4,207 research outputs found
Discovery of an X-ray Jet and Extended Jet Structure in the Quasar PKS 1055+201
This letter reports rich X-ray jet structures found in the Chandra
observation of PKS 1055+201. In addition to an X-ray jet coincident with the
radio jet we detect a region of extended X-ray emission surrounding the jet as
far from the core as the radio hotspot to the North, and a similar extended
X-ray region along the presumed path of the unseen counterjet to the Southern
radio lobe. Both X-ray regions show a similar curvature to the west, relative
to the quasar. We interpret this as the first example where we separately
detect the X-ray emission from a narrow jet and extended, residual jet plasma
over the entire length of a powerful FRII jet.Comment: Accepted for publication in Ap. J. Letters. 4 pages, 3 figure
Reinstating the 'no-lose' theorem for NMSSM Higgs discovery at the LHC
The simplest supersymmetric model that solves the mu problem and in which the
GUT-scale parameters need not be finely tuned in order to predict the correct
value of the Z boson mass at low scales is the Next-to-Minimal Supersymmetric
Standard Model (NMSSM). However, in order that fine tuning be absent, the
lightest CP-even Higgs boson h should have mass ~100 GeV and SM couplings to
gauge bosons and fermions. The only way that this can be consistent with LEP
limits is if h decays primarily via h->aa->4 tau or 4j but not 4b, where a is
the lighter of the two pseudo-scalar Higgses that are present in the NMSSM.
Interestingly, m_a 2 m_tau somewhat
preferred. Thus, h -> 4 tau becomes a key mode of interest. Meanwhile, all
other Higgs bosons of the NMSSM are typically quite heavy. Detection of any of
the NMSSM Higgs bosons at the LHC in this preferred scenario will be very
challenging using conventional channels. In this paper, we demonstrate that the
h -> aa -> 4 tau decay chain should be visible if the Higgs is produced in the
process pp -> p+h+p with the final state protons being measured using suitably
installed forward detectors. Moreover, we show that the mass of both the h and
the a can be determined on an event-by-event basis.Comment: 23 page
Proceedings of the workshop "Standard Model at the LHC" University College London 30 March - 1 April 2009
Proceedings from a 3-day discussion on Standard Model discoveries with the
first LHC dataComment: 9 contributions to the proceedings of the LHC Standard Model worksho
Trapped and marginally trapped surfaces in Weyl-distorted Schwarzschild solutions
To better understand the allowed range of black hole geometries, we study
Weyl-distorted Schwarzschild solutions. They always contain trapped surfaces, a
singularity and an isolated horizon and so should be understood to be
(geometric) black holes. However we show that for large distortions the
isolated horizon is neither a future outer trapping horizon (FOTH) nor even a
marginally trapped surface: slices of the horizon cannot be infinitesimally
deformed into (outer) trapped surfaces. We consider the implications of this
result for popular quasilocal definitions of black holes.Comment: The results are unchanged but this version supersedes that published
in CQG. The major change is a rewriting of Section 3.1 to improve clarity and
correct an error in the general expression for V(r,\theta). Several minor
errors are also fixed - most significantly an incorrect statement made in the
introduction about the extent of the outer prison in Vaidya. 17 pages, 2
figure
Intermittent prophylactic antibiotics for bronchiectasis
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To evaluate the safety and efficacy of intermittent prophylactic antibiotics in the treatment of adults and children with bronchiectasis
Axl-EGFR receptor tyrosine kinase hetero-interaction provides EGFR with access to pro-invasive signalling in cancer cells
© The Author(s) 2016. Acquired resistance to conventional and targeted therapies is becoming a major hindrance in cancer management. It is increasingly clear that cancer cells are able to evolve and rewire canonical signalling pathways to their advantage, thus evading cell death and promoting cell invasion. The Axl receptor tyrosine kinase (RTK) has been shown to modulate acquired resistance to EGFR-targeted therapies in both breast and lung cancers. Glioblastoma multiforme (GBM) is a highly infiltrative and invasive form of brain tumour with little response to therapy. Both Axl and EGFR have been identified as major players in gliomagenesis and invasiveness. However, the mechanisms underlying a potential signalling crosstalk between EGFR and Axl RTKs are unknown. The purpose of this study was to investigate this novel and unconventional interaction among RTKs of different families in human GBM cells. With the use of western blotting, in vitro kinase activity, co-immunoprecipitation and bimolecular fluorescence complementation assays, we show that EGF stimulates activation of Axl kinase and that there is a hetero-interaction between the two RTKs. Through small interfering RNA knockdown and quantitative PCR screening, we identified distinct gene expression patterns in GBM cells that were specifically regulated by signalling from EGFR-EGFR, Axl-Axl and EGFR-Axl RTK parings. These included genes that promote invasion, which were activated only via the EGFR-Axl axis (MMP9), while EGFR-EGFR distinctly regulated the cell cycle and Axl-Axl regulated invasion. Our findings provide critical insights into the role of EGFR-Axl hetero-dimerisation in cancer cells and reveal regulation of cell invasion via Axl as a novel function of EGFR signalling
