3,695 research outputs found
Relativistic Quantum Scattering of High Energy Fermions in the Presence of Phase Transition
We study the high energy behaviour of fermions hitting a general wall caused
by a first-order phase transition. The wall profile is introduced through a
general analytic function. The reflection coefficient is computed in the high
energy limit and expressed in terms of the poles of the wall profile function.
It is shown that the leading singularity gives the high energy behaviour.Comment: 10 page
RCS of engine inlets by a spectral iterative technique
A novel algorithm designed to compute efficiently and accurately the HF electromagnetic scattering from open-ended waveguide cavities is presented. The cavity is converted into a stepped-waveguide model so that the field spectrums are propagated, forward and backward, along each waveguide section. As boundary conditions for perfect electric conductors are applied via image theory, they are of local nature and take into account only the first order interactions between each pair of waveguide sections. Accordingly, additional forward-backward iterations must be performed if multiple interactions are to be taken into account. Finally, the RCS due to the interior irradiation is calculated by a Kirchhoff-based aperture integral. Good agreement with Method of Moments and Hybrid Modal solutions is found, as well as with experimental data, for 2-D and 3-D cavities.Peer ReviewedPostprint (published version
Performance evaluation of the Hilbert–Huang transform for respiratory sound analysis and its application to continuous adventitious sound characterization
© 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/The use of the Hilbert–Huang transform in the analysis of biomedical signals has increased during the past few years, but its use for respiratory sound (RS) analysis is still limited. The technique includes two steps: empirical mode decomposition (EMD) and instantaneous frequency (IF) estimation. Although the mode mixing (MM) problem of EMD has been widely discussed, this technique continues to be used in many RS analysis algorithms.
In this study, we analyzed the MM effect in RS signals recorded from 30 asthmatic patients, and studied the performance of ensemble EMD (EEMD) and noise-assisted multivariate EMD (NA-MEMD) as means for preventing this effect. We propose quantitative parameters for measuring the size, reduction of MM, and residual noise level of each method. These parameters showed that EEMD is a good solution for MM, thus outperforming NA-MEMD. After testing different IF estimators, we propose Kay¿s method to calculate an EEMD-Kay-based Hilbert spectrum that offers high energy concentrations and high time and high frequency resolutions. We also propose an algorithm for the automatic characterization of continuous adventitious sounds (CAS). The tests performed showed that the proposed EEMD-Kay-based Hilbert spectrum makes it possible to determine CAS more precisely than other conventional time-frequency techniques.Postprint (author's final draft
Normative and Audience Discourses on Public Service Journalism at a “Critical Juncture”: the Case of TVE in Spain
The concept of journalism, its metatheory and, in particular, public service journalism is
regulated by feedback between political models (legal and normative framework), academic
precepts and social practices. Scant attention has been paid to date to the impact that these
models have on citizens’ discourses, which is especially relevant at “critical junctures”, i.e.
periods in which the old institutions are collapsing and require renovation (McChesney,
2007). Hence, this paper addresses the issue in the Spanish context in order to explore the
similarities and differences between the academic/legal/normative framework and audience
discourses. The former has been studied using documents, reports and legislation, and the
latter explored by means of discussion groups with viewers of the newscasts of Televisión
Española (TVE)
Multichannel analysis of normal and continuous adventitious respiratory sounds for the assessment of pulmonary function in respiratory diseases
Premi extraordinari doctorat UPC curs 2015-2016, àmbit d’Enginyeria IndustrialRespiratory sounds (RS) are produced by turbulent airflows through the airways and are
inhomogeneously transmitted through different media to the chest surface, where they can be recorded
in a non-invasive way. Due to their mechanical nature and airflow dependence, RS are affected by
respiratory diseases that alter the mechanical properties of the respiratory system. Therefore, RS provide
useful clinical information about the respiratory system structure and functioning.
Recent advances in sensors and signal processing techniques have made RS analysis a more objective
and sensitive tool for measuring pulmonary function. However, RS analysis is still rarely used in clinical
practice. Lack of a standard methodology for recording and processing RS has led to several different
approaches to RS analysis, with some methodological issues that could limit the potential of RS analysis
in clinical practice (i.e., measurements with a low number of sensors, no controlled airflows, constant
airflows, or forced expiratory manoeuvres, the lack of a co-analysis of different types of RS, or the use
of inaccurate techniques for processing RS signals).
