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At least 793 records · Page 44Linked to original sources

PubMed2005

Recognizing people from their movement.

Human observers demonstrate impressive visual sensitivity to human movement. What defines this sensitivity? If motor experience influences the visual analysis of action, then observers should be most sensitive to their own movements. If view-dependent visual experience determines visual sensitivity to human movement, then observers should be most sensitive to the movements of their friends. To test these predictions, participants viewed sagittal displays of point-light depictions of themselves, their friends, and strangers performing various actions. In actor identification and discrimination tasks, sensitivity to one's own motion was highest. Visual sensitivity to friends', but not strangers', actions was above chance. Performance was action dependent. Control studies yielded chance performance with inverted and static displays, suggesting that form and low-motion cues did not define performance. These results suggest that both motor and visual experience define visual sensitivity to human action.

Affect↗

PubMed1983

Computer-assisted versus visual lung gallium-67 index in normal subjects and in patients with interstitial lung disorders.

The pulmonary uptake of 87Ga citrate has been proposed as an index that assists clinical decision-making in patients with certain interstitial lung diseases. Such use, however, requires definition of the range of normal values, the range of values in patients with various interstitial diseases, and interobserver and intraobserver variability. We studied 9 normal subjects and 15 patients with interstitial lung diseases. The 87Ga indexes were determined by visual analysis and by a computer-assisted method. We found that the variation among experienced observers in visual index values was substantial in both normal subjects and patients, and that the computer-assisted indexes were less variable. These data suggest that if this approach is to be used in clinical decision-making: (1) the variability of visual indexes, and of normal values, should be recognized; (2) consideration should be given to a less subjective, computer-assisted method of index calculation; (3) each institution should establish standardized methodology and consider determination of its range of variability and normal index values.

Adult↗

PubMed1977

Time-series analysis in operant research.

A time-series method is presented, nontechnically, for analysis of data generated in individual-subject operant studies, and is recommended as a supplement to visual analysis of behavior change in reversal or multiple-baseline experiments. The method can be used to identify three kinds of statistically significant behavior change: (a) changes in score levels from one experimental phase to another, (b) reliable upward or downward trends in scores, and (c) changes in trends between phases. The detection of, and reliance on, serial dependency (autocorrelation among temporally adjacent scores) in individual-subject behavioral scores is emphasized. Examples of published data from the operant literature are used to illustrate the time-series method.

Journal Article↗

PubMed1990

Methodology of ECG interpretation in the Louvain program.

The Louvain program performs the analysis and interpretation of the vectorcardiogram (VCG) to increase the clinical utility of ECG analysis. Among its original features, there are (1) a high-resolution vector-loop display for visual analysis, (2) quantitative analysis of the spatial VCG using age-sex stratified limits, (3) separate software for adult and pediatric series and (4) complementary deterministic and statistical methods of diagnostic classification. Using objective, ECG-independent evidence as a reference standard, the Louvain program has shown satisfactory levels of diagnostic accuracy in most basic categories. However, its usefulness is especially marked in "borderline" or "complex" situations, where the 12-lead ECG cannot provide a clear answer. It corresponds to the concept of "computer-assisted ECG interpretation" as opposed to "computer ECG analysis".

Adult↗

PubMed1995

VS--a new computer program for detailed offline analysis of visual-spatial perception.

A new IBM-AT-compatible software program, VS, for the analysis of visual-spatial (VS) perception in humans, especially brain-damaged patients, is described. VS is suitable for analysis of the following visual-spatial tests: (1) subjective visual vertical (SVV), (2) subjective visual horizontal (SVH), and (3) orientation, length, distance, form and position discrimination, as well as line/bar bisection. The program allows manipulation of a wide range of experimental tasks by varying relevant parameters, e.g., length, width, color, movement direction, step width, and position on screen of the stimuli. Psychophysical parameters are computed (methods of limits) and stored in dBASE files which can be retrieved for further data analysis with commercial statistics or graphics software. VS has a versatile text editor, with two macro languages which enables the user to define their own experimental configurations and realize individual graphic plots on screen or laser printer. VS incorporates two standard examinations together with normative data of control subjects and standard plots of the subject's performance. The results of separate investigations show highly stable results in normal control subjects in repeated examinations as well as good retest-reliability of these standard examinations in brain-damaged patients (rtt = 0.77). Representative case reports of a patient with left-sided visual neglect, a patient with Balint's syndrome as well as a patient with visual-spatial deficits subsequent to a left parietal brain lesion demonstrate the sensitivity and specificity of the program.

