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PubMed2006

National population based HIV prevalence surveys in sub-Saharan Africa: results and implications for HIV and AIDS estimates.

BACKGROUND: Sentinel surveillance among pregnant women attending antenatal clinics (ANCs) has been the main source of information on HIV trends in sub-Saharan Africa. These data have also been used to generate national HIV and AIDS estimates. New technologies and resources have allowed many countries to conduct national population based surveys that include HIV prevalence measurement, as an additional source of information on the AIDS epidemic. METHODS: The authors reviewed the reports of 20 national population based surveys from 19 countries carried out in sub-Saharan Africa since 2001. They examined the sampling methodology, HIV testing and response rates, and female:male and urban:rural prevalence ratios. They also constructed adjusted prevalence scenarios assuming different relative risks for survey non-responders. RESULTS: The national population based surveys vary considerably in quality, as reflected in the household response rate (ranging from 75.4% to 99.7%), women's testing rate (ranging from 68.2% to 97.3%), and men's testing rate (ranging from 62.2% to 95.4%), while for some surveys detailed response information is lacking. While 95% confidence intervals around the female:male and urban:rural prevalence ratios in individual countries are large, the median female:male ratio of the combined set of surveys results is 1.5 and the median urban:rural ratio 1.7. A scenario assuming that non-responders have twice the HIV prevalence of those who fully participated in the survey suggests that individual non-response could result in an adjusted HIV prevalence 1.03 to 1.34 times higher than the observed prevalence. CONCLUSIONS: Population based surveys can provide useful information on HIV prevalence levels and distribution. This information is being used to improve national HIV and AIDS estimates. Further refinements in data collection, analysis, and reporting, combined with high participation rates, can further improve HIV and AIDS estimates at national and regional level.

Adolescent↗
PubMed1994

Value-added services that increase physicians' intent to refer patients to an outpatient nutrition clinic.

We surveyed 378 practicing physicians to identify value-added services that would increase their patient referrals to registered dietitians at an outpatient nutrition clinic. One hundred thirty-nine completed surveys were used in compiling the results. In the survey we presented 16 value-added services specifically designed to overcome physicians' barriers to referral as noted in the literature, and we requested demographic information. Frequency distributions revealed that the services physicians most strongly agreed would increase their referrals were help patients receive reimbursement from third-party graphic information. Frequency distributions revealed that the services physicians most strongly agreed would increase their referrals were help patients receive reimbursement from third-party payers (92.1%), provide a free initial meeting with the patient (82.4%), and offer group cooking classes (81.3%). The services physicians most strongly disagreed would increase their referrals were provide a list of physicians currently using the outpatient nutrition clinic who can provide recommendations (33.1%) and provide a free consultation for the physician (30.2%). Our findings indicate that (a) value-added services most likely to stimulate referrals are those that moderate the cost of nutrition counseling, document its effectiveness, and provide skills training in the form of cooking classes, and (b) value-added services least likely to stimulate referrals are those that require physicians' time.

Ambulatory Care Facilities↗
PubMed1997

"Academic drug-detailing": from project to practice in a Swedish urban area.

OBJECTIVES: To develop and test the long-term feasibility of an interdisciplinary independent drug information service providing both written and oral drug information to physicians in an urban area of Sweden (> 400,000 inhabitants). METHODS: A drug information service was developed encouraging a cooperative approach between a department of clinical pharmacology, general practitioners (GPs), pharmacists, and Drug and Therapeutic Committees. Scientifically-based drug information was condensed and interpreted by a team and presented in both written and oral form. In one part of the area, both oral and written information was provided, while in another part of the area, only written information was distributed. Questionnaires and one prescription survey were performed to elucidate the knowledge and attitudes of the GPs regarding drug treatment of one condition (urinary tract infection, UTI, and norfloxacin were used as examples), as well as their opinion of our services. RESULTS: Over a period of 10 years, 75 issues of a drug bulletin (2000 copies) were distributed. Oral producer-independent drug information, provided jointly by a GP and a pharmacist, was given on 16 occasions in each of 30 health centres (150 GPs). Around 80% of the GPs participated in the meetings. Of these GPs, 75% found the service important for their daily work. A majority of the GPs had prescribed the test drug, norfloxacin, not a first-line drug according to local recommendations, 1 year after approval. A significantly lower proportion of prescribers were observed in the area where the GPs had been provided with both written and oral information regarding recommended treatment (including first-line drugs) for uncomplicated cystitis. The approximate cost for this service in 1995 was SEK 0.685 million (USD 0.1 million); the prescribing costs of the 150 GPs were estimated at SEK 255 million per year. This means that the cost of the service per GP is only around 0.3% of normal prescribing costs. CONCLUSION: Over a period of 10 years the information/education method described here has proven sustainable and feasible in terms of providing the information, regarding participation of the target group GPs in the oral sessions, and regarding integration of the service into the existing health care system.

