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Search Results: 1 - 7 of 7 matches for " Larramendy "
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Colas,M; Larramendy,Rocío; Merino,A;
Revista de Salud Animal , 2010,
Abstract: in order to study the histopathological changes caused by dispharynx nasuta in a cuban fine rooster, the animal was slaughtered by bleeding and cervical spinal section necropsied. the macroscopic detailed description of each organ and tissue was made. a piece of 1cm2 of proventriculus was conserved in formalin solution 10%, and the rest of proventricular duct was collected in sterile petri dish. it was evidenced, for the first time in our conditions, the microscopic morphological damage caused by a severe helminthiasis caused by d. nasuta on this type of host. the prevalence and intensity of parasitism were also calculated (100 and 4.0 %, respectively).
Stochastic models of the chemostat
Fabien Campillo,Marc Joannides,Irène Larramendy
Quantitative Biology , 2010,
Abstract: We consider the modeling of the dynamics of the chemostat at its very source. The chemostat is classically represented as a system of ordinary differential equations. Our goal is to establish a stochastic model that is valid at the scale immediately preceding the one corresponding to the deterministic model. At a microscopic scale we present a pure jump stochastic model that gives rise, at the macroscopic scale, to the ordinary differential equation model. At an intermediate scale, an approximation diffusion allows us to propose a model in the form of a system of stochastic differential equations. We expound the mechanism to switch from one model to another, together with the associated simulation procedures. We also describe the domain of validity of the different models.
Approximation of the Fokker-Planck equation of the stochastic chemostat
Fabien Campillo,Marc Joannides,Irène Larramendy-Valverde
Mathematics , 2011,
Abstract: We consider a stochastic model of the two-dimensional chemostat as a diffusion process for the concentration of substrate and the concentration of biomass. The model allows for the washout phenomenon: the disappearance of the biomass inside the chemostat. We establish the Fokker-Planck associated with this diffusion process, in particular we describe the boundary conditions that modelize the washout. We propose an adapted finite difference scheme for the approximation of the solution of the Fokker-Planck equation.
Estimation of the parameters of a stochastic logistic growth model
Fabien Campillo,Marc Joannides,Irène Larramendy-Valverde
Statistics , 2013,
Abstract: We consider a stochastic logistic growth model involving both birth and death rates in the drift and diffusion coefficients for which extinction eventually occurs almost surely. The associated complete Fokker-Planck equation describing the law of the process is established and studied. We then use its solution to build a likelihood function for the unknown model parameters, when discretely sampled data is available. The existing estimation methods need adaptation in order to deal with the extinction problem. We propose such adaptations, based on the particular form of the Fokker-Planck equation, and we evaluate their performances with numerical simulations. In the same time, we explore the identifiability of the parameters which is a crucial problem for the corresponding deterministic (noise free) model.
Erythrocytes modulate cell cycle progression but not the baseline frequency of sister chromatid exchanges in pig lymphocytes
Reigosa, Miguel A.;Soloneski, Sonia;Garcia, Carlos F.;Larramendy, Marcelo L.;
Brazilian Journal of Genetics , 1997, DOI: 10.1590/S0100-84551997000300007
Abstract: the effect of co-culturing varying concentrations of pig and human red blood cells (rbcs) on the baseline frequency of sister chromatid exchanges (sces) and cell-cycle progression in pig plasma (plcs) and whole blood leukocyte cultures (wbcs) was studied. no variation in sce frequency was observed between pig control wbc and plc. addition of pig and human rbcs to pig plcs did not modify the baseline frequency of sces. on the other hand, cell proliferation was slower in plcs than in wbcs. the addition of pig or human rbcs to plcs accelerated the cell-cycle progression of pig lymphocytes. when rbcs were added to plcs the concentration and time sequence of rbc incorporation affected the cell-cycle progression of swine lymphocytes. when doses of pig or human rbcs equivalent to those present in wbcs were added immediately after plc stimulation, the cell-cycle kinetics were similar to those of wbcs. shorter co-incubation periods or a reduction in the dose of rbcs made cell-cycle progression intermediate between plc and wbc values. thus, pig and human rbcs modulated the in vitro cell-cycle progression of pig lymphocytes in a time- and dose-dependent manner, and the low baseline frequency of sces of pig lymphocytes is independent of the presence or absence of erythrocytes in culture
Agroquímicos en Argentina: Genotoxicidad y citotoxicidad inducida por principios activos y sus formulaciones comerciales
Larramendy,Marcelo L; Molinari,Gabriela; González,Norma V; Pilili,Juan P; Candioti,Josefina Vera; Reigosa,Miguel A; Soloneski,Sonia;
BAG. Journal of basic and applied genetics , 2010,
Abstract: one of the major goals of our research laboratory is to evaluate comparatively the genotoxic and cytotoxic effects exerted by several pure agrochemicals and their technical formulations commonly used in argentina on vertebrate cells in vitro and in vivo. among them are listed the herbicides 2,4-d and 2,4-d dma?, dicamba and banvel?, the fungicide zineb and azzurro?, the insecticides carbofuran and furadan?, pirimicarb and aficida?, and the endectocide ivermectin and ivomec?. the sce, comet assay, micronuclei, chromosomal aberrations, cell-cycle progression, spindle disturbances, mtt and neutral red assays were used as end-points for geno and cytotoxicity. overall, the results clearly demonstrated that the damage induced by the commercial formulations is in general greater than that produced by the pure pesticides, suggesting the presence of deleterious components in the excipients with a toxic additive effect over the pure agrochemicals. accordingly, the results highlight that: 1) a complete knowledge of the toxic effect/s of the active ingredient is not enough in biomonitoring studies; 2) pesticide/s toxic effect/s should be evaluated according to the commercial formulation available in market; 3) the deleterious effect/s of the excipient/s present within the commercial formulation should not be either discarded nor underestimated, and 4) a single bioassay is not enough to characterize the toxicity of a agrochemical under study.
Rojas,P.Y; Rocío,Larramendy; Sánchez,I.Y; Mena,R.R; Neyra,R.D;
Revista de Salud Animal , 2009,
Abstract: the presence of the genus philophthalmus has been identify for first time in cuba from the physical examination of a semi rustic fowl in a guantanamo backyard. the animal was clinically explored and showed hyperemia on conjunctival and eyelid mucosa of both eyes together with the presence of 13 trematodes which were fixed in formalin-alcohol solution for morphometrical studies under stereoscope. the parasites showed morphometric characteristics compatible with philophthalmus sp. one of the helminth were macerated and eggs similar to those described for this genus were observed. this finding is the first notification of the agent in birds in cuba.
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