757 research outputs found

    Maximizing Credibility and Accountability in Qualitative Data Collection and Data Analysis: A Social Work Research Case Example

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    A case example demonstrates the use of qualitative methods of data collection and data analysis that balance structure and flexibility, and maximize credibility and accountability. Data collection methods use sensitizing concepts from past research and theory and allow for the discovery of respondent-defined meanings. This approach comparatively analyzes cases, structures and documents data analysis steps, and utilizes external reviewers of case materials. The development and use of methods that maximize credibility and accountability will increase their acceptance among social workers and will benefit the profession by adding empirically-grounded depth and insight to its knowledge base

    Comparison of oral iron and injectable iron for the prevention of iron deficiency anemia in baby pigs

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    One of two oral iron compounds or an injectable iron (100 mg iron per treatment) were administered to pigs on d 1 and 15 postfarrowing, and they were compared with untreated littermates. There was no significant difference between the pigs receiving the oral iron and the negative controls in serum iron or total iron binding capacity. Pigs that received iron by injection had higher serum iron and packed cell volume and a lower total iron binding capacity compared with pigs given oral iron or untreated controls.; Swine Day, Manhattan, KS, November 19, 199

    16 x 25 Ge:Ga Detector Arrays for FIFI LS

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    We are developing two-dimensional 16 x 25 pixel detector arrays of both unstressed and stressed Ge:Ga photoconductive detectors for far-infrared astronomy from SOFIA. The arrays, based on earlier 5 x 5 detector arrays used on the KAO, will be for our new instrument, the Far Infrared Field Imaging Line Spectrometer (FIFI LS). The unstressed Ge:Ga detector array will cover the wavelength range from 40 to 120 microns, and the stressed Ge:Ga detector array from 120 to 210 microns. The detector arrays will be operated with multiplexed integrating amplifiers with cryogenic readout electronics located close to the detector arrays. The design of the stressed detector array and results of current measurements on several prototype 16 pixel linear arrays are reported. They demonstrate the feasibility of the current concept. ***This paper does not include Figures due to astro-ph size limitations. Please download entire file at http://fifi-ls.mpe-garching.mpg.de/spie.det.ps.gz ***Comment: 8 pages, SPIE Proceedings, Astronomical Telescopes and Instrumentation 200

    Cryogenic light detectors with enhanced performance for rare events physics

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    We have developed and tested a new way of coupling bolometric light detectors to scintillating crystal bolometers based upon simply resting the light detector on the crystal surface, held in position only by gravity. This straightforward mounting results in three important improvements: (1) it decreases the amount of non-active materials needed to assemble the detector, (2) it substantially increases the light collection efficiency by minimizing the light losses induced by the mounting structure, and (3) it enhances the thermal signal induced in the light detector thanks to the extremely weak thermal link to the thermal bath. We tested this new technique with a 16 cm2^2 Ge light detector with thermistor readout sitting on the surface of a large TeO2_2 bolometer. The light collection efficiency was increased by greater than 50\% compared to previously tested alternative mountings. We obtained a baseline energy resolution on the light detector of 20~eV RMS that, together with increased light collection, enabled us to obtain the best α\alpha vs ÎČ/Îł\beta/\gamma discrimination ever obtained with massive TeO2_2 crystals. At the same time we achieved rise and decay times of 0.8 and 1.6 ms, respectively. This superb performance meets all of the requirements for the CUPID (CUORE Upgrade with Particle IDentification) experiment, which is a 1-ton scintillating bolometer follow up to CUORE.Comment: 6 pages, 4 figure

    Formation of diluted III–V nitride thin films by N ion implantation

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    iluted III–Nₓ–V₁ˍₓ alloys were successfully synthesized by nitrogen implantation into GaAs,InP, and AlyGa1−yAs. In all three cases the fundamental band-gap energy for the ion beam synthesized III–Nₓ–V₁ˍₓ alloys was found to decrease with increasing N implantation dose in a manner similar to that observed in epitaxially grownGaNₓAs1−x and InNₓP₁ˍₓalloys. In GaNₓAs₁ˍₓ the highest value of x (fraction of “active” substitutional N on As sublattice) achieved was 0.006. It was observed that NAs is thermally unstable at temperatures higher than 850 °C. The highest value of x achieved in InNₓP₁ˍₓ was higher, 0.012, and the NP was found to be stable to at least 850 °C. In addition, the N activation efficiency in implantedInNₓP₁ˍₓ was at least a factor of 2 higher than that in GaNₓAs₁ˍₓ under similar processing conditions. AlyGa1−yNₓAs₁ˍₓ had not been made previously by epitaxial techniques. N implantation was successful in producing AlyGa1−yNₓAs₁ˍₓalloys. Notably, the band gap of these alloys remains direct, even above the value of y (y>0.44) where the band gap of the host material is indirect.This work was supported by the ‘‘Photovoltaic Materials Focus Area’’ in the DOE Center of Excellence for the Synthesis and Processing of Advanced Materials, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences under U.S. Department of Energy Contract No. DE-ACO3-76SF00098. The work at UCSD was partially supported by Midwest Research Institute under subcontractor No. AAD-9-18668-7 from NREL

    TeO2_2 bolometers with Cherenkov signal tagging: towards next-generation neutrinoless double beta decay experiments

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    CUORE, an array of 988 TeO2_2 bolometers, is about to be one of the most sensitive experiments searching for neutrinoless double-beta decay. Its sensitivity could be further improved by removing the background from α\alpha radioactivity. A few years ago it has been pointed out that the signal from ÎČ\betas can be tagged by detecting the emitted Cherenkov light, which is not produced by α\alphas. In this paper we confirm this possibility. For the first time we measured the Cherenkov light emitted by a CUORE crystal, and found it to be 100 eV at the QQ-value of the decay. To completely reject the α\alpha background, we compute that one needs light detectors with baseline noise below 20 eV RMS, a value which is 3-4 times smaller than the average noise of the bolometric light detectors we are using. We point out that an improved light detector technology must be developed to obtain TeO2_2 bolometric experiments able to probe the inverted hierarchy of neutrino masses.Comment: 5 pages, 4 figures. Added referee correction

    Debris disks around Sun-like stars

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    We have observed nearly 200 FGK stars at 24 and 70 microns with the Spitzer Space Telescope. We identify excess infrared emission, including a number of cases where the observed flux is more than 10 times brighter than the predicted photospheric flux, and interpret these signatures as evidence of debris disks in those systems. We combine this sample of FGK stars with similar published results to produce a sample of more than 350 main sequence AFGKM stars. The incidence of debris disks is 4.2% (+2.0/-1.1) at 24 microns for a sample of 213 Sun-like (FG) stars and 16.4% (+2.8/-2.9) at 70 microns for 225 Sun-like (FG) stars. We find that the excess rates for A, F, G, and K stars are statistically indistinguishable, but with a suggestion of decreasing excess rate toward the later spectral types; this may be an age effect. The lack of strong trend among FGK stars of comparable ages is surprising, given the factor of 50 change in stellar luminosity across this spectral range. We also find that the incidence of debris disks declines very slowly beyond ages of 1 billion years.Comment: ApJ, in pres
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