Résumé : La connaissance des facteurs qui influent sur les populations de tiques et en particulier sur leurs distributions est un préalable indispensable à l’étude des maladies qu’elles transmettent. Parmi eux, l’importance des facteurs biotiques et en particulier celle de la compétition interspécifique est peu connue et souvent négligée. L’objectif de ce travail était d’évaluer le rôle de la compétition interspécifique sur la distribution de deux espèces de tiques d’importance vétérinaire, Amblyomma variegatum et A. hebraeum. Alors que seule A. variegatum favorise la transmission de la dermatophilose, une maladie de peau débilitante pour les ruminants, les deux espèces sont vectrices de la cowdriose, maladie due à une bactérie Ehrlichia ruminantium qui représente une contrainte économique majeure pour l’élevage. L’impact de l’espèce vectrice dans l’épidémiologie de la cowdriose (différences de souches circulantes, sévérité des cas,…) est inconnu bien qu’ayant potentiellement des conséquences en termes de surveillance (risque épidémiologique à l’introduction d’animaux) et de contrôle (développement de vaccin régional adapté aux souches circulantes) de la maladie. Ces deux espèces ont une distribution contiguë en Afrique australe avec peu de chevauchement (distribution parapatrique) suggérant une préférence environnementale différentielle ou une compétition exclusive entre elles. Une revue des données de la littérature a permis de mettre en évidence un chevauchement de leur niche trophique, climatique, et temporelle, et une interférence comportementale via la production de leurs phéromones. Les deux espèces pourraient donc rentrer en compétition directement par interférence communicative ou reproductive (hybridation stérile), ou indirectement via le partage de ressources, prédateurs ou pathogènes communs. Le rôle des facteurs biotiques et abiotiques sur le maintien de la parapatrie de ces deux espèces a été analysée (i) d’une part par la comparaison de leur niche environnementale réalisée en Afrique australe, et aux deux zones de contact au Zimbabwe et Mozambique, par des méthodes d’ordination et de modèles de niche (Maxent) ; (ii) et d’autre part par l’étude de leurs distributions et de leurs interactions (distribution sur les hôtes, croisements hétérospécifiques) dans la zone de contact au Mozambique. Globalement les résultats montrent qu’en Afrique Sud-Est et au Zimbabwe les deux espèces occupent des niches environnementales distinctes, celle d’A. hebraeum incluant des zones plus chaudes et plus sèches que celle d’A. variegatum. Au contraire au Mozambique les deux niches se chevauchent considérablement. L’enquête de terrain dans cette zone montre que les deux espèces y sont moins souvent trouvées en sympatrie que les données prédites, suggérant une distribution en partie déterminée par des interactions biotiques. Dans les rares sites avec présence des deux espèces, A. variegatum et A. hebraeum partagent les mêmes sites de fixation sur les animaux et forment un pourcentage relativement élevé de couples hétérospécifiques. Ce pourcentage, bien que similaire entre les femelles A. variegatum et A. hebraeum, semble impliquer des processus de discrimination spécifique propres aux deux espèces intervenant au niveau de l’agrégation, de la fixation et du contact des individus. Nos résultats suggèrent l’existence d’une compétition exclusive entre les deux espèces, due à une compétition sexuelle probablement associée à une compétition indirecte. La frontière parapatrique semble occuper une position stable le long d’un gradient environnemental au Zimbabwe mais pas au Mozambique. Les conditions entrainant la coexistence ou l’exclusion des deux espèces avec formation d’une frontière parapatrique sont discutés à l’aide de modèles théoriques de compétition.
Studying the factors that influence tick populations and their distributions is an essential pre-requisite to understanding the dynamics of the diseases they transmit. The relative importance of biotic factors such as interspecific competition is not well known and often neglected. The objective of this study was to assess the influence of interspecific competition on the distribution of two tick species of veterinary importance, Amblyomma variegatum and A. hebraeum. Whereas only A. variegatum is known to favor dermatophilosis, a debilitating skin disease of ruminants, both species are good vectors of Ehrlichia ruminantium, the bacteria causing heartwater, a fatal disease of ruminants that presents a major constraint for livestock development in Africa. The impact of vector species in heartwater epidemiology (differences of circulating strains, severity of clinical cases…) is poorly known but may have important implications for surveillance (epidemiological risk of imported animals) and control (adapting regional vaccine programs to circulating strains) of the disease. These two ticks have abutting and marginally overlapping (i.e. parapatric) distributions in southern Africa, suggesting either differential environmental preferences or exclusive competition between the two species. A review of published data highlighted an important overlap of their trophic, climatic and seasonal niche, and existence of chemical behavior interference through pheromone production. Therefore, the two species might compete either directly by communicative or reproductive interference (sterile hybridization), or indirectly by sharing the same resources, predators or pathogens. The role of biotic and abiotic factors in determining parapatry of these species was assessed by (i) comparing their realized environmental niche in southern Africa, and at contact zones in Zimbabwe and Mozambique, using ordination techniques and environmental niche modeling (Maxent); (ii) studying their distributions and their interactions (distribution on co-infested host, heterospecific mating) at the contact zone in Mozambique. Globally, the results indicated the two species occupied distinctly different environmental niches in southern Africa and at the contact zone in Zimbabwe, with the niche of A. hebraeum including both hotter and drier areas than that of A. variegatum. However, in Mozambique their niches overlapped considerably. Field studies within this zone showed that sympatry was observed less frequently than predicted by niche models, suggesting an importance of biotic interactions. At the rare sites where both species were present, A. variegatum and A. hebraeum were observed to share the same preference sites on hosts and formed a high percentage of heterospecific pairs. Though this cross-mating rate was not significantly different between A. variegatum and A. hebraeum females, our observations suggest different mechanism of species discrimination involved for the two species acting at the aggregation, fixation and partner contact level. Our results strongly suggest exclusive competition between these species may arise from sexual competition probably interacting with other indirect forms of competition. The parapatric boundary apparently occupies a stable location along an environmental gradient at the contact zone in Zimbabwe but not in Mozambique. Conditions inducing coexistence or exclusion of both species with the formation of parapatric distributions are discussed in relation to theoretical models of competition. When sexual competition is introduced in these models, the relative frequency of two species is determined by their endogenous fitness (a function of environmental conditions), density dependent effects of competitive interactions, historical distributions and dispersal rates: survival of the first prevails when the immigration rate of a fitter invading species remains lower than an invasion threshold.

