Precursor times of abnormal <Emphasis Type="Italic">b</Emphasis>-values prior to mainshocks

Seismic observations exhibit the presence of abnormal b-values prior to numerous earthquakes. The time interval from the appearance of abnormal b-values to the occurrence of mainshock is called the precursor time. There are two kinds of precursor times in use: the first one denoted by T is the time interval from the moment when the b-value starts to increase from the normal one to the abnormal one to the occurrence time of the forthcoming mainshock, and the second one denoted by T _p is the time interval from the moment when the abnormal b-value reaches the peak one to the occurrence time of the forthcoming mainshock. Let T* be the waiting time from the moment when the abnormal b-value returned to the normal one to the occurrence time of the forthcoming mainshock. The precursor time, T (usually in days), has been found to be related to the magnitude, M, of the mainshock expected in a linear form as log(T)?=?q?+?rM where q and r are the coefficient and slope, respectively. In this study, the values of T, T _p , and T* of 45 earthquakes with 3?≤?M?≤?9 occurred in various tectonic regions are compiled from or measured from the temporal variations in b-values given in numerous source materials. The relationships of T and T _p , respectively, versus M are inferred from compiled data. The difference between the values of T and T _p decreases with increasing M. In addition, the plots of T*/T versus M, T* versus T, and T* versus T-T* will be made and related equations between two quantities will be inferred from given data.     

Radioactive anomalies associated with the graphite-bearing metasediments,Wadi Umm Gheig area,Central Eastern Desert,Egypt

The study area is located in the central part of the Eastern Desert of Egypt and is mainly covered by different varieties of Precambrian basement rocks represented mainly by younger and older granites, metadiorite, metavolcanics, and metasediments. The analysis and interpretation of airborne gamma-ray spectrometric survey data are essentially based on the computation of the three radioelements (U, Th, and K) favorability indices, estimation of uranium migration rate percentage, variation of eU with eTh and eU/eTh ratio, and the construction of the contour map of the (eU-eTh/3.5) in the different rock units. The highest percent of uranium migration- out or leaching rate is connected with the red and pink granites of Gebel Kadabora El-hamra, metadiorite, and red and pink granites of G. Umm Rakham (??20.8%, ??18.57%, and ??8.45% respectively), which indicates that they could represent a major U-source bodies in the area. It was observed that the metasediments and associated graphite-bearing schists west and northwest of G. Kadabora El-hamra reflect more precipitation than the other locations around the pluton (the uranium migration rates varies between 2.59 and 30%) which mean that the graphite may have acted as a reducing agent for uranium carried in oxidizing fluids (surface meteoric water) and resulted in its precipitation. In the light of the availability of uranium source, its mobility, and graphite-bearing metasediments, the area has a good potential for the possible occurrence of uranium mineralization.     

Monitoring agricultural cropping patterns across the Laurentian Great Lakes Basin using MODIS-NDVI data

The Moderate Resolution Imaging Spectrometer (MODIS) Normalized Difference Vegetation Index (NDVI) 16-day composite data product (MOD12Q) was used to develop annual cropland and crop-specific map products (corn, soybeans, and wheat) for the Laurentian Great Lakes Basin (GLB). The crop area distributions and changes in crop rotations were characterized by comparing annual crop map products for 2005, 2006, and 2007. The total acreages for corn and soybeans were relatively balanced for calendar years 2005 (31,462 km² and 31,283 km², respectively) and 2006 (30,766 km² and 30,972 km², respectively). Conversely, corn acreage increased approximately 21% from 2006 to 2007, while soybean and wheat acreage decreased approximately 9% and 21%, respectively. Two-year crop rotational change analyses were conducted for the 2005–2006 and 2006–2007 time periods. The large increase in corn acreages for 2007 introduced crop rotation changes across the GLB. Compared to 2005–2006, crop rotation patterns for 2006–2007 resulted in increased corn–corn, soybean–corn, and wheat–corn rotations. The increased corn acreages could have potential negative impacts on nutrient loadings, pesticide exposures, and sediment-mediated habitat degradation. Increased in US corn acreages in 2007 were related to new biofuel mandates, while Canadian increases were attributed to higher world-wide corn prices. Additional study is needed to determine the potential impacts of increases in corn-based ethanol agricultural production on watershed ecosystems and receiving waters.     

Diatoms grow faster using ammonium in rapidly flushed eutrophic Dokai Bay,Japan

The importance of the nitrogen source for phytoplankton growth in a highly eutrophic embayment, Dokai Bay, was investigated. The DIN concentration often exceeded 100 μM of which 40–70% was NH₄ ⁺. During two incubation experiments, the natural assemblage of mainly diatoms took up NH₄ ⁺ instead of NO₃ ⁻. The growth of two Skeletonema species isolated in Dokai Bay were significantly faster on NH₄ ⁺ (1.86 and 1.27 div. d⁻¹ respectively) than on NO₃ ⁻ (1.55 and 1.04 div. d⁻¹ respectively). Our results indicated that these diatoms could grow faster by using NH₄ ⁺ compared to NO₃ ⁻ in this eutrophic bay.     

