Eva Hladká

High-definition multimedia for multiparty low-latency interactive communication

We describe a high-quality collaborative environment that uses High-Definition (HD) video to achieve near realistic perception of a remote site. The capture part, consisting of a HD camera, Centaurus HD-SDI capture card, and UltraGrid software, produces a 1.5 Gbps UDP data stream of uncompressed HD video that is transferred over a 10GE network interface to the high-speed IP network. The HD video stream displaying uses either a software-based solution with color depth down-sampling and field de-interlacing, or another Centaurus card. Data distribution to individual participants of the videoconference is achieved using a user-controlled UDP packet reflector based on the Active Element idea. The viability of this system has been demonstrated at the iGrid 2005 conference for a three-way high quality videoconference among sites in the Czech Republic, Louisiana, and California.

Scalability and robustness of virtual multicast for synchronous multimedia distribution

A simple UDP packet reflector for virtual multicast multimedia transfer is extended to form a distributed system of active elements that solves the scalability problem of otherwise centralistic approach. The robustness of such virtual multicast delivery system is also discussed and shown to be better than the native multicast can offer. The maximum latency, important for multimedia transfer and related to the number of hops through the network of active elements, can be kept bounded. Possible support for synchronized multi-stream transfer is also discussed.

User-Empowered Programmable Network Support for Collaborative Environment

We introduce a user-empowered UDP packet reflector to create virtual multicasting environments as an overlay on top of current unicast networks. The end-users’ ability to fully control this environment by a specific communication protocol is the main advantage of our approach. Serializing the parallel communication schema for group communication allows us to introduce special features that are possible in unicast communication only. Similar to working with programmable routers, users can submit their own modules, which can be linked into the reflector and perform user-specific operations (filtering, transcoding etc.). The reflector is the basic element of the overlay network support for the user-empowered group communication in collaborative environments.

An Active Network Architecture: Distributed Computer or Transport Medium

Future computer networks must be more flexible and faster then today. Active network paradigm is the way how to add flexibility to networks. During the last five years, several active network architecture models were presented. A new one, based on model of active nodes is presented here. The key features of this architecture are the separation of session or connection management functions from the bulk data packet processing functions and associated session management protocol that facilitates user control over active network processing. This architecture is designed to be sufficiently general to accommodate and build on top of any packet-based networking technology. The description of the model is followed by brief of prototype implementation using PC-class computers with NetBSD operating system.

An Electronic Infrastructure for Research and Treatment of the Thalassemias and Other Hemoglobinopathies: The Euro-Mediterranean Ithanet Project

Hemoglobin (Hb) disorders are common, potentially lethal monogenic diseases, posing a global health challenge. With worldwide migration and intermixing of carriers, demanding flexible health planning and patient care, hemoglobinopathies may serve as a paradigm for the use of electronic infrastructure tools in the collection of data, the dissemination of knowledge, the harmonization of treatment, and the coordination of research and preventive programs. ITHANET, a network covering thalassemias and other hemoglobinopathies, comprises 26 organizations from 16 countries, including non-European countries of origin for these diseases (Egypt, Israel, Lebanon, Tunisia and Turkey). Using electronic infrastructure tools, ITHANET aims to strengthen cross-border communication and data transfer, cooperative research and treatment of thalassemia, and to improve support and information of those affected by hemoglobinopathies. Moreover, the consortium has established the ITHANET Portal, a novel web-based instrument for the dissemination of information on hemoglobinopathies to researchers, clinicians and patients. The ITHANET Portal is a growing public resource, providing forums for discussion and research coordination, and giving access to courses and databases organized by ITHANET partners. Already a popular repository for diagnostic protocols and news related to hemoglobinopathies, the ITHANET Portal also provides a searchable, extendable database of thalassemia mutations and associated background information. The experience of ITHANET is exemplary for a consortium bringing together disparate organizations from heterogeneous partner countries to face a common health challenge. The ITHANET Portal as a web-based tool born out of this experience amends some of the problems encountered and facilitates education and international exchange of data and expertise for hemoglobinopathies.

