Conception de systèmes agricoles durables avec couverture herbacée permanente pour les Hauts de la Réunion

Dans les hauts de la Réunion, la culture itinérante traditionnelle du geranium rosat s'est sédentarisée. La fertilité n'est plus restaurée par la jachère et les rendements s'effondrent. Les couvertures végétales, à base de légumineuse ou de graminée fourragère, peuvent permettre de lutter contre l'érosion et de maintenir la fertilité des sols dans les systèmes de culture considéré

Export fluxes of calcite in the eastern equatorial Pacific from the Last Glacial Maximum to present

Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 19 (2004): PA2018, doi:10.1029/2003PA000986.The eastern equatorial Pacific (EEP) is an important center of biological productivity, generating significant organic carbon and calcite fluxes to the deep ocean. We reconstructed paleocalcite flux for the past 30,000 years in four cores collected beneath the equatorial upwelling and the South Equatorial Current (SEC) by measuring ex230Th-normalized calcite accumulation rates corrected for dissolution with a newly developed proxy for “fraction of calcite preserved.” This method produced very similar results at the four sites and revealed that the export flux of calcite was 30–50% lower during the LGM compared to the Holocene. The internal consistency of these results supports our interpretation, which is also in agreement with emerging data indicating lower glacial productivity in the EEP, possibly as a result of lower nutrient supply from the southern ocean via the Equatorial Undercurrent. However, these findings contradict previous interpretations based on mass accumulation rates (MAR) of biogenic material in the sediment of the EEP, which have been taken as reflecting higher glacial productivity due to stronger wind-driven upwelling.This research was partly supported by NSF grant OCE-0095617 and funds from the Northern Illinois University Graduate School (Loubere); the NASA Michigan Space Grant Consortium Seed Grant for summer, 2001 for 230Th analyses at WHOI (Mekik); the French Ministere de l’Education Nationale, de la Recherche et de la Technologie, and a EURODOC grant from the Region Rhone-Alpes (Pichat)

Assessment of terrestrial small mammals and a record of the critically endangered shrew Crocidura wimmeri in Banco National Park (Côte d'Ivoire)

This study investigated the small mammal community of the periurban Banco National Park (34 km2), Abidjan, Côte d'Ivoire, using identical numbers of Sherman and Longworth traps. We aimed to determine the diversity and distribution of rodents and shrews in three different habitats: primary forest, secondary forest and swamp. Using 5014 trap-nights, 91 individuals were captured that comprised seven rodent and four shrew species. The trapping success was significantly different for each species, i.e., the Longworth traps captured more soricids (31/36 shrews), whereas the Sherman traps captured more murids (37/55 mice). The most frequent species was Praomys cf. rostratus, followed by Crocidura buettikoferi, Hybomys trivirgatus and Crocidura jouvenetae. Indices of species richness (S) and diversity (H′) were greatest in primary forest, followed by secondary forest and swamp. Several expected species, such as Crocidura obscurior, were not found, whereas we captured four specimens of the critically endangered (IUCN 2012) Wimmer's shrew Crocidura wimmeri, a species that has vanished from its type locality, Adiopodoumé. Therefore, Banco National Park represents an important sanctuary, not only for plants, birds and primates, but also for other small forest vertebrate

NOBEL, LE JEU DE LA DECOUVERTE SCIENTIFIQUE

Popper a rompu avec une tradition épistémologique ancienne en introduisant une dissymétrie entre vérifiabilité et réfutation. Cette conception a d'importantes répercussions sur la manière d'envisager la croissance des connaissances scientifiques et l'activité du chercheur. La vérité, qui avait pu être considérée comme un but pour la recherche scientifique, est placée hors d'atteinte. Sans indicateur évident pour marquer le terme de ses recherches, le chercheur doit alors faire, en fonction de ses motivations, un compromis entre l'exploration des théories possibles et des manières de les tester, et l'exploitation de théories qui auront été suffisamment corroborées. Si les thèses épistémologiques de Popper sont pertinentes, ce compromis exploration/exploitation au niveau du chercheur a des conséquences notables sur le développement des connaissances scientifiques et notamment, sur la fiabilité des théories acceptées. Ce sont ces conséquences que nous nous proposons d'étudier par une approche analytique, expérimentale et computationnelle, dont nous présentons ici les grandes lignes et les premiers résultats. Au delà de préoccupations purement épistémologiques, cette étude cherche à proposer un schéma générique pour l'approche d'un vaste ensemble de phénomènes d'élaboration collective et distribuée de connaissances ou d'artefacts.découverte collective, développement de la connaissance, compromis exploration/exploitation, épistemologie popperienne, knowledge managment distribué

