This dissertation examines aspects of both the consumer (the "give") and the server (the "take") sides of restaurant tipping. On the consumer side, I address both why, and how much, people tip in restaurants. I also examine a policy issue related to the recent Supreme Court decision in United States v. Fior d'Italia. These issues are addressed via a combination of theoretical, empirical, and experimental analysis. On the server side, I use survey data collected from several restaurants to address the issue of labor market discrimination based on beauty. Specifically, do more attractive servers earn higher tips than less attractive servers? I argue that a tipping data set offers several advantages over data sets used in previous studies of the beauty wage gap. This dissertation was funded by a National Science Foundation Dissertation Enhancement Grant (NSF #427347). / Ph. D.

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‘Tipping points’ in the climate system are characterised by a nonlinear response to gradual forcing, and may have severe and wide-ranging impacts. One of the best ways to identify and potentially predict threshold behaviour in the climate system is through analysis of palaeoclimate records. It has been suggested that early warning signals occur on the approach to a tipping point, generated from characteristic fluctuations in a time series as a system loses stability. Although early warning signals have been found in climate models and high-resolution marine and ice core palaeodata, studies from terrestrial records are lacking. In this study, a number of Pleistocene terrestrial records were selected to represent a range of regions strongly influenced by different climate modes which are thought to be capable of displaying threshold behaviour. These records included lake sediments from the North Atlantic, tree-rings from the South Pacific, a Chinese speleothem and were complemented by a new Greenland ice core chronology. Recently developed methods to detect signals of ‘critical slowing down’, ‘flickering’, and stability changes on the approach to a tipping point were utilised. Specific methodological issues arising from analysing palaeoclimate data were also investigated using a simple bifurcation model. A number of key criteria were found to be necessary for the reliable identification of early warning signals in palaeoclimate records, most crucially, the need for a low-noise record of sufficient data length, resolution and accuracy. Analysis of a Chinese speleothem identified the East Asian Summer Monsoon as an important climate ‘tipping element’, which may display a cascade of impacts. However, in some cases where early warning signals may fail, a deeper understanding of the underlying system dynamics is required to inform the development of more robust system-specific indicators. This was exemplified by the analysis of an abrupt, centennial-duration shutdown recorded during the Younger Dryas Chronozone in New Zealand, which demonstrated no slowing down, consistent with a freshwater pulse into the Southern Ocean. This study demonstrates that time series precursors from palaeoclimate archives provide a means of useful forewarning of many potential climate tipping points.

Rate-induced transitions have recently emerged as an identifiable type of instability of attractors in nonautonomous dynamical systems. In most studies so far, these attractors can be associated with equilibria of an autonomous limiting system, but this is not necessarily the case. For a specific class of systems with a parameter shift between two autonomous systems, we consider how the breakdown of the quasistatic approximation for attractors can lead to rate-induced transitions, where nonautonomous instability can be characterised in terms of a critical rate of the parameter shift. We find a number of new phenomena for non-equilibrium attractors: weak tracking where the pullback attractor of the system limits to a proper subset of the attractor of the future limit system, partial tipping where certain phases of the pullback attractor tip and others track the quasistatic attractor, em invisible tipping where the critical rate of partial tipping is isolated and separates two parameter regions where the system exhibits end-point tracking. For a model parameter shift system with periodic attractors, we characterise thresholds of rate-induced tipping to partial and total tipping. We show these thresholds can be found in terms of certain periodic-to-periodic and periodic-to-equilibrium connections that we determine using Lin's method for an augmented system. Considering weak tracking for a nonautonomous Rossler system, we show that there are infinitely many critical rates at which a pullback attracting solution of the system tracks an embedded unstable periodic orbit of the future chaotic attractor.

The term ‘tipping event’ is used to describe a certain class of phenomena as observed in many different fields of science. It refers to an event where a gradual change of external forcing causes a sudden, large, often unwanted, transition to the state of the system. Some examples of known tipping events in science include: Arctic sea ice melting (climate), epileptic seizures (biology), collapse of ecosystems and populations (ecology) and market crashes (finance). Three mathematical mechanisms for tipping events have been proposed in the literature: bifurcation-, noise- or rate-induced tipping. Recent research has focused on developing early-warning indicators to potentially offer forewarning, which can extract from output time series whether the external forcing approaches a critical level at which tipping occurs. Two commonly used early-warning indicators are an increase of autocorrelation and variance in the time series data for the system’s output. The theory behind the presence of these indicators is the loss of stability of the system’s current state known as ‘critical slowing down’ for the approach of a bifurcation-induced tipping. Rate-induced tipping occurs when the external forcing reaches a critical rate instead of level. For rate-induced tipping there is no loss of stability of the system’s current state and therefore it is not clear if the early-warning indicators should exist. In this thesis we investigate the presence of early-warning indicators for models that show rate-induced tipping with additive noise. We also explore a technique for determining the most likely time of tipping using optimal paths for escape. Research has mainly focussed on testing the early-warning indicators for examples of known tipping events in the past. The ultimate aim of early-warning indicators would be to have the ability to predict future tipping events. Using the early-warning indicators in isolation is susceptible to incurring false alarms and missed alarms. We present a method for approximating the probability of experiencing rate-induced tipping with noise for slow to moderate drift speeds.

