6,167 research outputs found
Finite VEVs from a Large Distance Vacuum Wave Functional
We show how to compute vacuum expectation values from derivative expansions
of the vacuum wave functional. Such expansions appear to be valid only for
slowly varying fields, but by exploiting analyticity in a complex scale
parameter we can reconstruct the contribution from rapidly varying fields.Comment: 39 pages, 16 figures, LaTeX2e using package graphic
Risk stratifiers for arrhythmic and non-arrhythmic mortality after acute myocardial infarction
Open Access. Publicado online: 2-Jul-2018The effective discrimination between patients at risk of Arrhythmic Mortality (AM) and Non-Arrhythmic Mortality (NAM) constitutes one of the important unmet clinical needs. Successful risk assessment based on Electrocardiography (ECG) records is greatly improved by the combination of different indices reflecting not only the pathological substrate but also the autonomic regulation of cardiac electrophysiology. This study assesses the cardiac risk stratification capacity of two new Heart Rate Variability (HRV) parameters, Breath Concurrence 6 (BC6) -sinusoidal RR variability of 6 heart beats per breath cycle- and Primary Ectopia (PE) -presence of early ventricular contractions of any etiology- together with the Deceleration Capacity (DC). While BC6 characterizes the response to physiological and pathophysiological stimuli, PE qualifies autonomic cardiac electrophysiology. The analysis of the European Myocardial Infarct Amiodarone Trial (EMIAT) database indicates that BC6 is related with the risk of Arrhythmic Mortality (AM) and PE with the risk of Non-Arrhythmic Mortality. BC6 is the only single parameter that significantly discriminates between AM and NAM. While the combination of BC6 and DC contributes to the identification of AM risk, PE together with DC improves the prediction of NAM in patients with severe ischemic heart disease
Surface electromyographic control of a novel phonemic interface for speech synthesis
Many individuals with minimal movement capabilities use AAC to communicate. These individuals require both an interface with which to construct a message (e.g., a grid of letters) and an input modality with which to select targets. This study evaluated the interaction of two such systems: (a) an input modality using surface electromyography (sEMG) of spared facial musculature, and (b) an onscreen interface from which users select phonemic targets. These systems were evaluated in two experiments: (a) participants without motor impairments used the systems during a series of eight training sessions, and (b) one individual who uses AAC used the systems for two sessions. Both the phonemic interface and the electromyographic cursor show promise for future AAC applications.F31 DC014872 - NIDCD NIH HHS; R01 DC002852 - NIDCD NIH HHS; R01 DC007683 - NIDCD NIH HHS; T90 DA032484 - NIDA NIH HHShttps://www.ncbi.nlm.nih.gov/pubmed/?term=Surface+electromyographic+control+of+a+novel+phonemic+interface+for+speech+synthesishttps://www.ncbi.nlm.nih.gov/pubmed/?term=Surface+electromyographic+control+of+a+novel+phonemic+interface+for+speech+synthesisPublished versio
The Speed of Light and the Hubble Parameter: The Mass-Boom Effect
We prove here that Newtons universal gravitation and momentum conservation
laws together reproduce Weinbergs relation. It is shown that the Hubble
parameter H must be built in this relation, or equivalently the age of the
Universe t. Using a wave-to-particle interaction technique we then prove that
the speed of light c decreases with cosmological time, and that c is
proportional to the Hubble parameter H. We see the expansion of the Universe as
a local effect due to the LAB value of the speed of light co taken as constant.
We present a generalized red shift law and find a predicted acceleration for
photons that agrees well with the result from Pioneer 10/11 anomalous
acceleration. We finally present a cosmological model coherent with the above
results that we call the Mass-Boom. It has a linear increase of mass m with
time as a result of the speed of light c linear decrease with time, and the
conservation of momentum mc. We obtain the baryonic mass parameter equal to the
curvature parameter, omega m = omega k, so that the model is of the type of the
Einstein static, closed, finite, spherical, unlimited, with zero cosmological
constant. This model is the cosmological view as seen by photons, neutrinos,
tachyons etc. in contrast with the local view, the LAB reference. Neither dark
matter nor dark energy is required by this model. With an initial constant
speed of light during a short time we get inflation (an exponential expansion).
