Improving probabilistic flood forecasting through a data assimilation scheme based on genetic programming

Opportunities offered by high performance computing provide a significant degree of promise in the enhancement of the performance of real-time flood forecasting systems. In this paper, a real-time framework for probabilistic flood forecasting through data assimilation is presented. The distributed rainfall-runoff real-time interactive basin simulator (RIBS) model is selected to simulate the hydrological process in the basin. Although the RIBS model is deterministic, it is run in a probabilistic way through the results of calibration developed in a previous work performed by the authors that identifies the probability distribution functions that best characterise the most relevant model parameters. Adaptive techniques improve the result of flood forecasts because the model can be adapted to observations in real time as new information is available. The new adaptive forecast model based on genetic programming as a data assimilation technique is compared with the previously developed flood forecast model based on the calibration results. Both models are probabilistic as they generate an ensemble of hydrographs, taking the different uncertainties inherent in any forecast process into account. The Manzanares River basin was selected as a case study, with the process being computationally intensive as it requires simulation of many replicas of the ensemble in real time.

Probabilistic reasoning with a bayesian DNA device based on strand displacement

We present a computing model based on the DNA strand displacement technique which performs Bayesian inference. The model will take single stranded DNA as input data, representing the presence or absence of a specific molecular signal (evidence). The program logic encodes the prior probability of a disease and the conditional probability of a signal given the disease playing with a set of different DNA complexes and their ratios. When the input and program molecules interact, they release a different pair of single stranded DNA species whose relative proportion represents the application of Bayes? Law: the conditional probability of the disease given the signal. The models presented in this paper can empower the application of probabilistic reasoning in genetic diagnosis in vitro.

Towards a lightweight mobile semantic-based approach for enhancing interaction with smart objects

This work describes a semantic extension for a user-smart object interaction model based on the ECA paradigm (Event-Condition-Action). In this approach, smart objects publish their sensing (event) and action capabilities in the cloud and mobile devices are prepared to retrieve them and act as mediators to configure personalized behaviours for the objects. In this paper, the information handled by this interaction system has been shaped according several semantic models that, together with the integration of an embedded ontological and rule-based reasoner, are exploited in order to (i) automatically detect incompatible ECA rules configurations and to (ii) support complex ECA rules definitions and execution. This semantic extension may significantly improve the management of smart spaces populated with numerous smart objects from mobile personal devices, as it facilitates the configuration of coherent ECA rules.

Dental Implants Success Prediction: Tomography Based and Data Mining Based Approach.

There are a number of factors that contribute to the success of dental implant operations. Among others, is the choice of location in which the prosthetic tooth is to be implanted. This project offers a new approach to analyse jaw tissue for the purpose of selecting suitable locations for teeth implant operations. The application developed takes as input jaw computed tomography stack of slices and trims data outside the jaw area, which is the point of interest. It then reconstructs a three dimensional model of the jaw highlighting points of interest on the reconstructed model. On another hand, data mining techniques have been utilised in order to construct a prediction model based on an information dataset of previous dental implant operations with observed stability values. The goal is to find patterns within the dataset that would help predicting the success likelihood of an implant.

A decision model for it supplier selection

En los últimos años la externalización de TI ha ganado mucha importancia en el mercado y, por ejemplo, el mercado externalización de servicios de TI sigue creciendo cada año. Ahora más que nunca, las organizaciones son cada vez más los compradores de las capacidades necesarias mediante la obtención de productos y servicios de los proveedores, desarrollando cada vez menos estas capacidades dentro de la empresa. La selección de proveedores de TI es un problema de decisión complejo. Los gerentes que enfrentan una decisión sobre la selección de proveedores de TI tienen dificultades en la elaboración de lo que hay que pensar, además en sus discursos. También de acuerdo con un estudio del SEI (Software Engineering Institute) [40], del 20 al 25 por ciento de los grandes proyectos de adquisición de TI fracasan en dos años y el 50 por ciento fracasan dentro de cinco años. La mala gestión, la mala definición de requisitos, la falta de evaluaciones exhaustivas, que pueden ser utilizadas para llegar a los mejores candidatos para la contratación externa, la selección de proveedores y los procesos de contratación inadecuados, la insuficiencia de procedimientos de selección tecnológicos, y los cambios de requisitos no controlados son factores que contribuyen al fracaso del proyecto. La mayoría de los fracasos podrían evitarse si el cliente aprendiese a comprender los problemas de decisión, hacer un mejor análisis de decisiones, y el buen juicio. El objetivo principal de este trabajo es el desarrollo de un modelo de decisión para la selección de proveedores de TI que tratará de reducir la cantidad de fracasos observados en las relaciones entre el cliente y el proveedor. La mayor parte de estos fracasos son causados por una mala selección, por parte del cliente, del proveedor. Además de estos problemas mostrados anteriormente, la motivación para crear este trabajo es la inexistencia de cualquier modelo de decisión basado en un multi modelo (mezcla de modelos adquisición y métodos de decisión) para el problema de la selección de proveedores de TI. En el caso de estudio, nueve empresas españolas fueron analizadas de acuerdo con el modelo de decisión para la selección de proveedores de TI desarrollado en este trabajo. Dos softwares se utilizaron en este estudio de caso: Expert Choice, y D-Sight. ABSTRACT In the past few years IT outsourcing has gained a lot of importance in the market and, for example, the IT services outsourcing market is still growing every year. Now more than ever, organizations are increasingly becoming acquirers of needed capabilities by obtaining products and services from suppliers and developing less and less of these capabilities in-house. IT supplier selection is a complex and opaque decision problem. Managers facing a decision about IT supplier selection have difficulty in framing what needs to be thought about further in their discourses. Also according to a study from SEI (Software Engineering Institute) [40], 20 to 25 percent of large information technology (IT) acquisition projects fail within two years and 50 percent fail within five years. Mismanagement, poor requirements definition, lack of comprehensive evaluations, which can be used to come up with the best candidates for outsourcing, inadequate supplier selection and contracting processes, insufficient technology selection procedures, and uncontrolled requirements changes are factors that contribute to project failure. The majority of project failures could be avoided if the acquirer learns how to understand the decision problems, make better decision analysis, and good judgment. The main objective of this work is the development of a decision model for IT supplier selection that will try to decrease the amount of failures seen in the relationships between the client-supplier. Most of these failures are caused by a not well selection of the supplier. Besides these problems showed above, the motivation to create this work is the inexistence of any decision model based on multi model (mixture of acquisition models and decision methods) for the problem of IT supplier selection. In the case study, nine different Spanish companies were analyzed based on the IT supplier selection decision model developed in this work. Two software products were used in this case study, Expert Choice and D-Sight.

