Neutron-capture elements in the very metal-poor star HD88609: another st ar with excesses of light neutron-capture elements

We obtained a high resolution, high signal-to-noise UV-blue spectrum of the extremely metal-poor red giant HD88609 to determine the abundances of heavy elements. Nineteen neutron-capture elements are detected in the spectrum. Our analysis revealed that this object has large excesses of light neutron-capture elements while heavy neutron-capture elements are deficient. The abundance pattern shows a continuously decreasing trend, as a function of atomic number, from Sr to Yb, which is quite different from those in stars with excesses of r-process elements. Such an abundance pattern is very similar to that of HD122563 that was studied by our previous work. The results indicate that the abundance pattern found in the two stars could represent the pattern produced by the nucleosynthesis process that provided light neutron-capture elements in the very early Galaxy.Comment: 18 pages, 6 figures, accepted for publication in Ap

Outgassing measurement of the aluminum alloy UHV chamber

A large vacuum chamber (580 mm diameter) was fabricated from an aluminum alloy surface treated by a special process normally used on small chambers. The chamber was tested unbaked and baked at various temperatures, pressures, and holding periods. The chamber was filled with N2 gas, and the outgassing rate was measured after one hour. Then the ultimate pressure was measured. Outgassing rates for baked and unbaked groups were compared. It is concluded that the same surface treatment technique can be used on both large and small chambers produced by the same special extrusion process

Liderazgo equitativa “on the ground”: Convergindo em práticas de alta influência

What would leadership standards look like if developed through a lens and language of equity? We engaged with a group of 40 researchers, practitioners, and community leaders recognized as having expertise on equity in education to address this question. Using a Delphi technique, an approach designed to elicit expert feedback and measure convergence around a question of interest, these leaders participated in three rounds of data gathering. In Rounds One and Two, the 40 participants described and then rated leadership practices they believed to be most likely to mitigate race, class, and other group-based disparities between dominant and nondominant students. In Round Three, 14 of these experts participated in focus group sessions, using the findings from the first two rounds to ultimately converge around 10 high-leverage leadership practices for equity. Findings highlight the importance of leadership centered on countering systemic and structural barriers that maintain disparities, with implications for leadership preparation, policy, and tools to support organizational leadership for equity.Como serían los principales estándares de si se desarrollan a través de un lenguaje de la lente y la equidad? Nos comprometemos con un grupo de 40 investigadores, profesores de educación básica y líderes comunitarios reconocidos por su experiencia en la equidad en la educación para abordar esta cuestión. Usando una técnica Delphi, un enfoque conocido para extraer información y medir la convergencia en torno a una cuestión de interés, estos líderes participaron en tres rondas de recolección de datos. En las primeras rondas, los 40 participantes describen y clasifican las prácticas de los líderes que ellos pensaban que eran más propensos a mitigar las disparidades entre raza, clase y otros grupos, incluyendo a los estudiantes de los grupos dominantes y no dominantes. En la última ronda, 13 de estos líderes participaron en sesiones de grupos focales, utilizando los resultados de las dos primeras rondas para finalmente convergen alrededor de 10 prácticas de liderazgo de alto impacto para la equidad. Los resultados ponen de manifiesto la importancia del liderazgo centrado en la lucha contra las barreras sistémicas y estructurales que mantienen diferencias con implicaciones para la preparación de líderes, políticas y herramientas para apoyar el liderazgo de la organización para la equidad.Como os padrões de liderança seriam se fossem desenvolvidos através de uma lente e linguagem de equidade? Nos engajamos com um grupo de 40 pesquisadores, professores da educação básica e líderes de comunidades reconhecidos por terem experiências em equidade na educação para abordar essa questão. Utilizando uma técnica de Delphi, uma aproximação designada para extrair um feedback e medir a convergência em torno de uma pergunta de interesse, esses líderes participaram em três rodadas da coleta de dados. Nas primeiras rodadas, os 40 participantes descreveram e classificaram as práticas de lideranças que eles acreditavam serem mais propensas a mitigar as disparidades entre raça, classe e outros grupos, entre estudantes de grupos dominantes e não-dominantes. Na última rodada, 13 desses líderes participaram em sessões de grupo focal, usando os resultados das duas primeiras rodadas para, finalmente, convergir em torno de 10 práticas de liderança de alta influência para a equidade. Os resultados destacam a importância da liderança centrada na luta contra as barreiras sistêmicas e estruturais que mantêm disparidades, com implicações para a preparação de lideranças, políticas e ferramentas para apoiar a liderança organizacional pela equidade

