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At least 703 records · Page 39Linked to original sources
PubMed1984

An interactive microcomputer-based graphics system for analysis of cardiodynamic function.

An on-line interactive, modular, menu-driven microcomputer-based data acquisition and analysis system was designed and implemented. This system includes a low-cost commercial desk-top graphics computer with a modular construction. All these operations are performed using extended BASIC "CALL" statements. The system is designed to be used in a cardiovascular research and laboratory environment where the assessment of hemodynamic and cardiodynamic function includes routine measurements of pressure and flow. In addition, the measurement of regional and global left ventricular chamber dimensions have been implemented. The modular design of the software system is "human-engineered" to enable a simple, cost effective computer system to perform physiological measurement and control. Extended BASIC language instructions provide the casual computer user with a simple yet effective means of implementing on-line data acquisition, analysis and graphic production and display.

Cardiovascular Physiological Phenomena↗
PubMed1999

New evidence from Le Moustier 1: computer-assisted reconstruction and morphometry of the skull.

In this study, we present a new computerized reconstruction of the Le Moustier 1 Neanderthal skull and discuss its significance for Neanderthal growth and variability. Because of the precarious state of preservation of the original material, we applied entirely noninvasive methods of fossil reconstruction and morphometry, using a combination of computed tomography, computer graphics, and stereolithography. After electronic restoration, the isolated original pieces were recomposed on the computer screen using external and internal anatomical clues to position the bone fragments and mirror images to complete missing parts. The inferred effects of general compressive deformation that occurred during fossilization were corrected by virtual decompression of the skull. The resulting new reconstruction of the Le Moustier 1 skull shows morphologic features close to the typical Neanderthal adult state. Residual asymmetry of skeletal parts can be traced to in vivo skeletal modification: the left mandibular joint shows signs of a healed condylar fracture, and the anatomy of the occipital region suggests mild plagiocephaly. Using micro-CT analysis, the left incus could be recovered from the matrix filling of the middle ear cavity. Its morphometric dimensions are similar to those of the La Ferrassie III incus. The morphometric characteristics of the inner ear deviate substantially from the condition reported as typical for Neanderthals and fall within the range of modern human variability.

Animals↗
PubMed1976

Computer visualization of flow patterns for prosthetic heart valves.

Flow patterns for commonly used aortic valve prostheses were formed with the aid of fluid dynamics equations, numerical analysis techniques and computer graphics. Simulations of velocities, vorticity, pressure and certain stress values were developed by a computer and displayed for man-machine interaction. The ball, disc and tilting-disc occluders were of interest. The displays comprised both contour and perspective patterns; the latter permitting semi-quantitative evaluation of particular parameters. Comparisons between the computer simulations and those flow visualizations formed by Björk and co-workers were assessed. Although the methodology was of prime concern for presentation, the capability of the tilting-disc prosthesis for presenting a more natural flow regime was shown. Thoughts of future studies were entertained.

Aortic Valve↗
PubMed1977

Vector cardiographic assessment of implanted cardiac pacemakers.

The design and use of an on-line PDP 11/40 based vector cardiographic pacemaker assessment system is described. The system has been designed for comprehensive, automated testing of either fixed rate or demand implanted cardiac pacemakers. It is accurate and can be operated by a laboratory assistant without special training. Pacemaker parameters extracted are pulse height, width, rate, energy index and the frontal plane vector length and angle at maximum inspiration and during quiet breathing. In addition, a graphical representation of the patient's ECG and the pacemaker pulse is obtained on a computer graphics terminal. Patient data are written to cartridge disk for permanent record following the test. At each subsequent test of the implanted pacemaker, the data on disk are addended with the latest quantitative results. A separate off-line FORTRAN program can interrogate disk files for detailed analysis of patient data and display of parameter trends since implantation.

Computers↗
PubMed2002

A mathematical formula to calculate the theoretical range of motion for total hip replacement.

