5,355 research outputs found

    The literature of low g propellant behavior

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    Annotated bibliography on low-g liquid propellant behavio

    Tip Splittings and Phase Transitions in the Dielectric Breakdown Model: Mapping to the DLA Model

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    We show that the fractal growth described by the dielectric breakdown model exhibits a phase transition in the multifractal spectrum of the growth measure. The transition takes place because the tip-splitting of branches forms a fixed angle. This angle is eta dependent but it can be rescaled onto an ``effectively'' universal angle of the DLA branching process. We derive an analytic rescaling relation which is in agreement with numerical simulations. The dimension of the clusters decreases linearly with the angle and the growth becomes non-fractal at an angle close to 74 degrees (which corresponds to eta= 4.0 +- 0.3).Comment: 4 pages, REVTex, 3 figure

    Developing the evidence base for adult social care practice: The NIHR School for Social Care Research

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    In a foreword to 'Shaping the Future of Care Together', Prime Minister Gordon Brown says that a care and support system reflecting the needs of our times and meeting our rising aspirations is achievable, but 'only if we are prepared to rise to the challenge of radical reform'. A number of initiatives will be needed to meet the challenge of improving social care for the growing older population. Before the unveiling of the green paper, The National Institute for Health Research (NIHR) announced that it has provided 15m pounds over a five-year period to establish the NIHR School for Social Care Research. The School's primary aim is to conduct or commission research that will help to improve adult social care practice in England. The School is seeking ideas for research topics, outline proposals for new studies and expert advice in developing research methods

    The Effects of Olympic Weightlifting Derivatives on Muay Thai Roundhouse Kicking Performance

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    The purpose of this study was to identify performance measures in roundhouse striking, by the implementation of Olympic Weightlifting Derivatives (OWLD) with Muay Thai fighters. Forty male subjects were recruited, with twenty male subjects placed in the experimental group (EG)and twenty male subjects in the control group (CG) and were randomly assigned to their groups. Mean 26 years 3 (± 3.2), weight and height 82.4 kg (± 12.2), and 180.7cm (± 3). Pre- and post-intervention and control group testing included roundhouse strike impact power, measured using the PowerKubeTM, a dynamometer that identifies the impact power used to produce striking potential. Countermovement jumps were recorded using a single PASCO force platform one axis PS2141. The EG subjects were prescribed an eight-week training programme that was carried out prior to their sparring with twenty minutes rest to recover. The control group were instructed to carry out traditional training that involved the same volume of sparring, cardiovascular fitness, and circuit training as the EG. Within-group post test results showed the EG and CG group demonstrated significantly different results in RHK performance (p ≀ 0.01); however, no significant differences were observed between groups. Results in the countermovement jump were, however, highly significant (p ≀ 0.01) in the EG (within group), but not significant in the CG (p ≄ 0.05); again, no significant differences were observed between groups. Meaningful differences were seen in the EG with a 7.41% increase in roundhouse kicking performance and 7.54% in countermovement jump height, compared to the CG that elicited negligible differences of only 1.56% in the roundhouse kicking performance and 0.33% in countermovement jumper, demonstrating OWLD would improve the performance of the Muay Thai fighter

    Anomalies in the Entanglement Properties of the Square Lattice Heisenberg Model

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    We compute the bipartite entanglement properties of the spin-half square-lattice Heisenberg model by a variety of numerical techniques that include valence bond quantum Monte Carlo (QMC), stochastic series expansion QMC, high temperature series expansions and zero temperature coupling constant expansions around the Ising limit. We find that the area law is always satisfied, but in addition to the entanglement entropy per unit boundary length, there are other terms that depend logarithmically on the subregion size, arising from broken symmetry in the bulk and from the existence of corners at the boundary. We find that the numerical results are anomalous in several ways. First, the bulk term arising from broken symmetry deviates from an exact calculation that can be done for a mean-field Neel state. Second, the corner logs do not agree with the known results for non-interacting Boson modes. And, third, even the finite temperature mutual information shows an anomalous behavior as T goes to zero, suggesting that T->0 and L->infinity limits do not commute. These calculations show that entanglement entropy demonstrates a very rich behavior in d>1, which deserves further attention.Comment: 12 pages, 7 figures, 2 tables. Numerical values in Table I correcte

    Exact Multifractal Spectra for Arbitrary Laplacian Random Walks

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    Iterated conformal mappings are used to obtain exact multifractal spectra of the harmonic measure for arbitrary Laplacian random walks in two dimensions. Separate spectra are found to describe scaling of the growth measure in time, of the measure near the growth tip, and of the measure away from the growth tip. The spectra away from the tip coincide with those of conformally invariant equilibrium systems with arbitrary central charge c≀1c\leq 1, with cc related to the particular walk chosen, while the scaling in time and near the tip cannot be obtained from the equilibrium properties.Comment: 4 pages, 3 figures; references added, minor correction

