5,152 research outputs found

    The Benefits of a Challenge Approach on Match Day: Investigating Cardiovascular Reactivity in Professional Academy Soccer Players.

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    This study assessed physiological (cardiovascular) and psychological (confidence, control, and approach focus) data in professional academy soccer players prior to performance in competitive matches. A challenge state is characterised by an increase in cardiac output (CO), and a decrease in total peripheral vascular resistance (TPR). Data were collected from 37 participants, with 19 of these providing data on two separate occasions. Performance was measured using coach and player self-ratings. Challenge reactivity was positively, and significantly, associated with performance. Participants who demonstrated blunted cardiovascular (CV) responses performed significantly worse than participants who displayed either challenge or threat reactivity. There was mixed consistency in CV reactivity for those participants whose data were collected on more than one occasion, suggesting that some participants responded differently across the competitive matches. The association between self-report data and CV responses was weak. This study supports previous research demonstrating that challenge reactivity is associated with superior performance

    Geometric quantum computation with NMR

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    The experimental realisation of the basic constituents of quantum information processing devices, namely fault-tolerant quantum logic gates, requires conditional quantum dynamics, in which one subsystem undergoes a coherent evolution that depends on the quantum state of another subsystem. In particular, the subsystem may acquire a conditional phase shift. Here we consider a novel scenario in which this phase is of geometric rather than dynamical origin. As the conditional geometric (Berry) phase depends only on the geometry of the path executed it is resilient to certain types of errors, and offers the potential of an intrinsically fault-tolerant way of performing quantum gates. Nuclear Magnetic Resonance (NMR) has already been used to demonstrate both simple quantum information processing and Berry's phase. Here we report an NMR experiment which implements a conditional Berry phase, and thus a controlled phase shift gate. This constitutes the first elementary geometric quantum computation.Comment: Minor additions at request of referees. 4 pages revtex including 2 figures (1 eps). Nature in pres

    The "Home Advantage" in Athletic Competitions

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    Game location has a powerful influence on performance outcomes in sport. We reviewed recent research on three conceptual models that outline (a) the various game-location factors that can alter athletes' psychological states, (b) the natural protective response to territorial incursion in humans, and (c) the increased probability of involuntary attentional shifts in the presence of a supportive audience. Investigators recently have accumulated support for each of these models and linked variations in game location to psychological, hormonal, and behavioral states of athletes, coaches, and officials. We considered how an integrative approach might benefit the study of the home-advantage phenomenon and described an assortment of research questions to support the development of an integrative framework. By studying how audience support contributes to physiological reactivity, attention, stress responses, and decision making (among athletes and officials), researchers can achieve a better understanding of the processes through which a home environment can benefit (and occasionally harm) athletes and teams. © The Author(s) 2014

    Factors affecting sporulation and infection of Peronospora sparsa in New Zealand boysenberry gardens

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    Downy mildew, caused by Peronospora sparsa, is an economically important disease of boysenberries. Sporangia produced on infected tissue initiate berry infections; however the timing of sporangial release under New Zealand environmental conditions is unknown. The number of P. sparsa sporangia trapped on Vaseline®-coated slides placed weekly in three boysenberry gardens in the Nelson region from October to December in 2010 and September to December in 2011 was determined. Climate data were used to determine environmental factors that promoted sporangia production/release. Incidence of dryberry symptoms and sporulation on tissue samples incubated at 15 or 20°C under high relative humidity (RH) were assessed. Peronospora sparsa sporangia were observed on slides from all three sites, with peak sporangial numbers in mid-November in both years. Sites with the highest numbers of sporangia trapped in November had higher dryberry incidence in December. Data indicated that sporangial release was triggered by percentage of rainy days, RH and warm temperatures (16-23°C) in early spring, where high moisture periods promoted sporulation and a subsequent dry period allowed sporangial release. This study improves understanding of the timing of sporangial release to inform management practices

