12,757 research outputs found
Semi-inclusive charged-current neutrino-nucleus reactions
The general, universal formalism for semi-inclusive charged-current
(anti)neutrino-nucleus reactions is given for studies of any hadronic system,
namely, either nuclei or the nucleon itself. The detailed developments are
presented with the former in mind and are further specialized to cases where
the final-state charged lepton and an ejected nucleon are presumed to be
detected. General kinematics for such processes are summarized and then
explicit expressions are developed for the leptonic and hadronic tensors
involved and for the corresponding responses according to the usual charge,
longitudinal and transverse projections, keeping finite the masses of all
particles involved. In the case of the hadronic responses, general symmetry
principles are invoked to determine which contributions can occur. Finally, the
general leptonic-hadronic tensor contraction is given as well as the cross
section for the process
Coincidence charged-current neutrino-induced deuteron disintegration
Deuteron disintegration by charged-current neutrino (CC) scattering
offers the possibility to determine the energy of the incident neutrino by
measuring in coincidence two of the three resulting particles: a charged lepton
(usually a muon) and two protons, where we show that this channel can be
isolated from all other, for instance, from those with a pion in the final
state. We discuss the kinematics of the process for several detection
scenarios, both in terms of kinematic variables that are natural from a
theoretical point of view and others that are better matched to experimental
situations. The deuteron structure is obtained from a relativistic model
(involving an approximation to the Bethe-Salpeter equation) as an extension of
a previous, well-tested model used in deuteron electrodisintegration. We
provide inclusive and coincidence (semi-inclusive) cross sections for a variety
of kinematic conditions, using the plane-wave impulse approximation,
introducing final-state hadronic exchange terms (plane-wave Born approximation)
and final-state hadronic interactions (distorted-wave Born approximation).Comment: 31 pages, 14 figure
Studying the Child Obesity Epidemic with Natural Experiments
We utilize clinical records of successive visits by children to pediatric clinics in Indianapolis to estimate the effects on their body mass of environmental changes near their homes. We compare results for fixed-residence children with those for cross-sectional data. Our environmental factors are fast food restaurants, supermarkets, parks, trails, and violent crimes, and 13 types of recreational amenities derived from the interpretation of annual aerial photographs. We looked for responses to these factors changing within buffers of 0.1, 0.25, 0.5, and 1 mile. We found that cross-sectional estimates are quite different from the Fixed Effects estimates of the impacts of amenities locating near a child. In cross section nearby fast food restaurants were associated with higher BMI and supermarkets with lower BMI. These results were reversed in the FE estimates. The recreational amenities that appear to lower children's BMI were fitness areas, kickball diamonds, and volleyball courts. We estimated that locating these amenities near their homes could reduce the weight of an overweight eight-year old boy by 3 to 6 pounds
Emotional disorder and absence from school: Findings from the 2004 British Child and Adolescent Mental Health Survey
This is the final version. Available on open access from Springer via the DOI in this recordBackground
Emotional disorder may be associated with absence from school, but the existing evidence is
methodologically weak. We studied the relationships between anxiety, depression and emotional
difficulties, and school absence (total, authorised and unauthorised) using data from the 2004 British
Child and Adolescent Mental Health Survey (BCAMHS).
Method
The BCAMHS was a cross-sectional, community survey of 7977 five to 16 year olds. Emotional
disorder was assessed using the Development and Wellbeing Assessment (DAWBA), and emotional
difficulties using the Strengths and Difficulties Questionnaire (SDQ) completed by teachers and
parents. Teachers reported days absent in the previous school term. Multivariable negative binomial
regression was used to examine the impact of emotional disorder and difficulties on absence. Age,
gender and general health were explored as moderators.
Results
Anxiety, depression and emotional difficulties were associated with higher rates of all types of
absence (rate ratios for total absence: anxiety 1.69 (1.39 to 2.06) p<0.001; depression 3.40 (2.46 to
4.69) p<0.001; parent-reported emotional difficulties 1.07 (1.05 to 1.10) p<0.001; teacher-reported
emotional difficulties 1.10 (1.08 to 1.13) p<0.001). The strongest association was observed for
depression and unauthorised absence. Relationships were stronger for secondary compared to
primary school children.
Conclusions
Health and educational professionals should be aware that children with poor attendance may be
experiencing emotional ill health, regardless of absence type. Absence may provide a useful tool to
identify those who require additional mental health support. Findings highlight the widespread
burden of emotional disorder and the need to support those with emotional ill health in continuing
to access education.University of ExeterWellcome TrustNational Institute for Health Research (NIHR
Exposure to violence and PTSD symptoms among Somali women
Posttraumatic stress disorder (PTSD) symptoms, exposure to traumatic stressors, and health care utilization were examined in 84 women attending a primary health care clinic in Mogadishu, Somalia. The Somalia-Posttraumatic Diagnostic Scale was used in this active warzone to measure symptoms. Nearly all women reported high levels of confrontations with violence; half described being exposed to a potentially traumatizing event. Nearly one third had significant PTSD symptoms. Compared to those who did not, women who reported exposure to a traumatic stressor reported more confrontations with violence (7.1 vs. 3.3; p < . 001), health complaints (3.8 vs. 2.9; p = .03), and nearly 3 times as much (p = .03) health service utilization. A potentially traumatizing event was found to be a simplified proxy for assessing mental health distress in women attending a primary health care facility in highly insecure, unpredictable, resource-limited settings
Assessment of the Potential Impact and Cost-effectiveness of Self-Testing for HIV in Low-Income Countries.
Studies have demonstrated that self-testing for human immunodeficiency virus (HIV) is highly acceptable among individuals and could allow cost savings, compared with provider-delivered HIV testing and counseling (PHTC), although the longer-term population-level effects are uncertain. We evaluated the cost-effectiveness of introducing self-testing in 2015 over a 20-year time frame in a country such as Zimbabwe
Quantum measurement and decoherence
Distribution functions defined in accord with the quantum theory of
measurement are combined with results obtained from the quantum Langevin
equation to discuss decoherence in quantum Brownian motion. Closed form
expressions for wave packet spreading and the attenuation of coherence of a
pair of wave packets are obtained. The results are exact within the context of
linear passive dissipation. It is shown that, contrary to widely accepted
current belief, decoherence can occur at high temperature in the absence of
dissipation. Expressions for the decoherence time with and without dissipation
are obtained that differ from those appearing in earlier discussions
- …