Umut Topkara

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With an ever-increasing amount of available data on protein-protein interaction (PPI) networks and research revealing that these networks evolve at a modular level, discovery of conserved patterns in these networks becomes an important problem. Although available data on protein-protein interactions is currently limited, recently developed algorithms have(More)
Compared to other media, natural language text presents unique challenges for information hiding. These challenges require the design of a robust algorithm that can work under following constraints: (i) low embedding bandwidth, i.e., number of sentences is comparable with message length, (ii) not all transformations can be applied to a given sentence (iii)(More)
Information-hiding in natural language text has mainly consisted of carrying out approximately meaning-preserving modifications on the given cover text until it encodes the intended mark. A major technique for doing so has been synonym-substitution. In these previous schemes, synonym substitutions were done until the text "confessed", i.e., carried the(More)
A substantial portion of the text available online is of a kind that tends to contain many typos and ungrammatical abbreviations, e.g., emails, blogs, forums. It is therefore not surprising that, in such texts, one can carry out information-hiding by the judicious injection of typos (broadly construed to include abbreviations and acronyms). What is(More)
Two main results in the area of information hiding in natural language text are presented. A semantically-based scheme dramatically improves the information-hiding capacity of any text through two techniques: (i) modifying the granularity of meaning of individual sentences, whereas our own previous scheme kept the granularity fixed, and (ii) halving the(More)
Text-password based authentication schemes are a popular means of authenticating users in computer systems. Standard security practices that were intended to make passwords more difficult to crack, such as requiring users to have passwords that "look random" (high entropy), have made password systems less usable and paradoxically, less secure. In this work,(More)
MOTIVATION Co-evolution is a powerful mechanism for understanding protein function. Prior work in this area has shown that co-evolving proteins are more likely to share the same function than those that do not because of functional constraints. Many of the efforts founded on this observation, however, are at the level of entire sequences, implicitly(More)
Research on password authentication systems has repeatedly shown that people choose weak passwords because of the difficulty of remembering random passwords. Moreover, users with multiple passwords for unrelated activities tend to choose almost similar passwords for all of them. Many password schemes have been proposed to alleviate this problem, but they(More)
Timely access to the most up to date versions of resources, such as data and software, is of paramount importance for researchers in an active field like Biology. We introduce a grid enabled biological data and software collection portal architecture, SALSA (a Scalable Simple Architecture), that is tailored towards fast integration of new computational(More)