11,220 research outputs found

    Effects of whey products on performance of weaned pigs

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    Three trials were conducted utilizing 458 pigs with an average age of 21 days to study the effects of adding whole whey, or partially delactosed whey from two sources in the diet of weaned pigs on growth, feed intake, and feed efficiency. Additionally, the optimum length of time to feed whole whey and the relationship of age at weaning and addition of whey to the diet were studied. The addition of whey to the diets increased performance of the pigs by 2 to 3 pounds at 8 weeks of age. Pigs fed 20% whole whey diets for 2 weeks performed similarly as those fed 20% whole whey for 5 weeks. No differer1ces were observed between pigs fed whole whey and partially delactosed whey diets. Partially delactosed whey from two different sources produced similar pig performance. Pigs weaned at 3 and 5 weeks performed similarly and out-performed those weaned at 2 weeks. Pigs fed 20% whole whey (weaned at 2, 3, 4, or 5 weeks) outperformed pigs fed the control diet.; Swine Day, Manhattan, KS, November 11, 198

    Non-Abelian pp-waves in D=4 supergravity theories

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    The non-Abelian plane waves, first found in flat spacetime by Coleman and subsequently generalized to give pp-waves in Einstein-Yang-Mills theory, are shown to be 1/2 supersymmetric solutions of a wide variety of N=1 supergravity theories coupled to scalar and vector multiplets, including the theory of SU(2) Yang-Mills coupled to an axion \sigma and dilaton \phi recently obtained as the reduction to four-dimensions of the six-dimensional Salam-Sezgin model. In this latter case they provide the most general supersymmetric solution. Passing to the Riemannian formulation of this theory we show that the most general supersymmetric solution may be constructed starting from a self-dual Yang-Mills connection on a self-dual metric and solving a Poisson equation for e^\phi. We also present the generalization of these solutions to non-Abelian AdS pp-waves which allow a negative cosmological constant and preserve 1/4 of supersymmetry.Comment: Latex, 1+12 page

    A multi-layer active elastic metamaterial with tuneable and simultaneously negative mass and stiffness

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    All conventional acoustic/elastic media are restricted to possess positive constants for their constitutive parameters (density and modulus). Metamaterials provide an approach through which this restriction can be broken. By making these parameters negative and/or tuneable a broader range of properties becomes possible. This paper describes the first experimental implementation of an acoustic/elastic metamaterial in which the material parameters can be both simultaneously negative in a finite frequency band and the magnitude of the parameters independently tuneable on demand. The design is an active metamaterial (meta-mechanical-system) which is realized by directly applying feedback control forces to each layer within the metamaterial. The ability to tune the magnitude of the negative parameters has important implications for the use of a standard design that can be tuned to a particular application, or one which can adapt to a changing performance requirement. The implementation of the design is relatively large scale and low frequency, but the unit-cell length is significantly smaller than the wavelength in the double negative band. Importantly, assuming appropriate control hardware is available, the design can be both reduced in scaled and expanded to greater degrees of freedom. © 2014 IOP Publishing Ltd

    The general form of supersymmetric solutions of N=(1,0) U(1) and SU(2) gauged supergravities in six dimensions

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    We obtain necessary and sufficient conditions for a supersymmetric field configuration in the N=(1,0) U(1) or SU(2) gauged supergravities in six dimensions, and impose the field equations on this general ansatz. It is found that any supersymmetric solution is associated to an SU(2)⋉R4SU(2)\ltimes \mathbb{R}^4 structure. The structure is characterized by a null Killing vector which induces a natural 2+4 split of the six dimensional spacetime. A suitable combination of the field equations implies that the scalar curvature of the four dimensional Riemannian part, referred to as the base, obeys a second order differential equation. Bosonic fluxes introduce torsion terms that deform the SU(2)⋉R4SU(2)\ltimes\mathbb{R}^4 structure away from a covariantly constant one. The most general structure can be classified in terms of its intrinsic torsion. For a large class of solutions the gauge field strengths admit a simple geometrical interpretation: in the U(1) theory the base is K\"{a}hler, and the gauge field strength is the Ricci form; in the SU(2) theory, the gauge field strengths are identified with the curvatures of the left hand spin bundle of the base. We employ our general ansatz to construct new supersymmetric solutions; we show that the U(1) theory admits a symmetric Cahen-Wallach4×S2_4\times S^2 solution together with a compactifying pp-wave. The SU(2) theory admits a black string, whose near horizon limit is AdS3×S3AdS_3\times S_3. We also obtain the Yang-Mills analogue of the Salam-Sezgin solution of the U(1) theory, namely R1,2×S3R^{1,2}\times S^3, where the S3S^3 is supported by a sphaleron. Finally we obtain the additional constraints implied by enhanced supersymmetry, and discuss Penrose limits in the theories.Comment: 1+29 pages, late

