995 research outputs found

    Infrared finite solutions for the gluon propagator and the QCD vacuum energy

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    Nonperturbative infrared finite solutions for the gluon polarization tensor have been found, and the possibility that gluons may have a dynamically generated mass is supported by recent Monte Carlo simulation on the lattice. These solutions differ among themselves, due to different approximations performed when solving the Schwinger-Dyson equations for the gluon polarization tensor. Only approximations that minimize energy are meaningful, and, according to this, we compute an effective potential for composite operators as a function of these solutions in order to distinguish which one is selected by the vacuum.Comment: 16 pages, latex file, 1 postscript figure, uses epsf.sty and axodraw.sty. To be published in Phys. Lett.

    Considering the role of cognitive control in expert performance

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    © 2014, Springer Science+Business Media Dordrecht. Dreyfus and Dreyfus’ (1986) influential phenomenological analysis of skill acquisition proposes that expert performance is guided by non-cognitive responses which are fast, effortless and apparently intuitive in nature. Although this model has been criticised (e.g., by Breivik Journal of Philosophy of Sport, 34, 116–134 2007, Journal of the Philosophy of Sport, 40, 85–106 2013; Eriksen 2010; Montero Inquiry:An interdisciplinary Journal of Philosophy, 53, 105–122 2010; Montero and Evans 2011) for over-emphasising the role that intuition plays in facilitating skilled performance, it does recognise that on occasions (e.g., when performance goes awry for some reason) a form of ‘detached deliberative rationality’ may be used by experts to improve their performance. However, Dreyfus and Dreyfus (1986) see no role for calculative problem solving or deliberation (i.e., drawing on rules or mental representations) when performance is going well. In the current paper, we draw on empirical evidence, insights from athletes, and phenomenological description to argue that ‘continuous improvement’ (i.e., the phenomenon whereby certain skilled performers appear to be capable of increasing their proficiency even though they are already experts; Toner and Moran 2014) among experts is mediated by cognitive (or executive) control in three distinct sporting situations (i.e., in training, during pre-performance routines, and while engaged in on-line skill execution). We conclude by arguing that Sutton et al. Journal of the British Society for Phenomenology, 42, 78–103 (2011) ‘applying intelligence to the reflexes’ (AIR) approach may help to elucidate the process by which expert performers achieve continuous improvement through analytical/mindful behaviour during training and competition

    Microclimate evaluation of a new design of insect-proof screens in a Mediterranean greenhouse

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    This work studies natural ventilation in a Mediterranean greenhouse, comparing a new experimental screen of 13×30 threads cm-2 (porosity 39.0%) with a commercial control screen of 10×20 threads cm-2 (porosity 33.5%). In addition, both screens were tested in a wind tunnel to determine the discharge coefficients Cd of the greenhouse side and roof vents, which proved to be 0.16 for the commercial control screen and 0.18 for the experimental screen at both vents. These values represent a theoretical increase of 11% (Cd,φ-10×20 /Cd,φ-13×30 = 0.89) in the natural ventilation capacity of the greenhouse when the experimental screen is used. The greenhouse was divided into two separate sections allowing us to analyze natural ventilation in both sectors simultaneously. Air velocity was measured in the lateral and roof vents with two 3D and six 2D sonic anemometers. Using the commercial control screen there was an average reduction of 16% in ventilation rate, and an average increase of 0.5ºC in the average indoor air temperature, compared to the experimental screen. In addition, the ventilation efficiency ηT was higher with the experimental screen (mean value of 0.9) than with the control (mean value 0.6). We have designed an experimental insect-proof screen (13×30 threads cm-2) with smaller thread diameter, higher thread density, smaller pore size and higher porosity than are used in most commercial meshes. All of these factors promote natural ventilation and improve the greenhouse microclimate.</p

    Coming Together: R&D and Children's Entertainment Company in Designing APPs for Learning Early Math

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    Information and Communication Technologies (ICT) have an increasing influence on the way we interact, learn, and live. The increase in teaching and learning methodologies that are mediated by ICT in the field of education and in the domestic settings encourages the design of new effective technological tools, supported by scientific research and development to improve student learning. The challenge psychology is facing in the education field is to promote those technologies and make them available to the education community. Technologies also would produce attractive items for users and realistic commercial issues for businesses. This also allows an effective transfer for scientific work, providing visibility to Research and Development. In this context, the main aim of the article is to describe the process to get an agreement between Babyradio (a children’s entertainment company: https://babyradio.es/) and our research team, starting a collaborative work between two groups of people (Babyradio’s technical designer and Psychologist-Engineers software designer), in order to create several educative applications (APPs) in the field of early mathematics cognition. The institutional framework of the relationship of the R&D project and a children’s entertainment company is described. The article also focuses on experience in Psychology, Technological Innovation, and Entrepreneurship. In considering the efficiency of the agreement, we present different APPs designed for tablets and smartphone devices, adapted to the different operating systems (IOS, Android, Windows). APPs are designed to instill the cognitive fundamentals associated with early math learning for students aged 4 to 7 years. The study developed after this babyradio-university enterprise agreement contributes to the development of mathematics skills in children, aged 4–7 years, so that they can successfully meet the mathematics school requirements; it also contributes to encouraging a more positive attitude toward mathematics. This study also suggests how the education system and software and educational content developers’ companies would manage verified instructional APPs, with a more realistic commercial perspective

    Normal aortic diameters within the Mexican population and the impact of gender and ethnicity

