Cry to dream again

Thesis (M.A.)--University of Kansas, English, 1966

Radial Velocities of Newly Discovered Globular Clusters in NGC 5128

We present radial velocity measurements for 74 globular clusters (GCs) in the nearby giant elliptical NGC 5128, of which 31 are newly discovered clusters. All the GC candidates were taken from the list of possible new clusters given in the Harris, Harris, & Geisler (2004) photometric survey. In addition to the newly confirmed clusters, we identified 24 definite foreground stars and 31 probable background galaxies. From a combined list of 299 known GCs in NGC 5128 with measured radial velocities and metallicity-sensitive (C - T_1) photometric indices, we construct a new metallicity distribution function (MDF) for the cluster system. The MDF shows an approximately bimodal form, with centroids at [Fe/H] = -1.46 and -0.53, and with nearly equal numbers of metal-poor and metal-rich clusters in the two modes. However, there are many intermediate-color clusters in the distribution, and the fainter clusters tend to have a higher proportion of red clusters. These features of the MDF may indicate a widespread age range within the cluster system as well as an intrinsically broad metallicity spread.Comment: 10 pages, 7 figures, 4 tables - accepted in Astronomical Journa

NGC 5128: The Giant Beneath

I review what we have learned about the old stellar population of NGC 5128, the only large E galaxy close enough that we can currently observe individual stars as faint as the horizontal branch. Although its galaxy type is still a matter of debate for some, the uncertainties over distance are now largely resolved; comparison of five stellar distance indicators gives d=3.8 +- 0.1 Mpc. The globular cluster system, which was once perplexingly invisible, is now known to be predominantly old with a substantial metal-rich component. The GCS total population and luminosity function are normal and the clusters follow the same fundamental plane relation as those in the Milky Way and M31. Finally, the halo out to at least ~7r_{eff} is dominated by metal-rich stars which are also predominantly old, with age and metallicity tantalizingly similar to the majority of globular clusters.Comment: PASA in pres

The History of Desegregation and the Theory of Student Choice

Diversity of the student population is legislated and affects recruitment strategies at colleges and university. There is much legal history bringing administrators to the current position. Blending the history of desegregation and the resultant legal situation with the Theory of Student Choice is important to ensure enrollment targets are met. Student choice factors are instrumental in determining which college a student will attend. Understanding which factors influence white students to attend HBCUs, and black students to attend TWIs, is important for administrators and will help them ensure desegregation structural diversity mandates are met. This paper reviews the legal history and the Theory of Student Choice as a beginning point to assist Institutional policy makers, and defines the need for future efforts

Directives and Academics: educational developers, technology and the right support

There can be ‘an army of people involved in the development of academics as teachers’ (Ling & CADAC, 2009) and the role of Educational Developers with technological expertise is vital to the uptake and creative use of educational technologies in learning contexts (Oliver, 2005). Even so, technology plays only a part in the teaching and learning experience and must be underpinned with pedagogical wherewithal. At Victoria University (VU) in Melbourne, a new VU Agenda expects the university to be known for educational programmes ‘that maximise opportunities for blended and eLearning’. This discussion examines the support available to staff using technologies for teaching. The discussion covers two examples from different faculties where teaching staff have needed to comply with Faculty or School directives to use particular university-supported technologies (Lectopia and GradeMark). The comments about staff uptake of technologies draw on general themes from evaluations administered in each faculty to gauge the effectiveness of the technologies for teaching and to identify further professional development needs. Unsurprisingly, the findings show that, without intensive and timely support tailored to the specific requirements of academics, without academics having both an understanding of the reason for the mandating of a technology as well as an ability to influence that uptake, academics are likely to find ways to resist authoritarian directives. The danger of encouraging academics’ uptake of educational technologies without broader educational development support to encourage good teaching practices that integrate technology and good curriculum design became clear from the dat

Rainfall Estimations From Geosynchronous Satellite Imagry

A method to estimate rainfall from visible geosynchronous satellite images is outlined. The two component relationships, derived from ATS-3 and WSR-57 radar data, are discussed. Calculations are made on two days with this method and compared with ground truth rainfall. Satellite estimates on both days are within a factor of two of ground truth. Sources of error in the component relationships are ennumerated. Several planned refinements, such as stratification of the data by synoptic condition and origin of convection, are presented

Signatures of accretion events in the halos of early-type galaxies from comparing PNe and GCs kinematics

We have compared the halo kinematics traced by globular clusters (GCs) and planetary nebulae (PNe) for two elliptical galaxies in the Fornax and Virgo clusters NGC 1399 and NGC 4649, and for the merger remnant NGC 5128 (Centaurus A). We find differences in the rotational properties of the PN, red GC, and blue GC systems in all these three galaxies. NGC 1399 PNe and GCs show line of sight velocity distributions in specific regions that are significantly different, based on Kolmogorov-Smirnov tests. The PN system shows multi-spin components, with nearly opposite direction of rotation in the inner and the outer parts. The GCs velocity field is not point-symmetric in the outer regions of the galaxy, indicating that the system has not reached dynamical equilibrium yet. In NGC 4649 PNe, red and blue GCs have different rotation axes and rotational velocities. Finally, in NGC 5128 both PNe and GCs deviate from equilibrium in the outer regions of the galaxy, and in the inner regions the PN system is rotationally supported, whereas the GC system is dominated by velocity dispersion. The observed different kinematic properties, including deviations from point-symmetry, between PNe and GCs suggest that these systems are accreted at different times by the host galaxy, and the most recent accretion took place only few Gyr ago.We discuss two scenarios which may explain some of these differences: i) tidal stripping of loosely-bound GCs, and ii) multiple accretion of low luminosity and dwarf galaxies. Because these two mechanisms affect mostly the GC system, differences with the PNe kinematics can be expected.Comment: 14 pages, 13 figures, Accepted for publication in MNRAS. This new version contains an improved analysis, which includes the study of point-symmetry in the velocity fields and its implications for dynamical equilibriu

