8,471 research outputs found
Heat and Mass Transfer in Cold Regions Soils
The work upon which this report is based was made possible by a cooperative
aid agreement between the U.S. Forest Service, Institute of Northern
Forestry, Fairbanks, Alaska, and the Institute of Water Resources, University
of Alaska. Contributions to this study were also made by the University of
California at Davis and Ohio State University. The collection of winter
data on pore pressures was made possible by a separate grant by the Office
of Water Research and Technology (project A-053 ALAS)
A giant planet beyond the snow line in microlensing event OGLE-2011-BLG-0251
Aims. We present the analysis of the gravitational microlensing event OGLE-2011-BLG-0251. This anomalous event was observed by several survey and follow-up collaborations conducting microlensing observations towards the Galactic bulge.
Methods. Based on detailed modelling of the observed light curve, we find that the lens is composed of two masses with a mass ratio q = 1.9 × 10^(-3). Thanks to our detection of higher-order effects on the light curve due to the Earth’s orbital motion and the finite size of source, we are able to measure the mass and distance to the lens unambiguously.
Results. We find that the lens is made up of a planet of mass 0.53 ± 0.21 M_J orbiting an M dwarf host star with a mass of 0.26 ± 0.11 M_⊙. The planetary system is located at a distance of 2.57 ± 0.61 kpc towards the Galactic centre. The projected separation of the planet from its host star is d = 1.408 ± 0.019, in units of the Einstein radius, which corresponds to 2.72 ± 0.75 AU in physical units. We also identified a competitive model with similar planet and host star masses, but with a smaller orbital radius of 1.50 ± 0.50 AU. The planet is therefore located beyond the snow line of its host star, which we estimate to be around ~1−1.5 AU
Quantum Hall line junction with impurities as a multi-slit Luttinger liquid interferometer
We report on quantum interference between a pair of counterpropagating
quantum Hall edge states that are separated by a high quality tunnel barrier.
Observed Aharonov-Bohm oscillations are analyzed in terms of resonant tunneling
between coupled Luttinger liquids that creates bound electronic states between
pairs of tunnel centers that act like interference slits. We place a lower
bound in the range of 20-40 m for the phase coherence length and directly
confirm the extended phase coherence of quantum Hall edge states.Comment: 4 pages, 3 figures, 1 tabl
Quantum and Classical Binomial Distributions for the Charge Transmitted through Coherent Conductor
We discuss controversial results for the statistics of charge transport
through coherent conductors. Two distribution functions for the charge
transmitted was obtained previously, first by L.Levitov and G.Lesovik, [JETP
Letters Vol.55 p.555 (1992)] and the other initially by the same authors [ibid.
Vol.58 p.230 (1993)], and later the result was reproduced by several authors.
The latter distribution functions actually coincides with classical binomial
distribution (though obtained purely quantum mechanically) former (result of
1992) is different and we call it here quantum binomial distribution. The two
distribution function represent two opposite universal limits - one is purely
quantum, where interference is important, and the other is semiclassical, where
interference is smeared out. We show, that high order charge correlators,
determined by the either distribution functions, can all be measured in
different setups. The high order current correlators, starting the third order,
reveal (missed in previous studies) special oscillating frequency dependence on
the scale of the inverted time flight from the obstacle to the measuring point.
Depending on setup, the oscillating terms give substantially different
contributions.Comment: 4 pages; english versio
Spin- and charge-density oscillations in spin chains and quantum wires
We analyze the spin- and charge-density oscillations near impurities in spin
chains and quantum wires. These so-called Friedel oscillations give detailed
information about the impurity and also about the interactions in the system.
The temperature dependence of these oscillations explicitly shows the
renormalization of backscattering and conductivity, which we analyze for a
number of different impurity models. We are also able to analyze screening
effects in one dimension. The relation to the Kondo effect and experimental
consequences are discussed.Comment: Final published version. 15 pages in revtex format including 22
epsf-embedded figures. The latest version in PDF format is available from
http://fy.chalmers.se/~eggert/papers/density-osc.pd
Inflation without Inflaton(s)
We propose a model for early universe cosmology without the need for
fundamental scalar fields. Cosmic acceleration and phenomenologically viable
reheating of the universe results from a series of energy transitions, where
during each transition vacuum energy is converted to thermal radiation. We show
that this `cascading universe' can lead to successful generation of adiabatic
density fluctuations and an observable gravity wave spectrum in some cases,
where in the simplest case it reproduces a spectrum similar to slow-roll models
of inflation. We also find the model provides a reasonable reheating
temperature after inflation ends. This type of model may also be relevant for
addressing the smallness of the vacuum energy today.Comment: 13 pages, 4 figures, published versio
W-band 0.3W PHEMT MMIC power amplifier module
A compact (1.8 by 3.0 by 3.8 cm) WR-10 waveguide amplifier module providing 310-mW power output, 20-dB gain, and 5 GHz of 1-dB bandwidth at a center frequency of 96 GHz is described. The module is comprised of 22 identical PHEMT chips, 4-way microstrip power combiners and dividers, and a 4-way waveguide power combiner
The LeFE Algorithm: Embracing the Complexity of Gene Expression in the Interpretation of Microarray Data
The LeFE algorithm has been developed to address the complex, non-linear regulation of gene expression. Interpretation of microarray data remains a challenge, and most methods fail to consider the complex, nonlinear regulation of gene expression. To address that limitation, we introduce Learner of Functional Enrichment (LeFE), a statistical/machine learning algorithm based on Random Forest, and demonstrate it on several diverse datasets: smoker/never smoker, breast cancer classification, and cancer drug sensitivity. We also compare it with previously published algorithms, including Gene Set Enrichment Analysis. LeFE regularly identifies statistically significant functional themes consistent with known biology.National Cancer Institute's Center for Cancer Researc
- …