Extreme events and ecological forecasting

Almost all extreme events lasting less than several weeks that significantly impact ecosystems are weather related. This review examines the response of estuarine systems to intense short-term perturbations caused by major weather events such as hurricanes. Current knowledge concerning these effects is limited to relatively few studies where hurricanes and storms impacted estuaries with established environmental monitoring programs. Freshwater inputs associated with these storms were found to initially result in increased primary productivity. When hydrographic conditions are favorable, bacterial consumption of organic matter produced by the phytoplankton blooms and deposited during the initial runoff event can contribute to significant oxygen deficits during subsequent warmer periods. Salinity stress and habitat destruction associated with freshwater inputs, as well as anoxia, adversely affect benthic populations and fish. In contrast, mobile invertebrate species such as shrimp, which have a short life cycle and the ability to migrate during the runoff event, initially benefit from the increased primary productivity and decreased abundance of fish predators. Events studied so far indicate that estuaries rebound in one to three years following major short-term perturbations. However, repeated storm events without sufficient recovery time may cause a fundamental shift in ecosystem structure (Scavia et al. 2002). This is a scenario consistent with the predicted increase in hurricanes for the east coast of the United States. More work on the response of individual species to these stresses is needed so management of commercial resources can be adjusted to allow sufficient recovery time for affected populations

Experimental Studies on Habitat Preference and Thermoregulation of Bufo americanus, B. hemiophrys and B. cognatus

This paper reports on responses lo habitat and thermoregulotion exhibited by three species of toads, Bufo omericanus, B. hemiophrys and 8. cognalus, under artificial conditions. The response of the toads to sparse, medium, and dense vegetative cover was investigated by establishing artificial cover types in a sheet-metal enclosure. Each of the three species spent more time in the dense cover than i11 sparse or medium cover. A second experiment to determine if the toads would be attracted by odor to samples of mud, water, and vegetation from their respective ranges suggested that the toads moved randomly to the habitat samples. The role of temperature-regulating ability in habitat selection was evaluated by measuring deep body temperatures of the toads and surface temperature of the substrate under varying environmental conditions. The relations between body and surface temperature were significantly different for the three species as shown by analysis of covariance. 8. omericonus exhibited the most and B. cognotus the least thermoregulotion. The possible roles of these factors in causing the present distribution patterns of the three species ore considered

Cofinement, entropy, and single-particle dynamics of equilibrium hard-sphere mixtures

We use discontinuous molecular dynamics and grand-canonical transition-matrix Monte Carlo simulations to explore how confinement between parallel hard walls modifies the relationships between packing fraction, self-diffusivity, partial molar excess entropy, and total excess entropy for binary hard-sphere mixtures. To accomplish this, we introduce an efficient algorithm to calculate partial molar excess entropies from the transition-matrix Monte Carlo simulation data. We find that the species-dependent self-diffusivities of confined fluids are very similar to those of the bulk mixture if compared at the same, appropriately defined, packing fraction up to intermediate values, but then deviate negatively from the bulk behavior at higher packing fractions. On the other hand, the relationships between self-diffusivity and partial molar excess entropy (or total excess entropy) observed in the bulk fluid are preserved under confinement even at relatively high packing fractions and for different mixture compositions. This suggests that the partial molar excess entropy, calculable from classical density functional theories of inhomogeneous fluids, can be used to predict some of the nontrivial dynamical behaviors of fluid mixtures in confined environments.Comment: submitted to JC

Effects of environmental variables on invasive amphibian activity: using model selection on quantiles for counts

Many different factors influence animal activity. Often, the value of an environmental variable may influence significantly the upper or lower tails of the activity distribution. For describing relationships with heterogeneous boundaries, quantile regressions predict a quantile of the conditional distribution of the dependent variable. A quantile count model extends linear quantile regression methods to discrete response variables, and is useful if activity is quantified by trapping, where there may be many tied (equal) values in the activity distribution, over a small range of discrete values. Additionally, different environmental variables in combination may have synergistic or antagonistic effects on activity, so examining their effects together, in a modeling framework, is a useful approach. Thus, model selection on quantile counts can be used to determine the relative importance of different variables in determining activity, across the entire distribution of capture results. We conducted model selection on quantile count models to describe the factors affecting activity (numbers of captures) of cane toads (Rhinella marina) in response to several environmental variables (humidity, temperature, rainfall, wind speed, and moon luminosity) over eleven months of trapping. Environmental effects on activity are understudied in this pest animal. In the dry season, model selection on quantile count models suggested that rainfall positively affected activity, especially near the lower tails of the activity distribution. In the wet season, wind speed limited activity near the maximum of the distribution, while minimum activity increased with minimum temperature. This statistical methodology allowed us to explore, in depth, how environmental factors influenced activity across the entire distribution, and is applicable to any survey or trapping regime, in which environmental variables affect activity

The Effects of Caffeinated Gum and Caffeine Capsules on Running Sprint Performance

