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PubMed1985

The dendritic extent of motoneurons in frog brachial spinal cord: a computer reconstruction of HRP-filled cells. With comments on dendritic reconstruction methodologies.

A lateral and a medial motoneuron in the brachial spinal cord of the leopard frog, Rana pipiens, were labeled by horseradish peroxidase applied to the ventral root. Their dendritic trees were traced, analyzed, and plotted using a computer-microscope system. Some dendrites of the medial motoneuron crossed the midline of the spinal cord, but no dendrites of the lateral motoneuron crossed the midline. Nevertheless, the total dendritic length of the lateral motoneuron exceeded that of the medial motoneuron. The peak number of dendritic branch segments of the medial motoneuron was located at a greater distance from its soma than that of the lateral motoneuron. Three-dimensional reconstruction and rotation of the dendritic trees revealed that the dendrites of the medial motoneuron had a greater rostrocaudal extent than those of the lateral motoneuron. When compared to reports of Golgi-impregnated motoneurons, our results suggest that the HRP technique labels dendrites more completely. However, use of the HRP technique may introduce greater errors in the subsequent measurement of dendritic segments due to nonuniform tissue shrinkage.

Animals↗
PubMed1999

Application of two neural network paradigms to the study of voluntary employee turnover.

Two neural network paradigms--multilayer perceptron and learning vector quantization--were used to study voluntary employee turnover with a sample of 577 hospital employees. The objectives of the study were twofold. The 1st was to assess whether neural computing techniques offered greater predictive accuracy than did conventional turnover methodologies. The 2nd was to explore whether computer models of turnover based on neural network technologies offered new insights into turnover processes. When compared with logistic regression analysis, both neural network paradigms provided considerably more accurate predictions of turnover behavior, particularly with respect to the correct classification of leavers. In addition, these neural network paradigms captured nonlinear relationships that are relevant for theory development. Results are discussed in terms of their implications for future research.

Adult↗
PubMed1997

Mild head injury in children and adolescents: a review of studies (1970-1995).

In this article, the authors provide a comprehensive review of the research of mild head injury in children and adolescents from 1970 to 1995. Because of marked variability in methodologies across studies, a preliminary box-score tally was computed, without regard to studies' scientific or methodological merit. These results revealed 13 adverse, 18 null, and 9 indeterminate findings related to neuropsychological, academic, or psychosocial outcome. When studies were classified based on methodological merit, the stronger studies were generally associated with null outcomes across domains. However, a few of the less stronger neuropsychological studies (5 of 40) reported subthreshold and transitory alterations during the early postinjury period. At the present time, cautious acceptance of the null hypothesis is recommended until more definitive studies are conducted that address the problems raised in this review.

Achievement↗
PubMed1999

Outcomes of 4 methods of debridement using a decision analysis methodology.

OBJECTIVE: To compare the clinical efficacy of 4 debridement alternatives in pressure ulcer management. DESIGN: Nonexperimental design combining computer modeling and a decision analysis methodology. Data input into the model were derived from a literature review of the MEDLINE database for the years 1985 to 1995 (indexing terms: pressure ulcer, decubitus, economics, cost-effectiveness, and outcome) and a Delphi consensus process with an independent panel of 9 specialists in geriatric care. SETTING: Long-term care. PATIENTS: Hypothetical elderly female resident with a new full-thickness pressure ulcer (mild odor, minimal draining, no undermining, intact periulcer skin). INTERVENTIONS: The study patient underwent 1 month of therapy with each of 4 debridement methods: autolysis, wet-to-dry dressings, collagenase (Santyl) or fibrinolysin (Elase). MAIN OUTCOME: Specific clinical outcomes (time to clean wound bed, risk of infection) and relative cost-effectiveness of each debridement method were calculated. RESULTS: The likelihood of achieving a clean wound bed at 2 weeks was 70% for collagenase, 57% for fibrinolysin, 50% for autolysis, and 30% for wet-to-dry dressings. The total cost for 1 month of treatment was $610.96 for collagenase, $920.73 for autolysis, $986.38 for fibrinolysin, and $1,008.72 for wet-to-dry dressings. CONCLUSIONS: The study patient was most likely to have a clean wound bed after 2 and 4 weeks of treatment, less likely to need to switch debridement methods, and of equal or less likelihood of experiencing and infection and subsequent hospitalization when her wound was debrided with collagenase. Treatment with collagenase also resulted in the lowest total cost of treatment. Longer term, prospective studies using actual utilization data are needed to refine these estimates of the clinical and cost-effectiveness of each product.

