Reflective Interaction in Virtual Environments

The proliferation of projection-based systems in recent years resulted in a variety of specialised interaction techniques that make Virtual Environments a better man machine interface. However, the success of these techniques and metaphors is directly linked to the interaction and tracking devices used in their implementation. Users find that devices such as the data glove, stylus or joystick can be expensive and cumbersome especially for the inexperienced. A variety of approaches exist that make use of computer vision for tracking gestures or for achieving wireless interaction. Typically these approaches involve the use of a two- camera pair, or a stereoscopic camera.
Our approach uses only one camera and one or more reflective surfaces, to effectively and accurately calculate 3D information. The calibration time is minimal and it allows for a very flexible positioning of the camera and reflecting surfaces. Wireless interaction and natural interaction metaphors in the user's physical space can be created using our method. The method can be combined easily and effectively with projection-based systems as well as with standard and stereoscopic monitors, or extended for the use in augmented spaces. It is an inexpensive method that uses commonly available hardware and therefore its application areas as an interaction and tracking device, include games and use of virtual environments in education. In this paper, we describe the method and its use as an interaction device in two applications, and conclude with a discussion on its advantages and limitations.     

Identification of mutations in cystatin B, the gene responsible for the Unverricht-Lundborg type of progressive myoclonus epilepsy (EPM1)

Progressive myoclonus epilepsy (EPM1) is an autosomal recessive disorder, characterized by severe, stimulus-sensitive myoclonus and tonic-clonic seizures. The EPM1 locus was mapped to within 0.3 cM from PFKL in chromosome 21q22.3. The gene for the proteinase inhibitor cystatin B was recently localized in the EPM1 critical region, and mutations were identified in two EPM1 families. We have identified six nucleotide changes in the cystatin B gene of non-Finnish EPM1 families from northern Africa and Europe. The 426G-->C change in exon 1 results in a Gly4Arg substitution and is the first missense mutation described that is associated with EPM1. Molecular modeling predicts that this substitution severely affects the contact of cystatin B with papain. Mutations in the invariant AG dinucleotides of the acceptor sites of introns 1 and 2 probably result in abnormal splicing. A deletion of two nucleotides in exon 3 produces a frameshift and truncates the protein. Therefore, these four mutations are all predicted to impair the production of functional protein. These mutations were found in 7 of the 29 unrelated EPM1 patients analyzed, in homozygosity in 1, and in heterozygosity in the others. The remaining two sequence changes, 431G-->T and 2575A-->G, probably represent polymorphic variants. In addition, a tandem repeat in the 5' UTR (CCCCGCCCCGCG) is present two or three times in normal alleles. It is peculiar that in the majority of patients no mutations exist within the exons and splice sites of the cystatin B gene.     

Virtual studios: an overview

Virtual studio systems began as experimental prototypes that extended traditional chromakeying. Now commercial products based on graphics supercomputers are commonly used for broadcast production. We discuss this evolution and consider extensions, alternative approaches, and issues facing broadcasters who introduce virtual studio systems     

Ndebele painting in VR

The Ndebele tribe of southern Africa consists of four subtribes. The Ndzundza is the only Ndebele group practising the decorative arts of painting and beadwork. The craft of producing striking, colourful and geometrical artwork has become their most distinctive feature. The Ndebele wall painting's work and richness provided the inspiration for our project. We created a virtual environment (VE) and an interaction method that facilitates the creation, painting and mapping of these paintings on different 2D and 3D surfaces. Designing tools for painting in VEs presents many challenges. We must support design without restricting the artist's creative process. Commercially available tools mainly work in a 2D environment and use specialized interaction devices. Design tools in VEs use a mixture of 2D and 3D interaction devices and metaphors and mainly target 3D modeling for a variety of application areas. In our project-a research interface for Ndebele wall painting in a VE-we focus on the specific process of wall painting and keep our interaction metaphors as close as possible to the real wall-painting process, At the same time, the project takes advantage of the many possibilities that a VE can offer in terms of production speed and mapping on to different surfaces, among others     

Initial use of 1-hydroxybenzotriazole in the chemistry of group 12 metals: An 1D zinc(II) coordination polymer and a mononuclear cadmium(II) complex containing the deprotonated ligand in a novel monodentate ligation mode

The chemistry of 1-hydroxybenzotriazole (btaOH) with the group 12 metal ions Zn(II) and Cd(II) resulted in the 1D coordination polymer [Zn(btaO)₂]_n (1) and the mononuclear complex [Cd(btaO)₂(H₂O)₄] · 3H₂O (2 · 3H₂O), respectively. Polymer 1 forms double-stranded chains which are further supported by weak C–H?O hydrogen bonds resulting in a pcu (primitive cubic) rod packing. The mononuclear complexes of 2 form undulating hydrogen bonded layers while the lattice water molecules form 1D hydrogen bonded tapes, comprising 4- and 6-membered rings, within the layers and bridge them to the third dimension. The thermal and optical properties of both compounds are presented. IR data are discussed in terms of the chemical composition of the compounds and the coordination mode of btaO^?.