Electrical and material properties of thin film perovskites

PhD ThesisThis thesis presents a study of negative capacitance in the robust perovskite BaTiO3. Negative capacitance is an unstable state in ferroelectrics, which explains why there is a lack of experimental evidence in the literature. A positive capacitance in a series capacitor configuration allows stabilisation of negative capacitance. The key finding is the stabilisation of negative capacitance at room temperature in BaTiO3. Temperature constraints in back-end-of-line processing should be at 500 °C or below in order to avoid diffusion of dopants and to inhibit high resistivity silicide phases. Three deposition techniques, pulsed laser deposition, atomic layer deposition and sputter deposition are used to investigate the material and electrical properties of perovskites for back-end integration within this temperature constraint. SrTiO3, Ba0.8Sr0.2TiO3 and BaTiO3 are all explored as possible solutions for tunable capacitance under low temperature processing. Evidence is shown for SrTiO3 displaying fully crystallised structures through pulsed laser deposition at 500 °C growth temperature. A refined model of effective oxide thickness is used to calculate interfacial layers that impact metal-oxide-semiconductor capacitors. The model is applied to SrTiO3 metal-insulator-metal capacitors in terms of a dead layer. Calculation of the dead layer thickness, which has been previously unattainable using solely the series capacitance model, is carried out using the effective oxide thickness model. However, transmission electron microscopy images suggest that a physical layer of ‘dead’ material is abesnt in the capacitors. The results support the hypothesis of an intrinsic explanation to the dead layer phenomenon. ii Finally, pulsed laser deposited BaTiO3 is explored in terms of ferroelectricity when integrated with Si using Pt/Ti/SiO2/Si substrates. Here, a mixed phase relationship is shown in the films of BaTiO3 in which the cubic phase, responsible for paraelectricity, dominates at room temperature. Increasing film thickness also correlates with higher remnant polarization in the films. The result confirms a size driven phase transition in thin film BaTiO3 which has preveously been studied on perovskite free-standing films or nanoparticles

Non-global logarithms in inter-jet energy flow with kt clustering requirement

Recent work in inter-jet energy flow has identified a class of leading logarithms previously not considered in the literature. These so-called non-global logarithms have been shown to have significant numerical impact on gaps-between-jets calculations at the energies of current particle colliders. Here we calculate, at fixed order and to all orders, the effect of applying clustering to the gluonic final state responsible for these logarithms for a trivial colour flow 2 jet system. Such a clustering algorithm has already been used for experimental measurements at HERA. We find that the impact of the non-global logarithms is reduced, but not removed, when clustering is demanded, a result which is of considerable interest for energy flow observable calculations.Comment: 13 pages, 4 figure

Specificity and transfer of lower-body strength: influence of bilateral or unilateral lower-body resistance training

Appleby, BB, Cormack, SJ, and Newton, RU. Specificity and transfer of lower-body strength: Influence of bilateral or unilateral lower-body resistance training. J Strength Cond Res 33(2): 318-326, 2019-To examine the development of lower-body strength using either bilateral or unilateral resistance training. Developmental rugby players (n = 33; mean training age = 5.4 ± 2.9 years; 1 repetition maximum [1RM] 90° squat = 178 ± 27 kg) completed an 18-week randomized controlled training design (bilateral group [BIL], n = 13; unilateral group [UNI], n = 10; comparison, n = 10). The 8-week training phase involved 2 lower-body, volume-load matched resistance sessions per week (6-8 sets × 4-8 reps at 45-88% 1RM), differing only in the prescription of a bilateral (back squat) or unilateral (step-up) resistance exercise. Maximum strength was assessed by a randomized order of 1RM back squat and step-up testing and analyzed for within- and between-group differences using effect sizes (ES ± 90% confidence limits [CL]). Both training groups showed practically important improvements in their trained exercise (ES ± 90% CL: BIL = 0.67 ± 0.48; UNI = 0.74 ± 0.38) with transfer to their nontrained resistance exercise (BIL step-up = 0.27 ± 0.39: UNI squat = 0.42 ± 0.39). The difference between groups in adaptation of squat strength was unclear (BIL ES = -0.34 ± 0.55), while the UNI group showed an advantage in step-up training (ES = 0.41 ± 0.36). The results demonstrate that practically important increases in lower-body strength can be achieved using bilateral or unilateral resistance training and development of that strength may be expressed in the movement not trained, supporting the transfer of strength training between exercises of similar joint movements and muscles. Coaches may choose to incorporate unilateral strength training where the prescription of bilateral training may be inhibited

Health visiting - the end of a UK wide service?

