Regimes of low-frequency variability in a three-layer quasi-geostrophic ocean model

The temporal variability of the midlatitude double-gyre wind-driven ocean circulation is studied in a three-layer quasi-geostrophic model over a broad range in parameter space. Four different types of flow regimes are found, each characterized by a specific time-mean state and spatio-temporal variability. As the lateral friction is decreased, these regimes are encountered in the following order: the viscous antisymmetric regime, the asymmetric regime, the quasi-homoclinic regime and the inertial antisymmetric regime. The variability in the viscous and the inertial antisymmetric regimes (at high and low lateral friction, respectively) is mainly caused by Rossby basin modes. Low-frequency variability, i.e.on interannual to decadal time-scales, is present in the asymmetric and quasi-homoclinic regime and can be related to relaxation oscillations originating from low-frequency gyre modes. The focus of this paper is on the mechanisms of the transitions between the different regimes. The transition from the viscous antisymmetric regime to the asymmetric regime occurs through a symmetry-breaking pitchfork bifurcation. There are strong indications that the quasi-homoclinic regime is introduced through the existence of a homoclinic orbit. The transition to the inertial antisymmetric regime is due to the symmetrization of the time-mean state zonal velocity field through rectification effects

The turbulent oscillator : a mechanism of low-frequency variability of the wind-driven ocean gyres

Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography. 37 (2007): 2363-2386, doi:10.1175/jpo3118.1.Intrinsic low-frequency variability is studied in the idealized, quasigeostrophic, midlatitude, wind-driven ocean gyres operating at large Reynolds number. A robust decadal variability mode driven by the transient mesoscale eddies is found and analyzed. The variability is a turbulent phenomenon, which is driven by the competition between the eddy rectification process and the potential vorticity anomalies induced by changes of the intergyre transportFunding for Pavel Berloff was provided by NSF Grants OCE-0091836 and OCE- 0344094, by the U.K. Royal Society Fellowship, and by the Newton Trust Award, A. M. Hogg was supported by an Australian Research Council Postdoctoral Fellowship (DP0449851) during this work, and William K. Dewar was supported by NSF Grants OCE-0424227 and OCE-0550139

La perfusion des organes digestifs. Méthode d'étude de l'absorption

Le Bars Henri, Mollé J., Rérat Alain, Simonnet Henri. La perfusion des organes digestifs. Méthode d'étude de l'absorption. In: Bulletin de l'Académie Vétérinaire de France tome 111 n°6, 1958. pp. 305-310

Absorption des acides aminés au niveau du rumen de l’intestin grêle et du caecum chez le mouton

Demaux G., Le Bars Henri, Mollé J., Rérat Alain, Simonnet Henri. Absorption des acides aminés, au niveau du rumen, de l’intestin grêle et du cæcum chez le Mouton. In: Bulletin de l'Académie Vétérinaire de France tome 114 n°2, 1961. pp. 85-88

Play and tickling responses map to the lateral columns of the rat periaqueductal gray

The persistence of play after decortication points to a subcortical mechanism of play control. We found that global blockade of the rat periaqueductal gray with either muscimol or lidocaine interfered with ticklishness and play. We recorded vocalizations and neural activity from the periaqueductal gray of young, playful rats during interspecific touch, play, and tickling. Rats vocalized weakly to touch and more strongly to play and tickling. Periaqueductal gray units showed diverse but strong modulation to tickling and play. Hierarchical clustering based on neuronal responses to play and tickling revealed functional clusters mapping to different periaqueductal gray columns. Specifically, we observed play-neutral/tickling-inhibited and tickling/play-neutral units in dorsolateral and dorsomedial periaqueductal gray columns. In contrast, strongly play/tickling-excited units mapped to the lateral columns and were suppressed by anxiogenic conditions. Optogenetic inactivation of lateral periaqueductal columns disrupted ticklishness and play. We conclude that the lateral periaqueductal gray columns are decisive for play and laughter

