An assessment of the video image quality required in a remote vision guidance system for visually impaired pedestrians.

A study was carried out to determine the most acceptable quality of video images for use in remote guidance of visually impaired pedestrians. A video image clip of 20 s duration was captured using a digital camera, while walking a sample route. The video image clip was encoded at bit rates of 30 and 48 kbit/s, and frame rates of 10, 7.5, 5 and 2.7 fps. Two standard resolutions were used: Quarter Common Intermediate Format (QCIF) (176 x 144 pixels) and Common Intermediate Format (CIF) (352 x 288 pixels). Twelve participants gave their judgment on the picture update rate (smoothness of movement), the bit rate and the static resolution. The mean scores for total quality (five-point scale) ranged from 3.3 to 4.8, but there was no significant difference between them. The mean scores for smoothness (five-point scale) ranged from 3.0 to 4.7, but there was no significant difference between them. The mean score for the resolution of the QCIF video clips was 2.9 (SD = 0.9) and for the CIF recordings were 4.1 (SD = 0.7), but there was no significant difference between them. The majority of the participants were most comfortable with video which was transmitted at 48 kbit/s and 7.5 fps. Therefore, this quality can be considered satisfactory for remote guidance.

[Conformational study of drugs which affect I1-imidazoline receptors]. / Konformacné stúdium lieciv úcinkujúcich na I1-imidazolínové receptory.

Conformational analysis of five I1-receptor agonists in the neutral form (clonidine, moxonidine, rilmenidine, phentolamine, and phencyclidine) and one antagonist of I1-receptors (idazoxane) was carried out by means of the MM2 method. Structures of stable conformations of individual compounds were fully optimised. Degree of similarity of stable conformations was visualized. The proton affinities and lipophilicities of title compounds were also computed. It is obvious that all studied drugs except phencyclidine are able to occupy the same space. An important role for affinity of studied drugs towards I1-receptors can be played by their different hydrophobicity (logP = 1 az 2).

[Structure and activity relationship of propafenone and alkylesters of 2-and 4-[(3-propylamino-2-hydroxy)-propoxy]-phenylcarbamic acid]. / Vztah struktúry a úcinku propafenónu a alkylesterov kyseliny 2- a 4-[(3-propylamino-2-hydroxy)-propoxy]-fenylkarbámovej.

Conformation analysis was performed in propaphenone and two potential antiarrhythmic agents of the carbamate type, employing the method of molecular mechanics for calculations. Energetically stable conformers were optimized by means of the quantumchemical method AM1 and the optimized structures were used to construct the pharmacophore. Using the programme Chem-X, four groups of stable conformations of these drug were found, and comparisons by means of the molecular graphic method were employed to graphically visualize the degree of their similarity and to determine the interatomic distances of the groups with free electron pairs and a lipophilic aromatic nucleus.