144 research outputs found
Irish women in the diaspora: exclusions and inclusions
Irish women have a long history of emigration which provides parallels with the experiences of women now moving to settle in Ireland. In both cases, women migrants have been needed to fill the massive deficit of paid domestic labor in rapidly industrialising economies. Over the last two centuries, these destinations for Irish women have included the USA, Britain and Australia, as well as Canada, New Zealand, South Africa and Argentina. Some of the complexities in the positioning of migrant Irish women within the âdiaspora spacesâ they occupy are explored in this article. I identify ongoing disadvantage for certain groups of Irish-born women, drawing on evidence primarily from Britain, which has the largest contemporary diasporic Irish population. Comparisons are made with Irish women's experiences in the USA and Australia, using Census and survey data generated by and for the 2002 Task Force on Policy regarding Emigrants. The concept of diaspora explicitly includes those identifying themselves as Irish over several generations. I use qualitative findings from the Irish 2 Project, a recent study of the large second-generation Irish population in Britain, to examine narratives of women living in Manchester who grew up in âIrishâ households and are subsequently negotiating hybrid identities in adulthood. These offer insights into longitudinal dimensions of migrant experience and the continuing significance of ethnic difference
XMM-Newton and INTEGRAL observations of the very faint X-ray transient IGRJ17285-2922/XTEJ1728-295 during the 2010 outburst
We report the first broad-band (0.5-150 keV) simultaneous X-ray observations
of the very faint X-ray transient IGRJ17285-2922/XTEJ1728-295 performed with
XMM-Newton and INTEGRAL satellites during its last outburst, started on 2010,
August 28. XMM-Newton observed the source on 2010 September 9-10, for 22ks.
INTEGRAL observations were part of the publicly available Galactic Bulge
program, and overlapped with the times covered by XMM-Newton. The broad-band
spectroscopy resulted in a best-fit with an absorbed power law displaying a
photon index of 1.61+/-0.01, an absorbing column density of (5.10+/-0.05)E21
cm-2, and a flux of 2.4E-10 erg/cm2/s (1-100 keV), corrected for the
absorption. The data did not require either a spectral cut-off (E>50 keV) or an
additional soft component. The slopes of the XMM-Newton and INTEGRAL separate
spectra were compatible, within the uncertainties. The timing analysis does not
show evidence either for X-ray pulsations or for type I X-ray bursts. The broad
band X-ray spectrum as well as the power density spectrum are indicative of a
low hard state in a low mass X-ray binary, although nothing conclusive can be
said about the nature of the compact object (neutron star or black hole). The
results we are reporting here allow us to conclude that IGRJ17285-2922 is a low
mass X-ray binary, located at a distance greater than 4 kpc.Comment: Accepted for publication in MNRAS; 7 pages, 6 figure, 1 table.
Accepted 2011 April 5. Received 2011 April 5; in original form 2011 February
2
X-ray variation statistics and wind clumping in Vela X-1
We investigate the structure of the wind in the neutron star X-ray binary
system Vela X-1 by analyzing its flaring behavior. Vela X-1 shows constant
flaring, with some flares reaching fluxes of more than 3.0 Crab between 20-60
keV for several 100 seconds, while the average flux is around 250 mCrab. We
analyzed all archival INTEGRAL data, calculating the brightness distribution in
the 20-60 keV band, which, as we show, closely follows a log-normal
distribution. Orbital resolved analysis shows that the structure is strongly
variable, explainable by shocks and a fluctuating accretion wake. Analysis of
RXTE ASM data suggests a strong orbital change of N_H. Accreted clump masses
derived from the INTEGRAL data are on the order of 5 x 10^19 -10^21 g. We show
that the lightcurve can be described with a model of multiplicative random
numbers. In the course of the simulation we calculate the power spectral
density of the system in the 20-100 keV energy band and show that it follows a
red-noise power law. We suggest that a mixture of a clumpy wind, shocks, and
turbulence can explain the measured mass distribution. As the recently
discovered class of supergiant fast X-ray transients (SFXT) seems to show the
same parameters for the wind, the link between persistent HMXB like Vela X-1
and SFXT is further strengthened.Comment: 8 pages, 6 figures, accepted for publication in A&
The Birth of an Ultra-Luminous X-ray Source in M83
A previously undetected X-ray source (L_X<10**36 erg/s) in the strongly
star-forming galaxy M83 entered an ultraluminous state between August 2009 and
December 2010. It was first seen with Chandra on 23 December 2010 at L_X ~ 4
10**39 ergs/s, and has remained ultraluminous through our most recent
observations in December 2011, with typical flux variation of a factor of two.
