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At least 1,045 records · Page 58Linked to original sources
PubMed1989

A computer-assisted learning tool designed to improve clinical problem-solving skills.

A computer-based teaching and learning program was developed to supplement the case load of students on a one-month emergency medicine clinical rotation and interactively measure and support improvements in their acute chest pain differential diagnostic skills. Students using the program demonstrated a significantly higher level of diagnostic accuracy than a control group (one-tailed t test; N = 88; P less than .018). The success of the program was attributed in part to its unique application of advanced interactive software. Specifically, students use the software (an expert system shell) to develop a computer-based acute chest pain differential diagnostic protocol. Students can subsequently challenge their protocol with a number and variety of training cases in the program's data bank. The software interactively apprises students of the performance of their protocol in terms of its diagnostic accuracy against the cases. Students make protocol modifications to improve its diagnostic accuracy against the training cases. Interactive reassessments of the protocol's performance against the cases follow each modification. This repetitive cycle of protocol modifications rapidly followed by interactive performance reassessments against training cases appears to result in efficient and effective differential diagnostic skills improvements. A new generation of computer-based teaching and learning tools may have a significant impact on undergraduate clinical education.

Angina Pectoris↗
PubMed2005

Use of computational fluid dynamics simulations for design of a pretreatment screw conveyor reactor.

Computational fluid dynamics simulations were employed to compare performance of various designs of a pretreatment screw conveyor reactor. The reactor consisted of a vertical screw used to create cross flow between the upward conveying solids and the downward flow of acid. Simulations were performed with the original screw design and a modified design in which the upper flights of the screw were removed. Results of the simulations show visually that the modified design provided favorable plug flow behavior within the reactor. Pressure drop across the length of the reactor without the upper screws in place was predicted by the simulations to be 5 vs 40 kPa for the original design.

Acids↗
PubMed1998

Stereolithography: application to neurosurgery

Computer-aided design (CAD) and computer-aided manufacturing (CAM) by stereolithography are already being widely used in industry for the design and manufacture of new parts and have already shown accuracy in reproducing the desired model. The only shortcoming of this technique is that it can only make one model at a time, a "prototype." It cannot be used for mass production. It is precisely this property, namely making a prototype, that makes it so attractive in reconstructive surgery and implantation of prostheses, where each "part" has to be adapted to the unique anatomy of the patient. It was not until the early nineties that reports of the application of stereolithography to reconstructive surgery appeared in the literature, and even now they are scarce. However, it is a very promising technique, and we think that it is important for physicians to familiarize themselves with this concept.

Journal Article↗
PubMed1995

The application of stereolithography to the fabrication of accurate molecular models.

The process of stereolithography, which automatically fabricates plastic models from designs created in certain computer-aided design programs, has been applied to the production of accurate plastic molecular models. Atomic coordinates obtained from quantum mechanical calculations and from neutron diffraction data were used to locate spheres in the I-DEAS CAD program with radii proportional to the appropriate van der Waals radii. The sterolithography apparatus was used to build the models using a photosensitive liquid resin, resulting in hard plastic models that accurately represent the computed or experimental input structures. Three examples are given to illustrate how the models can be used to interpret experimental structure-activity data for systems of biological importance or host-guest chemistry: (1) Interpretation of kinetic data for the formation of a stable blocking complex between amiloride analogs and the epithelial sodium channel, (2) interpretation of binding and neural activity data for the interaction of certain amino acids and their analogs at the L-alanine taste receptor of the channel catfish, and (3) interpretation of shape selectivity and rate acceleration in cyclodextrin catalysis using models of the neutron diffraction structure of beta-cyclodextrin and of the transition state for the cleavage of phenyl acetate by the secondary hydroxyl oxygen of beta-cyclodextrin.

Acrylates↗
PubMed1987

A computer program for the design of optimal synthetic oligonucleotide probes for protein coding genes.

