218 research outputs found

    What traits are carried on mobile genetic elements, and why?

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    Although similar to any other organism, prokaryotes can transfer genes vertically from mother cell to daughter cell, they can also exchange certain genes horizontally. Genes can move within and between genomes at fast rates because of mobile genetic elements (MGEs). Although mobile elements are fundamentally self-interested entities, and thus replicate for their own gain, they frequently carry genes beneficial for their hosts and/or the neighbours of their hosts. Many genes that are carried by mobile elements code for traits that are expressed outside of the cell. Such traits are involved in bacterial sociality, such as the production of public goods, which benefit a cell's neighbours, or the production of bacteriocins, which harm a cell's neighbours. In this study we review the patterns that are emerging in the types of genes carried by mobile elements, and discuss the evolutionary and ecological conditions under which mobile elements evolve to carry their peculiar mix of parasitic, beneficial and cooperative genes

    Large tunable valley splitting in edge-free graphene quantum dots on boron nitride

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    Coherent manipulation of binary degrees of freedom is at the heart of modern quantum technologies. Graphene offers two binary degrees: the electron spin and the valley. Efficient spin control has been demonstrated in many solid state systems, while exploitation of the valley has only recently been started, yet without control on the single electron level. Here, we show that van-der Waals stacking of graphene onto hexagonal boron nitride offers a natural platform for valley control. We use a graphene quantum dot induced by the tip of a scanning tunneling microscope and demonstrate valley splitting that is tunable from -5 to +10 meV (including valley inversion) by sub-10-nm displacements of the quantum dot position. This boosts the range of controlled valley splitting by about one order of magnitude. The tunable inversion of spin and valley states should enable coherent superposition of these degrees of freedom as a first step towards graphene-based qubits

    The emergence of reciprocally beneficial cooperation

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    We offer a new and robust model of the emergence and persistence of cooperation when interactions are anonymous, the population is well-mixed, and evolution selects strategies according to material payoffs. The model has a Prisoner’s Dilemma structure, but with an outside option of non-participation. The payoff to mutual cooperation is stochastic; with positive probability, it exceeds that from cheating against a cooperator. Under mild conditions, mutually beneficial cooperation occurs in equilibrium. This is possible because the non-participation option holds down the equilibrium frequency of cheating. Dynamic properties of the model are investigated theoretically and through simulations based on replicator dynamics

    Acute thrombosis of the superior mesenteric artery in a 39-year-old woman with protein-S deficiency: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Acute thromboembolic occlusion of the superior mesenteric artery is a condition with an unfavorable prognosis. Treatment of this condition is focused on early diagnosis, surgical or intravascular restoration of blood flow to the ischemic intestine, surgical resection of the necrotic bowel and supportive intensive care. In this report, we describe a case of a 39-year-old woman who developed a small bowel infarct because of an acute thrombotic occlusion of the superior mesenteric artery, also involving the splenic artery.</p> <p>Case presentation</p> <p>A 39-year-old Caucasian woman presented with acute abdominal pain and signs of intestinal occlusion. The patient was given an abdominal computed tomography scan and ultrasonography in association with Doppler ultrasonography, highlighting a thrombosis of the celiac trunk, of the superior mesenteric artery, and of the splenic artery. She immediately underwent an explorative laparotomy, and revascularization was performed by thromboendarterectomy with a Fogarty catheter. In the following postoperative days, she was given a scheduled second and third look, evidencing necrotic jejunal and ileal handles. During all the surgical procedures, we performed intraoperative Doppler ultrasound of the superior mesenteric artery and celiac trunk to control the arterial flow without evidence of a new thrombosis.</p> <p>Conclusion</p> <p>Acute mesenteric ischemia is a rare abdominal emergency that is characterized by a high mortality rate. Generally, acute mesenteric ischemia is due to an impaired blood supply to the intestine caused by thromboembolic phenomena. These phenomena may be associated with a variety of congenital prothrombotic disorders. A prompt diagnosis is a prerequisite for successful treatment. The treatment of choice remains laparotomy and thromboendarterectomy, although some prefer an endovascular approach. A second-look laparotomy could be required to evaluate viable intestinal handles. Some authors support a laparoscopic second-look. The possibility of evaluating the arteriotomy, during a repeated laparotomy with a Doppler ultrasound, is crucial to show a new thrombosis. Although the prognosis of acute mesenteric ischemia due to an acute arterial mesenteric thrombosis remains poor, a prompt diagnosis, aggressive surgical treatment and supportive intensive care unit could improve the outcome for patients with this condition.</p

    Relationship between Obesity and Depression in the Korean Working Population

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    This study was conducted to investigate potential relationship between obesity and depression in Korean working population. A total of 8,121 workers, aged 21-75 yr, participated in this nationwide cross-section research. The participants asked to complete a questionnaire regarding the socio-demographic factors and health-related behaviors, height, and weight. To measure degree of depression, the Korean version of the Center for Epidemiologic Studies-Depression scale (CES-D) was used. Chi-square test and multivariate logistic regression analyses were performed to examine the degree of association between obesity and depression. Compared to normal-weight women, overweight women had a lower adjusted odds ratio (OR) for depression (OR=0.65, 95% confidence interval 0.46 to 0.97). Underweight (1.42, 0.83 to 2.44) and obese women (BMI ≥30) had higher ORs for depression (1.47, 0.64 to 3.36), but these were insignificant. Compared to normal-weight men, obese men had higher crude ORs (1.94, 1.03 to 3.62) and adjusted ORs (1.77, 0.89 to 3.53) for depression, while underweight and overweight men showed no significant differences. These findings suggest that being overweight may protect Korean female worker against depression

