11,215 research outputs found

    On the Canonical Equivalence of Liouville and Free Fields

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    We obtain the parity invariant generating functional for the canonical transformation mapping the Liouville theory into a free scalar field and explain how it is related to the pseudoscalar transformationComment: 8 pages, Latex, Important earlier work by G.P. Jordadze acknowledge

    The symmetries of the Dirac--Pauli equation in two and three dimensions

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    We calculate all symmetries of the Dirac-Pauli equation in two-dimensional and three-dimensional Euclidean space. Further, we use our results for an investigation of the issue of zero mode degeneracy. We construct explicitly a class of multiple zero modes with their gauge potentials.Comment: 22 pages, Latex. Final version as published in JMP. Contains an additional subsection (4.2) with the explicit construction of multiple zero mode

    Developing Country Debt and the Market Value of Large Commercial Banks

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    The effect on commercial banks of exposure to large amounts of developing country debt has been a topic of increasing concern in recent years. Fear of default on the part of the debtor countries has led to fears for the solvency of the creditor banks since in many cases the total of outstanding exposure to risky debtors exceeds the entire capital base of the banks involved. The paper presents a first effort towards measuring the effects of LDC debt exposure on the market value of large commercial value banks in the United States. Our results indicate that exposure to developing country debt has exerted a measurable and significant negative effect on the ratio of market to book value for these banks.

    Reducing the hypoxic fraction of a tumour model by growth in low glucose.

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    The question of whether growth under low glucose conditions leads to a reduced amount of cell hypoxia was investigated using an in vitro tumour analogue, the sandwich system. In this multicellular system, the interplay between diffusion and consumption of oxygen and nutrients results in spatial gradients of these environmental factors. Gradients in the environment lead to biological heterogeneity within the cell population. A necrotic centre, surrounded by a viable cell border, subsequently develops. Cells adjacent to the necrotic centre in sandwiches are hypoxic and are in an environment somewhat analogous to that of cells adjacent to necrotic regions in solid tumours. Using sandwiches of the 9L and V79 cell lines, the effects of growth under low glucose conditions on the degree of hypoxia in regions adjacent to the necrotic centre were investigated. Per-cell binding of 3H-misonidazole, assessed by autoradiography, was used as an indicator of oxygen deprivation. It was found that the extent of the hypoxic region and the severity of hypoxia were considerably reduced by growing sandwiches in a glucose concentration of 0.6 mM rather than 6.5 mM. This reduction was found in conjunction with a smaller viable border; it occurred despite the fact that the average per-cell oxygen consumption is higher in the low glucose sandwiches. The data are qualitatively consistent with a joint oxygen-glucose deprivation model for cell necrosis

    Scaling Up Malaria Control in Africa: An Economic and Epidemiological Assessment

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    This paper estimates the number of people at risk of contracting malaria in Africa using GIS methods and the disease's epidemiologic characteristics. It then estimates yearly costs of covering the population at risk with the package of interventions (differing by level of malaria endemicity and differing for rural and urban populations) for malaria as recommended by the UN Millennium Project. These projected costs are calculated assuming a ramp-up of coverage to full coverage by 2008, and then projected out through 2015 to give a year-by-year cost of meeting the Millennium Development Goal for reducing the burden of malaria by 75% We conclude that the cost of comprehensive malaria control for Africa is US3.0billionperyearonaverage,oraroundUS3.0 billion per year on average, or around US4.02 per African at risk.

    Africa's Lagging Demographic Transition: Evidence from Exogenous Impacts of Malaria Ecology and Agricultural Technology

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    Much of Africa has not yet gone through a "demographic transition" to reduced mortality and fertility rates. The fact that the continent's countries remain mired in a Malthusian crisis of high mortality, high fertility, and rapid population growth (with an accompanying state of chronic extreme poverty) has been attributed to many factors ranging from the status of women, pro-natalist policies, poverty itself, and social institutions. There remains, however, a large degree of uncertainty among demographers as to the relative importance of these factors on a comparative or historical basis. Moreover, econometric estimation is complicated by endogeneity among fertility and other variables of interest. We attempt to improve estimation (particularly of the effect of the child mortality variable) by deploying exogenous variation in the ecology of malaria transmission and in agricultural productivity through the staggered introduction of Green Revolution, high-yield seed varieties. Results show that child mortality (proxied by infant mortality) is by far the most important factor among those explaining aggregate total fertility rates, followed by farm productivity. Female literacy (or schooling) and aggregate income do not seem to matter as much, comparatively.

