Association of Mothers' Perception of Neighborhood Quality and Maternal Resilience with Risk of Preterm Birth.

We examined the associations of mothers' perception of neighborhood quality and maternal resilience with risk of preterm birth and whether maternal resilience moderated the effect of neighborhood quality perception. We analyzed data from 10,758 women with singleton births who participated in 2010-2012 Los Angeles Mommy and Baby surveys. Multilevel logistic regression models assessed the effects of mothers' perception of neighborhood quality and maternal resilience on preterm birth (yes/no), controlling for potential confounders and economic hardship index, a city-level measure of neighborhood quality. Interaction terms were assessed for moderation. Mothers' perception of neighborhood quality and maternal resilience were each uniquely associated with preterm birth, independent of potential confounders (p-values < 0.05). The risk of preterm birth among mothers who perceived their neighborhood as of poor quality was about 30% greater compared to mothers who perceived their neighborhood as of good quality; the risk was 12% greater among mothers with low resilience compared to those with high resilience. Effects of neighborhood quality were not modified by maternal resilience. The findings suggest that mothers' perception of neighborhood quality and resilience are associated with the risk of preterm birth. Further research should explore whether initiatives aimed at improving neighborhood quality and women's self-esteem may improve birth outcomes

Mitochondrial Outer Membrane Permeability Change and Hypersensitivity to Digitonin Early in Staurosporine-induced Apoptosis

We have shown here that the apoptosis inducer staurosporine causes an early decrease in the endogenous respiration rate in intact 143B.TK- cells. On the other hand, the activity of cytochrome c oxidase is unchanged for the first 8 h after staurosporine treatment, as determined by oxygen consumption measurements in intact cells. The decrease in the endogenous respiration rate precedes the release of cytochrome c from mitochondria. Moreover, we have ruled out caspases, permeability transition, and protein kinase C inhibition as being responsible for the decrease in respiration rate. Furthermore, overexpression of the gene for Bcl-2 does not prevent the decrease in respiration rate. The last finding suggests that Bcl-2 acts downstream of the perturbation in respiration. The evidence of normal enzymatic activities of complex I and complex III in staurosporine-treated 143B.TK- osteosarcoma cells indicates that the cause of the respiration decrease is probably an alteration in the permeability of the outer mitochondrial membrane. Presumably, the voltage-dependent anion channel closes, thereby preventing ADP and oxidizable substrates from being taken up into mitochondria. This interpretation was confirmed by another surprising finding, namely that, in staurosporine-treated 143B.TK- cells permeabilized with digitonin at a concentration not affecting the mitochondrial membranes in naive cells, the outer mitochondrial membrane loses its integrity; this leads to a reversal of its impermeability to exogenous substrates. The loss of outer membrane integrity leads also to a massive premature release of cytochrome c from mitochondria. Most significantly, Bcl-2 overexpression prevents the staurosporine-induced hypersensitivity of the outer membrane to digitonin. Our experiments have thus revealed early changes in the outer mitochondrial membrane, which take place long before cytochrome c is released from mitochondria in intact cells

KINEMATIC RELEVANCE OF SHORT APPROACH JUMPS AS A TRAINING TOOL FOR COMPETITION LONG JUMPING

Training for the long jump involves short approach jumps which are often assumed to replicate full approach jump take-0%. The aim of this study was to compare directly the kinematics of short and full approach jumps. One elite female long jumper completed seven 10 step approach jumps during one training session, and five full approach jumps in an international competition. Video from a fixed camera was digitised and kinematic variables for the final touchdown calculated. Approach run step kinematics were obtained from a panning camera. Statistically significant (p < 0.05) differences were identified in approach step characteristics and in horizontal velocity, but none were found in vertical velocity generated. Results indicate short approach jumps are a useful tool for generation of vertical velocity but do not directly replicate full approach jumps in approach or take off

