SEARCH · Search PubMed

Results for “Computers”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,711 records · Page 95Linked to original sources

PubMed2003

A computationally inexpensive modification of the point dipole electrostatic polarization model for molecular simulations.

We present an approximation, which allows reduction of computational resources needed to explicitly incorporate electrostatic polarization into molecular simulations utilizing empirical force fields. The proposed method is employed to compute three-body energies of molecular complexes with dipolar electrostatic probes, gas-phase dimerization energies, and pure liquid properties for five systems that are important in biophysical and organic simulations-water, methanol, methylamine, methanethiol, and acetamide. In all the cases, the three-body energies agreed with high level ab initio data within 0.07 kcal/mol, dimerization energies-within 0.43 kcal/mol (except for the special case of the CH(3)SH), and computed heats of vaporization and densities differed from the experimental results by less than 2%. Moreover, because the presented method allows a significant reduction in computational cost, we were able to carry out the liquid-state calculations with Monte Carlo technique. Comparison with the full-scale point dipole method showed that the computational time was reduced by 3.5 to more than 20 times, depending on the system in hand and on the desired level of the full-scale model accuracy, while the difference in energetic results between the full-scale and the presented approximate model was not great in the most cases. Comparison with the nonpolarizable OPLS-AA force field for all the substances involved and with the polarizable POL3 and q90 models for water and methanol, respectively, demonstrates that the presented technique allows reduction of computational cost with no sacrifice of accuracy. We hope that the proposed method will be of benefit to research employing molecular modeling technique in the biophysical and physical organic chemistry areas.

Algorithms↗

PubMed2003

Development of hardware accelerator for molecular dynamics simulations: a computation board that calculates nonbonded interactions in cooperation with fast multipole method.

Evaluation of long-range Coulombic interactions still represents a bottleneck in the molecular dynamics (MD) simulations of biological macromolecules. Despite the advent of sophisticated fast algorithms, such as the fast multipole method (FMM), accurate simulations still demand a great amount of computation time due to the accuracy/speed trade-off inherently involved in these algorithms. Unless higher order multipole expansions, which are extremely expensive to evaluate, are employed, a large amount of the execution time is still spent in directly calculating particle-particle interactions within the nearby region of each particle. To reduce this execution time for pair interactions, we developed a computation unit (board), called MD-Engine II, that calculates nonbonded pairwise interactions using a specially designed hardware. Four custom arithmetic-processors and a processor for memory manipulation ("particle processor") are mounted on the computation board. The arithmetic processors are responsible for calculation of the pair interactions. The particle processor plays a central role in realizing efficient cooperation with the FMM. The results of a series of 50-ps MD simulations of a protein-water system (50,764 atoms) indicated that a more stringent setting of accuracy in FMM computation, compared with those previously reported, was required for accurate simulations over long time periods. Such a level of accuracy was efficiently achieved using the cooperative calculations of the FMM and MD-Engine II. On an Alpha 21264 PC, the FMM computation at a moderate but tolerable level of accuracy was accelerated by a factor of 16.0 using three boards. At a high level of accuracy, the cooperative calculation achieved a 22.7-fold acceleration over the corresponding conventional FMM calculation. In the cooperative calculations of the FMM and MD-Engine II, it was possible to achieve more accurate computation at a comparable execution time by incorporating larger nearby regions.

Algorithms↗

PubMed2004

Computer treatment for common mental health problems.

Perhaps the most complex and controversial role for the computer in clinical practice is as a treatment medium in which the computer effectively replaces the psychotherapist. This article outlines the historical development of computer treatment, from dialogue generators in the 1960s through to the interactive, multimedia programs of the 2000s. In evaluating the most recent developments in computer treatment, we present a small meta-analytic study demonstrating large effect sizes in favor of computer treatments for anxiety and depression for pre/post outcomes and treatment as usual/waitlist comparators. Next, we review studies of the cost effectiveness of computer treatments. Finally, we outline the implications for research, policy, and practice of this new generation of treatment options.

Anxiety Disorders↗

PubMed2006

Accurate quantification of visceral adipose tissue (VAT) using water-saturation MRI and computer segmentation: preliminary results.

