1,251 research outputs found
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Follow-up examination of linkage and association to chromosome 1q43 in multiple sclerosis.
Multiple sclerosis (MS) is a debilitating neuroimmunological and neurodegenerative disease affecting >4,00,000 individuals in the United States. Population and family-based studies have suggested that there is a strong genetic component. Numerous genomic linkage screens have identified regions of interest for MS loci. Our own second-generation genome-wide linkage study identified a handful of non-major histocompatibility complex regions with suggestive linkage. Several of these regions were further examined using single-nucleotide polymorphisms (SNPs) with average spacing between SNPs of approximately 1.0 Mb in a dataset of 173 multiplex families. The results of that study provided further evidence for the involvement of the chromosome 1q43 region. This region is of particular interest given linkage evidence in studies of other autoimmune and inflammatory diseases including rheumatoid arthritis and systemic lupus erythematosus. In this follow-up study, we saturated the region with approximately 700 SNPs (average spacing of 10 kb per SNP) in search of disease-associated variation within this region. We found preliminary evidence to suggest that common variation within the RGS7 locus may be involved in disease susceptibility
The spectral variability of FSRQs
The optical variability of 29 flat spectrum radio quasars in SDSS Stripe 82
region are investigated by using DR7 released multi-epoch data. All FSRQs show
variations with overall amplitude ranging from 0.24 mag to 3.46 mag in
different sources. About half of FSRQs show a bluer-when-brighter trend, which
is commonly observed for blazars. However, only one source shows a
redder-when-brighter trend, which implies it is rare in FSRQs. In this source,
the thermal emission may likely be responsible for the spectral behavior.Comment: 4 pages, 1 figure, to be published in Journal of Astrophysics and
Astronomy, as a proceeding paper of the conference "Multiwavelength
Variability of Blazars", Guangzhou, China, September 22-24, 201
Speculation on the origin of sub-baseline excursions of CH4 at Cape Grim
The Advanced Global Atmospheric Gases Experiment (AGAGE) program has historically measured in situ
methane (CH4
) at Cape Grim via gas chromatography with flame ionization detection (GC-FID) in 40 minutely
grab samples. By adding continuous, high precision in situ measurements of CH4
(Picarro cavity ring-down
spectroscopy [CRDS]) at both Cape Grim, Tasmania, and Casey, Antarctica, a new feature has become apparent
in the Cape Grim CH4
record. During the austral summer (December to February), the Cape Grim CH4
record
periodically drops below baseline. For example, in Figure 1, a number of sustained episodes of depressed CH4
concentration can be seen below the baseline selected data shown in red. Notably, these episodes are also seen
in the GC-FID record.
In this presentation, we examine these sub-baseline excursions of CH4
. In conjunction with meteorology and a
variety of other chemical species measured at Cape Grim, including radon, ozone, hydrogen and ethane, we speculate on a number of possible mechanisms that might be responsible for these dips in CH4 mixing ratio
Effects of temperature on thick branes and the fermion (quasi-)localization
Following Campos's work [Phys. Rev. Lett. 88, 141602 (2002)], we investigate
the effects of temperature on flat, de Sitter (dS), and anti-de Following
Campos's work [Phys. Rev. Lett. \textbf{88}, 141602 (2002)], we investigate the
effects of temperature on flat, de Sitter (dS), and anti-de Sitter (AdS) thick
branes in five-dimensional (5D) warped spacetime, and on the fermion
(quasi-)localization. First, in the case of flat brane, when the critical
temperature reaches, the solution of the background scalar field and the warp
factor is not unique. So the thickness of the flat thick brane is uncertain at
the critical value of the temperature parameter, which is found to be lower
than the one in flat 5D spacetime. The mass spectra of the fermion Kaluza-Klein
(KK) modes are continuous, and there is a series of fermion resonances. The
number and lifetime of the resonances are finite and increase with the
temperature parameter, but the mass of the resonances decreases with the
temperature parameter. Second, in the case of dS brane, we do not find such a
critical value of the temperature parameter. The mass spectra of the fermion KK
modes are also continuous, and there is a series of fermion resonances. The
effects of temperature on resonance number, lifetime, and mass are the same
with the case of flat brane. Last, in the case of AdS brane, {the critical
value of the temperature parameter can less or greater than the one in the flat
5D spacetime.} The spectra of fermion KK modes are discrete, and the mass of
fermion KK modes does not decrease monotonically with increasing temperature
parameter.Comment: 24 pages, 15 figures, published versio
High star formation rates as the origin of turbulence in early and modern disk galaxies
High spatial and spectral resolution observations of star formation and
kinematics in early galaxies have shown that two-thirds are massive rotating
disk galaxies with the remainder being less massive non-rotating objects. The
line of sight averaged velocity dispersions are typically five times higher
than in today's disk galaxies. This has suggested that
gravitationally-unstable, gas-rich disks in the early Universe are fuelled by
cold, dense accreting gas flowing along cosmic filaments and penetrating hot
galactic gas halos. However these accreting flows have not been observed, and
cosmic accretion cannot power the observed level of turbulence. Here we report
on a new sample of rare high-velocity-dispersion disk galaxies we have
