Thermodynamic Limit for Mean-Field Spin Models

If the Boltzmann-Gibbs state $\omega_N$ of a mean-field $N$-particle system with Hamiltonian $H_N$ verifies the condition $$\omega_N(H_N) \ge \omega_N(H_{N_1}+H_{N_2})$$ for every decomposition $N_1+N_2=N$, then its free energy density increases with $N$. We prove such a condition for a wide class of spin models which includes the Curie-Weiss model, its p-spin generalizations (for both even and odd p), its random field version and also the finite pattern Hopfield model. For all these cases the existence of the thermodynamic limit by subadditivity and boundedness follows.Comment: 15 pages, few improvements. To appear in MPE

Mechanisms producing fissionlike binary fragments in heavy collisions

The mixing of the quasifission component to the fissionlike cross section causes ambiguity in the quantitative estimation of the complete fusion cross section from the observed angular and mass distributions of the binary products. We show that the partial cross section of quasifission component of binary fragments covers the whole range of the angular momentum values leading to capture. The calculated angular momentum distributions for the compound nucleus and dinuclear system going to quasifission may overlap: competition between complete fusion and quasifission takes place at all values of initial orbital angular momentum. Quasifission components formed at large angular momentum of the dinuclear system can show isotropic angular distribution and their mass distribution can be in mass symmetric region similar to the characteristics of fusion-fission components. As result the unintentional inclusion of the quasifission contribution into the fusion-fission fragment yields can lead to overestimation of the probability of the compound nucleus formation.Comment: 15 pages, 6 figures, International Conference on Nuclear Reactions on Nucleons and Nuclei, Messina, Italy, October 5-9, 200

Validation of a Screening Tool for Pediatric Obstructive Sleep Apnea: A Pilot Study

Purpose: The purpose of this study was to evaluate the Pediatric-Modified-STOP-Bang (PM-STOP-Bang) as a screening tool to assess sleep related breathing disorders (SRBD) within a pediatric population. The specific aims of this study were: 1) compare the PM-STOP-Bang scores with those from the validated Pediatric Sleep Questionnaire (PSQ), 2) determine the ability of the PM-STOP-Bang and the PSQ screening tools to accurately detect children of high risk for SRBD from a one-night home sleep apnea test (HSAT). Methods: Orthodontic patients were screened using the PM-STOP-Bang at VCU Graduate Clinic. Patients (n=10) who were recruited and enrolled. Five were determined to be at high risk based on PM-STOP Bang score. After enrollment, a guardian completed the PSQ, the Pediatric Symptom checklist (PSC), and the child completed a one-night HSAT. Five age-matched controls were enrolled. Results: Scores of PM-STOP-Bang compared to PSQ related to a sensitivity for the PM-STOP-Bang of 67% (95% CI: 29-100%) and a specificity of 75% (95% CI: 33-100%). Comparing the PM-STOP-Bang to the HSAT results, the PM-STOP-Bang had a sensitivity of 100% (95% CI: 100%, 100%) and a specificity of 71% (95% CI: 38%, 100%). The PSQ sensitivity was 67% (95% CI: 13%, 100%) and specificity 43% (95% CI: 6%, 80%). Conclusions: The PM-STOP-Bang achieved a greater sensitivity and specificity than the PSQ in identifying children at high risk for obstructive sleep apnea when cases were confirmed with the HSAT. A future study with a larger sample size is needed to validate the PM-STOP-Bang

EMERGENCY MANAGEMENT—A WICKED SOLUTION?

Emergency management agencies nationally are increasingly involved in the management of wicked problems in their communities. This thesis explores how the government can use emergency management agencies in response to wicked problems. To answer this question, this thesis takes a multi-step approach that compares the collaborative approach to wicked problem–solving and the ways in which emergency management fosters collaboration for disaster response. The comparison shows that emergency management’s tools can support collaborative responses to wicked problems, but capacity problems in the field of emergency management hinder involvement. This thesis’s conclusion recognizes that concerns about emergency management’s existing workload, underfunded and limited budgets, and the potential negative impacts of a new mission balanced with existing missions are valid. Ultimately, this thesis recognizes four possible outcomes for decision-makers. If emergency management is assigned the wicked problem space without additional resources, both mission areas will falter. If properly resourced, emergency management can adequately address wicked problems and their current workload. The third outcome leaves emergency management outside of the wicked problem mission, while the fourth outcome is to take what works from emergency management and apply it across the government. Ultimately, each outcome alters emergency management’s ability to respond to major disasters.Civilian, Philadelphia Office of Emergency ManagementApproved for public release. Distribution is unlimited

A phase-separation perspective on dynamic heterogeneities in glass-forming liquids

We study dynamic heterogeneities in a model glass-former whose overlap with a reference configuration is constrained to a fixed value. The system phase-separates into regions of small and large overlap, so that dynamical correlations remain strong even for asymptotic times. We calculate an appropriate thermodynamic potential and find evidence of a Maxwell's construction consistent with a spinodal decomposition of two phases. Our results suggest that dynamic heterogeneities are the expression of an ephemeral phase-separating regime ruled by a finite surface tension