Low degree hypersurfaces of projective toric varieties defined over a C1C_1 field have a rational point

Quasi algebraically closed fields, or $C_1$ fields, are defined in terms of a low degree condition. Namely, the field $K$ is $C_1$ if every degree $d$ hypersurface of the projective space $\mathbb{P}_K^n$ contains a $K$-point as soon as $d\leq n$. In this article we define a notion of low toric degree generalizing this condition for hypersurfaces of simplicial projective split toric varieties. This allows us to prove a particular case of the $C_1$ conjecture of Koll\'{a}r, Lang and Manin : any smooth separably rationally connected variety that can be embedded as such a hypersurface over a $C_1$ field has a rational point. Our results are based on the fact that the ambient toric varieties are Mori Dream Spaces : they are naturally endowed with homogeneous coordinates and their Minimal Model Program works in all cases.Comment: 46 pages. This is the long version of the article, with quite a lot of preliminaries aimed at non (toric) geometers. Changes from v1 : Statement and proof of the core theorem simplified, section about decomposition of toric rational contractions removed + minor correction

Essais d'estimation des débits de pointe de crue à partir des caractéristiques physiques et climatiques des bassins versants en région méditerranéenne

Dans une vallée, la définition des aménagements est étroitement liée aux risques d'inondation, c'est-à-dire à la probabilité de voir une caractéristique de crue, en général la cote maximale, atteindre ou dépasser une certaine valeur. Lorsqu'une station de mesure des hauteurs d'eau existe sur le site et a fonctionné suffisamment longtemps, l'analyse statistique des relevés historiques permet une évaluation correcte du degré de risque. Ces stations sont malheureusement en nombre insuffisant. Leur emplacement correspond rarement au site étudié, voire à la rivière concernée. Par ailleurs, les cotes sont très sensibles aux modifications topographiques (lits, ouvrages, obstacles...) et il vaut mieux travailler d'abord sur les débits, plus stables (régime hydrologique). Il apparaît donc la nécessité de disposer de méthodes d'évaluation des risques de débit en tout point d'une rivière et en absence de contrôle systématique. L'approche développée concerne la région Languedoc-Roussillon et consiste à estimer les débits de pointe de crues à partir de caractéristiques du bassin versant amont et de paramètres régionaux. (Résumé d'auteur

Quelques aspects combinatoires et arithmétiques des variétés toriques complètes

Dans cette thèse nous étudions deux aspects distincts des variétés toriques, l'un purement géométrique, sur C, et l'autre de nature arithmétique, sur des corps quasi algébriquement clos (corps C1). Les courbes extrémales qui engendrent le cône de Mori d'une variété torique projective sont des courbes primitives (V. Batyrev). En 2009, D. Cox et C. von Renesse ont conjecturé que les courbes primitives engendrent le cône de Mori de toute variété torique dont l'éventail est à support convexe, de dimension maximale. Nous présentons une famille de contre-exemples à cette conjecture et en proposons une nouvelle formulation basée sur la notion de contractibilité locale, généralisant la notion de contractibilité de C. Casagrande. Grâce aux couloirs, outils combinatoires que nous introduisons, nous montrons comment écrire une classe de 1-cycle donnée comme combinaison linéaire à coefficients entiers de classes de courbes toriques. Les couloirs nous permettent de donner une décomposition explicite de toute classe qui n'est pas contractible (couloirs droits) ainsi que de certaines classes contractibles (couloirs circulaires). Les corps C1 sont les corps sur lesquels l'existence de points rationnels dans une variété Y est assurée par le plongement en petit degré de Y dans un espace projectif (par définition) ou dans un espace projectif pondéré (d'après un théorème facile de Kollar). Pour un diviseur ample dans une variété torique dont l'éventail est simplicial et complet, nous montrons qu'il existe encore une notion de petit degré qui assure l'existence de points rationnels. Ceci nous permet notamment de montrer l'existence de points rationnels sur une large classe de variétés rationnellement connexes.In this thesis we study two distinct aspects of toric varieties, one purely geometric, over C, and the other of arithmetic nature, over quasi algebraically closed fields (C1 fields). Extremal curves, which generate the Mori cone of a projective toric variety, are primitive curves (V. Batyrev). In 2009, D. Cox and C. von Renesse conjectured that the classes of primitive curves generate the Mori cone of any toric variety whose fan has full dimensional convex support. We present a family of counterexamples to this conjecture and propose a new formulation based on the notion of local contractibility, generalizing the contractibility defined by C. Casagrande. Using the corridors, a combinatorial tool that we introduce, we show how to write any given 1-cycle class as a linear combination with integer coefficients of toric curve classes. Corridors enable us to give an explicit decomposition of any class that is not contractible (straights corridors) as well as contractible classes in some particular cases (circular corridors). C1 fields are those over which the existence of rational points on a variety Y is ensured by any small degree embedding of Y in a projective space (by definition) or in a weighted projective space (according to an easy theorem of Kollar). For an ample divisor in a toric variety whose fan is simplicial and complete, we show that there is also a notion of small degree which ensures the existence of rational points. This way, we show the existence of rational points on a large class of rationally connected varieties

