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Search Results: 1 - 10 of 200662 matches for " P Grimaud "
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Herbage mineral nutrition indexed as tools for rapid mineral status diagnosis in tropical pastures
P Grimaud, P Thomas, V Blanfort, P Lecomte
African Crop Science Journal , 2007,
Abstract: The animal production sector in the tropics is increasingly becoming challenged with the limited availability of pastures. There is need therefore to explore other options to suppliment the available pastures. The objectives of this study therefore was to understand how herbage mineral dilution indices used in developed countries as tools for controlled fertilisation, could be adapted in a tropical environment where high seasonal variations with regard to availability occur in pastures. A 3-year study was carried out in La Réunion Island, Indian Ocean. Forty nine farms, with swards made of either temperate or tropical grasses, grazed or mowed, were visited between four and five times a year. Dry biomass and dry matter contents were reported at each sample collection; whereas mineral indices were calculated from chemical analysis with a view to generate relevant fertilisation recommendations. Although the dry matter ( DM) values of less than 20% indicated a better stage of exploitation for the grasses, the data consistently indicate a decrease in the seasonal differences of dry biomass for grazed species. The use of indices, which combine both plant mineral status and pasture biomass, appeared relevant indicators for farmers and for pasture experts in tropical countries, and can be predicted through near infrared spectroscopy with an acceptable precision (R2 = 0.80, 0.60 and 0.91, for nitrogen , phosphorous and potassium, respectively). With reduced cost of pasture feed analysis using the NIRS, farmers can be able to make informed decisions based on scientific data. Fertilisation is one of the potential options to improve pasture management as indicated by findings of this study. This is useful evidence-based information that could be incorporated in extension packages and resource materials for dissemination and subsequent adoption by livestock farming communities to improve produtivity.
Facteurs de variation du poids vif et de l’état corporel du zébu Arabe en zone soudanienne du Tchad
A Béchir, P Grimaud, C Kaboré-Zoungrana
Sciences & Nature , 2010,
Abstract: L’objectif de cette étude a été de déterminer les effets saisonniers sur l’évolution du poids et de la note d’état corporel (NEC) des zébus arabes du Tchad. Durant les cinq saisons liées au calendrier fourrager, des mensurations et des notations d’état corporel ont été effectuées sur des bovins males et femelles. Les mesures barymétriques ont concerné le périmètre thoracique. La NEC a été déterminée par palpation de la région lombaire de l’animal. L’alternance saisonnière a provoqué de grandes variations de poids et de l’état corporel des animaux qui ont été notées selon le sexe et l’age. La variabilité des performances pondérales (2,2 ± 16 kg à 64 ±24 kg) et d’état corporel des animaux, obtenue à partir des facteurs individuels (sexe ou age) et saisonniers (disponibilité fourragère), a montré que ce sont les animaux d’age supérieur à 6 ans qui ont perdu plus de poids en saison sèche. Les femelles de 3-6 ans (64 ± 44,8 kg) et les males de 2-3 ans (54 ± 43 kg) ont montré les fluctuations pondérales les plus significatives en saison des pluies. Afin de minimiser les risques et maximiser la production en élevage extensif, des améliorations dans la conduite des animaux ont été proposées. Mots clés : Variations fourragères - Poids - Etat corporel - Zébu arabe - Tchad
Les coulisses du sublime Behind the scenes of the sublimeMovie stunts, machinery, special effects
Emmanuel Grimaud
Ateliers d'Anthropologie , 2011, DOI: 10.4000/ateliers.8830
Abstract: Toute cascade de cinéma peut être per ue comme une configuration expérimentale posant au spectateur un problème d’attribution. Le cinéma livre en effet depuis ses origines une course frénétique pour rendre visuellement plausibles des actions physiquement impossibles en camouflant leurs conditions de réalisation. Qui est à l’origine de quoi ? Y a-t-il procédé et lequel ? L’acteur était-il soutenu par des machines ou par des cables ? A-t-il effectué la cascade lui-même ? etc. Or l’acte impossible que le plateau prétend réaliser n’est jamais simplement attribuable à l’acteur, aux techniciens ou à la caméra. Il n’est jamais non plus complètement réductible à du trucage. à la fois de l’ordre de la performance physique (mais pas uniquement), un brin machinique, en grande partie collective (ou distribuée), l’effet de virtuosité au cinéma reste par ailleurs toujours inachevé sans la perception d’un spectateur pour donner à la cascade sa continuité finale. En examinant comment les cascades se font, camouflent et confondent le spectateur sur leurs sources et leur processus, cet article explore les enjeux de cette virtuosité hybride et compliquée qui arrache de fa on optique l’acte à ses conditions matérielles d’exécution. Cinema is engaged from its origins in a frantic race to make physically impossible actions visually plausible by camouflaging their conditions of application. Who is at the origin of what? Is there a method and which one? Was the actor supported by machines or by cables? Did he perform the stunt himself? etc. But the impossible act which the set contends to achieve is never simply due to the actor, the technicians or the camera. It is also never completely reducible to special effects. Both physical performance (but not only), a strand machinic and largely collective (or distributed), the effect of virtuosity in movies is also still incomplete without the perception of an audience who gives a final continuity to the stunt. By examining how stunts are done, camouflaged and how they confuse the viewer on their sources and processes, this article explores the challenges of this hybrid and complicated virtuosity that takes the optically act away from its material conditions of performance.
