Top PDF Fine-scale behavioural adjustments of prey on a continuum of risk

Fine-scale behavioural adjustments of prey on a continuum of risk

Fine-scale behavioural adjustments of prey on a continuum of risk

In tandem with this shift to faster swimming in front of predators, prey reduced distances between themselves and their nearest neighbours when predators were active. Group- ing more closely is a common evolutionary response to predation [59–62]. Indeed, research suggests that individuals within a group can reduce risk by moving towards neigh- bours and by positioning themselves closer to the centre of the group, ultimately resulting in the formation of denser aggregations [47,63]. This can explain why in many systems, we see the formation of more compact groups after exposure to a predator [39,64–67]. In the current study, we found the smallest neighbour distances occurred when prey were directly in front of an active predator, suggesting that prey were capable of gauging risk not based solely on predator presence, but based on the predator’s behavioural state and angular position. The fact that prey did not consistently form more cohesive groups in the presence of a predator implies that there may be costs associated with remaining cohesive. These costs, for example, could include increased cognitive demands associated with the coordination of this behaviour, or increased competition for resources. Ulti- mately, understanding how animal decision making circuits integrate multiple forms of information including the state and position of the predator, the position of neighbours and the costs and benefits of cohesion, will provide an intri- guing avenue for future research, particularly from a neurological perspective.
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Fine-scale behavioural adjustments of prey on a continuum of risk

Fine-scale behavioural adjustments of prey on a continuum of risk

In tandem with this shift to faster swimming in front of predators, prey reduced distances between themselves and their nearest neighbours when predators were active. Group- ing more closely is a common evolutionary response to predation [59–62]. Indeed, research suggests that individuals within a group can reduce risk by moving towards neigh- bours and by positioning themselves closer to the centre of the group, ultimately resulting in the formation of denser aggregations [47,63]. This can explain why in many systems, we see the formation of more compact groups after exposure to a predator [39,64–67]. In the current study, we found the smallest neighbour distances occurred when prey were directly in front of an active predator, suggesting that prey were capable of gauging risk not based solely on predator presence, but based on the predator’s behavioural state and angular position. The fact that prey did not consistently form more cohesive groups in the presence of a predator implies that there may be costs associated with remaining cohesive. These costs, for example, could include increased cognitive demands associated with the coordination of this behaviour, or increased competition for resources. Ulti- mately, understanding how animal decision making circuits integrate multiple forms of information including the state and position of the predator, the position of neighbours and the costs and benefits of cohesion, will provide an intri- guing avenue for future research, particularly from a neurological perspective.
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Fine-scale behavioural differences distinguish resource use by ecomorphs in a closed ecosystem.

Fine-scale behavioural differences distinguish resource use by ecomorphs in a closed ecosystem.

in prey abundance. It is possible this strategy was employed by the Pelagic morph charr in our study. However, despite synchrony with the annual fluctuations in resource availability, it is likely that resource competition is intensified in winter, resulting from depletion of resources and restriction of littoral habitat 55 . The relative contribution of littoral and pelagic production for whole ecosystem metabolism can be highly spatially and temporally variable within a lake and Arctic charr have evidently adapted to seasonal fluctuations in food availability and composition. Such generalist foraging by fish has been shown to be particularly evident in the high-latitudes where consumers must adapt to dramatic seasonal changes in prey availability, light and temperature 29,30 . Understanding the role of spatio-temporal aspects of differentiation in ecological niche use among model-organism population com- ponents, in this case of charr, could be strengthened with improved knowledge of the physiological processes by which they may occupy different niches. The physiological requirements and feeding behaviour of fish exhibit- ing dietary specialisation is highly dependent on individual morphology because this affects foraging efficiency, predation risk, competitive dominance and basic metabolic rate. As Littoral and Pelagic morphs exploit environ- ments with different feeding opportunities, temperature and light conditions, it might be expected that variation in aerobic metabolism and growth efficiencies in relation to water temperature would be observed, which to our knowledge has not been investigated.
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CARINA data synthesis project: pH data scale unification and cruise adjustments

CARINA data synthesis project: pH data scale unification and cruise adjustments

This is leg 1 of the experiment called SFB460 (M50 / 1), car- ried out on board R / V Meteor in the subpolar North At- lantic. It has 53 stations sampled with a 24 position rosette system. The analysis of pH was done using spectropho- tometric method with precision of ±0.002. Original data were reported on the Total pH scale at 21 ◦ C. The cruise has 7 crossovers. The inversion suggests a correction of −0.008 ± 0.005. Except for two crossovers, all residuals are very low and fit inside ±0.005 after the full solution of the inversion is applied. Very good fit also exists with two core cruises. Based on this evidence, an adjustment of −0.008 was applied to the pH data.
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Option-Implied Preferences Adjustments and Risk-Neutral Density Forecasts

