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PubMed1985

Spatial location and hyperacuity: flank position within the centre and surround zones.

Sensitivity to a horizontal displacement of a vertical line was measured in order to ascertain the influence of the location of parallel flanking lines on the apparent position of features in visual space. The first experiment confirmed that the introduction of the flank added a component to the apparent shift which was towards the flank for small separations (less than 3-4') and away from the flank with larger separations. The second experiment investigated the notion that apparent location is derived by collecting information only from zones adjacent to the target and limited in the vertical extent by the target's height i.e. information orthogonal to the target's main axis. This was done by placing a vertical flank at a horizontal distance from the target that would be clearly within one zone or the other and measuring the effect of a vertical separation between the two flank halves. In the surround zone the amount of repulsion obtained was not influenced by vertical separation of the flank halves, even when they were several minutes higher (or lower) than the target line. In the central zone attraction was only obtained when the vertical separation was small enough to provide some overlap of the lines in the horizontal direction. With larger separations substantial repulsion was obtained. We conclude that while the central 'attraction' zone may only use information distributed in the direction of the line's displacement, it does so only within a 3-4' range on either side of the target line. The surround zone is not similarly limited in the region over which it collects information to influence the apparent location of features.

Humans↗
PubMed2006

Grid technology in tissue-based diagnosis: fundamentals and potential developments.

Tissue-based diagnosis still remains the most reliable and specific diagnostic medical procedure. It is involved in all technological developments in medicine and biology and incorporates tools of quite different applications. These range from molecular genetics to image acquisition and recognition algorithms (for image analysis), or from tissue culture to electronic communication services. Grid technology seems to possess all features to efficiently target specific constellations of an individual patient in order to obtain a detailed and accurate diagnosis in providing all relevant information and references. Grid technology can be briefly explained by so-called nodes that are linked together and share certain communication rules in using open standards. The number of nodes can vary as well as their functionality, depending on the needs of a specific user at a given point in time. In the beginning of grid technology, the nodes were used as supercomputers in combining and enhancing the computation power. At present, at least five different Grid functions can be distinguished, that comprise 1) computation services, 2) data services, 3) application services, 4) information services, and 5) knowledge services. The general structures and functions of a Grid are described, and their potential implementation into virtual tissue-based diagnosis is analyzed. As a result Grid technology offers a new dimension to access distributed information and knowledge and to improving the quality in tissue-based diagnosis and therefore improving the medical quality.

Journal Article↗
PubMed1997

MedWeaver: integrating decision support, literature searching, and Web exploration using the UMLS Metathesaurus.

Integrating functions from disparate and widely-distributed information systems has been an interest of the medical informatics community for some time. Barriers to progress have included the lack of network-accessible information sources, inadequate methods for inter-system messaging, and lack of vocabulary translation services. With the advent of the World Wide Web (WWW) and the evolution of the National Library of Medicine's Unified Medical Language System (UMLS), it is now possible to develop applications that integrate functions from diverse, distributed systems. In this paper we describe one such system, MedWeaver, a WWW application that integrates functions from a decision support application (DXplain), a literature searching system (WebMedline), and a clinical Web searching system (CliniWeb) using the UMLS Metathesaurus for vocabulary translation. This system demonstrates how application developers can design systems around anticipated clinical information needs and then draw together the needed content and functionality from diverse sources.

Computer Communication Networks↗
PubMed2000

Epidemiological study of 134 subjects with allergic conjunctivitis.

At times it is difficult to distinguish among the subtypes of chronic allergic conjunctivitis. A prospective study with 134 patients was carried out. Patients were diagnosed with vernal keratoconjunctivitis (VKC), atopic keratoconjunctivitis (AKC) or perennial allergic conjunctivitis (PAC). Demographic information was also collected including, age at symptom onset, sex, history of non-ocular allergy, and history of family allergy. Forty-six percent were diagnosed with VKC, 40% with AKC, 8% with PAC, and 6% were not specifically diagnosed. This distribution information as well as the demographic information collected demonstrates that there are patterns within each subgroup of chronic ocular allergy sufferers. These findings will be helpful in the diagnosing and proper classification of ocular allergic conditions.

Brazil↗
PubMedDate not supplied

A framework for the integration of distributed autonomous healthcare information systems.

