Discovery of hard X-ray features around hotspots of Cygnus A

We present results of analysis of a Chandra observation of Cygnus A in which the X-ray hotspots at the ends of the jets are mapped in detail. A hardness map reveals previously unknown structure in the form of outer and inner hard arcs around the hotspots, with hardness significantly enhanced compared with the hotspot central regions. The outer hard arcs may constitute the first detection of the bow shock; the inner hard arcs may reveal where the jets impact on the hotspots. We argue that these features cannot result from electrons radiating by the synchrotron self-Compton process. Instead we consider two possible sources of the hard emission: the outer arcs may be due to thermal radiation of hot intracluster gas compressed at the bow shock. Alternatively, both outer and inner arcs may be due to synchrotron radiation of electrons accelerated in turbulent regions highly perturbed by shocks and shear flows. Comparison of measured hardness ratios with simulations of the hardness ratios resulting from these processes show that it is more diffcult to explain the observations with a thermal model. Although we cannot rule out a thermal model, we argue in favour of the non-thermal explanation. The hard regions in the secondary hotspots suggest that jet activity is still powering these hotspots.Comment: MNRAS in press; 5 pages, 3 figures (2 figures in colour in jpeg format should be printed separately

Development of a machine protection system for the Superconducting Beam Test Facility at Fermilab

Fermilab's Superconducting RF Beam Test Facility currently under construction will produce electron beams capable of damaging the acceleration structures and the beam line vacuum chambers in the event of an aberrant accelerator pulse. The accelerator is being designed with the capability to operate with up to 3000 bunches per macro-pulse, 5Hz repetition rate and 1.5 GeV beam energy. It will be able to sustain an average beam power of 72 KW at the bunch charge of 3.2 nC. Operation at full intensity will deposit enough energy in niobium material to approach the melting point of 2500 {\deg}C. In the early phase with only 3 cryomodules installed the facility will be capable of generating electron beam energies of 810 MeV and an average beam power that approaches 40 KW. In either case a robust Machine Protection System (MPS) is required to mitigate effects due to such large damage potentials. This paper will describe the MPS system being developed, the system requirements and the controls issues under consideration.Comment: 3 pp. 13th International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS 2011). 10-14 Oct 2011. Grenoble, Franc

Benchmark ages for the Gaia benchmark stars

In the era of large-scale surveys of stars in the Milky Way, stellar ages are crucial for studying the evolution of the Galaxy. But determining ages of field stars is notoriously difficult; therefore, we attempt to determine benchmark ages for the extensively studied Gaia benchmark stars which can be used for validation purposes. By searching the literature for age estimates from different methods and deriving new ages based on Bayesian isochrone fitting, we are able to put reliable limits on the ages of 16 out of the 33 benchmark stars. The giants with well-defined ages are all young, and an expansion of the sample to include older giants with asteroseismic ages would be beneficial. Some of the stars have surface parameters inconsistent with isochrones younger than 16 Gyr. Including $\alpha$-enhancement in the models when relevant resolves some of these cases, but others clearly highlight discrepancies between the models and observations. We test the impact of atomic diffusion on the age estimates by fitting to the actual surface metallicity of the models instead of the initial value and find that the effect is negligible except for a single turn-off star. Finally, we show that our ability to determine isochrone-based ages for large spectroscopic surveys largely mirrors our ability to determine ages for these benchmark stars, except for stars with $\log g \gtrsim 4.4$ dex since their location in the HR diagram is almost age insensitive. Hence, isochrone fitting does not constrain their ages given the typical uncertainties of spectroscopic stellar parameters.Comment: Accepted in MNRAS. 69 pages (18 for main text, 11 for appendix, and 40 for extra figures

Posture : a 4-H club activity

Cooperative Extension Work in Agriculture and Home Economics, University of Missouri, College of Agriculture and the United States Department of Agriculture cooperating."... Material in quotations has been taken from material by Miss Ella Gardner, Recreation Specialist, Extension Service, U. S. Department of Agriculture, Washington, D.C."--Page 3."June, 1939."Title from cover

