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Search Results: 1 - 10 of 960 matches for " Laure Corbari "
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Oxygen as a Driver of Early Arthropod Micro-Benthos Evolution
Mark Williams, Jean Vannier, Laure Corbari, Jean-Charles Massabuau
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0028183
Abstract: Background We examine the physiological and lifestyle adaptations which facilitated the emergence of ostracods as the numerically dominant Phanerozoic bivalve arthropod micro-benthos. Methodology/Principal Findings The PO2 of modern normoxic seawater is 21 kPa (air-equilibrated water), a level that would cause cellular damage if found in the tissues of ostracods and much other marine fauna. The PO2 of most aquatic breathers at the cellular level is much lower, between 1 and 3 kPa. Ostracods avoid oxygen toxicity by migrating to waters which are hypoxic, or by developing metabolisms which generate high consumption of O2. Interrogation of the Cambrian record of bivalve arthropod micro-benthos suggests a strong control on ecosystem evolution exerted by changing seawater O2 levels. The PO2 of air-equilibrated Cambrian-seawater is predicted to have varied between 10 and 30 kPa. Three groups of marine shelf-dwelling bivalve arthropods adopted different responses to Cambrian seawater O2. Bradoriida evolved cardiovascular systems that favoured colonization of oxygenated marine waters. Their biodiversity declined during intervals associated with black shale deposition and marine shelf anoxia and their diversity may also have been curtailed by elevated late Cambrian (Furongian) oxygen-levels that increased the PO2 gradient between seawater and bradoriid tissues. Phosphatocopida responded to Cambrian anoxia differently, reaching their peak during widespread seabed dysoxia of the SPICE event. They lacked a cardiovascular system and appear to have been adapted to seawater hypoxia. As latest Cambrian marine shelf waters became well oxygenated, phosphatocopids went extinct. Changing seawater oxygen-levels and the demise of much of the seabed bradoriid micro-benthos favoured a third group of arthropod micro-benthos, the ostracods. These animals adopted lifestyles that made them tolerant of changes in seawater O2. Ostracods became the numerically dominant arthropod micro-benthos of the Phanerozoic. Conclusions/Significance Our work has implications from an evolutionary context for understanding how oxygen-level in marine ecosystems drives behaviour.
Exploration of the Deep-Sea Fauna of Papua New Guinea
Eric Pante,Laure Corbari,Justine Thubaut,Tin-Yam Chan
Oceanography , 2012,
Abstract: Little is known of New Guinea's deep benthic communities. In fall 2010, the Muséum national d'Histoire naturelle, Institut de Recherche pour le Développement, and University of Papua New Guinea spearheaded an international three-leg cruise, BioPapua, aimed at exploring the deep waters of eastern Papua New Guinea and its satellite islands. Special attention was given to faunal assemblages associated with sunken wood and decomposing vegetation as well as seamount summits and slopes. In this article, we review the information available on the deep ecosystems of Papua New Guinea and summarize preliminary results of the BioPapua cruise.
Integrative Biology of Idas iwaotakii (Habe, 1958), a ‘Model Species’ Associated with Sunken Organic Substrates
Justine Thubaut, Laure Corbari, Olivier Gros, Sébastien Duperron, Arnaud Couloux, Sarah Samadi
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069680
Abstract: The giant bathymodioline mussels from vents have been studied as models to understand the adaptation of organisms to deep-sea chemosynthetic environments. These mussels are closely related to minute mussels associated to organic remains decaying on the deep-sea floor. Whereas biological data accumulate for the giant mussels, the small mussels remain poorly studied. Despite this lack of data for species living on organic remains it has been hypothesized that during evolution, contrary to their relatives from vents or seeps, they did not acquire highly specialized biological features. We aim at testing this hypothesis by providing new biological data for species associated with organic falls. Within Bathymodiolinae a close phylogenetic relationship was revealed between the Bathymodiolus sensu stricto lineage (i.e. “thermophilus” lineage) which includes exclusively vent and seep species, and a diversified lineage of small mussels, attributed to the genus Idas, that includes mostly species from organic falls. We selected Idas iwaotakii (Habe, 1958) from this latter lineage to analyse population structure and to document biological features. Mitochondrial and nuclear markers reveal a north-south genetic structure at an oceanic scale in the Western Pacific but no structure was revealed at a regional scale or as correlated with the kind of substrate or depth. The morphology of larval shells suggests substantial dispersal abilities. Nutritional features were assessed by examining bacterial diversity coupled by a microscopic analysis of the digestive tract. Molecular data demonstrated the presence of sulphur-oxidizing bacteria resembling those identified in other Bathymodiolinae. In contrast with most Bathymodiolus s.s. species the digestive tract of I. iwaotakii is not reduced. Combining data from literature with the present data shows that most of the important biological features are shared between Bathymodiolus s.s. species and its sister-lineage. However Bathymodiolus s.s. species are ecologically more restricted and also display a lower species richness than Idas species.
