711 research outputs found
Should surgical training include involvement in a clinical trial?
No full textThe next generation of surgical consultants will need research experience to advance the specialty, writes Dion Morton , but Colin Bicknell worries about increasing the time trainees spend away from the operating theatre, where they learn their craf
Editorial Announcement
No full textIt is an Editorial Announcemente related to the Pan European Coloproctology Trials Portfolio Map of European Society of Coloproctology
Het Cap Set-probleem
No full textMei vorig jaar zorgde de Nederlandse wiskundige Dion Gijswijt van de TU Delft samen met Jordan Ellenberg (University of Wisconsin) voor een doorbraak in het Cap Set-probleem. In dit artikel bespreken Aart Blokhuis en Dion Gijswijt het probleem en de gevonden oplossing aan de hand van het kaartspel SETDiscrete Mathematics and Optimizatio
Formamidinium-Based Dion-Jacobson Layered Hybrid Perovskites: Structural Complexity and Optoelectronic Properties
No full textLayered hybrid perovskites have emerged as a promising alternative to stabilizing hybrid organic–inorganic perovskite materials, which are predominantly based on Ruddlesden-Popper structures. Formamidinium (FA)-based Dion-Jacobson perovskite analogs are developed that feature bifunctional organic spacers separating the hybrid perovskite slabs by introducing 1,4-phenylenedimethanammonium (PDMA) organic moieties. While these materials demonstrate competitive performances as compared to other FA-based low-dimensional perovskite solar cells, the underlying mechanisms for this behavior remain elusive. Here, the structural complexity and optoelectronic properties of materials featuring (PDMA)FAn–1PbnI3n+1 (n = 1–3) formulations are unraveled using a combination of techniques, including X-ray scattering measurements in conjunction with molecular dynamics simulations and density functional theory calculations. While theoretical calculations suggest that layered Dion-Jacobson perovskite structures are more prominent with the increasing number of inorganic layers (n), this is accompanied with an increase in formation energies that render n > 2 compositions difficult to obtain, in accordance with the experimental evidence. Moreover, the underlying intermolecular interactions and their templating effects on the Dion-Jacobson structure are elucidated, defining the optoelectronic properties. Consequently, despite the challenge to obtain phase-pure n > 1 compositions, time-resolved microwave conductivity measurements reveal high photoconductivities and long charge carrier lifetimes. This comprehensive analysis thereby reveals critical features for advancing layered hybrid perovskite optoelectronics.</p
La géographie dans l’Histoire romaine de Cassius Dion
No full textInternational audienceThe work of Cassius Dion is a work of History which begins with the foundation of Rome and ends in the contemporary time of the author (Severus Alexander). It is thus natural that the latter placed, at the heart of his analysis, the imperial space whose expansion is a key factor of the political and institutional mutations. The article shows what Dion retained from the geographical models, how he associated reflection on space and reflection on politics in order to develop a cartography of the Empire: the description has nothing to do anymore with the periegetic circuit since it places the extention of the chôra of the origins at the core of the political and spatial analysis; the natural spaces and the fortified sites are favored, and the author is sensitive to scientific advances allowed by the process of conquest not without showing himself very critical towards it.L’oeuvre de Cassius Dion est une oeuvre d’histoire qui commence à la fondation de Rome et s’achève à l’époque contemporaine de l’auteur, sous Sévère Alexandre. Il est donc naturel que celui-ci ait placé au coeur de son analyse l’espace impérial dont l’expansion est un facteur clef des mutations politiques et institutionnelles. L’article se propose d’examiner ce que Dion a retenu des modèles géographiques, comment il a associé réflexion sur l’espace et réflexion sur le politique pour élaborer une cartographie de l’Empire : le descriptif n’a plus rien du circuit périégétique puisqu’il place l’extension de la chôra des origines au coeur de l’analyse politique et spatiale ; les espaces naturels et les sites fortifiés y sont privilégiés, et l’auteur est sensible aux avancées scientifiques permises par le processus de conquête, non sans se montrer très critique vis-à-vis de celui-ci
An Unlimited Memeiosis of The Godfather: Diachronic and Synchronic Observations of a Pervasive and Ubiquitous Meme
No full textThis chapter is informed by its author’s intent to offer and demonstrate a novel semio-memetic model for the interpretation of Italian signs in the periphery using Francis Ford Coppola’s The Godfather (1972) as a prime example. After discussing ‘The Godfather meme’ this chapter moves beyond the constraints of the materiality of the original cultural artifact (where it originated, i.e., the Puzo text), suggesting that it has now surpassed the original idea and intent of the novel, evolved into a film trilogy, and reached its apotheosis via popular culture, where there is now a plethora of multimodal variations indexed to it. While it is true that The Godfather was and is an Italian American-based text, it has now achieved global multimodality going beyond its original ethnic connection to Italian and Italian American themes. The author concludes by stating that this text has achieved an influence usually reserved for religious and other canonical texts
Using the slice rank for finding upper bounds on the size of cap sets
No full textThe cap set problem consists of finding the maximum size cap sets, i.e. sets without a 3-term arithmetic progression in F₃. In this thesis several known results on the behavior of this number as n → ∞ are presented. In particular we discuss a reformulation by Terence Tao and Will Sawin of a proof found by Dion Gijswijt and Jordan Ellenberg. It uses the slice rank, a rank that is defined for elements of tensor products, to give upper bounds on the size of the cap sets. In this report we will explain the slice rank and how it is related to the size of cap sets. We will also explore whether the slice rank might be used for bounding the size of arithmetic progression-free sets in F_q for q ≠ 3. We show that we can not use the slice rank to give a non-trivial upper bound on the size of n-term progression-free sets for n ≥ 7. This was already known for n ≥ 8
The ethico-politics of writing in Plutarch's <i>Life of Dion</i>
No full textAbstractThe paper focuses on the representation of pedagogical and political communication between (and around) Plato, Dion and Dionysius II in Plutarch's Life of Dion. Plutarch's narrative invokes both the Platonic critique of writing as an inadequate medium for teaching philosophy, and the polarity between free oral speech and writing as a symptom of tyranny. It is argued that the Life espouses but also complicates and implicitly interrogates the opposition between writtenness and orality across the philosophical and the political domain, thus constituting a rich intertextual response, from an Imperial Platonist author, to the Platonic concerns about the written word.</jats:p
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