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1
Valembois, J. "ETUDE SUR MODELE DU TRANSPORT LITTORAL CONDITIONS DE SIMILITUDE". Coastal Engineering Proceedings 1, n.º 7 (29 de enero de 2011): 18. http://dx.doi.org/10.9753/icce.v7.18.
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L*objet do la pr^sente note est d*e"tudier les conditions'de similitude que l'on obtient, pour la representation sur modele du transport littoral, a partir de divers criteres, Les re"sultats concernent les plages form^es de sable fin, a 1*exclusion des plages de galets et des zones ou la vase existe en proportions importantes.
Le premier critere examine" est la reproduction du debut d* entratnement des mate'riaux de fond sous 1' action du mouvement oscillatoire de 1'eau dft a la houle, la oouche limite etant suppos^e laminair* dans la nature et sur lemodele.
Les re"sultats obtenus sont ensuite etendus h la representation du de*but d* entraliiement sous l1action du courant de transport de masse perpendiculaire a la plage, ffifene lorsque cet ecoulement est turbulent au voisinage du fond. La representation correcte du debut d* entratnement conduit probablement a une bonne concordance entre le modele et la nature pour la zone situe"e Men au large du de"ferlement, mais il n'est pas du tout Evident (et il serait m&me etonnant) qu'elle permette d'obtenir sur le modele un transport littoral ressemblant au transport naturel dans les zones voisin.es du deferlement et pres du rivage. En effet, les phenomenes hydrauliques sont tout a fait differents dans ces regions, ou interviennent de facon preponderante la turbulence cr^ee par le deferlement, les courants de masse perpendiculaires et paralleles a la cdte, et probablement la percolation dans la zone de l'estran, ainsi que1*action du vent sur la surface de l'eau.
Pour aller un peu plus loin, on a essaye de definir les conditions dans lesquelles le mouvement des materiaux en suspension est correctement represente sur le modele.
La connaissance incomplete oue l'on a actuellement des lois du transport littoral ne permet pas de decider a priori si les criteres retenus sont valablesj cependant, on est arrive dans divers Laboratoires, avec des modeles dont les echelles etaient voisines de celles auxquelles on aboutirait de cette facon, a representer des transports littoraux assez semblables a ceux de la nature. On verra d'ailleurs que les conditions auxquelles on arrive laissent quelque liberte dans le choix des echelles. Cette liberte a probablement ete utilisee dans le bon sens sur les modeles en question.
2
Tsai, Chien Hsiung, Yao Nan Wang, Chang Hsien Tai, Jr Ming Miao y Jik Chang Leong. "Effects of Heating Vents in a Tunnel-Type Dryer". Advanced Materials Research 189-193 (febrero de 2011): 1757–60. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1757.
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This work employs FDS to simulate the heating process of a tunnel-type dryer and visualizes the computational results using Smokeview. The inappropriate design of a tunnel-type dryer in a factory has motivated this work. This poorly designed dryer not only has caused terrible fuel consumption but also produced parts some of which are under- or over-cooked. These are caused by the terribly uneven temperature distribution within the dryer. In order to improve the evenness of temperature distribution, this work simulates and investigates the effects of various ventilation schemes. Based on the results, it is found that the hot air intake vent should be placed at the bottom whereas the cold air outtake vent at the top. The flow rate through the intake vents does not have a very significant effect on the temperature distribution after 40 s.
3
Tan, Felicia, Vincent Tam y Chris Savvides. "Elevated LNG Vapour Dispersion—Effects of Topography, Obstruction and Phase Change". Eng 2, n.º 2 (15 de junio de 2021): 249–66. http://dx.doi.org/10.3390/eng2020016.
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The dispersion of vapour of liquefied natural gas (LNG) is generally assumed to be from a liquid spill on the ground in hazard and risk analysis. However, this cold vapour could be discharged at height through cold venting. While there is similarity to the situation where a heavier-than-air gas, e.g., CO2, is discharged through tall vent stacks, LNG vapour is cold and induces phase change of ambient moisture leading to changes in the thermodynamics as the vapour disperses. A recent unplanned cold venting of LNG vapour event due to failure of a pilot, provided valuable data for further analysis. This event was studied using CFD under steady-state conditions and incorporating the effect of thermodynamics due to phase change of atmospheric moisture. As the vast majority of processing plants do not reside on flat planes, the effect of surrounding topography was also investigated. This case study highlighted that integral dispersion model was not applicable as key assumptions used to derive the models were violated and suggested guidance and methodologies appropriate for modelling cold vent and flame out situations for elevated vents.
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Bachand, Étienne y Sophie Comtois. "Recharge en sable et revégétalisation de 2 plages de l’estuaire du Saint-Laurent, Québec". Le Naturaliste canadien 140, n.º 2 (2 de junio de 2016): 105–12. http://dx.doi.org/10.7202/1036508ar.
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En 2012, le comité ZIP (Zone d’intervention prioritaire) du Sud-de-l’Estuaire a réalisé 2 projets de recharge en sable sur des plages du Bas-Saint-Laurent. C’est respectivement 275 m3 et 295m3 de sédiments qui ont été déposés sur une plage de Sainte-Flavie et de Rivière-Ouelle. Les recharges en sable étaient accompagnées d’une revégétalisation à l’aide d’espèces indigènes possédant une forte capacité de rétention des sols. Ces techniques souples de restauration des berges s’appuient sur le principe de la dynamique naturelle des écosystèmes côtiers pour atténuer les effets de l’érosion littorale et diminuer les dégâts liés à la submersion marine. Sur chacun des sites, 100 m linéaires de plage ont été restaurés pour une fraction (453 $/m linéaire) des coûts nécessaires à la construction d’un enrochement (7 000 $/m linéaire). Après 3 années de suivi, on a noté un engraissement et un élargissement des plages ainsi qu’un développement rapide des végétaux dans le milieu. La restauration des écosystèmes littoraux est une solution durable, écologique, peu coûteuse et accessible aux communautés côtières.
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Ritchot, Gilles y André Cailleux. "Taxonomie, géomorphologie et morphoscopie de sables au Québec méridional". Cahiers de géographie du Québec 15, n.º 36 (12 de abril de 2005): 423–38. http://dx.doi.org/10.7202/020980ar.
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La connaissance préalable de la géomorphologie permet de récolter à bon escient des échantillons de sables, tills, matrice de graviers, arènes de désagrégation. L'étude au microscope binoculaire, par réflexion, des grains de quartz de 0,5 à 1 millimètre, de formations quaternaires ou actuelles du Québec méridional, montre la prédominance des grains non-usés (moyennes : 73 à 95%), normale au voisinage du bouclier et de montagnes ; la présence de grains remaniés façonnés par le vent au Paléozoïque, surtout dans les Appalaches (11%) et les Basses terres (6%), moins abondants dans les Laurentides (2%) ; l'absence presque générale de trace d'usure dans l'eau, sauf dans les sables d'estuaire ou de plages marines (5%) et dans les sables éoliens qui souvent en dérivent (3%) ; enfin la présence de grains façonnés par le vent quaternaire et actuel, surtout dans les sables éoliens (15%) ; dans les autres sortes de dépôts, il y en a bien moins (1 à 2%). Dans le détail, aux îles de la Madeleine et ailleurs, ces résultats sont en très bon accord avec ceux de l'étude géomorphologique. Et la morphoscopie (étude de la forme des grains) apporte ainsi une contribution utile à la géographie physique, dans les cas difficiles en particulier.
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Salmon, Camille y Virginie K. E. Duvat. "Enjeux de l'intégration des espaces naturels littoraux dans la gestion des risques liés à la mer". La Houille Blanche, n.º 2 (abril de 2018): 5–12. http://dx.doi.org/10.1051/lhb/2018015.
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En se basant sur deux études de cas situées dans l'outre-mer français, cet article traite de l'intégration des espaces naturels littoraux dans la gestion des risques liés à la mer. L'étude des impacts de et de la résilience aux cyclones Oli (février 2010) à Tubuai (Polynésie française) et Bejisa (janvier 2014) à la Réunion, a mis en évidence le rôle majeur de la dégradation de la zone tampon (systèmes plages-dunes dans notre étude) dans l'augmentation de la vulnérabilité. Cinq processus de dégradation sont analysés : la contraction (diminution de la surface), la fragmentation des cellules hydro-sédimentaires par des aménagements côtiers, la fixation du trait de côte par des ouvrages de défense, le défrichement et la modification de la végétation et enfin l'extraction de matériaux coralliens sur les plages. Ces phénomènes ont pour conséquence la perturbation de la fonction d'amortissement des vagues et du vent, ce qui au final augmente l'endommagement des enjeux humains lors de la survenue d'un événement météo-marin extrême. Ces résultats ont des implications concrètes pour favoriser la résilience des territoires face aux risques liés à la mer : (1) mener une politique de protection et/ou de restauration des espaces naturels littoraux, (2) considérer la cellule hydro-sédimentaire comme l'échelle d'intervention pertinente, (3) mettre en œuvre des mesures différenciées qui prennent en compte le long terme, afin d'engager dès maintenant une politique d'adaptation au changement climatique.
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Piton, Guillaume, Simon Carladous, Olivier Marco, Didier Richard, Frédéric Liebault, Alain Recking, Yann Queffelean y Jean-Marc Tacnet. "Usage des ouvrages de correction torrentielle et plages de dépôt : origine, état des lieux, perspectives". La Houille Blanche, n.º 1 (febrero de 2019): 56–67. http://dx.doi.org/10.1051/lhb/2019008.
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La correction torrentielle des torrents les plus actifs a été lancée en France par la politique de restauration des terrains en montagne de 1882 sur la base de travaux pionniers plus anciens. Elle a d'abord mis à profit la correction active des hauts bassins par la lutte contre l'érosion à la source mais a aussi accompagné le développement de la protection passive des enjeux par le piégeage et la canalisation des écoulements dans les zones aval. Cette lutte contre l'érosion et les risques torrentiels induits fait toujours l'objet d'investissements publics pour entretenir les systèmes de protection existants et, si nécessaire, en construire de nouveaux. Les contextes environnementaux, socio-économiques et techniques d'implantation et de gestion de ces systèmes de protection ont évolué. Il y a donc matière à s'interroger sur l'usage actuel qui est fait des ouvrages de correction torrentielle et des plages de dépôts, ouvrages spécifiques au contexte torrentiel. Cet article rappelle en premier lieu un historique de leur émergence. La seconde partie liste les fonctions de ces ouvrages : quels effets qualitatifs pouvons-nous espérer de ces structures à la lumière de plus de 150 ans d'expérience ? La dernière partie donne quelques perspectives concernant l'usage de ces ouvrages : pourquoi faut-il maintenir une part de correction active malgré les difficultés associées ? Qu'est-ce qui peut justifier d'abandonner ou de détruire certains ouvrages ? Quelles nouvelles approches semblent émerger dans la conception de ces ouvrages, et plus particulièrement des plages de dépôt modernes.
