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PubMed2003

Programming secure mobile agents in healthcare environments using role-based permissions.

The healthcare environment consists of vast amounts of dynamic and unstructured information, distributed over a large number of information systems. Mobile agent technology is having an ever-growing impact on the delivery of medical information. It supports acquiring and manipulating information distributed in a large number of information systems. Moreover is suitable for the computer untrained medical stuff. But the introduction of mobile agents generates advanced threads to the sensitive healthcare information, unless the proper countermeasures are taken. By applying the role-based approach to the authorization problem, we ease the sharing of information between hospital information systems and we reduce the administering part. The different initiative of the agent's migration method, results in different methods of assigning roles to the agent.

Access to Information↗
PubMed2000

Cortical potential distributions and information processing.

The use of sets of spatiotemporal cortical potential distributions (CPDs) as the basis for cognitive information processing results in a very large space of cognitive elements with natural metrics. Results obtained from current source density (CSD) analysis suggest that in the CPD picture, action potentials may make only a relatively minor contribution to the brain's code. In order to establish if two CPDs are close, we consider standard metrics in spaces of continuous functions, and these may be employed to ascertain if two stimuli will be identified as the same. The correspondence between the electrical activity within brain regions, including not only action potentials but all postsynaptic potentials (PSPs), and CPDs is considered. We examine the possibility of using the CSD approach to find potential distributions using the descriptive approach in which precise sets of times are ascribed to the occurrence of action potentials and PSPs. Using metrics in the multidimensional space of paths of collections of point processes, we show that closeness of CPDs is implied by closeness of sets of spike times and PSP times if a certain metric is used but not others. We also set forth a dynamical model consisting of a system of reaction-dif fusion equations for ionic concentrations coupled with nerve membrane potential equations and active transport systems. Making the approximation of a descriptive approach, the correspondence between sets of spike times and PSP times and CPDs is obtained as with the CSD method. However, since it is not possible to ascribe precise times to the occurrence of PSPs and action potentials, the descriptive approach cannot be used to describe the configuration of electrical activity in cortical regions accurately. We also discuss how the CPD framework relates to the binding problem and submillisecond timing.

Algorithms↗
PubMed1982

Transmitters involved in central processing of nociceptive information.

Distribution studies suggest that substance P is a transmitter released by nociceptive primary afferent fibres. Acceptance of this role, however needs more electro-physiological comparisons of the effects of substance P and the transmitter released by primary afferents on the membrane properties of dorsal horn neurones. The transmission of impulses from nociceptive afferents to supraspinal areas is subject to inhibition of both segmental and supraspinal origin. Segmental inhibition probably involves glycine and gamma-aminobutyric acid as transmitters. Of supraspinal inhibitions investigated in the cat none have been shown to involve amino acids, enkephalins or 5-hydroxytryptamine but there is evidence to suggest a role for noradrenaline.

Animals↗
PubMed1991

AIDS in California family medicine. Changing experiences, knowledge, and geographic distribution.

Information regarding practice patterns specific to acquired immunodeficiency syndrome (AIDS) was obtained in 1988 from 1774 family physicians in California using a mail survey. Data were analyzed across the following county groupings: Los Angeles County, other counties in standard metropolitan statistical areas, and counties outside standard metropolitan statistical areas. Comparisons were made with the data from a telephone survey conducted in 1986. Differences over time were analyzed. By 1988, the percentage of physicians treating or referring patients for possible AIDS had more than doubled in counties outside standard metropolitan statistical areas. The percentage of physicians reporting one or more diagnosed cases of AIDS had tripled, a finding that suggests the importance of AIDS in family medicine is increasing at a rapid rate. In addition, survey results indicate that a majority of those surveyed still lack the AIDS-related knowledge and competency necessary to effectively deal with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Factors promoting completion of advance directives in the hospital.

