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1.
The life and career of Lorenz Spengler (1720–1807) provides evidence to support the view that the eighteenth century was a period when there was a fruitful interrelationship between the arts, crafts, and sciences in the courts and capitals of Europe. Spengler was trained as a turner, and was appointed teacher of ornamental turning to the Danish royal family and turner of the court in 1745. Even in the early years of his artistic career Spengler was interested in electricity and its role in healing, and he became an avid collector of shells and naturalia. Over the years, Spengler's interests turned more to the natural sciences, and in 1771 he was appointed director of the King's Kunstkammer. Only by considering both aspects of Spengler's career can his scientific activities be placed in their proper historical context.  相似文献   

2.
Some time in the late 1590s, the Welsh amateur mathematician John Bulkeley wrote to Thomas Harriot asking his opinion about the properties of a truly gargantuan (but totally imaginary) plano-spherical convex lens, 48 feet in diameter. While Bulkeley’s original letter is lost, Harriot devoted several pages to the optical properties of “Mr Bulkeley his Glasse” in his optical papers (now in British Library MS Add. 6789), paying particular attention to the place of its burning point. Harriot’s calculational methods in these papers are almost unique in Harriot’s optical remains, in that he uses both the sine law of refraction and interpolation from Witelo’s refraction tables in order to analyze the passage of light through the glass. For this and other reasons, it is very likely that Harriot wrote his papers on Bulkeley’s glass very shortly after his discovery of the law and while still working closely with Witelo’s great Optics; the papers represent, perhaps, his very first application of the law. His and Bulkeley’s interest in this giant glass conform to a long English tradition of curiosity about the optical and burning properties of large glasses, which grew more intense in late sixteenth-century England. In particular, Thomas Digges’s bold and widely known assertions about his father’s glasses that could see things several miles distant and could burn objects a half-mile or further away may have attracted Harriot and Bulkeley’s skeptical attention; for Harriot’s analysis of the burning distance and the intensity of Bulkeley’s fantastic lens, it shows that Digges’s claims could never have been true about any real lens (and this, I propose, was what Bulkeley had asked about in his original letter to Harriot). There was also a deeper, mathematical relevance to the problem that may have caught Harriot’s attention. His most recent source on refraction—Giambattista della Porta’s De refractione of 1593—identified a mathematical flaw in Witelo’s cursory suggestion about the optics of a lens (the only place that lenses appear, however fleetingly, in the writings of the thirteenth-century Perspectivist authors). In his early notes on optics, in a copy of Witelo’s optics, Harriot highlighted Witelo’s remarks on the lens and della Porta’s criticism (which he found unsatisfactory). The most significant problem with Witelo’s theorem would disappear as the radius of curvature of the lens approached infinity. Bulkeley’s gigantic glass, then, may have provided Harriot an opportunity to test out Witelo’s claims about a plano-spherical glass, at a time when he was still intensely concerned with the problems and methods of the Perspectivist school.  相似文献   

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4.
This article responds to Professor Andrew Janiak's recent attempt to defend the proposition that Isaac Newton did not believe in action at a distance between bodies (or any other kind of substance) (Janiak, 2013). His argument rests on a distinction between “three concepts of causation in Newton”, which leads him to conclude that although Newton did not believe in action at a distance between bodies, he was able to accept that gravity was a “distant action”. I critically examine Janiak's arguments here, and the historical evidence he brings to bear upon it, and argue that Professor Janiak's latest claims do nothing to undermine the view to which he is opposed, namely, that Newton did believe in the possibility of action at a distance between bodies.  相似文献   

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6.
In 1865, Spanish Jesuits founded the Manila Observatory, the earliest of the Far East centres devoted to typhoon and earthquake studies. Also on Philippine soil and under the direction of the Jesuits, in 1884 the Madrid government inaugurated the first Meteorological Service in the Spanish Kingdom, and most probably in the Far East. Nevertheless, these achievements not only went practically unnoticed in the historiography of science, but neither does the process of geophysical dissemination that unfolded fit in with the two types of transmitter of knowledge identified by historians in the missionary diffusion of the exact sciences in colonial contexts. Rather than regarding science as merely a stimulus to their functionary and missionary tasks, Spanish Jesuits used their overseas posting to produce and publish original research –– a feature that would place them within the typology of the ‘seeker’ rather than the ‘functionary’ (in stark contrast to what the standard typology sustains). This paper also analyses examples of synergies between science, education and trade, which denotes, inter alia, the existence of a broad and solid educational structure in the Manila Mission that sustained the strength of research enterprise.  相似文献   

