New Parameterization in Muon Decay and the Type of Emitted Neutrino

Normal muon decay, $\mu^{+} \to e^{+}\nu_{e}\bar{\nu_{\mu}}$, is studied as a tool to discriminate between the Dirac and Majorana types of neutrinos and to survey the structure of the weak interaction. It is assumed that massive neutrinos mix with one another and that the interaction Hamiltonian consists of the $V-A$ and $V+A$ charged currents. A new set of parameters used in place of the Michel parameters is proposed for the positron distribution. Explicit forms of these new parameters are obtained by assuming that the masses are less than 10 eV for light neutrinos and sufficiently large for heavy Majorana neutrinos, which are not emitted in the muon decay. It is shown that a possible method to discriminate between the Dirac and Majorana cases is to use a characterization given by the $\chi^2$ fitting of their spectra. It is also confirmed that the theoretical predictions in the Majorana neutrino case are almost the same as those obtained from the standard model. Indeed, their differences cannot be distinguished within the present experimental precision.Comment: 30 page

Nutrition and Depressive Symptoms in Community-dwelling Elderly Persons in Japan

A cross-sectional study was conducted to evaluate the association between dietary intake and depressivesymptoms in community-dwelling elderly persons. Five-hundred elderly persons aged 65 to 75 years were randomly selected from the population of O city in Okayama Prefecture, Japan. Among 401 respondents (response rate, 80.0%), data from 279 (133 males, 146 females) who completed the questionnaire concerning dietary intake and depressive state were analyzed using logistic regression. Each of 17 dietary intakes was classified into tertiles:high intake, moderate intake, and low intake. The Center for Epidemiology Studies Depression scale (CES-D) was used. Among males, the observed odds ratios (the 95% confidence intervals) for the depressive state were 0.36 (95% CI:0.13-0.98) in the highest tertile of carotene intake, 0.33 (95% CI:0.12-0.93) in the highest tertile of vitamin C intake, 0.29 (95% CI:0.10-0.85) in the highest tertile of carbohydrate intake, and 0.33 (95% CI:0.12-0.92) in the medium tertile of vitamin E intake. Among females, similar results were observed, but these results were not statistically significant. The results suggested that carbohydrate, carotene, and vitaminC intakes are associated with lowering depressive symptoms among elderly persons dwelling in communities in Japan.</p

Early childhood exposure to maternal smoking and Kawasaki Disease: A longitudinal survey in Japan

Kawasaki disease is the leading cause of acquired childhood heart disease in most developed countries, but the etiology of the disease is unknown. An aberrant immune response to some environmental triggers may play a role and involuntary exposure to tobacco smoke can alter immune functions. We thus prospectively examined the association between early childhood exposure to maternal smoking and the incidence of Kawasaki disease. We used a large, nationwide population-based longitudinal survey ongoing since 2010 and restricted participants to a total of 38,444 children for whom information on maternal smoking was available. Maternal smoking status was ascertained at 6months of age, and responses to questions about hospital admission for Kawasaki disease between the ages of 6 and 30months were used as outcome. We conducted binomial log-linear regression analyses adjusting for children's, parental, and residential factors with children of non-smoking mothers as our reference group. Maternal smoking increased the risk of admission, in particular for the period between 6 and 18months of age, in a dose-dependent manner. Compared with children of non-smoking mothers, the children of mothers who smoked had a risk ratio of 1.83 (95% confidence interval: 1.06, 3.35) for hospital admissions between 6 and 30months of age and a risk ratio of 2.69 (95% confidence interval: 1.56, 4.64) for hospital admissions between 6 and 18months of age. Early childhood exposure to maternal smoking may increase the risk of Kawasaki disease hospitalizations in childhood

Simulations on Prevalence of Echinococcus multilocularis in Hokkaido on the Basis of Vole Population Dynamics

In our study, we have investigated the influence of the intermediate host population density on the prevalence of Echinococcus multilocularis in the definitive host using a mathematical model of transmission. For the vole population (intermediate host) in Hokkaido, a model of population dynamics has been constructed in this paper which follows the seasonal and annual fluctuations. In the northeastern area, the vole density appears to fluctuate periodically with a 4 year cycle. The prevalence of Echinococcus multilocularis in the fox population (definitive host) can be affected by the density of vole through the fox ingesting infectious voles. Therefore we have prepared a food habit function of foxes and the logistic distribution has been proposed. The simulations which have been carried out using the mathematical model for transmission of Echinococcus multilocularis together with the vole dynamics have indicated that the prevalence in foxes is correlated and synchronized with the population dynamics of vole. In addition they have also made us recognize that it is necessary to introduce a suitable food habit function into the transmission model

Trends in Geographic Distribution of Nursing Staff in Japan from 2000 to 2010:A Multilevel Analysis

The aim of this study was to examine trends in the geographic distribution of nursing staff in Japan from 2000 to 2010. We examined time trends in the rates of nursing staff per 100,000 population across 349 secondary health service areas. Using the Gini coefficient as a measure of inequality, we separately analyzed the data of 4 nursing staff types:public health nurses (PHN), midwives (MW), nurses (NS), and associate nurses (AN). Then, using multilevel Poisson regression models, we calculated the rate ratios (RRs) and their 95% confidence intervals (CIs) for each type of nursing staff per 1-year change. Overall, the distribution of PHN, MW, and NS improved slightly in terms of the Gini coefficient. After adjusting for prefectural capital and population density, PHN, MW, and NS significantly increased;the RRs per 1-year increment were 1.022 (95% CI:1.020-1.023), 1.021 (95% CI:1.019-1.022), and 1.037 (95% CI:1.037-1.038), respectively. In contrast, AN significantly decreased;the RR per 1-year increment was 0.993 (95% CI:0.993-0.994). Despite the considerable increase in the absolute number of nursing staff in Japan (excluding AN), this increase did not lead to a sufficient improvement in distribution over the last decade

Risk Factors for Nosocomial Infection in the Neonatal Intensive Care Unit by the Japanese Nosocomial Infection Surveillance (JANIS)

We evaluated the infection risks in the neonatal intensive care unit (NICU) using data of NICU infection surveillance data. The subjects were 871 NICU babies, consisting of 465 boys and 406 girls, who were cared for between June 2002 and January 2003 in 7 medical institutions that employed NICU infection surveillance. Infections were defined according to the National Nosocomial Infection Surveillance (NNIS) System. Of the 58 babies with nosocomial infections, 15 had methicillin-resistant Staphylococcus aureus (MRSA) infection. Multiple logistic regression analysis demonstrated that the odds ratio for nosocomial infections was significantly related to gender, birth weight and the insertion of a central venous catheter (CVC). When the birth weight group of more than 1, 500g was regarded as the reference, the odds ratio was 2.35 in the birth weight group of 1,000-1,499g and 8.82 in the birth weight group of less than 1,000g. The odds ratio of the CVC () for nosocomial infection was 2.27. However, other devices including artificial ventilation, umbilical artery catheter, umbilical venous catheter, and urinary catheter were not significant risk factors. The incidence of MRSA infection rapidly increased from 0.3% in the birth weight group of more than 1,500g to 2.1% in the birth weight group of 1,000-1,499g, and to 11.1% in the birth weight group of less than 1,000g. When the birth weight group of more than 1,500g was regarded as the reference, multiple logistic regression analysis demonstrated that the odds ratio was 7.25 in the birth weight group of 1,000-1,499g and 42.88 in the birth weight group of less than 1,000g. These odds ratios were significantly higher than that in the reference group. However, the application of devices did not cause any significant differences in the odds ratio for MRSA infection.</p