Switched Spatial Impulse Response Convolution as an Ambisonic Distance-Panning Function

Ambisonics offers a robust and effective approach to the recording, processing and delivery of Spatial Audio. The Ambisonic system is often considered to provide a perceptually and computationally advantageous Spatial Audio experience in comparison to typical Binaural systems. This is true even when an end-step Binaural render is required, as is typical in Virtual or Augmented Reality systems which naturally imply audio delivery via headphones. Standard Ambisonic processing allows for the rotation of a sound field around an origin position. There is not, however, a strongly established means of modulating the radial distance of a virtual sound source from the origin. This paper presents a potential solution to an Ambisonic distance-panning function for both static and dynamic virtual sources in the form of a FOA (First Order Ambisonics) Switched-SIR (Spatial Impulse Response) Convolution Reverberator. This includes a presentation of the framework for such a function, and an analysis of audio rendered using prototype scripts

Deficits of psychomotor and mnesic functions across aging in mouse lemur primates.

Owing to a similar cerebral neuro-anatomy, non-human primates are viewed as the most valid models for understanding cognitive deficits. This study evaluated psychomotor and mnesic functions of 41 young to old mouse lemurs (Microcebus murinus). Psychomotor capacities and anxiety-related behaviors decreased abruptly from middle to late adulthood. However, mnesic functions were not affected in the same way with increasing age. While results of the spontaneous alternation task point to a progressive and widespread age-related decline of spatial working memory, both spatial reference and novel object recognition (NOR) memory tasks did not reveal any tendency due to large inter-individual variability in the middle-aged and old animals. Indeed, some of the aged animals performed as well as younger ones, whereas some others had bad performances in the Barnes maze and in the object recognition test. Hierarchical cluster analysis revealed that declarative-like memory was strongly impaired only in 7 out of 25 middle-aged/old animals. These results suggest that this analysis allows to distinguish elder populations of good and bad performers in this non-human primate model and to closely compare this to human aging.journal article20142015 01 09importe

Effects of Chronic Calorie Restriction or Dietary Resveratrol Supplementation on Insulin Sensitivity Markers in a Primate, Microcebus murinus

The prevalence of diabetes and hyperinsulinemia increases with age, inducing metabolic failure and limiting lifespan. Calorie restriction (CR) without malnutrition delays the aging process, but its long-term application to humans seems difficult. Resveratrol (RSV), a dietary polyphenol, appears to be a promising CR mimetic that can be easily administered in humans. In this work, we hypothesized that both CR and RSV impact insulin sensitivity in a non-human primate compared to standard-fed control (CTL) animals. Four- to five-year-old male grey mouse lemurs (Microcebus murinus) were assigned to three dietary groups: a CTL group, a CR group receiving 30% fewer calories than the CTL and a RSV group receiving the CTL diet supplemented with RSV (200 mg·day−1·kg−1). Insulin sensitivity and glycemia were assessed using an oral glucose tolerance test (OGTT) and the homeostasis model assessment of insulin resistance (HOMA-IR index) evaluation after 21 or 33 months of chronic treatment. Resting metabolic rate was also measured to assess the potential relationships between this energy expenditure parameter and insulin sensitivity markers. No differences were found after a 21-month period of treatment, except for lower glucose levels 30 min after glucose loading in CR animals. After 33 months, CR and RSV decreased glycemia after the oral glucose loading without decreasing fasting blood insulin. A general effect of treatment was observed on the HOMA-IR index, with an 81% reduction in CR animals and 53% in RSV animals after 33 months of treatment compared to CTL. Chronic CR and dietary supplementation with RSV affected insulin sensitivity by improving the glucose tolerance of animals without disturbing their baseline insulin secretion. These results suggest that both CR and RSV have beneficial effects on metabolic alterations, although these effects are different in amplitude between the two anti-aging treatments and potentially rely on different metabolic changes

β-Adrenoreceptor Stimulation Mediates Reconsolidation of Social Reward-Related Memories

