5,333 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
Short laws for finite groups and residual finiteness growth
No full text We prove that for every n ∈ N n \in \mathbb {N} and δ > 0 \delta >0 there exists a word w n ∈ F 2 w_n \in F_2 of length O ( n 2 / 3 log ( n ) 3 + δ ) O(n^{2/3} \log (n)^{3+\delta }) which is a law for every finite group of order at most n n . This improves upon the main result of Andreas Thom [Israel J. Math. 219 (2017), pp. 469–478] by the second named author. As an application we prove a new lower bound on the residual finiteness growth of non-abelian free groups. </p
Screening for illicit drug use in psychiatric hospitals: whose job is it?
No full textThom conducted the original work and produced the report (sole author). The publication was extracted/ adapted from the report and a few additions made by Crome and Bloor. They wrote the paper and Thom commented / supervised
Generalized Thom spectra and topological Hochschild homology
No full textThis is joint work with S. Basu and S. Sagave.
We consider -algebra Thom spectra for a commutative symmetric (or orthogonal) ring spectrum and analyze their topological Hochschild homology. As an example, we consider generalized Thom ring spectra based on and show how their topological Hochschild homology may depend on the multiplicative structure. Time permitting, we also discuss graded Thom spectra and the relation to logarithmic topological Hochschild homology.Non UBCUnreviewedAuthor affiliation: University of BergenFacult
GENERALIZED THOM SPECTRA AND THEIR TOPOLOGICAL HOCHSCHILD HOMOLOGY
No full textWe develop a theory of -module Thom spectra for a commutative symmetric ring spectrum and we analyze their multiplicative properties. As an interesting source of examples, we show that -algebra Thom spectra associated to the special unitary groups can be described in terms of quotient constructions on . We apply the general theory to obtain a description of the -based topological Hochschild homology associated to an -algebra Thom spectrum.</jats:p
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
Perfectoid rings as Thom spectra
No full textThe Hopkins-Mahowald theorem realizes the Eilenberg-Maclane spectra as Thom spectra for all primes . In this article, we record a known proof of a generalization of Hopkins-Mahowald theorem, realizing as Thom spectra for perfect rings , and we provide a further generalization by realizing as Thom spectra for perfectoid rings . We also discuss even further generalizations to prisms and indicates how to adapt our proofs to Breuil-Kisin case.Minor updates (including some numbering and some typesetting change). Two references about the iterated loop space of the 3-sphere are adde
Thom polynomials with integer coefficients
No full textThe Thom polynomial of a singularity is a universal characteristic class that expresses the cohomology class represented by a singularity locus. In this paper we compute the Thom polynomials of real singularities up to codimension 8 in cohomology with integer coefficients
La philosophie de Thomas d'Aquin. Repères. R. Imbach, A. Oliva
No full textDeux comptes-rendus divergents de l'ouvrage de Ruedi Imbach et Adriano Oliva. La philosophie de Thomas d’Aquin. Repères, Paris, Vrin, 2009, 180 p.; ISBN 978-2-7116-2232-0; 12 €. Présentation de quatrième de couverture: Le livre que le lecteur tient en main peut être comparé à un guide de voyage, il voudrait aider le lecteur à découvrir la pensée philosophique de Thomas d’Aquin, à se déplacer et se mouvoir dans cet univers que représente l’œuvre intellectuelle du dominicain italien. Le sous-ti..
Sofic groups and diophantine approximation
No full textWe prove the algebraic eigenvalue conjecture of J. Dodziuk, P. Linnell, V. Mathai, T. Schick, and S. Yates (see [2]) for sofic groups. Moreover, we give restrictions on the spectral measure of elements in the integral group ring. Finally, we define integer operators and prove a quantization of the operator norm below 2. To the knowledge of the author, there is no group known that is not sofic. (c) 2007 Wiley Periodicals, Inc
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