X-ray diffraction study of the CDW phase in (TaSe4)2I: Determination of the CDW modulation amplitude

An extensive X-ray diffraction study of charge density wave (CDW) phase in (TaSe₄)₂I is reported. We have observed the superstructure satellites at 2q in addition to those at q reported by Fujishita et al. The results imply a sinusoidal lattice modulation with polarization almost perpendicular to q (i.e. transverse) and the existence of CDW domains. At 15 K we have extracted an approximate value for the amplitude of the lattice modulation perpendicular to q to be μ_⊥ ∽ 0.087 Å.     

Episodic paroxysmal laryngospasm: Voice and pulmonary function assessment and management

Episodic paroxysmal laryngospasm (EPL) is a sign of laryngeal dysfunction, often without a specific organic etiology, which can masquerade as asthma, vocal fold paralysis, or a functional voice disorder. The intermittent respiratory distress of EPL may precipitate an apparent upper airway obstructive emergency, resulting in unnecessary endotracheal intubation, cardiopulmonary resuscitation, or tracheostomy. During 27 months, seven women and three men, ages 30–76 years, were assessed by a high diagnostic index of suspicion, an intensive history including psychosocial factors, physical examination of the airways, provocative asthma testing, and swallowing studies. Videolaryngoscopy, stroboscopy, and pulmonary flow-volume loop testing were definitive. The classic appearance was paradoxic inspiratory adduction of the anterior vocal folds with a posterior diamond-shaped glottic gap. During an attack of stridor or wheezing, attenuation of the inspiratory flow rate as depicted by the flow-volume loop suggested partial extrathoracic upper airway obstruction. Swallowing evaluation by videolaryngoscopy and videoesophagography may uncover gastroesophageal reflux disease. Hallmarks of management include patient and family education by observation of laryngoscopic videos, a specific speech therapy program, psychotherapy, and medical treatment of associated disorders. Electromyography may become a valuable future adjunct. Unlike laryngeal dystonia, patients with EPL do not benefit from botulinum toxin type A.     

Frequency dependence of phase-synchronization time in nonlinear dynamical systems

It has been found recently that the averaged phase-synchronization time between the input and the output signals of a nonlinear dynamical system can exhibit an extremely high sensitivity to variations in the noise level. In real-world signal-processing applications, sensitivity to frequency variations may be of considerable interest. Here we investigate the dependence of the averaged phase-synchronization time on frequency of the input signal. Our finding is that, for typical nonlinear oscillator systems, there can be a frequency regime where the time exhibits significant sensitivity to frequency variations. We obtain an analytic formula to quantify the frequency dependence, provide numerical support, and present experimental evidence from a simple nonlinear circuit system.     

Spin-orbit interaction in symmetric wells with two subbands

We investigate the spin-orbit (SO) interaction in two-dimensional electron gases in quantum wells with two subbands. From the 8x8 Kane model, we derive a new intersubband-induced SO term which resembles the functional form of the Rashba SO but is nonzero even in symmetric structures. This follows from the distinct parity of the confined states (even or odd) which obliterates the need for asymmetric potentials. We self-consistently calculate the new SO coupling strength for realistic wells and find it comparable to the usual Rashba constant. Our new SO term gives rise to a nonzero ballistic spin-Hall conductivity, which changes sign as a function of the Fermi energy (epsilonF) and can induce an unusual Zitterbewegung with cycloidal trajectories without magnetic fields.     

Gyrocenter shift of low-temperature plasmas and the retrograde motion of cathode spots in arc discharges

The gyrocenter shift phenomenon explained the mechanism of radial electric field formation at the high confinement mode transition in fusion devices. This Letter reports that the theory of gyrocenter shift is also applicable to low temperature high collisional plasmas such as arc discharges by the generalization of the theory resulting from a short mean free path compared with the gyroradius. The retrograde motion of cathode spots in the arc discharge is investigated through a model with the expanded formula of gyrocenter shift. It is found that a reversed electric field is formed in front of the cathode spots when they are under a magnetic field, and this reversed electric field generates a rotation of cathode spots opposite to the Amperian direction. The ion drift velocity profiles calculated from the model are in agreement with the experimental results as functions of magnetic flux density and gas pressure.     

