Until recently, transit data lacked a common data format that could be used to share and integrate information among multiple agencies. In 2005, however, Google worked with Tri-Met in Oregon to create the General Transit Feed Specification (GTFS), an open data format now used by all transit agencies that participate in Google Maps. GTFS feeds contain data for scheduled transit service including stop and route locations, schedules and fare information. The broad adoption of GTFS by transit agencies has made it a de facto standard. Those agencies using it are able to participate in a host of traveler services designed for GTFS, most notably transit trip planners. Still, analysts have not widely used GTFS as a data source for transit planning because of the newness of the technology. The objectives of this project are to demonstrate that GTFS feeds are an efficient data source for calculating key transit service metrics and to evaluate the validity of GTFS feeds as a data source. To demonstrate GTFS feeds’ analytic potential, the author created a tool called GTFS Reader, which imports GTFS feeds into a database using open-source products. GTFS Reader also includes a series of queries that calculate metrics like headways, route lengths and stop-spacing. To evaluate the validity of GTFS feeds, annual vehicle revenue miles and hours from the National Transit Database (NTD) are compared to the calculated values from agencies whose GTFS feeds are available. The key finding of this work is that well-formed GTFS feeds are an accurate representation of transit networks and that the method of aggregation presented in this research can be used to effectively and efficiently calculate metrics for transit agencies. The daily aggregation method is more accurate than the weekly aggregation method, both introduced in this thesis, but practical limitations on processing time favor the weekly method. The reliability of GTFS feed data for smaller agencies is less conclusive than that of larger agencies because of discrepancies found in smaller agencies when their GTFS-generated metrics were compared to those in the NTD. This research will be of particular interest to transit and policy analysts, researchers and transit planners.

In this thesis the structure of the nominal group in Black South African English (BSAfE) is investigated by means of a comparison of data from the Tswana Learner English Corpus (TLEC) and the Louvain Corpus of Native English Essays (LOCNESS). Both corpora consist of student essays and are sub-corpora of the International Corpus of Learner English (ICLE). The TLEC represents a non-native variety of English, namely BSAfE, while LOCNESS represents native English from the United States and the United Kingdom. In the existing literature there are observations about and examples of (non-standard) characterizing features of BSAfE pertaining to nouns, determiners and quantifiers (e.g. Gough 1996), but until now, no in-depth study of the grammar of the nominal group in BSAfE has been undertaken. This study is an attempt to fill that gap. I present a description of the grammatical features of BSAfE observed in the corpus data in terms of linguistic functions and without assuming that they are errors or evidence of deficiencies. Though the approach is comparative (in the sense that a control corpus is used), it is primarily descriptive and non-normative, and as such, function-based. This study is conducted within the theoretical framework of functional linguistics, drawing on systemic functional linguistics as well as other functional and cognitive approaches to language. The specifying functions that the nominal group and its elements may fulfill form the basis of the descriptive framework. These functions are (1) the type-specifying function of the noun, (2) the (referent-)specifying function of the determiner, (3) quantification and (4) quality specification by modifiers and complements. The type-specifying function of the noun is particularly relevant in Chapter 4, which deals with the grammatical patterns of the noun people, although it also informs analyses in Chapters 5 and 6 which deal with determiners and quantification respectively. Quality specification is especially relevant in the description of the grammatical patterns of the noun people. The noun people is the most frequent noun in each of the corpora, but is at the same time a positive keyword in the TLEC, which means that it occurs much more frequently in the TLEC than in LOCNESS. Analysis of the full corpus concordances of this noun provides much evidence of anti-deletion in BSAfE (as first postulated by Mesthrie, 2006) and also sheds some light on left dislocation patterns involving the noun people (cf. Mesthrie, 1997). This analysis also reveals unique uses of the definite article and certain quantifying constructions in the TLEC data, which are investigated in the next two analysis chapters. A comparison of concordance samples of the articles indicates that the definite/indefinite distinction is made in both corpora and that there is not enough corpus evidence to postulate that there is a different system underlying the choice of article in BSAfE, such as a system based principally on the specific/non-specific distinction, as postulated by Platt, Weber and Ho (1984) for New Englishes in general. Analysis of the concordances of demonstrative and possessive determiners indicate that these determiners are used proportionally more frequently in the TLEC than in LOCNESS. Concordances of the words that are normally classified as quantifiers indicate that there are many more partitive-of quantifying constructions in the TLEC than in LOCNESS. The words some and most are positive keywords in the TLEC. After analyses of their concordances, it is concluded that their relative frequency can be attributed to the fact that some is often used merely as an indefinite marker and that most is often used as a synonym for many. The study shows that BSAfE largely shares its general grammar of the nominal group with other (including native) varieties of English, but at a finer level of analysis, some characteristic constructions and uses are detected. The corpus data indicate that the unique constructions in the TLEC data are mostly functionally motivated. These constructions represent conventionalized innovations in the sense used by Van Rooy (2010), rather than mere language learning errors. / Thesis (PhD (Linguistics and Literary Theory))--North-West University, Potchefstroom Campus, 2012