This converts, during the inflation time, the Plancks fluctuation length of
10-33 cm to the present size of the Universe (about 1028 cm, constant from then
on). Thereafter the Mass-Boom takes care to bring the initial values of the
Universe (about 1015 gr) to the value at the present time of about 1055 gr.Comment: 15 pages, presented at the 9th Symposium on "Frontiers of Fundamental
Physics", 7-9 Jan. 2008, University of Udine, Italy. Changed content
Resonating bipolarons
Electrons coupled to local lattice deformations end up in selftrapped
localized molecular states involving their binding into bipolarons when the
coupling is stronger than a certain critical value. Below that value they exist
as essentially itinerant electrons. We propose that the abrupt crossover
between the two regimes can be described by resonant pairing similar to the
Feshbach resonance in binary atomic collision processes. Given the
intrinsically local nature of the exchange of pairs of itinerant electrons and
localized bipolarons, we demonstrate the occurrence of such a resonance on a
finite-size cluster made out of metallic atoms surrounding a polaronic ligand
center.Comment: 7 pages, 4 figures, to be published in Europhysics Letter
Water vapor emission from IRC+10216 and other carbon-rich stars: model predictions and prospects for multitransition observations
We have modeled the emission of H2O rotational lines from the extreme C-rich
star IRC+10216. Our treatment of the excitation of H2O emissions takes into
account the excitation of H2O both through collisions, and through the pumping
of the nu2 and nu3 vibrational states by dust emission and subsequent decay to
the ground state. Regardless of the spatial distribution of the water
molecules, the H2O 1_{10}-1_{01} line at 557 GHz observed by the Submillimeter
Wave Astronomy Satellite (SWAS) is found to be pumped primarily through the
absorption of dust-emitted photons at 6 m in the nu2 band. As noted by
previous authors, the inclusion of radiative pumping lowers the ortho-H2O
abundance required to account for the 557 GHz emission, which is found to be
(0.5-1)x10^{-7} if the presence of H2O is a consequence of vaporization of
orbiting comets or Fischer-Tropsch catalysis. Predictions for other
submillimeter H2O lines that can be observed by the Herschel Space Observatory
(HSO) are reported. Multitransition HSO observations promise to reveal the
spatial distribution of the circumstellar water vapor, discriminating among the
several hypotheses that have been proposed for the origin of the H2O vapor in
the envelope of IRC+10216. We also show that, for observations with HSO, the
H2O 1_{10}-1_{01} 557 GHz line affords the greatest sensitivity in searching
for H2O in other C-rich AGB stars.Comment: 35 pages, 12 figures, to be published in The Astrophysical Journa
Non-expanding universe: a cosmological system of units
The product of two empirical constants, the dimensionless fine structure
constant and the von Klitzing constant (an electrical resistance), turns out to
be an exact dimensionless number. Then the accuracy and cosmological time
variation (if any) of these two constants are tied. Also this product defines a
natural unit of electrical resistance, the inverse of a quantum of conductance.
When the speed of light c is taken away from the fine structure constant, as
has been shown elsewhere, its constancy implies the constancy of the ratio e2/h
(the inverse of the von Klitzing constant), e the charge of the electron and h
Planck constant. This forces the charge of the electron e to be constant as
long as the action h (an angular momentum) is a true constant too. From the
constancy of the Rydberg constant the Compton wavelength, h/mc, is then a true
constant and consequently there is no expansion at the quantum mechanical
level. The momentum mc is also a true constant and then general relativity
predicts that the universe is not expanding, as shown elsewhere. The time
variation of the speed of light explains the observed Hubble red shift. And
there is a mass-boom effect. From this a coherent cosmological system of
constant units can be defined.Comment: 8 page
Algebraic (2,2)-transformation groups
In this paper we determine all algebraic trans-formation groups G, defined over an algebraical-ly closed field k, which operate transitively, but not primitively, on a variety M, provided the following conditions are fulfilled. We ask that the (non-effective) action of G on the va-riety of blocks is sharply 2-transitive, as well as the action on a block X of the normalizer Gx. Also we require sharp transitivity on pairs (X,Y)of independent points of M, i.e. points con-tained in different blocks
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