Novel fast random search clustering approach for mixing matrix identification in MIMO linear blind inverse problems with sparse inputs

In this paper we propose a novel fast random search clustering (RSC) algorithm for mixing matrix identification in multiple input multiple output (MIMO) linear blind inverse problems with sparse inputs. The proposed approach is based on the clustering of the observations around the directions given by the columns of the mixing matrix that occurs typically for sparse inputs. Exploiting this fact, the RSC algorithm proceeds by parameterizing the mixing matrix using hyperspherical coordinates, randomly selecting candidate basis vectors (i.e. clustering directions) from the observations, and accepting or rejecting them according to a binary hypothesis test based on the Neyman–Pearson criterion. The RSC algorithm is not tailored to any specific distribution for the sources, can deal with an arbitrary number of inputs and outputs (thus solving the difficult under-determined problem), and is applicable to both instantaneous and convolutive mixtures. Extensive simulations for synthetic and real data with different number of inputs and outputs, data size, sparsity factors of the inputs and signal to noise ratios confirm the good performance of the proposed approach under moderate/high signal to noise ratios. RESUMEN. Método de separación ciega de fuentes para señales dispersas basado en la identificación de la matriz de mezcla mediante técnicas de "clustering" aleatorio.

Automatic segmentation of abdominal aortic aneurysm from medical images based on active shape models and texture models

A semi-automatic segmentation algorithm for abdominal aortic aneurysms (AAA), and based on Active Shape Models (ASM) and texture models, is presented in this work. The texture information is provided by a set of four 3D magnetic resonance (MR) images, composed of axial slices of the abdomen, where lumen, wall and intraluminal thrombus (ILT) are visible. Due to the reduced number of images in the MRI training set, an ASM and a custom texture model based on border intensity statistics are constructed. For the same reason the shape is characterized from 35-computed tomography angiography (CTA) images set so the shape variations are better represented. For the evaluation, leave-one-out experiments have been held over the four MRI set.

