8,516 research outputs found
Template fitting and the large-angle CMB anomalies
We investigate two possible explanations for the large-angle anomalies in the
Cosmic Microwave Background (CMB): an intrinsically anisotropic model and an
inhomogeneous model. We take as an example of the former a Bianchi model (which
leaves a spiral pattern in the sky) and of the latter a background model that
already contains a non-linear long-wavelength plane wave (leaving a stripy
pattern in the sky). We make use of an adaptation of the ``template''
formalism, previously designed to detect galactic foregrounds, to recognize
these patterns and produce confidence levels for their detection. The
``corrected'' maps, from which these patterns have been removed, are free of
anomalies, in particular their quadrupole and octupole are not planar and their
intensities not low. We stress that although the ``template'' detections are
not found to be statistically significant they do correct statistically
significant anomalies.Comment: 8 pages. MNRAS submitte
Multipole invariants and non-Gaussianity
We propose a framework for separating the information contained in the CMB
multipoles, , into its algebraically independent components. Thus
we cleanly separate information pertaining to the power spectrum,
non-Gaussianity and preferred axis effects. The formalism builds upon the
recently proposed multipole vectors (Copi, Huterer & Starkman 2003; Schwarz &
al 2004; Katz & Weeks 2004), and we elucidate a few features regarding these
vectors, namely their lack of statistical independence for a Gaussian random
process. In a few cases we explicitly relate our proposed invariants to
components of the -point correlation function (power spectrum, bispectrum).
We find the invariants' distributions using a mixture of analytical and
numerical methods. We also evaluate them for the co-added WMAP first year map
The Multipole Vectors of WMAP, and their frames and invariants
We investigate the Statistical Isotropy and Gaussianity of the CMB
fluctuations, using a set of multipole vector functions capable of separating
these two issues. In general a multipole is broken into a frame and
ordered invariants. The multipole frame is found to be suitably sensitive to
galactic cuts. We then apply our method to real WMAP datasets; a coadded masked
map, the Internal Linear Combinations map, and Wiener filtered and cleaned
maps. Taken as a whole, multipoles in the range or show
consistency with statistical isotropy, as proved by the Kolmogorov test applied
to the frame's Euler angles. This result in {\it not} inconsistent with
previous claims for a preferred direction in the sky for . The
multipole invariants also show overall consistency with Gaussianity apart from
a few anomalies of limited significance (98%), listed at the end of this paper.Comment: 9 pages. Submitted to MNRA
Discrete Symmetries of Off-Shell Electromagnetism
We discuss the discrete symmetries of the Stueckelberg-Schrodinger
relativistic quantum theory and its associated 5D local gauge theory, a
dynamical description of particle/antiparticle interactions, with monotonically
increasing Poincare-invariant parameter. In this framework, worldlines are
traced out through the parameterized evolution of spacetime events, advancing
or retreating with respect to the laboratory clock, with negative energy
trajectories appearing as antiparticles when the observer describes the
evolution using the laboratory clock. The associated gauge theory describes
local interactions between events (correlated by the invariant parameter)
mediated by five off-shell gauge fields. These gauge fields are shown to
transform tensorially under under space and time reflections, unlike the
standard Maxwell fields, and the interacting quantum theory therefore remains
manifestly Lorentz covariant. Charge conjugation symmetry in the quantum theory
is achieved by simultaneous reflection of the sense of evolution and the fifth
scalar field. Applying this procedure to the classical gauge theory leads to a
purely classical manifestation of charge conjugation, placing the CPT
symmetries on the same footing in the classical and quantum domains. In the
resulting picture, interactions do not distinguish between particle and
antiparticle trajectories -- charge conjugation merely describes the
interpretation of observed negative energy trajectories according to the
laboratory clock.Comment: 26 page
Non-Gaussianity detections in the Bianchi VIIh corrected WMAP 1-year data made with directional spherical wavelets
Many of the current anomalies reported in the Wilkinson Microwave Anisotropy
Probe (WMAP) 1-year data disappear after `correcting' for the best-fit embedded
Bianchi type VII_h component (Jaffe et al. 2005), albeit assuming no dark
energy component. We investigate the effect of this Bianchi correction on the
detections of non-Gaussianity in the WMAP data that we previously made using
directional spherical wavelets (McEwen et al. 2005a). As previously discovered
by Jaffe et al. (2005), the deviations from Gaussianity in the kurtosis of
spherical Mexican hat wavelet coefficients are eliminated once the data is
corrected for the Bianchi component. This is due to the reduction of the cold
spot at Galactic coordinates (l,b)=(209^\circ,-57\circ), which Cruz et al.
