Reef response to sea-level and environmental changes during the last deglaciation: Integrated Ocean Drilling Program Expedition 310, Tahiti Sea Level

The last deglaciation is characterized by a rapid sea-level rise and coeval abrupt environmental changes. The Barbados coral reef record suggests that this period has been punctuated by two brief intervals of accelerated melting (meltwater pulses, MWP), occurring at 14.08-13.61 ka and 11.4-11.1 ka (calendar years before present), that are superimposed on a smooth and continuous rise of sea level. Although their timing, magnitude, and even existence have been debated, those catastrophic sea-level rises are thought to have induced distinct reef drowning events. The reef response to sea-level and environmental changes during the last deglacial sea-level rise at Tahiti is reconstructed based on a chronological, sedimentological, and paleobiological study of cores drilled through the relict reef features on the modern forereef slopes during the Integrated Ocean Drilling Program Expedition 310, complemented by results on previous cores drilled through the Papeete reef. Reefs accreted continuously between 16 and 10 ka, mostly through aggradational processes, at growth rates averaging 10 mm yr-1. No cessation of reef growth, even temporary, has been evidenced during this period at Tahiti. Changes in the composition of coralgal assemblages coincide with abrupt variations in reef growth rates and characterize the response of the upward-growing reef pile to nonmonotonous sea-level rise and coeval environmental changes. The sea-level jump during MWP 1A, 16 ± 2 m of magnitude in ~350 yr, induced the retrogradation of shallow-water coral assemblages, gradual deepening, and incipient reef drowning. The Tahiti reef record does not support the occurrence of an abrupt reef drowning event coinciding with a sea-level pulse of ~15 m, and implies an apparent rise of 40 mm yr-1 during the time interval corresponding to MWP 1B at Barbados. © 2012 Geological Society of America

Tiling groupoids and Bratteli diagrams

Let T be an aperiodic and repetitive tiling of R^d with finite local complexity. Let O be its tiling space with canonical transversal X. The tiling equivalence relation R_X is the set of pairs of tilings in X which are translates of each others, with a certain (etale) topology. In this paper R_X is reconstructed as a generalized "tail equivalence" on a Bratteli diagram, with its standard AF-relation as a subequivalence relation. Using a generalization of the Anderson-Putnam complex, O is identified with the inverse limit of a sequence of finite CW-complexes. A Bratteli diagram B is built from this sequence, and its set of infinite paths dB is homeomorphic to X. The diagram B is endowed with a horizontal structure: additional edges that encode the adjacencies of patches in T. This allows to define an etale equivalence relation R_B on dB which is homeomorphic to R_X, and contains the AF-relation of "tail equivalence".Comment: 34 pages, 4 figure

Droit de la construction : de la jurisprudence à la pratique notariale

"Parce que le contentieux de la construction concerne les notaires à bien des égards, cette nouvelle chronique, rédigée par des universitaires et des praticiens, a pour objectif premier de brosser un panorama des décisions importantes rendues au cours de l\u27année 2012 en la matière. Les signataires de ces lignes ont ensuite cherché, dans le cadre de cette collaboration entre chercheurs et notaires, à enrichir leurs commentaires de conseils pratiques. Ainsi, au cours de l\u27année écoulée, la Cour de cassation s\u27est prononcée sur des questions générales d\u27organisation de l\u27immeuble, précisant la liberté de choix entre le statut de la copropriété et la division en volumes ou revenant sur les règles applicables aux travaux réalisés sur un mur mitoyen. Des précisions ont également été apportées sur le champ d\u27application de la responsabilité décennale des constructeurs, puisqu\u27il a été rappelé que le vendeur même non professionnel d\u27un immeuble rénové peut, à certaines conditions, engager sa responsabilité décennale, de même que cette cause de responsabilité est également susceptible de s\u27appliquer lorsque les dommages affectant un immeuble neuf causent des préjudices à des tiers ou se matérialisent par un simple risque d\u27écroulement, sans que la catastrophe ne soit encore survenue. Un arrêt important précise en outre, dans le domaine des assurances, la distinction entre la faute lourde, couverte, et celle intentionnelle, dont l\u27assureur ne répondra pas. On relèvera finalement trois décisions importantes en matière de vente d\u27immeubles à construire. Deux concernent la rédaction des actes, quant à la distinction entre les notions d\u27achèvement et de livraison d\u27une part, puis relativement aux clauses d\u27allongement de délai de livraison pour intempéries, d\u27autre part. Le dernier revient sur la question importante la rénovation en précisant l\u27étendue de la responsabilité du notaire dans le choix entre le modèle de la vente en l\u27état futur d\u27achèvement et celui de la vente d\u27immeuble à rénover." Gwenaëlle Durand-Pasquie

A model for gelation with explicit solvent effects: Structure and dynamics

We study a two-component model for gelation consisting of $f$-functional monomers (the gel) and inert particles (the solvent). After equilibration as a simple liquid, the gel particles are gradually crosslinked to each other until the desired number of crosslinks has been attained. At a critical crosslink density the largest gel cluster percolates and an amorphous solid forms. This percolation process is different from ordinary lattice or continuum percolation of a single species in the sense that the critical exponents are new. As the crosslink density $p$ approaches its critical value $p_c$, the shear viscosity diverges: $\eta(p)\sim (p_c-p)^{-s}$ with $s$ a nonuniversal concentration-dependent exponent.Comment: 6 pages, 9 figure

Pure point diffraction implies zero entropy for Delone sets with uniform cluster frequencies

Delone sets of finite local complexity in Euclidean space are investigated. We show that such a set has patch counting and topological entropy 0 if it has uniform cluster frequencies and is pure point diffractive. We also note that the patch counting entropy is 0 whenever the repetitivity function satisfies a certain growth restriction.Comment: 16 pages; revised and slightly expanded versio