5,440 research outputs found

    Substance and non-substance addictions

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    What are we talking about when we speak of substance and nonsubstance addictions? Why is prevention important to society? What are the impacts of prevention on general health? These questions were the guidelines for structuring this paper, in which the conceptualization of prevention and prevention practices are systematically discussed. Furthermore, some emerging challenges in the development of preventive strategies are raised. The present paper starts with a theoretical debate, supported with empirical evidence and literature.info:eu-repo/semantics/publishedVersio

    Liquid Polymorphism and Density Anomaly in a Lattice Gas Model

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    We present a simple model for an associating liquid in which polymorphism and density anomaly are connected. Our model combines a two dimensional lattice gas with particles interacting through a soft core potential and orientational degrees of freedom represented through thermal \char`\"{}ice variables\char`\"{} . The competition between the directional attractive forces and the soft core potential leads to a phase diagram in which two liquid phases and a density anomaly are present. The coexistence line between the low density liquid and the high density liquid has a positive slope contradicting the surmise that the presence of a density anomaly implies that the high density liquid is more entropic than the low density liquid

    Meson-like Baryons and the Spin-Orbit Puzzle

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    I describe a special class of meson-like \Lambda_Q excited states and present evidence supporting the similarity of their spin-independent spectra to those of mesons. I then examine spin-dependent forces in these baryons, showing that predicted effects of spin-orbit forces are small for them for the same reason they are small for the analogous mesons: a fortuitous cancellation between large spin-orbit forces due to one-gluon-exchange and equally large inverted spin-orbit forces due to Thomas precession in the confining potential. In addition to eliminating the baryon spin-orbit puzzle in these states, this solution provides a new perspective on spin-orbit forces in all baryons.Comment: 24 pages, 4 figure

    Advanced structural characterization of biocompatible Ag-TiCN coatings

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    One of the main reasons for biomedical implants failure is the generation of wear debris together with microbial infection. To overcome this problem it has been proposed the use of very low wear coatings as diamond-like carbon (DLC), transitionmetal carbides (MeCx) or nitrides (MeNx) in combination with antibacterial elements such silver, gold or copper. The present work explores the potentialities of silver-containing carbon/nitride (Ag-TiCN) based coatings to be used as protective thin films for biomedical implants. Samples were prepared by DC unbalanced reactive magnetron sputtering with contents of Ag ranging from 0 to 20 at.% and Ti from 35 to 15 at.% while keeping C, N and O content constant. The coatings were fully characterized in terms of structure (XRD, Raman) and depth profiling composition by GDOES and RBS (using the nitrogen resonance at 3.70 MeV He+ ions). In particular, we have selected three samples with different Ag contents (0, 6 and 20%) and carried out and advanced surface characterization using XPS, ARXPS and HR-SEM to study the segregation of silver towards the surface. We have correlated the structure and composition of the films with their biological properties. Microbial adhesion was assessed for both bacteria (Staphylococcus epidermidis) and yeast (Candida albicans)

    Direct experimental test of scalar confinement

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    The concept of Lorentz scalar quark confinement has a long history and is still widely used despite its well-known theoretical faults. We point out here that the predictions of scalar confinement also conflict directly with experiment. We investigate the dependence of heavy-light meson mass differences on the mass of the light quark. In particular, we examine the strange and non-strange D mesons. We find that the predictions of scalar confinement are in considerable conflict with measured values.Comment: REVTeX4, 7 pages, 4 EPS figure

