Le thon : enjeux et stratégies pour l'océan Indien

Le problème de l'accès aux ressources et aux droits de pêche est une des questions majeures qui se pose à l'échelle des ressources mondiales et doit être abordé et structuré selon deux voies : le mode d'allocation des droits de pêche et le mode de retour des revenus de l'exploitation au propriétaire détenteur gestionnaire initial, légitime. Ce problème ne se pose pas dans une pêcherie ouverte en libre accès ou non gérée, bien que la participation à cette forme d'exploitation non réglementée induit une forme de rente ou de quasi-rente. Le document présente une définition de la rente économique dans le contexte d'une pêcherie gérée, réglementée et la distingue d'autres types de rentes qui peuvent provenir de la mise en oeuvre d'autres facteurs de production. La mesure de cette rente de pêche est ainsi décrite en illustrant les principales difficultés provenant de l'évaluation précise de la valeur de cette rente. Les bénéfices et les coûts d'opération de pêche par des flottilles étrangères sont examinés dans le contexte et la perspective d'une participation des propriétaires de la ressource locale, domestique, dans la pêcherie. (Résumé d'auteur

Nonlocality in mesoscopic Josephson junctions with strip geometry

We study the current in a clean superconductor-normal-metal-superconductor junction of length d and width w in the presence of an applied magnetic field H. We show that both the geometrical pattern of the current density and the critical current as a function of the total flux in the junction, depend on the ratio of the Josephson vortex distance a_0 and the range r of the nonlocal electrodynamics. In particular, the critical current has the periodicity of the superconducting flux quantum only for r<a_0 and acquires, due to boundary effects, the double (pseudo-) periodicity for strong nonlocality, r>a_0. Comparing our results to recent experiments of Heida et al. [Phys. Rev. B 57, R5618 (1998)] we find good agreement.Comment: 4 pages, 5 figures, to be published in the RC section of Phys. Rev.

TGFβ inhibition stimulates collagen maturation to enhance bone repair and fracture resistance in a murine myeloma model

Multiple myeloma is a plasma cell malignancy that causes debilitating bone disease and fractures, in which TGFβ plays a central role. Current treatments do not repair existing damage and fractures remain a common occurrence. We developed a novel low tumour phase murine model mimicking the plateau phase in patients, as we hypothesized this would be an ideal time to treat with a bone anabolic. Using in vivo microCT we show substantial and rapid bone lesion repair (and prevention) driven by SD‐208 (TGFβ receptor I kinase inhibitor) and chemotherapy (bortezomib and lenalidomide) in mice with human U266‐GFP‐luc myeloma. We discovered that lesion repair occurred via an intramembranous fracture repair‐like mechanism and that SD‐208 enhanced collagen matrix maturation to significantly improve fracture resistance. Lesion healing was associated with VEGFA expression in woven bone, reduced osteocyte‐derived PTHrP, increased osteoblasts, decreased osteoclasts and lower serum TRACP‐5b. SD‐208 also completely prevented bone lesion development mice with aggressive JJN3 tumors, and was more effective than an anti‐TGFβ neutralizing antibody (1D11). We also discovered that SD‐208 promoted osteoblastic differentiation (and overcame the TGFβ‐induced block in osteoblastogenesis) in myeloma patient bone marrow stromal cells in vitro, comparable to normal donors. The improved bone quality and fracture‐resistance with SD‐208 provides incentive for clinical translation to improve myeloma patient quality of life by reducing fracture risk and fatality

Fuzzy logic modelling of snow leopard populations in response to threats from climate change

The snow leopard population in Kazakhstan represents a small but important component of the species range, making up around 2.7% of the global range, of which 18,673 km2 lies within protected areas. The most recent population estimate, by Jackson et al. (2008), suggests that there are around 180-200 individuals. Prior to this study there were no reliable estimates of snow leopard numbers in Almaty State Nature Reserve, one of the only two stable populations of snow leopards in Kazakhstan. In total 40 camera traps were deployed for a total of 5152 traps nights and yielded 50 independent capture events of snow leopards (with between 1 and 10 images per event), 275 capture events of primary prey and 68 capture events of secondary prey. The study capture rate of 0.97 independent capture events per 100 trap nights is at the higher end of the range experienced by other studies (see McCarthy et al., 2008) and mark-recapture modelling estimated 11-18 individual snow leopards in the study area which suggests density between 4.4 and 7.2 individuals per 100km2. Our population estimate for the whole reserve is 39.6 individuals, with a standard error of 5.44536 individuals and a 95% confidence interval of 39 to 64. Analysis of movement patterns suggests that individuals frequently crossed valley bottoms and used densely forested habitat in winter, which may indicated prey switching from ibex to forest ungulates. The University of Cumbria has developed a fuzzy logic model which aggregates a wide range of socio-economic and ecological data and provides a tool that can be used to inform the sustainable natural resource and landscape management decision-making process. Our model predicts the consistent negative impact of climate change (warming) at elevations below the tree line; this is particularly significant as the potential positive impacts for snow leopards at high elevation are slower to kick in thereby increasing the habitat squeeze associated with climate change in mountain habitats

Structural and Functional Changes across the Visual Cortex of a Patient with Visual Form Agnosia

