Bootstrap-based procedures for inference in nonparametric receiver-operating characteristic curve regression analysis

Prior to using a diagnostic test in a routine clinical setting, the rigorous evaluation of its diagnostic accuracy is essential. The receiver-operating characteristic curve is the measure of accuracy most widely used for continuous diagnostic tests. However, the possible impact of extra information about the patient (or even the environment) on diagnostic accuracy also needs to be assessed. In this paper, we focus on an estimator for the covariate-specific receiver-operating characteristic curve based on direct regression modelling and nonparametric smoothing techniques. This approach defines the class of generalised additive models for the receiver-operating characteristic curve. The main aim of the paper is to offer new inferential procedures for testing the effect of covariates on the conditional receiver-operating characteristic curve within the above-mentioned class. Specifically, two different bootstrap-based tests are suggested to check (a) the possible effect of continuous covariates on the receiver-operating characteristic curve and (b) the presence of factor-by-curve interaction terms. The validity of the proposed bootstrap-based procedures is supported by simulations. To facilitate the application of these new procedures in practice, an R-package, known as npROCRegression, is provided and briefly described. Finally, data derived from a computer-aided diagnostic system for the automatic detection of tumour masses in breast cancer is analyse

Bootstrap-based procedures for inference in nonparametric ROC regression analysis

Before the use of a diagnostic test in a routine clinical setting, the rigorous evaluation of its diagnostic accuracy is an essential step. The receiver operating characteristic (ROC) curve is the measure of accuracy most widely used for continuous diagnostic tests. However, the possible impact of extra information about the patient (or even the environment) on diagnostic accuracy needs to be also assessed. In this paper, attention is focused on an estimator for the covariate-specific ROC curve based on direct regression modelling and nonparametric smoothing techniques. This approach defines the class of generalized additive models for the ROC curve (ROC-GAM). The main aim of the paper is to offer new inferential procedures for testing the effect of co- variates over the conditional ROC curve within the ROC-GAM context. Specifically, two different bootstrap-based tests are suggested to check (a) the possible effect of continuous covariates on the ROC curve; and (b) the presence of factor-by-curve interaction terms. The validity of the proposed bootstrap-based procedures is supported by simulations. To facilitate the application of these new procedures in practice, an R-package, known as npROCRegression, is provided and briefly described. Finally, data derived from a computed-aided diagnostic (CAD) system for the automatic detection of tumour masses in breast cancer is analysed

Extrusión del componente plástico de la copa acetabular sin luxación protésica: a propósito de un caso

Se present a un caso de extrusión del component e plástic o (polietileno) ocurrido en el transcurso del primer me s del postoperatorio en un pacient e que había sufrido un recambio del component e acetabular. Se destaca el hecho de que cursase de forma asintomática y de que no se acompañase de luxación de la prótesis.A case of disassembly of the polyethylene component of the acetabular cup acurred in a patient one mouth after revision surgery for loosening of a screwed acetabular cup is reported. Special emphasis is made in the asyntomati c clinic and on the no association with dislocation of the femoral component

Structural properties of various sodium thiogermanate glasses through DFT-based molecular dynamics simulations

We present a study of the structural properties of (x)Na$_2$S-(1-x)GeS$_2$ glasses through DFT-based molecular dynamics simulations, at different sodium concentrations ($0<x<0.5$). We computed the radial pair correlation functions as well as the total and partial structure factors. We also analyzed the evolution of the corner- and edge-sharing intertetrahedral links with the sodium concentration and show that the sodium ions exclusively destroy the former. With the increase of the sodium concentration the ``standard'' FSDP disappears and a new pre-peak appears in the structure factor which can be traced back in the Na-Na partial structure factor. This self organization of the sodium ions is coherent with Na-rich zones that we find at high modifier concentration.Comment: 9 pages, 7 figures; to be published in Phys. Rev.