Anti-Infective Agents↗
PubMed1998

The metabolic cost of neural information.

We derive experimentally based estimates of the energy used by neural mechanisms to code known quantities of information. Biophysical measurements from cells in the blowfly retina yield estimates of the ATP required to generate graded (analog) electrical signals that transmit known amounts of information. Energy consumption is several orders of magnitude greater than the thermodynamic minimum. It costs 10(4) ATP molecules to transmit a bit at a chemical synapse, and 10(6)-10(7) ATP for graded signals in an interneuron or a photoreceptor, or for spike coding. Therefore, in noise-limited signaling systems, a weak pathway of low capacity transmits information more economically, which promotes the distribution of information among multiple pathways.

Action Potentials↗
PubMed1998

Using the Internet to educate consumers about health care choices.

Employers are increasingly using the internet to distribute comparative information to employees, dependents and retirees as it is often more cost-effective and can be easily updated and customized to meet users' needs. Health Pages, a New York City-based consumer health information publisher, has been working with employers to distribute health education articles and comparative information nationwide. Working with employers such as General Motors, Boeing/McDonnell Douglas, US WEST and Southern California Edison, Health Pages has created customized websites providing a variety of benefit and comparative managed care plan/physician information via corporate intranets. To reach a broader audience, Health Pages also works with newspapers and magazines. Future activities in information dissemination will include aggregating performance information into simpler categories and allowing greater user interactivity.

Choice Behavior↗
PubMed1988

Electron microscopy of nucleic acid.

Electron microscopy (EM) of nucleic acids was first described by Kleinschmidt and Zahn 1959 (1). By complexing duplex DNA with basic proteins and spreading the complexed DNA onto the surface of an aquous phase it was possible to obtain well stretched DNA molecules that could be examined by EM. Addition of formamide to DNA spreading solution as well as to hypophase prevented single-stranded DNA and RNA from forming secondary structures thus providing conditions for analysis of these molecules. EM studies have provided information about molecular weight, molecular configuration and homogeneity/heterogeneity of the DNA preparations examined. Furthermore, intramolecular heterogeneity in base sequence could be analyzed by partial denaturation of duplex DNA. By partial denaturation mapping information of the orientation of DNA molecules was obtained. Sequence homology between two DNA molecules were studied by heteroduplex analyses where the two DNAs to be studied were denatured to full strand separation followed by reassociation. This method has been widely used to analyze DNA mutations, and to discover sequence homologies within a DNA molecule or between two DNA molecules. Heteroduplex analyses between DNA and RNA (R-loop formation) provided information about distribution of ribosomal RNA genes and gave the first information of eukaryotic post transcriptional processing of mRNA. Also the various modes for DNA replication and transcription were studied by EM. It is possible to study duplex DNA not complexed by basic proteins by EM. The DNA is then adsorbed to an activated carbon film and rotary shadowed with finely grained metals to enhance the contrast. Using this method it was possible to study binding of proteins to DNA. This method was also used in the study of chromatin structure where it provided information of the size and distribution of nucleosomes as well as packaging of DNA in chromatin fibres. The complicated nature of DNA strand exchange and repair reactions was studied by in-vitro systems where EM analysis was used in the description of the presynoptic filament and structure of the joined molecules. Furthermore, EM provided the first direct evidence for the existence of the paranemic joint, where the DNA strands are joined without Watson-Crick base-pairing.

Animals↗
PubMed2005

Prior distributions for the intracluster correlation coefficient, based on multiple previous estimates, and their application in cluster randomized trials.

