156 research outputs found

    Imaging transverse electron focusing in semiconducting heterostructures with spin-orbit coupling

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    Transverse electron focusing in two-dimensional electron gases (2DEGs) with strong spin-orbit coupling is revisited. The transverse focusing is related to the transmission between two contacts at the edge of a 2DEG when a perpendicular magnetic field is applied. Scanning probe microscopy imaging techniques can be used to study the electron flow in these systems. Using numerical techniques we simulate the images that could be obtained in such experiments. We show that hybrid edge states can be imaged and that the outgoing flux can be polarized if the microscope tip probe is placed in specific positions.Comment: Contribution to the Book/Proceedings of the PITP Les Houches School on "Quantum Magnetism" held on June, 2006. Final forma

    Status report on emerging photovoltaics

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    \ua9 2023 Society of Photo-Optical Instrumentation Engineers (SPIE).This report provides a snapshot of emerging photovoltaic (PV) technologies. It consists of concise contributions from experts in a wide range of fields including silicon, thin film, III-V, perovskite, organic, and dye-sensitized PVs. Strategies for exceeding the detailed balance limit and for light managing are presented, followed by a section detailing key applications and commercialization pathways. A section on sustainability then discusses the need for minimization of the environmental footprint in PV manufacturing and recycling. The report concludes with a perspective based on broad survey questions presented to the contributing authors regarding the needs and future evolution of PV

    Engineering Cloud-based Applications: Towards an Application Lifecycle

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    The adoption of cloud computing by organizations of all sizes and types in the recent years has created multiple opportunities and challenges for the development of software to be used in this environment. In this work-in-progress paper, the focus is on the latter part, providing a view on the main research challenges that are created for software engineering by cloud computing. These challenges stem from the inherent characteristics of the cloud computing paradigm, and require a multi-dimensional approach to address them. Towards this goal, a lifecycle for cloud-based applications is presented, as the foundation for further work in the area

    Busulphan-Cyclophosphamide Cause Endothelial Injury, Remodeling of Resistance Arteries and Enhanced Expression of Endothelial Nitric Oxide Synthase

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    Stem cell transplantation (SCT) is a curative treatment for malignant and non malignant diseases. However, transplantation-related complications including cardiovascular disease deteriorate the clinical outcome and quality of life. We have investigated the acute effects of conditioning regimen on the pharmacology, physiology and structure of large elastic arteries and small resistance-sized arteries in a SCT mouse model. Mesenteric resistance arteries and aorta were dissected from Balb/c mice conditioned with busulphan (Bu) and cyclophosphamide (Cy). In vitro isometric force development and pharmacology, in combination with RT-PCR, Western blotting and electron microscopy were used to study vascular properties. Compared with controls, mesenteric resistance arteries from the Bu-Cy group had larger internal circumference, showed enhanced endothelium mediated relaxation and increased expression of endothelial nitric oxide synthase (eNOS). Bu-Cy treated animals had lower mean blood pressure and signs of endothelial injury. Aortas of treated animals had a higher reactivity to noradrenaline. We conclude that short-term consequences of Bu-Cy treatment divergently affect large and small arteries of the cardiovascular system. The increased noradrenaline reactivity of large elastic arteries was not associated with increased blood pressure at rest. Instead, Bu-Cy treatment lowered blood pressure via augmented microvascular endothelial dependent relaxation, increased expression of vascular eNOS and remodeling toward a larger lumen. The changes in the properties of resistance arteries can be associated with direct effects of the compounds on vascular wall or possibly indirectly induced via altered translational activity associated with the reduced hematocrit and shear stress. This study contributes to understanding the mechanisms that underlie the early effects of conditioning regimen on resistance arteries and may help in designing further investigations to understand the late effects on vascular system

    New Pharmacological Agents to Aid Smoking Cessation and Tobacco Harm Reduction: What has been Investigated and What is in the Pipeline?

