2,660 research outputs found
Vector valued Macdonald polynomials
This paper defines and investigates nonsymmetric Macdonald polynomials with
values in an irreducible module of the Hecke algebra of type . These
polynomials appear as simultaneous eigenfunctions of Cherednik operators.
Several objects and properties are analyzed, such as the canonical bilinear
form which pairs polynomials with those arising from reciprocals of the
original parameters, and the symmetrization of the Macdonald polynomials. The
main tool of the study is the Yang-Baxter graph. We show that these Macdonald
polynomials can be easily computed following this graph. We give also an
interpretation of the symmetrization and the bilinear forms applied to the
Macdonald polynomials in terms of the Yang-Baxter graph.Comment: 85 pages, 5 figure
Phase transition in the Countdown problem
Here we present a combinatorial decision problem, inspired by the celebrated
quiz show called the countdown, that involves the computation of a given target
number T from a set of k randomly chosen integers along with a set of
arithmetic operations. We find that the probability of winning the game
evidences a threshold phenomenon that can be understood in the terms of an
algorithmic phase transition as a function of the set size k. Numerical
simulations show that such probability sharply transitions from zero to one at
some critical value of the control parameter, hence separating the algorithm's
parameter space in different phases. We also find that the system is maximally
efficient close to the critical point. We then derive analytical expressions
that match the numerical results for finite size and permit us to extrapolate
the behavior in the thermodynamic limit.Comment: Submitted for publicatio
Chaos control in random Boolean networks by reducing mean damage percolation rate
Chaos control in Random Boolean networks is implemented by freezing part of
the network to drive it from chaotic to ordered phase. However, controlled
nodes are only viewed as passive blocks to prevent perturbation spread. This
paper proposes a new control method in which controlled nodes can exert an
active impact on the network. Controlled nodes and frozen values are
deliberately selected according to the information of connection and Boolean
functions. Simulation results show that the number of nodes needed to achieve
control is largely reduced compared to previous method. Theoretical analysis is
also given to estimate the least fraction of nodes needed to achieve control.Comment: 10 pages, 2 figure
Powers of the Vandermonde determinant, Schur Functions, and recursive formulas
Since every even power of the Vandermonde determinant is a symmetric
polynomial, we want to understand its decomposition in terms of the basis of
Schur functions. We investigate several combinatorial properties of the
coefficients in the decomposition. In particular, we give recursive formulas
for the coefficient of the Schur function s_{\m} in the decomposition of an
even power of the Vandermonde determinant in variables in terms of the
coefficient of the Schur function s_{\l} in the decomposition of the same
even power of the Vandermonde determinant in variables if the Young diagram
of \m is obtained from the Young diagram of \l by adding a tetris type
shape to the top or to the left. An extended abstract containing the statement
of the results presented here appeared in the Proceedings of FPSAC11Comment: 23 pages; extended abstract appeared in the Proceedings of FPSAC1
Highest weight Macdonald and Jack Polynomials
Fractional quantum Hall states of particles in the lowest Landau levels are
described by multivariate polynomials. The incompressible liquid states when
described on a sphere are fully invariant under the rotation group. Excited
quasiparticle/quasihole states are member of multiplets under the rotation
group and generically there is a nontrivial highest weight member of the
multiplet from which all states can be constructed. Some of the trial states
proposed in the literature belong to classical families of symmetric
polynomials. In this paper we study Macdonald and Jack polynomials that are
highest weight states. For Macdonald polynomials it is a (q,t)-deformation of
the raising angular momentum operator that defines the highest weight
condition. By specialization of the parameters we obtain a classification of
the highest weight Jack polynomials. Our results are valid in the case of
staircase and rectangular partition indexing the polynomials.Comment: 17 pages, published versio
Enhancing urban autonomy : towards a new political project for cities.
As the 21st Century world assumes an increasingly urban landscape, the question of how definitive urban spaces are to be governed intensifies. At the heart of this debate lies a question about the degree and type of autonomy that towns and cities might have in shaping their economic, environmental, social and cultural geography. This paper aims to examine this question. Starting with the premise that the degree of autonomy any particular town or city has is inherently an empirical question – one which can only be conceptualised in relational terms vis-à -vis the distributed, networked and territorialised responsibilities and powers of the city and the nation-state and other zones of connection – we examine four different contexts where debates over autonomy have intensified in recent history (Brazil, UK, India and South Africa). Drawing on recent respective histories, we identify key elements and enablers in the making of urban autonomy: a characteristic that exists in a variety of guises and forms and creates a patchwork landscape of differentially powerful fragments. We reveal how, beyond its characteristic as a political ideal, autonomy surfaces as a practice that emerges from within specific sectors of particular societies and through their relationship with national and regional politics. Four alternative forms of urban autonomy are delineated: fragmented, coerced (or enclave), distributed and networked. We contend that the spatial templates for autonomy are not predetermined but can be enhanced in multiple different sites and forms of political space within the city. This enhancement appears essential for the integration and strengthening of capacities for sustainable and just forms of development throughout the urban
The Partition Function of Multicomponent Log-Gases
We give an expression for the partition function of a one-dimensional log-gas
comprised of particles of (possibly) different integer charge at inverse
temperature {\beta} = 1 (restricted to the line in the presence of a
neutralizing field) in terms of the Berezin integral of an associated non-
homogeneous alternating tensor. This is the analog of the de Bruijn integral
identities [3] (for {\beta} = 1 and {\beta} = 4) ensembles extended to
multicomponent ensembles.Comment: 14 page
Algebraic invariants of five qubits
The Hilbert series of the algebra of polynomial invariants of pure states of
five qubits is obtained, and the simplest invariants are computed.Comment: 4 pages, revtex. Short discussion of quant-ph/0506073 include
Prolactin responses to stress induced by a competitive swimming effort
Purpose:The aim of the present study was to investigate the changes in prolactin (PRL) plasma concentrations induced by competitive swimming practice. Methods:Twenty-three males, 13 trained swimmers (experimental group) and 10 sedentary and healthy students (age-matched control group) took part in this investigation. The swimmers were assessed at three points: basal conditions, pre-and post-swimming competition (100 m freestyle), whereas subjects from the control group only undertook the basal trial. The variables analysed were: several body composition measures, anxiety level (STAI questionnaire), PRL and lactic acid concentrations. Results:No statistical differences were observed in PRL basal levels between groups. An evident PRL response to pre-competition psychological stress was observed in the experimental group, since the PRL plasma concentration rosefrom 4.02±0.53 ng/ml (basal conditions) to 5.52±0.53 ng/ml (p≤0.05). The PRL response to the competitive effort produced an important increase in its plasma concentration (10.07±1.59 ng/ml), showed statistical differences from pre-competition (p≤0.01) and from basal conditions (p≤0.001). A significant rise in plasma lactate levels just at the end of the effort was found, although it did not correlate with PRL levels in the same situation. Conclusion:While we observed a remarkable response of PRL to psychological and physiological stress induced by a short term competitive effort in swimming, no changes in PRL basal levels were exhibitedwith swim training. More research is needed to clarify these findings
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