310,473 research outputs found
Parabole e catastrofi. Intervista a René Thom
No full textSi tratta di un libro intervista a René Thom sul significato filosofico della sua teori
Prefazione a: René Thom: Prevedere non è spiegare
No full textsi inquadra la ristampa in nuova edizione italiana dello scritto di Thom nella sua concezione generale della matematica di tipo qualitativo e relazionale e non banalmente quantitativo con riferimento sia all'adesione di Thom alla visione aristotelica della scienza sia alla sua teoria delle catastrofi e al suo approccio modellistico e dinamico. Se ne illustrano quindi sia gli aspetti filosofico-epistemologici sia quelli più tecnic
Dados e perspectivas na gestão de ideias: fatores internos e externos que influenciam de forma positiva a eficiência da gestão de ideias
No full textHá quatro décadas que o Prof. Dr. Norbert Thom interessa-se pelo Betriebliches Vorschlagswesen (BVW), sistema empresarial de sugestões e seu desenvolvimento à atual gestão de ideias, Ideenmanagement (IM). Tanto na Alemanha como na Suíça, ele realizou um grande número de estudos empíricos com seus assistentes e estudantes. Um processo de pesquisa de longo prazo refletiu persistentemente sobre uma questão central: Como será possível motivar o maior número de trabalhadores a contribuir, por meio de ideias construtivas e criativas, para o aperfeiçoamento contínuo de processos e atividades empresariais
E. J. Hughes
No full textThom surveys Hughes’ career from the 1930s to 2002 in this book produced in conjunction with a major retrospective of the artist’s work. A portrait of Hughes’ peripatetic life in British Columbia and elsewhere, it includes an account of his experience as a war artist and focuses on the significant influence of his dealer, Max Stern, and their correspondence. Bibliography (1 p.) and chronology (1 p.) 2 maps. Index of works. Circa 100 bibl. ref
Glass formation in upper tropospheric aerosol particles
No full textPedernera de Neuhaus DA. Glasbildung in Aerosolpartikeln der oberen Troposphäre. Bielefeld (Germany): Bielefeld University; 2008.Over the last two decades the chemical composition of atmospheric aerosols has changed significantly. Recent field measurements have shown that atmospheric aerosol particles in the upper tropical troposphere contain increasing quantities of organic solutes. At the same time it has been observed that in those aerosols the formation of cirrus clouds is inhibited.
In this work a new process is presented, that might retard or even entirely impede ice nucleation, ice growth as well as the water uptake of atmospheric aerosol particles in the upper troposphere: the formation of glassy aerosol particles.
The glass transition temperatures, Tg, homogeneous ice nucleation temperatures, Thom, and ice melting temperatures, Tm, of various aqueous organic, inorganic and mixed solutions were investigated with a differential scanning calorimeter. The following water-soluble compounds were investigated in binary and ternary aqueous solutions with different mass mixing ratios: glucose, levoglucosan, glutaric acid, 1,4-butanediol, H2SO4, NH4NO3, NH4HSO4, Ca(NO3)2 and NaNO3.
The results of these experiments are presented by means of state diagrams. They reveal that aqueous solutions containing atmospherically relevant inorganic solutes such as NH4NO3 or H2SO4 exhibit only very low Tg-values below 180 K. Therefore, it is expected that atmospheric aerosol particles of such inorganic solutions exist in the liquid or in the crystalline state, but not as glasses. In contrast, aqueous solutions of the investigated organic compounds tend to form glasses at atmospherically relevant temperatures.
In order to apply the laboratory data to the atmospheric situation, the measured phase transition temperatures Tg, Thom and Tm were transformed from the concentration scale to the water activity scale by parameterizing water activities determined experimentally.
