Multi-frequency electromagnetic method for inductive measurement of ground induced polarization and resistivity     

Carlos Alberto Dias  Hédison Kiuity Sato  Marcos Vitor Barbosa Machado  Olivar Antonio Lima de Lima 《Geophysical Prospecting》2019,67(1):210-225

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Ontogenetic shifts in feeding habits of orangemouth weakfish (Cynoscion xanthulus): From estuarine benthic feeder to marine nektivore top predator     

Víctor M. Muro-Torres  Felipe Amezcua  Lucinda Green  Jorge Payan  Eduardo F. Balart-Páez  Felipe Amezcua-Linares 《Marine Ecology》2023,44(1):e12735

Orangemouth weakfish is a highly important commercial and game fish species in the Tropical Eastern Pacific. However, studies assessing changes in its trophic ecology relevant to size, habitat (estuarine or marine), sex, and season are non-existent. We assessed its feeding habits and trophic position (TP) according to the aforementioned factors. Its dietary breadth was composed of 33 types of prey. The feeding habits and isotopic values (δ¹⁵N and δ¹³C) registered differences between sizes and habitat, indicating ontogenetic changes in habitat as well as TP, as small organisms (TP 3.1) inhabited the estuarine area, feeding on benthic and demersal organisms, whilst large individuals (TP 4.1) were found in the marine environment, preying on nektonic fauna. No differences were found according to sex or season. The isotopic niche showed that the different sizes of this species are generalist consumers with a clear separation between them and between habitats, as estuarine juvenile and preadult organisms have a larger isotopic niche than adult marine organisms, being an opportunist tertiary estuarine consumers during their early stages, and a top marine predator during the adult phase.  相似文献   

Planform dynamics of the Iquitos anabranching structure in the Peruvian Upper Amazon River          下载免费PDF全文

Alejandro Mendoza  Jorge D. Abad  Christian E. Frias  Collin Ortals  Jorge Paredes  Hugo Montoro  Jorge Vizcarra  Cesar Simon  Gabriel Soto‐Cortés 《地球表面变化过程与地形》2016,41(7):961-970

The upper reach of the Amazon River has a very dynamic morphology, with the highest rates of migration observed in the entire Amazon River. It has an anabranching channel pattern which alternates between a condition of single channel and anabranching structures; in particular, the anabranching structure near Iquitos City shows an interesting channel behavior. Its channels migrate at different rates, where there are processes of narrowing and widening, and also collision and development of new channels. The temporal evolution of the Iquitos anabranching structure is described during the period from 1985 to 2014. The study is carried out by using satellite images to track the migration patterns, which are contrasted to the underlying geological units in the valley. Bathymetry of the structure and several velocity transects were obtained during a field campaign prior to the 2012 historic flood event. This information allowed for numerical modeling in order to compute the hydrodynamic flow field that complements the temporal analysis, aiming to understand the planform migration patterns after the 2012 flood event. It is observed that the geological units play an important role in modulating the migration rates and planform development of the channels. The channels in the structure are in contention to be the main channel, which become the secondary channel after migration. This causes the channels to experience a rise in bed elevation and narrowing of the channel itself; if this trend continues for several more years, these channels will detach from the Iquitos anabranching structure, thus forming paleo‐channels. This geomorphic process is important for horizontal and vertical soil heterogeneity along the floodplain. In general, the analysis shows a complex interaction between the underlying geological units, flow structure, morphology of the bed and planform migration. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Reconstructing 800 years of historical eruptive activity at Popocatépetl Volcano,Mexico     

Ana Lillian Martin-Del Pozzo  Alan Rodríguez  Jorge Portocarrero 《Bulletin of Volcanology》2016,78(3):18

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Earth’s Rotation: A Challenging Problem in Mathematics and Physics     

José M. Ferrándiz  Juan F. Navarro  Alberto Escapa  Juan Getino 《Pure and Applied Geophysics》2015,172(1):57-74

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Use of terrestrial photogrammetry based on structure‐from‐motion for mass balance estimation of a small glacier in the Italian alps          下载免费PDF全文

Livia Piermattei  Luca Carturan  Alberto Guarnieri 《地球表面变化过程与地形》2015,40(13):1791-1802

