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Croissance néonatale et pédiatrique du chaton : description par race et facteurs de variation
Get PDFLa croissance est un paramètre capital du suivi de la santé d’un nouveau-né. L’objectif de ce travail était de décrire sur une grande population, la croissance du chaton de la naissance à l’âge de 2 mois et d’identifier les facteurs ayant une influence sur cette croissance. La taille de portée, la saison de mise-bas, la présence de mort-nés dans la portée et le sexe du chaton ont une influence statistique mais un effet biologique faible. A l’inverse, le groupe racial, le poids de naissance et le taux de croissance 0-2 jours montrent un effet biologique fort (h2 ~ 0,26). La cinétique de croissance étant dépendante du groupe racial, ce travail s’est également attaché à construire les courbes de croissance de référence pour 16 groupes de race fournissant ainsi aux éleveurs des outils de surveillance des chatons : tout décrochage doit motiver un examen clinique complet afin de décider d’une prise en charge adaptée
Study of the origin and impact of bias in national genetic and genomic evaluations : the case of dairy sheep.
Get PDFIn 2018 a new method called LR method was described to estimate bias in genetic evaluations. The method is based on comparing successive EBVs of a group of individuals, incrementing the information each time. It has estimators for bias, slope, and accuracies. The objective of this thesis were to evaluate bias in French dairy sheep evaluations, considering the effect of selection, using the LR method. Our first study was to check the capability of method LR to detect bias under simulated scenarios. We simulated a dairy species breeding scheme for low (0.10) and moderate (0.30) heritabilities. In both cases, we checked behavior of method LR for 3 scenarios: genetic evaluations (1) with a correct model, (2) when the evaluation model uses an incorrect heritability, and (3) when the data includes an environmental trend. For scenarios in which the evaluation model was correct, the LR method was capable of correctly estimating bias, slope, and accuracies. In cases of incorrect heritabilities in the evaluation model, the bias was correctly estimated in direction but not in magnitude. Similarly, the magnitudes of bias and slope were correctly estimated in scenarios with environmental trends in data, except for cases in which the model was unable to correctly estimate this environmental trend. In general, accuracies were well estimated in all scenarios. In this first study, we demonstrated that the LR method could estimate bias and accuracy in all cases if the evaluation model is correct or robust. The second study was to check the bias over real data. We used the genetic evaluation of milk yield in Manech Tête Rousse. We compared BLUP and single-step genomic BLUP (SSGBLUP) models. To account for missing pedigree, we used unknown parent groups (UPG), UPG with QP transformation in the H matrix (EUPG), and metafounders (MF) to manage the missing pedigree. We applied the LR method using the (G)EBVs of rams born in 2005 until 2014, with their (G)EBVs of the subsequent genetic evaluations. So, we obtained multiple estimators for the same model. We also compared across models: using EBVs of the first evaluation with BLUP and the subsequent GEBVs from SSGBLUP and comparing EBVs at birth with and without genomic information. Within models, in general, bias and overdispersion were small (bias: 0.20 to 0.40 genetic standard deviations; slope: 0.95 to 0.99). The estimates of accuracies confirmed that the addition of genomic information increases the accuracy of EBV in young rams. When we estimated dispersion by comparing a model with no markers to models with markers, SSGBLUPMF showed a value close to 1. In contrast, SSGBLUP-EUPG and SSGBLUP-UPG showed a significant underdispersion. Another important observation was the heterogeneous behavior of the estimates over time, which suggests that a single check could be insufficient to make a good analysis of genetic/genomic evaluations. In the third study, we analyzed the evolution of the genetic variance in Manech Tête Rousse for elite males and for all females (more representative of the population) born in each year from 1981 to 2014. We distinguished the loss of genetic variance due to drift (build-up of coancestry) and selection (mainly due to Bulmer effect). In both groups, the genetic variance decreased from the middle '90s until it reaches a stabilization around 2005. However, due to changes in the breeding objectives, it is impossible to conclude the real cause of the observed stabilization. The Bulmer effect impacted the loss of genetic variance of about 10%, while the build up of coancestry was about 3%
Catalysis of the electrochemical oxygen reduction reaction (ORR) by animal and human cells
Get PDFAnimal cells from the Vero lineage and MRC5 human cells were checked for their capacity to catalyse the electrochemical oxygen reduction reaction (ORR). The Vero cells needed 72 hours’ incubation to induce ORR catalysis. The cyclic voltammetry curves were clearly modified by the presence of the cells with a shift of ORR of 50 mV towards positive potentials and the appearance of a limiting current (59 μA.cm-2). The MRC5 cells induced considerable
ORR catalysis after only 4 h of incubation with a potential shift of 110 mV but with large experimental deviation. A longer incubation time, of 24 h, made the results more reproducible with a potential shift of 90 mV. The presence of carbon nanotubes on the electrode surface
or pre-treatment with foetal bovine serum or poly-D-lysine did not change the results.