This paper presents a domain-specific framework for the integration of geographically distributed heterogeneous autonomous healthcare information systems. Integration is seen and understood in terms of access to information resources, and in terms of content, structure, and visualization of patient record segments, with the goal of creating a virtual patient record at the medical workstations. The proposed approach covers integration aspects related to presentation, control, data, and function. The architecture and the components of the framework are based on the newly introduced Patient Meta-Record (PMR) concept, but also make use of existing or emerging standards for distributed object-oriented computing and information presentation. At the application and middle-ware layers of the presented healthcare information systems architecture, the PMR concept enhances or enables services for data mediation, distributed directory access, and workflow management. At the bitways layer, high performance networks provide a fast medium, which is indispensable for medical image distribution, collaborative work, hypermedia library applications, and teleconsultation.

Computer Communication Networks↗
PubMed2000

Informed decisions by clinicians are fundamental for EPR implementation.

Most often the investment in electronic patient records (EPR) is decided upon on the basis of descriptions of all the advantages this new technology will bring. We argue that an exchange of a paper-based patient record (PPR) with an EPR is an efficient way to automate manual routine work and distribute information but the real benefits from EPR depend on how clinicians use an EPR application to improve the quality of care. We introduce the 'price to pay' concept in order to illustrate that it takes a human effort to create better health care and that clinicians therefore play a very important role when implementing EPR systems.

Computer Literacy↗
PubMed1989

Conceptual model for the use of aerial color infrared photography by mosquito control districts as a survey technique for Psorophora columbiae oviposition habitats in Texas ricelands.

Two photographic missions per year are recommended to provide information on land-use and mosquito oviposition habitats. A winter mission, following a rain, will-provide a view of low areas within fields which may be obscured by summer vegetation. A summer mission will provide current land-use and crop distribution information and may show plant stress conditions due to excessive soil moisture. An aerial color infrared photographic survey with directed ground verification should result in a substantial savings in cost and increased efficiency in surveillance of mosquito producing habitats over ground survey techniques currently employed by mosquito control districts.

Animals↗
PubMedDate not supplied

Ensuring health care quality: a purchaser's perspective--a health care coalition.

This paper explores how one health care purchasing coalition in Minnesota, the Buyers Health Care Action Group (BHCAG), has taken an active role in restructuring its local health care market. BHCAG started with the belief that the consumer should be the motivating force in health care delivery. Unfortunately, providing consumers with the information and incentives they need to make informed, effective health care decisions has triggered numerous problems. This paper examines groups of providers who network to form care systems, and explores the roles of consumers, employers, and health plans in the current market. It identifies specific methods for gathering data and distributing information to the consumer, and discusses the problems associated with attempting to implement quality improvement, as well as the questions that arise when the market does not support those improvements.

Health Care Coalitions↗
PubMed1998

[Use of Intranet in the hospital setting].

In the Intranet system, the organization uses technologies developed and applied in the Internet network world-wide. Hospitals can use Internet technologies to make hospital information systems more efficient by improving use of existing systems and by adding additional possibilities. Furthermore, the hospital can improve its relations with its customers and also bring the organization additional customers. Intranet implementation can be divided into the areas of: communication, managing and distributing information, and application linkage. Implementation must be modular, gradual and planned according to economic, technological and organizational aspects of the hospitals. By the Intranet, organizations can achieve benefits that include: improving communication array, availability of data and information, using existing information systems and their applications, enhancing customer satisfaction and saving costs of manual application systems.

Hospital Information Systems↗
PubMed1986

Data storage and retrieval.

The entire face of modern medical and surgical practice is being significantly affected by the application of technologic developments to the practice of surgery--developments that will tie together such areas as information management and processing, robotics, communication networks, and computerized surgical equipment. The achievements in these areas will create a sophisticated, fully automatic system that will assist the plastic surgeon in many aspects of work, such as regular office activities, doctor-patient interaction, professional updating, communication, and even assistance during the operational process itself. It will be as simple as dialing a telephone today. When it is necessary to consult with other colleagues, a combined vocal and visual consulting network in other medical centers as well as consulting computerized expert systems will be available all day and night as part of the communication services. The plastic surgical expert systems will store valuable information, based on the knowledge of the best human experts, on any important subtopics and will be accessed in a very friendly way. This will be an invaluable tool for the residents in training, for emergency room work, and for just getting a second opinion, even for the more experienced practitioner. All the electronic mail, professional magazines, and any other required professional information will flow between central and personal retrieval systems. The doctor, at a desired time in the privacy and comfort of his or her own home or office, can read the mail, make required changes to suit his or her needs, and store, send back, or distribute information, all in a speedy and efficient manner. The simulation of a planned surgery will give the surgeon the ability to prepare and will prevent difficulties during complicated procedures through the luxury of a dry run, without any sequelae if certain expected outcomes fail to materialize. The preprogrammed control of sophisticated surgical equipment and the use of robotics would generate new operational possibilities for more complicated surgeries, which are now prevented owing to the surgeon's physical limitations. Information urgently required during the operation as a result of an unexpected situation will be available immediately from storage and retrieval systems, and real-time vocal and visual consulting with expert colleagues, often in remote locations, will bring the operations process itself to a new era.(ABSTRACT TRUNCATED AT 400 WORDS)

