202 research outputs found
Emploi de la méthode des fonctions de décision pour l'identification des images géométriques sur les clichés fournis par les spectromètres magnétiques à étincelles
Comprehensive analysis of draft genomes of two closely related pseudomonas syringae phylogroup 2b strains infecting mono- and dicotyledon host plants
Comparison of the prophage region in Pseudomonas syringae strain SM (A) with the corresponding regions in strains 1845 (B) and 2507 (C) using MAUVE software (Darling et al. 2010). (PNG 2118 kb
General description of a geometrical reconstruction program for large chambers ("1-6" version)
Primary Sequences of Protein-Like Copolymers: Levy Flight Type Long Range Correlations
We consider the statistical properties of primary sequences of two-letter HP
copolymers (H for hydrophobic and P for polar) designed to have water soluble
globular conformations with H monomers shielded from water inside the shell of
P monomers. We show, both by computer simulations and by exact analytical
calculation, that for large globules and flexible polymers such sequences
exhibit long-range correlations which can be described by Levy-flight
statistics.Comment: 4 pages, including 2 figures; several references added, some
formulations improve
The Megapixel EBCCD: a high-resolution imaging tube sensitive to single photons
A hybrid image-intensifier tube, suitable for extremely low-light imaging, has been tested. This device is based on an Electron-Bombarded CCD chip (EBCCD) with sensitive pixe ls. The tube, which has a photocathode diameter of 40 mm, is gateable and zoomable, with an image magnification varying from 0.62 to 1.3. The high gain (about 4000 collected electrons per photo electron at the operational voltage of 15 kV) and the relatively low noise (180 electrons per pixel at 10 MHz pixel-readout frequency), allows single-photoelectron signals to be separated from n oise with a signal-to-noise ratio greater than 10. By applying an appropriate threshold on the signal amplitude, the background can almost be eliminated, with a loss of few percent in single-ph otoelectron counting. High inner gain, low noise, single-photoelectron sensitivity, and high spatial resolution make the EBCCD imaging tube a unique device, attractive for many applications in h igh-energy physics, astrophysics, biomedical diagnostics
A high-resolution tracking hodoscope based on capillary layers filled with liquid scintillator
Results are given on tests of a high-resolution tracking hodoscope based on layers of \hbox{26-m-bore} glass capillaries filled with organic liquid scintillator (1-methylnaphthalene doped with R39). The detector prototype consisted of three 2-mm-thick parallel layers, with surface areas of ~cm. The layers had a centre-to-centre spacing of 6~mm, and were read by an optoelectronic chain comprising two electrostatically focused image intensifiers and an Electron-Bombarded Charge-Coupled Device (EBCCD). Tracks of cosmic-ray particles were recorded and analysed. The observed hit density was 6.6~hits/mm for particles crossing the layers perpendicularly, at a distance of 1~cm from the capillaries' readout end, and 4.2~hits/mm for particles at a distance of 20~cm. A track segment reconstructed in a single layer had an rms residual of ~20~m, and allowed determination of the track position in a neighbouring layer with a precision of ~170~m. This latter value corresponded to an rms angular resolution per layer of about 30~mrad. A comparison is made between capillary layers and silicon microstrip planes
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