Présence avifaunistique, traits biologiques, milieu écologique : relations causales en montagne

The higher the elevation in mountain environment, the lower the number of bird species. This is generally attributed to a progressive simplification from a wooded to a grassed then a mineral environment. This approach calls more on the notion of "landscape" than on that of "resources". For all that, nest building birds must present biological traits (body size, feeding, breeding and migratory behaviours) that are consistent with the possibilities offered (seasonal temperatures, feeding and nesting sites). An ornithological transect conducted in Vanoise attempts to take these diverse factors into consideration. Five nutritional types are recognized, from exclusive insectivores to omnivores / carnivores. A crucial parameter is size (= individual biomass) which determines migratory behaviour via the heat-energy balance. The larger species are in principle more suitable for inhabiting the highest reaches, and their systematically lower number can explain the elevation-related reduction in birdlife richness. In fact, rather than talk of “causes” and "consequences", a systemic approach would appear to be necessary where each phenomenon is viewed both as a cause and an effect in a system where environmental characters and biological traits must present reciprocal consistencies. And that in different wooded and alpine tiers, with the latter being more simple and more constraining than the formerLa richesse de l'avifaune paraît liée à la diversité du paysage, végétal et minéral; en montagne, on observe une diminution altitudinale du nombre des espèces d'oiseaux, attribuée à la simplification progressive des milieux, boisés à herbacé puis minéral. Mais cette approche fait davantage appela la notion de « paysage » qu'à celle de « ressources ». Pour autant, l'avifaune nichant dans de tels milieux doit présenter des traits biologiques cohérents avec les possibilités offertes (température saisonnière, sites de nourriture et de nidification). Cinq types nutritionnels sont ici reconnus, d'insectivore intégral à omnivore / carnivore. Un paramètre déterminant est constitué par la taille (= biomasse individuelle), qui met en cause l'équilibre thermo-énergétique et le comportement migratoire. Les plus grosses espèces sont a priori favorisées pour peupler les plus hauts niveaux, et leur nombre systématiquement réduit peut justifier la baisse altitudinale de la richesse avienne. En fait, plus que de parler de « causes » et de « conséquences », une approche systémique paraît nécessaire, où chaque phénomène doit être vu à la fois comme cause et comme effet, dans un schéma où caractères de milieu et traits biologiques doivent présenter des cohérences réciproques. C'est en cela que diffèrent profondément étages boisés et alpin, le second plus simple et plus contraignant que les premiers

Increasing Needs and Solutions for Non-Baseload Operation of Nuclear Power Plants

Operation at steady full power, i.e. baseload operation, of nuclear power plants (NPPs) is usually considered to be the most efficient use of capital investment. Therefore, design and operation of most existing nuclear power plants (NPPs) are optimised to operate in baseload mode. Recently, there is an increasing need to operate NPPs in non-baseload mode, specifically performing frequency control and load following. These needs are typically due to a large nuclear generating capacity, increasing share of renewable generation, deregulation or evolution of the electricity supply systems and markets. Re-optimization of NPP design and operation for nonbaseload (flexible) mode of operation necessitates operational, economic and financial rearrangements to maintain the capital investment, in addition the adaptation of technical and regulatory changes. This paper discusses the aspects of design or operation of NPPs in flexible mode based on the existing knowledge and experience and it is primarily based on the recent study that was prepared by the International Atomic Energy Agency (IAEA)

Comparison of Medio-european and Mediterranean fir and pine forest bird communities

