653 research outputs found
Polyphase exhumation in the western Qinling Mountains, China: Rapid Early Cretaceous cooling along a lithospheric-scale tear fault and pulsed Cenozoic uplift
No full textAbstractThe western sector of the Qinling–Dabie orogenic belt plays a key role in both Late Jurassic to Early Cretaceous “Yanshanian” intracontinental tectonics and Cenozoic lateral escape triggered by India–Asia collision. The Taibai granite in the northern Qinling Mountains is located at the westernmost tip of a Yanshanian granite belt. It consists of multiple intrusions, constrained by new Late Jurassic and Early Cretaceous U–Pb zircon ages (156±3Ma and 124±1Ma). Applying various geochronometers (40Ar/39Ar on hornblende, biotite and K-feldspar, apatite fission-track, apatite [U–Th–Sm]/He) along a vertical profile of the Taibai Mountain refines the cooling and exhumation history. The new age constraints record the prolonged pre-Cenozoic intracontinental deformation as well as the cooling history mostly related to India–Asia collision. We detected rapid cooling for the Taibai granite from ca. 800 to 100°C during Early Cretaceous (ca. 123 to 100Ma) followed by a period of slow cooling from ca. 100Ma to ca. 25Ma, and pulsed exhumation of the low-relief Cretaceous peneplain during Cenozoic times. We interpret the Early Cretaceous rapid cooling and exhumation as a result from activity along the southern sinistral lithospheric scale tear fault of the recently postulated intracontinental subduction of the Archean/Palaeoproterozoic North China Block beneath the Alashan Block. A Late Oligocene to Early Miocene cooling phase might be triggered either by the lateral motion during India–Asia collision and/or the Pacific subduction zone. Late Miocene intensified cooling is ascribed to uplift of the Tibetan Plateau
Estimating the effect of recurrent infectious diseases on nutritional status: sampling frequency, sample-size, and bias.
No full textThere is an ongoing interest in studying the effect of common recurrent infections and conditions, such as diarrhoea, respiratory infections, and fever, on the nutritional status of children at risk of malnutrition. Epidemiological studies exploring this association need to measure infections with sufficient accuracy to minimize bias in the effect estimates. A versatile model of common recurrent infections was used for exploring how many repeated measurements of disease are required to maximize the power and logistical efficiency of studies investigating the effect of infectious diseases on malnutrition without compromising the validity of the estimates. Depending on the prevalence and distribution of disease within a population, 15-30 repeat measurements per child over one year should be sufficient to provide unbiased estimates of the association between infections and nutritional status. Less-frequent measurements lead to a bias in the effect size towards zero, especially if disease is rare. In contrast, recall error can lead to exaggerated effect sizes. Recall periods of three days or shorter may be preferable compared to longer recall periods. The results showed that accurate estimation of the association between recurrent infections and nutritional status required closer follow-up of study participants than studies using recurrent infections as an outcome measure. The findings of the study provide guidance for choosing an appropriate sampling strategy to explore this association
Výzkum regionálního trhu tiskovin s cílem navrhnout řešení k posílení pozice Moravskoslezského večerníku na trhu OSNA a. s.
No full textImport 21/04/200
Epidemiological methods in diarrhoea studies--an update.
