2,821 research outputs found
On-farm assessment of clonal introduction of root crops diversity in Vanuatu, Melanesia
Ex-situ collections of vegetatively propagated root crops are difficult to maintain in developing countries. On-farmconservation could be a solution but is more complex for vegetatively propagated than for sexually propagated species. In Vanuatu, a Melanesian archipelago where yam, taro, sweet potato and cassava are staples, a study was undertaken to develop an on-farm conservation system based on the geographic distribution of allelic diversity. Two years after the introduction of new varieties, a survey was conducted with 449 farmers located on 10 different islands. In order to evaluate on-farm conservation efficiency, qualitative and quantitative investigations were conducted and data were analysed. The conclusion was that farmers do enrich their varietal portfolioswith introduced exotic genotypes thus broadening the narrow genetic bases of some species. Nevertheless, no local varieties were lost. Significant geographic distribution of clones of new varieties throughout the archipelago also took place via spontaneous, informal distribution to farmers' relatives. These encouraging results point to the potential impact of the geographic distribution of allelic diversity on smallholders' varietal portfolios. On-farm conservation appears to be an appropriate strategy for the conservation of root crop germplasm diversity inVanuatu. Potential applications for transfer of the methodology to other locations are discussed. (Résumé d'auteur
Soutiens perçus, engagements affectifs et succès de carrière subjectif : une approche en termes de profils
Perceived support, affective commitments and subjective career success: a person-centred approach (Soutiens perçus, engagements affectifs et succès de carrière subjectif : une approche en termes de profils)
Polarization-dependence of anomalous scattering in brominated DNA and RNA molecules, and importance of crystal orientation in single- and multiple-wavelength anomalous diffraction phasing
In this paper the anisotropy of anomalous scattering at the Br K-absorption edge in brominated nucleotides is investigated, and it is shown that this effect can give rise to a marked directional dependence of the anomalous signal strength in X-ray diffraction data. This implies that choosing the correct orientation for crystals of such molecules can be a crucial determinant of success or failure when using single- and multiple-wavelength anomalous diffraction (SAD or MAD) methods to solve their structure. In particular, polarized absorption spectra on an oriented crystal of a brominated DNA molecule were measured, and were used to determine the orientation that yields a maximum anomalous signal in the diffraction data. Out of several SAD data sets, only those collected at or near that optimal orientation allowed interpretable electron density maps to be obtained. The findings of this study have implications for instrumental choices in experimental stations at synchrotron beamlines, as well as for the development of data collection strategy programs
[C II] 158 μm Emission as a Star Formation Tracer
The [C II] 157.74 μm transition is the dominant coolant of the neutral interstellar gas, and has great potential as a star formation rate (SFR) tracer. Using the Herschel KINGFISH sample of 46 nearby galaxies, we investigate the relation of [C II] surface brightness and luminosity with SFR. We conclude that [C II] can be used for measurements of SFR on both global and kiloparsec scales in normal star-forming galaxies in the absence of strong active galactic nuclei (AGNs). The uncertainty of the Σ_([C II]) – Σ_(SFR) calibration is ±0.21 dex. The main source of scatter in the correlation is associated with regions that exhibit warm IR colors, and we provide an adjustment based on IR color that reduces the scatter. We show that the color-adjusted Σ_([C II]) – Σ_(SFR) correlation is valid over almost five orders of magnitude in Σ_(SFR), holding for both normal star-forming galaxies and non-AGN luminous infrared galaxies. Using [C II] luminosity instead of surface brightness to estimate SFR suffers from worse systematics, frequently underpredicting SFR in luminous infrared galaxies even after IR color adjustment (although this depends on the SFR measure employed). We suspect that surface brightness relations are better behaved than the luminosity relations because the former are more closely related to the local far-UV field strength, most likely the main parameter controlling the efficiency of the conversion of far-UV radiation into gas heating. A simple model based on Starburst99 population-synthesis code to connect SFR to [C II] finds that heating efficiencies are 1%-3% in normal galaxies
Quelques aspects de la pathologie des petits ruminants en Guadeloupe et en Martinique
