7,943 research outputs found
A rational approach to Pi, Notes of a lecture held on the occasion of Pi-day on July 5, 2000 in Leiden
No full textThis article is based on notes for the lecture with the same title, which was held by the author on the occasion of the `Pi in de Pieterskerk' event (Pi-day) on July 5, 2000. The present article expands these notes with short proofs of most of the theorems given, but not proved, during the lecture
I giuochi olimpici celebrati dagli Arcadi nell'ingresso dell'Olimpiade DCXXV. in lode della Santità di N.S. papa Innocenzio XII. /
No full textEngraved title vignette (device of the Accademia degli Arcadi); woodcut head- and tail-pieces.Signatures: pi⁴ A-I⁴ K⁶.Mode of access: Internet.Library copy bound with: I giuochi olimpici celebrati dagli Arcadi per i'ingresso dell'Olimpiade DCXXVI. Roma : Antonio de' Rossi, 1726
Controlling Information Release in the pi-calculus
No full textWe introduce a notion of controlled information release for a typed version of the pi-calculus extended with declassification
primitives; this property scales to noninterference when downgrading is not allowed. We provide various characterizations of controlled release, based on a typed behavioural equivalence relative to a security level s, which captures the idea of externalbobservers of level s. First, we define our security property through a universal quantification over all the possible active attackers, i.e., malicious processes which interact with the system possibly leaking secret information. Then we characterize the controlled release property in terms of an unwinding condition, which deals with so-called passive attackers trying to infer confidential information just by observing the behaviour of the system. Furthermore, we express controlled information release in terms of partial equivalence relations (per models, for short) in the style of a stream of similar studies for imperative
and multi-threaded languages. We show that the controlled release property is compositional with respect to most operators of the language leading to efficient proof techniques for the verification and the construction of (compositional) secure systems
P-congruences as noninterference for the pi-calculus.
No full textWe introduce a notion of noninterference for a typed version of the pi-calculus where types are used to assign secrecy levels to channels. Noninterference is expressed in terms of a partial congruence (p-congruence, for short). We provide a proof technique in the form of a bisimulation-like partial equivalence relation that is a binary relation which is symmetric and transitive but not reflexive.
We show that the noninterference property is compositional with respect to most of the operators of the language leading to efficient proof techniques for the verification and the construction of (compositional) secure systems.
In order to allow downgrading of sensitive information, we extend the pi-calculus with declassification primitives and we study a property which scales to noninterference when downgrading is not permitted
"I' ll tell you a story that will make you believe" in narratives: the role of metafiction in the novel and in the film Life of Pi
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Inglês: Estudos Linguísticos e Literários, Florianópolis, 2015.Recentes estudos propõem que adaptações cinematográficas sejam entendidas como fonte de criação, os quais refletem contextos e interpretações diferentes do texto em que são baseadas. Nessa dissertação, propõe-se uma análise comparativa do romance Life of Pi (2001), de Yann Martel e do filme homônimo dirigido por Ang Lee (2012). A análise tem como objetivo identificar a presença e o modo em que a metaficção é construída no romance e no filme, e quais são alguns significados produzidos por ela em ambos os textos, tanto o literário quanto o fílmico. A concepção de metafição se baseia nas definições de Linda Hutcheon e Patricia Waugh. Por metaficção, entende-se a ficção consciente de si, que expõe o processo de escrita ao leitor e o convida a ter um papel ativo na construção do significado. Após uma análise comparativa dos dois textos, conclui-se que a metaficção está presente em ambos, tanto tematicamente como estruturalmente. As reflexões sobre narrativas apresentadas pelos personagens, o uso de vários níveis narrativos e de intertextualidade revelam diferentes usos da metafição em ambos. A diferença mais importante entre o romance e o filme Life of Pi está no uso dos níveis narrativos. Enquanto o romance possui um ?autor? sem nome que apresenta a história