An Electronic topological picturebook

Ankara : The Department of Computer Engineering and Information Science and the Institute of Graduate Studies of Bilkent University, 1992.Thesis (Ph.D.) -- Bilkent University, 1992.Includes bibliographical references leaves 73-78.An electronic topological picturebook is envisaged as a computerized version of A Topological Picturehook by George K. Francis, .Springer-Verlag, New York (1987). Francis’ book is full of complicated topological figures, mostly drawn manually. The main goal of the thesis is to automate the production of such illustrations and to obtain publication-quality hardcopy using assorted techniques of computer graphics. To that end, sweeping is discussed as a major surface modeling tool. Some interactive methods are given to produce interesting topological surfaces. The program Tb (which stands for ‘Topologybook’) is described and various pictures generated by this software are presented. Tl· is a free-form surface modeler and produces topological shapes with little effort. Central to the implementation of Tb is a paradigm of solid modeling in which computation of a shape is regarded as sweeping with some parametric variations, viz. shape = sweep + control.Arslan, AhmetPh.D

Sweeping with all graphical ingredients in a topological picturebook

Sweeping is a powerful method to generate 3-D shapes in geometric modeling. In this paper we formulate a general matrix to give a mathematical definition of twisted-profiled sweep objects as a discrete approximation. While conceptually simple, our result is, to our best knowledge, the first precise formulation of sweeping with all graphical ingredients, viz. twisting, scaling, rotation, and translation. Twisted-profiled sweeping surfaces defined by contour, profile, trajectory, and guide curves are thus represented in concatenated matrix formulation. In addition, we give interactive methods to generate sweep objects and present sample figures produced within the framework of our implementation Tb, a topological picturebook. © 1992

On the correct determination of rotational angles for twisted-profiled sweep objects

In the context of the paper of V. Akman and A. Arslan, "Sweeping with All Graphical Ingredients in a Topological Picturebook" [Computers & Graphics, Vol. 16(3), pp. 273-281, 1992], a new construction of the rotational matrix is presented. This fixes a bug discovered by the first author. © 1994

Toward an Empirical Theory of Pulsar Emission. IX. On the Peculiar Properties and Geometric Regularity of Lyne & Manchester's "Partial Cone" Pulsars

Lyne & Manchester (1988) identified a group of some 50 pulsars they called "partial cones" which they found difficult to classify and interpret. They were notable for their asymmetric average profiles and asymmetric polarization position-angle (PPA) traverses, wherein the steepest gradient (SG) point fell toward one edge of the total intensity profile. Over the last two decades, this population of pulsars has raised cautions regarding the core/cone model of the radio pulsar-emission beam which implies a high degree of order, symmetry and geometric regularity. In this paper we reinvestigate this population "partial cone" pulsars on the basis of new single pulse polarimetric observations of 39 of them, observed with the Giant Meterwave Radio Telescope in India and the Arecibo Observatory in Puerto Rico. These highly sensitive observations help us to establish that most of these "partial cones" exhibit a core/cone structure just as did the "normal" pulsars studied in the earlier papers of this series. In short, we find that many of these "partial cones" are partial in the sense that the emission above different areas of their polar caps can be (highly) asymmetric. However, when studied closely we find that their emission geometries are overall identical to core/double cone structure encountered earlier-that is, with specific conal dimensions scaling as the polar cap size.Comment: Accepted for publication in ApJ, 42 pages with 45 figures, notes to table 2 and 3 are in the beginning of the appendix sectio

BOOKS & VOICES A Guest Artist Lecture Talk by Becky Beasley

Our Invited guest Artist from the UK Becky Beasley will explore her reading practices and spatial imagination in the context of her circular and revolutionary approach to learning from others’ perspectives and voices. The slide lecture will cover the background to her unique reading of, amongst others, William Faulkner and Thomas Bernard’s literary voices. She will also speak about her new-found understanding of how all this is an expression of her autistic point of view. PUBLICS and LUGEMIK are inviting you to join the Festival of Books and Voices. Initiated by PUBLICS and Lugemik, the Festival spreads out through the months of September, October and November, bringing together themes of Publishing and Voice. For this Autumn, our space in Vallila is showcasing an exhibition of 100 books published by Lugemik, an independent publishing initiative based in Tallinn. In celebration of the show, we will have a monthly program consisting of book launches, vinyl sound lounge, lectures, screenings, pop-up bookstores, discussions and readings! Festival of Books and Voices brings together book-related practices and the presence of voice – the two strands of PUBLICS that have been visible and active throughout the years, evolving through our public events and Library program. The festival continues the tradition of bringing attention to books and emphasising the context of our Library – a crucial and ever growing part of PUBLICS identity. At the beginning of each month, a scheduled event program will be announced