discovered in the nearby Universe where cold accretion is unlikely to drive
their high star-formation rates. We find that the velocity dispersion is most
fundamentally correlated with their star-formation rates, and not their mass
nor gas fraction, which leads to a new picture where star formation itself is
the energetic driver of galaxy disk turbulence at all cosmic epochs.Comment: 9 pages, 2 figures, Supplimentary Info available at:
http://pulsar.swin.edu.au/~agreen/nature/sigma_mean_arXiv.pdf. Accepted for
publication in Natur
The Worldvolume Action of Kink Solitons in AdS Spacetime
A formalism is presented for computing the higher-order corrections to the
worldvolume action of co-dimension one solitons. By modifying its potential, an
explicit "kink" solution of a real scalar field in AdS spacetime is found. The
formalism is then applied to explicitly compute the kink worldvolume action to
quadratic order in two expansion parameters--associated with the hypersurface
fluctuation length and the radius of AdS spacetime respectively. Two
alternative methods are given for doing this. The results are expressed in
terms of the trace of the extrinsic curvature and the intrinsic scalar
curvature. In addition to conformal Galileon interactions, we find a
non-Galileon term which is never sub-dominant. This method can be extended to
any conformally flat bulk spacetime.Comment: 32 pages, 3 figures, typos corrected and additional comments adde
Kinetic modelling of competition and depletion of shared miRNAs by competing endogenous RNAs
Non-conding RNAs play a key role in the post-transcriptional regulation of
mRNA translation and turnover in eukaryotes. miRNAs, in particular, interact
with their target RNAs through protein-mediated, sequence-specific binding,
giving rise to extended and highly heterogeneous miRNA-RNA interaction
networks. Within such networks, competition to bind miRNAs can generate an
effective positive coupling between their targets. Competing endogenous RNAs
(ceRNAs) can in turn regulate each other through miRNA-mediated crosstalk.
Albeit potentially weak, ceRNA interactions can occur both dynamically,
affecting e.g. the regulatory clock, and at stationarity, in which case ceRNA
networks as a whole can be implicated in the composition of the cell's
proteome. Many features of ceRNA interactions, including the conditions under
which they become significant, can be unraveled by mathematical and in silico
models. We review the understanding of the ceRNA effect obtained within such
frameworks, focusing on the methods employed to quantify it, its role in the
processing of gene expression noise, and how network topology can determine its
reach.Comment: review article, 29 pages, 7 figure
Nonlinear Dynamics of 3D Massive Gravity
We explore the nonlinear classical dynamics of the three-dimensional theory
of "New Massive Gravity" proposed by Bergshoeff, Hohm and Townsend. We find
that the theory passes remarkably highly nontrivial consistency checks at the
nonlinear level. In particular, we show that: (1) In the decoupling limit of
the theory, the interactions of the helicity-0 mode are described by a single
cubic term -- the so-called cubic Galileon -- previously found in the context
of the DGP model and in certain 4D massive gravities. (2) The conformal mode of
the metric coincides with the helicity-0 mode in the decoupling limit. Away
from this limit the nonlinear dynamics of the former is described by a certain
generalization of Galileon interactions, which like the Galileons themselves
have a well-posed Cauchy problem. (3) We give a non-perturbative argument based
on the presence of additional symmetries that the full theory does not lead to
any extra degrees of freedom, suggesting that a 3D analog of the 4D
Boulware-Deser ghost is not present in this theory. Last but not least, we
generalize "New Massive Gravity" and construct a class of 3D cubic order
massive models that retain the above properties.Comment: 21 page
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The influence of the atmospheric boundary layer on nocturnal layers of noctuids and other moths migrating over southern Britain
Insects migrating at high altitude over southern Britain have been continuously monitored by automatically-operating, vertical-looking radars over a period of several years. During some occasions in the summer months, the migrants were observed to form well-defined layer concentrations, typically at heights of 200-400 m, in the stable night-time atmosphere. Under these conditions, insects are likely to have control over their vertical movements and are selecting flight heights which are favourable for long-range migration. We therefore investigated the factors influencing the formation of these insect layers by comparing radar measurements of the vertical distribution of insect density with meteorological profiles generated by the UK Met. Office’s Unified Model (UM). Radar-derived measurements of mass and displacement speed, along with data from Rothamsted Insect Survey light traps provided information on the identity of the migrants. We present here three case studies where noctuid and pyralid moths contributed substantially to the observed layers. The major meteorological factors influencing the layer concentrations appeared to be: (a) the altitude of the warmest air, (b) heights corresponding to temperature preferences or thresholds for sustained migration and (c), on nights when air temperatures are relatively high, wind-speed maxima associated with the nocturnal jet. Back-trajectories indicated that layer duration may have been determined by the distance to the coast. Overall, the unique combination of meteorological data from the UM and insect data from entomological radar described here show considerable promise for systematic studies of high-altitude insect layering
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