60,472 research outputs found
Expectations, credibility, and disinflation in a small macroeconomic model
A study of the effects of expectations and central bank credibility on the economy's dynamic transition path during a disinflation. Using a version of the Fuhrer-Moore model, it compares simulations under different specifications that vary according to the way expectations are formed and the degree of central bank credibility.Monetary policy ; Inflation (Finance) ; Business cycles
Anomalous Rashba spin-orbit interaction in InAs/GaSb quantum wells
We investigate theoretically the Rashba spin-orbit interaction in InAs/GaSb
quantum wells(QWs). We find that the Rashba spin-splitting (RSS) depends
sensitively on the thickness of the InAs layer. The RSS exhibits nonlinear
behavior for narrow InAs/GaSb QWs and the oscillating feature for wide
InAs/GaSb QWs. The nonlinear and oscillating behaviors arise from the weakened
and enhanced interband coupling. The RSS also show asymmetric features respect
to the direction of the external electric field.Comment: 3 pages, 4 figures. Appl. Phys. Lett. (in press
Quantum field and uniformly accelerated oscillator
We present an exact treatment of the influences on a quantum scalar field in
its Minkowski vacuum state induced by coupling of the field to a uniformly
accelerated harmonic oscillator. We show that there are no radiation from the
oscillator in the point of view of a uniformly accelerating observer. On the
other hand, there are radiations in the point of view of an inertial observer.
It is shown that Einstein-Podolsky-Rosen (EPR) like correlations of Rindler
particles in Minkowski vacuum states are modified by a phase factor in front of
the momentum-symmetric Rindler operators. The exact quantization of a
time-dependent oscillator coupled to a massless scalar field was given.Comment: 28 pages, LaTe
A Model Behind the Standard Model
In spite of its many successes, the Standard Model makes many empirical
assumptions in the Higgs and fermion sectors for which a deeper theoretical
basis is sought. Starting from the usual gauge symmetry plus the 3 assumptions: (A) scalar fields as vielbeins in
internal symmetry space \cite{framevec}, (B) the ``confinement picture'' of
symmetry breaking \cite{tHooft,Banovici}, (C) generations as ``dual'' to colour
\cite{genmixdsm}, we are led to a scheme which offers: (I) a geometrical
significance to scalar fields, (II) a theoretical criterion on what scalar
fields are to be introduced, (III) a partial explanation of why appears
broken while confines, (IV) baryon-lepton number (B - L) conservation,
(V) the standard electroweak structure, (VI) a 3-valued generation index for
leptons and quarks, and (VII) a dynamical system with all the essential
features of an earlier phenomenological model \cite{genmixdsm} which gave a
good description of the known mass and mixing patterns of quarks and leptons
including neutrino oscillations. There are other implications the consistency
of which with experiment, however, has not yet been systematically explored. A
possible outcome is a whole new branch of particle spectroscopy from
confinement, potentially as rich in details as that of hadrons from colour
confinement, which will be accessible to experiment at high energy.Comment: 66 pages, added new material on phenomenology, and some new
reference
Computation of topside ionograms from N/h/ profiles
Computation of topside ionograms from electron concentration profile
Electric field induced charge noise in doped silicon: ionization of phosphorus donors
We report low frequency charge noise measurement on silicon substrates with
different phosphorus doping densities. The measurements are performed with
aluminum single electron transistors (SETs) at millikelvin temperatures where
the substrates are in the insulating regime. By measuring the SET Coulomb
oscillations, we find a gate voltage dependent charge noise on the more heavily
doped substrate. This charge noise, which is seen to have a 1/f spectrum, is
attributed to the electric field induced tunneling of electrons from their
phosphorus donor potentials.Comment: 4 page, 3 figure
Calculation of composition distribution of ultrafine ion-H2O-H2SO4 clusters using a modified binary ion nucleation theory
