PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “computational frameworks”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 307 records · Page 17Linked to original sources

Farmer health beliefs about an occupational illness that affects farmworkers: the case of green tobacco sickness.

Latino migrant and seasonal farmworkers, like all agricultural workers, experience high rates of occupational illness and injury. Interventions to reduce occupational injury among farmworkers must attend to the health beliefs of agricultural employers as well as employees, as employers control many aspects of the work environment. Occupational safety programs for Latino migrant and seasonal farmworkers must also be conceptually based in health behavior change and health disparities theories. We examine health beliefs of tobacco farmers about green tobacco sickness (GTS) to show the importance of delineating employer beliefs in agricultural safety. GTS is a highly prevalent occupational illness among tobacco workers that results from nicotine poisoning through dermal absorption of nicotine during cultivation and harvesting. We use qualitative methods structured by the Explanatory Models of Illness approach to identify farmer beliefs about the etiology, onset, pathophysiology, course, and treatment of GTS. Data were collected through semi-structured in-depth interviews with 15 North Carolina tobacco farmers. A computer-assisted, systematic qualitative analysis framework was applied to the interview transcripts. While tobacco farmers were generally knowledgeable about GTS, their explanatory models for this occupational illness often mis-identified its causes (heat and bending rather than nicotine) and minimized its seriousness. These models included methods of prevention that are not proven (e.g., use of anti-nausea drugs) or are more harmful than GTS (smoking cigarettes). The need for medical treatment was also discounted. Addressing each of these beliefs is important in any program to prevent GTS among farmworkers. Documenting and understanding the beliefs and knowledge of agricultural employers is an important undertaking in our efforts to reduce occupational injury and illness among farmworkers.

Adult↗

Ecological interface design: progress and challenges.

Ecological interface design (EID) is a theoretical framework for designing human-computer interfaces for complex sociotechnical systems. Its primary aim is to support knowledge workers in adapting to change and novelty. This literature review shows that in situations requiring problem solving, EID improves performance when compared with current design approaches in industry. EID has been applied to industry-scale problems in a broad variety of application domains (e.g., process control, aviation, computer network management, software engineering, medicine, command and control, and information retrieval) and has consistently led to the identification of new information requirements. An experimental evaluation of EID using a full-fidelity simulator with professional workers has yet to be conducted, although some are planned. Several significant challenges remain as obstacles to the confident use of EID in industry. Promising paths for addressing these outstanding issues are identified. Actual or potential applications of this research include improving the safety and productivity of complex sociotechnical systems.

Data Display↗

Virtual training simulator--designer of EEG signals for tutoring students and doctors to methods of quantitative EEG analysis (qEEG).

Within the framework of the system for computer diagnostics of EEG (qEEG) NeuroResearcher 5.2 is created virtual training simulator--designer of EEG signals and models multidimensional neurodynamic systems of the brain. It is intended for tutoring with minimum engaging of mathematical formulas of doctors and students to comprehension of essence of mathematical methods (classical correlation and spectral analysis and newest methods of multi-dimensional analysis of neurodynamic systems of the brain), which are successfully used for quantitative EEG (qEEG).

Computer Simulation↗

Characterizing the use of health care services delivered via computer networks.

OBJECTIVE: Evaluators must develop methods to characterize the use of the rapidly proliferating electronic networks that link patients with health services. In this article the 4-S framework is proposed for characterizing the use of health services delivered via computer networks. The utility of the 4-S framework is illustrated using data derived from a completed, randomized field experiment in which 47 caregivers of persons who had Alzheimer's disease accessed ComputerLink, a special computer network providing information, communication, and decision support to homebound caregivers of persons who have Alzheimer's disease. DESIGN: Human-computer interaction theories characterize the use of health services delivered via computer networks in behavioral terms. The 4-S framework incorporates perspectives based on user (subject) behavior: access to and use of the total system, use of specific services, behavior within single sessions, and enduring behavioral characteristics. The 4-S framework was tested in a secondary analysis of data from over 3,800 uses of ComputerLink. MEASUREMENT: The 4-S framework was instantiated using data obtained from the ComputerLink evaluation. Three types of secondary data were obtained. A passive monitor of access to the computer network provided quantitative information, such as time of day when access occurred, duration of access, and sequence of services used. Full-text messages were available from the public message postings. Subjective appraisal of use was obtained from self-reporting by users at the end of the experiment. RESULTS: The components of the 4-S framework were suitable to characterize operational aspects of ComputerLink use by Alzheimer's disease caregivers. Through application of the 4-S framework, an understanding of both quantitative use and qualitative use emerged (e.g., insight was gained into the differential use of specific services). CONCLUSIONS: The 4-S framework provided a mechanism for combining various measures of use into a coherent whole. The framework promotes a precise characterization of use and thereby facilitates evaluation of health services delivered via computer networks. It is suitable for evaluation of user satisfaction, measurement of needs resolution, and ascertainment of selected clinical outcomes.

