Controlling the partial coalescence of a droplet on a vertically vibrated bath

A new method is proposed to stop the cascade of partial coalescences of a droplet laid on a liquid bath. The strategy consists in vibrating the bath in the vertical direction in order to keep small droplets bouncing. Since large droplets are not able to bounce, they partially coalesce until they reach a critical size. The system behaves as a low pass filter : droplets smaller than the critical size are selected. This size has been investigated as a function of the acceleration and the frequency of the bath vibration. Results suggest that the limit size for bouncing is related to the first mode of the droplet deformation.Comment: 4 pages, 3 figures, accepted in Phys. Rev.

Asymmetry-Driven Structure Formation in Pair Plasmas

The nonlinear propagation of electromagnetic waves in pair plasmas, in which the electrostatic potential plays a very important but subdominant role of a "binding glue" is investigated. Several mechanisms for structure formation are investigated, in particular, the "asymmetry" in the initial temperatures of the constituent species. It is shown that the temperature asymmetry leads to a (localizing) nonlinearity that is new and qualitatively different from the ones originating in ambient mass or density difference. The temperature asymmetry driven focusing-defocusing nonlinearity supports stable localized wave structures in 1-3 dimensions, which, for certain parameters, may have flat-top shapes.Comment: 23 pages, 6 figures, introduction revised, edited typos, accepted for publication in Phys. Rev.

Acceleration of Plasma Flows Due to Reverse Dynamo Mechanism

The "reverse-dynamo" mechanism - the amplification/generation of fast plasma flows by micro scale (turbulent) magnetic fields via magneto-fluid coupling is recognized and explored. It is shown that macro-scale magnetic fields and flows are generated simultaneously and proportionately from micro scale fields and flows. The stronger the micro-scale driver, the stronger are the macro-scale products. Stellar and astrophysical applications are suggested.Comment: 16 pages including 3 figures. The Astrophys. J. (accepted); additional material is given for clarification; terminology is change

The Optical Hygrometer and its Working

In this paper, the description of the construction of the optical hygrometer is given. It works on the principle of a balance in the form of a rod supported by two loose screws and at right angles to it there is another rod having two pans on its ends, rigidly Attached with it. One pan contains the substance having high power of absorption and desorption of moisture and the other pan balancing weights. the rotation of the rod which is proportional to the change in humidity is measured by the lamp and scale arrangement. The theory, its sensitiveness and working are discussed in detail. A few observations recorded with this instrument are compared with those of the other kinds of hygrometers