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A program for serial section reconstruction using computer graphics on a microcomputer is described, which uses freely available non-specific hardware and software. Individual section data are input from a digitizer pad, and their reconstructed composite image can be displayed as if viewed from any direction.
The use of computer-generated slides in weekly didactic conferences and at regional and national meetings is commonplace. Though adding a professional look, the expense of computer-generated slides can be prohibitive. We herein present a simple technique for generating color slides that captures the professional look of computer-generated slides at a fraction of the cost.
Three-dimensional computer graphics are used to depict multidimensional outcome measures in a clinical drug trial. This graphics approach was used in a study of 116 patients with active rheumatoid arthritis, in a randomized, double-blind 21-week comparison of placebo, oral gold, and injectable gold. Three health status components, physical disability, psychological status, and pain, were generated using the Arthritis Impact Measurement Scales (AIMS). Results were presented in a three-axis perspective, one axis for each component, plotting individual patient vectors for magnitude and direction on a 10 X 10 X 10 coordinate matrix. Vectors for each patient are plotted from time 1 (start) to time 2 (finish) over the 21-week trial period. Vector symbols were added for clarity and subgroup delineation. Vector displays show trends in treatment response that clarify and strongly reinforce the statistical results. It is concluded that three-dimensional vector graphics are a useful adjunct to the statistical analysis of clinical trial results. The graphics facilitate the visual interpretation of a complex data set, and clarify the analysis of the results for both the clinician and researcher.
The presentation of areal data in epidemiology is illustrated by such mapping techniques as dots (spots), shading (choropleth, thematic) and isolines (isopleths). Examples are also given of computer-assisted cartography (computer graphics) which employs hardware and software components of digital computers, together with the use of geographical and demographic base maps.
An inexpensive system was developed for automated on-line analysis of ST segment heights, Q, R, and S heights and areas under these peaks, using an LSI-11 microcomputer. System accuracy was evaluated using a computer graphics technique which enabled magnification and labelling of the computed peaks on 60 maps from 17 patients. To compare the computer with hand analysis, the sigma ST (.06 seconds from S nadir) for 20 maps was calculated by three blinded observers. Correct computer evaluation occurred in all but five of 2058 leads. The mean observer sigma ST was 3.2 millivolts (range 0.77-7.5 mv). Mean inter-observer SD was +/-0.21 mv. The mean computer sigma ST was 3.5 mv (range 0.82-9.3 mv). The spread between computer and observer was +/-0.45 mv. Discrepancies between computer and observer were due to cumulative imprecision in observer measurements. This system has proven to be a practical and economic solution to handling the large volume of data accumulated with serial precordial mapping. It is considerably more precise than conventional hand analysis. Additionally, the system's versatility makes it ideally suited to many clinical and research functions.
The morphologies of food polysaccharides described in this chapter illustrate the power of x-ray fiber diffraction in conjunction with computer modeling and sophisticated refinement techniques. On the other hand, the lack of information on structures such as xanthan reflects the inadequacy of the experimental techniques used to date. But the demands from academic and industrial sectors to investigate the molecular interactions in multicomponent systems, including protein-protein, protein-polysaccharide, polysaccharide-polysaccharide, and other complexes, are high and growing, because they have important food applications. These complexes are structurally more difficult than those solved in the past 40 years and it is improbable that any chosen system will be amenable for crystallographic investigation, crystals or fibers. Modern research facilities that include two-dimensional area detectors, millisecond exposures with synchrotron x-ray radiation, interactive computer graphics, sophisticated molecular dynamics calculations, unbelievably fast and inexpensive computers, and our own intellectual abilities are indispensable tools for the future of structural science in general and food polysaccharides in particular.
A method for making three-dimensional computer graphics displays of in vivo blood vessels is described. Input data are taken from biplane X-ray angiograms using an image-processing system. A display list is built up which is then sent to a high-function graphics system. Real-time interaction is possible using a vector-refresh display where the blood vessel segments are shown as cylinders of the appropriate diameter. Realistic raster representations may be used to give the user insight into the overall topology of the network of vessels. The Winchester Graphics System is described together with explanations of the techniques employed.
