Extracting respiratory signals from thoracic cone beam CT projections

Patient respiratory signal associated with the cone beam CT (CBCT) projections is important for lung cancer radiotherapy. In contrast to monitoring an external surrogate of respiration, such signal can be extracted directly from the CBCT projections. In this paper, we propose a novel local principle component analysis (LPCA) method to extract the respiratory signal by distinguishing the respiration motion-induced content change from the gantry rotation-induced content change in the CBCT projections. The LPCA method is evaluated by comparing with three state-of-the-art projection-based methods, namely, the Amsterdam Shroud (AS) method, the intensity analysis (IA) method, and the Fourier-transform based phase analysis (FT-p) method. The clinical CBCT projection data of eight patients, acquired under various clinical scenarios, were used to investigate the performance of each method. We found that the proposed LPCA method has demonstrated the best overall performance for cases tested and thus is a promising technique for extracting respiratory signal. We also identified the applicability of each existing method.Comment: 21 pages, 11 figures, submitted to Phys. Med. Bio

Resonant dynamics of extreme mass-ratio inspirals in a perturbed Kerr spacetime

Extreme mass-ratio inspirals (EMRI) are one of the most sensitive probes of black hole spacetimes with gravitational wave measurements. In this work, we systematically analyze the dynamics of an EMRI system near orbital resonances, assuming the background spacetime is weakly perturbed from Kerr. Using the action-angle formalism, we have derived an effective resonant Hamiltonian that describes the dynamics of the resonant degree of freedom, for the case that the EMRI motion across the resonance regime. This effective resonant Hamiltonian can also be used to derive the condition that the trajectory enters/exits a resonant island and the permanent change of action variables across the resonance with the gravitational wave radiation turned on. The orbital chaos, on the other hand, generally leads to transitions between different branches of rotational orbits with finite changes of the action variables. These findings are demonstrated with numerical orbital evolutions that are mapped into representations using action-angle variables. This study is one part of the program of understanding EMRI dynamics in a generic perturbed Kerr spacetime, which paves the way of using EMRIs to precisely measure the black hole spacetime.Comment: 22 pages, 17 figure

Análisis de la viabilidad económico financiera y de la capacidad de creación de valor de un proyecto de energía eólica en Uruguay