Pensamentos e cren as a respeito do uso e do ensino das línguas faladas na localidade paranaense de Irati Pensamentos e cren as a respeito do uso e do ensino das línguas faladas na localidade paranaense de Irati
Clarice Cristina CORBARI
Entrepalavras : Revista de Linguística do Departamento de Letras Vernáculas da UFC , 2012,
Abstract: This article presents partial results of research on linguistic beliefs and attitudes expressed by speakers from Irati, a city in Paraná that presents a complex sociolinguistic scenario. As guidelines for this study, we used the theoretical and methodological principles of Sociology of Language, Sociolinguistics and Social Psychology concerning the analysis of linguistic beliefs and attitudes. The corpus comes from the Project Cren as e atitudes linguísticas: um estudo da rela o do português com línguas de contato (AGUILERA, 2009). From the questionnaire of 48 questions, applied to eighteen respondents, we selected seven questions that reveal thoughts and beliefs about the speakers’ linguistic behavior and the teaching of the languages spoken in the town. The results showed, in general, an attitude of openness in relation to the cultivation heritage languages, both in the institutional sphere (school and the church) and in the sphere of everyday interactions. Este artigo apresenta resultados parciais de pesquisa sobre cren as e atitudes linguísticas manifestas por falantes de Irati, município paranaense que se caracteriza por apresentar um cenário sociolinguístico complexo. Para nortear este estudo, s o utilizados princípios teórico-metodológicos da Sociologia da Linguagem, da Sociolinguística e da Psicologia Social referentes à análise de cren as e atitudes linguísticas. O corpus foi coletado por meio do projeto Cren as e atitudes linguísticas: um estudo da rela o do português com línguas de contato (AGUILERA, 2009). Do questionário de 48 perguntas, aplicados a dezoito entrevistados, foram selecionadas, para este trabalho, sete perguntas que revelam pensamentos e cren as a respeito do comportamento linguístico dos falantes e do ensino das línguas faladas na localidade. Os resultados mostraram, de modo geral, uma atitude de abertura em rela o ao cultivo das línguas de heran a, tanto no ambito institucional (escola e igreja) como no ambito das intera es cotidianas.
Efeitos da Lei de Responsabilidade Fiscal no endividamento dos Municípios Brasileiros: uma análise de dados em painéis
Macedo, Joel de Jesus;Corbari, Ely Célia;
Revista Contabilidade & Finan?as , 2009, DOI: 10.1590/S1519-70772009000300004
Abstract: this study aims to analyze whether the brazilian lrf - lei de responsabilidade fiscal (fiscal responsibility law), as a mechanism of fiscal restraint, has influenced the debt pattern of cities with more than 100,000 inhabitants, covering the period from 1998 to 2006. in order to reach this goal, two econometric models were built, and the ordinary least squares (ols) method was used for the calculations. the statistical technique used was the balanced panel data. the first econometric model was used to examine whether there were any alterations in the influence of the financial management variables on debt over time, with the insertion of time dummy variables. the results showed that, in the analyzed period, there was a change in the debt pattern as demonstrated by the variables 'outdated debt' and 'capital structure'. the second econometric model was used to examine whether the alteration of the influence of the financial management variables on debt over time was related to the introduction of the lrf, with the insertion of lrf rule dummies. the results show that, after the introduction of the lrf, the 'outdated debt' suffered loss of explanatory power, while the variable 'capital structure' got increased explanatory power, suggesting that the management of debt and funding sources has become more effective, and debt rollover is no longer a common practice in the municipalities. the results are highly significant, both in relation to the relevance of the selected indicators and the impact of the lrf, confirming the hypothesis guiding this research that the debt of the municipalities was influenced by the lrf.
Elevation based correction of snow coverage retrieved from satellite images to improve model calibration
C. Corbari, G. Ravazzani, J. Martinelli,M. Mancini
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2009,
Abstract: The most widely used method for snow dynamic simulation relies on temperature index approach, that makes snow melt and accumulation processes depend on air temperature related parameters. A recently used approach to calibrate these parameters is to compare model results with snow coverage retrieved from satellite images. In area with complex topography and heterogeneous land cover, snow coverage may be affected by the presence of shaded area or dense forest that make pixels to be falsely classified as uncovered. These circumstances may have, in turn, an influence on calibration of model parameters. In this paper we propose a simple procedure to correct snow coverage retrieved from satellite images. We show that using raw snow coverage to calibrate snow model may lead to parameter values out of the range accepted by literature, so that the timing of snow dynamics measured at two ground stations is not correctly simulated. Moreover, when the snow model is implemented into a continuous distributed hydrological model, we show that calibration against corrected snow coverage reduces the error in the simulation of river flow in an Alpine catchment.
