362 research outputs found
Exploiting the Synergy Between Gossiping and Structured Overlays
In this position paper we argue for exploiting the synergy between gossip-based algorithms and structured overlay networks (SON). These two strands of research have both aimed at building fault-tolerant, dynamic, self-managing, and large-scale distributed systems. Despite the common goals, the two areas have, however, been relatively isolated. We focus on three problem domains where there is an untapped potential of using gossiping combined with SONs. We argue for applying gossip-based membership for ring-based SONs---such as Chord and Bamboo---to make them handle partition mergers and loopy networks. We argue that small world SONs---such as Accordion and Mercury---are specifically well-suited for gossip-based membership management. The benefits would be better graph-theoretic properties. Finally, we argue that gossip-based algorithms could use the overlay constructed by SONs. For example, many unreliable broadcast algorithms for SONs could be augmented with anti-entropy protocols. Similarly, gossip-based aggregation could be used in SONs for network size estimation and load-balancing purposes
A first-order spatial integer-valued autoregressive SINAR(1,1) model.
Binomial thinning operator has a major role in modeling one-dimensional integer-valued autoregressive time series models. The purpose of this article is to extend the use of such operator to define a new stationary first-order spatial non negative, integer-valued autoregressive SINAR (1,1) model. We study some properties of this model like the mean, variance and autocorrelation function. Yule-Walker estimator of the model parameters is also obtained. Some numerical results of the model are presented and, moreover, this model is applied to a real data set
Possibility of primordial black holes as the source of gravitational wave events in the advanced LIGO detector
The analysis of gravitational Wave (GW) data from advanced LIGO provides the
mass of each companion of binary black holes as the source of GWs. The mass of
events corresponding to the binary black holes from GW is above M
which is much larger than the mass of astrophysical black holes detected by
x-ray observations. In this work, we examine primordial black holes (PBHs) as
the source of LIGO events. Assuming that of the dark matter is made of
PBHs, we estimate the rate at which these objects make binaries, merge, and
produce GWs as a function of redshift. The gravitational lensing of GWs by PBHs
can also enhance the amplitude of the strain. We simulate GWs sourced by binary
PBHs, with the detection threshold of for both Livingston and Hanford
detectors. For the log-normal mass function of PBHs, we generate the expected
distribution of events, compare our results with the observed events, and find
the best value of the mass function parameters (i.e., and
) in the log-normal mass function. Comparing the expected number of
events with the number of observed ones rules out the present-Universe binary
formation PBH scenario as the candidate for the source of GW events detected by
LIGO.Comment: Final published versio
Gravity on Noncommutative D-Branes
The effective action for the low energy scattering of two gravitons with a
D-brane in the presence of a constant antisytmetric field in bosonic string
theory is calculated and the modification to the standard D-brane action to
first order in is obtained.Comment: 18 pages, Latex file, accepted in Int. J. Mod. Phys.
Cross country relations in European tourist arrivals
This paper introduces an optimized Multivariate Singular Spectrum Analysis (MSS) algorithm for identifying leading indicators. Exploiting European tourist arrivals data, we analyse cross country relations for European tourism demand. Cross country relations have the potential to aid in planning and resource allocations for future tourism demand by taking into consideration the variation in tourist arrivals across other countries in Europe. Our findings indicate with statistically significant evidence that there exists cross country relations between European tourist arrivals which can help in improving the predictive accuracy of tourism demand. We also find that MSSA has the capability of not only identifying leading indicators, but also forecasting tourism demand with far better accuracy in comparison to its univariate counterpart, Singular Spectrum Analysis
On Isolated Conformal Fixed Points and Noncritical String Theory
We search for the gravity description of unidentified field theories at their
conformal fixed points by studying the low energy effective action of six
dimensional noncritical string theory. We find constant dilaton solutions by
solving both the equations of motion and BPS equations. Our solutions include a
free parameter provided by a stack of uncharged space filling branes. We find
several AdS_p\times S^q solutions with constant radii for AdS_p and S^q. The
curvature of the solutions are of the order of the string scale.Comment: 17 pages, Latex fil
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