Adult↗

PubMed1999

Scotopic sensitivity/Irlen syndrome and the use of coloured filters: a long-term placebo-controlled study of reading strategies using analysis of miscue.

This study investigated the long-term effects of using coloured filters on the frequency and type of errors in oral reading. A double-masked, placebo-controlled crossover experimental design was used, with subjects being assessed over a period of 20 months. There were three experimental groups (Placebo tints, Blue tints, and Diagnosed tints) involving 113 subjects with reading difficulties, ranging in age from 9.2 yr. to 13.1 yr. The 35 controls (ranging in age from 9.4 yr. to 12.9 yr.) had reading difficulties but did not require coloured filters. There was a significant improvement for all groups in the accuracy of miscues over the period, although experimental groups over-all did not improve at a significantly different rate than the control group. The failure to find significantly greater improvement for the experimental groups over the control group for the total period, despite subjects' reports of improved print clarity, may be partly related to the lack of effective letter-sound analysis and synthesis skills and to the use of a word-identification strategy of guessing based on partial visual analysis.

Adolescent↗

PubMed1996

Visual and different automatic scoring profiles of respiratory variables in the diagnosis of sleep apnoea-hypopnoea syndrome.

The purpose of our study was to explore the diagnostic accuracy of different methods of scoring night time recording of respiratory variables (NTRRV) for the diagnosis of the sleep apnoea-hypopnoea syndrome (SAHS). Within a 2 week period, we performed a partially attended night time recording of respiratory variables and a full polysomnography (PSG) for reference in patients with suspected SAHS. Night time recording of respiratory variables was carried out using equipment which records, and continuously displays on a monitor, oximetry, airflow, chest and abdominal motion and body position. Night time recording of respiratory variables was scored manually and automatically, according to different combinations of the parameters described previously. Full polysomnography was performed in the Sleep Laboratory following conventional standards. Thirty six patients were studied. Visual analysis and different automatic scoring profiles of night time recording of respiratory variables were compared to full polysomnography in terms of agreement, sensitivity and specificity. Visual scoring of night time recording of respiratory variables gave the finest agreement-sensitivity-specificity relationship. Automatic scoring of nighttime recording of respiratory variables showed a trend to underestimate the apnoea-hypopnoea index (AHI) with respect to full polysomnography due mainly to underrecognition of hypopnoeas. Agreement-sensitivity-specificity relationships of automatic night time recording of respiratory variables with respect to full polysomnography varied depending on the automatic profile used. Some had a good agreement and sensitivity whilst others had a good specificity. These findings show that visual scoring of night time recording of respiratory variables is the most accurate method of analysis when compared to full polysomnography. The usefulness of the automatic methods of scoring of respiratory variables depends on the end-point chosen and is not reliable enough to be used in all situations. Night time recording of respiratory variables represents a real complement to conventional full polysomnography in clinical practice.

Adult↗

PubMed1999

Rapid Quantitative Analysis of Individual (18)FDG-PET Scans.

To evaluate an objective, quantitative, semi-automatic method of single (18)FDG-PET scan analysis. Scans of 60 normal controls was compared to scans from individuals with known pathology using two methods of visual analysis and Statistical Parametric Mapping with two different smoothing filters. We analyzed the sensitivity, specificity, and accuracy of each technique and evaluated the agreement between the four methods using a kappa statistic. When corrected for false positives, which were due to anatomical distortions, all techniques had a sensitivity and accuracy of 0.5 to 0.6. Specificity was highest, 1.0, using SPM with a 16 mm smoothing filter, followed by visual analyses. Good agreement between all techniques was found. A computerized expert which makes use of a normal data base and SPM to analyze single (18)FDG-PET scans can aid in the routine interpretation of scans and provide rapid, quantification of abnormalities for research or clinical purposes.

