Proton-exchanged optical waveguides in Y-cut lithium niobate

The fabrication of proton exchanged monomode optical waveguides on Y-cut lithium niobate is reported. Molten benzoic acid is used, but damage of the crystal surface is avoided.     

Simplified method of eliminating the effect of nonlinearities on process crosscorrelations

A modified msequence is proposed to simplify the instrumentation in using the Gardiner method of identifying the linear channel of a nonlinear process. The class of sequence has properties suited to multivariate crosscorrelation.     

Adaptive control of time-varying linear systems

The authors present a global bounded-input-bounded-state stability theory for a class of continuously adapting controllers applied to time-varying linear systems. This gives theoretical support to the application of many of the algorithms used in practice. A key feature of the analysis is that no persistence of excitation requirement is needed     

Convergence properties of the Riccati difference equation in optimal filtering of nonstabilizable systems

This paper studies the convergence and properties of the solutions of the Riccati difference equation. Special emphasis is given to systems which are not necessarily stabilizable (in the filtering sense), particularly those having uncontrollable roots on the unit circle. Besides generalizing and unifying previous work, the results have application to a number of important problems including filtering and control of systems with purely deterministic disturbances such as sinusoids and drift components.     

Epileptic aphasia: a consequence of regional hypometabolic encephalopathy?

A series of 25 children, 13 females and 12 males, who had an acquired communication disorder together with epilepsy, but did not fulfil the strict criteria of the Landau-Kleffner syndrome, was studied. All children had a clinical neurological evaluation, speech and language assessment, an awake and sleep EEG, cranial MRI, SPET scan, and audiometry. Clinical seizures were most often polymorphic in type (17 of 25). Atypical absences were the commonest individual seizure type occurring in 15 cases. All patients had an unequivocal epileptiform EEG. Normal sleep phenomena were only observed in 10 cases, enhancement of epileptiform activity in sleep was seen in 16. Cranial MRI was abnormal in six and normal in 19 cases. The SPET scans were abnormal in 22 of 25 children. The language deficits were classified neurologically as receptive aphasia, 24 of 25; expressive aphasia, 20 of 25; nominal aphasia, eight of 25; articulatory dyspraxia, 10 of 25; and auditory agnosia, nine of 25. It is hypothesized that the loss of communication skills is due to an encephalopathy secondary to the persistent epileptic discharge and manifests as a hypometabolic area on the SPET scan.     

Temporal trends in coal workers' pneumoconiosis prevalence. Validating the National Coal Study results

Evidence from four successive rounds of the National Study of Coal Workers' Pneumoconiosis indicates diminishing prevalence of coal workers' pneumoconiosis (CWP) from 1969 to 1988. However, methodological inconsistencies across surveys have raised concerns. This study confirms the reported downward trend in CWP prevalence, utilizing a standardized methodological approach. A single team of three x-ray readers using the 1980 International Labour Office classification independently re-evaluated 3143 Appalachian-region cases to derive overall, tenure- and age-specific prevalences. Prevalence of small rounded opacities declined, with 12.7% in Round 1, 11.2% in Round 2, 3.0% in Round 3, and 3.9% in Round 4. These findings support the National Institute for Occupational Safety and Health's recommendation of a reduced exposure limit of 1 mg/m3 because the present coal dust standard does not sufficiently protect miners against adverse health effects over a working lifetime of exposures.     

The system development corporation and system training.

The RAND Corporation established a laboratory to conduct an interdisciplinary investigation of human factors in man-machine systems. RAND from 1951 to 1954 conducted a number of studies related to an Air Defense Direction Center (radar-site) concerning "a system that not only processes incoming information, but also makes crucial decisions based on interpretations of it." It was possible, on the basis of hypotheses generated and tested in the laboratory, to make some rather detailed predictions about system learning. A somewhat simplified schematic diagram of a system is presented. Various psychological skills important to STP (Systems Training Program) are briefly described. The "rapid growth of automation techniques presents a real challenge for psychologists, guaranteeing a most exciting future for those who care to meet it." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interstitial cystitis in adolescent girls

Two cases of interstitial cystitis with typical, large bladder ulcerations in adolescent girls are reported. The specific diagnosis was confirmed histologically after full-thickness segmental resection of the bladder wall at the site of the ulceration during subsequent operations. Contrary to other reports based on subjective clinical findings, interstitial cystitis in children is rare when rigid criteria, including careful histological study, are applied. Treatment in children is the same as in adults and should be conservative. A conscientious attempt should be made to exclude infection and tuberculosis as possible contributors to the symptoms of urinary frequency and discomfort, as well as other causes of bladder abnormality. If conservative management fails to relieve symptoms the bladder may be enlarged in some cases by using a segment of intestine.