KITD816V+ systemic mastocytosis associated with KITD816V+ acute erythroid leukaemia: first case report with molecular evidence for same progenitor cell derivation

Toll-like receptor (TLR)-9 recognizes CpG motifs in microbial DNA. TLR9 signalling stimulates innate antimicrobial immunity and modulates adaptive immune responses including autoimmunity against chromatin, e.g., in systemic lupus erythematosus (SLE). This review summarizes the available data for a role of TLR9 signalling in lupus and discusses the following questions that arise from these observations: 1) Is CpG-DNA/TLR9 interaction involved in infection-induced disease activity of lupus? 2) What are the risks of CpG motifs in vaccine adjuvants for lupus patients? 3) Is TLR9 signalling involved in the pathogenesis of lupus by recognizing self DNA

The politics of representation in the politics of anti-racism

In this short response to Gavan Titley’s new book Racism and Media, I engage with his discussion of the politics of the representation in relation to his important concept of debatability. I underline two key contributions made by Titley in the chapter “The Politics of Representation in Postracial Media Culture”: (1) the limitations of an anti-racist politics based on media representation alone and (2) how the politics of representation and the commentary and debate that it generates has become commodified and transformed into media content itself. I end the piece by suggesting some new routes for media-based anti-racist interventions, targeted at the level of political economy of the cultural industries

X-ray Nova XTE J1550-564: RXTE Spectral Observations

Excellent coverage of the 1998 outburst of the X-ray Nova XTE J1550-564 was provided by the Rossi X-ray Timing Explorer. XTE J1550-564 exhibited an intense (6.8 Crab) flare on 1998 September 19 (UT), making it the brightest new X-ray source observed with RXTE. We present a spectral analysis utilizing 60 Proportional Counter Array spectra from 2.5-20 keV spanning 71 days, and a nearly continuous All Sky Monitor light curve. The spectra were fit to a model including multicolor blackbody disk and power-law components. XTE J1550-564 is observed in the very high, high/soft, and intermediate canonical outburst states of Black Hole X-ray Novae.Comment: 14 pages including 1 table and 4 figures, Accepted to ApJ Letter

Neutron reflection from the liquid helium surface.

The reflection of neutrons from a helium surface has been observed for the first time. The 4He surface is smoother in the superfluid state at 1.54 K than in the case of the normal liquid at 2.3 K. In the superfluid state we also observe a surface layer ~200 Å thick which has a subtly different neutron scattering cross-section, which may be explained by an enhanced Bose-Einstein condensate fraction close to the helium surface. The application of neutron reflectometry described in this paper creates new and exciting opportunities for the surface and interfacial study of quantum fluids

A Chandra Observation of the Diffuse Emission Centered on the Low Mass X-ray Binary 4U 1755-33

We present an analysis of a Chandra observation of the field surrounding the low-mass X-ray binary 4U 1755-33, which has been in quiescence since 1996. In 2003, Angelini and White reported the appearance of a narrow 7 arcmin long jetlike feature centered on the position of 4U 1755-33 using the XMM-Newton telescope. Though the source and jet are not visibly apparent in our Chandra/ACIS-S image, there is a significant excess (4-6 sigma) of counts in a region that encloses the jet when compared to adjacent regions. We examined a knot of emission in the jet that was detected by XMM-Newton but not by Chandra and calculated that if the knot flux observed by XMM-Newton was concentrated in a point source, Chandra would have easily detected it; we therefore conclude that this knot of emission is diffuse. In summary, we suggest that the jetlike feature found previously in the XMM-Newton data is quite diffuse and likely a true jet, and is not due to a chance alignment of discrete point sources or point-like regions of emission associated with internal shocks.Comment: 5 pages, color figures, uses emulateapj.cls and apjfonts.sty, submitted to ApJ Letter

Multi-Temperature Blackbody Spectra of Thin Accretion Disks With and Without a Zero-Torque Inner Boundary Condition

The standard spectral model for analyzing the soft component of thermal emission from a thin accretion disk around a black hole is the multi-temperature blackbody (MTB) model. The widely used implementation of this model, which is known as ``diskbb,'' assumes nonzero torque at the inner edge of the accretion disk. This assumption is contrary to the classic and current literature on thin-disk accretion, which advocates the use of a zero-torque boundary condition. Consequently, we have written code for a zero-torque model, ``ezdiskbb,'' which we compare to the nonzero-torque model diskbb by fitting RXTE spectra of three well-known black hole binaries: 4U 1543-47, XTE J1550-564, and GRO J1655-40. The chief difference we find is that the zero-torque model gives a value for the inner disk radius that is about 2.2 times smaller than the value given by diskbb. This result has important implications, especially for the determination of black-hole angular momentum and mass accretion rate.Comment: 27 pages, 9 figures, submitted to Ap

Inclination Effects and Beaming in Black Hole X-ray Binaries

We investigate the dependence of observational properties of black hole X-ray binaries on the inclination angle i of their orbits. We find the following: (1) Transient black hole binaries show no trend in their quiescent X-ray luminosities as a function of i, suggesting that the radiation is not significantly beamed. This is consistent with emission from an accretion disk. If the X-rays are from a jet, then the Lorentz factor gamma of the jet is less than 1.24 at the 90% confidence level. (2) The X-ray binary 4U1543-47 with i of order 21 degrees has a surprisingly strong fluorescent iron line in the high soft state. Quantifying an earlier argument by Park et al. (2004), we conclude that if the continuum X-ray emission in this source is from a jet, then gamma < 1.04. (3) None of the known binaries has cos i 75 degrees. This fact, plus the lack of eclipses among the 20 black hole binaries in our sample, strongly suggests at the 99.5% confidence level that systems with large inclination angles are hidden from view. The obscuration could be the result of disk flaring, as suggested by Milgrom (1978) for neutron star X-ray binaries. (4) Transient black hole binaries with i ~ 70-75 degrees have significantly more complex X-ray light curves than systems with i < 65 degrees. This may be the result of variable obscuration and/or variable height above the disk of the radiating gas.Comment: 26 pages, to appear in The Astrophysical Journal, vol. 624, May 1, 200

X-ray Properties of Black-Hole Binaries

We review the properties and behavior X-ray binaries that contain an accreting black hole. The larger majority of such systems are X-ray transients, and many of them were observed in daily pointings with RXTE throughout the course of their outbursts. The complex evolution of these sources is described in terms of common behavior patterns illustrated with comprehensive overview diagrams for six selected systems. Central to this comparison are three X-ray states of accretion, which are reviewed and defined quantitatively. Each state yields phenomena that arise in strong gravitational fields. We sketch a scenario for the potential impact of black hole observations on physics and discuss a current frontier topic: the measurement of black hole spin.Comment: 39 pages, 12 figures, ARAA, vol. 44, in pres