Legal conditions for implementing EDRs in public fleets of vehicles

ITS 2016 - 11th ITS European Congress, Glasgow, ROYAUME-UNI, 06-/06/2016 - 09/06/2016This paper describes the needed legal conditions to implement Event Data Recorder in public fleets of vehicles. These conditions are specific because vehicles are owned by the government or local authorities and can be used by different kind of persons. The legal terms concern technical conditions and have to ensure the recommendations of the authority protecting privacy and personal data. Potential drivers have to be informed about the presence of an EDR in the vehicles and about the recorded data. Users are free to agree (or not) for recording data and their hierarchy can't access these data against their employees. The EDR has to not affect the vehicle safety and all vehicles have to be declared to the government. All these legal conditions have been applied for a French project but are valid for all European countries since they are based on the human right and the European laws.Cet article décrit la manière dont les conditions juridiques de la collecte et du traitement de données recueillies avec des enregistreurs embarqués dans des Îhicules (enregistreurs de données d'éÏnements de la route, EDR) doivent être prise en compte dans un contexte de recherche en sécurité routière à visée opérationnelle. En effet, ces données permettent généralement d'identifier les conducteurs des Îhicules, directement ou indirectement. Les conditions techniques et organisationnelles de la mise en oeuvre doivent donc respecter les législations européennes et françaises de protection des données à caractère personnel et de la vie priÎe ainsi que les recommandations des autorités de protection de ces données (la CNIL en France). Dans le contexte d'une expérimentation menée par des laboratoires de recherche français qui sert ici d'illustration, toutes les conditions juridiques relatives à la protection des droits des conducteurs ont été appliquées. Elles sont transposables dans les pays européens, car elles sont basées sur la réglementation communautaire et sur des principes issus de la convention européenne des droits de l'Homme

Fatores que influenciam a qualidade de serviços em academias de ginástica : consolidação e validação de modelos matemáticos aplicados

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia de Produção, 2018.O objetivo deste trabalho foi oferecer um modelo consolidado para manutenção da qualidade em serviços fitness contemplando a percepção do profissional de educação física, do cliente e do empresário deste segmento. Para alcançar este objetivo foi realizada uma pesquisa exploratória, com abordagem qualiquantitativa por meio de pesquisa sistemática da literatura e comparação com a opinião de clientes, empresários e profissionais através da análise textual de 27 discursos obtidos mediante aplicação de entrevistas semiestruturadas realizadas no Distrito Federal. Para as análises utilizou-se o software Iramuteq. Realizou-se análises de Classificação Hierárquica Descendente (CHD), Análise Fatorial Confirmatória (AFC), Análise de Similitude e Nuvem de Palavras. Foram encontradas seis classes: Fatores de Escolha, Manutenção do Negócio, Conveniência do Serviço, Diversidade de Horários e Programas, Resultado Pessoal e Atendimento e Confiabilidade do Serviço, sendo a Conveniência do Serviço e o foco em Resultado Pessoal comuns à todas as perspectivas. A partir destes resultados, foi proposto o Modelo de Manutenção do Serviço Fitness, composto por cinco etapas cíclicas de implementação.The objective of this work was to offer a consolidated model for maintaining quality in fitness services contemplating the perception of the physical education professional, the client and the entrepreneur of this segment. To achieve this objective an exploratory research was carried out, with a qualitative and quantitative approach through systematics research of the literature and comparison with the opinion of clients, entrepreneurs and professionals through the textual analysis of 27 speeches obtained through the application of semi-structured interviews conducted in the Federal District. The software Iramuteq was used for the analysis. Through the Analyzes of Descending Hierarchical Classification (CHD), Factorial Confirmatory Analysis (AFC), Similitude Analysis and Word Cloud, six classes were found: Choice Factors, Business Maintenance, Service Convenience, Schedule and Schedule Diversity, Personal Result, and Service Reliability and Service Convenience and focus on Personal Outcome common to all perspectives. From these results, the Fitness Service Maintenance Model was proposed, consisting of five cyclical stages of implementation