A model to develop a platform for personalised health applications

Antecedentes Europa vive una situación insostenible. Desde el 2008 se han reducido los recursos de los gobiernos a raíz de la crisis económica. El continente Europeo envejece con ritmo constante al punto que se prevé que en 2050 habrá sólo dos trabajadores por jubilado [54]. A esta situación se le añade el aumento de la incidencia de las enfermedades crónicas, relacionadas con el envejecimiento, cuyo coste puede alcanzar el 7% del PIB de un país [51]. Es necesario un cambio de paradigma. Una nueva manera de cuidar de la salud de las personas: sustentable, eficaz y preventiva más que curativa. Algunos estudios abogan por el cuidado personalizado de la salud (pHealth). En este modelo las prácticas médicas son adaptadas e individualizadas al paciente, desde la detección de los factores de riesgo hasta la personalización de los tratamientos basada en la respuesta del individuo [81]. El cuidado personalizado de la salud está asociado a menudo al uso de las tecnologías de la información y comunicación (TICs) que, con su desarrollo exponencial, ofrecen oportunidades interesantes para la mejora de la salud. El cambio de paradigma hacia el pHealth está lentamente ocurriendo, tanto en el ámbito de la investigación como en la industria, pero todavía no de manera significativa. Existen todavía muchas barreras relacionadas a la economía, a la política y la cultura. También existen barreras puramente tecnológicas, como la falta de sistemas de información interoperables [199]. A pesar de que los aspectos de interoperabilidad están evolucionando, todavía hace falta un diseño de referencia especialmente direccionado a la implementación y el despliegue en gran escala de sistemas basados en pHealth. La presente Tesis representa un intento de organizar la disciplina de la aplicación de las TICs al cuidado personalizado de la salud en un modelo de referencia, que permita la creación de plataformas de desarrollo de software para simplificar tareas comunes de desarrollo en este dominio. Preguntas de investigación RQ1 >Es posible definir un modelo, basado en técnicas de ingeniería del software, que represente el dominio del cuidado personalizado de la salud de una forma abstracta y representativa? RQ2 >Es posible construir una plataforma de desarrollo basada en este modelo? RQ3 >Esta plataforma ayuda a los desarrolladores a crear sistemas pHealth complejos e integrados? Métodos Para la descripción del modelo se adoptó el estándar ISO/IEC/IEEE 42010por ser lo suficientemente general y abstracto para el amplio enfoque de esta tesis [25]. El modelo está definido en varias partes: un modelo conceptual, expresado a través de mapas conceptuales que representan las partes interesadas (stakeholders), los artefactos y la información compartida; y escenarios y casos de uso para la descripción de sus funcionalidades. El modelo fue desarrollado de acuerdo a la información obtenida del análisis de la literatura, incluyendo 7 informes industriales y científicos, 9 estándares, 10 artículos en conferencias, 37 artículos en revistas, 25 páginas web y 5 libros. Basándose en el modelo se definieron los requisitos para la creación de la plataforma de desarrollo, enriquecidos por otros requisitos recolectados a través de una encuesta realizada a 11 ingenieros con experiencia en la rama. Para el desarrollo de la plataforma, se adoptó la metodología de integración continua [74] que permitió ejecutar tests automáticos en un servidor y también desplegar aplicaciones en una página web. En cuanto a la metodología utilizada para la validación se adoptó un marco para la formulación de teorías en la ingeniería del software [181]. Esto requiere el desarrollo de modelos y proposiciones que han de ser validados dentro de un ámbito de investigación definido, y que sirvan para guiar al investigador en la búsqueda de la evidencia necesaria para justificarla. La validación del modelo fue desarrollada mediante una encuesta online en tres rondas con un número creciente de invitados. El cuestionario fue enviado a 134 contactos y distribuido en algunos canales públicos como listas de correo y redes sociales. El objetivo era evaluar la legibilidad del modelo, su nivel de cobertura del dominio y su potencial utilidad en el diseño de sistemas derivados. El cuestionario incluía preguntas cuantitativas de tipo Likert y campos para recolección de comentarios. La plataforma de desarrollo fue validada en dos etapas. En la primera etapa se utilizó la plataforma en un experimento a pequeña escala, que consistió en una sesión de entrenamiento de 12 horas en la que 4 desarrolladores tuvieron que desarrollar algunos casos de uso y reunirse en un grupo focal para discutir su uso. La segunda etapa se realizó durante los tests de un proyecto en gran escala llamado HeartCycle [160]. En este proyecto un equipo de diseñadores y programadores desarrollaron tres aplicaciones en el campo de las enfermedades cardio-vasculares. Una de estas aplicaciones fue testeada en un ensayo clínico con pacientes reales. Al analizar el proyecto, el equipo de desarrollo se reunió en un grupo focal para identificar las ventajas y desventajas de la plataforma y su utilidad. Resultados Por lo que concierne el modelo que describe el dominio del pHealth, la parte conceptual incluye una descripción de los roles principales y las preocupaciones de los participantes, un modelo de los artefactos TIC que se usan comúnmente y un modelo para representar los datos típicos que son necesarios formalizar e intercambiar entre sistemas basados en pHealth. El modelo funcional incluye un conjunto de 18 escenarios, repartidos en: punto de vista de la persona asistida, punto de vista del cuidador, punto de vista del desarrollador, punto de vista de los proveedores de tecnologías y punto de vista de las autoridades; y un conjunto de 52 casos de uso repartidos en 6 categorías: actividades de la persona asistida, reacciones del sistema, actividades del cuidador, \engagement" del usuario, actividades del desarrollador y actividades de despliegue. Como resultado del cuestionario de validación del modelo, un total de 65 personas revisó el modelo proporcionando su nivel de acuerdo con las dimensiones evaluadas y un total de 248 comentarios sobre cómo mejorar el modelo. Los conocimientos de los participantes variaban desde la ingeniería del software (70%) hasta las especialidades médicas (15%), con declarado interés en eHealth (24%), mHealth (16%), Ambient Assisted Living (21%), medicina personalizada (5%), sistemas basados en pHealth (15%), informática médica (10%) e ingeniería biomédica (8%) con una media de 7.25_4.99 años de experiencia en estas áreas. Los resultados de la encuesta muestran que los expertos contactados consideran el modelo fácil de leer (media de 1.89_0.79 siendo 1 el valor más favorable y 5 el peor), suficientemente abstracto (1.99_0.88) y formal (2.13_0.77), con una cobertura suficiente del dominio (2.26_0.95), útil para describir el dominio (2.02_0.7) y para generar sistemas más específicos (2_0.75). Los expertos también reportan un interés parcial en utilizar el modelo en su trabajo (2.48_0.91). Gracias a sus comentarios, el modelo fue mejorado y enriquecido con conceptos que faltaban, aunque no se pudo demonstrar su mejora en las dimensiones evaluadas, dada la composición diferente de personas en las tres rondas de evaluación. Desde el modelo, se generó una plataforma de desarrollo llamada \pHealth Patient Platform (pHPP)". La plataforma desarrollada incluye librerías, herramientas de programación y desarrollo, un tutorial y una aplicación de ejemplo. Se definieron cuatro módulos principales de la arquitectura: el Data Collection Engine, que permite abstraer las fuentes de datos como sensores o servicios externos, mapeando los datos a bases de datos u ontologías, y permitiendo interacción basada en eventos; el GUI Engine, que abstrae la interfaz de usuario en un modelo de interacción basado en mensajes; y el Rule Engine, que proporciona a los desarrolladores un medio simple para programar la lógica de la aplicación en forma de reglas \if-then". Después de que la plataforma pHPP fue utilizada durante 5 años en el proyecto HeartCycle, 5 desarrolladores fueron reunidos en un grupo de discusión para analizar y evaluar la plataforma. De estas evaluaciones se concluye que la plataforma fue diseñada para encajar las necesidades de los ingenieros que trabajan en la rama, permitiendo la separación de problemas entre las distintas especialidades, y simplificando algunas tareas de desarrollo como el manejo de datos y la interacción asíncrona. A pesar de ello, se encontraron algunos defectos a causa de la inmadurez de algunas tecnologías empleadas, y la ausencia de algunas herramientas específicas para el dominio como el procesado de datos o algunos protocolos de comunicación relacionados con la salud. Dentro del proyecto HeartCycle la plataforma fue utilizada para el desarrollo de la aplicación \Guided Exercise", un sistema TIC para la rehabilitación de pacientes que han sufrido un infarto del miocardio. El sistema fue testeado en un ensayo clínico randomizado en el cual a 55 pacientes se les dio el sistema para su uso por 21 semanas. De los resultados técnicos del ensayo se puede concluir que, a pesar de algunos errores menores prontamente corregidos durante el estudio, la plataforma es estable y fiable. Conclusiones La investigación llevada a cabo en esta Tesis y los resultados obtenidos proporcionan las respuestas a las tres preguntas de investigación que motivaron este trabajo: RQ1 Se ha desarrollado un modelo para representar el dominio de los sistemas personalizados de salud. La evaluación hecha por los expertos de la rama concluye que el modelo representa el dominio con precisión y con un balance apropiado entre abstracción y detalle. RQ2 Se ha desarrollado, con éxito, una plataforma de desarrollo basada en el modelo. RQ3 Se ha demostrado que la plataforma es capaz de ayudar a los desarrolladores en la creación de software pHealth complejos. Las ventajas de la plataforma han sido demostradas en el ámbito de un proyecto de gran escala, aunque el enfoque genérico adoptado indica que la plataforma podría ofrecer beneficios también en otros contextos. Los