UCL University College London Eprints
UCL Eprints collects the work of UCL researchers and makes it freely available over the web, helping the worldwide scholarly community to discover UCL research. Institutional repositories like UCL Eprints complement the traditional academic publishing and scholarly communications processes. They raise the visibility of research and help to maximise its impact. UCL researchers are encouraged to deposit a copy of each journal article, conference paper, working paper, and any other research output, in the UCL Eprints at the earliest opportunity, ensuring that their research reaches as wide an audience as possible.
Mostrando recursos 141 - 160 de 368,555
Essays on econometric models of discrete choice for vertically differentiated alternatives in oligopoly markets - Aristodemou, E
This thesis studies discrete choice demand models for vertically differentiated alternatives
in oligopoly market settings and focuses on identification in discrete choice
models motivated by demand. A cross-sectional discrete choice demand model is developed,
where individuals choose the product that maximizes their utility, from a set
of vertically differentiated alternatives offered by a set of horizontally differentiated
brands. This allows the model to capture important features of individual substitution
patterns when both kinds of differentiation are present. The unordered-ordered discrete
nature of the two dimensions of the individual decision problem typically results
in set identification of model parameters. The cross-sectional model is then extended
to cover panel data settings,...
A commentary on the fragments of the iambic poet Hipponax - Alexandrou, M
The thesis fills a surprising gap in Classical scholarship by providing the first philological and literary commentary in English on the most substantial fragments of the 6th century BCE iambic poet Hipponax. The project is a timely contribution to the recent developments in the field of study of iambos and Greek Lyric more generally, as well as the study of fragmentary poetry and literature. The text and apparatus provided are based on West’s edition of the fragments (Iambi et Elegi Graeci ante Alexandrum Cantati, 2nd edition, vol.1 (1989-92)) with divergences indicated. The fragments treated are drawn both from secondary sources...
Ship Operational Efficiency: Performance Models and Uncertainty Analysis - Aldous, LG
There are increasing economic and environmental incentives for ship owners and operators to develop tools to optimise operational decisions, particularly with the aim of reducing fuel consumption and/or maximising profit. Examples include real time operational optimisation, maintenance triggers and evaluating technological interventions. Performance monitoring is also relevant to fault analysis, charter party analysis, vessel benchmarking and to better inform policy decisions. The ship onboard systems and systems in which they operate are complex and it’s common for data modelling and analysis techniques to be employed to help extract trends. All datasets and modelling procedures have an inherent uncertainty and to...
Discontinuities in mathematical modelling: origin, detection and resolution - Alsoudani, T
When modelling a chemical process, a modeller is usually required to handle a wide variations in time and/or length scales of its underlying differential equations by eliminating either the faster or slower dynamics. When compelled to deal with both and simultaneously simplify model structure, he/she is sometimes forced to make decisions that render the resulting model discontinuous. Discontinuities between adjacent regions, described by different equation sets, cause difficulties for ODE solvers. Two types exist for handling discontinuities in ODEs. Type I handles a discontinuity from the ODE solver side without paying any attention to the ODE model. This resolution to...
Non-existence of competitive equilibria with dynamically inconsistent preferences - Gabrieli, T; Ghosal, S
This paper shows the robust non-existence of competitive equilibria even in a simple three period representative agent economy with dynamically inconsistent preferences. We distinguish between a sophisticated and naive representative agent. Even when underlying preferences are monotone and convex, at given prices, we show by example that the induced preference of the sophisticated representative agent over choices in first-period markets is both non-convex and satiated. Even allowing for negative prices, the market-clearing allocation is not contained in the convex hull of demand. Finally, with a naive representative agent, we show that perfect foresight is incompatible with market clearing and individual...
Early laparoscopic cholecystectomy appears better than delayed laparoscopic cholecystectomy for patients with acute cholecystitis - Gurusamy, K
Commentary on: Wu XD, Tian X, Liu MM, et al. Meta-analysis
comparing early versus delayed laparoscopic cholecystectomy for
acute cholecystitis. Br J Surg 2015;102:1302–13.
Acute cholecystitis, also known as inflammation of the gallbladder, can be
broadly classified as either acute calculous cholecystitis (caused by gallstones)
1 or acute acalculous cholecystitis (following serious illness such as
systemic sepsis or major surgery).2 Cholecystectomy is mainly indicated in
acute calculous cholecystitis,1 while percutaneous cholecystostomy is used
as the definitive treatment in the absence of gallstones for patients with
acalculous cholecystitis.2 The timing of cholecystectomy (which is usually
performed laparoscopically)1 is a matter of significant controversy in
patients with acute calculous cholecystitis. While delayed laparoscopic
French imperial projects in Mexico (1820-1867) - Shawcross, ETM
The standard narrative of nineteenth-century imperialism in Latin America is one of US expansion and British informal influence. However, it was France, not Britain, which made the most concerted effort to counter US power through Louis-Napoléon’s creation of an empire in Mexico under the Habsburg Archduke Maximilian. Despite its significance to French and Mexican history, this intervention is invariably described as an “illusion”, an “adventure” or a “mirage”. This thesis answers the question why some Mexicans believed that the survival of the nation itself depended upon French intervention, and why France sought to impose an informal-imperial model on Mexico. It...
Provisional Realities: Live Art 1951-2015 - Maidment, IM
This thesis reframes the history of live art as a mode of simultaneous production, exhibition and reception that emerged as an aesthetic form of new significance post-1945. In an attempt to complicate the existing terrain of interpretation, I present the history of live art as a mode of representation, and method of making, rooted not just in space but, importantly, in time. Over five chapters I trace a trans-historical dialogue between the neo-avant-garde and contemporary live art since the turn of the millennium. The thesis is structured around four temporal framings: the vernissage; the night; the stage, and the museum;...
