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PubMed2005

Discrimination of speed in 5-year-olds and adults: are children up to speed?

We compared thresholds for discriminating changes in speed by 5-year-olds and adults for two reference speeds: 1.5 and 6 degrees s(-1). Both adults and 5-year-olds were more sensitive to changes from the faster than from the slower reference speed. Five-year-olds were less sensitive than adults at both reference speeds but significantly more immature at the slower (1.5 degrees s(-1)) than at the faster (6 degrees s(-1)) reference speed. The findings suggest that the mechanisms underlying speed discrimination are immature in 5-year-olds, especially those that process slower speeds.

Acceleration↗
PubMed1999

Attention and information processing efficiency in patients with Chronic Fatigue Syndrome.

In this study a battery of attentional tests and a verbal memory task were administered to outpatients with Chronic Fatigue Syndrome (CFS) in order to evaluate aspects of attention that have not been explored in this group to date. In addition, this study was designed to further examine memory function and to extend the few reports investigating the rate of cognitive processing independent of motor speed and the possibility of a modality-specific impairment of information processing. Twenty-nine patients with CFS and 22 healthy controls matched for age, gender, intelligence, and education were included in this study. The results show that patients with CFS do not seem to be impaired for modification of phasic arousal level, nor for visual selective attention requiring shifting of attention in the visuospatial field. The results further support the presence of reduced information processing speed and efficiency, and strengthen the evidence of a global non-modality-specific attentional dysfunction in patients with CFS. In this study the poor performance of patients with CFS on recall of verbal information was due to poor initial storage rather than to a retrieval failure.

Adult↗
PubMed1993

Influence of time and exposure to air on radiographic contrast and relative film speed of three rapid dental film processing solutions.

The aim of this study was to determine the influence of exposure to air and time on the radiographic contrast and relative film speed of three processing solutions. A modified aluminium step-wedge phantom was used to expose varying numbers of Kodak Ektaspeed films daily for periods up to 57 days. The radiographic contrast and relative film speed were determined each day using a digital densitometer. Data obtained were analysed statistically, using Duncan's Multiple Range Test, and a 3-Factor ANOVA. It was found that, for radiographic contrast, Insta-Neg gave the highest values, followed by Kolchem and Ultra-Neg. For relative film speed, Kolchem gave the highest values, followed by Insta-Neg and Ultra-Neg. Both radiographic contrast and relative film speed decreased with the passage of time. Processing solutions kept in closed containers continued to perform efficiently for a longer time than those in open containers. The useful period was found to exceed that which is usually recommended.

Air↗
PubMed1996

Use of total of Escherichia coli counts to assess the hygienic characteristics of a beef carcass dressing process.

Swab samples were obtained from 3 sites on the surfaces of beef carcasses passing through a high speed dressing process, with 24 samples from each site being obtained at each of 4 points in the process. The aerobic microflora recovered from each swab after incubation at 25 degrees C was enumerated and characterized, and numbers of coliforms and Escherichia coli were determined. The data on aerobic flora indicated that skinning results in similar contamination of all 3 sites, that further deposition of bacteria at the brisket site occurs after skinning, and that trimming and washing achieve modest decontamination of the neck and brisket site, and extensive decontamination of the rump site. Changes in flora compositions during processing were too limited to much affect the assessment based on the aerobic flora total counts alone. The E. coli data indicated that during skinning the rump site was more heavily contaminated with faecal organisms than the other sites, that contamination of the brisket site is little altered between skinning and carcass splitting, although there is an extensive redistribution of E. coli at the neck site and sporadic, limited decontamination of the rump site, and that trimming and washing do not decontaminate the neck or rump sites, but that the rump site is extensively decontaminated by trimming. There was good correlation between E. coli and coliform counts, but weak correlation between E. coli and aerobic, 25 degrees C, counts. The findings suggest that assessments of beef carcass dressing processes for Hazard Analysis: Critical Control Point (HACCP) purposes should be based on enumerations of E. coli, or perhaps coliforms, rather than of the aerobic flora, to avoid important misunderstandings of the hygienic effects of the various operations in a process.

Animals↗
PubMedDate not supplied

The relation of affect to attention and learning in infancy.

The relation of positive affect to attention and learning was examined in 5-, 7-, and 9-month-olds (N = 84). Affect and attention were assessed while the infants inspected a photograph. Affect was rated globally, for overall mood, and specifically, for amount of time smiling. Attention was indexed by the duration of the infant's longest (or peak) look, a measure previously linked to differential cognitive performance. At all ages, positive affect (shown by approximately half the infants) was associated with long look durations and slower learning, as assessed on a task in which infants learned to distinguish a familiar face from a series of novel faces. By contrast, neutral affect was associated with short looks and faster learning. Affect and look duration had synergistic effects, in that learning was faster than expected for infants who displayed both short looks and neutral affect. These findings are compatible with adult research that links positive affect to less analytical processing, and provide the first evidence that affect may be associated with the speed of processing differences implicated in short and long looking.

