1,294 research outputs found
Anti-Kaon Induced Reactions on the Nucleon
Using a previously established effective Lagrangian model we describe
anti-kaon induced reactions on the nucleon. The dominantly contributing
channels in the cm-energy region from threshold up to 1.72 GeV are included (K
N, \pi \Sigma, \pi \Lambda). We solve the Bethe-Salpeter equation in an unitary
-matrix approximation.Comment: 21 pages, 13 figures, minor typos corrected, accepted for publication
in Phys. Rev.
Revealing the X-ray Variability of AGN with Principal Component Analysis
We analyse a sample of 26 active galactic nuclei with deep XMM-Newton
observations, using principal component analysis (PCA) to find model
independent spectra of the different variable components. In total, we identify
at least 12 qualitatively different patterns of spectral variability, involving
several different mechanisms, including five sources which show evidence of
variable relativistic reflection (MCG-6-30-15, NGC 4051, 1H 0707-495, NGC 3516
and Mrk 766) and three which show evidence of varying partial covering neutral
absorption (NGC 4395, NGC 1365, and NGC 4151). In over half of the sources
studied, the variability is dominated by changes in a power law continuum, both
in terms of changes in flux and power law index, which could be produced by
propagating fluctuations within the corona. Simulations are used to find unique
predictions for different physical models, and we then attempt to qualitatively
match the results from the simulations to the behaviour observed in the real
data. We are able to explain a large proportion of the variability in these
sources using simple models of spectral variability, but more complex models
may be needed for the remainder. We have begun the process of building up a
library of different principal components, so that spectral variability in AGN
can quickly be matched to physical processes. We show that PCA can be an
extremely powerful tool for distinguishing different patterns of variability in
AGN, and that it can be used effectively on the large amounts of high-quality
archival data available from the current generation of X-ray telescopes.Comment: 25 pages, 27 figures, accepted to MNRAS. Analysis code available on
request to lead author. Edit: Rogue table remove
Simulation study of pressure and temperature dependence of the negative thermal expansion in Zn(CN)(2)
12 pages, 16 figures12 pages, 16 figures12 pages, 16 figures12 pages, 16 figure
Must naive realists be relationalists?
Relationalism maintains that perceptual experience involves, as part of its nature, a distinctive kind of conscious perceptual relation between a subject of experience and an object of experience. Together with the claim that perceptual experience is presentational, relationalism is widely believed to be a core aspect of the naive realist outlook on perception. This is a mistake. I argue that naive realism about perception can be upheld without a commitment to relationalism
Strategies for Managing Soil Fertility and Health in Organic Orchards - A Fact Sheet
This fact sheet is a report of research to provide fruit growers with locally adapted advice and solutions for managing soil fertility in certified organic stone-fruits.It includes information of transitioning to organic management; building soil organic matter and providing appropriate nutrients, including phosphorus, potassium, seconary nutrients and trace elements; soil testing; cover crops; mulches; and possible organic management systems
A large Hilbert space QRPA and RQRPA calculation of neutrinoless double beta decay
A large Hilbert space is used for the calculation of the nuclear matrix
elements governing the light neutrino mass mediated mode of neutrinoless double
beta decay of Ge76, Mo100, Cd116, Te128 and Xe136 within the proton-neutron
quasiparticle random phase approximation (pn-QRPA) and the renormalized QRPA
with proton-neutron pairing (full-RQRPA) methods. We have found that the
nuclear matrix elements obtained with the standard pn-QRPA for several nuclear
transitions are extremely sensitive to the renormalization of the
particle-particle component of the residual interaction of the nuclear
hamiltonian. Therefore the standard pn-QRPA does not guarantee the necessary
accuracy to allow us to extract a reliable limit on the effective neutrino
mass. This behaviour, already known from the calculation of the two-neutrino
double beta decay matrix elements, manifests itself in the neutrinoless
double-beta decay but only if a large model space is used. The full-RQRPA,
which takes into account proton-neutron pairing and considers the Pauli
principle in an approximate way, offers a stable solution in the physically
acceptable region of the particle-particle strength. In this way more accurate
values on the effective neutrino mass have been deduced from the experimental
lower limits of the half-lifes of neutrinoless double beta decay.Comment: 19 pages, RevTex, 1 Postscript figur
Political brand image: an investigation into the operationalisation of the external orientation of David Cameron’s Conservative brand
