15,826 research outputs found

    Glass fiber processing for the Moon/Mars program: Center director's discretionary fund final report

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    Glass fiber has been produced from two lunar soil simulants. These two materials simulate lunar mare soil and lunar highland soil compositions, respectively. Short fibers containing recrystallized areas were produced from the as-received simulants. Doping the highland simulant with 8 weight percent B2-O3 yielded a material which could be spun continuously. The effects of lunar gravity on glass fiber formation were studied utilizing NASA's KC-135 aircraft. Gravity was found to play a major role in final fiber diameter

    Medial opening wedge high tibial osteotomy: A retrospective review of patient outcomes over 10 years

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    Objectives: High tibial osteotomy (HTO) has become a well-established treatment for unicompartmental osteoarthritis of the knee. Over the last 30 years, various techniques have been introduced to advance this procedure. The purpose of this study is to review the outcomes of patients who received medial opening wedge HTO over the last ten years (2002-2012) using a modern, low profile, medially based fixation device. In addition, we sought to determine if obese patients had a less favorable outcome than their non-obese counterparts. Methods: Ninety-three patients were identified from a surgical database as having undergone a HTO for medial compartment osteoarthritis of the knee with varus mal-alignment. All procedures were performed by one of two fellowship trained orthopedic surgeons from 2002-2012 utilizing a low profile fixation device and identical surgical technique. Minimum follow-up was one year for inclusion in the study. Outcomes were measured using Lysholm and WOMAC scores. Radiographs were evaluated to determine delayed union or non-union at the osteotomy site and surveillance was undertaken to evaluate post operative complications. Results: 93 patients were identified from the database, 63 (70%) were available for follow-up and are included in this analysis. Average follow-up time was 48 months (range 17 to 137). There were 44 males and 19 females. The average age was 45 years old. The average final Lysholm and WOMAC scores were 66.4 (range: 13-100) and 18.6 (range: 0-86) respectively. There was no significant difference in reported Lysholm or WOMAC scores between obese (BMI \u3e30) and non-obese patients (p=.31;p=.69). Complications were as follows: 3 patients required a surgical lysis of adhesions, 2 patients developed an infection, and 1 patient experienced a delayed union. At final follow-up, 18 patients received additional treatment on the affected knee: 11 required removal of symptomatic hardware, 5 received viscosupplementation, 2 underwent a total knee replacement. Conclusion: Low profile, medial based devices used in the setting of HTO is an accepted treatment for unicompartmental osteoarthritis of the knee. At final follow-up, a majority of patients reported positive outcomes and few complications. 18 patients required additional treatment for osteoarthritis. In our analysis, obese patients faired equally as well as their non-obese counterparts, with no significant difference in outcomes scores or complication rate. Survivorship of high tibial osteotomy was excellent in this series, with only 2 patients having undergone total knee replacement at last follow-up. © The Author(s) 2015

    The question of research relevance: a university management perspective

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    Purpose: The purpose of this paper is to empirically investigate the issue of research relevance from the frame of reference of university leaders. Its specific aim is to gain insights into how “relevance” is conceptualised, and the underlying assumptions upon which such conceptualizations are based. Design/methodology/approach: Adopting an inductive approach, the study collects and analyses data from semi-structured interviews with 31 senior research-related university leaders, and archival sources in five Australian universities. Findings: Research relevance is primarily viewed as a means of responding to government and political imperatives, as a pathway to ensuring university legitimacy, and as a means of generating further resources. The authors apply this understanding to develop a framework that adopts a nuanced view of relevance, reflecting what is driving research, and to whom research is principally targeted. Research limitations/implications: The evidence-base upon which the study is based represents a relatively small number of university leaders of Australian universities. Moreover, restricting the investigation to a few senior hierarchical levels nonetheless offers insights into high level organisational drivers hitherto neglected in the accounting research literature on university strategy, governance and accountability. While not addressing perceptions across the university population, this study focusses on and unpacks the social construction of relevance of this select group as research policy makers. Originality/value: As one of the few empirically informed investigations exploring the issue of research relevance from the perspective of university leaders, this study provides insights rather than “answers”. Its findings therefore serve as a foundational basis for further empirical and theoretical enquiry

