Spectral analysis of 50 GRBs detected by HETE-2

FREGATE, the gamma-ray detector of HETE-2 is entirely dedicated to the study of GRBs. Its main characteristic is its broad energy range, from 7 keV to 400 keV. This energy range can be further extended down to 2 keV using the data from the WXM, the X-ray detector of HETE-2. Such a large energy range allows to study in details the prompt emission of GRBs, determining with a high precision their spectral parameters. Moreover, because this energy range extends at low energies, the sample of GRBs detected by both FREGATE and WXM contains a significant fraction of X-Ray Rich GRBs and X-Ray Flashes. We present here the distributions of the spectral parameters mesured for the time integrated spectra of 50 GRBs. We put emphasis on the distribution of the low energy spectral index alpha. Because FREGATE and WXM detected all classes of GRBs, we also discuss the connection between GRBs, X-Ray Rich GRBs and X-Ray Flashes.Comment: 4 pages aipTEX, contribution to the 2003 GRB Conference, held at Santa Fe,N

Les officialités normandes et la lutte contre les mariages clandestins à la fin du Moyen Age

Il s’agit de préciser ce que les tribunaux poursuivent au titre de la lutte contre lesmariages informels, ce que cela révèle du rôle que la cour diocésaine entend jouer dans le contrôle du processus matrimonial, et de quelle manière les officialités ont pu profiter de la définition in fine extensive de la clandestinité pour mettre au point des instruments de renforcement de l’autorité diocésaine (notamment par le contrôle de la mobilité matrimoniale). De nombreuses infractions dénoncées concernent les promesses de mariage suivies de relations charnelles qui font présumer un consentement de présent. Au stade de l’échange des paroles de présent, les mariages clandestins mis à l’amende sont des mariages marqués par un déficit de preuves, ou conclus sans publication préalable des bans, célébrés dans une autre paroisse que la « propre paroisse » des époux, ou sans respect de formes réglementaires imposées par les évêques, notamment pour contrôler les mariages des extradiocésains, par la présentation de lettres testimoniales ou de dispense de bans, dont on constate la standardisation croissante à la fin du XVe siècle. Au nom de la lutte contre ces irrégularités matrimoniales, les autorités diocésaines rouennaises ont renforcé et élargi toujours plus leurs exigences réglementaires. Les candidats au mariage en paient le prix : pour faire régulariser a posteriori leur union ou pour s’acquitter de l’amende due, mais aussi pour obtenir les certifications nécessaires afin de se prémunir contre toute irrégularité. Les célébrants en paient également le prix quand ils pensent pouvoir se contenter de lettres certificatoires de publication de bans délivrées ailleurs que dans la juridiction rouennaise. Les officialités, comme instance de mise en ordre matrimonial, permettent ainsi aux autorités diocésaines de s’imposer comme gardiennes du salut des couples tout en préservant et renforçant leur assise juridictionnelle

Les mariages clandestins: impasse disciplinaire, scandale ou moteur de la réflexion doctrinale?

The history of the formalization of marriage law in the Latin medieval West is very much like a series of normative tensions. Although the conflicts of norms cannot be restricted to theological and legal controversies, their interest lies in the fact that they sometimes gave rise to the expression of contradictory norms, depending on the forum at stake. It was more particularly the case when it came to the question of settling the moral and judiciary issues in connexion with the hierarchical status of clandestine marriages and that of public ones, or the one of a “sexual intercourse followed by words of future” and that of a marriage contracted by “words of present”. Which of these processes guaranteed a « true » marriage ?  And according to which normative references ? The different solutions provided by canonical doctrine, theology, the manuals for parish priests and confessors or even synodal statutes enable us to assess the different goals of the clerics concerned by matrimonial issues. Much is at stake, because what is concerned is the salvation of the laity and the balance of the whole society. These normative tensions sometimes led to conceptual and lexical evolutions, but they also entailed certain forms of competition that could undermine the usual means of social regulation, which the actors of matrimonial could sometimes take advantage of

Observation and implications of the Epeak - Eiso correlation in Gamma-Ray Bursts

The availability of a few dozen GRB redshifts now allows studies of the intrinsic properties of these high energy transients. Amati et al. recently discovered a correlation between Epeak, the intrinsic peak energy of the $\nu f \nu$ spectrum, and Eiso, the isotropic equivalent energy radiated by the source. Lamb et al. have shown that HETE-2 data confirm and extend this correlation. We discuss here one of the consequences of this correlation: the existence of a 'spectral standard candle', which can be used to construct a simple redshift indicator for GRBs.Comment: Proceedings of the GRB 2003 Conference in SantaFe, 5 pages, 4 figure

