Symmetry of Lyapunov exponents in bifurcation structures of one-dimensional maps.

We observe a symmetry of Lyapunov exponents in bifurcation structures of one-dimensional maps in which there exists a pair of parameter values in a dynamical system such that two dynamical systems with these paired parameter values have the same Lyapunov exponent. We show that this is a consequence of the presence of an invariant transformation from a dynamical system with one of the two paired parameter values to that with another parameter value, which does not change natures of dynamical systems.

Crystal structure of the catalytic domain of a GH16 ß-agarase from a deep-sea bacterium, Microbulbifer thermotolerans JAMB-A94.

A deep-sea bacterium, Microbulbifer thermotolerans JAMB-A94, has a ß-agarase (MtAgaA) belonging to the glycoside hydrolase family (GH) 16. The optimal temperature of this bacterium for growth is 43-49 °C, and MtAgaA is stable at 60 °C, which is one of the most thermostable enzymes among GH16 ß-agarases. Here, we determined the catalytic domain structure of MtAgaA. MtAgaA consists of a ß-jelly roll fold, as observed in other GH16 enzymes. The structure of MtAgaA was most similar to two ß-agarases from Zobellia galactanivorans, ZgAgaA, and ZgAgaB. Although the catalytic cleft structure of MtAgaA was similar to ZgAgaA and ZgAgaB, residues at subsite -4 of MtAgaA were not conserved between them. Also, an α-helix, designated as α4', was uniquely located near the catalytic cleft of MtAgaA. A comparison of the structures of the three enzymes suggested that multiple factors, including increased numbers of arginine and proline residues, could contribute to the thermostability of MtAgaA.

Thalassospira alkalitolerans sp. nov. and Thalassospira mesophila sp. nov., isolated from a decaying bamboo sunken in the marine environment, and emended description of the genus Thalassospira.

Two marine bacteria, designated strains MBE#61(T) and MBE#74(T), were isolated from a piece of sunken bamboo in the marine environment in Japan. Both of these strains were Gram-stain-negative, but had different cell shapes: MBE#61(T) was spiral, whereas MBE#74(T) was rod-shaped. The temperature, pH and salt concentration ranges for growth of strain MBE#61(T) were 4-38 °C (optimal at 32 °C), pH 4.5-11.0 (optimal at pH 7.0-8.0) and 1-11 % (optimal at 2 %) NaCl, whereas those of strain MBE#74(T) were 4-36 °C (optimal at 30 °C), pH 4.0-10.5 (optimal at pH 7.0-8.0) and 1-12 % (optimal at 4 %) NaCl. Phylogenetic analysis based on partial 16S rRNA gene sequences revealed that both strains belong to the genus Thalassospira within the class Alphaproteobacteria. Similarity between the 16S rRNA gene sequence of strain MBE#61(T) and those of the type strains of species of the genus Thalassospira was 97.5-99.0 %, and that of strain MBE#74(T) was 96.9-98.6 %; these two isolates were most closely related to Thalassospira lucentensis QMT2(T). However, the DNA-DNA hybridization values between T. lucentensis QMT2(T) and strain MBE#61(T) or MBE#74(T) were only 16.0 % and 7.1 %, respectively. The DNA G+C content of strain MBE#61(T) was 54.4 mol%, and that of strain MBE#74(T) was 55.9 mol%. The predominant isoprenoid quinone of the two strains was Q-10 (MBE#61(T), 97.3 %; MBE#74(T), 93.5 %). The major cellular fatty acids of strain MBE#61(T) were C18 : 1ω7c (31.1 %), summed feature 3 comprising C16 : 0ω7c/iso-C15 : 0 2-OH (26.1 %) and C16 : 0 (20.9 %); those of strain MBE#74(T) were C16 : 0 (26.2 %), C17 : 0 cyclo (19.9 %) and C18 : 1ω7c (12.1 %). On the basis of these results, strain MBE#61(T) and strain MBE#74(T) are considered to represent novel species of the genus Thalassospira, for which names Thalassospira alkalitolerans sp. nov. and Thalassospira mesophila sp. nov. are proposed. The type strains are MBE#61(T) ( = JCM 18968(T) = CECT 8273(T)) and MBE#74(T) ( = JCM 18969(T) = CECT 8274(T)), respectively. An emended description of the genus Thalassospira is also proposed.

Older Adults' Loneliness and Social Relationships in the Philippines: Comparison Between Rural and Urban Contexts.

This study compared patterns of association between social relationship measures and levels of loneliness for rural and urban older adults in the Philippines. We analyzed social relationship measures and loneliness scores (UCLA Three-Item Loneliness Scale) of a nationally representative sample of Filipino adults 60 years and older in the baseline survey of the 2018 Longitudinal Study of Ageing and Health in the Philippines (LSAHP) (n=4,704). The loneliness score was slightly higher for rural older adults (5.8) than for their urban counterparts (5.1; p=.0001). A significantly larger proportion of older adults in rural areas (12.7%) lived alone than in urban areas (5.4%; p=.0008). The overall pattern of association between social relationship measures and loneliness scores for the two groups was mostly similar. For both groups, living alone, having less active social involvement, and seeing friends less frequently were related to higher levels of loneliness. Poorer subjective financial well-being (e.g., the perception of considerable difficulty in making ends meet) was also significantly associated with higher loneliness scores. These findings suggest that the prevention of loneliness for older adults in countries in the early stages of population aging such as the Philippines requires a broad range of public health initiatives.

