Comments on alternative calculations of the broadening of spectral lines of neutral sodium by H-atom collisions

With the exception of the sodium D-lines recent calculations of line broadening cross-sections for several multiplets of sodium by Leininger et al (2000) are in substantial disagreement with cross-sections interpolated from the tables of Anstee and O'Mara (1995) and Barklem and O'Mara (1997). The discrepancy is as large as a factor of three for the 3p-4d multiplet. The two theories are tested by using the results of each to synthesize lines in the solar spectrum. It is found that generally the data from the theory of Anstee, Barklem and O'Mara produce the best match to the observed solar spectrum. It is found, using a simple model for reflection of the optical electron by the potential barrier between the two atoms, that the reflection coefficient is too large for avoided crossings with the upper states of subordinate lines to contribute to line broadening, supporting the neglect of avoided ionic crossings by Anstee, Barklem and O'Mara for these lines. The large discrepancies between the two sets of calculations is a result of an approximate treatment of avoided ionic crossings for these lines by Leininger et al (2000).Comment: 18 pages, 5 ps figures included, to appear in J Phys B: At. Mol. Opt. Phy

Nestedness of Ectoparasite-Vertebrate Host Networks

Determining the structure of ectoparasite-host networks will enable disease ecologists to better understand and predict the spread of vector-borne diseases. If these networks have consistent properties, then studying the structure of well-understood networks could lead to extrapolation of these properties to others, including those that support emerging pathogens. Borrowing a quantitative measure of network structure from studies of mutualistic relationships between plants and their pollinators, we analyzed 29 ectoparasite-vertebrate host networks—including three derived from molecular bloodmeal analysis of mosquito feeding patterns—using measures of nestedness to identify non-random interactions among species. We found significant nestedness in ectoparasite-vertebrate host lists for habitats ranging from tropical rainforests to polar environments. These networks showed non-random patterns of nesting, and did not differ significantly from published estimates of nestedness from mutualistic networks. Mutualistic and antagonistic networks appear to be organized similarly, with generalized ectoparasites interacting with hosts that attract many ectoparasites and more specialized ectoparasites usually interacting with these same “generalized” hosts. This finding has implications for understanding the network dynamics of vector-born pathogens. We suggest that nestedness (rather than random ectoparasite-host associations) can allow rapid transfer of pathogens throughout a network, and expand upon such concepts as the dilution effect, bridge vectors, and host switching in the context of nested ectoparasite-vertebrate host networks

Natural analogue synthesis report, TDR-NBS-GS-000027 rev00 icn 02

The purpose of this report is to present analogue studies and literature reviews designed to provide qualitative and quantitative information to test and provide added confidence in process models abstracted for performance assessment (PA) and model predictions pertinent to PA. This report provides updates to studies presented in the Yucca Mountain Site Description (CRWMS M&O 2000 [151945], Section 13) and new examples gleaned from the literature, along with results of quantitative studies conducted specifically for the Yucca Mountain Site Characterization Project (YMP). The intent of the natural analogue studies was to collect corroborative evidence from analogues to demonstrate additional understanding of processes expected to occur during postclosure at a potential Yucca Mountain repository. The report focuses on key processes by providing observations and analyses of natural and anthropogenic (human-induced) systems to improve understanding and confidence in the operation of these processes under conditions similar to those that could occur in a nuclear waste repository. The process models include those that represent both engineered and natural barrier processes. A second purpose of this report is to document the various applications of natural analogues to geologic repository programs, focusing primarily on the way analogues have been used by the YMP. This report is limited to providing support for PA in a confirmatory manner and to providing corroborative inputs for process modeling activities. Section 1.7 discusses additional limitations of this report. Key topics for this report are analogues to emplacement drift degradation, waste form degradation, waste package degradation, degradation of other materials proposed for the engineered barrier, seepage into drifts, radionuclide flow and transport in the unsaturated zone (UZ), analogues to coupled thermal-hydrologic-mechanical-chemical processes, saturated zone (SZ) transport, impact of radionuclide release on the biosphere, and potentially disruptive events. Results of these studies will be used to corroborate estimates of the magnitude and limitation of operative processes in order to build realism into conceptual and numerical process models used as a foundation for PA in the representative case of postclosure safety

