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PubMed1994

Effect of skill on visual laterality: now you see it--now you don't.

Clancy and Hoyer (1993) have recently investigated the effects of domain-specific expertise and hemispheric asymmetry on detecting featural differences in visual patterns. Based on the pattern of reaction time results, they concluded that there is a left-hemisphere advantage for making difficult, domain-relevant visual discriminations in skilled experts but not in unskilled control subjects. However, response accuracy data from the same experiment contradict their conclusions about the relationship of skill to the pattern of hemispheric asymmetry and favor an alternative interpretation in terms of the specific aspects of visual information needed to make different types of discrimination.

Attention↗

PubMed1996

Reasoning from memory: a lifespan inquiry into the necessity of remembering when reasoning about class inclusion.

In the current experiment, we evaluated the relationship between reasoning and remembering across the lifespan (10-, 13-, 15-, 23-, and 67-year-olds) using color and number class-inclusion tasks. Subjects made judgments when memory load or information load was either high or low. Reading latency, choice latency, and choice accuracy data were collected and analyzed using formal models that partitioned memory and reasoning as well as type of reasoning strategy. The results showed that: (1) study skills, as indexed by reading latency, were sophisticated across the lifespan; (2) the difference between color and number choice latencies increased with age; (3) reasonably consistent effects were obtained as a function of increasing memory load, with the quality of both reasoning and remembering being adversely affected; (4) different effects were obtained at each age as a function of increasing information load; and (5) the major developmental trend across the lifespan was a tradeoff between class-inclusion and subclass-subclass forms of reasoning. A number of extant theoretical approaches were discussed, none of which were able to account for variations in class-inclusion performance across the lifespan. What was clear, however, was that memory-reasoning dependencies must be incorporated into any comprehensive theory of cognitive development across the lifespan.

Adolescent↗

PubMed1994

Evaluation of an automated spectrophotometric assay for the determination of total sialic acid in canine serum.

This study validates an automated enzymatic assay using the Cobas Fara (Roche) centrifugal analyser, which offers a reliable measurement of the total sialic acid concentration in canine serum as assessed by evaluating the precision and accuracy. Data are presented on the biological variation in the total serum sialic acid concentration. Measurements of total serum sialic acid concentration appear to be useful in distinguishing dogs with neoplastic disorders from clinically healthy dogs.

Analysis of Variance↗

PubMed2004

No evidence of a lower visual field specialization for visuomotor control.

The lower visual field (loVF) has been hypothesized to demonstrate specialization for skilled, visually guided action. According to Danckert and Goodale, this visual field asymmetry indirectly suggests that the loVF has privileged connections to visuomotor networks within the dorsal visual pathway. Here we attempted to replicate the loVF advantage during the execution of a discrete aiming movement to targets of various widths (index of difficulty ranging from 1.5 to 5 bits). In addition, we employed trials in which vision of the target object was available or unavailable during the reaching movement to determine whether or not the purported visual field asymmetry reflects enhanced central planning (i.e., feedforward) or online control (i.e., feedback) processes. Reaching trajectories were examined for indicators of online amendments, and movement times and endpoint characteristics were examined to quantify possible visual field asymmetries in relative speed/accuracy trade-offs. In terms of reaching kinematics, it was found that vision of the target during the reaching movement resulted in greater online control of the reaching trajectory; however, no significant main effects or interactions involving visual field were observed. In other words, fixating in the upper or the lower region of peripersonal space did not influence the nature of reaching control (i.e., feedback vs. feedforward). Most importantly, our movement time and endpoint accuracy data elicited a robust speed/accuracy trade-off in both upper and lower regions of working space. Thus, and contrary to previous findings (such as those reported by Danckert and Goodale), the indices of difficulty coupled with the discrete aiming task used here did not elicit a lower visual field advantage for visually guided action.

Adult↗

PubMed2006

Cost accounting to determine prices: how well do prices reflect costs in the German DRG-system?

Germany has recently introduced a system of Diagnosis Related Groups (DRGs) to engender more appropriate resource allocation. The following article describes the German DRG-system and the methodologies used to determine prices. It analyses the extent to which prices, or calculated cost weights, reflect the actual costs incurred by hospitals for their respective services. We reveal that a "compression" of DRG cost weights occurs, and that the data sample used to calculate cost weights is lacking in terms of its representativeness. Although cost data accuracy has improved over the last few years there are still a number of challenges that need to be addressed.

Accounting↗

PubMed1986

Fine needle aspiration biopsy. Has its time come?

Fine needle aspiration biopsy has been undergoing a revival in the United States, but a recent survey showed that many clinicians were uncertain how to utilize this test. The scope of fine needle aspiration biopsy as practiced at the University of California, San Francisco, and the San Francisco General Hospital is described. The relevant accuracy data available in the world literature on this procedure are also reviewed.