PURPOSE: To describe and evaluate the accuracy of water-saturation MRI and a computer segmentation program for quantification of visceral adipose tissue (VAT). MATERIALS AND METHODS: MRI was performed on five patients with whole-volume coverage of the abdomen using two different sequences: 1) a T1-weighted spoiled gradient-echo breath-hold sequence (non-water-saturation) and 2) a T1-weighted spoiled gradient-echo water-saturation breath-hold sequence (water-saturation). The computer segmentation program analyzed the data and calculated VAT volumes (cm3) from both sequences. The data from one patient were additionally processed with the use of a manual technique. The intrastudy reproducibility of the proposed method using the water-saturation MRI sequence and the computer segmentation technique was tested by repeated measures of the automated system analysis (x 10) on MRI data from a single subject to calculate variability. RESULTS: VAT volumes measured by the water-saturation MRI sequences were consistently greater than those measured by the non-water-saturation sequences. Comparison of VAT volumes derived from the water-saturation images and measured by the computer segmentation technique vs. the manual technique showed good correlation (K = 0.8), with a significant time-saving benefit associated with the automated method (5 minutes vs. 1 hour). There was poor correlation between VAT volume measurement calculated by the manual technique and the computer segmentation technique using non-water-saturation images. The reproducibility of the computer segmentation technique using data derived from water-saturation images was high, with a low variability (+/- 5%). CONCLUSION: The results obtained demonstrate that the proposed method may be able to provide accurate quantification of VAT in a highly reproducible and efficient manner.

Body Water↗

PubMed2006

Retrieval, experimental, and computational assessment of the performance of total knee replacements.

Wear mechanisms in polyethylene components for total knee replacements are inherently mechanical; the local stresses or strains exceed some material limit. Retrieval analysis and knee simulators have provided the means to quantify the damage observed in vivo or in vitro. These results have been circumstantially linked to the material stresses obtained from computational simulations using finite element analysis, knee simulator tests, and computational simulations of two condylar knee designs. We hypothesize that if an equivalent loading environment is produced in the computational simulation, we can correlate the distribution of computed stresses with observed damage of simulator specimens and further relate design differences to in vivo performance from retrieval analyses. The finite element model agreed with the knee simulator kinematics and kinetics within 2-13%, and composite FEA contact areas matched 66-90% of the damage areas due to burnishing on the simulator specimens. Burnishing was the primary mode of damage for both the simulator and retrieval specimens corresponding with the relatively low magnitudes of contact stress observed. Both the computational and experimental techniques underpredicted the amount determined from retrieval analysis, but the differences between the two designs were consistent for all three methods. Combining these techniques strengthens the applicability of the computational simulation while highlighting the complementary approach of these methods for preclinical testing and assessing the link between material state and damage.

Arthroplasty, Replacement, Knee↗

PubMed1993

Multiple-site titration and molecular modeling: two rapid methods for computing energies and forces for ionizable groups in proteins.

Computer models of proteins frequently treat the energies and forces associated with ionizable groups as if they were purely electrostatic. This paper examines the validity of the purely electrostatic approach, and concludes that significant errors in energies can result from the neglect of ionization changes. However, a complete treatment of ionizable groups presents substantial computational obstacles, because of the large number of ionization states which must be examined in systems having multiple interacting titratable groups. In order to address this problem, two novel methods for treating the energetics and forces associated with ionizable groups with a minimum of computer time have been developed. The most rapid method yields approximate energies by computing the free energy of a single highly occupied ionization state. The second method separates ionizable groups into clusters, and treats intracluster interactions exactly, but intercluster interactions approximately. This method yields both accurate energies and fractional charges. Good results are obtained in tests of both methods on proteins having has many as 123 ionizable groups. The more rapid method requires computer times of 0.01 to 0.34 sec, while the more accurate method requires 0.7 to 15 sec. These methods may be fast enough to permit the incorporation of ionization effects in iterative computations, such as energy minimizations and conformational searches.

Animals↗

PubMed2000

Peer teaching and computer-assisted learning: An effective combination for surgical skill training?

