Evaluation of the solute transport characteristics of surcharged manholes using a RANS solution

Urban drainage networks contain a large number of structures; the most common of which is a manhole. Previous studies investigating solute transport through manholes identified a threshold level of surcharge at which the hydraulic conditions in the manholes sharply altered. At high levels of surcharge, a dead zone formed above the main jet, potentially retaining solute for later discharge. This phenomenon could have significant impacts on the results obtained from 1D urban drainage network models which only consider pure advection. Previous research (including other CFD based studies) concentrated on steady flow conditions through these structures which are not thought to be representative of the dynamic flow conditions experienced in practice. During large storm events, the capacity of combined sewer networks may be exceeded. This leads to the discharge of untreated sewage to receiving watercourses. Discharges such as these are governed by legislation and, therefore, an understanding of pollutant transfer through urban drainage networks is required. Using existing laboratory and Computational Fluid Dynamics (CFD) data, this study produced a primary and secondary validated methodology for meshing and modelling manholes using CFD. This was then extended to free-surface multiphase modelling allowing for more realistic unsteady conditions to be considered. This included an in-depth comparison of suitable turbulence models and solute-modelling options. It was found that, whilst it was possible to model multiphase free-surface flow within such a structure, it was unnecessarily computationally expensive as temporal changes in the flow field are rapid when compared with a practical time-step for use with 1D models. The validated modelling methodology was then used to recreate the original study that identified the hydraulic threshold. This included a selection of manholes with a range of inlet to manhole diameter ratios. However, this was extended further to include manholes with a ratio less than five (commonly found in UK sewer systems). It was shown that the hydraulic threshold broke down below this limit, removing the need for this to be modelled in 1D systems.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Exploring low-degree nodes first accelerates network exploration

We consider information diffusion on Web-like networks and how random walks can simulate it. A well-studied problem in this domain is Partial Cover Time, i.e., the calculation of the expected number of steps a random walker needs to visit a given fraction of the nodes of the network. We notice that some of the fastest solutions in fact require that nodes have perfect knowledge of the degree distribution of their neighbors, which in many practical cases is not obtainable, e.g., for privacy reasons. We thus introduce a version of the Cover problem that considers such limitations: Partial Cover Time with Budget. The budget is a limit on the number of neighbors that can be inspected for their degree; we have adapted optimal random walks strategies from the literature to operate under such budget. Our solution is called Min-degree (MD) and, essentially, it biases random walkers towards visiting peripheral areas of the network first. Extensive benchmarking on six real datasets proves that the---perhaps counter-intuitive strategy---MD strategy is in fact highly competitive wrt. state-of-the-art algorithms for cover

Exploring the scope and utility of dynamic covalent chemistry within polymeric nanoparticles

Dynamic covalent chemistry encompasses reversible bond forming reactions which proceed under equilibrium control, where the position of the equilibria are sensitive to changes in environment, and which are often able to undergo component exchange. These virtues provide polymeric nanoparticles incorporating dynamic covalent bonds with the ability to reconfigure or change their structural properties in response to stimuli. In Chapter 1 we critically discuss and evaluate the current state of the art whereby polymer chemists have exploited dynamic covalent bonds within responsive and adaptive polymeric nanoparticles. Chapter 2 describes the synthesis and study of a chemoresponsive polymeric micelle. In this work, aldehyde and alkoxyamine endfunctionalized polymers are shown to link together through a single oxime bond and then self-assemble into micellar aggregates. The chemoresponsive nature of these micellar aggregates is expressed when their disassembly is triggered through the addition of a small molecule alkoxyamine. Chemoresponsive core cross-linked star and nanogel nanoparticles which contain multiple imine cross-links are presented in Chapter 3. These imine linkages are utilized to facilitate the self-assembly process of the nanoparticles, which display chemoresponsive disassembly upon the addition of a small molecule amine. Chapter 4 describes the preparation of core cross-linked star polymers which are both pH-responsive and thermoresponsive. The pH-responsive nature is imparted through the pH-responsiveness of multiple imine linkages, and their thermoresponsive nature arises on account of the thermoresponsive polymer chains contained within their cores. In Chapter 5 nanoparticles possessing pH-responsive imine and redox-responsive disulfide cross-links have been developed where the simultaneous application of both low pH and a reducing agent is required to trigger their disassembly. It is shown that the application of either low pH or a reducing agent does not trigger disassembly. The research presented throughout this dissertation confirms the great potential of dynamic covalent chemistry in the development of stimuliresponsive polymeric nanoparticles.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Critical rationalism and macrosociology of globalisation

