389 research outputs found
Static Charges in the Low-Energy Theory of the S-Duality Twist
We continue the study of the low-energy limit of N=4 super Yang-Mills theory
compactified on a circle with S-duality and R-symmetry twists that preserve N=6
supersymmetry in 2+1D. We introduce external static supersymmetric quark and
anti-quark sources into the theory and calculate the Witten Index of the
resulting Hilbert space of ground states on a torus. Using these results we
compute the action of simple Wilson loops on the Hilbert space of ground states
without sources. In some cases we find disagreement between our results for the
Wilson loop eigenvalues and previous conjectures about a connection with
Chern-Simons theory.Comment: 73 pages, two paragraphs added, one to the introduction and one to
the discussio
Directly Imaging Rocky Planets from the Ground
Over the past three decades instruments on the ground and in space have
discovered thousands of planets outside the solar system. These observations
have given rise to an astonishingly detailed picture of the demographics of
short-period planets, but are incomplete at longer periods where both the
sensitivity of transit surveys and radial velocity signals plummet. Even more
glaring is that the spectra of planets discovered with these indirect methods
are either inaccessible (radial velocity detections) or only available for a
small subclass of transiting planets with thick, clear atmospheres. Direct
detection can be used to discover and characterize the atmospheres of planets
at intermediate and wide separations, including non-transiting exoplanets.
Today, a small number of exoplanets have been directly imaged, but they
represent only a rare class of young, self-luminous super-Jovian-mass objects
orbiting tens to hundreds of AU from their host stars. Atmospheric
characterization of planets in the <5 AU regime, where radial velocity (RV)
surveys have revealed an abundance of other worlds, is technically feasible
with 30-m class apertures in combination with an advanced AO system,
coronagraph, and suite of spectrometers and imagers. There is a vast range of
unexplored science accessible through astrometry, photometry, and spectroscopy
of rocky planets, ice giants, and gas giants. In this whitepaper we will focus
on one of the most ambitious science goals --- detecting for the first time
habitable-zone rocky (<1.6 R_Earth) exoplanets in reflected light around nearby
M-dwarfsComment: 8 pages, 1 figure, Astro2020 Science White Pape
PECTINASE-MODIFIED RED GINSENG (GS-E3D) INHIBIT NF-ÃŽÅ¡B TRANSLOCATION AND NITRIC OXIDE PRODUCTION IN LIPOPOLYSACCHARIDE-STIMULATED RAW 264.7 CELLS
Objective: Red ginseng has been used as traditional medicines and functional foods in the world, because of its health benefits. The aim of this study was to elucidate the anti-inflammatory effect and mechanism of pectinase-modified red ginseng (GS-E3D) with a cellular model of lipopolysaccharide (LPS)-stimulated RAW264.7 cells.Methods: To study the anti-inflammatory effect of GS-E3D, the key inflammation mediators such as nitric oxide (NO),prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS), Cyclooxygenase-2 (COX-2), tumor necrosis factor (TNF-α), and interleukin (IL)-6 production as well as on nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) activation, were measured by using the enzyme linked immunosorbent assay (ELISA)and Western blotting.Results: GS-E3D potently inhibited TNF-α and IL-6 and also diminished NO over-production, which was accompanied by the down-regulation of iNOS expression. GS-E3D effectively suppressed LPS-induced NF-κB activation through inhibiting the hyper-phosphorylation and degradation of IκB-α and phosphorylation of p38, ERK1/2 and JNK in MAPK signaling pathway.Conclusion: GS-E3D has a potential to be as an anti-inflammatory agent for functional food or cosmetic materials targeting on the NF-κB p65 and MAPKs signaling pathways.Â
Ellipsoidal universe in the brane world
We study a scenario of the ellipsoidal universe in the brane world cosmology
with a cosmological constant in the bulk . From the five-dimensional Einstein
equations we derive the evolution equations for the eccentricity and the scale
factor of the universe, which are coupled to each other. It is found that if
the anisotropy of our universe is originated from a uniform magnetic field
inside the brane, the eccentricity decays faster in the bulk in comparison with
a four-dimensional ellipsoidal universe. We also investigate the ellipsoidal
universe in the brane-induced gravity and find the evolution equation for the
eccentricity which has a contribution determined by the four- and
five-dimensional Newton's constants. The role of the eccentricity is discussed
in explaining the quadrupole problem of the cosmic microwave background.Comment: 15 pages, 1 figure, Version 3, references added, contents expande
New Techniques for High-Contrast Imaging with ADI: the ACORNS-ADI SEEDS Data Reduction Pipeline
We describe Algorithms for Calibration, Optimized Registration, and Nulling
the Star in Angular Differential Imaging (ACORNS-ADI), a new, parallelized
software package to reduce high-contrast imaging data, and its application to
data from the SEEDS survey. We implement several new algorithms, including a
method to register saturated images, a trimmed mean for combining an image
sequence that reduces noise by up to ~20%, and a robust and computationally
fast method to compute the sensitivity of a high-contrast observation
everywhere on the field-of-view without introducing artificial sources. We also
