Does the timing of the spawning migration change for the southern component of the Northeast Atlantic Mackerel (Scomber scombrus,L. 1758)? An approximation using fishery analyses     

Antonio Punzón  Begoña Villamor 《Continental Shelf Research》2009,29(8):1195-1204

Part of the Northeast Atlantic mackerel population migrates towards the southern spawning area (Cantábrian Sea) at the end of winter. In this seasonal handline fishery targeting mackerel, the most important in the study area that targets this species, the timing of the peak of catches has shifted forward (later) in recent years. This paper presents results pointing to the likelihood that this shift is due to a change in the timing of the spawning migration to the southern area of the Northeast Atlantic mackerel population. Three types of fleet have been identified within this fishery, and in all of them there is a forward shift in time in effort exerted. Moreover, a new model has been defined for the standardization of catch per unit effort (CPUE). The fishing season appears to have shifted forward by 29 days between 2000 and 2006. Nevertheless, changes have been detected neither in the exploitation pattern nor in the duration of the fishing season during the period studied. A shift on this scale has important consequences for the management of the resource, the fleets that exploit it and the resource assessment survey designs that will have to be adapted to this new scenario.  相似文献   

Preface     

Pilar Queralt  John T. Weaver 《Surveys in Geophysics》2007,28(2-3):117-119

  相似文献   

Volcanic-sedimentary features in the Serra Geral Fm., Paraná Basin,southern Brazil: Examples of dynamic lava-sediment interactions in an arid setting     

Karla Petry  Dougal A. Jerram  Delia del Pilar M. de Almeida  Henrique Zerfass 《Journal of Volcanology and Geothermal Research》2007

The formation of volcanic–sedimentary interaction features in extreme arid environments is not a commonly described process. Specifically the occurrence of dynamically mixed sediments and juvenile igneous clasts as peperites, for water has been considered one major important factor in the processes of magma dismantling and mingling with unconsolidated sediment to form such deposits. The study area, located in south Brazil, shows a sequence of lava flows and intertrapic sandstone layers from the Paraná Basin, associated with the formation of clastic dykes, flow striations, peperite and ‘peperite-like’ breccias. Four processes are suggested for the genesis of the peperites: (a) fragmentation of the flow front and base; (b) sand injection; (c) dune collapse; (d) magma cascade downhill. The continued flow of a lava, while its outer crust is already cooling, causes it to break, especially in the front and base, fragments falling in the sand and getting mixed with it, generating the flow front ‘peperite-like’ breccia. The weight of the lava flow associated to shear stress at the base cause sand to be injected inwards the flow, forming injection clastic dykes in the cooled parts and injection peperite in the more plastic portions. The lava flow may partially erode the dune, causing the dune to collapse and forming the collapse ‘peperite-like’ breccia. The shear stress at the base of a flowing lava striates the unconsolidated sand, forming the flow striations. The sand that migrates over a cooled, jointed lava flow may get caught in the cavities and joints, forming the filling clastic dykes. These deposits are analogous to those found in the Etendeka, NW Namibia, and show that sediment–lava interactions in arid settings are widespread throughout the Paraná-Etendeka province during the onset of flood volcanism.  相似文献   

Fuzzy Logic Determination of Lithologies from Well Log Data: Application to the KTB Project Data set (Germany)     

David Bosch  Juanjo Ledo  Pilar Queralt 《Surveys in Geophysics》2013,34(4):413-439

Fuzzy logic has been used for lithology prediction with remarkable success. Several techniques such as fuzzy clustering or linguistic reasoning have proven to be useful for lithofacies determination. In this paper, a fuzzy inference methodology has been implemented as a MATLAB routine and applied for the first time to well log data from the German Continental Deep Drilling Program (KTB). The training of the fuzzy inference system is based on the analysis of the multi-class Matthews correlation coefficient computed for the classification matrix. For this particular data set, we have found that the best suited membership function type is the piecewise linear interpolation of the normalized histograms; that the best combination operator for obtaining the final lithology degrees of membership is the fuzzy gamma operator; and that all the available properties are relevant in the classification process. Results show that this fuzzy logic-based method is suited for rapidly and reasonably suggesting a lithology column from well log data, neatly identifying the main units and in some cases refining the classification, which can lead to a better interpretation. We have tested the trained system with synthetic data generated from property value distributions of the training data set to find that the differences in data distributions between both wells are significant enough to misdirect the inference process. However, a cross-validation analysis has revealed that, even with differences between data distributions and missing lithologies in the training data set, this fuzzy logic inference system is able to output a coherent classification.  相似文献   

Assessment of the physico-mechanical behaviour of gypsum-lime repair mortars as a function of curing time     

Jesús Igea Romera  Sagrario Martínez-Ramírez  Pilar Lapuente  María Teresa Blanco-Varela 《Environmental Earth Sciences》2013,70(4):1605-1618

