462 research outputs found
Stringy NJL and Gross-Neveu models at finite density and temperature
Nonlocal stringy versions of the Nambu-Jona-Lasinio and Gross-Neveu models
arise in a certain limit of holographic QCD. We analyze the phase structure at
finite density and temperature at strong coupling in terms of probe branes in
the gravity dual. Comparison with the phase structure of the local field theory
models shows qualitative agreement with some aspects, and disagreement with
others. Finally, we explain how to construct the Landau potentials for these
models by taking the probe branes off-shell.Comment: 32 pages, uses JHEP3.cls; v2, references added, version to be
submitted to JHE
Chromosomes are predominantly located randomly with respect to each other in interphase human cells
To test quantitatively whether there are systematic chromosome–chromosome associations within human interphase nuclei, interchanges between all possible heterologous pairs of chromosomes were measured with 24-color whole-chromosome painting (multiplex FISH), after damage to interphase lymphocytes by sparsely ionizing radiation in vitro. An excess of interchanges for a specific chromosome pair would indicate spatial proximity between the chromosomes comprising that pair. The experimental design was such that quite small deviations from randomness (extra pairwise interchanges within a group of chromosomes) would be detectable. The only statistically significant chromosome cluster was a group of five chromosomes previously observed to be preferentially located near the center of the nucleus. However, quantitatively, the overall deviation from randomness within the whole genome was small. Thus, whereas some chromosome–chromosome associations are clearly present, at the whole-chromosomal level, the predominant overall pattern appears to be spatially random
Comparing DNA Damage-Processing Pathways by Computer Analysis of Chromosome Painting Data
Exterior, detai
Weak Lensing of the CMB: Cumulants of the Probability Distribution Function
We discuss the real-space moments of temperature anisotropies in the cosmic
microwave background (CMB) due to weak gravitational lensing by intervening
large-scale structure. We show that if the probability distribution function of
primordial temperature anisotropies is Gaussian, then it remains unchanged
after gravitational lensing. With finite resolution, however, non-zero
higher-order cumulants are generated both by lensing autocorrelations and by
cross-correlations between the lensing potential and secondary anisotropies in
the CMB such as the Sunayev-Zel'dovich (SZ) effect. Skewness is produced by
these lensing-SZ correlations, while kurtosis receives contributions from both
lensing alone and lensing-SZ correlations. We show that if the projected
lensing potential is Gaussian, all cumulants of higher-order than the kurtosis
vanish. While recent results raise the possibility of detection of the skewness
in upcoming data, the kurtosis will likely remain undetected.Comment: 11 pages, 4 figures, submitted to PR
Evaluating the RELM Test Results
We consider implications of the Regional Earthquake Likelihood Models (RELM) test results with regard to earthquake forecasting. Prospective forecasts were solicited for M≥4.95 earthquakes in California during the period 2006–2010. During this period 31 earthquakes occurred in the test region with M≥4.95. We consider five forecasts that were submitted for the test. We compare the forecasts utilizing forecast verification methodology developed in the atmospheric sciences, specifically for tornadoes. We utilize a “skill score” based on the forecast scores λfi of occurrence of the test earthquakes. A perfect forecast would have λfi=1, and a random (no skill) forecast would have λfi=2.86×10-3. The best forecasts (largest value of λfi) for the 31 earthquakes had values of λfi=1.24×10-1 to λfi=5.49×10-3. The best mean forecast for all earthquakes was λ̅f=2.84×10-2. The best forecasts are about an order of magnitude better than random forecasts. We discuss the earthquakes, the forecasts, and alternative methods of evaluation of the performance of RELM forecasts. We also discuss the relative merits of alarm-based versus probability-based forecasts
Density growth in Kantowski-Sachs cosmologies with cosmological constant
In this work the growth of density perturbations in Kantowski-Sachs
cosmologies with a positive cosmological constant is studied, using the 1+3 and
1+1+2 covariant formalisms. For each wave number we obtain a closed system for
scalars formed from quantities that are zero on the background and hence are
gauge-invariant. The solutions to this system are then analyzed both
analytically and numerically. In particular the effects of anisotropy and the
behaviour close to a bounce in the cosmic scale factor are considered. We find
that typically the density gradient in the bouncing directions experiences a
local maximum at or slightly after the bounce.Comment: 33 pages, 17 picture
Exchange Rates and Trade Balance Adjustment: A Multi-Country Empirical Analysis
This study assesses the response of the trade balance to exchange rate fluctuations across a large number of countries. Fixed-effects regressions are estimated for three country groups (industrial, developing and emerging markets) on annual data for 87 countries from 1994 to 2010. The trade balance improves significantly after a real depreciation, and to a similar degree, in the long run for all countries, but the adjustment is significantly slower for industrial countries. Emerging markets and developing countries display relatively fast adjustment. Disaggregation into exports and imports shows that the delayed adjustment in industrial countries is almost entirely on the export side. The rate of adjustment in emerging markets is slowing over time, consistent with their eventual graduation to high-income status. The ratio of trade to GDP is also highly sensitive to the real effective exchange rate, with a real depreciation of 10 % raising the trade/GDP ratio across the sample by approximately 4 %. This result, which presumably reflects movements in the prices of tradables relative to non-tradables, raises questions about the widespread use of the trade/GDP ratio as a trade policy indicator, without adjustment for real exchange rate effects
Cross-Correlation of the Cosmic Microwave Background with the 2MASS Galaxy Survey: Signatures of Dark Energy, Hot Gas, and Point Sources
We cross-correlate the Cosmic Microwave Background (CMB) temperature
anisotropies observed by the Wilkinson Microwave Anisotropy Probe (WMAP) with
the projected distribution of extended sources in the Two Micron All Sky Survey
(2MASS). By modelling the theoretical expectation for this signal, we extract
the signatures of dark energy (Integrated Sachs-Wolfe effect;ISW), hot gas
(thermal Sunyaev-Zeldovich effect;thermal SZ), and microwave point sources in
the cross-correlation. Our strongest signal is the thermal SZ, at the 3.1-3.7
\sigma level, which is consistent with the theoretical prediction based on
observations of X-ray clusters. We also see the ISW signal at the 2.5 \sigma
level, which is consistent with the expected value for the concordance LCDM
cosmology, and is an independent signature of the presence of dark energy in
the universe. Finally, we see the signature of microwave point sources at the
2.7 \sigma level.Comment: 35 pages (preprint format), 8 figures. In addition to minor revisions
based on referee's comments, after correcting for a bug in the code, the SZ
detection is consistent with the X-ray observations. Accepeted for
publication in Physical Review
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