These data are the first demonstrations of the capability of animal and human cells to catalyse electrochemical ORR. The discussion of the possible mechanisms suggests that these pioneering observations could pave the way for electrochemical biosensors able to characterize the protective system of cells against oxidative stress and its sensitivity to external agents
Thermal and dielectric fingerprints of self-assembling elastin peptides derived from exon30
Get PDFThree elastin peptides derived from a peculiar elastin sequence (exon 30) were investigated by Infra-red spectroscopy (IRTF), differential scanning calorimetry (DSC) and dielectric spectroscopy (DDS) to clarify the relationship between structural organization and physical properties of these peptides in the solid state. If a great majority of elastin derived peptides form organized structures, only few are able to coacervate, and only one, that is encoded by Exon 30, gives rise to an irreversible precipitation into amyloid fibers. The peptides studied in this work are constituted by 17, 18 or 22 amino acids whose sequences are contained in the longer exon 30. They all contain the XGGZG sequence (where X, Z = V, L) previously suspected to be responsible for amyloid formation in elastin peptides. Two of them gave rise to amyloid fibers while the other one was able to coacervate. In this work we attempted to correlate vibrational, thermal and dielectric behavior of these peptides in the solid state with the propensity to lead to reversible or irreversible aggregation in vivo
Assessment of interface failure behaviour for brittle adhesive using the three-point bending test
Get PDFIn the framework of the adhesive bonding, the assessment of interfacial properties has an essential role in determining the adhesive joints' global responses. Various surface preparations are available for each type of metallic substrate. There are plenty of tests widely used for mechanical characterisation to determine the adhesive properties and few tests to assess interfacial properties. For such a case, a specific three-point bending test can be applied to examine the interactions between adhesive and substrate. On the other hand, a direct comparison of the critical force is not always possible because of geometrical incompatibility. A practical solution for the last issue is applying a coupled stress-energy criterion (CC) since the interface properties are independent of the substrate thickness. Hence, CC and the macro-element technique were applied to determine the interfacial properties using an aluminium alloy 2024-T3 as substrate and the adhesive DGEBA/DETA™ under many preparation conditions. As a result, the three-point bending test's overall behaviour was established in terms of interface strength (adherence), including incremental energy release rate and critical stress. Thus, this paper can be read as the first work towards the ability to predict the interface failure in the frame of three-point bending test using different geometries. In conclusion, the occurrence of an adhesive or cohesive failure and the unstable or a stable failure propagation of the bonded joints were sorted and classified as a function of interface properties
Hypersaline microbial fuel cell equipped with an oxygen-reducing microbial cathode
Get PDFMicrobial anodes and oxygen reducing microbial cathodes were designed separately under constant polarization at +0.1 V/SCE in a hypersaline medium (NaCl 45 g/L). They were then associated to design two-compartment microbial fuel cells (MFCs). These MFCs produced up to 209 ±24 mW m-2 during a week. This was the first demonstration that hypersaline MFCs equipped with microbial cathodes can produce power density at this level. Desulfuromonas sp. were confirmed to be key species of the anodes. The efficiency of the cathodes was linked to the development of a redox system centred at +0.2 V/SCE and to the presence of Gammaproteobacteria (Alteromonadales and Oceanospirillales), especially an unclassified order phylogenetically linked to the genus Thioalobacter. Comparing the different performance of the four MFCs with the population analyses suggested that polarization at +0.1V/SCE should be maintained longer to promote the growth of Thioalobacter on the cathode and thus increase the MFC performance
A conservative multirate explicit time integration method for computation of compressible flows
Get PDFIn the context of high fidelity simulation of compressible flows (LES and DNS) at extreme scale (small time steps) on massively parallel supercomputers, explicit time integration methods are widely used since they both have a good computational cost trade-off at small time scales and require a small number of parallel communications, thus having little impact on the parallel strategy compared to their implicit counterpart.
