The purpose of this thesis is to investigate the null subject phenomenon in the acquisition of English by Taiwan EFL learners to see whether the participants are influenced by their L1 knowledge or UG and whether they can reset their L1 value of null subject parameter. Two experimental tasks in questionnaire, grammaticality judgment task (GJ) and paragraph translation task (PT), and one oral task, storytelling task (ST), were adopted in this study. As for the participants, in the questionnaire part the GJ and PT tasks were given to 132 EFL learners, which were divided into the lower proficiency group (n=56) and the higher proficiency group (n=76), and 15 native speakers of English as a control group. Besides, we reanalyze the data of the ST task in Lin & Wu (2005), which consisted of 20 high English proficiency participants and 20 low English proficiency participants. Overall, the main findings are summarized as follows: 1. Chinese topic constructions seem to influence profoundly on the L2A of English by EFL learners. This may imply that L2 learners acquire the L2 through L1-based knowledge. 2. The asymmetry of null subjects and null objects was found in our data across the three tasks, which suggests EFL learners treated both features differently and have difficulty in unlearning null objects. We support Kong¡¦s (2005) claim that Chinese learners are influenced by L1 topic structure but they adjust this rule to: every sentence must have an overt topic in the sentence-initial position. 3. The different judgments between matrix and embedded clauses with null subjects and null expletives may infer EFL learners do not intrinsically reset the parameter of null subjects. 4. According to our results in ST task, there seems to be several patterns which make null subjects and null objects easier to occur, such as structures with coordinate relationship or clear reference relationship. These sentence patterns prove that the EFL learners are still easier to be influenced by the discourse-oriented feature in Chinese. According to the result, we may infer that the position of Partial Access to UG probably the best answer to our research questions since it is assumed that through Partial Access to UG, L2 learners will not be able to acquire the L2 values of parameters when these differ from the L1; that is, UG is accessible but only via the setting of the L1.

No description available.

As designers began to pack multi-million transistors onto a single chip, their reliance on a global clocking signal to orchestrate the operations of the chip has started to face almost insurmountable difficulties. As a result, designers started to explore clockless circuits to avoid the global clocking problem. Recently, self-resetting circuits implemented in dynamic logic families have been proposed as viable clockless alternatives. While these circuits can produce excellent performances, they display serious limitations in terms of area cost and power consumption. A middle-of-the-road alternative, which can provide a good performance and avoid the limitations seen in dynamic self-resetting circuits, would be to implement self-resetting behavior in static circuits. This alternative has been introduced recently as Self-Resetting Stage Logic and used to propose three types of clockless pipelines. Experimental studies show that these pipelines have the potential to produce high throughputs with a minimum area overhead if a suitable synthesis methodology is available. This thesis proposes a novel synthesis methodology to design and verify clockless pipelines implemented in SRSL by taking advantage of the maturity of current CAD tools. This methodology formulates the synthesis problem as a combinatorial analytical problem for which a run-time efficient exact solution is difficult to derive. Consequently, a two-phase algorithm is proposed to synthesize these pipelines from gate netlists subject to user-specified constraints. The first phase is a heuristic based on the as-soon-as-possible scheduling strategy in which each gate of the netlist is assigned to a single pipeline stage without violating the period constraint of each pipeline stage. On the other hand, the second phase consists of a heuristic, based on the Kernighan-Lin partitioning strategy, to minimize the number of nets crossing each pair of adjacent pipeline stages. The objective of this optimization is to reduce the number of latches separating pipeline stages since these latches tend to occupy large areas. Experiments conducted on a prototype of the synthesis algorithm reveal that these self-resetting stage logic pipelines can easily reach throughputs higher than 1 GHz. Furthermore, these experiments reveal that the area overhead needed to implement the self-resetting circuitry of these pipelines can be easily amortized over the area of the logic embedded in the pipeline stages. In the overall, the synthesis methods developed for SRSL produce low area overhead pipelines for wide and deep gate netlists while it tends to produce high throughput pipelines for wide and shallow gate netlists. This shows that these pipelines are mostly suitable for coarse-grain datapaths.

