5,003 research outputs found
Space-Time Tradeoffs for Distributed Verification
Verifying that a network configuration satisfies a given boolean predicate is
a fundamental problem in distributed computing. Many variations of this problem
have been studied, for example, in the context of proof labeling schemes (PLS),
locally checkable proofs (LCP), and non-deterministic local decision (NLD). In
all of these contexts, verification time is assumed to be constant. Korman,
Kutten and Masuzawa [PODC 2011] presented a proof-labeling scheme for MST, with
poly-logarithmic verification time, and logarithmic memory at each vertex.
In this paper we introduce the notion of a -PLS, which allows the
verification procedure to run for super-constant time. Our work analyzes the
tradeoffs of -PLS between time, label size, message length, and computation
space. We construct a universal -PLS and prove that it uses the same amount
of total communication as a known one-round universal PLS, and factor
smaller labels. In addition, we provide a general technique to prove lower
bounds for space-time tradeoffs of -PLS. We use this technique to show an
optimal tradeoff for testing that a network is acyclic (cycle free). Our
optimal -PLS for acyclicity uses label size and computation space . We further describe a recursive space verifier for
acyclicity which does not assume previous knowledge of the run-time .Comment: Pre-proceedings version of paper presented at the 24th International
Colloquium on Structural Information and Communication Complexity (SIROCCO
2017
Dissipationless transport in low density bilayer systems
In a bilayer electronic system the layer index may be viewed as the
z-component of an isospin-1/2. An XY isospin-ordered ferromagnetic phase was
observed in quantum Hall systems and is predicted to exist at zero magnetic
field at low density. This phase is a superfluid for opposite currents in the
two layers. At B=0 the system is gapless but superfluidity is not destroyed by
weak disorder. In the quantum Hall case, weak disorder generates a random gauge
field which probably does not destroy superfluidity. Experimental signatures
include Coulomb drag and collective mode measurements.Comment: 4 pages, no figures, submitted to Phys. Rev. Let
Spin Bose Glass Phase in Bilayer Quantum Hall Systems at
We develop an effective spin theory to describe magnetic properties of the
Quantum Hall bilayer systems. In the absence of disorder this theory
gives quantitative agreement with the results of microscopic Hartree-Fock
calculations, and for finite disorder it predicts the existence of a novel spin
Bose glass phase. The Bose glass is characterized by the presence of domains of
canted antiferromagnetic phase with zero average antiferromagnetic order and
short range mean antiferromagnetic correlations. It has infinite
antiferromagnetic transverse susceptibility, finite longitudinal spin
susceptibility and specific heat linear in temperature. Transition from the
canted antiferromagnet phase to the spin Bose glass phase is characterized by a
universal value of the longitudinal spin conductance.Comment: 4 pages, 4 eps figure
Summarizing and measuring development activity
Software developers pursue a wide range of activities as part of their work, and making sense of what they did in a given time frame is far from trivial as evidenced by the large number of awareness and coordination tools that have been developed in recent years. To inform tool design for making sense of the information available about a developer's activity, we conducted an empirical study with 156 GitHub users to investigate what information they would expect in a summary of development activity, how they would measure development activity, and what factors in uence how such activity can be condensed into textual summaries or numbers. We found that unexpected events are as important as expected events in summaries of what a developer did, and that many developers do not believe in measuring development activity. Among the factors that in uence summarization and measurement of development activity, we identified development experience and programming languages.Christoph Treude, Fernando Figueira Filho, Uirá Kulesz
Studies on changes in hematological and biochemical parameters in smokeless tobacco (Gutka) chewing auto drivers in Nellore district of Andhra Pradesh, India
The present study was designed to evaluate the effect of Smokeless tobacco on some biochemical and haematological parameters. It was observed that hematological parameters of Autodrivers including hemoglobin content, white blood cell and leukocyte counts were higher in Gutka consumers than in controls, where as monocytes and basophils counts were lower. Higher biochemical parameters like serum cholesterol, glucose and protein were observed in blood samples of Gutka consumers. Decrease in serum protein levels and remarkable increase in Serum cholesterol and glucose levels were observed in Gutka consumers when compared to controls. There existed considerable difference among different hematological and biochemical parameters of gutka chewers when compared to controls
The Discovery of the Zeeman Effect in 38 GHz Class II Methanol Masers
Magnetic fields likely play an important role in star formation, but the
number of directly measured magnetic field strengths remains scarce. We
observed the 38.3 and 38.5 GHz Class II methanol (CHOH) maser lines toward
the high mass star forming region NGC 6334F for the Zeeman effect. The observed
spectral profiles have two prominent velocity features which can be further
decomposed through Gaussian component fitting. In several of these fitted
Gaussian components we find significant Zeeman detections, with
in the range from 8 to 46 Hz. If the Zeeman splitting factor for the 38 GHz
transitions is of the order of 1 Hz mG, similar to that for
several other CHOH maser lines, then magnetic fields in the regions traced
by these masers would be in the range of 8-46 mG. Such magnetic field values in
high mass star forming regions agree with those detected in the better-known
6.7 GHz Class II CHOH maser line. Since Class II CHOH masers are
radiatively pumped close to the protostar and likely occur in the accretion
disk or the interface between the disk and outflow regions, such fields likely
have significant impact on the dynamics of these disks.Comment: 10 pages, 7 figures, ApJ accepte
Pressure-tuning of the electron-phonon coupling: the insulator to metal transition in manganites
A comprehensive understanding of the physical origin of the unique magnetic
and transport properties of A_(1-x)A'^xMnO_3 manganites (A = trivalent
rare-earth and A' = divalent alkali-earth metal) is still far from being
achieved. The complexity of these systems arises from the interplay among
several competing interactions of comparable strength. Recently the
electron-phonon coupling, triggered by a Jahn-Teller distortion of the MnO_6
octahedra, has been recognised to play an essential role in the insulator to
metal transition and in the closely related colossal magneto-resistance. The
pressure tuning of the octahedral distortion gives a unique possibility to
separate the basic interactions and, at least in principle, to follow the
progressive transformation of a manganite from an intermediate towards a weak
electron-phonon coupling regime. Using a diamond anvil cell, temperature and
pressure-dependent infrared absorption spectra of La_(0.75)Ca_(0.25)MnO_3 have
been collected and, from the spectral weight analysis, the pressure dependence
of the insulator to metal transition temperature T_IM has been determined for
the first time up to 11.2 GPa. The T_IM(P) curve we proposed to model the
present data revealed a universality character in accounting for the whole
class of intermediate coupling compounds. This property can be exploited to
distinguish the intermediate from the weak coupling compounds pointing out the
fundamental differences between the two coupling regimes.Comment: 8 pages, 4 figure
Estimates of electronic interaction parameters for LaO compounds (=Ti-Ni) from ab-initio approaches
We have analyzed the ab-initio local density approximation band structure
calculations for the family of perovskite oxides, LaO with =Ti-Ni
within a parametrized nearest neighbor tight-binding model and extracted
various interaction strengths. We study the systematics in these interaction
parameters across the transition metal series and discuss the relevance of
these in a many-body description of these oxides. The results obtained here
compare well with estimates of these parameters obtained via analysis of
electron spectroscopic results in conjunction with the Anderson impurity model.
The dependence of the hopping interaction strength, t, is found to be
approximately .Comment: 18 pages; 1 tex file+9 postscript files (appeared in Phys Rev B Oct
15,1996
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