Properties of dust in the detached shells around U Ant, DR Ser, and V644 Sco

Understanding the properties of dust produced during the asymptotic giant branch phase of stellar evolution is important for understanding the evolution of stars and galaxies. Recent observations of the carbon AGB star R Scl have shown that observations at far-infrared and submillimetre wavelengths can effectively constrain the grain sizes in the shell, while the total mass depends on the structure of the grains (solid vs. hollow or fluffy). We aim to constrain the properties of the dust observed in the submillimetre in the detached shells around the three carbon AGB stars U Ant, DR Ser, and V644 Sco, and to investigate the constraints on the dust masses and grain sizes provided by far-infrared and submm observations. We observed the carbon AGB stars U Ant, DR Ser, and V644 Sco at 870 micron using LABOCA on APEX. Combined with observations from the optical to far-infrared, we produced dust radiative transfer models of the spectral energy distributions (SEDs) with contributions from the stars, present-day mass-loss and detached shells. We tested the effect of different total dust masses and grain sizes on the SED, and attempted to consistently reproduce the SEDs from the optical to the submm. We derive dust masses in the shells of a few 10e-5 Msun, assuming spherical, solid grains. The best-fit grain radii are comparatively large, and indicate the presence of grains between 0.1 micron-2 micron. The LABOCA observations suffer from contamination from 12CO(3-2), and hence gives fluxes that are higher than the predicted dust emission at submm wavelengths. We investigate the effect on the best-fitting models by assuming different degrees of contamination and show that far-infrared and submillimetre observations are important to constrain the dust mass and grain sizes in the shells.Comment: Accepted by A&

Search for Associations Containing Young stars (SACY): Chemical tagging IC 2391 & the Argus association

We explore the possible connection between the open cluster IC 2391 and the unbound Argus association identified by the SACY survey. In addition to common kinematics and ages between these two systems, here we explore their chemical abundance patterns to confirm if the two substructures shared a common origin. We carry out a homogenous high-resolution elemental abundance study of eight confirmed members of IC 2391 as well as six members of the Argus association using UVES spectra. We derive spectroscopic stellar parameters and abundances for Fe, Na, Mg, Al, Si, Ca, Ti, Cr, Ni and Ba. All stars in the open cluster and Argus association were found to share similar abundances with the scatter well within the uncertainties, where [Fe/H] = -0.04 +/-0.03 for cluster stars and [Fe/H] = -0.06 +/-0.05 for Argus stars. Effects of over-ionisation/excitation were seen for stars cooler than roughly 5200K as previously noted in the literature. Also, enhanced Ba abundances of around 0.6 dex were observed in both systems. The common ages, kinematics and chemical abundances strongly support that the Argus association stars originated from the open cluster IC 2391. Simple modeling of this system find this dissolution to be consistent with two-body interactions.Comment: 17 pages, 7 figs, accepted for publication in MNRA

Experimental evidence of laser power oscillations induced by the relative Fresnel (Goos-Haenchen) phase

The amplification of the relative Fresnel (Goos-Haenchen) phase by an appropriate number of total internal reflections and the choice of favorable incidence angles allow to observe full oscillations in the power of a DPSS laser transmitted through sequential BK7 blocks. The experimental results confirm the theoretical predictions. The optical apparatus used in this letter can be seen as a new type of two-phase ellipsometric system where the phase of the complex refractive index is replaced by the relative Fresnel (Goos-Haenchen) phase.Comment: 7 pages, 3 figures, 1 tabl

Some properties of two Nambu--Jona-Lasinio -type models with inputs from lattice QCD

We investigate the phase diagram of the so-called Polyakov--Nambu--Jona-Lasinio (PNJL) model at finite temperature and nonzero chemical potential. The calculations are performed in the light and strange quark sectors ($u$, $d$, $s$), which includes the 't Hooft instanton induced interaction term that breaks the axial symmetry, and the quarks are coupled to the (spatially constant) temporal background gauge field. On one hand, a special attention is payed to the critical end point (CEP). The strength of the flavor-mixing interaction alters the CEP location, since when it becomes weaker the CEP moves to low temperatures and can even disappear. On the other hand, we also explore the connection between QCD, a nonlocal Nambu--Jona-Lasinio type model and the Landau gauge gluon propagator. Possible links between the quenched gluon propagator and low energy hadronic phenomenology are investigated.Comment: Contribution to the International Meeting "Excited QCD", Peniche, Portugal, 06 - 12 May 201

Aptidão da cultura do mamoeiro para o Estado da Bahia.

O Brasil produziu aproximadamente 1,79 milhão de toneladas de frutos de mamão no ano de 2009. A Bahia, maior estado produtor do País, respondeu por aproximadamente 49,7% desse total, seguido do Espírito Santo (30,6%) e Ceará (5,85%). O cultivo do mamoeiro na Bahia é desenvolvido predominantemente em condições de sequeiro, sendo o estresse por deficiência hídrica o principal fator limitante para expansão da área de plantio e o principal critério utilizado nos trabalhos de zoneamento climático no Nordeste brasileiro.PDF. n. 101_11

Um sistema web para mapeamento da oferta de software para o agronegócio.

Este pôster apresenta um sistema Web para mapeamento do mercado ofertante de software para o agronegócio. As informações disponíveis foram levantadas de empresas privadas do setor. O sistema foi validado por especialistas e mostrou-se eficiente na recuperação de informação, qualidade e segurança.Poster. Trabalho apresentado na V Mostra de Trabalhos de Estagiários e Bolsistas, Campinas, out. 2009

Academics engaging in knowledge transfer and co-creation: push causation and pull effectuation?

Although academics are increasingly engaging with businesses, some fundamental aspects of this phenomenon (i.e., their motivations, decision-making approaches, and the interplay between the two) remain understudied. We therefore conducted a qualitative inductive study comprising 68 interviews with academics who had engaged in two forms of activities—knowledge transfer and co-creation. Whereas the entrepreneurship literature offers a resource-based argument, we made an original contribution to the literature by introducing an engagement-based argument in order to offer a more accurate prediction of the motivations and decision-making approaches of academics engaged in knowledge transfer and co-creation activities. We found that when the resource- and engagement-based arguments offer different predictions of the interplay between the motivations and decision-making approaches adopted, the cognitive proximity between academics and business researchers, which reflects whether the partners are from the same/different disciplines, resolves the puzzle. We captured these situational contingencies by developing six propositions that indicate how the engagement- and resource-based arguments jointly offer a more comprehensive explanation of the interplay. We discuss the implications of our findings with regard to how universities could offer customized training, rewards, and support structures based on the four types of interplay between the motivation and decision-making approaches

Effect of ozone treatment in wheat quality of whole grain wheat flour.

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