Synchronized neural activity, in which the firing of neurons is coordinated in time, is an observed phenomenon in many neural functions. The conditions that promote synchrony and the dynamics of synchronized activity are active areas of investigation because they are incompletely understood. In addition, variability is intrinsic to biological systems, but the effect of neuron spike time variability on synchronization dynamics is a question that merits more attention. Previous experiments using a hybrid circuit of one biological neuron coupled to one computational neuron revealed that irregularity in biological neuron spike timing could change synchronization in the circuit, transitioning the activity between phase-locked and phase slipping. Simulations of this circuit could not replicate the transitions in network activity if neuron period was represented as a Gaussian process, but could if a process with history and a stochastic component were used. The phase resetting curve (PRC), which describes how neuron cycles change in response to input, can be used to construct a map that predicts if synchronization will occur in hybrid circuits. Without modification, these maps did not always capture observed network activity. I conducted long-term recordings of invertebrate neurons and show that interspike interval (ISI) can be represented as an autoregressive integrated moving average process, where ISI is dependent on past history and a stochastic component with history. Using integrate and fire model simulations, I suggest that stochastic activity in adaptation channels could be responsible for the history dependence and correlational structure observed in these neurons. This evidence for stochastic, history-dependent noise in neural systems indicates that our understanding of network dynamics could be enhanced by including more complex, but relevant, forms of noise. I show that cycle-by-cycle dynamics of the coupled system can be used to infer features of the dynamic map, even if it cannot be measured or is changing over time. Using this method, stable fixed points can be distinguished from ghost attractors in the presence of noise, networks with similar phase but different underlying dynamics can be resolved, and the movement of stable fixed points can be observed. The time-series vector method is a valuable tool for distinguishing dynamics and describing robustness. It can be adapted for use in larger populations and non-reciprocal circuits. Finally, some larger implications of neuroscience research, specifically the use of neural interfaces for national security, are discussed. Neural interfaces for human enhancement in a national security context raise a number of unique ethical and policy concerns not common to dual use research of concern or traditional human subjects research. Guidelines about which technologies should be developed are lacking. We discuss a two-step framework with 1) an initial screen to prioritize technologies that should be reviewed immediately, and 2) a comprehensive ethical review regarding concerns for the enhanced individual, operational norms, and multi-use applications in the case of transfer to civilian contexts.

No description available.

No description available.

