Site-Directed Insertion: Decision Problems, Maximality and Minimality

Site-directed insertion is an overlapping insertion operation that can be viewed as analogous to the overlap assembly or chop operations that concatenate strings by overlapping a suffix and a prefix of the argument strings. We consider decision problems and language equations involving site-directed insertion. By relying on the tools provided by semantic shuffle on trajectories we show that one variable equations involving site-directed insertion and regular constants can be solved. We consider also maximal and minimal variants of the site-directed insertion operation

Decomposition and Descriptional Complexity of Shuffle on Words and Finite Languages

We investigate various questions related to the shuffle operation on words and finite languages. First we investigate a special variant of the shuffle decomposition problem for regular languages, namely, when the given regular language is the shuffle of finite languages. The shuffle decomposition into finite languages is, in general not unique. Thatis,therearelanguagesL^,L2,L3,L4withLiluL2= £3luT4but{L\,L2}^ {I/3, L4}. However, if all four languages are singletons (with at least two combined letters), it follows by a result of Berstel and Boasson [6], that the solution is unique; that is {L\,L2} = {L3,L4}. We extend this result to show that if L\ and L2 are arbitrary finite sets and Lz and Z-4 are singletons (with at least two letters in each), the solution is unique. This is as strong as it can be, since we provide examples showing that the solution can be non-unique already when (1) both L\ and L2 are singleton sets over different unary alphabets; or (2) L\ contains two words and L2 is singleton. We furthermore investigate the size of shuffle automata for words. It was shown by Campeanu, K. Salomaa and Yu in [11] that the minimal shuffle automaton of two regular languages requires 2mn states in the worst case (where the minimal automata of the two component languages had m and n states, respectively). It was also recently shown that there exist words u and v such that the minimal shuffle iii DFA for u and v requires an exponential number of states. We study the size of shuffle DFAs for restricted cases of words, namely when the words u and v are both periods of a common underlying word. We show that, when the underlying word obeys certain conditions, then the size of the minimal shuffle DFA for u and v is at most quadratic. Moreover we provide an efficient algorithm, which decides for a given DFA A and two words u and v, whether u lu u C L(A)

Complexity and modeling power of insertion-deletion systems

SISTEMAS DE INSERCIÓN Y BORRADO: COMPLEJIDAD Y CAPACIDAD DE MODELADO El objetivo central de la tesis es el estudio de los sistemas de inserción y borrado y su capacidad computacional. Más concretamente, estudiamos algunos modelos de generación de lenguaje que usan operaciones de reescritura de dos cadenas. También consideramos una variante distribuida de los sistemas de inserción y borrado en el sentido de que las reglas se separan entre un número finito de nodos de un grafo. Estos sistemas se denominan sistemas controlados mediante grafo, y aparecen en muchas áreas de la Informática, jugando un papel muy importante en los lenguajes formales, la lingüística y la bio-informática. Estudiamos la decidibilidad/ universalidad de nuestros modelos mediante la variación de los parámetros de tamaño del vector. Concretamente, damos respuesta a la cuestión más importante concerniente a la expresividad de la capacidad computacional: si nuestro modelo es equivalente a una máquina de Turing o no. Abordamos sistemáticamente las cuestiones sobre los tamaños mínimos de los sistemas con y sin control de grafo.COMPLEXITY AND MODELING POWER OF INSERTION-DELETION SYSTEMS The central object of the thesis are insertion-deletion systems and their computational power. More specifically, we study language generating models that use two string rewriting operations: contextual insertion and contextual deletion, and their extensions. We also consider a distributed variant of insertion-deletion systems in the sense that rules are separated among a finite number of nodes of a graph. Such systems are refereed as graph-controlled systems. These systems appear in many areas of Computer Science and they play an important role in formal languages, linguistics, and bio-informatics. We vary the parameters of the vector of size of insertion-deletion systems and we study decidability/universality of obtained models. More precisely, we answer the most important questions regarding the expressiveness of the computational model: whether our model is Turing equivalent or not. We systematically approach the questions about the minimal sizes of the insertiondeletion systems with and without the graph-control

Neuropsychological Instruction: A Process Related Approach in Early Reading Skill Development

