Limiting efficiencies of solar energy conversion and photo-detection via internal emission of hot electrons and hot holes in gold

We evaluate the limiting efficiency of full and partial solar spectrum harvesting via the process of internal photoemission in Au-semiconductor Schottky junctions. Our results based on the ab initio calculations of the electron density of states (e-DOS) reveal that the limiting efficiency of the full-spectrum Au converter based on hot electron injection is below 4%. This value is even lower than previously established limit based on the parabolic approximation of the Au electron energy bands. However, we predict limiting efficiency exceeding 10% for the hot holes collection through the Schottky junction between Au and p-type semiconductor. Furthermore, we demonstrate that such converters have more potential if used as a part of the hybrid system for harvesting high- and low-energy photons of the solar spectrum.Comment: Proc. SPIE 9608, Infrared Remote Sensing and Instrumentation XXIII, 960816 (September 1, 2015) 7 pages, 4 figure

A Behavioural and Cognitive Neuroscience Investigation of Deceptive Communication

There is a rich literature on how people tell lies and detect them in others, but the underlying mechanisms are still poorly understood. The first aim of this thesis was to elucidate key cognitive and neural processes underlying cued (i.e., instructed) and uncued lies. The second aim, based on recent research suggesting a link between dishonesty and creativity, was to determine whether creative cognition contributes to deceptive communication. In a first behavioural study, performance on generating and detecting lies was measured in a socially interactive setting involving cued and uncued lies. Results of a multiple regression analysis showed that creativity predicted lying generation ability: more creative individuals were better liars than less creative people. In contrast, the ability to detect lies showed no association with creativity measures, suggesting that generating and detecting lies are distinct abilities. A second event-related potential (ERP) study investigated the neural mechanisms underlying the generation of uncued lies using a novel bluffing paradigm where participants lied at will. Results showed no stimulus-locked differences between uncued lies and truths, suggesting that decision processes leading to both required comparable cognitive resources. Once the uncued decision has been made, it requires strategic monitoring to keep track of the responses in order to maximize the gains regardless of whether the outcome is a lie or the truth as indexed by no response-locked differences between uncued lies and truths. Finally, parallel functional magnetic resonance imaging (fMRI) and ERP studies were conducted to determine the role of creativity in countermeasure use in a concealed information paradigm requiring cued lying. Results showed that countermeasures degraded the neural signatures of deception and more so for more creative individuals. This work advances understanding of the cognitive and neural mechanisms underlying deception as well as their dependence on individual differences in creative cognition

Challenges and Solutions for High Performance Analog Circuits with Robust Operation in Low Power Digital CMOS

In modern System-on-Chip products, analog circuits need to co-exist with digital circuits integrated on the same chip. This brings on a lot of challenges since analog circuits need to maintain their performance while being subjected to disturbances from the digital circuits. Device size scaling is driven by digital applications to reduce size and improve performance but also results in the need to reduce the supply voltage. Moreover, in some applications, digital circuits require a changing supply voltage to adapt performance to workloads. So it is further desirable to develop design solutions for analog circuits that can operate with a flexible supply voltage, which can be reduced well below 1V. In this thesis challenges and solutions for key high performance analog circuit functions are explored and demonstrated that operate robustly in a digital environment, function with flexible supply voltages or have a digital-like operation. A combined phase detector consisting of a phase-frequency detector and sub-sampling phase detector is proposed for phase-locked loops (PLLs). The phase-frequency function offers robust operation and the sub-sampling detector leads to low in-band phase noise. A 2.2GHz PLL with a combined phase detector was prototyped in a 65nm CMOS process, with an on-chip loop filter area of only 0.04mm². The experimental results show that the PLL with the combined phase detector is more robust to disturbances than a sub-sampling PLL, while still achieving a measured in-band phase noise of -122dBc/Hz which is comparable to the excellent noise performance of a sub-sampling PLL. A pulse-controlled common-mode feedback (CMFB) circuit is proposed for a 0.6V-1.2V supply-scalable fully-differential amplifier that was implemented in a low power/leakage 65nm CMOS technology. An integrator built with the amplifier occupies an active area of 0.01mm². When the supply is changed from 0.6V to 1.2V, the measured frequency response changes are small, demonstrating the flexible supply operation of the differential amplifier with the pulse-controlled CMFB. Next, models are developed to study the performance scaling of a continuous-time sigma-delta modulator (SDM) with a varying supply voltage. It is demonstrated that the loop filter and the quantizer exhibit different supply dependence. The loop noise performance becomes better at a higher supply thanks to larger signal swings and better signal-to-noise ratio, while the figure of merit determined by the quantization noise gets better at a lower supply voltage, thanks to the quantizer power dissipation reduction. The theoretical models were verified with simulations of a 0.6V-1.2V 2MHz continuous-time SDM design in a 65nm CMOS low power/leakage process. Finally, two design techniques are introduced that leverage the continued improvement of digital circuit blocks for the realization of analog functions. A voltage-controlled-ring-oscillator-based amplifier with zero compensation is proposed that internally uses a phase-domain representation of the analog signal. This provides a huge DC gain without significant penalties on the unity-gain bandwidth or area. With this amplifier a 4th-order 40-MHz active-UGB-RC filter was implemented that offers a wide bandwidth, superior linearity and small area. The filter prototype in a 55nm CMOS process has an active area of 0.07mm² and a power consumption of 7.8mW at 1.2V. The in-band IIP3 and out-of-band IIP3 are measured as 27.3dBm and 22.5dBm, respectively. A digital in-situ biasing technique is proposed to overcome the design challenges of conventional analog biasing circuits in an advanced CMOS process. A digital CMFB was simulated in a 65nm CMOS technology to demonstrate the advantages of this digital biasing scheme. Using time-based successive approximation conversion, the digital CMFB provides the desired analog output with a more robust operation and a smaller area, but without needing any stability compensation schemes like in conventional analog CMFBs. In summary, analog design techniques are continuously evolving to adapt to the integration with digital circuits on the same chip and are increasingly using digital-like blocks to realize analog functions in highly-integrated SOC chips. The signal representation in analog circuits is moving from traditional electrical signals such as voltage or current, to time and phase-domain representations. These changes make analog circuits more robust to voltage disturbances and supply variations. In addition to improved robustness, analog circuits based on timing signals benefit from the faster and smaller transistors offered by the continued feature scaling in CMOS technologies

