The Evolution of X-Ray Clusters in a Cold Plus Hot Dark Matter Universe

We present the first self-consistently computed results on the evolution of X-ray properties of galaxy clusters in a Cold + Hot Dark Matter (CHDM) model. We have performed a hydrodynamic plus N-body simulation for the COBE-compatible CHDM model with standard mass components: Omega(hot) = 0.3, Omega(cold) = 0.6 and Omega(baryon) = 0.1 (h = 0.5). In contrast with the CDM model, which fails to reproduce the observed temperature distribution function dN/dT (Bryan et al. 1994b), the CHDM model fits the observational dN/dT quite well. Our results on X-ray luminosity are less firm but even more intriguing. We find that the resulting X-ray luminosity functions at redshifts z = 0.0, 0.2, 0.4, 0.7 are well fit by observations, where they overlap. The fact that both temperatures and luminosities provide a reasonable fit to the available observational data indicates that, unless we are missing some essential physics, there is neither room nor need for a large fraction of gas in rich clusters: 10% (or less) in baryons is sufficient to explain their X-ray properties. We also see a tight correlation between X-ray luminosity and gas temperature.Comment: 11 pages, 3 figures uuencoded postscript file, (92 kb), accepted for publication in Astrophysical Journal Letters. Also available via anonymous ftp at zeus.ncsa.uiuc.edu in gc3/publications/gc3005, LCA01

Integrating University Value Messages into the Basic Communication Course: Implications for Student Recall and Adjustment to College

This study investigated the effects of integrating a university’s core value messages into the curriculum of a basic communication course on student recall of the messages, adjustment to college, and learning. A quasi-experimental design was used to examine differences between students (n = 302) assigned to one of three conditions: control group, message-only group, and message and experience group. The message and experience group learned about the university’s core value messages as part of their course curriculum, engaged in an out-of-class experience focused on these value messages, and completed a group problem-solving project related to these messages. The message only group learned about the university’s value messages and completed the same group problem-solving project, but did not engage in the out-of-class experience. The control group did not learn about the university’s messaging and completed the group problem-solving project related to a campus-based problem of their choice. Results reveal significant differences in student recall of the messages and student learning. No differences emerged in student adjustment to college based on experimental groupings. The results suggest communicating these messages solely in the basic communication course may not be a sufficient condition for facilitating student adjustment to the university’s culture

Substructure in clusters containing wide-angle tailed radio galaxies. I. New redshifts

We present new redshifts and positions for 635 galaxies in nine rich clusters containing Wide-Angle Tailed (WAT) radio galaxies. Combined with existing data, we now have a sample of 18 WAT-containing clusters with more than 10 redshifts. This sample contains a substantial portion of the WAT clusters in the VLA 20 cm survey of Abell clusters, including 75% of WAT clusters in the complete survey (z0.09. It is a representative sample which should not contain biases other than selection by radio morphology. We graphically present the new data using histograms and sky maps. A semi-automated procedure is used to search for emission lines in the spectra in order to add and verify galaxy redshifts. We find that the average apparent fraction of emission line galaxies is about 9% in both the clusters and the field. We investigate the magnitude completeness of our redshift surveys with CCD data for a test case, Abell 690. This case indicates that our galaxy target lists are deeper than the detection limit of a typical MX exposure, and they are 82% complete down to R=19.0. The importance of the uniformity of the placement of fibers on targets is posited, and we evaluate this in our datasets. We find some cases of non-uniformities which may influence dynamical analyses. A second paper will use this database to look for correlations between the WAT radio morphology and the cluster's dynamical state.Comment: 15 pages, 5 figures, 7 tables. To appear in the Astronomical Journa

Merging virtual and real execution level control software for the Phoenix autonomous underwater vehicle

