3,074 research outputs found

    Anuga Software for Numerical Simulations of Shallow Water Flows

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    Shallow water flows are governed by the shallow water wave equations, also known as the Saint-Venant system. This paper presents a finite volume method used to solve the two-dimensional shallow water wave equations and how the finite volume method is implemented in ANUGA software. This finite volume method is the numerical method underlying the software. ANUGA is open source software developed by Australian National University (ANU) and Geoscience Australia (GA). This software uses the finite volume method with triangular domain discretisation for the computation. Four test cases are considered in order to evaluate the performance of the software. Overall, ANUGA is a robust software to simulate two-dimensional shallow water flows. Arus air dangkal diatur dalam persamaan gelombang air dangkal, dikenal sebagai sistem Saint-Venant. Penelitian ini menyajikan metode finite volumeyang digunakan untuk menyelesaikan persamaan gelombang air dangkal dua dimensi dan bagaimana metode finite volumediimplementasikan dalam perangkat lunak ANUGA. Metode finite volumeadalah metode numerik yang mendasari perangkat lunakANUGA. ANUGA sendiri adalah perangkat lunak open source yang dikembangkan oleh Australian National University(ANU) dan Geoscience Australia (GA). Perangkat lunak ini menggunakan metode finite volumedengan diskritisasi domain segitiga dalam proseskomputasi. Empat uji kasus digunakan untuk mengevaluasi kinerja perangkat lunak. Secara keseluruhan, ANUGA adalah perangkat lunak yang robust untuk mensimulasikan dua dimensi aliran arus air dangkal

    Flight Respiration and Energetics

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    We Use a Comparative Approach to Examine Some of the Physiological Traits that Make Flight Possible. Comparisons of Related Fliers and Runners Suggest that Fliers Generally Have Higher Aerobic Metabolic Capacities Than Runners But that the Difference is Highly Dependent on the Taxa Studied. the High Metabolic Rates of Fliers Relative to Runners, Especially in Insects, Are Correlated with High Locomotory Muscle Cycle Frequencies and Low Efficiencies of Conversion of Metabolic Power to Mechanical Power. We Examine Some Factors that Produce Variation in Flight Respiration and Energetics. Air Temperature Strongly Affects the Flight Metabolic Rote of Some Insects and Birds. Flight Speed Interacts with Flier Mass, So that Small Fliers Tend to Exhibit a J-Shaped Power Curve and Larger Fliers a U-Shaped Power Curve. as Body Size Increases, Mass-Specific Aerobic Flight Metabolism Decreases in Most Studies, But Mass-Specific Power Output is Constant or Increases, Leading to an Increase in Efficiency with Size. Intraspecific Studies Have Revealed Specific Genetically based Effects on Flight Metabolism and Power Output and Multiple Ecological Correlates of Flight Capabilities

    Changing Fitness Consequences of Hsp70 Copy Number in Transgenic Drosophila Larvae Undergoing Natural Thermal Stress

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    1. Transgenic Manipulation of the Gene Copy Number of Hsp70, Which Encodes the Major Inducible Heat-Shock Protein of Drosophila Melanogaster (Hsp70), Affects Both Hsp70 Levels and Inducible Thermotolerance in the Laboratory; Here Parallel Effects in Transgenic Drosophila Larvae Undergoing Natural or Simulated Natural Thermal Stress Are Demonstrated. 2. Necrotic Fruit Was Infested with Larvae of Either of Two Transgenic Strains, One Transformed with 12 Extra Copies of the Hsp70 Gene (Extra-Copy Strain) and a Sister Strain Possessing Only the Wild-Type Number (10) of Hsp70 Genes (Excision Strain), and Then Allowed to Heat to Variable Extents. 3. as the Intensity of Thermal Stress Increased, the Consequences of Extra Hsp70 Copies Reversed. after No or Moderate Thermal Stress, Excision Larvae Survived Better Than Did Extra Copy Larvae. by Contrast, Extra Copy Larvae Tolerated Intense Hyperthermia Better Than Did Excision Larvae. 4. These Results Establish that the Hsp70-Mediated Enhancement of Stress Tolerance, Previously Demonstrated Only for Artificial Stress Regimes in the Laboratory, Extends to Natural Stress Regimes. 5. Mortality Due to overexpression of Hsp70, However, Also Increases under Mild Natural Stress Regimes, Buttressing the Ecological Relevance of a Hypothesized Evolutionary Trade-Off of the Benefits and Adverse Consequences of Hsp70 Expression

    Caretaker Government and the Evolution of Caretaker Conventions in New Zealand

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    Since the financial crisis immediately following the 1984 general election, various efforts have been made to clarify the role and responsibilities of caretaker governments in New Zealand. The need to do so was given added urgency as a result of the referendum in 1993 in favour of proportional representation. This article examines the recent evolution of New Zealand's caretaker conventions and assesses their application following the first MMP election in late 1996. The article begins with a brief description of caretaker conventions in other parliamentary democracies. It then considers the operation of the caretaker conventions in New Zealand under the previous first-past-the-post electoral system, and discusses the measures taken in the early-to-mid 1990s to clarify these conventions in preparation for MMP. Having evaluated the conduct of government during the lengthy interregnum in late 1996, the article concludes with an analysis of some of the continuing policy issues generated by caretaker governments and outlines possible ways of reducing the frequency and duration of caretaker periods