Artificial Intelligence↗
PubMed1995

Comparison of patients' needs for information on prostate surgery with printed materials provided by surgeons.

OBJECTIVES: To identify strengths, weaknesses, and omissions in existing leaflets and factsheets on prostatectomy given by surgeons to patients. DESIGN: Comparison of content of leaflets and factsheets with patients' needs and discontents in a questionnaire survey as part of the national prostatectomy audit. SETTING: All NHS and independent hospitals performing prostatectomy in four health regions. SUBJECTS: 87 surgeons, 53 of whom used printed material to inform patients about their operations; a total of 25 different factsheets being used. 5361 men undergoing prostatectomy were sent a closed response questionnaire about their treatment; 4226 men returned it completed. A random sample of 2000 patients was asked for further comments, of whom 807 supplied pertinent comments. MAIN MEASURES: Content of the 25 factsheets compared with patients' needs identified in the questionnaires. RESULTS: Much of the information distributed had considerable shortcomings: it lacked uniformity in form and content, topics of relevance to patients were omitted, terminology was often poor, and patients' experience was at variance with what their surgeons said. For example, only one factsheet discussed the potential consequences of malignancy. Patients wanted more information on prostate cancer (1250(29%)) and some thought that the explanation of biopsy results was inadequate (29(4%)). Only six factsheets discussed the possible changes in sexual sensation after transurethral resection of the prostate, stating that patients would feel no change. However, 1490(35%) patients reported a change and 500(12%) were worried about it. CONCLUSION: Current standards of printed information do not meet the needs and requirements of patients undergoing prostatectomy.

General Surgery↗
PubMed1997

An ontology-based multi-agent architecture for distributed health-care information systems.

Managing patients in a shared-care context is a knowledge-intensive activity. To support cooperative work in medical care, computer technology should both augment the capabilities of individual specialists and enhance their ability of interacting with each other and with computational resources. Thus, a major shift is needed from centralized first generation health-care information systems to distributed environments composed of several interconnected agents, cooperating in maintaining a full track of the patient clinical history and supporting health-care providers in all the phases of the patient-management process. This paper outlines a general methodology to make architectural choices while designing or integrating new software components into a distributed health-care information system. A particular stress is laid on the specification of shared conceptual models, or ontologies, providing agents committing to them with the common semantic foundation required for effective interoperation.

Computer Communication Networks↗
PubMed1997

Information content of individual genetic sequences.

Related genetic sequences having a common function can be described by Shannon's information measure and depicted graphically by a sequence logo. Though useful for many purposes, sequence logos only show the average sequence conservation, and inferring the conservation for individual sequences is difficult. This limitation is overcome by the individual information ( R i) technique described here. The method begins by generating a weight matrix from the frequencies of each nucleotide or amino acid at each position of the aligned sequences. This matrix is then applied to the sequences themselves to determine the sequence conservation of each individual sequence. The matrix is unique because the average of these assignments is the total sequence conservation, ad there is only one way to construct such a matrix. For binding sites on polynucleotides, the weight matrix has a natural cut off that distinguishes functional sequences from other sequences. R i values are on an absolute scale measured in bits of information so the conservation of different biological functions can be compared with one another. The matrix can be used to rank-order the sequences, to search for new sequences, to compare sequences to other quantitative data such as binding energy or distance between binding sites, to distinguish mutations from polymorphisms, to design sequences of a given strength, and to detect errors in databases. The R i method has been used to identify previously undescribed but experimentally verified DNA binding sites. The individual information distribution was determined for E. coli ribosome binding sites, bacterial Fis binding sites, and human donor and acceptor splice junctions, among others. The distributions demonstrate clearly that the consensus sequence is highly unusual, and hence is a poor method to describe naturally occurring binding sites.

