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Every year, injuries associated with fall incidences cause lots of human suffering and assets loss for Parkinson’s disease (PD) patients. Thereinto, freezing of gait (FOG), which is one of the most common symptoms of PD, is quite responsible for most incidents. Although lots of researches have been done on characterized analysis and detection methods of FOG, large room for improvement still exists in the high accuracy and high efficiency examination of FOG. In view of the above requirements, this paper presents a template-matching-based improved subsequence Dynamic Time Warping (IsDTW) method, and experimental tests were carried out on typical open source datasets. Results show that, compared with traditional template-matching and statistical learning methods, proposed IsDTW not only embodies higher experimental accuracy (92%) but also has a significant runtime efficiency. By contrast, IsDTW is far more available in real-time practice applications. [ABSTRACT FROM AUTHOR]

Temperature-dependent ac current-voltage-capacitance characteristics between 90 K and 440 K were investigated for InGaN/GaN multi-quantum-wells blue light-emitting diodes (LEDs) under high forward bias. Under large forward current, deep saturation of junction voltage Vj was observed over a wide temperature range. It was found that Vj corresponds to the separation energy of electron and hole quasi-Fermi levels and its temperature dependence could be well explained by the flat band model. After the pinning of quasi-Fermi levels, the forward current is dominated by the drift current in the p -GaN access layer. Considering Poole-Frenkel effect, a quantitative model was developed to reproduce the cur-rent-voltage characteristics of LEDs under high forward bias. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We report the stimulated emission related anomalous behavior of electrical parameters in GaN-based laser diodes based on both experiments and self-consistent calculations. In particular, the separation of quasi-Fermi levels of electrons and holes across active region shows a drop (or 'pinning') in threshold region, followed by an increase with current. The start and end points correspond to the two kink points of the first derivative of the optical output power-current (P-I) curve. This abnormal change of electrical parameters always satisfies the need of sufficient carriers for stimulated emission in the process of transition to lasing as well as lasing enhancement. [ABSTRACT FROM AUTHOR]

detailed study is presented on magnetic, electrical and optical properties of GaMnN: Si film grown by metal organic chemical vapor deposition (MOCVD) with high-purity SiH as the Si dopant source. The room-temperature field dependence magnetization and zero-field-cooled (ZFC)/field-cooled (FC) measurements indicate that the film remains room-temperature ferromagnetism and it declines slightly after Si co-doping. However, room-temperature Hall measurements indicate that the electrical property of the film improves distinctly compared with GaMnN. Cathode luminescence (CL) measurements show an obvious enhancement in luminous property and different peak strength changes at three different positions. Therefore, we demonstrate that Fermi level and the electron structure of Mn atoms will change with variation of the impurities co-doped and the intrinsic defects and this may be related with room-temperature ferromagnetism and the other corresponding properties of the film. [ABSTRACT FROM AUTHOR]

AlN layer was grown as interlayer between undoped GaN and Mg doped Al0.14Ga0.86N/GaN superlattices (SLs) epilayer to modulate the strain distribution between Al0.14Ga0.86N barrier and GaN well layers in SLs sample. Strain relaxation was observed in the SLs sample with AlN interlayer by x-ray diffraction reciprocal space mapping method. The measured hole concentration of SLs sample with AlN interlayer at room temperature was over 1.6×1018 cm-3 but that was only 6.6×1016 cm-3 obtained in SLs sample without AlN interlayer. Variable temperature Hall-effect measurement showed that the acceptor activation energy decreased from 150 to 70 meV after inserting the AlN layer, which indicated that the strain modulation of SLs induced by AlN interlayer was beneficial to the Mg acceptor activation and hole concentration enhancement. [ABSTRACT FROM AUTHOR]

The problem of weak magnetism has hindered the application of magnetic semiconductors since their invention, and on the other hand, the magnetic mechanism of GaN-based magnetic semiconductors has been the focus of long-standing debate. In this work, nanoscale GaN:Mn wires were grown on the top of GaN ridges by metalorganic chemical vapor deposition (MOCVD), and the superconducting quantum interference device (SQUID) magnetometer shows that its ferromagnetism is greatly enhanced. Secondary ion mass spectrometry (SIMS) and energy dispersive spectroscopy (EDS) reveal an obvious increase of Mn composition in the nanowire part, and transmission electron microscopy (TEM) and EDS mapping results further indicate the correlation between the abundant stacking faults (SFs) and high Mn doping. When further combined with the micro-Raman results, the magnetism in GaN:Mn might be related not only to Mn concentration, but also to some kinds of built-in defects introduced together with the Mn doping or the SFs., Competing Interests: The authors declare no conflict of interest.

We identify that the stimulated emission of GaN laser diodes (LDs) emerges far below the traditionally recognized threshold from both optical and electrical experiments. Below the threshold, the linear-polarized stimulated emission has been the dominating part of overall emission and closely related to resonant cavity. Its intensity increases super linearly with current while that of spontaneous emission increases almost linearly. Moreover, the separation of quasi-Fermi levels of electrons and holes across the active region has already exceeded the photon emission energy, namely, realized the population-inversion.