26 research outputs found
Free particle scattering off two oscillating disks
We investigate the two-dimensional classical dynamics of the scattering of
point particles by two periodically oscillating disks. The dynamics exhibits
regular and chaotic scattering properties, as a function of the initial
conditions and parameter values of the system. The energy is not conserved
since the particles can gain and loose energy from the collisions with the
disks. We find that for incident particles whose velocity is on the order of
the oscillating disk velocity, the energy of the exiting particles displays
non-monotonic gaps of allowed energies, and the distribution of exiting
particle velocities shows significant fluctuations in the low energy regime. We
also considered the case when the initial velocity distribution is Gaussian,
and found that for high energies the exit velocity distribution is Gaussian
with the same mean and variance. When the initial particle velocities are in
the irregular regime the exit velocity distribution is Gaussian but with a
smaller mean and variance. The latter result can be understood as an example of
stochastic cooling. In the intermediate regime the exit velocity distribution
differs significantly from Gaussian. A comparison of the results presented in
this paper to previous chaotic static scattering problems is also discussed.Comment: 9 doble sided pages 13 Postscript figures, REVTEX style. To appear in
Phys. Rev.
Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020
We show the distribution of SARS-CoV-2 genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three available genomic nomenclature systems for SARS-CoV-2 to all sequence data from the WHO European Region available during the COVID-19 pandemic until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation. We provide a comparison of the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2.Peer reviewe
Surviving Sepsis Campaign: International guidelines for management of severe sepsis and septic shock: 2008
SCOPUS: ar.jinfo:eu-repo/semantics/publishe
A comparison of the CAPS-5 and PCL-5 to assess PTSD in military and veteran treatment-seeking samples
Background: This study was an examination of the puzzling finding that people assessed for symptoms of posttraumatic stress disorder (PTSD) consistently score higher on the self-report PTSD Checklist for DSM-5 (PCL-5) than the Clinician-Administered PTSD Scale for DSM-5 (CAPS-5). Both scales purportedly assess PTSD severity with the same number of items, scaling, and scoring range, but differences in scores between measures make outcomes difficult to decipher. Objective: The purpose of this study was to examine several possible psychometric reasons for the discrepancy in scores between interview and self-report. Method: Data were combined from four clinical trials to examine the baseline and posttreatment assessments of treatment-seeking active duty military personnel and veterans. Results: As in previous studies, total scores were higher on the PCL-5 compared to the CAPS-5 at baseline and posttreatment. At baseline, PCL-5 scores were higher on all 20 items, with small to large differences in effect size. At posttreatment, only three items were not significantly different. Distributions of item responses and wording of scale anchors and items were examined as possible explanations of the difference between measures. Participants were more likely to use the full range of responses on the PCL-5 compared to interviewers. Conclusions: Suggestions for improving the congruence between these two scales are discussed. Administration of interviews by trained assessors can be resource intensive, so it is important that those assessing PTSD severity are afforded confidence in the equivalence of their assessment of PTSD regardless of the assessment method used