Alzheimer Disease↗

[Effect of the computer-assisted diagnostic system [ADM] on the success and cost of diagnosis (author's transl)].

Taking into account the interest we have in helping physicians arrive at a diagnosis and in choosing the procedures utilized in the computer-assisted diagnostic system (ADM) already described, a study was devised to estimate the efficiency of the system in relation to costs. From 300 patient records, 80 presenting a true diagnostic problem within the framework of the diseases already in computer memory were selected. A comparison was made between the normal procedure, with and without computer help, keeping in mind the diagnoses themselves as well as the performance and the cost. Criteria and evaluation methods were evaluated. The results, even though preliminary, are encouraging and justify the continued development of the system.

Cost-Benefit Analysis↗

A computational model for shape from texture.

Shape from texture is best analysed in a two-stage framework analogous to stereopsis and structure from motion: (a) computing the 'texture distortion' from the image; and (b) interpreting the 'texture distortion' to infer the orientation and shape of the scene surface in 3D. We model the texture distortion at a point in any particular direction on the image plane as an affine transformation and derive the relationship between the parameters of the affine transformation and the surface shape and orientation. We have developed a technique for estimating affine transforms between nearby image patches which is based on solving a system of linear constraints derived from a differential analysis. It is not necessary explicitly to identify texels or make restrictive assumptions about the nature of the image texture like isotropy. We have developed two different models for recovering surface orientation (slant and tilt) and shape (principal curvatures and directions) based on the estimated affine transforms in a number of directions. Experimental results are presented on images of planar and curved surfaces under perspective projection.

Animals↗

A computational basis to object?

To use an object, we must be able to perceive the spatial relationship between the object's parts. The accepted view of how the brain coherently encodes an object is that some neurons in the frontal cortex employ an object-centered coordinate frame. A new computational model challenges this view, using the rich conceptual framework of neural basis functions.

Computational Biology↗

Stress distribution on the metal framework of the implant-supported fixed prosthesis using different veneering materials.

PURPOSE: This study evaluated stress distribution in metal frameworks constructed on implants under masticatory forces using computer simulations. MATERIALS AND METHODS: Three-dimensional finite element analysis was used to study four different veneering materials-metal framework combinations using Calcitek implants. The veneering materials used in the study were porcelain, heat-polymerized poly(methyl methacrylate) resin, microfilled composite resin, and glass-modified composite resin. All computations were conducted for different levels on the buccal and lingual sides. RESULTS: Changing the veneering material on the prosthesis produced significant effects on stress levels and stress distribution on the metal frameworks. Stresses were concentrated along the marginal area of the prosthesis. Acrylic resin showed greater displacement than porcelain, probably because of its lower modulus of elasticity. CONCLUSION: In comparison to porcelain, more stress is borne by the acrylic resin-veneered metal framework under static loading.

Acrylic Resins↗

Cost-effective management of high-risk patients: a case-map approach.