Animals↗
PubMed2000

Common object request broker architecture (CORBA)-based security services for the virtual radiology environment.

The US Army Great Plains Regional Medical Command (GPRMC) has a requirement to conform to Department of Defense (DoD) and Army security policies for the Virtual Radiology Environment (VRE) Project. Within the DoD, security policy is defined as the set of laws, rules, and practices that regulate how an organization manages, protects, and distributes sensitive information. Security policy in the DoD is described by the Trusted Computer System Evaluation Criteria (TCSEC), Army Regulation (AR) 380-19, Defense Information Infrastructure Common Operating Environment (DII COE), Military Health Services System Automated Information Systems Security Policy Manual, and National Computer Security Center-TG-005, "Trusted Network Interpretation." These documents were used to develop a security policy that defines information protection requirements that are made with respect to those laws, rules, and practices that are required to protect the information stored and processed in the VRE Project. The goal of the security policy is to provide for a C2-level of information protection while also satisfying the functional needs of the GPRMC's user community. This report summarizes the security policy for the VRE and defines the CORBA security services that satisfy the policy. In the VRE, the information to be protected is embedded into three major information components: (1) Patient information consists of Digital Imaging and Communications in Medicine (DICOM)-formatted fields. The patient information resides in the digital imaging network picture archiving and communication system (DIN-PACS) networks in the database archive systems and includes (a) patient demographics; (b) patient images from x-ray, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US); and (c) prior patient images and related patient history. (2) Meta-Manager information to be protected consists of several data objects. This information is distributed to the Meta-Manager nodes and includes (a) radiologist schedules; (b) modality worklists; (c) routed case information; (d) DIN-PACS and Composite Health Care system (CHCS) messages, and Meta-Manager administrative and security information; and (e) patient case information. (3) Access control and communications security is required in the VRE to control who uses the VRE and Meta-Manager facilities and to secure the messages between VRE components. The CORBA Security Service Specification version 1.5 is designed to allow up to TCSEC's B2-level security for distributed objects. The CORBA Security Service Specification defines the functionality of several security features: identification and authentication, authorization and access control, security auditing, communication security, nonrepudiation, and security administration. This report describes the enhanced security features for the VRE and their implementation using commercial CORBA Security Service software products.

Artificial Intelligence↗
PubMed2006

Stochastic approaches to understanding dissociations in inflectional morphology.

Computer modelling research has undermined the view that double dissociations in behaviour are sufficient to infer separability in the cognitive mechanisms underlying those behaviours. However, all these models employ multi-modal representational schemes, where functional specialisation of processing emerges from the training process. Targeted lesioning of different regions of functional specialisation leads to varied but predictable deficits in model performance. We argue that multi-modal representational schemes are not a necessary condition for the observation of double dissociations in an information processing system that shares resources across multiple tasks. Using a uni-modal representational system, we demonstrate that double dissociations may also result from stochastic processes. Lesioning experiments on a single-route, uni-modal connectionist model of regular and irregular noun and verb morphology confirm and extend earlier work demonstrating that selective impairment across tasks can result from damage to a distributed information processing system. A systematic investigation of the degree to which performance deteriorates across different inflectional classes reveals that simple and double dissociations can occur in this single-route, uni-modal model. An important prediction of the model is that double dissociations between regular and irregular inflection, resulting from stochastic processes should be extremely rare. However, they are particularly likely to occur when the researcher uses test batteries consisting of a small number of items. Given that cognitive neuropsychologists rarely provide details about the distribution of performance in a disordered population, it is concluded that a stochastic interpretation of double dissociations may have wider applicability than is normally supposed.

Alzheimer Disease↗
PubMed1989

Changing trends in drug use: the second follow-up of a local heroin using community.

The first Seadown study documented the way in which police action in closing down the cohort's central point for meeting and drug distribution had effectively destroyed the long established heroin distribution network. Throughout the period of low heroin availability the social network of the cohort was preserved as members developed a whole range of alternative coping styles (displacement activities) in compensation for the enforced abstinence caused by the heroin drought. During the period of observation heroin returned to Seadown initially through a small, unstable and informal distribution co-operative and stayed in this phase until a new central meeting place had been established. Thereafter once a pyramidal distribution network developed, most cohort members were able to modify or stop their displacement activities to accommodate the re-availability of heroin.

Cohort Studies↗
PubMed2004

Dose-volume conundrum for response of prostate cancer to brachytherapy: summary dosimetric measures and their relationship to tumor control probability.

