Spike-like Peaks Research Articles

An ultrasonic study of spin-density-wave effects in a Cr+0.2 at. % Ir alloy single crystal

Measurements of the temperature dependences of the second-order elastic constants and attenuation of ultrasonic waves through the magnetic phase transition temperatures of a Cr+0.2 at. % Ir alloy single crystal are reported. The incommensurate–commensurate spin-density-wave transition is marked by steplike decreases, accompanied by hysteresis of width about 16 K, in all the elastic constants on heating through the transition temperature. The attenuation coefficient shows a spikelike peak at this transition. A deep minimum in c11 and small peaks in c44 and 1/2 (c11−c12) are observed at the Néel transition.

Numerical Simulation of Rectangle Ice Floes Movement Using a Distributed Mass/Discrete Floe Model

A new model, named “Distributed Mass/Discrete Floe model” is proposed for numerical simulation of short term and narrow area pack ice movement. This model possesses the advantages of both the continuum and the discrete element ones: it can express the discrete nature of pack ice which is difficult for a continuum model to treat, and it can realize much shorter computation time than a discrete element model. The pack ice is divided into ice floe bunches in which the floes, assumed to be distributed uniformly, are modeled as inelastic rectangles floating on the water. The ice interaction forces are formulated from the relation between the impulse on the bunch and the variation of the bunch momentum. The ocean flow is calculated by a multi-layer model simultaneously with the ice floe movement. The model formulation and the improvement of the computation accuracy are described in detail.The computations were made for simplified ocean conditions driven by a uniform wind field in the marginal ice zones between the coast and offshore. The results showed some characteristics of ice and water combined flow and force acting on an ocean structure, as follows;1. The water surface velocity distribution is distorted by the difference in the shear stress between the water/ice interface and the water/air interface. This causes the diffusion of pack ice.3. In the case of no major current for a deep ocean, the water surface velocity can be determined from the computation only for a scale of the Ekman layer. If the water depth is less than the scale of Ekman layer, the direction of water surface flow, which is essential for the ice flow calculation, is highly affected by the water depth.3. Many spike-like peaks appeard in the time variation of ice load on an ocean structure. This is caused by the discrete nature of the present model. Also, the results showed the rational movement of pack ice around the structure.

Adsorption behavior of viologen derivatives on hanging mercury electrode surfaces

The adsorption behavior of N, N′-dialkyl-4,4′-bipyridinium dications (viologens) on hanging mercury electrode surfaces was investigated as a function of the alkyl chain length (C n V 2+, n = 1–8). Monolayer adsorbed viologens give a pair of very narrow spike-like peaks on cyclic voltammograms, which can be attributed to the redox electrode reaction. The peak location was found to depend on both the alkyl chain length and the bulk concentration, and is shifted to a more positive potential with increasing chain length. These facts suggest strongly that the lateral interaction between alkyl chains of viologen molecules plays an important role in the stabilization of the structure of adsorbed layers.

An intracellular study of Renshaw cells

Intracellular recordings were made from Renshaw cells in the cat. Recurrent excitatory postsynaptic potentials (EPSPs) were elicited by antidromic stimulation of the ventral roots. These EPSPs has a simple monophasic time course without a spike-like peak reported by previous authors. No hyperpolarization could be detected following averaged EPSPs. However, after bursts of impulses an afterhyperpolarization could be detected which probably contributes to a pause in firing after the initial response. Depolarizing current pulses elicited a burst of impulses similar in pattern to the initial response to stimulation of the ventral roots.