Option-Implied Preferences Adjustments and Risk-Neutral Density Forecasts

function. This may not be surprising given the risk-neutrality embedded in these estimates. In other words, these papers suggest that the forecasting differences arise from the risk aversion of the representative investor. In fact, by imposing a stationary utility function (a stationary risk aversion parameter), Anagnou, Bedendo, Hodges and Tompkins (2003) and Bliss and Panigirtzoglou (2004) test whether either power or exponential utility functions are improved forecasters of future values of the underlying. In general, they are not able to reject the null that implied risk-adjusted densities are unbiased forecasts of future outcomes. However, Bliss and Panigirtzoglou obtain a disturbing result in the sense that the implicit risk aversion parameter they estimate increases as market risk declines. This suggests a misspecification of the utility functions imposed in their paper and, as in the asset pricing literature, it points out towards alternative utility functions with habit persistence and where the risk aversion parameter is not theoretically linked to the elasticity of intertemporal substitution.
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SATHELI. The potential of VHR remote sensing for fine-scale risk mapping of Fasciola hepatica. BEO day - Lier

SATHELI. The potential of VHR remote sensing for fine-scale risk mapping of Fasciola hepatica. BEO day - Lier

De Roeck, E., Van Coillie, F., Soenen, K., Charlier, J., Vercruysse, J., Hantson, W., Ducheyne, E., Hendrickx, G., De Wulf, R. (2014). Fine- scale mapping of vector habitats using very high resolution satellite imagery: a case-study on liver fluke, Geospatial Health (in press) Charlier, J., Soenen, K., Vercruysse, J., Van Coillie, F., De Roeck, E., De Wulf, R., Hantson, W., Ducheyne, E., Hendrickx, G., Longitudinal study on the temporal and micro-spatial distribution of Galba truncatula in four farms in Belgium as a base for small-scale risk mapping of Fasciola hepatica, Parasite and Vectors (in press)
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A Continuum Approach to Systemic Risk and Too-Big-to-Fail

A Continuum Approach to Systemic Risk and Too-Big-to-Fail

I contend that is important to recognize transactions that have the practical effect of nationalizing or otherwise providing the government with a substantial equity stake in a private business for what they are. In other words, they should be regarded as government interventions located on the far public end of the private-public risk continuum. I do not mean here to make any judgments about whether such transactions are good or bad under any particular circumstances of financial distress. I argue simply that we should treat functionally equivalent types of government intervention or assistance alike so as to provide similar access—as well as comparable substantive and procedural rights and protections—to all relevant parties, including general taxpayers. Different intervention categories along the private-public continuum can raise different sets of policy issues. With regard to nationalization in particular, the U.S. government has little past experience addressing the host of issues regarding the scope of the government’s corporate management role when it owns a substantial equity stake in an otherwise private business. One lesson from the recent economic crisis is that policy makers should anticipate the possibility of such government interventions. Policy makers should not pretend that the government cannot and should not use its regulatory and other authority in extreme cases to take an equity interest in an otherwise private firm. Instead, they should begin to address potential policy questions during a time of sober reflection rather than in ad hoc crisis mode.
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Adjustments of the pesticide risk index used in environmental policy in Flanders

Adjustments of the pesticide risk index used in environmental policy in Flanders

* davina.fevery@ugent.be Abstract Indicators are used to quantify the pressure of pesticides on the environment. Pesticide risk indicators typically require weighting environmental exposure by a no effect concentration. An indicator based on spread equivalents ( ΣSeq) is used in environmental policy in Flan- ders (Belgium). The pesticide risk for aquatic life is estimated by weighting active ingredient usage by the ratio of their maximum allowable concentration and their soil halflife. Accurate estimates of total pesticide usage in the region are essential in such calculations. Up to 2012, the environmental impact of pesticides was estimated on sales figures provided by the Federal Government. Since 2013, pesticide use is calculated based on results from the Farm Accountancy Data Network (FADN). The estimation of pesticide use was supple- mented with data for non-agricultural use based on sales figures of amateur use provided by industry and data obtained from public services. The Seq-indicator was modified to better reflect reality. This method was applied for the period 2009-2012 and showed differences between estimated use and sales figures of pesticides. The estimated use of pesticides based on accountancy data is more accurate compared to sales figures. This approach re- sulted in a better view on pesticide use and its respective environmental impact in Flanders.
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Conflict and cooperation in paranoia: a large-scale behavioural experiment