BACKGROUND: The case-management approach to patient care used by most cardiac surgical practices frequently highlights patients designated as high-risk. Increased risk might be because of advanced age, the need for complex reoperations, high risk of bleeding, and renal failure, all of which may be superimposed on poor ventricular performance. METHODS: A small consensus panel of cardiac surgeons, anesthesiologists, perfusionists, cardiac-care nurse managers, and coagulation experts met to assess the potential for development of case-management pathways targeted towards high-risk coronary artery bypass graft patients. The process comprised review of the literature to identify risk factors and strategies most cost-effective in reducing risk. RESULTS: A series of management strategies driven by data from the literature--or by consensus when such information was not available--were developed to cost-effectively manage the high-risk patient. The process was then converted to a multidimensional computer program. This personal computer-driven program served as a framework upon which any institution could impose its own practice style and modify recommendations. The program was designed to be interactive and to allow easy transition from patient-management strategies to support data. A facilitator generally coordinates the interaction between the local patient-care group and the computer information base to evolve a case-management map. CONCLUSIONS: By using stored information based on current literature and easily updated, the system is both educational and product oriented, and provides a case-map approach to the cost-effective management of patients during the preoperative, intraoperative, and postoperative phases of hospital care.

Case Management↗

A generalizable framework for information systems for physician recruitment/referral.

Hospital information systems have evolved from data processing systems for patient billing and payroll to decision-support systems which support decision making at the middle and upper management levels. With the advancements in the areas of database management, expert systems and networks, important hospital functions such as physician recruitment and referral which historically were performed using traditional procedures, are now performed using these computer-based technologies. Develops a generalizable framework for information systems for physician recruitment and referral using technologies of database management, expert systems and networks. This GIS-PRR system may be used by hospitals and other health-care providers to improve the efficiency and effectiveness of the physician recruitment/referral process.

Database Management Systems↗

Stereopsis, vertical disparity and relief transformations.

The pattern of retinal binocular disparities acquired by a fixating visual system depends on both the depth structure of the scene and the viewing geometry. This paper treats the problem of interpreting the disparity pattern in terms of scene structure without relying on estimates of fixation position from eye movement control and proprioception mechanisms. We propose a sequential decomposition of this interpretation process into disparity correction, which is used to compute three-dimensional structure up to a relief transformation, and disparity normalization, which is used to resolve the relief ambiguity to obtain metric structure. We point out that the disparity normalization stage can often be omitted, since relief transformations preserve important properties such as depth ordering and coplanarity. Based on this framework we analyse three previously proposed computational models of disparity processing; the Mayhew and Longuet-Higgins model, the deformation model and the polar angle disparity model. We show how these models are related, and argue that none of them can account satisfactorily for available psychophysical data. We therefore propose an alternative model, regional disparity correction. Using this model we derive predictions for a number of experiments based on vertical disparity manipulations, and compare them to available experimental data. The paper is concluded with a summary and a discussion of the possible architectures and mechanisms underling stereopsis in the human visual system.

Convergence, Ocular↗

[Value of computer tomographic determination of spleen size for the elucidation of splenic involvement within the framework of primary lymph node neoplasms].

The splenic index was determined in 155 persons, without evidence of splenic disease, in order to obtain a simple measure of splenic size. Subsequently 36 patients with malignant lymphomas and who then had their spleens removed were examined by CT. A comparison of the CT and pathological-anatomical findings showed that it is a valuable non-invasive method for diagnosing splenic involvement, having a specificity of 86%, sensitivity of 77% and accuracy of 83%.

Adolescent↗

Neuronal-based synaptic compensation: a computational study in Alzheimer's disease.

In the framework of an associative memory model, we study the interplay between synaptic deletion and compensation, and memory deterioration, a clinical hallmark of Alzheimer's disease. Our study is motivated by experimental evidence that there are regulatory mechanisms that take part in the homeostasis of neuronal activity and act on the neuronal level. We show that following synaptic deletion, synaptic compensation can be carried out efficiently by a local, dynamic mechanism, where each neuron maintains the profile of its incoming post-synaptic current. Our results open up the possibility that the primary factor in the pathogenesis of cognitive deficiencies in Alzheimer's disease (AD) is the failure of local neuronal regulatory mechanisms. Allowing for neuronal death, we observe two pathological routes in AD, leading to different correlations between the levels of structural damage and functional decline.

Alzheimer Disease↗

Chimeric and humanized antibodies with specificity for the CD33 antigen.

