487 research outputs found
Buses of Cuernavaca - an agent-based model for universal random matrix behavior minimizing mutual information
The public transportation system of Cuernavaca, Mexico, exhibits random
matrix theory statistics [1]. In particular, the fluctuation of times between
the arrival of buses on a given bus stop, follows the Wigner surmise for the
Gaussian Unitary Ensemble. To model this, we propose an agent-based approach in
which each bus driver tries to optimize his arrival time to the next stop with
respect to an estimated arrival time of his predecessor. We choose a particular
form of the associated utility function and recover the appropriate
distribution in numerical experiments for a certain value of the only parameter
of the model. We then investigate whether this value of the parameter is
otherwise distinguished within an information theoretic approach and give
numerical evidence that indeed it is associated with a minimum of averaged
pairwise mutual information.Comment: numerical analysis extende
Statistics for Tail Processes of Markov Chains
At high levels, the asymptotic distribution of a stationary, regularly
varying Markov chain is conveniently given by its tail process. The latter
takes the form of a geometric random walk, the increment distribution depending
on the sign of the process at the current state and on the flow of time, either
forward or backward. Estimation of the tail process provides a nonparametric
approach to analyze extreme values. A duality between the distributions of the
forward and backward increments provides additional information that can be
exploited in the construction of more efficient estimators. The large-sample
distribution of such estimators is derived via empirical process theory for
cluster functionals. Their finite-sample performance is evaluated via Monte
Carlo simulations involving copula-based Markov models and solutions to
stochastic recurrence equations. The estimators are applied to stock price data
to study the absence or presence of symmetries in the succession of large gains
and losses
Hand posture recognition using modified Ensemble of Shape Functions and Global Radius-based Surface Descriptor
This paper presents an approach to recognition of static hand gestures based on data acquired from 3D cameras and point cloud descriptors: Ensemble of Shape Functions and Global Radius-based Surface Descriptor. We describe the recognition algorithm consisting of: hand segmentation, noise removal and downsampling of point cloud, dividing point cloud bounding box to cells, feature extraction and normalization, gesture classification. Modifications of the descriptors are proposed in order to increase hand posture recognition rates and decrease quantity of used features as well as computational cost of the algorithm. The experiments performed on four challenging datasets using cross-validation tests prove the usefulness of our approach
Zbawczy wymiar samotności oraz jej konsekwencje dla chrześcijanina
Solitude for Christians is not a burden but an indispensable dimension ofmaturing to sanctity. It results from the life of Christ who did not only experience loneliness in the desert and on the cross, but made it something necessary. In solitude, the cross of Christ is shown as openness to all in the realization of love. Connecting them with the solitude of Christ it is easier to bear al kindly of difficult experiences inconveniences as well as to help those who cannot cope with them
Universal shocks in the Wishart random-matrix ensemble - a sequel
We study the diffusion of complex Wishart matrices and derive a partial
differential equation governing the behavior of the associated averaged
characteristic polynomial. In the limit of large size matrices, the inverse
Cole-Hopf transform of this polynomial obeys a nonlinear partial differential
equation whose solutions exhibit shocks at the evolving edges of the eigenvalue
spectrum. In a particular scenario one of those shocks hits the origin that
plays the role of an impassable wall. To investigate the universal behavior in
the vicinity of this wall, a critical point, we derive an integral
representation for the averaged characteristic polynomial and study its
asymptotic behavior. The result is a Bessoid function.Comment: 7 pages, 2 figure
Polityka pamięci w japońsko-chińskich stosunkach dyplomatycznych
The conflict concerning historical events between Japan and China is now more visible than ever before – once again the disputes over Senkaku/ Diaoyu islands have awakened the ghosts of the past and undermined Japanese-Chinese bilateral relations. The major problems in the politics of memory between those two Asian countries are the rape of Nanking, the content of Japanese textbooks and officials’ visits in Yasukuni shrine. While the tensions are rising, Japan and China struggle to establish historical facts and present their interpretations to the society
Burgers-like equation for spontaneous breakdown of the chiral symmetry in QCD
We link the spontaneous breakdown of chiral symmetry in Euclidean QCD to the
collision of spectral shock waves in the vicinity of zero eigenvalue of Dirac
operator. The mechanism, originating from complex Burger's-like equation for
viscid, pressureless, one-dimensional flow of eigenvalues, is similar to
recently observed weak-strong coupling phase transition in large
Yang-Mills theory. The spectral viscosity is proportional to the inverse of the
size of the random matrix that replaces the Dirac operator in the universal
(ergodic) regime. We obtain the exact scaling function and critical exponents
of the chiral phase transition for the averaged characteristic polynomial for
QCD. We reinterpret our results in terms of known properties of
chiral random matrix models and lattice data.Comment: 12 page
Universal shocks in the Wishart random matrix ensemble - 1
We show that the derivative of the logarithm of the average characteristic
polynomial of a diffusing Wishart matrix obeys an exact partial differential
equation valid for an arbitrary value of N, the size of the matrix. In the
large N limit, this equation generalizes the simple Burgers equation that has
been obtained earlier for Hermitian or unitary matrices. The solution through
the method of characteristics presents singularities that we relate to the
precursors of shock formation in fluid dynamical equations. The 1/N corrections
may be viewed as viscous corrections, with the role of the viscosity being
played by the inverse of the doubled dimension of the matrix. These corrections
are studied through a scaling analysis in the vicinity of the shocks, and one
recovers in a simple way the universal Bessel oscillations (so-called hard edge
singularities) familiar in random matrix theory.Comment: 9 page
COPD in Poland – risk factor and epidemiology
Chronic obstructive pulmonary disease (COPD) falls under the category of civilization diseases. According to World Health Organization, its burden is expected to increase in the following decades, mainly due to constant exposition to the risk factors, population growth and ageing, to become the third most frequent cause of death until 2030. According to the guidelines of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) from 2015, COPD can be prevented and successfully treated. Despite the serious problem that is COPD, in many countries the data on this disease is insufficient. The most important risk factor leading to COPD that can be modified is smoking tobacco, the habit that is still popular among the adults. The knowledge of the risk factors and their elimination, as well as leading a healthy lifestyle and preference towards health behaviour that helps reducing the advancement of the disease should therefore become the basis for preventing COPD
A Sense of the Role and Value of Non-Formal Education in the Opinion of Students Participating in Interactive Workshops
The paper presents the results that relate to the opinion of the role and value of non-formal education using interactive workshops of students taking part in a series of meetings organised by the University of Rzeszow. The main method was the diagnostic survey carried out using the CAPI technique (Computer Assisted Personal Interview). Today, it is extremely important to support the traditional formal education with its other forms. As shown in the results, students expect schools to organise non-formal education, which gives them the opportunity to develop interests that stimulate learning. Based on the presented results, we can also say that activities using interactive workshops bring very satisfactory learning outcomes, so it is worth supporting and implementing similar ways of education.The paper presents the results that relate to the opinion of the role and value of non-formal education using interactive workshops of students taking part in a series of meetings organised by the University of Rzeszow. The main method was the diagnostic survey carried out using the CAPI technique (Computer Assisted Personal Interview). Today, it is extremely important to support the traditional formal education with its other forms. As shown in the results, students expect schools to organise non-formal education, which gives them the opportunity to develop interests that stimulate learning. Based on the presented results, we can also say that activities using interactive workshops bring very satisfactory learning outcomes, so it is worth supporting and implementing similar ways of education
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