188 research outputs found
Implications for compressed sensing of a new sampling theorem on the sphere
A sampling theorem on the sphere has been developed recently, requiring half
as many samples as alternative equiangular sampling theorems on the sphere. A
reduction by a factor of two in the number of samples required to represent a
band-limited signal on the sphere exactly has important implications for
compressed sensing, both in terms of the dimensionality and sparsity of
signals. We illustrate the impact of this property with an inpainting problem
on the sphere, where we show the superior reconstruction performance when
adopting the new sampling theorem compared to the alternative.Comment: 1 page, 2 figures, Signal Processing with Adaptive Sparse Structured
Representations (SPARS) 201
Sparse image reconstruction on the sphere: implications of a new sampling theorem
We study the impact of sampling theorems on the fidelity of sparse image
reconstruction on the sphere. We discuss how a reduction in the number of
samples required to represent all information content of a band-limited signal
acts to improve the fidelity of sparse image reconstruction, through both the
dimensionality and sparsity of signals. To demonstrate this result we consider
a simple inpainting problem on the sphere and consider images sparse in the
magnitude of their gradient. We develop a framework for total variation (TV)
inpainting on the sphere, including fast methods to render the inpainting
problem computationally feasible at high-resolution. Recently a new sampling
theorem on the sphere was developed, reducing the required number of samples by
a factor of two for equiangular sampling schemes. Through numerical simulations
we verify the enhanced fidelity of sparse image reconstruction due to the more
efficient sampling of the sphere provided by the new sampling theorem.Comment: 11 pages, 5 figure
Coping with multiple adversities: Men who sought medico-legal care because of physical violence from a partner or ex-partner.
Objectives: To describe male victims of physical violence by an intimate partner who consulted a medico-legal unit, and information available on their perpetrators; to characterize the violent events and their contexts. Little research exists on male victims of physical intimate partner violence seeking medical care. Method: Based on Heise’s ecological framework, mixed methods were used to analyze quantitative and qualitative data collected during 122 medico-legal consultations attended by 115 men who sustained physical violence by an intimate partner from 2006–2012. Results: Quantitative and quantitative data collected from male victims concurred in showing that many of such victims, as well as their partners, faced at the time of the assault multiple adversities and challenges at individual and relationship levels. Among male victims, 26% had no paid job. Among perpetrators, 34% were third-country nationals subject to restricted residence permits. Health issues, worries about money or work combined with complex and conflictive family situations were often in the background of violent events. In a few cases, however, male victims reported no other problems than their partner’s assault. Conclusions: Our findings point out gender-specific aspects of female-to-male physical partner violence. The most common feature is that violence was experienced as one among several adversities. Even though wounds sustained by male victims were not necessarily severe, their emotional suffering was frequent. When underage children were involved, their situation was particularly noteworthy. Interventions with male victims of intimate partner violence should include protection of minors as a priority and as an incentive for fathers to seek help
La prévention et le sexting : un état des lieux
Le développement social et relationnel des adolescent-e-s et des jeunes adultes s’effectue aujourd’hui avec celui d’Internet et des nouvelles technologies. Dans ce contexte, les interactions et la transmission d’informations numériques sont facilitées et peu restreintes, ce qui peut mener à un certain nombre d’enjeux en termes d’usage des technologies et de gestion de l’image numérique. Le sexting fait partie de ces problématiques. Cette pratique pouvant, de manière générale, se définir comme l’échange électronique de matériel personnel à caractère sexuel ou intime, peut parfois mener à des situations dramatiques lorsque, par exemple, le contenu d’un message est transféré sans consentement à d’autres personnes.
Après avoir mené une première recherche exploratoire qualitative sur la pratique du sexting chez les jeunes, la thématique de la prévention relative au sexting s’est avérée particulièrement intéressante à approfondir. En effet, très peu de jeunes ont rapporté se rappeler de messages ou campagnes de prévention autour du sexting spécifiquement. Au vu de ces résultats, nous avons considéré qu’il était essentiel d’établir un état des lieux de l’offre préventive sur la thématique du sexting, plus particulièrement dans le canton de Vaud, afin de vérifier les dires de certains jeunes sur le manque d’intervention et de discussion sur le sexting et ses possibles dérives.
