Most gases and vapours with a bipolar molecular structure absorb infrared energy. If such a gas is interposed between an object emitting infrared radiation and a thermocamera the gas will absorb some of the infrared radiation and thus cast a shadow on the thermocamera picture. In this assay it is possible to visualise the gas. This method had been used to study pollution with anaesthetic gases ...

Radiation produced by low-voltage discharge in a gas containing deuterium was measured using a Geiger counter located within the apparatus. This radiation was found to consist of energetic particles that were produced only when the voltage was above a critical value. In addition, the emission was very sensitive to the presence of oxygen in the gas. In the presence of the required conditions, em...

We perform radiation hydrodynamics simulations on the evolution of galactic gas disks irradiated by ultraviolet radiation background. We find gas disks with NH & 10 cm exposed to ultraviolet radiation at a level of I21 = 1 can be self-shielded from photoheating, whereas the disk with NH . 10 cm cannot. We also find that the unshielded disks keep smooth density distribution without any sign of f...

We calculate the evolution of linear density and temperature perturbations in a universe with dark matter, baryons, and radiation, from cosmic recombination until the epoch of the first galaxies. In addition to gravity, the perturbations are effected by electron scattering with the radiation, by radiation pressure, and by gas pressure. We include the effect of spatial fluctuations in the baryon...

all living organisms are exposed to ionizing radiation comprising cosmic rays coming from outer space, terrestrial nuclides occurring in the earth’s crust, building materials, air, water and foods and in the human body itself. the exposures are constant and uniform for all individuals everywhere including the dose from ingestion of 40k in food. cosmic rays are, more intense at higher altitudes,...

The vertical structure of black hole accretion disks in which radiation dominates the total pressure is investigated using a three-dimensional radiation-MHD calculation. The domain is a small patch of disk centered 100 Schwarzschild radii from a black hole of 10 M⊙, and the stratified shearing-box approximation is used. Magneto-rotational instability converts gravitational energy to turbulent m...

background: high level radiation areas have been recognized on various parts of the earth. mahallat hot spring region is one of these areas. study of exposure in these areas can be helpful in investigating the effects of ionizing radiation. internal and external exposure to the staff was studied. materials and methods: used materials and instruments include: rss-112 ionizing chamber for environ...

It is well-known that a charged particle moving with constant velocity in vacuum does not radiate. In a medium the situation can be different. If the so called Cherenkov condition is satisfied, i.e. the particle velocity exceeds the phase speed in the medium, the particle will radiate. We show that a charge moving with a constant velocity in a gas of photons emits Cherenkov radiation, even in t...

The Orion Nebula is the defining galactic HII Region, and has been well studied over a broad range of wavelengths. Many of its properties are well established. The gas-phase metallicity is roughly 2/3 of solar, close to that of the star cluster. There is no evidence that grains are destroyed anywhere in the Orion environment; refractory elements such as Ca and Fe remain heavily depleted. If the...

We present the first results from two-dimensional simulations of radiatively-efficient accretion of metal-free gas onto intermediate-mass black holes. We fix the shape of the spectral energy distribution of the radiation produced near the event horizon and study the structure of the irradiated low-angular-momentum accretion flow over three orders of magnitude in radius from the black hole, 1014...