62,081 research outputs found
A Far-Ultraviolet Spectroscopic Survey of Low-Redshift AGN
Using the Far Ultraviolet Spectroscopic Explorer (FUSE) we have obtained 87
spectra of 57 low-redshift (z<0.15) active galactic nuclei (AGN). This sample
comprises 53 Type 1 AGN and 4 Type 2. All the Type 1 objects show broad O VI
1034 emission; two of the Type 2s show narrow O VI emission. In addition to O
VI, we also identify emission lines due to C III 977, N III 991, S IV
1062,1072, and He II 1085 in many of the Type-1 AGN. Of the Type 1 objects, 30
show intrinsic absorption by the O VI 1032,1038 doublet. Most of these
intrinsic absorption systems show multiple components with intrinsic widths of
100 km/s spread over a blue-shifted velocity range of less than 1000 km/s.
Galaxies in our sample with existing X-ray or longer wavelength UV observations
also show C IV absorption and evidence of a soft X-ray warm absorber. In some
cases, a UV absorption component has physical properties similar to the X-ray
absorbing gas, but in others there is no clear physical correspondence between
the UV and X-ray absorbing components. Models in which a thermally driven wind
evaporates material from the obscuring torus naturally produce such
inhomogeneous flows.Comment: Contributed paper to appear in the proceedings of the Guillermo Haro
2003 Conference on Multiwavelength AGN Surveys; 3 pages, 1 figur
Regularizing the quark-level model
We show that the finite difference, , between quadratic and
logarithmic divergent integrals ,
as encountered in the linear model, is in fact regularization
independent.Comment: 9 pages, 2 figures, Latex, to appear in Mod. Phys. Lett.
Lepton flavour violation in future linear colliders in the long-lived stau NLSP scenario
We analyze the prospects of observing lepton flavour violation in future e-e-
and e+e- linear colliders in scenarios where the gravitino is the lightest
supersymmetric particle, and the stau is the next-to-lightest supersymmetric
particle. The signals consist of multilepton final states with two heavily
ionizing charged tracks produced by the long-lived staus. The Standard Model
backgrounds are very small and the supersymmetric backgrounds can be kept well
under control by the use of suitable kinematical cuts. We discuss in particular
the potential of the projected International Linear Collider to discover lepton
flavour violation in this class of scenarios, and we compare the estimated
sensitivity with the constraints stemming from the non-observation of rare
decays.Comment: 30 pages, 12 figures. Discussion extended to include the efficiency
of identifying long-lived staus, references added. To appear in JHE
On the detectability of the CMSSM light Higgs boson at the Tevatron
We examine the prospects of detecting the light Higgs h^0 of the Constrained
MSSM at the Tevatron. To this end we explore the CMSSM parameter space with
\mu>0, using a Markov Chain Monte Carlo technique, and apply all relevant
collider and cosmological constraints including their uncertainties, as well as
those of the Standard Model parameters. Taking 50 GeV < m_{1/2}, m_0 < 4 TeV,
|A_0| < 7 TeV and 2 < tan(beta) < 62 as flat priors and using the formalism of
Bayesian statistics we find that the 68% posterior probability region for the
h^0 mass lies between 115.4 GeV and 120.4 GeV. Otherwise, h^0 is very similar
to the Standard Model Higgs boson. Nevertheless, we point out some enhancements
in its couplings to bottom and tau pairs, ranging from a few per cent in most
of the CMSSM parameter space, up to several per cent in the favored region of
tan(beta)\sim 50 and the pseudoscalar Higgs mass of m_A\lsim 1 TeV. We also
find that the other Higgs bosons are typically heavier, although not
necessarily much heavier. For values of the h^0 mass within the 95% probability
range as determined by our analysis, a 95% CL exclusion limit can be set with
about 2/fb of integrated luminosity per experiment, or else with 4/fb (12/fb) a
3 sigma evidence (5 sigma discovery) will be guaranteed. We also emphasize that
the alternative statistical measure of the mean quality-of-fit favors a
somewhat lower Higgs mass range; this implies even more optimistic prospects
for the CMSSM light Higgs search than the more conservative Bayesian approach.
In conclusion, for the above CMSSM parameter ranges, especially m_0, either
some evidence will be found at the Tevatron for the light Higgs boson or, at a
high confidence level, the CMSSM will be ruled out.Comment: JHEP versio
The impact of diabetes-related complications on healthcare costs: results from the United Kingdom Prospective Diabetes Study (UKPDS Study No. 65)
<b>Aims</b> To develop a model for estimating the immediate and long-term healthcare costs associated with seven diabetes-related complications in patients with Type 2 diabetes participating in the UK Prospective Diabetes Study (UKPDS).
<b>Methods</b> The costs associated with some major complications were estimated using data on 5102 UKPDS patients (mean age 52.4 years at diagnosis). In-patient and out-patient costs were estimated using multiple regression analysis based on costs calculated from the length of admission multiplied by the average specialty cost and a survey of 3488 UKPDS patients’ healthcare usage conducted in 1996–1997.
