Integrated analysis of leaf cell division and growth

This thesis provides a critical analysis of published work undertaken by the author between 2005 and 2019. A major challenge in biology is to understand how buds comprising just a few cells can deform through growth to generate complex plant and animal appendages, like leaves or limbs. In this thesis, I bring together my peer-reviewed publications to focus on how the Arabidopsis first leaf attains its shape through coordinated patterns of orientated growth and cell division. I highlight innovative approaches used to track leaf growth in multiple cell layers and in different genetic backgrounds. I present maps of leaf development which reveal dynamic, spatiotemporal patterns of orientated tissue growth and cell division. I present models developed through collaborations with computer scientists that provide key insights into how leaf shapes are formed during organ morphogenesis via an underlying biochemical-based polarity system that may also be applicable to more complex shape development. I discuss how the patterns of cell division and cell sizes are correlated and present an integrated model that suggests how cell division and growth can be regulated via a dual control mechanism with cross connections. Prior to the work presented here, no previous model had been proposed to explain leaf shape transformation according to biologically validated observations. In this work I assess the impact of this research to the field of plant developmental biology and suggest that the knowledge gained provides valuable information to the plant science community upon which future studies may be based

Benefits of Crank Moment Sonification in Cycling

AbstractIn sports, the provision of augmented feedback is an important means to accelerate learning of new movements. Traditionally, concurrent augmented feedback has been provided verbally or visually. However, more recent studies have shown sonification of data during the movement, i.e. the mapping of a measured variable to parameter of sound, can be very effective to learn temporal aspects of a movement or movement patterns. In this pilot study, it was investigated if learning of complex pushing-pulling action applied to clipless pedals of a cycling ergometer can be enhanced by sonification of the crank moment. Three novice and three experienced cyclists were invited to train a reference crank moment pattern for two consecutive days (a total of twelve training sessions of 60 s each). However, in contrast to the results found in studies on rowing, the applied sonification did not enhance learning compared to visual and verbal instruction only. The lack of learning might be due to an inappropriate sonification design, short training sessions or the high task complexity. Extended studies are needed to draw more significant conclusions

Repeat-pass synthetic aperture sonar micro-navigation using redundant phase center arrays

In this paper, a new algorithm is introduced for high-precision underwater navigation using the coherent echo signals collected during repeat-pass synthetic aperture sonar (SAS) surveys. The algorithm is a generalization of redundant phase center (RPC) micronavigation, expanded to RPCs formed between overlapping pings in repeated passes. For each set of overlapping ping pairs (two intrapass and three interpass), five different RPC arrays can be formed to provide estimates of the vehicle's surge, sway, and yaw. These estimates are used to find a weighted least squares solution for the trajectories of the repeated passes. The algorithm can estimate the relative trajectories to subwavelength precision (on order of millimeters to hundreds of micrometers at typical SAS operating frequencies of hundreds of kilohertz) in a common coordinate frame. This will lead to improved focusing and coregistration for repeat-pass SAS interferometry and is an important step toward repeat-pass bathymetric mapping. The repeat-pass RPC micronavigation algorithm is demonstrated using data collected by the 300-kHz SAS of the NATO Center for Maritime Research and Experimentation (CMRE) Minehunting Unmanned underwater vehicle for Shallow water Covert Littoral Expeditions (MUSCLE)

Timing of Childhood Adversities and Self-Injurious Thoughts and Behaviors in Adolescence

Greater childhood adversity predicts a higher likelihood of later self-injurious thoughts and behaviors (SITB). There is little research focused on whether the timing of childhood adversity predicts SITB. The current research examined whether the timing of childhood adversity predicted parent- and youth-reported SITB at age 12 and 16 years in the Longitudinal Studies of Child Abuse and Neglect (LONGSCAN) cohort (n = 970). We found that greater adversity at age 11–12 years consistently predicted SITB at age 12 years, while greater adversity at age 13–14 years consistently predicted SITB at age 16 years. These findings suggest there may be sensitive periods during which adversity may be more likely to lead to adolescent SITB, which can inform prevention and treatment

Anterior cruciate ligament injuries in Australian football: Should women and girls be playing? You\u27re asking the wrong question

