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1
Content available remote

Cyclostationarity and Resampling for Vibroacoustic Signals

100%
Leśkow J.
Acta Physica Polonica A
|
2012
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vol. 121
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issue 1A
A-160-A-163
EN
Cyclostationarity as a feature of signals was extensively studied in last decades. Publications of Serpedin or Gardner provide an important survey documenting the impact of cyclostationary models on signal analysis in telecommunication, mechanical, acoustic, and econometric signals. The aim of this paper is to introduce the concept of cyclostationarity for mechanical signals and to present the possibilities of various resampling procedures available for such signals. Recent research of Leśkow has shown applicability of bootstrap and subsampling procedures to cyclostationary models. This means, in particular, that the modern statistical mechanical signal analysis can be done without the assumption of Gaussianity and/or without specific linear filtration structure imposed on the signal. In the paper, we show that subsampling procedure proves to be a useful diagnostic tool for testing the cyclic autocorrelation structure for signals generated by vibration.
2
Content available remote

Performance of Some Robust Estimators for the Weibull Distribution

100%
Gündüz N., Başar E., Aydin C.
Acta Physica Polonica A
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2015
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vol. 128
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issue 2B
B-203-B-207
EN
In this study, we consider some of univariate quantile-based robust estimators. We focus on the estimators such as median, interquartile range, quartile and octile skewness for the Weibull distribution which is one of the most widely applied probability function because of its versatility and relative simplicity. It is important to use robust estimators as a measure of distribution properties for analyzing data in the case of contamination with outliers. For small data sets, it is reported that by introducing kernel estimation for smoothing empirical distribution function, a reduction in mean square error of estimator is achieved by Fernholz (1997) and Hubert et al. (2013). In kernel estimation, it is well known that bandwidth selection is more important than selection of kernel density since bandwidth controls the smoothness of the estimated distribution function. Using simulation studies, we examine some quantile-based estimators for the Weibull distribution with various sample size. The performance of estimators is measured by mean squared error under Different outlier contaminated data. We applied this idea in the case of real data.
3
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A Bias Reducing Approach for Some Robust Estimators by Predicting Roughness in Case of Kernel Estimation

100%
Gündüz N., Aydın C., Başar E.
Acta Physica Polonica A
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2016
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vol. 130
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issue 1
422-427
EN
In the density estimation it is known that estimators are heavily biased. We applied a bias reducing approach to improve some quantile estimators for Weibull distribution having different parameter values and contamination level. In this study, we estimate the bias for any quantile value and obtained biased reduced smoothed distribution function by simulation study for random samples of size 40. Then, the mean square error of some robust quantile estimators and variances are obtained from biased reduced smoothed distribution function. Furthermore, we obtained sampling distribution of roughness and sampling distribution of estimated bias related some quantile estimators.
4
Content available remote

Probabilistic Modeling of Delays in Data Transmission Systems with Wireless Network Interfaces Employing Random Strings Function

100%
Topór-Kamiński T., Grygiel M.
Acta Physica Polonica A
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2013
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vol. 124
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issue 3
578-581
EN
The paper presents the concepts of model construction on transmission delays in systems with wireless interfaces using random series of function. It is a new method of modelling that allows us to use probabilistic description of time required to realise tasks in various devices. It also allows us to use time domain delta function series in order to describe the time of transmission of data between transmitter and receiver. In description of delays probability density function is applied. The model also takes into account existence of intermediary network devices that play a significant role in overall budget of delay.
5
Content available remote

The Distribution of Biological Particles Suspended in Normal Cerebrospinal Fluid (CSF)

80%
Staroń W., Herbowski L.
Acta Physica Polonica A
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2010
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vol. 118
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issue 1
159-160
EN
Cerebrospinal fluid's functions are protecting, expelling and transporting which are influenced by properties of the fluid. Disorder of one of the functions may bring a disease. Cerebrospinal fluid mainly consists of water (99%), cells and proteins suspended in it. Due to the suspension it can be considered as dispersion medium. Every dispersion medium is characterized by the parameters of particles suspended in it. Parameters of dispersion medium may be classified as single or cumulative parameters. Hence, there is possible to determine additional parameters which characterize CSF in order to give full description of the fluid. The authors present results of research on suspension in normal cerebrospinal fluid worked out on the basis of 2500 microscoping pictures and they also give a statistical analysis of particle diameters. The paper is a part of research project on "Physico-chemical processes in cerebrospinal fluid obtained by puncture from patients diagnosed with the disorders of cerebrospinal fluid (CSF) circulation" realized by Institute of Physics, University of Szczecin in co-operation with Neurosurgery Ward of Public Provincial Hospital Complex in Szczecin.
6
Content available remote

