896 research outputs found
The ergogenic effect of beta-alanine combined with sodium bicarbonate on high-intensity swimming performance
We investigated the effect of beta-alanine (BA) alone (study A) and in combination with sodium bicarbonate (SB) (study B) on 100- and 200-m swimming performance. In study A, 16 swimmers were assigned to receive either BA (3.2 g·day−1 for 1 week and 6.4 g·day−1 for 4 weeks) or placebo (PL; dextrose). At baseline and after 5 weeks of supplementation, 100- and 200-m races were completed. In study B, 14 were assigned to receive either BA (3.2 g·day−1 for 1 week and 6.4 g·day−1 for 3 weeks) or PL. Time trials were performed once before and twice after supplementation (with PL and SB), in a crossover fashion, providing 4 conditions: PL-PL, PL-SB, BA-PL, and BA-SB. In study A, BA supplementation improved 100- and 200-m time-trial performance by 2.1% (p = 0.029) and 2.0% (p = 0.0008), respectively. In study B, 200-m time-trial performance improved in all conditions, compared with presupplementation, except the PL-PL condition (PL-SB, +2.3%; BA-PL, +1.5%; BA-SB, +2.13% (p < 0.05)). BA-SB was not different from BA-PL (p = 0.21), but the probability of a positive effect was 78.5%. In the 100-m time-trial, only a within-group effect for SB was observed in the PL-SB (p = 0.022) and BA-SB (p = 0.051) conditions. However, 6 of 7 athletes swam faster after BA supplementation. The probability of BA having a positive effect was 65.2%; when SB was added to BA, the probability was 71.8%. BA and SB supplementation improved 100- and 200-m swimming performance. The coingestion of BA and SB induced a further nonsignificant improvement in performance
Algebraic cubature on polygonal elements with a circular edge
We compute low-cardinality algebraic cubature formulas on convex or concave polygonal elements with a circular edge, by subdivision into circular quadrangles, blending formulas via subperiodic trigonometric Gaussian quadrature and final compression via Caratheodory\u2013Tchakaloff subsampling of discrete measures. We also discuss applications to the VEM (Virtual Element Method) in computational mechanics problems
Ocupação das matas ciliares pelos empreendimentos do turismo de pesca no rio Miranda, Pantanal, Brasil.
A localização de Salobra e a região ribeirinha da cidade de Miranda formam o universo de pesquisa deste estudo. Essa região situa-se no Pantanal de Miranda, na parte oeste do Estado de Mato Grosso do Sul. Apresenta o levantamento dos estabelecimentos turÃsticos na região, entre os anos de 1960 ao final da década de 90. O crescimento dos empreendimentos de turismo, particularmente os de pesca esportiva, contribuÃram para a mudança do perfil socioeconômico local, com o surgimento de uma maior oferta de empregos e abertura de novos campos profissionais, destacando-se o de piloteiro. Na área ambiental, entretanto, pode-se observar o surgimento de uma paisagem modificada pelo crescimento explosivo de ranchos de pesca, à s margens do rio Miranda, em área de preservação permanente. A instalação e operacionalidade dessas edificações levaram à degradação ambiental promovida pela derrubada de vegetação ribeirinha, com conseqüente erosão das área marginais ao rio, à produção de resÃduos sólidos domésticos depositados a céu aberto, bem como ao despejo de efluentes na calha fluvial do Miranda.bitstream/item/37292/1/BP64.pd
Low-Temperature Rapid Synthesis and Superconductivity of Fe-Based Oxypnictide Superconductors
we were able to develop a novel method to synthesize Fe-based oxypnictide
superconductors. By using LnAs and FeO as the starting materials and a
ball-milling process prior to solid-state sintering, Tc as high as 50.7 K was
obtained with the sample of Sm 0.85Nd0.15FeAsO0.85F0.15 prepared by sintering
at temperatures as low as 1173 K for times as short as 20 min.Comment: 2 pages,2 figures, 1 tabl
State update algorithm for associative elastic-plastic pressure-insensitive materials by incremental energy minimization
This work presents a new state update algorithm for small-strain associative elastic-plastic
constitutive models, treating in a unified manner a wide class of deviatoric yield functions with linear or
nonlinear strain-hardening. The algorithm is based on an incremental energy minimization approach, in the
framework of generalized standard materials with convex free energy and dissipation potential. An efficient
method for the computation of the latter, its gradient and its Hessian is provided, using Haigh-Westergaard
stress invariants. Numerical results on a single material point loading history and finite element simulations are
reported to prove the effectiveness and the versatility of the method. Its merit turns out to be complementary
