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Arm Injuries↗
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Mobile peer-to-grid architecture for paramedical emergency operations.
In this paper we describe a distributed architecture that could be used to link emergency medical centres, hospitals, telephone operators, and ambulances into a hybrid Peer-to-Peer (P2P) and Grid system for the sharing of information and transport of data. Distributed computing techniques can be used to connect static and mobile systems, bringing the different tools, expertise and databases together to aggregate patient data "on-the-fly" and then integrate it into a situation and context-specific patient-centred virtual environment. The scenario presented in this paper encapsulates connecting mobile tools and medical devices from ambulances, enabling data transfer to medical centres, and aggregating patient data from numerous sources. The proposed P2G (Peer-to-Grid) framework consolidates Peer-to-Peer and Grid computing research by addressing the mobility of transiently connected devices while supporting interactive configurability of components for dynamic data-driven distributed paramedical scenarios.
Allied Health Personnel↗
An inventory of computer resources for the medical application of virtual reality.
Within the framework of the scientific community, we could define virtual reality (VR) as an effective simulation of complex environmental aspects related to both interaction-dependent and high-risk operations, where mistakes will lead to unacceptable consequences. Surgeons performing open surgery, endoscopists working on the intestine or neurologists working on the brain-all are impressive examples where the VR approach looks potentially quite interesting. In fact the risk of unsatisfactory implementations, too poor with respect to the complexity of the real world, coming from the unsatisfactory performance of the present-day technology, is quite high. Typically, the loss of the real time requirement for the operator interactions can remove much of the effectiveness of what has been built. Some questions about the real need for high performance computational resources and high level graphic resolution need to be answered. This paper presents and discusses an inventory of computational resources used in real applications.
CD-ROM↗
Rectification for cone-beam projection and backprojection.
The purpose of this paper is to derive a technique for accelerating the computation of cone-beam forward and backward projections that are the basic steps of tomographic reconstruction. The cone-beam geometry of C-arm systems is commonly described with projection matrices. Such matrices provide a continuous framework for analyzing the flow of operations needed to compute backprojection for analytical reconstruction, as well as the combination of forward and backward projections for iterative reconstruction. The proposed rectification technique resampies the original data to planes that are aligned with two of the reconstructed volume main axes, so that the original cone-beam geometry can be replaced by a simpler geometry, where succession of plane magnifications are involved only. Rectification generalizes previous independent results to the cone-beam backprojection of preprocessed data as well as to cone-beam iterative reconstruction. The memory access pattern of simple magnifications provides superior predictability and is, therefore, easier to optimize, independently of the choice of the interpolation technique. Rectification is also shown to provide control over interpolation errors through oversampling, allowing tradeoffs between computation speed and precision to be set. Experimental results are provided for linear and nearest neighbor interpolations, based on simulations, as well as phantom and patient data acquired on a digital C-arm system.
Algorithms↗
[Design and experimental study of computer-assisted orthopaedic system for distal locking of intramedullary nails].
OBJECTIVE: To test the safety and accuracy of the computer-assisted orthopaedic system for distal locking of intramedullary nails and apply it to internal fixation with intramedullary nails in the lower limb. METHODS: According to the theory of mechanical arms stereotactic localization in computer-assisted orthopaedic surgery (CAOS), we design a CAOS system for distal locking of intramedullary nails. The system comprised 2 independent modules: computer-assisted imaging and registration workstation; mechanical stereotactic framework. Ten plastic tibia models, 20 plastic femur models (Synbone AG, Malans, Switzerland) and 6 human cadaver lower limbs were randomly divided into 2 groups undergoing internal fixation with intramedullary nails (Orthofix, Germany). The first group (CAOS group with 5 plastic tibia models, 10 plastic femur models, 6 human cadaver tibia, 6 human cadaver femur; each nail had 2 holes, and 2 distal locking screws were inserted in each bone, which gave a total number of 54 holes) used a computer-assisted orthopaedic system, the second group (CONTROL GROUP is the same as CAOS group) used Orthofix mechanical targeting device for distal locking. Comparison between 2 groups was made in radiation exposure time, operating time, percentage of correctly placed screws. RESULTS: CAOS group: operating time was (4.44 +/- 2.99) min; radiation exposure time was (1.16 +/- 0.38) min; correctly placed screws rate was (100 +/- 0)%. CONTROL GROUP: operating time was (10.42 +/- 4.18) min; radiation exposure time was (4.71 +/- 3.86) min; correctly placed screws rate was (94.44 +/- 0.36)%. Operating time and radiation exposure time in CAOS group were significantly shorter than those in control group (P < 0.05), no differences were found between 2 groups in relation to the percentage of correctly placed screws. CONCLUSIONS: By using CAOS system for distal locking of intramedullary nails, the locking holes can be drilled accurately and safely. Radiation exposure significantly reduced.