Thomson's ion nucleation theory was modified to include the effects of curvature dependence of the microscopic surface tension of field dependent, nonlinear, dielectric properties of the liquid; and of sulfuric acid hydrate formation in binary mixtures of water and sulfuric acid vapors. The modified theory leads to a broadening of the ion cluster spectrum, and shifts it towards larger numbers of H2O and H2SO4 molecules. Whether there is more shifting towards larger numbers of H2O or H2SO4 molecules depends on the relative humidity and relative acidity of the mixture. Usually, a broadening of the spectrum is accompanied by a lowering of the mean cluster intensity. For fixed values of relative humidity and relative acidity, a similar broadening pattern is observed when the temperature is lowered. These features of the modified theory illustrate that a trace of sulfuric acid can facilitate the formation of ultrafine, stable, prenucleation ion clusters as well as the growth of the prenucleation ion clusters towards the critical saddle point conditions, even with low values of relative humidity and relative acidity
Signal quality measures for unsupervised blood pressure measurement
Accurate systolic and diastolic pressure estimation, using automated blood pressure measurement, is difficult to achieve when the transduced signals are contaminated with noise or interference, such as movement artifact. This study presents an algorithm for automated signal quality assessment in blood pressure measurement by determining the feasibility of accurately detecting systolic and diastolic pressures when corrupted with various levels of movement artifact. The performance of the proposed algorithm is compared to a manually annotated reference scoring (RS). Based on visual representations and audible playback of Korotkoff sounds, the creation of the RS involved two experts identifying sections of the recorded sounds and annotating sections of noise contamination. The experts determined the systolic and diastolic pressure in 100 recorded Korotkoff sound recordings, using a simultaneous electrocardiograph as a reference signal. The recorded Korotkoff sounds were acquired from 25 healthy subjects (16 men and 9 women) with a total of four measurements per subject. Two of these measurements contained purposely induced noise artifact caused by subject movement. Morphological changes in the cuff pressure signal and the width of the Korotkoff pulse were extracted features which were believed to be correlated with the noise presence in the recorded Korotkoff sounds. Verification of reliable Korotkoff pulses was also performed using extracted features from the oscillometric waveform as recorded from the inflatable cuff. The time between an identified noise section and a verified Korotkoff pulse was the key feature used to determine the validity of possible systolic and diastolic pressures in noise contaminated Korotkoff sounds. The performance of the algorithm was assessed based on the ability to: verify if a signal was contaminated with any noise; the accuracy, sensitivity and specificity of this noise classification, and the systolic and diastolic pressure differences between the result obtained from the algorithm and the RS. 90% of the actual noise contaminated signals were correctly identified, and a sample-wise accuracy, sensitivity and specificity of 97.0%, 80.61% and 98.16%, respectively, were obtained from 100 pooled signals. The mean systolic and diastolic differences were 0.37 ± 3.31 and 3.10 ± 5.46 mmHg, respectively, when the artifact detection algorithm was utilized, with the algorithm correctly determined if the signal was clean enough to attempt an estimation of systolic or diastolic pressures in 93% of blood pressure measurements
Hamiltonian Theory of Adiabatic Motion of Relativistic Charged Particles
A general Hamiltonian theory for the adiabatic motion of relativistic charged
particles confined by slowly-varying background electromagnetic fields is
presented based on a unified Lie-transform perturbation analysis in extended
phase space (which includes energy and time as independent coordinates) for all
three adiabatic invariants. First, the guiding-center equations of motion for a
relativistic particle are derived from the particle Lagrangian. Covariant
aspects of the resulting relativistic guiding-center equations of motion are
discussed and contrasted with previous works. Next, the second and third
invariants for the bounce motion and drift motion, respectively, are obtained
by successively removing the bounce phase and the drift phase from the
guiding-center Lagrangian. First-order corrections to the second and third
adiabatic invariants for a relativistic particle are derived. These results
simplify and generalize previous works to all three adiabatic motions of
relativistic magnetically-trapped particles.Comment: 20 pages, LaTeX, to appear in Physics of Plasmas (Aug, 2007
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