981 research outputs found

    Performance, emissions, and physical characteristics of a rotating combustion aircraft engine

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    The RC2-75, a liquid cooled two chamber rotary combustion engine (Wankel type), designed for aircraft use, was tested and representative baseline (212 KW, 285 BHP) performance and emissions characteristics established. The testing included running fuel/air mixture control curves and varied ignition timing to permit selection of desirable and practical settings for running wide open throttle curves, propeller load curves, variable manifold pressure curves covering cruise conditions, and EPA cycle operating points. Performance and emissions data were recorded for all of the points run. In addition to the test data, information required to characterize the engine and evaluate its performance in aircraft use is provided over a range from one half to twice its present power. The exhaust emissions results are compared to the 1980 EPA requirements. Standard day take-off brake specific fuel consumption is 356 g/KW-HR (.585 lb/BHP-HR) for the configuration tested

    Spin density wave anomaly at 140 K in the ternary iron arsenide BaFe2As2

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    The ternary iron arsenide BaFe2As2 with the tetragonal ThCr2Si2-type structure exhibits a spin density wave (SDW) anomaly at 140 K, very similar to LaFeAsO, the parent compound of the iron arsenide superconductors. BaFe2As2 is a poor Pauli-paramagnetic metal and undergoes a structural and magnetic phase transition at 140 K, accompanied by strong anomalies in the specific heat, electrical resistance and magnetic susceptibility. In the course of this transition, the space group symmetry changes from tetragonal (I4/mmm) to orthorhombic (Fmmm). 57Fe Moessbauer spectroscopy experiments show a single signal at room temperature and full hyperfine field splitting below the phase transition temperature (5.2 T at 77 K). Our results suggest that BaFe2As2 can serve as a new parent compound for oxygen-free iron arsenide superconductors.Comment: 4 pages, 6 figures, submitted to PR

    Beyond platitudes: a qualitative study of Australian Aboriginal people's perspectives on biobanking.

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    BACKGROUND: Biobanks are vital resources for genetics and genomics, and it is broadly recognised that for maximal benefit it is essential that they include samples and data from diverse ancestral groups. The inclusion of First Nations people, in particular, is important to prevent biobanking research from exacerbating existing health inequities, and to ensure that these communities share in the benefits arising from research. AIMS: To explore the perspectives of Australian Aboriginal people whose tissue - or that of their family members - has been stored in the biobank of the National Centre for Indigenous Genomics (NCIG). METHODS: Semi-structured interviews with 42 Aboriginal people from the Titjikala, Galiwinku, Tiwi Islands, Yarrabah, Fitzroy Crossing, Derby, One Arm Point and Mulan communities, as well as a formal discussion with A. Hermes, an Indigenous Community Engagement Coordinator at the NCIG who had conducted the interviews. The interviews and the structured discussion were double coded using a procedure informed by Charmaz's outline of grounded theory analysis and Morse's outline of the cognitive basis of qualitative research. RESULTS: In this article, we report on A. Hermes' interviews with members from the above Aboriginal communities, as well as on her personal views, experiences, and interpretations of the interviews she conducted with other community members. We found that participation in the NCIG biobank raised issues around broken trust, grief and loss, but also - somewhat unexpectedly - was perceived as a source of empowerment, hope and reconnection. CONCLUSIONS: This research reminds us (again) of the need to engage deeply with communities in order to respond appropriately with respect for their cultural values and norms, and to develop culturally relevant policies and processes that enhance the benefits of biobank participation and minimise potential harms

    High-speed Photometric Observations of ZZ Ceti White Dwarf Candidates

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    We present high-speed photometric observations of ZZ Ceti white dwarf candidates drawn from the spectroscopic survey of bright DA stars from the Villanova White Dwarf Catalog by Gianninas et al., and from the recent spectroscopic survey of white dwarfs within 40 parsecs of the Sun by Limoges et al. We report the discovery of six new ZZ Ceti pulsators from these surveys, and several photometrically constant DA white dwarfs, which we then use to refine the location of the ZZ Ceti instability strip.Comment: 4 pages, 1 table, 2 figures, to appear in "19th European White Dwarf Workshop" in the ASP Conference Serie

    Search for the Θˉ\bar{\Theta}^- \to K^- nˉ\bar{n} with PHENIX

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    The PHENIX experiment at RHIC should be sensitive to decays of the the anti--pentaquark Θˉ\bar{\Theta}^- via the K^- nˉ\bar{n} channel. Charged kaons can be identified using the standard tracking and time of flight up to a momentum of 1.5 GeV/c. Anti--neutron candidates are detected via their annihilation signal in the highly segmented electromagnetic calorimeter (EMCal). In order to assess the quality of the anti--neutron identification we reconstruct the Σˉnˉπ\bar{\Sigma} \to \bar{n}\pi. As an additional crosscheck the invariant mass of K+^+ nˉ\bar{n} is reconstructed where no resonance in the pentaquark mass range is expected. At the present time no enhancement at the expected pentaquark mass is observed in dAu collisions at $\sqrt{s_{NN}} = 200 GeV.Comment: 4 pages 5 figures contribution to the proceedings of the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (Quark Matter, Oakland, January 11-17, 2004). To appear in the proceedings (Journal of Physics G

    The Physics of the Colloidal Glass Transition

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    As one increases the concentration of a colloidal suspension, the system exhibits a dramatic increase in viscosity. Structurally, the system resembles a liquid, yet motions within the suspension are slow enough that it can be considered essentially frozen. This kinetic arrest is the colloidal glass transition. For several decades, colloids have served as a valuable model system for understanding the glass transition in molecular systems. The spatial and temporal scales involved allow these systems to be studied by a wide variety of experimental techniques. The focus of this review is the current state of understanding of the colloidal glass transition. A brief introduction is given to important experimental techniques used to study the glass transition in colloids. We describe features of colloidal systems near and in glassy states, including tremendous increases in viscosity and relaxation times, dynamical heterogeneity, and ageing, among others. We also compare and contrast the glass transition in colloids to that in molecular liquids. Other glassy systems are briefly discussed, as well as recently developed synthesis techniques that will keep these systems rich with interesting physics for years to come.Comment: 56 pages, 18 figures, Revie

    Transverse Momentum Dependent Parton Distribution/Fragmentation Functions at an Electron-Ion Collider

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    We present a summary of a recent workshop held at Duke University on Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark-Gluon Interactions. The transverse momentum dependent parton distribution functions (TMDs), parton-to-hadron fragmentation functions, and multi-parton correlation functions, were discussed extensively at the Duke workshop. In this paper, we summarize first the theoretical issues concerning the study of partonic structure of hadrons at a future electron-ion collider (EIC) with emphasis on the TMDs. We then present simulation results on experimental studies of TMDs through measurements of single spin asymmetries (SSA) from semi-inclusive deep-inelastic scattering (SIDIS) processes with an EIC, and discuss the requirement of the detector for SIDIS measurements. The dynamics of parton correlations in the nucleon is further explored via a study of SSA in D (`D) production at large transverse momenta with the aim of accessing the unexplored tri-gluon correlation functions. The workshop participants identified the SSA measurements in SIDIS as a golden program to study TMDs in both the sea and valence quark regions and to study the role of gluons, with the Sivers asymmetry measurements as examples. Such measurements will lead to major advancement in our understanding of TMDs in the valence quark region, and more importantly also allow for the investigation of TMDs in the sea quark region along with a study of their evolution.Comment: 44 pages 23 figures, summary of Duke EIC workshop on TMDs accepted by EPJ
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