32 research outputs found
Possible Winners in Noisy Elections
We consider the problem of predicting winners in elections, for the case
where we are given complete knowledge about all possible candidates, all
possible voters (together with their preferences), but where it is uncertain
either which candidates exactly register for the election or which voters cast
their votes. Under reasonable assumptions, our problems reduce to counting
variants of election control problems. We either give polynomial-time
algorithms or prove #P-completeness results for counting variants of control by
adding/deleting candidates/voters for Plurality, k-Approval, Approval,
Condorcet, and Maximin voting rules. We consider both the general case, where
voters' preferences are unrestricted, and the case where voters' preferences
are single-peaked.Comment: 34 page
MOTIVATING ELEMENTARY SCHOOL LEARNERS TO ENGLISH WITH THE HELP OF SELECTED HANDBOOK CONTENT
The article explores the topic of students’ motivation and course books, that is how the content of the course books influence students’ motivation, but also how the teachers use the course books and teachers books in the classroom. The two-way research, aimed at finding answers to the main research questions, was based on the specially prepared survey conducted among teachers, but also on the (indicated by the investigated teachers as the most usable) course-book analysis. Article visualizations
Modelling and experimantal validation of fluid velocity and tracer concentration in jet reactors
The paper presents a collection of experimental data from particle image velocimetry and planar laser induced fluorescence methods containing local microstructures of fluid velocity and inert tracer concentration in jet reactors. The results of experiments, performed with resolution of the level of several microns, can be used for direct validation of CFD models, especially for timedependent mixing model used in large eddy simulations
Optical wireless communications operated at long-wave infrared radiation
This paper presents some construction analysis and test results of a Free Space Optics system operating at the wavelength of 9.35 µm. In the system, a quantum cascade laser and a photoreceiver with mercury cadmium telluride photodetectors were used. The main parameters of these elements were discussed taking into account a data link operation. It also provides to determine a data range for various weather conditions related to scattering and scintillation. The results of numerical analyses defined the properties of currently available FSO technologies working in the near infrared or in the short infrared range of spectrum versus the performances of the developed system. The operation of this system was verified in three different test environments. The obtained results may also contain important issues related to the practical application of any FSO system
Large eddy simulation of precipitation process carried out in jet reactors
The paper presents an application of large eddy simulations to predict a course of precipitation process carried out in selected types of jet reactors. In the first part of this work the simulations results were validated using PIV and PLIF techniques and also by comparing model predictions with experimental data for fast parallel chemical test reactions. In the second part of this work predictions of modeling are compared with experimental data for BaSO4 precipitation. Precipitation model is tested in this part also by comparing predictions of the model based on LES with results obtained using the multiple-time-scale mixing model combined with the k‒e model
Texture-Governed Cell Response to Severely Deformed Titanium
The phenomenon of superior biological behavior , r it observed in titanium processed by an unconventional severe plastic deformation method, that is, hydrostatic extrusion, has been described within the present study. In doing so, specimens varying significantly in the crystallographic orientation of grains, yet exhibiting comparable grain refinement, were meticulously investigated. The aim was to find the clear origin of enhanced biocompatibility of titanium-based materials, having microstructures scaled down to the submicron range. Texture, microstructure, and surface characteristics, that is, wettability, roughness, and chemical composition, were examined as well as protein adsorption tests and cell response studies were carried out. It has been concluded that, irrespective of surface properties and mean grain size, the (10 (1) over bar0) crystallographic plane favors endothelial cell attachment on the surface of the severely deformed titanium. Interestingly, an enhanced albumin, fibronectin, and serum adsorption as well as dearly directional growth of the cells with preferentially oriented cell nuclei have been observed on the surfaces having (0001) planes exposed predominantly. Overall, the biological response of titanium fabricated by severe plastic deformation techniques is derived from the synergistic effect of surface irregularities, being the effect of refined microstructures, surface chemistry, and crystallographic orientation of grains rather than grain refinement itself
