Limited validity of West and Yennie integral formula for elastic scattering of hadrons

The commonly used West and Yennie integral formula for the relative phase between the Coulomb and elastic hadronic amplitudes might be consistently applied to only if the hadronic amplitude had the constant ratio of the real to the imaginary parts al all kinematically allowed values of four momentum transfer squared.Comment: 5 page

Interference between Coulomb and hadronic scattering in elastic high-energy nucleon collisions

The different models of elastic nucleon scattering amplitude will be discussed. Especially, the preference of the more general approach based on eikonal model will be summarized in comparison with the West and Yennie amplitude that played an important role in analyzing corresponding experimental data in the past.Comment: 13 pages, 2 figure

Detailed analysis of the cell-inactivation mechanism by accelerated protons and light ions

Published survival data for V79 cells irradiated by monoenergetic protons, helium-3, carbon, and oxygen ions and for CHO cells irradiated by carbon ions have been analyzed using the probabilistic two-stage model of cell inactivation. Three different classes of DNA damages formed by traversing particles have been distinguished, namely severe single-track damages which might lead to cell inactivation directly, less severe damages where cell inactivation is caused by their combinations, and damages of negligible severity that can be repaired easily. Probabilities of single ions to form these damages have been assessed in dependence on their linear energy transfer (LET) values. Damage induction probabilities increase with atomic number and LET. While combined damages play crucial role at lower LET values, single-track damages dominate in high-LET regions. The yields of single-track lethal damages for protons have been compared with the Monte Carlo estimates of complex DNA lesions, indicating that lethal events correlate well with complex DNA double-strand breaks. The decrease in the single-track damage probability for protons of LET above approx. 30 keV/$\mu$m, suggested by limited experimental evidence, is discussed, together with the consequent differences in the mechanisms of biological effects between protons and heavier ions. Applications of the results in hadrontherapy treatment planning are outlined.Comment: submitted to Physics in Medicine and Biolog

Design of solar system for family house

Cílem předkládané bakalářské práce je návrh solárního systému a jeho parametrů pro zadaný rodinný dům s ohledem na různá využití tepla přicházejícího do zařízení ve formě slunečního záření. Na základě literární studie, nabytých zkušeností a rad odborníků je v práci představena koncepce návrhu solárního systému a jeho základních částí. Samotnému návrhu solárního systému předchází seznámení se se slunečním zářením, současnými technologiemi pro jeho zpracování a jednotlivými prvky systému.Objective of this thesis is the design of solar collector and its parameters for a designated family house with regard to the different uses of heat coming into the system in the form of sunlight. Based on literature studies, experience and advice of experts is at work introduced the concept of design of the solar system and its basic parts. Introduction of the sunlight and current technologies for processing and elements of the system priors the actual design of solar system.

An investigation of diamond thin film deposition on steel substrates

The motivation behind this work was the exploration of the possibility of diamond deposition on steel substrates for low friction and low wear applications. Materials such as tungsten carbide are commercially available as diamond coated tools, where the diamond coating greatly extends the tool lifetime and performance. The diamond deposition on steel differs in terms of limitations to the diamond deposition on tungsten carbide. The main limitations of steel are its sensitivity to elevated temperatures which are commonly used for diamond deposition and a large difference in the thermal expansion coefficients of steel and diamond. Overcoming those challenging limitations would result in an introduction of competitive products for many applications. This project was a pioneering work in diamond deposition on steel substrates at Aston University in co-operation with Teer Coatings Ltd (Miba goup). The main focus was on the use of an interlayer as a facilitator of enhanced diamond growth and its adhesion towards the steel substrate. Particular attention was given to amorphous carbon coating being a buffer layer for subsequent diamond growth, followed by the investigation of diamond film growth on tungsten coated steel substrates. Interlayers were deposited using the magnetron sputtering technique at Teer Coatings. Diamond thin films were deposited at Aston University using microwave plasma chemical vapour deposition (CVD) with methane and hydrogen as a deposition gas mixture. Investigation of diamond growth from amorphous carbon films coated on steel substrates was found despite the initial promising results to provide low diamond nucleation coverage resulting samples with a sparse population of diamond crystals. The focus of the study changed into an investigation of diamond growth on steel substrates coated with metallic interlayers. As an enhancement for diamond nucleation a pre-treatment of seeding the substrates with nanocrystalline diamond particles, transferred onto the substrates by immersion into a diamond suspension, was developed and used further in this work. Tungsten coating was chosen as the main interlayer material for its diffusion barrier properties, carbide formation, specific thermal expansion coefficient and no inclination to hydrogen embrittlement. The direct tungsten deposition onto a substrate was found problematic and was initially solved by the development of a structured CrW interlayer (1 μm thick) on which an optimization of diamond CVD deposition conditions was performed. The need for a reliable temperature measurement resulted in creation of a setup with thermocouple mounted at the bottom of a substrate holder and a suitable calibration of the setup to be able to calculate the temperature of the substrate surface. CrW was found to have poor adhesion properties and a new MoW interlayer (1 μm thick) possessing excellent adhesion characteristics was developed. The diamond films deposited using previously optimised diamond deposition conditions was found to be at 785 °C. The ≈250 nm thick diamond films showed a good adhesion strength while the MoW interlayer was proved to be an effective diffusion barrier. The previously optimised diamond deposition conditions were found to deteriorate the steel substrate’s properties and further low temperature diamond deposition conditions were optimised for diamond growth at 650 °C. The resulting ≈250 nm thick films showed poor diamond adhesion characteristics due to weaker bonding between diamond and the substrate. The steel substrate did not undergo any softening during the diamond deposition. The effect of different diamond deposition temperatures, as well as the different thickness of the MoW interlayer on stress within diamond film, was studied. Lowest amount of compressive stress of 1.6 GPa was found for a sample coated with the thickest MoW (8.3 μm) and diamond deposition conditions at 650 °C. The sample showed superior adhesion upon Rockwell C indentation, while poor adhesion was observed by means of scratch testing using WC ball as an indenter

Legal and factual barriers to the termination of employment of a disabled employee in the Slovak Republic

In the first part of the article, the authors analyse the legislation of the Slovak Republic relating to the termination of employment of an employee with disabilities. In that regard, in the main part of the article, they point to the fundamental contradiction of the case-law and practice of public authorities in the question of defining a disabled employee as well as in the question of the authority of a public authority which creates fundamental practical barriers for the employer in the intended termination of employment with such an employee. The conclusion goes from practical problems to theoretical considerations of the justifiability of the legislation in question which aims to protect groups of disabled workers at particular risk