Abdominal Neoplasms↗

PubMed1990

Event-related brain potentials as indices of information extraction and response priming.

Measures of overt response and of the event-related brain potential (ERP) were used to investigate the processing of a priming stimulus varying in its information content. Subjects were shown sequences of 2 letters that served as a priming and an imperative stimulus. In 3 randomly interspersed conditions the imperative stimulus had a 0.80, 0.50, or 0.20 probability of physically matching the priming letter. The different probability conditions were signaled by the position of a dot flanking the priming letter. Reaction time and accuracy data indicated that the subjects primed their responses as a function of the information conveyed by the priming stimulus. The amplitude and latency of the P300 to the priming stimulus were sensitive to the amount of information conveyed by the priming stimulus and the duration of the processing required. The readiness potential in the foreperiod was lateralized as a function of the priming stimulus. Furthermore, the larger the amplitude of the P300 to the priming stimulus, the larger the lateralization of the readiness potential, indicating that information extraction, indexed by the P300, was related to response priming, indexed by the readiness potential. The results indicate that ERP measures make manifest covert aspects of the priming process occurring in the foreperiod.

Adolescent↗

PubMed1990

Hemispheric processing of spatial frequencies in two commissurotomy patients.

To test the hypothesis that in humans the left brain hemisphere is specialized for processing high spatial frequencies while the right hemisphere is specialized for processing low spatial frequencies, pairs of Gaussian windowed sinusoidal gratings were presented for 167 msec within the left and right visual fields of two commissurotomy patients. The gratings employed had spatial frequencies ranging from 1 to 8 cycles per degree, and horizontal or vertical orientations. The two gratings in each pair were identical in spatial frequency but could differ in orientation. Subjects reported if their orientations were the same or different. Twelve normal controls were also run. Accuracy data provides no indication of a relative advantage for high frequencies in the RVF or low frequencies in the LVF. One commissurotomy subject showed a trend in the reverse direction; the other was better with LVF presentations for all spatial frequencies. Control subjects failed to show a spatial frequency x visual field interaction. These outcomes suggest that at the processing stages required by the task, the hemispheres are not specialized for particular ranges of spatial frequencies.

Adult↗

PubMed1995

Hemisphere asymmetry and the processing of emotional words in anxiety.

High- and low-trait anxious subjects participated in a divided visual field emotional Stroop task. Subjects identified the colour of unilaterally presented threat-related, positive and neutral words. The high- and low-trait groups differed in terms of their accuracy scores but not in their reaction times. Analysis of the accuracy data revealed that the high-trait group exhibited right hemisphere interference for emotional relative to neutral trials whereas the low-trait showed right hemisphere interference for threat-related trials only. The idea that the right hemisphere is differentially specialised for the processing of emotional information was supported.

Adult↗

PubMed1989

Are psychological disorders most prevalent among older adults? Examining the evidence.

A persistent popular and professional perception is the high rate of psychological disorders among older adults (age 65+), especially higher than among younger adults. To examine the perception's accuracy, data from all psychiatric epidemiology studies conducted since 1950 with random community samples were reviewed. The studies were divided into categories according to type of disorder and instrument used. Prevalence rates were recalculated to compare those under 65 and over with those aged 65 and over. The review reveals that in none of the impairment categories do the preponderance of studies document more disorders among older than younger adults. In contrast, studies indicate more disorders reported by younger than older adults for depressive symptoms, major depression (clinical), and clinical affective disorders. While several methodological caveats are warranted, available data do not support the prevailing perception that psychological disorders are most prevalent among older adults. Despite these findings, future policies should consider older adults a high priority for outpatient mental health services. Older persons use disproportionately fewer outpatient services than other adults; over-utilization of primary care services occurs among all age groups, including older persons; and finally, the co-occurrence of psychological and physical disorders often results in elders' mental disorders not being recognized or treated appropriately in the primary care sector.

Aged↗

PubMed1987

Recognition of letters traced in the right and left palms: evidence for a process-oriented tactile asymmetry.

