Testing heterogeneous anchoring and shift effect in double-bounded models: The case of recreational fishing in Tasmania

This paper explores the extent and nature of anchoring and shift effects in a double-bounded contingent valuation of recreational fishing in Tasmania’s inshore saltwater fishery. In particular we model the situation where respondents, when answering the second valuation question, evaluate the bid amount partly with reference to the size of the first bid amount. The estimates of the coefficients and mean WTP for a day of fishing are compared across different contingent valuation models, including a single-bounded model, a conventional double-bounded model and models that control anchoring and exogenous shift effects in both homogeneous and heterogeneous forms. Overall we find consistent evidence of anchoring, but mixed evidence of a shift effect. Results show that both males and females anchor in the same way, but that respondents who have a mainstream view of what recreational fishing represents anchor more strongly than those whose view of fishing is not mainstream. The estimated mean WTP for a day’s recreational fishing is consistently higher in all models which account for bias in responses than in either the single-bounded or double-bounded models. We indicate the possibility that anchoring behaviour may be more complex than is captured in our models and suggest that this needs to be addressed if the results of contingent valuations are to reliably inform resource allocation decisions and recreational fishing management.Contingent valuation, anchoring bias, shift effect, heterogeneity, recreational fishing, Environmental Economics and Policy, C35, Q26,

Testing heterogeneous anchoring and shift effect in double-bounded models: The case of recreational fishing in Tasmania

This paper explores the extent and nature of anchoring and shift effects in a double-bounded contingent valuation of recreational fishing in Tasmania’s inshore saltwater fishery. In particular we model the situation where respondents, when answering the second valuation question, evaluate the bid amount partly with reference to the size of the first bid amount. The estimates of the coefficients and mean WTP for a day of fishing are compared across different contingent valuation models, including a single-bounded model, a conventional double-bounded model and models that control anchoring and exogenous shift effects in both homogeneous and heterogeneous forms. Overall we find consistent evidence of anchoring, but mixed evidence of a shift effect. Results show that both males and females anchor in the same way, but that respondents who have a mainstream view of what recreational fishing represents anchor more strongly than those whose view of fishing is not mainstream. The estimated mean WTP for a day’s recreational fishing is consistently higher in all models which account for bias in responses than in either the single-bounded or double-bounded models. We indicate the possibility that anchoring behaviour may be more complex than is captured in our models and suggest that this needs to be addressed if the results of contingent valuations are to reliably inform resource allocation decisions and recreational fishing management.Contingent valuation, anchoring bias, shift effect, heterogeneity, recreational fishing, Environmental Economics and Policy, C35, Q26,

Structural response monitoring of New Zealand bridges

In 2010, New Zealand introduced High Productivity Motor Vehicles onto the road network. To date, the movement of these heavier vehicles has been limited by the capacity of infrastructure, particularly bridges on the State Highway and local road networks. To limit the extent of costly bridge strengthening and replacement, the New Zealand Transport Agency is currently undertaking Structural Response Monitoring of three key bridges in the South Island. The Structural Response Monitoring systems employed to date include a range of conventional bridge monitoring and testing techniques, such as visual inspections, material testing, and survey levelling; as well as more advanced monitoring systems using accelerometers, displacement transducers, vehicle weigh-in-motion testing, advanced bridge model calibration, and concrete condition assessment. Whilst the monitoring is still its initial stages, significant conclusions around the structural performance of the bridges have already been made. These include the low likelihood of first degree resonance of the beams, calculation of a bridge specific impact factor, information on the continuity of the joints and interactions of the split piers. To minimise the cost of response monitoring, a five step methodology was developed. This included preliminary diagnostics, detailed bridge analysis and model calibration, assessment of critical failure mechanisms and focussed response monitoring on key regions under high stress. This paper outlines the findings of this testing and provides a cost effective solution for the monitoring of bridge structures

Optimal Design Of English Auctions With Discrete Bid Levels

This paper considers a form of ascending price English auction widely used in both live and online auctions. This discrete bid auction requires that the bidders submit bids at predetermined discrete bid levels, and thus, there exists a minimal increment by which the bid price may be raised. In contrast, the academic literature of optimal auction design deals almost solely with continuous bid auctions. As a result, there is little practical guidance as to how an auctioneer, seeking to maximize its revenue, should determine the number and value of these discrete bid levels, and it is this omission that is addressed here. To this end, a model of a discrete bid auction from the literature is considered, and an expression for the expected revenue of this auction is derived. This expression is used to determine both numerical and analytical solutions for the optimal bid levels, and uniform and exponential bidder’s valuation distributions are compared. Finally, the limiting case where the number of discrete bid levels is large is considered. An analytical expression for the distribution of the optimal discrete bid levels is derived, and an intuitive understanding of how this distribution maximizes the revenue of the auction is developed

Evaluation and management implications of uncertainty in a multispecies size-structured model of population and community responses to fishing

