Genetic algorithms for positron lifetime data

Recently, genetic algorithms have been applied for ultrafast optical spectrometry in systems with several convoluted lifetimes. We apply these algorithms and compare the results with POSFIT (by Kirkegaard and Eldrup) and LT programme (by Kansy). The analysis was applied to three types of samples: molybdenum monocrystals, Czochralski-grown silicon with oxygen precipitates, Si with under-surface cavities obtained by He + H ion co- implantation. In all three tests, the genetic algorithm performs very well, in particular for short lifetimes. Further developments to model the resolution function in genetic algorithms are needed

Correlations in interference and diffraction

Quantum formalism of Fraunhofer diffraction is obtained. The state of the diffraction optical field is connected with the state of the incident optical field by a diffraction factor. Based on this formalism, correlations of the diffraction modes are calculated with different kinds of incident optical fields. Influence of correlations of the incident modes on the diffraction pattern is analyzed and an explanation of the ''ghost'' diffraction is proposed.Comment: 16 pages, 2 figures, Latex, to appear in J. Mod. Op

Information management in DNA replication modeled by directional, stochastic chains with memory

[EN] Stochastic chains represent a key variety of phenomena in many branches of science within the context of information theory and thermodynamics. They are typically approached by a sequence of independent events or by a memoryless Markov process. Stochastic chains are of special significance to molecular biology, where genes are conveyed by linear polymers made up of molecular subunits and transferred from DNA to proteins by specialized molecular motors in the presence of errors. Here, we demonstrate that when memory is introduced, the statistics of the chain depends on the mechanism by which objects or symbols are assembled, even in the slow dynamics limit wherein friction can be neglected. To analyze these systems, we introduce a sequence-dependent partition function, investigate its properties, and compare it to the standard normalization defined by the statistical physics of ensembles. We then apply this theory to characterize the enzyme-mediated information transfer involved in DNA replication under the real, non-equilibrium conditions, reproducing measured error rates and explaining the typical 100-fold increase in fidelity that is experimentally found when proofreading and edition take place. Our model further predicts that approximately 1 kT has to be consumed to elevate fidelity in one order of magnitude. We anticipate that our results are necessary to interpret configurational order and information management in many molecular systems within biophysics, materials science, communication, and engineering. Published by AIP Publishing.It is a pleasure to thank J. M. R. Parrondo and D. G. Aleja for fruitful discussion. This work was supported the Spanish Ministry of Economy and Competitiveness (Grant Nos. MAT2013-49455-EXP and MAT2015-71806-R).Arias-Gonzalez, JR. (2016). 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Efficient analysis in planet transit surveys

With the growing number of projects dedicated to the search for extrasolar planets via transits, there is a need to develop fast, automatic, robust methods with a statistical background in order to efficiently do the analysis. We propose a modified analysis of variance (AoV) test particularly suitable for the detection of planetary transits in stellar light curves. We show how savings of labor by a factor of over 10 could be achieved by the careful organization of computations. Basing on solid analytical statistical formulation, we discuss performance of our and other methods for different signal-to-noise and number of observations.Comment: 7 pages, to be published in MNRAS, downloadable software from http://www.camk.edu.pl/~alex/#softwar

Statistics of the Microwave Background Anisotropies Caused by the Squeezed Cosmological Perturbations

It is likely that the observed large-angular-scale anisotropies in the microwave background radiation are induced by the cosmological perturbations of quantum-mechanical origin. Such perturbations are now placed in squeezed vacuum quantum states and, hence, are characterized by large variances of their amplitude. The statistical properties of the anisotropies should reflect the underlying statistics of the squeezed vacuum quantum states. The theoretical variances for the temperature angular correlation function are derived and described quantitatively. It is shown that they are indeed large. Unfortunately, these large theoretical statistical uncertainties will make the extraction of cosmological information from the measured anisotropies a much more difficult problem than we wanted it to be.Comment: 33 pages REVTEX 3.0, Direct all correspondence to L. P. Grishchuk, [email protected]

Behaviour in therapeutic medical care: evidence from general practitioners in Austria

Aim: The present study examines monetary effects of general practioners’ behaviour in therapeutic medical care to identify sample characteristics that allow differentiating between the individual general practitioner and the basic population. Subjects and methods: Medical services, provided by 3,919 general practitioners in Austria, were operationalized by means of the dependent variable “costs per patient”. Statistical outliers were identified using Chebyshev’s inequality and categorized by investigating bivariate correlations between the dependent variable and the personal characteristics of each physician. Results: Variables that relate to the size of the customer base such as number of consultations (r = 0.385) and office days (r = 0.376), correlate positively with the costs for medical services. By analyzing the portfolio of the general practitioners, we found a correlation of 0.451 between this coefficient and the costs. Statistical outliers feature an average portfolio of 44.5 different services, compared to 30.45 among non-outliers. Laboratory services especially were identified as cost drivers (r = 0.408). Statistical outliers generate at least one laboratory parameter for 44.34% of their patients, opposed to 27.2% within the rest of the sample. Consequently outliers produce higher laboratory costs than their counterparts. Conclusion: We found some evidence that physicians have influence in the provision of their services. Considering entrepreneurial objectives, the extension of the portfolio can increase their profit. Our findings indicate supplier-induced demand for several groups of services. We assume that the effect is consolidated by the fee for service system and could be compensated by adequate reform

Gravitational wave astronomy of single sources with a pulsar timing array

Abbreviated: We investigate the potential of detecting the gravitational wave from individual binary black hole systems using pulsar timing arrays (PTAs) and calculate the accuracy for determining the GW properties. This is done in a consistent analysis, which at the same time accounts for the measurement of the pulsar distances via the timing parallax. We find that, at low redshift, a PTA is able to detect the nano-Hertz GW from super massive black hole binary systems with masses of \sim10^8 - 10^{10}\,M_{\sun} less than $\sim10^5$\,years before the final merger, and those with less than $\sim10^3 - 10^4$ years before merger may allow us to detect the evolution of binaries. We derive an analytical expression to describe the accuracy of a pulsar distance measurement via timing parallax. We consider five years of bi-weekly observations at a precision of 15\,ns for close-by ($\sim 0.5 - 1$\,kpc) pulsars. Timing twenty pulsars would allow us to detect a GW source with an amplitude larger than $5\times 10^{-17}$. We calculate the corresponding GW and binary orbital parameters and their measurement precision. The accuracy of measuring the binary orbital inclination angle, the sky position, and the GW frequency are calculated as functions of the GW amplitude. We note that the "pulsar term", which is commonly regarded as noise, is essential for obtaining an accurate measurement for the GW source location. We also show that utilizing the information encoded in the GW signal passing the Earth also increases the accuracy of pulsar distance measurements. If the gravitational wave is strong enough, one can achieve sub-parsec distance measurements for nearby pulsars with distance less than $\sim 0.5 - 1$\,kpc.Comment: 16 pages, 5 figure,, accepted by MNRA