Edge-soliton-mediated vortex-core reversal dynamics

We report an additional reversal mechanism of magnetic vortex cores in nanodot elements driven by currents flowing perpendicular to the sample plane, occurring via dynamic transformations between two coupled edge solitons and bulk vortex solitons. This mechanism differs completely from the well-known switching process mediated by the creation and annihilation of vortex-antivortex pairs in terms of the associated topological solitons, energies, and spin-wave emissions. Strongly localized out-of-plane gyrotropic fields induced by the fast motion of the coupled edge solitons enable a magnetization dip that plays a crucial role in the formation of the reversed core magnetization. This work provides a deeper physical insight into the dynamic transformations of magnetic topological solitons in nanoelements.     

Fabrication of microstructures on paraffin substrate using laser heating

In this paper, a technique of forming convex microstructures on a paraffin substrate using laser heating is described. This technique makes use of a phenomenon that solid paraffin, melted by continuous laser irradiation, grows into a pillar-shaped structure with a high aspect ratio in a liquid. Two-dimensional structures, such as line- and wall-shaped structures, are available by scanning irradiation. Also, it is possible to fabricate oblique structures with an inclined laser irradiation. In addition, some characteristics of this fabrication method, such as the laser power and the material temperature, are investigated. Furthermore, the mechanism of this fabrication method is presented. PACS 07.10.Cm; 47.55.Pf; 65.40.De; 79.20.Ds; 81.05.-t     

Erratum to Formation and control of Au and Ag nanoparticles inside borate glasses using femtosecond laser and heat treatment

We report the spectroscopic properties of femtosecond laser-irradiated sodium-alumino-borate glass doped with silver and gold ions. We precipitated gold and silver nanoparticles by laser irradiation and annealing at 400°C for 30 min. The irradiation and annealing treatment produced different absorption and emission characteristics in Au³⁺ doped and Au³⁺, Ag⁺ codoped glasses, and the possible mechanisms of the observed results are discussed. The size of the nanoparticles was estimated by TEM and absorption band analysis.     

Josephson effect through an isotropic magnetic molecule

We study the Josephson effect through a quantum dot magnet whose spin is isotropic and which is coupled to the dot electron spin via exchange coupling. We calculate the Andreev levels and the supercurrent and examine the intertwined effect of the exchange coupling, Kondo correlation, and superconductivity. The former suppresses Kondo correlations, which triggers phase transitions from the 0 to the pi state, but strong antiferromagnetic coupling restores the 0 state. The asymmetric phase diagram in the exchange coupling suggests that the coupling sign could be determined in experiments.     

Angle-independent and multi-dimensional myocardial elastography--from theory to clinical validation

The angle-independent myocardial elastography, which shows good performance in our proposed theoretical framework using a three-dimensional, ultrasonic image formation model based on well-established, 3D finite-element, canine, left-ventricular models in both normal and left-circumflex ischemic cases, is employed as well as validated in vivo to assess the contractility of normal and pathological myocardia. Angle-independent myocardial elastography consists of: (1) iterative estimation of in-plane and out-of-plane cumulative displacements during systole using 1D cross-correlation and recorrelation techniques in a 2D search; (2) calculation of in-plane finite strains from the in-plane cumulative motion; and (3) computation of in-plane principal strains from the finite strains by eigen decomposition with a classification strategy. The in vivo raw data of healthy and pathological human left ventricles were acquired at 136 fps in a short-axis echocardiographic view. Similar to theory, the elastographic estimates in normal clinical cases showed radial wall thickening and circumferential shortening during systole through principal strain imaging, while those in a pathological case underwent opposite strains. The feasibility of angle-independent myocardial elastography with an automated contour tracking method was hereby demonstrated through imaging of the myocardial deformation, and principal strains were proven essential in the reliable characterization and differentiation of abnormal from normal myocardia, without any angular dependence.