2,481 research outputs found

    N=2 SUGRA BPS multi-center black holes and freudenthal triple systems

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    We present a detailed description of N = 2 stationary BPS multicenter black hole solutions for quadratic prepotentials with an arbitrary number of centers and scalar fields making a systematic use of the algebraic properties of the matrix of second derivatives of the prepotential, S, which in this case is a scalar-independent matrix. The anti-involution matrix S can be understood as a Freudenthal duality x̃ = Sx. We show that this duality can be generalized to “Freudenthal transformations”

    Air gap influence on the vibro-acoustic response of Solar Arrays during launch

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    One of the primary elements on the space missions is the electrical power subsystem, for which the critical component is the solar array. The behaviour of these elements during the ascent phase of the launch is critical for avoiding damages on the solar panels, which are the primary source of energy for the satellite in its final configuration. The vibro-acoustic response to the sound pressure depends on the solar array size, mass, stiffness and gap thickness. The stowed configuration of the solar array consists of a multiple system composed of structural elements and the air layers between panels. The effect of the air between panels on the behaviour of the system affects the frequency response of the system not only modifying the natural frequencies of the wings but also as interaction path between the wings of the array. The usual methods to analyze the vibro-acoustic response of structures are the FE and BE methods for the low frequency range and the SEA formulation for the high frequency range. The main issue in the latter method is, on one hand, selecting the appropriate subsystems, and, on the other, identifying the parameters of the energetic system: the internal and coupling loss factors. From the experimental point of view, the subsystems parameters can be identified by exciting each subsystem and measuring the energy of all the subsystems composing the Solar Array. Although theoretically possible, in practice it is difficult to apply loads on the air gaps. To analyse this situation, two different approaches can be studied depending on whether the air gaps between the panels are included explicitly in the problem or not. For a particular case of a solar array of three wings in stowed configuration both modelling philosophies are compared. This stowed configuration of a three wing solar arrays in stowed configuration has been tested in an acoustic chamber. The measured data on the solar wings allows, in general, determining the loss factors of the configuration. The paper presents a test description and measurements on the structure, in terms of the acceleration power spectral density. Finally, the performance of each modelling technique has been evaluated by comparison between simulations with experimental results on a spacecraft solar array and the influence on the apparent properties of the system in terms of the SEA loss factors has been analyse

    Expression of the alpha-thionin gene from barley in tobacco confers enhanced resistance to bacterial pathogens

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    Thionins are cysteine-rich, 5 kDa polypeptides which are toxic to plant pathogens in vitro. Expression of the gene encoding alpha-thionin from barley endosperm, under the 35S promoter from cauliflower mosaic virus, conferred to transgenic tobacco enhanced resistance to the bacterial plant pathogens Pseudomonas syringae pv. tabaci 153 and P. syringae pv. syringae. The barley alpha-thionin gene, which has two introns, was correctly spliced in tobacco. The alpha-thionin in transgenic plants had the expected mobility in the gradient, when separated by high- performance liquid chromatography, reacted with monospecific antibodies and showed the expected antibiotic properties in vitr

    The Effects of Two Different Resisted Swim Training Load Protocols on Swimming Strength and Performance

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    This study used a power rack device to evaluate the effects of 2 different approaches to resisted swim training loads on swimming strength and performance. Sixteen male, youth national-level swimmers (mean age, 16.22 +/- 2.63 years; body height, 169 +/- 10.20 cm; body mass, 61.33 +/- 9.90 kg) completed a 6-week specific strength-training program, and were then randomly assigned to one of the two groups: a standard training group (GS, n = 8) and a flat pyramid-loading pattern group (GP, n = 8). Strength and power tests along with specific swimming tests (50-m crawl and 50-m competition-style time trials) were conducted at baseline (pre-test), before the third week (mid-test), and after 6 weeks of intervention (post-test). Isokinetic swim bench tests were conducted to obtain measurements of force production and power, and 1RM tests with the power rack system were conducted to measure the maximum drag load (MDL) and specific swimming power. Following 6 weeks of intervention, the mean MDL increased (p < 0.05) by 13.94%. Scores for the 50-m competition style and 50-m crawl time trials improved by 0.32% and 0.78%, respectively, in the GP; however, those changes were not statistically significant. The GS significantly increased their time in the 50-m competition style by 2.59%, and their isokinetic force production decreased by 14.47% (p < 0.05). The 6-week strength-training program performed with the power rack device in a pyramidal organization was more effective than a standard linear load organization in terms of producing improvements in the MDL; however, it did not produce significant improvements in performance. The use of a strength-training program with a pyramidal organization can be recommended for specific strength-training in young swimmers during a preparatory period. However, in our study, that program did not produce significant changes in 50-m crawl and main competition style performance