Aged↗
PubMed1978

A protocol for the use of contrast enhancement in cranial computed tomography.

There is some confusion regarding the indications for and methodology of the use of contrast material in cranial computed tomography. Some authors recommend a nonenhanced scan in all cases, followed by an enhanced scan if indicated by the symptoms or the appearance of the unenhanced scan. Others have questioned the value of the nonenhanced scan in patients with tumor. The authors offer a protocol for the use of contrast material. Possible tumor patients are scanned with contrast material alone; other patients are scanned either (a) without contrast material or (b) both with and without contrast material, depending upon the most likely clinical diagnosis.

Adult↗
PubMed2005

Corrosion inhibitors: design, performance, and computer simulations.

The development of a methodology to predict the performance of a corrosion inhibitor (CI) using specific types of modeled and experimental surfaces and their subsequent estimation is presented. For previously reported imidazoline CIs, the theoretical partition coefficients and molecular volumes were calculated, providing a guide for molecular engineering of new imidazolines. The new CIs, N-[2-(2-alkyl-4,5-dihydroimidazol-1-yl)ethyl]alkylamides and N-[2-(2-alkyloylaminoethylamino)ethyl]alkylamides, were designed, prepared, and their theoretical partition coefficients and molecular volumes calculated. These indexes were correlated between tested and prototype CIs to select the best ones for the corrosion inhibition tests. The inhibition efficiencies were measured through potentiodynamic polarization curves (PPC), linear polarization resistance (LPR), and weight loss measurements (WLM) for SAE-1010 and SAE-1018 steels. The leading molecules were 1-(2-decylaminoethyl)-2-decylimidazoline and 1-(2-dodecylaminoethyl)-2-dodecylimidazoline with WLM efficiencies (steel 1010), of 62.8 and 78.9%, respectively. The efficiencies for the PPC/LPR tests (steel 1018) were 97 and 94%. To understand the mechanism of action of CIs, a simple model is suggested for the growth of self-assembled monolayers of CIs on a crystalline substrate. This model takes into account the amphiphilic nature of the inhibitor molecule on the adsorption process. Despite the simplicity of the model, the Monte Carlo simulations reproduce qualitatively many of the experimentally observed features involved in the formation of monolayers and provide a tentative explanation for the mechanism of corrosion inhibition.

Journal Article↗
PubMed1997

Quantitative analysis of electrophoresis data: novel curve fitting methodology and its application to the determination of a protein-DNA binding constant.

A computer program, GelExplorer, which uses a new methodology for obtaining quantitative information about electrophoresis has been developed. It provides a straightforward, easy-to-use graphical interface, and includes a number of features which offer significant advantages over existing methods for quantitative gel analysis. The method uses curve fitting with a nonlinear least-squares optimization to deconvolute overlapping bands. Unlike most curve fitting approaches, the data is treated in two dimensions, fitting all the data across the entire width of the lane. This allows for accurate determination of the intensities of individual, overlapping bands, and in particular allows imperfectly shaped bands to be accurately modeled. Experiments described in this paper demonstrate empirically that the Lorentzian lineshape reproduces the contours of an individual gel band and provides a better model than the Gaussian function for curve fitting of electrophoresis bands. Results from several fitting applications are presented and a discussion of the sources and magnitudes of uncertainties in the results is included. Finally, the method is applied to the quantitative analysis of a hydroxyl radical footprint titration experiment to obtain the free energy of binding of the lambda repressor protein to the OR1 operator DNA sequence.

Bacteriophage lambda↗
PubMed2003

Local influence analysis of structural equation models with continuous and ordinal categorical variables.

This paper proposes a method to assess the local influence of minor perturbations for a structural equation model with continuous and ordinal categorical variables. The key idea is to treat the latent variables as hypothetical missing data and then apply Cook's approach to the conditional expectation of the complete-data log-likelihood function in the corresponding EM algorithm for deriving the normal curvature and the conformal normal curvature. Building blocks for achieving the diagnostic measures are computed via observations generated by the Gibbs sampler. It is shown that the proposed methodology is relatively simple to implement, computationally efficient, and feasible for a wide variety of perturbation schemes. Two illustrative real examples are presented.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Direct computer recording of premature infants and nursery care: distress following two interventions.

