Two-dimensional microcavity lasers Harayama, T.; Shinohara, S.
Laser & photonics reviews,
March 2011, Volume:
5, Issue:
2
Journal Article
Peer reviewed
Advances in processing technology, such as quantum‐well structures and dry‐etching techniques, have made it possible to create new types of two‐dimensional (2D) microcavity lasers which have 2D ...emission patterns of output laser light although conventional one‐dimensional (1D) edge‐emitting‐type lasers have 1D emission. Two‐dimensional microcavity lasers have given nice experimental stages for fundamental researches on wave chaos closely related to quantum chaos. New types of 2D microcavity lasers also can offer the important lasing characteristics of directionality and high‐power output light, and they may well find applications in optical communications, integrated optical circuits, and optical sensors. Fundamental physics of 2D microcavity lasers has been reviewed from the viewpoint of classical and quantum chaos, and recently developed theoretical approaches have been introduced. In addition, nonlinear dynamics due to the interaction among wave‐chaotic modes through the active lasing medium is explained. Applications of 2D microcavity lasers for directional emission with strong light confinement are introduced, as well as high‐precision rotation sensors designed by using wave‐chaotic properties.
Advances in processing technology, such as quantum‐well structures and dry‐etching techniques, have made it possible to create new types of two‐dimensional (2D) microcavity lasers which have 2D emission patterns of output laser light. Two‐dimensional microcavity lasers have given nice experimental stages for fundamental researches on wave chaos closely related to quantum chaos. New types of 2D microcavity lasers also can offer the important lasing characteristics of directionality and high‐power output light, and they may well find applications in optical communications, integrated optical circuits, and optical sensors.
Purpose
To define the bony attachments of the medial ligaments relative to anatomical and radiographic bony landmarks, providing information for medial collateral ligament (MCL) surgery.
Method
The ...femoral and tibial attachments of the superficial MCL (sMCL), deep MCL (dMCL) and posterior oblique ligament (POL), plus the medial epicondyle (ME) were defined by radiopaque staples in 22 knees. These were measured radiographically and optically; the precision was calculated and data normalised to the sizes of the condyles. Femoral locations were referenced to the ME and to Blumensaat’s line and the posterior cortex.
Results
The femoral sMCL attachment enveloped the ME, centred 1 mm proximal to it, at 37 ± 2 mm (normalised at 53 ± 2%) posterior to the most-anterior condyle border. The femoral dMCL attachment was 6 mm (8%) distal and 5 mm (7%) posterior to the ME. The femoral POL attachment was 4 mm (5%) proximal and 11 mm (15%) posterior to the ME. The tibial sMCL attachment spread from 42 to 71 mm (81–137% of A-P plateau width) below the tibial plateau. The dMCL fanned out anterodistally to a wide tibial attachment 8 mm below the plateau and between 17 and 39 mm (33–76%) A-P. The POL attached 5 mm below the plateau, posterior to the dMCL. The 95% CI intra-observer was ± 0.6 mm, inter-observer ± 1.3 mm for digitisation. The inter-observer ICC for radiographs was 0.922.
Conclusion
The bone attachments of the medial knee ligaments are located in relation to knee dimensions and osseous landmarks. These data facilitate repairs and reconstructions that can restore physiological laxity and stability patterns across the arc of knee flexion.
The combination of hot-wire insertion technology and gas metal arc welding (GMAW) is proposed to enhance the deposition rates while reducing energy consumption. This study systematically investigated ...the effect of hot-wire fraction on weld metal properties. The results reveal that the compensatory deposition rate from hot-wire insertion provides a similar effective height compared with conventional GMAW, with a lower weld height/width ratio, lower power consumption, and improved mechanical properties. However, an excessive hot-wire fraction may lead to lack of fusion, and this value should be limited to no more than 44% of the total deposition rate. By strategically optimizing the ratios of GMAW and hot-wire fractions, it becomes possible to maximize deposition volume while preventing fusion deficiencies and ensuring adequate penetration. Under these optimized conditions, hot-wire GMAW proves to be an efficient method for achieving equivalent deposition rates with reduced energy consumption and without compromising toughness properties. An electron backscattering diffraction (EBSD) analysis underscores the effectiveness of the proposed approach, particularly when utilizing a 41.16% hot-wire fraction, ensuring both sound joint formation and the predominance of an acicular ferrite microstructure, thereby enhancing mechanical properties. This innovative process presents a sustainable alternative to conventional GMAW, offering substantial benefits of welding technology.
Background
Approximately 40% of patients with chronic low back pain have a neuropathic component. In this study, we assessed the effects of analgesics on tactile hypersensitivity and walking distance ...in the rat cauda equina compression (CEC) model of neuropathic low back pain.
Methods
The effects of analgesics on tactile hypersensitivity were examined using the von Frey test in CEC and partial sciatic nerve ligation (pSNL) models. Effects on walking distance were assessed using a treadmill test. Levels of α2δ1 subunit and ATF‐3 mRNA in dorsal‐root ganglion (DRG) neurons and those of α2δ1 subunit protein in the spinal cord were determined using quantitative RT‐PCR and western blotting, respectively. Histological features were assessed using immunohistological methods.
