Learning Mazes with Aliasing States: An LCS Algorithm with Associative Perception

Learning classifier systems (LCSs) belong to a class of algorithms based on the principle of self-organization and have frequently been applied to the task of solving mazes, an important type of reinforcement learning (RL) problem. Maze problems represent a simplified virtual model of real environments that can be used for developing core algorithms of many real-world applications related to the problem of navigation. However, the best achievements of LCSs in maze problems are still mostly bounded to non-aliasing environments, while LCS complexity seems to obstruct a proper analysis of the reasons of failure. We construct a new LCS agent that has a simpler and more transparent performance mechanism, but that can still solve mazes better than existing algorithms. We use the structure of a predictive LCS model, strip out the evolutionary mechanism, simplify the reinforcement learning procedure and equip the agent with the ability of associative perception, adopted from psychology. To improve our understanding of the nature and structure of maze environments, we analyze mazes used in research for the last two decades, introduce a set of maze complexity characteristics, and develop a set of new maze environments. We then run our new LCS with associative perception through the old and new aliasing mazes, which represent partially observable Markov decision problems (POMDP) and demonstrate that it performs at least as well as, and in some cases better than, other published systems

Molecular-orbital theory for the stopping power of atoms in the low velocity regime:the case of helium in alkali metals

A free-parameter linear-combination-of-atomic-orbitals approach is presented for analyzing the stopping power of slow ions moving in a metal. The method is applied to the case of He moving in alkali metals. Mean stopping powers for He present a good agreement with local-density-approximation calculations. Our results show important variations in the stopping power of channeled atoms with respect to their mean values.Comment: LATEX, 3 PostScript Figures attached. Total size 0.54

A feasibility randomized controlled trial of a guided workbook intervention to support work-related goals among cancer survivors in the UK

Objectives: Employment following illness is associated with better physical and psychological functioning. This study aimed to assess the feasibility and acceptability of a theoretically-led workbook intervention designed to support cancer patients returning to work. Design: Parallel-group randomized controlled trial with embedded qualitative interviews Setting: Oncology clinics within four English National Health Service Trusts Participants: Patients who had received a diagnosis of breast, gynecological, prostate or colorectal cancer and who were at least 2 weeks post-treatment initiation. Intervention: A self-guided WorkPlan workbook designed to support cancer patients to return to work with fortnightly telephone support calls to discuss progress. The control group received treatment as usual, and were offered the workbook at the end of their 12-month follow-up. Outcome measures: We assessed aspects of feasibility including eligibility, recruitment, data collection, attrition, feasibility of the methodology, acceptability of the intervention and potential to calculate cost-effectiveness. Results: The recruitment rate of eligible patients was 44%; 68 participants consented and 58 (85%) completed baseline measures. Randomization procedures were acceptable, data collection methods (including cost-effectiveness data) were feasible and the intervention was acceptable to participants. Retention rates at six and 12 months follow-up were 72% and 69% respectively. At 6-month follow-up 30% of the usual care group had returned to full or part-time work (including phased return to work) compared to 43% of the intervention group. At 12-months the percentages were 47% (usual care) and 68% (intervention). Conclusions: The findings confirm the feasibility of a definitive trial, although further consideration needs to be given to increasing the participation rates among men and Black and ethnic minority patients diagnosed with cancer

Physical and emotional nourishment: Food as the embodied component of loving care of elderly family relatives

Purpose This purpose of this study is to examine the fluidity of family life which continues to attract attention. This is increasingly significant for the intergenerational relationship between adult children and their elderly parents. Using practice theory, the aims are to understand the role of food in elderly families and explore how family practices are maintained when elderly transition into care. Design/methodology/approach A phenomenological research approach was used as the authors sought to build an understanding of the social interactions between family and their lifeworld. Findings This study extends theory on the relationship between the elderly parent and their family and explores through practice theory how families performed their love, how altered routines and long standing rituals provided structure to the elderly relatives and how care practices were negotiated as the elderly relatives transitioned from independence to dependence and towards care. A theoretical framework is introduced that provides guidance for the transition stages and the areas for negotiation. Research limitations/implications This research has implications for food manufacturers and marketers, as the demand for healthy food for the elderly is made more widely available, healthy and easy to prepare. The limitations of the research are due to the sample located in East Yorkshire only. Practical implications This research has implications for brand managers of food manufacturers and supermarkets that need to create product lines that target this segment by producing healthy, convenience food. Social implications It is also important for health and social care policy as the authors seek to understand the role of food, family and community and how policy can be devised to provide stability in this transitional and uncertain lifestage. Originality/value This research extends the body of literature on food and the family by focussing on the elderly cared for and their family. The authors show how food can be construed as loving care, and using practice theory, a theoretical framework is developed that can explain the transitions and how the family negotiates the stages from independence to dependence

