2,065 research outputs found

    Ellipsometric measurements of the refractive indices of linear alkylbenzene and EJ-301 scintillators from 210 to 1000 nm

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    We report on ellipsometric measurements of the refractive indices of LAB-PPO, Nd-doped LAB-PPO and EJ-301 scintillators to the nearest +/-0.005, in the wavelength range 210-1000 nm.Comment: 7 pages, 4 figure

    Accurate first principles detailed balance determination of Auger recombination and impact ionization rates in semiconductors

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    The technologically important problem of predicting Auger recombination lifetimes in semiconductors is addressed by means of a fully first--principles formalism. The calculations employ highly precise energy bands and wave functions provided by the full--potential linearized augmented plane wave (FLAPW) code based on the screened exchange local density approximation. The minority carrier Auger lifetime is determined by two closely related approaches: \emph{i}) a direct evaluation of the Auger rates within Fermi's Golden Rule, and \emph{ii}) an indirect evaluation, based on a detailed balance formulation combining Auger recombination and its inverse process, impact ionization, in a unified framework. Calculated carrier lifetimes determined with the direct and indirect methods show excellent consistency \emph{i}) between them for nn-doped GaAs and \emph{ii}%) with measured values for GaAs and InGaAs. This demonstrates the validity and accuracy of the computational formalism for the Auger lifetime and indicates a new sensitive tool for possible use in materials performance optimization.Comment: Phys. Rev. Lett. accepte

    Magnetic field imaging with atomic Rb vapor

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    We demonstrate the possibility of dynamic imaging of magnetic fields using electromagnetically induced transparency in an atomic gas. As an experimental demonstration we employ an atomic Rb gas confined in a glass cell to image the transverse magnetic field created by a long straight wire. In this arrangement, which clearly reveals the essential effect, the field of view is about 2 x 2 mm^2 and the field detection uncertainty is 0.14 mG per 10 um x 10 um image pixel.Comment: 4 pages, 3 figure

    Anaesthesia for a morbidly obese patient with schizophrenia and intellectual disability

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    We report the case of a morbidly obese woman with schizophrenia and intellectual disability who underwent dental treatment using general anaesthesia. The 38-year-old patient was 156 cm tall and weighed 140 kg, with a body mass index of 57.5 kg.m-2. Her developmental age was less than five or six years. She had been taking several antipsychotic agents, including haloperidol. Tracheal intubation was performed smoothly and anaesthesia was maintained uneventfully using propofol and remifentanil.This case demonstrates that the method of general anaesthesia presented here can be used safely in managing patients with these kinds of disabilities

    Impact ionization in GaAs: a screened exchange density functional approach

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    Results are presented of a fully ab-initio calculation of impact ionization rates in GaAs within the density functional theory framework, using a screened-exchange formalism and the highly precise all-electron full-potential linearized augmented plane wave (FLAPW) method. The calculated impact ionization rates show a marked orientation dependence in {\bf k} space, indicating the strong restrictions imposed by the conservation of energy and momentum. This anisotropy diminishes as the impacting electron energy increases. A Keldysh type fit performed on the energy-dependent rate shows a rather soft edge and a threshold energy greater than the direct band gap. The consistency with available Monte Carlo and empirical pseudopotential calculations shows the reliability of our approach and paves the way to ab-initio calculations of pair production rates in new and more complex materials.Comment: 11 pages, 4 figures, Submitted to Phys. Rev.

    General anaesthesia with and without intubation for patients with Cornelia de Lange syndrome

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    We present the use of different methods of general anaesthesia in two patients with Cornelia de Lange syndrome and its contribution to the patients’ oral health.Case 1: The patient was a 22-year-old woman with Cornelia de Lange syndrome who underwent dental treatment under general anaesthesia. She exhibited the physical characteristics of Cornelia de Lange syndrome, including a small mouth, thin lips, short limbs, stiffness of joints and intellectual disability. General anaesthesia without intubation was performed safely eight times. No other complications except hypersensitivity to hypnotic agents were observed.Case 2: The patient was a 10-year-old boy with Cornelia de Lange syndrome who underwent dental treatment under general anaesthesia. He had a history and symptoms of obstructive airway disorders in addition to showing physical characteristics of the syndrome similar to those seen in Case 1. General anaesthesia with nasal intubation was performed safely twice. Computed tomography (CT) of his head and neck produced unremarkable results. These cases demonstrate that both general anaesthesia with and without nasal intubation can be safely used in managing individuals with Cornelia de Lange syndrome during dental treatment.Keywords: general anaesthesia; Cornelia de Lange syndrome; dental treatmen

    Nitrogen doping of TiO2 photocatalyst forms a second eg state in the Oxygen (1s) NEXAFS pre-edge

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    Close inspection of the pre-edge in oxygen near-edge x-ray absorption fine structure spectra of single step, gas phase synthesized titanium oxynitride photocatalysts with 20 nm particle size reveals an additional eg resonance in the VB that went unnoticed in previous TiO2 anion doping studies. The relative spectral weight of this Ti(3d)-O(2p) hybridized state with respect to and located between the readily established t2g and eg resonances scales qualitatively with the photocatalytic decomposition power, suggesting that this extra resonance bears co-responsibility for the photocatalytic performance of titanium oxynitrides at visible light wavelengths

    Social Preference Tests in Zebrafish: A Systematic Review

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    The use of animal models in biology research continues to be necessary for the development of new technologies and medicines, and therefore crucial for enhancing human and animal health. In this context, the need to ensure the compliance of research with the principles Replacement, Reduction and Refinement (the 3 Rs), which underpin the ethical and human approach to husbandry and experimental design, has become a central issue. The zebrafish (Danio rerio) is becoming a widely used model in the field of behavioral neuroscience. In particular, studying zebrafish social preference, by observing how an individual fish interacts with conspecifics, may offer insights into several neuropsychiatric and neurodevelopmental disorders. The main aim of this review is to summarize principal factors affecting zebrafish behavior during social preference tests. We identified three categories of social research using zebrafish: studies carried out in untreated wild-type zebrafish, in pharmacologically treated wild-type zebrafish, and in genetically engineered fish. We suggest guidelines for standardizing social preference testing in the zebrafish model. The main advances gleaned from zebrafish social behavior testing are discussed, together with the relevance of this method to scientific research, including the study of behavioral disorders in humans. The authors stress the importance of adopting an ethical approach that considers the welfare of animals involved in experimental procedures. Ensuring a high standard of animal welfare is not only good for the animals, but also enhances the quality of our science
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