484 research outputs found

    11-Dimensional Supergravity Compactified on Calabi-Yau Threefolds

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    We consider generic features of eleven dimensional supergravity compactified down to five dimensions on an arbitrary Calabi-Yau threefold.Comment: TeX, harvmac, 8 pg

    The Elementary Particles as Quantum Knots in Electroweak Theory

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    We explore a knot model of the elementary particles that is compatible with electroweak physics. The knots are quantized and their kinematic states are labelled by Dmm′jD^j_{mm'}, irreducible representations of SUq(2)SU_q(2), where j = N/2, m = w/2, m' = (r+1)/2 and (N,w,r) designate respectively the number of crossings, the writhe, and the rotation of the knot. The knot quantum numbers (N,w,r) are related to the standard isotopic spin quantum numbers (t,t3,t0)(t,t_3,t_0) by (t=N/6,t3=−w/6,t0=−(r+1)/6)(t=N/6,t_3=-w/6,t_0=-(r+1)/6), where t0t_0 is the hypercharge. In this model the elementary fermions are low lying states of the quantum trefoil (N=3) and the gauge bosons are ditrefoils (N=6). The fermionic knots interact by the emission and absorption of bosonic knots. In this framework we have explored a slightly modified standard electroweak Lagrangian with a slightly modified gauge group which agrees closely but not entirely with standard electroweak theory.Comment: 29 pages; LaTex fil

    Effect of Reprocessing and Excipient Characteristics on Ibuprofen Tablet Properties

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    Purpose: To determine excipient and ibuprofen:excipient mixture sensitivity to reprocessing produced by either direct compression or wet granulation.Methods: The effect of excipient type, technology and reprocessing on flow, compressibility and compactibility was assessed using and 8x2x2 factorial design. Design Expert® v.8.01 software was employed for data analysis. Pure excipients were processed by direct compression, while the ibuprofen:excipient mixtures were processed by wet granulation. Once compacts were produced, they were milled and reprocessed using the same technologies, respectively. Excipient properties such as particle size, porosity and densities were also evaluated.Results: For most excipients, reprocessing caused a 20 – 50 % decrease in particle size and 5 – 80 % reduction in porosity, but increased compactibility (10 – 50 %). Flow decreased (30 – 50 %) only for highly densified excipients such as calcium carbonate and calcium diphosphate.Conclusion: Microcrystalline cellulose and sorbitol are the excipients with the best tableting properties when reprocessing is conducted via wet granulation and direct compression platforms, respectively.Keywords: Reprocessing, Excipient, Microcrystalline Cellulose, Sorbitol Direct Compression, Wet Granulation, Ibuprofe

    Masses and Interactions of q-Fermionic Knots

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    The q-electroweak theory suggests a description of elementary particles as solitons labelled by the irreducible representations of SU_q(2). Since knots may also be labelled by the irreducible representations of SU_q(2), we study a model of elementary particles based on a one-to-one correspondence between the four families of Fermions (leptons, neutrinos, (-1/3) quarks, (2/3) quarks) and the four simplest knots (trefoils). In this model the three particles of each family are identified with the ground and first two excited states of their common trefoil. Guided by the standard electroweak theory we calculate conditions restricting the masses of the fermions and the interactions between them. In its present form the model predicts a fourth generation of fermions as well as a neutrino spectrum. The same model with q almost equal to 1 is compatible with the Kobayashi-Maskawa matrix. Depending on the test of these predictions, the model may be refined.Comment: 40 pages, 2 figures, latex forma

    Knots and Preons

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    It is shown that the four trefoil solitons that are described by the irreducible representations D^{3/2}_{mm'} of the quantum algebra SL_q(2) (and that may be identified with the four families of elementary fermions (e,\mu,\tau;\nu_e\nu_\mu\nu_\tau;d,s,b;u,c,t) may be built out of three preons, chosen from two charged preons with charges (1/3,-1/3) and two neutral preons. These preons are Lorentz spinors and are described by the D^{1/2}_{mm'} representation of SL_q(2). There are also four bosonic preons described by the D^1_{mm'} and D^0_{00} representations of SL_q(2). The knotted standard theory may be replicated at the preon level and the conjectured particles are in principle indirectly observable.Comment: LaTex document; 12 pages; 4 table

    On the critical point structure of eigenfunctions belonging to the first nonzero eigenvalue of a genus two closed hyperbolic surface

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    We develop a method based on spectral graph theory to approximate the eigenvalues and eigenfunctions of the Laplace-Beltrami operator of a compact riemannian manifold -- The method is applied to a closed hyperbolic surface of genus two -- The results obtained agree with the ones obtained by other authors by different methods, and they serve as experimental evidence supporting the conjectured fact that the generic eigenfunctions belonging to the first nonzero eigenvalue of a closed hyperbolic surface of arbitrary genus are Morse functions having the least possible total number of critical points among all Morse functions admitted by such manifold
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