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Evolving graphs: dynamical models, inverse problems and propagation
Applications such as neuroscience, telecommunication, online social networking,
transport and retail trading give rise to connectivity patterns that change over time.
In this work, we address the resulting need for network models and computational
algorithms that deal with dynamic links. We introduce a new class of evolving
range-dependent random graphs that gives a tractable framework for modelling and
simulation. We develop a spectral algorithm for calibrating a set of edge ranges from
a sequence of network snapshots and give a proof of principle illustration on some
neuroscience data. We also show how the model can be used computationally and
analytically to investigate the scenario where an evolutionary process, such as an
epidemic, takes place on an evolving network. This allows us to study the cumulative
effect of two distinct types of dynamics
Any-order propagation of the nonlinear Schroedinger equation
We derive an exact propagation scheme for nonlinear Schroedinger equations.
This scheme is entirely analogous to the propagation of linear Schroedinger
equations. We accomplish this by defining a special operator whose algebraic
properties ensure the correct propagation. As applications, we provide a simple
proof of a recent conjecture regarding higher-order integrators for the
Gross-Pitaevskii equation, extend it to multi-component equations, and to a new
class of integrators.Comment: 10 pages, no figures, submitted to Phys. Rev.
Overlap of heritable influences between Cannabis Use Disorder, frequency of use and opportunity to use cannabis: Trivariate twin modelling and implications for genetic design
Background: The genetic component of Cannabis Use Disorder may overlap with influences acting more generally on early stages of cannabis use. This paper aims to determine the extent to which genetic influences on the development of cannabis abuse/dependence are correlated with those acting on the opportunity to use cannabis and frequency of use. Methods: A cross-sectional study of 3303 Australian twins, measuring age of onset of cannabis use opportunity, lifetime frequency of cannabis use, and lifetime DSM-IV cannabis abuse/dependence. A trivariate Cholesky decomposition estimated additive genetic (A), shared environment (C) and unique environment (E) contributions to the opportunity to use cannabis, the frequency of cannabis use, cannabis abuse/dependence, and the extent of overlap between genetic and environmental factors associated with each phenotype. Results: Variance components estimates were A = 0.64 [95% confidence interval (CI) 0.58–0.70] and E = 0.36 (95% CI 0.29–0.42) for age of opportunity to use cannabis, A = 0.74 (95% CI 0.66–0.80) and E = 0.26 (95% CI 0.20–0.34) for cannabis use frequency, and A = 0.78 (95% CI 0.65–0.88) and E = 0.22 (95% CI 0.12–0.35) for cannabis abuse/dependence. Opportunity shares 45% of genetic influences with the frequency of use, and only 17% of additive genetic influences are unique to abuse/dependence from those acting on opportunity and frequency. Conclusions: There are significant genetic contributions to lifetime cannabis abuse/dependence, but a large proportion of this overlaps with influences acting on opportunity and frequency of use. Individuals without drug use opportunity are uninformative, and studies of drug use disorders must incorporate individual exposure to accurately identify aetiology
What Provides Justification for Cheating:Producing or Observing Counterfactuals?
When people can profit financially by lying, they do so to the extent to which they can justify their lies. One type of justification is the observation and production of desirable counterfactual information. Here, we disentangle observing and producing of desired counterfactuals and test whether the mere observation is sufficient or whether one actually needs to produce the information in order to justify lying. By employing a modified version of the Die-Under-Cup task, we ask participants to privately roll a die three times and to report the outcome of the first die roll (with higher values corresponding to higher payoffs). In all three conditions, participants produce (roll the die) and observe the first die roll, which is relevant for pay. We manipulate whether participants produce and observe versus only observe the second and third die roll outcomes, which are both irrelevant for pay. Results reveal that people lie to the same extent—when producing and observing the counterfactuals, and when merely observing them. It seems that merely observing counterfactual information is sufficient to allow people to use this information to justify their lies. We further test whether creativity and moral disengagement are associated with dishonesty and replicate the finding showing that unethical behavior increases with creativity
Reducing drug related deaths : a pre-implementation assessment of knowledge,barriers and enablers for naloxone distribution through general practice
Peer reviewedPublisher PD
Products, coproducts and singular value decomposition
Products and coproducts may be recognized as morphisms in a monoidal tensor
category of vector spaces. To gain invariant data of these morphisms, we can
use singular value decomposition which attaches singular values, ie generalized
eigenvalues, to these maps. We show, for the case of Grassmann and Clifford
products, that twist maps significantly alter these data reducing degeneracies.
Since non group like coproducts give rise to non classical behavior of the
algebra of functions, ie make them noncommutative, we hope to be able to learn
more about such geometries. Remarkably the coproduct for positive singular
values of eigenvectors in yields directly corresponding eigenvectors in
A\otimes A.Comment: 17 pages, three eps-figure
Mirror formation control in the vicinity of an asteroid
Two strategies are presented for the positioning and control of a spacecraft formation designed to focus sunlight onto a point on the surface of asteroid, thereby sublimating the material and ejecting debris creating thrust. In the first approach, the formation is located at artficial equilibrium points around the asteroid and controlled using the force from the solar radiation pressure. The second approach determines the optimal periodic formation orbits, subject to the gravitational perturbations from the asteroid, the solar radiation pressure and the control acceleration derived from a control law
On the Matter of Time
Drawing on several disciplinary areas, this article considers diverse cultural concepts of time, space, and materiality. It explores historical shifts in ideas about time, observing that these have gone full circle, from visions in which time and space were conflated, through increasingly divergent linear understandings of the relationship between them, to their reunion in contemporary notions of space-time. Making use of long-term ethnographic research and explorations of the topic of Time at Durham University’s Institute of Advanced Study (2012–13), the article considers Aboriginal Australian ideas about relationality and the movement of matter through space and time. It asks why these earliest explanations of the cosmos, though couched in a wholly different idiom, seem to have more in common with the theories proposed by contemporary physicists than with the ideas that dominated the period between the Holocene and the Anthropocene. The analysis suggests that such unexpected resonance between these oldest and newest ideas about time and space may spring from the fact that they share an intense observational focus on material events. Comparing these vastly different but intriguingly compatible worldviews meets interdisciplinary aims in providing a fresh perspective on both of them
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