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At least 397 records · Page 22Linked to original sources
PubMed1987

Computer aided design of pellets for fixed-bed reactors performing Michaelis-Menten reactions.

The problem of designing the pellet characteristics for existing fixed-bed reactors has been studied. The reactor is assumed to be a unidimensional, plug-flow, heterogeneous type. Three particle shapes, two intraparticle mass transfer mechanisms, two kinds of film resistance to mass transfer and two poisoning patterns have been considered. An economic balance to both product market price and pellet market cost was taken into account. An interactive program (HIMER) containing all these contributions was thus developed, enabling the investigator to follow the reactor performance along the flow coordinate.

Algorithms↗
PubMed1991

Computer-aided design of two-dimensional electric-type hyperthermia applicators using the finite-difference time-domain method.

A hyperthermia applicator design tool consisting of a finite-difference time-domain (FDTD) technique in combination with a graphical display of electric fields and normalized linear temperature rise is described. This technique calculates, rather than assumes, antenna current distributions; it includes mutual interactions between the body and the applicator, and it calculates driving-point impedance and power delivered to the applicator. Results show that the fundamental limitation of 2-D electric-type applicators is overheating of the fat by normal components of the electric field, which exist because of near fields and capacitive coupling with the muscle. Two factors which contribute to the capacitance are the muscle conductivity and the small antenna size in air. Two examples of applicators designed to avoid fat overheating are described: a 27-MHz segmented dipole for heating large tumors to 7 cm depth, and a 100-MHz dipole for small tumors to 5 cm depth. The first uses a water bolus, and the second uses a water bolus with low-permittivity strips to reduce normal fields at the antenna ends. The results of this study describe fundamental limitations of electric field applicators, and illustrate the use of a powerful applicator design tool that allows rapid evaluation of a wide range of ideas for applicators which would require months and years to test experimentally.

Algorithms↗
PubMedDate not supplied

Computer-assisted design of surface coils used in magnetic resonance imaging. I. The calculation of the magnetic field.

For a number of reasons, it is desirable to fabricate coils which, for a known current, shall produce predetermined values of the magnetic field intensity at a number of points within a nuclear magnetic resonance imager. The calculation of the magnetic field intensity at a set of points involves the integration of the Biot-Savart equation for all components of the segments of conductor which make up the coil. This process in itself is a rather formidable task. When this process is parameterized in terms of coil diameter, coil spacing, etc. the problem is to determine the values of these parameters to match values of magnetic field intensities which are desired. The problem thereby increases in complexity to the point where, by ordinary methods, the problem becomes intractable. This note describes an algorithm and offers a computer subroutine to calculate magnetic fields for coils of arbitrary shape and complexity for fixed currents.

Electromagnetic Fields↗
PubMedDate not supplied

Computer-assisted design of surface coils used in magnetic resonance imaging. II. Rotational discrimination nonlinear regression analysis and the design of surface coils.

For a number of reasons, it is desirable to fabricate coils which, for a known current, shall produce predetermined values of the magnetic field intensity at a number of points within a nuclear magnetic resonance imager. The calculation of the magnetic field intensity at a set of points involves the integration of the Biot-Savart equation for all components of the segments of conductor which make up the coil. This process in itself is a rather formidable task. When this process is parameterized in terms of coil diameter, coil spacing, etc. the problem is to determine the values of these parameters to match values of magnetic field intensities which are desired. The problem thereby increases in complexity to the point where, by ordinary methods, the problem becomes intractable. A generalized solution technique has been developed on a digital computer to implement the rotational discrimination nonlinear regression techniques of Faris, Law and Letcher to find the best solution to this problem. The problem is posed by integrating the Biot-Savart equation. This produces algebraic expressions for incorporation into the optimization program which is executed on a computer in a conversational mode. This technique was employed to specify the dimensions of a rectangular surface coil for the investigation of the whole human spine.

Equipment Design↗
PubMedDate not supplied

Computer-assisted design of surface coils used in magnetic resonance imaging. III. The design and construction of two long twin axial antennae for imaging of the whole human spine.

Two modified folded dipole MRI surface coils were designed, constructed and tested. These antenna which are long twin axial lines use the effective distributive capacitance resulting from the distance between two longitudinal elements to provide tuning. The principal advantage of this type of antenna is the ability to image longer objects such as vertebrae, spinal cord, and longer portions of the extremities. This type of antenna shows less localized high intensity in the image due to a more evenly distributed current pickup from the sample. The coils were designed by calculating theoretical magnetic field distribution for the twin axial coils. These were obtained by integrating the Biot-Savart equation. This gave excellent agreement with an MR image of a di-electrically uniform phantom. As antennae of this sort are nonlinear in response, giving rise to an image intensity nonuniformity, computer software for the MR image was developed to correct the image intensity profile over the experimental volume. The software significantly improved the image quality by reducing the saturated intensity of the region near the antenna, thereby revealing detailed structure of the tissue being imaged.