Estudio de ambientes interiores marinos

Programa Oficial de Doutoramento en Enerxía e Propulsión Mariña. 5014P01[Resumo] O informe da Axencia Europea de Seguridade Marítima realizado entre 2011-2014 para buques europeos, amosou que o 67% dos accidentes e incidentes producidos a bordo dos mesmos foron causados por erros humanos, dentro destes erros identificouse a fatiga como unha das posibles causas. Na resolución A.772 (18) "Factores que contribúen á fatiga" da Organización Marítima Internacional (OMI) defínese a fatiga como unha diminución no rendemento humano, polo que a OMI abordou a cuestión da fatiga mediante as horas de traballo e descanso a través de varios convenios e códigos, o Convenio sobre Normas de Formación, Titulación e Garda da Xente de Mar (STCW), o Código Internacional de Seguridade a Bordo (IGS) e mediante o Convenio sobre o Traballo Marítimo 2006 (CTM2006), este último desenvolvido pola Organización Internacional do Traballo (OIT). Ademais de facer fronte á fatiga a través das horas de traballo e descanso da xente de mar, o que serían as condicións de traballo a bordo, faise necesario tamén analizar as condicións ambientais nas que se desenvolve este traballo e que pode propiciar a aparición de fatiga ao tratarse de condicións extremas de temperatura, ruído, vibracións, etc. Por todo iso, na presente tese analizarase a aparición da fatiga desde dous aspectos diferenciados pero relacionados entre si. Por unha banda as condicións de traballo a bordo, entendendo estas condicións como a carga de traballo, é dicir, horas empregadas, persoal suficiente para realizar as tarefas, descanso, etc., e por outra banda, as condicións ambientais, entendendo estas condicións como a temperatura e o ruído que hai no lugar de traballo. Co fin de poder entender as condicións a bordo dun buque e a percepción que teñen os traballadores sobre a fatiga, buscouse coñecer a súa opinión mediante unha enquisa con preguntas encamiñadas a recoñecer as devanditas condicións. Por outra banda, para coñecer as condicións ambientais de ruído e temperatura empregáronse aparellos de medida en dous tipos de barcos nos que máis representación houbo de respostas á enquisa anteriormente citada.[Resumen] El informe de la Agencia Europea de Seguridad Marítima realizado entre el 2011-2014 a buques europeos, puso de manifiesto que el 67% de los accidentes e incidentes producidos a bordo de los mismos habían sido ocasionados por errores humanos, dentro de estos errores se identificó la fatiga como una de las posibles causas. En la resolución A.772 (18), “Factores que contribuyen a la fatiga” de la Organización Marítima Internacional (OMI) se define la fatiga como una disminución del rendimiento humano, es por esto que la OMI ha abordado la cuestión de la fatiga mediante las horas de trabajo y descanso a través de varios convenios y códigos, el Convenio sobre Normas de Formación, Titulación y Guardia de la Gente de Mar (STCW), el Código Internacional de Seguridad a Bordo (IGS) y mediante el Convenio sobre el Trabajo Marítimo 2006 (CTM2006), este último desarrollado por la Organización Internacional del Trabajo (OIT). Además de hacer frente a la fatiga a través de las horas de trabajo y descanso de la gente de mar, lo que serían las condiciones de trabajo a bordo, se hace necesario también analizar las condiciones ambientales en las que se desarrolla este trabajo y que puede propiciar la aparición de fatiga al tratarse de condiciones extremas de temperatura, ruido, vibraciones, etc. Por todo ello, en la presente tesis se analizará la aparición de la fatiga desde dos aspectos diferenciados pero relacionados entre sí. Por una parte las condiciones de trabajo a bordo, entendiendo estas condiciones como la carga de trabajo, es decir, horas empleadas, personal suficiente para realizar las tareas, descanso, etc., y por otra parte, las condiciones ambientales, entendiendo estas condiciones como la temperatura y el ruido que hay en el lugar de trabajo. Con el fin de poder entender las condiciones a bordo de un buque y la percepción que tienen los trabajadores sobre la fatiga, se ha buscado conocer su opinión mediante una encuesta con preguntas encaminadas a reconocer dichas condiciones. Por otra parte, para conocer las condiciones ambientales de ruido y temperatura se han empleado aparatos de medida en dos tipos de barcos en los que más representación hubo de respuestas a la encuesta anteriormente citada.[Abstract] The European Maritime Safety Agency report of the survey conducted on European vessels between 2011 and 2014 revealed that 67% of the accidents and incidents that occurred on-board were caused by human errors, of which fatigue was identified as a major cause. According to the A.772 (18) resolution ‘fatigue factors in manning and safety of the International Maritime Organization (IMO), fatigue is defined as a decrease in human performance. Thus, IMO has addressed the issue of fatigue through the Convention on Standards of Training, Certification and Guidance for Seafarers (STCW), the International Safety Management Code (ISM) and the Maritime Labour Convention 2006 (MLC2006); the latter was developed by the International Labour Organization (ILO). In addition to tackling fatigue through their working hours and rest periods, the seafarers faced uncomfortable working conditions on-board; it is therefore warranted that the environmental conditions of the work place be analysed to identify and eliminate the sources of conditions that induce fatigue, such as extreme temperatures, noise and vibrations. The present thesis analysed the appearance of fatigue in two different, but related context. On one hand, the work conditions on-board were considered, which included the workload (man-hours employed), ratio of numbers of personnel to the number of task, rest periods or breaks, etc. On the other hand, environmental conditions such as temperature and noise in the workplace were also considered. In order to comprehend the conditions on-board a ship as well as the perception of fatigue by workers, we sought the opinions of the seafarers through a questionnaire survey aimed at recognizing the factors contributing to fatigue. The environmental conditions of noise and temperature were assessed using measuring devices across two types of ships. More number of samples needs to be studied in the future for better representation of the results obtained

