Static and Dynamic Portfolio Methods for Optimal Planning: An Empirical Analysis

Combining the complementary strengths of several algorithms through portfolio approaches has been demonstrated to be effective in solving a wide range of AI problems. Notably, portfolio techniques have been prominently applied to suboptimal (satisficing) AI planning. Here, we consider the construction of sequential planner portfolios for domainindependent optimal planning. Specifically, we introduce four techniques (three of which are dynamic) for per-instance planner schedule generation using problem instance features, and investigate the usefulness of a range of static and dynamic techniques for combining planners. Our extensive empirical analysis demonstrates the benefits of using static and dynamic sequential portfolios for optimal planning, and provides insights on the most suitable conditions for their fruitful exploitation

On the muon neutrino mass

During the runs of the PS 179 experiment at LEAR of CERN, we photographed an event of antiproton-Ne absorption, with a complete pi+ -> mu+ ->e+ chain. From the vertex of the reaction a very slow energy pi+ was emitted. The pi+ decays into a mu+ and subsequently the mu+ decays into a positron. At the first decay vertex a muon neutrino was emitted and at the second decay vertex an electron neutrino and a muon antineutrino. Measuring the pion and muon tracks and applying the momentum and energy conservation and using a classical statistical interval estimator, we obtained an experimental upper limit for the muon neutrino mass: m_nu < 2.2 MeV at a 90% confidence level. A statistical analysis has been performed of the factors contributing to the square value of the neutrino mass limit.Comment: 18 pages, 5 eps figure

Detection of antihydrogen annihilations with a Si-micro-strip and pure CsI detector

In 2002, the ATHENA collaboration reported the creation and detection of cold (~15 K) antihydrogen atoms [1]. The observation was based on the complete reconstruction of antihydrogen annihilations, simultaneous and spatially correlated annihilations of an antiproton and a positron. Annihilation byproducts are measured with a cylindrically symmetric detector system consisting of two layers of double sided Si-micro-strip modules that are surrounded by 16 rows of 12 pure CsI crystals (13 x 17.5 x 17 mm^3). This paper gives a brief overview of the experiment, the detector system, and event reconstruction. Reference 1. M. Amoretti et al., Nature 419, 456 (2002).Comment: 7 pages, 5 figures; Proceedings for the 8th ICATPP Conference on Astroparticle, Particle, Space Physics, Detectors and Medical Physics Applications (Como, Italy October 2003) to be published by World Scientific (style file included

Cold-Antimatter Physics

The CPT theorem and the Weak Equivalence Principle are foundational principles on which the standard description of the fundamental interactions is based. The validity of such basic principles should be tested using the largest possible sample of physical systems. Cold neutral antimatter (low-energy antihydrogen atoms) could be a tool for testing the CPT symmetry with high precision and for a direct measurement of the gravitational acceleration of antimatter. After several years of experimental efforts, the production of low-energy antihydrogen through the recombination of antiprotons and positrons is a well-established experimental reality. An overview of the ATHENA experiment at CERN will be given and the main experimental results on antihydrogen formation will be reviewed.Comment: Proceedings of the XLIII International Meeting on Nuclear Physics, Bormio (Italy), March 13-20 (2005). 10 pages, 4 figures, 1 tabl

ATHENA -- First Production of Cold Antihydrogen and Beyond

Atomic systems of antiparticles are the laboratories of choice for tests of CPT symmetry with antimatter. The ATHENA experiment was the first to report the production of copious amounts of cold antihydrogen in 2002. This article reviews some of the insights that have since been gained concerning the antihydrogen production process as well as the external and internal properties of the produced anti-atoms. Furthermore, the implications of those results on future prospects of symmetry tests with antimatter are discussed.Comment: Proc. of the Third Meeting on CPT and Lorentz Symmetry, Bloomington (Indiana), USA, August 2004, edited by V. A. Kostelecky (World Scientific, Singapore). 10 pages, 5 figures, 1 table. Author affiliations cor

Spin physics with antiprotons

New possibilities arising from the availability at GSI of antiproton beams, possibly polarised, are discussed. The investigation of the nucleon structure can be boosted by accessing in Drell-Yan processes experimental asymmetries related to cross-sections in which the parton distribution functions (PDF) only appear, without any contribution from fragmentation functions; such processes are not affected by the chiral suppression of the transversity function $h_1(x)$. Spin asymmetries in hyperon production and Single Spin Asymmetries are discussed as well, together with further items like electric and magnetic nucleonic form factors and open charm production. Counting rates estimations are provided for each physical case. The sketch of a possible experimental apparatus is proposed.Comment: Presented for the proceedings of ASI "Spin and Symmetry", Prague, July 5-10, 2004, to be published in Czech. J. Phys. 55 (2005

History of adversity, health and psychopathology among prisoners: comparison between men and women

Adversity in childhood, risk behaviors and psychopathology are highly prevalent phenomena in inmate populations and have a strong impact on health. Knowing the differences in these variables between the sexes is most important in order to develop appropriate intervention strategies in a prison context. By administering the Socio-demographic and Life History Questionnaire and the Brief Symptoms Inventory, we sought to characterize adverse childhood experiences and relate them to risk behaviors and to psychopathological symptoms, and study the differences between the 65 male and 42 female detainees in Portuguese prison establishments. Men and women report a complex web of adversity in childhood. In a range of ten possible categories, a medium value of 5.05 (DP = 2.63) in total adversity for women and 2.63 (DP = 2.18) for men was encountered, with the prevalence being significantly higher within the female population (Z = -4.33; p = .000). A high prevalence of risk behaviors and psychopathological symptoms was found in both groups, the latter being higher among females. We concluded that the differences between men and women calls for in depth studies in order to provide guidelines for intervention projects in specific populations.Adversidade na infância, comportamentos de risco e psicopatologia são fenómenos muito prevalentes na população reclusa e com forte impacto na saúde. Conhecer as diferenças entre sexos, no que diz respeito a tais variáveis, é de elevada importância no sentido de adequar estraté- gias de intervenção em contexto prisional. Utilizando o Questionário Sociodemográfico e Histó- ria de Vida, o Questionário de Adversidade na Infância e o Brief Symptons Inventory, procuramos caracterizar a adversidade na infância, os comportamentos de risco e as dimensões psicopatológicas, e averiguar as diferenças entre 65 homens e 42 mulheres reclusos em estabelecimentos prisionais Portugueses. Homens e mulheres relatam um quadro complexo de adversidade na infância. Num total possível de dez categorias, verificamos uma média de adversidade total de 5.05 (DP = 2.63) para as mulheres e de 2.63 (DP = 2.18) para os homens, sendo a prevalência significativamente mais elevada junto da população feminina (Z = -4.33; p = .000). Foi ainda encontrada uma elevada prevalência de comportamentos de risco e de sintomatologia psicopatológica em ambos os grupos, sendo esta última superior nas mulheres. Concluímos que as diferenças entre sexos devem ser estudadas para guiarem a adequação dos projetos