Chemodynamic evolution of dwarf galaxies in tidal fields

The mass-metallicity relation shows that the galaxies with the lowest mass have the lowest metallicities. As most dwarf galaxies are in group environments, interaction effects such as tides could contribute to this trend. We perform a series of smoothed particle hydrodynamics (SPH) simulations of dwarf galaxies in external tidal fields to examine the effects of tides on their metallicities and metallicity gradients. In our simulated galaxies, gravitational instabilities drive gas inwards and produce centralized star formation and a significant metallicity gradient. Strong tides can contribute to these instabilities, but their primary effect is to strip the outer low-metallicity gas, producing a truncated gas disk with a large metallicity. This suggests that the role of tides on the mass-metallicity relation is to move dwarf galaxies to higher metallicities.Comment: Accepted to Ap

Comparing Accuracy and Costs of Revealed and Stated Preferences: The Case of Consumer Acceptance of Yellow Maize in East Africa

For quite a while, stated preferences have been a major tool to measure consumer preferences for new products and services. Revealed preference methods, in particular experimental economics, have gained popularity recently because they have been shown to be more incentive compatible, and therefore more accurate. However, this advantage comes at the expense of higher survey costs. In the developing countries with limited funding for research, it is important to determine whether the extra cost can be justified by the extra gain in accuracy. A survey of 100 farmers was carried out in Western Kenya to determine consumer preference for yellow maize using the contingent valuation, choice experiments and experimental auction methods. Experimental auctions produced the most realistic results for mean willingness to pay. They are also the most accurate at all budget levels, but also the most expensive. Considering their accuracy and realistic results, we conclude that they should be the recommended method in measuring consumer preference in developing countries, since the extra cost is more than recovered by the gain in accuracy.Kenya, maize, consumer, experimental auctions, stated preference, WTP, Crop Production/Industries, Food Consumption/Nutrition/Food Safety, D6, Q12,

Pezoa Véliz, poeta social

Indexación: Revista UNABEl artículo podría titularse también Pezoa Véliz modernista, Pezoa Véliz poeta popular, Pezoa Véliz, poeta nacional, etc. porque el autor poseía múltiples facetas temáticas, de tono y de estilo. Se prefirió calificarlo como poeta social en atención a la índole de sus poemas más representativos. Pezoa Véliz vivió menos de 30 años a principios del siglo XX y no pudo alcanzar, por condiciones socio-económicas, una educación sistemática superior. Su gran modelo poético es Rubén Darío y sus logros son muy irregulares. Es poeta más de antología breve que de obras completas. En el grupo más escogido de sus poemas hay algunos como "Tarde en el hospital" que pueden parangonarse con los más logrados de la poesía chilena. Abstract: This article could be also called Pezoa Veliz modemist, popular poet Pezoa Veliz, national poet Pezoa Veliz, etc. cause the author had multiple topics, from tone and style. It rather called him as a social poet ín attention to the nature ofhis most representative poems. Pezoa Veliz Iived less than 30 year at the begínníng of the XXth century and he couldn't continue, for his socio economic conditions, to a superior sistematic education. His great poetic role is Ruben Dario and his achivements are pretty irregular. He's a poet more like anthology than complete pieces ofwork. In the selected group ofhis poems there are some as "Aftemoon ín the hospital" ("Tarde en el hospital") that can be compared with some ofthe best achievements ofthe chilean poetry

The Emergence of the Thick Disk in a CDM Universe II: Colors and Abundance Patterns

The recently emerging conviction that thick disks are prevalent in disk galaxies, and their seemingly ubiquitous old ages, means that the formation of the thick disk, perhaps more than any other component, holds the key to unravelling the evolution of the Milky Way, and indeed all disk galaxies. In Paper I, we proposed that the thick disk was formed in an epoch of gas rich mergers, at high redshift. This hypothesis was based on comparing N-body/SPH simulations to a variety of Galactic and extragalactic observations, including stellar kinematics, ages and chemical properties.Here examine our thick disk formation scenario in light of the most recent observations of extragalactic thick disks. In agreement, our simulted thick disks are old and relatively metal rich, with V-I colors that do not vary significantly with distance from the plane. Further, we show that our proposal results in an enhancement of alpha-elements in thick disk stars as compared with thin disk stars, consistent with observations of the relevant populations of the Milky Way. We also find that our scenario naturally leads to the formation of an old metal weak stellar halo population with high alpha-element abundances.Comment: submitted to Ap