249 research outputs found

    A partition functional and thermodynamic properties of the infinite-dimensional Hubbard model

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    An approximate partition functional is derived for the infinite-dimensional Hubbard model. This functional naturally includes the exact solution of the Falicov-Kimball model as a special case, and is exact in the uncorrelated and atomic limits. It explicitly keeps spin-symmetry. For the case of the Lorentzian density of states, we find that the Luttinger theorem is satisfied at zero temperature. The susceptibility crosses over smoothly from that expected for an uncorrelated state with antiferromagnetic fluctuations at high temperature to a correlated state at low temperature via a Kondo-type anomaly at a characteristic temperature T⋆T^\star. We attribute this anomaly to the appearance of the Hubbard pseudo-gap. The specific heat also shows a peak near T⋆T^\star. The resistivity goes to zero at zero temperature, in contrast to other approximations, rises sharply around T⋆T^\star and has a rough linear temperature dependence above T⋆T^\star.Comment: 18 pages, 6 figures upon request, latex, (to appear in Phys. Rev. B

    The globalisation strategies of five Asian tobacco companies : a comparative analysis and implications for global health governance

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    The global tobacco industry, from the 1960s to mid 1990s, saw consolidation and eventual domination by a small number of transnational tobacco companies (TTC). This paper draws together comparative analysis of five case studies in the special issue on \u27The Emergence of Asian Tobacco Companies: Implications for Global Health Governance.\u27 The cases suggest that tobacco industry globalisation is undergoing a new phase, beginning in the late 1990s, with the adoption of global business strategies by five Asian companies. The strategies were prompted foremost by external factors, notably market liberalisation, competition from TTCs and declining domestic markets. State protection and promotion enabled the industries in Japan, South Korea and China to rationalise their operations ahead of foreign market expansion. The TTM and TTL will likely remain domestic or perhaps regional companies, JTI and KT&G have achieved TTC status, and the CNTC is poised to dwarf all existing companies. This global expansion of Asian tobacco companies will increase competition which, in turn, will intensify marketing, exert downward price pressures along the global value chain, and encourage product innovation. Global tobacco control requires fuller understanding of these emerging changes and the regulatory challenges posed by ongoing globalisation

    High platelet reactivity in patients with acute coronary syndromes undergoing percutaneous coronary intervention: Randomised controlled trial comparing prasugrel and clopidogrel

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    Background: Prasugrel is more effective than clopidogrel in reducing platelet aggregation in acute coronary syndromes. Data available on prasugrel reloading in clopidogrel treated patients with high residual platelet reactivity (HRPR) i.e. poor responders, is limited. Objectives: To determine the effects of prasugrel loading on platelet function in patients on clopidogrel and high platelet reactivity undergoing percutaneous coronary intervention for acute coronary syndrome (ACS). Patients: Patients with ACS on clopidogrel who were scheduled for PCI found to have a platelet reactivity ≄40 AUC with the Multiplate Analyzer, i.e. “poor responders” were randomised to prasugrel (60 mg loading and 10 mg maintenance dose) or clopidogrel (600 mg reloading and 150 mg maintenance dose). The primary outcome measure was proportion of patients with platelet reactivity <40 AUC 4 hours after loading with study medication, and also at one hour (secondary outcome). 44 patients were enrolled and the study was terminated early as clopidogrel use decreased sharply due to introduction of newer P2Y12 inhibitors. Results: At 4 hours after study medication 100% of patients treated with prasugrel compared to 91% of those treated with clopidogrel had platelet reactivity <40 AUC (p = 0.49), while at 1 hour the proportions were 95% and 64% respectively (p = 0.02). Mean platelet reactivity at 4 and 1 hours after study medication in prasugrel and clopidogrel groups respectively were 12 versus 22 (p = 0.005) and 19 versus 34 (p = 0.01) respectively. Conclusions: Routine platelet function testing identifies patients with high residual platelet reactivity (“poor responders”) on clopidogrel. A strategy of prasugrel rather than clopidogrel reloading results in earlier and more sustained suppression of platelet reactivity. Future trials need to identify if this translates into clinical benefit

    Global public policy: Does the new venue for transnational tobacco control challenge the old way of doing things?

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    The World Health Organization has fostered a new global public policy-the Framework Convention for Tobacco Control (FCTC). Until the 1980s, tobacco control was the sole preserve of states. Now, most countries accept the transnational nature of policy. We explain this shift by identifying mutually reinforcing changes in key policy process elements: transnational actors became a source of policy learning; an international venue &lsquo;institutionalized' new policies; networks began to include tobacco control groups and exclude tobacco companies; socioeconomic shifts undermined public support, and the economic case, for tobacco; and the dissemination of scientific evidence helped actors reframe the image of tobacco, from an economic good to a health crisis. These elements combined to produce an environment conducive to &lsquo;comprehensive' tobacco control. Yet the implementation of the FCTC has been slow and uneven, reflecting the continued importance of domestic policy environments, most of which are not conducive to major policy change

