Inhomogeneous Chemical Evolution of r-process Elements in the Galactic Halo

For the production of r-process elements in our Galaxy, multiple sites have been discussed, among others, core-collapse supernovae and neutron star mergers. We use the observed elemental abundances of europium (Eu) in metal poor stars to reproduce the galactic chemical evolution of r-process elements. Our main findings are that additionally to neutron star mergers, a second, early acting site is necessary. We assume “magnetorotationally driven supernovae” act as this additional and earlier r-process site and conclude that our simulations with an adequate combination of these two sites successfully reproduces the observed r-process elemental abundances in the Galactic halo

Galactic evolution of rapid neutron capture process abundances: the inhomogeneous approach

For the origin of heavy rapid neutron capture process (r-process) elements, different sources have been proposed, e.g. core-collapse supernovae or neutron star mergers. Old metal-poor stars carry the signature of the astrophysical source(s). Among the elements dominantly made by the r-process, europium (Eu) is relatively easy to observe. In this work we simulate the evolution of Eu in our Galaxy with the inhomogeneous chemical evolution (ICE) model, and compare our results with spectroscopic observations. We test the most important parameters affecting the chemical evolution of Eu: (a) for neutron star mergers the coalescence time-scale of the merger (tcoal) and the probability to experience a neutron star merger event after two supernova explosions occurred and formed a double neutron star system (PNSM) and (b) for the subclass of magnetorotationally driven supernovae (‘Jet-SNe'), their occurrence rate compared to standard supernovae (PJet-SN). We find that the observed [Eu/Fe] pattern in the Galaxy can be reproduced by a combination of neutron star mergers and Jet-SNe as r-process sources. While neutron star mergers alone seem to set in at too high metallicities, Jet-SNe provide a cure for this deficiency at low metallicities. Furthermore, we confirm that local inhomogeneities can explain the observed large spread in the Eu abundances at low metallicities. We also predict the evolution of [O/Fe] to test whether the spread in α-elements for inhomogeneous models agrees with observations and whether this provides constraints on supernova explosion models and their nucleosynthesi

Inhomogeneous chemical evolution of r-process elements

We report the results of a galactic chemical evolution (GCE) study for r-process- and alpha elements. For this work, we used the inhomogeneous GCE model "ICE", which allows to keep track of the galactic abundances of elements produced by different astrophysical sites. The main input parameters for this study were: a) The Neutron Star Merger (NSM) coalescence time scale, the probability of NSMs, and for the sub-class of "magneto-rotationally driven Supernovae" ("Jet-SNe"), their occurence rate in comparison to "standard" Supernovae (SNe)

Galactic evolution of rapid neutron capture process abundances: The inhomogeneous approach

For the origin of heavy r-process elements, different sources have been proposed, e.g., core-collapse supernovae or neutron star mergers. Old metal-poor stars carry the signature of the astrophysical source(s). Among the elements dominantly made by the r-process, europium (Eu) is relatively easy to observe. In this work we simulate the evolution of europium in our galaxy with the inhomogeneous chemical evolution model ’ICE’, and compare our results with spectroscopic observations. We test the most important parameters affecting the chemical evolution of Eu: (a) for neutron star mergers, the coalescence time scale of the merger (tcoal) and the probability to experience a neutron star merger event after two supernova explosions occurred and formed a double neutron star system (PNSM) and (b) for the sub-class of magneto-rotationally driven supernovae (”Jet-SNe”), their occurrence rate compared to standard supernovae (PJet−SN). We find that the observed [Eu/Fe] pattern in the galaxy can be reproduced by a combination of neutron star mergers and magneto-rotationally driven supernovae as r-process sources. While neutron star mergers alone seem to set in at too high metallicities, Jet-SNe provide a cure for this deficiency at low metallicities. Furthermore, we confirm that local inhomogeneities can explain the observed large spread in the europium abundances at low metallicities. We also predict the evolution of [O/Fe] to test whether the spread in α-elements for inhomogeneous models agrees with observations and whether this provides constraints on supernova explosion models and their nucleosynthesis

The Effect of Student-Directed Transition Planning With a Computer-Based Reading Support Program on the Self-Determination of Students With Disabilities

The purpose of this study was to investigate the impact of student-directed transition planning instruction (Whose Future Is It Anyway? curriculum) with a computer-based reading support program (Rocket Reader) on the self-determination, self-efficacy and outcome expectancy, and transition planning knowledge of students with disabilities. This study employed a pre- and postmeasure design with 168 middle school students with disabilities who were assigned to an experimental group (n = 86) and control group (n = 82). The results of the study demonstrated that self-determination, self-efficacy, and outcome expectancy for education planning improved through the application of Rocket Reader . Avenues are discussed for promoting middle school students’ self-determination in their transition planning, as are implications for future research.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Enhancing staff attitudes, knowledge and skills in supporting the self-determination of adults with intellectual disability in residential settings in Hong Kong: A pretest-posttest comparison group design

Background: The ecological perspective recognizes the critical role that is played by rehabilitation personnel in helping people with intellectual disability (ID) to exercise self-determination, particularly in residential settings. In Hong Kong, the authors developed the first staff training programme of its kind to strengthen the competence of personnel in this area. The purpose of this study was to examine the effectiveness of staff training in enhancing residential staff's attitudes, knowledge and facilitation skills in assisting residents with ID to exercise self-determination. Methods: A pretest-posttest comparison group design was adopted. Thirty-two participants in an experimental group attended a six-session staff training programme. A 34-item self-constructed scale was designed and used for measuring the effectiveness of the staff training. Results: The results showed that the experimental group achieved statistically significant positive changes in all domains, whereas no significant changes were found in the comparison group. Conclusions: The findings provided initial evidence of the effectiveness of staff training that uses an interactional attitude-knowledge-skills model for Chinese rehabilitation personnel. The factors that contributed to its effectiveness were discussed and recommendations for future research were made. © Journal Compilation © 2007 Blackwell Publishing Ltd.postprin

