Left ventricular apical rotation is associated with mitral annular function in healthy subjects. Results from the three-dimensional speckle-tracking echocardiographic MAGYAR-Healthy Study.

INTRODUCTION: Left ventricular (LV) twist is considered an essential part of LV function due to oppositely directed LV basal and apical rotations. Several factors could play a role in determining LV rotational mechanics in normal circumstances. This study aimed to investigate the relationship between LV rotational mechanics and mitral annular (MA) size and function in healthy subjects. METHODS: The study comprised 118 healthy adult volunteers (mean age: 31.5 ± 11.8 years, 50 males). All subjects had undergone complete two-dimensional (2D) Doppler echocardiography and three-dimensional speckle-tracking echocardiography (3DSTE) at the same time by the same echocardiography equipment. RESULTS: The normal mean LV apical and basal rotations proved to be 9.57 ± 3.33 and -3.75 ± 1.98°, respectively. LV apical rotation correlated with end-systolic MA diameter, area, perimeter, fractional area change, and fractional shortening, but did not correlate with any end-diastolic mitral annular morphologic parameters. The logistic regression model identified MA fractional area change as an independent predictor of ≤6° left ventricular apical rotation (P < 0.003). CONCLUSIONS: Correlations could be detected between apical LV rotation and end-systolic MA size and function, suggesting relationships between MA dimensions and function and LV rotational mechanics.

The right atrium in idiopathic hypereosinophilic syndrome : Insights from the 3D speckle tracking echocardiographic MAGYAR-Path Study.

BACKGROUND: Idiopathic hypereosinophilic syndrome is characterized by a persistent eosinophil blood count of >1.5 × 109 cells/l and organ damage, independent of the primary and secondary causes of eosinophilia. The purpose of the present study was to assess the three-dimensional speckle tracking echocardiography-derived right atrial volumetric and functional properties between hypereosinophilic syndrome patients and matched controls. METHODS: A total of 11 patients with idiopathic hypereosinophilic syndrome and 22 age- and gender-matched healthy controls were enrolled in the study. Three-dimensional speckle tracking echocardiography was used for calculation of right atrial volumes, volume-based functional properties, and strain parameters. RESULTS: Significantly increased right atrial maximum (68.7 ± 33.1 ml vs. 40.3 ± 12.1 ml, respectively; p = 0.001) and minimum volumes (48.3 ± 31.0 ml vs. 28.3 ± 9.4 ml, respectively; p = 0.009), as well as right atrial volume before atrial contraction (58.6 ± 27.3 ml vs. 34.5 ± 11.8 ml, respectively; p = 0.001), were found in hypereosinophilic syndrome patients compared with controls. Total and passive right atrial stroke volumes proved to be significantly increased in hypereosinophilic syndrome patients. However, global and mean segmental strain parameters did not differ significantly between the groups. CONCLUSION: Increased cyclic right atrial volumes and mild alterations in right atrial functional properties could be demonstrated in idiopathic hypereosinophilic syndrome patients.

Left ventricular rotational mechanics differ between lipedema and lymphedema: Insights from the three-dimensional speckle tracking echocardiographic MAGYAR-path study.

The present study aimed to assess LV rotational mechanics by three-dimensional speckle-tracking echocardiography (3DSTE) in lipedema (n=25), lymphedema (n=26) patient groups with age- and gender-matched healthy controls (n=54). 3 lipedema and 4 lymphedema patients were excluded due to insufficient image quality for 3DSTE analysis. LV apical rotation (9.61 ± 4.25 degree vs. 6.40 ± 2.63 degree, p <0.05) and LV twist (13.83 ± 4.89 degree vs. 10.04 ± 3.56 degree, p <0.05) are impaired in lipedema patients as compared to matched controls; similar alterations in lymphedema were not found. Moreover, in some lipedema and lymphedema patients severe LV rotational abnormalities could be detected. Our results suggest that lipedema-associated impaired LV apical rotation and twist assessed by 3DSTE could be a novel differential diagnostic point between lipedema and lymphedema.

Current-Phase Relation of Ballistic Graphene Josephson Junctions.

The current-phase relation (CPR) of a Josephson junction (JJ) determines how the supercurrent evolves with the superconducting phase difference across the junction. Knowledge of the CPR is essential in order to understand the response of a JJ to various external parameters. Despite the rising interest in ultraclean encapsulated graphene JJs, the CPR of such junctions remains unknown. Here, we use a fully gate-tunable graphene superconducting quantum intereference device (SQUID) to determine the CPR of ballistic graphene JJs. Each of the two JJs in the SQUID is made with graphene encapsulated in hexagonal boron nitride. By independently controlling the critical current of the JJs, we can operate the SQUID either in a symmetric or asymmetric configuration. The highly asymmetric SQUID allows us to phase-bias one of the JJs and thereby directly obtain its CPR. The CPR is found to be skewed, deviating significantly from a sinusoidal form. The skewness can be tuned with the gate voltage and oscillates in antiphase with Fabry-Pérot resistance oscillations of the ballistic graphene cavity. We compare our experiments with tight-binding calculations that include realistic graphene-superconductor interfaces and find a good qualitative agreement.

Sub-100-nm negative bend resistance ballistic sensors for high spatial resolution magnetic field detection.

We report the magnetic field detection properties of ballistic sensors utilizing the negative bend resistance of InSb∕In(1-x)Al(x)Sb quantum well cross junctions as a function of temperature and geometric size. We demonstrate that the maximum responsivity to magnetic field and its linearity increase as the critical device dimension is reduced. This observation deviates from the predictions of the classical billiard ball model unless significant diffuse boundary scattering is included. The smallest device studied has an active sensor area of 35×35 nm(2), with a maximum responsivity of 20 kΩ∕T, and a noise-equivalent field of 0.87µT∕Hz at 100 K.

Room temperature ballistic transport in InSb quantum well nanodevices.

We report the room temperature observation of significant ballistic electron transport in shallow etched four-terminal mesoscopic devices fabricated on an InSb/AlInSb quantum well (QW) heterostructure with a crucial partitioned growth-buffer scheme. Ballistic electron transport is evidenced by a negative bend resistance signature which is quite clearly observed at 295 K and at current densities in excess of 10(6) A/cm(2). This demonstrates unequivocally that by using effective growth and processing strategies, room temperature ballistic effects can be exploited in InSb/AlInSb QWs at practical device dimensions.

Quantum-classical correspondence in the wave functions of andreev billiards.

We present a classical and quantum mechanical study of an Andreev billiard with a chaotic normal dot. We demonstrate that the nonexact velocity reversal and the diffraction at the edges of the normal-superconductor contact render the classical dynamics of these systems mixed indicating the limitations of a widely used retracing approximation. We point out the close relation between the mixed classical phase space and the properties of the quantum states of Andreev billiards, including periodic orbit scarring and localization of the wave function onto other classical phase space objects such as intermittent regions and quantized tori.

Proximity-induced subgaps in andreev billiards.

We examine the density of states of an Andreev billiard and show that any billiard with a finite upper cutoff in the path length distribution P(s) will possess an energy gap on the scale of the Thouless energy. An exact quantum mechanical calculation for different Andreev billiards gives good agreement with the semiclassical predictions when the energy dependent phase shift for Andreev reflections is properly taken into account. Based on this new semiclassical Bohr-Sommerfeld approximation of the density of states, we derive a simple formula for the energy gap. We show that the energy gap, in units of Thouless energy, may exceed the value predicted earlier from random matrix theory for chaotic billiards.