PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Computer Graphics”

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

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

At least 1,189 records · Page 66Linked to original sources
PubMed1988

Escape behavior in the cockroach: distributed neural processing.

Escape reactions are often considered to be among the simplest behaviors. The nerve circuits guiding these reactions are also generally thought to be simple. For instance, in several species a single interneuron is sufficient to trigger normal escape. The evasive response of the cockroach, however, appears to be more complex both behaviorally and physiologically. In this review, several complications of the behavior are pointed out, based on a recent computer-graphic analysis of the leg movements. Next described is the cooperative role of several interneurons--not just one--in evoking an escape turn away from the stimulus. A model of this multicellular code for stimulus direction is then presented that correctly predicts the turning behavior under many different experimental conditions. Finally, an overall scheme of the information processing for escape behavior is presented.

Animals↗
PubMed1987

The structural evolution of cobra venom cytotoxins.

In order to analyze the evolutionary behavior of the cobra venom cytotoxins, their probable tertiary structure was predicted using computer graphics. The 41 amino acid sequences known show that the major evolutionary changes have taken place in two particularly exposed areas of the molecular surface. In each area, neighboring residue positions seem to have evolved interdependently, but there is no obvious interdependence between the two areas. Indeed, the relative evolution of these two areas prompts a subdivision of the sequence set into four groups. According to the known cytotoxin circular dichroism spectra, one of these four groups could be characterized by a difference in molecular secondary structure. Since the two variable areas have functional associations, it is suggested that their evolution may be governed by a target with several similar binding sites.

Amino Acid Sequence↗
PubMed1989

Three-dimensional model of the insect-directed scorpion toxin from Androctonus australis Hector and its implication for the evolution of scorpion toxins in general.

The three-dimensional structure of the insect-directed toxin from the scorpion Androctonus australis Hector has been modelled using computer graphics and energy-minimization techniques. The model-building procedure was based on the known high resolution structures of two scorpion toxins of different types: toxin II from A. australis Hector, an alpha-toxin, and variant 3 from Centruroides sculpturatus Ewing that belongs to the beta-toxin structural group. Although the insect-directed toxin has one atypical disulfide bridge, the general structural features of the scorpion toxin family, including the presence of a "conserved-hydrophobic" surface, seem to be well-conserved. However, the orientation and length of some loops and regions thought to be important for toxicity are different for alpha-toxins, beta-toxins, and the insect-directed toxin. Thus, the binding of a scorpion toxin to its site on the Na+ channel seems to be based on (1) the presence of a surface containing a series of conserved and/or hydrophobic residues, more or less common to all these molecules, and (2) an adjacent area that modulates the specificity of the interaction.

Amino Acid Sequence↗
PubMed1994

[Morphometric studies on the fetal development of the human mandible].

Serial sections of eleven human mandibles of embryos and fetuses ranging in size from 18 mm CRL to 66 mm CRL were computer-graphically reconstructed. The extension of the Meckel cartilage and the mandibular bony structures were morphometrically studied. In emphasis the study encompassed measurements portraying length, width, dorsal opening angle, and the position of the mental foramen. In addition five mandibles of human embryos and fetuses with a size range between 30 and 50 mm CRL were radiographically examined. Results showed that in the younger specimens between 21 and 29 CRL size development of the structures of the mandible and the development of overall fetal body size take place independently from each other. During further development a change in the form of the mandible from a wide V over an acute V to a more rounded U form was observed.

Cartilage↗
PubMed1991

Segmental differences in the stability of the trp-repressor peptide backbone.

Exchange lifetimes of amide protons in trp-repressor with and without the corepressor, L-tryptophan, were studied by heteronuclear 2D NMR spectroscopy. The amide proton exchange times revealed pronounced differences in the stability of different regions of the trp-repressor. The dimeric core of the molecule is relatively compact and homogeneous in terms of the measured parameters in both apo- and holorepressors. On the other hand the DNA-binding region appears less stable and more susceptible to the exchange of its backbone protons with the solvent. The NMR findings reported here are consistent with and amplify information on the stability of the trp-repressor obtained by other methods.

Amino Acid Sequence↗
PubMed1995

Medical applications of virtual reality.

Medical applications for virtual reality (VR) are just beginning to emerge. These include VR surgical simulators, telepresence surgery, complex medical database visualization, and rehabilitation. These applications are mediated through the computer interface and as such are the embodiment of VR as an integral part of the paradigm shift in the field of medicine. The Green Telepresence Surgery System consists of two components, the surgical workstation and remote worksite. At the remote site there is a 3-D camera system and responsive manipulators with sensory input. At the workstation there is a 3-D monitor and dexterous handles with force feedback. The VR surgical simulator is a stylized recreation of the human abdomen with several essential organs. Using a helmet mounted display and DataGlove, a person can learn anatomy from a new perspective by 'flying' inside and around the organs, or can practice surgical procedures with a scalpel and clamps. Database visualization creates 3-D images of complex medical data for new perspectives in analysis. Rehabilitation medicine permits impaired individuals to explore worlds not otherwise available to them, allows accurate assessment and therapy for their disabilities, and helps architects understand their critical needs in public or personal space. And to support these advanced technologies, the operating room and hospital of the future will be first designed and tested in virtual reality, bringing together the full power of the digital physician.

