Classical Emergence of Intrinsic Spin-Orbit Interaction of Light at the Nanoscale

Traditionally, in macroscopic geometrical optics intrinsic polarization and spatial degrees of freedom of light can be treated independently. However, at the subwavelength scale these properties appear to be coupled together, giving rise to the spin-orbit interaction (SOI) of light. In this work we address theoretically the classical emergence of the optical SOI at the nanoscale. By means of a full-vector analysis involving spherical vector waves we show that the spin-orbit factorizability condition, accounting the mutual influence between the amplitude (spin) and phase (orbit), is fulfilled only in the far-field limit. On the other side, in the near-field region, an additional relative phase introduces an extra term that hinders the factorization and reveals an intricate dynamical behavior according to the SOI regime. As a result, we find a suitable theoretical framework able to capture analytically the main features of intrinsic SOI of light. Besides allowing for a better understanding into the mechanism leading to its classical emergence at the nanoscale, our approach may be useful in order to design experimental setups that enhance the response of SOI-based effects.Comment: 10 pages, 5 figure

Técnicas quirúrgicas en disección aórtica tipo A

ResumenLa cirugía de la disección aórtica tipo A es una situación clínica que asocia invariablemente una elevada mortalidad. El principal desafío al que se enfrenta el cirujano consiste en mantener con vida al paciente una vez superado el episodio agudo, independientemente de la evolución de la afección residual aórtica y de la necesidad o no de reintervención posterior. Los objetivos quirúrgicos se dirigen a reinstaurar el flujo a través de la luz verdadera, eliminar el desgarro (rotura) principal, y restablecer la anatomía de la raíz y la competencia de la válvula aórtica para limitar los efectos de la malperfusión visceral y coronaria, el riesgo de rotura y taponamiento cardiaco, así como el estado de shock. El contexto clínico de cada paciente, así como la infraestructura disponible y la experiencia del cirujano determinan en último lugar la técnica más adecuada a aplicar.AbstractType A aortic dissection surgery is invariably associated with a high mortality rate. The first challenge that the surgeon faces is to keep the patient alive, regardless of the residual disease in the remaining aorta and the need for re-intervention in the future. Surgical goals are aimed at restoring flow on the true lumen, excluding a main aortic tear and restoring the anatomy and competence for the aortic root and the aortic valve, in order to limit the consequences of visceral and coronary malperfusion, the risk of rupture and tamponade, as well as shock. The clinical context, the available infrastructure and the experience of the surgeon are ultimate determinants for which the most suitable technique should be performed

O pastor, o doutor e o Big Data

The rise of the Internet as a space for global interaction makes the political subjectivation of automated surveillance especially important for understanding the mechanisms of social control in our current culture. This essay approaches mass electronic surveillance from the perspective of the processes of production of subjectivities among users of the Net. It will briefly outline a history of the production of subjects as related to the necessity of expressing a certain truth about themselves, of confessing and conforming to a normality regulated by the strategic frameworks of power. At the same time, it will attempt to associate the logic of that history with the rise of Big Data as a device for the tracking, discrimination and management of personal data. Finally, the paper will provide some reflections on the significance of resistance to the loss of privacy in digital culture.La consolidación de Internet como espacio de relación global implica que la subjetivación política de la vigilancia automatizada adquiera especial relevancia a la hora de comprender los mecanismos de control social en nuestra cultura. Este ensayo pretende ser una aproximación a la cuestión de la vigilancia masiva desde la perspectiva de los procesos de configuración de subjetividades de los usuarios de la red. Es por ello que se procurará trazar sucintamente un recorrido histórico de producción de sujetos en torno a la necesidad de expresar cierto tipo de verdad sobre sí mismos, de confesar y de conformar con una normalidad reglada por los marcos estratégicos del poder. Al mismo tiempo, se tratará de poner en relación la lógica de ese recorrido con el advenimiento del Big Data como dispositivo de rastreo, discriminación y tratamiento de información personal; para, finalmente, reflexionar sobre el sentido de la resistencia a la pérdida de privacidad en la cultura digital.A consolidação da Internet como espaço de relação global resulta na subjetivação políticade vigilância automatizada que vai adquirindo especial relevância na hora de compreender os mecanismos de controle social em nossa cultura. Este ensaio pretende aproximar-se à questão da vigilância massiva desde a perspectiva dos processos configuradores de subjetividades que incidem sobre os usuários da rede. Para isso será delimitado um período histórico de produção de sujeitos ao redor da necessidade de expressar um certo tipo de verdade sobre si mesmo, de confessar e de adequar-se a uma normalidade regrada por marcos estratégicos depoder. Simultaneamente, esta lógica será relacionada ao surgimento do Big Data como dispositivo de rastreio, registro e tratamento de informação pessoal para, finalmente, refletir sobre o sentido da resistência à perda de privacidade na cultura digital