This thesis examines how early warning signals perform when tested on climate systems thought to exhibit future tipping point behaviour. A tipping point in a dynamical system is a large and sudden change to the state of the system, usually caused by changes in external forcing. This is due to the state the system occupies becoming unstable, causing the system to settle to a new stable state. In many cases, there is a degree of irreversibility once the tipping point has been passed, preventing the system from reverting back to its original state without a large reversal in forcing. Passing tipping points in climate systems, such as the Amazon rainforest or the Atlantic Meridional Overturning Circulation, is particularly dangerous as the effects of this will be globally felt. Fortunately there is potential for early warning signals, designed to warn that the system is approaching a tipping point. Generally, these early warning signals are based on analysis of the time series of the system, such as searching for ‘critical slowing down’, usually estimated by an increasing lag-1 autocorrelation (AR(1)). The idea here is that as a system’s state becomes less stable, it will start to react more sluggishly to short term perturbations. While early warning signals have been tested extensively in simple models and on palaeoclimate data, there has been very little research into how these behave in complex models and observed data. Here, early warning signals are tested on climate systems that show tipping point behaviour in general circulation models. Furthermore, it examines why early warning signals might fail in certain cases and provides prospect for more ‘system specific indicators’ based on properties of individual tipping elements. The thesis also examines how slowing down in a system might affect ecosystems that are being driven by it.

A wide range of ecological communities ranging from polar terrestrial to tropical marine environments are affectedby global climate change. Over the last century, atmospheric temperature has increased by an average of 0. 60 C andis expected to rise by 1.1- 6.40C over the next 100 years. This rising temperature has increased the intensity andfrequency of weather extremes due to which a large number of species are facing risk of extinction. Studies haveshown that species existing on lower latitude are more sensitive to temperature variability compared to speciesexisting on higher latitude but temperature is increasing rapidly in higher latitude compare to lower latitude. Thisuneven distribution of temperature sensitive species and warming rate has highlighted the need for combined studiesof temperature variability and sensitiveness of species to predict how the ecosystems will respond to increasinglyvariable climate. Using a generalized Rosenzweig-MacArthur model, I explored how temperature variability andsensitivity of species will affect the extinction risks of species and how the connectance and species-richness ofecological communities will govern this response. This study showed that the risk of extinction of species mostlydepends on their sensitivity to temperature deviation from the optimum value and level of temperature variability.Among these two, sensitivity of species to temperature deviation was most prominent factor affecting extinction risk.In this study, connectance did not show any effect on mean extinction risk and time taken by a certain proportion ofspecies to reach pre-defined extinction thresholds. But, species-richness showed some effect on mean extinction riskof species. It was found that risk of extinction of species in species-rich communities was higher compared tospecies-poor communities. Species-rich communities also took shorter time before they lost 1/6 of the species. Thepresent study also suggests a possible tipping point due to increasing temperature variability in near future. In furtherstudies, different sensitivity of species at different trophic levels and the possible evolution of sensitivity of speciesshould also be consider while predicting how ecological communities will respond to changing climate in the longrun.

In the era of intense pressures on water resources, the loss of groundwater by increased seawater intrusion (SWI), driven by climate, sea level and landscape changes, may be critical for many people living in commonly populous coastal regions. Analytical solutions have been derived here for interface flow in coastal aquifers, which allow for simple quantification of SWI under extended conditions from previously available such solutions and are suitable for first-order regional vulnerability assessment and mapping of the implications of climate- and landscape-driven change scenarios and related comparisons across various coastal world regions. Specifically, the derived solutions can account for the hydraulically significant aquifer bed slope in quantifying the toe location of a fresh-seawater sharp interface in the present assessments of vulnerability and safe exploitation of regional coastal groundwater.  Results show high nonlinearity of SWI responses to hydro-climatic and groundwater pumping changes on the landside and sea level rise on the marine side, implying thresholds, or tipping points, which, if crossed, may lead abruptly to major SWI of the aquifer. Critical limits of coastal groundwater change and exploitation have been identified and quantified in direct relation to prevailing local-regional conditions and stresses, defining a safe operating space for the human use of coastal groundwater. Generally, to control SWI, coastal aquifer management should focus on adequate fresh groundwater discharge to the sea, rather than on maintaining a certain hydraulic head at some aquifer location. First-order vulnerability assessments for regional Mediterranean aquifers of the Nile Delta Aquifer, the Israel Coastal Aquifer  and the Cyprus Akrotiri Aquifer show that in particular the first is seriously threatened by advancing seawater. Safe operating spaces determined for the latter two show that the current pumping schemes are not sustainable under declining recharge. / <p>The thesis was founded by two research programmes: NEO private-academic sector partnership and Ekoklim, a strategic governmental funding through Stockholm University</p><p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p><p> </p>

