3,581 research outputs found
The effect of core polarization on longitudinal form factors in B
Electron scattering Coulomb form factors for the single-particle quadrupole
transitions in -shell B nucleus have been studied. Core polarization
effects are included through a microscopic theory that includes excitations
from the core orbits up to higher orbits with 2 excitations. The
modified surface delta interaction (MSDI) is employed as a residual
interaction. The effect of core polarization is found essential in both the
transition strengths and momentum transfer dependence of form factors, and
gives a remarkably good agreement with the measured data with no adjustable
parameters.Comment: 4 pages, 5 figure
Longitudinal and Transverse Form Factors from C
Electron scattering form factors from C have been studied in the
framework of the particle-hole shell model. Higher configurations are taken
into account by allowing particle-hole excitations from the 1 and 1
shells core orbits up to the 1 shell. The inclusion of the higher
configurations modifies the form factors markedly and describes the
experimental data very well in all momentum transfer regions.Comment: 5 pages, 5 figures, 3 tables, late
Restricting paracetamol in the United Kingdom to reduce poisoning: a systematic review
Background Paracetamol poisoning is implicated in about 150-200 poisoning deaths per year in England and Wales. We review previous studies assessing the effectiveness of regulations introduced in 1998 to restrict sales of paracetamol and reduce paracetamol poisoning. Methods We searched the following electronic databases: MEDLINE, EMBASE, CINHAL, HIMIC, COCH, APC, CENTRAL and DARE. English language publications between 1998 and 2003 were included. Studies were included if they took place in the United Kingdom and assessed changes in any aspect of paracetamol poisoning following the introduction of the 1998 regulations. Results Twelve studies were identified, which examined several different outcomes. Three studies examined admissions to liver transplant units; all reported reductions. Eight studies evaluated severity of paracetamol poisoning; three reported reductions but five did not. Five out of six studies reported reductions in hospital admissions. One study reported reduced mortality in England and Wales after 1 year while another found no difference in Scotland 2 years after the regulations were introduced. Two studies observed a significant reduction in over-the-counter sales. Studies suffered from several limitations including short follow-up periods, no case definition for paracetamol poisoning and lack of comparison groups. Conclusions The limitations of these studies makes it difficult to draw firm conclusions. They do, however, suggest that the 1998 regulations may have been associated with reduced admissions to liver units and liver transplants, reduced hospital attendance due to paracetamol poisoning and reduced sales of paracetamol. Further research is needed to fully evaluate the impact of the 1998 regulations. In the future, formal evaluation of the impact of similar interventions should be an integral part of policy formation
Full -shell study of even-even Ti isotopes
The level schemes and transition rates {\em B}({\em E}2;) of
eve-even Ti isotopes were studied by performing large-scale shell
model calculations with FPD6 and GXPF1 effective interactions. Excellent
agreement were obtained by comparing the first 2 level for all isotopes
with the recently available experimental data, but studying the transition
strengths {\em B}({\em E}2; 0) for all Ti isotopes using
constant proton-neutron effective charges prove the limitations of the present
large-scale calculations to reproduce the experiment in detail.Comment: 4 pages, 4 figure
Multiplication theory for dynamically biased avalanche photodiodes: new limits for gain bandwidth product
Novel theory is developed for the avalanche multiplication process in avalanche photodiodes (APDs) under time-varying reverse-biasing conditions. Integral equations are derived characterizing the statistics of the multiplication factor and the impulse-response function of APDs, as well as their breakdown probability, all under the assumption that the electric field driving the avalanche process is time varying and spatially nonuniform. Numerical calculations generated by the model predict that by using a bit-synchronous sinusoidal biasing scheme to operate the APD in an optical receiver, the pulse-integrated gain-bandwidth product can be improved by a factor of 5 compared to the same APD operating under the conventional static biasing. The bit-synchronized periodic modulation of the electric field in the multiplication region serves to (1) produce large avalanche multiplication factors with suppressed avalanche durations for photons arriving in the early phase of each optical pulse; and (2) generate low avalanche gains and very short avalanche durations for photons arriving in the latter part of each optical pulse. These two factors can work together to reduce intersymbol interference in optical receivers without sacrificing sensitivity
Use of risk adjustment in setting budgets and measuring performance in primary care I: how it works
Summary points: Primary care groups and general practices will be funded largely through capitation based formulas, and their performance will be monitored more closely. Current methods of funding primary care trusts and general practices, and of monitoring their performance, do not take into account differences in case mix. Risk adjustment methods have been developed in the United States to allow measurement ofcase mix and morbidity of primary care populations. Risk adjustment methods are now being used to set capitation rates for health services in the United States
Ethnic group differences in overweight and obese children and young people in England: cross sectional survey
Aims: To determine the percentage of children and young adults who are obese or overweight within different ethnic and socioeconomic groups.Methods: Secondary analysis of data on 5689 children and young adults aged 2 - 20 years from the 1999 Health Survey for England.Results: Twenty three per cent of children (n = 1311) were overweight, of whom 6% ( n = 358) were obese. More girls than boys were overweight ( 24% v 22%). Afro-Caribbean girls were more likely to be overweight ( odds ratio 1.73, 95% CI 1.29 to 2.33), and Afro-Caribbean and Pakistani girls were more likely to be obese than girls in the general population ( odds ratios 2.74 ( 95% CI 1.74 to 4.31) and 1.71 ( 95% CI 1.06 to 2.76), respectively). Indian and Pakistani boys were more likely to be overweight ( odds ratios 1.55 ( 95% CI 1.12 to 2.17) and 1.36 ( 95% CI 1.01 to 1.83), respectively). There were no significant differences in the prevalence of obese and overweight children from different social classes.Conclusion: The percentage of children and young adults who are obese and overweight differs by ethnic group and sex, but not by social class. British Afro-Caribbean and Pakistani girls have an increased risk of being obese and Indian and Pakistani boys have an increased risk of being overweight than the general population. These individuals may be at greater combined cumulative risk of morbidity and mortality from cardiovascular disease and so may be a priority for initiatives to target groups of children at particular risk of obesity
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