In this thesis, we propose a novel integrated approach to RS analysis that includes a multichannel
recording of RS using a maximum of five microphones placed over the trachea and the chest surface,
which allows RS to be analysed at the most commonly reported lung regions, without requiring a large
number of sensors. Our approach also includes a progressive respiratory manoeuvres with variable
airflow, which allows RS to be analysed depending on airflow. Dual RS analyses of both normal RS
and continuous adventitious sounds (CAS) are also proposed. Normal RS are analysed through the RS
intensity–airflow curves, whereas CAS are analysed through a customised Hilbert spectrum (HS),
adapted to RS signal characteristics.
The proposed HS represents a step forward in the analysis of CAS. Using HS allows CAS to be fully
characterised with regard to duration, mean frequency, and intensity. Further, the high temporal and
frequency resolutions, and the high concentrations of energy of this improved version of HS, allow CAS
to be more accurately characterised with our HS than by using spectrogram, which has been the most
widely used technique for CAS analysis.
Our approach to RS analysis was put into clinical practice by launching two studies in the Pulmonary
Function Testing Laboratory of the Germans Trias i Pujol University Hospital for assessing pulmonary
function in patients with unilateral phrenic paralysis (UPP), and bronchodilator response (BDR) in
patients with asthma. RS and airflow signals were recorded in 10 patients with UPP, 50 patients with
asthma, and 20 healthy participants.
The analysis of RS intensity–airflow curves proved to be a successful method to detect UPP, since we
found significant differences between these curves at the posterior base of the lungs in all patients whereas no differences were found in the healthy participants. To the best of our knowledge, this is the
first study that uses a quantitative analysis of RS for assessing UPP.
Regarding asthma, we found appreciable changes in the RS intensity–airflow curves and CAS features
after bronchodilation in patients with negative BDR in spirometry. Therefore, we suggest that the
combined analysis of RS intensity–airflow curves and CAS features—including number, duration, mean
frequency, and intensity—seems to be a promising technique for assessing BDR and improving the
stratification of BDR levels, particularly among patients with negative BDR in spirometry.
The novel approach to RS analysis developed in this thesis provides a sensitive tool to obtain objective
and complementary information about pulmonary function in a simple and non-invasive way. Together
with spirometry, this approach to RS analysis could have a direct clinical application for improving the
assessment of pulmonary function in patients with respiratory diseases.Los sonidos respiratorios (SR) se generan con el paso del flujo de aire a través de las vías respiratorias y se transmiten de forma no homogénea hasta la superficie torácica. Dada su naturaleza mecánica, los SR se ven afectados en gran medida por enfermedades que alteran las propiedades mecánicas del sistema respiratorio. Por lo tanto, los SR proporcionan información clínica relevante sobre la estructura y el funcionamiento del sistema respiratorio. La falta de una metodología estándar para el registro y procesado de los SR ha dado lugar a la aparición de diferentes estrategias de análisis de SR con ciertas limitaciones metodológicas que podrían haber restringido el potencial y el uso de esta técnica en la práctica clínica (medidas con pocos sensores, flujos no controlados o constantes y/o maniobras forzadas, análisis no combinado de distintos tipos de SR o uso de técnicas poco precisas para el procesado de los SR). En esta tesis proponemos un método innovador e integrado de análisis de SR que incluye el registro multicanal de SR mediante un máximo de cinco micrófonos colocados sobre la tráquea yla superficie torácica, los cuales permiten analizar los SR en las principales regiones pulmonares sin utilizar un número elevado de sensores . Nuestro método también incluye una maniobra respiratoria progresiva con flujo variable que permite analizar los SR en función del flujo respiratorio. También proponemos el análisis combinado de los SR normales y los sonidos adventicios continuos (SAC), mediante las curvas intensidad-flujo y un espectro de Hilbert (EH) adaptado a las características de los SR, respectivamente. El EH propuesto representa un avance importante en el análisis de los SAC, pues permite su completa caracterización en términos de duración, frecuencia media e intensidad. Además, la alta resolución temporal y frecuencial y la alta concentración de energía de esta versión mejorada del EH permiten caracterizar los SAC de forma más precisa que utilizando el espectrograma, el cual ha sido la técnica más utilizada para el análisis de SAC en estudios previos. Nuestro método de análisis de SR se trasladó a la práctica clínica a través de dos estudios que se iniciaron en el laboratorio de pruebas funcionales del hospital Germans Trias i Pujol, para la evaluación de la función pulmonar en pacientes con parálisis frénica unilateral (PFU) y la respuesta broncodilatadora (RBD) en pacientes con asma. Las señales de SR y flujo respiratorio se registraron en 10 pacientes con PFU, 50 pacientes con asma y 20 controles sanos. El análisis de las curvas intensidad-flujo resultó ser un método apropiado para detectar la PFU , pues encontramos diferencias significativas entre las curvas intensidad-flujo de las bases posteriores de los pulmones en todos los pacientes , mientras que en los controles sanos no encontramos diferencias significativas. Hasta donde sabemos, este es el primer estudio que utiliza el análisis cuantitativo de los SR para evaluar la PFU. En cuanto al asma, encontramos cambios relevantes en las curvas intensidad-flujo yen las características de los SAC tras la broncodilatación en pacientes con RBD negativa en la espirometría. Por lo tanto, sugerimos que el análisis combinado de las curvas intensidad-flujo y las características de los SAC, incluyendo número, duración, frecuencia media e intensidad, es una técnica prometedora para la evaluación de la RBD y la mejora en la estratificación de los distintos niveles de RBD, especialmente en pacientes con RBD negativa en la espirometría. El método innovador de análisis de SR que se propone en esta tesis proporciona una nueva herramienta con una alta sensibilidad para obtener información objetiva y complementaria sobre la función pulmonar de una forma sencilla y no invasiva. Junto con la espirometría, este método puede tener una aplicación clínica directa en la mejora de la evaluación de la función pulmonar en pacientes con enfermedades respiratoriasAward-winningPostprint (published version
El palimpsesto urbano: Paul Auster, Wayne Wang, Wong Kar Wai
Uno de los espacios más recurrentes de las películas cinematográficas ha sido, desde el cine de los orígenes, el espacio urbano. Trenes entrando y saliendo de ciudades, calles abarrotadas... Pero también el espacio de conflicto en el primer cine narrativo (Chaplin) y en las Sinfonías de una ciudad de las primeras vanguardias. En el siglo XXI Wayne Wang –en relación directa con Paul Auster– y Wongg Kar Wai dibujan una línea de continuidad con estas tendencias del cine primitivo para contribuir a la caracterización de los personajes.One of the most recurrent spaces on the motion pictures has been the urban space since the origin of cinema. Railways coming up and down all along the city, crowds on the streets... But even the space of conflict in the first narrative cinema (Chaplin) and at the Symphonies of the city during the first vanguards. Nowadays Wayne Wang –related to Paul Auster– and Wongg Kar Wai draw a clear line with that silent films to contrinbute on the characterization.Un certain espace des films, depuis de la naissance du cinéma, est l’espace
urbain. Des trains en parcourant la cité, des multitudes autour les rues... Mais c’est aussi l’espace de conflit dans le prémier cinema narratif (Chaplin) el dans les Symphonie de la cité de l’avantgarde. Au XXIème siecle Wayne Wang –mis en relation avec Paul Auster– et Wong Kar Wai travaillent
dans la même tendence pour contribuer à la caractérisation des personnages
Francisco Ayala y el cine: reflexión teórica y producción literaria
Francisco Ayala, un escritor en la vanguardia de su tiempo. Vanguardia en sentido literario y artístico y vanguardia en el sentido práctico y de la realidad social. Ayala no es un mero espectador ante el nacimiento del séptimo arte, el fenómeno social, comunicativo y artístico del siglo XX por excelencia; sino que indagó en él y profundizó en sus técnicas expresivas hasta el punto de que se ha llegado a afirmar que Ayala escribe con una cámara. Partiendo de la aportación teórica y ensayística de Ayala es posible comprender el apasionamiento del escritor por el cine y por su tiempo y cómo esto se refleja en términos expresivos en obras como El Jardín de las Delicias, Cazador en el alba o Historia de un amanecer.Francisco Ayala is a writer in the vanguard of his time. On the sense of art and literature but on a sense social sense too. Ayala is not just an onlooker in front of the first steps of the seventh art, the most important phenomena in terms of society, communication and art on the 20th century. He reached deeper about this. Even it is said that Ayala writes with a camera. Firstly, assuming the different essays it is possible to deal with the writer's keen about cinema what is possible to be read in some works like El Jardín de las Delicias or Historia de un amanecer.Francisco Ayala, un écrivain á l'avant-garde de son temps. Avant-garde au
sens littéraire et artistique, avant-garde au sens pratique et de la réalité sociale. Ayala n'est pas un simple spectateur face á la naissance du septiéme art, le phénoméne social, communicatif et artistique par excellence, mais il y a réfléchi et il en a analysé a fond les techniques d'expression a un point tel qu'on a pu diré qu'Ayala écrit avec une camera. En partant des apports théoriques d'Ayala dans ses essais, il est possible de comprendre la passion de l'écrivain pour le cinema et pour son époque, et comment cela se refléte en termes d'expression dans des oeuvres comme El jardín de las delicias, Cazador en el alba, ou Historia de un amanecer
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