542 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
R^4 Corrections to D1D5p Black Hole Entropy from Entropy Function Formalism
We show that in IIB string theory and for D1D5p black holes in ten dimensions
the method of entropy function works. Despite the more complicated Wald formula
for the entropy of D1D5p black holes in ten dimensions, their entropy is given
by entropy function at its extremum point. We use this method for computing the
entropy of the system both at the level of supergravity and for its higher
order alpha'^3R^4 corrections.Comment: 15 pages, minor corrections, typos correcte
More on Five Dimensional EVH Black Rings
In this paper we continue our analysis of arXiv:1308.1478[hep-th] and study
in detail the parameter space of three families of doubly spinning black ring
solutions: balanced black ring, unbalanced ring and dipole-charged balanced
black rings. In all these three families the Extremal Vanishing Horizon (EVH)
ring appears in the vanishing limit of the dimensionful parameter of the
solution which measures the ring size. We study the near horizon limit of the
EVH black rings and for all three cases we find a (pinching orbifold) AdS
throat with the AdS radius where is the ring
mass and is the 5d Newton constant. We also discuss the near horizon
limit of near-EVH black rings and show that the AdS factor is replaced with
a generic BTZ black hole. We use these results to extend the EVH/CFT
correspondence for black rings, a 2d CFT dual to near-EVH black rings.Comment: 30 page
Phase transition in multi-scalar-singlet extensions of the Standard Model
We propose a generalization of the Standard Model (SM) by adding two real
gaugesinglets S1, S2. The field S1 will improve the strength of the electroweak
phase transition (EWPT). Imposing a Z2 symmetry on the field S2 makes this
field a possible candidate for dark matter. Both singlets interact with other
observable fields through Higgs boson. They are allowed to interact with each
other as well. We find that by introducing two different scalar fields, the
model is less vulnerable to experimental constraints. In this paper, we
consider the effects of a heavy scalar(M1 > MH) on the electroweak phase
transition. And we present configurations that produce a strong first order
EWPT
Handling Network Partitions and Mergers in Structured Overlay Networks
Structured overlay networks form a major class of peer-to-peer systems, which are touted for their abilities to
scale, tolerate failures, and self-manage. Any long-lived
Internet-scale distributed system is destined to face network partitions. Although the problem of network partitions
and mergers is highly related to fault-tolerance and
self-management in large-scale systems, it has hardly been
studied in the context of structured peer-to-peer systems.
These systems have mainly been studied under churn (frequent
joins/failures), which as a side effect solves the problem
of network partitions, as it is similar to massive node
failures. Yet, the crucial aspect of network mergers has been
ignored. In fact, it has been claimed that ring-based structured
overlay networks, which constitute the majority of the
structured overlays, are intrinsically ill-suited for merging
rings. In this paper, we present an algorithm for merging
multiple similar ring-based overlays when the underlying
network merges. We examine the solution in dynamic conditions,
showing how our solution is resilient to churn during
the merger, something widely believed to be difficult or
impossible. We evaluate the algorithm for various scenarios
and show that even when falsely detecting a merger, the
algorithm quickly terminates and does not clutter the network
with many messages. The algorithm is flexible as the
tradeoff between message complexity and time complexity
can be adjusted by a parameter
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