7,922 research outputs found

    Crew procedures and workload of retrofit concepts for microwave landing system

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    Crew procedures and workload for Microwave Landing Systems (MLS) that could be retrofitted into existing transport aircraft were evaluated. Two MLS receiver concepts were developed. One is capable of capturing a runway centerline and the other is capable of capturing a segmented approach path. Crew procedures were identified and crew task analyses were performed using each concept. Crew workload comparisons were made between the MLS concepts and an ILS baseline using a task-timeline workload model. Workload indexes were obtained for each scenario. The results showed that workload was comparable to the ILS baseline for the MLS centerline capture concept, but significantly higher for the segmented path capture concept

    The outcome of Mental Health Care Users admitted under Section 40 of the South African Mental Health Care Act (No 17 of 2002)

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    Objective: To determine the outcomes of mental health care users (MHCU’s) admitted in terms of Section 40 of the South African Mental Health Care Act (No 17 of 2002) (MHCA) and the factors, if any, that are associated with these outcomes. Method: The study was a retrospective record review of MHCU’s, 18 years and older, referred by the South African Police Service (SAPS) to Chris Hani Baragwanath Hospital (CHBH). All mental health care users handed over to CHBH by SAPS with completed MHCA form 22’s during the period July 2007 to December 2007 were included in the study. The outcomes, demographics and clinical characteristics of these referrals were obtained from hospital records. Results: During the six-month study period, 718 MHCU’s were referred by members of SAPS to the CHBH Emergency Department. Associations were found between discharged MHCU’s and i) being male, ii) being less than 35 years of age, iii) being unemployed, iv) having a lower level of education, v) having a past history of substance abuse and/or vi) a past psychiatric illness. Females were twice as likely to be unemployed and admitted to hospital (either to a psychiatric or general medical ward). MHCU’s diagnosed with delirium were more likely to be admitted intoa medical ward as compared to a psychiatric ward. Conclusion: As has been the case in most countries where police services have been incorporated into mental health acts, South Africa’s new Mental Health Care Act (No 17 of 2002) has resulted in a large number of referrals by the police to mental health services. However, many of these referrals may not be necessary as most MHCU’s end up not being admitted. The characteristics of police referrals suggest that the receiving facility should have thecapacity to identify factors that favour outpatient care (especially substance abuse problems) and divert MHCU’s presenting with such factors to appropriate treatment facilities without admitting them to the hospital.Keywords: Mental Health Care Act; Outcome; Police services; Mental illness, South Afric

    Effect of non-zero constant vorticity on the nonlinear resonances of capillary water waves

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    The influence of an underlying current on 3-wave interactions of capillary water waves is studied. The fact that in irrotational flow resonant 3-wave interactions are not possible can be invalidated by the presence of an underlying current of constant non-zero vorticity. We show that: 1) wave trains in flows with constant non-zero vorticity are possible only for two-dimensional flows; 2) only positive constant vorticities can trigger the appearance of three-wave resonances; 3) the number of positive constant vorticities which do trigger a resonance is countable; 4) the magnitude of a positive constant vorticity triggering a resonance can not be too small.Comment: 6 pages, submitte

    The beam observation system of the ISOLDE facility

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    Simulations of Dust in Interacting Galaxies I: Dust Attenuation

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    A new Monte-Carlo radiative-transfer code, Sunrise, is used in conjunction with hydrodynamic simulations of major galaxy mergers to calculate the effects of dust in such systems. The simulations are in good agreement with observations of dust absorption in starburst galaxies, and the dust has a profound effect on their appearance. The dust attenuation increases with luminosity such that at peak luminosities ~90% of the bolometric luminosity is absorbed by dust. In general, the detailed appearance of the merging event depends on the stage of the merger and the geometry of the encounter. The fraction of bolometric energy absorbed by the dust, however, is a robust quantity that can be predicted from the intrinsic properties bolometric luminosity, baryonic mass, star-formation rate, and metallicity of the system. This paper presents fitting formulae, valid over a wide range of masses and metallicities, from which the absorbed fraction of luminosity (and consequently also the infrared dust luminosity) can be predicted. The attenuation of the luminosity at specific wavelengths can also be predicted, albeit with a larger scatter due to the variation with viewing angle. These formulae for dust attenuation appear to be valid for both isolated and interacting galaxies, are consistent with earlier studies, and would be suitable for inclusion in theoretical models, e.g. semi-analytic models of galaxy formation.Comment: 12 pages, 10 figures, submitted to Ap