    Transformations to achieve the Sustainable Development Goals Includes the SDG Index and Dashboards. Sustainable Development Report 2019

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    The Sustainable Development Report 2019 presents an updated SDG Index and Dashboards with a refined assessment of countries’ distance to SDG targets. The report has been successfully audited for the first time by the European Commission Joint Research Centre. New indicators have been included, primarily to refine the indicator selection on agriculture, diets, gender equality and freedom of speech. We have also added more metrics for international spillovers, including on fatal work accidents. A new website and data visualization tools are available (http://sustainabledevelopment.report). Once again, Nordic countries – Denmark, Sweden and Finland – top the SDG Index. Yet, even these countries face major challenges in implementing one or several SDGs. No country is on track for achieving all 17 goals with major performance gaps even in the top countries on SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), SDG 14 (Life Below Water) and SDG 15 (Life on Land). Income and wealth inequalities, as well as gaps in health and education outcomes by population groups also remain important policy challenges in developing and developed countries alike. The Sustainable Development Report 2019 generates seven major findings: 1. High-level political commitment to the SDGs is falling short of historic promises In September 2019, heads-of-states and governments will convene for the first time in person at the UN in New York to review progress on their promises made four years after the adoption of the 2030 Agenda. Yet, our in-depth analyses show that many have not taken the critical steps to implement the SDGs. Out of 43 countries surveyed on SDG implementation efforts, including all G20 countries and countries with a population greater than 100 million, 33 countries have endorsed the SDGs in official statements since January 1st, 2018. Yet in only 18 of them do central budget documents mention the SDGs. This gap between rhetoric and action must be closed. 2. The SDGs can be operationalized through six SDG Transformations SDG implementation can be organized along the following Transformations: 1. Education, Gender, and Inequality; 2. Health, Wellbeing, and Demography; 3. Energy Decarbonization and Sustainable Industry; 4. Sustainable Food, Land, Water, Oceans; 5. Sustainable Cities and Communities; and 6. Digital Revolution for Sustainable Development. The transformations respect strong interdependencies across the SDGs and can be operationalized by well-defined parts of governments in collaboration with civil society, business, and other stakeholders. They must be underpinned and guided by the principles of Leave No One Behind and Circularity and Decoupling of resource use from human wellbeing. 3. Trends on climate (SDG 13) and biodiversity (SDG 14 and SDG 15) are alarming On average, countries obtain their worst scores on SDG 13 (Climate Action), SDG 14 (Life Below Water) and SDG 15 (Life on Land). No country obtains a “green rating” (synonym of SDG achieved) on SDG 14 (Life Below Water). Trends on greenhouse gas emissions and, even more so, on threatened species are moving in the wrong direction. These findings are in line with the recent reports from the IPCC and IPBES on climate change mitigation and biodiversity protection, respectively. 4. Sustainable land-use and healthy diets require integrated agriculture, climate and health policy interventions Land use and food production are not meeting people’s needs. Agriculture destroys forests and biodiversity, squanders water and releases one-quarter of global greenhouse-gas emissions. In total, 78% of world nations for which data are available obtain a “red rating” (synonym of major SDG challenge) on sustainable nitrogen management; the highest number of “red” rating across all indicators included in the report. At the same time, one-third of food is wasted, 800 million people remain undernourished, 2 billion are deficient in micronutrients, and obesity is on the rise. New indicators on nations’ trophic level and yield gap closure highlight the depth of the challenge. Transformations towards sustainable landuse and food systems are required to balance efficient and resilient agriculture and forestry with biodiversity conservation and restoration as well as healthy diets

    A two-point boundary value problem on a Lorentz manifold arising in A. Poltorak's concept of reference frame

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    In A. Poltorak's concept, the reference frame in General Relativity is a certain manifold equipped with a connection. The question under consideration here is whether it is possible to join two events in the space-time by a time-like geodesic if they are joined by a geodesic of the reference frame connection that has a time-like initial vector. This question is interpreted as whether an event belongs to the proper future of another event in the space-time in case it is so in the reference frame. For reference frames of two special types some geometric conditions are found under which the answer is positive.Comment: 11 page
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