3,788 research outputs found

    Decision-making and problem-solving methods in automation technology

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    The state of the art in the automation of decision making and problem solving is reviewed. The information upon which the report is based was derived from literature searches, visits to university and government laboratories performing basic research in the area, and a 1980 Langley Research Center sponsored conferences on the subject. It is the contention of the authors that the technology in this area is being generated by research primarily in the three disciplines of Artificial Intelligence, Control Theory, and Operations Research. Under the assumption that the state of the art in decision making and problem solving is reflected in the problems being solved, specific problems and methods of their solution are often discussed to elucidate particular aspects of the subject. Synopses of the following major topic areas comprise most of the report: (1) detection and recognition; (2) planning; and scheduling; (3) learning; (4) theorem proving; (5) distributed systems; (6) knowledge bases; (7) search; (8) heuristics; and (9) evolutionary programming

    Conference on Automated Decision-Making and Problem Solving, the Third Day: Issues Discussed

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    A conference held at Langley Research Center in May of 1980 brought together university experts from the fields of Control Theory, Operations Research, and Artificial Intelligence to explore current research in automation from both the perspective of their own particular disciplines and from that of interdisciplinary considerations. Informal discussions from the final day of the those day conference are summarized

    Brain GABA and Glutamate Concentrations Following Chronic Gabapentin Administration: A Convenience Sample Studied During Early Abstinence From Alcohol.

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    Gabapentin (GBP), a GABA analog that may also affect glutamate (Glu) production, can normalize GABA and Glu tone during early abstinence from alcohol, effectively treating withdrawal symptoms and facilitating recovery. Using in vivo magnetic resonance spectroscopy, we tested the degree to which daily GBP alters regional brain GABA and Glu levels in short-term abstinent alcohol-dependent individuals. Regional metabolite levels were compared between 13 recently abstinent alcohol-dependent individuals who had received daily GBP for at least 1 week (GBP+) and 25 matched alcohol-dependent individuals who had not received GBP (GBP-). Magnetic resonance spectra from up to five different brain regions were analyzed to yield absolute GABA and Glu concentrations. GABA and Glu concentrations in the parieto-occipital cortex were not different between GBP- and GBP+. Glu levels in anterior cingulate cortex, dorsolateral prefrontal cortex, and basal ganglia did not differ between GBP- and GBP+. However, in a subgroup of individuals matched on age, sex, and abstinence duration, GBP+ had markedly lower Glu in the frontal white matter (WM) than GBP-, comparable to concentrations found in light/non-drinking controls. Furthermore, lower frontal WM Glu in GBP+ correlated with a higher daily GBP dose. Daily GBP treatment at an average of 1,600 mg/day for at least 1 week was not associated with altered cortical GABA and Glu concentrations during short-term abstinence from alcohol, but with lower Glu in frontal WM. GBP for the treatment of alcohol dependence may work through reducing Glu in WM rather than increasing cortical GABA

    Compressing Word Embeddings

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    Recent methods for learning vector space representations of words have succeeded in capturing fine-grained semantic and syntactic regularities using vector arithmetic. However, these vector space representations (created through large-scale text analysis) are typically stored verbatim, since their internal structure is opaque. Using word-analogy tests to monitor the level of detail stored in compressed re-representations of the same vector space, the trade-offs between the reduction in memory usage and expressiveness are investigated. A simple scheme is outlined that can reduce the memory footprint of a state-of-the-art embedding by a factor of 10, with only minimal impact on performance. Then, using the same `bit budget', a binary (approximate) factorisation of the same space is also explored, with the aim of creating an equivalent representation with better interpretability.Comment: 10 pages, 0 figures, submitted to ICONIP-2016. Previous experimental results were submitted to ICLR-2016, but the paper has been significantly updated, since a new experimental set-up worked much bette

    Assessing movements of three buoy line types using DSTmilli Loggers: Implications for entanglements of bottlenose dolphins in the crab pot fishery

