An investigation into the effect on skin surface temperature of three cryotherapy modalities

OBJECTIVE: To investigate the comparative cooling effect at the knee, of Crushed Ice and two commonly used commercial cryotherapy modalities, following a clinically relevant application of 20 minutes. DESIGN: Within subjects, randomised cross over design. SETTING: University Laboratory PARTICIPANTS: Eleven healthy male participants MAIN OUTCOME Measures: Skin temperature over the anterior knee measured by thermal imaging camera. RESULTS: Mean absolute baseline skin surface temperature (Tsk) was 28.4ºC (±1.2 ºC). The greatest reduction in Tsk was produced by Crushed Ice D14.6 ºC (±3.7 ºC) resulting in an absolute Tsk of 13.8 ºC; followed by Ice Man D12.3 ºC (±2.4 ºC) resulting in an absolute Tsk of 16.1ºC and then Arctic Flow D4.9 ºC (±1.3 ºC) resulting in an absolute Tsk of 23.5ºC. One-way ANOVA revealed significant differences (p<.05) between modalities for change in Tsk. CONCLUSIONS: Crushed Ice and Ice Man produced very similar results following a 20 minute application to healthy adult male knees, however only Crushed Ice resulted in a skin temperature in the desired 10-15°C therapeutic range, results for Ice Man were just above this range. The resultant skin temperature following a similar application of Arctic Flow was well above the therapeutic range

Investigation of transient and safety issues in gas insulated systems

This thesis investigates the occurrence, characteristics and effects of Very Fast Transients (VFTs) associated with disconnector switching operations in Gas Insulated Substations. VFTs are analysed and efforts are made to elucidate their behaviour through advanced simulation techniques. The initial motivation for this work was the occurrence of a surface flashover at a spacer, leading to a prolonged outage of the circuit in question and a significant repair effort. While post failure investigations were carried out by the manufacturer and yielded no significant observations, through modelling and measurements efforts while working towards this thesis, a phenomenon that could have led or contributed to the failure. VFTs at a live, operational 400kV Substation (un-named for confidentiality but termed throughout as Substation ‘A’) are quantified through both modelling and measurements. Significant progress in the modelling of VFTs and TEVs is demonstrated. Numerical Electromagnetic Analysis is shown to be most effective method in studying the behaviour of the GIS and earthing systems. Multiple NEA techniques are utilised, all solving a full-Maxwell’s equations through a Wave equation. The behaviour of the system (both internally and externally) is captured with great accuracy and lucidity, without the need to use analytic approximations or assumed parameters, which has traditionally been the case. Detailed models were built using equipment drawings from Substation ‘A’ for the GIB, spacer-flange assembly, double-elbow assembly, disconnector, gas to air bushing. Frequency and time domain behaviour is analysed and a potential contributor to the failure at Substation ‘A’ is identified. Furthermore, elements of the earthing system were evaluated for effectiveness in mitigating TEVs. The methods highlight some of flaws and inaccuracies that are present with existing ‘standard practice’ modelling efforts. The need for circuit-based modelling for VFT studies is apparent, as NEA techniques at very high frequencies are limited in their interaction with the wider system. Efforts are therefore made to enhance circuit-based models; utilising NEA methods and Vector Fitting to produce accurate, large bandwidth equivalent circuits, which demonstrate the computed frequency responses of the various GIS equipment types studied. Vector Fit models at lower orders of approximation are prone to unstable time domain responses, leading to numerical oscillations or even a complete divergence from a solution. A method was developed to identify model orders that demonstrate stability in the time domain, allowing the lowest model order of approximation to be selected, thereby reducing the additional computational requirements of very high orders of approximation, while retaining accuracy and stability in the time and frequency domains. The conversion process is augmented with a new method for identifying model orders that will be stable in the time domain. Several measurement techniques and sensors were developed to capture the entire cycle of transients associated with disconnector operations. Device prototypes were designed and optimised through NEA/circuit-based modelling, prior to undergoing laboratory-based measurements. Laboratory based testing was conducted using a custom built, half scale GIB, with impedance matching cones at each end to allow measurement and signal generating equipment to be connected with minimal interference. While, essential, laboratory-based measurements will never replicate the transient and high EMI environmental conditions seen at a live GIS, therefore, the bulk of the measurement efforts were focused on live measurements at Substation ‘A’. Throughout the course of this project several opportunities to undertake measurements were presented and a significant amount of data was recorded. Each measurement also identified areas for improvement of the measurement system

DNA target sequence and FNR-dependent gene expression.

