30,278 research outputs found

    Energy Efficient Engine Program: Technology Benefit/Cost Study, Volume II

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    The Benefit/Cost Study portion of the NASA-sponsored Energy Efficient Engine Component Development and Integration program was successful in achieving its objectives: identification of air transport propulsion system technology requirements for the years 2000 and 2010, and formulation of programs for developing these technologies. It is projected that the advanced technologies identified, when developed to a state of readiness, will provide future commercial and military turbofan engines with significant savings in fuel consumption and related operating costs. These benefits are significant and far from exhausted. The potential savings translate into billions of dollars in annual savings for the airlines. Analyses indicate that a significant portion of the overall savings is attributed to aerodynamic and structure advancements. Another important consideration in acquiring these benefits is developing a viable reference technology base that will permit engines to operate at substantially higher overall pressure ratios and bypass ratios. Results have pointed the direction for future research and a comprehensive program plan for achieving this was formulated. The next major step is initiating the program effort that will convert the advanced technologies into the expected benefits

    Kinetics of the reduction of metalloproteins by chromous ion

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    The reduction of Cu(330) in Rhus vernicifera laccase by chromous ion is 30% faster than reduction of Cu(614) at room temperature [pH 4.8, µ = 0.1 (NaCl)], and two parallel first-order paths, attributed to heterogeneity of the protein, are observed at both wavelengths. The reactions of stellacyanin, spinach and French-bean plastocyanins, and cytochrome c with chromous ion under similar conditions are faster than that with laccase by factors of 102 to 104, and are first order in protein concentration. Comparison of rates and activation parameters for the reduction of "blue" copper in laccase, stellacyanin, and the two plastocyanins indicates that reduction of the Cu(614) site in laccase may occur by intramolecular electron transfer from one of the Cu(330) sites. Our value of ΔH (17.4 kcal/mol) for the chromous ion reduction of cytochrome c is consistent with a mechanism in which major conformational changes in the protein must accompany electron transfer

    Rotation and Macroturbulence in Metal-poor Field Red Giant and Red Horizontal Branch Stars

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    We report the results for rotational velocities, Vrot sin i, and macroturbulence dispersion, zeta(RT), for 12 metal-poor field red giant branch stars and 7 metal-poor field red horizontal branch stars. The results are based on Fourier transform analyses of absorption line profiles from high-resolution (R ~ 120,000), high-S/N (~ 215 per pixel) spectra obtained with the Gecko spectrograph at CFHT. We find that the zeta(RT) values for the metal-poor RGB stars are very similar to those for metal-rich disk giants studied earlier by Gray and his collaborators. Six of the RGB stars have small rotational values, less than 2.0 km/sec, while five show significant rotation, over 3 km/sec. The fraction of rapidly rotating RHB stars is somewhat lower than found among BHB stars. We devise two empirical methods to translate the line-broadening results obtained by Carney et al. (2003, 2008) into Vrot sin i for all the RGB and RHB stars they studied. Binning the RGB stars by luminosity, we find that most metal-poor field RGB stars show no detectable sign, on average, of rotation. However, the most luminous stars, with M(V) <= -1.5, do show net rotation, with mean values of 2 to 4 km/sec, depending on the algorithm employed, and these stars also show signs of radial velocity jitter and mass loss.Comment: accepted for publication in the Astronomical Journa

    Strain-mediated metal-insulator transition in epitaxial ultra-thin films of NdNiO3

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    We have synthesized epitaxial NdNiO3_{3} ultra-thin films in a layer-by-layer growth mode under tensile and compressive strain on SrTiO3_{3} (001) and LaAlO3_3 (001), respectively. A combination of X-ray diffraction, temperature dependent resistivity, and soft X-ray absorption spectroscopy has been applied to elucidate electronic and structural properties of the samples. In contrast to the bulk NdNiO3_{3}, the metal-insulator transition under compressive strain is found to be completely quenched, while the transition remains under the tensile strain albeit modified from the bulk behavior.Comment: 4 pages, 4 figure

    Is Growing Livestock Inventories a Sustainable Initiative Given Phosphorus Crop Removal Regulations?

