Automated mapping of the ocean floor using the theory of intrinsic random functions of order k

High-quality contour maps can be computer drawn from single track echo-sounding data by combining Universal Kriging and the theory of intrinsic random function of order K (IRFK). These methods interpolate values among the closely spaced points that lie along relatively widely spaced lines. The technique provides a variance which can be contoured as a quantitative measure of map precision. The technique can be used to evaluate alternative survey trackline configurations and data collection intervals, and can be applied to other types of oceanographic data.     

On the relationship between cumulus mineralogy and trace and alkali element chemistry in an Archean granite from the Barberton region,South Africa

A change in the liquidus mineralogy from plagioclase-quartz-biotite to plagioclase-quartz-K feldspar-biotite during the in situ fractional crystallization of a granitic magma has a marked effect on the abundance of and interrelationships between Ba, Rb, Sr, K₂O and Na₂O. During plagioclase fractionation, Ba and Rb enrich in successive solids and melt, while Sr is depleted. The K₂O content of the solid phase (around 1%) is very different from that of the melt (greater than about 3%) while Na₂O contents are similar (about 4–5%) so that variations in the amount of intercumulus melt result in wide variation in the Na₂O/K₂O ratio (from about 5 in cumulus-rich to about 1 in intercumulus-rich samples). The incoming of K feldspar as a cumulus phase causes Ba to be depleted along with Sr in successively formed solids, while Rb continues to be enriched. A pronounced compositional hiatus with respect to trace elements therefore results. The K₂O and Na₂O contents of melt and cumulate are now similar (around 5% K₂O and 4% Na₂O), so that little scatter in Na₂O/K₂O ratio (around 1) occurs as a result of variation in the amount of intercumulus melt. In general, trace element data from a natural example in the Barberton Mountain Land, South Africa, fit the models well, although the observed scatter of the data is somewhat greater than predicted by simple variation in cumulus-intercumulus proportions—possibly the result of the non-uniform distribution of biotite in the samples.     

Investigation of a cyclic laterally loaded model pile group

In certain regions of the world, designing deep foundations to withstand seismic loading is a reality. Seismic loading of structures and foundations reaches its most critical state as a cyclic lateral force. The response of soils and foundations to repetitive lateral forces is highly complex, relegating most design methods to be based upon overly conservative rules-of-thumb. The primary objective of this research was to analyze the mechanics of seismic loading on pile groups in clay soils. To achieve this a model testing facility was constructed to house a fully instrumented 1×5 model pile group that was subjected to cyclic lateral loading. An empirically based method for pile group design is suggested based upon the results generated from model pile group testing.     

多层螺旋CT在诊断中心型肺栓塞的初步应用

目的是评价多层螺旋CT诊断中心型肺动脉栓塞的诊断价值。方法：6例肺栓塞病人行多层螺旋CT血管造影检查，结合三维成像技术进行图像分析。结果：6例病人的肺动脉病变以及主肺动脉扩张、肺梗死表现均较好显示，肺动脉病变主要表现为完全性或部分性充盈缺损。结论：多层螺旋CT是一种有效的无创性诊断中心型肺动脉栓塞的检查方法。     

Influence of local environmental conditions and bleaching histories on the diversity and distribution of Symbiodinium in reef-building corals in Tanzania

Pollution, turbidity and coral bleaching history, as well as coral diversity, vary along the Tanzanian coastline. Prior to this study, it was not known whether exposure to such environmental variation might have influenced the diversity and distribution of Symbiodinium along this coastline. Such information can provide insight into whether Tanzanian reef-building corals develop adaptation to current trends of climate change. Here, 10 reef-building coral samples were collected from different reefs along the Tanzanian coast with different micro-environments and bleaching histories. The ITS-2 region of ribosomal DNA was employed in the characterisation of Symbiodinium harboured by reef-building corals. DGGE fingerprints and DNA sequences showed that most coral species host a single Symbiodinium type, which is maintained throughout the coast regardless of local environmental differences. We present polymorphic symbioses in Acropora spp., Millepora sp. and Galaxea fascicularis in mainly turbid and warm environments as a sign of adaptation to harsh conditions. However, such adaptation may not provide marked resistance to bleaching because Acropora is a bleaching-susceptible genus.     

Large aerosol particles in cirrus type clouds

Research flights in November 1990 over the central parts of the United States, Wyoming and Colorado, were aimed to the investigation of the properties and microstructure of cirrus clouds (mainly cirrocumulus lenticularis). Among the other parameters measured on board the NCAR Saberliner were the concentration and size distribution of submicron particles and, in some cases, the particle deliquescence. For coarse insoluble particles found inside and outside of cloud elements, size distributions and morphology information were obtained by evaluating inertial impactor samples with an optical microscope and scanning electron microscope. In addition, the coarse particle composition was determined by x-ray energy spectrum analysis. The following conclusions from these measurements are:The large and coarse particle size distribution can be roughly simulated by a log-normal function with the modus around r=0.5 μm. Particle concentrations are very variable between several tenths and several particles per cm³. Particle volume distribution features a distinct maximum around 0.75 μm without a broad plateau which was observed in the case of sampling at lower altitude. Aerosol composition heterogeneity at cirrus cloud level is well documented by the evaluation of the fine particle sampling taken with the UMR sampling system. This heterogeneity can be partly explained by the interaction between aerosol and cloud elements, which is documented by the measured particle size distribution curves inside and outside of cloud elements. Assuming that particle deliquescence is caused by H₂SO₄ and/or by (NH₄)₂SO₄, particle soluble mass fractions were found to be around 30% in the first case and about 40% in the second. The most frequently occurring elements in large and coarse particles at cirrus cloud level were Si, Cl, Ba, S, Ca and C.