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result(s) for
"Pokorny, Ma"
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Scintillation Characteristics of the Single-Crystalline Film and Composite Film-Crystal Scintillators Based on the Cesup.3+-Doped sub.5Osub.12 Mixed Garnets under Alpha and Beta Particles, and Gamma Ray Excitations
2022
The crystals of (Lu,Gd)[sub.3](Ga,Al)[sub.5]O[sub.12] multicomponent garnets with high density ρ and effective atomic number Z[sub.eff] are characterized by high scintillation efficiency and a light yield value up to 50,000 ph/MeV. During recent years, single-crystalline films and composite film/crystal scintillators were developed on the basis of these multicomponent garnets. These film/crystal composites are potentially applicable for particle identification by pulse shape discrimination due to the fact that α-particles excite only the film response, γ-radiation excites only the substrate response, and β-particles excite both to some extent. Here, we present new results regarding scintillating properties of selected (Lu,Gd)[sub.3](Ga,Al)[sub.5]O[sub.12]:Ce single-crystalline films under excitation by alpha and beta particles and gamma ray photons. We conclude that some of studied compositions are indeed suitable for testing in the proposed application, most notably Lu[sub.1.5]Gd[sub.1.5]Al[sub.3]Ga[sub.2]O[sub.12]:Ce film on the GAGG:Ce substrate, exhibiting an α-particle-excited light yield of 1790-2720 ph/MeV and significantly different decay curves excited by α- and γ-radiation.
Journal Article
Case report: atypical fungal obstruction of the left ventricular assist device outflow cannula
2014
We describe a very rare case of outflow cannula obstruction with fungal infectious thrombus formation. Discussion includes the etiology, diagnosis, and management of fungal infection complications related with long-term mechanical circulatory support. Left ventricular assist devices (LVADs) are increasingly used as bridge to transplant and permanent long-term therapy in the population with end-stage heart failure. Even though better clinical outcomes have been achieved with the newer-generation continuous-flow devices, infection complications are still a major risk for patients with continuous-flow LVAD implantation in long-term follow-up [Ann Thorac Surg 90:1270-1277, 2010]. Device-related infections can be categorized as driveline infections, pump-pocket infections, and LVAD-associated endocarditis [Expert Rev Med Devices 8: 627-634, 2011]. The microbiological profile is very heterogeneous; the most common pathogens are Staphylococcus, Pseudomonas, Streptococcus species, and Candida. Severe fungal infection may lead to dysfunction of the LVAD due to obstructive mass formation within the device. Due to the only anecdotal reports in the current literature, we present a very rare case of outflow fungal infectious thrombus formation leading to outflow cannula obstruction in patient with LVAD.
Journal Article
Prototype Design and Experimental Evaluation of Autonomous Collaborative Communication System for Emerging Maritime Use Cases
2021
Automated systems have been seamlessly integrated into several industries as part of their industrial automation processes. Employing automated systems, such as autonomous vehicles, allows industries to increase productivity, benefit from a wide range of technologies and capabilities, and improve workplace safety. So far, most of the existing systems consider utilizing one type of autonomous vehicle. In this work, we propose a collaboration of different types of unmanned vehicles in maritime offshore scenarios. Providing high capacity, extended coverage, and better quality of services, autonomous collaborative systems can enable emerging maritime use cases, such as remote monitoring and navigation assistance. Motivated by these potential benefits, we propose the deployment of an Unmanned Surface Vehicle (USV) and an Unmanned Aerial Vehicle (UAV) in an autonomous collaborative communication system. Specifically, we design high-speed, directional communication links between a terrestrial control station and the two unmanned vehicles. Using measurement and simulation results, we evaluate the performance of the designed links in different communication scenarios and we show the benefits of employing multiple autonomous vehicles in the proposed communication system.
Journal Article
Nest boxes increase reproductive output for Tree Swallows in a forest grassland matrix in central British Columbia
by
Norris, Andrea R.
,
Pokorny, Stanley
,
Martin, Kathy
in
Analysis
,
Animal behavior
,
Animal reproduction
2018
Secondary cavity-nesting birds depend on tree cavities for nesting and roosting, but many studies of these birds are conducted using nest boxes. Implementation of effective conservation strategies for cavity-nesting species such as nest-site supplementation requires careful comparisons of fecundity and other vital rates for birds using both natural and artificial nest site types. We compared breeding phenology, clutch and brood sizes, and fledging success of Tree Swallows (Tachycineta bicolor) nesting in tree cavities and nest boxes during 2001-2003 in British Columbia, Canada. Swallows using nest boxes initiated egg-laying and hatched young at approximately the same time as those in tree cavities (2 June, 23 June, respectively). Female Tree Swallows in boxes laid larger clutches (5.9 ± 0.9 eggs, N = 76) than those in tree cavities (4.2 ± 1.6 eggs, N = 67). The mean number of nestlings hatched was greater in nest boxes (5.2 ± 1.1 nestlings, N = 67) than in tree cavities (2.6 ± 2.0 nestlings, N = 58). Pairs in boxes were over twice as successful in producing fledglings (93.4%; 57 of 61 pairs fledged > 1 young) than those in tree cavities (35.8%; 19 of 53 pairs). Of those successful nests, pairs nesting in boxes fledged 5.1 ± 1.1 young (N = 57), whereas those in tree cavities fledged 3.5 ± 1.2 young (N = 18). Because cavities in nest boxes averaged 60% larger in volume and 1.8 cm wider internally than tree cavities, we suggest that increased reproductive output was correlated with boxes enabling a larger clutch size. In previous research, we found that Tree Swallows were a poor competitor with other cavity-nesting passerines for tree cavities. The addition of nest boxes may serve as an effective way to supplement local reproduction for secondary cavity-nesting bird populations by reducing competition for limited nest sites. This is especially true in regions where the availability of natural nesting sites is highly variable, and where species compete with many other cavity-nesting passerines using a similar ecological niche and nesting cavities.