    Toenails as biomarker of exposure to essential trace metals: A review

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    Health problems associated with essential trace metals can result from both inadequate (i.e., low intake) and excessive exposures (i.e., from environmental and/or occupational source). Thus, measuring the exposure level is a real challenge for epidemiologists. Among non-invasive biomarkers that intend to measure long-term exposure to essential trace metals, the toenail is probably the biological matrix with the greatest potential. This systematic review collects the current evidence regarding the validity of toenail clippings as exposure biomarker for trace metals such as boron, cobalt, copper, iron, manganese, molybdenum, selenium, silicon, vanadium and zinc. Special attention was paid to the time-window of exposure reflected by the toenail, the intraindividual variability in exposure levels over time in this matrix, and the relationship of toenail with other biomarkers, personal characteristics and environmental sources. Our search identified 139 papers, with selenium and zinc being the most studied elements. The variability among studies suggests that toenail levels may reflect different degrees of exposure and probably correspond to exposures occurred 3–12 months before sampling (i.e., for manganese/selenium). Few studies assessed the reproducibility of results over time and, for samples obtained 1–6 years apart, the correlation coefficient were between 0.26 and 0.66. Trace metal levels in toenails did not correlate well with those in the blood and urine and showed low-moderate correlation with those in the hair and fingernails.This work was supported by FIS grants PI12/00150, PI17CIII/00034 & PI18/00287 (Instituto de Salud Carlos III, State Secretary of R + D + I and European Union (ERDF/ESF, "Investing in your future"))

    Opiates, cocaine and alcohol combinations in accidental drug overdose deaths in New York City, 1990-98

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    Aims Accidental drug overdose contributes substantially to mortality among drug users. Multi-drug use has been documented as a key risk factor in overdose and overdose mortality in several studies. This study investigated the contribution of multiple drug combinations to overdose mortality trends. Design We collected data on all overdose deaths in New York City between 1990 and 1998 using records from the Office of the Chief Medical Examiner (OCME). We standardized yearly overdose death rates by age, sex and race to the 1990 census population for NYC to enable comparability between years relevant to this analysis. Findings Opiates, cocaine and alcohol were the three drugs most commonly attributed as the cause of accidental overdose death by the OCME, accounting for 97.6% of all deaths; 57.8% of those deaths were attributed to two or more of these three drugs in combination. Accidental overdose deaths increased in 1990–93 and subsequently declined slightly in 1993–98. Changes in the rate of multi-drug combination deaths accounted for most of the change in overdose death rates, whereas single drug overdose death rates remained relatively stable. Trends in accidental overdose death rates within gender and racial/ethnic strata varied by drug combination suggesting different patterns of multi-drug use among different subpopulations. Conclusions These data suggest that interventions to prevent accidental overdose mortality should address the use of drugs such as heroin, cocaine and alcohol in combination.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/40256/2/Coffin_Opiates, Cocaine and Alcohol Combinations_2003.pd

    MEDEAS: a new modeling framework integrating global biophysical and socioeconomic constraints

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    Producción CientíficaA diversity of integrated assessment models (IAMs) coexists due to the different approaches developed to deal with the complex interactions, high uncertainties and knowledge gaps within the environment and human societies. This paper describes the open-source MEDEAS modeling framework, which has been developed with the aim of informing decision-making to achieve the transition to sustainable energy systems with a focus on biophysical, economic, social and technological restrictions and tackling some of the limitations identified in the current IAMs. MEDEAS models include the following relevant characteristics: representation of biophysical constraints to energy availability; modeling of the mineral and energy investments for the energy transition, allowing a dynamic assessment of the potential mineral scarcities and computation of the net energy available to society; consistent representation of climate change damages with climate assessments by natural scientists; integration of detailed sectoral economic structure (input–output analysis) within a system dynamics approach; energy shifts driven by physical scarcity; and a rich set of socioeconomic and environmental impact indicators. The potentialities and novel insights that this framework brings are illustrated by the simulation of four variants of current trends with the MEDEAS-world model: the consideration of alternative plausible assumptions and methods, combined with the feedback-rich structure of the model, reveal dynamics and implications absent in classical models. Our results suggest that the continuation of current trends will drive significant biophysical scarcities and impacts which will most likely derive in regionalization (priority to security concerns and trade barriers), conflict, and ultimately, a severe global crisis which may lead to the collapse of our modern civilization. Despite depicting a much more worrying future than conventional projections of current trends, we however believe it is a more realistic counterfactual scenario that will allow the design of improved alternative sustainable pathways in future work.Ministerio de Economía, Industria y Competitividad (Project CO2017-85110-R)Ministerio de Economía, Industria y Competitividad (Project JCI-2016–28833)MEDEAS project, funded by the European Union’s Horizon2020 research and innovation programme under grant agree-ment no. 691287.LOCOMOTION project, funded by the EuropeanUnion’s Horizon 2020 research and innovation programmeunder grant agreement no. 82110
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