10 research outputs found

    Baade’s window and APOGEE: Metallicities, ages, and chemical abundances

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    International audienceContext. Baade’s window (BW) is one of the most observed Galactic bulge fields in terms of chemical abundances. Owing to its low and homogeneous interstellar absorption it is considered the perfect calibration field for Galactic bulge studies.Aims. In the era of large spectroscopic surveys, calibration fields such as BW are necessary for cross calibrating the stellar parameters and individual abundances of the APOGEE survey.Methods. We use the APOGEE BW stars to derive the metallicity distribution function (MDF) and individual abundances for α- and iron-peak elements of the APOGEE ASPCAP pipeline (DR13), as well as the age distribution for stars in BW.Results. We determine the MDF of APOGEE stars in BW and find a remarkable agreement with that of the Gaia-ESO survey (GES). Both exhibit a clear bimodal distribution. We also find that the Mg-metallicity planes of the two surveys agree well, except for the metal-rich part ([Fe/H] > 0.1), where APOGEE finds systematically higher Mg abundances with respect to the GES. The ages based on the [C/N] ratio reveal a bimodal age distribution, with a major old population at ~ 10 Gyr, with a decreasing tail towards younger stars. A comparison of stellar parameters determined by APOGEE and those determined by other sources reveals detectable systematic offsets, in particular for spectroscopic surface gravity estimates. In general, we find a good agreement between individual abundances of O, Na, Mg, Al, Si, K, Ca, Cr, Mn, Co, and Ni from APOGEE with that of literature values.Conclusions. We have shown that in general APOGEE data show a good agreement in terms of MDF and individual chemical abundances with respect to literature works. Using the [C/N] ratio we found a significant fraction of young stars in BW

    The Role of Culture and Gender in E-commerce Entrepreneurship: Three Jordanian Case Studies

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    The number of entrepreneurs using e-commerce to start their own online business up is continuously growing. In this chapter, the current literature on e-commerce entrepreneurship is reviewed and attention is paid to the situation in Jordan, a representative Middle East and Northern Africa (MENA) country. In particular, our focus is on the role of culture and gender on local potential, nascent and new e-entrepreneurs. Three Jordan case studies are presented (ZINC, Oasis500 and CashBasha), showing an increased attention and support for entrepreneurship in general, and e-entrepreneurship in particular, in Jordan. In addition, some special programs are aimed at promoting women e-entrepreneurship, since it is seen as a way to overcome some of the cultural barriers to female entrepreneurial activity
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