In recent years, the notion that consolidated memories become transiently unstable after retrieval and require reconsolidation to persist for later use has received strong experimental support. To date, the majority of studies on reconsolidation have focused on memories of negative emotions, while the dynamics of positive memories have been less well studied. Social play, the most characteristic social behavior displayed by young mammals, is important for social and cognitive development. It has strong rewarding properties, illustrated by the fact that it can induce conditioned place preference (CPP). In order to understand the dynamics of positive social memories, we evaluated the effect of propranolol, a β-adrenoreceptor antagonist known to influence a variety of memory processes, on acquisition, consolidation, retrieval and reconsolidation of social play-induced CPP in adolescent rats.Systemic treatment with propranolol, immediately before or after a CPP test (i.e. retrieval session), attenuated CPP 24 h later. Following extinction, CPP could be reinstated in saline--but not in propranolol-treated rats, indicating that propranolol treatment had persistently disrupted the CPP memory trace. Propranolol did not affect social play-induced CPP in the absence of memory retrieval or when administered 1 h or 6 h after retrieval. Furthermore, propranolol did not affect acquisition, consolidation or retrieval of social play-induced CPP.We conclude that β-adrenergic neurotransmission selectively mediates the reconsolidation, but not other processes involved in the storage and stability of social reward-related memories in adolescent rats. These data support the notion that consolidation and reconsolidation of social reward-related memories in adolescent rats rely on distinct neural mechanisms

Influence of the allotropic beta to alpha transformation and of oxygen on the distribution of plutonium in Zr-Pu and Ti-Pu dilute alloys

Ti-Pu, Zr-Pu and Ti-U alloys, annealed above the transformation point, can show major segregation after cooling. The segregations increase with oxygen content. Annealing at high temperatures followed by severe quenching can cause them to disappear. (7 refs)

Les nouveaux combustibles pour réacteurs à neutrons rapides

Les études sur le combustible des Réacteurs à Neutrons Rapides (RNR) explorent, depuis 1990, différentes options destinées à la gestion du plutonium et des actinides mineurs principalement dans le cadre des programmes CAPRA et SPIN. De nouveaux types de combustibles sont ainsi considérés et les solutions prises en compte pour ces applications concernent le choix du matériau combustible lui-même mais aussi la conception de l'aiguille et de l'assemblage combustible (notion d'hétérogénéité faisant appel à l'introduction de matériaux nouveaux inertes ou modérateurs). Néanmoins, les objectifs filière comme la possibilité d'atteindre de forts taux de combustion (économie) et la nécessité de travailler avec des matériaux de structure capables de supporter de très fortes doses restent d'actualité. Aujourd'hui, un important programme d'irradiation avec toutes ses activités connexes (fabrications, caractérisations, examens et études de retraitement) est en place. Il est traité dans le cadre de nombreuses collaborations internationales et se déroule dans différents réacteurs français et étrangers. On attend un retour significatif de ce programme vers 2003-2005

Origine et développement du combustible Uranium-Molybdène (U-Mo)

Historiquement, la plupart des réacteurs expérimentaux, en particulier les Réacteurs de Test et de Recherche, producteurs de hauts flux neutroniques, ont utilisé du combustible métallique à haut enrichissement en U235 (>90%). La politique actuelle est de plafonner l'enrichissement en U235 à 20% (objectif de non-prolifération). Après une première génération de combustible enrichi à 19.75% en U235 de type siliciure non retraitable, un consensus s'est dégagé au niveau international autour d'une nouvelle génération de combustible enrichi à 19.75% en U235, le combustible U-Mo (uranium - molybdène). Ce combustible permet de maintenir, voire d'améliorer, les performances actuelles des réacteurs tout en garantissant une fin de cycle acceptable (combustible retraitable). CEA, COGEMA, CERCA, FRAMATOME et TECHNICATOME ont regroupé leurs moyens techniques, financiers et leur savoir-faire pour développer en commun ce nouveau combustible U-Mo. Il est destiné aux réacteurs existants déjà convertis ou devant se convertir à l'uranium faiblement enrichi (en France, en Allemagne, au Japon, en Suède, ...) ainsi qu'aux nouveaux réacteurs tels que le RJH en France ou RRR en Australie. Ce programme de R& D démarré en 1999 est conduit en cohérence avec les travaux réalisés aux USA par l'Argonne National Laboratory. Compte tenu de la nécessité impérieuse pour les réacteurs de disposer en 2006 de ce nouveau combustible, seul à offrir une véritable solution de fin de cycle, l'objectif du groupe U-Mo français est de terminer la R& D et la qualification du combustible en 2005