Supervisió i detecció d'activitats d'una persona mitjançant sensors inercials vestibles

El marc de referència general del projecte de màster realitzat és el disseny i anàlisi d’una solució tecnològica completa per a la supervisió constant i de la salut i detecció d'anomalies de les persones. Dins d’aquest marc de referència global, el treball específic desenvolupat s’ha basat en validar el funcionament d’un sensor inercial per a la detecció i supervisió de certes disfuncions que es produeixen de manera habitual en l'activitat diària de moltes persones, principalment d’edat avançada, i que en qualsevol cas són molt freqüents en la majoria de pacients que requereixen d’un cert grau de supervisió. Una vegada validat el funcionament del mòdul sensor, aquesta tecnologia ha de significar el primer pas per arribar a crear una arquitectura de supervisió de salut de les persones que permeti disposar d’una informació constant i ubiqua del pacient. Per al desenvolupament de la investigació s’ha utilitzat un sensor inercial Xsens MT-9 que disposa d’acceleròmetres, giròscops i magnetòmetres de 3 dimensions amb sortides calibrades. A més, el sensor es subministra amb una sèrie de llibreries que ofereixen una posada en marxa simplificada de l’experimentació i anàlisi de senyals. S’ha optat per realitzar l'anàlisi experimental sobre MATLAB, la qual ha de permetre realitzar la detecció i la supervisió d’una persona en temps real. Des del punt de vista de la supervisió, els algorismes implementats analitzen la marxa i l’equilibri de l’individu tot detectant, en un primer moment, els moviments laterals involuntaris i la despesa energètica. Els moviments laterals involuntaris denoten canvis en l’estat de salut, l’augment en el risc de caigudes o simplement són signe d’un deteriorament de la salut de la persona. El seguiment de la despesa energètica permet observar l'augment o reducció de l'activitat de la persona que vesteix el sensor. Aquesta supervisió ha de generar una història per tal que pugui ser analitzada per un centre mèdic i permeti, a partir d’ella, fer una futura diagnosi. A més a més, des del punt de vista de la detecció, l’algorisme permet la detecció de caigudes i, per tant, podria ser utilitzat per generar una alarma a serveis d’urgència mèdica. Una vegada validat aquest sistema, es disposa d’un punt de partida òptim per arribar a construir, de manera escalable, una arquitectura de supervisió de la salut. Per una banda es poden utilitzar més mòduls basats en els mateixos sistemes inercials que disposa el sensor comercial, però implementant una comunicació sense fils, però també es poden incorporar nous tipus de sensors, com ara d’electrocardiograma, de pressió arterial, etc. D’altra banda el fet de disposar de més sensors pot facilitar amb el desenvolupament dels algorismes corresponents, la detecció d’informació addicional, com ara, l’activitat motriu de la persona, que a més, permet que la diagnosi es faci depenent de la tasca que la persona realitza en cada moment. Finalment s’ha de construir l’arquitectura ubiqua, és a dir, que sense intervenció del pacient, la informació captada i analitzada per l’arquitectura personal sigui transmesa en temps real al món exterior: centres d’urgències en cas de detecció d’una situació d’emergència o centres mèdics que recullin la informació històrica de l’individu

Single subthalamic nucleus deep brain stimuli inhibit the blink reflex in Parkinson's disease patients

© The Author (2006). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved.The disordered output from the basal ganglia to the pontine tegmentum nuclei is considered responsible for a number of abnormalities in brainstem reflexes in patients with Parkinson's disease. One of the most conspicuous of these abnormalities is the reduced inhibition of the blink reflex by a prepulse stimulus. The circuit of prepulse inhibition involves structures and fibre groups that can be reached by stimuli applied through the electrodes implanted in the subthalamic nucleus for deep brain stimulation (STNDBS). In seven Parkinson's disease patients we examined whether single STNDBS induced prepulse effects on the blink reflex and how they compared with the effects induced by single auditory and somatosensory stimuli. Prepulse inhibition was determined by measuring the percentage inhibition induced in the R2 component of the orbicularis oculi response to supraorbital nerve stimuli. The inter-stimuli intervals (ISI) between the prepulse and the supraorbital nerve stimuli were 0 to 30 ms and 100 ms for single STNDBS and 100 ms for auditory and somatosensory modalities. The results obtained with acoustic and somatosensory stimuli were compared with those obtained from a group of 20 age-matched healthy subjects. Single STNDBS induced significant inhibition of the R2 in all patients at ISIs between 10 and 30 ms, with a mean percentage inhibition of 94% at the ISI of 30 ms. On the contrary, significant inhibition by auditory or somatosensory stimuli was induced in only two out of the seven patients. The mean percentage inhibition at the ISI of 100 ms was 37% for auditory and 40% for somatosensory stimuli, well below reference limits for prepulse inhibition in control subjects (61%). Single STNDBS induces significant prepulse inhibition of the blink reflex in Parkinson's disease patients who have abnormally reduced auditory and somatosensory prepulse effects. This finding helps define the prepulse circuit in humans and the eventual site of its dysfunction in Parkinson's disease.This work was in part accomplished thanks to grant P1040970 from FIS. J.C. has received a scholarship from the non-government Calouste Gulbenkian Foundationinfo:eu-repo/semantics/publishedVersio

