Valuing Forest Ecosystem Services: A Comparison of the Effects of Attitudes and Demographic Characteristics on Willingness to Pay

Environmental Economics and Policy,

Incentive Compatibility in an Attribute-Based Referendum Model

The manner in which WTP survey responses are elicited has received much attention in the nonmarket valuation literature because of the potential bias that may be introduced via alternate response formats. One issue of particular concern is that of incentive compatibility. Several studies have concluded that response formats that present a series of valuation questions are not incentive compatible. While the single dichotomous choice elicitation format reduces the amount of information collected, multiple-bounded elicitation formats may yield biased, unreliable results. Understanding this trade-off can help provide better information on response formats that will elicit incentive compatible responses and therefore provide realistic and policy-relevant information. This research investigates the effect of the number of multinomial choices presented to respondents in an attribute-based referendum (ABR) format on incentive compatibility of responses. Data was collected from two versions of a mail survey that used an attribute-based description of a hypothetical forest easement program in Michigan's Upper Peninsula and a referendum-style choice between the status quo and various forest easement program scenarios. The first version of the survey presented four choice scenarios to respondents while the second version presented only one choice scenario. Results suggest that the multiple-bound response format improves statistical efficiency due to the statistical significance of all estimated parameters. However, this efficiency may also overestimate WTP. The single-bounded response format displays lower statistical efficiency but may reflect more accurate preferences from respondents. Results lead to a rejection of the hypothesis that the number of choices presented to respondents has no effect on results and have implications for the reliability of nonmarket valuation information from multiple-bound response formats in attribute-based referenda models.Research Methods/ Statistical Methods, Resource /Energy Economics and Policy,

Resonant plasma excitation by single-cycle THz pulses

In this paper, an alternative perspective for the generation of millimetric high-gradient resonant plasma waves is discussed. This method is based on the plasma-wave excitation by energetic single-cycle THz pulses whose temporal length is comparable to the plasma wavelength. The excitation regime discussed in this paper is the quasi-nonlinear regime that can be achieved when the normalized vector potential of the driving THz pulse is on the order of unity. To investigate this regime and determine the strength of the excited electric elds, a Particle-In-Cell (PIC) code has been used. It has been found that by exploiting THz pulses with characteristics currently available in laboratory, longitudinal electron plasma waves with electric gradients up to hundreds MV/m can be obtained. The mm-size nature of the resonant plasma wave can be of great utility for an acceleration scheme in which high-brightness electron bunches are injected into the wave to undergo a strong acceleration. The long-size nature of the acceleration bucket with respect to the short length of the electron bunches can be handled in a more robust manner in comparison with the case when micrometric waves are employed

Spectral weight redistribution in (LaNiO3)n/(LaMnO3)2 superlattices from optical spectroscopy

We have studied the optical properties of four (LaNiO$_3$)$_n$/(LaMnO$_3$)$_2$ superlattices (SL) ($n$=2, 3, 4, 5) on SrTiO$_3$ substrates. We have measured the reflectivity at temperatures from 20 K to 400 K, and extracted the optical conductivity through a fitting procedure based on a Kramers-Kronig consistent Lorentz-Drude model. With increasing LaNiO$_3$ thickness, the SLs undergo an insulator-to-metal transition (IMT) that is accompanied by the transfer of spectral weight from high to low frequency. The presence of a broad mid-infrared band, however, shows that the optical conductivity of the (LaNiO$_3$)$_n$/(LaMnO$_3$)$_2$ SLs is not a linear combination of the LaMnO$_3$ and LaNiO$_3$ conductivities. Our observations suggest that interfacial charge transfer leads to an IMT due to a change in valence at the Mn and Ni sites.Comment: Accepted for publication in Phys. Rev. Lett. 5 pages, 5 figure

Manure Handling System Attributes Impact on Manure Management Investment Decisions: A Random Utility Model Approach

Replaced with revised version of paper 07/22/08.Farm Management, Livestock Production/Industries,

Market Segments and Farmer Preferences for Financial Record Systems

farm management, accounting systems, Farm Management,

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

Temperature dependence of the optical spectral weight in the cuprates: Role of electron correlations

We compare calculations based on the Dynamical Mean-Field Theory of the Hubbard model with the infrared spectral weight $W(\Omega,T)$ of La$_{2-x}$Sr$_x$CuO$_4$ and other cuprates. Without using fitting parameters we show that most of the anomalies found in $W(\Omega,T)$ with respect to normal metals, including the existence of two different energy scales for the doping- and the $T$-dependence of $W(\Omega,T)$, can be ascribed to strong correlation effects.Comment: 4 pages, 3 figures. Minor corrections, corrected some typos and added reference