11,842 research outputs found

    Main propulsion system test requirements for the two-engine Shuttle-C

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    The Shuttle-C is an unmanned cargo carrying derivative of the space shuttle with optional two or three space shuttle main engines (SSME's), whereas the shuttle has three SSME's. Design and operational differences between the Shuttle-C and shuttle were assessed to determine requirements for additional main propulsion system (MPS) verification testing. Also, reviews were made of the shuttle main propulsion test program objectives and test results and shuttle flight experience. It was concluded that, if significant MPS modifications are not made beyond those currently planned, then main propulsion system verification can be concluded with an on-pad flight readiness firing

    A model for projectile fragmentation

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    A model for projectile fragmentation is developed whose origin can be traced back to the Bevalac era. The model positions itself between the phenomenological EPAX parametrization and transport models like "Heavy Ion Phase Space Exploration" (HIPSE) model and antisymmetrised molecular dynamics (AMD) model. A very simple impact parameter dependence of input temperature is incorporated in the model which helps to analyze the more peripheral collisions. The model is applied to calculate the charge, isotopic distributions, average number of intermediate mass fragments and the average size of largest cluster at different Z_{bound} of different projectile fragmentation reactions at different energies.Comment: Talk given by Gargi Chaudhuri at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. 10 pages, 7 figure

    Distinguishability of hyperentangled Bell state by linear evolution and local projective measurement

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    Measuring an entangled state of two particles is crucial to many quantum communication protocols. Yet Bell state distinguishability using a finite apparatus obeying linear evolution and local measurement is theoretically limited. We extend known bounds for Bell-state distinguishability in one and two variables to the general case of entanglement in nn two-state variables. We show that at most 2n+1−12^{n+1}-1 classes out of 4n4^n hyper-Bell states can be distinguished with one copy of the input state. With two copies, complete distinguishability is possible. We present optimal schemes in each case.Comment: 5 pages, 2 figure

    Work group inclusion : test of a scale and model

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    We develop a theoretically based 10-item measure of work group inclusion comprised of two components (belongingness and uniqueness) and use this measure to empirically test the nomological network of work group inclusion developed by Shore et al. In Phase 1, we use two samples of full-time employees to develop and refine items as well as establish content validity. In Phase 2, we demonstrate convergent, discriminant, and incremental validity with both conceptually related and unrelated constructs. In Phase 3, we use data from an additional sample of employees and supervisors to test criterion-related validity and mediation by examining the multilevel relationships between inclusion and important antecedents and outcomes. Across the three phases of our study, the results demonstrate support not only for the factor structure, reliability, and validity of our work group inclusion measure but also for a theoretical model in which the construct of inclusion has important implications for individuals and organizations

    Antiferromagnetic Order of the Ru and Gd in Superconducting RuSr2GdCu2O8

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    Neutron diffraction has been used to study the magnetic order in RuSr{2}GdCu2O8. The Ru moments order antiferromagnetically at T{N}=136(2)K, coincident with the previously reported onset of ferromagnetism. Neighboring spins are antiparallel in all three directions, with a low T moment of 1.18(6) mu {B} along the c-axis. Our measurements put an upper limit of ~0.1 mu{B} to any net zero-field moment, with fields exceeding ~0.4T needed to induce a measurable magnetization. The Gd ions order independently at T{N}=2.50(2)K with the same spin configuration. PACS numbers: 74.72.Jt, 75.25.+z, 74.25.Ha, 75.30.KzComment: Four pages, Latex, 5 eps figure

    Nitrogen Concentration in Cell Wall of Warm-Season Perennial Grasses

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    The objectives of this experiment were to evaluate the influence of N fertilizer, age of regrowth, and season on concentration of N in cell-wall fractions of three warm-season perennial grasses (limpograss, [Hemarthria altissima (Poir.) Stapf et C.E. Hubb.], bermudagrass [Cynodon spp.], and bahiagrass [Paspalum notatum Flügge]. The herbage neutral detergent insoluble nitrogen (NDIN) fraction composed almost half of total N in these grasses. Though acid detergent insoluble nitrogen (ADIN) concentrations generally were 80 g kg-1 of total N or less, this fraction is indigestible and unavailable and composes a significant portion of a nutrient that may already be in short supply in warm-season grasses

    Inclusive leadership : realizing positive outcomes through belongingness and being valued for uniqueness