http://www.theses.fr/2014AGUY0705/document

Éditeur(s) : Université Bretagne Ouest
Résumé : This work deals with the fishing effects on the diversity dynamics of demersal fish communities, focusing on the biotic interactions. Multispecies indices are used in order to characterize the demersal fish community dynamics of the Bay of Biscay and of the Gulf of Lions. These are the diversity indices, the temporal variability of the total biomass and of the slope of the number size spectra and the slope of the species-area curves (spatial segregation). The yearly bottom trawl surveys EVHOE, CHALIST and MEDITS, carried out in these two areas since 1983 by IFREMER for the stocks assessment provide the data. The differences between areas are related to a fishing index (mean value of the annual landings of demersal fish per surface area). Other areas are included in the analysis when the index values are available from the published literature (North Sea, Scotian Shelf, Kenya, French Guyana). It is argued from the diversity indices analysis that the Gulf of Lions community is more diverse and less disturbed than the Bay of Biscay one. This result is not consistent with a fishing effect but with biogeography. The total biomass variability and the slope variability of size spectra are higher in the most harvested areas than in the least ones. On the contrary, the species-area slope is the lowest in the most harvested areas. Theoretically, biotic interactions decrease the total biomass variability and the spectra slope variability because of compensations and increase the species area slope because of competitive exclusion. It is concluded that harvesting alters biotic interactions and favour local coexistence by decreasing competitive exclusion. The species diversity maintenance depends on competitive exclusion. Hence, biodiversity is threatened not only by a direct fishing effect but also by a dynamics alteration.
Ce mémoire aborde le problème de l'impact de l'exploitation par la pêche sur la dynamique de diversité des peuplements de poissons démersaux. Les effets de la pêche sur le rôle des interactions biotiques entre espèces dans la dynamique des peuplements sont plus particulièrement analysés à l'aide de descripteurs multispécifiques. Les descripteurs utilisés sont les indices de diversité, la variabilité temporelle de la biomasse totale et de la pente multispécifique du spectre de poids et la pente des droites d'accumulation d'espèces mesurant la ségrégation spatiale. Les valeurs de ces indices sont calculées à partir des données de campagnes annuelles de chalutage de fond EVHOE, CHALIST et MEDITS, menées par l'IFREMER depuis 1983 pour l'évaluation des ressources halieutiques dans le golfe de Gascogne et dans le golfe du Lion. Les différences de caractéristiques de dynamique entre les deux peuplements révélées par ces descripteurs sont mises en relation avec un indice d'exploitation (valeur moyenne des débarquements annuels, divisée par la surface du plateau de la région concernée). D'autres régions ont été intégrées dans cette analyse lorsque les valeurs des indicateurs étaient disponibles dans la littérature (Mer du Nord, plateau de Nouvelle-Ecosse, Kenya et Guyane Française). Les indices de diversité utilisés permettent de mettre en évidence que le peuplement du golfe du Lion est plus diversifié et moins soumis à perturbations que celui du golfe de Gascogne. Ces caractéristiques semblent dues à l'histoire biogéographique de ces deux régions et non à un effet de la pêche. La variabilité de la biomasse totale et celle de la pente du spectre multispécifique augmentent depuis les régions les moins exploitées vers les plus exploitées. A l'inverse, la ségrégation spatiale diminue. En théorie, les interactions entre espèces diminuent la variabilité temporelle de la biomasse totale et de la pente du spectre multispécifique, à cause de compensations entre espèces, et augmentent la ségrégation spatiale par exclusion compétitive. L'interprétation donnée des résultats obtenus est ainsi une altération des interactions entre les espèces par l'exploitation. En prélevant de la biomasse, l'exploitation augmente la disponibilité des ressources pour les individus non pêchés. En conséquence, l'exclusion compétitive diminue et la coexistence locale des individus est facilitée. A long terme, la diversité est donc menacée, non seulement par raréfaction des espèces prélevées par l'exploitation mais aussi parce que les interactions sont altérées et que le maintien de la diversité en dépend pour partie.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2000/these-6670.pdf
http://archimer.ifremer.fr/doc/00000/6670/