A computer program has been written in FORTRAN 77 to locate on a protein sequence a region with optimum length and limited degeneracy in order to design artificial oligonucleotide probes for use in molecular cloning. In addition the program checks for regions of homology between this probe and any other base sequence found in nucleotide sequence data banks. There are options in the program to eliminate rare codons or to make preferential choices of bases in order to minimize the degeneracy of probes.

Algorithms↗
PubMed2002

Computational fluid dynamics insights in the design of mechanical heart valves.

Computational fluid dynamics (CFD) analysis can provide detailed, three-dimensional predictions of blood flow through mechanical heart valves, which can help to optimize valve hemodynamics and reduce the potential for blood clotting. A number of CFD studies, considering both forward and retrograde flow through valves, have been published. In this paper, a geometrically accurate CFD model capable of predicting the three-dimensional, time-dependent flow through an open ATS bileaflet valve is presented. A detailed picture of the blood flow is obtained, including small-scale flow features in the pivot regions. Results from the model can also be used to investigate the opening position of the ATS valve leaflets. Future work will be aimed toward improved models that provide valuable design information while minimizing the development time and computational resources required. Such practical CFD models clearly have the potential to reduce the costs, time scales, and risks associated with development of new heart valve designs.

Blood Flow Velocity↗
PubMed2005

Simultaneous population optimal design for pharmacokinetic-pharmacodynamic experiments.

Multiple outputs or measurement types are commonly gathered in biological experiments. Often, these experiments are expensive (such as clinical drug trials) or require careful design to achieve the desired information content. Optimal experimental design protocols could help alleviate the cost and increase the accuracy of these experiments. In general, optimal design techniques ignore between-individual variability, but even work that incorporates it (population optimal design) has treated simultaneous multiple output experiments separately by computing the optimal design sequentially, first finding the optimal design for one output (eg, a pharmacokinetic [PK] measurement) and then determining the design for the second output (eg, a pharmacodynamic [PD] measurement). Theoretically, this procedure can lead to biased and imprecise results when the second model parameters are also included in the first model (as in PK-PD models). We present methods and tools for simultaneous population D-optimal experimental designs, which simultaneously compute the design of multiple output experiments, allowing for correlation between model parameters. We then apply these methods to simulated PK-PD experiments. We compare the new simultaneous designs to sequential designs that first compute the PK design, fix the PK parameters, and then compute the PD design in an experiment. We find that both population designs yield similar results in designs for low sample number experiments, with simultaneous designs being possibly superior in situations in which the number of samples is unevenly distributed between outputs. Simultaneous population D-optimality is a potentially useful tool in the emerging field of experimental design.

Computer Simulation↗
PubMed2001

[Comparative analysis of results of mathematical simulation of stressed deformed status of pin dentures of different design].

A computer study of 99 types of mathematical models of teeth armed with stump pin insertions widely used in dentistry (group 1--anchor pins and group 2--cast pin insertions suggested by the authors). Tooth models differed by shape, size, and properties of the design material. The shape and parameters of stump pin insertion were proven to be more significant than the properties of design material. The choice of pin design is determined by the clinical situation, topography and anatomy of tooth crown destruction, and maxillodental disease.

Computer Simulation↗
PubMed2005

A novel neural network for the synthesis of antennas and microwave devices.

A novel artificial neural network (SYNTHESIS-ANN) is presented, which has been designed for computationally intensive problems and applied to the optimization of antennas and microwave devices. The antenna example presented is optimized with respect to voltage standing-wave ratio, bandwidth, and frequency of operation. A simple microstrip transmission line problem is used to further describe the ANN effectiveness, in which microstrip line width is optimized with respect to line impedance. The ANNs exploit a unique number representation of input and output data in conjunction with a more standard neural network architecture. An ANN consisting of a heteroassociative memory provided a very efficient method of computing necessary geometrical values for the antenna when used in conjunction with a new randomization process. The number representation used provides significant insight into this new method of fault-tolerant computing. Further work is needed to evaluate the potential of this new paradigm.

