1000 resultados para Virtual MIMO


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This thesis seeks to answer, if communication challenges in virtual teams can be overcome with the help of computer-mediated communication. Virtual teams are becoming more common work method in many global companies. In order for virtual teams to reach their maximum potential, effective asynchronous and synchronous methods for communication are needed. The thesis covers communication in virtual teams, as well as leadership and trust building in virtual environments with the help of CMC. First, the communication challenges in virtual teams are identified by using a framework of knowledge sharing barriers in virtual teams by Rosen et al. (2007) Secondly, the leadership and trust in virtual teams are defined in the context of CMC. The performance of virtual teams is evaluated in the case study by exploiting these three dimensions. With the help of a case study of two virtual teams, the practical issues related to selecting and implementing communication technologies as well as overcoming knowledge sharing barriers is being discussed. The case studies involve a complex inter-organisational setting, where four companies are working together in order to maintain a new IT system. The communication difficulties are related to inadequate communication technologies, lack of trust and the undefined relationships of the stakeholders and the team members. As a result, it is suggested that communication technologies are needed in order to improve the virtual team performance, but are not however solely capable of solving the communication challenges in virtual teams. In addition, suitable leadership and trust between team members are required in order to improve the knowledge sharing and communication in virtual teams.

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OBJETIVO: Analisar a reprodutibilidade intra-observador da ultra-sonografia tridimensional (US3D) real com a US virtual, nas modalidades multiplanar e volumétrica. MATERIAIS E MÉTODOS: Foram examinados, prospectivamente, 132 blocos provenientes de 44 avaliações de 26 conceptos. Dezoito conceptos tinham idade gestacional ecográfica de oito semanas a oito semanas e seis dias, e 26 tinham de dez semanas a dez semanas e seis dias. Realizou-se a US3D, analisando-se: comprimento cabeça-nádega, saco gestacional, saco amniótico, translucência nucal, conduto onfalomesentérico, vesícula vitelínica, membros superiores, membros inferiores, distinção cabeça-tórax, perfil da face, coronal da face, implantação das orelhas, perfil da coluna, coronal da coluna, parede abdominal fechada. Foram obtidos três blocos por concepto para posterior realização da US virtual. A análise estatística foi feita utilizando-se o teste t de Student, o teste de McNemar e o kappa. RESULTADOS: No grupo I, a avaliação ultra-sonográfica 3D real multiplanar versus 3D virtual multiplanar, na análise das variáveis contínuas, evidenciou diferença significativa para todas. Na avaliação das variáveis categóricas, evidenciou-se que todas não apresentaram diferença significativa. No grupo II, a avaliação ultra-sonográfica 3D real volumétrica versus 3D virtual volumétrica demonstrou diferença significativa apenas para a variável implantação de orelhas. Os resultados das análises das variáveis categóricas evidenciaram concordância para a maioria das variáveis analisadas em ambos os grupos. CONCLUSÃO: Há reprodutibilidade intra-observador da US3D com a modalidade virtual, multiplanar e volumétrica.

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La emergencia y dinámica del Elearning, en los actuales escenarios de educación superior, evidencia una importante transformación acontecida en el marco de la sociedad de la información: la utilización de las TIC en los procesos de construcción del conocimiento. Este cambio ha ido de la mano, en primer lugar, de la mejora en la calidad y la oferta formativa existente, una oferta que ha buscado ser más inclusiva y representativa de las actuales demandas sociales. Y en segundo lugar, se trata de una modalidad que ha intentado adaptarse a las actuales características del estudiantado digital y del digitalizado (Prensky, 2006), cuyo rol en los proceso de enseñanza, tiende a ser más activo que en los modelos de formación tradicional. El presente artículo, se focaliza en esta segunda dimensión, analizando como el Elearning intenta ser un elemento de mediación entre las transformaciones actuales que se dan en la educación superior y la emergencia de un nuevo estudiantado virtual, cada vez más activo y autónomo.

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The aim of this article was to study the effect of virtual-reality exposure to situations that are emotionally significant for patients with eating disorders (ED) on the stability of body-image distortion and body-image dissatisfaction. A total of 85 ED patients and 108 non-ED students were randomly exposed to four experimental virtual environments: a kitchen with low-calorie food, a kitchen with high-calorie food, a restaurant with low-calorie food, and a restaurant with high-calorie food. In the interval between the presentation of each situation, body-image distortion and body-image dissatisfaction were assessed. Several 2 x 2 x 2 repeated measures analyses of variance (high-calorie vs. low-calorie food x presence vs. absence of people x ED group vs. control group) showed that ED participants had significantly higher levels of body-image distortion and body dissatisfaction after eating high-calorie food than after eating low-calorie food, while control participants reported a similar body image in all situations. The results suggest that body-image distortion and body-image dissatisfaction show both trait and state features. On the one hand, ED patients show a general predisposition to overestimate their body size and to feel more dissatisfied with their body image than controls. On the other hand, these body-image disturbances fluctuate when participants are exposed to virtual situations that are emotionally relevant for them.

