SEARCH · PubMed Health

Results for “Task Shifting”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources

PubMed2003

Sequential effects in the lexical decision task: the role of the item frequency of the previous trial.

Two lexical decision experiments were conducted to determine whether there is a specific, localized influence of the item frequency of consecutive trials (i.e., first-order sequential effects) when the trials are not related to each other. Both low-frequency words and nonwords were influenced by the frequency of the precursor word (Experiment 1). In contrast, high-frequency words showed little sensitivity to the frequency of the precursor word (Experiment 2), although they showed longer reaction times for word trials preceded by a nonword trial. The presence of sequential effects in the lexical decision task suggests that participants shift their response criteria on a trial-by-trial basis.

Decision Making↗

PubMedDate not supplied

Hydrocarbon solvent exposure data: compilation and analysis of the literature.

An occupational exposure database for hydrocarbon solvent end-use applications was constructed from the published literature. The database provides exposure assessment information for such purposes as regulatory risk assessments, support of industry product stewardship initiatives, and identification of applications in which limited exposure data are available. It is quantitative, documented, and based on credible data. Approximately 350 articles containing quantitative hydrocarbon solvent exposure data were identified using a search of computer databases of published literature. Many articles did not report sufficient details of the exposure data for inclusion in the database (e.g., full-shift exposure or task-based exposure data). Others were excluded because only limited summary statistics were provided, which precluded statistical analysis of the data (e.g., arithmetic mean concentration presented, but no sample number). Following evaluation, 16,880 hydrocarbon solvent exposure measurements from 99 articles were entered into a database for analysis. Methods used to identify and evaluate published solvent exposure data are described along with more detailed analysis of worker exposure to hydrocarbon solvents in three major end-use applications: painting and coating, printing, and adhesives. Solvent exposures were evaluated against current ACGIH threshold limit values (TLVs) and trends were identified. Limited quantitative data are available prior to 1970. In general, reported hydrocarbon solvent exposures decreased fourfold from 1960 to 1998, were below the TLVs applicable to specific hydrocarbon solvents at the time, and on average have been below 40% of the TLV since 1980. The database already has proved valuable; however, the utility of published exposure data could be further improved if authors consistently reported essential data elements and supporting information.

Adhesives↗

PubMed2004

A survey of airborne isocyanate exposure in 13 Swedish polyurethane industries.

Exposure to isocyanates can be harmful to workers by causing different disorders of the airways. The main objectives of this study were to survey the personal 8 h time-weighted average exposure to isocyanates at 13 Swedish plants that handled either polyurethane, diisocyanates or both, including four types of manufacturing processes: moulding, continuous foaming, flame lamination and low or no heating processes. A total of 223 air samples were collected for 111 workers with personal air monitoring using a dry filter method with 1-(2-methoxyphenyl)piperazine (2MP) as derivatization reagent. A further 272 stationary samples were collected, using the 2MP method, a modified 2MP method and an impinger method using dibutylamine in toluene. With the applied strategy, a large number of workers were monitored and four industrial environments were compared regarding the isocyanate exposure. All workers were found to be exposed to isocyanates in the range 0.004-5.2 p.p.b. On average, the personal exposure levels in the different types of manufacturing processes were, in decreasing order: continuous foaming > flame lamination > moulding >> low or no heating processes. However, there were variations in exposure levels in plants with similar processes and also between different shifts performing the same tasks. Isocyanic acid, which could not be sampled by the 2MP method used for personal monitoring, was found by short-term stationary monitoring in levels up to 38 p.p.b. in the flame lamination plants.

Air Pollutants, Occupational↗

PubMed2000

Psychopathological syndromes of schizophrenia: evaluation of the dimensional structure of the positive and negative syndrome scale.

The Positive and Negative Syndrome Scale (PANSS) was originally designed as a rating system that provides balanced representation of positive and negative symptom features. Evidence from recent factor-analytic studies suggests that a five-dimensional solution appears to best fit the psychopathological data as assessed with the PANSS. To investigate the dimensional structure, we administered the PANSS to 253 inpatients with schizophrenia. In accordance with former studies, principal components analyses yielded five orthogonal dimensions: hostile excitement; negative, cognitive, and positive syndrome; and depression. When compared with questionnaires measuring subjective nonpsychotic experiences of schizophrenia, paranoid mood, and depression, the correlation pattern verifies the PANSS components. In addition, we investigated a subsample of 70 male patients with a Continuous Performance Test (CPT), a Span of Apprehension Task, and a Modality Shift Effect (MSE) paradigm; the CPT was significantly associated with the cognitive syndrome, and the MSE correlated with the negative syndrome.

