University, Diss., 2003--Bonn.

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This dissertation is a compilation of four separate studies under the umbrella of the Chemical Abundance of Stars in the Halo (CASH) Project. The overall goal of the CASH project is to gain a better understanding of the events and processes that occurred during the early universe that shaped the composition of the stars that we observe today. In order to do so, we have conducted a comprehensive study of the abundances of the oldest observable stars. These stars have preserved the chemical signature of the material from which they formed in their atmospheres. The old, metal-poor stars that make up the stellar halo thus provide a means to study the history of the universe. We will discuss the motivation for the project in Chapter 1, introducing the field of metal-poor halo stars and providing background about the processes that have contributed to the chemical make up of the stars. The first generation of stars that created much of the material from which these stars formed are discussed, along with the low-mass evolved stars that synthesized additional elements in their interiors that are also observed in metal-poor stars today. Utilizing so-called ``snapshot'' spectra obtained with the High Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory, we provide abundances for 262 stars over the sample. In Chapter 2, we present Robospect, a new code to automatically measure and deblend line equivalent widths for both absorption and emission spectra. We used this code to calculate equivalent width measurements, which provide the foundation of the analysis, from our spectra. We test the accuracy of these measurements against simulated spectra as well as manual equivalent width measurements of five stellar spectra over a range of signal-to-noise values and a set of long slit emission spectra. We find that Robospect accurately matches both the synthetic and manual measurements, with scatter consistent with the expectations based on the data quality and the results of Cayrel (1988). In Chapter 3, we present a comprehensive abundance analysis of 20 elements for 16 new low-metallicity stars from the CASH project. The abundances have been derived from both Hobby-Eberly Telescope High Resolution Spectrograph snapshot spectra (R ~15,000) and corresponding high-resolution (R~35,000) Magellan MIKE spectra. The stars span a metallicity range from [Fe/H] from -2.9 to -3.9, including four new stars with [Fe/H]<-3.7. These pilot sample stars are the most metal-poor ([Fe/H]≲-3.0) of the brightest stars included in CASH and are used to calibrate a newly-developed, automated stellar parameter and abundance determination pipeline. This code is used for the entire CASH snapshot sample. We find that the pipeline results are statistically identical for snapshot spectra when compared to a traditional, manual analysis from a high-resolution spectrum. We find four stars to be carbon-enhanced metal-poor (CEMP) stars, confirming the trend of increasing [C/Fe] abundance ratios with decreasing metallicity. Two of these objects can be classified as CEMP-no stars, adding to the growing number of these objects at [Fe/H]<-3. We also find four neutron-capture enhanced stars in the sample, one of which has [Eu/Fe] of 0.8 with clear r-process signatures. In Chapter 4, we present stellar parameters and abundances for the full CASH sample of 263 metal-poor halo star candidates derived from snapshot spectra obtained with the High Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory. We determine abundance statistics and trends for 16 elements over the full sample. We identify astrophysically-interesting stars that merit further investigation, including carbon-enhanced metal-poor stars, neutron-capture element enhanced stars, and extremely metal-poor stars. We note one Li giant with a unique abundance pattern. In Chapter~5 we present a detailed abundance analysis of 23 elements for a newly discovered carbon-enhanced metal-poor (CEMP) star, HE 0414-0343, from the CASH sample. Its spectroscopic stellar parameters are T_eff=4863 ,K, log g=1.25, ξ=20 km/s, and [Fe/H]=-2.24. Radial velocity measurements covering seven years indicate HE 0414-0343 to be a binary. HE 0414-0343 has [C/Fe]=1.44 and is strongly enhanced in neutron-capture elements but its abundances cannot be reproduced by a solar-type s-process pattern alone. It could be classified as ``CEMP-r/s'' star but we find that no r-process component is required as explanation of this and other similar stars classified as ``CEMP-s'' and ``CEMP-r/s'' stars. Rather, based on comparisons with AGB star nucleosynthesis models, we suggest a new physically-motivated classification scheme, especially for the still poorly-understood ``CEMP-r/s'' stars. Importantly, it reflects the continuous transition between these so-far distinctly treated subgroups: CEMP-sA, CEMP-sB, and CEMP-sC. The [Y/Ba] ratio parameterizes the classification and can thus be used to classify any future such stars. Possible causes for the transition include the number of thermal pulses the AGB companion underwent and the effect of different AGB star masses on their nucleosynthetic yields. We then speculate that higher AGB masses may explain ``CEMP-r/s'' or now CEMP-sB and CEMP-sC stars, whereas less massive AGB stars would account for ``CEMP-s'' or CEMP-sA stars. Based on a limited set of AGB models, we suggest the abundance signature of HE~0414$-$0343 to have come from a >1.3 M_⊙ mass AGB star and a late-time mass transfer, thereby making it a CEMP-sC star. Finally, in Chapter 6, we summarize our results and provide future directions for the project. / text

