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PubMed1989

Mammographic film-processor temperature, development time, and chemistry: effect on dose, contrast, and noise.

Six different combinations of film-processor temperature (33.3 degrees C, 35 degrees C), development time (22 sec, 44 sec), and chemistry (Du Pont medium contrast developer [MCD] and Kodak rapid process [RP] developer) were each evaluated by separate analyses with Hurter and Driffield curves, test images of plastic step wedges, noise variance analysis, and phantom images; each combination also was evaluated clinically. Du Pont MCD chemistry produced greater contrast than did Kodak RP chemistry. A change in temperature from 33.3 degrees C (92 degrees F) to 35 degrees C (95 degrees F) had the least effect on dose and image contrast. Temperatures of 36.7 degrees C (98 degrees F) and 38.3 degrees C (101 degrees F) also were tested with extended processing. The speed increased for 36.7 degrees C but decreased at 38.3 degrees C. Base plus fog increased, but contrast decreased for these higher temperatures. Increasing development time had the greatest effect on decreasing the dose required for equivalent film darkening when imaging BR12 breast equivalent test objects; ion chamber measurements showed a 32% reduction in dose when the development time was increased from 22 to 44 sec. Although noise variance doubled in images processed with the extended development time, diagnostic capability was not compromised. Extending the processing time for mammographic films was an effective method of dose reduction, whereas varying the processing temperature and chemicals had less effect on contrast and dose.

Female↗

PubMed2002

Effects of cognitive training interventions with older adults: a randomized controlled trial.

CONTEXT: Cognitive function in older adults is related to independent living and need for care. However, few studies have addressed whether improving cognitive functions might have short- or long-term effects on activities related to living independently. OBJECTIVE: To evaluate whether 3 cognitive training interventions improve mental abilities and daily functioning in older, independent-living adults. DESIGN: Randomized, controlled, single-blind trial with recruitment conducted from March 1998 to October 1999 and 2-year follow-up through December 2001. SETTING AND PARTICIPANTS: Volunteer sample of 2832 persons aged 65 to 94 years recruited from senior housing, community centers, and hospital/clinics in 6 metropolitan areas in the United States. INTERVENTIONS: Participants were randomly assigned to 1 of 4 groups: 10-session group training for memory (verbal episodic memory; n = 711), or reasoning (ability to solve problems that follow a serial pattern; n = 705), or speed of processing (visual search and identification; n = 712); or a no-contact control group (n = 704). For the 3 treatment groups, 4-session booster training was offered to a 60% random sample 11 months later. MAIN OUTCOME MEASURES: Cognitive function and cognitively demanding everyday functioning. RESULTS: Thirty participants were incorrectly randomized and were excluded from the analysis. Each intervention improved the targeted cognitive ability compared with baseline, durable to 2 years (P<.001 for all). Eighty-seven percent of speed-, 74% of reasoning-, and 26% of memory-trained participants demonstrated reliable cognitive improvement immediately after the intervention period. Booster training enhanced training gains in speed (P<.001) and reasoning (P<.001) interventions (speed booster, 92%; no booster, 68%; reasoning booster, 72%; no booster, 49%), which were maintained at 2-year follow-up (P<.001 for both). No training effects on everyday functioning were detected at 2 years. CONCLUSIONS: Results support the effectiveness and durability of the cognitive training interventions in improving targeted cognitive abilities. Training effects were of a magnitude equivalent to the amount of decline expected in elderly persons without dementia over 7- to 14-year intervals. Because of minimal functional decline across all groups, longer follow-up is likely required to observe training effects on everyday function.

Activities of Daily Living↗

PubMed1993

Testing the effects of hypnotics on memory via the telephone: fact or fiction?

The two benzodiazapines used in this experiment, namely midazolam and flunitrazepam, have both been shown to have effects on memory processing in laboratory studies. In spite of the potential hazards involved in real life testing, it should be possible to replicate such findings in everyday environments and it is argued that a successful replication would be a very meaningful extension to the existing laboratory data. The present study was successful in producing significant "hangover" effects in healthy volunteers using a novel "user-friendly" telephone testing technique. Compared to placebo, the two hypnotics reduced speed of processing in tasks which required retrieval from long-term semantic memory (semantic verification) and the manipulation of material in working memory (syntactic reasoning). We suggest that this new method offers the potential for carrying out large-scale psychopharmacological studies with real patients and achieves a meaningful step forward in the search for ecological validity.

Adult↗

PubMed2006

Interrelationship and familiality of dyslexia related quantitative measures.

