459 research outputs found
Hydrologie et géochimie isotopique
Cet ouvrage rassemble des travaux rĂ©cents dans les domaines de l'hydrologie et de la gĂ©ochimie isotopique. La premiĂšre partie explore le cycle des eaux naturelles, depuis les prĂ©cipitations jusqu'aux aquifĂšres profonds, par l'analyse des variations de la composition isotopique de l'hydrogĂšne, de l'oxygĂšne et du carbone. Des types rĂ©gionaux sont prĂ©sentĂ©s, sous diverses latitudes : Spitzberg, Bassin parisien, bassin soudano-sahĂ©lien du Niger. L'intĂ©rĂȘt de l'approche isotopique dans l'Ă©tude du changement global est illustrĂ©e en deuxiĂšme partie. Les variations hydro-climatiques de types rĂ©gionaux, en Afrique essentiellement, sont retracĂ©es par l'analyse multidisciplinaire d'enregistrements sĂ©dimentaires, dont la gĂ©ochimie isotopique constitue la clĂ© essentielle. L'homogĂ©nĂ©itĂ© du refroidissement, aux moyennes et basses latitudes, lors du dernier maximum glaciaire est dĂ©montrĂ©e par l'analyse isotopique des gaz nobles dans les eaux souterraines. La mise en Ă©vidence de l'origine organique du carbone de carbonates sĂ©dimentaires remet en question l'interprĂ©tation de certaines analyses isotopiques. La troisiĂšme partie fait rĂ©fĂ©rence aux isotopes d'origine cosmique et Ă la production in situ de radionuclĂ©ides. Il est rappelĂ© que la datation par 14C a contribuĂ© Ă la comprĂ©hension des mĂ©canismes des changements du climat au cours du dernier maximum glaciaire et depuis lors. Les limites de cette mĂ©thode et ses progrĂšs rĂ©cents font l'objet d'une synthĂšse amplement documentĂ©e. Par l'apport de donnĂ©es isotopiques, la gĂ©ochimie s'avĂšre fonder la modĂ©lisation des conditions de stabilitĂ© du rĂ©acteur de fission nuclĂ©aire fossile d'Oklo. (RĂ©sumĂ© d'auteur
Cryptic diversity within the major trypanosomiasis vector Glossina fuscipes revealed by molecular markers
Background: The tsetse fly Glossina fuscipes s.l. is responsible for the transmission of approximately 90% of cases of human African trypanosomiasis (HAT) or sleeping sickness. Three G. fuscipes subspecies have been described, primarily based upon subtle differences in the morphology of their genitalia. Here we describe a study conducted across the range of this important vector to determine whether molecular evidence generated from nuclear DNA (microsatellites and gene sequence information), mitochondrial DNA and symbiont DNA support the existence of these taxa as discrete taxonomic units.
Principal Findings: The nuclear ribosomal Internal transcribed spacer 1 (ITS1) provided support for the three subspecies. However nuclear and mitochondrial sequence data did not support the monophyly of the morphological subspecies G. f.fuscipes or G. f. quanzensis. Instead, the most strongly supported monophyletic group was comprised of flies sampled fromEthiopia. Maternally inherited loci (mtDNA and symbiont) also suggested monophyly of a group from Lake Victoria basin and Tanzania, but this group was not supported by nuclear loci, suggesting different histories of these markers. Microsatellite data confirmed strong structuring across the range of G. fuscipes s.l., and was useful for deriving the interrelationship of closely related populations.
