Context. Far-UV photons strongly affect the physical and chemical state of molecular gas in the vicinity of young massive stars. Aims. Finding molecular tracers of the presence of FUV radiation fields in the millimeter wavelength domain is desirable, because IR diagnostics (PAHs for instance) are not easily accessible towards high extinction line-of-sights. Furthermore, gas phase diagnostics pr...

A study of the structure and radiation properties of round turbulent carbon monoxide/air diffusion flames is described. Measurements of mean and fluctuating streamwise velocity and mean temperatures, concentrations of major gas species, spectral radiation intensities, and radiant heat fluxes were made. The measurements were used to evaluate predictions based on the laminar flamelet concept and ...

We present the results of axisymmetric time-dependent hydrodynamic calculations of line-driven winds from accretion disks in active galactic nuclei (AGN). We assume the disk is flat, Keplerian, geometrically thin, and optically thick, radiating according to the α-disk prescription. The central engine of the AGN is a source of both ionizing X-rays and wind-driving ultraviolet (UV) photons. To ca...

volatile compounds generated from two types of polymeric laminated films, irradiated by gamma radiation at 8, 10 and 15 kgy, were investigated. activated carbon was used as a dry food simulant to trace the migrating compounds by gas chromatography/mass spectroscopy (gc/ms). the resulting data showed that the polyethylene terephthalate (pet)/polyethylene terephthalate (pet)/linear low density po...

We investigate the e ects of the observed UV background radiation on galaxy formation. Photoionization by UV radiation decreases the cooling rate of the gas in halos, so that objects with only large density contrasts can self-shield against the background radiation, thereby allowing the shielded neutral cores to cool and form stars. In the context of the CDM model, we use the criterion that sel...

Circumstellar disks are exposed to intense ultraviolet (UV) radiation from the young star. In the inner disks, the UV radiation can be enhanced by more than seven orders of magnitude compared with the average interstellar radiation field, resulting in a physical and chemical structure that resembles that of a dense photon-dominated region (PDR). This intense UV field affects the chemistry, the ...

I present results from numerical simulations of gas dynamics outside luminous accretion disks in active galactic nuclei. The gas, gravitationally captured by a super massive black hole, can be driven away by the energy and momentum of the radiation emitted during black hole accretion. Assuming axisymmetry, I study how the mass accretion and outflow rates, and the flow dynamics respond to change...

BACKGROUND The main sources of radiation exposure of all living organisms including humans are natural. In fact, radon and its decay products are the cause of 50% of the total dose that is derived from natural sources. Because of the significant health hazards of radon gas, its levels are widely monitored throughout the world. Accordingly, considerable researches have also been carried out in I...

The aim of the study was to compare the content of ergosterol in different microorganisms (bacteria, yeasts and moulds) isolated from the air as well as in six species of moulds in their different morphological forms-live mycelium, dead mycelium, and spores. Evaluation of the level of mould contamination of the air in various places using culture method and ergosterol determination was also per...

Radiation exposure to astronauts could be a significant obstacle for long duration manned space exploration because of current uncertainties regarding the extent of biological effects. Furthermore, concepts for protective shielding also pose a technically challenging issue due to the nature of cosmic radiation and current mass and power constraints with modern exploration technology. The concer...