9,019 research outputs found
Thermopower of gapped bilayer graphene
We calculate thermopower of clean and impure bilayer graphene systems.
Opening a band gap through the application of an external electric field is
shown to greatly enhance the thermopower of bilayer graphene, which is more
than four times that of the monolayer graphene and gapless bilayer graphene at
room temperature. The effect of scattering by dilute charged impurities is
discussed in terms of the self-consistent Born approximation. Temperature
dependence of the thermopower is also analyzed.Comment: 8 pages, 5 figures; An inconsistency in the definitions of Eq.(17)
and (18) in version 1 is found and correcte
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Evaluating the Relationship Between the Carbon and Sulfur Cycles in the Later Cambrian Ocean: An Example from the Port au Port Group, Western Newfoundland, Canada
We present a high-resolution δ34S (sulfate and pyrite) and δ13Ccarbonate record from the Middle–Upper Cambrian Port au Port Group, a mixed carbonate-siliciclastic succession exposed in western Newfoundland, Canada. The results illustrate systematic δ34Ssulfate shifts of > 15‰ over relatively short stratigraphic intervals (10 m, likely 15‰ δ34Ssulfate shifts recognized in Port au Port strata. Such large shifts can be generated only if fluctuating oceanic redox is invoked; marine anoxia forces reduced C/S burial and elevated Δ34S, driving larger δ34S changes per mole of organic carbon buried. The conclusion that later Cambrian oceans featured both low sulfate levels and widespread subsurface anoxia supports hypotheses that link fluctuating marine redox conditions in the delayed recovery of skeletal animals and metazoan reefs from late Early Cambrian extinction.Organismic and Evolutionary Biolog
Dynamical phase transition for a quantum particle source
We analyze the time evolution describing a quantum source for noninteracting
particles, either bosons or fermions. The growth behaviour of the particle
number (trace of the density matrix) is investigated, leading to spectral
criteria for sublinear or linear growth in the fermionic case, but also
establishing the possibility of exponential growth for bosons. We further study
the local convergence of the density matrix in the long time limit and prove
the semiclassical limit.Comment: 24 pages; In the new version, we added several references concerning
open quantum systems and present an extended result on linear particle
production in the fermionic cas
Update in Antiepidermal Growth Factor Receptor Therapy in the Management of Metastatic Colorectal Cancer
The approval of anti-epidermal growth factor receptor (EGFR) monoclonal antibodies in the treatment of metastatic colorectal cancer (CRC) has expanded the armamentarium against this disease.
This paper will review the historical progress and recent clinical developments of anti-EGFR therapies in the treatment of metastatic CRC. Novel strategies of targeting the EGFR pathway to improve efficacy as well as ongoing research in identifying specific molecular predictors of response will be discussed
Mid-Infrared Ethane Emission on Neptune and Uranus
We report 8- to 13-micron spectral observations of Neptune and Uranus from
the NASA Infrared Telescope Facility spanning more than a decade. The
spectroscopic data indicate a steady increase in Neptune's mean atmospheric
12-micron ethane emission from 1985 to 2003, followed by a slight decrease in
2004. The simplest explanation for the intensity variation is an increase in
stratospheric effective temperature from 155 +/- 3 K in 1985 to 176 +/- 3 K in
2003 (an average rate of 1.2 K/year), and subsequent decrease to 165 +/- 3 K in
2004. We also detected variation of the overall spectral structure of the
ethane band, specifically an apparent absorption structure in the central
portion of the band; this structure arises from coarse spectral sampling
coupled with a non-uniform response function within the detector elements. We
also report a probable direct detection of ethane emission on Uranus. The
deduced peak mole fraction is approximately an order of magnitude higher than
previous upper limits for Uranus. The model fit suggests an effective
temperature of 114 +/- 3 K for the globally-averaged stratosphere of Uranus,
which is consistent with recent measurements indicative of seasonal variation.Comment: Accepted for publication in ApJ. 16 pages, 10 figures, 2 table
Flight measurements of drag and base pressure of a fin-stabilized parabolic body of revolution (NACA RM-10) at different Reynolds numbers and at Mach numbers from 0.9 to 3.3
Flight Measurements of Drag and Base Pressure of a Fin-stabilized Parabolic Body of Revolution (NACA RM-10) at Different Reynolds Numbers and at Mach Numbers from 0.9 to 3.3
Electrodynamic Radiation Reaction and General Relativity
We argue that the well-known problem of the instabilities associated with the
self-forces (radiation reaction forces) in classical electrodynamics are
possibly stabilized by the introduction of gravitational forces via general
relativity
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