135,068 research outputs found
TTF: a flexible approach to narrowband imaging
The Taurus Tunable Filter (TTF) is a tunable narrowband interference filter
covering wavelengths from 6300 A to the sensitivity drop-off of conventional
CCDs (9600 A), although a blue `arm' (3700-6500 A) is to be added by the end of
1997. The TTF offers monochromatic imaging at the cassegrain foci of both the
Anglo-Australian and William Herschel Telescopes, with an adjustable passband
of between 6 and 60 A. In addition, frequency switching with the TTF can be
synchronized to movement of charge (charge shuffling) on the CCD which has many
important applications in astrophysics. Here we review different modes of TTF.
We maintain a web site at http://msowww.anu.edu.au/~dhj/ttf.html describing all
aspects of TTF and its operation. In addition to general use, the instrument is
available in AAT service time. Details can be found at
http://www.aao.gov.au/local/www/jmc/service/service.html.Comment: 8 pages; Latex; 5 encapsulated postscript figures. Invited talk at
the "AAO/UKST Galactic Plane H-alpha Survey", International Workshop, Sydney,
Australi
The effectiveness of an oculometer training tape on pilot and copilot trainees in a commercial flight training program
A study was designed to evaluate the effectiveness of a video tape detailing the various aspects of instrument scanning by experienced pilots on performance by pilots and copilots undergoing flight training in a Boeing 737 flight simulator. The performance ratings by instructor pilots (IP's) and self-reported instrument scan behavior by trainees were compared with those of a control group. The results indicated that the training tape had little or no effect on performance by trainees in the experimental group. Feedback from the IP's and trainees suggested that a feedback strategy providing each trainee's individual instrument scan behavior might be more beneficial in flight training than the general instructional strategy of the oculometer training tape. Flight training personnel and trainees' reports of performance decrements on or around the third day of flight simulator training were investigated. The IP's performance ratings of 27 pilot and copilot trainees failed to reveal a systematic performance decrement; however, feedback from the trainees revealed that their own attribution of performance decrements was associated with the order in which their training occurred within a session. Further research was suggested
The effectiveness of incorporating a real-time oculometer system in a commercial flight training program
The effectiveness of incroporating a real-time oculometer system into a Boeing 737 commercial flight training program was studied. The study combined a specialized oculometer system with sophisticated video equipment that would allow instructor pilots (IPs) to monitor pilot and copilot trainees' instrument scan behavior in real-time, and provide each trainee with video tapes of his/her instrument scanning behavior for each training session. The IPs' performance ratings and trainees' self-ratings were compared to the performance ratings by IPs and trainees in a control group. The results indicate no difference in IP ratings or trainees' self-ratings for the control and experimental groups. The results indicated that the major beneficial role of a real-time oculometer system for pilots and copilots having a significant amount of flight experience would be for problem solving or refinement of instrument scanning behavior rather than a general instructional scheme. It is suggested that this line of research be continued with the incorporation of objective data (e.g., state of the aircraft data), measures of cost effectiveness and with trainees having less flight experience
The effectiveness of incorporating a real-time oculometer system in a commercial flight training program
The effectiveness on pilot and trainee performance and scanning behavior of incorporating a real time oculometer system in a commerical flight training program was assessed. Trainees received simulator training in pairs requiring the trainees to alternate the order of training within a session. The 'third day phenomenon' of performance decrement was investigated, including the role of order of training on performance
Biaxial tests of flat graphite/epoxy laminates
The influence of biaxially applied loads on the strength of composite materials containing holes was analyzed. The analysis was performed through the development of a three dimensional, finite element computer program that is capable of evaluating fiber breakage, delamination, and matrix failure. Realistic failure criteria were established for each of the failure modes, and the influence of biaxial loading on damage accumulation under monotonically increasing loading was examined in detail. Both static and fatigue testing of specially designed biaxial specimens containing central holes were performed. Static tests were performed to obtain an understanding of the influence of biaxial loads on the fracture strength of composite materials and to provide correlation with the analytical predictions. The predicted distributions and types of damage are in reasonable agreement with the experimental results. A number of fatigue tests were performed to determine the influence of cyclic biaxial loads on the fatigue life and residual strength of several composite laminates
