We found a significant association between the serum concentration of trace elements and breast cancer.

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The reduction of road crashes and injuries among motorcyclists in Nigeria requires a system inquiry into some safety issues at pre-crash, crash and post-crash stages to guide action plans. This paper examines safety issues such as age restriction, motorcycle engine capacity, highway code awareness, licence holding, helmet usage, crash involvement, rescue and payment for treatment among commercial motorcyclists. The primary data derived from a structured questionnaire administered to 334 commercial motorcyclists in Samaru, Zaria were analysed using descriptive statistics and logistic regression technique. There was total compliance with age restriction and motorcycle engine capacity. About 41.8% of the operators were not aware of the existence of the highway code. The odds of licence holding increased with highway code awareness, education with above senior secondary as the reference category and earnings. The odds of crash involvement decreased with highway code awareness, earnings and mode of operation. About 84% of the motorcyclists did not use crash helmet, in spite of being aware of the benefit, and 65.4% of motorcycle crashes was found to be with other road users. The promotion of safety among motorcyclists therefore requires strict traffic law enforcement and modification of road design to segregate traffic and protect pedestrians.

A family of exponential-type estimator for estimating population mean in two-phase sampling when the population proportion of the auxiliary character is available is proposed in this paper. Theoretically, the bias and minimum mean square error (MSE) for the proposed estimator are obtained. The expression for MSE of the proposed exponential-type of estimator is compared with the existing estimators in the literature. The optimum values of the parameters are determined. An empirical study was carried out by comparing the proposed estimators with some of the existing estimators reviewed in the literature based on the criteria of bias, mean square error (MSE) and relative efficiency using life datasets. The result of the comparisons showed that the proposed exponential-type estimators produce a better estimate of finite population mean than the existing estimators in the sense of having higher percentage relative efficiency which implies lesser mean square error and bias. Furthermore, the realistic conditions under which the proposed class of exponential-type estimators is more efficient were also presented. Thus, the proposed estimators can be considered as significant alternatives to estimating population characteristics of real life datasets.

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