4,427 research outputs found

    Oxygen and Sodium Abundances in M13 (NGC 6205) Giants: Linking Globular Cluster Formation Scenarios, Deep Mixing, and Post-RGB Evolution

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    We present O, Na, and Fe abundances, as well as radial velocities, for 113 red giant branch (RGB) and asymptotic giant branch (AGB) stars in the globular cluster M13. The abundances and velocities are based on spectra obtained with the WIYN-Hydra spectrograph, and the observations range in luminosity from the horizontal branch (HB) to RGB-tip. The results are examined in the context of recent globular cluster formation scenarios. We find that M13 exhibits many key characteristics that suggest its formation and chemical enrichment are well-described by current models. Some of these observations include: the central concentration of O-poor stars, the notable decrease in [O/Fe] (but small increase in [Na/Fe]) with increasing luminosity that affects primarily the "extreme" population, the small fraction of stars with halo-like composition, and the paucity of O-poor AGB stars. In agreement with recent work, we conclude that the most O-poor M13 giants are likely He-enriched and that most (all?) O-poor RGB stars evolve to become extreme HB and AGB-manqu\'e stars. In contrast, the "primordial" and "intermediate" population stars appear to experience standard HB and AGB evolution.Comment: Accepted for publication in The Astrophysical Journal Letters. 18 pages; 3 figures; 1 tabl

    The Development of a Quality Scale to Measure the Impact of Quality on Supermarket Fruit Demand

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    This research examines how fluctuations in quality affect consumer expenditures for fresh fruit at the retail level. This paper examines how consumersÂ’' purchasing behaviors react to changes in fresh fruit quality by quantifying quality characteristics based on weekly observations. A four-point scale was created and used to quantify four different quality characteristics: bruising, markings, brilliance, and maturity. A non-linear Almost Ideal Demand System was used to model the share equations for Gala apples, Fuji apples, Red Delicious apples, other sweet apples, tart apples, pears, bananas, and oranges. Seventy-nine weeks of data on weekly store sales were collected from two grocery stores in the Portland, Oregon metropolitan area. Results from the quality measures are provided and discussed. Suggestions are made for modifications to the quality measures to improve the modeling results of future fruit-demand studies.Demand and Price Analysis,

    Collecting Store-Level Data on Retail Supermarket Sales

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    Primary data-collection methods have been understood and studied to a great degree. For example, volumes can be written on the proper way to conduct a survey-based study. However, the process of collecting data from a retail establishment is not as well documented. This paper covers the tools and strategies used to collect weekly data in a retail environment and makes some suggestions for future researchers so that they may avoid similar problems that occurred during the data collection and entry process.Agribusiness,

    Marketing-Management Impacts on Produce Sales

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    Produce departments are important to the profitability and competitiveness of grocery stores. Understanding how variables beyond price and seasonality impact the demand and ultimately sales for produce is vital. This study finds display size and the use of multiple displays to be the most powerful tools (after price) that produce managers have available to them, but only with the right products. Also, point-of-purchase signage is found to have limited impact. These findings are based on the estimation of a demand system of fruits with prices, advertising size and location, display size (including multiple displays), and product origin among the explanatory variables.Agribusiness, Marketing,

    Adaptations: Expressions of sexuality, the law, and workplace sexual harassment [abstract]

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    Abstract only availableSexual harassment law within the US is unable to accurately handle the real life experiences of women, especially the workplace experience. Feminist theorists have suggested many options to deal with the laws' inefficiencies; however, many of the theories are confronted with modern obstacles upon application. In order to allow women to exist in the workplace while eliminating sexual harassment a balance between the workplace environment and the expression of feminine sexuality must be achieved. To strike this balance requires a redefinition of gender to breakout of the widely accepted false gender dichotomy that exists. In order for redefinition to take place theorists have suggested the necessity for a space in which the process can take place. Currently this space is imaginary. Overcoming the modern obstacles offers the possibility of a justice system that is more able to handle the variation of sexual harassment that faces women in the workplace. This project sets aside the redefinition aspect and moves into an area that involves the adaptation and application of the existing laws to address the varied experience of workplace sexual harassment. Through an analytical reading of feminist theoretical debates, case law, and court opinions multiple unaddressed issues have been identified within the law and the surrounding debates. Using current laws to work within the modern justice system can allow women to be heard and their experiences of workplace sexual harassment to be accurately taken up by the courts.McNair Scholars Progra

