169 research outputs found
Spectral instability of some non-selfadjoint anharmonic oscillators
The purpose of this Note is to highlight the spectral instability of some
non-selfadjoint differential operators, by studying the growth rate of the
norms of the spectral projections associated with their eigenvalues.
More precisely, we are concerned with the complex Airy operator and even
anharmonic oscillator. We get asymptotic expansions for the norm of the
spectral projections associated with the large eigenvalues, extending the
results of Davies and Davies-Kuijlaars
ThĂ©orie dâaction de la stratĂ©gie nationale de prĂ©vention de la grippe saisonniĂšre (GRIPS)
La stratĂ©gie nationale de prĂ©vention de la grippe saisonniĂšre (GRIPS) 2015-20181 vise Ă rĂ©duire « le nombre de cas maladie sĂ©vĂšre due Ă la grippe saisonniĂšre, particuliĂšrement chez les personnes Ă risque accru de complications ». La stratĂ©gie GRIPS se compose de trois domaines dâactions : 1) la recherche en santĂ© publique ; 2) la protection des patients ; 3) la promotion de la vaccination. Pour ces trois domaines dâaction, des objectifs, des mesures-clĂ©s et des rĂ©sultats attendus sont dĂ©crits dans la stratĂ©gie GRIPS.
LâOffice fĂ©dĂ©ral de la santĂ© publique (OFSP) a confiĂ© au Centre dâĂ©valuation et dâexpertise en santĂ© publique (CEESAN) de lâInstitut universitaire de mĂ©decine sociale et prĂ©ventive (IUMSP) le mandat de construire une thĂ©orie dâaction (TA) de sa stratĂ©gie GRIPS, et dâĂ©laborer des indicateurs permettant de mesurer les rĂ©sultats et lâimpact de celle-ci. Cette thĂ©orie dâaction et les indicateurs qui sây rattachent pourront Ă©galement ĂȘtre utiles Ă la construction et la programmation de stratĂ©gies futures de prĂ©vention de la grippe saisonniĂšre par lâOFSP
Etat des lieux sur la prescription de PrEP auprĂšs dâun Ă©chantillon de mĂ©decins en Suisse
Le mandat
LâOffice fĂ©dĂ©ral de la santĂ© publique (OFSP) a chargĂ© le Centre dâĂ©valuation et dâexpertise en santĂ© publique (CEESAN, IUMSP) de rĂ©aliser une Ă©tude permettant de disposer rapidement dâun premier Ă©tat des lieux concernant la prescription de prophylaxie prĂ©-exposition contre le VIH (PrEP) en Suisse.
LâĂ©tude : population cible et mĂ©thode
Lâobjectif de cette Ă©tude est dâestimer le nombre dâusagers auxquels les mĂ©decins rĂ©pondants ont remis soit de lâinformation au sujet de la PrEP, soit une ordonnance pour une premiĂšre prescription de PrEP, ou encore une ordonnance pour un renouvellement de PrEP.
Nous avons dĂ©fini comme population cible les mĂ©decins responsables des services de conseil et de dĂ©pistage volontaire du VIH (VCT), tels quâils sont recensĂ©s en Suisse par lâOFSP, ainsi quâune sĂ©lection de mĂ©decins qui ont une pratique dans la prescription de traitements antirĂ©troviraux (mĂ©decins collaborant avec la Swiss HIV Cohort Study, SHCS).
Il sâagit dâune Ă©tude transversale Ă vocation descriptive, avec une collecte de donnĂ©es rĂ©alisĂ©e du 14 mars au 24 avril 2017 au moyen dâun questionnaire en ligne adressĂ© Ă 138 mĂ©decins
Intermittent Attractive Interactions Lead to Microphase Separation in Non-motile Active Matter
Non-motile active matter exhibits a wide range of non-equilibrium collective
phenomena yet examples are crucially lacking in the literature. We present a
microscopic model inspired by the bacteria {\it Neisseria Meningitidis} in
which diffusive agents feel intermittent attractive forces. Through a formal
coarse-graining procedure, we show that this truly scalar model of active
matter exhibits the time-reversal-symmetry breaking terms defining the {\it
Active Model B+} class. In particular, we confirm the presence of microphase
separation by solving the kinetic equations numerically. We show that the
switching rate controlling the interactions provides a regulation mechanism
tuning the typical cluster size, e.g. in populations of bacteria interacting
via type IV pili.Comment: 7 pages (4 figures) of main text plus 12 pages (2 figures) of
supplementary informatio
Ăvaluation du stock de carbone et de la productivitĂ© en bois d'un parc Ă karitĂ©s du Nord-Cameroun
In the sudanian zones of northern Cameroon, the steady influx of migrants is causing much land clearance in large swathes of savannah lands. Creating denser stands of relict tree populations would be of value at once for agronomic, economic and environmental reasons. A method for evaluating the carbon stored in aerial biomass is proposed here for a village area of shea trees (Vitellaria paradoxa). The aim is to introduce agroforestry projects that will be eligible for the Clean Development Mechanism (CDM) as from 2012. In addition, an evaluation of fuelwood productivity in the area, using pollarding methods, was conducted for about thirty trees over a three-year period. A series of allometric equations was developed (for six shea specimens and one specimen each of Anogeissus leiocarpus and Combretum nigricans), establishing a ratio between aerial biomass and the diameter of the trunk (at chest height or at the branch base) or the surface area of the crown. This provided an estimation of carbon stocks per tree, and then per plot. Given the human pressure exerted on the tree zone, it was established that an 8-year rotation between pollarding operations would offer a healthy trade-off between the various interests involved. These studies offer a preliminary approach that will need to be consolidated with hindsight. Keywords: Vitellaria paradoxa, Clean Development Mechanism (CDM), pollarding, fuelwood productivity, carbon, agroforestry, sudanian zone, Cameroon
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