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The Seventh Letter: A Discussion of Myles Burnyeat and Michael Frede, The Pseudo-Platonic Seventh Letter
No full textBurnyeat and Frede argue that the seventh of the letters ascribed to Plato is no more genuine than any other letter purporting to be from a philosopher before Epicurus; that its true author is far too remote from Plato for it to give any reliable evidence about Plato’s thoughts and activities; and that it is to be appreciated as a fine tragedy in prose. This review criticizes some of the details of their arguments, while endorsing and amplifying their conclusion
A single dividing cell population with imbalanced fate drives oesophageal tumour growth
No full textUnderstanding the cellular mechanisms of tumour growth is key for designing rational anticancer treatment. Here we used genetic lineage tracing to quantify cell behaviour during neoplastic transformation in a model of oesophageal carcinogenesis. We found that cell behaviour was convergent across premalignant tumours, which contained a single proliferating cell population. The rate of cell division was not significantly different in the lesions and the surrounding epithelium. However, dividing tumour cells had a uniform, small bias in cell fate so that, on average, slightly more dividing than non-dividing daughter cells were generated at each round of cell division. In invasive cancers induced by KrasG12D expression, dividing cell fate became more strongly biased towards producing dividing over non-dividing cells in a subset of clones. These observations argue that agents that restore the balance of cell fate may prove effective in checking tumour growth, whereas those targeting cycling cells may show little selectivity
Differentiation imbalance in single oesophageal progenitor cells causes clonal immortalization and field change
No full textMultiple cancers may arise from within a clonal region of preneoplastic epithelium, a phenomenon termed ‘field change’. However, it is not known how field change develops. Here we investigate this question using lineage tracing to track the behaviour of scattered single oesophageal epithelial progenitor cells expressing a mutation that inhibits the Notch signalling pathway. Notch is frequently subject to inactivating mutation in squamous cancers3–6. Quantitative analysis reveals that cell divisions that produce two differentiated daughters are absent from mutant progenitors. As a result, mutant clones are no longer lost by differentiation and become functionally immortal. Furthermore, mutant cells promote the differentiation of neighbouring wild-type cells, which are then lost from the tissue. These effects lead to clonal expansion, with mutant cells eventually replacing the entire epithelium. Notch inhibition in progenitors carrying p53 stabilizing mutations creates large confluent regions of doubly mutant epithelium. Field change is thus a consequence of imbalanced differentiation in individual progenitor cells
Reseña. Las normas de la naturaleza. Estudios de ética helenística
No full textLas normas de la naturaleza es una obra construida a partir de las contribuciones de importantes académicos dedicados al estudio de la filosofía antigua y moderna dentro del marco de la Tercera Conferencia sobre Filosofía Helenística, realizada en Bad Homburg (Alemania) en el año de 1983.
Dentro de la lista de conferencistas encontramos nombres que ya nos son familiares por pertenecer a quienes, en los últimos tiempos, han hecho los más grandes y valiosos aportes a la investigación de las teorías de Aristóteles, Platón y los filósofos presocráticos, entre otras corrientes del pensamiento antiguo. Julia Annas, Martha Nussbaum, T. H. Irwin, Michael Frede, David Furley —para mencionar sólo algunos— forman parte del selecto grupo reunido esta vez con el propósito de discutir las perspectivas éticas de las tres corrientes principales de la filosofía helenística, a saber: el escepticismo, el estoicismo y el epicureísmo
Reseña. Las normas de la naturaleza. Estudios de ética helenística
No full textLas normas de la naturaleza es una obra construida a partir de las contribuciones de importantes académicos dedicados al estudio de la filosofía antigua y moderna dentro del marco de la Tercera Conferencia sobre Filosofía Helenística, realizada en Bad Homburg (Alemania) en el año de 1983.
