60 research outputs found
Weak decays of 4He-Lambda
We measured the lifetime and the mesonic and non-mesonic decay rates of the
4He-Lambda hypernucleus. The hypernuclei were created using a 750 MeV/c
momentum K- beam on a liquid 4He target by the reaction 4He(K-,pi-)4He-Lambda.
The 4He-Lambda lifetime was directly measured using protons from Lambda p -> n
p non-mesonic decay (also referred to as proton-stimulated decay) and was found
to have a value of tau = 245 +/- 24 ps. The mesonic decay rates were determined
from the observed numbers of pi-'s and pi0's as Gamma_pi-/Gamma_tot = 0.270 +/-
0.024 and Gamma_pi0/Gamma_tot = 0.564 +/- 0.036, respectively, and the values
of the proton- and neutron-stimulated decay rates were extracted as
Gamma_p/Gamma_tot = 0.169 +/- 0.019 and Gamma_n/Gamma_tot <= 0.032 (95% CL),
respectively. The effects of final-state interactions and possible 3-body
Lambda N N decay contributions were studied in the context of a simple model of
nucleon-stimulated decay. Nucleon-nucleon coincidence events were observed and
were used in the determination of the non-mesonic branching fractions. The
implications of the results of this analysis were considered for the empirical
Delta I = 1/2 rule and the decay rates of the 4H-Lambda hypernucleus.Comment: 15 pages, 11 figures, published in PRC, revised content to match
published versio
Perturbation theory for optimizing the exit irradiation in a multi zone candu reactor
Formulation of the problem -- The optimization procedure -- The linearization process -- Generalized perturbation theory -- Explicit perturbation method -- Numerical results
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Cyberbullying and Its Relationship to Current Symptoms and History of Early Life Trauma: A Study of Adolescents in an Acute Inpatient Psychiatric Unit
Cyberbullying has received wide media attention and appears to be linked to frequent adverse consequences, with multiple suicides reported. This study examined the prevalence of cyberbullying among adolescent psychiatric inpatients and related it to social media usage, current levels of symptoms, and histories of adverse early life experience.
Data on the prevalence of social media utilization and cyberbullying victimization were collected from adolescent psychiatric inpatients aged 13 to 17 years from September 2016 to April 2017. Fifty adolescent psychiatric inpatients completed 2 surveys assessing childhood trauma (the Trauma Symptom Checklist for Children and the Childhood Trauma Questionnaire) and the Cyberbullying Questionnaire.
Twenty percent of participants (10/50) had been victimized by cyberbullying. Access to and engagement in social media or Internet-based communication was extremely common, with most participants engaging on a daily basis or more frequently in at least 1 social media activity. Those who had been bullied endorsed significantly higher scores on posttraumatic stress disorder (PTSD), depression, anger, and fantasy dissociation scales than those who were not bullied (all P values < .05). Subjects who reported having been victims of cyberbullying endorsed significantly higher levels of lifetime emotional abuse on the Childhood Trauma Questionnaire than those who were not bullied (P = .013); however, they did not report a significantly higher level of the other types of trauma (physical abuse, sexual abuse, emotional neglect, or physical neglect). More bullied than nonbullied subjects had clinically and statisticallysignificant elevations in hyperresponse, PTSD, and depression scale scores (P < .05).
Being cyberbullied was associated with greater psychiatric symptom severity. Further, histories of emotional abuse were correlated with recent cyberbullying. These data suggest that individuals with histories of childhood trauma also seem vulnerable to continued adverse experiences during adolescence
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