The stratified evolution of a cool star

A low mass star usually experiences stratification and abundance anomalies during its evolution. A 0.95 solar mass star with a metallicity Z = 0.004 is followed from the main-sequence to the Horizontal Branch (HB). On the main-sequence the larger effects of stratification may come from accretion as was suggested in relation to metallicity and planet formation. As it evolves through the giant branch, stratification appears around the hydrogen burning shell. It may create hydrodynamic instabilities and be related to abundance anomalies on the giant branch. After the He flash the star evolves to the HB. If it loses enough mass, it ends up a hot HB star (or in the field an sdB star) with effective temperatures larger than 11000 K. All sdB stars are observed to have an approximately solar iron abundance whatever their original metallicity, implying overabundances by factors of up to 100. So should the 0.95 solar mass star. How its internal hydrodynamic properties on the main sequence may influence its fate on the HB is currently uncertain.Comment: Astronomische Nachrichten - Astronomical Notes (AN) papers presented at the Cool Stars 17 conference 2012 (AN 334, issue 1-2

Abundance anomalies in pre-main-sequence stars: Stellar evolution models with mass loss

The effects of atomic diffusion on internal and surface abundances of A and F pre-main-sequence stars with mass loss are studied in order to determine at what age the effects materialize, as well as to further understand the processes at play in HAeBe and young ApBp stars. Self-consistent stellar evolution models of 1.5 to 2.8Msun with atomic diffusion (including radiative accelerations) for all species within the OPAL opacity database were computed and compared to observations of HAeBe stars. Atomic diffusion in the presence of weak mass loss can explain the observed abundance anomalies of pre-main-sequence stars, as well as the presence of binary systems with metal rich primaries and chemically normal secondaries such as V380 Ori and HD72106. This is in contrast to turbulence models which do not allow for abundance anomalies to develop on the pre-main-sequence. The age at which anomalies can appear depends on stellar mass. For A and F stars, the effects of atomic diffusion can modify both the internal and surface abundances before the onset of the MS. The appearance of important surface abundance anomalies on the pre-main-sequence does not require mass loss, though the mass loss rate affects their amplitude. Observational tests are suggested to decipher the effects of mass loss from those of turbulent mixing. If abundance anomalies are confirmed in pre-main-sequence stars they would severely limit the role of turbulence in these stars.Comment: 9 pages, 6 figures, accepeted for publicatio

Alien Registration- Michaud, Hazel G. (Monticello, Aroostook County)

https://digitalmaine.com/alien_docs/33977/thumbnail.jp

Male music teachers and singing fathers: effects on and correlations with kindergarten children's singing abilities

Thesis (D.M.A.)--Boston UniversityThe purpose of this study was to discover the effects, if any, of baritone and falsetto singing models on kindergarten children's singing range development and pitchmatching abilities. An additional purpose was to determine if there is a relationship between the amount of singing that fathers do with and to their children in the home and those children's singing range development and pitch-matching abilities. I investigated the following questions: (a) What effect, if any, does a male music teacher's use/nonuse of falsetto have on kindergarten children's singing range development? (b) What effect, if any, does a male music teacher's use/nonuse of falsetto have on kindergarten children's pitch-matching abilities? (c) To what extent does the amount of singing that fathers do with and to their children in the home correlate with those children's singing range development? (d) To what extent does the amount of singing that fathers do with and to their children in the home correlate with those children's pitch-matching abilities? Participants were 66 kindergarten children in four intact classrooms who received music instruction for 30 minutes once each week for 20 weeks. Two classes (n = 29) experienced a baritone vocal model during music instruction, while two classes (n = 37) experienced a falsetto vocal model during music instruction. Parents completed a revised version of the HOMES questionnaire (Brand, 1985) at the outset of the study to provide information about the children's musical home life. Vocal range development was tested using the Singing Voice Development Measure (Rutkowski, 1996). I tested pitchmatching accuracy of sol-mi patterns in a call-and-response song. Results of a MANCOVA indicated no significant differences in either pitchmatching or vocal development between the two groups; however, the results of a chi-square test indicated significantly more children in the falsetto group had success in singing over the break in the head register on the SVDM pretest (p < .00) and SVDM posttest (p = .01). The results of the HOMES indicated that the amount of singing that fathers did with and to their children in the home had multiple significant (p < .05) positive correlations with the children's scores in both pitch-matching and singing range development pre-, mid-, and post-tests. Based on the results, I recommended that male elementary music teachers consider using their falsetto ranges when teaching kindergarten children to sing in their head registers. In addition, fathers should be encouraged to sing with their children because it appears that the amount of singing fathers do with and to their children in the home positively correlates with those children's singing abilities

Two-dimensional dilaton black holes

The two-dimensional CGHS model provides an interesting toy-model for the study of black hole evaporation. For this model, a quantum effective action, which incorporates Hawking radiation and backreaction, can be explicitly constructed. In this paper, we study a generalization of this effective action. In our extended model, it is possible to remove certain curvature singularities arising for the original theory. We also find that the flux of Hawking radiation is identical to that encountered in other two-dimensional models

Using Proprietary Databases to Overcome Data Suppression in Industry Cluster Analysis

Extension agents are frequently tasked with determining industry clusters that exist in a region to support economic development. However, data suppression issues recurrently prohibit a comprehensive understanding of heavily concentrated firms in a region, particularly in rural areas. This article discusses the use of North American Industry Classification System codes within the LexisNexis Academic database as a technique for locating data about specific firms and analyzing regional industry clusters. This approach provides a practical and cost-efficient method for Extension agents and other researchers and practitioners to identify clusters and gather firm information in small geographies throughout the United States