Nonlinear conductance of long quantum wires at a conductance plateau transition: Where does the voltage drop?

We calculate the linear and nonlinear conductance of spinless fermions in clean, long quantum wires where short-ranged interactions lead locally to equilibration. Close to the quantum phase transition where the conductance jumps from zero to one conductance quantum, the conductance obtains an universal form governed by the ratios of temperature, bias voltage and gate voltage. Asymptotic analytic results are compared to solutions of a Boltzmann equation which includes the effects of three-particle scattering. Surprisingly, we find that for long wires the voltage predominantly drops close to one end of the quantum wire due to a thermoelectric effect.Comment: 4+ pages, 3 figures plus supplementary material (2 pages, 1 figure); minor changes, references correcte

New classes of exact solutions of three-dimensional Navier-Stokes equations

New classes of exact solutions of the three-dimensional unsteady Navier-Stokes equations containing arbitrary functions and parameters are described. Various periodic and other solutions, which are expressed through elementary functions are obtained. The general physical interpretation and classification of solutions is given.Comment: 11 page

Optical conductivity of one-dimensional doped Hubbard-Mott insulator

We study the optical response of a strongly correlated electron system near the metal-insulator transition using a mapping to the sine-Gordon model. With semiclassical quantization, the spectral weight is distributed between a Drude peak and absorption lines due to breathers. We calculate the Drude weight, the optical gap, and the lineshape of breather absorption.Comment: 4 pages, 2 EPS figures, REVTEX 4, a final versio

Transport properties of copper phthalocyanine based organic electronic devices

Ambipolar charge carrier transport in Copper phthalocyanine (CuPc) is studied experimentally in field-effect transistors and metal-insulator-semiconductor diodes at various temperatures. The electronic structure and the transport properties of CuPc attached to leads are calculated using density functional theory and scattering theory at the non-equilibrium Green's function level. We discuss, in particular, the electronic structure of CuPc molecules attached to gold chains in different geometries to mimic the different experimental setups. The combined experimental and theoretical analysis explains the dependence of the mobilityand the transmission coefficient on the charge carrier type (electrons or holes) and on the contact geometry. We demonstrate the correspondence between our experimental results on thick films and our theoretical studies of single molecule contacts. Preliminary results for fluorinated CuPc are discussed.Comment: 18 pages, 16 figures; to be published in Eur. Phys. J. Special Topic

Kinetic Theory of a Dilute Gas System under Steady Heat Conduction

The velocity distribution function of the steady-state Boltzmann equation for hard-core molecules in the presence of a temperature gradient has been obtained explicitly to second order in density and the temperature gradient. Some thermodynamical quantities are calculated from the velocity distribution function for hard-core molecules and compared with those for Maxwell molecules and the steady-state Bhatnagar-Gross-Krook(BGK) equation. We have found qualitative differences between hard-core molecules and Maxwell molecules in the thermodynamical quantities, and also confirmed that the steady-state BGK equation belongs to the same universality class as Maxwell molecules.Comment: 36 pages, 4 figures, 5 table

Density of states for dirty d-wave superconductors: A unified and dual approach for different types of disorder

A two-parameter field theoretical representation is given of a 2-dimensional dirty d-wave superconductor that interpolates between the Gaussian limit of uncorrelated weak disorder and the unitary limit of a dilute concentration of resonant scatterers. It is argued that a duality holds between these two regimes from which follows that a linearly vanishing density of states in the Gaussian limit transforms into a diverging one in the unitary limit arbitrarily close to the Fermi energy

Systematic study of niobium thermal treatments for superconducting radio frequency cavities employing x ray photoelectron spectroscopy

The structural and chemical composition of the surface layer 100 140 nm of niobium radiofrequency cavities operating at cryogenic temperature has enormous impact on their superconducting characteristics. During the last years, cavities treated with a new thermal processing recipe, so called nitrogen infusion, have demonstrated an increased efficiency and high accelerating gradients. The role and importance of nitrogen gas has been a topic of many debates. In the present work we employ variable energy synchrotron x ray photoelectron spectroscopy XPS , to study the niobium surface subjected to the following treatments vacuum annealing at 800 C, nitrogen infusion, and vacuum heat treatment as for the infusion process but without nitrogen supply. Careful analysis of XPS energy distribution curves revealed a slightly increased thickness of the native oxide Nb2O5 for the infused samples amp; 8764;3.8 nm as compared to the annealed one amp; 8764;3.5 nm which indicates insignificant oxygen incorporation into niobium during 120 C baking and no effect of nitrogen on the formation of oxides or other niobium phases. By conducting an additional in situ annealing experiment and analyzing the niobium after the failed infusion process, we conclude that the vacuum furnace hygiene particularly during the high temperature stage is the prerequisite for success of any treatment recip

Electronic properties and Fermi surface of Ag(111) films deposited onto H-passivated Si(111)-(1x1) surfaces

Silver films were deposited at room temperature onto H-passivated Si(111) surfaces. Their electronic properties have been analyzed by angle-resolved photoelectron spectroscopy. Submonolayer films were semiconducting and the onset of metallization was found at a Ag coverage of $\sim$0.6 monolayers. Two surface states were observed at $\bar{\Gamma}$-point in the metallic films, with binding energies of 0.1 and 0.35 eV. By measurements of photoelectron angular distribution at the Fermi level in these films, a cross-sectional cut of the Fermi surface was obtained. The Fermi vector determined along different symmetry directions and the photoelectron lifetime of states at the Fermi level are quite close to those expected for Ag single crystal. In spite of this concordance, the Fermi surface reflects a sixfold symmetry rather than the threefold symmetry of Ag single crystal. This behavior was attributed to the fact that these Ag films are composed by two domains rotated 60$^o$.Comment: 9 pages, 8 figures, submitted to Physical Review

X-ray photoemission spectroscopic investigation of surface treatments, metal deposition, and electron accumulation on InN

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Implementation of the Project on the Prevention of Primary Smoking Among Children and Adolescents “I Breathe Freely!”

Annually, tobacco causes almost 6 million deaths, of which more than 5 million cases occur among consumers and former tobacco users, and more than 600,000 are among non-smokers exposed to second-hand smoke. According to the Research Institute of Hygiene and Health Protection of Children and Adolescents, 36,6 % of boys are trying to smoke at 11 years old and earlier (9 years — 18,1 %, 13–14 years — 22,2 %). Among girls, the highest percentage of testers was observed at 13 and 14 years (18,3 % and 16,7 %, respectively). The reasons for the first test are misunderstanding of others, the desire to become an adult, imitation of a bad example, problems in the family, school.Ежегодно табак приводит почти к шести миллионам случаев смерти, из которых более пяти миллионов случаев происходит среди потребителей и бывших потребителей табака и более шестисот тысяч — среди некурящих людей, подвергающихся воздействию вторичного табачного дыма. По данным НИИ гигиены и охраны здоровья детей и подростков ГУ НЦЗД РАМН, 36,6 % мальчиков пробуют курить в 11 лет и раньше (9 лет — 18,1 %, 13–14 лет — 22,2; %). Среди девочек наибольший процент пробующих курение отмечается в 13 и 14 лет (18,3 % и 16,7 % соответственно). Причинами первой пробы становится непонимание окружающих, стремление стать взрослым, подражание плохому примеру, проблемы в семье, школе