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At least 253 records · Page 14Linked to original sources

PubMedDate not supplied

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↗

PubMedDate not supplied

[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↗

PubMed1994

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↗

PubMedDate not supplied

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↗

PubMed1997

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↗

PubMed1995

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↗

PubMed1995

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↗

PubMed1985

[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↗

PubMed1996

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↗

PubMed1992

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↗

PubMed1995

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↗

PubMed2000

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↗

PubMed1998

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↗

PubMedDate not supplied

Using ICPC in a computer-based primary care information system.

INTRODUCTION: Although the framework of the episode of care offers much promise in examining the process of primary health care, the development of episode-oriented, automated data sources has proceeded slowly. Experience with the International Classification of Primary Care (ICPC) in the European Community has confirmed its usefulness in creating and analyzing episodes of care, but it has seen little use in the United States. We describe the development of a Primary Care Information System (PCIS), which employs ICPC to create episodes of care from routinely collected clinical data. METHODS: The PCIS is a partially computerized medical information system running on a standard Macintosh microcomputer. The PCIS integrates ICPC, ICD-9-CM, and CPT-4 coding structures to provide episode-oriented data for clinical, administrative, research, and reimbursement needs. The performance of the PCIS was assessed based on five major issues: clinician cooperation, data-entry accuracy, validity of episode data, cost, and perceived value to users. RESULTS: The data collection and entry process required minimal additional effort from clinicians and data-entry personnel, and data-entry accuracy exceeded published estimates for other primary care data sources. Data management costs of about $1 per encounter compare favorably to published estimates for other office-based clinical information systems. The major problem seen during pilot testing was inaccurate tracking of episode boundaries through changes in providers and consequent changes in labels for problems and diagnoses. This problem has been addressed in development of the second-generation PCIS. CONCLUSION: The combination of an episode-oriented framework such as ICPC and a flexible medical information system provides a promising platform for the study of the content and process of primary health care.

Family Practice↗

PubMed2001

From paper-based to electronic guidelines: application to French guidelines.

In order to develop an internet-based decision support system, making available for French general practitioners several prevention guidelines is was necessary to implement paper based guideline. We propose a framework allowing to transform paper based practice guideline into their electronic form. Three different problems were identified: computability (e.g. determinism of the eCPG), logic (e.g. ambiguities when combining Booleans operators) and external validity (i.e. stability of decision for variations around thresholds and proportion of subjects classified in the various terminal nodes). The last problem concerned documentation of evidence: the level of evidence was associated only with the terminal decision node and not with the pathway through the decision tree. We concluded that computerisation of guidelines is not possible without expertise or authors advice. To improve computability it is necessary to provide authors with a framework that checks ambiguities, and logical errors.

Algorithms↗

PubMed1996

A comparison of two murine monoclonal antibodies humanized by CDR-grafting and variable domain resurfacing.

The variable domain resurfacing and CDR-grafting approaches to antibody humanization were compared directly on the two murine monoclonal antibodies N901 (anti-CD56) and anti-B4 (anti-CD19). Resurfacing replaces the set of surface residues of a rodent variable region with a human set of surface residues. The method of CDR-grafting conceptually consists of transferring the CDRs from a rodent antibody onto the Fv framework of a human antibody. Computer-aided molecular modeling was used to design the initial CDR-grafted and resurfaced versions of these two antibodies. The initial versions of resurfaced N901 and resurfaced anti-B4 maintained the full binding affinity of the original murine parent antibodies and further refinements to these versions described herein generated five new resurfaced antibodies that contain fewer murine residues at surface positions, four of which also have the full parental binding affinity. A mutational study of three surface positions within 5 A of the CDRs of resurfaced anti-B4 revealed a remarkable ability of the resurfaced antibodies to maintain binding affinity despite dramatic changes of charges near their antigen recognition surfaces, suggesting that the resurfacing approach can be used with a high degree of confidence to design humanized antibodies that maintain the full parental binding affinity. By comparison CDR-grafted anti-B4 antibodies with parental affinity were produced only after seventeen versions were attempted using two different strategies for selecting the human acceptor frameworks. For both the CDR-grafted anti-B4 and N901 antibodies, full restoration of antigen binding affinity was achieved when the most identical human acceptor frameworks were selected. The CDR-grafted anti-B4 antibodies that maintained high affinity binding for CD19 had more murine residues at surface positions than any of the three versions of the resurfaced anti-B4 antibody. This observation suggests that the resurfacing approach can be used to produce humanized antibodies with reduced antigenic potential relative to their corresponding CDR-grafted versions.

Amino Acid Sequence↗

PubMed1985

Computer-based information systems models. Perspectives for nursing.

A synthesis of theories from the management information systems (MIS) field provided the conceptual framework to describe how to design and develop effective computer-based information systems. An analysis of activities and interviews with nurse managers in a tertiary care medical center provided the basis for describing five major nursing department functions and the information requirements arising from those functions. The MIS framework was applied to the nursing department information requirements in order to derive MNIS, a normative model of a nursing information system, which was then used to "bench mark" the current status of commercially available nursing information systems. The researchers compared the MNIS with 28 nursing information systems that vendors are currently developing or marketing. The comparison revealed large gaps between nursing department needs and vendor-provided solutions.

Commerce↗

PubMedDate not supplied

A computer-based AIDS education program for nursing students.

A multidisciplinary team has developed a computer-based software program for educating nursing students and other college students about six sexually transmitted diseases (STDs). The program for educating about Acquired Immune Deficiency Syndrome (AIDS) is the first of the six "Smartbooks" to be completed, using the Hypercard Expert System shell on the Macintosh computer. Information is organized within a framework known as a concept map, and the student user progresses through the program in a self-directed way by "clicking" on the portion of the concept map that is of interest. Thus, the knowledge base can be accessed in many different ways, and is not restricted to a linear format. Comparative quantitative analysis using a control program shows consistently better student retention of information presented within the program that features concept maps. Qualitative results indicate that students find the conceptually-arranged knowledge base implicitly easy to understand, "fun" to use, and interesting to explore. Educational theory suggests that the success of such a format may be related to the schematic nature of memory.

Acquired Immunodeficiency Syndrome↗