    Wind-aided flame spread under oblique forced flow

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    he wind-aided flame spread process along a solid fuel rod under oblique forced flow is analyzed in absence of gravity or when the forced flow dominates the gravity-induced flow. The transverse velocity is large enough to ensure that mixing of the fuel vapors and air occurs in a thin boundary layer surrounding the fuel rod and we can use the boundary layer approximation to describe the gas-phase chemical reaction and downwind flame spread process. A global, second-order, Arrhenius expression is employed to describe the gas-phase reaction, while the solid surface gasification reaction is modeled in terms of a constant pyrolysis temperature. The solid is heated by the hot gases convected from the flame by the axial component of the velocity in the direction of the flame spread. The solid will be considered thermally thick, assuming the thickness of the heated layer in the solid to be small compared with the rod radius. The analysis determines the flame spread velocity and the flow structure in the flame front region. The analysis also shows that flame spread is not possible at large flow velocities due to finite rate effects, while at low velocities the gas-phase reaction is diffusion-controlled. By including radiation losses from the surface a flame spread limit, at low velocities, is also found in the present analysis. The wind-aided flame spread process along a solid fuel rod under oblique forced flow is analyzed in absence of gravity or when the forced flow dominates the gravity-induced flow. The transverse velocity is large enough to ensure that mixing of the fuel vapors and air occurs in a thin boundary layer surrounding the fuel rod and we can use the boundary layer approximation to describe the gas-phase chemical reaction and downwind flame spread process. A global, second-order, Arrhenius expression is employed to describe the gas-phase reaction, while the solid surface gasification reaction is modeled in terms of a constant pyrolysis temperature. The solid is heated by the hot gases convected from the flame by the axial component of the velocity in the direction of the flame spread. The solid will be considered thermally thick, assuming the thickness of the heated layer in the solid to be small compared with the rod radius. The analysis determines the flame spread velocity and the flow structure in the flame front region. The analysis also shows that flame spread is not possible at large flow velocities due to finite rate effects, while at low velocities the gas-phase reaction is diffusion-controlled. By including radiation losses from the surface a flame spread limit, at low velocities, is also found in the present analysis

    Nature of the spin-glass phase at experimental length scales

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    We present a massive equilibrium simulation of the three-dimensional Ising spin glass at low temperatures. The Janus special-purpose computer has allowed us to equilibrate, using parallel tempering, L=32 lattices down to T=0.64 Tc. We demonstrate the relevance of equilibrium finite-size simulations to understand experimental non-equilibrium spin glasses in the thermodynamical limit by establishing a time-length dictionary. We conclude that non-equilibrium experiments performed on a time scale of one hour can be matched with equilibrium results on L=110 lattices. A detailed investigation of the probability distribution functions of the spin and link overlap, as well as of their correlation functions, shows that Replica Symmetry Breaking is the appropriate theoretical framework for the physically relevant length scales. Besides, we improve over existing methodologies to ensure equilibration in parallel tempering simulations.Comment: 48 pages, 19 postscript figures, 9 tables. Version accepted for publication in the Journal of Statistical Mechanic

    Characterization and analysis of thionin genes

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    The general designation of thionins has been proposed for a family of homologous proteins that have been isolated from different tissues in a wide range of plant taxa and have been variously named purothionins, viscotoxins, crambins, etc. (see Garcia-Olmedo et al., 1989). The possible involvement of thionins in plant defense was first suggested, on the basis of their in vitro toxicity to plant pathogens, by Fernandez de Caleya et al., (1972). Those observations had been prompted by earlier reports concerning the antimicrobial properties of these polypeptides (Stuart and Harris, 1942; Balls and Harris, 1944). Work on the thionins, which has been actively pursued over the past half-century, has been recently reviewed in detail (Garcia-Olmedo et al., 1989). For this reason, earlier work will only be partially summarized in the present chapter, which will focus on recent developments concerning thionin genes and their potential role in plant defense mechanisms

    Validation of metabolic syndrome using medical records in the SUN cohort

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    The objective of this study was to evaluate the validity of self reported criteria of Metabolic Syndrome (MS) in the SUN (Seguimiento Universidad de Navarra) cohort using their medical records as the gold standard. METHODS: We selected 336 participants and we obtained MS related data according to Adult Treatment Panel III (ATP III) and International Diabetes Federation (IDF). Then we compared information on the self reported diagnosis of MS and MS diagnosed in their medical records. We calculated the proportion of confirmed MS, the proportion of confirmed non-MS and the intraclass correlation coefficients for each component of the MS. RESULTS: From those 336 selected participants, we obtained sufficient data in 172 participants to confirm or reject MS using ATP III criteria. The proportion of confirmed MS was 91.2% (95% CI: 80.7- 97.1) and the proportion of confirmed non-MS was 92.2% (95% CI: 85.7-96.4) using ATP III criteria. The proportion of confirmed MS using IDF criteria was 100% (95% CI: 87.2-100) and the proportion of confirmed non-MS was 97.1% (95% CI: 85.1-99.9). Kappa Index was 0.82 in the group diagnosed by ATP III criteria and 0.97 in the group diagnosed by IDF criteria. Intraclass correlation coefficients for the different component of MS were: 0.93 (IC 95%:0.91- 0.95) for BMI; 0.96 (IC 95%: 0.93-0.98) for waist circumference; 0.75 (IC 95%: 0.66-0.82) for fasting glucose; 0.50 (IC 95%:0.35-0.639) for HDL cholesterol; 0.78 (IC 95%: 0.70-0.84) for triglycerides; 0.49 (IC 95%:0.34-0.61) for systolic blood pressure and 0.55 (IC 95%: 0.41-0.65) for diastolic blood pressure. CONCLUSIONS: Self-reported MS based on self reported components of the SM in a Spanish cohort of university graduates was sufficiently valid as to be used in epidemiological studies

    The thionins: a protein family that includes purothionins, viscotoxins and crambins

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    Almost half a century ago, a crystalline protein material was obtained from lipid extracts of wheat endosperm and designated "purothionin" (Trvpwo, wheat; 9 e i w v , sulphur) on account of its high sulphur content (Balls et al., 1942a,b). This material, which was thought to be the oxidized form of a powerful oxidation-reduction system, was found to have baetericidal and fungicidal properties (Stuart and Harris, 1942), to inhibit fermentation of wheat mashes (Balls and Harris, 1944), and to be toxic to laboratory animĂĄis (Coulson et al., 1942)
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