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Search Results: 1 - 10 of 229694 matches for " Jo?l Mathez "
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Recensions Bibliogràfiques
Mathez, Jol,Gómez, Daniel
Collectanea Botanica , 2000,
Abstract:
Genome Size Study in the Valerianaceae: First Results and New Hypotheses
Oriane Hidalgo,Jol Mathez,Sònia Garcia,Teresa Garnatje,Jaume Pellicer,Joan Vallès
Journal of Botany , 2010, DOI: 10.1155/2010/797246
Abstract: The purpose of this study is to provide a new focus to contribute, from the perspective of genomic evolution, towards a better understanding of the Valerianaceae evolutionary history. Chromosome numbers were determined by Feulgen staining in 24 populations of 18 species (first count for Valerianella multidentata, –16), and DNA contents were assessed by flow cytometry in 74 populations of 35 species (first assessments in all taxa but Centranthus ruber). A molecular phylogeny based on the trnL-trnF and including 41 new sequences was established, with the first DNA sequence for Centranthus nevadensis, Valeriana rotundifolia, V. saxatilis, Valerianella multidentata, and V. turgida. This work is the first large genome size study devoted to the Valerianaceae, showing a range of DNA amounts from ?pg (Valerianella turgida) to ?pg (Valeriana officinalis). At the family level, changes in basic chromosome number and genome size coincide with or precede major shifts in the evolutionary history of the group, such as those concerning stamen number and floral symmetry. 1. Introduction The family Valerianaceae (currently considered within the Caprifoliaceae s.l.; [1]) comprises ca. 400 species of which approximately 200 are included in Valeriana L., the biggest genus of the order Dipsacales. The Valerianaceae are cosmopolitan in their natural distribution, with the exceptions of Australia and the Pacific islands, where they were introduced, and can be nowadays considered as naturalized. Several of their representatives have economic interest as medicinal (e.g., V. officinalis L.), edible (e.g., Valerianella Mill., corn salad or lamb’s lettuce), or ornamental plants (e.g., Centranthus DC.). The family always roused important scientific interest, and its study has broadly benefited from the new molecular techniques, especially the phylogenetic reconstructions. Recent phylogenies based on DNA sequencing [2–7] have considerably modified the traditional classification of the family [8–12]. Molecular results recognize only six genera: Centranthus, Fedia Gaertn., Nardostachys DC., Patrinia Juss., Valeriana (including Aretiastrum DC., Astrephia Dufr., Belonanthus Graebn., Phyllactis Pers., Porteria Hook., and Stangea Graebn.), and Valerianella. Plectritis (Lindl.) DC. is nested amongst South American Valeriana [5, 6]. Moreover, Bell [7] suggested a possible further taxonomic treatment of the family considering Fedia as a synonym of Valerianella. New genera may also be described for some of the Valeriana species that do not group with their congenerics in the phylogenetic
V/Vmax statistic and Neo-Classic Cosmological Tests
L. Van Waerbeke,G. Mathez,Y. Mellier,H. Bonnet,M. Lachieze-Rey
Physics , 1995,
Abstract: A new cosmological test is derived, based on the distribution of individual V/Vmax in a complete redshift-limited sample of distant objects. The fundamental assumption is that, in any bin of absolute luminosity, individual V/Vmax are required to be uniformly spread over the [0,1] range. This condition of uniformity allows a likelihood function to be computed from the Kolmogorov- Smirnov probabilities of each bin. Monte-Carlo simulations show that the test is mostly sensitive to the density parameter, but under certain conditions, it also sets constraints on the space curvature and, to a lower extent, on the cosmological constant. The test is then applied to the UVX sample of Boyle et al. (1990). A low matter density, and a flat Universe without cosmological constant, are rejected: 0.2
Pure Luminosity Evolution Hypothesis for QSOs: From Luminosity Functions to Synthetic Catalogues
G. Mathez,L. Van Waerbeke,Y. Mellier,H. Bonnet,M. Lachieze-Rey
Physics , 1995,
Abstract: This paper describes the simulation of realistic Monte-Carlo extragalactic catalogues, aimed at comparing the behaviour of cosmological tests versus input parameters. QSO catalogues are built on a Luminosity Function derived from data through suitable computation of individual maximum volumes in complete (but magnitude- and redshift-limited) samples requiring neither of redshift nor of apparent magnitude histogram. The values of the evolution parameter are derived for various cosmologies, corresponding to =1/2 in the sample of 400 Ultra-Violet Excess (UVX) QSOs (Boyle et al 1990). The various luminosity functions are compared, both for the whole sample and in redshift bins. An evolution characteristic time is defined and computed, depending strongly on the cosmology, but practically constant when expressed in terms of the age of the Universe. Algorithms are given for producing unbiased or biased catalogues based on the null hypothesis that the objects are uniformly distributed in volume but suffer Pure Luminosity Evolution.
The Auto-Correlation Function of the extragalactic background light: I. Measuring gravitational shear
L. Van Waerbeke,Y. Mellier,P. Schneider,B. Fort,G. Mathez
Physics , 1996,
Abstract: A new method for measuring the shear induced by gravitational light deflection is proposed. It is based on analyzing the anisotropy induced in the auto-correlation function (ACF) of the extragalactic background light which is produced by very faint distant galaxies. The ACF can be measured `locally', and its anisotropy is caused by the tidal gravitational field of the deflecting mass distribution in the foreground of these faint background galaxies. Since the method does not require individual galaxy detection, it can be used to measure the shear of extremely faint galaxies which are not detectable individually, but are present in the noise. The shear estimated from the ACF of the noise provides an independent measurement which can be compared to the shear obtained from the distortion of individual galaxy images. Combining these two independent estimates clearly increases the sensitivity of shear measurements. In addition, our method may allow to determine the local magnification caused by the deflector if the auto-correlation function is caused by a large number density of faint galaxies; in this case, the intrinsic ACF may provide a `standard source' with respect to which shear and magnification can be obtained. Applications to real and synthetic data are shown and the feasibility of our new method is demonstrated. In particular, we present the shear maps obtained with our method for the double QSO 2345+007 and the cluster Cl0024+16 and compare them to published shear maps.
