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At least 235 records · Page 13Linked to original sources
PubMed1999

A computer simulation designed for problem-based learning.

OBJECTIVES: As problem-based learning is increasingly used in medical education, there is a growing need to capture the diversity of the events occurring during problem-based learning sessions in order to understand the way in which students learn. The computer simulation described attempts to analyse a posteriori how students reason and learn during such sessions. DESIGN: A computer simulation was designed to perform a detailed analysis of the following features: pattern of information searched, formulation of working hypothesis and identification of learning issues. The program, which has been running successfully for 2 years, was developed using local resources and accepts any clinical problem, provided it is written in a suitable text file format. The program has been applied in the discipline of pathophysiology. SETTING: Faculty of Medical Sciences of Lisbon, Portugal. SUBJECTS: Medical students. RESULTS: An example is presented of how prints were analysed in order to evaluate the 'progression profile' of the students, and a comparison is made with other similar instruments. CONCLUSIONS: The program improved understanding of the relationships between the inquiry strategy and hypothesis formulation and also of how self-learning (triggered by learning issues) influenced further analysis of the cases.

Computer Simulation↗
PubMedDate not supplied

A computer system designed for a hospital transfusion service.

A computer system that enhances the efficiency of a hospital transfusion service is described. It reduces the possibility of clerical errors; shortens the time elapsed between the ordering and the delivery of blood products; decreases the outdating of these units; and provides easy access to medical, demographic, and statistical information.

Blood Banks↗
PubMed2003

Biomechanical stresses in computer-aided design and in data entry.

A study of the risk factors of musculoskeletal disorders (MSDs) of the upper limbs was carried out on 2 populations, 1 performing a computer-aided design (CAD) task and the other performing a data entry task. A questionnaire on MSD complaints and working life was completed by a sample of each population. Biomechanical measurements of the forces, the angles, and the repetitiveness of movements of the upper limbs were carried out on some operators in each sample. It emerged that complaints of the upper limbs seem to be linked to the use of input devices. The grip forces exerted when using the keyboard and mouse were higher in CAD than in data entry.

Adult↗
PubMed1996

Computer-aided design of bioerodible devices with optimal release characteristics: a cellular automata approach.

The development of a computational tool to design bioerodible devices with optimal release characteristics is presented. This computational tool uses cellular automata and parallel iterations to model and simulate the release of bioactive agents (drugs) from bioerodible matrices. The simulations can accurately model surface erosion processes in multicomponent systems of arbitrary geometry and with different dissolution rates for each component. Simulation results are analysed to show how the overall release rates are affected by the intrinsic dissolution rates, drug loading, porosity and the dispersion of the drug in the bioerodible matrix. A strongly non-linear dependence of release rates on drug loading and the intrinsic dissolution rates of the solid components is obtained and the effects of phase dispersion on the variability of release rates are elucidated. Finally, guidelines are presented for screening of alternatives to minimize the development effort and experimentation required for designing devices with desired release characteristics.

Biocompatible Materials↗
PubMed2005

Three-dimensional computer-aided design based design sensitivity analysis and shape optimization of the stem using adaptive p-method.

The number of stem designs for total hip arthroplasty is increasing, and occasionally design changes have yielded unexpected clinical results. At present, we are not able to clearly identify which parameter of the stem is most important, and the optimum value of many parameters. The goals of this study were to identify which parameter is most important, to understand the effect of design change, and to find the optimum stem shape. For this purpose, we used adaptive p-method together with three-dimensional computer-aided design software program for the design sensitivity analysis (DSA) and shape optimization of the stem. The results suggested that increasing the lateral and medial width of the distal cross-section together with decreasing the medial-lateral width and the medial radius of the distal cross-section from the default value would lead to a decrease in the largest maximum principal stress of the distal cement. The medial width of middle cross-section, however, was not so simple. The result of DSA suggested that decreasing this parameter from the default value decreased the stress in the distal cement, but the optimum shape was obtained by increasing this parameter. The method used in this study will assist our engineers and surgeons in the process of modifying and optimizing the stem design.

Arthroplasty, Replacement, Hip↗
PubMed2001

Validation of a software designed for computed tomographic (CT) measurement of lung water.

