A new look at Sco OB1 association with Gaia DR2

We present and discuss photometric optical data in the area of the OB association Sco OB1 covering about 1 squared degree. UBVI photometry is employed in tandem with Gaia DR2 data to investigate the 3 dimensional structure and the star formation history of the region. By combining parallaxes and proper motions we identify 7 physical groups located between the young open cluster NGC 6231 and the bright nebula IC4628. The most prominent group coincides with the sparse open cluster Trumpler 24. We confirm the presence of the intermediate age star cluster VdB-Hagen 202, which is unexpected in this environment, and provide for the first time estimates of its fundamental parameters. After assessing individual groups membership, we derive mean proper motion components, distances, and ages. The seven groups belong to two different families. To the younger family (family I) belong several pre-Main Sequence stars as well. These are evenly spread across the field, and also in front of VdB-Hagen 202. VdB-Hagen 202 and two smaller, slightly detached, groups of similar properties form family II, which do not belong to the association, but are caught in the act of passing through it. As for the younger population, this forms an arc-like structure from the bright nebula IC 4628 down to NGC 6231, as previously found. Moreover, the pre-Main Sequence stars density seems to increase from NGC 6231 northward to Trumpler 24

Power Couples: Changes in the Locational Choice of the College Educated, 1940-1990

The rise of the dual career household is a recent phenomenon spurred by the increase in married women's labor force participation rates and educational attainment rates. Compared to traditional households these households must solve a colocation problem. This paper documents trends in locational choice between large and small metropolitan areas and non-metropolitan areas by household type from 1940 to 1990. We find that college educated couples are increasingly concentrated in large metropolitan areas and attribute at least half of this increase to the growing severity of the colocation problem. We also find that the relative returns for a college-educated couple of being in a large relative to a small city have increased across decades. Our results suggest that because skilled professionals are increasingly bundled with an equally skilled spouse, smaller cities may experience reduced inflows of human capital relative to the past and therefore become poorer. We examine how the relationship between rankings of university graduate programs and city size has changed between 1970 and 1990 to provide suggestive evidence on the importance of city size to firms' ability to attract the best workers.

Shame and Ostracism: Union Army Deserters Leave Home

During the Civil War not all men served honorably and this was known by everyone in their communities. We study how shame and ostracism affect behavior by examining whether men who deserted from the Union Army, and who faced no legal sanctions once the war was over, returned home or whether they moved and re-invented themselves. We build a unique panel data set that provides us with a control group for deserters because we can identify men who deserted but then returned to fight with their companies. We find that, compared to non-deserters and returned deserters, deserters were more likely to move both out of state and further distances. This effect was stronger for deserters from pro-war communities. When deserters moved they were more likely to move to anti-war states than non-deserters. Our study provides a rare test of the empirical implications of emotion. While both shame and ostracism would push deserters out of their home community, we find no evidence that deserters faced economic sanctions.

Cowards and Heroes: Group Loyalty in the American Civil War

What motivated men to risk death in the most horrific war in U.S. history when pay was low and irregular and military punishment strategies were weak? In such a situation creating group loyalty by promoting social capital is of paramount importance and in the Civil War was the cement of both armies. We find that individual and company socio-economic and demographic characteristics, ideology, and morale were important predictors of group loyalty in the Union Army. Company characteristics were more important than ideology or morale. Soldiers in companies that were more homogeneous in ethnicity, occupation, and age were less likely to shirk.

Changes in the Value of Life: 1940-1980

We present the first nation wide value of life estimates for the United States at more than one point in time. Our estimates are for every ten years between 1940 and 1980, a period when declines in fatal accident rates were historically unprecedented. Our estimated elasticity of value of life with respect to per capita GNP is 1.5 to 1.7. We illustrate the importance of rising value of life for policy evaluation by examining the benefits of improved longevity since 1900, showing that the current marginal increase in longevity is more valuable than the large increase in the first half of the twentieth century.

Understanding the Decline in Social Capital, 1952-1998

We evaluate trends in social capital since 1952 and assess explanations for the observed declines. We examine both social capital centered in the community and in the home and argue that the decline in social capital has been over-stated. Controlling for education, there have been small declines in the probability of volunteering, larger declines in group membership, and still larger declines in the probability of entertaining since the 1970s. There have been no declines in the probability of spending frequent evenings with friends or relatives, but there have been decreases in daily visits with friends or relatives. Rising community heterogeneity (particularly income inequality) explains the fall in social capital produced outside the home whereas the rise in women's labor force participation rates explains the decline in social capital produced within the home.

Slow and fast components in the X-ray light curves of Gamma-Ray Bursts

Gamma-ray burst light curves show quite different patterns: from very simple to extremely complex. We present a temporal and spectral study of the light curves in three energy bands (2-5, 5-10, 10-26 keV) of ten GRBs detected by the Wide Field Cameras on board BeppoSAX. For some events the time profiles are characterized by peaks superposed on a slowly evolving pedestal, which in some cases becomes less apparent at higher energies. We describe this behaviour with the presence of two components (slow and fast) having different variability time scales. We modelled the time evolution of slow components by means of an analytical function able to describe asymmetric rising and decaying profiles. The residual light curves, after the subtraction of the slow components, generally show structures more similar to the original curves in the highest energy band. Spectral study of these two components was performed evaluating their hardness ratios, used also to derive photon indices. Slow components are found generally softer than the fast ones suggesting that their origin is likely different. Being typical photon indices lower than those of the afterglows there is no evidence that the emission processes are similar. Another interesting possibility is that slow components can be related to the presence of a hot photosphere having a thermal spectrum with kT around a few keV superposed to a rapid variable non-thermal emission of the fast component.Comment: 16 pages, 20 figures (18 color, 2 B&W), accepted for publication in Astronomy and Astrophysic

Forging a New Identity: The Costs and Benefits of Diversity in Civil War Combat Units for Black Slaves and Freemen

By the end of the Civil War, 186,017 black men had fought for the Union Army and roughly three-quarters of these men were former slaves. Because most of the black soldiers who served were illiterate farm workers, the war exposed them to a much broader world. The war experience of these men depended upon their peers, their commanding officers, and where their regiment toured. These factors affected the later life outcomes of black slaves and freemen. This paper documents both the short run costs and long run benefits of participating in a diverse environment. In the short run the combat unit benefited from company homogeneity as this built social capital and minimized shirking, but in the long run men's human capital and aquisition of information was best served by fighting in heterogeneous companies.

On the equivalence of Lambda(t) and gravitationally induced particle production cosmologies

The correspondence between cosmological models powered by a decaying vacuum energy density and gravitationally induced particle production is investigated. Although being physically different in the physics behind them we show that both classes of cosmologies under certain conditions can exhibit the same dynamic and thermodynamic behavior. Our method is applied to obtain three specific models that may be described either as Lambda(t)CDM or gravitationally induced particle creation cosmologies. In the point of view of particle production models, the later class of cosmologies can be interpreted as a kind of one-component unification of the dark sector. By using current type Ia supernovae data, recent estimates of the cosmic microwave background shift parameter and baryon acoustic oscillations measurements we also perform a statistical analysis to test the observational viability within the two equivalent classes of models and we obtain the best-fit of the free parameters. By adopting the Akaike information criterion we also determine the rank of the models considered here. Finally, the particle production cosmologies (and the associated decaying Lambda(t)-models) are modeled in the framework of field theory by a phenomenological scalar field model.Comment: 9 pages, 3 figures, new comments and 8 references added. Accepted for publication in Physics Letters