7.
After Galileo’s argument for the autonomy of science is analysed and adapted to take into account later developments of scientific practices, we conclude that, in the final analysis, it is not compelling. Nevertheless, Galileo’s argument still provides a useful point of reference, for aspects of it can be interpreted to anticipate central components of the often acclaimed ideal of science as value free, so that appraising it contributes to the larger purpose of exploring how well that ideal stands up today. Finally, we will argue that residue from Galileo’s struggle with the Church remains with us, making it difficult to identify the conditions that would need to be put into place today for any robust sense of the autonomy of science to be defensible.  相似文献   

8.
Maxwell’s writings exhibit an enduring preoccupation with the role of metaphysics in the advancement of science, especially the progress of physics. I examine the question of the distinction and the proper relation between physics and metaphysics and the way in which the question relies on key notions that bring together much of Maxwell’s natural philosophy, theoretical and experimental. Previous discussions of his attention to metaphysics have been confined to specific issues and polemics such as conceptions of matter and the problem of free will. I suggest a unifying pattern based on a generalized philosophical perspective and varying expressions, although never a systematic or articulated philosophical doctrine, but at least a theme of action and active powers, natural and human, intellectual and material, with sources and grounds in theology, moral philosophy and historical argument. While science was developing in the direction of professional specialization and alongside the rise of materialism, Maxwell held on to conservative intellectual outlook, but one that included a rich scientific life and held science as part of a rich intellectual, cultural and material life. His philosophical outlook integrated his science with and captured the new Victorian culture of construction and work, political, economic, artistic and engineering.  相似文献   

9.
The pseudo-Aristotelian Mechanical Problems is the earliest known ancient Greek text on mechanics, principally concerned with the explanation of a variety of mechanical phenomena using a particular construal of the principle of the lever. In the introduction, the author—thought to be an early Peripatetic—quotes the tragic poet Antiphon to summarise a discussion of the technē-physis (art-nature) relationship and the status of mechanics as a technē. I argue that this citation of a poet is an Aristotelian cultural signature, intended to guide its readers towards a better understanding of the nature of mechanics as expounded in the Mechanical Problems. By analysing several instances where Aristotle cites Antiphon (as well as other tragic poets) in the Aristotelian corpus, I propose that both the author of the Mechanical Problems and Aristotle use poets for the purpose of persuasion. This is in turn explained by understanding the homologous relationship between mechanics-as-technē (according to the author of the Mechanical Problems) and poetics-as-technē (according to Aristotle) in terms of their shared status as poiētikē technē (productive art) and claims to universal knowledge. A final facet of the proposed relationship between mechanics and poetry is hypothesised on the grounds of their mimetic nature.  相似文献   

10.
An account is given of early geological researches in the Malverns, the Church Stretton area, and the Wrekin. The reconnaissance work of Murchison suggested that each of these areas had Silurian sediments, intruded by igneous rocks (called trap or syenite). The early Survey maps were compiled on this theoretical basis, with the result that the Silurian sediments were regarded as the oldest rocks in Shropshire and the Malverns. Local geologists, working in the three areas, and with sufficient time to study the exposures in detail, began to develop the idea of ‘islands’ of Precambrian (Archaean) rock (perhaps showing some stratification), having younger sediments deposited thereon. This Archaean model was taken up and actively developed, and the stratigraphical details worked out, with the island model being gradually modified. Debates were stronger between members of the ‘Archaean’ fraternity than with the Survey. Traces of trilobite remains were found by Callaway at Comley, near Caer Caradoc, and were identified by Lapworth as Olenellus, enabling the underlying Wrekin Quartzite to be established as the base of the Cambrian, in agreement with ideas developed in North America and Scandinavia. Arguments are detailed concerning the relative ages of the ‘Uriconian’ and ‘Longmyndian’ rocks, and their constituent units. Both were agreed to be Precambrian, but the evidence in terms of field mapping, in relation to the Wrekin Quartzite, is not complete. The problems of stratigraphical work in unfossiliferous rocks are displayed, and also the efforts to achieve correlations with areas such as Pembrokeshire and Anglesey are described. Though consensus has been reached on the Precambrian status of the Malvernian, Uriconian and Longmyndian rocks, radiometric age determinations and other evidence throw doubt on some aspects of the consensus, and research continues.  相似文献   

