User interfaces for communication bridges across the digital divide

Connecting people across the “digital divide” is as much a social effort as a technological one. We are developing a community-centred approach to learn how interaction techniques can compensate for poor communication across the digital divide. We have incorporated the lessons learned regarding social intelligence design in an abstraction and in a device called the SoftBridge. The SoftBridge allows communication to flow from endpoints through adapters, getting converted if necessary, and out to destination endpoints. Field trials are underway with two communities in South Africa: disadvantaged Deaf users and an isolated rural community. Initial lessons learned show that we have to design user interfaces that allow users to understand and cope with delay. We also learned that social concerns are often more important than the technical issues in designing such systems.     

GD3/proteosome vaccines induce consistent IgM antibodies against the ganglioside GD3

The gangliosides of melanoma and other tumours of neuroectodermal origin are suitable targets for immune intervention with tumour vaccines. The optimal vaccines in current use contain ganglioside plus bacillus Calmette-Guérin and induce considerable morbidity. We have screened a variety of new adjuvants in the mouse, and describe one antigen-delivery system, proteosomes, which is especially effective. Highly hydrophobic Neisserial outer membrane proteins (OMP) form multimolecular liposome-like vesicular structures termed proteosomes which can readily incorporate amphiphilic molecules such as GD3 ganglioside. The optimal GD3/proteosome vaccine formulation for induction of GD3 antibodies in the mouse is determined. Interestingly, the use of potent immunological adjuvants in addition to proteosomes augments the IgM and IgG antibody titres against OMP in these vaccines but GD3 antibody titres are unaffected. The application of proteosomes to enhance the immune response to GD3 extends the concept of the proteosome immunopotentiating system from lipopeptides to amphipathic carbohydrate epitopes such as cell-surface gangliosides. The demonstrated safety of meningococcal OMP in humans and the data in mice presented here suggest that proteosome vaccines have potential for augmenting the immunogenicity of amphipathic tumour antigens in humans.     

Neuropeptide Y and luteinizing hormone releasing hormone synergize to stimulate the development of cellular follicle-stimulating hormone in the hamster adenohypophysis

Luteinizing hormone releasing hormone (LHRH) stimulates the development of cellular FSH immunoreactivity in the perinatal hamster adenohypophysis. Because neuropeptide Y (NPY) can act directly on rat adenohypophysial cells to stimulate FSH and LH release and potentiate the stimulatory effect of LHRH on FSH and LH release, we investigated the effects of NPY alone and in combination with a low, ineffective dose of LHRH on inducing cellular FSH immunoreactivity in the neonatal hamster adenohypophysis. Neonatal female pituitary glands were grafted beneath the right renal capsules of hypophysectomized-ovariectomized adult hamster hosts with a catheter implanted in the external jugular vein. After treatment, hosts were decapitated and graft tissue was stained for FSH and LH immunoreactivity. The mean percentage of adenohypophysial cells that stained for FSH was low (2.8%) in grafts in hosts infused continuously with heparinized saline vehicle for 7 days. In other hosts, peptides were pulsed through the catheter every 12 h for 7 days. The mean percentage of FSH cells also was low after pulsing 6 ng LHRH or 2 micrograms NPY but increased substantially when the two peptides were pulsed simultaneously. No differences in the mean percentage of LH cells existed between any of the groups. The results demonstrate that NPY and LHRH can synergize to induce cellular FSH immunoreactivity in the neonatal female hamster.     

Two new decoding algorithms for Reed-Solomon codes

The subject of decoding Reed-Solomon codes is considered. By reformulating the Berlekamp and Welch key equation and introducing new versions of this key equation, two new decoding algorithms for Reed-Solomon codes will be presented. The two new decoding algorithms are significant for three reasons. Firstly the new equations and algorithms represent a novel approach to the extensively researched problem of decoding Reed-Solomon codes. Secondly the algorithms have algorithmic and implementation complexity comparable to existing decoding algorithms, and as such present a viable solution for decoding Reed-Solomon codes. Thirdly the new ideas presented suggest a direction for future research. The first algorithm uses the extended Euclidean algorithm and is very efficient for a systolic VLSI implementation. The second decoding algorithm presented is similar in nature to the original decoding algorithm of Peterson except that the syndromes do not need to be computed and the remainders are used directly. It has a regular structure and will be efficient for implementation only for correcting a small number of errors. A systolic design for computing the Lagrange interpolation of a polynomial, which is needed for the first decoding algorithm, is also presented.This research was supported by a grant from the Canadian Institute for Telecommunications Research under the NCE program of the Government of Canada     

Bayesian Availability Using Gamma Distributed Priors

Classical statistical estimation techniques have limited usage in predicting system availability when a system, e.g., a computer or telecommunications system, is highly reliable. A Bayesian solution is suggested in this paper. Gamma priors, which are rich in shapes, are assigned to the scale parameters of a gamma distributed component on-time and off-time. Estimation of the gamma priors follows engineer's past experiences for reliability modeling. Both steady-state and instantaneous availabilities are derived using Bayes Theorem. An illustration highlights the assessment and evaluation of the proposed availability measure.     

Anisotropies in visual motion perception: a fresh look

We measured motion-detection and motion-discrimination performance for different directions of motion, using stochastic motion sequences. Random-dot cinematograms containing 200 dots in a circular aperture were used as stimuli in a two-interval forced-choice procedure. In the motion-detection experiment, observers judged which of two intervals contained weak coherent motion, the other internal containing random motion only. In the direction-discrimination experiment, observers viewed a standard direction of motion followed by comparison motion in a slightly different direction. Observers indicated whether the comparison was clockwise or counterclockwise, relative to the standard. Twelve directions of motion were tested in the detection task and five standard directions (three cardinal directions and two oblique directions) in the discrimination task. Detection thresholds were invariant with direction of motion, but direction-discrimination thresholds were significantly higher for motion in oblique directions, even at low-coherence levels. Results from control conditions ruled out monitor artifacts and indicate that the oblique effect is relative to retinal coordinates. These results have broad implications for computational and physiological models of motion perception.