Multimedia support for individualized learning

Multimedia play growing role in learning. It is possible to use multimedia support not only for demonstrations during the lectures but also to create multimedia material for learning as record of the lecture. Recording lectures and providing recorded material both on-line and off-line is a way to solve otherwise contradictory requirements: how to substantially increase the number of students while keeping the number of teachers and their load constant or even decreasing. Design and implementation of a system for supporting individualized learning process in both synchronous and asynchronous manner are discussed as well as practical experiences with this system. Important role in learning process plays information accessibility and this feature is achieved by the indexing of the lecture record.

Transparent security for collaborative environments

Current collaborative tools are often not able to profit from existing systems for user management. It is therefore necessary for collaborative systems to administrate their users using their own solutions, which may not be adequate in terms of scalability or security. Many users may also experience problems working with authentication credentials (e.g. digital certificates) employed by collaborative systems. In this paper, we propose a general framework to provide easy-to-use yet secure access to collaborative systems, which offers a general middleware layer to accommodate various types of collaborative tools. The framework utilizes the emerging model of federations, which allows to provide a user-friendly means of logging in to a collaborative system as well as a solid basis for specifying access control policies. The framework handles all security aspects in a transparent way without requiring the users to perform complicated tasks. Using user attributes maintained in the federation, it is also possible to implement efficient and dynamic group management of the collaborating users.

Videoconferencing design for remote groups

Videoconferencing has emerged as a popular method of remote communication. The design of a videoconferencing environment strongly influences the communication efficiency and user satisfaction. Various studies on perceived effects of videoconferencing environments and their parameters have been done, however, they primarily focused on dyadic conversation. This paper describes an exploratory study on the effects on remote groups communication. Beginning with the standard environment, a videoconferencing design has been developed iteratively according to information obtained from the experimental group. Two new videoconferencing environment designs are introduced to suit the group conversation needs better and bring the group videoconference closer to face-to-face communication.

Cryptography enhanced ad-hoc approach to P2P overlays

We address the problem of a secure direct communication of two arbitrary peers in a P2P network without knowing each others IP addresses. An efficient solution to this problem will provide a practically usable way of communication to privacy-sensitive P2P applications. Traditionally, P2P architectures view this problem as a problem of mutual anonymity of a message sender and receiver, but usual solutions suffer from various inefficiencies or complexities. By looking at the problem from a perspective of an ad-hoc network, we are able to apply a familiar approach of multihop communication and ad-hoc routing algorithms to a P2P overlay. Introduced usage of a public key as a nodes identifier adds further security features, including data integrity through digital signatures, or end-to-end encryption. Proposed P2P overlay has been successfully used for building a decentralised cryptocurrency exchange Coincer.

22. Comparison of the methods for brain parcellation

In recent studies many scientists tend to examine functional connectivity with the help of graph theory algorithms, especially when studying resting-state fMRI data. The graph theory approach is based on the cortex parcellation – dividing it to disjoint areas and analyzing the relations between these areas. This work tries to compare results of parcellation by three types of anatomical atlases – AAL atlas, atlas of Brodmann areas and parcellation to gyri and sulci. We also use different approaches to compute representative signal for each area and compare how the representative explains data. We used mean signal, first, second and third principal component as the typical signal and we computed significances of each representative type by percentage of area variability explained by this signal. We found that the representative explains less than 50% of the variability in the area no matter which type of representative we chose. This could have been caused by present noise or the area size. The representative created from mean signal is almost the same as the first principal component signal regarding the percentage of explained variability. However, 1st PCA component can capture the inhomogeneity of the area and therefore can suggest possible dividing of the area which would result in smaller areas better explained by their separate representatives. Our comparison of anatomical atlases brought one compex conclusion – areas created according to Brodmann and AAL atlases have lower mean variance and higher mean explained variabillity than areas specified by atlas of gyri and sulci. To conclude we propose to use the AAL atlas above the other two types of atlases. In future the comparison of parcellation by anatomical atlases and data driven analysis would be interesting.