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Search Results: 1 - 10 of 118135 matches for " Bartosz T. Grobelny "
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Complement Inhibition as a Proposed Neuroprotective Strategy following Cardiac Arrest
Brad E. Zacharia,Zachary L. Hickman,Bartosz T. Grobelny,Peter A. DeRosa,Andrew F. Ducruet,E. Sander Connolly
Mediators of Inflammation , 2009, DOI: 10.1155/2009/124384
Abstract: Out-of-hospital cardiac arrest (OHCA) is a devastating disease process with neurological injury accounting for a disproportionate amount of the morbidity and mortality following return of spontaneous circulation. A dearth of effective treatment strategies exists for global cerebral ischemia-reperfusion (GCI/R) injury following successful resuscitation from OHCA. Emerging preclinical as well as recent human clinical evidence suggests that activation of the complement cascade plays a critical role in the pathogenesis of GCI/R injury following OHCA. In addition, it is well established that complement inhibition improves outcome in both global and focal models of brain ischemia. Due to the profound impact of GCI/R injury following OHCA, and the relative lack of effective neuroprotective strategies for this pathologic process, complement inhibition provides an exciting opportunity to augment existing treatments to improve patient outcomes. To this end, this paper will explore the pathophysiology of complement-mediated GCI/R injury following OHCA.
An Estimation of the Capital Growth Rate in Business Activities  [PDF]
Bartosz Kurek
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.34047
Abstract: The aim of the paper is to empirically assess whether capital growth rates (defined as in the paper) realized by companies constituting Standard & Poor’s indices: S&P 600, S&P 400 and S&P 500 were higher in years prior to crisis, i.e. in years: 2007, 2006, 2005 than the average growth rates in preceding 5-year periods, i.e. in periods: 2002-2006, 2001-2005 and 2000-2004. A statistical test concerning the differences between means was used as a research method. In order to achieve that 9 hypotheses were tested in total. The further purpose of this paper is to estimate capital growth rates for every index in each of the years from 2000 up to 2007, as well as in 5- and 8-year periods. In total 40 confidence intervals for capital growth rates were constructed in order to achieve that goal. M. Dobija’s theory of capital was used as a background for a research. According to that theory capital is an abstract ability to perform labor. Homogeneous capital is embodied in heterogeneous assets. Capital is subdued to a number of laws: 1) the conservation principle and 2) the dispersion principle. These laws form the fundamentals of the theory of capital. The concentration of capital in any particular time moment is described in the form of the equation, where initial capital is influenced by the three factors: a natural potential of growth, a spontaneous diffusion and an inflow of capital by human labor and management. The natural potential of growth may be estimated by a properly defined ROA index. Realized ROA by a single company in a particular time period is a random number. However, in a large sample of companies, the average ROA index over a long time period concentrates around the natural potential for growth. The research shows that in most cases the capital growth rates were statistically higher in years prior to crisis than the average growth rates in preceding 5-year periods. Similarly—in most cases—the average rate of return on assets in each of the indices was increasing from year to year in nominal terms. That increased return on assets might strengthen the believes of investors that higher and higher profits are achievable on a regular basis. However, it seems that investors did not acknowledge that returns will float towards the average ultimately as the theory of capital describes.
The role of colour preattentive processing in human-computer interaction task efficiency: a preliminary study
Rafal Michalski,Jerzy Grobelny
Computer Science , 2012, DOI: 10.1016/j.ergon.2007.11.002
Abstract: In this paper, results of experimental research on the preattentive mechanism in the human-computer interaction (HCI) were presented. Fifty four subjects were asked to find interface elements from various panel structures. The arrangements were differentiated by their orientation (vertical, horizontal), colour pattern (ordered, unordered) and object background colours (green-blue, green-red, blue-red). The main finding of the study generally confirms the profits provided by the visual preattentive processing of the colour feature in graphical panel operation efficiency. However, the vertical way of arranging the items in search layouts resulted in decreasing the preattentive effect related to the item background colour. In regular, chessboard-like patterns of different coloured items, the effect of the early vision was less salient than in the case of structures with randomly dispersed colours. The reported results can help in designing efficient graphical user-computer interfaces in many interactive information systems.
Various approaches to a human preference analysis in a digital signage display design
Jerzy Grobelny,Rafal Michalski
Computer Science , 2012, DOI: 10.1002/hfm.20295
Abstract: The paper is concerned with various ways of analysing the subjective assessment of displaying digital signage content. In the beginning the brief description of the signage system evolution is described and next, the carried out ex-periment is depicted. The preferences of the 32 subjects were obtained using pairwise comparisons of the designed screen formats. Then the priorities were derived by applying the Analytic Hierarchy Process (Saaty, 1977; 1980) framework. The gathered data were modelled and analysed by means of the analysis of variance, multiple regression, conjoint and factor analysis. The results suggest that the application of different methods of preference analysis may provide additional information, which could facilitate more in-depth understanding of the given preference structure.
Dimension and cut vertices: an application of Ramsey theory
William T. Trotter,Bartosz Walczak,Ruidong Wang
Computer Science , 2015,
Abstract: Motivated by quite recent research involving the relationship between the dimension of a poset and graph theoretic properties of its cover graph, we show that for every $d\geq 1$, if $P$ is a poset and the dimension of a subposet $B$ of $P$ is at most $d$ whenever the cover graph of $B$ is a block of the cover graph of $P$, then the dimension of $P$ is at most $d+2$. We also construct examples which show that this inequality is best possible. We consider the proof of the upper bound to be fairly elegant and relatively compact. However, we know of no simple proof for the lower bound, and our argument requires a powerful tool known as the Product Ramsey Theorem. As a consequence, our constructions involve posets of enormous size.