to the classical return map strategy, because no convergence difficulties arise if the stress is close to high
curvature points of the yield surface
A combined experimental and computational study of the pressure dependence of the vibrational spectrum of solid picene C_22H_14
We present high-quality optical data and density functional perturbation
theory calculations for the vibrational spectrum of solid picene
(CH) under pressure up to 8 GPa. First-principles calculations
reproduce with a remarkable accuracy the pressure effects on both frequency and
intensities of the phonon peaks experimentally observed . Through a detailed
analysis of the phonon eigenvectors, We use the projection on molecular
eigenmodes to unambiguously fit the experimental spectra, resolving complicated
spectral structures, in a system with hundreds of phonon modes. With these
projections, we can also quantify the loss of molecular character under
pressure. Our results indicate that picene, despite a \sim 20 % compression of
the unit cell, remains substantially a molecular solid up to 8 GPa, with phonon
modes displaying a smooth and uniform hardening with pressure. The Grueneisen
parameter of the 1380 cm^{-1} a_1 Raman peak () is much lower
than the effective value () due to K doping. This is an
indication that the phonon softening in K doped samples is mainly due to charge
transfer and electron-phonon coupling.Comment: Replaced with final version (PRB
Vibrational spectrum of solid picene (C_22H_14)
Recently, Mitsuhashi et al., have observed superconductivity with transition
temperature up to 18 K in potassium doped picene (C22H14), a polycyclic
aromatic hydrocarbon compound [Nature 464 (2010) 76]. Theoretical analysis
indicate the importance of electron-phonon coupling in the superconducting
mechanisms of these systems, with different emphasis on inter- and
intra-molecular vibrations, depending on the approximations used. Here we
present a combined experimental and ab-initio study of the Raman and infrared
spectrum of undoped solid picene, which allows us to unanbiguously assign the
vibrational modes. This combined study enables the identification of the modes
which couple strongly to electrons and hence can play an important role in the
superconducting properties of the doped samples
Focusing properties of linear undulators
This paper investigates the focusing properties of linear magnetic undulators, i.e., devices characterized by weak defocusing properties in the horizontal (wiggling) plane and strongly focusing in the vertical plane. The problem of identifying the conditions that ensure the existence of the electron beam eigenstates in the undulator lattice for a given working point of electron beam energy E_{b} and resonant wavelength λ_{r} is studied. For any given undulator lattice, a bandlike structure is identified defining regions in the (E_{b},λ_{r}) plane where no periodic matching condition can be found, i.e., it is not possible to transport the electron beam so that optical functions are periodic at lattice boundaries. Some specific cases are discussed for the SPARC FEL undulator
A Framework for Automating Security Assessments with Deductive Reasoning
Proper testing of hardware and software infrastructure and applications has become mandatory. To this purpose, security researchers and software companies have released a plethora of domain specific tools, libraries and frameworks that assist human operators (penetration testers, red teamers, bug hunters) in finding and exploiting specific vulnerabilities, and orchestrating the activities of a security assessment. Most tools also require minor reconfigurations in order to operate properly with isomorphic systems, characterized by the same exploitation path even in presence of different configurations. In this paper we present a human-assisted framework that tries to overcome the aforementioned limitations. Our proposal is based on a Prolog-based expert system with facts and deductive rules that allow to infer new facts from existing ones. Rules are bound to actions whose results are fed back into the knowledge base as further facts. In this way, a security assessment is treated like a theorem that has to be proven. We have built an initial prototype and evaluated it in different security assessments of increasing complexity (jeopardy and boot-to-root machines). Our preliminary results show that the proposed approach can address the following challenges; (a) reaching non-standard goals (which would be missed by most tools and frameworks); (b) solving isomorphic systems without the need for reconfiguration; (c) identifying vulnerabilities from chained weaknesses and exposures
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