This thesis describes the design and deployment of netLab, a self-contained lab environment suitable for use in an upper level networking course. NetLab does not require special hardware, special permissions, kernel modifications, or multiple computers. The laboratory was designed to emphasize hands-on programming over device configuration or performance analysis. NetLab uses network engineering projects to motivate software engineering principles. The main projects are linkLab and routerLab, the implementations of a layer-2 network protocol and a layer-3 routing algorithm simulation. Both projects use a physical-layer emulator providing controllable impairment for thorough testing. The lab has been shown to be capable of expansion to accommodate different protocols. NetLab is a success in that students consistently found netLab to be challenging and exciting, and all ranks of students advanced their skills.

The specification of a decoder, i.e., a program that translates sentences from one natural language into another, is an intricate process, driven by the application and lacking a canonical methodology. The practical nature of decoder development inhibits the transfer of knowledge between theory and application, which is unfortunate because many contemporary decoders are in fact related to formal-language theory. This thesis proposes an algebraic framework where a decoder is specified by an expression built from a fixed set of operations. As yet, this framework accommodates contemporary syntax-based decoders, it spans two levels of abstraction, and, primarily, it encourages mutual stimulation between the theory of weighted tree automata and the application.

Le travail présenté dans cette thèse porte sur le rôle du cortex prémoteur dorsal (PMd) au sujet de la prise de décision (sélection d’une action parmis nombreux choix) et l'orientation visuelle des mouvements du bras. L’ouvrage décrit des expériences électrophysiologiques chez le singe éveillé (Macaca mulatta) permettant d’adresser une fraction importante des prédictions proposées par l'hypothèse des affordances concurrentes (Cisek, 2006; Cisek, 2007a). Cette hypothèse suggère que le choix de toute action est l’issue d'une concurrence entre les représentations internes des exigences et des atouts de chacune des options présentées (affordances; Gibson, 1979). Un intérêt particulier est donné au traitement de l'information spatiale et la valeur des options (expected value, EV) dans la prise de décisions. La première étude (article 1) explore la façon dont PMd reflète ces deux paramètres dans la période délai ainsi que de leur intéraction. La deuxième étude (article 2) explore le mécanisme de décision de façon plus détaillée et étend les résultats au cortex prémoteur ventral (PMv). Cette étude porte également sur la représentation spatiale et l’EV dans une perspective d'apprentissage. Dans un environnement nouveau les paramètres spatiaux des actions semblent être présents en tout temps dans PMd, malgré que la représentation de l’EV apparaît uniquement lorsque les animaux commencent à prendre des décisions éclairées au sujet de la valeur des options disponibles. La troisième étude (article 3) explore la façon dont PMd est impliqué aux “changements d'esprit“ dans un procès de décision. Cette étude décrit comment la sélection d’une action est mise à jour à la suite d'une instruction de mouvement (GO signal). I II Les résultats principaux des études sont reproduits par un modèle computationnel (Cisek, 2006) suggérant que la prise de décision entre plusieurs actions alternatives peux se faire par voie d’un mécanisme de concurrence (biased competition) qui aurait lieu dans la même région qui spécifie les actions. / This thesis examines the role of the dorsal premotor cortex (PMd) in the process of decision making (action selection) and visual guidance of arm movements. The work describes electrophysiological experiments conducted in awake monkeys (Macaca mulatta) and tests a number of important predictions suggested by the affordance competition hypothesis (Cisek, 2006; Cisek, 2007a). This hypothesis suggests that decisions can be viewed as the result of a competition between internal representations of conflicting demands and opportunities for actions or affordances (Gibson, 1979). Specific interest is given to the interaction between spatial information and expected value (EV) in a proposed affordance competition mechanism for action selection. The first study presented (article 1) explores how EV is represented during the delay period in PMd. This study also describes how this area reflects the spatial metrics of the options and examines the interaction between value and spatial information. The second study (article 2) explores the mechanism of action selection in more detail and extends the results to ventral premotor cortex (PMv). This study also addresses the nature of value and spatial representations from a learning perspective. In a novel environment the spatial metrics of the actions seem to be invariably present in PMd, meanwhile EV representations appear only once the animals make behaviorally informed decisions about the value of the available options. The third study (article 3) explores how PMd is involved in “changes of mind” in which action selection is updated following a movement instruction (GO signal). III IV The major findings in all these studies are reproduced by a computational model (Cisek, 2006) suggesting that decisions between actions can be made through a biased competition process that takes place in the same region that specifies the actions.