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Huang, Biao, Shiqiang Wu, David Z. Zhu y Fangfang Wang. "Mitigating peak pressure of storm geysering by orifice plates installed at the top of vent pipes". Water Science and Technology 78, n.º 7 (15 de octubre de 2018): 1587–96. http://dx.doi.org/10.2166/wst.2018.436.
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Abstract Large air pockets can be trapped in storm sewer systems during intense rain events. Uncontrolled release of these air pockets may cause geysering and pressure surges, resulting in flooding, pipe failures and safety issues. Thus, there is a great need to develop methods to retrofit existing sewer systems and to provide guidance on system design. A large-scale physical model was established to evaluate air-control orifice plates in reducing geysering intensity by utilizing air cushion effects over the process of air escape. Experimental results indicate that the magnitude of pressure fluctuations can be reduced significantly with partially open vent pipes. The maximum pressure head can be reduced by approximately two-thirds, and the magnitude of relative pressure oscillation decreased by about 95% when the diameter ratio of the air-control orifice to the vent pipe is below 25%. Air–water mixture jets can be avoided in such cases. The effect of using multiple vent pipes with orifice plates was also evaluated and found to be effective. Thus, air-control vent pipes can be applied to alleviate geysering and related pressure transients.
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Troutot, Pierre-Yves. "Les travailleurs sociaux, la dynamique de l’impuissance et les modèles professionnels : une mise en perspective". Travailler le social, n.º 7 (3 de febrero de 2016): 71–82. http://dx.doi.org/10.7202/1035011ar.
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Cet article propose une typologie des modèles professionnels sous-tendue de quatre logiques de positionnement, par rapport auxquelles les pratiques des travailleurs du social peuvent être situées. Cette schématisation part du sentiment de malaise et d’impuissance ressenti par les travailleurs sociaux, en prenant en compte la question de leur pouvoir et des effets sociaux de leurs attitudes de dépassement. Les modèles théoriques proposés résultent de l’interrelation entre deux axes : d’une part la tension entre l’engagement éthique et la recherche de sécurité dans l’emploi et, de l’autre, la tension entre la recherche de promotion sociale et de solidarité culturelle et politique avec les usagers. D’où un schéma dont les plages indiquent des positionnements socio-philosophique, socio-économique, socio-professionnel et socio-politique. Logiques et modèles, enfin, qui caractérisent le travailleur social en tant que « technicien » (logique de la professionnalisation), « fonctionnaire » (logique de la bureaucratisation), « salarié-militant » (logique de la déprofessionnalisation) et « médiateur-convivial » (logique de la désinstitutionnalisation).
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Kato, Hayato, Kotaro Takamure y Tomomi Uchiyama. "Characteristics of vortex shedding in the wake of a sphere with a uniaxial through-hole". AIP Advances 12, n.º 10 (1 de octubre de 2022): 105112. http://dx.doi.org/10.1063/5.0098762.
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Wake flows have significant effects on vehicles, buildings, and other objects encountered in daily life. Thus, wake control techniques are of practical importance and have been extensively investigated. One passive wake-control technique is to create a vent on a bluff body, which has been determined to be effective for wake control on a circular cylinder but has not been sufficiently studied for wake control on a sphere. Therefore, this study examined the effect of the vent angle on the characteristics of the wake of a sphere. A sphere with a uniaxial through-hole (vent) was placed in a uniform flow, and the vent angle was varied in the streamwise direction. The Strouhal number in the high-frequency and low-frequency modes was examined. The flow field in the sphere wake varied with respect to the vent angle. Three frequency modes (high, low, and very low), the occurrence of a switching phenomenon, wherein the velocity fluctuated between positive and negative values, and high-frequency energy injection by the vent were observed. In addition, a high dominant frequency was observed only in the positive velocity fluctuation region.
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Benazieb, Brahem y Zoubir Nemouchi. "Simulation d’un écoulement d’air projeté sur un profil de pale d’éolienne avec générateurs de vortex". Journal of Renewable Energies 18, n.º 1 (18 de octubre de 2023): 127–41. http://dx.doi.org/10.54966/jreen.v18i1.490.
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Le présent travail est une contribution à l'étude par simulation numérique de la dynamique de l’air à travers des générateurs de vortex contre rotatifs sur un profil de la pale d’éolienne urbaine ‘FX-63-137’ à l’aide du code de calcul –Fluent-, en utilisant le modèle de turbulence (k-E), en régime permanent et incompressible avec un nombre de Reynolds Re=105. Les effets de la géométrie des générateurs de vortex et leurs positions par rapport au profil ont été mis en évidence. La première partie du travail traite de l’écoulement autour du profil avec les générateurs de vortex pour un certain angle d’attaque et la solution 3D avec générateur de vortex est comparée à celle de l’écoulement autour d’un profil 2D plan sans générateur de vortex. La deuxième partie de ce travail traite des effets du changement de la position des générateurs de vortex (GV) et l’angle d’incidence du vent par rapport au profil, pour les cas sans et avec générateurs de vortex sur les forces de portance et de traînée induites.
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Chassefière, Éric. "Interprétation des variations barométriques au tournant du xviiie siècle : effets de l’élasticité de l’air". Mathématiciens français au travers de la Grande Guerre III-16 (2024): 271–93. http://dx.doi.org/10.4000/11qwr.
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Le fait que le baromètre monte par beau temps, quand l’atmosphère est claire, et descende par mauvais temps, quand le ciel est chargé, intrigue les savants dès les premières mesures réalisées au milieu du xviie siècle. L’intuition naturelle est en effet que le poids de la colonne d’air pesant sur le mercure devrait augmenter quand les vapeurs s’élèvent dans l’atmosphère, et diminuer quand elles retombent en pluie. Par ailleurs, on semble mettre en évidence une tendance du baromètre à monter plus haut par temps froid et en hiver. Les hypothèses faites pour expliquer ces observations portent sur des paramètres tels que le vent, la pluie et l’élasticité de l’air. Nous analysons ici les hypothèses relatives à ce dernier paramètre, et les replaçons dans le contexte de l’évolution des idées sur la nature du système atmosphérique.
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Huang, Yong, Zibiao Luo, Yan Tang y Wenhui Deng. "Analysis of the Impact of Lateral Conduit and Metal Wire Mesh on Methane Explosions". Processes 11, n.º 12 (18 de diciembre de 2023): 3446. http://dx.doi.org/10.3390/pr11123446.
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To enhance the deflagration efficiency and protection level of combustible mixed gases in narrow spaces, a small square experimental pipeline system was designed. Experiments were conducted to investigate the effects of lateral vent pipes and metal wire meshes on the explosion characteristics of methane gas. This study examined the influence of changing the positions of the lateral vent pipes and metal wire meshes in the pipeline on the variation of parameters such as the flame shape, leading speed, and pressure of the methane/air premixed gas in the pipeline. The results indicated that the lateral vent pipes could effectively release part of the energy from the methane explosion, and the release effect was stronger the closer they were to the ignition end. This was significantly more effective in releasing the flame and pressure than when the vent pipes were placed in the middle or at the end of the pipeline. For lateral vent pipes close to the ignition source, their effective release of the not yet fully developed premixed flame allowed the heat absorption, wave absorption, and quenching performance of the installed metal wire mesh in the pipeline to fully exert their effects on the slow-spreading premixed flame. Furthermore, when a metal mesh was installed in the pipeline and the flame could not be extinguished, the flame penetrated the mesh structure, causing the flame front to become unstable and exhibit “irregular wrinkles”. That is, the flame front was no longer smooth, the wrinkles became more pronounced, and the degree of turbulence was enhanced.
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Stanford-McIntyre, Sarah. "The Saudi Arabia of Wind: Deregulation and the Rise of Wind Power in Texas". Revue d'Histoire de l'Énergie N° 7, n.º 1 (23 de junio de 2022): 1–20. http://dx.doi.org/10.3917/jehrhe.007.0001a.
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Cet article retrace l’histoire de l’essor de l’industrie éolienne au Texas à travers l’étude de la construction du parc de Roscoe en 2010, dans l’ouest de cet Etat des Etats-Unis. Il s’appuie sur une documentation provenant d’agences locales, étatiques et fédérales ainsi que sur des archives pour affirmer que l’essor de l’énergie éolienne au Texas au début du 21e siècle est le produit de grandes tendances liées à la déréglementation à l’œuvre à partir des années 1970. Cette dernière a eu deux effets. Premièrement, les décisions politiques des États et du gouvernement fédéral ont affaibli les anciens monopoles des services publics. Deuxièmement, les conséquences économiques et sociales de la déréglementation ont incité les habitants à s’intéresser au vent. À l’échelle nationale, la déréglementation et la mondialisation ont représenté un changement radical par rapport aux modes antérieurs de gestion des infrastructures par la loi. Au Texas, ce changement a accéléré le déclin des communautés rurales et fragilisé un ressort du nationalisme aigu texan. Cela a transformé les communautés rurales en défenseuses inattendues de l’énergie éolienne. La montée en puissance de l’énergie éolienne au Texas suggère que la tendance mondiale à la déréglementation et à la privatisation post-1970 a produit des effets variés sur les individus, les communautés et la cohésion de l’État.
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Kim, Yun Young y Chi Young Lee. "Effects of Fire Source Conditions on Vent Flow Velocity and Hot Gas Layer Characteristics in Two Rooms Connected by Vertical Opening". Fire Science and Engineering 37, n.º 4 (31 de agosto de 2023): 1–10. http://dx.doi.org/10.7731/kifse.a34b1647.
