11,237 research outputs found
Association of mid-infrared solar plages with Calcium K line emissions and magnetic structures
Solar mid-IR observations in the 8-15 micrometer band continuum with moderate
angular resolution (18 arcseconds) reveal the presence of bright structures
surrounding sunspots. These plage-like features present good association with
calcium CaII K1v plages and active region magnetograms. We describe a new
optical setup with reflecting mirrors to produce solar images on the focal
plane array of uncooled bolometers of a commercial camera preceded by germanium
optics. First observations of a sunspot on September 11, 2006 show a mid-IR
continuum plage exhibiting spatial distribution closely associated with CaII
K1v line plage and magnetogram structures. The mid-IR continuum bright plage is
about 140 K hotter than the neighboring photospheric regions, consistent with
hot plasma confined by the magnetic spatial structures in and above the active
regionComment: 5 pages, 4 figures. Accepted by PAS
Observations of OJ 287 from the Geodetic VLBI Archive of the Washington Correlator
We present 27 geodetic VLBI maps of OJ 287 obtained from the archive of the
Washington correlator. The observations presented here were made between 1990
October and 1996 December. During this period a sequence of six superluminal
components has been identified. We measured the proper motion of these
components to be approximately 0.5 mas/yr, which is about twice as high as that
seen in previous VLBI observations. These results imply a higher component
ejection rate than previously observed, in good agreement with the observed
occurrences of radio outbursts. We have examined a possible connection between
VLBI components and optical flares in the framework of a binary black hole
system.Comment: 9 pages, 5 included figures, emulateapj.sty, accepted to The
Astrophysical Journa
Short-lived solar burst spectral component at f approximately 100 GHz
A new kind of burst emission component was discovered, exhibiting fast and distinct pulses (approx. 60 ms durations), with spectral peak emission at f approx. 100 GHz, and onset time coincident to hard X-rays to within approx. 128 ms. These features pose serious constraints for the interpretation using current models. One suggestion assumes the f approx. 100 GHz pulses emission by synchrotron mechanism of electrons accelerated to ultrarelativistic energies. The hard X-rays originate from inverse Compton scattering of the electrons on the synchrotron photons. Several crucial observational tests are needed for the understanding of the phenomenon, requiring high sensitivity and high time resolution (approx. 1 ms) simultaneous to high spatial resolution (0.1 arcsec) at f approx. 110 GHz and hard X-rays
Enhanced Anandamide Plasma Levels in Patients with Complex Regional Pain Syndrome following Traumatic Injury: A Preliminary Report
The complex regional pain syndrome (CRPS) is a disabling neuropathic pain condition that may develop following injuries of the extremities. The pathogenesis of this syndrome is not clear; however, it includes complex interactions between the nervous and the immune system resulting in chronic inflammation, pain and trophic changes. This interaction may be mediated by chronic stress which is thought to activate the endogenous cannabinoid (endocannabinoid) system (ECS). We conducted an open, prospective, comparative clinical study to determine plasma level of the endocannabinoid anandamide by high-performance liquid chromatography and a tandem mass spectrometry system in 10 patients with CRPS type I versus 10 age- and sex-matched healthy controls. As compared to healthy controls, CRPS patients showed significantly higher plasma concentrations of anandamide. These results indicate that the peripheral ECS is activated in CRPS. Further studies are warranted to evaluate the role of the ECS in the limitation of inflammation and pain. Copyright (C) 2009 S. Karger AG, Base
The possible importance of synchrotron/inverse Compton losses to explain fast mm-wave and hard X-ray emission of a solar event
The solar burst of 21 May 1984, presented a number of unique features. The time profile consisted of seven major structures (seconds), with a turnover frequency of greater than or approximately 90 GHz, well correlated in time to hard X-ray emission. Each structure consisted of multiple fast pulses (0.1 seconds), which were analyzed in detail. A proportionality between the repetition rate of the pulses and the burst fluxes at 90 GHz and greater than or approximately 100 keV hard X-rays, and an inverse proportionality between repetition rates and hard X-ray power law indices were found. A synchrotron/inverse Compton model was applied to explain the emission of the fast burst structures, which appear to be possible for the first three or four structures
Comparison of averages of flows and maps
It is shown that in transient chaos there is no direct relation between
averages in a continuos time dynamical system (flow) and averages using the
analogous discrete system defined by the corresponding Poincare map. In
contrast to permanent chaos, results obtained from the Poincare map can even be
qualitatively incorrect. The reason is that the return time between
intersections on the Poincare surface becomes relevant. However, after
introducing a true-time Poincare map, quantities known from the usual Poincare
map, such as conditionally invariant measure and natural measure, can be
generalized to this case. Escape rates and averages, e.g. Liapunov exponents
and drifts can be determined correctly using these novel measures. Significant
differences become evident when we compare with results obtained from the usual
Poincare map.Comment: 4 pages in Revtex with 2 included postscript figures, submitted to
Phys. Rev.
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Evaluating LAB@FUTURE, a collaborative e-learning Laboratory experiments platform
This paper presents Lab@Future, an advanced e-learning platform that uses novel Information and Communication Technologies to support and expand laboratory teaching practices. For this purpose, Lab@Future uses real and computer generated objects that are interfaced using mechatronic systems, augmented reality, mobile technologies and 3D multi user environments. The main aim is to develop and demonstrate technological support for practical experiments in the following focused disciplines namely: Fluid Dynamics - Science subject in Germany, Geometry - Mathematics subject in Austria, History and Environmental Awareness – Arts and Humanities subjects in Greece and Slovenia. In order to pedagogically enhance the design and functional aspects of this e-learning technology, we are investigating the dialogical operationalisation of learning theories so as to leverage our understanding of teaching and learning practices in the targeted context of deployment. To be able to evaluate the lab@future system in its entire complexity an evaluation methodology including several phases has been developed, performing formative as well as summative evaluations
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