The thesis "Four Essays on the Econometric Modelling of Volatility and Durations" consists of four research papers in the area of financial econometrics on topics of the modelling of financial market volatility and the econometrics of ultra-high-frequency data. The aim of the thesis is to develop new econometric methods for modelling and hypothesis testing in these areas. The second chapter introduces a new model, the time-varying GARCH (TV-GARCH) model, in which volatility has a smooth time-varying structure of either additive or multiplicative type. To characterize smooth changes in the (un)conditional variance we assume that the parameters vary smoothly over time according to the logistic transition function. A data-based modelling technique is used for specifying the parametric structure of the TV-GARCH models. This is done by testing a sequence of hypotheses by Lagrange multiplier tests presented in the chapter. Misspecification tests are also provided for evaluating the adequacy of the estimated model. The third chapter addresses the issue of modelling deterministic changes in the unconditional variance over a long return series. The modelling strategy is illustrated with an application to the daily returns of the Dow Jones Industrial Average (DJIA) index from 1920 until 2003. The empirical results sustain the hypothesis that the assumption of constancy of the unconditional variance is not adequate over long return series and indicate that deterministic changes in the unconditional variance may be associated with macroeconomic factors. In the fourth chapter we propose an extension of the univariate multiplicative TV-GARCH model to the multivariate Conditional Correlation GARCH (CC-GARCH) framework. The variance equations are parameterized such that they combine the long-run and the short-run dynamic behaviour of the volatilities. In this framework, the long-run behaviour is described by the individual unconditional variances, and it is allowed to vary smoothly over time according to the logistic transition function. The effects of modelling the nonstationary variance component are examined empirically in several CC-GARCH models using pairs of seven daily stock return series from the S&P 500 index. The results show that the magnitude of such effect varies across different stock series and depends on the structure of the conditional correlation matrix. An important feature of financial durations is the evidence of a strong diurnal variation over the trading day. In the fifth chapter we propose a new parameterization for describing the diurnal pattern of trading activity. The parametric structure of the diurnal component allows the duration process to change smoothly over the time-of-day according to the logistic transition function. The empirical results suggest that the diurnal variation may not always have the inverted U-shaped pattern for the trade durations as documented in earlier studies.

To determine the economic design of control charts and the specification limits with minimum cost are two separate issues in previous research areas. In this study, we proposed a method to determine the optimal design parameters of X control charts and the specification limits simultaneously from an economic viewpoint. We also consider two types of X control charts: one is the economic X control chart and the other is the economic statistical X control chart. We obtain the optimal results by minimizing the expected cost per unit time for the-larger-the-better quality characteristic with a Weibull distribution. We consider the asymmetric control limits because of the asymmetric feature of theWeibull distribution. Also, we are considering the difference between monitoring the process by using an economic statistical X control chart and conducting a complete inspection plan. Which way is better, process control or inspection plan? In our data analysis of the two types of X control chart, we find that the optimal expected cost per unit time with complete inspection is lower than without complete inspection. This is because the coefficient of Taguchi’s quadratic loss function we set is too small. And the analysis shows us the significant parameters for the optimal expected cost per unit time and design parameters. At last, in our numerical examples for two different types of X control chart, we find that the performance of the economic X control chart is as good as the economic statistical one. However, we suggest the producer use the economic statistical X control chart with a complete inspection plan to obtain a lower expected cost per unit time and larger power of the control chart.