A computerized medical record changes the way a clinician practices medicine by presenting data about patients in multiple organized formats. A computerized record can be used to make it more difficult to overlook important findings. The computer can improve communication by informing both the patient and referring physicians of new data as they become available. Computer graphics or algorithms can be used to emphasize subtle trends. A computer data base can be used to aggregate data about selected patients to provide information about the natural history of disease and effect of treatment.
Five experiments were conducted to test the hypothesis that observers apprehend specific constancies under change in perspective. The constancies were projective properties of ellipses pictured to slant and tilt in depth. Observers were asked to reproduce the static upright view of a moving pair of ellipses, using a computer graphics display and interface. Projective invariants for pairs of conics were computed on the observers' productions. A few experimental conditions revealed near-perfect performance. When pairs of coplanar ellipses were viewed under dynamic transformation in perspective, then invariants calculated on the observers' productions were a match--in value on average--to the invariants of the transforming ellipse pairs. It is proposed that measures of projective properties afford a family of techniques that can be applied to gauge acuity for complex shapes in the study of visual form perception.
The limited number of RNA structures determined by X-ray crystallography and NMR spectroscopy compels the use of experimental and theoretical methods that are less precise to obtain information on RNA conformation. RNA flexibility, a consequence of rotational freedom about seven intra- and internucleotide bonds, is unfortunately of such magnitude that these alternate techniques fall short of providing sufficient information to build robust tertiary structures. Various RNA modeling methods, described herein, permit the organization of this structural data to the form of three-dimensional structures. Interactive computer graphics techniques, for example, have generated several useful models. Also, conventional computer algorithms involving the minimization of empirical energy functions, previously limited to small molecules, are giving way to methods able to handle much larger molecules. Modified distance geometry and molecular mechanics algorithms, using simplified "pseudoatom" representations, can generate structures consistent with input data. A constraint satisfaction algorithm combined with discrete representations of nucleotide conformations systematically explores poorly defined regions of a molecule yielding all-atom representations, but requires enough structural constraints to avoid a computational explosion.
An interactive graphics display system (IGDS) which presents perspective views of wire frame models is described. The display unit is a microprocessor driven TERAK 8510a system with a grid of 320 . 240 points. A brief discussion of the hardware is given. While the system is quite general - it can draw a perspective view of any type of wire frame model - emphasis here is on molecular models. The graphics software has been written in UCSD PASCAL. The program employs traditional computer graphics algorithms available in the literature, The data structure used by the program was designed to occupy minimal disk storage space. Data files can be constructed locally or can obtained through a communications link with with a central computer facility. Despite the inherent slowness (due to matrix operations being performed by the software calculations rather than hardware), the low cost of the system suggests general applicability. The program is easy to use, interactive, and produces good results from systems up to 200 points.
The design and use of a PDP 11/40 based automated on-line cardiac pacemaker assessment system is described. One program has been developed for testing pacemakers on the bench and another for implanted pacemaker tests. Either fixed rate or demand pacemakers can be tested. The on-line system is easy and fast to use and is also highly accurate. Parameters extracted are pulse width, rate and pulse energy. In addition, a graphical representation of the patient's ECG and the pacemaker pulse is obtained on a computer graphics terminal.
Many individuals with movement disorders are unable to make efficient use of graphical computer interfaces commonly employed in personal computers. In this study, performance limitations in target tracking with a computer mouse were studied for eight young subjects aged 19 to 29 (M = 23, SD = 3), four old subjects aged 70 to 73 (M = 72, SD = 1), and five motor-disabled subjects aged 37 to 74 (M = 65, SD = 16). Subjects tracked simple one- and two-dimensional motions at various frequencies. Performance was measured using an accuracy index derived from root-mean-square error, and a linearity index based on coherence estimation. A maximum bandwidth of 2 Hz for accuracy of mouse use was found, which often decreased due to advanced age or motor disability. Tracking linearity of all groups decreased as frequency increased. A significant degree of nonlinearity existed in all results (p < 0.05), with disabled subjects nearing complete nonlinearity in two-dimensional tracking. The data show that with advanced age and disability, mouse use becomes increasingly inaccurate and nonlinear. Assistive computer interfacing techniques, such as signal filtering, may improve mouse use.