    Spacecraft leak location using structure-borne noise

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    Guided ultrasonic waves, generated by air escaping through a small hole, have been measured with an 8×8 piezoelectric phased‐array detector. Rapid location of air leaks in a spacecraft skin, caused by high‐speed collisions with small objects, is essential for astronaut survival. Cross correlation of all 64 elements, one pair at a time, on a diced PZT disc combined with synthetic aperture analysis determines the dominant direction of wave propagation. The leak location is triangulated by combining data from two or more detector. To optimize the frequency band selection for the most robust direction finding, noise‐field measurements of a plate with integral stiffeners have been performed using laser Doppler velocimetry. We compare optical and acoustic measurements to analyze the influence of the PZT array detector and its mechanical coupling to the plate

    Severe hyperkalaemia: demographics and outcome

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    Background. Few studies have evaluated the prevalence of severe hyperkalaemia in unselected patient populations.We identified all episodes of severe hyperkalaemia occurring in 1 year, and described patient demographics, clinical response and outcome. We also assessed junior doctor knowledge of its causes and significance. Materials and methods. A retrospective interrogation of the database of the regional biochemical laboratory identified all episodes of severe hyperkalaemia (K ≥ 6.5 mmol/L) occurring in 2011. The understanding of trainee doctors of the importance, causes and treatment of severe hyperkalaemia was assessed by structured questionnaire. Results. Severe hyperkalaemia was recorded in 433 samples (365 patients) giving a prevalence of 0.11%. Thirty-six per cent of episodes occurred in patients under the care of a nephrologist, who were significantly younger than those not under the care of a nephrologist. In the nephrology cohort, 86% occurred in patients with chronic kidney disease (CKD), the majority of which had CKD Stage 5. In the non-nephrology cohort, only 65% occurred in the context of CKD, which was equally distributed between Stages 3 and 5 CKD. In both patient groups, roughly 50% of episodes occurred in association with acute kidney injury (AKI). Acute mortality (death within 48 h of documented severe hyperkalaemia) was higher in the non-nephrology compared with the nephrology cohort. Time to repeat serum potassium was influenced by the clinical setting with shorter time to repeat for acute care compared with ward settings. Assessment of trainee doctor’s knowledge suggested significant deficiencies in relation to severe hyperkalaemia. Conclusions. The prevalence of severe hyperkalaemia was low and occurred predominantly in the context of CKD and/or AKI. The majority of episodes occurred in patients not under the care of a nephrologist. Variability in time to repeat serum potassium levels suggested deficiencies in care, and assessment of trainee doctor’s knowledge suggests the need for further educational initiatives to highlight its importance

    Genome-scale metabolic analysis of Clostridium thermocellum for bioethanol production

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    <p>Abstract</p> <p>Background</p> <p>Microorganisms possess diverse metabolic capabilities that can potentially be leveraged for efficient production of biofuels. <it>Clostridium thermocellum </it>(ATCC 27405) is a thermophilic anaerobe that is both cellulolytic and ethanologenic, meaning that it can directly use the plant sugar, cellulose, and biochemically convert it to ethanol. A major challenge in using microorganisms for chemical production is the need to modify the organism to increase production efficiency. The process of properly engineering an organism is typically arduous.</p> <p>Results</p> <p>Here we present a genome-scale model of <it>C. thermocellum </it>metabolism, <it>i</it>SR432, for the purpose of establishing a computational tool to study the metabolic network of <it>C. thermocellum </it>and facilitate efforts to engineer <it>C. thermocellum </it>for biofuel production. The model consists of 577 reactions involving 525 intracellular metabolites, 432 genes, and a proteomic-based representation of a cellulosome. The process of constructing this metabolic model led to suggested annotation refinements for 27 genes and identification of areas of metabolism requiring further study. The accuracy of the <it>i</it>SR432 model was tested using experimental growth and by-product secretion data for growth on cellobiose and fructose. Analysis using this model captures the relationship between the reduction-oxidation state of the cell and ethanol secretion and allowed for prediction of gene deletions and environmental conditions that would increase ethanol production.</p> <p>Conclusions</p> <p>By incorporating genomic sequence data, network topology, and experimental measurements of enzyme activities and metabolite fluxes, we have generated a model that is reasonably accurate at predicting the cellular phenotype of <it>C. thermocellum </it>and establish a strong foundation for rational strain design. In addition, we are able to draw some important conclusions regarding the underlying metabolic mechanisms for observed behaviors of <it>C. thermocellum </it>and highlight remaining gaps in the existing genome annotations.</p