8,656 research outputs found
Generalizing a Unified Model of Dark Matter, Dark Energy, and Inflation with Non Canonical Kinetic Term
We study a unification model for dark energy, dark matter, and inflation with
a single scalar field with non canonical kinetic term. In this model the
kinetic term of the Lagrangian accounts for the dark matter and dark energy,
and at early epochs a quadratic potential accounts for slow roll inflation. The
present work is an extension to the work by Bose and Majumdar [1] with a more
general kinetic term that was proposed by Chimento in [2]. We demonstrate that
the model is viable at the background and linear perturbation levels.Comment: 8 pages, 2 figures. Minor changes to text and formulae, and added 3
references to match the published version in Phys. Rev.
Decomposition driven interface evolution for layers of binary mixtures: I. Model derivation and stratified base states
A dynamical model is proposed to describe the coupled decomposition and
profile evolution of a free surface film of a binary mixture. An example is a
thin film of a polymer blend on a solid substrate undergoing simultaneous phase
separation and dewetting. The model is based on model-H describing the coupled
transport of the mass of one component (convective Cahn-Hilliard equation) and
momentum (Navier-Stokes-Korteweg equations) supplemented by appropriate
boundary conditions at the solid substrate and the free surface.
General transport equations are derived using phenomenological
non-equilibrium thermodynamics for a general non-isothermal setting taking into
account Soret and Dufour effects and interfacial viscosity for the internal
diffuse interface between the two components. Focusing on an isothermal setting
the resulting model is compared to literature results and its base states
corresponding to homogeneous or vertically stratified flat layers are analysed.Comment: Submitted to Physics of Fluid
Detection and Mapping of Decoupled Stellar and Ionized Gas Structures in the Ultraluminous Infrared Galaxy IRAS 12112+0305
Integral field optical spectroscopy with the INTEGRAL fiber-fed system and
HST optical imaging are used to map the complex stellar and warm ionized gas
structure in the ultraluminous infrared galaxy IRAS 12112+0305. Images
reconstructed from wavelength-delimited extractions of the integral field
spectra reveal that the observed ionized gas distribution is decoupled from the
stellar main body of the galaxy, with the dominant continuum and emission-line
regions separated by projected distances of up to 7.5 kpc. The two optical
nuclei are detected as apparently faint emission-line regions, and their
optical properties are consistent with being dust-enshrouded weak-[OI] LINERs.
The brightest emission-line region is associated with a faint (m_{I}= 20.4),
giant HII region of 600 pc diameter, where a young (about 5 Myr) massive
cluster of about 2 10 dominates the ionization.
Internal reddening towards the line-emitting regions and the optical nuclei
ranges from 1 to 8 magnitudes, in the visual. Taken the reddening into aacount,
the overall star formation in IRAS 12112+0305 is dominated by starbursts
associated with the two nuclei and corresponding to a star formation rate of 80
yr.Comment: 2 figures, accepted to Ap.J. Letter
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A HEV-restricted sulfotransferase is expressed in rheumatoid arthritis synovium and is induced by lymphotoxin-alpha/beta and TNF-alpha in cultured endothelial cells.