Affect↗
PubMedDate not supplied

Rubber contact dermatitis in patients attended at Walter Cantídio Hospital, Federal University of Ceará, Brasil.

Nowadays 70% of the world's rubber supply is synthesized artificially. The process involved in its manufacture is vulcanization which requires many chemical substances for speeding the process, as antioxidants to prevent deterioration of rubber, or others. These substances may constitute important sensitizers and thus be responsible for dermatological diseases like contact dermatitis. The objective of this study is to search for the main sensitizers among these rubber chemicals in a population mostly composed by women of a tropical country and compare the results with the ones obtained from previous studies which tested populations mainly composed by men and on different climates.

Brazil↗
PubMed2006

Differences in cognitive performance during pregnancy and early motherhood.

BACKGROUND: Pregnancy has often been associated with cognitive deficits, but results are equivocal and little is known about how these deficits progress with time. METHOD: In the present study, the cognitive performance of 57 pregnant women was compared with that of 50 non-pregnant women matched for age and education, using a well-validated neurocognitive test battery at weeks 14, 17, 29, and 36 of pregnancy, and 32 weeks postpartum in the pregnant group and at comparable times in the non-pregnant group. RESULTS: Memory encoding and retrieval, as assessed with a word learning task, were significantly lower in the pregnant group than in the control group. This difference was still present at 32 weeks after delivery. The two groups did not differ in complex speed of information processing at any of the test moments; however, general speed of information processing was significantly compromised during early motherhood (week 32 postpartum). CONCLUSION: Thus, memory performance is poorer during pregnancy and early motherhood, and general speed of information processing is slower during early motherhood.

Adult↗
PubMed2006

Information processing following mild head injury.

Research has shown that individuals who have sustained mild head injury demonstrate a slowed speed of processing that is exacerbated by fatigue/stress. We administered the Paced Auditory Serial Addition Test (PASAT) at the beginning and at the end of a 4-h experimental protocol to determine whether fatigue or a stressor would result in poorer scores for individuals who had previously sustained mild head injury. A significant improvement was found between the first and second administration for both head-injured and control subjects, but difference scores revealed a significant between-groups difference for the first of the four trials, with the head-injured participants performing worse than controls. Apparently, head-injured participants were slower to develop, as well as slower to regain, a means of efficiently processing rapidly presented information.

Adolescent↗
PubMed2004

Electrophysiological evidence for independent speed channels in human motion processing.

A variety of psychophysical studies suggests that motion perception in humans is mediated by at least two speed-tuned channels. To study the neurophysiological underpinnings of these channels in the human visual cortex, we recorded visual evoked potentials (VEPs) to motion onset. We applied an adaptation paradigm that allowed us (a) to isolate and extract direction-specific cortical responses and (b) to assess cross-adaptation in the speed domain. VEPs resulting from the onset of left- or rightward motion at either low or high speeds were recorded from three occipital recording sites in 11 subjects. For each of these test stimuli, responses were collected after adaptation to one of five different conditions: a static adaptation pattern (baseline), adaptation to low-speed motion (3.5 degrees/s) either in the same or in the opposite direction as the test, or adaptation to high-speed motion (32 degrees/s) either in the same or in the opposite direction as the test. We report considerable direction-specific adaptation for same adaptation and test speeds (by 28-37% of baseline response; p <.002), whereas there was no direction-specific adaptation across speeds. We supplement these electrophysiological data with corresponding psychophysical results. The lack of direction-specific cross-adaptation in the speed domain demonstrated with physiological and psychophysical techniques supports models of at least two speed-tuned channels in the human motion system.

Adaptation, Ocular↗
PubMed2001

Chemical nanoprinting: a novel method for fabricating DNA microchips.

We have developed a novel cost-effective procedure, namely 'chemical nanoprinting', for oligonucleotide or cDNA chips manufacture. In this thermo-controlled process, the oligonucleotides, covalently attached to a highly loaded 'master-chip' through disulfide bonds, are chemically transferred to the acrylamide layer mounted on a 'print-chip'. It is demonstrated here that multiple identical print-chips can be produced from a single master-chip. This duplication process is a few hundreds of times faster than any existing methods and the speed of process and cost incurred are independent of the scale of the DNA chips.

DNA↗
PubMed1988

Liver volume measurements and three-dimensional display from MR images.

A method was investigated for measuring the volumes of human livers in vivo from magnetic resonance images and subsequently displaying these livers in three dimensions. Volumetric image sets of phantoms, healthy volunteers, and patients with cirrhotic livers were processed. Two image-processing approaches were compared for accuracy of liver measurements, intrasubject and interobserver variation, and speed of processing. Results indicated that both processing methods had a high degree of volume-measuring accuracy (within 8%), the interobserver measurements had a high coefficient of correlation (r = .9994), the intrasubject measurements had a low coefficient of variation (1.8%), and one method was four to five times faster than the other. The faster and easier of the two image-processing approaches provided satisfactory results for measuring liver volumes, but the slower approach provided more realistic-looking three-dimensional images of the liver.

