189 research outputs found
Different standards: engineersâ expectations and listener adoption of digital and FM radio broadcasting
As digital radio broadcasting enters its third decade of operation, few would argue that it has met all expectations expressed at the time of its launch in the mid-1990s. Observers are now more circumspect, with views divided on the pace of transition to an all-digital future. In exploring this mismatch between expectation and actuality, this article considers the introduction of FM radio from the 1950s. It too was expected to replace its forebear (AM) but, like digital radio, its adoption by listeners was slower than anticipated. An examination of published literature, in particular engineering and technical documents, reveals a number of similarities in the development of digital radio and FM. Assumptions about listenersâ needs and preferences appear to have been based on little actual audience research and, with continual reference in the literature to the supposed deficiencies of the predecessor technology, suggest an emphasis in decision making on the technical qualities of radio broadcasting over an appreciation of actual audience preferences
Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET
The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR
Relationship of edge localized mode burst times with divertor flux loop signal phase in JET
A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM
Control of Oxo-Group Functionalization and Reduction of the Uranyl Ion
yesUranyl complexes of a large, compartmental
N8-macrocycle adopt a rigid, âPacmanâ geometry that stabilizes
the UV oxidation state and promotes chemistry at a single
uranyl oxo-group. We present here new and straightforward
routes to singly reduced and oxo-silylated uranyl Pacman
complexes and propose mechanisms that account for the
product formation, and the byproduct distributions that are
formed using alternative reagents. Uranyl(VI) Pacman
complexes in which one oxo-group is functionalized by a
single metal cation are activated toward single-electron
reduction. As such, the addition of a second equivalent of a
Lewis acidic metal complex such as MgNâł2 (Nâł = N(SiMe3)2) forms a uranyl(V) complex in which both oxo-groups are Mg
functionalized as a result of MgâN bond homolysis. In contrast, reactions with the less Lewis acidic complex [Zn(Nâł)Cl] favor
the formation of weaker UâOâZn dative interactions, leading to reductive silylation of the uranyl oxo-group in preference to
metalation. Spectroscopic, crystallographic, and computational analysis of these reactions and of oxo-metalated products isolated
by other routes have allowed us to propose mechanisms that account for pathways to metalation or silylation of the exo-oxogroup
Strategies for Combating Climate Change in Drylands Agriculture: Synthesis of dialogues and evidence presented at the International Conference on Food Security in Dry Lands, Doha, Qatar, November, 2012.
The aim of this report is to examine the problem of changing climate patterns in dry land areas and its effect on rural populations and offer some practical solutions, as input the Conference of Conference of the Parties (COP18) United Nations Framework Convention on Climate Change (UNFCCC).
It has been prepared to inform government policy makers and agricultural planners in dryland countries, and development partners, of the issues at stake and present options available to reducing risk and increasing productivity of agriculture in drylands agricultural systems.
The information presented here comes from discussions at the International Conference on Food Security in Dry Lands, held in Doha, Qatar, on Nov 14-15, 2012. It is informed by the body of agricultural research produced by three authors of this report: CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS); ICARDA â The International Center for Agricultural Research in the Dry Areas; CGIAR Research Program on Dryland Systems.
The Doha conference brought together a large number of dryland government ministers with researchers, policy makers, donors, NGOs, farmersâ unions and private agribusiness enterprises to explore the challenge of increasing agricultural production in dry countries, under conditions of severe water scarcity and climate change.
The ministersâ recommendations, resulted in the Doha Declaration (see Annexe), which is taken forward on behalf of the Dry Lands to the 18th session of the Conference on Parties of the UN Conference of Parties of the Convention on Climate Change (COP 18), which opened in Doha in November 2012
Infrastructure and Readiness Team
This document represents the best opinion of CNA at the time of issue
Imaging of Neuralgic Amyotrophy in the Acute Phase.
INTRODUCTION/AIMS
Hourglass-like constrictions (HGCs) occur in neuralgic amyotrophy (NA), but the earliest time at which they can be recognized by imaging is poorly understood. We aimed to determine the prevalence of abnormal imaging findings in the acute phase of NA.
METHODS
Magnetic resonance neurography (MRN) and high-resolution ultrasound (US) examinations were performed at 5 sites. The investigation included 39 patients with acute NA who underwent imaging within 31âdays of symptom onset. Correlation between imaging and electromyography (EMG) findings was measured.
RESULTS
US was performed in 29 patients and MRN in 23; 16 patients underwent US only, 10 MRN only, and 13 had both. US and MRN showed nerve abnormalities within 1âmonth from NA onset in 90% of patients. HGCs were found in 74% (29/39) of the patients: 4 within 1âweek, 8 within 2âweeks, 5 within 3âweeks, and 12 within 4âweeks. The earliest HGC on US was found within 12âhours, and on MRN within 3âdays from symptom onset. MRN demonstrated a denervation edema pattern of affected muscles in 91% of the patients. The shortest time to observe an edema pattern on MRN was 8âdays. EMG was performed in 30 patients and revealed fibrillation potentials in affected muscles in 22 (73%). A denervation edema pattern on MRN was significantly associated with the presence of HGCs both on MRN and US, and with fibrillation potentials on EMG.
DISCUSSION
In the early phase of NA, US and MRN are useful diagnostic techniques for demonstrating nerve abnormalities. This article is protected by copyright. All rights reserved
Overview of erosionâdeposition diagnostic tools for the ITER-Like Wall in the JET tokamak
This paper presents scientific and technical issues related to the development of erosionâdeposition diagnostic tools for JET operated with the ITER-Like Wall: beryllium and tungsten marker tiles and several types of wall probes installed in the main chamber and in the divertor. Markers tiles are the standard limiter and divertor components additionally coated first with a thin sandwich of NiâBe and MoâW for, beryllium and tungsten markers, respectively. Both types of markers are embedded in regular arrays of limiter and divertor tiles. Coated WâBe probes are also inserted in the Be-covered Inconel cladding tiles on the central column. Other types of erosionâdeposition diagnostic tools are: rotating collectors, deposition traps, louver clips, quartz microbalance and mirrors for the First Mirror Test at JET for ITER. The specific role of these tools is discussed in detail
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