BackgroundThe recruitment of lymphocytes to secondary lymphoid organs relies on interactions of circulating cells with high endothelial venules (HEV). HEV are exclusive to these organs under physiological conditions, but they can develop in chronically-inflamed tissues. The interaction of L-selectin on lymphocytes with sulfated glycoprotein ligands on HEV results in lymphocyte rolling, which represents the initial step in lymphocyte homing. HEV expression of GlcNAc6ST-2 (also known as HEC-GlcNAc6ST, GST-3, LSST or CHST4), an HEV-restricted sulfotransferase, is essential for the elaboration of L-selectin functional ligands as well as a critical epitope recognized by MECA-79 mAb.ResultsWe examined the expression of GlcNAc6ST-2 in relationship to the MECA-79 epitope in rheumatoid arthritis (RA) synovial vessels. Expression of GlcNAc6ST-2 was specific to RA synovial tissues as compared to osteoarthritis synovial tissues and localized to endothelial cells of HEV-like vessels and small flat-walled vessels. Double MECA-79 and GlcNAc6ST-2 staining showed colocalization of the MECA-79 epitope and GlcNAc6ST-2. We further found that both TNF-alpha and lymphotoxin-alphabeta induced GlcNAc6ST-2 mRNA and protein in cultured human umbilical vein endothelial cells.ConclusionThese observations demonstrate that GlcNAc6ST-2 is induced in RA vessels and provide potential cytokine pathways for its induction. GlcNAc6ST-2 is a novel marker of activated vessels within RA ectopic lymphoid aggregates. This enzyme represents a potential therapeutic target for RA
Graphene-Based Nanomaterials for Flexible and Wearable Supercapacitors
Along with the quick development of flexible and wearable electronic devices, there is an evergrowing demand for lightweight, flexible, and wearable power sources. Because of the high power density, excellent cycling stability and easy fabrication, flexible supercapacitors are widely studied for this purpose. Graphenebased nanomaterials are attractive electrode materials for flexible and wearable supercapacitors owing to their high surface area, good mechanical and electrical properties, and excellent electrochemical stability. The 2D structure and high aspect ratio of graphene nanosheets make them easy to assemble into films or fibers with good mechanical properties. In recent years, enormous progress has been made in developing flexible and wearable graphenebased supercapacitors. Here, the material and structure design strategies for developing filmshaped and emerging fibershaped flexible supercapacitors based on graphene nanomaterials are summarized
The Gribov horizon and the one-loop color-Coulomb potential
We recalculate the color-Coulomb potential to one-loop order, under the
assumption that the effect of the Gribov horizon is to make i) the transverse
gluon propagator less singular; and ii) the color-Coulomb potential more
singular, than their perturbative behavior in the low-momentum limit. As a
first guess, the effect of the Gribov horizon is mimicked by introducing a
transverse momentum-dependent gluon mass term, leading to a propagator of the
Gribov form, with the prescription that the mass parameter should be adjusted
to the unique value where the infrared behavior of the Coulomb potential is
enhanced. We find that this procedure leads to a Coulomb potential rising
asymptotically as a linear term modified by a logarithm.Comment: 15 pages, 2 figure
Optical Imaging of Very Luminous Infrared Galaxy Systems: Photometric Properties and Late Evolution
A sample of 19 low redshift (0.03z0.07) very luminous infrared galaxy
(VLIRG: L[8-1000 m] ) systems (30
galaxies) has been imaged in , , and . These objects cover a
luminosity range that is key to linking the most luminous infrared galaxies
with the population of galaxies at large. We have obtained photometry for all
of these VLIRG systems, the individual galaxies (when detached), and their
nuclei, and the relative behavior of these classes has been studied in optical
color-magnitude diagrams. The photometric properties of the sample are also
compared with previously studied samples of ULIRGs. The mean observed
photometric properties of VLIRG and ULIRG samples, considered as a whole, are
indistinguishable at optical wavelengths. This suggests that not only ULIRG,
but also the more numerous population of VLIRGs, have similar rest-frame
optical photometric properties as the submillimeter galaxies (SMG), reinforcing
the connection between low-{\it z} LIRGs -- high-{\it z} SMGs. When the nuclei
of the {\it young} and {\it old} interacting systems are considered separately,
some differences between the VLIRG and the ULIRG samples are found. In
particular, the old VLIRGs are less luminous and redder than old ULIRG systems.
If confirmed with larger samples, this behavior suggests that the late-stage
evolution is different for VLIRGs and ULIRGs. Specifically, as suggested from
spectroscopic data, the present photometric observations support the idea that
the activity during the late phases of VLIRG evolution is dominated by
starbursts, while a higher proportion of ULIRGs could evolve into a QSO type of
object.Comment: 27 pages, 5 figures (degraded to reduce space). Figures 1 and 2 are
multiple page figures (i.e. Fig 1a,b and Fig2a-g
Cylindrically symmetric spinning Brans-Dicke spacetimes with closed timelike curves
We present here three new solutions of Brans-Dicke theory for a stationary
geometry with cylindrical symmetry in the presence of matter in rigid rotation
with . All the solutions have eternal closed timelike curves
in some region of the spacetime, the size of which depends on .
Moreover, two of them do not go over a solution of general relativity in the
limit .Comment: revtex, 10 pages, 1 figure in p
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