1. Implementation of an ecosystem approach to fisheries requires advice on trade-offs among fished species and between fisheries yields and biodiversity or food web properties. However, the lack of explicit representation, analysis and consideration of uncertainty in most multispecies models has limited their application in analyses that could support management advice. 2. We assessed the consequences of parameter uncertainty by developing 78 125 multispecies size-structured fish community models, with all combinations of parameters drawn from ranges that spanned parameter values estimated from data and literature. This unfiltered ensemble was reduced to 188 plausible models, the filtered ensemble (FE), by screening outputs against fish abundance data and ecological principles such as requiring species' persistence. 3. Effects of parameter uncertainty on estimates of single-species management reference points for fishing mortality (FMSY, fishing mortality rate providing MSY, the maximum sustainable yield) and biomass (BMSY, biomass at MSY) were evaluated by calculating probability distributions of estimated reference points with the FE. There was a 50% probability that multispecies FMSY could be estimated to within ±25% of its actual value, and a 50% probability that BMSY could be estimated to within ±40% of its actual value. 4. Signal-to-noise ratio was assessed for four community indicators when mortality rates were reduced from current rates to FMSY. The slope of the community size spectrum showed the greatest signal-to-noise ratio, indicating that it would be the most responsive indicator to the change in fishing mortality F. Further, the power of an ongoing international monitoring survey to detect predicted responses of size spectrum slope was higher than for other size-based metrics. 5. Synthesis and applications: Application of the ensemble model approach allows explicit representation of parameter uncertainty and supports advice and management by (i) providing uncertainty intervals for management reference points, (ii) estimating working values of reference points that achieve a defined reduction in risk of not breaching the true reference point, (iii) estimating the responsiveness of population, community, food web and biodiversity indicators to changes in F, (iv) assessing the performance of indicators and monitoring programmes and (v) identifying priorities for data collection and changes to model structure to reduce uncertainty

Prototype Vent Gas Heat Exchanger for Exploration EVA - Performance and Manufacturing Characteristics

NASA is developing new portable life support system (PLSS) technologies, which it is demonstrating in an unmanned ground based prototype unit called PLSS 2.0. One set of technologies within the PLSS provides suitable ventilation to an astronaut while on an EVA. A new component within the ventilation gas loop is a liquid-to-gas heat exchanger to transfer excess heat from the gas to the thermal control system's liquid coolant loop. A unique bench top prototype heat exchanger was built and tested for use in PLSS 2.0. The heat exchanger was designed as a counter-flow, compact plate fin type using stainless steel. Its design was based on previous compact heat exchangers manufactured by United Technologies Aerospace Systems, but was half the size of any previous heat exchanger model and one third the size of previous liquid-to-gas heat exchangers. The prototype heat exchanger was less than 40 cubic inches and weighed 2.6 lb. The water side and gas side pressure drops were 0.8 psid and 0.5 inches of water, respectively. Performance of the heat exchanger at the nominal pressure of 4.1 psia was measured at 94%, while a gas inlet pressure of 25 psia resulted in an effectiveness of 84%. These results compared well with the model, which was scaled for the small size. Modeling of certain phenomena that affect performance, such as flow distribution in the headers was particularly difficult due to the small size of the heat exchanger. Data from the tests has confirmed the correction factors that were used in these parts of the model

Effects of Stage 0 Stream Restoration on Aquatic Macroinvertebrate Production

Contemporary stream restoration efforts increasingly prioritize restoring natural stream processes to regain lost ecosystem functions. Stage 0 stream restoration resets disturbed, channelized streams to a theoretical pre-disturbance state (“stage zero”). It is assumed that this valley-scale restoration/disturbance will restore natural abiotic and biotic processes, leading to greater primary and secondary biological productivity, maximizing potential ecosystem services such as the abundance of desirable fish species. As stage 0 restoration projects have been implemented in Oregon and across North America, post-restoration studies have not fully assessed this assumption. In this study, I seasonally sampled aquatic macroinvertebrate communities and fish diets on the South Fork McKenzie River, OR in a reach that underwent stage 0 restoration in 2018, as well as two upstream, unrestored control reaches. I estimated total annual secondary macroinvertebrate production on the benthos and submerged wood surfaces, and constructed food webs from the dominant taxa found in fish diets. Contrary to expectations, annual production estimates were ~5-times lower on a per-meter-squared basis in the restored reach than in upstream unrestored reaches. However, because there was ~4.5-times greater wetted area available in the restored reach, overall macroinvertebrate production per-unit of valley length was 1.5-times higher than in unrestored reaches. Fish diet assemblages were also more complex in the treatment reach than in the control reaches. Additionally, a greater diversity of macroinvertebrate community assemblages was observed in the restored reach, suggesting that stage 0 restoration may produce a heterogeneous mosaic of fine-scale habitat patches and associated metapopulations. These findings suggest that stage 0 restoration may increase overall macroinvertebrate productivity, as well as creating a more diverse assembly of prey items, resulting in more consistent prey availability and greater overall habitat and foraging opportunities for fishes

Implications of the prevalence and magnitude of sustained declines for determining a minimum threshold for favourable population size.

