Successful Aging

This issue's Works in Progress department presents six abstracts for projects that are developing interesting solutions to the elderly's quality of life challenges. The first two abstracts discuss projects that will help provide the elderly with freedom and independence by instrumenting their environments with supportive technology. The next two abstracts discuss projects building specialized user interfaces for addressing some of the challenges associated with aging, such as vision impairment. The final two abstracts present projects that will aid independence for the elderly by providing remote monitoring and assistance.     

立方相GaN的持续光电导

研究了金属有机物化学气相外延 (MOVPE)方法生长的非故意掺杂的立方相 Ga N的持续光电导效应 .在六方相 Ga N中普遍认为持续光电导效应与黄光发射有关 ,而实验则显示在立方 Ga N中 ,持续光电导效应与其中的六方相 Ga N夹杂有关系 ,而与黄光发射没有关系 .文中提出 ,立方相 Ga N与其中的六方相 Ga N夹杂之间的势垒引起的空间载流子分离是导致持续光电导现象的物理原因 .通过建立势垒限制复合模型 ,解释了立方相 Ga N的持续光电导现象的物理过程 ,并对光电导衰减过程的动力学作了分析 .对实验数据拟合的结果证明以上的模型和推导是与实验相符的 .     

Realization of modular multidimensional complex digital filters using GIC concept

It is known that complex digital filters possess certain advantages over real digital filters in processing complex signals such as increased computational speed and efficiency. In this paper, a simple and systematic procedure which can be implemented through a computer program is presented for realizing a specific class of multidimensional (M-D) complex digital filters. The proposed filter structures are derived from analog reference configurations comprising generalized immittance converters and resistors by making use of wave concept. These filters possess many salient properties such as low noise, low sensitivity and capability of realizing multiple transfer functions simultaneously which are inherited from the reference analog filters they are derived from. These features make them attractive for very large-scale integrated (VLSI) implementation. It is shown that the proposed filter structures can be obtained directly from the specified M-D discrete transfer function without the need for realizing any analog reference configuration.     

The Amygdala Modulates Hippocampus-Dependent Context Memory Formation and Stores Cue-Shock Associations.

Preexposing rats to the context facilitates subsequent contextual fear conditioning. This effect depends on the hippocampus (J. W. Rudy, R. M. Barrientos, & R. C. O'Reilly, 2002). The authors report that inactivating the basolateral region of the amygdala (BLA) by injecting muscimol, a GABAA agonist, before or after preexposure reduced this effect. In contrast, bilateral injections of anisomycin, a protein synthesis inhibitor, into BLA did not impair the consolidation of the context memory. However, when injected after fear conditioning, anisomycin impaired consolidation of both contextual and auditory-cue fear conditioning. Results are consistent with 2 ideas about the amygdala's contribution to memory: (a) It modulates memory formation in other regions of the brain, and (b) it is a storage site for cue-shock associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term frequency stability of clock generators for multigigahertz rapid-single-flux quantum digital circuits

Superconducting digital systems based on Josephson junctions have generally used a synchronous timing strategy. A master clock signal is used to delimit a data window during which the system changes state and data is transferred from one block to the next. The temporal stability of the clock signal has a profound effect on the performance of rapid single flux quantum (RSFQ) digital systems. In particular, short-term clock fluctuations, or clock jitter, can degrade system performance due to the hazard of timing constraint violations. The successful development of large-scale RSFQ digital systems will require highly stable multigigahertz on-chip clock sources. To meet this need, methods for characterizing and measuring the short-term stability of such sources are required. We identify the relevant figure of merit to characterize and compare various clocks: the cycle-to-cycle standard deviation of the clock periods. We present experimental techniques for the measurement of this figure of merit and apply them to the measurement of jitter in a clock generator used often in RSFQ systems, the ring oscillator. High-frequency phase noise measurements found the jitter of a 9.6-GHz clock to be in the range from 0.6% to 0.36% of the clock period. The measured values of clock jitter fell within the 95% confidence interval of our stochastic circuit simulations. This was sufficient evidence to conclude that thermal noise from the resistors in the circuit may be the dominant source of jitter in the ring oscillator.     

FDTD simulation of 30 /spl mu/m diameter polymer micro-ring

Numerical results on polymer surrounded by an air micro-ring coupled to waveguides are presented. The FDTD method predicts a filter width of 1.4 nm and an extraction efficiency of almost 80% for a gap of 0.15 /spl mu/m.     

Examining pre-adoption interest in online innovations: an exploratory study of e-service personalization in the public sector

In order to better understand why public organizations develop interest in online innovations, this paper develops a revised model of technological innovation with an emphasis on socio-technical factors associated with electronic service delivery. This model focuses on three primary dimensions of online innovation: perceived need, technical capacity, and risk mitigation. It is hypothesized that these three dimensions will have the greatest influence on the development of pre-adoption interest in a new online innovation. This model is then used to examine a single online innovation, personalization of online government information and services. Data from a survey of local governments is used to test the theory. A regression model was estimated from the survey data. Results suggest that perceived need, financial costs, and the ability to mitigate the risks associated with privacy issues each influence the level of interest in personalized online services. The results suggest that public organizations must find reliable means of determining external demand for online innovations, as well as reducing the risks associated with each specific type of online innovation prior to adoption.     

A push mechanism for GPRS supporting private IP addresses

The General Packet Radio Service (GPRS) provides a packet switched data service for mobile users. However, the existing GPRS specification does not provide the push mechanism and it is difficult to support GPRS services such as call termination (incoming call) for wireless voice over IP (VoIP). Based on the short message service, this paper proposes a push mechanism for GPRS supporting private IP addresses. Our approach does not need to modify the existing GPRS structure.