Bitcoin transactions are recorded in a public ledger known as the blockchain. Critical to its security is the distributed system that maintains the blockchain, which is run by individuals known as miners. Bitcoin has a total market capitalization of 273bn US Dollars as of September 2022, and one bitcoin is exchanged at 19,000 US Dollars in the market. Despite its vast market capitalization growth and popularity since its inception, the scalability and efficiency of Bitcoin are still puzzling questions for researchers. This paper used the daily time series data from the inception until September 7, 2022, to analyze the relationship between bitcoin miners' competition and the Bitcoin blockchain's efficiency. The number of daily transactions and average block validation time were used as indicators for the system's efficiency, and the Herfindahl-Hirschman Index (HHI) of miners' hash rate is used as a proxy for mining concentration. Controlling for necessary factors, the econometric analysis in this paper shows that concentration in bitcoin mining is associated with lower system efficiency. Higher competition between miners leads to a higher number of Bitcoin transactions and a lower block validation time.

<p> A procedure was established for instrumental radioactivation analysis of selenium in biological materials using se77m, and used to determine selenium bound to plasma and cells of blood from 254 normal individuals. Variations with time, age, sex and hematocrit were investigated. Analysis of subfractions of plasma and cells indicated the highest selenium concentration in the plasma alpha and beta globulins. The selenium content of other tissues was determined for two individuals.</p> <p> A method was devised for instrumental radioactivation analysis of sulphur in dialyzed biological material using s37. The bound sulphur content of samples of plasma and cells from normal human blood was determined. The method would appear to have application in the instrumental activation analysis for other elements in various matrices.</p> / Thesis / Doctor of Philosophy (PhD)

This is Part A of the Thesis. Here is the Link to Part B: http://hdl.handle.net/11375/17845 / <p> This study was focused on the absorption spectra of tin dioxide thin films on optical quartz substrates. The films were doped with antimony from zero to ten percent, indium from zero to ten percent, and intrinsically, by heating undoped samples in vacuum and air. The surface resistances were also measured.</p> <p> The results for antimony doping show that the energy required for electron transitions from valence to conduction bands, the associated phonon energies, and the optical absorption by free carriers all increase while resistance decreases with increased doping. These results are consistant with antimony acting as a donor in SnO2 and elevating the Fermi level, which is in the conduction band for the undoped material, to a higher level, thus increasing the free carrier concentration. The results possibly also indicate a strain on the lattice caused by doping.</p> <p> The results for indium doping show a similar increase in energies along with a decrease in optical absorption by free carriers and an increase in resistance with increased doping. The indium acts as an acceptor and, in so doing, causes the Fermi level to drop into the valence band, at the doping levels used in this study. This is probably due to the formation of an acceptor band above or overlapping the valence band and resulting in a reduction of the free carrier concentration. The increase in phonon energy indicates that the doping imposes a strain on the lattice.</p> </p> Heating undoped films in vacuum appears to drive off oxygen resulting in reduced resistance and therefore higher free carrier concentration due to lattice defect doping, and reduced valence to conduction band transition energy possibly due to the formation of a conduction band in the forbidden band-gap. The changes were reversible by re-heating in air.</p> / Thesis / Master of Engineering (MEngr)

This is Part B of the Thesis. Here is the Link to Part A: http://hdl.handle.net/11375/17844 / <p> This report deals with the effects of various parameters on the resistance and the temperature coefficient of resistance (or the T.C.) of tin dioxide films doped with antimony and boron. The films were produced on cylindrical ceramic substrates by the hydrolysis of SnCl4 and SbCls in the presence of HCl and H3BO3. The T.C. was measured over the range of 25 to 150°C and averaged.</p> <p> Under normal conditions, the films were produced at 950°C with an antimony concentration of 0.457 molar % and a boron concentration of 2.73 molar %. Varying this firing temperature (from 800-1100°C) was found to have no effect on the resistance but increased the T.C. by 2 to 3 ppm/°C per degree change. Varying the antimony content from 0 to about 1 molar % was found to have little effect on resistance. The effect on T.C. was to increase it at lower Sb levels and then to decrease the T.C. as the level increased.</p> <p> Varying the boron content (0 to 4.46 molar %) was also found to have little effect on resistance. A decrease in T.C. with boron content was noted when only the boron was varied, but an increase in T.C. was found when HCl and H2O volumes were varied with the boron. The introduction of additional air into the system was found to have no effect.</p> <p> Film thicknesses were varied by controlling the chemical flowrates. Thinner films were found to have dramatically higher resistances and reduced T.C. values. It was observed that below a certain flowrate resistive failure occurred in the films. It was found in this study that within the statistical distribution of film values, those samples with above average resistance had below average T.C. values and vice-versa. Annealing in vacuum at 500°C was found to produce samples of reduced resistance and increased T.C. while the opposite was found with air annealed samples. Quickly cooled samples were found to be more stable.</p> / Thesis / Master of Engineering (MEngr)

