3,162 research outputs found

    Effects of mechanically separated dairy cow slurry on grazing performance

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    From Castalia to Wikipedia: openness and closure in knowledge communities

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    Supporting International Ab Initio Flight Students Through English Language Training

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    Effective communication between ab initio flight students and their instructors is critical for efficient flight training; additionally, clear radio communications between student pilots and air traffic controllers is imperative for smooth and incident-free airport operations. During the Fall 2019 semester, Embry-Riddle Aeronautical University (ERAU) at Daytona Beach implemented a new semi-intensive eight-week course to improve the communicative skills of its international students who speak English as a second language. This presentation describes the cross-campus and cross-departmental collaboration that took place to implement this new course. The stages that will be described include (a) the pre-screening of the students using ERAU’s online, remotely administered English for Flight Training Assessment (EFTA)™, a project initiated by Daytona Beach’s Applied Aviation Sciences Department and the Embry-Riddle Language Institute, and (b) the employment of a curriculum specifically designed for ab-initio flight students based on flight training materials created by the Aviation English Specialists at ERAU, Worldwide. The presenters will describe the teaching approaches used during the course and provide insights about the challenges faced and lessons learned throughout the eight weeks. The topic of aviation-familiarity for English language instructors will be discussed along with plans for improving the course. The audience will leave with insights about how to directly support international ab initio flight students and understand how ERAU’s approach to effective English language training can serve as an exemplar for the industry

    Leptonic and Semileptonic Decays of Pseudoscalar Mesons

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    We employ the relativistic constituent quark model to give a unified description of the leptonic and semileptonic decays of pseudoscalar mesons (\pi, K, D, D_s, B, B_s). The calculated leptonic decay constants and form factors are found to be in good agreement with available experimental data and other approaches. We reproduce the results of spin-flavor symmetry in the heavy quark limit.Comment: 12 pages LaTeX (elsart.sty) + 4 figures; added references, to appear in Phys. Lett.

    ρ\rho Polarization and `Model Independent' Extraction of Vub/Vcd|V_{ub}|/|V_{cd}| from DρνD\to\rho\ell\nu and BρνB\to\rho\ell\nu

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    We briefly discuss the predictions of the heavy quark effective theory for the semileptonic decays of a heavy pseudoscalar to a light one, or to a light vector meson. We point out that measurement of combinations of differential helicity decay rates at Cleo-c and the BB factories can provide a model independent means of extracting the ratio Vub/Vcd|V_{ub}|/|V_{cd}|. We briefly discuss the corrections to this prediction.Comment: 8 pages, LaTeX, 1 figur

    Valence-quark distributions in the pion

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    We calculate the pion's valence-quark momentum-fraction probability distribution using a Dyson-Schwinger equation model. Valence-quarks with an active mass of 0.30 GeV carry 71% of the pion's momentum at a resolving scale q_0=0.54 GeV = 1/(0.37 fm). The shape of the calculated distribution is characteristic of a strongly bound system and, evolved from q_0 to q=2 GeV, it yields first, second and third moments in agreement with lattice and phenomenological estimates, and valence-quarks carrying 49% of the pion's momentum. However, pointwise there is a discrepancy between our calculated distribution and that hitherto inferred from parametrisations of extant pion-nucleon Drell-Yan data.Comment: 8 pages, 3 figures, REVTEX, aps.sty, epsfig.sty, minor corrections, version to appear in PR

    The semileptonic decays of the B_c meson

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    We study the semileptonic transitions B_c to \eta_c, J/\psi, D, D^*, B, B^*, B_s, B_s^* in the framework of a relativistic constituent quark model. We use experimental data on leptonic J/\psi decay, lattice and QCD sum rule results on leptonic B_c decay, and on radiative \eta_c transitions to adjust the quark model parameters. We compute all form factors of the above semileptonic B_c-transitions and give predictions for various semileptonic B_c decay modes including their \tau-modes when they are kinematically accessible. The implications of heavy quark symmetry for the semileptonic decays are discussed and are shown to be manifest in our explicit relativistic quark model calculation. A comparison of our results with the results of other calculations is performed.Comment: 31 pages Latex (uses epsf, revtex). Section II expanded, typos corrected. This version will appear in Phys. Rev.

    Large palaeophiid and nigerophiid snakes from Paleogene Trans-Saharan Seaway deposits of Mali

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    The Paleogene was a time of high diversity for snakes, and was characterized by some of the largest species known to have existed. Among these snakes were pan-Tethyan marine species of Nigerophiidae and Palaeophiidae. The latter family included the largest sea snake, Palaeophis colossaeus, known from the Trans-Saharan Seaway of Mali during the Eocene. This paper describes new material collected from Malian Trans-Saharan Seaway deposits, including additional material of Palaeophis colossaeus, a new, large species of nigerophiid, Amananulam sanogoi gen. et sp. nov., and a medium-sized snake of indeterminate affinities. The material provides new information on the intracolumnar variation of the vertebral column in Palaeophis colossaeus. We estimate the total length of each species by regression of vertebral measurements on body size. Both Palaeophis colossaeus and Amananulam sanogoi gen. et sp. nov. are the largest or among the largest members of their respective clades. The large size of Tethyan snakes may be indicative of higher temperatures in the tropics than are present today

    Integral Field Spectroscopy of a peculiar Supernova Remnant MF16 in NGC6946

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    We present a study of a peculiar Supernova Remnant MF16, associated with the Ultraluminous X-ray Source (ULX) NGC6946 ULX-1. Observations were taken with the MultiPupil Fiber Spectrograph (MPFS) with 6-m telescope on January 2005. The nebula is found to be highly asymmetric, one of the parts being much denser and colder. The two-component structure of the emission lines and radial velocity gradient argue for a non-spherical nebula, expanding with a velocity of about 100 km/s. Neither shock models nor the X-ray emission can adequately explain the actual emission line spectrum of MF16, so we suggest an additional ultraviolet source with a luminosity of about 10E40 erg/s. We confirm coincidence of the ULX with the central star, and identify radio emission observed by VLA with the most dense part of the nebula.Comment: Proceedings of the ESO and Euro3D Workshop "Science Perspectives for 3D Spectroscopy", Garching (Germany), October 10-14, 2005. M. Kissler-Patig, M.M. Roth and J.R. Walsh (eds.

    Aviation English Assessment and Training

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    Due to a significant global increase in demand for air travel, there has been a corresponding increase in demand for ab initio flight training. Thousands of international flight students seek admission to collegiate aviation programs in the United States and Canada every year. These international flight students come to the United States and Canada because flight training is nonexistent in their native countries. In fact, flight training in most of these countries is impossible due to airspace restrictions and onerous regulations. If there is flight training available in these countries, the cost is usually prohibitive compared to the cost in the United States and Canada. The requirements and recommendations for international aeronautical communications is described in the International Civil Aviation Organization (ICAO) Annex 10, Volume II which establishes the English language as the de facto language of international aviation. The majority of these international flight students are non-native English speakers (NNES) which can make it difficult for them to succeed in an already challenging academic environment. Inadequate English language proficiency is also a significant safety issue. Unfortunately, there are very few aviation English assessment programs available to evaluate NNES flight students for aviation English proficiency. There are also very few aviation English training programs available for those who are unable to demonstrate proficiency. This research seeks to answer two questions: Does inadequate aviation English proficiency continue to be a flight safety issue? Has compliance with the ICAO Language Proficiency Requirements (LPRs) helped, or has it contributed to this problem
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