How “Dependent” Are We? A Spatiotemporal Analysis of the Young and the Older Adult Populations in the US

The shifting of a country’s age structure has far-reaching socioeconomic and policy implications. In the US, the changing age structure at the sub-national level has received little research attention. To address this gap, we examine age dependencies across states in the US between 1990 and 2010 using decennial census data. We find that dependency changes have been gradual with a distinct graying of states during this period. Within this overarching trend, the sources of states’ dependencies follow complicated trajectories without clear spatiotemporal patterns. Nevertheless, changes in states’ old-age dependency contributions to respective total dependencies are geographically clustered and the inverse link between old-age dependency and economic productivity across states may be waning. Additional research is justified to further unravel these trends in old-age dependencies. The analytic framework that we apply can be adopted to conduct sub-national age dependency studies for other countries, including some European nations with relatively large proportions of older adults and many developing nations with an increasing share of older adults

Changing Age Segregation in the US: 1990 to 2010

Age segregation adversely impacts health and wellbeing. Prior studies, although limited, report increasing age segregation of the US. However, these studies are dated, do not comprehensively examine the spatiotemporal patterns and the correlates of intergenerational segregation, or suffer from methodological limitations. To address these gaps, we assess the spatiotemporal patterns of age segregation between 1990 and 2010 using census-tract data to compute the dissimilarity index (D) at the national, state, and county levels. Results contradict previous findings providing robust evidence of decreasing age segregation for most parts of the country and across geographical levels. We also examine factors explaining adult-older adult segregation across counties between 1990 and 2010. Higher levels of rurality indicated lower levels of adult-older adult segregation but this association diminished over time. Percent of older adults and percent of population in group quarters were inversely related to adult-older adult segregation, contrary to results from previous decades

Age-Race-Ethnicity Segregation in the United States: Where do Minority Older Adults Stand?

A recent study shows that among the three age groups of youth, adult and older adult, youth-older adult has the highest age segregation while youth-adult has the lowest. Similar to many previous age segregation studies, racial-ethnic differences, an important population axis in segregation studies, were not considered. Prior studies are also limited to using two-group measures, failing to compare multiple groups together. We explore the complexity in measuring intersectional segregation focusing on the two axes of age and race-ethnicity and propose a conditional approach to measure age segregation by racial-ethnic groups, and racial-ethnic segregation by age groups. Using this approach, we empirically study the 2010 age-race-ethnic segregation at the county and state levels in the United States, using census tracts as the basic units. Both the two and multigroup dissimilarity indices were used. Results show that the racial-ethnic axis had been a stronger force in segregation than the age axis. Results also show disparities of racial-ethnic segregation across age groups with the highest levels present among older adults and in urban counties. For all three age groups, segregation levels involving Natives and Asians tend to be higher than those without them. In contrast, age segregation was the highest between youths and older adults, and the levels varied across racial-ethnic groups with Natives at the highest levels. Although age segregation was significantly different between urban and rural counties, higher segregation in urban areas were mostly involving Whites as opposed to higher segregation in rural counties involving minority racial groups. Studying age segregation should not be colour blinded, as nonwhite older adults in rural counties were more likely to experience higher levels of age segregation than other groups

No More “Social Distancing” But Practice Physical Separation

Though not a new term, “social distancing” exploded onto the global stage as an expression to publicize the only means currently available to control the transmission of COVID-19. This term is increasingly being adopted and translated into the vernacular to inform and guide public behavior in most, if not all, countries around the world. However, any effective global response requires direct and unambiguous communication and sharing of ideas across communities with different cultural backgrounds as well as between researchers and responders across the disciplinary spectrum. Unfortunately, social distancing is a misnomer. The current use of social distancing – separating ourselves physically to avoid infection – is not consistent with what the term actually means. Consequently, as a diktat, social distancing is not self-explanatory, conceptually ambiguous, practically misleading, and intellectually misplaced. To highlight these problems, we present arguments from multiple perspectives, calling governments, public health officials, and the media to abandon the use of social distancing, replacing it with more intuitively accurate and meaningful terms. Such a move would ensure clear consistent messaging that is critical to retain public trust especially during global public health crises

An engineered cardiac reporter cell line identifies human embryonic stem cell-derived myocardial precursors.

