The Hall instability of weakly ionized, radially stratified, rotating disks

Cool weakly ionized gaseous rotating disk, are considered by many models as the origin of the evolution of protoplanetary clouds. Instabilities against perturbations in such disks play an important role in the theory of the formation of stars and planets. Thus, a hierarchy of successive fragmentations into smaller and smaller pieces as a part of the Kant-Laplace theory of formation of the planetary system remains valid also for contemporary cosmogony. Traditionally, axisymmetric magnetohydrodynamic (MHD), and recently Hall-MHD instabilities have been thoroughly studied as providers of an efficient mechanism for radial transfer of angular momentum, and of density radial stratification. In the current work, the Hall instability against nonaxisymmetric perturbations in compressible rotating fluids in external magnetic field is proposed as a viable mechanism for the azimuthal fragmentation of the protoplanetary disk and thus perhaps initiating the road to planet formation. The Hall instability is excited due to the combined effect of the radial stratification of the disk and the Hall electric field, and its growth rate is of the order of the rotation period.Comment: 15 pages, 2 figure

Boundedness properties of fermionic operators

The fermionic second quantization operator $d\Gamma(B)$ is shown to be bounded by a power $N^{s/2}$ of the number operator $N$ given that the operator $B$ belongs to the $r$-th von Neumann-Schatten class, $s=2(r-1)/r$. Conversely, number operator estimates for $d\Gamma(B)$ imply von Neumann-Schatten conditions on $B$. Quadratic creation and annihilation operators are treated as well.Comment: 15 page

Symptoms predicting psychosocial impairment in bulimia nervosa

Purpose The current study aimed to determine which particular eating disorder (ED) symptoms and related features, such as BMI and psychological distress, uniquely predict impairment in bulimia nervosa (BN). Methods Two hundred and twenty-two adults with BN completed questionnaires assessing ED symptoms, general psychological distress, and psychosocial impairment. Regression analyses were used to determine predictors which account for variance in impairment. Results Four variables emerged as significant predictors of psychosocial impairment: concerns with eating; concerns with weight and shape; dietary restraint; and general psychological distress. Conclusions Findings support previous work highlighting the importance of weight and shape concerns in determining ED-related impairment. Other ED symptoms, notably dietary restraint and concerns with eating, were also significant predictors as was psychological distress. Results suggest that cognitive aspects of EDs, in addition to psychological distress, may be more important determinants of impairment than behavioural symptoms, such as binge eating or purging

Further development of the 12-item EDEQS: identifying a cut-off for screening purposes

Background: The Eating Disorder Examination – Questionnaire Short (EDE-QS) was developed as a 12-item versionof the Eating Disorder Examination Questionnaire (EDE-Q) with a 4-point response scale that assesses eatingdisorder (ED) symptoms over the preceding 7 days. It has demonstrated good psychometric properties at initialtesting. The purpose of this brief report is to determine a threshold score that could be used in screening forprobable ED cases in community settings.Methods: Data collected from Gideon et al. (2016) were re-analyzed. In their study, 559 participants (80.86% female;9.66% self-reported ED diagnosis) completed the EDE-Q, EDE-QS, SCOFF, and Clinical Impairment Assessment (CIA).Discriminatory power was compared between ED instruments using receiver operating characteristic (ROC) curveanalyses.Results: A score of 15 emerged as the threshold that ensured the best trade-off between sensitivity (.83) andspecificity (.85), and good positive predictive value (.37) for the EDE-QS, with discriminatory power comparable toother ED instruments.Conclusion: The EDE-QS appears to be an instrument with good discriminatory power that could be used for EDscreening purposes

Factors shaping the lived experience of resettlement for former refugees in regional Australia

Refugees experience traumatic life events with impacts amplified in regional and rural areasdue to barriers accessing services. This study examined the factors influencing the lived experienceof resettlement for former refugees in regional Launceston, Australia, including environmental,social, and health-related factors. Qualitative interviews and focus groups were conducted withadult and youth community members from Burma, Bhutan, Sierra Leone, Afghanistan, Iran,and Sudan, and essential service providers (n = 31). Thematic analysis revealed four factorsas primarily influencing resettlement: English language proficiency; employment, education andhousing environments and opportunities; health status and service access; and broader socialfactors and experiences. Participants suggested strategies to overcome barriers associated with thesefactors and improve overall quality of life throughout resettlement. These included flexible Englishlanguage program delivery and employment support, including industry-specific language courses;the provision of interpreters; community events fostering cultural sharing, inclusivity and promotingwell-being; and routine inclusion of nondiscriminatory, culturally sensitive, trauma-informed practicesthroughout a former refugee’s environment, including within education, employment, housing andservice settings

Kinetic approaches to particle acceleration at cosmic ray modified shocks

Kinetic approaches provide an effective description of the process of particle acceleration at shock fronts and allow to take into account the dynamical reaction of the accelerated particles as well as the amplification of the turbulent magnetic field as due to streaming instability. The latter does in turn affect the maximum achievable momentum and thereby the acceleration process itself, in a chain of causality which is typical of non-linear systems. Here we provide a technical description of two of these kinetic approaches and show that they basically lead to the same conclusions. In particular we discuss the effects of shock modification on the spectral shape of the accelerated particles, on the maximum momentum, on the thermodynamic properties of the background fluid and on the escaping and advected fluxes of accelerated particles.Comment: 22 pages, 7 figures, accepted for publication in MNRA

Likelihood Geometry

We study the critical points of monomial functions over an algebraic subset of the probability simplex. The number of critical points on the Zariski closure is a topological invariant of that embedded projective variety, known as its maximum likelihood degree. We present an introduction to this theory and its statistical motivations. Many favorite objects from combinatorial algebraic geometry are featured: toric varieties, A-discriminants, hyperplane arrangements, Grassmannians, and determinantal varieties. Several new results are included, especially on the likelihood correspondence and its bidegree. These notes were written for the second author's lectures at the CIME-CIRM summer course on Combinatorial Algebraic Geometry at Levico Terme in June 2013.Comment: 45 pages; minor changes and addition

Eating Disorder Behaviors Are Increasing: Findings from Two Sequential Community Surveys in South Australia

Background: evidence for an increase in the prevalence of eating disorders is inconsistent. Our aim was to determine change in the population point prevalence of eating disorder behaviors over a 10-year period. \ud \ud Methodology/Principal Findings: eating disorder behaviors were assessed in consecutive general population surveys of men and women conducted in 1995 (n = 3001, 72% respondents) and 2005 (n = 3047, 63.1% respondents). Participants were randomly sampled from households in rural and metropolitan South Australia. There was a significant (all p,0.01) and over two-fold increase in the prevalence of binge eating, purging (self-induced vomiting and/or laxative or diuretic misuse) and strict dieting or fasting for weight or shape control among both genders. The most common diagnosis in 2005 was either binge eating disorder or other ‘‘eating\ud disorders not otherwise specified’’ (EDNOS; n = 119, 4.2%). \ud \ud Conclusions/Significance: in this population sample the point prevalence of eating disorder behaviors increased over the past decade. Cases of anorexia nervosa and bulimia nervosa, as currently defined, remain uncommon