Bootstrapping Monte Carlo Tree Search with an Imperfect Heuristic

We consider the problem of using a heuristic policy to improve the value approximation by the Upper Confidence Bound applied in Trees (UCT) algorithm in non-adversarial settings such as planning with large-state space Markov Decision Processes. Current improvements to UCT focus on either changing the action selection formula at the internal nodes or the rollout policy at the leaf nodes of the search tree. In this work, we propose to add an auxiliary arm to each of the internal nodes, and always use the heuristic policy to roll out simulations at the auxiliary arms. The method aims to get fast convergence to optimal values at states where the heuristic policy is optimal, while retaining similar approximation as the original UCT in other states. We show that bootstrapping with the proposed method in the new algorithm, UCT-Aux, performs better compared to the original UCT algorithm and its variants in two benchmark experiment settings. We also examine conditions under which UCT-Aux works well.Comment: 16 pages, accepted for presentation at ECML'1

Helioseismology with PICARD

PICARD is a CNES micro-satellite launched in June 2010 (Thuillier at al. 2006). Its main goal is to measure the solar shape, total and spectral irradiance during the ascending phase of the activity cycle. The SODISM telescope onboard PICARD also allows us to conduct a program for helioseismology in intensity at 535.7 nm (Corbard et al. 2008). One-minute cadence low-resolution full images are available for a so-called medium-$l$ program, and high-resolution images of the limb recorded every 2 minutes are used to study mode amplification near the limb in the perspective of g-mode search. First analyses and results from these two programs are presented here.Comment: 6 pages, 6 figures, Eclipse on the Coral Sea: Cycle 24 Ascending, GONG 2012 / LWS/SDO-5 / SOHO 27, November 12 - 16, 2012, Palm Cove, Queensland. Accepted for publication in Journal of Physics Conference Series on March 1st 201

Hybridizing Constraint Programming and Monte-Carlo Tree Search: Application to the Job Shop problem

International audienceConstraint Programming (CP) solvers classically explore the solution space using tree search-based heuristics. Monte-Carlo Tree-Search (MCTS), a tree-search based method aimed at sequential decision making under uncertainty, simultaneously estimates the reward associated to the sub-trees, and gradually biases the exploration toward the most promising regions. This paper examines the tight combination of MCTS and CP on the job shop problem (JSP). The contribution is twofold. Firstly, a reward function compliant with the CP setting is proposed. Secondly, a biased MCTS node-selection rule based on this reward is proposed, that is suitable in a multiple-restarts context. Its integration within the Gecode constraint solver is shown to compete with JSP-specific CP approaches on difficult JSP instances

Efecto del poliacrilato de sodio (PANa) en la fase de preacondicionamiento del Pinus radiata en vivero

El proyecto tiene como objetivo evaluar el efecto del poliacrilato de Sodio (PANa) en el preacondicionamiento del Pinus radiata D. Don en vivero. El polímero (PANa y celulosa) se mezcló con el sustrato al momento de trasplantar 90 plantones de P. radiata en bolsas de 3000 ml, pero 90 plantas de trasplantaron sin la presencia del polímero (testigo), se evaluaron la calidad morfológica de las plántulas e índices de calidad, mediante un diseño unifactorial. Los resultados muestran que todas las variables evaluadas presentaron diferencias significativas (p ≤ 0,05), con excepción de la altura. Finalmente, el testigo presento un mayor desarrollo morfológico en comparación al tratamiento que contiene el polímero en el sustrato, debió al déficit de humedad al que fue sometido el tratamiento con presencia del polímero. La fase de preacondicionamiento no afectó el desarrollo morfológico del P. radiata en vivero debido al estrés hídrico al que fue sometido los plantones, pero se espera un impacto positivo en campo

Morphological indicators of the quality of live forest species produced in nurseries

El objetivo de la presente investigación fue evaluar los indicadores morfológicos en vivero de cinco especies forestales (Pinus radiata, Alnus acuminata, Escallonia resinosa, Buddleja coriacea y Polylepis incana), en el vivero forestal de la estación experimental agraria “Santa Ana”. Las plántulas fueron producidas durante siete meses en vivero siguiendo los protocolos establecidos en el vivero forestal de la Estación Experimental Agraria “Santa Ana”, las variables morfológicas e índices de calidad de los plantones se analizaron mediante un diseño unifactorial. Los resultados presentaron un efecto significativo (P ≤ 0,05) entre todas las variables evaluados. Además, la Buddleja coriacea presentó un mayor desarrollo en la altura, volumen foliar y peso seco foliar en comparación con las otras especies forestales, mientras el pino presentó un menor desarrollo en altura y diámetro. Los mejores valores de índice de Dickson, índice de contenedor raíz y el índice de robustez, se presentó en el quinual y el pino. Considerando que el índice de calidad predice en mayor exactitud el éxito de la plantación en campo

Indicadores morfológicos de la calidad de cinco especies forestales producidos en vivero

