6,066 research outputs found
The relationship between betting and lottery play: a high frequency time-series analysis
The substitutability of different gambling products is an important concern for any jurisdiction contemplating deregulation of its gambling sector. We apply a novel daily time-series data set of daily turnover from one of Britain's leading bookmakers to analyse potential substitution between lottery play and bookmaker betting. We find some evidence that bettors do substitute away from horse race, dog race and numbers betting when the effective price of lottery tickets is unusually low, i.e. when there is a rollover or Superdraw. This substitution has a highly specific pattern of timing that varies by sector. Our results further suggest that bettors rationally engage in forward-looking substitution within their betting portfolios.
First-principles thermoelasticity of bcc iron under pressure
We investigate the elastic and isotropic aggregate properties of
ferromagnetic bcc iron as a function of temperature and pressure by computing
the Helmholtz free energies for the volume-conserving strained structures using
the first-principles linear response linear-muffin-tin-orbital method and the
generalized-gradient approximation. We include the electronic excitation
contributions to the free energy from the band structures, and phonon
contributions from quasi-harmonic lattice dynamics. We make detailed
comparisons between our calculated elastic moduli and their temperature and
pressure dependences with available experimental and theoretical data.Comment: 5 figures, 2 table
Making Meaning of a Life in Teaching: A Memoir–Writing Project for Seasoned Faculty
The University of Minnesota’s faculty development project, “Making Meaning of a Life in Teaching,” promotes collegiality and enhances self-reflection for those who are cxperienced classroom instructors. Started in October. 2003, this project provides a forum that invites participants to examine specific memories from their teaching lives and to transform those recollections into a written memoir. This chapter explores the use of memoir as an effective tool for faculty development, describes the project’s structure and components, and presents both co-facilitator and participant perspectives on the process and the memoir product
The effect of screening long-range Coulomb interactions on the metallic behavior in two-dimensional hole systems
We have developed a technique utilizing a double quantum well heterostructure
that allows us to study the effect of a nearby ground-plane on the metallic
behavior in a GaAs two-dimensional hole system (2DHS) in a single sample and
measurement cool-down, thereby maintaining a constant disorder potential. In
contrast to recent measurements of the effect of ground-plane screening of the
long-range Coulomb interaction in the insulating regime, we find surprisingly
little effect on the metallic behavior when we change the distance between the
2DHS and the nearby ground-plane.Comment: 5 pages, 4 figures, accepted for publication in PR
Polynomial sequences for bond percolation critical thresholds
In this paper, I compute the inhomogeneous (multi-probability) bond critical
surfaces for the (4,6,12) and (3^4,6) lattices using the linearity
approximation described in (Scullard and Ziff, J. Stat. Mech. P03021),
implemented as a branching process of lattices. I find the estimates for the
bond percolation thresholds, p_c(4,6,12)=0.69377849... and
p_c(3^4,6)=0.43437077..., compared with Parviainen's numerical results of p_c
\approx 0.69373383 and p_c \approx 0.43430621 . These deviations are of the
order 10^{-5}, as is standard for this method, although they are outside
Parviainen's typical standard error of 10^{-7}. Deriving thresholds in this way
for a given lattice leads to a polynomial with integer coefficients, the root
in [0,1] of which gives the estimate for the bond threshold. I show how the
method can be refined, leading to a sequence of higher order polynomials making
predictions that likely converge to the exact answer. Finally, I discuss how
this fact hints that for certain graphs, such as the kagome lattice, the exact
bond threshold may not be the root of any polynomial with integer coefficients.Comment: submitted to Journal of Statistical Mechanic
Perceptions of Facial Expressions of Emotion in Autism Spectrum Disorders: Reading the “minds eye” Using Reverse Correlation
One of the “primary social deficits” of Autism Spectrum Disorders (ASDs) is understanding the emotions of others, yet current literature is inconclusive as to whether individuals with ASD perceive basic facial expressions of emotion differently from typically developed (TD) individuals [Simmons, et al. 2009, Vision Research, 49, 12705-2739] and, if so, which specific emotions are confused
Rotational Evolution During Type I X-Ray Bursts
The rotation rates of six weakly-magnetic neutron stars accreting in low-mass
X-ray binaries have most likely been measured by Type I X-ray burst
observations with RXTE. The nearly coherent oscillations detected during the
few seconds of thermonuclear burning are most simply understood as rotational
modulation of brightness asymmetries on the neutron star surface. We show that,
as suggested by Strohmayer and colleagues, the frequency changes of 1-2 Hz
observed during bursts are consistent with angular momentum conservation as the
burning shell hydrostatically expands and contracts. We calculate how vertical
heat propagation through the radiative outer layers of the atmosphere and
convection affect the coherence of the oscillation. We show that the evolution
of the rotational profile depends strongly on whether the burning layers are
composed of pure helium or mixed hydrogen/helium. Our results help explain the
absence (presence) of oscillations from hydrogen-burning (helium-rich) bursts
that was found by Muno and collaborators.
We investigate angular momentum transport within the burning layers and the
recoupling of the burning layers with the star. We show that the
Kelvin-Helmholtz instability is quenched by the strong stratification, and that
mixing between the burning fuel and underlying ashes by the baroclinic
instability does not occur. However, the baroclinic instability may have time
to operate within the differentially rotating burning layer, potentially
bringing it into rigid rotation.Comment: To appear in The Astrophysical Journal; minor corrections made to
tables and figure
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