Human activities contribute to the contamination of rivers by toxic elements, causing serious effects on health traditional communities in Amazon region. With aim verifying spatial distribution Hg and As concentrations a region affected gold mining Baú, Curuá, Curuaés River basin, municipality Altamira-PA, Brazilian Amazon, study was carried out using geostatistical maps. The quantification ele...

Traditional ranking models used in Web search engines rely on a static snapshot of the Web graph, basically the link structure of the Web documents. However, visitors’ browsing activities indicate the importance of a document. In the traditional static models, the information on document importance conveyed by interactive browsing is neglected. The nowadays Web server/surfer model lacks the abi...

Websites usually appear to the web surfer like isolated islands: Their self-description and their hyperlinks linking to other sites reflect solely the requirements, opinion and preferences of the respective site owner, there is no explicit relation to the information, service and product offers of competing sites, and the assessment of the site by other users is unknown as well. In contrast to ...

In this paper, we first extend the celebrated PageRank modification to a higher-order Markov chain. Although this system has attractive theoretical properties, it is computationally intractable for many interesting problems. We next study a computationally tractable approximation to the higher-order PageRank vector that involves a system of polynomial equations called multilinear PageRank. This...

Intrusions are often viewed as catastrophic events which destroy systems, wreak havoc on data through corruption or substitution, yield access to closely guarded sensitive information, or provide a springboard for hackers to attack other systems. Yet not all intrusions on the Web are the blatant, smash-and-grab, trash-the-site kind of attacks. Many attacks are more subtle, and some involve what...

The increasing number of uncharacterized protein structures necessitates the development of computational approaches for function annotation using the protein tertiary structures. Protein structure database search is the basis of any structure-based functional elucidation of proteins. 3D-SURFER is a web platform for real-time protein surface comparison of a given protein structure against the e...

Early approaches to mathematically abstracting websurfing behavior were largely based on first-order Markov models. Most humans however do not surf in a “memoryless” fashion, rather they are guided by their timedependent situational context and associated information needs. This belief is corroborated by the non-exponential revisit times observed in many site-centric weblogs. In this paper, we ...

Search engines use several criteria to rank webpages and choose which pages to display when answering a request. Those criteria can be separated into two notion, relevance and popularity. This notion of popularity is calculated by the search engine and is related to links made to the webpage. Malicious webmasters want to artificially increase their popularity, the techniques they use are often ...