Investigation of the development of neural and behavioural auditory rhythmic sensitivity and of its contribution to reading acquisition

241 p.The main goal of the current doctoral dissertation was to examine the contribution of brain and behavioural rhythmic sensitivity during pre-reading stages to the development of future reading. To achieve this goal, we conducted a longitudinal study in which typically developing children were tested three times: twice before they had received formal reading instruction (T1: 4-5 y.o.; T2: 5-6 y.o.) and once after reading instruction was introduced in the school curriculum (T3: 6-7 y.o.). Along these three testing times, we used EEG to measure the children¿s brain rhythmic (oscillatory) activity in response to natural speech and to auditory signals modulated at rates relevant for speech perception (at the stress, syllabic and phonemic rates). The children also ran a battery of behavioural tasks that included a measure of rhythmic skills (tapping to a beat in synchrony) and several classical reading predictors (e.g. phonological awareness, phonological short-term memory). The longitudinal nature of this work allowed us testing for the first time the trajectory of brain coherence to auditory signals during early childhood. Furthermore, this is the first study finding a long-hypothesized relation between brain oscillatory activity at low frequency bands (0.5 Hz) in pre-reading stages and later reading achievement, such that right-lateralized brain responses to speech at T2 correlated significantly with children¿s reading achievement at T3. Regarding behavioural rhythm sensitivity, whereas rhythmic skills were tightly related to other reading predictors before reading was acquired (T1 and T2), we found no evidence that it contributed significantly to final reading outcome. Differences among measures of brain vs. behavioural rhythmic sensitivity are discussed, especially in the context of early detection and intervention of children at risk of developing reading disorders.bcbl: basque center on cognition, brain and languag

Investigation of the development of neural and behavioural auditory rhythmic sensitivity and of its contribution to reading acquisition

241 p.The main goal of the current doctoral dissertation was to examine the contribution of brain and behavioural rhythmic sensitivity during pre-reading stages to the development of future reading. To achieve this goal, we conducted a longitudinal study in which typically developing children were tested three times: twice before they had received formal reading instruction (T1: 4-5 y.o.; T2: 5-6 y.o.) and once after reading instruction was introduced in the school curriculum (T3: 6-7 y.o.). Along these three testing times, we used EEG to measure the children¿s brain rhythmic (oscillatory) activity in response to natural speech and to auditory signals modulated at rates relevant for speech perception (at the stress, syllabic and phonemic rates). The children also ran a battery of behavioural tasks that included a measure of rhythmic skills (tapping to a beat in synchrony) and several classical reading predictors (e.g. phonological awareness, phonological short-term memory). The longitudinal nature of this work allowed us testing for the first time the trajectory of brain coherence to auditory signals during early childhood. Furthermore, this is the first study finding a long-hypothesized relation between brain oscillatory activity at low frequency bands (0.5 Hz) in pre-reading stages and later reading achievement, such that right-lateralized brain responses to speech at T2 correlated significantly with children¿s reading achievement at T3. Regarding behavioural rhythm sensitivity, whereas rhythmic skills were tightly related to other reading predictors before reading was acquired (T1 and T2), we found no evidence that it contributed significantly to final reading outcome. Differences among measures of brain vs. behavioural rhythmic sensitivity are discussed, especially in the context of early detection and intervention of children at risk of developing reading disorders.bcbl: basque center on cognition, brain and languag

Excitons and biexcitons in symmetric electron-hole bilayers

Symmetric electron-hole bilayer systems have been studied at zero temperature using the diffusion quantum Monte Carlo method. A flexible trial wave function is used that can describe fluid, excitonic and biexcitonic phases. We calculate condensate fractions and pair correlation functions for a large number of densities rs and layer separations d. At small d we find a one-component fluid phase, an excitonic fluid phase, and a biexcitonic fluid phase, and the transitions among them appear to be continuous. At d = 0, excitons appear to survive down to about rs = 0.5 a.u., and biexcitons form at rs > 2.5 a.u.Comment: 5 pages, 4 figure

Diego de Valera y la literatura de mirabilia. El "Liber de Natura Rerum" de Tomás de Cantimpré como fuente de la "Crónica Abreviada".

Este trabajo demuestra que una de las fuentes empleadas por Diego de Valera en la primera parte de su "Crónica abreviada de España" conocida también como la "Valeriana" es el "Liber de Natura Rerum" de Tomás de Cantimpré. El cotejo del texto latino con el castellano no deja lugar a dudas

El concepto de «salvaje» en la Edad Media española: AIgunas consideraciones.

Sin resume

Evaluation of PUF and QKD integration techniques as root of trust in communication systems

Quantum Cryptography could be the next key technology in terms of secure communication, but, as with every new technology, it presents problems that need to be solved in order to become a reality in daily life. This work discusses the integration of Physical Unclonable Functions (PUFs) as a solution for the authentication of the endpoints in quantum communication protocols. The use of PUF constructions would allow the authentication of devices without the need of relying on third parties, and support switched trustworthy quantum communication channels; two unseen features in Quantum Key Distribution (QKD) until now. We analyze in detail PUF integration within the BB84 protocol, as it is the foundation for all QKD protocols, and two proposals for an authentication scheme are made, depending on the connection characteristics of the communication endpoints and the distance between them. These proposals are then generalized for other types of QKD protocol. Moreover, different types of PUF are analyzed to conclude which ones are the most suitable for our purpose.La Criptografía Cuántica podría ser la próxima tecnología clave en relación a la seguridad de las comunicaciones pero, como toda nueva tecnología, presenta problemas que deben ser resueltos antes de llegar a ser una realidad en el día a día. Este trabajo discute la integración de Funciones Físicas No-Clonables (PUFs, por sus siglas en inglés) como solución a la autenticación de los extremos en un protocolo de comunicación cuántica. El uso de PUFs permitiría la autenticación de dispositivos sin necesidad de depender de terceros, además de abrir la posibilidad a la conmutación de canales de comunicación cuántica; dos características nunca vistas en la Distribución Cuántica de Claves (QKD, por sus siglas en inglés) hasta ahora. Se analiza en detalle la integración de PUFs en el protocolo BB84, ya que es la base de todos los protocolos de QKD, y se proponen dos esquemas de autenticación distintos, atendiendo a las características de los extremos de la comunicación y la distancia entre ellos. Después, estas propuestas se generalizan para el resto de protocolos de QKD. Además, se estudian distintos tipos de PUF con el objeto de encontrar la más adecuada para nuestro propósito.Universidad de Sevilla. Grado en Físic