180 research outputs found
Closing and opening phase variability in dysphonia
Four examples of the use of vocal fold contact phase measurement are discussed for unilateral paresis. In each case this aspect of voice quality is of greater importance than the physical measurement of loudness and pitch related parameters. For three of the cases electro-stimulation has been used as a main part of the treatment. Phonation in both connected speech and, for comparison, in sustained sound production has been used with electro-laryngograph / egg signals providing the basis for measurement. The main new descriptors that have been found to be useful relate to: vocal fold closure and closure duration regularities and distributions; but reference is also made to related measures of peak acoustic amplitude. The new measures described give, in some cases, quite striking results that are of auditory significance and potentially of clinical value
Fulde-Ferrell-Larkin-Ovchinnikov phase in the presence of pair hopping interaction
The recent experimental support for the presence of the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase in the CeCoIn5 directed the
attention towards the mechanisms responsible for this type of
superconductivity. We investigate the FFLO state in a model where
on--site/inter--site pairing coexists with repulsive pair hopping interaction.
The latter interaction is interesting in that it leads to pairing with nonzero
momentum of the Cooper pairs even in the absence of the external magnetic field
(the so-called eta-pairing). It turns out that depending on the strength of the
pair hopping interaction the magnetic field can induce one of two types of the
FFLO phase with different spatial modulations of the order parameter. It is
argued that the properties of the FFLO phase may give information about the
magnitude of the pair hopping interaction. We also show that eta-pairing and
d-wave superconductivity may coexist in the FFLO state. It holds true also for
superconductors which in the absence of magnetic field are of pure d-wave type.Comment: 16 pages, 8 figure
Specific heat study of Fulde–Ferrell–Larkin–Ovchinnikov superconducting states in multibands materials - Iron-based Systems
The Fulde-Ferrell-Larkin-Ovchinnikov phase is the superconducting state for which the Cooper pairs have non-zero total momentum. From the time of conception of this phase, many groups have been searching for a realization of the state. Here we describe a proposal of experimental verification of this state in the case of multibands systems, by carrying out the specific-heat measurement
Interplay between pairing and correlations in spin-polarized bound states
We investigate the single and multiple defects embedded in a superconducting
host, studying interplay between the proximity induced pairing and
interactions. We explore influence of the spin-orbit coupling on energies,
polarization and spatial patterns of the bound (Yu-Shiba-Rusinov) states of
magnetic impurities in 2-dimensional square lattice. We also address the
peculiar bound states in the proximitized Rashba chain, resembling the Majorana
quasiparticles, focusing on their magnetic polarization which has been recently
reported by S. Jeon et al., [Science 358, 772 (2017)]. Finally, we study
leakage of these polarized Majorana quasiparticles on the side-attached
nanoscopic regions and confront them with the subgap Kondo effect near to the
singlet-doublet phase transition.Comment: 10 pages, 9 figure
Coexistence of superconductivity and incommensurate magnetic order
The influence of incommensurate spin density waves (SDW) on superconductivity
in unconventional superconductors is studied by means of the Bogolubov-de
Gennes (BdG) equations. Exploiting translational symmetries of a magnetically
ordered two-dimensional system we propose an approach that allows to solve the
BdG equations on much larger clusters than it is usually possible for
inhomogeneous systems. Applying this approach we demonstrate that the presence
of incommensurate spin density waves induces real-space inhomogeneity of the
superconducting order parameter even in the absence of external magnetic field.
In this case a homogeneous order parameter of the
Bardeen-Cooper-Schrieffer-type superconducting state is slightly modulated, or
equivalently, a small fraction of the charge carriers form Cooper pairs with
non-zero total momentum. However, when a sufficiently strong magnetic field is
applied, the homogeneous component of the order parameter is suppressed and the
system transits to the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, where the
order parameter oscillates changing sign. We show that for s-wave pairing the
presence of external magnetic field diminishes the destructive influence of the
SDW order on superconductivity. A simple explanation of this effect is also
proposed.Comment: To appear in Phys. Rev.
Superexchange Interaction in Insulating EuZnP
We report magnetic and transport properties of single-crystalline
EuZnP, which has trigonal CaAlSi-type crystal structure and
orders antiferromagnetically at 23~K. Easy -plane
magneto-crystalline anisotropy was confirmed from the magnetization isotherms,
measured with a magnetic field applied along different crystallographic
directions (-plane and -axis). Positive Curie-Weiss temperature
indicates dominating ferromagnetic correlations. Electrical resistivity
displays insulating behavior with a band-gap of 0.177~eV, which
decreases to 0.13~eV upon application of a high magnetic field. We
explained the intriguing presence of magnetic interactions in an intermetallic
insulator by the mechanism of extended superexchange, with phosphorus as an
anion mediator, which is further supported by our analysis of the charge and
spin density distributions. We constructed the effective Heisenberg model, with
exchange parameters derived from the \textit{ab initio} DFT calculations, and
employed it in Monte-Carlo simulations, which correctly reproduced the
experimental value of N\'eel temperature
Ab initio and nuclear inelastic scattering studies of FeSi/GaAs heterostructures
The structure and dynamical properties of the FeSi/GaAs(001) interface
are investigated by density functional theory and nuclear inelastic scattering
measurements. The stability of four different atomic configurations of the
FeSi/GaAs multilayers is analyzed by calculating the formation energies and
phonon dispersion curves. The differences in charge density, magnetization, and
electronic density of states between the configurations are examined. Our
calculations unveil that magnetic moments of the Fe atoms tend to align in a
plane parallel to the interface, along the [110] direction of the FeSi
crystallographic unit cell. In some configurations, the spin polarization of
interface layers is larger than that of bulk FeSi. The effect of the
interface on element-specific and layer-resolved phonon density of states is
discussed. The Fe-partial phonon density of states measured for the FeSi
layer thickness of three monolayers is compared with theoretical results
obtained for each interface atomic configuration. The best agreement is found
for one of the configurations with a mixed Fe-Si interface layer, which
reproduces the anomalous enhancement of the phonon density of states below 10
meVComment: 14 pages, 9 figures, 4 table
An Evaluation of Otopathology in the MOV-13 Transgenic Mutant Mouse a
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72482/1/j.1749-6632.1991.tb19595.x.pd
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