10,412 research outputs found
Mapping the Polarization of the Radio-Loud Ly Nebula B3 J2330+3927
Lya nebulae, or "Lya blobs", are extended (up to ~100 kpc), bright (L[Lya] >
10^43 erg/s) clouds of Lya emitting gas that tend to lie in overdense regions
at z ~ 2--5. The origin of the Lya emission remains unknown, but recent
theoretical work suggests that measuring the polarization might discriminate
among powering mechanisms. Here we present the first narrowband, imaging
polarimetry of a radio-loud Lya nebula, B3 J2330+3927 at z=3.09, with an
embedded active galactic nucleus (AGN). The AGN lies near the blob's Lya
emission peak and its radio lobes align roughly with the blob's major axis.
With the SPOL polarimeter on the 6.5m MMT telescope, we map the total (Lya +
continuum) polarization in a grid of circular apertures of radius 0.6"
(4.4kpc), detecting a significant (>2sigma) polarization fraction P in nine
apertures and achieving strong upper-limits (as low as 2%) elsewhere. P
increases from <2% at ~5kpc from the blob center to ~17% at ~15-25kpc. The
detections are distributed asymmetrically, roughly along the nebula's major
axis. The polarization angles theta are mostly perpendicular to this axis.
Comparing the Lya flux to that of the continuum, and conservatively assuming
that the continuum is highly polarized (20-100%) and aligned with the total
polarization, we place lower limits on the polarization of the Lya emission
P(Lya) ranging from no significant polarization at ~5 kpc from the blob center
to ~ 3--17% at 10--25kpc. Like the total polarization, the Lya polarization
detections occur more often along the blob's major axis.Comment: 9 pages, 7 figures, accepted for publication in Ap
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Death-associated protein kinase 1 has a critical role in aberrant tau protein regulation and function
The presence of tangles composed of phosphorylated tau is one of the neuropathological hallmarks of Alzheimer's disease (AD). Tau, a microtubule (MT)-associated protein, accumulates in AD potentially as a result of posttranslational modifications, such as hyperphosphorylation and conformational changes. However, it has not been fully understood how tau accumulation and phosphorylation are deregulated. In the present study, we identified a novel role of death-associated protein kinase 1 (DAPK1) in the regulation of the tau protein. We found that hippocampal DAPK1 expression is markedly increased in the brains of AD patients compared with age-matched normal subjects. DAPK1 overexpression increased tau protein stability and phosphorylation at multiple AD-related sites. In contrast, inhibition of DAPK1 by overexpression of a DAPK1 kinase-deficient mutant or by genetic knockout significantly decreased tau protein stability and abolished its phosphorylation in cell cultures and in mice. Mechanistically, DAPK1-enhanced tau protein stability was mediated by Ser71 phosphorylation of Pin1, a prolyl isomerase known to regulate tau protein stability, phosphorylation, and tau-related pathologies. In addition, inhibition of DAPK1 kinase activity significantly increased the assembly of MTs and accelerated nerve growth factor-mediated neurite outgrowth. Given that DAPK1 has been genetically linked to late onset AD, these results suggest that DAPK1 is a novel regulator of tau protein abundance, and that DAPK1 upregulation might contribute to tau-related pathologies in AD. Therefore, we offer that DAPK1 might be a novel therapeutic target for treating human AD and other tau-related pathologies
A particle-number-conserving Bogoliubov method which demonstrates the validity of the time-dependent Gross-Pitaevskii equation for a highly condensed Bose gas
The Bogoliubov method for the excitation spectrum of a Bose-condensed gas is
generalized to apply to a gas with an exact large number of particles.
This generalization yields a description of the Schr\"odinger picture field
operators as the product of an annihilation operator for the total number
of particles and the sum of a ``condensate wavefunction'' and a phonon
field operator in the form when the field operator acts on the N particle subspace. It
is then possible to expand the Hamiltonian in decreasing powers of ,
an thus obtain solutions for eigenvalues and eigenstates as an asymptotic
expansion of the same kind. It is also possible to compute all matrix elements
of field operators between states of different N.Comment: RevTeX, 11 page
Visual Affect Around the World: A Large-scale Multilingual Visual Sentiment Ontology
Every culture and language is unique. Our work expressly focuses on the
uniqueness of culture and language in relation to human affect, specifically
sentiment and emotion semantics, and how they manifest in social multimedia. We
develop sets of sentiment- and emotion-polarized visual concepts by adapting
semantic structures called adjective-noun pairs, originally introduced by Borth
et al. (2013), but in a multilingual context. We propose a new
language-dependent method for automatic discovery of these adjective-noun
constructs. We show how this pipeline can be applied on a social multimedia
platform for the creation of a large-scale multilingual visual sentiment
concept ontology (MVSO). Unlike the flat structure in Borth et al. (2013), our
unified ontology is organized hierarchically by multilingual clusters of
visually detectable nouns and subclusters of emotionally biased versions of
these nouns. In addition, we present an image-based prediction task to show how
generalizable language-specific models are in a multilingual context. A new,
publicly available dataset of >15.6K sentiment-biased visual concepts across 12
languages with language-specific detector banks, >7.36M images and their
metadata is also released.Comment: 11 pages, to appear at ACM MM'1
Clonal and genetic structure of Iris odaesanensis and Iris rossii (Iridaceae): insights of the Baekdudaegan Mountains as a glacial refugium for boreal and temperate plants
The main Korean mountain range that stretches from north to south (the Baekdudaegan) has been suggested to harbor an important glacial refugium for boreal and temperate plant species. Under this scenario, we expect high levels of within-population genetic variation and low or moderate degree of among-population differentiation within these species. To test this hypothesis, we examined clonal diversity and levels of allozyme diversity in the boreal Iris odaesanensis and in its temperate congener Iris rossii. In addition, we compiled data on boreal and temperate species whose distribution in the Korean Peninsula is mostly centered in the Baekdudaegan to determine if there is a common pattern. We found lower clonal diversity in I. odaesanensis compared to I. rossii. Both studied species maintained high levels of genetic variation as well as a moderate genetic differentiation (%P = 52.5 and 47.5, A = 1.70 and 1.58, H e = 0.158 and 0.150, and F ST = 0.196 and 0.189 for I. odaesanensis and I. rossii, respectively), in line with what occurs for the species distributed on the Baekdudaegan (n = 14, %P = 46.7, A = 1.73, H e = 0.161, and F ST = 0.190). This study strongly suggests that the Baekdudaegan may have acted as a refugium for boreal and temperate species, in a similar way to the southern Appalachians in the eastern United States
Perturbative Expansion around the Gaussian Effective Potential of the Fermion Field Theory
We have extended the perturbative expansion method around the Gaussian
effective action to the fermionic field theory, by taking the 2-dimensional
Gross-Neveu model as an example. We have computed both the zero temperature and
the finite temperature effective potentials of the Gross-Neveu model up to the
first perturbative correction terms, and have found that the critical
temperature, at which dynamically broken symmetry is restored, is significantly
improved for small value of the flavour number.Comment: 14pages, no figures, other comments Typographical errors are
corrected and new references are adde
Prospects for p-wave paired BCS states of fermionic atoms
We present theoretical prospects for creating p-wave paired BCS states of
magnetic trapped fermionic atoms. Based on our earlier proposal of using dc
electric fields to control both the strength and anisotropic characteristic of
atom-atom interaction and our recently completed multi-channel atomic collision
calculations we discover that p-wave pairing with K and Rb
in the low field seeking maximum spin polarized state represent excellent
choices for achieving superfluid BCS states; and may be realizable with current
technology in laser cooling, magnetic trapping, and evaporative/sympathetic
cooling, provided the required strong electric field can be applied. We also
comment on the prospects of similar p-wave paired BCS states in Li, and
more generally on creating other types exotic BCS states. Our study will open a
new area in the vigorous pursuit to create a quantum degenerate fermionic atom
vapor.Comment: to be publishe
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