Simple model of bouncing ball dynamics: displacement of the table assumed as quadratic function of time

Nonlinear dynamics of a bouncing ball moving in gravitational field and colliding with a moving limiter is considered. Displacement of the limiter is a quadratic function of time. Several dynamical modes, such as fixed points, 2 - cycles and chaotic bands are studied analytically and numerically. It is shown that chaotic bands appear due to homoclinic structures created from unstable 2 - cycles in a corner-type bifurcation.Comment: 11 pages, 6 figure

Simple model of bouncing ball dynamics. Displacement of the limiter assumed as a cubic function of time

Nonlinear dynamics of a bouncing ball moving vertically in a gravitational field and colliding with a moving limiter is considered and the Poincare map, describing evolution from an impact to the next impact, is described. Displacement of the limiter is assumed as periodic, cubic function of time. Due to simplicity of this function analytical computations are possible. Several dynamical modes, such as fixed points, 2 - cycles and chaotic bands are studied analytically and numerically. It is shown that chaotic bands are created from fixed points after first period doubling in a corner-type bifurcation. Equation for the time of the next impact is solved exactly for the case of two subsequent impacts occurring in the same period of limiter's motion making analysis of chattering possible.Comment: 8 pages, 1 figure, presented at the DSTA 2011 conference, Lodz, Polan

Konflikty w organizacjach wielokulturowych – wyniki badań pilotażowych

Globalizacja istotnie wpływa na rozwój organizacji wielokulturowych na całym świecie. Zjawisko to dotyczy również firm w Polsce, bowiem coraz większa liczba przedsiębiorstw decyduje się na zatrudnienie pracowników z różnych narodowości. Różnice kulturowe pomiędzy pracownikami mogą negatywnie wpływać na wydajność zespołu, zadowolenie z pracy i klimat organizacyjny, a także prowadzić do konfliktów na tle kulturowym. Konflikty kulturowe mogą prowadzić do przemocy i napięć między grupami, a także do dyskryminacji i braku zrozumienia. Niniejszy artykuł ma na celu zdiagnozowanie częstotliwości występowania konfliktów na tle kulturowym oraz sposobów ich rozwiązywania i zapobiegania w polskich organizacjach

Mitochondrial genotype in vulvar carcinoma - cuckoo in the nest

Vulvar squamous cell carcinoma (VSCC) is a rare female genital neoplasm. Although numerous molecular changes have been reported in VSCC, biomarkers of clinical relevance are still lacking. On the other hand, there is emerging evidence on the use of mtDNA as a diagnostic tool in oncology. In order to investigate mtDNA status in VSCC patients, haplogroup distribution analysis and D-loop sequencing were performed. The results were compared with available data for the general Polish population, cancer free-centenarians as well as patients with endometrial and head and neck cancer. The obtained data were also compared with the current status of mitochondrial databases. Significant differences in haplogroup distribution between VSCC cohort, general Polish population and cancer-free centenarians cohort were found. Moreover, a correlation between the VSCC patients haplogroup and HPV status was observed. Finally, a specific pattern of mtDNA polymorphisms was found in VSCC. Our results suggest that the mitochondrial genetic background may influence the risk of VSCC occurrence as well as susceptibility to HPV infection

A quick approach for rheological evaluation of warm asphalt binders using response surface method

This paper describes a quick approach for quantification of the effects of a chemical warm named Rediset, and its interactions with temperature and aging on the rheological properties of asphalt binders using Response Sur-face Method. The central composite method was applied to design experimental programs for three test temperature conditions, namely; very high temperature (120–180 °C), high temperature (46–82 °C), and intermediate temperature (19–31 °C). Rotational viscosity, G*/sin δ and G*sin δ were selected as parameters to assess the effects of the chemical warm additive on the rheological properties of asphalt binders for different aging conditions. Evaluation of the effects of this additive on the transformed value of G*/sin δ at high temperatures indicates that additive content has significant effect on Ln(G*/sin δ). The results for intermediate temperatures show that this additive has a positive effect on G*sin δ of asphalt binders

Identifying future research priorities in the field of interpersonal violence (IV) towards athletes in sport: A Delphi study

Objective. Our aim was to define the priorities for future research in safeguarding athletes from interpersonal violence (IV) in sport through a Delphi consensus study of researchers in the field. Methods. An internet-based three-round Delphi method was used as a multi-stage facilitation technique to arrive at group consensus (set at ≥75% agreement). A targeted literature search was conducted to develop a list of potential research priorities that were presented as short statements in the first round. Results. A total of 52 participants (researchers in IV in sport) took part in the first round, 52 completed the second round, and 44 completed the third round. Respectively, 47 items, 83 items and 60 items were included in each round. The participants achieved consensus on 11 statements in the first round, 7 in the second round, and 31 in the third round, for a total of 49 consensus research priorities. The first four priorities that reached consensus (78.8% to 80.8% agreement) directly following the first Delphi round were scored with high importance (between 6.2 and 6.3 on a scale of 7). Those four priorities included: 1) documenting the experiences of children athletes and minors, 2) studying the disclosure or reporting of violence, 3) developing, evaluating, and advising on interventions targeting education and training, and 4) documenting the experiences of violence of para athletes. Conclusion. This study defines research priorities for IV in sport that may elucidate further gaps in current policies and practices

Response of optical hydrogen lines to beam heating: I. Electron beams

We investigate the role of non-thermal electrons in the formation regions of Halpha, Hbeta, and Hgamma lines in order to unfold their influence on the formation of these lines. We concentrate on pulse-beam heating varying on a subsecond timescale. Furthermore, we theoretically explore possibility that a new diagnostic tool exists indicating the presence of non-thermal electrons in the flaring chromosphere based on observations of optical hydrogen lines. To model the evolution of the flaring atmosphere and the time-dependent hydrogen excitation and ionisation, we used a 1-D radiative hydrodynamic code combined with a test-particle code that simulates the propagation, scattering, and thermalisation of a power-law electron beam in order to obtain the flare heating and the non-thermal collisional rates due to the interaction of the beam with the hydrogen atoms. All calculated models have shown a time-correlated response of the modelled Balmer line intensities on a subsecond timescale, with a subsecond timelag behind the beam flux. Depending on the beam parameters, both line centres and wings can show pronounced intensity variations. The non-thermal collisional rates generally result in an increased emission from a secondary region formed in the chromosphere.Comment: 13 pages, 11 figures, accepted to Astronomy and Astrophysic