Supersymmetric quantum theory and (non-commutative) differential geometry

We reconsider differential geometry from the point of view of the quantum theory of non-relativistic spinning particles, which provides examples of supersymmetric quantum mechanics. This enables us to encode geometrical structure in algebraic data consisting of an algebra of functions on a manifold and a family of supersymmetry generators represented on a Hilbert space. We show that known types of differential geometry can be classified in terms of the supersymmetries they exhibit. Replacing commutative algebras of functions by non-commutative *-algebras of operators, while retaining supersymmetry, we arrive at a formulation of non-commutative geometry encompassing and extending Connes' original approach. We explore different types of non-commutative geometry and introduce notions of non-commutative manifolds and non-commutative phase spaces. One of the main motivations underlying our work is to construct mathematical tools for novel formulations of quantum gravity, in particular for the investigation of superstring vacua.Comment: 125 pages, Plain TeX fil

The Gravitational Sector in the Connes-Lott Formulation of the Standard Model

We study the Riemannian aspect and the Hilbert-Einstein gravitational action of the non-commutative geometry underlying the Connes-Lott construction of the action functional of the standard model. This geometry involves a two-sheeted, Euclidian space-time. We show that if we require the space of forms to be locally isotropic and the Higgs scalar to be dynamical, then the Riemannian metrics on the two sheets of Euclidian space-time must be identical. We also show that the distance function between the two sheets is determined by a single, real scalar field whose VEV sets the weak scale.Comment: Latex file, 29 page

Approche hybride chirurgicale et endovasculaire lors d'artériopathie périphérique oblitérante multiétagée des membres inférieurs

Contexte : La prise en charge de l'artériopathie périphérique et de l'ischémie critique a fortement évolué depuis plusieurs années en faveur des traitements endovasculaires. En effet, la revascularisation chirurgicale a prouvé son efficacité à moyen et long terme mais reste invasif avec un temps de séjour hospitalier prolongé. Plusieurs études ont démontré l'intérêt de la prise en charge endovasculaire afin de réduire la morbidité et diminuer la durée de séjour. Néanmoins, elle n'offre pas des taux de succès à moyen et long terme équivalent à la chirurgie. Une approche hybride chirurgicale et endovasculaire cherchant à utiliser les avantages des 2 techniques pourrait permettre d'obtenir des taux de succès élevé avec un taux de complication plus faible. Objectifs : Nos objectifs sont d'analyser rétrospectivement la population de patients ayant bénéficié d'une approche hybride pour la revascularisation des membres inférieurs pour une claudication intermittente ou une ischémie critique. Le taux de mortalité à 30 jours ainsi que les complications locales et systémiques seront relevés. Les taux de perméabilité à 12 mois seront également analysés. Finalement, le taux de sauvetage de membre ainsi que le pourcentage de déambulation seront reportés. Méthodes : La cohorte de patients ayant bénéficié d'une approche hybride dans le service de chirurgie thoracique et vasculaire du CHUV de janvier 2008 à janvier 2011 seront systématiquement inclus dans l'analyse. L'ensemble des données démographiques et angiologiques seront reportés dans un cahier d'observation. De plus, tous les événements liés à des complications locales ou systémiques seront également analysés. Les décès seront reportés. Un appel téléphonique au patient et à son médecin traitant permettra de connaître l'état de santé actuel du patient ainsi que sa capacité à la marche. Une analyse statistique comportant une courbe de survivre selon Kaplan Meier permettra d'analyser le taux de perméabilité ainsi que la survie à moyen terme. Résultats escomptés : Les résultats devraient nous démontrés un taux de perméabilité supérieur ou équivalent à la prise en charge séparée chirurgicale ou endovasculaire. De plus les complications locales devraient être inférieures au taux obtenus dans la prise en charge chirurgicale. Le taux de sauvetage de membre et de déambulation pourrait être identique à la prise en charge chirurgicale. Plus value escomptés : L'approche hybride pour la revascularisation des membres inférieurs reste peu décrite dans la littérature. Cette étude permettra de décrire de manière globale une grande cohorte de patients homogène ayant bénéficié de cette approche dans un seul centre. Elle démontrera aussi l'éventuel intérêt de ce type de prise en charge pour les patients souffrant d'une artériopathie périphérique multiétagée

Experimental investigation into localized instabilities of mixed Rayleigh-Bénard-Poiseuille convection

The stability of the Rayleigh-Bénard-Poiseuille flow in a channel with large transverse aspect ratio (ratio of width to vertical channel height) is studied experimentally. The onset of thermal convection in the form of ‘transverse rolls' (rolls with axes perpendicular to the Poiseuille flow direction) is determined in the Reynolds-Rayleigh number plane for two different working fluids: water and mineral oil with Prandtl numbers of approximately 6.5 and 450, respectively. By analysing experimental realizations of the system impulse response it is demonstrated that the observed onset of transverse rolls corresponds to their transition from convective to absolute instability. Finally, the system response to localized patches of supercriticality (in practice local ‘hot spots') is observed and compared with analytical and numerical results of Martinand, Carrière & Monkewitz (J. Fluid Mech., vol. 502, 2004, p. 175 and vol. 551, 2006, p. 275). The experimentally observed two-dimensional saturated global modes associated with these patches appear to be of the ‘steep' variety, analogous to the one-dimensional steep nonlinear modes of Pier, Huerre & Chomaz (Physica D, vol. 148, 2001, p. 49

Valuing Access to our Public Lands: A Unique Public Good Pricing Experiment

We report the findings of a unique nation-wide experiment to price access to our public lands. In 2004, the U.S. Federal Lands Recreation Enhancement Act mandated the creation of a new annual pass to cover all federal recreation sites that charge an entrance or access fee. Our task was to assist federal policymakers in determining an appropriate price for this new pass. Toward that end, we administered a contingent valuation phone survey to over 3700 households to estimate households willingness to pay (WTP) for the new pass at a variety of different prices. Our innovative experimental design allows us to estimate the degree of hypothetical bias in the sample and calibrate our WTP estimates to reflect actual purchasing decisions. In a sample of the general U.S. population most of whom have little experience with similar federal passes respondents tend to greatly exaggerate their WTP for the pass when contrasted with previous pass sales. A sample of recent pass purchasers, however, exhibits little bias. This confirms recent research showing that market experience can be an effective means to mitigate hypothetical bias.Land Economics/Use,

A systematic review of tuberculosis detection and prevention studies in prisons

Many studies have demonstrated that prisons are hotspots of tuberculosis disease and transmission. Despite this, it remains unclear which interventions are most effective at controlling tuberculosis in prisons. The objective was to determine the study designs used to investigate tuberculosis control in prisons, and the efficacy of interventions undertaken. This systematic review included published studies which had the aim of reducing TB incidence or prevalence, or increasing the number of people screened for active pulmonary tuberculosis in incarcerated populations. 2,429 records were identified, 178 full-text articles were screened, and 17 studies included. The majority of reports were before/after or prospective non-comparative studies. The median study duration was 23 months (range 5-144). The most common intervention was the introduction of active case finding (10/17 studies) but the timing and methods varied. Comparable pre- and post intervention outcome values were infrequently reported; therefore, it was not possible to quantify the efficacy of interventions. Data from studies of tuberculosis control in prisons is limited by a lack of: controlled interventions, reporting of pre-intervention methods, and comparable pre- and post-intervention outcomes. Prospective comparative trials of adequate duration to determine trends in incidence are necessary to understand which interventions are effective in prisons