1,721,120 research outputs found
HOMO LUDENS: On the play-element in inductive logic
No full textAs multi-agent systems are becoming more and more important, my strong belief is that it is important to develop a theory of learning agents in strategic processes, a theory that would explain how an agent's beliefs about the environment (which includes the behavior of others insofar as it affects him) evolve until they have come to agree with the actual properties of the environment. This opens new perspectives on the interaction of game theory and learning theory. Modeling asymmetries in knowledge, in abilities and in perceptions of a cooperative situation by different agents is a fascinating challenge for future research, which models of "bounded rationality" have begun to tackle. I am convinced that inductive algorithms will become increasingly important for the development of multi-agents systems. Applications range from economics to social and management sciences and software (computable) agents that interact by negotiation with other agents in the World Wide We
On Two Families of Paradigms of Group-Solvability
No full textWe advance and compare two families of coalitional paradigms of solvability. A coalitional paradigm is distinguished from a "noncoalitional" paradigm primarily by its focus on what groups of agents can achieve, rather than on what individual agents can do, even if cooperating. As a criterion of group formation, our models engage a kind of pairwise, context-dependent coordination between knowledge-based "learning agents", eventually able to communicate the "complete & local" meaning of expressions taken from the set of literals of a common first-order languag
Contextual versus Absolute Coordination - Step One
No full textAn agent who is interested in coordination may also be asked for looking at alternative paradigms of cooperation but "contextual coordination". We do it in this theoretical paper by introducing some paradigms of "absolute", model-theoretic coordination. We argue by using examples and proofs how our paradigms provide an uniform first-order framework to eventually intestigate coordination problems and scenarios of interest in a variety of research areas and domain
THE BIOENERGY AND ENVIRONMENT NEXUS
No full textLe colture energetiche su larga scala, cosi come l’utilizzo di biomassa forestale non residuale, impattano notevolvente i cicli di nutrienti, la biodiversità e l’occupazione di suolo (i tre limiti del pianeta già oltrepassati, oltre al cambiamento climatico) risultando non riconciliabili con uno spazio di operazione sicuro per l’umanità. Occorre piuttosto perseguire fonti di energia rinnovabile che consentano di disaccoppiare il sistema energetico dall’emissione di gas climalteranti ed al contempo richiedano un uso minimo del suolo e limitati impatti sui cicli dei nutrienti e sulla biodiversità.La biomassa forestale residua, la biomassa coltivata in terreni marginali / abbandonati con un basso apporto di nutrienti e la biomass residual proveniente da altri settori dell'economia possono fornire una fonte temporanea di energia per quei settori più difficili da dissociare dai combustibili fossili, in un percorso che porti verso una società in meno dipendente dalle tecnologie di combustione.Large scale dedicated cultivation of bioenergy on fertile arable land or the large scale deployment of biomass from standing forest, with their impact on nutrient cycles, biodiversity and land occupation (the three planet boundaries which are already overtaken beside climate change) is difficult to reconcile with a safe operating space for humanity. Renewable energy sources allowing the decoupling of energy systems from GHG emission requiring a minimal land use, and therefore limited impacts on nutrient cycles and biodiversity, are to be pursued. Residual biomass such as forest harvest residues, biomass cultivated in marginal/abandoned land with low nutrients input, and biowaste from other sectors of the economy may provide a temporary source of energy for those sectors more difficult to decouple from fossil fuels, towards a society less dependent on combustion technologies
Advertising gemes for Web Services
No full textWe advance and discuss a framework suitable to study theoretical implications and practical impact of language evolution and lexicon sharing in an open distributed multi-agent system. In our approach, the assumption of autonomy plays a key role to preserve the opportunity for the agents of local encoding of meanings. We consider the application scenario of Web services, where we conceive the `problem of advertisement' as a matter of sharing a denotational language. We provide a precise formulation of the agents' behavior within a game-theoretical setting. As an important consequence of our "advertising games", we interpret the problem of knowledge interoperability and management in the light of evolutionary dynamics and learning in games. Our methodology is inspired by work in natural language semantics and "language games
Bidirectional Reasoning
No full textThe goal of this paper is to present a formal system FB for bidirectional realoning which integrates forward and backward deduction. FB is proved equivalent to Gentzen's classical system of propositional naturla deduction. FB is the logic od a theorem prover which supports interactive proof construction in general domain
Photoprotective mechanisms in chlorophyll-binding proteins studied by means of electron paramagnetic spectroscopies
Full text linkLight is essential for photosynthesis, and hence in supporting life on earth, but all the steps of the light reactions may lead to the formation of dangerous oxidative species. Chlorophyll a, the green heart of oxygenic photosynthesis, is also its main Achilles' heel, due to a high intersystem crossing (ISC) probability that leads to the production of excited triplet state, an efficient singlet oxygen sensitizer. Photosynthetic organisms have consequently developed several photoprotective mechanisms aimed to avoid photo-oxidative stress originated from the excess of absorbed light, that otherwise would ultimately lead to cell death.
