4,842 research outputs found

    The thermodynamic meaning of negative entropy

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    Landauer's erasure principle exposes an intrinsic relation between thermodynamics and information theory: the erasure of information stored in a system, S, requires an amount of work proportional to the entropy of that system. This entropy, H(S|O), depends on the information that a given observer, O, has about S, and the work necessary to erase a system may therefore vary for different observers. Here, we consider a general setting where the information held by the observer may be quantum-mechanical, and show that an amount of work proportional to H(S|O) is still sufficient to erase S. Since the entropy H(S|O) can now become negative, erasing a system can result in a net gain of work (and a corresponding cooling of the environment).Comment: Added clarification on non-cyclic erasure and reversible computation (Appendix E). For a new version of all technical proofs see the Supplementary Information of the journal version (free access

    Herbivorous copepods with emphasis on dynamic Paracalanus quasimodo in an upwelling region

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    A ressurgência transfere a água rica em nutrientes do fundo dos oceanos para a superfície, o que beneficia a produção primária e, consequentemente, aumenta a produção biológica local. Cabo Frio é favorecido pelo fenômeno e os copépodes são um dos grupos mais beneficiados. Os resultados mostraram que Pacalanus quasimodo foi a espécie mais abundante em relação às demais devido sua resposta rápida à floração. Assim, este estudo tem como objetivo avaliar a herbivoria e dinâmica das populações de copépodes, com ênfase em P. quasimodo. Os resultados mostraram que a temperatura influencia a produção primária, que, por sua vez, favorece a biomassa séston (R2 = 0,65, p = 0,008). A dominância de P. quasimodo deveu-se à disponibilidade de alimento (R2 = 0,83) e a elevada densidade da população leva a um decréscimo da diversidade (R2 = 0,63, p = 0,002). Nossos resultados revelaram que a predação por copépodes carnívoros, como Corycaeus spp. e Oncaea spp., é o principal fator que afeta a dominância de P. quasimodo (R2 = 0,70, p = 0,004; βcopépodes predador = 0,41, p = 0,04).Coastal upwelling is known to transfer the nutrient-rich water from the deep ocean to the surface, which benefits primary production and consequently increases local organic production. Cabo Frio is favored by the phenomenon and copepods are one of the groups most benefited. According to the results presented here, the higher abundances of Pacalanus quasimodo relative to other species are due to its rapid response to upwelling-dependent blooms. Therefore this study aims to assess the herbivory and dynamics of many copepod populations with emphasis on P. quasimodo. The results showed that temperature influences primary production, which in turn benefits the seston biomass (R2 = 0.65, p = 0.008). The dominance of P. quasimodo was due to its emphasis on herbivory (R2 = 0.83) and lead to a decrease in the planktonic diversity (R2 = 0.63, p = 0.002). Our results revealed that predation by carnivorous copepods, like Corycaeus spp. and Oncaea spp. is the main opposing factor affecting P. quasimodo dominance. (R2 = 0.70, p = 0.004; βpredators = 0.41, p = 0.04)

    Commonsense Properties from Query Logs and Question Answering Forums

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    Commonsense knowledge about object properties, human behavior and general concepts is crucial for robust AI applications. However, automatic acquisition of this knowledge is challenging because of sparseness and bias in online sources. This paper presents Quasimodo, a methodology and tool suite for distilling commonsense properties from non-standard web sources. We devise novel ways of tapping into search-engine query logs and QA forums, and combining the resulting candidate assertions with statistical cues from encyclopedias, books and image tags in a corroboration step. Unlike prior work on commonsense knowledge bases, Quasimodo focuses on salient properties that are typically associated with certain objects or concepts. Extensive evaluations, including extrinsic use-case studies, show that Quasimodo provides better coverage than state-of-the-art baselines with comparable quality

    Symbolic Quantum Simulation with Quasimodo

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    The simulation of quantum circuits on classical computers is an important problem in quantum computing. Such simulation requires representations of distributions over very large sets of basis vectors, and recent work has used symbolic data-structures such as Binary Decision Diagrams (BDDs) for this purpose. In this tool paper, we present Quasimodo, an extensible, open-source Python library for symbolic simulation of quantum circuits. Quasimodo is specifically designed for easy extensibility to other backends. Quasimodo allows simulations of quantum circuits, checking properties of the outputs of quantum circuits, and debugging quantum circuits. It also allows the user to choose from among several symbolic data-structures -- both unweighted and weighted BDDs, and a recent structure called Context-Free-Language Ordered Binary Decision Diagrams (CFLOBDDs) -- and can be easily extended to support other symbolic data-structures.Comment: 15 pages; 35th International Conference on Computer Aided Verification (CAV 2023

    Modelling Clock Synchronization in the Chess gMAC WSN Protocol

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    We present a detailled timed automata model of the clock synchronization algorithm that is currently being used in a wireless sensor network (WSN) that has been developed by the Dutch company Chess. Using the Uppaal model checker, we establish that in certain cases a static, fully synchronized network may eventually become unsynchronized if the current algorithm is used, even in a setting with infinitesimal clock drifts

    L'AUTRE AU FEMININ DANS LA POESIE DE SALVATORE QUASIMODO

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    International audienceIl s'agit de montrer la place et la fonction de la figure féminine, réelle ou emblématique, dans le corpus poétique de Salvatore Quasimodo. Dans le poème Sulle rive del Lambro (Nuove poesie) le je lyrique s’adresse à une seconde personne, probablement féminine, en lui disant ces mots : « Tu in ascolto sorridi alla tua mente ». Ce vers et ce type d’adresse nous semblent particulièrement représentatifs de la manière dont Quasimodo fait intervenir, dans une bonne quarantaine de ses poèmes (depuis les années 30 jusqu’au dernier recueil), une interlocutrice féminine, représentée tantôt comme une présence tacite qui incarne le mythe, tantôt comme un individu réel issu de la biographie de l’auteur2, ou même les deux à la fois

    String Department Recital, March 29, 1993

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    This is the concert program of the String Department Recital on Monday, March 29, 1993 at 8:00 p.m., at the Marshall Room, 855 Commonwealth Avenue. Works performed were Andante sostenuto from Violin Concerto No. 1 by Aram Khachaturian, Allegro vivace and Adagio affetuoso from Sonata for Cello and Piano in F major, Op. 99 by Johannes Brahms, I and II from Sonata for Viola Solo, Op. 25 No. 1 by Paul Hindemith, Allegro and Adagio from Concerto No. 2 in D major by Karl Ditters von Dittersdorf, Suite for Cello Solo by Gaspar Cassadó, Andante assai and Sllegro brusco from Sonata No. 1 in F minor for Violin and Piano, Op. 80 y Sergey Prokofiev, Adagio and Fuga from Sonata No. 1 in G minor for Violin Solo, BWV 1001 by Johann Sebastian Bach, From "Quasimodo Sunday" by John Felice, Andante and Adagio religioso from Concerto No. 4 in D minor for Violin and Piano, Op. 31 by Henri Vieuxtemps, Élégie by Igor Stravinsky, Allegro and Adagio from Sonata No. 3 for Violin and Piano in D minor, Op. 108 by J. Brahms, and Allegretto from Cello Concerto No. 1, Op. 107 by Dmitri Shostakovich. Digitization for Boston University Concert Programs was supported by the Boston University Humanities Library Endowed Fund
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