Orienting response and detection of thalamic stimulation: Mechanism of perceptual learning in the cat.

Hypothesized that attention facilitates the neural mechanisms that permit responding to significant input. In the present experiment, the orienting response was used as an index of the action of the neural mechanisms of attention in 7 cats. Results demonstrate that Ss could not use thalamic stimulation as a signal to perform a behavioral response when stimulus intensities were too weak to evoke orienting behavior. Responses were quickly learned at higher intensities of stimulation, and with continued training, the Ss were able to respond to the weaker, previously ineffective stimulus. This increase in sensitivity was not due to changes in tonic arousal and appeared to be relatively specific to the stimulated nucleus. The procedures may be useful in exploring the neural mechanisms of perceptual learning. Findings are consistent with B. Libet's (1982) report that EPs in sensory cortex may not be sufficient to produce conscious experience in humans and suggest that input to the cerebral cortex from sense organs is not a sufficient condition even for discrimination. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultra large scale static rams

Using a patented defect avoidance technique, high yield production of high density SRAM devices (ULSI SRAMs) can be achieved one process generation ahead of the rest of the industry. Production wafer yields as high as 100% and long-term average yields above 80% are reported on Inova's monolithic, 1.2μ, 320 square mm, one megabit SRAM demonstrating a practical method of achieving wafer scale integration. A yield model is presented and used to determine the optimized architecture and redundancy scheme for Inova's four megabit SRAM and to predict yield as a function of defect density. Achievement of a working 8M-bit experimental device using a 1.2μ process is also reported.     

Selecting air handling units

Proper selection of air handling unit components plays a critical role in occupant acceptance of a conditioned space.     

Energy budgets for office buildings?

To study the feasibility of devising energy performance codes – energy budgets – for office buildings, a major Canadian research project monitored the performance of existing buildings to verify a computer programme, which then provided a model for testing the effect on energy consumption of independent variables. The results showed that building height is far more important than size, and that shape and climatic location can be allowed for in relatively simple formulae. The knowledge thus gained, when applied to calculate the effect of better energysaving measures for the office blocks chosen, indicated potential savings of 44–50 per cent with little capital cost.     

The effect of heat treatment on the fatigue strength of microknurled Ti-6Al-4V

Microknurling, a high pressure surface indentation technique, was devised as an alternative to traditional heat-bonded porous coatings found on many orthopedic implants designed for fixation by tissue ingrowth. Heat-bonded porous coating can cause at the surface of an implant stress concentrations that reduce fatigue strength. However, microknurling may reduce stress intensification without eliminating it. Thus the purpose of this work was to explore surface thermal/mechanical processing of Ti-6Al-4V to improve the fatigue strength of microknurled specimens via the production of a Ti-6Al-4V dual microstructure. The latter consists of a surface layer of equiaxed grains known to be effective against crack initiation and a bulk microstructure of lamellar grains that possesses optimum fatigue crack propagation resistance. Rotating-bending fatigue tests showed that such a microstructure had some benefits, but this was offset by the reduction in compressive strains imparted to the surface by the heat treatments needed to obtain this microstructure.     

The role of cardiac troponin T and other new biochemical markers in evaluation and risk stratification of patients with acute chest pain syndromes

Electrocochleography (ECochG) was used to evaluate cochlear function in guinea pigs with experimentally induced endolymphatic hydrops (ELH) before and after osmotic dehydration with either glycerol or urea. We surgically induced ELH in the right ears of 9 guinea pigs, while the right ears of 6 guinea pigs received a sham operation. The left ears of the 15 animals constituted the normal group. Eight weeks after surgery, summating potential (SP) and action potential (AP) amplitudes were measured prior to and following the administration of glycerol or urea. The SPs and SP/AP ratios were reduced in all groups, with no significant differences among groups or between dehydrating agents. Some of the hydropic ears, however, did show an increased AP threshold and a recruitment effect. In measurements from 6 additional animals, serum osmolarity increased more with urea than with glycerol. The guinea pig model remains valuable for investigation of ELH, even though it differs in significant respects from ELH in humans.     

Lipid concentration profile across the wall of pseudoatherosclerotic synthetic arterial prostheses using FTIR microspectroscopy

FTIR microscopy is a versatile technique successfully used to probe the subcellular chemical composition of atherosclerostic arterial walls. To design new vascular substitutes that resist lipid uptake (the major cause of the phenomenon referred to as atherosclerosis-like), identifying and understanding lipid distribution within the pseudoatherosclerosed arterial prostheses is of prime importance. Until now, the amount of lipids present within arterial prostheses that had been explanted from either animals (during in vivo trials) or humans (after the failure of vascular grafts) or had been submitted to in vitro investigations could only be measured through the use of histological techniques or radioactive labeling methods. We present here a novel method to quantitatively measure the lipid concentration profile within the wall of arterial prostheses by means of Fourier transform infrared microspectroscopy. Essentially, prostheses are fixed in a 1% osmium tetraoxide aqueous solution under vacuum and radially cut with a 5-micron thickness with a microtome. The sections are then placed onto BaF2 windows and observed with a microscope attached to a FTIR spectrometer with a 30 microns x 50 microns sampling area. The lipid concentration profile is obtained by scanning the prosthesis wall from the inner to the outer surface and reporting the corresponding integrated absorbance between 2700 and 3100 cm(-1) against a calibration curve. The application of this technique constitutes the first quantitative measurement of the concentration of biological molecules within the wall of artificial arterial substitute.     

A factorial study of dexterity tests.

"The advent of the transistor and other industrial operations involving very small items brings a need for a better understanding of very fine manipulative work." 100 students were given 15 tests to take. Thurstone's centroid method was used for the analysis. "The identified factors include neither the tweezer dexterity favor hypothesized, nor the separate finger dexterity factor found in previous studies with the same tests." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reproducibility of coronary arteriographic reading in the coronary artery surgery study (CASS)

Eight hundred seventy arteriograms from the Coronary Artery Surgery Study (CASS) were independently read by readers at two different clinics to evaluate the reproducibility of the interpretation of coronary arteriograms. Among proximal segments, the interpretation of lesions of the left main coronary artery were the least reproducible, P less than .02. When one angiographer reads a stenosis of 50% or more in the left main coronary artery, it is estimated that a second reader will report no lesion 18.6% of the time. In 94.7% of the films, the number of significantly (greater than or equal to 70% stenosis) diseased vessels was the same for both readers (72.1%) or differed by one vessel (22.6%). The reproducibility of interpretation of films of good or acceptable quality or completeness was better than the reproducibility of readings of arteriograms judged to be of poor quality or incomplete studies. The mean absolute difference between readings of the percent stenosis decreased over the time of the patient enrollment, 1975 to 1978. This may have resulted from major collaborative efforts made during the course of the study to improve the quality of angiography and to standardize the reading of the cine films.     

Drying Characteristics and Moisture Diffusivity of Distillers' Spent Grains Dried in Superheated Steam

Distillers' spent grain pellets were prepared from material with an initial moisture content of 25% (wb). These pellets were dried in pairs using superheated steam at 120°C in two orientations, horizontal and vertical. The drying characteristics, modeled by the Page equation, showed that there was a significant difference between orientations. The overall moisture diffusivity was calculated using a finite cylinder model based on Fick's law of diffusion accounting for a change in dimensions over the course of drying. The overall diffusivity values ranged from 4.08 × 10^?10 to 1.48 × 10^?8 m²/s.