The reduced range of motion (ROM) resulting from total hip replacement (THR) leads to frequent prosthetic impingement, which may restrict activities of daily living and cause subluxation and dislocation. Therefore, to know the ROM of THR is very important in clinical situations and in the design of prostheses. THR involves a pure ball and socket joint. We created a mathematical formula to calculate the theoretical ROM of THR limited by the prosthetic impingement. The ROM of THR is governed by the following five factors, (1) The prosthetic ROM (oscillation angle: obtained from company data), (2) cup abduction (3) cup anterior opening, (4) the angle of the femoral neck component from the horizontal plane, and (5) the femoral neck anteversion. The last 4 factors are able to be obtained from anterior-posterior, axial X-rays and CT of the patient's THR. The objective was to create mathematical formulas that could accurately and quickly calculate the ROM of THR. By entering the five values into a computer programmed with the formulas, one could obtain the ROM for the THR. This reveals the effect on ROM of the oscillation angle and the interaction of ROM with cup abduction, anterior opening and neck anteversion. Furthermore this readily would enable a clinical evaluation of the possibility of postoperative dislocation and help in postoperative rehabilitation. The calculated numerical values of ROM by these mathematical formulas were successfully compared with the ROMs obtained from 3-dimensional computer graphics (3D-CG).

Biomechanical Phenomena↗
PubMed1986

Interactive display of three-dimensional radionuclide distributions.

Tomographic images of three-dimensional radionuclide distributions are usually presented as a set of parallel planar slices. A technique has been developed to enable the observer to perceive directly the three-dimensional morphology of the activity distribution by displaying iso-count surfaces. Computer graphics techniques have been used to present shaded surface images using a conventional nuclear medicine computer system. Because of the relatively coarse spatial sampling of radionuclide tomograms, a smooth shading algorithm based on a local polynomial fit procedure was developed. By using a simple solid model approach for data storage the program executes interactively, allowing the observer to view the reconstructed activity distribution from any aspect. The technique has been successfully applied to radionuclide tomograms of several organs, and promises to be particularly useful for the display or cardiac blood pool data.

Algorithms↗
PubMed1997

[Puerperal infection. Analysis of 618 cases].

From September 1993 to March 1995 a prospective, descriptive study was performed at Obstetrical Department of the General Hospital 2A the Mexican Institute of Social Security. An attempt to know the real puerperal infection incidence in our own hospital to be able to make hypothesis and take specific measures in puerperal infection control. Dairy account of interesting data of cases under inclusion criteria. Entering data in personal computer. Graphics and analysis were accomplished using Lotus 123, Statgraphics, EPI-6 of CDC and Freelance computational programs. Search of central tendency measures were performed, (media, median, mode, standard deviation). Odds ratio and relative risk were calculated, including hospitalization time and its temporary variation to data cross. X square and pi were including hospitalization time and its temporary variation to data cross. X square and pi were determined to statistic validates. The cumulated rate of general puerperal infection were 1.2%. By stratification, the cumulated rate of infection after cesarean section, vaginal delivery and miscarriage were 5.4%, 0.8% and 0.3%, respectively. There was predominance of infection after cesarean section, over infection after vaginal delivery and after miscarriage. (monthly media of 24.6, 7.3 and 0.47, respectively). The puerperal infection was present principally in primiparous and in patients with one previous cesarean section. The patients in which the termination of pregnancy was by cesarean section, (0.015 infection cumulated incidence), had an infection risk 5.76 and 18.66 times greater than the patients with vaginal delivery and miscarriage. (Relative risk of 6.76 and 19.66) The site of puerperal infection was implicated in combinations or isolated, under nine clinical situation. The five most frequent clinical situation, between these nine, in incidence order from major to minor were the following: Endometritis alone, Endometritis combined with wound abscess. Endometritis with urinary infection, complicated endometritis, (sub vesical abscess, parametritis, peritonitis, salpingitis), and wound abscess alone). The greater hospitalization time was present in cases of complicated endometritis followed by wound abscess alone or combined. Complicated endometritis, (incidence 0.0010), compel us to hysterectomy in 15 cases. No death was registered among the patients with puerperal infection studied.

Adult↗
PubMed1982

A simplified method for computer analysis of autoradiograms from two-dimensional gels.