(2005) claim to be the source of non-Gaussianity introduced in the kurtosis.
Our previous detections of non-Gaussianity observed in the skewness of
spherical wavelet coefficients are not reduced by the Bianchi correction.
Indeed, the most significant detection of non-Gaussianity made with the
spherical real Morlet wavelet at a significant level of 98.4% remains (using a
very conservative method to estimate the significance). We make our code to
simulate Bianchi induced temperature fluctuations publicly available.Comment: 11 pages, 8 figures, replaced to match version accepted by MNRA
Occam's razor meets WMAP
Using a variety of quantitative implementations of Occam's razor we examine
the low quadrupole, the ``axis of evil'' effect and other detections recently
made appealing to the excellent WMAP data. We find that some razors {\it fully}
demolish the much lauded claims for departures from scale-invariance. They all
reduce to pathetic levels the evidence for a low quadrupole (or any other low
cut-off), both in the first and third year WMAP releases. The ``axis of
evil'' effect is the only anomaly examined here that survives the humiliations
of Occam's razor, and even then in the category of ``strong'' rather than
``decisive'' evidence. Statistical considerations aside, differences between
the various renditions of the datasets remain worrying
Workload control concepts in job shops: a critical assessment
The paper considers a (static) portfolio system that satisfies adding-up contraints and the gross substitution theorem. The paper shows the relationship of the two conditions to the weak dominant diagonal property of the matrix of interest rate elasticities. This enables to investigate the impact of simultaneous changes in interest rates on the asset demands.
Detection of a Dipole in the Handedness of Spiral Galaxies with Redshifts z ~ 0.04
A preference for spiral galaxies in one sector of the sky to be left-handed
or right-handed spirals would indicate a parity violating asymmetry in the
overall universe and a preferred axis. This study uses 15158 spiral galaxies
with redshifts <0.085 from the Sloan Digital Sky Survey. An unbinned analysis
for a dipole component that made no prior assumptions for the dipole axis gives
a dipole asymmetry of -0.0408\pm0.011 with a probability of occurring by chance
of 7.9 x 10-4. A similar asymmetry is seen in the Southern Galaxy spin catalog
of Iye and Sugai. The axis of the dipole asymmetry lies at approx. (l, b)
=(52{\deg}, 68.5{\deg}), roughly along that of our Galaxy and close to
alignments observed in the WMAP cosmic microwave background distributions. The
observed spin correlation extends out to separations ~210 Mpc/h, while spirals
with separations < 20 Mpc/h have smaller spin correlations.Comment: To be published in Physics Letters
Diabetic microangiopathy in Type 1 (insulin-dependent) diabetic patients after successful pancreatic and kidney or solitary kidney transplantation
To evaluate the beneficial effect of pancreatic grafting on peripheral microcirculation and long-term clinical outcome, we compared data of 28 Type 1 (insulin-dependent) diabetic patients either given a pancreatic and kidney graft simultaneously or given a solitary kidney graft (n=17). Peripheral microcirculation was estimated by transcutaneous oxygen pressure measurement (including reoxygenation potential after blood flow occlusion) and erythrocyte flow / velocity by a non-contact laser speckle method. All the measured parameters showed significant differences between diabetic and control subjects in the mean follow-up time of 49 (simultaneous pancreas and kidney transplantation) and 43 (solitary kidney transplantation) months. The data from patients after simultaneous pancreas and kidney transplantation revealed an improvement of transcutaneous oxygen pressure measurement (rise from 46±2 mm Hg to 63±3 mmHg), reoxygenation time (fall from 224±12s to 114±6s) and laser speckle measurement (rise from 4.2±1.7 to 5.6±1.8 relative units). The control group with solitary kidney transplantation did not show a positive evaluation. Data from patients after simultaneous pancreas and kidney transplantation revealed an improvement in transcutaneous oxygen pressure measurement, reoxygenation time and laser speckle measurement whereas the control group with solitary kidney transplantation did not show a positive evaluation. Improved microcirculation was more pronounced in patients with better microvascular preconditions. The results confirm that diabetic microangiopathy is positively influenced by pancreatic transplantation
The Axis of Evil revisited
In light of the three-year data release from WMAP we re-examine the evidence
for the ``Axis of Evil'' (AOE). We discover that previous statistics are not
robust with respect to the data-sets available and different treatments of the
galactic plane. We identify the cause of the instability and implement an
alternative ``model selection'' approach. A comparison to Gaussian isotropic
simulations find the features significant at the 94-98% level, depending on the
particular AOE model. The Bayesian evidence finds lower significance, ranging
from ``substantial'' at , to no evidence for the most
general AOE model.Comment: 7 pages, accepted to MNRA
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