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

Tomographic resolution of ray and finite-frequency methods: A membrane-wave investigation

The purpose of this study is to evaluate the resolution potential of current finite-frequency approaches to tomography, and to do that in a framework similar to that of global scale seismology. According to our current knowledge and understanding, the only way to do this is by constructing a large set of ‘ground-truth' synthetic data computed numerically (spectral elements, finite differences, etc.), and then to invert them using the various available linearized techniques. Specifically, we address the problem of using surface wave data to map phase-velocity distributions. Our investigation is strictly valid for the propagation of elastic waves on a spherical, heterogeneous membrane, and a good analogue for the propagation of surface waves within the outermost layers of the Earth. This amounts to drastically reducing the computational expense, with a certain loss of accuracy if very short-wavelength features of a strongly heterogeneous Earth are to be modelled. Our analysis suggests that a single-scattering finite-frequency approach to tomography, with sensitivity kernels computed via the adjoint method, is significantly more powerful than ray-theoretical methods, as a tool to image the fine structure of the Eart