Numerous estimates for the intracluster correlation coefficient (ICC) are available in research databases and publications. When planning a cluster randomized trial, an anticipated value for the ICC is required; currently, researchers base their choice informally on the magnitude of previous ICC estimates. In this paper, we make use of the wealth of ICC information by formally constructing informative prior distributions, while acknowledging the varying relevance and precision of the estimates available. Typically, for a planned trial in a given clinical setting, multiple relevant ICC estimates are available from each of several completed studies. Our preferred model allows for the imprecision in each ICC estimate around its underlying true value and, separately, allows for the similarity of ICC values from the same study. The relevance of each previous estimate to the planned clinical setting is considered, and estimates corresponding to less relevant outcomes or population types are given less influence. We find that such downweighting can increase the precision of the anticipated ICC. In trial design, the prior distribution constructed allows uncertainty about the ICC to be acknowledged, and we describe how to choose a design that provides adequate power across the range of likely ICC values. Prior information on the ICC can also be incorporated in analysis of the trial data, when taking a Bayesian approach. The methods proposed enable available ICC information to be summarised appropriately by an informative prior distribution, which is of direct practical use in cluster randomized trials.

Bayes Theorem↗
PubMedDate not supplied

Improving the public health/physician partnership for influenza vaccination.

BACKGROUND: Alberta doctors can request supplies of publicly funded influenza vaccine to administer to patients who meet provincial program criteria. PURPOSE: To describe the proportions of Alberta family doctors who vaccinate patients, the sources from which they obtain vaccine and their evaluation of public health influenza vaccination program components. METHODS: Cross-sectional postal survey, 2003. Doctors were asked to complete a nine-page questionnaire or to answer a one-page "mini-survey". The proportion of physicians who vaccinated patients against influenza was estimated separately for the main questionnaire and the mini-survey. Frequencies and cross-tabulations were used to examine sources of vaccine supply and physician ratings of five aspects of influenza vaccine program services provided by Regional Health Authorities (RHA). RESULTS: The survey response rate was 52.3% (1387/2650); an additional 14% (372) returned a mini-survey. The proportion of respondents who vaccinated one or more patients against influenza in the fall of 2002 was 81.5% for the main questionnaire and 83.1% for the mini-survey. Vaccine was most commonly obtained from the RHA. Three items were rated as poor/fair by more than 10% of respondents: provision of information for distribution to patients (37%), timeliness of vaccine delivery to offices (16%) and vaccine availability over the entire influenza season (18%). Item ratings varied by RHA but provision of information for distribution to patients was consistently a problem. CONCLUSION: A high priority should be placed on improving resources for doctors to give to patients, timeliness of vaccine deliveries to doctors' offices and vaccine availability over the entire season.

Alberta↗
PubMed1988

Information influences the pattern of eye fixations during sentence comprehension.

How does the pattern of eye fixation vary as an informative part of a word is encountered? If the processing of information lags behind the movement of the eyes, then we should expect no variation in the pattern; but if processing is immediate, then the movements of the reader's eyes should correspond to the distribution of information being inspected. An experiment is reported which examined the ways that the text ahead of the point of current fixation can be used to guide the eyes to future fixations, by monitoring fixations during a sentence comprehension task. The patterns of eye fixations upon words with uneven distributions of information (where, for example, words predictable from the sight of their first few letters but not from their last few letters are defined as containing informative beginnings) were observed, and it was found that more and longer fixations were produced when subjects looked at the informative parts of words, particularly at the informative endings of words. The results support the suggestion that eye movements are under the moment-to-moment control of cognitive mechanisms.

Adult↗
PubMed1995

Development of distributed image database combined with clinical information in hospital information system.

We have developed a distributed image database system composed of the data in our medium-scale PACS that provides diagnostic-quality images and the data in our HIS. INFORMIX software was used to construct the distributed relational database. The data in HIS were retrieved using several programs written in COBOL. Image data in PACS were retrieved using ACR-NEMA protocols. The data retrieved from the HIS database involved medication, disease entities, laboratory test results, etc. Therefore, the image data on a given patient can be retrieved by specifying the name of the disease in our database system. Our method offers a practical one to make a global database system to maintain the integrity of the data in the HIS and the PACS. The combination of image data and disease made it quite easy to make a sample database for developing a computer-aided diagnostic system.

Computer Communication Networks↗
PubMed1992

Distributed processing of sensory information in the leech. III. A dynamical neural network model of the local bending reflex.