What can we learn from VIRMOS quasars?
G. Mathez,E. Hatziminaoglou
Physics , 1998,
Abstract: Large, homogeneous quasar samples are necessary tools for the study of QSO statistics, cosmological tests, large scale structure and AGN evolution. These samples must be complete within well defined flux limits at all redshifts. An observational strategy without previous photometric selection of quasar candidates is described, based essentially on the VIRMOS Survey spectroscopy.
Management options for accidental injection of epinephrine from an autoinjector: a case report
Christian Mathez, Bernard Favrat, Philippe Staeger
Journal of Medical Case Reports , 2009, DOI: 10.4076/1752-1947-3-7268
Abstract: A physician in a Family Practice training program accidentally injected epinephrine into his left thumb while reading the operating instructions of an autoinjector (Epipen?). He developed swelling, pallor, and pain in the thumb. Treatment included topical nitroglycerin, oral vasodilators and warming of the thumb. As expected, none caused an immediate response; however, after 8 hours, the thumb was pink and warm. There was full recovery 2 months after the accident. We reviewed the treatment of accidental epinephrine injection, and found that the use of parenteral adrenergic alpha blocker phentolamine would have produced immediate recovery.All health professionals concerned with the use of epinephrine autoinjectors should receive adequate instruction on their use. A regimen for management of accidental epinephrine injection, in particular the use of phentolamine, should be emphasized.Treatment of severe anaphylaxis with epinephrine autoinjector devices such as Epipen? (or Anapen?) and Epipen Jr? has been available since 1980. Patients who have an acute allergic reaction can immediately inject epinephrine with them, reversing peripheral vasodilation, edema, constriction of the airways, and myocardial depression. However, these devices are not without risk: myocardial infarction from injected epinephrine has been reported [1]. We report a physician who accidentally injected epinephrine into his thumb while handling an autoinjector, and the results of reviewing the literature.A 31-year-old physician in a Family Practice training program at an academic primary care center was handling an Epipen? because he wanted to be familiar with it before prescribing it. While reading the operating instructions, he attempted to launch the needle but erroneously placed his left thumb over the needle opening. He accidentally discharged the contents of the spring-loaded syringe into his thumb; and the needle was twisted into the distal tip of his finger. Hand X-ray did not show a fractur
Quasar Candidate Multicolor Selection Technique: a different approach
E. Hatziminaoglou,G. Mathez,R. Pello
Physics , 2000,
Abstract: We present a quasar candidate identification technique based on multicolor photometry. The traditional multi-dimensional method (2 $\times$ N dimensions, where N is the number of the color-color diagrams) is reduced to a one-dimensional technique, which consists in a standard fitting procedure, where the observed spectral energy distributions are compared to quasar simulated spectra and stellar templates. This new multicolor approach is firstly applied to simulated catalogues and its {\it efficiency} is examined in various redshift ranges, as a function of the filter combination and the available observing time for spectroscopy. We conclude that this method is better suited than the usual multicolor selection techniques to quasar identification, especially for high-redshift quasars. The application of the method to real quasar samples found in the literature results in an {\it efficiency} comparable to the one obtained from the use of color-color diagrams. The major advantage of the new method is the estimation of the {\it photometric} redshift of quasar candidates, enabling, in almost all cases, spectroscopy to be targeted to best suited wavelength ranges.
Hierarchical Clustering and Active Galaxies
E. Hatziminaoglou,G. Mathez,A. Manrique
Physics , 2000,
Abstract: The growth of Super Massive Black Holes and the parallel development of activity in galactic nuclei are implemented in an analytic code of hierarchical clustering. The evolution of the luminosity function of quasars and AGN will be computed with special attention paid to the connection between quasars and Seyfert galaxies. One of the major interests of the model is the parallel study of quasar formation and evolution and the History of Star Formation.
The evolution rate of quasars at various redshifts
Evanthia Hatziminaoglou,Ludovic Van Waerbeke,Guy Mathez
Physics , 1998,
Abstract: The evolution of optically selected quasars is usually supposed to be well described by a single constant parameter, either k_L or k_D, depending whether we refer to luminosity or density evolution. In this paper we present a study of the variations of the evolution parameters with redshift, for different cosmological models, in order to probe the differential evolution with redshift. Two different quasar samples have been analyzed, the AAT Boyle's et al. and the LBQS catalogues. Basically, these samples are divided in redshift intervals and in each of them k_L and k_D are estimated by forcing that =0.5. The dependence with respect to the cosmological parameters is small. Both AAT and LBQS show roughly the same tendencies. LBQS, however, shows strong fluctuations, whose origin is not statistical but rather due to the selection criteria. A discussion on selection techniques, biases and binning effects explains the differences between these results. We finally conclude that the evolution parameter is almost constant in the redshift range 0.7 < z < 1.7, at least within 2 sigma, while it decreases slightly afterwards. Results depend on the binning chosen (but not in a very significant way). The method has been tested with Monte-Carlo simulated catalogues in order to give a better understanding of the results coming from the real catalogues. A correlation between k_L (k_D) and is also derived and is used for the calculation of the error bars on the evolution parameter.
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