Conclusion/Significance: We propose that the morphological classification alone is not used to classify populations of G. fuscipes for control purposes. The Ethiopian population, which is scheduled to be the target of a sterile insect release (SIT) programme, was notably discrete. From a programmatic perspective this may be both positive, given that it may reflect limited migration into the area or negative if the high levels of differentiation are also reflected in reproductive isolation between this population and the flies to be used in the release programme
The high burden of hospitalizations for primary EBV infection: a 6-year prospective survey in a French hospital
AbstractPrimary Epstein-Barr virus infection (PEI) is acquired increasingly later in life in developed countries, involving a growing number of adults. No studies have examined the effect of age on PEI. We conducted a prospective, single-centre, noninterventional survey to assess the clinical and economic effects of PEI care according to age. We included all serology-confirmed cases observed in all departments of a large regional hospital. Clinical and biologic data, therapeutics and costs of care were examined. Over a 6-year period, we included 292 subjects (148 children and 144 adults) with a median age of 15.4 years (range 9 months to 79 years). Adults were hospitalized more often (83% vs. 60%) and for longer periods of time (median 4 days vs. 2 days) than children (p â€Â 0.0001 for both). Two adults required a secondary transfer into the intensive care unit, although no children did. Typically, adults showed higher levels of activated lymphocytes and liver abnormalities. They also required the use of systemic corticosteroids more often (45% vs. 23%, p < 0.0001) and for longer periods of time (median 7 days vs. 3 days, p 0.02) than children. Overall, the costs were significantly higher for adults than for children (median, âŹ1940 vs. âŹ1130, p < 0.0001), mainly because of the frequency and duration of hospitalizations. Age increases the immune response and clinical severity of PEI, resulting in substantial additional costs for the community. Better recognition of the disease in adults could shorten the average length of hospital stay
Treatment of chronic hepatitis C in patients unresponsive to interferon. Interest of re-treatment combining interferon induction therapy and ribavirin (a multicenter pilot study)
Aim
About 45% of patients with chronic hepatitis C are unresponsive to the present reference treatment combining pegelated interferon plus ribavirin; before pegylated interferon was available the non-response rate was around 60%. This open multicenter pilot study, initiated before pegylated interferon became available, was designed to evaluate, in patients unresponsive to interferon monotherapy, the rate of biological and virological response and side-effects of the ribivirin- alpha 2b interferon combination.
Methods
The combination protocol was ribavirin (1 to 1.2Â g/d) plus alpha 2b interferon at induction doses (9 MU/d the first week; 4.5Â MU/d the eleven following weeks; 3Â MU/2 days the 36 following weeks).
Results
Among the 27 included patients, 17 (63%) were viremia-negative (PCR) after 12Â weeks of treatment, 9 (33%) were complete responders (undetectable viremia and normal transaminases) at the end of treatment (48Â weeks) and of follow-up (72Â weeks). Patients with non-1, non-4 genotypes who derived full benefit from this therapeutic strategy (6/7 (86%) were complete responders: 4/5 with genotype 3 and 2/2 with genotype 5). Quality-of-life was impaired during treatment, especially during the first 12Â weeks of high-dose interferon therapy.
Conclusion
While waiting for new therapeutic possibilities, these good results suggest interferon induction at the beginning of treatment remains a valid option
The Minimal Supersymmetric Standard Model: Group Summary Report
CONTENTS: 1. Synopsis, 2. The MSSM Spectrum, 3. The Physical Parameters, 4.
Higgs Boson Production and Decays, 5. SUSY Particle Production and Decays, 6.
Experimental Bounds on SUSY Particle Masses, 7. References.Comment: 121 pages, latex + epsfig, graphicx, axodraw, Report of the MSSM
working group for the Workshop "GDR-Supersym\'etrie",France. Rep. PM/98-4
New Source of CP violation in B physics ?
In this talk we discuss how the down type left-right squark mixing in
Supersymmetry can induce a new source of CP violation in the time dependent
asymmtries in B --> phi K process. We use QCD improved factorization process to
calculate the hadronic matrix element for the process and find the allowed
parameter space for and , the magnitude and phase of the down
type LR(RL) squark mixing parameter . In the same allowed
regin we calculate the expected CP asymmtries in the
process.Comment: 16 pages, Latex, 2 postscript figures, invited talk presented by N.G.
