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At least 811 records · Page 45Linked to original sources
PubMed1997

An information processing model of anxiety: automatic and strategic processes.

A three-stage schema-based information processing model of anxiety is described that involves: (a) the initial registration of a threat stimulus; (b) the activation of a primal threat mode; and (c) the secondary activation of more elaborative and reflective modes of thinking. The defining elements of automatic and strategic processing are discussed with the cognitive bias in anxiety reconceptualized in terms of a mixture of automatic and strategic processing characteristics depending on which stage of the information processing model is under consideration. The goal in the treatment of anxiety is to deactivate the more automatic primal threat mode and to strengthen more constructive reflective modes of thinking. Arguments are presented for the inclusion of verbal mediation as a necessary but not sufficient component in the cognitive and behavioral treatment of anxiety.

Anxiety↗
PubMed1999

Automatic segmentation of contours of corneal cells.

A fully automatic computerized method for segmenting contours of corneal endothelial cells is proposed. As part of the method, scale-space filtering (i.e. Gaussian filtering) is used to achieve tasks different from noise removal. This type of filtering is applied making use of the separability property of Gaussian kernels, avoiding the erosion of images. A variant of unsharp masking is used to considerably increase the visibility of dark areas of images. It is shown how the overflow that occurs when two images are subtracted can be handled to produce better results than normal unsharp masking. The method is exemplified with a low quality specular micrograph. To test the performance of the method, its output is used to automatically calculate the average cell size of images of different samples of tissue and different visual quality. The obtained results are successfully compared to those obtained with a manual semi-automatic method. A method for reading the segmented contours is suggested as well as two shape representations to achieve morphometric analysis of individual cells.

Algorithms↗
PubMed1998

Automatic influences of memory in Alzheimer's disease.

Automatic and controlled influences of memory were examined in 12 patients with early Alzheimer's disease (AD) and 12 control subjects. The subjects studied a list of words and then received three-letter word stems in three different retrieval tasks. In an indirect memory task (word-stem completion priming), they were asked to produce the first word that came to mind in response to each stem. In an inclusion task, they were required to produce a studied word in response to each stem, and in an exclusion task they were asked to produce a new, unstudied word for each stem. The performance of the subjects with AD was equal in the inclusion and exclusion conditions, showing no evidence of controlled recollection for the studied words, while their automatic memory as well as priming were preserved. The results provide neuropsychological support for the distinction between controlled and automatic memory processes.

Aged↗
PubMed1998

Controlled and automatic memory process in Alzheimer's disease.

The aim of this study was to examine the contribution of controlled (or conscious) and automatic (or unconscious) memory processes to the performance of a stem-completion recall task by persons with Alzheimer's disease and a matched group of healthy elderly individuals. The recall task made use of the process dissociation procedure of Jacoby (1991), which allows the separate estimation of conscious and unconscious influences on memory. Recollection was found to be severely impaired in the community dwelling demented patients. Further, the estimates of the automatic processing were also found to be reduced, although there was considerable overlap in the performance of the two groups on this parameter. It was found that the residual capacity of Alzheimer's patients to recall previously learned information was supported to a substantial degree by their automatic memory processes.

Activities of Daily Living↗
PubMed1990

Automatic memory processes in patients with dementia-Alzheimer's type (DAT).

We examined patients with Dementia-Alzheimer's Type, depression, and matched controls on tasks designed to compare automatic (monitoring frequency and modality) and effortful (free recall) processing of words and pictures. The results demonstrated that depressed patients performed poorly only when conditions required effortful processing, but DAT patients performed poorly under all conditions. There was almost no overlap in scores between DAT and elderly depressed patients on one of the measures of automatic processing suggesting that this measure may be clinically useful. The results suggest that automatic memory processes can be partially dissociated from effortful memory processes, but that both types of operations are impaired in DAT patients.

Aged↗
PubMed1993

Disinhibition of automatic word reading in Parkinson's disease.

The Stroop phenomenon was studied in patients with early and late onset Parkinson's disease (PD) and in normal controls to examine the effect of this disease on generating and controlling automatic mental processes. In the Stroop task subjects are presented with color or neutral words in various colors and asked to ignore the word and name its color as fast as possible. We examined the facilitory and interference effects of the irrelevant word upon naming the color by using computerized version of the Stroop test. Vocal reaction times of both early and late onset PD patients presented an augmented facilitory effect. In addition, error data of the late onset PD patients showed an enlarged interference effect. These effects are related to an impairment in the ability to control automatic-reflexive processes. The augmented facilitory effect is manifest early in the course of PD suggesting that the basal ganglia act to inhibit some automatic cognitive processes. The origin of the interference effect in late onset PD patients is less clear. It may reflect more severe basal ganglia dysfunction; or a decline in cortical inhibitory processes.