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La comunicación que se presenta, muestra cómo se lleva a cabo la gestión de los procesos técnicos de los libros electrónicos en la Biblioteca Virtual (en adelante BV) de la Universitat Oberta de Catalunya (en adelante UOC). La BV está integrada en el Campus Virtual y en las aulas virtuales de la Universidad. La principal particularidad de la docencia en la UOC se encuentra en el hecho de que se realiza, en su totalidad, por medio de un Campus Virtual.La BV de la UOC pone especial énfasis en la adquisición de libros digitales para mejorar el acceso de los usuarios a sus recursos y colecciones en una universidad con un modelo de aprendizaje caracterizada por su virtualidad (el 13 de abril de 2011, el Consejo de Gobierno acordó priorizar la adquisición de documentos en formato electrónico). La irrupción de los libros electrónicos en la BV ha comportado una revisión de los procesos técnicos, de manera que los circuitos de adquisición, catalogación y gestión de la colección digital trabajen de forma coordinada. En primer lugar, se describe el entorno en el que se adquieren y se utilizan los libros electrónicos, los distintos escenarios de adquisición y modelos de compra con los que se puede encontrar la BV de la UOC. Se valora el importante papel que desempeña el proveedor en la compra de libros electrónicos. La BV siempre intenta encontrar un equilibrio entre las necesidades de los usuarios, las posibilidades del mercado y los recursos disponibles. Las compras pueden o no ser consorciadas. Cuando se trata de compra consorciada de libros electrónicos se han de sopesar las ventajas e inconvenientes que esta gestión conlleva, tanto económicas cómo de acceso a los contenidos. Cuando un libro está disponible desde distintas plataformas, hay que estudiar cuál es la que se adecúa mejor a las necesidades de la BV. A la hora de decidir el modelo de compra a utilizar hay que considerar diferentes elementos, como la adquisición individual o en paquetes, la compra directa o subscripción, etc. En segundo lugar, se describen los circuitos internos y tratamientos técnicos que experimentan los libros electrónicos. La gestión de estos procesos la llevan a cabo, en mayor o menor medida, los responsables de los servicios de Adquisición, Catalogación y gestión de la Colección Digital, dependiendo de cómo se haya realizado la adquisición (a perpetuidad o subscripción). Por último, se muestran las distintas opciones de acceso que tiene la BV de la UOC a los libros electrónicos, utilizando para ello un sistema de autenticación de usuarios mediante IP (a través de un porxy WAM). Los puntos de acceso a los libros electrónicos son: el catálogo de la BV, el quick set de libros electrónicos de Metalib, el listado A-Z de SFX, la herramienta de descubrimiento Summon y, además, un nuevo acceso desde el nuevo Web de la BV de la UOC. El acceso a los libros electrónicos de la BV de la UOC es una cuestión que aún no está totalmente resuelta. Desde la nueva Web de la BV se está trabajando para conseguir un punto de acceso único. La principal razón por la que no siempre es posible este único punto de acceso es la existencia o inexistencia de las funcionalidades de metabúsqueda en los libros electrónicos que ofrece cada proveedor. A pesar de la complejidad del nuevo contexto del libro electrónico, la BV de la UOC sigue apostando por los nuevos formatos de lectura, que en el 2013 ha representado el 32,30% del fondo bibliográfico y un 45% sobre el presupuesto dedicado para el 2013. Este proceso se realiza trabajando estrechamente con el profesorado, mediante los contenidos disponibles en la ¿Biblioteca en el aula¿ y potenciando la flexibilidad de los gestores y la construcción de nuevos flujos de trabajo que permitan optimizar y facilitar la transición de la lectura de libros tradicionales a la consulta de monografías en formato electrónico.