11.
Although there is widespread agreement that many cancers have environmental causes we are often unable to see associations between specific cancers and exposure to environmental chemicals. One might also speulate that the more widespread, common-place and normal a chemical exposure is perceived to be then the less likely it will be that the exposure is recognised, let alone be considered to cause cancer. Widespread contamination of air by chemicals associated with internal combustion may be an example of one such invisible carcinogenic exposure. Yet evidence is available which suggests that many leukaemia and lymphoma cases, as well as other cancers, may be caused by this mundane and ubiquitous environmental contamination. The hypothesis is developed that leukaemia clustering as well as national leukaemia incidence may be related to non-occupational exposure to benzene formed by petrol combustion and resulting from petrol evaporation1. The possible association between exposure to fuel vapours, internal combustion products and cancer merits much closer examination than it receives at present.  相似文献   

12.
Vascular endothelial growth factors (VEGFs), initially thought to act specifically on the vascular system, exert trophic effects on neural cells during development and adulthood. Therefore, the VEGF system serves as a promising therapeutic target for brain pathologies, but its simultaneous action on vascular cells paves the way for harmful side effects. To circumvent these deleterious effects, many studies have aimed to clarify whether VEGFs directly affect neural cells or if the effects are mediated secondarily via other cell types, like vascular cells. A great number of reports have shown the expression and function of VEGF receptors (VEGFRs), mainly VEGFR-1 and -2, in neural cells, where VEGFR-2 has been described as the major mediator of VEGF-A signals. This review aims to summarize and compare the divergent roles of VEGFR-1 and -2 during CNS development and homeostasis.  相似文献   

13.
The main theoretical issues in the study of the history of the Archaean Controversy in Britain, which arose in the first three papers of the present series, are summarized and discussed—in particular the problem of stratigraphical work in rocks where no fossils can be discerned. The ‘Archaean’ geologists showed some leanings towards Neo-Neptunism and this, together with the fact that their work challenged the Murchison/Survey view of British geology, was one of the reasons for the controversy. At a deeper level, however, the question concerned the doctrine of uniformitarianism: Were metamorphic rocks to be found at any part of the stratigraphical column, or were they confined to the earliest period of the Earth's history? The establishment of the concept of Precambrian rocks and a suitable stratotype boundary is essentially a social question that has to be determined within the geological community. Some of the social processes whereby these matters are decided internationally are considered, and it is noted that the best location of the ‘Golden Spike’ for the Precambrian/Cambrian boundary has only just been settled (by vote). The paper also explores some nineteenth-century ideas about the nature of metamorphism, and the early conditions of the world.  相似文献   

14.
Riassunto Esperienze condotte in ratti e topi parabionti hanno permesso di stabilire che il 3-ciclopentil etere del 17-etinilestradiolo, estrogeno dotato di elevatissima attività uterotrofica per via orale, è parimenti fornito di forte potere inibente sulla secrezione gonadotropa ipofisaria. Pure a dosi minime esso rivela chiare proprietà anticoncezionali nei ratti femmine. Sia come inibitore ipofisario che come inibitore della fertilità, tale composto si dimostra notevolmente più attivo del 3-metil etere del 17-etinilestradiolo.  相似文献   

15.
A detailed account is given of the development of the Archaean Controversy in Caernarvonshire and Anglesey. Sedgwick had found no base for his Cambrian in North Wales, but had intimated that some of the unfossiliferous rocks of the Lleyn Peninsula and Anglesey might be older than his Cambrian. He also described two ‘ribs’ of igneous rock: one running from Caernarvon to Bangor; the other inland, parallel to the first and crossing the Llanberis Pass at Llyn Padarn. The early Surveyors (especially Ramsay) supposed that these ‘ribs’ had altered the surrounding rocks, and the resulting ‘Altered Cambrian’ could be traced across the Menai Strait to Anglesey, where it formed the various metamorphic rocks of that island. This view (which thus denied the occurrence of Precambrian on Anglesey) was challenged by the usual coalition of ‘amateurs’ (Hicks, Hughes, Bonney, Callaway, Blake, etc.) with attempts being made to recognize a sequence of Archaean rocks in North Wales similar to that in Pembrokeshire. However, vigorous debate occurred amongst the ‘Archaean’ geologists themselves, especially about a rock at Twt Hill, Caernarvon, and about a claimed unconformity at the base of the Cambrian in the Llanberis Pass, perhaps adjacent to the Llyn Padarn ‘rib’. (This was at first regarded as a Precambrian ‘island’ like those claimed at St David's, the Malverns, etc.) Vigorous debate took place about the location of the claimed Llanberis unconformity, but the ‘Archaeans’ were united in regarding the metamorphic rocks of Anglesey as Precambrian (or Archaean). Eventually, the greywackes of Anglesey, and around Bangor and Caernarvon, were identified as Ordovician, not Cambrian. Very detailed map-work in Anglesey was carried out privately by Edward Greenly, and his results were published by the Survey in the form of a map and a high-quality Memoir. Greenly utilized for Anglesey tectonic ideas derived from his earlier fieldwork in the Scottish Highlands, so that although his mapping and stratigraphical divisions have proved to be of permanent value it is believed that his structures for Anglesey were mistaken and his stratigraphic sequence inverted. The Survey eventually abandoned its earlier (Ramsay) model of Anglesey without too much difficulty; and the igneous ‘rib’ of Llyn Padarn is now construed as an ignimbrite. However, a definite base for the Cambrian has still not been found in Caernarvonshire, and the stratigraphical evidence for the Precambrian age of the Anglesey rocks (by perceived unconformity with known Cambrian strata) remains incomplete. The study reveals the great difficulty experienced by early geologists when working in unfossiliferous rocks, the evidence from included fragments proving particularly uncertain. The paper also examines further the community of nineteenth-century British geologists, with their various factions and competing interests.  相似文献   