resultados de estas evaluaciones ofrecen indicios de que, ambos, el modelo y la plataforma serán buenos candidatos para poderse convertir en una referencia para futuros desarrollos de sistemas pHealth. ABSTRACT Background Europe is living in an unsustainable situation. The economic crisis has been reducing governments' economic resources since 2008 and threatening social and health systems, while the proportion of older people in the European population continues to increase so that it is foreseen that in 2050 there will be only two workers per retiree [54]. To this situation it should be added the rise, strongly related to age, of chronic diseases the burden of which has been estimated to be up to the 7% of a country's gross domestic product [51]. There is a need for a paradigm shift, the need for a new way of caring for people's health, shifting the focus from curing conditions that have arisen to a sustainable and effective approach with the emphasis on prevention. Some advocate the adoption of personalised health care (pHealth), a model where medical practices are tailored to the patient's unique life, from the detection of risk factors to the customization of treatments based on each individual's response [81]. Personalised health is often associated to the use of Information and Communications Technology (ICT), that, with its exponential development, offers interesting opportunities for improving healthcare. The shift towards pHealth is slowly taking place, both in research and in industry, but the change is not significant yet. Many barriers still exist related to economy, politics and culture, while others are purely technological, like the lack of interoperable information systems [199]. Though interoperability aspects are evolving, there is still the need of a reference design, especially tackling implementation and large scale deployment of pHealth systems. This thesis contributes to organizing the subject of ICT systems for personalised health into a reference model that allows for the creation of software development platforms to ease common development issues in the domain. Research questions RQ1 Is it possible to define a model, based on software engineering techniques, for representing the personalised health domain in an abstract and representative way? RQ2 Is it possible to build a development platform based on this model? RQ3 Does the development platform help developers create complex integrated pHealth systems? Methods As method for describing the model, the ISO/IEC/IEEE 42010 framework [25] is adopted for its generality and high level of abstraction. The model is specified in different parts: a conceptual model, which makes use of concept maps, for representing stakeholders, artefacts and shared information, and in scenarios and use cases for the representation of the functionalities of pHealth systems. The model was derived from literature analysis, including 7 industrial and scientific reports, 9 electronic standards, 10 conference proceedings papers, 37 journal papers, 25 websites and 5 books. Based on the reference model, requirements were drawn for building the development platform enriched with a set of requirements gathered in a survey run among 11 experienced engineers. For developing the platform, the continuous integration methodology [74] was adopted which allowed to perform automatic tests on a server and also to deploy packaged releases on a web site. As a validation methodology, a theory building framework for SW engineering was adopted from [181]. The framework, chosen as a guide to find evidence for justifying the research questions, imposed the creation of theories based on models and propositions to be validated within a scope. The validation of the model was conducted as an on-line survey in three validation rounds, encompassing a growing number of participants. The survey was submitted to 134 experts of the field and on some public channels like relevant mailing lists and social networks. Its objective was to assess the model's readability, its level of coverage of the domain and its potential usefulness in the design of actual, derived systems. The questionnaires included quantitative Likert scale questions and free text inputs for comments. The development platform was validated in two scopes. As a small-scale experiment, the platform was used in a 12 hours training session where 4 developers had to perform an exercise consisting in developing a set of typical pHealth use cases At the end of the session, a focus group was held to identify benefits and drawbacks of the platform. The second validation was held as a test-case study in a large scale research project called HeartCycle the aim of which was to develop a closed-loop disease management system for heart failure and coronary heart disease patients [160]. During this project three applications were developed by a team of programmers and designers. One of these applications was tested in a clinical trial with actual patients. At the end of the project, the team was interviewed in a focus group to assess the role the platform had within the project. Results For what regards the model that describes the pHealth domain, its conceptual part includes a description of the main roles and concerns of pHealth stakeholders, a model of the ICT artefacts that are commonly adopted and a model representing the typical data that need to be formalized among pHealth systems. The functional model includes a set of 18 scenarios, divided into assisted person's view, caregiver's view, developer's view, technology and services providers' view and authority's view, and a set of 52 Use Cases grouped in 6 categories: assisted person's activities, system reactions, caregiver's activities, user engagement, developer's activities and deployer's activities. For what concerns the validation of the model, a total of 65 people participated in the online survey providing their level of agreement in all the assessed dimensions and a total of 248 comments on how to improve and complete the model. Participants' background spanned from engineering and software development (70%) to medical specialities (15%), with declared interest in the fields of eHealth (24%), mHealth (16%), Ambient Assisted Living (21%), Personalized Medicine (5%), Personal Health Systems (15%), Medical Informatics (10%) and Biomedical Engineering (8%) with an average of 7.25_4.99 years of experience in these fields. From the analysis of the answers it is possible to observe that the contacted experts considered the model easily readable (average of 1.89_0.79 being 1 the most favourable scoring and 5 the worst), sufficiently abstract (1.99_0.88) and formal (2.13_0.77) for its purpose, with a sufficient coverage of the domain (2.26_0.95), useful for describing the domain (2.02_0.7) and for generating more specific systems (2_0.75) and they reported a partial interest in using the model in their job (2.48_0.91). Thanks to their comments, the model was improved and enriched with concepts that were missing at the beginning, nonetheless it was not possible to prove an improvement among the iterations, due to the diversity of the participants in the three rounds. From the model, a development platform for the pHealth domain was generated called pHealth Patient Platform (pHPP). The platform includes a set of libraries, programming and deployment tools, a tutorial and a sample application. The main four modules of the architecture are: the Data Collection Engine, which allows abstracting sources of information like sensors or external services, mapping data to databases and ontologies, and allowing event-based interaction and filtering, the GUI Engine, which abstracts the user interface in a message-like interaction model, the Workow Engine, which allows programming the application's user interaction ows with graphical workows, and the Rule Engine, which gives developers a simple means for programming the application's logic in the form of \if-then" rules. After the 5 years experience of HeartCycle, partially programmed with pHPP, 5 developers were joined in a focus group to discuss the advantages and drawbacks of the platform. The view that emerged from the training course and the focus group was that the platform is well-suited to the needs of the engineers working in the field, it allowed the separation of concerns among the different specialities and it simplified some common development tasks like data management and asynchronous interaction. Nevertheless, some deficiencies were pointed out in terms of a lack of maturity of some technological choices, and for the absence of some domain-specific tools, e.g. for data processing or for health-related communication protocols. Within HeartCycle, the platform was used to develop part of the Guided Exercise system, a composition of ICT tools for the physical rehabilitation of patients who suffered from myocardial infarction. The system developed using the platform was tested in a randomized controlled clinical trial, in which 55 patients used the system for 21 weeks. The technical results of this trial showed that the system was stable and reliable. Some minor bugs were detected, but these were promptly corrected using the platform. This shows that the platform, as well as facilitating the development task, can be successfully used to produce reliable software. Conclusions The research work carried out in developing this thesis provides responses to the three three research questions that were the motivation for the work. RQ1 A model was developed representing the domain of personalised health systems, and the assessment of experts in the field was that it represents the domain accurately, with an appropriate balance between abstraction and detail. RQ2 A development platform based on the model was successfully developed. RQ3 The platform has been shown to assist developers create complex pHealth software. This was demonstrated within the scope of one large-scale project, but the generic approach adopted provides indications that it would offer benefits more widely. The results of these evaluations provide indications that both the model and the platform are good candidates for being a reference for future pHealth developments.

