Chandra observations of the interacting galaxies NGC 3395/3396 (Arp 270)

In this paper we present the results of a 20-ks high-resolution Chandra X-ray observation of the peculiar galaxy pair NGC 3395/3396, a system at a very early stage of merging, and less evolved than the famous Antennae and Mice merging systems. Previously unpublished ROSAT High-Resolution Imager data are also presented. The point-source population and the hot diffuse gas in this system are investigated and compared with other merging galaxy pairs. 16 X-ray point sources are detected in Arp 270, seven of which are classified as ultraluminous X-ray sources (ULXs, LX>= 1039 erg s-1). From spectral fits and the age of the system it seems likely that these are predominantly high-mass X-ray binaries. The diffuse gas emits at a global temperature of ~0.5 keV, consistent with temperatures observed in other interacting systems, and we see no evidence of the starburst-driven hot gaseous outflows seen in more evolved systems such as The Mice and The Antennae. It is likely that these features are absent from Arp 270 as the gas has had insufficient time to break out of the galaxy discs. 32 per cent of the luminosity of Arp 270 arises from the diffuse gas in the system, this is low when compared with later stage merging systems and gives further credence that this is an early-stage merger. Comparing the ULX population of Arp 270 to other merging systems, we derive a relationship between the star formation rate of the system, indicated by LFIR, and the number [N(ULX)] and luminosity (LULX) of its ULX population. We find N(ULX) ~L0.18FIR and LULX~L0.54FIR. These relationships, coupled with the relation of the point-source X-ray luminosity (LXP) to LK and LFIR+UV (Colbert et al. 2003), indicate that the ULX sources in an interacting system have contributions from both the old and young stellar populations.Peer reviewe

The Effect of Adolescent Experience on Labor Market Outcomes: The Case of Height

Taller workers receive a wage premium, and the disparity in wages is similar in magnitude to the race and gender gaps. We exploit the variation in an individual’s height over time to explore the ways in which height affects wages. Specifically, we show that for white males the effect of adult height is essentially eliminated when adolescent height is taken into account. We find that participation in high school sports and clubs, and to a lesser extent schooling, are channels through which teen height affects adult wages. The benefits of being a taller teen seem to accrue equally across income classes and also across broad occupation categories, suggesting that the benefits of teen height do not result from occupational sorting. Because height is heritable and because tall adults tend to have children with each other, the benefits of teen height tend to be perpetuated across generations. Finally, we use our estimates of the teen height premium to perform a simple calculation of the monetary benefits of a newly approved treatment for children that increases height.Confidence, Optimism, Behavioral Economics

The Effect of Adolescent Experience on Labor Market Outcomes: The Case of Height

Taller workers receive a wage premium. Net of differences in family background, the disparity is similar in magnitude to the race and gender gaps. We exploit variation in an individual's height over time to explore how height affects wages. Controlling for teen height essentially eliminates the effect of adult height on wages for white males. The teen height premium is not explained by differences in resources or endowments. The teen height premium is partly mediated through participation in high school sports and clubs. We estimate the monetary benefits of a medical treatment for children that increases height.

The Effect of Adolescent Experience on Labor Market Outcomes: The Case of Height, Third Version

Taller workers receive a wage premium. Net of differences in family background, the disparity is similar in magnitude to the race and gender gaps. We exploit variation in an individual’s height over time to explore how height affects wages. Controlling for teen height essentially eliminates the effect of adult height on wages for white males. The teen height premium is not explained by differences in resources or endowments. The teen height premium is partly mediated through participation in high school sports and clubs. We estimate the monetary benefits of a medical treatment for children that increases height.Confidence, Optimism, Behavioral Economics

The interaction of social and perceivable causal factors in shaping ‘over-imitation’

Over-imitation has become a well-documented phenomenon. However there is evidence that both social and visible, physically causal factors can influence the occurrence of over-imitation in children. Here we explore the interplay between these two factors, manipulating both task opacity and social information. Four- to 7-year-old children were given either a causally opaque or transparent box, before which they experienced either (1) a condition where they witnessed a taught, knowledgeable person demonstrate an inefficient method and an untaught model demonstrate a more efficient method; or (2) a baseline condition where they witnessed efficient and inefficient methods performed by two untaught models. Results showed that the level of imitation increased with greater task opacity and when children received social information about knowledgeability consequent on teaching, but only for 6- to 7-year-olds. The findings show that children are selectively attuned to both causal and social factors when learning new cultural knowledge

Solar gamma rays and modulation of cosmic rays in the inner heliosphere

The first evidence of the gamma-ray emission from the quiescent Sun was found in the archival EGRET data that was later confirmed by Fermi-LAT observations with high significance. This emission is produced by Galactic cosmic rays (CRs) penetrating the inner heliosphere and inter- acting with the solar atmosphere and optical photons. The solar emission is characterized by two spatially and spectrally distinct components: (i) disk emission due to the CR cascades in the solar atmosphere, and (ii) spatially extended inverse Compton (IC) emission due to the CR electrons scattering off of solar photons. The intensity of both components associated with Galactic CRs anti-correlate with the level of the solar activity being the brightest during solar minimum. In this paper we discuss updates of the models of the IC component of the emission based on CR measurements made at different levels of solar activity, and we make predictions for e- ASTROGAM and AMEGO, proposed low-energy gamma-ray missions.Comment: 7 pages, 3 figures, Proceedings of the 35th International Cosmic Ray Conference, ICRC201

The end of an era? The medium- and long-term effects of the global crisis on growth in low-income countries

This paper investigates the medium- and long-term growth effects of the global financial crises on Low-Income Countries (LICs). Using several methodological approaches, including impulse response function analysis, growth spells techniques and panel regressions, we show that external demand (ED) shocks are not historically associated with sharp declines in output growth. Given existing evidence that LICs were primarily impacted by such a shock in the global financial crisis, our analysis provides some optimism on the chances that LICs will avoid a protracted period of slow growth. However, we also show that there seem to be persistent output losses associated with ED shocks in the medium-run. In terms of policy implications, our analysis provides evidence that countries with lower deficits, lower debt, more flexible exchange rate regimes, and a higher stock of international reserves are more likely to dampen the effects of an ED shock on growth. --Global financial crisis,external shocks,low-income countries,medium- and long-term growth,impulse response functions,growth spells,panel growth regressions

Policy games, policy neutrality and Tinbergen controllability under rational expectations

This paper shows the relationship between static controllability (the well-known Tinbergen golden rule), and the existence and other properties of the Nash equilibrium in a dynamic setting with rational expectations for future behavior. We show how to determine the existence of equilibrium outcomes; the conditions under which no equilibrium exists; and who will get to dominate (or who will find their policies to have become ineffective) in those equilibria, without having to compute and enumerate all the possible equilibria directly.