Benchmark ultra-cool dwarfs in widely separated binary systems
Ultra-cool dwarfs as wide companions to subgiants, giants, white dwarfs and
main sequence stars can be very good benchmark objects, for which we can infer
physical properties with minimal reference to theoretical models, through
association with the primary stars. We have searched for benchmark ultra-cool
dwarfs in widely separated binary systems using SDSS, UKIDSS, and 2MASS. We
then estimate spectral types using SDSS spectroscopy and multi-band colors,
place constraints on distance, and perform proper motions calculations for all
candidates which have sufficient epoch baseline coverage. Analysis of the
proper motion and distance constraints show that eight of our ultra-cool dwarfs
are members of widely separated binary systems. Another L3.5 dwarf, SDSS 0832,
is shown to be a companion to the bright K3 giant Eta Cancri. Such primaries
can provide age and metallicity constraints for any companion objects, yielding
excellent benchmark objects. This is the first wide ultra-cool dwarf + giant
binary system identified.Comment: 4 pages, 3 figures, conference, "New Technologies for Probing the
Diversity of Brown Dwarfs and Exoplanets", oral tal
Biodetection grinder
Work on a biodetection grinder is summarized. It includes development of the prototype grinder, second generation grinder, and the production version of the grinder. Tests showed the particle size distribution was satisfactory and biological evaluation confirmed the tests
Can children withhold consent to treatment
A dilemma exists when a doctor is faced with a child or young person who refuses medically indicated treatment. The Gillick case has been interpreted by many to mean that a child of sufficient age and intelligence could validly consent or refuse consent to treatment. Recent decisions of the Court of Appeal on a child's refusal of medical treatment have clouded the issue and undermined the spirit of the Gillick decision and the Children Act 1989. It is now the case that a child patient whose competence is in doubt will be found rational if he or she accepts the proposal to treat but may be found incompetent if he or she disagrees. Practitioners are alerted to the anomalies now exhibited by the law on the issue of children's consent and refusal. The impact of the decisions from the perspectives of medicine, ethics, and the law are examined. Practitioners should review each case of child care carefully and in cases of doubt seek legal advice
Spectral analysis of the barium central star of the planetary nebula Hen 2-39
Barium stars are peculiar red giants characterized by an overabundance of
s-process elements along with an enrichment in carbon. These stars are
discovered in binaries with white dwarf companions. The more recently formed of
these stars are still surrounded by a planetary nebula. Precise abundance
determinations of the various s-process elements, especially, of the lightest,
short-lived radionuclide technetium will establish constraints for the
formation of s-process elements in asymptotic giant branch stars as well as
mass transfer through, for example, stellar wind, Roche-lobe overflow, and
common-envelope evolution. We performed a detailed spectral analysis of the
K-type subgiant central star of the planetary nebula Hen 2-39 based on
high-resolution optical spectra obtained with the Ultraviolet and Visual
Echelle Spectrograph at the Very Large Telescope using LTE model atmospheres.
We confirm the effective temperature of K for
the central star of the planetary nebula Hen 2-39. It has a photospheric carbon
enrichment of and a barium overabundance of
. We find a deficiency for most of the
iron-group elements (calcium to iron) and establish an upper abundance limit
for technetium (). The quality of the
available optical spectra is not sufficient to measure abundances of all
s-process elements accurately. Despite large uncertainties on the abundances as
well as on the model yields, the derived abundances are most consistent with a
progenitor mass in the range 1.75-3.00 and a metallicity of
. This result leads to the conclusion that the
formation of such systems requires a relatively large mass transfer that is
most easily obtained via wind-Roche lobe overflow.Comment: 26 pages, 18 figure
Can a strongly interacting Higgs boson rescue SU(5)?
Renormalization group analyses show that the three running gauge coupling
constants of the Standard Model do not become equal at any energy scale. These
analyses have not included any effects of the Higgs boson's self-interaction.
In this paper, I examine whether these effects can modify this conclusion.Comment: 8 pages (plus 4 postscript figures
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