We constrain the distribution of calcium across the surface of the white dwarf star G29-38 by combining time-series spectroscopy from Gemini-North with global time-series photometry from the Whole ...Earth Telescope. G29-38 is actively accreting metals from a known debris disk. Since the metals sink significantly faster than they mix across the surface, any inhomogeneity in the accretion process will appear as an inhomogeneity of the metals on the surface of the star. We measure the flux amplitudes and the calcium equivalent width amplitudes for two large pulsations excited on G29-38 in 2008. The ratio of these amplitudes best fits a model for polar accretion of calcium and rules out equatorial accretion.
Information on the diameter at the breast height (DBH) growth of trees can be useful to understand their productivity and temporal dynamics in natural forests. This study presents the first results ...of increments in DBH of Araucaria angustifolia trees since their logging prohibition in southern Brazil, in late 1970s. We used dendrochronology techniques in 210 individuals in three different sites, which allowed a retrospective analysis of the DBH increment from 60 to 150 years. We adjusted temporal dimensional models whose results may help to support a sustainable forest management of A. angustifolia in southern Brazil. The results showed that the width of annual growth rings varied from 0.04 to 4.8 cm year-1 along the last 60 to 150 years, and the mean annual increment ranged from 0.3 to 0.9 cm year-1. The DBH increment accumulated in the last ten years showed a decreasing pattern, indicating that most of the sampled trees had already reached maturity. This result denotes a proportional loss in DBH increment with increasing DBH and age. Decreasing DBH growth rates became even more evident in the last ten years (i.e. ~0.15 cm year-1), indicating a need of silvicultural intervention in some sites to reduce competition among trees for soil nutrients and light. Regarding the average DBH increment growth, the time the trees need to reach the optimal DBH harvesting diameter of 40 cm ranged from 25 to 112 years, according to the local site index characteristics. The curve inflection point that represents the DBH increment occurred between 35 and 45 years for this specific DBH. These results confirm the viability and need of forest management practices of A. angustifolia trees due to the saturation of the trees DBH growth and increment capacity that reached its inflection. Therefore, since their logging prohibition, most A. angustifolia trees reached their optimal DBH harvesting size. Forest management is necessary for conservation of the forest structure. It would favor the growth of young A. angustifolia, seedling productions, the natural regeneration of this species and genetic diversity; and stimulate the increase of timber production.
Rocky Mountain spotted fever is an infectious, acute febrile disease of variable severity. It can range from mild and atypical clinical forms to severe forms, with a high lethality rate. Rocky ...Mountain spotted fever is caused by a bacterium of the genus Rickettsia, transmitted by tick bites. In Brazil, two species of rickettsiae are associated with clinical conditions of Spotted Fever. Rickettsia rickettsii, which leads to Brazilian Spotted Fever (BSF), considered a serious disease, registered in the north of the state of Paraná and in the states of the Southeast Region. Rickettsia parkeri, which has been recorded in environments of the Atlantic Forest (Rio Grande do Sul, Santa Catarina, Bahia and Ceará), producing less severe clinical conditions.The objective of this article wasto describe through a literature review, Rocky Mountain spotted fever in Brazil, forms of transmission, treatment, mortality and clinical manifestations.In Brazil, the main vectors are ticks of the genus Amblyomma, such as A. sculptum (= A. cajennense) known as the star tick, A. aureolatum and A. ovale. However, potentially, any species of tick can harbor the bacteria that cause Rocky Mountain Spotted Fever, such as the dog tick.
We constrain the distribution of calcium across the surface of the white dwarf star G29-38 by combining time series spectroscopy from Gemini-North with global time series photometry from the Whole ...Earth Telescope. G29-38 is actively accreting metals from a known debris disk. Since the metals sink significantly faster than they mix across the surface, any inhomogeneity in the accretion process will appear as an inhomogeneity of the metals on the surface of the star. We measure the flux amplitudes and the calcium equivalent width amplitudes for two large pulsations excited on G29-38 in 2008. The ratio of these amplitudes best fits a model for polar accretion of calcium and rules out equatorial accretion.
Beginning in 1940, Mexico enjoyed a 30-year period of sustained economic growth; on the demographic side, this interval was characterized by sustained high fertility and rapidly falling mortality. By ...the early 1980s, the country faced crises of liquidity and inflation; a fertility decline had set in after the early 1970s. This assessment of four decades of economic, social, and demographic change explores reasons why fertility remained high in the face of rapid development; how demographic change contributed to the current economic crisis; and why fertility declined precipitously in the most recent period. The authors argue that development policy helped perpetuate high fertility for several decades; population policy, they believe, exerted an identifiable downward influence on Mexican fertility.
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