zoo is an R package providing an S3 class with methods for indexed totally ordered observations, such as irregular time series. Its key design goals are independence of a particular index/time/date class and consistency with base R and the "ts" class for regular time series. This paper describes how these are achieved within zoo and provides several illustrations of the available methods for "zoo" objects which include plotting, merging and binding, several mathematical operations, extracting and replacing data and index, coercion and NA handling. A subclass "zooreg" embeds regular time series into the "zoo" framework and thus bridges the gap between regular and irregular time series classes in R. / Series: Research Report Series / Department of Statistics and Mathematics

In this dissertation we solve several combinatorial problems in different areas of mathematics: automata theory, combinatorics of partially ordered sets and extremal combinatorics. Firstly, we focus on some new automata that do not seem to have occurred much in the literature, that of solvability of mazes. For our model, a maze is a countable strongly connected digraph together with a proper colouring of its edges (without two edges leaving a vertex getting the same colour) and two special vertices: the origin and the destination. A pointer or robot starts in the origin of a maze and moves naturally between its vertices, according to a sequence of specific instructions from the set of all colours; if the robot is at a vertex for which there is no out-edge of the colour indicated by the instruction, it remains at that vertex and proceeds to execute the next instruction in the sequence. We call such a finite or infinite sequence of instructions an algorithm. In particular, one of the most interesting and very natural sets of mazes occurs when our maze is the square lattice Z2 as a graph with some of its edges removed. Obviously, we need to require that the origin and the destination vertices are in the same connected component and it is very natural to take the four instructions to be the cardinal directions. In this set-up, we make progress towards a beautiful problem posed by Leader and Spink in 2011 which asks whether there is an algorithm which solves the set of all such mazes. Next, we address a problem regarding symmetric chain decompositions of posets. We ask if there exists a symmetric chain decomposition of a 2 × 2 × ... × 2 × n cuboid (k 2’s) such that no chain has a subchain of the form (a1,...,ak,0) ≺ ... ≺ (a1,...,ak,n−1)? We show this is true precisely when k≥5 and n≥3. Thisquestion arises naturally when considering products of symmetric chain decompositions which induce orthogonal chain decompositions — the existence of the decompositions provided in this chapter unexpectedly resolves the most difficult case of previous work by Spink on almost orthogonal symmetric chain decompositions (2017) which makes progress on a conjecture of Shearer and Kleitman. Moreover, we generalize our methods to other finite graded posets. Finally, we address two different problems in extremal combinatorics related to mathematical physics. Firstly, we study metastable states in the Ising model. We propose a general model for 1-flip spin systems, and initiate the study of extremal properties of their stable states. By translating local stability conditions into Sperner- type conditions, we provide non-trivial upper bounds which are often tight for large classes of such systems. The last topic we consider is a deterministic bootstrap percolation type problem. More specifically, we prove several extremal results about fast 2-neighbour percolation on the two dimensional grid.

Flagella, the helical propellers that extend from the bacterial cell surface, illustrate how complex nanomachines assemble outside the cell. The sequential construction of the flagellar rod, hook, and filament requires export of thousands of structural subunits across the cell membrane and this is achieved by a specialised flagellar Type III Secretion System (fT3SS) located at the base of each flagellum. The fT3SS imposes a crude ordering of subunits, with filament subunits only exported once the rod and hook are complete. This “export specificity switch” is controlled by the FlhB component of the fT3SS export gate in response to a signal from the exported molecular ruler FliK, which monitors the length of the growing hook. This study seeks to clarify how rod and hook subunits interact with FlhB, and how FlhB switches export specificity. Rod and hook subunits possess a conserved gate recognition motif (GRM; Fxxxφ, with φ being any hydrophobic residue) that is proposed to bind a surface-exposed hydrophobic patch on the FlhB cytosolic domain. Mutation of the GRM phenylalanine and the final hydrophobic residue resulted in impaired subunit export and decreased cell motility. Isothermal titration calorimetry was performed to assess whether subunit export order is imposed at FlhB. These experiments showed that rod and hook subunits bind to FlhB with micromolar dissociation constants (5-45 μM), suggesting transient interactions. There was no clear correlation between subunit affinity for FlhB and the order of subunit assembly in the nascent flagellum. Solution-state nuclear magnetic resonance (NMR) spectroscopy supported prior data showing that rod and hook subunits interact with FlhB’s surface-exposed hydrophobic patch. NMR also indicated that residues away from the patch undergo a conformational change on subunit binding. FlhB autocleaves rapidly in its cytosolic domain, and the resulting polypeptides (FlhBCN and FlhBCC) are held together by non-covalent interactions between b-strands that encompass the autocleavage site. The autocleavage event is a prerequisite for the export specificity switch, but its function is unclear. Analysis of the cellular localization of FlhBCN and FlhBCC revealed that FlhBCC dissociated from the membrane export machinery, but only in the presence of FliK. Biochemical and biophysical studies of FlhB variants that undergo export specificity switching in the absence of FliK showed that these FlhB “autonomous switchers” were less stable than wildtype FlhB and their FlhBCC domain could dissociate from the export machinery in the absence of FliK. The results suggest that the export specificity switch involves a FliK-dependent loss of FlhBCC from the export machinery, eliminating the binding site for rod and hook subunits.

