The mental representation of brief temporal durations, when assessed in standard laboratory conditions, is highly accurate. Here we show that adding or subtracting temporal durations systematically results in strong and opposite biases, namely over-estimation for addition and under-estimation for subtraction. The difference with respect to a baseline temporal reproduction task changed across durations in an operation-specific way and survived correcting for the effect due to operation sign alone, indexing a reliable signature of arithmetic processing on time representation. A second experiment (...) replicated these findings with a different set of stimuli. This novel behavioral marker conceptually mirrors in the time domain the representational momentum found with motion, whereby the estimated spatial position of a visual target is displaced in the direction of motion itself. This momentum effect in temporal arithmetic suggests a striking analogy between time processing and visuospatial processing, which might index the presence of common computational principles. (shrink)

The extracellular‐signal regulated kinases 1/2 (ERK or ERKs) are involved in the regulation of important neuronal functions, including neuronal plasticity in normal and pathological conditions. We present findings that support the notion that the kinetics and localization of ERK are intrinsically linked, in that the duration of ERK activation dictates its subcellular compartmentalization and/or trafficking. The latter, in turn, dictates whether ERK‐expressing cells would enter a program of cell death, survival or differentiation. We summarize experimental data showing that chronic activation (...) of ERK plays a role in the mechanisms that trigger neurodegeneration. We also discuss how MKPs, members of the subclass of dual specificity phosphatases, might be the link between ERK kinetics and its subcellular localization. BioEssays 25:1085–1095, 2003. © 2003 Wiley Periodicals, Inc. (shrink)

The discovery of neurogenesis and neural stem cells (NSC) in the adult CNS has overturned a long‐standing and deep‐routed “dogma” in neuroscience, established at the beginning of the 20th century. This dogma lasted for almost 90 years and died hard when NSC were finally isolated from the adult mouse brain. The scepticism in accepting adult neurogenesis has now turned into a rush to find applications to alleviate or cure the devastating diseases that affect the CNS. Here we highlight a number (...) of methodological, technical and conceptual drawbacks responsible for the historical denial of adult neurogenesis. Furthermore, we discuss old and new issues that need to be faced before NSC or endogenous neurogenesis can safely enter into the doctor's bag for therapies. BioEssays 30:135–145, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

Background Ensuring individual free and informed decision‐making for research participation is challenging. It is thought that preliminarily informing communities through ‘community sensitization’ procedures may improve individual decision‐making. This study set out to assess the relevance of community sensitization for individual decision‐making in research participation in rural Gambia. Methods This anthropological mixed‐methods study triangulated qualitative methods and quantitative survey methods in the context of an observational study and a clinical trial on malaria carried out by the Medical Research Council Unit Gambia. (...) Results/discussion Although 38.7% of the respondents were present during sensitization sessions, 91.1% of the respondents were inclined to participate in the trial when surveyed after the sensitization and prior to the informed consent process. This difference can be explained by the informal transmission of information within the community after the community sensitization, expectations such as the benefits of participation based on previous research experiences, and the positive reputation of the research institute. Commonly mentioned barriers to participation were blood sampling and the potential disapproval of the household head. Conclusion Community sensitization is effective in providing first‐hand, reliable information to communities as the information is cascaded to those who could not attend the sessions. However, further research is needed to assess how the informal spread of information further shapes people's expectations, how the process engages with existing social relations and hierarchies (e.g. local political power structures; permissions of heads of households) and how this influences or changes individual consent. (shrink)

A recent paper by Jakl, Jung and Pultr succeeded for the first time in establishing a very natural link between bilattice logic and the duality theory of d-frames and bitopological spaces. In this paper we further exploit, extend and investigate this link from an algebraic and a logical point of view. In particular, we introduce classes of algebras that extend bilattices, d-frames and N4-lattices to a setting in which the negation is not necessarily involutive, and we study corresponding logics. We (...) provide product representation theorems for these algebras, as well as completeness, algebraizability results for the corresponding logics. (shrink)

A mesure qu'ils avancent dans leur œuvre de prospection, les sémioticiens s'aperçoivent que tout est communication, la langue bien sûr, mais aussi les images, les sons, les objets, les gestes, et que tous ces phénomènes constituent des systèmes de signes qui doivent être étudiés en ramenant chaque message aux codes qui en régissent l'émission et la compréhension. Comprendre les systèmes de signes impose toutefois d'envisager les codes comme des structures, puis de recouvrir à des structures toujours plus vastes, dans un (...) mouvement de régression vers la matrice originelle de toute communication possible, vers un prétendu Code des Codes qui devrait représenter la détermination " naturelle " précédant toute culture. Mais si la sémiotique s'engageait dans cette voie, elle ne pourrait qu'aboutir à la " source " de toute structure possible, forcément non structurée, à ce qu'Umberto Ecco appelle la structure absente. Son livre, tout en refusant ce Code des Codes, essaie de montrer que tout acte communicatif est dominé par la présence massive de codes socialement et historiquement déterminés. La sémiotique découvre ainsi dans la dialectique entre code et message les rapports entre l'univers de signes et l'univers des idéologies, qui se reflètent dans les modes communicatifs préconstitués, et elle relie le monde des choses au monde de la culture, qui formalise les choses non pas pour les reconnaître comme elles sont mais afin de les transformer. Après avoir étudié dans L'œuvre ouverte (1965) les structures des langages expérimentaux de l'art contemporain, Umberto Ecco traite ici l'ensemble des problèmes sémiotiques et ce livre constitue à la fois sa contribution à la recherche en cours et le panorama actuellement le plus vaste et le plus complet sur les préalables constitutifs à toute sémiotique et sur l'état présent du structuralisme. (shrink)

