Structure-from-motion based on information at surface boundaries

Existing computational models of structurefrom-motion — the appearance of three-dimensional motion generated by moving two-dimensional patterns — are all based on variations of optical flow or feature point correspondence within the interior of single objects. Three separate phenomena provide strong evidence that in human vision, structure-from-motion is significantly affected by surface boundary cues. In the first, a rotating cylinder is seen, though no variation in optical flow exists across the apparent cylinder. In the second, the shape of the bounding contour of a moving pattern dominates the actual differential motion within the pattern. In the third, the appearance of independently moving objects changes significantly when the boundary between them becomes indistinct. We describe a simple computational model sufficient to account for these effects. The model is based on qualitative constraints relating possible object motions to patterns of flow, together with an understanding of the patterns of flow that can be discriminated in practice.     

Expert systems in histopathology. IV. The management of uncertainty.

Expert systems deal with data that are categorical and conceptual, that represent elements of fuzzy sets and that often, by themselves, do not allow an unequivocal decision. The management of uncertainty in expert systems thus becomes a crucial issue. It involves defining measures of uncertainty and procedures for combining accumulating evidence in a manner that properly considers the dependence structure of diagnostic clues. Probability theory offers valuable procedures for uncertainty assessment; however, their practical application in the domain of quantitative histopathology and histopathologic diagnosis can be problematic.     

Cardiovascular actions of adenosines, but not adenosine receptors, differ in rat and guinea pig

This study compared the structure-activity relationships of 16 analogues at the A1 and A2 adenosine receptors (A1AR, A2AR) of rat and guinea pig. Radioligand binding studies revealed no marked differences in the affinities of each analogue at the A1AR of brain cortex or the A2AR of brain striatum. Bioassay employing Langendorff heart preparations showed that the guinea pig is more sensitive than the rat to A1AR-mediated slowing of conduction through the atrioventricular node and, in some instances, to A2AR-mediated coronary vasodilation. That difference could reflect factors such as receptor density or efficacy of coupling to effector systems.     

Regulation of ANP secretion in insulin-dependent diabetes mellitus and the influence of autonomic neuropathy.

In order to determine the effect of diabetic autonomic neuropathy (DAN) on the atrial natriuretic peptide (ANP) response to dynamic stimuli, we studied the ANP response to 60 degrees head-up and 60 degrees leg-up tilt in diabetic subjects with (DAN + ve, n = 8) and without (DAN - ve, n = 8) evidence of autonomic neuropathy and seven matched non-diabetic controls. Mean baseline plasma ANP concentrations were similar in all three groups. Head-up tilt was associated with a fall in plasma ANP in all seven healthy controls (21.8 (16.8-30.7) to 16.8 (7.1-29.1), P = 0.06, mean (range)), seven of the eight DAN - ve (16.9 (6.5-33.7) to 8.5 (3.0-21.1), P = 0.015) and all eight DAN + ve subjects (27.3 (8.5-101.5) to 15.4 (1.0-67.6), P = 0.044). Leg-up tilt caused a rise in plasma ANP in six of the seven healthy controls (17.6 (7.5-27.9) to 22.4 (15.2-48.1), P = 0.041), six of the eight DAN - ve (12.5 (7.8-27.8) to 15.5 (7.3-31.3), P = 0.054) and seven of the eight DAN + ve subjects (18.2 (2.8-55.1) to 25.1 (4.5-92.8), P = 0.013). There was no significant difference in the fall in plasma ANP during head-up tilt or in the rise in plasma ANP during leg-up tilt between the three groups. We conclude that the regulation of ANP secretion is normal in diabetes mellitus, and is unaffected by the presence of autonomic neuropathy.     

Effect of straw on the behaviour of growing pigs

The effects of straw on the behaviour of young growing pigs were studied in two experiments. In Experiment 1, groups of three pigs, aged about 7 weeks, were housed in raised decks with or without straw bedding. Time-lapse video recording showed no major differences between treatments in the amount or daily pattern of overall activity and feeding. Detailed observations showed that bedding reduced the incidence of rooting and chewing on pen-mates, but had little effect on other social activities such as mounting and aggressive biting. Experiment 2 compared groups of eight growing pigs aged about 10 weeks, housed in floor pens with or without a small amount of straw provided daily in a rack. Pigs with straw concentrated more of their daily activity into the period when straw was fresh, but the total amount of overall activity and time spent feeding were not affected. Rooting and chewing of pen-mates were the only social activities reduced by the provision of fresh straw. In these studies, where straw was not required to compensate for deficiencies such as low temperatures or hunger, the one major function of straw was to provide a stimulus and outlet for rooting and chewing, with a resulting reduction in such activities directed at pen-mates.     

