799 research outputs found
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Refining genetic boundaries for Agassiz’s desert tortoise (Gopherus agassizii) in the western Sonoran Desert: the influence of the Coachella Valley on gene flow among populations in southern California
Understanding the influence of geographic features on the evolutionary history and population structure of a species can assist wildlife managers in delimiting genetic units (GUs) for conservation and management. Landscape features including mountains, low elevation depressions, and even roads can influence connectivity and gene flow among Agassiz’s desert tortoise (Gopherus agassizii) populations. Substantial changes in the landscape of the American Southwest occurred during the last six million years (including the formation of the Gulf of California and the lower Colorado River), which shaped the distribution and genetic structuring of tortoise populations. The area northwest of the Gulf of California is occupied by the Salton Trough, including the Coachella Valley at its northern end. Much of this area is below sea level and unsuitable as tortoise habitat, thus forming a potential barrier for gene flow. We assessed genetic relationships among three tortoise populations separated by the Coachella Valley. Two adjacent populations were on the east side of the valley in the foothills of the Cottonwood and Orocopia mountains separated by Interstate 10. The third population, Mesa, was located about 87 km away in the foothills of the San Bernardino Mountains at the far northwestern tip of the valley. The Cottonwood and Orocopia localities showed genetic affiliation with the adjacent Colorado Desert GU immediately to the east, and the Mesa population exhibited affiliation with both the Southern Mojave and Colorado Desert GUs, despite having a greater geographic distance (0.5x–1.5x greater) to the Colorado Desert GU. The genetic affiliation with the Colorado Desert GU suggests that the boundary for that GU needs to be substantially extended to the west to include the desert tortoise populations around the Coachella Valley. Their inclusion in the Colorado Desert GU may benefit these often overlooked populations when recovery actions are considered
A longitudinal study of perceived health during pregnancy: antecedents and outcomes
Perceived health was studied longitudinally in a sample of 364 nulliparous women. Psychosocial, contextual, and biomedical factors were taken into account to predict medically relevant versus benign symptoms which were then used to predict perceived health over time. The results of structural equation modeling showed that pregnancy adjustment and medically relevant symptoms which were affected by social support, perceived stress, and negative affect predicted later perceived health. The outcomes of perceived health were examined during the third trimester in terms of medical care utilization and emergency room visits. Perceived health solely accounted for medical care utilization, while emergency room visits were accounted by medical care utilization and perceived stress
Family systemic psychosocial support for at-risk adolescents in Lebanon: study protocol for a multi-site randomised controlled trial
Background: Adolescents growing up in communities characterised by adversity face multiple risk factors for poor mental health and wellbeing. There is currently a scarcity of research on effective approaches for preventing and treating psychological distress in this population, particularly in humanitarian settings. The powerful impact of the home environment and family support is well known; however, approaches targeting the family are seldom developed or evaluated in such settings. We developed a brief family systemic psychosocial support intervention to be delivered through existing child protection systems with non-specialist facilitators. This paper outlines the study protocol for a randomised controlled trial of the intervention in Lebanon.Methods: We will conduct a single-blind hybrid effectiveness-implementation multi-site RCT comparing the locally developed systemic family intervention to a waitlist control group for families residing in vulnerable regions in North Lebanon and Beqaa governorates (including families of Syrian, Palestinian, and Lebanese backgrounds). Outcomes on a range of family, adolescent, and caregiver measures will be assessed at baseline (T0) and post-intervention (T1), and at a 3-month follow-up for the treatment arm (T2). Families will be eligible for the trial if they are identified by implementing organisations as being medium-to-high risk for child protection concerns and have one or more adolescent aged 12–17 who demonstrates significant psychological distress on a self-report brief screening tool. Families will be randomly assigned to a treatment or a waitlist control condition. Families in the waitlist condition will receive a group version of the programme after completion of the study, to allow us to assess feasibility, acceptability, and preliminary indications of intervention effects of this modality. The primary outcome is reduction in overall adolescent-reported psychological distress over time, with post-intervention (T1) as the primary endpoint. Secondary adolescent-reported outcomes include family functioning, psychosocial wellbeing, and emotional regulation difficulties. Secondary caregiver-reported outcomes include parenting style, family functioning, psychological distress, and emotional regulation difficulties. Discussion: This trial will provide the first assessment of the effectiveness of the family systemic psychosocial support intervention for use in Lebanon, with important implications for the use of systemic, low-cost, non-specialist interventions for this age range. Trial registration: Local registry: National Mental Health Program, Ministry of Public Health, Lebanese Republic. Registered on 19 October 2021 Lebanese Clinical Trial Registry LBCTR2021104870