    Uso potencial da brita e argila na redução da toxicidade de efluentes da aquicultura contendo diflubenzuron.

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    Resumo: O crescimento acelerado da aquicultura no Brasil e no mundo vem a atender a uma demanda crescente por proteína animal. No entanto, este crescimento deve vir acompanhado da medidas de conservação dos recursos naturais, bem como a minimização dos impactos sobre a qualidade da água dos viveiros de criação e dos efluentes gerados por esta atividade. O presente estudo tem por objetivo avaliar a toxicidade do inseticida diflubenzuron (usado na piscicultura) sobre o organismo Artemia salina, após a filtragem com um sistema natural de tratamento de efluentes, utilizando como meios filtrantes a brita e a argila expandida. Os resultados obtidos indicam que a argila expandida foi mais eficiente na redução da toxicidade do que a brita. Embora ainda sejam necessários testes com outros organismos não alvo, sugere-se o uso da argila como filtro na saída dos viveiros para melhoria da qualidade da água do efluente

    The use of digital photographs for the diagnosis of hand osteoarthritis: the AGES-Reykjavik study

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    <p>Abstract</p> <p>Background</p> <p>The objective of the study was to standardize a method using digital photographs to diagnose and grade hand osteoarthritis (HOA), to compare it with radiographs and clinical examination with regard to prevalence and relation to symptoms, and finally to construct a simple shortened version suitable for use in very large studies, where a global estimate may be preferable.</p> <p>Methods</p> <p>High quality photographs with standard distance and hand positioning were analysed for the presence of HOA and subsequently compared with standard radiographs and clinical examination in 381 random participants in the AGES-Reykjavik Study, a large population study. The mean age of the participants was 76 years.</p> <p>Results</p> <p>Using the photographic method, the most commonly affected joints were the second DIP joints followed by the third DIP joints and second and third PIP joints. Both interobserver (ICC = 0.83) and intraobserver reading agreements (ICC = 0.89) were acceptable. On comparison with radiography and clinical examination, aggregate scores were significantly correlated (R<sub>s </sub>0.35-0.69), more so in females (R<sub>s </sub>0.53-0.72) than males. Hand pain in males showed very little association with HOA findings by the three methods but all methods showed a comparable moderate association with hand pain in females. The performance of photography in predicting pain on most days for at least a month in females was comparable to that of radiography and clinical examination (AUC 0.63 <it>p </it>= 0.004). Analysis of intermittent pain yielded similar results for in the DIP and PIP joints (OR 3.2-3.3, <it>p </it>< 0.01), but for the CMC1 joints, both radiography (OR 9.0, <it>p </it>< 0.0001), and clinical examination (OR 9.8, <it>p </it>< 0.0001), had higher predictive odds ratios for pain than photography (OR 3.6, <it>p </it>< 0.0001)., A shortened, rapidly performed form of reading photographs also showed a high degree of correlation with the other methods (R<sub>s </sub>0.56-0.82).</p> <p>Conclusion</p> <p>High quality hand photographs can be used to diagnose and grade hand osteoarthritis. The method has the advantage of being inexpensive and easy to perform. By using a slightly simplified method of reading, it appears to be highly suitable for use in large studies.</p

    Phase Transitions Driven by Vortices in 2D Superfluids and Superconductors: From Kosterlitz-Thouless to 1st Order