Unlike some organs, the heart is unable to repair itself after injury. Human embryonic stem cells (hESCs) grow and divide indefinitely while maintaining the potential to develop into many tissues of the body. As such, they provide an unprecedented opportunity to treat human diseases characterized by tissue loss. We have identified early myocardial precursors derived from hESCs (hMPs) using an α-myosin heavy chain (αMHC)-GFP reporter line. We have demonstrated by immunocytochemistry and quantitative real-time PCR (qPCR) that reporter activation is restricted to hESC-derived cardiomyocytes (CMs) differentiated in vitro, and that hMPs give rise exclusively to muscle in an in vivo teratoma formation assay. We also demonstrate that the reporter does not interfere with hESC genomic stability. Importantly, we show that hMPs give rise to atrial, ventricular and specialized conduction CM subtypes by qPCR and microelectrode array analysis. Expression profiling of hMPs over the course of differentiation implicate Wnt and transforming growth factor-β signaling pathways in CM development. The identification of hMPs using this αMHC-GFP reporter line will provide important insight into the pathways regulating human myocardial development, and may provide a novel therapeutic reagent for the treatment of cardiac disease

Grain Physics and Rosseland Mean Opacities

Tables of mean opacities are often used to compute the transfer of radiation in a variety of astrophysical simulations from stellar evolution models to proto-planetary disks. Often tables, such as Ferguson et al. (2005), are computed with a predetermined set of physical assumptions that may or may not be valid for a specific application. This paper explores the effects of several assumptions of grain physics on the Rosseland mean opacity in an oxygen rich environment. We find that changing the distribution of grain sizes, either the power-law exponent or the shape of the distribution, has a marginal effect on the total mean opacity. We also explore the difference in the mean opacity between solid homogenous grains and grains that are porous or conglomorations of several species. Changing the amount of grain opacity included in the mean by assuming a grain-to-gas ratio significantly affects the mean opacity, but in a predictable way.Comment: 19 pages, 6 figures, accepted for publication in Ap

Fluctuations in the Site Disordered Traveling Salesman Problem

We extend a previous statistical mechanical treatment of the traveling salesman problem by defining a discrete "site disordered'' problem in which fluctuations about saddle points can be computed. The results clarify the basis of our original treatment, and illuminate but do not resolve the difficulties of taking the zero temperature limit to obtain minimal path lengths.Comment: 17 pages, 3 eps figures, revte

A New Approach toward Transition State Spectroscopy

Chirped-Pulse millimetre-Wave (CPmmW) rotational spectroscopy provides a new class of information about photolysis transition state(s). Measured intensities in rotational spectra determine species-isomer-vibrational populations, provided that rotational populations can be thermalized. The formation and detection of S0 vinylidene is discussed in the limits of low and high initial rotational excitation. CPmmW spectra of 193 nm photolysis of Vinyl Cyanide (Acrylonitrile) contain J=0-1 transitions in more than 20 vibrational levels of HCN, HNC, but no transitions in vinylidene or highly excited local-bender vibrational levels of acetylene. Reasons for the non-observation of the vinylidene co-product of HCN are discussed.Comment: Accepted by Faraday Discussion

Constant Size Molecular Descriptors For Use With Machine Learning

A set of molecular descriptors whose length is independent of molecular size is developed for machine learning models that target thermodynamic and electronic properties of molecules. These features are evaluated by monitoring performance of kernel ridge regression models on well-studied data sets of small organic molecules. The features include connectivity counts, which require only the bonding pattern of the molecule, and encoded distances, which summarize distances between both bonded and non-bonded atoms and so require the full molecular geometry. In addition to having constant size, these features summarize information regarding the local environment of atoms and bonds, such that models can take advantage of similarities resulting from the presence of similar chemical fragments across molecules. Combining these two types of features leads to models whose performance is comparable to or better than the current state of the art. The features introduced here have the advantage of leading to models that may be trained on smaller molecules and then used successfully on larger molecules.Comment: 18 pages, 5 figure