aos leitores, o filme possui um diretor implícito que deixa pistas de qual versão da história de Pi é ?real? no contexto da narrativa. Essa diferença dá ao romance um final aberto, em que o leitor deve escolher qual versão da história ele acredita, enquanto o filme possui uma resolução para essa questão. O filme, então, pode ser entendido como um testemunho, uma narrativa de trauma de um sobrevivente de um naufrágio e da experiência de migração, enquanto o livro não apresenta uma decisão em relação às versões da história, deixando o leitor aberto a qualquer possibilidade.Abstract : Recent studies propose that Film Adaptations should be understood as sources of creation, which also reflect a different context and interpretation from the text upon which they were based. In this thesis, I propose a comparative analysis of the novel Life of Pi (2001), by Yann Martel, and the homonymous film directed by Ang Lee (2012). The analysis has the objective of identifying the presence and the way in which metafiction is constructed in the novel and in the film, and what are some of the meanings produced by it in both texts, the filmic and the literary. The concept of metafiction was based on the definitions by Linda Hutcheon and Patricia Waugh. It is understood as the self-conscious fictional text, which exposes the writing process to the readers and invites them to have an active role in the construction of meaning. In the comparative analyses of the two texts, I have proved that metafiction is present in the two texts, both thematically and structurally. The reflections of the characters on narrative itself as well as the use of different narrative levels and intertextual references reveal different uses of metanarrative in both film and novel. The most important difference between the novel and the film Life of Pi is in their uses of different narrative levels. While the novel has an unnamed =author? who presents the story to the readers, the film has an implicit director who leaves =clues? of which version of Pi?s story is ?real? in the context of the narrative. This difference gives to the novel an open end, facein which the readers must choose which version of the story they believe in, while the film presents a resolution to this question. The film, thus, can be understood as a testimony narrative, a narrative of the trauma of a survivor from a shipwreck and from the experience of migration, while the novel does not decide for one of the versions of the story, enabling a more inconclusive reading
Malonate Crown Ethers as Building Blocks for Novel D-pi-A Chromophores
No full textA series of new crown ethers, Incorporating a malonate ester functionality, have been synthesized and derivatized with pi-electron rich aldehydes; to give, conjugated, extended "push-pull" compounds. Their ability to bind Lewis acid-like metal cations, such as Mg2+ and Eu3+, has been characterized, and the relative stability constants are presented. When the metal cation is bound to the malonate moiety within the crown ether cavity, the D-pi-A character of the molecular structure is greatly enhanced
Aromatic Polyphenol π-π Interactions with Superoxide Radicals Contribute to Radical Scavenging and Can Make Polyphenols Mimic Superoxide Dismutase Activity
No full textPolyphenols are valuable natural antioxidants present in our diet that likely mitigate aging effects, neurodegenerative conditions, and other diseases. However, because of their poor absorption in the gut and consequent low concentration in biological fluids (µM range), reservations about polyphenol antioxidant efficiency have been raised. In this review, it is shown that after scavenging superoxide radicals, coumarin, chalcone, and flavonoid polyphenols can reform themselves, becoming ready for additional cycles of scavenging, similar to the catalytic cycle in superoxide dismutase (SOD) action. The π-π interaction between one polyphenol ring and superoxide is associated with oxidation of the latter due to transfer of its unpaired electron to a polyphenolic aromatic ring, and consequent formation of a molecule of O2 (one product of SOD action). Mechanistically, it is very difficult to establish if this π-π interaction proceeds before or after the most common mode of scavenging superoxide, e.g., abstraction of an aromatic polyphenol H(hydroxyl), which then is used to form H2O2 (the other molecule produced by SOD action). At the end of this cycle of superoxide scavenging, 4-methyl-7,8-di-hydroxy-coumarin and the flavonoid galangin reform themselves. An alternative mechanistic pathway by galangin forms the