The generalized Kuhn model of linear viscoelasticity

We propose a generalization of the Kuhn model of linear viscoelasticity. This generalization, which has four material parameters, is able to provide a near frequency independent response over a wide range of frequencies. It is useful for highly dissipative materials such as asphalt concrete. It is derived by generalizing Lubliner and Panoskaltsis’s modified Kuhn model, but we also show that it is closely related to fractional derivative models. We show that the model admits a rheological approximation, that is, an approximation by classical springs and dashpots. The model and rheological representation are compared to experimental data.     

Sustainable Disposal of Domestic Sanitary Waste

The study presented is an example of the assessment of the relative sustainability of either option for disposal of domestic sanitary waste, either via the toilet or via the solid waste route. This required an evaluation of the total (social, economic, environmental, and technical) benefit/cost of implementing and adopting the alternative routes and an assessment of public responsiveness to encouragement to change sanitary waste disposal practices. It illustrates how, even for an apparently straightforward either/or question, the assessment of relative sustainability is complex and the amount of data needed to quantify sustainability indicators is prodigious. The study also provides an appraisal of the effectiveness of public campaigns to reduce waterborne disposal. Important information regarding public attitude and behavior in relation to wastewater systems has been acquired and lessons for ways of encouraging behavioral change to more sustainable ways of living have been gleaned.     

NASA EOS Terra ASTER: Volcanic topographic mapping and capability

Up-to-date, accurate topographic data are a crucial resource for volcanic research and risk mitigation efforts, in particular, for modeling volcanic flow processes at a detailed spatial resolution. In this paper, we examine the utility of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument currently operating on the NASA Terra satellite, which provides near infrared (VNIR) stereo imaging from which topography can be derived. We wrote software to generate digital elevation models (DEMs) from the ASTER level 1A product, which employs an automated stereo matching technique to calculate the parallax offsets between the images acquired by the nadir- and aft-looking sensors. Comparison of ASTER DEMs with DEMs derived from other sources (digitized 1:50 K topographic maps and aerial interferometric radar) at Ruapehu volcano reveal an RMS error of about 10 m for the ASTER DEM, in the absence of significant atmospheric water vapor. A qualitative assessment of surface features showed that the ASTER DEM is superior to the interpolated 1:50 K map product but falls short of the detail provided by aerial interferometric radar, especially in terms of stream channel preservation. A second ASTER DEM was generated for Taranaki volcano, where previously only 1:50 K topographic map data were available. Although the 2000 Space Shuttle radar topography mission (SRTM) will largely remedy the previous global paucity of adequate topographic data at volcanoes, such as Taranaki, we anticipate the problem that at active volcanoes, the topography may change significantly following activity, rendering the SRTM data inaccurate. With the high temporal coverage of the dataset, ASTER not only provides a means to update significant (>10 m) topographic measurements at active volcanoes via a time-series of DEMs, but also provides a simultaneous means to map surface cover and localized land-use via the near infrared sensors. Thus we demonstrate the potential for up-to-date volcanic economic risk assessment using geographic information systems (GIS) analysis.     

High Intensity Ultrasound as an Abiotic Elicitor—Effects on Antioxidant Capacity and Overall Quality of Romaine Lettuce

The effect of ultrasound treatment at low acoustic power density (APD) on antioxidant capacity and overall quality of Romaine lettuce was evaluated. Whole leaf lettuce was treated with ultrasound (25 kHz) at APD of 26 W/L for 1–3 min and stored at room temperature for up to 150 h. Quality indices examined included color, texture, total phenolics, antioxidant capacity, and sensory properties. Phenylalanine ammonia-lyase (PAL) activity of lettuce from different treatments was monitored during storage. There were no differences in sample quality attributes between ultrasound treatment and control immediately after treatment. Lettuce treated with ultrasound exhibited an increase in PAL activity after storage for 60 h, resulting in production of phenolic compounds as secondary metabolites and enhancement of antioxidant capacity. Ultrasound-treated samples did not exhibit deterioration during storage, and under certain conditions, it delayed enzymatic browning and maintained better overall quality. A hypothetical model for the effect of low APD ultrasound as an abiotic elicitor on fresh produce was proposed based on the finding of present study and evidence from previous reports on response of cell cultures to ultrasond treatment.     

Children's perceptions of the outcomes of social strategies: Do the ends justify being mean?