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    The Landau-Ginzburg-Wilson hamiltonian is studied for different values of the parameter λ\lambda which multiplies the quartic term (it turns out that this is equivalent to consider different values of the coherence length ξ\xi in units of the lattice spacing aa). It is observed that amplitude fluctuations can change dramatically the nature of the phase transition: for small values of λ\lambda (ξ/a>0.7\xi/a > 0.7), instead of the smooth Kosterlitz-Thouless transition there is a {\em first order} transition with a discontinuous jump in the vortex density vv and a larger non-universal drop in the helicity modulus. In particular, for λ\lambda sufficiently small (ξ/a≅1\xi/a \cong 1), the density of bound pairs of vortex-antivortex below TcT_c is so low that, vv drops to zero almost for all temperature T<TcT<Tc.Comment: 8 pages, 5 .eps figure

    Stability and electronic structure of the complex K2_2PtCl6_6 structure-type hydrides

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    The stability and bonding of the ternary complex K2_2PtCl6_6 structure hydrides is discussed using first principles density functional calculations. The cohesion is dominated by ionic contributions, but ligand field effects are important, and are responsible for the 18-electron rule. Similarities to oxides are discussed in terms of the electronic structure. However, phonon calculations for Sr2_2RuH6_6 also show differences, particularly in the polarizability of the RuH6_6 octahedra. Nevertheless, the yet to be made compounds Pb2_2RuH6_6 and Be2_2FeH6_6 are possible ferroelectrics. The electronic structure and magnetic properties of the decomposition product, FeBe2_2 are reported. Implications of the results for H storage are discussed

    Avaliação da toxicidade da sulfametazina em organismos aquáticos.

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    Resumo: Dentre os fármacos, o grupo dos antibióticos, entre eles as sulfonamidas, é considerado um dos mais importantes. Estes compostos são extensivamente utilizados na medicina humana, veterinária e na aquicultura, com o propósito de prevenir ou tratar infecções microbianas. Essas substâncias podem acumular-se no solo, sofrer lixiviação ou, ainda, ser transportada via escoamento superficial para os corpos hídricos. A fim de alcançar um maior entendimento sobre os efeitos das sulfonamidas, avaliou-se a toxicidade aguda da sulfametazina utilizando-se duas espécies de invertebrados aquáticos (Daphnia similis e Artemia salina) e o peixe (Piaractus mesopotamicus). Foram determinados os valores de concentração efetiva media (CE50-48h), relacionada à imobilidade dos microcrustáceos equivalente a 77,5-48h e >1000 mg L-¹ para D. similis e A. salina, respectivamente. Para o peixe P. mesopotamicus, não houve efeito letal. Considerando-se que estes compostos são administrados em doses elevadas, a avaliação do seu impacto em toda biota aquática parece aconselhável. Os valores, portanto auxiliam para o estabelecimento de concentrações máximas permissíveis de sulfametazina nos corpos de água. Abstract: Among the drugs, the group of antibiotics, including sulfonamides, is considered one of the most important. These compounds are extensively used in human, veterinary medicine and aquaculture, with the purpose of preventing or treating microbial infections. These substances can build up in the soil, leachate or even be transported via superficial runoff to water bodies. In order to achieve a better understanding of the effects of sulfonamides, the acute toxicity of sulfamethazine was evolved using two species of aquatic invertebrates (Daphnia similis and artemia salina) and fish (Piaractus mesopotamicus). Determined the average effective concentration values were (EC50-48h), related to immobility of microcrustaceans equivalent to 77.5-48h and>1000 mg L -1 for D. similis and A. salina, respectively. For the fish P. mesopotamicus not lethal effect was found. Considering that these compounds are administered in high doses, to assess their impact on aquatic biota all seems advisable. values thus help to establish allowable maximum concentrations of sulfamethazine in water bodies
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