2,721 research outputs found
Psychophysical Research in Development of a Fiber-optic Helmet Mounted Display
The Fiber Optic Helmet Mounted Display (FOHMD) was conceived as an innovative solution to existing flight simulator display deficiencies. An initial (breadboard) version of the system was fabricated to permit experimentation which would help define design requirements for a more refined engineering prototype. A series of visual/human factors studies are being conducted at the USAF Human Resources Laboratory (AFHRL) Operations Training Division, Williams AFB, Arizona to determine the optimum fit of human observer operating characteristics and fiber optic helmet mounted display technology. Pilot performance within a variety of high resolution insert/binocular overlap combinations is being assessed in two classes of environment. The first two of four studies planned incorporate an air-to-air combat environment, whereas the second two studies will use a low level environment with air to ground weapons delivery
Multi-axis control of telemanipulators
The development of multi-axis hand controllers for use in telemanipulator systems is described. Experience in the control of the SRMS (shuttle remote manipulator system) arm is reviewed together with subsequent tests involving a number of simulators and configurations, including use as a side-arm flight control for helicopters. The factors affecting operator acceptability are reviewed
First detection of bromine and antimony in hot stars
Bromine (atomic number Z=35) and antimony (Z=51) are extremely difficult to
detect in stars. In very few instances, weak and mostly uncertain
identifications of Br I, Br II, and Sb II in relatively cool, chemically
peculiar stars were successful. Adopted solar abundance values rely on
meteoritic determinations. Here, we announce the first identification of these
species in far-ultraviolet spectra of hot stars (with effective temperatures of
49,500-70,000 K), namely in helium-rich (spectral type DO) white dwarfs. We
identify the Br VI resonance line at 945.96 A. A previous claim of Br detection
based on this line is incorrect because its wavelength position is inaccurate
by about 7 A in atomic databases. Taking advantage of precise laboratory
measurements, we identify this line as well as two other, subordinate Br VI
lines. Antimony is detected by the Sb V resonance doublet at 1104.23/1225.98 A,
as well as two subordinate Sb VI lines. A model-atmosphere analysis reveals
strongly oversolar Br and Sb abundances that are caused by radiative-levitation
dominated atomic diffusion.Comment: Accepted for publication in A&
Mineralocorticoid receptor blockade during a rat's first violent encounter inhibits its subsequent propensity for violence.
In individuals naive to serious conflict in an unfamiliar environment, violence has long-lasting effects on subsequent aggressive behavior. This effect of the stressful experience of a first violent conflict occurs in victims as well as offenders. The authors study in the male rat as offender the role of a rapid corticosterone signal mediated by brain mineralocorticoid receptors (MR) in adjusting the threshold of aggressive responses. For this purpose, the authors have applied electrical stimulation of the brain's aggression circuit via the hypothalamic attack area or HAA. Using this paradigm, they found that in inexperienced rats, retesting of the animals on subsequent days facilitated aggression. Hypothalamic attack thresholds decreased to about 50% of their initial level. However, blocking the MR once with the mineralocorticoid antagonist spironolactone, during the very first evoked attacks, permanently prevented attack facilitation in subsequent conflicts in that same environment. The MR-mediated effect blocked by the antagonist occurred within an hour following the start of the first aggression tests only. A later MR blockade was not effective. These findings suggest that the corticosterone stress response during a very first serious conflict initializes an enhanced propensity for violent aggression through the brain MR
JDATAVIEWER â JAVA-Based Charting Library
The JDataViewer is a Java-based charting library developed at CERN, with powerful, extensible and easy to use function editing capabilities. Function edition is heavily used in Control System applications, but poorly supported in products available on the market. The JDataViewer enables adding, removing and modifying function points graphically (using a mouse) or by editing a table of values. Custom edition strategies are supported: developer can specify an algorithm that reacts to the modification of a given point in the function by automatically adapting all other points. The library provides all typical 2D plotting types (scatter, polyline, area, bar, HiLo, contour), as well as data point annotations and data indicators. It also supports common interactors to zoom and move the visible view, or to select and highlight function segments. A clear API is provided to configure and customize all chart elements (colors, fonts, data ranges ...) programmatically, and to integrate non-standard rendering types, interactors or chart decorations (custom drawings). Last but not least, the library offers class-leading performance
Stellar laboratories. IX. New Se V, Sr IV - VII, Te VI, and I VI oscillator strengths and the Se, Sr, Te, and I abundances in the hot white dwarfs G191-B2B and RE 0503-289
To analyze spectra of hot stars, advanced non-local thermodynamic equilibrium
(NLTE) model-atmosphere techniques are mandatory. Reliable atomic data is for
the calculation of such model atmospheres.