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In this study, the effects of fire source conditions on the vent flow velocity and hot gas layer characteristics in two rooms (ROOM-I and ROOM-II) connected by a vertical opening (VO-I) were investigated experimentally. In ROOM-II, the vertical opening (VO-II) connected to the outside was installed. The fire sources were located at the centers of ROOM-I and ROOM-II, and the heat release rates were 1.32, 3.32, and 5.21 kW. Regarding the vent flow velocity, when the fire source was located in ROOM-I, the outflow of the hot gas and inflow of cold air occurred in the upper and lower parts of VO-I and VO-II, respectively, which were the same as those of VO-II when the fire source was located in ROOM-II. However, when the fire source was located in ROOM-II, the hot gas in the upper part of VO-I flowed out to ROOM-I and flowed again into ROOM-II. Additionally, the hot gas layer thickness and temperature rise in the fire and adjacent rooms were compared. In the fire room, the case where the fire source was placed in ROOM-I showed a thicker hot gas layer and a higher hot gas layer temperature rise than the case where the fire source was placed in ROOM-II. In the adjacent room, the case where the fire source was placed in ROOM-I showed a thinner hot gas layer and a higher hot gas layer temperature rise than the case where the fire source was placed in ROOM-II. The dependence of the hot gas layer temperature rise on the heat release rate was higher than that of the hot gas layer thickness.
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Soubeyroux, Jean-Michel, Fabrice Dosnon, Jacques Richon, Michel Schneider y Pierre Lassegues. "Caractérisation à haute résolution spatiale des tempêtes historiques en métropole : Application à la tempête zeus du 6 Mars 2017". Climatologie 14 (2017): 96–106. http://dx.doi.org/10.4267/climatologie.1282.
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Une nouvelle méthode de spatialisation des rafales de vent à la résolution de 2,5 km sur la France a récemment été développée à partir des données anémométriques, des paramètres du relief et des analyses du modèle météorologique AROME pour caractériser les évènements de tempête à haute résolution spatio-temporelle. Différents indicateurs de sévérité ont été définis pour représenter les impacts des tempêtes aux différentes échelles nationale, régionale et départementale. Grâce à une reconstitution historique débutant en 1980, une nouvelle base de données de plus de 300 tempêtes a été constituée sur la France métropolitaine et mise à disposition sur internet. Ces diagnostics disponibles en temps réel ont été appliqués pour caractériser et qualifier la tempête Zeus du 6 mars 2017. Cette base de données originale permet aussi de préciser des diagnostics sur la variabilité et les effets du changement climatique sur l’aléa tempêtes et répondre aux différents besoins du secteur des assurances.
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Beck, F. E., J. P. Langlinais y A. T. Bourgoyne. "An Analysis of the Design Loads Placed on a Well by a Diverter System". Journal of Energy Resources Technology 120, n.º 1 (1 de marzo de 1998): 90–94. http://dx.doi.org/10.1115/1.2795017.
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Diverter systems, used as a means of well control while drilling surface hole, have a history of occasional failure. This paper addresses excessive back pressure, which can result in mechanical failure of surface equipment or foundation collapse. Flows at critical rates are shown both experimentally and theoretically to have a significant effect on back pressure. Critical flow is modeled by quantifying exit pressures and by including fluid acceleration pressure losses in back-pressure calculations. Experiments were then conducted in 1-in., 2-in., and 5-in. pipes to verify these mathematical models. A “systems analysis” approach was used for the diverter design, which allowed for consideration of wellbore and reservoir performance effects. This procedure allows the relationship of diverter vent line diameter, conductor depth, and drilling depth to be better identified, yielding improved design criteria.
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Barruffo, Alessandra, Laura Ciaralli, Giandomenico Ardizzone, Maria Cristina Gambi y Edoardo Casoli. "Ocean Acidification and Mollusc Settlement in Posidonia oceanica Meadows: Does the Seagrass Buffer Lower pH Effects at CO2 Vents?" Diversity 13, n.º 7 (8 de julio de 2021): 311. http://dx.doi.org/10.3390/d13070311.
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Ocean acidification has been broadly recognised to have effects on the structure and functioning of marine benthic communities. The selection of tolerant or vulnerable species can also occur during settlement phases, especially for calcifying organisms which are more vulnerable to low pH–high pCO2 conditions. Here, we use three natural CO2 vents (Castello Aragonese north and south sides, and Vullatura, Ischia, Italy) to assess the effect of a decrease of seawater pH on the settlement of Mollusca in Posidonia oceanica meadows, and to test the possible buffering effect provided by the seagrass. Artificial collectors were installed and collected after 33 days, during April–May 2019, in three different microhabitats within the meadow (canopy, bottom/rhizome level, and dead matte without plant cover), following a pH decreasing gradient from an extremely low pH zone (pH < 7.4), to ambient pH conditions (pH = 8.10). A total of 4659 specimens of Mollusca, belonging to 57 different taxa, were collected. The number of taxa was lower in low and extremely low pH conditions. Reduced mollusc assemblages were reported at the acidified stations, where few taxa accounted for a high number of individuals. Multivariate analyses revealed significant differences in mollusc assemblages among pH conditions, microhabitat, and the interaction of these two factors. Acanthocardia echinata, Alvania lineata, Alvania sp. juv, Eatonina fulgida, Hiatella arctica, Mytilys galloprovincialis, Musculus subpictus, Phorcus sp. juv, and Rissoa variabilis were the species mostly found in low and extremely low pH stations, and were all relatively robust to acidified conditions. Samples placed on the dead matte under acidified conditions at the Vullatura vent showed lower diversity and abundances if compared to canopy and bottom/rhizome samples, suggesting a possible buffering role of the Posidonia on mollusc settlement. Our study provides new evidence of shifts in marine benthic communities due to ocean acidification and evidence of how P. oceanica meadows could mitigate its effects on associated biota in light of future climate change.
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Xanthos, Jennifer B., Matthew Kofron, Qinghua Tao, Kyle Schaible, Christopher Wylie y Janet Heasman. "The roles of three signaling pathways in the formation and function of the Spemann Organizer". Development 129, n.º 17 (1 de septiembre de 2002): 4027–43. http://dx.doi.org/10.1242/dev.129.17.4027.
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Since the three main pathways (the Wnt, VegT and BMP pathways) involved in organizer and axis formation in the Xenopus embryo are now characterized, the challenge is to understand their interactions. Here three comparisons were made. Firstly, we made a systematic comparison of the expression of zygotic genes in sibling wild-type, VegT-depleted (VegT–), β-catenin-depleted (β-catenin–) and double depleted (VegT–/β-catenin–) embryos and placed early zygotic genes into specific groups. In the first group some organizer genes, including chordin, noggin and cerberus, required the activity of both the Wnt pathway and the VegT pathway to be expressed. A second group including Xnr1, 2, 4 and Xlim1 were initiated by the VegT pathway but their dorsoventral pattern and amount of their expression was regulated by the Wnt pathway. Secondly, we compared the roles of the Wnt and VegT pathways in producing dorsal signals. Explant co-culture experiments showed that the Wnt pathway did not cause the release of a dorsal signal from the vegetal mass independent from the VegT pathway. Finally we compared the extent to which inhibiting Smad 1 phosphorylation in one area of VegT–, or β-catenin– embryos would rescue organizer and axis formation. We found that BMP inhibition with cm-BMP7 mRNA had no rescuing effects on VegT– embryos, while cm-BMP7 and noggin mRNA caused a complete rescue of the trunk, but not of the anterior pattern in β-catenin– embryos.
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Mellier, Denis. "Figure(s) de sang : amours secrètes, troubles fratries et « miscégénation » dans The Searchers, The Unforgiven et The Missing". Cinémas 25, n.º 2-3 (23 de marzo de 2016): 33–53. http://dx.doi.org/10.7202/1035771ar.
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Sorti quatre ans après The Searchers (La prisonnière du désert, 1956), de John Ford, The Unforgiven (Le vent de la plaine, 1960), de John Huston, traite également des thèmes de la famille, des amours interdites et de la « miscégénation ». Au-delà des ressemblances attribuables à l’imaginaire des romans homonymes d’Alan LeMay que ces deux oeuvres adaptent, une circulation de motifs et d’arguments fonde un dialogue objectivable entre les deux films. Cet échange semble se poursuivre dans The Missing (Les disparues, 2002), de Ron Howard, où les mêmes éléments sont présents, mais déplacés et reformulés. Cet article examine la façon dont une figure, comprise comme un réseau de motifs et d’associations, permet une forme de reprise implicite conditionnant des effets de lecture complexes. Cette circulation figurale se distingue des formes de la réflexivité et de l’intertextualité ou du jeu avec les conventions d’un matériau générique. À l’intérieur de l’imaginaire du genre, le secret et l’implicite font émerger un sens jouant de libres associations, d’effets de mémoire et d’imagination. Il s’agit alors de s’interroger sur ce processus d’émergence dans le cadre d’une pensée de la généalogie des films qui ne saurait se limiter, sans pour autant les méconnaître, à leurs relations objectivées de reprises et d’influences.
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Trung Tran, Thien, Haraldur Bjarnason, Jennifer McDonald, Nils Oddvar Skaga, Damon E. Houghton, Brian Kim, Knut Stavem y Nils Einar Kløw. "Prophylactic placement of inferior vena cava filters and the risk of death or venous thromboembolism in severe trauma patients: a retrospective study comparing two hospitals with different approaches". Acta Radiologica Open 10, n.º 3 (marzo de 2021): 205846012199934. http://dx.doi.org/10.1177/2058460121999345.