Journal Article
Prognostic Utility of Biomarkers in Predicting of One-Year Outcomes in Patients with Aortic Stenosis Treated with Transcatheter or Surgical Aortic Valve Implantation
2012
The aim of the work was to find biomarkers identifying patients at high risk of adverse clinical outcomes after TAVI and SAVR in addition to currently used predictive model (EuroSCORE).
There is limited data about the role of biomarkers in predicting prognosis, especially when TAVI is available.
The multi-biomarker sub-study included 42 consecutive high-risk patients (average age 82.0 years; logistic EuroSCORE 21.0%) allocated to TAVI transfemoral and transapical using the Edwards-Sapien valve (n = 29), or SAVR with the Edwards Perimount bioprosthesis (n = 13). Standardized endpoints were prospectively followed during the 12-month follow-up.
The clinical outcomes after both TAVI and SAVR were comparable. Malondialdehyde served as the best predictor of a combined endpoint at 1 year with AUC (ROC analysis) = 0.872 for TAVI group, resp. 0.765 (p<0.05) for both TAVI and SAVR groups. Increased levels of MDA, matrix metalloproteinase 2, tissue inhibitor of metalloproteinase (TIMP1), ferritin-reducing ability of plasma, homocysteine, cysteine and 8-hydroxy-2-deoxyguanosine were all predictors of the occurrence of combined safety endpoints at 30 days (AUC 0.750-0.948; p<0.05 for all). The addition of MDA to a currently used clinical model (EuroSCORE) significantly improved prediction of a combined safety endpoint at 30 days and a combined endpoint (0-365 days) by the net reclassification improvement (NRI) and the integrated discrimination improvement (IDI) (p<0.05). Cystatin C, glutathione, cysteinylglycine, asymmetric dimethylarginine, nitrite/nitrate and MMP9 did not prove to be significant. Total of 14.3% died during 1-year follow-up.
We identified malondialdehyde, a marker of oxidative stress, as the most promising predictor of adverse outcomes during the 30-day and 1-year follow-up in high-risk patients with symptomatic, severe aortic stenosis treated with TAVI. The development of a clinical \"TAVIscore\" would be highly appreciated. Such dedicated scoring system would enable further testing of adjunctive value of various biomarkers.
Journal Article
Structural Study of Metakaolin-Phosphate Geopolymers Prepared with Wide Range of Al/P Molar Ratios
2025
Geopolymers represent an innovative and environmentally sustainable alternative to traditional construction materials, offering significant potential for reducing anthropogenic CO2 emissions. Among these, phosphoric acid-activated metakaolin-based systems have attracted increasing attention for their chemical and thermal resilience. In this study, we present a comprehensive structural and mechanical evaluation of metakaolin-based geopolymers synthesized across a wide range of Al/P molar ratios (0.8–4.0). Six formulations were systematically prepared and analyzed using X-ray powder diffraction (XRPD), small-angle X-ray scattering (SAXS), Fourier-transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (ssNMR), and complementary mechanical testing. The novelty of this work lies in the integrated mapping of composition–structure–property relationships across the broad Al/P spectrum under controlled synthesis, combined with the rare application of SAXS to reveal composition-dependent nanoscale domains (~18–50 nm). We identify a stoichiometric window at Al/P ≈ 1.5, where complete acid consumption leads to a structurally homogeneous AlVI–O–P network, yielding the highest compressive strength. In contrast, acid-rich systems exhibit divergent flexural and compressive behaviors, with enhanced flexural strength linked to hydrated silica domains arising from metakaolin dealumination, quantitatively tracked by 29Si MAS NMR. XRPD further reveals the formation of uncommon Si–P crystalline phases (SiP2O7, Si5P6O25) under low-temperature curing in acid-rich compositions. Together, these findings provide new insights into the nanoscale structuring, phase evolution, and stoichiometric control of silica–alumino–phosphate geopolymers, highlighting strategies for optimizing their performance in demanding thermal and chemical environments.
Journal Article
Study of the variability of scapular inclination and the glenoid version - considerations for preoperative planning: clinical-radiological study
2017
Background
Preoperative planning with the aid of imaging methods is a principal factor in successful surgery on the shoulder. This work aims to evaluate the variability of glenoid version, spiralling twist and scapular inclination in relation to the frontal axis. Studies focusing on measuring the variability of scapular inclination in the standardised rest position are lacking in the literature.
