The purpose of this study was to determine annual occupational exposure to UV radiation by measurement and derive ambient exposure fractions for an entire year that could be applied in the human exposure model. Using polysulphone the daily occupational erythema effective solar ultraviolet radiation exposure at selected body sites of Australia Post mail delivery personnel and physical education teachers were measured over an 18-mo period on a daily basis in the Rockhampton (lat. 23.5 degrees S) region. The daily exposures were summed to estimate an annual exposure for these occupations in this region. For the Australia Post mail delivery personnel, who had very little change to the posture or route during delivery, the annual mean estimates of exposure to erythema effective solar irradiance for the chest, hands, and back were in the range of 192+/-27 kJ m(-2), 388+/-45 kJ m(-2), and 283+/-32 kJ m(-2), respectively. Physical education teachers had varied duties on a day-to-day basis and many changes in their posture and outdoor locations where the exposure occurred. Their annual mean exposure on the vertex (hat), chest, shoulder, thigh, and back were in the range 340+/-71 kJ m(-2), 140+/-28 kJ m(-2), 180+/-40 kJ m(-2), 129+/-24 kJ m(-2), and 212+/-42 kJ m(-2), respectively. The annual exposure range for erythema effective solar irradiance at different body sites during the experimental period was between 120 and 440 kJ m(-2) for the two occupational groups. These exposures greatly exceed the National Health and Medical Research Council occupational standard limit of 30 J m(-2) for daily exposure, which indicates the need for additional protective measures. The ambient exposure was also measured and used to compute ambient exposure fractions for the different body sites over an entire year, which are useful for model calculations on human exposure and assess increase in risk of n on melanoma skin cancer.
Experimental results are presented which reveal the important role played by nonlinear radiation or ponderomotive forces in laser plasma interactions. The existence of these nonlinear forces are clearly revealed by the properties of tenuous helium plasmas generated by focusing of intense laser beams.
The results of an experimental study of electrons produced by multi photon ionization of helium gas by intense 25-psec-duration pulses from a neodymium laser are reported. Electrons with energies up to 300 eV have been observed and both the maximum electron energy and the measured electron-energy spectra are shown to be characteristic of electron acceleration by ponderomotive forces.
We propose that the universe is nonlocal and that the appropriate worldview or paradigm for this understanding is nonlocal realism. Currently the worldview of local realism guides and frames the understanding and interpretations of science. Local realism was the worldview employed by Einstein in his relativity theories, but the principles of this paradigm have operated as the guiding framework for the rest of classic science for more than a century. This paper points to incoherencies in local realism and to the violation of its principles by recent experiments; it suggests that these negative effects have undermined the credibility and legitimacy of this worldview. We offer a more inclusive worldview for the future of science called nonlocal realism. Unlike local realism, the worldview of nonlocal realism encompasses meaning, mind and universal consciousness.
A method of determining the laser intensity necessary for ionization of atomic states is described. Results are presented for ionization of argon states I–V at 10−4 Torr using a short (25 psec)-pulse neodymium laser at intensities up to 4×1016 W cm−2. The results agree with computer calculations of the Keldysh tunneling model in the regime γ⩽1 and with results previously obtained in helium. The electron energy spectra technique employed further verifies the existence of the ponderomotive force.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.