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    A wide range of support is available to help smokers to quit and aid attempts at harm reduction, including three first-line smoking cessation medications: nicotine replacement therapy, varenicline and bupropion. Despite the efficacy of these, there is a continual need to diversify the range of medications so that the needs of tobacco users are met. This paper compares the first-line smoking cessation medications to: 1) two variants of these existing products: new galenic formulations of varenicline and novel nicotine delivery devices; and 2) twenty-four alternative products: cytisine (novel outside of central and eastern Europe), nortriptyline, other tricyclic antidepressants, electronic cigarettes, clonidine (an anxiolytic), other anxiolytics (e.g. buspirone), selective 5-hydroxytryptamine (5-HT) reuptake inhibitors, supplements (e.g. St John’s wort), silver acetate, nicobrevin, modafinil, venlafaxine, monoamine oxidase inhibitors (MAOI), opioid antagonist, nicotinic acetylcholine receptors (nAChR) antagonists, glucose tablets, selective cannabinoid type 1 receptor antagonists, nicotine vaccines, drugs that affect gamma-aminobutyric acid (GABA) transmission, drugs that affect N-methyl-D-aspartate receptors (NMDA), dopamine agonists (e.g. levodopa), pioglitazone (Actos; OMS405), noradrenaline reuptake inhibitors, and the weight management drug lorcaserin. Six criteria are used: relative efficacy, relative safety, relative cost, relative use (overall impact of effective medication use), relative scope (ability to serve new groups of patients), and relative ease of use (ESCUSE). Many of these products are in the early stages of clinical trials, however, cytisine looks most promising in having established efficacy and safety and being of low cost. Electronic cigarettes have become very popular, appear to be efficacious and are safer than smoking, but issues of continued dependence and possible harms need to be considered

    A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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    Ensemble monte carlo study of nonequilibrium carrier dynamics in photo-excited p-i-n, structures

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    Light scattering from conduction electrons (or from valence holes) can give information on the time-resolved velocity distribution of nonequilibrium carriers. The experimental approach utilizes, e.g., Raman scattering from the single particles to ascertain the velocity distribution. Calculation of the distribution function through an ensemble Monte Carlo technique allows a comparison between the experiment and theory. Here, this is demonstrated with studies of a GaAs p-i-n structure embedded within cladding AlAs layers. The calculations are compared with experimental results that have recently been published on the same structure. For time scales of several hundred femtoseconds, the hot carrier transport that is probed by the single-particle Raman scattering is dominated by the transport in the Gamma valley, and overshoot velocities 4-5 x 10(5) cm/sec are observed

    ENSEMBLE MONTE-CARLO SIMULATION OF RAMAN-SCATTERING IN GAAS

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    A picosecond laser excited GaAs p-i-n structure is studied using an ensemble Monte Carlo method to determine the temporal and spatial evolution of the hot electron distribution function. The experimental set-up we simulate is a novel method based on Raman scattering of light from the electrons to measure the drift velocity of electrons in GaAs at high electric fields. It is observed that the simulation agrees with the experimental results, however, the measured velocity is actually averaged over the time evolution of the spatial distribution of the Raman probe in the sample and underestimates the average velocity of electrons over the pulselength excited in the (Gamma) conduction band of a 1.909 eV laser pulse, which is calculated to be in the order of 8.5 X 107 cm/sec for fields of 25 kV/cm at a temperature of 77 K

    Quantum transport simulation of the DOS function, self-consistent fields and mobility in MOS inversion layers

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    We describe a simulation of the self-consistent fields and mobility in (100) Si-inversion layers for arbitrary inversion charge densities and temperatures. A nonequilibrium Green's functions formalism is employed for the state broadening and conductivity. The subband structure of the inversion layer electrons is calculated self-consistently by simultaneously solving the Schrodinger, Poisson and Dyson equations, The self-energy contributions from the various scattering mechanisms are calculated within the self-consistent Born approximation. Screening is treated within RPA, Simulation results suggest that the proposed theoretical model gives mobilities which are in excellent agreement with the experimental data
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