Differences between Paleozoic Asia and Paleozoic North America as shown by the distribution of ultrahigh-pressure (UHP) terranes   总被引：2，自引：2，他引：0  

John J.W. Rogers  Stefanie L.D. Bernosky 《Gondwana Research》2008,13(3):428-433

Numerous UHP suites developed in East Asia during the Paleozoic because subduction occurred in an area of low thermal gradients. By contrast, no Paleozoic UHP suites formed in North America or in terranes accreted to it because all subduction under accreting terranes occurred in an area of high thermal gradients centered in North America. High thermal gradients beneath North America are also demonstrated by an abundance of intracratonic rifts and basins. These differences in thermal gradients between North America and East Asia may have been caused by a very large mantle convection cell, with a rising limb under North America and a descending limb in an oceanic area where East Asia was assembled.  相似文献   

Multiscale Edge Detection in the Corona     

C. Alex Young  Peter T. Gallagher 《Solar physics》2008,248(2):457-469

Coronal Mass Ejections (CMEs) are challenging objects to detect using automated techniques, due to their high velocity and diffuse, irregular morphology. A necessary step to automating the detection process is to first remove the subjectivity introduced by the observer used in the current, standard, CME detection and tracking method. Here we describe and demonstrate a multiscale edge detection technique that addresses this step and could serve as one part of an automated CME detection system. This method provides a way to objectively define a CME front with associated error estimates. These fronts can then be used to extract CME morphology and kinematics. We apply this technique to a CME observed on 18 April 2000 by the Large Angle Solar COronagraph experiment (LASCO) C2/C3 and a CME observed on 21 April 2002 by LASCO C2/C3 and the Transition Region and Coronal Explorer (TRACE). For the two examples in this work, the heights determined by the standard manual method are larger than those determined with the multiscale method by ≈10% using LASCO data and ≈20% using TRACE data.  相似文献   

Abrupt transition from fractional crystallization to magma mixing at Gorely volcano (Kamchatka) after caldera collapse     

Maxim Gavrilenko  Alexey Ozerov  Philip R. Kyle  Michael J. Carr  Alex Nikulin  Christopher Vidito  Leonid Danyushevsky 《Bulletin of Volcanology》2016,78(7):47

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Daily streamflow forecasting by machine learning methods with weather and climate inputs     

Kabir Rasouli  William W. Hsieh  Alex J. Cannon 《Journal of Hydrology》2012

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Seismic damage evaluation in urban areas using the capacity spectrum method: Application to Barcelona   总被引：8，自引：0，他引：8  

Alex H. Barbat  Luis G. Pujades  Nieves Lantada 《Soil Dynamics and Earthquake Engineering》2008,28(10-11):851

Conceptual aspects related to seismic vulnerability, damage and risk evaluation are discussed first, together with a short review of the most widely used possibilities for seismic evaluation of structures. The capacity spectrum method and the way of obtaining seismic damage scenarios for urban areas starting from capacity and fragility curves are then discussed. The determination of capacity curves for buildings using non-linear structural analysis tools is then explained, together with a simplified expeditious procedure allowing the development of fragility curves. The seismic risk of the buildings of Barcelona, Spain, is analyzed in the paper, based on the application of the capacity spectrum method. The seismic hazard in the area of the city is described by means of the reduced 5% damped elastic response spectrum. The information on the buildings was obtained by collecting, arranging, improving and completing a broad database of the dwellings and current buildings. The buildings existing in Barcelona are mainly of two types: unreinforced masonry structures and reinforced concrete buildings with waffled-slab floors. The ArcView software was used to create a GIS tool for managing the collected information in order to develop seismic risk scenarios. This study shows that the vulnerability of the buildings is significant in Barcelona and, therefore, in spite of the low-to-moderate seismic hazard in the region, the expected seismic risk is considerable.  相似文献   

Spatio-temporal patterns of throughfall and solute deposition in an open tropical rain forest   总被引：4，自引：0，他引：4  

Alexander Zimmermann  Sonja Germer  Christopher Neill  Alex V. Krusche  Helmut Elsenbeer 《Journal of Hydrology》2008,360(1-4):87-102

The brief interaction of precipitation with a forest canopy can create a high spatial variability of both throughfall and solute deposition. We hypothesized that (i) the variability in natural forest systems is high but depends on system-inherent stability, (ii) the spatial variability of solute deposition shows seasonal dynamics depending on the increase in rainfall frequency, and (iii) spatial patterns persist only in the short-term. The study area in the north-western Brazilian state of Rondônia is subject to a climate with a distinct wet and dry season. We collected rain and throughfall on an event basis during the early wet season (n = 14) and peak of the wet season (n = 14) and analyzed the samples for pH and concentrations of , Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, , and DOC. The coefficient of variation for throughfall based on both sampling intervals was 29%, which is at the lower end of values reported from other tropical forest sites, but which is higher than in most temperate forests. Coefficients of variation of solute deposition ranged from 29% to 52%. This heterogeneity of solute deposition is neither particularly high nor particularly low compared with a range of tropical and temperate forest ecosystems. We observed an increase in solute deposition variability with the progressing wet season, which was explained by a negative correlation between heterogeneity of solute deposition and antecedent dry period. The temporal stability of throughfall patterns was low during the early wet season, but gained in stability as the wet season progressed. We suggest that rapid plant growth at the beginning of the rainy season is responsible for the lower stability, whereas less vegetative activity during the later rainy season might favor the higher persistence of “hot” and “cold” spots of throughfall quantities. The relatively high stability of throughfall patterns during later stages of the wet season may influence processes at the forest floor and in the soil. Solute deposition patterns showed less clear trends but all patterns displayed a short-term stability only. The weak stability of those patterns is apt to impede the formation of solute deposition-induced biochemical microhabitats in the soil.  相似文献