Salivary immunoglobulin A (sIgA) as a biomarker of immune suppression following the combat fitness assessment

SIgA is a potential biomarker for stress. The usual day-to-day and within day variation in sIgA amongst a group of healthy Army reservists was estimated and the acute response of sIgA to moderate intensity exercise (Combat Fitness Assessment) undertaken in both cool-dry and hot-humid conditions was determined. The results indicate that thermal and cardiovascular strain resulting from moderate intensity exercise in hot-humid conditions suppresses sIgA for at least 24 hours post-exercise. Salivary sIgA exhibits a wide biological variation which casts some doubt on its usefulness as a biomarker, however because sIgA has been shown to be sensitive to dietary restriction, alcohol consumption, loss of body mass, fatigue and negative emotions in previous studies and now heat-induced cardiovascular strain, further work is warranted to develop this biomarker.

Metformin counters the insulin-induced suppression of fatty acid oxidation and stimulation of triacylglycerol storage in rodent skeletal muscle

The present study examined the acute effects of metformin on fatty acid (FA) metabolism in oxidative soleus (SOL) and glycolytic epitrochlearis (EPT) rodent muscle. SOL and EPT were incubated for either 30 or 180 min in the absence or presence of 2 mM metformin and with or without insulin (10 mU/ml). Metformin did not alter basal FA metabolism but countered the effects of insulin on FA oxidation and incorporation into triacylglyerol (TAG). Specifically, metformin prevented the insulin-induced suppression of FA oxidation in SOL but did not alter FA incorporation into lipid pools. In contrast, in EPT metformin blunted the incorporation of FA into TAG when insulin was present but did not alter FA oxidation. In SOL, metformin resulted in a 50% increase in AMP-activated protein kinase α2 activity and prevented the insulin-induced increase in malonyl-CoA content. In both fiber types, basal and insulin-stimulated glucose oxidation were not significantly altered by metformin. All effects were similar regardless of whether they were measured after 30 or 180 min. Because increased muscle lipid storage and impaired FA oxidation have been associated with insulin resistance in this tissue, the ability of metformin to reverse these abnormalities in muscle FA metabolism may be a part of the mechanism by which metformin improves glucose clearance and insulin sensitivity. The present data also suggest that increased glucose clearance is not due to its enhanced subsequent oxidation. Additional studies are warranted to determine whether chronic metformin treatment has similar effects on muscle FA metabolism.

Suppression of necking in incremental sheet forming

Incremental sheet forming enables sheet metal to deform above a conventional strain-based forming limit. The mechanics reason has not been clearly explained yet. In this work, the stress-based forming limit was utilized for through-thickness necking analysis to explain this uncovered question. Stress-based forming limit which has path-independency shows that the stress states in top, middle and bottom surfaces did not exceed the forming limit curve at the same time and each layer has different stress state in terms of their deformation history to suppress necking. It has been found that it is important to consider the gradient stress profile following the deformation history for the proper forming limit analysis of incremental sheet forming. © 2014 Elsevier Ltd. All rights reserved.

Reduced mu suppression and altered motor resonance in euthymic bipolar disorder: evidence for a dysfunctional mirror system?

Social cognitive difficulties are common in the acute phase of bipolar disorder and, to a lesser extent, during the euthymic stage, and imaging studies of social cognition in euthymic bipolar disorder have implicated mirror system brain regions. This study aimed to use a novel multimodal approach (i.e., including both transcranial magnetic stimulation (TMS) and electroencephalogram (EEG)) to investigate mirror systems in bipolar disorder. Fifteen individuals with euthymic bipolar disorder and 16 healthy controls participated in this study. Single-pulse TMS was applied to the optimal site in the primary motor cortex (M1), which stimulates the muscle of interest during the observation of hand movements (goal-directed or interacting) designed to elicit mirror system activity. Single EEG electrodes (C3, CZ, C4) recorded mu rhythm modulation concurrently. Results revealed that the patient group showed significantly less mu suppression compared to healthy controls. Surprisingly, motor resonance was not significantly different overall between groups; however, bipolar disorder participants showed a pattern of reduced reactivity on some conditions. Although preliminary, this study indicates a potential mirror system deficit in euthymic bipolar disorder, which may contribute to the pathophysiology of the disorder.