Résumé : This label was created on October 20th 1900. Around the turn of the 20th century, cigars were advertised and sold mainly by the colourful, intricate labels that adorned the boxes. Intense competition encouraged manufacturers to see who could create the most beautiful, eye-catching labels. A diffrent stone was required to print each colour. It was not unusual for as many as 20 stones to be used to create a single label. The register for each printing had to be perfect. The process became known as STONE LITHOGRAPHY or CHROMOLITHOGRAPHY. Once this exacting printing process was completed, the labels were then gilded with hand-applied gold leaf. Finally, the labels were embossed using huge 30-ton presses. According to Joe Davidson, the eminent American art dealer and collector, the "Golden Era" of cigar labels is associated with the introduction of gilding and embossing in the 1890's up to the late 1920's when the less attractive full-colour or photo-mechanical labels began to appear. Genuine gold leaf was used primarily by German and Cuban printers and "bronzing" in which bronze powder was mixed with lacquer or sizing, applied like ink, then burnished with brushes or polished rollers to make them gleam like gold. These particular labels were produced by the German factory, Gerhard Meinesz in Bentheim, near the Dutch border, and closed in 1932. The labels were used during the 1920's. These spectacular lithographs lithographs wound up lying unused and undiscovered for generations. Because they were printed on special long-fibre, acid-free rage paper, these old labels retained their original brilliant colours. Consequently, they are available in very limited quantities.
(Funding) Funded in part by the Institute for Museum and Library Services (IMLS), Ephemeral Cities Project.
Tampa |z 1271000 |2 ceeus
Hillsborough County |z 12057 |2 ceeus
United States of America -- Florida -- Hillsborough County -- Tampa

Droits : All rights reserved. 2005.
C24-05393

Éditeur(s) : Institute of Jamaica. Institute of Jamaica. ( Kingston, Kingston )
Résumé : (Dates or Sequential Designation) Began with Dec. 1967 issue.
Note added on 12 August 2014: Jamaica Journal vol. 5, nos. 2-3; Error correction: On page 65 in this issue, the caption for a photograph of the art work “Back to Africa”, which won an award in the 1971 Jamaica Festival competition, states that the work was created by an anonymous artist. This piece was in fact executed by Jean Wilson, now Jean Wilson-Williams. We thank the artist for bringing this to our attention.
Jamaica
Jamaica

01797964
75027862
0021-4124
http://ufdc.ufl.edu/UF00090030/00014

Éditeur(s) : HAL CCSD
Résumé : International audience
This study investigated the possibility of there being differences in respiratory muscle strength and endurance in elite and competition triathletes who have similar maximal oxygen uptakes (V_O2max) and ventilatory thresholds (Thvent). Five internationally-ranked elite, [mean (SD) age 23.8 (1.4) years] and six nationallyand regionally-ranked competition [age 21.1 (1.1) years] male triathletes performed two successive trials: first an incremental cycle test to assess V_O2max and Thvent and second 20 min of cycling followed by 20 min of running (C-R) at intensities higher than 85% V_O2max. Cardioventilatory data were collected every minute during the two trials, using an automated breath-by-breath system. Maximal expiratory and inspiratory (PImax) strength were assessed before and 10 min after C-R from the functional residual capacity. Respiratory muscle endurance was assessed 1 day before and 30 min after C-R by measuring the time limit (tlim). The results showed firstly that during C-R, the competition triathletes had significantly (P<0.05) higher minute ventilation [mean (SEM) 107.4 (3.1) compared to 99.8 (3.7) lÆmin-1], breathing frequency [44.4 (2.0) compared to 40.2 (3.4) Æmin-1] and heart rate [166 (3) compared to 159 (4) beatsÆmin-1] and secondly that after C-R, they had significantly lower PImax [127.1 (4.2) compared to 130.7 (3.0) cmH2O] and tlim [2:35 (0:29) compared to 4:12 (0:20) min] than the elite triathletes. We conclude that, despite similar V_O2max and Thvent, the competition triathletes showed less extensive adaptive mechanisms, including those in the respiratory muscles, than did the elite triathletes. This led to higher ventilation, which appeared to be the cause of the faster development of fatigue in the inspiratory muscles in this group.
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY

hal-00720562
https://hal.univ-antilles.fr/hal-00720562
https://hal.univ-antilles.fr/hal-00720562/document
https://hal.univ-antilles.fr/hal-00720562/file/BoussanaEJAP02_2_.pdf