Voronoi-based space partitioning for coordinated multi-robot exploration

Recent multi-robot exploration algorithms usually rely on occupancy grids as their core world representation. However, those grids are not appropriate for environments that are very large or whose boundaries are not well delimited from the beginning of the exploration. In contrast, polygonal representations do not have such limitations. Previously, the authors have proposed a new exploration algorithm based on partitioning unknown space into as many regions as available robots by applying K-Means clustering to an occupancy grid representation, and have shown that this approach leads to higher robot dispersion than other approaches, which is potentially beneficial for quick coverage of wide areas. In this paper, the original K-Means clustering applied over grid cells, which is the most expensive stage of the aforementioned exploration algorithm, is substituted for a Voronoi-based partitioning algorithm applied to polygons. The computational cost of the exploration algorithm is thus significantly reduced for large maps. An empirical evaluation and comparison of both partitioning approaches is presented.This work is partially supported by the Government of Spain under MCYT DPI2004-07993-C03-03. Ling Wu is supported by a FPI scholarship from the Spanish Ministry of Education and Science

Differential responses of spinal motoneurons to fatigue induced by short-lasting repetitive and isometric tasks

[Abstract] Compared to isometric activities, the neural basis of fatigue induced by repetitive tasks has been scarcely studied. Recently, we showed that during short-lasting repetitive tasks at the maximal possible rate (finger tapping for 10 and 30 s), tapping rate and maximal voluntary contraction (MVC) force decrease at the end of finger tapping. We also observed larger silent periods (SP) induced by transcranial magnetic stimulation during MVC post finger tapping. However, if SP were induced by cervicomedullary stimulation (CMS) they remained unchanged. This suggested a supraspinal origin of fatigue for repetitive tasks. Nevertheless, CMS SP only partially explore spinal excitability; therefore, to evaluate a spinal origin of fatigue it is essential to know the features of the CMS-evoked potentials (CMEP). Herein, we evaluated (n = 15) the amplitude of the CMEP during MVC executed immediately (no gap) after a short-lasting finger tapping task; we also evaluated the compound muscle action potential (CMAP) so that the amplitude of the CMEP was expressed as a function of the CMAP amplitude. Indices of fatigue obtained during finger tapping were compared with those obtained during short-lasting maximal isometric tasks. While indices of excitability increased initially in both tasks, they decreased with the isometric task only when the task was prolonged to 30 s. We suggest that the inability to maintain increased levels of spinal excitability during task execution is a neurophysiological mark of fatigue. Our results suggest that the origin of fatigue induced by brief and fast repetitive tasks is not spinal.Galicia. Consellería de Educación; 2007/000140-

Reply to the commentary on Luis et al. "spontaneous plugging of the horizontal semicircular canal with reversible canal dysfunction and recovery of vestibular evoked myogenic potentials"

info:eu-repo/semantics/acceptedVersio

Integrative analysis of a cancer somatic mutome

BACKGROUND: The consecutive acquisition of genetic alterations characterizes neoplastic processes. As a consequence of these alterations, molecular interactions are reprogrammed in the context of highly connected and regulated cellular networks. The recent identification of the collection of somatically mutated genes in breast tumors (breast cancer somatic "mutome") allows the comprehensive study of its function and organization in complex networks. RESULTS: We analyzed functional genomic data (loss of heterozygosity, copy number variation and gene expression in breast tumors) and protein binary interactions from public repositories to identify potential novel components of neoplastic processes, the functional relationships between them, and to examine their coordinated function in breast cancer pathogenesis. This analysis identified candidate tumor suppressors and oncogenes, and new genes whose expression level predicts survival rate in breast cancer patients. Mutome network modeling using different types of pathological and healthy functional relationships unveils functional modules significantly enriched in genes or proteins (genes/proteins) with related biological process Gene Ontology terms and containing known breast cancer-related genes/proteins. CONCLUSION: This study presents a comprehensive analysis of the breast somatic mutome, highlighting those genes with a higher probability of playing a determinant role in tumorigenesis and better defining molecular interactions related to the neoplastic process