The Naval Postgraduate School (NPS) is developing an AUV, Phoenix. The Phoenix has the capability of precise navigation, however too much time is needed to validate a new section of code. NPS is also developing a virtual AUV, which has the capability of being networked, having flexible missions, and having a quick feedback of results when validating new portions of code. The virtual AUV has a drawback of never being tested for real world precision. This thesis discusses the steps taken to combine these two sets of control code to obtain the maximum functionality that will drive either the virtual or actual AUV and produce a faster feedback response to newly developed code. As a result of this effort, the newly developed control code has successfully driven both the actual and virtual AUVs and provides a means for readily validating new code. Also this new control code has given the AUV research group the ability to perform distributed software development, test all AUV hardware from either the onboard or offboard computers, conduct flexible missions, and test missions in the virtual world prior to conducting them with the AUV.http://www.archive.org/details/mergingvirtualre00burnLieutenant, United States NavyApproved for public release; distribution is unlimited

Factors Associated with Employment among Latinos Living with HIV/AIDS

This investigation explored the utility of various demographic, health-related, and psychological variables in predicting employment among Latinos living with HIV/AIDS. Results of an analysis of variance indicated that employed participants were younger, evinced significantly greater CD4 counts, physical and mental health functioning, and internal locus of control beliefs than those who were unable to work due to disabilities. A backward binary logistic regression demonstrated that age, CD4 count, internal locus of control, and mental health functioning contributed to the explanatory power of the final model. This model correctly classified group membership 72% of the time, 78% of participants who were unable to work due to disabilities, and 65% of employed participants. The authors propose a variety of intervention strategies and directions for future rehabilitation research among Latinos living with HIV/AIDS

Thriving Instead of Surviving: The Role of the Reasoned Action Model in Assessing the Basic Course

The current study investigates the use of the reasoned action model (Fishbein & Ajzen, 2010) as an assessment tool for the basic communication course. Specifically, this study examines how attitude towards behaviors, subjective norms, and perceived behavioral control influence students’ behavioral intentions to use communication behaviors taught in the basic course outside of class. In addition to the stated variables in the reasoned action model, this study also examines how knowledge gain influences behavioral intention. Data was collected from 2,228 students enrolled in a basic communication course at a large southwestern university, and a random sample of 666 students was included in the analyses for the current study. Attitudes toward the behaviors, perceived behavioral control, and knowledge gain all positively influenced students’ behavioral intention to enact behaviors learned in the basic course, while subjective norms had a negative effect. The theoretical and practical implications discussed provide basic course directors with innovative ways to use the reasoned action model to assess the utility of the communication behaviors taught in basic courses

The Santa Fe Light Cone Simulation Project: I. Confusion and the WHIM in Upcoming Sunyaev-Zel'dovich Effect Surveys

We present the first results from a new generation of simulated large sky coverage (~100 square degrees) Sunyaev-Zeldovich effect (SZE) cluster surveys using the cosmological adaptive mesh refinement N-body/hydro code Enzo. We have simulated a very large (512^3h^{-3}Mpc^3) volume with unprecedented dynamic range. We have generated simulated light cones to match the resolution and sensitivity of current and future SZE instruments. Unlike many previous studies of this type, our simulation includes unbound gas, where an appreciable fraction of the baryons in the universe reside. We have found that cluster line-of-sight overlap may be a significant issue in upcoming single-dish SZE surveys. Smaller beam surveys (~1 arcmin) have more than one massive cluster within a beam diameter 5-10% of the time, and a larger beam experiment like Planck has multiple clusters per beam 60% of the time. We explore the contribution of unresolved halos and unbound gas to the SZE signature at the maximum decrement. We find that there is a contribution from gas outside clusters of ~16% per object on average for upcoming surveys. This adds both bias and scatter to the deduced value of the integrated SZE, adding difficulty in accurately calibrating a cluster Y-M relationship. Finally, we find that in images where objects with M > 5x10^{13} M_{\odot} have had their SZE signatures removed, roughly a third of the total SZE flux still remains. This gas exists at least partially in the Warm Hot Intergalactic Medium (WHIM), and will possibly be detectable with the upcoming generation of SZE surveys.Comment: 14 pages, 13 figures, version accepted to ApJ. Major revisions mad