2,049 research outputs found
Amino Acids of Mouse Skin During Treatment with Carcinogenic Hydrocarbons
SINCE collagen is rich in hydroxyproline and practically devoid of tyrosine, alterations in the amounts of these amino acids should afford a good indication of changes in skin collagen content which might be induced by the application of carcinogens. Hamer and Marchant (1957) in experiments carried out in this laboratory found little change in the tyrosine content of the skins of mice, a slight decrease in the hydroxyproline content of skin from male mice but little change in female skin, after 12 weekly applications of 0 3 per cent methylcholanthrene in acetone. From these observations, in conjunction with parallel extractions of the collagen and acid-soluble (procollagen) fractions, and analyses of the polysaccharide and ground-substance components, they concluded that physical changes in the state of association of the collagen rather than changes in chemical composition, are responsible for the effects of carcinogens that have been observed histologically (Orr, 1938; Vernoni, 1951). UTnfortunately values at intermediate periods of treatment were not determined
Quantization Of Cyclotron Motion and Quantum Hall Effect
We present a two dimensional model of IQHE in accord with the cyclotron
motion. The quantum equation of the QHE curve and a new definition of filling
factor are also given.Comment: 13 Pages, Latex, 1 figure, to appear in Europhys. Lett. September
199
Time and Geometric Quantization
In this paper we briefly review the functional version of the Koopman-von
Neumann operatorial approach to classical mechanics. We then show that its
quantization can be achieved by freezing to zero two Grassmannian partners of
time. This method of quantization presents many similarities with the one known
as Geometric Quantization.Comment: Talk given by EG at "Spacetime and Fundamental Interactions: Quantum
Aspects. A conference to honour A.P.Balachandran's 65th birthday
Symplectic Cuts and Projection Quantization
The recently proposed projection quantization, which is a method to quantize
particular subspaces of systems with known quantum theory, is shown to yield a
genuine quantization in several cases. This may be inferred from exact results
established within symplectic cutting.Comment: 12 pages, v2: additional examples and a new reference to related wor
Quantum-Mechanical Dualities on the Torus
On classical phase spaces admitting just one complex-differentiable
structure, there is no indeterminacy in the choice of the creation operators
that create quanta out of a given vacuum. In these cases the notion of a
quantum is universal, i.e., independent of the observer on classical phase
space. Such is the case in all standard applications of quantum mechanics.
However, recent developments suggest that the notion of a quantum may not be
universal. Transformations between observers that do not agree on the notion of
an elementary quantum are called dualities. Classical phase spaces admitting
more than one complex-differentiable structure thus provide a natural framework
to study dualities in quantum mechanics. As an example we quantise a classical
mechanics whose phase space is a torus and prove explicitly that it exhibits
dualities.Comment: New examples added, some precisions mad
Noncentral extensions as anomalies in classical dynamical systems
A two cocycle is associated to any action of a Lie group on a symplectic
manifold. This allows to enlarge the concept of anomaly in classical dynamical
systems considered by F. Toppan [in J. Nonlinear Math. Phys. 8, no.3 (2001)
518-533] so as to encompass some extensions of Lie algebras related to
noncanonical actions.Comment: arxiv version is already officia
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