    Thermodynamics of hydrogen production from urea by steam reforming with and without in situ carbon dioxide sorption

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    The thermodynamic effects of molar steam to carbon ratio (S:C), of pressure, and of having CaO present on the H2 yield and enthalpy balance of urea steam reforming were investigated. At a S:C of 3 the presence of CaO increased the H2 yield from 2.6 mol H2/mol urea feed at 940 K to 2.9 at 890 K, and decreased the enthalpy of bringing the system to equilibrium. A minimum enthalpy of 180.4 kJ was required to produce 1 mol of H2 at 880 K. This decreased to 94.0 kJ at 660 K with CaO-based CO2 sorption and, when including a regeneration step of the CaCO3 at 1170 K, to 173 kJ at 720 K. The presence of CaO allowed widening the range of viable operation at lower temperature and significantly inhibited carbon formation. The feasibility of producing H2 from renewable urea in a low carbon future is discussed

    Uncertainty in geometry of fibre preforms manufactured with Automated Dry Fibre Placement (ADFP) and its effects on permeability

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    Resin transfer moulding is one of several processes available for manufacturing fibre-reinforced composites from dry fibre reinforcement. Recently, dry reinforcements made with Automated Dry Fibre Placement have been introduced into the aerospace industry. Typically, the permeability of the reinforcement is assumed to be constant throughout the dry preform geometry whereas in reality it possesses inevitable uncertainty due to variability in geometry. This uncertainty propagates to the uncertainty of the mould filling and the fill time, one of the important variables in resin injection. It makes characterisation of the permeability and its variability an important task for design of the resin transfer moulding process. In this study, variability of the geometry of a reinforcement manufactured using Automated Dry Fibre Placement is studied. Permeability of the manufactured preforms is measured experimentally and compared to stochastic simulations based on an analytical model and a stochastic geometry model. The simulations showed that difference between the actual geometry and the designed geometry can result in 50% reduction of the permeability. The stochastic geometry model predicts results within 20% of the experimental values

    Biotic carbon feedbacks in a materially-closed soil-vegetation-atmosphere system

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    The magnitude and direction of the coupled feedbacks between the biotic and abiotic components of the terrestrial carbon cycle is a major source of uncertainty in coupled climate–carbon-cycle models1, 2, 3. Materially closed, energetically open biological systems continuously and simultaneously allow the two-way feedback loop between the biotic and abiotic components to take place4, 5, 6, 7, but so far have not been used to their full potential in ecological research, owing to the challenge of achieving sustainable model systems6, 7. We show that using materially closed soil–vegetation–atmosphere systems with pro rata carbon amounts for the main terrestrial carbon pools enables the establishment of conditions that balance plant carbon assimilation, and autotrophic and heterotrophic respiration fluxes over periods suitable to investigate short-term biotic carbon feedbacks. Using this approach, we tested an alternative way of assessing the impact of increased CO2 and temperature on biotic carbon feedbacks. The results show that without nutrient and water limitations, the short-term biotic responses could potentially buffer a temperature increase of 2.3 °C without significant positive feedbacks to atmospheric CO2. We argue that such closed-system research represents an important test-bed platform for model validation and parameterization of plant and soil biotic responses to environmental changes

