253 research outputs found
Double Chargino Production in scattering
We point out the production of the charginos and neutralinos in
electron-electron process in several supersymmetric models, in order to show
that the International Linear Collider can discover double charged charginos if
these particles really exist in nature.Comment: 9 pages, 9 figures, Talk given at CTP symposium on Supersymmetry at
LHC: Theoretical and Experimental Perspectives, The British University in
Egypt, Cairo, Egypt, 11-14 March 200
Экранное трубчатое многопараметровое вихретоковое устройство
Рассмотрено экранное трубчатое многопараметровое устройство, с помощью которого определяются четыре параметра ферромагнитной трубы: относительная магнитная проницаемость µrt, удельное электрическое сопротивление Pt, температура трубы t и коэффициент затухания магнитного поля в трубчатом изделии ht.The screen tubular mnogoparametrovoe device is considered, which four parameters of ferromagnetic pipe are determined by: relative permeance µrt, specific electric resistance Pt, temperature of pipe of t and coefficient of fading of the magnetic field in tubular good of ht
Exact Ground-State Energy of the Ising Spin Glass on Strips
We propose a new method for exact analytical calculation of the ground-state
energy of the Ising spin glass on strips. An outstanding advantage of this
method over the numerical transfer matrix technique is that the energy is
obtained for complex values of the probability describing quenched randomness.
We study the and the site-random models using this method for strips of
various sizes up to . The ground-state energy of these models is
found to have singular points in the complex-probability plane, reminiscent of
Lee-Yang zeros in the complex-field plane for the Ising ferromagnet. The Ising model has a series of singularities which may approach a limiting
point around on the real axis in the limit of infinite width.Comment: 10 pages, 12 Postscript figures, LaTeX, uses subeqn.sty, minor
changes in tex-fil
Lassoing and corraling rooted phylogenetic trees
The construction of a dendogram on a set of individuals is a key component of
a genomewide association study. However even with modern sequencing
technologies the distances on the individuals required for the construction of
such a structure may not always be reliable making it tempting to exclude them
from an analysis. This, in turn, results in an input set for dendogram
construction that consists of only partial distance information which raises
the following fundamental question. For what subset of its leaf set can we
reconstruct uniquely the dendogram from the distances that it induces on that
subset. By formalizing a dendogram in terms of an edge-weighted, rooted
phylogenetic tree on a pre-given finite set X with |X|>2 whose edge-weighting
is equidistant and a set of partial distances on X in terms of a set L of
2-subsets of X, we investigate this problem in terms of when such a tree is
lassoed, that is, uniquely determined by the elements in L. For this we
consider four different formalizations of the idea of "uniquely determining"
giving rise to four distinct types of lassos. We present characterizations for
all of them in terms of the child-edge graphs of the interior vertices of such
a tree. Our characterizations imply in particular that in case the tree in
question is binary then all four types of lasso must coincide
Recognizing Treelike k-Dissimilarities
A k-dissimilarity D on a finite set X, |X| >= k, is a map from the set of
size k subsets of X to the real numbers. Such maps naturally arise from
edge-weighted trees T with leaf-set X: Given a subset Y of X of size k, D(Y) is
defined to be the total length of the smallest subtree of T with leaf-set Y .
In case k = 2, it is well-known that 2-dissimilarities arising in this way can
be characterized by the so-called "4-point condition". However, in case k > 2
Pachter and Speyer recently posed the following question: Given an arbitrary
k-dissimilarity, how do we test whether this map comes from a tree? In this
paper, we provide an answer to this question, showing that for k >= 3 a
k-dissimilarity on a set X arises from a tree if and only if its restriction to
every 2k-element subset of X arises from some tree, and that 2k is the least
possible subset size to ensure that this is the case. As a corollary, we show
that there exists a polynomial-time algorithm to determine when a
k-dissimilarity arises from a tree. We also give a 6-point condition for
determining when a 3-dissimilarity arises from a tree, that is similar to the
aforementioned 4-point condition.Comment: 18 pages, 4 figure
Error-correcting code on a cactus: a solvable model
An exact solution to a family of parity check error-correcting codes is
provided by mapping the problem onto a Husimi cactus. The solution obtained in
the thermodynamic limit recovers the replica symmetric theory results and
provides a very good approximation to finite systems of moderate size. The
probability propagation decoding algorithm emerges naturally from the analysis.
A phase transition between decoding success and failure phases is found to
coincide with an information-theoretic upper bound. The method is employed to
compare Gallager and MN codes.Comment: 7 pages, 3 figures, with minor correction
Cluster counting: The Hoshen-Kopelman algorithm vs. spanning tree approaches
Two basic approaches to the cluster counting task in the percolation and
related models are discussed. The Hoshen-Kopelman multiple labeling technique
for cluster statistics is redescribed. Modifications for random and aperiodic
lattices are sketched as well as some parallelised versions of the algorithm
are mentioned. The graph-theoretical basis for the spanning tree approaches is
given by describing the "breadth-first search" and "depth-first search"
procedures. Examples are given for extracting the elastic and geometric
"backbone" of a percolation cluster. An implementation of the "pebble game"
algorithm using a depth-first search method is also described.Comment: LaTeX, uses ijmpc1.sty(included), 18 pages, 3 figures, submitted to
Intern. J. of Modern Physics
Extending canonical Monte Carlo methods II
Previously, we have presented a methodology to extend canonical Monte Carlo
methods inspired on a suitable extension of the canonical fluctuation relation
compatible with negative heat capacities .
Now, we improve this methodology by introducing a better treatment of finite
size effects affecting the precision of a direct determination of the
microcanonical caloric curve , as well as
a better implementation of MC schemes. We shall show that despite the
modifications considered, the extended canonical MC methods possibility an
impressive overcome of the so-called \textit{super-critical slowing down}
observed close to the region of a temperature driven first-order phase
transition. In this case, the dependence of the decorrelation time with
the system size is reduced from an exponential growth to a weak power-law
behavior , which is shown in the particular case of
the 2D seven-state Potts model where the exponent .Comment: Version submitted to JSTA
Counting, generating and sampling tree alignments
Pairwise ordered tree alignment are combinatorial objects that appear in RNA
secondary structure comparison. However, the usual representation of tree
alignments as supertrees is ambiguous, i.e. two distinct supertrees may induce
identical sets of matches between identical pairs of trees. This ambiguity is
uninformative, and detrimental to any probabilistic analysis.In this work, we
consider tree alignments up to equivalence. Our first result is a precise
asymptotic enumeration of tree alignments, obtained from a context-free grammar
by mean of basic analytic combinatorics. Our second result focuses on
alignments between two given ordered trees and . By refining our grammar
to align specific trees, we obtain a decomposition scheme for the space of
alignments, and use it to design an efficient dynamic programming algorithm for
sampling alignments under the Gibbs-Boltzmann probability distribution. This
generalizes existing tree alignment algorithms, and opens the door for a
probabilistic analysis of the space of suboptimal RNA secondary structures
alignments.Comment: ALCOB - 3rd International Conference on Algorithms for Computational
Biology - 2016, Jun 2016, Trujillo, Spain. 201
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