A Series Approach to Perturbed Stochastic Volterra Equations of Convolution Type  [PDF]
Anna Karczewska, Bartosz Bandrowski
Advances in Pure Mathematics (APM) , 2015, DOI: 10.4236/apm.2015.511060
Abstract: In the paper, perturbed stochastic Volterra Equations with noise terms driven by series of independent scalar Wiener processes are considered. In the study, the resolvent approach to the equations under consideration is used. Sufficient conditions for the existence of strong solution to the class of perturbed stochastic Volterra Equations of convolution type are given. Regularity of stochastic convolution is supplied, as well.
On the Beer index of convexity and its variants
Martin Balko,t Jelínek,Pavel Valtr,Bartosz Walczak
Mathematics , 2014,
Abstract: Let $S$ be a subset of $\mathbb{R}^d$ with finite positive Lebesgue measure. The Beer index of convexity $\operatorname{b}(S)$ of $S$ is the probability that two points of $S$ chosen uniformly independently at random see each other in $S$. The convexity ratio $\operatorname{c}(S)$ of $S$ is the Lebesgue measure of the largest convex subset of $S$ divided by the Lebesgue measure of $S$. We investigate the relationship between these two natural measures of convexity of $S$. We show that every set $S\subseteq\mathbb{R}^2$ with simply connected components satisfies $\operatorname{b}(S)\leq\alpha\operatorname{c}(S)$ for an absolute constant $\alpha$, provided $\operatorname{b}(S)$ is defined. This implies an affirmative answer to the conjecture of Cabello et al. asserting that this estimate holds for simple polygons. We also consider higher-order generalizations of $\operatorname{b}(S)$. For $1\leq k\leq d$, the $k$-index of convexity $\operatorname{b}_k(S)$ of $S\subseteq\mathbb{R}^d$ is the probability that the convex hull of a $(k+1)$-tuple of points chosen uniformly independently at random from $S$ is contained in $S$. We show that for every $d\geq 2$ there is a constant $\beta(d)>0$ such that every set $S\subseteq\mathbb{R}^d$ satisfies $\operatorname{b}_d(S)\leq\beta\operatorname{c}(S)$, provided $\operatorname{b}_d(S)$ exists. We provide an almost matching lower bound by showing that there is a constant $\gamma(d)>0$ such that for every $\varepsilon\in(0,1]$ there is a set $S\subseteq\mathbb{R}^d$ of Lebesgue measure one satisfying $\operatorname{c}(S)\leq\varepsilon$ and $\operatorname{b}_d(S)\geq\gamma\frac{\varepsilon}{\log_2{1/\varepsilon}}\geq\gamma\frac{\operatorname{c}(S)}{\log_2{1/\operatorname{c}(S)}}$.
Job satisfaction and gender identity of women managers and non-managers
Agnieszka Lipińska-Grobelny, Katarzyna Wasiak
International Journal of Occupational Medicine and Environmental Health , 2010, DOI: 10.2478/v10001-010-0015-6
Abstract: Objectives: This work investigates different cognitive aspects of job satisfaction (co-workers, supervisor, job content, working facilities, organization and management, opportunities for development, income), positive and negative affect at work and their relations to gender role orientation of women occupying managerial and non-managerial positions. Materials and methods: The sample of 122 women (60 managers and 62 non-managers) completed a battery of instruments such as: the Bem Sex Role Inventory, the Job Description Inventory by Neuberger and Allerbeck and the Job Affect Scale by Brief et al. Results: Most women managers represented androgynous and masculine types, while women non-managers belonged to androgynous and feminine types. Moreover, women with various degrees of sex-typing showed positive and negative affect at work. The most satisfied with income were masculine women managers, the least — feminine women non-managers. Conclusions: These results may be applied in designing of motivational instruments to enhance job effectiveness and to eliminate unproductive behaviours such as absenteeism, high staff turnover.
Ray tracing method in a 3D analysis of fiber-optic elements
J.S. Witkowski,A. Grobelny
Optica Applicata , 2008,
Abstract: In this paper, a numerical analysis of algorithm of optical fiber systems with dimensions much larger than light wavelength has been presented. This algorithm can be used especially in the case of multimode fiber-optic elements. The presented technique of the analysis is based on the ray tracing method (RTM). Up to now, the RTM was widely used for an analysis of lens-systems. In this paper, a new possibility for this method in fiber optic elements analysis has been shown. The algorithm permits to determine thousands of ray traces simultaneously in a desired 3D area of an arbitrarily defined refractive index. This technique can be applied for a gradient index (GI), step index (SI) fibers, different types of optical couplers, etc. The algorithm has been extended to analyze dispersion properties and pulse shape evolution tracking along a fiber-optic system.
The effects of graphical interface design characteristics on human-computer interaction task efficiency
Rafal Michalski,Jerzy Grobelny,Waldemar Karwowski
Computer Science , 2012, DOI: 10.1016/j.ergon.2006.06.013
Abstract: The main objective of this paper was to investigate the effects of a computer screen interface design and its related geometrical characteristics of 36 graphical objects on a user's task efficiency. A total of 490 subjects took part in laboratory experiments that focused on the direct manipulation of a visual dialogue between a user and a computer. The subjects were asked to select an object from among a group of items randomly placed on the computer screen that were visible exclusively during the visual search process. A model expressing the mean object acquisition time as a function of graphical object size and the configuration was developed and statistically validated. The model showed an influence of geometrical design characteristics of the graphical objects (icons) and their groupings (icon structures) on the observed task efficiency. The reported results can be used at those stages of a software lifecycle that concentrate on prototyping, designing, and implementing graphical solutions for the efficient graphical user-computer interface.
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