Genetic parameters of feeding behaviour and performance traits in group-housed Large White and French Landrace growing pigs

Data on feeding behaviour of 3 710 group-housed and ad libitum fed growing pigs were recorded using ’Acema 48’ electronic feed dispensers. Genetic parameters for six feeding behaviour criteria and the main production traits routinely recorded in French central test stations (three ’boar’ traits and three ’sib’ traits) were estimated in two breeds (Large White and French Landrace) using a multiple trait animal model DF-REML procedure. Heritability estimates for feeding behaviour criteria ranged from 0.36 to 0.54 and were markedly higher than that for the food conversion ratio (0.20). Heritability of daily feed intake was 0.42 in both breeds, whereas heritabilities of rate of feed intake, feed intake per meal and time per meal were slightly higher (0.45-0.54). Daily feed intake showed a very close genetic correlation (around 0.85) with average daily gain but also unfavourable genetic correlations with ultrasonic backfat thickness (around 0.5) and lean percentage (around -0.4). Daily feed intake was genetically independent of food conversion ratio, whereas average daily gain showed a favourable genetic correlation (around -0.35) with that trait. Among the feeding behaviour criteria, feed intake per meal and rate of feed intake showed the highest genetic correlations with daily feed intake (around 0.5) and average daily gain (around 0.4). They also showed moderately unfavourable genetic correlations with ultrasonic backfat thickness (around 0.25) and carcass lean percentage (around -0.25) and seemed to be genetically independent of food conversion ratio. The value of including a trait relating to feed intake pattern among traits selected for is discussed on the basis of this set of genetic parameters.Les données de comportement alimentaire de 3 710 porcs en croissance élevés en groupes et alimentés à volonté ont été récoltées à l’aide de distributeurs automatiques d’aliment «Acema 48». Les paramètres génétiques de six critères de comportement alimentaire et des principaux caractères de production mesurés en routine dans les stations publiques de contrôle des performances (trois caractères « candidats » et trois caractères « collatéraux») ont été estimés dans deux races (Large White et Landrace français) à l’aide de la méthode du maximum de vraisemblance restreinte (REML) appliquée à un modèle animal multicaractère. Les héritabilités des critères de comportement alimentaire sont comprises entre 0,36 et 0,54, et sont nettement supérieures à celle de l’indice de consommation (0,20). L’héritabilité de la consommation moyenne journalière est de 0,42 dans chacune des deux races tandis que celles de la vitesse d’ingestion, de la consommation moyenne par repas ou de la durée des repas sont légèrement plus élevées (0,45-0,54). La consommation moyenne journalière présente une corrélation génétique très élevée (de l’ordre de 0,85) avec le gain moyen quotidien mais aussi des corrélations génétiques défavorables avec l’épaisseur de lard dorsal (de l’ordre de 0,5) et le pourcentage de muscle (de l’ordre de - 0,4). La consommation moyenne journalière est génétiquement indépendante de l’indice de consommation tandis que le gain moyen quotidien présente une corrélation génétique favorable (de l’ordre de -0,35) avec ce caractère. Parmi les critères de comportement alimentaire, la consommation moyenne par repas et la vitesse d’ingestion sont les plus liées génétiquement à la consommation moyenne journalière (environ 0,5) et au gain moyen quotidien (environ 0,4). Ces critères présentent également des corrélations génétiques modérément défavorables avec l’épaisseur de lard dorsal (environ 0,25) et le pourcentage de muscle (environ -0,25) et semblent être génétiquement indépendants de l’indice de consommation. L’inclusion possible d’un critère de comportement alimentaire parmi les caractères sélectionnés est discutée sur la base de cet ensemble de paramètres génétiques

Mégalithes et météorisation des granites en Bretagne littorale, France du nord-ouest

Les menhirs sont des blocs granitiques de forme allongée qui ont été dressés à la verticale au cours du Néolithique. Ils sont particulièrement nombreux dans deux régions côtières de Bretagne, le Morbihan et le Trégor, et présentent à leur surface deux types de microformes : des vasques et des cannelures qui appartiennent elles-mêmes à deux générations. Certaines sont antérieures à la mise en place des menhirs (formes « prémégalithiques »), d'autres lui sont indiscutablement postérieures (formes « postmégalithiques »). Ainsi, de nombreuses vasques prémégalithiques, initialement formées sur des surfaces rocheuses proches de l'horizontale, s'observent aujourd'hui sur les parois verticales de certains menhirs, tandis que des vasques postmégalithiques, de moindres dimensions, ont été évidées à leur sommet. Les cannelures, quant à elles, ne se développent que sur les faces fortement redressées et ne se prolongent jamais en profondeur dans leur partie enterrée. Elles sont clairement le produit d'une météorisation postmégalithique et, comme les vasques, elles ont été façonnées par des processus subaériens. De telles microformes autorisent une approche de la vitesse de l'érosion puisque l'âge estimé des menhirs est de l'ordre de 5000 ans : si le creusement des cannelures a pu se faire au rythme de quelques dizaines de millimètres par millénaire, la mesure des vasques livre des chiffres plus variables, compris entre 4 et 30 mm/millénaire.Menhirs are elongate granite blocks placed upright, i.e. with the long axis in the vertical, in Neolithic times. Granite menhirs are prominent in the Morbihan and Trégor districts of coastal Brittany. Two minor forms, rock basins (also known as gnammas) and flutings (grooves, Rillen, Karren), are developed on menhirs. Two distinct generations of forms can be distinguished: those that predate the menhirs being placed upright, and those that postdate erection. Several flat-floored basins (or pans) that must have originated on flattish surfaces are now found on steeply inclined surfaces. On the other hand, smaller basins have developed on the summits of the monuments. Several flutings score the steep upper slopes of the blocks. They are deepest where they cut into outwardly convex inclined rock faces. They also diverge over such protuberances and terminate well above ground level. Clearly both the younger generation of basins and the flutings have formed after the monuments had been placed in their present upright positions and by processes active under subaerial or epigene conditions. In this last respect they stand in contrast with similar forms reported from other parts of the world. In Brittany the estimated age of menhirs is about 5000 years. Thus the flutings have deepened at a rate of a few tens mm/1000 years. The implied rate of basin development varies between 4 and 30 mm/1000 years