OBJECTIVE: The in-vitro validation of a computed tomographic (CT) software specifically designed for quantifying the volume of water contained in the lung. DESIGN: An in-vitro, ex-vivo study. In 1993, a postmortem left pneumonectomy was performed in a patient who died from acute respiratory distress syndrome. The lung was fixed, inflated and dried according to a technique proposed by Markarian and Dailey in 1975 aimed at producing a lung specimen spongy in texture and suitable for radiography. MEASUREMENTS AND RESULTS: In 1999, 13 CT scans of this lung specimen were performed corresponding to different bronchial instillations of known volumes of water and albumin 4%. The different lung weights resulting from the successive bronchial instillations were calculated using a specially designed software, Lungview, adapted for CT measurements and compared with the actual lung weight measured by an electronic scale. The increase in lung weight measured by Lungview was closely correlated with the actual increase in lung weight resulting from bronchial instillation of water and albumin (y = 0.99x - 23, r = 1 for water and y = x - 17, r = 1 for albumin 4%) and the precision of the bias was 7 g for water and 3 g for albumin 4%. CONCLUSIONS: This study shows that the CT software Lungview accurately measured the volume of lung water present within an air-dried exsanguine human lung.

Aged↗
PubMed2004

[Fabrication of custom-made artificial semi-knee joint based on rapid prototyping technique: computer-assisted design and manufacturing].

OBJECTIVE: To design a new custom-made artificial semi-knee joint based on rapid prototyping(RP) technique and to explore a method to solve necroses of allocartilage in hemi-joint allotransplantation. METHODS: Based on the extracted 3D contour image of the articular cartilage of femoral condyle, the custom-made artificial semi-knee joint was designed with Surfacer 9.0 image processing software. The artificial semi-knee joint design used the femoral condylar 3D contour of the patient as the outer face and the subchondral bone 3D contour of allograft bone as inner face. One dado for medullary nail and two for special designing cages which were used to fix the cartilage into the allograft were added on the inner face. After being converted into RP data format, the computer-assisted design was imported into the LPS600 rapid prototyping machine, and the prototype was achieved. Furthermore, the prototype could be modified by hand according to the design. Then the RP model was used as a positive mould to build up a silica gel negative mould, and the negative mould was sent to the factory to manufacture Ti-6A1-4V alloy articular cartilage through ordinary mould-melted founding process. Finally, the whole metal cartilage was completed after melting two special cages on it and polishing it. RESULTS: A new custom-made artificial semi-knee joint was made and used to treat a 14-year old patient. The custom-made artificial semi-knee joint and the subchondral bone were a perfect match. The operative result was satisfactory. The patient could walk 5 weeks after operation. The bone healing of the auto-bone and allo-bone was achieved 6 months later. A follow-up period lasting 1 year showed that the knee joint played a good function. CONCLUSION: The artificial semi-knee joint is a good match for the allograft bone and a good idea to solve necroses of allocartilage in hemi-joint allotransplantation.

Adolescent↗
PubMedDate not supplied

Software for experimental design: the computer program EXCAD.

A computer program (EXCAD) dedicated to the optimization of experimental designs to estimate parameters of a mathematical model, is presented. EXCAD computes D-optimal designs and sequentially augmented designs. D-optimal designs minimize the determinant of the variance-covariance matrix and parameters, thus obtaining the average most accurate estimate of parameters. D-optimal designs have generally as many support points as the number of parameters in the mathematical model, so sample scheduling is minimal, not extensive. Augmented designs add to an original design the point that maximizes the decrement of the determinant of the variance-covariance matrix. The general model, linearly or not linearly parametrized Y = F(X,P), that relates two independent variables and P parameters to different responses may be written in the program, while a set of prewritten models is provided.

Algorithms↗
PubMed1988

Computer aided design and evaluation of limiting and serial dilution experiments.

Two computer programs are presented which can be used for the determination of the design and the statistical evaluation of data in the context of limiting and serial dilution analysis. The first program (DESIGN) gives the experimenter the opportunity to set up different designs, to improve a design according to several suggestions, to make a picture of a design and to evaluate the results of artificial data, obtained from a random experiment corresponding with the chosen design, until (s)he is convinced of having a suitable design for a particular experiment. The second program (EVALUATE) evaluates the experimental data. The design method and the statistical methods used in the programs have been chosen on practical and theoretical grounds.

Colony Count, Microbial↗
PubMed1999

A prospective study of computer-aided design and manufacture of titanium plate for cranioplasty and its clinical outcome.

