6,708 research outputs found

    No elliptic islands for the universal area-preserving map

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    A renormalization approach has been used in \cite{EKW1} and \cite{EKW2} to prove the existence of a \textit{universal area-preserving map}, a map with hyperbolic orbits of all binary periods. The existence of a horseshoe, with positive Hausdorff dimension, in its domain was demonstrated in \cite{GJ1}. In this paper the coexistence problem is studied, and a computer-aided proof is given that no elliptic islands with period less than 20 exist in the domain. It is also shown that less than 1.5% of the measure of the domain consists of elliptic islands. This is proven by showing that the measure of initial conditions that escape to infinity is at least 98.5% of the measure of the domain, and we conjecture that the escaping set has full measure. This is highly unexpected, since generically it is believed that for conservative systems hyperbolicity and ellipticity coexist

    Efficient metallic spintronic emitters of ultrabroadband terahertz radiation

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    Terahertz electromagnetic radiation is extremely useful for numerous applications such as imaging and spectroscopy. Therefore, it is highly desirable to have an efficient table-top emitter covering the 1-to-30-THz window whilst being driven by a low-cost, low-power femtosecond laser oscillator. So far, all solid-state emitters solely exploit physics related to the electron charge and deliver emission spectra with substantial gaps. Here, we take advantage of the electron spin to realize a conceptually new terahertz source which relies on tailored fundamental spintronic and photonic phenomena in magnetic metal multilayers: ultrafast photo-induced spin currents, the inverse spin-Hall effect and a broadband Fabry-P\'erot resonance. Guided by an analytical model, such spintronic route offers unique possibilities for systematic optimization. We find that a 5.8-nm-thick W/CoFeB/Pt trilayer generates ultrashort pulses fully covering the 1-to-30-THz range. Our novel source outperforms laser-oscillator-driven emitters such as ZnTe(110) crystals in terms of bandwidth, terahertz-field amplitude, flexibility, scalability and cost.Comment: 18 pages, 10 figure

    Effects of intervention upon precompetition state anxiety in elite junior tennis players: The relevance of the matching hypothesis

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    Reproduced with permission of publisher from: Terry, P., Coakley, L., & Karageorghis, C. Effects of intervention upon precompetition state anxiety in elite junior tennis players: the relevance of the matching hypothesis. Perceptual and Motor Skills, 1995, 81, 287-296. © Perceptual and Motor Skills 1995The matching hypothesis proposes that interventions for anxiety should be matched to the modality in which anxiety is experienced. This study investigated the relevance of the matching hypothesis for anxiety interventions in tennis. Elite junior tennis players (N = 100; Age: M = 13.9 yr., SD = 1.8 yr.) completed the Competitive State Anxiety Inventory-2 before and after one of four randomly assigned intervention strategies approximately one hour prior to competition at a National Junior Championship. A two-factor multivariate analysis of variance (group x time) with repeated measures on the time factor gave no significant main effect by group but indicated significant reductions in somatic anxiety and cognitive anxiety and a significant increase in self-confidence following intervention. A significant group by time interaction emerged for self-confidence. The results question the need to match intervention strategy to the mode of anxiety experienced

    К определению граничных элементов в рамках модели упругого грунтового слоя

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    В рамках расчетной схемы основания в виде слоя конечной толщины получены функции влияния матрицы податливости метода граничных элементов. Рассмотрена модель линейного упругого изотропного основания. Область применения полученных в работе результатов – определение напряженно-деформированного состояния (НДС) грунтовых оснований и расположенных на них фундаментов зданий и сооружений.Within the framework of calculation chart of founding as a layer of eventual thickness the functions of influence of matrix of pliability of method of border elements are got. The model of the linear resilient izotropic founding is considered. An application of the results got in-process domain is determination of the tensely-deformed state(VAT) of the ground grounds and foundations of building and building located on them

