A TEST OF CONTINGENT MARKET BID ELICITATION PROCEDURES FOR PIECEWISE VALUATION

Economists are frequently faced with the task of valuing commodity package components. The valuation of specific impacts of public policies is a case in point. Two contingent market bid elicitation procedures were tested for valuing changes in single components of multicomponent government program. Results of the test suggested that respondents provided more accurate component to piecewise valuation when a two-step bidding approach, rather than a one-step approach was used. Thus, there is evidence that a two-step approach which helps respondents to isolate valuations for package components is perhaps a preferable bid elicitation procedure for piecewise valuation.Research Methods/ Statistical Methods,

Low resting metabolic rate is associated with greater lifespan because of a confounding effect of body fatness

Acknowledgments: This work was funded by the Biotechnology and Biological Sciences Research Council (BBSRC) grant BB/C516228/1 to J.R.S. We thank Jackie Duncan and Sarah Johnston for helping with DNA protocol assays and Lobke Vaanholt for helping with antioxidant enzyme protocols. We are grateful to the staff of the animal house for the care of our animals and to Paula Redman and Peter Thomson who provided technical support for the DLW assays. Open Access: This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Peer reviewedPublisher PD

VADER: A Flexible, Robust, Open-Source Code for Simulating Viscous Thin Accretion Disks

The evolution of thin axisymmetric viscous accretion disks is a classic problem in astrophysics. While models based on this simplified geometry provide only approximations to the true processes of instability-driven mass and angular momentum transport, their simplicity makes them invaluable tools for both semi-analytic modeling and simulations of long-term evolution where two- or three-dimensional calculations are too computationally costly. Despite the utility of these models, the only publicly-available frameworks for simulating them are rather specialized and non-general. Here we describe a highly flexible, general numerical method for simulating viscous thin disks with arbitrary rotation curves, viscosities, boundary conditions, grid spacings, equations of state, and rates of gain or loss of mass (e.g., through winds) and energy (e.g., through radiation). Our method is based on a conservative, finite-volume, second-order accurate discretization of the equations, which we solve using an unconditionally-stable implicit scheme. We implement Anderson acceleration to speed convergence of the scheme, and show that this leads to factor of $\sim 5$ speed gains over non-accelerated methods in realistic problems, though the amount of speedup is highly problem-dependent. We have implemented our method in the new code Viscous Accretion Disk Evolution Resource (VADER), which is freely available for download from https://bitbucket.org/krumholz/vader/ under the terms of the GNU General Public License.Comment: 58 pages, 13 figures, accepted to Astronomy & Computing; this version includes more discussion, but no other changes; code is available for download from https://bitbucket.org/krumholz/vader

Perceptual deficits and inattention in schizophrenia

A number of investigators have found perceptual deficits in schizophrenic subjects. It has also been indicated that those with schizophrenia suffer from reduced attention. This raises the possibility that their perceptual deficits may wholly or in part reflect attentional effects. The present study used computer simulations to examine the potential effects of inattention on performance measures determined with three psychophysical methods: the Two Alternative Forced Choice (2-AFC) Staircase Method, the Two Alternative Forced Choice (2-AFC) Fixed Stimuli Method, and the Yes/No Method. It is shown that both 2-AFC methods are susceptible to attentional effects but, in contrast, the Yes/No Method may allow for the differentiation of attentional effects from sensory sensitivity and subjective criterion effects. The simulations indicate that it may be possible to control for attention effects by using Yes/No Method in combination to a 2AFC method