69 research outputs found
Influence de la pluviométrie et de la mise en place du barrage de Petit Saut (Guyane française) sur la répartition des lépidoptÚres Sphingidae
The family Sphingidae bas an important potential as bio-indicators given the 118 species
so far enumerated in French Guiana. For instance, more than 25,000 individuals from
104 species have been captured during 90 monthly censuses between January 1990 and
October 1997 in the region of Petit Saut, a low-altitude primary forest. Among these species,
seven are considered as uncommon on the site of Petit Saut. Therefore, ca 50 % of the species
with a sufficient number of individuals for the analysis (n = 30) display particular characteristics:
the probability of occurrence differs significantly between months for 14.5 % of them,
and for the majority of the species of this farnily seasonal variations in populations
abundances are not linked to rainfall, which is usually the most important ecological factor
in this environment, temperature being constant in Guianan forest. These fluctuations are
therefore due to other factors. The filling of the dam reservoir affected about a third of the
species. Adaptations to variations in environmental conditions are not identical across all
species . Certain species were not affected by environmental modifications while others grew
up taking advantage of these changes and colonized new biotopes, and others decreased.La famille des Sphingidés a des capacités bio-indicatrices trÚs performantes compte tenu
des 118 espÚces connues en Guyane française. Par exemple, plus de 25 000 individus
appartenant à 104 espÚces ont été capturés lors des 90 piégeages mensuels effectués entre
janvier 1990 et octobre 1997 dans une zone de forĂȘt primaire de basse altitude dans la rĂ©gion
de Petit Saut. Parmi ces espĂšces, sept peuvent ĂȘtre considĂ©rĂ©es comme rares sur le site du
barrage de Petit Saut. Par ailleurs, prÚs de la moitié des espÚces ayant un nombre suffisant
d'individus pour les analyses (n = 30), présentent un comportement particulier : 14,5 % ont
une probabilité d'apparition différente d'un mois à l'autre et pour la plupart des espÚces de
cette famille, les variations saisonniÚres observées dans les effectifs ne sont pas liées à la
pluviométrie qui est le facteur prépondérant de cet environnement, la température restant
constante tout au long de l'annĂ©e en forĂȘt guyanaise. D'autres facteurs sont Ă l'origine de cette
fluctuation. On peut observer que, selon les espĂšces, les adaptations aux variations des
conditions environnementales ne sont pas identiques. En effet, de nombreuses espĂšces ne sont
pas influencées par ces modifications du milieu tandis que prÚs d'un tiers des espÚces sont
affectées dans leur apparition par la mise en eau du barrage de Petit Saut. Certaines espÚces
se sont développées en mettant à profit ces changements et en colonisant de nouveaux
biotopes, d'autres voyant leurs effectifs diminue
Influence of the setting up of a man-made lake on mercury levels in the flesh of fish in a neotropical habitat: the Sinnamary river (french Guiana)
The filling of the hydroelectric dam reservoir at Petit Saut (French Guiana) in January
1994 brought about changes in the water quality in the reservoir and downstream. The thermal
stratification of the waters of the reservoir has resulted in the rapid establishment of an
oxygenated epilimnion and an anoxie hypolimnion. Moreover, since 1870, activities linked to
gold mining are responsible for the rejection of metallic mercury into the Guianese
environment where it accumulates in the food chain. In order to study the consequences of the
filling of the dam reservoir at Petit Saut, the total level of mercury in the flesh of the fish in
the catchment basin of the Sinnamary River was analyzed on 1,690 fish specimens sampled between 1993 and 1998. This study showed that mercury concentrations increase progressive1y
over time, with most of the changes since the filling of the reservoir occurring
downstream. The evacuation of the hypolimnic waters seems to influence what becomes of
the metal in the food chain. Mercury concentrations in the herbivorous fish did not evolve
over time, and remained very 1ow. Among the omnivorous and carnivorous species, an
increase in the concentrations was essentially observed in fish samp1ed downstream. Three
fish species representing herbivorous (Myleus ternetzi), omnivorous (Leporinus friderici), and
carnivorous (Hoplias aimara) species were studied in particu1ar. No significant increase was
visible in the reservoir itself, but one cou1d observe the progressive homogenization of the
mass of water that triggers, through the trophic chain, the polluting of fish in the epilimnic
zoneLa mise en eau du barrage hydroélectrique de Petit Saut en Guyane française en janvier
1994 a entraßné des modifications de la qualité de l'eau au sein du réservoir et dans la partie
aval. La stratification thermique des eaux de la retenue a pour conséquence la mise en place
rapide d'un épilimnion oxygéné et d'un hypolimnion anoxique. Par ailleurs, depuis 1870, les
activités miniÚres liées à l'or sont responsables de rejets de mercure métallique dans le milieu
guyanais oĂč il s'accumule dans la chaĂźne alimentaire. Afin d'Ă©tudier les consĂ©quences de la
mise en eau du barrage de Petit Saut, le mercure total a été analysé dans la chair des poissons
du bassin versant du fleuve Sinnamary. L'étude de 1690 individus prélevés entre 1993 et 1998
montre que les concentrations en mercure augmentent progressivement au fil du temps,
l'essentiel des modifications se situant dans la zone aval de la retenue depuis la mise en eau.