Business model with discount incentive in a P2P-cloud multimedia streaming system

Today P2P faces two important challenges: design of mechanisms to encourage users' collaboration in multimedia live streaming services; design of reliable algorithms with QoS provision, to encourage the multimedia providers employ the P2P topology in commercial live streaming systems. We believe that these two challenges are tightly-related and there is much to be done with respect. This paper analyzes the effect of user behavior in a multi-tree P2P overlay and describes a business model based on monetary discount as incentive in a P2P-Cloud multimedia streaming system. We believe a discount model can boost up users' cooperation and loyalty and enhance the overall system integrity and performance. Moreover the model bounds the constraints for a provider's revenue and cost if the P2P system is leveraged on a cloud infrastructure. Our case study shows that a streaming system provider can establish or adapt his business model by applying the described bounds to achieve a good discount-revenue trade-off and promote the system to the users.

Structure Variation And Dynamics of the Nuclear Ribosomal Intergenic Spacer Region in Key Gibberella Fujikuroi Complex Species

The intergenic spacer (IGS) region of the ribosomal DNA was cloned and sequenced in eight species within the Gibberella fujikuroi species complex with anamorphs in the genus Fusarium , a group that includes the most relevant toxigenic species. DNA sequence analyses revealed two categories of repeated elements: long repeats and short repeats of 125 and 8 bp, respectively. Long repeats were present in two copies and were conserved in all the species analyzed, whereas different numbers of short repeat elements were observed, leading to species-specific IGS sequences with different length. In Fusarium subglutinans and Fusarium nygamai , these differences seemed to be the result of duplication and deletion events. Here, we propose a model based on unequal crossing over that can explain these processes. The partial IGS sequence of 22 Fusarium proliferatum isolates was also obtained to study variation at the intraspecific level. The results revealed no differences in terms of number or pattern of repeated elements and detected frequent gene conversion events. These results suggest that the homogenization observed at the intraspecific level might not be achieved primarily by unequal crossing-over events but rather by processes associated with recombination such as gene conversion events.

Secure optical networks based on quantum key distribution and weakly trusted repeaters

Abstract—In this paper we explore how recent technologies can improve the security of optical networks. In particular, we study how to use quantum key distribution(QKD) in common optical network infrastructures and propose a method to overcome its distance limitations. QKD is the first technology offering information theoretic secretkey distribution that relies only on the fundamental principles of quantum physics. Point-to-point QKDdevices have reached a mature industrial state; however, these devices are severely limited in distance, since signals at the quantum level (e.g., single photons) are highly affected by the losses in the communication channel and intermediate devices. To overcome this limitation, intermediate nodes (i.e., repeaters) are used. Both quantum-regime and trusted, classical repeaters have been proposed in the QKD literature, but only the latter can be implemented in practice. As a novelty, we propose here a new QKD network model based on the use of not fully trusted intermediate nodes, referred to as weakly trusted repeaters. This approach forces the attacker to simultaneously break several paths to get access to the exchanged key, thus improving significantly the security of the network. We formalize the model using network codes and provide real scenarios that allow users to exchange secure keys over metropolitan optical networks using only passive components. Moreover, the theoretical framework allows one to extend these scenarios not only to accommodate more complex trust constraints, but also to consider robustness and resiliency constraints on the network.

Supporting decision making under uncertainty: Development of a participatory integrated model for water management in the middle Guadiana river basin.

Following the Integrated Water Resources Management approach, the European Water Framework Directive demands Member States to develop water management plans at the catchment level. Those plans have to integrate the different interests and must be developed with stakeholder participation. To face these requirements, managers need tools to assess the impacts of possible management alternatives on natural and socio-economic systems. These tools should ideally be able to address the complexity and uncertainties of the water system, while serving as a platform for stakeholder participation. The objective of our research was to develop a participatory integrated assessment model, based on the combination of a crop model, an economic model and a participatory Bayesian network, with an application in the middle Guadiana sub-basin, in Spain. The methodology is intended to capture the complexity of water management problems, incorporating the relevant sectors, as well as the relevant scales involved in water management decision making. The integrated model has allowed us testing different management, market and climate change scenarios and assessing the impacts of such scenarios on the natural system (crops), on the socio-economic system (farms) and on the environment (water resources). Finally, this integrated assessment modelling process has allowed stakeholder participation, complying with the main requirements of current European water laws.