The spectrum is well fitted by a combination of absorbed power-law and disk
black-body models. While the relative contributions of the models varies with
time, we have seen no evidence for a canonical state transition. The luminosity
and spectral properties are consistent with accretion powered by a black hole
with M_BH ~ 40-100 solar masses. In July 2011 we found a luminous, blue optical
counterpart which had not been seen in deep HST observations obtained in August
2009. These optical observations suggest that the donor star is a low-mass star
undergoing Roche-lobe overflow, and that the blue optical emission seen during
the outburst is coming from an irradiated accretion disk. This source shows
that ultraluminous X-ray sources (ULXs) with low-mass companions are an
important component of the ULX population in star-forming galaxies, and
provides further evidence that the blue optical counterparts of some ULXs need
not indicate a young, high-mass companion, but rather that they may indicate
X-ray reprocessing.Comment: 40 pages, 7 figures, accepted for publication in Ap
On the X-ray spectra of luminous, inhomogeneous accretion flows
We discuss the expected X-ray spectral and variability properties of black
hole accretion discs at high luminosity, under the hypothesis that radiation
pressure dominated discs are subject to violent clumping instabilities and, as
a result, have a highly inhomogeneous two-phase structure. After deriving the
full accretion disc solutions explicitly in terms of the parameters of the
model, we study their radiative properties both with a simple two-zones model,
treatable analytically, and with radiative transfer simulations which account
simultaneously for energy balance and Comptonisation in the hot phase, together
with reflection, reprocessing, ionization and thermal balance in the cold
phase. We show that, if not only the density, but also the heating rate within
these flows is inhomogeneous, then complex reflection-dominated spectra can be
obtained for a high enough covering fraction of the cold phase. In general,
large reflection components in the observed X-ray spectra should be associated
with strong soft excesses, resulting from the combined emission of ionized
atomic emission lines. The variability properties of such systems are such
that, even when contributing to a large fraction of the hard X-ray spectrum,
the reflection component is less variable than the power-law like emission
originating from the hot Comptonising phase, in agreement with what is observed
in many Narrow Line Seyfert 1 galaxies and bright Seyfert 1. Our model falls
within the family of those trying to explain the complex X-ray spectra of
bright AGN with ionized reflection, but presents an alternative, specific,
physically motivated, geometrical setup for the complex multi-phase structure
of the inner regions of near-Eddington accretion flows.Comment: 15 pages, 9 figures. MNRAS, in pres
Structural and functional characterization of endothelial microparticles released by cigarette smoke
Circulating endothelial microparticles (EMPs) are emerging as biomarkers of chronic obstructive pulmonary disease (COPD) in individuals exposed to cigarette smoke (CS), but their mechanism of release and function remain unknown. We assessed biochemical and functional characteristics of EMPs and circulating microparticles (cMPs) released by CS. CS exposure was sufficient to increase microparticle levels in plasma of humans and mice, and in supernatants of primary human lung microvascular endothelial cells. CS-released EMPs contained predominantly exosomes that were significantly enriched in let-7d, miR-191; miR-126; and miR125a, microRNAs that reciprocally decreased intracellular in CS-exposed endothelium. CS-released EMPs and cMPs were ceramide-rich and required the ceramide-synthesis enzyme acid sphingomyelinase (aSMase) for their release, an enzyme which was found to exhibit significantly higher activity in plasma of COPD patients or of CS-exposed mice. The ex vivo or in vivo engulfment of EMPs or cMPs by peripheral blood monocytes-derived macrophages was associated with significant inhibition of efferocytosis. Our results indicate that CS, via aSMase, releases circulating EMPs with distinct microRNA cargo and that EMPs affect the clearance of apoptotic cells by specialized macrophages. These targetable effects may be important in the pathogenesis of diseases linked to endothelial injury and inflammation in smokers
Titan airglow spectra from Cassini Ultraviolet Imaging Spectrograph (UVIS): EUV analysis
peer reviewedaudience: researcher, professional, studentWe present the first UV airglow observations of Titan's atmosphere by the Ultraviolet Imaging Spectrograph (UVIS) on Cassini. Using one spectral channel in the EUV from 561-1182 Ă
and one in the FUV from 1115-1913 Ă
