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At least 19 recordsLinked to original sources
PubMedDate not supplied

Modelling and simulation of information systems on computer: methodological advantages.

Modelling and simulation of information systems by the means of miniatures on computer aim at two general objectives: (a) as an aid to design and realization of information systems; and (b) a tool to improve the dialogue between the designer and the users. An operational information system has two components bound by a dynamic relationship, an information system and a behavioural system. Thanks to the behaviour system, modelling and simulation allow the designer to integrate into the projects a large proportion of the system's implicit specification. The advantages of modelling to the information system relate to: (a) The conceptual phase: initial objectives are compared with the results of simulation and sometimes modified. (b) The external specifications: simulation is particularly useful for personalising man-machine relationships in each application. (c) The internal specifications: if the miniatures are built on the concept of process, the global design and the software are tested and also the simulation refines the configuration and directs the choice of hardware. (d) The implementation: stimulation reduces costs, time and allows testing. Progress in modelling techniques will undoubtedly lead to better information systems.

Computers↗
PubMed1983

Computer methodology for simulation and prediction of alloimmune responses: expected antibody specificities.

The methodology presented here was developed for simulating planned alloimmunization results, with regard to the type and number of expected antibody specificities. The computer program designed for this purpose was adapted to an immunogenetic model using Boolean algebra. It was written to help immunogeneticists avoid handling routine data preceding selection of donor-recipient pairs, specially concerning blood type alloimmunizations in animals: all of the donor-recipient combinations and the expected antibody specificities (their limit number being specified in each particular immunization program) are provided in the print-out.

Animals↗
PubMed1980

Computed tomography/guided stereotactic surgery: conception and development of a new stereotactic methodology.

Computed tomography (CT) has become the first modality to provide the patient's self-brain map for stereotactic neurosurgery. This paper describes our development of a nearly artifact-free stereotactic frame designed for CT imaging. The surgical procedure is performed within the CT scanner itself. The scanner's computer, via a new software program, spatially integrates the new stereotactic frame with the CT images of the patient and with the scanner gantry to provide rapid coordinate determinations, calculate potential probe trajectories, obtain target accuracy within 1 mm, and observe for any procedural complications. Our initial clinical experience with this system is described.

Brain Neoplasms↗
PubMed1993

[Stable xenon computed tomography. Methodology and clinical application].

According to the principle of the dynamic computed tomography, stable xenon computed tomography allows measurement of the increase in density caused by xenon in the brain tissue. During a period of about 4 min a patient inhales a mixture of xenon (33%) and oxygen. By means of a special software, this method can be used to calculate flowmaps and to determine the local cerebral blood flow in a 1 cm x 1 cm areal. Stable xenon computed tomography is used mainly for cerebral blood flow measurements in patients with cerebrovascular diseases and also allows calculation of cerebral reserve capacity following stimulation of blood flow by the carboanhydrase inhibitor acetazolamide (Diamox).

Acetazolamide↗
PubMed1980

[Computer aerography. Methodology and clinical use exemplified by labio-maxilla-palate clefts (author's transl)].

Computer aerography, which is based on the use of the double-aerometer by Sven Smith, is described as an objective method for clinic-scientific problems. Medical examination of labio-maxilla-palate-cleft patients shows how this procedure, which has a low degree of inconvenience and is also applicable to children, contributes essentially to the settling of clinic-scientific problems. Further scopes are still being tested.

Cleft Lip↗
PubMed1984

Computer based methodology for construction of orthodontic arch wire templates.

This paper presents the details and logic of two Fortran computer programs. The program, BRACKET, is designed to evaluate the constant relationship among teeth and orthodontic brackets to which an arch wire is adapted. The program, WIRE, is used to initially fit brackets to teeth using the constants derived in BRACKETS, based upon a series of orthogonal transformations. Subsequently, an orthodontic arch wire is fitted through the brackets, and the results are displayed using computer graphics. It is anticipated that the system would be useful in the orthodontic clinical setting as an aid in arch wire formation. The graphics produce a template which incorporates essential points to consider in arch wire formation, namely, perimeter length, lateral widths, symmetry, and appropriate arch form for the patient.

Computers↗
PubMedDate not supplied

Improvement in Fourier analysis of gated blood-pool studies using single photon emission computed tomography: methodology and clinical feasibility.

We have developed a new method for obtaining reconstructed left ventricular (LV) planar images acquired from multidirectional views using gated blood-pool single photon emission computed tomography (SPECT), and have applied Fourier analysis to these planar images. In this paper, we describe the methodology of our new technique and discuss its feasibility for the detection of LV wall motion abnormalities (WMA) in patients with coronary artery disease (CAD). Sagittal long-axis, horizontal long-axis and short-axis sections of the LV were generated from the reconstructed transaxial tomograms. Sections covering only the LV at the same phase of the cardiac cycle were added to reconstruct planar images. Fourier analysis was then performed to construct phase and amplitude images. In 42 patients with significant WMA, a comparative study concerning the detection of WMA was performed between conventional and SPECT methods. The SPECT method had greater sensitivity in all segments of the LV, with no significant loss in specificity. In particular, the sensitivity of the SPECT method was significantly greater than that of the conventional method for inferior and posterior WMA (91% vs 57%; and 76% vs 35%, respectively). The method described here shows greater clinical effectiveness for the detection of LV WMA in patients with CAD.