In 1997 Health Visiting was deemed by New Labour to be an important player in reducing health inequalities. It was acknowledged that if Health Visiting was to fulfill this vision it would have to work out with its traditional child health role and also engage with groups, communities and populations to tackle the determinants of ill health. Twelve years on, external factors such as, NHS cut backs, recent changes to how Health Visitors are regulated throughout the UK and devolved Health Visiting policy making structures have led to the rapid demise in status and legitimacy of Health Visiting and its wider public health role. This article argues that the unintended consequences of devolved Health Visiting policy has resulted in 3 recent community nursing and health-visiting reviews in Scotland and England which have made divergent policy recommendations about the role of the Health Visitor in tackling health inequalities. The recommendations outlined in the Scottish review in particular threatened to jeopardise the very future provision of a UK wide Health Visiting service. If Health Visiting is to survive as a UK wide entity, a radical independent rethink as to its future direction and its public health role is urgently required

Kinetics and kinematics of the squat and step-up in well-trained rugby players

The purpose of this study was to compare and contrast the kinetics and kinematics of squat and step-up performance in well-trained athletes. Triaxial ground reaction force (GRF) and 3D kinematic data were collected in 4 maximal effort repetitions each at 70, 80, and 90% of 1 repetition maximum (1RM) of squat and step-up. The difference in concentric phase kinetics and kinematics between the squat and step-up was compared using effect sizes (ES ± 90% confidence limits [CLs]) classified as: less than 0.2 as trivial; 0.2-0.6 as small; 0.6-1.2 as moderate; and 1.2-2.0 as large. Where the 90% CL crossed negative and positive 0.2 values, the effect was considered unclear.n Ground reaction force was higher for the step-up than squat at all relative intensities per leg (peak GRF ES: 2.56 ± 0.19 to 2.70 ± 0.37; average GRF ES: 1.45 ± 0.27 to 1.48 ± 0.29). Per leg, the difference in concentric impulse favored the step-up compared with squat at 70% 1RM (ES = 0.71 ± 0.40) and 80% 1RM (ES = 0.30 ± 0.41) but was unclear at 90% 1RM (ES = -0.25 ± 0.47). The squat peak velocity was greater compared with step-up at all intensities (ES = -1.74 ± 0.48 to -1.33 ± 0.48). Despite a lower external load and a single base of support, per leg, the step-up produced comparable GRF because the squat suggesting overload provided by the step-up is sufficient for maximal strength development. Future research may investigate the efficacy of the step-up in a training intervention for the development of lower-body strength

Reliability of squat kinetics in well-trained rugby players: Implications for monitoring training

The aim of this study was to determine the within-session reliability in kinetic variables of the squat in well-trained athletes during a typical resistance training protocol. Fifteen subjects completed 2 testing sessions. Session 1 was establishment of 1 repetition maximum (1RM) squat, and session 2 involved 2 sets of 2 maximal effort repetitions of the squat at 70, 80, and 90% of 1RM with 3D motion analysis and ground reaction force (GRF) measurement using 2 in-ground triaxial force plates. Reliability was calculated using typical error ± 90% confidence limits, expressed as the coefficient of variation and intraclass correlation coefficient. The smallest worthwhile change (SWC%), calculated as 0.2 × between-subject SD, was used to determine the smallest important change in performance. Peak GRF and average GRF were found to have acceptable measures of reliability with the combined left and right leg average GRF capable of detecting the SWC. Independent limb contributions were reliable (left and right, or dominant and nondominant). Reliable kinetics can be obtained in back squat performance typical of a resistance training session in well-trained athletes. This suggests that coaches integrating force plate technology within training sessions may effectively capture between 1 and 6 training sets among several athletes, facilitating analysis and intervention on larger data sets

Unilateral and bilateral lower-body resistance training does not transfer equally to sprint and change of direction performance

