1,222 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
Mechanisms for the Increased Fatigability of the Lower Limb in People with Type 2 Diabetes
Fatiguing exercise is the basis of exercise training and a cornerstone of management of type 2 diabetes mellitus (T2D), however, little is known about the fatigability of limb muscles and the involved mechanisms in people with T2D. The purpose was to compare fatigability of knee extensor muscles between people with T2D and controls without diabetes and determine the neural and muscular mechanisms for a dynamic fatiguing task. Seventeen people with T2D (10 men, 7 women: 59.6{plus minus}9.0 years) and 21 age-, BMI- and physical activity-matched controls (11 men, 10 women: 59.5{plus minus}9.6 years) performed 120 high-velocity concentric contractions (1 contraction/3 s) with a load equivalent to 20% maximal voluntary isometric contraction (MVIC) torque with the knee extensors. Transcranial magnetic stimulation (TMS) and electrical stimulation of the quadriceps were used to assess voluntary activation and contractile properties. People with T2D had larger reductions than controls in power during the fatiguing task (39.9{plus minus}20.2% vs. 28.3{plus minus}16.7%, P2=0.364, P=0.002). Although neural mechanisms contributed to fatigability, contractile mechanisms were responsible for the greater knee extensor fatigability in men and women with T2D compared with healthy controls
A review of stochastic resonance: Circuits and measurement
Copyright © 2002 IEEENoise in dynamical systems is usually considered a nuisance. However, in certain nonlinear systems, including electronic circuits and biological sensory systems, the presence of noise can enhance the detection of weak signals. The phenomenon is termed stochastic resonance and is of great interest for electronic instrumentation. We review and investigate the stochastic resonance of several bistable circuits. A new type of S characteristic circuit is demonstrated using simple nonlinear elements with an operational amplifier. Using this circuit, the effects on stochastic resonance were determined as the slope of the S shaped characteristic curve was varied.Gregory P. Harmer, Bruce R. Davis and Derek Abbot
Boundary condition at the junction
The quantum graph plays the role of a solvable model for a two-dimensional
network. Here fitting parameters of the quantum graph for modelling the
junction is discussed, using previous results of the second author.Comment: Replaces unpublished draft on related researc
"Illusion of control" in Minority and Parrondo Games
Human beings like to believe they are in control of their destiny. This
ubiquitous trait seems to increase motivation and persistence, and is probably
evolutionarily adaptive. But how good really is our ability to control? How
successful is our track record in these areas? There is little understanding of
when and under what circumstances we may over-estimate or even lose our ability
to control and optimize outcomes, especially when they are the result of
aggregations of individual optimization processes. Here, we demonstrate
analytically using the theory of Markov Chains and by numerical simulations in
two classes of games, the Minority game and the Parrondo Games, that agents who
optimize their strategy based on past information actually perform worse than
non-optimizing agents. In other words, low-entropy (more informative)
strategies under-perform high-entropy (or random) strategies. This provides a
precise definition of the "illusion of control" in set-ups a priori defined to
emphasize the importance of optimization.Comment: 17 pages, four figures, 1 tabl
A Preliminary Discussion of the Kinematics of BHB and RR Lyrae Stars near the North Galactic Pole
The radial velocity dispersion of 67 RR Lyrae variable and blue horizontal
branch (BHB) stars that are more than 4 kpc above the galactic plane at the
North Galactic Pole is 110 km/sec and shows no trend with Z (the height above
the galactic plane). Nine stars with Z < 4 kpc show a smaller velocity
dispersion (40 +/-9 km/sec) as is to be expected if they mostly belong to a
population with a flatter distribution. Both RR Lyrae stars and BHB stars show
evidence of stream motion; the most significant is in fields RR2 and RR3 where
24 stars in the range 4.0 < Z < 11.0 kpc have a mean radial velocity of -59 +/-
16 km/sec. Three halo stars in field RR 2 appear to be part of a moving group
with a common radial velocity of -90 km/sec. The streaming phenomenon therefore
occurs over a range of spatial scales. The BHB and RR Lyrae stars in our sample
both have a similar range of metallicity (-1.2 < [Fe/H] < -2.2). Proper motions
of BHB stars in fields SA 57 (NGP) and the Anticenter field (RR 7) (both of
which lie close to the meridional plane of the Galaxy) show that the stars that
have Z 4 kpc have a Galactic V motion that is
< -200 km/sec and which is characteristic of the halo. Thus the stars that have
a flatter distribution are really halo stars and not members of the metal-weak
thick-disk.Comment: Accepted for publication in the March 1996 AJ. 15 pages, AASTeX V4.0
latex format (including figures), 2 eps figures, 2 separate AASTeX V4.0 latex
table
Quantum field theory on quantum graphs and application to their conductance
We construct a bosonic quantum field on a general quantum graph. Consistency
of the construction leads to the calculation of the total scattering matrix of
the graph. This matrix is equivalent to the one already proposed using
generalized star product approach. We give several examples and show how they
generalize some of the scattering matrices computed in the mathematical or
condensed matter physics litterature.
Then, we apply the construction for the calculation of the conductance of
graphs, within a small distance approximation. The consistency of the
approximation is proved by direct comparison with the exact calculation for the
`tadpole' graph.Comment: 32 pages; misprints in tree graph corrected; proofs of consistency
and unitarity adde
Evaluation of low density array technology for quantitative parallel measurement of multiple genes in human tissue
BACKGROUND: Low density arrays (LDAs) have recently been introduced as a novel approach to gene expression profiling. Based on real time quantitative RT-PCR (QRT-PCR), these arrays enable a more focused and sensitive approach to the study of gene expression than gene chips, while offering higher throughput than more established approaches to QRT-PCR. We have now evaluated LDAs as a means of determining the expression of multiple genes simultaneously in human tissues and cells. RESULTS: Comparisons between LDAs reveal low variability, with correlation coefficients close to 1. By performing 2-fold and 10-fold serial dilutions of cDNA samples in the LDAs we determined a clear linear relationship between the gene expression data points over 5 orders of magnitude. We also showed that it is possible to use LDAs to accurately and quantitatively detect 2-fold changes in target copy number as well as measuring genes that are expressed with low and high copy numbers in the range of 1 × 10(2 )– 1 × 10(6 )copies. Furthermore, the data generated by the LDA from a cell based pharmacological study were comparable to data generated by conventional QRT-PCR. CONCLUSION: LDAs represent a valuable new approach for sensitive and quantitative gene expression profiling
Bosonization and Scale Invariance on Quantum Wires
We develop a systematic approach to bosonization and vertex algebras on
quantum wires of the form of star graphs. The related bosonic fields propagate
freely in the bulk of the graph, but interact at its vertex. Our framework
covers all possible interactions preserving unitarity. Special attention is
devoted to the scale invariant interactions, which determine the critical
properties of the system. Using the associated scattering matrices, we give a
complete classification of the critical points on a star graph with any number
of edges. Critical points where the system is not invariant under wire
permutations are discovered. By means of an appropriate vertex algebra we
perform the bosonization of fermions and solve the massless Thirring model. In
this context we derive an explicit expression for the conductance and
investigate its behavior at the critical points. A simple relation between the
conductance and the Casimir energy density is pointed out.Comment: LaTex 31+1 pages, 2 figures. Section 3.6 and two references added. To
appear in J. Phys. A: Mathematical and Theoretica
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