Multiple days of heat exposure on firefighters' work performance and physiology

This study assessed the accumulated effect of ambient heat on the performance of, and physiological and perceptual responses to, intermittent, simulated wildfire fighting tasks over three consecutive days. Firefighters (n = 36) were matched and allocated to either the CON (19°C) or HOT (33°C) condition. They performed three days of intermittent, self-paced simulated firefighting work, interspersed with physiological testing. Task repetitions were counted (and converted to distance or area) to determine work performance. Participants were asked to rate their perceived exertion and thermal sensation after each task. Heart rate, core temperature (Tc), and skin temperature (Tsk) were recorded continuously throughout the simulation. Fluids were consumed ad libitum. Urine volume was measured throughout, and urine specific gravity (USG) analysed, to estimate hydration. All food and fluid consumption was recorded. There was no difference in work output between experimental conditions. However, significant variation in performance responses between individuals was observed. All measures of thermal stress were elevated in the HOT, with core and skin temperature reaching, on average, 0.24 ± 0.08°C and 2.81 ± 0.20°C higher than the CON group. Participants' doubled their fluid intake in the HOT condition, and this was reflected in the USG scores, where the HOT participants reported significantly lower values. Heart rate was comparable between conditions at nearly all time points, however the peak heart rate reached each circuit was 7 ± 3% higher in the CON trial. Likewise, RPE was slightly elevated in the CON trial for the majority of tasks. Participants' work output was comparable between the CON and HOT conditions, however the performance change over time varied significantly between individuals. It is likely that the increased fluid replacement in the heat, in concert with frequent rest breaks and task rotation, assisted with the regulation of physiological responses (e.g., heart rate, core temperature).

The effects of topographic variation and the fire regime on coarse woody debris: insights from a large wildfire

Coarse woody debris (CWD) is a common structural component of terrestrial ecosystems, and provides important habitat for biota. Fires modify the distribution of CWD, both spatially and temporally. Changes in fire regimes, such as those arising from prescribed burning and changing climatic conditions, make it critical to understand the response of this resource to fire. We created a conceptual model of the effects of fire on logs and dead trees in topographically diverse forests in which trees often survive severe fire. We then surveyed paired sites, in a damp gully and adjacent drier slope, ~3.5. years after a large wildfire in south-eastern Australia. Sites were stratified by fire severity (unburnt, understorey burnt and severely burnt), and fire history (burnt ≤3. years or ≥20. years prior to the wildfire). Both components of the fire regime influenced CWD availability in gullies. Severe wildfire and fire history ≤3. years reduced the volume of small logs (10-30. cm diameter) in gullies, while severe wildfire increased the number of large dead trees in gullies. CWD on slopes was not affected by fire severity or history at ~3.5. years post-fire. Log volumes on slopes may recover more quickly after wildfire through rapid collapse of branches and trees. Gullies generally supported more logs than slopes, but longer inter-fire intervals in gullies may allow fuel loads to accumulate and lead to comparatively larger fire impacts. Given that fire severity and fire interval are predicted to change in many fire-prone ecosystems in coming decades, this study highlights the importance of understanding the interacting effects of multiple components of the fire regime with landscape structure. In particular, variation in fire interval and fire severity in relation to topographic position will influence the pattern of accumulation of coarse woody debris across the landscape, and therefore the structure and quality of habitats for biota.

Religious ambivalence: suppression of pro-social attitudes toward asylum seekers by right-wing authoritarianism

A survey of 168 White Australian community members examined whether ambivalence toward certain social groups by some religious individuals constituted a suppression effect in which authoritarian motivated prejudice suppressed more pro-social attitudes toward asylum seekers. Using mediation analysis, it was found that Christian religious identity was not significantly associated with prejudice at a bivariate level. However, when Right-Wing Authoritarianism (RWA) was taken into account, Christians (compared with non-Christians) were less likely to hold negative attitudes toward asylum seekers in Australia. Inclusion of acculturation ideologies (assimilation, multiculturalism, and color-blindness) in the models indicated that the suppression effect was specific to RWA rather than due to other intergroup attitudes. However, findings suggest that multiculturalism may be one proximal indicator of Christian pro-sociality.

Effects of the fire regime on mammal occurrence after wildfire: site effects vs landscape context in fire-prone forests

Wildfires have major impacts on ecosystems globally. Fire regimes (including fire frequency, intensity, season and type of fire) influence the status of species by altering habitat suitability at the site scale, and by creating heterogeneity at the landscape scale. The relative effects of site and landscape-scale fire attributes on animal species are rarely examined together. Such knowledge is important, given that fire regimes are sensitive to changing land management practices; and that fires are predicted to become larger and more frequent in some regions as a result of climate change. Here, we tested the relative influence of elements of the fire regime (fire severity, fire history) at the site-scale, and the landscape context (extent of surrounding unburnt forest, fire heterogeneity) on the occurrence of native terrestrial mammals after severe wildfire in south-eastern Australia. We conducted surveys by using automatically triggered, infrared cameras at 80 sites in fire-prone eucalypt forests, 2-3. years post-wildfire. Thirteen native mammal species were recorded, eight of which were detected with sufficient frequency for analysis. Most species were widespread (35-90% of sites) and recorded in all fire severity classes. Fire effects at the site-level were more influential than landscape context effects arising from heterogeneity in the fire regime (e.g. extent of surrounding unburnt forest). Fire severity was the most influential of the fire-regime elements investigated, but it affected different species in different ways. This study highlights three main points relevant to conservation of terrestrial mammals after wildfire. First, spatial variation in fire severity associated with wildfire (ranging from unburned to severely burned stands) is an important contributor to the post-fire status of species. Second, post-fire environmental conditions are significant: here, rapid regeneration of vegetation following drought-breaking rains greatly influenced the suitability of post-fire habitats. Third, it is valuable to consider the effects of the fire regime at multiple scales, including both the site (forest stand) and its landscape context. Insights from short-term surveys, such as this, will be enhanced by complementary longitudinal studies, especially where they encompass environmental variation through the post-fire succession.