include a description of image processing steps to remove electronic artifacts
specific to Hawaii2-RG detectors like the one used for SEEDS, and a detailed
analysis of the Locally Optimized Combination of Images (LOCI) algorithm
commonly used to reduce high-contrast imaging data. ACORNS-ADI is written in
python. It is efficient and open-source, and includes several optional features
which may improve performance on data from other instruments. ACORNS-ADI
requires minimal modification to reduce data from instruments other than
HiCIAO. It is freely available for download at
www.github.com/t-brandt/acorns-adi under a BSD license.Comment: 15 pages, 9 figures, accepted to ApJ. Replaced with accepted version;
mostly minor changes. Software update
Nonequilibrium Quantum Dynamics of Second Order Phase Transitions
We use the so-called Liouville-von Neumann (LvN) approach to study the
nonequilibrium quantum dynamics of time-dependent second order phase
transitions. The LvN approach is a canonical method that unifies the functional
Schr\"{o}dinger equation for the quantum evolution of pure states and the LvN
equation for the quantum description of mixed states of either equilibrium or
nonequilibrium. As nonequilibrium quantum mechanical systems we study a
time-dependent harmonic and an anharmonic oscillator and find the exact Fock
space and density operator for the harmonic oscillator and the nonperturbative
Gaussian Fock space and density operator for the anharmonic oscillator. The
density matrix and the coherent, thermal and coherent-thermal states are found
in terms of their classical solutions, for which the effective Hamiltonians and
equations of motion are derived. The LvN approach is further extended to
quantum fields undergoing time-dependent second order phase transitions. We
study an exactly solvable model with a finite smooth quench and find the
two-point correlation functions. Due to the spinodal instability of long
wavelength modes the two-point correlation functions lead to the
-scaling relation during the quench and the Cahn-Allen scaling
relation after the completion of quench. Further, after the finite
quench the domain formation shows a time-lag behavior at the cubic power of
quench period. Finally we study the time-dependent phase transition of a
self-interacting scalar field.Comment: discussion on back-reaction added, typos corrected, references added,
final version for PR
Orbital characterization of GJ1108A system, and comparison of dynamical mass with model-derived mass for resolved binaries
We report an orbital characterization of GJ1108Aab that is a low-mass binary
system in pre-main-sequence phase. Via the combination of astrometry using
adaptive optics and radial velocity measurements, an eccentric orbital solution
of =0.63 is obtained, which might be induced by the Kozai-Lidov mechanism
with a widely separated GJ1108B system. Combined with several observed
properties, we confirm the system is indeed young. Columba is the most probable
moving group, to which the GJ1108A system belongs, although its membership to
the group has not been established. If the age of Columba is assumed for
GJ1108A, the dynamical masses of both GJ1108Aa and GJ1108Ab ( and ) are more massive than what an
evolutionary model predicts based on the age and luminosities. We consider the
discrepancy in mass comparison can attribute to an age uncertainty; the system
is likely older than stars in Columba, and effects that are not implemented in
classical models such as accretion history and magnetic activity are not
preferred to explain the mass discrepancy. We also discuss the performance of
the evolutionary model by compiling similar low-mass objects in evolutionary
state based on the literature. Consequently, it is suggested that the current
model on average reproduces the mass of resolved low-mass binaries without any
significant offsets.Comment: Accepted in Ap
Direct Imaging of a Cold Jovian Exoplanet in Orbit around the Sun-like Star GJ 504
Several exoplanets have recently been imaged at wide separations of >10 AU
from their parent stars. These span a limited range of ages (<50 Myr) and
atmospheric properties, with temperatures of 800--1800 K and very red colors (J
- H > 0.5 mag), implying thick cloud covers. Furthermore, substantial model
uncertainties exist at these young ages due to the unknown initial conditions
at formation, which can lead to an order of magnitude of uncertainty in the
modeled planet mass. Here, we report the direct imaging discovery of a Jovian
exoplanet around the Sun-like star GJ 504, detected as part of the SEEDS
survey. The system is older than all other known directly-imaged planets; as a
result, its estimated mass remains in the planetary regime independent of
uncertainties related to choices of initial conditions in the exoplanet
modeling. Using the most common exoplanet cooling model, and given the system
age of 160 [+350, -60] Myr, GJ 504 b has an estimated mass of 4 [+4.5, -1.0]
Jupiter masses, among the lowest of directly imaged planets. Its projected
separation of 43.5 AU exceeds the typical outer boundary of ~30 AU predicted
for the core accretion mechanism. GJ 504 b is also significantly cooler (510
[+30, -20] K) and has a bluer color (J-H = -0.23 mag) than previously imaged
exoplanets, suggesting a largely cloud-free atmosphere accessible to
spectroscopic characterization. Thus, it has the potential of providing novel
insights into the origins of giant planets, as well as their atmospheric
properties.Comment: 20 pages, 12 figures, Accepted for publication in ApJ. Minor updates
from the version
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