9 research outputs found

    Observation of diffractive orbits in the spectrum of excited NO in a magnetic field

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    We investigate the experimental spectra of excited NO molecules in the diamagnetic regime and develop a quantitative semiclassical framework to account for the results. We show the dynamics can be interpreted in terms of classical orbits provided that in addition to the geometric orbits, diffractive effects are appropriately taken into account. We also show how individual orbits can be extracted from the experimental signal and use this procedure to reveal the first experimental manifestation of inelastic diffractive orbits.Comment: 4 fig

    Mesoscopic scattering in the half-plane: squeezing conductance through a small hole

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    We model the 2-probe conductance of a quantum point contact (QPC), in linear response. If the QPC is highly non-adiabatic or near to scatterers in the open reservoir regions, then the usual distinction between leads and reservoirs breaks down and a technique based on scattering theory in the full two-dimensional half-plane is more appropriate. Therefore we relate conductance to the transmission cross section for incident plane waves. This is equivalent to the usual Landauer formula using a radial partial-wave basis. We derive the result that an arbitrarily small (tunneling) QPC can reach a p-wave channel conductance of 2e^2/h when coupled to a suitable reflector. If two or more resonances coincide the total conductance can even exceed this. This relates to recent mesoscopic experiments in open geometries. We also discuss reciprocity of conductance, and the possibility of its breakdown in a proposed QPC for atom waves.Comment: 8 pages, 3 figures, REVTeX. Revised version (shortened), accepted for publication in PR

    The Determinants of Trade Credit in Transition Countries

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    The paper investigates the determinants of trade credit in transition countries. Traditional theories of trade credit extension suggest that both financial and commercial motives may induce non-financial companies to assume a role of financial intermediation. Furthermore, specific conditions of financing for companies in transition countries may reserve to trade credit an important role in financial structure. We test the determinants of accounts receivable and accounts payable on a sample of about 9300 companies from nine Central and Eastern European Countries. Results suggest that both financial and commercial motives explain the credit behaviour of firms. However, we do not find generalised patterns in the use of trade credit among all transition countries. Copyright Springer 2005trade credit, transition economies, G32, P34,

    The Neuroprotective Role of Creatine

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    Mitochondrial and metabolic-based protective strategies in Huntington’s disease: the case of creatine and coenzyme Q

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