Modulation of Mechanical Interactions by Local Piezoelectric Effects

Piezoelectricity is a well‐established property of biological materials, yet its functional role has remained unclear. Here, a mechanical effect of piezoelectric domains resulting from collagen fibril organisation is demonstrated, and its role in tissue function and application to material design is described. Using a combination of scanning probe and nonlinear optical microscopy, a hierarchical structuring of piezoelectric domains in collagen‐rich tissues is observed, and their mechanical effects are explored in silico. Local electrostatic attraction and repulsion due to shear piezoelectricity in these domains modulate fibril interactions from the tens of nanometre (single fibril interactions) to the tens of micron (fibre interactions) level, analogous to modulated friction effects. The manipulation of domain size and organisation thus provides a capacity to tune energy storage, dissipation, stiffness, and damage resistance.     

Faking and personality assessment in personnel selection: Advancing models of faking.

Personality testing is a particularly valuable preemployment assessment tool when one matches personality traits to job requirements. The authors explain that, unlike most other common personnel selection methods, the unique value of personality assessment in personnel selection stems from its tendency to predict the choice to perform, or “will-do” aspects of job performance. The effect of faking on the value of personality testing is discussed, and the authors suggest that personality testing’s contribution to personnel selection could be leveraged if more were known about the psychological process underlying applicant faking behaviour. To this end, the authors present an improved general model of the applicant faking process as well as a new “faking decision tree.” (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Conduction of Current in Bearings

The mechanism of the action of sulfur compounds during boundary lubrication has been studied by using S³⁵ as a tracer. A NACA type friction machine was used to study the chemical reaction between elementary sulfur or sulfur compounds and metals. All additives were added to cetane which was used as a lubricating oil.

It has been found that it is possible to study kinetically the formation of the iron sulfide and the rate of the wear of its film on the friction surface. Some good analytical results have been obtained.

The rate of wear of iron sulfide film for benzyl disulfide is lower than that for the elementary sulfur, because the former may adsorb effectively to the worn surface. The iron sulfide film formed on the friction surface seems to absorb the polar compounds more actively than the surface of iron oxide. These results Were revealed from the autoradiography of the adsorption.     

Convex piecewise-linear fitting

We consider the problem of fitting a convex piecewise-linear function, with some specified form, to given multi-dimensional data. Except for a few special cases, this problem is hard to solve exactly, so we focus on heuristic methods that find locally optimal fits. The method we describe, which is a variation on the K-means algorithm for clustering, seems to work well in practice, at least on data that can be fit well by a convex function. We focus on the simplest function form, a maximum of a fixed number of affine functions, and then show how the methods extend to a more general form.     

Modeling the energy potential of biomass – H2RES

Modeling biomass as a renewable energy source poses many challenges with respect to feedstock variability, which are difficult to account for. It is found that at the preliminary stages of energy planning, heating value and moisture content of the feedstock are the most important factors. In addition, the effects of harvesting, transportation and storage are found to be significant even though they are often overlooked. Using the gathered information a biomass module for energy planning is created and integrated to H₂RES, a renewable energy planning program. Using this excel based software, a case study for a wood processing factory is performed, using the waste wood as feedstock. Comparing various scenarios, it is concluded that using a combination of solid oxide fuel cells, solar panels and steam turbines can satisfy the factories energy requirements with excess sold to the grid.     

Reduced insulin-like growth factor-I after acute feed restriction in lactating dairy cows is independent of changes in growth hormone receptor 1A mRNA

Growth hormone receptor (GHR) and insulin-like growth factor-I (IGF-I) mRNA decrease in the liver of dairy cows at parturition. Epinephrine is released and feed intake is decreased at the same time. The objective of this study was to determine whether feed restriction and (or) administration of epinephrine could recapitulate the changes in the hepatic GHR 1A and IGF-I mRNA that occur at parturition. Eight lactating cows were randomly assigned to one of two rations (ad libitum or restricted). The cows assigned to the restricted ration were fed 75, 60, 60, and 25% of feed consumed by the ad libitum cows on successive days to mimic the changes in feed intake around parturition. Liver samples were collected by needle biopsy before and after feed restriction. Cows received either 0.02 mg/kg of epinephrine or saline approximately 24 h before the second liver biopsy so that a 2 x 2 factorial arrangement of treatments was created. Feed restriction increased plasma nonesterified fatty acids and liver triglyceride percentages and decreased plasma IGF-I concentrations. The decrease in plasma IGF-I after feed restriction was associated with a decrease in IGF-I mRNA in feed-restricted cows. The amount of GHR 1A mRNA did not change after feed restriction. Epinephrine treatment did not affect the amount of GHR 1A or IGF-I mRNA. We conclude that the decrease in feed intake at parturition may be partially responsible for the decrease in IGF-I but may not cause the decrease in GHR 1A.     

Human placental amino acid transporter genes: expression and function

Recent findings on amino acid transporter genes are reviewed with particular focus on matching previously described transport systems to individual genes. Functional studies using cloned and expressed transporters are considered as the critical tool allowing identification of the functional properties of individual genes. Specifically, these experiments allow identification of the transported substrate amino acids and of the transport mechanism. We focus on the very recent discovery and properties of the heterodimeric family of amino acid transport proteins where two subunits encoded in different genes are required. For these transporters, co-expression of both subunits is mandatory for functional studies. The field of placental amino acid transport is further complicated by complexities arising from both gestational age-specific and species-specific gene expression. The function of the transporter also depends on its cellular localization in the trophoblast. In addition, for transporters that are coupled to ion gradients, both membrane potential and ion pumping will contribute to the rate of amino acid delivery to the fetus. Regulation of function is important not only for fetal nutrition but also for specific additional aspects of placental biology.