On the nature of X-Ray Flashes

We discuss the origin of X-Ray Flashes (XRFs), a recently discovered class of Gamma-Ray Bursts (GRBs). Using a simplified model for internal shocks we check if XRFs can be intrinsically soft due to some specific values of the parameters describing the relativistic outflow emerging from the central engine. We generate a large number of synthetic events and find that XRFs are obtained when the contrast Gamma_max/Gamma_min of the Lorentz factor distribution is small while the average Lorentz factor Gamma is large. A few XRFs may be GRBs at large redshifts but we exclude this possibility for the bulk of the population. If outflows with a small contrast are commonly produced, even a large population of XRFs could be explained. If conversely the Lorentz factor distribution within the wind is broad, one should then rely on extrinsic causes, such as viewing angle effects or high redshift.Comment: 9 pages, 8 figures, to appear in A&

Charge dynamics and spin blockade in a hybrid double quantum dot in silicon

Electron spin qubits in silicon, whether in quantum dots or in donor atoms, have long been considered attractive qubits for the implementation of a quantum computer due to the semiconductor vacuum character of silicon and its compatibility with the microelectronics industry. While donor electron spins in silicon provide extremely long coherence times and access to the nuclear spin via the hyperfine interaction, quantum dots have the complementary advantages of fast electrical operations, tunability and scalability. Here we present an approach to a novel hybrid double quantum dot by coupling a donor to a lithographically patterned artificial atom. Using gate-based rf reflectometry, we probe the charge stability of this double quantum dot system and the variation of quantum capacitance at the interdot charge transition. Using microwave spectroscopy, we find a tunnel coupling of 2.7 GHz and characterise the charge dynamics, which reveals a charge T2* of 200 ps and a relaxation time T1 of 100 ns. Additionally, we demonstrate spin blockade at the inderdot transition, opening up the possibility to operate this coupled system as a singlet-triplet qubit or to transfer a coherent spin state between the quantum dot and the donor electron and nucleus.Comment: 6 pages, 4 figures, supplementary information (3 pages, 4 figures

Rivers groins along the Armoricain Loire : river responses and local resident reactions. A sociogeographical landscape reading as a complement for ecological engineering

International audienc

Bioceramic fabrics improve quiet standing posture and handstand stability in expert gymnasts

Bioceramic fabrics have been claimed to improve blood circulation, thermoregulation and muscle relaxation, thereby also improving muscular activity. Here we tested whether bioceramic fabrics have an effect on postural control and contribute to improve postural stability. In Experiment 1, we tested whether bioceramic fabrics contribute to reduce body-sway when maintaining standard standing posture. In Experiment 2, we measured the effect of bioceramic fabrics on body-sway when maintaining a more instable posture, namely a handstand hold. For both experiments, postural oscillations were measured using a force platform with four strain gauges that recorded the displacements of the center of pressure (CoP) in the horizontal plane. In half of the trials, the participants wore a full-body second skin suit containing a bioceramic layer. In the other half of the trials, they wore a ‘placebo’ second skin suit that had the same cut, appearance and elasticity as the bioceramic suit but did not contain the bioceramic layer. In both experiments, the surface of displacement of the CoP was significantly smaller when participants were wearing the bioceramic suit than when they were wearing the placebo suit. The results suggest that bioceramic fabrics do have an effect on postural control and improve postural stability

Electric-field tuning of the valley splitting in silicon corner dots

We perform an excited state spectroscopy analysis of a silicon corner dot in a nanowire field-effect transistor to assess the electric field tunability of the valley splitting. First, we demonstrate a back-gate-controlled transition between a single quantum dot and a double quantum dot in parallel that allows tuning the device in to corner dot formation. We find a linear dependence of the valley splitting on back-gate voltage, from $880~\mu \text{eV}$ to $610~\mu \text{eV}$ with a slope of $-45\pm 3~\mu \text{eV/V}$ (or equivalently a slope of $-48\pm 3~\mu \text{eV/(MV/m)}$ with respect to the effective field). The experimental results are backed up by tight-binding simulations that include the effect of surface roughness, remote charges in the gate stack and discrete dopants in the channel. Our results demonstrate a way to electrically tune the valley splitting in silicon-on-insulator-based quantum dots, a requirement to achieve all-electrical manipulation of silicon spin qubits.Comment: 5 pages, 3 figures. In this version: Discussion of model expanded; Fig. 3 updated; Refs. added (15, 22, 32, 34, 35, 36, 37