Proficient and fluent reading ability for all Americans continues to be a highly prioritized, yet under achieved aspiration in current educational institutions. The acquisition of proficient reading fluency and comprehension are, undoubtedly, the most essential priorities in the academic development of school aged children, yet a discouraging number of students continue to struggle with the reading process throughout school aged years. Research has targeted key instructional areas that must be implemented in successful reading curriculum in the early childhood years. Namely, phonological awareness, phonics instruction, reading fluency, vocabulary development, and reading comprehension are core components that must be incorporated into literacy curricula and mastered by students as instruction is occurring in order to drive successful, long term reading outcomes. Advances in neurological research have added to current knowledge regarding how a child’s brain develops proficient reading ability. Neural networks are formed to create language systems, while brain plasticity in the first seven years of life allows for developmental manipulation. Despite these advances in knowledge and research, reading intervention continues to be reactive, and is usually applied after a student has fallen behind age expected benchmarks. There is a need for current research to demonstrate proactive methods to support successful literacy outcomes from the start of formal instruction, thereby thwarting the phenomenon of reading failure, and increasing reading proficiency for more students. Archival data were obtained from a program evaluation utilizing a pre/post test experimental design to measure reading gains for regular education Kindergarten students receiving balanced literacy instruction. The data were further examined to determine if students receiving balanced literacy instruction, in addition to the use of the PAL II Guides for Intervention as a proactive twelve week supplement to regular instruction, would realize greater gains in reading readiness than those students receiving balanced literacy instruction alone. All students (N = 31) who participated in the program evaluation were randomly assigned to one of two groups and received pre and post assessments in pre reading skill development. Findings indicate the use of a quality based, balanced literacy program does result in gains for writing legibility and speed; copying automaticity, legibility, and speed; receptive coding ability; auditory and verbal rhyming of words; phoneme segmentation and phoneme deletion; and syllable manipulation. Findings further indicate that the combined use of balanced literacy and the PAL II supplemental intervention yielded significant gains in writing automaticity, legibility and speed; copying automaticity, legibility, and speed; receptive coding; auditory and verbal rhyming of words; phoneme segmentation and phoneme deletion; syllabic manipulation; and verbal working memory. In an examination of the amount of measurable growth, those students receiving the PAL II supplement in addition to the balanced literacy program, made more statistically significant incremental gains than the group receiving balanced literacy alone in nine of the thirteen pre-reading skill variables. Medium effect sizes were noted for the balanced literacy plus intervention group over the balanced literacy group for writing automaticity, writing legibility, and copying automaticity. Large effect sizes were noted for the balanced literacy plus intervention group over the balanced literacy group for copying legibility, receptive coding, rhyming, syllables, phonemes, and verbal working memory. A small effect size was noted in writing speed but no effect size was noted for copying speed. These findings lend support to current research that emphasizes the importance of developing successful pre-reading skill acquisition in the early childhood years via the proactive use of quality instruction and supplemental intervention. Research further denotes the importance of early instruction while critical neural development is occurring in young learner’s language systems. Results from this study support this finding, and can be utilized as a proactive strategy to enhance learning for all students at the beginning of formal school instruction. By doing so, more young students are likely to develop improved mastery of the skills needed to become successful future readers, and fewer students will be left to struggle with reading skill development throughout school aged years

Context Modulated Spatial Encoding and Memory Consolidation in the Rodent Hippocampus