Simulation of hurricane response to suppression of warm rain by sub-micron aerosols

The feasibility of hurricane modification was investigated for hurricane Katrina using the Weather Research and Forecasting Model (WRF). The possible impact of seeding of clouds with submicron cloud condensation nuclei (CCN) on hurricane structure and intensity as measured by nearly halving of the area covered by hurricane force winds was simulated by "turning–off" warm rain formation in the clouds at Katrina's periphery (where wind speeds were less than 22 m s<sup>−1</sup>). This simplification of the simulation of aerosol effects is aimed at evaluating the largest possible response. This resulted in the weakening of the hurricane surface winds compared to the "non-seeded" simulated storm during the first 24 h within the entire tropical cyclone (TC) area compared to a control simulation without warm rain suppression. Later, the seeding-induced evaporative cooling at the TC periphery led to a shrinking of the eye and hence to some increase in the wind within the small central area of the TC. Yet, the overall strength of the hurricane, as defined by the area covered by hurricane force winds, decreased in response to the suppressed warm rain at the periphery, as measured by a 25% reduction in the radius of hurricane force winds. In a simulation with warm rain suppression throughout the hurricane, the radius of the hurricane force winds was reduced by more than 42%, and although the diameter of the eye shrunk even further the maximum winds weakened. This shows that the main mechanism by which suppressing warm rain weakens the TC is the low level evaporative cooling of the un-precipitated cloud drops and the added cooling due to melting of precipitation that falls from above

Status and Habitat Characteristics of the Saltmarsh Topminnow, Fundulus jenkinsi (Evermann) in Eastern Mississippi and Western Alabama Coastal Bayous

The saltmarsh topminnow, Fundulus jenkinsi (Evermann, 1892), occurs sporadically along the northern Gulf of Mexico and appears to prefer Spartina habitat. Throughout its range, it is considered rare or threatened and has been placed on the US Federal Register\u27s List of Candidate Species. In order to determine the status and habitat characteristics of this species, we examined collections from 1985-1986, 1996, 1999, and 2001 from eastern Mississippi and western Alabama. We report on 868 F. jenkinsi collected in 82 locations using 414 seine hauls and 420 Breder traps over 40 dates. Results using all collections indicated F. jenkinsi is not as abundant as other fundulids in this area but is more abundant than previously thought. We also documented the first records for this species from the Pascagoula River drainage. For the Breder trap collections only, a stepwise linear regression indicated that water temperature and salinity explained 39.7% of the variance in log10 (mean CPUE + 0.5) over the time of this study and this relationship was significant (ANOVA, F3.59 = 13.95, P \u3c 0.001 ). The equation log10 (mean CPUE + 0.5) = 1.623 - 0.0150 (salinity) + 0.77 (depth) - 0.0584 (water temperature) indicated that mean CPUE of F. jenkinsiwas higher when salinity and water temperature were lower. Using bag seine and Breder trap data, this species was most abundant (90.7% of total) in salinities ≤ 12‰ while being mainly collected in water depths near 0.5 m and water temperatures ≥ 20.0°C. We feel the use of sampling gear designed to collect resident marsh fishes is imperative and use of other gear types and/or variation in annual rainfall and the subsequent extent and patchiness of low salinity salt marsh area from year to year may explain why this species appears rare or absent in most fish studies of the northern Gulf of Mexico. Because of its distribution in low-salinity bayou habitats, this small fundulid will probably be continually placed in situations where the habitat will be impacted due to development

The Kinematics of the Globular Cluster System of NGC 5128 with a New, Large Sample of Radial Velocity Measurements

New radial velocity measurements for previously known and newly confirmed globular clusters (GCs) in the nearby massive galaxy NGC 5128 are presented. We have obtained spectroscopy from LDSS-2/Magellan, VIMOS/VLT, and Hydra/CTIO from which we have measured the radial velocities of 218 known, and identified 155 new, GCs. The current sample of confirmed GCs in NGC 5128 is now 605 with 564 of these having radial velocity measurements. We have performed a new kinematic analysis of the GC system that extends out to 45 arcmin in galactocentric radius. We have examined the systemic velocity, projected rotation amplitude and axis, and the projected velocity dispersion of the GCs as functions of galactocentric distance and metallicity. Our results indicate that the metal-poor GCs have a very mild rotation signature of (26 pm 15) km/s. The metal-rich GCs are rotating with a higher, though still small signature of (43 pm 15) km/s around the isophotal major axis of NGC 5128 within 15 arcmin. Their velocity dispersions are consistent within the uncertainties and the profiles appear flat or declining within 20 arcmin. We note the small sample of metal-rich GCs with ages less than 5 Gyr in the literature appear to have different kinematic properties than the old, metal-rich GC subpopulation. The mass and mass-to-light ratios have also been estimated using the GCs as tracer particles for NGC 5128. Out to a distance of 20 arcmin, we have obtained a mass of (5.9 pm 2.0) x 10^(11) M_(sun) and a mass-to-light ratio in the B-band of 16 M_(sun)/L_(B,sun). Combined with previous work on the ages and metallicities of its GCs, as well as properties of its stellar halo, our findings suggest NGC 5128 formed via hierarchical merging over other methods of formation, such as major merging at late times.Comment: Accepted for The Astronomical Journal, 14 pages plus 12 figures and 7 table