827 research outputs found
Natural Warm Inflation
We derive the requirements that a generic axion-like field has to satisfy in
order to play the role of the inflaton field in the warm inflation scenario.
Compared to the parameter space in ordinary natural inflation models, we find
that the parameter space in our model is enlarged. In particular, we avoid the
problem of having an axion decay constant that relates to the Planck scale,
which is instead present in the ordinary natural inflation models; in fact, our
model can easily accommodate values of the axion decay constant that lie well
below the Planck scale.Comment: 19 pages, 7 figures; version accepted in JCA
Pregnancy Reprograms the Epigenome of Mammary Epithelial Cells and Blocks the Development of Premalignant Lesions
Pregnancy causes a series of cellular and molecular changes in mammary epithelial cells (MECs) of female adults. In addition, pregnancy can also modify the predisposition of rodent and human MECs to initiate oncogenesis. Here, we investigate how pregnancy reprograms enhancer chromatin in the mammary epithelium of mice and influences the transcriptional output of the oncogenic transcription factor cMYC. We find that pregnancy induces an expansion of the active cis-regulatory landscape of MECs, which influences the activation of pregnancy-related programs during re-exposure to pregnancy hormones in vivo and in vitro. Using inducible cMYC overexpression, we demonstrate that post-pregnancy MECs are resistant to the downstream molecular programs induced by cMYC, a response that blunts carcinoma initiation, but does not perturb the normal pregnancy-induced epigenomic landscape. cMYC overexpression drives post-pregnancy MECs into a senescence-like state, and perturbations of this state increase malignant phenotypic changes. Taken together, our findings provide further insight into the cell-autonomous signals in post-pregnancy MECs that underpin the regulation of gene expression, cellular activation, and resistance to malignant development
Quantized bulk fermions in the Randall-Sundrum brane model
The lowest order quantum corrections to the effective action arising from
quantized massive fermion fields in the Randall-Sundrum background spacetime
are computed. The boundary conditions and their relation with gauge invariance
are examined in detail. The possibility of Wilson loop symmetry breaking in
brane models is also analysed. The self-consistency requirements, previously
considered in the case of a quantized bulk scalar field, are extended to
include the contribution from massive fermions. It is shown that in this case
it is possible to stabilize the radius of the extra dimensions but it is not
possible to simultaneously solve the hierarchy problem, unless the brane
tensions are dramatically fine tuned, supporting previous claims.Comment: 25 pages, 1 figure, RevTe
Inhibition of somatosensory mechanotransduction by annexin A6
Mechanically activated, slowly adapting currents in sensory neurons have been linked to noxious mechanosensation. The conotoxin NMB-1 (noxious mechanosensation blocker-1) blocks such currents and inhibits mechanical pain. Using a biotinylated form of NMB-1 in mass spectrometry analysis, we identified 67 binding proteins in sensory neurons and a sensory neuron-derived cell line, of which the top candidate was annexin A6, a membrane-associated calcium-binding protein. Annexin A6-deficient mice showed increased sensitivity to mechanical stimuli. Sensory neurons from these mice showed increased activity of the cation channel Piezo2, which mediates a rapidly adapting mechano-gated current linked to proprioception and touch, and a decrease in mechanically activated, slowly adapting currents. Conversely, overexpression of annexin A6 in sensory neurons inhibited rapidly adapting currents that were partially mediated by Piezo2. Furthermore, overexpression of annexin A6 in sensory neurons attenuated mechanical pain in a mouse model of osteoarthritis, a disease in which mechanically evoked pain is particularly problematic. These data suggest that annexin A6 can be exploited to inhibit chronic mechanical pain
Convoluted models & high-Weissenberg predictions for micellar thixotropic fluids in contraction-expansion flows
This study is concerned with finite element/volume modelling of contraction-expansion axisymmetric pipe flows for thixotropic and non-thixotropic viscoelastic models. To obtain solutions at high Weissenberg numbers (Wi) under a general differential form , both thixotropic Bautista-Manero micellar and non-thixotropic EPTT f-functionals have been investigated. Here, three key modifications have been implemented: first, that of convoluting EPTT and micellar Bautista-Manero f-functionals, either in a multiplicative (Conv*) or additive (Conv+) form; second, by adopting f-functionals in absolute form (ABS-f-correction); and third, by imposing pure uniaxial-extension velocity-gradient components at the pure-stretch flow-centreline (VGR-correction). With this combination of strategies, highly non-linear solutions have been obtained to impressively high Wi [=O(5000+)].This capability permits analysis of industrial applications, typically displaying non-linear features such as thixotropy, yield stress and shear banding. The scope of applications covers enhanced oil- recovery, industrial processing of plastics and foods, as well as in biological and microfluidic flows. The impact of rheological properties across convoluted models (moderate-hardening, shear-thinning) has been observed through steady-state solutions and their excess pressure-drop (epd) production, stress, f-functional field structure, and vortex dynamics. Three phases of vortex-behaviour have been observed with rise in elasticity, along with upstream-downstream Moffatt vortices and plateauing epd-behaviour at high-Wi levels. Moreover, enhancement of positive-definiteness in stress has improved high-Wi solution attenuation