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Introduction. The purpose of the present contribution is to perform a detailed anatomic and virtual reality three-dimensional stereoscopic study in order to test the effectiveness of the extended endoscopic endonasal approaches for selected anterior and posterior circulation aneurysms. Methods. The study was divided in two main steps: (1) simulation step, using a dedicated Virtual Reality System (Dextroscope, Volume Interactions); (2) dissection step, in which the feasibility to reach specific vascular territory via the nose was verified in the anatomical laboratory. Results. Good visualization and proximal and distal vascular control of the main midline anterior and posterior circulation territory were achieved during the simulation step as well as in the dissection step (anterior communicating complex, internal carotid, ophthalmic, superior hypophyseal, posterior cerebral and posterior communicating, basilar, superior cerebellar, anterior inferior cerebellar, vertebral, and posterior inferior cerebellar arteries). Conclusion. The present contribution is intended as strictly anatomic study in which we highlighted some specific anterior and posterior circulation aneurysms that can be reached via the nose. For clinical applications of these approaches, some relevant complications, mainly related to the endonasal route, such as proximal and distal vascular control, major arterial bleeding, postoperative cerebrospinal fluid leak, and olfactory disturbances must be considered

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Understanding molecular recognition is one major requirement for drug discovery and design. Physicochemical and shape complementarity between two binding partners is the driving force during complex formation. In this study, the impact of shape within this process is analyzed. Protein binding pockets and co-crystallized ligands are represented by normalized principal moments of inertia ratios (NPRs). The corresponding descriptor space is triangular, with its corners occupied by spherical, discoid, and elongated shapes. An analysis of a selected set of sc-PDB complexes suggests that pockets and bound ligands avoid spherical shapes, which are, however, prevalent in small unoccupied pockets. Furthermore, a direct shape comparison confirms previous studies that on average only one third of a pocket is filled by its bound ligand, supplemented by a 50 % subpocket coverage. In this study, we found that shape complementary is expressed by low pairwise shape distances in NPR space, short distances between the centers-of-mass, and small deviations in the angle between the first principal ellipsoid axes. Furthermore, it is assessed how different binding pocket parameters are related to bioactivity and binding efficiency of the co-crystallized ligand. In addition, the performance of different shape and size parameters of pockets and ligands is evaluated in a virtual screening scenario performed on four representative targets.

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Craving is considered the main variable associated with relapse after smoking cessation. Cue Exposure Therapy (CET) consists of controlled and repeated exposure to drug-related cues with the aim of extinguishing craving responses. Some virtual reality (VR) environments, such as virtual bars or parties, have previously shown their efficacy as tools for eliciting smoking craving. However, in order to adapt this technology to smoking cessation interventions, there is a need for more diverse environments that enhance the probability of generalization of extinction in real life. The main objective of this study was to identify frequent situations that produce smoking craving, as well as detecting specific craving cues in those contexts. Participants were 154 smokers who responded to an ad hoc self-administered inventory for assessing craving level in 12 different situations. Results showed that having a drink in a bar/pub at night, after having lunch/dinner in a restaurant and having a coffee in a cafe or after lunch/dinner at home were reported as the most craving-inducing scenarios. Some differences were found with regard to participants' gender, age, and number of cigarettes smoked per day. Females, younger people, and heavier smokers reported higher levels of craving in most situations. In general, the most widely cited specific cues across the contexts were people smoking, having a coffee, being with friends, and having finished eating. These results are discussed with a view to their consideration in the design of valid and reliable VR environments that could be used in the treatment of nicotine addicts who wish to give up smoking.

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Introducción: Internet permite desarrollar un nuevo modelo de clase teórica basado en la enseñanza no presencial y asincrónica. Objetivo: Publicación virtual de un tema de 'Fundamentos de Cirugía' y evaluación de los resultados de uso y participación de los 80 alumnos matriculados. Material y Métodos: Se diseñaron tres partes: teoría, cuestionario de autoevaluación, y foro de preguntas. La teoría consistía en hipertexto y gráficos, con cuatro tipos de asistentes de aprendizaje: 1) remarcadores de información esencial; 2) información no esencial adicional; 3) mnemotécnicos; 4) ampliación conceptos complejos. El cuestionario consistía en diez preguntas. La pantalla de respuesta ofrecía las respuestas correctas comentadas, la puntuación del alumno, y los centiles de cada nota. El foro de preguntas se basaba en el servidor Ez-Board. El profesor sólo explicó el sistema y los aspectos principales de la lección. Los alumnos podían consultar el material indefinidamente y el foro de preguntas estuvo activo durante dos meses. Resultados: El sistema facilitó la clase por parte del profesor y fue muy bien recibida por los alumnos. Se contabilizaron 239 visitas en dos meses, originadas en la Universidad en 80% de los casos. 16 alumnos usaron el asistente interactivo explicativo. El cuestionario fue respondido por 52 alumnos: 36 alumnos 1 vez y 16 alumnos 2 o más veces. El foro recibió 337 visitas. Se hicieron 38 preguntas de alumnos y 46 respuestas del profesor y otros especialistas. Conclusiones: 1) Diseño y funcionamiento correcto; 2) Excelente acogida y participación; 3) Probable mejora en el aprendizaje y adquisición de conocimientos.

