3,861 research outputs found
Operating-system support for distributed multimedia
Multimedia applications place new demands upon processors, networks and operating systems. While some network designers, through ATM for example, have considered revolutionary approaches to supporting multimedia, the same cannot be said for operating systems designers. Most work is evolutionary in nature, attempting to identify additional features that can be added to existing systems to support multimedia. Here we describe the Pegasus project's attempt to build an integrated hardware and operating system environment from\ud
the ground up specifically targeted towards multimedia
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Interventions for treating pain and disability in adults with complex regional pain syndrome - An overview of systematic reviews
This article is available open access through the publisherâs website at the link below. Copyright © 2013 The Cochrane Collaboration.Background - There is currently no strong consensus regarding the optimal management of complex regional pain syndrome although a multitude of interventions have been described and are commonly used.
Objectives - To summarise the evidence from Cochrane and non-Cochrane systematic reviews of the effectiveness of any therapeutic intervention used to reduce pain, disability or both in adults with complex regional pain syndrome (CRPS).
Methods - We identified Cochrane reviews and non-Cochrane reviews through a systematic search of the following databases: Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects (DARE), Ovid MEDLINE, Ovid EMBASE, CINAHL, LILACS and PEDro. We included non-Cochrane systematic reviews where they contained evidence not covered by identified Cochrane reviews. The methodological quality of reviews was assessed using the AMSTAR tool. We extracted data for the primary outcomes pain, disability and adverse events, and the secondary outcomes of quality of life, emotional well being and participants' ratings of satisfaction or improvement. Only evidence arising from randomised controlled trials was considered. We used the GRADE system to assess the quality of evidence.
Main results - We included six Cochrane reviews and 13 non-Cochrane systematic reviews. Cochrane reviews demonstrated better methodological quality than non-Cochrane reviews. Trials were typically small and the quality variable.
There is moderate quality evidence that intravenous regional blockade with guanethidine is not effective in CRPS and that the procedure appears to be associated with the risk of significant adverse events.
There is low quality evidence that bisphosphonates, calcitonin or a daily course of intravenous ketamine may be effective for pain when compared with placebo; graded motor imagery may be effective for pain and function when compared with usual care; and that mirror therapy may be effective for pain in post-stroke CRPS compared with a 'covered mirror' control. This evidence should be interpreted with caution. There is low quality evidence that local anaesthetic sympathetic blockade is not effective. Low quality evidence suggests that physiotherapy or occupational therapy are associated with small positive effects that are unlikely to be clinically important at one year follow up when compared with a social work passive attention control.
For a wide range of other interventions, there is either no evidence or very low quality evidence available from which no conclusions should be drawn.
Authors' conclusions - There is a critical lack of high quality evidence for the effectiveness of most therapies for CRPS. Until further larger trials are undertaken, formulating an evidence-based approach to managing CRPS will remain difficult
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Time as Phase : A Dynamic Model of Time Perception
In this paper, a dynamic niodel of human time perception is presented which treats time as phase, relative to the period of an oscillator that adapts its oscillation rate in response to an input rhythm. The adaptive oscillator mechanism is characterized by four fundamental properties: (1) a preferred oscillation rate which captures the notion of a preferred tempo, (2) a fast-acting synchronisation procedure which models our ability to perceptually lock onto salient aspects of a rhythm, (3) a decay process to oppose synchroniaation, and (4) a drift process which causes the preferred rate to gradually drift towards the adapted rate, thereby modeling the context effects of long-term pattern exposure. By assuming that sensitivity to duration is a function of oscillator entrainment to the contextual rhythm, the model provides a qualitative match to data on tempo discrimination, and predicts the types of errors subjects would make on such tasks. These predictions are in agreement with data showing that subjects overestimate short intervals and underestimate long intervals
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On the Nature of Timing Mechanisms in Cognition
The ability to resolve timing differences within and between patterns is critical to the perception of music and speech; similarly, many motor skills such as music performance require fine temporal control of movements. Two important issues concern (1) the nature of the mechanism used for time measurement and (2) whether timing distinctions in perception and motor control are based on the same mechanism. In this paper, clock- and entrainment-based conceptions of time measurement are discussed; and predictions of both classes of model are then evaluated with respect to a tempo-discrimination experiment involving isochronous auditory sequences. The results from this experiment are shown to favor entrainment- over clock-based approaches to timing. The implications of these data are then discussed with respect to the hypothesized role of the cerebellum in timing
The rich-club phenomenon across complex network hierarchies
The so-called rich-club phenomenon in a complex network is characterized when
nodes of higher degree (hubs) are better connected among themselves than are
nodes with smaller degree. The presence of the rich-club phenomenon may be an
indicator of several interesting high-level network properties, such as
tolerance to hub failures. Here we investigate the existence of the rich-club
phenomenon across the hierarchical degrees of a number of real-world networks.
Our simulations reveal that the phenomenon may appear in some hierarchies but
not in others and, moreover, that it may appear and disappear as we move across
hierarchies. This reveals the interesting possibility of non-monotonic behavior
of the phenomenon; the possible implications of our findings are discussed.Comment: 4 page
Test of BPA\u27s estrogenic effects on brain aromatase expression, neural activity, and locomotive behavior in zebrafish larvae
Bisphenol A (BPA) is a well-known endocrine disrupting chemical that mimics the effects of estrogens. Aromatase B (Cyp19a1b) is a brain-specific enzyme that converts testosterone to estrogen and is highly upregulated in response to estrogen receptor activation localized to radial glial cells. During embryonic zebrafish development, there is a small window of time denoted by an increase in neurogenesis and estrogen receptor activity. Previous studies have demonstrated that a low dose BPA exposure (0.1”M) during this window causes hyperlocomotion in larval zebrafish, yet no further explanation for this behavior change has been described. The purpose of this study was to identify whether (0.1”M) BPA exposure during this developmental window could be influencing Ca2+ dynamics, and if this correlated to swim activity changes. Two transgenic zebrafish lines, Cyp19a1b:GFP and Elavl3:GCaMP, were used in order to measure changes caused by BPA exposure. Confocal microscopy imaging techniques quantified Cyp19a1b expression in radial glia and dynamic GCaMP expression in neurons over time but did not find significant effects between BPA-treated and control-treated groups for either measurement. Furthermore, swim activity tests failed to replicate the difference in time spent swimming between BPA and control groups
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