The subpopulation of identified interneurons in the local bending reflex receive multiple inputs from dorsal and ventral mechanoreceptors and have outputs to dorsal and ventral motor neurons. Their connections suggest a distributed processing mechanism in which withdrawal from dorsal, ventral, or lateral stimuli is controlled by a single population of approximately 40 multifunctional interneurons, but it is unclear whether additional interneurons dedicated to particular inputs are needed to account for each kind of bend. We therefore asked whether a model could be constructed that reproduced all behaviors without dedicated interneurons. Interneurons in the model were constrained to receive both dorsal and ventral inputs. Connection strengths were adjusted by gradient descent optimization until the model reproduced the amplitude and time course of motor neuron synaptic potentials in intracellular recordings of the response to many different stimuli. After optimization, the similarity between model and identified interneurons showed that additional dedicated interneurons are not necessary to produce all forms of the behavior. Successful optimization of networks with many fewer interneurons showed that the 40-interneuron network is redundant, raising the possibility that the interneurons have additional functions. Finally, optimizing networks with additional constraints produced better matches to some of the identified interneurons and showed that local bending can be produced by two populations of interneurons: one with outputs consistent with dorsal bending, the other with ventral bending. This suggests a simple model in which two principal types of interneurons produce many different behaviors and predicts the type of interneuron that remains to be identified.

Animals↗
PubMed1995

The health care professional multimedia workstation: development and integration issues.

Workstations for health care professionals provide access to distributed healthcare information systems. They are complex systems that have to manage, in a unified framework, the distributed and multimedia information needed for optimal patient care. The objective is to provide the end-user with a virtual and unified device that conceals the complexity of the underlying information system. Integration and reuse of modular software components are important in the development of such a workstation. A reference set of evaluation criteria is proposed that includes functional, technical, organizational, medical, cultural and ethical, economic and industrial components.

Computer Communication Networks↗
PubMedDate not supplied

Building communication networks: international network for the study and prevention of emerging antimicrobial resistance.

The global nature of antimicrobial resistance and the failure to control the emergence of resistant organisms demand the implementation of a global surveillance program involving both developed and developing countries. Because of the urgent need for infection control interventions and for rapid distribution of information about emerging organisms, we initiated the International Network for the Study and Prevention of Emerging Antimicrobial Resistance (INSPEAR). Its main objectives are to serve as an early warning system for emerging antimicrobial-drug resistant pathogens, to facilitate rapid distribution of information about emerging multidrug-resistant pathogens to hospitals and public health authorities worldwide, and to serve as a model for the development and implementation of infection control interventions.

Communicable Disease Control↗
PubMed1995

Global dimensional complexity of the EEG in healthy volunteers.

In contrast to the single-channel dimensional complexity, the global dimensional complexity is calculated from a multichannel EEG. The intention with the method is to measure the spatial distribution of information processing in the brain. The method seems to be of interest in psychopharmacological research, but the interpretation of the results in physiological terms is rather difficult. To get a more detailed information on the physiological significance of the EEG complexity measures, the influence of well-known physiological factors was studied in a group of 14 healthy subjects aged from 1.5 to 61 years. It was found that the correlation dimension was somewhat higher in older individuals, but the correlation with age was not statistically significant. However, the global correlation dimension was significantly lower during full alertness than during drowsiness. These results might reflect the changes in spatial structure of information processing, a high complexity suggesting a 'disorganisation' during drowsiness. As regards the age-dependent changes of the correlation dimension, the spatial 'flexibility' of information processing was also studied, using the differences between the 'alert' and 'drowsy' parts of the same EEG as indicator. It was found that the differences 'drowsy minus alert' were significantly related to age. A plausible interpretation seems to be that the spatial distribution of information processing is more changeable, or more flexible, in adults than in children.

Adolescent↗
PubMed2001

Bayesian methods for cluster randomized trials with continuous responses.

Bayesian methods for cluster randomized trials extend the random-effects formulation by allowing both the use of external evidence on parameters and straightforward relaxation of the standard normality and constant variance assumptions. Care is required in specifying prior distributions on variance components, and a number of different options are explored with implied prior distributions for other parameters given in closed form. Markov chain Monte Carlo (MCMC) methods permit the fitting of very general models and the introduction of parameter uncertainty into power calculations. We illustrate these ideas using a published example in which general practices were randomized to intervention or control, and show that different choices of supposedly 'non-informative' prior distributions can have substantial influence on conclusions. We also illustrate the use of forward simulation methods in power calculations with uncertainty on multiple inputs. Bayesian methods have the potential to be very useful but guidance is required as to appropriate strategies for robust analysis. Our current experience leads us to recommend a standard 'non-informative' prior distribution for the within-cluster sampling variance, and an independent prior on the intraclass correlation coefficient (ICC). The latter may exploit background evidence or, as a reference analysis, be a uniform ICC or a 'uniform shrinkage' prior.

