2,055 research outputs found
Finding the Needles in the Haystacks: High-Fidelity Models of the Modern and Archean Solar System for Simulating Exoplanet Observations
We present two state-of-the-art models of the solar system, one corresponding
to the present day and one to the Archean Eon 3.5 billion years ago. Each model
contains spatial and spectral information for the star, the planets, and the
interplanetary dust, extending to 50 AU from the sun and covering the
wavelength range 0.3 to 2.5 micron. In addition, we created a spectral image
cube representative of the astronomical backgrounds that will be seen behind
deep observations of extrasolar planetary systems, including galaxies and Milky
Way stars. These models are intended as inputs to high-fidelity simulations of
direct observations of exoplanetary systems using telescopes equipped with
high-contrast capability. They will help improve the realism of observation and
instrument parameters that are required inputs to statistical observatory yield
calculations, as well as guide development of post-processing algorithms for
telescopes capable of directly imaging Earth-like planets.Comment: Accepted for publication in PAS
Resolved Mid-IR Emission in the Narrow Line Region of NGC 4151
We present subarcsecond resolution mid infrared images of NGC 4151 at 10.8
micron and 18.2 micron. These images were taken with the University of Florida
mid-IR camera/spectrometer OSCIR at the Gemini North 8-m telescope. We resolve
emission at both 10.8 micron and 18.2 micron extending ~ 3.5" across at a P.A.
of ~ 60 degrees. This coincides with the the narrow line region of NGC 4151 as
observed in [OIII] by the Hubble Space Telescope. The most likely explanation
for this extended mid-IR emission is dust in the narrow line region heated by a
central engine. We find no extended emission associated with the proposed torus
and place an upper limit on its mid-IR size of less than or equal to ~ 35 pc.Comment: accepted for publication in the Astrophysical Journal, 19 pages
including 5 figure
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Observation of an α-synuclein liquid droplet state and its maturation into Lewy body-like assemblies.
Misfolded α-synuclein is a major component of Lewy bodies, which are a hallmark of Parkinson's disease (PD). A large body of evidence shows that α-synuclein can aggregate into amyloid fibrils, but the relationship between α-synuclein self-assembly and Lewy body formation remains unclear. Here, we show, both in vitro and in a Caenorhabditis elegans model of PD, that α-synuclein undergoes liquid‒liquid phase separation by forming a liquid droplet state, which converts into an amyloid-rich hydrogel with Lewy-body-like properties. This maturation process towards the amyloid state is delayed in the presence of model synaptic vesicles in vitro. Taken together, these results suggest that the formation of Lewy bodies may be linked to the arrested maturation of α-synuclein condensates in the presence of lipids and other cellular components.Wellcome Trust (065807/Z/01/Z) (203249/Z/16/Z).
Also, the UK Medical Research Council (MRC) (MR/K02292X/1), Alzheimer Research UK (ARUK) (ARUK-PG013-14), Michael J Fox Foundation (16238) and from Infinitus China Ltd
Observation of an α-synuclein liquid droplet state and its maturation into Lewy body-like assemblies.
Misfolded α-synuclein is a major component of Lewy bodies, which are a hallmark of Parkinson's disease (PD). A large body of evidence shows that α-synuclein can aggregate into amyloid fibrils, but the relationship between α-synuclein self-assembly and Lewy body formation remains unclear. Here, we show, both in vitro and in a Caenorhabditis elegans model of PD, that α-synuclein undergoes liquid‒liquid phase separation by forming a liquid droplet state, which converts into an amyloid-rich hydrogel with Lewy-body-like properties. This maturation process towards the amyloid state is delayed in the presence of model synaptic vesicles in vitro. Taken together, these results suggest that the formation of Lewy bodies may be linked to the arrested maturation of α-synuclein condensates in the presence of lipids and other cellular components.Wellcome Trust (065807/Z/01/Z) (203249/Z/16/Z).
Also, the UK Medical Research Council (MRC) (MR/K02292X/1), Alzheimer Research UK (ARUK) (ARUK-PG013-14), Michael J Fox Foundation (16238) and from Infinitus China Ltd
Intensity of Th and Pa scavenging partitioned by particle chemistry in the North Atlantic Ocean
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Marine Chemistry 170 (2015): 49-60, doi:10.1016/j.marchem.2015.01.006.The natural radionuclides 231Pa and 230Th are incorporated into the marine sediment record by
scavenging, or adsorption to various particle types, via chemical reactions that are not fully
understood. Because these isotopes have potential value in tracing several oceanographic
processes, we investigate the nature of scavenging using trans-Atlantic measurements of
dissolved (<0.45 μm) and particulate (0.8-51 μm) 231Pa and 230Th, together with major particle
composition. We find widespread impact of intense scavenging by authigenic Fe/Mn
(hydr)oxides, in the form of hydrothermal particles emanating from the Mid-Atlantic ridge and
particles resuspended from reducing conditions near the seafloor off the coast of West Africa.