Transformations urbaines et diversités locales au Pirée: famille, emploi et chomage

[Δε διατίθεται περίληψη / no abstract available

Increasing Internodal Distance in Myelinated Nerves Accelerates Nerve Conduction to a Flat Maximum

SummaryPredictions that conduction velocities are sensitive to the distance between nodes of Ranvier in myelinated axons have implications for nervous system function during growth and repair [1–3]. Internodal lengths defined by Schwann cells in hindlimb nerves, for example, can undergo a 4-fold increase during mouse development, and regenerated nerves have internodes that are uniformly short [4, 5]. Nevertheless, the influence of internodal length on conduction speed has limited experimental support. Here, we examined this problem in mice expressing a mutant version of periaxin, a protein required for Schwann cell elongation [4]. Importantly, elongation of mutant Schwann cells was retarded without significant derangements to myelination or axon caliber. In young mice with short mutant Schwann cells, nerve conduction velocity was reduced and motor function was impaired. This demonstrates a functional relationship between internodal distance and conduction speed. Moreover, as internodes lengthened during postnatal growth, conduction velocities recovered to normal values and mutant mice exhibited normal motor and sensory behavior. This restoration of function confirms a further prediction by Huxley and Stämpfli that conduction speeds should increase as internodal distances lengthen until a “flat maximum” is reached, beyond which no further gains in conduction velocity accrue [6]