More examples of structure formation in the Lemaitre-Tolman model

In continuing our earlier research, we find the formulae needed to determine the arbitrary functions in the Lemaitre-Tolman model when the evolution proceeds from a given initial velocity distribution to a final state that is determined either by a density distribution or by a velocity distribution. In each case the initial and final distributions uniquely determine the L-T model that evolves between them, and the sign of the energy-function is determined by a simple inequality. We also show how the final density profile can be more accurately fitted to observational data than was done in our previous paper. We work out new numerical examples of the evolution: the creation of a galaxy cluster out of different velocity distributions, reflecting the current data on temperature anisotropies of CMB, the creation of the same out of different density distributions, and the creation of a void. The void in its present state is surrounded by a nonsingular wall of high density.Comment: LaTeX 2e with eps figures. 30 pages, 11 figures, 30 figure files. Revision matches published versio

Prospectus, February 13, 1980

STATE REPS, STUDENTS DISCUSS DRINKING AGE; Lazarro runs for State\u27s Atty.; Campaign puts Connally in Champaign; Certified by AORN; Volleython; Dental clinic; Campus Happenings; Guidelines for job applicants; Zippert to draw; Susan B. Anthony events; Parkland instructor\u27s drawings published; Philemon--Parkland College spring musical; Tired Bonoff raises spirits; Between the Tracks; Choir Concert changes skeptic\u27s view; Now there is frost upon the hill; Classifieds; Heart-throbbers; Trackmen impressive in Parkland get-together ; CIAC title hopes dashed with loss; Bench Warmer: King, Harris give Cobras consistency; Women win over Danville; Intramural teams head into third week of season; Intramural Basketball Standingshttps://spark.parkland.edu/prospectus_1980/1038/thumbnail.jp

Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets

The spins of ten stellar black holes have been measured using the continuum-fitting method. These black holes are located in two distinct classes of X-ray binary systems, one that is persistently X-ray bright and another that is transient. Both the persistent and transient black holes remain for long periods in a state where their spectra are dominated by a thermal accretion disk component. The spin of a black hole of known mass and distance can be measured by fitting this thermal continuum spectrum to the thin-disk model of Novikov and Thorne; the key fit parameter is the radius of the inner edge of the black hole's accretion disk. Strong observational and theoretical evidence links the inner-disk radius to the radius of the innermost stable circular orbit, which is trivially related to the dimensionless spin parameter a_* of the black hole (|a_*| < 1). The ten spins that have so far been measured by this continuum-fitting method range widely from a_* \approx 0 to a_* > 0.95. The robustness of the method is demonstrated by the dozens or hundreds of independent and consistent measurements of spin that have been obtained for several black holes, and through careful consideration of many sources of systematic error. Among the results discussed is a dichotomy between the transient and persistent black holes; the latter have higher spins and larger masses. Also discussed is recently discovered evidence in the transient sources for a correlation between the power of ballistic jets and black hole spin.Comment: 30 pages. Accepted for publication in Space Science Reviews. Also to appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher). Changes to Sections 5.2, 6.1 and 7.4. Section 7.4 responds to Russell et al. 2013 (MNRAS, 431, 405) who find no evidence for a correlation between the power of ballistic jets and black hole spi

Coronal Temperature Diagnostic Capability of the Hinode/X-Ray Telescope Based on Self-Consistent Calibration

The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray imager that observes the solar corona with unprecedentedly high angular resolution (consistent with its 1" pixel size). XRT has nine X-ray analysis filters with different temperature responses. One of the most significant scientific features of this telescope is its capability of diagnosing coronal temperatures from less than 1 MK to more than 10 MK, which has never been accomplished before. To make full use of this capability, accurate calibration of the coronal temperature response of XRT is indispensable and is presented in this article. The effect of on-orbit contamination is also taken into account in the calibration. On the basis of our calibration results, we review the coronal-temperature-diagnostic capability of XRT

Nurturing lifelong learning in communities through the National University of Lesotho: prospects and challenges

This paper analyses one aspect of a pan-African action research project called ITMUA (Implementing the Third Mission of Universities in Africa). This particular paper draws on the data from that project to explore the National University of Lesotho’s contribution to lifelong learning in its communities. It provides background information on the ITMUA initiative and analyses interview and focus group responses to two case studies in terms of their contribution to lifelong learning. It uses, as its analytical framework, a modified version of Mbigi’s African perspective on the four De Lors’ ‘pillars’, by adding a fifth pillar, courtesy of Torres. The paper argues that community engagement is a two-way process between universities and their wider constituencies with opportunities for mutual lifelong learning. But there are also challenges of understanding and process which must be addressed if the full range of these lifelong learning pillars is to be accommodated within African contexts. The paper provides an introduction to the history of community engagement in Africa as a university mission, followed by a brief discussion of lifelong learning within African perspectives. After describing the particular context of Lesotho, the concept of community service and community engagement in contemporary African contexts introduces the action research project and the case studies. The final part of the paper presents and discusses the research findings