Adult↗

PubMed1987

Aspects of tonic accommodation in emmetropia and late-onset myopia.

An objective infrared optometer was used to investigate the influence of cognitive demand on tonic accommodation (TA) for two groups of young emmetropes (N = 15) and late-onset myopes (N = 15). TA was measured under a passive condition and while subjects carried out a reverse counting task. The TA of myopes under the passive condition (mean = 0.81 D, SD = 0.46 D) was shown to have lower values than the TA of emmetropes (mean = 1.14 D, SD = 0.46 D). For the myopic group the counting task induced a positive shift in TA (mean = +0.35 D, SD = 0.31 D) that was significantly higher than that for the emmetropic group (mean = +0.07 D, SD = 0.27 D). The implications for theories of refractive error development are discussed.

Accommodation, Ocular↗

PubMed2003

Muscle fatigue and fatigue-related biomechanical changes during a cyclic lifting task.

STUDY DESIGN: Electromyographic and biomechanical methods were utilized to investigate correlations between indexes of localized muscle fatigue and changes in the kinematics and kinetics of motion during a cyclic lifting task. SUMMARY OF BACKGROUND DATA: Recent advances in time-frequency analysis procedures for electromyographicic signal processing provide a new way of studying localized muscle fatigue during dynamic contractions. These methods provide a means to investigate fatigue-related functional impairments in patients with low back pain. OBJECTIVES: To study the relationship between localized muscle fatigue and the biomechanics of lifting and lowering a weighted box. Fatigue-related changes in the electromyographicic signal of trunk and limb muscles were evaluated and compared to kinematic and kinetic measures in order to determine whether lifting strategy is modified with fatigue. METHODS: A total of 14 healthy male subjects (26 +/- 5 years) cyclically lifted and lowered a 13 kg box (12 lifts/min) for 4.5 minutes. A 5-second static maximum lifting task was included immediately before and after the cyclic lifting task to measure changes in lifting strength and static electromyographicic fatigue indexes. Electromyographic signals from 14 muscle sites (including paravertebral and limb muscles) were measured. Changes in the electromyographicic Instantaneous Median Frequency, a fatigue index, were computed using time-frequency analysis methods. This index was compared with more standardized measures of fatigue, such as those based on electromyographicic median frequency acquired during a static trunk extension test, subjective fatigue measures, and maximal static lifting strength. Biomechanical measures were gathered using a motion analysis system to study kinematic and kinetic changes during the lifting task. RESULTS: During the cyclic lifting task, the electromyographic Instantaneous Median Frequency significantly decreased over time in the paravertebral muscles, but not in the limb muscles. Paravertebral electromyographicic Instantaneous Median Frequency changes were consistent with self-reports of fatigue as well as decreases in trunk extension strength. The magnitude of muscle-specific changes in electromyographicic Instantaneous Median Frequency was not significantly correlated with electromyographicic median frequency changes from the static trunk extension task. The load of the box relative to the maximal static lifting strength significantly affected the electromyographicic Instantaneous Median Frequency changes of paravertebral back muscles. Significant changes with fatigue during the task were found in the angular displacements at the knee, hip, trunk, and elbow. These biomechanical changes were associated with increased peak torque and forces at the L4-L5 vertebral segment. CONCLUSIONS: Our results demonstrate correlation between localized muscle fatigue and biomechanical adaptations that occur during a cyclic lifting task. This new technique may provide researchers and clinicians with a means to investigate fatigue-related effects of repetitive work tasks or assessment procedures that might be useful in improving education, lifting ergonomy, and back school programs. Although both the dynamic and static tasks resulted in spectral shifts in the electromyographicic data, the fact that these methods led to different muscle-specific findings indicates that they should not be considered as equivalent assessment procedures.

Adult↗

PubMed2004

The effects of sleep debt and monotonous work on sleepiness and performance during a 12-h dayshift.