We aim to calculate new Sr IV - VII oscillator strengths to identify for the
first time Sr spectral lines in hot white dwarf (WD) stars and to determine the
photospheric Sr abundances. o measure the abundances of Se, Te, and I in hot
WDs, we aim to compute new Se V, Te VI, and I VI oscillator strengths.
To consider radiative and collisional bound-bound transitions of Se V, Sr IV
- VII, Te VI, and I VI in our NLTE atmosphere models, we calculated oscillator
strengths for these ions.
We newly identified four Se V, 23 Sr V, 1 Te VI, and three I VI lines in the
ultraviolet (UV) spectrum of RE0503-289. We measured a photospheric Sr
abundance of 6.5 +3.8/-2.4 x 10**-4 (mass fraction, 9500 - 23800 times solar).
We determined the abundances of Se (1.6 +0.9/-0.6 x 10**-3, 8000 - 20000), Te
(2.5 +1.5/-0.9 x 10**-4, 11000 - 28000), and I (1.4 +0.8/-0.5 x 10**-5, 2700 -
6700). No Se, Sr, Te, and I line was found in the UV spectra of G191-B2B and we
could determine only upper abundance limits of approximately 100 times solar.
All identified Se V, Sr V, Te VI, and I VI lines in the UV spectrum of
RE0503-289 were simultaneously well reproduced with our newly calculated
oscillator strengths.Comment: 26 pages, 5 figure
BD-22 3467, a DAO-type star exciting the nebula Abell 35
Spectral analyses of hot, compact stars with NLTE (non-local thermodynamical
equilibrium) model-atmosphere techniques allow the precise determination of
photospheric parameters. The derived photospheric metal abundances are crucial
constraints for stellar evolutionary theory.
Previous spectral analyses of the exciting star of the nebula A 35, BD-22
3467, were based on He+C+N+O+Si+Fe models only. For our analysis, we use
state-of-the-art fully metal-line blanketed NLTE model atmospheres that
consider opacities of 23 elements from hydrogen to nickel. For the analysis of
high-resolution and high-S/N (signal-to-noise) FUV (far ultraviolet, FUSE) and
UV (HST/STIS) observations, we combined stellar-atmosphere models and
interstellar line-absorption models to fully reproduce the entire observed UV
spectrum.
The best agreement with the UV observation of BD-22 3467 is achieved at Teff
= 80 +/- 10 kK and log g =7.2 +/- 0.3. While Teff of previous analyses is
verified, log g is significantly lower. We re-analyzed lines of silicon and
iron (1/100 and about solar abundances, respectively) and for the first time in
this star identified argon, chromium, manganese, cobalt, and nickel and
determined abundances of 12, 70, 35, 150, and 5 times solar, respectively. Our
results partially agree with predictions of diffusion models for DA-type white
dwarfs. A combination of photospheric and interstellar line-absorption models
reproduces more than 90 % of the observed absorption features. The stellar mass
is M ~ 0.48 Msun.
BD-22 3467 may not have been massive enough to ascend the asymptotic giant
branch and may have evolved directly from the extended horizontal branch to the
white dwarf state. This would explain why it is not surrounded by a planetary
nebula. However, the star, ionizes the ambient interstellar matter, mimicking a
planetary nebula.Comment: 13 pages, 17 figure
Status Report of the Measurement Service for the CERN Accelerator Logging
The LHC (Large Hadron Collider) Logging service is aimed to satisfy the requirement of capturing and storing any relevant accelerator data to track its variation over time. This service is presently operational on the whole CERN accelerator complex, from ion and proton sources to LHC, and has become a critical component of the CERN control systems. The focus is given to the measurement part of this service, which is responsible for the data acquisition and preparation (processing, filtering, concentration) prior to its storage in database and file systems. Incoming data is often processed by a concentration layer, the processes that transform data of multiple devices into single values according to well defined rules and then publish them further on, to the LHC Logging among others. The paper describes the architecture and presents the solutions to the very challenging requirements imposed by the LHC in terms of overall performance and reliability. The efficiency of the data acquisition and filtering as well as the flexible software design are highlighted
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