Flickering flash signals and mate recognition in the Asian firefly, Aquatica lateralis.

Nocturnal fireflies sometimes use intricate bioluminescent signal systems for sexual communication. In this study, we examined flash signals and mate recognition in the Asian firefly, Aquatica lateralis, under natural field conditions. We found that the flash pattern of females changes after copulation, from simple short flashes to flashes with longer duration and flickering. To understand the functions of flickering, we video-recorded and analyzed the flashes of sedentary males, receptive females, and mated females. The results showed that the flashes of these three adult phases can be discriminated from each other by two parameters, flash duration and flicker intensity, with little overlap. Male attraction experiments using an artificial LED device termed 'e-firefly' confirmed that flying and sedentary males are attracted to flashes with shorter durations and lower flicker intensities. The range of attraction success was much wider for flying males and narrower for sedentary males, and the latter was close to the range of receptive female's flashes. These findings suggest that in addition to flash duration, flicker intensity is a flash signal parameter of mate recognition in A. lateralis males.

Exposure to PM2.5 and Lung Function Growth in Pre- and Early-Adolescent Schoolchildren: A Longitudinal Study Involving Repeated Lung Function Measurements in Japan.

Rationale: Epidemiological evidence indicates that ambient exposure to particulate matter ⩽2.5 µm in aerodynamic diameter (PM2.5) has adverse effects on lung function growth in children, but it is not actually clear whether exposure to low-level PM2.5 results in long-term decrements in lung function growth in pre- to early-adolescent schoolchildren. Objectives: To examine long-term effects of PM2.5 within the 4-year average concentration range of 10-19 µg/m3 on lung function growth with repeated measurements of lung function tests. Methods: Longitudinal analysis of 6,233 lung function measurements in 1,466 participants aged 8-12 years from 16 school communities in 10 cities around Japan, covering a broad area of the country to represent concentration ranges of PM2.5, was done with a multilevel linear regression model. Forced expiratory volume in 1 second, forced vital capacity (FVC), and maximal expiratory flow at 50% of FVC were used as lung function indicators to examine the effects of 10-µg/m3 increases in the PM2.5 concentration on relative growth per each 10-cm increase in height. Results: The overall annual mean PM2.5 level was 13.5 µg/m3 (range, 10.4-19.0 µg/m3). We found no association between any of the lung function growth indicators and increases in PM2.5 levels in children of either sex, even after controlling for potential confounders. Analysis with two-pollutant models with O3 or NO2 did not change the null results. Conclusions: This nationwide longitudinal study suggests that concurrent, long-term exposure to PM2.5 at concentrations ranging from 10.4 to 19.0 µg/m3 has little effect on lung function growth in preadolescent boys or pre- to early-adolescent girls.

Anticipatory postural adjustments contribute to age-related changes in compensatory steps associated with unilateral perturbations.

Compensatory steps are essential for preventing falls following perturbations. This study aimed to explore age-related changes in compensatory steps to unilateral perturbations, specifically in terms of whether anticipatory postural adjustments (APAs) play a role in stabilizing lateral balance. Five young and five elderly male adults participated. The split-belt treadmill was used to provide bi- and unilateral perturbations, as forward or backward transitions, applied 10 times in random order. Backward steps evoked by unilateral forward perturbations were evaluated. We measured temporal characteristics, mediolateral (ML) center of mass (COM) motion, and ML step length of compensatory steps. Compensatory steps to unexpected perturbations showed delayed onset of foot-off (FO) and expanded lateral swing length in elderly compared to young subjects. Differences in COM motions and step width arose related to APAs. Elderly subjects showing APAs exhibited no significant differences in ML COM, ML COM velocity, or ML swing length compared to young subjects. However, elderly subjects without APAs showed significant changes toward instability in these parameters. The fact that APAs play a notable role, particularly in the elderly, in stability offers a new insight into preventing falls. However, APAs occurred in 29% of the steps of young and 35% of the steps of elderly subjects. If the occurrence of APAs in elderly people in response to compensatory steps was more frequent, fall risk would be reduced. Further studies, particularly into APA frequency, might contribute to improved intervention to prevent falls.

Robust extraction of local structures by the minimum beta-divergence method.

This paper discusses a new highly robust learning algorithm for exploring local principal component analysis (PCA) structures in which an observed data follow one of several heterogeneous PCA models. The proposed method is formulated by minimizing beta-divergence. It searches a local PCA structure based on an initial location of the shifting parameter and a value for the tuning parameter beta. If the initial choice of the shifting parameter belongs to a data cluster, then the proposed method detects the local PCA structure of that data cluster, ignoring data in other clusters as outliers. We discuss the selection procedures for the tuning parameter beta and the initial value of the shifting parameter mu in this article. We demonstrate the performance of the proposed method by simulation. Finally, we compare the proposed method with a method based on a finite mixture model.