Limits of end-state planning

Peer reviewedPreprin

Strange Quarks Nuggets in Space: Charges in Seven Settings

We have computed the charge that develops on an SQN in space as a result of balance between the rates of ionization by ambient gammas and capture of ambient electrons. We have also computed the times for achieving that equilibrium and binding energy of the least bound SQN electrons. We have done this for seven different settings. We sketch the calculations here and give their results in the Figure and Table II; details are in the Physical Review D.79.023513 (2009).Comment: Six pages, one figure. To appear in proceedings of the 2008 UCLA coference on dark matter and dark energ

The ⋆\star-value Equation and Wigner Distributions in Noncommutative Heisenberg algebras

We consider the quantum mechanical equivalence of the Seiberg-Witten map in the context of the Weyl-Wigner-Groenewold-Moyal phase-space formalism in order to construct a quantum mechanics over noncommutative Heisenberg algebras. The formalism is then applied to the exactly soluble Landau and harmonic oscillator problems in the 2-dimensional noncommutative phase-space plane, in order to derive their correct energy spectra and corresponding Wigner distributions. We compare our results with others that have previously appeared in the literature.Comment: 19 page

A priming method for investigating the selection of motor responses

We describe a priming method for investigating the mechanisms underlying the selection of motor responses. The empirical question addressed with the method is how the choice reaction time for a response depends on its relationship to a response that the subject was primed to perform. We explore the method in a study of manual response selection where we investigate the effects of requiring that two possible responses use the same finger or hand. A requirement of the method -- that subjects get ready to perform primed responses only -- is not met in some conditions of the experiment. When the two possible responses are made with different hands, it appears that multiple response preparation occurs prior to detection of the reaction signal, whereas when the two possible responses are made with different fingers of the same hand it appears that advance preparation is limited to a single response. This finding implies that subjects engage in different kinds of response preparation depending on the relationship between the alternative possible responses. We discuss the implications of this hypothesis for the priming method introduced here as well as for theories of response selection generally.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23848/1/0000087.pd

Inference with interference between units in an fMRI experiment of motor inhibition

An experimental unit is an opportunity to randomly apply or withhold a treatment. There is interference between units if the application of the treatment to one unit may also affect other units. In cognitive neuroscience, a common form of experiment presents a sequence of stimuli or requests for cognitive activity at random to each experimental subject and measures biological aspects of brain activity that follow these requests. Each subject is then many experimental units, and interference between units within an experimental subject is likely, in part because the stimuli follow one another quickly and in part because human subjects learn or become experienced or primed or bored as the experiment proceeds. We use a recent fMRI experiment concerned with the inhibition of motor activity to illustrate and further develop recently proposed methodology for inference in the presence of interference. A simulation evaluates the power of competing procedures.Comment: Published by Journal of the American Statistical Association at http://www.tandfonline.com/doi/full/10.1080/01621459.2012.655954 . R package cin (Causal Inference for Neuroscience) implementing the proposed method is freely available on CRAN at https://CRAN.R-project.org/package=ci