Humans↗
PubMed2006

Effect of formulation and manufacturing parameters on process cheese food functionality--I. Trisodium citrate.

The objective of this research was to use a Rapid Visco Analyzer to study the effect of natural cheese age, trisodium citrate (TSC) concentration, and mixing speed on process cheese food (PCF) functionality. In this study 3 replicates of natural cheese were manufactured, and a portion of each cheese was subjected to 6 different PCF manufacturing treatments at 2, 4, 6, 12, and 18 wk of ripening. These treatments were factorial combinations of 3 levels of TSC (i.e., 2.0, 2.5, and 3.0%) and 2 mixing speeds during manufacture (450 and 1,050 rpm). Functional properties of the PCF evaluated included manufacturing properties [apparent viscosity after manufacture (VAM)], unmelted textural properties (firmness), melted cheese flow properties [hot apparent viscosity (HAV)], and cheese thickening during cooling [time at 5000 cP (T5)]. All 4 parameters (VAM, firmness, HAV, and T5) were significantly affected by natural cheese age and mixing speed, whereas VAM, HAV, and T5 were also significantly influenced by the amount of TSC. The VAM and firmness decreased as cheese age increased, whereas T5 values increased as cheese age increased. Similarly, VAM, HAV, and firmness values increased because of the increased mixing speed, whereas T5 values decreased. The age x mixing speed interaction was significant for VAM and firmness. The age x concentration of the TSC interaction term was significant for VAM, whereas the age x age x TSC concentration term was significant for HAV. The results demonstrate that natural cheese age, mixing speed during manufacture, and concentration of TSC have a significant impact on process cheese functionality.

Caseins↗
PubMed2004

Changes in neuropsychological functioning with progression of HIV-1 infection: results of an 8-year longitudinal investigation.

Despite the advent of more effective treatments for HIV-1 infection, cognitive impairment is still frequent and questions remain regarding which areas of impairment are more common in the different disease stages. This study investigated cognitive performance over an 8-year period of time in 59 HIV-1 seropositive (HIV-1+) men who were clinically asymptomatic at study entry, in comparison to a cohort of 55 HIV-1 seronegative (HIV-1-) men. Every 6 months we examined cognitive functioning in 5 domains-fine motor speed, attention, verbal memory, executive functioning, and speed of information processing. We found that patients with AIDS scored significantly worse on fine motor speed and speed of information processing than HIV-1- individuals and the HIV-1+ non-AIDS patients. In addition, the HIV-1+ non-AIDS patients performed more poorly than the HIV-1- group on speed of information processing. Depressive symptoms were also associated with diminished performance on measures of attention, executive functioning, and speed of information processing. Further research is needed to examine the effects of disease stage and depression on cognitive impairment in the era of new HIV treatments.

AIDS Dementia Complex↗
PubMed1996

Reaction time and variability 5 and 10 years after traumatic brain injury.

Improvement in performance can occur up to 10 years after traumatic brain injury (TBI). Few previous studies have examined the long-term effects of TBI on information processing. This study used reaction time (RT) tasks of increasing complexity with 10-year post-injury, 5-year post-injury, and control groups to assess any such effects. There were no significant group differences in mean RT; however, in the groups of persons with head injury only, response latency was related to age and to task demands. Older members of the groups of persons with head injury were slower than controls. The variability in performance was significantly higher in the 5-year post-injury group than in both the 10-year group and the control group. There were no significant differences among the groups in their ability to inhibit the processing of redundant information. There were no correlations between any dependent measure and severity of injury. Speed of processing is more sensitive to task complexity in individuals with head injury, but only when age at injury is considered. Most importantly, for rehabilitation purposes, recovery of consistency in performance can be expected more than 5 years after a TBI.

Adolescent↗
PubMed1997

Individual and sex differences in speed of handwriting among high school students.

A group of 153 high school students participated in a cursive handwriting task which required them to copy sentences as quickly as possible. The 78 girls performed significantly better than the 75 boys and a substantial range of speed for each sex was found. The results have implications for more demanding writing and composition processes. Handwriting speed has the potential to act as a limiting factor under some circumstances.

Adolescent↗
PubMed1991

Smooth steps to transition meetings.

New teams go through a maturation process that can, but often does not, lead to productivity. A properly conducted transition meeting can speed the process and ensure its success.

Group Processes↗
PubMed2001

Speed skills: measuring the visual speed analyzing properties of primate MT neurons.

Knowing the direction and speed of moving objects is often critical for survival. However, it is poorly understood how cortical neurons process the speed of image movement. Here we tested MT neurons using moving sine-wave gratings of different spatial and temporal frequencies, and mapped out the neurons' spatiotemporal frequency response profiles. The maps typically had oriented ridges of peak sensitivity as expected for speed-tuned neurons. The preferred speed estimate, derived from the orientation of the maps, corresponded well to the preferred speed when moving bars were presented. Thus, our data demonstrate that MT neurons are truly sensitive to the object speed. These findings indicate that MT is not only a key structure in the analysis of direction of motion and depth perception, but also in the analysis of object speed.

Action Potentials↗