Hips Unsocketed, Names Changed

This collection of poems represents my work from the past two years. I experiment with a variety of forms and measures, though most of these poems are in free verse. Two images serves as a cipher for understanding them as a whole: a peach tree and a red fox. Every year, I would wait in anticipation for the hard green buds to appear on the peach tree in my backyard, then, for them to change color, swelling with sweetness. By the time the ones that escaped the frost and insects were ripe enough to eat, I had forgotten about them and was surprised to see them on the kitchen table or catch a glimpse of red or orange in the leaves. Poetry has become my way of holding up my life’s fruits, my memories, to the sun to see how they have ripened. This metaphorical process of waiting and the renewed sense of discovery that comes with the long-awaited harvest define my experience of writing poetry. The second image, a red fox, has come to signify for me spiritual awareness and encounters with God in unexpected places. I have often seen red foxes in unlikely places. Poetry, for me, is a movement towards a deeper understanding of God. Poetry is searching for shalom in the midst of alienation, severed relationships, and ruptured selves. In summary, I seek a balanced and honest treatment of human heart-terrain, open to all emotions and experiences, with the ultimate aim of participating in God’s work of redemption and restoration

Oxygen Cost of Recreational Horse-Riding in Females

Version: as accepted for publication.BACKGROUND: The purpose of this study was to characterize the physiological demands of a riding session comprising different types of recreational horse riding in females. METHODS: Sixteen female recreational riders (aged 17 to 54 years) completed an incremental cycle ergometer exercise test to determine peak oxygen consumption (VO₂peak) and a 45-minute riding session based upon a British Horse Society Stage 2 riding lesson (including walking, trotting, cantering and work without stirrups). Oxygen consumption (VO₂), from which metabolic equivalent (MET) and energy expenditure values were derived, was measured throughout. RESULTS: The mean VO₂ requirement for trotting/cantering (18.4 ± 5.1 ml·kg⁻¹·min⁻¹; 52 ± 12% VO₂peak; 5.3 ± 1.1 METs) was similar to walking/trotting (17.4 ± 5.1 ml·kg⁻¹·min⁻¹; 48 ± 13% VO₂peak; 5.0 ± 1.5 METs) and significantly higher than for work without stirrups (14.2 ± 2.9 ml·kg⁻¹·min⁻¹; 41 ± 12% VO₂peak; 4.2 ± 0.8 METs) (P = .001). CONCLUSIONS: The oxygen cost of different activities typically performed in a recreational horse riding session meets the criteria for moderate intensity exercise (3-6 METs) in females, and trotting combined with cantering imposes the highest metabolic demand. Regular riding could contribute to the achievement of the public health recommendations for physical activity in this population

Discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X 1624-490 with XMM-Newton

We report the discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X 1624-490 during an XMM-Newton observation in 2001 February. The features are identified with the K alpha absorption lines of Fe xxv and Fe xxvi and have energies of 6.72 +/- 0.03 keV and 7.00 +/- 0.02 keV and equivalent widths (EWs) of -7.5 +1.7 -6.3 eV and -16.6 +1.9 -5.9 eV, respectively. The EWs show no obvious dependence on orbital phase, except during a dip, and correspond to a column of greater than 10^17.3 Fe atom /cm2. In addition, faint absorption features tentatively identified with Ni xxvii K alpha and Fe xxvi K beta may be present. A broad emission feature at 6.58 +0.07 -0.04 keV with an EW of 78 +19 -6 eV is also evident. This is probably the 6.4 keV feature reported by earlier missions since fitting a single Gaussian to the entire Fe-K region gives an energy of 6.39 +0.03 -0.04 keV. A deep absorption feature is present during the dip with an energy consistent with Fe xxv K alpha. This is the second dipping LMXRB source from which narrow Fe absorption features have been observed. Until recently the only X-ray binaries known to exhibit narrow X-ray absorption lines were two superluminal jet sources and it had been suggested that these features are related to the jet formation mechanism. It now appears likely that ionized absorption features may be common characteristics of accreting systems with accretion disks.Comment: 6 pages. To appear in A&

A comparison of consumer behavior of coin laundry users and beliefs about this behavior held by coin laundry owners

Thesis (M.B.A.)--Boston Universit