Surface plasmon emission and dynamics in active planar media

By reducing the number of dimensions that light can propagate in from three to two, control over the properties of propagation can be achieved. The plasmonic modes of planar metal-dielectric heterostructures will confine light in one dimension, enhancing the electromagnetic fields within the structure. This thesis focuses on two particular aspects of active nanoplasmonics in planar systems, stopped light lasing and plasmons with gain in nonequilibrium graphene. For stopped-light lasing, a plasmonic waveguide mode is designed to have two points of zero group velocity in a narrow frequency range, in order to increase the local density of optical states that a gain medium can emit into. The two stopped light points form a band of slow light that supports a wide range of wavevectors, allowing localisation over a sub-wavelength gain medium and providing the feedback required for lasing. This results in a new type of laser that does not rely on predefined cavity modes, in fact is cavity-free in 2D, dynamically forming its lasing mode about a locally pumped region of carrier inversion. Graphene, a single-atom thick semimetal, provides the ultimate miniaturisation as a truly 2D material. It is shown that graphene can support plasmons with gain, under realistic conditions of collision loss, temperature, doping, and carrier relaxation via amplified spontaneous emission. This is made possible by developing a scheme to evaluate polarisabilities for nonequilibrium carrier distributions, allowing the calculation of the exact RPA complex-frequency plasmon dispersion solutions. The rates of spontaneous emission are calculated and are critically dependant on the exact dispersion relation. The instantaneous rates are found to be 5 times faster than previously reported and, when coupled with phonons, lead to carrier relaxations on 100 fs timescales. The polarisability and relaxation rates must form the basis of any active graphene device, where electromagnetic energy is coupled to an evolving electronic system.Open Acces

Carbohydrate-derived iminium salt organocatalysts for the asymmetric epoxidation of alkenes

A new family of carbohydrate-based dihydroisoquinolinium salts has been prepared and tested for potential as asymmetric catalysts for the epoxidation of unfunctionalized alkene substrates, providing up to 57% ee in the product epoxides

APGEN Version 5.0

Activity Plan Generator (APGEN), now at version 5.0, is a computer program that assists in generating an integrated plan of activities for a spacecraft mission that does not oversubscribe spacecraft and ground resources. APGEN generates an interactive display, through which the user can easily create or modify the plan. The display summarizes the plan by means of a time line, whereon each activity is represented by a bar stretched between its beginning and ending times. Activities can be added, deleted, and modified via simple mouse and keyboard actions. The use of resources can be viewed on resource graphs. Resource and activity constraints can be checked. Types of activities, resources, and constraints are defined by simple text files, which the user can modify. In one of two modes of operation, APGEN acts as a planning expert assistant, displaying the plan and identifying problems in the plan. The user is in charge of creating and modifying the plan. In the other mode, APGEN automatically creates a plan that does not oversubscribe resources. The user can then manually modify the plan. APGEN is designed to interact with other software that generates sequences of timed commands for implementing details of planned activities

Assessing final-year practical work through group projects

The final year project is a valuable research experience for undergraduates and can be one of the most rewarding aspects of their degree course. With increasing student numbers it is becoming more difficult to supervise students effectively, as truly independent enquiry-based working requires significant supervision, time and resource. To address this, the Department of Chemistry at the University of Reading has recently explored the use of group projects for final year practical work. Students work in teams of 3 to 5 and are presented with a research problem to investigate. These are genuine problems where the answer is unknown and the work open-ended. The students must work together to investigate the problem, dividing the work and sharing results in a manner that more closely resembles project working outside of academia. The students’ output is assessed through a variety of means including a group presentation and report. The projects were successful, with all students completing the work to a satisfactory level and developing strong team-working skills. This paper will outline some of the issues faced in the first year of delivery, and the steps taken to alleviate them

Appropriating architecture: violence, surveillance and anxiety in Belfast's Divis Flats