Two studies were conducted to examine the strategy outcome perceptions of popular, average, neglected, and rejected 3rd- and 5th-graders. In Study 1, children (n?=?127) described the likely outcomes of 6 types of strategies (e.g., physical aggression, commands, compromise) in open-ended, hypothetical situation interviews. In Study 2 (n?=?339), a questionnaire was used to assess children's outcome expectations and their evaluations of selected strategies. Findings indicate that children's outcome expectations and strategy evaluations vary as a function of peer status, age, and gender. Results from both studies are discussed in terms of an hypothesized relation between children's strategy outcome perceptions and their behavior in the peer group. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The concept of physical metric in rate-independent generalized plasticity

A new internal variable formulation of rate-independent generalized plasticity is presented. The formulation relies crucially on the consideration of the physical (referential) metric as a primary internal variable and does not invoke any decomposition of the kinematical quantities into elastic and plastic parts. On the basis of a purely geometrical argument, namely the invariance of a set under the action of the flow of a vector field, the transition to classical plasticity is demonstrated. The covariant balance of energy is systematically employed for the derivation of the mechanical state equations. It is shown that unlike the case of finite elasticity, in finite plasticity the covariant balance of energy does not yield the Doyle?CEricksen formula, unless a further assumption is made. As an application, a material model is developed and is tested numerically for the solution of several problems of large-scale plastic flow.     

Relational and overt aggression in preschool.

This research was designed as an initial attempt to assess relational aggression in preschool-age children. Our goal was to develop reliable measures of relational aggression for young children and to use these instruments to address several important issues (e.g., the relation between this form of aggression and social–psychological adjustment). Results provide evidence that relationally aggressive behaviors appear in children's behavioral repertoires at relatively young ages, and that these behaviors can be reliably distinguished from overtly aggressive behaviors in preschool-age children. Further, findings indicate that preschool girls are significantly more relationally aggressive and less overtly aggressive than preschool boys. Finally, results show that relational aggression is significantly related to social–psychological maladjustment (e.g., peer rejection) for both boys and girls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of an optimised papaya pulp nectar using a combination of irradiation and mild heat

Papaya does not sufficiently maintain desired fresh fruit quality when shipped long distances due to an easily bruised soft skin and a short shelf life. This leads to both a large supply of pulp from unsightly fruit that is never shipped and low sales due to blemished fruit. Unfortunately, traditional preservation methods (pasteurisation) negatively alter papaya’s fresh flavour. Thus to effectively utilise available papaya pulp, processing requires an approach that enables retention of papaya’s natural flavours without excessive heat. Papaya fruit (Carica papaya L., var.’s Rainbow (yellow-fleshed) and SunUp (red-fleshed)) were pulped, diluted, and processed with mild heat (80 °C, 5 min), irradiation (5 kGy or 7.5 kGy) or combinations of both. Irradiation resulted in a significant reduction in ascorbic acid content. Mild heat treatment significantly reduced pectinesterase activity and microbiological viability. Irradiation followed by heat further enhanced destruction of Listeria innocua and Clostridium sporogenes and retained the flavour and a nutritional profile closest to untreated controls. The product was microbiologically safe with acceptable enzyme levels and would be shippable under refrigeration.     

Alternating Cationic-Hydrophobic Peptide/Peptoid Hybrids: Influence of Hydrophobicity on Antibacterial Activity and Cell Selectivity

The influence of hydrophobicity on antibacterial activity versus the effect on the viability of mammalian cells for peptide/peptoid hybrids was examined for oligomers based on the cationic Lys-like peptoid residue combined with each of 28 hydrophobic amino acids in an alternating sequence. Their relative hydrophobicity was correlated to activity against both Gram-negative and Gram-positive species, human red blood cells, and HepG2 cells. This identified hydrophobic side chains that confer potent antibacterial activity (e. g., MICs of 2–8 μg/mL against E. coli) and low toxicity toward mammalian cells (<10 % hemolysis at 400 μg/mL and IC₅₀>800 μg/mL for HepG2 viability). Most peptidomimetics retained activity against drug-resistant strains. These findings corroborate the hypothesis that for related peptidomimetics two hydrophobicity thresholds may be identified: i) it should exceed a certain level in order to confer antibacterial activity, and ii) there is an upper limit, beyond which cell selectivity is lost. It is envisioned that once identified for a given subclass of peptide-like antibacterials such thresholds can guide further optimisation.