Ground Truth for Layout Analysis Performance Evaluation

Over the past two decades a significant number of layout analysis (page segmentation and region classification) approaches have been proposed in the literature. Each approach has been devised for and/or evaluated using (usually small) application-specific datasets. While the need for objective performance evaluation of layout analysis algorithms is evident, there does not exist a suitable dataset with ground truth that reflects the realities of everyday documents (widely varying layouts, complex entities, colour, noise etc.). The most significant impediment is the creation of accurate and flexible (in representation) ground truth, a task that is costly and must be carefully designed. This paper discusses the issues related to the design, representation and creation of ground truth in the context of a realistic dataset developed by the authors. The effectiveness of the ground truth discussed in this paper has been successfully shown in its use for two international page segmentation competitions (ICDAR2003 and ICDAR2005)

Surface quotients of hyperbolic buildings

Let I(p,v) be Bourdon's building, the unique simply-connected 2-complex such that all 2-cells are regular right-angled hyperbolic p-gons and the link at each vertex is the complete bipartite graph K(v,v). We investigate and mostly determine the set of triples (p,v,g) for which there exists a uniform lattice {\Gamma} in Aut(I(p,v)) such that {\Gamma}\I(p,v) is a compact orientable surface of genus g. Surprisingly, the existence of {\Gamma} depends upon the value of v. The remaining cases lead to open questions in tessellations of surfaces and in number theory. Our construction of {\Gamma}, together with a theorem of Haglund, implies that for p>=6, every uniform lattice in Aut(I) contains a surface subgroup. We use elementary group theory, combinatorics, algebraic topology, and number theory.Comment: 23 pages, 4 figures. Version 2 incorporates referee's suggestions including new Section 7 discussing relationships between our constructions, previous examples, and surface subgroups. To appear in Int. Math. Res. No

Constructing Quality Feedback to the Students in Distance Learning: Review of the Current Evidence with Reference to the Online Master Degree in Transplantation

Introduction: It was a challenge to design a feedback pathway for distance learning course that deals with complexand ambiguous clinical subject like organ transplantation. This course attracts mature clinicians (n=117 spread overthree modules) from 27 countries where in addition to the time and zone barriers; there are cultural, institutionalbackground and also ethnic barriers. In addition to the challenges faced in designing the curriculum and assessmentthat match this diverse group of students, we have to deliver a quality feedback to achieve our leaning objective. Howwould we construct and deliver this feedback to students you have not seen (in a virtual classroom) and may be on adifferent continent of this busy planet?Methods: We analysed the published data on feedback with reflection on the nature of this course and the pedagogyused while considering the diversity of the students joined this courseConclusion: In this distance-learning course constructing a quality feedback to the students is more technicallydemanding compared to a traditional course. Students in distance learning need much more support and feedback thanin a traditional course. There is a potential threat that these students feel isolated in their own online world and may notengage with this virtual educational environment properly.</jats:p

Implementation of Critical Threshold Concept in Clinical Transplantation: A New Horizon in Distance Learning

Background: While variations in medical practice are a norm and each patient poses a multitude of challenges, many clinicians are not comfortable in dealing with unexpected complex issues even though they may have enough knowledge as demonstrated by passing a number of tricky certifying (or exit) examinations. One reason for the lack of self-efficacy, even if being endowed with good knowledge, is that we are not good in learning from errors. A regular reflective practice offers superb learning opportunities when a clinician is “stuck in a mire”. Difficult clinical situations warrant a flexible and, at the same time, an evidence-based approach to ensure that crucial decision-making process is correct and efficient. Each clinical case offers a great opportunity to reinforce these “threshold concepts”, however, not everyone of us is “blessed” with these crucial not-so-difficult-to-acquire skills so necessary to be a life-long learner. The faculty of this course (a totally on-line MSc in Transplant Sciences) aims for unceasing engagement with students in order to facilitate them to negotiate through “stuck places” and “tricky bends” in their own work place. This course, not just meant for knowledge transfer, provides a platform that allows participants (the students and faculty) to learn from each other’s experience by using “e-blackboard”. The mainstay of this course are twofold: (a) Emphasis on achieving critical decision-making skills, (b) Regular feedback to allow reflective practice and, thereby, constantly learning from errors and reinforcing good practices. The aim of this article is to assess the performance of educators and how well the “ethos of critical threshold” has been accepted from the perspective of students. Methods: The critical thresholds of each chapter in 4 modules of this totally on-line course were defined to a razor-sharp precision. Learning objectives of learning activity were defined to achieve constructive alignment with critical threshold. We employed level 1, 2, 4 and 5 of Kirkpatrick pyramid, (a) for the evaluation of performance of educators of program, and (b) to evaluate the acceptance of this non-traditional format in clinical medicine education by postgraduate 80 students in 22 countries.Results: Students’ survey (Kirkpatrick level 1) was done only for module 1 of cohort 1 reported students’ satisfaction rate of 93%. Excluding a total of 12 drop-outs in 2 modules (n=10 in first cohort’s module 1, and n=2 in module 2), as many as 93% of students of first cohort passed module. Nine out of 60 registrants of module 1 in 2nd cohort took recess for one year requesting to join back as a part of 3rd cohort commencing one year later, all 51 who continued passed though 3 of them had to resit. All those who passed module 1 (both cohorts) and 2 (1st cohort) registered for their respective next module (return on investment Kirkpatrick level 5). Conclusion: For a successful model in distance learning in clinical transplantation it is imperative for the students to accomplish well defined “critical-decision making” skills. In order to learn critical thresholds, a regular feedback is integral to learning from reflective practice. This course equips the students to develop skills of negotiating “sticky mire”, as obvious from perceived high return of investment

