Science.gov

Sample records for diffuse uv radiation

  1. Solar UV-B in tropical forest gaps: Analysis using direct and diffuse radiation

    SciTech Connect

    Flint, S.D.; Caldwell, M.M.

    1995-06-01

    Experiments with natural levels of solar ultraviolet-B radiation (UV-B) have recently shown inhibition of the growth of some tropical forest tree seedlings. A knowledge of forest radiation environments is needed to help assess UV-B effects in natural situations. Although forest canopies strongly attenuate solar radiation, treefall gaps provide a very different radiation environment. We simultaneously measured both UV-B and photosynthetically active radiation (PAR) in forest gaps on Barro Colorado Island, Panama. Outside the forest, UV-B is predominately diffuse even under clear sky conditions. In sunflecks of small forest gaps, most of the UV-B was in the direct beam component. Compared to conditions outside the forest, the UV-B in these sunflecks was low relative to PAR. Shaded portions of the gap, in contrast, had proportionately high levels of UV-B relative to PAR. There are indications in the literature that relatively low UV-B levels may be effective under low PFD. Seasonal trends of PAR and UV-B in different locations in gaps can be inferred from hemispherical canopy photographs.

  2. Estimating the UV diffuse fraction of solar radiation under partly cloudy skies

    NASA Astrophysics Data System (ADS)

    Grant, Richard H.; Gao, Wei

    2002-01-01

    A major limitation in predicting the ultraviolet-B (UVB) irradiance on humans, plant leaves and flowers and aquatic organisms is the difficulty in determining the UVB under partly cloudy sky conditions. This study analyzes the UV diffuse fractions under partly cloudy and clear conditions for nine locations in the USA over a period of 1997 through 1999. Radiation measurements, made as part of the United States Department of Agriculture UVB Monitoring Program using multi-filter rotating shadow band radiometers, were paired with cloud cover and other atmospheric measurements made with National Weather Service Automated Surface Observation Systems within 30 km of the radiation measurement location to evaluate the accuracy of using a relatively simple model to describe the diffuse fraction of UV radiation under partly-cloudy skies. The diffuse fraction was modeled as the summation of clear and overcast sky diffuse fractions, weighted by the probability of the sun's direct beam being obstructed or not for a given cloud cover fraction. For the nine locations evaluated, the model had a mean bias error (MBE) of 0.0037 and a root mean squared error (RMSE) of 0.0361. Simplifying the model by assuming a diffuse fraction of 1 for the overcast sky resulted in a slightly higher error (MBE error of -0.0045 and an RMSE of 0.0387). Model errors were greatest for low solar zenith angles and high cloud fractions. The greatest error, associated with overcast sky conditions, appeared to be a result of scattering off the clouds during the period of time where the sun's beam was unobstructed. Error analysis also showed that the diffuse fraction of partly cloudy skies when the sun's beam was not obstructed is well approximated by the clear sky condition to within approximately 0.1, supporting the use of aerosol optical thickness estimates by Langley plot under partly cloudy skies.

  3. Diffuse radiation

    NASA Technical Reports Server (NTRS)

    1981-01-01

    A diffuse celestial radiation which is isotropic at least on a course scale were measured from the soft X-ray region to about 150 MeV, at which energy the intensity falls below that of the galactic emission for most galactic latitudes. The spectral shape, the intensity, and the established degree of isotropy of this diffuse radiation already place severe constraints on the possible explanations for this radiation. Among the extragalactic theories, the more promising explanations of the isotropic diffuse emission appear to be radiation from exceptional galaxies from matter antimatter annihilation at the boundaries of superclusters of galaxies of matter and antimatter in baryon symmetric big bang models. Other possible sources for extragalactic diffuse gamma radiation are discussed and include normal galaxies, clusters of galaxies, primordial cosmic rays interacting with intergalactic matter, primordial black holes, and cosmic ray leakage from galaxies.

  4. Repetitively pulsed UV radiation source based on a run-away electron preionised diffuse discharge in nitrogen

    NASA Astrophysics Data System (ADS)

    Baksht, E. Kh; Burachenko, A. G.; Lomaev, M. I.; Panchenko, A. N.; Tarasenko, V. F.

    2015-04-01

    An extended repetitively pulsed source of spontaneous UV radiation is fabricated, which may also be used for producing laser radiation. Voltage pulses with an incident wave amplitude of up to 30 kV, a half-amplitude duration of ~4 ns and a rise time of ~2.5 ns are applied to a gap with a nonuniform electric field. For an excitation region length of 35 cm and a nitrogen pressure of 30 - 760 Torr, a diffusive discharge up to a pulse repetition rate of 2 kHz is produced without using an additional system for gap preionisation. An investigation is made of the plasma of the run-away electron preionised diffuse discharge. Using a CCD camera it is found that the dense diffused plasma fills the gap in a time shorter than 1 ns. X-ray radiation is recorded from behind the foil anode throughout the pressure range under study; a supershort avalanche electron beam is recorded by the collector electrode at pressures below 100 Torr.

  5. The far-UV diffuse background revisited

    NASA Astrophysics Data System (ADS)

    Perault, M.; Lequeux, J.; Hanus, M.; Joubert, M.

    1991-06-01

    A new reduction is presented of the high-galactic latitude whole-sky survey obtained with the D2B-AURA satellite at 1690 A. This reduction differs in several ways from the previously published one (Joubert et al., 1983), especially by a correction for gain variations with time which had remained unnoticed in the first reduction. The existence of a correlation between the UV sky background and gas and dust is confirmed. There are no clear local excesses at large scale of UV radiation with respect to the mean relations UV versus gas or dust column densities.

  6. Personal monitoring of UV radiation

    NASA Astrophysics Data System (ADS)

    Barth, Joachim; Knuschke, Peter

    1994-06-01

    Personal monitoring of till-radiation (UVR) is important fo find out both overexposure and underexposure to UVR. At present polysulfone films seem to be most suitable for these purposes. They allow a reliable measurement of till-exposure to wavelengths between 250 and 330 nm if a number of influencing factors is respected. These are described in detail in a technical report of the Commission Internationale de L'Eclairage (CIE). Own investigations with polysulphone films have shown that these polymers can help as well to detect an overexposure to UVR at workplaces as an UVR-deficiency of people living in an old peoples home. It could be demonstrated that this till-deficiency well correlates to the deficiency of serum 25(OH)D3 levels of these people. Furthermore after optimization of a new phototherapeutic equipment in uniformity of UV-exposure round patients body by polysulphone film dosimeters it got useable in therapy.

  7. UV RADIATION MEASUREMENTS/ATMOSPHERIC CHARACTERIZATION

    EPA Science Inventory

    Because exposure to ultraviolet (UV) radiation is an ecosystem stressor and poses a human health risk, the National Exposure Research Laboratory (NERL) has undertaken a research program to measure the intensity of UV-B radiation at various locations throughout the U.S. In Septem...

  8. Diffuse gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1977-01-01

    An examination of the intensity, energy spectrum, and spatial distribution of the diffuse gamma-radiation observed by SAS-2 satellite away from the galactic plane in the energy range above 35 MeV has shown that it consists of two components. One component is generally correlated with galactic latitudes, the atomic hydrogen column density was deduced from 21 cm measurements, and the continuum radio emission, believed to be synchrotron emission. It has an energy spectrum similar to that in the plane and joins smoothly to the intense radiation from the plane. It is therefore presumed to be of galactic origin. The other component is apparently isotropic, at least on a coarse scale, and has a steep energy spectrum. No evidence is found for a cosmic ray halo surrounding the galaxy in the shape of a sphere or oblate spheroid with galactic dimensions. Constraints for a halo model with significantly larger dimensions are set on the basis of an upper limit to the gamma-ray anisotropy.

  9. Sources of Error in UV Radiation Measurements

    PubMed Central

    Larason, Thomas C.; Cromer, Christopher L.

    2001-01-01

    Increasing commercial, scientific, and technical applications involving ultraviolet (UV) radiation have led to the demand for improved understanding of the performance of instrumentation used to measure this radiation. There has been an effort by manufacturers of UV measuring devices (meters) to produce simple, optically filtered sensor systems to accomplish the varied measurement needs. We address common sources of measurement errors using these meters. The uncertainty in the calibration of the instrument depends on the response of the UV meter to the spectrum of the sources used and its similarity to the spectrum of the quantity to be measured. In addition, large errors can occur due to out-of-band, non-linear, and non-ideal geometric or spatial response of the UV meters. Finally, in many applications, how well the response of the UV meter approximates the presumed action spectrum needs to be understood for optimal use of the meters.

  10. UV extinction and IR emission in diffuse H2 regions

    NASA Technical Reports Server (NTRS)

    Aannestad, Per A.

    1994-01-01

    HII regions occupy a unique position in our understanding of the physical relationships between stars, the interstellar medium, and galactic structure. Observations show a complex interaction between a newly formed hot star and its surroundings. In particular, the ultraviolet radiation from the stars modifies the pre-existing dust, which again affects both the amount of ionizing radiation absorbed by the gas, and the infrared spectrum emitted by the heated dust. The aim of this project was to use UV and far-UV observations to gain information on the nebular dust, and to use this dust to model the far-IR emission, for a consistent picture of a few selected diffuse HII regions. Using archival data from the IUE and Voyager data banks and computed model atmospheres, we have deduced extinction curves for early-types stars. The requisite spectral resolution turned out to be a major task. We have successfully modelled these curves in terms of a multi-component, multi-size distribution of dust grains, and interpret the differences in the curves as primarily due to the presence or non-presence of intermediate size grains (0.01 to 0.04 micron). Much smaller (0.005 micron) grains must also be present. Finally, we have made calculations of the temperature fluctuations and the corresponding infra-red emission in such small grains.

  11. Effect of AO/UV/RD exposure on spaceborne diffusers: a comparative experiment.

    PubMed

    Zhao, Minjie; Si, Fuqi; Liu, Cheng; Lu, Yihuai; Wang, Yu; Wang, Shimei; Zeng, Yi; Jiang, Yu; Zhou, Haijin; Liu, Wenqing

    2015-11-01

    The environmental measuring instrument (EMI) is a nadir-viewing wide-field imaging spectrometer, which adopts spaceborne diffusers in in-flight calibration systems, including an aluminum diffuser and a quartz volume diffuser. Spaceborne diffusers, are the key components of in-flight calibration systems, and are used to introduce sunlight into the EMI. Hemispheric reflectance and bidirectional reflectance distribution function were experimentally measured to analyze spaceborne diffuser performance. Radiation exposure experiments on atomic oxygen, UV, and radiation dose of the spaceborne diffusers were performed at ground level because the EMI works in low Earth orbit space environments. Effects of radiation exposure on spaceborne diffusers were discussed in detail. Protective methods were introduced to reduce the effects of the space environment, and an in-orbit monitoring method was also proposed. PMID:26560568

  12. Effects of UV radiation on phytoplankton

    NASA Astrophysics Data System (ADS)

    Smith, Raymond C.; Cullen, John J.

    1995-07-01

    It is now widely documented that reduced ozone will result in increased levels of ultraviolet (UV) radiation, especially UV-B (280-320nm), incident at the surface of the earth [Watson, 1988; Anderson et al., 1991; Schoeberl and Hartmann, 1991; Frederick and Alberts, 1991; WMO, 1991; Madronich, 1993; Kerr and McElroy, 1993], and there is considerable and increasing evidence that these higher levels of UV-B radiation may be detrimental to various forms of marine life in the upper layers of the ocean. With respect to aquatic ecosystems, we also know that this biologically- damaging mid-ultraviolet radiation can penetrate to ecologically- significant depths in marine and freshwater systems [Jerlov, 1950; Lenoble, 1956; Smith and Baker, 1979; Smith and Baker, 1980; Smith and Baker, 1981; Kirk et al., 1994]. This knowledge, plus the dramatic decline in stratospheric ozone over the Antarctic continent each spring, now known to be caused by anthropogenically released chemicals [Solomon, 1990; Booth et al., 1994], has resulted in increased UV-environmental research and a number of summary reports. The United Nations Environmental Program (UNEP) has provided recent updates with respect to the effects of ozone depletion on aquatic ecosystems (Hader, Worrest, Kumar in UNEP 1989, 1991, Hader, Worrest, Kumar and Smith UNEP 1994) and the Scientific Committee on Problems of the Environment (SCOPE) has provided [SCOPE, 1992] a summary of the effects of increased UV radiation on biological systems. SCOPE has also reported [SCOPE, 1993] on the effects of increased UV on the biosphere. In addition, several books have recently been published reviewing various aspects of environmental UV photobiology [Young et al., 1993], UV effects on humans, animals and plants [Tevini, 1993], the biological effects of UV radiation in Antarctica [Weiler and Penhale, 1994], and UV research in freshwater ecosystems [Williamson and Zagarese, 1994]. Several other reviews are relevant [NAS, 1984; Caldwell

  13. A method for optimizing the cosine response of solar UV diffusers

    NASA Astrophysics Data System (ADS)

    Pulli, Tomi; Kärhä, Petri; Ikonen, Erkki

    2013-07-01

    Instruments measuring global solar ultraviolet (UV) irradiance at the surface of the Earth need to collect radiation from the entire hemisphere. Entrance optics with angular response as close as possible to the ideal cosine response are necessary to perform these measurements accurately. Typically, the cosine response is obtained using a transmitting diffuser. We have developed an efficient method based on a Monte Carlo algorithm to simulate radiation transport in the solar UV diffuser assembly. The algorithm takes into account propagation, absorption, and scattering of the radiation inside the diffuser material. The effects of the inner sidewalls of the diffuser housing, the shadow ring, and the protective weather dome are also accounted for. The software implementation of the algorithm is highly optimized: a simulation of 109 photons takes approximately 10 to 15 min to complete on a typical high-end PC. The results of the simulations agree well with the measured angular responses, indicating that the algorithm can be used to guide the diffuser design process. Cost savings can be obtained when simulations are carried out before diffuser fabrication as compared to a purely trial-and-error-based diffuser optimization. The algorithm was used to optimize two types of detectors, one with a planar diffuser and the other with a spherically shaped diffuser. The integrated cosine errors—which indicate the relative measurement error caused by the nonideal angular response under isotropic sky radiance—of these two detectors were calculated to be f2=1.4% and 0.66%, respectively.

  14. DIFFUSE MOLECULAR CLOUD DENSITIES FROM UV MEASUREMENTS OF CO ABSORPTION

    SciTech Connect

    Goldsmith, Paul F.

    2013-09-10

    We use UV measurements of interstellar CO toward nearby stars to calculate the density in the diffuse molecular clouds containing the molecules responsible for the observed absorption. Chemical models and recent calculations of the excitation rate coefficients indicate that the regions in which CO is found have hydrogen predominantly in molecular form and that collisional excitation is by collisions with H{sub 2} molecules. We carry out statistical equilibrium calculations using CO-H{sub 2} collision rates to solve for the H{sub 2} density in the observed sources without including effects of radiative trapping. We have assumed kinetic temperatures of 50 K and 100 K, finding this choice to make relatively little difference to the lowest transition. For the sources having T{sup ex}{sub 10} only for which we could determine upper and lower density limits, we find (n(H{sub 2})) = 49 cm{sup -3}. While we can find a consistent density range for a good fraction of the sources having either two or three values of the excitation temperature, there is a suggestion that the higher-J transitions are sampling clouds or regions within diffuse molecular cloud material that have higher densities than the material sampled by the J = 1-0 transition. The assumed kinetic temperature and derived H{sub 2} density are anticorrelated when the J = 2-1 transition data, the J = 3-2 transition data, or both are included. For sources with either two or three values of the excitation temperature, we find average values of the midpoint of the density range that is consistent with all of the observations equal to 68 cm{sup -3} for T{sup k} = 100 K and 92 cm{sup -3} for T{sup k} = 50 K. The data for this set of sources imply that diffuse molecular clouds are characterized by an average thermal pressure between 4600 and 6800 K cm{sup -3}.

  15. Skin cancer and solar UV radiation.

    PubMed

    de Gruijl, F R

    1999-12-01

    Ultraviolet (UV) radiation in sunlight is the most prominent and ubiquitous physical carcinogen in our natural environment. It is highly genotoxic but does not penetrate the body any deeper than the skin. Like all organisms regularly exposed to sunlight, the human skin is extremely well adapted to continuous UV stress. Well-pigmented skin is clearly better protected than white Caucasian skin. The sun-seeking habits of white Caucasians in developed countries are likely to have contributed strongly to the increase in skin cancer observed over the last century. Skin cancer is by far the most common type of cancer in the U.S.A. and Australia, which appears to be the result of an 'unnatural displacement' of people with sun-sensitive skin to sub-tropical regions. Although campaigns have been successful in informing people about the risks of sun exposure, general attitudes and behaviour do not yet appear to have changed to the extent that trends in skin cancer morbidity and the corresponding burden on public healthcare will be reversed. The relationship between skin cancer and regular sun exposure was suspected by physicians in the late 19th century, and subsequently substantiated in animal experiments in the early part of the 20th century. UV radiation was found to be highly genotoxic, and DNA repair proved to be crucial in fending off detrimental effects such as mutagenesis and cell death. In fact, around 1940 it was shown that the wavelength dependence of mutagenicity paralleled the UV absorption by DNA. In the 1970s research on UV carcinogenesis received a new impetus from the arising concern about a possible future depletion of the stratospheric ozone layer: the resulting increases in ambient UV loads were expected to raise skin cancer incidences. Epidemiological studies in the last decades of the 20th century have greatly refined our knowledge on the aetiology of skin cancers. Analyses of gene mutations in skin carcinomas have identified UV radiation as the cause

  16. MEDICAL AND ENVIRONMENTAL EFFECTS OF UV RADIATION.

    SciTech Connect

    SUTHERLAND, B.M.

    2001-07-26

    Organisms living on the earth are exposed to solar radiation, including its ultraviolet (UV) components (for general reviews, the reader is referred to Smith [1] and Young et al. [2]). UV wavelength regions present in sunlight are frequently designated as UVB (290-320 nm) and UVA (320-400 nm). In today's solar spectrum, UVA is the principal UV component, with UVB present at much lower levels. Ozone depletion will increase the levels of UVB reaching the biosphere, but the levels of UVA will not be changed significantly [3]. Because of the high efficiency of UVB in producing damage in biological organisms in the laboratory experiments, it has sometimes been assumed that UVA has little or no adverse biological effects. However, accumulating data [4, 5], including action spectra (efficiency of biological damage as a function of wavelength of radiation; see Section 5) for DNA damage in alfalfa seedlings [6], in human skin [7], and for a variety of plant damages (Caldwell, this volume) indicate that UVA can induce damage in DNA in higher organisms. Thus, understanding the differential effects of UVA and UVB wavebands is essential for estimating the biological consequences of stratospheric ozone depletion.

  17. Modelling of ground-level UV radiation

    NASA Astrophysics Data System (ADS)

    Koepke, P.; Schwander, H.; Thomalla, E.

    1996-06-01

    A number of modifications were made on the STAR radiation transmission model for greater ease of use while keeping its fault liability low. The improvements concern the entire aerosol description function of the model, the option of radiation calculation for different receiver geometries, the option of switching off temperature-dependent ozone absorption, and simplications of the STAR menu. The assets of using STAR are documented in the studies on the accuracy of the radiation transmission model. One of these studies gives a detailed comparison of the present model with a simple radiation model which reveals the limitations of approximation models. The other examines the error margin of radiation transmission models as a function of the input parameters available. It was found here that errors can be expected to range between 5 and 15% depending on the quality of the input data sets. A comparative study on the values obtained by measurement and through the model proved this judgement correct, the relative errors lying within the predicted range. Attached to this final report is a comprehensive sensitivity study which quantifies the action of various atmospheric parameters relevant to UV radiation, thus contributing to an elucidation of the process.

  18. Temporal variation of optimal UV exposure time over Korea: risks and benefits of surface UV radiation

    NASA Astrophysics Data System (ADS)

    Lee, Y. G.; Koo, J. H.

    2015-12-01

    Solar UV radiation in a wavelength range between 280 to 400 nm has both positive and negative influences on human body. Surface UV radiation is the main natural source of vitamin D, providing the promotion of bone and musculoskeletal health and reducing the risk of a number of cancers and other medical conditions. However, overexposure to surface UV radiation is significantly related with the majority of skin cancer, in addition other negative health effects such as sunburn, skin aging, and some forms of eye cataracts. Therefore, it is important to estimate the optimal UV exposure time, representing a balance between reducing negative health effects and maximizing sufficient vitamin D production. Previous studies calculated erythemal UV and vitamin-D UV from the measured and modelled spectral irradiances, respectively, by weighting CIE Erythema and Vitamin D3 generation functions (Kazantzidis et al., 2009; Fioletov et al., 2010). In particular, McKenzie et al. (2009) suggested the algorithm to estimate vitamin-D production UV from erythemal UV (or UV index) and determined the optimum conditions of UV exposure based on skin type Ⅱ according to the Fitzpatrick (1988). Recently, there are various demands for risks and benefits of surface UV radiation on public health over Korea, thus it is necessary to estimate optimal UV exposure time suitable to skin type of East Asians. This study examined the relationship between erythemally weighted UV (UVEry) and vitamin D weighted UV (UVVitD) over Korea during 2004-2012. The temporal variations of the ratio (UVVitD/UVEry) were also analyzed and the ratio as a function of UV index was applied in estimating the optimal UV exposure time. In summer with high surface UV radiation, short exposure time leaded to sufficient vitamin D and erythema and vice versa in winter. Thus, the balancing time in winter was enough to maximize UV benefits and minimize UV risks.

  19. Skyglow effects in UV and visible spectra: Radiative fluxes

    NASA Astrophysics Data System (ADS)

    Kocifaj, Miroslav; Solano Lamphar, Hector Antonio

    2013-09-01

    Several studies have tried to understand the mechanisms and effects of radiative transfer under different night-sky conditions. However, most of these studies are limited to the various effects of visible spectra. Nevertheless, the invisible parts of the electromagnetic spectrum can pose a more profound threat to nature. One visible threat is from what is popularly termed skyglow. Such skyglow is caused by injudiciously situated or designed artificial night lighting systems which degrade desired sky viewing. Therefore, since lamp emissions are not limited to visible electromagnetic spectra, it is necessary to consider the complete spectrum of such lamps in order to understand the physical behaviour of diffuse radiation at terrain level. In this paper, the downward diffuse radiative flux is computed in a two-stream approximation and obtained ultraviolet spectral radiative fluxes are inter-related with luminous fluxes. Such a method then permits an estimate of ultraviolet radiation if the traditionally measured illuminance on a horizontal plane is available. The utility of such a comparison of two spectral bands is shown, using the different lamp types employed in street lighting. The data demonstrate that it is insufficient to specify lamp type and its visible flux production independently of each other. Also the UV emissions have to be treated by modellers and environmental scientists because some light sources can be fairly important pollutants in the near ultraviolet. Such light sources can affect both the living organisms and ambient environment.

  20. Diffuse Cosmic Infrared Background Radiation

    NASA Technical Reports Server (NTRS)

    Dwek, Eli

    2002-01-01

    The diffuse cosmic infrared background (CIB) consists of the cumulative radiant energy released in the processes of structure formation that have occurred since the decoupling of matter and radiation following the Big Bang. In this lecture I will review the observational data that provided the first detections and limits on the CIB, and the theoretical studies explaining the origin of this background. Finally, I will also discuss the relevance of this background to the universe as seen in high energy gamma-rays.

  1. PLANT PROTECTIVE RESPONSE TO ENHANCED UV-B RADIATION UNDER FIELD CONDITIONS: LEAF OPTICAL PROPERTIES AND PHOTOSYNTHESIS

    EPA Science Inventory

    Plants of Vicia faba were grown in the field during early to midsummer while receiving two levels of supplemental UV-B radiation. Light-saturated photosynthesis and stomatal diffusive conductance of intact leaves did not show any indications of UV-radiation damage. Supplemental U...

  2. Spatial interpolation of biologically effective UV radiation over Poland

    NASA Astrophysics Data System (ADS)

    Walawender, J.; Ustrnul, Z.

    2010-09-01

    The ultraviolet(UV) radiation plays an important role in the Earth-Atmosphere System. It has a positive influence on both human health and natural environment but it may also be very harmful if UV exposure exceeds "safe" limits. For that reason knowledge about spatial distribution of biologically effective UV doses seems to be crucial in minimization or complete elimination of the negative UV effects. The main purpose of this study is to find the most appropriate interpolation method in order to create reliable maps of the biologically effective UV radiation over Poland. As the broadband UV measurement network in Poland is very sparse, erythemaly weighted UV radiation data reconstructed from homogeneous global solar radiation records were used. UV reconstruction model was developed in Centre of Aerology (Institute of Meteorology and Water Management) within COST Action 726 - ‘Long term changes and climatology of UV radiation over Europe'. The model made it possible to reconstruct daily erythemal UV doses for 21 solar radiation measurement stations in the period 1985 - 2008. Mapping methodology included the following processing steps: exploratory spatial data analysis, verification of additional variables, selection and parameterization of interpolation model, accuracy assessment and cartographic visualization. Several different stochastic and deterministic interpolation methods along with various empirical semivariogram models were tested. Multiple regression analysis was performed in order to examine statistical relationship between UV radiation and additional environmental variables such as: elevation, latitude, stratospheric ozone content and cloud cover. The data were integrated, processed and visualized within GIS environment.

  3. UV RADIATION EFFECTS ON MICROBES AND MICROBIAL PROCESSES

    EPA Science Inventory

    The ultraviolet (UV) region of solar radiation is defined as wavelengths in the range of 200 to 400 nm. In contrast to visible radiation (400 - 800 nm), which has a well-defined role as the energy source for most of the Earth's primary production, the effects of UV radiation on b...

  4. Evaluation of the impact of atmospheric ozone and aerosols on the horizontal global/diffuse UV Index at Livorno (Italy)

    NASA Astrophysics Data System (ADS)

    Scaglione, Daniele; Giulietti, Danilo; Morelli, Marco

    2016-08-01

    A study was conducted at Livorno (Italy) to evaluate the impact of atmospheric aerosols and ozone on the solar UV radiation and its diffuse component at ground in clear sky conditions. Solar UV radiation has been quantified in terms of UV Index (UVI), following the ISO 17166:1999/CIE S007/E-1998 international standard. UVI has been calculated by exploiting the libRadtran radiative transfer modelling software as a function of both the Aerosols Optical Depth (AOD) and the Total Ozone Column (TOC). In particular AOD and TOC values have been remotely sensed by the Ozone Monitoring Instrument (OMI) on board the NASA's EOS (Earth Observing System) satellites constellation. An experimental confirmation was also obtained by exploiting global UVI ground-based measurements from the 26/9/14 to 12/8/15 and diffuse UVI ground-based measurements from the 17/5/15 to 12/8/15. For every considered value of Solar Zenith Angle (SZA) and atmospheric condition, estimates and measurements confirm that the diffuse component contributes for more than 50% on the global UV radiation. Therefore an exposure of human skin also to diffuse solar UV radiation can be potentially harmful for health and need to be accurately monitored, e.g. by exploiting innovative applications such as a mobile app with a satellite-based UV dosimeter that has been developed. Global and diffuse UVI variations due to the atmosphere are primarily caused by the TOC variations (typically cyclic): the maximum TOC variation detected by OMI in the area under study leads to a corresponding variation in global and diffuse UVI of about 50%. Aerosols in the area concerned, mainly of maritime nature, have instead weaker effects causing a maximum variation of the global and diffuse UVI respectively of 9% and 35% with an SZA of 20° and respectively of 13% and 10% with an SZA of 60°.

  5. Life under solar UV radiation in aquatic organisms

    NASA Astrophysics Data System (ADS)

    Sinha, R. P.; Häder, D.-P.

    Aquatic photosynthetic organisms are exposed to solar ultraviolet (UV) radiation while they harvest longer wavelength radiation for energetic reasons. Solar UV-B radiation (280 - 315 nm) affects motility and orientation in motile organisms and impairs photosynthesis in cyanobacteria, phytoplankton and macroalgae as measured by monitoring oxygen production or pulse amplitude modulated fluorescence analysis. Upon moderate UV stress most organisms respond by photoinhibition which is an active downregulation of the photosynthetic electron transport in photosystem II by degradation of UV-damaged D1 protein. Photoinhibition is readily reversible during recovery in shaded conditions. Excessive UV stress causes photodamage which is not easily reversible. Another major target is the DNA where UV-B mainly induces thymine dimers. Cyanobacteria, phytoplankton and macroalgae produce scytonemin, mycosporine-like amino acids and other UV-absorbing substances to protect themselves from short wavelength solar radiation.

  6. Exposure to UV radiation and human health

    NASA Astrophysics Data System (ADS)

    Kimlin, Michael G.

    2005-08-01

    This paper will overview the significant issues facing researchers in relating the impact of exposure to sunlight and human health. Exposure to solar ultraviolet radiation is the major causative factor in most sun-related skin and eye disorders, however, very little is known quantitatively about human UV exposures. Interestingly, human exposure to sunlight also has a nutritional impact, namely the development of pre-Vitamin D, which is an important nutrient in bone health. New research suggest that low vitamin D status may be a causative factor in the development of selective types of cancer and autoimminue diseases, as well as a contributing factor in bone health. The 'health duality' aspect of sunlight exposure is an interesting and controversial topic that is a research focus of Kimlin's research group.

  7. Covalent dimerization of ribulose bisphosphate carboxylase subunits by UV radiation.

    PubMed

    Ferreira, R M; Franco, E; Teixeira, A R

    1996-08-15

    The effect of UV radiation (UV-A, UV-B and UV-C) on ribulose bisphosphate carboxylase from a variety of plant species was examined. The exposition of plant leaves or the pure enzyme to UV radiation produced a UV-dependent accumulation of a +5 kDa polypeptide (P65). Different approaches were utilized to elucidate the origin and structure of P65: electrophoretic and fluorographic analyses of 35S-labelled ribulose bisphosphate carboxylase exposed to UV radiation and immunological experiments using antibodies specific for P65, for the large and small subunits of ribulose bisphosphate carboxylase and for high-molecular-mass aggregates of the enzyme. These studies revealed that P65 is a dimer, formed by the covalent, non-disulphide linkage of one small subunit with one large subunit of ribulose bisphosphate carboxylase. For short periods of time (< 1 h), the amount of P65 formed increased with the duration of the exposure to the UV radiation and with the energy of the radiation applied. Prolonged exposure to UV radiation (1-6 h) resulted in the formation of high-molecular-mass aggregates of ribulose bisphosphate carboxylase. Formation of P65 was shown to depend on the native state of the protein, was stimulated by inhibitors of enzyme activity, and was inhibited by activators of enzyme activity. A UV-independent accumulation of P65 was also achieved by the in vitro incubation of plant crude extracts. However, the UV-dependent and the UV-independent formation of P65 seemed to occur by distinct molecular mechanisms. The UV-dependent accumulation of P65 was immunologically detected in all species examined, including Lemna minor, Arum italicum, Brassica oleracea, Triticum aestivum, Zea mays, Pisum sativum and Phaseolus vulgaris, suggesting that it may constitute a universal response to UV radiation, common to all photo-synthetic tissues. PMID:8761476

  8. Recent studies on UV radiation in Brazil

    NASA Astrophysics Data System (ADS)

    Correa, M. P.; Ceballos, J. C.; Moregula, A.; Okuno, E.; Fausto, A.; Mol, A.; Santos, J. C.

    2009-04-01

    This presentation shows a summary of UV index measurements performed in the last years in Southeastern (SE) and Northeastern (NE) Brazilian regions. Brazil has an area of 8.5 million km2 distributed between latitudes 5˚ N and 35˚ S and longitudes 5˚ W and 75˚ W. SE is the most important economic pole of South America and the NE coast is an important tourist region. This large area has a great diversity of climatic, atmospheric and geographical conditions in addition to very diverse social and cultural habits. Non-melanoma skin cancer (NMSC) is an epidemiological health problem with more than 120,000 new cases each year. The most of these cases are found in the South and Southeast regions, with about 70 new NMSC per 100,000 inhabitants. Solar Light UV501 biometers are installed in the SE cities of São Paulo (23.6˚ S, 46.7˚ W, 865 m ASL), Itajubá/Minas Gerais (22.4˚ S; 45.5˚ W, 846 m ASL) and the NE city of Ilhéus/Bahia (14.8˚ S; 39.3˚ W; 54 m ASL). First measurements began in 2005 in São Paulo city, while Itajubá and Ilhéus have regular measurements from the beginning of 2008. Other studies related to the UV radiation modeling and interactions with atmosphere components, as ozone, aerosols and clouds, have also been performed. For example: a) UVI modelling calculations performed by a multiple-scattering spectral models; b) studies on the aerosol radiative properties based on satellite (MODIS/Terra-Aqua) and ground-based (Aeronet) observation; c) ozone content variability from satellite (OMI/Aura) and ground-based (Microtops ozonometer) measurements; d) behavioral profile of the population, as regarding habits of solar exposure and sun protection measures. Results show that more than 75% of the measurements conducted in the summer (outside noon) can be classified as upper than high UVI according to World Health Organization (WHO) recommended categories: Low (UVI < 2), Medium (3 ? UVI < 6), High (6 ? UVI < 8), Very High (8 ? UVI

  9. The diffuse component of erythemal ultraviolet radiation.

    PubMed

    Silva, Abel A

    2015-11-01

    The diffuse (Dif) component of ultraviolet radiation (UVR) plays an important role in the daily exposure of humans to solar radiation. This study proposes a semi-empirical method to obtain the Dif component of the erythemal dose rate, or the erythemally weighted irradiance, (EDRDif) calculated from synchronized measurements of the Dif component of UVR (UVDif) and the global (G) irradiances of both UVR (UVG) and the erythemal dose rate (EDRG). Since the study was conducted in the tropics, results involve a wide range of solar zenith angles to which EDRDif is seasonally dependent. Clouds are the main atmospheric agent affecting Dif radiation. The ratio between Dif and G (Dif/G) showed a quadratic dependence on cloud cover with a coefficient of determination r(2) = 0.79. The maxima of EDRDif were mainly above the moderate range (>137.5 mW m(-2)) of the UV-Index and reached the extreme range (>262.5 mW m(-2)) for the spring-summer period. The fraction of the global daily erythemal dose (daily EDG) corresponding to Dif radiation (daily EDDif) ranged from 936 J m(-2) to 5053 J m(-2) and averaged 2673 J m(-2). Daily EDDif corresponded to at least 48% of daily EDG for a practically cloudless sky. Therefore, Dif radiation is a real threat. Lighter skin people (types I and II) can get sunburnt in a couple of minutes under such an incidence of radiation. Moreover, accumulative harm can affect all skin types. PMID:26313148

  10. Progress in understanding the diffuse UV cosmic background

    NASA Astrophysics Data System (ADS)

    Henry, Richard Conn

    I report on progress in my ongoing work with Professor Jayant Murthy concerning the origin and nature of the diffuse ultraviolet background radiation over the sky. We have obtained and are reducing a vast trove of Voyager ultraviolet spectrometer observations of the diffuse background shortward of Lalpha , including for the first time measurements made from the outermost regions of the solar system, where noise from solar-system scattered (and then grating-scattered) solar Lalpha is lowest. Also, we have obtained and are investigating the complete set of GALEX observations of the diffuse ultraviolet background longward of Lalpha . Preliminary investigation appears to confirm that longward of Lalpha there exists a component of the diffuse ultraviolet background that is not dust-scattered starlight.