As many theorists have pointed out, queer history is often erased within traditional, heteronormative historiography. Consequently, historians cannot recount the gay and lesbian past by conventional techniques of evidence and documentation. Instead they recuperate and reinvent queer history using strategies normally associated with the writing of fiction. This thesis examines three works of late twentieth century lesbian historical fiction that rewrite the past in order to render visible queer intimacy, sexuality, and desire. Jeanette Winterson's The Passion (1987), Sarah Waters' Tipping the Velvet (1998), and Helen Humphreys' Leaving Earth (1997) employ spectacularly visible lesbian heroines who symbolically reverse lesbian invisibility in mainstream historical narratives by displaying themselves as public figures or stage performers. There are ongoing debates in contemporary queer theory and historiography about the extent to which it is politically useful to privilege highly visible individuals when recovering the marginalized gay and lesbian past. Winterson's, Waters', and Humphreys' novels enact this debate, and exemplify a trend in contemporary lesbian historical fiction in which lesbian heroines are empowered by their ability to control their own visibility and to ensure the perpetuation of their history.

Made available in DSpace on 2014-08-20T13:20:49Z (GMT). No. of bitstreams: 1 Amanda_Costa_Silva_Dissertacao.pdf: 4332100 bytes, checksum: e15874c3653ae555a6677b26dbd71069 (MD5) Previous issue date: 2013-03-27 / The central objective of this essay was to reflect about the Cine-Theatro Independência s process of tipping, at Santa Maria (RS), discussing the conflicts related to heritage preservation and memorials choices. This place was inaugurated in 1922 in the central square of the city. Throughout more than 70 years, it staged performances, meetings and reunions gatherings, besides daily views of movies. Although Santa Maria have other great representation spaces for the cultural scene of the city, Cine Independência was the only movie theater in town that went through a process of tipping. This process, however, went so nebulous and seemingly confused. Currently, the space is mischaracterized and houses the Popular Shopping of Santa Maria. Therefore, this study aimed to identify, from the site's history and the process of tipping, elements that were crucial to the well reached the current situation, performing a reflection on the conflicts that underlie this process. For this, a literature has developed in relation the city's history, its cultu ral spaces and Cine Independência, contextualizing with other major cities of the state, as preservationists regarding public policies and memory and heritage concepts. In addition, it was searched documentation linked to this process of tipping, as well, along with the city archives, images and articles published in journals. Finally, if conducted an interview with former mayor of Santa Maria, seeking thus to better understand how this process took place and the constitution of the Popular Shopping of Santa Maria / O objetivo central dessa pesquisa foi refletir sobre o processo de tombamento do prédio que abrigou o Cine-Theatro Independência, em Santa Maria (RS), debatendo os conflitos referentes à preservação do patrimônio e às escolhas memoriais. O espaço foi inaugurado em 1922, na praça central da cidade. Ao longo de seus mais de 70 anos, foi palco de apresentações artísticas, encontros e reuniões sociais, além das exibições diárias de filmes. Apesar de Santa Maria possuir outros espaços de grande representatividade para o cenário cultural do município, o Cine Independência foi o único cine-teatro da cidade que passou por um processo de tombamento. Esse processo, entretanto, transcorreu de forma nebulosa e aparentemente confusa. Atualmente, o espaço está descaracterizado e abriga o Shopping Popular de Santa Maria. Dessa forma, esse trabalho buscou identificar, a partir do histórico do local e do processo de tombamento, que elementos foram decisivos para que o bem chegasse à atual situação, realizando uma reflexão sobre os conflitos que permeiam esse processo. Para isso, se desenvolveu uma pesquisa bibliográfica tanto em relação à história da cidade, seus espaços culturais e o Cine Independência, contextualizando com outras importantes cidades do estado, quanto referente às políticas públicas preservacionistas e aos conceitos de memória e patrimônio. Além disso, se buscou a documentação ligada a esse processo de tombamento, bem como, junto a acervos da cidade, imagens e matérias publicadas em periódicos. Por fim, se realizou uma entrevista com o ex-prefeito de Santa Maria, buscando, assim, compreender melhor de que forma se deu esse processo e a constituição do Shopping Popular de Santa Maria