Bird communities of 11 fir forests (Abies pectinata and A. pinsapo + maroccana) and 6 pine forests (Pinus silvestris and P. pinaster) were compared along a 2000 km transect from the Vosges (N.-E. France) to the Middle Atlas (Marocco). A common background of ca 15 Palearctic bird species accounts for three quarters of relative abundances in all communities. However, significant differences appear at several levels. (1) Between the medio-european and Mediterranean biogeographical areas, middle latitudes of Spain prevent the presence southward of ca 10 species, such as the Goldcrest and the Bullfinch. Conversely, although belonging to the same faunistic region, 11 species, such as the Short-toed Tree Creeper and the Serin, are more frequent in the Mediterranean than further north. Over the two forest types investigated, there are only 33 Passerine species, over a total of 54, common to Middle Europe and the Mediterranean area. (2) Abies and Pinus forests have in common a striking figure of 46 bird species. The distinctive species are the Firecrest and the Blackcap in fir forests, the Crested Tit and the Common Crossbill in pine forests. As already noted by various authors, as a consequence of its insularity and mesological peculiarities the Mediterranean forest avifauna can be considered as an impoverished version of its Medio-european counterpart. (3) At the broad regional scale, a multivariate analysis shows an avifaunistic gradient running from climacic forests, mainly on north-facing slopes from Vanoise (French Alps) to the Pyrenees, to para-climacic pre-forests, mainly on south-facing slopes, in Andalucia and Marocco. In the former case, boreal bird species account for three quarters of the abundances in the community but less than half in the latter where the rest consists predominantly of rather biogeographically and ecologically ubiquitous species (Carduelinae, Woodlark, Rock Bunting) which, for a mix of ecological and anthropogenic reasons, are able to colonize more and more common southward thermo-xerophilous and open wooded landscapesLa comparaison de l'avifaune de 11 sapinières (Abies pectinata et Abies pinsapo / maroc-cana) et de 6 pinèdes (Pinus silvestris et Pinus pinaster), échelonnées des Vosges au Moyen-Atlas sur un transect de 2000 km, montre l'existence d'un fond commun constitué par une quinzaine d'espèces d'oiseaux paléarctiques représentant les trois quarts du peuplement global (en abondance relative). Des différences significatives apparaissent néanmoins à plusieurs niveaux. (1) Entre les deux situations biogéographiques médio-européenne et méditerranéenne, l'Espagne moyenne joue le rôle d'obstacle vers le sud pour une dizaine d'oiseaux, du Roitelet huppé au Bouvreuil ; inversement, tout en relevant du même domaine faunistique, 11 espèces sont plus fréquentes en Méditerranée, du Grimpereau des jardins au Serin cini. Essences forestières confondues, il n'y a que 33 espèces en commun chez les 54 Passereaux inventoriés. (2) Entre les peuplements à Abies et Pinus, il n'y a pas moins de 46 espèces communes aux deux types de formations, indépendamment de leur localisation biogéographique ; les oiseaux discriminants sont le Roitelet triple-bandeau et la Fauvette à tête noire dans les sapinières, la Mésange huppée et le Beccroisé des sapins dans les pinèdes. Comme déjà noté par divers auteurs, l'avifaune sylvicole méditerranéenne peut être considérée comme un reflet appauvri de son homologue médio-européenne, phénomène dû à son insularité et à ses particularités mésologiques. (3) À l'échelle générale, une analyse multivariée fait apparaître un gradient au long duquel le passage se fait depuis les formations et avifaunes climaciques à dominante d'ubac, présentes de la Vanoise aux Pyrénées, jusqu'aux formations et avifaunes pré-forestières paraclimaciques à dominante d'adret, en Andalousie et au Maroc. Dans le premier cas, l'avifaune boréale représente les trois quarts de l'abondance du peuplement avien, contre moins de la moitié dans le second. Plus qu'à une avifaune vraiment méditerranéenne, le complément fait appel à des espèces biogéographiquement et écologiquement plutôt ubiquistes (Carduélinés, Alouette lulu, Bruant fou), susceptibles de coloniser les boisements thermo-xérophiles et ouverts de plus en plus présents vers le sud, pour des raisons aussi bien naturelles qu'anthropiques

Une approche synécologique des milieux humides savoyards et de leur avifaune

Une étude a été conduite de la répartition qualitative de 78 espèces d’oiseaux dans 25 milieux humides de Savoie, déterminés par leur structure végétale. Cette matrice de données a été analysée par la technique des coefficients d’affinité (Jaccard, Czekanovski ) et celle, plus moderne, de l’analyse factorielle des correspondances. Les milieux jugés à travers leur avifaune s’ordonnent selon un axe paludicole principal, sur lequel se greffent deux axes latéraux d’eau libre, courante et stagnante. Correspondant à la notion de série de végétation et déterminée par elle, se dégage la notion de séquence ornithologique. Diverses relations ont été établies concernant le nombre d’espèces aviennes en relation avec le nombre de strates végétales, ainsi que la répartition de l’avifaune en espèces migratrices et/ou plus généraux de structure des peuplements aviens en relation carnivores. Le présent travail est donc un apport aux problème-, plus généraux de structure des peuplements aviens en relation avec leur milieu.A study was carried out in Savoie, France, on the distribution of 78 bird species in 25 wetland areas having different structural characteristics. The matrix of data so obtained has been analy sed in two main ways : by using the affinity coefficient of Jaccard and Czekanovski and the more modern method of correspon dance factor analysis. Differences in distribut;on of birds in marshes with running or stagnant water have been recognized, and the concept of “ ornithological sequence ” can be related to the concept of “ seres of vegetation ", which seems largely to determine the distribution pattern of the bird species. Rela tionships have been established between the number of bird species and the number of vegetation strata, as well as details about the particular distribution of migratory and/or carnivorous species

An independent determination of Fomalhaut b's orbit and the dynamical effects on the outer dust belt

