8,517 research outputs found

    Discovering Evolutionary Stepping Stones through Behavior Domination

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    Behavior domination is proposed as a tool for understanding and harnessing the power of evolutionary systems to discover and exploit useful stepping stones. Novelty search has shown promise in overcoming deception by collecting diverse stepping stones, and several algorithms have been proposed that combine novelty with a more traditional fitness measure to refocus search and help novelty search scale to more complex domains. However, combinations of novelty and fitness do not necessarily preserve the stepping stone discovery that novelty search affords. In several existing methods, competition between solutions can lead to an unintended loss of diversity. Behavior domination defines a class of algorithms that avoid this problem, while inheriting theoretical guarantees from multiobjective optimization. Several existing algorithms are shown to be in this class, and a new algorithm is introduced based on fast non-dominated sorting. Experimental results show that this algorithm outperforms existing approaches in domains that contain useful stepping stones, and its advantage is sustained with scale. The conclusion is that behavior domination can help illuminate the complex dynamics of behavior-driven search, and can thus lead to the design of more scalable and robust algorithms.Comment: To Appear in Proceedings of the Genetic and Evolutionary Computation Conference (GECCO 2017

    Punctuated Equilibrium in Software Evolution

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    The approach based on paradigm of self-organized criticality proposed for experimental investigation and theoretical modelling of software evolution. The dynamics of modifications studied for three free, open source programs Mozilla, Free-BSD and Emacs using the data from version control systems. Scaling laws typical for the self-organization criticality found. The model of software evolution presenting the natural selection principle is proposed. The results of numerical and analytical investigation of the model are presented. They are in a good agreement with the data collected for the real-world software.Comment: 4 pages, LaTeX, 2 Postscript figure

    Abundances of Disk Planetary Nebulae in M31 and the Radial Oxygen Gradient

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    We have obtained spectra of 16 planetary nebulae in the disk of M31 and determined the abundances of He, N, O, Ne, S and Ar. Here we present the median abundances and compare them with previous M31 PN disk measurements and with PNe in the Milky Way. We also derive the radial oxygen gradient in M31, which is shallower than that in the Milky Way, even accounting for M31's larger disk scale length.Comment: 2 pages, 1 figure, 1 table, to appear in the proceedings of IAU Symposium No. 283, Planetary Nebulae: An Eye to the Futur

    Abundances of PNe in the Outer Disk of M31

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    We present spectroscopic observations and chemical abundances of 16 planetary nebulae (PNe) in the outer disk of M31. The [O III] 4363 line is detected in all objects, allowing a direct measurement of the nebular temperature essential for accurate abundance determinations. Our results show that the abundances in these M31 PNe display the same correlations and general behaviors as Type II PNe in the Milky Way Galaxy. We also calculate photoionization models to derive estimates of central star properties. From these we infer that our sample PNe, all near the peak of the Planetary Nebula Luminosity Function, originated from stars near 2 M_sun. Finally, under the assumption that these PNe are located in M31's disk, we plot the oxygen abundance gradient, which appears shallower than the gradient in the Milky Way.Comment: 48 pages, including 12 figures and 8 tables, accepted by Astrophysical Journa

    EXPLORING PROVIDER PERSPECTIVES TO UNDERSTAND HOW TO BEST INFORM PATIENTS IN SOUTH DAKOTA

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    Patients in rural areas are more likely to experience worse health outcomes than patients in urban or suburban areas. The reasons for this discrepancy are multi-faceted, including inequities in resources and access, as well as differences in the environment. Rural providers understand what education and resources patients are missing as they often interact with patients in multiple contexts. We interviewed rural providers and performed an inductive thematic content analysis of the interviews to shed some insight into what information rural patients would need to be better healthcare advocates for themselves. Three themes emerged from the interview data: health education, access, and preventative care. This study proposes that patient education could be one path towards better health outcomes for this population. We suggest that a patient resource for rural residents would need to include accessible, quickly understood health education, information about healthcare access, discussion about telehealth, and stress the importance of preventative care for this patient population

    Optimization of an Injection Locked Laser System for Cold Neutral Atom Traps

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    Many types of quantum systems are being explored for use in quantum computers. One type of quantum system that shows promise for quantum computing is trapped neutral atoms. They have long coherence times, since they have multiple stable ground states and have minimal coupling with other atoms and their environment, and they can be trapped in arrays, making them individu- ally addressable. Once trapped, they can be initialized and operated on using laser pulses. This experiment utilizes a pinhole diffraction pattern, which can trap atoms in both bright and dark areas. To maximize trap strength, an injection-locked laser amplification system is used to provide a high-power, precisely tunable light source for the diffraction pattern. This amplification system depends on the coupling between a “seed” laser and a “receiving” laser. In previous analyses of the coupling between these two laser diodes, the effects on injection locking when varying temperature and current of both lasers have been shown to be highly nonlinear, and few general trends have been identified. In this project, in order to optimize and better characterize the system, automation of the data-taking and varying parameters was implemented. High efficiency lock zones of laser currents and temperatures were identified, and these locking zones will allow us to create strong atom traps for our experiment

    Drivers\u27 Ed for the Information Highway: A Required Course for MBA Students

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    The paper describes a required MBA course covering business information sources offered in the School of Management of the University of Alaska, Fairbanks. This course is unique in that it focuses on information sources external to the firm that are of use to managers. Course goals, history, contents, and conclusions are described

    YouTube Video Project: A Cool Way to Learn Communication Ethics

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    The millennial generation embraces new technologies as a natural way of accessing and exchanging information, staying connected, and having fun. YouTube, a video-sharing site that allows users to upload, view, and share video clips, is among the latest “cool” technologies for enjoying quick laughs, employing a wide variety of corporate activities, and also communicating relevant, engaging instructional content for today’s students. This article describes a YouTube video class project that is a natural fit with today’s students because it involves cutting-edge social media while addressing a critical component of professional development—communication ethics. This project encourages critical thinking, creativity, and applied learning in a team environment using a “cool” new media tool

    Reactive Quenching Of Od A (2)ÎŁ(+) By H-2: Translational Energy Distributions For H- And D-Atom Product Channels

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    The H- and D-atom products from collisional quenching of OD A (2)Sigma(+) by H-2 are characterized through Doppler spectroscopy using two-photon (2 S-2 \u3c-\u3c- 1 S-2) laser-induced fluorescence. Partial deuteration enables separation of the channel forming H + HOD products, which accounts for 75% of reactive quenching events, from the D + H2O product channel. The Doppler profiles, along with those reported previously for other isotopic variants, are transformed into product translational energy distributions using a robust fitting procedure based on discrete velocity basis functions. The product translational energy distribution for the H- atom channel is strongly peaked at low energy (below 0.5 eV) with a long tail extending to the energetic limit. By contrast, the D-atom channel exhibits a small peak at low translational energy with a distinctive secondary peak at higher translational energy (approximately 1.8 eV) before falling off to higher energy. In both cases, most of the available energy flows into internal excitation of the water products. Similar distributions are obtained upon reanalysis of D- and H- atom Doppler profiles, respectively, from reactive quenching of OH A (2)Sigma(+) by D-2. The sum of the translational energy distributions for H- and D- atom channels is remarkably similar to that obtained for OH A (2)Sigma(+) + H-2, where the two channels cannot be distinguished from one another. The product translational energy distributions from reactive quenching are compared with those obtained from a previous experiment performed at higher collision energy, quasiclassical trajectory calculations of the post-quenching dynamics, and a statistical model. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3644763
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