13,341 research outputs found

    Relativistic models of the universe with pressure equal to zero and time-dependent uniformity

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    Zero density and approximate, relativistic models of univers

    Preliminary study of a possible automatic landing system

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    Navigation and control laws for a possible automatic landing system have been investigated. The system makes use of data from an inertial table and either an airborne or ground radar to generate signals that guide the airplane to a landing. All landing maneuvers take place within a zone that extends 6000 m out from the touchdown point, 4000 m on each side of the runway center line, and 540 m high. The results show that the system can adequately control the airplane on steep, curved decelerating approaches to a landing that takes place with small errors from the desired landing point and desired airplane attitude. The system studied would interface well with the scanning beam microwave landing system (MLS). The use of this system with the MLS makes it possible to incorporate an independent landing monitor

    Electronic management of assessment – administrative perspectives

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    Book synopsis: In 2014, the Bloomsbury Learning Environment (BLE) Consortium initiated a wide-ranging, two-year-long research and dissemination project focusing on the use of technology in assessment and feedback. Our aim was to understand and improve processes, practices, opportunities and tools available to the institutional members of the BLE Consortium. From the project, we produced three research papers investigating current practice and 21 case studies describing both technology-enabled pedagogy and technical development. Now presented as a free ebook, co-edited by Leo Havemann and Sarah Sherman, we offer the flavour of the variety and breadth of the BLE?s activities relating to the project theme as a contribution to the education sector?s widening conversation about the interplay of assessment, feedback, pedagogy and technology

    Contextualising the electronic management of assessment lifecycle in Bloomsbury

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    Book synopsis: In 2014, the Bloomsbury Learning Environment (BLE) Consortium initiated a wide-ranging, two-year-long research and dissemination project focusing on the use of technology in assessment and feedback. Our aim was to understand and improve processes, practices, opportunities and tools available to the institutional members of the BLE Consortium. From the project, we produced three research papers investigating current practice and 21 case studies describing both technology-enabled pedagogy and technical development. Now presented as a free ebook, co-edited by Leo Havemann and Sarah Sherman, we offer the flavour of the variety and breadth of the BLE?s activities relating to the project theme as a contribution to the education sector?s widening conversation about the interplay of assessment, feedback, pedagogy and technology

    Asymptotic statistical properties of AR spectral estimators for processes with mixed spectra

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    Copyright © 2002 IEEEThe influence of a point spectrum on large sample statistics of the autoregressive (AR) spectral estimator is addressed. In particular, the asymptotic distributions of the AR coefficients, the innovations variance, and the spectral density estimator of a finite-order AR(p) model to a mixed spectrum process are presented. Various asymptotic results regarding AR modeling of a regular process with a continuous spectrum are arrived at as special cases of the results for the mixed spectrum setting. Finally, numerical simulations are performed to verify the analytical resultsSoon-Sen Lau, P. J. Sherman and L. B. Whit

    Molecular Dynamics Simulations of the O-glycosylated 21-residue MUC1 Peptides

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    The conformational propensities of the 21-residue peptide and its Oglycosylated analogs were studied by molecular dynamics (MD) simulations. This polypeptide motif comprises the tandem repeat of the human mucin (MUC1) protein core that is differently glycosylated in normal and cancer cells. To evaluate the structural effects of O-glycosylation on the polypeptide backbone, conformations of the nonglycosylated peptide and its glycosylated analogs were monitored during the 1 ns MD simulations. Radius gyration for whole peptide and its fragments, as well as root-mean-square-deviation between coordinate sets of the backbone atoms of starting structures and generated structures, were calculated. It was shown that O-glycosylation promotes and stabilizes the extended conformations of the whole peptide and its central PDTRP fragment. O-glycosylation of the specific Thr residues significantly affects the conformational distributions of the flanking Ser residues. It was also shown that Oglycosylation promoted backbone conformations of the immunodominant region PDTRP that were similar to the structural features of the peptides presented by the major histocompatability complex (MHC) to T-cell receptors Keywords: glycoprotein MUC1, glycopeptides, molecular dynamics, conformations

    Introduction

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    In 2014, the Bloomsbury Learning Environment (BLE) Consortium initiated a wide-ranging, two-year-long research and dissemination project focusing on the use of technology in assessment and feedback. Our aim was to understand and improve processes, practices, opportunities and tools available to the institutional members of the BLE Consortium. From the project, we produced three research papers investigating current practice and 21 case studies describing both technology-enabled pedagogy and technical development. Now presented as a free ebook, co-edited by Leo Havemann and Sarah Sherman, we offer the flavour of the variety and breadth of the BLE's activities relating to the project theme as a contribution to the education sector's widening conversation about the interplay of assessment, feedback, pedagogy and technology

    Structure of Weak Shock Waves in a Monatomic Gas

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    The profiles and thicknesses of normal shock waves in argon at Mach numbers of 1.335, 1.454, 1.576, and 1-713 were determined experimentally by means of a free-molecule probe whose equilibrium temperature is related by kinetic theory to the local flow properties and their gradients. Comparisons were made between the experimental shock profiles and the theoretical profiles calculated from the Navier-Stokes equations, the Grad 13-moment equations, and the Burnett equations. New, very accurate numerical integrations of the Burnett equations were obtained for this purpose with results quite different from those found by Zoller, to whom the solution of this problem is frequently attributed. The experimental shock profiles were predicted with approximately equal success by the Navier-Stokes and Burnett theories, while the 13-moment method was definitely less satisfactory. A surprising feature of the theoretical results is the relatively small difference in predictions between the Navier-Stokes and Burnett theories in the present range of shock strengths and the contrastingly large difference between predictions of Burnett and the 13-moment theories. It is concluded that the Navier-Stokes equations are correct for weak shocks and that within the present shock strength range the Burnett equations make no improvement which merits the trouble of solving them. For shocks of noticeably greater strength, say with a shock Mach number of more than 2.5, it remains fundamentally doubtful that any of these theories can be correct

    Pupillometry, a bioengineering overview

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    The pupillary control system is examined using a microprocessor based integrative pupillometer. The real time software functions of the microprocessor include: data collection, stimulus generation and area to diameter conversion. Results of an analysis of linear and nonlinear phenomena are presented
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