A simple method is described for computer analysis of a discrete number of spots on autoradiograms from two-dimensional gels. The method involves digitizing the density data on an autoradiograph with a rotating drum densitometer and displaying the data on a graphics computer terminal. The software allows the operator to select the boundaries of the spots to be analyzed from the terminal, then integrates the the density of the spots and tabulates the data. Graphics options allow the operator to display a computer-generated image of the area of the film being analyzed. Accurate integration of weak or overlapping spots is accomplished by a nonlinear least squares fit of the density data to normal Gaussian curves in the x and y dimensions followed by analytical integration of the equations. Since the software is written in Fortran IV and the equipment required to run the programs is available in most computing centers, this technique should allow laboratories of modest resources to quantitate information from two-dimensional gels.

Animals↗
PubMed1991

The use of graphic design in an interactive computer teaching program.

The widespread diffusion of affordable computers into the scientific and educational community has provided the opportunity to design medical and scientific teaching programs illustrated either by hand or by utilizing commercially available software and manipulating existing computer generated images. The medical illustrator can provide the ideal aesthetic link between text format information and the visual representation of such knowledge in a concise presentation format. The availability of interactive multimedia programs has given the medical illustrator an environment to create and enhance Hypermedia designed specifically for the purpose of medical education. This paper will focus on the incorporation of illustration and screen design into "CT The Game," an experimental medical teaching program currently being developed in the Johns Hopkins Body CT Imaging Laboratory. The program is designed to provide an enjoyable approach to learning Computed Tomography (CT), and is directed toward an audience of medical students, residents, and fellows.

Computer Graphics↗
PubMed1985

Three-dimensional distribution of neuromuscular junctions in human cricothyroid.

Microinjections of myoneural blocking agents are effective in the treatment of strabismus and have been proposed as a possible technique to treat spastic dysphonia. The success of such a technique would rely on a precise knowledge of the neuromuscular junction distribution in the laryngeal muscle to be injected. In view of the possibility of an involvement of the cricothyroid muscle in spastic dysphonia or other neuromuscular disorders, we determined the three-dimensional distribution of neuromuscular junctions in the human cricothyroid muscle. Cricothyroid muscles obtained from autopsy cases were fixed, sectioned, and processed for the histochemical localization of neuromuscular junction acetylcholinesterase. Using serial sections and a computer interfaced X-Y digitizer, the neuromuscular junctions were referenced to various anatomic landmarks and the neuromuscular junction distribution and reconstructed in three dimension using computer graphics.

Computers↗
PubMed1989

A study on continuous follow-the-leader (FTL) gaits: an effective walking algorithm over rough terrain.

The follow-the-leader (FTL) gait is an effective walking algorithm for a legged system to traverse a rough terrain. In an FTL gait, all the legs simply place at the footprints made by the legs ahead of them. By this way the demand on foothold selection is significantly reduced. A special category of FTL gaits, called continuous FTL gaits, provide a smooth body motion during walking and enable the legged system to reach a higher speed. In this paper, a comprehensive study of continuous FTL gaits is presented. The equations for two types of continuous FTL gaits are formulated. The stability of these continuous FTL gaits is studied analytically and verified numerically. Strategies of forbidden area avoidance and special methods of large foot adjustment are introduced. The motion resulting from the use of these strategies and methods is simulated and checked using computer graphics.

Algorithms↗
PubMed1990

Estimation of the age of an individual based on times of eruption of permanent teeth.

This is a community based study of the times of eruption of permanent teeth to establish the age of an individual. The study is based on dental examination of 1008 subjects in the age group 5-14 years, residing in Tirupati, Andhra Pradesh, India. The median age of eruption was computed based on the concept of "Ex" which is defined as the age at which a specified percentage of individuals show eruption of a given permanent tooth. The median age "E50" was computed by transformation of percentages to probits and plotting a graph between age and probits. E50 was computed graphically corresponding to a probits value of 5.0 or 50%. A mathematical regression equation [Kusri's] was computed for each graph. The age of an individual can be computed based on the E50 value of the permanent tooth which erupted last. The probability of the given individual being above or below the assessed age can be estimated by referring to graph and probit transformation table.

Adolescent↗
PubMed2004

Virtual reality exposure therapy of anxiety disorders: a review.