No full textBACKGROUND: Diarrhoea remains a leading cause of morbidity and mortality but is difficult to measure in epidemiological studies. Challenges include the diagnosis based on self-reported symptoms, the logistical burden of intensive surveillance and the variability of diarrhoea in space, time and person. METHODS: We review current practices in sampling procedures to measure diarrhoea, and provide guidance for diarrhoea measurement across a range of study goals. Using 14 available data sets, we estimated typical design effects for clustering at household and village/ neighbourhood level, and measured the impact of adjusting for baseline variables on the precision of intervention effect estimates. RESULTS: Incidence is the preferred outcome measure in aetiological studies, health services research and vaccine trials. Repeated prevalence measurements (longitudinal prevalence) are appropriate in high-mortality settings where malnutrition is common, although many repeat measures are rarely useful. Period prevalence is an inadequate outcome if an intervention affects illness duration. Adjusting point estimates for age or diarrhoea at baseline in randomized trials has little effect on the precision of estimates. Design effects in trials randomized at household level are usually <2 (range 1.0–3.2). Design effects for larger clusters (e.g. villages or neighbourhoods) vary greatly among different settings and study designs (range 0.1–25.8). CONCLUSIONS: Using appropriate sampling strategies and outcome measures can improve the efficiency, validity and comparability of diarrhoea studies. Allocating large clusters in cluster randomized trials is compromized by unpredictable design effects and should be carried out only if the research question requires it
The synthesis and separation of meso-tetra-p-chlorophenyl-porphyrin and its divalent metallo-complexes by reverse-phase high performance liquid chromatography
No full textThis thesis describes the separation of meso-tetra-p-chlorophenylporphyrin and its divalent metal complexes by non-aqueous reverse-phase HPLC. The separation attempt uses a systematic and practical approach based on fundamental relationships in liquid chromatography. By varying the three parameters, separation selectivity, ∝, number of theoretical plates, N, and capacity factor, k', optimal resolution of these compounds is achieved
Taxing capital income in Hungary and the European Union
No full textCountries seeking membership in the European Union (EU) cannot look to the EU for a blueprint for reforming their system for taxing capital income. Indeed, it is hard to generalize about tax systems in the EU. Most member states apply fairly low tax rates to interest payments and discriminate against profit distributions. But tax rates, exemption levels, and methods of tax integration differ greatly within and across countries, and there is almost no harmonization of methods for taxing capital income. Approaches to taxing capital gains vary greatly, and distortions arise from the treatment of various sources of capital income. In 1993, when the EU began efforts to integrate capital markets, member countries proposed various ways to harmonize capital income taxes, including a proposal to introduce a withholding tax on interest income of residents of member states, with a minimum rate of 15 percent (revised to 10 percent). Under this scheme all interest on bank deposits and government and private bonds would be taxed and there might also be a final withholding tax on residents interest income. But the proposal was not accepted and the EU Commission decided to maintain the status quo, not to pressure member countries to harmonize company taxes. But Hungary could look for models in the Nordic countries (especially Norway and Sweden), Austria, and Finland, which have undertaken far-reaching reforms of capital income taxation. In most EU countries capital gains are either not (directly) taxed or are not taxed systematically. In Finland and Norway identical tax rates are applied to all types of capital income, including capital gains. The centerpiece of the"Scandinavian model"is a dual income tax, combining a progressive tax on personal income with a flat-rate tax on all types of capital income. The"Scandinavian model"contrasts sharply with the"comprehensive income taxation"model, under which a single (progressive) tax schedule is applied to income from all sources. In Austria the treatment of different types of capital income is relatively uniform but the composite tax burden on capital income resembles the highest personal income tax rate rather than a reduced rate. Austria's rate of tax evasion was high, but a 10 percent withholdingtax applied to all interest-bearing assets has reduced discrimination against honest taxpayers.Economic Theory&Research,Public Sector Economics&Finance,International Terrorism&Counterterrorism,Environmental Economics&Policies,Payment Systems&Infrastructure,Economic Theory&Research,Environmental Economics&Policies,Public Sector Economics&Finance,International Terrorism&Counterterrorism,Banks&Banking Reform
Status and new developments of the Generator Services
No full textThe Generator Services (GENSER) provide ready-to-use Monte Carlo generators, compiled on multiple platforms or ready to be compiled, for the LHC experiments. In this paper we discuss the recent developments in the build machinery, which allowed to fully automatize the installation process. The new system is based on and is integrated entirely with the 'LCG external software' infrastructure, providing all the external packages needed by the LHC experiments
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Physics of the top quark at D0 new measurement of the production cross section and mass
No full textWe present a measurement of the t{anti t} production cross section in p{anti p} collisions at {radical}s = 1.8 TeV and a measurement of top quark mass m{sub t} by the D0 experiment at the Fermilab Tevatron. The measurements are based on the data from the 1992- 1996 run during which the D0 detector was exposed to the integrated luminosity of approximately 125 pb{sup -1}. We observe 39 t{anti t} candidate events in the dilepton and lepton+jets decay channels with an expected background of 13.7 {+-} 2.2 events. We measure the top quark mass m{sub t} using a two constraint fit to m{sub t} in t{anti t} {yields} bW{sup +} {anti b}W{sup -} final states with one W decaying to q{anti q} and the other to e{nu} or {mu}{nu}. Events are binned in the fit mass versus a measure of probability for events to be the signal rather than a background. Likelihood fits to the data yield m{sub t} = 173.3 {+-} 5.6 (stat) {+-} 6.2 (syst) GeV/c{sup 2}. For this mass we measure the t{anti t} production cross section to be 5.5 {+-} 1.8 pb
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