    The Environment of ``E+A'' Galaxies

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    The violent star formation history of ``E+A'' galaxies and their detection almost exclusively in distant clusters is frequently used to link them to the ``Butcher-Oemler effect'' and to argue that cluster environment influences galaxy evolution. From 11113 spectra in the Las Campanas Redshift Survey, we have obtained a unique sample of 21 nearby ``E+A" galaxies. Surprisingly, a large fraction (about 75%) of these ``E+A''s lie in the field. Therefore, interactions with the cluster environment, in the form of the ICM or cluster potential, are not essential for ``E+A'' formation. If one mechanism is responsible for ``E+A''s, their existence in the field and the tidal features in at least 5 of the 21 argue that galaxy-galaxy interactions and mergers are that mechanism. The most likely environments for such interactions are poor groups, which have lower velocity dispersions than clusters and higher galaxy densities than the field. In hierarchical models, groups fall into clusters in greater numbers at intermediate redshifts than they do today. Thus, the Butcher-Oemler effect may reflect the typical evolution of galaxies in groups and in the field rather than the influence of clusters on star formation in galaxies. This abstract is abridged.Comment: 39 uuencoded, compressed pages (except Fig 1), complete preprint at ftp://ociw.edu/pub/aiz/eplusa.ps, ApJ, submitte

    Influence of qubit displacements on quantum logic operations in a silicon-based quantum computer with constant interaction

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    The errors caused by qubit displacements from their prescribed locations in an ensemble of spin chains are estimated analytically and calculated numerically for a quantum computer based on phosphorus donors in silicon. We show that it is possible to polarize (initialize) the nuclear spins even with displaced qubits by using Controlled NOT gates between the electron and nuclear spins of the same phosphorus atom. However, a Controlled NOT gate between the displaced electron spins is implemented with large error because of the exponential dependence of exchange interaction constant on the distance between the qubits. If quantum computation is implemented on an ensemble of many spin chains, the errors can be small if the number of chains with displaced qubits is small

    The supercluster--void network III. The correlation function as a geometrical statistic

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    We investigate properties of the correlation function of clusters of galaxies using geometrical models. On small scales the correlation function depends on the shape and the size of superclusters. On large scales it describes the geometry of the distribution of superclusters. If superclusters are distributed randomly then the correlation function on large scales is featureless. If superclusters and voids have a tendency to form a regular lattice then the correlation function on large scales has quasi-regularly spaced maxima and minima of decaying amplitude; i.e., it is oscillating. The period of oscillations is equal to the step size of the grid of the lattice. We calculate the power spectrum for our models and compare the geometrical information of the correlation function with other statistics. We find that geometric properties (the regularity of the distribution of clusters on large scales) are better quantified by the correlation function. We also analyse errors in the correlation function and the power spectrum by generating random realizations of models and finding the scatter of these realizations.Comment: MNRAS LaTex style, 12 pages, 7 PostScript figures embedded, accepted by MNRA

    Spectral signatures of photosynthesis I: Review of Earth organisms

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    Why do plants reflect in the green and have a 'red edge' in the red, and should extrasolar photosynthesis be the same? We provide: 1) a brief review of how photosynthesis works; 2) an overview of the diversity of photosynthetic organisms, their light harvesting systems, and environmental ranges; 3) a synthesis of photosynthetic surface spectral signatures; 4) evolutionary rationales for photosynthetic surface reflectance spectra with regard to utilization of photon energy and the planetary light environment. Given the surface incident photon flux density spectrum and resonance transfer in light harvesting, we propose some rules with regard to where photosynthetic pigments will peak in absorbance: a) the wavelength of peak incident photon flux; b) the longest available wavelength for core antenna or reaction center pigments; and c) the shortest wavelengths within an atmospheric window for accessory pigments. That plants absorb less green light may not be an inefficient legacy of evolutionary history, but may actually satisfy the above criteria.Comment: 69 pages, 7 figures, forthcoming in Astrobiology March 200

