3,188 research outputs found
Quality of Experience (QoE) Assurance by a Multi-path Balanced Traffic-Splitting Algorithm in MPLS Networks
Multi-Protocol Label Switching (MPLS) technology has proven its worth for delivering new services while at the same time allowing migration from old to new generation networks. Avoidance of congestion is one of the major performance objectives of traffic engineering in MPLS networks. Load balancing can prevent the congestion caused due to inefficient allocation of network resources. Another important aspect in network performance is the end user perception of the quality delivered by the network called the Quality of Experience (QoE). The final arbiter of service performance is the end user whose opinion about quality is based on his or her perception. This end user perception of audiovisual quality is quantified by Mean opinion score (MOS). The network parameters that affect the MOS are delay, Jitter and loss.Though a number of multipath load balancing algorithms have been proposed in [1] and [2], none have proportioned traffic keeping the QoE constraint in mind. Here, a multipath load balancing algorithm is used to optimally split the incoming traffic based on the effect of average delay and jitter offered by the network so that the QoE measure of MOS is maximized. These initial results indicate that desirable QoE can be achieved by finite and small number of executions of an appropriate iterative load balancing algorithm once the step-size and the weights of the composite cost function representing combined effect of average delay and jitter are judiciously chosen
Temperature dependence of nuclear fission time in heavy-ion fusion-fission reactions
Accounting for viscous damping within Fokker-Planck equations led to various improvements in the understanding and analysis of nuclear fission of heavy nuclei.
Analytical expressions for the fission time are typically provided by Kramers' theory, which improves on the Bohr-Wheeler estimate by including the time-scale related to many-particle dissipative processes along the deformation coordinate. However, Kramers' formula breaks down for sufficiently high excitation energies where Kramers' assumption of a large barrier no longer holds. In the regime MeV, Kramers' theory should be replaced by a new theory based on the Ornstein-Uhlenbeck first-passage time method that is proposed here. The theory is applied to fission time data from fusion-fission experiments on O+Pb Th. The proposed model provides an internally consistent one-parameter fitting of fission data with a constant nuclear friction as the fitting parameter, whereas Kramers' fitting requires a value of friction which falls out of the allowed range. The theory provides also an analytical formula that in future work can be easily implemented in numerical codes such as CASCADE or JOANNE4
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Analysis of historical negative control group data from the in vitro micronucleus assay using human lymphocytes.
A database of the micronuclei counts was built up for historical negative control data from human lymphocyte in vitro micronuclei tests (MnVit) carried out in 8 laboratories with experience of the method. The mean incidence of micronucleated cells (mnt)/1000 cells ranged from 2.2/1000 to 15.9/1000. There were no large differences in incidence between the presence or absence of S9 mix or between different treatment lengths. There was also little evidence that different solvents affected the numbers of micronuclei appreciably. A number of laboratories did show significant inter-experiment variability, indicating that there remained unidentified factors affecting frequencies. Donor variance may be one such factor. Inter-individual variability may explain some of these differences. The approximate 7.5-fold difference in mnt/1000 scores in a relatively small group of experienced laboratories illustrates the potential complications that can arise if a metric like a fold increase was considered the only biologically important finding. Although there is inherent variability between experiments, it was evident that within a laboratory the overall laboratory mean remains constant over time. It is believed that these findings will provide help to laboratories conducting studies using human lymphocytes in the MnVit and to those involved in the assessment of MnVit results
Review on boiling heat transfer enhancement techniques
This is the final version. Available from MDPI via the DOI in this record. Boiling is considered an important mode of heat transfer (HT) enhancement and has several industrial cooling applications. Boiling has the potential to minimize energy losses from HT devices, compared with other convection or conduction modes of HT enhancement. The purpose of this review article was to analyze, discuss, and compare existing research on boiling heat transfer enhancement techniques from the last few decades. We sought to understand the effect of nucleation sites on plain and curved surfaces and on HT enhancement, to suggest future guidelines for researchers to consider. This would help both research and industry communities to determine the best surface structure and surface manufacturing technique for a particular fluid. We discuss pool boiling HT enhancement, and present conclusions and recommendations for future research
Phase transitions and critical behavior of black branes in canonical ensemble
We study the thermodynamics and phase structure of asymptotically flat
non-dilatonic as well as dilatonic black branes in a cavity in arbitrary
dimensions (). We consider the canonical ensemble and so the charge inside
the cavity and the temperature at the wall are fixed. We analyze the stability
of the black brane equilibrium states and derive the phase structures. For the
zero charge case we find an analog of Hawking-Page phase transition for these
black branes in arbitrary dimensions. When the charge is non-zero, we find that
below a critical value of the charge, the phase diagram has a line of
first-order phase transition in a certain range of temperatures which ends up
at a second order phase transition point (critical point) as the charge attains
the critical value. We calculate the critical exponents at that critical point.
Although our discussion is mainly concerned with the non-dilatonic branes, we
show how it easily carries over to the dilatonic branes as well.Comment: 37 pages, 6 figures, the validity of using the effective action
discussed, references adde
The Effects of Previous Misestimation of Task Duration on Estimating Future Task Duration
It is a common time management problem that people underestimate the duration of tasks, which has been termed the "planning fallacy." To overcome this, it has been suggested that people should be informed about how long they previously worked on the same task. This study, however, tests whether previous misestimation also affects the duration estimation of a novel task, even if the feedback is only self-generated. To test this, two groups of participants performed two unrelated, laboratory-based tasks in succession. Learning was manipulated by permitting only the experimental group to retrospectively estimate the duration of the first task before predicting the duration of the second task. Results showed that the experimental group underestimated the duration of the second task less than the control group, which indicates a general kind of learning from previous misestimation. The findings imply that people could be trained to carefully observe how much they misestimate task duration in order to stimulate learning. The findings are discussed in relation to the anchoring account of task duration misestimation and the memory-bias account of the planning fallacy. © 2014 Springer Science+Business Media New York
A fast algorithm for estimating transmission probabilities in QTL detection designs with dense maps
<p>Abstract</p> <p>Background</p> <p>In the case of an autosomal locus, four transmission events from the parents to progeny are possible, specified by the grand parental origin of the alleles inherited by this individual. Computing the probabilities of these transmission events is essential to perform QTL detection methods.</p> <p>Results</p> <p>A fast algorithm for the estimation of these probabilities conditional to parental phases has been developed. It is adapted to classical QTL detection designs applied to outbred populations, in particular to designs composed of half and/or full sib families. It assumes the absence of interference.</p> <p>Conclusion</p> <p>The theory is fully developed and an example is given.</p
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Pan-active imidazolopiperazine antimalarials target the Plasmodium falciparum intracellular secretory pathway.
A promising new compound class for treating human malaria is the imidazolopiperazines (IZP) class. IZP compounds KAF156 (Ganaplacide) and GNF179 are effective against Plasmodium symptomatic asexual blood-stage infections, and are able to prevent transmission and block infection in animal models. But despite the identification of resistance mechanisms in P. falciparum, the mode of action of IZPs remains unknown. To investigate, we here combine in vitro evolution and genome analysis in Saccharomyces cerevisiae with molecular, metabolomic, and chemogenomic methods in P. falciparum. Our findings reveal that IZP-resistant S. cerevisiae clones carry mutations in genes involved in Endoplasmic Reticulum (ER)-based lipid homeostasis and autophagy. In Plasmodium, IZPs inhibit protein trafficking, block the establishment of new permeation pathways, and cause ER expansion. Our data highlight a mechanism for blocking parasite development that is distinct from those of standard compounds used to treat malaria, and demonstrate the potential of IZPs for studying ER-dependent protein processing
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