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Arenavirus budding resulting from viral-protein-associated cell membrane curvature
Viral replication occurs within cells, with release (and onward infection) primarily achieved through two alternative mechanisms: lysis, in which virions emerge as the infected cell dies and bursts open; or budding, in which virions emerge gradually from a still living cell by appropriating a small part of the cell membrane. Virus budding is a poorly understood process that challenges current models of vesicle formation. Here, a plausible mechanism for arenavirus budding is presented, building on recent evidence that viral proteins embed in the inner lipid layer of the cell membrane. Experimental results confirm that viral protein is associated with increased membrane curvature, whereas a mathematical model is used to show that localized increases in curvature alone are sufficient to generate viral buds. The magnitude of the protein-induced curvature is calculated from the size of the amphipathic region hypothetically removed from the inner membrane as a result of translation, with a change in membrane stiffness estimated from observed differences in virion deformation as a result of protein depletion. Numerical results are based on experimental data and estimates for three arenaviruses, but the mechanisms described are more broadly applicable. The hypothesized mechanism is shown to be sufficient to generate spontaneous budding that matches well both qualitatively and quantitatively with experimental observations
Treatment of Cavernous Sinus Aneurysms with Flow Diversion: Results in 44 Patients
ABSTRACT BACKGROUND AND PURPOSE: Aneurysms of the cavernous segment of the ICA are difficult to treat with standard endovascular techniques, and ICA sacrifice achieves a high rate of occlusion but carries an elevated level of surgical complications and risk of de novo aneurysm formation. We report rates of occlusion and treatment-related data in 44 patients with cavernous sinus aneurysms treated with flow diversion
Changes in Russian managerial values: a test of the convergence hypothesis?
This paper considers how Russian managerial values are developing in the context of the sweeping economic, political and social changes associated with the transition of Russia to a market economy. By replicating earlier research (Holt et al., 1994; Ralston et al., 1997), it was possible to overcome the weaknesses of previous cross-sectional studies by tracking changes in Russian managers' values over time. The paper concludes that some convergence between the values of Russian and US managers can be observed, but that the form of this convergence is not uniform. In addition, the way in which Russian managers act upon these values in the context of their own national context means that considerable divergence in managerial behaviour is still evident. Implications for international human resource management are discussed
Attitudes and Performance: An Analysis of Russian Workers
This paper investigates the relationship between locus of control and performance among Russian employees, using survey data collected at 28 workplaces in 2002 in Taganrog and at 47 workplaces in 2003 in Ekaterinburg. We develop a measure that allows us to categorize the Russian employees participating in our survey as exhibiting an internal or external locus of control. We then assess the extent to which there are significant differences between “internals” and “externals” in work-related attitudes that may affect performance. In particular, we focus on (1) attitudes about outcomes associated with hard work, (2) level of job satisfaction, (3) expectation of receiving a desired reward, and (4) loyalty to and involvement with one’s organization. In each case we identify where gender and generational differences emerge. Our main objective is to determine whether Russian employees who exhibit an internal locus of control perform better than employees with an external locus of control. Our performance measures include earnings, expected promotions, and assessments of the quantity and quality of work in comparison to others at the same organization doing a similar job. Controlling for a variety of worker characteristics, we find that (1) individuals who exhibit an internal locus of control perform better, but this result is not always statistically significant; (2) even among “internals,” women earn significantly less than men and have a much lower expectation of promotion; (3) even among “internals,” experience with unemployment has a negative influence on performance.http://deepblue.lib.umich.edu/bitstream/2027.42/40144/3/wp758.pd
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