Algorithms↗
PubMed1993

An efficient method for computer-aided dosage form design.

It is desirable to have slow-release dosage form to be taken once daily, or at most twice daily, as compared to three or four times in a single day. However, the existing computer-aided dosage form design method requires a large amount of computer time when applied to nonlinear disposition drugs. This large commitment of computer time makes it inconvenient to study the feasibility for prolonged-release products containing such drugs. Instead of evaluating all possible combinations of the amount of dose and release rates that produce acceptable steady-state plasma concentrations, only the contour of the dose-release rate domain needs to be determined. An image boundary tracking method has been used to determine such contours. When combined with several modifications of the numerical solution process, the acceptable dose and release rate constants can be determined efficiently. When this modified boundary tracking method was applied to phenytoin, which exhibits nonlinear disposition, the required computer time was reduced to about 5% of the previous method, making the dosage form feasibility assessment practical.

Computer Simulation↗
PubMedDate not supplied

A survey of the information gained from planning treatment with a computer.

We designed a questionnaire to be filled out by the physicist at the time of planning treatment with the aid of a computer in order to assess what was learned during the course of the planning session. We analyzed the results to gauge the impact of the 70 treatment planning sessions conducted during the one month period in our department in which questionnaires were completed (about 72% of all external beam plans made in that period). In 65 instances (93%) an initial judgment as to how treatment would be delivered had already been made and in 56 of these cases the patient's treatment had already been simulated by the time the computer calculation was made. Changes in the intended plan were made in eight of the 65 cases (12%). In 38% of the cases, more than one plan was developed and, when this was the case, on average records of 2.6 plans were made. Those performing the plans were asked to judge their value to the overall treatment of the patient, and the results were as follows: essential-19 cases (27%); very helpful-22 cases (31%); and somewhat helpful-29 cases (41%).

Abdominal Neoplasms↗
PubMed2000

Computer simulation and geometric design of endarterectomized carotid artery bifurcations.

The main goal of this computational study is to establish surgical guidelines for optimal geometries of carotid endarterectomy reconstructions that may measurably reduce postoperative complications, that is, thrombosis, stroke, and/or restenosis. The underlying hypotheses are that nonuniform hemodynamics, or "disturbed flows," are linked to arterial diseases and consequently that minimization of "disturbed flow" indicators leads to geometric bifurcation designs that lower postoperative complication rates. Considering transient 3-D laminar blood flow in partially occluded, in-plane, rigid-wall carotid artery bifurcations, the results presented include time-averaged indicators of "disturbed flow", such as the wall shear stress, spatial wall shear stress gradient, and wall shear stress angle deviation. In addition, trajectories and deposition patterns of critical blood particles (i.e., monocytes) are shown and evaluated. Within given physiological constraints, the vessel geometry was then changed in order to reduce the magnitudes of key indicators associated with thrombosis (i.e., blood clot formation) or restenosis (e.g., renewed atherosclerosis and/or hyperplasia). The quantitative results and knowledge base generated will be crucial for future clinical trials.

Blood Flow Velocity↗
PubMed1996

Determination of connectivity density in human iliac crest bone biopsies assessed by a computerized method.

The aim of the present study was to design a computer program (based on the ConnEulor principle) for direct measurement of 3-D connectivity density in iliac crest bone sections, as used for conventional histomorphometry. We used the physical disector principle and developed an algorithm for nonlinear alignment of the disector pairs. 3-D connectivity was evaluated in transiliac specimens from 30 nonselected autopsy cases of 14 men (age range 20-84 years) and 16 women (age range 20-96 years). In order to visualize the findings from the disector pairs, 3-D reconstruction was performed for two of the iliac crest biopsies. The designed computer program aligns the two sections forming a disector pair and automatically depicts the differences between the images, thereby making correct, direct connectivity density measurements available for conventional bone research.