A travers cet état des lieux et ce rapport, nous proposons donc un catalogue permettant de répertorier et d’offrir une vue d’ensemble des différents acteurs-trices et ressources à disposition dans le cadre de la prévention relative à la pratique du sexting auprès des jeunes
Limits on decaying dark energy density models from the CMB temperature-redshift relation
The nature of the dark energy is still a mystery and several models have been
proposed to explain it. Here we consider a phenomenological model for dark
energy decay into photons and particles as proposed by Lima (J. Lima, Phys.
Rev. D 54, 2571 (1996)). He studied the thermodynamic aspects of decaying dark
energy models in particular in the case of a continuous photon creation and/or
disruption. Following his approach, we derive a temperature redshift relation
for the CMB which depends on the effective equation of state and on
the "adiabatic index" . Comparing our relation with the data on the CMB
temperature as a function of the redshift obtained from Sunyaev-Zel'dovich
observations and at higher redshift from quasar absorption line spectra, we
find , adopting for the adiabatic index ,
in good agreement with current estimates and still compatible with
, implying that the dark energy content being constant in time.Comment: 8 pages, 1 figur
The first spectral line surveys searching for signals from the Dark Ages
Our aim is to observationally investigate the cosmic Dark Ages in order to
constrain star and structure formation models, as well as the chemical
evolution in the early Universe. Spectral lines from atoms and molecules in
primordial perturbations at high redshifts can give information about the
conditions in the early universe before and during the formation of the first
stars in addition to the epoch of reionisation. The lines may arise from moving
primordial perturbations before the formation of the first stars (resonant
scattering lines), or could be thermal absorption or emission lines at lower
redshifts. The difficulties in these searches are that the source redshift and
evolutionary state, as well as molecular species and transition are unknown,
which implies that an observed line can fall within a wide range of
frequencies. The lines are also expected to be very weak. Observations from
space have the advantages of stability and the lack of atmospheric features
which is important in such observations. We have therefore, as a first step in
our searches, used the Odin satellite to perform two sets of spectral line
surveys towards several positions. The first survey covered the band 547-578
GHz towards two positions, and the second one covered the bands 542.0-547.5 GHz
and 486.5-492.0 GHz towards six positions selected to test different sizes of
the primordial clouds. Two deep searches centred at 543.250 and 543.100 GHz
with 1 GHz bandwidth were also performed towards one position. The two lowest
rotational transitions of H2 will be redshifted to these frequencies from
z~20-30, which is the predicted epoch of the first star formation. No lines are
detected at an rms level of 14-90 and 5-35 mK for the two surveys,
respectively, and 2-7 mK in the deep searches with a channel spacing of 1-16
MHz. The broad bandwidth covered allows a wide range of redshifts to be
explored for a number of atomic and molecular species and transitions. From the
theoretical side, our sensitivity analysis show that the largest possible
amplitudes of the resonant lines are about 1 mK at frequencies <200 GHz, and a
few micro K around 500-600 GHz, assuming optically thick lines and no
beam-dilution. However, if existing, thermal absorption lines have the
potential to be orders of magnitude stronger than the resonant lines. We make a
simple estimation of the sizes and masses of the primordial perturbations at
their turn-around epochs, which previously has been identified as the most
favourable epoch for a detection. This work may be considered as an important
pilot study for our forthcoming observations with the Herschel Space
Observatory.Comment: 15 pages, 9 figures, 3 on-line pages. Accepted for publication in
Astronomy & Astrophysics 8 March 2010
Enfants exposés à la violence dans le couple parental : étude rétrospective des données récoltées auprès de 430 mères et pères de 654 enfants âgés de 0 à 17 ans, lorsque ces parents avaient consulté l’Unité de médecine des violences du CHUV suite à un événement violent dans le couple survenu entre 2011 et 2014
[Préface (extraits)] L'étude menée par l'équipe de l'Unité de médecine des violences (UMV) entrouvre la porte de la chambre des enfants, afin d’amener un éclairage supplémentaire sur la nature et les circonstances de l’exposition des enfants à la violence dans le couple parental. Elle montre comment les enfants sont directement concernés dans la violence qui a lieu dans leur foyer. Souvent atteints psychiquement et physiquement, il n'est pas rare qu'ils aillent jusqu’à s'interposer au milieu de ces rapports de violence en se mettant eux-mêmes en danger lorsqu’ils prennent la défense de la victime, le plus souvent d'ailleurs leur mère. Dans d'autres cas, ils et elles intériorisent les modèles genrés d'auteur ou de victime auprès desquels ils grandissent et puisent leur identité. Les prérequis favorables à une transmission intergénérationnelle de la violence dans le couple sont renforcés par cette immersion quotidienne
How small were the first cosmological objects?