Adult↗
PubMed1997

Reliability of automatic and visual analysis of interictal spikes in lateralising an epileptic focus during video-EEG monitoring.

We evaluated 2 h of two night recordings of surface EEG of 10 patients with drug-resistant focal epilepsy using video-EEG monitoring, giving 40 h of EEG. The raw data of the automatic spike analysis according to the Gotman algorithm was visually corrected by rejecting false detections. Furthermore, the complete EEG recordings were analysed independently visually by two experienced electroencephalographers. For each method we analysed the total count of detections and the topographical distribution (left-right) of spikes. The total number of detections was significantly higher (243%) in the raw data and significantly lower after elimination of false detections (57%) in comparison to conventional analysis (100%). Lateralisation was concordant between the methods in 9/10 patients. The extent (< 75%, 75-90%, > or = 90%) was concordant in 80% between the two human raters. The automatic analysis with elimination of false detections was concordant with each of the human raters in 60% of patients. Extent of concordance was dependent of the total number of spikes with patients having more spikes being more reliably lateralised. Our results suggest that visually corrected automatic spike analysis is an economical method to use interictal epileptogenic activity as an independent indicator of the side of the epileptogenic focus in the setting of non-invasive presurgical evaluation. This is especially true in patients with many spikes.

Action Potentials↗
PubMed1998

Automatic EEG analysis during long-term monitoring in the ICU.

To assist in the reviewing of prolonged EEGs, we have developed an automatic EEG analysis method that can be used to compress the prolonged EEG into two pages. The proposed approach of Automatic Analysis of Segmented-EEG (AAS-EEG) consists of 4 basic steps: (1) segmentation; (2) feature extraction; (3) classification; and (4) presentation. The idea is to break down the EEG into stationary segments and extract features that can be used to classify the segments into groups of like patterns. The final step involves the presentation of the processed data in a compressed form. This is done by providing the EEGer with a representative sample from each group of EEG patterns and a compressed time profile of the complete EEG. To verify the above approach, 41 6 h EEG records were assessed for normality via the AAS-EEG and conventional EEG approaches. The difference between the overall assessment via compressed and conventional EEG was within one abnormality level 100% of the time, and within one-half level for 73.6% of the records. We demonstrated the feasibility and reliability of automatically segmenting and clustering the EEG, thus allowing the reduction of a 6 h tracing to a few representative segments and their time sequence. This should facilitate review of long recordings during monitoring in the ICU.

Child↗
PubMed1999

Automatic detection of epileptiform activity by single-level wavelet analysis.

We describe a new strategy to automatically identify epileptiform activity in EEG. Our scheme is based upon detecting epileptic spikes, via multiresolution analysis, a relatively new tool in signal processing, which allows for dramatic improvements in the efficiency of basic wavelet analysis. We perform a single-level analysis, which is fast and delivers satisfactory results, provided a wise strategy is adopted. Key points are: the identification of suitable wavelets, in order to gain high computational efficiency; the recognition of a proper resolution level; the computation of an appropriate dynamic threshold, in order to pick out the pathological events. Using a suitable wavelet as the model of a threshold-event proved to be a good choice for devising an algorithm which efficiently performs automatic analysis at high-sensitivity levels. The proposed algorithm was implemented into a C++ multiplatform code having an user-friendly interface, which runs on general-purpose PCs. Results obtained on a set of test tracings, show that the sensitivity of the automatic analysis can be as high as 96%, while less than 5% of the overall recording time is marked. The computational complexity of our algorithm is O (N). Its highly efficient implementation allows for the analysis of up to 310 s of 8 channel EEG, by spending one mere CPU second on a standard PC.

Algorithms↗
PubMed1996

Deficiencies of automatic endoscopic reprocessors: a method to achieve high-grade disinfection of endoscopes.