  11. Physics of Electrodeless UV Lamps and Applications of UV Radiation

    NASA Astrophysics Data System (ADS)

    Cekic, Miodrag; Ruckman, Mark

    2004-12-01

    Electrodeless discharge microwave powered ultraviolet limps are a special class of high power incoherent UV sources, conceptualized forty years ago for industrial processing applications. Because of the nonimaging character of the applications, the need for measuring averaged properties of the lamps' exceeds the motivation to obtain detailed space-resolved discharge parameters. This writing discusses measurements of the average plasma temperature of a 5.8kW high pressure mercury bulb and a XeCl* excimer bulb driven by the microwaves of the same power. First method is based on the black body radiance fit to the self-absorbed 185nm and 254nm mercury lines. The second method is essentially Boltzmann plot method applied to the roto-vibrational levels of B1/2 - X1/2 XeCl* molecular transition with a maximum at 308nm. We also present a procedure for evaluation of effectiveness of different bulb spectra to the given UV curing chemistry system independent from the Beer-Lambert law. Conversely, the procedure can be used for the optimization of the chemistry to the chosen UV lamp radiance spectrum.

  12. The impact of solar UV radiation on the early biosphere

    NASA Astrophysics Data System (ADS)

    Horneck, G.

    2007-08-01

    Stratospheric ozone, photochemically produced from atmospheric oxygen, is a protective filter of the Earth's atmosphere by absorbing most of the biologically harmful UV radiation of our sun in the UV-C (190-280 nm) and short wavelength-region of the UV-B (280-315 nm). Numerous lines of isotopic and geologic evidence suggest that the Archean atmosphere was essentially anoxic. As a result the column abundance of ozone would have been insufficient to affect the surface UV radiation environment. Thus, as well as UV-B radiation, UV-C radiation would have penetrated to the Earth's surface with its associated biological consequences. The history of this ultraviolet stress for the early Earth has been determined from theoretical data and data obtained in Earth orbit on the inactivation of Bacillus subtilis spores under a simulated ozone layer of different thicknesses. Although the UV-C and UV-B regions contribute only 2 % of the entire solar extraterrestrial irradiance, photobiological experiments in space have demonstrated a high mutagenicity and lethality of this UV range to living organisms. The reason for these severe effects of extraterrestrial solar UV radiation - compared to conditions on present-day Earth - lies in the absorption characteristics of the DNA, which is the decisive target for inactivation and mutation induction at this UV range. Being a strong mutagen, UV-radiation is considered as a powerful promoter of biological evolution on the one hand, one the other hand, it may have deleterious consequences to individual cells and organisms, e.g. by causing inactivation, mutations or cancer induction. In response to potential harmful effects of environmental UV radiation, life on Earth has developed several strategies of survival, either avoiding exposure to UV radiation or restoring UV damage. Mechanisms of avoidance of exposure to UV radiation include (i) moving away from the UV radiation into shadowed areas, which requires the development of UV radiation

  13. Effective UV radiation dose in polyethylene exposed to weather

    NASA Astrophysics Data System (ADS)

    González-Mota, R.; Soto-Bernal, J. J.; Rosales-Candelas, I.; Calero Marín, S. P.; Vega-Durán, J. T.; Moreno-Virgen, R.

    2009-09-01

    In this work we quantified the effective UV radiation dose in orange and colorless polyethylene samples exposed to weather in the city of Aguascalientes, Ags. Mexico. The spectral distribution of solar radiation was calculated using SMART 2.9.5.; the samples absorption properties were measured using UV-Vis spectroscopy and the quantum yield was calculated using samples reflectance properties. The determining factor in the effective UV dose is the spectral distribution of solar radiation, although the chemical structure of materials is also important.

  14. Unstructured Polyhedral Mesh Thermal Radiation Diffusion

    SciTech Connect

    Palmer, T.S.; Zika, M.R.; Madsen, N.K.

    2000-07-27

    Unstructured mesh particle transport and diffusion methods are gaining wider acceptance as mesh generation, scientific visualization and linear solvers improve. This paper describes an algorithm that is currently being used in the KULL code at Lawrence Livermore National Laboratory to solve the radiative transfer equations. The algorithm employs a point-centered diffusion discretization on arbitrary polyhedral meshes in 3D. We present the results of a few test problems to illustrate the capabilities of the radiation diffusion module.

  15. [Study on the IR and UV dual-spectrum radiation].

    PubMed

    Chen, Z; Zhu, Q; Xu, S; Wan, S

    2000-06-01

    The article gives a method to produce dual spectrum radiation in IR and UV. Relying on theoretical analysis, the relative data are computed, some atomic materials are selected and added to a double-base propellants. When the UV pyrotechnics is ignited together with traditional IR pyrotechnics, the spectrum of IR and UV is emitted at the same time. The final measuring curves show that all results are satisfying. PMID:12958935

  16. UV Radiation Damage and Bacterial DNA Repair Systems

    ERIC Educational Resources Information Center

    Zion, Michal; Guy, Daniel; Yarom, Ruth; Slesak, Michaela

    2006-01-01

    This paper reports on a simple hands-on laboratory procedure for high school students in studying both radiation damage and DNA repair systems in bacteria. The sensitivity to ultra-violet (UV) radiation of both "Escherichia coli" and "Serratia marcescens" is tested by radiating them for varying time periods. Two growth temperatures are used in…

  17. Photosynthesis via Mineral Fluorescence in Harsh UV Radiation Environments

    NASA Astrophysics Data System (ADS)

    Barge, L. M.; Nealson, K.

    2005-12-01

    Before the development of a protective ozone layer about two billion years ago, the surface ultraviolet flux on Earth would have restricted ancient life to environments that offered some protection from direct solar radiation, such as the deep ocean or under or within rocks. In environments where the visible solar radiation would have been reduced to levels too low for photosynthesis, visible fluorescence resulting from UV irradiation of minerals may have provided a useable energy source. We are investigating the possibility that photosynthesis can occur without direct sunlight, if certain minerals are present that can absorb UV radiation and fluoresce in the visible. There are several common minerals(e.g. fluorite, calcite) that emit strong visible radiation under both short- and long-wave UV light, as well as some that only emit visible radiation under specific UV wavelengths. We will test a variety of minerals that fluoresce at wavelengths utilized by microbial chlorophylls and accessory pigments, and by simulating endolithic communities living under a few centimeters or millimeters of rock, we will measure the intensity of fluorescence and UV radiation received at various depths. We plan to simulate a variety of environments where the surface UV radiation may have a significant impact on the survival of life. These include the early Earth and present-day Mars(where the atmosphere would offer little to no protection against biologically damaging UV radiation), as well as extrasolar planets(a terrestrial planet in the habitable zone around an M-type star, for example, would be subject to an intense UV flux due to high flare activity). If mineral fluorescence proves to be a viable survival mechanism for photosynthetic organisms in harsh radiation environments, there are many implications for the study of ancient life on Earth as well as the search for life elsewhere.

  18. Influence of UV radiation on four freshwater invertebrates.

    PubMed

    Cywinska, A; Crump, D; Lean, D

    2000-11-01

    Laboratory tests confirmed a negative and variable response of the following four species to artificial UV radiation: Cypridopsis vidua, an ostracode; Chironomus riparius, a midge larvae; Hyalella azteca, an amphipod; and Daphnia magna, a daphnid. Severe damage occurred at UV-B irradiance ranging from 50 to 80% of incident summer values. Under constant exposure to UV and photosynthetically active radiation (PAR) the acute lethal response was recorded at 0.3, 0.8, 0.8 and 4.9 W m-2 UV-B for D. magna, H. azteca, C. riparius and C. vidua, respectively. Sublethal UV-B damage to invertebrates included impaired movement, partial paralysis, changes in pigmentation and altered water balance (bloating). A series of UV-B, UV-A and PAR treatments, applied separately and in combination, revealed a positive role for both UV-A and PAR in slowing down UV-B damage. Mean lethal concentration values of the species typically more tolerant to UV and PAR (Cypridopsis, Chironomus) decreased conspicuously when both UV-A and PAR were eliminated. For UV-B-sensitive species (Hyalella, Daphnia) these differences were notably smaller. We suggest that this gradation of sensitivity among the tested species demonstrates potential differences in repairing mechanisms which seem to work more efficiently for ostracodes and chironomids than for amphipods and daphnids. Manipulations with a cellulose acetate filter showed that lower range UV-B (280-290 nm), produced by FS-40 lamps, may cause excessive UV damage to invertebrates. PMID:11107851

  19. Prevent Eye Damage: Protect Yourself from UV Radiation

    MedlinePlus

    ... exposure to UV radiation from daily activities, including reflections off of snow, pavement, and other surfaces, can ... by a day at the beach without sunglasses; reflections off of snow, water, or concrete; or exposure ...

  20. Study of UV radiation dose received by the Spanish population.

    PubMed

    Gurrea, Gonzalo; Cañada, Javier

    2007-01-01

    Excess exposure to UV radiation can affect our health by causing sunburn, skin cancer, etc. It is therefore useful to determine the UV dosage received by people as a way of protecting them from the possible negative effects that this kind of radiation can cause. In this work, the personal outdoor percentage, which shows the time spent in outdoor activities, as well as personal UV doses, has been calculated by means of global UV radiation on a horizontal plane. A database of average daily UVB radiation on the horizontal plane given by the National Institute of Meteorology has been used. In this work we evaluate the standard erythema dose of the Spanish population throughout the year. PMID:18028210

  1. Sun, UV Radiation and Your Eyes

    MedlinePlus

    ... Protect their eyes with hats and sunglasses. UV Light: Good in Moderation for a Good Night's Sleep ... accumulated during the day. Some research suggests that light-sensitive cells in the eye are important to ...

  2. Kinetic parameters of uracil dosimeter in simulated extraterrestrial UV radiation

    NASA Astrophysics Data System (ADS)

    Kovács, G.; Gróf, P.; Bérces, A.; Patel, M. R.; Lammer, H.; Rontó, Gy.

    Studies of the solar UV environment on Earth 2.0 Gyr to 3.8 Gyr ago suggest that the terrestrial atmosphere was essentially anoxic, resulting in an ozone column abundance insufficient for protecting the planetary surface in the UV-B (280 nm - 315 nm) and the UV-C (200 nm - 280 nm) ranges. Since, short wavelength solar UV radiation in the UV-B and UV-C range penetrated through the atmosphere to the unprotected early Earth's surface, associated biological consequences may be expected. We discuss experimental data obtained as follows: Radiation sources applied were solar simulator and high power deuterium lamp, the wavelength were adjusted by interference filters (210, 230, 250 nm) and the irradiances were measured by OL754 spectroradiometer. The photo-reverse effect depends highly on the wavelength of the exposed radiation. Shorter wavelength UV radiation of about 200 nm is strongly effective in monomerization, while the longer wavelengths prefer the production of dimerization. In case of polychromatic light, like in space or on a planetary surface which is unprotected by an ozone layer the two processes run parallel. We could demonstrate experimentally, for the case of a uracil thin-layer that the photo-reaction process of the nucleotides can be both dimerization and the reverse process: monomerization. These results are important for the study of solar UV effects on organisms in the early terrestrial environment as well as for the search for life on Mars since we can show that biological harmful effects can also be reduced by shorter wavelength UV radiation, which is of importance in reducing DNA damages provoked by wavelengths longer than about 240 nm. Our earlier results showed that dimerization of the pyrimidin base uracil can be described by a first order kinetics, and this reaction gives the possibility to determine the dose of the UV source applied. This work is a theoretical and experimental approach to the relevant parameters of the first order kinetics.

  3. Measurements of the diffuse ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Fix, John D.; Craven, John D.; Frank, Louis A.

    1989-01-01

    The imaging instrumentation on the Dynamics Explorer 1 satellite has been used to measure the intensity of the diffuse ultraviolet radiation on two great circles about the sky. It is found that the isotropic component of the diffuse ultraviolet radiation (possibly of extragalactic origin) has an intensity of 530 + or - 80 units (a unit is 1 photon per sq cm s A sr) at a wavelength of 150 nm. The Galactic component of the diffuse ultraviolet radiation has a dependence on Galactic latitude which requires strongly forward scattering particles if it is produced by dust above the Galactic plane.

  4. Impact of UV-A radiation on erythemal UV and UV-index estimation over Korea

    NASA Astrophysics Data System (ADS)

    Park, Sang Seo; Lee, Yun Gon; Kim, Jung Hyun

    2015-12-01

    Because total UV (TUV) in the UV-A region is 100 times higher than in the UV-B region, UV-A is a considerable component when calculating erythemal UV (EUV) and UV-index. The ratio of EUV to TUV in the UV-A value [EUV(A)/TUV(A)] is investigated to convert the EUV(A) from TUV(A) for broadband observation. The representative value of EUV(A)/TUV(A), from the simulation study, is 6.9×10-4, changing from 6.1×10-4 to 7.0×10-4 as aerosol optical depth, total ozone and solar zenith angle change. By adopting the observational data of EUV(B) and TUV(A) from UV-biometer measurements at Yonsei University [(37.57°N, 126.95°E), 84 m above sea level], the EUV irradiance increases to 15% of EUV(B) due to the consideration of EUV(A) from the data of TUV(A) observation. Compared to the total EUV observed from the Brewer spectrophotometer at the same site, the EUV(B) from the UV-biometer observes only 95% of total EUV, and its underestimation is caused by neglecting the effect of UV-A. However, the sum of EUV(B) and EUV(A) [EUV(A+B)] from two UV-biometers is 10% larger than the EUV from the Brewer spectrophotometer because of the spectral overlap effect in the range 320-340 nm. The correction factor for the overlap effect adjusts 8% of total EUV.

  5. Ambient UV-B radiation causes deformities in amphibian embryos

    USGS Publications Warehouse

    Blaustein, A.R.; Kiesecker, J.M.; Chivers, D.P.; Anthony, R.G.

    1997-01-01

    There has been a great deal of recent attention on the suspected increase in amphibian deformities. However, most reports of amphibian deformities have been anecdotal, and no experiments in the field under natural conditions have been performed to investigate this phenomenon. Under laboratory conditions, a variety of agents can induce deformities in amphibians. We investigated one of these agents, UV-B radiation, in field experiments, as a cause for amphibian deformities. We monitored hatching success and development in long-toed salamanders under UV-B shields and in regimes that allowed UV-B radiation. Embryos under UV-B shields had a significantly higher hatching rate and fewer deformities, and developed more quickly than those exposed to UV-B. Deformities may contribute directly to embryo mortality, and they may affect an individual's subsequent survival after hatching.

  6. Diffuse Radiation from the Aquila Rift

    NASA Astrophysics Data System (ADS)

    Jyothy, S. N.; Murthy, Jayant; Karuppath, Narayanankutty; Sujatha, N. V.

    2015-12-01

    We present an analysis of the diffuse ultraviolet (UV) background in a low latitude region near the Aquila Rift based on observations made by the Galaxy Evolution Explorer (GALEX). The UV background is at a level of about 2000 ph cm-2 s-1 sr-1 Å-1 with no correlation with either the Galactic latitude or the 100 μm infrared (IR) emission. Rather, the UV emission falls off with distance from the bright B2 star HIP 88149, which is in the centre of the field. We have used a Monte Carlo model to derive an albedo of 0.6-0.7 in the UV with a phase function asymmetry factor (g) of 0.2-0.4. The value for the albedo is dependent on the dust distribution while g is determined by the extent of the halo.

  7. Protective effect of UV-A radiation during acclimation of the photosynthetic apparatus to UV-B treatment.

    PubMed

    Štroch, Michal; Materová, Zuzana; Vrábl, Daniel; Karlický, Václav; Šigut, Ladislav; Nezval, Jakub; Špunda, Vladimír

    2015-11-01

    We examined the acclimation response of the photosynthetic apparatus of barley (Hordeum vulgare L.) to a combination of UV-A and UV-B radiation (UVAB) and to UV-B radiation alone. Our aim was to evaluate whether UV-A radiation prevents UV-B-induced damage to the photosynthetic apparatus and whether UV-A pre-acclimation is required to mitigate the negative influence of UV-B radiation. Barley plants were grown from seeds under low photosynthetically active radiation (50 μmol m(-2) s(-1)) either in the absence or presence of UV-A radiation (UVA- and UVA+ plants, respectively). After 8 days of development, plants were exposed simultaneously to UV-A and UV-B radiation for the next 6 days. Additionally, UVA- plants were exposed to UV-B radiation alone. The UVA+ plants had a higher CO2 assimilation rate near the light-saturation region (A(N)) and a higher content of both total chlorophylls (Chls) and total carotenoids than the UVA- plants. Chls content, A(N), the potential quantum yield of photosystem II (PSII) photochemistry (F(V)/F(M)), the capacity of light-induced thermal energy dissipation and the efficiency of excitation energy transfer within PSII remained the same or even increased in both UVA+ and UVA- plants after UVAB treatment. On the contrary, exposure of UVA- plants to UV-B radiation itself led to a reduction in all these characteristics. We revealed that the presence of UV-A radiation during UVAB treatment not only mitigated but completely eliminated the negative effect of UV-B radiation on the functioning of the photosynthetic apparatus and that UV-A pre-acclimation was not crucial for development of this UV-A-induced resistance against UV-B irradiation. PMID:26233710

  8. Diffusion processes in general relativistic radiating spheres

    SciTech Connect

    Barreto, W.; Herrera, L.; Santos, N.O.; Universidad Central de Venezuela, Caracas; Observatorio Nacional do Brasil, Rio de Janeiro )

    1989-09-01

    The influence of diffusion processes on the dynamics of general relativistic radiating spheres is systematically studied by means of two examples. Differences between the streaming-out limit and the diffusion limit are exhibited, for both models, through the evolution curves of dynamical variables. In particular it is shown the Bondi mass decreases, for both models, in the diffusion limit as compared with its value at the streaming-out regime. 15 refs.

  9. IMPACT OF UV-B RADIATION UPON ESTUARINE MICROCOSMS

    EPA Science Inventory

    Twelve flow-through estuarine microcosms were exposed daily to four different levels of UV-B radiation. In addition to a natural level of visible solar radiation. The parameters studied over a four week period were phytoplankton community composition, plankton biomass (ash-free d...

  10. Shadow-band correction for diffuse ultraviolet radiation measurements

    NASA Astrophysics Data System (ADS)

    SáNchez, G.; Serrano, A.; Cancillo, M. L.

    2013-05-01

    the correction of shadow-band solar total diffuse measurements has been extensively studied, the case of diffuse ultraviolet measurements has not been properly addressed. This study analyzes the correction factor to be applied to experimental measurements performed adapting a shadow-band to a UV radiometer at a radiometric station in Badajoz (Spain). Three different models, based on approaches widely used for correcting total diffuse measurements, have been revised and adapted for the ultraviolet spectral range. Results reveal that some aspects of the correction proposed for total diffuse radiation are not suitable for ultraviolet diffuse radiation. The mathematical expressions are consequently modified to match the behavior in the ultraviolet range. Thus, three correction models particularized for ultraviolet diffuse measurements are proposed and validated against experimental data. The two models adapted from the original expressions proposed by Battles et al., and Steven show the best performance, with rRMSE of 2.74% and 2.20% and rMBE of 1.53% and 0.46%, respectively.

  11. Radiative models for the evaluation of the UV radiation at the ground.

    PubMed

    Koepke, P

    2009-12-01

    The variety of radiative models for solar UV radiation is discussed. For the evaluation of measured UV radiation at the ground the basic problem is the availability of actual values of the atmospheric parameters that influence the UV radiation. The largest uncertainties are due to clouds and aerosol, which are highly variable. In the case of tilted receivers, like the human skin for most orientations, and for conditions like a street canyon or tree shadow, besides the classical radiative transfer in the atmosphere additional modelling is necessary. PMID:19828720

  12. UV radiation induces CXCL5 expression in human skin.

    PubMed

    Reichert, Olga; Kolbe, Ludger; Terstegen, Lara; Staeb, Franz; Wenck, Horst; Schmelz, Martin; Genth, Harald; Kaever, Volkhard; Roggenkamp, Dennis; Neufang, Gitta

    2015-04-01

    CXCL5 has recently been identified as a mediator of UVB-induced pain in rodents. To compare and to extend previous knowledge of cutaneous CXCL5 regulation, we performed a comprehensive study on the effects of UV radiation on CXCL5 regulation in human skin. Our results show a dose-dependent increase in CXCL5 protein in human skin after UV radiation. CXCL5 can be released by different cell types in the skin. We presumed that, in addition to immune cells, non-immune skin cells also contribute to UV-induced increase in CXCL5 protein. Analysis of monocultured dermal fibroblasts and keratinocytes revealed that only fibroblasts but not keratinocytes displayed up regulated CXCL5 levels after UV stimulation. Whereas UV treatment of human skin equivalents, induced epidermal CXCL5 mRNA and protein expression. Up regulation of epidermal CXCL5 was independent of keratinocyte differentiation and keratinocyte-keratinocyte interactions in epidermal layers. Our findings provide first evidence on the release of CXCL5 in UV-radiated human skin and the essential role of fibroblast-keratinocyte interaction in the regulation of epidermal CXCL5. PMID:25690483

  13. Effective UV radiation from model calculations and measurements

    NASA Technical Reports Server (NTRS)

    Feister, Uwe; Grewe, Rolf

    1994-01-01

    Model calculations have been made to simulate the effect of atmospheric ozone and geographical as well as meteorological parameters on solar UV radiation reaching the ground. Total ozone values as measured by Dobson spectrophotometer and Brewer spectrometer as well as turbidity were used as input to the model calculation. The performance of the model was tested by spectroradiometric measurements of solar global UV radiation at Potsdam. There are small differences that can be explained by the uncertainty of the measurements, by the uncertainty of input data to the model and by the uncertainty of the radiative transfer algorithms of the model itself. Some effects of solar radiation to the biosphere and to air chemistry are discussed. Model calculations and spectroradiometric measurements can be used to study variations of the effective radiation in space in space time. The comparability of action spectra and their uncertainties are also addressed.

  14. Double-layer anisotropic light diffusion films fabricated using a two-step UV curing technique

    NASA Astrophysics Data System (ADS)

    Kusama, Kentaro; Ishinabe, Takahiro; Katagiri, Baku; Orui, Tomoo; Shoshi, Satoru; Fujikake, Hideo

    2016-04-01

    We developed a novel light diffusion film with a double diffusion layer structure for high reflectivity and a wide diffusion angle range. We demonstrated that the internal layer structure of the light diffusion film is controlled by the diffusion angle of the ultraviolet (UV) light used for photopolymerization. We successfully fabricated two different diffusion layers in a single polymer film using a two-step UV curing process and achieved a wide diffusion angle range and high reflectivity normal to the film surface. Our light diffusion film can control the distribution of diffused light, and should contribute to the development of future low-power reflective displays with high reflectivity similar to the white paper.

  15. Ozone depletion and climate change: impacts on UV radiation.

    PubMed

    Bais, A F; McKenzie, R L; Bernhard, G; Aucamp, P J; Ilyas, M; Madronich, S; Tourpali, K

    2015-01-01

    We assess the importance of factors that determine the intensity of UV radiation at the Earth's surface. Among these, atmospheric ozone, which absorbs UV radiation, is of considerable importance, but other constituents of the atmosphere, as well as certain consequences of climate change, can also be major influences. Further, we assess the variations of UV radiation observed in the past and present, and provide projections for the future. Of particular interest are methods to measure or estimate UV radiation at the Earth's surface. These are needed for scientific understanding and, when they are sufficiently sensitive, they can serve as monitors of the effectiveness of the Montreal Protocol and its amendments. Also assessed are several aspects of UV radiation related to biological effects and health. The implications for ozone and UV radiation from two types of geoengineering methods that have been proposed to combat climate change are also discussed. In addition to ozone effects, the UV changes in the last two decades, derived from measurements, have been influenced by changes in aerosols, clouds, surface reflectivity, and, possibly, by solar activity. The positive trends of UV radiation observed after the mid-1990s over northern mid-latitudes are mainly due to decreases in clouds and aerosols. Despite some indications from measurements at a few stations, no statistically significant decreases in UV-B radiation attributable to the beginning of the ozone recovery have yet been detected. Projections for erythemal irradiance (UVery) suggest the following changes by the end of the 21(st) century (2090-2100) relative to the present time (2010-2020): (1) Ozone recovery (due to decreasing ozone-depleting substances and increasing greenhouse gases) would cause decreases in UVery, which will be highest (up to 40%) over Antarctica. Decreases would be small (less than 10%) outside the southern Polar Regions. A possible decline of solar activity during the 21(st) century

  16. Uranium plasma radiates in the UV spectrum

    NASA Technical Reports Server (NTRS)

    Williams, M. D.

    1973-01-01

    Description of an experiment designed to produce and spectroscopically analyze a simulated gas core reactor plasma in the spectral range from 300 to 1300 A. The plasma was produced by focusing the radiation of a Q-spoiled ruby laser onto the flat surface of a pure U-238 specimen.

  17. Oxidation of polynuclear aromatic hydrocarbons in water. 2: UV radiation and ozonation in the presence of UV radiation

    SciTech Connect

    Beltran, F.J.; Garcia-Araya, J.F.; Rivas, J.; Ovejero, G.

    1995-05-01

    Direct photolysis with UV radiation (254 nm) and oxidation with ozone combined with UV radiation of three polynuclear aromatic hydrocarbons, fluorene, phenanthrene, and acenaphthene, has been studied. Quantum yields of the direct photolysis of the PAHs determined were 7.5 {times} 10{sup {minus}3}, 6.9 {times} 10{sup {minus}3}, and 52 {times} 10{sup {minus}3} mol(photon){sup {minus}1} for fluorene, phenanthrene, and acenaphthene, respectively. Contributions of direct ozonation, direct photolysis, and radical oxidation have also been estimated for the oxidation with ozone combined with UV radiation. Fluorene is oxidized by direct photolysis and radical reactions, phenanthrene through direct mechanisms, ozonation, and photolysis, and acenaphthene mainly by direct ozonation.

  18. SMX degradation by ozonation and UV radiation: a kinetic study.

    PubMed

    Liu, Xiaowei; Garoma, Temesgen; Chen, Zhonglin; Wang, Lili; Wu, Youxian

    2012-06-01

    The rate constants of sulfamethoxazole (SMX) degradation by ozonation and UV(254) radiation were investigated under various parameters including influent ozone gas concentration, initial SMX concentration, UV light intensity, ionic strength, water quality in terms of varying anions (bicarbonate, sulfate and nitrate), humic acid (HA) and pH. The results indicated that the removal of SMX by ozonation and UV(254) radiation fitted well to a pseudo first-order kinetic model and the rate constants were in the range of (0.9-9.8)×10(-3) and (1.7-18.9)×10(-3) s(-1), respectively. The second-order rate constants of SMX with ozone (ko(3)), under varying operational parameters, were also determined and varied in the range of (0.60-3.38)±0.13×10(5)M(-1) s(-1). In addition, SMX degradation through UV pretreatment followed by ozonation in the presence of HA was proved to be an effective method which can remove SMX with a low ozone dose. The results suggested that ozonation of SMX was more affected by concentration of influent ozone gas, alkalinity, and HA, while incident UV light intensity, pH, and HA were the dominant factors influencing UV degradation of SMX. PMID:22386457

  19. Spectral Observations of the Diffuse FUV Background with DUVE (the Diffuse UV Experiment)

    NASA Astrophysics Data System (ADS)

    Korpela, E. J.; Bowyer, S.

    1996-05-01

    We present results from a search for FUV emission from the diffuse ISM conducted with an orbital FUV spectrometer, DUVE, which was launched in July, 1992. The DUVE spectrometer, which covers the band from 970 Angstroms to 1170 Angstroms with 3.2 angstrom resolution, observed a region of low neutral hydrogen column desity near the south galactic pole for a total effective integration time of 1583 seconds. The only emission line detected was a geocoronal hydrogen line 1026 Angstroms. We were, however, able to place upper limits to several important interstellar emission features in this band. We compare these upper limits with predictions of FUV emission based upon several models of the structure of the hot ISM and place limits on the emission measure vs temperature distribution this gas. We also compare these emission measure limits with those obtained from measurements in other optical, UV and X-ray bands.

  20. ESTIMATION OF UV RADIATION DOSE IN NORTHERN MINNESOTA WETLANDS

    EPA Science Inventory

    The ultraviolet (UV) B wavelength range (280 nm to 320 nm) of solar radiation can be a significant biological stressor, and has been hypothesized to be partially responsible for amphibian declines and malformation. This hypothesis has been difficult to evaluate, in part, because ...

  1. Tuning the SMS spectrum based on UV radiation

    NASA Astrophysics Data System (ADS)

    Zhong, Di; Tian, Ye; Zhang, Jianzhong; Sun, Weimin; Yuan, Libo

    2014-05-01

    We propose a fine spectrum-tuning scheme of the single-multi-single mode fiber (SMS) structure, realised by using UV radiation to modify the propagation constants of different modes in Multi-mode fiber of SMS. The primary experiments also demonstrated. It expect to have applications in the design of SMS based optical filters and sensors.

  2. Improving radiation data quality of USDA UV-B monitoring and research program and evaluating UV decomposition in DayCent and its ecological impacts

    NASA Astrophysics Data System (ADS)

    Chen, Maosi

    from an improved cloud screening algorithm that utilizes an iterative rejection of cloudy points based on a decreasing tolerance of unstable optical depth behavior when calibration information is unknown. A MODTRAN radiative transfer model simulation showed the new cloud screening algorithm was capable of screening cloudy points while retaining clear-sky points. The comparison results showed that the cloud-free points determined by the new cloud screening algorithm generated significantly (56%) more and unbiased Langley offset voltages (VLOs) for both partly cloudy days and sunny days at two testing sites, Hawaii and Florida. The V¬LOs are proportional to the radiometric sensitivity. The stability of the calibration is also improved by the development of a two-stage reference channel calibration method for collocated UV-MFRSR and MFRSR instruments. Special channels where aerosol is the only contributor to total optical depth (TOD) variation (e.g. 368-nm channel) were selected and the radiative transfer model (MODTRAN) used to calculate direct normal and diffuse horizontal ratios which were used to evaluate the stability of TOD in cloud-free points. The spectral dependence of atmospheric constituents' optical properties and previously calibrated channels were used to find stable TOD points and perform Langley calibration at spectrally adjacent channels. The test of this method on the UV-B program site at Homestead, Florida (FL02) showed that the new method generated more clustered and abundant VLOs at all (UV-) MFRSR channels and potentially improved the accuracy by 2-4% at most channels and over 10% at 300-nm and 305-nm channels. In the second major part of this work, I calibrated the DayCent-UV model with ecosystem variables (e.g. soil water, live biomass), allowed maximum photodecay rate to vary with litter's initial lignin fraction in the model, and validated the optimized model with LIDET observation of remaining carbon and nitrogen at three semi-arid sites. I

  3. Measurement of solar UV radiation in Antarctica with collagen sheets.

    PubMed

    Takahashi, Tetsuya; Kondo, Tetsuo; Tanaka, Keisuke; Hattori, Shunji; Irie, Shinkichi; Kudoh, Sakae; Imura, Satoshi; Kanda, Hiroshi

    2012-07-01

    Collagen sheets were used in a unique evaluation method to examine skin damage caused by ultraviolet (UV) light of short wavelength during a season of the Antarctic ozone hole. The collagen sheets were exposed outdoors for 25 and 50 d, in the spring when the ozone hole was formed and in the ozone-hole-free autumn. Extracts from the exposed collagen sheets were analyzed for total protein and terminal amino acid concentrations as an index of collagen fragmentation. The results show that the amount of extractable collagen and terminal amino acid concentration in the spring exposure were approximately double and five times higher, respectively, when compared with those in the autumn exposure. During the ozone hole occurrence, the terminal amino acid concentration of the extracted collagen was about five times higher when exposure lasted 50 d from mid-September to the end of October compared to when exposure lasted 25 d from mid-September to early October. This result could be attributed to a limited amount of short-wavelength UV radiation reaching the ground surface as a result of the low height of the sun in September, when the ozone hole occurred. In fact, UV radiation measurements taken at Syowa Station indicate that short-wavelength UV radiation in the range 290-295 nm was not detected until approximately 1-2 months after the beginning of the ozone hole occurrence. PMID:22419356

  4. Assessment of diffuse radiation models in Azores

    NASA Astrophysics Data System (ADS)

    Magarreiro, Clarisse; Brito, Miguel; Soares, Pedro; Azevedo, Eduardo

    2014-05-01

    Measured irradiance databases usually consist of global solar radiation data with limited spatial coverage. Hence, solar radiation models have been developed to estimate the diffuse fraction from the measured global irradiation. This information is critical for the assessment of the potential of solar energy technologies; for example, the decision to use photovoltaic systems with tracking system. The different solar radiation models for this purpose differ on the parameters used as input. The simplest, and most common, are models which use global radiation information only. More sophisticated models require meteorological parameters such as information from clouds, atmospheric turbidity, temperature or precipitable water content. Most of these models comprise correlations with the clearness index, kt (portion of horizontal extra-terrestrial radiation reaching the Earth's surface) to obtain the diffuse fraction kd (portion of diffuse component from global radiation). The applicability of these different models is related to the local atmospheric conditions and its climatic characteristics. The models are not of general validity and can only be applicable to locations where the albedo of the surrounding terrain and the atmospheric contamination by dust are not significantly different from those where the corresponding methods were developed. Thus, models of diffuse fraction exhibit a relevant degree of location dependence: e.g. models developed considering data acquired in Europe are mainly linked to Northern, Central or, more recently, Mediterranean areas. The Azores Archipelago, with its particular climate and cloud cover characteristics, different from mainland Europe, has not yet been considered for the development of testing of such models. The Azorean climate reveals large amounts of cloud cover in its annual cycle, with spatial and temporal variabilities more complex than the common Summer/Winter pattern. This study explores the applicability of different

  5. Diffuse ionizing radiation within HH jets

    SciTech Connect

    Esquivel, A.; Raga, A. C. E-mail: raga@nucleares.unam.mx

    2013-12-20

    We present numerical hydrodynamical simulations of a time-dependent ejection velocity precessing jet. The parameters used in our models correspond to a high excitation Herbig-Haro object, such as HH 80/81. We have included the transfer of ionizing radiation produced within the shocked regions of the jet. The radiative transfer is computed with a ray-tracing scheme from all the cells with an emissivity above a certain threshold. We show the development of a radiative precursor, and compare the morphology with a model without the diffuse radiation. Our simulations show that the morphology of the Hα emission is affected considerably if the diffuse ionizing radiation is accounted for. The predicted Hα position-velocity diagram (i.e., spatially resolved emission line profiles) from a model with the transfer of ionizing radiation has a relatively strong component at zero velocity, corresponding to the radiative precursor. Qualitatively similar 'zero velocity components' are observed in HH 80/81 and in the jet from Sanduleak's star in the Large Magellanic Cloud.