Promover a segurança viária no entorno escolar é uma estratégia que contribui para que sejam construídas cidades seguras, saudáveis e sustentáveis. Nesse sentido, este estudo é dedicado a identificar a influência das características da estrutura urbana na frequência e na severidade dos acidentes no entorno de escolas de educação básica de Porto Alegre. A análise da frequência e da severidade de acidentes foi conduzida através da estimação de modelos econométricos: binomial negativo e logit ordenado, respectivamente. Para esses, foram calculados os efeitos marginais, permitindo a observação da magnitude dos impactos das variáveis explicativas sobre as variáveis dependentes. As variáveis dependentes frequência e severidade foram extraídas dos acidentes registrados em Porto Alegre entre 2012 e 2014. Foram incluídas, simultaneamente, variáveis da estrutura urbana, das escolas, socioeconômicas e dos acidentes (para a severidade). A partir do geoprocessamento dos dados existentes, os entornos escolares puderam ser caracterizados para três diferentes áreas circulares de análise (buffer ring) de raios de 100, 150 e 200 metros, permitindo a comparação do uso das diferentes áreas. O conjunto de estimativas indica que áreas menores produzem modelos de melhor desempenho para ambas as técnicas empregadas. No entanto, áreas maiores permitem a análise de maior quantidade de variáveis relativas à estrutura urbana. Essa relação sugere os benefícios da escolha a partir do trade-off entre ajuste do modelo e sua capacidade de propiciar análises de variáveis. Foi identificado que a frequência e a severidade de acidentes podem estar relacionadas a uma única variável explicativa de formas opostas – a partir de sinais contrários. Essa diferença de resultados para frequência e severidade de acidentes indica que há maiores benefícios em analisá-las em conjunto. Identificou-se ainda que existem benefícios para a segurança viária em áreas de estrutura urbana com quarteirões menores e maior quantidade de interseções de quatro vias, em frequência e severidade, respectivamente. Já as áreas mais arborizadas tendem a apresentar acidentes de menor severidade nos casos de usuários de modos ativos. / Fostering road safety nearby schools is a strategy that contributes to build safe, healthy and sustainable cities. The aim of this study is to identify the influence of the built environment characteristics in the frequency and severity of accidents nearby elementary and secondary schools in Porto Alegre. The frequency and severity of the accidents were analyzed using econometric models: negative binomial and ordered logit, respectively. The evaluation of their marginal effects allowed the magnitude of the impact caused by the explanatory variable on the dependent variables to be observed. The measured variables frequency and severity were extracted from accidents registered in Porto Alegre from 2012 and 2014. Built environment, socioeconomic and school variables were also included, as well as accident data (for severity). Data geoprocessing allowed school surroundings to be characterized for three different buffer rings, measuring 100, 150 and 200 meters of radius. Thereby it was possible to compare the inclusion of different areas in the study. The estimations indicates that models based on smaller areas have better performances for both employed techniques, whereas larger areas allow the study of a bigger quantity of urban infrastructure variables. That indicates the benefits of choosing based on a trade-off between model adjustment and capacity to engender the analysis of variables. It was shown that frequency and severity of accidents could be related to a single explanatory variable in opposite ways – based on contrary signs. This difference in the results found for frequency and severity indicates that there are more benefits when analyzing them together. Moreover, there are benefits for road safety in areas where the city blocks are shorter and where there are more four-way intersections, in frequency and severity of accidents, respectively. Also, areas of more important afforestation tend to decrease the severity of accidents involving users of active modes.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Este trabalho tem como objetivo mostrar que o conjunto dos nÃmeros reais à um corpo ordenado completo e que, a menos de um isomorfismo, à Ãnico. Este trabalho à voltado para todos aqueles que tenham interesse em MatemÃtica, sobretudo, para os professores de MatemÃtica do ensino mÃdio que utilizam as propriedades do conjunto dos nÃmeros reais sem conhecer a teoria matemÃtica envolvida. Para tanto, à necessÃrio caracterizar o conjunto dos reais a fim de provar suas propriedades. Aqui, utilizamos duas construÃÃes, a saber: os reais via sequÃncias de Cauchy devido a Cantor e os reais via Cortes de Dedekind. A partir dessas caracterizaÃÃes, conseguimos construir um corpo K munido das operaÃÃes de soma e multiplicaÃÃo onde mostramos que ele cumpre as condiÃÃes da definiÃÃo de corpo. Definida uma relaÃÃo de ordem em K, mostramos que tal corpo à ordenado e, alÃm disso, conseguimos mostrar que todo subconjunto de K admite supremo, o que quer dizer que tal corpo à completo. Finalmente, mostramos que qualquer outro corpo ordenado completo que possa, por ventura, existir à uma mera caracterizaÃÃo de ℝ, o que quer dizer que ℝ à Ãnico, a menos dessas possÃveis outras caracterizaÃÃes. Tal caracterizaÃÃo serà chamada de isomorfismo que à uma funÃÃo bijetora de ℝ para K. / This work aims to show that the set of real numbers is a complete ordered field that, within an isomorphism, is unique. This work is aimed at all those who are interested in mathematics, especially for that high school math teacher who uses the real numbers of the set of properties without knowing the mathematical theory involved. Therefore, it is necessary to characterize the set of the real in order to prove their properties. Here, we use two buildings, namely: the real via Cauchy sequences due to Cantor and the real via Dedekind cuts. From these characterizations, we can build a field K equipped with the addition and multiplication operations which show that it meets the definition of field conditions. Set an order relation in K, we show that such a body is ordered and in addition, we show that every subset of K admits supreme, which means that such a field is complete. Finally, we show that any complete ordered field that can, perchance appear is a mere characterization of ℝ, which means that ℝ is unique, unless these possible other characterizations. This characterization will be called isomorphism which is a function bijetora of ℝ to K.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-08-28T17:49:12Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Numeros Reais Um Corpo Ordenado Completo.pdf: 4328358 bytes, checksum: 5062827ca2822fd04229310850171740 (MD5) / Made available in DSpace on 2014-08-28T17:49:12Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Numeros Reais Um Corpo Ordenado Completo.pdf: 4328358 bytes, checksum: 5062827ca2822fd04229310850171740 (MD5) Previous issue date: 2013-03-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This paper aims to expand knowledge about the real numbers, providing a new perspective on their conceptual construction. Initially, covers up some historical facts that were of utmost importance in the process of conceptual evolution of the real numbers. Secondly, through the development of theories of abstract algebra, sets and mathematical analysis, is used a axiomatic method to expose the complete ordered field of real, stating and proving some of its properties. Finally, we discuss some relevant aspects of the correspondence between the real field and line, and also the correspondence between the real field and decimals. / Este trabalho tem como objetivo ampliar os conhecimentos sobre os números reais, proporcionando uma nova perspectiva sobre sua construção conceitual. Inicialmente, aborda-se alguns fatos históricos que foram de maior importância no processo da evolução conceitual dos números reais. Posteriormente, por meio do desenvolvimento das teorias de álgebra, de conjuntos e de análise matemática, utiliza-se de um método axiomático para expor uma construção do corpo ordenado e completo dos reais, enunciando e provando algumas de suas propriedades. Finalmente, abordam-se alguns aspectos relevantes da correspondência entre o corpo dos reais e a reta, e ainda da correspondência entre o corpo dos reais e os decimais.

