63 research outputs found
Design, calibration, and performance of the MINERvA detector
The MINERvA(6) experiment is designed to perform precision studies of neutrino-nucleus scattering using nu(mu) and (nu) over bar (mu) neutrinos incident at 1-20 GeV in the NuMI beam at Fermilab. This article presents a detailed description of the MINERvA detector and describes the ex situ and in situ techniques employed to characterize the detector and monitor its performance. The detector is composed of a finely segmented scintillator-based inner tracking region surrounded by electromagnetic and hadronic sampling calorimetry. The upstream portion of the detector includes planes of graphite, iron and lead interleaved between tracking planes to facilitate the study of nuclear effects in neutrino interactions. Observations concerning the detector response over sustained periods of running are reported. The detector design and methods of operation have relevance to future neutrino experiments in which segmented scintillator tracking is utilized. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/)
Visual impairment from fibrous dysplasia in a middle-aged African man: a case report
<p>Abstract</p> <p>Introduction</p> <p>Fibrous dysplasia is a benign tumour of the bones and is a disease of unknown aetiology. This report discusses a case of proptosis and visual deterioration with associated bony mass involving the right orbit.</p> <p>Case presentation</p> <p>A 32-year-old Nigerian man of Yoruba ethnic origin presented to the eye clinic of our hospital with right-eye proptosis and visual deterioration of 7-year duration. Presentation was preceded by a history of trauma. Proptosis was preceded by trauma but was non-pulsatile with no thrill or bruit but was associated with bony orbital mass. The patient reported no weight loss. Examination of his right eye showed visual acuity of 6/60 with relative afferent pupillary defect. Fundal examination revealed optic atrophy. Computed tomography showed an expansile bony mass involving all the walls of the orbit. The bony orbital mass was diagnosed histologically as fibrous dysplasia. Treatment included orbital exploration and orbital shaping to create room for the globe and relieve pressure on the optic nerve.</p> <p>Conclusion</p> <p>Fibrous dysplasia should be considered in the differential diagnosis of slowly developing proptosis with associated visual loss in young adults.</p
Roadmap on dynamics of molecules and clusters in the gas phase
This roadmap article highlights recent advances, challenges and future prospects in studies of the dynamics of molecules and clusters in the gas phase. It comprises nineteen contributions by scientists with leading expertise in complementary experimental and theoretical techniques to probe the dynamics on timescales spanning twenty order of magnitudes, from attoseconds to minutes and beyond, and for systems ranging in complexity from the smallest (diatomic) molecules to clusters and nanoparticles. Combining some of these techniques opens up new avenues to unravel hitherto unexplored reaction pathways and mechanisms, and to establish their significance in, e.g. radiotherapy and radiation damage on the nanoscale, astrophysics, astrochemistry and atmospheric science
Competitive Oxygen Evolution in Acid Electrolyte Catalyzed at Technologically Relevant Electrodes Painted with Nanoscale RuO<sub>2</sub>
Using
a solution-based, non−line-of sight synthesis, we electrolessly
deposit ultrathin films of RuO<sub>2</sub> (“nanoskins”)
on planar and 3D substrates and benchmark their activity and stability
for oxygen-evolution reaction (OER) in acid electrolyte under device-relevant
conditions. When an electrically contiguous ∼9 nm thick RuO<sub>2</sub> nanoskin is expressed on commercially available, insulating
SiO<sub>2</sub> fiber paper, the RuO<sub>2</sub>@SiO<sub>2</sub> electrode
exhibits high current density at low overpotential (10 mA cm<sup>–2</sup> @ η = 280 mV), courtesy of a catalyst amplified in 3D; however,
the mass-normalized activity falls short of that achieved for films
deposited on planar, metallic substrates (Ti foil). By wrapping the
fibers with a <100 nm thick graphitic carbon layer prior to RuO<sub>2</sub> deposition (RuO<sub>2</sub>@C@SiO<sub>2</sub>), we retain
the high mass activity of the RuO<sub>2</sub> (40–60 mA mg<sup>–1</sup> @ η = 330 mV) and preserve the desirable macroscale
properties of the 3D scaffold: porous, lightweight, flexible, and
inexpensive. The RuO<sub>2</sub>@C@SiO<sub>2</sub> anodes not only
achieve the 10 mA cm<sup>–2</sup> figure of merit at a low
overpotential (η = ∼270 mV), but more importantly they
do so while (1) minimizing the mass of catalyst needed to achieve
this metric, (2) incorporating the catalyst into a practical electrode
design, and (3) improving the long-term stability of the catalyst.
Our best-performing anodes achieve state-of-the-art or better performance
on the basis of area and mass, and do so with a catalyst density 300–580×
less than that of bulk RuO<sub>2</sub>. By limiting the oxidizing
potential required to evolve O<sub>2</sub> at the electrode, even
at 10 mA cm<sup>–2</sup>, we achieve stable activity for 100+
h
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