A Parametric Hierarchical Planner for Experimenting Abstraction Techniques

This paper presents a parametric system, devised and implemented to perform hierarchical planning by delegating the actual search to an external planner (the "parameter") at any level of abstraction, including the ground one. Aimed at giving a better insight of whether or not the exploitation of abstract spaces can be used for solving complex planning problems, comparisons have been made between instances of the hierarchical planner and their non hierarchical counterparts. To improve the significance of the results, three different planners have been selected and used while performing experiments. To facilitate the setting of experimental environments, a novel semi-automatic technique, used to generate abstraction hierarchies starting from ground-level domain descriptions, is also described

A Critical Look at the Abstraction Based on Macro-Operators

Abstraction can be an effective technique for dealing with the complexity of planning tasks. This paper is aimed at assessing and identifying in which cases abstraction can actually speed-up the overall search. In fact, it is well known that the impact of abstraction on the time spent to search for a solution of a planning problem can be positive or negative, depending on several factors -including the number of objects defined in the domain, the branching factor, and the plan length. Experimental results highlight the role of such aspects on the overall performance of an algorithm that performs the search at the ground-level only, and compares them with the ones obtained by enforcing abstraction

PACMAS: A Personalized, Adaptive, and Cooperative MultiAgent System Architecture

In this paper, a generic architecture, designed to support the implementation of applications aimed at managing information among different and heterogeneous sources, is presented. Information is filtered and organized according to personal interests explicitly stated by the user. User pro- files are improved and refined throughout time by suitable adaptation techniques. The overall architecture has been called PACMAS, being a support for implementing Personalized, Adaptive, and Cooperative MultiAgent Systems. PACMAS agents are autonomous and flexible, and can be made personal, adaptive and cooperative, depending on the given application. The peculiarities of the architecture are highlighted by illustrating three relevant case studies focused on giving a support to undergraduate and graduate students, on predicting protein secondary structure, and on classifying newspaper articles, respectively

Notes for an aesthetic approach to walking

Walking has been dealt with from various points of view and by various disciplines and practices, including art and aesthetics. In order to encompass such a phenomenon in an adequate way, an ad hoc terminology has been often coined. Among the terms that have been appositely created, at least four are worth mentioning: ‘odology’ (John Brinckerhoff Jackson), ‘hodological space’ (Kurt Lewin, Jean-Paul Sartre and Otto Friedrich Bollnow), ‘strollology’ (Lucius and Annemarie Burckhardt), and ‘walkscapes’ (Francesco Careri). However distinct and somewhat divergent these may be, the four approaches labeled with these four terms all focus their attention to the relationship between body and space, considering walking as a fundamental moment of the bodily experience of space. For this reason, they can be fruitfully put in relation with the artistic practice of the so-called ‘walking artists’, such as Richard Long, Hamish Fulton, and Michael Höpfner, who pursue the same purposes.peer-reviewe

Molecular mechanism of MBX2319 inhibition of Escherichia coli AcrB multidrug efflux pump and comparison with other inhibitors

Efflux pumps of the resistance nodulation division (RND) superfamily, such as AcrB, make a major contribution to multidrug resistance in Gram-negative bacteria. The development of inhibitors of the RND pumps would improve the efficacy of current and next-generation antibiotics. To date, however, only one inhibitor has been cocrystallized with AcrB. Thus, in silico struc- ture-based analysis is essential for elucidating the interaction between other inhibitors and the efflux pumps. In this work, we used computer docking and molecular dynamics simulations to study the interaction between AcrB and the compound MBX2319, a novel pyranopyridine efflux pump inhibitor with potent activity against RND efflux pumps of Enterobacteriaceae species, as well as other known inhibitors (D13-9001, 1-[1-naphthylmethyl]-piperazine, and phenylalanylarginine-ß-naphthyl-amide) and the binding of doxorubicin to the efflux-defective F610A variant of AcrB. We also analyzed the binding of a sub- strate, minocycline, for comparison. Our results show that MBX2319 binds very tightly to the lower part of the distal pocket in the B protomer of AcrB, strongly interacting with the phenylalanines lining the hydrophobic trap, where the hydrophobic por- tion of D13-9001 was found to bind by X-ray crystallography. Additionally, MBX2319 binds to AcrB in a manner that is similar to the way in which doxorubicin binds to the F610A variant of AcrB. In contrast, 1-(1-naphthylmethyl)-piperazine and phenylalanylarginine-ß-naphthylamide appear to bind to somewhat different areas of the distal pocket in the B protomer of AcrB than does MBX2319. However, all inhibitors (except D13-9001) appear to distort the structure of the distal pocket, impairing the proper binding of substrates

Partnership in teacher education: a theoretical and practical analysis

The aim of this study is to discuss theoretical and practical issues of the partnership in teacher education. A brief background of the debate in the last years is presented, questions about the partnership concept are introduced, the experience of the Brazilian university performing the inter-institutional work is analyzed and an overview is given of how the issue has been addressed in Québec. The current study seeks to note controversies and possible achievements of teachers in their struggles for the greater social approbation of the teaching profession. The research process benefited from documentary analysis, on-site observations and interviews; the last ones carried out in Brazil. The concept of partnership shows ambiguity. On the one hand, it is a strong ally for the implementation of official educational reforms, which puts it in scene between universities and schools. On the other hand, as a collaborative practice between the researchers and the school teachers, it helps to create new theoretical and practical basis for the initial and extended formation of the teaching professionals, in which academic knowledge and experience are articulated. In the case here analyzed, in the Brazilian scenario, the partnership helps to introduce innovations through institutional arrangements with other rationality, by which teachers are valued as collaborators in the processes of teacher training. Thus, we can affirm that the partnership is a relatively recent practice in the field of education, which involves tensions between official interests; and objectives of both collaborative work and collective struggles for the appreciation of the teaching profession of researchers at universities and teachers at schools

An Adaptive Approach for Planning in Dynamic Environments

Planning in a dynamic environment is a complex task that requires several issues to be investigated in order to manage the associated search complexity. In this paper, an adaptive behavior that integrates planning with learning is presented. The former is performed adopting a hierarchical approach, interleaved with execution. The latter, devised to identify new abstract operators, adopts a chunking technique on successful plans. Integration between planning and learning is also promoted by an agent architecture explicitly designed for supporting abstraction