4,977 research outputs found
Abell 1201: a Minor merger at second core passage
We present an analysis of the structures and dynamics of the merging cluster
Abell~1201, which has two sloshing cold fronts around a cooling core, and an
offset gas core approximately 500kpc northwest of the center. New Chandra and
XMM-Newton data reveal a region of enhanced brightness east of the offset core,
with breaks in surface brightness along its boundary to the north and east.
This is interpreted as a tail of gas stripped from the offset core. Gas in the
offset core and the tail is distinguished from other gas at the same distance
from the cluster center chiefly by having higher density, hence lower entropy.
In addition, the offset core shows marginally lower temperature and metallicity
than the surrounding area. The metallicity in the cool core is high and there
is an abrupt drop in metallicity across the southern cold front. We interpret
the observed properties of the system, including the placement of the cold
fronts, the offset core and its tail in terms of a simple merger scenario. The
offset core is the remnant of a merging subcluster, which first passed
pericenter southeast of the center of the primary cluster and is now close to
its second pericenter passage, moving at ~1000 km/s. Sloshing excited by the
merger gave rise to the two cold fronts and the disposition of the cold fronts
reveals that we view the merger from close to the plane of the orbit of the
offset core.Comment: accepted by Ap
Two-gap superconductivity with line nodes in CsCaFeAsF
We report the results of a muon-spin rotation (SR) experiment to
determine the superconducting ground state of the iron-based superconductor
CsCaFeAsF with K. This compound is
related to the fully-gapped superconductor CaCsFeAs, but here the
Ca-containing spacer layer is replaced with one containing CaF. The
temperature evolution of the penetration depth strongly suggests the presence
of line nodes and is best modelled by a system consisting of both an - and a
-wave gap. We also find a potentially magnetic phase which appears below
K but does not appear to compete with the superconductivity. This
compound contains the largest alkali atom in this family of superconductors and
our results yield a value for the in-plane penetration depth of
nm.Comment: 6 pages, 2 figure
The Differential Role of Human Cationic Trypsinogen (PRSS1) p.R122H Mutation in Hereditary and Nonhereditary Chronic Pancreatitis: A Systematic Review and Meta-Analysis.
Background:Environmental factors and genetic mutations have been increasingly recognized as risk factors for chronic pancreatitis (CP). The PRSS1 p.R122H mutation was the first discovered to affect hereditary CP, with 80% penetrance. We performed here a systematic review and meta-analysis to evaluate the associations of PRSS1 p.R122H mutation with CP of diverse etiology. Methods:The PubMed, EMBASE, and MEDLINE database were reviewed. The pooled odds ratio (OR) with 95% confidence intervals was used to evaluate the association of p.R122H mutation with CP. Initial analysis was conducted with all etiologies of CP, followed by a subgroup analysis for hereditary and nonhereditary CP, including alcoholic or idiopathic CP. Results:A total of eight case-control studies (1733 cases and 2415 controls) were identified and included. Overall, PRSS1 p.R122H mutation was significantly associated with an increased risk of CP (OR = 4.78[1.13-20.20]). Further analysis showed p.R122H mutation strongly associated with the increased risk of hereditary CP (OR = 65.52[9.09-472.48]) but not with nonhereditary CP, both alcoholic and idiopathic CP. Conclusions:Our study showing the differential role of p.R122H mutation in various etiologies of CP indicates that this complex disorder is likely influenced by multiple genetic factors as well as environmental factors
Towards incorporating the notion of feature shape in music and text retrieval
Extracted feature data augment information resources with concrete characterizations of their content, but only approximate to the meaningful high-level descriptions typically expected by digital musicology scholars (domain experts with some technological affinity, but with no expertise in signal processing or feature data). Feature shapes provide abstract aggregations of feature types which share common characteristics when applied in extraction workflows. We explore the feasibility of feature shape-based filtering and querying within a large audio dataset of live music performances, employing operation sequences as specified by the Audio Feature Ontology and Vocabulary. We further implement analogous semantic structures for the HathiTrust Extracted Feature Dataset to demonstrate the general applicability of feature shapes in music and text retrieval
Orbital stability of two circumbinary planets around misaligned eccentric binaries
With -body simulations we investigate the stability of tilted circumbinary
planetary systems consisting of two nonzero mass planets. The planets are
initially in circular orbits that are coplanar to each other, as would be
expected if they form in a flat but tilted circumbinary gas disc and decouple
from the disc within a time difference that is much less than the disc nodal
precession period. We constrain the parameters of stable multiple planet
circumbinary systems. Both planet-planet and planet-binary interactions can
cause complex planet tilt oscillations which can destabilise the orbits of one
or both planets. The system is considerably more unstable than the effects of
these individual interactions would suggest, due to the interplay between these
two interactions. The stability of the system is sensitive to the binary
eccentricity, the orbital tilt and the semi-major axes of the two circumbinary
planets. With an inner planet semi-major axis of , where is semi-major axis of the binary, the system is generally stable if the
outer planet is located at , beyond the 2:1 mean motion
resonance with the inner planet. For larger inner planet semi-major axis the
system is less stable because the von-Zeipel--Kozai--Lidov mechanism plays a
significant role, particularly for low binary-eccentricity cases. For the
unstable cases, the most likely outcome is that one planet is ejected and the
other remains bound on a highly eccentric orbit. Therefore we suggest that this
instability is an efficient mechanism for producing free-floating planets.Comment: 13 pages, 10 figure
Magic angle spinning (MAS) NMR linewidths in the presence of solid-state dynamics
In solid-state NMR, the magic angle spinning (MAS) technique fails to suppress anisotropic spin interactions fully if reorientational dynamics are present, resulting in a decay of the rotational-echo train in the time-domain signal. We show that a simple analytical model can be used to quantify this linebroadening effect as a function of the MAS frequency, reorientational rate constant, and magnitude of the inhomogeneous anisotropic broadening. We compare this model with other theoretical approaches and with exact computer simulations, and show how it may be used to estimate rate constants from experimental NMR data
Tilted circumbinary planetary systems as efficient progenitors of free-floating planets
The dominant mechanism for generating free-floating planets has so far
remained elusive. One suggested mechanism is that planets are ejected from
planetary systems due to planet-planet interactions. However, instability
around a single star requires a very compactly spaced planetary system. We find
that around binary star systems instability can occur even with widely
separated planets that are on tilted orbits relative to the binary orbit due to
combined effects of planet-binary and planet-planet interactions, especially if
the binary is on an eccentric orbit. We investigate the orbital stability of
planetary systems with various planet masses and architectures. We find that
the stability of the system depends upon the mass of the highest mass planet.
The order of the planets in the system does not significantly affect stability
but, generally, the most massive planet remains stable and the lower mass
planets are ejected. The minimum planet mass required to trigger the
instability is about that of Neptune for a circular orbit binary and a
super-Earth of about Earth masses for highly eccentric binaries. Hence, we
suggest that planet formation around misaligned binaries can be an efficient
formation mechanism for free-floating planets. While most observed
free-floating planets are giant planets, we predict that there should be more
low-mass free floating planets that are as yet unobserved than higher mass
planets.Comment: 10 pages, 2 figure
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