    Two- and three-body color flux tubes in the Chromo Dielectric Model

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    Using the framework of the Chromo Dielectric Model we perform an analysis of color electric flux tubes in meson-like qqˉq\bar{q} and baryon-like qqqqqq quark configurations. We discuss the Abelian color structure of the model and point out a symmetry in color space as a remnant of the SU(3) symmetry of QCD. The generic features of the model are discussed by varying the model parameters. We fix these parameters by reproducing the string tension τ=980\tau=980 MeV/fm and the transverse width ρ=0.35\rho=0.35 fm of the qqˉq\bar{q} flux tube obtained in lattice calculations. We use a bag constant B1/4=(240260)B^{1/4}=(240-260) MeV, a glueball mass mg=(10001700)m_g = (1000-1700) MeV and a strong coupling constant CFαs=0.20.3C_F \alpha_s = 0.2-0.3. We show that the asymptotic string profile of an infinitely long flux tube is already reached for qqˉq\bar{q} separations R1.0R\ge1.0 fm. A connection to the Dual Color Superconductor is made by extracting a magnetic current from the model equations and a qualitative agreement between the two descriptions of confinement is shown. In the study of the qqqqqq system we observe a Δ\mathsf{\Delta}-like geometry for the color electric fields and a \textsf{Y}-like geometry in the scalar fields both in the energy density distribution and in the corresponding potentials. The resulting total qqqqqq potential is described neither by the Δ\mathsf{\Delta}-picture nor by the \textsf{Y}-picture alone.Comment: 32 pages, 35 eps-figures, revised version, some references + 1 eps-file added, to be published in Phys.Rev.

    Early sCD8 plasma levels during subcutaneous rIl-2 therapy in patients with renal cell carcinoma correlate with response.

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    Plasma sIl-2R and sCD8 levels of 12 patients with renal cell carcinoma were determined before and during subcutaneous rIl-2 therapy. Patients with a complete/partial remission showed a significantly stronger initial increase of sCD8 compared to patients with stable disease or tumour progression

    Acute effects of ambient nitrogen oxides and interactions with temperature on cardiovascular mortality in Shenzhen, China

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    Background: Though inconsistent, acute effects of ambient nitrogen oxides on cardiovascular mortality have been reported. Whereas, interactive roles of temperature on their relationships and joint effects of different indicators of nitrogen oxides were less studied. This study aimed to extrapolate the independent roles of ambient nitrogen oxides and temperature interactions on cardiovascular mortality.Methods: Data on mortality, air pollutants, and meteorological factors in Shenzhen from 2013 to 2019 were collected. Three indicators including nitric oxide (NO), nitrogen dioxide (NO2), and nitrogen oxides (NOX) were studied. Adjusted generalized additive models (GAMs) were applied to analyse their associations with cardiovascular mortality in different groups.Results: The average daily concentrations of NO, NO2, and NOX were 11.7 mu g/m(3), 30.7 mu g/m(3), and 53.2 mu g/m(3), respectively. Significant associations were shown with each indicator. Cumulative effects of nitrogen oxides were more obvious than distributed lag effects. Males, population under 65 years old, and population with stroke related condition were more susceptible to nitrogen oxides. Adverse effects of nitrogen oxides were more significant at low temperature. Impacts of NO2 on cardiovascular mortality, and NO on stroke mortality were the most robust in the multi-pollutant models, whereas variations were shown in the other relationships.Conclusions: Low levels of nitrogen oxides showed acute and adverse impacts and the interactive roles of temperature on cardiovascular mortality. Cumulative effects were most significant and joint effects of nitrogen oxides required more attention. Population under 65 years old and population with stroke-related health condition were susceptible, especially days at lower temperature

    The acceptance and use of the e-Health instrument 'The personal health check' in four Dutch municipalities:Lessons learned

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    This pilot study assessed the acceptance and use of the e-Health instrument “the Personal Health Check” (PHC) among clients and professionals in primary care settings. By filling in the online PHC instrument, participants were provided insights into their health and lifestyle. When results revealed an increased health risk, participants were advised to undertake additional lab tests measuring blood pressure and haemaglobin levels. Based on the online questionnaire and optional lab tests, participants then received a report that included individually-tailored feedback from the e-Health application about personal health risks and suggestions for health interventions. The PHC was implemented in 2016 in four Dutch municipalities that determined which neighbourhood(s) the PHC targeted and how participants were invited. The Unified Theory of Acceptance and Use of Technology was used as a theoretical framework to address our research questions. Methods used to assess acceptance were: PHC instrument data, data from additional questionnaires completed by PHC participants, focus groups with PHC participants and professionals in primary care, and telephone interviews with non-responders to the invitation to participate in the online PHC. Of the 21,735 invited, 12% participated. Our results showed that participants and professionals in this pilot were predominantly positive about the PHC. Participants reported that they made an effort to apply the PHC lifestyle advice they received. Almost all had the knowledge and resources needed to use the PHC online instrument. Invitations from general practitioners almost doubled participation relative to invitations from the sponsoring municipalities. The overall low response rate, however, suggests that the PHC is unsuitable as a foundation on which to develop local public health policy
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