3,099 research outputs found

    A new rhynchocephalian from the late jurassic of Germany with a dentition that is unique amongst tetrapods.

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    Rhynchocephalians, the sister group of squamates (lizards and snakes), are only represented by the single genus Sphenodon today. This taxon is often considered to represent a very conservative lineage. However, rhynchocephalians were common during the late Triassic to latest Jurassic periods, but rapidly declined afterwards, which is generally attributed to their supposedly adaptive inferiority to squamates and/or Mesozoic mammals, which radiated at that time. New finds of Mesozoic rhynchocephalians can thus provide important new information on the evolutionary history of the group. A new fossil relative of Sphenodon from the latest Jurassic of southern Germany, Oenosaurus muehlheimensis gen. et sp. nov., presents a dentition that is unique amongst tetrapods. The dentition of this taxon consists of massive, continuously growing tooth plates, probably indicating a crushing dentition, thus representing a previously unknown trophic adaptation in rhynchocephalians. The evolution of the extraordinary dentition of Oenosaurus from the already highly specialized Zahnanlage generally present in derived rhynchocephalians demonstrates an unexpected evolutionary plasticity of these animals. Together with other lines of evidence, this seriously casts doubts on the assumption that rhynchocephalians are a conservative and adaptively inferior lineage. Furthermore, the new taxon underlines the high morphological and ecological diversity of rhynchocephalians in the latest Jurassic of Europe, just before the decline of this lineage on this continent. Thus, selection pressure by radiating squamates or Mesozoic mammals alone might not be sufficient to explain the demise of the clade in the Late Mesozoic, and climate change in the course of the fragmentation of the supercontinent of Pangaea might have played a major role

    Leaf economics fundamentals explained by optimality principles

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    The life span of leaves increases with their mass per unit area (LMA). It is unclear why. Here, we show that this empirical generalization (the foundation of the worldwide leaf economics spectrum) is a consequence of natural selection, maximizing average net carbon gain over the leaf life cycle. Analyzing two large leaf trait datasets, we show that evergreen and deciduous species with diverse construction costs (assumed proportional to LMA) are selected by light, temperature, and growing-season length in different, but predictable, ways. We quantitatively explain the observed divergent latitudinal trends in evergreen and deciduous LMA and show how local distributions of LMA arise by selection under different environmental conditions acting on the species pool. These results illustrate how optimality principles can underpin a new theory for plant geography and terrestrial carbon dynamics

    A Collaborative Approach to Eliminating Street Drug Markets through Focused Deterrence

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    This report presents the evaluation process and findings from the grant, A Collaborative Approach to Eliminating Street Drug Markets through Focused Deterrence. This action research was conducted by a team of researchers from The University of North Carolina at Greensboro‘s Center for Youth, Family, and Community Partnerships, the University of Notre Dame, and the Winston-Salem State University Center for Community Safety from January 2007 through December 2008

    A Street-Drug Elimination Initiative: The Law Enforcement Perspective

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    Purpose– The purpose of this study is to elucidate the elements, developmental stages, and operational steps of an open-air drug market intervention employed in two North Carolina communities in an effort to produce a model that can be duplicated by other law enforcement agencies. Design/methodology/approach– A systematic and practitioner-informed analysis of the steps and stages of the initiative is presented here. Law enforcement partners at the command and operational levels collectively contributed their voices to the synthesis of this model. Through purposive sampling, 13 key law enforcement stakeholders from the two police departments in North Carolina participated in semi-structured interviews conducted by a member of the research team. The interviews were transcribed and analyzed to extract participants' perceptions and recommendations regarding the intervention. Findings– Based on analyses of the interviews, the street-drug elimination strategy has been synthesized into several major steps. This paper elucidates the elements, developmental stages, and operational steps of the intervention. Research limitations/implications– This paper underscores important ingredients of the intervention and presents a model for other police departments to implement. Further examination of the strategy is necessary including research on improving the intervention, clarifying the factors that moderate the strategy's effectiveness, explicating the roles and perceptions of non-law enforcement partners and examining the continued impact of the initiative. Originality/value– The paper illustrates that this intervention has shown promise in reducing drug and violent crime associated with open-air drug markets and the research is of value to other police agencies that desire to implement this intervention

    Con amore : exploring how Italian school leaders and teachers accommodate immigrant students

