1,723 research outputs found
Challenging the Death Penalty for Mentally Retarded Defendants: Issues Raised by Penry v. Lynaugh
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
Extended diffeomorphism algebras in (quantum) gravitational physics
We construct an explicit representation of the algebra of local
diffeomorphisms of a manifold with realistic dimensions. This is achieved in
the setting of a general approach to the (quantum) dynamics of a physical
system which is characterized by the fundamental role assigned to a basic
underlying symmetry. The developed mathematical formalism makes contact with
the relevant gravitational notions by means of the addition of some extra
structure. The specific manners in which this is accomplished, together with
their corresponding physical interpretation, lead to different gravitational
models. Distinct strategies are in fact briefly outlined, showing the
versatility of the present conceptual framework.Comment: 20 pages, LATEX, no figure
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
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