6,755 research outputs found
Parallel line raster eliminates ambiguities in reading timing of pulses less than 500 microseconds apart
Parallel horizontal line raster is used for precision timing of events occurring less than 500 microseconds apart for observation of hypervelocity phenomena. The raster uses a staircase vertical deflection and eliminates ambiguities in reading timing of pulses close to the end of each line
Burst annealing of high temperature GaAs solar cells
One of the major limitations of solar cells in space power systems is their vulnerability to radiation damage. One solution to this problem is to periodically heat the cells to anneal the radiation damage. Annealing was demonstrated with silicon cells. The obstacle to annealing of GaAs cells was their susceptibility to thermal damage at the temperatures required to completely anneal the radiation damage. GaAs cells with high temperature contacts and encapsulation were developed. The cells tested are designed for concentrator use at 30 suns AMO. The circular active area is 2.5 mm in diameter for an area of 0.05 sq cm. Typical one sun AMO efficiency of these cells is over 18 percent. The cells were demonstrated to be resistant to damage after thermal excursions in excess of 600 C. This high temperature tolerance should allow these cells to survive the annealing of radiation damage. A limited set of experiments were devised to investigate the feasibility of annealing these high temperature cells. The effect of repeated cycles of electron and proton irradiation was tested. The damage mechanisms were analyzed. Limitations in annealing recovery suggested improvements in cell design for more complete recovery. These preliminary experiments also indicate the need for further study to isolate damage mechanisms. The primary objective of the experiments was to demonstrate and quantify the annealing behavior of high temperature GaAs cells. Secondary objectives were to measure the radiation degradation and to determine the effect of repeated irradiation and anneal cycles
Solitary Waves in Discrete Media with Four Wave Mixing
In this paper, we examine in detail the principal branches of solutions that
arise in vector discrete models with nonlinear inter-component coupling and
four wave mixing. The relevant four branches of solutions consist of two single
mode branches (transverse electric and transverse magnetic) and two mixed mode
branches, involving both components (linearly polarized and elliptically
polarized). These solutions are obtained explicitly and their stability is
analyzed completely in the anti-continuum limit (where the nodes of the lattice
are uncoupled), illustrating the supercritical pitchfork nature of the
bifurcations that give rise to the latter two, respectively, from the former
two. Then the branches are continued for finite coupling constructing a full
two-parameter numerical bifurcation diagram of their existence. Relevant
stability ranges and instability regimes are highlighted and, whenever
unstable, the solutions are dynamically evolved through direct computations to
monitor the development of the corresponding instabilities. Direct connections
to the earlier experimental work of Meier et al. [Phys. Rev. Lett. {\bf 91},
143907 (2003)] that motivated the present work are given.Comment: 13 pages, 10 figure
Petroleum hydrocarbons in fresh waters: a preliminary desk study and bibliography
A literature survey was carried out into the effects of petroleum hydrocarbons in freshwater, from the toxicity, biodegradability and concentration aspects. It was supplemented by a selective search on hydrocarbons in the marine environment for comparison. The aim was to determine the major inputs of these hydrocarbons, their accumulation, effects and fate in freshwaters. The search was confined to the period 1965-1978. The bibliography contains 390 references, divided by subject
Why Henry James still matters
For many of us, lockdown has meant an even more intense immersion in the media whirl of rolling news and politics, an addictive torrent of speculation, opinion and partial revelation, appealing to the prejudices of one side or another and manipulatively subjecting us to the temptations of âconfirmation biasâ. But we can also come to feel a revulsion from so fast-shifting, so unrewardingly strident a world, and seek a connection with wiser, more equivocal, durably nourishing voicesâwithout wanting to retreat too much into old fixed categories, or become in T.S. Eliotâs phrase âassured of certain certaintiesâ. Not everyone will find their much-needed haven in the work of Henry James, perhaps. But if we want a highly intelligent, deeply felt, psychologically astute, ironically self-questioning, magnificently eloquent body of work to challenge and repay a sustained effort of attention on our partâwell, you couldnât do better
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Glucocorticoid therapy for adrenal insufficiency: nonadherence, concerns and dissatisfaction with information
Objective: Appropriate selfâmanagement of glucocorticoid therapy (GC) is crucial for patients with adrenal insufficiency (AI). We aimed to describe patientsâ selfâreported nonadherence to GC, evaluate perceived doubts about need for GC, concerns about adverse effects, and dissatisfaction with information received about GC.
Design: Crossâsectional survey.
Patients: Patients prescribed GC for AI (n = 81) from five European countries.
Measurements: Online survey including the Medication Adherence Report Scale (MARS), Beliefs about Medicines Questionnaire© (BMQ Specific, adapted for AI) and Satisfaction with Information about Medicines Scale© (Prof Rob Horne; SIMS).
Results: Most patients (85·2%) reported a degree of nonadherence to GC. The most frequent types of nonadherence concerned changing the timing of GC doses, for example taking a dose later in the day than advised (37·0%). Few patients doubted their personal need for daily GC, but most reported high concerns about GC including potential weight gain (50·6%), osteoporosis (53·6%) and the continuing risk of adrenal crisis (50·6%). Dissatisfaction with information about GC was frequent, with participants particularly dissatisfied with the amount of information they had received about potential problems with GC. People who expressed dissatisfaction with information about GC, and concerns about its adverse effects were also more likely to report nonadherence (P < 0·05).
Conclusions: Nonadherence to treatment, concerns about potential adverse effects and dissatisfaction with the information provided about treatment were frequently reported by this European sample of AI patients. Many AI patients may need additional information about their GC and support to address concerns about GC and facilitate adherence
Heating and cooling of coronal loops with turbulent suppression of parallel heat conduction
Using the "enthalpy-based thermal evolution of loops" (EBTEL) model, we
investigate the hydrodynamics of the plasma in a flaring coronal loop in which
heat conduction is limited by turbulent scattering of the electrons that
transport the thermal heat flux. The EBTEL equations are solved analytically in
each of the two (conduction-dominated and radiation-dominated) cooling phases.
Comparison of the results with typical observed cooling times in solar flares
shows that the turbulent mean free-path lies in a range
corresponding to a regime in which classical (collision-dominated) conduction
plays at most a limited role. We also consider the magnitude and duration of
the heat input that is necessary to account for the enhanced values of
temperature and density at the beginning of the cooling phase and for the
observed cooling times. We find through numerical modeling that in order to
produce a peak temperature ~K and a 200~s cooling time
consistent with observations, the flare heating profile must extend over a
significant period of time; in particular, its lingering role must be taken
into consideration in any description of the cooling phase. Comparison with
observationally-inferred values of post-flare loop temperatures, densities, and
cooling times thus leads to useful constraints on both the magnitude and
duration of the magnetic energy release in the loop, as well as on the value of
the turbulent mean free-path .Comment: 16 pages, 4 figures, to be published in The Astrophysical Journa
Bible Study Groups As A Means Of Christian Nurture In The Brazilian Culture
It is the purpose of this report to present the findings of the author\u27s study with respect to possible adaptations of certain principles and procedures of group Bible study to Brazilian Seventh- day Adventist Church members as a means of Christian nurture.
(No Abstract
The Effect of Different Styles of Mutes upon the Intensity and the Harmonic Structure of the Violin Tone
The general problem was to study the effect of variations of the violin bridge upon intensity and timbre. In this paper a report will be given of the results with regard to the addition of different mutes to the bridge. In general the results indicate that (1) muting reduces energy in the upper partials, but that the different mutes are not uniformly selective throughout all the partials, and (2) all mutes do not necessarily reduce the total intensity of all strings proportionately
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