    Characteristics of Subcooled Liquid Methane During Passage Through a Spray-Bar Joule-Thompson Thermodynamic Vent System

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    NASA s Marshall Space Flight Center (MSFC) conducted liquid methane (LCH4) testing in November 2006 using the multipurpose hydrogen test bed (MHTB) outfitted with a spray-bar thermodynamic vent system (TVS). The basic objective was to identify any unusual or unique thermodynamic characteristics associated with subcooled LCH4 that should be considered in the design of space-based TVSs. Thirteen days of testing were performed with total tank heat loads ranging from 720 W to 420 W at a fill level of approximately 90%. During an updated evaluation of the data, it was noted that as the fluid passed through the Joule Thompson expansion, thermodynamic conditions consistent with the pervasive presence of metastability were indicated. This paper describes the observed thermodynamic conditions that correspond with metastability and effects on TVS performance

    Simulating adiabatic evolution of gapped spin systems

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    We show that adiabatic evolution of a low-dimensional lattice of quantum spins with a spectral gap can be simulated efficiently. In particular, we show that as long as the spectral gap \Delta E between the ground state and the first excited state is any constant independent of n, the total number of spins, then the ground-state expectation values of local operators, such as correlation functions, can be computed using polynomial space and time resources. Our results also imply that the local ground-state properties of any two spin models in the same quantum phase can be efficiently obtained from each other. A consequence of these results is that adiabatic quantum algorithms can be simulated efficiently if the spectral gap doesn't scale with n. The simulation method we describe takes place in the Heisenberg picture and does not make use of the finitely correlated state/matrix product state formalism.Comment: 13 pages, 2 figures, minor change

    Orthonormal Polynomials on the Unit Circle and Spatially Discrete Painlev\'e II Equation

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    We consider the polynomials ϕn(z)=Îșn(zn+bn−1zn−1+>...)\phi_n(z)= \kappa_n (z^n+ b_{n-1} z^{n-1}+ >...) orthonormal with respect to the weight exp⁥(λ(z+1/z))dz/2πiz\exp(\sqrt{\lambda} (z+ 1/z)) dz/2 \pi i z on the unit circle in the complex plane. The leading coefficient Îșn\kappa_n is found to satisfy a difference-differential (spatially discrete) equation which is further proved to approach a third order differential equation by double scaling. The third order differential equation is equivalent to the Painlev\'e II equation. The leading coefficient and second leading coefficient of ϕn(z)\phi_n(z) can be expressed asymptotically in terms of the Painlev\'e II function.Comment: 16 page

    Profiling The Physiological Parameters of Boxers in The Parachute Regiment. ‘Every Man an Emperor’

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    This study aimed to collect and identify the physiological parameters that are required to produce winning performances in an army boxing competition. Army boxing competitions are sanctioned and governed by ‘England Boxing’ and consist of three rounds of two minutes with one-minute restorative periods. The Parachute Regiment are an elite infantry fighting force within the British military, with a continued success in the inter-army boxing championships. 22 male participants were recruited (mean ± SD age 28 ± 2 years, stature 178 ± 8.1cm, body mass 79 ± 7.1 kg, BMI 24.9 ±2.5).Body fat %. V̇O₂max, lower limb power, and 1RM max strength test protocols for back squat and bench press were performed. Additionally, impact punch power measured from rear hand cross strikes, and punching velocities were measured using a linear positional transducer. Countermovement (CMJ) and repetitive (n=10) jump data were collected using a jump mat. The physiological parameters in mean scores; body composition showed body fat 11.8±8.1%: CMJ height 35.5±5cm: Repetitive jump 28.5±5.6cm: Wingate peak power (body mass to power ratio) 11.5±1.6W/kg: Wingate average power, 8.1±1.4W/kg: V̇O₂max 53±4.8 ml.kg⁻Âč.min⁻Âč: Back squat (body mass to weight lifted ratio) 1.95±0.2kg: Bench press 1.1±0.1kg/BW: Rear cross strike velocity 8.47±0.8m/s: Impact power 15227±2250W. Significant relationships were observed between anthropometric data and power, strike velocity and V̇O₂max in addition to relationships being evident between some strength and power variables. by the participants in this study. Although punch impact power is an essential performance indicator in boxing, other physiological factors, such as lower limb power and strength have been demonstrated to attribute to the continued winning performances by 3PARA boxing team
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