Brane Tilings, M2-branes and Orbifolds

Brane Tilings represent one of the largest classes of superconformal theories with known gravity duals in 3+1 and also 2+1 dimensions. They provide a useful link between a large class of quiver gauge theories and their moduli spaces, which are the toric Calabi-Yau (CY) singularities. This thesis includes a discussion of an algorithm that can be used to generate all brane tilings with any given number of superpotential terms. All tilings with at most 8 superpotential terms have been generated using an implementation of this method. Orbifolds are a subject of central importance in string theory. It is widely known that there may be two or more orbifolds of a space by a finite group. Abelian Calabi-Yau orbifolds of the form C³/Γ can be counted according to the size of the group |Γ|. Three methods of counting these orbifolds will be given. A brane tiling together with a set of Chern Simons levels is sufficient to define a quiver Chern-Simons theory which describes the worldvolume theory of the M2-brane probe. A forward algorithm exists which allows us to easily compute the toric data associated to the moduli space of the quiver Chern-Simons theory from knowledge of the tiling and Chern-Simons levels. This forward algorithm will be discussed and illustrated with a few examples. It is possible that two different Chern-Simons theories have the same moduli-space. This effect, sometimes known as 'toric duality' will be described further. We will explore how two Chern-Simons theories (corresponding to brane tilings) can be related to each other by the Higgs mechanism and how brane tilings (with CS levels) that correspond to 14 fano 3-folds have been constructed. The idea of 'child' and 'parent' brane tilings will be introduced and we will discuss how it has been possible to count 'children' using the symmetry of the 'parent' tiling

Development of an Environmental Policy for the University of Surrey.

This project, whose aim is expressed in its title of "The Development of an Environmental Policy for the University of Surrey", involved research into the process of integrating environmental management activities into an organisation. At the conceptual level it explored the environmental agenda and various approaches to environmental management. As specific examples it examined two responses to the agenda from within the UK Higher Education sector (University of Surrey) and UK business and industry (Balfour Beatty Major Projects Ltd). The comparison enabled conclusions to be drawn about the most effective method for responding to the demands of the sustainable development agenda through the development and implementation of an environmental policy. At the University of Surrey, the research stimulated the creation of an Environmental Policy Steering Group and three Working Groups explicitly to facilitate a bottom-up approach to the development and implementation of its environmental policy. The early research findings strongly influenced the content and structure of the environmental policy statement that was proposed by these groups and-subsequently approved by appropriate University committees in Spring 1998. In addition, the process undertaken provides further evidence that the success of a bottom-up approach is highly dependent on sufficient top-level support, appropriate institutional arrangements and an appropriate institutional ethos. The research has also involved the development of an environmental procurement policy for Balfour Beatty Major Projects Ltd, which provided an industrial and engineering dimension to the work. Based upon both research and empirical data, a draft environmental procurement policy was proposed for Balfour Beatty Major Projects Ltd. The generic findings from this aspect of the project resulted in the development of a conceptual tri-partite environmental management framework (called "The SMART Approach") and the development of a simple model for an environmental procurement policy. The SMART approach offers guidance for writing the environmental policy statement and assessing its efficacy; presents an approach to establishing environmental impacts; and advocates the involvement of stakeholders to assist with the process of identifying the significance of those impacts. The validity of this model has been demonstrated through its application at the University of Surrey. Exploration of the environmental agenda inevitably focused upon clarifying sustainable development and interpreting the implications for the University of Surrey. The analysis has revealed what can be considered a "lost dimension" to the concept, that of concern for the impoverished and most notably those in the "developing" world. It is argued that institutions in the Higher Education sector can best respond to this agenda by applying the industry concept of "product stewardship" to all activities

The effect of an elevated atmospheric CO(_2) concentration on secondary metabolism and resource allocation in plantago maritima and armeria maritima

There are relatively few reports concerning carbon and nitrogen partitioning into secondary metabolism in plants grown in elevated atmospheric CO(_2). This thesis investigates the effects of changes in atmospheric CO(_2) and soil nitrogen availability on compatible solute accumulation and resource allocation in Plantago maritima and Armeria maritima. It was hypothesised that contrasting metabolic responses to abiotic stress cause a species-specific response in P. maritima and A. maritima in resource allocation. In response to drought, P. maritima accumulates the carbon based compatible Solute sorbitol, whilst A. maritima accumulates the nitrogen based solutes betaine and proline. Over ten weeks, A. maritima was more responsive to changes in C and N availability than P. maritima, especially in the amount of C fixed into leaf matter. After elevated CO(_2) exposure for one year, the biomass of P. maritima increased and of A. maritima decreased, compared to the respective plants at ambient CO(_2). Compatible solute concentrations were increased by drought at ambient CO(_2) but decreased in droughted plants at elevated CO(_2). This was hypothesised to be due to lower transpiration rates. Rates of transpiration in P. maritima decreased in response to elevated CO(_2) but A. maritima did not. Tissue water-potential was also lowered in response to elevated CO(_2). This thesis also examines resource allocation to other major C and N sinks. In P. maritima grown at elevated CO(_2) for one year, total soluble phenolic concentrations increased and the concentration of soluble protein decreased. In A. maritima, phenolic concentrations decreased and protein concentrations increased. The effect of enhanced CO(_2) on the secondary metabolism of P. maritima was investigated in greater detail. Six phenolics were identified using metabolite profiling, namely p-coumaric acid, ferulic acid, caffeic acid, verbascoside, plantamajoside and luteolin. P. maritima exposed to elevated CO(_2) had higher concentrations of some of these individual phenolic compounds and histochemical analysis identified increases in the number of lignified vessels and a decrease of lignified vessel-wall thickness