The study examined the effects of the amount of preceding sleep and work pace on sleepiness and cognitive performance during a 12-h dayshift. Twelve process operators (aged 28-56 years) completed a study with four single 12-h dayshifts and preceding night sleep in the laboratory. A simulated distillation process served as a work task. The 12-h shifts differed from each other in terms of the amount of preceding night sleep (23:00-06:30 hours or 2:30-6:30 hours) and work pace (slow or fast). All shifts contained four work simulation sessions of 1.5 h, and each of them included a 15-min alarm session. Cognitive performance was also measured with a 10-choice reaction time test and a mental subtraction test. Objective sleepiness was measured with a continuous electroencephalography/electro-oculography (EEG/EOG) recording during the work periods and with a sleep latency test. Subjective sleepiness at work was measured with the Karolinska Sleepiness Scale. Sleep debt increased the proportion of EEG/EOG-defined and subjective sleepiness at work, but did not impair work or test performance. The fatiguing effect of monotonous work as indicated by EEG/EOG-defined sleepiness was comparable with the effect of sleep debt. The alarm epochs in the middle of monotonous work temporarily decreased EEG/EOG-defined sleepiness. Sleep debt or monotonous work did not have a significant effect on the results of the sleep latency test. None of the sleepiness or performance measures indicated the impairment of a subject's functional capacity at the end of the 12-h shift. Our results suggest that monotonous work is at least as harmful as moderate sleep debt for alertness at work. The results support the view that the last hours of a single 12-h dayshift with frequent pauses are not associated with an increase in sleepiness or performance errors.

Adult↗

PubMed1997

Neural correlates of motor memory consolidation.

Computational studies suggest that acquisition of a motor skill involves learning an internal model of the dynamics of the task, which enables the brain to predict and compensate for mechanical behavior. During the hours that follow completion of practice, representation of the internal model gradually changes, becoming less fragile with respect to behavioral interference. Here, functional imaging of the brain demonstrates that within 6 hours after completion of practice, while performance remains unchanged, the brain engages new regions to perform the task; there is a shift from prefrontal regions of the cortex to the premotor, posterior parietal, and cerebellar cortex structures. This shift is specific to recall of an established motor skill and suggests that with the passage of time, there is a change in the neural representation of the internal model and that this change may underlie its increased functional stability.

Adult↗

PubMed1983

Shadows of thought: shifting lateralization of human brain electrical patterns during brief visuomotor task.

Dynamic spatial patterns of correlation of electrical potentials recorded from the human brain were shown in diagrams generated by mathematical pattern recognition. The patterns for "move" and "no-move" variants of a brief visuospatial task were compared. In the interval spanning the P300 peak of the evoked potential, higher correlations of the right parietal electrode with occipital and central electrodes distinguished the no-move task from the move task. In the next interval, spanning the readiness potential in the move task, higher correlations of the left central electrode with occipital and frontal electrodes characterized the move task. These results conform to neuropsychological expectations of localized processing and their temporal sequence. The rapid change in the side and site of localized processes may account for conflicting reports of lateralization in studies which lacked adequate spatial and temporal resolution.

Adult↗

PubMed1999

Isodirectional tuning of adjacent interneurons and pyramidal cells during working memory: evidence for microcolumnar organization in PFC.

Studies on the cellular mechanisms of working memory demonstrated that neurons in dorsolateral prefrontal cortex (dPFC) exhibit directionally tuned activity during an oculomotor delayed response. To determine the particular contributions of pyramidal cells and interneurons to spatial tuning in dPFC, we examined both individually and in pairs the tuning properties of regular-spiking (RS) and fast-spiking (FS) units that represent putative pyramidal cells and interneurons, respectively. Our main finding is that FS units possess spatially tuned sensory, motor, and delay activity (i. e., "memory fields") similar to those found in RS units. Furthermore, when recorded simultaneously at the same site, the majority of neighboring neurons, whether FS or RS, displayed isodirectional tuning, i.e., they shared very similar tuning angles for the sensory and delay phases of the task. As the trial entered the response phase of the task, many FS units shifted their direction of tuning and became cross-directional to adjacent RS units by the end of the trial. These results establish that a large part of inhibition in prefrontal cortex is spatially oriented rather than being untuned and simply regulating the threshold response of pyramidal cell output. Moreover, the isodirectional tuning between adjacent neurons supports a functional microcolumnar organization in dPFC for spatial memory fields similar to that found in other areas of cortex for sensory receptive fields.