The recollection of daily events is inherently personal: episodic memories are defined by the recollection of one’s sense of self during a particular event, within a surrounding context. Representations of such experiences are initially encoded in the hippocampus then consolidated by their repeated reactivation in synchrony with the cortex during sleep. After consolidation, memories are less prone to interference by similar experiences. However, a day in one’s life is usually constructed from multiple episodic experiences which can span multiple contexts. Little is known about the potential interference by previous memories on the construction of novel representations when contextual features are shared. Moreover, salient episodic memories are better remembered than neutral ones in the long term. Highly rewarding, traumatic or novel experiences can lead to intrusive (e.g. Post Traumatic Stress Disorder) or extremely vivid recall (e.g. Flashbulb memories) recall, and in general longer lasting memories. This phenomenon of prioritised memory consolidation is thought to ensure the storage of relevant memories, at the detriment of less important ones, and has been shown to correlate with an overall increase in their reactivation frequency during sleep. However, the temporal dynamics of memory triage during sleep have not yet been investigated. Recording from many hippocampal neurons simultaneously in the rat, during both sleep and the exploration of three completely new environments each session, we tracked the encoding and consolidation of feature-sharing and salience modulated representations. We provide evidence for the presence of neural patterns of activity that may support generalisation with similar past experiences, as well as differentiation of the novel representation during its initial stabilisation window. Furthermore, we show that the temporal dynamics of memory triage are not uniform, and instead exhibit a cyclic (time attributed to each memory) and an amplitude (relative proportion) component

Privacy and trustworthiness management in moving object environments

The use of location-based services (LBS) (e.g., Intel\u27s Thing Finder) is expanding. Besides the traditional centralized location-based services, distributed ones are also emerging due to the development of Vehicular Ad-hoc Networks (VANETs), a dynamic network which allows vehicles to communicate with one another. Due to the nature of the need of tracking users\u27 locations, LBS have raised increasing concerns on users\u27 location privacy. Although many research has been carried out for users to submit their locations anonymously, the collected anonymous location data may still be mapped to individuals when the adversary has related background knowledge. To improve location privacy, in this dissertation, the problem of anonymizing the collected location datasets is addressed so that they can be published for public use without violating any privacy concerns. Specifically, a privacy-preserving trajectory publishing algorithm is proposed that preserves high data utility rate. Moreover, the scalability issue is tackled in the case the location datasets grows gigantically due to continuous data collection as well as increase of LBS users by developing a distributed version of our trajectory publishing algorithm which leveraging the MapReduce technique. As a consequence of users being anonymous, it becomes more challenging to evaluate the trustworthiness of messages disseminated by anonymous users. Existing research efforts are mainly focused on privacy-preserving authentication of users which helps in tracing malicious vehicles only after the damage is done. However, it is still not sufficient to prevent malicious behavior from happening in the case where attackers do not care whether they are caught later on. Therefore, it would be more effective to also evaluate the content of the message. In this dissertation, a novel information-oriented trustworthiness evaluation is presented which enables each individual user to evaluate the message content and make informed decisions --Abstract, page iii

Long-term stability of the hippocampal neural code as a substrate for episodic memory

The hippocampus supports the initial formation and recall of episodic memories, as well as the consolidation of short-term into long-term memories. The ability of hippocampal neurons to rapidly change their connection strengths during learning and maintain these changes over long time-scales may provide a mechanism supporting memory. However, little evidence currently exists concerning the long-term stability of information contained in hippocampal neuronal activity, likely due to limitations in recording extracellular activity in vivo from the same neurons across days. In this thesis I employ calcium imaging in freely moving mice to longitudinally track the activity of large ensembles of hippocampal neurons. Using this technology, I explore the proposal that long-term stability of hippocampal information provides a substrate for episodic memory in three different ways. First, I tested the hypothesis that hippocampal activity should remain stable across days in the absence of learning. I found that place cells – hippocampal neurons containing information about a mouse’s position – maintain a coherent map relative to each other across long time-scales but exhibit instability in how they anchor to the external world. Furthermore, I found that coherent maps were frequently used to represent a different environment and incorporated learning via changes in a subset of neurons. Next, I examined how learning a spatial alternation task impacts neuron stability. I found that splitter neurons whose activity patterns reflected an animal’s future or past trajectory emerged relatively slowly when compared to place cells. However, splitter neurons remained more consistently active and relayed more consistent spatial information across days than did place cells, suggesting that the utility of information provided by a neuron influences its long term stability. Last, I investigated how protein synthesis, known to be necessary for long-term maintenance of changes in hippocampal neuron connection strengths and for proper memory consolidation, influences their activity patterns across days. I found that along with blocking memory consolidation, inhibiting protein synthesis induced a profound, long-lasting decrease in neuronal activity up to two days later. These results combined demonstrate the importance of rapid, lasting changes in the hippocampal neuronal code to supporting long-term memory