Ramified rectilinear polygons: coordinatization by dendrons

Simple rectilinear polygons (i.e. rectilinear polygons without holes or cutpoints) can be regarded as finite rectangular cell complexes coordinatized by two finite dendrons. The intrinsic $l_1$-metric is thus inherited from the product of the two finite dendrons via an isometric embedding. The rectangular cell complexes that share this same embedding property are called ramified rectilinear polygons. The links of vertices in these cell complexes may be arbitrary bipartite graphs, in contrast to simple rectilinear polygons where the links of points are either 4-cycles or paths of length at most 3. Ramified rectilinear polygons are particular instances of rectangular complexes obtained from cube-free median graphs, or equivalently simply connected rectangular complexes with triangle-free links. The underlying graphs of finite ramified rectilinear polygons can be recognized among graphs in linear time by a Lexicographic Breadth-First-Search. Whereas the symmetry of a simple rectilinear polygon is very restricted (with automorphism group being a subgroup of the dihedral group $D_4$), ramified rectilinear polygons are universal: every finite group is the automorphism group of some ramified rectilinear polygon.Comment: 27 pages, 6 figure

Rebuffing Royals? Afrikaners and the royal visit to South Africa in 1947’

This article traces the responses of Afrikaners to the symbolism and political purposes of the 1947 royal visit to Southern Africa, the first post-war royal tour and the first visit of a reigning sovereign to the Union of South Africa. Taking place in the aftermath of a war that had caused bitter political divisions within Afrikaner ranks and stimulated radical populist nationalism, a royal tour intended to express the crown's gratitude for South Africa's participation in that war was bound to be contentious. Drawing on press accounts, biographies, autobiographies and archival sources, this article argues that the layered reactions of Afrikaners demonstrate that, even on the eve of the National Party's electoral victory on a republican and apartheid platform, attitudes towards monarchy and the British connection were more fluid and ambiguous than either contemporary propaganda or recent accounts have allowed. The diverse meanings attributed to this iconic royal tour reveal a process of intense contestation and reflection about South Africa's place in an empire that was in the throes of post-war redefinition and transformation, and confirm recent characterisations of the 1940s as one of manifold possibilities such that outcomes, like the electoral victory of the National Party in the following year, was far from pre-determined

The influence of multiple representations on the learning of calculus by ESL students

The goals of this study were to research the learning difficulties among a group of four pre-university introductory calculus students who were mainly international students studying English as a Second Language (M). The intention was to create a constructivist-style classroom environment in order to determine if it could improve students` knowledge about the use and management of multiple representations (that is, graphical, rum~ symbolic, pictorial, linguistic or diagrammatic approaches for problem representation), increase their classroom communication as a means to improving ability in the modelling of calculus word problems, and to develop, implement and evaluate a teaching package that encouraged the use of multiple representations as a means of improving conceptual understanding. The achievement of these goals was sought by means of the development, implementation and evaluation of a number of calculus extended tasks that encouraged the use of multiple representations. These activities facilitated the compilation of a menu of approaches to the solution of mathematical problems, while the longitudinal nature of the study allowed for the monitoring of student changes in their preferred approach. A traditional calculus curriculum was used for the study, but the instructional emphasis was based more on students' understanding of concepts in a classroom environment utilising a constructivist approach rather than on their memorising computational techniques. Reading, writing, and discussion were emphasised m small group settings to develop language skills and to foster an appreciation of the alternative solution strategies of individual students.The study was conducted at an International College north of Perth in Western Australia, and the majority of students in the sample were from Non-English-Speaking-Backgrounds (NESB). A range of methods was used to collect qualitative and quantitative data in order to increase the credibility of the research. These methods included audio recordings of structured task-based interviews with each of the four students in the sample; teacher analysis of student worksheets; my classroom observations; the analysis of alternative student conceptions on assessment tasks obtained through post-test interviews, and my personal reflections. Quality controls were employed to ensure the credibility of the data collected. As classroom teacher and principal researcher, it was possible for me to treat each of the four students involved as an individual case study. Descriptive questionnaires were used in order to gain information regarding the course and the use of graphics calculators. The results are applicable to ESL introductory calculus students only, and the nature of the sample implies a number of study limitations detailed in Chapter Five. There was extensive evidence of the benefits of the use of a multi-representational mode and evidence also of the benefits of encouraging the use of a diversity of modes of classroom instruction. Outcomes of the study were qualified by the difficulties ESL students face in coordinating conflicting information and interpreting the language demands of problem presentation. It is expected that this study will assist m extending the knowledge and understanding of the learning difficulties faced by ESL students in the am of pre-university calculus.Results of this study suggest that instructional material has an important influence on ESL students’ use and management of multiple representations. However, there are often limitations to the influence of the material due to student preferences, mathematical ability and firmly held beliefs as well as on the amount of detail presented in a problem Secondly, small group learning environments based on a constructivist approach were found to influence student ability to model calculus word problems in a positive manner, provided there is teacher support to overcome cognitive obstacles. Finally, it was established that an effective teaching package could be developed to assist ESL students in calculus learning. The teaching package's evaluation highlighted the need for matching language use in problem presentation with the current mathematical language register of each student