Action Potentials↗

PubMed2004

Functional magnetic resonance imaging before and after aphasia therapy: shifts in hemodynamic time to peak during an overt language task.

BACKGROUND AND PURPOSE: Comparing the temporal characteristics of hemodynamic responses in activated cortical regions of aphasic patients before and after therapy would provide insight into the relationship between improved task performance and changes in blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signal. This study investigated differences in the time to peak (TTP) of hemodynamic responses in activated regions of interest (ROIs), before and after therapy, and related them to changes in task performance. METHODS: Three aphasic patients and 3 controls overtly generated a single exemplar in response to a category. For the patients, TTP of hemodynamic responses in selected ROIs was compared before and after language therapy. The timing differences between auditory cues and verbal responses were compared with TTP differences between auditory and motor cortices. RESULTS: The selected ROIs were significantly activated in both aphasic patients and controls during overt word generation. In the aphasic patients, both the timing difference from auditory cues to verbal responses and the TTP difference between auditory and motor cortices decreased after rehabilitation, becoming similar to the values found in controls. CONCLUSIONS: Findings indicate that (1) rehabilitation increased the speed of word-finding processes; (2) TTP analysis was sensitive to this functional change and can be used to represent improvement in behavior; and (3) it is important to monitor the behavioral performance that might correlate with the temporal pattern of the hemodynamic response.

Acoustic Stimulation↗

PubMed2006

Impact of shift work on the health and safety of nurses and patients.

Shift work generally is defined as work hours that are scheduled outside of daylight. Shift work disrupts the synchronous relationship between the body's internal clock and the environment. The disruption often results in problems such as sleep disturbances, increased accidents and injuries, and social isolation. Physiologic effects include changes in rhythms of core temperature, various hormonal levels, immune functioning, and activity-rest cycles. Adaptation to shift work is promoted by reentrainment of the internally regulated functions and adjustment of activity-rest and social patterns. Nurses working various shifts can improve shift-work tolerance when they understand and adopt counter measures to reduce the feelings of jet lag. By learning how to adjust internal rhythms to the same phase as working time, nurses can improve daytime sleep and family functioning and reduce sleepiness and work-related errors. Modifying external factors such as the direction of the rotation pattern, the number of consecutive night shifts worked, and food and beverage intake patterns can help to reduce the negative health effects of shift work. Nurses can adopt counter measures such as power napping, eliminating overtime on 12-hour shifts, and completing challenging tasks before 4 am to reduce patient care errors.

Adaptation, Physiological↗

PubMed2002

Sustained attention deficit in bipolar disorder.

BACKGROUND: Recovery in bipolar disorder is central to its definition but is rarely complete. Previous work has suggested that neuropsychological impairment persists during the euthymic state but has been confounded partly by mild affective symptoms in remitted patients. AIMS: To characterise neuropsychological functioning in the euthymic phase of bipolar disorder with an emphasis on tasks of executive functioning. METHOD: Thirty euthymic patients with bipolar disorder were compared with thirty healthy controls on neuropsychological tasks differentially sensitive to damage within prefrontal cortex. RESULTS: Bipolar I patients were impaired on tasks of attentional set shifting, verbal memory and sustained attention. Only sustained attention deficit survived controlling for mild affective symptoms. This deficit was related to progression of illness, but was none the less present in a subgroup of patients near illness onset. CONCLUSIONS: Sustained attention deficit may represent a neuropsychological vulnerability marker for bipolar disorder, providing a focus for further understanding of the phenotype and analysis of the neuronal networks involved.

Adolescent↗

PubMed2001

Tracking of spatial information in narratives.

Three experiments were conducted to investigate the process by which location information in narratives is represented in memory and the nature of the resulting memory representation. In Experiments 1 and 2, the results of a recognition task demonstrated that location shifts led to an immediate decrease in the accessibility in memory of protagonists' former locations. In Experiment 3, regardless of the amount of backgrounding after the last mention of the critical location ("the forest"), reference to an implied, location-typical entity ("the trees") was read equally fast as long as the protagonist remained in that location. In contrast to previous findings, we conclude that when location information is salient in a narrative it is included in readers' situation models, being updated immediately and remaining highly accessible even several sentences after it was last mentioned.

Cognition↗

PubMedDate not supplied

The myth of the top management team.

