Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA

T-REX Operating Unit 3

OU3 is one of the six Operating Units of the Progetto Premiale T-REX. It is focused on the development of adaptive optics instrumentation for the European Extremely Large Telescope. The main activities of OU3 are the MAORY adaptive optics module, the MICADO infrared camera, the characterisation and forecast of atmospheric parameters for the E-ELT site and general developments for future adaptive optics systems. <P /

Optimizing Citrate Combustion Synthesis of A-Site-Deficient La,Mn-Based Perovskites: Application for Catalytic CH4 Combustion in Stoichiometric Conditions

LaMnO3-based perovskites are widely recognized as promising catalysts for several oxidation reactions, but the final physicochemical and catalytic properties can be greatly influenced by the adopted synthesis procedure. In this work, a series of A-site-deficient perovskites of composition La0.8MnO3 and La0.8Mn0.9B0.1O3 (B = Ni, Cu) were prepared through the citrate combustion route with variations in two synthesis parameters: a citric acid/metal cations molar ratio (CA/M) of either 1.1 or 1.5 and either acidic (given by HNO3 + citric acid) or neutral (after NH3 addition) pH of the precursor solution. The obtained samples were characterized by XRD, H2-TPR, O2-TPD, N2 physisorption, SEM-EDX and XPS. Acidic pH coupled with a CA/M ratio of 1.1 clearly emerged superior among all the other combinations of the two parameters, resulting in smaller crystallite size, higher surface area and porosity, enhanced Mn4+ reducibility and the ability to release oxygen species; these features were even further improved by B-site substitution with 10 mol% Ni and Cu cations. The synthesized catalysts were tested in CH4 oxidation to CO2 under stoichiometric O2, confirming the great superiority of samples prepared in acidic pH with a CA/M ratio of 1.1. Ni and Cu doping had a beneficial effect on catalytic activity, which, however, was more evident for less optimized perovskites (acidic pH and CA/M ratio of 1.5), without significance differences among the two dopants

N2 solar activation: ammonia as a hydrogen vector for energy storage

From the plethora of energy-intensive synthetic processes, ammonia production has a particularly negative impact due to the high-energy consumption caused by the Haber-Bosch process and the high greenhouse gas (GHG) emission rate. Thus, new and effective ways to activate N-2 and synthesise NH3 are crucial to reduce production costs and the anthropogenic footprint derived from the current harsh reaction conditions. In this study, two-dimensional materials have been employed in the photoactivation of nitrogen in an aqueous medium; M-I(ii)M-II(iii) (with M-I = Cu or CuNi, and M-II = Cr or Al) layered double hydroxides have been synthesised using a simple, economical and scalable co-precipitation/filtration method. The structural and functional properties were systematically investigated by XRD, SEM, TPR and BET; the results indicate that the prepared LDHs were successfully synthesised, possess high surface areas and, in the case of CuAl LDH, the material showed a nanoplate-like structure, thus confirming the two-dimensional nature of this class of catalyst. The N-2 fixation performances were evaluated using a scalable, cost-effective and low-energy-consuming setup; from the catalytic tests, a NH3 production rate of 99 mu mol g(-1) h(-1) was observed, demonstrating LDHs' high potential and the scalability of the overall process

Aerosol-cloud interactions at the four candidate sites of the ANAtOLIA project

International audienceANAtOLIA (Atmospheric monitoring to Assess the availability of Optical Links through the Atmosphere) is a European Space Agency project aimed at selecting sites for optical communication in the atmosphere. The main monitored parameters are cloud cover, aerosol in relation to atmospheric turbulence aimed at monitoring and forecasting the influence of aerosol and cloud cover in reducing optical communication through the atmosphere in selected sites by ESA. In this work, a novel algorithm that uses both the Pearson correlation coefficient and Fourier analysis is used to assess such influences. Aerosol and cloud cover data are obtained from ground stations and satellite over Calern (France), Catania (Italy), Cebreros (Spain), and Lisbon (Portugal). The novel algorithm provides a preliminary long-, medium-, and short-term aerosol-cloud interaction for these four candidate sites, obtaining respectively the variability, the seasonal, and hourly trend of the aerosol concentration; the main medium-term periodicities of aerosols as clouds precursors; the short-term correlation between morning-afternoon aerosol concentration. The use of aerosols as a precursor parameter of cloud cover through a Fourier analysis, makes the algorithm versatile and usable for all sites of optical communication and astronomical importance in which optical transparency is a fundamental requirement, and therefore it is a potential tool to be developed to implement forecasting models

Abscesso subdural ao nível da cauda equina: relato de um caso

É relatada a observação de um paciente de 42 anos, com paraplegia flácida devida a abscesso subdural ao nível da cauda equina. É realçada a pobreza de alterações sensitivas e esfincterianas neste caso e enfatizada a importância da cirurgia para obtenção de bons resultados

ANAtOLIA : a mobile station for site availability characterization for optical communications links

The Atmospheric moNitoring to Assess the availability of Optical LInks through the Atmosphere (ANAtOLIA) is a station developed in the framework of a project funded by the European Space Agency which aims to ground- sites selection and assess their availabilities for optical links through the atmosphere. In addition to cloud cover, space-to-ground optical communications are limited by aerosols and atmospheric turbulence. Therefore, we are developing in the framework of the ANAtOLIA project, an innovative and efficiency instrumentation and studies to specify, accurately measure, analyze, characterize, and ultimately predict critical atmospheric parameters for the purposes of the selection of the Optical Ground Station (OGS) sites and the evaluation of their availability. The main objectives of ANAtOLIA project are to design, manufacture, procure and assembly a self-standing and autonomous ground support equipment, comprising cloud, aerosol and turbulence monitoring to deliver precise measurements of the atmosphere transmission. Then, to install and commission of these atmosphere monitors at selected ground locations in ESA member states or in their vicinity and to record continuously local cloud, aerosol information and atmospheric turbulence conditions for 24 months. The last objective is to correlate these local ground measurements with data available from other sources of atmospheric conditions. The main goal of these correlations is to improve knowledge of the optical link availability for selected OGS locations and to carry out a long-term validation of the optical link availability prediction methods. ANAtOLIA is a compact 24h mobile station consisting of the Generalized Monitor of Turbulence (GMT), the R ́euniwatt Sky Insight camera and the Cimel photometer CE318-T