58 research outputs found
Color confinement and dual superconductivity of the vacuum. III
It is demonstrated that monopole condensation in the confined phase of SU(2)
and SU(3) gauge theories is independent of the specific Abelian projection used
to define the monopoles. Hence the dual excitations which condense in the
vacuum to produce confinement must have magnetic U(1) charge in all the Abelian
projections. Some physical implications of this result are discussed.Comment: 6 pages, 5 postscript figure
Dung removal increases under higher dung beetle functional diversity regardless of grazing intensification
Dung removal by macrofauna such as dung beetles is an important process for nutrient cycling in pasturelands. Intensification of farming practices generally reduces species and functional diversity of terrestrial invertebrates, which may negatively affect ecosystem services. Here, we investigate the effects of cattle-grazing intensification on dung removal by dung beetles in field experiments replicated in 38 pastures around the world. Within each study site, we measured dung removal in pastures managed with low- and high-intensity regimes to assess between-regime differences in dung beetle diversity and dung removal, whilst also considering climate and regional variations. The impacts of intensification were heterogeneous, either diminishing or increasing dung beetle species richness, functional diversity, and dung removal rates. The effects of beetle diversity on dung removal were more variable across sites than within sites. Dung removal increased with species richness across sites, while functional diversity consistently enhanced dung removal within sites, independently of cattle grazing intensity or climate. Our findings indicate that, despite intensified cattle stocking rates, ecosystem services related to decomposition and nutrient cycling can be maintained when a functionally diverse dung beetle community inhabits the human-modified landscape
Cardiovascular disease, chronic kidney disease, and diabetes mortality burden of cardiometabolic risk factors from 1980 to 2010: a comparative risk assessment
Background High blood pressure, blood glucose, serum cholesterol, and BMI are risk factors for cardiovascular
diseases and some of these factors also increase the risk of chronic kidney disease and diabetes. We estimated mortality from cardiovascular diseases, chronic kidney disease, and diabetes that was attributable to these four
cardiometabolic risk factors for all countries and regions from 1980 to 2010.
Methods We used data for exposure to risk factors by country, age group, and sex from pooled analyses of populationbased health surveys. We obtained relative risks for the eff ects of risk factors on cause-specifi c mortality from metaanalyses
of large prospective studies. We calculated the population attributable fractions for- each risk factor alone,
and for the combination of all risk factors, accounting for multicausality and for mediation of the eff ects of BMI by the other three risks. We calculated attributable deaths by multiplying the cause-specifi c population attributable fractions by the number of disease-specifi c deaths. We obtained cause-specifi c mortality from the Global Burden of Diseases, Injuries, and Risk Factors 2010 Study. We propagated the uncertainties of all the inputs to the fi nal estimates.
Findings In 2010, high blood pressure was the leading risk factor for deaths due to cardiovascular diseases, chronic kidney disease, and diabetes in every region, causing more than 40% of worldwide deaths from these diseases; high BMI and glucose were each responsible for about 15% of deaths, and high cholesterol for more than 10%. After
accounting for multicausality, 63% (10\ub78 million deaths, 95% CI 10\ub71\u201311\ub75) of deaths from these diseases in 2010 were attributable to the combined eff ect of these four metabolic risk factors, compared with 67% (7\ub71 million deaths,
6\ub76\u20137\ub76) in 1980. The mortality burden of high BMI and glucose nearly doubled from 1980 to 2010. At the country
level, age-standardised death rates from these diseases attributable to the combined eff ects of these four risk factors
surpassed 925 deaths per 100 000 for men in Belarus, Kazakhstan, and Mongolia, but were less than 130 deaths per 100 000 for women and less than 200 for men in some high-income countries including Australia, Canada, France,
Japan, the Netherlands, Singapore, South Korea, and Spain.
Interpretation The salient features of the cardiometabolic disease and risk factor epidemic at the beginning of
the 21st century are high blood pressure and an increasing eff ect of obesity and diabetes. The mortality burden
of cardiometabolic risk factors has shifted from high-income to low-income and middle-income countries. Lowering
cardiometabolic risks through dietary, behavioural, and pharmacological interventions should be a part of the globalresponse to non-communicable diseases
Production Costs, Congestion, Scope and Scale Economies in Urban Bus Transportation Corridors
This paper examines the main characteristics of production costs of urban bus transportation services by developing a microeconomic cost model that considers only the factors provided by bus operators. A multiproduct formulation is used that regards trips during peak and off peak periods as different products. The influence of the demand structure and congestion in the production of trips are considered in the analysis. Production and cost functions are specified using a fix proportion technology. The characteristics of scale and scope economies are studied with and without congestion. A numerical example is presented to illustrate the results. It was found that in the short run the existence of fixed costs produce ray scale economies. For a given fleet, the degree of these ray scale economies will increase with the magnitude of fixed costs and will decrease when the level of total production increases. In the long run, economies of scale are produced only by administration fixed expenditures, which can also increase more proportionally than production after some production level. Without congestion, there are constant product-specific returns to scale for trips produced in all non-peak periods. However, there are product specific diseconomies for the peak period
Demand responsive urban public transport system design: Methodology and application
In this paper, the authors present a methodology for solving the Public Transport Network Design Problem (PTNDP) and describe its application in the context of the Design Study developed in order to propose a new structure for the transit system of the city of Santiago, Chile. First, the authors briefly define the PTNDP as a multilevel programming problem and discuss the solution method implemented. Then, the application of this methodology to the Santiago transit system is presented, and the main results obtained are analyzed. The new restructured system, based on a hierarchy of specialized services that complement and coordinate their operations and using an integrated fare scheme, is compared with an optimized version (optimal frequencies) of the current one, a set of direct services, mainly based on the operation of independent itineraries, without fare integration. The most important conclusions are the following: (a) the private operating costs and the social costs of the restructured system, using higher standard buses, are considerably lower than the costs of the current system; (b) these cost reductions allow government authorities to introduce an important number of modernizing measures without subsidies and fare increases
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