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Registros recuperados: 8
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A global inventory of small floating plastic debris ArchiMer
Van Sebille, Erik; Wilcox, Chris; Lebreton, Laurent; Maximenko, Nikolai; Hardesty, Britta Denise; Van Franeker, Jan A.; Eriksen, Marcus; Siegel, David; Galgani, Francois; Law, Kara Lavender.
Microplastic debris floating at the ocean surface can harm marine life. Understanding the severity of this harm requires knowledge of plastic abundance and distributions. Dozens of expeditions measuring microplastics have been carried out since the 1970s, but they have primarily focused on the North Atlantic and North Pacific accumulation zones, with much sparser coverage elsewhere. Here, we use the largest dataset of microplastic measurements assembled to date to assess the confidence we can have in global estimates of microplastic abundance and mass. We use a rigorous statistical framework to standardize a global dataset of plastic marine debris measured using surface-trawling plankton nets and coupled this with three different ocean circulation models...
Tipo: Text Palavras-chave: Marine debris; Ocean circulation; Model comparison.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00309/42053/41349.pdf
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CMIP5 Model Intercomparison of Freshwater Budget and Circulation in the North Atlantic ArchiMer
Deshayes, Julie; Curry, Ruth; Msadek, Rym.
The subpolar North Atlantic is a center of variability of ocean properties, wind stress curl, and air-sea exchanges. Observations and hindcast simulations suggest that from the early 1970s to the mid-1990s the subpolar gyre became fresher while the gyre and meridional circulations intensified. This is opposite to the relationship of freshening causing a weakened circulation, most often reproduced by climate models. The authors hypothesize that both these configurations exist but dominate on different time scales: a fresher subpolar gyre when the circulation is more intense, at interannual frequencies (configuration A), and a saltier subpolar gyre when the circulation is more intense, at longer periods (configuration B). Rather than going into the detail of...
Tipo: Text Palavras-chave: Atmosphere-ocean interaction; Freshwater; Climate models; Model comparison; Climate variability; North Atlantic Oscillation.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00199/31024/29429.pdf
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Comparison of breeding value prediction for two traits in a Nellore-Angus crossbred population using different Bayesian modeling methodologies Genet. Mol. Biol.
Hanna,Lauren L. Hulsman; Garrick,Dorian J.; Gill,Clare A.; Herring,Andy D.; Sanders,James O.; Riley,David G..
The objectives of this study were to 1) compare four models for breeding value prediction using genomic or pedigree information and 2) evaluate the impact of fixed effects that account for family structure. Comparisons were made in a Nellore-Angus population comprising F2, F3 and half-siblings to embryo transfer F2 calves with records for overall temperament at weaning (TEMP; n = 769) and Warner-Bratzler shear force (WBSF; n = 387). After quality control, there were 34,913 whole genome SNP markers remaining. Bayesian methods employed were BayesB ( π = 0.995 or 0.997 for WBSF or TEMP, respectively) and BayesC (π = 0 and π), where π is the ideal proportion of markers not included. Direct genomic values (DGV) from single trait Bayesian analyses were compared...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Bayesian inference; Crossbred cattle; Genomic prediction; Model comparison.
Ano: 2014 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572014000500005
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Differences and Congruencies between PVA Packages: the Importance of Sex Ratio for Predictions of Extinction Risk Ecology and Society
Brook, Barry W; Northern Territory University; barry.brook@ntu.edu.au; Burgman, Mark A; University of Melbourne; m.burgman@botany.unimelb.edu.au; Frankham, Richard; Macquarie University; rfrankha@rna.bio.mq.edu.au.
Population viability analysis (PVA) is used in conservation biology to predict extinction probabilities for threatened species. Previous studies have revealed large differences between the predictions of PVA modeling packages, but these comparisons included a range of nonstandard factors. A standardized comparison of five PVA packages (GAPPS, INMAT, RAMAS Metapop, RAMAS Stage, and VORTEX) was conducted on six examples (two mammals, two birds, one reptile, and a hypothetical bird/mammal-like life history). The individual-based packages (GAPPS and VORTEX) predicted a consistently higher risk of extinction than their matrix-based counterparts (INMAT and the RAMAS programs). This arose as only the former considered the effect of demographic stochasticity in...
