Discriminative Stimulus, Reinforcing, Physical Dependence, and Antinociceptive Effects of Oxycodone in Mice, Rats, and Rhesus Monkeys.

Despite oxycodone's (4,5-epoxy-14-hydroxy-3-methoxy-17-methylmorphinan-6-one) history of clinical use and the attention it has received as a drug of abuse, few reports have documented its pharmacology's relevance to its abuse or its mechanism of action. The purposes of the present study were to further characterize the analgesic effects of oxycodone, its mechanism of action, and its effects in terms of its relevance to its abuse liability. The results indicate that oxycodone had potent antinociceptive effects in the mouse paraphenylquinone writhing, hot-plate, and tail-flick assays, in which it appeared to be acting as a μ-opioid receptor agonist. It generalized to the heroin discriminative stimulus and served as a positive reinforcer in rats and completely suppressed withdrawal signs in morphinedependent rhesus monkeys. These results suggest that the analgesic and abuse liability effects of oxycodone are likely mediated through μ-opioid receptors and provide the first laboratory report of its discriminative stimulus, reinforcing, and morphine cross-dependency effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

开关电容ADC及其驱动放大器之间的阻抗谐振匹配方法

高采样速率模数转换器（ADC）通常用在现代无线接收器设计中,以中频（IF）采样速率采集复数调制的信号.这类设计通常都选用基于CMOS开关电容的ADC,因为它们的低成本和低功耗特点很吸引人。但这类ADC采用一种直接连接到采样网络的无缓冲器的前端,这样就会出现驱动ADC的放大器的输入跟踪和保持阻抗随时间变化的问题.为了有效地驱动ADC,使噪声最低和有用信号失真最小,必须设计一种无源网络接口帮助抑制宽带噪声,并对跟踪阻抗和保持阻抗进行变换以便为驱动放大器提供更好的负载阻抗。针对几种常见的IF频率,本文中提出了一种谐振匹配方法,用于将跟踪和保持阻抗转换为比较容易计算的负载,从而实现抗锯齿滤波器的精密设计。     

Analysis of ferrite circulators by 2-D finite-element and recursiveGreen's function techniques

Ferrite circulator operation is analyzed here by two techniques. The first employs a two-dimensional (2-D) finite-element (FE) technique, using a publicly available FE package. We show how to adapt this code to the solution of the magnetostatic equations and solve for the distribution of internal magnetic field inside a round ferrite puck of finite thickness, and use it to verify existing approximations for the demagnetizing fields. Additionally, the 2-D FE method has also been used to calculate the RF fields and scattering parameters in circulators having noncircular shapes, as well as nonuniform material properties and bias conditions. We have also investigated the field solutions for round circulators, calculated using a recursive Green's function (RGF) technique. This technique allows for radially varying properties in the material or bias fields, and thus accommodates the nonuniform demagnetizing field distribution in finite pucks. A comparison of the results of this technique with experiment is made. We show how the impedance-matching structures attached to the circulator affect the field distributions inside, and present plots of the field distributions as a function of frequency, which provide insight into circulator operation     

Signal cancellation phenomena in adaptive antennas: Causes and cures

Conventional adaptive beamformers utilizing some form of automatic minimization of mean square error exhibit signal cancellation phenomena when adapting rapidly. These effects result from adaptive interaction between signal and interference, when signal and interference are received simultaneously. Similar phenomena have been observed and analyzed in relatively simple adaptive noise cancelling systems. A study of these phenomena in the simpler systems is used to provide insight into similar behavior in adaptive antennas. A method for alleviating signal cancellation has been devised by Duvall, whereby the signal components are removed from the adaptive process, then reinserted to form the final system output. Widrow has devised a different solution to the problem: to move the receiving array spatially (or electronically) to modulate emanations received off the look direction, without distorting useful signals incident from the look direction. This approach is called "spatial dither" and introduces the additional possibility of modulating "smart" jammer signals, thereby limiting their effectiveness.