BACKGROUND: The surgical literature suggests that collaborative learning using peers may be a valid way to teach surgical skills and there is a growing interest in the use of computer-assisted learning for this purpose. Combining this evolving technology with this type of teaching would theoretically offer a number of advantages including a reduction in the amount of faculty time devoted to this task. In this study, we evaluate the efficacy of a type of collaborative learning in a computer-assisted learning environment. MATERIALS AND METHODS: We designed a prospective, randomized study comparing novice learners who were allowed to work in pairs with those who worked independently in a specially equipped computer-assisted learning classroom. Both pretest and posttest assessments were performed by videotaping this skill. Three experts then evaluated the videotapes, in a blinded fashion. Three different outcomes were assessed. RESULTS: Seventy-seven subjects were enrolled in and completed the study. Comparison of the outcome measures demonstrated no between group difference in the average performance scores or posttest times. The proportion of subjects who correctly tied a square knot was significantly lower in the computer-assisted peer teaching group when compared with the computer-assisted learning alone group (P = 0.04). CONCLUSIONS: Collaborative learning in a computer-assisted learning environment is not an effective combination for teaching surgical skills to novices.

Computer-Assisted Instruction↗

PubMed1986

Computed tomography and plain radiography in experimental fracture healing.

We evaluated the relative contribution of plain radiographs and computed tomography to the assessment of fracture healing under experimental circumstances. In 15 sheep, we performed midshaft femoral osteotomies and internal fixation of the resultant segmental fractures. Radiographs were obtained preoperatively and immediately postoperatively. Animals were sacrificed at 3 weeks, 6 weeks, 12 weeks, 24 weeks, and 36 weeks after surgery, and the femoral specimens radiographed. After removal of the internal fixation devices, computed tomographic scans of the specimens were performed. By 3 weeks, callus was visible, but at 6 weeks, a trabecular pattern in the callus was seen on plain films but not on computed tomography. There was progressive organization of the callus on both studies. At 24 weeks, computed tomography demonstrated fracture lines not seen due to overlying callus on plain films and also more accurately showed incomplete union. By 36 weeks, healing was essentially complete according to both modalities, although there still were small gaps in the callus detectable on computed tomography but not on plain films. Computed tomography may be of value in the evaluation of fractures of long bones in those cases in which clinical examination and plain radiographs fail to give adequate information as to the status of healing.

Animals↗

PubMed1975

Computer-aided diagnosis of "dyspepsia".

Experience with computer-aided diagnosis of "dyspepsia" in a consecutive prospective series of 212 patients coming to surgery is described. Analysis is concentrated upon 122 patients who presented to an outpatient clinic de novo for diagnosis. During their first (outpatient) hospital contact, a firm diagnosis was made in just over half of these patients (though where made, it was usually correct). After full investigation, the diagnostic accuracy (prior to operation) was 92.6%. Using data elicited solely from the house surgeon's interview at the time of admission, the computer's overall diagnostic accuracy was 87.7%. The cost of each new computer diagnosis was around 25 new pence ($0.60). and the time taken was about 5 minutes. In a further small series designed to discriminate between organic and functional dyspepsia, the computer correctly assigned all but 1 of 23 patients with organic disease to the correct disease category. However, almost half of 33 patients with x-ray negative dyspepsia were predicted by the computer to have organic lesions. Time alone will tell whether the computer is a better early predictor of eventual organic disease than currently available radiologic methods.

Bayes Theorem↗

PubMed1993

Computational logic: a method for formal analysis of the ICU knowledge base.

The object of clinical computing is to support the making of clinical decisions. This takes place in an integrated context of care that involves processes of three different kinds: (1) the physiologic processes in the patient, (2) the processes of physiologic data as stored in, and moved within, a distributed computing system, and (3) the therapeutic and decision-making processes of the clinical staff. The clinical computing system is complex, and as we press it further to work as a partner in the complete care context, it tends to become unmanageably so. In this article, we try to suggest how one might begin using a formal mathematical theory, called 'computational logic,' to give theoretical analyses that might help one to understand the computing system and thereby to try to increase its ability to meet demands on it, and might help one to understand the care context as a whole. We examine the three levels, one at a time, looking for structural analogies between them, and trying to identify the ways that they are linked together. Computational logic provides us with a common set of notions for doing so.

Artificial Intelligence↗

PubMed1989

Computers in medicine: liability issues for physicians.

Physicians routinely use computers to store, access, and retrieve medical information. As computer use becomes even more widespread in medicine, failure to utilize information systems may be seen as a violation of professional custom and lead to findings of professional liability. Even when a technology is not widespread, failure to incorporate it into medical practice may give rise to liability if the technology is accessible to the physician and reduces risk to the patient. Improvement in the availability of medical information sources imposes a greater burden on the physician to keep current and to obtain informed consent from patients. To routinely perform computer-assisted literature searches for informed consent and diagnosis is 'good medicine'. Clinical and diagnostic applications of computer technology now include computer-assisted decision making with the aid of sophisticated databases. Although such systems will expand the knowledge base and competence of physicians, malfunctioning software raises a major liability question. Also, complex computer-driven technology is used in direct patient care. Defective or improperly used hardware or software can lead to patient injury, thus raising additional complicated questions of professional liability and product liability.