South America -- Guyana -- Georgetown
Caribbean

Éditeur(s) : CRILLASH : Centre de Recherches Interdisciplinaires en Lettres, Langues, Arts et Sciences Humaines
Extrait de : "Patrimonialisation et développement dans la Caraïbe et les Amériques" : colloque international, du 2 au 4 mars 2011. Université des Antilles et de la Guyane
Description : Historiquement le Carnaval cayennais avant les années 60 est créole, puis les vagues migratoires contribuent à créer un carnaval par groupes ethniques. Le carnaval est ainsi le reflet de la division ethnique de la Guyane, avec les créoles guyanais, les autochtones et les étrangers (dont antillais français et métropolitain). En effet, le discours sur la société guyanaise est une mosaïque de peuples, une société tolérante et métissée, fier de sa diversité et de sa multiculturalité. D'un simple défilé, il est devenu une grande parade où la compétition entre les groupes ethniques surtout le dimanche gras est forte. Le carnaval est alors une preuve d'intégration en définissant l'attitude a adopter pour se construire une identité et intégrer les frontières ethniques.
Siècle(s) traité(s) : 21
Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V12099
V12099

Éditeur(s) : HAL CCSD Thieme Publishing
Résumé : International audience
To determine the effect of triathlete performance level on the cardiorespiratory responses elicited by the cycle-run succession, eight regionally and nationally-ranked (Competitive) and five internationally-ranked (Elite) male triathletes underwent four successive laboratory trials: 1) an incremental treadmill test, 2) an incremental cycle test, 3) 30 min of cycling followed by 20 min of running (C-R), and 4) a 20-min control run (R) at the same speed as the run in C-R. Before and 10 min after the third and fourth trials the triathletes underwent lung function testing: spirometry and diffusing capacity testing for carbon monoxide (DL(CO)). During the C-R trial blood samples were drawn to measure venous lactate concentration. During all trials ventilatory data were collected every minute using an automated breath-by-breath system. The results showed that 1) the oxygen uptake (VO2) of post-cycling running versus running alone was similar for both groups; 2) the ventilatory responses (VE, VE/VO2, VE/VC02 and f) of C-R running versus R were significantly higher (P < 0.005) for the Competitive group; and 3) a significant decrease (P< 0.05) in DL(CO) was also noted after the C-R trial in the Competitive group but not in the Elite group. We concluded that 1) the ventilatory responses during a run subsequent to cycling may be related to the triathlete performance level, and 2) the C-R trial induced specific alterations in pulmonary function that may be associated with respiratory muscle alteration and exercise-induced hypoxemia in the Competitive triathletes.
ISSN: 0172-4622

hal-00720719
https://hal.univ-antilles.fr/hal-00720719

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : Intraguild predation (IGP) is a type of biological interaction involving the killing and consuming of competing species that exploit similar and often limited resources. This phenomenon is widespread among a great variety of taxonomic groups and has already been reported for mosquito (Diptera: Culicidae) larvae. Moreover, the larvae of certain mosquito species of the tribe Sabethini have evolved modified mouthparts ending in rigid apical structures signaling their capacity to be effective intraguild predators. We assumed that IGP confers a selective advantage under severe competitive conditions by both providing an immediate energetic gain and reducing potential competition. Because potential competition is likely to increase with decreasing habitat size, we hypothesized that the proportion of species with modified mouthparts would increase in smaller aquatic habitats. We tested this hypothesis by examining the mosquito species naturally associated with phytotelmata of decreasing sizes in French Guiana. We show that the degree of specialization in mosquito-phytotelm associations is high, suggesting a long coevolutive process. Indeed, short-term interaction experiments confirmed that species with modified mouthparts are able to prey upon similarly-sized intraguild prey and are, thus, effective intraguild predators. In addition, these species are larger and associated with smaller phytotelmata than those with typical mouthparts. Moreover, below a certain threshold of phytotelm size, only species with modified mouthparts were present. These results show that IGP confers a selective advantage under severe competitive conditions and results from the coadaptation of mosquito species to their specific phytotelm habitat. The presence of functionally analogous structures in different mosquito genera also implies that IGP has emerged from convergent evolution in small phytotelmata.
ISSN: 0269-7653

hal-01603304
https://hal.archives-ouvertes.fr/hal-01603304
DOI : 10.1007/s10682-016-9862-3
PRODINRA : 405771