Biogenic opal was not found to be a significant scavenging phase for either element in this
sample set, essentially because of its low abundance and small dynamic range at the studied
sites. Distribution coefficients in shallow (< 200 m) depths are anomalously low which suggests
either the unexpected result of a low scavenging intensity for organic matter or that, in water
masses containing abundant organic-rich particles, a greater percentage of radionuclides exist in
the colloidal or complexed phase. In addition to particle concentration, the oceanic distribution
of particle types likely plays a significant role in the ultimate distribution of sedimentary 230Th
and 231Pa.Cruise management for GA03 was funded by the U. S. National Science Foundation to W.
Jenkins (OCE-0926423), E. Boyle (OCE-0926204), and G. Cutter (OCE-0926092). Radionuclide
studies were supported by NSF (OCE-0927064 to LDEO, OCE-0926860 to WHOI, OCE-
0927757 to URI, and OCE-0927754 to UMN). Additional support came from the European
Research Council (278705) to LFR and the Ford Foundation Predoctoral Fellowship to SMV.
Particle studies were supported by NSF OCE-0963026 to PJL
A Hexagonal Theory of Flavor
We construct a supersymmetric theory of flavor based on the discrete gauge
group (D_6)^2, where D_6 describes the symmetry of a regular hexagon under
proper rotations in three dimensions. The representation structure of the group
allows one to distinguish the third from the lighter two generations of matter
fields, so that in the symmetry limit only the top quark Yukawa coupling is
allowed and scalar superpartners of the first two generations are degenerate.
Light fermion Yukawa couplings arise from a sequential breaking of the flavor
symmetry, and supersymmetric flavor-changing processes remain adequately
suppressed. We contrast our model with others based on non-Abelian discrete
gauge symmetries described in the literature, and discuss the challenges in
constructing more minimal flavor models based on this approach.Comment: 19 pages, ReVTeX, 1 eps figur
Honey bee foraging distance depends on month and forage type
To investigate the distances at which honey bee foragers collect nectar and pollen, we analysed 5,484 decoded waggle dances made to natural forage sites to determine monthly foraging distance for each forage type. Firstly, we found significantly fewer overall dances made for pollen (16.8 %) than for non-pollen, presumably nectar (83.2 %; P < 2.2 × 10−23). When we analysed distance against month and forage type, there was a significant interaction between the two factors, which demonstrates that in some months, one forage type is collected at farther distances, but this would reverse in other months. Overall, these data suggest that distance, as a proxy for forage availability, is not significantly and consistently driven by need for one type of forage over the other
Political branding: sense of identity or identity crisis? An investigation of the transfer potential of the brand identity prism to the UK Conservative Party
Brands are strategic assets and key to achieving a competitive advantage. Brands can be seen as a heuristic device, encapsulating a series of values that enable the consumer to make quick and efficient choices. More recently, the notion of a political brand and the rhetoric of branding have been widely adopted by many political parties as they seek to differentiate themselves, and this has led to an emerging interest in the idea of the political brand. Therefore, this paper examines the UK Conservative Party brand under David Cameron’s leadership and examines the applicability of Kapferer’s brand identity prism to political branding. This paper extends and operationalises the brand identity prism into a ‘political brand identity network’ which identifies the inter-relatedness of the components of the corporate political brand and the candidate political brand. Crucial for practitioners, this model can demonstrate how the brand is presented and communicated to the electorate and serves as a useful mechanism to identify consistency within the corporate and candidate political brands
IR and UV Galaxies at z=0.6 -- Evolution of Dust Attenuation and Stellar Mass as Revealed by SWIRE and GALEX
We study dust attenuation and stellar mass of star-forming
galaxies using new SWIRE observations in IR and GALEX observations in UV. Two
samples are selected from the SWIRE and GALEX source catalogs in the
SWIRE/GALEX field ELAIS-N1-00 ( deg). The UV selected sample
has 600 galaxies with photometric redshift (hereafter photo-z) and NUV (corresponding to \rm L_{FUV} \geq 10^{9.6} L_\sun).
The IR selected sample contains 430 galaxies with mJy
(\rm L_{dust} \geq 10^{10.8} L_\sun) in the same photo-z range. It is found
that the mean ratios of the z=0.6 UV galaxies are
consistent with that of their z=0 counterparts of the same . For
IR galaxies, the mean ratios of the z=0.6 LIRGs (\rm
L_{dust} \sim 10^{11} L_\sun) are about a factor of 2 lower than local LIRGs,
whereas z=0.6 ULIRGs (\rm L_{dust} \sim 10^{12} L_\sun) have the same mean
ratios as their local counterparts. This is consistent
with the hypothesis that the dominant component of LIRG population has changed
from large, gas rich spirals at z to major-mergers at z=0. The stellar
mass of z=0.6 UV galaxies of \rm L_{FUV} \leq 10^{10.2} L_\sun is about a
factor 2 less than their local counterparts of the same luminosity, indicating
growth of these galaxies. The mass of z=0.6 UV lunmous galaxies (UVLGs: \rm
L_{FUV} > 10^{10.2} L_\sun) and IR selected galaxies, which are nearly
exclusively LIRGs and ULIRGs, is the same as their local counterparts.Comment: 27 pages, 8 figures, to be published in the Astrophysical Journal
Supplement series dedicated to GALEX result
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