Successional specialization in a reptile community cautions against widespread planned burning and complete fire suppression

Summary: Conservation of biodiversity in fire-prone regions depends on understanding responses to fire in animal communities and the mechanisms governing these responses. We collated data from an Australian semi-arid woodland reptile community (4796 individuals captured over 6 years) to: (i) determine the ability of commonly used shorter-term (2 years) surveys to detect reptile responses to time since fire (TSF) and (ii) investigate whether ecological traits of species reliably predicted their responses to fire. Of 16 reptile species analysed, four had responses to TSF consistent with shorter-term surveys and three showed no response to TSF. Nine species had responses to TSF not detected in previous studies using smaller but substantial subsets of the same data. Among the 13 affected species, times of peak abundance ranged from 1 to 50 years after fire. Nocturnal, burrowing species tended to be early successional and leaf-litter dwellers to be late successional, but these were only weak trends. Synthesis and applications. We found only limited support for a generalizable, trait-based model of succession in reptiles. However, our study revealed that the majority of common reptile species in our study region specialize on a post-fire successional stage and may therefore become threatened if homogeneous fire regimes predominate. Our study highlights the importance of interpreting results from time- or sample-limited fire studies of reptiles with the knowledge that many ecological responses may not have been detected. In such cases, an adaptive or precautionary approach to fire management may be necessary. We found only limited support for a generalizable, trait-based model of succession in reptiles. However, our study revealed that the majority of common reptile species in our study region specialize on a post-fire successional stage and may therefore become threatened if homogeneous fire regimes predominate. Our study highlights the importance of interpreting results from time- or sample-limited fire studies of reptiles with the knowledge that many ecological responses may not have been detected. In such cases, an adaptive or precautionary approach to fire management may be necessary.

Suppression of interference in continuous wave Doppler radar based respiratory measurements

Microwave Doppler radar has received considerable attention as a non-contact form of measuring human respiration; in particular for long term monitoring. One of the main challenges in converting this into a viable application is to suppress or separate the artefacts and other interfering signals from the desired respiration signal using a less complex and practically feasible design for regular and potentially real time use. Existing systems either require complex experimental setups or multiple Doppler radar modules to achieve this. In this paper, we propose an approach based on EMD-ICA and approximate entropy ideas to systematically separate received Doppler shifted signal into distinct components and reconstruct the desired respiration pattern pertaining to respective physiological activity. Indeed this allows suppression of the undesirable artefacts and interference from other competing signals. Practical experiments confirmed comparable performance of the proposed method to the measurements obtained through chest straps which are widely used clinically for monitoring respiration.

Response of a shrubland mammal and reptile community to a history of landscape-scale wildfire

Fire plays a strong role in structuring fauna communities and the habitat available to them in fire-prone regions. Human-mediated increases in fire frequency and intensity threaten many animal species and understanding how these species respond to fire history and its associated effect on vegetation is essential to effective biodiversity management. We used a shrubland mammal and reptile community in semiarid south-western Australia as a model to investigate interactions between fire history, habitat structure and fauna habitat use. Of the 15 species analysed, five were most abundant in recently burnt habitat (8–13 years since last fire), four were most abundant in long unburnt areas (25–50 years) and six showed no response to fire history. Fauna responses to fire history were divergent both within and across taxonomic groups. Fire management that homogenises large areas of habitat through either fire exclusion or frequent burning may threaten species due to these diverse requirements, so careful management of fire may be needed to maximise habitat suitability across the landscape. When establishing fire management plans, we recommend that land managers exercise caution in adopting species-specific information from different locations and broad vegetation types. Information on animal responses to fire is best gained through experimental and adaptive management approaches at the local level.

Rapid recovery of an urban remnant reptile community following summer wildfire

Reptiles in urban remnants are threatened with extinction by increased fire frequency, habitat fragmentation caused by urban development, and competition and predation from exotic species. Understanding how urban reptiles respond to and recover from such disturbances is key to their conservation. We monitored the recovery of an urban reptile community for five years following a summer wildfire at Kings Park in Perth, Western Australia, using pitfall trapping at five burnt and five unburnt sites. The reptile community recovered rapidly following the fire. Unburnt sites initially had higher species richness and total abundance, but burnt sites rapidly converged, recording a similar total abundance to unburnt areas within two years, and a similar richness within three years. The leaf-litter inhabiting skink Hemiergis quadrilineata was strongly associated with longer unburnt sites and may be responding to the loss of leaf litter following the fire. Six rarely-captured species were also strongly associated with unburnt areas and were rarely or never recorded at burnt sites, whereas two other rarely-captured species were associated with burnt sites. We also found that one lizard species, Ctenotus fallens, had a smaller average body length in burnt sites compared to unburnt sites for four out of the five years of monitoring. Our study indicates that fire management that homogenises large areas of habitat through frequent burning may threaten some species due to their preference for longer unburnt habitat. Careful management of fire may be needed to maximise habitat suitability within the urban landscape.