2,919 research outputs found

    Hole mobility in organic single crystals measured by a "flip-crystal" field-effect technique

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    We report on single crystal high mobility organic field-effect transistors (OFETs) prepared on prefabricated substrates using a "flip-crystal" approach. This method minimizes crystal handling and avoids direct processing of the crystal that may degrade the FET electrical characteristics. A chemical treatment process for the substrate ensures a reproducible device quality. With limited purification of the starting materials, hole mobilities of 10.7, 1.3, and 1.4 cm^2/Vs have been measured on rubrene, tetracene, and pentacene single crystals, respectively. Four-terminal measurements allow for the extraction of the "intrinsic" transistor channel resistance and the parasitic series contact resistances. The technique employed in this study shows potential as a general method for studying charge transport in field-accumulated carrier channels near the surface of organic single crystals.Comment: 26 pages, 7 figure

    Urban-rural comparison of adult day care centres in British Columbia

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    In 1979, Adult Day Care became a part of the B.C. Ministry of Health\u27s Continuing Care Program. By 1989, there were 49 centres in operation in the province and it was felt timely to undertake a comprehensive review of the Adult Day Care component of the Continuing Care Program. As part of that review and as an aid for future planning, the Simon Fraser University Gerontology Research Centre was commissioned to conduct a study that would provide information concerning: 1. activities and services provided by the 49 centres; 2. characteristics of the clients currently being served; 3. reasons clients are referred to Adult Day Care; 4. reasons some referred clients do not attend; and 5. the referral process and the interface between the Long Term Care Program and Adult Day Care

    Adult day care centres in British Columbia : their operating characteristics, activities and services, clients, and interface with the long term care program. Final report.

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    Previews the literature concerning the objectives, models of service delivery, operating characteristics, activities, services and clients of Adult Day Care (ADC) Centres. Presents findings from a 3-phase study conducted in British Columbia. In phase 1, a 100% sample of B.C. ADCs provided information on their operating characteristics, activities and services. In phase 2, the characteristics of 479 new admissions to 22 ADCs were determined. Phase 3 focused on reasons for referring clients to ADC, why some referred clients do not attend and on the interface between ADCs and the province\u27s Continuing Care Program

    Ballistic transport in disordered graphene

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    An analytic theory of electron transport in disordered graphene in a ballistic geometry is developed. We consider a sample of a large width W and analyze the evolution of the conductance, the shot noise, and the full statistics of the charge transfer with increasing length L, both at the Dirac point and at a finite gate voltage. The transfer matrix approach combined with the disorder perturbation theory and the renormalization group is used. We also discuss the crossover to the diffusive regime and construct a ``phase diagram'' of various transport regimes in graphene.Comment: 23 pages, 10 figure

    Zero bias anomaly out of equilibrium

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    The non-equilibrium zero bias anomaly (ZBA) in the tunneling density of states of a diffusive metallic film is studied. An effective action describing virtual fluctuations out-of-equilibrium is derived. The singular behavior of the equilibrium ZBA is smoothed out by real processes of inelastic scattering.Comment: 4 page

    Full counting statistics of a chaotic cavity with asymmetric leads

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    We study the statistics of charge transport in a chaotic cavity attached to external reservoirs by two openings of different size which transmit non-equal number of quantum channels. An exact formula for the cumulant generating function has been derived by means of the Keldysh-Green function technique within the circuit theory of mesoscopic transport. The derived formula determines the full counting statistics of charge transport, i.e., the probability distribution and all-order cumulants of current noise. It is found that, for asymmetric cavities, in contrast to other mesoscopic systems, the third-order cumulant changes the sign at high biases. This effect is attributed to the skewness of the distribution of transmission eigenvalues with respect to forward/backward scattering. For a symmetric cavity we find that the third cumulant approaches a voltage-independent constant proportional to the temperature and the number of quantum channels in the leads.Comment: new section on probability distribution and new references adde

    Leibnizian, Robinsonian, and Boolean Valued Monads

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    This is an overview of the present-day versions of monadology with some applications to vector lattices and linear inequalities.Comment: This is a talk prepared for the 20th St. Petersburg Summer Meeting in Mathematical Analysis, June 24-29, 201

    Non-equilibrium Luttinger liquid: Zero-bias anomaly and dephasing

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    A one-dimensional system of interacting electrons out of equilibrium is studied in the framework of the Luttinger liquid model. We analyze several setups and develop a theory of tunneling into such systems. A remarkable property of the problem is the absence of relaxation in energy distribution functions of left- and right-movers, yet the presence of the finite dephasing rate due to electron-electron scattering, which smears zero-bias-anomaly singularities in the tunneling density of states.Comment: 5 pages, 2 figure

    On the Stability of Thermonuclear Burning Fronts in Type Ia Supernovae

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    The propagation of cellularly stabilized thermonuclear flames is investigated by means of numerical simulations. In Type Ia supernova explosions the corresponding burning regime establishes at scales below the Gibson length. The cellular flame stabilization - which is a result of an interplay between the Landau-Darrieus instability and a nonlinear stabilization mechanism - is studied for the case of propagation into quiescent fuel as well as interaction with vortical fuel flows. Our simulations indicate that in thermonuclear supernova explosions stable cellular flames develop around the Gibson scale and that deflagration-to-detonation transition is unlikely to be triggered from flame evolution effects here.Comment: 6 pages, 2 figures, to appear in the proceedings of the IAU Colloquium 192, "Supernovae (10 years of SN1993J)", 22-26 April 2003, Valencia, Spain, Eds. J.M. Marcaide and K.W. Weiler, Springer Verla

    Many-particle correlations in non-equilibrium Luttinger liquid

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    We develop an operator-based approach to the problem of Luttinger liquid conductor in a non-equilibrium stationary state. We show that the coherent-state many-body fermionic density matrix as well as all fermionic correlation functions out of equilibrium are given by one-dimensional functional determinants of the Fredholm type. Thus, the model constitutes a remarkable example of a many-body problem where all the correlation functions can be evaluated exactly. On the basis of the general formalism we investigate four-point correlation functions of the fermions coming out of the Luttinger liquid wire. Obtained correlations in the fermionic distribution functions represent the combined effect of interaction and non-equilibrium conditions.Comment: 23 pages,7 figure
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