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    A study was conducted in October 2006 in the Charleston, South Carolina area to test the movements of three different buoy line types to determine which produced a preferred profile that could reduce the risk of dolphin entanglement. Tests on diamond-braided nylon commonly used in the crab pot fishery were compared with stiffened line of Esterpro and calf types in both shallow and deep water environments using DSTmilli data loggers. Loggers were placed at intervals along the lines to record depth, and thus movements, over a 24 hour period. Three observers viewed video animations and charts created for each of the six trial days from the collected logger data and provided their opinions on the most desirable line type that fit set criteria. A quantitative analysis (ANCOVA) of the data was conducted taking into consideration daily tidal fluctuations and logger movements. Loggers tracking the tides had an r2 value approaching 1.00 and produced little movement other than with the tides. Conversely, r2 values approaching 0.00 were less affected by tidal movement and influenced by currents that cause more erratic movement. Results from this study showed that stiffened line, in particular the medium lay Esterpro type, produced the more desirable profiles that could reduce risk of dolphin entanglement. Combining the observer’s results with the ANCOVA results, Esterpro was chosen nearly 60% of the time as opposed to the nylon line which was only chosen 10% of the time. ANCOVA results showed that the stiffened lines performed better in both the shallow and deep water environments, while the nylon line only performed better during one trial in a deep water set, most probably due to the increased current velocities experienced that day. (58pp.)(PDF contains 68 pages

    Chiral two-loop pion-pion scattering parameters from crossing-symmetric constraints

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    Constraints on the parameters in the one- and two-loop pion-pion scattering amplitudes of standard chiral perturbation theory are obtained from explicitly crossing-symmetric sum rules. These constraints are based on a matching of the chiral amplitudes and the physical amplitudes at the symmetry point of the Mandelstam plane. The integrals over absorptive parts appearing in the sum rules are decomposed into crossing-symmetric low- and high-energy components and the chiral parameters are finally related to high-energy absorptive parts. A first application uses a simple model of these absorptive parts. The sensitivity of the results to the choice of the energy separating high and low energies is examined with care. Weak dependence on this energy is obtained as long as it stays below ~560 MeV. Reliable predictions are obtained for three two-loop parameters.Comment: 23 pages, 4 figures in .eps files, Latex (RevTex), our version of RevTex runs under Latex2.09, submitted to Phys. Rev. D,minor typographical corrections including the number at the end of the abstract, two sentences added at the end of Section 5 in answer to a referee's remar

    Identifying Retweetable Tweets with a Personalized Global Classifier

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    In this paper we present a method to identify tweets that a user may find interesting enough to retweet. The method is based on a global, but personalized classifier, which is trained on data from several users, represented in terms of user-specific features. Thus, the method is trained on a sufficient volume of data, while also being able to make personalized decisions, i.e., the same post received by two different users may lead to different classification decisions. Experimenting with a collection of approx.\ 130K tweets received by 122 journalists, we train a logistic regression classifier, using a wide variety of features: the content of each tweet, its novelty, its text similarity to tweets previously posted or retweeted by the recipient or sender of the tweet, the network influence of the author and sender, and their past interactions. Our system obtains F1 approx. 0.9 using only 10 features and 5K training instances.Comment: This is a long paper version of the extended abstract titled "A Personalized Global Filter To Predict Retweets", of the same authors, which was published in the 25th ACM UMAP conference in Bratislava, Slovakia, in July 201

    A systematic review and meta-analysis of school and cognitive function domains of health-related quality of life measures for children and young adults with congenital heart disease

