1,498 research outputs found
Effect of multilayer barriers on the optical properties of GaInNAs single quantum-well structures grown by metalorganic vapor phase epitaxy
We report on the effects of combined strain-compensating and strain-mediating layers of various widths on the optical properties of 1.3 μm GaInNAs∕GaAs single quantum well structures grown by metalorganic vapor phase epitaxy (MOVPE). While the emission wavelength of GaInNAs∕GaAs quantum wells can be redshifted by the adoption of strain-compensated GaNAs layers, the material quality is degraded by the increased stress at the well∕barrier interface. This detrimental effect can be cured by inserting a strain-mediating InGaAs layer between them. Contrary to what is expected, however, the emission wavelength is blueshifted by the insertion of the InGaAs layer, which is attributed to the reduced N incorporation due to the improved interface quality. Our results indicate that the optical properties of MOVPE-grown GaInNAs∕GaAs quantum wells can be optimized in quantum efficiency and emission wavelength by combination of strain-compensating and strain-mediating layers with suitable characteristics
Microfluidics for simultaneous quantification of platelet adhesion and blood viscosity
Platelet functions, including adhesion, activation, and aggregation have an influence on thrombosis and the progression of atherosclerosis. In the present study, a new microfluidic-based method is proposed to estimate platelet adhesion and blood viscosity simultaneously. Blood sample flows into an H-shaped microfluidic device with a peristaltic pump. Since platelet aggregation may be initiated by the compression of rotors inside the peristaltic pump, platelet aggregates may adhere to the H-shaped channel. Through correlation mapping, which visualizes decorrelation of the streaming blood flow, the area of adhered platelets (A(Platelet)) can be estimated without labeling platelets. The platelet function is estimated by determining the representative index I-A.T based on A(Platelet) and contact time. Blood viscosity is measured by monitoring the flow conditions in the one side channel of the H-shaped device. Based on the relation between interfacial width (W) and pressure ratio of sample flows to the reference, blood sample viscosity (mu) can be estimated by measuring W. Biophysical parameters (IA.T, mu) are compared for normal and diabetic rats using an ex vivo extracorporeal model. This microfluidic-based method can be used for evaluating variations in the platelet adhesion and blood viscosity of animal models with cardiovascular diseases under ex vivo conditions.119Ysciescopu
Spectroscopic characterization of 1.3µm GaInNAs quantum-well structures grown by metal-organic vapor phase epitaxy
We report optical studies of high-quality 1.3 μm strain-compensated GaInNAs/GaAs single-quantum-well structures grown by metalorganic vapor phase epitaxy. Photoluminescence excitation (PLE) spectroscopy shows clearly the electronic structure of the two-dimensional quantum well. The transition energies between quantized states of the electrons and holes are in agreement with theoretical calculations based on the band anti-crossing model in which the localized N states interact with the extended states in the conduction band. We also investigated the polarization properties of the luminescence by polarized edge-emission measurements. Luminescence bands with different polarization characters arising from the electron to heavy-hole and light-hole transitions, respectively, have been identified and verify the transition assignment observed in the PLE spectrum
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Practical application of equivalent linearization approaches to nonlinear piping systems
The use of mechanical energy absorbers as an alternative to conventional hydraulic and mechanical snubbers for piping supports has attracted a wide interest among researchers and practitioners in the nuclear industry. The basic design concept of energy absorbers (EA) is to dissipate the vibration energy of piping systems through nonlinear hysteretic actions of EA!s under design seismic loads. Therefore, some type of nonlinear analysis needs to be performed in the seismic design of piping systems with EA supports. The equivalent linearization approach (ELA) can be a practical analysis tool for this purpose, particularly when the response approach (RSA) is also incorporated in the analysis formulations. In this paper, the following ELA/RSA methods are presented and compared to each other regarding their practice and numerical accuracy: Response approach using the square root of sum of squares (SRSS) approximation (denoted RS in this paper). Classical ELA based on modal combinations and linear random vibration theory (denoted CELA in this paper). Stochastic ELA based on direct solution of response covariance matrix (denoted SELA in this paper). New algorithms to convert response spectra to the equivalent power spectral density (PSD) functions are presented for both the above CELA and SELA methods. The numerical accuracy of the three EL are studied through a parametric error analysis. Finally, the practicality of the presented analysis is demonstrated in two application examples for piping systems with EA supports
Design and Realization of Multiplexing System for Fixed/Mobile Next-Generation Broadcasting Service in Network Free Environment
The Current broadcasting enviroment is constally evolving in order to meet the various needs of the viewer such as ColorTV, 3D, HD, UHD TV serivce. And they want to broadcasting the same quality in the fixed and mobile enviroment for high definition braodcasting serive. In this paper, we presnet a design and implementation of muilplexing system for fixed/mobile next generation broadcasting service in network free enivorment. Network free means receive both the broadcasting channel and communication chennel for various TV service. We introduce method to provide next generation convergence broadcating servies based on european standard which can transmit UHD content in network free envieroment. As a result to this paper, we analyze the characteristics of the recieved signal from the commerical receiver device