BACKGROUND: The 1991 Patient Self-Determination Act required health care providers to give patients information about advance directives. OBJECTIVES: To investigate whether the requirement to distribute information to hospital patients increased completion of the health care proxy. To also explore factors that might influence use of advance directives, including demographic variables and methods of informing patients about the directives. PATIENTS AND METHODS: We interviewed 419 randomly selected patients who were admitted for a planned admission to two tertiary care, teaching hospitals. Patients at one hospital received proxy information before the day of admission, at a pretesting visit, or by mail. The other hospital distributed the proxy information only on the day of admission. RESULTS: Before receiving hospital materials, 17% of all patients had completed proxies. After receiving hospital proxy forms, an additional 40% completed proxies at the hospital that distributed forms before the day of admission. Only 4% of the patients completed proxies at the hospital that distributed information only on the day of admission. The most frequently cited barrier to completion of a proxy was not seeing the form. Few patients said they did not want to think about the subject. CONCLUSIONS: Completion rates for advance directives may be markedly improved by altering the time for distributing information to patients admitted to the hospital for a planned admission. Patients were more likely to complete a proxy in the hospital that distributed the form in advance of the day of admission, a result that was unexplained by other variables in the study. Although many patients would prefer to receive information about advance directives during an office visit with a physician, hospitalization can provide a valuable opportunity for many patients to complete directives.

Adult↗
PubMed1998

Results of European projects improving security of distributed health information systems.

The challenge for improvement of quality and efficiency of health care systems causes the development and promotion of "Shared Care" in all developed countries. Distribution, decentralisation, and specialisation of health care must be joint with an extended communication and co-operation between the different care providers. Fulfilling the shared care paradigm, care supporting health information systems has to be distributed, interoperable, and scaleable too. Communication and co-operation across organisational, regional, and even national boundaries is bearing high threats and risks regarding security and privacy of medical and personal information of both patients and health professionals. Involved in several security projects funded by the European Union, the Medical Informatics Department and the regional Clinical Cancer Registry at the University of Magdeburg are piloting a secure regional distributed medical record system for cancer diseases. Requirements, solutions, and experiences are presented and discussed.

Computer Communication Networks↗
PubMed2005

Similarity of interspike interval distributions and information gain in a stationary neuronal firing.

The Kullback-Leibler (KL) information distance is proposed for judging similarity between two different interspike interval (ISI) distributions. The method is applied by a comparison of four common ISI descriptors with an exponential model which is characterized by the highest entropy. Under the condition of equal mean ISI values, the KL distance corresponds to information gain coming from the state described by the exponential distribution to the state described by the chosen ISI model. It has been shown that information can be transmitted changing neither the spike rate nor coefficient of variation (CV). Furthermore the KL distance offer an indication of the exponentiality of the chosen ISI descriptor (or data): the distance is zero if, and only if, the ISIs are distributed exponentially. Finally an application on experimental data coming from the olfactory sensory neurons of rats is shown.

Action Potentials↗
PubMed1996

Managing the operation of open distributed laboratory information systems.

This paper examines how the concepts and designs of workflow management systems and distributed systems management can be integrated and customized to manage open laboratory computing services. The paper outlines the objectives of managing laboratory computing services and identifies techniques and designs which facilitate this management. The paper also outlines the implementation of an open laboratory service management system.

Clinical Laboratory Information Systems↗
PubMed2003

DATStats: results from 85 studies using the Drug Abuse Treatment Cost Analysis Program.

The Drug Abuse Treatment Cost Analysis Program (DATCAP) was developed and launched in the early 1990s to help addiction researchers and administrators estimate the economic costs of substance abuse interventions. This paper presents summary results from 85 DATCAPs completed over the past 10 years. After first grouping the DATCAPs into 9 treatment modalities, cost measures (normalized to 2001 dollars) are reported along with client caseload information. Additionally, the distribution of costs across 6 resource categories is presented for each of the treatment modalities. The average weekly economic cost per client ranged from 82 US dollars per week for outpatient drug court interventions to 1,138 US dollars per week for adolescent residential treatment. As expected, labor was overwhelmingly the most utilized resource across all modalities, ranging from 48% to 88% of total economic cost. Addiction researchers, program administrators, and policymakers now have cost estimates and resource distribution information for various treatment modalities serving diverse populations.

