32,859 research outputs found
A morphometric analysis of isolated Torpedo electric organ synaptic vesicles following stimulation.
On-board timeline validation and repair : a feasibility study
We report on the progress and outcome of a recent ESAfunded project (MMOPS) designed to explore the feasibility of on-board reasoning about payload timelines. The project sought to examine the role of on-board timeline reasoning and the operational context into which it would fit. We framed a specification for an on-board service that fits with existing practices and represents a plausible advance within sensible constraints on the progress of operations planning. We have implemented a prototype to demonstrate the feasibility of such a system and have used it to show how science gathering operations might be improved by its deployment
Nu sub 1 plus nu sub 3 combination band of SO2
The infrared-active vibration-rotation combination band nu sub 1 + nu sub 3 of sulfur dioxide was measured with moderately high spectral resolution. Quantum number identifications of spectral lines were made by comparison with theoretically computed spectra which include the effects of centrifugal distortion. Relative line intensities were also calculated. The band center for nu sub 1 + nu sub 3 was determined to be 2499.60 + or - 0.10/cm
Fundamental bands of S(32)O2(16)
The infrared-active vibration-rotation fundamentals of sulfur dioxide were measured with moderately high spectral resolution. Quantum number assignments were made for spectral lines from J = O to 57, by comparison with theoretically computed spectra which include the effects of centrifugal distortion. The following values for the band centers were determined: nu sub 1 = 1151.65 + or - 0.10/cm, nu sub 2 = 517.75 + or - 0.10/cm, and nu sub 3 = 1362.00 + or - 0.10/cm. Intensities of the observed lines have also been computed. Dipole moment derivatives were obtained
RAT0455+1305: another pulsating hybrid sdB star
RAT0455+1305 was discovered during the Rapid Temporal Survey which aims in
finding any variability on timescales of a few minutes to several hours. The
star was found to be another sdBV star with one high amplitude mode and
relatively long period. These features along with estimation of T_eff and log g
makes this star very similar to Balloon 090100001. Encouraged by prominent
results obtained for the latter star we have decided to perform white light
photometry on RAT0455+1305. In 2009 we used the 1.5m telescope located in San
Pedro Martir Observatory in Mexico. Fourier analysis confirmed the dominant
mode found in the discovery data, uncovered another peak close to the dominant
one, and three peaks in the low frequency region. This shows that RAT0455+1305
is another hybrid sdBV star pulsating in both p- and g-modes.Comment: Proceedings of The Fourth Meeting on Hot Subdwarf Stars and Related
Objects held in China, 20-24 July 2009. Accepted for publication in
Astrophysics & Space Scienc
On small homotopies of loops
Two natural questions are answered in the negative:
(1) If a space has the property that small nulhomotopic loops bound small
nulhomotopies, then are loops which are limits of nulhomotopic loops themselves
nulhomotopic?
(2) Can adding arcs to a space cause an essential curve to become
nulhomotopic?
The answer to the first question clarifies the relationship between the
notions of a space being homotopically Hausdorff and -shape injective.Comment: 12 pages, 5 figure
Understanding Pound-Drever-Hall locking using voltage controlled radio-frequency oscillators: An undergraduate experiment
We have developed a senior undergraduate experiment that illustrates
frequency stabilization techniques using radio-frequency electronics. The
primary objective is to frequency stabilize a voltage controlled oscillator to
a cavity resonance at 800 MHz using the Pound-Drever-Hall method. This
technique is commonly applied to stabilize lasers at optical frequencies. By
using only radio-frequency equipment it is possible to systematically study
aspects of the technique more thoroughly, inexpensively, and free from eye
hazards. Students also learn about modular radio-frequency electronics and
basic feedback control loops. By varying the temperature of the resonator,
students can determine the thermal expansion coefficients of copper, aluminum,
and super invar.Comment: 9 pages, 10 figure
Complying With Feed Additive and Drug Withdrawl Periods
Most drugs are accumulated in excretory organs such as the kidneys and liver , and they are found in higher levels for a longer time in these organs than in other tissue. Due to a continuous excretion of the drugs from these organs, tissue levels are usually rapidly reduced after the drug is no longer fed or injected. The rate of excretion of a drug and its end products from animal tissues must be established before it can be considered for approval by the Food and Drug Administration. Then withdrawal periods that are sufficiently long enough to permit complete or near complete elimination of the drug from animal tissues , milk or eggs are established. Once a feed additive is approved it means that the FDA considers it completely safe for use in animal feeds without unsafe levels of residues occurring in the animal tis sue or its products if the withdrawal period is observed and it is fed at recommended levels
Multi-filter transit observations of WASP-39b and WASP-43b with three San Pedro M\'artir telescopes
Three optical telescopes located at the San Pedro M\'artir National
Observatory were used for the first time to obtain multi-filter defocused
photometry of the transiting extrasolar planets WASP-39b and WASP-43b. We
observed WASP-39b with the 2.12m telescope in the U filter for the first time,
and additional observations were carried out in the R and I filters using the
0.84m telescope. WASP-43b was observed in VRI with the same instrument, and in
the i filter with the robotic 1.50m telescope. We reduced the data using
different pipelines and performed aperture photometry with the help of custom
routines, in order to obtain the light curves. The fit of the light curves
(1.5--2.5mmag rms), and of the period analysis, allowed a revision of the
orbital and physical parameters, revealing for WASP-39b a period ( days) which is seconds larger than
previously reported. Moreover, we find for WASP-43b a planet/star radius
() which is larger in the i filter
with respect to previous works, and that should be confirmed with additional
observations. Finally, we confirm no evidence of constant period variations in
WASP-43b.Comment: 13 pages, 7 figures, accepted in PASP, scheduled for the February 1,
2015 issu
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