Perceiving "Complex Autonomous Systems" in Symmetry Dynamics: Elementary Coordination Embedding in Circadian Cycles
This study explored the biological autonomy and control of function in circumstances that assessed the presumed relationship of an organism with an environmental cycle. An understanding of this behavior appeals to the organism–environment system rather than just the organism. Therefore, we sought to uncover the laws underlying end-directed capabilities by measuring biological characteristics (motor synchrony) in an environmental cycle (circadian temperature). We found that the typical elementary coordination (bimanual) stability measure varied significantly as a function of the day–night temperature cycle. While circadian effects under artificially manipulated temperatures were not straightforward during the day–night temperature cycle, the circadian effect divided by the ordinary circadian rhythm remained constant during the day–night cycle. Our observation of this direct, robust relationship between the biological characteristics (body temperature and motor synchrony) and environmental processes (circadian temperature cycle) could mirror the adaptation of our biological system to the environment
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Understanding seismic design criteria for Japanese nuclear power plants
This paper summarizes the results of recent survey studies on the seismic design practice for nuclear power plants in Japan. The seismic design codes and standards for both nuclear as well as non-nuclear structures have been reviewed and summarized. Some key documents for understanding Japanese seismic design criteria are also listed with brief descriptions. The paper highlights the design criteria to determine the seismic demand and component capacity in comparison with US criteria, the background studies which have led to the current Japanese design criteria, and a survey of current research activities. More detailed technical descriptions are presented on the development of Japanese shear wall equations, design requirements for containment structures, and ductility requirements
Implantation of bone marrow-derived buffy coat can supplement bone marrow stimulation for articular cartilage repair
SummaryObjectiveBone marrow stimulation (BMS) has been regarded as a first line procedure for repair of articular cartilage. However, repaired cartilage from BMS is known to be unlike that of hyaline cartilage and its inner endurance is not guaranteed. The reason presumably came from a shortage of cartilage-forming cells in blood clots derived by BMS. In order to increase repairable cellularity, the feasibility of autologous bone marrow-derived buffy coat transplantation in repair of large full-thickness cartilage defects was investigated in this study.MethodsRabbits were divided into four groups: the defect remained untreated as a negative control; performance of BMS only (BMS group); BMS followed by supplementation of autologous bone marrow buffy coat (Buffy coat group); transplantation of autologous osteochondral transplantation (AOTS) as a positive control.ResultsRepair of cartilage defects in the Buffy coat group in a rabbit model was more effective than BMS alone and similar to AOTS. Gross findings, histological analysis, histological scoring, immunohistochemistry, and chemical assay demonstrated that supplementation of autologous bone marrow buffy coat after BMS arthroplasty effectively repaired cartilage defects in a rabbit model, and was more effective than BMS arthroplasty alone.ConclusionSupplementation of autologous bone marrow-derived buffy coat in cases of BMS could be a useful clinical protocol for cartilage repair
Changes in neuropsychological functioning following temporal lobectomy in patients with temporal lobe epilepsy
Purpose: This study was conducted to evaluate the changes in neuropsychological functioning in patients with temporal lobe epilepsy (TLE) after temporal lobe resection. Methods: Fifty-four TLE patients were evaluated before and after surgery using comprehensive neuropsychological tests to assess general intelligence, executive functioning, language, verbal and visual memory, working memory, visuo-spatial ability, attention and motor function. Results: The patients with left TLE showed no impairment of neuropsychological functioning after surgery, with the exception of auditory immediate memory. Furthermore, they showed significant improvement in performance IQ, executive function, working memory, visual memory, attention and psychomotor speed. The patients with right TLE did not show any significant impairment in post-operative neuropsychological functioning. They showed improvements in intellectual and executive functions, language, visual memory, visuo-spatial ability, attention and motor function post-operatively. The patients with hippocampal sclerosis showed greater post-operative improvements than the patients without hippocampal sclerosis regardless of the side. Patients with better pre-operative neuropsychological function had a higher chance of successfully discontinuing all seizure medications after surgery. Discussion: The results of this study suggest that temporal lobectomy does not harm the neuropsychological functioning of patients with intractable TLE and that it improves cognitive functions of the contralateral hemisphere. © 2009 W. S. Maney & Son Ltd
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