Uncertainty decoding on Frequency Filtered parameters for robust ASR

The use of feature enhancement techniques to obtain estimates of the clean parameters is a common approach for robust automatic speech recognition (ASR). However, the decoding algorithm typically ignores how accurate these estimates are. Uncertainty decoding methods incorporate this type of information. In this paper, we develop a formulation of the uncertainty decoding paradigm for Frequency Filtered (FF) parameters using spectral subtraction as a feature enhancement method. Additionally, we show that the uncertainty decoding method for FF parameters admits a simple interpretation as a spectral weighting method that assigns more importance to the most reliable spectral components. Furthermore, we suggest combining this method with SSBD-HMM (Spectral Subtraction and Bounded Distance HMM), one recently proposed technique that is able to compensate for the effects of features that are highly contaminated (outliers). This combination pursues two objectives: to improve the results achieved by uncertainty decoding methods and to determine which part of the improvements is due to compensating for the effects of outliers and which part is due to compensating for other less deteriorated features.Publicad

Contribuciones al reconocimiento robusto de habla

En esta tesis doctoral abordamos el problema del reconocimiento robusto de habla. En primer lugar, estudiamos el efecto de los ruidos aditivos sobre el proceso de reconocimiento. Mostramos que el deterioro de la eficacia de los reconocedores se debe, en parte, al excesivo poder de decisión que recae sobre características de entrada que están contaminadas de forma muy severa (outliers). El método que denominamos bounded-distance HMM (BD-HMM) es capaz de limitar la contribución de estas muestras en el reconocedor. Sin embargo, BD-HMM no actúa sobre el resto de observaciones que, sin estar tan altamente contaminadas, sí que están afectadas por la presencia de ruidos aditivos. Por el contrario, sustracción espectral actúa sobre todas las observaciones pero presenta el inconveniente de introducir distorsiones que afectan negativamente a las prestaciones de los reconocedores. En esta tesis mostramos que estas distorsiones producen un aumento del número de outliers. De este modo, encontramos que BD-HMM y sustracción espectral se complementan perfectamente. Nuestros experimentos muestran que esta combinación generalmente supera las tasas de reconocimiento que consiguen tanto BD-HMM como sustracción espectral cuando se aplican de forma aislada. De hecho, las mejoras introducidas por la combinación propuesta, especialmente a SNRs bajas y medias, suelen ser superiores a la suma de las mejoras conseguidas por BD-HMM y sustracción espectral. Por otro lado, la estimación de los parámetros limpios que realiza sustracción espectral deja un cierto nivel de incertidumbre que los reconocedores convencionales no tienen en consideración. En esta tesis modificamos el proceso de reconocimiento para tener en cuenta esta incertidumbre cuando los sistemas se diseñan empleando la parametrización Frequency Filtered (FF). Al permanecer esta parametrización en el dominio del log-espectro, los métodos propuestos se pueden interpretar de una forma sencilla como métodos de ponderación espectral que asignan mayor poder discriminativo a las frecuencias del espectro más fiables. Los resultados que mostramos en esta tesis apoyan la necesidad de incorporar información sobre la incertidumbre de las observaciones para aumentar la robustez del proceso de reconocimiento. Por último, en esta tesis abordamos el problema del reconocimiento de habla cuando la señal de voz es transmitida a través de un canal inalámbrico. Las distorsiones que este tipo de entornos introducen en los parámetros de entrada son más difíciles de modelar que en el caso de tener ruidos aditivos y, por ello, su efecto se ha estudiado de forma experimental en el dominio del espectro de modulación. A la vista de nuestras observaciones, proponemos filtrar paso-banda la evolución temporal de los parámetros para aumentar la robustez del sistema reconocedor. Nuestra propuesta se evalúa para dos parametrizaciones bajo canales con diferentes tasas de error de bit (Bit Error Rate, BER) típicas de este tipo de comunicaciones inalámbricas: por un lado, filtramos paso-banda la evolución temporal de los parámetros LP-MCC y, por otro, sustituimos el filtro paso-banda RASTA-PLP por otro cuya sección paso bajo es más abrupta. Nuestros resultados encuentran mejores resultados con las secuencias filtradas. Finalmente, aplicamos la técnica BD-HMM para reducir el impacto de los outliers en este tipo de entornos inalámbricos. Nuestros resultados muestran que BD-HMM introduce importantes mejoras para canales con altas tasas de error de bit. ____________________________________________In this Ph.D. Thesis we address the problem of robust speech recognition.We start studying the effects of additive noises. We show that one of the causes contributing to the loss of performance in presence of noise is the fact that conventional recogniser take into consideration feature values that are actually outliers.We propose a method that we call Bounded-Distance HMM (BD-HMM) to mitigate the outlier contribution to the recogniser decision. Since BD-HMM just deals with outliers, leaving the remaining features unaltered, we suggest to combine it with other techniques that work on all the features. In particular, we propose to use spectral subtraction as feature enhancement technique, since it complements BD-HMM well. As we prove in the Thesis, spectral subtraction introduces some artifacts that cause a larger number of outliers that can be easily countered by BD-HMM. Our experimental results show that the combination of these techniques generally outperforms both BD-HMM and spectral subtraction individually. Furthermore, the obtained improvements, especially for low and medium SNRs, are generally larger than the sum of the improvements individually obtained by BD-HMM and spectral subtraction. On the other hand, the spectral subtraction-based estimates of the original parameters generate certain level of uncertainty that is not usually taken into account by the decoding algorithm. This Thesis takes into consideration this uncertainty in the recogniser for a specific type of features: the Frequency Filtered parameterization. Moreover, as this parameterization remains in the log-frequency domain, the proposed method admits a simple interpretation as a spectral weighting method that assigns more importance to the most reliable spectral components. Our results show the convenience of incorporating this information in the decoding process. Finally, in this Thesis we tackle the problem of speech recognition when wireless speech communication systems are involved. The distortions caused by this environment are more difficult to model analytically than the ones caused by additive noises. Thus, we experimentally study their effects on the feature spectra and we propose to band-pass filter the recognition features to improve the ASR performance. We have evaluated our proposal in two configurations at different Bit Error Rates (BER) typical of these channels: band-pass filtering the LP-MFCC parameters and a modification of the RASTA-PLP using a sharper low-pass section. Both filtered parameterizations perform consistently better than the unfiltered ones. Additionally, we remove the impact of the outliers by applying BD-HMM, what results in larger improvements for high BER channels