EMG muscle scanning: comparison to attached surface electrodes.

Electromyographic (EMG) muscle scanning measures brief samples of integrated muscle action potentials from individual muscles using a hand-held scanner with post-style electrodes. This "scanning" technique is widely used by biofeedback practitioners to quickly assess muscle activity in the diagnosis of musculoskeletal disorders. In an effort to compare muscle scanning with the established technique using attached surface electrodes, ten healthy subjects (25-35 years old) were scanned using 2-second sampling at five bilateral muscle sites while simultaneously monitoring the same sites with surface electrodes. This was repeated using 10-second scanning samplings. Pearson's product-moment correlations between scanning for 2 seconds and prolonged surface recording at all sites were 0.54-0.89. Scanning for 10 seconds improved the correlations to 0.68-0.91. EMG scanning for 2 seconds compares favorably with attached surface electrode recording. Comparisons are further improved by 10-second scans.     

Human creatine kinase genes on chromosomes 15 and 19, and proximity of the gene for the muscle form to the genes for apolipoprotein C2 and excision repair.

The human chromosomal assignments of genes of the creatine kinase (CK) family--loci for brain (CKBB), muscle (CKMM), and mitochondrial (CKMT) forms--were studied by Southern filter hybridization analysis of DNAs isolated from a human x rodent somatic cell hybrid clone panel. Probes for the 3'-noncoding sequences of human CKBB and CKMM hybridized concordantly only to DNAs from somatic cell hybrids containing chromosomes 14 and 19, respectively. Thus the earlier assignment of the gene coding for the CKBB isozyme to chromosome 14 was confirmed by molecular means, as was the provisional assignment of CKMM to the long arm of chromosome 19. A probe containing canine sequences for CKMM cross-hybridized with human sequences on chromosomes 14 and 19, a result consistent with the assignments of CKBB and CKMM. A probe containing human sequences for CKMT enabled the provisional assignment of CKMT to human chromosome 15. Independent hybrids with portions of the long arm of chromosome 19 missing indicated the order of genes on the long arm of chromosome 19 as being cen-GPI-(TGFB, CYP1)-[CKMM, (APOC2-ERCC1)]-(CGB, FTL). The unexpectedly more distal location of APOC2 among the genes on the long arm--and APOC2's close association with CKMM--is discussed with respect to the close linkage relationship of APOC2 to myotonic muscular dystrophy.     

Rapid changes in polyphosphoinositide metabolism associated with the response of Dunaliella salina to hypoosmotic shock

The inositol phospholipids phosphatidylinositol, phosphatidylinositol 4-phosphate (PIP), and phosphatidylinositol 4,5-bisphosphate (PIP2) comprise 14.8, 1.2, and 0.3 mol %, respectively, of Dunaliella salina phospholipids. In isolated plasma membrane fractions, PIP and PIP2 are highly concentrated, together comprising 9.5 mol % of plasmalemma phospholipids. The metabolism of these inositol phospholipids and phosphatidic acid (PA) is very rapid under normal growth conditions. Within 5 min after introduction of 32Pi into the growth medium, over 75% of lipid-bound label was found in these quantitatively minor phospholipids. Within 2 min after a sudden hypoosmotic shock, the levels of PIP2 and PIP dropped to 65 and 79%, respectively, of controls. Within the same time frame, PA rose to 141% of control values. These data suggest that a rapid breakdown of the polyphosphoinositides may mediate the profound morphological and physiological changes which allow this organism to survive drastic hypoosmotic stress. In contrast to hypoosmotic shock, hyperosmotic shock induced a rise in PIP2 levels to 131% of control values, whereas the level of PA dropped to 56% of controls after 4 min. These two different types of osmotic stress affect inositol phospholipid metabolism in a fundamentally opposite manner, with only hypoosmotic shock inducing a net decrease in polyphosphoinositides.