Search results for "Longitudinal"
showing 10 items of 1501 documents
A cohort perspective of youth poverty in the United States
2014
The aim of this paper is to study the degree of poverty persistence of American young adults and its evolution. Using data from NLSY79 and NLSY97, respectively, we compared two cohorts followed along eight years (in the 1980s and in the 2000s) to asses which socio-economic characteristics preserve them to fall in chronic poverty or determine the duration and severity of this detrimental experience.
Global dynamical behaviors in a physical shallow water system
2016
International audience; The theory of bifurcations of dynamical systems is used to investigate the behavior of travelling wave solutions in an entire family of shallow water wave equations. This family is obtained by a perturbative asymptotic expansion for unidirectional shallow water waves. According to the parameters of the system, this family can lead to different sets of known equations such as Camassa-Holm, Korteweg-de Vries, Degasperis and Procesi and several other dispersive equations of the third order. Looking for possible travelling wave solutions, we show that different phase orbits in some regions of parametric planes are similar to those obtained with the model of the pressure …
Measurement of the Depth of Maximum of Extensive Air Showers above 10(18) eV
2010
We describe the measurement of the depth of maximum, Xmax, of the longitudinal development of air showers induced by cosmic rays. Almost four thousand events above 10¹⁸ eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of (106⁺³⁵₋₂₁) g/cm²/decade below 1018.24 ± 0.05 eV and (24 ± 3) g/cm²/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm². The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.
Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory
2009
From direct observations of the longitudinal development of ultra-high energy air showers performed with the Pierre Auger Observatory, upper limits of 3.8%, 2.4%, 3.5% and 11.7% (at 95% c.l.) are obtained on the fraction of cosmic-ray photons above 2, 3, 5 and 10 EeV (1 EeV equivalent to 10(18) eV), respectively. These are the first experimental limits on ultra-high energy photons at energies below 10 EeV. The results complement previous constraints on top-down models from array data and they reduce systematic uncertainties in the interpretation of shower data in terms of primary flux, nuclear composition and proton-air cross-section.
Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory
2009
Atmospheric parameters, such as pressure (P), temperature (T) and density (ρ ∝ P/T), affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a ∼ 10% seasonal modulation and ∼ 2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of P and ρ. The former affects the longitudinal development of air showers while the latter influences the Molière radius and hence the lateral distribution of the shower particles. The model is val…
Développement des préférences sensorielles et du comportement alimentaire dans l'enfance
2013
Mémoire en vue de l’obtention de l’Habilitation à Diriger des Recherches confidentiel
Assessing short- and long-term repeatability and stability of personality in captive zebra finches using longitudinal data
2012
11 pages; International audience; Assessing behavioural consistency is crucial to understand the evolution of personality traits. In the present study, we examined the short- and long-term repeatability and stability of two unrelated personality traits - exploratory tendencies and struggling rate - using captive female zebra finches (Taeniopygia guttata). We performed two experimental sessions of behavioural tests with a 7-mo interval, which represents up to one quarter of a zebra finch's life expectancy. We showed that, overall, exploratory tendencies and struggling rate were significantly repeatable in the short term. However, only exploratory tendencies were repeatable in the long term. …
Left-Ventricle Segmentation of SPECT Images of Rats
2015
Single-photon emission computed tomography (SPECT) imaging of the heart is helpful to quantify the left-ventricular ejection fraction and study myocardial perfusion scans. However, these evaluations require a 3-D segmentation of the left-ventricular wall on each phase of the cardiac cycle. This paper presents a fast and interactive graph cut method for 3-D segmentation of the left ventricle (LV) of rats in SPECT images. The method is carried out in three steps. First, 3-D sampling of the LV cavity is made in a spherical-cylindrical coordinate system. Then, a graph-cut-based energy minimization procedure provides delineation of the myocardium centerline surface. From there, it is possible to…
Alice au Pays des NEET : la traversée du miroir sur 20 ans
2018
International audience
A l'épreuve du temps : données longitudinales et analyse de l'action publique : XXes journées d'étude sur les données longitudinales dans l'analyse d…
2013
En ligne sur : http://www.cereq.fr/index.php/content/download/7936/71610/file/Relief42.pdf; Le rapport des données longitudinales à l'action publique n'est pas une question nouvelle. Il restait à l'aborder frontalement, comme thème directeur, et c'est l'objet de cette vingtième édition des " Journées du Longitudinal " dont les contributions sont regroupées dans cet ouvrage.