Adolescent↗
PubMedDate not supplied

Neurocognitive networks and selectively distributed processing.

The association cortex of the human brain can be divided into unimodal and transmodal components. Unimodal (modality-specific) cortical areas are subdivided into upstream regions specialized for encoding unitary features of experience and downstream regions which are specialized for encoding composite features. Modality-specific features lead to multimodal knowledge through the mediation of transmodal areas in the brain. These transmodal areas include cortical regions that are conventionally designated as heteromodal, paralimbic and limbic cortex. Contrary to earlier formulations, it is no longer thought that these transmodal areas contain a convergent residue of knowledge. Instead, it appears that the role of these transmodal areas is to contain a road map for the multifocal binding and calling up of distributed information in multiple modalities. Knowledge can thus be encoded in a flexible distributed rather than rigid convergent form. Observations on patients with focal neurological lesions indicate that transmodal areas act like neural hubs (or gateways) for accessing critical domains of knowledge rather than as dedicated centers for specific cognitive functions. In the processes related to memory, a limbic structure such as the hippocampus does not act as a bank for specific memories but as a critical node for accessing distributed information related to recently acquired experience. Damage to a sufficient volume of the limbic system interferes with the coherence of recall and storage even though the constituent fragments of the corresponding experiences may remain stored quite well in other parts of the brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral Cortex↗
PubMed1989

The temporal distribution of stimulus information in the visual evoked potential.

Research in psychophysics (Bloch's law) and perceptual experiments concerned with the integration of successively presented stimuli suggest that the perception of form is a process that occurs over a period of as much as 200-300 msec. Such results prompted the question of whether the visual evoked potential (VEP) might contain information about the distribution over time of perceptual processing. Subjects viewed lines formed from combinations of three lengths and four angles while the EEG was recorded. Analysis of the VEPs indicated that the length and angle of the lines produced temporal distributions of information in the VEP and that the distributions for length and angle were somewhat different. The major difference was that the processing of angle begins earlier and is completed sooner than the processing of length. A conclusion of the experiment was that an alternative or supplement to analyzing VEPs for specific waveform features is to consider the encoding of stimulus information in the VEP as a density or concentration over time.

Adult↗
PubMed1985

How does flow cytometry express Gaussian distributed biological information?

The analogue-to-digital conversion step in flow cytometric analysis introduces a positive skew into the distribution of any measured parameter. In this communication we describe a semi-analytical method to determine if a distribution skewed by the analogue-to-digital conversion step is compatible with a Gaussian origin. The procedure involves determining the errors associated with calculating the coefficient of variation from the skewed distribution and applying systematic corrections. The method was tested with a number of experimental data sets and is illustrated with 3 distributions. One of these was not compatible with a Gaussian origin, but the other 2 were, in spite of considerable positive skewness in the data.

Blood Cell Count↗
PubMedDate not supplied

Exchanging health information: local distribution, national coordination.

The fragmentation of our health care system, our need to accommodate the diversity of existing health information exchanges, the lack of consistent implementation of clinical information standards, and the need to protect patients' privacy and maintain trust are all challenges to overcome in achieving broad-scale interoperable health information exchange. We propose several steps to coordinate information sharing among regional and other networks through universal adherence to a basic framework of policies and standards. The critical policy action is the identification of a "common framework" of standards and policies, maintained by a new Standards and Policy Entity that reflects both public- and private-sector participation.

Community Health Planning↗
PubMed2006

Diazepam pharamacokinetics from preclinical to phase I using a Bayesian population physiologically based pharmacokinetic model with informative prior distributions in WinBUGS.