However, the synchronous nature of the time integration of the governing equations can be a severe constraint when the stability condition is applied globally since the time scales are related to the flow properties and the mesh resolution, which may show strong variations throughout the computational domain. We propose to further improve the efficiency (CPU wall-time reduction) of explicit Runge-Kutta methods by developing a multirate explicit time integration method, by means of flux interpolation at the boundary between cells evolving with different time-steps, which enforces the conservation properties. In terms of computational efficiency, the presented multirate time integration method is easy to implement in pre-existing Eulerian compressible Navier-Stokes codes, requires less additional memory storage, and provides a considerable speed-up while being robust and preserving the order of accuracy of the legacy explicit Runge-Kutta time integration method. The multirate time integration method is implemented in the massively parallel finite volume and high-order (spectral difference) \IC3 code \cite{Bodart2016ECCOMAS} (fork of the solver \CharlesX), but it can also be applied to any flux-based spatial method such as discontinuous Galerkin or others. For a targeted on the developed turbulent channel flow test case at , a 2.48 effective speedup is obtained versus an expected theoretical speedup of 2.53
A well connected, locally-oriented and efficient multi-scale topology optimization (EMTO) strategy
Get PDFMulti-scale Topology Optimization (a.k.a. Micro-structural Topology Optimization, MTO) consists in optimizing macro-scale and micro-scale topology simultaneously. MTO could improve structural performance of products significantly. However a few issues related to connectivity between micro-structures and high computational cost have to be addressed, without resulting in loss of performance. In this paper, a new efficient multi-scale topology optimization framework (EMTO) has been developed for this purpose. Connectivity is addressed through adaptive transmission zones which limit loss of performance. A pre-computed database of micro-structures is used to speed up the computing. Design variables have also been chosen carefully and include the orientation of the micro-structures to enhance performance. The method has been successfully tested on two-dimensional compliance optimization problems. The results show significant improvements compared to mono-scale methods (compliance value lower by up to 20% on a simplistic case or 4% on a more realistic case), and also demonstrate the versatility of this method
Évaluation des attitudes de vétérinaires face à des demandes d'euthanasie non médicalement justifiées.
Get PDFL’euthanasie des animaux de compagnie est une pratique courante de la médecine vétérinaire. Cependant, les motifs invoqués par les propriétaires peuvent ne pas toujours être considérés comme justifiés par le vétérinaire. Afin de comprendre la position des vétérinaires français ainsi que leur attitude face à des demandes d’euthanasie non médicalement justifiée, ceux-ci ont été interrogés par le biais d’un questionnaire en ligne sur leur expérience, leur ressenti et leur réaction face à quatre situations différentes. Les résultats montrent qu’elles sont stressantes pour les vétérinaires, en partie à cause de l’absence de bonnes pratiques prédéfinies par la profession, mais également du manque de solutions alternatives à proposer. La majorité des vétérinaires tentent du mieux possible de se baser sur le bien-être animal lors de la prise de décision, alors que d’autres semblent privilégier celui du propriétaire
Hydrodynamic torque on a slender cylinder rotating perpendicularly to its symmetry axis
Get PDFUsing fully-resolved simulations, we examine the torque experienced by a finite-length circular cylinder rotating steadily perpendicularly to its symmetry axis. The aspect ratio χ, i.e., the ratio of the length of the cylinder to its diameter, is varied from 1 to 15. In the creeping-flow regime, we employ the slender-body theory to derive the expression of the torque up to order 4 with respect to the small parameter 1/ ln(2χ). Numerical results agree
well with the corresponding predictions for χ = 3. We introduce an ad hoc modification in the theoretical prediction to fit the numerical results obtained with shorter cylinders, and a second modification to account for the increase of the torque resulting from finite inertial effects. In strongly inertial regimes, a prominent wake pattern made of two pairs of counter-rotating vortices takes place. Nevertheless the flow remains stationary and exhibits
two distinct symmetries, one of which implies that the contributions to the torque arising from the two cylinder ends are identical. We build separate empirical formulas for the contributions of pressure and viscous stress to the torque provided by the lateral surface and the cylinder ends.We show that, in each contribution, the dominant scaling law may be inferred from simple physical arguments. This approach eventually results in an empirical formula for the rotation-induced torque valid throughout the range of inertial regimes and aspect ratios considered in the simulations