Conflict and cooperation in paranoia: a large-scale behavioural experiment

Statistical approach We used multi-model selection with model averaging (Burnham & Anderson, 2002 ; Grueber et al. 2011 ) to compare the explanatory power of different input vari- ables. Continuous input variables were standardised (Gelman, 2008 ) and binary input variables were centred, so estimates can be considered on the same scale. Under this approach, we first specify a global model, containing all fixed effects and interactions that were specified in the pre-registered predictions. All possible models deriving from this global model are compared, resulting in a top model set, which con- tains all the models that are within 2 AICc units of the ‘best’ model (that with the lowest AICc value). Parameter estimates are obtained by averaging across this top model set. This approach therefore incorpo- rates the uncertainty over the true parameter estimate when many models have similar levels of support. All estimates reported here are full model averages, which provide conservative estimates for terms that are not included in all the top models. All data and code are available at Raihani & Bell ( 2017b ) https:// figshare.com/s/c5bbc8330551b14bc91e .
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A Large Scale Behavioural Analysis of Bots and Humans on Twitter

A Large Scale Behavioural Analysis of Bots and Humans on Twitter

To answer the above questions, we build on our previous work [25] to perform a large-scale measurement and analysis campaign of Twitter (§3). We focus on bots in Twitter because it largely exposes public content, and past studies indicate a substantial presence of bots [11]. Addressing existing limitations of automated bot detection algorithms, we utilise a human annotation task to manually identify bots, providing us with a large ground-truth for statistical analysis. We offer a new and fundamental understanding of the characteristics of bots vs. humans, observing a number of clear differences (§4). For example, we find that humans generate far more novel content, while bots rely more on retweeting. We also observe less intuitive trends, such as the propensity of bots to tweet more URLs, and upload bulkier media (e.g. images). We also see divergent trends between different popularity groups (based on follower counts), with, for example, popular celebrities utilising bot-like tools to manage their fanbase. We then move on to explore the types of network traffic that bots may induce by sharing content and links (URLs) via Twitter. Specifically, this involves inspecting (i) the amount of data traffic bots generate on Twitter, and (ii) the nature of this traffic in terms of media type, i.e. URL, photo (JPG/JPEG), animated image (GIF), and video (MP4). We briefly touch upon on the possibilities of how this ever-increasing bot traffic might affect networked systems and their properties. Finally, we analyse the social interconnectedness of bots and humans to characterise how they influence the wider Twittersphere (§5). We observe that, although human contributions are considered more important via typical metrics (e.g. number of likes, retweets), bots still sustain significant influence over content production and propagation. Our experiments confirm that the removal of bots from Twitter could have serious ramifications for information dissemination and content production on the social network. As well as providing a powerful underpinning for future bot detection methods, our work makes contributions to the wider field of social content automation. Such understanding is critical for future studies of social media, which are often skewed by the presence of bots.
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Behavioural risk at outdoor music festivals

Behavioural risk at outdoor music festivals

Some venue owners and/or operators adopted a two-tier risk assessment approach. These were venues where one-off events are held either as a normal part of, or in addition to, their operations. The first tier is a general risk assessment which focuses on problems that are common to most circumstances (eg: poor design, crowd flows and aspects of emergency management/evacuation). The second tier risk assessment looks at problems that are specific to individual events. For example, problems associated with visitors’ behaviour tend to vary between visitor types and, therefore, have to be considered in the context of each event. The main benefit of this approach is that instead of carrying out a full scale risk assessment every time an event is to be held, all the assessors have to do is focus on things that are not covered in the general assessment or where its findings are not applicable.
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Risk-based audits in a behavioural model.

Risk-based audits in a behavioural model.

