BACKGROUND Characterization of mechanisms that can reverse residual damage from prior skin exposure to ultraviolet (UV) would be of considerable biological and therapeutic interest. Topical caffeine application to mouse skin that had previously been treated with UV has been shown to inhibit the subsequent development of squamous cell carcinomas. OBJECTIVES We used an established mouse photoda...

We discuss V and R band photometry for 67% of the Sullivan et al. (2000) SA57 ultraviolet-selected galaxy sample. In a sample of 176 UV-selected galaxies, Sullivan et al. (2000) find that 24% have (UV-B) colors too blue for consistency with starburst spectral synthesis models. We propose that these extreme blue, UV excess galaxies are Wolf-Rayet (WR) galaxies, starburst galaxies with strong UV ...

Owing to the conspicuousness of ultraviolet (UV) colour in dark environments, natural selection might have selected UV egg coloration because it would enhance egg detectability by parents in murky nests. Here, we tested this hypothesis by using comparative and experimental approaches. First, we studied variation in egg coloration of 98 species of European passerines measured using UV-visible re...

The distal photoreceptors in the tiered retina of Papilio exhibit different spectral sensitivities. There are at least two types of short-wavelength sensitive receptors: an ultraviolet receptor with a normal spectral shape and a violet receptor with a very narrow spectral bandwidth. Furthermore, a blue receptor, a double-peaked green receptor and a single-peaked green receptor exist. The violet...

An extensive grid of synthetic midand far-ultraviolet spectra for accretion disks in cataclysmic variables has been presented by Wade and Hubeny (1998). In those models, the disk was assumed to be in steady-state, that is Teff(r) is specified completely by the mass MWD and radius RWD of the accreting white dwarf star and the mass transfer rate Ṁ which is constant throughout the disk. In these m...

Ultraviolet disinfection is an attractive tool for treating water and eliminating pathogens with safe and available technology especially in developing countries where waterborne diseases cause the death of thousands of people every year. Even though UV is an easy tool to perform disinfection, concerns over the potential of microorganism reactivation constitute an issue for its development. In ...

The radiation emitted by the sun known as ultraviolet radiation is related to several problems that might affect the human being. Most of times, people are well warned about the effects caused to the skin by the solar radiation overexposure but not about the effects to their eyes. This work aims at developing a real time ultraviolet (UV) index meter and a series of information systems that can ...

We have obtained a far-ultraviolet spectrum of the X-ray binary Hercules X1/HZ Herculis using the Hopkins Ultraviolet Telescope aboard the Astro-1 space shuttle mission in 1990 December. This is the first spectrum of Her X-1 that extends down to the Lyman limit at 912 Å. We observed emission lines of OVIλλ 1031.9, 1037.6, NVλλ 1238.8, 1242.8, and C IVλλ 1548.2, 1550.8, and the far UV continuum ...

background: in general, measurements of solar ultraviolet (uv) radiation are related to horizontal surfaces. while the hu­mans walking and standing outdoors expose to the natural solar uv radiation, their eyes, cheeks, extremities, trunks, or many other anatomical sites are close to vertical plane and random orient to different directions. in this study, we character­ized the diurnal variations...

Single-color illumination of a copper surface by a red or an ultraviolet femtosecond laser pulse yields a threephoton (red) or a two-photon (UV) photoemission process. A multicolor, multiphoton process is generated when the red and the UV pulses overlap both in space and in time on the photocathode. It is shown that this emission process results from the absorption by an electron of one red and...