Self-assembled quantum dots: A study of strain energy and intersubband transitions

In this article we examine the strain energy and intersubband optical transitions in self-assembled dots on GaAs and InP substrates. On the GaAs substrate, in addition to the InAs/GaAs dots we examine strain compensated InAs/GaAsP dots on GaAs substrates. We find that the strain energy configuration profile shows that there is preference for certain dot sizes and shapes. Our calculated dot sizes agree well with experimental observations. We find that the addition of phosphorus in the covering matrix reduces the total strain energy of the system with little effects on the intersubband transition strength for the vertical incident light. The reduced strain energy should allow one to incorporate a large number of dot array stacks for devices such as lasers and detectors and thus increases the optical responses. Our studies for the InAs/InP system show that due to the lower strain mismatch there is no particular preference for dot sizes. The optical response for intersubband transitions is weaker and occurs at longer wavelengths in comparison to the InAs/GaAs dots. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71038/2/JAPIAU-92-10-6205-1.pd

Theory of polarization dependent intersubband transitions in p-type SiGe/Si self-assembled quantum dots

Electronic and optoelectronic properties of SiGe/Si self-assembled quantum dots are calculated by the eight-band k⋅p method with a revised set of parameters. The model confirms that the Si1−xGexSi1−xGex transforms to a type-II structure when x is greater than 0.25 and given accurate effective masses for Si and Ge. The polarization dependent absorption spectra show a behavior quite different from what is seen in conduction band intersubband transitions in self-assembled InGaAs/GaAs dots. In-plane or x-polarized absorption increases as germanium content is increased but z-polarized absorption is highest for low germanium content. It is also shown that the z-polarized absorption can be of the same magnitude as in the x-direction by adjusting the dot composition. We also clarify how the envelope functions and the Block parts of the electronic states contribute to the absorption spectra. © 2004 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69715/2/JAPIAU-96-2-1059-1.pd

Prediction Model of End Mill Cutting Edge Based on Material Properties and Cutting Conditions

In machining, the cutting performance of the tool depends on the tool material, tool structure, tool geometry, properties of workpiece materials, and cutting conditions. If the user chooses an inappropriate cutting tool for the machining of the workpiece material, this will cause energy loss and severe tool wear. This study aims to investigate the influence of mechanical properties of workpiece material and cutting conditions on the tool geometry and to establish a polynomial network for the prediction of a reasonable normal relief angle and a normal wedge angle based on experimental data. Experimental results indicate that the cutting of high hardness and high strength workpiece materials requires a larger normal wedge angle to increase the cutting edge strength. In addition, the design of the normal relief angle is related to Young\u27s modulus and the toughness of the workpiece material, mainly to avoid material elastic recovery during the cutting process. In terms of cutting parameters, as the radial depth of cut increases, the contact area between the tool and the chip increases, which causes the heat to concentrate at the tip of the tool; hence, it is necessary to increase the normal wedge angle. In addition, the feed per tooth had a negligible effect on the normal wedge angle. Finally, the prediction model was verified by five untested workpiece materials. The results of the cutting tests showed that the flatness of the cutting edge was less than 15 μm, which indicates that a normal cutting phenomenon occurred on the flank

Study of charge control and gate tunneling in a ferroelectric-oxide-silicon field effect transistor: Comparison with a conventional metal-oxide-silicon structure

It is known that conventional metal-oxide-silicon (MOS) devices will have gate tunneling related problems at very thin oxide thicknesses. Various high-dielectric-constant materials are being examined to suppress the gate currents. In this article we present theoretical results of a charge control and gate tunneling model for a ferroelectric-oxide-silicon field effect transistor and compare them to results for a conventional MOS device. The potential of high polarization charge to induce inversion without doping and high dielectric constant to suppress tunneling current is explored. The model is based on a self-consistent solution of the quantum problem and includes the ferroelectric hysteresis response self-consistently. We show that the polarization charge associated with ferroelectrics can allow greater controllability of the inversion layer charge density. Also the high dielectric constant of ferroelectrics results in greatly suppressed gate current. © 2001 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71117/2/JAPIAU-89-3-1856-1.pd

Effects of Yoga on Psychological Health, Quality of Life, and Physical Health of Patients with Cancer: A Meta-Analysis

Yoga is one of the most widely used complementary and alternative medicine therapies to manage illness. This meta-analysis aimed to determine the effects of yoga on psychological health, quality of life, and physical health of patients with cancer. Studies were identified through a systematic search of seven electronic databases and were selected if they used a randomized controlled trial design to examine the effects of yoga in patients with cancer. The quality of each article was rated by two of the authors using the PEDro Scale. Ten articles were selected; their PEDro scores ranged from 4 to 7. The yoga groups compared to waitlist control groups or supportive therapy groups showed significantly greater improvements in psychological health: anxiety (P = .009), depression (P = .002), distress (P = .003), and stress (P = .006). However, due to the mixed and low to fair quality and small number of studies conducted, the findings are preliminary and limited and should be confirmed through higher-quality, randomized controlled trials

Development of inspection system for tool presetter

In order to conform to the concept of smart factory for industry 4.0, this paper developed a low-cost tool measuring machine included the structure design, hardware planning of the server, electromechanical control, drive system, human machine interface, communication between hardware and software, software development, and so on. The proposed measuring system provided more flexibility and integration with peripheral equipment for the requirements of industry 4.0. Compared with a Germanic measuring machine, experimental results showed that the percentage of errors of the designed inspection instrument were 0.004 ％ and 0.003 ％ for the tool length and diameter measurements of a square end mill, respectively

