In flight performance and first results of FREGATE

The gamma-ray detector of HETE-2, called FREGATE, has been designed to detect gamma-ray bursts in the energy range [6-400] keV. Its main task is to alert the other instruments of the occurrence of a gamma-ray burst (GRB) and to provide the spectral coverage of the GRB prompt emission in hard X-rays and soft gamma-rays. FREGATE was switched on on October 16, 2000, one week after the successful launch of HETE-2, and has been continuously working since then. We describe here the main characteristics of the instrument, its in-flight performance and we briefly discuss the first GRB observations.Comment: Invited lecture at the Woods Hole 2001 GRB Conference, 8 pages, 15 figure

Development of a modular CdTe detector plane for gamma-ray burst detection below 100 keV

We report on the development of an innovative CdTe detector plane (DPIX) optimized for the detection and localization of gamma-ray bursts in the X-ray band (below 100 keV). DPIX is part of an R&D program funded by the French Space Agency (CNES). DPIX builds upon the heritage of the ISGRI instrument, currently operating with great success on the ESA INTEGRAL mission. DPIX is an assembly of 200 elementary modules (XRDPIX) equipped with 32 CdTe Schottky detectors (4x4 mm2, 1 mm thickness) produced by ACRORAD Co. LTD. in Japan. These detectors offer good energy response up to 100 keV. Each XRDPIX is readout by the very low noise front-end electronics chip IDeF-X, currently under development at CEA/DSM/DAPNIA. In this paper, we describe the design of XRDPIX, the main features of the IDeF-X chip, and will present preliminary results of the reading out of one CdTe Schottky detector by the IDeF-X V1.0 chip. A low-energy threshold around 2.7 keV has been measured. This is to be compared with the 12-15 keV threshold of the ISGRI-INTEGRAL and BAT-SWIFT instruments, which both use similar detector material.Comment: 5 pages, 4 figures in color, Advances in Space Research, COSPAR meeting, Beijing (2006

Continuous cerebroventricular administration of dopamine: A new treatment for severe dyskinesia in Parkinson’s disease?

In Parkinson’s disease (PD) depletion of dopamine in the nigro-striatal pathway is a main pathological hallmark that requires continuous and focal restoration. Current predominant treatment with intermittent oral administration of its precursor, Levodopa (l-dopa), remains the gold standard but pharmacological drawbacks trigger motor fluctuations and dyskinesia. Continuous intracerebroventricular (i.c.v.) administration of dopamine previously failed as a therapy because of an inability to resolve the accelerated dopamine oxidation and tachyphylaxia. We aim to overcome prior challenges by demonstrating treatment feasibility and efficacy of continuous i.c.v. of dopamine close to the striatum. Dopamine prepared either anaerobically (A-dopamine) or aerobically (O-dopamine) in the presence or absence of a conservator (sodium metabisulfite, SMBS) was assessed upon acute MPTP and chronic 6-OHDA lesioning and compared to peripheral l-dopa treatment. A-dopamine restored motor function and induced a dose dependent increase of nigro-striatal tyrosine hydroxylase positive neurons in mice after 7 days of MPTP insult that was not evident with either O-dopamine or l-dopa. In the 6-OHDA rat model, continuous circadian i.c.v. injection of A-dopamine over 30 days also improved motor activity without occurrence of tachyphylaxia. This safety profile was highly favorable as A-dopamine did not induce dyskinesia or behavioral sensitization as observed with peripheral l-dopa treatment. Indicative of a new therapeutic strategy for patients suffering from l-dopa related complications with dyskinesia, continuous i.c.v. of A-dopamine has greater efficacy in mediating motor impairment over a large therapeutic index without inducing dyskinesia and tachyphylaxia

Improvement of the T-cell response to a non-immunogenic peptide by its tandem association with a highly efficient T-helper peptide.

International audienceThe 45-69 peptide, an helper T-cell epitope derived from HIV nef protein, is strongly immunogenic. A T-cell proliferative response was observed following immunization of Lou/M rats with 45-69 peptide administered in low dose and without any adjuvant. It is already known that the T-cell response to the 115-131 peptide of Sm28GST antigen, a protein of the parasite Schistosoma mansoni, requires the presence of a carrier or the use of peptidic constructs. We demonstrate here that a T-cell response against the 115-131 peptide can be obtained in the absence of adjuvant using peptidic constructs (115-45 and 45-115 peptides) resulting from tandem synthesis of 115-131 and 45-69 peptides. A covalent association of both peptides is necessary, since the co-injection of 45-69 and 115-131 peptides is not sufficient to induce a detectable anti-115-131 T-cell response. The mutual orientation between the respective tandem peptides (45-115 and 115-45) is critical for the T-cell response. These peptidic constructs possess distinct properties of antigenicity and immunogenicity but both allowed to reveal the existence of a 115-131 specific T-cell response normally undetectable using 115-131 peptide alone. This immunopharmacological approach should be useful in the rational design and construction of vaccines.The 45-69 peptide, an helper T-cell epitope derived from HIV nef protein, is strongly immunogenic. A T-cell proliferative response was observed following immunization of Lou/M rats with 45-69 peptide administered in low dose and without any adjuvant. It is already known that the T-cell response to the 115-131 peptide of Sm28GST antigen, a protein of the parasite Schistosoma mansoni, requires the presence of a carrier or the use of peptidic constructs. We demonstrate here that a T-cell response against the 115-131 peptide can be obtained in the absence of adjuvant using peptidic constructs (115-45 and 45-115 peptides) resulting from tandem synthesis of 115-131 and 45-69 peptides. A covalent association of both peptides is necessary, since the co-injection of 45-69 and 115-131 peptides is not sufficient to induce a detectable anti-115-131 T-cell response. The mutual orientation between the respective tandem peptides (45-115 and 115-45) is critical for the T-cell response. These peptidic constructs possess distinct properties of antigenicity and immunogenicity but both allowed to reveal the existence of a 115-131 specific T-cell response normally undetectable using 115-131 peptide alone. This immunopharmacological approach should be useful in the rational design and construction of vaccines

Security properties of typed applets

This paper formalizes the folklore result that strongly-typed applets are more secure than untyped ones. We formulate and prove several security properties that all well-typed applets possess, and identify sufficient conditions for the applet execution environment to be safe, such as procedural encapsulation, type abstraction, and systematic type-based placement of run-time checks. These results are a first step towards formal techniques for developing and validating safe execution environments for applets