27 research outputs found

    The AuScope geodetic VLBI array

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    The AuScope geodetic Very Long Baseline Interferometry array consists of three new 12-m radio telescopes and a correlation facility in Australia. The telescopes at Hobart (Tasmania), Katherine (Northern Territory) and Yarragadee (Western Australia) are co-located with other space geodetic techniques including Global Navigation Satellite Systems (GNSS) and gravity infrastructure, and in the case of Yarragadee, satellite laser ranging (SLR) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) facilities. The correlation facility is based in Perth (Western Australia). This new facility will make significant contributions to improving the densification of the International Celestial Reference Frame in the Southern Hemisphere, and subsequently enhance the International Terrestrial Reference Frame through the ability to detect and mitigate systematic error. This, combined with the simultaneous densification of the GNSS network across Australia, will enable the improved measurement of intraplate deformation across the Australian tectonic plate. In this paper, we present a description of this new infrastructure and present some initial results, including telescope performance measurements and positions of the telescopes in the International Terrestrial Reference Frame. We show that this array is already capable of achieving centimetre precision over typical long-baselines and that network and reference source systematic effects must be further improved to reach the ambitious goals of VLBI2010

    Spinster Homolog 2 (Spns2) Deficiency Causes Early Onset Progressive Hearing Loss

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    Spinster homolog 2 (Spns2) acts as a Sphingosine-1-phosphate (S1P) transporter in zebrafish and mice, regulating heart development and lymphocyte trafficking respectively. S1P is a biologically active lysophospholipid with multiple roles in signalling. The mechanism of action of Spns2 is still elusive in mammals. Here, we report that Spns2-deficient mice rapidly lost auditory sensitivity and endocochlear potential (EP) from 2 to 3 weeks old. We found progressive degeneration of sensory hair cells in the organ of Corti, but the earliest defect was a decline in the EP, suggesting that dysfunction of the lateral wall was the primary lesion. In the lateral wall of adult mutants, we observed structural changes of marginal cell boundaries and of strial capillaries, and reduced expression of several key proteins involved in the generation of the EP (Kcnj10, Kcnq1, Gjb2 and Gjb6), but these changes were likely to be secondary. Permeability of the boundaries of the stria vascularis and of the strial capillaries appeared normal. We also found focal retinal degeneration and anomalies of retinal capillaries together with anterior eye defects in Spns2 mutant mice. Targeted inactivation of Spns2 in red blood cells, platelets, or lymphatic or vascular endothelial cells did not affect hearing, but targeted ablation of Spns2 in the cochlea using a Sox10-Cre allele produced a similar auditory phenotype to the original mutation, suggesting that local Spns2 expression is critical for hearing in mammals. These findings indicate that Spns2 is required for normal maintenance of the EP and hence for normal auditory function, and support a role for S1P signalling in hearing

    Use of spreadsheets in environment education: an application for solid waste management

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    Spreadsheets have gained increasing popularity in engineering applications, used by both students and practicing engineers. In addition to their low cost, they are easy to learn, and provide the user with the flexibility to display different sets of results just upon changing the input data. This paper illustrates the use of an Excel spreadsheet for solid waste management practices. The program, which has been developed as part of the 'Solid Waste Management' course at the Faculty of Engineering and Architecture, American University of Beirut, allows the user to determine the chemical composition of the waste and its corresponding gas generation potential which are directly linked to a module that allows the prediction of the temporal distribution of gas and leachate production from landfills. The data representing the waste composition and chemistry, gas and leachate production are then automatically plotted into a series of curves and bar charts that allow the decision maker and designer to point out important characteristics, trends and relationships among various parameters controlling solid waste management control systems and landfill operations

    Epidemiology of Extra-Pulmonary Tuberculosis in the United States: High Rates Persist in the Post-HIV Era

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    BACKGROUND: The incidence of tuberculosis (TB) in the United States has declined following a logarithmic pattern, with few exceptions. One exception was during the acquired immunodeficiency syndrome (AIDS) epidemic, which was thought to have caused the deviation. However, since then, alternative explanations have been proposed, including the increased burden of chronic diseases, immigration, and the increase in the use of immune suppressant medications.CONCLUSIONS: The HIV/AIDS epidemic likely played a significant role in the 1979-1985 deviation, but not subsequently. Furthermore, EPTB as a proportion of total TB cases has remained high. Further studies to delineate the etiologies of these findings are needed.METHODS : Epidemiological data of the Center for Disease Control and Prevention (CDC) and the Bureau of the Census were analyzed regarding TB incidence, human immunodeficiency virus (HIV) infection, immigration status, and age for the period 1953-2011.RESULTS : Data analysis identified a deviation from the logarithmic decline in TB cases that started in the mid- 2000s. This divergence did not appear to be related to HIV status. The overall decline in TB cases since 1953 has been almost exclusively due to a reduction in pulmonary TB (PTB) and not to extra-pulmonary TB (EPTB)

    Why do African Americans get more colon cancer than Native Africans?

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    The incidence of colorectal cancer (CRC) is dramatically higher in African Americans (AAs) than in Native Africans (NAs) (60:100,000 vs. \u3c1:100,000) and slightly higher than in Caucasian Americans (CAs). To explore whether the difference could be explained by interactions between diet and colonic bacterial flora, we compared randomly selected samples of healthy 50- to 65-y-old AAs (n = 17) with NAs (n = 18) and CAs (n = 17). Diet was measured by 3-d recall, and colonic metabolism by breath hydrogen and methane responses to oral lactulose. Fecal samples were cultured for 7-α dehydroxylating bacteria and Lactobacillus plantarum. Colonoscopic mucosal biopsies were taken to measure proliferation rates. In comparison with NAs, AAs consumed more (P \u3c 0.01) protein (94 ± 9.3 vs. 58 ± 4.1 g/d) and fat (114 ± 11.2 vs. 38 ± 3.0 g/d), meat, saturated fat, and cholesterol. However, they also consumed more (P \u3c 0.05) calcium, vitamin A, and vitamin C, and fiber intake was the same. Breath hydrogen was higher (P \u3c 0.0001) and methane lower in AAs, and fecal colony counts of 7-α dehydroxylating bacteria were higher and of Lactobacilli were lower. Colonic crypt cell proliferation rates were dramatically higher in AAs (21.8 ± 1.1% vs. 3.2 ± 0.8% labeling, P \u3c 0.0001). In conclusion, the higher CRC risk and mucosal proliferation rates in AAs than in NAs were associated with higher dietary intakes of animal products and higher colonic populations of potentially toxic hydrogen and secondary bile-salt-producing bacteria. This supports our hypothesis that CRC risk is determined by interactions between the external (dietary) and internal (bacterial) environments. © 2007 American Society for Nutrition
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