On the dissipative non-minimal braneworld inflation
We study the effects of the non-minimal coupling on the dissipative dynamics
of the warm inflation in a braneworld setup, where the inflaton field is
non-minimally coupled to induced gravity on the warped DGP brane. We study with
details the effects of the non-minimal coupling and dissipation on the
inflationary dynamics on the normal DGP branch of this scenario in the
high-dissipation and high-energy regime. We show that incorporation of the
non-minimal coupling in this setup decreases the number of e-folds relative to
the minimal case. We also compare our model parameters with recent
observational data.Comment: 32 pages, 6 figures. arXiv admin note: substantial text overlap with
arXiv:1001.044
Non-Minimal Warm Inflation and Perturbations on the Warped DGP Brane with Modified Induced Gravity
We construct a warm inflation model with inflaton field non-minimally coupled
to induced gravity on a warped DGP brane. We incorporate possible modification
of the induced gravity on the brane in the spirit of -gravity. We study
cosmological perturbations in this setup. In the case of two field inflation
such as warm inflation, usually entropy perturbations are generated. While it
is expected that in the case of one field inflation these perturbations to be
removed, we show that even in the absence of the radiation field, entropy
perturbations are generated in our setup due to non-minimal coupling and
modification of the induced gravity.Comment: 29 pages, 7 figures, Accepted by Gen. Rel Gravi
Metal enrichment processes
There are many processes that can transport gas from the galaxies to their
environment and enrich the environment in this way with metals. These metal
enrichment processes have a large influence on the evolution of both the
galaxies and their environment. Various processes can contribute to the gas
transfer: ram-pressure stripping, galactic winds, AGN outflows, galaxy-galaxy
interactions and others. We review their observational evidence, corresponding
simulations, their efficiencies, and their time scales as far as they are known
to date. It seems that all processes can contribute to the enrichment. There is
not a single process that always dominates the enrichment, because the
efficiencies of the processes vary strongly with galaxy and environmental
properties.Comment: 18 pages, 8 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 17; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
'Education, education, education' : legal, moral and clinical
This article brings together Professor Donald Nicolson's intellectual interest in professional legal ethics and his long-standing involvement with law clinics both as an advisor at the University of Cape Town and Director of the University of Bristol Law Clinic and the University of Strathclyde Law Clinic. In this article he looks at how legal education may help start this process of character development, arguing that the best means is through student involvement in voluntary law clinics. And here he builds upon his recent article which argues for voluntary, community service oriented law clinics over those which emphasise the education of students
A bright, high rotation-measure FRB that skewers the M33 halo
We report the detection of a bright fast radio burst, FRB\,191108, with
Apertif on the Westerbork Synthesis Radio Telescope (WSRT). The interferometer
allows us to localise the FRB to a narrow 5\arcsec\times7\arcmin ellipse by
employing both multibeam information within the Apertif phased-array feed (PAF)
beam pattern, and across different tied-array beams. The resulting sight line
passes close to Local Group galaxy M33, with an impact parameter of only
18\,kpc with respect to the core. It also traverses the much larger
circumgalactic medium of M31, the Andromeda Galaxy. We find that the shared
plasma of the Local Group galaxies could contribute 10\% of its
dispersion measure of 588\,pc\,cm. FRB\,191108 has a Faraday rotation
measure of +474\,\,rad\,m, which is too large to be explained by
either the Milky Way or the intergalactic medium. Based on the more moderate
RMs of other extragalactic sources that traverse the halo of M33, we conclude
that the dense magnetised plasma resides in the host galaxy. The FRB exhibits
frequency structure on two scales, one that is consistent with quenched
Galactic scintillation and broader spectral structure with
\,MHz. If the latter is due to scattering in the shared
M33/M31 CGM, our results constrain the Local Group plasma environment. We found
no accompanying persistent radio sources in the Apertif imaging survey data
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