1,173 research outputs found
Engineering superpositions of displaced number states of a trapped ion
We present a protocol that permits the generation of a subtle with
superposition with 2^(l+1) displaced number states on a circle in phase space
as target state for the center-of-mass motion of a trapped ion. Through a
sequence of 'l' cycles involving the application of laser pulses and
no-fluorescence measurements, explicit expressions for the total duration of
laser pulses employed in the sequence and probability of getting the ion in the
upper electronic state during the 'l' cycles are obtained and analyzed in
detail. Furthermore, assuming that the effective relaxation process of a
trapped ion can be described in the framework of the standard master equation
for the damped harmonic oscillator, we investigate the degradation of the
quantum interference effects inherent to superpositions via Wigner function.Comment: 14 pages, 10 figure
Electroanatomic substrate of atrial fibrillation in patients after COVID-19
Aim. To determine the features of left atrial electroanatomic structure and the arrhythmia substrate in patients with atrial fibrillation (AF) after coronavirus disease 2019 (COVID-19).Material and methods. The pilot study included 20 patients with AF who underwent catheter radiofrequency ablation. Ten patients had COVID-19 and 10 patients were included as a control group. AF substrate was identified using anatomic and bipolar mapping. Zones with following amplitudes were analyzed: <0,25 mV, <0,5 mV, from 0,5 to 0,75 mV inclusive, and >0,75 mV. Left atrial volume was determined based on anatomic map.Results. The groups were homogeneous in AF type, number of patients after prior pulmonary vein isolation, and heart rate during mapping. In the COVID-19 group, there was a higher area of fibrous zones with an amplitude of <0,25 mV (51,5±16,6% vs 29,1±16,1% in the control group, p=0,007), <0,5 mV (76,7±11,5% vs 45,6±22,7% in the control group, p=0,001) and a lower area of intact myocardium with an amplitude >0,75 mV (11,6±8,0% vs 45,0±25,0% in the control group, p=0,001). In 7 COVID-19 patients, the posterior wall was isolated due to low-amplitude zones. Of these, three patients underwent surgery for the first time. According to ROC analysis, in patients after COVID-19, fibrous tissue (<0,5 mV) occupies more than half of the area, while normal tissue (>0,75 mV) — ~30% or less.Conclusion. This study shows that SARS-CoV-2 infection may cause left atrial remodeling in the form of diffuse fibrosis. The arrhythmia substrate in patients after COVID-19 can be localized not only in pulmonary vein mouths, but also in other left atrial areas. This must be taken into account before ablation, even if the procedure is being performed for the first time. It is recommended to perform amplitude mapping for all patients who have had SARS-CoV-2 infection in order to identify fibrous zones and plan the operation extent
Future developments in brain-machine interface research
Neuroprosthetic devices based on brain-machine interface technology hold promise for the restoration of body mobility in patients suffering from devastating motor deficits caused by brain injury, neurologic diseases and limb loss. During the last decade, considerable progress has been achieved in this multidisciplinary research, mainly in the brain-machine interface that enacts upper-limb functionality. However, a considerable number of problems need to be resolved before fully functional limb neuroprostheses can be built. To move towards developing neuroprosthetic devices for humans, brain-machine interface research has to address a number of issues related to improving the quality of neuronal recordings, achieving stable, long-term performance, and extending the brain-machine interface approach to a broad range of motor and sensory functions. Here, we review the future steps that are part of the strategic plan of the Duke University Center for Neuroengineering, and its partners, the Brazilian National Institute of Brain-Machine Interfaces and the École Polytechnique Fédérale de Lausanne (EPFL) Center for Neuroprosthetics, to bring this new technology to clinical fruition
Unifying darko-lepto-genesis with scalar triplet inflation
We present a scalar triplet extension of the standard model to unify the
origin of inflation with neutrino mass, asymmetric dark matter and
leptogenesis. In presence of non-minimal couplings to gravity the scalar
triplet, mixed with the standard model Higgs, plays the role of inflaton in the
early Universe, while its decay to SM Higgs, lepton and dark matter
simultaneously generate an asymmetry in the visible and dark matter sectors. On
the other hand, in the low energy effective theory the induced vacuum
expectation value of the triplet gives sub-eV Majorana masses to active
neutrinos. We investigate the model parameter space leading to successful
inflation as well as the observed dark matter to baryon abundance. Assuming the
standard model like Higgs mass to be at 125-126 GeV, we found that the mass
scale of the scalar triplet to be ~ O(10^9) GeV and its trilinear coupling to
doublet Higgs is ~ 0.09 so that it not only evades the possibility of having a
metastable vacuum in the standard model, but also lead to a rich
phenomenological consequences as stated above. Moreover, we found that the
scalar triplet inflation strongly constrains the quartic couplings, while
allowing for a wide range of Yukawa couplings which generate the CP asymmetries
in the visible and dark matter sectors.Comment: (v1) 29 pages, 11 figures; (v2) 30 pages, 1 figure added and
discussions expanded, to appear in Nuclear Physics
A perfect match of MSSM-like orbifold and resolution models via anomalies
Compactification of the heterotic string on toroidal orbifolds is a promising
set-up for the construction of realistic unified models of particle physics.
