Validating the use of channels to estimate the ideal linear observer

Image quality can be objectively defined according to how well an observer can perform a task of practical interest given the image. We review a practical model observer for the signal-detection task. The ideal observer for this task is a function of the image probability distributions, which are multidimensional and complicated. This observer is often too difficult to derive or estimate. An alternative to the ideal observer is the ideal linear observer, which can still be unmanageable. Our alternative is the ideal linear observer constrained to a small set of channels: the channelized-Hotelling observer.     

Updated Correlation Between Aircraft Smoke Number and Black Carbon Concentration

Aircraft emissions of black carbon (BC) contribute to anthropogenic climate forcing and degrade air quality. The smoke number (SN) is the current regulatory measure of aircraft particulate matter emissions and quantifies exhaust plume visibility. Several correlations between SN and the exhaust mass concentration of BC (C _BC) have been developed, based on measurements relevant to older aircraft engines. These form the basis of the current standard method used to estimate aircraft BC emissions (First Order Approximation version 3 [FOA3]) for the purposes of environmental impact analyses. In this study, BC with a geometric mean diameter (GMD) of 20, 30, and 60 nm and filter diameters of 19 and 35 mm are used to investigate the effect of particle size and sampling variability on SN measurements. For BC with 20 and 30 nm GMD, corresponding to BC emitted by modern aircraft engines, a smaller SN results from a given C _BC than is the case for BC with 60 nm GMD, which is more typical of older engines. An updated correlation between C _BC and SN that accounts for typical size of BC emitted by modern aircraft is proposed. An uncertainty of ±25% accounts for variation in GMD in the range 20–30 nm and for the range of filter diameters. The SN–C _BC correlation currently used in FOA3 underestimates by a factor of 2.5–3 for SN ≤15, implying that current estimates of aircraft BC emissions derived from SN are underestimated by the same factor.

Copyright 2013 American Association for Aerosol Research     

Ovine arylalkylamine N-acetyltransferase in the pineal and pituitary glands: differences in function and regulation

The enzyme arylalkylamine N-acetyltransferase (AANAT; EC 2.3.1.87) has been conventionally linked with the biosynthesis of melatonin within the pineal gland and retina. This study establishes that AANAT messenger RNA (mRNA) and functional enzyme occurs within the pars tuberalis (PT) and to a lesser degree within the pars distalis (PD) of the sheep pituitary gland; expression in these tissues is approximately 1/15th (PT) and 1/300th (PD) of that in the ovine pineal gland. AANAT mRNA in the PT appears to be expressed in the same cells as the Mel1a receptor. No evidence was obtained to indicate that either PT or PD cells have the ability to synthesize melatonin, suggesting that this enzyme plays a different functional role in the pituitary. We also found that cAMP regulation of the abundance of AANAT mRNA differs between the PT and pineal gland. Forskolin (10 microM) has no effect on pineal AANAT mRNA levels, yet represses expression in the PT. This suppressive influence could be mediated by ICER (inducible cAMP response early repressor), which is induced by forskolin in both tissues. Although it appears that the specific function and regulation of AANAT in the pituitary gland differ from that in the pineal gland, it seems likely that AANAT may play a role in the broader area of signal transduction through the biotransformation of amines.     

Thermodynamic and Kinetic Effects of Oxygen Removal on the Thermal Conductivity of Aluminum Nitride

