Economic Incentives for Controlling Trade-Related Biological Invasions in the Great Lakes

Ballast water from commercial ships engaged in international trade has been implicated as the primary invasion pathway in over 60 percent of new introductions of invasive alien species (IAS) in the Great Lakes since 1960. Recent policies have recognized that IAS are a form of biological pollution and have become focused on preventing new introductions. Given that emissions-based incentives are infeasible for the case of biological emissions, we investigate the cost-effectiveness of various performance proxy-based and technology-based economic incentives to reduce the threat of new invasions of Ponto-Caspian species in the Great Lakes.aquatic nuisance species, ballast water, uncertainty, risk management, performance-based incentives, environmental subsidies, International Relations/Trade, Resource /Energy Economics and Policy,

Transform methods for precision continuum and control models of flexible space structures

An open loop optimal control algorithm is developed for general flexible structures, based on Laplace transform methods. A distributed parameter model of the structure is first presented, followed by a derivation of the optimal control algorithm. The control inputs are expressed in terms of their Fourier series expansions, so that a numerical solution can be easily obtained. The algorithm deals directly with the transcendental transfer functions from control inputs to outputs of interest, and structural deformation penalties, as well as penalties on control effort, are included in the formulation. The algorithm is applied to several structures of increasing complexity to show its generality

UNTYING A LANCASTRIAN BUNDLE: ECOSYSTEM VALUATION IN WETLAND MITIGATION

A utility-theoretic model indicates that mitigation prices for wetland ecosystems depend on preferences and technical knowledge. Empirical analysis found gaps in respondents' knowledge about such ecosystmes. Valuing wetland types requires dealing with respondents' possible misinformation, by developing tools for informing respondents or by combining service-based valuations with valid technical data.Resource /Energy Economics and Policy,

A SPLIT-SAMPLE TEST OF EXPERIMENTAL DESIGNS FOR STATED CHOICE MODELS OF ENVIRONMENTAL VALUATION

A stated choice model is used to estimate wetland mitigation preferences. In a split sample mail survey, a main effects design is compared to a randomized design. Although randomized designs estimate main effects less efficiently, several policy relevant interactions were found to be significant, suggesting some merits of randomized designs.Environmental Economics and Policy,

TRADABLE RISK PERMITS TO PREVENT FUTURE INTRODUCTIONS OF ALIEN INVASIVE SPECIES INTO THE GREAT LAKES

Alien invasive species contribute to biodiversity loss and cause billions of dollars of economic damage in the Great Lakes. We examine the design and efficiency of a tradeable permit system for biological pollution due to alien species that invade the Great Lakes through the ballast water of commercial ships.Risk and Uncertainty,

Growing massive black holes through super-critical accretion of stellar-mass seeds

The rapid assembly of the massive black holes that power the luminous quasars observed at $z \sim 6-7$ remains a puzzle. Various direct collapse models have been proposed to head-start black hole growth from initial seeds with masses $\sim 10^5\,\rm M_\odot$, which can then reach a billion solar mass while accreting at the Eddington limit. Here we propose an alternative scenario based on radiatively inefficient super-critical accretion of stellar-mass holes embedded in the gaseous circum-nuclear discs (CNDs) expected to exist in the cores of high redshift galaxies. Our sub-pc resolution hydrodynamical simulations show that stellar-mass holes orbiting within the central 100 pc of the CND bind to very high density gas clumps that arise from the fragmentation of the surrounding gas. Owing to the large reservoir of dense cold gas available, a stellar-mass black hole allowed to grow at super-Eddington rates according to the "slim disc" solution can increase its mass by 3 orders of magnitudes within a few million years. These findings are supported by simulations run with two different hydro codes, RAMSES based on the Adaptive Mesh Refinement technique and GIZMO based on a new Lagrangian Godunov-type method, and with similar, but not identical, sub-grid recipes for star formation, supernova feedback, black hole accretion and feedback. The low radiative efficiency of super-critical accretion flows are instrumental to the rapid mass growth of our black holes, as they imply modest radiative heating of the surrounding nuclear environment.Comment: 12 pages, 8 figures, 2 tables. Accepted for publication in MNRA

Stated Choice Experiments with Complex Ecosystem Changes: The Effect of Information Formats on Estimated Variances and Choice Parameters

Stated choice experiments about ecosystem changes involve complex information. This study examines whether the format in which ecosystem information is presented to respondents affects stated choice outcomes. Our analysis develops a utility-maximizing model to describe respondent behavior. The model shows how alternative questionnaire formats alter respondents’ use of filtering heuristics and result in differences in preference estimates. Empirical results from a large-scale stated choice experiment confirm that different format presentations of the same information lead to different preference parameter estimates and error variances. A tabular format results in choice parameter estimates with statistically smaller variances than parameters estimated from data obtained with a text-based format. A text-based format also appears to induce greater use of decision heuristics than does a tabular format.choice experiments, heuristics, stated preference, valuation, web surveys, wetland mitigation, Crop Production/Industries, Demand and Price Analysis,

Far-infrared absorption and the metal-to-insulator transition in hole-doped cuprates

By studying the optical conductivity of BSLCO and YCBCO, we show that the metal-to-insulator transition (MIT) in these hole-doped cuprates is driven by the opening of a small gap at low T in the far infrared. Its width is consistent with the observations of Angle-Resolved Photoemission Spectroscopy in other cuprates, along the nodal line of the k-space. The gap forms as the Drude term turns into a far-infrared absorption, whose peak frequency can be approximately predicted on the basis of a Mott-like transition. Another band in the mid infrared softens with doping but is less sensitive to the MIT.Comment: To be published on Physical Review Letter