2,121 research outputs found

    Epithelioma of tongue

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    Controlling charge injection in organic field-effect transistors using self-assembled monolayers

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    We have studied charge injection across the metal/organic semiconductor interface in bottom-contact poly(3-hexylthiophene) (P3HT) field-effect transistors, with Au source and drain electrodes modified by self-assembled monolayers (SAMs) prior to active polymer deposition. By using the SAM to engineer the effective Au work function, we markedly affect the charge injection process. We systematically examine the contact resistivity and intrinsic channel mobility, and show that chemically increasing the injecting electrode work function significantly improves hole injection relative to untreated Au electrodes.Comment: 5 pages, 2 figures. Supplementary information available upon reques

    Gravity on Noncommutative D-Branes

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    The effective action for the low energy scattering of two gravitons with a D-brane in the presence of a constant antisytmetric BB field in bosonic string theory is calculated and the modification to the standard D-brane action to first order in α\alpha' is obtained.Comment: 18 pages, Latex file, accepted in Int. J. Mod. Phys.

    Omega 3, 6, 9 Enhanced Goat Meat (Omega-Chevon) from Flaxseed and Canola Fed Meat Goats

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    With growing obesity and cardiovascular disease concerns, the meat industry aims to reduce fat content in meat products. Currently Omega Fatty Acid (FA) enhanced beef and eggs are being marketed in the US, but Omega enhanced goat meat (Omega-Chevon) has not been developed. Meat goats were fed ground flaxseed and canola supplemented feed for 90 days. There were no palatability, weight, or health issues in meat goats fed canola and flaxseed supplemented feed. Chevon from goats fed canola and flaxseed had significant (

    Relativistic Acoustic Geometry

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    Sound wave propagation in a relativistic perfect fluid with a non-homogeneous isentropic flow is studied in terms of acoustic geometry. The sound wave equation turns out to be equivalent to the equation of motion for a massless scalar field propagating in a curved space-time geometry. The geometry is described by the acoustic metric tensor that depends locally on the equation of state and the four-velocity of the fluid. For a relativistic supersonic flow in curved space-time the ergosphere and acoustic horizon may be defined in a way analogous the non-relativistic case. A general-relativistic expression for the acoustic analog of surface gravity has been found.Comment: 14 pages, LaTe

    The massless gravitino and the AdS/CFT correspondence

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    We solve the Dirichlet boundary value problem for the massless gravitino on AdSd+1AdS_{d+1} space and compute the two-point function of the dual CFT supersymmetry currents using the AdSAdS/CFT correspondence principle. We find analogously to the spinor case that the boundary data for the massless (d+1)(d+1) dimensional bulk gravitino field consists of only a (d1)(d-1) dimensional gravitino.Comment: 10 pages, RevTe

    The M2/M5 BPS Partition Functions from Supergravity

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    In the framework of the AdS/CFT duality, we calculate the supersymmetric partition function of the superconformal field theories living in the world volume of either NN M2M2-branes or NN M5M5-branes. We used the dual supergravity partition function in a saddle point approximation over supersymmetric Black Holes. Since our BHs are written in asymptotically global AdSd+1AdS_{d+1} co-ordinates, the dual SCFTs are in RxSdR x S^{d} for d=2,5d=2,5. The resulting partition function shows phase transitions, constraints on the phase space and allowed us to identify unstable BPS Black hole in the AdSAdS phase. These configurations should correspond to unstable configurations in the dual theory. We also report an intriguing relation between the most general Witten Index, computed in the above theories, and our BPS partition functions.Comment: 9 pages, 2 columns, 4 figures, revtex, typos corrected, reference adde

    Symmetry and Integrability of Non-Singlet Sectors in Matrix Quantum Mechanics

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    We study the non-singlet sectors of matrix quantum mechanics (MQM) through an operator algebra which generates the spectrum. The algebra is a nonlinear extension of the W_\infty algebra where the nonlinearity comes from the angular part of the matrix which can not be neglected in the non-singlet sector. The algebra contains an infinite set of commuting generators which can be regarded as the conserved currents of MQM. We derive the spectrum and the eigenfunctions of these conserved quantities by a group theoretical method. An interesting feature of the spectrum of these charges in the non-singlet sectors is that they are identical to those of the singlet sector except for the multiplicities. We also derive the explicit form of these commuting charges in terms of the eigenvalues of the matrix and show that the interaction terms which are typical in Calogero-Sutherland system appear. Finally we discuss the bosonization and rewrite the commuting charges in terms of a free boson together with a finite number of extra degrees of freedom for the non-singlet sectors.Comment: 34 pages, 4 figure

    Trans-Planckian Physics and the Spectrum of Fluctuations in a Bouncing Universe

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    In this paper, we calculate the spectrum of scalar field fluctuations in a bouncing, asymptotically flat Universe, and investigate the dependence of the result on changes in the physics on length scales shorter than the Planck length which are introduced via modifications of the dispersion relation. In this model, there are no ambiguities concerning the choice of the initial vacuum state. We study an example in which the final spectrum of fluctuations depends sensitively on the modifications of the dispersion relation without needing to invoke complex frequencies. Changes in the amplitude and in the spectral index are possible, in addition to modulations of the spectrum. This strengthens the conclusions of previous work in which the spectrum of cosmological perturbations in expanding inflationary cosmologies was studied, and it was found that, for dispersion relations for which the evolution is not adiabatic, the spectrum changes from the standard prediction of scale-invariance.Comment: 10 pages, 6 figures, RevTeX4. Analytical determination of the spectrum, corrected some typos, conclusions unchange

    Fermionic microstates within Painlev\'e-Gullstrand black hole

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    We consider the quantum vacuum of fermionic field in the presence of a black-hole background as a possible candidate for the stabilized black hole. The stable vacuum state (as well as thermal equilibrium states with arbitrary temperature) can exist if we use the Painlev\'e-Gullstrand description of the black hole, and the superluminal dispersion of the particle spectrum at high energy, which is introduced in the free-falling frame. Such choice is inspired by the analogy between the quantum vacuum and the ground state of quantum liquid, in which the event horizon for the low-energy fermionic quasiparticles also can arise. The quantum vacuum is characterized by the Fermi surface, which appears behind the event horizon. We do not consider the back reaction, and thus there is no guarantee that the stable black hole exists. But if it does exist, the Fermi surface behind the horizon would be the necessary attribute of its vacuum state. We also consider exact discrete spectrum of fermions inside the horizon which allows us to discuss the problem of fermion zero modes.Comment: LaTeX, 20 pages, 2 figure
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