Decision Making, Computer-Assisted↗

PubMed1995

Cardiac output measurement by the thermodilution method: an in vitro test of accuracy of three commercially available automatic cardiac output computers.

OBJECTIVE: To describe the accuracy and the reproducibility of the thermodilution flow measurements obtained using 3 commercially available cardiac output computers commonly used in intensive care units. DESIGN: An experimental "in vitro" study. Twelve different values of control flow (Qctr) were measured (Qmsr) using 3 different cardiac output computers (Abbott Critical Care System, Oximetrix 3 SvO2/CO Computer, Baxter Oximeter/Cardiac Output Computer SAT-1; American Edwards Laboratories, 9520 A Cardiac Output Computer). Standard equipment and techniques were employed, taking account of the specific weight and heat of warm water relative to blood. In addition, separate sets of measurements were performed in order to investigate the effect on Qmsr of some variables which may influence the "indicator" loss (time for injection, depth of immersion of the catheter, temperature of the injected fluid). SETTING: Our laboratory, inside the intensive care unit. MEASUREMENTS AND RESULTS: The analysis of the linear regression of Qmsr versus Qctr (r values between 0.992 and 0.984; residual standard deviation values comprised between 0.24 and 0.49 l/min; intercepts and slopes not significantly different from identity line), the values of the percentage errors (PE = [Qctr-Qmsr].100/Qctr; PE mean values 7.9, 5.0 and 13.1), and those of the coefficients of variability (CV = standard deviation mean value, %; CV mean values 5.4, 5.8 and 4.6), show a good level of accuracy and reproducibility of the measurements. Our data confirm previously reported results. Furthermore, the cumulative effect of variables capable of influencing the "indicator" loss, even if corrected according to the "calculation constant" the manufacturers provide, was found to result in statistically significant changes of Qmsr. CONCLUSION: The accuracy and reproducibility of the automatic cardiac computers tested is sufficient for practical clinical purpose. It may also depend on the modality of injection of the cooling bolus, which may significantly influence the effective "indicator" losses.

Cardiac Output↗

PubMed1992

Computer assisted design of a theophylline dosing regimen in acute bronchospasm: serum concentrations and clinical outcome.

The effect of intravenous theophylline on the outcome of inhospital treatment of acute bronchospasm has been assessed, comparing the results achieved by computer-assisted dosing, designed to achieve and maintain a serum theophylline level of 16 micrograms.ml-1 (10 patients) with those of unaided physicians (15 control patients). The outcome measures compared were clinical improvement, peak expiratory flow rate and serum theophylline concentration. Loading doses of theophylline in the control and computer groups were: 167 and 437 mg, respectively. Initial serum theophylline concentrations, measured 20 min after the loading dose, were 13.6 and 17.0 micrograms.ml-1 in the control and computer groups, respectively. In patients who had not received theophylline prior to admission, loading doses and initial concentrations were: 200 mg and 9.4 micrograms.ml-1 in the control group (n = 5) versus 613 mg and 15.7 micrograms.ml-1 in the computer group (n = 4), respectively. During maintenance therapy, serum theophylline concentrations were kept in the therapeutic range (10-20 micrograms.ml-1) throughout 51% and 77% of the hospitalisation period, in the control and computer groups, respectively. There were no differences between the two groups in the rate or extent of clinical improvement or in change in peak expiratory flow rate. The computer assisted theophylline dosing regimen outperformed that of the unaided physicians in achieving and maintaining therapeutic serum theophylline concentrations in acute bronchospasm. There was no correlation between clinical outcome and serum theophylline concentration, but this may have been due to the small sample size and modest difference in serum theophylline between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1984

Computer literacy in today's medical center environment.

The need for computer literacy is becoming increasingly important across the broad scope of the American work scene. At the Wilford Hall USAF Medical Center (WHMC) numerous computer systems have been introduced into the operational environment. Training for these systems has been restricted primarily to transaction processing and routine report generation for those actually involved as users of these systems. WHMC has developed and implemented a broad computer literacy program designed generally to raise the computer literacy of the overall staff, and specifically to inform executive and middle management of the general capabilities of the computer systems. The program consists of a brown-bag lunchtime videotape theater on a series of computer-related subjects as well as formal classes developed in a modular format. Each formal class is tailored to the specific needs of the target executive or middle-management group.