BACKGROUND: We show that disinfection using the automatic endoscopic reprocessor is not complete and propose a method for high-grade disinfection of endoscopes. METHODS: We used an automatic endoscopic reprocessor, Pyser System 83, and 2% glutaraldehyde. After each endoscopic procedure, the endoscopes were divided into three groups. Endoscopes in group A were washed only by the reprocessor. Group B endoscopes were washed by the reprocessor after the connectors were soaked in glutaraldehyde for 5 minutes. The channels, valves, connecting sections of group C endoscopes, and the connectors of the machine were sprayed with glutaraldehyde before machine-washing. Swabs were taken from all 13 parts of each endoscope and machine for microbiologic culture. RESULTS: Six endoscopes were positive, cumulatively, for bacterial contamination in group A. Among group B endoscopes, one remained contaminated. No endoscope was positive in group C. The difference between group A and C was statistically significant (p < .05). CONCLUSIONS: Machine washing by automatic endoscopic reprocessors may not achieve complete disinfection. Additional procedures are necessary. High-grade disinfection of the connectors is critical. Disinfection of the interface between the connectors is important.

Disinfection↗
PubMed2004

A VxD-based automatic blending system using multithreaded programming.

This paper discusses the object-oriented software design for an automatic blending system. By combining the advantages of a programmable logic controller (PLC) and an industrial control PC (ICPC), an automatic blending control system is developed for a chemical plant. The system structure and multithread-based communication approach are first presented in this paper. The overall software design issues, such as system requirements and functionalities, are then discussed in detail. Furthermore, by replacing the conventional dynamic link library (DLL) with virtual X device drivers (VxD's), a practical and cost-effective solution is provided to improve the robustness of the Windows platform-based automatic blending system in small- and medium-sized plants.

Algorithms↗
PubMed2000

The mesh-matching algorithm: an automatic 3D mesh generator for finite element structures.

Several authors have employed finite element analysis for stress and strain analysis in orthopaedic biomechanics. Unfortunately, the definition of three-dimensional models is time consuming (mainly because of the manual 3D meshing process) and consequently the number of analyses to be performed is limited. The authors have investigated a new patient-specific method allowing automatically 3D mesh generation for structures as complex as bone for example. This method, called the mesh-matching (M-M) algorithm, generated automatically customized 3D meshes of anatomical structures from an already existing model. The M-M algorithm has been used to generate FE models of 10 proximal human femora from an initial one which had been experimentally validated. The automatically generated meshes seemed to demonstrate satisfying results.

Algorithms↗
PubMed2002

Computer-assisted automatic peak recognition and result evaluation for analysis of chlorinated hydrocarbons in environmental samples.

A data manipulation method has been developed for automatic peak recognition and result evaluation in the analysis of organic chlorinated hydrocarbons with dual-column gas chromatography. Based on the retention times of two internal standards, pentachlorotoluene and decachlorobiphenyl, the retention times of chlorinated hydrocarbons can be calibrated automatically and accurately. It is very convenient to identify the peaks by comparing the retention times of samples with the calibrated retention times calculated from the relative retention indices of standards. Meanwhile, with a suggested two-step evaluation method the evaluation coefficients and the suitable quantitative results of each component can be automatically achieved for practical samples in an analytical system using two columns with different polarities and two internal standards.

Automation↗
PubMed1994

Automatic detection of spatial and dynamic heterogeneity of repolarization.

Heterogeneity of ventricular repolarization is associated with the development of life-threatening ventricular arrhythmias. Temporal heterogeneity of repolarization may be manifest in an individual beat (spatial heterogeneity) or in a sequence of beats (dynamic heterogeneity). Spatial inhomogeneity of repolarization throughout the myocardium may be expressed electrocardiographically as dispersion of repolarization durations computed in simultaneously recorded leads. The beat-to-beat changes in the repolarization pattern (duration and/or amplitude) may account for a dynamic (time-dependent) dimension of heterogeneity, occasionally seen as T-wave alternans. A visual detection of heterogeneous repolarization is a time-consuming, observer-dependent, and frequently inaccurate process. Therefore, we developed computer algorithms designed to detect automatically (1) dispersion of repolarization and (2) nonvisible T-wave alternans from digitally recorded (1,000 Hz) X, Y, and Z electrocardiogram leads. This automatic approach was subsequently tested in 10 patients with idiopathic long QT syndrome and in 10 age-matched normal subjects. Long QT syndrome patients presented with significantly higher indices of heterogeneity in comparison with the control subjects; the dispersion of repolarization was 44 +/- 11 and 13 +/- 6 ms, respectively (P < .01), and T-wave alternans index was 0.40 +/- 0.37 and 0.03 +/- 0.06, respectively (P < .01). Simultaneous evaluation of spatial (dispersion of repolarization) and dynamic (T-wave alternans) aspects of repolarization provides new insight into heterogeneity of electrical recovery after myocardial depolarization. The automatic detection of repolarization dispersion and T-wave alternans in digital electrocardiogram recordings provides a practical method to evaluate heterogeneity of repolarization and may be useful for stratifying patients at risk of ventricular arrhythmias.