<p> The time relationship of metabolically important trace metals (Fe, Cu, Zn, Co, Cd, Cr) in Lake Erie plankton were analyzed from samples collected during an algal (Aphanizomenon) bloom. Iron and cobalt showed a rapid increase in concentretion during the initial period of the bloom, followed by a decrease and levelling off to an equilibrium value. Copper and zinc were found to behave similarily undergoing a slight decrease at the beginning and then steadily increasing in concentration with time. Different depths of sampling were correlated to the life-death cycle of the organism and specific metal concentration trends. Algae from the lowest level of sampling (9.7 m; dead organism level) exhibited an increasing nutrient concentration (Fe, Zn, Co, and PO4) with time.</p> <p> Factor analysis suggested a Fe, Co, depth, 1/Biomass relationship; a Cu, Zn relationship; and a PO4, time relationship. The first two were verified from the experimental results; the last was not.</p> / Thesis / Bachelor of Science (BSc)

This is Part A of the Thesis. The link to Part B is here: / <p> A radioactive technique to determine interfacial area between solid-liquid and liquid-liquid phases has been investigated. Plastic and liquid scintillators and β-particles from tritium solution were used for this purpose.</p> <p> The tritium β-particles have a very short range (about 5 μm in water), and the surface area of contact between the tritium bearing fluid and the scintillator bearing phase is expected to be proportional to the scintillation count rate, which in turn is proportional to the number of betas crossing the interface from a very thin region.</p> <p> To test this hypothesis, two phases were placed together in a cylindrical plexiglas container, which in turn was placed in an aluminum light-tight housing. The housing also enclosed the photo-multiplier tube (PMT). Pulses corresponding to scintillations due to β absorption were taken from the PMT and fed to a suitable electronic circuit. The count rate was obtained with a multi-channel analyser.</p> <p> It was found that the count rate is a linear function of interfacial area between the tritium bearing fluid and the scintillating material. Some deviation from linearity was however noticed at very low tritium concentration. The count rate remained the same for a given interfacial area regardless of orientation of the surface(s) with respect to the photocathode face.</p> <p> This appeared to confirm the hypothesis that interfacial area could be measured in systems of this type by measuring the scintillation count rate.</p> / Thesis / Master of Engineering (MEngr)

The purpose of the research is to observe and describe the ethnic composition of Hamilton, using 1986 census data. To identify salient spatial trends, two main types of analyses are employed: The Segregation Index and the Location Quotient. Elementary statistics, such as mean and percentages were also calculated. Eight ethnic groups and 88 census tracts were used. These techniques involved the use of 'ethnic origin' data, from Canada's 1986 census. This was the first enumeration that included multiple ethnic origins, previously only the single, paternal lineage was recorded. The reseach demonstrates that Hamilton's ethnic groups exhibit varing degrees of clustering. The city can therefore, be described as a cultural mosaic, with high concentrations of ethnic groups occurring throughout. Conclusions shall be reached as to the possible causes of the observed patterns and shall be related to the choices and contstraints of the particular ethnic groups involved. / Thesis / Candidate in Philosophy

<p> Using a potentiometric method on 10^-4M and 10^-5M Al(NO3)3 solutions at constant ionic strength (0.1 M KNO3) and temperature (25°C), titration curves were defined and examined with respect to three variables (total aluminum concentration, pH range, and time) in order to assess the reversibility of the aqueous system.</p> <p> Increasing pH titration interval decreased reversibility while increasing time interval led to a slight increase in reversibility. Decreasing the total aluminum concentration also slightly improved reversibility. Overall, the reversibility of the system was observed to be poor.</p> <p> Computer models were compared to experimental titration data in order to derive the speciation schemes which best fit the data. Polynuclear hydrolysis schemes fit the data best for the concentration levels as follows: Al^3+, Al(OH)4^-, and Al6(OH)15^3+ for 10^-5M Alt. Al^3+, Al(OH)4^-, and Al8(OH)20^4+ and/or Al13(OH)32^7+ for 10^-4M Alt. / Thesis / Master of Science (MSc)

<p> This study describes the analysis of orientation of elongate quartz grains in massive turbidite sandstones from the Chetco Formation (Jurassic) of southwestern Oregon. Inferences on depositional fabric of this resedimented facies are made.</p> <p> Grain orientation in the plane parallel to bedding is generally not highly significant statistically, and current direction, supplied by imbrication, is not persistent vertically through the beds. However, a rotation pattern of current direction in each bed is detected.</p> <p> Variations in orientation distribution could represent variations in sediment concentration of the flow and in the rate of deposition.</p> / Thesis / Bachelor of Science (BSc)

No description available.