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
In order to study the effect of a competitive triathlon season on maximal oxygen uptake (VO2max), aerobic power (AeP) and anaerobic performance (AnP) of the lower limbs, eight triathletes performed exercise tests after: (1) a pre-competition period (Pre-COMP) (2) a competitive period (COMP), and (3) a low (volume and intensity) training period (Post-COMP). The tests were a vertical jump-and-reach test and an incremental exercise test on a cycle ergometer. Ventilatory data were collected every minute during the incremental test with an automated breath-by-breath system and the heart-rate was monitored using a telemetric system. RESULTS: No changes in VO2max were observed, whereas AeP decreased after Post-COMP compared to Pre-COMP and COMP and AnP decreased during COMP compared to Pre-COMP and Post-COMP. In addition, second ventilatory threshold (VT2) and power output at first ventilatory threshold (VT1) and VT2 decreased after Post-COMP. CONCLUSION: This study showed that six weeks of low volume and intensity of training is too long a period to preserve adaptations to training, although a stable maximal oxygen uptake throughout the triathlon season was observed. Moreover, the AnP decrease during COMP was probably in relation with the repetitive nature of the training mode and/or triathlon competitions.
ISSN: 0905-7188

hal-00720811
https://hal.univ-antilles.fr/hal-00720811
https://hal.univ-antilles.fr/hal-00720811/document
https://hal.univ-antilles.fr/hal-00720811/file/Sms-10170.pdf

Éditeur(s) : Digital Library of the Caribbean Digital Library of the Caribbean ( Miami, Fla. )
Résumé : 1st place recipient in 1st Digital Library of the Caribbean (dLOC) Lesson Plan Competition

http://ufdc.ufl.edu/UF00094881/00001

Résumé : Label 7439 / 4 plates
Around the turn of the 20th century, cigars were advertised and sold mainly by the colourful, intricate labels that adorned the boxes. Intense competition encouraged manufacturers to see who could create the most beautiful, eye-catching labels. A diffrent stone was required to print each colour. It was not unusual for as many as 20 stones to be used to create a single label. The register for each printing had to be perfect. The process became known as STONE LITHOGRAPHY or CHROMOLITHOGRAPHY. Once this exacting printing process was completed, the labels were then gilded with hand-applied gold leaf. Finally, the labels were embossed using huge 30-ton presses. According to Joe Davidson, the eminent American art dealer and collector, the "Golden Era" of cigar labels is associated with the introduction of gilding and embossing in the 1890's up to the late 1920's when the less attractive full-colour or photo-mechanical labels began to appear. Genuine gold leaf was used primarily by German and Cuban printers and "bronzing" in which bronze powder was mixed with lacquer or sizing, applied like ink, then burnished with brushes or polished rollers to make them gleam like gold. These particular labels were produced by the German factory, Gerhard Meinesz in Bentheim, near the Dutch border, and closed in 1932. The labels were used during the 1920's. These spectacular lithographs lithographs wound up lying unused and undiscovered for generations. Because they were printed on special long-fibre, acid-free rage paper, these old labels retained their original brilliant colours. Consequently, they are available in very limited quantities.
(Funding) Funded in part by the Institute for Museum and Library Services (IMLS), Ephemeral Cities Project.
Tampa |z 1271000 |2 ceeus
Hillsborough County |z 12057 |2 ceeus
United States of America -- Florida -- Hillsborough County -- Tampa

Droits : All rights reserved. 2005.
C24-05394

Éditeur(s) : HAL CCSD
Résumé : International audience
The aim of this study was to examine the heart rate (HR) response to Olympic windsurfing competition and to check if there was any correlation between racing HR, performance, and the variables measured during laboratory maximal exercise. Ten elite windsurfers [age: 20.93 (3.46) years; height: 178.10 (6.34) cm; body mass: 66.79 (5.90) kg] performed a laboratory maximal oxygen consumption (VO2max) trial and national windsurf competitions wearing a HR monitor. One hundred and forty-three individual races were examined. Racing HR was expressed as a percentage of (1) HRmax (maximal treadmill HR) and (2) HRreserve (HRmax)HRrest). The performance (racing classification: RC, which is inversely proportional to performance) was significantly correlated to the racing HR response in both light wind (LW): LW)RC=)0.12(%HRreserve)+13.03; r=)0.71, r2=0.50, p<0.001, and medium wind (MW): MW)RC=)0.11(%HRreserve)+10.99; r=)0.66, r2=0.43, p<0.001. The results showed similar correlations between performance and %HRmax. Post racing lactate concentration was higher in LW compared to MW [7.14 (0.21) and 5.18 (2.02) mmolÆl)1, respectively]. There was a negative correlation between the highest racing HR (%HRreserve) of each athlete and the second ventilatory threshold expressed as a percentage of VO2max (r=-0.71, p<0.05). To summarize, this study showed that light and medium wind Olympic windsurfing performances are highly dependent on the capacity of the athlete to maintain a high HR for long periods of time. Furthermore, windsurfing is highly dependent on the athlete's physical fitness level as shown by the correlations between racing HRs and laboratory physiological variables.
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY

