31,788 research outputs found

    Outgassing, Temperature Gradients and the Radiometer Effect in LISA: A Torsion Pendulum Investigation

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    Thermal modeling of the LISA gravitational reference sensor (GRS) includes such effects as outgassing from the proof mass and its housing and the radiometer effect. Experimental data in conditions emulating the LISA GRS are required to confidently predict the GRS performance. Outgassing and the radiometer effect are similar in characteristics and are difficult to decouple experimentally. The design of our torsion balance allows us to investigate differential radiation pressure, the radiometer effect, and outgassing on closely separated conducting surfaces with high sensitivity. A thermally controlled split copper plate is brought near a freely hanging plate-torsion pendulum.We have varied the temperature on each half of the copper plate and have measured the resulting forces on the pendulum. We have determined that to first order the current GRS model for the radiometer effect, outgassing, and radiation pressure are mostly consistent with our torsion balance measurements and therefore these thermal effects do not appear to be a large hindrance to the LISA noise budget. However, there remain discrepancies between the predicted dependence of these effects on the temperature of our apparatus.Comment: 6th International LISA Symposiu

    Cowden syndrome - Diagnostic skin signs

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    Cowden syndrome is a rare autosomal dominant familial cancer syndrome with a high risk of breast cancer. The most important clinical features include carcinomas of the breast and thyroid, and hamartomatous polyps of the gastrointestinal tract. There are characteristic mucocutaneous features which allow early recognition of the disease and are generally present before internal malignancies develop. We report on a woman in whom the diagnosis of Cowden syndrome was first made after she had been treated for both breast cancer and melanoma. Copyright (C) 2001 S. KargerAG, Basel

    Spin Hall effect and Weak Antilocalization in Graphene/Transition Metal Dichalcogenide Heterostructures

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    We report on a theoretical study of the spin Hall Effect (SHE) and weak antilocal-ization (WAL) in graphene/transition metal dichalcogenide (TMDC) heterostructures, computed through efficient real-space quantum transport methods, and using realistic tight-binding models parametrized from ab initio calculations. The graphene/WS 2 system is found to maximize spin proximity effects compared to graphene on MoS 2 , WSe 2 , or MoSe 2 , with a crucial role played by disorder, given the disappearance of SHE signals in the presence of strong intervalley scattering. Notably, we found that stronger WAL effects are concomitant with weaker charge-to-spin conversion efficiency. For further experimental studies of graphene/TMDC heterostructures, our findings provide guidelines for reaching the upper limit of spin current formation and for fully harvesting the potential of two-dimensional materials for spintronic applications.Comment: This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Nano Letters, copyright\c{opyright}American Chemical Society after peer review. To access the final edited and published work see http://pubs.acs.org/articlesonrequest/AOR-c2pZ8WnmG7pcF4MIivj

    Meson and Baryon dispersion relations with Brillouin fermions

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    We study the dispersion relations of mesons and baryons built from Brillouin quarks on one N_f=2 gauge ensemble provided by QCDSF. For quark masses up to the physical strange quark mass, there is hardly any improvement over the Wilson discretization, if either action is link-smeared and tree-level clover improved. For quark masses in the range of the physical charm quark mass, the Brillouin action still shows a perfect relativistic behavior, while the Wilson action induces severe cut-off effects. As an application we determine the masses of the \Omega_c^0, \Omega_{cc}^+ and \Omega_{ccc}^{++} baryons on that ensemble.Comment: 16 pages, 9 figures, 4 tables; v2: one Reference added, matches published versio

    The Inverse Seesaw Mechanism in Noncommutative Geometry

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    In this publication we will implement the inverse Seesaw mechanism into the noncommutative framework on the basis of the AC-extension of the Standard Model. The main difference to the classical AC model is the chiral nature of the AC fermions with respect to a U(1) extension of the Standard Model gauge group. It is this extension which allows us to couple the right-handed neutrinos via a gauge invariant mass term to left-handed A-particles. The natural scale of these gauge invariant masses is of the order of 10^17 GeV while the Dirac masses of the neutrino and the AC-particles are generated dynamically and are therefore much smaller (ca. 1 GeV to 10^6 GeV). From this configuration a working inverse Seesaw mechanism for the neutrinos is obtained

    The cerebrovascular effects of adrenaline, noradrenaline and dopamine infusions under propofol and isoflurane anaesthesia in sheep