The nearby star Fomalhaut harbours a cold, moderately eccentric dust belt with a sharp inner edge near 133 au. A low-mass, common proper motion companion (Fom b), was discovered near the inner edge and was identified as a planet candidate that could account for the belt morphology. However, the most recent orbit determination based on four epochs of astrometry over eight years reveals a highly eccentric orbit that appears to cross the belt in the sky plane projection. We perform here a full orbital determination based on the available astrometric data to independently validate the orbit estimates previously presented. Adopting our values for the orbital elements and their associated uncertainties, we then study the dynamical interaction between the planet and the dust ring, to check whether the proposed disk sculpting scenario by Fom b is plausible. We used a dedicated MCMC code to derive the statistical distributions of the orbital elements of Fom b. Then we used symplectic N-body integration to investigate the dynamics of the dust belt, as perturbed by a single planet. Different attempts were made assuming different masses for Fom b. We also performed a semi-analytical study to explain our results. Our results are in good agreement with others regarding the orbit of Fom b. We find that the orbit is highly eccentric, is close to apsidally aligned with the belt, and has a moderate mutual inclination relative to the belt plane of. If coplanar, this orbit crosses the disk. Our dynamical study then reveals that the observed planet could sculpt a transient belt configuration with a similar eccentricity to what is observed, but it would not be simultaneously apsidally aligned with the planet. This transient configuration only occurs a short time after the planet is placed on such an orbit (assuming an initially circular disk), a time that is inversely proportional to the planet's mass, and that is in any case much less than the 440 Myr age of the star. We constrain how long the observed dust belt could have survived with Fom b on its current orbit, as a function of its possible mass. This analysis leads us to conclude that Fom b is likely to have low mass, that it is unlikely to be responsible for the sculpting of the belt, and that it supports the hypothesis of a more massive, less eccentric planet companion Fom c.Comment: 17 pages, 15 figures, accepted for publication in Astronomy \& Astrophysic

0304: How long should we keep a temporary pace maker after transcatheter aortic valve replacement (TAVR)

A temporary pace-maker (TPM) is often used after TAVR due to the risk of atrioventricular block (AVB) in the following days, related to progressive conduction system injuries. However guidelines are unclear as when to safely remove it. Between 2013 and 2014, 195 patients without previous permanent pacemaker, were prospectively followed after TAVR (69 Edwards Sapiens (ES) and 126 CoreValve (CV)). 47 had preoperative bundle branch block, 23 left (LBBB), 24 right sided (RBBB). Peri-operative high degree AVB was noted in 37 patients (20%). 24 were transient, less than 10mn and; 13 persisted at the end of the procedure and were implanted with a permanent pace-maker. New LBBB was observed in 55 patients (28%). In the post-operative period, 23 patients (13%) developped AVB (20 patients within 5 days, and 3 patients after 7 days) (4 ES and 19 CV). No new AV block had occurred at one month in the remaining population. Risk factors for late AVB were peri-operative transient AVB (40%), post-operative RBBB (30%), or LBBB (20%); preexistent RBBB and Corevalve model. Conversely 41 of the 42 patients without AVB or bundle branch block did not need temporary pacing in the post operative time. The only patient without any perioperative event who developed a late AV block at day 7 had a CV inserted in an old surgical valve. However, sinus dysfunction occurred in 2 patients treated with amiodarone for atrial fibrillation in the post operative period, needing temporary pacing. Conclusion: The use of TPM after TAVR is common for the management of delayed high degree AVB. The main risk factors are peri-operative AVB and post-operative BBB. Most of delayed AVB occur within 5 days. Later AVB preceded by prolonged PR interval and BBB should increase the length of TPM. However, in the absence of these factors TPM could be shortened.Abstract 0304 – Figure: Time occurence of AVB (CV=Corevalve, ES=Sapien

Exozodiacal clouds: hot and warm dust around main sequence stars

peer reviewedA warm/hot dust component (at temperature $>$ 300K) has been detected around $\sim$ 20% of stars. This component is called "exozodiacal dust" as it presents similarities with the zodiacal dust detected in our Solar System, even though its physical properties and spatial distribution can be significantly different. Understanding the origin and evolution of this dust is of crucial importance, not only because its presence could hamper future detections of Earth-like planets in their habitable zones, but also because it can provide invaluable information about the inner regions of planetary systems. In this review, we present a detailed overview of the observational techniques used in the detection and characterisation of exozodiacal dust clouds ("exozodis") and the results they have yielded so far, in particular regarding the incidence rate of exozodis as a function of crucial parameters such as stellar type and age, or the presence of an outer cold debris disc. We also present the important constraints that have been obtained, on dust size distribution and spatial location, by using state-of-the-art radiation transfer models on some of these systems. Finally, we investigate the crucial issue of how to explain the presence of exozodiacal dust around so many stars (regardless of their ages) despite the fact that such dust so close to its host star should disappear rapidly due to the coupled effect of collisions and stellar radiation pressure. Several potential mechanisms have been proposed to solve this paradox and are reviewed in detail in this paper. The review finishes by presenting the future of this growing field