Spontaneous current-layer fragmentation and cascading reconnection in solar flares: II. Relation to observations

In the paper by B\'arta et al. (arXive:astro-ph:/1011.4035, 2010) the authors addressed some open questions of the CSHKP scenario of solar flares by means of high-resolution MHD simulations. They focused, in particular, on the problem of energy transfer from large to small scales in decaying flare current sheet (CS). Their calculations suggest, that magnetic flux-ropes (plasmoids) are formed in full range of scales by a cascade of tearing and coalescence processes. Consequently, the initially thick current layer becomes highly fragmented. Thus, the tearing and coalescence cascade can cause an effective energy transfer across the scales. In the current paper we investigate whether this mechanism actually applies in solar flares. We extend the MHD simulation by deriving model-specific features that can be looked for in observations. The results of the underlying MHD model showed that the plasmoid cascade creates a specific hierarchical distribution of non-ideal/acceleration regions embedded in the CS. We therefore focus on the features associated with the fluxes of energetic particles, in particular on the structure and dynamics of emission regions in flare ribbons. We assume that the structure and dynamics of diffusion regions embedded in the CS imprint themselves into structure and dynamics of flare-ribbon kernels by means of magnetic-field mapping. Using the results of the underlying MHD simulation we derive the expected structure of ribbon emission and we extract selected statistical properties of the modelled bright kernels. Comparing the predicted emission and its properties with the observed ones we obtain a good agreement of the two.Comment: 7 pages, 5 figure

A Taxonomy of Hyperlink Hiding Techniques

Hidden links are designed solely for search engines rather than visitors. To get high search engine rankings, link hiding techniques are usually used for the profitability of black industries, such as illicit game servers, false medical services, illegal gambling, and less attractive high-profit industry, etc. This paper investigates hyperlink hiding techniques on the Web, and gives a detailed taxonomy. We believe the taxonomy can help develop appropriate countermeasures. Study on 5,583,451 Chinese sites' home pages indicate that link hidden techniques are very prevalent on the Web. We also tried to explore the attitude of Google towards link hiding spam by analyzing the PageRank values of relative links. The results show that more should be done to punish the hidden link spam.Comment: 12 pages, 2 figure

How the web continues to fail people with disabilities

The digital divide is most often understood as that between the IT haves and have-nots. However, if there is one minority group that can be, and often is excluded from the world wide web, even if they have a computer, it is disabled people. The Special Educational Needs and Disabilities Act 2001 (SENDA) extended the provisions within the Disability Discrimination Act 1995 regarding the provision of services to the education sector. Yet accessible web design, dependent on professional coding standards, adherence to guidelines, and user testing, remains rare on the web. This paper examines the background to professional coding standards, and adherence to guidelines, in an attempt to find out why the web continues to fail people with disabilities. It begins by examining the progress of the transition in the 1990s from old style HTML to strict XHTML. It applauds the vision behind that transition, charts its progress identifying the principle constituencies that it involves – and how well each has played its part. It then focuses on the further problem of the requirement for user testing to iron out anomalies not covered by standards and guidelines. It concludes that validating XHTML code is desirable, but that user testing also needs to be undertaken. It identifies the complex and heterogeneous network of interrelated concerns through which the needs of disabled web users remain unheeded. To support its argument, the paper details the results of two studies – 1) of the homepages of 778 public bodies and blue chip companies, which found only 8% of homepages validated against any declared Document Type Declarations (DTD), and 2) a wider research project on employment websites which also included disabled user testing and a number of focus groups and interviews with disabled users and web development companies

Text books untuk mata kuliah pemrograman web

.HTML.And.Web.Design.Tips.And.Techniques.Jan.2002.ISBN.0072228253.pd

An Empirical Study of CSS Code Smells in Web Frameworks

Cascading Style Sheets (CSS) has become essential to front-end web development for the specification of style. But despite its simple syntax and the theoretical advantages attained through the separation of style from content and behavior, CSS authoring today is regarded as a complex task. As a result, developers are increasingly turning to CSS preprocessor languages and web frameworks to aid in development. However, previous studies show that even highly popular websites which are known to be developed with web frameworks contain CSS code smells such as duplicated rules and hard-coded values. Such code smells have the potential to cause adverse effects on websites and complicate maintenance. It is therefore important to investigate whether web frameworks may be encouraging the introduction of CSS code smells into websites. In this thesis, we investigate the prevalence of CSS code smells in websites built with different web frameworks and attempt to recognize a pattern of CSS behavior in these frameworks. We collect a dataset of several hundred websites produced by each of 19 different frameworks, collect code smells and other metrics present in the CSS code of each website, train a classifier to predict which framework the website was built with, and perform various clustering tasks to gain insight into the correlations between code smells. Our results show that CSS code smells are highly prevalent in websites built with web frameworks, we achieve an accuracy of 39% in correctly classifying the frameworks based on CSS code smells and metrics, and we find interesting correlations between code smells

Integrable e-lements for Statistics Education

Without doubt modern education in statistics must involve practical, computer-based data analysis but the question arises whether and how computational elements should be integrated into the canon of methodological education. Should the student see and study high-level programming code right at the beginning of his or her studies? Which technology can be presented during class and which computational elements can re-occur (at increasing level of complexity) during the different courses? In this paper we address these questions and discuss where e-techniques have their limits in statistics education.electronic books, hypertext, e-supported teaching, statistical software