    Obesity-related knowledge and body mass index : a national survey in Portugal

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    © 2019 Springer Nature Switzerland AG. Part of Springer Nature.Purpose: Obesity-related knowledge predicts weight control but previous studies only comprise individuals with excessive weight and assess very specific aspects of knowledge. This study aims to evaluate several domains of obesity-related knowledge according to the body mass index (BMI) in a representative sample of Portuguese-speaking dwellers in mainland Portugal. Methods: A sample of 1624 participants aged 16–79 years was analyzed. Eighteen questions comprising eight obesity domains were asked: prevalence, physical activity, number of calories, adiposity location, causes, diagnosis, treatment and consequences; each one was dichotomized into correct/incorrect knowledge. Results: The majority of Portuguese-speaking dwellers recognized the benefits of physical activity, the risks of abdominal obesity and most consequences of excessive weight, independently of their BMI. However, knowledge gaps were identified regarding prevalence, calories and BMI diagnosis. BMI influenced specific obesity-related knowledge: participants with a normal BMI knew the BMI formula more often, identified 22 as normal BMI more frequently and had the highest proportion of correct knowledge regarding the number of calories an adult should eat; obese individuals identified natural products as not being good treatments for obesity more often. After adjusting for age, sex and educational level, obese individuals identified natural products and supplements as not being good obesity treatments more often. Conclusions: Obesity-related knowledge gaps (prevalence, calories, and diagnosis) were identified among Portuguese adults. Moreover, correct knowledge does not necessarily translate into a healthier BMI. Besides the dissemination of accurate information, public health interventions should focus on the transfer of knowledge to behaviors that will guarantee better weight management. Evidence-based medicine rankings: Level V: Opinions of respected authorities, based on descriptive studies, narrative reviews, clinical experience, or reports of expert committees.This study was supported by FEDER funds through Operational Programme Competitiveness and Internationalization and by national funding from The Portuguese Foundation for Science and Technology—FCT (Portuguese Ministry of Education and Science) within the project (HMSP-IISE/SAU-ICT/0004/2009) and within the Epidemiology Research Unit—Institute of Public Health, University of Porto (EPIUnit) (POCI-01-0145-FEDER-006862; Ref. UID/ DTP/04750/2013). Additionally, we gratefully acknowledge the FCT Investigator contract IF/01674/2015 (Susana Silva) and also a Scientifc Employment Stimulus contract CEECIND/01793/2017 (Ana Henriques). The funding source had no role in the study design, collection, analysis, or interpretation of data, writing the manuscript, or the decision to submit the manuscript for publication.info:eu-repo/semantics/publishedVersio

    Spider peptide toxin HwTx-IV engineered to bind to lipid membranes has an increased inhibitory potency at human voltage-gated sodium channel hNaV1.7

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    The human voltage-gated sodium channel sub-type 1.7 (hNaV1.7) is emerging as an attractive target for the development of potent and sub-type selective novel analgesics with increased potency and fewer side effects than existing therapeutics. HwTx-IV, a spider derived peptide toxin, inhibits hNaV1.7 with high potency and is therefore of great interest as an analgesic lead. In the current study we examined whether engineering a HwTx-IV analogue with increased ability to bind to lipid membranes would improve its inhibitory potency at hNaV1.7. This hypothesis was explored by comparing HwTx-IV and two analogues [E1PyrE]HwTx-IV (mHwTx-IV) and [E1G,E4G,F6W,Y30W]HwTx-IV (gHwTx-IV) on their membrane-binding affinity and hNaV1.7 inhibitory potency using a range of biophysical techniques including computational analysis, NMR spectroscopy, surface plasmon resonance, and fluorescence spectroscopy. HwTx-IV and mHwTx-IV exhibited weak affinity for lipid membranes, whereas gHwTx-IV showed improved affinity for the model membranes studied. In addition, activity assays using SH-SY5Y neuroblastoma cells expressing hNaV1.7 showed that gHwTx-IV has increased activity at hNaV1.7 compared to HwTx-IV. Based on these results we hypothesize that an increase in the affinity of HwTx-IV for lipid membranes is accompanied by improved inhibitory potency at hNaV1.7 and that increasing the affinity of gating modifier toxins to lipid bilayers is a strategy that may be useful for improving their potency at hNaV1.7

    Can a Logarithmically Running Coupling Mimic a String Tension?

