Stress and its effect on optical properties of AlN nanorods

2009-2010 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

π Junction to probe antiphase s-Wave pairing in iron pnictide superconductors

Josephson junctions between a FeAs-based superconductor with antiphase s-wave pairing and a conventional s-wave superconductor are studied. The translational invariance in a planar junction between a single crystal pnictide and an aluminum metal greatly enhances the relative weight of electron pockets in the pnictide to the critical current. In a wide doping region of the pnictide, a planar and a point contact junction have opposite phases, which can be used to design a trijunction ring with π phase to probe the antiphase pairing. © 2009 The American Physical Society.published_or_final_versio

A Novel Biphasic-Current-Pulse Calibration Technique for Electrical Neural Stimulation

One of the major challenge in neural prosthetic device design is to ensure charge-balanced stimulation. This paper presents a new calibration technique to minimize the mismatch between anodic and cathodic current amplitudes. The proposed circuit mainly consists of a digital and an analog calibration, where a successive approximation register (SAR) logic and a comparator are used in digital calibration while a source follower is adopted in analog calibration. With a 0. 18 μm high voltage CMOS process, the simulation shows that the maximum current mismatch is 45 nA (<0.05%).published_or_final_versio

A movable image-based rendering system and its application to multiview audio-visual conferencing

Image-based rendering (IBR) is an emerging technology for rendering photo-realistic views of scenes from a collection of densely sampled images or videos. It provides a framework for developing revolutionary virtual reality and immersive viewing systems. This paper studies the design of a movable image-based rendering system based on a class of dynamic representations called plenoptic videos. It is constructed by mounting a linear array of 8 video cameras on an electrically controllable wheel chair with its motion being controllable manually or remotely through wireless LAN by means of additional hardware circuitry. We also developed a real-time object tracking algorithm and utilize the motion information computed to adjust continuously the azimuth or rotation angle of the movable IBR system in order to cope with a given moving object. Due to the motion of the wheel chair, videos may appear shaky and video stabilization technique is proposed to overcome this problem. The system can be used in a multiview audio-visual conferencing via a multiview TV display. Through this pilot study, we hope to develop a framework for designing movable IBR systems with improved viewing freedom and ability to cope with moving object in large environment. ©2010 IEEE.published_or_final_versionThe 10th International Symposium on Communications and Information Technologies (ISCIT 2010), Tokyo, Japan, 26-29 October 2010. In Proceedings of 10th ISCIT, 2010, p. 1142-114

Knowledge discovery for friction stir welding via data driven approaches: Part 2 – multiobjective modelling using fuzzy rule based systems

In this final part of this extensive study, a new systematic data-driven fuzzy modelling approach has been developed, taking into account both the modelling accuracy and its interpretability (transparency) as attributes. For the first time, a data-driven modelling framework has been proposed designed and implemented in order to model the intricate FSW behaviours relating to AA5083 aluminium alloy, consisting of the grain size, mechanical properties, as well as internal process properties. As a result, ‘Pareto-optimal’ predictive models have been successfully elicited which, through validations on real data for the aluminium alloy AA5083, have been shown to be accurate, transparent and generic despite the conservative number of data points used for model training and testing. Compared with analytically based methods, the proposed data-driven modelling approach provides a more effective way to construct prediction models for FSW when there is an apparent lack of fundamental process knowledge

Current concepts in odontohypophosphatasia form of hypophosphatasia and report of two cases

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Patient-derived iPSCs show premature neural differentiation and neuron type-specific phenotypes relevant to neurodevelopment.

Ras/MAPK pathway signaling is a major participant in neurodevelopment, and evidence suggests that BRAF, a key Ras signal mediator, influences human behavior. We studied the role of the mutation BRAFQ257R, the most common cause of cardiofaciocutaneous syndrome (CFC), in an induced pluripotent stem cell (iPSC)-derived model of human neurodevelopment. In iPSC-derived neuronal cultures from CFC subjects, we observed decreased p-AKT and p-ERK1/2 compared to controls, as well as a depleted neural progenitor pool and rapid neuronal maturation. Pharmacological PI3K/AKT pathway manipulation recapitulated cellular phenotypes in control cells and attenuated them in CFC cells. CFC cultures displayed altered cellular subtype ratios and increased intrinsic excitability. Moreover, in CFC cells, Ras/MAPK pathway activation and morphological abnormalities exhibited cell subtype-specific differences. Our results highlight the importance of exploring specific cellular subtypes and of using iPSC models to reveal relevant human-specific neurodevelopmental events

Thermal field over Tibetan Plateau and Indian summer monsson rainfall

The interannual variability of the temperature anomalies over the Tibetan Plateau (25-45 °N, 75-105 °E) is examined in relation to the Indian summer monsoon rainfall (ISMR: June to September total rainfall). For this purpose, the temperature anomaly data of the central-eastern Tibetan Plateau is divided into three regions using principal component analysis and the ISMR data for the period 1957-89 have been used. It is found that the January temperature anomaly of Region 2 has a significant negative relationship (r = -0.67) with the ISMR of the subsequent season. This region is located over the northeastern part of the Tibetan Plateau, mostly in Qinghai province, including the Bayan Harr Mountain range and the Qaidam Basin. This relationship is consistent and robust during the period of analysis and can be used to predict the strength of the Indian summer monsoon in the subsequent season. It was found that the January temperature anomaly in this region was associated with a persistent winter circulation pattern over the Eurasian continent during January through to March. Finally, the variation patterns of the temperature anomalies in all three regions over the central-eastern Tibetan Plateau during extreme years of the ISMR are examined. It is concluded that the January temperature anomaly over the northeastern Tibetan Plateau can be useful in forecasting the drought and flood conditions over India, especially in predicting the monsoon rainfall over the areas lying along the monsoon trough

A predictive continuum dynamic user-optimal model for a polycentric urban city

A predictive continuum dynamic user-optimal model is extended to investigate the traffic equilibrium problem for a polycentric urban city with multiple central business districts (CBDs). The road network within the city is assumed to be dense and can be viewed as a continuum in which travellers can choose their routes in a two-dimensional space. Travellers are assumed to choose their route to minimise the actual total cost to the destination (i.e. the CBD). The model consists of two parts: the conservation law part and the Hamilton–Jacobi part. The finite volume method is used to solve each part on unstructured meshes. Because the two parts are closely interconnected and have different initial times, solving the model can be treated as a fixed-point problem, which is solved using a self-adaptive method of successive averages. Numerical experiments for an urban city with two CBDs are presented to demonstrate the effectiveness of the model and the numerical algorithm.postprin

Macroscopic Klein tunneling in spin-orbit-coupled Bose-Einstein condensates

We propose an experimental scheme to detect macroscopic Klein tunneling with spin-orbit-coupled Bose-Einstein condensates (BECs). We show that a nonlinear Dirac equation with tunable parameters can be realized with such BECs. Through numerical calculations, we demonstrate that macroscopic Klein tunneling can be clearly detected under realistic conditions. Macroscopic quantum coherence in such relativistic tunneling is clarified and a BEC with a negative energy is shown to be able to transmit transparently through a wide Gaussian potential barrier. © 2012 American Physical Society.published_or_final_versio