Journal Article↗

PubMed2003

Improvements to CluSTr: the database of SWISS-PROT+TrEMBL protein clusters.

The CluSTr database (http://www.ebi.ac.uk/clustr/) offers an automatic classification of SWISS-PROT+TrEMBL proteins into groups of related proteins. The clustering is based on analysis of all pair-wise sequence comparisons between proteins using the Smith-Waterman algorithm. The analysis, carried out on different levels of protein similarity, yields a hierarchical organization of clusters. Information about domain content of the clustered proteins is provided via the InterPro resource. The introduced InterPro 'condensed graphical view' simplifies the visual analysis of represented domain architectures. Integrated applications allow users to visualize and edit multiple alignments and build sequence divergence trees. Links to the relevant structural data in Protein Data Bank (PDB) and Homology derived Secondary Structure of Proteins (HSSP) are also provided.

Animals↗

PubMedDate not supplied

Automated three-dimensional quantification of myocardial perfusion and brain SPECT.

To allow automated and objective reading of nuclear medicine tomography, we have developed a set of tools for clinical analysis of myocardial perfusion tomography (PERFIT) and Brain SPECT/PET (BRASS). We exploit algorithms for image registration and use three-dimensional (3D) "normal models" for individual patient comparisons to composite datasets on a "voxel-by-voxel basis" in order to automatically determine the statistically significant abnormalities. A multistage, 3D iterative inter-subject registration of patient images to normal templates is applied, including automated masking of the external activity before final fit. In separate projects, the software has been applied to the analysis of myocardial perfusion SPECT, as well as brain SPECT and PET data. Automatic reading was consistent with visual analysis; it can be applied to the whole spectrum of clinical images, and aid physicians in the daily interpretation of tomographic nuclear medicine images.

Algorithms↗

PubMed2002

Visual agnosia and prosopagnosia in childhood: a prospective case study.

Selective impairments in visual processing are well documented in adults but rarely reported in children. The few childhood cases reported are mostly retrospective accounts with little attention paid to developmental, assessment or management issues. We report a prospective case study of a boy with prosopagnosia and visual processing deficits of presumed developmental origin. At the age of 4 years, AL presented with a range of cognitive and visual recognition deficits. Subsequent assessments revealed an evolving pattern in visual recognition and dissociations between developing skills. At the age of 7 AL has impairments in early perceptual analysis, visual organisation and in complex visual processing. Although he can identify facial features and match faces he is unable to recognise familiar faces. His reading and spelling are developing normally. The nature of his deficits and his progress are discussed within a cognitive neuropsychological framework.

Achievement↗

PubMed2006

SBEAMS-Microarray: database software supporting genomic expression analyses for systems biology.

BACKGROUND: The biological information in genomic expression data can be understood, and computationally extracted, in the context of systems of interacting molecules. The automation of this information extraction requires high throughput management and analysis of genomic expression data, and integration of these data with other data types. RESULTS: SBEAMS-Microarray, a module of the open-source Systems Biology Experiment Analysis Management System (SBEAMS), enables MIAME-compliant storage, management, analysis, and integration of high-throughput genomic expression data. It is interoperable with the Cytoscape network integration, visualization, analysis, and modeling software platform. CONCLUSION: SBEAMS-Microarray provides end-to-end support for genomic expression analyses for network-based systems biology research.

Chromosome Mapping↗

PubMed2005

Visual functioning and quality of life in the SubFoveal Radiotherapy Study (SFRADS): SFRADS report 2.