Dentro de la lista de conferencistas encontramos nombres que ya nos son familiares por pertenecer a quienes, en los últimos tiempos, han hecho los más grandes y valiosos aportes a la investigación de las teorías de Aristóteles, Platón y los filósofos presocráticos, entre otras corrientes del pensamiento antiguo. Julia Annas, Martha Nussbaum, T. H. Irwin, Michael Frede, David Furley —para mencionar sólo algunos— forman parte del selecto grupo reunido esta vez con el propósito de discutir las perspectivas éticas de las tres corrientes principales de la filosofía helenística, a saber: el escepticismo, el estoicismo y el epicureísmo
Die Rezeption des Buches Lambda der Metaphysik des Aristoteles und dessen Prinzipienlehre
No full textEine belangvolle Transformation ist das zwölfte Buch (Lambda) der „Metaphysik“ des Aristoteles durch verschiedene Interpretationen im Laufe der Jahrhunderte widerfahren, sodass es als eine theologische Schrift bis heute überliefert ist (1. Kapitel). Dabei waren sowohl der ursprüngliche Sinn des Autors als auch die Struktur des Textes kaum erkennbar geworden. Die vorliegende Arbeit ist eine historische Rekonstruktion der verschiedenen Interpretationen des Textes seit den ersten peripatetischen Denkern bis zur Gegenwart, insbesondere die von Michael Frede (2. Kapitel), Lindsay Judson (3. Kapitel) und Stephen Menn (4. Kapitel). Frede behauptet, das Buch Lambda sei eine Untersuchung der Substanz (Ousiologie); Judson denkt, dass es die erste Philosophie vorlegt; Menn argumentiert, es sei eher eine Forschung der ersten Prinzipien (Archäologie). Hier wird eine weitere Meinung vertreten, nämlich, dass Lambda die Untersuchung der Prinzipien der Substanz ist und somit verkörpert es Aristoteles’ Verständnis der Sophia (5. Kapitel). Überdies löst diese neuartige Lesart des Textes das Problem der Stelle des zwölften Buches innerhalb der „Metaphysik“ dank der Abfassung einer Karte, die seine Struktur verdeutlicht (Anhänge).The twelfth book (Lambda) of the “Metaphysics” of Aristotle has undergone a crucial transformation through the diverse interpretations over the centuries. Thus it has been transmitted up to today as a theological writing (chapter 1). But this made hardly recognizable both the original intention of the author and the structure of the text. The present work is a historical reconstruction of the various interpretations of the text since the first Peripatetic thinkers until today, especially those by Michael Frede (chapter 2), Lindsay Judson (chapter 3) and Stephen Menn (chapter 4). Frede states that the book Lambda is an inquiry into the substance (ousiology); Judson thinks that it presents the first philosophy; Menn argues that it is rather an investigation about the first principles (archaeology). A different opinion is set forth here, namely, that the book Lambda explores the principles of the substance, and in doing so it embodies Aristotle’s understanding of the sophia (chapter 5). Moreover, this new reading of the text solves the problem of the position of the twelfth book in the “Metaphysics” thanks to the composition of a map, which clarifies its structure (appendix)
Transformer Current Ringing in Dual Active Bridge Converters
No full textIn dual active bridge (DAB) converters, there can be transformer current ringing, especially when the transformer turns ratio is high. It is induced by high dv/dt generated by fast switching as well as the low impedance of the magnetic tank at the high-frequency range. To quantify the influence of the magnetic tank, its impedance model is thoroughly modeled by considering all the parasitic components. It is found that the parasitic capacitors of the magnetics do not equally affect the current ringing, and thereby the critical one is addressed. On top of that, the design guide of the inductor is provided for the mitigation of the current ringing. Additionally, the impact of dv/dt is also studied. The models and analyses are verified on a 2.5-kW DAB prototype.DC systems, Energy conversion & Storag
A Decentralized Frequency Regulation Scheme in AC Microgrids
No full textMicrogrids (MGs) are becoming active segments of future power systems. Frequency regulation inislanded MGs is of high importance to guarantee stable and reliable operation under different loading conditions. This paper proposes a decentralized frequency regulation of AC MGs, which relies on the local information. Comparing to the conventional approaches, the proposed scheme does not require a communication system for frequency regulation, resulting in higher reliability and lower costs. Simulation results verify the effectiveness of the proposed frequency control strategy.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Intelligent Electrical Power Grid