As noted in Section 1, there is evidence that older taxpayers are more compliant. A similar phenomenon has been observed in other areas. For example, Morin and Suarez (1983) investigated the household demand for risky assets for a large sample of Canadian households and found that risk aversion increases uniformly with age. Bakshi and Chen (1997), using the aggregate U.S. time series data, find that risk aversion increases as population ages. Wang and Hanna (1997) studied the effect of age on risk tolerance using the 1983-89 panel of the U.S. Survey of Consumer Finances. In this study risk tolerance is measured by the ratio of risky assets to total wealth, where total wealth is comprised of human capital and net worth. Contrary to the previous studies, they find that, controlling for other variables, risk tolerance increases with age. These findings are not necessarily inconsistent with the assumption of unchanging preferences. It is possible they can be explained by changes in wealth levels over the lifecycle; but, as wealth typically accumulates with age, positive effect of age in risk aversion would require the latter to be an increasing function of wealth which is generally counter to evidence. In fact, as pointed out by Riley and Chow (1992), various studies find that risk aversion increases, decreases or does not change with wealth depending on how wealth is defined. Alternative potential explanations include shortening of the time interval over which any bad outcomes could be corrected or limitations on borrowing to smooth consumption after adverse realizations.
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The Climate-Air Quality Scale Continuum and the Global Emission Inventory Activity

The Climate-Air Quality Scale Continuum and the Global Emission Inventory Activity

relationships may be derived between AOGCM variables and local variables reflecting physiographic features, land-sea distribution and land use. Continental to regional scale chemical transport air quality models are increasingly sophisticated, and now operate at spatial resolutions which range at the upper bound from the finer resolutions of regional climate models (approximately 50 to 100 km) down to 4 km resolution or less, such as CMAQ. The increased role of these chemical transport models is recognized in the Global Integration and Modeling (GIM) work, which, like GEIA, is a cross-cutting activity of IGAC, and seeks to improve coordination and inter-comparison of chemical transport models. 6 Data Needs
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Predicting large scale fine grain energy consumption

Predicting large scale fine grain energy consumption

a linear regression of the power used for heating on the difference between the internal temperature and the external temperature. Instead, the work in [22] presented a centralized engine exploiting exploratory data mining algorithms such as association rules and clustering to characterize energy consumption in buildings. Differently from the above research works [19,20,22], this paper proposes a distributed data mining engine exploiting data mining algorithms to predict fine grain energy consumption. The works cited prevously have a completely different target and analysis approach, and a substantially different architecture (the only similarity lies in the datawarehouse design). Specifically, the target of [19] and [22] is power consumption characterization and the target of [20] is the characterization of energy efficiency to define a building ranking. Whereas this current work aims at predicting energy consumption over a sliding time window. Furthermore, the methodology proposed in [19] and [20] exploits the Map-Reduce paradigm, while this work exploits the Apache Spark implementation.
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Recolonizing gray wolves increase parasite infection risk in their prey

Recolonizing gray wolves increase parasite infection risk in their prey

1 | INTRODUCTION Apex predators play a critical role in shaping food webs (Estes et al., 2011). When a predator is a definitive host of a parasite and disap- pears from its habitat, it may leave a gap in the food web. Potential consequences of such disappearances for parasite–host relation- ships are still poorly understood. Even for well- studied temperate ecosystems, where the gray wolf (Canis lupus) is an apex predator and ungulates are its main prey, little is known about the parasitological consequences of a transient wolf removal/extinction (East, Bassano, & Ytrehus, 2011). Transmission dynamics of trophically transmitted pathogens and parasites that are well adapted to a specific host might change. Parasites could either adapt to alternative hosts or disappear overtime (Farrell, Stephens, Berrang- Ford, Gittleman, & Davies, 2015), which we call the “host flexibility” hypothesis and the “fading out” hypothesis, respectively. Wolves are definitive hosts for a wide range of endoparasites (Craig & Craig, 2005), but little is known about their possible influence on parasite prevalence in their ungulate prey if these serve as intermediate hosts, as in the case of helminths or apicomplexa (Lesniak, Heckmann et al., 2017). In partic- ular, it is unclear whether infection risk increases when a definitive host returns after being absent from a specific area for some time, and how infection risk varies among different prey species. It is also unclear which factors control parasite etiopathology and whether these factors favor specialization of parasites for specific hosts. The process of the current wolf recolonization of Central Europe pro- vides an excellent opportunity to investigate parasite transmission dynamics in a predator–prey system as the same prey species can be examined in the presence and absence of the predator in the same habitat type.
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Fine-Scale Variability in Harbor Seal Foraging Behavior

