Behavioral Responses of a Generalist Mammalian Folivore to the Physiological Constraints of a Chemically Defended Diet

Mammalian herbivores, particularly browsers and folivores, encounter and consume a range of plant chemical defenses [plant secondary metabolites (PSMs)] on a regular basis. The physiological regulation of PSM ingestion and the resulting behavioral responses of mammalian herbivores directly affect their feeding decisions and the subsequent foraging strategies that they adopt. Generalist mammalian herbivores are hypothesized to consume a generalized diet because of physiological limitations of their detoxification systems. The consumption of a generalized diet is proposed to enable toxin (PSM) dilution through the use of multiple detoxification pathways. We tested the predictions of the detoxification–limitation hypothesis by offering two chemically different plant species, Eucalyptus regnans and E. globulus, to a generalist mammalian folivore, the common brushtail possum (Trichosurus vulpecula), as single- and mixed-species diets. By feeding more efficiently, brushtail possums benefited more, through increased intake, on the mixed-species diet than on either of the single-species diets. We argue that frequently switching between chemically diverse foliage reduces the physiological constraints imposed by a PSM-rich diet and enables more efficient feeding. The behavioral responses of brushtail possums were consistent with the proposed physiological constraints of a chemically defended diet, offering support for predictions of the detoxification–limitation hypothesis. We suggest that feeding behavior of herbivores may be a useful indicator of the physiological constraints imposed by a chemically defended diet.     

Degradation analysis and modeling of reinforced catalyst coated membranes operated under OCV conditions

This paper studies the degradation of Gore™ PRIMEA^® series 5510 catalyst coated membranes with an ePTFE reinforcement layer under open circuit voltage conditions at 90 °C, 75% RH, and no backpressure. Scanning electron microscopy (SEM) imaging of cross-sections revealed extensive cathode-side ionomer degradation and the presence of a platinum band. Cumulative fluoride release measurements show more fluoride exiting with the cathode effluent. Furthermore, both anode and cathode cumulative fluoride release plateau after long degradation times. Open circuit voltage was also monitored and the degradation rate was found to decrease after a long duration. It is proposed that all fluoride species are generated from the cathode-side ionomer degradation process and that the fluoride then diffuses to the anode and cathode channels. Further, once the cathode-side ionomer is consumed the degradation reaction slows as the “degradation front” passes through the inert reinforcement layer. This process was modeled using a semi-empirical transient model and compared to experimental results.     

Shifts in the Gas-Particle Partitioning of Ambient Organics with Transport into the Indoor Environment

Predicting indoor exposures to ambient organic aerosol (OA) is complicated by shifts in the gas-particle partitioning of ambient organics with outdoor-to-indoor transport. This analysis aims to quantify the effect of changes in temperature and OA loading on the gas-particle partitioning of ambient organics transported indoors and explores whether accounting for shifts in partitioning closes the gap between measured indoor ambient OA concentrations and indoor concentrations calculated in a previous analysis using a model that accounts for only physical losses. Changes in the gas-particle partitioning of ambient organics with outdoor-to-indoor transport were calculated for 167 homes using measured temperatures and OA concentrations and published OA volatility distributions. Initially, it was assumed that ambient OA could be represented with a single volatility distribution. We then repeated the analysis treating ambient OA as the sum of distinct components, each with a distinct volatility distribution, derived from factor analysis of aerosol mass spectra (e.g., hydrocarbon-like OA [HOA], oxygenated OA [OOA]). We also evaluated the sensitivity of our calculations to uncertainty in the thermodynamic properties of ambient OA by varying the enthalpy of vaporization. Partitioning shifts were sensitive to enthalpy-of-vaporization assumptions and resulted in changes in indoor ambient OA concentrations of 13–27%. Our calculations indicate that phase changes are important determinants of residential exposure to ambient OA and are of sufficient magnitude to close the gap between measured and modeled indoor concentrations of ambient OA.

Copyright 2014 American Association for Aerosol Research     

Psychological adjustment and coping among construction project managers

Construction project managers work under conditions of uncertainty and high risk, and this can contribute to an excessive level of work‐related stress being experienced. To date, there has been limited research that has examined how project managers cope with work‐related stress. This paper investigates whether coping and affect (both negative and positive) influence adjustment (anxiety, depression and stress) among project managers. A sample of 100 male project managers from Australian contracting organizations completed a questionnaire that measured coping strategies, affect state and potential stressors. Hierarchical regression analyses demonstrated that specific work‐related characteristics such as work experience, project size, age and level of education influenced the psychological adjustment of the project managers sampled. Further, those who engaged in a more problem‐focused style of coping, such as active coping were found to be better adjusted than those who engaged in more emotion‐focused styles of coping such as cognitive avoidance coping, social coping, accepting responsibility and self‐controlling coping. In addition, it was revealed that increased adjustment of project managers was associated with positive affect. It is concluded that the psychological adjustment of project managers is influenced by specific work‐related characteristics, the types of coping strategies they use and their affect state.     

Including the influence of groundwater exchanges in a lumped rainfall-runoff model

The growing realisation that groundwater and surface water systems are components of connected hydrologic system has in recent years sparked the development of integrated surface–ground water models. In this paper, a version of the IHACRES rainfall-runoff model is presented, in which the CMD module for calculating effective rainfall is coupled to a streamflow-groundwater module, and applied to the Coxs Creek catchment, a variably gaining-losing stream system in Australia. The aim is to determine the capacity for the coupled model to capture the switching off–on behaviour evident in the observed flow record. Model performance can be improved in terms of event prediction, volume of baseflow and the percentile of flow cessation, through manipulation of CMD parameters, however, improvements in some performance criteria come at the expense of performance in others. An analysis of the input rainfall time-series, generated using a standard weighted Thiessen polygon approach, reveals mismatches between observed streamflow events and the occurrence of rainfall, which impose major limits on model performance. The challenge is to develop a simple lumped rainfall-runoff model that has the potential to improve system understanding and allow for meaningful exploration of alternate climate, groundwater extraction and land use change scenarios, given a situation of data poor catchments in many parts of Australia.     

Multimodal Events and Moving Locations: Eye Movements of Adults and 6-Month-Olds Reveal Dynamic Spatial Indexing.

The ability to keep track of locations in a dynamic, multimodal environment is crucial for successful interactions with other people and objects. The authors investigated the existence and flexibility of spatial indexing in adults and 6-month-old infants by adapting an eye-tracking paradigm from D. C. Richardson and M. J. Spivey (2000). Multimodal events were presented in specific locations, and eye movements were measured when the auditory portion of the stimulus was presented without its visual counterpart. Experiment 1 showed that adults spatially index auditory information even when the original associated locations move. Experiments 2 and 3 showed that infants are capable of both binding multimodal events to locations and tracking those locations when they move. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Attaining personal goals: Self-concordance plus implementation intentions equals success.

The present article includes separate meta-analyses showing that self-concordance and implementation intentions are significantly positively associated with goal progress. Study I confirmed the positive relations of both self-concordance and implementation intentions to weekend goal progress. Study 2 confirmed the positive relation of self-concordance with monthly progress on New Year's resolutions but failed to find a direct benefit for implementation intentions. Both studies, however, obtained a significant interaction effect indicating that goal self-concordance and implementation intentions combined synergistically to facilitate goal progress. The article also reports a meta-analysis and results from the 2 studies that demonstrated that goal progress was associated with improved affect over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)