Top-bottom and front-behind decisions on rotated objects.

Examined 2 tasks requiring the perception of the spatial relationship between an object and a dot. 24 undergraduates decided whether a dot was nearer the top or bottom of rotated drawings of objects in a top-bottom task, and whether a dot was at the front of or behind rotated objects in a front-behind task. These 2 tasks were performed with the head upright and with the head tilted clockwise and counterclockwise in separate blocks of trials in order to dissociate retinal from environmental perceptual frames of reference. Response times increased approximately linearly with increasing departure from the orientation of the perceptual reference frame in both tasks; the magnitude of the effect was similar across tasks. In the head-tilted conditions, the perceptual frame of reference was located midway between the environmental and retinal upright for both tasks. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Equilibria in the systems C−O−S and C−O−S−H as related to sulfur recovery from sulfur dioxide

Equilibrium phase diagrams for the titled systems, showing gas composition as a function of temperature for the carbon and sulfur-saturation surfaces, were calculated from thermochemical data on the numerous gas species present. The recent experimental work of Drowart,et al ¹. was used to obtain consistent thermodynamic behavior for the seven vapor polymers of sulfur (S _n ,n=2 to 8). For the system C?O?S?H, only the pseudo-ternary at the constant atom ratio H/C=4.0 is presented. An iterative procedure, adapted for the digital computer, was used to solve the complex equilibria involved. The influence of the equilibrium chemistry on the design of processes to reduce SO₂ with C, CO, and CH₄ is discussed. In all cases, production of sulfur vapor reaches a sharp maximum at the gas composition having the atom ratio (H+C)/O =(1+X)/(2+X/2), whereX is the atom ratio H/C in the reducing agent. Reducing agents with lower values ofX yield better sulfur recovery because of the smaller residual amount of H₂S and SO₂ in the reacted gas.     

Fecal contamination and diarrheal pathogens on surfaces and in soils among Tanzanian households with and without improved sanitation

Little is known about the extent or pattern of environmental fecal contamination among households using low-cost, on-site sanitation facilities, or what role environmental contamination plays in the transmission of diarrheal disease. A microbial survey of fecal contamination and selected diarrheal pathogens in soil (n = 200), surface (n = 120), and produce samples (n = 24) was conducted in peri-urban Bagamoyo, Tanzania, among 20 households using private pit latrines. All samples were analyzed for E. coli and enterococci. A subset was analyzed for enterovirus, rotavirus, norovirus GI, norovirus GII, diarrheagenic E. coli, and general and human-specific Bacteroidales fecal markers using molecular methods. Soil collected from the house floor had significantly higher concentrations of E. coli and enterococci than soil collected from the latrine floor. There was no significant difference in fecal indicator bacteria levels between households using pit latrines with a concrete slab (improved sanitation) versus those without a slab. These findings imply that the presence of a concrete slab does not affect the level of fecal contamination in the household environment in this setting. Human Bacteroidales, pathogenic E. coli, enterovirus, and rotavirus genes were detected in soil samples, suggesting that soil should be given more attention as a transmission pathway of diarrheal illness in low-income countries.     

Stable cholinergic-muscarinic and alpha-adrenergic inhibition of rat parotid adenylate cyclase

(-) Isoproterenol-stimulated adenylate cyclase activity of washed at parotid membrane preparations from gland slices previously treated with the alpha-adrenergic agonist, methoxamine, was inhibited approximately 30%. The action of methoxamine required exogenous Ca2+ and was blocked by the alpha-adrenergic blocking agent, phentolamine. Incubation of gland slices with carbamylcholine resulted in a dose-dependent inhibition (50%) of (-) isoproterenol-stimulated adenylate cyclase activity in washed membranes. The action of carbamylcholine was independent of exogenous Ca2+ and was blocked by preincubation with atropine. Cholinergic inhibition of parotid adenylate cyclase was compared to the cholinergic inhibition of adenylate cyclase in dog heart homogenates. While carbamylcholine caused a limited (20-30%) inhibition of basal and (-) isoproterenol-stimulated activities when added to dog heart homogenates, it failed to produce any effect in parotid homogenates prepared in an identical manner. Cholinergic inhibition of parotid adenylate cyclase activity was stable and persisted in washed particulate fractions while the inhibition in dog heart homogenates was reversible by washing. Cholinergic inhibition of adenylate cyclase was markedly dependent on the presence of GTP and was abolished when Mn2+ was subsituted for Mg2+ in both systems. Guanyl-5'-yl imidodiphosphate had little effect on the inhibition in parotid preparations but abolished the inhibition in heart homogenates. It is concluded that, in contrast to the cholinergic action in dog heart homogenates, the exposure of parotid slices to carbamylcholine results in a stable lesion in the adenylate cyclase activity.     

Computing extremal and approximate distances in graphs having unit cost edges

Summary Using binary search and a Strassen-like matrix multiplication algorithm we obtain efficient algorithms for computing the diameter, the radius, and other distance-related quantities associated with undirected and directed graphs having unit cost (unweighted) edges. Similar methods are used to find approximate values for the distances between all pairs of vertices, and if the graph satisfies certain regularity conditions to find the exact distances.A preliminary version of this research was presented at the Sixteenth Annual Allerton Conference on Communication, Control, and Computing and appears in the Proceedings for that conference. This work was supported in part by the Natural Sciences and Engineering Research Council of Canada under grant A4307 and by the Office of Naval Research under grant N00014-75-6-0752     

Biochemical and genetic characterization of Yra1p in budding yeast

Yra1p and its vertebrate homologues bind to the mRNA export factor Mex67p/TAP and are thought to play a role in mRNA export in vivo. To further characterize Yra1p, we used immunoaffinity chromatography to purify endogenous Yra1p complexes. These experiments demonstrated that two importin beta homologues (Kap123p and Pse1p) and the poly A tail-binding proteins Pab1p and Nab2p associate with Yra1p. The other major proteins that associate with Yra1p include proteins involved in mRNA and rRNA processing and the Yra1p-related protein Yra2p. Additional biochemical and genetic experiments suggest a close functional relationship between Yra1p and Yra2p. We generated a temperature-sensitive allele of YRA1 and used it to demonstrate that cells which lack the function of both Yra1p and Yra2p are able to exit a G0 arrest and go through several rounds of cell division before arresting. We also identified high-copy suppressors of the yra1-2 temperature-sensitive growth defect. These include SUB2, a splicing factor important in mRNA export, ULP1, a nuclear cysteine protease localized to the nuclear pore and involved in Smt3p/SUMO processing, and YRA2. Taken together, these results suggest that Yra1p has roles in diverse RNA processing events in addition to a role in mRNA export.     

Z-Beamlet: a multikilojoule, terawatt-class laser system

A large-aperture (30-cm) kilojoule-class Nd:glass laser system known as Z-Beamlet has been constructed to perform x-ray radiography of high-energy-density science experiments conducted on the Z facility at Sandia National Laboratories, Albuquerque, New Mexico. The laser, operating with typical pulse durations from 0.3 to 1.5 ns, employs a sequence of successively larger multipass amplifiers to achieve up to 3-kJ energy at 1054 nm. Large-aperture frequency conversion and long-distance beam transport can provide on-target energies of up to 1.5 kJ at 527 nm.