Temperature response in the physiology and growth of lake trout strains stocked in the Laurentian Great Lakes

Fish stocking programs designed for species rehabilitation aim to match the strains being stocked with the environments the fish will inhabit. The ability of different lake trout Salvelinus namaycush populations to adjust their physiological performance over a broad range of environmental conditions will be advantageous as water temperatures rise with climate warming. This study compares the adaptive physiological potential of 6 strains of lake trout stocked within the Laurentian Great Lakes by comparing growth, metabolic and cardiovascular performance, and organ-system tradeoffs across a temperature gradient. Using a common garden design, lake trout were raised from the embryonic stage until 2 years of age, when they were acclimated to temperatures of 8, 11, 15 and 19 °C before undergoing experiments to test their metabolic performance. For all strains, growth rates showed a dome-shaped response with temperature, peaking at 11 °C and reaching negative rates at 19 °C. For 5 of 6 strains, metabolic rates increased while in all strains cardiovascular performance declined with increasing temperature. Higher metabolic rates at higher temperatures generally came at the cost of slower growth, less investment into gastrointestinal mass, and reduced cardiovascular fitness and investment. Importantly, though, the Seneca strain was unique by showing a reduction of aerobic scope at the highest temperature, possibly indicating increased costs as temperature rises in this smaller-sized, potentially slower pace-of-life strain. However, the overall low interpopulation variability in our study suggests limited diversity in the physiological responses to temperature in strains stocked across the Great Lakes basin.     

On the trade-offs of regulating multiple unpriced externalities with a single instrument: Evidence from biofuel policies

We develop an analytical and numerical model that integrates land, fuel, and food markets to evaluate the welfare implications of the U.S. Renewable Fuel Standard (RFS). Each dollar reduction in the external costs of oil dependency comes at the expense of additional environmental external costs of $0.53. Conditional on the categories of external benefits we consider, the RFS fails a benefit–cost test when excluding the change in the trade balance, with net costs totaling $1.4 billion in 2015. Further, policymakers would have to value the external costs of oil dependency at $1.05 per gallon of gasoline in order for the RFS to pass a benefit–cost test, which is nearly five times larger than central estimates of the oil premium.     

Enabling strategies and impeding factors to urban resilience implementation: A scoping review

Despite growing interest in urban resilience, there is a significant gap between discourse and the capacity to develop resilience in practice. This scoping review assembles and shares evidence and insights from empirical studies of attempts to implement urban resilience published between 2005 and 2017. More precisely, it seeks to identify enabling strategies, impeding factors and trade‐offs in the implementation of urban resilience. Findings are presented along the dimensions of urban resilience detailed in the City Resilience Framework (ARUP/Rockefeller Foundation): Health and Wellbeing, Economy and Society, Infrastructure and Environment, and Leadership and Strategy (which we present as a cross‐cutting theme). While some enabling and impeding factors in implementation are associated with a specific dimension, others are common to all three. Across dimensions, we find that transparent, inclusive and supportive governance reduces the risk of negative impact that resilience implementation will have on communities. Conflicting priorities of managing risk and meeting short‐term needs are found to diminish the potential for transformative resilience action. Integrating risk into planning appears as a promising strategy in all dimensions of resilience. Trade‐offs are found in resilience implementation, and range from adverse effects associated with infrastructure to power imbalances when the power to implement resilience privileges one system level over another.     

Economic trade-offs in acrylic acid reactor design

The acrylic acid process using air oxidation of propylene presents many interesting design trade-offs, particularly in the design of the reactor. The desired and undesired reactions are highly exothermic and very temperature dependent (large activation energies), so a large flowrate of inert water is also fed to the reactor to act as a thermal sink. Propylene conversion increases with temperature and reactor size, but acrylic acid yield decreases with increasing temperature. The heat of reaction is removed by generaing steam, and the steam pressure is an important design optimization variable since it sets low limits on reactor temperature. Using low-pressure steam gives high acrylic acid yield and lower carbon dioxide generation but requires large reactors. Larger air flowrates increase reactor oxygen concentrations, which reduce reactor volume but increase air compression costs.This paper explores the effects of the many design trade-offs on capital investment, energy cost and product selectivity.     

Conceptual beliefs about human values and their implications: Human nature beliefs predict value importance, value trade-offs, and responses to value-laden rhetoric.