hal-00720564
https://hal.univ-antilles.fr/hal-00720564
https://hal.univ-antilles.fr/hal-00720564/document
https://hal.univ-antilles.fr/hal-00720564/file/Chamari_Wind_surf_and_Heart_rat.pdf

Éditeur(s) : HAL CCSD Springer Verlag/EDP Sciences
Résumé : International audience
Context : Functional - structural models (FSM) of tree growth have great potential in forestry, but their development, calibration and validation are hampered by the difficulty of collecting experimental data at organ scale for adult trees. Due to their simple architecture and morphological properties, " model plants " such as Cecropia sciadophylla are of great interest to validate new models and methodologies, since exhaustive descriptions of their plant structure and mass partitioning can be gathered. * Aims : Our objective was to develop a model-based approach to analysing the influence of environmental conditions on the dynamics of trophic competition within C. sciadophylla trees. * Methods : We defined an integrated environmental factor that includes meteorological medium-frequency variations and a relative index representing the local site conditions for each plant. This index is estimated based on model inversion of the GreenLab FSM using data from 11 trees for model calibration and 7 trees for model evaluation. * Results : The resulting model explained the dynamics of biomass allocation to different organs during the plant growth, according to the environmental pressure they experienced. * Perspectives : By linking the integrated environmental factor to a competition index, an extension of the model to the population level could be considered.
ISSN: 1286-4560

hal-00780347
https://hal-ecp.archives-ouvertes.fr/hal-00780347
https://hal-ecp.archives-ouvertes.fr/hal-00780347/document
https://hal-ecp.archives-ouvertes.fr/hal-00780347/file/Letort2011AFS.pdf
DOI : 10.1007/s13595-011-0131-x

Éditeur(s) : [s.n.] [s.n.] ( Quezaltenango Guatemala City )
Résumé : On cover: Bases.
At head of title: Junta mantenedora.
Guatemala
Central America

AHH0766
22587512
001557129

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
Objectifs. - Évaluer les effets du triathlon classique (1,5 km natation, 40 km cyclisme, 10 km course à pied) sur la capacité de diffusion pulmonaire (DLCO) 24 heures après la compétition. Méthodes et résultats. - Dix triathlètes masculins (21,5 ± 2,8 ans) ont effectué une spirométrie et une mesure de la capacité de diffusion pulmonaire avant la compétition (pré-T) et 24 heures après l'épreuve (post-T). Les résultats montrent une diminution significative du volume expiratoire maximal en 1 s (5,17 ± 0,4 L.s-1 contre 4,09 ± 0,6 L.s-1) et du débit expiratoire maximal 25-75 % de la capacité vitale (6,98 ± 0,2 L.s-1 contre 4,90 ± 0,2 L.s-1). En revanche, les résultats ne montrent pas de différence significative entre les DLCO pré-T et post-T (38,1 ± 3,3 mL.min-1.mmHg-1 contre 37,1 ± 3,7 mL.min-1.mmHg-1) ni les ratios DLCO/VA (5,59 ± 0,5 mL.min-1.mmHg-1.A-1 contre 5,55 ± 0,7 ml.min-1.mmHg-1.A-1). Conclusion. - La DLCO est normale chez les triathlètes 24 heures après une compétition classique. Ceci peut traduire l'absence de lésions alvéolocapillaires pendant le triathlon. La baisse de la DLCO rapportée deux heures après un exercice dans la littérature peut s'expliquer par la baisse du volume sanguin pulmonaire qui apparaît comme un phénomène transitoire. Cependant, la baisse des débits pulmonaires observée 24 heures après le triathlon suggère la persistance chez les triathlètes d'un syndrome obstructif bronchique.
ISSN: 0765-1597

hal-00720522
https://hal.univ-antilles.fr/hal-00720522
https://hal.univ-antilles.fr/hal-00720522/document
https://hal.univ-antilles.fr/hal-00720522/file/Article_3_.pdf

