Point de vue sur l'avenir de la production laitière en Bretagne

Il s'agit d'un texte qui a servi de base à une série d'exposés à des agriculteurs au cours de l'hiver 1976-19'77

Sur l'évolution du monde rural en Bretagne depuis la Seconde Guerre Mondiale

Sur l'évolution du monde rural en Bretagne depuis la Seconde Guerre Mondial

RELATIONSHIP OF RACCOON ROAD-KILL DATA TO HIGH-DENSITY MARINE TURTLE NESTING

Four ycars of data from a hiyh-density n~arine turtle nesting hcach at John D. MacArthur Beach Statc Park, Florida wcrc examined along with data on raccoon (Procyon lotor.) ruad-kills from adjaccnt roads, and data on park attendance (as an index of local traffic) to make infcrcnces about raccoon activity patterns relative to turtle ncsting. Raccoon road-kills were found Lo diminish subsiantially during turtle nesting, even though local traffic was constant or increasing. Opossums (Didelphis virginiana). the only other maminal consistcntly foluid as road-kills, did not show a decrease during ti~rtlen esting season, but they are not known as a primary predator of turtle nests. We concluded that duriny turtlc nestiny raccoons are drawn to the beach to prey on the abundant food resource of turtle eggs, and they do not leave the beach until the end of turtle nesting season. High nu~nbcrso f raccoon road-kills during the fall-wintcr, followed by a decrease in the spring around the start of turtle nesting season, might be ured as indicators to initiate management actions to protect turtle nests

Use of roadkill data to index and relate raccoon activity at a heavily predated, high-density marine turtle nesting beach

Four years of data from a high-density marine turtle nesting beach at John D. MacArthur Beach State Park, Florida were examined along with data on raccoon road-kills from adjacent roads, and data on park attendance (as an index of local traffic) to make inferences about raccoon activity patterns relative to turtle nesting. Raccoon road-klls were found to diminish substantially during turtle nesting, even though local traffic was constant or increasing. Opossums, the only other mammal consistently found as road-kills, did not show a decrease during turtle nesting season, but they are not known as a primary predator of turtle nests. We concluded that during turtle nesting raccoons are drawn to the beach to prey on the abundant nesting raccoons food resource of turtle eggs, and they do not leave the beach until the end of turtle nesting season. High numbers of raccoon road-kills during the fall-winter, followed by a decrease in the spring around the start of turtle nesting season, might be used as indicators to initiate management actions to protect turtle nests

A Renormalization Group Analysis of Coupled Superconducting and Stripe Order in 1+1 Dimensions

In this paper we perform a renormalization group analysis on the 1+1 dimensional version of an effective field theory (previously proposed by Dung-Hai Lee, cond-mat/011393) describing (quantum) fluctuating stripe and superconductor orders. We find four possible phases corresponding to stripe order/disorder combined with superconducting order/disorder.Comment: 8 pages, 3 figures, revte

Efficient Algorithm on a Non-staggered Mesh for Simulating Rayleigh-Benard Convection in a Box

An efficient semi-implicit second-order-accurate finite-difference method is described for studying incompressible Rayleigh-Benard convection in a box, with sidewalls that are periodic, thermally insulated, or thermally conducting. Operator-splitting and a projection method reduce the algorithm at each time step to the solution of four Helmholtz equations and one Poisson equation, and these are are solved by fast direct methods. The method is numerically stable even though all field values are placed on a single non-staggered mesh commensurate with the boundaries. The efficiency and accuracy of the method are characterized for several representative convection problems.Comment: REVTeX, 30 pages, 5 figure

Sulfide enrichment along igneous layer boundaries in the lower oceanic crust: IODP Hole U1473A, Atlantis Bank, Southwest Indian Ridge

Reactive porous or focused melt flows are common in crystal mushes of mid-ocean ridge magma reservoirs. Although they exert significant control on mid-ocean ridge magmatic differentiation, their role in metal transport between the mantle and the ocean floor remains poorly constrained. Here we aim to improve such knowledge for oceanic crust formed at slow-spreading centers (approximately half of present-day oceanic crust), by focusing on specific igneous features where sulfides are concentrated. International Ocean Discovery Program (IODP) Expedition 360 drilled Hole U1473A 789 m into the lower crust of the Atlantis Bank oceanic core complex, located at the Southwest Indian Ridge. Coarse-grained (5–30 mm) olivine gabbro prevailed throughout the hole, ranging locally from fine- (<1 mm), to very coarse-grained (>30 mm). We studied three distinct intervals of igneous grain size layering at 109.5–110.8, 158.0–158.3, and 593.0–594.4 meters below seafloor to understand the distribution of sulfides. We found that the layer boundaries between the fine- and coarse-grained gabbro were enriched in sulfides and chalcophile elements. On average, sulfide grains throughout the layering were composed of pyrrhotite (81 vol.%; Fe1-xS), chalcopyrite (16 vol.%; CuFeS2), and pentlandite (3 vol.%; [Ni,Fe,Co]9S8), which reflect paragenesis of magmatic origin. The sulfides were most commonly associated with Fe-Ti oxides (titanomagnetites and ilmenites), amphiboles, and apatites located at the interstitial positions between clinopyroxene, plagioclase, and olivine. Pentlandite exsolution textures in pyrrhotite indicate that the sulfides formed from high-temperature sulfide liquid separated from mafic magma that exsolved upon cooling. The relatively homogenous phase proportion within sulfides along with their chemical and isotopic compositions throughout the studied intervals further support the magmatic origin of sulfide enrichment at the layer boundaries. The studied magmatic layers were likely formed as a result of intrusion of more primitive magma (fine-grained gabbro) into the former crystal mush (coarse-grained gabbro). Sulfides from the coarse-grained gabbros are Ir-Platinum Group Element-rich (PGE; i.e., Ir, Os, Ru) but those from the fine-grained gabbros are Pd-PGE-rich (i.e., Pd, Pt, Rh). Notably, the sulfides from the layer boundaries are also enriched in Pd-PGEs, and therefore elevated sulfide contents at the boundaries were likely related to the new intruding melt. Because S concentration at sulfide saturation level is dependent on the Fe content of the melt, sulfide crystallization may have been caused by FeO loss, both via crystallization of late-precipitating oxides at the boundaries, and by exchange of Fe and Mg between melt and Fe-bearing silicates (olivine and clinopyroxene). The increased precipitation of sulfide grains at the layer boundaries might be widespread in the lower oceanic crust, as also observed in the Semail ophiolite and along the Mid-Atlantic Ridge. Therefore, this process might affect the metal budget of the global lower oceanic crust. We estimate that up to ∼20% of the Cu, ∼8% of the S, and ∼84% of the Pb of the oceanic crust inventory is accumulated at the layer boundaries only from the interaction between crystal mush and new magma. © 2022 The Author