Virtual reality exposure therapy (VRET) is an altered form of behavioral therapy and may be a possible alternative to standard in vivo exposure. Virtual reality integrates real-time computer graphics, body tracking devices, visual displays, and other sensory input devices to immerse patients in a computer-generated virtual environment. Research on this type of treatment for anxiety disorders is discussed in this article, and the mediating and moderating variables that influence VR treatment effectiveness as well. Evidence is found that VRET is effective for participants with fear of heights and of flying. For other phobias, research to date is not conclusive. More randomized clinical trials in which VRET is compared with standard exposure are required. Furthermore, studies are needed in which VRET is not just a component of the treatment package evaluated, but in which VRET should be assessed as a stand-alone treatment.

Anxiety Disorders↗
PubMed1999

Three-dimensional artifact induced by projection weighting and misalignment.

In recent years, the use of computer graphic techniques to produce three-dimensional (3-D) and reformatted images from a set of axial computed tomography (CT) images has gained significant interest. In most cases, the CT images are generated with the projection data set weighted prior to reconstruction, to combat motion artifacts, data inconsistency, or redundant data samples. In this paper, we investigate the potential bias introduced to the reconstruction as a result of the interaction of the projection weights and the isocenter misalignment (ISM). We demonstrate that when the weights applied to the conjugate rays are significantly different, bias will result which favors the sample with a higher weight. Although the error is not easily detected in axial CT images, it can be quite visible in 3-D or multiplanar reformatted (MPR) images. In this paper, we first present a theoretical framework to analyze and predict the bias. The theoretical prediction is validated by both computer simulations and phantom experiments. Several schemes to combat this artifact are subsequently presented; and their effectiveness is demonstrated.

Artifacts↗
PubMed1991

The computerized pupil.

An IBM-compatible computer graphics software program has been developed which simulates pupillary function. A light pen, electronically interfaced with the computer, simulates a pen light and, when it is placed on the computer image of the pupil, causes pupillary constriction; when it is withdrawn, the pupils redilate. A variety of abnormal pupillary responses are depicted. Anatomical diagrams and questions concerning various simulated pupillary conditions further enhances the educational experience. Medical students, residents in ophthalmology and the neurosciences, optometrists, nurses, ophthalmic assistants, and other health care professionals can utilize this program to learn a wide range of pupillary abnormalities in an interactive environment.

Audiovisual Aids↗
PubMed1988

Computer-generated diagnostic correction of anterior diastemas.

A technique for pretreatment estimation of appearance following cosmetic change to the anterior teeth by using a computer-generated image has been described. Patients should be advised that the generated projection is an estimation. As with a diagnostic set-up, a computer-generated result can only approximate final treatment. The patient must understand that the result could vary for reasons that might include (1) restorative material, (2) functional occlusal needs, (3) gingival tissue irritability, (4) artificial versus outdoor light, and (5) the angle at which the photograph was made. As technology advances, there will undoubtedly be other applications for computer graphics. The authors have successfully estimated outcomes for prosthodontic, orthodontic, and orthognathic surgical treatment. If properly used, color computer estimations can be successfully integrated in a dental office as a communication tool for the dentist, patient, and laboratory technician.

Cuspid↗
PubMed1997

Rietveld analysis and Fourier maps of hydroxyapatite.

Rietveld analysis was applied to the X-ray powder diffraction data of well-crystallized hydroxyapatites synthesized at 80 degrees C and pH 7.4. The least-squares refinement program adopted for Rietveld analysis showed good pattern fitting with the calculated profile. The a- and c-axis dimensions, a-0.943046 + 0.000126 nm and c-0.687485 +/- 0.000104 nm, were obtained and compared with the data estimated from a single peak. The lattice dimensions obtained by Rietveld analysis were much closer to the values of a single crystal, a = 0.9432 nm and c-0.6881nm. Fourier analysis was also performed. The maps of electron densities expressed the existing possibility of each atom composing hydroxyapatite in the crystal structure. In particular, columnar calcium and screw-axis calcium were clearly revealed. These data agreed well with the computer graphics model of hydroxyapatite reported previously.

Computer Simulation↗