We present a prospectus on the use of computer graphics for the three-dimensional reconstruction and visualization of brain lesions from computed tomographic head examinations, including an algorithm that utilizes surface contour information to reconstruct and display three-dimensional anatomical sites. We provide examples of the use of this algorithm. We offer an algorithm for estimation of the volume and surface area of anatomical sites. The advantages and disadvantages for the clinical use of these algorithms are discussed.
A lack of understanding of simple standards is responsible for poor quality graphics in slides, overhead projection transparencies, posters and publications. The ready availability of computer graphics application programs has led to a proliferation of well-executed, but poorly constructed illustrations. Guidelines are given for the design of scientific illustrations, with reference to correct labelling, line weights, font styles and sizes, the use of colour, and other factors affecting the clarity of presentation. The application of established standards for the preparation of medical graphics as described is strongly recommended.
In this paper we would like to show importance of using modern information technology in implementation and development of health information systems. Our main focus is on doctor's work. Doctors will use computer only if they will see clear advantages. Traditional data gathering and display are not sufficient, so modern software should provide speech interfacing and computer graphics in various applications and enable the use of electronic mail, hand held computers, electronic data interchange, etc. among other features. This paper tries to show the needs for applications of those features. They are already implemented as part of our hospital information systems.
Electron microscopy of human immunodeficiency virus (HIV) has provided evidence for a virion model which when sectioned, consists of a circular envelope surrounding an inner conical core. When sections are perpendicular to the core axis, the envelope is still circular, but the tapered core appears as a dot near the center of the envelope. An observation inconsistent with the present model is the frequent finding of an electron-lucent "polygonal window" associated with the virion envelope. Here, we provide evidence for a new model of HIV. This model, which accounts for the polygonal windows and the shape of the envelope, places the conical core inside a regular polyhedron that lies just under the envelope. We tested the validity of various polyhedrons with three-dimensional computer graphics which emulate thin section electron microscopy. With this technique, about 2000 computer-generated "thin sections" of HIV-models were compared with electron micrographs of HIV. A structure consistent with the computer-generated data reveals a detailed model for HIV with the following features; (a) the conical core is inside an envelope-associated capsid having icosadeltahedral symmetry. This envelope-associated capsid is 60-sided and contains 32 vertices, 20 of which have hexagonal symmetry and 12 of which have pentagonal symmetry, (b) the inner rodlike core abuts the inside of any 2 opposing hexagonal vertices, (c) the pentagonal vertices do not support the inner core. A comparison of these results with that of Gelderblom et al. (Gelderblom HR, Hausmann EHS, Ozel M, Pauli G, Koch MA: Fine structure of HIV and immunolocalization of structural proteins. Virology 156: 171, 1987), suggests that the p17 polypeptide is a component of the envelope-associated icosadeltahedral capsid. This computer emulation technique provides a thorough test of this model of HIV, but does not constitute proof. Additional testing methods such as bidirectional metal shadowing and freeze etching will be needed to confirm this new virion structure. Additionally, this computer technique may be useful for testing the proposed morphology for cell organelles.
Despite the increasing amount of patient data in the area of words and numbers that is being stored by computer, the graphic storage of ophthalmological findings has found only limited success. However, a sketch is much more instructive than a description in words. This paper shows that by using a suitable computer with a graphic oriented disc-operating system and a purchasable graphic and data base program, it is easily possible to generate sketches of retinal detachment on a computer screen. In the graphic program, all of the necessary symbols are already available when the program is started. The user just makes a copy of the symbols he needs to "draw" the actual fundus findings. We use the system of Meyer-Schwickerath. Afterwards, the drawing on the monitor is transferred into the data base program and stored.