Umberto Eco -- Stephen Jay Gould -- Jean-Claude Carrière -- Jean Delumeau.

Cet article met en question une tendance postmoderne assez répandue: celle de reconstruire abusivement la signification d’un texte du passé, de telle façon que ce texte puisse jouer le rôle d’allié ou d’ennemi dans nos guerres idéologiques. L’exemple choisi c’est un article d’Umberto Eco - «Anti-Porfirio» ainsi qu’un chapitre parallèle de son livre Semiotics and the Philosophy of Language. Selon Eco, le fameux «Arbre de Porphyre» serait une illustration graphique de ce qu’il appelle «pensée forte». Or, cette pensée aurait (...) été minée depuis longtemps - affirme Eco - par la «pensée faible» qu’il retrouve dans la soi-disant «pensée encyclopédique», et ce sont déjà certains textes d’Aristote ou de Thomas d’Aquin, qui en attestent la présence. De plus, Eco pense avoir trouvé dans le Discours préliminaire d’Alembert, oeuvre qui préface l’Encyclopédie française, un devancier de la «pensée faible» postmoderne. Il s’apparente, selon lui, au «rhizome» décrit par G. Deleuze. Aussi cette «pensée encyclopédique» est-elle l’opposé même de la logique incarnée par l’antique «Arbre de Porphyre». L’article tâche de montrer qu’Umberto Eco a beaucoup déformé certaines idées des philosophes mentionnés là-dessus. En effet, il a tendance à discuter les textes pertinents hors de leur contexte métaphysique originaire, tout en en omettant certains aspects décisifs. D’après Eco, Thomas d’Aquin et surtout d’Alembert auraient anticipé le postmodernisme, ce qui, selon moi, n’est pas du tout le cas. Je crois que, en effet, Eco a donné moins une description tant soit peu fidèle d’un passé philosophique qu’une reconstruction relativement abusive de ce passé, légitimant ainsi ses propres vues philosophiques. (shrink)

Dans ses romans « historiques », Umberto Eco revisite, de manière postmoderne, le grand bassin sémantique des « merveilles » de la littérature médiévale et de la Renaissance. Plus spécifiquement, dans L’Île du jour d’avant, il travaille sur la toile de fond de l’imaginaire cosmographique de l’âge des grandes « reconnaissances ». Les aventures du protagoniste suivent un trajet initiatique vers un « centre sacré » de la mappemonde, le méridien zéro. En même temps, les péripéties extérieures sont le (...) corrélatif d’une évolution intérieure, que nous analysons avec les instruments de la psychologie analytique jungienne. La colombe orange qui jaillit de l’île au moment culminant du roman, ayant les caractéristiques d’un Phénix — oiseau de la rédemption et la renaissance — est un symbole de l’accomplissement du personnage, de l’atteinte de son soi mystique. In his “historical” novels, Umberto Eco revisits, in a postmodern manner, the great “semantic basin” of the marvels from medieval and Renaissance literature. In his Island of the Day Before, he makes use of the cosmographic representations of the world from the “Age of Reconnaissance”. The adventures of the character are organized as an initiation journey towards a sacred center of the mappaemundi of the epoch, the Meridian 0. These objective events are the correlative of an internal evolution, which we analyze using concepts from Jungian psychology. The orange dove that springs from the island at the climax of the novel, resembling a classical Phoenix, is a symbol for the character’s realization of the mystique Self. (shrink)

