Lightning protection for microprocessor-based electronic systems

The issues of lightning threats, suppressor components, and guidelines for selection and placement of protectors are addressed. Case histories are also reviewed. It is noted that current complex, multifunctional electronic systems are composed mainly of sophisticated microcircuits that are extremely vulnerable to lightning-caused transient voltage spikes. Properly selected and installed surge protection devices have a long history of proven capability in virtually eliminating costly downtime and repairs. Telecommunication station protectors usually allow voltage spikes of 500 V or more to pass on through to downstream equipment. They are designed for protection of personnel and also equipment that the telephone company connects to the system. Modems and other interfaces may not have built-in hardness to sustain 500 V spikes or adequately protect against temporary malfunctions. Supplemental protective devices for modems and other signal lines can boost transient immunity by orders of magnitude with a relatively low investment     

Digital mammography: M-channel quadrature mirror filters (QMFs) for microcalcification extraction

Multiresolution methods are reported for feature extraction in breast cancer screening using digital mammography. The initial application is directed at the detection of microcalcification clusters (MCCs). Quadrature mirror filter (QMF) banks, using both two and three channel are proposed for the first time for both multiresolution decomposition and reconstruction. These filters are specifically tailored for automatic extraction of MCCs. The QMF multiresolution methods are compared to two channel tree structured wavelet transforms (TSWTs) methods previously reported. The QMF filters are preceded by an advanced tree structured nonlinear filter for noise suppression, prior to feature extraction, in order to minimize the false positive (FP) detection rate in digital mammography. The relative performance of these methods were evaluated using both simulated images and fifteen representative digitized mammograms containing biopsy proven microcalcification clusters. Similar high sensitivity (true positive (TP) detection rate (100%) and high specificity (0.6 average false positive (FP) MCC's/image) were observed, substantially better than more traditional approaches using single scale filters. The three channel QMF method, however, demonstrated better detail preservation of MCC's extracted compared to the two channel method. Detail preservation is important for the characterization of MCC's or individual microcalcifications in cancer screening.     

Effects of spatial cuing on luminance detectability: Psychophysical and electrophysiological evidence for early selection.

Three experiments were conducted to determine whether attention-related changes in luminance detectability reflect a modulation of early sensory processing. Exps 1 and 2 used peripheral cues to direct attention and found substantial effects of cue validity on target detectability; these effects were consistent with a sensory-level locus of selection but not with certain memory- or decision-level mechanisms. In Exp 3, event-related brain potentials were recorded in a similar paradigm using central cues, and attention was found to produce changes in sensory-evoked brain activity beginning within the 1st 1 msec of stimulus processing. These changes included both an enhancement of sensory responses to attended stimuli and a suppression of sensory responses to unattended stimuli; the enhancement and suppression effects were isolated to different neural responses, indicating that they may arise from independent attentional mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Controller Animation System

One of the ways in which computer animation can be generated is to use interactive graphics systems. In this paper we describe Controller, an animation system of this type. We concentrate on the operation of Controller and detail how an animator can plan and choreograph the motion of objects and cameras. We have intended to provide a system that gives the animator as much control as possible subject to keeping die interface simple to operate.     

Quality-of-life measures: Hospital interview versus home questionnaire.

Used measures adapted from social survey research to assess the quality of life of 33 18–55 yr old end-stage renal disease patients in a 2-wk test–retest design that varied both location and format of administration (hospital interview vs home self-administered questionnaire). Results indicate that quality of life is a stable construct and support the usefulness of questionnaire quality-of-life measures for evaluating medical interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)