Análisis de los factores de adopción de comercio electrónico en segmentos de consumidores finales. Aplicación al caso español

El comercio electrónico ha experimentado un fuerte crecimiento en los últimos años, favorecido especialmente por el aumento de las tasas de penetración de Internet en todo el mundo. Sin embargo, no todos los países están evolucionando de la misma manera, con un espectro que va desde las naciones pioneras en desarrollo de tecnologías de la información y comunicaciones, que cuentan con una elevado porcentaje de internautas y de compradores online, hasta las rezagadas de rápida adopción en las que, pese a contar con una menor penetración de acceso, presentan una alta tasa de internautas compradores. Entre ambos extremos se encuentran países como España que, aunque alcanzó hace años una tasa considerable de penetración de usuarios de Internet, no ha conseguido una buena tasa de transformación de internautas en compradores. Pese a que el comercio electrónico ha experimentado importantes aumentos en los últimos años, sus tasas de crecimiento siguen estando por debajo de países con características socio-económicas similares. Para intentar conocer las razones que afectan a la adopción del comercio por parte de los compradores, la investigación científica del fenómeno ha empleado diferentes enfoques teóricos. De entre todos ellos ha destacado el uso de los modelos de adopción, proveniente de la literatura de adopción de sistemas de información en entornos organizativos. Estos modelos se basan en las percepciones de los compradores para determinar qué factores pueden predecir mejor la intención de compra y, en consecuencia, la conducta real de compra de los usuarios. Pese a que en los últimos años han proliferado los trabajos de investigación que aplican los modelos de adopción al comercio electrónico, casi todos tratan de validar sus hipótesis mediante el análisis de muestras de consumidores tratadas como un único conjunto, y del que se obtienen conclusiones generales. Sin embargo, desde el origen del marketing, y en especial a partir de la segunda mitad del siglo XIX, se considera que existen diferencias en el comportamiento de los consumidores, que pueden ser debidas a características demográficas, sociológicas o psicológicas. Estas diferencias se traducen en necesidades distintas, que sólo podrán ser satisfechas con una oferta adaptada por parte de los vendedores. Además, por contar el comercio electrónico con unas características particulares que lo diferencian del comercio tradicional –especialmente por la falta de contacto físico entre el comprador y el producto– a las diferencias en la adopción para cada consumidor se le añaden las diferencias derivadas del tipo de producto adquirido, que si bien habían sido consideradas en el canal físico, en el comercio electrónico cobran especial relevancia. A la vista de todo ello, el presente trabajo pretende abordar el estudio de los factores determinantes de la intención de compra y la conducta real de compra en comercio electrónico por parte del consumidor final español, teniendo en cuenta el tipo de segmento al que pertenezca dicho comprador y el tipo de producto considerado. Para ello, el trabajo contiene ocho apartados entre los que se encuentran cuatro bloques teóricos y tres bloques empíricos, además de las conclusiones. Estos bloques dan lugar a los siguientes ocho capítulos por orden de aparición en el trabajo: introducción, situación del comercio electrónico, modelos de adopción de tecnología, segmentación en comercio electrónico, diseño previo del trabajo empírico, diseño de la investigación, análisis de los resultados y conclusiones. El capítulo introductorio justifica la relevancia de la investigación, además de fijar los objetivos, la metodología y las fases seguidas para el desarrollo del trabajo. La justificación se complementa con el segundo capítulo, que cuenta con dos elementos principales: en primer lugar se define el concepto de comercio electrónico y se hace una breve retrospectiva desde sus orígenes hasta la situación actual en un contexto global; en segundo lugar, el análisis estudia la evolución del comercio electrónico en España, mostrando su desarrollo y situación presente a partir de sus principales indicadores. Este apartado no sólo permite conocer el contexto de la investigación, sino que además permite contrastar la relevancia de la muestra utilizada en el presente estudio con el perfil español respecto al comercio electrónico. Los capítulos tercero –modelos de adopción de tecnologías– y cuarto –segmentación en comercio electrónico– sientan las bases teóricas necesarias para abordar el estudio. En el capítulo tres se hace una revisión general de la literatura de modelos de adopción de tecnología y, en particular, de los modelos de adopción empleados en el ámbito del comercio electrónico. El resultado de dicha revisión deriva en la construcción de un modelo adaptado basado en los modelos UTAUT (Unified Theory of Acceptance and Use of Technology, Teoría unificada de la aceptación y el uso de la tecnología) y UTAUT2, combinado con dos factores específicos de adopción del comercio electrónico: el riesgo percibido y la confianza percibida. Por su parte, en el capítulo cuatro se revisan las metodologías de segmentación de clientes y productos empleadas en la literatura. De dicha revisión se obtienen un amplio conjunto de variables de las que finalmente se escogen nueve variables de clasificación que se consideran adecuadas tanto por su adaptación al contexto del comercio electrónico como por su adecuación a las características de la muestra empleada para validar el modelo. Las nueve variables se agrupan en tres conjuntos: variables de tipo socio-demográfico –género, edad, nivel de estudios, nivel de ingresos, tamaño de la unidad familiar y estado civil–, de comportamiento de compra – experiencia de compra por Internet y frecuencia de compra por Internet– y de tipo psicográfico –motivaciones de compra por Internet. La segunda parte del capítulo cuatro se dedica a la revisión de los criterios empleados en la literatura para la clasificación de los productos en el contexto del comercio electrónico. De dicha revisión se obtienen quince grupos de variables que pueden tomar un total de treinta y cuatro valores, lo que deriva en un elevado número de combinaciones posibles. Sin embargo, pese a haber sido utilizados en el contexto del comercio electrónico, no en todos los casos se ha comprobado la influencia de dichas variables respecto a la intención de compra o la conducta real de compra por Internet; por este motivo, y con el objetivo de definir una clasificación robusta y abordable de tipos de productos, en el capitulo cinco se lleva a cabo una validación de las variables de clasificación de productos mediante un experimento previo con 207 muestras. Seleccionando sólo aquellas variables objetivas que no dependan de la interpretación personal del consumidores y que determinen grupos significativamente distintos respecto a la intención y conducta de compra de los consumidores, se obtiene un modelo de dos variables que combinadas dan lugar a cuatro tipos de productos: bien digital, bien no digital, servicio digital y servicio no digital. Definidos el modelo de adopción y los criterios de segmentación de consumidores y productos, en el sexto capítulo se desarrolla el modelo completo de investigación formado por un conjunto de hipótesis obtenidas de la revisión de la literatura de los capítulos anteriores, en las que se definen las hipótesis de investigación con respecto a las influencias esperadas de las variables de segmentación sobre las relaciones del modelo de adopción. Este modelo confiere a la investigación un carácter social y de tipo fundamentalmente exploratorio, en el que en muchos casos ni siquiera se han encontrado evidencias empíricas previas que permitan el enunciado de hipótesis sobre la influencia de determinadas variables de segmentación. El capítulo seis contiene además la descripción del instrumento de medida empleado en la investigación, conformado por un total de 125 preguntas y sus correspondientes escalas de medida, así como la descripción de la muestra representativa empleada en la validación del modelo, compuesta por un grupo de 817 personas españolas o residentes en España. El capítulo siete constituye el núcleo del análisis empírico del trabajo de investigación, que se compone de dos elementos fundamentales. Primeramente se describen las técnicas estadísticas aplicadas para el estudio de los datos que, dada la complejidad del análisis, se dividen en tres grupos fundamentales: Método de mínimos cuadrados parciales (PLS, Partial Least Squares): herramienta estadística de análisis multivariante con capacidad de análisis predictivo que se emplea en la determinación de las relaciones estructurales de los modelos propuestos. Análisis multigrupo: conjunto de técnicas que permiten comparar los resultados obtenidos con el método PLS entre dos o más grupos derivados del uso de una o más variables de segmentación. En este caso se emplean cinco métodos de comparación, lo que permite asimismo comparar los rendimientos de cada uno de los métodos. Determinación de segmentos no identificados a priori: en el caso de algunas de las variables de segmentación no existe un criterio de clasificación definido a priori, sino que se obtiene a partir de la aplicación de técnicas estadísticas de clasificación. En este caso se emplean dos técnicas fundamentales: análisis de componentes principales –dado el elevado número de variables empleadas para la clasificación– y análisis clúster –del que se combina una técnica jerárquica que calcula el número óptimo de segmentos, con una técnica por etapas que es más eficiente en la clasificación, pero exige conocer el número de clústeres a priori. La aplicación de dichas