79 research outputs found
A technique for the extraction and restriction endonuclease digestion of total DNA from Globodera rostochiensis and Globodera pallida second stage juveniles
The genome size and chromosome complement of the potato cyst nematode Globodera pallida
La taille du génome de #Globodera pallida a été estimée par microdensitométrie directe de noyaux somatiques colorés, et comparée à celle de #Caenorhabditis elegans. Elles ne se sont pas révélées significativement différentes, aussi le génome de #G. pallida est-il estimé être composé de 1 x 10 8 paires de base. Cette valeur est du même ordre que les tailles du génome déjà calculées pour d'autres espèces de nématodes. Dans les gonades disséquées, les chromosomes ont été rendus visibles par cinq techniques différentes de coloration : acide propionique/orcéine, Feulgen, Giemsa et deux colorants fluorescents, le DAPI (4'6-diamidino-2-phénylindole) et le Hoechst 33258 (Bisbenzimide). La coloration à l'aide propionique/orcéine s'est révélée la meilleure et, en dépit de la faible taille des chromosomes, a pu être utilisée pour montrer que le nombre de chromosomique de #G. pallida est égal à dix-huit (n=9). (Résumé d'auteur
Molecular diversity amongst Radopholus similis populations from Sri Lanka detected by RAPD analysis
La réaction de polymérase en chaîne (RAPD) a été utilisée pour comparer l'ADN de quatorze populations de #Radopholus similis provenant de différentes plantes hôtes et de régions variées du Sri Lanka, ainsi que l'ADN d'une nouvelle espèce de #Radopholus originaire de l'est de Java. Quatre populations isolées d'aréquier, théier, bananier et citrus semblent très différentes d'après leur profil de RAPD. L'analyse hiérarchisée des groupes des données obtenus d'après les profils de RAPD a permis un essai de regroupement des quinze populations en trois groupes et a montré l'éloignement de trois isolats demeurant jusqu'à maintenant monotypiques. Les résultats sont examinés dans le contexte de l'existence de biotypes de #R. similis$ et de leur divergence génétique au Sri Lanka. (Résumé d'auteur
Transiting Exoplanets with JWST
The era of exoplanet characterization is upon us. For a subset of exoplanets
-- the transiting planets -- physical properties can be measured, including
mass, radius, and atmosphere characteristics. Indeed, measuring the atmospheres
of a further subset of transiting planets, the hot Jupiters, is now routine
with the Spitzer Space Telescope. The James Webb Space Telescope (JWST) will
continue Spitzer's legacy with its large mirror size and precise thermal
stability. JWST is poised for the significant achievement of identifying
habitable planets around bright M through G stars--rocky planets lacking
extensive gas envelopes, with water vapor and signs of chemical disequilibrium
in their atmospheres. Favorable transiting planet systems, are, however,
anticipated to be rare and their atmosphere observations will require tens to
hundreds of hours of JWST time per planet. We review what is known about the
physical characteristics of transiting planets, summarize lessons learned from
Spitzer high-contrast exoplanet measurements, and give several examples of
potential JWST observations.Comment: 22 pages, 11 figures. In press in "Astrophysics in the Next Decade:
JWST and Concurrent Facilities, Astrophysics & Space Science Library,
Thronson, H. A., Tielens, A., Stiavelli, M., eds., Springer: Dordrecht
(2008)." The original publication will be available at
http://www.springerlink.co
The first multi-wavelength campaign of AXP 4U 0142+61 from radio to hard X-rays
For the first time a quasi-simultaneous multi-wavelength campaign has been
performed on an Anomalous X-ray Pulsar from the radio to the hard X-ray band.
4U 0142+61 was an INTEGRAL target for 1 Ms in July 2005. During these
observations it was also observed in the X-ray band with Swift and RXTE, in the
optical and NIR with Gemini North and in the radio with the WSRT. In this paper
we present the source-energy distribution. The spectral results obtained in the
individual wave bands do not connect smoothly; apparently components of
different origin contribute to the total spectrum. Remarkable is that the
INTEGRAL hard X-ray spectrum (power-law index 0.79 +/- 0.10) is now measured up
to an energy of ~230 keV with no indication of a spectral break. Extrapolation
of the INTEGRAL power-law spectrum to lower energies passes orders of magnitude
underneath the NIR and optical fluxes, as well as the low ~30 microJy (2 sigma)
upper limit in the radio band.Comment: 6 pages, 1 figure. To be published in the proceedings of the
conference "Isolated Neutron Stars: from the Interior to the Surface" (April
24-28, 2006, London, UK), eds. S. Zane, R. Turolla and D. Pag
On gravitational waves emitted by an ensemble of rotating neutron stars
We study the possibility to detect the gravitational wave background
generated by all the neutron stars in the Galaxy with only one gravitational
wave interferometric detector. The proposed strategy consists in squaring the
detector's output and searching for a sidereal modulation. The shape of the
squared signal is computed for a disk and a halo distribution of neutron stars.
The required noise stability of the interferometric detector is discussed. We
argue that a possible population of old neutron stars, originating from a high
stellar formation rate at the birth of the Galaxy and not emitting as radio
pulsars, could be detected by the proposed technique in the low frequency range
of interferometric experiments.Comment: 14 pages, 2 PostScript figures, RevTeX, accepted for publication in
Physical Review
A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007
We present the results of the first search for gravitational wave bursts
associated with high energy neutrinos. Together, these messengers could reveal
new, hidden sources that are not observed by conventional photon astronomy,
particularly at high energy. Our search uses neutrinos detected by the
underwater neutrino telescope ANTARES in its 5 line configuration during the
period January - September 2007, which coincided with the fifth and first
science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed
for candidate gravitational-wave signals coincident in time and direction with
the neutrino events. No significant coincident events were observed. We place
limits on the density of joint high energy neutrino - gravitational wave
emission events in the local universe, and compare them with densities of
merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at
http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access
area to figures, tables at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000
STRIDER (Sildenafil TheRapy in dismal prognosis early onset fetal growth restriction): An international consortium of randomised placebo-controlled trials
Background: Severe, early-onset fetal growth restriction due to placental insufficiency is associated with a high risk of perinatal mortality and morbidity with long-lasting sequelae. Placental insufficiency is the result of abnormal formation and function of the placenta with inadequate remodelling of the maternal spiral arteries. There is currently no effective therapy available. Some evidence suggests sildenafil citrate may improve uteroplacental blood flow, fetal growth, and meaningful infant outcomes. The objective of the Sildenafil TheRapy In Dismal prognosis Early onset fetal growth Restriction (STRIDER) collaboration is to evaluate the effectiveness of sildenafil versus placebo in achieving healthy perinatal survival through the conduct of randomised clinical trials and systematic review including individual patient data meta-analysis. Methods: Five national/bi-national multicentre randomised placebo-controlled trials have been launched. Women with a singleton pregnancy between 18 and 30 weeks with severe fetal growth restriction of likely placental origin, and where the likelihood of perinatal death/severe morbidity is estimated to be significant are included. Participants will receive either sildenafil 25 mg or matching placebo tablets orally three times daily from recruitment to 32 weeks gestation. Discussion: The STRIDER trials were conceived and designed through international collaboration. Although the individual trials have different primary outcomes for reasons of sample size and feasibility, all trials will collect a standard set of outcomes including survival without severe neonatal morbidity at time of hospital discharge. This is a summary of all the STRIDER trial protocols and provides an example of a prospectively planned international clinical research collaboration. All five individual trials will contribute to a pre-planned systematic review of the topic including individual patient data meta-analysis
- …