788 research outputs found
Duality and other Exotic Gauge Dynamics in Softly Broken Supersymmetric QCD
We analyze the theory of softly broken supersymmetric . Exotic behavior
like spontaneously broken baryon number, massless composite fermions and
Seiberg's duality seems to persist also in the presence of (small) soft
supersymmetry breaking. We argue that certain, specially tailored, lattice
simulations may be able to detect the novel phenomena. Most of the exotic
behavior does not survive the decoupling limit of large SUSY breaking
parameters.Comment: 13 page
Ex Post Facto Evaluation of Neighborhood Organization Programs
Quasi-experimental designs, which are currently dominant in the methodological literature on Evaluative Research, are mostly not appropriate for the evaluation of Planned Change in the social organization of urban neighborhoods. In this paper we propose an alternative approach, based on ex-post-facto case studies. Criteria for evaluation, as well as study design and instruments, are discussed in some detail. A concise summary of one local evaluative study is presented as an illustration
(T) Duality and other Exotic Gauge Dynamics in Softly Broken Supersymmetric QCD
We analyze the theory of softly broken supersymmetric QCD. Exotic behavior like spontaneously broken baryon number, massless composite fermions and Seiberg’s duality seems to persist also in the presence of (small) soft supersymmetry breaking. We argue that certain, specially tailored, lattice simulations may be able to detect the novel phenomena. Most of the exotic behavior does not survive the decoupling limit of large SUSY breaking parameters. Based on a talk presented by J. S in SUSY 95
Cosmic Microwave Background Temperature at Galaxy Clusters
We have deduced the cosmic microwave background (CMB) temperature in the Coma
cluster (A1656, ), and in A2163 () from spectral
measurements of the Sunyaev-Zel'dovich (SZ) effect over four passbands at radio
and microwave frequencies. The resulting temperatures at these redshifts are
K and K, respectively. These values confirm the expected
relation , where K is the value
measured by the COBE/FIRAS experiment. Alternative scaling relations that are
conjectured in non-standard cosmologies can be constrained by the data; for
example, if or , then
and (at 95% confidence). We
briefly discuss future prospects for more precise SZ measurements of at
higher redshifts.Comment: 13 pages, 1 figure, ApJL accepted for publicatio
Coherent optical control of correlation waves of spins in semiconductors
We calculate the dynamical fluctuation spectrum of electronic spins in a
semiconductor under a steady-state illumination by light containing
polarization squeezing correlations. Taking into account quasi-particle
lifetime and spin relaxation for this non-equilibrium situation we consider up
to fourth order optical effects which are sensitive to the squeezing phases.
We demonstrate the possibility to control the spin fluctuations by optically
modulating these phases as a function of frequency, leading to a non-Lorentzian
spectrum which is very different from the thermal equilibrium fluctuations in
n-doped semiconductors. Specifically, in the time-domain spin-spin correlation
can exhibit time delays and sign flips originating from the phase modulations
and correlations of polarizations, respectively. For higher light intensity we
expect a regime where the squeezing correlations will dominate the spectrum.Comment: 17 pages, 8 figure
Estimating mangrove canopy height and above-ground biomass in the Everglades National Park with airborne LiDAR and TanDEM-X data
Mangrove forests are important natural ecosystems due to their ability to capture and store large amounts of carbon. Forest structural parameters, such as canopy height and above-ground biomass (AGB), provide a good measure for monitoring temporal changes in carbon content. The protected coastal mangrove forest of the Everglades National Park (ENP) provides an ideal location for studying these processes, as harmful human activities are minimal. We estimated mangrove canopy height and AGB in the ENP using Airborne LiDAR/Laser (ALS) and TanDEM-X (TDX) datasets acquired between 2011 and 2013. Analysis of both datasets revealed that mangrove canopy height can reach up to ~25 m and AGB can reach up to ~250 Mg·ha-1. In general, mangroves ranging from 9 m to 12 m in stature dominate the forest canopy. The comparison of ALS and TDX canopy height observations yielded an R2 = 0.85 and Root Mean Square Error (RMSE) = 1.96 m. Compared to a previous study based on data acquired during 2000-2004, our analysis shows an increase in mangrove stature and AGB, suggesting that ENP mangrove forests are continuing to accumulate biomass. Our results suggest that ENP mangrove forests have managed to recover from natural disturbances, such as HurricaneWilma