Prematurely born neonates are born with an immature central nervous system. Temporal associates between care-giver interventions and infant biobehavioral responses can be recorded. A new methodology for continuous naturalistic computer-assisted recording of infants in nursery care is described. To illustrate a clinical implication of this recording, an infant's responses to two seemingly contrasted care-giver interventions were analyzed: chest physical therapy and close social interaction. There was significantly increased subtle as well as gross behavioral and physiologic distress following both chest physical therapy and close social interaction when compared with base line distress incidence. Perhaps timing of interventions is as consequential as their content toward safeguarding a preterm infant's developing autonomic regulation, motor patterns, and sleep/wake state.

Computers↗
PubMed1993

Molecular recognition analyzed by docking simulations: the aspartate receptor and isocitrate dehydrogenase from Escherichia coli.

Protein docking protocols are used for the prediction of both small molecule binding to DNA and protein macromolecules and of complexes between macromolecules. These protocols are becoming increasingly automated and powerful tools for computer-aided drug design. We review the basic methodologies and strategies used for analyzing molecular recognition by computer docking algorithms and discuss recent experiments in which (i) substrate and substrate analogues are docked to the active site of isocitrate dehydrogenase and (ii) maltose binding protein is docked to the extracellular domain of the receptor, which signals maltose chemotaxis.

Amino Acid Sequence↗
PubMed1997

Photorealistic speech agents and facially expressive robots.

In an ideal human-computer interface, the computer would be able to understand and use modalities such as speech, hearing, facial gestures and body language in as realistic and natural a manner as a human. This paper discusses two kinds of computer-to-human interaction techniques which involve computerizea facial gestures: the first is the graphics representation of the human face projected on a video display; the second is the physical embodiment of facial expressions using an android robot. These simulated facial gestures may be accompanied by computerized speech synthesis, voice recognition capability or machine vision for recognition of the facial expressions of the human viewer. The author reviews both major techniques, then discusses current and proposed applications of this methodology.

Computer Simulation↗
PubMed2006

Automated identification of cancerous smears using various competitive intelligent techniques.

In this study the performance of various intelligent methodologies is compared in the task of pap-smear diagnosis. The selected intelligent methodologies are briefly described and explained, and then, the acquired results are presented and discussed for their comprehensibility and usefulness to medical staff, either for fault diagnosis tasks, or for the construction of automated computer-assisted classification of smears. The intelligent methodologies used for the construction of pap-smear classifiers, are different clustering approaches, feature selection, neuro-fuzzy systems, inductive machine learning, genetic programming, and second order neural networks. Acquired results reveal the power of most intelligent techniques to obtain high quality solutions in this difficult problem of medical diagnosis. Some of the methods obtain almost perfect diagnostic accuracy in test data, but the outcome lacks comprehensibility. On the other hand, results scoring high in terms of comprehensibility are acquired from some methods, but with the drawback of achieving lower diagnostic accuracy. The experimental data used in this study were collected at a previous stage, for the purpose of combining intelligent diagnostic methodologies with other existing computer imaging technologies towards the construction of an automated smear cell classification device.

Artificial Intelligence↗
PubMedDate not supplied

Simulating smokers' acceptance of modifications in a cessation program.

Recent research has underscored the importance of assessing barriers to smokers' acceptance of cessation programs. This paper illustrates the use of computer simulations to gauge smokers' response to program modifications which may produce barriers to participation. It also highlights methodological issues encountered in conducting this work. Computer simulations were based on conjoint analysis, a consumer research method which enables measurement of smokers' relative preference for various modifications of cessation programs. Results from two studies are presented in this paper. The primary study used a randomly selected sample of 218 adult smokers who participated in a computer-assisted phone interview. Initially, the study assessed smokers' relative utility rating of 30 features of cessation programs. Utility data were used in computer-simulated comparisons of a low-cost, self-help oriented program under development and five other existing programs. A baseline version of the program under development and two modifications (for example, use of a support group with a higher level of cost) were simulated. Both the baseline version and modifications received a favorable response vis-à-vis comparison programs. Modifications requiring higher program costs were, however, associated with moderately reduced levels of favorable consumer response. The second study used a sample of 70 smokers who responded to an expanded set of smoking cessation program features focusing on program packaging. This secondary study incorporate in-person, computer-assisted interviews at a shopping mall, with smokers viewing an artist's mock-up of various program options on display. A similar pattern of responses to simulated program modifications emerged, with monetary cost apparently playing a key role. The significance of conjoint-based computer simulation as a tool in program development or dissemination, salient methodological issues, and implications for further research are discussed.

