66,128 research outputs found
Doob-Martin compactification of a Markov chain for growing random words sequentially
We consider a Markov chain that iteratively generates a sequence of random
finite words in such a way that the word is uniformly
distributed over the set of words of length in which letters are
and letters are : at each step an and a are shuffled in
uniformly at random among the letters of the current word. We obtain a concrete
characterization of the Doob-Martin boundary of this Markov chain. Writing
for the number of letters (equivalently, ) in the finite word
, we show that a sequence of finite words
converges to a point in the boundary if, for an arbitrary word , there is
convergence as tends to infinity of the probability that the selection of
letters and letters uniformly at random from and
maintaining their relative order results in . We exhibit a bijective
correspondence between the points in the boundary and ergodic random total
orders on the set that have distributions
which are separately invariant under finite permutations of the indices of the
s and those of the s. We establish a further bijective correspondence
between the set of such random total orders and the set of pairs of
diffuse probability measures on such that is
Lebesgue measure: the restriction of the random total order to is obtained by taking (resp. ) i.i.d. with common distribution (resp. ), letting
be in increasing
order, and declaring that the smallest element in the
restricted total order is (resp. ) if (resp. ).Comment: 24 pages, revised to deal with reviewer's comment
DFacTo: Distributed Factorization of Tensors
We present a technique for significantly speeding up Alternating Least
Squares (ALS) and Gradient Descent (GD), two widely used algorithms for tensor
factorization. By exploiting properties of the Khatri-Rao product, we show how
to efficiently address a computationally challenging sub-step of both
algorithms. Our algorithm, DFacTo, only requires two sparse matrix-vector
products and is easy to parallelize. DFacTo is not only scalable but also on
average 4 to 10 times faster than competing algorithms on a variety of
datasets. For instance, DFacTo only takes 480 seconds on 4 machines to perform
one iteration of the ALS algorithm and 1,143 seconds to perform one iteration
of the GD algorithm on a 6.5 million x 2.5 million x 1.5 million dimensional
tensor with 1.2 billion non-zero entries.Comment: Under review for NIPS 201
Impact of the recent results by the CMS and ATLAS Collaborations at the CERN Large Hadron Collider on an effective Minimal Supersymmetric extension of the Standard Model
We discuss the impact for light neutralinos in an effective Minimal
Supersymmetric extension of the Standard Model of the recent results presented
by the CMS and ATLAS Collaborations at the CERN Large Hadron Collider for a
search of supersymmetry in proton-proton collisions at a center-of-mass energy
of 7 TeV with an integrated luminosity of 35 inverse pb. We find that, in the
specific case of light neutralinos, efficiencies for the specific signature
searched by ATLAS (jets+missing transverse energy and an isolated lepton) imply
a lower sensitivity compared to CMS (which searches for jets +missing
transverse energy). Focusing on the CMS bound, if squark soft masses of the
three families are assumed to be degenerate, the combination of the ensuing
constraint on squark and gluino masses with the experimental limit on the b to
s + gamma decay imply a lower bound on the neutralino mass that can reach the
value of 11.9 GeV, depending on the gluino mass. On the other hand, when the
universality condition among squark soft parameters is relaxed, the lower bound
on the neutralino mass is not constrained by the CMS measurement and then
remains at the value 7.5 GeV derived in previous papers.Comment: 6 pages, 6 figures, typeset with ReVTeX4. A version of the paper with
full resolution figures can be found at
http://www.to.infn.it/~scopel/cms_mssm2.pd
Correct Effective Potential of Supersymmetric Yang-Mills Theory on M^4\times S^1
We study an supersymmetric Yang-Mills theory defined on
. The vacuum expectation values for adjoint scalar field in
vector multiplet, though important, has been overlooked in evaluating one-loop
effective potential of the theory. We correctly take the vacuum expectation
values into account in addition to the Wilson line phases to give an expression
for the effective potential, and gauge symmetry breaking is discussed. In
evaluating the potential, we employ the Scherk-Schwarz mechanism and introduce
bare mass for gaugino in order to break supersymmetry. We also obtain masses
for the scalars, the adjoint scalar, and the component gauge field for the
direction in case of the SU(2) gauge group. We observe that large
supersymmetry breaking gives larger mass for the scalar. This analysis is
easily applied to the case.Comment: 12 pages, 1 figur
Male Partners' Involvement Towards Prenatal Screening and Diagnostic Testing for Down Syndrome
Introduction: Now, male partners' involvement in prenatal screening and diagnostic testing for Down syndrome is becoming increasingly recognized as well to ensure that parents are well informed of the risks and benefits of screening. The aim of study was to understand the degree of male partners' involvement during pregnancy in Singapore population. Methods: A cross-sectional survey of male partners' attending prenatal counseling was performed. The instrument used to measure the level of involvement is a self-assessment questionnaire that identifies the role of male partners with a Likert scale. Descriptive statistics was used to analyze data gained. Result: A total of 107 participants completed the questionnaire. Sixty-seven percent of male partners were found to have a highlevel of involvement while 32.7% was found to have a medium level of involvement. Most of them stated that women can pursue prenatal testing without their permission. Male partners found it more important for them to accompany their spouse to amniocentesis or CVS than to the Down syndrome screening test. When participants were asked about how much information about Down syndrome they sought prior to the appointment, how much discussion they had with their spouse about Down syndrome testing, and about whether they or their spouse should be the first person to receive test results, most stated that they were undecided. Conclusion: These results revealed that male partners were very well involved in the Down syndrome testing during pregnancy and future studies should assess possible underlying factors that influence male partners' involvement
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