699 research outputs found
Analysis of Transit Fare Evasion in the Rose Quarter
Tri-Met collected fare evasion data for buses and MAX trains passing outbound through the Rose Quarter Monday, June 11 through Saturday, July 7. Beginning September 2001, Tri-Met’s “Fareless Square’s” free zone was extended towards the Lloyd District, with an eastern boundary of NE 14th. Prior to this, all trips between the Central Business District and Lloyd Center required a full Zone 1 fare
Using Big Bang Nucleosynthesis to Extend CMB Probes of Neutrino Physics
We present calculations showing that upcoming Cosmic Microwave Background
(CMB) experiments will have the power to improve on current constraints on
neutrino masses and provide new limits on neutrino degeneracy parameters. The
latter could surpass those derived from Big Bang Nucleosynthesis (BBN) and the
observationally-inferred primordial helium abundance. These conclusions derive
from our Monte Carlo Markov Chain (MCMC) simulations which incorporate a full
BBN nuclear reaction network. This provides a self-consistent treatment of the
helium abundance, the baryon number, the three individual neutrino degeneracy
parameters and other cosmological parameters. Our analysis focuses on the
effects of gravitational lensing on CMB constraints on neutrino rest mass and
degeneracy parameter. We find for the PLANCK experiment that total (summed)
neutrino mass eV could be ruled out at or better.
Likewise neutrino degeneracy parameters and could be detected or ruled out at
confidence, or better. For POLARBEAR we find that the corresponding detectable
values are , , and , while for EPIC we obtain ,
, and . Our forcast for
EPIC demonstrates that CMB observations have the potential to set constraints
on neutrino degeneracy parameters which are better than BBN-derived limits and
an order of magnitude better than current WMAP-derived limits.Comment: 27 pages, 11 figures, matches published version in JCA
CMB Beam Systematics: Impact on Lensing Parameter Estimation
The CMB's B-mode polarization provides a handle on several cosmological
parameters most notably the tensor-to-scalar ratio, , and is sensitive to
parameters which govern the growth of large scale structure (LSS) and evolution
of the gravitational potential. The primordial gravitational-wave- and
secondary lensing-induced B-mode signals are very weak and therefore prone to
various foregrounds and systematics. In this work we use Fisher-matrix-based
estimations and apply, for the first time, Monte-Carlo Markov Chain (MCMC)
simulations to determine the effect of beam systematics on the inferred
cosmological parameters from five upcoming experiments: PLANCK, POLARBEAR,
SPIDER, QUIET+CLOVER and CMBPOL. We consider beam systematics which couple the
beam substructure to the gradient of temperature anisotropy and polarization
(differential beamwidth, pointing and ellipticity) and beam systematics due to
differential beam normalization (differential gain) and orientation (beam
rotation) of the polarization-sensitive axes (the latter two effects are
insensitive to the beam substructure). We determine allowable levels of beam
systematics for given tolerances on the induced parameter errors and check for
possible biases in the inferred parameters concomitant with potential increases
in the statistical uncertainty. All our results are scaled to the 'worst case
scenario'. In this case and for our tolerance levels, the beam rotation should
not exceed the few-degree to sub-degree level, typical ellipticity is required
to be 1% level, the differential gain allowed level is a few parts in
to , differential beamwidth upper limits are of the sub-percent level
and differential pointing should not exceed the few- to sub-arcsec level.Comment: 19 pages, 4 figures, 13 tables. Version matches published versio
CMB Polarization Systematics Due to Beam Asymmetry: Impact on Cosmological Birefringence
The standard cosmological model is assumed to respect parity symmetry. Under
this assumption the cross-correlations of the CMB's temperature anisotropy and
`gradient'-like polarization, with the `curl'-like polarization identically
vanish over the full sky. However, extensions of the standard model which allow
for light scalar field or axion coupling to the electromagnetic field, or
coupling to the Riemann gravitational field-strength, as well as other
modifications of field theories, may induce a rotation of the CMB polarization
plane on cosmological scales and manifest itself as nonvanishing TB and EB
cross-correlations. Recently, the degree of parity violation (reflected in
polarization rotation) was constrained using data from BOOMERANG, WMAP and
QUAD. Forecasts have been made for near-future experiments (e.g. PLANCK) to
further constrain parity- and Lorentz-violating terms in the fundamental
interactions of nature. Here we consider a real-world effect induced by a class
of telescope beam systematics which can mimic the rotation of polarization
plane or otherwise induce nonvanishing TB and EB correlations. In particular,
adopting the viewpoint that the primary target of future experiments will be
the inflationary B-mode signal, we assume the beam-systematics of the upcoming
PLANCK and POLARBEAR experiments are optimized towards this goal, and explore
the implications of the allowed levels of beam systematics on the resulting
precision of polarization-rotation measurements.Comment: 9 pages. Minor typos corrected. Matches published version in PRD Vol.
