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John D. Norton is responsible for a number of influential views in contemporary philosophy of science. This paper will discuss two of them. The material theory of induction claims that inductive arguments are ultimately justified by their material features, not their formal features. Thus, while a deductive argument can be valid irrespective of the content of the propositions that make up the argument, an inductive argument about, say, apples, will be justified (or not) depending on facts about apples. The argument view of thought experiments claims that thought experiments are arguments, and that they function epistemically however arguments do. These two views have generated a great deal of discussion, although there hasn't been much written about their combination. I argue that despite some interesting harmonies, there is a serious tension between them. I consider several options for easing this tension, before suggesting a set of changes to the argument view that I take to be consistent with Norton's fundamental philosophical commitments, and which retain what seems intuitively correct about the argument view. These changes require that we move away from a unitary epistemology of thought experiments and towards a more pluralist position. 相似文献
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The effect of aging treatment on microstructure and mechanical properties of equal channel angular pressed Al-7075 alloy was examined.Commercial Al-7075 alloy in the solid solution heat-treated condition was processed by equal channel angular pressing through route BCat both the room temperature and 120 1C. Only three passes of equal channel angular pressing was possible due to the low ductility of the alloy at both temperatures. Followed by equal channel angular pressing, the specimens have been aged at 120 1C for different aging times. Mechanical properties were measured by Vickers microhardness and tensile tests and microstructural observations were undertaken using transmission electron microscopy, X-ray diffractometer as well as optical microscopy. Microstructural investigations showed that ultrafine-grained materials with grain size in the range of 200–350 nm and 300–500 nm could be obtained after three passes of equal channel angular pressing at room temperature and 120 1C, respectively. Equal channel angular pressing of solid solution heat-treated Al-7075 alloy accelerates precipitation rate and subsequently leads to a significant decrease in aging time to attain maximum mechanical properties. Furthermore, it is possible to achieve maximum mechanical properties during equal channel angular pressing at 120 1C as a result of dynamic aging and formation of small η′ phase. 相似文献
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I claim that one way thought experiments contribute to scientific progress is by increasing scientific understanding. Understanding does not have a currently accepted characterization in the philosophical literature, but I argue that we already have ways to test for it. For instance, current pedagogical practice often requires that students demonstrate being in either or both of the following two states: 1) Having grasped the meaning of some relevant theory, concept, law or model, 2) Being able to apply that theory, concept, law or model fruitfully to new instances. Three thought experiments are presented which have been important historically in helping us pass these tests, and two others that cause us to fail. Then I use this operationalization of understanding to clarify the relationships between scientific thought experiments, the understanding they produce, and the progress they enable. I conclude that while no specific instance of understanding (thus conceived) is necessary for scientific progress, understanding in general is. 相似文献
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T. Covarrubias-Camarillo M. Osorio-Beristain L. Legal 《Journal of Natural History》2016,50(35-36):2299-2310
In at least 18 Lepidoptera families, caterpillars build shelters that mainly serve to regulate microclimate (humidity, temperature) and/or to avoid predation. We aimed to explore the function of the tubular structures built with the leaves of the host plant, Acacia cochliacantha Humboldt and Bonpland ex Willdenow (Fabaceae), by a lepidopteran endemic to Mexico, Baronia brevicornis Salvin. We experimentally evaluated whether tubular structure building behaviour is induced by high temperature or predator odour, and if shelters reduce or enhance predation of B. brevicornis caterpillars. We used Calosoma angulatum as predator. Our analyses showed that caterpillars did not make the tubular structures in response to high temperature. We also found no difference in predators’ visual recognition of sheltered versus unsheltered caterpillars. Caterpillars did not build shelters but they moved more often when exposed to predator odour. Unsheltered caterpillars were more frequently consumed when predators were allowed to interact with sheltered and unsheltered caterpillars. Hence, the tubular structures built by B. brevicornis are most likely a strategy for reducing predation, for example by C. angulatum. 相似文献
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D. J. Wildish S. R. Smith T. Loeza-Quintana A. E. Radulovici S. J. Adamowicz 《Journal of Natural History》2016,50(29-30):1911-1933
Five taxa of talitrid amphipods were found in the archipelago of Bermuda, of which three were recorded there for the first time. Four of these are supralittoral wrack generalists: Platorchestia monodi BOLD:AAB3402, (a unique Molecular Operational Taxonomic Unit according to the Barcode Index Number system), a related species recognized by molecular methods, Platorchestia platensis BOLD:AAA2949, Mexorchestia carpenteri carpenteri BOLD:AAC1491 and Tethorchestia antillensis; and one a terrestrial leaf-litter generalist: Talitroides alluaudi. A key is provided to discriminate between the formally described talitrids of Bermuda. Dispersal mechanisms from the American continent to Bermuda were considered for all taxa based on species distributions along the North American Atlantic coast and also investigated by molecular methods, using genetic population differentiation and haplotype network analysis based on the barcode region of cytochrome c oxidase subunit I gene. For P. monodi BOLD:AAB3402 the genetic results suggest that some dispersal events occurred before human colonization of Bermuda but are equivocal about the source population and therefore the direction of dispersal. Some very recent synanthropic dispersal is possible with this species. For the other two species studied genetically, P. platensis BOLD:AAA2949 and M. c. carpenteri BOLD:AAC1491, the small population samples analysed support dispersal to Bermuda from the American mainland, before human occupation of Bermuda, although the available sample size was limited for these species. The available limited direct, non-genetic evidence supports synanthropic transport for Talitroides alluaudi. Platorchestia monodi BOLD:AAB3402 is found in the same wrack habitat as P. platensis BOLD:AAA2949 on Bermuda, apparently without interbreeding. No evidence was found that driftwood specialist talitrids had become established in Bermuda. 相似文献
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Géza Tamás Szabó Bettina Tarr Krisztina Pálóczi Katalin Éder Eszter Lajkó Ágnes Kittel Sára Tóth Bence György Mária Pásztói Andrea Németh Xabier Osteikoetxea Éva Pállinger András Falus Katalin Szabó-Taylor Edit Irén Buzás 《Cellular and molecular life sciences : CMLS》2014,71(20):4055-4067
Under physiological and pathological conditions, extracellular vesicles (EVs) are present in the extracellular compartment simultaneously with soluble mediators. We hypothesized that cytokine effects may be modulated by EVs, the recently recognized conveyors of intercellular messages. In order to test this hypothesis, human monocyte cells were incubated with CCRF acute lymphoblastic leukemia cell line-derived EVs with or without the addition of recombinant human TNF, and global gene expression changes were analyzed. EVs alone regulated the expression of numerous genes related to inflammation and signaling. In combination, the effects of EVs and TNF were additive, antagonistic, or independent. The differential effects of EVs and TNF or their simultaneous presence were also validated by Taqman assays and ELISA, and by testing different populations of purified EVs. In the case of the paramount chemokine IL-8, we were able to demonstrate a synergistic upregulation by purified EVs and TNF. Our data suggest that neglecting the modulating role of EVs on the effects of soluble mediators may skew experimental results. On the other hand, considering the combined effects of cytokines and EVs may prove therapeutically useful by targeting both compartments at the same time. 相似文献