L and H chain cDNAs of M195, a murine mAb that binds to the CD33 Ag on normal and leukemic myeloid cells, were cloned. The cDNAs were used in the construction of mouse/human IgG1 and IgG3 chimeric antibodies. In addition, humanized antibodies were constructed which combined the complementarity-determining regions of the M195 antibody with human framework and constant regions. The human framework was chosen to maximize homology with the M195 V domain sequence. Moreover, a computer model of M195 was used to identify several framework amino acids that are likely to interact with the complementarity-determining regions, and these residues were also retained in the humanized antibodies. Unexpectedly, the humanized IgG1 and IgG3 M195 antibodies, which have reshaped V regions, have higher apparent binding affinity for the CD33 Ag than the chimeric or mouse antibodies.

Amino Acid Sequence↗

A Bayesian framework for understanding texture segmentation in the primary visual cortex.

This paper presents a mathematical theory for understanding the computations involved in texture segmentation in the primary visual cortex. We propose that texture segmentation is a part of the early visual system's overall strategy to infer surfaces of objects in a visual scene. Based on this insight, we use the Bayesian inference paradigm to formulate the texture segmentation problem into a maximum a posteriori surface inference problem. The dynamical system for finding the optimal solution of this problem can be characterized by two concurrent and interactive processes: a gradual sharpening of the boundary signals and a simultaneous smoothing of the surface signals. The behavior of these dynamical processes was studied using both analytical and computational methods. We present some computational results and mathematical predictions. This theory suggests a novel framework for understanding the functional roles of the complex cells in the primary visual cortex.

Bayes Theorem↗

Inferring the impact of linguistic boundaries on population differentiation: application to the Afro-Asiatic-Indo-European case.

We present here a quantitative way to assess the impact of language-family boundaries on population differentiation and to evaluate the homogeneity of the genetic processes along these boundaries. Our estimator (delta a) of the impact of the boundary is based on an isolation by distance (IBD) model and measures the added genetic distance between populations located on different sides of the boundary. We compare this statistic with another estimator of group differentiation (F(CT)) computed under an analysis of variance framework that does not assume any particular spatial structure of the populations. Monte Carlo simulations are used to study the behaviour of these statistics under a two-dimensional stepping-stone model. Simulations show that F(CT) can suggest the existence of a frontier when populations only differ because of IBD. This spurious behaviour is much less frequent for the delta a statistic. However, the large variance associated with the delta a statistic, and the fact that it should only be computed in the presence of IBD, may limit the use of this statistic. Overall, the origin and the effect of the boundary is best understood by comparing different statistics and by testing for the presence of IBD on each side of the boundary as well as across the boundary. We illustrate our approach by examining the boundary between Afro-Asiatic and Indo-European populations. These populations are globally genetically differentiated, but the effect of the linguistic boundary on gene flow seems geographically very heterogeneous. This boundary appears to be the result of a secondary contact between two differentiation centres rather than an enhancer of population differentiation.

Africa↗

Source-detector calibration in three-dimensional Bayesian optical diffusion tomography.

Optical diffusion tomography is a method for reconstructing three-dimensional optical properties from light that passes through a highly scattering medium. Computing reconstructions from such data requires the solution of a nonlinear inverse problem. The situation is further complicated by the fact that while reconstruction algorithms typically assume exact knowledge of the optical source and detector coupling coefficients, these coupling coefficients are generally not available in practical measurement systems. A new method for estimating these unknown coupling coefficients in the three-dimensional reconstruction process is described. The joint problem of coefficient estimation and three-dimensional reconstruction is formulated in a Bayesian framework, and the resulting estimates are computed by using a variation of iterative coordinate descent optimization that is adapted for this problem. Simulations show that this approach is an accurate and efficient method for simultaneous reconstruction of absorption and diffusion coefficients as well as the coupling coefficients. A simple experimental result validates the approach.

Bayes Theorem↗

Biological computation.

It is argued that biological systems can be viewed as special computing devices. This view emerges from considerations of how information is stored in and retrieved from the genes. Genes can only specify the properties of the proteins they code for, and any integrative properties of the system must be 'computed' by their interactions. This provides a framework for analysis by simulation and sets practical bounds on what can be achieved by reductionist models.

Computational Biology↗