    The Luminosity Function of Galaxies in the Las Campanas Redshift Survey

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    We present the RR-band luminosity function for a sample of 18678 galaxies, with average redshift z=0.1z = 0.1, from the Las Campanas Redshift Survey. The luminosity function may be fit by a Schechter function with M∗=−20.29±0.02+5log⁥hM^* = -20.29 \pm 0.02 + 5 \log h, α=−0.70±0.05\alpha = -0.70 \pm 0.05, and $\phi^* = 0.019 \pm 0.001 \ h^3 Mpc~Mpc^{-3},forabsolutemagnitudes, for absolute magnitudes -23.0 \leq M - 5 \log h \leq -17.5.Wecompareourluminosityfunctiontothatfromotherredshiftsurveys;inparticularournormalizationisconsistentwiththatoftheStromlo−APMsurvey,andisthereforeafactoroftwobelowthatimpliedbythe. We compare our luminosity function to that from other redshift surveys; in particular our normalization is consistent with that of the Stromlo-APM survey, and is therefore a factor of two below that implied by the b_J \approx 20brightgalaxycounts.Ournormalizationthusindicatesthatmuchmoreevolutionisneededtomatchthefaintgalaxycountdata,comparedtominimalevolutionmodelswhichnormalizeat bright galaxy counts. Our normalization thus indicates that much more evolution is needed to match the faint galaxy count data, compared to minimal evolution models which normalize at b_J \approx 20.Also,weshowthatourfaint−endslope. Also, we show that our faint-end slope \alpha = -0.7,though‘‘shallowerâ€Čâ€Čthantypicalpreviousvalues, though ``shallower'' than typical previous values \alpha = -1,resultsprimarilyfromfittingthedetailedshapeoftheLCRSluminosityfunction,ratherthanfromanyabsenceofintrinsicallyfaintgalaxiesfromoursurvey.Finally,using[OII]3727equivalentwidth, results primarily from fitting the detailed shape of the LCRS luminosity function, rather than from any absence of intrinsically faint galaxies from our survey. Finally, using [OII] 3727 equivalent width W_{\lambda} = 5 A˚ asthedividingline,wefindsignificantdifferencesintheluminosityfunctionsofemissionandnon−emissiongalaxies,particularlyintheir~\AA \ as the dividing line, we find significant differences in the luminosity functions of emission and non-emission galaxies, particularly in their \alphavalues.EmissiongalaxieshaveSchechterparameters values. Emission galaxies have Schechter parameters M^* = -20.03 \pm 0.03 + 5 \log hand and \alpha = -0.9 \pm 0.1,whilenon−emissiongalaxiesaredescribedby, while non-emission galaxies are described by M^* = -20.22 \pm 0.02 + 5 \log hand and \alpha = -0.3 \pm 0.1$. (abridged abstract)Comment: 41 pages, including 13 postscript figures, uses AASTEX v4.0 style files. Important clarification of R-band definition, plus correction of luminosity densities and updated references. Main conclusions unchanged. Final version to appear in Ap

    Discriminating cool-water from warm-water carbonates and their diagenetic environments using element geochemistry: the Oligocene Tikorangi Formation (Taranaki Basin) and the dolomite effect

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    Fields portrayed within bivariate element plots have been used to distinguish between carbonates formed in warm- (tropical) water and cool- (temperate) water depositional settings. Here, element concentrations (Ca, Mg, Sr, Na, Fe, and Mn) have been determined for the carbonate fraction of bulk samples from the late Oligocene Tikorangi Formation, a subsurface, mixed dolomite-calcite, cool-water limestone sequence in Taranaki Basin, New Zealand. While the occurrence of dolomite is rare in New Zealand Cenozoic carbonates, and in cool-water carbonates more generally, the dolomite in the Tikorangi carbonates is shown to have a dramatic effect on the "traditional" positioning of cool-water limestone fields within bivariate element plots. Rare undolomitised, wholly calcitic carbonate samples in the Tikorangi Formation have the following average composition: Mg 2800 ppm; Ca 319 100 ppm; Na 800 ppm; Fe 6300 ppm; Sr 2400 ppm; and Mn 300 ppm. Tikorangi Formation dolomite-rich samples (>15% dolomite) have average values of: Mg 53 400 ppm; Ca 290 400 ppm; Na 4700 ppm; Fe 28 100 ppm; Sr 5400 ppm; and Mn 500 ppm. Element-element plots for dolomite-bearing samples show elevated Mg, Na, and Sr values compared with most other low-Mg calcite New Zealand Cenozoic limestones. The increased trace element contents are directly attributable to the trace element-enriched nature of the burial-derived dolomites, termed here the "dolomite effect". Fe levels in the Tikorangi Formation carbonates far exceed both modern and ancient cool-water and warm-water analogues, while Sr values are also higher than those in modern Tasmanian cool-water carbonates, and approach modern Bahaman warm-water carbonate values. Trace element data used in conjunction with more traditional petrographic data have aided in the diagenetic interpretation of the carbonate-dominated Tikorangi sequence. The geochemical results have been particularly useful for providing more definitive evidence for deep burial dolomitisation of the deposits under the influence of marine-modified pore fluids
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