4,067 research outputs found
Characterization of slow and fast phase nystagmus
A current literature review of the analog and digital process of vestibular and optical kinetic nystagmus reveals little agreement in the methods used by various labs. The strategies for detection of saccade (fast phase velocity component of nystagmus) vary between labs, and most of the process have not been evaluated and validated with a standard database. A survey was made of major vestibular labs in the U.S. that perform computer analyses of vestibular and optokinetic reflexes to stimuli, and a baseline was established from which to standardize data acquisition and analysis programs. The concept of an Error Index was employed as the criterium for evaluating the performance of the vestibular analysis software programs. The performance criterium is based on the detection of saccades and is the average of the percentages of missed detections and false detections. Evaluation of the programs produced results for lateral gaze with saccadic amplitude of one, two, three, five, and ten degrees with various signal-to-noise ratios. In addition, results were obtained for sinusoidal pursuit of 0.05, 0.10, and 0.50 Hz with saccades from one to ten degrees at various signal-to-noise ratios. Selection of the best program was made from the performance in the lateral gaze with three degrees of saccadic amplitude and in the 0.10 Hz sinusoid with three degrees of saccadic amplitude
CP-violating asymmetries in top-quark production and decay in annihilation within the MSSM
We obtain analytic formulae for the cross section of the sequential processes
of and in the laboratory frame where the
dependence on triple product correlations of the type (\hat(q}_1 x \hat{q}_2 .
\hat{q}_3), induced by CP violation both in the production and the decay are
explicitely shown. Different observables sensitive to CP violation are defined
and calculated in the Minimal Supersymmetric Standard Model (MSSM). The
observables sensitive to CP violation are of the order of . The
dependence on the masses of the supersymmetric particles is also shown.Comment: 17 pages of LateX plus five uuencoded Postscript figures, LateX file
and PS-figures are also available via anonymous ftp at
ftp://info.oeaw.ac.at/pub/hephy-pub/62
Reddening and Distance of the Local Group Starburst Galaxy IC 10
We estimate the reddening and distance of the nearest starburst galaxy IC 10
using deep near infrared photometry obtained with the Multi-Object
InfraRed Camera and Spectrograph (MOIRCS) on the Subaru telescope. We estimate
the foreground reddening toward IC 10 using photometry of IC 10 from the
Local Group Survey, obtaining mag. We derive the total
reddening including the internal reddening, mag, using
photometry of early-type stars in IC 10 and comparing
photometry of red giant branch stars in IC 10 and the SMC. Using the 2MASS
point source catalog of 20 Galactic globular clusters, we derive a relation
between the metallicity [Fe/H] and the slope of the red giant branch
in the color-magnitude diagram. The mean metallicity of the
red giant branch stars in IC 10 is estimated to be
[Fe/H]. The magnitude of the tip of the red giant branch
(TRGB) of IC 10 in the band is measured to be
. Based on the TRGB method, we estimate the distance
modulus of IC 10 to be , corresponding to the distance of kpc. This
confirms that IC 10 is a member of the Local Group.Comment: 35 pages, 11 figures, To appear in the Astrophysical Journal, 200
Testing for rational bubbles in the presence of structural breaks: Evidence from nonstationary panels
This is the post-print version of the final paper published in Journal of Banking & Finance. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2011 Elsevier B.V.This paper presents new results on the rational bubbles hypothesis for a panel of 18 OECD countries using the model developed by Campbell (2000). We provide an analysis of international data that exploits increased power deriving from the panel unit root and cointegration methodology, together with the flexibility of allowing explicitly for multiple endogenous structural breaks in the individual series. Differently from the time series methodology, the panel data approach allows for a global analysis of the financial crashes that are related to rational bubbles. We find strong evidence in favor of bubbles phenomena
Ab-initio study of the stability and electronic properties of wurtzite and zinc-blende BeS nanowires
In this work we study the structural stability and electronic properties of
the Beryllium sulphide nanowires (NWs) in both zinc blende (ZB) and wurtzite
(WZ) phases with triangle and hexagonal cross section, using first principle
calculations within plane-wave pseudopotential method. A phenomenological model
is used to explain the role of dangling bonds in the stability of the NWs. In
contrast to the bulk phase, ZB-NWs with diameter less than 133.3 (angstrom) are
found to be less favorable over WZ-NWs, in which the surface dangling bonds
(DBs) on the NW facets play an important role to stabilize the NWs.
Furthermore, both ZB and WZ NWs are predicted to be semiconductor and the
values of the band gaps are dependent on the surface DBs as well as the size
and shape of NWs. Finally, we performed atom projected density-of states
(PDOSs) analysis by calculating the localized density of states on the surface
atoms, as well as on the core and edge atoms.Comment: 9 Pages, 6 Figure
Could Large CP Violation Be Detected at Colliders?