Computer Graphics↗
PubMed1995

A quantitative color recognition measurement system using multimedia computer environment.

We developed a quantitative measurement system that tests the degree of dysgnosia resulting from Obsessive-Compulsive Disorder (OCD). The system outputs a stimulation word that had been set in advance using the voice output facility of the personal computer, then displays a color chart and waits for input from the subject. When the subject touches the CRT screen or clicks the mouse, the system records the response time and coordinates of input position. There were 30 stimulation words in the system. After 30 measurements of response time and input coordinates, the system outputs a results file that includes each response time and input coordinates. This test is easier and simpler than other psychological tests such as MMPI. The influence of the examiner can be reduced to the minimum with this system because it is a computer-based automatic measurement system. To use the computer system, an examiner can easily standardize the environment of the illumination, etc. Moreover, the system can save labor in testing, and can manage large amounts of data easily using the file management facility.

Association↗
PubMed1999

Colonoscopy aided by magnetic 3D imaging: assessing the routine use of a stiffening sigmoid overtube to speed up the procedure.

There are not enough trained colonoscopists to cope with the present recommended number of examinations required for diagnostic and surveillance purposes. If colorectal cancer screening is to be introduced, endoscopic examination of the large bowel needs to be easier to learn and significantly quicker to carry out. The 'Bladen system', first described in 1993, is a non-radiological method of visualising the path of the endoscope, using magnetic drive coils under the patient and a chain of sensors along the biopsy channel of the instrument. In 1998, results were published using a novel computer graphics system (the RMR system), in which a much more realistic image of the endoscope could be produced using the stored positional data from the Bladen system. The RMR system has been further refined to allow, for the first time ever, accurate measurement of the effect of the passage of a colonoscope along the bowel on the lengths of different segments of the large intestine. The results obtained in 232 patients undergoing colonoscopy are analysed. In 77 of the patients, a stiffening overtube is used to splint the sigmoid colon once the endoscope is at or beyond the splenic flexure. The mean time taken to pass the colonoscope across the transverse colon is significantly shorter (p < 0.001) when an overtube is used, despite it resulting in significant lengthening of the transverse colon. The routine use of a stiffening overtube can be expected to reduce the total procedure time by between 10 and 20%.

Adult↗
PubMed1986

[Calculation of the true angle in malposition of the skeletal system using electronic data processing. Retrospective study of 53 axis deviations in healed femoral fractures].

Under standard conditions deformations in the skeletal system are diagnosed by two X-ray photographs whose planes of projection form a right angle. The degree of deviation from the axis is measured directly on the X-ray photograph with a protractor. The analysis of the position of the axis of a tabular bone is carried out by determining the varus/valgus or ante/recurvation deformities resp. in the a.-p. and lateral rays. The degree of deformation is expressed through the supplementary angle. We asked ourselves whether a diagnostic procedure using X-rays taken in two planes is suitable for substantiating the evidence of a deformation of the axis. Example: If a fracture of the lower leg shows a varus deformity of 20 degrees in the a.-p. and a normal position of the axis in the lateral photograph, the actual angle is 20 degrees. This situation is an expection in that most cases the defect of the axis is a so-called combined defect (dislocation from the axis in both planes). In this case it can maintained that the measurable angle of deviation in the a. -p. and lateral X-ray photographs is smaller than the angle that is actually included by both fragments. We call this angle true angle. If you think of a fractured tubular bone as a cylinder it can be shown in a diagram that its deformation can only occur in one plane (Figure 1). Only from the perspective of a ray falling vertically on the curve k we would be able to determine the true angle directly from the photograph with a protractor.(ABSTRACT TRUNCATED AT 250 WORDS)

Casts, Surgical↗
PubMed1992

[Visualized three-dimensional reconstruction and image analysis in orthopedics and trauma surgery].

Computer tomography is a commonly used technique for detecting pathological alterations in soft tissue and the skeleton. The remote access to image informations as well as the allocation of display and processing tools via networks enables improved diagnostic and therapeutic practice in orthopaedic and traumatologic surgery. The realization of a user friendly image analysis system displays and processes the acquired images in a modality oriented manner. Our method is based on a unique file format and specific evaluation procedures to produce the input data for three-dimensional display and algorithms for the individual design of implants. Our image analysis system can process the data of conventional computer tomographies with three or more mm distance. In contrast to the available systems there is a low significance of radiation effects.

