Factor analysis of the Mayo-Portland Adaptability Inventory: structure and validity

Principal-components (PC) factor analysis of the Mayo-Portland Adaptability Inventory (MPAI) was conducted using a sample of outpatients (n = 189) with acquired brain injury (ABI) to evaluate whether outcome after ABI is multifactorial or unifactorial in nature. An eight-factor model was derived which explained 64-4% of the total variance. The eight factors were interpreted as representing Activities of Daily Living, Social Initiation, Cognition, Impaired-Self-awareness/Distress, Social Skills/ Support, Independence, Visuoperceptual, and Psychiatric, respectively. Validation of the Cognition factor was supported when factor scores were correlated with various neuropsychological measures. In addition, 117 patient self-rating total scores were used to evaluate the Impaired Self-awareness/Distress factor. An inverse relationship was observed, supporting this factor's ability to capture the two-dimensional phenomena of diminished self-awareness or enhanced emotional distress. A new subscale structure is suggested, that may allow greater clinical utility in understanding how ABI manifests in patients, and may provide clinicians with a better structure for implementing treatment strategies to address specific areas of impairment and disability for specific patients. Additionally, more precise measurement of treatment outcomes may be afforded by this reorganization.     

Mayo cognitive factors scales: Derivation of a short battery and norms for factor scores.

G. E. Smith et al (see PA, Vol 80:4129 and 24183) confirmed that 5 factors underlie the covariance structure of a core battery of the Wechsler Adult Intelligence Scale—Revised (WAIS—R), Wechsler Memory Scale—Revised (WMS—R), and Auditory Verbal Learning Test administered to the Mayo's Older Americans Normative Studies sample and to an independent clinical sample. In the present study, full factor scores generated by this 5-factor model were used as criterion variables in the development of a short battery. It was determined that 16 of the 24 subtests were sufficient to explain substantial variance in the 5 factor scores. However, 1 additional immediate memory subtest must be administered as a prelude to a delayed recall test. Thus, a collection of 17 subtests are offered as a short battery for older persons. Norms for the calculation of Mayo Cognitive Factor Scales scores are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maintenance Techniques in Distributed Communications Switching Systems

The reliability and maintainability design criteria that were a part of large central-control communication systems, have been combined to produce deferred maintenance concepts in fully distributed communication systems. Combining these concepts allows the achievement of a cost-effective life-cycle design for communication switching systems. In a hardware/software environment one should not separate hardware maintainability and software maintainability, nor separate the reliability and maintainability of the system. Reliability models are being developed that reflect a constant rate for transient faults and a decreasing rate for catastrophic faults. The relationship of software bugs to their number and type of manifestation is being defined. Designs for primarily non-attended system sites should include appropriate maintenance concepts in order to be cost effective. If two or more individual repairs can be made with each maintenance visit to a site, the total area maintenance staff can be reduced. Implementation of deferred maintenance techniques can raise the availability level of the services provided, especially for a distributed communication switching system. Several examples of practical techniques for developing deferred maintenance concepts are presented, and topics such as the manning versus non-manning of sites, the time of day effects on state diagrams, centralized maintenance, and computer modeling techniques are discussed. The current and potential maintainability concepts and analysis tools that are discussed in this paper can be used to develop cost-effective maintenance concepts as distributed systems become more prevalent.     

Clusters of impaired normal elderly do not decline cognitively in 3 to 5 years.

The ability of clusters of psychometric profiles to predict cognitive decline 3 to 5 years later was examined. Using Ward's method, researchers conducted cluster analysis of age- and education-corrected Mayo Cognitive Factor Scale (MCFS) scores obtained at first evaluation for 376 normal elderly. Results revealed 4 of 16 cluster profiles were predicted to represent at-risk status for future cognitive decline; 258 of the original sample completed psychometric reassessment. Membership in an at-risk cluster did not powerfully predict subsequent medical evaluation of cognitive or psychiatric disorder or status as lost to follow-up. Repeated measures analyses of variance of MCFS scores showed no differential decline in learning or memory between normal and at-risk clusters. Thus, in a nonclinical sample, relative cognitive impairments are not powerfully predictive of future cognitive decline. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

New method of view factor calculation in radiative transfer

The method of view factor calculation presented in this article is based on the methods of analytical geometry. The given method can be used when the surfaces are separated by non-absorbing gas and radiation from the surfaces, whether emitted or reflected, is diffused.     

Performance measurement and test techniques for modern AM broadcasttransmitters

The numerous tests required in evaluating the performance of a modern AM transmitter are discussed. Both laboratory tests of novel products and environmental tests are covered. The latest attainable performance measurements, environmental testing requirements, and field condition simulation tests are examined