Academic Success and Student Satisfaction with University Teaching

This study uses surveys to assess student academic success in relation to the teaching activity of the University staff. The main goal is to test how the student’s degree of satisfaction of with their teachers can be considered dependent on the success the student obtains in each subject. The results show that the students are more satisfied with their teaching when they have a higher rate of success, although in some optional courses, the degree of satisfaction diminishes with the higher rate of success. The course expectations, when defined by the difference between achievement and success, impact the student satisfaction with the teaching

Mandibular advancement devices in the treatment of obstructive sleep apnea syndrome

La apnea del sueño es un trastorno respiratorio, con consecuencias no deseables para la salud, que ocurre durante el sueño cuando se obstruyen o colapsan las vías aéreas superiores. El fenómeno es bien conocido clínicamente, con diagnosis y tratamientos médicos contrastados, pero no existe una metodología sencilla ni los instrumentos y técnicas de análisis necesarias para conocer y valorar cualitativa y cuantitativamente la respuesta física y clínica de una actuación mandibular concreta. En este trabajo se muestra como las técnicas digitales de tratamiento de imágenes, la dinámica de fluidos y la implementación de criterios ingenieriles de diseño importados de otros campos de actividad permiten, a partir de unas imágenes médicas convencionales, establecer una metodología de análisis sencilla útil clínicamente para decidir las actuaciones, de presión o mecánicas, mandibulares más convenientes. La metodología se aplica a un paciente que sufre el síndrome y se estudia el efecto de un dispositivo mandibular (DAM® ), especialmente innovador, premiado científica y empresarialmente en varias ocasiones, que por medio de un avance de la mandíbula, variable y distinto para cada paciente según las necesidades clínicas, provoca una apertura significativa de las vías aéreas superiores.Obstructive sleep apnea syndrome (OSAS) consists in the occurrence of recurrent episodes of airflow limitation during sleep, with undesirable consequences for the health. The phenomenon is well known from a medical point of view (prognosis, diagnosis and treatment), but there is not a methodology or analysis tools for the quantification of the clinical response using Mandibular Advancement Devices (MAD). This paper shows how combining image processing, fluid dynamics and engineering design criteria, imported from other fields, allow to establish a simple analysis method clinically useful to decide the more convenient positioning of the MAD based on the pressure or mechanical movement of the jaw. This methodology is applied to a patient suffering OSAS which the objective to evaluate the changes provoked in the upper-airways due to an innovative mandibular device.Peer Reviewe

Temperature Sensor Based on Colloidal Quantum Dots PMMA Nanocomposite Waveguides

In this paper, integrated temperature sensors based on active nanocomposite planar waveguides are presented. The nanocomposites consist of cadmium selenide (CdSe) and cadmium telluride (CdTe) quantum dots (QDs) embedded in a polymethylmethacrylate (PMMA) matrix. When the samples are heated in a temperature range from 25$^{circ}{rm C}$ to 50 $^{circ}{rm C}$, the waveguided photoluminescence of QDs suffers from a strong intensity decrease, which is approximately quadratic dependent on temperature. Moreover, the wavelength peak of the waveguided emission spectrum of CdTe-PMMA shows a blue shift of 0.25 ${rm nm}/^{circ}{rm C}$, whereas it remains constant in the case of CdSe-PMMA. A temperature resolution of 0.1$^{circ}{rm C}$ is obtained. QD waveguides have great potential for the development of photonic sensors because of their integration, multiplexing, and roll-to-roll fabrication capabilities.Manuscript received February 21, 2012; revised May 8, 2012; accepted July 18, 2012. Date of publication July 24, 2012; date of current version August 9, 2012. This work was supported in part by the Spanish MICINN and Generalitat Valenciana under Grant TEC-2011-06756-C03-03 and Grant PROMETEO/2009/074, the Plan Nacional I + D under Project TEC2011-29120-C05-01 and Project TEC2011-29120-C05-05, and the Infraestructura FEDER UPVOV08-3E-008. The associate editor coordinating the review of this paper and approving it for publication was Prof. E. H. Yang.Bueno Martínez, A.; Suárez Álvarez, I.; Abargues, R.; Sales Maicas, S.; J. MARTÍNEZ-PASTOR (2012). Temperature Sensor Based on Colloidal Quantum Dots PMMA Nanocomposite Waveguides. IEEE Sensors Journal. 12(10):3069-3074. https://doi.org/10.1109/JSEN.2012.2210037S30693074121