Statistical Analysis of Emotions and Opinions at Digg Website

80%
Pohorecki P., Sienkiewicz J., Mitrović M., Paltoglou G., Hołyst J.
Acta Physica Polonica A
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2013
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vol. 123
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issue 3
604-615
EN
We performed statistical analysis on data from the Digg.com website, which enables its users to express their opinion on news stories by taking part in forum-like discussions as well as to directly evaluate previous posts and stories by assigning so called "diggs". Owing to fact that the content of each post has been annotated with its emotional value, apart from the strictly structural properties, the study also includes an analysis of the average emotional response of the comments about the main story. While analysing correlations at the story level, an interesting relationship between the number of diggs and the number of comments that a story received was found. The correlation between the two quantities is high for data where small threads dominate and consistently decreases for longer threads. However, while the correlation of the number of diggs and the average emotional response tends to grow for longer threads, correlations between numbers of comments and the average emotional response are almost zero. We also suggest presence of two different mechanisms governing the evolution of the discussion and, consequently, its length.
7
Content available remote

Preliminary Analysis of Size Distribution of Objects Suspended in Normal Cerebrospinal Fluid in Case of Venticular Hydrocephalic Enlargement and Internal Hydrocephalus

80%
Staroń W., Kubisz L., Herbowski L.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1A
A-46-A-48
EN
The paper presents preliminary analysis of normal non-coloured cerebrospinal fluid obtained from patients diagnosed due to suspicion of cerebrospinal fluid malabsorption. According to the findings, the normal cerebrospinal fluid was classified into two groups: A - with clinical diagnosis of ventricular hydrocephalic enlargement and B - with clinical diagnosis of internal hydrocephalus. The analysis of microscopic pictures of normal cerebrospinal fluid in both groups according to numbers and sizes of suspended objects was performed with the aid of Eclipse 600 microscope (with magnification of 1200×) working with a computer by a digital video camera. The authors observed that there is a significant difference in a shape of the distribution curve of objects' diameters between groups A and B. The maximum number of objects in group A was recorded within the range from 5 to 10 μm in diameter size whereas in group B the maximum was recorded within the range from 0.5 to 5 μm in diameter size.
8
Content available remote

Information Functionals and the Notion of (Un)Certainty: Random Matrix Theory - Inspired Case

80%
Garbaczewski P.
Acta Physica Polonica A
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2007
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vol. 112
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issue 4
619-634
EN
Information functionals allow one to quantify the degree of randomness of a given probability distribution, either absolutely (through min/max entropy principles) or relative to a prescribed reference one. Our primary aim is to analyze the "minimum information" assumption, which is a classic concept (R. Balian, 1968) in the random matrix theory. We put special emphasis on generic level (eigenvalue) spacing distributions and the degree of their randomness, or alternatively - information/organization deficit.
9
Content available remote

Emotional Analysis of Blogs and Forums Data

80%
Weroński P., Sienkiewicz J., Paltoglou G., Buckley K., Thelwall M., Hołyst J.
Acta Physica Polonica A
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2012
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vol. 121
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issue 2B
B-128-B-132
EN
We perform a statistical analysis of emotionally annotated comments in two large online datasets, examining chains of consecutive posts in the discussions. Using comparisons with randomised data we show that there is a high level of correlation for the emotional content of messages.
10
Content available remote

Dynamics of a Polish Internet-Based Social Network

80%
Zmarzłowski K., Mazur P., Orłowski A.
Acta Physica Polonica A
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2010
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vol. 117
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issue 4
700-702
EN
Dynamics of a number of new users registering for the first time to a Polish internet-base social network http://Grono.net is investigated via various regression models. Trends are estimated and the statistical significance of their forecasting is tested.
11
Content available remote

Genetic Algorithms Approach to Community Detection

80%
Mazur P., Zmarzłowski K., Orłowski A.
Acta Physica Polonica A
|
2010
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vol. 117
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issue 4
703-705
EN
The so-called community detection problem is investigated within a framework of graph theory. Genetic algorithms approach is applied to the task of identifying possible communities. Results obtained for two different fitness functions are presented and compared to each other.
12
Content available remote

The Role of Emotional Variables in the Classification and Prediction of Collective Social Dynamics

80%
Chołoniewski J., Sienkiewicz J., Hołyst J., Thelwall M.
Acta Physica Polonica A
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2015
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vol. 127
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issue 3A
A-21-A-28
EN
We demonstrate the power of data mining techniques for the analysis of collective social dynamics within British Tweets during the Olympic Games 2012. The classification accuracy of online activities related to the successes of British athletes significantly improved when emotional components of tweets were taken into account, but employing emotional variables for activity prediction decreased the classifiers' quality. The approach could be easily adopted for any prediction or classification study with a set of problem-specific variables.
13
Content available remote

Generalized Linear Models for European Union Countries Energy Data

80%
İyıt N., Yonar H., Genç A.
Acta Physica Polonica A
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2016
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vol. 130
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issue 1
397-400
EN
The class of generalized linear models is an extension of traditional linear models that allows the mean of the response variable to be linearly dependent on the explanatory variables through a link function. Generalized linear models allow the probability distribution of the response variable to be a member of an exponential family of distributions. The exponential family of distributions include many common discrete and continuous distributions such as normal, binomial, multinomial, negative binomial, Poisson, gamma, inverse Gaussian, etc. Also link functions can be built as identity, logit, probit, power, log, and complementary log-log link functions. In this study, supply, transformation and consumption, imports and exports of solid fuels, oil, gas, electricity, and renewable energy annual data of European Union countries between 2005 and 2013 years are investigated by using generalized linear models. In this case, the response variable is taken as annual complete energy balances of European Union countries as a continuous variable having positive values, and the distribution of the response variable comes from the gamma distribution with log-link function.
14
Content available remote

