188 research outputs found
Wandering Spleen in an Adult Man Associated With the Horseshoe Kidney
Introduction: A wandering spleen occurs when there is a laxity of the ligaments that fix the spleen in its normal anatomical position.
Case Presentation: This is a case report of a wandering spleen with horseshoe kidney in a 29-year-old male admitted with acute lower abdominal pain and vomiting to emergency department of Shariati hospital in Isfahan province. Sonographic examination showed a homogeneous 21 × 15 × 8 cm mass in the lower part of the abdomen and pelvis associated with a horseshoe kidney. Laparotomy confirmed the clinical and ultrasound findings.
Conclusions: The association of horseshoe kidney with a wandering spleen in this case may be due to an embryological anomaly
A new modified firefly algorithm for optimizing a supply chain network problem
Firefly algorithm is among the nature-inspired optimization algorithms. The standard firefly algorithm has been successfully applied to many engineering problems. However, this algorithm might be stuck in stagnation (the solutions do not enhance anymore) or possibly fall in premature convergence (fall in to the local optimum) in searching space. It seems that both issues could be connected to the exploitation and exploration. Excessive exploitation leads to premature convergence, while excessive exploration slows down the convergence. In this study, the classical firefly algorithm is modified such that make a balance between exploitation and exploration. The purposed modified algorithm ranks and sorts the initial solutions. Next, the operators named insertion, swap and reversion are utilized to search the neighbourhood of solutions in the second group, in which all these operators are chosen randomly. After that, the acquired solutions combined with the first group and the firefly algorithm finds the new potential solutions. A multi-echelon supply chain network problem is chosen to investigate the decisions associated with the distribution of multiple products that are delivered through multiple distribution centres and retailers to end customers and demonstrate the efficiency of the proposed algorithm
Characterization of the Millimeter-Wave Polarization of Centaurus A with QUaD
Centaurus (Cen) A represents one of the best candidates for an isolated,
compact, highly polarized source that is bright at typical cosmic microwave
background (CMB) experiment frequencies. We present measurements of the 4
degree by 2 degree region centered on Cen A with QUaD, a CMB polarimeter whose
absolute polarization angle is known to 0.5 degrees. Simulations are performed
to assess the effect of misestimation of the instrumental parameters on the
final measurement and systematic errors due to the field's background structure
and temporal variability from Cen A's nuclear region are determined. The total
(Q, U) of the inner lobe region is (1.00 +/- 0.07 (stat.) +/- 0.04 (sys.),
-1.72 +/- 0.06 +/- 0.05) Jy at 100 GHz and (0.80 +/- 0.06 +/- 0.06, -1.40 +/-
0.07 +/- 0.08) Jy at 150 GHz, leading to polarization angles and total errors
of -30.0 +/- 1.1 degrees and -29.1 +/- 1.7 degrees. These measurements will
allow the use of Cen A as a polarized calibration source for future millimeter
experiments.Comment: 9 pages, 8 figures, v2 matches version published in Ap
Second and third season QUaD CMB temperature and polarization power spectra
We report results from the second and third seasons of observation with the
QUaD experiment. Angular power spectra of the Cosmic Microwave Background are
derived for both temperature and polarization at both 100 GHz and 150 GHz, and
as cross frequency spectra. All spectra are subjected to an extensive set of
jackknife tests to probe for possible systematic contamination. For the
implemented data cuts and processing technique such contamination is
undetectable. We analyze the difference map formed between the 100 and 150 GHz
bands and find no evidence of foreground contamination in polarization. The
spectra are then combined to form a single set of results which are shown to be
consistent with the prevailing LCDM model. The sensitivity of the polarization
results is considerably better than that of any previous experiment -- for the
first time multiple acoustic peaks are detected in the E-mode power spectrum at
high significance.Comment: 24 pages, 23 figures, updated to reflect published versio
QUaD: A High-Resolution Cosmic Microwave Background Polarimeter
We describe the QUaD experiment, a millimeter-wavelength polarimeter designed
to observe the Cosmic Microwave Background (CMB) from a site at the South Pole.
The experiment comprises a 2.64 m Cassegrain telescope equipped with a
cryogenically cooled receiver containing an array of 62 polarization-sensitive
bolometers. The focal plane contains pixels at two different frequency bands,
100 GHz and 150 GHz, with angular resolutions of 5 arcmin and 3.5 arcmin,
respectively. The high angular resolution allows observation of CMB temperature
and polarization anisotropies over a wide range of scales. The instrument
commenced operation in early 2005 and collected science data during three
successive Austral winter seasons of observation.Comment: 23 pages, author list and text updated to reflect published versio
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The QUaD Galactic Plane Survey. II. A Compact Source Catalog
We present a catalog of compact sources derived from the QUaD Galactic Plane Survey. The survey covers ~800 deg2 of the inner galaxy (|b| < 4°) in Stokes I, Q, and U parameters at 100 and 150 GHz, with angular resolutions of 5 and 3.5 arcmin, respectively. Five hundred and twenty-six unique sources are identified in I, of which 239 are spatially matched between frequency bands, with 53 (234) detected at 100 (150) GHz alone; 170 sources are identified as ultracompact H ii regions. Approximating the distribution of total intensity source fluxes as a power law, we find a slope of γS, 100 = −1.8 ± 0.4 at 100 GHz and γS, 150 = −2.2 ± 0.4 at 150 GHz. Similarly, the power-law index of the source two-point angular correlation function is γθ, 100 = −1.21 ± 0.04 and γθ, 150 = −1.25 ± 0.04. The total intensity spectral index distribution peaks at αI ~ 0.25, indicating that dust emission is not the only source of radiation produced by these objects between 100 and 150 GHz; free–free radiation is likely significant in the 100 GHz band. Four sources are detected in polarized intensity P, of which three have matching counterparts in I. Three of the polarized sources lie close to the Galactic center, Sagittarius A*, Sagittarius B2, and the Galactic Radio Arc, while the fourth is RCW 49, a bright H ii region. An extended polarized source, undetected by the source extraction algorithm on account of its ~0fdg5 size, is identified visually, and is an isolated example of large-scale polarized emission oriented distinctly from the bulk Galactic dust polarization.Astronom
Cosmological Parameters from the QUaD CMB polarization experiment
In this paper we present a parameter estimation analysis of the polarization
and temperature power spectra from the second and third season of observations
with the QUaD experiment. QUaD has for the first time detected multiple
acoustic peaks in the E-mode polarization spectrum with high significance.