AIMS: To determine whether or not self reported visual functioning and quality of life in patients with choroidal neovascularisation caused by age related macular degeneration (AMD) is better in those treated with 12 Gy external beam radiotherapy in comparison with untreated subjects. METHODS: A multicentre single masked randomised controlled trial of 12 Gy of external beam radiation therapy (EBRT) delivered as 6 x 2 Gy fractions to the macula of an affected eye versus observation. Patients with AMD, aged 60 years or over, in three UK hospital units, who had subfoveal CNV and a visual acuity equal to or better than 6/60 (logMAR 1.0). METHODS: Data from 199 eligible participants who were randomly assigned to 12 Gy teletherapy or observation were available for analysis. Visual function assessment, ophthalmic examination, and fundus fluorescein angiography were undertaken at baseline and at 3, 6, 12, and 24 months after study entry. To assess patient centred outcomes, subjects were asked to complete the Daily Living Tasks Dependent on Vision (DLTV) and the SF-36 questionnaires at baseline, 6, 12, and 24 months after enrolment to the study. Cross sectional and longitudinal analyses were conducted using arm of study as grouping variable. Regression analysis was employed to adjust for the effect of baseline co-variates on outcome at 12 months and 24 months. RESULTS: Both control and treated subjects had significant losses in visual functioning as seen by a progressive decline in mean scores in the four dimensions of the DLTV. There were no statistically significant differences between treatment and control subjects in any of dimensions of the DLTV at 12 months or 24 months after study entry. Regression analysis confirmed that treatment status had no effect on the change in DLTV dimensional scores. CONCLUSIONS: The small benefits noted in clinical measures of vision in treated eyes did not translate into better self reported visual functioning in patients who received treatment when compared with the control arm. These findings have implications for the design of future clinical trials and studies.

Activities of Daily Living↗

PubMed1995

Spectral analysis of fetal heart rate in flat recordings.

Flat heart rate recordings may be observed in different fetal states such as chronic distress and sleep. Their visual analysis do not allow the distinction between these two states. We used spectral analysis to study the heart rate patterns in 25 fetuses. Two significant (P < 5 x 10(-5)) groups were apparent from the determination of the position of the maximum energy peak (PMEP) in the high-frequency band (0.20-0.50 Hz): a PMEP at about 0.20 Hz (group 1), and another around 0.30 Hz (group 2). The two groups did not differ in spectral density (SD). The outcome of neonates showed that group 1 fetuses made good progress and produced healthy neonates; whereas group 2 comprised cases of chronic fetal distress, or even death in utero, and neonatal distress. The significance of this difference in PMEP between fetal heart rate patterns in chronic distress and sleep is unclear. Studies combining the assessment of fetal movements and the determination of PMEP are planned.

Female↗

PubMed1994

[The reliability of computer-assisted long-term ECG analysis of pacemaker malfunction in patients with ventricular demand pacemakers].

The importance of the pacemaker follow-up clinic has markedly increased in the face of the currently available multiprogrammable pacemakers. In contrast to the common standard techniques in assessing pacemaker dysfunctions, Holter monitoring allows the detection of transient pace-maker dysfunctions during a long period of time. Especially computer-aided analysis provides a considerable progress, because different pacemaker dysfunctions can be detected during prolonged time periods, and--in contrast to visual analysis--a reliable survey of the real extent of transient pacemaker dysfunctions in the individual patient is assessed. The reliability of computer-aided analysis by a specially designed module was prospectively investigated in 100 consecutive patients with permanent ventricular inhibited demand pacemakers. It could be demonstrated that the positive predictive accuracy of this analysis was limited to 60.2% in detecting failures to sense and 63.2% in detecting inappropriate inhibitions, respectively. All detected failures to capture were false positive events. The positive predictive accuracy, therefore, was not calculated for this category of event. The overall positive predictive accuracy was 59.9%. In contrast, the sensitivity of computer-aided analysis was remarkably high. Possible causes of false positive and false negative findings are described. The reliability of pacemaker pulse detection was also investigated. Out of 100 analyzed Holter recordings five showed a temporary total loss of pacemaker pulses. Loss of single pacemaker pulses was found in 30 patients. False positive pacemaker pulses were seen in three patients. These results show that visual control and validation by an experienced physician are mandatory.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2003

Mathematical modelling of animate and intentional motion.

