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61.
Peirce and Beer   总被引:1,自引:1,他引:0  
This paper considers the philosophical background of Stafford Beer's Viable Systems Diagnosis (VSD) as profoundly influenced by Charles Peirce. In a general sense, our work discusses the VSD theory base in the development of a model for actionable theory in organizations. This paper examines VSD theory in the Beer trilogy ‘Brain of the Firm,’ ‘The Heart of the Enterprise’ and ‘Diagnosing the System’ and we propose that a sound set of VSD action principles can be derived from this trilogy. We contend that the philosophical background underpinning these principles is important. Using Beer’s ‘Decision and Control,’ we consider that philosophical background and link Operational Research and the interdisciplinary learning within Cybernetics to modern general systems theory. We explore Beer’s viewpoint on the Peirce depiction of four main methods of fixing belief; tenacity, authority, a priori and finally the scientific to assist in that expansion. We consider how knowledge of Beer’s perspective on making sense of the world is important in the linkage of VSD theory to the managerial problem arena. We relate the Peirce methods to previously reported problem solving exercises involving the VSD ideology, which we will develop individually at a later date. This paper reflects our desire to express the interpretation of VSD theory in a language that the well-informed manager may readily translate into the third step of testing theory in practice.  相似文献   
62.
The protein-kinase family is the most frequently mutated gene family found in human cancer and faulty kinase enzymes are being investigated as promising targets for the design of antitumour therapies. We have sequenced the gene encoding the transmembrane protein tyrosine kinase ERBB2 (also known as HER2 or Neu) from 120 primary lung tumours and identified 4% that have mutations within the kinase domain; in the adenocarcinoma subtype of lung cancer, 10% of cases had mutations. ERBB2 inhibitors, which have so far proved to be ineffective in treating lung cancer, should now be clinically re-evaluated in the specific subset of patients with lung cancer whose tumours carry ERBB2 mutations.  相似文献   
63.
Characterizing fine-scale variation in human recombination rates is important, both to deepen understanding of the recombination process and to aid the design of disease association studies. Current genetic maps show that rates vary on a megabase scale, but studying finer-scale variation using pedigrees is difficult. Sperm-typing experiments have characterized regions where crossovers cluster into 1-2-kb hot spots, but technical difficulties limit the number of studies. An alternative is to use population variation to infer fine-scale characteristics of the recombination process. Several surveys reported 'block-like' patterns of diversity, which may reflect fine-scale recombination rate variation, but limitations of available methods made this impossible to assess. Here, we applied a new statistical method, which overcomes these limitations, to infer patterns of fine-scale recombination rate variation in 74 genes. We found extensive rate variation both within and among genes. In particular, recombination hot spots are a common feature of the human genome: 47% (35 of 74) of genes showed substantive evidence for a hot spot, and many more showed evidence for some rate variation. No primary sequence characteristics are consistently associated with precise hot-spot location, although G+C content and nucleotide diversity are correlated with local recombination rate.  相似文献   
64.
Zusammenfassung Bei zwei verschiedenen Explantaten von Telencephalogewebe 14tägiger Hühnchenembryonen ergab sich als Temperaturabhängigkeit der Aktionspotentiale: Frequenz und Amplitudenabnahme bei sinkender, Zunahme bei steigender Temperatur bis zwischen 37 und 42,5°C. Weitere Temperatursteigerung bringt die Potentiale nach stetiger Verkleinerung bei 47°C schliesslich zum Verschwinden.

This research was supported by a grant from the Office of Naval Research, U.S. Navy Contract NONR 1598(04).  相似文献   
65.
Modulation of electrical activity in Aplysia neurones by cholesterol   总被引:2,自引:0,他引:2  
C L Stephens  M Shinitzky 《Nature》1977,270(5634):267-268
  相似文献   
66.
Thomas GA  Shraiman BI  Glodis PF  Stephens MJ 《Nature》2000,404(6775):262-264
An important scientific and technological goal in the field of optical communications is the achievement of the clarity limit in optical fibres--that is, ensuring that the SiO2 glass from which fibres are made is as transparent as possible. The clarity of the wavelength transmission window (and the width of that window) in existing fibres is already sufficient to form the basis of a world-wide optical communication system, yet it is still limited by contamination of the fibre by water. Here we measure the spatial distribution of water in the glass rods from which optical fibres are drawn and explain the distribution quantitatively with a mathematical model of diffusion in a medium with essentially perfect cylindrical symmetry. Our analysis shows that the water enters from the outside of the rod and diffuses into the molten, flowing glass much faster than is expected from extrapolation of low-temperature measurements. Our elucidation of the physics underlying the contamination process has already led to the fabrication of dry fibres, which have a clarified and broadened communications window. The improved operational range of wavelengths should yield applications for new lasers, optical amplifiers and detectors, and should substantially increase the information-carrying capacity of optical communications systems.  相似文献   
67.
Phosphoinositide-3-OH kinases (PI(3)Ks) constitute a family of evolutionarily conserved lipid kinases that regulate a vast array of fundamental cellular responses, including proliferation, transformation, differentiation and protection from apoptosis. PI(3)K-mediated activation of the cell survival kinase PKB/Akt, and negative regulation of PI(3)K signalling by the tumour suppressor PTEN (refs 3, 4) are key regulatory events in tumorigenesis. Thus, a model has arisen that PI(3)Ks promote development of cancers. Here we report that genetic inactivation of the p110gamma catalytic subunit of PI(3)Kgamma (ref. 8) leads to development of invasive colorectal adenocarcinomas in mice. In humans, p110gamma protein expression is lost in primary colorectal adenocarcinomas from patients and in colon cancer cell lines. Overexpression of wild-type or kinase-dead p110gamma in human colon cancer cells with mutations of the tumour suppressors APC and p53, or the oncogenes beta-catenin and Ki-ras, suppressed tumorigenesis. Thus, loss of p110gamma in mice leads to spontaneous, malignant epithelial tumours in the colorectum and p110gamma can block the growth of human colon cancer cells.  相似文献   
68.
69.
The nineteenth-century American scientist, philosopher and teacher Joseph LeConte (1823–1901) is well-known for his writings on geology and the reconciliation of evolutionary theory and religion, but he has not been properly recognized for his contributions to the physiology and psychology of vision. This study explores and assesses his work in the latter field, showing the nature of his original investigations into human vision and the influence of his book Sight: an exposition of the principles of monocular and binocular vision, which served as the major textbook on the subject in the United States from its publication in 1881 until after the turn of the century. Grounded in neo-Lamarckian evolutionary theory, LeConte's publications on vision had a strong impact upon subsequent studies of the phenomenon of human sight.  相似文献   
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