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Abstract: We report the effect due to a simultaneous excitation of several exciton states on the radiative decay profiles on the basis of the nonlocal response of weakly confined excitons in GaAs thin films. In the case of excitation of single exciton state, the transient grating signal has two decay components. The fast decay component comes from nonlocal response, and the long-lived component is attributed to free exciton decay. With an increase of excitation spectral width, the nonlocal component becomes small in comparison with the long-lived component, and disappears under irradiation of a femtosecond-pulse laser with broader spectral width. The transient grating spectra clearly indicates the contribution of the weakly confined excitons to the signal, and the exciton line width hardly changes by excitation spectral width. From these results, we concluded that the change of decay profile is attributed not to the many-body effect but to the effect of simultaneous excitation of several exciton states. [Copyright &y& Elsevier]

Abstract: We report the dynamical properties of the exciton orientation in GaAs thin films using the orientational grating (OG) technique. From the results of excitation-power dependence of OG signal, we confirmed that the OG signal comes from the optical nonlinearity of weakly confined excitons. In addition, the OG-decay time decreases with an increase of excitation power due to exciton–exciton interaction, and the shortest decay time is below 1ps. Our results may imply the potential application of optical nonlinearity of weakly confined exciton to ultrafast switching devices operating at 1Tbit/s. [Copyright &y& Elsevier]

We report a patient with bow hunter’s syndrome who was treated by anterior decompression of the vertebral artery (VA) using an ultrasonic bone curette (SONOPET). This 60-year-old man reported almost losing consciousness upon head rotation. Although the right VA appeared normal at the natural head position, upon left head rotation it became completely occluded at the transverse foramen of C2. We performed anterior decompression of the right VA at the axis using a high-speed drill and SONOPET. For anterior decompression of the VA in a deep and narrow operative field, we recommend use of SONOPET, which permits safe, easy bone dissection. [ABSTRACT FROM AUTHOR]

Microscopic distribution of growth rates on mesa-etched GaAs(001) wafers was measured in real time during molecular beam epitaxy growth by scanning microprobe reflection high-energy electron diffraction. It has been observed that the growth rate on the GaAs(001) surface near the edge of (111)A surfaces becomes larger. The exponential variation of the growth rate as a function of the distance from the edge reflects surface diffusion of Ga atoms. The diffusion length on the (001) surface is estimated to be about 1 μm at 560 °C. The relatively larger diffusion length suggests that the incorporation rate of migrating Ga atoms by steps is much smaller than unity. [ABSTRACT FROM AUTHOR]

Focuses on a study that investigated gallium arsenide[subl] and aluminum arsenide[subm] superlattices by photoluminescence excitation. Details of the experiment; Calculations; Conclusions.

The article presents a case study of ligamentum flavum (LF) hemorrhage in the lumbar spine. The case was taken from a 67-year-old man who experienced pains in his left leg four weeks after an accident. The patient underwent magnetic resonance imaging and it was discovered that the limbar canal stenosis and the left LF at L4 to L5 was expanded a little and has abnormal intensities. Prognosis was done under laminectomy and excision of the LF and revealed a good result.

Investigates the characterization of zinc selenide (ZnSe) epitaxial layer reactive-ion-etched by a gas mixture of ethane and hydrogen. Measurement of the sheet resistance of ZnSe epitaxial layers; Details on the estimated electrically active thicknesses; Importance of reactive ion etching for the fabrication of compound semiconductor devices.

Self-assembled InAs quantum dots (QDs), without and with an AlAs cap, were grown on (311)B GaAs substrates by molecular beam epitaxy. Surface morphologies of QDs were characterized by atomic force microscopy. Photoluminescence (PL) was performed in the 4–300 K temperature range. For QDs without AlAs cap, sharp and intense PL emitted from wetting layer was observed. PL from QDs was relatively weak at 4 K. The PL intensity of QDs decreased as measurement temperature increased and was not observed at 300 K. For QDs with AlAs cap, PL from WL vanished while PL from QDs were substantially enhanced at 300 K. Suppression of PL from WL indicates that the thickness of WL was reduced due to phase separation result from AlAs cap, which is an effective way to improve the PL of InAs QDs grown on (311)B GaAs substrate. [ABSTRACT FROM AUTHOR]

Many researching efforts have been reported to seek various fundamental LC resonance structures, recently. But still the Split Ring Resonator (SRR) is the most famous and major fundamental LC-resonance structure used in the metamaterial. We employed SRR structure as the fundamental LC-resonance mechanism to fabricate photonic crystal with periodic arrangement of two different metamaterial areas composed from SRR arrays on the dielectric substrate. We developed Photonic Metamaterial Crystal (PMC) to realize the more advanced and versatile functions of the metamaterial by 1 dimensional or 2 dimensional periodic arranging of two metamaterial sections which have different dispersion properties due to the different size of SRR structures each other. In this paper, we report the fabrication process, estimation of PMC properties and some possible future application prospects, for instance the PMC waveguide structures and nonlinear properties of PMC observed as selective LC-resonant properties in Raman mapping analysis of PMC. These are quite interesting characters of PMC and the attractive applications as the PMC devices. [ABSTRACT FROM AUTHOR]

Light propagation effects on nonlinear optical response of a size-controlled GaAs thin film at exciton resonance are investigated by transient grating using picosecond pulses (1.5 ps). The signals are enhanced at the exciton resonance and the temporal profiles strongly depend on the excitation pulse energies. The result indicates that the nonlinear response is induced by excitonic polaritons and its decay is determined by the round-trip of the polariton in the film. [ABSTRACT FROM AUTHOR]