1,776 research outputs found

    The Effect of Various Experimental Factors and Adrenocorticotrophic Hormones on the Spreading Effect of Hyaluronidases

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    Thesis (M.A.)--Boston UniversityInvestigations were performed to clarify further the fundamental interrelationships between adrenocorticotrophic hormones fram the pituitary and from the placenta, and adrenal cortical hormones, with specific reference to hyaluronidasehyaluronic acid metabolism. A refinement of assay procedures in hyaluronidase studies in the experimental mouse and rat, has been made to obtain uniformly reproducible data and to facilitate a more meaningful interpretation of results. Animal studies have necessitated the experimental establishment and maintenance of rat and mouse colonies. The minimization of many biological variables has resulted. In the course of the maintenance and care of hypophysectomized and adrenalectomized rats, the effects of long-term hypophysectomy and adrenalectomy have been observed. It is noteworthy that exceptional survival and good health have been in evidence in the absence of substitution hormonal therapy. [TRUNCATED

    Topological Phases: An Expedition off Lattice

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    Motivated by the goal to give the simplest possible microscopic foundation for a broad class of topological phases, we study quantum mechanical lattice models where the topology of the lattice is one of the dynamical variables. However, a fluctuating geometry can remove the separation between the system size and the range of local interactions, which is important for topological protection and ultimately the stability of a topological phase. In particular, it can open the door to a pathology, which has been studied in the context of quantum gravity and goes by the name of `baby universe', Here we discuss three distinct approaches to suppressing these pathological fluctuations. We complement this discussion by applying Cheeger's theory relating the geometry of manifolds to their vibrational modes to study the spectra of Hamiltonians. In particular, we present a detailed study of the statistical properties of loop gas and string net models on fluctuating lattices, both analytically and numerically.Comment: 38 pages, 22 figure

    Fundamental Bound on Epidemic Overshoot in the SIR Model

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    We derive an exact upper bound on the epidemic overshoot for the Kermack-McKendrick SIR model. This maximal overshoot value of 0.2984... occurs at R0∗R_0^* = 2.151... Using the general analysis framework presented within, we then consider more complex SIR models, such as those that incorporate vaccination or contact heterogeneity. We analyze models that consider vaccinations and show that the presence of vaccinated individuals decreases the maximum possible overshoot. For epidemics where the contact structure is given by a network, we numerically find that increased contact heterogeneity lowers the maximal overshoot value and weakens the dependency of overshoot on transmission.Comment: 11 pages, 6 figures + 2 supplemental figure

    Topological Quantum Computing with Only One Mobile Quasiparticle

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    In a topological quantum computer, universal quantum computation is performed by dragging quasiparticle excitations of certain two dimensional systems around each other to form braids of their world lines in 2+1 dimensional space-time. In this paper we show that any such quantum computation that can be done by braiding nn identical quasiparticles can also be done by moving a single quasiparticle around n-1 other identical quasiparticles whose positions remain fixed.Comment: 4 pages, 5 figure

    A 3% Determination of H0H_0 at Intermediate Redshifts

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    Recent determinations of the Hubble constant, H_0, at extremely low and very high redshifts based on the cosmic distance ladder (grounded with trigonometric parallaxes) and a cosmological model (applied to Planck 2013 data) respectively, are revealing an intriguing discrepancy (nearly 9% or 2.4sigma) that is challenging astronomers and theoretical cosmologists. In order to shed some light on this problem, here we discuss a new determination of H_0 at intermediate redshifts (z ~ 1), using the following four cosmic probes: (i) measurements of the angular diameter distances (ADD) for galaxy clusters based on the combination of Sunyaev-Zeldovich effect and X-ray data (0.14 < z < 0.89$), (ii) the inferred ages of old high redshift galaxies (OHRG) (0.62 < z < 1.70), (iii) measurements of the Hubble parameter H(z) (0.1 < z < 1.8), and (iv) the baryon acoustic oscillation (BAO) signature (z=0.35). In our analysis, assuming a flat LCDM cosmology and considering statistical plus systematic errors we obtain H_0 = 74.1^{+2.2}_{-2.2} km/s.Mpc (1sigma) which is a 3% determination of the Hubble constant at intermediate redshifts. We stress that each individual test adopted here has error bars larger than the ones appearing in the calibration of the extragalactic distance ladder. However, the remarkable complementarity among the four tests works efficiently in reducing greatly the possible degeneracy on the space parameter (Omega_m,h) ultimately providing a value of H_0 that is in excellent agreement with the determination using recessional velocities and distances to nearby objects.Comment: 13 pages, 6 figures, shorter title, several style modifications, typos corrected, accepted for publication in the Astrophysical J. Letter

    Skein Theory and Topological Quantum Registers: Braiding Matrices and Topological Entanglement Entropy of Non-Abelian Quantum Hall States

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    We study topological properties of quasi-particle states in the non-Abelian quantum Hall states. We apply a skein-theoretic method to the Read--Rezayi state whose effective theory is the SU(2)_K Chern--Simons theory. As a generalization of the Pfaffian (K=2) and the Fibonacci (K=3) anyon states, we compute the braiding matrices of quasi-particle states with arbitrary spins. Furthermore we propose a method to compute the entanglement entropy skein-theoretically. We find that the entanglement entropy has a nontrivial contribution called the topological entanglement entropy which depends on the quantum dimension of non-Abelian quasi-particle intertwining two subsystems.Comment: 42 pages, many eps file

    SU(m) non-Abelian anyons in the Jain hierarchy of quantum Hall states

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    We show that different classes of topological order can be distinguished by the dynamical symmetry algebra of edge excitations. Fundamental topological order is realized when this algebra is the largest possible, the algebra of quantum area-preserving diffeomorphisms, called W1+∞W_{1+\infty}. We argue that this order is realized in the Jain hierarchy of fractional quantum Hall states and show that it is more robust than the standard Abelian Chern-Simons order since it has a lower entanglement entropy due to the non-Abelian character of the quasi-particle anyon excitations. These behave as SU(mm) quarks, where mm is the number of components in the hierarchy. We propose the topological entanglement entropy as the experimental measure to detect the existence of these quantum Hall quarks. Non-Abelian anyons in the ν=2/5\nu = 2/5 fractional quantum Hall states could be the primary candidates to realize qbits for topological quantum computation.Comment: 5 pages, no figures, a few typos corrected, a reference adde
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