This thesis employs Critical Rationalism—an inter-subjective theory of rationality originated in Karl Popper’s conjectural theory of knowledge— in order to develop a new macrosociology of globalisation. It describes contemporary globalisation as the formation of a liberal globality through which the centrality of the Hobbesian struggle for political power has been superseded with the Lockean competition for economic interests. But the thesis argues that liberal globalisation suffers from fundamental societal deficits due to a global organisation of people based on economic competition rather than rational dialogue and social cooperation. The central question of thesis therefore is that ‘how emerging utilitarian-based liberal globality can be transformed into a global society of free and equal citizens?’ The thesis argues that people’s potential access to critical rationality enables them to agree upon one set of globally shared values concerning the equality of people and people-centric global institutions, which are required for creating a global society of free and equal citizens. Through its macrosociological analysis the thesis addresses the question of how such a system of globally shared values can operate as the cultural driving force of a radical global institutional change from the Lockean logic of economic competition to the Kantian logic of dialogue and social cooperation. The thesis concludes that intellectuals can employ the ideal-type of an open global society of free and equal persons in order to persuade global social movements to work for realising such a fundamental global institutional change towards a just and free global society.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Factors Associated with Adherence to the Mediterranean Diet among Adolescents Living in Sicily, Southern Italy

The present study aimed to examine the factors associated with increased Mediterranean diet (MD) adherence among a sample of Italian adolescents. A cross-sectional survey was conducted on 1135 students (13–16 years) attending 13 secondary schools of Sicily, southern Italy. Validated instruments were used for dietary assessment and the KIDMED score to assess adolescents’ adherence to the MD. A higher adherence to the MD was associated with high socioeconomic status (Odds Ratio [OR] 1.53, 95% Confidence Interval [CI]: 1.03–2.26) and high physical activity (OR 1.19, 95% CI: 1.02–1.70), whereas lower adherence was associated with living in an urban environment (OR 0.65, 95% CI: 0.44–0.97) and being obese (OR 0.59, 95% CI: 0.37–0.94). The adolescents’ KIDMED scores were inversely associated with adolescents’ intake of sweets, fast foods, fried foods, and sugary drinks, and directly with fruit, vegetables, pasta, fish, and cheese intakes. Urban-living adolescents were less likely to eat fruit and more prone to consume meat, sugary drinks, and fast food than rural-living adolescents. The latter were more likely to eat sweets and snacks. A general poor quality of food consumption in Italian adolescents away from the MD was reported, especially among those living in urban areas

Observation of Dirac plasmons in a topological insulator

Plasmons are the quantized collective oscillations of electrons in metals and doped semiconductors. The plasmons of ordinary, massive electrons are since a long time basic ingredients of research in plasmonics and in optical metamaterials. Plasmons of massless Dirac electrons were instead recently observed in a purely two-dimensional electron system (2DEG)like graphene, and their properties are promising for new tunable plasmonic metamaterials in the terahertz and the mid-infrared frequency range. Dirac quasi-particles are known to exist also in the two-dimensional electron gas which forms at the surface of topological insulators due to a strong spin-orbit interaction. Therefore,one may look for their collective excitations by using infrared spectroscopy. Here we first report evidence of plasmonic excitations in a topological insulator (Bi2Se3), that was engineered in thin micro-ribbon arrays of different width W and period 2W to select suitable values of the plasmon wavevector k. Their lineshape was found to be extremely robust vs. temperature between 6 and 300 K, as one may expect for the excitations of topological carriers. Moreover, by changing W and measuring in the terahertz range the plasmonic frequency vP vs. k we could show, without using any fitting parameter, that the dispersion curve is in quantitative agreement with that predicted for Dirac plasmons.Comment: 11 pages, 3 figures, published in Nature Nanotechnology (2013