Cadaver↗
Policy analysis using patient flow simulations: conceptual framework and study design.
How do we know that innovations in healthcare delivery would work? In this paper, we discuss the idea of applying the methodology of group-randomized intervention studies to evaluation of surgical care policies using data from simulation experiments. We argue that a new interdisciplinary framework, which links health services research, operations research, and computer sciences, is required. Specifically, the methodological rigor of evaluative studies should be applied to the analysis of simulation experiments. In turn, the evaluation of policy initiatives should include the simulation of health-system operations. We introduce the framework and study design to evaluate methods for improving the peri-operative process with the use of patient flow simulations.
Adult↗
Using computed muscle control to generate forward dynamic simulations of human walking from experimental data.
The objective of this study was to develop an efficient methodology for generating muscle-actuated simulations of human walking that closely reproduce experimental measures of kinematics and ground reaction forces. We first introduce a residual elimination algorithm (REA) to compute pelvis and low back kinematic trajectories that ensure consistency between whole-body dynamics and measured ground reactions. We then use a computed muscle control (CMC) algorithm to vary muscle excitations to track experimental joint kinematics within a forward dynamic simulation. CMC explicitly accounts for delays in muscle force production resulting from activation and contraction dynamics while using a general static optimization framework to resolve muscle redundancy. CMC was used to compute muscle excitation patterns that drove a 21-degrees-of-freedom, 92 muscle model to track experimental gait data of 10 healthy young adults. Simulated joint kinematics closely tracked experimental quantities (mean root-mean-squared errors generally less than 1 degrees), and the time histories of muscle activations were similar to electromyographic recordings. A simulation of a half-cycle of gait could be generated using approximately 30 min of computer processing time. The speed and accuracy of REA and CMC make it practical to generate subject-specific simulations of gait.
Algorithms↗
Potential of mean force treatment of salt-mediated protein crystallization.
In the initial stages of crystallization of proteins, monomers aggregate rapidly and form nuclei and large fractal clusters, as previously shown by dynamic light scattering experiments (Georgalis, Y., J. Schüler, J. Frank, D. M. Soumpasis, and W. Saenger. 1995. Protein crystallization screening through scattering techniques. Adv. Colloid Interface Sci. 58:57-86). In this communication we initiate an effort to understand the effective interactions controlling charged protein aggregation and crystallization using the potential of mean force (PMF) theory. We compute the PMFs of the system lysozyme-water-NaCl within the framework of the hypernetted chain approximation for a wide range of protein and salt concentrations. We show that the computed effective interactions can rationalize the experimentally observed aggregation behavior of lysozyme under crystallization conditions.
Biophysical Phenomena↗
General surface reconstruction for cone-beam multislice spiral computed tomography.
A new family of cone-beam reconstruction algorithm, the General Surface Reconstruction (GSR), is proposed and formulated in this paper for multislice spiral computed tomography (CT) reconstructions. It provides a general framework to allow the reconstruction of planar or nonplanar surfaces on a set of rebinned short-scan parallel beam projection data. An iterative surface formation method is proposed as an example to show the possibility to form nonplanar reconstruction surfaces to minimize the adverse effect between the collected cone-beam projection data and the reconstruction surfaces. The improvement in accuracy of the nonplanar surfaces over planar surfaces in the two-dimensional approximate cone-beam reconstructions is mathematically proved and demonstrated using numerical simulations. The proposed GSR algorithm is evaluated by the computer simulation of cone-beam spiral scanning geometry and various mathematical phantoms. The results demonstrate that the GSR algorithm generates much better image quality compared to conventional multislice reconstruction algorithms. For a table speed up to 100 mm per rotation, GSR demonstrates good image quality for both the low-contrast ball phantom and thorax phantom. All other performance parameters are comparable to the single-slice 180 degrees LI (linear interpolation) algorithm, which is considered the "gold standard." GSR also achieves high computing efficiency and good temporal resolution, making it an attractive alternative for the reconstruction of next generation multislice spiral CT data.
Algorithms↗
Toward automatic computer aided dental X-ray analysis using level set method.
