian Resources Information System to calculate two proximate populations (people living within (i) 150 and (ii) 500 km) for the centroids of each of 3,000 half by half degree geodetic grid cells covering Australia. The use of proximate population data is exemplified by computing a map of the eighteen regions collectively containing a maximum fraction of the Australian population." The data used are from the 1981 census.     

Anoxia over the western continental shelf of India: bacterial indications of intrinsic nitrification feeding denitrification

Studies on the Arabian Sea coastal anoxia have been of immense interest, but despite its ecological significance there is sparse understanding of the microbes involved. Hence, observations were carried out off Goa (15 degrees 30'N, 72 degrees 40'E to 15 degrees 30'N, 72 degrees 59'E) to understand the processes that mediate the changes in various inorganic nitrogen species in the water column during anoxia. Water column chemistry showed a clear distinct oxic environment in the month of April and anoxic condition in October. Our study based on microbial signatures indicated that oxygen deficit appeared as a well-defined nucleus almost 40 km away from the coast during the oxic period (April) and spreads there after to the entire water column synchronizing with the water chemistry. Striking results of net changes in inorganic nitrogen species in nitrification blocked and unblocked experimental systems show that denitrification is the predominant process in the water column consuming available nitrate ( approximately 0.5 microM) to near zero levels within approximately 72 h of incubation. These observations have been supported by concomitant increase in nitrite concentration ( approximately 4 microM). Similar studies on denitrification-blocked incubations, demonstrate the potential of nitrification to feed denitrification. Nitrification could contribute almost 4.5 microM to the total nitrate pool. It was found that the relation between ammonium and total dissolved inorganic nitrogen (DIN) pool (r=0.98, p<0.001, n=122) was significant compared to the latter with nitrite and nitrate. The occurrence of high ammonium under low phosphate conditions corroborates our observations that ammonium does not appear to be locked under low oxygen regimes. It is suggested that ammonium actively produced by detrital breakdown (ammonification) is efficiently consumed through nitrification process. The three processes in concert viz. ammonification, nitrification and denitrification appear to operate in more temporal and spatial proximity than hitherto appreciated in these systems and this gives additional cues on the absence of measurable nitrate at surface waters, which was earlier attributed only to efficient algal uptake. Hence we hypothesize that the alarming nitrous oxide input into the atmosphere could be due to high productivity driven tighter nitrification-denitrification coupling, rather than denitrification driven by extraneous nitrate.     

岩石学标准化——国际地科联岩石系统分类学委员会

国际地科联(IUGS)岩石系统分类学委员会(CSP)负责协调统一国际上关于岩石分类命名的工作。将不同国家用不同语言对同种岩石有明显差别的命名统一起来是必要的。IUGS在国际标准方面所取得的最出色成果之一即是由CSP提出的现已广泛接受的侵入岩和火山岩矿物成分分类。     

再论元古界铁氧化物（Cu—U—Au—REE）矿床之热液成因

元古界铁氧化物Ｃｕ－Ｕ－Ａｕ－ＲＥＥ矿床的构造背景和矿物成分的多变性以及独特的形成深度，导致对其成因模式有不同的认识。本文研究表明，属该矿床类型的南澳大利亚ＥｍｍｉｅＢｌｕｆｆ铁氧化物矿床明显为热液成因，宏观、微观上均表面出叠加关系。其形成主要分两阶段，第一阶段形成富磁铁矿矿石，与源于中元古化长英质主要侵入事件的高温流体有关，随后的富赤铁矿矿化则与低温流体有关。全岩稳定同位素分析结果支持这一观点。     

TCM—93期间镶嵌在台风Robyn中的中尺度对流系统的结构

文章通过热带气旋运动（ＴＣＭ－９３）小型外场试验期间两次飞行研究了镶嵌在台风Ｒｏｂｙｎ环流中的一个中尺度对流系统（ＭＣＳ）。此ＭＣＳ最初形成在台风中心北面，但通过位于Ｒｏｂｙｎ与北侧的副热带高压脊之间的强盛中层偏东风很快向西平流移动。与ＭＣＳ出现的同时，台风由向西西北移动转为向北缓慢移动。本文研究ＭＣＳ的结构以便分析台风Ｒｏｂｙｎ移动的改变是否与ＭＣＳ的对流层中层涡旋环流有关。     

Evolutionary Timescale of the Pulsating White Dwarf G117-B15A: The Most Stable Optical Clock Known

We observe G117-B15A, the most precise optical clock known, to measure the rate of change of the main pulsation period of this blue-edge DAV white dwarf. Even though the obtained value is only within 1 sigma, P&d2;=&parl0;2.3+/-1.4&parr0;x10-15 s s-1, it is already constraining the evolutionary timescale of this cooling white dwarf star.     

The Properties of Supernova 1997cy Associated with GRB 970514

The extraordinary SN 1997cy associated with GRB 970514 has been observed photometrically and spectroscopically for nearly 2 yr. At the time of discovery, SN 1997cy was the brightest supernova (SN) ever observed (MV相似文献