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At least 253 records · Page 14Linked to original sources

PubMed1999

Neurological soft signs in adolescents with poor performance on the continous performance test: markers of liability for schizophrenia spectrum disorders?

There is much evidence that neurological soft signs (NSS) are highly prevalent in both adults and children with schizophrenia. In addition, they have been detected as early precursors of a schizophrenic outcome in at-risk subjects. Such findings point to the possible value of NSS as neurointegrative markers in schizophrenia which has been hypothesized to be a neurodevelopmental disease. In our study we used a biobehavioral criterion to select the 'at-risk' group, a sustained attentional deficit as measured by the continuous performance test (CPT). We compared 140 normal adolescents with 162 'CPT-linked vulnerable' adolescents (index subjects) on a battery for the assessment of NSS (including laterality), IQ, frontal lobe function and schizotypy. An association was found between NSS and attentional deficit. Furthermore, index subjects with NSS were characterized by lower IQ scores, poorer performance on frontal lobe tests and greater problems with social interaction. There was also a trend for an association between male sex and both left-handedness and NSS.

Adolescent↗

PubMed2002

The moderating influence of job performance dimensions on convergence of supervisory and peer ratings of job performance: unconfounding construct-level convergence and rating difficulty.

Meta-analysis was used to cumulate the correlations between supervisor and peer ratings for different dimensions of job performance. The general pattern in the data suggested that raters from the same organizational level disagree as much as raters from different levels. Methods were used to separate the effects of rating difficulty and lack of construct-level convergence on the correlation between supervisor and peer ratings. The authors found complete construct-level convergence for ratings of overall job performance, productivity, effort, job knowledge, quality, and leadership but not for ratings of administrative competence, interpersonal competence, and compliance or acceptance of authority. Higher rating difficulty was more strongly associated with lower mean observed peer-supervisor correlations than were construct-level disagreements between peers and supervisors. Implications for research and practice are discussed.

Adult↗

PubMed2003

Categorical-relational and order-relational information in memory for subject-performed and experimenter-performed actions.

Memory for self-performed tasks (SPTs) is better than memory for experimenter-performed tasks (EPTs). In short unrelated lists of actions this effect occurs if the encoding condition is manipulated within subjects. In a between-subjects design, the enactment effect disappears (J. Engelkamp & D. Dehn, 2000; J. Engelkamp & H. D. Zimmer, 1997). These findings were explained by the item-order hypothesis, which claims that encoding order information depends on the type of encoding and design. The authors demonstrate that this differential encoding of order information in EPTs and SPTs is not effective in free recall if categorized lists are used. The use of categorized lists makes the interaction of type of encoding and design in free recall of short lists disappear, and the enactment effect reappears independent of the type of design.

Humans↗

PubMed1996

What determines continuous performance task performance?

The Continuous Performance Task (CPT) is widely used as an indicator of cognitive dysfunction in schizophrenia. It is still unclear, however, exactly what this test measures. We examined the contribution of motor speed, reaction time measures, mental effort, and level of psychopathology to the performance on a double-stimulus CPT. This study included schizophrenia patient groups, depressive patient groups, and patient and normal control groups. Subjects were retested twice: once after 1 week and again at 3 months. In patients with schizophrenia or depression, the sensitivity measure (d') was strongly and consistently associated with motor speed and with the standard deviation of reaction times (response variability) to target stimuli. The association with response variability was also found at followup tests in the control groups. We conclude that in patients with schizophrenia or depression, the sensitivity measure of a double-stimulus CPT is associated with cognitive mechanisms that determine motor proficiency and response variability.

Adult↗

PubMed1995

Performance study involving a force-reflecting joystick for spastic individuals performing two types of tracking tasks.

10 upper-extremity spastic subjects and 10 normal subjects were studied with a force-reflecting joystick in the performance of a continuous time-tracking task as well as an acquisition task termed, "Fitts' Law." Certain force-reflection paradigms, in a spatial sense, allowed the spastic subjects to obtain performance proficiency near levels of the normal subjects as measured by a capacity metric.

Hand Strength↗

PubMed1995

Effects of batting performance feedback on motivational factors and batting performance in youth baseball.

