The use of photosynthesis inhibitor (DCMU) for in situ metabolic and primary production studies on soft bottom benthos

A selective chemical photosynthesis inhibitor, DCMU (Dichorophenyl-dimethylurea), dissolved in DMSO (Dimethyl sulfoxide) was substituted for the dark incubation method commonly used to measure the oxygen consumption in metabolic and primary production studies. We compared oxygen fluxes during light incubations with DCMU and dark incubations procedure, on soft bottom benthos. For this purpose, we studied the effects of different DCMU concentrations. A concentration of 5.10-5 mol 1-1 inside a clear incubation enclosure completely inhibits photosynthesis without affecting the metabolism of soft bottom benthos. (Résumé d'auteur

Oxygen and carbon dioxide fluxes at the water-sediment interface of a tropical lagoon

Oxygen demand, carbon dioxide release and total alkalinity shift were calculated from changes in oxygen, pH and total alkalinity produced by bottom dark incubations at the water-sediment interface of the 3 bottom types identified in a southwest lagoon in New Caledonia. Total sediment oxygen demand (AO?) was corrected from nonbioloyical oxygen demand (NBOD) In order to obtain the apparent biological activity (AOlO)T.o tal carbon dioxide flux (AC02)w as corrected from total alkalinity shift in order to estimate organic carbon processes. The resulting mean carbon dioxide flux (ACOzO= 2.58 mm01 m-' h-', SE = 0.12) exceeded biological oxygen demand (AO," = 1.60 mm01 m-' h-', SE = 0.08). The highly significant ratio estimates from functional regression lines of ACO," on A 0 2 and ACOzo on AOzO gave a total community respiratory quotient (CRQ) of 1.17 (SE = 0.06) and an organic respiratory quotient (CRQO)i,n volving only direct biological processes, of 1.42 (SE = 0.07) for the lagoon. The significance and the use of these ratios are discussed in order to calculate the anaerobic metabolism proportion (40.3 % of total metabolism for an aerobic respiratory quotient of 0.85). Thus, the simultaneous measurement in the field of O2 fluxes and CO2 fluxes, corrected from appropriate alkalinity changes, allows a rapid approach for estimating carbon production at the water-sediment interface of undisturbed communities

Proving Tree Algorithms for Succinct Data Structures

Succinct data structures give space-efficient representations of large amounts of data without sacrificing performance. They rely on cleverly designed data representations and algorithms. We present here the formalization in Coq/SSReflect of two different tree-based succinct representations and their accompanying algorithms. One is the Level-Order Unary Degree Sequence, which encodes the structure of a tree in breadth-first order as a sequence of bits, where access operations can be defined in terms of Rank and Select, which work in constant time for static bit sequences. The other represents dynamic bit sequences as binary balanced trees, where Rank and Select present a low logarithmic overhead compared to their static versions, and with efficient insertion and deletion. The two can be stacked to provide a dynamic representation of dictionaries for instance. While both representations are well-known, we believe this to be their first formalization and a needed step towards provably-safe implementations of big data

Ambivalent Types for Principal Type Inference with GADTs (extended version)

GADTs, short for Generalized Algebraic DataTypes, which allow constructors of algebraic datatypes to be non-surjective, have many useful applications. However, pattern matching on GADTsintroduces local type equality assumptions, which are a source of ambiguities that may destroy principal types---and must be resolved by type annotations. We introduce ambivalent types to tighten the definition of ambiguities and better confine them, so that type inference has principal types, remains monotonic, and requires fewer type annotations

Etude quantitative du macrobenthos dans le lagon des îles Chesterfield : liste taxonomique, densités et biomasses

Au cours de la campagne CORAIL 2 réalisée dans le lagon des Chesterfield à bord du N.O. ALIS, le macrobenthos des fonds meubles a été échantillonné sur 105 stations, à l'aide d'une benne Smith-McIntyre. Sur chacune, le sédiment a été prélevé sur une surface de 0.5 m2 et tamisé sur mailles de 2 mm pour isoler la faune et la flore. Un total de 290 taxons a été identifié. Le présent document regroupe les résultats exprimés en nombre d'individus, en poids sec et en poids sec sans cendre; il constitue la base de données faunistiques et floristiques des études benthiques quantitatives dans le lagon des Chesterfield. (Résumé d'auteur

Safe zero-cost coercions for Haskell

Generative type abstractions – present in Haskell, OCaml, and other languages – are useful concepts to help prevent programmer errors. They serve to create new types that are distinct at compile time but share a run-time representation with some base type. We present a new mechanism that allows for zero-cost conversions between generative type abstractions and their representations, even when such types are deeply nested. We prove type safety in the presence of these conversions and have implemented our work in GHC

Etude quantitative du benthos dans le lagon d'Ouvéa : liste taxonomique, densités et biomasses du macrobenthos, ATP, pigments photosynthétiques et matière organique dans le sédiment = Ouvea lagoon benthos quantitative study : taxonomic checklist, macrobenthos densities and biomasses, ATP, photosynthetic pigments and organic matter in the sediment

Le benthos du lagon d'Ouvéa a été étudié sur 62 stations régulièrement réparties. Sur chaque station, l'échantillonnage a compris 10 prélèvements réalisés à l'aide d'une benne Smith McIntyre de O.1m2 et une collecte en plongée de la mégafaune (>20 mm) sur une radiale de 100 m2. Des échantillons ont également été prélevés à l'aide de carottes de 5.31 cm2 pour mesurer les quantités d'ATP, de pigments photosynthétiques et le pourcentage de matière organique dans le sédiment. Les résultats sont exprimés pour chaque taxon, en nombre d'individus, en poids sec sans cendre par m2. Un total de 341 taxons a été identifié. Le présent document décrit les méthodes mises en oeuvre et présente les résultats obtenus au cours de l'étude. (Résumé d'auteur