Hepcidin Regulation by BMP Signaling in Macrophages Is Lipopolysaccharide Dependent

Hepcidin is an antimicrobial peptide, which also negatively regulates iron in circulation by controlling iron absorption from dietary sources and iron release from macrophages. Hepcidin is synthesized mainly in the liver, where hepcidin is regulated by iron loading, inflammation and hypoxia. Recently, we have demonstrated that bone morphogenetic protein (BMP)-hemojuvelin (HJV)-SMAD signaling is central for hepcidin regulation in hepatocytes. Hepcidin is also expressed by macrophages. Studies have shown that hepcidin expression by macrophages increases following bacterial infection, and that hepcidin decreases iron release from macrophages in an autocrine and/or paracrine manner. Although previous studies have shown that lipopolysaccharide (LPS) can induce hepcidin expression in macrophages, whether hepcidin is also regulated by BMPs in macrophages is still unknown. Therefore, we examined the effects of BMP signaling on hepcidin expression in RAW 264.7 and J774 macrophage cell lines, and in primary peritoneal macrophages. We found that BMP4 or BMP6 alone did not have any effect on hepcidin expression in macrophages although they stimulated Smad1/5/8 phosphorylation and Id1 expression. In the presence of LPS, however, BMP4 and BMP6 were able to stimulate hepcidin expression in macrophages, and this stimulation was abolished by the NF-κB inhibitor Ro1069920. These results suggest that hepcidin expression is regulated differently in macrophages than in hepatocytes, and that BMPs regulate hepcidin expression in macrophages in a LPS-NF-κB dependent manner

The 2005 Ilan earthquake doublet and seismic crisis in northeastern Taiwan: evidence for dyke intrusion associated with on-land propagation of the Okinawa Trough

Northern Taiwan underwent mountain building in the early stage of the Taiwan orogeny but is currently subjected to post-collisional crustal extension. It may be related to gravitational collapse or to the rifting of the Okinawa Trough, which lies offshore northeastern Taiwan. The Ilan Plain, northeastern Taiwan, which is bounded by the normal fault systems and filled up with thick Pliocene–Pleistocene sedimentary sequences, formed under such an extension environment. Over there on 2005 March 5 two earthquakes with about the same magnitude (M_L = 5.9) occurred within 68 s and produced intense aftershocks activity according to the records of Central Weather Bureau Seismic Network of Taiwan. We relocated the earthquake sequence by the three-dimension earthquake location algorithm with the newly published 3-D Vp and Vp/Vs velocity model, and determined the first-polarity focal mechanisms of the earthquake doublet. One major cluster of aftershocks which trends E–W and dips steeply to the south can be identified and picked up as a potential fault plane. The focal mechanisms of the two main shocks are both classified as normal type by first-polarity but strike-slip by centroid moment tensor inversion; however two methods both yield consistent E–W strike. Static coseismic deformation was additionally determined from Global Positioning System (GPS) daily solutions at a set of continuous GPS stations and from strong-motion seismographs. These data show NW–SE extension at high angle to the fault plane, which cannot be explained from a simple strike-slip double-couple mechanism. On the other hand, the small vertical displacements and steep fault plane cannot be explained from a simple normal event as well. We present from elastic dislocation modelling that the geodetic data are best explained by significant component of tensile source with centimetre-scale of opening on a 15-km-long fault extending from 1 to 13 km depth. We therefore interpret the crisis as the result of dyke intrusion at the very tip of the Okinawa Trough, which is reasonably driven by backarc spreading

Effect of patient decision aids on choice between sugammadex and neostigmine in surgeries under general anesthesia: a multicenter randomized controlled trial

Background Shared decision making using patient decision aids (PtDAs) was established over a decade ago, but few studies have evaluated its efficacy in Asian countries. We therefore evaluated the application of PtDAs in a decision conflict between two muscle relaxant reversal agents, neostigmine and sugammadex, and sequentially analyzed the regional differences and operating room turnover rates. Methods This multicenter, outcome-assessor-blind, randomized controlled trial included 3,132 surgical patients from two medical centers admitted between March 2020 and August 2020. The patients were randomly divided into the classical and PtDA groups for pre-anesthesia consultations. Their clinicodemographic characteristics were analyzed to identify variables influencing the choice of reversal agent. On the day of the pre-anesthesia consultation, the patients completed the four SURE scale (sure of myself, understand information, risk-benefit ratio, encouragement) screening items. The operating turnover rates were also evaluated using anesthesia records. Results Compared with the classical group, the PtDA group felt more confident about receiving sufficient medical information (P < 0.001), felt better informed about the advantages and disadvantages of the medications (P < 0.001), exhibited a superior understanding of the benefits and risks of their options (P < 0.001), and felt surer about their choice (P < 0.001). Moreover, the PtDA group had a significantly greater tendency to choose sugammadex over neostigmine (P < 0.001). Conclusions PtDA interventions in pre-anesthesia consultations provided surgical patients with clear knowledge and better support. PtDAs should be made available in other medical fields to enhance shared clinical decision-making