Computer Graphics↗
PubMed2004

Multiple descriptions based wavelet image coding.

We present a simple and efficient scheme that combines multiple descriptions coding with wavelet transform under JPEG2000 image coding architecture. To reduce packet losses, controlled amounts of redundancy are added to the wavelet transform coefficients to produce multiple descriptions of wavelet coefficients during the compression process to produce multiple descriptions bit-stream of a compressed image. Even if a receiver gets only parts of descriptions (other descriptions being lost), it can still reconstruct image with acceptable quality. Specifically, the scheme uses not only high-performance wavelet transform to improve compression efficiency, but also multiple descriptions technique to enhance the robustness of the compressed image that is transmitted through unreliable network channels.

Algorithms↗
PubMed2004

Image segmentation based on Mumford-Shah functional.

In this paper, the authors propose a new model for active contours segmentation in a given image, based on Mumford-Shah functional (Mumford and Shah, 1989). The model is composed of a system of differential and integral equations. By the experimental results we can keep the advantages of Chan and Vese's model (Chan and Vese, 2001) and avoid the regularization for Dirac function. More importantly, in theory we prove that the system has a unique viscosity solution.

Algorithms↗
PubMed1987

A microcomputer implementation of status and alarm algorithms in a cardiac surgical intensive care unit.

Algorithms have been developed for monitoring the cardiovascular status of patients on their return to an intensive care unit after cardiac surgery and also for giving an immediate alarm of a critical deterioration in this status. The two systems for implementing these algorithms were initially developed on Z80 based microprocessor systems and preliminary clinical trials based on the resulting instruments proved encouraging. For further clinical trials of the algorithms the systems have been integrated and implemented on a BBC microcomputer with a 6502 second processor. The development and structure of the programs for implementing the algorithms are described, together with the program input and output facilities and diagnostic techniques used to analyse the information output from the program.

Algorithms↗
PubMed1996

A human friendly reporting and database system for brain PET analysis.

We have developed a human friendly reporting and database system for clinical brain PET (Positron Emission Tomography) scans, which enables statistical data analysis on qualitative information obtained from image interpretation. Our system consists of a Brain PET Data (Input) Tool and Report Writing Tool. In the Brain PET Data Tool, findings and interpretations are input by selecting menu icons in a window panel instead of writing a free text. This method of input enables on-line data entry into and update of the database by means of pre-defined consistent words, which facilitates statistical data analysis. The Report Writing Tool generates a one page report of natural English sentences semi-automatically by using the above input information and the patient information obtained from our PET center's main database. It also has a keyword selection function from the report text so that we can save a set of keywords on the database for further analysis. By means of this system, we can store the data related to patient information and visual interpretation of the PET examination while writing clinical reports in daily work. The database files in our system can be accessed by means of commercially available databases. We have used the 4th Dimension database that runs on a Macintosh computer and analyzed 95 cases of 18F-FDG brain PET studies. The results showed high specificity of parietal hypometabolism for Alzheimer's patients.

Alzheimer Disease↗
PubMed1995

Three-dimensional display of cardiac structures using reconstructed magnetic resonance imaging.

It is sometimes difficult to understand the three-dimensional (3D) relationship of cardiac and mediastinal structures despite advances in magnetic resonance (MR) imaging techniques. We present a low-cost system for 3D reconstruction of the major mediastinal structures by processing the MR imaging data on a NeXT workstation. MR images of multisection, multiphase, spin-echo techniques stored in a picture archiving and communication system (PACS) data base were used for the reconstruction. The computer program obtained the contours of the multiple components of the mediastinal structures by the combination of automatic and manual procedure. The bundled software of a 3D kit was used for surface rendering of hidden surface removal, shading of the visible parts of the surfaces, perspective transformation, and motion parallax by rotation of the surfaces. 3D reconstruction was performed in 15 patients with cardiac diseases, and the 3D-reconstructed images were compared with the plain chest x rays of the patients. The 3D presentation clearly showed the complex anatomy of cardiovascular diseases and helped elucidate the misconceptions in the interpretation of the plain chest x rays. Our 3D images are used for education and should be viewed by medical students and beginners in radiology at an individual pace with plain chest radiographs, MR images, and legends. Although applied to the heart and the great vessels in this report, this system is also applicable to other structures.

Computer Graphics↗
PubMed1994

Desktop publishing and medical imaging: paper as hardcopy medium for digital images.

Desktop-publishing software and hardware has progressed to the point that many widely used word-processing programs are capable of printing high-quality digital images with many shades of gray from black to white. Accordingly, it should be relatively easy to print digital medical images on paper for reports, instructional materials, and in research notes. Components were assembled that were necessary for extracting image data from medical imaging devices and converting the data to a form usable by word-processing software. A system incorporating these components was implemented in a medical setting and has been operating for 18 months. The use of this system by medical staff has been monitored.

Computer Graphics↗