Action minimizing fronts in general FPU-type chains

We study atomic chains with nonlinear nearest neighbour interactions and prove the existence of fronts (heteroclinic travelling waves with constant asymptotic states). Generalizing recent results of Herrmann and Rademacher we allow for non-convex interaction potentials and find fronts with non-monotone profile. These fronts minimize an action integral and can only exists if the asymptotic states fulfil the macroscopic constraints and if the interaction potential satisfies a geometric graph condition. Finally, we illustrate our findings by numerical simulations.Comment: 19 pages, several figure

Impacts of Land Abandonment on Vegetation: Successional Pathways in European Habitats

Changes in traditional agricultural systems in Europe in recent decades have led to widespread abandonment and colonization of various habitats by shrubs and trees. We combined several vegetation databases to test whether patterns of changes in plant diversity after land abandonment in different habitats followed similar pathways. The impacts of land abandonment and subsequent woody colonization on vegetation composition and plant traits were studied in five semi-natural open habitats and two arable habitats in six regions of Europe. For each habitat, vegetation surveys were carried out in different stages of succession using either permanent or non-permanent plots. Consecutive stages of succession were defined on a physiognomic basis from initial open stages to late woody stages. Changes in vegetation composition, species richness, numbers of species on Red Lists, plant strategy types, Ellenberg indicator values of the vegetation, Grime CSR strategy types and seven ecological traits were assessed for each stage of the successional pathway. Abandonment of agro-pastoral land-use and subsequent woody colonization were associated with changes in floristic composition. Plant richness varied according to the different habitats and stages of succession, but semi-natural habitats differed from arable fields in several ecological traits and vegetation responses. Nevertheless, succession occurred along broadly predictable pathways. Vegetation in abandoned arable fields was characterized by a decreasing importance of R-strategists, annuals, seed plants with overwintering green leaves, insect-pollinated plants with hemi-rosette morphology and plants thriving in nutrient-rich conditions, but an increase in species considered as endangered according to the Red Lists. Conversely, changes in plant traits with succession within the initially-open semi-natural habitats showed an increase in plants thriving in nutrient-rich conditions, stress-tolerant plants and plants with sexual and vegetative reproduction, but a sharp decrease in protected species. In conclusion, our study showed a set of similarities in responses of the vegetation in plant traits after land abandonment, but we also highlighted differences between arable fields and semi-natural habitats, emphasizing the importance of land-use legacy

Factors Associated with Opioid Overdose after an Initial Opioid Prescription

Importance: The opioid epidemic continues to be a public health crisis in the US. Objective: To assess the patient factors and early time-varying prescription-related factors associated with opioid-related fatal or nonfatal overdose. Design, Setting, and Participants: This cohort study evaluated opioid-naive adult patients in Oregon using data from the Oregon Comprehensive Opioid Risk Registry, which links all payer claims data to other health data sets in the state of Oregon. The observational, population-based sample filled a first (index) opioid prescription in 2015 and was followed up until December 31, 2018. Data analyses were performed from March 1, 2020, to June 15, 2021. Exposures: Overdose after the index opioid prescription. Main Outcomes and Measures: The outcome was an overdose event. The sample was followed up to identify fatal or nonfatal opioid overdoses. Patient and prescription characteristics were identified. Prescription characteristics in the first 6 months after the index prescription were modeled as cumulative, time-dependent measures that were updated monthly through the sixth month of follow-up. A time-dependent Cox proportional hazards regression model was used to assess patient and prescription characteristics that were associated with an increased risk for overdose events. Results: The cohort comprised 236921 patients (133 839 women [56.5%]), of whom 667 (0.3%) experienced opioid overdose. Risk of overdose was highest among individuals 75 years or older (adjusted hazard ratio [aHR], 3.22; 95% CI, 1.94-5.36) compared with those aged 35 to 44 years; men (aHR, 1.29; 95% CI, 1.10-1.51); those who were dually eligible for Medicaid and Medicare Advantage (aHR, 4.37; 95% CI, 3.09-6.18), had Medicaid (aHR, 3.77; 95% CI, 2.97-4.80), or had Medicare Advantage (aHR, 2.18; 95% CI, 1.44-3.31) compared with those with commercial insurance; those with comorbid substance use disorder (aHR, 2.74; 95% CI, 2.15-3.50), with depression (aHR, 1.26; 95% CI, 1.03-1.55), or with 1 to 2 comorbidities (aHR, 1.32; 95% CI, 1.08-1.62) or 3 or more comorbidities (aHR, 1.90; 95% CI, 1.42-2.53) compared with none. Patients were at an increased overdose risk if they filled oxycodone (aHR, 1.70; 95% CI, 1.04-2.77) or tramadol (aHR, 2.80; 95% CI, 1.34-5.84) compared with codeine; used benzodiazepines (aHR, 1.06; 95% CI, 1.01-1.11); used concurrent opioids and benzodiazepines (aHR, 2.11; 95% CI, 1.70-2.62); or filled opioids from 3 or more pharmacies over 6 months (aHR, 1.38; 95% CI, 1.09-1.75). Conclusions and Relevance: This cohort study used a comprehensive data set to identify patient and prescription-related risk factors that were associated with opioid overdose. These findings may guide opioid counseling and monitoring, the development of clinical decision-making tools, and opioid prevention and treatment resources for individuals who are at greatest risk for opioid overdose

