398 research outputs found
Séries hypergéométriques basiques, q-analogues des valeurs de la fonction zêta et séries d’Eisenstein
No full textWe study the arithmetic properties of q-analogues of values ζ(s) of the Riemann zeta function, in particular of the values of the functions ζq(s)=Σ∞ k=₁ qkΣ dk d s⁻¹, s= 1,2,..., where q is a complex number with |q|<1 (these functions are also connected with the automorphic world). The main theorem of this article is that, if 1/q is an integer different from ±1, and if M is a sufficiently large odd integer, then the dimension of the vector space over ℚ which is spanned by 1,ζq(3),ζq(5),...,ζq(M) is at least c₁√M}, where c₁=0.3358. This result can be regarded as a q-analogue of the result of Rivoal and of Ball and Rivoal that the dimension of the vector space over ℚ which is spanned by 1,ζ(3),ζ(5),...,ζ(M) is at least c₂log M, with c₂=0.5906. For the same values of q, a similar lower bound for the values ζq(s) at even integers s provides a new proof of a special case of a result of Bertrand saying that one of the two Eisenstein series E₄(q) and E₆(q) is transcendental over ℚ for any complex number q such that 0<|q|<1
Handicap, jeunesse et vie sociale, Actes du colloque de Nouméa de juillet 2022, F. Faberon et M. Rivoal (dir.)
No full textInternational audienc
Current challenges in poultry meat safety
No full textCurrent challenges for poultry and poultry meat include traditional (Salmonella and Campylobacter) and emerging (Arcobacter and Helicobacter) biological hazards, as well as the spread of antimicrobial resistance leading to treatment failure against bacterial infections. In recent years, different control strategies have been studied and implemented both on live poultry and on poultry meat. Strategies at farm level, such as biosecurity, vaccination, feed additives, as well as at the slaughterhouse, such as poultry carcass decontamination, are reviewed along with new genomics approaches focused on improving the gut health and the disease resistance of animals. Moreover, new risk-based metrics such as the Appropriate Level of Protection, Food Safety Objective, and Performance Objective, are described as new concepts to increase the food safety for consumers. A holistic approach is envisaged involving all actors of human and veterinary medicine, animal husbandry, agriculture, environment, and legislation to face these risks
Etude des temps de reconnaissance en mémoire à court terme
No full textSummary
In a continuous recognition task, the subject was asked to say whether the stimuli were « new » or « old » ; response latencies were recorded. The nature and structure of stimuli involved 3 experimental conditions : M 1 : meaningful words presented in blocks — 5 blocks of 16 stimuli each ; M 2 : one list of 80 meaningful words ; C : one list of 3-digit numbers — 160 stimuli.
In any given list, 45 % of the stimuli appeared twice. The number (Δ) of items intervening between two presentations of a single stimulus item was 0, 1, 2, 3, 5, 7 and 11 in the 3 conditions. The following results were obtained :
1) more interference occurred with material C than wiih material M 1 and M2;
2) forgetting was higher and recognition times longer with M 1 than with M 2, rehearsal having possibly interfered with the processing of the following block ;
3) forgetting increased as a function of Δ, until Δ = 3, this being followed by a plateau.
Within the framework of Wickelgren and Norman model, Receiver Operating Characteristic curves were plotted, the hypothesis being that the response latencies were an index of certainty. The results supported the hypothesis. Two mnemonic levels were then distinguished : short-term memory where forgetting increases as a function of Δ, when Δ varies between 0 and 3, and long-term memory, when Δ > 3, where performance is approaching a steady state.Résumé
Dans une tâche de reconnaissance continue, le sujet doit indiquer si des stimulus sont « nouveaux » ou « déjà vus » ; les temps de réponse sont enregistrés. Trois conditions expérimentales sont déterminées d'après la nature et la structure des stimulus : M 1 : mots significatifs présentés par blocs de 16 stimulus ; M 2 : mots significatifs présentés en une liste ininterrompue ; C : nombres de 3 chiffres présentés en une liste ininterrompue.
Le nombre de stimulus intercalés entre deux présentations d'un même stimulus (Δ) est de 0, 1, 2, 3, 5, 7 et 11 dans les trois expériences. Les résultats sont les suivants :
1) le matériel C entraîne plus d'interférence que M 1 et M 2 ;
2) M 1 suscite plus d'oubli et des temps de reconnaissance plus longs que M 2 car les sujets ont la possibilité de faire des autorépétitions qui interfèrent avec l'appréhension du bloc suivant;
3) l'oubli croît en fonction de Δ jusqu'à Δ = 3, puis atteint un plateau.