Fine-Scale Variability in Harbor Seal Foraging Behavior

Conclusions The variation in dive behavior over time that we observed suggests fluctuations in the predominant prey consumed by harbor seals. These variations may be related to annual migrations and movements of available prey in the study area. We were able to identify differences between two relatively close haul-out sites, which may allude to larger behavioral differences, such as prey specialization or habitat exploitation by different haul-out site groups. Prey specialization, with forage fish specialists and salmon specialists, has already been documented for harbor seals in southern Puget Sound [28] and likely explains the variation in diet and foraging behavior observed for harbor seals in this study [20,50]. Bird Rocks and Padilla Bay showed similar variations in the use of different bout types; however, seals from Bird Rocks significantly changed the ratio of Type I to Type II bouts between seasons while seals from Padilla Bay did not. Bird Rocks seals dramatically increased the number of Type II bouts during the breeding season while Padilla Bay seals continued to use more Type I bouts. This change in behavior, which coincided with prey fluctuations in the region, suggests prey specialization between the two sites. Additionally, the increase in Type II bouts by males during the breeding season at both sites suggests that seals in both regions may maintain underwater breeding territories at or near foraging areas. These results provide a better understanding of the variability in harbor seal foraging behavior in the San Juan Islands
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Higher predation risk for insect prey at low latitudes and elevations

Higher predation risk for insect prey at low latitudes and elevations

compounded by mortality from other sources, such as microbes and weather (38). In order to measure the relative risk of predation across sites, we controlled for these other sources of mortality by monitoring attacks on model lepidopteran caterpillars of a standardized appearance (39). In doing so, we adhered to recently-established best practices for this technique (19). All participants were supplied with model caterpillars manufactured by the same team of people using odorless, non-toxic colored plasticine (Lewis NewplastTM in an equal mixture of two colors: green and light green). Model caterpillars resembled undefended, green geometrid larvae. This type of caterpillar was chosen as it represents one of the most abundant groups of Lepidoptera found throughout the world: Geometridae are among the largest families in the animal kingdom, with some 23,000 currently described species (40, 41), including many economically important species (42, 43). The caterpillars were manufactured with a clay gun in the typical size of late-instar geometrid caterpillars (2.5 x 30 mm) and molded into the characteristic
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Worth the Risk? The Behavioural Path to Well-Being

Worth the Risk? The Behavioural Path to Well-Being

Outside of the agricultural sphere, risk aversion has been found to be significantly associated with economic well-being (e.g. income and wealth). The argument here is that risk aversion affects investment behavior, with risk averse individuals being relatively more willing to forego higher expected returns, for returns with lower variability. Our analysis of farm operators is in line with this existing research, as we find that farmers who are more risk averse earn, all things being equal, less income from their farm business. In addition to being significantly related with objective indicators of success, our results also suggest that farmers who are relatively more risk averse are less likely to enjoy higher life satisfaction scores. One potential explanation is that in the same way that risk aversion inhibits people from engaging in certain behaviours that are net-income enhancing, but carry risks of failure, it may also constrain farmers (and indeed the general public at large) from activities that would on average improve their self-reported life satisfaction. Of course it is possible that bi-directional causality could be partly driving these results in that happiness itself could lead individuals to be less risk averse. Future longitudinal and/or work using instrumental variables would be useful to further unpick the direction of these relationships. There is also perhaps a need for further work to explore the extent to which farmers, as a group, are more or less risk averse than other groups, and also whether the apparent association between risk aversion and life satisfaction which we find in our sample is replicated among other groups in society.
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Origin of the Fine Scale Tortuosity in Sparks and Lightning Channels

Origin of the Fine Scale Tortuosity in Sparks and Lightning Channels

bursts and hence the length of the newly created leader segments as the background electric field 249. increases[r]

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Censored rainfall modelling for estimation of fine scale extremes

Censored rainfall modelling for estimation of fine scale extremes

Significant effort has been made since the late 1980s to improve the performance of mechanistic rainfall mod- els through structural developments, with substantial focus on the improved representation of fine-scale extremes (see Sect. 2 for a review). Despite this, little progress has been achieved. To test our hypothesis, a simple approach is pro- posed in which low observations for fine-scale data are cen- sored from the models in calibration. For a given temporal resolution, a censor amount is set. Rainfall below the cen- sor is set to zero and rainfall over the censor is reduced by the censor amount. This focusses model fitting on the heav- ier portion of the rainfall record at fine temporal scales, and reduces rainfall intensity at coarser scales. The aim is to in- vestigate whether existing mechanistic models can be used as simulators of fine-scale storm events by changing the data and not the model, thereby reducing the impact of low ob- servations and sampling error on fine-scale extreme rainfall estimation.
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