New Constraints on the Composition of Jupiter from Galileo Measurements and Interior Models

Using the helium abundance measured by Galileo in the atmosphere of Jupiter and interior models reproducing the observed external gravitational field, we derive new constraints on the composition and structure of the planet. We conclude that, except for helium which must be more abundant in the metallic interior than in the molecular envelope, Jupiter could be homogeneous (no core) or could have a central dense core up to 12 Earth masses. The mass fraction of heavy elements is less than 7.5 times the solar value in the metallic envelope and between 1 and 7.2 times solar in the molecular envelope. The total amount of elements other than hydrogen and helium in the planet is between 11 and 45 Earth masses.Comment: 15 pages, 2 figures (1 color

High Pressure Insulator-Metal Transition in Molecular Fluid Oxygen

We report the first experimental evidence for a metallic phase in fluid molecular oxygen. Our electrical conductivity measurements of fluid oxygen under dynamic quasi-isentropic compression show that a non-metal/metal transition occurs at 3.4 fold compression, 4500 K and 1.2 Mbar. We discuss the main features of the electrical conductivity dependence on density and temperature and give an interpretation of the nature of the electrical transport mechanisms in fluid oxygen at these extreme conditions.Comment: RevTeX, 4 figure

Management of chronic obstructive pulmonary disease-A position statement of the South African Thoracic Society: 2019 update.

Objective To revise the South African guideline for the management of COPD based on emerging research that has informed updated recommendations. Key points Smoking is the major cause of COPD, HIV infection, exposure to biomass fuels and tuberculosis are important additional factors. Spirometry is important for the diagnosis of COPD. COPD is either undiagnosed or diagnosed too late, thus limiting the benefit of therapeutic interventions; performing spirometry in at-risk individuals will help to identify COPD early. COPD should be managed as a multisystem disease with attention to comorbidities, particularly cardiovascular disease. Primary and secondary prevention are the most cost-effective strategies in managing COPD. Smoking cessation as well as avoidance of other risk factors can prevent the development of COPD and retard disease progression. Bronchodilators [long-acting muscarinic antagonist (LAMA) or long-acting beta-2 agonists (LABA)] are the mainstay of pharmacotherapy, relieving dyspnoea, reducing acute exacerbations, reducing rate of disease progression and improving quality of life. Inhaled corticosteroids (ICS) are recommended in patients with frequent exacerbations and those with peripheral blood eosinophilia and have a synergistic effect with bronchodilators in improving lung function, quality of life and reducing exacerbation frequency. Oral corticosteroids are not recommended for maintenance treatment of COPD. A therapeutic trial of oral corticosteroids to distinguish corticosteroid responders from non-responders is not recommended. Acute exacerbations of COPD contribute significantly to health care costs, accelerates loss of lung function and increases mortality. A short course of oral corticosteroids (5 days) has been shown to be beneficial in acute exacerbations. Antibiotics are indicated during acute exacerbations associated with purulent sputum. Lifestyle modification, pulmonary rehabilitation (PR), pneumococcal vaccination and annual influenza vaccination are recommended for COPD patients

The Evolution of Enterprise Reform in Africa: From State-Owned Enterprises to Private Participation in Infrastructure - and Back?

Many African state-owned enterprises (SOEs), particularly those in infrastructure, have a long history of poor performance. From the outset, SOE financial and economic performance generally failed to meet the expectations of their creators and funders. By the late 1970s, the situation was alarming, and by early 1980s, critical. The poor financial performance of SOEs became so burdensome to government budgets that it attracted the attention of the international financial institutions, or IFIs. In response, in the 1980s, the World Bank approved SOE reforms that could be summed up in the term commercialization. By the mid-1990s, however, the idea of making SOEs function efficiently and effectively under government management was largely abandoned by the IFIs and privatization and private participation in infrastructure, or PPI became the order of the day. Once more, however, the results were disappointing. PPI has not been as widely adopted as anticipated, nor has it generated the massive resources and changes hoped for, nor has it been widely accepted as beneficial by the African public. The findings of recent studies in Africa suggest that PPI should not be jettisoned, and that the more productive path is to recognize the limitations of the approach, and to work harder at creating the conditions needed to make it function effectively. This will entail, as many have recognized, an end to the view that public and private infrastructure provision is a dichotomy a case of either-or, one or the other and a better appreciation of the extent to which the performance of each is dependent on the competence of the other. In other words, for the private sector to perform well, public sector capacity must be enhanced. Moreover, proposed tactics of reform should fit more closely with the expectations and sentiments of the affected government, consumer base, and general population. This broader approach implies, probably, a reduction in the scope and, certainly, a reduction in the planned speed of operations. Improving infrastructure performance is a long-term matter

Simulating the Impact on the Local Economy of Alternative Management Scenarios for Natural Areas

This working paper estimates the impact on the local economy of the High Garda Natural Park of alternative management scenarios for the West Garda Regional Forest. The local economy is specialized in tourist services and strongly linked to the tourist presence and their level of expenditure. We wish to investigate the effects of the participative management strategy, which takes into account users preferences and the non-participative strategy, using the SAM multiplier analysis. The local SAM has been constructed considering three sectors: agriculture, tourism and a third aggregate sector including all the other activities. The resident population has been divided into two categories: residents employed in the tourist sector and the remaining resident population. The SAM analysis shows that the accounting representation of the local economy is meaningful and that the participative program, if chosen by the central regional management, would be the most desirable program also at the local level

Detecting Starting Point Bias in Dichotomous-Choice Contingent Valuation Surveys

We examine starting point bias in CV surveys with dichotomous choice payment questions and follow-ups, and double-bounded models of the WTP responses. We wish to investigate (1) the seriousness of the biases for the location and scale parameters of WTP in the presence of starting point bias; (2) whether or not these biases depend on the distribution of WTP and on the bids used; and (3) how well a commonly used diagnostic for starting point bias - a test of the null that bid set dummies entered in the right-hand side of the WTP model are jointly equal to zero - performs under various circumstances. Because starting point bias cannot be separately identified in any reliable manner from biases caused by model specification, we use simulation approaches to address this issue. Our Monte Carlo simulations suggest that the effect of ignoring starting point bias is complex and depends on the true distribution of WTP. Bid set dummies tend to soak up misspecifications in the distribution assumed by the researcher for the latent WTP, rather than capturing the presence of starting point bias. Their power in detecting starting point bias is low

A MERGE Model with Endogenous Technological Change and the Cost of Carbon Stabilization

Two stylized backstop systems with endogenous technological learning formulations (ETL) are introduced in MERGE: one for the electric and the other for the non-electric markets. Then the model is applied to analyze the impacts of ETL on carbon-mitigation policy, contrasting the resulting impacts with the situation without learning. As the model considers endogenous technological change in the energy sector only some exogenous key parameters defining the production function are varied together with the assumed learning rates to check the robustness of our results. Based on model estimations and the sensitivity analyses we conclude that increased commitments for the development of new technologies to advance along their learning curves has a potential for substantial reductions in the cost of climate mitigation helping to reach safe concentrations of carbon in the atmosphere