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.

Improving Controllability and Predictability of Interactive Recommendation Interfaces for Exploratory Search

Abstract: In exploratory search, when a user directs a search engine using uncertain relevance feedback, usability problems regarding controllability and predictability may arise. One problem is that the user is often modelled as a passive source of relevance information, instead of an active entity trying to steer the system based on evolving information needs. This may cause the user to feel that the response of the system is inconsistent with her steering. Another problem arises due to the sheer size and complexity of the information space, and hence of the system, as it may be difficult for the user to anticipate the consequences of her actions in this complex environment. These problems can be mitigated by interpreting the user's actions as setting a goal for an optimization problem regarding the system state, instead of passive relevance feedback, and by allowing the user to see the predicted effects of an action before committing to it. In this paper, we present an implementation of these improvements in a visual user-controllable search interface. A user study involving exploratory search for scientific literature gives some indication on improvements in task performance, usability, perceived usefulness and user acceptance.

Securing the control channel of software-defined mobile networks

Abstract: Software-Defined Mobile Networks (SDMNs) are becoming popular as the next generation of telecommunication networks due to the enhanced performance, flexibility and scalability. In this paper, we study the new security challenges of the control channel of SDMNs and propose a novel secure control channel architecture based on Host Identity Protocol (HIP). IPsec tunneling and security gateways are widely used in today's mobile networks. The proposed architecture utilized these technologies to protect the control channel of SDMNs. We implement the proposed architecture in a testbed and analyze the security features. Moreover, we measure the performance penalty of security of proposed architecture and analyze its ability to protect the control channel from various IP (Internet Protocol) based attacks.

Multi-view kernel completion

Abstract: In this paper, we introduce the first method that (1) can complete kernel matrices with completely missing rows and columns as opposed to individual missing kernel values, with help of information from other incomplete kernel matrices. Moreover, (2) the method does not require any of the kernels to be complete a priori, and (3) can tackle non-linear kernels. The kernel completion is done by finding, from the set of available incomplete kernels, an appropriate set of related kernels for each missing entry. These aspects are necessary in practical applications such as integrating legacy data sets, learning under sensor failures and learning when measurements are costly for some of the views. The proposed approach predicts missing rows by modelling both within-view and between-view relationships among kernel values. For within-view learning, we propose a new kernel approximation that generalizes and improves Nystrom approximation. We show, both on simulated data and real case studies, that the proposed method outperforms existing techniques in the settings where they are available, and extends applicability to new settings.

Estimating the Transmission Dynamics of Streptococcus pneumoniae from Strain Prevalence Data

Abstract: Summary. Streptococcus pneumoniae is a typical commensal bacterium causing severe diseases. Its prevalence is high among young children attending day care units, due to lower levels of acquired immunity and a high rate of infectious contacts between the attendees. Understanding the population dynamics of different strains of S.pneumoniae is necessary, for example, for making successful predictions of changes in the composition of the strain community under intervention policies. Here we analyze data on the strains of S. pneumoniae carried in attendees of day care units in the metropolitan area of Oslo, Norway. We introduce a variant of approximate Bayesian computation methods, which is suitable for estimating the parameters governing the transmission dynamics in a setting where small local populations of hosts are subject to epidemics of different pathogenic strains due to infections independently acquired from the community. We find evidence for strong between-strain competition, as the acquisition of other strains in the already colonized hosts is estimated to have a relative rate of 0.09 (95% credibility interval [0.06, 0.14]). We also predict the frequency and size distributions for epidemics within the day care unit, as well as other epidemiologically relevant features. The assumption of ecological neutrality between the strains is observed to be compatible with the data. Model validation checks and the consistency of our results with previous research support the validity of our conclusions.

The managed prosumer: evolving knowledge strategies in the design of information infrastructures

Abstract: This paper contributes to the reworking of the traditional concepts and methods of Science and Technology Studies that is necessary in order to analyse the development and use of social media and other emerging information infrastructures (IIs). Through long-term studies of the development of two contrasting IIs, the paper examines the prosumer-management strategies by which vendors manage their relationships with their diverse users. Despite the sharp differences between our cases – an online-game with social network features and traditional enterprise systems – we find striking homologies in the ways vendors manage the tensions underpinning the design and development of mass-market products. Thus their knowledge infrastructures – the set of tools and instruments through which vendors maintain an adequate understanding of their multiple users – change in the face of competing exigencies. Market expansion may favour ‘efficient’ quantitative user assessment methods and the construction of abstract user cat...