El objetivo de la presente investigación fue evaluar los indicadores morfológicos en vivero de cinco especies forestales (Pinus radiata, Alnus acuminata, Escallonia resinosa, Buddleja coriacea y Polylepis incana), en el vivero forestal de la estación experimental agraria “Santa Ana”. Las plántulas fueron producidas durante siete meses en vivero siguiendo los protocolos establecidos en el vivero forestal de la Estación Experimental Agraria “Santa Ana”, las variables morfológicas e índices de calidad de los plantones se analizaron mediante un diseño unifactorial. Los resultados presentaron un efecto significativo (P ≤ 0,05) entre todas las variables evaluados. Además, la Buddleja coriacea presentó un mayor desarrollo en la altura, volumen foliar y peso seco foliar en comparación con las otras especies forestales, mientras el pino presentó un menor desarrollo en altura y diámetro. Los mejores valores de índice de Dickson, índice de contenedor raíz e el índice de robustez, se presentó en el quinual y el pino. Considerando que el índice de calidad predice en mayor exactitud el éxito de la plantación en campo

Efecto del poliacrilato de sodio (PANa) en la supervivencia e incremento dasométrico de dos especies forestales durante dos años en campo

La problemática del uso de suelos de aptitud forestal en las regiones áridas y semiáridas presenta escasez de lluvias y baja calidad de suelos, por ello, es importante buscar alternativas que permitan superar estos inconvenientes. El presente tiene como objetivo evaluar el efecto del Poliacrilato de Sodio (PANa) de pañales desechables usados en la supervivencia y crecimiento dasométrico de dos especies forestales, durante dos años en campo. Para lo cual se establecieron plantaciones de Pinus radiata D. Don y Polylepis incana bajo tres tratamientos de Poliacrilato de sodio, se evaluó el incremento dasométrico y el porcentaje de supervivencia cada seis meses durante dos años. Para el análisis de las variables se utilizó el diseño estadístico multifactorial. Los resultados indican que el mayor incremento de la altura y diámetro se dio en ambas especies forestales que fueron reforestadas bajo el tratamiento 2 y tratamiento 3, el mayor porcentaje de supervivencia en P. radiata se presentó en el tratamiento B, mientras que en P. incana el testigo presento el mayor porcentaje de supervivencia

MitoGenesisDB: an expression data mining tool to explore spatio-temporal dynamics of mitochondrial biogenesis

Mitochondria constitute complex and flexible cellular entities, which play crucial roles in normal and pathological cell conditions. The database MitoGenesisDB focuses on the dynamic of mitochondrial protein formation through global mRNA analyses. Three main parameters confer a global view of mitochondrial biogenesis: (i) time-course of mRNA production in highly synchronized yeast cell cultures, (ii) microarray analyses of mRNA localization that define translation sites and (iii) mRNA transcription rate and stability which characterize genes that are more dependent on post-transcriptional regulation processes. MitoGenesisDB integrates and establishes cross-comparisons between these data. Several model organisms can be analyzed via orthologous relationships between interspecies genes. More generally this database supports the ‘post-transcriptional operon’ model, which postulates that eukaryotes co-regulate related mRNAs based on their functional organization in ribonucleoprotein complexes. MitoGenesisDB allows identifying such groups of post-trancriptionally regulated genes and is thus a useful tool to analyze the complex relationships between transcriptional and post-transcriptional regulation processes. The case of respiratory chain assembly factors illustrates this point. The MitoGenesisDB interface is available at http://www.dsimb.inserm.fr/dsimb_tools/mitgene/

Searching for p-modes in MOST Procyon data: Another view

Photometry of Procyon obtained by the MOST satellite in 2004 has been searched for p modes by several groups, with sometimes contradictory interpretations. We explore two possible factors that complicate the analysis and may lead to erroneous reports of p modes in these data. Two methods are used to illustrate the role of subtle instrumental effects in the photometry: time-frequency analysis, and a search for regularly spaced peaks in a Fourier spectrum based on the echelle diagramme approach. We find no convincing evidence of a p-mode signal in the MOST Procyon data. We can account for an apparent excess of power close to the p-mode frequency range and signs of structure in an echelle diagramme in terms of instrumental effects.Comment: Article accepted, to appear in A&

Three-dimensional interferometric, spectrometric, and planetary views of Procyon

We used a new realistic 3D radiative-hydrodynamical model atmosphere of Procyon generated with the Stagger Code and synthetic spectra computed with the radiative transfer code Optim3D to re-analyze interferometric and spectroscopic data from the optical to the infrared of Procyon. We compute intensity maps in two optical filters centered at 500 and 800 nm (MARK III) and one infrared filter centered at 2200 nm (VINCI). We constructed stellar disk images accounting for the center-to-limb variations and used them to derive visibility amplitudes and closure phases. We provide 3D limb-darkening coefficients in the optical as well as in the infrared. We show that visibility curves and closure phases show clear deviations from circular symmetry from the 3rd lobe on. These deviations are detectable with current interferometers using closure phases. We derive new angular diameters at different wavelengths with two independent methods based on 3D simulations. We find a diameter_Vinci = 5.390 \pm 0.03 mas that this is confirmed by an independent asteroseismic estimation. The resulting Teff is 6591 K, which is consistent with the infrared flux method determinations. We find also a value of the surface gravity log g = 4.01 \pm 0.03 that is larger by 0.05 dex from literature values. Spectrophotometric comparisons with observations provide very good agreement with the spectral energy distribution and photometric colors, allowing us to conclude that the thermal gradient of the simulation matches fairly well Procyon. Finally, we show that the granulation pattern of a planet hosting Procyon-like star has a non-negligible impact on the detection of hot Jupiters in the infrared using interferometry closure phases. It is then crucial to have a comprehensive knowledge of the host star to directly detect and characterize hot Jupiters. In this respect, RHD simulations are very important to reach this aim.Comment: Accepted for publication on Astronomy and Astrophysics, 14 pages, 12 figure