The field horizontal-branch star HD 109995: New results with coadded ultraviolet and optical region spectra

A comprehensive ultraviolet and optical region abundance analysis of the field horizontal branch Population 2 A-type star HD 109995 is described. Coaddition of IUE high dispersion images and DAO 6.5 A/mm IIaO spectrograms improved the signal-to-noise ratio of the data. We have identified ultraviolet lines whose analysis will provide more complete and accurate elemental abundances than those obtained from optical region spectra alone. A preliminary elemental abundance analysis of the optical region shows that log Z/Z (solar) approx. = -2. A first attempt to synthesize two Fe 2 ultraviolet resonance lines yields an iron abundance a few tenths of a deg higher than the average obtained from optical region Fe 2 lines

What? How? Why? Resource Use by Michigan Two-Year College Instructors When Planning and Teaching the Fundamental Theorem of Calulus

This dissertation examines the resources that two-year college instructors use to aide their teaching. In particular, this dissertation is an investigation into the resources used by two-year college calculus instructors in Michigan when they plan and teach the Fundamental Theorem of Calculus (FTC), how they use those resources and why they use them. Resources are broadly defined as assets that instructors access that impact their planning and instruction. While there are many resources available for teaching the FTC, they are often minimally used. The FTC connects the two major calculus concepts of differentiation and integration, yet it is difficult for students to understand the significance of the theorem. Traditionally, the FTC is presented as two theorems, in one section of one chapter of a textbook. One theorem describes the inverse relationship between differentiation and integration, and the other theorem explains how to calculate a definite integral. Theoretical underpinnings for this study come from documentational and instrumental genesis, as articulated by Gueudet and Trouche (2009). This theory articulates the dual understanding of how instructors use resources and how resources affect instructors. The study uses a mixed method design with three levels of data collection: a survey of all community college calculus instructors at all the Michigan community colleges; 14 interviews with instructors, selected to represent a variety of experience levels; and two classroom observations of instructors who identified the FTC as important and identified themselves as comfortable teaching it. Findings from this dissertation indicated that most instructors use the textbook for planning and homework, and use their personal background and student feedback when teaching a lesson on the FTC. Despite the calculus reform movement in the 1980s that encouraged teachers to incorporate technology into their classroom, and the availability of technologies that would help explain concepts vital to understanding the FTC, this study found that the theorem is often presented without technology. An examination of instructor descriptions of the importance of the FTC revealed that instructors tended to consider the FTC as two disconnected theorems, similar to how it was presented in the textbooks. Instructors also allocated the same amount of time to the FTC as they did to other sections of the textbook. One implication from these findings is that if instructors wished to emphasize the FTC in their calculus classes by spending more time on it, the resources that they use may be inadequate. This dissertation contributes to research that focuses more broadly on higher education mathematics curriculum research.PHDEducational StudiesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147597/1/lleckron_1.pd

Paper Session II-B - Modernizing Hubble Space Telescope for the Next Millennium

In December 1993, NASA carried out an extremely ambitious mission to Hubble Space Telescope (HST) to correct the spherical aberration causing HST’s blurred vision. The unqualified success of this mission proved that we could service HST safely and effectively. In February 1997, in the first of three servicing missions to upgrade HST’s science capability, astronauts returned to HST and fitted the telescope with a near-infrared camera (NICMOS) and a much more powerful spectrograph (STIS). In 1999, a crew will again visit HST to install the Advanced Camera for Surveys (ACS), a high resolution, wide field camera with 10 times the discovery efficiency of HST’s current Wide Field and Planetary Camera (WFPC2). Finally, in 2002, HST will be serviced and upgraded one last time, allowing it to remain healthy for the duration of its mission, which is expected to last until 2010. During this last servicing mission, we will fit HST with its most sensitive spectrograph, the Cosmic Origins Spectrometer (COS). We are also considering the possibility of replacing the aging WFPC2 on this final mission with a new, low cost, highly sensitive wide field camera (WFC-3), created from components of the first WFPC1, returned from orbit in 1993, and from spare CCD detectors from the ACS