η-(H2O2)-galangin-η-O2 complex that includes additional H2O2 and O2 molecules. Another mode of action is seen with the chalcone butein, in which the polyphenol system incorporates a molecule of O2, e.g., a η-O2-butein complex is formed, ready for additional scavenging. Of the several families of polyphenols analyzed in this review, only butein was able to circumvent an initial π-π interaction, directing the superoxide towards H(hydroxyl) in position 4, e.g., acting as a typical polyphenol scavenger of superoxide. This fact did not impede an additional superoxide to later react with the aromatic ring in π-π fashion. It is concluded that by mimicking SOD enzyme action, the low concentration of polyphenols in biological fluids is not a limiting factor for effective scavenging of superoxide
PicNic - Pi-calculus Non-Interference checker
No full textPICNIC is a tool for verifying security properties of systems, namely non-interference properties of processes expressed as terms of the pi-calculus with two security levels and declassification primitives. More precisely, it checks whether inserting a process into two different high contexts no information leakage to the low level observers occurs. These properties are decidable over finite control processes, but decidability can be extended by compositionality also to some infinite state processes. Notably, PICNIC has been developed in Fresh OpsilaCaML, a dialect of CaML with native support for binders and fresh/local names; thus, this work can be seen also as a non-trivial case study about the applicability of these new programming languages
Tangle-bearing neurons survive despite disruption of membrane integrity in a mouse model of tauopathy
No full textNeurofibrillary tangles (NFTs) are associated with neuronal loss and correlate with cognitive impairment in Alzheimer disease, but how NFTs relate to neuronal death is not clear. We studied cell death in Tg4510 mice that reversibly express P301L mutant human tau and accumulate NFTs using in vivo multiphoton imaging of neurofibrillary pathology, propidium iodide (PI) incorporation into cells, caspase activation, and DNA labeling. We first observed that in live mice, a minority of neurons were labeled with the caspase probe or with PI fluorescence. These markers of cell stress were localized in the same cells and appeared specifically within NFT-bearing neurons. Contrary to expectations, the PI-stained neurons did not die during a day of observation; the presence of Hoechst-positive nuclei in them on the subsequent day indicated that the NFT-associated membrane disruption, as suggested by PI staining, and caspase activation do not lead to immediate death of neurons in this tauopathy model. This unique combination of in vivo multiphoton imaging with markers of cell death and pathological alteration is a powerful tool for investigating neuronal damage associated with neurofibrillary pathology
Amplitude analysis of D-0 -> K- pi(+) pi(+) pi(-)
No full textKolcu, Onur Buğra (Arel Author)Kolcu, Onur Buğra (Arel Author)We present an amplitude analysis of the decay D-0 -> K- pi(+)pi(+)pi(-) based on a data sample of 2.93 fb(-1) acquired by the BESIII detector at the psi(3770) resonance. With a nearly background free sample of about 16000 events, we investigate the substructure of the decay and determine the relative fractions and the phases among the different intermediate processes. Our amplitude model includes the two-body decays D-0 -> (K) over bar*(0)rho(0), D-0 -> K- a(1)(+) (1260) and D-0 -> K-1(-)(1270)pi(+), the three-body decays D-0 -> K-1(-)*(0)pi(+)pi(-) and D-0 -> K- pi(+)rho(0), as well as the four-body nonresonant decay D-0 -> K- pi(+)pi(+)pi(-). The dominant intermediate process is D-0 -> K(-)a(1)(+)(1260)accounting for a fit fraction of 54.6%.We present an amplitude analysis of the decay D-0 -> K- pi(+)pi(+)pi(-) based on a data sample of 2.93 fb(-1) acquired by the BESIII detector at the psi(3770) resonance. With a nearly background free sample of about 16000 events, we investigate the substructure of the decay and determine the relative fractions and the phases among the different intermediate processes. Our amplitude model includes the two-body decays D-0 -> (K) over bar*(0)rho(0), D-0 -> K- a(1)(+) (1260) and D-0 -> K-1(-)(1270)pi(+), the three-body decays D-0 -> K-1(-)*(0)pi(+)pi(-) and D-0 -> K- pi(+)rho(0), as well as the four-body nonresonant decay D-0 -> K- pi(+)pi(+)pi(-). The dominant intermediate process is D-0 -> K(-)a(1)(+)(1260)accounting for a fit fraction of 54.6%
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