Restoring Colorado River Ecosystems: A Troubled Sense of Immensity

This report examines the TIGER system and related products to help planners understand the basic concepts underlying the system and its relevance for planning. The report first introduces the TIGER system, pointing out what it is—and what it is not. The second section examines the unique and powerful way geographic data are stored in the TIGER system that allow it to deal with topology—the spatial relationship between points and lines on a map. The third section examines the TIGER/Line® data files, the first and potentially most important TIGER data released to the public. The fourth considers some of the ways the TIGER/Line data can be used in planning. The fifth examines several software packages that can be used with the TIGER/Line files. The final section evaluates the TIGER system and considers its future role in planning.     

扩大ARM SOC的验证覆盖缩短仿真时间

验证复杂的SoC设计要耗费极大的成本和时间。据证实，验证一个设计所需的时间会随着设计大小的增加而成倍增加。在过去的几年中，出现了很多的技术和工具，使验证工程师可以用它们来处理这类问题。但是，这些技术中很多基于动态仿真，并依靠电路操作来发现设计问题，因此设计者仍面临为设计创建激励的问题。     

A hybrid digital/RF envelope predistortion linearization system for power amplifiers

This paper presents an adaptive wide-band digitally controlled RF envelope predistortion linearization system for power amplifiers (PAs). A field-programmable gate-array-based lookup table is indexed by a digitized envelope power signal, and instantaneously adjusts the input signal amplitude and phase via an RF vector modulator to compensate for the AM-AM and AM-PM distortion. The advantages of this predistortion architecture over conventional baseband digital approaches are that a 20%-33% wider correction bandwidth is achievable at the same clock speeds, and linearization can be performed without the need for a digital baseband input signal. The timing match between the input RF signal and predistorting signal, which is one of the critical factors for performance, was investigated and adjusted to obtain optimum performance. Using three-carrier cdmaOne and wide-band multitone signals, the linearization performances for a 0.5-W GaAs heterostructure field-effect transistor, a 90-W peak-envelope-power (PEP) silicon LDMOS PA, and a 680-W PEP LDMOS PA were examined. In addition, the predistortion performance variation for different signals was studied in terms of signal envelope statistics, output powers, and PA power capacities.     

Quantification of force abnormalities during passive andactive-assisted upper-limb reaching movements in post-stroke hemiparesis

We evaluated a method for measuring abnormal upper-limb motor performance in post-stroke hemiparetic subjects. A servomechanism (MIME) moved the forearm in simple planar trajectories, directly controlling hand position and forearm orientation. Design specifications are presented, along with system performance data during an initial test of 13 stroke subjects with a wide range of impairment levels. Performance of subjects was quantified by measuring the forces and torques between the paretic limb and the servomechanism as the subjects relaxed (passive), or attempted to generate force in the direction of movement (active). During passive movements, the more severely impaired subjects resisted movement, producing higher levels of negative work than less-impaired subjects and neurologically normal controls. During active movements, the more severely impaired subjects produced forces with larger directional errors, and were less efficient in producing work. These metrics had significant test-retest repeatability. These motor performance metrics can potentially detect smaller within-subject changes than motor function scales. This method could complement currently used measurement tools for the evaluation of subjects during recovery from stroke, or during therapeutic interventions.     

Language disorders and learning disabilities in school-refusing adolescents

OBJECTIVE: We undertook this study to test the hypothesis that school-refusing adolescents hospitalized on an inpatient psychiatric unit have more language and learning disabilities than diagnosis-, age-, and sex-matched psychiatric controls. METHOD: The Woodcock-Johnson Tests of Achievement-Revised (WJTA-R), the WISC-R, the Adolescent Language Screening Test, the Clinical Evaluation of Language Fundamentals-Revised, and the Test of Language Competence (TLC) were given to a group of well-characterized, primarily depressed school refusers and matched psychiatric controls. RESULTS: We found that school-refusing adolescents had significantly lower WISC-R verbal intelligence scores, lower Math and Written Language subscale scores on the WJTA-R, and lower scores on the TLC than nonrefusers. School refusers were found to have a significantly higher incidence of both language impairments and learning disabilities than controls. CONCLUSIONS: We infer that academic and communicative frustration and the adolescent's resulting inability to meet the academic and social demands in the school environment may play a role in the etiology of school refusal.