Laser-doppler Acoustic Probing of Granular Media with Varying Water Levels

International audienceLaboratory physical modelling and non-contacting ultrasonic techniques are frequently proposed to tackle theoretical and method- ological issues related to geophysical prospecting. We used an innovative experimental set-up to perform laser-Doppler acoustic probing of granular materials with varying water levels to target near-surface hydrogeological applications. The preliminary results presented here show a clear influence of the water level on both first arrival times and dispersion of guided waves, and significant differences in terms of amplitudes. They validate the use of such approach to benchmark recently developed methods for water saturation detection in hydrogeophysics

Effect of Fermentation on the Microbial and Nutrient Composition of Digue: A Fermented Food Obtained with Pumpkin (Cucurbita maxima) and Peanut (Arachis hypogaea)

The aim of this work was to study the evolution of microbiological and selected physicochemical parameters during the production of Digue, food obtained from the addition of the paste of roasted Arachis hypogaea (peanuts) in Yam Digue, fermented juice of Cucurbita maxima (pumpkin). The evolution of the microbial flora, the content of reducing sugars, total polyphenols, phosphorus, potassium and titratable acidity were measured during 30 days. Microbiological analysis at the start of fermentation revealed the presence of 03 groups of pathogenic germs such as staphylococci, enterobacteria and moulds with concentrations of 3.2, 3.8 and 3.24 Log10CFU/ml respectively. We also observed the presence of lactic acid bacteria (LAB) which were are the most represented bacterial flora in the medium with a microbial load of 5.2Log10CFU/ml. During fermentation, enterobacteria, staphylococci and moulds respectively reached maximum values ​​of 3.2, 3.8 and 3.2log10CFU/ml on the 7th day. However, after the 21st day, enterobacteria and mould were eliminated, unlike staphylococci which were completely inhibited only on the 28th day. The highest phosphorus and potassium contents were recorded on the 21st day with values ​​of 0.29% and 2.5% respectively. On the 14th day, the LAB yielded much higher microbial concentration of 8.9Log10CFU/ml which also led to the optimum production of titratable acidity (1.2%) in the medium. During the same period, the sugar content increased by 2.3% and the polyphenols were eliminated at 100%. The data obtained in this work reveal the elimination of microbial growth and increasing the physicochemical qualities at the 21th day with fermentation. Thus, it would be recommended for producers to ferment it for over 21 days as result of appreciable yield in terms of microbial, organoleptic and chemical qualities. Keywords: Cucurbita maxima, Digue, fermentation, nutritional, pathogenic germs DOI: 10.7176/FSQM/103-05 Publication date: December 31st 2020

Moiré methods for the protection of documents and products: A short survey

Moiré effects have long been used for various applications in many different fields, including metrology, strain analysis, optical alignment, etc. In the present survey we describe some of the main applications of the moiré effect in the field of document and product security. We review the main families of moiré-based anticounterfeiting methods, compare them, and explain how they can be used for such security applications

CGRaBS: An All-Sky Survey of Gamma-Ray Blazar Candidates

We describe a uniform all-sky survey of bright blazars, selected primarily by their flat radio spectra, that is designed to provide a large catalog of likely gamma-ray AGN. The defined sample has 1625 targets with radio and X-ray properties similar to those of the EGRET blazars, spread uniformly across the |b| > 10 deg sky. We also report progress toward optical characterization of the sample; of objects with known R < 23, 85% have been classified and 81% have measured redshifts. One goal of this program is to focus attention on the most interesting (e.g., high redshift, high luminosity, ...) sources for intensive multiwavelength study during the observations by the Large Area Telescope (LAT) on GLAST.Comment: 18 pages, 6 figures, 1 machine-readable table available at http://astro.stanford.edu/CGRaBS/ ; accepted for publication in ApJ