  6. Effects of Enhanced UV-B Radiation on Biochemical Traits in Postharvest Flowers of Medicinal Chrysanthemum.

    PubMed

    Si, Chao; Yao, Xiao-Qin; He, Xue-Li; Chu, Jian-Zhou; Ma, Chun-Hui; Shi, Xiao-Fei

    2015-01-01

    This article reported UV-B radiation effects on biochemical traits in postharvest flowers of chrysanthemum. The experiment included six levels of UV-B radiation (UV0, 0 μW cm(-2); UV50, 50 μW cm(-2); UV200, 200 μW cm(-2); UV400, 400 μW cm(-2); UV600, 600 μW cm(-2) and UV800, 800 μW cm(-2). Enhanced UV-B radiation significantly increased hydrogen peroxide content (except for UV50), but did not evidently affect malondialdehyde content in flowers. Chlorophyll b and total chlorophyll content were significantly increased by UV600 and UV800. UV400 and UV600 significantly increased anthocyanins, carotenoids and UV-B absorbing compounds content, and the activities of phenylalanine ammonia lyase (PAL) and cinnamic acid-4-hydroxylase (C4H) over the control. 4-coumarate CoA ligase (4CL) activity was significantly decreased by enhanced UV-B radiation (except for UV50). The relationships between UV-B radiation intensities and the activities of secondary metabolism enzymes were best described by a second-order polynomial. The R(2) values for UV-B radiation intensities and the activities of PAL, C4H and 4CL were 0.8361, 0.5437 and 0.8025, respectively. The results indicated that enhanced UV-B radiation could promote secondary metabolism processes in postharvest flowers, which might be beneficial for the accumulation of medically active ingredients in medicinal plants. The optimal UV-B radiation intensities in the study were between UV400-UV600. PMID:25778827

  7. UV Radiation in an Urban Canyon in Southeast Queensland

    NASA Astrophysics Data System (ADS)

    McKinley, A. R.; Moore, M. R.; Kimlin, M. G.

    2006-12-01

    Ultraviolet radiation (UV) has the possibility to both harm and to benefit human beings when unprotected exposure occurs. After receiving small amounts of UV our bodies begin to synthesise vitamin D, which is essential for maintaining healthy bones, however excessive UV exposure can result in a variety of damaging outcomes ranging from sunburn to skin cancer and cataracts. For this reason it is very important to understand the different environments in which people encounter UV so as to better prepare the public to make smart and healthy sun exposure decisions. Each day more and more people are moving into large cities around the world and spending their time inside the urban canyon, however UV measurements are generally taken at scientific stations in open areas or on top of tall buildings, meaning that at times the environmental characteristics measured may not accurately represent those found at street-level in these highly urbanized areas. Urban canyons are home to both very tall buildings and tropospheric air pollution, each of which reduces the amount of UV reaching street-level. This study measured the varying difference between UV measurements taken at street-level and at a standard UV monitoring site on top of a building outside of the urban canyon. Investigation was conducted in the central business district (CBD) of Brisbane, Australia, which models the CBDs of large cities around the world in that it boasts a great number of tall buildings, including many skyscrapers. Data was collected under clear sky conditions at five different street-level sites in the CBD (on either side of two streets running perpendicular to one another (four sites) and in a public square) and then compared to that obtained on the same day at the Queensland University of Technology's Australian Sun and Health Research Laboratory (ASHRL), which is located 2.5 kilometres outside Brisbane's CBD. Minimum erythemal dose (MED) data was collected at each location and it was found that

  8. Penetration of UV Radiation in the Earth's Oceans

    NASA Technical Reports Server (NTRS)

    Mitchell, B. Greg; Lubin, Dan

    2005-01-01

    This project was a collaboration between SIO/UCSD and NASA/GSFC to develop a global estimation of the penetration of UV light into open ocean waters, and into coastal waters. We determined the ocean UV reflectance spectra seen by satellites above the atmosphere by combining existing sophisticated radiative transfer models with in situ UV Visible data sets to improve coupled radiance estimates both underwater and within the atmosphere. Results included improved estimates of surface spectral irradiance, 0.3-1.0 micron, and estimates of photosynthetic inhibition, DNA mutation, and CO production. Data sets developed under this proposal have been made publicly available via submission to the SeaWiFS Bio-Optical Archive and Storage System. Numerous peer-reviewed publications and conference proceedings and abstracts resulted from the work supported by this research award.

  9. Methodes and apparature for precise measurements of solar UV radiation

    NASA Astrophysics Data System (ADS)

    Anevsky, S.; Ivanov, V.; Minaeva, O.; Morozov, O.; Sapritsky, V.

    2003-04-01

    The precise measurements of solar UV radiation are based on the use of the national primary standards of the flux, irradiance and spectral radiance. Standard sources and detectors were developed for the establishing of spectral and integral irradiance units for regions UV-A, -A1,-A2, -B, -C, herythemical, dangerous and other effective and UV irradiance. The primary standard detector is based on the high-responsivety pneumatic thermoelement with electrical substitution. The primary standard sources are based on the high-temperature black-body model and laboratory synchrotron radiation sources with strong magnetic field [1, 2]. For the integral effective irradiance standards are used the tabulated spectral coefficients of UV action. As the secondary standard for the spectral range of air UV was created the integral multichannel filter radiometer. The investigations of the main UV sources spectral irradiance allowed to optimize the number of parallel channels. Multichannel radiometer permits to estimate the spectral irradiance of any UV sources and to measure integral and effective characteristics with high precision. Every channel consists of high-quality interference filter, special photodiode with spectral responsivety in the range from 200 to 650 nm and operational amplifier. The high responsivety level of each channel permits to use the integral sphere for creation of the cosine angular dependence. The creation of primary and secondary standards lets to compare the quality of any types of ordinary one-channel radiometers developed for applications in photobiology, ozon monitoring and solar radiation material protection. The investigations of the integral responsivety of one-channel radiometers by use of the set of control UV sources with small dimensions of the emitting area permit to estimate the quality of their spectral corrections, to calculate the coefficients of the spectral corrections and to restrict their applications. The same approach was developed for

  10. Ecological responses to UV radiation: interactions between the biological effects of UV on plants and on associated organisms.

    PubMed

    Paul, Nigel D; Moore, Jason P; McPherson, Martin; Lambourne, Cathryn; Croft, Patricia; Heaton, Joanna C; Wargent, Jason J

    2012-08-01

    Solar ultraviolet (UV)-B radiation (280-315 nm) has a wide range of effects on terrestrial ecosystems, yet our understanding of how UV-B influences the complex interactions of plants with pest, pathogen and related microorganisms remains limited. Here, we report the results of a series of experiments in Lactuca sativa which aimed to characterize not only key plant responses to UV radiation in a field environment but also consequential effects for plant interactions with a sap-feeding insect, two model plant pathogens and phylloplane microorganism populations. Three spectrally modifying filters with contrasting UV transmissions were used to filter ambient sunlight, and when compared with our UV-inclusive filter, L. sativa plants grown in a zero UV-B environment showed significantly increased shoot fresh weight, reduced foliar pigment concentrations and suppressed population growth of green peach aphid (Myzus persicae). Plants grown under a filter which allowed partial transmission of UV-A radiation and negligible UV-B transmission showed increased density of leaf surface phylloplane microbes compared with the UV-inclusive treatment. Effects of UV treatment on the severity of two plant pathogens, Bremia lactucae and Botrytis cinerea, were complex as both the UV-inclusive and zero UV-B filters reduced the severity of pathogen persistence. These results are discussed with reference to known spectral responses of plants, insects and microorganisms, and contrasted with established fundamental responses of plants and other organisms to solar UV radiation, with particular emphasis on the need for future integration between different experimental approaches when investigating the effects of solar UV radiation. PMID:22150399

  11. Effects of solar UV-B radiation on aquatic ecosystems

    NASA Astrophysics Data System (ADS)

    Häder, D.-P.

    Solar UV degrades dissolved organic carbon photolytically so that they can readily be taken up by bacterioplankton. On the other hand solar UV radiation inhibits bacterioplankton activity. Bacterioplankton productivity is far greater than previously thought and is comparable to phytoplankton primary productivity. According to the "microbial loop hypothesis," bacterioplankton is seen in the center of a food web, having a similar function to phytoplankton and protists. The penetration of UV and PAR into the water column can be measured. Marine waters show large temporal and regional differences in their concentrations of dissolved and particulate absorbing substances. A network of dosimeters (ELDONET) has been installed in Europe ranging from Abisko in Northern Sweden to Gran Canaria. Cyanobacteria are capable of fixing atmospheric nitrogen which is then made available to higher plants. The agricultural potential of cyanobacteria has been recognized as a biological fertilizer for wet soils such as in rice paddies. UV-B is known to impair processes such as growth, survival, pigmentation, motility, as well as the enzymes of nitrogen metabolism and CO 2 fixation. The marine phytoplankton represents the single most important ecosystem on our planet and produces about the same biomass as all terrestrial ecosystems taken together. It is the base of the aquatic food chain and any changes in the size and composition of phytoplankton communities will directly affect food production for humans from marine sources. Another important role of marine phytoplankton is to serve as a sink for atmospheric carbon dioxide. Recent investigations have shown a large sensitivity of most phytoplankton organisms toward solar short-wavelength ultraviolet radiation (UV-B); even at ambient levels of UV-B radiation many organisms seem to be under UV stress. Because of their requirement for solar energy, the phytoplankton dwell in the top layers of the water column. In this near-surface position

  12. Effects of solar UV-B radiation on aquatic ecosystems.

    PubMed

    Hader, D P

    2000-01-01

    Solar UV degrades dissolved organic carbon photolytically so that they can readily be taken up by bacterioplankton. On the other hand solar UV radiation inhibits bacterioplankton activity. Bacterioplankton productivity is far greater than previously thought and is comparable to phytoplankton primary productivity. According to the "microbial loop hypothesis," bacterioplankton is seen in the center of a food web, having a similar function to phytoplankton and protists. The penetration of UV and PAR into the water column can be measured. Marine waters show large temporal and regional differences in their concentrations of dissolved and particulate absorbing substances. A network of dosimeters (ELDONET) has been installed in Europe ranging from Abisko in Northern Sweden to Gran Canaria. Cyanobacteria are capable of fixing atmospheric nitrogen which is then made available to higher plants. The agricultural potential of cyanobacteria has been recognized as a biological fertilizer for wet soils such as in rice paddies. UV-B is known to impair processes such as growth, survival, pigmentation, motility, as well as the enzymes of nitrogen metabolism and CO2 fixation. The marine phytoplankton represents the single most important ecosystem on our planet and produces about the same biomass as all terrestrial ecosystems taken together. It is the base of the aquatic food chain and any changes in the size and composition of phytoplankton communities will directly affect food production for humans from marine sources. Another important role of marine phytoplankton is to serve as a sink for atmospheric carbon dioxide. Recent investigations have shown a large sensitivity of most phytoplankton organisms toward solar short-wavelength ultraviolet radiation (UV-B); even at ambient levels of UV-B radiation many organisms seem to be under UV stress. Because of their requirement for solar energy, the phytoplankton dwell in the top layers of the water column. In this near-surface position

  13. uv radiation curable paints. Topical report on material identification

    SciTech Connect

    Not Available

    1981-01-13

    The program for the development of ultraviolet radiation curing of paints for application on preformed structures is discussed. The starting point of this program was the matching of resins, photoinitiators, and pigments which will result in coatings that can be cured by ultraviolet radiation. The initial work was the identification of reactive diluents and base resins that are sensitive to the uv curing process. The reactive monomeric diluents tested included multifunctional acrylates, monofunctional acrylates, and non-acrylic unsaturated esters. The end point will be the application of these coatings to prefabricated metal structures to demonstrate the viability of this technique in producing commercially acceptable painted products. These uv curable paints should produce films that are hard, adherent, and opaque at a nominal thickness of one mil (0.001 inch).

  14. Simulation of the UV-radiation at the Martian surface

    NASA Astrophysics Data System (ADS)

    Kolb, C.; Stimpfl, P.; Krenn, H.; Lammer, H.; Kargl, G.; Abart, R.; Patel, M. R.

    The UV-radiation at the Martian surface is for several reasons of importance. UV radiation can cause specific damages in the DNA-containing living systems and is involved in the formation of catalytically produced oxidants such as superoxide ions and peroxides. These are capable to oxidize and subsequently destroy organic matter. Lab simulations are necessary to investigate and understand the effects of organic matter removal at the Martian surface. We designed a radiation apparatus which simulates the solar spectrum at the Martian surface between 200 and 700 nm. The system consists of an UV-enhanced xenon arc lamp and special exchangeable filter-sets and mirrors for simulating the effects of the Martian atmospheric column and dust loading. A special collimating system bundles the final parallel beam so that the intensity at the target spot is independent from the distance between the ray source and the sample. The system was calibrated by means of an optical photo-spectrometer to align the ray output with the theoretical target spectrum and to ensure spectral homogeneity. We present preliminary data on calibration and performance of our system, which is integrated in the Austrian Mars simulation facility.

  15. Photoablation of polyimide with IR and UV laser radiation

    NASA Astrophysics Data System (ADS)

    Braun, R.; Nowak, R.; Hess, P.; Oetzmann, H.; Schmidt, C.

    1989-12-01

    IR and UV ablation experiments were performed for freestanding polyimide foils (75 μm) and spincoated films of polyimide (6-7 μm). Compared to results reported in the literature a considerably improved etch quality was obtained with a pulsed TEA CO2 laser. Distinct interference effects were found for KrF laser radiation and CO2 laser radiation. The fluence dependence of the etch rates was studied for excimer laser light at 248 nm and IR laser light at 1082.3, 1057.3 and 970.5 cm-1. The optical absorption coefficient was determined by reflectivity and transmittance measurements.

  16. Diffusion models for Jupiter's radiation belt

    NASA Technical Reports Server (NTRS)

    Jacques, S. A.; Davis, L., Jr.

    1972-01-01

    Solutions are given for the diffusion of trapped particles in a planetary magnetic field in which the first and second adiabatic invariants are preserved but the third is not, using as boundary conditions a fixed density at the outer boundary (the magnetopause) and a zero density at an inner boundary (the planetary surface). Losses to an orbiting natural satellite are included and an approximate evaluation is made of the effects of the synchrotron radiation on the energy of relativistic electrons. Choosing parameters appropriate to Jupiter, the electrons required to produce the observed synchrotron radiation are explained. If a speculative mechanism in which the diffusion is driven by ionospheric wind is the true explanation of the electrons producing the synchrotron emission it can be concluded that Jupiter's inner magnetosphere is occupied by an energetic proton flux that would be a serious hazard to spacecraft.

  17. Ozone depletion and climate change: impacts on UV radiation.

    PubMed

    McKenzie, R L; Aucamp, P J; Bais, A F; Björn, L O; Ilyas, M; Madronich, S

    2011-02-01

    The Montreal Protocol is working, but it will take several decades for ozone to return to 1980 levels. The atmospheric concentrations of ozone depleting substances are decreasing, and ozone column amounts are no longer decreasing. Mid-latitude ozone is expected to return to 1980 levels before mid-century, slightly earlier than predicted previously. However, the recovery rate will be slower at high latitudes. Springtime ozone depletion is expected to continue to occur at polar latitudes, especially in Antarctica, in the next few decades. Because of the success of the Protocol, increases in UV-B radiation have been small outside regions affected by the Antarctic ozone hole, and have been difficult to detect. There is a large variability in UV-B radiation due to factors other than ozone, such as clouds and aerosols. There are few long-term measurements available to confirm the increases that would have occurred as a result of ozone depletion. At mid-latitudes UV-B irradiances are currently only slightly greater than in 1980 (increases less than ~5%), but increases have been substantial at high and polar latitudes where ozone depletion has been larger. Without the Montreal Protocol, peak values of sunburning UV radiation could have been tripled by 2065 at mid-northern latitudes. This would have had serious consequences for the environment and for human health. There are strong interactions between ozone depletion and changes in climate induced by increasing greenhouse gases (GHGs). Ozone depletion affects climate, and climate change affects ozone. The successful implementation of the Montreal Protocol has had a marked effect on climate change. The calculated reduction in radiative forcing due to the phase-out of chlorofluorocarbons (CFCs) far exceeds that from the measures taken under the Kyoto protocol for the reduction of GHGs. Thus the phase-out of CFCs is currently tending to counteract the increases in surface temperature due to increased GHGs. The amount of

  18. Solar UV Radiation and the Origin of Life on Earth

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Hubeny, Ivan; Lanz, Thierry; Gaidos, Eric; Kasting, James; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    We have started a comprehensive, interdisciplinary study of the influence of solar ultraviolet radiation on the atmosphere of of the early Earth. We plan to model the chemistry of the Earth atmosphere during its evolution, using observed UV flux distributions of early solar analogs as boundary conditions in photochemical models of the Earth's atmosphere. The study has four distinct but interlinked parts: (1) Establishing the radiation of the early Sun; (2) Determining the photochemistry of the early Earth's atmosphere; (3) Estimating the rates of H2 loss from the atmosphere; and (4) Ascertaining how sensitive is the photochemistry to the metallicity of the Sun. We are currently using STIS and EUVE to obtain high-quality far-UV and extreme-UV observations of three early-solar analogs. We will perform a detailed non-LTE study of each stars, and construct theoretical model photosphere, and an empirical model chromospheres, which can be used to extrapolate the continuum to the Lyman continuum region. Given a realistic flux distribution of the early Sun, we will perform photochemical modeling of weakly reducing primitive atmospheres to determine the lifetime and photochemistry of CH4. In particular, we will make estimates of the amount of CH4 present in the prebiotic atmosphere, and estimate the atmospheric CH4 concentration during the Late Archean (2.5-3.0 b.y. ago) and determine whether it would have been sufficiently abundant to help offset reduced solar luminosity at that time. Having obtained a photochemical model, we will solve for the concentrations of greenhouse gasses and important pre-biotic molecules, and perform a detailed radiative transfer calculations to compute the UV flux reaching the surface.

  19. The Controversial Nature of the Diffuse UV Emission in Galaxies: Exploring NGC300

    NASA Astrophysics Data System (ADS)

    Thilker, David

    2014-10-01

    The wealth of data produced over the past decade by sensitive IR and wide-field UV space facilities has ushered a new era for studies of star formation in galaxies, both at the whole-galaxy and sub-galactic (<~kpc) scale. These data underscore the difficulty of using standard methods, including the dust-corrected UV light, to measure star formation within galaxies, owing to the local variations in stellar population and dust properties. The UV should be a direct tracer of young stellar populations and recent star formation, yet UV colors in the 'diffuse' interarm regions of spiral galaxies are unusually red relative to those of spiral arms, even after accounting for dust attenuation. This suggests a complex mix of moderately aged stars and dust, plus perhaps scattered light. We will unveil the origin of those UV colors with new ACS far-UV (FUV) and WFC3 near-UV (NUV) images of the nearby, prototypical spiral NGC300, which will be combined with B,V,I archival images. By exploiting the dust-insensitivity of the HST FUV-NUV color for resolved stars, we will obtain a census of both O and B stars in order to: (1) uncover the nature of the UV-emitting interarm stellar populations, while estimate the true diffuse fraction; (2) constrain the extinction law in both interarm+arm regions; (3) place UV-based SFR indicators on a secure footing for use both at low and high redshift. The angular resolution and UV capabilities of HST are crucial for this project. By directly addressing the use and limitations of UV colors to trace young stellar populations and dust attenuation in galaxies, this project maximizes the return from the large investment of HST time devoted to high-z surveys.

  20. Measuring solar UV radiation with EBT radiochromic film.

    PubMed

    Butson, Ethan T; Cheung, Tsang; Yu, Peter K N; Butson, Martin J

    2010-10-21

    Ultraviolet radiation dosimetry has been performed with the use of a radiochromic film dosimeter called Gafchromic EBT for solar radiation exposure. The film changes from a clear colour to blue colour when exposed to ultraviolet radiation and results have shown that the colour change is reproducible within ±10% at 5 kJ m(-2) UV exposure under various conditions of solar radiation. Parameters tested included changes in season (summer versus winter exposure), time of day, as well as sky conditions such as cloudy skies versus clear skies. As the radiochromic films' permanent colour change occurs in the visible wavelengths the film can be analysed with a desktop scanner with the most sensitive channel for analysis being the red component of the signal. Results showed that an exposure of 5 kJ m(-2) (approximately 1 h exposure in full sun during summer) produced an approximate 0.28 change in the net OD when analysed in reflection mode on the desktop scanner which is significant darkening. The main advantages of this film type, and thus the new EBT2 film which has replaced EBT for measurement of UV exposure, is the visible colour change and thus easy analysis using a desktop scanner, its uniformity in response and its robust physical strength for use in outside exposure situations. PMID:20858922

  1. Characterization of supersonic radiation diffusion waves

    NASA Astrophysics Data System (ADS)

    Moore, Alastair S.; Guymer, Thomas M.; Morton, John; Williams, Benjamin; Kline, John L.; Bazin, Nicholas; Bentley, Christopher; Allan, Shelly; Brent, Katie; Comley, Andrew J.; Flippo, Kirk; Cowan, Joseph; Taccetti, J. Martin; Mussack-Tamashiro, Katie; Schmidt, Derek W.; Hamilton, Christopher E.; Obrey, Kimberly; Lanier, Nicholas E.; Workman, Jonathan B.; Stevenson, R. Mark

    2015-07-01

    Supersonic and diffusive radiation flow is an important test problem for the radiative transfer models used in radiation-hydrodynamics computer codes owing to solutions being accessible via analytic and numeric methods. We present experimental results with which we compare these solutions by studying supersonic and diffusive flow in the laboratory. We present results of higher-accuracy experiments than previously possible studying radiation flow through up to 7 high-temperature mean free paths of low-density, chlorine-doped polystyrene foam and silicon dioxide aerogel contained by an Au tube. Measurements of the heat front position and absolute measurements of the x-ray emission arrival at the end of the tube are used to test numerical and analytical models. We find excellent absolute agreement with simulations provided that the opacity and the equation of state are adjusted within expected uncertainties; analytical models provide a good phenomenological match to measurements but are not in quantitative agreement due to their limited scope.

  2. Diffusion model for lightning radiative transfer

    NASA Technical Reports Server (NTRS)

    Koshak, William J.; Solakiewicz, Richard J.; Phanord, Dieudonne D.; Blakeslee, Richard J.

    1994-01-01

    A one-speed Boltzmann transport theory, with diffusion approximations, is applied to study the radiative transfer properties of lightning in optically thick thunderclouds. Near-infrared (lambda = 0.7774 micrometers) photons associated with a prominent oxygen emission triplet in the lightning spectrum are considered. Transient and spatially complex lightning radiation sources are placed inside a rectangular parallelepiped thundercloud geometry and the effects of multiple scattering are studied. The cloud is assumed to be composed of a homogeneous collection of identical spherical water droplets, each droplet a nearly conservative, anisotropic scatterer. Conceptually, we treat the thundercloud like a nuclear reactor, with photons replaced by neutrons, and utilize standard one-speed neutron diffusion techniques common in nuclear reactor analyses. Valid analytic results for the intensity distribution (expanded in spherical harmonics) are obtained for regions sufficiently far from sources. Model estimates of the arrival-time delay and pulse width broadening of lightning signals radiated from within the cloud are determined and the results are in good agreement with both experimental data and previous Monte Carlo estimates. Additional model studies of this kind will be used to study the general information content of cloud top lightning radiation signatures.

  3. UV extinction and IR emission in diffuse H2 regions

    NASA Technical Reports Server (NTRS)

    Aannestad, Per A.

    1994-01-01

    During this period, much work was spent in an attempt to use theoretical UV line indices as a basis for spectral calibration of the program stars. Five line indices are shown as functions of effective temperature and log g, calculated with the spectral synthesis programs of Kurucz. Open stars and circles are observed values from Fanelli et al., using the spectral class-effective temperature calibration of Schmidt-Kaler. We conclude that these line indices may be used to determine an effective stellar temperature, but with uncertainties of approximately a few thousand degrees. Also, for the hotter stars, theoretical line opacities are systematically low compared to observations. We have also found that Kurucz's new models appear to represent hot stars very well, even at far-UV wavelengths. This is shown in an example where two spectra of mu Col (spectral class 09.5 V) are compared to a synthetic spectrum for T(sub eff) = 33,000 K, log g = 4.0. Also shown (uppermost curve) is an empirical estimate of the intrinsic flux distribution for 09.5 V stars from Papaj, Wegner, and Krelowski.

  4. Photosynthetically active radiation (PAR) x ultraviolet radiation (UV) interact to initiate solar injury in apple

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sunburn or solar injury (SI) in apple is associated with high temperature, high visible light and ultraviolet radiation (UV). Fruit surface temperature (FST) thresholds for SI related disorders have been developed but there are no thresholds established for solar radiation. The objectives of the s...

  5. Integration and scaling of UV-B radiation effects on plants: from DNA to leaf

    PubMed Central

    Suchar, Vasile Alexandru; Robberecht, Ronald

    2015-01-01

    A process-based model integrating the effects of UV-B radiation through epidermis, cellular DNA, and its consequences to the leaf expansion was developed from key parameters in the published literature. Enhanced UV-B radiation-induced DNA damage significantly delayed cell division, resulting in significant reductions in leaf growth and development. Ambient UV-B radiation-induced DNA damage significantly reduced the leaf growth of species with high relative epidermal absorbance at longer wavelengths and average/low pyrimidine cyclobutane dimers (CPD) photorepair rates. Leaf expansion was highly dependent on the number of CPD present in the DNA, as a result of UV-B radiation dose, quantitative and qualitative absorptive properties of epidermal pigments, and repair mechanisms. Formation of pyrimidine-pyrimidone (6-4) photoproducts (6-4PP) has no effect on the leaf expansion. Repair mechanisms could not solely prevent the UV-B radiation interference with the cell division. Avoidance or effective shielding by increased or modified qualitative epidermal absorptance was required. Sustained increased UV-B radiation levels are more detrimental than short, high doses of UV-B radiation. The combination of low temperature and increased UV-B radiation was more significant in the level of UV-B radiation-induced damage than UV-B radiation alone. Slow-growing leaves were more affected by increased UV-B radiation than fast-growing leaves. PMID:26257869

  6. Integration and scaling of UV-B radiation effects on plants: from DNA to leaf.

    PubMed

    Suchar, Vasile Alexandru; Robberecht, Ronald

    2015-07-01

    A process-based model integrating the effects of UV-B radiation through epidermis, cellular DNA, and its consequences to the leaf expansion was developed from key parameters in the published literature. Enhanced UV-B radiation-induced DNA damage significantly delayed cell division, resulting in significant reductions in leaf growth and development. Ambient UV-B radiation-induced DNA damage significantly reduced the leaf growth of species with high relative epidermal absorbance at longer wavelengths and average/low pyrimidine cyclobutane dimers (CPD) photorepair rates. Leaf expansion was highly dependent on the number of CPD present in the DNA, as a result of UV-B radiation dose, quantitative and qualitative absorptive properties of epidermal pigments, and repair mechanisms. Formation of pyrimidine-pyrimidone (6-4) photoproducts (6-4PP) has no effect on the leaf expansion. Repair mechanisms could not solely prevent the UV-B radiation interference with the cell division. Avoidance or effective shielding by increased or modified qualitative epidermal absorptance was required. Sustained increased UV-B radiation levels are more detrimental than short, high doses of UV-B radiation. The combination of low temperature and increased UV-B radiation was more significant in the level of UV-B radiation-induced damage than UV-B radiation alone. Slow-growing leaves were more affected by increased UV-B radiation than fast-growing leaves. PMID:26257869

  7. Fate of Earth Microbes on Mars -- UV Radiation Effects

    NASA Technical Reports Server (NTRS)

    Cockell, Charles

    2000-01-01

    A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment. Biological action spectra for DNA inactivation are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Although the present-day martian UV flux is similar to early earth and thus may not be a limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Here calculations for loss of microbial viability on the Pathfinder and Polar lander spacecraft are presented and the effects of martian dust on loss of viability are discussed. Details of the radiative transfer model are presented.

  8. Fate of Earth Microbes on Mars: UV Radiation Effects

    NASA Technical Reports Server (NTRS)

    Cockell, Charles

    2000-01-01

    A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment. Biological action spectra for DNA inactivation are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Although the present-day martian UV flux is similar to early earth and thus may not be a limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Here calculations for loss of microbial viability on the Pathfinder and Polar lander spacecraft are presented and the effects of martian dust on loss of viability are discussed. Details of the radiative transfer model are presented.

  9. Improved Algorithms for Accurate Retrieval of UV - Visible Diffuse Attenuation Coefficients in Optically Complex, Inshore Waters

    NASA Technical Reports Server (NTRS)

    Cao, Fang; Fichot, Cedric G.; Hooker, Stanford B.; Miller, William L.

    2014-01-01

    Photochemical processes driven by high-energy ultraviolet radiation (UVR) in inshore, estuarine, and coastal waters play an important role in global bio geochemical cycles and biological systems. A key to modeling photochemical processes in these optically complex waters is an accurate description of the vertical distribution of UVR in the water column which can be obtained using the diffuse attenuation coefficients of down welling irradiance (Kd()). The Sea UV Sea UVc algorithms (Fichot et al., 2008) can accurately retrieve Kd ( 320, 340, 380,412, 443 and 490 nm) in oceanic and coastal waters using multispectral remote sensing reflectances (Rrs(), Sea WiFS bands). However, SeaUVSeaUVc algorithms are currently not optimized for use in optically complex, inshore waters, where they tend to severely underestimate Kd(). Here, a new training data set of optical properties collected in optically complex, inshore waters was used to re-parameterize the published SeaUVSeaUVc algorithms, resulting in improved Kd() retrievals for turbid, estuarine waters. Although the updated SeaUVSeaUVc algorithms perform best in optically complex waters, the published SeaUVSeaUVc models still perform well in most coastal and oceanic waters. Therefore, we propose a composite set of SeaUVSeaUVc algorithms, optimized for Kd() retrieval in almost all marine systems, ranging from oceanic to inshore waters. The composite algorithm set can retrieve Kd from ocean color with good accuracy across this wide range of water types (e.g., within 13 mean relative error for Kd(340)). A validation step using three independent, in situ data sets indicates that the composite SeaUVSeaUVc can generate accurate Kd values from 320 490 nm using satellite imagery on a global scale. Taking advantage of the inherent benefits of our statistical methods, we pooled the validation data with the training set, obtaining an optimized composite model for estimating Kd() in UV wavelengths for almost all marine waters. This

  10. Protosteller Disks Under the Influence of Winds and UV Radiation

    NASA Technical Reports Server (NTRS)

    Yorke, H. W.

    2003-01-01

    Star formation and the creation of protostellar disks generally occur in a crowded environment. Nearby young stars and protostars can influence the disks of their closets neighbors by a combination of outflows and hard radiation. The central stars themselves can have a stellar wind and may produce sufficient UV and X-ray to ultimately destroy their surrounding disks. Here we describe the results of numerical simulations of the influence that an external UV source and a central star's wind can have on its circumstellar disk. The numerical method (axial symmetry assumed) is described elsewhere. We find that protostellar disks will be destroyed on a relatively short time scale ( 10(sup 5)yr) unless they are well shielded from O-stars. Initially isotropic T-Tauri winds do not significantly influence their disks, but instead are focused toward the rotation axis by the disk wind from photoevaporation.

  11. DYE LASER SOURCE OF MONOCHROMATIC UV-B AND UV-C RADIATIONS FOR BIOLOGICAL ACTION SPECTROSCOPY

    EPA Science Inventory

    The authors have used a flashlamp driven tunable dye laser as a radiation source for observing UV-C and UV-B action spectra of two eukaryotic microorganisms. The general nature of the irradiation system and various operating parameters are described. The laser produces the high p...

  12. Epidermal screening of UV-B radiation in loblolly pine and sweetgum

    SciTech Connect

    Howells, B.W.; Ruhland, C.T.; Day, T.A.

    1995-06-01

    Seedlings of loblolly pine (Pinus taeda) and sweetgum (Liquidambar styraciflua) were grown in a greenhouse at the University of Maryland under either no UV-B radiation or daily supplemental UV-B radiation levels of 4, 8 or 11 kJ m{sup -2} of Biologically Effective. UV-B radiation. Measurements of leaf elongation, plant growth and UV-absorbing pigments were made and, at the conclusion of the growing season, measurements of UV-B screening effectiveness in different leaf age classes were made with a fiber-optic microprobe. In loblolly pine, less than 0.5 % of incident UV-B radiation was transmitted through the epidermis of fascicle needles and transmittance was less in needles that received UV-B radiation. Increases in epidermal thickness and the concentration of UV-absorbing corn may have accounted for this low transmittance. Transmission was slightly greater (about 1%) in primary needles, possibly due to a thinner epidermis. In contrast, in sweetgum, epidermal transmittance ranged from about 20% in leaves not preconditioned to UV-B exposure, to about 12% in leaves grown under UV-B radiation. These results suggest that any deleterious effects of UV-B radiation may be anticipated to be greatest in early stages of leaf development and in primary needles of conifers, before UV-B penetration is reduced by increases in epidermal thickness and UV-absorbing compounds.

