6,907 research outputs found

    The body in the library: adventures in realism

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    This essay looks at two aspects of the virtual ‘material world’ of realist fiction: objects encountered by the protagonist and the latter’s body. Taking from Sartre two angles on the realist pact by which readers agree to lend their bodies, feelings, and experiences to the otherwise ‘languishing signs’ of the text, it goes on to examine two sets of first-person fictions published between 1902 and 1956 — first, four modernist texts in which banal objects defy and then gratify the protagonist, who ends up ready and almost able to write; and, second, three novels in which the body of the protagonist is indeterminate in its sex, gender, or sexuality. In each of these cases, how do we as readers make texts work for us as ‘an adventure of the body’

    Quantum heat transfer: A Born Oppenheimer method

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    We develop a Born-Oppenheimer type formalism for the description of quantum thermal transport along hybrid nanoscale objects. Our formalism is suitable for treating heat transfer in the off-resonant regime, where e.g., the relevant vibrational modes of the interlocated molecule are high relative to typical bath frequencies, and at low temperatures when tunneling effects dominate. A general expression for the thermal energy current is accomplished, in the form of a generalized Landauer formula. In the harmonic limit this expression reduces to the standard Landauer result for heat transfer, while in the presence of nonlinearities multiphonon tunneling effects are realized

    Birkhoff strata of the Grassmannian Gr(2)\mathrm{^{(2)}}: Algebraic curves

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    Algebraic varieties and curves arising in Birkhoff strata of the Sato Grassmannian Gr(2){^{(2)}} are studied. It is shown that the big cell Σ0\Sigma_0 contains the tower of families of the normal rational curves of all odd orders. Strata Σ2n\Sigma_{2n}, n=1,2,3,...n=1,2,3,... contain hyperelliptic curves of genus nn and their coordinate rings. Strata Σ2n+1\Sigma_{2n+1}, n=0,1,2,3,...n=0,1,2,3,... contain (2m+1,2m+3)−(2m+1,2m+3)-plane curves for n=2m,2m−1n=2m,2m-1 (m≥2)(m \geq 2) and (3,4)(3,4) and (3,5)(3,5) curves in Σ3\Sigma_3, Σ5\Sigma_5 respectively. Curves in the strata Σ2n+1\Sigma_{2n+1} have zero genus.Comment: 14 pages, no figures, improved some definitions, typos correcte

    Transition amplitudes and sewing properties for bosons on the Riemann sphere

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    We consider scalar quantum fields on the sphere, both massive and massless. In the massive case we show that the correlation functions define amplitudes which are trace class operators between tensor products of a fixed Hilbert space. We also establish certain sewing properties between these operators. In the massless case we consider exponential fields and have a conformal field theory. In this case the amplitudes are only bilinear forms but still we establish sewing properties. Our results are obtained in a functional integral framework.Comment: 33 page

    Towards a definition of quantum integrability

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    We briefly review the most relevant aspects of complete integrability for classical systems and identify those aspects which should be present in a definition of quantum integrability. We show that a naive extension of classical concepts to the quantum framework would not work because all infinite dimensional Hilbert spaces are unitarily isomorphic and, as a consequence, it would not be easy to define degrees of freedom. We argue that a geometrical formulation of quantum mechanics might provide a way out.Comment: 37 pages, AmsLatex, 1 figur

    Heat flux operator, current conservation and the formal Fourier's law

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    By revisiting previous definitions of the heat current operator, we show that one can define a heat current operator that satisfies the continuity equation for a general Hamiltonian in one dimension. This expression is useful for studying electronic, phononic and photonic energy flow in linear systems and in hybrid structures. The definition allows us to deduce the necessary conditions that result in current conservation for general-statistics systems. The discrete form of the Fourier's Law of heat conduction naturally emerges in the present definition

    Quantum mechanics on manifolds and topological effects

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    A unique classification of the topological effects associated to quantum mechanics on manifolds is obtained on the basis of the invariance under diffeomorphisms and the realization of the Lie-Rinehart relations between the generators of the diffeomorphism group and the algebra of infinitely differentiable functions on the manifold. This leads to a unique ("Lie-Rinehart") C* algebra as observable algebra; its regular representations are shown to be locally Schroedinger and in one to one correspondence with the unitary representations of the fundamental group of the manifold. Therefore, in the absence of spin degrees of freedom and external fields, the first homotopy group of the manifold appears as the only source of topological effects.Comment: A few comments have been added to the Introduction, together with related references; a few words have been changed in the Abstract and a Note added to the Titl

    Spectral Geometry of Heterotic Compactifications

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    The structure of heterotic string target space compactifications is studied using the formalism of the noncommutative geometry associated with lattice vertex operator algebras. The spectral triples of the noncommutative spacetimes are constructed and used to show that the intrinsic gauge field degrees of freedom disappear in the low-energy sectors of these spacetimes. The quantum geometry is thereby determined in much the same way as for ordinary superstring target spaces. In this setting, non-abelian gauge theories on the classical spacetimes arise from the K-theory of the effective target spaces.Comment: 14 pages LaTe

    Existence of long-lived isotopes of a superheavy element in natural Au

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    Evidence for the existence of long-lived isotopes with atomic mass numbers 261 and 265 and abundance of (1-10)x10−10^{-10} relative to Au has been found in a study of natural Au using an inductively coupled plasma - sector field mass spectrometer. The measured masses fit the predictions made for the masses of 261^{261}Rg and 265^{265}Rg (Z=111) and for some isotopes of nearby elements. The possibility that these isotopes belong to the recently discovered class of long-lived high spin super- and hyperdeformed isomeric states is discussed.Comment: 4 pages, 3 figures, 2 table

    Laser cooling in the Penning trap: an analytical model for cooling rates in the presence of an axializing field

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    Ions stored in Penning traps may have useful applications in the field of quantum information processing. There are, however, difficulties associated with the laser cooling of one of the radial motions of ions in these traps, namely the magnetron motion. The application of a small radio-frequency quadrupolar electric potential resonant with the sum of the two radial motional frequencies has been shown to couple these motions and to lead to more efficient laser cooling. We present an analytical model that enables us to determine laser cooling rates in the presence of such an 'axializing' field. It is found that this field leads to an averaging of the laser cooling rates for the two motions and hence improves the overall laser cooling efficiency. The model also predicts shifts in the motional frequencies due to the axializing field that are in qualitative agreement with those measured in recent experiments. It is possible to determine laser cooling rates experimentally by studying the phase response of the cooled ions to a near resonant excitation field. Using the model developed in this paper, we study the expected phase response when an axializing field is present.Comment: 22 pages, 7 figure
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