Carrier Transport and Optical Properties of InGaN SQW With Embedded AlGaN$delta$-Layer

We investigate the carrier transport and optical properties of a thick InGaN single quantum well (SQW) where an AlGaN delta-layer is embedded. By way of simulation, it is found that the carrier density distribution in the active region is more uniform in such a QW structure, compared to a double QW (DQW) configuration showing a discontinuity in the hole quasi-Fermi level due to the large effective mass of the holes along with the strong piezoelectric field. Through the photoluminescence (PL) measurements, we have shown that the PL peak energy varies depending sensitively on the delta-layer thickness, providing an extra degree of freedom in the wavelength-tuning control. In particular, such a QW structure is highly desired for long-wavelength emission as the wavelength tuning can be achieved with lower indium composition. The embedded delta-layer also increases the wave function overlap between holes and electrons, thereby shortening the PL lifetime. The results of PL measurements are shown to be consistent with the self-consistent numerical results. A possible application of the proposed QW structure is to the design of long-wavelength light-emitting diodes and laser diodes     

Measurement of specific movement power application: evaluation of weight lifters

A new dynamometer was developed for the measurement of specific movement power (SMP) exerted by mono- or multi-articular movements. To determine the reproducibility of SMP, two identical test protocols were carried out on separate days for six movement types on seven adult males. The movement types were arm pull (AP), leg rise (LR), knee extension (KE), elbow flexion (EF), hip extension (HE) and squat movement (SQ). Variations in peak power obtained in two tests ranged from 0.7% (AP) to 9.6% (SQ). Coefficients of the test-re-test correlation in peak power ranged from 0.805 (SQ) to 0.961 (AP) and standard errors ranged from 4 W (EF) to 14 W (SQ). SMP in upper extremities increased from 166 W (EF) to 307 W (AP) resulting from the increase in velocity. However, in the movements of lower extremities, SMP increased from 506 W (KE) to 1351 W (SQ) as a result of the increase in force. To evaluate the validity of the SMP, a pull movement in weightlifting was tested and related to the athletic performance on weightlifters. Positive linear correlation (r = 0.862, p<0.001) was observed between SMP and the total weight best records. It is concluded that this newly developed dynamometer has enough reproducibility and validity for evaluating the SMP, which is developed by various joint movement patterns related to the sport. The feasibility of applying this measuring protocol to the testing and training programmes for improving the daily living activities and athletic performances should now be assessed.     

Transient power characteristics of balanced three‐phase variable inductance

Inductance has a particularly important role in power circuits. The authors have proposed the Variable Active–Passive Reactance (VAPAR), which can produce a virtual variable inductance. In this paper, the transient power characteristics of a balanced three‐phase variable inductance are analyzed using the instantaneous active and reactive power theorem. With an ideal voltage source or an ideal current source connected to a balanced three‐phase variable inductance, the transient power characteristics are analyzed theoretically, and then the results are verified through simulations. In the other cases, it is difficult to solve for the transient power, but it is shown that the transient power characteristics can easily be estimated from the results of simulations in which an ideal voltage source or an ideal current source is connected to a balanced three‐phase variable inductance. Experiments are also carried out to verify the theoretical analysis and simulations. © 2001 Scripta Technica, Electr Eng Jpn, 136(2): 49–57, 2001     

Active-passive power circuit

The recent development of a semiconductor device technology realizes small-size, lightweight, high performance power switching devices. However, reactive elements such as an inductor or a PWM inverter achieves high-performance current control, which is applied to the active filter, and so on [2, 4]. If a compact and high efficient reactive component is developed, the power converter technology may drastically change the application field. In this paper, the concept of variable active-passive reactance (VAPAR) which consists of an inverter and passive elements is proposed. The VAPAR behaves like a two-terminal reactive element and the produced active reactance component works as a passive reactive component, including in transient state. The principle of VAPAR and two possible control schemes to realize VAPAR are realized. Through simulations and experiments, it is verified that VAPAR shows reactive characteristics not only in steady state, but also in transient state, as proposed, and basic characteristics of both control schemes are clarified.     

Astrocytes containing amyloid beta-protein (Abeta)-positive granules are associated with Abeta40-positive diffuse plaques in the aged human brain

Amyloid beta-protein (Abeta) is the major component of senile plaques that emerge in the cortex during aging and appear most abundantly in Alzheimer's disease. In the course of our immunocytochemical study on a large number of autopsy cases, we noticed, in many aged nondemented cases, the presence of unique diffuse plaques in the cortex distinct from ordinary diffuse plaques by immunocytochemistry. The former were amorphous, very faintly Abeta-immunoreactive plaques resembling diffuse plaques, but they stained for Abeta40 and were associated with small cells containing Abeta-positive granules. A panel of amino- and carboxyl-terminal-specific Abeta antibodies showed that such Abeta40-positive diffuse plaques and cell-associated granules were composed exclusively of amino-terminally deleted Abeta terminating at Abeta40, -42, and -43. Double immunostaining also showed that those Abeta-immunoreactive granules are located in astrocytes and not in microglia or neurons. Immunoelectron microscopy revealed that nonfibrillar Abeta immunoreactivity was located within lipofuscin-like granules in somewhat swollen astrocytes. These findings raise the possibility that astrocytes take up Abeta and attempt to degrade it in lysosomes in the aged brain.     

Instrumentation for dual-probe scanning near-field optical microscopy

To investigate local carrier motions, we developed a dual-probe scanning near-field optical microscope (SNOM) with two fiber probes where one is for photoexcitation and the other is for light collection. This instrumentation is based on two important techniques: the design of probe structures and distance control between the sample surface and the two probes. A finite-difference time-domain method numerically analyzed and optimized the design for high efficiency photoexcitation and light collection, while a dual band modulation realized distance control. Real time detection of the oscillations of the probe tips using different frequencies independently controls the distance between the probe tip and the sample surface as well as the distance between the two probes. Thus, the collection probe can be scanned around an illumination probe without destroying the probe tips. To demonstrate our SNOM, we performed photoluminescence spectroscopy under the dual-probe configuration and observed carrier motions in an InGaN quantum well.     

Complementation analysis reveals a potential role of human ARV1 in GPI anchor biosynthesis

ARV1 is involved in regulating lipid homeostasis but also in the biosynthesis of glycosylphosphatidylinositol (GPI) in Saccharomyces cerevisiae. Here, we examined whether human ARV1 can complement the role of yeast ARV1 in GPI biosynthesis. Overexpression of human ARV1 could rescue the phenotypes associated with GPI anchor synthesis defect in the yeast arv1Δ mutant. The results suggest that Arv1 function in GPI biosynthesis may be conserved in all eukaryotes, from yeast to humans. Copyright © 2015 John Wiley & Sons, Ltd.