Although QUaD-only parameter constraints are not competitive with previous
results for the standard 6-parameter LCDM cosmology, they do allow meaningful
polarization-only parameter analyses for the first time. In a standard
6-parameter LCDM analysis we find the QUaD TT power spectrum to be in good
agreement with previous results. However, the QUaD polarization data shows some
tension with LCDM. The origin of this 1 to 2 sigma tension remains unclear, and
may point to new physics, residual systematics or simple random chance. We also
combine QUaD with the five-year WMAP data set and the SDSS Luminous Red
Galaxies 4th data release power spectrum, and extend our analysis to constrain
individual isocurvature mode fractions, constraining cold dark matter density,
alpha(cdmi)<0.11 (95 % CL), neutrino density, alpha(ndi)<0.26 (95 % CL), and
neutrino velocity, alpha(nvi)<0.23 (95 % CL), modes. Our analysis sets a
benchmark for future polarization experiments.Comment: 8 pages, 5 figures, submitted to Ap
Recommended from our members
Parity Violation Constraints Using Cosmic Microwave Background Polarization Spectra from 2006 and 2007 Observations by the QUaD Polarimeter
We constrain parity-violating interactions to the surface of last scattering using spectra from the QUaD experiment’s second and third seasons of observations by searching for a possible systematic rotation of the polarization directions of cosmic microwave background photons. We measure the rotation angle due to such a possible ‘‘cosmological birefringence’’ to be (random) (systematic) using QUaD’s 100 and 150 GHz temperature-curl and gradient-curl spectra over the spectra over the multipole range 200 << 2000, consistent with null, and constrain Lorentz-violating interactions to <2 10 GeV (68% confidence limit). This is the best constraint to date on electrodynamic parity violation on cosmological scales.Astronom
Parameter Estimation from Improved Measurements of the CMB from QUaD
We evaluate the contribution of cosmic microwave background (CMB)
polarization spectra to cosmological parameter constraints. We produce
cosmological parameters using high-quality CMB polarization data from the
ground-based QUaD experiment and demonstrate for the majority of parameters
that there is significant improvement on the constraints obtained from
satellite CMB polarization data. We split a multi-experiment CMB dataset into
temperature and polarization subsets and show that the best-fit confidence
regions for the LCDM 6-parameter cosmological model are consistent with each
other, and that polarization data reduces the confidence regions on all
parameters. We provide the best limits on parameters from QUaD EE/BB
polarization data and we find best-fit parameters from the multi-experiment CMB
dataset using the optimal pivot scale of k_p=0.013 Mpc-1 to be {omch2, ombh2,
H_0, A_s, n_s, tau}= {0.113, 0.0224, 70.6, 2.29 times 10^-9, 0.960, 0.086}.Comment: 7 pages, 5 figures, updated to reflect published version, minor
changes to spelling and forma
The QUAD Galactic Plane Survey 1: Maps and Analysis of Diffuse Emission
We present a survey of ~ 800 square degrees of the galactic plane observed with the QUaD telescope. The
primary product of the survey are maps of Stokes I, Q and U parameters at 100 and 150 GHz, with spatial
resolution 5 and 3.5 arcminutes respectively. Two regions are covered, spanning approximately 245 - 295°
and 315 - 5° in galactic longitude l, and -4 < b < +4° in galactic latitude b. At 0:02° square pixel size, the
median sensitivity is 74 and 107 kJy/sr at 100 GHz and 150 GHz respectively in I, and 98 and 120 kJy/sr for
Q and U. In total intensity, we find an average spectral index of α = 2:35+-0:01(stat)+-0:02(sys) for |b| ≤1°,
indicative of emission components other than thermal dust. A comparison to published dust, synchrotron
and free-free models implies an excess of emission in the 100 GHz QUaD band, while better agreement is
found at 150 GHz. A smaller excess is observed when comparing QUaD 100 GHz data to WMAP 5-year
W band; in this case the excess is likely due to the wider bandwidth of QUaD. Combining the QUaD and
WMAP data, a two-component spectral fit to the inner galactic plane (|b| ≤1°) yields mean spectral indices
of αs = -0:32+-0:03 and αd = 2:84+-0:03; the former is interpreted as a combination of the spectral indices
of synchrotron, free-free and dust, while the second is attributed largely to the thermal dust continuum. In
the same galactic latitude range, the polarization data show a high degree of alignment perpendicular to the
expected galactic magnetic field direction, and exhibit mean polarization fraction 1:38+-0:08(stat)+-0:1(sys)%
at 100 GHz and 1:70+-0:06(stat)+-0:1(sys)% at 150 GHz. We find agreement in polarization fraction between
QUaD 100 GHz and WMAP W band, the latter giving 1:1+-0:4%
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