PURPOSE: Although it is known that brachytherapy dose distributions are highly heterogeneous, the effect of particular dose distribution patterns on tumor control probability (TCP) is unknown. It is unlikely that clinical results will throw light on the question in the near future, given the long follow-up and detailed dosimetry required for each patient. We used detailed dose distribution data from 50 patients combined with radiobiologic parameters consistent with what is known about TCP curves for prostate cancer to study the changes in TCP that accompany gross dosimetric measures and particular dosing irregularities (e.g., moderate underdosing of large volumes vs. extreme underdosing of small volumes). METHODS AND MATERIALS: For each of the 50 patients with organ-confined prostate cancer who had undergone 125I prostate implants alone at our clinic, postimplant CT scans were obtained approximately 1 month after implantation. Dose distribution information was obtained from postimplant dosimetry. The percentage of the prostate volume receiving a specified dose was recorded from the respective differential dose-volume histograms in 10-Gy bins. In addition, the percentage of prostate volume underdosed at varying fractions of the prescription dose were determined, as was the minimal prostate dose. The log-normal distributions of the radiobiologic parameters [ln(initial clonogen number), alpha, and alpha/beta] were adjusted so that the predicted population parameters (steepness and location) of the dose-response curves for external beam radiotherapy agreed with the published estimates. The variability in the dose-volume details was increased by scaling the dose distributions by factors ranging from 0.7 to 1.5, thereby simulating, for each of the patients, nine new patients with different total doses but identical relative distributions of the dose over the voxels. Radiobiologic variability between the selected dose distributions was then removed by averaging >50 randomly chosen sets of radiobiologic parameters from the log-normal distributions to estimate the TCP for each of the dose distributions, giving some insight into the TCP variations with conventional dosimetric indexes and different patterns of underdosing. RESULTS: Using the 450 dose distributions created by expanding the 50-patient data set, the volume of the prostate that was extremely underdosed (between 50% and 70% of the prescription dose) was related to the volume that was moderately underdosed (between 80% and 100% of the prescription dose). We found that the individual TCP is greatly dependent on the inhomogeneous dose distribution and the dosimetric indexes, such as the volume of prostate receiving 100% of the prescribed dose (V100) and the maximal dose received by 90% of the prostate volume (D90), which, by themselves, are not always accurate predictors of control probabilities. In a multivariate analysis of the dependence of TCP on these parameters (V100, D90, minimal dose, and moderately and severely underdosed volumes), only D90 and the minimal dose were statistically significant. Generally speaking, however, a lower minimal dose means a lower TCP. CONCLUSION: The work described here was an hypothesis-generating study. Our results showed that even if the V100 and D90 are nearly identical for 2 patients, there can be (and frequently are) significant differences in the dose distributions in the subvolumes of the prostate. Under simulated dose-response conditions (i.e., with variations in the dose distribution), the D90 and minimal dose significantly affected the TCP but the V100 and the volumes moderately or severely underdosed did not. In general, one must consider the totality of the dose distribution to evaluate the dosimetric quality of a low-dose-rate prostate implant. TCP is not a monotonic function of extreme or moderate underdosing. In some instances, extreme underdosing of relatively small volumes may result in a greater TCP than moderate underdosing of relatively large volumes and vice versa.

Brachytherapy↗
PubMed2002

Decoupled stochastic parallel gradient descent optimization for adaptive optics: integrated approach for wave-front sensor information fusion.

A new adaptive wave-front control technique and system architectures that offer fast adaptation convergence even for high-resolution adaptive optics is described. This technique is referred to as decoupled stochastic parallel gradient descent (D-SPGD). D-SPGD is based on stochastic parallel gradient descent optimization of performance metrics that depend on wave-front sensor data. The fast convergence rate is achieved through partial decoupling of the adaptive system's control channels by incorporating spatially distributed information from a wave-front sensor into the model-free optimization technique. D-SPGD wave-front phase control can be applied to a general class of adaptive optical systems. The efficiency of this approach is analyzed numerically by considering compensation of atmospheric-turbulence-induced phase distortions with use of both low-resolution (127 control channels) and high-resolution (256 x 256 control channels) adaptive systems. Results demonstrate that phase distortion compensation can be achieved during only 10-20 iterations. The efficiency of adaptive wave-front correction with D-SPGD is practically independent of system resolution.

Journal Article↗