Adult↗
PubMed1986

Quantification of scalp hair--a computer-aided methodology.

A method for obtaining a quantitative assessment of hair density is described. First, a photographic image of the scalp is digitized onto a high-resolution computer graphics screen. Second, the frequency of each of 256 gray levels (one for each of 500 vertical X 500 horizontal = 250,000 locations on the screen) is obtained and the frequency histogram of gray levels is displayed. Third, a statistical procedure, gaussian mixture analysis, is used to resolve the frequency distribution into two normally distributed component distributions. The first component distribution describes the range of gray levels that are typically associated with hair. The second component distribution describes shades of gray that are typically associated with scalp. The statistical model provides a precise measure of the proportion of the head that exhibits gray levels in each of the two component distributions (hair or scalp). The proportion of the first component distribution is a scale-independent measure of hair density. The difference in this quantity before and after treatment provides an accurate quantitative determination of the change in hair density and hence of the efficacy of treatment.

Alopecia Areata↗
PubMed1982

Assessment of prostatic size with computed tomography. Methodologic aspects.

The prostatic gland can be easily demonstrated on CT scans and its volume has been estimated using the ellipsoid formula. In 32 patients with benign prostatic hyperplasia calculated volumes were compared with the weight of the adenomas resected at open surgery. A good correlation was found (r = 0.89) with an average residual error of 12 g. The method is considered valuable for preoperative assessment of the prostatic size and useful as a non-invasive method to evaluate changes in prostatic volume following different types of non-surgical treatment.

Aged↗
PubMed1992

[Portal computed tomography. Methodology and indications].

CT arterioportography (CTAP) requires intra-arterial contrast material via the superior mesenteric (splenic) artery. Malignant hepatic tumors are characterized by arterial vascularization and only minimal portal blood supply. Portal contrast therefore reveals small tumors with a high sensitivity of 68-87%. Sensitivity is higher in metastatic tumors than in hepatocellular carcinomas. CTAP is the method of choice for evaluation of the number, size and location of hepatic tumors prior to surgical intervention. If the findings are unclear, additional magnetic resonance imaging and sonography during the operation are useful.

Contrast Media↗
PubMed1989

Novel computer optimization methodology for pharmaceutical formulations investigated by using sustained-release granules of indomethacin.

A modified optimization technique, based on the response surface methodology, was developed for selecting pharmaceutical formulations. In general optimization methods, it is difficult to insure that the optimum formulation is strictly obtainable. Thus, the combined use of random number techniques and Andrews' plots with general optimization methods was investigated for seeking the optimum formulation. The method developed in this study was applied to the optimization of a sustained-release formulation based on the interpolymer complex of polyvinylpyrrolidone with carboxyvinyl polymer. Indomethacin was selected as a model drug for which sustained-release formulations are desirable. Experimental results obtained for the optimum formulation agreed well with the predictions, indicating the usefulness of this approach.

Chemistry, Pharmaceutical↗
PubMed1993

Determining heart-rate variability: comparing methodologies using computer simulations.

Heart rate variation due to respiration is a window onto autonomic nervous system function and many measures exist that quantify this variability. Computer-based simulations of 1-minute deep-breathing tests, along with common artifacts, were used to compare the most frequently used measures. We found distinct differences in the performance of the measures. Some measures (e.g., SDRR and MSSD) are strongly influenced by the underlying mean heart rate while others (e.g., Max-Min and SDHR) are not. All of the measures tested, except R, were influenced by both shifting mean heart rate and single-beat anomalies. R, on the other hand, is strongly influenced by test duration and breathing asynchronies. Sensitivity to phenomena unrelated to ANS function can reduce the diagnostic discrimination of these measures. We suggest simple improvements to the measures and discuss how some measures may be theoretically superior to others.

Computer Simulation↗
PubMedDate not supplied

Profiling of endogenous brain peptides and small proteins: methodology, computer-assisted analysis, and application to aging and lesion models.

Significant advances in the technology for the isolation of peptides and small proteins have permitted their identification as biologic markers and enhanced the study of the posttranslational life of proteins. The protocol described here examined large numbers of tissue-derived peptides and small proteins, extracted in low pH and boiled so that proteolysis was interrupted. These were then fractionated batchwise using size exclusion and ion-exchange chromatography. Profiles of species in the peptide pools were then generated on reverse-phase high-performance liquid chromatography (HPLC). The HPLC profiles were evaluated with chromatographic analysis software to identify and quantify peptide peaks and with data compilation programs to sort this information into spreadsheets for comparison of profiles among groups. Using rodent brain, the effects of postmortem delay or age were examined. Postmortem delay produced limited alterations to the profiles, but the effect of age was more pronounced. Many changes were apparent until 12 months, after which the profiles became more constant. Additional peptide profiling of the hippocampus demonstrated changes in peptide content as a function of perforant pathway ablation. The major strengths of HPLC-mediated peptide profiling are that it lends itself to automation and can be used to detect changes in peptides and small proteins among experimental groups or subjects without any prior assumptions concerning which ones might be altered.

Aged↗