Administrative Personnel↗

PubMed1984

Computer technology for autistic students.

The first purpose of this article is to review the literature related to the use of computers with autistic individuals. Although only a limited number of applications have been reported, the potential of the computer to facilitate the progress of autistic persons is promising. The second purpose is to identify specific learning problems or styles associated with autism from the research literature and link these with the unique aspects of computer-based instruction. For example, the computer's role in improving the motivation of autistic individuals is related to its capacity to analyze the reinforcing qualities of a particular event interactively and immediately for each user. Finally, recommendations that may enable computers to be maximally beneficial in assessing the learning process and remediating learning problems are offered. Two such recommendations are selecting appropriate software and integrating computer instruction within the classroom environment.

Attention↗

PubMed2004

Full scale computer simulators in anesthesia training and evaluation.

PURPOSE: With the advent of competency-based curriculum, technology such as full scale computer simulators have acquired an increasingly important role in anesthesia both in training and evaluation. This article reviews the current role of full scale computer simulators in teaching and evaluation in anesthesia. SOURCE: This review draws from existing anesthesia and medical education literature in order to examine and assess the current role of full scale computer simulators in anesthesia education today. PRINCIPAL FINDINGS: The last decade has witnessed a major increase in the use of full scale computer simulators in anesthesia. Many applications have been found for these simulators including teaching and training, evaluation and research. Despite the increasing use and application of full scale computers in anesthesia in the area of teaching and training, definitive studies evaluating its cost effectiveness, its efficacy compared to traditional training methods or its impact on patient outcome are still pending. Although there is some preliminary evidence of reliability and validity in using the simulator to evaluate clinical competence, development in this area has not progressed enough to justify its use in formal, summative evaluation of competence in anesthesia at this time. CONCLUSIONS: As technology acquires an increasingly important role in medical education, full scale computer simulators represent an exciting potential in anesthesia. However, the full potential and role of simulators in anesthesia is still in development and will require a dovetailing of clinical theory and practice with current research in medical education.

Anesthesiology↗

PubMed1993

Optimized algorithms for displaying 16-bit gray scale images on 8-bit computer graphic systems.

Most personal computers contain 8-bit graphic display hardware, whereas most medical gray scale images are stored at 16-bit per pixel integers. To display medical gray scale images on such computers, the 16-bit image data must be remapped into 8-bit gray scale images. This report presents the algorithms and computer code that allow very rapid 16-bit to 8-bit image data transformation. These algorithms are helpful in allowing personal computers with at least the performance of a Macintosh II (Apple Computer, Cupertino, CA) computer to function as low-end picture archiving communication systems or personal workstations.

Algorithms↗

PubMed2002

The emergency department versus the computer: which is the better electrocardiographer?

Electrocardiograms (ECGs) are frequently ordered in the pediatric emergency department (ED). Pediatric cardiologists are generally not asked to interpret every ECG; thus, ED patient management is often guided by the ED physicians' ECG interpretation. The objective of this study was to analyze the accuracy of ECG interpretation by ED physicians and a computer-generated interpretation and compare the two. A 12-month prospective study was performed in a pediatric ED. All patients (<22 years) who had an ECG in the ED were included. The ED physicians and the computer interpretation were compared to a reference standard. Each electrocardiographic diagnosis, as well as the ECG as a whole, was assigned to one of the following predetermined classes: I, normal sinus rhythm; II, minimal clinical significance; III, indeterminate clinical significance; IV, those of definite clinical significance. Both groups correctly interpreted all normal (class I) ECGs. The computer correctly interpreted approximately 75% of the class II and class III ECGs, whereas the ED physicians correctly interpreted 36% of both groups. For the class IV ECGs, both the computer and the ED physicians performed poorly, correctly interpreting just 14% and 28%, respectively. The computer proved to be more accurate than the ED physicians in interpreting ECGs of less than critical significance (classes II and III), but neither group was able to correctly interpret even a simple majority of the most significant abnormalities (class IV). We speculate that distributing the computer-generated interpretation to the ED physicians and formal review of all ED ECGs by a skilled interpreter may decrease the number of missed diagnoses.

Adolescent↗