Adjoint Sensitivity Analyses on the Anomalous Circulation Features in East Asian Summer Monsoon

ＡｄｊｏｉｎｔＳｅｎｓｉｔｉｖｉｔｙＡｎａｌｙｓｅｓｏｎｔｈｅＡｎｏｍａｌｏｕｓＣｉｒｃｕｌａｔｉｏｎＦｅａｔｕｒｅｓｉｎＥａｓｔＡｓｉａｎＳｕｍｍｅｒＭｏｎｓｏｏｎ①ＹａｎｇＹａｎ（杨燕），ＬｉＺｈｉｊｉｎ（李志锦）ａｎｄＪｉＬｉｒｅｎ（纪立人）Ｉ...     

航空重力数据向下延拓的倒锥法(上)——方法的提出和存在性

基于离散 Possion积分提出了一种灵活直接的向下延拓新方法 ,证明了方法的存在性 ,利用模拟数据进行的数值实验取得了很好的效果。     

The relative importance of physicochemical factors and crustacean zooplankton as determinants of rotifer density and species distribution in lakes adjacent to the Yangtze River, China

The planktonic community of freshwater Rotifera in 27 subtropical lakes was studied to assess the relative importance of physicochemical factors and crustacean zooplankton as determinants of rotifer density and species distribution. Factor analysis and multiple linear regressions showed that 21.9% and 29.9% of the variance in rotifer density was explained by physicochemical factors and crustaceans, respectively. Larger rotifer density was possible in shallower lakes with higher concentration of inorganic nitrogen and less herbivorous crustaceans such as Sinocalanus dorrii and Daphnia. Redundancy analysis showed that the variances of rotifer species distribution explained by crustaceans and physicochemical factors were 26.9% and 31.0%, respectively. Further analysis demonstrated that the variances explained by pure crustaceans and pure physicochemical factors were 12.5% and 16.6%, respectively. However, these two percentages were not statistically different. Rotifer species distribution was strongly associated with Chl a and Moina micrura. Their coexistence with crustaceans seemed to be determined by their defense against potential predators and competitors.     

Peierls dislocation modelling in perovskite (CaTiO<Subscript>3</Subscript>): comparison with tausonite (SrTiO<Subscript>3</Subscript>) and MgSiO<Subscript>3</Subscript> perovskite

We present here a numerical modelling study of dislocations in perovskite CaTiO₃. The dislocation core structures and properties are calculated through the Peierls–Nabarro model using the generalized stacking fault (GSF) results as a starting model. The GSF are determined from first-principles calculations using the VASP code. The dislocation properties such as collinear, planar core spreading and Peierls stresses are determined for the following slip systems: [100](010), [100](001), [010](100), [010](001), [001](100), [001](010), and All dislocations exhibit lattice friction, but glide appears to be easier for [100](010) and [010](100). [001](010) and [001](100) exhibit collinear dissociation. Comparing Peierls stresses among tausonite (SrTiO₃), perovskite (CaTiO₃) and MgSiO₃ perovskite demonstrates the strong influence of orthorhombic distortions on lattice friction. However, and despite some quantitative differences, CaTiO₃ appears to be a satisfactory analogue material for MgSiO₃ perovskite as far as dislocation glide is concerned.     

Detection of the Long Period Long Duration (LPLD) Events in Time-and Frequency-Domain

Long Period Long Duration (LPLD) signals are unusual seismic events that can be observed during hydraulic fracturing. These events are very similar in appearance to tectonic tremors sequences, which were first observed in subduction zones. Their nature is not well known. LPLD might be related to the productivity of the reservoir. Different methods of the LPLD events’ detection recorded during hydraulic fracturing are presented. The author applied two methods for LPLD detection–Butterworth filtering and Continuous Wavelet Transform (CWT). Additionally, a new approach to LPLD events detection–instantaneous seismic attributes–was used, common in a classical seismic interpretation but not in microseismic monitoring.     

A reinterpretation of two chertbreccias from the Proterozoic basins of India

Several horizons of a unique lithotype called “chertbreccia” are interbedded within the Proterozoic platform sediments of the Peninsular India. These cherty rocks with brecciated texture appearing as blocky masses were earlier diversely interpreted as being products of disparate processes such as fault-zone breccias, collapse breccias, and so on. Two of these horizons, one from the Kaladgi Basin (Dharwar Craton) and the other from the Dhar Forest Inlier of the Vindhyanchal Basin (Bundelkhand — Aravalli Craton) are compared in context of their geological setting, field relations and petrological constitution. A model of the mode of development of these peculiar rocks is reconstructed, taking into account their characters and limitations of previous interpretations. They are interpreted as transported debris deposits of syntectonogenic material released during the episodic activity of the growth faults of the Kaladgi and Vindhyanchal Basins that was diagenetically silicified.