Three experiments were conducted to examine the relative ability of the cerebral hemispheres to identify capital letters traced in the palms of the hands. In Experiment 1, letters were presented either right side up or upside down, and the subject's task was to name the letter aloud or point to an identical letter using the stimulated hand. Analysis of the accuracy data revealed that the left palm/right hemisphere (LP/RH) performed this task significantly better than did the right palm/left hemisphere (RP/LH), particularly when the stimuli were presented in the upside-down orientation. In Experiments 2 and 3, subjects performed the same letter identification task; however, on half the trials, they were required to maintain either a spatial or verbal concurrent memory load (i.e., a 24-point Vanderplas & Garvin form or six low-imagery nouns, respectively). In the no-load condition of Experiment 2 (spatial forms), the previously observed LP/RH advantage was replicated. However, in the load condition, this LP/RH superiority was no longer in evidence. In Experiment 3 (low-imagery nouns), the presence of a concurrent verbal task had minimal impact on the previously observed performance asymmetry as the LP/RH advantage was obtained in both the no-load and load conditions. The results of the three studies taken in composite suggest that (1) the operations utilized to identify letters traced in the palms of the hands are primarily spatial in nature and (2) that the observed performance asymmetry may be attributed to a right hemisphere superiority for the analysis and codification of information along a spatial dimension. These findings are discussed in terms of a "process-oriented" model of hemispheric asymmetry.

Attention↗

PubMed2005

Priming effects for affective vs. neutral faces.

Affective and Neutral Tasks (faces with negative or neutral content, with different lighting and orientation) requiring reaction time judgments of poser identity were administered to 32 participants. Speed and accuracy were better for the Affective than Neutral Task, consistent with literature suggesting facilitation of performance by affective content. Priming effects were significant for the Affective but not Neutral Task. An Explicit Post-Test indicated no conscious knowledge of the stimulus frequency that was associated with performance facilitation. Faster performance by female vs. male participants, and differential speeds and susceptibility to priming of different emotions were also found. Anger and shock were responded to most rapidly and accurately in several conditions, showed no gender differences, and showed significant priming for both RT and accuracy. Fear and pain were responded to least accurately, were associated with faster female than male reaction time, and the accuracy data showed a kind of reverse priming.

Adolescent↗

PubMed2006

Is action naming better preserved (than object naming) in Alzheimer's disease and why should we ask?

The present study compared object and action naming in patients with Alzheimer's dementia. We tested the hypothesis put forward in (some) previous studies that in Alzheimer's dementia the production of verbs, that is required in action naming, is better preserved than the production of nouns, that is required in object naming. The possible reason for the dissociation is that verbs are supported predominantly by frontal brain structures that may remain relatively better preserved in early Alzheimer's disease. Objects, on the other hand, are supported by temporal lobe structures that are affected early in the disease. An alternative hypothesis, which is supported by other studies, is that action naming is more impaired than object naming due to verbs being semantically more complex than nouns. In order to test these contrasting hypotheses, the present study used more stringent methodology than previous studies. We used a larger set of stimuli with carefully matched object and action items and we collected not only accuracy data but also naming latencies, a measure that is sensitive to even mild lexical retrieval problems. We compared the performance of 19 patients with mild to moderate Alzheimer's disease with that of 19 healthy age matched participants. We found that both the patients and the comparison group responded faster and made fewer errors on the object pictures than the action pictures. A qualitative analysis of the naming errors indicated that object and action naming pose different demands for the language system. The results overall suggest that the patients' performance is an exaggeration of the pattern present in the comparison participants.

Aged↗

PubMed2004

Direct resistively heated column gas chromatography (Ultrafast module-GC) for high-speed analysis of essential oils of differing complexities.

This study applies Ultrafast module-GC (UFM-GC) with direct resistively heated columns to routine analysis of a group of essential oils of differing complexities (chamomile, peppermint, rosemary and sage). Essential oils were analysed by conventional GC with conventional inner diameter (i.d.) columns (0.25 mm) of different lengths (5 and 25 m long) and by Fast GC and Ultrafast module-GC with narrow bore columns (0.1 mm i.d., 5 m long). Column performance were evaluated and compared through their Grob test, separation number and peak capacity. Ultrafast module-GC was successful in the qualitative and quantitative analysis of essential oils of different compositions with analysis times between 40 s and 2 min versus 20-60 min required by conventional GC. Critical pairs or groups of components were separated by carefully tuning selectivity of the stationary phase to compensate for loss of efficiency due to the use of short columns and high temperature rates. The Ultrafast module-GC results of peppermint e.o. analyses were also validated and compared to those obtained by conventional GC; by measuring precision over time (i.e. repeatability and intermediate precision) and accuracy. Ultrafast module-GC showed a good separation reproducibility affording reliable component identification through the relative retention times and quantitative determination through normalised peak areas. Accuracy data also showed that Ultrafast module-GC and conventional GC normalised areas and areas percentage were perfectly comparable.

Chromatography, Gas↗

PubMed2006

Eye movements and prospective memory: what the eyes can tell us about prospective memory.

