In the field of gamma-ray astronomy, irregular and noisy datasets make difficult the characterization of light-curve features in terms of statistical significance while properly accounting for trial factors associated with the search for variability at different times and over different timescales. In order to address these difficulties, we propose a method based on the Haar wavelet decomposition of the data. It allows statistical characterization of possible variability, embedded in a white noise background, in terms of a confidence level. The method is applied to artificially generated data for characterization as well as to the the very high energy M87 light curve recorded with VERITAS in 2008 which serves here as a realistic application example.

La decouverte de l'operon lactose a aussi ete celle d'un nouveau type de genes: les regulateurs. Ceux-ci codent principalement des elements des voies de signalisation intercellulaire et des facteurs de transcription. Ils ont aussi un role cle dans le developpement embryonnaire, en coordonnant l'organisation pluricellulaire de l'embryon et la mise en place des differents organes, au bon moment et au bon endroit.

The X-ray binary LSI + 61°303 consisting of a main-sequence Be star and a compact object has been detected in the TeV range with MAGIC and VERITAS, and showed a clear intensity modulation as a function of the orbital phase. We describe a gamma-ray attenuation model and apply it to this system. Our first result is that interaction of high energy photons with the background radiation produced by the main-sequence star alone does not account for the observed modulation. We then include interactions between very high energy radiation and matter and are able to constrain fundamental parameters of the system such as the mass of the compact object and the density of circumstellar matter around the Be star. In our analysis of the TeV data, we find that the compact object has mass M2 > 2.5 M☉ at the 99% confidence level, implying it is most likely a black hole. However, we find a column density which conflicts with results from X-ray observations, suggesting that attenuation may not play an important role in the modulation.

The formation of peroxyacids by the reaction of a persalt (sodium percarbonate, sodium perborate,...) with an initiator (TAED, TAGU, NOBS, ISNOBS, PAG, acylsugars) has been developed. The reactivity of these peroxyacids generated "in situ" has been studied in the destruction of paraoxon (0,0-diethyl O-paranitrophenylphosphate) with some long chain tetraalkylammonium salts.

The formation of peroxyacids by the reaction of a persalt (sodium percarbonate, sodium perborate,…) with an initiator (TAED, TAGU, NOBS, ISNOBS, PAG, acylsugars) has been developed. The reactivity of these peroxyacids generated “in situ” has been studied in the destruction of paraoxon (0,0-diethyl O-paranitrophenylphosphate) with some long chain tetraalkylammonium salts.

Some complexed stable hydrogen peroxides (percarbonates, perhydrol, DABCO,2 H 2 O 2 ) have been studied in the destruction of paraoxon (O,O-diethyl paranitrophenylphosphate) and PhCH 2 CH 2 SCH 2 CH 2 CI. The reaction goes to completion in a short time specially in the presence of long chain tetraalkyl ammonium salts. With other peroxides (alkyl or arylhydroperoxides, bis-trimethylsilyl- or bis-triethylgermylperoxides) the reaction is slower.

A new and efficient method for oxidising sulfides selectively to sulfoxides has been developed with atmospheric oxygen, in the presence of isobutyraldehyde and catalysed by Ni-II complexes such as bis[1,3-bis-(p-methoxyphenyl)-1,3-propanedionato]nickel, [Ni(dmp)(2)], and bis[acetylacetonato]nickel, [Ni(acac)(2)].

Some complexed stable hydrogen peroxides (percarbonates, perhydrol, DABCO,2 H2O2) have been studied in the destruction of paraoxon (O,O-diethyl paranitrophenylphosphate) and PhCH2CH2SCH2CH2Cl. The reaction goes to completion in a short time specially in the presence of long chain tetraalkyl ammonium salts. With other peroxides (alkyl or arylhydroperoxides, bis-trimethylsilyl- or bis-triethylgermylperoxides) the reaction is slower.