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Quantum phase transitions occur as a result of competing ground states. The focus of the present work is to understand quantum criticality and its consequences when the competition is between insulating and metallic ground states. Metal-insulator transitions are studied by means of electronic transport measurements and quantum critical points are approached by applying hydrostatic pressure in two different compounds namely Eu$_2$Ir$_2$O$_7$ and FeCrAs. The former is a ternary metal oxide and the latter is a ternary metal pnictide. A major component of this work was the development of the ultra-high pressure measurements by means of Anvil cells. A novel design is introduced which minimizes the alignment accessory components hence, making the cell more robust and easier to use. Eu$_2$Ir$_2$O$_7$ is a ternary metal oxide and a member of the pyrochlore iridate family. Resistivity measurements under pressure in moissanite anvil cells show the evolution of the ground state of the system from insulating to metallic. The quantum phase transition at $P_c\sim6$ GPa appears to be continuous. A remarkable correspondence is revealed between the effect of the hydrostatic pressure on Eu$_2$Ir$_2$O$_7$ and the effect of chemical pressure by changing the R size in the R$_2$Ir$_2$O$_7$ series. This suggests that in both cases the tuning parameter controls the $t_{2\textrm{g}}$ bandwidth of the iridium $5d$ electrons. Moreover, hydrostatic pressure unveils a curious cross-over from incoherent to conventional metallic behaviour at a $T^* >$ 150 K in the neighbourhood of $P_c$, suggesting a connection between the high and low temperature phases. The possibility of a topological semi-metallic ground state, predicted in recent theoretical studies, is explained. FeCrAs is a ternary metal pnictide with Fermi liquid specific heat and susceptibility behaviour but non-metallic non-Fermi liquid resistivity behaviour. Characteristic properties of the compound are explained and compared to those of superconducting pnictides. Antiferromagnetic (AFM) order sets in at $\sim125$ K with the magnetic moments residing on the Cr site. Pressure measurements are carried out in moissanite and diamond anvil cells in order to suppress the AFM order and resolve the underlying electronic transport properties. While AFM order is destroyed by pressure, the non-metallic non-Fermi liquid behaviour is shown to be robust against pressure.

Quantum phase transitions occur as a result of competing ground states. The focus of the present work is to understand quantum criticality and its consequences when the competition is between insulating and metallic ground states. Metal-insulator transitions are studied by means of electronic transport measurements and quantum critical points are approached by applying hydrostatic pressure in two different compounds namely Eu$_2$Ir$_2$O$_7$ and FeCrAs. The former is a ternary metal oxide and the latter is a ternary metal pnictide. A major component of this work was the development of the ultra-high pressure measurements by means of Anvil cells. A novel design is introduced which minimizes the alignment accessory components hence, making the cell more robust and easier to use. Eu$_2$Ir$_2$O$_7$ is a ternary metal oxide and a member of the pyrochlore iridate family. Resistivity measurements under pressure in moissanite anvil cells show the evolution of the ground state of the system from insulating to metallic. The quantum phase transition at $P_c\sim6$ GPa appears to be continuous. A remarkable correspondence is revealed between the effect of the hydrostatic pressure on Eu$_2$Ir$_2$O$_7$ and the effect of chemical pressure by changing the R size in the R$_2$Ir$_2$O$_7$ series. This suggests that in both cases the tuning parameter controls the $t_{2\textrm{g}}$ bandwidth of the iridium $5d$ electrons. Moreover, hydrostatic pressure unveils a curious cross-over from incoherent to conventional metallic behaviour at a $T^* >$ 150 K in the neighbourhood of $P_c$, suggesting a connection between the high and low temperature phases. The possibility of a topological semi-metallic ground state, predicted in recent theoretical studies, is explained. FeCrAs is a ternary metal pnictide with Fermi liquid specific heat and susceptibility behaviour but non-metallic non-Fermi liquid resistivity behaviour. Characteristic properties of the compound are explained and compared to those of superconducting pnictides. Antiferromagnetic (AFM) order sets in at $\sim125$ K with the magnetic moments residing on the Cr site. Pressure measurements are carried out in moissanite and diamond anvil cells in order to suppress the AFM order and resolve the underlying electronic transport properties. While AFM order is destroyed by pressure, the non-metallic non-Fermi liquid behaviour is shown to be robust against pressure.

This thesis work presents the analysis of Oscillometric blood pressure pulse waveform under different pressure points (Systolic, Mean Arterial, and Diastolic Pressures). Pulse waveforms' characteristics were determined from the waveforms at three different pressures and are compared for subjects at three different age groups. Estimation of blood pressure using a morphology based approach was done by using the change of pulse waveform characteristics at different pressure points. Pulse waveforms' characteristics that were obtained from pulse waveforms are utilized to estimate SBP, MAP, and DBP. The estimates obtained with pulse morphology based technique are compared with a BP measurement device and Maximum Amplitude Algorithm. Maximum slope of the pulse was also used for blood pressure estimation. The effect of movement and breathing on proposed method and MAA were compared and it was observed that breathing artifacts affect less the proposed method.

Electrical resistivity is an important indicator of metal thin film quality. In this study, the influence of argon working pressure on the properties of metal thin films was evaluated, and the thickness effect on the resistivity of metal thin films was investigated. The sputtered thin film resistivity performances of seven metals as a function of argon pressure were measured, and the results turned out that the argon pressure was vital to film quality. Further investigation on sputtered chromium thin films using XRD, SEM and XPS revealed that the argon pressure influences the microstructure of sputtered metal thin films. Different microstructure is the reason for different resistivity performances, and John Thornton's "Zone Model" explains all these behaviours well. The resistivity of aluminum and chromium thin films with thickness from 15 to 150 nm were compared, the resistivity change significantly. The scaling trends are different for different metals. / Materials Engineering

Thesis (MAppSci in Physiotherapy) -- University of South Australia, 1994

Thesis (MAppSci in Physiotherapy) -- University of South Australia, 1994