Showing papers by "David W. Johnson published in 1997"
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TL;DR: In this article, the effectiveness of a conflict resolution training program in an American, midwestern, middle school was examined, where participants were 198 students in Grades 6 through 9.
Abstract: The effectiveness of a conflict resolution training program in an American, midwestern, middle school was examined. The participants were 198 students in Grades 6 through 9. A pretest-posttest control-group experimental design was used. Those in the experimental group received 14 hr of training during a 25-min homeroom period. Significant differences between experimental and control groups occurred in knowledge of the negotiation procedure and ability to apply it to actual conflicts.
75 citations
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TL;DR: In this article, a new metastable binary compound and a series of new, metastable ternary crystalline compounds with the skutterudite crystal structure have been prepared through controlled crystallization of amorphous reaction intermediates formed by low-temperature interdiffusion of modulated elemental reactants.
Abstract: A new metastable binary compound and a series of new, metastable ternary crystalline compounds with the skutterudite crystal structure have been prepared through controlled crystallization of amorphous reaction intermediates formed by low-temperature interdiffusion of modulated elemental reactants. Discussed in this paper are La{sub 1-x}Fe{sub 4}Sb{sub 12}, FeSb{sub 3}, Hf{sub 1-x}Fe{sub 4}Sb{sub 12}, and Y{sub 1-x}Fe{sub 4}Sb{sub 12}. The amorphous reaction intermediate for each system crystallizes exothermically near 200 {degree}C forming the desired skutterudite structure. At temperatures above 500 {degree}C, they decompose exothermically forming a thermodynamically more stable mixture of binary compounds and elemental components. We propose that the desired compounds nucleate from the amorphous precursor because slow solid state diffusion rates hinder disproportionation into the more stable mix of binary compounds and elements. This general synthetic approach to prepare new metastable compounds give control of both the composition and structure of the product compounds. 15 refs., 6 figs., 2 tabs.
72 citations
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TL;DR: The effectiveness of a conflict-resolution program in a suburban secondary school in Canada was examined by as mentioned in this paper, where participants were 40 ninth-grade English students heterogeneous in academic ability.
Abstract: The effectiveness of a conflict-resolution program in a suburban secondary school in Canada was examined. Participants were 40 ninth-grade English students heterogeneous in academic ability. Students randomly assigned to the experimental condition received 9.5 hr of conflict-resolution training integrated into the study of literature. Those randomly assigned to the control condition studied the identical literature for 9.5 hr without conflict-resolution training. Significant differences between treatment groups were found in academic achievement, knowledge of and willingness to use the conflict-resolution procedure, and application of the procedure in conflicts.
60 citations
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TL;DR: IGF-I, an analog that binds to the IGF-I receptor but not to IGFBPs, provided a less potent stimulus for PTC growth compared with IGF-i, indicating that cell-associated IGFBP-3 facilitates the action of IGF- I on PTC.
54 citations
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TL;DR: The Tokamak Fusion Test Reactor (TFTR) has been operating safely and routinely with deuterium-tritium fuel for more than two years as discussed by the authors, achieving record breaking results.
54 citations
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TL;DR: In this paper, a series of stable and metastable rare earth element−iron antimonides, controlling both composition and structure using multilayer reactants, were synthesized and analyzed.
Abstract: We have synthesized a series of stable and metastable rare earth element−iron antimonides, controlling both composition and structure using multilayer reactants. The stable rare earth iron element antimonides have the filled skutterudite structure (LaFe4P12) with a stoichiometry of 1 for the rare earth element. The metastable rare earth element−iron antimonides could be prepared with the entire sequence of rare earth elements. The lattice parameters of these metastable compounds were always larger than those of the corresponding more stable analog, and the occupancy of the rare earth element cation was found to be less than 1. Reitveld analysis of Lu1-xFe4Sb12 suggests that the late rare earth element compounds have a new distorted filled skutterudite structure. Structural trends are discussed in terms of their potential use as thermoelectric materials.
45 citations
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37 citations
01 Jan 1997
36 citations
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TL;DR: One hundred seven freshman student athletes in 17 different women's and men's intercollegiate sports were required to attend evening study sessions and reported that they worked cooperatively on academic assignments and studied for tests primarily in cooperative learning groups.
Abstract: One hundred seven freshman student athletes in 17 different women's and men's intercollegiate sports were required to attend evening study sessions. The student athletes completed academic assignments and studied for tests primarily in cooperative learning groups. As gauges of the program's impact on the participants, 3 questionnaires were administered to a sample of 50 (25 women and 25 men). The respondents reported that (a) they worked cooperatively on academic assignments, (b) the program staff provided both academic and personal support while structuring and facilitating cooperative learning groups, and (c) they themselves were highly task oriented, confident of their academic ability, and involved in positive and supportive relationships with their fellow participants.