Cette thèse a pour objectif de décrire et d’analyser le rôle de la prosodie dans la structuration de l’énoncé en mooré (langue à ton parlée au Burkina Faso).Le problème majeur que je tente de résoudre dans ce travail est celui de la réalisation de l’intonation indicatrice de la structure prosodique dans les langues tonales. En d’autres termes, comment l’intonation se réalise-t-elle en mooré, une langue où le ton qui utilise les mêmes paramètres acoustiques doit garder son rôle phonologique ? Les explications détaillées du rôle et de la réalisation du ton et de l’intonation me permettent de déterminer une structure prosodique qui peut rendre compte de l’organisation du mooré parlé. D'un point de vue méthodologique, je m'inspire de la théorie de l'intonation de P. Martin, (2009, 2013, 2015), étant consciente qu’une certaine adaptation est nécessaire du fait de la nature de la langue étudiée.Cette thèse comporte deux parties : dans la première partie, je propose une définition des principaux termes de l’analyse et une présentation du mooré ; dans la deuxième, je m’appuie sur des études expérimentales pour analyser les principaux problèmes.Je m'intéresse, dans un premier temps à la réalisation phonétique du ton. Cette étude m'a permis de confirmer que la hauteur relative des tons est le paramètre le plus important pour distinguer les différents types de tons en mooré.Ensuite, l’examen de la relation entre ton et intonation révèle que la réalisation des tons lexicaux est affectée par celle de l’intonation surtout au niveau des frontières prosodiques. De plus dans l’abaissement tonal (downstep ou downdrift), la réalisation des tons est assujettie à la règle tonale, mais le domaine de l’abaissement est délimité par les frontières prosodiques, lieux de manifestation l’intonation.Enfin, l’étude sur la structuration des énoncés dans la parole lue et spontanée montre, à partir de l’identification d’évènements prosodiques, que les indices acoustiques tels que : la durée des pauses, l’allongement des syllabes finales et les variations de la fréquence fondamentale (F0) accompagnent les frontières perçues. Dans la parole lue, le resetting de F0 au début des unités et les variations de durée des syllabes de frontières prosodiques constituent les principaux indices de démarcation. Dans la parole spontanée, les résultats montrent qu’il y a une relation d’échange entre la durée des syllabes de frontières et celle des pauses et qu’elle s’associe aux variations de F0 pour permettre la structuration des énoncés en mooré / This dissertation describes the role of prosody in the organization of oral speech in Moore (a tone language spoken in Burkina Faso). It investigates the realization of intonation as a sign of prosodic structure in an African tone language. The main problem dealt in this study is: how does intonation work in moore, a tone language in which tone has already an important phonological role?The aim of the analysis is to explain the realization of tone and intonation in order to identify a prosodic structure which will account for the prosodic organization in moore. The theoretical framework is based on P. Martin’s theory of intonation in romance languages (2009, 2013, and 2015). Of course amendments were necessary to adapt it to moore.This dissertation is made up of two sections; the first one is dedicated to defining some important notions of the study and presenting general characteristics of moore. In the second section, experiments were carried out to address the main issues.The phonetic realization of tone was first examined. This study confirms that the relative height of the pitch is the main acoustic parameter used to distinguish the two types of tones in moore.Then the analysis of the relation between tone and intonation reveals that the realization of tones is affected by intonation especially at prosodic boundaries. When downstep is applied, tonal rules determine the realization of tones. However, the domain of the downstep is also marked out by prosodic boundaries (place of the realization of intonation).Finally, based on the identification of prosodic events, the study of moore oral speech (both spontaneous and reading speech) organization shows that acoustic parameters such as: duration of pauses, final syllable lengthening and F0 variations are found with perceived boundaries. The analysis of reading speech reveals that F0 resetting and variations of boundary syllables duration are the major indices which mark the limits of prosodic phrases. In spontaneous speech, the results suggest the existence of a trading relationship between pauses duration and boundary syllables duration. Therefore, the prosodic organization of utterances in moore derives from the combination of F0 variations and the trading relationship.