Biomechanical Factors Affecting Individuals’ Performance in Sprint Kayaking

Sprint kayaking is a complex skill performed in a complex environment. This thesis aimed to identify and assess key parameters of performance and to understand the impact of the equipment used in order to better inform elite-level coaching. Current elite sprint kayak coaching knowledge was documented through interviews and compared with biomechanics literature. Six mechanical factors were identified as important for performance: water interaction, boat connection, athlete kinematics, stroke rate (SR)/ distance per stroke (DPS), force/power and the influence of weather conditions. Athlete individuality in particular was considered highly important but was under-represented in academic literature. These conclusions informed the subsequent experimental studies, ensuring value to coaches and a positive impact on elite athlete performance. Force-velocity and power-velocity profiles for an iso-inertial ergometer (n = 39), as well as performance profiles on-water (n = 25), were subsequently created for a group of elite, sub-elite and club sprint kayakers. Power and theoretical maximal force production (F0) were found to differentiate between groups, with elite athletes exhibiting the highest power (elite: 48.5 ± 8.8; sub-elite: 41.0 ± 7.9; club: 38.9 ± 7.2 W·kg-0.67) and force (elite: 17.6 ± 2.7;sub-elite: 14.5 ± 1.7; club: 14.2 ± 1.9 N·kg-0.67). Individual analysis of a subgroup of 18 athletes correlated F0 and V0 (theoretical maximal velocity) with stroke power across multiple trials per athlete. Eight athletes were found to exhibit trends of the group with a statistically significant positive correlation between F0 and stroke power, while for five athletes higher V0 correlated statistically significantly with higher stroke power. On-water at group level, boat velocity was found to exhibit a stronger correlation with stroke rate (SR) than with distance per stroke (DPS; r = 0.85 vs 0.67). At individual level, DPS showed a higher correlation with boat velocity for eight of the 15 athletes in the subgroup tested, highlighting the importance of athlete individuality, in research and in elite training environments. Combining data from the two environments found strong correlations between power, F0 and boat velocity, indicating the value of this ergometer profiling to understand force and power in a kayak-like movement. The final study used individualised measures of variability to define whether changes in paddle length on the ergometer resulted in notable differences in performance measured by power, F0 and V0. Changes in paddle length of 1% relative to length normally used by the athlete, equivalent to around 2 cm, resulted in ‘notable’ improvements in stroke power for three athletes and caused changes in F0 or V0 in six of the ten athletes tested. This thesis developed pertinent research questions based on key variables to performance, as identified from coaching interviews. Large differences were found in these simple mechanical parameters when analysed at individual, relative to group, level. Similar individual differences were found in response to paddle length changes on an ergometer. Based on the thesis findings, a set of recommendations for coaches have been presented, which it is hoped will facilitate the application of the research to improving on-water performance

THE EFFECT OF BUNGEE TENSION ON POWER PROFILING IN KAYAK ERGOMETRY

In water sports, where accurate biomechanical measurement in situ is difficult, ergometers are frequently used to test athletes. Many kayak ergometer designs involve a bungee to assist in returning the athlete/paddle to the correct position for the next stroke. The study’s aim was to investigate the effect of bungee tension on the ergometermeasured maximal power-velocity profile of three experienced male kayak athletes. Bungee tension influenced the power-velocity profile, reducing peak power measured by up to 328.4 W from optimal to least optimal tension. Athlete’s anecdotally preferred feel tensions may be optimal, thus these tensions should be considered in investigating power-related factors

Catalysts Development and Mechanistic Study of Ethanol Steam Reforming for Low Temperature H2 Production

Ph.DDOCTOR OF PHILOSOPH

PLANTAR PRESSURE CHARACTERISTICS OF SKELETON ATHLETES DURING THE PUSH START ON A DRY-LAND TRAINING SURFACE

The purpose of this study was to characterise plantar pressure maps through the push start of top-level skeleton athletes. The push start is a vital component in skeleton to achieve success, and therefore, a focus on the performance characteristics of the push start could help to reduce the run time and increase the athlete’s initial velocity. Five international skeleton athletes each performed 3-5 push starts on a dry-land push track with wireless pressure insoles. Key differences in 2-d plantar pressure patterns were identified with a confidence interval of

Short-term serotonergic but not noradrenergic antidepressant administration reduces attentional vigilance to threat in healthy volunteers

Anxiety is associated with threat-related biases in information processing such as heightened attentional vigilance to potential threat. Such biases are an important focus of psychological treatments for anxiety disorders. Selective serotonin reuptake inhibitors (SSRIs) are effective in the treatment of a range of anxiety disorders. The aim of this study was to assess the effect of an SSRI on the processing of threat in healthy volunteers. A selective noradrenergic reuptake inhibitor (SNRI), which is not generally used in the treatment of anxiety, was used as a contrast to assess the specificity of SSRI effects on threat processing. Forty-two healthy volunteers were randomly assigned to 7 d double-blind intervention with the SSRI citalopram (20 mg/d), the SNRI reboxetine (8 mg/d), or placebo. On the final day, attentional and interpretative bias to threat was assessed using the attentional probe and the homograph primed lexical decision tasks. Citalopram reduced attentional vigilance towards fearful faces but did not affect the interpretation of ambiguous homographs as threatening. Reboxetine had no significant effect on either of these measures. Citalopram reduces attentional orienting to threatening stimuli, which is potentially relevant to its clinical use in the treatment of anxiety disorders. This finding supports a growing literature suggesting that an important mechanism through which pharmacological agents may exert their effects on mood is by reversing the cognitive biases that characterize the disorders that they treat. Future studies are needed to clarify the neural mechanisms through which these effects on threat processing are mediated