Search results for "aves"
showing 10 items of 2443 documents
Lawvere–Tierney sheaves in Algebraic Set Theory
2009
We present a solution to the problem of defining a counterpart in Algebraic Set Theory of the construction of internal sheaves in Topos Theory. Our approach is general in that we consider sheaves as determined by Lawvere-Tierney coverages, rather than by Grothendieck coverages, and assume only a weakening of the axioms for small maps originally introduced by Joyal and Moerdijk, thus subsuming the existing topos-theoretic results.
Ondes scélérates et statistiques extrêmes dans les systèmes optiques fibrés
2011
This thesis deals with extremes statistics which has become an attractive subject in optics since a comparison with oceanic rogue waves has been proposed at the end of 2007. We report some potential mechanisms stimulating the rogue wave formation in the context of guided propagation of light in optical fibers. In a first part, we explore optical rogue waves in supercontinuums generated by fourth-order modulation instability and we propose a stabilization method based on the use of two continuous seeds. Then, we present a detailed study on Raman fiber amplifiers where we determine the conditions of emergence of giant structures : in presence of a partially incoherent pumping wave, a quasi-in…
Beneficial impact of wave-breaking for coherent continuum formation in normally dispersive nonlinear fibers
2008
International audience; We study the evolution of a pulse propagating in a normally dispersive fiber in the presence of Kerr nonlinearity. We review the temporal and spectral impact of optical wave-breaking in the development of a continuum. The impact of linear losses or gain is also investigated.
Fourier integral operators and inhomogeneous Gevrey classes
1988
Fourier integral operators with inhomogeneous amplitude and phase junction are studied in the frame of Gevrey classes. Applications are given to propagation of singularities for a pseudodifferential equation.
Nonresonant dielectric hole burning spectroscopy of supercooled liquids
1997
The nonexponential response of propylene carbonate and glycerol near their glass transitions could be selectively altered using nonresonant spectral hole burning (NSHB) experiments. This observation provides evidence of the existence of a distribution of relaxation times in these supercooled liquids. NSHB is based on a pump, wait, and probe scheme and uses low-frequency large amplitude electrical fields to modify the dielectric relaxation. The temporal evolution of the polarization of the sample is then measured subsequent to a small voltage step. By variation of a recovery time inserted between pump and probe, the refilling of the spectral features could be monitored and was found to take …
Comprehensive analysis of airborne pesticides using hard cap espresso extraction-liquid chromatography-high-resolution mass spectrometry
2017
A hard cap espresso extraction procedure has been developed to recover airborne pesticides in particulate matter trapped in filters. This extraction step was made for 20s at 72°C and 19bar using 50mL of 20% (v/v) acetonitrile in water. After that, based on NaCl salting out, extracts were concentrated 22 times and analysed by ultra-high performance liquid chromatography - high resolution mass spectrometry. 35 pesticides were evaluated, as a proof of concept, being validated the whole methodology and compared the extraction method with that based on microwave assisted extraction for 20min. In short, the method avoids cross-contamination of samples, it is relatively fast and consumes only 10mL…
Trace elemental composition of curry by inductively coupled plasma optical emission spectrometry (ICP-OES)
2008
A methodology based on inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted acid digestion was developed to determine the content of traces elements in curry samples from the Spanish market. The methodology was validated in terms of accuracy by the analysis of citrus and tomato leaf reference materials achieving comparable results with the certified values. The trace metal content of curry samples was compared with data available from previously published reports concerning Indian samples, especially in terms of heavy metal composition, in order to guarantee the quality of the commercially available spices in the European countries. Values found for th…
Uncinaria hamiltoni (Nematoda: Ancylostomatidae) in South American Sea Lions, Otaria flavescens, From Northern Patagonia, Argentina
2004
Thirty-one South American sea lion pups (Otaria flavescens) found dead in Punta León, Argentina, during the summer of 2002, were examined for hookworms (Uncinaria hamiltoni). Parasite parameters were analyzed in 2 locations of the rookery, i.e., a traditional, well-structured breeding area and an expanding area with juveniles and a lax social structure. Prevalence of hookworms was 50% in both localities, and no difference was observed in prevalence between pup sexes (P > 0.05). Hookworms were concentrated in the small intestine. Transmammary transmission is assumed because only adult hookworms were found in the pups. The mean intensity of hookworms per pup was 135; the mean intensity in fem…
Characteristics of the early flight phase in the Olympic ski jumping competition.
2004
Early flight phase (approximately 40 m) of the athletes participating in the final round of the individual large hill ski jumping competition in Salt Lake City Olympics was filmed with two high-speed pan & tilt video cameras. The results showed that jumpers' steady flight position was almost completed within 0.5s. The most significant correlation with the length of the jump was found in the angle between the skis and body (r=.714, p.001 at 1.1s after the take-off). This particular phase seemed to be important because the ski angle of attack was also related to the jumping distance at the same phase. Although the more upright ski position relative to flight path resulted in longer jumping di…
Relativistic simulations of rotational core collapse : I. Methods, initial models, and code tests
2002
We describe an axisymmetric general relativistic code for rotational core collapse. The code evolves the coupled system of metric and fluid equations using the ADM 3+1 formalism and a conformally flat metric approximation of the Einstein equations. The relativistic hydrodynamics equations are formulated as a first-order flux-conservative hyperbolic system and are integrated using high-resolution shock-capturing schemes based on Riemann solvers. We assess the quality of the conformally flat metric approximation for relativistic core collapse and present a comprehensive set of tests which the code successfully passed. The tests include relativistic shock tubes, the preservation of the rotatio…