Dans le cadre du modèle de Wickelgren et Norman (1966), des CCO sont construites en faisant l'hypothèse que le temps de réponse peut être pris comme indice de certitude; nos résultats confirment cette hypothèse. On distingue alors deux niveaux mnémoniques, la mémoire à court terme qui intervient pour 0 3) qui se manifeste comme un état stable des performances.Gérard-Rivoal Claire. Etude des temps de reconnaissance en mémoire à court terme. In: L'année psychologique. 1972 vol. 72, n°1. pp. 81-99
Les bains de Rasm el-Hajal (رسم الحجل)
No full textDate : juin 2008 Responsables : T. FOURNET (Ifpo) ; M. RIVOAL (Ifpo/MOM, Doctorante) Le site de Rasm el-Hajal (Syrie, région de Khanaser) était jusqu'à ces dernières années principalement connu par les missions épigraphiques et les prospections aériennes réalisées dans la première moitié du xxe siècle. Les prospections menées par Marion Rivoal en 2006 puis 2007 avaient permis d'en préciser la lecture et d'en dresser un plan d'ensemble. Elles avaient également été l'occasion de constater l'imp..
The shadows of Beiteddin Palace: politics of hospitality and struggles for sovereignty between presidential and regional powers in Lebanon
No full textInternational audienceThis article interrogates the notion that the state in Lebanon is a constantly weakened super structure whose political actions are hampered by a generalised sectarian system. Building on the recent literature that challenges the rhetoric of ‘the failed state’ in Lebanon, this article focuses on the notion of sovereignty and its symbolic expressions. Moving away from discussions of violence to analyze the relationship between the state and Lebanese regional powers, the article considers how hospitality plays a significant part in acting out different expressions of sovereignty. The author observes the competition between the Lebanese Head of State (President Emile Lahoud) and a regional Lord (Walid Jumblat) in their attempt to perform ‘being at home’ in the Lebanese Mountain. In this regard, the region of the Shuf becomes emblematic as a space that links sovereignty to hosting in a particular symbolic place: the Emirs’ Palace of Beiteddin. The author argues that by accepting multiple and sometimes conflicting sources of power, the Lebanese political system follows a model of ‘piling-up’ layers of sovereignty
Selberg's integral and linear forms in zeta values
No full textAbstractUsing Selberg's integral, we present some new Euler-type integral representations of certain nearly poised hypergeometric series. These integrals are also shown to produce linear forms in odd and/or even zeta values that generalize previous work of the author
Is Euler's constant a value of an arithmetic special function?
No full textEuler's constant γ is one of the mathematical constants with the most different analytic representations, probably on par with π. Yet, none of these representations proves that γ is a value of an E-function, a G-function or an M-function at an algebraic point. In fact, it is plausible that no such representation of γ exists with these three arithmetic special functions, and thus the arithmetic nature of γ might not be determined by the powerful Diophantine theorems of Siegel-Shidlovsky, Chudnovsky and Nishioka. Nonetheless, we explain here why certain of these representations show that γ is not far from being a special value of both E-functions and M-functions, while a similar connection to G-functions is still elusive. We also present a new family of series summing to γ, which generalize an identity of Vacca
Ecritures suspendues, vies engagées. Traverser la guerre civile libanaise
No full textInternational audienceIn this article the author explores the impossible narration of the civil war in Lebanon through the trajectories of social anthropologists who studied prewar Lebanon but postponed the writing of their ethnographies for twenty years. Then, she explores the atypical form of the memories of Lebanese who went through the war experience using her own ethnography of postwar Lebanon. Despite being a major social transformation, the war is presented by the Lebanese as something they « went through » rather than « lived », as if they were the observers of a play - a mix of nostalgia and taste for drama - much as the anthropologists whose writing was postponed by the events. The author uses biographical approaches and Johannes Fabian’s notion of coevaleness as methodological ressources which needs to be discussed in an attempt to describe contemporary Lebanese society.À partir du croisement entre son expérience de la société libanaise de l’après-guerre civile, des trajectoires d’anthropologues ayant réalisé des ethnographies du Liban avant-guerre qu’ils n’ont publiées que 20 ans plus tard et des formes mémorielles sécrétées par les Libanais qui ont vécu la guerre, l’auteur explore dans cet article l’impossible narration d’un événement s’apparentant pourtant à une transformation sociale radicale. Entre nostalgie et expression théâtralisée du conflit qui en autorise le déni de réalité, l’article montre que la guerre a été plus traversée que vécue par les Libanais, comme par les observateurs dont elle a perturbé la pratique. Ceci l’amène à mettre en perspective l’approche biographique et la co-temporalité de Johannes Fabian comme ressources méthodologiques pertinentes pour saisir la société libanaise contemporaine
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