The effects of batting feedback on motivational factors and batting of young baseball players were investigated. Hypotheses were that, compared to participants receiving feedback or no feedback on their batting average, those receiving contact average would exhibit (a) a greater increase in batting efficacy, (b) more enjoyment, satisfaction, and persistence, and (c) superior batting performance. Participants were 78 children from nine teams. Although analyses did not support the hypotheses, performance-to-efficacy correlations as well as other data provided tentative evidence for the premise that contact average may be more appropriate feedback for young players because (compared to batting average) it is less ambiguous and is based on a more realistic definition of success. Limitations and implications for coaches were discussed.

Baseball↗

PubMed2001

Dynamic strength capabilities of small-stature females to perform high-performance flight tasks.

BACKGROUND: Naval Air Warfare Center Aircraft Division investigated the abilities of small-stature females (< or = 120 lb.) to fly under G-stress using the Dynamic Flight Simulator (DFS) and its tactical fight/attack cockpit, displays and controls. The objective was to determine if these individuals possess sufficient upper-body muscular endurance to perform tasks required during fighter-pilot training, aerial combat maneuvers, and failure modes. METHODS: Five female subjects (four small-stature and one medium) participated. DFS tasks featured bombing runs, surface-to-air missile (SAM) avoidance, and single engine failure. Muscular exertion and fatigue (arm, shoulder, neck) were assessed using electromyography. RESULTS: During the most physically taxing simulation (SAM avoidance), flight performance did not significantly degrade over time. No statistically significant increase in muscular fatigue was found during the bombing simulation, though there was some evidence of degraded fine muscle control. Evidence of flexor and extensor muscular fatigue was associated with the single-engine-failure simulation. CONCLUSIONS: Within the scope of these tests, small-stature individuals demonstrated the strength and endurance to safely fly physically strenuous missions. However, a larger subject sample is necessary to increase the statistical power of the results.

Adult↗

PubMed2003

Study on performance following Key Performance Indicators for trauma care: Khon Kaen Hospital 2000.

This study was conducted in 2000-2001 in order to improve the quality of trauma care by establishing the Key Performance Indicators (KPIs) as a guideline in providing trauma care service and to study the personnel's performance following 27 indexes of KPIs for trauma care in Khon Kaen Hospital. After the implementation of the KPIs by the method of participatory action research (PAR), the trauma preventable death rate was decreased to 1.3 per cent which was statistically different from the preventable death rate in 1997 (2.0%).

Emergency Medical Services↗

PubMed1987

A perspective on human performance as the limiting factor in aircraft performance.

The popular notion appears to be growing that the human is the limiting factor in aircraft performance. Proponents cite recent instances of pilot loss of consciousness during maneuvers. The aerospace medicine perspective differs, seeing the aircraft not as a vehicle in which to make hard turns, but as a mission-directed weapon system for which the pilot is the enabling factor. Various "human limiting factors" are described among requirements staffs, developers, researchers, trainers, and operators. A plea is made to pursue available avenues to improve manned weapon system performance and to see even our most sophisticated weapons as human instruments.

Aerospace Medicine↗

PubMed2003

Separation of capsular polysaccharide K4 and defructosylated K4 derived disaccharides by high-performance capillary electrophoresis and high-performance liquid chromatography.

A rapid, highly sensitive and reproducible high-performance capillary electrophoresis (HPCE) method (electrokinetic chromatography with sodium dodecyl sulfate) is described for the determination of disaccharides present in the polysaccharide from the uropathogenic Escherichia coli K4 bacteria (05:K4:H4) and its defructosylated product. Following chondroitinase digestion of K4 and its derivative, the two disaccharides, DeltaHexAFrc-GalNAc for K4 and deltaHexA-GalNAc for defructosylated K4, are separated and readily determined within 20 min on an uncoated fused-silica capillary using normal polarity at 20 kV and detection at 230 nm. Comparison was made by separation of these two disaccharides in isocratic strong-anion exchange HPLC. A linear relationship was found for the two unsaturated disaccharides over a wide range of concentrations, from approximately 0.5 to 5 micro g for high-performance liquid chromatography (HPLC) and from approximately 0.06 to 0.3 micro g for HPCE. The HPCE separation produced a greater detection sensitivity (about 10 times greater) than HPLC. The described methods were used to evaluate the defructosylation process of K4 under drastic acid conditions. Good correspondence was found for the amount of unsaturated disaccharides for the two techniques.