In this study we used eye tracking methodology in combination with multi-element displays to examine the processes underlying event-based prospective memory in a visual search paradigm. In the task individuals searched for a different target stimulus (i.e., a letter) on each trial that could be present or absent, and made prospective responses to the letters D or M. The response accuracy data revealed that target hits were more frequent than prospective hits, and that there was no difference in response time for target and prospective responses. The eye tracking data revealed that both first and total fixation durations increased from distractors (stimuli that were neither targets nor prospective cues) to targets to prospective cues when a target or prospective response was made. These measures also revealed that the presence of a target in the display served to disrupt prospective memory. In addition, prospective memory misses resulted from a combination of failures to fixate the prospective cues and failures to engage in strategic processing of the prospective cues. These data demonstrate the utility of eye tracking methods in examining the processes underlying event-based prospective memory.

Analysis of Variance↗

PubMed2004

Confirmatory analysis of 17beta-boldenone, 17alpha-boldenone and androsta-1,4-diene-3,17-dione in bovine urine, faeces, feed and skin swab samples by liquid chromatography-electrospray ionisation tandem mass spectrometry.

The origin, i.e. natural occurrence or illegal treatment, of findings of 17alpha-boldenone (alpha-Bol) and 17beta-boldenone (beta-Bol) in urine and faeces of cattle is under debate within the European Union. A liquid chromatographic positive ion electrospray tandem mass spectrometric method is presented for the confirmatory analysis of 17beta-boldenone, 17alpha-boldenone and an important metabolite/precursor androsta-1,4-diene-3,17-dione (ADD), using deuterium-labelled 17beta-boldenone (beta-Bol-d3) as internal standard. Detailed sample preparation procedures were developed for a variety of sample matrices such as bovine urine, faeces, feed and skin swab samples. The method was validated as a quantitative confirmatory method according to the latest EU guidelines and shows good precision, linearity and accuracy data, and CCalpha and CCbeta values of 0.1-0.3 and 0.4-1.0 ng/ml, respectively. Currently, the method has been successfully applied to suspect urine samples for more than a year, and occasionally to faeces, feed and swab samples as well. Results obtained from untreated and treated animals are given and their impact on the debate about the origin of residues of 17beta-boldenone is critically discussed. Finally, preliminary data about the degree of conjugation of boldenone residues are presented and a simple procedure for discrimination between residues from abuse versus natural origin is proposed.

Anabolic Agents↗

PubMed2004

Analysis of glycerophosphoinositol by liquid chromatography-electrospray ionisation tandem mass spectrometry using a beta-cyclodextrin-bonded column.

Glycerophosphoinositol (GroPIns) has been demonstrated to have important roles in many intracellular regulatory processes. GroPIns has been analysed for many years by anion-exchange HPLC after radiolabelling of cells in culture, but no method has been developed, to our knowledge, for the direct detection and quantitation of the unlabelled compound in such biological samples. Here is reported a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the direct quantitative analysis of GroPIns that can indeed be applied to cell extracts. Analyses were performed on a beta-cyclodextrin-bonded HPLC column using a binary mobile phase of acetonitrile and 20 mM ammonium formate in water, which allowed direct on-line detection by tandem mass spectrometry in negative electrospray ionisation (ESI) mode. The method was applied to the quantitative analysis of GroPIns in selected rat cell lines after a two-phase acid extraction of cultured cells using external calibration. The potential matrix signal suppression effects were investigated by the parallel quantitation of GroPIns in extracts of selected cultured cell lines with both external calibration and the standard additions method. The accuracy data obtained demonstrated the feasibility of external calibration, so allowing a simpler and less time-consuming approach than that of the standard additions method.

Calibration↗

PubMed2004

Reversed-phase liquid chromatographic method with fluorescence detection for the simultaneous determination of albendazole sulphoxide, albendazole sulphone and albendazole 2-aminosulphone in sheep plasma.

A rapid and sensitive HPLC method for the simultaneous quantification of albendazole sulphoxide (ABZ-SO), albendazole sulphone (ABZ-SO2) and albendazole 2-aminosulphone (ABZ-SO2NH2) in sheep blood plasma has been developed. Plasma samples were extracted with ethyl acetate under alkaline conditions. Separation was achieved on a C18 reversed-phase analytical column, in the presence of positively- (tetra-n-butylammonium hydrogen sulphate) and negatively-charged (octanesulphonate sodium) pairing ions, while detection was performed fluorometrically. Excitation and emission wavelengths were 290 and 320 nm, respectively. Limits of quantification were defined at 39 ng/ml for ABZ-SO, 4.95 ng/ml for ABZ-SO2 and 4 ng/ml for ABZ-SO2NH2. Accuracy data, in terms of recovery efficiency showed overall values (+/- S.E.M.) of 85.6 +/- 1.0% for ABZ-SO, 100.0 +/- 1.0% for ABZ-SO2 and 89.1 +/- 0.6% for ABZ-SO2NH2. The method was successfully applied to quantitatively determine the three albendazole metabolites in plasma samples collected from sheep that had been orally administered albendazole.

Albendazole↗