  13. Improving radiation data quality of USDA UV-B monitoring and research program and evaluating UV decomposition in DayCent and its ecological impacts

    NASA Astrophysics Data System (ADS)

    Chen, Maosi

    from an improved cloud screening algorithm that utilizes an iterative rejection of cloudy points based on a decreasing tolerance of unstable optical depth behavior when calibration information is unknown. A MODTRAN radiative transfer model simulation showed the new cloud screening algorithm was capable of screening cloudy points while retaining clear-sky points. The comparison results showed that the cloud-free points determined by the new cloud screening algorithm generated significantly (56%) more and unbiased Langley offset voltages (VLOs) for both partly cloudy days and sunny days at two testing sites, Hawaii and Florida. The V¬LOs are proportional to the radiometric sensitivity. The stability of the calibration is also improved by the development of a two-stage reference channel calibration method for collocated UV-MFRSR and MFRSR instruments. Special channels where aerosol is the only contributor to total optical depth (TOD) variation (e.g. 368-nm channel) were selected and the radiative transfer model (MODTRAN) used to calculate direct normal and diffuse horizontal ratios which were used to evaluate the stability of TOD in cloud-free points. The spectral dependence of atmospheric constituents' optical properties and previously calibrated channels were used to find stable TOD points and perform Langley calibration at spectrally adjacent channels. The test of this method on the UV-B program site at Homestead, Florida (FL02) showed that the new method generated more clustered and abundant VLOs at all (UV-) MFRSR channels and potentially improved the accuracy by 2-4% at most channels and over 10% at 300-nm and 305-nm channels. In the second major part of this work, I calibrated the DayCent-UV model with ecosystem variables (e.g. soil water, live biomass), allowed maximum photodecay rate to vary with litter's initial lignin fraction in the model, and validated the optimized model with LIDET observation of remaining carbon and nitrogen at three semi-arid sites. I

  14. Penetration of diffuse ultraviolet radiation into interstellar clouds

    SciTech Connect

    Flannery, B.P.; Roberge, W.; Rybicki, G.B.

    1980-03-01

    We show that the solution of the transfer equation appropriate for models of the penetration of diffuse UV radiation into interstellar clouds, subject to attenuation by coherent, nonconservative, anisotropic scattering from grains, can be expressed analytically, with arbitrary accuracy, by means of the spherical harmonics method. Models of plane-parallel and homogeneous spherical clouds are given as functions of three parameters: tau/sub c/ the central optical depth, ..omega.. the single scattering albedo, and g the parameter in the Henyey-Greenstein phase function. These models qualitatively confirm the results of earlier Monte Carlo simulations of dust scattering, but reveal quantitative discrepancies: the earlier results overestimated the actual mean intensity, often by more than an order of magnitude.

  15. Adaptive Implicit Non-Equilibrium Radiation Diffusion

    SciTech Connect

    Philip, Bobby; Wang, Zhen; Berrill, Mark A; Rodriguez Rodriguez, Manuel; Pernice, Michael

    2013-01-01

    We describe methods for accurate and efficient long term time integra- tion of non-equilibrium radiation diffusion systems: implicit time integration for effi- cient long term time integration of stiff multiphysics systems, local control theory based step size control to minimize the required global number of time steps while control- ling accuracy, dynamic 3D adaptive mesh refinement (AMR) to minimize memory and computational costs, Jacobian Free Newton-Krylov methods on AMR grids for efficient nonlinear solution, and optimal multilevel preconditioner components that provide level independent solver convergence.

  16. Antiradiation UV Vaccine: UV Radiation, Biological effects, lesions and medical management - immune-therapy and immune-protection.

    NASA Astrophysics Data System (ADS)

    Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

    Key Words: Ultraviolet radiation,Standard Erythema Dose(SED), Minimal Erythema Dose(MED), Sun Burns, Solar Dermatitis, Sun Burned Disease, DNA Damage,Cell Damage, Antiradiation UV Vaccine, Immune-Prophylaxis of Sun Burned Diseases, Immune-Prophylaxis of Sun Burns, Immune-Therapy of Sun-Burned Disease and Sun Burns,Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC), Toxic Epidermal Necrolysis(TEN). Introduction: High doses of UV generated by solar source and artificial sources create an exposure of mammals and other species which can lead to ultraviolet(UV)radiation- associated disease (including erythema, epilation, keratitis, etc.). UV radiation belongs to the non-ionizing part of the electromagnetic spectrum and ranges between 100 nm and 400 nm with 100 nm having been chosen arbitrarily as the boundary between non-ionizing and ionizing radiation, however EMR is a spectrum and UV can produce molecular ionization. UV radiation is conventionally categorized into 3 areas: UV-A (>315-400 nm),UV-B (>280-315 nm)and UV-C (>100-280 nm) [IARC,Working Group Reports,2005] An important consequence of stratospheric ozone depletion is the increased transmission of solar ultraviolet (UV)radiation to the Earth's lower atmosphere and surface. Stratospheric ozone levels have been falling, in certain areas, for the past several decades, so current surface ultraviolet-B (UV-B) radiation levels are thought to be close to their modern day maximum. [S.Madronich et al.1998] Overexposure of ultraviolet radiation a major cause of skin cancer including basal cell carcinoma (BCC), squamous cell carcinoma (SCC) { collectively referred to as “non-melanoma" skin cancer (NMSC) and melanoma as well, with skin cancers being the most common cancer in North America. [Armstrong et al. 1993, Gallagher et al. 2005] Methods and Experimental Design: Our experiments and testing of a novel UV “Antiradiation Vaccine” have employed a wide variety of laboratory animals which include : Chinchilla

  17. Automatic actinometric system for diffuse radiation measurement

    NASA Astrophysics Data System (ADS)

    Litwiniuk, Agnieszka; Zajkowski, Maciej

    2015-09-01

    Actinometric station is using for measuring solar of radiation. The results are helpful in determining the optimal position of solar panels relative to the Sun, especially in today's world, when the energy coming from the Sun and other alternative sources of energy become more and more popular. Polish climate does not provide as much energy as in countries in southern Europe, but it is possible to increase the amount of energy produced by appropriate arrangement of photovoltaic panels. There is the possibility of forecasting the amount of produced energy, the cost-effectiveness and profitability of photovoltaic installations. This implies considerable development opportunities for domestic photovoltaic power plants. This article presents description of actinometric system for diffuse radiation measurement, which is equipped with pyranometer - thermopile temperature sensor, amplifier AD620, AD Converter ADS1110, microcontroller Atmega 16, SD card, GPS module and LCD screen.

  18. The influence of UV radiation on protistan evolution

    NASA Technical Reports Server (NTRS)

    Rothschild, L. J.

    1999-01-01

    Ultraviolet radiation has provided an evolutionary challenge to life on Earth. Recent increases in surficial ultraviolet B fluxes have focused attention on the role of UV radiation in protistan ecology, cancer, and DNA damage. Exploiting this new wealth of data, I examine the possibility that ultraviolet radiation may have played a significant role in the evolution of the first eukaryotes, that is, protists. Protists probably arose well before the formation of a significant ozone shield, and thus were probably subjected to substantial ultraviolet A, ultraviolet B, and ultraviolet C fluxes early in their evolution. Evolution consists of the generation of heritable variations and the subsequent selection of these variants. Ultraviolet radiation has played a role both as a mutagen and as a selective agent. In its role as a mutagen, it may have been crucial in the origin of sex and as a driver of molecular evolution. As a selective agent, its influence has been broad. Discussed in this paper are the influence of ultraviolet radiation on biogeography, photosynthesis, and desiccation resistance.

  19. EFFECTS OF UV RADIATION ON PLANTS IN THE TRANSITION REGION TO BLUE LIGHT

    EPA Science Inventory

    Generalizations concerning the effects of UV radiation on plants are easy targets of criticism and certainly subject to considerable qualification. This review generalizes rather than presents a detailed compilation of available literature. Wavebands within the UV spectrum have b...

  20. Solar UV Radiation and the Origin of Life On Earth

    NASA Technical Reports Server (NTRS)

    Heap, S. R.; Lanz, T.; Hubeny, I.; Gaidos, E.; Oegerle, William R. (Technical Monitor)

    2002-01-01

    We have embarked on a program aimed at understanding the atmosphere of the early Earth, because of its importance as a greenhouse, radiation shield and energy source for life. Here, we give a progress report on the first phase of this program to establish the UV radiation from the early Sun. We have obtained ultraviolet spectra (STIS, FUSE, EUVE) of carefully selected nearby, young solar-type stars, which act as surrogates for the early Sun We are making detailed non-LTE analyses of the spectra and constructing models of their photospheres + chromospheres. Once validated, these models will allow us to extrapolate our theoretical spectra to other metallicities and to unobserved spectral regions.

  1. Solar UV Radiation and the Origin of Life on Earth

    NASA Technical Reports Server (NTRS)

    Heap, S. R.; Gaidos, E.; Hubeny, I.; Lanz, T. M.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We have embarked on a program aimed at understanding the atmosphere of the early Earth, because of its importance as a greenhouse, radiation shield, and energy source for life. Here, we give a progress report on the first phase of this program: to establish the UV radiation from the early Sun. We are presently obtaining ultraviolet spectra (STIS, FUSE, EUVE) of carefully selected nearby, young solar-type stars, which act as surrogates for the early Sun. We are currently making detailed non-LTE analyses of the spectra and constructing models of their photospheres + chromospheres. once validated, these models will allow us to extrapolate our theoretical spectra to unobserved spectral regions, and to proceed to the next step: to develop photochemical models of the pre-biotic and Archean atmosphere of the Earth.

  2. Gas phase radiative effects in diffusion flames

    NASA Astrophysics Data System (ADS)

    Bedir, Hasan

    Several radiation models are evaluated for a stagnation point diffusion flame of a solid fuel in terms of accuracy and computational time. Narrowband, wideband, spectral line weighted sum of gray gases (SLWSGG), and gray gas models are included in the comparison. Radiative heat flux predictions by the nongray narrowband, wideband, and SLWSGG models are found to be in good agreement with each other, whereas the gray gas models are found to be inaccurate. The narrowband model, the most complex among the models evaluated, is then applied first to a solid fuel and second to a pure gaseous diffusion flame. A polymethylmethacrylate (PMMA) diffusion flame in a stagnation point geometry is solved with the narrowband model with COsb2, Hsb2O, and MMA vapor included in participating species. A detailed account of the emission and absorption from these species as well as the radiative heat fluxes are given as a function of the stretch rate. It is found that at low stretch rate the importance of radiation is increased due to an increase in the optical thickness, and a decrease in the conductive heat flux. Results show that COsb2 is the biggest emitter and absorber in the flame, MMA vapor is the second and Hsb2O is the least important. A pure gaseous flame in an opposed jet configuration is solved with the narrowband radiation model with CO as the fuel, and Osb2 as the oxidizer. Detailed. chemical kinetics and transport are incorporated into the combustion model with the use of the CHEMKIN and TRANSPORT software packages. The governing equations are solved with a modified version of the OPPDIF code. Dry and wet CO flames as well as COsb2 dilution are studied. Comparison of the results with and without the consideration of radiation reveals that the radiation is important for the whole flammable range of dry CO flames and for the low stretch rates of wet flames. Without the consideration of radiation the temperature and the species mole fractions (especially of minor species

  3. A radiating shock evaluated using Implicit Monte Carlo Diffusion

    SciTech Connect

    Cleveland, M.; Gentile, N.

    2013-07-01

    Implicit Monte Carlo [1] (IMC) has been shown to be very expensive when used to evaluate a radiation field in opaque media. Implicit Monte Carlo Diffusion (IMD) [2], which evaluates a spatial discretized diffusion equation using a Monte Carlo algorithm, can be used to reduce the cost of evaluating the radiation field in opaque media [2]. This work couples IMD to the hydrodynamics equations to evaluate opaque diffusive radiating shocks. The Lowrie semi-analytic diffusive radiating shock benchmark[a] is used to verify our implementation of the coupled system of equations. (authors)

  4. The Response of Human Skin Commensal Bacteria as a Reflection of UV Radiation: UV-B Decreases Porphyrin Production

    PubMed Central

    Wang, Yanhan; Zhu, Wenhong; Shu, Muya; Jiang, Yong; Gallo, Richard L.; Liu, Yu-Tsueng; Huang, Chun-Ming

    2012-01-01

    Recent global radiation fears reflect the urgent need for a new modality that can simply determine if people are in a radiation risk of developing cancer and other illnesses. Ultraviolet (UV) radiation has been thought to be the major risk factor for most skin cancers. Although various biomarkers derived from the responses of human cells have been revealed, detection of these biomarkers is cumbersome, probably requires taking live human tissues, and varies significantly depending on human immune status. Here we hypothesize that the reaction of Propionibacterium acnes (P. acnes), a human resident skin commensal, to UV radiation can serve as early surrogate markers for radiation risk because the bacteria are immediately responsive to radiation. In addition, the bacteria can be readily accessible and exposed to the same field of radiation as human body. To test our hypothesis, P. acnes was exposed to UV-B radiation. The production of porphyrins in P. acnes was significantly reduced with increasing doses of UV-B. The porphyrin reduction can be detected in both P. acnes and human skin bacterial isolates. Exposure of UV-B to P. acnes- inoculated mice led to a significant decrease in porphyrin production in a single colony of P. acnes and simultaneously induced the formation of cyclobutane pyrimidine dimers (CPD) in the epidermal layers of mouse skin. Mass spectrometric analysis via a linear trap quadrupole (LTQ)-Orbitrap XL showed that five peptides including an internal peptide (THLPTGIVVSCQNER) of a peptide chain release factor 2 (RF2) were oxidized by UV-B. Seven peptides including three internal peptides of 60 kDa chaperonin 1 were de-oxidized by UV-B. When compared to UV-B, gamma radiation also decreased the porphyrin production of P. acnes in a dose-dependent manner, but induced a different signature of protein oxidation/de-oxidation. We highlight that uncovering response of skin microbiome to radiation will facilitate the development of pre-symptomatic diagnosis

  5. Spectrometer system for diffuse extreme ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Labov, Simon E.

    1989-01-01

    A unique grazing incidence spectrometer system has been designed to study diffuse line emission between 80 and 650 A with 10-30 A resolution. The minimum detectable emission line strength during a 5-min observation ranges from 100-2000 ph/sq cm sec str. The instrument uses mechanically ruled reflection gratings placed in front of a linear array of mirrors. These mirrors focus the spectral image on microchannel plate detectors located behind thin filters. The field of view is 40 min of arc by 15 deg, and there is no spatial imaging. This instrument has been fabricated, calibrated, and successfully flown on a sounding rocket to observe the astronomical background radiation.

  6. Bioequivalent UV detectors based on cholesteric liquid crystals: effects of spectral composition and quantitative account for intensity of UV radiation

    NASA Astrophysics Data System (ADS)

    Lisetski, Longin N.; Panikarskaya, Valentina D.; Kasyan, Natalya A.; Grishchenko, Leonid V.; Terenetskaya, Irina P.

    2005-11-01

    Response of cholesteric sensor materials to biologically active UV radiation has been studied. The sensor mixture comprised a cholesteric liquid crystalline matrix doped with provitamin D, and changes in the maximum selective reflection wavelength λ max caused by the photochemical reaction of provitamin D --> vitamin D transformation were recorded. Using a UV source (DRT-240 lamp) calibrated accounting for the specific irradiation geometry, λ max shifts were obtained as function of UV illuminance dose (in J/cm2). Using a set of optical filters cutting off specified parts of the provitamin D absorption spectrum, effects of the spectral composition of UV radiation upon the response characteristics of sensor were determined. The results obtained support our earlier considerations of the developed sensor material as "bioequivalent".

  7. Antiradiation UV Vaccine: UV Radiation, Biological effects, lesions and medical management - immune-therapy and immune-protection.

    NASA Astrophysics Data System (ADS)

    Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

    Key Words: Ultraviolet radiation,Standard Erythema Dose(SED), Minimal Erythema Dose(MED), Sun Burns, Solar Dermatitis, Sun Burned Disease, DNA Damage,Cell Damage, Antiradiation UV Vaccine, Immune-Prophylaxis of Sun Burned Diseases, Immune-Prophylaxis of Sun Burns, Immune-Therapy of Sun-Burned Disease and Sun Burns,Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC), Toxic Epidermal Necrolysis(TEN). Introduction: High doses of UV generated by solar source and artificial sources create an exposure of mammals and other species which can lead to ultraviolet(UV)radiation- associated disease (including erythema, epilation, keratitis, etc.). UV radiation belongs to the non-ionizing part of the electromagnetic spectrum and ranges between 100 nm and 400 nm with 100 nm having been chosen arbitrarily as the boundary between non-ionizing and ionizing radiation, however EMR is a spectrum and UV can produce molecular ionization. UV radiation is conventionally categorized into 3 areas: UV-A (>315-400 nm),UV-B (>280-315 nm)and UV-C (>100-280 nm) [IARC,Working Group Reports,2005] An important consequence of stratospheric ozone depletion is the increased transmission of solar ultraviolet (UV)radiation to the Earth's lower atmosphere and surface. Stratospheric ozone levels have been falling, in certain areas, for the past several decades, so current surface ultraviolet-B (UV-B) radiation levels are thought to be close to their modern day maximum. [S.Madronich et al.1998] Overexposure of ultraviolet radiation a major cause of skin cancer including basal cell carcinoma (BCC), squamous cell carcinoma (SCC) { collectively referred to as “non-melanoma" skin cancer (NMSC) and melanoma as well, with skin cancers being the most common cancer in North America. [Armstrong et al. 1993, Gallagher et al. 2005] Methods and Experimental Design: Our experiments and testing of a novel UV “Antiradiation Vaccine” have employed a wide variety of laboratory animals which include : Chinchilla

  8. UV radiation and organic matter composition shape bacterial functional diversity in sediments

    PubMed Central

    Hunting, Ellard R.; White, Christopher M.; van Gemert, Maarten; Mes, Daan; Stam, Eva; van, Harm G.; der Geest; Kraak, Michiel H. S.; Admiraal, Wim

    2013-01-01

    UV radiation and organic matter (OM) composition are known to influence the species composition of bacterioplankton communities. Potential effects of UV radiation on bacterial communities residing in sediments remain completely unexplored to date. However, it has been demonstrated that UV radiation can reach the bottom of shallow waters and wetlands and alter the OM composition of the sediment, suggesting that UV radiation may be more important for sediment bacteria than previously anticipated. It is hypothesized here that exposure of shallow OM-containing sediments to UV radiation induces OM source-dependant shifts in the functional composition of sediment bacterial communities. This study therefore investigated the combined influence of both UV radiation and OM composition on bacterial functional diversity in laboratory sediments. Two different OM sources, labile and recalcitrant OM, were used and metabolic diversity was measured with Biolog GN. Radiation exerted strong negative effects on the metabolic diversity in the treatments containing recalcitrant OM, more than in treatments containing labile OM. The functional composition of the bacterial community also differed significantly between the treatments. Our findings demonstrate that a combined effect of UV radiation and OM composition shapes the functional composition of microbial communities developing in sediments, hinting that UV radiation may act as an important sorting mechanism for bacterial communities and driver for bacterial functioning in shallow waters and wetlands. PMID:24194736

  9. UV-laser-based longitudinal illuminated diffuser (LID) incorporating diffractive and Lambertian reflectance for the disinfection of beverages

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd

    2010-08-01

    A novel laser beam shaping system was designed to demonstrate the potential of using high power UV laser sources for large scale disinfection of liquids used in the production of food products, such as juices, beer, milk and other beverage types. The design incorporates a patented assembly of optical components including a diffractive beam splitting/shaping element and a faceted pyramidal or conically shaped Lambertian diffuser made from a compression molded PTFE compounds. When properly sintered to an appropriate density, as an example between 1.10 and 1.40 grams per cubic centimeter, the compressed PTFE compounds show a ~99% reflectance at wavelengths ranging from 300 nm to 1500 nm, and a ~98.5% refection of wavelengths from 250 nm to 2000 nm [1]. The unique diffuser configuration also benefits from the fact that the PTFE compounds do not degrade when exposed to ultraviolet radiation as do barium sulfate materials and silver or aluminized mirror coatings [2]. These components are contained within a hermetically sealed quartz tube. Once assembled a laser beam is directed through one end of the tube. This window takes the form of a computer generated diffractive splitter or other diffractive shaper element to split the laser beam into a series of spot beamlets, circular rings or other geometric shapes. As each of the split beamlets or rings cascade downward, they illuminate various points along the tapered PTFE cone or faceted pyramidal form. As they strike the surface they each diffuse in a Lambertian reflectance pattern creating a pseudo-uniform circumferential illuminator along the length of the quartz tube enclosing the assembly. The compact tubular structure termed Longitudinal Illuminated Diffuser (LID) provides a unique UV disinfection source that can be placed within a centrifugal reactor or a pipe based reactor chamber. This paper will review the overall design principle, key component design parameters, preliminary analytic and bench operational testing

  10. Bystander effect induced by UV radiation; why should we be interested?

    PubMed

    Widel, Maria

    2012-01-01

    The bystander effect, whose essence is an interaction of cells directly subjected to radiation with adjacent non-subjected cells, via molecular signals, is an important component of ionizing radiation action. However, knowledge of the bystander effect in the case of ultraviolet (UV) radiation is quite limited. Reactive oxygen and nitrogen species generated by UV in exposed cells induce bystander effects in non-exposed cells, such as reduction in clonogenic cell survival and delayed cell death, oxidative DNA damage and gene mutations, induction of micronuclei, lipid peroxidation and apoptosis. Although the bystander effect after UV radiation has been recognized in cell culture systems, its occurrence in vivo has not been studied. However, solar UV radiation, which is the main source of UV in the environment, may induce in human dermal tissue an inflammatory response and immune suppression, events which can be considered as bystander effects of UV radiation. The oxidative damage to DNA, genomic instability and the inflammatory response may lead to carcinogenesis. UV radiation is considered one of the important etiologic factors for skin cancers, basal- and squamous-cell carcinomas and malignant melanoma. Based on the mechanisms of actions it seems that the UV-induced bystander effect can have some impact on skin damage (carcinogenesis?), and probably on cells of other tissues. The paper reviews the existing data about the UV-induced bystander effect and discusses a possible implication of this phenomenon for health risk.  PMID:23175338

  11. Characterization of Actin Filament Dynamics during Mitosis in Wheat Protoplasts under UV-B Radiation

    PubMed Central

    Chen, Huize; Han, Rong

    2016-01-01

    Enhanced ultraviolet-B (UV-B) radiation is caused by the thinning ozone and affects photosynthesis and crop yield. Recently, UV-B radiation has been considered as an environmental signal that regulates plant growth. Elucidating the downstream effectors in UV-B-triggered pathways is of particular interest. Previous studies have shown that actin filaments (AFs) play many roles during cell physiological processes. However, the underlying response of AFs to UV-B radiation remains unclear. In this study, wheat protoplasts were isolated from 7-d-old leaves. The dynamics of AFs during mitosis were observed under different treatments. The protoplasts were treated with UV-B radiation, cytochalasin B (CB) and jasplakinolide (JAS). Ph-FITC labelling results revealed typical actin filament structures in the control group; AFs were rearranged under UV-B radiation. AFs polymerized into bundles during interphase, the preprophase band (PPB) structure was destroyed during prophase, and the AFs gathered into plaques during metaphase in response to UV-B radiation. During anaphase and telophase, the distribution of AFs was dispersed. Pharmacologic experiments revealed that CB induced apoptosis and JAS induced nuclear division without cytokinesis in wheat protoplasts. These results indicated that AFs respond to UV-B radiation during mitosis, supplying evidence of UV-B signal transduction in plants. PMID:26823006

  12. Characterization of Actin Filament Dynamics during Mitosis in Wheat Protoplasts under UV-B Radiation.

    PubMed

    Chen, Huize; Han, Rong

    2016-01-01

    Enhanced ultraviolet-B (UV-B) radiation is caused by the thinning ozone and affects photosynthesis and crop yield. Recently, UV-B radiation has been considered as an environmental signal that regulates plant growth. Elucidating the downstream effectors in UV-B-triggered pathways is of particular interest. Previous studies have shown that actin filaments (AFs) play many roles during cell physiological processes. However, the underlying response of AFs to UV-B radiation remains unclear. In this study, wheat protoplasts were isolated from 7-d-old leaves. The dynamics of AFs during mitosis were observed under different treatments. The protoplasts were treated with UV-B radiation, cytochalasin B (CB) and jasplakinolide (JAS). Ph-FITC labelling results revealed typical actin filament structures in the control group; AFs were rearranged under UV-B radiation. AFs polymerized into bundles during interphase, the preprophase band (PPB) structure was destroyed during prophase, and the AFs gathered into plaques during metaphase in response to UV-B radiation. During anaphase and telophase, the distribution of AFs was dispersed. Pharmacologic experiments revealed that CB induced apoptosis and JAS induced nuclear division without cytokinesis in wheat protoplasts. These results indicated that AFs respond to UV-B radiation during mitosis, supplying evidence of UV-B signal transduction in plants. PMID:26823006

  13. Optical Protection Filters for Harmful Laser Beams and UV Radiation

    SciTech Connect

    Azim M, Osama A.

    2007-02-14

    Due to the rapid growth of radiation protection applications in various devices and instruments, it is essential to use suitable filters for eye protection of the personal working in the radiation field. Different protection filters were produced to protect from four laser beam wavelengths (at 532nm, 632.8nm, 694nm and 1064nm) and block three UV bands (UVA, UVB, and UVC). The design structure of the required dielectric multilayer filters used optical thin film technology. The computer analyses of the multilayer filter formulas were prepared using Macleod Software for the production filter processes. The deposition technique was achieved on optical substrates (Glass BK-7 and Infrasil 301) by dielectric material combinations including Dralo (mixture of oxides TiO2/Al2O3), and Lima (mixture of oxides SiO2/Al2O3); deposition by an electron beam gun. The output transmittance curves for both theoretical and experimental values of all filters are presented. To validate the suitability for use in a 'real world', rather than laboratory test application, full environmental assessment was also carried out. These filters exhibited high endurance after exposing them to the durability tests (adhesion, abrasion resistance and humidity) according to military standards MIL-C-675C and MIL-C-48497A.

  14. Synergism between UV-B radiation and pathogen magnifies amphibian embryo mortality in nature

    SciTech Connect

    Kiesecker, J.M.; Blaustein, R.

    1995-11-21

    Previous research has shown that amphibians have differential sensitivity to ultraviolet-B (UV-B) radiation. In some species, ambient levels of UV-B radiation cause embryonic mortality in nature. The detrimental effects of UV-B alone or with other agents may ultimately affect amphibians at the population level. Here, we experimentally demonstrate a synergistic effect between UV-B radiation and a pathogenic fungus in the field that increases the mortality of amphibian embryos compared with either factor alone. Studies investigating single factors for causes of amphibian egg mortality or population declines may not reveal the complex factors involved in declines.

  15. Divergences in the response to ultraviolet radiation between polar and non-polar ciliated protozoa: UV radiation effects in Euplotes.

    PubMed

    Di Giuseppe, Graziano; Cervia, Davide; Vallesi, Adriana

    2012-02-01

    Ultraviolet (UV) radiation has detrimental effects on marine ecosystems, in particular in the polar regions where stratospheric ozone reduction causes higher levels of solar radiation. We analyzed two polar species of Euplotes, Euplotes focardii and Euplotes nobilii, for the sensitivity to UV radiation in comparison with two akin species from mid-latitude and tropical waters. Results showed that they face UV radiation much more efficiently than the non-polar species by adopting alternative strategies that most likely reflect different times of colonization of the polar waters. While E. focardii, which is endemic to the Antarctic, survives for longer exposed to UV radiation, E. nobilii, which inhabits both the Antarctic and Arctic, recovers faster from UV-induced damage. PMID:21904954

  16. Effects of Solar UV Radiation and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

    EPA Science Inventory

    Solar UV radiation, climate and other drivers of global change are undergoing significant changes and models forecast that these changes will continue for the remainder of this century. Here we assess the effects of solar UV radiation on biogeochemical cycles and the interactions...

  17. Biologically weighted measurement of UV radiation in space and on earth with the biofilm technique

    NASA Astrophysics Data System (ADS)

    Rettberg, P.; Horneck, G.

    Biological dosimetry has provided experimental proof of the high sensitivity of the biologically effective UVB doses to changes in atmospheric ozone and has thereby confirmed the predictions from model calculations. The biological UV dosimeter 'biofilm' whose sensitivity is based on dried spores of B. subtilis as UV target weights the incident UV radiation according to its DNA damaging potential. Biofilm dosimetry was applicated in space experiments as well as in use in remote areas on Earth. Examples are long-term UV measurements in Antarctica, measurements of diurnal UV profiles parallel in time at different locations in Europe, continuous UV measurements in the frame of the German UV measurement network and personal UV dosimetry. In space biofilms were used to determine the biological efficiency of the extraterrestrial solar UV, to simulate the effects of decreasing ozone concentrations and to determine the interaction of UVB and vitamin D production of cosmonauts in the MIR station.

  18. Biologically weighted measurement of UV radiation in space and on Earth with the biofilm technique.

    PubMed

    Rettberg, P; Horneck, G

    2000-01-01

    Biological dosimetry has provided experimental proof of the high sensitivity of the biologically effective UVB doses to changes in atmospheric ozone and has thereby confirmed the predictions from model calculations. The biological UV dosimeter 'biofilm' whose sensitivity is based on dried spores of B. subtilis as UV target weights the incident UV radiation according to its DNA damaging potential. Biofilm dosimetry was applicated in space experiments as well as in use in remote areas on Earth. Examples are long-term UV measurements in Antarctica, measurements of diurnal UV profiles parallel in time at different locations in Europe, continuous UV measurements in the frame of the German UV measurement network and personal UV dosimetry. In space biofilms were used to determine the biological efficiency of the extraterrestrial solar UV, to simulate the effects of decreasing ozone concentrations and to determine the interaction of UVB and vitamin D production of cosmonauts in the MIR station. PMID:12038486

  19. LEAF UV OPTICAL PROPERTIES OF 'RUMEX PATIENTIA' L. AND 'RUMEX OBTUSIFOLIUS L. IN REGARD TO A PROTECTIVE MECHANISM AGAINST SOLAR UV-B RADIATION INJURY

    EPA Science Inventory

    Effective UV attenuation in the outer leaf layers may represent an important protective mechanism against potentially damaging solar UV-B radiation. Epidermal optical properties for Rumex patientia and Rumex obtusifolius were examined on field collected and greenhouse grown plant...

  20. Interactive effects of solar UV radiation and climate change on biogeochemical cycling.

    PubMed

    Zepp, R G; Erickson, D J; Paul, N D; Sulzberger, B

    2007-03-01

    This report assesses research on the interactions of UV radiation (280-400 nm) and global climate change with global biogeochemical cycles at the Earth's surface. The effects of UV-B (280-315 nm), which are dependent on the stratospheric ozone layer, on biogeochemical cycles are often linked to concurrent exposure to UV-A radiation (315-400 nm), which is influenced by global climate change. These interactions involving UV radiation (the combination of UV-B and UV-A) are central to the prediction and evaluation of future Earth environmental conditions. There is increasing evidence that elevated UV-B radiation has significant effects on the terrestrial biosphere with implications for the cycling of carbon, nitrogen and other elements. The cycling of carbon and inorganic nutrients such as nitrogen can be affected by UV-B-mediated changes in communities of soil organisms, probably due to the effects of UV-B radiation on plant root exudation and/or the chemistry of dead plant material falling to the soil. In arid environments direct photodegradation can play a major role in the decay of plant litter, and UV-B radiation is responsible for a significant part of this photodegradation. UV-B radiation strongly influences aquatic carbon, nitrogen, sulfur and metals cycling that affect a wide range of life processes. UV-B radiation changes the biological availability of dissolved organic matter to microorganisms, and accelerates its transformation into dissolved inorganic carbon and nitrogen, including carbon dioxide and ammonium. The coloured part of dissolved organic matter (CDOM) controls the penetration of UV radiation into water bodies, but CDOM is also photodegraded by solar UV radiation. Changes in CDOM influence the penetration of UV radiation into water bodies with major consequences for aquatic biogeochemical processes. Changes in aquatic primary productivity and decomposition due to climate-related changes in circulation and nutrient supply occur concurrently with

  1. Acclimation of a marine diatom, Chaetoceros gracilis, to ambient levels of UV radiation

    SciTech Connect

    Hazzard, C.E.; Kinzie, R.A. III ); Taguchi, S. )

    1990-01-09

    Semi-continuous cultures of Chaetoceros gracilis were maintained in two ultraviolet (UV) exposure treatments for 23 days in natural sunlight. In one treatment algae received only wavelengths above 380 nm, while the second received total ambient UV. After acclimation, samples from both treatments were incubated in quartz bottles under ambient solar radiation. At the onset of the experiment, the cultures which were grown under reduced UV were growing 44.6% faster than the UV exposed cultures and contained 39.4% more chlorophyll/cell. After 24 hours of exposure to ambient UV, the growth rate for the reduced UV cultures decreased by 635% while that of the UV exposed cultures remained unchanged. Total productivity/chl a was significantly lower in the UV shaded cultures throughout the 24 hour period, while the rate of carbon release though dark respiration was significantly greater in the cultures which had been acclimated in ambient UV conditions. Relative amounts of carbon incorporation into lipids, intermediate weight compounds, polysaccharides and nucleic acids, and protein were significantly different between the treatments in all but the polysaccharide fraction. UV shaded cultures incorporated a higher percentage of fixed carbon into protein and lipid than UV exposed cultures while incorporating less into the intermediate weight compounds. This study suggests that naturally occurring Chaetoceros gracilis cells are able to resist the inhibitory effects of ambient UV radiation by a protective mechanism which is initiated by the presence of UV.

  2. Diffuse galactic annihilation radiation from supernova nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Higdon, J. C.

    1985-01-01

    The propagation of MeV positrons in the outer ejecta of type I supernovae was investigated. It was found that the positrons created at times of approx 100 days propagated along magnetic field lines in the outer ejecta without any appreciable pitch-angle scattering or excitation of hydromagnetic waves. The lack of significant pitch-angle scattering is well consistent with models of wave excitation and scattering by resonant interactions. This occurs because time periods to scatter the particles or to excite waves are significantly longer than escape times. Thus it is expected that, when positrons are not coupled to the ejecta by Coulomb collisions, they escape from the relatively cold, dense ejecta and reside predominantly in the tenuous, hotter, shock-heated interstellar gas. In the tenuous shock-heated gas the positron lifetime against annihilation is much greater than lifetimes in the dense ejectra. Thus the production of steady-state diffuse annihilation radiation by some fraction of these escaped positrons seems probable.

  3. Generation of tumor-specific transplantation antigens by UV radiation can occur independently of neoplastic transformation.

