Phase Lags in the Optical-Infrared Light Curves of AGB Stars

To search for phase lags in the optical-infrared light curves of asymptotic giant branch stars, we have compared infrared data from the COBE DIRBE satellite with optical light curves from the AAVSO and other sources. We found 17 examples of phase lags in the time of maximum in the infrared vs. that in the optical, and 4 stars with no observed lags. There is a clear difference between the Mira variables and the semi-regulars in the sample, with the maximum in the optical preceding that in the near-infrared in the Miras, while in most of the semi-regulars no lags are observed. Comparison to published theoretical models indicates that the phase lags in the Miras are due to strong titanium oxide absorption in the visual at stellar maximum, and suggests that Miras pulsate in the fundamental mode, while at least some semi-regulars are first overtone pulsators. There is a clear optical-near-infrared phase lag in the carbon-rich Mira V CrB; this is likely due to C2 and CN absorption variations in the optical.Comment: AJ, in pres

Teaching speaking in the foreign language classroom

One of the most necessary skills for living in the twenty-first century is gaining the ability to know and use another language. In many areas of life, from business transactions to broadcasting television weather warnings, the demand for proficiency in a foreign language is growing. One of the most important skills to have in a foreign language is the ability to speak the language with native or non-native speakers of that language. A great number of foreign language learners most likely consider one of their primary language goals to be the ability to speak the language at a high level of proficiency. Thus, oral proficiency has become an important focus in the foreign language classroom

Evolutionary Physiology: The extent of C4 and CAM photosynthesis in the Genera Anacampseros and Grahamia of the Portulacaceae

The Portulacaceae is one of the few terrestrial plant families known to have both C(4) and Crassulacean acid metabolism (CAM) species. There may be multiple origins of the evolution of CAM within the Portulacaceae but the only clear evidence of C(4) photosynthesis is found in members of the genus Portulaca. In the Portulaca, CAM succulent tissue is overlaid with the C(4) tissue in a unique fashion where both pathways are operating simultaneously. Earlier reports have shown that the clade containing the genera Anacampseros and Grahamia may also contain C(4) photosynthetic species similar to the Portulaca, which would indicate multiple origins of C(4) photosynthesis within the family. The aim of the present study was to ascertain the true photosynthetic nature of these genera. An initial survey of the carbon isotope composition of the Anacampseros ranged from -12.6 per thousand to -24.0 per thousand, indicating very little CAM activity in some species, with other values close to the C(4) range. Anacampseros (=Grahamia) australiana which had been previously identified as a C(4) species had a carbon isotope composition value of -24.0 per thousand, which is more indicative of a C(3) species with a slight contribution of CAM activity. Other Anacampseros species with C(4)-like values have been shown to be CAM plants. The initial isotope analysis of the Grahamia species gave values in the range of -27.1 per thousand to -23.6 per thousand, placing the Grahamia species well towards the C(3) photosynthetic range. Further physiological studies indicated increased night-time CO(2) uptake with imposition of water stress, associated with a large diurnal acid fluctuation and a marked increased phosphoenolpyruvate carboxylase activity. This showed that the Grahamia species are actually facultative CAM plants despite their C(3)-like carbon isotope values. The results indicate that the Grahamia and Anacampseros species do not utilize the C(4) photosynthetic pathway. This is the first to identify that the Grahamia species are facultative CAM plants where CAM can be induced by water stress. This work supports earlier physiological work that indicates that this clade containing Anacampseros and Grahamia species comprises predominantly facultative CAM plants. This report suggests there may be only one clade which contains C(4) photosynthetic members with CAM-like characteristics

Comprehensive simulations of superhumps

(Abridged) We use 3D SPH calculations with higher resolution, as well as with more realistic viscosity and sound-speed prescriptions than previous work to examine the eccentric instability which underlies the superhump phenomenon in semi-detached binaries. We illustrate the importance of the two-armed spiral mode in the generation of superhumps. Differential motions in the fluid disc cause converging flows which lead to strong spiral shocks once each superhump cycle. The dissipation associated with these shocks powers the superhump. We compare 2D and 3D results, and conclude that 3D simulations are necessary to faithfully simulate the disc dynamics. We ran our simulations for unprecedented durations, so that an eccentric equilibrium is established except at high mass ratios where the growth rate of the instability is very low. Our improved simulations give a closer match to the observed relationship between superhump period excess and binary mass ratio than previous numerical work. The observed black hole X-ray transient superhumpers appear to have systematically lower disc precession rates than the cataclysmic variables. This could be due to higher disc temperatures and thicknesses. The modulation in total viscous dissipation on the superhump period is overwhelmingly from the region of the disc within the 3:1 resonance radius. As the eccentric instability develops, the viscous torques are enhanced, and the disc consequently adjusts to a new equilibrium state, as suggested in the thermal-tidal instability model. We quantify this enhancement in the viscosity, which is ~10 per cent for q=0.08. We characterise the eccentricity distributions in our accretion discs, and show that the entire body of the disc partakes in the eccentricity.Comment: 18 pages (mn2e LaTeX), 14 figures, 5 tables, Accepted for publication in MNRA

Age-Friendly Environments and Self-Rated Health: An Exploration of Detroit Elders

While a number of organizations and government entities have encouraged the development of more “age-friendly” environments, to date there has been limited research linking these environment features to elder outcomes. Using a representative sample of older adults living in Detroit, this study examined the association between age-friendly environment factors and self-rated health. Results indicated that access to health care, social support, and community engagement were each associated with better self-rated health, while neighborhood problems were associated with poorer self-rated health. Moreover, individual-level income and education no longer predicted self-rated health once age-friendly environment factors were taken into account. These findings highlight the need for more research documenting the effects of age-friendly environments, particularly across diverse contexts and populations

Do Age-Friendly Characteristics Influence the Expectation to Age in Place? A Comparison of Low-Income and Higher Income Detroit Elders

Currently there is limited evidence linking age-friendly characteristics to outcomes in elders. Using a representative sample of 1,376 adults aged 60 and older living in Detroit, this study examined the association between age-friendly social and physical environmental characteristics and the expectation to age in place, and the potential differences between low- and higher-income elders. Based on U.S. Environmental Protection Agency’s (EPA) age-friendly guide, we identified six factors reflecting age-friendly characteristics. Logistic regression models indicated that regardless of income level only neighborhood problems were significantly associated with expecting to age in place. Low-income elders were more likely to expect to age in place than their higher-income counterparts, and it is unclear whether this resulted from a desire to remain in the home or that there is no place else to go. Future research should address the ways in which financial resources affect the choices, expectations, and outcomes of aging in place

Conceptualizing age-friendly community characteristics in a sample of urban elders: An exploratory factor analysis

Accurate conceptualization and measurement of age-friendly community characteristics would help to reduce barriers to documenting the effects on elders of interventions to create such communities. This article contributes to the measurement of age-friendly communities through an exploratory factor analysis of items reflecting an existing U.S. Environmental Protection Agency policy framework. From a sample of urban elders (n =1,376), we identified six factors associated with demographic and health characteristics: Access to Business and Leisure, Social Interaction, Access to Health Care, Neighborhood Problems, Social Support, and Community Engagement. Future research should explore the effects of these factors across contexts and populations