Dyslexia is a complex gene-environment disorder with poorly understood etiology that affects about 5% of school-age children. Dyslexia occurs in all languages and is associated with a high level of social and psychological morbidity for the individual and their family; approximately 40-50% have persistent disability into adulthood. The core symptoms are word reading and spelling deficits, but several other cognitive components influence the core phenotype. A broad spectrum of dyslexia related phenotypes, including phonological decoding, phoneme awareness, orthographic processing, short-term memory, rapid naming and basic mathematical abilities, were investigated in large sample of 287 German dyslexia families. We explored the interrelationship between the component phenotypes using correlation and principal component analyses (PCA). In addition, we estimated familiality for phenotypes as well as for the factors suggested by PCA. The correlation between the component phenotypes varied between -0.1 and 0.7. The PCA resulted in three factors: a general dyslexia factor, a speed of processing factor and a mathematical abilities factor. The familiality estimates of single components and factors ranged between 0.25 and 0.63. Instead of analyzing single dyslexia-related components, multivariate analyses including factor analytic approaches may help in the identification of susceptibility genes.

Adolescent↗

PubMed1991

An update on wound management.

This article provides an update on wound management with wound diagnosis and treatment discussed in terms of the normal cellular events of the wound healing process. The role of growth factors as cell regulators, the importance of wound fluids to wound metabolism, and the deleterious effects of some wound cleansers, disinfectants, and modalities are reviewed. Treatment guidelines are suggested based on negative or positive cellular response to individual management techniques. Wound evaluation, diagnosis, and treatment are considered in terms of a new color concept that simplifies clinical decision making. An explanation of the relatively new microenvironmental dressings designed to maintain wound humidity and speed wound healing is provided. A more physiologic approach to managing the simple and complex wound may prove to speed the process of epithelialization, contraction, and collagen deposition while diminishing the problems associated with delayed or inadequate healing. The wound healing process is subject to manipulation and facilitation by the clinician, a concept that is certain to receive much attention in the next decade. The importance of a scientific approach to this aspect of our discipline cannot be overemphasized.

Hand Injuries↗

PubMed2005

Impaired implicit sequence learning in depression: a probe for frontostriatal dysfunction?

BACKGROUND: Implicit learning through motor sequencing tasks is sensitive to basal ganglia dysfunction. Consequently, it is ideally suited for testing elements of the frontostriatal model of major depression and performance can be related to key clinical, neuropsychological, vascular and biochemical data. METHOD: Twenty-one subjects with moderate to severe unipolar depression and 21 age-, sex- and education-matched controls were recruited. Clinical, vascular and biochemical data were recorded. Subjects were administered a battery of neuropsychological tests that assessed speed of processing, working memory, learning, memory, language, perceptual organization and executive functioning. Additionally, subjects were administered a motor sequencing implicit learning task. Implicit learning is assumed when reaction times improve during the sequenced condition as compared to the pseudo-random baseline condition. RESULTS: The rate of implicit learning in persons with depression was only half that of control subjects (3.6% v. 7.3%). Lower rates of implicit learning in patients were associated with poorer performance on neuropsychological tests of visuomotor speed and mental flexibility, longer duration of depressive episode and severity of acute stress. In a small number of subjects, poorer performance was also related to past suicide attempt. CONCLUSIONS: Impaired implicit learning in persons with depression is consistent with frontostriatal dysfunction. Performance is related to some clinical characteristics and to neuropsychological functioning on tests of visuomotor speed and mental flexibility.

Adult↗

PubMed2005

Contributions of processing ability and knowledge to verbal memory tasks across the adult life-span.

This study investigated the relationships of processing capacity and knowledge to memory measures that varied in retrieval difficulty and reliance on verbal knowledge in an adult life-span sample (N = 341). It was hypothesized that processing ability (speed and working memory) would have the strongest relationship to tasks requiring active retrieval and that knowledge (vocabulary ability) would be related to verbal fluency and cued recall, as participants relied upon verbal knowledge to retrieve category items (fluency) or develop associations (cued recall). Measurement and structural equation models were developed for the entire sample and separately for younger (aged 20-54 years, n = 168) and older (aged 55-92 years, n = 173) subgroups. In accordance with the hypotheses, processing ability was found to be most highly related to free recall, with additional significant relationships to cued recall, verbal fluency, and recognition. Knowledge was found to be significantly related only to verbal fluency and to cued recall. Moreover, knowledge was more important for older than for younger adults in mediating variance in cued recall, suggesting that older adults may use age-related increases in knowledge to partially compensate for processing declines when environmental support is available in memory tasks.