33 citations
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Princeton University1, University of Texas at Austin2, Oak Ridge National Laboratory3, University of Wisconsin-Madison4, New York University5, General Atomics6, Massachusetts Institute of Technology7, University of California, Irvine8, Lawrence Livermore National Laboratory9, Northrop Grumman Corporation10, University of California, Los Angeles11, Columbia University12, Chinese Academy of Sciences13, Los Alamos National Laboratory14
TL;DR: The Tokamak Fusion Test Reactor (TFTR) is a large tokamak which has performed experiments with 50:50 deuterium - tritium fuelled plasmas as discussed by the authors.
Abstract: The Tokamak Fusion Test Reactor (TFTR) is a large tokamak which has performed experiments with 50:50 deuterium - tritium fuelled plasmas. Since 1993, TFTR has produced about 1090 D - T plasmas using about 100 grams of tritium and producing about 1.6 GJ of D - T fusion energy. These plasmas have significant populations of 3.5 MeV alphas (the charged D - T fusion product). TFTR research has focused on alpha particle confinement, alpha driven modes, and alpha heating studies. Maximum D - T fusion power production has aided these studies, requiring simultaneously operation at high input heating power and large energy confinement time (to produce the highest temperature and density), while maintaining low impurity content. The principal limitation to the TFTR fusion power production was the disruptive stability limit. Secondary limitations were the confinement time, and limiter power handling capability.
32 citations
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TL;DR: The results suggest that IGF-I may contribute to the metachronous stimulation of apical NHE and PTC growth observed in many physiological and pathological conditions involving the human kidney.
Abstract: To determine whether insulin-like growth factor I (IGF-I) stimulated apical sodium/hydrogen exchange (NHE), confluent primary human proximal tubule cells (PTC) were incubated for 48 h in serum-free media in the presence or absence of 100 ng/ml IGF-I. Cells incubated in IGF-I demonstrated significant increases in thymidine incorporation (181.2 +/- 30.3% of control values; n = 12, P = 0.01) and in resting intracellular pH (pHi) (7.52 +/- 0.08 vs. 7.30 +/- 0.06; n = 20, P < 0.05), as determined by 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein quantitative microspectrofluorometry. Following intracellular acid loading, ethylisopropylamiloride (EIPA)-inhibitable H+ efflux and 22Na+ influx after 1 min were both significantly enhanced in IGF-I-treated cells compared with controls (8.78 +/- 1.69 vs. 3.03 +/- 0.72 mM/min and 3.47 +/- 0.49 vs. 1.55 +/- 0.35 nmol x mg protein(-1) x min(-1), respectively). 22Na+ uptake studies in PTC grown on permeable supports demonstrated preferential stimulation of apical vs. bas...
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TL;DR: In this paper, a multipulse Nd:YAG Thomson scattering system for measuring electron temperature and density profiles in the throat of the divertor of the Alcator C-Mod machine is presented.
Abstract: We have made and installed a multipulse Nd:YAG Thomson scattering system for measuring electron temperature and density profiles in the throat of the divertor of the Alcator C-Mod machine. The observing head is located in the vacuum vessel in a re-entrant chamber. It is optically fast and very compact. A system for providing feedback to maintain the laser beam alignment is a part of the observing head assembly. The head is designed to minimize eddy currents, and have a very rigid adjustable mounting to resist the forces generated by the eddy currents during plasma disruptions. A four wavelength polychromator using 25 element avalanche photodiode arrays for spatial resolution has been designed and built for this system. Two of these polychromators and a single observing head will provide 50 spatial resolution elements.
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TL;DR: Data imply that in patients with left ventricular ejection fraction of 0.25 or less, nitric oxide may not decrease systolic pulmonary artery pressure, and this effect would significantly limit the therapeutic role ofNitric oxide in Patients with severe heart failure.
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TL;DR: In this paper, the stored energy and neutron yield were determined from experimental data in the Tokamak Fusion Test Reactor (TFT Reactor) in different neutral-beam-heated operational domains, including Supershot, high poloidal beta, lowmode, and limiter highmode operational regimes.