Bacterial Capsules↗

PubMedDate not supplied

Performance indicators and performance assessment in the UK National Health Service: implications for management and planning.

Throughout the Western world policy makers are seeking to control the use of health care resources. Often the primary motive for these policies is to control or the total level of public expenditure on health care. One manifestation of such policies in the USA is the use of diagnostic related groups (DRGs), and this instrument is now being adopted in Europe (for example, in France as from January 1986). In Britain, as similar management tool is that of performance indicators, which are basically measures of input and activity. In this article it is argued that management responses to these measures may not lead to greater efficiency in resource utilization. Whilst the use of input and process measures to control resource allocation are better than no controls at all, the achievement of efficiency requires that such measures are supplemented with the assessment of outcomes and analyses of input-output relationships. Such supplementation, for example by using quality-adjusted life years (QALYs), is urgently required if policy makers are not to become disenchanted with the usefulness of existing performance indicators.

Efficiency↗

PubMed1983

Comparative assays for doxepin and desmethyldoxepin using high-performance liquid chromatography and high-performance thin-layer chromatography.

Two chromatographic methods, high-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC) were compared for sensitivity and reproducibility in the analysis of the tricyclic antidepressant doxepin and its metabolite, desmethyldoxepin, in plasma. The HPLC procedure yielded a better reproducibility, as reflected by the coefficient of variation, and a higher sensitivity, as reflected by the minimum detectable quantity. The application of these methods for therapeutic and subtherapeutic monitoring of plasma levels of the drug is described.

Animals↗

PubMed1992

High-performance frontal analysis-high-performance liquid chromatographic system for stereoselective determination of unbound ketoprofen enantiomers in plasma after direct sample injection.

An on-line, high-performance frontal analysis (HPFA)-high-performance liquid chromatographic system was developed for the enantioselective determination of a low level of unbound ketoprofen (KP) that is in equilibrium with KP that is bound to protein. The system consists of three subsystems (HPFA system, preconcentration system, and chiral separation system) connected in series in the stated order via column-switching valves. When either a 300-microL portion of buffer solution containing 300 or 550 microM human serum albumin and 100 or 300 microM racemic KP or a 300-microL portion of human plasma containing 12.5-100 microM racemic KP was directly injected onto the HPFA column with the mobile phase at a low flow rate, KP was separated from proteins and eluted as a zonal peak with a plateau. The KP concentration in the eluant of the plateau region was the same as the unbound-KP concentration that was in equilibrium with protein-bound KP in the initial sample solution. A 1-mL portion of the eluant of the plateau region was switched to the preconcentration system, where KP was adsorbed and condensed on an octadecylsilyl silica (ODS) column. The adsorbed KP was eluted out of the ODS column and transferred to the chiral separation system, via another switching valve, where the enantiomers of unbound KP were separated and determined. The results agree well with those obtained by the conventional ultrafiltration method.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, High Pressure Liquid↗

PubMed2006

Advantages of ultra performance liquid chromatography over high-performance liquid chromatography: comparison of different analytical approaches during analysis of diclofenac gel.

Miniaturization embracing instrumentation, column particle size, and column dimensions is one of the major current trends in separation techniques. This leads to shortening of analysis time and great savings in solvent consumption. Ultra performance liquid chromatography (UPLC) is one of the new developments in liquid chromatography. An ultra-high pressure system allows using of small particle-packed columns with small diameter, which has a positive effect on both system efficiency and analysis time. An analytical method for determination of the active substance diclofenac, the degradation product 1-(2,6-dichlorphenyl)-2-indolinone, and the preservatives methylparaben and propylparaben was used for testing and comparing LC systems. Various octadecylsilica-based analytical columns were examined. Acquity UPLC BEH C18 (2.1 x 50 mm, 1.7 microm) and (2.1 x 100 mm, 1.7 microm) were tested for UPLC. The following analytical columns were used in a test for HPLC: Purospher RP 18e (125 x 4.0 mm, 5 microm), Zorbax Eclipse XDB C18 (75 x 4.6 mm, 3.5 microm), Zorbax Eclipse SB C18 (50 x 4.6 mm, 1.8 microm), as was a monolithic column (Chromolith Performance RP-18e (100 x 4.6 mm). Results of a System Suitability Test (SST) were calculated and compared for each chromatographic peak. System efficiency and analysis duration were compared with regard to solvent consumption and system maintenance

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2003

Determination of Tripamide in human urine by high-performance liquid chromatography and high-performance liquid chromatography/electrospray ionization tandem mass spectrometry.