Band-pass filtering of the time sequences of spectral parameters for robust wireless speech recognition

In this paper we address the problem of automatic speech recognition when wireless speech communication systems are involved. In this context, three main sources of distortion should be considered: acoustic environment, speech coding and transmission errors. Whilst the first one has already received a lot of attention, the last two deserve further investigation in our opinion. We have found out that band-pass filtering of the recognition features improves ASR performance when distortions due to these particular communication systems are present. Furthermore, we have evaluated two alternative configurations at different bit error rates (BER) typical of these channels: band-pass filtering the LP-MFCC parameters or a modification of the RASTA-PLP using a sharper low-pass section perform consistently better than LP-MFCC and RASTA-PLP, respectively.Publicad

The synergy between bounded-distance HMM and spectral subtraction for robust speech recognition

Additive noise generates important losses in automatic speech recognition systems. In this paper, we show that one of the causes contributing to these losses is the fact that conventional recognisers take into consideration feature values that are outliers. The method that we call bounded-distance HMM is a suitable method to avoid that outliers contribute to the recogniser decision. However, this method just deals with outliers, leaving the remaining features unaltered. In contrast, spectral subtraction is able to correct all the features at the expense of introducing some artifacts that, as shown in the paper, cause a larger number of outliers. As a result, we find that bounded-distance HMM and spectral subtraction complement each other well. A comprehensive experimental evaluation was conducted, considering several well-known ASR tasks (of different complexities) and numerous noise types and SNRs. The achieved results show that the suggested combination generally outperforms both the bounded-distance HMM and spectral subtraction individually. Furthermore, the obtained improvements, especially for low and medium SNRs, are larger than the sum of the improvements individually obtained by bounded-distance HMM and spectral subtraction.Publicad

