2,382 research outputs found

    On intersection of domain walls in a supersymmetric model

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    We consider a classical field configuration, corresponding to intersection of two domain walls in a supersymmetric model, where the field profile for two parallel walls at a finite separation is known explicitly. An approximation to the solution for intersecting walls is constructed for a small angle at the intersection. We find a finite effective length of the intersection region and also an energy, associated with the intersection.Comment: 12 pages, LaTeX, 4 figures, ep

    Formation of three-particle clusters in hetero-junctions and MOSFET structures

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    A novel interaction mechanism in MOSFET structures and GaAs/AlGaAsGaAs/AlGaAs hetero-junctions between the zone electrons of the two-dimensional (2D) gas and the charged traps on the insulator side is considered. By applying a canonical transformation, off-diagonal terms in the Hamiltonian due to the trapped level subsystem are excluded. This yields an effective three-particle attractive interaction as well as a pairing interaction inside the 2D electronic band. A type of Bethe- Goldstone equation for three particles is studied to clarify the character of the binding and the energy of the three-particle bound states. The results are used to offer a possible explanation of the Metal-Insulator transition recently observed in MOSFET and hetero-junctions.Comment: 4 page

    Chemical changes in skin mucin as an index of early stages of spoilage in fish

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    Results of a preliminary investigation on the overall chemical nature of fish skin mucin in lung fish, Clarias batrachus, with special reference to water soluble low molecular weight compounds, are presented. Changes observed during room temperature spoilage have been studied with a view to present a new approach towards the assessment of freshness in fish inspection. pH of the mucin was distinctly alkaline (8.2) and remained unchanged during spoilage. Much of the nitrogen was found to be present in the glycoprotein fraction. Free amino acids and purine bases were present in appreciable quantities in the aqueous extracts which registered a significant increase after 10 hrs. Post-mortem increase in total solids was accompanied by a slight rise in protein nitrogen which may indicate tissue breakdown. Increase in TVN was also observed to occur earlier in the outside mucin as compared to the inside muscle. Presence of free sugars or sialic acid could not be confirmed nor was there any indication of cholesterol and lipoid material as stated in earlier literature

    Mind your meat: Religious differences in the social perception of animals

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    While previous work demonstrated that animals are categorised based on their edibility, little research has systematically evaluated the role of religion in the perception of animal edibility, particularly when specific animals are deemed sacred in a religion. In two studies, we explored a key psychological mechanism through which sacred animals are deemed inedible by members of a faith: mind attribution. In Study 1, non-vegetarian Hindus in Singapore (N = 70) evaluated 19 animals that differed in terms of their sacredness and edibility. Results showed that participants categorised animals into three groups: holy animals (high sacredness but low edibility), food animals (low sacredness but high edibility) and neutral animals (low sacredness and low edibility). Holy animals were deemed to possess greater mental life compared to other animal categories. In Study 2, we replicated this key finding with Hindus in India (N = 100), and further demonstrated that the observed pattern of results was specific to Hindus but not Muslims (N = 90). In both studies, mind attribution mediated the negative association between sacredness and edibility. Our findings illustrate how religious groups diverge in animal perception, thereby highlighting the role of mind attribution as a crucial link between sacredness and edibility

    Ground state properties of the 2D disordered Hubbard model

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    We study the ground state of the two-dimensional (2D) disordered Hubbard model by means of the projector quantum Monte Carlo (PQMC) method. This approach allows us to investigate the ground state properties of this model for lattice sizes up to 10×1010 \times 10, at quarter filling, for a broad range of interaction and disorder strengths. Our results show that the ground state of this system of spin-1/2 fermions remains localised in the presence of the short-ranged Hubbard interaction.Comment: 7 pages, 9 figure

    In-medium kaon and antikaon properties in the quark-meson coupling model

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    The properties of the kaon, KK, and antikaon, \kbar, in nuclear medium are studied in the quark-meson coupling (QMC) model. Employing a constituent quark-antiquark (MIT bag model) picture, their excitation energies in a nuclear medium at zero momentum are calculated within mean field approximation. The scalar, and the vector mesons are assumed to couple directly to the nonstrange quarks and antiquarks in the KK and \kbar mesons. It is demonstrated that the ρ\rho meson induces different mean field potentials for each member of the isodoublets, KK and \kbar, when they are embedded in asymmetric nuclear matter. Furthermore, it is also shown that this ρ\rho meson potential is repulsive for the KK^- meson in matter with a neutron excess, and renders KK^- condensation less likely to occur.Comment: Latex, 11 pages, 4 Postscript figures, a few typos which can be important for an interpretation (but not reflected in the results) are corrected, as published in (E) Phys. Lett. B 436 (1998) 45

    The electronic transport properties and microstructure of carbon nanofiber/epoxy composites

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    Carbon nanofibres (CNF) were dispersed into an epoxy resin using a combination of ultrasonication and mechanical mixing. The electronic transport properties of the resulting composites were investigated by means of impedance spectroscopy. It was found that a very low critical weight fraction (pc = 0.064 wt %) which may be taken to correspond to the formation of a tunneling conductive network inside the matrix. The insulator-to-conductor transition region spanned about one order of magnitude from 0.1 to 1 wt %. Far from the transition, the conductivity increased by two orders of magnitude. This increase and the low value of the conductivity were explained in terms of the presence of an epoxy film at the contact between CNF. A simple model based on the CNF-CNF contact network inside the matrix was proposed in order to evaluate the thickness of that film.Comment: 7 page

    A complete solution of a Constrained System: SUSY Monopole Quantum Mechanics

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    We solve the quantum mechanical problem of a charged particle on S^2 in the background of a magnetic monopole for both bosonic and supersymmetric cases by constructing Hilbert space and realizing the fundamental operators obeying complicated Dirac bracket relations in terms of differential operators. We find the complete energy eigenfunctions. Using the lowest energy eigenstates we count the number of degeneracies and examine the supersymmetric structure of the ground states in detail.Comment: 20 pages including the title, prepared in JHEP forma

    An ARPES view on the high-Tc problem: phonons vs spin-fluctuations

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    We review the search for a mediator of high-Tc superconductivity focusing on ARPES experiment. In case of HTSC cuprates, we summarize and discuss a consistent view of electronic interactions that provides natural explanation of both the origin of the pseudogap state and the mechanism for high temperature superconductivity. Within this scenario, the spin-fluctuations play a decisive role in formation of the fermionic excitation spectrum in the normal state and are sufficient to explain the high transition temperatures to the superconducting state while the pseudogap phenomenon is a consequence of a Peierls-type intrinsic instability of electronic system to formation of an incommensurate density wave. On the other hand, a similar analysis being applied to the iron pnictides reveals especially strong electron-phonon coupling that suggests important role of phonons for high-Tc superconductivity in pnictides.Comment: A summary of the ARPES part of the Research Unit FOR538, http://for538.wmi.badw.d
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