L'évacuation d'eaux hypolimniques semble influencer le devenir du métal dans la chaßne
alimentaire. Les herbivores ne présentent pas d'évolution au fil du temps, les concentrations
restant trĂšs faibles. Chez les omnivores et les carnivores, l'augmentation des concentrations
est observée essentiellement au niveau du tronçon aval. Trois espÚces représentatives du
groupe des herbivores (Myleus ternetzi), des omnivores (Leporinus friderici) et des carnivores
(Hoplias aimara) ont été étudiées plus particuliÚrement. Au niveau de la retenue, aucune
augmentation significative n'est visible, mais on pourrait assister à une homogénéisation
progressive de la masse d'eau, entraĂźnant, au travers des chaĂźnes trophiques, une pollution des
poissons de la zone Ă©pilirnniqu
Allogenic hematopoietic stem cell transplantation after reduced intensity conditioning regimen for elderly patients (60 years and older) with hematologic malignancies using unrelated donors: a retrospective study for the French society for stem cell transplantation (SFGM-TC)
Peer reviewe
CURSO DIĂRIO E SAZONAL DO POTENCIAL HĂDRICO FOLIAR DE MOGNO EM SISTEMAAGROFLORESTAL1
Este trabalho objetivou avaliar o curso diĂĄrio e sazonal do potencial hĂdrico foliar de mogno (Swietenia macrophylla King) (Meliaceae) em sistema agroflorestal (SAF). O experimento foi realizado em ĂĄrvores de S. macrophylla plantadas num sistema agroflorestal instalado no Campo Experimental da Embrapa AmazĂŽnia Ocidental, Manaus, AM. Avaliou-se o potencial hĂdrico foliar (Κf) dos cursos diĂĄrio e sazonal nos anos 2004 e 2005, por meio da utilização de bomba de pressĂŁo tipo Scholander. Os resultados indicaram que os valores do Κf de S. macrophylla, de modo geral, foram superiores no inĂcio da manhĂŁ e no final da tarde, com redução acentuada ao meio-dia, e que, em relação Ă sazonalidade de precipitação, as menores taxas foram reportadas para a Ă©poca menos chuvosa, variando de -26 bar em 2004 para -31bar em 2005. Verificou-se que o potencial hĂdrico de Swietenia macrophylla em sistema agroflorestal sofreu reduçÔes significativas em razĂŁo dos baixos Ăndices pluviomĂ©tricos entre junho e outubro de 2005
La connaisance sur les milieux aquatiques : zone estuarienne et bande littorale en Guyane, une biodiversité méconnue, une zone essentielle
Présentation de l\u27exceptionnelle biodiversité de l\u27espace guyanais
Interspecific variation of warning calls in piranhas: a comparative analysis
Fish sounds are known to be species-specific, possessing unique temporal and spectral features. We have recorded and compared sounds in eight piranha species to evaluate the potential role of acoustic communication as a driving force in clade diversification. All piranha species showed the same kind of sound-producing mechanism: sonic muscles originate on vertebrae and attach to a tendon surrounding the bladder ventrally. Contractions of the sound-producing muscles force swimbladder vibration and dictate the fundamental frequency. It results the calling features of the eight piranha species logically share many common characteristics. In all the species, the calls are harmonic sounds composed of multiple continuous cycles. However, the sounds of Serrasalmus elongatus (higher number of cycles and high fundamental frequency) and S. manueli (long cycle periods and low fundamental frequency) are clearly distinguishable from the other species. The sonic mechanism being largely conserved throughout piranha evolution, acoustic communication can hardly be considered as the main driving force in the diversification process. However, sounds of some species are clearly distinguishable despite the short space for variations supporting the need for specific communication. Behavioural studies are needed to clearly understand the eventual role of the calls during spawning events
Interspecific variation of warning calls in piranhas: comparative analysis