Enrichment of the r-process Element Europium in the Galactic Halo

We investigate the enrichment of europium, as a representative of r-process elements, in the Galactic halo. In present chemical evolution models, stars are assumed to be formed through shock processes by supernovae (SNe). The enrichment of the interstellar medium is calculated by a one-zone approach. The observed large dispersions in [Eu/Fe] for halo stars, converging with increasing metallicity, can be explained with our models. In addition, the mass range of SNe for the {\it r}-process site is constrained to be either stars of $8-10 M_\odot$ or $\gtrsim 30 M_\odot$.Comment: 5 pages (including 4 figures), LaTeX, uses aas2pp4.sty, accepted to ApJ

Comparison of different methods of temporomandibular joint disc reconstruction - An animal model

The document attached has been archived with permission from the Australian Dental Association. An external link to the publisher’s copy is included. Article first published online: 12 MAR 2008The optimum method of temporomandibular joint (TMJ) reconstruction has not been defined despite numerous surgical treatments and several well controlled clinical trials. Animal models offer an experimental method allowing direct comparison of standardized surgical techniques. Advanced osteoarthrosis was induced bilaterally in 12 mature merino sheep. Three months later unilateral surgical reconstruction was performed. Four sheep had discectomy alone, four discectomy with fresh TMJ disc grafts, and four discectomy with fresh auricular grafts. All three surgical methods resulted in some reversal and repair of the osteoarthritic process, with the best result being from the auricular graft, next discectomy alone, next the disc graft, with the untreated osteoarthritic joint showing the most advanced pathosis. This study supports the role of surgical reconstruction in advanced degenerative disease of the temporomandibular joint, in particular, auricular graft reconstruction.Nobumi Ogi, Jun-Ichi Ishimaru, Kenichi Kurita, Yujiro Handa, Robert H.B. Jones, Alastair N. Gos

Light-cone fluctuations and the renormalized stress tensor of a massless scalar field

We investigate the effects of light-cone fluctuations over the renormalized vacuum expectation value of the stress-energy tensor of a real massless minimally coupled scalar field defined in a ($d+1$)-dimensional flat space-time with topology ${\cal R}\times {\cal S}^d$. For modeling the influence of light-cone fluctuations over the quantum field, we consider a random Klein-Gordon equation. We study the case of centered Gaussian processes. After taking into account all the realizations of the random processes, we present the correction caused by random fluctuations. The averaged renormalized vacuum expectation value of the stress-energy associated with the scalar field is presented

Explosive nucleosynthesis in core-collapse supernovae

The specific mechanism and astrophysical site for the production of half of the elements heavier than iron via rapid neutron capture (r-process) remains to be found. In order to reproduce the abundances of the solar system and of the old halo stars, at least two components are required: the heavy r-process nuclei (A>130) and the weak r-process which correspond to the lighter heavy nuclei (A<130). In this work, we present nucleosynthesis studies based on trajectories of hydrodynamical simulations for core-collapse supernovae and their subsequent neutrino-driven winds. We show that the weak r-process elements can be produced in neutrino-driven winds and we relate their abundances to the neutrino emission from the nascent neutron star. Based on the latest hydrodynamical simulations, heavy r-process elements cannot be synthesized in the neutrino-driven winds. However, by artificially increasing the wind entropy, elements up to A=195 can be made. In this way one can mimic the general behavior of an ejecta where the r-process occurs. We use this to study the impact of the nuclear physics input (nuclear masses, neutron capture cross sections, and beta-delayed neutron emission) and of the long-time dynamical evolution on the final abundances.Comment: 10 pages, 8 figures, invited talk, INPC 2010 Vancouver, Journal of Physics: Conference Serie