Bayes Theorem↗
PubMed1989

A general rule for ranged series of codon frequencies in different genomes.

Information science widely uses descriptions of the distribution of information units (words) according to the frequency of occurrence with the help of a corresponding ranged series, i.e., the sequence of occurrence frequencies p1, p2, ..., pr as taken in decreasing order. A model called the Zipf rule or Zipflaw is the most commonly used. In this model pr is inversly proportional to a certain degree of range r: pr = C/r2 (C, z greater than 0). Upon analysis, the correspondence of codon distribution and the Zipf model is found unsatisfactory. The distribution of letters (in English and some other languages) by the occurrence frequency does not obey the Zipf rule either. A new model is proposed for a similar distribution in which pr = C.(ln(n + 1)-ln r), where n is the quantity of various symbols (codons). This dependence is approximated by a straight line not in the co-ordinate system (ln r, ln p), like the Zipf model, but in the (ln r, p) system of co-ordinates. It is shown on the basis of statistical criteria that this model is in good agreement with the ranged series of codon frequencies for the best-studied genoms to date. This result may be regarded as an additional reason in favor of the codon-letter analogy (not the codon-word analogy) in genetic texts.

Animals↗
PubMed2005

Estimation of fugitive lead emission rates from secondary lead facilities using hierarchical Bayesian models.

Fugitive emissions from secondary lead recovery facilities are difficult to estimate and can vary significantly from site to site. A methodology is presented for estimating fugitive emissions using back inference from observed ambient concentrations at nearby monitors, in conjunction with an atmospheric transport and dispersion model. Observed concentrations are regressed against unit source-monitor transfer terms computed by the model, and the fitted parameters of the regression equation include the background ambient lead concentration, the fugitive lead emission rate, and (when stack emissions are assumed to be unknown) the stack lead emission rate. The methodology is implemented at three sites, one each in Florida, Texas, and New York. A hierarchical Bayesian method is used to estimate the parameters of the model, allowing inferences to be made for both site-specific values and multisite (national) distributions of fugitive emissions and background concentrations. Informed prior distributions must be specified for the background lead concentrations and for fugitive and stack emission rates in order to obtain stable estimates. Sensitivity analyses with alternative priors indicate that posterior estimates of background concentrations and fugitive emission rates are relatively insensitive to the assumed priors, although estimated stack emission rates can vary with alternative priors, especially for the New York facility, where the stack emission rate is highly uncertain and poorly resolved by the model. The fugitive lead emission rates estimated for the sites are comparable to, or in some cases (especially Texas and New York) likely larger than the stack emissions that are determined for these facilities. An aggregate predictive distribution is derived for the average fugitive lead emission rate from secondary lead smelting facilities, with a median value of 9.2 x 10(-7) g Pb/m2/sec, and a 90% credible interval from 2.1 x 10(-7)-5.3 x 10(-6) g Pb/m2/sec. This wide range reflects both the variation in fugitive lead emissions from site to site and the high degree of uncertainty resulting from an estimate based on only a very small sample of sites. As such, the primary contribution of this study is methodological, demonstrating how information from multiple sites can be combined and considered simultaneously for the estimation of fugitive emission rates, but recognizing that additional sites must be included to obtain a more precise characterization.

Air Pollutants↗
PubMed2004

Quantitative information on pore size distribution from the tangents of comparison plots.

The comparison plot obtained from the nitrogen adsorption data has a similar shape to that of the curve of accumulating pore volume of a solid. The intrinsic nature of this relation is discussed. It is known that the derivatives of the accumulating pore volume with respect to the pore size are the pore size distribution (PSD) of the solid. Thus, the tangent curve of the comparison plot can display, at least qualitatively, the PSD of a solid, over a wide range of pore sizes (from approximately 1 to 50 nm) because the comparison plot is applicable to both micropores and mesopores. Quantitative pore structure information can be derived from the comparison plots by establishing a relationship between the t value and the pore size from the samples with uniform pore structure and known pore sizes, such as MCM-41 and alumina pillared clay samples. A calculation procedure to derive quantitative PSD from the comparison plots is suggested, giving reasonable results. This study proposes concise and reliable methods based on the comparison plots to derive information on pore structure in porous solids.

Journal Article↗