Methods
We evaluated 104 CT scans of the shoulder. We measured the glenoid version with respect to the scapular axis at three levels. We measured the scapular inclination angle in relation to the sagittal plane and we determined scapular inclination in relation to the frontal axis. Statistical evaluation was performed using the marginal linear model and parameters were estimated using the generalised least squares method, which enables the dependency of measurements performed on the same subject to be taken into consideration.
Results
The highest values of retroversion are attained by the glenoid in the cranial section (average -9.96°, range -29.7 to +13.2°). Proof of the spiralling twist is the decline in retroversion at the centre of the glenoid (average -2.09°, range -16.7 to +11.6°).
Retroversion decreases further in the inferior direction (average -0.5°, range -20.9 to +17.5°). The average thoracoscapular angle is 45.46°, ranging from 13.1 to 69.0°. The average scapular inclination in relation to the frontal plane is 44.54°, ranging from 21.0 to76.9°.
Conclusions
During preoperative planning, the surgeon should take into consideration not only the glenoid version in relation to the scapular axis, but also the value of the scapular inclination so as to eliminate possible surgical errors, optimise prosthesis implantation and thus decrease the risk of functional restrictions of the joint.
Clinical trial registration
Ethics Committee for Multi-Centric Clinical Trials (EK-554/14,29thApril 2014).
Journal Article
Testing the Production Potential of Paulownia Clon In Vitro 112(R) in the Czech Republic
2023
Paulownia is a deciduous fast-growing tree with intensive sprouting ability and is well adapted to various climatic and soil conditions. Its native area extends from the middle to the lower section of the Yangtze River. The aim of our research was to test the potential of Paulownia Clon in vitro 112(R) for production of saw timber in the conditions of the Czech Republic. In 2016, three private plantations were established-Střelice, Vlčatín and Vorel. The parameters that were measured were the total height, the height of the live above-ground part of each plant after the winter, the stem thickness at 10 cm above the ground, and the stem thickness at breast height. The measurements were taken from 2016 to 2021. At all plantations, the plants achieved very small mean annual increments in height (under 1 m) and thickness (under 1 cm). On average, 39% of the upper above-ground part of each plant was damaged by frost each winter and the cumulative mortality was 28% to 53%.
Journal Article
Possibilities of Using the Duplex System Plasma Nitriding + CrN Coating for Special Components
by
Studeny, Zbynek
,
Joska, Zdenek
,
Kolomy, Stepan
in
Ballistics
,
Chemical vapor deposition
,
Chromium plating
2022
The article deals with the replacement of hard chrome plating by applying the duplex system plasma nitriding + CrN coating (hereinafter referred to as PN + CrN). The goal of the research was to find a suitable alternative for steel surface treatment that would replace hard chrome plating and ensure similar mechanical and tribological properties. An exposed part of a small-bore weapon was selected for evaluation, namely the gas piston of the 42CrMo4 steel breech mechanism drive. The PN + CrN duplex system was compared with a hard chrome coating as well as a self-deposited CrN coating. The mentioned surface treatments were evaluated in terms of metallography, mechanical and tribological properties and surface texture. From the mechanical properties, the hardness of the surface was analyzed, an indentation test was performed (Mercedes test) and adhesive-cohesive behavior was evaluated (Scratch test). Furthermore, an instrumented penetration test was performed (an evaluation of plastic and elastic deformation work and indentation hardness). As part of the assessment of tribological properties, the Ball-on-Flat test, the measurement of the coefficient of friction and the measurement of traces of wear were performed. The surface texture was evaluated in terms of morphology and surface roughness measurement by selected 2D and 3D parameters. The PN + CrN duplex system showed higher hardness than hard chrome, better tribological properties (lower friction coefficient), but worse surface texture. The PN + CrN duplex system has proven to be a suitable alternative to the hard chrome coating for exposed parts of small-caliber weapons, which can be applied in arms production.
Journal Article
Equivalent Keys: Side-Channel Countermeasure for Post-Quantum Multivariate Quadratic Signatures
2022
Algorithms based on the hardness of solving multivariate quadratic equations present promising candidates for post-quantum digital signatures. Contemporary threats to implementations of cryptographic algorithms, especially in embedded systems, include side-channel analysis, where attacks such as differential power analysis allow for the extraction of secret keys from the device’s power consumption or its electromagnetic emission. To prevent these attacks, various countermeasures must be implemented. In this paper, we propose a novel side-channel countermeasure for multivariate quadratic digital signatures through the concept of equivalent private keys. We propose a random equivalent key to be generated prior to every signing, thus randomizing the computation and mitigating side-channel attacks. We demonstrate our approach on the Rainbow digital signature, but since an unbalanced oil and vinegar is its special case, our work is applicable to other multivariate quadratic signature schemes as well. We analyze the proposed countermeasure regarding its properties such as the number of different equivalent keys or the amount of required fresh randomness, and we propose an efficient way to implement the countermeasure. We evaluate its performance regarding side-channel leakage and time/memory requirements. Using test vector leakage assessment, we were not able to detect any statistically significant leakage from our protected implementation.
Journal Article