The use of computerized three dimensional imaging and automated milling of models to produce accurate titanium plates for the reconstruction of craniofacial defects is described. A total of 148 patients have had extensive calvarial defects repaired using this (computer aided design and manufacture) technique developed in our unit. Of these, 141 were repaired secondarily (delayed cranioplasty), whilst seven were repaired immediately following craniectomy (single stage cranioplasty). All cases were assessed for accuracy of fit, restoration of natural skull contour and aesthetics. Seventy-two patients were reviewed after 1 year to determine the effect on adverse preoperative symptoms. Of the plates 97% had an excellent or good intraoperative fit. The modal insertion time was only 15 minutes. Postoperatively 98% resulted in the restoration of natural skull shape and symmetry. After 1 year, 82% of patients had complete resolution or diminution in severity of the adverse symptoms. A staphylococcus infection necessitated the temporary removal of one plate.

Adolescent↗
PubMed2006

High-resolution structural and thermodynamic analysis of extreme stabilization of human procarboxypeptidase by computational protein design.

Recent efforts to design de novo or redesign the sequence and structure of proteins using computational techniques have met with significant success. Most, if not all, of these computational methodologies attempt to model atomic-level interactions, and hence high-resolution structural characterization of the designed proteins is critical for evaluating the atomic-level accuracy of the underlying design force-fields. We previously used our computational protein design protocol RosettaDesign to completely redesign the sequence of the activation domain of human procarboxypeptidase A2. With 68% of the wild-type sequence changed, the designed protein, AYEdesign, is over 10 kcal/mol more stable than the wild-type protein. Here, we describe the high-resolution crystal structure and solution NMR structure of AYEdesign, which show that the experimentally determined backbone and side-chains conformations are effectively superimposable with the computational model at atomic resolution. To isolate the origins of the remarkable stabilization, we have designed and characterized a new series of procarboxypeptidase mutants that gain significant thermodynamic stability with a minimal number of mutations; one mutant gains more than 5 kcal/mol of stability over the wild-type protein with only four amino acid changes. We explore the relationship between force-field smoothing and conformational sampling by comparing the experimentally determined free energies of the overall design and these focused subsets of mutations to those predicted using modified force-fields, and both fixed and flexible backbone sampling protocols.

Carboxypeptidases A↗
PubMed2004

Fabrication of a maxillofacial prosthesis using a computer-aided design and manufacturing system.

PURPOSE: Maxillofacial prostheses are usually fabricated on the basis of impressions made with dental-impression material. The extent to which the prosthesis reproduces normal facial morphology depends on the clinical judgment of the individual fabricating the prosthesis. This paper describes a computer-aided design and manufacturing (CAD/CAM) system for the fabrication of maxillofacial prostheses. This system will provide a more consistently accurate reproduction of facial morphology. MATERIALS AND METHODS: Facial measurements were taken using a non-contact three-dimensional laser morphological measurement system. The measurements were sent to a computer numerical controlled (CNC) milling machine to generate a cast of the patient's face for the fabrication of prosthesis. RESULTS: Facial contours were measured using a laser. This method minimizes patient discomfort and avoids soft tissue distortion by impression material. Moreover, the digital data obtained is easy to store and transmit, and mirror-images can be readily generated by computer processing. CONCLUSION: This method offers an objective, quantified approach for fabricating maxillofacial prostheses.

Computer-Aided Design↗
PubMedDate not supplied

[Computer-assisted design in removable partial dentures. Expert system and software for framework tracing].

Stelligraph, a software program for designing the removable partial denture offers many possibilities in computer assisted technology. The design can be realized on any particular case, based on three different concepts. This software program can also provide on individual, manual and personalized design this offening complete freedom in the conception. This software program is an expert system in removable partial denture by providing the general practitioner with a rational design as well as clinical guidance for oral rehabilitation.

Denture Design↗
PubMed2006

Computer-aided design of agents that inhibit the cep quorum-sensing system of Burkholderia cenocepacia.

Recent research has provided evidence that interference with bacterial cell-to-cell signaling is a promising strategy for the development of novel antimicrobial agents. Here we report on the computer-aided design of novel compounds that specifically inhibit an N-acyl-homoserine lactone-dependent communication system that is widespread among members of the genus Burkholderia. This genus comprises more than 30 species, many of which are important pathogens of animals and humans. Over the past few years, several Burkholderia species, most notably Burkholderia cenocepacia, have emerged as important opportunistic pathogens causing severe pulmonary deterioration in persons with cystic fibrosis. As efficient treatment of Burkholderia infections is hampered by the inherent resistance of the organisms to a large range of antibiotics, novel strategies for battling these pathogens need to be developed. Here we show that compounds targeting the B. cenocepacia signaling system efficiently inhibit the expression of virulence factors and attenuate the pathogenicity of the organism.

