FOREWORD: Special Issue on Trade

International Relations/Trade,

THE POLITICAL ECONOMY OF WATER QUALITY PROTECTION FROM AGRICULTURAL CHEMICALS

Environmental Economics and Policy,

The Coordination and Design of Point-Nonpoint Trading Programs and Agri-Environmental Policies

Agricultural agencies have long offered agri-environmental payments that are inadequate to achieve water quality goals, and many state water quality agencies are considering point-nonpoint trading to achieve the needed pollution reductions. This analysis considers both targeted and nontargeted agrienvironmental payment schemes, along with a trading program which is not spatially targeted. The degree of improved performance among these policies is found to depend on whether the programs are coordinated or not, whether double-dipping (i.e., when farmers are paid twice-once by each program-to undertake particular pollution control actions) is allowed, and whether the agri-environmental payments are targeted. Under coordination, efficiency gains only occur with double-dipping, so that both programs jointly influence farmers' marginal decisions. Without coordination, doubledipping may increase or decrease efficiency, depending on how the agri-environmental policy is targeted. Finally, double-dipping may not solely benefit farmers, but can result in a transfer of agricultural subsidies to point sources.Environmental Economics and Policy,

THE VALUE OF ECOLOGICAL AND ECONOMIC INFORMATION IN WATER QUALITY MANAGEMENT

Replaced with revised version of paper 08/25/03.Environmental Economics and Policy,

THE DESIGN AND COMPARATIVE ECONOMIC PERFORMANCE OF ALTERNATIVE SECOND-BEST POINT/NONPOINT TRADING MARKETS

There is considerable interest in the use of pollution trading between point and nonpoint sources to improve the cost-effectiveness of water pollution control, but little literature to guide the design of trading systems involving nonpoint sources. We explore the design of two types of trading systems that would allow trading among and between point and nonpoint sources.Environmental Economics and Policy,

The application of high temporal resolution data in river catchment modelling and management strategies

Modelling changes in river water quality, and by extension developing river management strategies, has historically been reliant on empirical data collected at relatively low temporal resolutions. With access to data collected at higher temporal resolutions, this study investigated how these new dataset types could be employed to assess the precision and accuracy of two phosphorus (P) load apportionment models (LAMs) developed on lower resolution empirical data. Predictions were made of point and diffuse sources of P across ten different sampling scenarios. Sampling resolution ranged from hourly to monthly through the use of 2000 newly created datasets from high frequency P and discharge data collected from a eutrophic river draining a 9.48 km2 catchment. Outputs from the two LAMs were found to differ significantly in the P load apportionment (51.4% versus 4.6% from point sources) with reducing precision and increasing bias as sampling frequency decreased. Residual analysis identified a large deviation from observed data at high flows. This deviation affected the apportionment of P from diffuse sources in particular. The study demonstrated the potential problems in developing empirical models such as LAMs based on temporally relatively poorly-resolved data (the level of resolution that is available for the majority of catchments). When these models are applied ad hoc and outside an expert modelling framework using extant datasets of lower resolution, interpretations of their outputs could potentially reduce the effectiveness of management decisions aimed at improving water quality

Throughput, Risk and Economic Optimality of Runway Landing

Abstract This paper analyzes the optimal level of operations on a single runway used only for arrivals. Two risks associated with landing procedures are the risk of a wake vortex encounter and the risk of simultaneous runway occupancy. We develop optimization models to maximize successful landing operations while mitigating these risk factors. The risks are mitigated by enforcing go-around procedures when separation distances are too small. In our capacity optimization, we assume that the goaround procedures are strictly enforced (making the operations risk-free) and their execution is absolutely safe. We develop two models as decision support tools which mimic the system dynamics and provide new insights into the landing process. One model maximizes the risk-free throughput (number of successful landings per unit of time) with and without wake-vortex effects. The second model accounts for dollar benefits and go-around costs in optimizing the system operations' level. This model maximizes expected net economic outcome (total dollar benefits minus total go-around costs) by adjusting the rate of landing attempts. Through these models, we calculate the maximum (risk-free) achievable throughput in the system. This provides a new definition of the landing capacity of the runway taking into account the probabilistic behavior of operations. Several numerical examples are given

The SISO CSPI PDG standard for commercial off-the-shelf simulation package interoperability reference models

For many years discrete-event simulation has been used to analyze production and logistics problems in manufactur-ing and defense. Commercial-off-the-shelf Simulation Packages (CSPs), visual interactive modelling environ-ments such as Arena, Anylogic, Flexsim, Simul8, Witness, etc., support the development, experimentation and visua-lization of simulation models. There have been various attempts to create distributed simulations with these CSPs and their tools, some with the High Level Architecture (HLA). These are complex and it is quite difficult to assess how a set of models/CSP are actually interoperating. As the first in a series of standards aimed at standardizing how the HLA is used to support CSP distributed simula-tions, the Simulation Interoperability Standards Organiza-tion’s (SISO) CSP Interoperability Product Development Group (CSPI PDG) has developed and standardized a set of Interoperability Reference Models (IRM) that are in-tended to clearly identify the interoperability capabilities of CSP distributed simulations

The aggregation of cytochrome C may be linked to its flexibility during refolding

Large-scale expression of biopharmaceutical proteins in cellular hosts results in production of large insoluble mass aggregates. In order to generate functional product, these aggregates require further processing through refolding with denaturant, a process in itself that can result in aggregation. Using a model folding protein, cytochrome C, we show how an increase in final denaturant concentration decreases the propensity of the protein to aggregate during refolding. Using polarised fluorescence anisotropy, we show how reduced levels of aggregation can be achieved by increasing the period of time the protein remains flexible during refolding, mediated through dilution ratios. This highlights the relationship between the flexibility of a protein and its propensity to aggregate. We attribute this behaviour to the preferential urea-residue interaction, over self-association between molecules