Quantum Sensing for Detection of Zinc-Triggered Free Radicals in Endothelial Cells
Oxidative stress originating from the overproduction of free radicals poses a major threat to cell fate, therefore it is of great importance to address the formation of free radicals in cells subjected to various pathological stimuli. Here we investigate the free radical response of endothelial cells to biodegradable zinc. In addition to the standard free radical assays, relaxometry was used for determining the production of free radicals in cells exposed to non-physiological concentrations of zinc ions. The cellular morphology, intracellular zinc accumulation, as well as the levels of reactive oxygen/nitrogen species, are determined using standard fluorescent methods. For endothelial cells subjected to 50% zinc extracts, deviations from the normal cell shape and cell agglomeration tendency are observed. The culture medium containing the highest amount of zinc ions caused nuclei fragmentation, blebbing, and cell shrinkage, indicating cell death. A potential explanation for the observed phenomena is an overproduction of free radicals. In the case of 1% and 10% zinc extracts, the formation of free radicals is clearly confirmed by relaxometry, while the results obtained by using fluorescent techniques are unambiguous. It is revealed that high concentrations of zinc ions released from biodegradable samples induce a deleterious effect on endothelial cells.</p
Variability in Prevalence of Helicobacter pylori Strains Resistant to Clarithromycin and Levofloxacin in Southern Poland
Background. An increasing resistance of Helicobacter pylori strains to antimicrobial agents is the serious therapeutic problem. The aim of this study was to compare the primary and secondary resistance of H. pylori strains isolated between 2006–2008 (data published) and 2009–2011 to clarithromycin and levofloxacin. Material and Methods. 220 dyspeptic patients (153 before treatment, 67 after), were enrolled in the study. 51 H. pylori strains were isolated. MIC values of clarithromycin and levofloxacin were determined by the E-test method. The statistical analysis was conducted with the χ2 test with Yates correction at the 0.05 significance level (P ≤ 0.05). Results. Between 2006 and 2008, 34% (39/115) of H. pylori strains were resistant to clarithromycin (primary 21% (19/90), secondary 80% (20/25)). 5% (6/115) of strains were resistant to levofloxacin (primary 2% (2/90), secondary 16% ((4/25); data published) Between 2009–2011, 22% (11/51) of H. pylori strains were resistant to clarithromycin (primary 19% (8/43), secondary 38% (3/8)). 16% (8/51) of strains were resistant to levofloxacin (primary 12% (5/43), secondary 38% (3/8)). Conclusion. The present study has shown the increasing amount of resistant H. pylori strains isolated from patients in Southern Poland to levofloxacin and decreasing number of resistant strains to clarithromycin
Levofloxacin resistance of "Helicobacter pylori" strains isolated from patients in Southern Poland between 2006-2012
An increasing resistance of Helicobacter pylori (H. pylori) to antimicrobial agents leads to the need of regional monitoring of the prevalence resistant strains (according to the Maastricht/Florence consensus report, 2012). The aim of the study was to assess the resistance to levofloxacin of H. pylori strains isolated from adult patients of Ma≥opolska region in Poland. Bioptates taken from gastric mucosa during gastroscopy constituted the material for the study. Two hundred ten H. pylori strains were isolated from 811 patients. A majority of strains (171) came from patients before the treatment of H. pylori infections while the remaining 39 strains were isolated from patients after the failed therapy. Susceptibility of H. pylori to levofloxacin was determined by strips impregnated with antibiotic gradient (E-test, bioMerieux). The obtained minimum inhibitory concentration (MIC) values ranged from 0.002 mg/L to 32 mg/L. The percentage of strains resistant to levofloxacin amounted to 8.10% (17/210). Among the group of strains isolated from patients before the treatment, 5.85% (10/171) of H. pylori strains were resistant to levofloxacin. In the group of strains isolated from patients after the treatment 17.95% (7/39) of strains were resistant. The difference in the frequency of H. pylori strains resistant to levofloxacin in patients before and after the treatment of the infection due to H. pylori was statistically significant (p = 0.0297). The low percentage of H. pylori strains resistant to levofloxacin justify that the introduction of a triple therapy with levofloxacin is a good alternative in the treatment of H. pylori infections, especially in regions with high prevalence of H. pylori strains resistant to clarithromycin (> 20%)