[Resumen]: El presente trabajo se plantea como objetivo general el estudio de la viabilidad económico-financiera y la capacidad de generación de valor para sus accionistas de un proyecto de inversión en un Parque Eólico desarrollado por una empresa europea en Uruguay. El contexto en que se enmarca este Trabajo de Fin de Master es el de un país estable desde el punto de vista político, social e institucional; con una política energética que fomenta las energías renovables y que posee una Ley de Promoción de Inversiones. Para poder cumplir con el objetivo general, primeramente, se formulan estrategias de producto-servicio, de capital, financieras y de corto plazo. A partir de estas se elabora un plan financiero con un horizonte temporal de 27 años que integra el cuadro previsional de recursos generados, presupuesto de capital, presupuesto de tesorería, balances previsionales. Este plan financiero será la base para la estimación de los principales flujos de caja a lo largo de la vida útil del parque. Por tratarse de un proyecto que genera flujos futuros de caja en dólares, pero debe ser evaluado en euros, requiere emplear los mecanismos apropiados de conversión (tipos de cambio forward y tipos de descuento en euros). La discusión de viabilidad se realiza en un entorno de certeza y la de capacidad de generación de valor se realiza tanto en términos de certeza como de riesgo. Para esto, además de un análisis de sensibilidad del VAN a diferentes valores de las variables precio de venta de la energía, factor de capacidad y OPEX, se realiza una simulación de Montecarlo, a partir de considerar que estas tres variables se comportan como variables aleatorias. Finalmente, se obtiene el VAN en términos de probabilidad, lo que permite enriquecer el estudio de manera importante. El trabajo finaliza formulando un apartado con las conclusiones más relevantes.[Resumo]: O presente traballo formula como obxectivo xeral o estudo da viabilidade económico-financeira e a capacidade de xeración de valor para os seus accionistas dun proxecto de investimento nun parque eólico desenvolvido por unha empresa europea en Uruguai. O contexto en que se enmarca este traballo de fin de mestrado é o dun país estable dos puntos de vista político, social e institucional, cunha política enerxética que fomenta as fontes renovables e que posúe unha Lei de Promoción de Investimentos. Para dar cumprimento ao obxectivo xeral, primeiramente defínense as estratexias de produto-servizo, de capital, financeira e de curto prazo. A partir delas, confecciónase un plan financeiro cun horizonte temporal de 27 anos que integra o cadro previsional de recursos xerados, orzamento de capital, orzamento de tesouraría e balances previsionais. Este plan financeiro será a base para a estimación dos principais fluxos de caixa ao longo da vida útil do parque. Dado que se trata dun proxecto que xera fluxos futuros de caixa en dólares, pero debe ser avaliado en euros, cómpre empregar os mecanismos apropiados de conversión (tipos de cambio forward e tipos de desconto en euros). A discusión da viabilidade realízase nun contorno de certeza e a da capacidade de xeración de valor faise tanto en termos de certeza como de risco. Para isto, alén dunha análise de sensibilidade do VAN a diferentes valores das variables prezo de venda da enerxía, factor de capacidade e OPEX, realízase unha simulación de Montecarlo, a partir de considerar que estas tres variables se comportan como variables aleatorias. Finalmente, obtense o VAN en termos de probabilidade o que permite enriquecer o estudo de maneira importante. O traballo remata formulando un apartado coas conclusión máis relevantes.[Abstract]: The present work considers as a general objective the study of the economic-financial viability and the ability to generate value for its shareholders of an investment project in a wind farm developed by a European company in Uruguay. The context in which this End of Master Project is framed is that of a stable country from the political, social and institutional point of view; with an energy policy that promotes renewable energies and that has an Investment Promotion Law. First, product-service, capital, financial and short-term strategies are formulated to meet the general objective. From these a financial plan is drawn up with a time horizon of 27 years that integrates the forecasting plan of generated resources, capital budget, treasury budget, forecasting balances. This financial plan will be the basis for estimating the main cash flows throughout the useful life of the park. Because it is a project that generates future cash flows in dollars, but must be evaluated in euros, it requires the use of appropriate conversion mechanisms (forward exchange rates and discount rates in euros). The viability discussion takes place in an environment of certainty and that of value generation capacity is carried out both in terms of certainty and risk. For this, in addition to a sensitivity analysis of the NPV to different values of the variables of energy sales price, capacity factor and OPEX, a Monte Carlo simulation is carried out, considering that these three variables behave as random variables . Finally, the NPV is obtained in terms of probability, which allows enriching the study in an important way. The work ends by formulating a section with the most relevant conclusions.Traballo fin de mestrado (UDC.ECO). Banca e finanzas. Curso 2018/201

Contribution of mixing to upward transport across the tropical tropopause layer (TTL)

During the second part of the TROCCINOX campaign that took place in Brazil in early 2005, chemical species were measured on-board the high-altitude research aircraft Geophysica (ozone, water vapor, NO, NOy, CH4 and CO) in the altitude range up to 20 km (or up to 450 K potential temperature), i.e. spanning the entire TTL region roughly extending between 350 and 420 K. Here, analysis of transport across the TTL is performed using a new version of the Chemical Lagrangian Model of the Stratosphere (CLaMS). In this new version, the stratospheric model has been extended to the earth surface. Above the tropopause, the isentropic and cross-isentropic advection in CLaMS is driven by meteorological analysis winds and heating/cooling rates derived from a radiation calculation. Below the tropopause, the model smoothly transforms from the isentropic to the hybrid-pressure coordinate and, in this way, takes into account the effect of large-scale convective transport as implemented in the vertical wind of the meteorological analysis. As in previous CLaMS simulations, the irreversible transport, i.e. mixing, is controlled by the local horizontal strain and vertical shear rates. Stratospheric and tropospheric signatures in the TTL can be seen both in the observations and in the model. The composition of air above ≈350 K is mainly controlled by mixing on a time scale of weeks or even months. Based on CLaMS transport studies where mixing can be completely switched off, we deduce that vertical mixing, mainly driven by the vertical shear in the tropical flanks of the subtropical jets and, to some extent, in the the outflow regions of the large-scale convection, offers an explanation for the upward transport of trace species from the main convective outflow at around 350 K up to the tropical tropopause around 380 K