9,715 research outputs found
Autonomous resource-aware scheduling of large-scale media workflows
The media processing and distribution industry generally requires considerable resources to be able to execute the various tasks and workflows that constitute their business processes. The latter processes are often tied to critical constraints such as strict deadlines. A key issue herein is how to efficiently use the available computational, storage and network resources to be able to cope with the high work load. Optimizing resource usage is not only vital to scalability, but also to the level of QoS (e.g. responsiveness or prioritization) that can be provided. We designed an autonomous platform for scheduling and workflow-to-resource assignment, taking into account the different requirements and constraints. This paper presents the workflow scheduling algorithms, which consider the state and characteristics of the resources (computational, network and storage). The performance of these algorithms is presented in detail in the context of a European media processing and distribution use-case
The Radon Monitoring System in Daya Bay Reactor Neutrino Experiment
We developed a highly sensitive, reliable and portable automatic system
(H) to monitor the radon concentration of the underground experimental
halls of the Daya Bay Reactor Neutrino Experiment. H is able to measure
radon concentration with a statistical error less than 10\% in a 1-hour
measurement of dehumidified air (R.H. 5\% at 25C) with radon
concentration as low as 50 Bq/m. This is achieved by using a large radon
progeny collection chamber, semiconductor -particle detector with high
energy resolution, improved electronics and software. The integrated radon
monitoring system is highly customizable to operate in different run modes at
scheduled times and can be controlled remotely to sample radon in ambient air
or in water from the water pools where the antineutrino detectors are being
housed. The radon monitoring system has been running in the three experimental
halls of the Daya Bay Reactor Neutrino Experiment since November 2013
The Circumstellar Extinction of Planetary Nebulae
We analyze the dependence of circumstellar extinction on core mass for the
brightest planetary nebulae (PNe) in the Magellanic Clouds and M31. We show
that in all three galaxies, a statistically significant correlation exists
between the two quantities, such that high core mass objects have greater
extinction. We model this behavior, and show that the relation is a simple
consequence of the greater mass loss and faster evolution times of high mass
stars. The relation is important because it provides a natural explanation for
the invariance of the [O III] 5007 planetary nebula luminosity function (PNLF)
with population age: bright Population I PNe are extinguished below the cutoff
of the PNLF. It also explains the counter-intuitive observation that
intrinsically luminous Population I PNe often appear fainter than PNe from
older, low-mass progenitors.Comment: 12 pages, 2 figures, accepted for ApJ, April 10, 199
Optically Thick Radio Cores of Narrow-Waist Bipolar Nebulae
We report our search for optically thick radio cores in sixteen narrow-waist
bipolar nebulae. Optically thick cores are a characteristic signature of
collimated ionized winds. Eleven northern nebulae were observed with the Very
Large Array (VLA) at 1.3 cm and 0.7 cm, and five southern nebulae were observed
with the Australia Telescope Compact Array (ATCA) at 6 cm and 3.6 cm. Two
northern objects, 19W32 and M 1-91, and three southern objects, He 2-25, He
2-84 and Mz 3, were found to exhibit a compact radio core with a rising
spectrum consistent with an ionized jet. Such jets have been seen in M 2-9 and
may be responsible for shaping bipolar structure in planetary nebulae.Comment: 29 pages, accepted for publication in Ap
Studies of extreme-ultraviolet emission from Rydberg series of H_2 by electron impact
Electron excitation cross sections have been measured for the following two Rydberg series of H_2: ^1Σ_u^+ 1sσnpσ (B, B′, and B", states with principal quantum numbers n=2, 3, and 4, respectively) and ^1Π_u 1sσnpπ (C, D, and D′ states with principal quantum numbers n=2, 3, and 4, respectively) over the energy range from threshold to 350 eV. The cross sections for these six states account for all (>99%) of the vacuum-ultraviolet emission (78-170 nm) of the singlet states of H_2. The estimated total direct-excitation cross sections for these six states at 100 eV in decreasing value are (4.02±0.60)×10^(−17) cm^2 for B^1Σ_u^+ (3.86±0.60)×10^(−17) cm^2 for C^1Π_u, (0.76±0.11)×10^(−17) cm^2 for D^1Π_u, (0.76±0.11)×10^(−17) cm^2 for B' ^1Σ_u^+, (0.30±0.06)×10^(−17) cm^2 for D′^1Π_u, and (0.23±0.05)×10^(−17) cm^2 for B"^1Σ_u^+ and, additionally, (0.43±0.10)×10^(−17) cm^2 for E,F^1Σ_g^+ which populates the B^1Σ_u^+ state through radiative cascade transitions. We estimate the predissociation (autoionization is weak) and emission yields of the vibrational levels of the D, D′, and B" states whose band systems exhibit strong "breaking off in emission" for wavelengths below 85 nm. Furthermore, we report the first direct measurement of the dissociative excitation cross section for production of Lyman-β of (8.9±3.0)×10^(−19) cm^2 at 100 eV. In particular, it is shown that the high-lying Rydberg states (n=3 and 4) make a substantial contribution to the observed emission below 110 nm while above 110 nm the Lyman bands (B^1Σ_u^+→X^1Σ_g^+) and Werner bands (C^1Π_u→X^1Σ_g^+), the first members of the Rydberg series, dominate the spectrum. As a result of these measurements and spectroscopic models the ultraviolet (UV) spectrum from H_2 by electron impact can serve as an intensity calibration standard from 80 to 170 nm