Inhomogeneous superconductivity induced in a weak ferromagnet

Under certain conditions, the order parameter induced by a superconductor (S) in a ferromagnet (F) can be inhomogeneous and oscillating, which results e.g. in the so-called pi-coupling in S/F/S junctions. In principle, the inhomogeneous state can be induced at T_c as function of the F-layer thickness d_F in S/F bilayers and multilayers, which should result in a dip-like characteristic of T_c(d_F). We show the results of measurements on the S/F system Nb/Cu_{1-x}Ni_x, for Ni-concentrations in the range x = 0.5-0.7, where such effects might be expected. We find that the critical thickness for the occurrence of superconductivity is still relatively high, even for these weak ferromagnets. The resulting dip then is intrinsically shallow and difficult to observe, which explains the lack of a clear signature in the T_c(d_F) data.Comment: 4 pages, 4 figures. To be publishedin Physica C (proceedings of the Second Euroconference on Vortex Matter in Superconductors, Crete, 2001

Droplet actuation induced by coalescence: experimental evidences and phenomenological modeling

This paper considers the interaction between two droplets placed on a substrate in immediate vicinity. We show here that when the two droplets are of different fluids and especially when one of the droplet is highly volatile, a wealth of fascinating phenomena can be observed. In particular, the interaction may result in the actuation of the droplet system, i.e. its displacement over a finite length. In order to control this displacement, we consider droplets confined on a hydrophilic stripe created by plasma-treating a PDMS substrate. This controlled actuation opens up unexplored opportunities in the field of microfluidics. In order to explain the observed actuation phenomenon, we propose a simple phenomenological model based on Newton's second law and a simple balance between the driving force arising from surface energy gradients and the viscous resistive force. This simple model is able to reproduce qualitatively and quantitatively the observed droplet dynamics

Local Density of States in Mesoscopic Samples from Scanning Gate Microscopy

We study the relationship between the local density of states (LDOS) and the conductance variation $\Delta G$ in scanning-gate-microscopy experiments on mesoscopic structures as a charged tip scans above the sample surface. We present an analytical model showing that in the linear-response regime the conductance shift $\Delta G$ is proportional to the Hilbert transform of the LDOS and hence a generalized Kramers-Kronig relation holds between LDOS and $\Delta G$. We analyze the physical conditions for the validity of this relationship both for one-dimensional and two-dimensional systems when several channels contribute to the transport. We focus on realistic Aharonov-Bohm rings including a random distribution of impurities and analyze the LDOS-$\Delta G$ correspondence by means of exact numerical simulations, when localized states or semi-classical orbits characterize the wavefunction of the system.Comment: 8 pages, 8 figure

Influence of fault geometries and mechanical anisotropies on the growth and inversion of hanging-wall synclinal basins: insights from sandbox models and natural examples

Salt is mechanically weaker than other sedimentary rocks in rift basins. It commonly acts as a strain localizer, and decouples supra- and sub-salt deformation. In the rift basins discussed in this paper, sub-salt faults commonly form wide and deep ramp synclines controlled by the thickness and strength of the overlying salt section, as well as by the shapes of the extensional faults, and the magnitudes and slip rates along the faults. Upon inversion of these rift basins, the inherited extensional architectures, and particularly the continuity of the salt section, significantly controls the later contractional deformation. This paper utilizes scaled sandbox models to analyse the interplay between sub-salt structures and supra-salt units during both extension and inversion. Series 1 experiments involved baseline models run using isotropic sand packs for simple and ramp-flat listric faults, as well as for simple planar and kinked planar faults. Series 2 experiments involved the same fault geometries but also included a pre-extension polymer layer to simulate salt in the stratigraphy. In these experiments, the polymer layer decoupled the extensional and contractional strains, and inhibited the upwards propagation of sub-polymer faults. In all Series 2 experiments, the extension produced a synclinal hanging-wall basin above the polymer layer as a result of polymer migration during the deformation. During inversion, the supra-polymer synclinal basin was uplifted, folded and detached above the polymer layer. Changes in thickness of the polymer layer during the inversion produced primary welds and these permitted the sub-polymer deformation to propagate upwards into the supra-salt layers. The experimental results are compared with examples from the Parentis Basin (Bay of Biscay), the Broad Fourteens Basin (southern North Sea), the Feda Graben (central North Sea) and the Cameros Basin (Iberian Range, Spain)