The confirmation of a globular cluster (GC) in the recently discovered ultrafaint galaxy Eridanus II (Eri II) motivated us to examine the question posed in the title. After estimating the halo mass of Eri II using a published stellar mass-halo mass relation, the one GC in this galaxy supports extending the relationship between the number of GCs hosted by a galaxy and the galaxy's total mass about two orders of magnitude in stellar mass below the previous limit. For this empirically determined specific frequency of between 0.06 and 0.39 GCs per 10(9)M(circle dot) of total mass, the surviving Milky Way (MW) subhalos with masses smaller than 10(10)M(circle dot) could host as many as 5-31 GCs, broadly consistent with the actual population of outer halo MW GCs, although matching the radial distribution in detail remains a challenge. Using a subhalo mass function from published high-resolution numerical simulations and a Poissonian model for populating those halos with the aforementioned empirically constrained frequency, we find that about 90% of these GCs lie in lower-mass subhalos than that of Eri II. From what we know about the stellar mass-halo mass function, the subhalo mass function, and the mass-normalized GC specific frequency, we conclude that some of the MW's outer halo GCs are likely to be hosted by undetected subhalos with extremely modest stellar populations.

Thesis advisor: Ana M. Martínez Alemán / Through a qualitative case study of Butler University, this study seeks to understand how high-profile athletic success—in this instance, a Cinderella run in the NCAA Division I men’s basketball tournament—can be leveraged to develop other institutional functions and elevate the profile of the university as a whole. The story of Butler’s investment in men’s basketball, culminating in two successive trips to the Final Four in 2010 and 2011, spans nearly three decades and offers an extreme yet instructive case of the potential synergy between a serious academic institution and a big-time college sports program. Through interviews with faculty and administrators, document analysis, and field observations on Butler’s campus, a picture emerges of the Cinderella story as a university resource that can be developed and managed through the decision-making of administrators in a variety of offices, including admissions, advancement, athletics, and marketing and communications. At Butler, the narrative begins in 1989 with the intentional decision to build men’s basketball into a flagship program for the institution, peaks with the twin Final Four appearances, and then consists of efforts to leverage this success as part of the university’s pursuit of a national profile after a long history as a regional institution. / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Lynch School of Education. / Discipline: Educational Leadership and Higher Education.

Northern Norrbotten County is one of the three major ore producing districts in Sweden. Based on the predominance of epigenetic Cu-Au and Fe-oxide mineralization this region is regarded as a typical IOCG province. The massive to layered Viscaria Cu-deposit is proposed to be a VMS deposit of Besshi-type and is unique in deposit type of the region. The volcaniclastic rocks of the Viscaria Formation hosting the Viscaria deposit belong to the rift related Kiruna Greenstone Group. The Viscaria deposit consists of three stratiform-stratabound mineralized zones: A-, B- and D-zone. Sulphide mineralization of the D-zone differs in structural features, host rock, mineralization style and Fe-oxide dominance over Cu-sulphides compared to the main Cu-ore in the A-zone. These differences between A- and D-zone mineralization styles raise the subject that the D-zone could be of a different origin.   The Kiruna area is mainly covered by glacial-till, which contributes to limited bedrock exposure. This becomes a challenge when exploring for new deposits and highlights the importance of good geological knowledge obtained from existing deposits to carry through successful exploration programs. The objective of this study is to characterize the Fe-Cu-occurrence and the associated alteration halo of the Viscaria D-zone. Alteration halos can reach several kilometres away from the main ore zone and provides mineralogical and chemical signatures that extend the target area significantly in exploration for new deposits. Detailed core logging, optical microscopic studies, lithogeochemistry and electron microprobe analyses was utilized to contribute to a better genetic understanding of the D-zone and the associated hanging wall and footwall alteration features. The study shows that the main ore minerals of the D-zone consist of magnetite and chalcopyrite, and minor pyrite and hematite. The major alteration minerals associated with mineralization are calcite, actinolite/tremolite, epidote, chlorite and also biotite and scapolite in the hanging wall. The most prominent potential ore vector is calcite veins and biotite, as the abundance increase towards the D-zone. D-zone are further characterised by low REE concentrations, similarly to the calcic-dolomite host. The study also shows that the alteration halo of the D-zone is different in the hanging wall compared to the footwall, which is confirmed by the lithogeochemistry and mineral chemistry. The footwall is characterized by spilitization and chlorite alteration. The lithogeochemistry of the D-zone and the hanging wall reveals element mobility of Mg, Ba, Fe, Na, K, Cu and Zn. Mineral chemistry of epidote, amphibole and chlorite shows chemical changes in Fe/Al- and Mg/Fe-ratios. According to the result of this thesis and earlier studies, the D-zone mineralization is suggested to be part of the VMS system forming the stratigraphically above laying A-zone of the Viscaria Cu-deposit.

