Strategic response to a sequence of discrete choice questions

According to neoclassical economic theory, the only stated preference elicitation format that can feasibly be employed in field studies to which truthful response can be the dominant strategy for all respondents is a single binary choice between the status quo and one alternative. In studies where the objective is estimation of preferences for multiple attributes of a good, it is preferred (and, in some cases, necessary) based on econometric considerations, to present respondents with a sequence of choice tasks. Economic theory predicts that utility-maximising respondents may find it optimal to misrepresent their preferences in this elicitation format. In this paper, the effect on stated preferences of expanding the number of choice tasks per respondent from one to four is tested using a split sample treatment in an attribute-based survey relating to the undergrounding of overhead electricity and telecommunications wires in the Australian Capital Territory. We find evidence to suggest that presenting multiple choice tasks per respondent decreases estimates of total willingness to pay and that this effect is related to the ordering of cost levels presented over the sequence of choice tasks. Two behavioural explanations can be advanced - a weak cost minimisation strategy, which implies divergence between stated and true preferences, and a ‘good deal / bad deal’ heuristic, in which stated preferences reflect true preferences that change over the course of the sequence of choice tasks. Preferences stated in the first of a sequence of choice tasks are not significantly different from those stated in the incentive compatible single binary choice task. A key objective of future research will be to establish whether this effect becomes less prevalent as the number of attributes and alternatives per choice task are increased.Choice experiments, willingness to pay, incentive compatibility, strategic behaviour, order effects, underground electricity, Research Methods/ Statistical Methods,

Modelling heterogeneity in response behaviour towards a sequence of discrete choice questions: a probabilistic decision process model

There is a growing body of evidence in the non-market valuation literature suggesting that responses to a sequence of discrete choice questions tend to violate the assumptions typically made by analysts regarding independence of responses and stability of preferences. Decision processes (or heuristics) such as value learning and strategic misrepresentation have been offered as explanations for these results. While a few studies have tested these heuristics as competing hypotheses, none has investigated the possibility that each explains the response behaviour of a subgroup of the population. In this paper, we make a contribution towards addressing this research gap by presenting a probabilistic decision process model designed to estimate the proportion of respondents employing defined heuristics. We demonstrate the model on binary and multinomial choice data sources and find three distinct types of response behaviour. The results suggest that accounting for heterogeneity in response behaviour may be a better way forward than attempting to identify a single heuristic to explain the behaviour of all respondents.Choice experiment, decision process, ordering effects, strategic response, willingness to pay, Research Methods/ Statistical Methods, C25, L94, Q51,

Half-Heusler semiconductors as piezoelectrics

One of the central challenges in materials science is the design of functional and multifunctional materials, in which large responses are produced by applied fields and stresses. A rapidly developing paradigm for the rational design of such materials is based on the first-principles study of a large materials family, the perovskite oxides being the prototypical case. Specifically, first-principles calculations of structure and properties are used to explore the microscopic origins of the functional properties of interest and to search a large space of equilibrium and metastable phases to identify promising candidate systems. In this paper, we use a first-principles rational-design approach to demonstrate semiconducting half-Heusler compounds as a previously-unrecognized class of piezoelectric materials, and to provide guidance for the experimental realization and further investigation of high-performance materials suitable for practical applications.Comment: 5 pages, 3 figues, 3 table

Alice 3.0: Innovations in Teaching Introductory Computing

Alice 3.0 is the latest release of the Alice programming environment developed at CMU by the late Randy Pausch. Over 200 universities use Alice to introduce object-oriented, event-driven programming to students. Alice 3.0 generates its worlds as Java code, and answers the primary criticism that earlier versions of Alice were a sealed environment and did not expose student to computer code. This workshop will guide participants in building an Alice 3.0 program, demonstrate its integration with NetBeans Java IDE, and show how Alice 3.0 code can be modified with Java code in NetBeans. Participants will receive the latest release of the software suite

Motion of the Zinc Ions in Catalysis by a Dizinc Metallo-β-Lactamase

We report rapid-freeze-quench X-ray absorption spectroscopy of a dizinc metallo-β-lactamase (MβL) reaction intermediate. The Zn(II) ions in the dinuclear active site of the S. maltophilia Class B3 MβL move away from each other, by ∼0.3 Å after 10 ms of reaction with nitrocefin, from 3.4 to 3.7 Å. Together with our previous characterization of the resting enzyme and its nitrocefin product complex, where the Zn(II) ion separation relaxes to 3.6 Å, these data indicate a scissoring motion of the active site that accompanies the ring-opening step. The average Zn(II) coordination number of 4.5 in the resting enzyme appears to be maintained throughout the reaction with nitrocefin. This is the first direct structural information available on early stage dizinc metallo-β-lactamase catalysis

Hexagonal ABCABC as semiconducting ferroelectrics

We use a first-principles rational-design approach to identify a previously-unrecognized class of ferroelectric materials in the $P63mc$ LiGaGe structure type. We calculate structural parameters, polarization and ferroelectric well depths both for reported and as-yet hypothetical representatives of this class. Our results provide guidance for the experimental realization and further investigation of high-performance materials suitable for practical applications.Comment: 5 pages, 2 figures, 3 table

Enhancing space transportation: The NASA program to develop electric propulsion

The NASA Office of Aeronautics, Exploration, and Technology (OAET) supports a research and technology (R and T) program in electric propulsion to provide the basis for increased performance and life of electric thruster systems which can have a major impact on space system performance, including orbital transfer, stationkeeping, and planetary exploration. The program is oriented toward providing high-performance options that will be applicable to a broad range of near-term and far-term missions and vehicles. The program, which is being conducted through the Jet Propulsion Laboratory (JPL) and Lewis Research Center (LeRC) includes research on resistojet, arcjets, ion engines, magnetoplasmadynamic (MPD) thrusters, and electrodeless thrusters. Planning is also under way for nuclear electric propulsion (NEP) as part of the Space Exploration Initiative (SEI)

Monolayer MoS2 strained to 1.3% with a microelectromechanical system

We report on a modified transfer technique for atomically thin materials integrated onto microelectromechanical systems (MEMS) for studying strain physics and creating strain-based devices. Our method tolerates the non-planar structures and fragility of MEMS, while still providing precise positioning and crack free transfer of flakes. Further, our method used the transfer polymer to anchor the 2D crystal to the MEMS, which reduces the fabrication time, increases the yield, and allowed us to exploit the strong mechanical coupling between 2D crystal and polymer to strain the atomically thin system. We successfully strained single atomic layers of molybdenum disulfide (MoS2) with MEMS devices for the first time and achieved greater than 1.3% strain, marking a major milestone for incorporating 2D materials with MEMS We used the established strain response of MoS2 Raman and Photoluminescence spectra to deduce the strain in our crystals and provide a consistency check. We found good comparison between our experiment and literature.Published versio