Institution
University of Groningen
Education•Groningen, Groningen, Netherlands•
About: University of Groningen is a education organization based out in Groningen, Groningen, Netherlands. It is known for research contribution in the topics: Population & Context (language use). The organization has 36346 authors who have published 69116 publications receiving 2940370 citations. The organization is also known as: Rijksuniversiteit Groningen & RUG.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this paper, the authors used the Ultraviolet Echelle Spectrograph (UVES) on Kueyen (UT2) of the Very Large Telescope to take spectra of 15 individual red giants in the Sculptor, Fornax, Carina, and Leo I dwarf spheroidal galaxies (dSph's).
Abstract: We have used the Ultraviolet Echelle Spectrograph (UVES) on Kueyen (UT2) of the Very Large Telescope to take spectra of 15 individual red giants in the Sculptor, Fornax, Carina, and Leo I dwarf spheroidal galaxies (dSph's). We measure the abundances of α-, iron peak, first s-process, second s-process, and r-process elements. No dSph giants in our sample show the deep mixing abundance pattern (O and sometimes Mg depleted, while Na and Al are enhanced) seen in nearly all globular clusters. At a given metallicity the dSph giants exhibit lower [el/Fe] abundance ratios for the α-elements than stars in the Galactic halo. The low α abundances at low metallicities can be caused by a slow star formation rate and contribution from Type Ia SNe, and/or a small star formation event (low total mass) and mass-dependent Type II SN yields. In addition, Leo I and Sculptor exhibit a declining even-Z [el/Fe] pattern with increasing metallicity, while Fornax exhibits no significant slope. In contrast, Carina shows a large spread in the even-Z abundance pattern, even over small metallicity ranges, as might be expected from a bursting star formation history. The metal-poor stars in these dSph galaxies ([Fe/H] < -1) have halo-like s- and r-process abundances, but not every dSph exhibits the same evolution in the s- and r-process abundance pattern. Carina, Sculptor, and Fornax show a rise in the s-/r-process ratio with increasing metallicity, evolving from a pure r-process ratio to a solar-like s- and r-process ratio. On the other hand, Leo I, appears to show an r-process–dominated ratio over the range in metallicities sampled. At present, we attribute these differences in the star formation histories of these galaxies. Comparison of the dSph abundances with those of the halo reveals some consistencies with the Galactic halo. In particular, Nissen & Shuster found that their metal-rich, high Rmax high zmax halo stars exhibited low [α/Fe], [Na/Fe] and [Ni/Fe] abundance ratios. In the same abundance range our dSph exhibit the same abundance pattern, supporting their suggestions that disrupted dSph's may explain up to 50% of the metal-rich halo. Unfortunately, similar comparisons with the metal-poor Galactic halo have not revealed similar consistencies, suggesting that the majority of the metal-poor Galactic halo could not have been formed from objects similar to the dSph studied here. We use the dSph abundances to place new constraints on the nucleosynthetic origins of several elements. We attribute differences in the evolution of [Y/Fe] in the dSph stars versus the halo stars to a very weak AGB or SN Ia yield of Y (especially compared with Ba). That a lower and flatter Ba/Y ratio is seen in the halo is most likely a result of the pattern being erased by the large metallicity dispersion in the halo. Also, we find [Cu/Fe] and [Mn/Fe] are flat and halo-like over the metallicity city range -2 < [Fe/H] < -1.2, and that the [Cu/α] ratios are flat. Combining these abundances with knowledge of the age spread in these galaxies suggests that SNe Ia are not the main site for the production of Cu (and Mn) in very metal-poor stars. We suggest that metallicity-dependent SN yields may be more promising.
541 citations
•
TL;DR: This article found that prosocial spending is consistently associated with greater happiness and that the reward experienced from helping others may be deeply ingrained in human nature, emerging in diverse cultural and economic contexts.
Abstract: This research provides the first support for a possible psychological universal: human beings around the world derive emotional benefits from using their financial resources to help others (prosocial spending). Analyzing survey data from 136 countries, we show that prosocial spending is consistently associated with greater happiness. To test for causality, we conduct experiments within two very different countries (Canada and Uganda) and show that spending money on others has a consistent, causal impact on happiness. In contrast to traditional economic thought--which places self-interest as the guiding principle of human motivation--our findings suggest that the reward experienced from helping others may be deeply ingrained in human nature, emerging in diverse cultural and economic contexts.
541 citations
••
TL;DR: The development of molecular switches and the discoveries that culminated in the first light-driven molecular motor are described and the construction of the first and second generation molecular motors are presented.
Abstract: The design of molecular systems in which controlled linear and rotary motion can be achieved under the influence of an external signal is a major endeavor toward future nanoscale machinery. In this Account we describe the development of molecular switches and the discoveries that culminated in the first light-driven molecular motor. Various chiral optical molecular switches and their use as trigger elements to control organization and functions will be discussed. The construction of the first and second generation molecular motors is presented.
541 citations
••
TL;DR: Performance of a more accurate GFR-estimating equation, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, is reported by level of GFR and clinical characteristics and is more accurate than the MDRD Study equation overall and across most subgroups.
541 citations
••
TL;DR: This paper proposes a new measurement method: the Resource Generator; an instrument with concretely worded items covering 'general' social capital in a population, which combines advantages of earlier techniques.
540 citations
Authors
Showing all 36692 results
Name | H-index | Papers | Citations |
---|---|---|---|
Ronald C. Kessler | 274 | 1332 | 328983 |
Nicholas J. Wareham | 212 | 1657 | 204896 |
André G. Uitterlinden | 199 | 1229 | 156747 |
Lei Jiang | 170 | 2244 | 135205 |
Brenda W.J.H. Penninx | 170 | 1139 | 119082 |
Richard H. Friend | 169 | 1182 | 140032 |
Panos Deloukas | 162 | 410 | 154018 |
Jerome I. Rotter | 156 | 1071 | 116296 |
Christopher M. Dobson | 150 | 1008 | 105475 |
Dirk Inzé | 149 | 647 | 74468 |
Scott T. Weiss | 147 | 1025 | 74742 |
Dieter Lutz | 139 | 671 | 67414 |
Wilmar B. Schaufeli | 137 | 513 | 95718 |
Cisca Wijmenga | 136 | 668 | 86572 |
Arnold B. Bakker | 135 | 506 | 103778 |