96 research outputs found
Hemodynamic phenotypes and its association with blood pressure changes at continuous positive airway pressure therapy in obstructive sleep apnoea hypertensive patients
Background. The goal of our study was to define the hemodynamic phenotypes in hypertensive patients with newly diagnosed obstructive sleep apnoea (OSA) using the individual modelling of hemodynamics derived from ambulatory blood pressure monitoring (ABPM), a method proposed by our group previously, and to assess its validity in blood pressure alterations secondary to continuous positive airway pressure (CPAP).
Material and methods. Thirty-three hypertensive patients with moderate-to-severe OSA were investigated. All patients underwent ABPM on two occasions: at baseline and after one week CPAP. The sets of BP indexes at first ABPM were used for individual modelling to define the hemodynamic phenotype (class) based on regression analyses; specifically, the phenotypes were defined for daytime, nighttime and for 24 hours. The CPAP therapy efficacy was predefined as improvement in BP nighttime decrease for additional 5% as compared to baseline ABPM. With reference to this criterion, patients were further classified as responders (who achieved this target), and non-responders.
Results. Only 21.2% of hypertensive patients with OSA had optimal hemodynamic phenotype (class H2), despite comprehensive antihypertensive therapy; most of the other patients were classified either as harmonic type (class H3; 39.4%), or of diastolic dysfunctional type (class D3; 15.2%). In the daytime period 18.2% of patients with OSA were classified as D1-class, which is associated with high risk of acute hypotensive episodes. Responders were more frequently characterized by phenotype H3 (daytime) vs. nonresponders: 53.3% and 5.6% respectively; P < 0.05. At nighttime non-responders were more likely to transform the different baseline classes into H3 and D2; P < 0.05 vs. responders.
Conclusion. Our study suggest utility of newly developed modelling based on hemodynamic BP indexes in the prediction of BP alterations secondary to CPAP in OSA hypertensive patients
Towards the All-Loop Worldsheet S Matrix for AdS3 Ă S3 Ă T4
We obtain the all-loop worldsheet S matrix for fundamental excitations on AdS3 Ă S3 Ă T4 by studying the off-shell symmetry algebra of the superspace action in light cone gauge. The massless modes, unaccounted for in earlier works, are automatically included in our treatment. Their exact dispersion relation is found to be nonrelativistic, of giant-magnon form, and their scattering is naturally well defined. This opens the way to a complete investigation of AdS3/CFT2 integrability
Entanglement and transport through correlated quantum dot
We study quantum entanglement in a single-level quantum dot in the
linear-response regime. The results show, that the maximal quantum value of the
conductance 2e^2/h not always match the maximal entanglement. The pairwise
entanglement between the quantum dot and the nearest atom of the lead is also
analyzed by utilizing the Wootters formula for charge and spin degrees of
freedom separately. The coexistence of zero concurrence and the maximal
conductance is observed for low values of the dot-lead hybridization. Moreover,
the pairwise concurrence vanish simultaneously for charge and spin degrees of
freedom, when the Kondo resonance is present in the system. The values of a
Kondo temperature, corresponding to the zero-concurrence boundary, are also
provided.Comment: Presented on the International Conference "Nanoelectronics '06", 7-8
January 2006, Lancaster, U
Landau-Lifshitz sigma-models, fermions and the AdS/CFT correspondence
We define Landau-Lifshitz sigma models on general coset space , with
a maximal stability sub-group of . These are non-relativistic models that
have -valued N\"other charges, local invariance and are classically
integrable. Using this definition, we construct the
Landau-Lifshitz sigma-model. This sigma model describes the thermodynamic limit
of the spin-chain Hamiltonian obtained from the complete one-loop dilatation
operator of the N=4 super Yang-Mills (SYM) theory. In the second part of the
paper, we identify a number of consistent truncations of the Type IIB
Green-Schwarz action on whose field content consists of two
real bosons and 4,8 or 16 real fermions. We show that -symmetry acts
trivially in these sub-sectors. In the context of the large spin limit of the
AdS/CFT correspondence, we map the Lagrangians of these sub-sectors to
corresponding truncations of the Landau-Lifshitz
sigma-model.Comment: 42 page
More on integrable structures of superstrings in AdS(4) x CP(3) and AdS(2) x S(2) x T(6) superbackgrounds
In this paper we continue the study, initiated in arXiv:1009.3498 and
arXiv:1104.1793, of the classical integrability of Green-Schwarz superstrings
in AdS(4) x CP(3) and AdS(2) x S(2) x T(6) superbackgrounds whose spectrum
contains non-supercoset worldsheet degrees of freedom corresponding to broken
supersymmetries in the bulk. We derive an explicit expression, to all orders in
the coset fermions and to second order in the non-coset fermions, which extends
the supercoset Lax connection in these backgrounds with terms depending on the
non-coset fermions. An important property of the obtained form of the Lax
connection is that it is invariant under Z_4-transformations of the
superisometry generators and the spectral parameter. This demonstrates that the
contribution of the non-coset fermions does not spoil the Z_4-symmetry of the
super-coset Lax connection which is of crucial importance for the application
of Bethe-ansatz techniques. The expressions describing the AdS(4) x CP(3) and
AdS(2) x S(2) x T(6) superstring sigma--models and their Lax connections have a
very similar form. This is because their amount of target-space supersymmetries
complement each other to 32=24+8, the maximal number of 10d type II
supersymmetries. As a byproduct, this similarity has allowed us to obtain the
form of the geometry of the complete type IIA AdS(2) x S(2) x T(6) superspace
to all orders in the coset fermions and to the second order in the non-coset
ones.Comment: 28 pages; v2: References adde
Dressing phases of AdS3/CFT2
We determine the all-loop dressing phases of the AdS3/CFT2 integrable system related to type IIB string theory on AdS3ĂS3ĂT4 by solving the recently found crossing relations and studying their singularity structure. The two resulting phases present a novel structure with respect to the ones appearing in AdS5/CFT4 and AdS4/CFT3. In the strongly coupled regime, their leading order reduces to the universal ArutyunovâFrolovâStaudacher phase as expected. We also compute their subleading order and compare it with recent one-loop perturbative results and comment on their weak-coupling expansion
Fano and Kondo resonance in electronic current through nanodevices
Electronic transport through a quantum dot strongly coupled to electrodes is
studied within a model with two conduction channels. It is shown that multiple
scattering and interference of transmitted waves through both channels lead to
Fano resonance associated with Kondo resonance. Interference effects are also
pronouncedly seen in transport through the Aharonov-Bohm ring with the Kondo
dot, where the current characteristics continuously evolve with the magnetic
flux.Comment: 4 pages, 3 figures,a typing error has been correcte
D-brane Spectrum and K-theory Constraints of D=4, N=1 Orientifolds
We study the spectrum of stable BPS and non-BPS D-branes in Z_2 x Z_2
orientifolds for all choices of discrete torsion between the orbifold and
orientifold generators. We compute the torsion K-theory charges in these D=4,
N=1 orientifold models directly from worldsheet conformal field theory, and
compare with the K-theory constraints obtained indirectly using D-brane probes.
The K-theory torsion charges derived here provide non-trivial constraints on
string model building. We also discuss regions of stability for non-BPS
D-branes in these examples.Comment: 40 pages, 5 table
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