A Computer Aided Dental X-rays Analysis (CADXA) framework is proposed to semi-automatically detect areas of bone loss and root decay in digital dental X-rays. In this framework, first, a new proposed competitive coupled level set method is proposed to segment the image into three pathologically meaningful regions using two coupled level set functions. Tailored for the dental clinical environment, the segmentation stage uses a trained support vector machine (SVM) classifier to provide initial contours. Then, based on the segmentation results, an analysis scheme is applied. First, the scheme builds an uncertainty map from which those areas with bone loss will be automatically detected. Secondly, the scheme employs a method based on the SVM and the average intensity profile to isolate the teeth and detect root decay. Experimental results show that our proposed framework is able to automatically detect the areas of bone loss and, when given the orientation of the teeth, it is able to automatically detect the root decay with a seriousness level marked for diagnosis.
Algorithms↗
Bringing metabolic networks to life: integration of kinetic, metabolic, and proteomic data.
BACKGROUND: Translating a known metabolic network into a dynamic model requires reasonable guesses of all enzyme parameters. In Bayesian parameter estimation, model parameters are described by a posterior probability distribution, which scores the potential parameter sets, showing how well each of them agrees with the data and with the prior assumptions made. RESULTS: We compute posterior distributions of kinetic parameters within a Bayesian framework, based on integration of kinetic, thermodynamic, metabolic, and proteomic data. The structure of the metabolic system (i.e., stoichiometries and enzyme regulation) needs to be known, and the reactions are modelled by convenience kinetics with thermodynamically independent parameters. The parameter posterior is computed in two separate steps: a first posterior summarises the available data on enzyme kinetic parameters; an improved second posterior is obtained by integrating metabolic fluxes, concentrations, and enzyme concentrations for one or more steady states. The data can be heterogeneous, incomplete, and uncertain, and the posterior is approximated by a multivariate log-normal distribution. We apply the method to a model of the threonine synthesis pathway: the integration of metabolic data has little effect on the marginal posterior distributions of individual model parameters. Nevertheless, it leads to strong correlations between the parameters in the joint posterior distribution, which greatly improve the model predictions by the following Monte-Carlo simulations. CONCLUSION: We present a standardised method to translate metabolic networks into dynamic models. To determine the model parameters, evidence from various experimental data is combined and weighted using Bayesian parameter estimation. The resulting posterior parameter distribution describes a statistical ensemble of parameter sets; the parameter variances and correlations can account for missing knowledge, measurement uncertainties, or biological variability. The posterior distribution can be used to sample model instances and to obtain probabilistic statements about the model's dynamic behaviour.
Bayes Theorem↗
Physical basis of charge pairing in mitochondria.
The postulate of charge pairing in the mitochondrial inner membrane is justified by applying a formula due to Fuoss to calculate the probability density for the distance between a positive and a negative charge. For dielectric constants 10 or less pairing is absolute, for 20 there is some tendency towards pairing, and at 78 it is nonexistent. Pairing, partner exchange or charge substitution, inhibition, and antiport uncoupling can be rationalized within this framework.
Computers↗
Modern methods of investigation in speech production.
Methodologies of speech research with respect to the production processes are discussed, with an emphasis on the recent development of new instrumental techniques. It is argued that systematic studies of large amounts of speech data are necessary to understand the basic characteristics of speech. The traditional notion of phoneme-size segments seems inappropriate for interpreting multidimensional articulatory movements by a concatenative model. Experimental means such as a computer-controlled X-ray microbeam technique and advanced statistical processing, in combination with a new theoritical framework of phonetic description, promise future development.
Computers↗
Modelling biological depth perception in binocular vision: the local disparity estimation.
This paper presents an approach to solving the correspondence problem in binocular vision and to computing the local horizontal disparity map using a biologically inspired algorithm. A computer application was developed as a tool for implementing, developing, and testing computational models for stereopsis, and also as a framework for integrating the disparity map with other perspective clues. Two models for stereopsis have been implemented. One of them is biologically inspired (it models the behaviour of simple and complex cells from the striate cortex) and the other is the 'classical' model of David Marr and Tomaso Poggio, implemented in order to have a comparison term for the simulation results. The paper details the results obtained on random-dot stereograms and on pairs of real images.
Algorithms↗
AVID: an integrative framework for discovering functional relationships among proteins.