CHANNEL CODING TECHNIQUES FOR A MULTIPLE TRACK DIGITAL MAGNETIC RECORDING SYSTEM

In magnetic recording greater area) bit packing densities are achieved through increasing track density by reducing space between and width of the recording tracks, and/or reducing the wavelength of the recorded information. This leads to the requirement of higher precision tape transport mechanisms and dedicated coding circuitry. A TMS320 10 digital signal processor is applied to a standard low-cost, low precision, multiple-track, compact cassette tape recording system. Advanced signal processing and coding techniques are employed to maximise recording density and to compensate for the mechanical deficiencies of this system. Parallel software encoding/decoding algorithms have been developed for several Run-Length Limited modulation codes. The results for a peak detection system show that Bi-Phase L code can be reliably employed up to a data rate of 5kbits/second/track. Development of a second system employing a TMS32025 and sampling detection permitted the utilisation of adaptive equalisation to slim the readback pulse. Application of conventional read equalisation techniques, that oppose inter-symbol interference, resulted in a 30% increase in performance. Further investigation shows that greater linear recording densities can be achieved by employing Partial Response signalling and Maximum Likelihood Detection. Partial response signalling schemes use controlled inter-symbol interference to increase recording density at the expense of a multi-level read back waveform which results in an increased noise penalty. Maximum Likelihood Sequence detection employs soft decisions on the readback waveform to recover this loss. The associated modulation coding techniques required for optimised operation of such a system are discussed. Two-dimensional run-length-limited (d, ky) modulation codes provide a further means of increasing storage capacity in multi-track recording systems. For example the code rate of a single track run length-limited code with constraints (1, 3), such as Miller code, can be increased by over 25% when using a 4-track two-dimensional code with the same d constraint and with the k constraint satisfied across a number of parallel channels. The k constraint along an individual track, kx, can be increased without loss of clock synchronisation since the clocking information derived by frequent signal transitions can be sub-divided across a number of, y, parallel tracks in terms of a ky constraint. This permits more code words to be generated for a given (d, k) constraint in two dimensions than is possible in one dimension. This coding technique is furthered by development of a reverse enumeration scheme based on the trellis description of the (d, ky) constraints. The application of a two-dimensional code to a high linear density system employing extended class IV partial response signalling and maximum likelihood detection is proposed. Finally, additional coding constraints to improve spectral response and error performance are discussed.Hewlett Packard, Computer Peripherals Division (Bristol

Exploring New Zealand Paramedic Attitudes Towards Advance Directives: An Ethical Analysis

Paul Davey, Amanda Lees and Rosemary Godbold, 'Exploring New Zealand paramedic attitutes towards advance directives: an ethical analysis', Australasian Journal of Paramedicine, Vol 13(4): 1-10, Article 2, published 1 November 2016. The version of record is available on line via https://ajp.paramedics.org/index.php/ajp/article/view/241/575 © 2016 The Official Journal of Paramedics AustralasiaIntroduction Advance directives are known to present challenging ethical issues in health care practice, however there is a paucity of research into paramedic perspectives of advance directives. In situations where the patient has not considered end-of-life provisions, or is unable to communicate their wishes, this contributes to an ethically complex decision-making environment for practitioners. Ethical deliberation contributes to practitioners’ critical thinking skills and helps prepare them for decision-making under uncertainty. This research aims to highlight and explore underlying values within ethically complex practice-based decisions. Methods An exploratory, interpretive study using the ‘Values Exchange’, a web-based ethical decision-making tool, explored 18 urbanbased New Zealand paramedics’ deliberative perspectives on a controversial end-of-life scenario. Results Thematic analysis of participants’ responses ascertained the breadth of views on advanced directives, with the emergence of three dominant themes; legal tensions, multiple constructs of dignity and seeking solutions that support clinical practice. Conclusion Findings revealed that when considering situations involving advance directives, participants regarded the duty to uphold patient dignity as paramount. There was a desire for greater legal guidance and a call for increased professional education in law and ethics. This study provides insight into New Zealand urban-based paramedics’ views and experiences of this ethically challenging aspect of patient care.Peer reviewe

Specific DNA structural attributes modulate platinum anticancer drug site selection and cross-link generation