Anti-Bacterial Agents↗
PubMed1984

A DNA analysis program designed for computer novices working in an industrial-research environment.

A program designed for DNA sequence analysis by people with no computer background or experience is described. The criteria used in the program design were (i) user friendliness, (ii) ability to handle large DNA files (greater than 10 kilobases), (iii) low storage requirements so that it could be put on a personal computer (IBM), (iv) written in a widely used language (FORTRAN 77) and (v) ability to handle all of the needed tasks for DNA analysis. The program consists of an executive that controls a set of modular subprograms. A file management system using 'SEQ' and 'SITE' files is also in place. SEQ files contain long DNA nucleotide sequences (e.g. restriction enzyme sites). Related SEQ and SITE files are grouped into categories. A SITE category can include related sequences a user wishes to search for in a longer SEQ sequence from a designated category. For example, all of the restriction enzyme recognition sites can group into a single category called 'Enzymes' and can be searched for in a SEQ sequence which has been placed in the SEQ file category 'Plasmids'. Colour graphics is also used as a visual aid.

Base Sequence↗
PubMedDate not supplied

[Software and hardware for computer equipment designed for psychophysiological examination].

Principles of designing software and hardware for new computer equipment for psychophysiological examination were elaborated on the basis of theoretical prerequisites and of analysis of the use of equipment manufactured serially for quantitation of indices of the human higher nervous activity (HNA). The hierarchic structuring of software and hardware enabled, through unification of solutions, the development of new modifications of two equipment sets: computer-based unit "Psihomat" KPFK-99 for psychophysiological examination and computer-based unit "STABILOTEST" ST-01 for the evaluation of the central nervous system by the stability parameters in maintaining the vertical posture. The units have new improved functional features and provide the users with new computer technologies for dealing with research and practical tasks related with examination of human HNA parameters in health and pathology.

Computers↗
PubMed2006

Computer-aided design and fabrication of dental restorations: current systems and future possibilities.

BACKGROUND: For more than 20 years, researchers have been trying to automate conventional manual processes in dental technology with the hope of producing higher- and more uniform-quality materials, standardizing manufacturing processes and reducing production costs. METHODS: The authors review existing computer-aided design (CAD)/computer-aided manufacturing (CAM) systems, describing the components of CAD/CAM technologies and addressing the limitations of current systems, and suggest possibilities for future systems. CONCLUSIONS: Existing dental CAD/CAM systems vary dramatically in their capabilities; each has distinct advantages and limitations. None can yet acquire data directly in the mouth and produce the full spectrum of restoration types (with the breadth of material choices) that can be created by traditional techniques. Emerging technologies may expand dramatically the capabilities of future systems, but they also may require a different type of training to use them to their full effectiveness. CLINICAL IMPLICATIONS: In the future, automatically fabricated, fully esthetic restorations might be produced more quickly and have longer lifetimes than restorations currently produced with CAD/CAM systems.

Computer-Aided Design↗
PubMed1985

Computer-assisted design of butterfly bileaflet valves for the mitral position.

This paper describes the application of computer testing to a design study of butterfly bileaflet mitral prostheses having flat or curved leaflets. The curvature is in the plane normal to the pivot axes and is such that the convex sides of the leaflets face each other when the valve is open. The design parameters considered are the curvature of the leaflets and the location of the pivot points. In this study, stagnation is assessed by computing the smallest value (over the three openings of the valve) of the peak velocity, and hemodynamic performance is judged by a benefit/cost ratio: the net stroke volume divided by the mean transvalvular pressure difference. Unlike the case of a pivoting single-disc valve, the inclusion of a constraint on the maximum angle of opening of the leaflets is found to be essential for adequate, competent performance. Results are presented with both 85 degrees and 90 degrees constraints, since best performance is achieved with the opening-angle constraint in this range. Asymmetry of leaflet motion which is observed with flat leaflets in the mitral position is reduced with modest leaflet curvature. Leaflet curvature also ameliorates central orifice stagnation, which is observed with flat leaflets. Curvature of the valve produces the following improvements in comparison with the best flat valve when the opening-angle constraint is 85 degrees: a 38% increase in the minimum peak velocity and a 16% increase in the hemodynamic benefit/cost ratio. With a 90 degrees constraint the corresponding improvements are 34% and 20%, respectively.

Computers↗