BACKGROUND: Determining the functions of uncharacterized proteins is one of the most pressing problems in the post-genomic era. Large scale protein-protein interaction assays, global mRNA expression analyses and systematic protein localization studies provide experimental information that can be used for this purpose. The data from such experiments contain many false positives and false negatives, but can be processed using computational methods to provide reliable information about protein-protein relationships and protein function. An outstanding and important goal is to predict detailed functional annotation for all uncharacterized proteins that is reliable enough to effectively guide experiments. RESULTS: We present AVID, a computational method that uses a multi-stage learning framework to integrate experimental results with sequence information, generating networks reflecting functional similarities among proteins. We illustrate use of the networks by making predictions of detailed Gene Ontology (GO) annotations in three categories: molecular function, biological process, and cellular component. Applied to the yeast Saccharomyces cerevisiae, AVID provides 37,451 pair-wise functional linkages between 4,191 proteins. These relationships are approximately 65-78% accurate, as assessed by cross-validation testing. Assignments of highly detailed functional descriptors to proteins, based on the networks, are estimated to be approximately 67% accurate for GO categories describing molecular function and cellular component and approximately 52% accurate for terms describing biological process. The predictions cover 1,490 proteins with no previous annotation in GO and also assign more detailed functions to many proteins annotated only with less descriptive terms. Predictions made by AVID are largely distinct from those made by other methods. Out of 37,451 predicted pair-wise relationships, the greatest number shared in common with another method is 3,413. CONCLUSION: AVID provides three networks reflecting functional associations among proteins. We use these networks to generate new, highly detailed functional predictions for roughly half of the yeast proteome that are reliable enough to drive targeted experimental investigations. The predictions suggest many specific, testable hypotheses. All of the data are available as downloadable files as well as through an interactive website at http://web.mit.edu/biology/keating/AVID. Thus, AVID will be a valuable resource for experimental biologists.
Algorithms↗
Virtual shelves in a digital library: a framework for access to networked information sources.
OBJECTIVE: Develop a framework for collections-based access to networked information sources that addresses the problem of location-dependent access to information sources. DESIGN: This framework uses a metaphor of a virtual shelf. A virtual shelf is a general-purpose server that is dedicated to a particular information subject class. The identifier of one of these servers identifies its subject class. Location-independent call numbers are assigned to information sources. Call numbers are based on standard vocabulary codes. The call numbers are first mapped to the location-independent identifiers of virtual shelves. When access to an information resource is required, a location directory provides a second mapping of these location-independent server identifiers to actual network locations. RESULTS: The framework has been implemented in two different systems. One system is based on the Open System Foundation/Distributed Computing Environment and the other is based on the World Wide Web. CONCLUSIONS: This framework applies in new ways traditional methods of library classification and cataloging. It is compatible with two traditional styles of selecting information searching and browsing. Traditional methods may be combined with new paradigms of information searching that will be able to take advantage of the special properties of digital information. Cooperation between the library-informational science community and the informatics community can provide a means for a continuing application of the knowledge and techniques of library science to the new problems of networked information sources.
Catalogs, Library↗
Decision analysis: a framework for critical care decision assistance.
The ultimate goal of medical computer systems is to help clinicians make good decisions. Such systems must be based on sound principles. Decision analysis is a 25-year-old discipline that provides the needed rigorous foundation for decision assistance. Decision analysis comprises the philosophy, procedures, and tools that can correct the flaws in existing critical care decision-making practice. Intelligent decision systems--computer-based systems that automate decision analysis--make it practical to apply decision analysis to critical care. Orchestra is a pilot intelligent decision system (now under development) that coordinates the efforts of the critical care specialist, the bedside physician, and the bedside nurse in building decision models that can provide recommendations and insight for ventilator management decisions. Decision analysis delivered by intelligent decision systems has great potential for improving critical care decision-making.
Algorithms↗
Randomized trial of geragogy-based medication instruction in the emergency department.
BACKGROUND: Medication adherence by older adults who are discharged from the emergency department (ED) is an essential attribute of effective treatment. Researchers have demonstrated that delivery of well-structured instructions increases the knowledge of discharge regimens and increases adherence among ED populations. OBJECTIVES: This study compared the level of medication knowledge of elderly ED patients receiving instruction by one of two teaching methods: the usual preprinted discharge instructions with handwritten medication information and individualized computer-generated discharge instructions designed within a geragogy framework. METHOD: The geragogy intervention included large-print, easily readable, specific information ordered within the elderly memory schema. This schema consists of purpose, administration, and emergency information in that order. The Knowledge of Medication Subtest by Horn and Swain (1977) was administered by telephone 48 to 72 hours after discharge. Sixty patients (38 women, 22 men) with a mean age of 76 years were randomly assigned to groups and completed the study at three rural ED sites. RESULTS: Subjects in the geragogy-based intervention group demonstrated significantly more knowledge of medications than did subjects experiencing the usual discharge teaching method (t = 2.19, p = .016). CONCLUSIONS: These findings suggest that a medication teaching intervention geared to the special needs of the elderly can be effective in increasing medication knowledge.
Aged↗