Coexistence and conviviality in multi-faith, multi-ethnic Burgazadasi, the princes' islands of Istanbul

This thesis aims to provide an understanding of the existing cultural plurality and diversity in Burgazadası, within a post-Ottoman and homogenising context in Turkey. Most of the scholars working on conflict resolution and peace projects in the Balkans and the Middle East have attempted to analyse cultural plurality with the concept of “coexistence”. “Coexistence” as a concept presupposes the pre-existing categories of ethnicity, class and religion (i.e. coexistence between Israelis and Palestinians; Greek and Turkish Cypriots; Serbs, Croats and Bosnians). In this thesis, I demonstrate the inadequacy of the concept of “coexistence” and propose a “conviviality” approach to explore cultural pluralism. In the post-Ottoman, Turkish context in Burgaz, “coexistence” can be used when describing the homogenisation process, the construction and perception of categorisations of differences, the crystallisation of ethnic and religious identities and ruptures to cultural pluralism; but it is deficient in describing the continuity of cultural pluralism and what is shared between the members of the community in Burgaz. By contrast, “conviviality” provides an understanding of the continuity of cultural pluralism in Burgaz, the changes in sociality patterns, shared ways of living, the diversity and differentiations within “different groups”, the islanders' sense of belonging in Burgaz, their appreciation of diversity and acts of solidarity at the times of crisis. I argue that the homogenisation process in Turkey brought ruptures in cultural pluralism in Turkey, and changed the demographics in Burgaz; however the homogenisation process did not rupture the conviviality on the island and Burgazian identity which embraces all types of diversities of its inhabitants. At times of crisis, like in September 1955 riots, Burgaz islanders emphasised their shared Burgaz identity which overrode religious, class and ethnic differencesEThOS - Electronic Theses Online ServiceGBUnited Kingdo

Mechanical thrombectomy in patients with proximal occlusions and low NIHSS: Results from a large prospective registry

Background: Mechanical thrombectomy is now standard of care for treatment of acute ischemic stroke secondary to large vessel occlusion in the setting of high NIHSS. We analysed a large nationwide registry focusing on patients with large vessel occlusion and low NIHSS on admission to evaluate the efficacy and safety of thrombectomy in this patient population Methods: 2826 patients treated with mechanical thrombectomy were included in a multicentre registry from January 1, 2011 to December 31, 2015. We included patients with large vessel occlusion and NIHSS ≤ 6 on admission. Baseline characteristics, imaging, clinical outcome, procedure adverse events and positive and negative outcome predictors were analysed. Results: 134 patients were included. 90/134 had an anterior circulation and 44 a posterior circulation stroke. One patient died before treatment. Successful revascularization (mTICI 2b-3) was achieved in 73.7% (98/133) of the patients. Intraprocedural adverse event was observed in 3% (4/133) of cases. Symptomatic intracranial haemorrhage rate was 5.3% (7/133). At three months, 70.9% (95/134) of the patients had mRS score 0-2, 15.7% (21/134) mRS 3-5 and 13.4% (18/134) mRS 6. Age and successful recanalization were significant predictors of a good clinical outcome on both univariate (p= 0.005 and p=0.007) and multivariable (p=0.0018 and p=0.009 [nat log]) analysis. Absence of vessel recanalization and symptomatic intracranial hemorrhage were independent predictors of poor outcome (p=0.021). Conclusions: Our study suggests that patients with large vessel occlusion and low NIHSS score on admission can benefit from mechanical thrombectomy. Randomized trials are warranted

Melting of magnetic order in NaOsO₃ by femtosecond laser pulses

NaOsO3 has recently attracted significant attention for the strong coupling between its electronic band structure and magnetic ordering. Here, we used time-resolved magnetic x-ray diffraction to determine the timescale of the photoinduced antiferromagnetic dynamics in NaOsO3. Our measurements are consistent with a sub-100 fs melting of the antiferromagnetic long-range order that occurs significantly faster than the lattice dynamics as monitored by the transient change in intensity of selected Bragg structural reflections, which instead show a decrease of intensity on a timescale of several ps