Intelligent Second-Order Sliding-Mode Control for Chaotic Tracking Problem

[[conferencetype]]國際[[conferencedate]]20140909~20140912[[booktype]]紙本[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]Sapporo, Japa

Adhesive L1CAM-Robo Signaling Aligns Growth Cone F-Actin Dynamics to Promote Axon-Dendrite Fasciculation in C. elegans

Neurite fasciculation through contact-dependent signaling is important for the wiring and function of the neuronal circuits. Here, we describe a type of axon-dendrite fasciculation in C. elegans, where proximal dendrites of the nociceptor PVD adhere to the axon of the ALA interneuron. This axon-dendrite fasciculation is mediated by a previously uncharacterized adhesive signaling by the ALA membrane signal SAX-7/L1CAM and the PVD receptor SAX-3/Robo but independent of Slit. L1CAM physically interacts with Robo and instructs dendrite adhesion in a Robo-dependent manner. Fasciculation mediated by L1CAM-Robo signaling aligns F-actin dynamics in the dendrite growth cone and facilitates dynamic growth cone behaviors for efficient dendrite guidance. Disruption of PVD dendrite fasciculation impairs nociceptive mechanosensation and rhythmicity in body curvature, suggesting that dendrite fasciculation governs the functions of mechanosensory circuits. Our work elucidates the molecular mechanisms by which adhesive axon-dendrite signaling shapes the construction and function of sensory neuronal circuits

Finding Related Publications: Extending the Set of Terms Used to Assess Article Similarity.

Recommendation of related articles is an important feature of the PubMed. The PubMed Related Citations (PRC) algorithm is the engine that enables this feature, and it leverages information on 22 million citations. We analyzed the performance of the PRC algorithm on 4584 annotated articles from the 2005 Text REtrieval Conference (TREC) Genomics Track data. Our analysis indicated that the PRC highest weighted term was not always consistent with the critical term that was most directly related to the topic of the article. We implemented term expansion and found that it was a promising and easy-to-implement approach to improve the performance of the PRC algorithm for the TREC 2005 Genomics data and for the TREC 2014 Clinical Decision Support Track data. For term expansion, we trained a Skip-gram model using the Word2Vec package. This extended PRC algorithm resulted in higher average precision for a large subset of articles. A combination of both algorithms may lead to improved performance in related article recommendations

Reducing Side Effects of Hiding Sensitive Itemsets in Privacy Preserving Data Mining

Data mining is traditionally adopted to retrieve and analyze knowledge from large amounts of data. Private or confidential data may be sanitized or suppressed before it is shared or published in public. Privacy preserving data mining (PPDM) has thus become an important issue in recent years. The most general way of PPDM is to sanitize the database to hide the sensitive information. In this paper, a novel hiding-missing-artificial utility (HMAU) algorithm is proposed to hide sensitive itemsets through transaction deletion. The transaction with the maximal ratio of sensitive to nonsensitive one is thus selected to be entirely deleted. Three side effects of hiding failures, missing itemsets, and artificial itemsets are considered to evaluate whether the transactions are required to be deleted for hiding sensitive itemsets. Three weights are also assigned as the importance to three factors, which can be set according to the requirement of users. Experiments are then conducted to show the performance of the proposed algorithm in execution time, number of deleted transactions, and number of side effects