Heavy metal compounds have toxic and medicinal potential through capacity to form strong specific bonds with macromolecules, and the interaction of platinum drugs at the major groove nitrogen atom of guanine bases primarily underlies their therapeutic activity. By crystallographic analysis of transition metal-and in particular platinum compound-DNA site selectivity in the nucleosome core, we establish that steric accessibility, which is controlled by specific structural parameters of the double helix, modulates initial guanine-metal bond formation. Moreover, DNA conformational features can be linked to both similarities and distinctions in platinum drug adduct formation between the naked and nucleosomal DNA states. Notably, structures that facilitate initial platinum-guanine bond formation can oppose cross-link generation, rationalizing the occurrence of long-lived therapeutically ineffective monofunctional adducts. These findings illuminate DNA structure-dependent reactivity and provide a novel framework for understanding metal-double helix interactions, which should facilitate the development of improved chromatin-targeting medicinal agent

Identification and predictability of soil quality indicators from conventional soil and vegetation classifications

The physical, chemical and biological attributes of a soil combined with abiotic factors (e.g. climate and topography) drive pedogenesis and some of these attributes have been used as proxies to soil quality. Thus, we investigated: (1) whether appropriate soil quality indicators (SQIs) could be identified in soils of Great Britain, (2) whether conventional soil classification or aggregate vegetation classes (AVCs) could predict SQIs and (3) to what extent do soil types and/ or AVCs act as major regulators of SQIs. Factor analysis was used to group 20 soil attributes into six SQI which were named as; soil organic matter (SOM), dissolved organic matter (DOM), soluble N, reduced N, microbial biomass, DOM humification (DOMH). SOM was identified as the most important SQI in the discrimination of both soil types and AVCs. Soil attributes constituting highly to the SOM factor were, microbial quotient and bulk density. The SOM indicator discriminated three soil type groupings and four aggregate vegetation class groupings. Among the soil types, only the peat soils were discriminated from other groups while among the AVCs only the heath and bog classes were isolated from others. However, the peat soil and heath and bog AVC were the only groups that were distinctly discriminated from other groups. All other groups heavily overlapped with one another, making it practically impossible to define reference values for each soil type or AVC. The two-way ANOVA showed that the AVCs were a better regulator of the SQIs than the soil types. We conclude that conventionally classified soil types cannot predict the SQIs defined from large areas with differing climatic and edaphic factors. Localised areas with similar climatic and topoedaphic factors may hold promise for the definition of SQI that may predict the soil types or AVCs

The effect of paramedic position on external chest compression quality: a simulation study

Out-of-hospital cardiac arrest (OHCA) is a globally important public health issue that continues to be a significant cause of premature death. The incidence of OHCA treated by Emergency Medical Services (EMS) is around 50 to 55/100,000 per person-years across the US, Canada, Australia and New Zealand. There is significant disparity in the rates of survival to hospital discharge from OHCA. For OHCA treated by EMS this rate can vary as much as 1% to 31%. In order to improve outcomes for cardiac arrests the International Liaison Committee on Resuscitation (ILCOR) aims to integrate resuscitation science with real world clinical practice. ILCOR states there is a need to develop a culture of high quality resuscitation using a quality improvement approach. Survival from cardiac arrest is a complex issue with many stakeholders that form the basis of a system of care. ILCOR proposes that individual performance needs to be evaluated so that participants within the system of care are informed and can therefore effectively intervene to improve care Paramedics are the primary treatment providers for OHCA. Recently the resuscitation guidelines, which paramedics use in their practice, have emphasised the performance of quality chest compressions. With this in mind this thesis sought to investigate whether the position of the paramedic performing chest compressions, either from-the-side (FTS) or over-the-head (OTH), influenced the quality of cardiopulmonary resuscitation (CPR). A review literature identified only a few small studies in which OTH CPR was investigated over short durations. There was heterogeneity in the study design, types of participants and quality metrics measured with inconsistencies in the results across the studies. All of the studies identified in the review were manikin studies that used manikin-based technology, such as the Laerdal Skill Reporter (LSR), to measure the quality of CPR. Subsequent to these studies defibrillator technology has evolved and now devices that can measure CPR quality have been integrated into the defibrillator, an example of which is Q-CPR associated with the MRx defibrillator. Such devices enable measurement of CPR quality in both manikin and human studies. The first study (Chapter 3) investigated if the new defibrillator technology could be used to measure CPR quality in a manikin study. This study compared the measurement of CPR quality metrics simultaneously using LSR and Q-CPR, for chest compression performed OTH and FTS. The principle finding of this study was that there is no significant difference in the majority of chest compression quality metrics measured between the LSR and the Q-CPR devices. However, there were significant differences in the measurement of duty cycle and also the depth of compressions between the two devices. The mean difference in the depth of compression was observed to increase with an increasing incidence of leaning. The conclusion was that Q-CPR is a suitable alternative to LSR for measurement of the CPR quality and thus it was used in the main study. The main study compared OTH and FTS CPR quality (performed by 30 paramedics) during two simulated cardiac arrest scenarios, each of approximately 25 minutes duration. There was no significant difference in mean CPR quality between compressions performed OTH or FTS for all metrics measured. We concluded that for two rescuer CPR the composite technique, where the paramedic that is positioned at the head of the manikin performs OTH CPR, is an effective alternative to the traditional method of only performing CPR FTS