Equipment Design↗
PubMed1987

Prediction of exposure degree diagram and sites of limited proteolysis in globular proteins as an approach to computer-aided design of protein bioregulators with prolonged action.

In order to prolong the lifetime of protein bioregulators in blood it is possible to engineer analogs with protected sites of limited proteolysis. To determine the sites, primarily accessible to trypsin-like proteases, a computer procedure has been developed, including a prediction algorithm, to produce the residue diagram of a globular protein and a discriminant algorithm to determine the sites most liable to proteolysis. The accuracy of prediction of amino acid residue exposure is characterised by correlation coefficients between experimental and theoretical exposure values, the coefficients being about 0.7 as calculated for 10 globular proteins. The classification of Arg and Lys residues into two groups, susceptible or insusceptible to protease, has an error percentage of about 25.

Arginine↗
PubMedDate not supplied

NCTR computer systems designed for toxicologic experimentation. I. Overview.

Established in 1971 by the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA), the National Center for Toxicological Research is committed to the study of long-term, low-dose effects of potentially toxic substances, including carcinogens. The Scientific Information Systems Division (SISD) facility provides logistic support for complex experiments involving large numbers of test animals. Animal population at the Center, including the breeding colony and animals on experiment, can be as high as 80,000. Each animal must be accounted for, fed and watered under strict control, and continually observed. From birth to final examination, an individual animal might have as many as 3,000 individual elements of information associated with it. This paper introduces a series of reports dealing with an integrated and comprehensive system of experiment planning and implementation (including information gathering, classification, analyses and reporting), employing state-of-the-art data processing techniques. This extensive use of computer technology has permitted the collection, proper classification, and rapid retrieval of virtually error-free data, resulting in cost-sensitive experiment planning.

Computers↗
PubMedDate not supplied

NCTR computer systems designed for toxicological experimentation. II. Experiment start-up system.

The Experiment Start-Up System (ESS) developed and implemented at the National Center for Toxicological Research constructs models from information contained in experimental protocols. These models may then be used to project resource requirements and related schedules. Each experimental model provides information from which management can determine the raw resources such as quantity of food, water, bedding, cages, animals (sex, strain, species), chemical, facilities, and manpower needed for conducting the experiment. Based upon this information, management can determine if the required resources are available and determine the most feasible "start" date for the new experiment. In addition, the information provided by the experimental model assures the Principal Investigator that the protocol requirements are thoroughly understood by participating technical support groups and that quality control elements of the ESS and other integrated systems will provide a means for accurately monitoring the experiment.

Computers↗
PubMed1994

Automated fabrication of mobility aids: review of the AFMA process and VA/Seattle ShapeMaker software design.

Computer-aided design and manufacture of prosthetic and orthotic devices has recently moved out of the laboratory into clinical use. The Department of Veterans Affairs Rehabilitation Research and Development Service has directed coordinated evaluation and development projects of this emerging technology under the name: Automated Fabrication of Mobility Aids or AFMA. One of the major results of the effort was the creation of mobility aid design software (ShapeMaker) concurrent with AFMA clinical testing of preexisting systems and development efforts. In order to provide a foundation for future discussions regarding AFMA, this paper provides a descriptive review of the AFMA processes and a review of the conceptual basis for the ShapeMaker AFMA software development.

Artificial Limbs↗
PubMed1989

VLSI processors for signal detection in SETI.

The objective of the Search for Extraterrestrial Intelligence (SETI) is to locate an artificially created signal coming from a distant star. This is done in two steps: (1) spectral analysis of an incoming radio frequency band, and (2) pattern detection for narrow-band signals. Both steps are computationally expensive and require the development of specially designed computer architectures. To reduce the size and cost of the SETI signal detection machine, two custom VLSI chips are under development. The first chip, the SETI DSP Engine, is used in the spectrum analyzer and is specially designed to compute Discrete Fourier Transforms (DFTs). It is a high-speed arithmetic processor that has two adders, one multiplier-accumulator, and three four-port memories. The second chip is a new type of Content-Addressable Memory. It is the heart of an associative processor that is used for pattern detection. Both chips incorporate many innovative circuits and architectural features.

Astronomy↗
PubMed1993

A burn patient resuscitation therapy designed by computer simulation (BET). Part 1: Simulation studies.

This study presents an analysis of the fluid, electrolyte and colloid needs of burn patients during the shock phase. A digital simulation technique was used which had previously been validated and published in burned patients (Roa et al., 1988). After analysing the repercussions of both burns and various resuscitation procedures, a fluid therapy method (BET) has been designed using a burn patient simulator, which has been characterized by its effectiveness and minimal side-effects. The characteristics of the BET method are a low volume of infusion resuscitation solution (220 ml/h/m2 burned body surface area (BBSA)) and a rapid and large volume of colloidal substances (with colloid concentrations of 10, 7.5 and 5 g/100 ml during the first three 8 h periods of the first postburn day and 2.5 g/100 ml until the 40th h postburn).

Burns↗
PubMed2006

The effect of sacral fracture malreduction on the safe placement of iliosacral screws.

