The Cherenkov Correlated Timing Detector: Beam Test Results from Quartz and Acrylic Bars

Several prototypes of a Cherenkov Correlated Timing (CCT) Detector have been tested at the KEK-PS test beam line. We describe the results for Cherenkov light yields and timing characteristics from quartz and acrylic bar prototypes. A Cherenkov angle resolution is found to be 15 mrad at a propagation distance of 100 cm with a 2 cm thick quartz bar prototype.Comment: Presented at the RICH95 workshop, Uppsala, Sweden, June/95. H. Kichimi corresponding author. 5 pages with 9 figures. LaTex source files and postscript figures compressed and uuencoded belo

Análisis económicos fundamentales en fertilizaciones de papa, algodón y maíz

17 P.Gracias al trabajo hecho en las diversas estaciones experimentales en América Central (1.5), se ha establecido, fuera de toda duda, que los fertilizantes son uno de los factores más importantes en el aumento del rendimiento en las cosecha

Superconducting Fault Current Limiter for Ship Grid Simulation and Demonstration

International audienceThe strong growth of electrical power on ships leads to modifications and optimizations of their electrical grid, from their architecture to their components. An emerging architecture is the dc grid, which outperforms the ac solution. Security and protection are two major concerns on a ship. Even with controllable static converters, fault currents may be very high. For security reasons there are in general a port grid and a starboard grid. They are not connected in normal operation: a fault (short-circuit) on one grid must have no influence on the other grid to avoid a total blackout. On the other side, a coupling between the two grids brings many advantages through mutualisation and a stronger grid. This coupling is possible using a superconducting fault current limiter (SCFCL). A SCFCL between the two ship grids appears as a promising solution to take benefit of the coupling under normal operation and the decoupling under a fault case. Simulations have been carried out using EMTP-RV to study the operation and the advantages of such SCFCL implementation, with consequences in terms of safety in addition to protection. These simulations show that the healthy grid does not nearly see the short-circuited one. The voltage of the dc bus only experiences a little transient drop (lower than 10%), whereas the ac voltage supplies for the propulsion motors are not affected at all. A demonstrator has been developed. It uses SuperOx REBCO pancakes. The rating is 500 A-800 V at 77 K using two 12-mm-wide tapes in parallel. The design of the demonstrator, of its SC element (design of the REBCO tape shunt) in particular and preliminary tests are presented in ac conditions but at temperatures higher than 77 K to fit the laboratory limited testing capacities

A novel poly-oxygenated flavone glucoside from aerial parts of the Brazilian plant Neoglaziovia variegata (Bromeliaceae)

Neoglaziovia variegata is endemic to northeastern Brazil. The drought resistant plant produces edible fruits and is used as a fibre plant by rural communities in the Caatinga region where a variety of products are made from the white, soft and flexible fibres. Extracts of N. variegata have been reported to be of low toxicity and to exhibit antinociceptive effect, photoprotective potential, antioxidant effect, gastroprotective effects and antibacterial effect against both Gram-positive and Gram-negative bacteria, however, the chemical constituents of this species are mainly unknown. The novel poly-oxygenated flavone glucoside 5,6,7,4’-tetrahydroxy-3’,5’-dimethoxy-flavone 7-O-b-glucopyranoside in addition to the rare poly-oxygenated flavone 5,4’-dihydroxy-6,7,3’-trimethoxyflavone 4’- O-b-glucopyranoside and the flavonol quercetin 3-O-(6’’-rhamnopyranosyl-bglucopyranoside) have been characterised from the leaves of N. variegata. 5,6,7,4’-tetrahydroxy-3’,5’-dimethoxy-flavone, which comprises the core structure of the novel compound, is a new flavonoid aglycone in nature. The structure determinations were based on extensive use of 2D NMR spectroscopic techniques and high-resolution mass spectrometry. Both substances exhibited toxicity towards MOLM-13 acute myeloid leukaemia cells

Ideas for underwater 3D sonar range sensing and environmental modeling

A 3D spatial grid for exploiting the range and direction information inherent in sonar range data is presented. Special attention is given to the realtime performance of this representation, i.e. it should be a feasible way of representing the 3D range data acquired by an operating AUV