FNR proteins are global transcription regulators that respond to fluctuations in environmental oxygen. They recognise a DNA target consisting of an inverted repeat, TTGATN(1)N(2)N(3)N(4)ATCAA (where N(1-4) represents a non-conserved tetrad, NCT). Analysis of 68 known and predicted FNR sites from the Escherichia coli K12 genome revealed a bias toward A or T at positions N(2) and N(3) of the NCT. The effect of the NCT sequence on FNR-dependent transcription in vivo was assessed using a series of class II and class I model promoters with different NCT sequences. Changing the NCT sequence did not affect basal activity but altered anaerobic induction by as much as an order of magnitude. Thus, the NCT sequence is a fundamental component in setting the dynamic range of the FNR switch

The relationship between oxidised LDL, endothelial progenitor cells and coronary endothelial function in patients with CHD

Objective The balance between coronary endothelial dysfunction and repair is influenced by many protective and deleterious factors circulating in the blood. We studied the relationship between oxidised low-density lipoprotein (oxLDL), circulating endothelial progenitor cells (EPCs) and coronary endothelial function in patients with stable coronary heart disease (CHD). Methods 33 patients with stable CHD were studied. Plasma oxLDL was measured using ELISA, coronary endothelial function was assessed using intracoronary acetylcholine infusion and EPCs were quantified using flow cytometry for CD34+/KDR+ cells. Results Plasma oxLDL correlated positively with the number of EPCs in the blood (r=0.46, p=0.02). There was a positive correlation between the number of circulating EPCs and coronary endothelial function (r=0.42, p=0.04). There was no significant correlation between oxLDL and coronary endothelial function. Conclusions Plasma levels of oxLDL are associated with increased circulating EPCs in the blood of patients with CHD, which may reflect a host-repair response to endothelial injury. Patients with stable CHD had a high prevalence of coronary endothelial dysfunction, which was associated with lower numbers of circulating EPCs, suggesting a mechanistic link between endothelial dysfunction and the pathogenesis of atherosclerosis

Verified Synthesis of Optimal Safety Controllers for Human-Robot Collaboration

In human-robot collaboration, software-based safety controllers are used to improve operational safety, e.g., by triggering shutdown mechanisms or emergency stops to avoid accidents. Complex robotic tasks and increasingly close human-robot interaction pose new challenges to controller developers and certification authorities. Key among these challenges is the need to assure the correctness of safety controllers under explicit (and preferably weak) assumptions. To address this need, we introduce and evaluate a tool-supported approach for safety controller synthesis and deployment. The new approach focuses on human-robot collaboration in manufacturing, and is informed by the process, risk analysis, and relevant safety regulations for the target application. Controllers are selected from a design space of feasible controllers according to a set of optimality criteria, formally verified against correctness criteria, and translated into executable code and validated in a digital twin. The resulting controller can detect the occurrence of hazards, move the process into a safe state, and, in certain circumstances, return the process to an operational state from which it can resume its original task

Quantum Interference Enhances the Performance of Single-Molecule Transistors

An unresolved challenge facing electronics at a few-nm scale is that resistive channels start leaking due to quantum tunneling. This affects the performance of nanoscale transistors, with single-molecule devices displaying particularly low switching ratios and operating frequencies, combined with large subthreshold swings.1 The usual strategy to mitigate quantum effects has been to increase device complexity, but theory shows that if quantum effects are exploited correctly, they can simultaneously lower energy consumption and boost device performance.2-6 Here, we demonstrate experimentally how the performance of molecular transistors can be improved when the resistive channel contains two destructively-interfering waves. We use a zinc-porphyrin coupled to graphene electrodes in a three-terminal transistor device to demonstrate a >104 conductance-switching ratio, a subthreshold swing at the thermionic limit, a > 7 kHz operating frequency, and stability over >105 cycles. This performance is competitive with the best nanoelectronic transistors. We fully map the antiresonance interference features in conductance, reproduce the behaviour by density functional theory calculations, and trace back this high performance to the coupling between molecular orbitals and graphene edge states. These results demonstrate how the quantum nature of electron transmission at the nanoscale can enhance, rather than degrade, device performance, and highlight directions for future development of miniaturised electronics.Comment: 11 pages, 4 figure