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1
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Treatment of the Periodically Inhomogeneous Surface: Multiple Boundary Condition

100%
Puszkarski H., Krawczyk M.
Acta Physica Polonica A
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2000
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vol. 97
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issue 6
1017-1022
EN
We deal with the following question: how can the composite nature of a boundary condition formulated for a periodically inhomogeneous surface and involving the composite surface parameter, be treated analytically? We show that when the appropriate Fourier transformation is applied, the composite boundary condition reduces to a specific eigenproblem condition, which constitutes the spectrum of eigenvalues of an "effective" surface parameter, a novel quantity we introduced to account for the nonhomogeneity of the surface.
2
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Magnonic Spectra of Ferromagnetic Composites Versus Magnetization Contrast

100%
Krawczyk M., Puszkarski H.
Acta Physica Polonica A
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1998
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vol. 93
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issue 5-6
805-810
EN
It had been shown recently that the calculated magnonic spectra of two-dimensional periodic ferromagnetic composites can present frequency ranges forbidden for the propagation of magnon excitations throughout the composite. However, those forbidden energy gaps were found to be highly sensitive to the exchange contrast between the component ferromagnetic materials but were very weakly sensitive to the contrast in spontaneous magnetizations of the two materials. Accordingly, in this paper we introduce a new mathematical definition of the exchange field acting in inhomogeneous medium. With this new definition the present theory gives magnonic spectra reasonably sensitive to magnetization contrast, as they should be from the physical viewpoint; moreover, the magnetization contrast now becomes a gap-creating factor as well.
3
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On a Combinatorial Aspect of Fashion

100%
Krawczyk M., Kułakowski K.
Acta Physica Polonica A
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2013
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vol. 123
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issue 3
560-563
EN
Simulations are performed according to the Axelrod model of culture dissemination, with modified mechanism of repulsion. Previously, repulsion was considered by Radillo-Diaz et al. as dependent on a predefined threshold. Here the probabilities of attraction and repulsion are calculated from the number of cells in the same states. We also investigate the influence of some homogeneity, introduced to the initial state. As the result of the probabilistic definition of repulsion, the ordered state vanishes. A small cluster of a few percent of population is retained only if in the initial state a set of agents is prepared in the same state. We conclude that the modelled imitation is successful only with respect to agents, and not only their features.
4
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Phononic Band Gap Width Control through Structural and Material Parameters in Two-Dimensional Phononic Crystals

100%
Śliwa I., Krawczyk M.
Acta Physica Polonica A
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2005
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vol. 108
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issue 6
943-957
EN
The phononic band structures of two-dimensional solid phononic crystals with different lattice and scatterer symmetry are studied numerically, with three types of lattice (square, triangular, and rectangular) and four different scatterer shapes (circle, hexagon, square, and rectangle) considered. XY and Z vibration modes are investigated separately. Two types of phononic crystal are considered: one composed of high-density rods embedded in a low-density matrix, the other of low-density rods in a high-density matrix. In the former case, lattice type and polarization being fixed, the broadest gaps are obtained when the symmetry of the rods corresponds to that of the lattice (the shape of a rod is identical with that of the first Brillouin zone); the largest gap width values are observed in triangular lattice-based crystals (compared to those based on the square and rectangular lattices), the shape of the corresponding first Brillouin zone being closest to a circle. These rules do not apply to structures in which the density of the rod material is lower than that of the matrix. In this case, when the symmetry of the rods corresponds to that of the lattice, gaps either fail to appear at all, or are much narrower than in other configurations. The effect of other material parameter values (such as the longitudinal and transversal velocity values) on the relation between the energy gap width and the scatterer symmetry is found to be much lesser.
5
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Ferromagnetic Layered Composites. Transfer Matrix Approach

81%
Puszkarski H., Krawczyk M., Lévy J., Mercier D.
Acta Physica Polonica A
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2001
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vol. 100
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issue Supplement
195-214
EN
A theoretical analysis of spin-wave excitations in a ferromagnetic layered composite (ABAB... ABA; A and B are different homogeneous ferromagnetic materials) is performed by means of the transfer matrix approach. We focus our attention on two features not yet well studied in the present literature, namely, the existence of forbidden energy gaps in the spin-wave mode spectrum, as well as the properties of multilayer spin-wave mode profiles. These features are discussed in relation to several multilayer characteristics, such as the filling fraction, and the exchange or magnetization contrast; surface pinning conditions and dipolar interactions are also taken into account. The existence of forbidden gaps as well as properties of mode profiles are successfully explained by having recourse to an approximate model of indepe ndent constituent sublayers. Finally, as a byproduct of our investigation, we ascertain that the conventional test for computational convergence within the finite difference method demands to be completed by symmetry mode profile verification, in addition to standard verification of the frequency convergence alone.
6
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Enhanced Photonic Band Gaps of Periodic Dielectric Structures Composed of Double Cylindrical Rods