Cell-matrix interactions in Schistosomal portal fibrosis: a dynamic event
Grimaud, Jean-Alexis;
Memórias do Instituto Oswaldo Cruz , 1987, DOI: 10.1590/S0074-02761987000800010
Abstract: in recent years, one of the most significant progress in the understanding of liver diseases was the demonstration that liver fibrosis is a dynamic process resulting from a balance between synthesis and degradation of several matrix components, collagen in particular. thus, fibrosis has been found to be a very early event during liver diseases, be it of toxic, viral or parasitic origin, and to be spontaneously reversible, either partially or totally. in liver fibrosis cell matrix interactions are dependent on the existence of the many factors (sometimes acting in combination) which produce the same events at the cellular and molecular levels. these events are: (i) the recruitment of fiber-producing cells, (ii) their proliferation, (iii) the secretion of matrix constituents of the extracellular matrix, and (iv) the remodeling and degradation of the newly formed matrix. all these events represent, at least in principle, a target for a therapeutic intervention aimed at influencing the experimentally induced hepatic fibrosis. in this context, hepatosplenic schistosomiasis is of particular interest, being an immune cell-mediated granulomatous disease and a model of liver fibrosis allowing extensive studies in human and animals as well as providing original in vitro models.
Multimethod characterization of the French Pyrenean valley of Bagnères-de-Bigorre for seismic hazard evaluation: observations and models
Annie Souriau,Emmanuel Chaljub,Cécile Cornou,Ludovic Margerin,Marie Calvet,Julie Maury,Marc Wathelet,Franck Grimaud,Christrian Ponsolles,Catherine Péquegnat,Mickael Langlais,Philippe Gueguen
Physics , 2012, DOI: 0120100293
Abstract: A narrow rectilinear valley in the French Pyrenees, affected in the past by damaging earthquakes, has been chosen as a test site for soil response characterization. The main purpose of this initiative was to compare experimental and numerical approaches. A temporary network of 10 stations has been deployed along and across the valley during two years; parallel various experiments have been conducted, in particular ambient noise recording, and seismic profiles with active sources for structure determination at the 10 sites. Classical observables have been measured for site amplification evaluation, such as spectral ratios of horizontal or vertical motions between site and reference stations using direct S waves and S coda, and spectral ratios between horizontal and vertical (H/V) motions at single stations using noise and S-coda records. Vertical shear-velocity profiles at the stations have first been obtained from a joint inversion of Rayleigh wave dispersion curves and ellipticity. They have subsequently been used to model the H/V spectral ratios of noise data from synthetic seismograms, the H/V ratio of S-coda waves based on equipartition theory, and the 3D seismic response of the basin using the spectral element method. General good agreement is found between simulations and observations. The 3D simulation reveals that topography has a much lower contribution to site effects than sedimentary filling, except at the narrow ridge crests. We find clear evidence of a basin edge effect, with an increase of the amplitude of ground motion at some distance from the edge inside the basin and a decrease immediately at the slope foot.
