Inter-W Bose-Einstein Correlations ... or Not?

A critical summary is given of the present status of the study of Bose-Einstein Correlations in W-pair production at LEP II. In particular, the evidence is reviewed for or against the existence of Bose-Einstein correlations between pions originating both from a different of the two W's. If present, such an inter-W interference would not only form a potential bias in the determination of the W mass, but also would provide a laboratory to measure the space-time development of the overlap. If absent, this would drastically change the conventional (Hanbury Brown and Twiss) picture of pion interferometry in high energy physics.Comment: The contribution to the proceedings of the XXXth International Symposium on Multiparticle Dynamics, ISMD2000, Tihany, Hungar

Efficiency and equity considerations in modeling inter-sectoral water demand in South Africa

Empirical studies have shown that while global per capita freshwater availability is declining, competition among production sectors for the withdrawal of this resource is rapidly increasing. This situation is exacerbated by the rapid population growth especially in developing countries, urbanization, industrialization, externality problems, environmental sustainability and the need to increase food production. At country specific levels, policies have been designed to institute water use efficiency, equity and sustainability. The need to promote sectoral water use efficiency from the demand-side management requires a study to investigate the responsiveness of different production sectors and sub-sectors to variations in water prices. In most instances however, efficient water allocation compromises social equity, especially in a country where there is widespread poverty and where the gap between the rich and the poor is so wide that policies aimed at promoting economic growth should be carefully investigated to find whether efficient water allocation can also address the issue of equity among the different population groups. Review of empirical literature on the econometric approaches to sectoral water demand analysis shows that the agriculture sector has the least marginal value of water compared with the manufacturing, mining and services sectors. Based on this evidence it can be hypothesized that water reallocation from the agriculture to the non-agriculture sectors in South Africa can lead to growth in sectoral output. However, in a country where there is a wide gap between the rich and the poor, equity issues are high on the development agenda. Therefore, the benefits derived from efficient water reallocation should be equitably distributed to improve the standard of living of the critical population. Hence, the second hypothesis is that water reallocation from the agriculture to the non-agriculture sector can lead to an increase in the income of the critical population. To investigate these hypotheses the study: estimated the sectoral water demand functions and marginal values, used both social accounting matrix multiplier and computable general equilibrium analysis to investigate the impact of water reallocation from the agriculture to the non-agriculture sectors on output, factor payments on households’ welfare and analyzed the households’ welfare of the impact of global change on water resources in South Africa. The study used the Global Trade Analysis Project (GTAP) and United Nations Industrial Development Organization (UNIDO) data, and adopted the marginal productivity approach, and the two-stage model to estimate the global sectoral water demand functions and marginal values for thirteen sectors. This model is extended to the sectoral water demand analysis in South Africa. Thus, to validate the results of the global model, the study estimated sectoral water demand functions in South Africa by extracting data from STATSSA’s census of manufacturing and agricultural and services activities, published for each of the nine provinces in South Africa and the 2002 water supply and use accounts published by the same institution. The study tests the policy relevance of the computed marginal values for South Africa by using these values to investigate the impact of reallocating water from the agriculture to the non-agriculture sectors on output growth, value added, employment and households’ income generation.. To accomplish this objective, the study updates the 1999 social accounting matrix (SAM) for South Africa to reflect 2003 entries, computes the required multipliers and uses these to find how water reallocation on the basis of efficiency impacts sectoral output, households income generation and distribution. However, SAM multiplier analyses assume linearity, factor immobility and constant prices. The study therefore uses the computable general equilibrium analysis to investigate the households’ welfare implications of sectoral water reallocation and reduction due to global change. The SAM multiplier analysis shows that reallocation of water from the agriculture to the non-agriculture sectors leads to decrease in the output of the agriculture and the highly inter-dependent sectors. Specifically, output declines in the agriculture, food, beverages and tobacco and the services sectors, while it increases in the other sectors. However, if more than ten percent of the agriculture sector’s water is reallocated to the non-agriculture sector, net output declines, implying that the decline in output in the agriculture, food, beverages and tobacco and services sectors is more than the increase in output in the other sectors. This has consequences for factor remuneration, employment and households’ income. The above decline in the agriculture sector’s output leads to net job losses. Specifically the jobs lost in the agriculture sector are not countered by jobs created in the other sectors that benefit from the water reallocation. This is due to the fact that there are differences in skills requirements by the sectors. While the agriculture sector employs most of the unskilled workers, the other sectors require more medium and highly skilled individuals. This is reflected by changes in the wages paid to labourers. While the wages of unskilled labourers decline, there is an increase in the wages of medium and highly skilled labourers. The simulation results of the computable general equilibrium analysis show that sectoral water reallocation and reduction adversely impact the least and low-income households’ welfare, while improving the welfare of the high-income households. The interpretation is that with water reallocation or reduction, capital is substituted for water in the non-agriculture sectors and this increases the interest paid on capital, which goes to high-income households who are the owners of the capital. The adverse consequence can be reduced if food consumption by the poor households is maintained. To do this, some welfare measures are necessary. One such measure is the distribution of food stamps to the poor households.Thesis (PhD (Environmental Economics))--University of Pretoria, 2008.Agricultural Economics, Extension and Rural Developmentunrestricte

Heart Failure Predictors in a Group of Patients with Myocardial Infarction

AIM: The present study considers of the prevalence of heart failure (HF) in patients suffering from acute myocardial infarction (AMI) in the University Hospital Centre of Tirana (UHCT) “Mother Theresaâ€; the demographic and clinical characteristics of the sample during hospitalization; and the main predictors of heart failure occurrence inside the group of patients suffering an AMI.MATERIAL AND METHODS: During a period of study from 2013-2015 we studied demographic and clinical data from 587 consecutive patients presenting with AMI; Framingham criteria were adopted for classifying patients with HF upon admission.RESULTS: A Killip class ≥ 2 was the main diagnostic criterion of HF during hospitalisation. HF was identified in 156 patients (26.6%). The subgroup with HF had significant differences when compared with the other patients with regard to age, sex (male), heart rate upon admission, systolic blood pressure on admission, previous episodes of AMI, glycemia on admission, previous antihypertensive treatment, previous revascularization procedures, peripheral vascular disease, chronic renal disease, ejection fraction (EF), anemia, and atrial fibrillation presence. Independent predictors for HF occurrence in the logistic regression model were EF, previous revascularization, peripheral vascular disease, age, sex, previous AMI, systolic blood pressure upon admission, and anaemia.CONCLUSION: As a conclusion, HF seems to be a common occurrence after AMI, in spite of changes in the epidemiological profile of the acute coronary syndrome. An increase in the incidence is registered as well, parallel to a decrease in the mortality following AMI. Attention must be shown for highly risked subpopulations, aged persons, patients with the previous coronary disease, and concomitant conditions

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements