449 research outputs found
Knot invariants in lens spaces
In this survey we summarize results regarding the Kauffman bracket, HOMFLYPT,
Kauffman 2-variable and Dubrovnik skein modules, and the Alexander polynomial
of links in lens spaces, which we represent as mixed link diagrams. These
invariants generalize the corresponding knot polynomials in the classical case.
We compare the invariants by means of the ability to distinguish between some
difficult cases of knots with certain symmetries
An Evolving Entropy Floor in the Intracluster Gas?
Non-gravitational processes, such as feedback from galaxies and their active
nuclei, are believed to have injected excess entropy into the intracluster gas,
and therefore to have modified the density profiles in galaxy clusters during
their formation. Here we study a simple model for this so-called preheating
scenario, and ask (i) whether it can simultaneously explain both global X-ray
scaling relations and number counts of galaxy clusters, and (ii) whether the
amount of entropy required evolves with redshift. We adopt a baseline entropy
profile that fits recent hydrodynamic simulations, modify the hydrostatic
equilibrium condition for the gas by including approx. 20% non-thermal pressure
support, and add an entropy floor K_0 that is allowed to vary with redshift. We
find that the observed luminosity-temperature (L-T) relations of low-redshift
(z=0.05) HIFLUGCS clusters and high-redshift (z=0.8) WARPS clusters are best
simultaneously reproduced with an evolving entropy floor of
K_0(z)=341(1+z)^{-0.83}h^{-1/3} keV cm^2. If we restrict our analysis to the
subset of bright (kT > 3 keV) clusters, we find that the evolving entropy floor
can mimic a self-similar evolution in the L-T scaling relation. This degeneracy
with self-similar evolution is, however, broken when (0.5 < kT < 3 keV)
clusters are also included. The approx. 60% entropy increase we find from z=0.8
to z=0.05 is roughly consistent with that expected if the heating is provided
by the evolving global quasar population. Using the cosmological parameters
from the WMAP 3-year data with sigma_8=0.76, our best-fit model underpredicts
the number counts of the X-ray galaxy clusters compared to those derived from
the 158 deg^2 ROSAT PSPC survey. Treating sigma_8 as a free parameter, we find
a best-fit value of sigma_8=0.80+/- 0.02.Comment: 14 emulateapj pages with 9 figures, submitted to Ap
Three-dimensional Multi-probe Analysis of the Galaxy Cluster A1689
We perform a 3D multi-probe analysis of the rich galaxy cluster A1689 by
combining improved weak-lensing data from new BVRi'z' Subaru/Suprime-Cam
observations with strong-lensing, X-ray, and Sunyaev-Zel'dovich effect (SZE)
data sets. We reconstruct the projected matter distribution from a joint
weak-lensing analysis of 2D shear and azimuthally integrated magnification
constraints, the combination of which allows us to break the mass-sheet
degeneracy. The resulting mass distribution reveals elongation with axis ratio
~0.7 in projection. When assuming a spherical halo, our full weak-lensing
analysis yields a projected concentration of
(), consistent with and improved from earlier weak-lensing
work. We find excellent consistency between weak and strong lensing in the
region of overlap. In a parametric triaxial framework, we constrain the
intrinsic structure and geometry of the matter and gas distributions, by
combining weak/strong lensing and X-ray/SZE data with minimal geometric
assumptions. We show that the data favor a triaxial geometry with minor-major
axis ratio 0.39+/-0.15 and major axis closely aligned with the line of sight
(22+/-10 deg). We obtain and
, which overlaps with the tail of the predicted
distribution. The shape of the gas is rounder than the underlying matter but
quite elongated with minor-major axis ratio 0.60+/-0.14. The gas mass fraction
within 0.9Mpc is 10^{+3}_{-2}%. The thermal gas pressure contributes to ~60% of
the equilibrium pressure, indicating a significant level of non-thermal
pressure support. When compared to Planck's hydrostatic mass estimate, our
lensing measurements yield a spherical mass ratio of and with and without corrections for lensing projection
effects, respectively.Comment: Accepted by ApJ. Minor textual changes to improve clarity (e.g., 5.
HST STRONG-LENSING ANALYSIS). 26 pages, 17 figures. A version with
high-resolution figures is available at
http://www.asiaa.sinica.edu.tw/~keiichi/upfiles/Umetsu15/umetsu15.pd
Erratum: This article corrects: Best practices for evaluation and treatment of agitated children and adolescents (Beta) in the emergency department: Consensus statement of the American Association for Emergency psychiatry (Western Journal of Emergency Medicine (2019) 20: 2 (409-419) DOI: 10.5811/westjem.2019.1.41344)
Application of a Self-Similar Pressure Profile to Sunyaev-Zel'dovich Effect Data from Galaxy Clusters
We investigate the utility of a new, self-similar pressure profile for
fitting Sunyaev-Zel'dovich (SZ) effect observations of galaxy clusters. Current
SZ imaging instruments - such as the Sunyaev-Zel'dovich Array (SZA) - are
capable of probing clusters over a large range in physical scale. A model is
therefore required that can accurately describe a cluster's pressure profile
over a broad range of radii, from the core of the cluster out to a significant
fraction of the virial radius. In the analysis presented here, we fit a radial
pressure profile derived from simulations and detailed X-ray analysis of
relaxed clusters to SZA observations of three clusters with exceptionally high
quality X-ray data: A1835, A1914, and CL J1226.9+3332. From the joint analysis
of the SZ and X-ray data, we derive physical properties such as gas mass, total
mass, gas fraction and the intrinsic, integrated Compton y-parameter. We find
that parameters derived from the joint fit to the SZ and X-ray data agree well
with a detailed, independent X-ray-only analysis of the same clusters. In
particular, we find that, when combined with X-ray imaging data, this new
pressure profile yields an independent electron radial temperature profile that
is in good agreement with spectroscopic X-ray measurements.Comment: 28 pages, 6 figures, accepted by ApJ for publication (probably April
2009
The Massive and Distant Clusters of WISE Survey: SZ effect Verification with the Atacama Compact Array -- Localization and Cluster Analysis
The Massive and Distant Clusters of WISE Survey (MaDCoWS) provides a catalog
of high-redshift () infrared-selected galaxy
clusters. However, the verification of the ionized intracluster medium,
indicative of a collapsed and nearly virialized system, is made challenging by
the high redshifts of the sample members. The main goal of this work is to test
the capabilities of the Atacama Compact Array (ACA; also known as the Morita
Array) Band 3 observations, centered at about 97.5 GHz, to provide robust
validation of cluster detections via the thermal Sunyaev-Zeldovich (SZ) effect.
Using a pilot sample that comprises ten MaDCoWS galaxy clusters, accessible to
ACA and representative of the median sample richness, we infer the masses of
the selected galaxy clusters and respective detection significance by means of
a Bayesian analysis of the interferometric data. Our test of the "Verification
with the ACA - Localization and Cluster Analysis" (VACA LoCA) program
demonstrates that the ACA can robustly confirm the presence of the virialized
intracluster medium in galaxy clusters previously identified in full-sky
surveys. In particular, we obtain a significant detection of the SZ effect for
seven out of the ten VACA LoCA clusters. We note that this result is
independent of the assumed pressure profile. However, the limited angular
dynamic range of the ACA in Band 3 alone, short observational integration
times, and possible contamination from unresolved sources limit the detailed
characterization of the cluster properties and the inference of the cluster
masses within scales appropriate for the robust calibration of mass-richness
scaling relations.Comment: 19 pages (including appendices), 14 figures, and 4 tables; accepted
for publication in A&
Galaxy Cluster Scaling Relations between Bolocam Sunyaev-Zel'dovich Effect and Chandra X-ray Measurements
We present scaling relations between the integrated Sunyaev-Zel'dovich Effect
(SZE) signal, , its X-ray analogue, , and total mass, , for the 45 galaxy clusters in
the Bolocam X-ray-SZ (BOXSZ) sample. All parameters are integrated within
. values are measured using SZE data collected with
Bolocam, operating at 140 GHz at the Caltech Submillimeter Observatory (CSO).
The temperature, , and mass, , of the intracluster
medium are determined using X-ray data collected with Chandra, and is derived from assuming a constant gas mass fraction. Our
analysis accounts for several potential sources of bias, including: selection
effects, contamination from radio point sources, and the loss of SZE signal due
to noise filtering and beam-smoothing effects. We measure the
-- scaling to have a power-law index of , and
a fractional intrinsic scatter in of at fixed , both of which are consistent with previous analyses. We also measure the
scaling between and , finding a power-law index of
and a fractional intrinsic scatter in at fixed mass of
. While recent SZE scaling relations using X-ray mass proxies have
found power-law indices consistent with the self-similar prediction of 5/3, our
measurement stands apart by differing from the self-similar prediction by
approximately 5. Given the good agreement between the measured
-- scalings, much of this discrepancy appears to be caused
by differences in the calibration of the X-ray mass proxies adopted for each
particular analysis.Comment: 31 pages, 15 figures, accepted by ApJ 04/11/2015. This version is
appreciably different from the original submission: it includes an entirely
new appendix, extended discussion, and much of the material has been
reorganize
Pancreatic remnant fate
There is eternal discussion on the best surgical method of pancreatoduodenectomy and reconstruction method. Several different methods of pancreatic stump anastomosis exist. The most popular argument taken into account in the discussion is the frequency of early postoperative complications. Relatively fewer papers analyse the late functional outcome of pancreatic surgery and the method of anastomosis employed. Authors presented short series of 12 patients after pancreatic surgery with analysis of pancreatic remnant morphology and function. Pancreatic remnant volume, pancreatic duct distension and stool elastase-1 test were analysed. There was no correlation of pancreatic exo- or endocrine insufficiency with the volume of pancreatic remnant or the kind of surgery or anastomosis performed
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