Tripamide is a drug widely used in clinical practice for the treatment of hypertension and edema. This work evaluated a screening method for Tripamide and its urinary metabolites in human urine, using high-performance liquid chromatography diode-array detection (HPLC/DAD). Identification of these metabolites was investigated by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) after dosing with 15 mg Tripamide. Acid hydrolysis showed that Tripamide is conjugated in the body. Two suspected metabolites were detected by HPLC/DAD. HPLC/ESI-MS/MS analysis suggested that these metabolites were probably hydroxylated together with loss of the -NH(2) group and dehydrogenation. These results will be useful in confirmation methods for Tripamide in doping control.

Adult↗

PubMed1999

Fluency versus conscious recollection in category-production performance: the performance of schizophrenic patients.

The purpose of this study was to investigate the relative contribution in schizophrenics of automatic processes (fluency) and conscious processes (conscious recollection) for the control of preencoded material in category production tasks. In one condition (Exclusion condition), subjects were told specifically not to produce previously presented words during the category-production task. This condition was compared with a standard category-production task in which subjects were told to produce the six first words that came to mind for a semantic category (Inclusion condition). In the inclusion condition, the effects of conscious control and automatic processes operated in the same direction, whereas in the exclusion condition automatic influences and conscious control were opposed. A recognition task followed the category-production tasks. Since the exclusion condition required conscious control of encoded items, we hypothesized that schizophrenic patients would be less able than control subjects to avoid producing study list items. These results indicated that schizophrenics' performance differed from these of control subjects in the exclusion condition but not in inclusion condition. Recognition performance was similar in both the schizophrenic and the control groups. These results suggest a defective conscious control in schizophrenic patients and confirm the data from the literature on explicit memory in these patients.

Female↗

PubMed1999

Acute ethanol administration impairs spatial performance while facilitating nonspatial performance in rats.

Acute ethanol administration produces learning and memory impairments similar to those found following lesions to the hippocampal system in rats. For example, both ethanol and hippocampal lesions impair performance on spatial learning and memory tasks while sparing performance on many nonspatial learning and memory tasks. Lesions to the hippocampal system can also alter the nature of the information that the animal uses to guide its behavior, from using spatial information to using individual cues. In the present experiment, rats were trained, while sober, to navigate on an eight-arm radial arm maze to a specific arm for food reward. During training, the rewarded arm was always in the same specific location and contained well-defined cues. After the rat learned the task, a memory test was conducted under different doses of ethanol (0.0 g/kg [saline control], 1.0, 1.5, or 2.0 g/kg, intraperitoneal). On the test day the maze was rotated so that the cued arm was 90 degrees to the right of its original position. During testing, intact rats showed a significant bias to approach the place where they had been previously rewarded, even though the cue was no longer located there. Acute ethanol administration dose dependently reduced approaches to the rewarded place. However, ethanol administration did not result in increases in random choices; rather, it resulted in a dose-dependent increase in approaches to the cued arm, now in a new location. These results extend previous research showing that acute ethanol administration and lesions to the hippocampal system produce similar effects on learning and memory in rats.

Animals↗

PubMed1989

Central station data displays: an experimental evaluation of observer performance. Part 2: Factors affecting performance, and a comparison of analogue and digital data.

16 experienced ICU nurses monitored simulated central station VDU displays for the occurrence of ectopic beats and for signs of deterioration in general cardiovascular status. Each period of monitoring lasted for 1 h, and on separate occasions each nurse monitored 1, 2, 4 or 6 displays simultaneously. For primary clinical tasks, the data showed that the nurses' performance improved with each test. The identification of ventricular ectopic beats (VEBs) improved within the 1 h of each test except when 6 screens were being viewed simultaneously, with a similar result for the identification of deterioration of cardiovascular status. The nurses showed a marked preference for analogue signals over digits for the identification of VEBs. The highest priority clinical task was the identification of deteriorating cardiovascular status. When this task was performed efficiently less attention was given to minor tasks, and the nurse rated herself as very tired.

Attitude of Health Personnel↗