Cognitive psychology meets psychometric theory: On the relation between process models for decision making and latent variable models for individual differences.

This article analyzes latent variable models from a cognitive psychology perspective. We start by discussing work by Tuerlinckx and De Boeck (2005), who proved that a diffusion model for 2-choice response processes entails a 2-parameter logistic item response theory (IRT) model for individual differences in the response data. Following this line of reasoning, we discuss the appropriateness of IRT for measuring abilities and bipolar traits, such as pro versus contra attitudes. Surprisingly, if a diffusion model underlies the response processes, IRT models are appropriate for bipolar traits but not for ability tests. A reconsideration of the concept of ability that is appropriate for such situations leads to a new item response model for accuracy and speed based on the idea that ability has a natural zero point. The model implies fundamentally new ways to think about guessing, response speed, and person fit in IRT. We discuss the relation between this model and existing models as well as implications for psychology and psychometrics. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Phytosterols in human nutrition: Type,formulation, delivery,and physiological function

Phytosterols are a family of compounds similar to cholesterol which have been shown to lower cholesterol levels when supplemented in the diet. A daily dose of 2–3 g of phytosterols has been shown to reduce LDL‐cholesterol levels by 5–15%. Phytosterol supplementation can be undertaken using phytosterol enriched functional foods or nutraceutical preparations. The type of phytosterol supplemented, such as plant sterol or saturated plant stanol appear to be equally effective in lowering cholesterol levels. Phytosterols, whether in esterified or free form have both been shown to lower cholesterol levels, with esterified phytosterol formulations having a greater number of clinical trials demonstrating efficacy. The functional food or nutraceutical matrix which is used to deliver supplemental phytosterols can significantly affect cholesterol lowering efficacy. Effective cholesterol lowering by phytosterols depends on delivery of phytosterols to the intestine in a form which can compete with cholesterol for absorption. New phytosterol functional food and nutraceuticals products should always be tested to demonstrate adequate delivery of phytosterol dose and effective total and LDL‐cholesterol lowering. Phytosterol products which do not effectively lower cholesterol will negatively impact the perception and use of phytosterols, and must not be allowed on the marketplace.     

A single-switch AC/DC converter with voltage regulated storage capacitor

A single-stage power-factor-corrected AC/DC converter (SSPFC) usually causes high voltage stress on the intermediate storage capacitor, due to the lack of control of this voltage. The storage capacitor voltage varies largely with line voltage, and load current and is usually higher than the peak line voltage. This paper presents a new single-switch SSPFC based on a flyback topology for which the storage capacitor voltage is loosely regulated by the output voltage. Without using extra power switches to increase the control dimension, the proposed converter uses a flyback converter with dual-output transformer to achieve the control purpose. The range of storage capacitor voltage change against the change of input voltage and load current is significantly reduced. Moreover, the maximum storage capacitor voltage can stay below the peak line voltage at high line condition. Experimental results verifying the operation of the proposed SSPFC are also reported.     

In Situ Cube-Corner Indentation of Soda–Lime Glass and Fused Silica

Indentation fracture with a cube-corner diamond pyramid on soda–lime silicate glass and fused silica is investigated during the entire indentation cycle in both silicone oil and ambient-air environments. Radial cracks form immediately on loading in all cases. The two-component, elastic-contact + elastic-plastic mismatch (residual) stress field model that has been used successfully to describe radial crack evolution at Vickers indentations fails to describe the fracture response with the cube-corner. The amplitudes of both elastic-contact and residual stress-intensity factors as deduced from these cube-corner experiments are up to a factor of 10 greater than have been previously observed.     

When does between-sequence phonological similarity promote irrelevant sound disruption?

Typically, the phonological similarity between to-be-recalled items and TBI auditory stimuli has no impact if recall in serial order is required. However, in the present study, the authors have shown that the free recall, but not serial recall, of lists of phonologically related to-be-remembered items was disrupted by an irrelevant sound stream (end rhymes) sharing similar phonological content. These findings can be explained by the notion that between-sequence phonological similarity effects emerge when category-cueing processes become an important determinant for recall, such as when shared category information can be used as a retrieval aid to cue list items or plausible list candidates. In this case, the presence of categorically similar irrelevant items impairs the retrieval of list items and leads to intrusion error. Implications of these results for theories of auditory distraction are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis, Characterization and Conductivity of Quaternary Nitrogen Surfactants Modified by the Addition of a Hydroxymethyl Substructure on the Head Group

Two novel series of hydroxymethyl group-appended quaternary nitrogen surfactants (QNSs) based on the aliphatic N-alkyl-trimethylammonium and aromatic N-alkylpyridinium head groups were synthesized from the appropriate nitrogen head group precursor and 1-bromoalkane. The QNSs were characterized using ¹H and ¹³C nuclear magnetic resonance and infrared spectroscopy, and their purity confirmed using elemental analysis. The solution behavior of the QNSs was investigated by conductivity, assessing both the aggregation concentration as well as the amount of counter-ion dissociation. The results showed a general decrease in the aggregation concentration for the compounds with the hydroxymethyl addition, where the pyridinium compounds were more affected than the ammonium QNSs. In contrast, the extent of counter-ion dissociation (??) from the aggregate was slightly increased for the ammonium compounds but that of the pyridinium compounds was not generally affected by the structural modification.     

The Temporal Mechanisms Guiding Interneuron Differentiation in the Spinal Cord

Neurogenesis timing is an essential developmental mechanism for neuronal diversity and organization throughout the central nervous system. In the mouse spinal cord, growing evidence is beginning to reveal that neurogenesis timing acts in tandem with spatial molecular controls to diversify molecularly and functionally distinct post-mitotic interneuron subpopulations. Particularly, in some cases, this temporal ordering of interneuron differentiation has been shown to instruct specific sensorimotor circuit wirings. In zebrafish, in vivo preparations have revealed that sequential neurogenesis waves of interneurons and motor neurons form speed-dependent locomotor circuits throughout the spinal cord and brainstem. In the present review, we discuss temporal principals of interneuron diversity taken from both mouse and zebrafish systems highlighting how each can lend illuminating insights to the other. Moving forward, it is important to combine the collective knowledge from different systems to eventually understand how temporally regulated subpopulation function differentially across speed- and/or state-dependent sensorimotor movement tasks.     

Does a helping hand mean a heavy heart? Helping behavior and well-being among spouse caregivers.

Being a caregiver for an ill or disabled loved one is widely recognized as a threat to the caregiver’s quality of life. Nonetheless, research indicates that helping behavior, broadly construed, promotes well-being. Could helping behavior in a caregiving context promote well-being as well? In the present study, we used ecological momentary assessment to measure active helping behavior and both positive and negative affect in 73 spouse caregivers. Results indicate that when controlling for care recipient illness status and functional impairment and caregiver “on call” caregiving time, active helping predicted greater caregiver positive affect—especially for individuals who perceived themselves as interdependent with their spouse. In addition, although both helping and on-call time predicted greater negative affect for caregivers who perceived low interdependence, helping was unrelated to negative affect among caregivers perceiving high interdependence. Helping valued loved ones may promote caregivers’ well-being. (PsycINFO Database Record (c) 2010 APA, all rights reserved)