13,701 research outputs found
The communications technology satellite and the associated ground terminals for experiments
General spacecraft operational characteristics of the Communications Technology Satellite are discussed with particular emphasis on communication system parameters. Associated used ground terminals are reviewed. Wideband communications are also discussed
The effect of expository writing as a pre-reading activity on comprehension of expository text
The purpose of this study was to examine the effect of a pre-reading expository writing task on comprehension of expository text. It was undertaken in order to ascertain the usefulness of writing as a pre-reading activity in the development of schema theoretic reading teaching strategies. The theoretical position of the study was that writing before reading would activate prior knowledge in the form of content and structure in the working memory of the reader and thereby enhance reading comprehension. The sample, comprised selected from a small, of 51 year 6/7 students, school in the outskirts of was the metropolitan area. These students were systematically allocated to one of three equivalent groups on the basis of standardised reading comprehension test results. The experiment followed a three group, post-test only design, with two control groups and one experimental. The experimental group participated in a 20 minute writing activity on the topic of animal conservation. One control group participated in a writing activity on the topic of television”, while the other control participated iq maths activities, i.e., they did not write, At the conclusion of this 20 minute session, all groups read a text about animal conservation then completed a probe question comprehension test containing explicit and inferential questions relating to the text. The results of the short answer test were quantified in two sections, i.e., responses to explicit questions and responses to inferential questions, and the results were analysed by one way analysis of variance
COMPETITIVE GRANTS AND THE FUNDING OF AGRICULTURAL RESEARCH IN THE U.S.
To increase the efficiency of the public agricultural R&D system, expanded use of competitive grants to fund state institutions has been advocated. This paper characterizes different funding instruments and empirically assesses the effects of changes in mechanism use. Factors associated with greater levels of competitive grants are modeled.Research and Development/Tech Change/Emerging Technologies,
Electron Spin Precession at CEBAF
The nuclear physics experiments at the Thomas Jefferson National Accelerator
Facility often require longitudinally polarized electrons to be simultaneously
delivered to three experimental halls. The degree of longitudinal polarization
to each hall varies as function of the accelerator settings, making it
challenging in certain situations to deliver a high degree of longitudinal
polarization to all the halls simultaneously. Normally, the degree of
longitudinal polarization the halls receive is optimized by changing the
initial spin direction at the beginning of the machine with a Wien filter.
Herein, it is shown that it is possible to further improve the degree of
longitudinal polarization for multiple experimental halls by redistributing the
energy gain of the CEBAF linacs while keeping the total energy gain fixed.Comment: 4 pages, 3 figures, to appear in the proceedings of the 18th
International Symposium on Spin Physics (SPIN2008
Control System for the LEDA 6.7-MeV Proton Beam Halo Experiment
Measurement of high-power proton beam-halo formation is the ongoing
scientific experiment for the Low Energy Demonstration Accelerator (LEDA)
facility. To attain this measurement goal, a 52-magnet beam line containing
several types of beam diagnostic instrumentation is being installed. The
Experimental Physics and Industrial Control System (EPICS) and commercial
software applications are presently being integrated to provide a real-time,
synchronous data acquisition and control system. This system is comprised of
magnet control, vacuum control, motor control, data acquisition, and data
analysis. Unique requirements led to the development and integration of
customized software and hardware. EPICS real-time databases, Interactive Data
Language (IDL) programs, LabVIEW Virtual Instruments (VI), and State Notation
Language (SNL) sequences are hosted on VXI, PC, and UNIX-based platforms which
interact using the EPICS Channel Access (CA) communication protocol.
Acquisition and control hardware technology ranges from DSP-based diagnostic
instrumentation to the PLC-controlled vacuum system. This paper describes the
control system hardware and software design, and implementation.Comment: LINAC2000 Conference, 4 pg
Electronic Structures of Nitridomanganese(V) Complexes
The single-crystal polarized absorption and circular dichroism spectra of the nitridomanganese(V) complexes (salen)Mn⋮N (1), (1S,2S-(−)-saldpen)Mn⋮N (2), and (1R,2R-(+)-saldpen)Mn⋮N (3) have been measured [salen = N,N‘-ethylenebis(salicylideneaminato) dianion, 1S,2S-(−)-saldpen = N,N‘-(1S,2S-(−)-diphenyl)ethylenebis(salicylideneaminato) dianion, and 1R,2R-(+)-saldpen = N,N‘-(1R,2R-(+)-diphenyl)ethylenebis(salicylideneaminato) dianion]. As revealed by X-ray crystal structure analyses, these molecules have a distorted square-pyramidal geometry with a short Mn⋮N bond distance (1.52(3) Å for 2). The Cs compounds have a low-spin^ 1A‘[a‘(x^2 − y^2)]^2 ground state. The lowest absorption system (∼600 nm) consists of two components that are separated by approximately 4000 cm^(-1); these are assigned to ^1A‘ → ^1A‘[a‘(x^2 − y^2)a‘(yz)] (14 900 cm^(-1)) and ^1A‘ → ^1A‘‘[a‘(x^2 − y^2)a‘‘(xz)] (18 900 cm^(-1)) transitions
Calculating the virtual cohomological dimension of the automorphism group of a RAAG
We describe an algorithm to find the virtual cohomological dimension of the
automorphism group of a right-angled Artin group. The algorithm works in the
relative setting; in particular it also applies to untwisted automorphism
groups and basis-conjugating automorphism groups. The main new tool is the
construction of free abelian subgroups of certain Fouxe-Rabinovitch groups of
rank equal to their virtual cohomological dimension, generalizing a result of
Meucci in the setting of free groups.Comment: 15 pages, 2 figures. Revised background on RORGs, small changes
elsewhere. Accepted to appear in Bulletin of the LM
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