Adult↗

PubMed2006

Fast calculation system specialized for head-related transfer function based on boundary element method.

Recently, development of a numerical calculation of the head-related transfer function (HRTF) has been conducted using a computer model of a human head and the boundary element method. The reciprocity theorem is incorporated into the computational process in order to shorten the computational time, which is otherwise very long. On the other hand, another fast HRTF calculation method for any source position, which is realized by calculating factors independent of the source position in advance, has been suggested by the authors. Using this algorithm, the HRTF for any source position can be obtained in a few seconds with a common PC. The resulting HRTFs are more precise and are calculated faster than those by using the reciprocity theorem. However, speeding the process up even further is required in order to respond to a head movement and rotation or to moving sources during binaural sound reproduction. In this paper, a faster calculation method by incorporating a time domain operation into the authors' previous algorithm is proposed. Additionally, the new formulation, which eliminates the extra computational time in the preprocess, is proposed. This method is shown to be faster than the previous ones, but there are some discrepancies at higher frequencies.

Acoustics↗

PubMed1998

Age differences in decision making: to take a risk or not?

A controlled laboratory experiment was used to assess the efficacy of the cognitive processes that underlie risk taking decision making in young and elderly people. Thirty-six participants took part in the study: half the subjects were elderly (mean age of 74) and the other half were young adults (mean age of 19). The elderly participants made equivalent decisions to those of the control young adults. Both age-groups of participants systematically and comparably changed their behavior as a function of risk levels. Furthermore, the elderly participants, relative to young adults, did not exhibit any slowing down in the speed of processing the information involved in making risk taking decisions, reflecting that healthy elderly people are cognitively apt to making risk taking decisions. Both age-groups took comparably less time on the easy trials (trials with either low or high levels of risk) and comparably more time on the difficult trials (trials with medium levels of risk).

Adolescent↗

PubMed1998

Deficits in the control of the attentional focus in chronic schizophrenics.

The ability to control the size of the attentional focus and thus to modulate processing efficiency was investigated using simple reaction times in central vision in 17 chronic schizophrenic patients and 17 normal control subjects. The size of the attentional focus was manipulated by varying the size of a central box (i.e., a pre-cue), where the imperative stimulus appeared. In accordance with previous studies, in normal controls reaction time increased with box size. In contrast, in schizophrenic patients reaction time did not depend on box size. That is, schizophrenic patients did not show the inverse relation between size of the box and speed of processing, which is observed in normal controls. These results suggest that a deficit in controlling the size of the attentional focus is a basic impairment in chronic schizophrenia. It was also found that schizophrenics are more susceptible than controls to paracontrast.

Adult↗

PubMed2004

Robust denoising of electrophoresis and mass spectrometry signals with minimum description length principle.

The need for high-throughput assays in molecular biology places increasing requirements on the applied signal processing and modelling methods. In order to be able to extract useful information from the measurements, the removal of undesirable signal characteristics such as random noise is required. This can be done in a quite elegant and efficient way by the minimum description length (MDL) principle, which treats and separates 'noise' from the useful information as that part in the data that cannot be compressed. In its current form the MDL denoising method assumes the Gaussian noise model but does not require any ad hoc parameter settings. It provides a basis for high-speed automated processing systems without requiring continual user interventions to validate the results as in the conventional signal processing methods. Our analysis of the denoising problem in mass spectrometry, capillary electrophoresis genotyping, and sequencing signals suggests that the MDL denoising method produces robust and intuitively appealing results sometimes even in situations where competing approaches perform poorly.

Algorithms↗

PubMed1976

Comparison of nonretarded and mentally retarded children on a perceptual learning task.

The performances of 12 EMR and 12 nonretarded sixth-grade children on a perceptual learning task were compared to investigate the information processing of visually presented stimuli in individuals with different intelligence levels. A minicomputer flashed either familiar (lowercase) or unfamiliar letters (Gibson-like figures) in either a stimultaneous or successive mode on a same-different matching task. The computer automatically calculated accuracy and latency data for each subject. Results showed that accuracy was superior in the nonretarded group and that mean latencies for the EMR group was consistently higher than those of the nonretarded group. However, when latencies were corrected for differences in basic reaction time, there were no significant differences between the groups in the speed of processing the information.

Attention↗

PubMed2006

Ebbie: automated analysis and storage of small RNA cloning data using a dynamic web server.