Different high‐resolution techniques can be employed to obtain information about the three‐dimensional (3D) surface of glaciers. This is typically carried out using efficient, but also expensive and logistically demanding, light detection and ranging (LiDAR) technologies, such as airborne scanners and terrestrial laser scanners. Recent technological improvements in the field of image analysis and computer vision have prompted the development of a low‐cost photogrammetric approach, which is referred to as ‘structure‐from‐motion’ (SfM). Combined with dense image‐matching algorithms, this method has become competitive for the production of high‐quality 3D models. However, several issues typical of this approach should be considered for application in glacial environments. In particular, the surface morphology, the different substrata, the occurrence of sharp contrast from solar shadows and the variable distance from the camera positions can negatively affect the image texture, and reduce the possibility of obtaining a reliable point cloud from the images. The objective of this study is to test the structure‐from‐motion multi view stereo (SfM‐MVS) approach in a small debris‐covered glacier located in the eastern Italian Alps, using a consumer‐grade reflex camera and the computer vision‐based software PhotoScan. The quality of the 3D models produced by the SfM‐MVS process was assessed via the comparison with digital terrain models obtained from terrestrial laser scanning (TLS) surveys that were performed at the same epochs. The effect of different terrain gradients and different substrata (debris, snow and firn) was also evaluated in terms of the accuracy of the reconstruction by SfM‐MVS versus TLS. Our results show that the quality of this new photogrammetric approach is similar to the quality of TLS and that point cloud densities are comparable or even higher compared with TLS. However, special care should be taken while planning the SfM survey geometry, to optimize the 3D model quality and spatial coverage. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Completeness assessment of earthquake catalogues under uncertain knowledge     

Jorge L. Alamilla  Rossana Vai  Luis Esteva 《Journal of Seismology》2015,19(1):27-40

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Discriminating Between Different Streamflow Regimes by Using the Fisher-Shan Method: An Application to the Colombia Rivers     

Jorge O. Pierini  Juan C. Restrepo  Michele Lovallo  Luciano Telesca 《Acta Geophysica》2015,63(2):533-546

The Fisher-Shannon (FS) information plane, defined by the Fisher information measure (FIM) and the Shannon entropy power (N_X), was robustly used to investigate the complex dynamics of eight monthly streamflow time series in Colombia. In the FS plane the streamflow series seem to aggregate into two different clusters corresponding to two different climatological regimes in Colombia. Our findings suggest the use of the statistical quantity defined by the FS information plane as a tool to discriminate among different hydrological regimes.  相似文献   

Identification of activity areas by soil phosphorus and organic matter analysis in two rooms of the Iberian Sanctuary “Cerro El Pajarillo”     

Alberto Snchez Vizcaíno  María L. Caabate 《Geoarchaeology》1999,14(1):47-62

This article shows the results obtained from our research on two rooms of the 4th century B.C. Iberian sanctuary “Cerro El Pajarillo” in Huelma (province of Jaén, southern Spain). Our research method combines traditional archaeological procedures with analysis of chemical markers, in particular, analysis of phosphorus and organic matter in samples of soil taken from the floor of the rooms. These analyses help identify two activity areas: one related to storage, and another to food consumption and refuse. © 1999 John Wiley & Sons, Inc.  相似文献   

Soil hydraulic conductivities of latosols under pasture,forest and teak in Rondonia,Brazil     

Helmut Elsenbeer  Bradley E. Newton  Thomas Dunne  Jorge M. de Moraes 《水文研究》1999,13(9):1417-1422

We investigated the changes of saturated hydraulic conductivity, K_sat , with depth of latosols developed on Precambrian basement rocks under primary rainforest, pasture and teak. In all cases, K_sat decreased with depth, with most of the decrease occurring between the surface and a depth of 30 cm. In conjunction with prevailing rainfall intensities and frequencies, this anisotropy supports a pronounced lateral component of hillslope flow paths, and also of overland flow under pasture. Our results are at variance with data from other latosols where K_sat tends to increase with depth, and hence suggest that considerable restraint is needed in generalization and extrapolation until results from a co‐ordinated effort at hydrology‐oriented data collection become available. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献