Work zone tends to cause hazardous conditions for drivers and construction workers since work zones generate conflicts between construction activities and the traffic, therefore aggravate the existing traffic conditions and result in severe traffic safety and operational problems. To address the influence of various factors on the crash severity is beneficial to understand the characteristics of work zone crashes. The understanding can be used to select proper countermeasures for reducing the crash severity at work zones and improving work zone safety. In this dissertation, crash severity models were developed to explore the factor impacts on crash severity for two work zone crash datasets (overall crashes and rear-end crashes). Partial proportional odds logistic regression, which has less restriction to the parallel regression assumption and provides more reasonable interpretations of the coefficients, was used to estimate the models. The factor impacts were summarized to indicate which factors are more likely to increase work zone crash severity or which factors tends to reduce the severity. Because the speed variety is an important factor causing accidents at work zone area, the work zone speed profile was analyzed and modeled to predict the distribution of speed along the distance to the starting point of lane closures. A new learning machine algorithm, support vector regression (SVR), was utilized to develop the speed profile model for freeway work zone sections under various scenarios since its excellent generalization ability. A simulation-based experiment was designed for producing the speed data (output data) and scenario data (input data). Based on these data, the speed profile model was trained and validated. The speed profile model can be used as a reference for designing appropriate traffic control countermeasures to improve the work zone safety.