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    It is shown that a Coulomb potential using a running coupling slightly modified from the perturbative form can produce an interquark potential that appears nearly linear over a large distance range. Recent high-statistics SU(2) lattice gauge theory data fit well to this potential without the need for a linear string-tension term. This calls into question the accuracy of string tension measurements which are based on the assumption of a constant coefficient for the Coulomb term. It also opens up the possibility of obtaining an effectively confining potential from gluon exchange alone.Comment: 13 pages, LaTeX, two figures not included, available from author. revision - Line lengths fixed so it will tex properl

    Role of family history and clinical screening in the identification of families with idiopathic dilated cardiomyopathy in Johannesburg, South Africa

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    Background. Familial disease is implicated in 20 - 50% of cases of idiopathic dilated cardiomyopathy (IDCM) worldwide. The contribution of familial factors to IDCM in the Johannesburg area, South Africa, is unknown.Objectives. To describe the demographic details of patients with IDCM who presented at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH), and to determine if there is evidence of familial disease through family history assessment and clinical screening of relatives.Methods. This was a single-centre, cohort study performed at a quaternary care centre at CMJAH. Fifty unrelated probands diagnosed with IDCM and available first- and second-degree relatives were included in the study. A three-generation family pedigree was drawn up for all 50 probands. The pedigrees were analysed to identify the presence or absence of familial disease and categorised as positive, intermediate, negative or unreliable according to the family history obtained. From the 50 proband cases, there were 21 family members available for screening for features of IDCM. Eighty-two family members (55 first-degree and 27 second-degree relatives) were screened clinically. Screening included a personal history, full physical examination, electrocardiogram (ECG) and echocardiogram.Results. The mean age at diagnosis of IDCM in the probands was 41.7 (standard deviation (SD) 12.4) years. The majority of probands were males (n=38; 76%). Of 50 pedigrees analysed, 14 (28%) were positive and likely to be indicative of familial dilated cardiomyopathy (DCM), and 9 (18%) patients were at intermediate risk of familial disease. Eighty-two asymptomatic family members were screened, with a median age of 33 (range 11 - 76) years. No asymptomatic family members were identified with features of DCM or presymptomatic DCM. Eleven of the 21 families screened had relatives with possible presymptomatic DCM identified by abnormalities on the echocardiogram in 3 families (14.3%) (4 individuals; all first-degree relatives of the index case) or identified on the basis of a conduction defect (an arrhythmia or first-/ second-/third-degree heart block) in 8 families (72.7%) (11 individuals; 9 first-degree and 2 second-degree relatives).Conclusions. Screening for IDCM should include a three-generation family history and clinical screening of all first-degree family members. As IDCM has an age-related penetrance, at-risk family members should receive follow-up for screening to assess symptoms and signs of IDCM. Genetic testing would potentially identify family members at high risk, who would benefit from screening; this might be a less expensive option

    The experiences of COVID-19 preprint authors: a survey of researchers about publishing and receiving feedback on their work during the pandemic

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    The COVID-19 pandemic caused a rise in preprinting, triggered by the need for open and rapid dissemination of research outputs. We surveyed authors of COVID-19 preprints to learn about their experiences with preprinting their work and also with publishing their work in a peer-reviewed journal. Our research had the following objectives: 1. to learn about authors’ experiences with preprinting, their motivations, and future intentions; 2. to consider preprints in terms of their effectiveness in enabling authors to receive feedback on their work; 3. to compare the impact of feedback on preprints with the impact of comments of editors and reviewers on papers submitted to journals. In our survey, 78% of the new adopters of preprinting reported the intention to also preprint their future work. The boost in preprinting may therefore have a structural effect that will last after the pandemic, although future developments will also depend on other factors, including the broader growth in the adoption of open science practices. A total of 53% of the respondents reported that they had received feedback on their preprints. However, more than half of the feedback was received through “closed” channels–privately to the authors. This means that preprinting was a useful way to receive feedback on research, but the value of feedback could be increased further by facilitating and promoting “open” channels for preprint feedback. Almost a quarter of the feedback received by respondents consisted of detailed comments, showing the potential of preprint feedback to provide valuable comments on research. Respondents also reported that, compared to preprint feedback, journal peer review was more likely to lead to major changes to their work, suggesting that journal peer review provides significant added value compared to feedback received on preprints
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