A nonlinear Bloch model for Coulomb interaction in quantum dots

In this paper we first derive a Coulomb Hamiltonian for electron--electron interaction in quantum dots in the Heisenberg picture. Then we use this Hamiltonian to enhance a Bloch model, which happens to be nonlinear in the density matrix. The coupling with Maxwell equations when interaction with an electromagnetic field is also considered from the Cauchy problem point of view. The study is completed by numerical results and a discussion about the advisability of neglecting intra-band coherences, as is done in part of the literature.Comment: 17 pages. Journal of Mathematical Physics (2014) \`a para\^itr

Cooperative domain type interlayer sp3sp^3-bond formation in graphite

Using the classical molecular dynamics and the semiempirical Brenner's potential, we theoretically study the interlayer sigma bond formation, as cooperative and nonlinear phenomena induced by visible light excitations of a graphite crystal. We have found several cases, wherein the excitations of certain lattice sites result in new interlayer bonds even at non-excited sites. We have also found that, a new interlayer bond is easier to be formed around a bond, if it is already existing. As many more sites are going to be excited, the number of interlayer bonds increases nonlinearly with the number of excited sites. This nonlinearity shows 1.7 power of the total number of excited sites, corresponding to about three- or four-photon process.Comment: 7 pages, 8 figure

Revealed Preference Theory, Rationality, and Neoclassical Economics: Science or Ideology

Revealed Preference Theory (Samuelson 1938) is an attempt to establisheconomic theory as a genuine empirical science by ridding it of nonempiricalpsychological concepts. Samuelson’s goal was to rid economictheory of the last vestiges of utility analysis. Samuelson structured histheory on a set of preference axioms that would explain the choices ofeconomic agents. But revealed preference theory is rendered problematicbecause decision making is structured therein on preferences thatconform to an implicit postulate of rationality. Matters are furthercompounded by the fact that despite theoretical support offered bytheorists such as Varian, the empirical results demonstrate that agentdecision making is often at variance with the formal axioms of revealedpreference. The issue is not solved even when decision making isconstrued within the context of imperfect, that is, ‘bounded rationality’.I argue that neoclassical economic theory is best understood as a formof rule utilitarianism. In this regard, neoclassical economics isunavoidably value-laden and should be construed as an aspect ofnormative welfare economics. Thus efforts by theorists such as Vanbergto salvage the assumed scientific credentials of neoclassical economicsby construing the postulate of rationality in evolutionary terms areseen as problematic. Neoclassical economic theory is to be viewedessentially then as an ideology that presents a particular theory ofhuman behaviour. It is this theory that serves as the foundations ofmodern capitalism and its practise as neoliberal economics. This is theanthropological question then: is such an ideology socially optimal forhumans as social animals in terms of efficiency and equity

A theoretical approach to thermal noise caused by an inhomogeneously distributed loss -- Physical insight by the advanced modal expansion

We modified the modal expansion, which is the traditional method used to calculate thermal noise. This advanced modal expansion provides physical insight about the discrepancy between the actual thermal noise caused by inhomogeneously distributed loss and the traditional modal expansion. This discrepancy comes from correlations between the thermal fluctuations of the resonant modes. The thermal noise spectra estimated by the advanced modal expansion are consistent with the results of measurements of thermal fluctuations caused by inhomogeneous losses.Comment: 10 pages, 4 figure

Examining the Youth Multi-Sport Event Environment: Implications towards athlete development and transitioning.

Many factors are associated with a person’s attitude formation and intention towards a behavior. In this study, we examined organizational factors that helped form young athletes attitudes regarding their future plans in high performance sport. Through a mixed method survey design, data was collected from 207 young pre-elite athletes who competed during the 2017 Commonwealth Youth Games in Bahamas. Several organizationally controlled aspects of the games environment were found to contribute to young athlete’s satisfaction with the event including their accommodations, available information regarding their sport and finally, the social and cultural activities during games-time. However, satisfaction with the games environment was not predictive of young athletes future intentions to remain in sport. Qualitative thematic coding denoted two key themes related to athlete plans to continue in high performance sport: level of satisfaction and learning. Further, qualitative results revealed five main impediments to continuing in high performance sport specifically, physiological, psychological, performance, environment and life concerns. The paper contributes to our understanding of the controllable and uncontrollable social and environmental factors in a multi-sport international event. Nationally controlled factors that influence young athletes attitude formation, specifically their satisfaction and intentions to remain in sport