Deshpande at the 9th Adriatic meeting, Dubrovnik, Croatia, 4-14 September,
2003. With updated reference
Monitoring Cognitive and Emotional Processes Through Pupil and Cardiac Response During Dynamic Versus Logical Task
The paper deals with the links between physiological measurements and cognitive and emotional functioning. As long as the operator is a key agent in charge of complex systems, the definition of metrics able to predict his performance is a great challenge. The measurement of the physiological state is a very promising way but a very acute comprehension is required; in particular few studies compare autonomous nervous system reactivity according to specific cognitive processes during task performance and task related psychological stress is often ignored. We compared physiological parameters recorded on 24 healthy subjects facing two neuropsychological tasks: a dynamic task that require problem solving in a world that continually evolves over time and a logical task representative of cognitive processes performed by operators facing everyday problem solving. Results showed that the mean pupil diameter change was higher during the dynamic task; conversely, the heart rate was more elevated during the logical task. Finally, the systolic blood pressure seemed to be strongly sensitive to psychological stress. A better taking into account of the precise influence of a given cognitive activity and both workload and related task-induced psychological stress during task performance is a promising way to better monitor operators in complex working situations to detect mental overload or pejorative stress factor of error
D-brane anti-D-brane effective action and brane interaction in open string channel
We construct the effective action of a -brane-anti--brane system by
making use of the non-abelian extension of tachyonic DBI action. We succeed the
construction by restricting the Chan-Paton factors of two non-BPS -branes
in the action to the Chan-Paton factors of a system. For the
special case that both branes are coincident, the action reduces to the one
proposed by A. Sen. \\The effective potential indicates that
when branes separation is larger than the string length scale, there are two
minima in the tachyon direction. As branes move toward each other under the
gravitational force, the tachyon tunneling from false to true vacuum may make a
bubble formation followed by a classical evolution of the bubble. On the other
hand, when branes separation is smaller than the string length scale, the
potential shows one maximum and one minimum. In this case, a homogeneous
tachyon rolling in real time makes an attractive potential for the branes
distance. This classical force is speculated to be the effective force between
the two branes.Comment: Latex, 14 pages, 1 figure, the version appears in JHE
The Genetic Basis of Heterosis: Multiparental Quantitative Trait Loci Mapping Reveals Contrasted Levels of Apparent Overdominance Among Traits of Agronomical Interest in Maize (Zea mays L.)
Understanding the genetic bases underlying heterosis is a major issue in maize (Zea mays L.). We extended the North Carolina design III (NCIII) by using three populations of recombinant inbred lines derived from three parental lines belonging to different heterotic pools, crossed with each parental line to obtain nine families of hybrids. A total of 1253 hybrids were evaluated for grain moisture, silking date, plant height, and grain yield. Quantitative trait loci (QTL) mapping was carried out on the six families obtained from crosses to parental lines following the âclassicalâ NCIII method and with a multiparental connected model on the global design, adding the three families obtained from crosses to the nonparental line. Results of the QTL detection highlighted that most of the QTL detected for grain yield displayed apparent overdominance effects and limited differences between heterozygous genotypes, whereas for grain moisture predominance of additive effects was observed. For plant height and silking date results were intermediate. Except for grain yield, most of the QTL identified showed significant additive-by-additive epistatic interactions. High correlation observed between heterosis and the heterozygosity of hybrids at markers confirms the complex genetic basis and the role of dominance in heterosis. An important proportion of QTL detected were located close to the centromeres. We hypothesized that the lower recombination in these regions favors the detection of (i) linked QTL in repulsion phase, leading to apparent overdominance for heterotic traits and (ii) linked QTL in coupling phase, reinforcing apparent additive effects of linked QTL for the other traits
Expression of ADP-Glucose Pyrophosphorylase in Maize (Zea mays L.) Grain and Source Leaf during Grain Filling
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