Características ergonômicas dos tratores agrícolas utilizados na região central do Rio Grande do Sul Ergonomic characteristics of agricultural tractors used in central region of Rio Grande do Sul State, Brazil

A utilização de tratores agrícolas com boas condições ergonômicas reduz a probabilidade de ocorrência de acidentes e doenças ocupacionais, aumentando a eficiência dos trabalhadores. Neste trabalho, objetivou-se verificar a presença de itens relacionados à ergonomia de tratores agrícolas usados, bem como avaliar o comportamento destas características em função do tempo de uso das referidas máquinas. Foram analisados 175 tratores agrícolas pertencentes às microrregiões gaúchas de Santa Maria, Restinga Seca e Cachoeira do Sul, presentes em 114 propriedades aleatoriamente amostradas. Os resultados mostraram que apenas 3% dos espécimes avaliados eram equipados com cabina, sendo que a maior parte dos mesmos não apresentava isolamento do calor gerado pelo motor e transmissão. Com relação à ergonomia dos comandos, mais de 70% dos tratores tinham alavancas de câmbio centrais, enquanto que apenas 8% eram equipados com volante de direção regulável. Da mesma forma, mais de 20% dos exemplares amostrados possuíam bancos sem estofamento. Além disso, a presença dos itens avaliados foi menor para os tratores mais antigos.<br>It is possible to reduce the probability of work accidents, diseases occurrence and increase the work efficiency using agricultural tractors with good ergonomic conditions. The objective of this research was to verify the presence of ergonomic items in used agricultural tractors and also to evaluate the influence of tractor age in these characteristics. 175 agricultural tractors belonging to 3 regions of Rio Grande do Sul State (Santa Maria, Restinga Seca and Cachoeira do Sul, Brazil), present in 114 farms randomly sampled, were evaluated. The results showed that only 3% of sampled specimens were equipped with a cab, and most part of the tractors did not have protection against the heat produced by tractor transmission and engine. With regard to ergonomics of commands, more than 70% of the tractors had gear levers positioned in its longitudinal central line, and only 8% were equipped with adjustable steering wheel. In the same way, more than 20% of sampled specimens did not have upholstered seat. Besides, the presence of the evaluated items were smaller for older tractors

Eventos de vida estressantes entre idosos brasileiros residentes na comunidade Stressful life events in Brazilian community-dwelling elderly

Foram investigados eventos de vida estressantes em 544 idosos participantes do estudo PENSA, em Minas Gerais (74,6% de mulheres e 25,4% de homens; média de idade = 72,11; DP ± 8,29; sendo 42,1% de 60 a 69 anos; 39%, de 70 a 79 e 18,9%, 80 a 99). Os eventos compuseram as seguintes categorias: eventos relacionados à finitude (morte ou doença), problemas que afetam os descendentes, relacionados ao cuidado, eventos pontuais e bem-estar psicológico. Os homens relataram eventos pontuais (60-69), problemas dos descendentes (70-79), e finitude e bem-estar (> 80); as mulheres relataram eventos pontuais (60-69), problemas dos descendentes (60-79) e finitude (> 80). As mulheres consideraram os eventos como mais estressantes do que os homens. Resultados semelhantes têm sido relatados na literatura.<br>We examined stressful life events in 544 elderly participants of PENSA, in Minas Gerais (74.6% women and 25.4% men; age = 72.11; ± 8.29; 42.1% aged 60-69; 39% 70-79 and 18.9%, 80-99). Stressful life events were classified into categories related to: death and illness, problems affecting children, caregiving, turning points (transitions), and psychological well-being. Men reported turning points (60-69), problems affecting their children (70-79), death and illness and psychological well-being (> 80); women reported turning points (transitions) (60-69), problems affecting their children (60-79), and own death and illness (> 80). Women evaluated events as more stressful than men did. There are similar results in the literature