Triple Experiment Spectrum of the Sunyaev-Zeldovich Effect in the Coma Cluster: H_0
The Sunyaev-Zeldovich (SZ) effect was previously measured in the Coma cluster
by the Owens Valley Radio Observatory and Millimeter and IR Testa Grigia
Observatory experiments and recently also with the Wilkinson Microwave
Anisotropy Probe satellite. We assess the consistency of these results and
their implications on the feasibility of high-frequency SZ work with
ground-based telescopes. The unique data set from the combined measurements at
six frequency bands is jointly analyzed, resulting in a best-fit value for the
Thomson optical depth at the cluster center, tau_{0}=(5.35 \pm 0.67) 10^{-3}.
The combined X-ray and SZ determined properties of the gas are used to
determine the Hubble constant. For isothermal gas with a \beta density profile
we derive H_0 = 84 \pm 26 km/(s\cdot Mpc); the (1\sigma) error includes only
observational SZ and X-ray uncertainties.Comment: 11 pages, 1 figur
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
A multiscale approach for detection and mapping differential subsidence using multi-platform InSAR products
Detecting and mapping subsidence is currently supported by interferometric synthetic aperture radar (InSAR) products. However, several factors, such as band-dependent processing, noise presence, and strong subsidence limit the use of InSAR for assessing differential subsidence, which can lead to ground instability and damage to infrastructure. In this work, we propose an approach for measuring and mapping differential subsidence using InSAR products. We consider synthetic aperture radar (SAR) data availability, data coverage over time and space, and the region\u27s subsidence rates to evaluate the need of post-processing, and only then we interpret the results. We illustrate our approach with two case-examples in Central Mexico, where we process SAR data from the Japanese ALOS (L-band), the German TerraSAR-X (X-band), the Italian COSMO-SkyMed (X-band) and the European Sentinel-1 (C-band) satellites. We find good agreement between our results on differential subsidence and field data of existing faulting and find potential to map yet-to-develop faults
On the Sensitivity of Deflagrations in Chandrasekhar Mass White Dwarf to Initial Conditions
We analyze the sensitivity of the flame propagation in a Chandrasekhar mass
white dwarf to initial conditions during the subsonic burning phase, using 2D
simulations of the full WD. Results are presented for a wide variety of initial
flame distributions including central and off-center single point and
multi-point, simultaneous and non-simultaneous, ignitions. We also examine the
effects of convective velocity field which should exist at the core before the
thermo-nuclear runaway. Our main conclusion suggests that the amounts of
burning products and their distributions through the deflagration phase are
extremely sensitive to initial conditions, much more sensitive than presented
in previous studies. In particular, we find that more complex configurations
such as even slight off-center ignitions, non-simultaneous multi-point
ignitions and velocity fields tend to favor solutions in which individual
plumes rise faster than the bulk of a typical Rayleigh-Taylor driven, unstable
burning front. The difference to previous calculations for an octant of a WD
may be understood as a consequence of the suppression of l=1,2 modes. Our
results are consistent with full star calculations by the Chicago group.
Moreover, the total amount of nuclear burning during the phase of subsonic
burning depends sensitively on the initial conditions and may cause the WD to
pulsate or to become unbound. We discuss the implications of the results on
current models for Type Ia SNe, limitations imposed by the 2-D nature of our
study, and suggest directions for further study.Comment: 13 pages, 5 figures, ApJ submitte
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