    Hair cortisol and self-reported stress in healthy, working adults

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    © 2015 Elsevier Ltd. Chronic stress can be important in the pathology of chronic disease. Hair cortisol concentrations (HCC) are proposed to reflect long term cortisol secretion from exposure to stress. To date, inconsistencies in the relationship between HCC and self-reported stress have been attributed to variation and limitations of perceived stress measurement. We report data from employees of two large public sector worksites (n = 132). Socio-demographic, health, lifestyle, perceived stress scale (PSS), and work-related effort reward imbalance (ERI) were collected at baseline. Participants were asked to respond to mobile text messages every two days, asking them to report current stress levels (Ecological momentary assessment, EMA), and mean stress was determined overall, during work hours, and out of work hours. At 12 weeks, the appraisal of stressful life events scale (ALES) was completed and 3. cm scalp hair samples were taken, from which HCC was determined (to reflect cortisol secretion over the past 12 weeks). Mean response rate to EMA was 81.9. ± 14.9%. Associations between HCC and the various self-reported stress measures (adjusted for use of hair dye) were weak (all < .3). We observed significant associations with HCC for EMA measured stress responses received out of work hours (ρ = .196, p = .013) and ALES Loss subscale (ρ = .241, p = .003), and two individual items from ERI (relating to future work situation). In regression analysis adjusting for other possible confounders, only the HCC-ALES Loss association remained significant (p = .011). Overall, our study confirms that EMA provides a useful measurement tool that can gather perceived stress measures in real-time. But, there was no relationship between self-reported stress collected in this way, and HCC. The modest association between HCC and stress appraisal does however, provide some evidence for the role of cognitive processes in chronic stress

    Natural environments and chronic stress measured by hair cortisol

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    © 2015 Elsevier B.V. Neighbourhood green space is positively associated with health. Stress reducing effects of nature might underpin this relationship, but researchers have often used objective stress measures to characterise acute responses to natural environments, or used self-reported measures in observational research. Hair cortisol concentration (HCC) is a novel non-invasive biomarker, with potential to improve our understanding of natural environments and chronic stress. We collected data from 132 healthy employed adults from the West Midlands region of the UK (June-Sept 2014). Data included socio-demographics, health, lifestyle perceived stress and stress appraisal. Postcode was used to determine overall deprivation (Index of Multiple Deprivation, IMD), material deprivation (% income deprived) and the amount of natural environment in participants' home neighbourhoods. Hair samples (3 cm) were taken from the scalp and HCC was determined to reflect past three months of cortisol secretion. Separate linear regression models, adjusting for potential confounders, indicated that HCC-measured chronic stress was higher in participants who lived in areas that were more deprived overall (β= -.235, p= .008), more income deprived (β = -.219, p = .017), and lower area density of natural environment (β= -.212, p= .019). When income deprivation (i.e., material well-being) and natural environment were entered in the same model, associations for both were attenuated beyond significance (β=168, p= .077 and β= -160, p= .086, respectively). Overall, chronic stress measured by HCC was higher in areas with less natural environment. The relative contribution of neighbourhood n atural environment, deprivation and other neighbourhood characteristics to chronic stress using HCC warrants further study in larger, more diverse samples

    TAp73 contributes to the oxidative stress response by regulating protein synthesis.

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    TAp73 is a transcription factor that plays key roles in brain development, aging, and cancer. At the cellular level, TAp73 is a critical homeostasis-maintaining factor, particularly following oxidative stress. Although major studies focused on TAp73 transcriptional activities have indicated a contribution of TAp73 to cellular metabolism, the mechanisms underlying its role in redox homeostasis have not been completely elucidated. Here we show that TAp73 contributes to the oxidative stress response by participating in the control of protein synthesis. Regulation of mRNA translation occupies a central position in cellular homeostasis during the stress response, often by reducing global rates of protein synthesis and promoting translation of specific mRNAs. TAp73 depletion results in aberrant ribosomal RNA (rRNA) processing and impaired protein synthesis. In particular, polysomal profiles show that TAp73 promotes the integration of mRNAs that encode rRNA-processing factors in polysomes, supporting their translation. Concurrently, TAp73 depletion causes increased sensitivity to oxidative stress that correlates with reduced ATP levels, hyperactivation of AMPK, and translational defects. TAp73 is important for maintaining active translation of mitochondrial transcripts in response to oxidative stress, thus promoting mitochondrial activity. Our results indicate that TAp73 contributes to redox homeostasis by affecting the translational machinery, facilitating the translation of specific mitochondrial transcripts. This study identifies a mechanism by which TAp73 contributes to the oxidative stress response and describes a completely unexpected role for TAp73 in regulating protein synthesis
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