BACKGROUND: DNA sequencing is used ubiquitously: from deciphering genomes to determining the primary sequence of small RNAs (smRNAs). The cloning of smRNAs is currently the most conventional method to determine the actual sequence of these important regulators of gene expression. Typical smRNA cloning projects involve the sequencing of hundreds to thousands of smRNA clones that are delimited at their 5' and 3' ends by fixed sequence regions. These primers result from the biochemical protocol used to isolate and convert the smRNA into clonable PCR products. Recently we completed a smRNA cloning project involving tobacco plants, where analysis was required for approximately 700 smRNA sequences. Finding no easily accessible research tool to enter and analyze smRNA sequences we developed Ebbie to assist us with our study. RESULTS: Ebbie is a semi-automated smRNA cloning data processing algorithm, which initially searches for any substring within a DNA sequencing text file, which is flanked by two constant strings. The substring, also termed smRNA or insert, is stored in a MySQL and BlastN database. These inserts are then compared using BlastN to locally installed databases allowing the rapid comparison of the insert to both the growing smRNA database and to other static sequence databases. Our laboratory used Ebbie to analyze scores of DNA sequencing data originating from an smRNA cloning project. Through its built-in instant analysis of all inserts using BlastN, we were able to quickly identify 33 groups of smRNAs from approximately 700 database entries. This clustering allowed the easy identification of novel and highly expressed clusters of smRNAs. Ebbie is available under GNU GPL and currently implemented on http://bioinformatics.org/ebbie/. CONCLUSION: Ebbie was designed for medium sized smRNA cloning projects with about 1,000 database entries. Ebbie can be used for any type of sequence analysis where two constant primer regions flank a sequence of interest. The reliable storage of inserts, and their annotation in a MySQL database, BlastN comparison of new inserts to dynamic and static databases make it a powerful new tool in any laboratory using DNA sequencing. Ebbie also prevents manual mistakes during the excision process and speeds up annotation and data-entry. Once the server is installed locally, its access can be restricted to protect sensitive new DNA sequencing data. Ebbie was primarily designed for smRNA cloning projects, but can be applied to a variety of RNA and DNA cloning projects.

Algorithms↗

PubMed2000

Biobehavioral characteristics of nondemented older adults with subclinical brain atrophy.

OBJECTIVE: To characterize the risk factors and neuropsychological performance of two subgroups of community-dwelling, white elderly men free of severe cognitive impairment (n = 383; mean age, 72.9 +/- 3.0 years) who differ on volumetric measurements of total brain parenchyma and white matter hyperintensity (WMH) volumes. METHODS: Group comparisons were made of cerebrovascular disease risk factors measured at the time of imaging and at three prior examinations extending over 25 years of adult life. Measures of verbal memory and speed psychomotor processing at the time of imaging and 10 years before imaging were also available. RESULTS: Compared with those in the "nonatrophy" group, individuals in the subgroup with "atrophy" (defined by low total brain volume and high WMH volume) were older, reported a higher level of depressive symptomatology, experienced a steeper decline in diastolic blood pressure (DBP) and a steeper increase in pulse pressure, were less physically active, had smoked for more years, and had a higher prevalence of several cardiovascular disease indicators, including an ankle/arm systolic blood pressure ratio less than 0.9, and hypertension. After multivariate analysis, the 25-year decline in DBP, the number of years smoked, and an ankle/arm index of less than 0.9 remained significant discriminators of the two groups. Lower levels of speeded performance at the time of imaging and a steeper 10-year decline in cognitive performance on selected tests were also observed in the atrophic group. CONCLUSION: Community-dwelling older adults with volumetric brain measurements associated with accelerated aging are distinguishable on the basis of several health-related characteristics. These individuals also perform less well on certain tasks involving executive functioning.

Adult↗

PubMed2002

Control of a hand grasp neuroprosthesis using an electroencephalogram-triggered switch: demonstration of improvements in performance using wavepacket analysis.

Volitionally modulated electroencephalographic (EEG) waves were monitored for the purpose of controlling a hand neuroprosthesis in people with tetraplegia. The region of the EEG signal spectrum monitored was the occipital alpha wave (8-13 Hz), and volitional modulation was achieved with the opening and closing of the eyes. In a set of 13 trials evaluated, a subject with tetraplegia successfully completed ten trials undertaking stimulated grasp and release using the EEG-triggered switch. EEG signal data recorded during the 13 trials were also post-processed off-line using wavepacket analysis. Following this signal processing, the speed and reliability of the EEG-triggered switch, when operated by the subject with tetraplegia, was significantly improved (p < 0.002). Such improvements provide system performance that is likely to be acceptable to a neuroprosthesis user during activities of daily life.

