REVIOUS workers have found that in maize the genetic analyses have indicated P an apparent difference between the action of X-ray and ultraviolet on (1) gene mutation, (2) the frequency of reciprocal translocations, (3) the type and frequency of endosperm deficiencies, (4) the ratio of endosperm deficiencies to embryo abortions, and ( 5 ) the types of embryo deficiencies. These contrasts have b...

Introduction: The atmosphere of Mars, unlike that of the Earth, does little to attenuate incoming ultraviolet radiation. Such large amounts of ultraviolet radiation are known not only to sterilize the hardiest of terrestrial organisms within minutes [1], but to chemically alter the soil such that organic molecules in the upper few cm are rapidly destroyed [2]. Thus the survival of any putative ...

A considerable interest is growing worldwide about the photobiological effects of the ultraviolet radiation; in fact, it has been demonstrated that ultraviolet radiation can affect both human health as well as the equilibrium of entire ecosystems. The relative effectiveness of ultraviolet radiation at a particular wavelength in producing a specific biological response is defined by an action sp...

Phototherapy with ultraviolet (UV) radiation of wavelengths between 280 and 320 nm (UVB) is a safe and effective treatment for a variety of diseases. In addition to standard broadband UVB (bUVB), narrowband phototherapy with fluorescent bulbs emitting near monochromatic UV around 311 nm (nUVB) has become an important treatment for diseases such as psoriasis, atopic dermatitis and vitiligo. In a...

The projected large increases in damaging ultraviolet radiation as a result of global emissions of ozonedepleting substances have been forestalled by the success of the Montreal Protocol. New challenges are now arising in relation to climate change. We highlight the complex interactions between the drivers of climate change and those of stratospheric ozone depletion, and the positive and negati...

background bacillus thuringiensis is the most successful biological control agent used in agriculture, forestry and mosquito control. however, the insecticidal activity of the b. thuringiensis formulation is not very stable and rapidly loses its biological activity under field conditions, due to the ultraviolet radiation in sunlight. melanin is known to absorb radiation therefore photo protecti...

Combined disinfection with UV radiation and sodium hypochlorite was applied in disinfection the effluent after secondary treatment of hospital sewage. The inactivation effect of different combination modes and sequences of UV and sodium hypochlorite was studied. The contrast experiments of disinfection effect and the levels of residual chlorine were conducted by adding different dosage of sodiu...

A sufficient dose of ultraviolet light (2,0537 A) inactivates most microorganisms. Exposure of inactivated cells to suitable visible light results in the recovery of a large portion of the cells from their otherwise fatal ultraviolet-induced injury. The discovery of light-induced recovery (Kelner, 1949) and its confirmation for bacteriophage by Dulbecco (1949) gives us fresh hope for solving th...