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Background Prophylactic use of inferior vena cava filters to prevent pulmonary embolism in trauma is controversial. The practice varies between hospitals and countries, in part due to conflicting evidence and guidelines. Purpose To compare the effects of pulmonary embolism, deep venous thrombosis and mortality in two hospitals using prophylactic inferior vena cava filter placement or prophylactic anticoagulation alone. Material and Methods Patients presenting with severe trauma were recruited from two level-1 trauma centres between January 2008 and December 2013. Recruited patients from an US hospital having prophylactic inferior vena cava filter inserted were compared to a Scandinavian hospital using prophylactic anticoagulation alone. Inclusion criteria were age >15 years, Injury Severity Score >15 and survival >24 h after hospital admission. Patients with venous thromboembolism diagnosed prior to inferior vena cava filter placement were excluded. A Cox proportional hazard regression model was used with adjustment for immortal time bias and predictor variables. Results In total, 951 patients were reviewed, 282 from an US hospital having inferior vena cava filters placed and 669 from a Scandinavian hospital without inferior vena cava filters. The mean age was 45.9 vs. 47.4 years and the mean Injury Severity Score was 29.8 vs. 25.9, respectively. Inferior vena cava filter placement was not associated with the hazard of pulmonary embolism (Hazard ratio=0.43; 95% confidence interval (CI) 0.12, 1.45; P=0.17) or mortality (Hazard ratio=1.16; 95% CI 0.70, 1.95; P=0.56). However, an increased rate of deep venous thrombosis was observed with inferior vena cava filters in place (Hazard ratio=3.75; 95% CI 1.68, 8.36; P=0.001). Conclusion In severely injured trauma patients, prophylactic inferior vena cava filter placement was not associated with pulmonary embolism or mortality. However, inferior vena cava filters were associated with increased rate of deep venous thrombosis.
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GABILLET, Y., H. SCHROEDER y M. ROSEN. "UTILISATION DE LA MÉTHODE DE SOMMATION DE FAISCEAUX GAUSSIENS POUR LA MODÉLISATION DES EFFETS DU VENT SUR LA PROPAGATION ACOUSTIQUE AU-DESSUS DU SOL". Le Journal de Physique Colloques 51, n.º C3 (septiembre de 1990): C3–73—C3–82. http://dx.doi.org/10.1051/jphyscol:1990308.
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Mases, M., L. Buisson, W. Good y J. M. Vilaplana. "Etude de la répartition spatiale des effets du transport de neige par le vent ; premiers travaux réalisés à partir de mesures systématiques sur le terrain". La Houille Blanche, n.º 5-6 (agosto de 1995): 50–55. http://dx.doi.org/10.1051/lhb/1995045.
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Reid, Emily y Rachael Sikora. "Client perspectives on the support provided for the management of diabetes mellitus in dogs and cats". Veterinary Nurse 15, n.º 5 (2 de junio de 2024): 203–13. http://dx.doi.org/10.12968/vetn.2024.0017.
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Background: Literature suggests that owners of pets with diabetes mellitus are not adequately supported by veterinary professionals to manage their pet's condition. Quality of life assessments for diabetic pets in practice often focus on the animal's clinical signs and overlook owner feedback. Aims: To investigate client perspectives on how having a dog or cat with diabetes mellitus affects pet and owner quality of life, the challenges faced and management options available, and how support could be improved. Methods: A questionnaire was designed using the online tool ‘NoviSurvey’ and completed by UK-based owners. Results: Out of the 99 valid responses, 26% of participants disagreed that their veterinary practice supported them with their pet's diabetes mellitus. Results showed that diabetes mellitus is perceived to have a significant effect on quality of life of not only the pet with the disease but also the owner who is managing it. Conclusions: The effects of having a pet with diabetes mellitus on quality of life are being overlooked by the veterinary profession. Online support groups are an important platform for these owners to connect but should not be their primary source of advice because of a lack of veterinary support. Registered veterinary nurses are well placed to carry out regular quality of life assessments and provide evidence-based advice during clinics.
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Grindstaff, Regina R., Ryan J. Grindstaff y J. Thomas Cunningham. "Effects of right atrial distension on the activity of magnocellular neurons in the supraoptic nucleus". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 278, n.º 6 (1 de junio de 2000): R1605—R1615. http://dx.doi.org/10.1152/ajpregu.2000.278.6.r1605.
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A small balloon placed at the junction of the superior vena cava and right atrium was used to stimulate cardiac volume receptors in pentobarbital sodium-anesthetized male rats. Extracellular recordings were obtained from antidromically identified vasopressinergic and oxytocinergic neurosecretory cells of the supraoptic nucleus. Cells were considered sensitive to the stimulus if balloon inflation resulted in a 30% change in firing frequency. Balloon inflation that did not stretch the caval-atrial junction had no significant effect on vasopressin neurons ( n = 51, P > 0.05). Stretch of the caval-atrial junction decreased the firing activity in 64 of 83 putative vasopressin neurons ( P < 0.01 compared with control). Stretch of the caval-atrial junction influenced the firing activity of only 3 of 26 antidromically activated oxytocinergic neurons, an effect not statistically different from control ( P> 0.05). When bilateral vagotomy was performed while recording from vasopressin neurons ( n = 5), sensitivity to stretch of the caval-atrial junction was eliminated. Cardiac receptors located at the junction of the superior vena cava and right atrium may be important in regulating the activity of vasopressinergic but not oxytocinergic neurons of the supraoptic nucleus.
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Barnes, Stephen, Thorvaldur Thordarson, Robin E. T. Hill, Caroline S. Perring, Sarah E. Dowling y Belinda Godel. "Moinui Flow on Mauna Loa: transport and deposition of an olivine crystal cargo in a compound basaltic lava flow". Volcanica 7, n.º 1 (13 de mayo de 2024): 247–72. http://dx.doi.org/10.30909/vol.07.01.247272.
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The Moinui lava flow on the west flank of Mauna Loa, Hawai`i, is a 32-km-long pāhoehoe basalt flow, between 760 and 1500 years old, characterised by the presence of two generations of olivine: 2–5-mm-sized glomerocrystic clusters of equant polyhedral grains, and dendritic plates. Both generations are distributed throughout the flow field from the vent at 3400 m above sea level to the ocean. We mapped roadcut outcrops in detail to investigate the internal geometry and emplacement mechanisms of the flow, and sampled these outcrops to collect quantitative textural data on the two olivine populations in 2D and 3D, with a view to understanding emplacement processes in general, and the factors controlling the growth, transport, and deposition of phenocryst olivine in particular. Roadcut outcrops reveal complex geometries of interconnected tube-fed sheet lobes, with the main control being pre-existing topography: drained tubes with flanking sheet lobes were developed on the seaward slope of the volcano, whereas tumuli were developed on the flat coastal plain topography. The internal architecture of the flow field is consistent with current hypotheses of emplacement by breakout and inflation of flow lobes from tube-fed internal pathways. Concentrations of up to 30% olivine represent settling of the larger size-fraction of the transported load, with no evidence for superimposed effects of flow differentiation.Implied effective viscosities were around 1000 Pa s. The glomerocrystic population was inherited as pre-existing crystal clusters derived from a sub-volcanic chamber, rather than by synneusis (random collision and aggregation) post-eruption, whereas the plate population was probably generated by a burst of nucleation related to degassing and supercooling during the vent eruption. Other than this, there is no evidence for substantial growth of the transported olivines during flow.
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Li, Xiang, Runming Liu y Dalin He. "Malignant epithelioid angiomyolipoma invading inferior vena cava: Using a temporary vena cava filter to prevent tumor emboli during nephrectomy." Canadian Urological Association Journal 8, n.º 7-8 (11 de agosto de 2014): 564. http://dx.doi.org/10.5489/cuaj.1814.
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Angiomyolipoma (AML) is generally considered to be benign and malignant angiomyolipoma is rare. This paper presents an extremely rare case of epithelioid AML with tumour thrombus invading inferior vena cava (IVC). We present the case of a 36-year-old woman with epithelioid AML with tumour thrombus invading inferior vena cava who underwent radical nephrectomy and IVC thrombectomy. As an adjunctive procedure, a temporary IVC filter was placed in suprarenal position before operation. One week after surgery, the temporary IVC filter was retrieved by femoral approach. Three months postoperatively, a computed tomography scan and abdominal ultrasonogaphy showed no evidence of thrombus in IVC or renal vein and no sign of tumour recurrence. Epithelioid AML is extremely rare and can be malignant, with invasion of the IVC or renal vein. Implanting temporary filter can prevent fatal pulmonary complication and avoid potential the side effects of permanent filter.
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Ishizuka, M. "The effects of the outlet area and the location of the main power supply unit on the cooling capability through naturally air-cooled electronic equipment casings". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 212, n.º 5 (1 de agosto de 1998): 381–83. http://dx.doi.org/10.1243/0957650981536943.
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This paper describes a practical thermal design approach to natural air-cooled electronic equipment casings. A set of simplified equations for the thermal design of natural air-cooled electronic equipment casings has been proposed. The proposed set of equations satisfied the demand of practical air-cooling systems, since it takes account of factors such as the stack effect, the air flow resistance and the heat transfer due to natural convection. The effects of the outlet area and the location of the main power supply unit on the natural cooling capability of electronic equipment casings were studied using a set of equations. The results have shown that a uniform temperature distribution could be achieved when the main power supply unit was placed at the bottom of the casing. It has also been suggested that the value of the heat removed from the casing surface could be more significant than that from the outlet vent in the thermal design of natural air-cooled electronic equipment casings.
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Takata, M. y J. L. Robotham. "Effects of inspiratory diaphragmatic descent on inferior vena caval venous return". Journal of Applied Physiology 72, n.º 2 (1 de febrero de 1992): 597–607. http://dx.doi.org/10.1152/jappl.1992.72.2.597.
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To explain the contradictory results in the literature regarding the effects of inspiratory diaphragmatic descent on inferior vena caval (IVC) venous return, we evaluated changes in total IVC flow as well as regional splanchnic and nonsplanchnic IVC flows by use of ultrasound flow probes placed around the thoracic and subhepatic abdominal IVC during phrenic nerve stimulation (PNS) in anesthetized open-chest dogs. With the abdomen closed (n = 6), PNS under hypervolemic conditions increased the total IVC flow by enhancing the splanchnic IVC flow, with a transient decrease in the nonsplanchnic IVC flow (P less than 0.05). Under hypovolemic conditions, PNS initially increased the total IVC flow but later decreased the total IVC flow by reducing the nonsplanchnic IVC flow, associated with a venous pressure gradient in the IVC across the diaphragm (P less than 0.05), consistent with development of a vascular waterfall. With the abdomen widely open, the mobile abdominal contents eviscerated, and the subhepatic IVC occluded (n = 5), PNS increased the splanchnic IVC flow associated only with an increase in focal contact pressure over the liver without any increase in general abdominal pressure (Pab) (P less than 0.05). These results suggest that our previously proposed concept of abdominal vascular zone conditions (J. Appl. Physiol. 69: 1961–1972, 1990) is useful as a global approximation to understand the effects of respiratory-induced changes in Pab's on the total and regional IVC venous return. Nonhomogeneous distribution of Pab's during diaphragmatic descent may need to be considered to explain all aspects of the behavior of the intact IVC system.