Gypsum-based mortars were widely used during the Mudejar artistic period in Spain from the 12th to 16th century. During restoration works, compatibility between the new repair mortars and the original components is essential for an adequate intervention on the monument. The increasing interest of knowing the properties of the gypsum-lime-based mortars for restoration purposes justifies the research carried out. Different mortars compatible with traditional building materials were elaborated by varying the binder proportions, the type of aggregates, the binder/aggregate ratios and the curing time. The main goal of this paper is to characterize the mechanical behaviour and the pore structure of the mortars as a function of curing time. The influence between the different variables used to prepare the mortars and the development of the carbonation process over time is also considered. Mechanical strength and porosity measurements as well as X-ray diffraction and thermal analysis were performed after curing times of 1, 28 and 90 days. The results obtained confirmed a progressive increase in mechanical strength linked to the carbonation of the mortars prepared. Less lime binder and also aggregate contents showed the highest rise in strength over time, related to the highest initial porosity which favoured the carbon dioxide flow. The use of siliceous aggregates (GL-QS mortars) obtained the best results in the development of physico-mechanical properties over curing time. The knowledge obtained from the studied mortars provides practical information to establish a suitable mortar mixture for restoration works on historic buildings and modern architecture where gypsum-lime-based mortars are used.  相似文献   

Comment on González-Acebrón et al. Criteria for the recognition of localization and timing of multiple events of hydrothermal alteration in sandstones illustrated by petrographic, fluid inclusion, and isotopic analysis of the Tera Group, Northern Spain Int J Earth Sciences (2011) 100:1811–1826     

Antonio M. Casas  Pedro del Río  Pilar Mata  Juanjo Villalaín  Luis Barbero 《International Journal of Earth Sciences》2012,101(7):2043-2048

  相似文献   

An approach for valid covariance estimation via the Fourier series   总被引：1，自引：0，他引：1  

Pilar García-Soidán  Raquel Menezes  Óscar Rubiños-López 《Environmental Earth Sciences》2012,66(2):615-624

The use of kriging for construction of prediction or risk maps requires estimating the dependence structure of the random process, which can be addressed through the approximation of the covariance function. The nonparametric estimators used for the latter aim are not necessarily valid to solve the kriging system, since the positive-definiteness condition of the covariance estimator typically fails. The usage of a parametric covariance instead may be attractive at first because of its simplicity, although it may be affected by misspecification. An alternative is suggested in this paper to obtain a valid covariance from a nonparametric estimator through the Fourier series tool, which involves two issues: estimation of the Fourier coefficients and selection of the truncation point to determine the number of terms in the Fourier expansion. Numerical studies for simulated data have been conducted to illustrate the performance of this approach. In addition, an application to a real environmental data set is included, related to the presence of nitrate in groundwater in Beja District (Portugal), so that pollution maps of the region are generated by solving the kriging equations with the use of the Fourier series estimates of the covariance.  相似文献   

Land Use History and Site Formation Processes at the Punic Site of Pauli Stincus in West Central Sardinia     

Cristiano Nicosia  Roger Langohr  Pilar Carmona Gonzlez  Carlos Gmez Bellard  Emily B. Modrall  Jos Miguel Ruíz Prez  Peter van Dommelen 《Geoarchaeology》2013,28(4):373-393

The site of Pauli Stincus is located near the town of Terralba, on the inland shores of the Gulf of Oristano in west central Sardinia, Italy, and was occupied between the mid‐4th and the late 2nd century B.C. The site and its surroundings were the object of a joint archaeopedological and geomorphological study, which complemented the data from archaeological excavations. This study allowed us to evaluate the suitability of the different landscape and soil components for crop production in the Punic period. The discovery of a buried plow soil at the site's edge enabled us to identify a set of agricultural practices carried out by Punic farmers. These included the removal of sandy topsoil to cultivate deeper horizons enriched in illuvial clay, the use of a "sodbuster" or "rip ard," and the periodic burning of weeds, stubble, and other harvesting residues. The present study helped us to better understand the formation processes of the archaeological record at Pauli Stincus. Large quantities of allochtonous calcareous material were imported to the site from wet areas closer to the coast in order to produce earth‐based construction material, such as bricks and daub. © 2013 Wiley Periodicals, Inc.  相似文献   

Non‐Metabolic Uptake of Al3+ by Dead Leaves of Rubus ulmifolius: Comparison With Metabolic Bioaccumulation Data          下载免费PDF全文

Pablo Lodeiro  Marta López‐García  Luz Herrero  José L. Barriada  Roberto Herrero  Leticia Carro  Teresa Vilariño  Pilar Rodríguez  Manuel E. Sastre de Vicente 《洁净——土壤、空气、水》2016,44(2):154-161

  相似文献   

Erratum to: Fuzzy Logic Determination of Lithologies from Well Log Data: Application to the KTB Project Data set (Germany)     

David Bosch  Juanjo Ledo  Pilar Queralt 《Surveys in Geophysics》2014,35(2):479-481

  相似文献