Pluripotent cells are unique due to their developmental potential and the possibility to study them is the key step to understand human development. These cells are characterized by their ability to originate all the cellular lineages within an adult organism. Within embryonic milieu, pluripotent cells represent a dynamic fraction of the total cell number. Moreover, their physiological existence is constrained to early stages of embryonic development. In vitro culture of the different types of mammalian pluripotent cells, and singularly embryonic stem cells (ESC), enables the characterization of the pluripotent state. In the four articles included in this thesis we have addressed two different aspects of the molecular characterization of mammalian pluripotent cells. First, we investigated the establishment of the trophectoderm and the inner cell mass in the embryo measuring transcript abundance and protein presence of the transcription factors known to play a role in the earliest cellular differentiation process. In addition we have evaluated of genomic stability of human ESC lines during long-term culture, observing the accumulation of sukaryotypic aberrations such as loss of heterozygosity that affect loci comprising genes involved in genomic stability maintenance. We also checked the genomic status of two human ESC lines derived from embryos that had been diagnosed as abnormal after genetic preimplantation diagnosis (PGD). The molecular analysis of these cells ruled out the hypothesized self-correction of the aneuploidies between the PGD and the establishment of the cell lines. / Les cèl·lules pluripotents són úniques atesa la seva plasticitat durant el desenvolupament i la possibilitat d'estudiar-les és un pas essencial per poder comprendre el desenvolupament embrionari. Aquestes cèl·lules es caracteritzen per la seva habilitat per donar lloc a tots els llinatges cel·lulars de l'organisme. Dins de l'embrió, les cèl·lules pluripotents representen una fracció dinàmica del nombre total de cèl·lules i la seva existència fisiològica està constreta a els estadis més primerencs del desenvolupament embrionari. El cultiu in vitro dels diferents tipus de cèl·lules pluripotents en mamífers, i en especial les cèl·lules mare embrionàries, permet la caracterització d'aquest estat cel·lular. En els quatre capítols inclosos en aquesta tesi, hem tractat dos aspectes diferents de la caracterització molecular de les cèl·lules pluripotents. Primer, hem investigat l'establiment del trofectoderm i de la massa cel·lular interna en l'embrió mesurant l'abundància dels trànscrits i la presència de proteina dels factors de transcripció implicats en el primer process de diferenciació cel·lular conegut. A més, hem avaluat l'estabilitat genòmica de dues línies de cèl·lules mare en cultiu durant més de 40 passis. Com a resultat, hem observat l'acumulació de aberracions genòmiques a nivell subcariotípic, en especial pèrdua d'heterozigositat que afecta a locus que contenen gens implicats en el manteniment de l'estabilitat genòmica. També hem comprovat l'estatus genòmic de dos linies de cèl·lules mare embrionàries humanes derivades a partir d'embrions trobats aneuploids per un diagnòstic genètic preimplantacional. L'anàlisi molecular d'aquestes cèl·lules va descartar la hipòtesi d'una autocorrecció de les aneuploidies detectades entre el diagnòstic preimplantacional i la derivació de les línies a partir d'aquests embrions.

Currently, the bulk of applications of Formal Concept Analysis (FCA) in software engineering have focussed on software maintenance and re-engineering. In this thesis we broaden the approach by applying FCA to a number of early-phase activities within the software engineering life-cycle. With respect to the requirements engineering phase, a case study is presented comparing two class hierarchies that model aspects of a mass-transit railway ticketing system. The first hierarchy was produced for an existing Object-Z specification of the system while the second was derived using FCA. Contrasting the two hierarchies revealed that they were essentially the same, however, the differences highlighted specification artefacts in the existing hierarchy. With respect to the design phase, the thesis discusses the use of FCA for the navigation and visualisation of Formal Specifications written in Z. In response to the continued call for formal methods tool support, we implement and explore a prototype specification browser that exploits the abstractions afforded by FCA. The research hypothesis is an integrated architecture for navigating formal specifications using FCA. This architecture is realised using ZML and ToscanaJ to produce a practical research tool. The thesis also includes the first broad survey of FCA in the domain of software engineering and an FCA-based methodology for surveying academic literature in general.

Currently, the bulk of applications of Formal Concept Analysis (FCA) in software engineering have focussed on software maintenance and re-engineering. In this thesis we broaden the approach by applying FCA to a number of early-phase activities within the software engineering life-cycle. With respect to the requirements engineering phase, a case study is presented comparing two class hierarchies that model aspects of a mass-transit railway ticketing system. The first hierarchy was produced for an existing Object-Z specification of the system while the second was derived using FCA. Contrasting the two hierarchies revealed that they were essentially the same, however, the differences highlighted specification artefacts in the existing hierarchy. With respect to the design phase, the thesis discusses the use of FCA for the navigation and visualisation of Formal Specifications written in Z. In response to the continued call for formal methods tool support, we implement and explore a prototype specification browser that exploits the abstractions afforded by FCA. The research hypothesis is an integrated architecture for navigating formal specifications using FCA. This architecture is realised using ZML and ToscanaJ to produce a practical research tool. The thesis also includes the first broad survey of FCA in the domain of software engineering and an FCA-based methodology for surveying academic literature in general.