Low-Temperatures Vortex Dynamics in Twinned Superconductors
We discuss the low-temperature dynamics of magnetic flux lines in samples
with a family of parallel twin planes. A current applied along the twin planes
drives flux motion in the direction transverse to the planes and acts like an
electric field applied to {\it one-dimensional} carriers in disordered
semiconductors. As in flux arrays with columnar pins, there is a regime where
the dynamics is dominated by superkink excitations that correspond to Mott
variable range hopping (VRH) of carriers. In one dimension, however, rare
events, such as large regions void of twin planes, can impede VRH and dominate
transport in samples that are sufficiently long in the direction of flux
motion. In short samples rare regions can be responsible for mesoscopic
effects.Comment: 4 pages, 2 figures email: [email protected]
Electrically tunable GHz oscillations in doped GaAs-AlAs superlattices
Tunable oscillatory modes of electric-field domains in doped semiconductor
superlattices are reported. The experimental investigations demonstrate the
realization of tunable, GHz frequencies in GaAs-AlAs superlattices covering the
temperature region from 5 to 300 K. The orgin of the tunable oscillatory modes
is determined using an analytical and a numerical modeling of the dynamics of
domain formation. Three different oscillatory modes are found. Their presence
depends on the actual shape of the drift velocity curve, the doping density,
the boundary condition, and the length of the superlattice. For most bias
regions, the self-sustained oscillations are due to the formation, motion, and
recycling of the domain boundary inside the superlattice. For some biases, the
strengths of the low and high field domain change periodically in time with the
domain boundary being pinned within a few quantum wells. The dependency of the
frequency on the coupling leads to the prediction of a new type of tunable GHz
oscillator based on semiconductor superlattices.Comment: Tex file (20 pages) and 16 postscript figure
Spinal interleukin-6 contributes to central sensitisation and persistent pain hypersensitivity in a model of juvenile idiopathic arthritis
Pain is the most debilitating symptom in juvenile idiopathic arthritis. As pain correlates poorly to the extent of joint pathology, therapies that control joint inflammation are often inadequate as analgesics. We test the hypothesis that juvenile joint inflammation leads to sensitisation of nociceptive circuits in the central nervous system, which is maintained by cytokine expression in the spinal cord. Here, transient joint inflammation was induced in postnatal day (P)21 and P40 male Sprague-Dawley rats with a single intra-articular ankle injection of complete Freund's adjuvant. Hindpaw mechanical pain sensitivity was assessed using von Frey hair and weight bearing tests. Spinal neuron activity was measured using in vivo extracellular recording and immunohistochemistry. Joint and spinal dorsal horn TNFα, IL1β and IL6 protein expression was quantified using western blotting. We observed greater mechanical hyperalgesia following joint inflammation in P21 compared to P40 rats, despite comparable duration of swelling and joint inflammatory cytokine levels. This is mirrored by spinal neuron hypersensitivity, which also outlasted the duration of active joint inflammation. The cytokine profile in the spinal cord differed at the two ages: prolonged upregulation of spinal IL6 was observed in P21, but not P40 rats. Finally, spinal application of anti-IL-6 antibody (30 ng) reduced the mechanical hyperalgesia and neuronal activation. Our results indicate that persistent upregulation of pro-inflammatory cytokines in the spinal dorsal horn is associated with neuronal sensitisation and mechanical hyperalgesia in juvenile rats, beyond the progress of joint pathology. In addition, we provide proof of concept that spinal IL6 is a key target for treating persistent pain in JIA
Study of the risk-adjusted pricing methodology model with methods of Geometrical Analysis
Families of exact solutions are found to a nonlinear modification of the
Black-Scholes equation. This risk-adjusted pricing methodology model (RAPM)
incorporates both transaction costs and the risk from a volatile portfolio.
Using the Lie group analysis we obtain the Lie algebra admitted by the RAPM
equation. It gives us the possibility to describe an optimal system of
subalgebras and correspondingly the set of invariant solutions to the model. In
this way we can describe the complete set of possible reductions of the
nonlinear RAPM model. Reductions are given in the form of different second
order ordinary differential equations. In all cases we provide solutions to
these equations in an exact or parametric form. We discuss the properties of
these reductions and the corresponding invariant solutions.Comment: larger version with exact solutions, corrected typos, 13 pages,
Symposium on Optimal Stopping in Abo/Turku 200
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