Search results for "model."
showing 10 items of 23664 documents
Carvacrol activated biopolymeric foam: An effective packaging system to control the development of spoilage and pathogenic bacteria on sliced pumpkin…
2021
Abstract A commercial biodegradable starch-based polymer (Mater-Bi) was activated with carvacrol to develop a biodegradable and compostable polymer to be used in food packaging. Based on previous tests, carvacrol was added at 20 % weight of foam. MB foams, with and without carvacrol, were tested for their morphological characteristics, mechanical tests and kinetics of carvacrol release under refrigerated storage conditions. Carvacrol slightly increased the porosity of the foams, induced a reduction of the compressive elastic modulus (Ecom) of foamed MB from 6 to ∼ 3.4 MPa and a decrease of the tensile elastic modulus from ∼70 MPa to ∼16.5 MPa. Carvacrol release from the foam at 4 °C was alm…
Phylogenetic evidence for hybrid origins of asexual lineages in an aphid species
2003
International audience; Understanding the mode of origin of asexuality is central to ongoing debates concerning the evolution and maintenance of sexual reproduction in eukaryotes. This is because it has profound consequences for patterns of genetic diversity and ecological adaptability of asexual lineages, hence on the outcome of competition with sexual relatives both in short and longer terms. Among the possible routes to asexuality, hybridization is a very common mechanism in animals and plants. Aphids present frequent transitions from their ancestral reproductive mode (cyclical parthenogenesis) to permanent asexuality, but the mode of origin of asexual lineages is generally not known bec…
Transcriptome and proteome analysis of Pinctada margaritifera calcifying mantle and shell: focus on biomineralization
2010
Abstract Background The shell of the pearl-producing bivalve Pinctada margaritifera is composed of an organic cell-free matrix that plays a key role in the dynamic process of biologically-controlled biomineralization. In order to increase genomic resources and identify shell matrix proteins implicated in biomineralization in P. margaritifera, high-throughput Expressed Sequence Tag (EST) pyrosequencing was undertaken on the calcifying mantle, combined with a proteomic analysis of the shell. Results We report the functional analysis of 276 738 sequences, leading to the constitution of an unprecedented catalog of 82 P. margaritifera biomineralization-related mantle protein sequences. Component…
Molecular Bases for Sensitivity to Tubulin-Binding Herbicides in Green Foxtail
2004
Abstract We investigated the molecular bases for resistance to several classes of herbicides that bind tubulins in green foxtail (Setaria viridis L. Beauv.). We identified two α- and two β-tubulin genes in green foxtail. Sequence comparison between resistant and sensitive plants revealed two mutations, a leucine-to-phenylalanine change at position 136 and a threonine-to-isoleucine change at position 239, in the gene encoding α2-tubulin. Association of mutation at position 239 with herbicide resistance was demonstrated using near-isogenic lines derived from interspecific pairings between green foxtail and foxtail millet (Setaria italica L. Beauv.), and herbicide sensitivity bioassays combine…
When less means more: evolutionary and developmental hypotheses in rodent molars.
2012
10 pages; International audience; Tooth number in rodents is an example of reduction in evolution. All rodents have a toothless diastema lacking canine and most premolars present in most other mammals. Whereas some rodent lineages retained one premolar (p4), many others lost it during evolution. Recently, an 'inhibitory cascade' developmental model (IC) has been used to predict how the first molar (m1) influences the number and relative sizes of the following distal molars (m2 and m3). The model does not, however, consider the presence of premolars, and here we examine whether the premolar could influence and constrain molar proportions during development and evolution. By investigating a l…
Evolution of mammal tooth patterns: new insights from a developmental prediction model.
2009
14 pages.; International audience; The study of mammalian evolution is often based on insights into the evolution of teeth. Developmental studies may attempt to address the mechanisms that guide evolutionary changes. One example is the new developmental model proposed by Kavanagh et al. (2007), which provides a high-level testable model to predict mammalian tooth evolution. It is constructed on an inhibitory cascade model based on a dynamic balance of activators and inhibitors, regulating differences in molar size along the lower dental row. Nevertheless, molar sizes in some mammals differ from this inhibitory cascade model, in particular in voles. The aim of this study is to point out arvi…
Bayesian analysis improves experimental studies about temporal patterning of aggression in fish.
2017
Made available in DSpace on 2018-12-11T17:15:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-12-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) This study aims to describe a Bayesian Hierarchical Linear Model (HLM) approach for longitudinal designs in fish's experimental aggressive behavior studies as an alternative to classical methods In particular, we discuss the advantages of Bayesian analysis in dealing with combined variables, non-statistically significant results and required sample size using an experiment of angelfish (Pterophyllum scalare) species as case study. Groups of 3 individuals were subjected to daily observations recorded for 10 min durin…
Dynamical model identification of population of oysters for water quality monitoring
2014
International audience; The measurements of valve activity in a population of bivalves under natural environmental conditions (16 oysters in the Bay of Arcachon, France) are used for a physiological model identification. A nonlinear auto-regressive exogenous (NARX) model is designed and tested. The model takes into account the influence of environmental conditions using measurements of the sunlight intensity, the moonlight and tide levels. A possible influence of the internal circadian/circatidal clocks is also analyzed. Through this application, it is demonstrated that the developed dynamical model can be used for estimation of the normal physiological rhythms of permanently immersed oyste…
Empirical Bayes improves assessments of diversity and similarity when overdispersion prevails in taxonomic counts with no covariates
2019
Abstract The assessment of diversity and similarity is relevant in monitoring the status of ecosystems. The respective indicators are based on the taxonomic composition of biological communities of interest, currently estimated through the proportions computed from sampling multivariate counts. In this work we present a novel method to estimate the taxonomic composition able to work even with a single sample and no covariates, when data are affected by overdispersion. The presence of overdispersion in taxonomic counts may be the result of significant environmental factors which are often unobservable but influence communities. Following the empirical Bayes approach, we combine a Bayesian mo…
Efficient estimation of generalized linear latent variable models.
2019
Generalized linear latent variable models (GLLVM) are popular tools for modeling multivariate, correlated responses. Such data are often encountered, for instance, in ecological studies, where presence-absences, counts, or biomass of interacting species are collected from a set of sites. Until very recently, the main challenge in fitting GLLVMs has been the lack of computationally efficient estimation methods. For likelihood based estimation, several closed form approximations for the marginal likelihood of GLLVMs have been proposed, but their efficient implementations have been lacking in the literature. To fill this gap, we show in this paper how to obtain computationally convenient estim…