Surface metal-insulator transition in the Hubbard model

The correlation-driven metal-insulator (Mott) transition at a solid surface is studied within the Hubbard model for a semi-infinite lattice by means of the dynamical mean-field theory. The transition takes place at a unique critical strength of the interaction. Depending on the surface geometry, the interaction strength and the wave vector, we find one-electron excitations in the coherent part of the surface-projected metallic spectrum which are confined to two dimensions.Comment: LaTeX, 9 pages, 5 eps figures included, Phys. Rev. B (in press

WMO Assessment of Weather and Climate Mortality Extremes: Lightning, Tropical Cyclones, Tornadoes, and Hail

A World Meteorological Organization (WMO) Commission for Climatology international panel was convened to examine and assess the available evidence associated with five weather-related mortality extremes: 1) lightning (indirect), 2) lightning (direct), 3) tropical cyclones, 4) tornadoes, and 5) hail. After recommending for acceptance of only events after 1873 (the formation of the predecessor of the WMO), the committee evaluated and accepted the following mortality extremes: 1) “highest mortality (indirect strike) associated with lightning” as the 469 people killed in a lightning-caused oil tank fire in Dronka, Egypt, on 2 November 1994; 2) “highest mortality directly associated with a single lightning flash” as the lightning flash that killed 21 people in a hut in Manica Tribal Trust Lands, Zimbabwe (at time of incident, eastern Rhodesia), on 23 December 1975; 3) “highest mortality associated with a tropical cyclone” as the Bangladesh (at time of incident, East Pakistan) cyclone of 12–13 November 1970 with an estimated death toll of 300 000 people; 4) “highest mortality associated with a tornado” as the 26 April 1989 tornado that destroyed the Manikganj district, Bangladesh, with an estimated death toll of 1300 individuals; and 5) “highest mortality associated with a hailstorm” as the storm occurring near Moradabad, India, on 30 April 1888 that killed 246 people. These mortality extremes serve to further atmospheric science by giving baseline mortality values for comparison to future weather-related catastrophes and also allow for adjudication of new meteorological information as it becomes available

A predictive model relating daily fluctuations in summer temperatures and mortality rates

<p>Abstract</p> <p>Background</p> <p>In the context of climate change, an efficient alert system to prevent the risk associated with summer heat is necessary. The authors' objective was to describe the temperature-mortality relationship in France over a 29-year period and to define and validate a combination of temperature factors enabling optimum prediction of the daily fluctuations in summer mortality.</p> <p>Methods</p> <p>The study addressed the daily mortality rates of subjects aged over 55 years, in France as a whole, from 1975 to 2003. The daily minimum and maximum temperatures consisted in the average values recorded by 97 meteorological stations. For each day, a cumulative variable for the maximum temperature over the preceding 10 days was defined.</p> <p>The mortality rate was modelled using a Poisson regression with over-dispersion and a first-order autoregressive structure and with control for long-term and within-summer seasonal trends. The lag effects of temperature were accounted for by including the preceding 5 days. A "backward" method was used to select the most significant climatic variables. The predictive performance of the model was assessed by comparing the observed and predicted daily mortality rates on a validation period (summer 2003), which was distinct from the calibration period (1975–2002) used to estimate the model.</p> <p>Results</p> <p>The temperature indicators explained 76% of the total over-dispersion. The greater part of the daily fluctuations in mortality was explained by the interaction between minimum and maximum temperatures, for a day <it>t </it>and the day preceding it. The prediction of mortality during extreme events was greatly improved by including the cumulative variables for maximum temperature, in interaction with the maximum temperatures. The correlation between the observed and estimated mortality ratios was 0.88 in the final model.</p> <p>Conclusion</p> <p>Although France is a large country with geographic heterogeneity in both mortality and temperatures, a strong correlation between the daily fluctuations in mortality and the temperatures in summer on a national scale was observed. The model provided a satisfactory quantitative prediction of the daily mortality both for the days with usual temperatures and for the days during intense heat episodes. The results may contribute to enhancing the alert system for intense heat waves.</p

