490 research outputs found
The impact of the SZ effect on cm-wavelength (1-30 GHz) observation of galaxy cluster radio relics
(Abridged) Radio relics in galaxy clusters are believed to be associated with
powerful shock fronts that originate during cluster mergers, and are a testbed
for the acceleration of relativistic particles in the intracluster medium.
Recently, radio relic observations have pushed into the cm-wavelength domain
(1-30 GHz) where a break from the standard synchrotron power-law spectrum has
been found, most noticeably in the famous 'Sausage' relic. In this paper, we
point to an important effect that has been ignored or considered insignificant
while interpreting these new high-frequency radio data, namely the
contamination due to the Sunyaev-Zel'dovich (SZ) effect that changes the
observed synchrotron flux. Even though the radio relics reside in the cluster
outskirts, the shock-driven pressure boost increases the SZ signal locally by
roughly an order of magnitude. The resulting flux contamination for some
well-known relics are non-negligible already at 10 GHz, and at 30 GHz the
observed synchrotron fluxes can be diminished by a factor of several from their
true values. Interferometric observations are not immune to this contamination,
since the change in the SZ signal occurs roughly at the same length scale as
the synchrotron emission, although there the flux loss is less severe than
single-dish observations. We present a simple analytical approximation for the
synchrotron-to-SZ flux ratio, based on a theoretical radio relic model that
connects the non-thermal emission to the thermal gas properties, and show that
by measuring this ratio one can potentially estimate the relic magnetic fields
or the particle acceleration efficiency.Comment: Updated to the accepted version. Includes major text modifications
and a correction to the numerical coefficient in Eq. 15. Results and
conclusions are unchange
ALMA-SZ Detection of a Galaxy Cluster Merger Shock at Half the Age of the Universe
We present ALMA measurements of a merger shock using the thermal
Sunyaev-Zel'dovich (SZ) effect signal, at the location of a radio relic in the
famous El Gordo galaxy cluster at . Multi-wavelength analysis in
combination with the archival Chandra data and a high-resolution radio image
provides a consistent picture of the thermal and non-thermal signal variation
across the shock front and helps to put robust constraints on the shock Mach
number as well as the relic magnetic field. We employ a Bayesian analysis
technique for modeling the SZ and X-ray data self-consistently, illustrating
respective parameter degeneracies. Combined results indicate a shock with Mach
number , which in turn suggests a high value of
the magnetic field (of the order of G) to account for the observed
relic width at 2 GHz. At roughly half the current age of the universe, this is
the highest-redshift direct detection of a cluster shock to date, and one of
the first instances of an ALMA-SZ observation in a galaxy cluster. It shows the
tremendous potential for future ALMA-SZ observations to detect merger shocks
and other cluster substructures out to the highest redshifts.Comment: Matched to the ApJL published version (2016 September 22), minor
grammar and typo fixe
Comments on Marginal Deformations in Open String Field Theory
In this short letter we present a class of remarkably simple solutions to
Witten's open string field theory that describe marginal deformations of the
underlying boundary conformal field theory. The solutions we consider
correspond to dimension-one matter primary operators that have non-singular
operator products with themselves. We briefly discuss application to rolling
tachyons.Comment: 13 page
How to improve drug dosing for patients with renal impairment in primary care - a cluster-randomized controlled trial
Background: Patients with chronic kidney disease (CKD) are at increased risk for inappropriate or potentially harmful prescribing. The aim of this study was to examine whether a multifaceted intervention including the use of a software programme for the estimation of creatinine clearance and recommendation of individual dosage requirements may improve correct dosage adjustment of relevant medications for patients with CKD in primary care.
Methods: A cluster-randomized controlled trial was conducted between January and December 2007 in small primary care practices in Germany. Practices were randomly allocated to intervention or control groups. In each practice, we included patients with known CKD and elderly patients (>=70 years) suffering from hypertension. The practices in the intervention group received interactive training and were provided a software programme to assist with individual dose adjustment. The control group performed usual care. Data were collected at baseline and at 6 months. The outcome measures, analyzed across individual patients, included prescriptions exceeding recommended maximum daily doses, with the primary outcome being prescriptions exceeding recommended standard daily doses by 30% or more.
