4,331 research outputs found
A description of the software analysis from flight and simulation data of the course cut limiter in the TCV b-737 area navigation computer
During automatic horizontal path captures, the (Terminal Configured Vehicle) B-737 airplane maintained smaller than designed path intercept angles and experienced a sawtooth bank angle oscillation during its turn towards the path. From flight data, it was determined that these anomalies were caused by the improper output of the course cut limiter in the horizontal path control law. The output from the course cut limiter did not obtain its full value and it was calculated stepwise discontinuously. The automatic horizontal path captures were then conducted on the TCV B-737 airplane real-time simulation. The path intercept angles were maintained properly and no bank angle oscillation was encountered. Data showed that the course cut limiter was calculated at its full value in a continuous manner. The intermediate calculations of the course cut limiter in the airplane's navigation computer were rewritten and rescaled in such a manner that truncation errors could be minimized. The horizontal path capture tests were then reflown. The airplane maintained the proper path intercept angle and no bank angle oscillations occurred on any of the tests
Gamma-ray emission associated with Cluster-scale AGN Outbursts
Recent observations have revealed the existence of enormously energetic
~10^61 erg AGN outbursts in three relatively distant galaxy clusters. These
outbursts have produced bubbles in the intra-cluster medium, apparently
supported by pressure from relativistic particles and/or magnetic fields. Here
we argue that if > GeV particles are responsible then these particles are very
likely protons and nuclei, rather than electrons, and that the gamma-ray
emission from these objects, arising from the interactions of these hadrons in
the intra-cluster medium, may be marginally detectable with instruments such as
GLAST and HESS.Comment: 8 pages, 4 figures, accepted by MNRA
Decaying dark matter: a stacking analysis of galaxy clusters to improve on current limits
We show that a stacking approach to galaxy clusters can improve current
limits on decaying dark matter by a factor , with respect to a
single source analysis, for all-sky instruments such as Fermi-LAT. Based on the
largest sample of X-ray-selected galaxy clusters available to date (the MCXC
meta-catalogue), we provide all the astrophysical information, in particular
the astrophysical term for decaying dark matter, required to perform an
analysis with current instruments.Comment: 6 pages, 3 figures, supplementary file available on demand, accepted
for publication in PR
Attitude determination of the spin-stabilized Project Scanner spacecraft
Attitude determination of spin-stabilized spacecraft using star mapping techniqu
A simple model of unbounded evolutionary versatility as a largest-scale trend in organismal evolution
The idea that there are any large-scale trends in the evolution of biological organisms is highly controversial. It is commonly believed, for example, that there is a large-scale trend in evolution towards increasing complexity, but empirical and theoretical arguments undermine this belief. Natural selection results in organisms that are well adapted to their local environments, but it is not clear how local adaptation can produce a global trend. In this paper, I present a simple computational model, in which local adaptation to a randomly changing environment results in a global trend towards increasing evolutionary versatility. In this model, for evolutionary versatility to increase without bound, the environment must be highly dynamic. The model also shows that unbounded evolutionary versatility implies an accelerating evolutionary pace. I believe that unbounded increase in evolutionary versatility is a large-scale trend in evolution. I discuss some of the testable predictions about organismal evolution that are suggested by the model
Anger and predictors of drop-out from PTSD treatment of veterans and first responders.
Background: Drop-out is an important barrier in treating post-traumatic stress disorder (PTSD) with consequences that negatively impact clients, clinicians and mental health services as a whole. Anger is a common experience in people with PTSD and is more prevalent in military veterans. To date, no research has examined if anger may predict drop-out in military veterans or first responders.
Aims: The present study aimed to determine the variables that predict drop-out among individuals receiving residential treatment for PTSD.
Method: Ninety-five military veterans and first responders completed pre-treatment measures of PTSD symptom severity, depression, anxiety, anger, and demographic variables. Logistic regression analyses were used to determine if these variables predicted drop-out from treatment or patterns of attendance.
Results: Female gender was predictive of drop-out. However, when analysed by occupation female gender was predictive of drop-out among first responders and younger age was predictive of drop-out in military participants. Anger, depression, anxiety and PTSD symptom severity were not predictive of drop-out in any of the analyses. No variables were found to predict attendance patterns (consistent or inconsistent) or early versus late drop-out from the programme.
Conclusion: These results suggest that although anger is a relevant issue for treating PTSD, other factors may be more pertinent to drop-out, particularly in this sample. In contrast with other findings, female gender was predictive of drop-out in this study. This may indicate that in this sample, there are unique characteristics and possible interacting variables that warrant exploration in future research
The background from single electromagnetic subcascades for a stereo system of air Cherenkov telescopes
The MAGIC experiment, a very large Imaging Air Cherenkov Telescope (IACT)
with sensitivity to low energy (E < 100 GeV) VHE gamma rays, has been operated
since 2004. It has been found that the gamma/hadron separation in IACTs becomes
much more difficult below 100 GeV [Albert et al 2008] A system of two large
telescopes may eventually be triggered by hadronic events containing Cherenkov
light from only one electromagnetic subcascade or two gamma subcascades, which
are products of the single pi^0 decay. This is a possible reason for the
deterioration of the experiment's sensitivity below 100 GeV. In this paper a
system of two MAGIC telescopes working in stereoscopic mode is studied using
Monte Carlo simulations. The detected images have similar shapes to that of
primary gamma-rays and they have small sizes (mainly below 400 photoelectrons
(p.e.)) which correspond to an energy of primary gamma-rays below 100 GeV. The
background from single or two electromagnetic subcascdes is concentrated at
energies below 200 GeV. Finally the number of background events is compared to
the number of VHE gamma-ray excess events from the Crab Nebula. The
investigated background survives simple cuts for sizes below 250 p.e. and thus
the experiment's sensitivity deteriorates at lower energies.Comment: 15 pages, 7 figures, published in Journ.of Phys.
Development of a high-altitude airborne dial system: The Lidar Atmospheric Sensing Experiment (LASE)
The ability of a Differential Absorption Lidar (DIAL) system to measure vertical profiles of H2O in the lower atmosphere was demonstrated both in ground-based and airborne experiments. In these experiments, tunable lasers were used that required real-time experimenter control to locate and lock onto the atmospheric H2O absorption line for the DIAL measurements. The Lidar Atmospheric Sensing Experiment (LASE) is the first step in a long-range effort to develop and demonstrate an autonomous DIAL system for airborne and spaceborne flight experiments. The LASE instrument is being developed to measure H2O, aerosol, and cloud profiles from a high-altitude ER-2 (extended range U-2) aircraft. The science of the LASE program, the LASE system design, and the expected measurement capability of the system are discussed
Anomalous Noise in the Pseudogap Regime of YBaCuO
An unusual noise component is found near and below about 250 K in the normal
state of underdoped YBCO and Ca-YBCO films. This noise regime, unlike the more
typical noise above 250 K, has features expected for a symmetry-breaking
collective electronic state. These include large individual fluctuators, a
magnetic sensitivity, and aging effects. A possible interpretation in terms of
fluctuating charge nematic order is presented.Comment: 4 pages, 4 figure
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