Response of the Southern Ocean circulation to changes in global climate

The Southern Ocean circulation plays a central role in the dynamics of past and future global climate change. However, due to a scarcity of observations and the difficulty of accurately modelling the Southern Ocean, we lack a comprehensive understanding of how the circulation responds to change. The energetic eddy field directly impacts the response of the circulation, but the small scale of the eddies has generally been below the resolution of numerical ocean models. This thesis makes use of two high resolution idealised ocean models to investigate the role of eddies in modifying the response of the Southern Ocean circulation to changing wind stress and surface buoyancy forcing. The simulations demonstrate that the eddy field is significant in the dynamical response, but that the impact on different aspects of the circulation is complex and subtle. The Antarctic Circumpolar Current (ACC) transport increases only weakly in response to enhanced Southern Ocean wind stress, due to the enhanced eddy field, which efficiently eliminates momentum input. In contrast, the eddy field only partially compensates wind- driven increases in the upper overturning circulation, resulting in a moderate overturning increase in response to enhanced westerly winds. Southern Ocean heat uptake is also shown to be dependent on changes in the eddy field. Mid-depth warming occurs primarily due to a decrease in the upward eddy heat flux, associated with reduced isopycnal temperature gradients in a warmer climate. However, increased wind stress may reduce the mid-depth heat uptake; a transient cooling trend arises from the wind-driven enhancement of the vertical eddy heat flux. The uncoupled idealised models also permit an in-depth analysis of the response of the Southern Ocean overturning to changes in surface buoyancy forcing. A suite of buoyancy forcing perturbations show that mid-latitude heat and freshwater fluxes may be as significant as wind stress in altering the strength of the upper overturning circulation. Analysis of the transient model response to a range of surface buoyancy forcing perturbations also indicates that recent observations are consistent with a slowdown of the lower overturning cell. In summary, this thesis has refined our understanding of how the large scale Southern Ocean circulation responds to atmospheric change and the role of the eddy field in modifying that response. This work provides a basis to interpret the more complicated response of coupled and coarse resolution models

Queering Domestic Violence to Straighten Out Criminal Law: What Might Happen When Queer Theory and Practice Meet Criminal Law\u27s Conventional Responses to Domestic Violence

A partir de los resultados de los exámenes de Estado de la educación media en Colombia (ICFES)en el periodo 1980–2009, el estudio estima dentro de un análisis multinivel, el efecto colegiopor sector educativo y para tres pruebas (total, lenguaje y matemáticas). Los resultados sugierenque independientemente de la prueba, el efecto colegio público siempre ha sido menor que elprivado y que la incidencia en la prueba de matemáticas es siempre mínima. Igualmente, quea partir del 2000 se registra una caída considerable en el coeficiente, lo cual puede estar relacionadocon el cambio de las pruebas en dicho año. Finalmente, con un análisis intertemporalde los percentiles de los puntajes, se encuentra que los colegios privados tradicionalmente hanestado mejor posicionados en las pruebas que los públicos.A partir dos resultados das provas de ingresso na educação superior na Colômbia (ICFES) noperíodo entre 1980 e 2009, o estudo estima, dentro de uma análise multinível, o “efeito colégio”em cada setor educativo e para três provas distintas. Os resultados sugerem que independentementeda prova, o “efeito colégio” público sempre foi menor que o privado e que a incidênciana prova de matemática é sempre a mínima. Também a partir de 2000, se registra uma quedaconsiderável no coeficiente a qual pode estar relacionada com a alteração das provas no dito ano.Finalmente, com uma análise intertemporal dos percentis das pontuações, se conclui que oscolégios privados tradicionalmente se posicionaram melhor que os colégios públicos nas provas.Based on the results from ICFES tests (Colombian equivalent of the American SATs) from 1980to 2009, the study uses a hierarchical/multi-level analysis to provide an estimate of the schooleffect in each educational sector for three different tests. The results suggest that the publicschool effect has always been smaller than that of private schools in the last thirty years andthat the effect on the mathematics section of the test is always smaller, regardless of the educationalsector. They also indicate that since 2000 there has been a considerable drop in thecoefficient, which could be related to the change in the tests that year. Lastly, an intertemporalanalysis of score percentiles reveals that private schools have traditionally ranked higher thantheir public counterparts

Flux Limitations of Continuous Atom Lasers

If atom lasers are to transform many fields of physics, as well as find applications in industry, the most essential development needed is increased atom flux. In this thesis we report on the experimental observation of fundamental limits on the flux of continuous atom lasers. The flux produced by the commonly used radio frequency outcoupler, can not be arbitrarily increased by increasing the strength of the outcoupling. Above a critical Rabi frequency, the atom laser shows large classical density fluctuations, due to coupling between the multiple Zeeman states. In our system this critical Rabi frequency is about 1 kHz. Futhermore, at large coupling strengths (> 4 kHz for our experimetnal parameters), the continuous atom laser output completely switches off, as a result of the atoms remaining trapped in a bound state. In addition to the investigations of the radio frequency outcoupler, we have demonstrated the first continuous Raman outcoupled atom laser. Preliminary data indicates that the Raman outcoupler will be flux limited in a similar way to the radio frequency outcoupler