Diffusion-controlled chronoamperometry at a disk electrode

An accurate formula exists for describing the decay of the current following the imposition of extreme concentration polarization on a disk electrode under diffusion-controlled conditions. It has been amply validated by diverse simulations and is presented here in a more compact form than hitherto. The formula finds application beyond the realm of potential-step chronoamperometry.     

Bose-Einstein condensates and precision measurements

An ongoing challenge in physics is to make increasingly accurate measurements of physical quantities. Bose-Einstein condensates in atomic gases are ideal candidates for use in precision measurement schemes since they are extremely cold and have laser-like coherence properties. In this paper, we review these two attributes and discuss how they could be exploited to improve the resolution in a range of different measurements.     

Nanoscale, phonon-coupled calorimetry with sub-attojoule/Kelvin resolution

We have developed an ultrasensitive nanoscale calorimeter that enables heat capacity measurements upon minute, externally affixed (phonon-coupled) samples at low temperatures. For a 5 s measurement at 2 K, we demonstrate an unprecedented resolution of DeltaC approximately 0.5 aJ/K ( approximately 36 000 k(B)). This sensitivity is sufficient to enable heat capacity measurements upon zeptomole-scale samples or upon adsorbates with sub-monolayer coverage across the minute cross sections of these devices. We describe the fabrication and operation of these devices and demonstrate their sensitivity by measuring an adsorbed (4)He film with optimum resolution of approximately 3 x 10(-5) monolayers upon an active surface area of only approximately 1.2 x 10(-9) m(2).     

A three-parameter mechanical property reconstruction method for MR-based elastic property imaging

A reconstruction process featuring full parameterization of the three dimensional, time-harmonic equations of linear elasticity is developed and reconstructed property images are presented from simulation-based investigation. While interesting in its own right through the potential for increased adaptability of these reconstructive elastic imaging techniques, this study also presents a set of analysis tools used to study the poor convergence behavior found in the case of tissue like conditions (i.e. nearly incompressible materials). The choice of elastic properties for imaging in elastography research remains an open question at this point; the use of the stability and sensitivity-based analytical methods described here will help to predict and understand the value and reliability of different parameterizations of elasticity imaging. Additionally, though results indicate significant work needs to be done to achieve effective multiparameter reconstructive imaging, the methods detailed here offer the promise of increased flexibility and sophistication in elastographic imaging techniques.     

Nitrogen pools and fluxes in grassland soils sequestering carbon

Carbon sequestration in agricultural, forest, and grassland soils has been promoted as a means by which substantial amounts of CO₂ may be removed from the atmosphere, but few studies have evaluated the associated impacts on changes in soil N or net global warming potential (GWP). The purpose of this research was to (1) review the literature to examine how changes in grassland management that affect soil C also impact soil N, (2) assess the impact of different types of grassland management on changes in soil N and rates of change, and (3) evaluate changes in N₂O fluxes from differently managed grassland ecosystems to assess net impacts on GWP. Soil C and N stocks either both increased or both decreased for most studies. Soil C and N sequestration were tightly linked, resulting in little change in C:N ratios with changes in management. Within grazing treatments N₂O made a minor contribution to GWP (0.1–4%), but increases in N₂O fluxes offset significant portions of C sequestration gains due to fertilization (10–125%) and conversion (average = 27%). Results from this work demonstrate that even when improved management practices result in considerable rates of C and N sequestration, changes in N₂O fluxes can offset a substantial portion of gains by C sequestration. Even for cases in which C sequestration rates are not entirely offset by increases in N₂O fluxes, small increases in N₂O fluxes can substantially reduce C sequestration benefits. Conversely, reduction of N₂O fluxes in grassland soils brought about by changes in management represents an opportunity to reduce the contribution of grasslands to net greenhouse gas forcing.     

Copper Chaperone for Cu/Zn Superoxide Dismutase is a sensitive biomarker of mild copper deficiency induced by moderately high intakes of zinc

Background  

Small increases in zinc (Zn) consumption above recommended amounts have been shown to reduce copper (Cu) status in experimental animals and humans. Recently, we have reported that copper chaperone for Cu/Zn superoxide dismutase (CCS) protein level is increased in tissues of overtly Cu-deficient rats and proposed CCS as a novel biomarker of Cu status.     

Psychological processes and mental states.

Comments on D. Kipnis's (see record 199707781-001) article that argues against the use of psychological processes as a basis for the explanation of social behavior. The present author concerns himself with Kipnis's use of "psychological processes" and "mental states" as synonyms. He claims that Kipnis overstepped his argument by generalizing his conclusion from the term "mental states" to "psychological processes." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maternal IQ and home environment as determinants of early childhood intellectual competence: A developmental analysis.

Children at risk for sociocultural mental retardation were studied longitudinally from birth to 4 yrs of age. Maternal IQs were assessed before the children's births, and children's IQs and home environments were assessed at regular intervals during the 1st 4 yrs of life. Multiple regression analyses were conducted to separate the contributions of maternal IQ and home environment to child IQ at 24, 36, and 48 mo. When the effect of maternal IQ was controlled, home environment's association with child IQ was significant only at 48 mo. When the effect of home environment was controlled, maternal IQ's association with child IQ was significant only at 24 mo. Taken together, the 2 predictors explained 11, 17, and 29% of the variance in child IQ at the 3 respective times. The overall pattern suggested a monotonic increase in the predictability of child IQ within the context of a shift in the relative importance of maternal IQ and home environment as predictors. The integration of the study of behavioral genetics with the study of the process of intellectual development requires an ontogenetic perspective. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On scheduling in a GT environment

Traditional research in scheduling has concentrated on developing optimal and optional tending heuristic algorithms for n x m job shop and flow shop problems. Relatively no work has been conducted in the area of scheduling within a GT cell. This paper examines the GT cell environment from a scheduling perspective in relation to a job and flow shop, and presents a modified approach to scheduling within a GT cell that implicitly takes advantage of common setups and part family coding structures.