How should we measure psychological resilience in sport performers?

Psychological resilience is important in sport because athletes must constantly withstand a wide range of pressures to attain and sustain high performance. To advance psychologists’ understanding of this area, there exists an urgent need to develop a sport-specific measure of resilience. The purpose of this paper is to review psychometric issues in resilience research and to discuss the implications for sport psychology. Drawing on the wider general psychology literature to inform the discussion, the narrative is divided into three main sections relating to resilience and its assessment: adversity, positive adaptation, and protective factors. The first section reviews the different ways that adversity has been measured and considers the potential problems of using items with varying degrees of controllability and risk. The second section discusses the different approaches to assessing positive adaptation and examines the issue of circularity pervasive in resilience research. The final section explores the various issues related to the assessment of protective factors drawing directly from current measures of resilience in other psychology sub-disciplines. The commentary concludes with key recommendations for sport psychology researchers seeking to develop a measure of psychological resilience in athletes

Radial Velocity Studies of Close Binary Stars. XI

Radial-velocity measurements and sine-curve fits to the orbital radial velocity variations are presented for ten close binary systems: DU Boo, ET Boo, TX Cnc, V1073 Cyg, HL Dra, AK Her, VW LMi, V566 Oph, TV UMi and AG Vir. By this contribution, the DDO program has reached the point of 100 published radial velocity orbits. The radial velocities have been determined using an improved fitting technique which uses rotational profiles to approximate individual peaks in broadening functions. Three systems, ET Boo, VW LMi and TV UMi, were found to be quadruple while AG Vir appears to be a spectroscopic triple. ET Boo, a member of a close visual binary with $P_{vis} = 113$ years, was previously known to be a multiple system, but we show that the second component is actually a close, non-eclipsing binary. The new observations enabled us to determine the spectroscopic orbits of the companion, non-eclipsing pairs in ET Boo and VW LMi. The particularly interesting case is VW LMi, where the period of the mutual revolution of the two spectroscopic binaries is only 355 days. While most of the studied eclipsing pairs are contact binaries, ET Boo is composed of two double-lined detached binaries and HL Dra is single-lined detached or semi-detached system. Five systems of this group were observed spectroscopically before: TX Cnc, V1073 Cyg, AK Her (as a single-lined binary), V566 Oph, AG Vir, but our new data are of much higher quality than the previous studies.Comment: Accepted by AJ, August 2006, 10 figures, 3 table

Evidence of a Massive Black Hole Companion in the Massive Eclipsing Binary V Puppis

Up to now, most stellar-mass black holes were discovered in X-ray emitting binaries, in which the black holes are formed through a common-envelope evolu tion. Here we give evidence for the presence of a massive black hole candidate as a tertiary companion in the massive eclipsing binary V Puppis. We found that the orbital period of this short-period binary (P=1.45 days) shows a periodic variation while it undergoes a long-term increase. The cyclic period oscillation can be interpreted by the light-travel time effect via the presence of a third body with a mass no less than 10.4 solar mass. However, no spectral lines of the third body were discovered indicating that it is a massive black hole candidate. The black hole candidate may correspond to the weak X-ray source close to V Puppis discovered by Uhuru, Copernicus, and ROSAT satellites produced by accreting materials from the massive binary via stellar wind. The circumstellar matter with many heavy elements around this binary may be formed by the supernova explosion of the progenitor of the massive black hole. All of the observations suggest that a massive black hole is orbiting the massive close binary V Puppis with a period of 5.47 years. Meanwhile, we found the central close binary is undergoing slow mass transfer from the secondary to the primary star on a nuclear time scale of the secondary component, revealing that the system has passed through a rapid mass-transfer stage.Comment: Accepted for publication in ApJ