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    We introduce a theoretically-grounded conceptualization of inclusive leadership and present a framework for understanding factors that contribute to and follow from inclusive leadership within work groups. We conceptualize inclusive leadership as a set of positive leader behaviors that facilitate group members perceiving belongingness in the work group while maintaining their uniqueness within the group as they fully contribute to group processes and outcomes. We propose that leader pro-diversity beliefs, humility, and cognitive complexity increase the propensity of inclusive leader behaviors. We identify five categories of inclusive leadership behaviors that facilitate group members' perceptions of inclusion, which in turn lead to member work group identification, psychological empowerment, and behavioral outcomes (creativity, job performance, and reduced turnover) in the pursuit of group goals. This framework provides theoretical grounding for the construct of inclusive leadership while advancing our understanding of how leaders can increase diverse work group effectiveness

    Spin Dynamics of the Magnetoresistive Pyrochlore Tl_2Mn_2O_7

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    Neutron scattering has been used to study the magnetic order and spin dynamics of the colossal magnetoresistive pyrochlore Tl_2Mn_2O_7. On cooling from the paramagnetic state, magnetic correlations develop and appear to diverge at T_C (123 K). In the ferromagnetic phase well defined spin waves are observed, with a gapless (Δ<0.04\Delta <0.04 meV) dispersion relation E=Dq^{2} as expected for an ideal isotropic ferromagnet. As T approaches T_C from low T, the spin waves renormalize, but no significant central diffusive component to the fluctuation spectrum is observed in stark contrast to the La1−x_{1-x}(Ca,Ba,Sr)x_xMnO3_3 system. These results argue strongly that the mechanism responsible for the magnetoresistive effect has a different origin in these two classes of materials.Comment: 4 pages (RevTex), 4 figures (encapsulated postscript), to be published in Phys. Rev. Let

    Reconstructing the Regulatory Kinase Pathways of Myogenesis from Phosphopeptide Data

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    Multiple kinase activities are required for skeletal muscle differentiation. However, the mechanisms by which these kinase pathways converge to coordinate the myogenic process are unknown. Using multiple phosphoprotein and phosphopeptide enrichment techniques we obtained phosphopeptides from growing and differentiating C2C12 muscle cells and determined specific peptide sequences using LC-MS/MS. To place these phosphopeptides into a rational context, a bioinformatics approach was used. Phosphorylation sites were matched to known site-specific and to site non-specific kinase-substrate interactions, and then other substrates and upstream regulators of the implicated kinases were incorporated into a model network of protein-protein interactions. The model network implicated several kinases of known relevance to myogenesis including AKT, GSK3, CDK5, p38, DYRK, and MAPKAPK2 kinases. This combination of proteomics and bioinformatics technologies should offer great utility as the volume of protein-protein and kinase-substrate information continues to increase

    Temperature and field dependence of the phase separation, structure, and magnetic ordering in La1−x_{1-x}Cax_xMnO3_3, (x=0.47x=0.47, 0.50, and 0.53)

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    Neutron powder diffraction measurements, combined with magnetization and resistivity data, have been carried out in the doped perovskite La1−x_{1-x}Cax_xMnO3_3 (x=0.47x=0.47, 0.50, and 0.53) to elucidate the structural, magnetic, and electronic properties of the system around the composition corresponding to an equal number of Mn3+ and Mn4+. At room temperature all three samples are paramagnetic and single phase, with crystallographic symmetry Pnma. The samples then all become ferromagnetic (FM) at TC≈265T_C\approx 265 K. At ∼230\sim 230 K, however, a second distinct crystallographic phase (denoted A-II) begins to form. Initially the intrinsic widths of the peaks are quite large, but they narrow as the temperature decreases and the phase fraction increases, indicating microscopic coexistence. The fraction of the sample that exhibits the A-II phase increases with decreasing temperature and also increases with increasing Ca doping, but the transition never goes to completion to the lowest temperatures measured (5 K) and the two phases therefore coexist in this temperature-composition regime. Phase A-II orders antiferromagnetically (AFM) below a N\'{e}el temperature TN≈160T_N \approx 160 K, with the CE-type magnetic structure. Resistivity measurements show that this phase is a conductor, while the CE phase is insulating. Application of magnetic fields up to 9 T progressively inhibits the formation of the A-II phase, but this suppression is path dependent, being much stronger for example if the sample is field-cooled compared to zero-field cooling and then applying the field. The H-T phase diagram obtained from the diffraction measurements is in good agreement with the results of magnetization and resistivity.Comment: 12 pages, 3 tables, 11 figure
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