The effectiveness of changes in street layout and design for reducing barriers to walking - Anciaes, PR; Jones, PM
This study analyses the effectiveness of two types of interventions to reduce built environment barriers to walking: changing the layout of the local street network (by increasing the density and connectivity of the links available to pedestrians) and redesigning a busy road (by adding crossing facilities, reducing speed limit, or reallocating road space to pedestrians). The analysis focuses on a residential neighbourhood in London which is being extensively redeveloped. The anticipated effects of the interventions are assessed in terms of the distance, delay, safety, and environmental quality of walking trips from residences to public transport nodes. The study also addresses...
Rebranding the Neoliberal City: Urban Nature as Spectacle, Medium, and Agency - Langhorst, Joern
Post-industrial sites are frequently seen as aesthetically sublime, considered as iconic reminders of an ongoing de-industrialization, and interpreted as symbols of the failure of the industrial age. Simultaneously they are also locations to re-imagine, reinvent and recover landscapes as agents for essential, sustainable, and environmentally-just urban transformations. The most visible discourses on post-industrial urban sites emphasize issues of environmental justice, pollution mitigation, adaptive reuse, and, in the context of urban redevelopment and renewal, benefits and performances based on ecological functions and processes. On the one hand, current concepts such as “landscape urbanism”, “sustainable urbanism” and “ecological urbanism” (as conceptual and...
Dilapidated Dwelling - Keiller, Patrick
Where I live, there seem to be two kinds of space. There is new space, in which none of the buildings are more than about ten years old, and there is old space, in which most of the buildings are at least twenty years old, a lot of them over ninety years old, and all are more or less dilapidated.
Patrick Keiller begins his 1998 essay The Dilapidated Dwelling with a concise and simple description of the issues he raises in both the essay and the film to which it relates, The Dilapidated Dwelling, 2000. In both film and word...
Porosity: Networking Cities for a Changing Climate - Napawan, N. Claire; Snyder, Brett
On October 28th 2013 Hurricane Sandy hit land on the East Coast of the United States. The deadliest storm to hit the country since 2005 it caused tens of billions of dollars in damage, destroyed thousands of homes, left millions without electric service, and caused 117 deaths in the United States, including 53 in New York, making Sandy the most life costly hurricane to hit the United States mainland since Hurricane Katrina. In all an estimated 186 people were killed across the United States, the Caribbean, and Canada. In the immediate aftermath of the storm not only did the emergency...
Framing the Real: Lefèbvre and NeoRealist Cinematic Space as Practice - Brancaleone, David
In 1945 Roberto Rossellini's Neo-realist Rome, Open City set in motion an approach to cinema and its representation of real life – and by extension real spaces – that was to have international significance in film theory and practice. However, the re-use of the real spaces of the city, and elsewhere, as film sets in Neo-realist film offered (and offers) more than an influential aesthetic and set of cinematic theories. Through Neo-realism, it can be argued that we gain access to a cinematic relational and multidimensional space that is not made from built sets, but by filming the built environment....
Gender, Public Space and Resistance - Baydar, Gülsüm
On May 27, 2013 at 11:30 pm bulldozers drove into Gezi, a central park in Taksim, Istanbul, to uproot five trees in preparation for future construction. Plans for the redevelopment had been announced two years before by the Prime Minister, Recep Tayyip Erdogan, and in response, two local activist groups had been formed: 'Taksim Solidarity' and the 'Society for the Preservation and Beautification of Gezi Park'. Founded to to publicise the historical status of the park and protect what remains a symbolically important site - and one of the few recreation areas in the central area of Istanbul - members...
Hazing Iran: Satellite Imagery, Human Rights, and City as Camp - Zhang, Amy
As perhaps most obviously evidenced in the political maneuverings that led up to the second Gulf War in 2003, the use of satellite imagery to document spatial terrain is often, and almost instantly, politicized. In the two images presented here, this politicization takes on a two-way relationship and is open to contrasting and inevitably dualistic readings. One way of describing their relationship is as "Target" and "Aftermath". On the left, we have an image of the nuclear plant near the Iranian city of Qom, annotated in this version by the US security services to highlight 'suspicious' activity said to evidence...
Roles of the RNAi pathway in making telomere-free chromosome ends - Begnis, M
The discovery of a new mode of telomerase minus survival, ‘HAATI’, shook the dogma that canonical telomeres are essential to maintain linear chromosomes (Jain et al., 2010). In HAATI cells, telomeric sequences are superseded by blocks of generic heterochromatin, which jump to all chromosome ends and acquire the ability to protect them from fusions and degradation. While they lack of detectable telomeric repeats, these newly acquired termini recruit the canonical end-protection factor Pot1 and guarantee end protection. The amplified elements in HAATI are repetitive sequences associated with heterochromatin. Most commonly, the ribosomal DNA (rDNA) is the preferred substrate for this...
Bayesian statistical modelling of genetic sequence evolution - Angelis, K
Bayesian statistics has been at the heart of phylogenetic inference over the last decade, particularly after the development of powerful programs that implement efficient Markov chain Monte Carlo algorithms, allowing inference from multi-parametric problems in realistic time frames. In this thesis we develop and test Bayesian methods to analyse molecular sequence data to address important biological questions. First, we review some fundamental aspects of Bayesian inference and highlight current Bayesian applications in molecular evolution with particular focus in studying natural selection and estimating species divergence times. Then, we develop a new Bayesian method to estimate the nonsynonymous/synonymous rate ratio and...