    Variant N=(1,1) Supergravity and (Minkowski)_4 x S^2 Vacua

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    We construct the fermionic sector and supersymmetry transformation rules of a variant N=(1,1) supergravity theory obtained by generalized Kaluza-Klein reduction from seven dimensions. We show that this model admits both (Minkowski)_4 x S^2 and (Minkowski)_3 x S^3 vacua. We perform a consistent Kaluza-Klein reduction on S^2 and obtain D=4, N=2 supergravity coupled to a vector multiplet, which can be consistently truncated to give rise to D=4, N=1 supergravity with a chiral multiplet.Comment: Latex, 17 pages. Version appearing in Classical and Quantum Gravit

    Observation of intermittency in wave turbulence

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    We report the observation of intermittency in gravity-capillary wave turbulence on the surface of mercury. We measure the temporal fluctuations of surface wave amplitude at a given location. We show that the shape of the probability density function of the local slope increments of the surface waves strongly changes across the time scales. The related structure functions and the flatness are found to be power laws of the time scale on more than one decade. The exponents of these power laws increase nonlinearly with the order of the structure function. All these observations show the intermittent nature of the increments of the local slope in wave turbulence. We discuss the possible origin of this intermittency.Comment: new version to Phys. Rev. Let

    Investigation of passive flow control techniques to enhance the stall characteristics of a microlight aircraft

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    This report investigates the enhancement of aerodynamic stall characteristics of a Skyranger microlight aircraft by the use of passive flow control techniques, namely vortex generators and turbulators. Each flow control device is designed and scaled to application conditions. Force balance measurements and surface oil flow visualisation are carried out on a half-model of the microlight to further investigate the nature of the flow on the aircraft with and without the flow control devices. The results indicate a clear advantage to the use of turbulators compared with vortex generators. Turbulators increased the maximum lift coefficient by 2.8%, delayed the onset of stall by increasing the critical angle by 17.6% and reduced the drag penalty at both lower (pre-stall) and higher angles of attack by 8% compared to vortex generators. With vortex generators applied, the results indicated a delayed stall with an increase in the critical angle by 2% and a reduced drag penalty at higher angles of attack

    Drag Reduction by Polymers in Wall Bounded Turbulence

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    We address the mechanism of drag reduction by polymers in turbulent wall bounded flows. On the basis of the equations of fluid mechanics we present a quantitative derivation of the "maximum drag reduction (MDR) asymptote" which is the maximum drag reduction attained by polymers. Based on Newtonian information only we prove the existence of drag reduction, and with one experimental parameter we reach a quantitative agreement with the experimental measurements.Comment: 4 pages, 1 fig., included, PRL, submitte

    Partition Functions, the Bekenstein Bound and Temperature Inversion in Anti-de Sitter Space and its Conformal Boundary

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    We reformulate the Bekenstein bound as the requirement of positivity of the Helmholtz free energy at the minimum value of the function L=E- S/(2\pi R), where R is some measure of the size of the system. The minimum of L occurs at the temperature T=1/(2\pi R). In the case of n-dimensional anti-de Sitter spacetime, the rather poorly defined size R acquires a precise definition in terms of the AdS radius l, with R=l/(n-2). We previously found that the Bekenstein bound holds for all known black holes in AdS. However, in this paper we show that the Bekenstein bound is not generally valid for free quantum fields in AdS, even if one includes the Casimir energy. Some other aspects of thermodynamics in anti-de Sitter spacetime are briefly touched upon.Comment: Latex, 32 page
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