, UVIS observed the disk on 13 December, 2004 at low solar activity. The EUV spectrum consists of three band systems of N[SUB]2[/SUB] (b [SUP]1[/SUP]â[SUB]u[/SUB], b' [SUP]1[/SUP]â[SUB]u[/SUB] [SUP]+[/SUP], c[SUB]4[/SUB]' [SUP]1[/SUP]â[SUB]u[/SUB] [SUP]+[/SUP] -> X [SUP]1[/SUP]â[SUB]g[/SUB] [SUP]+[/SUP]), while the FUV spectrum consists of one (a [SUP]1[/SUP]â[SUB]g[/SUB] -> X [SUP]1[/SUP]â[SUB]g[/SUB] [SUP]+[/SUP]). Both the EUV and FUV spectra contain many N I and N II multiplets that are produced primarily by photodissociative ionization. Spectral intensities of the N[SUB]2[/SUB] c[SUB]4[/SUB]' [SUP]1[/SUP]â[SUB]u[/SUB] [SUP]+[/SUP](v' = 0) -> X [SUP]1[/SUP]â[SUB]g[/SUB] [SUP]+[/SUP](v'' = 0-2) progression from 950-1010 Ă
are resolved for the first time. The UVIS observations reveal that the c[SUB]4[/SUB]' [SUP]1[/SUP]â[SUB]u[/SUB] [SUP]+[/SUP](0) -> X [SUP]1[/SUP]â[SUB]g[/SUB] [SUP]+[/SUP] (0) vibrational band near 958 Ă
is weak and undetectable, and that N I multiplets near 953.2 and 964.5 Ă
are present instead. Magnetospheric particle excitation may be weak or sporadic, since the nightside EUV spectrum on this orbit shows no observable nitrogen emission features and only H Ly-ÎČ
The ontogeny of color: developmental origins of divergent pigmentation in D rosophila americana and D . novamexicana
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92117/1/ede550.pd
MAXI J1659-152: The shortest orbital period black-hole transient in outburst
MAXI J1659-152 is a bright X-ray transient black-hole candidate binary system
discovered in September 2010. We report here on MAXI, RXTE, Swift, and
XMM-Newton observations during its 2010/2011 outburst. We find that during the
first one and a half week of the outburst the X-ray light curves display drops
in intensity at regular intervals, which we interpret as absorption dips. About
three weeks into the outbursts, again drops in intensity are seen. These dips
have, however, a spectral behaviour opposite to that of the absorption dips,
and are related to fast spectral state changes (hence referred to as transition
dips). The absorption dips recur with a period of 2.414+/-0.005 hrs, which we
interpret as the orbital period of the system. This implies that MAXI J1659-152
is the shortest period black-hole candidate binary known to date. The
inclination of the accretion disk with respect to the line of sight is
estimated to be 65-80 degrees. We propose the companion to the black-hole
candidate to be close to an M5 dwarf star, with a mass and radius of about
0.15-0.25 M_sun and 0.2-0.25 R_sun, respectively. We derive that the companion
had an initial mass of about 1.5 M_sun, which evolved to its current mass in
about 5-6 billion years. The system is rather compact (orbital separation of
larger than ~1.33 R_sun), and is located at a distance of 8.6+/-3.7 kpc, with a
height above the Galactic plane of 2.4+/-1.0 kpc. The characteristics of short
orbital period and high Galactic scale height are shared with two other
transient black-hole candidate X-ray binaries, i.e., XTE J1118+480 and Swift
J1735.5-0127. We suggest that all three are kicked out of the Galactic plane
into the halo, rather than being formed in a globular cluster.Comment: 20 pages, 14 figures, accepted for publication in A&
Whiteness and diasporic Irishness: nation, gender and class
Whiteness is often detached from the notion of diaspora in the recent flurry of interest in the phenomenon, yet it is a key feature of some of the largest and oldest displacements. This paper explores the specific contexts of white racial belonging and status over two centuries in two main destinations of the Irish diaspora, the USA and Britain. Its major contribution is a tracing of the untold story of âHow the Irish became white in Britainâ to parallel and contrast with the much more fully developed narrative in the USA. It argues that, contrary to popular belief, the racialisation of the Irish in England did not fade away at the end of the nineteenth century but became transmuted in new forms which have continued to place the âwhiteâ Irish outside the boundaries of the English nation. These have been strangely ignored by social scientists, who conflate Irishness and working-class identities in England without acknowledging the distinctive contribution of Irish backgrounds to constructions of class difference. Gender locates Irish women and men differently in relation to these class positions, for example allowing mothers to be blamed for the perpetuation of the underclass. Class and gender are also largely unrecognised dimensions of Irish ethnicity in the USA, where the presence of âpoor whiteâ neighbourhoods continues to challenge the iconic story of Irish upward mobility. Irishness thus remains central to the construction of mainstream âwhiteâ identities in both the USA and Britain into the twenty-first century
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