The hydro-kinetic theory of liquid helium II

In Part I the kinetic theory of excitations in flowing liquid He II is developed to a higher order than that carried out previously, by Landau and Khalatnikov, in order to demonstrate the existence of non-equilibrium terms of a new nature in the hydrodynamic equations. It is then shown that these terms can lead to spontaneous destabilization in counter currents when the relative velocity of the normal and super fluids exceeds a critical value that depends on the temperature, but not on geometry. There are no adjustable parameters in the theory. The critical velocities are estimated to be in the 14-20 m/sec range for T ≤ 2.0° K, but tend to zero as T → T_λ. The possibility that these critical velocities may be related to the experimentally observed "intrinsic" critical velocities is discussed.

Part II consists of a semi-classical investigation of rotonquantized vortex line interactions. An essentially classical model is used for the collision and the behavior of the roton in the vortex field is investigated in detail. From this model it is possible to derive the HVBK mutual friction terms that appear in the phenomenalogical equations of motion for rotating liquid He II. Estimates of the Hall and Vinen B and B' coefficients are in good agreement with experiments. The claim is made that the theory does not contain any arbitrary adjustable parameters.

A. An investigation of the relation between the tensile strength and (Brinell) hardness of non-ferrous alloys. B. A design of a fatigue testing machine for a college laboratory

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Neocarzinostatin chromophore: structural, mechanistic, and synthetic studies

Neocarzinostatin chromophore 1 is the active component of the antitumor antibiotic neocarzinostatin (NCS). The chromophore reacts with thiols to form a highly strained cumulene-enyne species which rapidly rearranges to a biradical intermediate which can abstract hydrogen atoms from DNA, leading to strand cleavage. DNA damage is the proposed source of biological activity for NCS. The structure of the methyl thioglycolate monoadduct 2 of NCS chromophore, including the absolute stereochemistry, was determined by NMR studies. The presence of the cumulene-enyne intermediate and the rearrangement to a biradical were supported by data from low temperature NMR investigations. Also included are synthetic approaches to NCS chromophore model compounds based on intramolecular addition of an acetylide to an aldehyde.

Circadian clock mutants of Drosophila melanogaster

Three mutants of Drosophila melanogaster have been isolated in which the free-running period of the circadian eclosion rhythm and the adult locomotor activity rhythm is affected. One mutant is arrhythmic, another has a short period of 19 hours, and the third has a long period of 28 hours. The mutants retain their phenotypes over the temperature range 18° to 25° C. All three mutants map near the tip of the X chromosome (distal to the centromere). By deficiency mapping, the short-period mutation has been localized to the 3B1-2 region. Complementation tests show that all three mutations affect the same functional gene.

Analysis of activity rhythms of individual mosaic flies indicates that the site of action of the short-period mutation is probably located in the head of the fly. A few activity patterns of split-head and mixed-head mosaics appear to possess both mutant and heterozygous components, suggesting that the fly head may contain two complete clocks capable of maintaining their periodicities independently.

The short-period mutation affects both the duration of the light-insensitive part of the oscillation and the degree to which the clock can be reset during the light-sensitive part of the oscillation.

Both the short-period and long-period mutant eclosion rhythms can be entrained to a period of 24 hours by a 12:12 light-dark cycle having a light intensity at least two orders of magnitude greater than that required to entrain the normal rhythm. The arrhythmic mutant does not entrain under these conditions. In the presence of a temperature cycle, however, the arrhythmic mutant does entrain, but its rhythm damps out when the temperature cycle is removed.

Evidence is presented that Pittendrigh's two-oscillator model for the clock in D. pseudoobscura applies to D. melanogaster as well. The three clock mutations primarily affect the light- sensitive driving oscillator. The arrhythmic mutation appears to have eliminated the driving oscillator while leaving the temperature-sensitive driven oscillator relatively intact.