Recent X-ray and optical observations of the Perseus cluster indicate that the viscous and conductive dissipation of sound waves is the mechanism responsible for heating the intracluster medium and thus balancing radiative cooling of cluster cores. We discuss this mechanism more generally and show how the specific heating and cooling rates vary with temperature and radius. It appears that the h...

We study the convective motion forced by lateral heating on a liquid layer. The movement is caused by two forces: buoyancy and thermocapillarity on the free surface, which is open to the air. As soon as a temperature gradient is imposed along the liquid layer, the fluid begins to move. When a certain threshold of the temperature difference is attained, this flow destabilizes and oscillations ap...

Temperature sensitivity of the fluorescence intensity of the organic dyes solutions was used for noncontact measurement of the electromagnetic millimeter wave absorption in water. By using two different dyes with opposite temperature effects, local temperature increase in the capillary that is placed inside a rectangular waveguide in which millimeter waves propagate was defined. The application...

An effect of the atmospheric channel on near-ground propagation of acoustic waves is considered. The structure of the amplitude and phase fluctuations of acoustic waves propagating through the turbulent atmosphere near toe ground has been analyzed. The structure of the temperature and wind velocity fields and vertical profiles of the outer scale of atmospheric turbulence have been experimentall...

We review studies of the generation and propagation of nonlinear and shock sound waves in He II the superfluid phase of He , both under the saturated vapor pressure SVP and at elevated pressures. The evolution in shape of second and first sound waves excited by a pulsed heater has been investigated for increasing power W of the heat pulse. It has been found that, by increasing the pressure P fr...

Superfluids support many different types of sound waves. We investigate the relation between the sound waves in a relativistic and a non-relativistic superfluid by using hydrodynamics to calculate the various sound speeds. Then, using a particular holographic scalar gravity realization of a strongly interacting superfluid, we compute first, second and fourth sound speeds as a function of the te...

Simultaneous observations of gravity waves using an Na wind/temperature lidar and a multi-wavelength all-sky nightglow imager were obtained, for the first time, during the ALOHA-93 campaign. A novel investigation of intrinsic wave parameters has been made by combining measurements of the horizontal wave components imaged in four nightglow emissions (height range ~80-100 kin) with Na lidar sound...

–Relativistic effects on the linear and nonlinear properties of electron plasma waves are investigated using the one-dimensional quantum hydrodynamic (QHD) model for a two-component electron-ion dense quantum plasma with an arbitrary temperature and streaming motion. It is shown that the relativistic effects significantly affect the linear and nonlinear properties of electron plasma waves. Depe...

In this proceeding we give a pedagogical explanation of recent work of ours. 1 In this section we show how the velocity of pions, or more generally Goldstone bosons, changes with temperature in a thermal distribution. This in itself is pretty trivial, and familiar from other contexts. For examples, the appropriate analogy to Goldstone bosons in a theory which is relativistically invariant at ze...