Modelling is an important applied tool in drug discovery and development for the prediction and interpretation of drug pharmacokinetics. Preclinical information is used to decide whether a compound will be taken forwards and its pharmacokinetics investigated in human. After proceeding to human little to no use is made of these often very rich data. We suggest a method where the preclinical data are integrated into a whole body physiologically based pharmacokinetic (WBPBPK) model and this model is then used for estimating population PK parameters in human. This approach offers a continuous flow of information from preclinical to clinical studies without the need for different models or model reduction. Additionally, predictions are based upon single parameter values, but making realistic predictions involves incorporating the various sources of variability and uncertainty. Currently, WBPBPK modelling is undertaken as a two-stage process: (i) estimation (optimisation) of drug-dependent parameters by either least squares regression or maximum likelihood and (ii) accounting for the existing parameter variability and uncertainty by stochastic simulation. To address these issues a general Bayesian approach using WinBUGS for estimation of drug-dependent parameters in WBPBPK models is described. Initially applied to data in rat, this approach is further adopted for extrapolation to human, which allows retention of some parameters and updating others with the available human data. While the issues surrounding the incorporation of uncertainty and variability within prediction have been explored within WBPBPK modeling methodology they have equal application to other areas of pharmacokinetics, as well as to pharmacodynamics.

Algorithms↗
PubMed1986

Overview of an architectural approach to the development of the Johns Hopkins Hospital distributed clinical information system.

The Johns Hopkins Hospital has initiated an ambitious program to apply modern technologies to the development of a new, comprehensive clinical information system. Since many components of a system exist and since the JHH management is decentralized, a distributed, networked system is being built. To properly accomplish this task an architectural basis for strategic systems planning was developed. This paper reviews briefly the layered architectural approach.

Computer Communication Networks↗
PubMedDate not supplied

Determining parameters of lognormal distributions from minimal information.

The lognormal distribution has a number of properties that do not lend themselves to simple "back-of-the-envelope" calculations. Mathematical relationships are presented for the basic parameters of the large population lognormal distribution as a function of characteristics available to, or needed by, the risk analyst. A freeware computer program called LOGNORM4 has been written to take the tedium out of determining various characteristics of lognormal distributions, given 1 of 15 sets of values that uniquely specify a lognormal distribution.

Data Interpretation, Statistical↗
PubMed2003

Do measures of body fat distribution provide information on the risk of type 2 diabetes in addition to measures of general obesity? Comparison of anthropometric predictors of type 2 diabetes in Pima Indians.

OBJECTIVE: To investigate which anthropometric measurements of obesity best predict type 2 diabetes in a population of Pima Indians and whether additional information on diabetes risk could be obtained by combining measures of general obesity with measures of body fat distribution. RESEARCH DESIGN AND METHODS: We conducted a prospective study of 624 men and 990 nonpregnant women >18 years of age without diabetes. Subjects were followed a mean of 5.25 years for the development of type 2 diabetes (using 1997 American Diabetes Association criteria). RESULTS: A total of 322 new cases of type 2 diabetes (107 men and 215 women) were diagnosed during follow-up. Baseline obesity measurements were highly correlated and predicted diabetes in proportional hazards models adjusted for age. BMI had the highest hazard ratio in men and women, with age-adjusted hazard ratios per SD of 1.73 (95% CI 1.44-2.07) and 1.67 (1.45-1.91), respectively. According to receiver-operating characteristic analysis, BMI and waist-to-height ratio were the best predictors of diabetes in men, while in women BMI, waist-to-height ratio, waist circumference, and waist-to-thigh ratio were the best predictors. The predictive abilities of models containing BMI were not significantly improved by including other measures of general obesity or measures of the body fat distribution. CONCLUSIONS: Throughout its range, BMI was an excellent predictor of type 2 diabetes risk in Pima Indians and was not significantly improved by combining it with other measures of general adiposity or body fat distribution.

Adipose Tissue↗