81%
Woźniak T., Krawczyk M., Puszkarski H.
Acta Physica Polonica A
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2001
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vol. 99
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issue 5
611-625
EN
On the basis of Maradudin and McGurn's model we investigate the spectral properties of a two-dimensional photonic crystal, consisting of cylindrical rods disposed periodically throughout a dielectric matrix (the crystal is limited by two surfaces perpendicular to the axes of the rods). The model is supplemented by a new structural element in the form of dielectric rods (also cylindrical in shape) disposed coaxially within the original rods. The centers of both kinds of rods overlap forming a two-dimensional rectangular lattice in the plane parallel to the surface. Thus, the object of our study is a Maradudin-McGurn's model in which the individual rods are replaced by coaxial double rods. For this modified model we search for the optimal set of structural parameter values for which the forbidden energy gaps become greatest, giving especial attention to the role played by the additional inner rods in the emergence of gaps. We arrive at the conclusion that the condition for the opening of absolutely forbidden gaps become more favourable in a photonic crystal with double rods compared with those required in a crystal with simple rods.
7
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If Others Jump to the Queue Front, How Long I Will Wait?

81%
Krawczyk M., Gronek P., Nawojczyk M., Kułakowski K.
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EN
Two models of a queue are proposed: a human queue and two lines of vehicles before a narrowing. In both models, a queuer tries to evaluate his waiting time, taking into account the delay caused by intruders who jump to the queue front. As the collected statistics of such events is very limited, the evaluation can give very long times. The results provide an example, when direct observations should be supplemented by an inference from the context.
8
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Excitation of Bulk Spin Waves by Acoustic Wave at the Plane Defect of a Ferromagnet

81%
Gusieva Y., Graczyk P., Gorobets O., Krawczyk M.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
489-491
EN
Excitation of bulk spin waves by acoustic wave localized on the elastic planar defect in the bulk ferromagnet was analytically and numerically investigated. We showed that besides magnetic oscillations forced by acoustic wave strain the resonance between Kosevich wave and bulk spin wave can occurs. For the frequency of the Kosevich wave far below the resonance frequency the amplitude of dynamic magnetization is negligible. For the frequency above the resonance the acoustic wave excites bulk spin wave of the same frequency but different absolute value of the wave vector.
9
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Changes in serum neopterin and C-reactive protein concentrations in female dogs with mammary gland tumours

72%
Szczubiał M., Dabrowski R., Łopuszyński W., Bochniarz M., Krawczyk M., Szczubiał M., Dabrowski R., Łopuszyński W., Bochniarz M., Krawczyk M.
Polish Journal of Veterinary Sciences
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2018
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vol. 21
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issue 4
10
Content available remote

The Heaping Effect in the Survey Data on the Number of Friends

71%
Nawojczyk M., Stojkow M., Żuchowska-Skiba D., Krawczyk M., Kułakowski K.
Acta Physica Polonica A
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2018
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vol. 133
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issue 6
1417-1420
EN
The number of acquaintances is relevant for modeling social networks. Here we consider the data on the declared number of friends, as collected in 2000, 2007 and 2015 from Polish respondents above the age of 50. We demonstrate that the answers on the number of friends show sharp maxima at 10, 15, 20 and sometimes 30, which accompany a broader peak between 0 and 8. These results do not change qualitatively with sex and age of the respondents. The effect, known as data heaping, can be detected as a deviation from the Benford law.
11
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Control of the Spin Wave Phase in Transmission through the Ultrathin Interface between Exchange Coupled Ferromagnetic Materials