This dissertation introduces new methodologies for the analysis of neural spike trains. Biological properties of the nervous system, and how they are reflected in neural data, can motivate specific analytic tools. Some of these biological aspects motivate multiscale frameworks, which allow for simultaneous modelling of the local and global behaviour of neurons. Chapter 1 provides the preliminary background on the biology of the nervous system and details the concept of information and randomness in the analysis of the neural spike trains. It also provides the reader with a thorough literature review on the current statistical models in the analysis of neural spike trains. The material presented in the next six chapters (2-7) have been the focus of three papers, which have either already been published or are being prepared for publication. It is demonstrated in Chapters 2 and 3 that the multiscale complexity penalized likelihood method, introduced in Kolaczyk and Nowak (2004), is a powerful model in the simultaneous modelling of spike trains with biological properties from different time scales. To detect the periodic spiking activities of neurons, two periodic models from the literature, Bickel et al. (2007, 2008); Shao and Li (2011), were combined and modified in a multiscale penalized likelihood model. The contributions of these chapters are (1) employinh a powerful visualization tool, inter-spike interval (ISI) plot, (2) combining the multiscale method of Kolaczyk and Nowak (2004) with the periodic models ofBickel et al. (2007, 2008) and Shao and Li (2011), to introduce the so-called additive and multiplicative models for the intensity function of neural spike trains and introducing a cross-validation scheme to estimate their tuning parameters, (3) providing the numerical bootstrap confidence bands for the multiscale estimate of the intensity function, and (4) studying the effect of time-scale on the statistical properties of spike counts. Motivated by neural integration phenomena, as well as the adjustments for the neural refractory period, Chapters 4 and 5 study the Skellam process and introduce the Skellam Process with Resetting (SPR). Introducing SPR and its application in the analysis of neural spike trains is one of the major contributions of this dissertation. This stochastic process is biologically plausible, and unlike the Poisson process, it does not suffer from limited dependency structure. It also has multivariate generalizations for the simultaneous analysis of multiple spike trains. A computationally efficient recursive algorithm for the estimation of the parameters of SPR is introduced in Chapter 5. Except for the literature review at the beginning of Chapter 4, the rest of the material within these two chapters is original. The specific contributions of Chapters 4 and 5 are (1) introducing the Skellam Process with Resetting as a statistical tool to analyze neural spike trains and studying its properties, including all theorems and lemmas provided in Chapter 4, (2) the two fairly standard definitions of the Skellam process (homogeneous and inhomogeneous) and the proof of their equivalency, (3) deriving the likelihood function based on the observable data (spike trains) and developing a computationally efficient recursive algorithm for parameter estimation, and (4) studying the effect of time scales on the SPR model. The challenging problem of multivariate analysis of the neural spike trains is addressed in Chapter 6. As far as we know, the multivariate models which are available in the literature suffer from limited dependency structures. In particular, modelling negative correlation among spike trains is a challenging problem. To address this issue, the multivariate Skellam distribution, as well as the multivariate Skellam process, which both have flexible dependency structures, are developed. Chapter 5 also introduces a multivariate version of Skellam Process with Resetting (MSPR), and a so-called profile-moment likelihood estimation of its parameters. This chapter generalizes the results of Chapter 4 and 5, and therefore, except for the brief literature review provided at the beginning of the chapter, the remainder of the material is original work. In particular, the contributions of this chapter are (1) introducing multivariate Skellam distribution, (2) introducing two definitions of the Multivariate Skellam process in both homogeneous and inhomogeneous cases and proving their equivalence, (3) introducing Multivariate Skellam Process with Resetting (MSPR) to simultaneously model spike trains from an ensemble of neurons, and (4) utilizing the so-called profile-moment likelihood method to compute estimates of the parameters of MSPR. The discussion of the developed methodologies as well as the ``next steps'' are outlined in Chapter 7.