técnicas estadísticas sobre los modelos resultantes de considerar los distintos criterios de segmentación, tanto de clientes como de productos, da lugar al análisis de un total de 128 modelos de adopción de comercio electrónico y 65 comparaciones multigrupo, cuyos resultados y principales consideraciones son elaboradas a lo largo del capítulo. Para concluir, el capítulo ocho recoge las conclusiones del trabajo divididas en cuatro partes diferenciadas. En primer lugar se examina el grado de alcance de los objetivos planteados al inicio de la investigación; después se desarrollan las principales contribuciones que este trabajo aporta tanto desde el punto de vista metodológico, como desde los punto de vista teórico y práctico; en tercer lugar, se profundiza en las conclusiones derivadas del estudio empírico, que se clasifican según los criterios de segmentación empleados, y que combinan resultados confirmatorios y exploratorios; por último, el trabajo recopila las principales limitaciones de la investigación, tanto de carácter teórico como empírico, así como aquellos aspectos que no habiendo podido plantearse dentro del contexto de este estudio, o como consecuencia de los resultados alcanzados, se presentan como líneas futuras de investigación. ABSTRACT Favoured by an increase of Internet penetration rates across the globe, electronic commerce has experienced a rapid growth over the last few years. Nevertheless, adoption of electronic commerce has differed from one country to another. On one hand, it has been observed that countries leading e-commerce adoption have a large percentage of Internet users as well as of online purchasers; on the other hand, other markets, despite having a low percentage of Internet users, show a high percentage of online buyers. Halfway between those two ends of the spectrum, we find countries such as Spain which, despite having moderately high Internet penetration rates and similar socio-economic characteristics as some of the leading countries, have failed to turn Internet users into active online buyers. Several theoretical approaches have been taken in an attempt to define the factors that influence the use of electronic commerce systems by customers. One of the betterknown frameworks to characterize adoption factors is the acceptance modelling theory, which is derived from the information systems adoption in organizational environments. These models are based on individual perceptions on which factors determine purchase intention, as a mean to explain users’ actual purchasing behaviour. Even though research on electronic commerce adoption models has increased in terms of volume and scope over the last years, the majority of studies validate their hypothesis by using a single sample of consumers from which they obtain general conclusions. Nevertheless, since the birth of marketing, and more specifically from the second half of the 19th century, differences in consumer behaviour owing to demographic, sociologic and psychological characteristics have also been taken into account. And such differences are generally translated into different needs that can only be satisfied when sellers adapt their offer to their target market. Electronic commerce has a number of features that makes it different when compared to traditional commerce; the best example of this is the lack of physical contact between customers and products, and between customers and vendors. Other than that, some differences that depend on the type of product may also play an important role in electronic commerce. From all the above, the present research aims to address the study of the main factors influencing purchase intention and actual purchase behaviour in electronic commerce by Spanish end-consumers, taking into consideration both the customer group to which they belong and the type of product being purchased. In order to achieve this goal, this Thesis is structured in eight chapters: four theoretical sections, three empirical blocks and a final section summarizing the conclusions derived from the research. The chapters are arranged in sequence as follows: introduction, current state of electronic commerce, technology adoption models, electronic commerce segmentation, preliminary design of the empirical work, research design, data analysis and results, and conclusions. The introductory chapter offers a detailed justification of the relevance of this study in the context of e-commerce adoption research; it also sets out the objectives, methodology and research stages. The second chapter further expands and complements the introductory chapter, focusing on two elements: the concept of electronic commerce and its evolution from a general point of view, and the evolution of electronic commerce in Spain and main indicators of adoption. This section is intended to allow the reader to understand the research context, and also to serve as a basis to justify the relevance and representativeness of the sample used in this study. Chapters three (technology acceptance models) and four (segmentation in electronic commerce) set the theoretical foundations for the study. Chapter 3 presents a thorough literature review of technology adoption modelling, focusing on previous studies on electronic commerce acceptance. As a result of the literature review, the research framework is built upon a model based on UTAUT (Unified Theory of Acceptance and Use of Technology) and its evolution, UTAUT2, including two specific electronic commerce adoption factors: perceived risk and perceived trust. Chapter 4 deals with client and product segmentation methodologies used by experts. From the literature review, a wide range of classification variables is studied, and a shortlist of nine classification variables has been selected for inclusion in the research. The criteria for variable selection were their adequacy to electronic commerce characteristics, as well as adequacy to the sample characteristics. The nine variables have been classified in three groups: socio-demographic (gender, age, education level, income, family size and relationship status), behavioural (experience in electronic commerce and frequency of purchase) and psychographic (online purchase motivations) variables. The second half of chapter 4 is devoted to a review of the product classification criteria in electronic commerce. The review has led to the identification of a final set of fifteen groups of variables, whose combination offered a total of thirty-four possible outputs. However, due to the lack of empirical evidence in the context of electronic commerce, further investigation on the validity of this set of product classifications was deemed necessary. For this reason, chapter 5 proposes an empirical study to test the different product classification variables with 207 samples. A selection of product classifications including only those variables that are objective, able to identify distinct groups and not dependent on consumers’ point of view, led to a final classification of products which consisted on two groups of variables for the final empirical study. The combination of these two groups gave rise to four types of products: digital and non-digital goods, and digital and non-digital services. Chapter six characterizes the research –social, exploratory research– and presents the final research model and research hypotheses. The exploratory nature of the research becomes patent in instances where no prior empirical evidence on the influence of certain segmentation variables was found. Chapter six also includes the description of the measurement instrument used in the research, consisting of a total of 125 questions –and the measurement scales associated to each of them– as well as the description of the sample used for model validation (consisting of 817 Spanish residents). Chapter 7 is the core of the empirical analysis performed to validate the research model, and it is divided into two separate parts: description of the statistical techniques used for data analysis, and actual data analysis and results. The first part is structured in three different blocks: Partial Least Squares Method (PLS): the multi-variable analysis is a statistical method used to determine structural relationships of models and their predictive validity; Multi-group analysis: a set of techniques that allow comparing the outcomes of PLS analysis between two or more groups, by using one or more segmentation variables. More specifically, five comparison methods were used, which additionally gives the opportunity to assess the efficiency of each method. Determination of a priori undefined segments: in some cases, classification criteria did not necessarily exist for some segmentation variables, such as customer motivations. In these cases, the application of statistical classification techniques is required. For this study, two main classification techniques were used sequentially: principal component factor analysis –in order to reduce the number of variables– and cluster analysis. The application of the statistical methods to the models derived from the inclusion of the various segmentation criteria –for both clients and products–, led to the analysis of 128 different electronic commerce adoption models and 65 multi group comparisons. Finally, chapter 8 summarizes the conclusions from the research, divided into four parts: first, an assessment of the degree of achievement of the different research objectives is offered; then, methodological, theoretical and practical implications of the research are drawn; this is followed by a discussion on the results from the empirical study –based on the segmentation criteria for the research–; fourth, and last, the main limitations of the research –both empirical and theoretical– as well as future avenues of research are detailed.