Our aim is to enable a machine to observe and interpret the behaviour of others. Mathematical models are employed to describe certain biological motions. The main challenge is to design models that are both tractable and meaningful. In the first part we will describe how computer vision techniques, in particular visual tracking, can be applied to recognize a small vocabulary of human actions in a constrained scenario. Mainly the problems of viewpoint and scale invariance need to be overcome to formalize a general framework. Hence the second part of the article is devoted to the question whether a particular human action should be captured in a single complex model or whether it is more promising to make extensive use of semantic knowledge and a collection of low-level models that encode certain motion primitives. Scene context plays a crucial role if we intend to give a higher-level interpretation rather than a low-level physical description of the observed motion. A semantic knowledge base is used to establish the scene context. This approach consists of three main components: visual analysis, the mapping from vision to language and the search of the semantic database. A small number of robust visual detectors is used to generate a higher-level description of the scene. The approach together with a number of results is presented in the third part of this article.

Computers↗

PubMed2003

Cortical inhibitory circuits in eye-movement generation.

The role inhibitory circuits play in target selection with saccadic eye movements was examined in area V1, the frontal eye fields (FEF) and the lateral intraparietal sulcus (LIP) of the Rhesus Macaque monkey by making local infusions of the GABA agonist muscimol and antagonist bicuculline. In V1, both agents greatly interfered with target selection and visual discrimination of stimuli placed into the receptive field of the affected neurons. In the FEF, bicuculline facilitated target selection without affecting visual discrimination and generated many spontaneous saccades. Muscimol in the FEF interfered with saccadic eye-movement generation. In the LIP, bicuculline was ineffective and muscimol had only a small effect. These findings suggest that in the FEF GABAergic inhibitory circuits play a central role in eye-movement generation whereas in V1 these circuits are essential for visual analysis. Inhibitory circuits in the LIP do not appear to play a central role in target selection and in visual discrimination.

Anesthetics, Local↗

PubMed2004

18F-FDG PET of gliomas at delayed intervals: improved distinction between tumor and normal gray matter.

UNLABELLED: We hypothesized that delineation of gliomas from gray matter with 18F-FDG PET could be improved by extending the interval between 18F-FDG administration and PET data acquisition. The purposes of this study were, first, to analyze standard and delayed 18F-FDG PET images visually and quantitatively to determine whether definition of tumor improved at later imaging times and, second, to investigate the dynamics of model-derived kinetic rate constants, particularly k4. METHODS: Nineteen adult patients with supratentorial gliomas were imaged from 0 to 90 min and once or twice later at 180-480 min after injection. In 15 patients, arterial sampling provided the early input function. Venous sampling provided the remaining curve to the end of the imaging sequence. Standardized uptake value (SUV) was calculated as tissue concentration of tracer per injected tracer dose per body weight. Ratios of tumor SUV relative to the SUV of gray matter, brain (including gray and white matter), or white matter were calculated at each imaging time point. Dynamic image data from tumor, gray matter, brain, or white matter were analyzed using a 2-compartment, 4-parameter model applied for the entire duration of imaging, in which delay, K1, distribution volume, k3, and k4 were optimized using a nonlinear optimization method. Parameter estimation for each region included both an early subset of data from a conventional dynamic imaging period (0-60 min) and the full, extended dataset for each region. RESULTS: In 12 of the 19 patients, visual analysis showed that the delayed images better distinguished the high uptake in tumors relative to uptake in gray matter. SUV comparisons also showed greater uptake in the tumors than in gray matter, brain, or white matter at the delayed times. The estimated k4 values for tumors were not significantly different from those for gray matter in early imaging analysis but were lower (P < 0.01) using the extended-time data. CONCLUSION: The kinetic parameter results confirm the visual and SUV interpretation that tumor enhancement is greater than enhancement of surrounding brain regions at later imaging times, consistent with a greater effect of FDG-6-phosphate degradation on normal brain relative to glioma.

Adult↗