Beliefs that may underlie the importance of human values were investigated in 4 studies, drawing on research that distinguishes natural-kind (natural), nominal-kind (conventional), and artifact (functional) beliefs. Values were best characterized by artifact and nominal-kind beliefs, as well as a natural-kind belief specific to the social domain, "human nature" (Studies 1 and 2). The extent to which values were considered central to human nature was associated with value importance in both Australia and Japan (Study 2), and experimentally manipulating human nature beliefs influenced value importance (Study 3). Beyond their association with importance, human nature beliefs predicted participants' reactions to value trade-offs (Study 1) and to value-laden rhetorical statements (Study 4). Human nature beliefs therefore play a central role in the psychology of values. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Zero-sum and frontier trade-offs: an investigation on compromises and compatibilities amongst manufacturing capabilities

This paper examines well-accepted methodologies and rationales used to assert the presence/absence of trade-offs and compatibilities between manufacturing capabilities, and comparisons are made with respect to more recent theoretical developments. By means of a detailed analysis of a representative framework, important limitations and inconsistencies are identified. The proposal for the existence of zero-sum and frontier trade-offs intends to resolve some of those issues. Generally speaking, zero-sum trade-offs are identified by a statistically significant and negative correlation. On the other hand, frontier trade-offs are predicted to be observed after some level of compatibility between different capabilities is achieved. This means that, apart from widely-used probabilistic methodologies such as linear regression/correlation analysis, subsequent deterministic approaches and rationales need to be applied in order to acknowledge the potential existence of frontier trade-offs. These and other implications are discussed in light of previous studies, and suggestions for future research are offered.     

Understanding optimal data gathering in the energy and latency domains of a wireless sensor network

The problem of optimal data gathering in wireless sensor networks (WSNs) is addressed by means of optimization techniques. The goal of this work is to lay the foundations to develop algorithms and techniques that minimize the data gathering latency and at the same time balance the energy consumption among the nodes, so as to maximize the network lifetime. Following an incremental-complexity approach, several mathematical programming problems are proposed with focus on different network performance metrics. First, the static routing problem is formulated for large and dense WSNs. Optimal data-gathering trees are analyzed and the effects of several sensor capabilities and constraints are discussed, e.g., radio power constraints, energy consumption model, and data aggregation functionalities. Then, dynamic re-routing and scheduling are considered. An accurate network model is proposed that captures the tradeoff between the data gathering latency and the energy consumption, by modeling the interactions among the routing, medium access control and physical layers.For each problem, extensive simulation results are provided. The proposed models provide a deeper insight into the problem of timely and energy efficient data gathering. Useful guidelines for the design of efficient WSNs are derived and discussed.     

A bicriterion approach to time/cost trade-offs in scheduling with convex resource-dependent job processing times and release dates

This paper presents a bicriterion analysis of time/cost trade-offs for the single-machine scheduling problem where both job processing times and release dates are controllable by the allocation of a continuously nonrenewable resource. Using the bicriterion approach, we distinguish between our sequencing criterion, namely the makespan, and the cost criterion, the total resource consumed, in order to construct an efficient time/cost frontier. Although the computational complexity of the problem of constructing this frontier remains an open question, we show that the optimal job sequence is independent of the total resource being used; thereby we were able to reduce the problem to a sequencing one. We suggest an exact dynamic programming algorithm for solving small to medium sizes of the problem, while for large-scale problems we present some heuristic algorithms that turned out to be very efficient. Five different special cases that are solvable by using polynomial time algorithms are also presented.     

生态系统服务权衡与协同机制及其在景观规划中的应用

景观规划师常会面临在特定区域协调多种生态系统服务(ESs)间权衡与协同关系的现实需求,而当前针对ESs间权衡与协同关系及其机制研究如何应用于景观规划的研究仍不足。首先,回顾国内外关于ESs间权衡与协同关系研究进展,从形成基础和变化动因两方面揭示其机制,并梳理机制研究的方法与进展。其次,以3类景观规划为例,分析ESs间权衡与协同关系及机制研究可在其中发挥的作用,并结合研究案例探索将其应用于景观规划的途径。研究ESs间权衡与协同关系及机制,能够在景观规划中为实现ESs降权衡升协同提供重要信息：1)在生态功能区划中,能指导ESs目标的分区分配;2)在生态基础设施规划中,能指导空间网络优化方案的制定;3)在生态修复规划中,能指导关键修复区域识别及修复策略的提出。最后,提出应以规划实践为导向展开研究,加强学科合作交流,完善研究方法,并探索整合多种研究成果的有效途径,更好地将ESs间权衡与协同关系及机制研究应用于景观规划。     

A note on ‘beyond the trade-off and cumulative capabilities models: alternative models of operations strategy’

A recent thought provoking paper affirms that in practice, the trade-offs model is not used. In this study, we reanalyse the data based on a more complete understanding of Skinner’s model. Our results indicate that while there may be some evidence of firms that are capable of achieving high performance across a number of manufacturing capabilities in that investigation, there is also plenty of evidence generally consistent with the core tenet of the trade-offs model. We also emphasise that more practical and definitive statements about Skinner’s model must necessarily involve detailed studies of market leading firms, or, individual product/services. Opportunities to move forward on the topic of strategic trade-offs are outlined.