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The design and performance of a room temperature electrical substitution radiometer for use as an absolute standard for measuring continuous-wave laser power over a wide range of wavelengths, beam diameters, and powers are described. The standard achieves an accuracy of 0.46% (k = 2) for powers from 10 mW to 100 mW and 0.83% (k = 2) for powers from 1 mW to 10 mW and can accommodate laser beam diameters (1/e2) up to 11 mm and wavelengths from 300 nm to 2 μm. At low power levels, the uncertainty is dominated by sensitivity to fluctuations in the thermal environment. The core of the instrument is a planar, silicon microfabricated bolometer with vertically aligned carbon nanotube absorbers, commercial surface mount thermistors, and an integrated heater. Where possible, commercial electronics and components were used. The performance was validated by comparing it to a National Institute of Standards and Technology primary standard through a transfer standard silicon trap detector and by comparing it to the legacy "C-series" standards in operation at the U.S. Air Force Metrology and Calibration Division (AFMETCAL). [ABSTRACT FROM AUTHOR]

Geoheritage sites can provide an excellent resource for sustainable development that represents a growing movement in Africa. Kobokwe Cave is formed within the Middle Proterozoic–aged sandstone of Kobokwe Gorge and is nationally important; the cave is the site where British missionary David Livingstone spent a night in 1847 and subsequently converted Kgosi (Chief) Kgari Sechele I, the first and only Christian “conversion” at that time by Livingstone. However, the site currently appears undervalued as there are little stewardship and minimal organized tourism and is affected by litter, graffiti, fires, illegal dumping and sand mining, and noise pollution from a nearby road; the building of the road itself destroyed a boulder of cultural significance. To test the level of environmental disturbance, the Karst Disturbance Index (KDI) was employed and this is the first known application to a non-carbonate karst environment and the first such application in Africa. Field observations were coupled with laboratory analyses of physico-chemical, nitrate, and heavy metal parameters in soil and water from the site. The final KDI score for Kobokwe of 0.29 is classed as showing “minor disturbance” and likely due to low visitor numbers although the sub-category of cultural disturbance scored 12 and is relatively high, as also found in previously published KDI studies from the USA, Italy, and Mexico. The analytical results are mostly at natural background levels, except for Pb in the cave floor soil (5.13 mg/L) and Pb in all water samples (0.3–0.63 mg/L) likely due to nearby vehicular traffic; also, Fe in all water samples (0.79–1.13 mg/L) that has possibly leached from the gorge sandstone and the spring water was slightly above standard background levels and possibly leached from nearby soil/rock. Future recommendations to avoid further disturbance and to promote environmental management of the site include community involvement, litter bin installation, graffiti removal, tour guides, information panels, entrance gate, tarred road, footpath installation, and enforcing of stronger site stewardship. [ABSTRACT FROM AUTHOR]

Multi-wall vertically aligned carbon nanotubes (VACNTs) are nearly ideal absorbers due to their exceptionally low reflectance over a broad wavelength range. Integrating VACNTs as bolometer absorbers, however, can be difficult due to their high growth temperature and fragile nature. Despite these challenges, we have microfabricated many different types of VACNT bolometers, ranging from cryogenic optical power primary standards to room temperature satellite-based solar irradiance monitors and broadband infrared microbolometers. Advantages our VACNT bolometers provide over the bolometers they replace vary by application, but can be reduced size and time constant, increased absorption, and/or microfabrication instead of hand assembly. Depending on the application and operating conditions, our VACNT bolometers are designed with a variety of thermistors and weak thermal links. The thermistors used include commercial surface mount chips, superconducting transition-edge sensors, and vanadium oxide (VOx). Weak thermal links include silicon nitride (SiNx) membranes, Si bridges, and laser-cut polyimide. We summarize a wide variety of microfabricated bolometers with VACNT absorbers that measure optical power levels spanning over seven orders of magnitude. [ABSTRACT FROM AUTHOR]

Background: Children of parents with mood and psychotic disorders are at elevated risk for a range of behavioral and emotional problems. However, as the usual reporter of psychopathology in children is the parent, reports of early problems in children of parents with mood and psychotic disorders may be biased by the parents' own experience of mental illness and their mental state. Methods: Independent observers rated psychopathology using the Test Observation Form in 378 children and youth between the ages of 4 and 24 (mean = 11.01, s.d. = 4.40) who had a parent with major depressive disorder, bipolar disorder, schizophrenia, or no history of mood and psychotic disorders. Results: Observed attentional problems were elevated in offspring of parents with major depressive disorder, bipolar disorder and schizophrenia (effect sizes ranging between 0.31 and 0.56). Oppositional behavior and language/thought problems showed variable degrees of elevation (effect sizes 0.17 to 0.57) across the three high-risk groups, with the greatest difficulties observed in offspring of parents with bipolar disorder. Observed anxiety was increased in offspring of parents with major depressive disorder and bipolar disorder (effect sizes 0.19 and 0.25 respectively) but not in offspring of parents with schizophrenia. Conclusions: Our results suggest that externalizing problems and cognitive and language difficulties may represent a general manifestation of familial risk for mood and psychotic disorders, while anxiety may be a specific marker of liability for mood disorders. Observer assessment may improve early identification of risk and selection of youth who may benefit from targeted prevention. [ABSTRACT FROM AUTHOR]

Six recently published language tests are examined in terms of theoretical models, choice of subtests, test format, reliability, norming population, and reporting scores. The tests are the Screening Test of Adolescent Language, the Word Test, the Test of Language Development-Intermediate, the Fullerton Language Tests for Adolescents, Clinical Evaluation of Language Functions-Diagnostic Battery, and Test of Adolescent Language. (CL)

As a group, the language impaired children demonstrated deficits in comprehension when compared to the normal language children. However, both groups scored near the ceiling on several tests, and on most tests that did differentiate the two groups, the mean scores of both groups were above the norms. (Author)