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K M Wittkowski

Publications and source records attributed to K M Wittkowski.

6 recordsLinked to original sources
PubMed1991

A structured visual language for a knowledge-based front-end to statistical analysis systems in biomedical research.

Within the last few years, several knowledge-based systems for statistical analysis systems have been proposed (see Refs. 1-4 for references). Most of these systems provide so-called 'natural-language' interfaces for acquisition and application of meta-data. Since graphics have been very efficient in displaying results (e.g., as scatter, QQ and residual plots), some attempts have been made (cf. Refs. 5,6) to use graphics also to display knowledge of the statistical strategy. In the present paper I will concentrate on the visualization of knowledge of the experimental design and its impacts on the design of a structured visual syntax language for acquisition and application of this knowledge in the field of biomedical research.

Artificial Intelligence↗
PubMed1990

[Time order error and position effect of a standardized stimulus in discrimination of short time duration].

In comparison judgments of two successively presented time intervals ranging from 30 to 70 msec a time-order error (TOE) as well as a systematic effect depending on the constant position error (CPE) were demonstrated. The effects proved to be independent. Contrary to Vierordt's law, a negative TOE was found. When presenting the standard interval first, an increased hit rate resulting in a positive CPE was established. Furthermore, a test statistic is introduced that allows analysis of experiments utilizing all available information of a subject's psychometric function.

Adult↗
PubMed1989

Evaluation of seroepidemiological associations between HIV-infection, hepatitis B and other sexually transmitted diseases in African patients.

To assess the possible role of sexually transmitted diseases as cofactors for the spread of AIDS, 248 adult patients were tested for the presence of antibodies against human immunodeficiency virus (HIV), hepatitis B virus (HBV) and syphilis. The survey was conducted in a hospital at Kagondo, Kagera Region, Northwest Tanzania, Africa. Subjects were randomly chosen from the outpatient clinic to include those with and without sexually transmitted diseases, as well as AIDS/pre-AIDS patients. The data were univariately and multivariately analysed by linear logit models, including interactions of demographic parameters. The results obtained reveal a strong association between the presence of antibodies against HIV, syphilis and HBV, respectively. The HBV/HIV-correlation remained stable in the multivariate analysis including interactions of social parameters, in contrast to the syphilis/HIV-correlation. We assume that this reflects the lower virulence of HBV as compared to that of syphilis. The prevalence of anti-HBV antibodies seems to be a more reliable marker for high sexual activity than those against syphilis. The possibility that HBV and HIV act as cofactors for each other's transmission could not be ruled out.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Preventing the heterosexual spread of AIDS: what is the best advice if compliance is taken into account?

It has been recently advocated that avoiding partners who may be at high risk of carrying HIV provides 5000-fold better protection against HIV infection than usage of condoms [1]. In this paper, it is demonstrated that this guideline is largely based on unrealistic assumptions. If the sensitivity of identifying high-risk partners, realistic estimates of the efficiency of mechanical and chemical barrier methods, and the compliance in following either strategy are taken into account, use of condoms and/or suppositories containing nonoxynol-9 might be more effective than the attempt to avoid high-risk partners. Thus, both barrier methods should be strongly recommended for casual sexual heterosexual contacts.

Acquired Immunodeficiency Syndrome↗
PubMed1988

[Complaints in the postoperative phase related to anesthetics].

In two prospective, randomized studies the frequency of headache, nausea, vomiting, and analgesic requirement during the first postoperative 24 h was observed in order to study differences between the sexes and the inhalation anesthetics halothane, enflurane, isoflurane, or balanced anesthesia with enflurane/alfentanil. Nausea and vomiting were more frequent after enflurane than after halothane or isoflurane. There was no significant difference between anesthetics and frequency of headache, but there were significant differences in postoperative analgesic requirements which were highest after halothane and lowest after isoflurane. Postoperative complaints were always significantly greater among women than among men. The second study indicated that balanced anesthesia did not reduce the analgesic requirement compared to enflurane without alfentanil, but lead to a higher incidence of vomiting. After premedication with flunitrazepam and atropine and combined with 70% N2O/30% O2, isoflurane was the most favorable anesthetic agent with regard to the parameters studied. Balanced anesthesia with enflurane/alfentanil did not show any advantages for patients in the postoperative phase under the given conditions.

Adolescent↗