ALBERT

Notes: Zusammenfassung Insektenjuvenilhormone und -analoge wurden an verschiedenen freilebenden und parasitischen Nematoden getestet. BeiNeoaplectana carpocapsae wurden toxische Effekte und beiCaenorhabditis briggsiae Reifungshemmung festgestellt.

Notes: Abstract One of the most promising implications of the phenomenological Ginzburg—Landau (GL) theory of superconductivity is the possible existence of current-carrying metastable states with a negative effective self-inductance. Microscopically this phenomenon can be explained as a result of the depairing mechanism which, when the center-of-mass velocityv s of the Cooper pairs is sufficiently large, can be so strong that a further increase ofv s will lead to a decrease of the total current. Using a one-dimensional formulation of the GL theory we investigate the thermodynamic stability of these states for different external constraints and obtain the result that a negative self-inductance can only be stable if the length of the system in the direction of the current is smaller than a critical value comparable to the GL coherence length λ/κ. It is an experimental fact that states of negative self-inductance are realized in Josephson junctions and other types of superconducting weak links because the dc supercurrent can be a decreasing function of the phase variable φ. The thermodynamic stability theory can therefore explain why weak links have to be short, and it also provides us with a unifying point of view by treating the phase φ and the current as a pair of thermodynamically conjugate variables for arbitrary one-dimensional systems. An important point is the operational phase definition as a thermodynamic parameter that can be controlled by the experimentalist. This requirement is essential for the general validity of the ac Josephson equation and it implies that φ must depend on the magnetic self-inductance of the system. By applying the GL theory to weak links we can delimit the validity of the usual dc Josephson equationI ∝ sin φ and see that deviations from this functional form are most likely to be found in thin-film bridges of the Anderson-Dayem (AD) type. When the currentI is the controlled variable the conjugate phase variable φ will fluctuate and the magnitude of these fluctuations depends strongly on the functional formI(φ). The phase fluctuations for constantI lead to a reduction of the critical current which will be absent when φ is the controlled variable. The observed microwave enhancement of the critical current in AD bridges, the so-called Dayem effect, can be explained as a result of a switch from current control to phase control, and the fluctuation formulae explain why the effect is negligible in structures exhibiting the classical Josephson sine law for the current-phase relation.

Notes: Summary The effects were studied of varying amounts and forms of N fertilizers on the chemical composition of soil solution and on the uptake of N, K, Na, Ca and Mg by barley. In isolated soil solution the concentrations as well as the ratios of individual cations depended on form and amount of added nitrogen. The concentration of Σcations increased proportionally with applications of nitrate+sulphate. Cation-activity ratios in isolated soil solution were governed by the ratios of corresponding exchangeable cations. During the entire growth period the absorption by the plants of individual as well as of Σcations was independent of their concentrations in soil solution. So long as NH4 ions were present in the soil solution, plants with NH4 addition contained less Σcations than those with NO3 addition. Thereafter the amounts of Σcations in the plant were closely correlated with N absorption, but not affected by form of applied N. The ratios K/(Ca+Mg) and Ca/Mg in the plant were closely correlated with corresponding activity ratios but independent of concentration ratios of these ions in isolated soil solution. It is postulated that uptake of Σcations is governed by N-metabolic processes in the plant, whereas ratios of absorbed cations are influenced by cation-activity ratios in the soil solution.