Comprehensive Analyses of Gaussian Graphical Model under Different Biological Networks

80%
Dokuzoğlu D., Purutçuoğlu V.
Acta Physica Polonica A
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2017
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vol. 132
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issue 3
1106-1111
EN
Naturally, genes interact with each other by forming a complicated network and the relationship between groups of genes can be shown by different functions as gene networks. Recently, there has been a growing concern in uncovering these complex structures from gene expression data by modeling them mathematically. The Gaussian graphical model is one of the very popular parametric approaches for modelling the underlying types of biochemical systems. In this study, we evaluate the performance of this probabilistic model via different criteria, from the change in dimension of the systems to the change in the distribution of the data. Hereby, we generate high dimensional simulated datasets via copulas and apply them in Gaussian graphical model to compare sensitivity, specificity, F-measure and various other accuracy measures. We also assess its performance under real datasets. We consider that such comprehensive analyses can be helpful for assessing the limitation of this common model and for developing alternative approaches, to overcome its disadvantages.
15
Content available remote

Model of Communities Isolation at Hierarchical Modular Networks

70%
Kondratiuk P., Hołyst J.
Acta Physica Polonica A
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2012
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vol. 121
|
issue 2B
B-67-B-71
EN
The model of community isolation was extended to the case when individuals are randomly placed at the nodes of hierarchical modular networks. It was shown that the average number of blocked nodes (individuals) increases in time as a power function, with the exponent depending on the network parameters. The distribution of the time when the first isolated cluster appears is unimodal, non-gaussian. The developed analytical approach is in a good agreement with the simulation data.
16
Content available remote

Granger Causality and Transfer Entropy for Financial Returns

70%
Syczewska E., Struzik Z.
Acta Physica Polonica A
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2015
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vol. 127
|
issue 3A
A-129-A-135
EN
Granger causality in its linear form has been shown by Barnett, Barrett and Seth [Phys. Rev. Lett. 103, 238701 (2009)] to be equivalent to transfer entropy in case of Gaussian distribution. Generalizations by Hlaváčková-Schindler [Appl. Math. Sci. 5, 3637 (2011)] are applied to distributions typical for biomedical applications. The financial returns, which are of great importance in financial econometrics, typically do not have Gaussian distribution. Generalizations leading to the concept of nonlinear Granger causality (e.g. causality in variance, causality in risk), known and applied in econometric literature, seem to be less known outside this field. In the paper an overview of some of the definitions and applications is given. In particular, we indicate some recent econometric results concerning application of the tests in linear multivariate framework. We emphasize importance of other variants of Granger causality, and need of development of methods reflecting features of financial variables.
17
Content available remote

Entropy Associated with Local Stabilization of the Pulse Area in Multilevel Atomic Media

70%
Alhasan A.
Acta Physica Polonica A
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2018
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vol. 133
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issue 5
1205-1214
EN
This paper provides an entropy analysis to resonant and short pulses propagation in four-level atomic medium. As an example, we take D_{1} transition in rubidium ^{87}Rb atoms including hyperfine structure. We show how to construct the time dependent Bloch-metric for each optical transition in the Liouville space. Furthermore, we attempt to relate local stabilization of the pulse area to the distribution of the space-entropy.
18
Content available remote

Toy Model for Large Non-Symmetric Random Matrices

70%
Snarska M.
Acta Physica Polonica A
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2008
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vol. 114
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issue 3
555-559
EN
Non-symmetric rectangular correlation matrices occur in many problems in economics. We test the method of extracting statistically meaningful correlations between input and output variables of large dimensionality and build a toy model for artificially included correlations in large random time series.The results are then applied to analysis of polish macroeconomic data and can be used as an alternative to classical cointegration approach.
19
Content available remote

Prediction of the Probabilities of the Transmission of Genetic Traits within Bayesian Logical Inference

61%
Cevri M., Üstündağ D.
Acta Physica Polonica A
|
2016
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vol. 130
|
issue 1
45-50
EN
Predictions for the transmission of genetic traits along to generations are an important process for patients, their family and genetic counseling. For this purpose, Bayesian analysis in which one can include a priori knowledge taking into account all relevant information into the problem could be a useful tool to examine how disease forecasting affects its probability so that it provides a more straightforward interpretation of predictions. Therefore, we investigate here transmissions of autosomal recessive diseases along to generations within Bayesian framework. In order to do that we develop a computer code that is useful to facilitate genetic transition matrices to forecast predictions of probabilities of transmission of genetic traits by using Mathematica software, well known as an algebraic manipulation language. Furthermore, the symbolic implementation of the code is applied for the cystic fibrosis disease forecasting in humans genetics. All results show that Bayesian analysis plays a central role of prediction for probabilities of transmissions of genetic traits along generations for cystic fibrosis disease or other autosomal recessive disorders.
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