1,668 research outputs found

    Electronic transport in Si:P delta-doped wires

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    Despite the importance of Si:P delta-doped wires for modern nanoelectronics, there are currently no computational models of electron transport in these devices. In this paper we present a nonequilibrium Green's function model for electronic transport in a delta-doped wire, which is described by a tight-binding Hamiltonian matrix within a single-band effective-mass approximation. We use this transport model to calculate the current-voltage characteristics of a number of delta-doped wires, achieving good agreement with experiment. To motivate our transport model we have performed density-functional calculations for a variety of delta-doped wires, each with different donor configurations. These calculations also allow us to accurately define the electronic extent of a delta-doped wire, which we find to be at least 4.6 nm.Comment: 13 pages, 11 figure

    Are roadwork zones safe?

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    Increasing heavy traffic volumes and ageing of road infrastructure cause road pavement degradation, which leads to the need for repaving or rehabilitation activities – roadwork. As cars are much more enhanced than previous decade, drivers accept roadwork zone as a common condition. Work zones present more complex driving environment in consequence of possible accidents. Accidents in roadwork zones are significant problem in all European countries while noncompliance with speed limits is one of the major safety concerns. The article gives an overview of the existing traffic safety situation in roadwork zones through the EU countries. Analysis of traffic speed of different layout work zones and accidents statistics on the Lithuanian national road network is presented. Based on research this research. The most effective traffic calming measures are highlighted

    A study of collider signatures for two Higgs doublet models with a Pseudoscalar mediator to Dark Matter

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    Two Higgs doublet models with an additional pseudoscalar particle coupling to the Standard Model and to a new stable, neutral particle, provide an attractive and fairly minimal route to solving the problem of Dark Matter. They have been the subject of several searches at the LHC. We study the impact of existing LHC measurements on such models, first in the benchmark regions addressed by searches and then after relaxing some of their assumptions and broadening the parameter ranges considered. In each case we study how the new parameters change the potentially visible signatures at the LHC, and identify which of these signatures should already have had a significant impact on existing measurements. This allows us to set some first constraints on a number of so far unstudied scenarios.Comment: 20 pages, 9 figures; added EW constraints contours, extended explanation of WW model-dependency, extended motivation for pseudoscalar mediators, corrected typo

    Metabolic effects of FGF-21: thermoregulation and beyond

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    Fibroblast growth factor (FGF)-21, a member of the FGF family, is a novel hormone involved in the control of metabolism by modulating glucose homeostasis, insulin sensitivity, ketogenesis, and promoting adipose tissue “browning.” Recent studies demonstrated that brown adipose tissue is not only a target for FGF-21, but is also a potentially important source of systemic FGF-21. These findings support the hypothesis that FGF-21 plays a physiologic role in thermogenesis and thermogenic recruitment of white adipose tissue by an autocrine–paracrine axis. This review examines the role of FGF-21 in thermogenesis from the perspective of cell-based, animal model, and human studies. We also present recent advances in the characterization of FGF-21’s regulation of metabolism

    A quantum algorithm for solving open system dynamics on quantum computers using noise

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    In this paper we present a quantum algorithm that uses noise as a resource. The goal of our quantum algorithm is the calculation of operator averages of an open quantum system evolving in time. Selected low-noise system qubits and noisy bath qubits represent the system and the bath of the open quantum system. All incoherent qubit noise can be mapped to bath spectral functions. The form of the spectral functions can be tuned digitally, allowing for the time evolution of a wide range of open-system models at finite temperature. We study the feasibility of this approach with a focus on the solution of the spin-boson model and assume intrinsic qubit noise that is dominated by damping and dephasing. We find that classes of open quantum systems exist where our algorithm performs very well, even with gate errors as high as 1%. In general the presented algorithm performs best if the system-bath interactions can be decomposed into native gates.Comment: 19 pages, 8 figures in total: 10 pages main text with 7 figure

    Density, adhesion and stiffness of warm mix asphalts

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    XI Congreso de Ingeniería del Transporte (CIT 2014)This study presents the results of different laboratory tests related to the density, adhesion (sensitivity to water test) and rigidity (resilient module) of bituminous mixtures, manufactured at three different temperatures (160 °C, 140 °C and 120 °C), with three additives: a surfactant made up of different amino substances, a paraffin obtained by the Fisher-Tropsch synthesis process which is totally soluble in bitumen, and a synthetic zeolite in powder form which causes the bitumen to micro-foam,. Test samples have been compacted by impact, according to the Marshall method, and kneading, according to gyratory machine. To evaluate these properties an asphalt concrete mixture has been chosen, with a binder, B-50/70, and a maximum size of aggregates of 16 mm, which is usually placed in the surface layer of the pavement. The densities obtained by the two compaction methods are easy to reach. Densities will decrease if the temperature of manufacturing is lower. All mixtures compacted by gyratory machine at different temperatures displayed very good behavior of water sensitivity; but not all mixtures compacted by impact achieved this. The additives improve the adhesion between aggregate and binder. The stiffness moduli decreased in all mixtures for both types of compaction when the temperature was higher, and this reduction is less pronounced in the mixes manufactured with the gyratory compactor. Mixtures with additives tend to reduce the module, except paraffin.This paper is based on the results for the Fenix Project. The development of the Fenix Project was possible thanks to the financial contribution of the Center for Technological and Industrial Development (CDTI) within the framework of the Ingenio 2010 programme, through the CENIT Programme