Fish sounds are often considered as species-specific with unique temporal and spectral features. Differences between acoustic signals of closely related species could be considered as pre-zygotic barrier and could be related to the evolutionary history of the species. In the present study, sounds were recorded and compared in eight piranha species (Serrasalmus elongatus, Serrasalmus marginatus, Serrasalmus compressus, Serrasalmus manueli, Serrasalmus spilopleura, Serrasalmus rhombeus, Serrasalmus eigenmanni and Pygocentrus nattereri) in order to evaluate the potential role of acoustic communication as a driving force in the clade diversification. The same kind of sound-producing mechanism was found in all the species: sonic muscles originate on vertebrae and attach to a tendon surrounding ventrally the bladder. Contractions of the sound-producing muscles force swimbladder vibration. Having the same kind of sound-producing mechanism, the calling features of the eight piranha species show logically many common characteristics. In all the species, the calls are harmonic sounds composed of several pulses without inter-pulse interval. It was possible to discern species-specific sounds, but the differences among species could be, in part, explained by the size. Only the sounds of S. elongatus and S. manueli are really distinguishable from the other species. Serrasalmus elongatus differed by having a higher number of pulses and high-pitched fundamental frequency, whereas S. manueli differed by having long pulse periods and a low fundamental frequency. In the framework of this study, acoustic communication cannot be considered as the main driving force in the diversification process of piranhas. Behavioral studies are however needed to clearly understand the eventual role of the calls during the spawning events
Software Agents for Universal Design: An open software architecture to facilitate rapid-prototyping and enhance experience feedback
International audienc
Etude du vieillissement sur les productions langagiĂšres et sur les performances en reconnaissance automatique de la parole
International audienceâąCet article rapporte une Ă©tude sur lâutilisabilitĂ© dâun systĂšme de dictĂ©e vocale en français par des personnes ĂągĂ©es versus des personnes jeunes dans diverses situations de production vocale (dictĂ©es versus situation de parole spontanĂ©e). Notre hypothĂšse est que les performances des systĂšmes de reconnaissance pourraient ĂȘtre affaiblies dâune part, par le vieillissement de la voix et dâautre part, par les limites dâusage (essentiellement apprentissage et maĂźtrise de lâartefact technologique) par les personnes ĂągĂ©es. Diverses situations de production de parole sont Ă©tudiĂ©es afin de caractĂ©riser lâeffet du vieillissement et dâidentifier sâil y a des situations de production verbale et dâusage de technologies vocales plus « handicapantes » que dâautres. AprĂšs une brĂšve prĂ©sentation des consĂ©quences du vieillissement sur les processus cognitifs et perceptifs des personnes ĂągĂ©es, nous discutons les performances des systĂšmes de reconnaissance obtenues sur des Ă©noncĂ©s de personnes ĂągĂ©es. Nous procĂ©dons ensuite Ă une description du protocole expĂ©rimental. Les dĂ©gradations des performances du systĂšme sont corrĂ©lĂ©es au niveau de contrĂŽle du mode dâĂ©locution : plus le mode dâĂ©locution est libre, plus les performances sont mauvaises. Nos rĂ©sultats confirment ainsi lâeffet de lâĂąge du locuteur sur les performances de reconnaissance. Un autre rĂ©sultat intĂ©ressant concerne le fait que certaines classes de phonĂšmes telles que les voyelles antĂ©rieures et arrondies seraient plus susceptibles dâĂȘtre mal reconnues
FIG. 22 in Fishes of the Mitaraka Mountains (French Guiana)
FIG. 22. â Laimosemion geayi (Vaillant, 1889). Photograph: F. Melki.Published as part of <i>SĂ©bastien Brosse, FrĂ©deric Melki & RĂ©gis Vigouroux, 2019, Fishes of the Mitaraka Mountains (French Guiana), pp. 131-151 in Zoosystema 41 (8)</i> on page 149, DOI: 10.5252/zoosystema2019v41a8, <a href="http://zenodo.org/record/2639414">http://zenodo.org/record/2639414</a>
- âŠ