Estimating the functional form for the density dependence from life history data
Two contrasting approaches to the analysis of population dynamics are currently popular: demographic approaches where the associations between demographic rates and statistics summarizing the population dynamics are identified; and time series approaches where the associations between population dynamics, population density, and environmental covariates are investigated. In this paper, we develop an approach to combine these methods and apply it to detailed data from Soay sheep (Ovis aries). We examine how density dependence and climate contribute to fluctuations in population size via age- and sex-specific demographic rates, and how fluctuations in demographic structure influence population dynamics. Density dependence contributes most, followed by climatic variation, age structure fluctuations and interactions between density and climate. We then simplify the density-dependent, stochastic, age-structured demographic model and derive a new phenomenological time series which captures the dynamics better than previously selected functions. The simple method we develop has potential to provide substantial insight into the relative contributions of population and individual-level processes to the dynamics of populations in stochastic environments
Spectral ageing analysis of the double-double radio galaxy J1453+3308
We present new radio observations at frequencies ranging from 240 to 4860 MHz
of the well-known, double-double radio galaxy (DDRG), J1453+3308, using both
the Giant Metrewave Radio Telescope (GMRT) and the Very Large Array (VLA).
These observations enable us to determine the spectra of the inner and outer
lobes over a large frequency range and demonstrate that while the spectrum of
the outer lobes exhibits significant curvature, that of the inner lobes appears
practically straight. The break frequency, and hence the inferred synchrotron
age of the outer structure, determined from 16arcsec strips transverse to
the source axis, increases with distance from the heads of the lobes. The
maximum spectral ages for the northern and southern lobes are 47 and 58
Myr respectively. Because of the difference in the lengths of the lobes these
ages imply a mean separation velocity of the heads of the lobes from the
emitting plasma of 0.036c for both the northern and southern lobes. The
synchrotron age of the inner double is about 2 Myr which implies an advance
velocity of 0.1c, but these values have large uncertainties because the
spectrum is practically straight.Comment: 10 pages, 10 figures, 5 tables, accepted for publication in MNRA
Central exclusive production of longlived gluinos at the LHC
We examine the possibility of producing gluino pairs at the LHC via the
exclusive reaction pp -> p+gluino+gluino+p in the case where the gluinos are
long lived. Such long lived gluinos are possible if the scalar super-partners
have large enough masses. We show that it may be possible to observe the
gluinos via their conversion to R-hadron jets and measure their mass to better
than 1% accuracy for masses below 350 GeV with 300/fb of data.Comment: 13 pages, 9 figures. Minor corrections to version
The politics of in/visibility: carving out queer space in Ul'yanovsk
<p>In spite of a growing interest within sexualities studies in the concept of queer space (Oswin 2008), existing literature focuses almost exclusively on its most visible and territorialised forms, such as the gay scene, thus privileging Western metropolitan areas as hubs of queer consumer culture (Binnie 2004). While the literature has emphasised the political significance of queer space as a site of resistance to hegemonic gender and sexual norms, it has again predominantly focused on overt claims to public space embodied in Pride events, neglecting other less open forms of resistance.</p><p>
This article contributes new insights to current debates about the construction and meaning of queer space by considering how city space is appropriated by an informal queer network in Ul’ianovsk. The group routinely occupied very public locations meeting and socialising on the street or in mainstream cafés in central Ul’ianovsk, although claims to these spaces as queer were mostly contingent, precarious or invisible to outsiders. The article considers how provincial location affects tactics used to carve out communal space, foregrounding the importance of local context and collective agency in shaping specific forms of resistance, and questioning ethnocentric assumptions about the empowering potential of visibility.</p>
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