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Houfflin-Debarge, V., A. Delelis, S. Jaillard, B. Larrue, P. Deruelle, A. S. Ducloy, F. Puech y L. Storme. "Effects of nociceptive stimuli on the pulmonary circulation in the ovine fetus". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 288, n.º 2 (febrero de 2005): R547—R553. http://dx.doi.org/10.1152/ajpregu.00433.2004.
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The fetus is able to exhibit a stress response to painful events, and stress hormones have been shown to modulate pulmonary vascular tone. At birth, the increased level of stress hormones plays a significant role in the adaptation to postnatal life. We therefore hypothesized that pain may alter pulmonary circulation in the perinatal period. The hemodynamic response to subcutaneous injection of formalin, which is used in experimental studies as nociceptive stimulus, was evaluated in chronically prepared, fetal lambs. Fetal lambs were operated on at 128 days gestation. Catheters were placed into the ascending aorta, superior vena cava, and main pulmonary artery. An ultrasonic flow transducer was placed around the left pulmonary artery. Three subcutaneous catheters were placed in the lambs' limb. The hemodynamic responses to subcutaneous injection of formalin, to formalin after fetal analgesia by sufentanil, and to sufentanil alone were recorded. Cortisol and catecholamine concentrations were also measured. Pulmonary vascular resistances (PVR) increased by 42% ( P < 0.0001) after formalin injection. Cortisol increased by 54% ( P = 0.05). During sufentanil infusion, PVR did not change significantly after formalin. Cortisol increased by 56% ( P < 0.05). PVR did not change during sufentanil infusion. Norepinephrine levels did not change during any of the protocols. Our results indicate that nociceptive stimuli may increase the pulmonary vascular tone. This response is not mediated by an increase in circulating catecholamine levels. Analgesia prevents this effect. We speculate that this pulmonary vascular response to nociceptive stimulation may explain some hypoxemic events observed in newborn infants during painful intensive care procedures.
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Brun, Clément. "Dois-je aussi me mettre nu ?" Géographie et cultures 120-121 (2021): 205–24. http://dx.doi.org/10.4000/11tj5.
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Depuis 2002, il est possible de se baigner dans le port de Copenhague. Plébiscitée par les habitants, la baignade nous donne à voir un rapport nouveau entre eux et la ville, les espaces au bord de l’eau leur permettant de se relâcher et d’exposer leurs corps au soleil, au sol, au vent et à l’altérité. Se baigner dans la ville remplit notamment une fonction d’identification à une même culture nordique qui s’exprime à travers un rapport à la nudité décomplexé. Ces questions sont l’objet de notre travail de thèse en cours. Dans cet article, nous posons la question épistémologique de mon rapport personnel à l’enquête. À partir de travaux questionnant la subjectivité de l’enquêteur lorsqu’il doit participer à l’activité qu’il étudie, nous interrogeons les biais méthodologiques pouvant naître de la proximité avec son terrain. Qu’en est-il lorsqu’on étudie la baignade urbaine dans un pays étranger ? Est-on obligé de se baigner lorsqu’on a la baignade comme objet d’étude ? En étant observateur de situations où les corps sont dénudés et en participant nous-même à ces expériences d’altérité dénudée, cette enquête pousse-t-elle au voyeurisme ? Cet article se concentre sur les choix méthodologiques pour mener à bien une étude sur les pratiques de baignade urbaine. À partir de ce retour d’expérience, ce travail propose un questionnement personnel sur les effets d’enquête lorsque l’enquêteur est lié avec le terrain par filiation. Nous discuterons de l’importance de la participation aux activités durant l’observation, pour permettre la production de données expérientielles utiles à l’enquêteur, mais aussi pour rentrer plus aisément en contact avec les enquêtés dans un terrain situé à l’étranger.
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Kemadjou Mbakemi, Déric Larey, Joseph Youta Happi y Roger Ngoufo. "Bosquets anthropiques et afforestation des savanes au confluent du Mbam et de la Sanaga, Centre Cameroun". Physio-Géo Volume 20 (2024): 151–69. http://dx.doi.org/10.4000/12jta.
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La mosaïque de peuplements végétaux du Centre Cameroun fait cohabiter, sur près de 100 000 km2, des forêts denses humides semi-décidues et des savanes herbeuses et arbustives. Dans la partie méridionale de ce domaine, au confluent de la rivière Mbam et du fleuve Sanaga, on assiste à une dynamique à l'avantage des forêts du fait de facteurs à la fois naturels et humains. Si les facteurs naturels ont déjà été bien documentés, les effets des activités humaines restent à être mieux étudiées. La présente contribution a pour objectif de comprendre comment les actions des sociétés paysannes participent à la construction des paysages et particulièrement à la création de forêts au détriment des savanes. Il s'agit de définir les étapes et les mécanismes de cette conquête forestière qui débute par l'apparition de bosquets et d'îlots de forêt en savane. La méthodologie fait appel à des relevés botaniques, ainsi qu'à des enquêtes auprès de la population. D'abord sécuritaires, les préoccupations à l'origine de cette dynamique paysagère sont ensuite devenues économiques, puis aujourd'hui foncières. Le rôle assigné à l'arbre en savane a évolué dans le temps. D'abord planté et utilisé autour des villages comme haie défensive au XIXème siècle, dans un contexte de guerres tribales, l'arbre a ensuite servi comme pare-feu et brise-vent autour des habitations et comme support à l'agroforesterie, en fournissant par exemple de l'ombrage pour la culture du cacao. Il est désormais planté aussi pour marquer l'appropriation d'un espace. La combinaison de ces facteurs entraîne une afforestation de la savane à travers la multiplication des bosquets entourant les cases, des bosquets post-culturaux et des bosquets agroforestiers.
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Kamenos, N. A., G. Perna, M. C. Gambi, F. Micheli y K. J. Kroeker. "Coralline algae in a naturally acidified ecosystem persist by maintaining control of skeletal mineralogy and size". Proceedings of the Royal Society B: Biological Sciences 283, n.º 1840 (12 de octubre de 2016): 20161159. http://dx.doi.org/10.1098/rspb.2016.1159.
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To understand the effects of ocean acidification (OA) on marine calcifiers, the trade-offs among different sublethal responses within individual species and the emergent effects of these trade-offs must be determined in an ecosystem setting. Crustose coralline algae (CCA) provide a model to test the ecological consequences of such sublethal effects as they are important in ecosystem functioning, service provision, carbon cycling and use dissolved inorganic carbon to calcify and photosynthesize. Settlement tiles were placed in ambient pH, low pH and extremely low pH conditions for 14 months at a natural CO 2 vent. The size, magnesium (Mg) content and molecular-scale skeletal disorder of CCA patches were assessed at 3.5, 6.5 and 14 months from tile deployment. Despite reductions in their abundance in low pH, the largest CCA from ambient and low pH zones were of similar sizes and had similar Mg content and skeletal disorder. This suggests that the most resilient CCA in low pH did not trade-off skeletal structure to maintain growth. CCA that settled in the extremely low pH, however, were significantly smaller and exhibited altered skeletal mineralogy (high Mg calcite to gypsum (hydrated calcium sulfate)), although at present it is unclear if these mineralogical changes offered any fitness benefits in extreme low pH. This field assessment of biological effects of OA provides endpoint information needed to generate an ecosystem relevant understanding of calcifying system persistence.
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Thirkateh, Prahasit, Ahsun Riaz, Matthew C. Tate, Seth Stein y Scott A. Resnick. "Combined cut down and endovascular retrieval of orphaned ventriculoatrial shunt with stenting of chronic superior vena cava occlusion". Pediatric Radiology 51, n.º 8 (12 de enero de 2021): 1531–34. http://dx.doi.org/10.1007/s00247-020-04943-3.
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AbstractRevascularization of the superior vena cava (SVC) in the context of symptomatic luminal obstruction is a therapeutic intervention performed for SVC syndrome of benign or malignant etiology. Venous occlusion can preclude future access and cause symptoms ranging from mild chest discomfort to the more serious effects of SVC syndrome. This case report demonstrates the treatment of a novel case of SVC syndrome arising from a previously placed SVC stent. An intravascular, extraluminal orphaned ventriculoatrial shunt was used to go through the SVC but around the existing lumen-limiting stent to place a new larger stent for revascularization. This case highlights the need for an innovative approach for complex foreign body retrieval and treatment of chronic SVC occlusion.
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Policastro, Piero y Luca Mesin. "Processing Ultrasound Scans of the Inferior Vena Cava: Techniques and Applications". Bioengineering 10, n.º 9 (12 de septiembre de 2023): 1076. http://dx.doi.org/10.3390/bioengineering10091076.
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The inferior vena cava (IVC) is the largest vein in the body. It returns deoxygenated blood to the heart from the tissues placed under the diaphragm. The size and dynamics of the IVC depend on the blood volume and right atrial pressure, which are important indicators of a patient’s hydration and reflect possible pathological conditions. Ultrasound (US) assessment of the IVC is a promising technique for evaluating these conditions, because it is fast, non-invasive, inexpensive, and without side effects. However, the standard M-mode approach for measuring IVC diameter is prone to errors due to the vein movements during respiration. B-mode US produces two-dimensional images that better capture the IVC shape and size. In this review, we discuss the pros and cons of current IVC segmentation techniques for B-mode longitudinal and transverse views. We also explored several scenarios where automated IVC segmentation could improve medical diagnosis and prognosis.
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Cantat, Olivier y Alexandre Follin. "Les singularités thermiques d’un espace périurbain dans une agglomération de dimension moyenne : le cas de Caen durant l’hiver 2018/2019". Climatologie 17 (2020): 3. http://dx.doi.org/10.1051/climat/202017003.
