Modelling heterogeneous space–time occurrences of earthquakes and its residual analysis

Summary. Earthquake intensities are modelled as a function of previous activity whose specific form is based on established empirical laws in seismology, but whose parameter values can vary from place to place. This model is used for characterizing regional features of seismic activities in and around Japan, and also for exploring regions where the actual seismicity rate systematically deviates from that of the modelled rate.     

A note on mixingale limit theorems and stable convergence in law

A gap in the proof of a non stationary mixingale invariance principle is identified and fixed by introducing a skipped subsampling of a partial sum process and letting the skipped interval vanish asymptotically at an appropriate rate as the sample size increases. The corrected proof produces a mixingale limit theorem in the form of a mixing convergence in law, occurring jointly with the stable convergence in law for the same σ-field relative to which they are stable and mixing. The applicability of established results to a high-frequency estimation of the quadratic variation of financial price process is discussed.     

Influence of a home-based exercise program on the urine pH in elderly female subjects: a secondary analysis of a randomized controlled trial

Background

A low urine pH is a characteristic metabolic feature of metabolic syndrome and type 2 diabetes. The purpose of the current study was to investigate the effects of a 12-week home-based bench step exercise on the urine pH status of elderly female subjects.

Methods

The current study is a secondary analysis of a randomized controlled trial (RCT) in which 59 postmenopausal female subjects were randomized to either the exercise group (n?=?29) or the control group (n?=?30). The subjects in the exercise group were instructed to perform home-based exercises using a bench step at the anaerobic threshold (AT), with a goal of performing ≥140 min/week at home for 12 weeks. The subjects in the control group were instructed to not change their normal lifestyle. Urine was collected after overnight fasting, and the urine pH was measured using a urinary test strip. The inter-group-differences at baseline and the pre-post changes within groups were assessed using the Mann-Whitney U test and Wilcoxon’s signed-rank test, respectively. Additionally, the difference in the post-intervention urine pH levels of the two groups, adjusted for the pre-intervention values (the estimated effect size) and the precision (95% confidence intervals) were investigated using an analysis of covariance.

Results

The pre-post comparison of the urine pH data using Wilcoxon’s signed-rank test showed a significant increase in the urine pH levels of the exercise group (p?<?0.05); there was no significant change in the urine pH levels of the control group. However, the estimated effect size (0.15) was small and the confidence interval straddled 0 (?0.25–0.55).

Conclusions

Based on the results of the current secondary analysis of an RCT, we could not clearly conclude that exercise has a beneficial effect on the urine pH. Further well-designed RCTs should be conducted to determine whether aerobic exercise is truly able to ameliorate urine acidification.

Trial registration

The study was retrospectively registered in the University Hospital Medical Information Network (UMIN) as “Effect of step exercise on aerobic fitness and progression of atherosclerosis in the elderly” under the registration number UMIN 000026743 (the date of registration: March 28, 2017).

     

Exposure Assessment of Heavy Metals Resulting from Farmland Application of Wastewater Sludge in Tianjin, China: The Examination of Two Existing National Standards for Soil and Farmland-Used Sludge

Land application is one of the major methods of managing municipal sludge in China. The sludge is used for fertilizing and conditioning soil, but due to the high concentration of heavy metals and other chemicals that it contains, improper use of sludge will lead to the contamination of farmland soil. To provide guidance on the application of sludge in China, the Control Standards for Pollutants in Sludge for Agricultural Use (CSPSAU) were enacted, and implemented in 1985. Afterwards, the National Environment Quality Standards for Soil (NEQSS) were also formulated and put into effect in 1996. In this article, these two national standards were examined by means of exposure assessment. The main exposure pathway to humans that was considered was dietary intake of crops grown on the sludge-applied farmland. Five major types of agricultural crops (rice, wheat, tuber roots, vegetables, and fruits) and three groups of exposure population (the urban individual group, the rural sludge-applying individual group, and the rural sludge nonapplying individual group) were assessed. This case study in Tianjin, China, shows the necessity of reexamining the national standards of the CSPSAU and the NEQSS in the context of risk assessment. More comprehensive surveys and monitoring programs assessing heavy metals contained in farmland soils and crop tissues will be necessary for examining the risks to human health.     

Social capital online: Collective use of the Internet and reciprocity as lubricants of democracy

This article puts the democratic potential of using the Internet into perspective through an analysis of how collective uses of the Internet promote social capital. Research results reveal that social capital online (i.e. trust and reciprocity) is enhanced by involvement in collective use of the Internet such as participation in online communities and use of the Internet among informal groups in everyday life. This process could counter negative aspects of Internet use. Further, accumulated online social capital can be a powerful predictor of online political participation, i.e. online reciprocity has a positive effect on intention to participate in online civic discussion. Finally, the authors' analyses indicate the possibility of a spillover of online social capital into offline arenas. It is concluded that collective use of the Internet can be a lubricant for democracy.     

Two-Step Residual-Based Estimation of Error Variances for Generalized Least Squares in Split-Plot Experiments

In split-plot experiments, estimation of unknown parameters by generalized least squares (GLS), as opposed to ordinary least squares (OLS), is required, owing to the existence of whole- and subplot errors. However, estimating the error variances is often necessary for GLS. Restricted maximum likelihood (REML) is an established method for estimating the error variances, and its benefits have been highlighted in many previous studies. This article proposes a new two-step residual-based approach for estimating error variances. Results of numerical simulations indicate that the proposed method performs sufficiently well to be considered as a suitable alternative to REML.     

Contest and scramble competitions in two bruchid species,Callosobruchus analis andC. Phaseoli (Coleoptera: Bruchidae)

Summary We performed multiple-generation competition experiments betweenCallosobruchus analis andC. phaseoli with different bean sizes. In each system, we supplied 5 g of mung beans (Vigna radiata) every 10 days. We examined three types of bean conditions: 5 g of large beans, 5 g of small beans, and a mixture of 2.5 g of large and small beans. In small bean condition,C. analis dominatedC. phaseoli in all three replicates andC. phaseoli was extinct by the 260th day. On the contrary,C. phaseoli overcameC. analis within 250 days in large beans in all three replicates. In mixed beans condition the two bruchid species coexisted more than 500 days in two out of the three replicates. Even in the exceptional case, both species coexisted for 460 days. These results were examined in the light of the predictions from short-term larval competition experiments and a game theoretical model by Smith and Lessells (1985). The density and frequency dependent results during larval competition inside a bean was concluded to be a main factor to produce the above long-term competition results.