Adolescent↗
PubMed2003

Insights into nucleic acid conformational dynamics from massively parallel stochastic simulations.

The helical hairpin is one of the most ubiquitous and elementary secondary structural motifs in nucleic acids, capable of serving functional roles and participating in long-range tertiary contacts. Yet the self-assembly of these structures has not been well-characterized at the atomic level. With this in mind, the dynamics of nucleic acid hairpin formation and disruption have been studied using a novel computational tool: large-scale, parallel, atomistic molecular dynamics simulation employing an inhomogeneous distributed computer consisting of more than 40,000 processors. Using multiple methodologies, over 500 micro s of atomistic simulation time has been collected for a large ensemble of hairpins (sequence 5'-GGGC[GCAA]GCCU-3'), allowing characterization of rare events not previously observable in simulation. From uncoupled ensemble dynamics simulations in unperturbed folding conditions, we report on 1), competing pathways between the folded and unfolded regions of the conformational space; 2), observed nonnative stacking and basepairing traps; and 3), a helix unwinding-rewinding mode that is differentiated from the unfolding and folding dynamics. A heterogeneous transition state ensemble is characterized structurally through calculations of conformer-specific folding probabilities and a multiplexed replica exchange stochastic dynamics algorithm is used to derive an approximate folding landscape. A comparison between the observed folding mechanism and that of a peptide beta-hairpin analog suggests that although native topology defines the character of the folding landscape, the statistical weighting of potential folding pathways is determined by the chemical nature of the polymer.

Computer Simulation↗
PubMed2004

A methodology for modular representation of guidelines.

Computer-based clinical practice guidelines often need to be modified when medical knowledge evolves or when guidelines are implemented in a local setting with specific constraints and preferences. To enable easy modifications to guidelines and maintain their integrity, we have developed a methodology for modular representation of guidelines. Using this approach, we create guidelines in a hierarchical and modular manner. We use the Axiomatic Design methodology to facilitate the development of independent modules. Design matrices capture the interactions among modules. The design matrices can be used during guideline modification to create a change process and to enable identification of other modules that are affected by a change to a module. We implemented this modular knowledge representation approach by incorporating it into the Guideline Interchange Format (GLIF) language. We applied this approach to encode parts of three outdated guidelines released during 2000-2001, and we revised these designs to model updated releases of the guideline. Qualitative and quantitative metrics were developed to assess the types of changes made to the encoded guidelines.

Adult↗
PubMed1980

Computer-assisted reporting system for the follow-up patients with cardiac pacemakers.

The implantation of large numbers of permanent cardiac pacemakers carries with it the responsibility for continual reassessment of all aspects of patient management. Experience with more than 4,000 pacemaker implants and replacements since 1963 has led to the development of a comprehensive computer-assisted data collection, management, and reporting system for the follow-up of patients with cardiac pacemakers. Over a seven-year period, data forms have been developed for the detailed documentation of pre-operative, intraoperative and follow-up information. These were designed in the form of checklists suitable for direct computer entry using mark-sense document readers. Special emphasis has been placed on pre-operative indications, selection of appropriate pacing systems, reliable follow-up methodology, and monitoring the performance of various pulse-generators. This system makes possible the rapid computer production of hospital records and reports to involved physicians and can be used to schedule follow-up assessments as required. The information also can be used for hospital statistics, billing, research, and pacemaker registration at the provincial, state of federal level. Experience has shown that a computer-assisted methodology is the only practical means of providing adequate follow-up for a large group of patients. In addition, direct access to relevant information helps to create an environment in which essential research can be carried out in the face of demanding clinical practice.

Computers↗
PubMed2002

Human performance cognitive-behavioral modeling: a benefit for occupational safety.

Human Performance Modeling (HPM) is a computer-aided job analysis software methodology used to generate predictions of complex human-automation integration and system flow patterns with the goal of improving operator and system safety. The use of HPM tools has recently been increasing due to reductions in computational cost, augmentations in the tools' fidelity, and usefulness in the generated output. An examination of an Air Man-machine Integration Design and Analysis System (Air MIDAS) model evaluating complex human-automation integration currently underway at NASA Ames Research Center will highlight the importance to occupational safety of considering both cognitive and physical aspects of performance when researching human error.

Computer Simulation↗