Results: Data from 44 general practitioners and 404 patients are included. The intervention was effective in reducing prescriptions exceeding the maximum daily dose per patients, with a trend in reducing prescriptions exceeding the standard daily dose by more than 30%.
Conclusions: A multifaceted intervention including the use of a software program effectively reduced inappropriately high doses of renally excreted medications in patients with CKD in the setting of small primary care practices
Heavy Neutral Gauge Bosons at the LHC in an Extended MSSM
Searching for heavy neutral gauge bosons Z', predicted in extensions of the
Standard Model based on a U(1)' gauge symmetry, is one of the challenging
objectives of the experiments carried out at the Large Hadron Collider. In this
paper, we study Z' phenomenology at hadron colliders according to several
U(1)'-based models and in the Sequential Standard Model. In particular,
possible Z' decays into supersymmetric particles are included, in addition to
the Standard Model modes so far investigated. We point out the impact of the
U(1)' group on the MSSM spectrum and, for a better understanding, we consider a
few benchmarks points in the parameter space. We account for the D-term
contribution, due to the breaking of U(1)', to slepton and squark masses and
investigate its effect on Z' decays into sfermions. Results on branching ratios
and cross sections are presented, as a function of the MSSM and U(1)'
parameters, which are varied within suitable ranges. We pay special attention
to final states with leptons and missing energy and make predictions on the
number of events with sparticle production in Z' decays, for a few values of
integrated luminosity and centre-of-mass energy of the LHC.Comment: 53 pages, 23 figures, 25 tables. One Feynman diagram fixed, results
and conclusions unchange
Boundary State from Ellwood Invariants
Boundary states are given by appropriate linear combinations of Ishibashi
states. Starting from any OSFT solution and assuming Ellwood conjecture we show
that every coefficient of such a linear combination is given by an Ellwood
invariant, computed in a slightly modified theory where it does not trivially
vanish by the on-shell condition. Unlike the previous construction of
Kiermaier, Okawa and Zwiebach, ours is linear in the string field, it is
manifestly gauge invariant and it is also suitable for solutions known only
numerically. The correct boundary state is readily reproduced in the case of
known analytic solutions and, as an example, we compute the energy momentum
tensor of the rolling tachyon from the generalized invariants of the
corresponding solution. We also compute the energy density profile of
Siegel-gauge multiple lump solutions and show that, as the level increases, it
correctly approaches a sum of delta functions. This provides a gauge invariant
way of computing the separations between the lower dimensional D-branes.Comment: v2: 63 pages, 14 figures. Major improvements in section 2. Version
published in JHE
Projektbericht: Provi-LK: Prozesskettenvirtualisierung in der Planung zur Entwicklung eines durchgängigen Lehr- und Lernkonzeptes
Ein Fach, in dem bisherige Lehrformen nur begrenzt geeignet sind den Stoff zu vermitteln, ist durch ihre computergestützte Vorgehensweise die Fertigungsplanung (NC-Planung). Gesamtziel des Projektes Provi-LK war es, eine für die charakteristischen Inhalte dieses Fachs geeignete Lehr- und Lernplattform zu entwickeln. Dabei sollte der Schwerpunkt vor allem auf der Nutzung digitaler Medien und selbstgesteuertem Lernen liegen. Als zusätzliches Lernangebot ist die Plattform zur Ergänzung für die klassischen Lehrformen an der Hochschule gedacht
Proton lifetime, Yukawa couplings and dynamical SUSY breaking in SU(5) GUT
We study the influence of messenger Yukawa couplings and top, bottom and
Yukawa couplings on the proton lifetime in SU(5) Supersymmetric GUT with
dynamical supersymmetry breaking mechanism due to Dine and Nelson.Comment: 7 pages latex file, 6 ps figures include
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