Mieux gérer l'information sur les périmètres irrigués collectifs : un outil au service de leur efficacité

International audienceAu Mali, l'Office du Niger gère un périmètre d'irrigation entièrement gravitaire de 70 000 ha. La programmation et le suivi de la maintenance de ce réseau sont assurés paritairement par l'Office du Niger et des représentants des usagers. Ces activités rencontrent de grandes difficultés pour mobiliser l'information nécessaire. En partant des pratiques actuelles des différents acteurs et en explicitant, avec eux, les procédures de gestion employées, une application informatique a été mise au point (le système d'information pour la maintenance à l'Office du Niger) afin de gérer les données de manière uniformisée, d'en assurer le traitement informatique et de les stocker. Son implantation dans les divers services de l'Office du Niger (service de gestion de l'eau, service des aménagements hydrauliques, bureau des procédures de marchés) a fait l'objet de formations et d'actions d'accompagnement. Ce système assure les fonctionnalités de programmation et de suivi des interventions de maintenance ainsi que la gestion de l'ensemble des données de références que sont les composants du réseau d'irrigation - canaux, cavaliers et pistes, ouvrages - et les nomenclatures. La lenteur du processus d'intégration de ce nouveau système est due d'une part à la charge de travail importante pour mettre en place les données de référence, et d'autre part à la volonté de laisser les agents des services de l'Office s'approprier cet outil à leur rythme. Cependant, le manque de supports et d'assistance informatique fonctionnelle, rapprochée et permanente a pénalisé ce processus, de même l'engagement de la hiérarchie est indispensable pour intégrer pleinement ce logiciel dans la gestion. Si, aujourd'hui, l'emploi du logiciel n'est pas encore systématisé pour la gestion de la maintenance, les réflexions collectives qui ont généré son élaboration ont permis de confronter et d'uniformiser le vocabulaire et les pratiques de gestion de la maintenance des différents services de l'Office du Niger. Des supports d'information, principalement cartographiques, destinés aux paysans et à leurs représentants au sein des comités paritaires, seront prochainement soumis à la critique de ces usagers. Ce type de démarche et de concepts devrait trouver des applications sur d'autres périmètres du même type

Incidence and Risk Factors of First-Line HAART Discontinuation: Is it Worth Choosing Competing Risk or Standard Survival Approaches?

International audienceObjectives: To estimate the incidences of first-line HAART discontinuation (for intolerance, treatment failure or treatment simplification) and their risk factors by standard survival (1-KM, Cox model) or competing risk approach (CIF, Fine-Gray model) in HIV infected patients. Methods: We studied 1136 patients receiving first-line Highly Active Antiretroviral Therapies (HAART), aged over 18 years, from the Dat'AIDS cohort, Toulouse, France, between January 2000 and June 2008. Cumulative incidence was estimated with 1-KM and CIF estimators and risk factors with Cox and Fine-Gray models. Results: There were 265 discontinuations for intolerance, 136 simplifications, 101 treatment failure and 274 other reasons. One year incidences were 19.0% versus 16.8%, 8.0% versus 6.0%, 6.3% versus 4.8% and 20.0% versus 17.3%, with the estimators 1-KM and CIF, respectively. For intolerance, both models identified similar risk factors. For risk factors of simplification or treatment failure, results differed by the model. Conclusions: As expected, the 1-KM overestimates the incidence of treatment discontinuation. For early and frequent events such as intolerance, the Cox and the Fine-Gray models appear to give similar results. For late and rare events, potentially exposed to competing risk, results differed. The common or specific nature of a factor may also play a role

Prevalence and Factors Related to Anaemia in Children Aged 6–59 Months Attending a Quaternary Health Facility in Maputo, Mozambique

Globally, anaemia prevails as a public health issue, being also a concern in Mozambique, where about two-thirds of children 6-59 months of age are affected by this condition. We carried out this study to estimate anaemia prevalence and evaluate structural determinants and haematological parameters association among children aged 6-59 months attending pediatric inpatient and outpatient services in a Quaternary Health Facility in Maputo City Province, Mozambique. We collected data from 637 inpatients or outpatients who attended pediatric consultations at the Maputo Central Hospital. The overall rate of anaemia in children aged 6-59 months was 62.2% (396/637), with 30.9% moderate anaemia (197/637), 23.9% mild anaemia (152/637), and 7.4% severe anaemia (47/637). Among our study participants, critical factors for anaemia were those concerning the age group, child´s caregiver schooling, malaria and size of the liver.info:eu-repo/semantics/publishedVersio