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    Publisher's copy made available with the permission of the publisher © Australian Society of AnaesthetistsInfusions of catecholamines are frequently administered to patients receiving propofol or isoflurane anaesthesia. Interactions between these drugs may affect regional circulations, such as the brain. The aim of this animal (sheep) study was to determine the effects of ramped infusions of adrenaline, noradrenaline (10, 20, 40 µg/min) and dopamine (10, 20, 40 µg/kg/min) on cerebral blood flow (CBF), intracranial pressure (ICP), cerebrovascular resistance (CVR) and cerebral metabolic rate for oxygen (CMRO₂). These measurements were made under awake physiological conditions, and during continuous propofol (15 mg/min) or 2% isoflurane anaesthesia. All three catecholamines significantly and equivalently increased mean arterial pressure from baseline in a dose-dependent manner in the three cohorts (P0.05). Under propofol (n=6) and isoflurane (n=6), all three catecholamines significantly increased CBF (P<0.001). Dopamine caused the greatest increase in CBF, and was associated with significant increases in ICP (awake: P<0.001; propofol P<0.05; isoflurane P<0.001) and CVR (isoflurane P<0.05). No significant changes in CMRO₂ were demonstrated. Under propofol and isoflurane anaesthesia, the cerebrovascular effects of catecholamines were significantly different from the awake, physiological state, with dopamine demonstrating the most pronounced effects, particularly under propofol. Dopamine-induced hyperaemia was associated with other cerebrovascular changes. In the presence of an equivalent effect on mean arterial pressure, the exaggerated cerebrovascular effects under anaesthesia appear to be centrally mediated, possibly induced by propofol- or isoflurane-dependent changes in blood-brain barrier permeability, thereby causing a direct influence on the cerebral vasculature.http://www.aaic.net.au/Article.asp?D=200205

    Identification of human papillomavirus DNA in cutaneous lesions of Cowden syndrome

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    Background: Cowden syndrome (CS) or multiple hamartoma syndrome is a cancer-associated genodermatosis inherited in an autosomal dominant pattern. One of the diagnostic criteria is facial papules which are felt to be trichilemmomas, benign hair follicle tumors, which some consider to be induced by human papillomavirus (HPV). Objective: To search for HPV in skin tumors, especially trichilemmomas, from patients with CS. Methods: Skin lesions from patients with CS were classified histologically. Each tumor was then analyzed for HPV DNA by polymerase chain reaction with different primer sets; positive amplicons were typed by direct sequencing. Results: Twenty-nine biopsies from 7 patients with CS were investigated. Only 2 of 29 tumors clinically suspected of being trichilemmomas were confirmed histologically. In addition, 3 sclerotic fibromas, also typical of CS, were found, as well as 1 sebaceous hyperplasia. The other 23 lesions showed histological features of HPV-induced tumors in various stages of development. HPV DNA was found in 19 of 29 cutaneous lesions. Tumors without any histological signs of HPV induction were negative for HPV DNA. Two tumors which were histologically classified as common warts contained HPV types 27 and 28. All the 17 other HPV types belong to the group of epidermodysplasia-verruciformis-associated types. Conclusions: The majority of cutaneous lesions in CS contain HPV DNA. They may have a variety of histological patterns. Trichilemmomas are not clinically distinctive and can be difficult to identify in CS patients. Copyright (C) 2003 S. Karger AG, Basel

    Spin transport in graphene/transition metal dichalcogenide heterostructures

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    Since its discovery, graphene has been a promising material for spintronics: its low spin-orbit coupling, negligible hyperfine interaction, and high electron mobility are obvious advantages for transporting spin information over long distances. However, such outstanding transport properties also limit the capability to engineer active spintronics, where strong spin-orbit coupling is crucial for creating and manipulating spin currents. To this end, transition metal dichalcogenides, which have larger spin-orbit coupling and good interface matching, appear to be highly complementary materials for enhancing the spin-dependent features of graphene while maintaining its superior charge transport properties. In this review, we present the theoretical framework and the experiments performed to detect and characterize the spin-orbit coupling and spin currents in graphene/transition metal dichalcogenide heterostructures. Specifically, we will concentrate on recent measurements of Hanle precession, weak antilocalization and the spin Hall effect, and provide a comprehensive theoretical description of the interconnection between these phenomena.Comment: 21 pages, 11 figures. This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Nano Letters, copyright\c{opyright}American Chemical Society after peer review. To access the final edited and published work see http://pubs.rsc.org/en/Content/ArticleLanding/2018/CS/C7CS00864
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