Single-Camera 3D Microscope Scanner

Sistema de escáner microscópico 3D basado en imágenes capturadas por una única cámara desplazada sobre la superficie a escánear. Las imágenes se combinan para obtener una imagen de alta resolución de la superficie completa, y se aplican técnicas de reconstrucción 3D para calcular su altura relativa

Substance Use Initiation among Mexican Children: An Examination of Individual and Ecological Factors

Mexico is experiencing increased rates of substance use among children and adolescents. This is concerning as early substance use is associated with an increased risk for developing mental and physical health problems during adulthood. These outcomes may be prevented through early identification and intervention before individuals encounter the negative consequences of substance use/abuse. The current dissertation sought to improve our knowledge regarding factors associated with substance use and intention for first time use among Mexican children. Three manuscripts examined child individual characteristics and aspects of their environment. The first manuscript examined demographic characteristics to determine whether particular groups of children were at increased risk for substance use and intensions for first time use. We found that being a boy, of indigenous background, non-religious, and over developmental age for grade were all associated with risk. The second manuscript focuses on examining parent characteristics and practices on substance use and intention for first time use. We found that parental illicit substance use was associated with the largest increases in risk and positive parenting was a protective factor. The third manuscript utilized machine learning, an algorithmic approach that predicts membership in one of two groups, to assist in the identification of high value factors that distinguish between substance users and non-users. Findings from this research identified factors associated with childhood substance use at individual and environmental levels. Being a boy and having a best friend or father that used illicit substances were the key indicators that could provide valuable information as screening questions. These findings provide valuable information needed to inform the development of early substance use prevention programs in Mexico. Results also suggest that machine learning may be an important tool in uncovering information that could bolster prevention efforts by improving our ability to identify children at risk for substance use. This research was supported by the Utah State University Psychology Department and School of Graduate Studies

Cryptocurrencies: a theorical and financial analysis.

Treball Final de Grau en Finances i Comptabilitat. Codi: FC1049. Curs acadèmic: 2018/2019Cryptocurrencies represent an alternative and modern pay mode, through new technologies. Although cryptocurrencies were used before the Great Recession of 2008, this fact achieved the development and international boom of cryptocurrencies, especially Bitcoin. The objective of this paper is to analyze cryptocurrencies, on one hand from a theoretical view (explaining history, functioning, legislation and economic effects), and on the other hand from a practical view, showing the price index between the main cryptocurrencies and other currencies, with the objective of showing the effect of cryptocurrencies, trying to find out if they suppose an investment and an alternative payment, or cryptocurrencies, or they are just unstable and at risk of become an economic "bubble". Finally, in the conclusion of this paper the potential that cryptocurrencies could have in the future will be explained

Near-Field Directionality Beyond the Dipole Approximation: Electric Quadrupole and Higher-Order Multipole Angular Spectra

Within the context of spin-related optical phenomena, the near-field directionality is generally understood from the quantum spin Hall effect of light, according to which the transverse spin of surface or guided modes is locked to the propagation direction. So far, most previous works have been focused on the spin properties of circularly polarized dipolar sources. However, in near-field optics, higher-order multipole sources (e.g., quadrupole, octupole, and so on) might become relevant, so a more in-depth formulation would be highly valuable. Building on the angular spectrum representation, we provide a general, analytical, and ready-to-use treatment in order to address the near-field directionality of any multipole field, particularizing to the electric quadrupole case. Besides underpinning and upgrading the current framework on spin-dependent directionality, our results may open up new perspectives for engineering light-matter coupling at the nanoscale.Comment: 7 pages, 2 figures. Supplemental Material (19 pages). Supplemental tools (calculator of angular spectra and animation) available at https://doi.org/10.5281/zenodo.267790

Spatiotemporal Stacked Sequential Learning for Pedestrian Detection

Pedestrian classifiers decide which image windows contain a pedestrian. In practice, such classifiers provide a relatively high response at neighbor windows overlapping a pedestrian, while the responses around potential false positives are expected to be lower. An analogous reasoning applies for image sequences. If there is a pedestrian located within a frame, the same pedestrian is expected to appear close to the same location in neighbor frames. Therefore, such a location has chances of receiving high classification scores during several frames, while false positives are expected to be more spurious. In this paper we propose to exploit such correlations for improving the accuracy of base pedestrian classifiers. In particular, we propose to use two-stage classifiers which not only rely on the image descriptors required by the base classifiers but also on the response of such base classifiers in a given spatiotemporal neighborhood. More specifically, we train pedestrian classifiers using a stacked sequential learning (SSL) paradigm. We use a new pedestrian dataset we have acquired from a car to evaluate our proposal at different frame rates. We also test on a well known dataset: Caltech. The obtained results show that our SSL proposal boosts detection accuracy significantly with a minimal impact on the computational cost. Interestingly, SSL improves more the accuracy at the most dangerous situations, i.e. when a pedestrian is close to the camera.Comment: 8 pages, 5 figure, 1 tabl