A partire dalla produzione saggistica e letteraria di Umberto Eco, l’articolo analizzerà l’immaginario del Medioevo inteso come culla di ogni genere di millenarismo. La trattazione prenderà avvio dal suo saggio Palinsesto su Beato ; tenendo conto dell’originalità della prospettiva strutturalista di Eco, si confronterà l’ultima riedizione di questo scritto con un quadro bibliografico sul ruolo dell’Apocalisse di San Giovanni in seno alla tradizione occidentale. Il primo riferimento sarà la tesi genealogica di Karl Löwith, il quale nel suo Significato e (...) fine della storia affermò che le moderne filosofie della storia rispondono alla stessa ispirazione millenarista della cultura cristiana. Il secondo confronto sarà con uno dei ritratti dell’eresiarca Fra Dolcino; nella fattispecie, sarà considerata la prospettiva del filosofo socialista Antonio Labriola, elaborata a fine Ottocento per distinguere le applicazioni scientifiche del materialismo storico dai suoi fraintendimenti escatologici. Questi due opposti interlocutori condurranno a problematizzare l’interpretazione del millenarismo per come rappresentato da Umberto Eco ne Il nome della rosa. Il romanzo intende infatti l’apocalittica dolciniana come la prefigurazione del terrorismo degli Anni di Piombo? O si tratta di una mera strizzata d’occhio, un gioco con il lettore, il quale è chiamato a non confidare troppo nella potenza simbolica delle analogie? Considering Umberto Eco’s articles and novels, the paper will examine the imaginary of the Middle Age as the cradle of every kind of millenarianism. The analysis will start from Eco’s essay Palinsesto su Beato. Looking at the originality of his structuralist view, I will compare the last editing of this text with a bibliographical framework about the role of the Apocalypse of St. John in the Western tradition. The first reference will be the genealogical thesis of Karl Löwith, who in Meaning in History affirmed that the modern philosophies of history have the same eschatological aim of the Christian culture. The second comparison will be with a portrait of the medieval heresiarch Fra Dolcino. In this case, I will consider the perspective of the socialist philosopher Antonio Labriola, who elaborated it at the end of the XIX Century to distinguish the scientific applications of historical materialism from his eschatological misinterpretations. These two opposite references will drive me to problematize the representation of millenarianism as it was depicted by Umberto Eco in his The Name of the Rose. Indeed, is Dulcinian millenarianism intended by the novel as a prefiguration of the political terrorism in Italy during the Years of Lead? Or is this only a wink, a joking interaction with the reader, who should be careful to rely not on the symbolic strength of analogies? (shrink)

In preference aggregation a set of individuals express preferences over a set of alternatives, and these preferences have to be aggregated into a collective preference. When preferences are represented as orders, aggregation procedures are called social welfare functions. Classical results in social choice theory state that it is impossible to aggregate the preferences of a set of individuals under different natural sets of axiomatic conditions. We define a first-order language for social welfare functions and we give a complete axiomatisation for (...) this class, without having the number of individuals or alternatives specified in the language. We are able to express classical axiomatic requirements in our first-order language, giving formal axioms for three classical theorems of preference aggregation by Arrow, by Sen, and by Kirman and Sondermann. We explore to what extent such theorems can be formally derived from our axiomatisations, obtaining positive results for Sen’s Theorem and the Kirman-Sondermann Theorem. For the case of Arrow’s Theorem, which does not apply in the case of infinite societies, we have to resort to fixing the number of individuals with an additional axiom. In the long run, we hope that our approach to formalisation can serve as the basis for a fully automated proof of classical and new theorems in social choice theory. (shrink)

We look at extensions (i.e., stronger logics in the same language) of the Belnap–Dunn four-valued logic. We prove the existence of a countable chain of logics that extend the Belnap–Dunn and do not coincide with any of the known extensions (Kleene’s logics, Priest’s logic of paradox). We characterise the reduced algebraic models of these new logics and prove a completeness result for the first and last element of the chain stating that both logics are determined by a single finite logical (...) matrix. We show that the last logic of the chain is not finitely axiomatisable. (shrink)

This is the second of a series of papers that investigate fragments of quasi-Nelson logic (QNL) from an algebraic logic standpoint. QNL, recently introduced as a common generalization of intuitionistic and Nelson’s constructive logic with strong negation, is the axiomatic extension of the substructural logic |$FL_{ew}$| (full Lambek calculus with exchange and weakening) by the Nelson axiom. The algebraic counterpart of QNL (quasi-Nelson algebras) is a class of commutative integral residuated lattices (a.k.a. |$FL_{ew}$|-algebras) that includes both Heyting and Nelson algebras (...) and can be characterized algebraically in several alternative ways. The present paper focuses on the algebraic counterpart (a class we dub quasi-Nelson implication algebras, QNI-algebras) of the implication–negation fragment of QNL, corresponding to the connectives that witness the algebraizability of QNL. We recall the main known results on QNI-algebras and establish a number of new ones. Among these, we show that QNI-algebras form a congruence-distributive variety (Cor. 3.15) that enjoys equationally definable principal congruences and the strong congruence extension property (Prop. 3.16); we also characterize the subdirectly irreducible QNI-algebras in terms of the underlying poset structure (Thm. 4.23). Most of these results are obtained thanks to twist representations for QNI-algebras, which generalize the known ones for Nelson and quasi-Nelson algebras; we further introduce a Hilbert-style calculus that is algebraizable and has the variety of QNI-algebras as its equivalent algebraic semantics. (shrink)