High thermal conductivity, low dielectric constant, high electrical resistivity, low density, and a thermal expansion coefficient that matches well with that of silicon are the principal attributes of AIN that have attracted much attention over the past decade. It is also now well established that oxygen as an impurity lowers the thermal conductivity of AIN. Processing techniques have been developed which not only facilitate pressureless densification of AIN but also enhance its thermal conductivity. The present work explores the thermodynamics and the kinetics of oxygen removal and the resultant enhancement of thermal conductivity. Polycrystalline AIN ceramics were fabricated with Y₂O₃, Dy₂O₃, Yb₂O₃, CaO, BaO, or MgO as additives. Samples were sinter/annealed at 1850°C for up to 1000 min. The AIN grain size of sintered samples ranged between 2 and 9 μm. The samples typically contained two or three phases with the predominant phase being AIN. Secondary phases in Y₂O₃-doped AIN consisted of yttrium aluminates which were along three grain junctions and along grain facets. The presence of Y₃Al₅O₁₂, YAIO₃, and Y₄Al₂O₉, as well as Y₂O₃, depending upon the Y₂O₃/Al₂O₃ ratio, was revealed by X-ray diffraction. Thermal conductivity increased with the amount of additive and annealing time. Thermal conductivity also depended on the type of additive. Samples with thermal conductivity up to 200 W/(m · K) were fabricated. The variation in thermal conductivity with the type and the amount of the additive is explained on the basis of the thermodynamics of oxygen removal. In particular, the higher thermal conductivity of CaO-doped, in comparison with MgO-doped, samples is rationalized on the basis that the free energy of formation, ΔG°, of CaAl₂O₄ is less than that of MgAl₂O₄. It is proposed that the higher the |ΔG°|, with ΔG° < 0, the higher is the resultant thermal conductivity. An increase in the thermal conductivity with annealing time is attributed to the kinetics of oxygen removal from AIN grains.     

"Controlling teaching strategies: Undermining children's self-determination and performance": Correction to Flink et al.

Reports an error in "Controlling teaching strategies: Undermining children's self-determination and performance" by Cheryl Flink, Ann K. Boggiano and Marty Barrett (Journal of Personality and Social Psychology, 1990[Nov], Vol 59[5], 916-924). In the article, Figure 1 on page 922 is labeled incorrectly. The labels in both the left and right panels of the figure should be reversed so that No Pressure Condition is the label for the broken lines and Pressure Condition is the label for the solid lines. The following abstract of the original article appeared in record 1991-13808-001.) Examined the hypothesis that students would show performance impairment when they were exposed to teachers who were pressured to maximize student performance level and who used controlling strategies. For this purpose, 4th-grade teachers and their students participated in a field experiment in which teachers either were pressured to maximize student performance or were told simply to help their students learn. In addition, the teaching sessions were videotaped to assess teachers' use of controlling strategies, as rated by blind coders. Following the teaching sessions, student performance on tasks initially taught by teachers as well as on a generalization task was assessed by blind experimenters. As predicted, the data indicated that students evidenced performance impairment during the subsequent testing session only when they were exposed to pressured teachers using controlling strategies. Results are discussed within the context of self-determination theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

COLLAGEN CHEMISTRY IN RELATION TO ISINGLASS AND ISINGLASS FININGS. PART II

The intrinsic viscosities of collagen finings were higher in the absence of citrate buffer than in its presence. The lower values, which vary among different preparations, well reflect their relative fining abilities. The latter are due to molecules which are, in most cases, larger than monomers, and the differences in intrinsic viscosity are ascribed to differences in molecular structure in the original tissues. The higher values observed in the absence of citrate are due to the aggregation of these molecules; however, these dissociate in beer and so do not assist fining in this form. The effect of the rate of flow in the viscosity measurements is considered. Differences in the shrinkage temperature of isinglass are related to differences in macrostructure, but these are not necessarily related to the stability of the protein in solution. The denaturation temperatures (T_D° C) of all the finings examined were in the range 29·2–30·3° C.     

Evaluation of Mangosteen juice blend on biomarkers of inflammation in obese subjects: a pilot, dose finding study

Background  

The ability to reduce inflammation in overweight and obese individuals may be valuable in preventing the progression to metabolic syndrome with associated risks for heart disease and diabetes. The purpose of this study was to evaluate the effect of multiple dosages of a proprietary Mangosteen Juice blend on indicators of inflammation and antioxidant levels in obese patients with elevated C-reactive protein (CRP) levels.