We propose a new approach to quantifying a minimum threshold value for the size of an animal population, below which that population might be categorised as having unfavourable status. Under European Union law, the concept of Favourable Conservation Status requires assessment of populations as having favourable or unfavourable status, but quantitative methods for such assessments have not yet been developed. One population threshold that is well established in conservation biology is the minimum viable population (MVP) defined as the size of a small but stable population with an acceptably low risk of extinction within a specified period. Our approach combines this small-population paradigm MVP concept with a multiplier, which is a factor by which the MVP is multiplied to allow for the risk of a sustained future decline. We demonstrate this approach using data on UK breeding bird population sizes. We used 43-year time-series data for 189 species and a qualitative assessment of population trends over almost 200 years for 229 species to examine the prevalence, duration and magnitude of sustained population declines. Our study addressed the problem of underestimation of the duration and magnitude of declines caused by short runs of monitoring data by allowing for the truncation of time series. The multiplier was derived from probability distributions of decline magnitudes within a given period, adjusted for truncation. Over a surveillance period of 100 years, we estimated that there was a 10% risk across species that a sustained population decline of at least sixteen-fold would begin. We therefore suggest that, in this case, a factor of 16 could be used as the multiplier of small-population MVPs to obtain minimum threshold population sizes for favourable status. We propose this 'MVP Multiplier' method as a new and robust approach to obtaining minimum threshold population sizes which integrates the concepts of small-population and declining-population paradigms. The minimum threshold value we propose is intended for use alongside a range of other measures to enable overall assessments of favourable conservation status

Preferred strength and conditioning coaching leadership behaviours of NCAA Division I and II Collegiate student-athletes based on sex

The present study aimed to examine collegiate student-athletesˈpreferences of leadership behaviours in strength and conditioning (S&C) coaching and evaluate differences between athletesˈpreferred leadership behaviours based on participantsˈsex. 145 (male = 80, female = 65) National Collegiate Athletic Association (NCAA) Division I and II student-athletes aged between 18-25 years, with a mean of 3 (SD = ±1) strength and conditioning sessions per week participated in the study. Participants completed an electronic questionnaire involving the athletesˈ preference version of the Revised Leadership Scale for Strength and Conditioning (RLSSC). Summary statistics revealed that the most preferred behaviour was ˈtraining and instructionˈ, median of 4.5 (IQR = 1.0), and the least preferred was ˈautocraticˈ, median of 2.0 (IQR = 0.5). Similar results were observed for both groups. Males preferred autocratic behaviour more than females (male = 2.5, female = 2.0). Statistically significant difference was identified between groups for autocratic behaviour (p = .001). Effect sizes indicated that the magnitude of differences between groups was small or moderate, with the highest value for autocratic behaviour (d = 0.5). The observation of marginal statistically significant difference aligns with previous research, suggesting sex-related differences. However, small and moderate effect sizes indicate that differences are not practically significant enough to encourage distinct coaching approaches. This study sheds light on the preferences of coaching behaviours among student-athletes in strength and conditioning coaching. The findings emphasise the importance of positive psychosocial behaviours such as training and instruction, positive feedback, situational considerations and social support. While there were slight differences between the sexes, results suggested that both groups valued positive coaching behaviours. These findings provide implications for coaching practice and offer a basis for further research to explore leadership coaching behaviours in strength and conditioning

Indirect Effects of Bottom Fishing on the Productivity of Marine Fish

One quarter of marine fish production is caught with bottom trawls and dredges on continental shelves around the world. Towed bottom-fishing gears typically kill 20-50 per cent of the benthic invertebrates in their path, depending on gear type, substrate and vulnerability of particular taxa. Particularly vulnerable are epifaunal species, which stabilize the sediment and provide habitat for benthic invertebrates. To identify the habitats, fisheries or target species most likely to be affected, we review evidence of the indirect effects of bottom fishing on fish production. Recent studies have found differences in the diets of certain species in relation to bottom fishing intensity, thereby linking demersal fish to their benthic habitats at spatial scales of ~10 km. Bottom fishing affects diet composition and prey quality rather than the amount of prey consumed; scavenging of discarded by-catch makes only a small contribution to yearly food intake. Flatfish may benefit from light trawling levels on sandy seabeds, while higher-intensity trawling on more vulnerable habitats has a negative effect. Models suggest that reduction in the carrying capacity of habitats by bottom fishing could lead to lower equilibrium yield and a lower level of fishing mortality to obtain maximum yield. Trawling effort is patchily distributed - small fractions of fishing grounds are heavily fished, while large fractions are lightly fished or unfished. This patchiness, coupled with the foraging behaviour of demersal fish, may mitigate the indirect effects of bottom fishing on fish productivity. Current research attempts to scale up these localized effects to the population level