Made available in DSpace on 2016-04-29T13:17:49Z (GMT). No. of bitstreams: 1 Paulo Andre Barbosa Panetta.pdf: 927797 bytes, checksum: 1ff8351aa10bad0896b16ccf3e937863 (MD5) Previous issue date: 2013-07-01 / The production of delay of reinforcement with abstains of responses in the delay was studied with four rats. Four experiments were conducted, with one rat in each experiment, and a unique procedure for each study. It was planned an increase in one second upon the duration of the delay in Experiment I, after every three consecutive sessions without responding during the delays. In Experiment II, the delay of reinforcement was kept constant at eight seconds. Experiment III was identical to the previous one, except that the delay periods were signaled. The delay was also signaled in Experiment IV, with an increase of one second on it s duration after every three consecutive sessions without responding during the delay periods. It was only in the last experiment that the occurrence of three consecutive sessions without emissions on the delay periods was observed. This happed on Phases I and II, but not in Phase III. In some few sessions of Experiment I, there was no responding during reinforcement delay, but not for three consecutive sessions. In Experiments II and III, there was not a session without responding upon the delays periods. But it was recorded a reduction in the frequency of emissions during the sessions of both of the experiments, especially in Experiment II. The results indicate that, unless there is an explicit training, emissions will be recorded in the delay periods. The results were discussed from the procedures outlined for each experiment, focusing on the signal functions, the length of delay and the different effects between reinforcement delay resetting and non resetting / Quatro ratos participaram do estudo, que tinha como objetivo geral produzir períodos de atraso fixo de reforço non resetting, através de um treino com resetting, aumento gradual na duração do período de atraso e sinalização apresentada durante o período de atraso. O estudo foi dividido em quatro experimentos, com a participação exclusiva de um sujeito em cada. Foi delineado um procedimento distinto em cada experimento. No Experimento I, foi planejado um aumento de um segundo na duração do atraso de reforço a cada três sessões consecutivas sem emissões nos períodos de atraso. No Experimento II, a duração do atraso de reforço foi mantida constante em oito segundos, sem aumento gradual. O Experimento III foi idêntico ao anterior, com a diferença que os períodos de atraso eram sinalizados pela apresentação de som. No Experimento IV, foi planejado um aumento de um segundo na duração do atraso de reforço, sinalizado pela apresentação do som, a cada três sessões consecutivas sem emissões nos períodos de atraso de reforço. Nos resultados, foi observado apenas no ultimo experimento a ocorrência de três sessões consecutivas sem emissões nos períodos de atraso, durante as Fases Experimentais I e II. Porém, não na Fase Experimental III. Em algumas sessões do Experimento I, não ocorreram emissões durante o atraso de reforço, mas não por três sessões consecutivas. Nos Experimentos II e III, não houve o registro de uma sessão sem emissões nos períodos de atraso, mas foi registrado um redução na frequência de emissões ao longo das sessões dos experimentos, principalmente no Experimento II. Os resultados apontam que, caso não ocorra um treino explicito, emissões serão registradas nos períodos de atraso. Os resultados foram discutidos a partir dos procedimentos delineados para cada experimento, enfocando as funções da sinalização, a duração dos períodos de atraso e os efeitos distintos entre atraso de reforço non resetting e resetting

This thesis consists in the study of a periodically forced slow-fast system in both its excitable and oscillatory regimes. The slow-fast system under consideration is the FitzHugh-Nagumo model, and the periodic forcing consists of a train of Gaussian-shaped pulses, the width of which is much shorter than the action potential duration. This system is a qualitative model for both an excitable cell and a spontaneously beating cell submitted to periodic electrical stimulation. Such a configuration has often been studied in cardiac electrophysiology, due to the fact that it constitutes a simplified model of the situation of a cardiac cell in the intact heart, and might therefore contribute to the understanding of cardiac arrhythmias. Using continuation methods (AUTO software), we compute periodic-solution branches for the periodically forced system, taking the stimulation period as bifurcation parameter. We then study the evolution of the resulting bifurcation diagram as the stimulation amplitude is raised. In both the excitable and the oscillatory regimes, we find that a critical amplitude of stimulation exists below which the behaviour of the system is trivial: in the excitable case, the bifurcation diagram is restricted to a stable subthreshold period-1 branch, and in the oscillatory case, all the stable periodic solutions belong to isolated loops (i.e., to distinct closed solution branches). Due to the slow-fast nature of the system, the changes that take place in the bifurcation diagram as the critical amplitude is crossed are drastic, while the way the bifurcation diagram re-simplifies above some second amplitude is much more gentle. In the oscillatory case, we show that the critical amplitude is also the amplitude at which the topology of phase-resetting changes type. We explain the origin of this coincidence by considering a one-dimensional discrete map of the circle derived from the phase-resetting curve of the oscillator (the phase-resetting map), map which constitutes a good approximation of the original differential equations under certain conditions. We show that the bifurcation diagram of any such circle map, where the bifurcation parameter appears only in an additive fashion, is always characterized by the period-1 solutions belonging to isolated loops when the topological degree of the map is one, while these period-1 solutions belong to a unique branch when the topological degree of the map is zero.