    PubMed

    Hostetler, L W; Ananthaswamy, H N; Kripke, M L

    1986-10-15

    The purpose of this study was to determine whether the UV-associated antigens present on tumors induced in mice by chronic UV irradiation could be induced by in vitro irradiation of cells that were already tumorigenic, or whether their occurrence was associated with the primary neoplastic transformation event. Cells of a nonantigenic, spontaneous fibrosarcoma cell line were exposed to UV radiation in vitro, were cloned, and were tested for antigenic properties. A large number of the clones obtained after UV irradiation of the fibrosarcoma cells were highly antigenic (20 of 39), whereas clones derived from unirradiated cultures were not (0 of 10). The antigenic variants did not induce cross-protection among themselves, but induced only variant-specific immunity in vivo. Several antigenic variants were tested for susceptibility to the action of UV-induced suppressor cells, which seem to recognize a common determinant shared among UV-induced tumors. The variants tested were indeed subject to the activity of the UV-induced suppressor lymphocytes. These results demonstrate that the unique antigenic properties exhibited by UV-induced murine skin cancers are also exhibited by cells exposed to UV radiation in vitro. In addition, they imply that the UV-associated antigens arise as a consequence of exposing cells to UV radiation and that they can occur independently of an initial neoplastic transformation event. PMID:3760572

  4. Short-term responses of barley to changes in ambient levels of UV-B radiation and their role in UV protection

    NASA Astrophysics Data System (ADS)

    Sullivan, Joseph H.; Gitz, Dennis C.; Stapleton, Ann E.; Gao, Wei; Slusser, James R.

    2003-06-01

    While many studies have evaluated the chronic effects of exposure to enhanced levels of UV-B radiation on plants very few studies have evaluated the implications of plant development within a background of fluctuating levels of UV-B radiation. Much interest and concern surround the issue of stratospheric ozone depletion and concurrent increases in UV-B radiation and this remains a concern. However, variation in UV-B levels on a daily basis is largely due to cloud cover and tropospheric air quality as well as possible effects of fluctuations in the total ozone column. Therefore the importance of the effects of short-term changes in UV-B radiation is not predicated on the assumption of continued ozone destruction. In this study we evaluated to change in foliar phenolic composition in barley and the consequences of changes in these putative protection compounds on subsequent sensitivity to UV-V radiation. The UV-B exposure levels ranges from less than 1 to nearly 8 kJ m-2 of biologically weighted UV-B radiation. Barley plants that developed under height ambient levels of UV-B radiation had higher levels of phenolics than control plants grown under the same conditions except with UV-B excluded. Those plants with higher phenolic content show some degree of increased protection from subsequent levels of UV-B as evidenced by less damage to DNA. However, it was also found that other environmental factors contributed to the induction of foliar screening compounds.

  5. UV-B radiation and photosynthetic irradiance acclimate eggplant for outdoor exposure

    NASA Technical Reports Server (NTRS)

    Latimer, J. G.; Mitchell, C. A.; Mitchell, G. A.

    1987-01-01

    Treatment of greenhouse-grown eggplant (Solanum melongena L. var. esculentum Nees. 'Burpee's Black Beauty') seedlings with supplemental photosynthetically active radiation from cool-white fluorescent lamps increased growth of plants subsequently transferred outdoors relative to growth of plants that received no supplemental radiation or were shaded to 45% of solar irradiation in the greenhouse before transfer outdoors. Eggplant seedlings transferred outdoors were placed under plastic tarps either to provide relative protection from solar ultraviolet-B (UV-B) radiation (280-315 nm) using Mylar film or to allow exposure to UV-B using cellulose acetate. Protection of seedlings from UV-B radiation resulted in greater leaf expansion than for UV-B-exposed seedlings, but no change in leaf or shoot dry weight occurred after 9 days of treatment. Specific leaf weight increased in response to UV-B exposure outdoors. Exposure of eggplant to UV-B radiation from fluorescent sunlamps in the greenhouse also decreased leaf expansion and leaf and shoot dry weight gain after 5 days of treatment. However, there were no differences in leaf or shoot dry weight relative to control plants after 12 days of UV-B treatment, indicating that UV-B treated plants had acclimated to the treatment and actually had caught up with non-UV-B-irradiated plants in terms of growth.

  6. Response of marine microalgae, heterotrophic bacteria and their relationship to enhanced UV-B radiation

    NASA Astrophysics Data System (ADS)

    Zhou, Wenli; Tang, Xuexi; Xiao, Hui; Wang, You; Wang, Renjun

    2009-03-01

    Ozone depletion in the stratosphere has enhanced solar UV-B radiation reaching the Earth surface and has brought about significant effects to marine ecosystems. The effects of enhanced UV-B radiation on marine microalgae, heterotrophic bacteria and the interaction between them are discussed. The effects on marine microalgae have been proved to occur at molecular, cellular and population levels. Enhanced UV-B radiation increases microalgal flavonoid content but decreases their chlorophyll content and photosynthesis rate; this radiation induces genetic change and results in DNA damage and change of protein content. There have been fewer studies on the effects of UV-B radiation on marine heterotrophic bacteria. Establishment of a microalgal ecological dynamic model at population and community levels under UV-B radiation has gradually become a hotspot. The effects of enhanced UV-B radiation on microalgae communities, heterotrophic bacterial populations and interaction between them will become a focus in the near future. This paper will make an overview on the studies concerning the effects of enhanced UV-B radiation on marine microalgae and heterotrophic bacteria and the interaction between them.

  7. Internal pigment cells respond to external UV radiation in frogs.

    PubMed

    Franco-Belussi, Lilian; Nilsson Sköld, Helen; de Oliveira, Classius

    2016-05-01

    Fish and amphibians have pigment cells that generate colorful skins important for signaling, camouflage, thermoregulation and protection against ultraviolet radiation (UVR). However, many animals also have pigment cells inside their bodies, on their internal organs and membranes. In contrast to external pigmentation, internal pigmentation is remarkably little studied and its function is not well known. Here, we tested genotoxic effects of UVR and its effects on internal pigmentation in a neotropical frog, Physalaemus nattereri We found increases in body darkness and internal melanin pigmentation in testes and heart surfaces and in the mesenterium and lumbar region after just a few hours of UVR exposure. The melanin dispersion in melanomacrophages in the liver and melanocytes in testes increased after UV exposure. In addition, the amount of melanin inside melanomacrophages cells also increased. Although mast cells were quickly activated by UVR, only longer UVR exposure resulted in genotoxic effects inside frogs, by increasing the frequency of micronuclei in red blood cells. This is the first study to describe systemic responses of external UVR on internal melanin pigmentation, melanomacrophages and melanocytes in frogs and thus provides a functional explanation to the presence of internal pigmentation. PMID:26944494

  8. Effect of radiation heat transfer on thermal diffusivity measurements

    NASA Astrophysics Data System (ADS)

    Araki, N.

    1990-03-01

    Experimental data on thermal conductivity and thermal diffusivity of a semitransparent material generally include an error due to the radiation heat transfer. This error varies in accordance with the experimental conditions such as the temperature level of the sample and the measuring method. In this paper, research on the influence of radiation heat transfer on thermal diffusivity are reviewed, and as an example, the method to correct the radiation component in the apparent thermal diffusivity measured by the stepwise heating technique is presented. The transient heat transfer by simultaneous thermal conduction and radiation in a semitransparent material is analyzed when the front surface is subjected to stepwise heating. The apparent thermal diffusivity, which includes the radiation component, is calculated for various parameters.

  9. Effects of UV radiation on aquatic ecosystems and interactions with other environmental factors.

    PubMed

    Häder, Donat-P; Williamson, Craig E; Wängberg, Sten-Åke; Rautio, Milla; Rose, Kevin C; Gao, Kunshan; Helbling, E Walter; Sinha, Rajeshwar P; Worrest, Robert

    2015-01-01

    Interactions between climate change and UV radiation are having strong effects on aquatic ecosystems due to feedback between temperature, UV radiation, and greenhouse gas concentration. Higher air temperatures and incoming solar radiation are increasing the surface water temperatures of lakes and oceans, with many large lakes warming at twice the rate of regional air temperatures. Warmer oceans are changing habitats and the species composition of many marine ecosystems. For some, such as corals, the temperatures may become too high. Temperature differences between surface and deep waters are becoming greater. This increase in thermal stratification makes the surface layers shallower and leads to stronger barriers to upward mixing of nutrients necessary for photosynthesis. This also results in exposure to higher levels of UV radiation of surface-dwelling organisms. In polar and alpine regions decreases in the duration and amount of snow and ice cover on lakes and oceans are also increasing exposure to UV radiation. In contrast, in lakes and coastal oceans the concentration and colour of UV-absorbing dissolved organic matter (DOM) from terrestrial ecosystems is increasing with greater runoff from higher precipitation and more frequent extreme storms. DOM thus creates a refuge from UV radiation that can enable UV-sensitive species to become established. At the same time, decreased UV radiation in such surface waters reduces the capacity of solar UV radiation to inactivate viruses and other pathogens and parasites, and increases the difficulty and price of purifying drinking water for municipal supplies. Solar UV radiation breaks down the DOM, making it more available for microbial processing, resulting in the release of greenhouse gases into the atmosphere. In addition to screening solar irradiance, DOM, when sunlit in surface water, can lead to the formation of reactive oxygen species (ROS). Increases in carbon dioxide are in turn acidifying the oceans and inhibiting

  10. Beneficial effects of UV radiation other than via vitamin D production

    PubMed Central

    Juzeniene, Asta; Moan, Johan

    2012-01-01

    Most of the positive effects of solar radiation are mediated via ultraviolet-B (UVB) induced production of vitamin D in skin. However, several other pathways may exist for the action of ultraviolet (UV) radiation on humans as focused on in this review. One is induction of cosmetic tanning (immediate pigment darkening, persistent pigment darkening and delayed tanning). UVB-induced, delayed tanning (increases melanin in skin after several days), acts as a sunscreen. Several human skin diseases, like psoriasis, vitiligo, atopic dermatitis and localized scleroderma, can be treated with solar radiation (heliotherapy) or artificial UV radiation (phototherapy). UV exposure can suppress the clinical symptoms of multiple sclerosis independently of vitamin D synthesis. Furthermore, UV generates nitric oxide (NO), which may reduce blood pressure and generally improve cardiovascular health. UVA-induced NO may also have antimicrobial effects and furthermore, act as a neurotransmitter. Finally, UV exposure may improve mood through the release of endorphins. PMID:22928066

  11. Impact of increasing Ultraviolet-B (UV-B) radiation on photosynthetic processes.

    PubMed

    Kataria, Sunita; Jajoo, Anjana; Guruprasad, Kadur N

    2014-08-01

    Increased UV-B radiation on the earth's surface due to depletion of stratospheric ozone layer is one of the changes of current climate-change pattern. The deleterious effects of UV-B radiation on photosynthesis and photosynthetic productivity of plants are reviewed. Perusal of relevant literature reveals that UV-B radiation inflicts damage to the photosynthetic apparatus of green plants at multiple sites. The sites of damage include oxygen evolving complex, D1/D2 reaction center proteins and other components on the donor and acceptor sides of PS II. The radiation inactivates light harvesting complex II and alters gene expression for synthesis of PS II reaction center proteins. Mn cluster of water oxidation complex is the most important primary target of UV-B stress whereas D1 and D2 proteins, quinone molecules and cytochrome b are the subsequent targets of UV-B. In addition, photosynthetic carbon reduction is also sensitive to UV-B radiation which has a direct effect on the activity and content of Rubisco. Some indirect effects of UV-B radiation include changes in photosynthetic pigments, stomatal conductance and leaf and canopy morphology. The failure of protective mechanisms makes PS II further vulnerable to the UV-B radiation. Reactive oxygen species are involved in UV-B induced responses in plants, both as signaling and damaging agents. Exclusion of ambient UV components under field conditions results in the enhancement of the rate of photosynthesis, PS II efficiency and subsequently increases the biomass accumulation and crop yield. It is concluded that predicted future increase in UV-B irradiation will have significant impact on the photosynthetic efficiency and the productivity of higher plants. PMID:24725638

  12. Epidermal UV-A absorbance and whole-leaf flavonoid composition in pea respond more to solar blue light than to solar UV radiation.

    PubMed

    Siipola, Sari M; Kotilainen, Titta; Sipari, Nina; Morales, Luis O; Lindfors, Anders V; Robson, T Matthew; Aphalo, Pedro J

    2015-05-01

    Plants synthesize phenolic compounds in response to certain environmental signals or stresses. One large group of phenolics, flavonoids, is considered particularly responsive to ultraviolet (UV) radiation. However, here we demonstrate that solar blue light stimulates flavonoid biosynthesis in the absence of UV-A and UV-B radiation. We grew pea plants (Pisum sativum cv. Meteor) outdoors, in Finland during the summer, under five types of filters differing in their spectral transmittance. These filters were used to (1) attenuate UV-B; (2) attenuate UV-B and UV-A < 370 nm; (3) attenuate UV-B and UV-A; (4) attenuate UV-B, UV-A and blue light; and (5) as a control not attenuating these wavebands. Attenuation of blue light significantly reduced the flavonoid content in leaf adaxial epidermis and reduced the whole-leaf concentrations of quercetin derivatives relative to kaempferol derivatives. In contrast, UV-B responses were not significant. These results show that pea plants regulate epidermal UV-A absorbance and accumulation of individual flavonoids by perceiving complex radiation signals that extend into the visible region of the solar spectrum. Furthermore, solar blue light instead of solar UV-B radiation can be the main regulator of phenolic compound accumulation in plants that germinate and develop outdoors. PMID:25040832

  13. Human projected area factors for detailed direct and diffuse solar radiation analysis.

    PubMed

    Kubaha, K; Fiala, D; Toftum, J; Taki, A H

    2004-11-01

    Projected area factors for individual segments of the standing and sedentary human body were modelled for both direct and diffuse solar radiation using detailed 3D geometry and radiation models. The local projected area factors with respect to direct short-wave radiation are a function of the solar azimuth angle (alpha) between 0 degrees < alpha<360 degrees and the solar altitude (beta) angles between -90 degrees < beta<+90 degrees . In case of diffuse solar radiation from the isotropic sky the local human projected area factors were modelled as a function of the ground albedo (rho) ranging between 0< rho<1. The model was validated against available experimental data and showed good general agreement with projected area factors measured for both the human body as a whole and for local quantities. Scientists can use the equations to predict the inhomogeneous irradiation and absorption of direct and diffuse solar radiation and UV-radiation at surfaces of the human body. In conjunction with detailed multi-node models of human thermoregulation the equations can be used to predict the physiological implications of solar radiation and outdoor weather conditions on humans. PMID:15278684

  14. Oceanic protection of prebiotic organic compounds from UV radiation

    NASA Technical Reports Server (NTRS)

    Cleaves, H. J.; Miller, S. L.; Bada, J. L. (Principal Investigator)

    1998-01-01

    It is frequently stated that UV light would cause massive destruction of prebiotic organic compounds because of the absence of an ozone layer. The elevated UV flux of the early sun compounds this problem. This applies to organic compounds of both terrestrial and extraterrestrial origin. Attempts to deal with this problem generally involve atmospheric absorbers. We show here that prebiotic organic polymers as well as several inorganic compounds are sufficient to protect oceanic organic molecules from UV degradation. This aqueous protection is in addition to any atmospheric UV absorbers and should be a ubiquitous planetary phenomenon serving to increase the size of planetary habitable zones.

  15. UV radiation, vitamin D, and cancer: how to measure the vitamin D synthetic capacity of UV sources?

    NASA Astrophysics Data System (ADS)

    Terenetskaya, Irina; Orlova, Tatiana

    2005-09-01

    UV irradiation is widely used in phototherapy. Regardless of the fact that UV overexposure is liable to cause adverse health effect, in appropriate doses UV radiation initiates synthesis of vitamin D in skin that is absolutely essential for human health. As it proved, most people in northern industrial countries have a level of vitamin D in their bodies that is insufficient for optimum health, especially in winter. These low levels of vitamin D are now known to be associated with a wide spectrum of serious disease much of which leads on to premature death. The diseases associated with D deficiency involve more than a dozen types of cancer including colon, breast and prostate, as well as the classic bone diseases: rickets, osteoporosis and osteomalacia. Irradiation with artificial UV sources can prevent the vitamin D deficiency. However, in view of different irradiation spectra of UV lamps, their ability to initiate vitamin D synthesis is different. The reliable method based on an in vitro model of vitamin D synthesis has been developed for direct measurement in situ of the vitamin D synthetic capacity of artificial UV sources during a phototherapeutic procedure

  16. Re-interpreting plant morphological responses to UV-B radiation.

    PubMed

    Robson, T Matthew; Klem, Karel; Urban, Otmar; Jansen, Marcel A K

    2015-05-01

    There is a need to reappraise the effects of UV-B radiation on plant morphology in light of improved mechanistic understanding of UV-B effects, particularly elucidation of the UV RESISTANCE LOCUS 8 (UVR8) photoreceptor. We review responses at cell and organismal levels, and explore their underlying regulatory mechanisms, function in UV protection and consequences for plant fitness. UV-induced morphological changes include thicker leaves, shorter petioles, shorter stems, increased axillary branching and altered root:shoot ratios. At the cellular level, UV-B morphogenesis comprises changes in cell division, elongation and/or differentiation. However, notwithstanding substantial new knowledge of molecular, cellular and organismal UV-B responses, there remains a clear gap in our understanding of the interactions between these organizational levels, and how they control plant architecture. Furthermore, despite a broad consensus that UV-B induces relatively compact architecture, we note substantial diversity in reported phenotypes. This may relate to UV-induced morphological changes being underpinned by different mechanisms at high and low UV-B doses. It remains unproven whether UV-induced morphological changes have a protective function involving shading and decreased leaf penetration of UV-B, counterbalancing trade-offs such as decreased photosynthetic light capture and plant-competitive abilities. Future research will need to disentangle seemingly contradictory interactions occurring at the threshold UV dose where regulation and stress-induced morphogenesis overlap. PMID:24890713

  17. Spectral Observations of the Diffuse FUV Background with DUVE (the Diffuse UV Experiment)

    NASA Astrophysics Data System (ADS)

    Korpela, E. J.; Bowyer, S.

    We present results from a search for FUV emission from the diffuse ISM conducted with an orbital FUV spectrometer, DUVE, which was launched in July, 1992. The DUVE spectrometer, which covers the band from 950 Angstroms to 1080 Angstroms with 3.2 Angstroms resolution, observed a region of low neutral hydrogen column density near the south galactic pole for a total effective integration time of 1583 seconds. The only emission line detected was a geocoronal hydrogen line at 1025 Angstroms. We were able to place upper limits to several emission features that provide constraints to interstellar plasma parameters. We were also able to place continuum limits in this band. We use these upper limits to place constraints upon the emission measure vs. temperature distribution of this gas using an isothermal Landini and Fossi model.

  18. Oxygen radical production in bluegill sunfish liver microsomes exposed to anthracene and UV radiation

    SciTech Connect

    Choi, J.; Oris, J.

    1995-12-31

    Many polycyclic aromatic hydrocarbons (PAHs) are acutely toxic to fish in the presence of ultraviolet radiation. Oxygen radicals are very reactive and are responsible for many cellular injuries including membrane peroxidation and DNA fragmentation. In this research increased oxygen radical production was hypothesized for the mechanism of UV-PAH acute toxicity. In order to test this hypothesis Bluegill sunfish (Lepomis machrochirus) liver microsomes were exposed to anthracene and UV radiation in four different combinations: (No UV + No Ant), (No UV + Ant), (UV + No Ant), (UV + Ant). The production of superoxide anion was quantified by measuring the spectrophotometric absorbance of acetylated cytochrome c, which is reduced by superoxide anion. 1 ml of reaction solution contained 1 mg of microsomes and, for Ant treatments, 7.7 {micro}g of anthracene. After 3 hours preincubation, acetylated cytochrome c solution was added. The UV treatment groups were exposed to UV-A for 20 minutes at 37 C. The highest mean concentration of reduced acetylated cytochrome c was found in the UV + Ant treatment group and it was significantly different from all other treatment groups. No significant differences were observed among the other three treatment groups. This result coincides with previous studies revealing that anthracene is acutely toxic to fish only under UV radiation, and it implies that the photoinduced toxicity of anthracene, as well as other PAHs, is manifested by the action of oxygen radicals.

  19. Solar UV radiation variations and their stratospheric and climatic effects

    NASA Technical Reports Server (NTRS)

    Donnelly, R. F.; Heath, D. F.

    1985-01-01

    Nimbus-7 SBUV measurements of the short-term solar UV variations caused by solar rotation and active-region evolution have determined the amplitude and wavelength dependence for the active-region component of solar UV variations. Intermediate-term variations lasting several months are associated with rounds of major new active regions. The UV flux stays near the peak value during the current solar cycle variation for more than two years and peaks about two years later than the sunspot number. Nimbus-7 measurements have observed the concurrent stratospheric ozone variations caused by solar UV variations. There is now no doubt that solar UV variations are an important cause of short- and long-term stratospheric variations, but the strength of the coupling to the troposphere and to climate has not yet been proven.

  20. Human skin pigmentation as an adaptation to UV radiation

    PubMed Central

    Jablonski, Nina G.; Chaplin, George

    2010-01-01

    Human skin pigmentation is the product of two clines produced by natural selection to adjust levels of constitutive pigmentation to levels of UV radiation (UVR). One cline was generated by high UVR near the equator and led to the evolution of dark, photoprotective, eumelanin-rich pigmentation. The other was produced by the requirement for UVB photons to sustain cutaneous photosynthesis of vitamin D3 in low-UVB environments, and resulted in the evolution of depigmented skin. As hominins dispersed outside of the tropics, they experienced different intensities and seasonal mixtures of UVA and UVB. Extreme UVA throughout the year and two equinoctial peaks of UVB prevail within the tropics. Under these conditions, the primary selective pressure was to protect folate by maintaining dark pigmentation. Photolysis of folate and its main serum form of 5-methylhydrofolate is caused by UVR and by reactive oxygen species generated by UVA. Competition for folate between the needs for cell division, DNA repair, and melanogenesis is severe under stressful, high-UVR conditions and is exacerbated by dietary insufficiency. Outside of tropical latitudes, UVB levels are generally low and peak only once during the year. The populations exhibiting maximally depigmented skin are those inhabiting environments with the lowest annual and summer peak levels of UVB. Development of facultative pigmentation (tanning) was important to populations settling between roughly 23° and 46° , where levels of UVB varied strongly according to season. Depigmented and tannable skin evolved numerous times in hominin evolution via independent genetic pathways under positive selection. PMID:20445093

  1. Continuous dosimetry of the biologically harmful UV-radiation in Antarctica with the biofilm technique.

    PubMed

    Quintern, L E; Puskeppeleit, M; Rainer, P; Weber, S; el Naggar, S; Eschweiler, U; Horneck, G

    1994-01-01

    For the first time, a continuous biological dosimetry experiment for cytotoxic solar UV-radiation has been performed in Antarctica. The biologically harmful UV-radiation on the ground was measured at the German Antarctic Georg von Neumayer Station (70 degrees 37' S, 80 degrees 22' W) from December 1990 to March 1992 using the biofilm technique. The UV-sensitive targets were dried spores of Bacillus subtilis which were immobilized on the film surface. The UV-induced inhibition of biological activity, determined photometrically from the protein synthesized after incubation and staining, was taken as a measure for the absorbed UV-dose. Films were exposed in horizontal position for time intervals ranging from 4 days during summer up to 51 and 41 days before and after the polar night respectively. The use of different cut-off filters allowed the calculation of the biologically effective UVA, UVB and the complete UV-radiation (UVA + B). The data were compared with the global radiation and the ozone column thickness indicating an increase of biologically harmful UVB radiation during austral spring at reduced ozone concentrations yielding a radiation amplification factor (RAF) of 1.4, whereas for the total UV(A + B) range the RAF amounted to 0.3. PMID:8151457

  2. Radiation Diffusion:. AN Overview of Physical and Numerical Concepts

    NASA Astrophysics Data System (ADS)

    Graziani, Frank

    2005-12-01

    An overview of the physical and mathematical foundations of radiation transport is given. Emphasis is placed on how the diffusion approximation and its transport corrections arise. An overview of the numerical handling of radiation diffusion coupled to matter is also given. Discussions center on partial temperature and grey methods with comments concerning fully implicit methods. In addition finite difference, finite element and Pert representations of the div-grad operator is also discussed

  3. Discrete diffusion Monte Carlo for frequency-dependent radiative transfer

    SciTech Connect

    Densmore, Jeffrey D; Kelly, Thompson G; Urbatish, Todd J

    2010-11-17

    Discrete Diffusion Monte Carlo (DDMC) is a technique for increasing the efficiency of Implicit Monte Carlo radiative-transfer simulations. In this paper, we develop an extension of DDMC for frequency-dependent radiative transfer. We base our new DDMC method on a frequency-integrated diffusion equation for frequencies below a specified threshold. Above this threshold we employ standard Monte Carlo. With a frequency-dependent test problem, we confirm the increased efficiency of our new DDMC technique.

  4. Growth of a mat-forming photograph in the presence of UV radiation

    NASA Technical Reports Server (NTRS)

    Pierson, Beverly K.; Ruff, A. L.

    1989-01-01

    Knowledge of the survival and growth of microorganisms in the presence of ultraviolet radiation is important for understanding the potential for life to exist in environments exposed to high fluxes of UV radiation. The growth of a mat-forming phototrophic prokaryote, Chloroflexus aurantiacus, was examined in the presence of continuous high UV irradiation under otherwise optimal growth conditions. Evidence was sought for an intrinsic ability to grow in the presence of UV radiation in a carefully chosen organism known to be unusually resistant to UV radiation, of ancient lineage among the phototrophs, to resemble ancient microfossils from the Precambrian, and to be a mat-former. It was assumed that even a high intrinsic UV resistance would be inadequate for survival and growth in the presence of very high UV fluxes, and iron (Fe3+) was selected as a common, abundant UV-absorbing substance that might protest microorganisms growing in or under iron-bearing sediments. The effectiveness of Fe(3+) was tested as a UV protective agent at low concentrations in thin layers. It was concluded that intrinsic UV resistance in some organisms may account for growth, not just survival, of these organisms when exposed to high UV fluxes under otherwise optimal growth conditions in an anoxic environment. It was also concluded that Fe(3+) bearing sediments of 1 mm or less in thickness may provide an adequate shield against high UV fluxes permitting the growth of microorganisms just below their surface. As long as growth conditions were met, then the evolution and development of microorganisms would not be hampered by high UV fluxes impinging upon the surface of iron-bearing sediments.

  5. MicroRNA-22 promotes cell survival upon UV radiation by repressing PTEN

    SciTech Connect

    Tan, Guangyun; Shi, Yuling; Wu, Zhao-Hui

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer miR-22 is induced in cells treated with UV radiation. Black-Right-Pointing-Pointer ATM is required for miR-22 induction in response to UV. Black-Right-Pointing-Pointer miR-22 targets 3 Prime -UTR of PTEN to repress its expression in UV-treated cells. Black-Right-Pointing-Pointer Upregulated miR-22 inhibits apoptosis in cells exposed to UV. -- Abstract: DNA damage response upon UV radiation involves a complex network of cellular events required for maintaining the homeostasis and restoring genomic stability of the cells. As a new class of players involved in DNA damage response, the regulation and function of microRNAs in response to UV remain poorly understood. Here we show that UV radiation induces a significant increase of miR-22 expression, which appears to be dependent on the activation of DNA damage responding kinase ATM (ataxia telangiectasia mutated). Increased miR-22 expression may result from enhanced miR-22 maturation in cells exposed to UV. We further found that tumor suppressor gene phosphatase and tensin homolog (PTEN) expression was inversely correlated with miR-22 induction and UV-induced PTEN repression was attenuated by overexpression of a miR-22 inhibitor. Moreover, increased miR-22 expression significantly inhibited the activation of caspase signaling cascade, leading to enhanced cell survival upon UV radiation. Collectively, these results indicate that miR-22 is an important player in the cellular stress response upon UV radiation, which may promote cell survival via the repression of PTEN expression.

  6. Degassing a vacuum system with in-situ UV radiation

    SciTech Connect

    Koebley, Sean R.; Outlaw, Ronald A.; Dellwo, Randy R.

    2012-11-15

    Photon-stimulated desorption (PSD) from a high-powered ultraviolet source was investigated as a technique to degas a vacuum system. A stainless steel vacuum system was pumped down from atmosphere with different time doses of 185 nm light, and the resulting outgassing rates were compared to that of a control pumpdown without UV assistance. PSD was found to provide a factor of 2 advantage in pumpdown pressure after only 30 min of UV exposure, with no additional advantage observed for longer irradiation times. Specifically, an outgassing rate of 3 Multiplication-Sign 10{sup -10} Torr L s{sup -1} cm{sup -2} was reached 3 h sooner in pumpdowns with UV assistance compared to those without UV, while a rate of 1.2 Multiplication-Sign 10{sup -10} Torr L s{sup -1} cm{sup -2} was reached 16 h sooner in UV runs. The authors calculated that about 22 monolayers of water were desorbed after 30 min of UV exposure. The results indicate that PSD by a 40 W 185 nm UV source can serve as a nonthermal technique to significantly speed the pumpdown of a vacuum system from atmosphere after only 30 min.

  7. Correlation of total, diffuse, and direct solar radiation

    NASA Technical Reports Server (NTRS)

    Buyco, E. H.; Namkoong, D.

    1977-01-01

    Present requirements for realistic solar energy system evaluations necessitate a comprehensive body of solar-radition data. The data should include both diffuse and direct solar radiation as well as their total on an hourly (or shorter) basis. In general, however, only the total solar radiation values were recorded. This report presents a correlation that relates the diffuse component of an hourly total solar radiation value to the total radiation ratio of the maximum value attainable. The data used were taken at the Blue Hill Observatory in Milton, Massachusetts, for the period 1952. The relation - in the form of the data plots - can be used in situations in which only the hourly total radiation data are available but the diffuse component is desired.

  8. INTERACTIVE EFFECTS OF SOLAR UV RADIATION AND CLIMATE CHANGE ON BIOGEOCHEMICAL CYCLING

    EPA Science Inventory

    This paper assesses research on the interactions of UV radiation (280-400 nm) and global climate change with global biogeochemical cycles at the Earth's surface. The effects of UV-B (280-315 nm), which are dependent on the stratospheric ozone layer, on biogeochemical cycles are o...

  9. INTERACTIONS OF SOLAR UV RADIATION AND DISSOLVED ORGANIC MATTER IN AQUATIC ENVIRONMENTS

    EPA Science Inventory

    Changes in the ozone layer over the past two decades have resulted in increases in solar ultraviolet (UV) radiation that reaches the surface of aquatic environments. Recent studies have demonstrated that these UV increases cause changes in photochemical reactions that affect the...

  10. Environmental controls of UV-B radiation in forested streams of northern Michigan.

    PubMed

    Frost, Paul C; Mack, Alyson; Larson, James H; Bridgham, Scott D; Lamberti, Gary A

    2006-01-01

    We examined UV-B radiation flux and its environmental control within and among streams of northern Michigan. UV-B flux was estimated in streams by plastic dosimetry strips, which allow for the simultaneous and repeated in situ measurement of solar radiation. During the summer of 2004, UV-B flux was measured across depth gradients and along longitudinal transects in seven streams, which were chosen to encompass a range of dissolved organic carbon (DOC) concentrations and canopy cover. Attenuation coefficients of UV-B (K(d) (UV-B)) were estimated using plastic dosimeters placed along a depth gradient. K(d UV-B) were positively correlated with DOC concentration and similar to values obtained with laboratory and in situ spectrometry. Along 100 m longitudinal transects, UV-B flux varied along all streams regardless of their canopy cover and DOC concentration. Within-stream fluxes of UV-B were correlated to canopy cover in the only two streams that both had relatively low DOC concentration and variable canopy cover. Large differences were found among streams in the average UV-B flux (corrected for incident solar flux) reaching the dosimeters at 5 cm depth. These among-stream differences were largely accounted for by the stream width, canopy cover, and DOC concentration. Our results illustrate an inherent variability in UV-B flux within and among streams of northern Michigan that is strongly tied to the interactions of DOC concentration, stream size and riparian vegetation. PMID:16454579

  11. Theoretical models of interstellar shocks. I - Radiative transfer and UV precursors

    NASA Technical Reports Server (NTRS)

    Shull, J. M.; Mckee, C. F.

    1979-01-01

    Theoretical models of interstellar radiative shocks are constructed, with special attention to the transfer of ionizing radiation. These models are 'self-consistent' in the sense that the emergent ionizing radiation (the UV precursor) is coupled with the ionization state of H, He, and the metals in the preshock gas. For shock velocities of at least 110 km/s the shocks generate sufficient UV radiation for complete preionization of H and He, the latter to He(+). At lower velocities the preionization can be much smaller, with important consequences for the cooling function, the shock structure, and the emission. For models with shock velocities of 40 to 130 km/s the intensities of the strongest emission lines in the UV, optical, and infrared are tabulated, as well as postshock column densities of metal ions potentially observable by UV absorption spectroscopy. Possible applications to supernova remnants and high-velocity interstellar gas are assessed.

  12. High-power spontaneous UV radiation source and its excitation regimes

    SciTech Connect

    Baksht, E Kh; Lomaev, Mikhail I; Panchenko, Aleksei N; Rybka, D V; Tarasenko, Viktor F; Krishnan, M; Thompson, J

    2005-07-31

    Different excitation regimes of a discharge in a xenon flashlamp are studied. It is shown that in passing from the oscillating discharge current to the unidirectional current pulse, the UV power radiation increases, while the FWHM of the radiation pulses decreases. The maximum UV power density of the discharge restricted by the flashlamp tube walls was {approx}700 and {approx}380 kW cm{sup -2} on the internal and external surfaces of the flashlamp tube, respectively. (active media)

  13. Analysis of differentially expressed genes under UV-B radiation in the desert plant Reaumuria soongorica.

    PubMed

    Liu, Meiling; Li, Xinrong; Liu, Yubing; Shi, Yulan; Ma, Xiaofei

    2015-12-15

    Reaumuria soongorica is one of the typical desert plants that present excellent tolerance to adverse environments. However, its molecular response to UV-B radiation remains poorly understood. To test the response and tolerance mechanisms of R. soongorica to the increasing UV-B radiation, the differentially expressed genes (DEGs) were investigated between the control and UV-B radiation groups. A total of 2150 DEGs were detected between the two groups, of which 561 were up-regulated and 1589 were down-regulated. For functional analysis, DEGs were divided into three groups: (i) Chloroplast-localized proteins, including photosynthesis-associated proteins, ribulose-phosphate-3-epimerase, and ATP-dependent Clp protease. Their transcripts were inhibited, implying that the normal function of chloroplast was affected by UV-B radiation. (ii) Proteins involved in signaling transduction, such as phototropins and GTP-binding proteins. The transcriptional alternation of phototropins may reduce the penetration of UV-B radiation by regulating phototropism, stomatal opening, and chloroplast relocation. The down regulation of GTP-binding proteins may inhibit replication of potentially damaged DNA through preventing cell division; and (iii) proteins for lipid transfer and flavonoids biosynthesis. The up-regulation of these genes suggested that lipid transfer and flavonoids may have a protective function in response to UV-B radiation. Thus, UV-B radiation may lead to the disruption of chloroplasts function. The induction of genes for signal transduction and protective proteins may be a strategy for responding to UV-B radiation in R. soongorica. PMID:26277248

  14. Diffuser for intravessels radiation based on plastic fiber

    NASA Astrophysics Data System (ADS)

    Pich, Justyna; Grobelny, Andrzej; Beres-Pawlik, Elzbieta

    2006-03-01

    Laser radiation is used in such contemporary medicine as: sport medicine, gynecology etc. Because of many radiations inside the system, there is a need of an element, which allows to supply the place of illness with energy. The dimensions of this element are often small and the one that meets these conditions is diffuser.