Use of anhydrous caffeine is an established and widely used ergogenic method. In sprinting events, optimum performance is highly dependent on the simultaneous peak functioning of a host of physiological systems. Therefore, caffeine supplementation protocols need to be perfectly timed in order to achieve culmination in sprint performance parameters within a narrow time window. Typically, caffeine capsules are ingested approximately 1 h before exercise however absorption rates may be highly variable. An alternative mode of ingestion is through caffeinated gum where caffeine is rapidly absorbed through the buccal mucosa. Our aim was to investigate the acute effects of two distinct modes of caffeine ingestion on sprint performance. Following ethics approval, eight trained male sprinters aged 20.2 (±0.8) took part in a screening and familiarisation session before they completed four trials (3x40 m sprints with 4 min recovery between runs) a week apart. A double-blind randomized crossover design was adopted where, during the trials, participants received: 1) Caffeine gum (CAFG, 6 mg.kg-1 of body weight), 2) CAFG placebo (CAFGP), 3) Caffeine capsules (CAFC, mg.kg-1 of body weight), 4) CAFC placebo (CAFCP). General and sport-specific warm-up commenced 15 minutes before sprint one. Capsules were given 45 minutes and chewing gums 15 minutes before sprint one. The gums were chewed for 5 minutes. Blood lactate and glucose concentration, heart rate, arousal and feeling levels were recorded at baseline and different time points during testing. Mean time to complete the three sprints were 5.00(±0.23), 5.03(±0.17), 5.10(±0.15), and 5.10(±0.14) seconds for the CAFG, CAFC, CAFGP and CAFCP conditions respectively. Participants ran significantly faster (p<0.05) during the caffeine compared to the placebo conditions. Additionally, sprint two in the CAFG (2.25±0.45 % faster than CAFGP) was significantly faster (p=0.022) than in the CAFC (1.40±0.32 % faster than CAFCP). Blood glucose and arousal levels were also significantly higher during the caffeine trials. Our data confirms that caffeine is an effective ergogenic strategy for sprinters. Furthermore, the greatest performance gains in sprint two suggests that caffeinated gum may be a more efficacious mode of ingestion than traditional methods of caffeine ingestion

Factors Governing Pasting Properties of Waxy Wheat Flours

Citation: Purna, S. K. G., Shi, Y. C., Guan, L., Wilson, J. D., & Graybosch, R. A. (2015). Factors Governing Pasting Properties of Waxy Wheat Flours. Cereal Chemistry, 92(5), 529-535. doi:10.1094/cchem-10-14-0209-rWaxy wheat (Triticum aestivum L.) contains endosperm starch lacking in amylose. To realize the full potential of waxy wheat, the pasting properties of hard waxy wheat flours as well as factors governing the pasting properties were investigated and compared with normal and partial waxy wheat flours. Starches isolated from six hard waxy wheat flours had similar pasting properties, yet their corresponding flours had very different pasting properties. The differences in pasting properties were narrowed after endogenous alpha-amylase activity in waxy wheat flours was inhibited by silver nitrate. Upon treatment with protease, the extent of protein digestibility influenced the viscosity profile in waxy wheat flours. Waxy wheat starch granules swelled extensively when heated in water and exhibited a high peak viscosity, but they fragmented at high temperatures, resulting in more rapid breakdown in viscosity. The extensively swelled and fragmented waxy wheat starch granules were more susceptible to a-amylase degradation than normal wheat starch. A combination of endogenous a-amylase activity and protein matrix contributed to a large variation in pasting properties of waxy wheat flours

Acoustic Investigation of Jet Mixing Noise in Dual Stream Nozzles

In an earlier study, a prediction model for jet noise in dual stream jets was proposed that is founded on velocity scaling laws in single stream jets and similarity features of the mean velocity and turbulent kinetic energy in dual stream flows. The model forms a composite spectrum from four component single-stream jets each believed to represent noise-generation from a distinct region in the actual flow. While the methodology worked effectively at conditions considered earlier, recent examination of acoustic data at some unconventional conditions indicate that further improvements are necessary in order to expand the range of applicability of the model. The present work demonstrates how these predictions compare with experimental data gathered by NASA and industry for the purpose of examining the aerodynamic and acoustic performance of such nozzles for a wide range of core and fan stream conditions. Of particular interest are jets with inverted velocity and temperature profiles and the appearance of a second spectral peak at small aft angles to the jet under such conditions. It is shown that a four-component spectrum succeeds in modeling the second peak when the aft angle refraction effects are properly incorporated into the model. A tradeoff of noise emission takes place between two turbulent regions identified as transition and fully mixed regions as the fan stream velocity exceeds that of the core stream. The effect of nozzle discharge coefficients will also be discussed

Broadcasting graphic war violence: the moral face of Channel 4

Drawing on empirical data from Channel 4 (C4) regarding the broadcasting of violent war imagery, and positioned within Goffman’s notion of the interaction ritual (1959, 1967), this article investigates how C4 negotiate potentially competing commercial, regulatory and moral requirements through processes of discretionary decision-making. Throughout, the article considers the extent to which these negotiations are presented through a series of ‘imaginings’ – of C4 and its audience – which serve to simultaneously guide and legitimate the decisions made. This manifestation of imaginings moves us beyond more blanket explanations of ‘branding’ and instead allows us to see the final programmes as the end product of a series of complex negotiations and interactions between C4 and those multiple external parties significant to the workings of their organization. The insights gleaned from this case study are important beyond the workings of C4 because they help elucidate how all institutions and organizations may view, organize and justify their practices (to both themselves and others) within the perceived constraints in which they operate