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Microalgae in the division Haptophyta play key roles in the marine ecosystem and in global biogeochemical processes. Despite their ecological importance, knowledge on seasonal dynamics, community composition and abundance at the species level is limited due to their small cell size and few morphological features visible under the light microscope. Here, we present unique data on haptophyte seasonal diversity and dynamics from two annual cycles, with the taxonomic resolution and sampling depth obtained with high-throughput sequencing. From outer Oslofjorden, S Norway, nano- and picoplanktonic samples were collected monthly for 2years, and the haptophytes targeted by amplification of RNA/cDNA with Haptophyta-specific 18S rDNA V4 primers. We obtained 156 operational taxonomic units (OTUs), from c. 400.000 454 pyrosequencing reads, after rigorous bioinformatic filtering and clustering at 99.5%. Most OTUs represented uncultured and/or not yet 18S rDNA-sequenced species. Haptophyte OTU richness and community composition exhibited high temporal variation and significant yearly periodicity. Richness was highest in September-October (autumn) and lowest in April-May (spring). Some taxa were detected all year, such as Chrysochromulina simplex, Emiliania huxleyi and Phaeocystis cordata, whereas most calcifying coccolithophores only appeared from summer to early winter. We also revealed the seasonal dynamics of OTUs representing putative novel classes (clades HAP-3-5) or orders (clades D, E, F). Season, light and temperature accounted for 29% of the variation in OTU composition. Residual variation may be related to biotic factors, such as competition and viral infection. This study provides new, in-depth knowledge on seasonal diversity and dynamics of haptophytes in North Atlantic coastal waters. See also the Perspective by Massana
ISSN: 0962-1083

hal-01545321
https://hal.archives-ouvertes.fr/hal-01545321
DOI : 10.1111/mec.13160

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Predicting the impact of underground engineering on the environment requires the knowledge of natural media at different scales. In particular, understanding basic phenomena controlling the properties of rocks in the presence of complex fluids necessitates a detailed atomic description of the solid/fluid/solid contacts, the subject of Part I of the present study. First, building the solid interspace between two different crystals in a non-periodic situation is achieved using the ab initio and molecular mechanics code GenMol (TM). A description of the fluid confined within the interspace is then derived from the original genetic iterative multi-species (GIMS) algorithm implemented in the same code. This approach consists of equilibrating chemical potentials, cycle after cycle and species after species, between the confined fluid and the free natural fluid. An elementary iteration for a species k consists of different steps incrementing the number N-k of particles k, with other numbers N-k remaining constant. At each step, an optimum fluid composition is obtained by a genetic process distributing the fluid particles on a grid by stochastic shots, followed in fine by a refining process. The effectiveness of the GIMS approach is demonstrated in the case study of a fluid confined between two (0 0 1) kaolinite faces, with apertures h varying between 4 and 10 A. connected to a 9-species external solution [H2O, Cl-, Na+ CO2(aq), NaCl(aq), Ca2+, Mg2+, HCO3-, H3O+] where concentrations are ranging from 55 to 10(-4) mol/L. The results show a drastic variation in the solute/solvent and cations/ions ratios in the confined fluid when aperture h is lowered to less than 1 nm. These results obtained with a very rapid convergence of the iterative algorithm combined with a very competitive genetic optimizer are validated with high precision on a free solution. This description of contacts between crystals is original and unattainable by standard crystal interface approaches. It opens the way to understanding and/or predicting phenomena between crystals in a complex natural environment, such as adhesion or repulsion investigated in the Part II of this study.
ISSN: 0022-0248

hal-00544569
https://hal.archives-ouvertes.fr/hal-00544569
DOI : 10.1016/j.jcrysgro.2010.08.009