Physical and emotional nourishment: Food as the embodied component of loving care of elderly family relatives

Purpose This purpose of this study is to examine the fluidity of family life which continues to attract attention. This is increasingly significant for the intergenerational relationship between adult children and their elderly parents. Using practice theory, the aims are to understand the role of food in elderly families and explore how family practices are maintained when elderly transition into care. Design/methodology/approach A phenomenological research approach was used as the authors sought to build an understanding of the social interactions between family and their lifeworld. Findings This study extends theory on the relationship between the elderly parent and their family and explores through practice theory how families performed their love, how altered routines and long standing rituals provided structure to the elderly relatives and how care practices were negotiated as the elderly relatives transitioned from independence to dependence and towards care. A theoretical framework is introduced that provides guidance for the transition stages and the areas for negotiation. Research limitations/implications This research has implications for food manufacturers and marketers, as the demand for healthy food for the elderly is made more widely available, healthy and easy to prepare. The limitations of the research are due to the sample located in East Yorkshire only. Practical implications This research has implications for brand managers of food manufacturers and supermarkets that need to create product lines that target this segment by producing healthy, convenience food. Social implications It is also important for health and social care policy as the authors seek to understand the role of food, family and community and how policy can be devised to provide stability in this transitional and uncertain lifestage. Originality/value This research extends the body of literature on food and the family by focussing on the elderly cared for and their family. The authors show how food can be construed as loving care, and using practice theory, a theoretical framework is developed that can explain the transitions and how the family negotiates the stages from independence to dependence

Technology as 'Applied Science': a Serious Misconception that Reinforces Distorted and Impoverished Views of Science

The current consideration of technology as 'applied science', this is to say, as something that comes 'after' science, justifies the lack of attention paid to technology in science education. In our paper we question this simplistic view of the science-technology relationship, historically rooted in the unequal appreciation of intellectual and manual work, and we try to show how the absence of the technological dimension in science education contributes to a na¿ ve and distorted view of science which deeply affects the necessary scientific and technological literacy of all citizens

Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

The $B^0$-$\bar B^0$ oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives $\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)}$ ps$^{-1}$.Comment: 7 pages, 1 figure, submitted to Physical Review Letter

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

The Nucleon's Virtual Meson Cloud and Deep Inelastic Lepton Scattering

We address the question whether the nucleon's antiquark sea can be attributed entirely to its virtual meson cloud and, in essence, whether there exists a smooth transition between hadronic and quark-gluon degrees of freedom. We take into account contributions from $\pi$ and $K$ mesons and compare with the nucleon's antiquark distributions which serve as a non-perturbative input to the QCD evolution equations. We elucidate the different behavior in the flavor singlet and non-singlet channels and study the dependence of our results on the scale $Q^2$. The meson-nucleon cut-offs that we determine give not only an indication on the size of the region within which quarks are confined in a nucleon, but we find that the scale of these form factors is closely related to the four-momentum transfer, $Q^2$, where gluons are resolved by a high energy probe, and that large meson loop momenta, $|{\bf k}| \approx 0.8$ GeV, contribute significantly to the sea quark distributions. While the agreement of our calculations with data-based parametrizations is satisfactory and scale independent for the flavor breaking share of the nucleon's antiquark sea, the flavor singlet component is quite poorly described. This hints the importance of gluon degrees of freedom.Comment: 34 pages, RevTeX, 6 figures optionally included using epsfig.st