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    As environmental regulations continue to tighten and shift from nitrogen to phosphorus-based application standards for manure, phosphorus removal will become increasingly important for any state considering a livestock growth initiative. A framework was developed that can determine a state’s phosphorus removal capacity based upon production of livestock and crops and varying phosphorus removal standards. The state level results indicate that Indiana, along with Arizona, Illinois, Iowa, Kansas, and Texas, are well positioned to undertake a livestock growth initiative given that each state has excess phosphorous removal capacity.Agribusiness, Livestock Production/Industries,

    Orbital control in strained ultra-thin LaNiO3_3/LaAlO3_3 superlattices

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    In pursuit of rational control of orbital polarization, we present a combined experimental and theoretical study of single unit cell superlattices of the correlated metal LaNiO3_3 and the band insulator LaAlO3_3. Polarized x-ray absorption spectra show a distinct asymmetry in the orbital response under strain. A splitting of orbital energies consistent with octahedral distortions is found for the case of compressive strain. In sharp contrast, for tensile strain, no splitting is found although a strong orbital polarization is present. Density functional theory calculations including a Hubbard U term reveal that this asymmetry is a result of the interplay of strain and confinement induces octahedral rotations and distortions and altered covalency in the bonding across the interfacial Ni-O-Al apical oxygen, leading to a charge disporportionation at the Ni sites for tensile strain.Comment: 4 pages. 5 figure

    Effect of polar discontinuity on the growth of LaNiO3/LaAlO3 superlattices

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    We have conducted a detailed microscopic investigation of [LaNiO3(1 u.c.)/LaAlO3(1 u.c.)]N superlattices grown on (001) SrTiO3 and LaAlO3 to explore the influence of polar mismatch on the resulting electronic and structural properties. Our data demonstrate that the initial growth on the non-polar SrTiO3 surface leads to a rough morphology and unusual 2+ valence of Ni in the first LaNiO3 layer, which is not observed after growth on the polar surface of LaAlO3. A newly devised model suggests that the polar mismatch can be resolved if the perovskite layers grow with an excess of LaO, which also accounts for the observed electronic, chemical, and structural effects.Comment: 3 pages, 3 figure

    Rehabilitation after anterior cruciate ligament reconstruction: A systematic review

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    BACKGROUND: Rigorous rehabilitation after anterior cruciate ligament (ACL) reconstruction is necessary for a successful surgical outcome. A large number of clinical trials continue to assess aspects of this rehabilitation process. Prior systematic reviews evaluated fifty-four Level-I and II clinical trials published through 2005. METHODS: Eighty-five articles from 2006 to 2010 were identified utilizing multiple search engines. Twenty-nine Level-I or II studies met inclusion criteria and were evaluated with use of the CONSORT (Consolidated Standards of Reporting Trials) criteria. Topics included in this review are postoperative bracing, accelerated strengthening, home-based rehabilitation, proprioception and neuromuscular training, and six miscellaneous topics investigated in single trials. RESULTS: Bracing following ACL reconstruction remains neither necessary nor beneficial and adds to the cost of the procedure. Early return to sports needs further research. Home-based rehabilitation can be successful. Although neuromuscular interventions are not likely to be harmful to patients, they are also not likely to yield large improvements in outcomes or help patients return to sports faster. Thus, they should not be performed to the exclusion of strengthening and range-of-motion exercises. Vibration training may lead to faster and more complete proprioceptive recovery but further evidence is needed. CONCLUSIONS: Several new modalities for rehabilitation after ACL reconstruction may be helpful but should not be performed to the exclusion of range-of-motion, strengthening, and functional exercises. Accelerated rehabilitation does not appear to be harmful but further investigation of rehabilitation timing is warranted. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence
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