Electric Stimulation↗

PubMedDate not supplied

Mass data massage: an automated data processing system used for NHEXAS, Arizona. National Human Exposure Assessment Survey.

Data entry and management are critical components of all large survey projects; data quality objectives must be met and data must be quickly and readily accessible. We developed a comprehensive system for data entry and management utilizing scannable forms with bubble fields and handwriting recognition. This 'Mass Data Massage' (MDM) system had three components: (1) form creation and database definition; (2) programming of data dictionaries for documentation and preliminary logic and range checks; and (3) data entry, management and documentation using the 'Mass Data Cleaning Program' (MDCP). Scannable forms were written in Teleform, where the data field definition, variable names and ranges were defined as the form was created. Completed forms were returned from the field, subjected to final field quality control (QC) checks, and transferred to the data management section. They were batched and coded as necessary. Once a batch of data was scanned and visually verified, the operator called up the menu for the MDCP. The MDCP had 31 program modules with 500-1200 lines of code each. The operator could select and run the appropriate dictionary on each data batch 'correcting' apparent errors in responses. This process was iterative until the data batch passed all dictionary checks. Proposed 'changes' were forwarded to the data coordinator (DC) for acceptance or rejection. After all errors had been resolved, each data batch was subjected to a 10% quality assurance (QA) check. The original data batch and associated file of applied changes were archived. Time expenditure using the scanning approach varied with the number of questions and the types of responses (handwritten or bubble fields). One-page forms took 42-60% of the time needed for hand entry; forms longer than 10 pages took 35-38% of the time. Use of faster machines will further speed the process. The main advantage of the system was the reduction of systematic errors. Scanning alone reduced errors found on 995 NHEXAS Baseline Questionnaires. Overall, the dictionary identified 0.55% errors on the scanned forms. Ten percent QC checks, performed on corrected batches ready for appendage to the master database, revealed an overall error rate of 0.02%. Similar checks on a laboratory form scanned from numeric handwriting detected 0.3% errors following dictionary application and 0.2% errors during the 10% QA check. This system was faster, more accurate, and more cost-effective than hand entry of data. A batch of data that took >1 week to process using the hand entry method was processed within 1 day using MDM. Human coding of specific answers and the final verification were the most time-consuming processes.

Arizona↗

PubMed1990

Event-related potentials to visual and language stimuli in normal and dyslexic children.

Event-related potentials (ERPs) were recorded in 31 normal and 21 dyslexic children, the latter with visual processing impairment, in three visual reading-related tasks: a nonalphabetic, an alphabetic, and a lexical decision task (two levels of difficulty in each). ERPs were recorded from fifteen active electrodes for 1.5 s following stimulus presentation; analyses were done on difference waves. N2 and P3 components were usually longer in latency and P3 was lower in amplitude in the dyslexic than in the normal children. The P3 had a flatter, broader distribution in the dyslexics than in the controls, which was very similar to the effect of difficulty in the two easier tasks. The lack of Group X Age interactions is inconsistent with either a maturational lag between the groups of children, or with the dyslexic children catching up to normals in terms of their speed of processing. Thus, the dyslexic children required more time to process the visual information across tasks (with only their letter classification being equal to that of the normal controls) and approved to have a different developmental pattern in their ERPs from that of the normal children.

Arousal↗

PubMed1999

Do the global advantage and interference effects covary?

The global precedence hypothesis has been operationally defined as a faster or earlier processing of the global than of the local properties of an image (global advantage) and as interference by processing at the global level with processing at the local level (global interference). Navon (1977) proposed an association between the global advantage and interference effects. Other studies have shown a dissociation between the two effects (e.g., Lamb & Robertson, 1988). It seems that the controversy in previous research resulted from not equalizing the eccentricities of global and local properties. In the present study, the eccentricities of the two levels were equalized by using stimuli with all their elements located along their perimeters. The results of the first experiment demonstrated that although the global level was identified faster than the local level in both the central and the peripheral locations of the visual field (global advantage), the pattern of global interference varied across the visual field. Consistency of global and local levels increased the speed of processing of the local level displayed at the center of the visual field but slowed down the processing of that level at peripheral locations. The results of Experiment 2 demonstrated that it was most likely that the variation in the pattern of global interference was determined by the variable of eccentricity, rather than by the sizes of the global and local levels.

Fixation, Ocular↗