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    \ua9 2023 The Authors. Birth Defects Research published by Wiley Periodicals LLC.Background: Research on cognitive and school functioning domains of health-related quality of life (HRQOL) for children and adolescents with congenital heart disease (CHD) presents inconsistencies. Objectives: To summarize and synthesize data on school and cognitive function domains of HRQOL for children and young people (CYP) with CHD. Methods: Five electronic databases MEDLINE, Scopus, PsycINFO, EMBASE, ERI, and citations were systematically searched. We included original-research articles reporting the cognitive and school function domains of HRQOL for children and young people with CHD (child and parent reports included). Both fixed and random-effects meta-analyses were performed to estimate pooled mean test scores for cognitive and school function. A total of 34 studies met our inclusion criteria and were synthesized narratively, 17 studies were included in formal meta-analyses. Results: Self-reported cognitive function was lower for children and young people with CHD than healthy controls (SMD −0.28 (−0.42, −0.15)). Parental reports demonstrated similar results to self-reports (SMD −0.54 (−0.91, −0.18)). School function was lower in children and young people with CHD compared with healthy controls in self-reported (SMD −0.30 (−0.48, −0.13)) and parent reported HRQOL (SMD −0.49 (0.64, −0.36)). Self-reported school function domain scores were lower for young (<8 years) (SMD −0.65 (−1.32, 0.03)) and older children (8–18 years) (SMD −0.25 (−0.47, −0.03)) with CHD than their peers. Similarly, parents reported lower school function domain scores for young (<8 years) (SMD −0.68 (−1.29, −0.07)) and older (8–18 years) (SMD −0.46 (−068, −0.25)) children with CHD than typically developing peers. Conclusion: Children born with CHD may experience lower cognitive and school function HRQOL scores than healthy controls (self and proxy-report). This is consistent with a subgroup meta-analysis of young (<8 years) and older (8 years old or more) children with CHD reporting lower school function scores compared to controls

    Chiral Perturbation Theory, the 1/Nc{1/N_c} expansion and Regge behaviour determine the structure of the lightest scalar meson

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    The leading 1/Nc1/N_c behaviour of Unitarised Chiral Perturbation Theory distinguishes the nature of the ρ\rho and the σ\sigma. At one loop order the ρ\rho is a qˉq{\bar q}q meson, while the σ\sigma is not. However, semi-local duality between resonances and Regge behaviour cannot be satisfied for larger NcN_c, if such a distinction holds. While the σ\sigma at Nc=3N_c=3 is inevitably dominated by its di-pion component, Unitarised Chiral Perturbation Theory beyond one loop order reveals that as NcN_c increases above 6-8, the σ\sigma has a sub-dominant qˉq{\bar q}q fraction up at 1.2 GeV. Remarkably this ensures semi-local duality is fulfilled for the range of Nc15N_c \lesssim 15, where the unitarisation procedure adopted applies.Comment: 22 pages, 8 figures. Version to be published in Physical Review

    Building the Full Fermion-Photon Vertex of QED by Imposing Multiplicative Renormalizability of the Schwinger-Dyson Equations for the Fermion and Photon Propagators

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    In principle, calculation of a full Green's function in any field theory requires knowledge of the infinite set of multi-point Green's functions, unless one can find some way of truncating the corresponding Schwinger-Dyson equations. For the fermion and boson propagators in QED this requires an {\it ansatz} for the full three point vertex. Here we illustrate how the properties of gauge invariance, gauge covariance and multiplicative renormalizability impose severe constraints on this fermion-boson interaction, allowing a consistent truncation of the propagator equations. We demonstrate how these conditions imply that the 3-point vertex {\bf in the propagator equations} is largely determined by the behaviour of the fermion propagator itself and not by knowledge of the many higher point functions. We give an explicit form for the fermion-photon vertex, which in the fermion and photon propagator fulfills these constraints to all orders in leading logarithms for massless QED, and accords with the weak coupling limit in perturbation theory at O(α){\cal O}(\alpha). This provides the first attempt to deduce non-perturbative Feynman rules for strong physics calculations of propagators in massless QED that ensures a more consistent truncation of the 2-point Schwinger-Dyson equations. The generalisation to next-to-leading order and masses will be described in a longer publication.Comment: 57 pages, 3 figure
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