This paper seeks to address the limited understanding of how to operationalise the external brand image of a political brand. More specifically, this research critically assesses the transfer potential of the six variables of brand image by Bosch, Venter, Han and Boshoff to deconstruct the UK Conservative Party brand from the perspective of young people aged 18–24 years during the 2010 UK General Election campaign. This research demonstrates the applicability of the six variables otherwise known as the ‘brand image framework’ to the political environment. However, the application of the brand image framework in its original conceptualisation proved problematic. Many of the brand image variables were clarified, rearticulated and simplified to address the political context. This refined conceptualisation provided an in-depth understanding of how to investigate the political brand image of David Cameron’s Conservative Party. This study addresses the paucity of research that operationalises external brand image and provides practitioners and academics within and beyond the context of political branding a mechanism to understand the external orientation of brands. This research may also be used by political and non-political brands as a basis to explore external brand image and compare its consistency with internal brand identity
Enhancement of electroporation facilitated immunogene therapy via T-reg depletion
Regulatory T cells (T-regs) can negatively impact tumor antigen-specific immune responses after infiltration into tumor tissue. However, depletion of T-regs can facilitate enhanced anti-tumor responses, thus augmenting the potential for immunotherapies. Here we focus on treating a highly aggressive form of cancer using a murine melanoma model with a poor prognosis. We utilize a combination of T-reg depletion and immunotherapy plasmid DNA delivered into the B16F10 melanoma tumor model via electroporation. Plasmids encoding murine granulocyte macrophage colony-stimulating factor and human B71 were transfected with electroporation into the tumor and transient elimination of T-regs was achieved with CD25-depleting antibodies (PC61). The combinational treatment effectively depleted T-regs compared to the untreated tumor and significantly reduced lung metastases. The combination treatment was not effective in increasing the survival, but only effective in suppression of metastases. These results indicate the potential for combining T-reg depletion with immunotherapy-based gene electrotransfer to decrease systemic metastasis and potentially enhance survival
Ejection-accretion connection in NLS1 AGN 1H 1934-063
Accretion and ejection of matter in active galactic nuclei (AGNs) are tightly connected phenomena and represent fundamental mechanisms regulating the growth of the central supermassive black hole and the evolution of the host galaxy. However, the exact physical processes involved are not yet fully understood. We present a high-resolution spectral analysis of a simultaneous XMM-Newton and NuSTAR observation of the narrow line Seyfert 1 (NLS1) AGN 1H 1934-063, during which the X-ray flux dropped by a factor of ∼6 and subsequently recovered within 140 kiloseconds. By means of the time-resolved and flux-resolved X-ray spectroscopy, we discover a potentially variable warm absorber and a relatively stable ultra-fast outflow (UFO, vUFO∼ -0.075 c) with a mild ionization state (log (ξ /erg, cm s-1) ∼ 1.6). The detected emission lines (especially a strong and broad feature around 1 keV) are of unknown origin and cannot be explained with emission from plasmas in photo- or collisional-ionization equilibrium. Such emission lines could be well described by a strongly blueshifted (z ∼-0.3) secondary reflection off the base of the equatorial outflows, which may reveal the link between the reprocessing of the inner accretion flow photons and the ejection. However, this scenario although being very promising is only tentative and will be tested with future observations
NuSTAR reveals the hidden nature of SS433
SS433 is the only Galactic binary system known to accrete at highly
super-critical rates, analogous to tidal disruption events, and needed to
explain the mass of some high redshift quasars. Probing the inner regions of
SS433 in the X-rays is crucial to understanding this system, and super-critical
accretion in general, but has not yet been possible due to obscuration. NuSTAR
observed SS433 in the hard X-ray band across multiple phases of its
super-orbital precession period. Spectral-timing tools have allowed us to
confirm that the hard X-ray emission from the inner regions is scattered
towards us by the walls of the wind-cone. By comparing to numerical models, we
determine an intrinsic X-ray luminosity of >= 3x10^37 erg/s and that, if viewed
face on, the apparent luminosity would be > 1x10^39 erg/s, confirming its
long-suspected nature as an ultraluminous X-ray source (ULX). A lag due to
absorption by Fe XXV/XXVI in outflowing material travelling at least 0.14-0.29c
matches absorption lines seen in ULXs and - in future - will allow us to map a
super-critical outflow for the first time.Comment: 24 pages, 8 figures, submitted for publicatio
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