79 No. 1
The Effects of Game Size on the Physical Activity Levels and Ball Touches of Elementary School Children in Physical Education
The purpose of this study was to determine the impact of participating in small (3v3), medium (6v6), and large-sided (12v12) games on the physical activity levels (pedometer step counts, accelerometer counts, and minutes of moderate-to-vigorous physical activity) and ball touches of children in physical education class. Participants were 29 students (55% boys and 45% girls) age 10-11 yrs. All participants wore a Yamax SW-200 pedometer and had their ball touches monitored and recorded. Twelve participants also wore an ActiGraph GT3X accelerometer. Repeated measure ANOVAs were computed to test for significant differences for each dependant variable with corresponding post hoc tests. Results indicated the 3v3 and 6v6 game conditions yielded significantly higher accelerometer counts and ball touches than the 12v12 condition. The 3v3 game condition also produced significantly higher ball touches than the 6v6 condition. These findings highlight the importance of utilizing smaller-sided games in physical education to promote increased involvement and physical activity
Revealing Cosmic Rotation
Cosmological Birefringence (CB), a rotation of the polarization plane of
radiation coming to us from distant astrophysical sources, may reveal parity
violation in either the electromagnetic or gravitational sectors of the
fundamental interactions in nature. Until only recently this phenomenon could
be probed with only radio observations or observations at UV wavelengths.
Recently, there is a substantial effort to constrain such non-standard models
using observations of the rotation of the polarization plane of cosmic
microwave background (CMB) radiation. This can be done via measurements of the
-modes of the CMB or by measuring its TB and EB correlations which vanish in
the standard model. In this paper we show that correlations-based
estimator is the best for upcoming polarization experiments. The based
estimator surpasses other estimators because it has the smallest noise and of
all the estimators is least affected by systematics. Current polarimeters are
optimized for the detection of -mode polarization from either primordial
gravitational waves or by large scale structure via gravitational lensing. In
the paper we also study optimization of CMB experiments for the detection of
cosmological birefringence, in the presence of instrumental systematics, which
by themselves are capable of producing correlations; potentially mimicking
CB.Comment: 10 pages, 3 figures, 2 table
CMB Temperature Polarization Correlation and Primordial Gravitational Waves
We examine the use of the CMB's TE cross correlation power spectrum as a
complementary test to detect primordial gravitational waves (PGWs). The first
method used is based on the determination of the lowest multipole, ,
where the TE power spectrum, , first changes sign. The second
method uses Wiener filtering on the CMB TE data to remove the density
perturbations contribution to the TE power spectrum. In principle this leaves
only the contribution of PGWs. We examine two toy experiments (one ideal and
another more realistic) to see their ability to constrain PGWs using the TE
power spectrum alone. We found that an ideal experiment, one limited only by
cosmic variance, can detect PGWs with a ratio of tensor to scalar metric
perturbation power spectra at 99.9% confidence level using only the TE
correlation. This value is comparable with current constraints obtained by WMAP
based on the upper limits to the B-mode amplitude. We demonstrate
that to measure PGWs by their contribution to the TE cross correlation power
spectrum in a realistic ground based experiment when real instrumental noise is
taken into account, the tensor-to-scalar ratio, , should be approximately
three times larger.Comment: 13 pages, 13 figures, version matches published version. Combined
with 0710.365
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