The minimum mass that a virialized gas cloud must have in order to be able to
cool in a Hubble time is computed, using a detailed treatment of the chemistry
of molecular hydrogen. With a simple model for halo profiles, we reduce the
problem to that of numerically integrating a system of chemical equations. The
results agree well with numerically expensive 3D simulations, and our approach
has the advantage of rapidly being able to explore large regions of parameter
space. The minimum baryonic mass M_b is found to be strongly redshift
dependent, dropping from 10^6 solar masses at z=15 to 5000 solar masses at
z=100 as molecular cooling becomes effective. For z>>100, M_b rises again, as
CMB photons inhibit H_2-formation through the H^- channel. Finally, for z>>200,
the H_2^+ channel for H_2-formation becomes effective, driving M_b down towards
10^3 solar masses. With a standard CDM power spectrum with sigma_8=0.7, this
implies that a fraction 10^{-3} of all baryons may have formed luminous objects
by z=30, which could be sufficient to reheat the universe.Comment: Minor modifications to match published version. Molecular cooling
rates improved. 29 pages, with 6 figures included. Color figures and related
work at http://www.sns.ias.edu/~max/minmass.html (faster from the US), from
http://www.mpa-garching.mpg.de/~max/minmass.html (faster from Europe) or from
[email protected]
Gut Microbiota Induced by Pterostilbene and Resveratrol in High-Fat-High-Fructose Fed Rats: Putative Role in Steatohepatitis Onset
Resveratrol and its 2-methoxy derivative pterostilbene are two phenolic compounds that occur in foodstuffs and feature hepato-protective effects. This study is devoted to analysing and comparing the metabolic effects of pterostilbene and resveratrol on gut microbiota composition in rats displaying NAFLD induced by a diet rich in saturated fat and fructose. The associations among changes induced by both phenolic compounds in liver status and those induced in gut microbiota composition were also analysed. For this purpose, fifty Wistar rats were distributed in five experimental groups: a group of animals fed a standard diet (CC group) and four additional groups fed a high-fat high-fructose diet alone (HFHF group) or supplemented with 15 or 30 mg/kg bw/d of pterostilbene (PT15 and PT30 groups, respectively) or 30 mg/kg bw/d of resveratrol (RSV30 group). The dramatic changes induced by high-fat high-fructose feeding in the gut microbiota were poorly ameliorated by pterostilbene or resveratrol. These results suggest that the specific changes in microbiota composition induced by pterostilbene (increased abundances of Akkermansia and Erysipelatoclostridium, and lowered abundance of Clostridum sensu stricto 1) may not entirely explain the putative preventive effects on steatohepatitis.This research was funded by Ministerio de Economía y Competitividad-Fondo Europeo de Desarrollo Regional (grant number AGL-2015-65719-R MINECO/FEDER, UE), Instituto de Salud Carlos III CIBERobn (grant number CB12/03/30007); University of the Basque Country (grant number GIU 18/173)
Simulations of Hot Bubbles in the ICM
We review the general properties of the intracluster medium (ICM) in clusters
that host a cooling flow, and in particular the effects on the ICM of the
injection of hot plasma by a powerful active galactic nucleus (AGN). It is
observed that, in some cases, the hot plasma produces cavities in the ICM that
finally detach and rise, perhaps buoyantly. The gas dynamics induced by the
rising bubbles can help explain the absence of a cooled gas component in
clusters with a cooling flow. This scenario is explored using numerical
simulations.Comment: 13 pages, no figures. Accepted for publication in Modern Physics
Letters
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