Chronic murine myocarditis due to Trypanosoma cruzi: an ultrastructural study and immunochemical characterization of cardiac interstitial matrix
Andrade, Sonia G.;Grimaud, Jean Alexis;
Memórias do Instituto Oswaldo Cruz , 1986, DOI: 10.1590/S0074-02761986000100004
Abstract: in an attempt to define the mouse-model for chronic chagas' disease, a serological, histopathological and ultrastructural study as well as immunotyping of myocardium collagenic matrix were performed on swiss mice, chronically infected with trypanosoma cruzi strains: 21 sf and mambaí (type ii); pmn and bolivia (type iii), spontaneously surviving after 154 to 468 days of infection. haemagglutination and indirect immunofluorescence tests showed high titres of specific antibodies. the ultrastructural study disclosed the cellular constitution of the inflammatory infiltrate showing the predominance of monocytes, macrophages with intense phagocytic activity, fibroblasts, myofibroblasts and abundant collagen matrix suggesting the association of the inflammatory process with fibrogenesis in chronic chagasic cardiomyopathy. artertolar and blood capillary alterations together with dissociation of cardiac cells from the capillary wall by edema and inflammation were related to ultrastructural lesions of myocardial cells. rupture of parasitized cardiac myocells contribute to intensify the inflammatory process in focal areas. collagen immunotyping showed the predominance of types iii and iv collagen. collagen degradation and phagocytosis were present suggesting a reversibility of the fibrous process. the mouse model seems to be valuable in the study of the pathogenetic mechanisms in chagas cardiomyopathy, providing that t. cruzi strains of low virulence and high pathogenecity are used.
Emmanuel Grimaud,Victor A. Stoichita,Graham Jones
Ateliers du LESC , 2011, DOI: 10.4000/ateliers.8838
Abstract: Courses à la virtuositéNombreuses sont les pratiques qui ont généré, parfois en leur c ur et souvent en leurs marges, des programmes acrobatiques. Ces programmes ont généralement des finalités comparables. Il s’agit d’apprécier et d’évaluer l’excellence technique, d’explorer plus ou moins librement les possibilités d’un instrument ou de mettre à l’épreuve ses limites. De la musique à la jonglerie, de la prestidigitation à la voltige aérienne ou encore à la cascade à moto, rares sont les arts ...
A Low-Footprint Class Loading Mechanism for Embedded Java Virtual Machines
Christophe Rippert,Alexandre Courbot,Gilles Grimaud
Computer Science , 2006,
Abstract: This paper shows that it is possible to dramatically reduce the memory consumption of classes loaded in an embedded Java virtual machine without reducing its functionalities. We describe how to pack the constant pool by deleting entries which are only used during the class loading process. We present some benchmarks which demonstrate the efficiency of this mechanism. We finally suggest some additional optimizations which can be applied if some restrictions to the functionalities of the virtual machine can be tolerated.
Parallel Tempering with Equi-Energy Moves
Meili Baragatti,Agnès Grimaud,Denys Pommeret
Statistics , 2011,
Abstract: The Equi-Energy Sampler (EES) introduced by Kou et al [2006] is based on a population of chains which are updated by local moves and global moves, also called equi-energy jumps. The state space is partitioned into energy rings, and the current state of a chain can jump to a past state of an adjacent chain that has energy level close to its level. This algorithm has been developed to facilitate global moves between different chains, resulting in a good exploration of the state space by the target chain. This method seems to be more efficient than the classical Parallel Tempering (PT) algorithm. However it is difficult to use in combination with a Gibbs sampler and it necessitates increased storage. In this paper we propose an adaptation of this EES that combines PT with the principle of swapping between chains with same levels of energy. This adaptation, that we shall call Parallel Tempering with Equi-Energy Moves (PTEEM), keeps the original idea of the EES method while ensuring good theoretical properties, and practical implementation even if combined with a Gibbs sampler. Performances of the PTEEM algorithm are compared with those of the EES and of the standard PT algorithms in the context of mixture models, and in a problem of identification of gene regulatory binding motifs.
Likelihood-Free Parallel Tempering
Meili Baragatti,Agnès Grimaud,Denys Pommeret
Statistics , 2011,
Abstract: Approximate Bayesian Computational (ABC) methods (or likelihood-free methods) have appeared in the past fifteen years as useful methods to perform Bayesian analyses when the likelihood is analytically or computationally intractable. Several ABC methods have been proposed: Monte Carlo Markov Chains (MCMC) methods have been developped by Marjoramet al. (2003) and by Bortotet al. (2007) for instance, and sequential methods have been proposed among others by Sissonet al. (2007), Beaumont et al. (2009) and Del Moral et al. (2009). Until now, while ABC-MCMC methods remain the reference, sequential ABC methods have appeared to outperforms them (see for example McKinley et al. (2009) or Sisson et al. (2007)). In this paper a new algorithm combining population-based MCMC methods with ABC requirements is proposed, using an analogy with the Parallel Tempering algorithm (Geyer, 1991). Performances are compared with existing ABC algorithms on simulations and on a real example.
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