Application of the agency theory for the analysis of performance-based mechanisms in road management

El WCTR es un congreso de reconocido prestigio internacional en el ámbito de la investigación del transporte, y aunque las actas publicadas están en formato digital y sin ISSN ni ISBN, lo consideramos lo suficientemente importante como para que se considere en los indicadores. This paper develops a model based on agency theory to analyze road management systems (under the different contract forms available today) that employ a mechanism of performance indicators to establish the payment of the agent. The base assumption is that of asymmetric information between the principal (Public Authorities) and the agent (contractor) and the risk aversion of this latter. It is assumed that the principal may only measure the agent?s performance indirectly and by means of certain performance indicators that may be verified by the authorities. In this model there is presumed to be a relation between the efforts made by the agent and the performance level measured by the corresponding indicators, though it is also considered that there may be dispersion between both variables that gives rise to a certain degree of randomness in the contract. An analysis of the optimal contract has been made on the basis of this model and in accordance with a series of parameters that characterize the economic environment and the particular conditions of road infrastructure. As a result of the analysis made, it is considered that an optimal contract should generally combine a fixed component and a payment in accordance with the performance level obtained. The higher the risk aversion of the agent and the greater the marginal cost of public funds, the lower the impact of this performance-based payment. By way of conclusion, the system of performance indicators should be as broad as possible but should not overweight those indicators that encompass greater randomness in their results.

A Knowledge Model for Automatic Configuration of Traffic Messages

This paper describes a knowledge model for a configuration problem in the do-main of traffic control. The goal of this model is to help traffic engineers in the dynamic selection of a set of messages to be presented to drivers on variable message signals. This selection is done in a real-time context using data recorded by traffic detectors on motorways. The system follows an advanced knowledge-based solution that implements two abstract problem solving methods according to a model-based approach recently proposed in the knowledge engineering field. Finally, the paper presents a discussion about the advantages and drawbacks found for this problem as a consequence of the applied knowledge modeling ap-proach.