431 research outputs found
The growth and feeding of the Bulwer's Petrel (Bulweria bulwerii) chicks on Selvagem Grande (30Âş09'N, 15Âş52'W)
La croissance pondérale et staturale des poussins de Pétrels de Bulwer, Bulweria bulwerii, de Selvagem Grande (30º09’N, 15°52’W) ne diffère en rien de ce qui est habituel chez les Procellariidés. A partir d’un poids à la naissance un peu inférieur au poids de l’oeuf. Une croissance rapide puis ralentie amène les poussins à un poids maximum supérieur au poids de l’adulte. Par la suite, le poids corporel s’abaisse et, à l’envol, ii est un peu inférieur à celui des adultes. La croissance de l’aile, lente avant la pousse des rémiges, puis rapide. Ne s’achève qu’au moment de l’envol. La croissance du culmen et celle du tarse, d’abord rapides puis ralenties s’achèvent respectivement aux environs des deux-tiers et de la moitié du séjour au nid des poussins. La fréquence des repas est à peu près constante pendant toute la période d’accroissement pondéral. Il est probable qu’elle diminue par la suite. Le poids du repas augmente rapidement pendant la première décade de la vie, puis diminue très lentement. Dans ces conditions, la quantité de nourriture consommée quotidiennement augmente pendant la première décade, reste à peu près constante pendant les trois suivantes, puis décroit. Au total, un poussin aura consommé au cours de sa croissance un peu plus de 0,5 kg de nourriture, dont une partie sous forme d’huile stomacale, ce qui semble correspondre à un prélèvement en mer de 1,5 kg, soit environ 17% de la consommation familiale pendant la même période.ABSTRACT: The growth of the chicks of the Bulwer’s Petrel, Bulweria bulwerii, on Selvagem Grande (30º09’N, 15°52’W) shows no differences with what is usual among Procellariidae. The weight at birth is slightly lower than that of the egg. The subsequent increase, rapid at the beginning, slows down, and a maximum weight higher than the adult weight is reached. Later on the body weight lowers and, at fledging, is slightly lower than that of the adult. The wing grows slowly before the appearance of the remiges, then rapidly, and stops at fledging. The growth of the culmen and tarsus, rapid at first, slows down and stops respectively at the two thirds and at half of the chick sojourn on the nest. The feeding frequency, is almost constant during the period of weight gain, and probably lessens afterwards. In these conditions the amount of food eaten daily increases during the first decade of life, remains constant during the following three, and lessens afterwords. On the whole, a chick eats during its growth a little more than 0.5 kg of food, part of which as stomach oil, which seems to correspond to a catch of 1.5 kg, or about 17% of the family intake during the same period
Universal pinning energy barrier for driven domain walls in thin ferromagnetic films
We report a comparative study of magnetic field driven domain wall motion in
thin films made of different magnetic materials for a wide range of field and
temperature. The full thermally activated creep motion, observed below the
depinning threshold, is shown to be described by a unique universal energy
barrier function. Our findings should be relevant for other systems whose
dynamics can be modeled by elastic interfaces moving on disordered energy
landscapes.Comment: 10 pages, 3 figure
Mystérieuses filiations : Husserl et Heidegger, Freud et Jung
International audienceThis text presents in a phenomenological way what generates the reading of two great figures of the thought of the XXth century (Husserl and Freud) as well as the reading of their principal students (Heidegger and Jung). This text analyzes the specificities of "fathers" and those of spiritual "sons" in the tradition of phenomenology and psychoanalysis with regard to their cultural and religious family tradition.Ce texte présente de manière phénoménologique ce que génère la lecture de deux grands figures de la pensée du XXème siècle (Husserl et Freud) ainsi que la lecture de leurs principaux élèves (Heidegger et Jung). Ce texte analyse les spécificités de "pères" et celles des "fils" spirituels dans la tradition de la phénoménologie et de la psychanalyse au regard de leur tradition familiale culturelle et religieuse
Démographie du Puffin cendré Calonectris diomedea de Selvagem Grande (30° 09' n, 15° 52' w)
The breeding numbers of the Cory ' s Shearwaters Calonectris diomedea of Selvagem
Grande (30° 09' N, 15 ° 52' W) have shown important variations during the last three decades,
decreasing from about 100,000 birds at the beginning of the seventies to 5,000 only in 1 977
following depredations, and increasing regularly since then to reach nowadays about 30,000.
