We perform linear analysis of thermal instability in a contracting large cloud filled with warm H I gas and investigate the effect of metallicity and radiation flux. When the cloud reaches critical density n f , the cloud fragments into cool, dense condensations because of thermal instability. For a lower metallicity gas cloud, the value of n f is high. Collision between condensations will prod...

We report a combined theoretical and experimental investigation on the near field acoustic levitation (NFAL). In NFAL a disk is levitated at a height much smaller than the acoustic wavelength. The levitation force is induced by the gas squeeze film between the sound radiation surface and the levitated disk. By taking into account the flexural vibration of the sound radiation surface as well as ...

background: radon, an invisible, odorless, heaviest (nine times heavier than air) and radioactive gas is an aberration (the only gas in the long decay chain of heavy metal elements). it is ubiquitously present in dwellings and in the environment. humans receive the greatest radiation dose in their homes. that's where they spend most time - typically 70%, more for small children. recent wor...

An unusual concept for a simple and inexpensive terahertz source is presented: unpeeling adhesive tape. The observed spectrum of this terahertz radiation exhibits a peak at 2 THz and a broader peak at 18 THz. The radiation is not polarized. The mechanism of terahertz radiation is tribocharging of the adhesive tape and subsequent discharge, possibly bremsstrahlung with absorption or energy densi...

Photon–photon scattering, due to photons interacting with virtual electron–positron pairs, is an intriguing deviation from classical electromagnetism predicted by quantum electrodynamics (QED). Apart from being of fundamental interest in itself, collisions between photons are believed to be of importance in the vicinity of magnetars, in the present generation intense lasers, and in intense lase...

Plasma display panels ~PDPs! are a technology for large-area high-brightness flat panel displays. There is considerable interest in improving PDP efficiency by optimizing the cell design, input voltage characteristics, operating conditions and gas mixture. In this article, we report on a two-dimensional computer model for PDPs which has been used to investigate the operation of a coplanar-elect...

In the sixth section of his light quantum paper of 1905, Einstein presented the miraculous argument, as I shall call it. Pointing out an analogy with ideal gases and dilute solutions, he showed that the macroscopic, thermodynamic properties of high-frequency heat radiation carry a distinctive signature of finitely many, spatially localized, independent components and so inferred that it consist...

ABSTARCT The atmospheric gamma radiation level in gas flaring environment has gained the attention of researchers and environmentalists due to its devastating impact both on the climate and the environment. It is important to make a quantitative assessment of the gamma radiation in the gas flaring environment and nearby residential areas. In situ measurements of the gamma radiation were perform...

One of the largest uncertainties in understanding the effect of a background UV field on galaxy formation is the intensity and evolution of the radiation field with redshift. This work attempts to shed light on this issue by computing the quasi-hydrostatic equilibrium states of gas in spherically symmetric dark matter halos (roughly corresponding to dwarf galaxies) as a function of the amplitud...