Kinematic analysis of throwing between right and left top member in water-polo

En el presente artículo se han analizado las diferencias en la velocidad de lanzamiento en waterpolo entre el miembro superior derecho e izquierdo. Participaron 16 jugadores (24.25±4.8 años, 1.97±1.9 m, 75.33±7.1 Kg) los cuales realizaron primero un calentamiento, tanto general como específico, para posteriormente realizar 3 lanzamientos alternando el brazo ejecutor. El cálculo de la velocidad de lanzamiento se realizó mediante fotogrametría 2D. Los resultados obtenidos indican que existen diferencias significativas (p<0.001) en la velocidad de lanzamiento entre el miembro superior derecho e izquierdo (X = 18.66 ± 3.047 m/s y X = 12.06 ± 1.476 m/s, respectivamente). También encontramos una alta correlación (p<0.01) entre la edad y las diferencias en el lanzamiento entre ambos brazos (r = 0.63)

Application of edible nanolaminate coatings with antimicrobial extract of Flourensia cernua to extend the shelf-life of tomato (Solanum lycopersicum L.) fruit

Supplementarymaterialrelatedtothisarticlecanbefound,inthe online version, at doi:https://doi.org/10.1016/j.postharvbio.2018.12. 008.Edible coatings have potential to reduce postharvest losses of fruit such as tomato. In this study, the effects of nanolaminate coatings incorporated with extracts of Flourensia cernua, an endemic plant of the arid and semi-arid regions of Mexico, has been investigated. Ethanol extracts of F. cernua (FcE) were prepared and incorporated into polyelectrolyte solutions of alginate and chitosan. The nanolaminates were characterized by determining the zeta potential, contact angle and water vapor and oxygen permeabilities. Shelf-life analyses (20°C for 15 d) were carried out with uncoated fruit (UCF), nanolaminate coating (NL) and nanolaminate coating with FcE (NL+FcE). Physicochemical analyses, gas exchange rates of O2 and CO2 and ethylene production, as well as microbiological analyses of treated fruit were measured. Zeta potential and contact angle measurements confirmed the successful assembly of successive nanolayers of alginate and chitosan, as well as those with F. cernua. The nanolaminate coatings resulted in decreased permeabilities to water and O2. The best treatment of NL+FcE, extended the shelf-life of fruit by reducing weight loss and microbial growth, reducing gas exchange and ethylene production, and maintaining firmness and color. The NL+FcE treatment are an alternative to extend the shelf-life of tomato fruit.Author E. de J. Salas-Méndez thanks Mexican Science and Technology Council (CONACYT, Mexico) for PhD fellowship support. Authors want to thank PhD Zlatina Genisheva for the proof reading of the manuscript and suggestions to the same; also, to:MaríaGuadalupe Moreno Esquivel, Edith E. Chaires Colunga, Olga L. Solís Hernández and M. Leticia Rodríguez González of the Phytochemistry Laboratory from Universidad Autónoma Agraria Antonio Narro, for their assistance in obtaining extracts and chemical composition.info:eu-repo/semantics/publishedVersio

Desigualdad en educación y desarrollo profesional de los docentes que trabajan con alumnos, centros y zonas en riesgo de sufrir procesos de exclusión

Celebrado en Granada los días 25, 26 y 27 de septiembre de 2003.Hablar de formación del profesor en contextos de desigualdad –dado que ésta profesionalización es un proceso continuo a lo largo de toda su trayectoria profesional–, supone invariablemente hablar de un modelo de profesor, de interacción didáctica, de educación... De partida, nos plateábamos que existía un modelo de profesor, de socialización en la zona y de desarrollo profesional en estas circunstancias muy particulares. Por lo que parece relevante comprender cómo sienten los profesores el ejercicio de su profesión en estos contextos, cómo varían sus necesidades y orientaciones vitales y qué opinan ellos como fundamental para ajustarse a y transformar la realidad en la que trabajan; pero también contextualizar y atemperar sus opiniones y relatos de experiencia con las de otros agentes de la comunidad

A genome-wide association study follow-up suggests a possible role for PPARG in systemic sclerosis susceptibility