  15. Reproductive, morphological, and phytochemical responses of Arabidopsis thaliana ecotypes to enhanced UV-B radiation

    SciTech Connect

    Trumbull, V.L.; McCloud, E.S.; Paige, K.N. )

    1994-06-01

    Two ecotypes of Arabidopsis thaliana, collected from Libya and Norway, were grown in the greenhouse under. UV-B doses of 0 and 10.5 kJ m[sup [minus]2] UV-B[sub BE]. The high UV-B dose simulated midsummer ambient conditions over Libya and a 40% reduction in stratospheric ozone over Norway. The Libyan ectotype, which originated from latitudes where solar UV-B is high, showed no UV-B induced damage to plant growth. However the Norwegian ecotype, which originated from latitudes where solar UV-B is low, showed a significant reduction in plant height, inflorescence weight, and rosette weight in response to enhanced UV-B. Although fruit and seed number for both ecotypes were unaffected by enhanced UV-B radiation the germination success of the seeds harvested from the irradiated Norwegian plants were significantly reduced. The two ecotypes also differed with respect to their accumulation of kaempferol, a putative UV-B protective filter. The Libyan ecotype increased kaempferol concentration by 38% over the 0 kJ treatment whereas the Norwegian ecotype increased by only 15%. These data suggest that, for these ecotypes, variation in UV-B sensitivity may be explained by the differential induction of UV-absorbing leaf pigments.

  16. Effects of solar UV radiation on aquatic ecosystems and interactions with climate change.

    PubMed

    Häder, D-P; Kumar, H D; Smith, R C; Worrest, R C

    2007-03-01

    Recent results continue to show the general consensus that ozone-related increases in UV-B radiation can negatively influence many aquatic species and aquatic ecosystems (e.g., lakes, rivers, marshes, oceans). Solar UV radiation penetrates to ecological significant depths in aquatic systems and can affect both marine and freshwater systems from major biomass producers (phytoplankton) to consumers (e.g., zooplankton, fish, etc.) higher in the food web. Many factors influence the depth of penetration of radiation into natural waters including dissolved organic compounds whose concentration and chemical composition are likely to be influenced by future climate and UV radiation variability. There is also considerable evidence that aquatic species utilize many mechanisms for photoprotection against excessive radiation. Often, these protective mechanisms pose conflicting selection pressures on species making UV radiation an additional stressor on the organism. It is at the ecosystem level where assessments of anthropogenic climate change and UV-related effects are interrelated and where much recent research has been directed. Several studies suggest that the influence of UV-B at the ecosystem level may be more pronounced on community and trophic level structure, and hence on subsequent biogeochemical cycles, than on biomass levels per se. PMID:17344962

  17. Near-UV radiation acts as a beneficial factor for physiological responses in cucumber plants.

    PubMed

    Mitani-Sano, Makiko; Tezuka, Takafumi

    2013-11-01

    Effects of near-UV radiation on the growth and physiological activity of cucumber plants were investigated morphologically, physiologically and biochemically using 3-week-old seedlings grown under polyvinyl chloride films featuring transmission either above 290 nm or above 400 nm in growth chambers. The hypocotyl length and leaf area of cucumber seedlings were reduced but the thickness of leaves was enhanced by near-UV radiation, due to increased upper/lower epidermis thickness, palisade parenchyma thickness and volume of palisade parenchyma cells. Photosynthetic and respiratory activities were also promoted by near-UV radiation, associated with general enhancement of physiological/biochemical responses. Particularly, metabolic activities in the photosynthetic system of chloroplasts and the respiratory system of mitochondria were analyzed under the conditions of visible light with and without near-UV radiation. For example, the activities of NAD(P)-dependent enzymes such as glyceraldehyde-3-phosphate dehydrogenase (G3PDH) in chloroplasts and isocitrate dehydrogenase (ICDH) in mitochondria were elevated, along with levels of pyridine nucleotides (nicotinamide coenzymes) [NAD(H) and NADP(H)] and activity of NAD kinase (NADP forming enzyme). Taken together, these data suggest that promotion of cucumber plant growth by near-UV radiation involves activation of carbon and nitrogen metabolism in plants. The findings of this research showed that near-UV radiation reaching the Earth's surface is a beneficial factor for plant growth. PMID:24013482

  18. Biological space experiments for the simulation of Martian conditions: UV radiation and Martian soil analogues

    NASA Astrophysics Data System (ADS)

    Rettberg, P.; Rabbow, E.; Panitz, C.; Horneck, G.

    2004-01-01

    The survivability of resistant terrestrial microbes, bacterial spores of Bacillus subtilis, was investigated in the BIOPAN facility of the European Space Agency onboard of Russian Earth-orbiting FOTON satellites (BIOPAN I -III missions). The spores were exposed to different subsets of the extreme environmental parameters in space (vacuum, extraterrestrial solar UV, shielding by protecting materials like artificial meteorites). The results of the three space experiments confirmed the deleterious effects of extraterrestrial solar UV radiation which, in contrast to the UV radiation reaching the surface of the Earth, also contains the very energy-rich, short wavelength UVB and UVC radiation. Thin layers of clay, rock or meteorite material were shown to be only successful in UV-shielding, if they are in direct contact with the spores. On Mars the UV radiation climate is similar to that of the early Earth before the development of a protective ozone layer in the atmosphere by the appearance of the first aerobic photosynthetic bacteria. The interference of Martian soil components and the intense and nearly unfiltered Martian solar UV radiation with spores of B. subtilis will be tested with a new BIOPAN experiment, MARSTOX. Different types of Mars soil analogues will be used to determine on one hand their potential toxicity alone or in combination with solar UV (phototoxicity) and on the other hand their UV protection capability. Two sets of samples will be placed under different cut-off filters used to simulate the UV radiation climate of Mars and Earth. After exposure in space the survival of and mutation induction in the spores will be analyzed at the DLR, together with parallel samples from the corresponding ground control experiment performed in the laboratory. This experiment will provide new insights into the principal limits of life and its adaptation to environmental extremes on Earth or other planets which and will also have implications for the potential for the

  19. Biological space experiments for the simulation of Martian conditions: UV radiation and Martian soil analogues.

    PubMed

    Rettberg, P; Rabbow, E; Panitz, C; Horneck, G

    2004-01-01

    The survivability of resistant terrestrial microbes, bacterial spores of Bacillus subtilis, was investigated in the BIOPAN facility of the European Space Agency onboard of Russian Earth-orbiting FOTON satellites (BIOPAN I -III missions). The spores were exposed to different subsets of the extreme environmental parameters in space (vacuum, extraterrestrial solar UV, shielding by protecting materials like artificial meteorites). The results of the three space experiments confirmed the deleterious effects of extraterrestrial solar UV radiation which, in contrast to the UV radiation reaching the surface of the Earth, also contains the very energy-rich, short wavelength UVB and UVC radiation. Thin layers of clay, rock or meteorite material were shown to be only successful in UV-shielding, if they are in direct contact with the spores. On Mars the UV radiation climate is similar to that of the early Earth before the development of a protective ozone layer in the atmosphere by the appearance of the first aerobic photosynthetic bacteria. The interference of Martian soil components and the intense and nearly unfiltered Martian solar UV radiation with spores of B. subtilis will be tested with a new BIOPAN experiment, MARSTOX. Different types of Mars soil analogues will be used to determine on one hand their potential toxicity alone or in combination with solar UV (phototoxicity) and on the other hand their UV protection capability. Two sets of samples will be placed under different cut-off filters used to simulate the UV radiation climate of Mars and Earth. After exposure in space the survival of and mutation induction in the spores will be analyzed at the DLR, together with parallel samples from the corresponding ground control experiment performed in the laboratory. This experiment will provide new insights into the principal limits of life and its adaptation to environmental extremes on Earth or other planets which and will also have implications for the potential for the

  20. Response of radiation belt simulations to different radial diffusion coefficients

    NASA Astrophysics Data System (ADS)

    Drozdov, A.; Shprits, Y.; Subbotin, D.; Kellerman, A. C.

    2013-12-01

    Resonant interactions between Ultra Low Frequency (ULF) waves and relativistic electrons may violate the third adiabatic invariant of motion, which produces radial diffusion in the electron radiation belts. This process plays an important role in the formation and structure of the outer electron radiation belt and is important for electron acceleration and losses in that region. Two parameterizations of the resonant wave-particle interaction of electrons with ULF waves in the magnetosphere by Brautigam and Albert [2000] and Ozeke et al. [2012] are evaluated using the Versatile Electron Radiation Belt (VERB) diffusion code to estimate their relative effect on the radiation belt simulation. The period of investigation includes quiet time and storm time geomagnetic activity and is compared to data based on satellite observations. Our calculations take into account wave-particle interactions represented by radial diffusion transport, local acceleration, losses due to pitch-angle diffusion, and mixed diffusion. We show that the results of the 3D diffusion simulations depend on the assumed parametrization of waves. The differences between the simulations and potential missing physical mechanisms are discussed. References Brautigam, D. H., and J. M. Albert (2000), Radial diffusion analysis of outer radiation belt electrons during the October 9, 1990, magnetic storm, J. Geophys. Res., 105(A1), 291-309, doi:10.1029/1999JA900344 Ozeke, L. G., I. R. Mann, K. R. Murphy, I. J. Rae, D. K. Milling, S. R. Elkington, A. A. Chan, and H. J. Singer (2012), ULF wave derived radiation belt radial diffusion coefficients, J. Geophys. Res., 117, A04222, doi:10.1029/2011JA017463.

  1. The evolutionary response of plants to increased UV-B radiation: Field studies with Arabidopsis thaliana

    SciTech Connect

    Trumbull, V.L.; Paige, K.N.

    1995-09-01

    The response of a species to any environmental change is determined by both phenotypic and evolutionary adjustments. To date, the majority of research concerning the response of terrestrial plants to increased UV-B radiation has focused on phenotypic adjustments. Recently we have initiated field studies aimed at assessing genetic variation for UV-B sensitivity within a natural population of Arabidopsis thaliana. This population consists of at least eight discrete genotypes that have been confirmed by RAPD analysis. We used an incomplete block design to assess the impact of UV-B (ambient and ambient + 6 kJ) and PAR (low and high) on these genotypes. The high UV-B treatment caused a significant reduction in fruit number and plant height while the high PAR treatment caused a significant increase in these variables. In addition, there was a marginally significant (p=0.1) UV-B x PAR x maternal line interaction for fruit number, indicating that genetic variation for UV-B sensitivity within this population depends on the PAR environment. The combination of high UV-B and high PAR caused a change in fruit number (relative to the ambient UV-B/high PAR treatment) ranging from an increase of 24% to a decrease of 47%. This range was much smaller in the low PAR treatment. These results indicate the potential for increased UV-B radiation to act as an agent of natural selection within this population.

  2. Ozone and UV radiation over southern South America: climatology and anomalies.

    PubMed

    Diaz, S; Camilión, C; Deferrari, G; Fuenzalida, H; Armstrong, R; Booth, C; Paladini, A; Cabrera, S; Casiccia, C; Lovengreen, C; Pedroni, J; Rosales, A; Zagarese, H; Vernet, M

    2006-01-01

    Ozone and UV radiation were analyzed at eight stations from tropical to sub-Antarctic regions in South America. Ground UV irradiances were measured by multichannel radiometers as part of the Inter American Institute for Global Change Radiation network. The irradiance channels used for this study were centered at 305 nm (for UV-B measurements) and 340 nm (for UV-A measurements). Results were presented as daily maximum irradiances, as monthly averaged, daily integrated irradiances and as the ratio of 305 nm to 340 nm. These findings are the first to be based on a long time series of semispectral data from the southern region of South America. As expected, the UV-B channel and total column ozone varied with latitude. The pattern of the UV-A channel was more complex because of local atmospheric conditions. Total column ozone levels of < 220 Dobson Units were observed at all sites. Analysis of autocorrelations showed a larger persistence of total column ozone level than irradiance. A decreasing cross-correlation coefficient between 305 and 340 nm and an increasing cross-correlation coefficient between 305 nm and ozone were observed at higher latitudes, indicating that factors such as cloud cover tend to dominate at northern sites and that ozone levels tend to dominate at southern sites. These results highlight the value of long-term monitoring of radiation with multichannel radiometers to determine climatological data and evaluate the combination of factors affecting ground UV radiation. PMID:16613525

  3. Adverse Effects of UV-B Radiation on Plants Growing at Schirmacher Oasis, East Antarctica

    PubMed Central

    Singh, Jaswant; Singh, Rudra P.

    2014-01-01

    This study aimed to assess the impacts of ultraviolet-B (UV-B) radiation over a 28-day period on the levels of pigments of Umbilicaria aprina and Bryum argenteum growing in field. The depletion of stratospheric ozone is most prominent over Antarctica, which receives more UV-B radiation than most other parts of the planet. Although UV-B radiation adversely affects all flora, Antarctic plants are better equipped to survive the damaging effects of UV-B owing to defenses provided by UV-B absorbing compounds and other screening pigments. The UV-B radiations and daily average ozone values were measured by sun photometer and the photosynthetic pigments were analyzed by the standard spectrophotometric methods of exposed and unexposed selected plants. The daily average atmospheric ozone values were recorded from 5 January to 2 February 2008. The maximum daily average for ozone (310.7 Dobson Units (DU)) was recorded on 10 January 2008. On that day, average UV-B spectral irradiances were 0.016, 0.071, and 0.186 W m-2 at wavelengths of 305, 312, and 320 nm, respectively. The minimum daily average ozone value (278.6 DU) was recorded on 31 January 2008. On that day, average UV-B spectral irradiances were 0.018, 0.085, and 0.210 W m-2 at wavelengths of 305, 312, and 320 nm, respectively. Our results concludes that following prolonged UV-B exposure, total chlorophyll levels decreased gradually in both species, whereas levels of UV-B absorbing compounds, phenolics, and carotenoids gradually increased. PMID:24748743

  4. Adverse Effects of UV-B Radiation on Plants Growing at Schirmacher Oasis, East Antarctica.

    PubMed

    Singh, Jaswant; Singh, Rudra P

    2014-01-01

    This study aimed to assess the impacts of ultraviolet-B (UV-B) radiation over a 28-day period on the levels of pigments of Umbilicaria aprina and Bryum argenteum growing in field. The depletion of stratospheric ozone is most prominent over Antarctica, which receives more UV-B radiation than most other parts of the planet. Although UV-B radiation adversely affects all flora, Antarctic plants are better equipped to survive the damaging effects of UV-B owing to defenses provided by UV-B absorbing compounds and other screening pigments. The UV-B radiations and daily average ozone values were measured by sun photometer and the photosynthetic pigments were analyzed by the standard spectrophotometric methods of exposed and unexposed selected plants. The daily average atmospheric ozone values were recorded from 5 January to 2 February 2008. The maximum daily average for ozone (310.7 Dobson Units (DU)) was recorded on 10 January 2008. On that day, average UV-B spectral irradiances were 0.016, 0.071, and 0.186 W m(-2) at wavelengths of 305, 312, and 320 nm, respectively. The minimum daily average ozone value (278.6 DU) was recorded on 31 January 2008. On that day, average UV-B spectral irradiances were 0.018, 0.085, and 0.210 W m(-2) at wavelengths of 305, 312, and 320 nm, respectively. Our results concludes that following prolonged UV-B exposure, total chlorophyll levels decreased gradually in both species, whereas levels of UV-B absorbing compounds, phenolics, and carotenoids gradually increased. PMID:24748743

  5. Antarctic network of lamp-calibrated multichannel radiometers for continuous ozone and uv radiation data

    NASA Astrophysics Data System (ADS)

    Redondas, A.; Torres, C.; Meinander, O.; Lakkala, K.; García, R.; Cuevas, E.; Ochoa, H.; Deferrari, G.; Díaz, S.

    2008-02-01

    Three NILU-UV multichannel radiometers have been installed in 1999 at the Argentinian sites of Ushuaia (54S), Marambio (64S) and Belgrano-II (77S) in order to continuously monitor UV radiation, photosynthetically active radiation and total ozone. The measurements were established by INM, Spain in collaboration with FMI, Finland, DNA-IAA, Argentina and CADIC, Argentina to observe and characterize the spatial and temporal evolution of ozone and ultraviolet radiation in the Antarctic region. Special attention has been given to the quality control and quality assurance of the measurements under harsh climatological conditions. The ozone and UV time series of 2000-2006 were calibrated using a polynomial fit for lamp measurements performed every second week all year round. The gaps in these data are minimal, with almost no data missing, and the data products are available from http://www.polarvortex.org in near real time. The data products include the erythemally-weighted UV, UVB and UVA radiation, photosynthetically active radiation (PAR), total ozone (O3) and a cloud parameter (CLT). For UV data, dose rates as well as daily doses are available; from these the maximum measured UV indices (UVI), during 2000-2006, were 12.0, 9.7 and 8.1 at Ushuaia, Marambio and Belgrano-II, respectively.

  6. DNA repair and resistance to UV-B radiation in western spotted frogs

    USGS Publications Warehouse

    Blaustein, A.R.; Hays, J.B.; Hoffman, P.D.; Chivers, D.P.; Kiesecker, J.M.; Leonard, W.P.; Marco, A.; Olson, D.H.; Reaser, J.K.; Anthony, R.G.

    1999-01-01

    We assessed DNA repair and resistance to solar radiation in eggs of members of the western spotted frog complex (Rana pretiosa and R. luteiventris), species whose populations are suffering severe range reductions and declines. Specifically, we measured the activity of photoreactivating enzyme (photolyase) in oocytes of spotted frogs. In some species, photoreactivation is the most important mechanism for repair of UV-damaged DNA. Using field experiments, we also compared the hatching success of spotted frog embryos at natural oviposition sites at three elevations, where some embryos were subjected to ambient levels of UV-B radiation and others were shielded from UV-B radiation. Compared with other amphibians, photolyase activities in spotted frogs were relatively high. At all sites, hatching success was unaffected by UV-B. Our data support the interpretation that amphibian embryos with relatively high levels of photolyase are more resistant to UV-B radiation than those with lower levels of photolyase. At the embryonic stage, UV-B radiation does not presently seem to be contributing to the population declines of spotted frogs.

  7. Modeling Suomi-NPP VIIRS Solar Diffuser Degradation due to Space Radiation

    NASA Astrophysics Data System (ADS)

    Shao, X.; Cao, C.

    2014-12-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP uses a solar diffuser (SD) as on-board radiometric calibrator for the reflective solar band (RSB) calibration. Solar diffuser is made of Spectralon (one type of fluoropolymer) and was chosen because of its controlled reflectance in the VIS-NIR-SWIR region and its near-Lambertian reflectance profile. Spectralon is known to degrade in reflectance at the blue end of the spectrum due to exposure to space radiations such as solar UV radiation and energetic protons. These space radiations can modify the Spectralon surface through breaking C-C and C-F bonds and scissioning or cross linking the polymer, which causes the surface roughness and degrades its reflectance. VIIRS uses a SDSM (Solar Diffuser Stability Monitor) to monitor the change in the Solar Diffuser reflectance in the 0.4 - 0.94 um wavelength range and provide a correction to the calibration constants. The H factor derived from SDSM reveals that reflectance of 0.4 to 0.6um channels of VIIRS degrades faster than the reflectance of longer wavelength RSB channels. A model is developed to derive characteristic parameters such as mean SD surface roughness height and autocovariance length of SD surface roughness from the long term spectral degradation of SD reflectance as monitored by SDSM. These two parameters are trended to assess development of surface roughness of the SD over the operation period of VIIRS.

  8. Biochemical traits and proteomic changes in postharvest flowers of medicinal chrysanthemum exposed to enhanced UV-B radiation.

    PubMed

    Yao, Xiaoqin; Chu, Jian-Zhou; Ma, Chun-Hui; Si, Chao; Li, Ji-Gang; Shi, Xiao-Fei; Liu, Chao-Nan

    2015-08-01

    The article studied UV-B effects on biochemical traits and proteomic changes in postharvest flowers of medicinal chrysanthemum. The experiment about UV-B effects on biochemical traits in flowers included six levels of UV-B treatments (0 (UV0), 50 (UV50), 200 (UV200), 400 (UV400), 600 (UV600) and 800 (UV800) μWcm(-2)). UV400, UV600 and UV800 treatments significantly increased the contents of hydrogen peroxide, malondialdehyde and UV-B absorbing compounds, and the activity of phenylalanine ammonia lyase enzyme over the control. The contents of chlorogenic acid and flavone in flowers were significantly increased by UV-B treatments (except for UV50 and UV800). Two-dimensional gel electrophoresis was utilized to analyze proteomic changes in flowers with or without UV-B radiation. Results indicated that 43 protein spots (>1.5-fold difference in volume) were detected, including 19 spots with a decreasing trend and 24 spots with an increasing trend, and 19 differentially expressed protein spots were successfully indentified by MALDI-TOF MS. The indentified proteins were classified based on functions, the most of which were involved in photosynthesis, respiration, protein biosynthesis and degradation and defence. An overall assessment using biochemical and differential proteomic data revealed that UV-B radiation could affect biochemical reaction and promote secondary metabolism processes in postharvest flowers. PMID:26114222

  9. Periscope antenna radiation - Sidelobes and diffuse lobes

    NASA Astrophysics Data System (ADS)

    Magne, P.; Bui-Hai, N.

    1980-06-01

    The radiation pattern of the periscope antenna, which consists of a parabolic dish on the ground and a passive tower-mounted reflector, is investigated in its entirety in order to facilitate the application of the configuration, which can eliminate the 5-10-dB losses associated with a waveguide connection in microwave systems. The radiation diagram is calculated based on the geometrical theory of diffraction, and measured for a periscope Cassegrain antenna with a gain of 47 dB and passive reflectors of various heights, dimensions and shapes in the millimeter wave range. Based on the results of the study, the design of an optimized periscope antenna with a classical tower is presented, and it is concluded that the periscope antenna can provide a radiation pattern compatible with intensive carrier frequency reuse

  10. The mechanisms of protection of antioxidants on Nostoc sphaeroides against UV-B radiation

    NASA Astrophysics Data System (ADS)

    Wang, G. H.

    UV radiation is one of space harmful factor for earth organisms in space exploration In the present work we studied on the role of antioxidant system in Nostoc sphaeroides K u tz Cyanobacteria and the effects of exogenous antioxidant molecules on its photosynthetic rate under UV-B radiation It was found that UV-B radiation decreased the photosynthetic activity of cyanobacterium but promoted the activity of antioxidant system to protect photosystem II PSII and exogenous antioxidant sodium nitroprusside SNP N-acetylcysteine NAC had an obvious protection on PSII activity under UV-B radiation The activity of SOD Superoxide Dismutase EC 1 15 1 1 CAT Catalase EC 1 11 1 6 POD Peroxidase EC 1 11 1 7 and content of MDA and ASC were improved by 0 5mM and 1mM SNP but 0 1mM SNP decreased the activity of antioxide system Exogenous NAC addition decreased the activity of SOD POD CAT and the content MDA and ASC but exogenous NAC addition increased the content of GSH The results suggested that exogenous SNP and NAC may protect algae by different mechanisms in which SNP maybe play double roles as sources of reactive free radicals or ROS scavengers in formation of algae s protection of PSII under UV-B radiation while NAC does function as antioxidant reagent or precursor of glutathione which could protect PSII directly from UV-B radiation Keyword antioxidant system exogenous or endogenous antioxidant Nostoc sphaeroides photosynthesis UV-B radiation

  11. Three-temperature plasma shock solutions with gray radiation diffusion

    NASA Astrophysics Data System (ADS)

    Johnson, B. M.; Klein, R. I.

    2016-04-01

    The effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation. Since the radiation heats the electrons on length scales that are much longer than the electron-ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.

  12. Three-temperature plasma shock solutions with gray radiation diffusion

    DOE PAGESBeta

    Johnson, Bryan M.; Klein, Richard I.

    2016-04-19

    Here we discuss the effects of radiation on the structure of shocks in a fully ionized plasma are investigated by solving the steady-state fluid equations for ions, electrons, and radiation. The electrons and ions are assumed to have the same bulk velocity but separate temperatures, and the radiation is modeled with the gray diffusion approximation. Both electron and ion conduction are included, as well as ion viscosity. When the material is optically thin, three-temperature behavior occurs. When the diffusive flux of radiation is important but radiation pressure is not, two-temperature behavior occurs, with the electrons strongly coupled to the radiation.more » Since the radiation heats the electrons on length scales that are much longer than the electron–ion Coulomb coupling length scale, these solutions resemble radiative shock solutions rather than plasma shock solutions that neglect radiation. When radiation pressure is important, all three components are strongly coupled. Results with constant values for the transport and coupling coefficients are compared to a full numerical simulation with a good match between the two, demonstrating that steady shock solutions constitute a straightforward and comprehensive verification test methodology for multi-physics numerical algorithms.« less

  13. UV-C radiation as a factor reducing microbiological contamination of fish meal.

    PubMed

    Skowron, Krzysztof; Bauza-Kaszewska, Justyna; Dobrzański, Zbigniew; Paluszak, Zbigniew; Skowron, Karolina Jadwiga

    2014-01-01

    Fish meals, added to feeds as a source of protein, may contain pathogenic bacteria. Therefore, effective methods for their sanitizing, such as UV-C radiation, are needed to minimize the epidemiological risk. The objective of this study was to evaluate the effect of UV-C radiation on the sanitary state of fish meals. The research materials included salmon and cod meals. Samples of the fish meals were inoculated with suspensions of Salmonella, E. coli, enterococci, and C. sporogenes spores and exposed to the following surface UV-C fluencies: 0-400 J·m⁻² for bacteria and 0-5000 J·m⁻² for spores. For the vegetative forms, the highest theoretical lethal UV-C dose, ranging from 670.99 to 688.36 J·m⁻² depending on the meal type, was determined for Salmonella. The lowest UV-C fluency of 363.34-363.95 J·m⁻² was needed for the inactivation of Enterococcus spp. Spores were considerably more resistant, and the UV-C doses necessary for inactivation were 159571.1 J·m⁻² in salmon meal and 66836.9 J·m⁻² in cod meal. The application of UV-C radiation for the sanitization of fish meals proved to be a relatively effective method for vegetative forms of bacteria but was practically ineffective for spores. PMID:24578670

  14. UV-C Radiation as a Factor Reducing Microbiological Contamination of Fish Meal

    PubMed Central

    Dobrzański, Zbigniew; Skowron, Karolina Jadwiga

    2014-01-01

    Fish meals, added to feeds as a source of protein, may contain pathogenic bacteria. Therefore, effective methods for their sanitizing, such as UV-C radiation, are needed to minimize the epidemiological risk. The objective of this study was to evaluate the effect of UV-C radiation on the sanitary state of fish meals. The research materials included salmon and cod meals. Samples of the fish meals were inoculated with suspensions of Salmonella, E. coli, enterococci, and C. sporogenes spores and exposed to the following surface UV-C fluencies: 0–400 J·m−2 for bacteria and 0–5000 J·m−2 for spores. For the vegetative forms, the highest theoretical lethal UV-C dose, ranging from 670.99 to 688.36 J·m−2 depending on the meal type, was determined for Salmonella. The lowest UV-C fluency of 363.34–363.95 J·m−2 was needed for the inactivation of Enterococcus spp. Spores were considerably more resistant, and the UV-C doses necessary for inactivation were 159571.1 J·m−2 in salmon meal and 66836.9 J·m−2 in cod meal. The application of UV-C radiation for the sanitization of fish meals proved to be a relatively effective method for vegetative forms of bacteria but was practically ineffective for spores. PMID:24578670

  15. ECOLOGICAL AND NONHUMAN BIOLOGICAL EFFECTS OF SOLAR UV-B RADIATION

    EPA Science Inventory

    Recent studies regarding the impact of UV-B radiation upon ecological and nonhuman biological systems is the subject of the report. For years scientists and laymen alike have causally noted the impact of solar ultraviolet radiation upon the non-human component of the biosphere. S...

  16. Differential responses of tetrasporophytes and gametophytes of Mazzaella laminarioides (Gigartinales, Rhodophyta) under solar UV radiation.

    PubMed

    Navarro, Nelso P; Figueroa, Félix L; Korbee, Nathalie; Mansilla, Andrés; Plastino, Estela M

    2016-06-01

    The effects of solar UV radiation on mycosporine-like amino acids (MAAs), growth, photosynthetic pigments (Chl a, phycobiliproteins), soluble proteins (SP), and C and N content of Mazzaella laminarioides tetrasporophytes and gametophytes were investigated. Apical segments of tetrasporophytes and gametophytes were exposed to solar radiation under three treatments (PAR [P], PAR+UVA [PA], and PAR+UVA+UVB [PAB]) during 18 d in spring 2009, Punta Arenas, Chile. Samples were taken after 2, 6, 12, and 18 d of solar radiation exposure. Most of the parameters assessed on M. laminarioides were significantly influenced by the radiation treatment, and both gametophytes and tetrasporophytes seemed to respond differently when exposed to high UV radiation. The two main effects promoted by UV radiation were: (i) higher synthesis of MAAs in gametophytes than tetrasporophytes at 2 d, and (ii) a decrease in phycoerythrin, phycocyanin, and SPs, but an increase in MAA content in tetrasporophytes at 6 and 12 d of culture. Despite some changes that were observed in biochemical parameters in both tetrasporophytes and gametophytes of M. laminarioides when exposed to UVB radiation, these changes did not promote deleterious effects that might interfere with the growth in the long term (18 d). The tolerance and resistance of M. laminarioides to higher UV irradiance were expected, as this intertidal species is exposed to variation in solar radiation, especially during low tide. PMID:26990026

  17. Effects of Stratospheric Ozone Depletion, Solar UV Radiation, and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

    EPA Science Inventory

    Climate change modulates the effects of solar UV radiation on biogeochemical cycles in terrestrial and aquatic ecosystems, particularly for carbon cycling, resulting in UV-mediated positive or negative feedbacks on climate. Possible positive feedbacks discussed in this assessment...

  18. Photoprotectant improves photostability and bioactivity of abscisic acid under UV radiation.

    PubMed

    Gao, Fei; Hu, Tanglu; Tan, Weiming; Yu, Chunxin; Li, Zhaohu; Zhang, Lizhen; Duan, Liusheng

    2016-05-01

    Photosensitivity causes serious drawback for abscisic acid (ABA) application, but preferable methods to stabilize the compound were not found yet. To select an efficient photoprotectant for the improvement of photostability and bioactivity of ABA when exposed to UV light, we tested the effects of a photostabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (HS-770) and two UV absorbers 2-hydroxy-4-n-octoxy-benzophenone (UV-531) and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP-4) with or without HS-770 on the photodegradation of ABA. Water soluble UV absorber BP-4 and oil soluble UV absorber UV-531 showed significant photo-stabilizing capability on ABA, possibly due to competitive energy absorption of UVB by the UV absorbers. The two absorbers showed no significant difference. Photostabilizer HS-770 accelerated the photodegradation of ABA and did not improve the photo-stabilizing capability of BP-4, likely due to no absorption in UVB region and salt formation with ABA and BP-4. Approximately 26% more ABA was kept when 280mg/l ABA aqueous solution was irradiated by UV light for 2h in the presence of 200mg/l BP-4. What's more, its left bioactivity on wheat seed (JIMAI 22) germination was greatly kept by BP-4, comparing to that of ABA alone. The 300 times diluent of 280mg/l ABA plus 200mg/l BP-4 after 2h irradiation showed more than 13% inhibition on shoot and root growth of wheat seed than that of ABA diluent alone. We concluded that water soluble UV absorber BP-4 was an efficient agent to keep ABA activity under UV radiation. The results could be used to produce photostable products of ABA compound or other water soluble agrichemicals which are sensitive to UV radiation. The frequencies and amounts of the agrichemicals application could be thereafter reduced. PMID:26963431

  19. Plant Responses to Increased UV-B Radiation: A Research Project

    NASA Technical Reports Server (NTRS)

    DAntoni, H. L.; Skiles, J. W.; Armstrong, R.; Coughlan, J.; Daleo, G.; Mayoral, A.; Lawless, James G. (Technical Monitor)

    1994-01-01

    Ozone decrease implies more ultraviolet-B (UV-B) radiation reaching the surface of the Earth. Increased UV-B radiation triggers responses by living organisms. Despite the large potential impacts on vegetation, little is known about UV-B effects on terrestrial ecosystems. Long-term ecological studies are needed to quantify the effects of increased UV radiation on terrestrial ecosystems, asses the risks, and produce reliable data for prediction. Screening pigments are part of one of the protective mechanism in plants. Higher concentrations of screening pigments in leaves may be interpreted as a response to increased UV radiation. If the screening effect is not sufficient, important molecules will be disturbed by incoming radiation. Thus, genetics, photosynthesis, growth, plant and leaf shape and size, and pollen grains may be affected. This will have an impact on ecosystem dynamics, structure and productivity. It is necessary to monitor selected terrestrial ecosystems to permit detection and interpretation of changes attributable to global climate change and depleted ozone shield. The objectives of this project are: (1) To identify and measure indicators of the effects of increased solar UV-B radiation on terrestrial plants; (2) to select indicators with the greatest responses to UV-B exposure; (3) to test, adapt or create ecosystem models that use the information gathered by this project for prediction and to enhance our understanding of the effects of increased UV-B radiation on terrestrial ecosystems. As a first step to achieve these objectives we propose a three-year study of forest and steppe vegetation on the North slope of the Brooks Range (within the Arctic circle, in Alaska), in the Saguaro National Monument (near Tucson, Arizona) and in the forests and steppes of Patagonia (Argentina). We selected (1) vegetation north of the Polar Circle because at 70N there is 8% risk of plant damage due to increased UV-B radiation; (2) the foothills of Catalina Mountains

  20. Directional Degradation of Spectralon Diffuser Under Ionizing Radiation for Calibration of Space-Based Sensors

    NASA Technical Reports Server (NTRS)

    Georgiev, G. T.; Butler, J. J.; Kowalewski, M. G.; Ding, L.

