Massive Stellar Content of the Galactic Supershell GSH 305+01-24

The distribution of OB stars along with that of H$\alpha$, $^{12}$CO, dust infrared emission, and neutral hydrogen is carried out in order to provide a more complete picture of interactions of the young massive stars and the observed supershell GSH 305+01-24. The studied field is located between $299^\circ \le l \le 311^\circ$ and $-5^\circ \le b \le 7^\circ$. The investigation is based on nearly 700 O-B9 stars with $uvby\beta$ photometry currently available. The derived stellar physical parameters were used to establish a homogeneous scale for the distances and extinction of light for major apparent groups and layers of foreground and background stars in Centaurus and study the interaction with the surrounding interstellar medium. The distance to the entire Centaurus star-forming complex is revised and a maximum of the OB-star distance distribution is found at 1.8$\pm$0.4 (r.m.s) kpc. The massive star component of GSH 305+01-24 is identified at about 85-90 % completeness up to 11.5-12 mag. The projected coincidence of the OB stars with the shell and the similarities between the shell's morphology and the OB-star distribution indicate a strong interaction of the stellar winds with the superbubble material. We demonstrate that these stars contribute a sufficient wind injection energy in order to explain the observed size and expansion velocity of the supershell. The derived stellar ages suggest an age gradient over the Coalsack Loop. A continuous star-formation might be taking place within the shell with the youngest stars located at its periphery and the open cluster NGC 4755 being the oldest. A layer of very young stars at 1 kpc is detected and its connection to both GSH 305+01-24 and the foreground GSH 304-00-12 H I shells is investigated.Comment: Accepted for publication in A&A. Paper consists of 11 pages, 3 tables and 9 figures. Table 1 and Table 3 will only be available from CD

A new magnetic white dwarf : PG2329+267

We have discovered that the white dwarf PG 2329+267 is magnetic, and assuming a centered dipole structure, has a dipole magnetic field strength of approximately 2.3MG. This makes it one of only approximately 4% of isolated white dwarfs with a detectable magnetic field. Linear Zeeman splitting as well as quadratic Zeeman shifts are evident in the hydrogen Balmer sequence and circular spectropolarimetry reveals 10% circular polarisation in the two displaced sigma components of Halpha. We suggest from comparison with spectra of white dwarfs of known mass that PG 2329+267 is more massive than typical isolated white dwarfs, in agreement with the hypothesis that magnetic white dwarfs evolve from magnetic chemically peculiar Ap and Bp type main sequence stars.Comment: 5 pages, with 2 encapsulated postscipts figures include

The argentine crisis and its contagion effects on latin american markets

Financial and exchange rate crises in emerging countries during the last decade have generated increasing interest in the subject of contagion. In this paper we present evidence of spillover effects during the incubation of the Argentine crisis on two Latin American countries. As expected, our results indicate that informational shocks affected mainly Argentina. Even though we find evidence of contagion effects on Chile and Brazil during argentine-related announcements, the general evidence indicates that foreign investors did not rebalance their portfolios away from non-Argentine Latin American markets during the pre-crisis period. It indicates that foreign investors do not perceive Latin American countries as one fully integrated market

The Relation of Adolescent Narcissism and Prosocial Behavior with Cooperative and Competitive Attitudes

Narcissism has been correlated with prosocial behavior in adolescents (Kauten & Barry, 2014, 2016). However, whether adolescents with high levels of narcissism use more egoistic (i.e., self-serving) or altruistic (i.e., helping others with no direct personal benefit) prosocial behaviors has not been investigated. This issue was addressed in the present study, and attitudes of cooperation and competition were also examined as moderators in these relations. The current study involved 147 at-risk adolescents, ages 16 to 18 (113 males, 34 females) who were enrolled in a residential program. The data were collected through self-report questionnaires which assessed narcissism (i.e., non-pathological, grandiose, vulnerable, and communal), prosocial tendencies, and cooperative and competitive attitudes. Non-pathological and grandiose narcissism were positively correlated with egoistic prosocial behaviors, whereas non-pathological and communal narcissism were positively correlated with altruistic prosocial behaviors. Adolescents reporting both high levels of vulnerable narcissism and high levels of competitive attitudes reported engaging in more altruistic prosocial behaviors than those with low levels of competitive attitudes. The same trend was evident for grandiose narcissism. The implications of these findings and the study’s limitations are discussed

A technique for passive attitude control of solar oriented interplanetary spacecraft

Passive damping technique for attitude control of solar orientated interplanetary spacecraf

RadioAstron probes the ultra-fine spatial structure in the H2_2O maser emission in the star forming region W49N

H$_2$O maser emission associated with the massive star formation region W49N were observed with the Space-VLBI mission RadioAstron. The procedure for processing of the maser spectral line data obtained in the RadioAstron observations is described. Ultra-fine spatial structures in the maser emission were detected on space-ground baselines of up to 9.6 Earth diameters. The correlated flux densities of these features range from 0.1% to 0.6% of the total flux density. These low values of correlated flux density are probably due to turbulence either in the maser itself or in the interstellar medium.Comment: Accepted for publication in Advances in Space Researc

The asymmetric profile of the H76 alpha line emission from MWC349

MWC349 is an emission-line star found by Merrill, Humason and Burwell (1932). Braes, Habing and Schoenmaker (1972) discovered that it is a strong radio source. The radio emission originates in a massive ionized wind that is expanding with a velocity of about 50 km s(-1). Its continuum spectrum fits well a nu(0.6) power law from the cm wavelengths to the far-IR. Radio recombination line emission from the envelope of MWC349 was first detected by Altenhoff, Strittmatter and Wendker (1981). We have obtained good signal-to-noise ratio, Very Large Array observations of the H76 alpha radio recombination line from the ionized wind of MWC349. Our data reveal that the profile is markedly asymmetric, with a steep rise on the blue side. This asymmetry could be due to non-LTE effects in the formation and transfer of the line or to intrinsic asymmetries in the envelope. Our analysis suggests that most probably the peculiar profile is caused by a non-LTE enhancement of the line emission from the side of the envelope nearer to the observer. This asymmetry has the opposite sense than that observed in optical and IR recombination lines, where a different effect (absorption of the stellar continuum by the gas in the wind between the star and the observer) is known to be dominant, leading to the classic P Cygni profile. We propose that the profiles of the radio recombination lines from ionized stellar winds will have this characteristic shape, while optical and IR recombination lines are characterized by P Cygni-like profiles. Unfortunately, at present the detection of radio recombination lines from ionized stellar winds is only feasible for MWC349 and a few other objects

The human side of mergers and acquisitions: a look at the evidence

22 p.This paper surveys the strategy literature on human resources’ role in the process of mergers and acquisitions. Although many studies acknowledge the important role of the “human” side in these major events in the life of a firm, we do not have up to now a comprehensive and encompassing survey of this literature. At the micro level we find consistent results across studies, mainly supporting the idea that M&A are disruptive events in the lives of the employees involved, they lead to increased stress and uncertainty which leads to dysfunctional outcomes. However the evidence is not so clear on whether these observed psychological and behavioral reactions have an impact on performance (at the individual or firm level). From a macro level perspective the hypothesis of a fit between the merging firms seems to have some empirical support, as it is found to have a positive impact on performance across the studies surveyed. The dynamic effects of this fit hypothesis, though, are not well understood yet. The impact and importance of social and formal controls and cultural fit are issues still begging for an explanation