Temperature measurements of electrostatic shocks in?laser-produced counter-streaming plasmas

Collisionless shocks in counter-streaming plasmas, created by the high-power laser system Gekko XII HIPER, are investigated. The shock structure and density are measured by optical diagnostics such as shadowgraphy, interferometry, and streaked interferometry. The plasma density and temperature are estimated from self-emission measurements with visible light by streaked optical pyrometer and gated optical imager. Brightness temperatures are calculated considering the efficiency of the detectors, and electron temperatures are estimated.     

Application of the QUILF thermobarometer to the peralkaline trachytes and pantellerites of the Eburru volcanic complex, East African Rift, Kenya

The Quaternary Eburru volcanic complex in the south-central Kenya Rift consists of pantelleritic trachytes and pantellerites. The phenocryst assemblage in the trachytes is sanidine + fayalite + ferrohedenbergite + aenigmatite ± quartz ± ilmenite ± magnetite ± pyrrhotite ± pyrite. In the pantellerites, the assemblage is sanidine + quartz + ferrohedenbergite + fayalite + aenigmatite + ferrorichterite + pyrrhotite ± apatite, although fayalite, ferrohedenbergite and ilmenite are absent from more evolved rocks (e.g. with SiO₂ > 71%). QUILF temperature calculations for the trachytes range from 709 to 793 °C and for the pantellerites 668–708 °C, the latter temperatures being among the lowest recorded for peralkaline silicic magmas. The QUILF thermobarometer demonstrates that the Eburru magmas crystallized at relatively low oxidation states (ΔFMQ + 0.5 to − 1.6) for both trachytes and pantellerites. The trachytes and pantellerites evolved along separate liquid lines of descent, the trachytes possibly deriving from a more mafic parent by fractional crystallization and the pantellerites from extreme fractionation of comenditic magmas.     

绿潮迁移过程中环境要素与浒苔藻体生物学特征的相关性分析

浒苔(Ulva prolifera)引起的大规模绿潮起源于黄海南部,在向北迁移过程中生物量迅速扩增,在海州湾附近(35°N左右)迅速增加达到峰值.在绿潮漂浮迁移过程中,海水表层温度、溶解无机氮(dissolved inorganic nitrogen,DIN)和磷酸盐(PO43--P)变化显著.本文以迁移过程中的浒苔为...     

Cell-zonal textures of tinguaites from the Kola Peninsula

Textures of tinguaite dykes cutting the alkaline Khibiny massif in the Kola Peninsula, Russia, are described. They are characterized by a combination of a fractal microfracture network dividing rock into pencil-like cells and of a concentric rhythmical zonation in almost all of them. The latter is formed by interchange of volatile-enriched and volatile-depleted mineral zones. The location of the textures only where dykes contact host khibinites appears to point out the contraction nature of the microfracture network. The cooling time calculated agrees well with this hypothesis. The zonation appears to have arisen through autometamorphic processes with two main competing factors, namely (a) overall cooling of the system and (b) periodic depletion of it in some elements, mainly Na and K. Another mechanism which may be applied to explain the zonation is the known Marangoni Instability effect at the early stage of evolution of the volatile-saturated phonolite melt. Thus, tinguaite textures are caused by nonspecific influences external to the system and may be regarded as an example of self-organization in nature.     

High-Resolution Studies of the Solar Polar Magnetic Fields

We present high-resolution studies of the solar polar magnetic fields near sunspot maximum in 1989 and towards sunspot minimum in 1995. We show that, in 1989, the polar latitudes were covered by several unipolar regions of both polarities. In 1995, however, after the polar field reversal was complete, each pole exhibited only one dominant polarity region.Each unipolar region contains magnetic knots of both polarities but the number count of the knots of the dominant polarity exceeds that of the opposite polarity by a ratio of order 4:1, and it is rare to find opposite polarity pairs, i.e., magnetic bipoles.These knots have lifetimes greater than 7 hours but less than 24 hours. We interpret the longitudinal displacement of the knots over a 7-hour period as a measure of the local rotation rate. This rotation rate is found to be generally consistent with Snodgrass' (1983) magnetic rotation law.In an attempt to obtain some insight into the operation of the solar dynamo, sketches of postulated subsurface field configurations corresponding to the observed surface fields at these two epochs of the solar cycle are presented.     