Anterior cruciate ligament (ACL) injuries have been a rising concern in the early years of the women\u27s Australian Football League (AFLW), eliciting headlines of a â € knee crisis\u27 surrounding the league. There has been a focus on female biology as the primary factor driving the high rate of ACL injuries in the AFLW. Emphasising Australian football (AF) as being dangerous predominantly due to female biology may be misrepresenting a root cause of the ACL injury problem, perpetuating gender stereotypes that can restrict physical development and participation of women and girls in the sport. We propose that an approach addressing environmental and sociocultural factors, along with biological determinants, is required to truly challenge the ACL injury problem in the AFLW. Sports science and medicine must therefore strive to understand the whole system of women in AF, and question how to address inequities for the benefit of the athletes. © © Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ

Anterior cruciate ligament injuries in Australian football: Should women and girls be playing? You\u27re asking the wrong question

Anterior cruciate ligament (ACL) injuries have been a rising concern in the early years of the women\u27s Australian Football League (AFLW), eliciting headlines of a â € knee crisis\u27 surrounding the league. There has been a focus on female biology as the primary factor driving the high rate of ACL injuries in the AFLW. Emphasising Australian football (AF) as being dangerous predominantly due to female biology may be misrepresenting a root cause of the ACL injury problem, perpetuating gender stereotypes that can restrict physical development and participation of women and girls in the sport. We propose that an approach addressing environmental and sociocultural factors, along with biological determinants, is required to truly challenge the ACL injury problem in the AFLW. Sports science and medicine must therefore strive to understand the whole system of women in AF, and question how to address inequities for the benefit of the athletes. © © Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ

The impact of compliance with 6-hour and 24-hour sepsis bundles on hospital mortality in patients with severe sepsis: a prospective observational study

INTRODUCTION: Compliance with the ventilator care bundle affects the rate of ventilator-associated pneumonia. It was not known, however, whether compliance with sepsis care bundles has an impact on outcome. The aims of the present study were to determine the rate of compliance with 6-hour and 24-hour sepsis bundles and to determine the impact of the compliance on hospital mortality in patients with severe sepsis or septic shock. METHODS: We conducted a prospective observational study on 101 consecutive adult patients with severe sepsis or septic shock on medical or surgical wards, or in accident and emergency areas at two acute National Health Service Trust Teaching hospitals in England. The main outcome measures were: the rate of compliance with 6-hour and 24-hour sepsis care bundles adapted from the Surviving Sepsis Campaign guidelines on patients' clinical care; and the difference in hospital mortality between the compliant and the non-compliant groups. RESULTS: The median age of the patients was 69 years (interquartile range 51 to 78), and 53% were male. The sources of infection were sought and confirmed in 87 of 101 patients. The chest was the most common source (50%), followed by the abdomen (22%). The rate of compliance with the 6-hour sepsis bundle was 52%. Compared with the compliant group, the non-compliant group had a more than twofold increase in hospital mortality (49% versus 23%, relative risk (RR) 2.12 (95% confidence interval (CI) 1.20 to 3.76), P = 0.01) despite similar age and severity of sepsis. Compliance with the 24-hour sepsis bundle was achieved in only 30% of eligible candidates (21/69). Hospital mortality was increased in the non-compliant group from 29% to 50%, with a 76% increase in risk for death, although the difference did not reach statistical significance (RR 1.76 (95% CI 0.84 to 3.64), P = 0.16). CONCLUSION: Non-compliance with the 6-hour sepsis bundle was associated with a more than twofold increase in hospital mortality. Non-compliance with the 24-hour sepsis bundle resulted in a 76% increase in risk for hospital death. All medical staff should practise these relatively simple, easy and cheap bundles within a strict timeframe to improve survival rates in patients with severe sepsis and septic shock

Prevalence and risk factors for hypertension and association with ethnicity in Nigeria: results from a national survey.

OBJECTIVE: Non-communicable diseases are now a global priority. We report on the prevalence of hypertension and its risk factors, including ethnicity, in a nationally representative sample of Nigerian adults recruited to a survey of visual impairment. METHODS: multi-stage, stratified, cluster random sample with probability proportional to size procedures was used to obtain a nationally representative sample of 13 591 subjects aged ≥ 40 years. Of these, 13 504 (99.4%) had a blood pressure measurement. RESULTS: The prevalence of hypertension was 44.9% [95% confidence interval (CI): 43.5-46.3% ]. Increasing age, gender, urban residence and body mass index were independent risk factors (p < 0.001). The Kanuri ethnic group had the highest prevalence of hypertension (77.5%, 95% CI: 71.0-84.0%). CONCLUSIONS: The high prevalence of hypertension in Nigeria is a cause for concern and suggests that it is inevitable that the impact of hypertension-related ill health is imminent, with the accompanying financial and societal costs to families and the state of Nigeria