The Application of Biomechanical Technology in Sports

Technology in biomechanics encompasses eight major categories: artificial optical devices, anthropometry, timing devices, electrogoniometry, electromyography, dynamometry, inertial tracking systems, and modeling and simulation. As technology improves and becomes more accessible to the general population, it becomes easier to implement biomechanical technology into sports. For each area of focus, biomechanical technology has numerous points of current application or potential application. This application has benefit in injury prevention, technique improvement, rule enforcement, performance optimization, overall health and condition analysis, sports timing, and product development and testing. This thesis examines each area in turn as well as the various tools implemented in order to provide an overview of how athletes, coaches, and trainers can benefit from their application

Stellar model atmospheres with magnetic line blanketing

Model atmospheres of A and B stars are computed taking into account magnetic line blanketing. These calculations are based on the new stellar model atmosphere code LLModels which implements direct treatment of the opacities due to the bound-bound transitions and ensures an accurate and detailed description of the line absorption. The anomalous Zeeman effect was calculated for the field strengths between 1 and 40 kG and a field vector perpendicular to the line of sight. The model structure, high-resolution energy distribution, photometric colors, metallic line spectra and the hydrogen Balmer line profiles are computed for magnetic stars with different metallicities and are discussed with respect to those of non-magnetic reference models. The magnetically enhanced line blanketing changes the atmospheric structure and leads to a redistribution of energy in the stellar spectrum. The most noticeable feature in the optical region is the appearance of the 5200 A depression. However, this effect is prominent only in cool A stars and disappears for higher effective temperatures. The presence of a magnetic field produces opposite variation of the flux distribution in the optical and UV region. A deficiency of the UV flux is found for the whole range of considered effective temperatures, whereas the ``null wavelength'' where flux remains unchanged shifts towards the shorter wavelengths for higher temperatures.Comment: accepted by Astronomy & Astrophysic

Despite rising inequality, Mayors are still focusing on economic development – not redistribution – to help the poor

Some studies have shown that addressing income inequality is gaining in popularity. Michelle Atherton and Wesley Leckrone explore whether concern for the poor is an item on the agendas of big cities. Their analysis of mayors’ State of the City (SOTC) speeches shows that attention to redistributive policy options is rare regardless of the demographic or ideological characteristics of a city. The past trend of focusing on economic development, and therefore growth, is still the predominant focus of US mayors. This is especially the case for poorer and more conservative cities

Paper Session II-A - Hubble Space Telescope: The Image Restored

Since the first servicing mission to Hubble Space Telescope (HST), astronomy has entered a new golden age. This paper will serve to give a small set of examples of the new imagery and the unexpected discoveries that have been made using the Wide Field and Planetary Camera 2 (WFPC2) built by NASA’s Jet propulsion Laboratory. In addition, using these examples, the extrapolation to “what’s ahead” will be discussed

In US COVID-19 responses, party polarization has trumped cooperative federalism

From the beginnings of the COVID-19 pandemic in early 2020, the administration of President Trump left much of the task of responding to COVID-19 to the states, largely eschewing cooperative measures between the federal and state and local governments. John Kincaid and J. Wesley Leckrone write that while some commentators have lamented that there was not a more centralized response, cooperation between the federal and state and local governments was restricted by partisan polarization and a president ideologically opposed to many COVID-19 mitigation measures

Beyond the iron group: heavy metals in hot subdwarfs

We report the discovery of strong photospheric resonance lines of Ga III, Ge IV, Sn IV and Pb IV in the UV spectra of more than two dozen sdB and sdOB stars at temperatures ranging from 22000 K to 40000 K. Lines of other heavy elements are also detected, however in these cases more atomic data are needed. Based on these discoveries, we present a hypothesis to explain the apparent lack of silicon in sdB stars hotter than ~32000 K. The existence of triply ionised Ge, Sn, and Pb suggests that rather than silicon sinking deep into the photosphere, it is removed from the star in a fractionated stellar wind. This hypothesis provides a challenge to diffusion models of sdB stars.Comment: 5 pages, 3 figures, to appear in A&A Letter