Tracing the source of metals in Geogas from metal deposits in a loess-covered region北大核心CSCD

In order to test the distribution characteristics of metallogenic elements and the application effectiveness of the traee elements and REE for tracing the source of Geogas anomaly, the distribution characteristics of metallogenetic elements .trace elements and REE in different media of the Jiaolongzhang Pb-Zn deposit underneath the loess have been studied in this paper. Results indicate that the distribution characteristics of Geogas anomalous elements over the concealed orebodies are coincided with those of the enriched elements of ores, while the distribution characteristics of trace elements and REE in background Geogas samples are distinctly different from those of other media, indicating that the source of background Geogas materials is influenced by various factors( geological bodies, lab environment and blank reagent). The similar distribution characteristics of the trace elements in the Geogas samples of anomalous areas and in the ores suggested that Geogas anomaly is affected by concealed orebodies in depth. The difference between REE patterns of the Geogas samples of the anomalous area and those of other solid media might be caused by inadequate analytical precision and low collecting efficiency of the instrument. It is believed that the REE tracing method can provide the information on the source of Geogas anomaly if the analytical precision and collecting efficiency of REE could be constantly increased.     

Spatial coherency analysis of seismic ground motions from a rock site dense array implemented during the Kefalonia 2014 aftershock sequence

The objective of studies presented in this paper is to analyse the spatial incoherency of seismic ground motions using signals from a velocimeter dense array located on a rock site, recording the aftershock sequence of the two M6 Kefalonia earthquakes that occurred in January/February 2014 (Kefalonia island, Greece). The analyses are carried out with both horizontal and vertical components of velocigrams for small separation distances of stations (<100 m). The coherencies of seismic ground motions identified from strong motion windows are compared with those identified from coda parts of signals. It is realized that there is no significant difference between the coherencies estimated from those two parts of signals. The influence of earthquake event number on the result of coherencies and the dispersions of coherencies estimated from different earthquake events are presented. Finally, coherencies estimated from the dense array are compared with several coherency models proposed and widely used in the literature. The possibility of modifying some parameters of those existing coherency models to fit with in situ coherencies are discussed and presented. Copyright © 2017 John Wiley & Sons, Ltd.     

Exploration geochemistry—Distribution of elements and recognition of anomalies

The exploration geochemist faces a serious problem in reconciling theoretical statistics with the empirical distribution of elements in materials in the earth's crust. The results of computer-simulation experiments being conducted by the Exploration Geochemistry Group at the University of New Brunswick illustrate some of the problems of the relation between frequency distributions and spatial distributions of elements and raise some interesting questions about sampling patterns and physical size of samples. Most importantly, the simulation experiments and empirical examples support the contention that attempts to make an assumption of normality more efficient by performing log transformations on positively skewed data may defeat the purpose of statistical analysis for exploration work. New developments in computer-data presentation and interpretation, including population sorting and classification, illustrate the increasing use of the computer in exploration geochemistry.     

Reservoir sediments – a witness of mining and industrial development (Malter Reservoir, eastern Erzgebirge, Germany)

The Malter Reservoir is situated about 30 km south of Dresden (eastern Germany) in a historical mining area of the eastern Erzgebirge. It was built in 1913 for the protection from floodwaters, droughts and for generating electricity. The river Rote Wei?eritz is the main source of clastic input into the lake. Geochemical and sedimentological data of gravity-and piston-cores, recovered from the deepest point of the lake, document the environmental history of the drainage area since 1963. ¹³⁷Cs dating gives an average sedimentation rate of ∼2.9 cm/year. Within the whole core, heavy metals are strongly enriched (parentheses refer to enrichment factors as compared with average shale): cadmium (290), silver (140), bismuth (90), antimony (25), lead (21), zinc (14), tin (13), uranium (9), tungsten (9), molybdenum (5), copper (4), thallium (3) and chromium (2). Enrichments are detectable for the whole registered time-period of 81 years. Peaks of up to 27 mg/kg silver, 37 mg/kg bismuth, 91 mg/kg cadmium, 410 mg/kg chromium, 240 mg/kg copper, 20 mg/kg molybdenum, 14000 mg/kg phosphorus, 740 mg/kg lead, 6,5 mg/kg antimony, 74 mg/kg tin, 52 mg/kg tungsten and 1900 mg/kg zinc reflect local events caused by human impact. Inputs from different pollution sources at different times are represented by highly variable elemental concentrations and ratios within the core. High pH values within the water and the sediment column, the large adsorption capacity of the fine-grained C_org.-rich sediment, and the presence of low Eh-values and sulphide ions in the sediment prevent the remobilisation of the toxic elements. Erosion of these contaminated sediments during floods, channel flows or resuspension during removal of the sediments may lead to a downstream transfer of pollutants. Contents of P and C_org., as well as diatom abundance, indicate a change from oligotrophic to eutrophic conditions in the lake during ∼1940–1950. This was mainly caused by high agricultural activity in the drainage area. Reduced contents of Cu, Zn, Cd and Cr since the reunification of East and West Germany are obviously caused by increasing environmental protection measures, such as wastewater purification and especially the closing of contaminating industries. Revision received: 23 September 1999 · Accepted: 17 December 1999