RESUMO
EUSO-Balloon is a pathfinder for JEM-EUSO, the mission concept of a spaceborne observatory which is designed to observe Ultra-High Energy Cosmic Ray (UHECR)-induced Extensive Air Showers (EAS) by detecting their UltraViolet (UV) light tracks "from above." On August 25, 2014, EUSO-Balloon was launched from Timmins Stratospheric Balloon Base (Ontario, Canada) by the balloon division of the French Space Agency CNES. After reaching a floating altitude of 38 km, EUSO-Balloon imaged the UV light in the wavelength range â¼290-500 nm for more than 5 hours using the key technologies of JEM-EUSO. The flight allowed a good understanding of the performance of the detector to be developed, giving insights into possible improvements to be applied to future missions. A detailed measurement of the photoelectron counts in different atmospheric and ground conditions was achieved. By means of the simulation of the instrument response and by assuming atmospheric models, the absolute intensity of diffuse light was estimated. The instrument detected hundreds of laser tracks with similar characteristics to EASs shot by a helicopter flying underneath. These are the first recorded laser tracks measured from a fluorescence detector looking down on the atmosphere. The reconstruction of the direction of the laser tracks was performed. In this work, a review of the main results obtained by EUSO-Balloon is presented as well as implications for future space-based observations of UHECRs.
RESUMO
The characterization of a PET detector head based on continuous LYSO crystals and silicon photomultiplier (SiPM) arrays as photodetectors has been carried out for its use in the development of a small animal PET prototype. The detector heads are composed of a continuous crystal and a SiPM matrix with 64 pixels in a common substrate, fabricated specifically for this project. Three crystals of 12 mm × 12 mm × 5 mm size with different types of painting have been tested: white, black and black on the sides but white on the back of the crystal. The best energy resolution, obtained with the white crystal, is 16% FWHM. The detector response is linear up to 1275 keV. Tests with different position determination algorithms have been carried out with the three crystals. The spatial resolution obtained with the center of gravity algorithm is around 0.9 mm FWHM for the three crystals. As expected, the use of this algorithm results in the displacement of the reconstructed position toward the center of the crystal, more pronounced in the case of the white crystal. A maximum likelihood algorithm has been tested that can reconstruct correctly the interaction position of the photons also in the case of the white crystal.
Assuntos
Luz , Tomografia por Emissão de Pósitrons/instrumentação , Silício/química , Animais , Gravitação , Funções Verossimilhança , Fatores de TempoRESUMO
OBJECTIVE: Intrafamilial transmission of hepatitis C virus in human immunodeficiency virus and hepatitis C virus co-infections is not well documented. This cross-sectional study evaluated the transmission of hepatitis C virus in the sexual partners of hepatitis C virus and human immunodeficiency virus co-infected patients. METHODS: Hemophiliacs and transfused hepatitis C virus and human immunodeficiency virus co-infected patients who were being seen in three French university hospitals, and their sexual partners were studied by a face-to-face interview using an epidemiological questionnaire and by biological tests: antibodies against hepatitis C virus, hepatitis C virus RNA, and ALT activity. RESULT: Fifty-two subjects were included: 26 cases and their 26 sexual partners. Three sexual partners (11.5 %) had anti-hepatitis C virus antibodies, two of whom had an undetermined RIBA test. All three had a risk factor for hepatitis C virus infection (transfusion, intra-muscular injections with re-usable needles). Two of these three partners were also human immunodeficiency virus antibody positive. Hepatitis C virus RNA was negative in all sexual partners. CONCLUSION: This study provides evidence of a low prevalence of anti-hepatitis C virus antibodies in sexual partners of hepatitis C virus and human immunodeficiency virus co-infected patients. It does not support intra-familial transmission of hepatitis C virus.