<b>Results</b> Using the model, the estimate of the cost of first complications were as follows: amputation £8459 (95% confidence interval £5295, £13 200); non-fatal myocardial infarction £4070 (£3580, £4722); fatal myocardial infarction £1152 (£941, £1396); fatal stroke £3383 (£1935, £5431); non-fatal stroke £2367 (£1599, £3274); ischaemic heart disease £1959 (£1467, £2541); heart failure £2221 (£1690, £2896); cataract extraction £1553 (£1320, £1855); and blindness in one eye £872 (£526, £1299). The annual average in-patient cost of events in subsequent years ranged from £631 (£403, £896) for heart failure to £105 (£80, £142) for cataract extraction. Non-in-patient costs for macrovascular complications were £315 (£247, £394) and for microvascular complications were £273 (£215, £343) in the year of the event. In each subsequent year the costs were, respectively, £258 (£228, £297) and £204 (£181, £255).
<b>Conclusions</b> These results provide estimates of the immediate and long-term healthcare costs associated with seven diabetes-related complications
Non-universal gauge boson and the spin correlation of top quark pair production at colliders
In the off-diagonal basis, we discuss the contributions of the non-universal
gauge boson predicted by the topcolor-assisted technicolor () model
to the spin configurations and the spin correlation observable of the top quark
pair production via the process . Our numerical results
show that the production cross sections for the like-spin states, which vanish
in the standard model, can be significantly large as .
With reasonable values of the mass and the coupling parameter
,
exchange can generate large corrections to the spin correlation
observable.Comment: 16 pages, 5 figure
Radiative corrections to the semileptonic and hadronic Higgs-boson decays H -> W W/Z Z -> 4 fermions
The radiative corrections of the strong and electroweak interactions are
calculated for the Higgs-boson decays H -> WW/ZZ -> 4f with semileptonic or
hadronic four-fermion final states in next-to-leading order. This calculation
is improved by higher-order corrections originating from heavy-Higgs-boson
effects and photonic final-state radiation off charged leptons. The W- and
Z-boson resonances are treated within the complex-mass scheme, i.e. without any
resonance expansion or on-shell approximation. The calculation essentially
follows our previous study of purely leptonic final states. The electroweak
corrections are similar for all four-fermion final states; for integrated
quantities they amount to some per cent and increase with growing Higgs-boson
mass M_H, reaching 7-8% at M_H \sim 500 GeV. For distributions, the corrections
are somewhat larger and, in general, distort the shapes. Among the QCD
corrections, which include corrections to interference contributions of the
Born diagrams, only the corrections to the squared Born diagrams turn out to be
relevant. These contributions can be attributed to the gauge-boson decays, i.e.
they approximately amount to \alpha_s/\pi for semileptonic final states and
2\alpha_s/\pi for hadronic final states. The discussed corrections have been
implemented in the Monte Carlo event generator PROPHECY4F.Comment: 29 pages, LaTeX, 30 postscript figure
Observations of transients and pulsars with LOFAR international stations
The LOw FRequency ARray - LOFAR is a new radio telescope that is moving the
science of radio pulsars and transients into a new phase. Its design places
emphasis on digital hardware and flexible software instead of mechanical
solutions. LOFAR observes at radio frequencies between 10 and 240 MHz where
radio pulsars and many transients are expected to be brightest. Radio frequency
signals emitted from these objects allow us to study the intrinsic pulsar
emission and phenomena such as propagation effects through the interstellar
medium. The design of LOFAR allows independent use of its stations to conduct
observations of known bright objects, or wide field monitoring of transient
events. One such combined software/hardware solution is called the Advanced
Radio Transient Event Monitor and Identification System (ARTEMIS). It is a
backend for both targeted observations and real-time searches for millisecond
radio transients which uses Graphical Processing Unit (GPU) technology to
remove interstellar dispersion and detect millisecond radio bursts from
astronomical sources in real-time using a single LOFAR station.Comment: To appear in the proceedings of the Electromagnetic Radiation from
Pulsars and Magnetars conference, Zielona Gora, 2012. 4 pages, 1 figur
Hepatitis B and C co-Infection are independent predictors of progressive kidney disease in HIV-positive, antiretroviral-treated adults
Chronic kidney disease (CKD) is an important cause of morbidity and mortality in HIV-positive individuals. Hepatitis C (HCV) co-infection has been associated with increased risk of CKD, but prior studies lack information on potential mechanisms. We evaluated the association between HCV or hepatitis B (HBV) co-infection and progressive CKD among 3,441 antiretroviral-treated clinical trial participants. Progressive CKD was defined as the composite of end-stage renal disease, renal death, or significant glomerular filtration rate (eGFR) decline (25% decline to eGFR 800,000 IU/ml had increased odds (OR 3.07; 95% CI 1.60–5.90). Interleukin-6, hyaluronic acid, and the FIB-4 hepatic fibrosis index were higher among participants who developed progressive CKD, but were no longer associated with progressive CKD after adjustment. Future studies should validate the relationship between HCV viremia and CKD
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