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    Background: There is a lack of studies describing the normal size of the aorta in Mexican population. Objective: To analyze aortic measurements in Mexican patients and to compared them with patients from five different countries. Methods: Measurements of the aorta were divided in Mexicans and controls. Comparisons between ethnicities and groups were performed using Mann Whitney rank sum test. Results: The registry included 166 patients, 106 (63.8%) were enrolled in Mexico and 60 (36.1%) in the control group. Mexican patients had smaller aortic diameters compared to the control group, at the level of the right renal artery ostium, inferior mesenteric artery, and aortic bifurcation. The Hispanic population had significantly smaller aortic diameters from the level of the celiac artery to the aortic bifurcation. Conclusion: The normal aortic diameters in the Mexican population are smaller compared to other countries.</p

    Structural Transitions and Global Minima of Sodium Chloride Clusters

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    In recent experiments on sodium chloride clusters structural transitions between nanocrystals with different cuboidal shapes were detected. Here we determine reaction pathways between the low energy isomers of one of these clusters, (NaCl)35Cl-. The key process in these structural transitions is a highly cooperative rearrangement in which two parts of the nanocrystal slip past one another on a {110} plane in a direction. In this way the nanocrystals can plastically deform, in contrast to the brittle behaviour of bulk sodium chloride crystals at the same temperatures; the nanocrystals have mechanical properties which are a unique feature of their finite size. We also report and compare the global potential energy minima for (NaCl)NCl- using two empirical potentials, and comment on the effect of polarization.Comment: extended version, 13 pages, 8 figures, revte

    Marketing strategy of the hospitality industry

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    Budući da se gospodarstvo sve više razvija u smjeru uslužnih djelatnosti, nameće se potreba da marketing manageri, marketing stručnjaci i poduzetnici, što bolje upoznaju uslužne djelatnosti i njihovu važnost za gospodarstvo svake zemlje, pa i Hrvatske. Usluge su neopipljive, nedjeljive, nepostojane i prolazne, pa svaki oblik usluga zahtijeva marketing strategiju. Naime, gospodarska uslužna djelatnost omogućava proizvodnji da premosti prostor ili segmente tržišta između proizvodnje i potrošnje, kako bi se u određenom vremenu i prostoru učinkovito zadovoljile potrebe potrošača i ostvarili ciljevi poduzeća, uz planiranu dobit ili profit. U prošlosti, uslužne djelatnosti su znatno zaostajale za proizvodnim poduzećima u usvajanju i primjeni marketing koncepcije, no sada se to znatno mijenja. Sukladno s iznesenim, marketing strategija u uslužnim djelatnostima zahtijeva ne samo vanjski marketing, već i marketing unutar poduzeća, kako bi se motivirali djelatnici u pružanju usluga i podizanju razine kvalitete.Considering the current growth of the hospitality industry, the marketing managers, experts and entrepreneurs should become aware of the growing importance of various hospitality services for the overall industry of each country including the Republic of Croatia. The services rendered in the hospitality sphere are intangible and unsteady in nature so that each domain necessarily requires a separate marketing strategy. Namely, hospitality services render it possible for the production to span the space, i.e. the different market segments between the supply and demand and meet the consumers needs as well as to achieve the set objectives. In the past years the hospitality industry was considerably falling behind other business enterprises and organizations in the adoption and application of appropriate marketing concepts. It seems, however, that the situation has turned for the better. The hospitality services clearly demand not only an exterior marketing strategy but also a proper marketing technique inside individual establishments in order to achieve a higher level of motivation among the hospitality staff as well as a better quality of service

    Intact protein folding in the glutathione-depleted endoplasmic reticulum implicates alternative protein thiol reductants

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    Protein folding homeostasis in the endoplasmic reticulum (ER) requires efficient protein thiol oxidation, but also relies on a parallel reductive process to edit disulfides during the maturation or degradation of secreted proteins. To critically examine the widely held assumption that reduced ER glutathione fuels disulfide reduction, we expressed a modified form of a cytosolic glutathione-degrading enzyme, ChaC1, in the ER lumen. ChaC1(CtoS) purged the ER of glutathione eliciting the expected kinetic defect in oxidation of an ER-localized glutathione-coupled Grx1-roGFP2 optical probe, but had no effect on the disulfide editing-dependent maturation of the LDL receptor or the reduction-dependent degradation of misfolded alpha-1 antitrypsin. Furthermore, glutathione depletion had no measurable effect on induction of the unfolded protein response (UPR); a sensitive measure of ER protein folding homeostasis. These findings challenge the importance of reduced ER glutathione and suggest the existence of alternative electron donor(s) that maintain the reductive capacity of the ER.Wellcome Trust [084812/Z/08/Z, 100140]; European Commission EU [277713]; Fundacao para a Ciencia e a Tecnologia [PTDC/QUI-BIQ/119677/2010]info:eu-repo/semantics/publishedVersio

    Limits on different Majoron decay modes of 100^{100}Mo and 82^{82}Se for neutrinoless double beta decays in the NEMO-3 experiment

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    The NEMO-3 tracking detector is located in the Fr\'ejus Underground Laboratory. It was designed to study double beta decay in a number of different isotopes. Presented here are the experimental half-life limits on the double beta decay process for the isotopes 100^{100}Mo and 82^{82}Se for different Majoron emission modes and limits on the effective neutrino-Majoron coupling constants. In particular, new limits on "ordinary" Majoron (spectral index 1) decay of 100^{100}Mo (T1/2>2.71022T_{1/2} > 2.7\cdot10^{22} y) and 82^{82}Se (T1/2>1.51022T_{1/2} > 1.5\cdot10^{22} y) have been obtained. Corresponding bounds on the Majoron-neutrino coupling constant are <(0.41.9)104 < (0.4-1.9) \cdot 10^{-4} and <(0.661.7)104< (0.66-1.7) \cdot 10^{-4}.Comment: 23 pages includind 4 figures, to be published in Nuclear Physics
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