Dusty Sources at the Galactic Center: The N- and Q-band view with VISIR

We present mid-infrared N- and Q-band photometry of the Galactic Center from images obtained with the mid-infrared camera VISIR at the ESO VLT in May 2004. The high resolution and sensitivity possible with VISIR enables us to investigate a total of over 60 point-like sources, an unprecedented number for the Galactic Center at these wavelengths. Combining these data with previous results at shorter wavelengths (Viehmann et al. 2005) enables us to construct SEDs covering the H- to Q-band regions of the spectrum, i.e. 1.6 to 19.5 $\mu$m. We find that the SEDs of certain types of Galactic Center sources show characteristic features. We can clearly distinguish between luminous Northern Arm bow-shock sources, lower luminosity bow-shock sources, hot stars, and cool stars. This characterization may help clarify the status of presently unclassified sources.Comment: 18 pages, 4 figures, 1 table, accepted for publication in the Astrophysical Journa

Comparative investigations of the biodurability of mineral fibers in the rat lung.

The biodurability of various glass fibers, rockwool, and ceramic fibers was examined in rat lungs and compared with natural mineral fibers. Experiments were based on studies that have shown that the biodurability of fibers is one of the essential factors of the carcinogenic potency of these materials. Sized fractions of fibers were instilled intratracheally into Wistar rats. The evenness of distribution of fibers in the lung was checked by scanning electron microscopy (SEM) or careful examination of the fiber suspension before treatment. After serial sacrifices up to 24 months after treatment, the fibers were analyzed by SEM following low temperature ashing of the lungs. Parameters measured included number of fibers, diameter, and length distribution at the various sacrifice dates, so that analyses could be made of the elimination kinetics of fibers from the lung in relation to fiber length (FL). Size selective plots of the fiber elimination correlated with fiber diameters enables the mechanism of the fiber elimination (dissolution, fiber breakage, physical clearance) to be interpreted. The half-time of fiber elimination from the lung ranges from about 10 days for wollastonite to more than 300 days for crocidolite. The biodurability of man-made vitreous fibers (MMVF) is between these values and is dependent on the chemical composition of the fibers and the diameter and length distribution. Results indicate that the in vivo durability of glass fibers is considerably longer than expected from extrapolation of published data on their in vitro dissolution rates

Respostas das plantas após diferentes distúrbios no Pantanal: estudo de caso de algumas forrageiras.

O conhecimento sobre a resposta das forrageiras aos distúrbios antrópicos e naturais é fundamental para auxiliar os tomadores de decisão na avaliação da condição de conservação e tendência das pastagens nativas ou no desenvolvimento de estratégias adequadas de manejo adaptativas. Este estudo teve como objetivo avaliar a resposta de algumas forrageiras nativas em relação a diferentes distúrbios antrópicos (pastejo e fogo) e naturais (seca e inundação) no Pantanal. Dentre as diversas espécies de plantas do Pantanal, foram escolhidas oito gramíneas e quatro espécies herbáceo-arbustivas. A resposta das plantas ao distúrbio foi classificada como: ?aumenta?, ?diminui? e/ou ?invade?. Observou-se que muitas das espécies podem apresentar aumento ou diminuição quando submetida ao mesmo distúrbio, pois a resposta depende da intensidade e duração do distúrbio, história da dinâmica da vegetação do local, época, ambiente e regime climático. Trabalhos desta natureza devem ser intensificados no Pantanal, envolvendo um maior número de espécies e distúrbios, de preferência com a utilização de parcelas fixas, juntamente com a participação da comunidade local. The knowledge of forage response following anthropogenic and natural disturbance is essential to make decisions making assess of rangeland conservation conditions and trends, or for the development of sound management strategies. The objective of this study was to evaluate the response of some native forage following anthropogenic disturbance (grazing and fire) and natural disturbance (drought and flood) in the Pantanal. Eight grasses and four shrub-herb were selected for this study. Plant response was classified as ?decreaser?, ?increaser? and/or ?invader? species. It was observed that several forages species can to increase or decrease following the same disturbances depending of the frequency, intensity and duration of the disturbance, history of the vegetation dynamic in the area, season, environment and climatical regime. Studies of this type should be intensified in the Pantanal and involve other plants species and disturbance, use fix plots and encourage the participation of the local community

Significance of durability of mineral fibers for their toxicity and carcinogenic potency in the abdominal cavity of rats in comparison with the low sensitivity of inhalation studies.

At the same time that carcinogenicity of very thin glass fibers after intrapleural and intraperitoneal (ip) administration was demonstrated (1,2) researchers found that gypsum fibers and HCI-leached chrysotile fibers were easily soluble in the peritoneal cavity. This led to the conclusion that the chemical composition of fibers was not responsible for the carcinogenesis but that the degree of carcinogenic potency of a fiber depended on the extent to which it retained its fibrous structure. A thin glass fiber with a low biodurability did not induce tumors after ip injection of a high dose, although the ip test had been criticized for being "overly sensitive." The ip model has been the most successful for determining carcinogenicity of inorganic fibers and establishing dose-response relationships; but to determine the possibilities and limitations of this test model, very high doses of nonfibrous silicon carbide and of a slightly durable glass fiber type were injected ip in Wistar rats. No obviously acute or chronic toxic effect was observed in 90 weeks, but there was a 40% incidence of serosal tumors in the group treated with glass fibers. A pilot study on the persistence of slag fibers in the omentum of rats after ip injection showed a half-time of about 1 year. It was calculated that an ip injection of 10(9) fibers would lead to a concentration of fiber numbers in the ash of the omentum in the same range as the concentration in the lung after 2 years of inhalation exposure. The long-term inhalation study with fibers in rats has been called the "gold standard" for risk characterization.(ABSTRACT TRUNCATED AT 250 WORDS

Nutrição mineral de bovinos de corte do Pantanal Mato-Grossense: 2. Micronutrientes na Nhecolandia (Parte Central).

Realatam-se resultados de analise de solos, agua, e gramineas nativas, coletadas em 1979, maio/80 e ago/80, e de figado de bovinos, nessas epocas e em fev/80, na sub-regiao de Nhecolandia, do Pantanal Mato-Grossense. Solos e gramineas foram coletados em cino unidades de paisagem : mata, cerrado, caronal, campo limpo e lagoa. Os resultados sugerem a possibilidade de ocorrencia de toxidez de ferro e manganes, durante /apos o periodo de inundacao, e de deficiencias de cobre e zinco, em determinadas epocas, na sub-regiao abrangida

A Study of Cattle "Temperament" and its Measurement

Author Institution: State Normal School, Stevens Point, Wisconsi