Japanese older adults' loneliness, family relationships and mortality: Does one's living arrangement make a difference?

AIM: This study examines how the association between older adults' family relationships and all-cause mortality differs among different household contexts: living alone, living with only a spouse and living with adult children. METHODS: We carried out a discrete-time event history analysis on all-cause mortality with measures of family relationships for each group of older adults. The study analyzed person-wave data from the Nihon University Japanese Longitudinal Study of Aging, including 11 225 longitudinal episodes between consecutive waves and 555 deaths reported in total. RESULTS: The family relationship measures were significantly associated with mortality only for older adults who resided with children. While providing support to children was negatively related to mortality, receiving support from children was positively associated with mortality. Feelings of loneliness were associated with higher mortality for older adults in intergenerational coresidence arrangements, but not for those in other living arrangements. CONCLUSION: The extent of support exchange between older adults and adult children tends to be associated with older adults' mortality only within the household context where parents and children live together. In other types of living arrangements (i.e. living alone and living with only a spouse), the association between family relationship measures and mortality is limited. Geriatr Gerontol Int 2019; ••: ••-••. Geriatr Gerontol Int 2020; 20: 156-160.

Intergenerational coresidence of older adults in Japan: conditions for cultural plasticity.

OBJECTIVES: This study investigated individual-level conditions and prefecture-level contextual factors that enable and/or restrict intergenerational coresidence arrangements between older parents and adult children. METHODS: We implemented multinomial logistic regression within a hierarchical approach to compare traditional and nontraditional styles of intergenerational coresidence arrangements. Individual data (N = 3,565) came from the Nihon University Japanese Longitudinal Study of Aging. We supplemented these with information on socioeconomic and welfare characteristics of Japanese prefectures. RESULTS: Whereas the traditional pattern of coresidence was primarily a value-driven arrangement, nontraditional coresidence was both a value-driven and a need-driven arrangement for older parents with limited physical abilities. Relatively strong economic conditions at the prefecture level were enabling factors for coresidence, whereas the greater per capita utilization of local welfare resources had both enabling and inhibiting effects on coresidence arrangements. DISCUSSION: The differences between the two types of coresidence are consistent with a shift of intergenerational living arrangements in Japan from a preventive arrangement to a contingent arrangement for older parents in need. We suggest that intergenerational family traditions contain a great amount of plasticity to accommodate societal modernization by adapting to the changing cultural and socioeconomic contexts of the society.

A longitudinal analysis of the impact of family support on the morale of older parents in Japan: does the parent's normative belief in filial responsibilities make a difference?

Japan presents a unique social laboratory in which to examine how family support impacts on older adults' psychological wellbeing. This is because of its cultural climate where distinctively different expectations of old-age independence and the traditional norm of filial piety coexist. This study investigated how structural and functional dimensions of the family support of older Japanese parents influence their psychological morale, and whether the impacts of family support on parents' morale vary depending on the parents' belief in the traditional cultural norm of filial piety. Four waves of data from the Nihon University Japanese Longitudinal Study of Aging (NUJLSOA) collected in 1999, 2001, 2003 and 2006 were analysed. Combining the two- or three-year span of longitudinal data between each wave (N=3,882), an ordered logistic regression analysis was undertaken. The results reveal that although parents who were widowed or received emotional support from a child tended to report a lower level of morale, the negative influences of such support tended to be mitigated if the parent agreed with the traditional cultural norm of filial responsibilities. These results imply that the meaning and benefit of family support may differ depending on the degree to which Japanese older parents support the traditional norm of filial responsibilities.

Purchasing piety? Coresidence of married children with their older parents in Japan.

We investigated the conditions under which married children live with their older parents in Japan. We focused on how needs and resources in each generation are associated with whether married couples live with their parents in parent-headed and child-headed households, and we also investigated difference in power relations between older and younger generations and between children and their spouses. We analyzed a nationally representative sample of older parents (n = 3,853) and their married children (n = 8,601) from the 1999 Nihon University Japanese Longitudinal Study of Aging (NUJLSOA). Mutinomial regression revealed that married children with relatively affluent parents tended to live with them in parent-headed households and that married children with parents who are in relatively poor health or who are widowed tended to live with them in child-headed households. We also found that less-educated married children tended to live in the households of their higher-income parents, suggesting that parents may be "purchasing" traditional arrangements with less-affluent children. In addition, children with an educational advantage over their spouses were more likely to have parents living with them in child-headed coresident households. We conclude that traditional multigenerational coresidence has become a commodity negotiated within families based on relative resources and needs within and across generations.