Adult↗
PubMed1986

Design of an integral computer-based wheelchair controller/linear synchronous motor system.

The purpose of this paper is to illustrate the advantages of designing computer-based motor controllers together with innovative motors, such that maximum controller/motor system benefits are obtained. Specifically, this paper describes how a computer-based controller/drive system for powered wheelchairs has been designed and is being built and tested. This type of integral controller/drive system has been possible to build into a wheelchair only with the advent of the microprocessor-based feedback motor controller. The type of motor chosen for this project was a linear synchronous motor (LSM), which is highly efficient (90%+) and could easily be made an integral part of a wheelchair wheel, providing a "no-moving-parts" drive system. However, an LSM cannot be variable-speed-controlled without knowledge of, and controlled adjustment to, the absolute rotor versus stator position at each point in time. Microprocessor-based feedback motor controllers make precise, efficient control of LSMs possible at a reasonable cost. In addition, this combination of controller and motor provides a very flexible wheelchair control/drive system that may be easily programmed to suit the needs and necessities of the wide variety of over 200,000 persons now using powered wheelchairs.

Algorithms↗
PubMed1981

Breast cancer detection utilizing biostereometric analysis.

Twelve female patients participated in a study designed to employ computer-assisted biostereometric analysis for the detection of breast masses. All breast masses were previously documented by physical examination and followed by xeromammography, stereophotography, and histopathologic confirmation of tumor type. "Contour mammograms" were produced from the biostereometric photographs. These data were analyzed first for tumor detection and location by visual inspection. A second analysis employed a computed algorithm designed to locate and measure surface aberrations that suggest the possibility of underlying breast tumor. Visual analysis yielded the exact location of breast tumors in eight of the ten malignancies; computer analysis exactly located nine of the ten malignancies. In the computer analysis, one malignancy not exactly located by quadrant was, nevertheless, located in the correct breast. The results of the study suggest that the biostereometric process may have future use in screening or prescreening procedures for breast cancer detection. It is noninvasive, applicable to large numbers of women and with suitable refinements, and capable of being fully automated.

Aged↗
PubMed1993

A computer program for the design of PCR primers for diagnosis of highly variable genomes.

PCRDiag (Diagnosis by PCR) is a computer program which allows the localization of pairs of oligonucleotides with optimal thermodynamic requirements for use in a PCR assay. The program is designed for the selection of pairs of primers complementary to sequences present in a group, whose identification is intended, but are absent in other non-specific sequences. The program constitutes a powerful tool, specially in systems which display a high degree of sequence heterogeneity, as is the case of RNA viruses. The program runs on IBM-PC and compatible computers and has no special software requirements. It does not need the previous alignment of the sequences analyzed.

Algorithms↗
PubMed1994

Computer aided microbial safety design of food processes.

To reduce the time required for product development, to avoid expensive experimental tests, and to quantify safety risks for fresh products and the consequence of processing there is a growing interest in computer aided food process design. This paper discusses the application of hybrid object-oriented and rule-based expert system technology to represent the data and knowledge of microbial experts and food engineers. Finite element models for heat transfer calculation routines, microbial growth and inactivation models and texture kinetics are combined with food composition data, thermophysical properties, process steps and expert knowledge on type and quantity of microbial contamination. A prototype system has been developed to evaluate changes in food composition, process steps and process parameters on microbiological safety and textual quality of foods.

Computer-Aided Design↗
PubMed2005

Design considerations for computer-based surgical simulators.

Computers will allow the creation of novel training environments in ways that can only be imagined at the present time. The design of computer-based simulators for training of surgical procedures is a highly complex and ever-more sophisticated process. A thorough understanding of human learning principles as well as the capabilities and limitations of simulation training is required. Only development teams with expertise in medicine and surgery, computer science, hardware engineering, and simulation training will be able to create the useful surgical simulators of tomorrow.

Journal Article↗