Loss of shape recognition in visual-form agnosia occurs without equivalent losses in the use of vision to guide actions, providing support for the hypothesis of two visual systems (for “perception” and “action”). The human individual DF received a toxic exposure to carbon monoxide some years ago, which resulted in a persisting visual-form agnosia that has been extensively characterized at the behavioral level.We conducted a detailed high-resolution MRI study of DF’s cortex, combining structural andfunctional measurements.We present the first accurate quantification of the changes in thickness across DF’s occipital cortex, finding the most substantial loss in the lateral occipital cortex (LOC). There are reduced white matter connections between LOC and other areas. Functional measures show pockets of activity that survive within structurally damaged areas. The topographic mapping of visual areas showed that ordered retinotopic maps were evident for DF in the ventral portions of visual cortical areas V1, V2, V3, and hV4. Although V1 shows evidence of topographic order in its dorsal portion, such maps could not befound inthe dorsal parts of V2 and V3. We concludethat it is not possibleto understandfully the deficits in object perception in visual-form agnosia without the exploitation of both structural and functional measurements. Our results also highlight for DF the cortical routes through which visual information is able to pass to support her well-documented abilities to use visual information to guide actions

Split-off dimer defects on the Si(001)2x1 surface

Dimer vacancy (DV) defect complexes in the Si(001)2x1 surface were investigated using high-resolution scanning tunneling microscopy and first principles calculations. We find that under low bias filled-state tunneling conditions, isolated 'split-off' dimers in these defect complexes are imaged as pairs of protrusions while the surrounding Si surface dimers appear as the usual 'bean-shaped' protrusions. We attribute this to the formation of pi-bonds between the two atoms of the split-off dimer and second layer atoms, and present charge density plots to support this assignment. We observe a local brightness enhancement due to strain for different DV complexes and provide the first experimental confirmation of an earlier prediction that the 1+2-DV induces less surface strain than other DV complexes. Finally, we present a previously unreported triangular shaped split-off dimer defect complex that exists at SB-type step edges, and propose a structure for this defect involving a bound Si monomer.Comment: 8 pages, 7 figures, submitted to Phys. Rev.

Subjective expectations of medical expenditures and insurance in rural Ethiopia

Little is known about perceptions of medical expenditure risks despite their presumed relevance to health insurance demand. This paper reports on a unique elicitation of subjective probabilities of medical expenditures from rural Ethiopians who are offered the opportunity to purchase health insurance. We find that expectations are positively correlated with past expenses to a degree that exceeds the serial correlation in realized expenditures, suggesting overestimation of persistence and underestimation of the potential gains from insurance. Despite the fact that forecast expenditures do predict realized expenditures to some extent, there is no evidence that expectations influence the decision to take out health insurance, although plans to insure are positively related to the perce

Dilatonic global strings

We examine the field equations of a self-gravitating global string in low energy superstring gravity, allowing for an arbitrary coupling of the global string to the dilaton. Massive and massless dilatons are considered. For the massive dilaton the spacetime is similar to the recently discovered non-singular time-dependent Einstein self-gravitating global string, but the massless dilaton generically gives a singular spacetime, even allowing for time-dependence. We also demonstrate a time-dependent non-singular string/anti-string configuration, in which the string pair causes a compactification of two of the spatial dimensions, albeit on a very large scale.Comment: 18 pages RevTeX, 3 figures, references amende

Measurement of νˉμ\bar{\nu}_{\mu} and νμ\nu_{\mu} charged current inclusive cross sections and their ratio with the T2K off-axis near detector

We report a measurement of cross section $\sigma(\nu_{\mu}+{\rm nucleus}\rightarrow\mu^{-}+X)$ and the first measurements of the cross section $\sigma(\bar{\nu}_{\mu}+{\rm nucleus}\rightarrow\mu^{+}+X)$ and their ratio $R(\frac{\sigma(\bar \nu)}{\sigma(\nu)})$ at (anti-)neutrino energies below 1.5 GeV. We determine the single momentum bin cross section measurements, averaged over the T2K $\bar{\nu}/\nu$-flux, for the detector target material (mainly Carbon, Oxygen, Hydrogen and Copper) with phase space restricted laboratory frame kinematics of $\theta_{\mu}$500 MeV/c. The results are $\sigma(\bar{\nu})=\left( 0.900\pm0.029{\rm (stat.)}\pm0.088{\rm (syst.)}\right)\times10^{-39}$ and $\sigma(\nu)=\left( 2.41\ \pm0.022{\rm{(stat.)}}\pm0.231{\rm (syst.)}\ \right)\times10^{-39}$in units of cm$^{2}$/nucleon and$R\left(\frac{\sigma(\bar{\nu})}{\sigma(\nu)}\right)= 0.373\pm0.012{\rm (stat.)}\pm0.015{\rm (syst.)}$.Comment: 18 pages, 8 figure

Magnetic Field Amplification in Galaxy Clusters and its Simulation

We review the present theoretical and numerical understanding of magnetic field amplification in cosmic large-scale structure, on length scales of galaxy clusters and beyond. Structure formation drives compression and turbulence, which amplify tiny magnetic seed fields to the microGauss values that are observed in the intracluster medium. This process is intimately connected to the properties of turbulence and the microphysics of the intra-cluster medium. Additional roles are played by merger induced shocks that sweep through the intra-cluster medium and motions induced by sloshing cool cores. The accurate simulation of magnetic field amplification in clusters still poses a serious challenge for simulations of cosmological structure formation. We review the current literature on cosmological simulations that include magnetic fields and outline theoretical as well as numerical challenges.Comment: 60 pages, 19 Figure