Diminished emotional expression in schizophrenia: An interdisciplinary approach based on behavioral interventions

Resumen tomado de la publicaciónExpresión emocional disminuida en la esquizofrenia: un abordaje interdisciplinar basado en intervenciones conductuales. Antecedentes: los síntomas negativos representan la principal causa de discapacidad en la esquizofrenia, habiendo sido agrupados recientemente en dos dimensiones: avolición y expresión emocional disminuida, que incluye el aplanamiento afectivo y la alogia. El objetivo del estudio fue explorar la respuesta de estos dos síntomas a un conjunto de intervenciones conductuales basadas en el manejo de contingencias en un contexto interdisciplinario. Método: se monitorizaron conductas de interés y realizaron medidas pre y post a 9 participantes con esquizofrenia negativa persistente ingresados en dispositivos de rehabilitación. El programa incluyó 12 sesiones grupales dobles dirigidas a trabajar la expresión facial y la comunicación verbal, y un plan de cuidados para fortalecer y generalizar estas conductas. Resultados: se obtuvieron diferencias relevantes en la expresión facial, que fueron menos claras para la alogia. La evaluación clínica mediante la PANSS-N no obtuvo diferencias notables a nivel de grupo, pero sí la valoración mediante indicadores NOC. Conclusiones: aunque difíciles de modificar, los síntomas negativos no son insensibles a la influencia de intervenciones conductuales. Resulta necesario potenciar intervenciones psicológicas específicas que aborden estos síntomas como un foco prioritario de atención y cuidado, considerando el papel crucial del contexto en su evolución.Universidad de Oviedo. Biblioteca de Psicología; Plaza Feijoo, s/n.; 33003 Oviedo; Tel. +34985104146; Fax +34985104126; [email protected]

Differential Behavior Between Isolated and Aggregated Rabbit Auricular Chondrocytes on Plastic Surfaces

A knowledge of the behavior of chondrocytes in culture is relevant for tissue engineering. Chondrocytes dedifferentiate to a fibroblast-like phenotype on plastic surfaces. Dedifferentiation is reversible if these cells are then cultured in suspension. In this report a description is given of how when chondrocyte aggregates formed in suspension are next seeded on plastic, most of them attach as round or polygonal cells. This morphological differentiation, with synthesis of type II collagen, is stable for long culture periods. This simple method can be of use as a model for studies of chondrocyte behavior on plastic. The results indicate that in addition to culture conditions, such as cell isolation method or cell density, chondrocyte behavior on plastic depends on the presence of aggregates

Effects of Extracellular Matrix on the Morphology and Behaviour of Rabbit Auricular Chondrocytes in Culture

Isolated chondrocytes dedifferentiate to a fibroblast-like shape on plastic substrata and proliferate extensively, but rarely form nodules. However, when dissociation is not complete and some cartilage remnants are included in the culture, proliferation decreases and cells grow in a reticular pattern with numerous nodules, which occasionally form small cartilage-like fragments. In an attempt to reproduce this stable chondrogenic state, we added a cartilage protein extract, a sugar extract, and hyaluronan to the medium of previously dedifferentiated chondrocytes. When protein extract was added, many cartilaginous nodules appeared. Hyaluronan produced changes in cell phenotype and behaviour, but not nodule formation. Protein extract has positive effects on the differentiation of previously proliferated chondrocytes and permits nodule formation and the extensive production of type-II collagen. A comparison with incompletely dissociated chondrocyte cultures suggests that the presence of some living cells anchored to their natural extracellular matrix provides some important additional factors for the phenotypical stability of chondrocytes on plastic surfaces. In order to elucidate if it is possible that the incidence of apoptosis is related to the results, we also characterized the molecular traits of apoptosis