The mean age at first breeding is 8.9 years. Every year, 11.8 % of the breeders temporarily
stop breeding, these sabbatical leaves lasting 1.7 years on average and 7 years at most. 56.6 %
of the eggs laid produce fledglings, with significant variations between years. The mean
annual survival rate of the adults is comparatively low, 92.7 %, higher for females (93.5 %)
than for males (91.9 %) and varying significantly between years (min. : 84.1 %, max.:
98.0 % ). The survival rate of the immatures between fledging and first breeding is 32.8 % at
!east. Selvagem Grande population, which numbered an important proportion of young
inexperienced birds at the beginning of the eighties, following the depredations of the
seventies, has gained age and experience during the eighties and the nineties. But the
relatively low annual survival rate of the adults, which is probably linked to the development
of new fishing methods, is an alarming sign for the future of the population of Cory' s
Shearwaters, notwithstanding the conservation actions engaged in the breeding localitiesLes effectifs des Puffins cendrés Calonectris diomedea de Selvagem Grande (30° 09' N, 15° 52' W) ont montré au cours des trois dernières décennies des variations considérables, passant de 100 000 reproducteurs environ au début des
années 70 à 5 000 seulement en 1977 à la suite de déprédations, et augmentant régulièrement depuis lors pour atteindre aujourd'hui environ 30 000. La reproduction s'établit en moyenne à 8,9 années. Chaque année, 11,8 % des reproducteurs ne nichent pas, les interruptions temporaires de la
reproduction durant en moyenne 1,7 années et au maximum 7 ans. 56,6 % des oeufs pondus produisent des poussins en fin de croissance, des variations significatives existant d'une année à l'autre. Le taux de survie annuel des adultes est relativement faible, 92,7 %. Il est plus élevé chez les
femelles (93,5 %) que chez les mâles (91,9 %) et il varie significativement d'une année à l'autre (min.: 84,1 %, max. : 98,0 %). Enfin, le taux de survie des immatures entre l'envol en fin de croissance et la première reproduction est au moins égal à 32,8 %. La population de Selvagem Grande,
qui comptait une proportion importante de jeunes oiseaux inexpérimentés au début des années 80, à la suite des massacres de reproducteurs de la fin-des années 70, a acquis de l'âge et de l'expérience au cours des décennies 80 et 90. Mais la relative faiblesse du taux de survie annuel des
adultes, qu'il faut sans doute mettre en relation avec le développement de nouvelles méthodes de pêche, est un signe inquiétant pour l'avenir des populations de Puffins cendrés, malgré les mesures de protection prises sur les lieux de reproduction
A phenomenological approach to investigate the pre-reflexive contents of consciousness during sound production
International audienceThis article describes a listening experiment based on elici-tation interviews that aims at describing the conscious experience of a subject submitted to a perceptual stimulation. As opposed to traditional listening experiments in which subjects are generally influenced by closed or suggestive questions and limited to predefined, forced choices, elicita-tion interviews make it possible to get deeper insight into the listener's perception, in particular to the pre-reflexive content of the conscious experiences. Inspired by previous elicitation interviews during which subjects passively listened to sounds, this experience is based on an active task during which the subjects were asked to reproduce a sound with a stylus on a graphic tablet that controlled a synthesis model. The reproduction was followed by an elicitation interview. The trace of the graphic gesture as well as the answers recorded during the interview were then analyzed. Results revealed that the subjects varied their focus towards both the evoked sound source, and intrinsic sound properties and also described their sensations induced by the experience
El tratamiento con 5azadC regula al alza el nivel de miR-375 y reprime la expresiĂłn de HPV16 E6
High-risk human papillomaviruses are the etiological agents of cervical cancer and HPV16 is the most oncogenic genotype. Immortalization and transformation of infected cells requires the overexpression of the two viral oncoproteins E6 and E7 following HPV DNA integration into the host cell genome. Integration often leads to the loss of the E2 open reading frame and the corresponding protein can no longer act as a transcriptional repressor on p97 promoter. Recently, it has been proposed that long control region methylation also contributes to the regulation of E6/E7 expression. To determine which epigenetic mechanism is involved in HPV16 early gene regulation, 5-aza-2?-deoxycytidine was used to demethylate Ca Ski and SiHa cell DNA. Decreased expression of E6 mRNA and protein levels was observed in both cell lines in an E2-independent manner. E6 repression was accompanied by neither a modification of the main cellular transcription factor expression involved in long control region regulation, nor by a modification of the E6 mRNA splicing pattern. In contrast, a pronounced upregulation of miR-375, known to destabilize HPV16 early viral mRNA, was observed. Finally, the use of miR-375 inhibitor definitively proved the involvement of miR-375 in E6 repression. These results highlight that cellular DNA methylation modulates HPV16 early gene expression and support a role for epigenetic events in high-risk HPV associated-carcinogenesis
Three-dimensional use of marine habitats by juvenile emperor penguins Aptenodytes forsteri
International audienceThe juvenile phase is poorly known in Antarctic seabirds, despite being a critical period for individual survival. To better understand the ecology of young Antarctic seabirds, we surveyed for the first time the three-dimensional habitat use of six juvenile emperor penguins during their post-natal dispersal from Terre Ade'lie, using bio-telemetric tags. The tags transmitted location and activity data for nearly 100 days on average. One individual was followed during eight months and covered 7000 km, which represents the longest continuous individual survey for the species. Studied individuals first dispersed away from Antarctica, up to 54.78S and 1250 km north of the pack-ice edge, in the Polar Frontal Zone. This highlighted a much looser association with sea ice and a greater at-sea range compared to previous knowledge on breeding adults. Juvenile penguins then moved southwards close to the extending pack-ice during autumn and winter. Over the survey duration, juveniles showed a contrasting use of marine habitats, with less mobility, less time underwater, and shallower dives (generally not over 50-100 m) in the pack ice, versus greater distances travelled, more time spent underwater, especially deeper than 100m (up to 250-300 m) in open water. We discuss hypotheses which could explain the northward exodus of juvenile emperor penguins across contrasting habitats
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