    Characterization of iodine particles with Volatilization-Humidification Tandem Differential Mobility Analyser (VH-TDMA), Raman and SEM techniques

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    Particles formed upon photo-oxidation of CH2I2 and particles of I2O5 and HIO3 have been studied using a Volatilisation and Humidification Tandem Differential Mobility Analyser (VH-TDMA) system. Volatilization and hygroscopic behaviour have been investigated as function of temperature (from 25 to 400 degrees Celsius), humidity (RH from 80 to 98%), initial aerosol sizes (from 27 to 100 nm mobility diameter) and in nitrogen or air as the sheath gasses. The volatility behaviour of particles formed upon photo-oxidation of CH2I2 is more similar to that of HIO3 particles in a filtered sheath air than in nitrogen, with the particle shrinkage occurring at 190 degrees Celsius and accompanied by hygroscopic growth. Despite its high solubility, HIO3 was found not to be hygroscopic at room temperature with no significant growth displayed until the thermodenuder temperature reached 200 degrees Celsius or above when the particles have transformed into I2O5. Diiodopentaoxide (I2O5) particles exhibit relatively low hygroscopic growth factors of 1.2-2 in the humidity range investigated. Scanning Electron Microscopy (SEM) of particles formed upon photo-oxidation of CH2I2 shows that their primary elemental components were iodine and oxygen in a stoichiometric ratio of approximately 1:2 with 10% error. Both Raman spectra and SEM show poor crystallinity for all the aerosols produced

    Detailed Abundances for a Large Sample of Giant Stars in the Globular Cluster 47 Tucanae (NGC 104)

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    47 Tuc is an ideal target to study chemical evolution and GC formation in massive more metal-rich GCs since is the closest, massive GC. We present chemical abundances for O, Na, Al, Si, Ca, Ti, Fe, Ni, La, and Eu in 164 red giant branch (RGB) stars in the massive globular cluster 47 Tuc using spectra obtained with both the Hydra multi-fiber spectrograph at the Blanco 4-m telescope and the FLAMES multi-object spectrograph at the Very Large Telescope. We find an average [Fe/H]=--0.79±\pm0.09 dex, consistent with literature values, as well as over-abundances of alpha-elements ([\alpha/\mbox{Fe}]\sim0.3 dex). The n-capture process elements indicate that 47 Tuc is r-process dominated ([Eu/La]=+0.24), and the light elements O, Na, and Al exhibit star-to-star variations. The Na-O anti-correlation, a signature typically seen in Galactic globular clusters, is present in 47 Tuc, and extends to include a small number of stars with [O/Fe] \sim\,--0.5. Additionally, the [O/Na] ratios of our sample reveal that the cluster stars can be separated into three distinct populations. A KS-test demonstrates that the O-poor/Na-rich stars are more centrally concentrated than the O-rich/Na-poor stars. The observed number and radial distribution of 47 Tuc's stellar populations, as distinguished by their light element composition, agrees closely with the results obtained from photometric data. We do not find evidence supporting a strong Na-Al correlation in 47 Tuc, which is consistent with current models of AGB nucleosynthesis yields.Comment: Accepted for publication in The Astrophysical Journa

    Space Station Centrifuge: A Requirement for Life Science Research

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    A centrifuge with the largest diameter that can be accommodated on Space Station Freedom is required to conduct life science research in the microgravity environment of space. (This was one of the findings of a group of life scientists convened at the University of California, Davis, by Ames Research Center.) The centrifuge will be used as a research tool to understand how gravity affects biological processes; to provide an on-orbit one-g control; and to assess the efficacy of using artificial gravity to counteract the deleterious biological effect of space flight. The rationale for the recommendation and examples of using ground-based centrifugation for animal and plant acceleration studies are presented. Included are four appendixes and an extensive bibliography of hypergravity studies
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