16.
Archive for History of Exact Sciences - The claim that Galileo Galilei (1564–1642) transformed the spyglass into an astronomical instrument has never been disputed and is considered a...  相似文献   

17.
Deficiency in cerebral amyloid β-protein (Aβ) clearance is implicated in the pathogenesis of the common late-onset forms of Alzheimer’s disease (AD). Accumulation of misfolded Aβ in the brain is believed to be a net result of imbalance between its production and removal. This in turn may trigger neuroinflammation, progressive synaptic loss, and ultimately cognitive decline. Clearance of cerebral Aβ is a complex process mediated by various systems and cell types, including vascular transport across the blood–brain barrier, glymphatic drainage, and engulfment and degradation by resident microglia and infiltrating innate immune cells. Recent studies have highlighted a new, unexpected role for peripheral monocytes and macrophages in restricting cerebral Aβ fibrils, and possibly soluble oligomers. In AD transgenic (ADtg) mice, monocyte ablation or inhibition of their migration into the brain exacerbated Aβ pathology, while blood enrichment with monocytes and their increased recruitment to plaque lesion sites greatly diminished Aβ burden. Profound neuroprotective effects in ADtg mice were further achieved through increased cerebral recruitment of myelomonocytes overexpressing Aβ-degrading enzymes. This review summarizes the literature on cellular and molecular mechanisms of cerebral Aβ clearance with an emphasis on the role of peripheral monocytes and macrophages in Aβ removal.  相似文献   

18.
19.
Adenosine is an endogenous signaling molecule upregulated during inflammatory conditions. Acting through the A2b receptor (A2bR), the predominant adenosine receptor in human colonic epithelia, adenosine has been directly implicated in immune and inflammatory responses in the intestine. Little is known about expression and regulation of A2bR during inflammation. Tumor necrosis factor alpha (TNF-α) is highly upregulated during chronic and acute inflammatory diseases. This study examined the expression of A2bR during colitis and studied effects of TNF-α on A2bR expression, signaling and function. Results demonstrated that A2bR expression increases during active colitis. TNF-α pretreatment of intestinal epithelial cells increased A2bR messenger RNA and protein expression. TNF-α significantly increased adenosine-induced membrane recruitment of A2bR and cyclic adenosine monophosphate downstream signaling. Further, TNF-α potentiated adenosine-induced shortcircuit current and fibronectin secretion. In conclusion, we demonstrated that TNF-α is an important regulator of A2bR, and during inflammation, upregulation of TNF-α may potentiate adenosine-mediated responses. Received 21 July 2005; received after revision 22 August 2005; accepted 19 September 2005 †These authors contributed equally to this work.  相似文献   

20.
Climate change is one of the greatest threats to humanity and requires immediate action. Schuldt, Konrath, and Schwarz (2011) suggested that beliefs in environmental phenomena can be influenced by the terminology used to describe it: changing question wording from global warming to climate change resulted in a 6.3 percentage point increase in belief in environmental phenomena. This association was moderated by political self-identification, with Republicans being 16.2 percentage points more likely to believe in climate change than in global warming, with Democrats showing no difference. The potential for connotative meanings to shift over time and the sociopolitical changes since the original study, potential policy and environmental campaign implications, and an expansion of these findings to other countries, motivated an attempt to replicate this important finding. This pre-registered study repeated the original procedures in the United States of America and two other countries (United Kingdom and Australia; total N = 5,717). Although question wording no longer had a significant effect on beliefs in climate change/global warming, the association of political self-identification with beliefs in environmental phenomena replicated in all three countries, with Conservatives consistently believing less in climate change/global warming than Liberals. The potential impacts of temporal and methodological differences on the discrepancies between this study's and the original's findings are discussed.  相似文献   

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