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L’analyse comparative des données météorologiques de la station rurale de Carpiquet avec une station expérimentale en périphérie de la ville de Caen a permis de montrer la présence en hiver d’un léger îlot de chaleur péri-urbain (ICPU) (moyenne de +0,4°C). Il est caractérisé par un maximum d’intensité en fin d’après-midi et début de soirée (+0,8°C) et des écarts faibles le reste du temps. Derrière cette image moyenne, une analyse du continuum temporel au pas de temps journalier puis horaire a mis en exergue des comportements différenciés selon les types de temps. Le caractère le plus original des résultats est la présence certes rare, mais significative en termes d’intensité, d’un îlot de fraîcheur péri-urbain (IFPU). Il se forme de nuit par temps clair et calme et se prolonge dans la matinée, jusqu’à présenter un maximum d’intensité vers 9 h UTC. Cette inversion par rapport au schéma classique de fonctionnement des îlots de chaleur urbain (ICU) s’explique par un mode d’occupation du sol favorable à la formation d’une poche froide par rayonnement nocturne, favorisée par l’absence totale de vent (effet de barrage du bâti et de la végétation) et par la faible densité urbaine, alors que sur la campagne ces mécanismes de refroidissement sont atténués par la persistance d’un léger flux. Cet IFPU résiste et s’intensifie en début de matinée, jusqu’à temps que le soleil et la turbulence de l’air ne viennent échauffer et disperser cette pellicule d’air froid plus dense. Ici, les conditions stationnelles semblent donc primer sur les effets purement urbains car l’agglomération de Caen ne présente pas une masse suffisante pour créer une « bulle chaude » jusque dans ses quartiers périphériques quand un type de temps radiatif s’impose.
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Takpa, O’Neil G. M. M., G. Pierre Tovihoudji, Nouroudine Ollabodé, P. B. Irénikatché Akponikpè y Jacob A. Yabi. "Perception des producteurs des changements climatiques et stratégies d’adaptation dans les systèmes de culture à base de maïs (Zea mays) au Nord-Bénin". Annales de l’Université de Parakou - Série Sciences Naturelles et Agronomie 12, n.º 1 (30 de junio de 2022): 1–14. http://dx.doi.org/10.56109/aup-sna.v12i1.7.
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En Afrique subsaharienne, le développement durable est menacé par le changement climatique par ces effets néfastes sur l'environnement, la sécurité alimentaire, la santé, etc. en effet, les producteurs du Nord-Bénin sont de plus en plus confrontés au besoin d’adapter leurs systèmes de cultures aux circonstances changeantes du climat. Cette étude analyse la décision d’adaptation des producteurs et leur perception du changement climatique. Les données sont collectées auprès de 262 producteurs de maïs échantillonnés de façon aléatoire dans trois zones agro écologiques du nord Bénin à travers une enquête socioéconomique. Le modèle Probit de Heckman est estimé pour identifier les facteurs déterminants la perception et l’adaptation des producteurs aux variabilités climatiques. Cette étude montre que les producteurs s’adaptent au changement climatique à condition qu’ils le perçoivent à travers des précipitations, de la température, du vent et de la disparition dans le paysage agroécologique. En réponse à ces changements, les stratégies adoptées sont entre autres : modification des dates de semis (91,4%) ; diversification des cultures (88%) ; autres adaptations comme les prières et rituels traditionnels (70%) ; stratégies de fertilisation dont la microdose (63,8%) ; adoption d’une nouvelle variété (43,5%) ; abandon ou diminution des spéculations (34,7%). Le modèle utilisé révèle que les producteurs s’adaptent au changement climatique à condition qu’ils le perçoivent. Le nombre d’actifs agricoles et l’association maïs-légumineuse influencent la perception du producteur tandis que le niveau d’éducation primaire, le droit de propriété sur la terre et l’appartenance du producteur à une organisation ont des incidences sur la décision d’adaptation du producteur au changement climatique. Par conséquent, les politiques gouvernementales qui visent à promouvoir des stratégies d'adaptation au changement climatique doivent tenir compte de ces facteurs pour améliorer les chances des mesures d’adoption des producteurs.
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Gavazza, M., M. Marmunti, M. Compagnoni y A. Palacios. "Antioxidant effect of lutein protects against oxidative damage to porcine spermatozoa". Revista Veterinaria 30, n.º 1 (8 de agosto de 2019): 7. http://dx.doi.org/10.30972/vet.3013876.
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<p>Boar sperm is especially susceptible to peroxidative damage generated by reactive oxygen species (ROS). Chemiluminescence was initiated by incubating porcine semen in an in vitro ascorbate-Fe++ system, a technique that allows the evaluation of oxidative stress in these cells. Lutein is known for its antioxidant effects, chemically it is a dihydric derivative of α-carotene and belongs to the group of xanthophylls. The main objective of this study was to investigate the antioxidant effect of lutein on boar spermatozoa. The effect of lutein was analyzed by two methods: 1) by adding lutein: the sperm samples were placed in an in vitro ascorbate-Fe++ system, during 120 min at 37°C adding increasing amounts of lutein (50, 150 and 250 μg) per mg of protein and 2) by incubation with lutein in an in vitro ascorbate-Fe+2 system, for 120 min at 37°C, using spermatozoa obtained from porcine semen samples previously incubated with lutein (0.15 and 0.25 mg/ml) during 24 h at 15°C. In both methods a control group (without lutein) was used. Peroxidation was measured by chemiluminescence using a liquid scintillation counter, the light emission being quantified in cpm (counts per minute). Analyzing the effect of lutein by the two methods, it was observed that the total amount of cpm/mg of protein originated by chemiluminescence was lower in samples obtained from the lutein group than in the control group (without lutein). Total chemiluminescence (cpm total) was lower in samples obtained from the lutein group than in the control group (without lutein), with a significance of p<0.005. Percent inhibition of peroxidation was not concentration dependent. These results would demonstrate that lutein could act as an antioxidant that would protect the membranes of the sperm from oxidative damage.</p>
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Reiner, Martin F., Simona Stivala, Kimberly Martinod, Giovanni G. Camici, Thomas F. Lüscher, Denisa D. Wagner y Juerg H. Beer. "Dietary Alpha-Linolenic Acid Does Not Protect From Venous Thrombosis In The Vena Cava Stenosis Model". Blood 122, n.º 21 (15 de noviembre de 2013): 3621. http://dx.doi.org/10.1182/blood.v122.21.3621.3621.
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Abstract Background Deep vein thrombosis (DVT) and pulmonary embolism (PE) are major causes of cardiovascular morbidity and mortality. Omega-3 fatty acids (n-3 FA) are well known for their beneficial effects on primary and secondary prevention of cardiovascular disease (CVD). We and others have previously reported that n-3 FA, particularly the plant-derived alpha-linolenic acid (ALA), inhibits atherosclerosis, reduces arterial thrombosis and decreases platelet activation in mice fed an n-3-enriched diet by antiinflammatory, antiplatelet and anticoagulant mechanisms. In this study we investigated the effects of ALA on the development of DVT in the vena cava stenosis model in mice. Hypothesis Because platelet activation and inflammatory processes may play a relevant role in venous thromboembolism, we hypothesized that ALA prevents the development of venous thrombosis in mice undergoing vena cava stenosis due to its antiplatelet, anticoagulant and antiinflammatory properties. Methods 12 to 14 weeks old C57/BL6 mice underwent 4 weeks of high- (7.3g%; hiALA) or low-ALA (0.03g%; loALA) treatment (n=11 per group) before they were exposed to vena cava stenosis. Rodents were anaesthetized, the inferior vena cava (IVC) was exposed and a ligature was placed proximal to the left renal vein in order to narrow the IVC and to provoke a reduction in blood flow and thereby induce thrombus formation. Mice were examined 48 hours after initial surgery; percentage of mice with thrombus formation and thrombus length were determined. Additionally, we performed blood count analysis and determined plasma glycocalicin index (ug/ml/250 000 platelets), the extramembranous portion of GPIbalpha, as a marker for platelet turnover and shedding of the platelet receptor for von Willebrand factor (vWF). Results Contrary to our hypothesis, treatment with ALA did neither significantly reduce the incidence (hiALA, 55 % vs loALA, 64 %; n=11 per group, p=ns) nor size of venous thrombosis (hiALA, 2.4 mm vs loALA, 2.3 mm; n=11 per group, p=ns). Glycocalicin index was comparable in both groups (hiALA, 15.0±8.1 ug/ml/250 000 platelets vs loALA, 11.1±4.5 ug/ml/250 000 platelets; n=8 per group, p=ns), indicating no difference in platelet consumption. Interestingly, we observed an increased leukocyte count and a reduced platelet count in hiALA-treated mice after 48 hours of venous thrombosis, a difference that was not observed in sham operated mice. Conclusions Dietary ALA did not protect from DVT in the mouse model of vena cava stenosis chosen. Despite its protective properties in arterial thrombosis, ALA seems to be ineffective in the pathogenesis of the stenosis-induced venous thrombosis, possibly because the pathways of platelet activation and inflammation, modified by ALA, are of lower penetrance. The findings of increased leukocyte count and decreased platelet count after 48 h of VT warrant further investigation. Disclosures: No relevant conflicts of interest to declare.
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Dagenais, M., G. Pomier-Layrargues, B. Rocheleau, L. Giroux y P. M. Huet. "Systemic and splanchnic haemodynamic effects of pentifylline in rats with portal hypertension". Clinical Science 83, n.º 1 (1 de julio de 1992): 41–45. http://dx.doi.org/10.1042/cs0830041.
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1. The systemic and splanchnic haemodynamic effects of pentifylline (40 mg/kg body weight intravenously) were assessed in rats with portal hypertension associated either with CCl4-induced cirrhosis (n= 13) or portal vein ligation (n=13). 2. Heparinized catheters were placed into the portal vein, inferior vena cava, aorta and left ventricle with exits from the neck. Haemodynamic studies were performed 4 h after consciousness was regained. Cardiac output and regional blood flows were measured using radiolabelled microspheres and the reference sample method in seven rats in each group; portal-systemic shunting was measured using microsphere injection in the ileo-colic vein in six rats in each group. 3. Forty-five minutes after injection, pentifylline had no effect on mean arterial pressure, cardiac output, peripheral resistance, portal venous flow, hepatic artery flow or portal-systemic shunting in either group of rats with portal hypertension. The drug lowered portal pressure (−18%) in cirrhotic rats, but not in portal-vein-ligated rats. 4. These data demonstrate that pentifylline lowers portal pressure in cirrhotic rats without affecting portal venous flow and portal-systemic shunting; this effect is possibly mediated by changes in intrahepatic resistance related to the effects of pentifylline on blood viscosity and/or on intrahepatic vasomotor tone.
