6,248 research outputs found

    Forbidden island heights in stress-driven coherent Stranski-Krastanov growth

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    The observed height distribution of clusters obtained in strained epitaxy has been often interpreted in terms of electronic effects. We show that some aspects can be explained classically by the interplay of strain and edge energies. We find that soft materials can transform directly from monolayer into thicker islands by two-dimensional (2D) multilayer nucleation and growth. There is a critical thickness decreasing with the force constant. Thinner islands are thermodynamically forbidden, due to the insufficient stress relaxation upon clustering particularly under tensile stress. At sufficiently large misfits the barrier for 2D multilayer nucleation is significantly smaller than the barrier for subsequent single-layer nucleation. The effects are found to be quantitatively reasonable and offer a plausible explanation for the absence of thin islands and 2D growth of flattop islands usually attributed to quantum size effects.Comment: 4 pages, 4 figures. Accepted version. Includes quantitative estimations comparing with experiments plus minor change

    Higgs bundles over elliptic curves

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    In this paper we study GG-Higgs bundles over an elliptic curve when the structure group GG is a classical complex reductive Lie group. Modifying the notion of family, we define a new moduli problem for the classification of semistable GG-Higgs bundles of a given topological type over an elliptic curve and we give an explicit description of the associated moduli space as a finite quotient of a product of copies of the cotangent bundle of the elliptic curve. We construct a bijective morphism from this new moduli space to the usual moduli space of semistable GG-Higgs bundles, proving that the former is the normalization of the latter. We also obtain an explicit description of the Hitchin fibration for our (new) moduli space of GG-Higgs bundles and we study the generic and non-generic fibres

    Hamevol1.0: a C++ code for differential equations based on Runge-Kutta algorithm. An application to matter enhanced neutrino oscillation

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    We present a C++ implementation of a fifth order semi-implicit Runge-Kutta algorithm for solving Ordinary Differential Equations. This algorithm can be used for studying many different problems and in particular it can be applied for computing the evolution of any system whose Hamiltonian is known. We consider in particular the problem of calculating the neutrino oscillation probabilities in presence of matter interactions. The time performance and the accuracy of this implementation is competitive with respect to the other analytical and numerical techniques used in literature. The algorithm design and the salient features of the code are presented and discussed and some explicit examples of code application are given.Comment: 18 pages, Late

    Generating and verifying graph states for fault-tolerant topological measurement-based quantum computing in 2D optical lattices

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    We propose two schemes for implementing graph states useful for fault-tolerant topological measurement-based quantum computation in 2D optical lattices. We show that bilayer cluster and surface code states can be created by global single-row and controlled-Z operations. The schemes benefit from the accessibility of atom addressing on 2D optical lattices and the existence of an efficient verification protocol which allows us to ensure the experimental feasibility of measuring the fidelity of the system against the ideal graph state. The simulation results show potential for a physical realization toward fault-tolerant measurement-based quantum computation against dephasing and unitary phase errors in optical lattices.Comment: 6 pages and 4 figures (minor changed

    Flack

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    Fiction by Emilio P. Ratti

    Characterization of a novel human CAP2 interacting protein: Neuronal calcium binding protein 1 (Necab1).

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    The actin cytoskeleton is implicated in numerous processes such as cellular division, migration, endocytosislexocytosis, and more recently synaptic plasticity. Important players in controlling cytoskeletal rearrangements are the Cyclase Associated Proteins (CAPs) which are thought to link cell signalling to the dynamics of the actin cytoskeleton, via sequestration of monomeric actin subunits. CAPs are conserved throughout evolution and possess conserved functional domains. Previous studies have suggested a link between CAP proteins and vesicle trafficking and this study focussed on characterizing binding partners of human CAPs. Using a two hybrid screen of a human adult brain cDNA library, a novel human CAP interacting protein named Neuronal calcium binding protein 1 (Necab1) has been isolated. Necab1 is a 351 amino acid protein containing a predicted calcium binding EF-hand and three coiled-coil domains. It is highly expressed in human brain, and similar to CAP2, displays high levels of expression within the hippocampus and cerebral cortex of rat brain. In vitro binding and in vivo immunoprecipitations demonstrate that CAP2 interacts with Necab1. (Abstract shortened by UMI.)Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2002 .M68. Source: Masters Abstracts International, Volume: 43-01, page: 0215. Adviser: A. V. Hubberstey. Thesis (M.Sc.)--University of Windsor (Canada), 2003
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