71%
Mailian M., Gorobets O., Gorobets Y., Zelent M., Krawczyk M.
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EN
In this paper, we show analytically and numerically, that the ultrathin metallic layer up to few monatomic layers separating two ferromagnetic media, which are exchange coupled, can effectively change the phase of the reflected or transmitted spin waves. Taking into account ground states with parallel orientations of the magnetization vectors, we developed the analytical model, which shows the possibility of spin-wave phase control by varying the exchange coupling strength between two ferromagnets. Moreover, we demonstrate with micromagnetic simulations that the effect still exists for the spin waves propagating in thin ferromagnetic film during the reflection or transmission from the interface, where interlayer exchange interactions are present.
12
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The Resonant Dynamic Magnetization Distribution in Ferromagnetic Thin Film with the Antidot

71%
Busel O., Zelent M., Gorobets O., Gorobets Y., Krawczyk M.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
492-494
EN
The influence of homogeneous dynamic microwave magnetic field applied to the permalloy (Py) thin film with a single circular antidot on the magnetization dynamics was theoretically investigated. It was considered that the Py film is saturated by the external constant magnetic field along the direction perpendicular to the film plane. The linearized Landau-Lifshitz equation was applied in order to create an analytical model of small deviations from the equilibrium values of the magnetization and magnetic field. Conditions of the local ferromagnetic resonances were defined and the dependency of resonance frequency on the magnetic field magnitude was visualized. The model has shown that the amplitude of the resonant magnetization oscillations is localized near the antidot edge and their position is dependent on the frequency.
13

The enzymatic activity of type 1 iodothyronine deiodinase (D1) is low in liver hemangioma: A preliminary study

62%
Kornasiewicz O., Debski M., Stepnowska M., Szałas A., Bar-Andziak E., Krawczyk M.
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EN
Type 1 iodothyronine deiodinase (D1) is a crucial enzyme which converts the prohormone thyroxine (T4) into active tri-iodothyronine (T3). There has been strong evidence that the metabolism of thyroid hormones is disturbed in some neoplastic tissues such as thyroid, renal, and breast cancer. However, there are few available data about D1 enzyme activity in benign tumors such as hemangioma, which is the most common primary liver tumor. Hence this study aimed to determine the enzymatic activity of D1 in hemangiomas in relation to healthy liver tissue. Seven tumors and healthy control tissues were obtained from patients who had liver resection due to hemangioma. The activity was assessed by measurement of radioactive iodine released by deiodination catalyzed by D1. It was found that D1 activity was significantly lower in the hemagiomas than in the healthy surrounding tissue (p = 0.0017). The results indicated that thyroid hormones play important roles not only in the regulation of cell metabolism, but also in cell growth, division, and apoptosis. The active form T3 acts through its nuclear receptors and influences the up- and down-regulation of target genes. Healthy liver tissue expresses a high level of D1, but disturbed D1 activity may result in changes in the local concentration of T3 which may impair gene transcription. These finding demonstrate a low enzymatic activity of D1 in liver hemangioma and suggest an as yet unknown role of thyroid hormones in this type of benign liver tumor.
14
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Naming Boys after U.S. Presidents in 20th Century

62%
Kułakowski K., Kulczycki P., Misztal K., Dydejczyk A., Gronek P., Krawczyk M.
Acta Physica Polonica A
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2016
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vol. 129
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issue 5
1038-1044
EN
This paper deals with the popularity of given names in the United States, for the period 1885-2009. Based on the data obtained from the website of U.S. Social Security Administration, it was demonstrated that the fashion of naming babies after the incumbent American president passed away in the '60s. At the same time, however, examples were given, mainly concerning celebrities, after whom babies are still named. The above theses were strengthened with the aid of quantitative data analysis by constructing an index dedicated to the specifics of the task under investigation. The obtained results were discussed in the terms of the rally effect and of the Simmel theory of fashion.
15
Content available remote

Strategies in Crowd and Crowd Structure

52%
Gawroński P., Malarz K., Krawczyk M., Malinowski J., Kupczak A., Sikora W., Kułakowski K., Wąs J., Kantelhardt J.
Acta Physica Polonica A
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2013
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vol. 123
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issue 3
522-525
EN
In an emergency situation, imitation of strategies of neighbours can lead to an order-disorder phase transition, where spatial clusters of pedestrians adopt the same strategy. We assume that there are two strategies, cooperating and competitive, which correspond to a smaller or larger desired velocity. The results of our simulations within the Social Force Model indicate that the ordered phase can be detected as an increase of spatial order of positions of the pedestrians in the crowd.
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