A limit to the X-ray luminosity of nearby normal galaxies

Emission is studied at luminosities lower than those for which individual discrete sources can be studied. It is shown that normal galaxies do not appear to provide the numerous low luminosity X-ray sources which could make up the 2-60 keV diffuse background. Indeed, upper limits suggest luminosities comparable with, or a little less than, that of the galaxy. This is consistent with the fact that the average optical luminosity of the sample galaxies within approximately 20 Mpc is slightly lower than that of the galaxy. An upper limit of approximately 1% of the diffuse background from such sources is derived

Preface: Challenging the Politics of the Teacher Accountability Movement

Explains that this issue is intended as a resource for anyone concerned with re-framing and taking back the educational conversation, moving toward meaningful school reform that is based in a commitment to creating conditions under which teachers can develop the kinds of complex and sophisticated professional knowledges and practices that support authentic student learning

Introduction to Carol Rogers-Shaw’s “Disabled Lives and Pandemic Lives: Stories of Human Precarity”

The idea for Carol Rogers-Shaw’s essay began in April 2020, six weeks into the initial COVID lockdown, at her Zoom-based PhD dissertation defense. Carol’s dissertation brought together a narration of her life as a person with a disability and her work as a high school teacher of students with identified disabilities, conceptualized and reconceptualized through the lens of critical disability studies

Tort Law - Wrongful Birth and Wrongful Life Actions - Damages

The Pennsylvania Supreme Court has held that an infant cannot bring an action for wrongful life, but parents of the infant can maintain a cause of action for wrongful birth and recover damages for mental distress and physical inconvenience incident to the birth. Speck v. Finegold, 497 Pa. 77, 439 A.2d 110 (1981) (per curiam)

HEAO 1 measurements of the galactic ridge

The HEAO A2 experiment data was systematically searched for unresolved galactic disc emission. Although there were suggestions of non-uniformities in the emission, the data were consistent with a disc of half-thickness 241 + 22 pc and surface emissivity (2-10 keV) at galactic radius R(kpc) of 2.2 10 to the minus 7th power exp(-R/3.5) erg/sq cm to the (-2)power/s (R 7.8 kpc). giving a luminosity of approximately 4.4 10 to the 37th power erg S to the (-1) power. If the model is extrapolated to radii less than 7.8 kpc, the unresolved disc emission is approximately 1.4 10 to the 38th power erg S to the (-1) power (2-10 keV) i.e., a few percent of the luminosity of the galaxy in resolved sources. the disc emission has a spectrum which is significantly softer than that of the high galactic latitude diffuse X-ray background and it is most probably of discrete source origin

The X-ray spectrum of 3C 273

An X-ray spectral measurement of the quasar 3C 273 with the HEAO-A2 experiment in June/July 1978 is reported. The best power law fit to the photon flux over the range 2-60 keV gives a slope of 1.41 + or - 0.02. However, structure is observed, indicating a slope of 1.52 between 2 keV and 9 keV and a slight flattening between 9 keV and 30 keV. Observations with the same experiment in December 1977 and OSO-8 in June 1976 allows confirmation of 40% intensity variability on the time scale of months, although within limits provided by the poorer statistical quality of the additional data no spectral change is discerned. Absorption from the source is found to be low, with the 1978 data yielding a 90% confidence upper limit to the hydrogen column density of 4.5 x 10 to the 21st power atoms/sq cm

OSO-8 X-ray observations of AM Herculis

Hard X-ray observations of the binary system AM Her were coincident with soft X-ray and ground-based optical measurements. In the 2-60 KeV band, variability was detected with an eclipse during phases 0.5 to 0.7 with respect to the 0. d 12892 period optical minima, synchronous with the known soft X-ray eclipse. The 2-60 KeV uneclipsed flux was 9.5 x 10 to the minus 10th power erg sq cm/sec, of which 86% lies above 10 keV. Thus AM Her contains a hard source located near the similarly eclipsed soft X-ray source. The X-ray data are interpreted in terms of thermal bremsstrahlung from accretion onto a white dwarf

Introduction: Classroom Life in the Age of Accountability

For this Occasional Paper, we invited teachers to respond to the ways in which proliferation of standards and testing combined with their own loss of professional control is altering the landscape of American education....Our goal is to raise questions about whether and how educators are balancing the demands of high stakes testing, scripted curricula, and a focus on performance outcomes with the emotional complexity of classroom life. --The editor