Quelques résultats préliminaires provenant de diagnostics de laboratoire et d'enquêtes apportent les indications suivantes : la coccidiose joue vraisemblablement un rôle important dans le parasitisme gastro-intestinal des petits ruminants, jeunes et adultes; la toxoplasmose et la fièvre Q interviennent dans les avortements et les mortinatalités; si la dermatophilose des chèvres ne provoque que des lésions localisées en Guadeloupe, celle des moutons revêt un caractère extensif et mortel en Martinique; la fièvre catarrhale existe en Guadeloupe mais son impact n'est pas connu, ni celui de l'anaplasmose. Par contre la trypanosomose a disparu de Guadeloupe et de Martiniqu
CCAT-prime: Science with an Ultra-widefield Submillimeter Observatory at Cerro Chajnantor
We present the detailed science case, and brief descriptions of the telescope
design, site, and first light instrument plans for a new ultra-wide field
submillimeter observatory, CCAT-prime, that we are constructing at a 5600 m
elevation site on Cerro Chajnantor in northern Chile. Our science goals are to
study star and galaxy formation from the epoch of reionization to the present,
investigate the growth of structure in the Universe, improve the precision of
B-mode CMB measurements, and investigate the interstellar medium and star
formation in the Galaxy and nearby galaxies through spectroscopic,
polarimetric, and broadband surveys at wavelengths from 200 um to 2 mm. These
goals are realized with our two first light instruments, a large field-of-view
(FoV) bolometer-based imager called Prime-Cam (that has both camera and an
imaging spectrometer modules), and a multi-beam submillimeter heterodyne
spectrometer, CHAI. CCAT-prime will have very high surface accuracy and very
low system emissivity, so that combined with its wide FoV at the unsurpassed
CCAT site our telescope/instrumentation combination is ideally suited to pursue
this science. The CCAT-prime telescope is being designed and built by Vertex
Antennentechnik GmbH. We expect to achieve first light in the spring of 2021.Comment: Presented at SPIE Millimeter, Submillimeter, and Far-Infrared
Detectors and Instrumentation for Astronomy IX, June 14th, 201
Le bovin créole en Guadeloupe : Caractéristiques et performances zootechniques
Ce travail décrit les principales caractéristiques zootechniques du bovin Créole. Appartenant, dans la plupart des cas, au genre Bos indicus, cette race de petit format, résistante aux températures élevées comme aux pathologies parasitaires et infectieuses locales, se montre bien adaptée au milieu tropical. La fertilité des femelles est bonne et n'est pas influencée par l'environnement thermique. Bien que la croissance des produits soit faible, et leur conformation médiocre, leur rendement de carcasse est intéressant. Ces animaux peuvent donc aisément constituer la base d'un troupeau de production de viande dans des conditions difficiles et avec un système d'élevage de type extensi
Recommended from our members
Impact of particles on the Planck HFI detectors: Ground-based measurements and physical interpretation
The Planck High Frequency Instrument (HFI) surveyed the sky continuously from
August 2009 to January 2012. Its noise and sensitivity performance were
excellent, but the rate of cosmic ray impacts on the HFI detectors was
unexpectedly high. Furthermore, collisions of cosmic rays with the focal plane
produced transient signals in the data (glitches) with a wide range of
characteristics. A study of cosmic ray impacts on the HFI detector modules has
been undertaken to categorize and characterize the glitches, to correct the HFI
time-ordered data, and understand the residual effects on Planck maps and data
products. This paper presents an evaluation of the physical origins of glitches
observed by the HFI detectors. In order to better understand the glitches
observed by HFI in flight, several ground-based experiments were conducted with
flight-spare HFI bolometer modules. The experiments were conducted between 2010
and 2013 with HFI test bolometers in different configurations using varying
particles and impact energies. The bolometer modules were exposed to 23 MeV
protons from the Orsay IPN TANDEM accelerator, and to Am and Cm
-particle and Fe radioactive X-ray sources. The calibration data
from the HFI ground-based preflight tests were used to further characterize the
glitches and compare glitch rates with statistical expectations under
laboratory conditions. Test results provide strong evidence that the dominant
family of glitches observed in flight are due to cosmic ray absorption by the
silicon die substrate on which the HFI detectors reside. Glitch energy is
propagated to the thermistor by ballistic phonons, while there is also a
thermal diffusion contribution. The implications of these results for future
satellite missions, especially those in the far-infrared to sub-millimetre and
millimetre regions of the electromagnetic spectrum, are discussed.Comment: 11 pages, 13 figure
- …