Tipo: Peer-Reviewed Reports Palavras-chave: Demographic stochasticity; Extinction risk; Individual-based models; Matrix-based models; Model comparison; Parameter estimation; Population viability analysis; Sex ratio.
Ano: 2000
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Heuristic methods applied in reference evapotranspiration modeling Ciência e Agrotecnologia
Althoff,Daniel; Bazame,Helizani Couto; Filgueiras,Roberto; Dias,Santos Henrique Brant.
ABSTRACT The importance of the precise estimation of evapotranspiration is directly related to sustainable water usage. Since agriculture represents 70% of Brazil’s water consumption, adequate and efficient application of water may reduce the conflicts over the use of water among the multiple users. Considering the importance of accurate estimation of evapotranspiration, the objective of the present study was to model and compare the reference evapotranspiration from different heuristic methodologies. The standard Penman-Monteith method was used as reference for evapotranspiration, however, to evaluate the heuristic methodologies with scarce data, two widely known methods had their performances assessed in relation to Penman-Monteith. The methods used to...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Machine learning; Model comparison; Water management.
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542018000300314
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Modeling flocculation processes : intercomparison of a size class-based model and a distribution-based model ArchiMer
Maerz, Joeran; Verney, Romaric; Wirtz, Kai; Feudel, Ulrike.
Modeling suspended particulate matter (SPM) dynamics is essential to calculate sediment transport budgets and to provide relevant knowledge for the understanding of biogeochemical cycles in coastal waters. Natural flocs are characterized by their size, shape, structure and density that determine their settling velocity and therefore their vertical as well as horizontal transport. During transport, several processes, in particular aggregation and fragmentation, alter these particle properties. In the present study, we compare two different 0D modeling approaches for flocculation processes, a size class-based (SCB) model and a distribution-based (DB) model that follows the first moment of the particle distribution function. The study leads to an improved...
Tipo: Text Palavras-chave: Suspended particulate matter (SPM); Flocculation/aggregation; Size class-based model; Distribution-based model; Tidal dynamics; Model comparison.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00027/13870/11064.pdf
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Modeling Yield Risk Under Technological Change: Dynamic Yield Distributions and the U.S. Crop Insurance Program AgEcon
Zhu, Ying; Goodwin, Barry K.; Ghosh, Sujit K..
The objective of this study is to evaluate the risk associated with major agricultural commodity yields in the United States. We are particularly concerned with the nonstationary nature of the yield distribution, which arises primarily as a result of technological progress and changing environmental conditions over time. In contrast to common two-stage methods, we propose an alternative parametric model that allows the moments of yield distributions to change with time. Several model selection techniques suggest the proposed time-varying model outperforms more conventional models in terms of in-sample goodness-of-fit, out-of-sample predictive power, and the prediction accuracy of insurance premium rates.
Tipo: Journal Article Palavras-chave: Crop insurance; Model comparison; Time-varying distribution; Crop Production/Industries; Risk and Uncertainty.
Ano: 2011 URL: http://purl.umn.edu/105549
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The relative importance of environmental stochasticity, interspecific interactions, and observation error: Insights from sardine and anchovy landings ArchiMer
Hosack, Geoffrey R.; Trenkel, Verena; Dambacher, Jeffrey M..
Long-term time series of sardine and anchovy landings often suggest negative dependence between these species, and an array of mechanisms have been proposed as explanations. We reduce these propositions to four basic hypotheses of (1) independence, (2) correlated process noise, (3) interspecific interactions, and (4) correlated observational error. We use a Bayesian approach to develop priors for parsimonious state space models with both process noise and observation error that represent each of these hypotheses, and apply this approach to five long-term time series of landings collected from the Pacific and Atlantic Oceans. Model comparison criteria suggest that the hypothesis of correlated process noise has the broadest support, where the temporal...
Tipo: Text Palavras-chave: Adaptive Metropolis; Bayes factors; DIC; Gompertz model; Hyperstability; Kalman filter; Model comparison; Reactivity; Small pelagic fishes; Stability.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00159/27072/26066.pdf
Registros recuperados: 8
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