A Dual Active Bridge Converter with an Extended High-Efficiency Range by DC Blocking Capacitor Voltage Control
No full textA Dual Active Bridge (DAB) converter can achieve a wide high-efficiency range when its input and output voltages are equal, assuming a 1:1 turns ratio for its isolation transformer. If its input or output voltage is doubled, efficiency of the DAB will drop significantly, because of the introduction of hard switching and high circulating power. Thus, a new modulation scheme has been proposed, whose main idea is to introduce a voltage offset across the dc blocking capacitor connected in series with the transformer. Operational principle of the proposed modulation has been introduced, before analyzing its soft-switching area and circulating power mathematically. The final modulation scheme is not difficult to implement, but can help the DAB achieve soft switching, low circulating power, and thereby high efficiency, even with its input or output voltage doubled.These features have been verified by experimental results obtained with a 1.2 kW prototype.Accepted Author ManuscriptDC systems, Energy conversion & Storag
A crítica de David Hume ao ceticismo pirrônico na obra "Investigação sobre o entendimento humano" e a crítica contemporânea ao pirronismo de "Sexto empírico"
No full textOur goal with this work is to develop a exposition of the David Hume’s criticism against the Pyrrhonean Skeptics in the work An Enquiry Concerning Human Understanding, showing that it stands in the light of the contemporary understanding of skepticism outlined by Sextus Empiricus in Book I of Outlines of Pyrrhonism. We will see by what argument Sextus argues, in the side of the pyrrhonist, a life without beliefs. Then, we compare the work of Sextus with, mainly, the debate’s conclusions between Michael Frede e Myles Burnyeat (urbane and rustic interpretations) concern the possibility of the pyrrhonist engage coherently in his Pyrrhonism, t. is, the Pyrrhonean modus vivendi without beliefs, endorsing the Burnyeat’s position about it infeasibility. We will present, furthermore, a virtual bibliography by which Hume could have educated himself concerning Sextus and his Pyrrhonism, objections presented by Julia Annas against the comprehension of Hume about ancient skepticism and, finally, we will ponder the position of some commentators who see in the mitigated skepticism of Hume, first of all, a sort of Pyrrhonism. Armed with this analyzes, to the extent that the core of Hume’s criticism is the total suspension of beliefs by the pyrrhonists, as well as the inescapable human nature grounded in the instinctive mechanism of habit or custom as the generator of beliefs concerning the empirical objects of our reasoning, then, one cannot deny the validity of Hume’s critique.Nosso objetivo com este trabalho é desenvolver uma exposição da crítica que David Hume lança contra os céticos pirrônicos na obra Investigação Sobre o Entendimento Humano, mostrando que se mantém de pé à luz da contemporânea compreensão que se tem do ceticismo esboçado por Sexto Empírico no Livro I das Hipotiposes Pirrônicas. Veremos por qual argumento Sexto defende, ao pirrônico, uma vida sem crenças. Então cotejamos o trabalho de Sexto com, principalmente, as conclusões do debate travado entre Michael Frede e Myles Burnyeat (interpretações urbana e rústica) sobre a possibilidade de o pirrônico ser coerente com seu pirronismo, i. é, o modus vivendi pirrônico sem crenças, endossando a posição de Burnyeat sobre sua inviabilidade. Apresentaremos, ainda, uma bibliografia virtual pela qual Hume poderia ter-se educado sobre Sexto e seu pirronismo, objeções apresentadas por Julia Annas à compreensão de Hume do ceticismo antigo e, finalmente, ponderaremos a posição de alguns comentadores que veem no ceticismo mitigado de Hume, antes de tudo, uma espécie de pirronismo. Munidos dessas análises, na medida em que o cerne da crítica de Hume é a suspensão total das crenças pelos pirrônicos, como assim também a inescapável natureza humana calcada no mecanismo instintivo do hábito ou costume como gerador de crenças relativas aos objetos empíricos de nossos raciocínios, então, não se pode negar a validade da crítica de Hume
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