    2012-01-01

    Assessment of the effect of Vacuum Ultra Violet (VUV) irradiation on the Bidirectional Reflectance Distribution Function (BRDF) of Spectralon is presented in this paper. The sample was a 99% white Spectralon calibration standard irradiated with VUV source positioned at 60o off the irradiation direction for a total of 20 hours. The BRDF before and after VUV irradiation was measured and compared at number of wavelengths in the UV, VIS and IR. Non-isotropic directional degradation of Spectralon diffuser under ionizing radiation was detected at different BRDF measurement geometries primarily at UV spectral range. The 8o directional/hemispherical reflectance of the same sample was also measured and compared from 200nm to 2500nm. Index Terms BRDF, Reflectance, Multiangular, Spectralon, Remote Sensing

  1. European standards for protective apparel against UV radiation.

    PubMed

    Laperre, Jan; Foubert, Fred

    2002-01-01

    The first European standard which describes the test procedure to determine the UV-protection factor of clothing is about to be completed. A second part of the same standard, dealing with labelling and marking aspects, is ready to be submitted to public enquiry. In this effort a group of experts from most EU member states have cooperated with a high degree of consensus. In this chapter we explain this European standard together with the standard developed in the UK. PMID:12079233

  2. Rediscovering leaf optical properties: New insights into plant acclimation to solar UV radiation.

    PubMed

    Barnes, Paul W; Flint, Stephan D; Ryel, Ronald J; Tobler, Mark A; Barkley, Anne E; Wargent, Jason J

    2015-08-01

    The accumulation of UV-absorbing compounds (flavonoids and other phenylpropanoid derivatives) and resultant decrease in the UV transmittance of the epidermis in leaves (TUV), is a primary protective mechanism against the potentially deleterious effects of UV radiation and is a critical component of the overall acclimation response of plants to changing UV environments. Traditional measurements of TUV were laborious, time-consuming and destructive or invasive, thus limiting their ability to efficiently make multiple measurements of the optical properties of plants in the field. The development of rapid, nondestructive optical methods of determining TUV has permitted the examination of UV optical properties of leaves with increased replication, on a finer time scale, and enabled repeated sampling of the same leaf over time. This technology has therefore allowed for studies examining acclimation responses to UV in plants in ways not previously possible. Here we provide a brief review of these earlier studies examining leaf UV optical properties and some of their important contributions, describe the principles by which the newer non-invasive measurements of epidermal UV transmittance are made, and highlight several case studies that reveal how this technique is providing new insights into this UV acclimation response in plants, which is far more plastic and dynamic than previously thought. PMID:25465528

  3. Effects of solar UV radiation and climate change on biogeochemical cycling: Interactions and feedbacks

    SciTech Connect

    Erickson III, David J

    2011-01-01

    Solar UV radiation, climate and other drivers of global change are undergoing significant changes and models forecast that these changes will continue for the remainder of this century. Here we assess the effects of solar UV radiation on biogeochemical cycles and the interactions of these effects with climate change, including feedbacks on climate. Such interactions occur in both terrestrial and aquatic ecosystems. While there is significant uncertainty in the quantification of these effects, they could accelerate the rate of atmospheric CO{sub 2} increase and subsequent climate change beyond current predictions. The effects of predicted changes in climate and solar UV radiation on carbon cycling in terrestrial and aquatic ecosystems are expected to vary significantly between regions. The balance of positive and negative effects on terrestrial carbon cycling remains uncertain, but the interactions between UV radiation and climate change are likely to contribute to decreasing sink strength in many oceanic regions. Interactions between climate and solar UV radiation will affect cycling of elements other than carbon, and so will influence the concentration of greenhouse and ozone-depleting gases. For example, increases in oxygen-deficient regions of the ocean caused by climate change are projected to enhance the emissions of nitrous oxide, an important greenhouse and ozone-depleting gas. Future changes in UV-induced transformations of aquatic and terrestrial contaminants could have both beneficial and adverse effects. Taken in total, it is clear that the future changes in UV radiation coupled with human-caused global change will have large impacts on biogeochemical cycles at local, regional and global scales.

  4. Effects of solar UV radiation and climate change on biogeochemical cycling: interactions and feedbacks.

    PubMed

    Zepp, R G; Erickson, D J; Paul, N D; Sulzberger, B

    2011-02-01

    Solar UV radiation, climate and other drivers of global change are undergoing significant changes and models forecast that these changes will continue for the remainder of this century. Here we assess the effects of solar UV radiation on biogeochemical cycles and the interactions of these effects with climate change, including feedbacks on climate. Such interactions occur in both terrestrial and aquatic ecosystems. While there is significant uncertainty in the quantification of these effects, they could accelerate the rate of atmospheric CO(2) increase and subsequent climate change beyond current predictions. The effects of predicted changes in climate and solar UV radiation on carbon cycling in terrestrial and aquatic ecosystems are expected to vary significantly between regions. The balance of positive and negative effects on terrestrial carbon cycling remains uncertain, but the interactions between UV radiation and climate change are likely to contribute to decreasing sink strength in many oceanic regions. Interactions between climate and solar UV radiation will affect cycling of elements other than carbon, and so will influence the concentration of greenhouse and ozone-depleting gases. For example, increases in oxygen-deficient regions of the ocean caused by climate change are projected to enhance the emissions of nitrous oxide, an important greenhouse and ozone-depleting gas. Future changes in UV-induced transformations of aquatic and terrestrial contaminants could have both beneficial and adverse effects. Taken in total, it is clear that the future changes in UV radiation coupled with human-caused global change will have large impacts on biogeochemical cycles at local, regional and global scales. PMID:21253663

  5. Analytic expressions for ULF wave radiation belt radial diffusion coefficients

    PubMed Central

    Ozeke, Louis G; Mann, Ian R; Murphy, Kyle R; Jonathan Rae, I; Milling, David K

    2014-01-01

    We present analytic expressions for ULF wave-derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer data, and compressional magnetic field power from in situ measurements. We show that the overall electric and magnetic diffusion coefficients are to a good approximation both independent of energy. We present example 1-D radial diffusion results from simulations driven by CRRES-observed time-dependent energy spectra at the outer boundary, under the action of radial diffusion driven by the new ULF wave radial diffusion coefficients and with empirical chorus wave loss terms (as a function of energy, Kp and L). There is excellent agreement between the differential flux produced by the 1-D, Kp-driven, radial diffusion model and CRRES observations of differential electron flux at 0.976 MeV—even though the model does not include the effects of local internal acceleration sources. Our results highlight not only the importance of correct specification of radial diffusion coefficients for developing accurate models but also show significant promise for belt specification based on relatively simple models driven by solar wind parameters such as solar wind speed or geomagnetic indices such as Kp. Key Points Analytic expressions for the radial diffusion coefficients are presented The coefficients do not dependent on energy or wave m value The electric field diffusion coefficient dominates over the magnetic PMID:26167440

  6. Effects of temperature and UV radiation increases on the photosynthetic efficiency in four scleractinian coral species.

    PubMed

    Ferrier-Pagès, Christine; Richard, Cécile; Forcioli, Didier; Allemand, Denis; Pichon, Michel; Shick, J Malcolm

    2007-08-01

    Experiments were performed on coral species containing clade A (Stylophora pistillata, Montipora aequituberculata) or clade C (Acropora sp., Pavona cactus) zooxanthellae. The photosynthetic efficiency (F(v)/F(m)) of the corals was first assessed during a short-term increase in temperature (from 27 degrees C to 29 degrees C, 32 degrees C, and 34 degrees C) and acute exposure to UV radiation (20.5 W m(-2) UVA and 1.2 W m(-2) UVB) alone or in combination. Increasing temperature to 34 degrees C significantly decreased the F(v)/F(m) in S. pistillata and M. aequituberculata. Increased UV radiation alone significantly decreased the F(v)/F(m) of all coral species, even at 27 degrees C. There was a combined effect of temperature and UV radiation, which reduced F(v)/F(m) in all corals by 25% to 40%. During a long-term exposure to UV radiation (17 days) the F(v)/F(m) was significantly reduced after 3 days' exposure in all species, which did not recover their initial values, even after 17 days. By this time, all corals had synthesized mycosporine-like amino acids (MAAs). The concentration and diversity of MAAs differed among species, being higher for corals containing clade A zooxanthellae. Prolonged exposure to UV radiation at the nonstressful temperature of 27 degrees C conferred protection against independent, thermally induced photoinhibition in all four species. PMID:17679722

  7. UV-B Radiation Impacts Shoot Tissue Pigment Composition in Allium fistulosum L. Cultigens

    PubMed Central

    Abney, Kristin R.; Kopsell, Dean A.; Sams, Carl E.; Zivanovic, Svetlana; Kopsell, David E.

    2013-01-01

    Plants from the Allium genus are valued worldwide for culinary flavor and medicinal attributes. In this study, 16 cultigens of bunching onion (Allium fistulosum L.) were grown in a glasshouse under filtered UV radiation (control) or supplemental UV-B radiation [7.0 μmol·m−2·s−2 (2.68 W·m−2)] to determine impacts on growth, physiological parameters, and nutritional quality. Supplemental UV-B radiation influenced shoot tissue carotenoid concentrations in some, but not all, of the bunching onions. Xanthophyll carotenoid pigments lutein and β-carotene and chlorophylls a and b in shoot tissues differed between UV-B radiation treatments and among cultigens. Cultigen “Pesoenyj” responded to supplemental UV-B radiation with increases in the ratio of zeaxanthin + antheraxanthin to zeaxanthin + antheraxanthin + violaxanthin, which may indicate a flux in the xanthophyll carotenoids towards deepoxydation, commonly found under high irradiance stress. Increases in carotenoid concentrations would be expected to increase crop nutritional values. PMID:23606817

  8. Theoretical and Numerical Investigation of Radiative Extinction of Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Ray, Anjan

    1996-01-01

    The influence of soot radiation on diffusion flames was investigated using both analytical and numerical techniques. Soot generated in diffusion flames dominate the flame radiation over gaseous combustion products and can significantly lower the temperature of the flame. In low gravity situations there can be significant accumulation of soot and combustion products in the vicinity of the primary reaction zone owing to the absence of any convective buoyant flow. Such situations may result in substantial suppression of chemical activities in a flame, and the possibility of a radiative extinction may also be anticipated. The purpose of this work was to not only investigate the possibility of radiative extinction of a diffusion flame but also to qualitatively and quantitatively analyze the influence of soot radiation on a diffusion flame. In this study, first a hypothetical radiative loss profile of the form of a sech(sup 2) was assumed to influence a pure diffusion flame. It was observed that the reaction zone can, under certain circumstances, move through the radiative loss zone and locate itself on the fuel side of the loss zone contrary to our initial postulate. On increasing the intensity and/or width of the loss zone it was possible to extinguish the flame, and extinction plots were generated. In the presence of a convective flow, however, the movement of the temperature and reaction rate peaks indicated that the flame behavior is more complicated compared to a pure diffusional flame. A comprehensive model of soot formation, oxidation and radiation was used in a more involved analysis. The soot model of Syed, Stewart and Moss was used for soot nucleation and growth and the model of Nagle and Strickland-Constable was used for soot oxidation. The soot radiation was considered in the optically thin limit. An analysis of the flame structure revealed that the radiative loss term is countered both by the reaction term and the diffusion term. The essential balance for

  9. Stability of Stationary Solutions of the Multifrequency Radiation Diffusion Equations

    SciTech Connect

    Hald, O H; Shestakov, A I

    2004-01-20

    A nondimensional model of the multifrequency radiation diffusion equation is derived. A single material, ideal gas, equation of state is assumed. Opacities are proportional to the inverse of the cube of the frequency. Inclusion of stimulated emission implies a Wien spectrum for the radiation source function. It is shown that the solutions are uniformly bounded in time and that stationary solutions are stable. The spatially independent solutions are asymptotically stable, while the spatially dependent solutions of the linearized equations approach zero.

  10. Diffuse gamma radiation. [intensity, energy spectrum and spatial distribution from SAS 2 observations

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1978-01-01

    Results are reported for an investigation of the intensity, energy spectrum, and spatial distribution of the diffuse gamma radiation detected by SAS 2 away from the galactic plane in the energy range above 35 MeV. The gamma-ray data are compared with relevant data obtained at other wavelengths, including 21-cm emission, radio continuum radiation, and the limited UV and radio information on local molecular hydrogen. It is found that there are two quite distinct components to the diffuse radiation, one of which shows a good correlation with the galactic matter distribution and continuum radiation, while the other has a much steeper energy spectrum and appears to be isotropic at least on a coarse scale. The galactic component is interpreted in terms of its implications for both local and more distant regions of the Galaxy. The apparently isotropic radiation is discussed partly with regard to the constraints placed on possible models by the steep energy spectrum, the observed intensity, and an upper limit on the anisotropy.

  11. Short- and long-term physiological responses of grapevine leaves to UV-B radiation.

    PubMed

    Martínez-Lüscher, J; Morales, F; Delrot, S; Sánchez-Díaz, M; Gomés, E; Aguirreolea, J; Pascual, I

    2013-12-01

    The present study aimed at evaluating the short- and long-term effects of UV-B radiation on leaves of grapevine Vitis vinifera (cv. Tempranillo). Grapevine fruit-bearing cuttings were exposed to two doses of supplemental biologically effective UV-B radiation (UV-BBE) under glasshouse-controlled conditions: 5.98 and 9.66kJm(-2)d(-1). The treatments were applied either for 20d (from mid-veraison to ripeness) or 75d (from fruit set to ripeness). A 0kJm(-2)d(-1) UV-B treatment was included as control. The main effects of UV-B were observed after the short-term exposure (20d) to 9.66kJm(-2)d(-1). Significant decreases in net photosynthesis, stomatal conductance, sub-stomatal CO2 concentration, the actual photosystem II (PSII) efficiency, total soluble proteins and de-epoxidation state of the VAZ cycle were observed, whereas the activities of several antioxidant enzymes increased significantly. UV-B did not markedly affect dark respiration, photorespiration, the maximum potential PSII efficiency (Fv/Fm), non-photochemical quenching (NPQ), as well as the intrinsic PSII efficiency. However, after 75d of exposure to 5.98and 9.66kJm(-2)d(-1) UV-B most photosynthetic and biochemical variables were unaffected and there were no sign of oxidative damage in leaves. The results suggest a high long-term acclimation capacity of grapevine to high UV-B levels, associated with a high accumulation of UV-B absorbing compounds in leaves, whereas plants seemed to be tolerant to moderate doses of UV-B. PMID:24157214

  12. Long-Term Dosimetry of Solar UV Radiation in Antarctica with Spores of Bacillus subtilis

    PubMed Central

    Puskeppeleit, Monika; Quintern, Lothar E.; el Naggar, Saad; Schott, Jobst-Ulrich; Eschweiler, Ute; Horneck, Gerda; Bücker, Horst

    1992-01-01

    The main objective was to assess the influence of the seasonal stratospheric ozone depletion on the UV climate in Antarctica by using a biological test system. This method is based on the UV sensitivity of a DNA repair-deficient strain of Bacillus subtilis (TKJ 6321). In our field experiment, dried layers of B. subtilis spores on quartz discs were exposed in different seasons in an exposure box open to solar radiation at the German Antarctic Georg von Neumayer Station (70°37′S, 8°22′W). The UV-induced loss of the colony-forming ability was chosen as the biological end point and taken as a measure for the absorbed biologically harmful UV radiation. Inactivation constants were calculated from the resulting dose-response curves. The results of field experiments performed in different seasons indicate a strongly season-dependent trend of the daily UV-B level. Exposures performed at extremely depleted ozone concentrations (October 1990) gave higher biologically harmful UV-B levels than expected from the calculated season-dependent trend, which was determined at normal ozone values. These values were similar to values which were measured during the Antarctic summer, indicating that the depleted ozone column thickness has an extreme influence on the biologically harmful UV climate on ground. PMID:16348742

  13. The effect of UV-B radiation on chloroplast translation in Pisum sativum

    SciTech Connect

    Raab, M.M.; Jagendorf, A.T. )

    1990-05-01

    UV-B radiation has previously been reported to reduce growth, flowering, and net photosynthesis. The present study examines the effect of UV-B radiation on isolated chloroplast of 7-10 day old pea seedlings. Amount of ({sup 3}H)-Leu incorporated into isolated chloroplasts was measured in the presence or absence of UV-B exposure. Preliminary experiments show a 30% inhibition of protein synthesis in isolated chloroplasts after only 20 mins of UV-B exposure (6.9 J/m{sup 2}/30 min). Percent inhibition of chloroplast translation is directly correlated with UV-B exposure over a 60 min time span. Preliminary studies also show no change in both cold and radiolabeled protein profiles as expressed on 1-D PAGE and autofluorography. Comparative studies on the sensitivity of e{sup {minus}} flow vs protein synthesis following UV-B exposure are underway. Further work on the role of oxygen free radicals and the specific site of action of UV-B damage to the translation machinery of chloroplasts will be discussed.

  14. Action spectrum and mechanisms of UV radiation-induced injury in lupus erythematosus

    SciTech Connect

    Kochevar, I.E.

    1985-07-01

    Photosensitivity associated with lupus erythematosus (LE) is well established. The photobiologic basis for this abnormal response to ultraviolet radiation, however, has not been determined. This paper summarizes the criteria for elucidating possible photobiologic mechanisms and reviews the literature relevant to the mechanism of photosensitivity in LE. In patients with LE, photosensitivity to wavelengths shorter than 320 nm has been demonstrated; wavelengths longer than 320 nm have not been adequately evaluated. DNA is a possible chromophore for photosensitivity below 320 nm. UV irradiation of skin produces thymine photodimers in DNA. UV-irradiated DNA is more antigenic than native DNA and the antigenicity of UV-irradiated DNA has been proposed, but not proven, to be involved in the development of clinical lesions. UV irradiation of mice previously injected with anti-UV-DNA antibodies produces Ig deposition and complement fixation that appears to be similar to the changes seen in lupus lesions. Antibodies to UV-irradiated DNA occur in the serum of LE patients although a correlation between antibody titers and photosensitivity was not observed. Defective repair of UV-induced DNA damage does not appear to be a mechanism for the photosensitivity in LE. Other mechanisms must also be considered. The chromophore for photosensitivity induced by wavelengths longer than 320 nm has not been investigated in vivo. In vitro studies indicate that 360-400 nm radiation activates a photosensitizing compound in the lymphocytes and serum of LE patients and causes chromosomal aberrations and cell death. The mechanism appears to involve superoxide anion.

  15. Kinetics of avoidance of simulated solar uv radiation by two arthropods

    SciTech Connect

    Barcelo, J.A.; Calkins, J.

    1980-12-01

    There is an increasing likelihood that the solar uv-B radiation (lambda = 280-320 nm) reaching the earth's surface will increase due to depletion of the stratospheric ozone layer. It is recognized that many organisms are insufficiently resistant to solar uv-B to withstand full summer sunlight and thus mechanisms which facilitate avoidance of solar uv-B exposure may have significance for the survival of sensitive species. There are many alternative pathways which would lead to avoidance of solar uv-B. We have investigated the dynamics of biological reactions to simulated solar uv-B radiation in two small arthropods, the two-spotted spider mite Tetranychus urticae Koch and the aquatic copepod Cyclops serrulatus. Observations of positioning and rate of movement were made; a mathematical formalism was developed which assisted in interpretation of the observations. Our observations suggest that, although avoidance would mitigate increased solar uv-B effects, even organisms which specifically reduce their uv-B exposure would encounter additional stress if ozone depletion does occur.

  16. Long-term dosimetry of solar UV radiation in Antarctica with spores of Bacillus subtilis

    SciTech Connect

    Puskeppeleit, M.; Quintern, L.E.; Naggar, S. el; Schott, J.U.; Eschweiler, U.; Horneck, G.; Buecker, H. )

    1992-08-01

    The main objective was to assess the influence of the seasonal stratospheric ozone depletion on the UV climate in Antarctica by using a biological test system. This method is based on the UV sensitivity of a DNA repair-deficient (TKJ 6321). In the field experiment, dried layers of B. subtilis spores on quartz discs were exposed in different seasons in an exposure box open to solar radiation at the German Antarctic Georg von Neumayer Station (70[degree]37[prime]S, 8[degree]22[prime]W). The UV-induced loss of the colony-forming ability was chosen as the biological end point and taken as a measure for the absorbed biologically harmful UV radiation. Inactivation constants were calculated from the resulting dose-response curves. The results of field experiments performed in different seasons indicate a strongly season-dependent trend of the daily UV-B level. Exposures performed at extremely depleted ozone concentrations gave higher biologically harmful UV-B levels than expected from the calculated season-dependent trend, which was determined at normal ozone values. These values were similar to values which were measured during the Antarctic summer, indicating that the depleted ozone column thickness has an extreme influence on the biologically harmful UV climate on ground.

  17. Long-Term Dosimetry of Solar UV Radiation in Antarctica with Spores of Bacillus subtilis.

    PubMed

    Puskeppeleit, M; Quintern, L E; El Naggar, S; Schott, J U; Eschweiler, U; Horneck, G; Bücker, H

    1992-08-01

    The main objective was to assess the influence of the seasonal stratospheric ozone depletion on the UV climate in Antarctica by using a biological test system. This method is based on the UV sensitivity of a DNA repair-deficient strain of Bacillus subtilis (TKJ 6321). In our field experiment, dried layers of B. subtilis spores on quartz discs were exposed in different seasons in an exposure box open to solar radiation at the German Antarctic Georg von Neumayer Station (70 degrees 37'S, 8 degrees 22'W). The UV-induced loss of the colony-forming ability was chosen as the biological end point and taken as a measure for the absorbed biologically harmful UV radiation. Inactivation constants were calculated from the resulting dose-response curves. The results of field experiments performed in different seasons indicate a strongly season-dependent trend of the daily UV-B level. Exposures performed at extremely depleted ozone concentrations (October 1990) gave higher biologically harmful UV-B levels than expected from the calculated season-dependent trend, which was determined at normal ozone values. These values were similar to values which were measured during the Antarctic summer, indicating that the depleted ozone column thickness has an extreme influence on the biologically harmful UV climate on ground. PMID:16348742

  18. Radiative Extinction of Gaseous Spherical Diffusion Flames in Microgravity

    NASA Technical Reports Server (NTRS)

    Santa, K. J.; Chao, B. H.; Sunderland, P. B.; Urban, D. L.; Stocker, D. P.; Axelbaum, R. L.

    2007-01-01

    Radiative extinction of spherical diffusion flames was investigated experimentally and numerically. The experiments involved microgravity spherical diffusion flames burning ethylene and propane at 0.98 bar. Both normal (fuel flowing into oxidizer) and inverse (oxidizer flowing into fuel) flames were studied, with nitrogen supplied to either the fuel or the oxygen. Flame conditions were chosen to ensure that the flames extinguished within the 2.2 s of available test time; thus extinction occurred during unsteady flame conditions. Diagnostics included color video and thin-filament pyrometry. The computations, which simulated flow from a porous sphere into a quiescent environment, included detailed chemistry, transport and radiation, and yielded transient results. Radiative extinction was observed experimentally and simulated numerically. Extinction time, peak temperature, and radiative loss fraction were found to be independent of flow rate except at very low flow rates. Radiative heat loss was dominated by the combustion products downstream of the flame and was found to scale with flame surface area, not volume. For large transient flames the heat release rate also scaled with surface area and thus the radiative loss fraction was largely independent of flow rate. Peak temperatures at extinction onset were about 1100 K, which is significantly lower than for kinetic extinction. One observation of this work is that while radiative heat losses can drive transient extinction, this is not because radiative losses are increasing with time (flame size) but rather because the heat release rate is falling off as the temperature drops.

  19. Effect of Elevated CO2, O3, and UV Radiation on Soils

    PubMed Central

    Rejšek, Klement; Vranová, Valerie

    2014-01-01

    In this work, we have attempted to review the current knowledge on the impact of elevated CO2, O3, and UV on soils. Elevated CO2 increases labile and stabile soil C pool as well as efficiency of organic pollutants rhizoremediation and phytoextraction of heavy metals. Conversely, both elevated O3 and UV radiation decrease inputs of assimilates to the rhizosphere being accompanied by inhibitory effects on decomposition processes, rhizoremediation, and heavy metals phytoextraction efficiency. Contrary to elevated CO2, O3, or UV-B decreases soil microbial biomass, metabolisable C, and soil Nt content leading to higher C/N of soil organic matter. Elevated UV-B radiation shifts soil microbial community and decreases populations of soil meso- and macrofauna via direct effect rather than by induced changes of litter quality and root exudation as in case of elevated CO2 or O3. CO2 enrichment or increased UV-B is hypothesised to stimulate or inhibit both plant and microbial competitiveness for soluble soil N, respectively, whereas O3 favours only microbial competitive efficiency. Understanding the consequences of elevated CO2, O3, and UV radiation for soils, especially those related to fertility, phytotoxins inputs, elements cycling, plant-microbe interactions, and decontamination of polluted sites, presents a knowledge gap for future research. PMID:24688424

  20. Effect of elevated CO2, O3, and UV radiation on soils.

    PubMed

    Formánek, Pavel; Rejšek, Klement; Vranová, Valerie

    2014-01-01

    In this work, we have attempted to review the current knowledge on the impact of elevated CO2, O3, and UV on soils. Elevated CO2 increases labile and stabile soil C pool as well as efficiency of organic pollutants rhizoremediation and phytoextraction of heavy metals. Conversely, both elevated O3 and UV radiation decrease inputs of assimilates to the rhizosphere being accompanied by inhibitory effects on decomposition processes, rhizoremediation, and heavy metals phytoextraction efficiency. Contrary to elevated CO2, O3, or UV-B decreases soil microbial biomass, metabolisable C, and soil N t content leading to higher C/N of soil organic matter. Elevated UV-B radiation shifts soil microbial community and decreases populations of soil meso- and macrofauna via direct effect rather than by induced changes of litter quality and root exudation as in case of elevated CO2 or O3. CO2 enrichment or increased UV-B is hypothesised to stimulate or inhibit both plant and microbial competitiveness for soluble soil N, respectively, whereas O3 favours only microbial competitive efficiency. Understanding the consequences of elevated CO2, O3, and UV radiation for soils, especially those related to fertility, phytotoxins inputs, elements cycling, plant-microbe interactions, and decontamination of polluted sites, presents a knowledge gap for future research. PMID:24688424

  1. An assessment of ozone levels, UV radiation and their occupational health hazard estimation during photocopying operation.

    PubMed

    Singh, Bhupendra Pratap; Kumar, Amit; Singh, Deepak; Punia, Monika; Kumar, Krishan; Jain, Vinod Kumar

    2014-06-30

    This study investigates the levels of ozone concentration along with an ultraviolet (UV) and visible spectral radiation at eight photocopy centers in an academic institute, Delhi. Sampling was done in two types of locations, i.e., basement photocopy centers (BPC) and ground floor photocopy centers (GPC) for 8h. Measurements of levels of ozone, UV and visible radiation were done by ozone analyzer, UV radiometer and Field spectra instrument, respectively. Results show that the hourly mean concentration of ozone was observed to be in the range of 1.8-10.0 ppb and 5.3-45.8 ppb for BPC and GPC, respectively. In terms UV radiations, energy lies between 5.0×10(-3) and 7.0×10(-3) mW/cm(2) for ultraviolet A (UVA), 1.0×10(-3) and 2.0×10(-3) mW/cm(2) for ultraviolet B (UVB) and 6.0×10(-3) and 8.0×10(-3) mW/cm(2) for ultraviolet C (UVC). Correlation between the UV radiations and ozone production observed was statistically insignificant. To know the health hazard occurred to the workers, the standard erythema dose (SED) value was calculated for emitting UV radiation. The SED was estimated to be in the range of 0.02-0.04 and 0.02-0.32 for direct and indirect methods which is less than the guideline prescribed by Commission Internationale del' Eclairage (CIE). In nutshell, person involved in photocopy operation for their livelihood must be trained and should have knowledge for the long term gradual build up health problems due to ozone and UV production from photocopier. The manufactures should be ultimated with the significant ozone production, so that photocopier machine can be redesigned. PMID:24857892

  2. RecBC enzyme overproduction affects UV and gamma radiation survival of Deinococcus radiodurans.

    PubMed

    Khairnar, Nivedita P; Kamble, Vidya A; Misra, Hari S

    2008-01-01

    Deinococcus radiodurans recovering from the effect of acute dose of gamma (gamma) radiation shows a biphasic mechanism of DNA double strands breaks repair that involves an efficient homologous recombination. However, it shows higher sensitivity to near-UV (NUV) than Escherichia coli and lacks RecBC, a DNA strand break (DSB) repair enzyme in some bacteria. Recombinant Deinococcus expressing the recBC genes of E. coli showed nearly three-fold improvements in near-UV tolerance and nearly 2 log cycle reductions in wild type gamma radiation resistance. RecBC over expression effect on radiation response of D. radiodurans was independent of indigenous RecD. Loss of gamma radiation tolerance was attributed to the enhanced rate of in vivo degradation of radiation damaged DNA and delayed kinetics of DSB repair during post-irradiation recovery. RecBC expressing cells of Deinococcus showed wild type response to Far-UV. These results suggest that the overproduction of RecBC competes with the indigenous mechanism of gamma radiation damaged DNA repair while it supports near-UV tolerance in D. radiodurans. PMID:17720630

  3. Diffusion approximation for modeling of 3-D radiation distributions

    SciTech Connect

    Zardecki, A.; Gerstl, S.A.W.; De Kinder, R.E. Jr.

    1985-01-01

    A three-dimensional transport code DIF3D, based on the diffusion approximation, is used to model the spatial distribution of radiation energy arising from volumetric isotropic sources. Future work will be concerned with the determination of irradiances and modeling of realistic scenarios, relevant to the battlefield conditions. 8 refs., 4 figs.

  4. Implicit solution of large-scale radiation diffusion problems

    SciTech Connect

    Brown, P N; Graziani, F; Otero, I; Woodward, C S

    2001-01-04

    In this paper, we present an efficient solution approach for fully implicit, large-scale, nonlinear radiation diffusion problems. The fully implicit approach is compared to a semi-implicit solution method. Accuracy and efficiency are shown to be better for the fully implicit method on both one- and three-dimensional problems with tabular opacities taken from the LEOS opacity library.

  5. Design of autotrack detecting instrument for solar UV radiation

    NASA Astrophysics Data System (ADS)

    Xia, Jiangtao; Mao, Xiaoli; Zhao, Jing

    2009-11-01

    In order to autotrack the object and detect the solar UV index, a reliable real-time high-precise instrument is proposed in this paper. This instrument involves two subsystems: the autotrack and detecting modules. The autotrack module consists of four-quadrant photo detector, multi-channel signal processing circuit and precise stepping system. The detecting module designed for dada measurement and acquisition is made up of the ultraviolet sensor UV460 and high precision A/D converter MAX1162. The key component of the entire instrument is ultralow-power microprocessor MSP430 which is used for entire system controlling and data processing. The lower system of autotracking and measurement is communicated with upper PC computer by RS232 module. In the experiment, the tracking precision of two-dimensional motion revolving stage is calibrated to be less than 0.05°. Experimental results indicate that the system designed could realize the precise autotracking and detecting function well, and the measure precision of system has reached the desirable target.

  6. Isoprene emission from a subarctic peatland under enhanced UV-B radiation.

    PubMed

    Tiiva, Päivi; Rinnan, Riikka; Faubert, Patrick; Räsänen, Janne; Holopainen, Toini; Kyrö, Esko; Holopainen, Jarmo K

    2007-01-01

    Isoprene is a reactive hydrocarbon with an important role in atmospheric chemistry, and emissions from vegetation contribute to atmospheric carbon fluxes. The magnitude of isoprene emissions from arctic peatlands is not known, and it may be altered by increasing UV-B radiation. Isoprene emission was measured with the dynamic chamber method from a subarctic peatland under long-term enhancement of UV-B radiation targeted to correspond to a 20% loss in the stratospheric ozone layer. The site type of the peatland was a flark fen dominated by the moss Warnstorfia exannulata and sedges Eriophorum russeolum and Carex limosa. The relationship between species densities and the emission was also assessed. Isoprene emissions were significantly increased by enhanced UV-B radiation during the second (2004) and the fourth (2006) growing seasons under the UV-B exposure. Emissions were related to the density of E. russeolum. The dominant moss, W. exannulata, proved to emit small amounts of isoprene in a laboratory trial. Subarctic fens, even without Sphagnum moss, are a significant source of isoprene to the atmosphere, especially under periods of warm weather. Warming of the Arctic together with enhanced UV-B radiation may substantially increase the emissions. PMID:17888116

  7. Exobiology at Southern Brazil: Spore Dosimetry and the UV Solar Radiation

    NASA Astrophysics Data System (ADS)

    Rampelotto, P. H.; Rosa, M. B.; Schuch, N. J.; Pinheiro, D. K.; Schuch, A. P.; Munakata, N.

    2009-12-01

    The ultraviolet - UV is considered the range of solar radiation most immediately lethal to the life organisms on the Earth’s surface. In this context, since 2000, the monitoring of the biologically-effective solar radiation using spore dosimeter at the Southern Space Observatory (29.4° S, 53.8° W), South of Brazil, has been performed. The biological dosimeter is based in the spore inactivation doses of Bacillus subtilis strain TKJ6312, who is sensitive to the UV solar radiation. Monthly expositions of biological dosimeter have been compared with solar irradiance obtained by Brewer spectrophotometer. Correlations indices about r > 0.86 shows the potential applicability of the biosensor in the monitoring of biologically-effective solar radiation. Since spores are stabile microorganisms, considering extreme environment variations, the biosensor may be used for studies of the effects of the solar radiation in others planetary environments for future work.

