Helsinki Institute for Information Technology

About: Helsinki Institute for Information Technology is a facility organization based out in Espoo, Finland. It is known for research contribution in the topics: Population & Bayesian network. The organization has 630 authors who have published 1962 publications receiving 63426 citations.

Synthesizing small and reliable tile sets for patterned DNA self-assembly

Abstract: We consider the problem of finding, for a given 2D pattern of colored tiles, a minimal set of tile types self-assembling to this pattern in the abstract Tile Assembly Model of Winfree (1998). This Patterned self-Assembly Tile set Synthesis (PATS) problem was first introduced by Ma and Lombardi (2008), and subsequently studied by Goos and Orponen (2011), who presented an exhaustive partition-search branch-and-bound algorithm (briefly PS-BB) for it. However, finding the true minimal tile sets is very time consuming, and PS-BB is not well-suited for finding small but not necessarily minimal solutions. In this paper, we modify the basic partition-search framework by using a heuristic to optimize the order in which the algorithm traverses its search space. We find that by running several parallel instances of the modified algorithm PS-H, the search time for small tile sets can be shortened considerably. We also introduce a method for computing the reliability of a tile set, i.e. the probability of its error-free self-assembly to the target tiling, based on Winfree's analysis of the kinetic Tile Assembly Model (1998). We present data on the reliability of tile sets found by the algorithms and find that also here PS-H constitutes a significant improvement over PS-BB.

Use of Social Navigation Features in Collaborative E-Learning

Abstract: EDUCO is a system for collaborative learning that uses real-time direct social navigation. Social navigation means making the navigation of other users visible to everyone else in the system. The paper discusses the social navigation features of EDUCO and reports empirical results regarding the collaborative behaviour of the students in a university-level Web-course. Contrary to our research hypothesis and the common wisdom in the research area, the data gathered showed that making other users’ navigation visible did not have an effect on navigation in this experiment.

A Hybrid Model of Context-aware Service Provisioning Implemented on Smart Phones

Abstract: Mobile users of future ubiquitous environments require novel means for locating relevant services available in their daily surroundings, where relevance has a user-specific definition. In this paper, we propose the hybrid service provisioning model which complements the traditional model of interaction service provider to consumer with peer-to-peer functionalities. In addition to being notified proactively and in a context-aware manner about services available in the surroundings, users can generate several types of contextual messages, attach them to services or to the environment, and share them with other peers. We have designed and implemented a platform that supports this hybrid service provisioning model. The current application prototype runs on commercial smart phones. To demonstrate the feasibility and technical deployability of our approach, we conducted field trials in which the research subject was a community of recreational boaters

LCP Array Construction in External Memory

Abstract: One of the most important data structures for string processing, the suffix array, needs to be augmented with the longest-common-prefix (LCP) array in numerous applications. We describe the first external memory algorithm for constructing the LCP array given the suffix array as input. The only previous way to compute the LCP array for data that is bigger than the RAM is to use a suffix array construction algorithm with complex modifications to produce the LCP array as a by-product. Compared to the best prior method, our algorithm needs much less disk space (by more than a factor of three) and is significantly faster. Furthermore, our algorithm can be combined with any suffix array construction algorithm including a better one developed in the future.

Opening the digital box for design work: supporting performative interactions, using inspirational materials and configuring of place

Abstract: We started the work reported on here with the ambition to create inspirational learning environments for design and architecture students in the spirit of Weiser’s vision of taking the computer “out of the box” and making computational resources augment a design studio environment ubiquitously Computing environments are becoming populated by a rich and diverse set of devices and networks, many of them integrated with the physical landscape of space and artefacts Early attempts to take the desktop metaphor of graphical interface design back to the real desktops and whiteboards by exploring new semantics of interaction was pioneered by Weiser’s group, as well as by Buxton and others (Weiser 1993; Fitzmaurice 1995; Rekimoto 1997) The idea to have a new and more complex set of physical handles to digital media promised a richer interaction between people and technology, and, in line with Engelbart’s pioneering work on direct manipulation for graphical user interfaces (Engelbart 1962), a new set of generic interface building blocks would open up a new realm for design of interaction technologies