The target space dynamics of such models, however, drives them slightly away
from the orbifold point in moduli space. This resolves curvature singularities,
but makes the string computations very difficult. On these smooth manifolds we
have to rely on an effective supergravity approximation in the large volume
limit. By comparing an orbifold example with its blow-up version, we try to
transfer the computational power of the orbifold to the smooth manifold. Using
local properties, we establish a perfect map of the the chiral spectra as well
as the (local) anomalies of these models. A key element in this discussion is
the Green-Schwarz anomaly polynomial. It allows us to identify those
redefinitions of chiral fields and localized axions in the blow-up process
which are relevant for the interactions (such as Yukawa-couplings) in the model
on the smooth space.Comment: 2+35 pages, 1 figur
Azimuthal anisotropy and correlations at large transverse momenta in and Au+Au collisions at = 200 GeV
Results on high transverse momentum charged particle emission with respect to
the reaction plane are presented for Au+Au collisions at =
200 GeV. Two- and four-particle correlations results are presented as well as a
comparison of azimuthal correlations in Au+Au collisions to those in at
the same energy. Elliptic anisotropy, , is found to reach its maximum at
GeV/c, then decrease slowly and remain significant up to
-- 10 GeV/c. Stronger suppression is found in the back-to-back
high- particle correlations for particles emitted out-of-plane compared to
those emitted in-plane. The centrality dependence of at intermediate
is compared to simple models based on jet quenching.Comment: 4 figures. Published version as PRL 93, 252301 (2004
Azimuthal anisotropy in Au+Au collisions at sqrtsNN = 200 GeV
The results from the STAR Collaboration on directed flow (v_1), elliptic flow
(v_2), and the fourth harmonic (v_4) in the anisotropic azimuthal distribution
of particles from Au+Au collisions at sqrtsNN = 200 GeV are summarized and
compared with results from other experiments and theoretical models. Results
for identified particles are presented and fit with a Blast Wave model.
Different anisotropic flow analysis methods are compared and nonflow effects
are extracted from the data. For v_2, scaling with the number of constituent
quarks and parton coalescence is discussed. For v_4, scaling with v_2^2 and
quark coalescence is discussed.Comment: 26 pages. As accepted by Phys. Rev. C. Text rearranged, figures
modified, but data the same. However, in Fig. 35 the hydro calculations are
corrected in this version. The data tables are available at
http://www.star.bnl.gov/central/publications/ by searching for "flow" and
then this pape
Measurement of W Polarisation at LEP
The three different helicity states of W bosons produced in the reaction e+
e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W
decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to
measure the polarisation of W bosons, and its dependence on the W boson
production angle. The fraction of longitudinally polarised W bosons is measured
to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and
the second systematic, in agreement with the Standard Model expectation
Rapidity and Centrality Dependence of Proton and Anti-proton Production from Au+Au Collisions at sqrt(sNN) = 130GeV
We report on the rapidity and centrality dependence of proton and anti-proton
transverse mass distributions from Au+Au collisions at sqrt(sNN) = 130GeV as
measured by the STAR experiment at RHIC. Our results are from the rapidity and
transverse momentum range of |y|<0.5 and 0.35 <p_t<1.00GeV/c. For both protons
and anti-protons, transverse mass distributions become more convex from
peripheral to central collisions demonstrating characteristics of collective
expansion. The measured rapidity distributions and the mean transverse momenta
versus rapidity are flat within |y|<0.5. Comparisons of our data with results
from model calculations indicate that in order to obtain a consistent picture
of the proton(anti-proton) yields and transverse mass distributions the
possibility of pre-hadronic collective expansion may have to be taken into
account.Comment: 4 pages, 3 figures, 1 table, submitted to PR
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