Arrhythmias, Cardiac↗
PubMed2003

Intentional and automatic measures of specific-category effect in the semantic impairment of patients with Alzheimer's disease.

The breakdown of semantic knowledge relative to living and non-living categories was studied in patients with Alzheimer's disease (AD). The same living and non-living items were used in a semantic battery and in a semantic priming paradigm exploring automatic access to the semantic system. Although AD patients showed a semantic deficit on the intentional semantic battery, they demonstrated normal semantic facilitation on the priming task. In the AD group as a whole, the semantic impairment did not preferentially affect the living category either in the intentional or automatic condition. Instead, a prevalent deficit for the living category was found in three AD patients (14% of the group) on the intentional semantic tasks, but not on the automatic one. These findings support the view that the category effect may not be a generalised phenomenon in AD but may be restricted to a limited number of patients. The intentional/automatic dissociation of the semantic breakdown demonstrated by AD patients is discussed in relation to different theories regarding the organisation of semantic memory.

Aged↗
PubMed1998

Categorical priming in the cerebral hemispheres: automatic in the left hemisphere, postlexical in the right hemisphere?

Automatic and postlexical semantic processing in the cerebral hemispheres was studied by presenting categorically related but nonassociated word pairs (e.g., TABLE-BED) to the left visual field (LVF) or to the right visual field (RVF) in semantic priming experiments. Experiment 1 examined automatic priming across stimulus onset asynchronies (SOAs) of 165 and 750 ms with a low proportion of related pairs and a low nonword ratio, employing a GO-NOGO lexical decision task. In contrast to an earlier view that a larger range of meanings is automatically activated in the right than in the left hemisphere, priming was observed in the RVF/left hemisphere only. SOA did not exert any effects. In Experiment 2, postlexical semantic matching of the prime and the target was encouraged by requiring subjects to respond to both of them at the same time. Now there was priming in the LVF, suggesting that a postlexical matching process works in the right hemisphere. The earlier studies showing a right hemisphere advantage in categorical priming are reinterpreted according to the postlexical right hemisphere hypothesis.

Adult↗
PubMed2001

Human and automatic face recognition: a comparison across image formats.

Human subjects perform poorly at matching different images of unfamiliar faces. When images are taken by different capture devices (cameras), matching is difficult for human perceivers and also for automatic systems. We test an automatic face recognition system based on principal components analysis (PCA) and compare its performance with that of human subjects tested on the same set of images. A number of variants of the PCA system are compared, using different matching metrics and different numbers of components. PCA performance critically depends on the choice of distance metric, with a Mahalanobis metric consistently outperforming a Euclidean metric. Under optimal conditions, the automatic PCA system exceeds human performance on the same images. We hypothesise that unfamiliar face recognition may be mediated by processes corresponding to rather simple functions of the inputs.

Face↗
PubMed2000

Automatic morphometry of nerve histological sections.

A method for the automatic segmentation, recognition and measurement of neuronal myelinated fibers in nerve histological sections is presented. In this method, the fiber parameters i.e. perimeter, area, position of the fiber and myelin sheath thickness are automatically computed. Obliquity of the sections may be taken into account. First, the image is thresholded to provide a coarse classification between myelin and non-myelin pixels. Next, the resulting binary image is further simplified using connected morphological operators. By applying semantic rules to the zonal graph axon candidates are identified. Those are either isolated or still connected. Then, separation of connected fibers is performed by evaluating myelin sheath thickness around each candidate area with an Euclidean distance transformation. Finally, properties of each detected fiber are computed and false positives are removed. The accuracy of the method is assessed by evaluating missed detection, false positive ratio and comparing the results to the manual procedure with sampling. In the evaluated nerve surface, a 0.9% of false positives was found, along with 6.36% of missed detections. The resulting histograms show strong correlation with those obtained by manual measure. The noise introduced by this method is significantly lower than the intrinsic sampling variability. This automatic method constitutes an original tool for morphometrical analysis.

Animals↗