We argue that CP--violation effects below a few tenths of a percent are
probably undetectable at hadron and electron colliders. Thus only operators
whose contributions interfere with tree--level Standard Model amplitudes are
detectable. We list these operators for Standard Model external particles and
some two and three body final state reactions that could show detectable
effects. These could test electroweak baryogenesis scenarios.Comment: 11pp, LaTeX, UM--TH--92--27(massaged to make TeX output cleaner), no
picture
CHANG-ES XI: Circular Polarization in the Cores of Nearby Galaxies
We detect 5 galaxies in the CHANG-ES (Continuum Halos in Nearby Galaxies --
an EVLA Survey) sample that show circular polarization (CP) at L-band in our
high resolution data sets. Two of the galaxies (NGC~4388 and NGC~4845) show
strong Stokes \%, two (NGC~660 and NGC~3628) have
values of \%, and NGC~3079 is a marginal detection at \%. The two strongest galaxies also have the most luminous X-ray
cores and the strongest internal absorption in X-rays. We have expanded on our
previous Faraday conversion interpretation and analysis and provide analytical
expressions for the expected signal for a general case in which the cosmic
ray electron energy spectral index can take on any value. We provide examples
as to how such expressions could be used to estimate magnetic field strengths
and the lower energy cutoff for CR electrons. Four out of our detections are
{\it resolved}, showing unique structures, including a {\it jet} in NGC~4388
and a CP `conversion disk' in NGC~4845. The conversion disk is inclined to the
galactic disk but is perpendicular to a possible outflow direction. Such CP
structures have never before been seen in any galaxy to our knowledge. None of
the galaxy cores show linear polarization at L-band. Thus CP may provide a
unique probe of physical conditions deep into radio AGNs.Comment: 30 pages, 4 figures, accepted to MNRA
Electronic measurement and control of spin transport in Silicon
The electron spin lifetime and diffusion length are transport parameters that
define the scale of coherence in spintronic devices and circuits. Since these
parameters are many orders of magnitude larger in semiconductors than in
metals, semiconductors could be the most suitable for spintronics. Thus far,
spin transport has only been measured in direct-bandgap semiconductors or in
combination with magnetic semiconductors, excluding a wide range of
non-magnetic semiconductors with indirect bandgaps. Most notable in this group
is silicon (Si), which (in addition to its market entrenchment in electronics)
has long been predicted a superior semiconductor for spintronics with enhanced
lifetime and diffusion length due to low spin-orbit scattering and lattice
inversion symmetry. Despite its exciting promise, a demonstration of coherent
spin transport in Si has remained elusive, because most experiments focused on
magnetoresistive devices; these methods fail because of universal impedance
mismatch obstacles, and are obscured by Lorentz magnetoresistance and Hall
effects. Here we demonstrate conduction band spin transport across 10 microns
undoped Si, by using spin-dependent ballistic hot-electron filtering through
ferromagnetic thin films for both spin-injection and detection. Not based on
magnetoresistance, the hot electron spin-injection and detection avoids
impedance mismatch issues and prevents interference from parasitic effects. The
clean collector current thus shows independent magnetic and electrical control
of spin precession and confirms spin coherent drift in the conduction band of
silicon.Comment: Single PDF file with 4 Figure
A Probe of New Physics in Top Quark Pair Production at Colliders
We describe how to probe new physics through examination of the form factors
describing the Ztt couplings via the scattering process e^-e^+->t+tbar. We
focus on experimental methods on how the top quark momentum can be determined
and show how this can be applied to select polarized samples of
pairs through the angular correlations in the final state leptons. We also
study the dependence on the energy and luminosity of an \ee\ collider to probe
a CP violating asymmetry at the level.}Comment: 24 pages in TeXsis (figures available upon request) (revised July
1993
An accurate test for homogeneity of odds ratios based on Cochran's Q-statistic
Background: A frequently used statistic for testing homogeneity in a meta-analysis of K independent studies is Cochran's Q. For a standard test of homogeneity the Q statistic is referred to a chi-square distribution with K - 1 degrees of freedom. For the situation in which the effects of the studies are logarithms of odds ratios, the chi-square distribution is much too conservative for moderate size studies, although it may be asymptotically correct as the individual studies become large. Methods: Using a mixture of theoretical results and simulations, we provide formulas to estimate the shape and scale parameters of a gamma distribution to t the distribution of Q. Results: Simulation studies show that the gamma distribution is a good approximation to the distribution for Q. Conclusions: : Use of the gamma distribution instead of the chi-square distribution for Q should eliminate inaccurate inferences in assessing homogeneity in a meta-analysis. (A computer program for implementing this test is provided.) This hypothesis test is competitive with the Breslow-Day test both in accuracy of level and in power
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