Introduction: A recent genome-wide association study (GWAS) comprising a French cohort of systemic sclerosis (SSc) reported several non-HLA single-nucleotide polymorphisms (SNPs) showing a nominal association in the discovery phase. We aimed to identify previously overlooked susceptibility variants by using a follow-up strategy.&lt;p&gt;&lt;/p&gt; Methods: Sixty-six non-HLA SNPs showing a P value &#60;10-4 in the discovery phase of the French SSc GWAS were analyzed in the first step of this study, performing a meta-analysis that combined data from the two published SSc GWASs. A total of 2,921 SSc patients and 6,963 healthy controls were included in this first phase. Two SNPs, PPARG rs310746 and CHRNA9 rs6832151, were selected for genotyping in the replication cohort (1,068 SSc patients and 6,762 healthy controls) based on the results of the first step. Genotyping was performed by using TaqMan SNP genotyping assays. Results: We observed nominal associations for both PPARG rs310746 (PMH = 1.90 × 10-6, OR, 1.28) and CHRNA9 rs6832151 (PMH = 4.30 × 10-6, OR, 1.17) genetic variants with SSc in the first step of our study. In the replication phase, we observed a trend of association for PPARG rs310746 (P value = 0.066; OR, 1.17). The combined overall Mantel-Haenszel meta-analysis of all the cohorts included in the present study revealed that PPARG rs310746 remained associated with SSc with a nominal non-genome-wide significant P value (PMH = 5.00 × 10-7; OR, 1.25). No evidence of association was observed for CHRNA9 rs6832151 either in the replication phase or in the overall pooled analysis.&lt;p&gt;&lt;/p&gt; Conclusion: Our results suggest a role of PPARG gene in the development of SSc

Severe manifestations of SARS-CoV-2 in children and adolescents: from COVID-19 pneumonia to multisystem inflammatory syndrome: a multicentre study in pediatric intensive care units in Spain

Background Multisystem inflammatory syndrome temporally associated with COVID-19 (MIS-C) has been described as a novel and often severe presentation of SARS-CoV-2 infection in children. We aimed to describe the characteristics of children admitted to Pediatric Intensive Care Units (PICUs) presenting with MIS-C in comparison with those admitted with SARS-CoV-2 infection with other features such as COVID-19 pneumonia. Methods A multicentric prospective national registry including 47 PICUs was carried out. Data from children admitted with confirmed SARS-CoV-2 infection or fulfilling MIS-C criteria (with or without SARS-CoV-2 PCR confirmation) were collected. Clinical, laboratory and therapeutic features between MIS-C and non-MIS-C patients were compared. Results Seventy-four children were recruited. Sixty-one percent met MIS-C definition. MIS-C patients were older than non-MIS-C patients (p = 0.002): 9.4 years (IQR 5.5-11.8) vs 3.4 years (IQR 0.4-9.4). A higher proportion of them had no previous medical history of interest (88.2% vs 51.7%, p = 0.005). Non-MIS-C patients presented more frequently with respiratory distress (60.7% vs 13.3%, p < 0.001). MIS-C patients showed higher prevalence of fever (95.6% vs 64.3%, p < 0.001), diarrhea (66.7% vs 11.5%, p < 0.001), vomits (71.1% vs 23.1%, p = 0.001), fatigue (65.9% vs 36%, p = 0.016), shock (84.4% vs 13.8%, p < 0.001) and cardiac dysfunction (53.3% vs 10.3%, p = 0.001). MIS-C group had a lower lymphocyte count (p < 0.001) and LDH (p = 0.001) but higher neutrophil count (p = 0.045), neutrophil/lymphocyte ratio (p < 0.001), C-reactive protein (p < 0.001) and procalcitonin (p < 0.001). Patients in the MIS-C group were less likely to receive invasive ventilation (13.3% vs 41.4%, p = 0.005) but were more often treated with vasoactive drugs (66.7% vs 24.1%, p < 0.001), corticosteroids (80% vs 44.8%, p = 0.003) and immunoglobulins (51.1% vs 6.9%, p < 0.001). Most patients were discharged from PICU by the end of data collection with a median length of stay of 5 days (IQR 2.5-8 days) in the MIS-C group. Three patients died, none of them belonged to the MIS-C group. Conclusions MIS-C seems to be the most frequent presentation among critically ill children with SARS-CoV-2 infection. MIS-C patients are older and usually healthy. They show a higher prevalence of gastrointestinal symptoms and shock and are more likely to receive vasoactive drugs and immunomodulators and less likely to need mechanical ventilation than non-MIS-C patients