Reflexive Space. A Constructionist Model of the Russian Reflexive Marker

This study examines the structure of the Russian Reflexive Marker ( ся/-сь) and offers a usage-based model building on Construction Grammar and a probabilistic view of linguistic structure. Traditionally, reflexive verbs are accounted for relative to non-reflexive verbs. These accounts assume that linguistic structures emerge as pairs. Furthermore, these accounts assume directionality where the semantics and structure of a reflexive verb can be derived from the non-reflexive verb. However, this directionality does not necessarily hold diachronically. Additionally, the semantics and the patterns associated with a particular reflexive verb are not always shared with the non-reflexive verb. Thus, a model is proposed that can accommodate the traditional pairs as well as for the possible deviations without postulating different systems. A random sample of 2000 instances marked with the Reflexive Marker was extracted from the Russian National Corpus and the sample used in this study contains 819 unique reflexive verbs. This study moves away from the traditional pair account and introduces the concept of Neighbor Verb. A neighbor verb exists for a reflexive verb if they share the same phonological form excluding the Reflexive Marker. It is claimed here that the Reflexive Marker constitutes a system in Russian and the relation between the reflexive and neighbor verbs constitutes a cross-paradigmatic relation. Furthermore, the relation between the reflexive and the neighbor verb is argued to be of symbolic connectivity rather than directionality. Effectively, the relation holding between particular instantiations can vary. The theoretical basis of the present study builds on this assumption. Several new variables are examined in order to systematically model variability of this symbolic connectivity, specifically the degree and strength of connectivity between items. In usage-based models, the lexicon does not constitute an unstructured list of items. Instead, items are assumed to be interconnected in a network. This interconnectedness is defined as Neighborhood in this study. Additionally, each verb carves its own niche within the Neighborhood and this interconnectedness is modeled through rhyme verbs constituting the degree of connectivity of a particular verb in the lexicon. The second component of the degree of connectivity concerns the status of a particular verb relative to its rhyme verbs. The connectivity within the neighborhood of a particular verb varies and this variability is quantified by using the Levenshtein distance. The second property of the lexical network is the strength of connectivity between items. Frequency of use has been one of the primary variables in functional linguistics used to probe this. In addition, a new variable called Constructional Entropy is introduced in this study building on information theory. It is a quantification of the amount of information carried by a particular reflexive verb in one or more argument constructions. The results of the lexical connectivity indicate that the reflexive verbs have statistically greater neighborhood distances than the neighbor verbs. This distributional property can be used to motivate the traditional observation that the reflexive verbs tend to have idiosyncratic properties. A set of argument constructions, generalizations over usage patterns, are proposed for the reflexive verbs in this study. In addition to the variables associated with the lexical connectivity, a number of variables proposed in the literature are explored and used as predictors in the model. The second part of this study introduces the use of a machine learning algorithm called Random Forests. The performance of the model indicates that it is capable, up to a degree, of disambiguating the proposed argument construction types of the Russian Reflexive Marker. Additionally, a global ranking of the predictors used in the model is offered. Finally, most construction grammars assume that argument construction form a network structure. A new method is proposed that establishes generalization over the argument constructions referred to as Linking Construction. In sum, this study explores the structural properties of the Russian Reflexive Marker and a new model is set forth that can accommodate both the traditional pairs and potential deviations from it in a principled manner.Siirretty Doriast

The Prefix PO- and Aspect in Russian and Polish: A Cognitive Grammar Account

This study examines the meanings of the prefix po- and verbal aspect in Russian and Polish in a Cognitive Grammar framework. The principles of Cognitive Grammar adopted in this study are based on Langacker (1991). This study follows Dickey's (2000) East-West division of aspect, within which the prototypical meanings of the Russian perfective and imperfective aspects are temporal definiteness and qualitative temporal indefiniteness, respectively, and the prototypical meanings of the Polish perfective and imperfective aspects are temporal definiteness/totality and quantitative temporal indefiniteness. According to Cognitive Grammar, the prototype is the most salient node in a network; this study is based around an analysis of the meaning and grammatical function of the Russian delimitative in po- and the Polish distributive in po- as prototypes in their respective semantic networks for po-. Regarding the methodological approach of this dissertation, in addition to relying on the views presented in the traditional literature, quantitative data is also presented, consisting of dictionary counts and hit counts and relative frequencies drawn from online corpora in support of the view that the delimitative is the prototype verb in po- in Russian and the distributive is the prototype verb in po- in Polish. The results of the corpus-based research show that the productivity and level of use are higher for the prototype Russian delimitative in po- relative to the Polish delimitative in po-and for the prototype Polish distributive in po- relative to the Russian distributive in po-. The main conclusion arrived upon in this study is that the meanings of the prototype verb in po- and the prototypical perfective meaning in each language overlap, which is manifested as the ability of the prototype verb in po- to function as a perfective partner in the grammar

A Multi-Code Analysis Toolkit for Astrophysical Simulation Data

The analysis of complex multiphysics astrophysical simulations presents a unique and rapidly growing set of challenges: reproducibility, parallelization, and vast increases in data size and complexity chief among them. In order to meet these challenges, and in order to open up new avenues for collaboration between users of multiple simulation platforms, we present yt (available at http://yt.enzotools.org/), an open source, community-developed astrophysical analysis and visualization toolkit. Analysis and visualization with yt are oriented around physically relevant quantities rather than quantities native to astrophysical simulation codes. While originally designed for handling Enzo's structure adaptive mesh refinement (AMR) data, yt has been extended to work with several different simulation methods and simulation codes including Orion, RAMSES, and FLASH. We report on its methods for reading, handling, and visualizing data, including projections, multivariate volume rendering, multi-dimensional histograms, halo finding, light cone generation and topologically-connected isocontour identification. Furthermore, we discuss the underlying algorithms yt uses for processing and visualizing data, and its mechanisms for parallelization of analysis tasks.Comment: 18 pages, 6 figures, emulateapj format. Resubmitted to Astrophysical Journal Supplement Series with revisions from referee. yt can be found at http://yt.enzotools.org