Fisher Waves and Front Roughening in a Two-Species Invasion Model with Preemptive Competition

We study front propagation when an invading species competes with a resident; we assume nearest-neighbor preemptive competition for resources in an individual-based, two-dimensional lattice model. The asymptotic front velocity exhibits power-law dependence on the difference between the two species' clonal propagation rates (key ecological parameters). The mean-field approximation behaves similarly, but the power law's exponent slightly differs from the individual-based model's result. We also study roughening of the front, using the framework of non-equilibrium interface growth. Our analysis indicates that initially flat, linear invading fronts exhibit Kardar-Parisi-Zhang (KPZ) roughening in one transverse dimension. Further, this finding implies, and is also confirmed by simulations, that the temporal correction to the asymptotic front velocity is of ${\cal O}(t^{-2/3})$.Comment: 8 pages, 5 figures; Papers on related work can be found at http://www.rpi.edu/~korniss/Researc

A Feature Analysis Framework for Evaluating Multi-Agent System Development Methodologies

This paper proposes a comprehensive and multi-dimensional feature analysis framework for evaluating and comparing methodologies for developing multi-agent systems (MAS). Developed from a synthesis of various existing evaluation frameworks, the novelty of our framework lies in the high degree of its completeness and the relevance of its evaluation criteria. The paper also presents a pioneering effort in identifying the standard steps and concepts to be supported by a MAS-development process and models

Consistency and change in correlates of youth substance use, 1976-1997

https://deepblue.lib.umich.edu/bitstream/2027.42/137878/1/occ49.pd

CE18010

The WESPAS survey program is the consolidation of two existing survey programs carried out by FEAS, the Malin Shelf herring acoustic survey and the boarfish acoustic survey. The Malin Shelf herring acoustic survey has been carried out annually since 2008 and reports on the annual abundance of summer feeding aggregations of herring to the west of Scotland and to the north and west of Ireland from 54°N to 58°30’N. The boarfish survey was conducted from 2011 using a chartered fishing vessel and reported the abundance of spawning aggregations of boarfish from 47°N to 57°N. In 2016 both surveys were combined and since then have been carried out onboard the RV Celtic Explorer over a 42 day period providing synoptic coverage of shelf waters from 47°N northwards to 58°30’N. Age stratified relative stock abundance estimates of boarfish, herring and horse mackerel within the survey area were calculated using acoustic data and biological data from trawl sampling. Stock estimates of boarfish and horse mackerel were submitted to the ICES assessment Working Group for Widely Distributed Stocks (WGWIDE) meeting in August 2018. Herring estimates are submitted to the Herring Assessment Working Group (HAWG) meeting in March every year. Survey performance will be reviewed at the ICES Planning Group meeting for International Pelagic Surveys (WGIPS) meeting in January 2019

Excitation of superconducting qubits from hot non-equilibrium quasiparticles

Superconducting qubits probe environmental defects such as non-equilibrium quasiparticles, an important source of decoherence. We show that "hot" non-equilibrium quasiparticles, with energies above the superconducting gap, affect qubits differently from quasiparticles at the gap, implying qubits can probe the dynamic quasiparticle energy distribution. For hot quasiparticles, we predict a non-neligable increase in the qubit excited state probability P_e. By injecting hot quasiparticles into a qubit, we experimentally measure an increase of P_e in semi-quantitative agreement with the model and rule out the typically assumed thermal distribution.Comment: Main paper: 5 pages, 5 figures. Supplement: 1 page, 1 figure, 1 table. Updated to user-prepared accepted version. Key changes: Supplement added, Introduction rewritten, Figs.2,3,5 revised, Fig.4 adde

Analytic regularity for a singularly perturbed system of reaction-diffusion equations with multiple scales: proofs

We consider a coupled system of two singularly perturbed reaction-diffusion equations, with two small parameters $0< \epsilon \le \mu \le 1$, each multiplying the highest derivative in the equations. The presence of these parameters causes the solution(s) to have \emph{boundary layers} which overlap and interact, based on the relative size of $\epsilon$ and $$. We construct full asymptotic expansions together with error bounds that cover the complete range $0 < \epsilon \leq \mu \leq 1$. For the present case of analytic input data, we derive derivative growth estimates for the terms of the asymptotic expansion that are explicit in the perturbation parameters and the expansion order

Changes in drug use during ages 18-32

https://deepblue.lib.umich.edu/bitstream/2027.42/137887/1/occ39.pd

Rehabilitating antisocial personalities: treatment through self-governance strategies

Offenders with antisocial personality disorder (ASPD) are widely assumed to reject psychotherapeutic intervention. Some commentators, therefore, argue that those with the disorder are better managed in the criminal justice system, where, following the introduction of indeterminate sentences, engagement with psychological treatment is coercively linked to the achievement of parole. By comparison, National Institute of Clinical Excellence guidelines on the management and treatment of ASPD recommend that those who are treatment seeking should be considered for admission to specialist psychiatric hospitals. The rationale is that prison-based interventions are underresourced, and the treatment of ASPD is underprioritised. The justification is that offenders with ASPD can be rehabilitated, if they are motivated. One problem, however, is that little is known about why offenders with ASPD seek treatment or what effect subsequent treatment has on their self-understanding. The aim of this paper is to address these unresolved issues. It draws on the findings of Economic and Social Research Council (ESRC) funded qualitative study examining the experiences of sentenced male offenders admitted to a specialist personality disorder ward within the medium secure estate and the medical practitioners who treat them. The data are analysed with reference to Michel Foucault’s work on governmentality and strategy in power relations. Two arguments are advanced: first, offenders with ASPD are motivated by legal coercive pressures to implement a variety of Foucauldian-type strategies to give the false impression of treatment progress. Second, and related, treatment does not result in changes in self-understanding in the resistive client with ASPD. This presupposes that, in respect of this group at least, Foucault was mistaken in his claim that resistive behaviours merely mask the effectiveness of treatment norms over time. Nevertheless, the paper concludes that specialist treatment in the hospital setting can effect changes in the resistive offender’s self-understanding, but not if the completion of treatment results, as is commonplace, in his prison readmission

Scale-Dependent Contributors to River Profile Geometry

Abstract: A range of complex hydraulic and geomorphic processes shape terrestrial landscapes. It remains unclear how these processes act to generate observed drainage networks across scales of interest. To address this issue, we transform observed and synthetic longitudinal river profiles into the spectral domain with a view to interrogating the different scales at which fluvial landscapes are generated. North American river profiles are characterized by red noise (i.e., spectral power, ϕ ∝ k−2, where k is wave number) at wavelengths >100 km and pink noise (ϕ ∝ k−1) at shorter wavelengths. This observation suggests that river profile geometries are scale‐dependent and using small‐scale observations to develop a general understanding of large‐scale landscape evolution is not straightforward. At wavelengths >100 km, river profile geometries appear to be controlled by smoothly varying patterns of regional uplift and slope‐dependent incision. Landscape simulations, based upon stream power that are externally forced by regional uplift do not exhibit a spectral transition from red to pink noise because these simulations do not incorporate heterogeneous erodibility. Spectral analysis of erodibility extracted from patterns of lithologic variation along river profiles suggests that the missing spectral transition is accounted for by heterogeneous substrates, which are characterized by white or blue noise (ϕ ∝ k0 or k1). Our results have implications for the way by which rivers record large‐scale tectonic forcing while incising through complex lithologic patterns