Photoprotection is pivotal for life on Earth, however a full comprehension of the molecular mechanisms is still lacking for several of the processes that photosynthetic organisms employ. The knowledge of the diverse adaptations of the photoprotective response to the various natural conditions in which photosynthetic organisms have evolved promises to highlight the essential characteristics that an efficient mechanism has to display. This understanding of the key molecular requirements for an efficient photoprotection may be exploited for the design of bio-mimetic molecular systems in the fields of artificial photosynthesis, photodynamic therapies and photocatalysis, to make them more durable in virtue of specifically tailored photoprotective mechanisms.
The quickest of the photoprotective processes taking place in natural photosystems relies on the capability of carotenoids to photoprotect the system, either by directly quenching the triplet state of chlorophyll through triplet-triplet energy transfer, or by deactivation of the photosensitized singlet oxygen once it is formed. With the aim of studying this pivotal trait of photosynthetic organisms, in the course of my graduate research I characterized the role of carotenoids in the photoprotection of the two major components of the oxygenic photosynthetic machinery, namely Photosystem I and Photosystem II. Due to the high complexity of the studied samples, consisting of multi-subunit complexes formed by the assembly of Reaction Centers with numerous bound antenna complexes, an Optically Detected Magnetic Resonance (ODMR) approach has been utilized. ODMR, being a double resonance technique, makes possible to disentangle the different triplet state contributions and extract the information regarding the triplet states populated upon illumination in the multi-chromophore complex of interest. A comparative approach, involving either differences in the size of the complexes or mutations, allowed to get insight into the energy transfer pathways and into the differential role that β-carotene and xanthophylls play in the photoprotection of the two photosystems.
With the aim to extend the study of natural photoprotective mechanisms and understand them at a molecular level, we started to work on an unusual chlorophyll binding protein, the Water-Soluble Chlorophyll-binding Protein (WSCP). This research has been conduct in the framework of a joint project between the university of Padova and the university of Mainz. WSCP remarkably differs from the other known chlorophyll-binding proteins, being not involved in the photosynthetic process. WSCP has been shown to be an incredibly stable complex, being able to protect its chlorophylls towards photodamage. Interestingly this protein does not contain carotenoids, in contrast to every other known chlorophyll-binding protein. By combining biochemical and spectroscopic methodologies, we discovered a mechanism for the photoprotection of chlorophylls in WSCP completely new in the landscape of photoprotection We demonstrated that the observed resistance of the WSCP-bound chlorophylls to singlet oxygen damage depends on the localization of the phytyls moieties between the chlorophylls forming a tight dimer in WSCP. We were able to propose a photoprotective mechanism based on the capability of the phytyls to limit the singlet oxygen accessibility to the oxidizable sites of the chlorophylls
Coordination: A model-theoretic perspective
No full textA learning to coordinate paradigm was first introduced in Formal Learning Theory by (Montagna & Osherson, 1999) using the tools of recursion theory. In this paper, we advance and discuss a first-order paradigm of coordination - we call this paradigm of model-coordination. The paradigm is shown to extend Montagna and Osherson's binary players coordinate and if and only if their first-order equivalent agents model-coordinate. An important difference between or paradigm and the proposed by (Montagna & Osherson, 1999) is that in our paradigm agents' preferences and beliefs can be modelle
A distinctive pathway for Triplet-Triplet Energy Transfer photoprotection in Fucoxanthin Chlorophyll-binding Proteins from Cyclotella meneghiniana
No full textFucoxanthin Chlorophyll-binding Proteins (FCPs) are the major light-harvesting complexes of diatoms. In this work, FCPs isolated from Cyclotella meneghiniana have been studied by means of Optically Detected Magnetic Resonance (ODMR) and Time-Resolved Electron Paramagnetic Resonance (TR-EPR), with the aim to characterize the photoprotective mechanism based on triplet-triplet energy transfer (TTET). The spectroscopic properties of the chromophores carrying the triplet state have been interpreted on the basis of a delved analysis of the recently solved crystallographic structures of FCP. The results point toward a photoprotective role for two fucoxanthin molecules exposed to the exterior of the FCP monomers. This shows that FCP has adopted a structural strategy different from that of related light-harvesting complexes from plants and other microalgae, in which the photoprotective role is carried out by two highly conserved carotenoids in the interior of the complex
A Peer-to-Peer Advertising Game
No full textAdvertising plays a key role in service oriented recommendation over a peer-to-peer network. The advertising problem can be considered as the problem of finding a common language to denote the peers' capabilities and needs. Up to now the current approaches to the problem of advertising revealed that the proposed solutions either a#ect the autonomy assumption or do not scale up the size of the network. We explain how an approach based on language games can be e#ective in dealing with the typical issue of advertising: do not require ex-ante agreement and to be responsive to the evolution of the network as an open system. In th
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