Abstract: Scalings for the stored energy and neutron yield, determined from experimental data, are applied to both deuterium-only and deuterium–tritium plasmas in different neutral-beam-heated operational domains in the Tokamak Fusion Test Reactor [Nucl. Fusion 25, 1167 (1985)]. The domain of the data considered includes the Supershot, high poloidal beta, low-mode, and limiter high-mode operational regimes, as well as discharges with a reversed magnetic shear configuration. The new important parameter in the present scaling is the peakedness of the heating beam fueling profile shape. Ion energy confinement and neutron production are relatively insensitive to other plasma parameters compared to the beam fueling peakedness parameter and the heating beam power when considering plasmas that are stable to magnetohydrodynamic modes. However, the stored energy of the electrons is independent of the beam fueling peakedness. The implication of the scalings based on this parameter is related to theoretical transport models s...
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TL;DR: The facile formation of MoSe(2) was observed at low temperatures when the composition was above 50 atom % selenium, and a previously unreported compound was observed to form, Mo(3)Se, which has the A-15 crystal structure.
Abstract: The kinetics of compound formation in the molybdenum−selenium system has been investigated using elementally modulated reactants to control overall composition and diffusion length. We observed the facile formation of MoSe2 at low temperatures when the composition was above 50 atom % selenium. No evidence was found for the low-temperature formation of the other known stable molybdenum selenide, the cluster compound Mo6Se8. When the composition of the initially modulated reactant was close to 25% selenium, a previously unreported compound was observed to form. This new compound, Mo3Se, has the A-15 crystal structure. The superconducting transition temperature appears to be very sensitive to composition, with a sharp resistive transition at 7 K in one sample and a sharp diamagnetic transition observed in a second sample at 2.2 K. The kinetics of phase formation in this system is analyzed in terms of nucleation kinetics.
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TL;DR: It is confirmed that physiological increases in extracellular Na+ concentration directly stimulate human proximal tubule growth and Na+ transport and does not appear to be mediated by altered PTC secretion of, or responsiveness to, cytokines known to affect tubulegrowth and transport.
Abstract: In order to examine the nature and potential mechanisms of action of extracellular sodium on human proximal tubule growth and transport, quiescent primary cultures of human proximal tubule cells (PTC) were incubated for 24 h in serum-free, growth-factor-free culture media containing low (130 mmol/l), control (140 mmol/l) or high (150 mmol/l) Na+. Compared to control conditions, cells exposed to a high Na+ concentration demonstrated stimulated thymidine incorporation (121.8 ± 7.6%, P 0.1). Substitution of choline chloride for NaCl did not replicate these effects. Conversely, cells incubated in low-Na+ media showed reduced thymidine incorporation (77.2 ± 4.4%, P 0.1) and transforming growth factor-β1 (1.76 ± 0.32, 1.73 ± 0.33 and 1.45 ± 0.28 ng/mg protein, P > 0.1), and did not exhibit autocrine growth factor activity on separate PTC following adjustment of Na+ concentrations to 140 mmol/l by dialysis. Similarly, low-Na+, control or high-Na+ media did not modify the mitogenic responsiveness of PTC to insulin-like growth factor-I (IGF-I) or alter the affinity or number of PTC IGF-I binding sites. The results confirm that physiological increases in extracellular Na+ concentration directly stimulate human proximal tubule growth and Na+ transport. Such stimulation does not appear to be mediated by altered PTC secretion of, or responsiveness to, cytokines known to affect tubule growth and transport.
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TL;DR: The IBIS Collaborative Program in Enterprise Dynamics as mentioned in this paper is a research program bringing together the resources of the Melbourne Institute and IBIS Business Information Pty Ltd and funded by the Victorian Department of State Development and the ARC Collaborative Research Grants Program.
Abstract: *This paper is work in progress and is not to be cited without the authorsO imprimatur. The paper is the result of work being undertaken under the banner of the IBIS Collaborative Program in Enterprise Dynamics, a research program bringing together the resources of the Melbourne Institute and IBIS Business Information Pty Ltd and funded by the Victorian Department of State Development and the ARC Collaborative Research Grants Program. In addition to the Program participants, the authors are indebted to Vera Ha for her contribution to an earlier draft of this paper. The information in the paper was current at the time of submission.
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06 Oct 1997TL;DR: The ability to increase the quantity of lithium deposition into TFTR beyond that of the pellet injector while minimizing perturbations to the plasma provides interesting experimental and operational options as mentioned in this paper.
Abstract: The ability to increase the quantity of lithium deposition into TFTR beyond that of the pellet injector while minimizing perturbations to the plasma provides interesting experimental and operational options. Two additional lithium deposition tools were developed for possible application during the 1996 Experimental Schedule: a solid lithium target probe for real-time deposition, and a lithium effusion oven for deposition between discharges. The lithium effusion oven was operated in TFTR to deposit lithium on the inner limiter in the absence of plasma. This resulted in the third highest power TFTR discharge.