The results show that both ice nucleation and ice growth in aqueous organic-enriched aerosol particles can be considerably reduced or even completely inhibited, which can explain the observed inhibition of cirrus cloud formation in the upper tropical troposphere.Im Laufe der letzten zwei Jahrzehnte hat sich die Zusammensetzung atmosphärischer Aerosole stark verändert. Feldmessungen haben kürzlich gezeigt, dass atmosphärische Aerosolpartikel der oberen tropischen Troposphäre immer größere Mengen an organischen Substanzen enthalten. Gleichzeitig wurde in diesen Aerosolen eine Hemmung der Eiswolkenbildung beobachtet.
In dieser Arbeit wird ein neuer Mechanismus präsentiert, welcher die Eisnukleation, das Eiswachstum und die Wasseraufnahme in atmosphärischen Aerosolpartikeln unter den in der oberen Troposphäre herrschenden Bedingungen (wie etwa Temperaturen zwischen 180 und 200 K) verlangsamen oder verhindern kann: die Bildung glasartiger Aerosolpartikel.
Die Temperatur der Glasumwandlung, Tg, der homogenen Eisnukleation, Thom, und des Eisschmelzens, Tm, diverser wässriger Systeme aus organischen und/oder anorganischen Substanzen wurde mittels dynamischer Kalorimetrie experimentell bestimmt. Die Substanzen Glucose, Levoglucosan, Glutarsäure, 1,4-Butandiol, H2SO4, NH4NO3, NH4HSO4, Ca(NO3)2 und NaNO3 wurden dabei in verschiedenen Massenverhältnissen in binären und ternären wässrigen Lösungen untersucht.
Die aus diesen Messungen erhaltenen Phasendiagramme zeigen, dass wässrige Lösungen aus atmosphärisch relevanten anorganischen Substanzen wie H2SO4 oder NH4NO3 nur sehr niedrige Tg-Werte unterhalb 180 K aufweisen. Es ist daher zu erwarten, dass die entsprechenden atmosphärischen Aerosolpartikel im flüssigen oder im kristallinen Zustand vorliegen, nicht jedoch als Glas. Dagegen neigen wässrige Lösungen der untersuchten organischen Verbindungen zu einer Glasbildung.
Um diese im Labor experimentell bestimmten Daten auf die Atmosphäre anwenden zu können, wurden die Temperaturen Tg, Thom und Tm von der Konzentrationsskala mit Hilfe von Messungen und entsprechenden Parametrisierungen in die Wasseraktivitätsskala umgewandelt.
Die Ergebnisse zeigen, dass sowohl die Eisnukleation als auch das Eiswachstum in wässrigen organischen Aerosolpartikeln erheblich reduziert oder gar vollständig unterbunden werden können, was die beobachtete Hemmung der Eiswolkenbildung in der oberen tropischen Troposphäre erklären kann
Clark, Mrs. Thom. E. (baby)
No full textPhotograph from the C.R. Savage Portrait Studio. Name associated with the photograph: Mrs. Thom. E. Clar
Maxwell Bates
No full textThom presents a brief introduction to the life and work of Bates. 6 bibl. ref
Anne Popperwell : Watercolours
No full textThom introduces Popperwell's paintings, inspired by the landscape of Saturna Island. Biographical notes. 1 bibl. ref
Joan Martin : Gardens of the Italian Renaissance
No full textThom introduces Martin's drawings of gardens and architecture of Rome. Biographical notes
Geologic atlas of the United States : topography, areal geology, economic geology, structure sections / 70 Washington Folio : District of Columbia - Maryland - Virginia
No full textN. H. Darton ; Arthur Keith; H. M. Wilson ; J. D. Hoffman ; D. J. Howell ; A. E. Murlin ; J. H. Jennings ; M. Hackett ; W. M. Beaman ; H. Munroe ; A. Pike ; R. Muldrow ; W. J. Lloyd ; J. W. Thom ; A. M. Walker ; E. B. Clark ; G. E. HydeList of Sheets: Topography, Historical Geology, Economic Geology, Structure Sections, Physiographic GeologyIndirektes handschriftliches Exlibris: "1901, 594", das ist Geological Survey U. S. Washington Exemplar der ETH-BI
- …