OBJECTIVES: To determine the effects of cranial displacement on the safe placement of iliosacral screws for zone II sacral fractures. DESIGN: Computer imaging and dimensional analysis of a human cadaveric sacral fracture model. SETTING: Cadaveric dissection, Orthopaedic Research Laboratories, Newark, New Jersey. MAIN OUTCOME MEASUREMENTS: Six cadaveric pelves with simulated zone II sacral fractures were imaged with computed tomography at controlled cranial displacements of 5, 10, 15, and 20 mm. The area of contact at the fracture site and volume of bone available for iliosacral screw placement was graphically measured using both two- and three-dimensional computer modeling. Areas of contact were also represented in terms of the maximal number of 7.0 - mm screws that could be simultaneously implanted. RESULTS: Cross-sectional contact area was decreased by 30%, 56%, 81%, and 90% at 5, 10, 15 and 20 mm of displacement, respectively. Volume of bone was decreased by 21%, 25%, 26%, and 34% for 5, 10, 15 and 20 mm of displacement, respectively. In 50% of the specimens at 15 mm and 66% of the specimens with 20 mm displacement, two iliosacral screws could not be contained simultaneously within bone. In 17% of the specimens displaced 15 mm and 50% of the specimens displaced 20 mm, the cross-sectional area was insufficient to contain a single iliosacral screw. CONCLUSIONS: Although previous authors have accepted up to 15 mm of cranial displacement, the data demonstrate substantial compromise of available screw space with displacements greater than 1 cm. Fracture reduction is mandatory, as screw placement with residual displacement of 10 mm or more can endanger adjacent neural and vascular structures.

Aged↗
PubMedDate not supplied

NCTR computer systems designed for toxicologic experimentation. III. Breeding information system.

The Breeding Information System (BIS) facilitates management control of the breeding colony operation at the National Center for Toxicological Research (NCTR). Although this automated data handling system was initially intended to support Animal Husbandry the system's basic design, flexibility or reporting, data manipulation capabilities, and integration with other NCTR data collection systems provides BIS with capabilities that have application to other groups including the Plans and Programs and most scientific areas. This description of the System is in terms of its potential value to these diverse user groups.

Animal Husbandry↗
PubMed1998

Designing computer-based frameworks that facilitate doctor--patient collaboration.

A current trend in medicine involves establishing collaborative problem solving between patients and physicians in order to involve patients more in their own care. Neither diagnosis nor therapy can be completely successful unless the patient and the doctor understand each other and collaborate with each other in an effort to gauge the other's requests, needs and concerns. This is made even more difficult by the fact that there is often a big difference between the doctors and patients in terms of expectations, vocabulary used, and other factors. For diagnosis of many disorders, a detailed description of the problem and of the patient's history are required. For therapy, patients must understand how and when to take prescribed drugs, what changes to make in diet, exercise, or lifestyle and why they are important. This paper describes a model of asynchronous collaboration between people with very different knowledge of medicine in which a computer framework attempts to mediate between patients and physicians and reduce some of the differences in communication. It allows patients to pace themselves in familiarizing themselves with the relevant domain terms, some of the medical factors underlying the conditions under question, and the justifications and implications of the prescribed treatment plan. It also allows physicians to request more information of patients and gives patients contextual information to help them understand the underlying reasons for the questions. This framework has been partially implemented in the domain of migraines. As described in the paper, not only is the system designed to cooperate with the patient, but using the system also results in better mutual understanding between the doctor and the patient, thus leading to better collaboration between them.

Artificial Intelligence↗
PubMed2003

Improving the human computer interface design for a physician order entry system.

The computerized physician order entry (CPOE) system has become a primary focus of time and monetary investment in the healthcare arena. This focus is partly due to the need to reduce medical errors that occur due to illegibility, drug interactions, and misplaced decimals. A CPOE system can potentially prevent many of these errors, resulting in a significantly safer healthcare system. However, only one-third of the hospitals in the United States have installed CPOE systems, and only 1 percent of these require the physicians to use them.1 The success and failure of such a system is dependent on the acceptance by the users, in this case, the physicians. Unfortunately, many of the CPOE systems are not designed to address usability issues. They are hard to use, hard to learn, and they often generate user frustrations and abandonment. In this project, the user interface of one such software program was analyzed. As a result of this analysis, a prototype was developed as a component of the system to offer alternative solutions to the identified usability problems.

Hospital Information Systems↗
PubMed1980

A package of computer programs designed to simulate pharmacokinetic monitoring of drug therapy.

Three programs are presented which have been developed to simulate conditions encountered in the pharmacokinetic adjustment of dosage regimens. The programs include a drug with one-compartment kinetics, whose elimination is dependent on renal function (gentamicin), a drug with two-compartment kinetics (theophylline), and a drug whose elimination follows non-linear Michaelis-Menten kinetics (phenytoin). The programs may be used as an aid to instruction in clinical pharmacokinetics and to develop and test new methods of pharmacokinetic adjustment of dosage regimens.

Computers↗