Results
Histological changes indicating nerve damage (increase in ATF‐3 mRNA, decrease in NF‐200 and an increase in CD68 immunoreactivity) were observed in the CEC model. Duloxetine had analgesic effects in both models and improved walking distance in the CEC model. Pregabalin had analgesic effects in both models; however, the effect was weaker in the CEC model than in the pSNL model. α2δ1 subunit expression in DRG neurons and in the spinal cord was unchanged in the CEC model, but significantly increased in the pSNL model. Indomethacin had no analgesic effect in either model. Intrathecal yohimbine inhibited the effects of duloxetine with significant effects on depression.
Conclusions
These findings suggest that the analgesic effects of duloxetine are mainly mediated by the spinal monoamine system, independent of the antidepressant effects of this agent.
Significance
The findings of this study suggest that duloxetine may be an effective treatment of broad neuropathic pain states, including neuropathic low back pain. The analgesic effects of duloxetine might be mediated by alterations of the descending pain modulatory pathways in the spinal cord, independent of the antidepressant effects.
It is crucial to measure the electron density (ne) and temperature (Te) for applications such as developing small helicon sources in plasma thrusters. Hence, this study developed a method based on an ...optical emission spectroscopic (OES) measurement without disturbance or contamination for helicon plasma produced using argon gas. The argon collisional-radiative (CR) model was used to describe the excitation number density in plasma as a function of ne and Te. Each number density ratio was surveyed as a function of ne and Te. From these results, contours of two number densities, i.e., two excitation energy levels, were drawn on an ne–Te plane. By applying various contour pairs, ne and Te were determined from the intersection point of two contours whose values were taken from the experimental intensities. Finally, we compared the new OES measurements with the CR model for various intensity ratios and found a way to select a valid intensity ratio that is in good agreement with the ne and Te derived by the probe method.
The purpose of this study was to optimize the conditions of the gas–metal arc welding using CO
2
shield gas (CO
2
arc welding) with hot-wire feeding technology. A high-speed camera was used to ...investigate welding phenomena of a butt joint of 36-mm-thick steel plates. The optimum parameters were determined under combinations of the welding current (300 or 400 A) and hot-wire feeding speed (0 to 12.5 m/min) to avoid molten metal precedence. A sound joint was achieved with only four weld passes using optimum conditions. Adequate joint properties, including tensile strength and toughness, were obtained. The optimum conditions provided a welding process with both high efficiency and low heat input.
Biomodification of existing hard tissue structures, specifically tooth dentin, is an innovative approach proposed to improve the biomechanical and biochemical properties of tissue for potential ...preventive or reparative therapies. The objectives of the study were to systematically characterize dentin matrices biomodified by proanthocyanidin-rich grape seed extract (GSE) and glutaraldehyde (GD). Changes to the biochemistry and biomechanical properties were assessed by several assays to investigate the degree of interaction, biodegradation rates, proteoglycan interaction, and effect of collagen fibril orientation and environmental conditions on the tensile properties. The highest degree of agent-dentin interaction was observed with GSE, which exhibited the highest denaturation temperature, regardless of the agent concentration. Biodegradation rates decreased remarkably following biomodification of dentin matrices after 24h collagenase digestion. A significant decrease in the proteoglycan content of GSE-treated samples was observed using a micro-assay for glycosaminoglycans and histological electron microscopy, while no changes were observed for GD and the control. The tensile strength properties of GD-biomodified dentin matrices were affected by dentin tubule orientation, most likely due to the orientation of the collagen fibrils. Higher and/or increased stability of the tensile properties of GD- and GSE-treated samples were observed following exposure to collagenase and 8 months water storage. Biomodification of dentin matrices using chemical agents not only affects the collagen biochemistry, but also involves interaction with proteoglycans. Tissue biomodifiers interact differently with dentin matrices and may provide the tissue with enhanced preventive and restorative/reparative abilities.
We have proposed Rotating Magnetic Field (RMF) acceleration method as one of
electrodeless plasma accelerations. In our experimental scheme, plasma generated by an rf
(radio frequency) antenna, is ...accelerated by RMF antennas, which consist of two-pair,
opposed, facing coils, and these antennas are outside of a discharge tube. Therefore,
there is no wear of electrodes, degrading the propulsion performance. Here, we will
introduce our RMF acceleration system developed, including the experimental device, e.g.,
external antennas, a tapered quartz tube, a vacuum chamber, external magnets, and a
pumping system. In addition, we can change RMF operation parameters (RMF applied current
I
RMF and RMF current phase difference ϕ,
focusing on RMF current frequency f
RMF) by adjusting matching
conditions of RMF, and investigate the dependencies on plasma parameters (electron density
n
e and ion velocity v
i); e.g.,
higher increases of n
e and v
i
(∼360 % and 55 %, respectively) than previous experimental results were obtained by
decreasing f
RMF from 5 MHz to 0.7 MHz, whose RMF penetration
condition was better according to Milroy’s expression. Moreover, time-varying component of
RMF has been measured directly to survey the penetration condition experimentally.
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