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Yonzoua, C. C. Fandjio, U. J. M. Pettang Nana, M. B. Manjiaa y C. Pettanga. "Mesure de la vulnérabilité des milieux urbains au Cameroun face au changement climatique". Journal of the Cameroon Academy of Sciences 17, n.º 2 (12 de enero de 2022): 115–29. http://dx.doi.org/10.4314/jcas.v17i2.3.
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Les différentes catastrophes survenues en milieu urbain au Cameroun récemment, mettent en exergue les désormais dangers permanents qui pèsent sur les habitants. On note une augmentation des extrêmes : de hautes températures, des perturbations des régimes pluvieux et la récurrence des vents violents. Certains de ces effets sont amplifiés par la géographie contraignante de plusieurs villes et par l’influence anthropique sur l’environnement. En effet, d’une part les sites de plusieurs villes camerounaises ont soit des reliefs accidentés qui favorisent l’érosion des terrains, soit des configurations planes qui limitent l’évacuation gravitaire de l’eau de ruissellement. D’autre part, la croissance urbaine rapide et la prolifération des bidonvilles qui couvrent près de 65 à 70% de la superficie urbaine, usent plus rapidement les ouvrages et infrastructures d’assainissement urbaines lorsqu’ils existent dus à l’imperméabilisation accélérée et continue du sol urbain ainsi qu’à la mauvaise gestion des déchets. L’urgence de trouver des solutions durables à ce phénomène est désormais sans équivoque. Elle nécessite un encadrement normatif inclusif plus performant que celui actuellement en vigueur, qui amène le pays vers la résilience.
The disasters that’ve occurred recently in urban areas in Cameroon, highlight the permanent dangers weighing on the inhabitants. There is an increase in extremes climate parameters: high temperatures, rainfall disturbances and the recurrence of gales. Some of these effects are amplified by both the constraining relief of several cities and human influence on the environment. In fact, on the one hand, the sites of several Cameroonian cities either have rugged reliefs that promote land erosion, or flat configurations that limit the gravity discharge of runoff water. On the other hand, the rapid urban growth and the proliferation of slums which cover nearly 65 to 70% of the urban area, wear out more quickly the works and urban sanitation infrastructures when they exist due to the accelerated and continuous waterproofing soil in addition to the poor waste management. The urgency to find lasting solutions to this phenomenon is now unequivocal. It requires an inclusive normative framework that is more effective than that currently in force, which brings the country towards resilience.
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Toy, Cynthia, Grant Stimes, Megan Moore, Poyyapakkam Srivaths y Ayse Akcan Arikan. "Cefepime Dosing in a Critically Ill Neonate Receiving Continuous Renal Replacement Therapy With the Cardio-Renal Pediatric Dialysis Emergency Machine (CARPEDIEM)". Journal of Pediatric Pharmacology and Therapeutics 28, n.º 2 (1 de abril de 2023): 167–71. http://dx.doi.org/10.5863/1551-6776-28.2.167.
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We report on a former 27-week gestational age infant who was placed on the Cardio-Renal Pediatric Dialysis Emergency Machine (CARPEDIEM) at 4 months post-menstrual age while receiving cefepime treatment for an Enterobacter cloacae bacteremia and persistent peritonitis secondary to an infected peritoneal dialysis catheter. Using therapeutic drug monitoring while assessing the clearance of cefepime on continuous renal replacement therapy (CRRT), we were able to successfully treat this patient's infection while also minimizing the risk of side effects from this medication. Current literature supports dosing in adult patients on all modalities of CRRT with effluent flow rates of 20 to 25 mL/kg/hr; however, pharmacokinetic data on cefepime dosing in pediatric CRRT are scant. This case report describes the successful dosing strategy used for this patient while on various rates of continuous veno-venous hemodialysis with CARPEDIEM. Therapeutic drug monitoring of cefepime should be considered in critically ill pediatric patients on CARPEDIEM receiving CRRT.
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Djemna, Esther Pouomogne, Yolande Madeleine Pouomogne Guiawa, Paul Zango, Thomas Efole Ewoukem, Minette Tomedi Eyango y Victor Pouomogne. "Effets de la fertilisation par compostage ou par intégration directe, et de l’âge des porcs, sur les performances zootechniques du tilapia <i>Oreochromis niloticus</i> en polyculture d’étang". International Journal of Biological and Chemical Sciences 18, n.º 1 (9 de mayo de 2024): 129–40. http://dx.doi.org/10.4314/ijbcs.v18i1.11.
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En contribution à l'optimisation des systèmes d'élevage pour une production piscicole durable accrue en milieu paysan subsarien, deux essais consécutifs utilisant des duplicats de juvéniles de tilapia Oreochromis niloticus (poids moyens initiaux 81+1,1g ; puis 25+1,2g) en polyculture avec la carpe commune et le silure africain (densités totales respectives 1+0,2+1,2 ind/m², puis 1,2+0,8+0) ont été menés dans 4 bassins en terre (superficie en eau, 25 m²) de la ferme FRAPAIK-Moyo dans les Hautes Terres de l'Ouest du Cameroun. Le premier essai testait les effets de la fertilisation à la compostière intra-étang et l'intégration porc-poisson (porcelets sevrés de 20 kg en porcherie surplombant les eaux de l’étang). Le deuxième essai portait sur l’effet fertilisant en intégration porc-poisson de jeunes porcs de 40 kg comparé à des porcs adultes de 75 kg. La qualité physico-chimique de l'eau, la survie, la croissance des poissons, et plus particulièrement pour le deuxième essai, la carcasse des tilapias, ont été analysés. Des pêches de contrôle ont été effectuées toutes les 3 semaines. Les investigations ont duré respectivement 56 et 84 jours. Aucune différence significative (p˃0,05) n'a été observée sur la qualité de l'eau (T° 21,0+0,1°C ; pH 6,8+0,5 ; oxygène dissous 3,5+2,5 mg/l) et les taux de survie (en moyenne de 89,5+2,0%). La fertilisation via la compostière a permis une meilleure croissance de la carpe commune (0,77 ± 0,12 g/j > 0,246 ± 0,03) et du tilapia (0,16 ± 0,016 > 0,13 ± 0,036), contrairement au silure (0,73 ± 0,10 ˂ 0,9 ± 0,09) qui a mieux valorisé les fèces de porc. Dans le deuxième essai, le TCS du tilapia variait de manière non significative (p˃0,05) entre 1,55 + 1,14 %/j (jeunes porc) et 1,52 + 0,83 %/j (adulte) ; par contre, le zooplancton s'est révélé significativement (p˂0,05) plus abondant dans l'intégration des jeunes par rapport aux porcs adultes (4872 rotifères + cladocères + copépodes/ml, contre 701). Les teneurs en protéines, lipides et cendres corporelles du tilapia variaient sans différence significative dans les plages habituelles. En définitive, l’utilisation de la compostière devrait être encouragée, et le fumier de jeunes porcs préféré à celui de porcs adultes, pour la polyculture du tilapia du Nil avec la carpe commune. English title: Impacts of fertilizing with intra-pond composter or direct integrated fertilization, and the age of pigs on zootechnical performances of tilapia Oreochromis niloticus, in pond polyculture In view of better improving integrated fish culture practices for sustainable increased production in real on-farm sub-saharan conditions, two consecutive tests with duplicate batches of juvenile tilapia Oreochromis niloticus (initial average weights 81 + 1.1g; then 25 + 1.2 g), common carp and African catfish cultured altogether (total densities respectively 1+1.2+0.2 ind / m², then 1.2+0.8+0) were conducted in 4 earthen basins (25 m² area) at the FRAPAIK-Moyo fish farm, Western Cameroon Highlands. The first trial compared fertilizing with intrapond composter and pig cum fish integration. The second dealt with integrated fertilization using 40 kg young pigs, versus 75 kg adults. The parameters measured included water quality, survival, fish growth, and specifically for the second trial, tilapia carcass. Intermediate samplings were carried out at 3 weeks interval. The experimental periods lasted 56 and 84 days respectively. Fertilization via the composter led to the better growth of common carp (0.77 ± 0.12 g/d> 0,246 ± 0.03) and tilapia (0.16 ± 0.016 > 0.13 ± 0.036), differently to catfish which better valued pig faeces (0.73 ± 0.10 ≤0.9 ± 0.088). In test 2, zooplankton was found to be significantly more abundant (4872 rotifers + cladoceras + copepods / ml, against 701). Compost crib should then be encouraged in Nile tilapiacommon carp polyculture, and piglets manure preferred to adults in tilapia fattening.
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Chatfield, B. A., I. F. McMurtry, S. L. Hall y S. H. Abman. "Hemodynamic effects of endothelin-1 on ovine fetal pulmonary circulation". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 261, n.º 1 (1 de julio de 1991): R182—R187. http://dx.doi.org/10.1152/ajpregu.1991.261.1.r182.
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To determine the hemodynamic effects of endothelin-1 (ET-1) in the fetal pulmonary circulation, we studied pulmonary vascular responses to brief and prolonged intrapulmonary infusions of the peptide in nine chronically prepared late-gestation fetal sheep. Left pulmonary artery (LPA) blood flow was measured with an electromagnetic flow transducer, and a catheter placed in the LPA allowed ET-1 infusion directly into the left lung. Brief (10-min) infusions of ET-1 (12.5-100 ng/min) increased flow up to 212% of baseline without changing pulmonary artery pressure. With prolonged (120-min) infusion of ET-1 (50 ng/min), flow increased from 69 +/- 8 to 164 +/- 23 ml/min at 10 min (P less than 0.05) but then declined and was not different from baseline at 120 min. The gradient between mean pulmonary artery and aortic pressures did not change, suggesting no constriction of the ductus arteriosus. Systemic (vena caval) infusion of ET-1 (100 ng/min for 30 min) caused systemic and pulmonary hypertension, as mean pulmonary artery pressure increased from 43 +/- 1 to 51 +/- 2 mmHg (P less than 0.05) and remained elevated for 30 min after cessation of the ET-1 infusion. We conclude that intrapulmonary ET-1 is a potent fetal pulmonary vasodilator, but its dilator effect is transient during prolonged infusion. In contrast, systemic infusion causes sustained hypertension, suggesting differential effects of ET-1 on the pulmonary and systemic circulations. These findings demonstrate marked vasoactivity of ET-1 in the fetus, suggesting a potential role in the normal or abnormal transitional circulation.