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Background Virtual reality (VR) simulation is increasingly used in surgical disciplines. Since VR simulators measure multiple outcomes, standardized reporting is needed. Methods We present an algorithm for combining multiple VR outcomes into dimension summary measures, which are then integrated into a meaningful total score. We reanalyzed the data of two VR studies applying the algorithm. Results The proposed algorithm was successfully applied to both VR studies. Conclusions The algorithm contributes to standardized and transparent reporting in VR-related research.

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Virtual Laboratories are an indispensablespace for developing practical activities in a Virtual Environment. In the field of Computer and Software Engineering different types of practical activities have tobe performed in order to obtain basic competences which are impossible to achieve by other means. This paper specifies an ontology for a general virtual laboratory.The proposed ontology provides a mechanism to select the best resources needed in a Virtual Laboratory once a specific practical activity has been defined and the maincompetences that students have to achieve in the learning process have been fixed. Furthermore, the proposed ontology can be used to develop an automatic and wizardtool that creates a Moodle Classroom using the practical activity specification and the related competences.

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We report an experiment where participants observed an attack on their virtual body as experienced in an immersive virtual reality (IVR) system. Participants sat by a table with their right hand resting upon it. In IVR, they saw a virtual table that was registered with the real one, and they had a virtual body that substituted their real body seen from a first person perspective. The virtual right hand was collocated with their real right hand. Event-related brain potentials were recorded in two conditions, one where the participant"s virtual hand was attacked with a knife and a control condition where the knife only struck the virtual table. Significantly greater P450 potentials were obtained in the attack condition confirming our expectations that participants had a strong illusion of the virtual hand being their own, which was also strongly supported by questionnaire responses. Higher levels of subjective virtual hand ownership correlated with larger P450 amplitudes. Mu-rhythm event-related desynchronization in the motor cortex and readiness potential (C3-C4) negativity were clearly observed when the virtual hand was threatened as would be expected, if the real hand was threatened and the participant tried to avoid harm. Our results support the idea that event-related potentials may provide a promising non-subjective measure of virtual embodiment. They also support previous experiments on pain observation and are placed into context of similar experiments and studies of body perception and body ownership within cognitive neuroscience.

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We report an experiment where participants observed an attack on their virtual body as experienced in an immersive virtual reality (IVR) system. Participants sat by a table with their right hand resting upon it. In IVR, they saw a virtual table that was registered with the real one, and they had a virtual body that substituted their real body seen from a first person perspective. The virtual right hand was collocated with their real right hand. Event-related brain potentials were recorded in two conditions, one where the participant"s virtual hand was attacked with a knife and a control condition where the knife only struck the virtual table. Significantly greater P450 potentials were obtained in the attack condition confirming our expectations that participants had a strong illusion of the virtual hand being their own, which was also strongly supported by questionnaire responses. Higher levels of subjective virtual hand ownership correlated with larger P450 amplitudes. Mu-rhythm event-related desynchronization in the motor cortex and readiness potential (C3-C4) negativity were clearly observed when the virtual hand was threatened as would be expected, if the real hand was threatened and the participant tried to avoid harm. Our results support the idea that event-related potentials may provide a promising non-subjective measure of virtual embodiment. They also support previous experiments on pain observation and are placed into context of similar experiments and studies of body perception and body ownership within cognitive neuroscience.

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In the rubber hand illusion tactile stimulation seen on a rubber hand, that is synchronous with tactile stimulation felt on the hidden real hand, can lead to an illusion of ownership over the rubber hand. This illusion has been shown to produce a temperature decrease in the hidden hand, suggesting that such illusory ownership produces disownership of the real hand. Here we apply immersive virtual reality (VR) to experimentally investigate this with respect to sensitivity to temperature change. Forty participants experienced immersion in a VR with a virtual body (VB) seen from a first person perspective. For half the participants the VB was consistent in posture and movement with their own body, and in the other half there was inconsistency. Temperature sensitivity on the palm of the hand was measured before and during the virtual experience. The results show that temperature sensitivity decreased in the consistent compared to the inconsistent condition. Moreover, the change in sensitivity was significantly correlated with the subjective illusion of virtual arm ownership but modulated by the illusion of ownership over the full virtual body. This suggests that a full body ownership illusion results in a unification of the virtual and real bodies into one overall entity - with proprioception and tactile sensations on the real body integrated with the visual presence of the virtual body. The results are interpreted in the framework of a"body matrix" recently introduced into the literature.