In Belfast in the 1970s and 1980s, a modernist housing scheme became subject to multiple contested appropriations. Built between 1966 and 1972, the Divis Flats became a flashpoint in the violence of the Troubles, and a notorious space of danger, poverty, and decay. The structural and social failings of so many postwar system-built housing schemes were reiterated in Divis, as the rapid material decline of the complex echoed the descent into war in Belfast and Northern Ireland. Competing military and paramilitary strategies of violence refigured the topography of the flats, rendering the balcony walkways, narrow stairs, and lift shafts into an architecture of urban war. The residents viewed the complex as a concrete prison. They campaigned for the complete demolition of the flats, with protests which included attacking the architecture of the flats itself. The competing appropriations of the complex reflect how architecture is remade through use

Review of Michael Reeve, Bombardment, Public Safety and Resilience in English Coastal Communities during the First World War

Review of Michael Reeve, Bombardment, Public Safety and Resilience in English Coastal Communities during the First World War. Cham, Switzerland: Palgrave Macmillan, 202

The effect of cardiopulmonary bypass on blood thiamine concentration and its association with post-operative lactate concentration

Objective: Cardiothoracic surgery is a large field in Australia, and evidence suggests post-cardiopulmonary bypass (CPB) hyperlactataemia is associated with higher morbidity and mortality. Low thiamine levels are a potentially common yet treatable cause of hyperlactataemia and may occur in the setting of exposure to CPB non-biological material. We hypothesized that cardiopulmonary bypass would result in decreased whole-blood thiamine levels, which may therefore result in increased whole-blood lactate levels in the post-operative period. Methods: Adult patients undergoing non-emergent CPB were recruited in a single centre, prospective, analytic observational study at Townsville University Hospital, Australia. The primary outcome was a comparison of pre- and post-CPB thiamine diphosphate level, secondarily aiming to assess any relationship between lactate and thiamine levels. Prospective pre- and post-CPB blood samples were taken and analysed at a central reference laboratory. Results: Data was available for analysis on 78 patients. There was a statistically significant increase in thiamine diphosphate level from pre-CPB: 1.36 nmol/g Hb, standard deviation (SD) 0.31, 95% confidence intervals (CI) 1.29–1.43, to post-CPB: 1.77 nmol/g Hb, SD 0.53, 95% CI 1.43–1.88, p value 0.05) trend in rising whole-blood lactate levels with increasing time. Analysis of lactate levels at varying time periods found a significant difference between baseline measurements and increased levels at 13–16 h (p < 0.05). There was no significant relationship observed between whole-blood thiamine levels and post-operative lactate levels. Conclusion: Whole-blood thiamine levels were found to increase immediately post-CPB in those undergoing elective cardiac surgery. There was no correlation between whole-blood thiamine levels and post-operative arterial lactate levels

The Demands of the Extra-Time Period of Soccer: A Systematic Review

Objective: Soccer match-play is typically contested over 90 min; however, in some cup and tournament scenarios, when matches are tied, they proceed to an additional 30 min, which is termed “extra-time” (ET). This systematic review sought to appraise the literature available on 120-min of soccer-specific exercise, with a view to identifying practical recommendations and future research opportunities. Methods: The review was conducted according to the PRISMA guidelines. Independent researchers performed a systematic search of PubMed, CINAHL, and PsycINFO in May 2019, with the following keywords entered in various combinations: “soccer”, “football”, “extra-time”, “extra time”, “extratime”, “120 minutes”, “120 min”, “additional 30 minutes”, and “additional 30 min”. Results: The search yielded an initial 73 articles. Following the screening process, 11 articles were accepted for analyses. Articles were subsequently organized into the following 5 categories: movement demands of ET, performance responses to ET, physiological and neuromuscular response during ET, nutritional interventions, and recovery and ET. The results highlighted that during competitive match-play, players cover 5%–12% less distance relative to match duration (i.e., meters per minute) during ET compared to the preceding 90 min. Reductions in technical performance (i.e., shot speed, number of passes and dribbles) were also observed during ET. Additionally, carbohydrate provision may attenuate and improve dribbling performance during ET. Moreover, objective and subjective measures of recovery may be further compromised following ET when compared to 90 min. Conclusion: Additional investigations are warranted to further substantiate these findings and identify interventions to improve performance during ET