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TL;DR: In this paper, the structure and homogeneity of the superlattices in the ab plane were explored using off-specular X-ray diffraction (XRD), scanning electron microscopy, and scanning transmission x-ray microscopy (STXM).
Abstract: The structures of a series of (TiSe2)n(NbSe2)m superlattices grown through controlled crystallization of designed multilayer reactants have been studied. X-ray diffraction of the data of the superlattices after crystallization show considerable preferred orientation, with the basal plane of the dichalcogenide structure parallel to the substrate to within 0.1°. Lattice refinement using the observed (00l) diffraction maxima yields lattice parameters along the c axis that are consistent with those expected based on the target superlattices and lattice parameters of the binary constituents. These (00l) diffraction data, however, contain no information about the crystalline structure in the ab plane of the superlattice associated with the preferred c-axis orientation. Off-specular x-ray diffraction (XRD), scanning electron microscopy, and scanning transmission x-ray microscopy (STXM) were used to explore the structure and homogeneity of the superlattices in the ab plane. XRD results rule out preferred long-ran...
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TL;DR: In this article, a series of stable and metastable rare earth element−iron antimonides, controlling both composition and structure using multilayer reactants, were synthesized and analyzed.
Abstract: We have synthesized a series of stable and metastable rare earth element−iron antimonides, controlling both composition and structure using multilayer reactants. The stable rare earth iron element antimonides have the filled skutterudite structure (LaFe4P12) with a stoichiometry of 1 for the rare earth element. The metastable rare earth element−iron antimonides could be prepared with the entire sequence of rare earth elements. The lattice parameters of these metastable compounds were always larger than those of the corresponding more stable analog, and the occupancy of the rare earth element cation was found to be less than 1. Reitveld analysis of Lu1-xFe4Sb12 suggests that the late rare earth element compounds have a new distorted filled skutterudite structure. Structural trends are discussed in terms of their potential use as thermoelectric materials.
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TL;DR: The ability to form an amorphous reaction intermediate by the low temperature interdiffusion of a modulated elemental reactant is shown to be a function of the overall composition as well as elemental layer thicknesses in the niobium-selenium system as mentioned in this paper.
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01 Oct 1997TL;DR: The ability to increase the quantity of lithium deposition into TFTR beyond that of the Pellet Injector while minimizing perturbations to the plasma provides interesting experimental and operational options.
Abstract: The ability to increase the quantity of lithium deposition into TFTR beyond that of the Pellet Injector while minimizing perturbations to the plasma provides interesting experimental and operational options. Two additional lithium deposition tools were developed for possible application during the 1996 Experimental Schedule: a solid lithium target probe for real-time deposition, and a lithium effusion oven for deposition between discharges. The lithium effusion oven was operated in TFTR to deposit lithium on the Inner Limiter in the absence of plasma. This resulted in the third highest power TFTR discharge.
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06 Oct 1997TL;DR: In this article, a 1.6 Joule 1064 nm, 30 Hz pulsed YAG laser was used to form droplets from a heated cauldron containing liquid lithium.
Abstract: This paper describes the spallation of lithium into TFTR by laser and operated during the last run period. Liquid droplets of lithium were delivered into the edge of TFTR plasmas at low velocities in order to coat the interior of the TFTR vacuum vessel, and study the effects on machine performance. A 1.6 Joule 1064 nm, 30 Hz pulsed YAG laser was used to form droplets from a heated cauldron containing liquid lithium. The cauldron was resistance heated and part of a new probe head attached to the existing Bay D Long Probe. The cauldron was moved into the bottom of the vacuum vessel and positioned in the shadow of a poloidal limiter. The laser, associated equipment, and beam expanding optics were located in a walled enclosure approximately 46 m from the cauldron. Three fixed mirrors directed the beam through the test cell wall and into a box containing the focusing optics, steering mirror and a remote viewing CID video camera system. The focused beam was aimed vertically downward through a vacuum window and into the lithium cauldron. The system was controlled using LabView/sup TM/ software. Safety issues were resolved with engineered hardware design, interlocked circuits and administrative control. Lithium was successfully introduced into TFTR. Some interesting physics results were obtained. There was insufficient time to optimize the operation and design but initial results point to interesting possibilities for future experiments. Laboratory tests indicated that the cauldron could feasibly be positioned horizontally or vertically.