Companies all across the economic spectrum are making use of teams. They go by a variety of names and can be found at all levels. In fact, you are likely to find the group at the very top of an organization professing to be a team. But even in the best of companies, a so-called top team seldom functions as a real team. Real teams must follow a well-defined discipline to achieve their performance potential. And performance is the key issue--not the fostering of "team values" such as empowerment, sensitivity, or involvement. In recent years, the focus on performance was lost in many companies. Even today, CEOs and senior executives often see few gains in performance from their attempts to become more teamlike. Nevertheless, a team effort at the top can be essential to capturing the highest performance results possible--when the conditions are right. Good leadership requires differentiating between team and nonteam opportunities, and then acting accordingly. Three litmus tests must be passed for a team at the top to be effective. First, the team must shape collective work-products--these are tangible performance results that the group can achieve working together that surpass what the team members could have achieved working on their own. Second, the leadership role must shift, depending on the task at hand. And third, the team's members must be mutually accountable for the group's results. When these criteria can be met, senior executives should come together to achieve real team performance. When the criteria cannot be met, they should rely on the individual leadership skills that they have honed over the years.

Administrative Personnel↗

PubMed2000

Visuospatial attention and motor reaction in children: an electrophysiological study of the "Posner" paradigm.

To assess the processing stages involved in attention shifting and response selection tasks in children, we recorded event-related potentials (ERPs) and performance measures during a variant of the Posner paradigm. Subjects responded to visual targets, either preceded by a spatial cue (valid = same side; invalid = opposite side) or presented uncued. Valid targets evoked high-amplitude P1 responses, single-peaked P3s, and the shortest reaction times (RTs). Invalidity cued stimuli evoked delayed RTs, resulting in part from incorrectly oriented attention (decreased P1) leading to delayed target processing (belated N2-P3). Invalid targets also evoked a positive slow wave attributed to prolonged response selection due to cue/target incompatibility. Uncued stimuli elicited the longest RTs, unexplained by deficits in target detection or response selection, which likely resulted from a deficit in motor preparation due to the lack of warning signal. This method may be applied in clinical settings to disentangle selective processing deficits in target detection, response selection, or motor preparation stages.

Adolescent↗

PubMed2001

[Waiting times in specialist medical care].

Waiting times in specialist medical care are difficult to reduce owing to the fast-growing demand with supply lagging behind. These waiting times were the subject of a conference of this Journal, where experts from different backgrounds assessed the problems and discussed promising ways of coping with them at micro, meso and macro level. In the first category, a system developed in Leiden University Medical Centre was presented that provides insight into the expected waiting time per disease category, elucidates the bottlenecks in practice and supports the quality of care and the planning of patient flows. At the meso level, the discussion addressed how the differences within and between institutions and within and between regions may be reduced; this may be done, for instance, by better spread of the work load. This offers a better contribution to a structural solution than extra-regular initiatives. The conference finally discussed the importance of the current shift of important (control) tasks from the government to insurers. Those present expected that stimulation of regional initiatives of hospitals and health insurers by means of more money and latitude, allocated by the government and under its control (inspection), offers the best opportunities to shortening of the waiting lists and improvement of the quality of care.

Health Services Accessibility↗

PubMed2003

Perceptual attentional set-shifting is impaired in rats with neurotoxic lesions of posterior parietal cortex.

The posterior parietal cortex (PPC) is believed to be involved in the representation of spatial information, including spatial attentional processing. Because the PPC is extensively interconnected with frontal cortical regions involved in attention and executive function, we sought to determine whether PPC was involved in nonspatial attentional processes such as those of the frontal areas to which it projects. Lesions of the medial frontal cortex (in rats) or lateral prefrontal cortex (in nonhuman primates) impair the ability to shift attention from one perceptual dimension of a stimulus to another (referred to as an extradimensional shift). Rats with neurotoxic lesions of the PPC tested in an attentional set-shifting paradigm demonstrated a pattern of impairment identical to that of rats with medial frontal cortex lesions: they were selectively impaired on the extradimensional shift phase of the task. Performance in other phases of the task was indistinguishable from that of control rats, including the ability to reverse a previously learned discrimination. These findings are consistent with models that assign the PPC a prominent role in cortical attentional processing networks, as well as a role for the PPC in processing information about expectancy and surprise. They also suggest, importantly, that the interaction between the PPC and the frontal cortex is not limited to spatial attentional processing.

Animals↗