Land surface temperature representativeness in a heterogeneous area through a distributed energy-water balance model and remote sensing data
C. Corbari, J. A. Sobrino, M. Mancini,V. Hidalgo
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2010,
Abstract: Land surface temperature is the link between soil-vegetation-atmosphere fluxes and soil water content through the energy water balance. This paper analyses the representativeness of land surface temperature (LST) for a distributed hydrological water balance model (FEST-EWB) using LST from AHS (airborne hyperspectral scanner), with a spatial resolution between 2–4 m, LST from MODIS, with a spatial resolution of 1000 m, and thermal infrared radiometric ground measurements that are compared with the representative equilibrium temperature that closes the energy balance equation in the distributed hydrological model. Diurnal and nocturnal images are analyzed due to the non stable behaviour of the thermodynamic temperature and to the non linear effects induced by spatial heterogeneity. Spatial autocorrelation and scale of fluctuation of land surface temperature from FEST-EWB and AHS are analysed at different aggregation areas to better understand the scale of representativeness of land surface temperature in a hydrological process. The study site is the agricultural area of Barrax (Spain) that is a heterogeneous area with a patchwork of irrigated and non irrigated vegetated fields and bare soil. The used data set was collected during a field campaign from 10 to 15 July 2005 in the framework of the SEN2FLEX project.
Land surface temperature representativeness in a heterogeneous area through a distributed energy-water balance model and remote sensing data
C. Corbari,J. A. Sobrino,M. Mancini,V. Hidalgo
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2010, DOI: 10.5194/hess-14-2141-2010
Abstract: Land surface temperature is the link between soil-vegetation-atmosphere fluxes and soil water content through the energy water balance. This paper analyses the representativeness of land surface temperature (LST) for a distributed hydrological water balance model (FEST-EWB) using LST from AHS (airborne hyperspectral scanner), with a spatial resolution between 2–4 m, LST from MODIS, with a spatial resolution of 1000 m, and thermal infrared radiometric ground measurements that are compared with the representative equilibrium temperature that closes the energy balance equation in the distributed hydrological model. Diurnal and nocturnal images are analyzed due to the non stable behaviour of the thermodynamic temperature and to the non linear effects induced by spatial heterogeneity. Spatial autocorrelation and scale of fluctuation of land surface temperature from FEST-EWB and AHS are analysed at different aggregation areas to better understand the scale of representativeness of land surface temperature in a hydrological process. The study site is the agricultural area of Barrax (Spain) that is a heterogeneous area with a patchwork of irrigated and non irrigated vegetated fields and bare soil. The used data set was collected during a field campaign from 10 to 15 July 2005 in the framework of the SEN2FLEX project.
Snow satellite images for calibration of snow dynamic in a continuous distributed hydrological model
C. Corbari,J. Martinelli,G. Ravazzani,M. Mancini
Hydrology and Earth System Sciences Discussions , 2007,
Abstract: The snow accumulation and melt processes are well known to play an important role on the river flow regime, in particular this is enhanced for basin with complex topography where the snow dynamic is strongly affected by hillslope exposition. This paper presents a simplified numerical model for snow dynamic simulation based on air temperature thresholds that rule the snow melt and accumulation processes implemented into a continuous distributed hydrological model for hydrograph simulations at basin scale. The possibility to calibrate these temperature thresholds from snow cover maps derived from NOAA satellite images is discussed. Snow covered pixels are classified according to a procedure based on aspect and elevation of each pixel, that allows to identify snow covered pixels also in shadowed areas. Snow model performance is proved at local and basin scale. The former shows a good agreement between modelled snow dynamic and observed snow height data at the Antrona station in the Toce basin; the latter shows agreement between observed and simulated hydrographs for the three gauge stations of Toce, Ticino and Maggia rivers.
Assessing snow water equivalent of an Alpine catchment using snow dynamic model calibrated with satellite images
C. Corbari,G. Ravazzani,J. Martinelli,M. Mancini
Hydrology and Earth System Sciences Discussions , 2008,
Abstract: This paper presents a simplified numerical model of snow dynamic implemented into a continuous distributed hydrological model for hydrograph simulations at basin scale. This snow model is based on air temperature thresholds that rule the snow melt and accumulation processes. A procedure to calibrate these temperature thresholds from NOAA satellite snow cover maps is discussed. We show that, for an accurate model calibration from satellite images, it is necessary to consider the presence of areas with complex topography such as mountain slopes. Snow model performance is tested both at local and basin scale on Alpine catchment. At local scale a good agreement between modelled snow dynamic and observed snow height data at snow gauge stations in the river Anza basin (Italy) is shown; at basin scale agreement between observed and simulated hydrographs at the discharge station of river Toce (Italy) is reported.
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