Given maximal strength can be developed using bilateral or unilateral resistance training, the purpose of this study was to determine the magnitude of transfer of unilateral or bilateral resistance training to sprint and change of direction (COD) performance. Thirty-three trained participants (average training age = 5.4 ± 2.9 years and 1 repetition maximum [1RM] 90° squat = 177.6 ± 26.7 kg) completed either a bilateral group (BIL, n = 13), unilateral (UNI, n = 10), or comparison (COM, n = 10) 18-week randomized controlled training design. Training involved 2 lower-body, volume-load-matched resistance sessions per week (6-8 sets × 4-8 reps at 45-88% 1RM), differing only in the prescription of a bilateral (squat) or unilateral (step-up) resistance exercise. Strength was assessed through 1RM squat and step-up, in addition to 20-m sprint and a customized 50° COD test. The effect size statistic ± 90% confidence limit (ES ± CL) was calculated to examine the magnitude of difference within and between groups at each time point. BIL and UNI groups improved their trained and nontrained strength exercise with an unclear difference in adaptation of squat strength (ES = -0.34 + 0.55). Both groups improved 20-m sprint (ES: BIL = -0.38 ± 0.49 and UNI = -0.31 ± 0.31); however, the difference between the groups was unclear (ES = 0.07 ± 0.58). Although both groups had meaningful improvements in COD performance, bilateral resistance training had a greater transfer to COD performance than unilateral resistance training (between-groups ES = 0.59 ± 0.64). Both bilateral and unilateral training improved maximal lower-body strength and sprint acceleration. However, the BIL group demonstrated superior improvements in COD performance. This finding potentially highlights the importance of targeting the underlying physiological stimulus that drives adaptation and not exercise selection based on movement specificity of the target performance

Can a specific neck strengthening program decrease cervical spine injuries in a men\u27s professional rugby union team? A retrospective analysis

Cervical spine injuries in Rugby Union are a concerning issue at all levels of the game. The primary aim of this retrospective analysis conducted in a professional Rugby Union squad was to determine whether a 26-week isometric neck strengthening intervention program (13-week strengthening phase and 13- week maintenance phase) was effective in reducing the number and severity of cervical spine injuries. The secondary aim was to determine whether at week five, where the program had been the similar for all players, there was increased isometric neck strength. All 27 players who were common to both the 2007- 2008 and 2008-2009 seasons were included in this analysis and data was extracted from a Sports Medicine/Sports Science database which included the squad\u27s injury records. Primary outcome variables included; the number of cervical spine injuries and the severity of these injuries as determined by the total number of days lost from training and competition. Secondary outcome variables included isometric neck strength in flexion, extension and left and right lateral flexion. Using nonparametric statistical methods, no significant differences were evident for the total number of cervical spine injuries (n = 8 in 2007-2008, n = 6 in 2008-2009) or time loss due to these injuries (100 days in 2007-2008, 40 days in 2008-2009). However, a significant (p = 0.03) reduction in the number of match injuries was evident from 2007-2008 (n = 11) to 2008-09 (n = 2). Nonsignificant increases in isometric neck strength were found in all directions examined. A significant reduction in the number of match injuries was evident in this study. However, no other significant changes to primary outcome variables were achieved. Further, no significant increases in isometric neck strength were found in this well-trained group of professional athletes

Proton Spin-Lattice Relaxation of Water Molecules in Ferrous-Ferric/Agarose Gel System

Proton spin-lattice relaxation time (T1) of water in aqueous solutions of ferrous and ferric ions and in the corresponding agarose gel systems have been studied in the light of NMR relaxation theory. The theoretical analysis of 1/T1\u27s has revealed that, at the microscopic level, changes in the solvation states of paramagnetic ions in aqueous or gel environment are greater than difference in the paramagnetism between ferric and ferrous ions. The former change is the primary factor for the exhibition of radiation effect. At the phenomenological level, we have confirmed and demonstrated that: (1) Radiation effect is almost exclusively exhibited through changes in 1/T1 caused by the interactions between water proton and ferrous or ferric ions; and (2) fraction of conversion of ferrous to ferric ions induced by radiation is the “true” representation of the spatial distribution of radiation dose