This work presents new models and algorithms for creating, modifying, and controlling access to complex text. The digitization of texts opens new opportunities for preservation, access, and analysis, but at the same time raises questions regarding how to represent and collaboratively edit such texts. Two issues of particular interest are modelling the relationships of markup (annotations) in complex texts, and controlling the creation and modification of those texts. This work addresses and connects these issues, with emphasis on data modelling, algorithms, and computational complexity; and contributes new results in these areas of research. Although hierarchical models of text and markup are common, complex texts often exhibit layers of overlapping structure that are best described by multihierarchical markup. We develop a new model of multihierarchical markup, the globally ordered GODDAG, that combines features of both graph- and range-based models of markup, allowing documents to be unambiguously serialized. We describe extensions to the XPath query language to support globally ordered GODDAGs, provide semantics for a set of update operations on this structure, and provide algorithms for converting between two different representations of the globally ordered GODDAG. Managing the collaborative editing of documents can require restricting the types of changes different editors may make, while not altogether restricting their access to the document. Fine-grained access control allows precisely these kinds of restrictions on the operations that a user is or is not permitted to perform on a document. We describe a rule-based model of fine-grained access control for updates of hierarchical documents, and in this context analyze the document generation problem: determining whether a document could have been created without violating a particular access control policy. We show that this problem is undecidable in the general case and provide computational complexity bounds for a number of restricted variants of the problem. Finally, we extend our fine-grained access control model from hierarchical to multihierarchical documents. We provide semantics for fine-grained access control policies that control splice-in, splice-out, and rename operations on globally ordered GODDAGs, and show that the multihierarchical version of the document generation problem remains undecidable.

In USA, despite recent efforts to improve work zone safety, the number of crashes and fatalities at work zones has increased continuously over several past years. For addressing the existing safety problems, a clear understanding of the characteristics of work zone crashes is necessary. This thesis summarized a research study focusing on work zone traffic crash analysis to investigate the characteristics of work zone crashes and to identify the factors contributing to injury severity at work zones. These factors included roadway design, environmental conditions, traffic conditions and vehicle/driver features. Especially, special population groups, which divided into older, middle Age, and young, were inspected. This study was based on history crash data from the Florida State, which were extracted from the Florida CAR (Crash Analysis Reporting) system. Descriptive statistics method was used to find the characteristics of crashes at work zones. After then, an injury severity predict model, using the ordered probit regression technology, was developed to investigate the impacts of various factors on different the injury severity at work zones. From the model, it can be concluded that some factors, including the road section with curve, alcohol/drugs involved, a high speed, angle crash and too young or old drivers are more likely to increase the probability of angle crashes. Based on the magnitudes of the variable coefficients, the factor of maximum posted speed have a great impact to injury severity, which shows restriction to driving speed is principle countermeasure for improving work zone safety.

中國在改革開放後，挾廉價勞工、充沛資源及廣大市場並與台灣同文同種的優勢，使許多台商西進投資，如今大陸已成為台灣對外投資的首選區域；而台灣對大陸貿易即使在沒有三通情況下，經由間接貿易對大陸進出口，也占台灣對外貿易主要地位。面對兩岸經貿深化情況，國人憂心會對國內經濟帶來負面效果，產生「產業外移大陸，負債徒留台灣」與「產業空洞化」的疑慮。 基於上述動機，本文透過海外直接投資相關理論，配合產業空洞化之相關指標來建立預期方向，利用經濟部對2006年所編製「製造業對外投資實況調查」之原始問卷資料，並採用 Ordered Probit模型，對於台灣製造業廠商特性、對外投資動機、對外投資地區及廠商產業別，進行廠商國內生產規模與就業人數決定因素之分析。研究發現廠商對中國等非新進國家投資可能產生減少國內投資擴廠及雇用人才的負面效果，但透過下列廠商特性與投資型態將可抵銷負面效果，並降低空洞化之產生。 (一) 對外投資地區：選擇到先進國家投資的台商，較選擇投資在非先進國家的廠商而言，更能夠擴大國內生產規模及提高國內人才雇用。 (二) 廠商特性：台商事業如果獲利與降低國外投資率將傾向於擴張國內生產規模與提高國內就業人數；台商對外投資若生產方式若以水平整合，則傾向於提高國內就業量，卻不傾向於擴大國內生產規模。 (三) 廠商對外投資動機：當廠商對外投資動機為「擴張市場」時，傾向擴大國內生產規模；但對於提高國內人才雇用卻不顯著。當廠商對外投資動機為「節省成本」時，將不傾向於提高國內人才雇用。 (四) 研發總額比：台商國內事業研發金額占國內外研發總額比率越高，越傾向擴大國內生產規模與提高國內就業人數。