Public Health-Related Impacts of Climate Change in California

In June 2005 Governor Arnold Schwarzenegger issued Executive Order S-3-05 that set greenhouse gas emission reduction targets for California, and directed the Secretary of the California Environmental Protection Agency to report to the governor and the State legislature by January 2006 and biannually thereafter on the impacts to California of global warming, including impacts to water supply, public health, agriculture, the coastline, and forestry, and to prepare and report on mitigation and adaptation plans to combat these impacts. This report is a part of the report to the governor and legislature, and focuses on public health impacts that have been associated with climate change. Considerable evidence suggests that average ambient temperature is increasing worldwide, that temperatures will continue to increase into the future, and that global warming will result in changes to many aspects of climate, including temperature, humidity, and precipitation (McMichael and Githeko, 2001). It is expected that California will experience changes in both temperature and precipitation under current trends. Many of the changes in climate projected for California could have ramifications for public health (McMichael and Githeko, 2001), and this document summarizes the impacts judged most likely to occur in California, based on a review of available peer-reviewed scientific literature and new modeling and statistical analyses. The impacts identified as most significant to public health in California include mortality and morbidity related to temperature, air pollution, vector and water-borne diseases, and wildfires. There is considerable complexity underlying the health of a population with many contributing factors including biological, ecological, social, political, and geographical. In addition, the relationship between climate change and changes in public health is difficult to predict for the most part, although more detailed information is available on temperature-related mortality and air pollution effects than the other endpoints discussed in this document. Consequently, these two topics are discussed in greater detail. Where possible, estimates of the magnitude and significance of these impacts are also discussed, along with possible adaptations that could reduce climate-related health impacts. In the context of this review, weather refers to meteorological conditions at a specific place and time over a relatively short time frame, such as up to a year or two. Climate, on the other hand, refers to the same meteorological conditions, but over a longer time frame, such as decades or centuries

Double Beta Decay: Historical Review of 75 Years of Research

Main achievements during 75 years of research on double beta decay have been reviewed. The existing experimental data have been presented and the capabilities of the next-generation detectors have been demonstrated.Comment: 25 pages, typos adde

Emissions pathways, climate change, and impacts on California

The magnitude of future climate change depends substantially on the greenhouse gas emission pathways we choose. Here we explore the implications of the highest and lowest Intergovernmental Panel on Climate Change emissions pathways for climate change and associated impacts in California. Based on climate projections from two state-of-the-art climate models with low and medium sensitivity (Parallel Climate Model and Hadley Centre Climate Model, version 3, respectively), we find that annual temperature increases nearly double from the lower B1 to the higher A1fi emissions scenario before 2100. Three of four simulations also show greater increases in summer temperatures as compared with winter. Extreme heat and the associated impacts on a range of temperature-sensitive sectors are substantially greater under the higher emissions scenario, with some interscenario differences apparent before midcentury. By the end of the century under the B1 scenario, heatwaves and extreme heat in Los Angeles quadruple in frequency while heat-related mortality increases two to three times; alpine subalpine forests are reduced by 50–75%; and Sierra snowpack is reduced 30–70%. Under A1fi, heatwaves in Los Angeles are six to eight times more frequent, with heat-related excess mortality increasing five to seven times; alpine subalpine forests are reduced by 75–90%; and snowpack declines 73–90%, with cascading impacts on runoff and streamflow that, combined with projected modest declines in winter precipitation, could fundamentally disrupt California’s water rights system. Although interscenario differences in climate impacts and costs of adaptation emerge mainly in the second half of the century, they are strongly dependent on emissions from preceding decades

Effect modification of air pollution on Urinary 8-Hydroxy-2'-Deoxyguanosine by genotypes: an application of the multiple testing procedure to identify significant SNP interactions

<p>Abstract</p> <p>Background</p> <p>Air pollution is associated with adverse human health, but mechanisms through which pollution exerts effects remain to be clarified. One suggested pathway is that pollution causes oxidative stress. If so, oxidative stress-related genotypes may modify the oxidative response defenses to pollution exposure.</p> <p>Methods</p> <p>We explored the potential pathway by examining whether an array of oxidative stress-related genes (twenty single nucleotide polymorphisms, SNPs in nine genes) modified associations of pollutants (organic carbon (OC), ozone and sulfate) with urinary 8-hydroxy-2-deoxygunosine (8-OHdG), a biomarker of oxidative stress among the 320 aging men. We used a Multiple Testing Procedure in R modified by our team to identify the significance of the candidate genes adjusting for <it>a priori </it>covariates.</p> <p>Results</p> <p>We found that glutathione S-tranferase P1 (GSTP1, rs1799811), M1 and catalase (rs2284367) and group-specific component (GC, rs2282679, rs1155563) significantly or marginally significantly modified effects of OC and/or sulfate with larger effects among those carrying the wild type of GSTP1<it/>, catalase, non-wild type of <it>GC </it>and the non-null of GSTM1.</p> <p>Conclusions</p> <p>Polymorphisms of oxidative stress-related genes modified effects of OC and/or sulfate on 8-OHdG, suggesting that effects of OC or sulfate on 8-OHdG and other endpoints may be through the oxidative stress pathway.</p