    A Bayesian Network Driven Approach to Model the Transcriptional Response to Nitric Oxide in Saccharomyces cerevisiae

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    The transcriptional response to exogenously supplied nitric oxide in Saccharomyces cerevisiae was modeled using an integrated framework of Bayesian network learning and experimental feedback. A Bayesian network learning algorithm was used to generate network models of transcriptional output, followed by model verification and revision through experimentation. Using this framework, we generated a network model of the yeast transcriptional response to nitric oxide and a panel of other environmental signals. We discovered two environmental triggers, the diauxic shift and glucose repression, that affected the observed transcriptional profile. The computational method predicted the transcriptional control of yeast flavohemoglobin YHB1 by glucose repression, which was subsequently experimentally verified. A freely available software application, ExpressionNet, was developed to derive Bayesian network models from a combination of gene expression profile clusters, genetic information and experimental conditions

    Risk of malnutrition is associated with mental health symptoms in community living elderly men and women: The Tromsø Study

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    <p>Abstract</p> <p>Background</p> <p>Little research has been done on the relationship between malnutrition and mental health in community living elderly individuals. In the present study, we aimed to assess the associations between mental health (particularly anxiety and depression) and both the risk of malnutrition and body mass index (BMI, kg/m<sup>2</sup>) in a large sample of elderly men and women from Tromsø, Norway.</p> <p>Methods</p> <p>In a cross-sectional survey, with 1558 men and 1553 women aged 65 to 87 years, the risk of malnutrition was assessed by the Malnutrition Universal Screening Tool ('MUST'), and mental health was measured by the Symptoms Check List 10 (SCL-10). BMI was categorised into six groups (< 20.0, 20.0-22.4, 22.5-24.9, 25.0-27.4, 27.5-29.9, ≥ 30.0 kg/m<sup>2</sup>).</p> <p>Results</p> <p>The risk of malnutrition (combining medium and high risk) was found in 5.6% of the men and 8.6% of the women. Significant mental health symptoms were reported by 3.9% of the men and 9.1% of the women. In a model adjusted for age, marital status, smoking and education, significant mental health symptoms (SCL-10 score ≥ 1.85) were positively associated with the risk of malnutrition (odds ratio 3.9 [95% CI 1.7-8.6] in men and 2.5 [95%CI 1.3-4.9] in women), the association was positive also for subthreshold mental health symptoms. For individuals with BMI < 20.0 the adjusted odds ratio for significant mental health symptoms was 2.0 [95% CI 1.0-4.0].</p> <p>Conclusions</p> <p>Impaired mental health was strongly associated with the risk of malnutrition in community living elderly men and women and this association was also significant for subthreshold mental health symptoms.</p

    The desirability of transitions in demand: Incorporating behavioural and societal transformations into energy modelling

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    Quantitative systems modelling in support of climate policy has tended to focus more on the supply side in assessing interactions among technology, economy, environment, policy and society. By contrast, the demand side is usually underrepresented, often emphasising technological options for energy efficiency improvements. In this perspective, we argue that scientific support to climate action is not only about exploring capacity of "what", in terms of policy and outcome, but also about assessing feasibility and desirability, in terms of "when", "where" and especially for "whom". Without the necessary behavioural and societal transformations, the world faces an inadequate response to the climate crisis challenge. This could result from poor uptake of low-carbon technologies, continued high-carbon intensive lifestyles, or economy-wide rebound effects. For this reason, we propose a framing for a holistic and transdisciplinary perspective on the role of human choices and behaviours in influencing the low-carbon transition, starting from the desires of individuals and communities, and analysing how these interact with the energy and economic landscape, leading to systemic change at the macro-level. In making a case for a political ecology agenda, we expand our scope, from comprehending the role of societal acceptance and uptake of end-use technologies, to co-developing knowledge with citizens from non-mainstream and marginalised communities, and to defining the modelling requirements to assess the decarbonisation potential of shifting lifestyle patterns in climate change and action

    Economic Impact of Dengue Illness and the Cost-Effectiveness of Future Vaccination Programs in Singapore

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    Dengue illness is a tropical disease transmitted by mosquitoes that threatens more than one third of the worldwide population. Dengue has important economic consequences because of the burden to hospitals, work absenteeism and risk of death of symptomatic cases. Governments attempt to reduce the disease burden using costly mosquito control strategies such as habitat reduction and spraying insecticide. Despite such efforts, the number of cases remains high. Dengue vaccines are expected to be available in the near future and there is an urgent need to evaluate their cost-effectiveness, i.e. whether their cost will be justified by the reduction in disease burden they bring. For such an evaluation, we estimated the economic impacts of dengue in Singapore and the expected vaccine costs for different prices. In this way we estimated price thresholds for which vaccination is not cost-effective. This research provides useful estimates that will contribute to informed decisions regarding the adoption of dengue vaccination programs

    On the causes of economic growth in Europe: why did agricultural labour productivity not converge between 1950 and 2005?

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    The objective of this study is to make a further contribution to the debate on the causes of economic growth in the European Continent. It explains why agricultural labour productivity differences did not converge between 1950 and 2005 in Europe. We propose an econometric model, one combining both proximate and fundamental causes of economic growth. The results show that the continuous exit of labour power from the sector, coupled with the increased use of productive factors originating in other sectors of the economy, caused the efficiency of agricultural workers to rise. However, we offer a complete explanation of the role played by institutions and geographical factors. Thus, we detect a direct and inverse relation between membership of the EU and the Communist bloc and the productivity of agricultural labour. In addition, strong support for agriculture affected productivity negatively
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