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Piacentini, M. F., R. Clinckers, R. Meeusen, S. Sarre, G. Ebinger y Y. Michotte. "Effect of bupropion on hippocampal neurotransmitters and on peripheral hormonal concentrations in the rat". Journal of Applied Physiology 95, n.º 2 (agosto de 2003): 652–56. http://dx.doi.org/10.1152/japplphysiol.01058.2002.
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The purpose of the present study was to administer an acute dose of the dual dopamine norepinephrine reuptake blocker bupropion in freely moving rats and to monitor the extracellular neurotransmitter concentrations in the hippocampus via in vivo microdialysis and the peripheral hormonal concentrations via catheterization. A microdialysis probe was inserted in the hippocampus, and samples for serotonin, dopamine, and norepinephrine were collected every 20 min before and after the injection of 17 mg/kg of bupropion, for a total sampling time of 180 min. A catheter was placed in the vena femoralis of the second group of rats, and blood samples were collected before and after bupropion injection for quantification of growth hormone, prolactin, corticosterone, adrenocorticotropin hormone, and β-endorphins. All neurotransmitter levels (dopamine, norepinephrine, and serotonin) significantly increased after bupropion injection. This was accompanied by a significant decrease in prolactin concentrations, whereas the other hormones showed no statistically significant variation. It can, therefore, be concluded that, although bupropion has dual reuptake proprieties, the observed effects both at the central and at the peripheral level seem to be ruled by the dopaminergic system.
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Mondal, Partha Protim, Purba Haldar, Amit Ray y Malay Kumar Bera. "A descriptive study of experience of laparoscopic repair of retrocaval ureter in a tertiary care institute in Eastern India". Asian Journal of Medical Sciences 13, n.º 6 (1 de junio de 2022): 117–22. http://dx.doi.org/10.3126/ajms.v13i6.42683.
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Background: Retrocaval ureter (RCU) is a rare congenital anomaly. It occurs due to anomalous development of inferior vena cava (IVC) and not ureter. Here, we describe our experience in surgical techniques and operative results of laparoscopic reconstruction for patients with RCU. Aims and Objectives: The aims of this study were to obtain information regarding clinical presentation, demographic profiles, investigations, indications for intervention, postoperative complications of laparoscopic repair of retrocaval repair, and also to develop laparoscopic surgical skill without causing any untoward effects to the patients. Materials and Methods: Twelve patients with RCU were enrolled in this study. The mean age was 32.4-years-old (23–37 years). All patients were preoperatively evaluated with different relevant imaging modalities. Laparoscopic surgery with transperitoneal approach with insertion of double-j stent was performed to all patients by same surgeon without excision of compressed ureter. Post-operative follow-up was done with ultrasonography every 3 months and repeat DTPA renogram every 6 months for 2.4 years. Results: All operations were completed laparoscopically without conversion to open surgery. There was no obstruction or symptom after the mean follow-up of 2.4 years. Conclusion: Transperitoneal laparoscopic repair is a feasible, safe, and effective modality of The treatment for RCU. Careful dissection along the planes with good respect to tissue and proper hemostasis during each step is the key to success for laparoscopic repair of RCU.
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Leeman, M., P. Lejeune, J. Closset, J. L. Vachiery, C. Melot y R. Naeije. "Effects of PEEP on pulmonary hemodynamics in intact dogs with oleic acid pulmonary edema". Journal of Applied Physiology 69, n.º 6 (1 de diciembre de 1990): 2190–96. http://dx.doi.org/10.1152/jappl.1990.69.6.2190.
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The effects of positive end-expiratory pressure (PEEP) on the pulmonary circulation were studied in 14 intact anesthetized dogs with oleic acid (OA) lung injury. Transmural (tm) mean pulmonary arterial pressure (Ppa)/cardiac index (Q) plots with transmural left atrial pressure (Pla) kept constant were constructed in seven dogs, and Ppa(tm)/PEEP plots with Q and Pla(tm) kept constant were constructed in seven other dogs. Q was manipulated by using a femoral arteriovenous bypass and a balloon catheter inserted in the inferior vena cava. Pla was manipulated using a balloon catheter placed by thoracotomy in the left atrium. Ppa(tm)/Q plots were essentially linear. Before OA, the linearly extrapolated pressure intercept of the Ppa(tm)/Q relationship approximated Pla(tm). OA (0.09 ml/kg into the right atrium) produced a parallel shift of the Ppa(tm)/Q relationship to higher pressures; i.e., the extrapolated pressure intercept increased while the slope was not modified. After OA, 4 Torr PEEP (5.4 cmH2O) had no effect on the Ppa(tm)/Q relationship and 10 Torr PEEP (13.6 cmH2O) produced a slight, not significant, upward shift of this relationship. Changing PEEP from 0 to 12 Torr (16.3 cmH2O) at constant Q before OA led to an almost linear increase of Ppa(tm) from 14 +/- 1 to 19 +/- 1 mmHg. After OA, Ppa(tm) increased at 0 Torr PEEP but changing PEEP from 0 to 12 Torr did not significantly affect Ppa(tm), which increased from 19 +/- 1 to 20 +/- 1 mmHg. These data suggest that moderate levels of PEEP minimally aggravate the pulmonary hypertension secondary to OA lung injury.
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Aalaei-Andabili, Seyed Hossein, Anthony A. Bavry, Calvin Choi, George Arnaoutakis, R. David Anderson y Thomas M. Beaver. "Percutaneous Inferior Vena Cava Valve Implantation May Improve Tricuspid Valve Regurgitation and Cardiac Output: Lessons Learned". Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery 15, n.º 6 (26 de octubre de 2020): 577–80. http://dx.doi.org/10.1177/1556984520957144.
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Tricuspid valve regurgitation (TR) can be associated with poor prognosis. Transcatheter valve technology was adopted to treat the upstream effects of severe TR by placing a transcatheter valve in the inferior vena cava (IVC). In this study, we report off-label transcatheter valve implantation into the stented IVC in patients with severe TR for compassionate use. From September 2018 to February 2020, 6 inoperable patients with severe TR who failed medical treatment underwent percutaneous caval valve implantation (CAVI). Severity of TR was confirmed by intraoperative transesophageal echocardiography. Z-stents (Cook, Inc., Bloomington, IN, USA) were placed in the proximal IVC, and then a transcatheter valve was deployed in the suprahepatic cava without rapid pacing. Six patients, 2 females and 4 males, with a mean ± SD age of 74.7 ± 8.0 years were included. The procedure was successfully performed in all 6 patients (100%) employing a 29-mm SAPIEN 3 valve (Edwards Lifesciences, Irvine, CA, USA) with supranominal volume. No procedural complication was detected. At 30 days, TR improved from severe to trace in 1 patient, to mild-moderate in 3 patients, and 2 patients remained with severe TR. Among patients with improved TR, left ventricular ejection fraction increased from 47.5% ± 18.5% to 55% ± 20.4% ( P = 0.014). No patient had readmission at 30 days. Four patients needed rehospitalization within 6 months. Percutaneous CAVI is feasible and can be considered as a short-term palliative measure in patients with severe TR. CAVI can improve TR and potentially improve cardiac output in selected patients.
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Brown, J. N. y A. L. Nuttall. "Autoregulation of cochlear blood flow in guinea pigs". American Journal of Physiology-Heart and Circulatory Physiology 266, n.º 2 (1 de febrero de 1994): H458—H467. http://dx.doi.org/10.1152/ajpheart.1994.266.2.h458.
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Autoregulation of blood flow in the inner ear following uncontrolled changes in systemic blood pressure (BP), which was induced by the application of pharmacological agents that cause local and/or systemic vascular effects, has been reported in previous studies. In the current study, carotid BP was systematically manipulated without drugs, while the resulting cochlear blood flow (CBF) changes were measured using a laser Doppler flowmeter (LDF). Anesthesized guinea pigs were used, and the probe of a LDF was held against the ventral-posterior portion of the surgically exposed cochlea. A mechanical occluder was placed around the descending aorta or the inferior vena cava. BP could be elevated or lowered over a wide range and was held stable during 2-min occlusions. The mean level (+/- SD) of regulation (% delta CBF/% delta BP) for BP changes less than +/- 35% of preocclusion baseline was 0.24 +/- 0.2 (or 0.18 +/- 0.2 if BP is corrected by subtracting central venous pressure). Significant regulation occurred for BP between 20 and 70 mmHg. A demonstration of the cochlear origin of the regulatory response was obtained by “pharmacological blockade” following topical application of the vasodilator, sodium nitroprusside, to the cochlea. In this condition, CBF changed in nearly direct proportion to BP.
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Medini, F., L. Menif, G. Jmii, F. Ghali, M. Zeghal, L. Robbana, S. Derouiche y W. Melki. "Doctor I have painful erections". European Psychiatry 33, S1 (marzo de 2016): S547. http://dx.doi.org/10.1016/j.eurpsy.2016.01.2020.
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IntroductionIschemic (veno-occlusive, low flow) priapism is a painful and persistent penile erection unrelated to sexual desire or stimulation. In some cases, it is an adverse event of antipsychotic medications.Materials and methodsAn Internet search was initiated using the search engines: Direct Sciences; Medline and keywords “Penile erection; priapism; Antipsychotic agents; Side effects” and we illustrated our literature review by a clinical vignette of a man aged 38 years followed for schizophrenia placed under Fluphenazine 125 mg/month from 5 years who consulted us in may 2015 because of priapism and he described painful and prolonged erection episodes evolving for approximately 5 days.DiscussionMedical literature mentions many cases of venous priapism in patients treated by conventional or atypical neuroleptics. About 30% of venous priapisms could be related to drugs of which approximately 50% to neuroleptics. This side effect is related to alpha1-adrenergic blocking properties of these treatments, more or less important depending on the drugs in this class. After emergency treatment, the priapism is the problem of the continued neuroleptic treatment. The substitution of one molecule by another alpha-1 blocking properties to the less marked is recommended.ConclusionThe venous priapism is a uro-andrological emergency requiring prompt treatment to prevent erectile sequelae.Disclosure of interestThe authors have not supplied their declaration of competing interest.