A study of flight cancellation and delays in the UK

Flight delays and flight cancellations have always been a problem for the aviation industry. However, the different nature of both phenomena has made research focus almost solely on studying and predicting delays. This is due to the fact that, ultimately, it is the airline who decides whether a flight gets cancelled, whereas delays are an involuntary result of a vast array of different causes, many times due to bad management practices by airports and airlines. The literature has studied delays from a wide range of perspectives, taking into consideration several factors that influence them. Some studies have predicted delays from a machine learning perspective, while others have taken into consideration the importance of the time series component of the data. However, research shows that it is actually flight cancellations that is the most important determinant for consumer dissatisfaction and complaints, being detrimental for airlines' reputation and resulting in passengers switching carriers. Therefore, a more careful study and comprehension of what drives and affects flight cancellations is needed. Analyzing the research that has focused on understanding the underlying patterns of cancellations, what can mostly be found are theoretical and machine learning approaches. Some findings have been made in determining what further increases or helps reduce the number of cancellations, like the importance of a well-managed airport capacity to improve service quality in terms of cancellations \citep{mead2000flight}. As mentioned, there is also behavioral research on the consequences that cancellations have on airlines (Yanying et al., 2019), pointing towards an increased dissatisfaction and distrust from customers, resulting in serious damages for the airline's corporate reputation and passengers' loyalty. Nevertheless, there are components of the understanding of cancellations that remained unclear. On the one hand, a thorough time series analysis of cancellations needs to be done. In fact, as Lemke et al. (p. 85, 2009) point out, the diverse characteristics and underlying data generation processes of time series has resulted in the fact that "it seems as if no method has ever proven successful across various studies and time series". On the other hand, delays and cancellations are two phenomena that cannot be completely understood independently and, although there is a vast number of studies analyzing delay propagation, there are no conclusive results on the impact of delays on cancellations. Therefore, research must determine whether taking delays into account when analyzing cancellations improves the accuracy of cancellations forecasts and the relation among these parameters. Lastly, as they cannot only be studied alone, a more thorough study of the capacity factors that influence the number of cancellations also needs to be done. Moreover, the outbreak of the COVID-19 in the midst of the research process made the accuracy of the forecasts deviate. Delays and cancellations have evolved dramatically differently over the first months of 2020. Hence, there is a need for taking a new parameter into account that would help make sense of the abnormal cancellations in 2020 and improve forecasts accuracies. For this, the behavioral changes of the population have been taking into consideration, which has been done with Google Trends. Also, it opened a door for understanding the passengers' behavioral reaction towards air travel under these circumstances, taking into consideration both local and global factors. Therefore, this study is divided into three sections. The first one studies the relationship between delays and cancellations from a time series perspective, and it is found that taking delays into account as a parameter in the study of cancellations improves the accuracy of time series forecasts at different levels of aggregation. The second one focuses on studying the relevance of competition and network factors in the distribution of cancellations. Flights arriving or departing from a hub airport are found to be less likely to be cancelled, pointing towards the relevance of maintaining networks for airlines, thus strengthening passenger reliability and trust. However, it was found that route and airport competition, while confirming the nature of the impact, was not statistically significant in predicting flight cancellations. Finally, it was found that public concern in the context of a global pandemic varies according to local circumstances, and that shortly after the first and most shocking news, both concern and a positive consumer attitude decrease to a stabilized level, which indicating double-edged passive behavior, in which both concern and willingness to purchase flight or event tickets (i.e., requiring travel or social gatherings) are reduced to similarly low levels for at least one month after the initial mayhe

Una alternativa actual al dualismo en Psicología: la Ciencia Conductual Contextual

El artículo busca constatar el carácter dualista que aún invade la Psicología, y cómo los problemas pragmáticos y filosóficos de la misma tienen como solución más socorrida el acudir a un monismo materialista, encarnado en la figura del reduccionismo cerebrocentrista. Así mismo, se presentan las características, filosofía y aplicaciones de la CBS (Ciencia Conductual Contextual) en vistas a ofrecer una alternativa dentro de la propia Psicología que supere el dualismo imperante y preserve la independencia de la Psicología como campo autónomo en la ciencia, entre la biología y la sociología.The article tries to verify the dualist character that still invades psychology, and how the pragmatic and philosophical problems of it have as a most useful solution to resort to a materialist monism, embodied in the figure of brain-centered reductionism. Likewise, the characteristics, philosophy and applications of the CBS (Contextual Behavioral Science) are presented in order to offer an alternative within the psychology that overcomes the prevailing dualism and preserves the independence of psychology as an autonomous field in science, among biology and sociology