Biomedical subjects

M S Nikulin

Publications and source records attributed to M S Nikulin.

3 recordsLinked to original sources

PubMed2001

A probabilistic description of radioactive contamination: a multivariate model.

A multivariate discrete probability model is used to facilitate the description of gamma-ray spectroscopic data obtained from radioactively contaminated territory, east of the former Semipalatinsk nuclear test site in Kazakhstan. Two possible estimators of probabilities of interest have been considered: maximum likelihood and unbiased estimators. We show that unbiased estimators are much easier to compute. The model was used in two variants: (i) several radionuclides in spatially independent measurements, (ii) a single radionuclide in spatially dependent measurements. We show that, in both cases, it is important to take into account the correlation for the accurate evaluation of probabilities of interest.

Gamma Rays↗

PubMed2001

Estimation in degradation models with explanatory variables.

Influence of covariates on degradation is modelled. Models which include dependence of the intensity of the process of traumatic events on the degradation level are also discussed. Estimation of reliability and degradation characteristics from data with covariates is considered in dynamic environments.

Equipment Failure↗

PubMed1999

Generalized proportional hazards model based on modified partial likelihood.

The proportional hazards (Cox) model is generalized by assuming that at any moment the ratio of hazard rates is depending not only on values of covariates but also on resources used until this moment. Relations with generalized multiplicative, frailty and linear transformation models are considered. A modified partial likelihood function is proposed, and properties of the estimators are investigated.

Humans↗