The Hobby-Eberly Telescope Chemical Abundances of Stars in the Halo (CASH) project aims to characterize the nature of the early universe through the study of metal-poor stars in the stellar halo of the galaxy. Once completed, this will be the largest set of abundances determined for metal-poor stars from high resolution spectra. In this paper, we present chemical abundances and trends of eleven elements for the first ~80 stars of the ~500 star study. These 80 stars serve as a pilot sample to test the automated stellar parameter and abundance determination pipeline newly developed for the CASH project called CASHCODE. Among the pilot sample, two stars with [Fe/H]<-3.5 were discovered and their abundance analysis is discussed. / text

The current study was conducted to investigate whether gender and physical attractiveness of face primes had any effect on subsequent categorization of weapons and non-weapons by participants. In Study 1 participants were required to rate a set of face photos of men and women on their level of at-tractiveness and also how threatening they perceived them to be. These photos were used for Study 2 as primes paired with weapons and non-weapons. One hundred and ten University of Canterbury students were required to categorise weapons from non-weapons after primed faces appeared on a computer screen. Adapted from the ‘shooter paradigm’ and priming studies, this aimed to discover participant’s stereotypes when threat is involved. Specifically, it aimed to assess people’s susceptibility to perceive a non-threatening item as a threat. Three possible theories are presented to explain the findings – the halo effect, the evolutionary intra-sexual competition theory, and the arousal theory. The results of study 1 indicated that there is a negative correlation between physical attractiveness and threat, such that as a target’s physical attractiveness increases their perceived level of threat decreases, suggesting the existence of an overall halo effect (attractive people are non-threatening). The results of study 2 revealed an impact of female primes (in particular attractive female primes) on males’ misclassification of non-weapons. There was no effect found of the primes on females’ classifications. An arousal theory is used to explain this differential response. The results are discussed in terms of implications for the real-world and limitations of the study are outlined and suggestions are made regarding future research.

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Introduction: There are no validated strategies in the teaching of ultrasound as a diagnostic tool in undergraduate medicine students. Given the role that ultrasound plays in the diagnostic capacity of any clinician is currently undeniable, a teaching method is proposed based on the demonstration of the association between the histopathology of a large vessel vasculitis and the characteristic ultrasound finding, known as the «halo sign». Methods: The teaching strategy was imparted by means of a 10-minute video presentation. Twenty-one final-year students from a single medical school participated in a concordance study and a validation test, identifying images corresponding to the halo sign in 120 different cases. The overall sensitivity, specificity and likelihood ratio of the students were also determined. Results: The overall concordance test had a kappa coefficient of 0.749 (SD: 0.11). The kappa concordance was 0.76 with dynamic images, and 0.84 with cross-sectional slices. The overall sensitivity was 89.7%, and the positive predictive value was 92.3%. The likelihood ratio achieved was 7.28. Conclusions: It has been shown that the application of this pedagogical method is useful in teaching the identification of an ultrasound sign to medical students. This study also suggests conditions that could be useful to improve between-observer agreement in both teaching scenarios and multiple observer scientific studies. / Revisión por pares