Éditeur(s) : Université de Paris 7
Résumé : The Seine estuary and its adjacent region Pays de Caux are two significant sources of mercury for coastal marine environments. It is carried through fluvial means for the Seine bay and through karstic fresh water emergences for Pays de Caux's coastal area. Mercury cycle in the Seine estuary and bay is affected by additional anthropical activities. The estuary's maximal turbidity area acts like a trap and a chemical reactor for fluvial mercury. Within this area, we can confirm: (i) the non conservative behaviour of dissolved mercury; (ii) mercury enrichment of particles when comparing the Seine's and marine environment and we suggest mercury particle redistribution from the organic fraction to the oxyhydroxydes fraction. A large fraction of mercury is exported in this state towards coastal areas. Mercury reduction in surface coastal waters and its atmospherical recycling are major phenomena. Photoreduction and biological reduction play quantitative roles equivalent to total mercury recycling via the atmosphere corresponding approximately to 30 % of fluvial exchanges. We are demonstrating that reactive forms of mercury are supporting photoreduction. Mercury behaviour within Pays de Caux's karst depends of the hydrogeological context of the system (time and flow speed, turbidity, flow); regardless of the speciation and/or partition in underground waters, the total amount of mercury in intertidal areas is quantitatively the same as in the Seine estuary. Mercury brought through intertidal emergences (karstic exudations) is not « filtered » by a maximal turbidity area and is more widely bio-available for mussels than in the Seine estuary. Even being free from growth factor influences through simple models, mussels found in Pays de Caux still show one of the highest mercury contamination on the French coast; for the first time this places the emphasis on how much mercury is brought from underground waters to the coastal environment. Surface complexation modelisation tests are able to reproduce the major part of mercury partition in the Seine estuary and bay if a very low mercury exchangeable fraction and minimum complexation parameters are taken into account; thermodynamic calculations also suggest that a strong or highly concentrated « dissolved » ligand must be present in the water in order to compete with chlorocomplex formations and explain our measures.
L'estuaire de la Seine et la région adjacente du Pays de Caux sont deux sources significatives en mercure pour le milieu marin côtier. Les apports sont d'une part fluviatiles en ce qui concerne la Baie de Seine et karstiques via des émergences d'eau douce pour la zone côtière du Pays de Caux. Le cycle du mercure en estuaire et baie de Seine est perturbé par les apports liés aux activités anthropiques. La zone de turbidité maximum de l'estuaire joue le rôle de piège et de réacteur chimique pour le mercure fluviatile. Au sein de cette zone, nous mettons en évidence : (i) un comportement non-conservatif du mercure dissous; (ii) un enrichissement en mercure des particules par rapport à celles de la Seine et du milieu marin et suggérons une redistribution du mercure particulaire de la fraction organique vers la fraction oxyhydroxydes. C'est sous cette forme qu'une fraction importante du mercure est exportée vers la zone côtière. La réduction du mercure dans les eaux côtières de surface et son recyclage atmosphérique sont des phénomènes majeurs. En effet, la photoréduction et la réduction biologique jouent des rôles quantitativement équivalents avec un recyclage total du mercure via l'atmosphère correspondant à environ 30% des apports fluviatiles. Nous montrons que les formes réactives du mercure constituent le substrat de la photoréduction. Le comportement du mercure au sein du karst du Pays de Caux dépend du contexte hydrogéologiques du système (temps et vitesse de circulation, turbidité, débit) ; quelle que soit la spéciation et/ou la partition dans les eaux souterraines, l'apport en mercure total à la zone intertidale est quantitativement du même ordre de grandeur que les apports de la Seine. Le mercure apporté par les émergences intertidales (exutoires karstiques) n'est pas « filtré » par une zone de turbidité maximale et se trouve plus largement biodisponible pour les moules qu'en estuaire de Seine. En s'affranchissant, par des modèles simples, de l'influences des facteurs de croissance, les moules du Pays de Caux affichent toujours une contamination par le mercure parmi les plus élevées du littoral français; ceci met pour la première fois l'emphase sur l'importance de l'apport en mercure par des eaux souterraines dans un environnement côtier. Les essais de modélisation de complexation de surface reproduisent la majeure partie de la partition du mercure dans l'estuaire et la baie de Seine si l'on tient compte d'une fraction échangeable en mercure très faible et de paramètres de complexation minimums ; les calculs thermodynamiques suggèrent aussi qu'un ligand « dissous » fort ou présent à de fortes concentrations doit être présent dans l'eau afin d'entrer en compétition avec la formation de chlorocomplexes et expliquer nos mesures.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2001/these-1842.pdf
http://archimer.ifremer.fr/doc/00000/1842/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Despite the increasing dominance of turf algae in coral reefs, few studies have investigated their physiological and ecological responses to changes in abiotic factors. We tested the effects of depth and ultraviolet radiation on turf algae at different levels of successional stages using two experiments. Depth-related differences were found for all turf algal communities, characterized by a higher amount of the cyanobacteria taxon Dichothrix and the red filamentous genera Poly-/Herposiphonia in the shallow and the appearance of oscillating cyanobacteria in deeper waters. In the first experiment, cross-depth transplantation of 153 days old communities influenced percentage cover, biomass and taxa composition. Downward transplantation lowered overall biomass and abundance of the foraminifera Sorites, whereas the crustose green alga Pringsheimiella and filamentous cyanobacteria colonized the communities. A nearly reverse pattern was observed in upward transplanted communities. Overall we distinguished between sensitive taxa, like Oscillatoria, and taxa able to acclimate to alterations in their environment, like Pringsheimiella, Poly/Herposiphonia and Dichothrix. In the second experiment, algae grown for 285 days at 5 m were exposed together with a set of sterile settlement tiles to three UVR regimes at 2 m for 22 days. UVR had no effect on turf algal communities regardless of successional stage. This study highlights the presence of high light and UV tolerant species. The high UV tolerance of turf communities may confer a competitive advantage over other more sensitive coral reef biota, such as corals. This study demonstrates that turf algae are dynamic communities exhibiting species-specific resistance to environmental changes.
ISSN: 0022-0981

hal-01333486
https://hal-univ-perp.archives-ouvertes.fr/hal-01333486
DOI : 10.1016/j.jembe.2014.07.017