21,163 research outputs found
Sensitivity of CO2 migration estimation on reservoir temperature and pressure uncertainty
The density and viscosity of supercritical CO2 are sensitive to pressure and temperature (PT) while the viscosity of brine is sensitive primarily to temperature. Oil field PT data in the vicinity of WESTCARB's Phase III injection pilot test site in the southern San Joaquin Valley, California, show a range of PT values, indicating either PT uncertainty or variability. Numerical simulation results across the range of likely PT indicate brine viscosity variation causes virtually no difference in plume evolution and final size, but CO2 density variation causes a large difference. Relative ultimate plume size is almost directly proportional to the relative difference in brine and CO2 density (buoyancy flow). The majority of the difference in plume size occurs during and shortly after the cessation of injection. © 2009 Lawrence Berkeley National Laboratory
Einstein and Jordan frames reconciled: a frame-invariant approach to scalar-tensor cosmology
Scalar-Tensor theories of gravity can be formulated in different frames, most
notably, the Einstein and the Jordan one. While some debate still persists in
the literature on the physical status of the different frames, a frame
transformation in Scalar-Tensor theories amounts to a local redefinition of the
metric, and then should not affect physical results. We analyze the issue in a
cosmological context. In particular, we define all the relevant observables
(redshift, distances, cross-sections, ...) in terms of frame-independent
quantities. Then, we give a frame-independent formulation of the Boltzmann
equation, and outline its use in relevant examples such as particle freeze-out
and the evolution of the CMB photon distribution function. Finally, we derive
the gravitational equations for the frame-independent quantities at first order
in perturbation theory. From a practical point of view, the present approach
allows the simultaneous implementation of the good aspects of the two frames in
a clear and straightforward way.Comment: 15 pages, matches version to be published on Phys. Rev.
Thermal correlators of anyons in two dimensions
The anyon fields have trivial -commutator for not integer.
For integer the commutators become temperature-dependent operator
valued distributions. The -point functions do not factorize as for quasifree
states.Comment: 14 pages, LaTeX (misprints corrected, a reference added
Decreased myocardial injury and improved contractility after administration of a peptide derived against the alpha-interacting domain of the L-type calcium channel.
BackgroundMyocardial infarction remains the leading cause of morbidity and mortality associated with coronary artery disease. The L-type calcium channel (IC a-L) is critical to excitation and contraction. Activation of the channel also alters mitochondrial function. Here, we investigated whether application of a alpha-interacting domain/transactivator of transcription (AID-TAT) peptide, which immobilizes the auxiliary β2 subunit of the channel and decreases metabolic demand, could alter mitochondrial function and myocardial injury.Methods and resultsTreatment with AID-TAT peptide decreased ischemia-reperfusion injury in guinea-pig hearts ex vivo (n=11) and in rats in vivo (n=9) assessed with uptake of nitroblue tetrazolium, release of creatine kinase, and lactate dehydrogenase. Contractility (assessed with catheterization of the left ventricle) was improved after application of AID-TAT peptide in hearts ex vivo (n=6) and in vivo (n=8) up to 12 weeks before sacrifice. In search of the mechanism for the effect, we found that intracellular calcium ([Ca(2+)]i, Fura-2), superoxide production (dihydroethidium fluorescence), mitochondrial membrane potential (Ψm, JC-1 fluorescence), reduced nicotinamide adenine dinucleotide production, and flavoprotein oxidation (autofluorescence) are decreased after application of AID-TAT peptide.ConclusionsApplication of AID-TAT peptide significantly decreased infarct size and supported contractility up to 12 weeks postcoronary artery occlusion as a result of a decrease in metabolic demand during reperfusion
Ultrasensitive Beam Deflection Measurement via Interferometric Weak Value Amplification
We report on the use of an interferometric weak value technique to amplify
very small transverse deflections of an optical beam. By entangling the beam's
transverse degrees of freedom with the which-path states of a Sagnac
interferometer, it is possible to realize an optical amplifier for polarization
independent deflections. The theory for the interferometric weak value
amplification method is presented along with the experimental results, which
are in good agreement. Of particular interest, we measured the angular
deflection of a mirror down to 560 femtoradians and the linear travel of a
piezo actuator down to 20 femtometers
Precision frequency measurements with interferometric weak values
We demonstrate an experiment which utilizes a Sagnac interferometer to
measure a change in optical frequency of 129 kHz per root Hz with only 2 mW of
continuous wave, single mode input power. We describe the measurement of a weak
value and show how even higher frequency sensitivities may be obtained over a
bandwidth of several nanometers. This technique has many possible applications,
such as precision relative frequency measurements and laser locking without the
use of atomic lines.Comment: 4 pages, 3 figures, published in PR
An astronomical search for evidence of new physics: Limits on gravity-induced birefringence from the magnetic white dwarf RE J0317-853
The coupling of the electromagnetic field directly with gravitational gauge
fields leads to new physical effects that can be tested using astronomical
data. Here we consider a particular case for closer scrutiny, a specific
nonminimal coupling of torsion to electromagnetism, which enters into a
metric-affine geometry of space-time. We show that under the assumption of this
nonminimal coupling, spacetime is birefringent in the presence of such a
gravitational field. This leads to the depolarization of light emitted from
extended astrophysical sources. We use polarimetric data of the magnetic white
dwarf to set strong constraints on the essential coupling
constant for this effect, giving k^2 \lsim (19 {m})^2 .Comment: Statements about Moffat's NGT modified. Accepted for publication in
Phys.Rev.
Optimizing the Signal to Noise Ratio of a Beam Deflection Measurement with Interferometric Weak Values
The amplification obtained using weak values is quantified through a detailed
investigation of the signal to noise ratio for an optical beam deflection
measurement. We show that for a given deflection, input power and beam radius,
the use of interferometric weak values allows one to obtain the optimum signal
to noise ratio using a coherent beam. This method has the advantage of reduced
technical noise and allows for the use of detectors with a low saturation
intensity. We report on an experiment which improves the signal to noise ratio
for a beam deflection measurement by a factor of 54 when compared to a
measurement using the same beam size and a quantum limited detector
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