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    In this study, I explored the perception of school leaders and teachers in a rural middle school in Southern Italy. For my conceptual framework, I pulled on three bodies of scholarship: intercultural education, the overall importance of school leaders, and teachers’ attitudes towards immigrant students. I conducted a basic qualitative study using interviews, documents, and field notes as part of my data collection. I was interested in how school leaders and teachers attended to the increase of immigrant students in Italy. This study aimed at answering two significant questions. First, how did school leaders attend to the increase in immigrant students in a rural middle school in Southern Italy? The second question focused on the perceptions of Italian teachers in a rural middle school in Southern Italy on how they supported immigrant students. My findings highlighted how school leaders and teachers attempted to bring an inclusive approach within their middle school. They created an inclusion project as part of the schools’ vision, which reflected intercultural education practices. In my findings, I displayed several components that positively contributed to immigrant students’ overall experience. I also highlighted factors that hindered the school leaders' and teachers’ vision for inclusion. This work contributes to the limited research on immigrant students in Southern Italy

    Evaluation of the efficacy and safety of text messages targeting adherence to cardiovascular medications in secondary prevention: the txt2heart Colombia randomised controlled trial (Preprint)

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    Background: Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of mortality in the world. Prevalence is estimated at around 100 million patients worldwide. There is evidence that antiplatelet agents and antihypertensive medication reduce the risk of new vascular events in this population, but treatment adherence is very low. Objective: We developed an intervention based on behavioral modification techniques delivered via mobile short message services (SMS) to increase the adherence to pharmacologic treatment on patients with prior history of ASCVD. Methods: We conducted a randomized controlled clinical trial for patients with a prior diagnosis of cardiovascular event such as acute myocardial infarction, unstable angina, cerebrovascular disease or peripheral artery disease in one centre in Colombia. Patients randomized to the intervention arm were assigned to receive SMS daily for the first 4 weeks, five SMS on week 5: three SMS per week from week 6, and one SMS from 8th week until 52nd week. Patients in the control arm received a monthly SMS reminding them of the next study appointment, requesting information about changes in phone number, thanking them for participating in the study and reminding them of the importance of the study. Primary endpoint was change in Low Density Lipoprotein-Cholesterol (LDL-C) and the secondary endpoints were change in thromboxane B2 levels, heart rate, systolic and diastolic blood pressure. Medication adherence was measured with the Medication Adherence Report Scale (MARS 5), mortality and new cardiac hospitalization were assessed at one year end point. A logistic regression analysis and bivariate testing was performed. Results: Nine hundred and thirty patients were randomized, 805 (87%) completed follow up, and were analyzed for the primary endpoint. There was no difference between arms in change of LDL-C at 12 months (P=.41). or for any of the secondary outcomes. No adverse events were reported. Conclusions: In our study we did not find evidence that a behavior modification intervention delivered by SMS improved LDL-C, blood pressure levels or adherence at 12 months. More research is needed to evaluate whether different SMS strategies including personalized messages and with different timing are effective; future studies should include mixed methods to understand better why, for whom and in which context (e.g. health system, social environment) SMS interventions work (or not) to improve adherence in patients with ASCVD. Clinical Trial: Clinicaltrial.gov NCT03098186. Date of registration: March 31st 201

    HUWE1 E3 ligase promotes PINK1/PARKINindependent mitophagy by regulating AMBRA1 activation via IKKa

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    The selective removal of undesired or damaged mitochondria by autophagy, known as mitophagy, is crucial for cellular homoeostasis, and prevents tumour diffusion, neurodegeneration and ageing. The pro-autophagic molecule AMBRA1 (autophagy/beclin-1 regulator-1) has been defined as a novel regulator of mitophagy in both PINK1/PARKIN-dependent and -independent systems. Here, we identified the E3 ubiquitin ligase HUWE1 as a key inducing factor in AMBRA1-mediated mitophagy, a process that takes place independently of the main mitophagy receptors. Furthermore, we show that mitophagy function of AMBRA1 is post-translationally controlled, upon HUWE1 activity, by a positive phosphorylation on its serine 1014. This modification is mediated by the IKKα kinase and induces structural changes in AMBRA1, thus promoting its interaction with LC3/GABARAP (mATG8) proteins and its mitophagic activity. Altogether, these results demonstrate that AMBRA1 regulates mitophagy through a novel pathway, in which HUWE1 and IKKα are key factors, shedding new lights on the regulation of mitochondrial quality control and homoeostasis in mammalian cells
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