Chandra Imaging and Spectroscopy of the Eastern XA Region of the Cygnus Loop Supernova Remnant

The XA region of the Cygnus Loop is a bright knot of X-ray emission on the eastern edge of the supernova remnant resulting from the interaction of the supernova blast wave with density enhancements at the edge of a precursor formed cavity. To study the nature and origin of the X-ray emission we use high spatial resolution images from Chandra. Our goal is to probe the density of various spectral extraction regions to form a picture of the cavity wall and characterize the interaction between this supernova and the local interstellar medium. We find that a series of regions along the edge of the X-ray emission appears to trace out the location of the cavity wall. The best fit plasma models result in two temperature component equilibrium models for each region. The low temperature components have densities that are an order of magnitude higher than the high temperature components. The high density plasma may exist in the cavity wall where it equilibrates rapidly and cools efficiently. The low density plasma is interior to the enhancement and heated further by a reverse shock from the wall. Calculations of shock velocities and timescales since shock heating are consistent with this interpretation. Furthermore, we find a bright knot of emission indicative of a discrete interaction of the blast wave with a high density cloud in the cavity wall with a size scale ~0.1 pc. Aside from this, other extractions made interior to the X-ray edge are confused by line of sight projection of various components. Some of these regions show evidence of detecting the cavity wall but their location makes the interpretation difficult. In general, the softer plasmas are well fit at temperatures kT~0.11 keV, with harder plasmas at temperatures of kT~0.27 keV. All regions display consistent metal depletions most notably in N, O, and Ne at an average of 0.54, 0.55, and 0.36 times solar

Where is My Attention?

Attention is the key to all learning. Indeed, it is what will save our lives on a daily basis. In all my Communication courses, it is one of the first things I put forward as a question that students may ask of themselves as a check on their “internal considering.” Philosopher/practitioner George Gurdjieff (1866-1949) called the constant rumble in our minds of random condemnations and re-imaginings of past events as “internal considering.” He felt it was detrimental to ourselves and our relationships with others; it is, I maintain, a constant “self considering” that takes us away from the present and “being here now.” So recognizing that we are often not paying attention to what is happening in the space we are in now, with the people we are with now, is the first step in correcting this distracting state of affairs

Time resolved observation of resonant and non-resonant contributions to the nonlinear susceptibility χ(3)

The resonant and nonresonant part of χ(3) are distinguished by their different time behavior. The medium is coherently excited by two picosecond light pulses of defined frequency difference and the state of the system is monitored by a third properly delayed probe pulse. Results are presented on neat liquids of carbontetrachloride and cyclohexane and on the mixture of CCl4: C6H12

The Strength of Occupation Indicators as a Proxy for Skill

Labor economists have long used occupation indicators as a proxy for unobserved skills that a worker possesses. In this paper, we consider whether inter-occupational wage differentials that are unexplained by measured human capital are indeed due to differences in often-unmeasured skill. Using the National Compensation Survey, a large, nationally- representative dataset on jobs and ten different components of requisite skill, we compare the effects on residual wage variation of including occupation indicators and including additional skills measures. We find that although skills do vary across 3-digit occupations, occupation indicators decrease wage residuals by far more than can be explained by skill differentials. This indicates that “controlling for occupation” does not equate to controlling for skill alone, but also for some other factors to a great extent. Additionally, we find that there is considerable within occupation variation in skills, and that the amount of variation is not constant across skill levels. As a result, including occupation indicators in a wage model introduces heteroskedasticity that must be accounted for. We suggest that greater caution be applied when using and interpreting occupation indicators as controls in wage regressions.human capital measurement; job skills; occupation indicator variables

Spectral imaging in preclinical research and clinical pathology.

Spectral imaging methods are attracting increased interest from researchers and practitioners in basic science, pre-clinical and clinical arenas. A combination of better labeling reagents and better optics creates opportunities to detect and measure multiple parameters at the molecular and cellular level. These tools can provide valuable insights into the basic mechanisms of life, and yield diagnostic and prognostic information for clinical applications. There are many multispectral technologies available, each with its own advantages and limitations. This chapter will present an overview of the rationale for spectral imaging, and discuss the hardware, software and sample labeling strategies that can optimize its usefulness in clinical settings

The Leah and Samuel Levenson Papers

Samuel Levenson was a Worcester native who received his A.B. from Clark University in 1930 and his A.M. in 1936. He was a journalist and both he and his wife, Leah, were authors of biographies. Samuel died in 1977 and Leah in 2000 and Leah left their papers and library without restriction to Clark University in her will. Appropriate books were incorporated into the Goddard Library circulating collection. The books written by the Levensons were primarily biographies of Irish men and women. The papers include transcriptions and tapes of interviews made in the course of the Levensons’ researches, photographs of the biographees, authorizations and permissions forms, contracts, and journals written by Granville Hicks. Leah was working on a biography of Abbie Hoffman at the time of her death and the papers include notes, tapes and a rough draft. There are also many letters written by Samuel to Leah while he was in the army during World War II, some of which are transcribed

The origin of the X-ray emitting plasma in the eastern edge of the Cygnus Loop

The Cygnus Loop is interacting with a protrusion of the cavity wall in its eastern edge (the XA region), where the X-ray emission is very bright. The complexity of the environment and the non-linear physical processes of the shock-cloud interaction make the origin of the X-ray emission still not well understood. Our purpose is to understand the physical origin of the X-ray emission in the XA region, addressing, in particular, the role of thermal conduction in the interaction process. We analyzed two XMM-Newton data sets, performing image analysis and spatially resolved spectral analysis on a set of homogeneous regions. We applied a recently developed diagnostic tool to compare spectral analysis results with predictions of theoretical models, and to estimate the efficiency of thermal conduction on the X-ray emitting shocked plasma. We found that the inhomogeneous cavity wall contains both large clumps (the protrusion) and small isolated clumps with different densities. A large indentation bent over to the south is detected. The abundance of the surrounding ISM is ~0.2 times solar value. We confirmed the important role of thermal conduction in the evolution of X-ray emitting plasma during shock-cloud interaction.Comment: 7 pages, 5 figures, MNRAS in pres

Flow\u27r Of France Bloom Again

https://digitalcommons.library.umaine.edu/mmb-vp/5153/thumbnail.jp