Infection levels of proteocephalidean cestodes in Cichla piquiti (Osteichthyes: Cichlidae) of the Volta Grande Reservoir, Minas Gerais, Brazil, relative to host body weight and gender

We evaluated the relationship between infection by proteocephalid cestodes and the sex and weight classes of tucunaré (Cichla piquiti) captured between August 1999 and June 2001 in the Volta Grande Reservoir, Minas Gerais, Brazil. A total of 96 fish, 75.9±9.3% males and 88.9±6.4% females, were parasitized by Proteocephalus macrophallus and P. microscopicus, with total mean intensities of 76.6±23.9 and 145.2±36.7, respectively, during this period. In the majority of the months analysed, males showed 71.4-100% prevalence of parasitism and females 80-100%. Although there was no significant difference, females showed a higher mean intensity of infection (145.2±36.7) than males (76.6±23.9). Fish weighing 300-800g showed a higher mean abundance of parasites (P<0.05) compared with the biggest specimens weighing 801-2750g. Analysing both males and females together, the greatest mean intensities of infection were found in October and December (P<0.05) independent of the year, which coincides with the months of highest rainfall. These results show that fish living in reservoirs may be more susceptible to intermediate hosts than those that live in river

Observations of Toroidal Coupling for Low-N Alfven Modes in the Tca Tokamak

The antenna structure in the TCA tokamak is phased to excite preferentially Alfven waves with known toroidal and poloidal wave numbers. Surprisingly, the loading spectrum includes both discrete and continuum modes with poloidal wave numbers incompatible with the antenna phasing. These additional modes, which are important for our heating experiments, can be attributed to linear mode coupling induced by the toroidicity of the plasma column, when we take into account ion-cyclotron effects

Facade Integration of Solar Thermal Collectors:A Breakthrough?

One main barrier to the acceptability of façade use of solar thermal collectors is their black appearance and the visibility of piping or absorber irregularities through the glazing. To facilitate façade integration, a project was set up to develop selective filters reflecting only a small part of the solar spectrum in the visible range while letting the rest of the radiation heat the absorber. These filters were successfully produced and, combined with a diffusing glass treatment, have achieved the desired masking effect with minor impact on the collector efficiency (less than 10%). Glasses of various colours combined with several diffusing finishing (acid etching, structured glass etc…) can be produced that are able to hide the absorber. Such glazings will allow the use of the same product both in front of façade areas equipped with solar absorbers (as collector external glass) and in front of the non exposed areas (as façade cladding), opening the way to a broad variety of active façade designs. The active elements can then be positioned at will on the exposed areas, and their quantity determined only by thermal needs. By freeing the dimension of the façade area that can be clad with this glazing from the thermally needed surface for collectors, a major step to help architects use solar thermal on facades has been taken

Sol-gel deposition of nanostructured low refractive index materials on solar collector glazing

Nanoporous SiO2 and nanocomposite MgF2:SiO2 coatings have been deposited by sol gel dip-coating in a particle-free atmosphere. The refractive index of the prepared nanostructured thin films is determined from spectrophotometric data. In both cases, significantly lower values than for compact SiO2 have been achieved. Highly transparent samples have been produced in a single dip-coating step followed by simple thermal annealing in air. Broad spectral transmittance maxima are observed exceeding values of 98.5% (nanoporous SiO2) and 99.5% (quaternary Mg:F:Si:O films). MgF2:SiO2 nanocomposite thin films can be expected to exhibit a higher aging stability than porous SiO2 films with respect to pore-filling by hydrocarbons and are therefore a promising alternative as well for single-layered anti reflection coatings as for multilayered coulored coatings on solar collector glazing