Projet de conservation de la biodiversité dans la moyenne vallée du Zambèze après éradication de la mouche tsé-tsé (Zimbabwé). Etude de faisabilité d'un microprojet : le ranch communal de gibier de Gonono (Gonono communal game ranch)

Le "ranch communal de gibier de Gonono" s'inscrit dans le cadre des micro-projets proposés de manière consensuelle au Comité exécutif du "Projet de Conservation de la Biodiversité dans la Moyenne Vallée du Zambèze après l'Eradication. de la Mouche Tsé-tsé". Dans le but global d'améliorer durablement les conditions de vie de la population du Ward de Gonono, l'objectif spécifique de ce micro-projet est de mettre au point un mode local de production alternative de viande à bas prix à partir de la faune sauvage. Décidé et conçu avec les autorités du Ward, le ranch doit être progressivement géré par et pour la population du Ward. Il doit d'abord produire sur place une viande de gibier recherchée par les communautés locales qui n'y avaient accès jusqu'à présent que de manière illégale. Cette viande doit être produite à un coût modéré accessible à la population. Le ranch doit aussi permettre de conserver un espace étendu encore faiblement anthropisé en le valorisant par des productions à faible impact écologique. En phase de croisière, l'exploitation sur 3.000 hectares du peuplement multispécifique de gibier devrait permettre la fourniture annuelle de 3 0 tonnes carcasse de viande d'impala et 10. tonnes carcasse de viande d'autres espèces, soit une productivité de 13 kg carcasse de venaison par hectare. Quelques productions annexes sont aussi prévues. L'objectif économique est la couverture du prix de revient de la viande et non pas la recherche d'un profit financier. La création de ce ranch communal de gibier est une entreprise à caractère hautement innovant aux plans institutionnel et technique. Il doit donc être considéré comme une opération pilote à part entière et, à ce titre, doit pouvoir bénéficier d'un encadrement serré et d'un appui scientifique conséquent, tout au moins les premières années. (Résumé d'auteur

Nat. Hazards Earth Syst. Sci.

International audienceThe two primary causes of surf zone injuries (SZIs) worldwide, including fatal drowning and severe spinal injuries, are rip currents (rips) and shore-break waves. SZIs also result from surfing and bodyboarding activity. In this paper we address the primary environmental controls on SZIs along the high-energy meso-macro-tidal surf beach coast of southwestern France. A total of 2523 SZIs recorded by lifeguards over 186 sample days during the summers of 2007, 2009 and 2015 were combined with measured and/or hindcast weather, wave, tide, and beach morphology data. All SZIs occurred disproportionately on warm sunny days with low wind, likely because of increased beachgoer numbers and hazard exposure. Relationships were strongest for shore-break- and rip-related SZIs and weakest for surfingrelated SZIs, the latter being also unaffected by tidal stage or range. Therefore, the analysis focused on bathers. More shore-break-related SZIs occur during shore-normal incident waves with average to below-average wave height (significant wave height, Hs = 0.75-1.5 m) and around higher water levels and large tide ranges when waves break on the steepest section of the beach. In contrast, more rip-related drownings occur near neap low tide, coinciding with maximised channel rip flow activity, under shore-normal incident waves with Hs > 1.25 m and mean wave periods longer than 5 s. Addi- tional drowning incidents occurred at spring high tide, presumably due to small-scale swash rips. The composite wave and tide parameters proposed by Scott et al. (2014) are key controlling factors determining SZI occurrence, although the risk ranges are not necessarily transferable to all sites. Summer beach and surf zone morphology is interannually highly variable, which is critical to SZI patterns. The upper beach slope can vary from 0.06 to 0.18 between summers, resulting in low and high shore-break-related SZIs, respectively. Summers with coast-wide highly (weakly) developed rip channels also result in widespread (scarce) rip-related drowning incidents. With life risk defined in terms of the number of people exposed to life threatening hazards at a beach, the ability of morphodynamic models to simulate primary beach morphology characteristics a few weeks or months in advance is therefore of paramount importance for predicting the primary surf zone life risks along this coast