A Randomized-Trial Evaluation of the Effect of Whose Future Is It Anyway? on Self-Determination

Promoting student involvement in planning has become best practice in the field of transition. Research documents the positive impact of such efforts on greater student involvement. Research also suggests that promoting student involvement results in greater student self-determination, but a causal link has not been established. This study used a randomized- trial, placebo control group design to study the impact of intervention with the Whose Future Is It Anyway? process on self-determination. The authors also examined the impact of intervention on transition knowledge and skills. Results indicated that instruction using the Whose Future Is It Anyway? process resulted in significant, positive differences in self- determination when compared with a placebo-control group and that students who received instruction gained transition knowledge and skills.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Using failed supernovae to constrain the Galactic r-process element production

Rapid neutron capture process (r-process) elements have been detected in a large fraction of metal-poor halo stars, with abundances relative to iron (Fe) that vary by over two orders of magnitude. This scatter is reduced to less than a factor of 3 in younger Galactic disc stars. The large scatter of r-process elements in the early Galaxy suggests that the r-process is made by rare events, like compact binary mergers and rare sub-classes of supernovae. Although being rare, neutron star mergers alone have difficulties to explain the observed enhancement of r-process elements in the lowest metallicity stars compared to Fe. The supernovae producing the two neutron stars already provide a substantial Fe abundance where the r-process ejecta from the merger would be injected. In this work we investigate another complementary scenario, where the r-process occurs in neutron star-black hole mergers in addition to neutron star mergers. Neutron star-black hole mergers would eject similar amounts of r-process matter as neutron star mergers, but only the neutron star progenitor would have produced Fe. Furthermore, a reduced efficiency of Fe production from single stars significantly alters the age-metallicity relation, which shifts the onset of r-process production to lower metallicities. We use the high-resolution [(20 pc)3/cell] inhomogeneous chemical evolution tool `ICE' to study the outcomes of these effects. In our simulations, an adequate combination of neutron star mergers and neutron star-black hole mergers qualitatively reproduces the observed r-process abundances in the Galaxy

Optimum Preplant Nitrogen Rates for Maize (Zea Mays L.) And Sorghum (Sorghum Bicolor L.) Production

Nitrogen Use Efficiency (NUE) for maize (Zea mays L.) production is low in the developed and developing world. Nitrogen application rates both preplant and sidedress need to be adjusted based on variables such as the environment, peak demand, and field-to-field variability which are known to change from one year to the next. This study was conducted to determine the minimum up-front fertilizer N rates, needed to improve mid-season fertilizer N use efficiencies, and determine periods of maximum N demand. Four field experiments were conducted where N as urea ammonium nitrate (UAN, 28-0-0, N-P-K) was applied preplant at rates of 0, 17, 34, 51, 67, and 168 kg N ha-1. Preplant fertilizer was applied on April 6 for EFAW and Perkins, and April 7 Lake Carl Blackwell. Normalized difference vegetative index (NDVI) data were collected from the V6 to V10 growth stages. At V6, sidedress N was applied at rates of 168 kg N ha-1 for treatments 8 through 14. Due to faculty-design-treatment-structure errors, this maize N study will be conducted in the 2017 growing season. This study will determine the minimum preplant N rate needed combined with sidedress N for maximum yields in maize. Grain sorghum (Sorghum bicolor L.) production similar to Maize (Zea mays L.) needs to take place at much higher levels of nitrogen use efficiency (NUE) than it is achieved today. Nitrogen application rates, both preplant and sidedress, need to be adjusted based on variables such as the environment, peak demand, and field to field variability which are known to change from one year to the next. This study was initiated to determine the minimum pre-plant fertilizer N rates needed to improve mid-season fertilizer N use efficiencies, and to determine periods of maximum N demand. Two field experiments were conducted where N as urea ammonium nitrate (UAN, 28-0-0, N-P-K) was applied preplant at rates of 0, 17, 34, 50, 67, and 101 kg N ha-1. Preplant fertilizer was applied on April 6 for EFAW, and April 15 for Lake Carl Blackwell. Normalized difference vegetative index data were collected at 512, 732, 1080, and 1341 total degree day heat units. At 830 total degree day heat units, sidedress N was applied at a rate of 34 kg N ha-1 for treatments 7 through 12. The preplant N rate for these studies was 67 kg N ha-1 (Tables 6 and 7). In order to maximize yields, at least 34 kg N ha-1 applied sidedress was needed.Plant & Soil Science

Exploring Personal and Environmental Characteristics that Predict Self-Determination

This is the author's accepted manuscript. The original publication is available at http://dx.doi.org/10.1080/09362835.2013.802231.This study examined the degree to which multiple personal (age, gender, disability, and need for educational support) and school environment characteristics (hours in academic classes with general education peers, hours in nonacademic classes with age-peers, attendance at the most recent individualized education plan [IEP] meeting, transition goal for the future on the IEP, and experience with setting goals for the future) predicted student's relative level of self-determination. Age, disability label, hours in academic classes with general education peers, and goal setting experience were significant predictors, accounting for 22% of the variance in self-determination scores. Implications for future research and practice are discussed