  8. Dependence of erythemally weighted UV radiation on geographical parameters in the United States

    NASA Astrophysics Data System (ADS)

    Wang, Xinli; Gao, Wei; Davis, John; Olson, Becky; Janson, George; Slusser, James

    2007-09-01

    The relationship between solar ultraviolet (UV) radiation reaching the Earth's surface and geographical parameters is helpful in estimating the spatial distribution of UV radiation, which provides useful information to evaluate the potential impacts of enhanced UV levels on human health, agriculture, environment, and ecosystems for sustainable development. Measurements of erythemally weighted UV radiation at the sites of the United States Department of Agriculture UV-B Monitoring and Research Program (UVBMRP) monitoring network were analyzed to investigate the geographical distribution and seasonal variations. Twenty nine observation sites, which had continuous measurements during the recent six years, are selected for this study; twenty seven of them are distributed in the United States, including one in Hawaii and one in Alaska, and two of them are located in Canada along the United States border. The measurements were taken using the Yankee Environmental Systems Inc. (YES) UVB-1 ultraviolet pyranometer. This work focuses the data from the recent six years of 2001-2006 and the measurements during summer months (June-August) are emphasized. For each day, the measurements are integrated from sunrise to sunset to produce the daily UV dosage, which is then averaged for different seasons or for the whole year over the six years to generate the average daily UV dosage. A multivariable regression technique is exploited to characterize the dependence of UV dosages on geographical parameters, including latitude and altitude. The results show that, although there are many factors, such as clouds, ozone, aerosols, air pollutants, and haze, that affect the UV radiation intensity at a location, the latitude and altitude of the site are the primary factors that regulate the average daily UV dosage. On average over the last six years in the United States, more than 95% of the variability in averaged daily UV dosages can be explained by the latitude and altitude. Longitude is

  9. Radiative acceleration of tritium diffusion in LiF crystals

    SciTech Connect

    Andronikashvili, E.L.; Tsetskhladze, T.V.; Emel'yanov, K.A.

    1980-10-01

    The results of an experimental investigation of radiative acceleration of tritium diffusion previously irradiated in LiF crystals in the nuclear radiation field of a reactor are described. It has been discovered that, at a temperature of --100 /sup 0/C and higher, tritium liberation is observed. The rate of this process is not subject to Fick's law and varies nonmonotonically in time. It is suggested from the data of a microcalorimetric investigation of LiF crystals irradiated under various conditions that the combined action of radiative and thermal annealing determines the nature of the dependence of the tritium liberation rate on the temperature of irradiation by fast neutrons.

  10. Comparison of the Radiative Two-Flux and Diffusion Approximations

    NASA Technical Reports Server (NTRS)

    Spuckler, Charles M.

    2006-01-01

    Approximate solutions are sometimes used to determine the heat transfer and temperatures in a semitransparent material in which conduction and thermal radiation are acting. A comparison of the Milne-Eddington two-flux approximation and the diffusion approximation for combined conduction and radiation heat transfer in a ceramic material was preformed to determine the accuracy of the diffusion solution. A plane gray semitransparent layer without a substrate and a non-gray semitransparent plane layer on an opaque substrate were considered. For the plane gray layer the material is semitransparent for all wavelengths and the scattering and absorption coefficients do not vary with wavelength. For the non-gray plane layer the material is semitransparent with constant absorption and scattering coefficients up to a specified wavelength. At higher wavelengths the non-gray plane layer is assumed to be opaque. The layers are heated on one side and cooled on the other by diffuse radiation and convection. The scattering and absorption coefficients were varied. The error in the diffusion approximation compared to the Milne-Eddington two flux approximation was obtained as a function of scattering coefficient and absorption coefficient. The percent difference in interface temperatures and heat flux through the layer obtained using the Milne-Eddington two-flux and diffusion approximations are presented as a function of scattering coefficient and absorption coefficient. The largest errors occur for high scattering and low absorption except for the back surface temperature of the plane gray layer where the error is also larger at low scattering and low absorption. It is shown that the accuracy of the diffusion approximation can be improved for some scattering and absorption conditions if a reflectance obtained from a Kubelka-Munk type two flux theory is used instead of a reflection obtained from the Fresnel equation. The Kubelka-Munk reflectance accounts for surface reflection and

  11. Reconstruction of past and prediction of future erythemal UV-radiation at two sites in Austria

    NASA Astrophysics Data System (ADS)

    Weihs, Philipp; Rieder, Harald; Wagner, Jochen; Simic, Stana; Dameris, Martin

    2010-05-01

    Since the discovery of anthropogenic ozone depletion more than 30 year ago, the scientific community has shown an increasing interest in UV-B radiation and started to monitor UV-radiation. However, difficulties involved in the routine operation and maintenance of the instruments have limited the length of reliable data records to about two decades. Further the number of places where they were measured, result in a set of observations too short and too sparse for a good understanding of past UV changes. Moreover state of the art climate models do not calculate future scenarios of UV-doses. Therefore detailed information about past and future UV-trends are lacking. Reconstruction techniques are indispensable to derive long-term time series of UV-radiation and fill this gap. Apart from the astronomical parameters, like solar zenith angle and sun-earth-distance, UV radiation is strongly influenced by clouds, ozone and surface albedo. We developed and evaluated a reconstruction technique for UV-doses (from regional climate model output) that first calculates the UV-doses under clear-sky condition and afterwards applies corrections in order to take cloud effects into account. Since the input parameters cloud cover, total ozone column and surface albedo are available from the Regional Climate Models REMO and E39/C (DLR-model), we applied our reconstruction technique for the past and for future scenarios using REMO and E39/C data as input. Hence we simulated a seamless UV long-term time series from the past to the future. Our method was applied for the high alpine station Hoher Sonnblick (3106m) situated in the Austrian Alps and for Vienna (170m) in the Eastern part of the Austrian territory. We first analyse the accuracy of the obtained backward reconstruction and intercompare the modelled and measured input parameters ozone, cloud modification factor, and ground albedo. Several approaches to improve the accuracy of the reconstruction are presented. Then we present the

  12. Crystallinity and vinyl groups formation in polyethylene films exposed to UV-B radiation

    NASA Astrophysics Data System (ADS)

    Martínez-Romo, A.; González-Mota, R.; Soto-Bernal, J. J.; Frausto-Reyes, C.; Rosales-Candelas, I.; Muñoz-Campos, E. I.

    2011-10-01

    Polyethylene (PE), is a polymer formed by carbon-carbon single bonds, is a very stable material with a very slow degradation rate. In this paper, polyethylene films bag type were exposed to UV-B radiation (320-280 nm) at different exposure times (2 to 12 days). The UV radiation effects on PE samples were characterized using infrared spectroscopy with attenuated total reflectance (ATR). The vinyl group formation indicates the PE degradation. These chemical groups have IR absorption in 900-1300 cm-1; additionally the degree of crystallinity increase with the increasing of the exposure time. The experiment showed significant changes in PE molecular structure.

  13. Protection of photosystem II against UV-A and UV-B radiation in the cyanobacterium Plectonema boryanum: the role of growth temperature and growth irradiance.

    PubMed

    Ivanov, A G; Miskiewicz, E; Clarke, A K; Greenberg, B M; Huner, N P

    2000-12-01

    Plectonema boryanum UTEX 485 cells were grown at 29 degrees C and 150 mumol m-2 s-1 photosynthetically active radiation (PAR) and exposed to PAR combined with ultraviolet-A radiation (UV-A) at 15 degrees C. This induced a time-dependent inhibition of photosystem II (PSII) photochemistry measured as a decrease of the chlorophyll a fluorescence ratio, Fv/Fm, to 50% after 2 h of UV-A treatment compared to nontreated control cells. Exposure of the same cells to PAR combined with UV-A + ultraviolet-B radiation (UV-B) caused only a 30% inhibition of PSII photochemistry relative to nontreated cells. In contrast, UV-A and UV-A + UV-B irradiation of cells cultured at 15 degrees C and 150 mumol m-2 s-1 had minimal effects on the Fv/Fm values. However, cells grown at 15 degrees C and lower PAR irradiance (6 mumol m-2 s-1) exhibited similar inhibition patterns of PSII photochemistry as control cells. The decreased sensitivity of PSII photochemistry of P. boryanum grown at 15 degrees C and 150 mumol m-2 s-1 to subsequent exposure to UV radiation relative to either control cells or cells grown at low temperature but low irradiance was correlated with the following: (1) a reduced efficiency of energy transfer to PSII reaction centers; (2) higher levels of a carotenoid tentatively identified as myxoxanthophyll; (3) the accumulation of scytonemin and mycosporine amino acids; and (4) the accumulation of ATP-dependent caseinolytic proteases. Thus, acclimation of P. boryanum at low temperature and moderate irradiance appears to confer significant resistance to UV-induced photoinhibition of PSII. The role of excitation pressure in the induction of this resistance to UV radiation is discussed. PMID:11140265

  14. Inactivation of Single-Celled Ascaris suum Eggs by Low-Pressure UV Radiation

    PubMed Central

    Brownell, Sarah A.; Nelson, Kara L.

    2006-01-01

    Intact and decorticated single-celled Ascaris suum eggs were exposed to UV radiation from low-pressure, germicidal lamps at fluences (doses) ranging from 0 to 8,000 J/m2 for intact eggs and from 0 to 500 J/m2 for decorticated eggs. With a UV fluence of 500 J/m2, 0.44- ± 0.20-log inactivation (mean ± 95% confidence interval) (63.7%) of intact eggs was observed, while a fluence of 4,000 J/m2 resulted in 2.23- ± 0.49-log inactivation (99.4%). (The maximum quantifiable inactivation was 2.5 log units.) Thus, according to the methods used here, Ascaris eggs are the most UV-resistant water-related pathogen identified to date. For the range of fluences recommended for disinfecting drinking water and wastewater (200 to 2,000 J/m2), from 0- to 1.5-log inactivation can be expected, although at typical fluences (less than 1,000 J/m2), the inactivation may be less than 1 log. When the eggs were decorticated (the outer egg shell layers were removed with sodium hypochlorite, leaving only the lipoprotein ascaroside layer) before exposure to UV, 1.80- ± 0.32-log reduction (98.4%) was achieved with a fluence of 500 J/m2, suggesting that the outer eggshell layers protected A. suum eggs from inactivation by UV radiation. This protection may have been due to UV absorption by proteins in the outer layers of the 3- to 4-μm-thick eggshell. Stirring alone (without UV exposure) also inactivated some of the Ascaris eggs (∼20% after 75 min), which complicated determination of the inactivation caused by UV radiation alone. PMID:16517669

  15. Cutaneous vitamin D synthesis versus skin cancer development: The Janus faces of solar UV-radiation.

    PubMed

    Reichrath, Jörg; Nürnberg, Bernd

    2009-09-01

    In scientific and public communities, there is an ongoing discussion how to balance between positive and negative effects of solar UV-exposure. On the one hand, solar UV-radiation represents the most important environmental risk factor for the development of non-melanoma skin cancer. Consequently, UV protection is an important measure to prevent these malignancies, especially in risk groups. Otherwise, approximately 90% of all vitamin D needed by the human body has to be formed in the skin through the action of UV-radiation. This dilemma represents a serious problem, for an association of vitamin D-deficiency and multiple independent diseases including various types of cancer, bone diseases, autoimmune diseases, infectious diseases, cardiovascular diseases and hypertension has now been reported in a large number of investigative and epidemiologic studies. As a consequence, it has been assumed that for the general population in the US, Europe and other countries, the net effects of solar UV B-radiation on human health are beneficial at or near current levels. We and others have shown that strict sun protection causes vitamin D-deficiency/insufficiency and that detection and treatment of vitamin D-deficiency in sun deprived risk groups is of high importance. Although further work is necessary to define an adequate vitamin D-status and adequate guidelines for solar and artificial UV-exposure, it is at present mandatory that public health campaigns and sun protection recommendations to prevent skin cancer consider these facts. In this review, we analyze the present literature to help developing well-balanced recommendations on sun protection that ensure an adequate vitamin D-status. These recommendations will hopefully protect us against adverse effects of UV protection without significantly increasing the risk to develop UV-induced skin cancer. PMID:20808512

  16. Researchers lack data on trends in UV radiation at Earth's surface

    SciTech Connect

    Zurer, P.S.

    1993-07-26

    Current anxiety about depletion of stratospheric ozone stems from the expected resulting increase in biologically damaging ultraviolet (UV) radiation at Earth's surface. Atmospheric ozone absorbs sunlight with wavelengths shorter than 320 nm--the highest-energy UV-B wavelengths (280-320 nm) that can damage DNA in living systems. But surprisingly, despite firm evidence the ozone layer is being eroded by chlorine and bromine from man-made compounds, very little information exists on how UV light intensity is changing. Solid data from Antarctica reveal that UV radiation soars under the ozone hole, where fully half of the atmospheric ozone is destroyed each spring. But elsewhere on the globe, where ozone has been thinning at a rate of a few percent per decade, the corresponding trends in UV intensity are not at all clear. In the late 1970s and early 1980s the problem of ozone depletion seemed solved. The US had banned the use of chlorofluorocarbons (CFCs) in aerosols. Model calculations were predicting CFCs would cause only a small loss of ozone by the second half of the 21st century. Costly monitoring of UV radiation commanded little attention. Attitudes began to change with the 1985 discovery of the Antarctic ozone hole. The National Science Foundation (NSF) established UV monitoring stations in the Antarctic in 1988, adding an Alaskan station in 1990. Both the Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) have programs in the works that will eventually place monitoring stations across the US, but it will be many years before researchers have access to the kind of extensive database necessary to reliably evaluation long-term trends in UV intensity.

  17. UV Radiation: a new first year physics/life sciences laboratory experiment

    NASA Astrophysics Data System (ADS)

    Petelina, S. V.; Siddaway, J. M.

    2010-12-01

    Unfortunately, Australia leads the world in the number of skin cancer cases per capita. Three major factors that contribute to this are: 1) the level of damaging ultraviolet (UV) radiation in Australia is higher than in many other countries. This is caused, among other factors, by the stratospheric ozone depletion and Antarctic ozone hole; 2) many people in Australia are of Irish-Scottish origin and their skin can not repair the damage caused by the UV radiation as effectively as the skin of people of other origins; 3) Australia is one of the world’s leaders in the outdoor activities where people tend to spend more time outside. As our experience has shown, most Australian University students, high school students, and even high school teachers were largely unaware of the UV damage details and effective safety measures. Therefore, a need for new ways to educate people became apparent. The general aim of this new 1st year laboratory experiment, developed and first offered at La Trobe University (Melbourne, Australia) in 2009, is to investigate how UV-B radiation levels change under various solar illumination conditions and how effective different types of protection are. After pre-lab readings on physical concepts and biological effects of UV radiation, and after solving all pre-lab problems, the students go outside and measure the actual change in UV-B and UV-A radiation levels under various conditions. Some of these conditions are: direct sun, shade from a building, shade under the roof, reflection from various surfaces, direct sun through cheap and expensive sunglasses and eyeglasses, direct sun through various types of cloth and hair. The equipment used is the UV-Probe manufactured by sglux SolGel Technologies GmbH. The students’ feedback on this new laboratory experiment was very positive. It was ranked top among all physics experiments offered as part of that subject (Physics for Life Sciences) in 2009 and top among all physics experiments presented for

  18. UPDATE ON COORDINATED STUDIES OF AMPHIBIAN DISTRIBUTIONS AND UV RADIATION

    EPA Science Inventory

    In February of 2000 researchers from the EPA, the National Park Service, other governmental agencies, and academia formulated a plan for coordinated studies of amphibian distributions and aquatic ultraviolet radiation exposure risks in several national parks. At this point we hav...

  19. Simulation of increasing UV radiation as a consequence of ozone depletion

    NASA Astrophysics Data System (ADS)

    Diaz, Susana B.; Camilion, Carolina; Lacoste, Karine; Escobar, Julio; Demers, Serge; Gianesella, Sonia M. F.; Roy, Suzanne

    2003-11-01

    UV plays a key roll in several biological functions. As consequence of the ozone depletion investigations to study the effects of UV radiation on human health and terrestrial and aquatic ecosystems have been carried out in laboratories and in the field. Experiments performed in laboratories, irradiating samples with lamps often present the inconvenience that light sources do not reproduce properly the solar spectrum. Field experiments are usually carried out comparing samples exposed to ambient irradiance (normal or increased) against 100% UV-B screened samples. This scenario also differs from the real situation of normal irradiance against UV-B increased irradiance. Some authors have solved this problem performing studies under ambient conditions, simulating the ozone depletion by supplementation of the UV-B radiation with lamps. As part of the IAI CNR-26, "Enhanced Ultraviolet-B Radiation in Natural Ecosystems as an added Perturbation due to Ozone Depletion," mesocosms experiments were performed at Rimouski, Canada), Ubatuba (Brasil) and Ushuaia, Argentina) using the supplementing methodology. In this paper we introduce the design of the measurements and lamps setting and the methodology used to calculate the attenuation constant and the irradiance at the water column at the mesocosms during the experiment, emphasizing on the Ubatuba campaign.

  20. Global forecast model to predict the daily dose of the solar erythemally effective UV radiation.

    PubMed

    Schmalwieser, Alois W; Schauberger, Günther; Janouch, Michal; Nunez, Manuel; Koskela, Tapani; Berger, Daniel; Karamanian, Gabriel

    2005-01-01

    A worldwide forecast of the erythemally effective ultraviolet (UV) radiation is presented. The forecast was established to inform the public about the expected amount of erythemally effective UV radiation for the next day. Besides the irradiance, the daily dose is forecasted to enable people to choose the appropriate sun protection tools. Following the UV Index as the measure of global erythemally effective irradiance, the daily dose is expressed in units of UV Index hours. In this study, we have validated the model and the forecast against measurements from broadband UV radiometers of the Robertson-Berger type. The measurements were made at four continents ranging from the northern polar circle (67.4 degrees N) to the Antarctic coast (61.1 degrees S). As additional quality criteria the frequency of underestimation was taken into account because the forecast is a tool of radiation protection and made to avoid overexposure. A value closer than one minimal erythemal dose for the most sensitive skin type 1 to the observed value was counted as hit and greater deviations as underestimation or overestimation. The Austrian forecast model underestimates the daily dose in 3.7% of all cases, whereas 1.7% results from the model and 2.0% from the assumed total ozone content. The hit rate could be found in the order of 40%. PMID:15453822

  1. Involvement of pnp in survival of UV radiation in Escherichia coli K-12.

    PubMed

    Rath, Devashish; Mangoli, Suhas H; Pagedar, Amruta R; Jawali, Narendra

    2012-05-01

    Polynucleotide phosphorylase (PNPase), a multifunctional protein, is a 3'→5' exoribonuclease or exoDNase in the presence of inorganic phosphate (P(i)), and extends a 3'-OH of RNA or ssDNA in the presence of ADP or dADP. In Escherichia coli, PNPase is known to protect against H(2)O(2)- and mitomycin C-induced damage. Recent reports show that Bacillus subtilis PNPase is required for repair of H(2)O(2)-induced double-strand breaks. Here we show that absence of PNPase makes E. coli cells sensitive to UV, indicating that PNPase has a role in survival of UV radiation damage. Analyses of various DNA repair pathways show that in the absence of nucleotide excision repair, survival of UV radiation depends critically on PNPase function. Consequently, uvrA pnp, uvrB pnp and uvrC pnp strains show hypersensitivity to UV radiation. Whereas the pnp mutation is non-epistatic to recJ, recQ and recG mutations with respect to the UV-sensitivity phenotype, it is epistatic to uvrD, recB and ruvA mutations, implicating it in the recombinational repair process. PMID:22322961

  2. Does enhanced solar UV-B radiation affect marine primary producers in their natural habitats?

    PubMed

    Häder, Donat-P

    2011-01-01

    This article is a highlight of the paper by Li et al. in this issue of Photochemistry and Photobiology as well as a short summary of the research on the effects of solar UV-B radiation on primary production in the oceans. Laboratory experiments under controlled conditions using artificial light sources indicate species-specific damage of many phytoplankton groups. Mesocosm studies in enclosures of limited volume allow analyzing UV effects in multigeneration monitoring of natural assemblages. Field studies to determine the effects of short-wavelength solar radiation require sensitive instrumentation and measurements over extended areas of the open ocean to yield significant results. Results from a cruise described in the paper by Li et al. indicate clear effects of UV-B and UV-A on the photosynthetic carbon fixation of phytoplankton communities with spatial differences between coastal and open-ocean waters. Increasing temperatures and acidification in the ocean due to global climate change may exacerbate the detrimental effects of solar UV-B radiation. PMID:21208211

  3. The PUR Experiment on the EXPOSE-R facility: biological dosimetry of solar extraterrestrial UV radiation

    NASA Astrophysics Data System (ADS)

    Bérces, A.; Egyeki, M.; Fekete, A.; Horneck, G.; Kovács, G.; Panitz, C.

    2015-01-01

    The aim of our experiment Phage and Uracil Response was to extend the use of bacteriophage T7 and uracil biological dosimeters for measuring the biologically effective ultraviolet (UV) dose in the harsh extraterrestrial radiation conditions. The biological detectors were exposed in vacuum-tightly cases in the European Space Agency (ESA) astrobiological exposure facility attached to the external platform of Zvezda (EXPOSE-R). EXPOSE-R took off to the International Space Station (ISS) in November 2008 and was installed on the External platform of the Russian module Zvezda of the ISS in March 2009. Our goal was to determine the dose-effect relation for the formation of photoproducts (i.e. damage to phage DNA and uracil, respectively). The extraterrestrial solar UV radiation ranges over the whole spectrum from vacuum-UV (λ<200 nm) to UVA (315 nm<λ<400 nm), which causes photolesions (photoproducts) in the nucleic acids/their components either by photoionization or excitation. However, these wavelengths cause not only photolesions but in a wavelength-dependent efficiency the reversion of some photolesions, too. Our biological detectors measured in situ conditions the resultant of both reactions induced by the extraterrestrial UV radiation. From this aspect the role of the photoreversion in the extension of the biological UV dosimetry are discussed.

  4. Effects of UV-A Radiation on Desmodesmus armatus: Changes in Growth Rate, Pigment Content and Morphological Appearance

    NASA Astrophysics Data System (ADS)

    Pálffy, Károly; Vörös, Lajos

    2006-10-01

    Laboratory cultures of Desmodesmus armatus (R. Chod.) Hegew. were grown under different levels of photosynthetically active radiation (PAR) supplemented with 3.75 mW . cm-2 UV-A radiation. Growth rate was monitored daily, chlorophyl-a concentration, total carotenoid content, cell number and the relative abundance of different coenobial forms was determined at the end of each experiment. Exposure to UV-A radiation resulted in an increasing inhibition of growth towards higher PAR levels, reaching 100% at 400 μmol . m-2 . s-1. Cellular carotenoid content was higher in the presence of UV-A radiation, on the other hand no differences were observed in cellular chlorophyll-a concentration. UV-A radiation also induced changes in coenobium formation with a decreasing proportion of 4-celled coenobia and an increase in the abundance of 2-celled and teratologic coenobia, suggesting that high intensity UV-A radiation may influence cell cycle events or morphology development.

  5. UV radiation-induced immunosuppression is greater in men and prevented by topical nicotinamide.

    PubMed

    Damian, Diona L; Patterson, Clare R S; Stapelberg, Michael; Park, Joohong; Barnetson, Ross St C; Halliday, Gary M

    2008-02-01

    UV radiation-induced immunosuppression augments cutaneous carcinogenesis. The incidence of skin cancer continues to increase despite increased use of sunscreens, which are less effective at preventing immunosuppression than sunburn. Using the Mantoux reaction as a model of skin immunity, we investigated the effects of solar-simulated (ss) UV and its component UVA and UVB wavebands and tested the ability of topical nicotinamide to protect from UV-induced immunosuppression. Healthy, Mantoux-positive volunteers were UV-irradiated on their backs, with 5% nicotinamide or vehicle applied to different sites in a randomized, double-blinded manner. Subsequent Mantoux testing at irradiated and adjacent unirradiated sites enabled measurement of UV-induced immunosuppression with and without nicotinamide. Suberythemal ssUV caused significant immunosuppression, although component UVB and UVA doses delivered independently did not. Men were immunosuppressed by ssUV doses three times lower than those required to immunosuppress women. This may be an important cause of the higher skin cancer incidence and mortality observed in men. Topical nicotinamide prevented immunosuppression, with gene chip microarrays suggesting that the mechanisms of protection may include alterations in complement, energy metabolism and apoptosis pathways. Nicotinamide is a safe and inexpensive compound that could be added to sunscreens or after-sun lotions to improve protection from immunosuppression. immunosuppression.JID JOURNAL CLUB ARTICLE: For questions, answers, and open discussion about this article, please go to http://network.nature.com/group/jidclub PMID:17882270

  6. The diffusion approximation. An application to radiative transfer in clouds

    NASA Technical Reports Server (NTRS)

    Arduini, R. F.; Barkstrom, B. R.

    1976-01-01

    It is shown how the radiative transfer equation reduces to the diffusion equation. To keep the mathematics as simple as possible, the approximation is applied to a cylindrical cloud of radius R and height h. The diffusion equation separates in cylindrical coordinates and, in a sample calculation, the solution is evaluated for a range of cloud radii with cloud heights of 0.5 km and 1.0 km. The simplicity of the method and the speed with which solutions are obtained give it potential as a tool with which to study the effects of finite-sized clouds on the albedo of the earth-atmosphere system.

  7. Fires increase Amazon forest productivity through increases in diffuse radiation

    NASA Astrophysics Data System (ADS)

    Rap, A.; Spracklen, D. V.; Mercado, L.; Reddington, C. L.; Haywood, J. M.; Ellis, R. J.; Phillips, O. L.; Artaxo, P.; Bonal, D.; Restrepo Coupe, N.; Butt, N.

    2015-06-01

    Atmospheric aerosol scatters solar radiation increasing the fraction of diffuse radiation and the efficiency of photosynthesis. We quantify the impacts of biomass burning aerosol (BBA) on diffuse radiation and plant photosynthesis across Amazonia during 1998-2007. Evaluation against observed aerosol optical depth allows us to provide lower and upper BBA emissions estimates. BBA increases Amazon basin annual mean diffuse radiation by 3.4-6.8% and net primary production (NPP) by 1.4-2.8%, with quoted ranges driven by uncertainty in BBA emissions. The enhancement of Amazon basin NPP by 78-156 Tg C a-1 is equivalent to 33-65% of the annual regional carbon emissions from biomass burning. This NPP increase occurs during the dry season and acts to counteract some of the observed effect of drought on tropical production. We estimate that 30-60 Tg C a-1 of this NPP enhancement is within woody tissue, accounting for 8-16% of the observed carbon sink across mature Amazonian forests.

  8. Radiation from Gas-Jet Diffusion Flames in Microgravity Environments

    NASA Technical Reports Server (NTRS)

    Bahadori, M. Yousef; Edelman, Raymond B.; Sotos, Raymond G.; Stocker, Dennis P.

    1991-01-01

    This paper presents the first demonstration of quantitative flame-radiation measurement in microgravity environments, with the objective of studying the influences and characteristics of radiative transfer on the behavior of gas-jet diffusion flames with possible application to spacecraft fire detection. Laminar diffusion flames of propane, burning in quiescent air at atmospheric pressure, are studied in the 5.18-Second Zero-Gravity Facility of NASA Lewis Research Center. Radiation from these flames is measured using a wide-view angle, thermopile-detector radiometer, and comparisons are made with normal-gravity flames. The results show that the radiation level is significantly higher in microgravity compared to normal-gravity environments due to larger flame size, enhanced soot formation, and entrapment of combustion products in the vicinity of the flame. These effects are the consequences of the removal of buoyancy which makes diffusion the dominant mechanism of transport. The results show that longer test times may be needed to reach steady state in microgravity environments.

  9. Effects of UV-B radiation on tetraspores of Chondrus ocellatus Holm (Rhodophyta), and effects of red and blue light on repair of UV-B-induced damage

    NASA Astrophysics Data System (ADS)

    Ju, Qing; Xiao, Hui; Wang, You; Tang, Xuexi

    2015-05-01

    We evaluated the effects of red and blue light on the repair of UV-B radiation-induced damage in tetraspores of Chondrus ocellatus Holm. Tetraspores of C. ocellatus were treated with different UV-B radiation levels (0, 36, 72, 108, 144 and 180 J/m2), and thereafter subjected to PAR, darkness, or red or blue light during a 2-h repair stage, each day for 48 days. The diameters and cellular contents of cyclobutane pyrimidine dimmers (CPDs), chlorophyll a (Chl a), phycoerythrin, and UV-B-absorbing mycosporinelike amino acids (MAAs) contents of the tetraspores were determined. Our results show that low doses of UV-B radiation (36 and 72 J/m2) promoted the growth of C. ocellatus; however, increased UV-B radiation gradually reduced the C. ocellatus growth (greater than 72 J/m2). The MAAs (palythine and asterina-330) in C. ocellatus were detected and analyzed by LC/MS. Our results suggest that moderate red light could induce the growth of this alga in aquaculture. In addition, photorepair was inhibited by red light, so there may be some other DNA repair mechanism activated by red light. Blue light promoted the activity of DNA photolyase, greatly improving remediation efficiency. Red and blue lights were found to reduce the capacity of C. ocellatus to form MAAs. Therefore, PAR, red light, and blue light play different roles during the repair processes for damage induced by UV-B radiation.

  10. Inactivation of Feline Calicivirus and Adenovirus Type 40 by UV Radiation

    PubMed Central

    Thurston-Enriquez, Jeanette A.; Haas, Charles N.; Jacangelo, Joseph; Riley, Kelley; Gerba, Charles P.

    2003-01-01

    Little information regarding the effectiveness of UV radiation on the inactivation of caliciviruses and enteric adenoviruses is available. Analysis of human calicivirus resistance to disinfectants is hampered by the lack of animal or cell culture methods that can determine the viruses' infectivity. The inactivation kinetics of enteric adenovirus type 40 (AD40), coliphage MS-2, and feline calicivirus (FCV), closely related to the human caliciviruses based on nucleic acid organization and capsid architecture, were determined after exposure to low-pressure UV radiation in buffered demand-free (BDF) water at room temperature. In addition, UV disinfection experiments were also carried out in treated groundwater with FCV and AD40. AD40 was more resistant than either FCV or coliphage MS-2 in both BDF water and groundwater. The doses of UV required to achieve 99% inactivation of AD40, coliphage MS-2, and FCV in BDF water were 109, 55, and 16 mJ/cm2, respectively. The doses of UV required to achieve 99% inactivation of AD40, coliphage MS-2, and FCV in groundwater were slightly lower than those in BDF water. FCV was inactivated by 99% by 13 mJ/cm2 in treated groundwater. A dose of 103 mJ/cm2 was required for 99% inactivation of AD40 in treated groundwater. The results of this study indicate that if FCV is an adequate surrogate for human caliciviruses, then their inactivation by UV radiation is similar to those of other single-stranded RNA enteric viruses, such as poliovirus. In addition, AD40 appears to be more resistant to UV disinfection than previously reported. PMID:12514044

  11. Validity of satellite measurements used for the monitoring of UV radiation risk on health

    NASA Astrophysics Data System (ADS)

    Jégou, F.; Godin-Beekman, S.; Corrêa, M. P.; Brogniez, C.; Auriol, F.; Peuch, V. H.; Haeffelin, M.; Pazmino, A.; Saiag, P.; Goutail, F.; Mahé, E.

    2011-06-01

    In order to test the validity of ultraviolet index (UVI) satellite products and UVI model simulations for general public information, intercomparison involving three satellite instruments (SCIAMACHY, OMI and GOME-2), the Chemistry and Transport Model, Modélisation de la Chimie Atmosphérique Grande Echelle (MOCAGE), and ground-based instruments was performed in 2008 and 2009. The intercomparison highlighted a systematic high bias of ~1 UVI in the OMI clear-sky products compared to the SCIAMACHY and TUV model clear-sky products. The OMI and GOME-2 all-sky products are close to the ground-based observations with a low 6 % positive bias, comparable to the results found during the satellite validation campaigns. This result shows that OMI and GOME-2 all-sky products are well appropriate to evaluate the UV-risk on health. The study has pointed out the difficulty to take into account either in the retrieval algorithms or in the models, the large spatial and temporal cloud modification effect on UV radiation. This factor is crucial to provide good quality UV information. OMI and GOME-2 show a realistic UV variability as a function of the cloud cover. Nevertheless these satellite products do not sufficiently take into account the radiation reflected by clouds. MOCAGE numerical forecasts show good results during periods with low cloud covers, but are actually not adequate for overcast conditions; this is why Météo-France currently uses human-expertised cloudiness (rather than direct outputs from Numerical Prediction Models) together with MOCAGE clear-sky UV indices for its operational forecasts. From now on, the UV monitoring could be done using free satellite products (OMI, GOME-2) and operational forecast for general public by using modelling, as long as cloud forecasts and the parametrisation of the impact of cloudiness on UV radiation are adequate.

  12. Validity of satellite measurements used for the monitoring of UV radiation risk on health

    NASA Astrophysics Data System (ADS)

    Jégou, F.; Godin-Beekman, S.; Corrêa, M. P.; Brogniez, C.; Auriol, F.; Peuch, V. H.; Haeffelin, M.; Pazmino, A.; Saiag, P.; Goutail, F.; Mahé, E.

    2011-12-01

    In order to test the validity of ultraviolet index (UVI) satellite products and UVI model simulations for general public information, intercomparison involving three satellite instruments (SCIAMACHY, OMI and GOME-2), the Chemistry and Transport Model, Modélisation de la Chimie Atmosphérique Grande Echelle (MOCAGE), and ground-based instruments was performed in 2008 and 2009. The intercomparison highlighted a systematic high bias of ~1 UVI in the OMI clear-sky products compared to the SCIAMACHY and TUV model clear-sky products. The OMI and GOME-2 all-sky products are close to the ground-based observations with a low 6 % positive bias, comparable to the results found during the satellite validation campaigns. This result shows that OMI and GOME-2 all-sky products are well appropriate to evaluate the UV-risk on health. The study has pointed out the difficulty to take into account either in the retrieval algorithms or in the models, the large spatial and temporal cloud modification effect on UV radiation. This factor is crucial to provide good quality UV information. OMI and GOME-2 show a realistic UV variability as a function of the cloud cover. Nevertheless these satellite products do not sufficiently take into account the radiation reflected by clouds. MOCAGE numerical forecasts show good results during periods with low cloud covers, but are actually not adequate for overcast conditions; this is why Météo-France currently uses human-expertised cloudiness (rather than direct outputs from Numerical Prediction Models) together with MOCAGE clear-sky UV indices for its operational forecasts. From now on, the UV monitoring could be done using free satellite products (OMI, GOME-2) and operational forecast for general public by using modelling, as long as cloud forecasts and the parametrisation of the impact of cloudiness on UV radiation are adequate.

  13. Colour change evaluation on UV radiation exposure for Păun-Repedea calcareous geomaterial

    NASA Astrophysics Data System (ADS)

    Pelin, V.; Sandu, I.; Munteanu, M.; Iurcovschi, C. T.; Gurlui, S.; Sandu, AV; Vasilache, V.; Brȃnzilă, M.; Sandu, I. G.

    2016-06-01

    When talking about the preservation treatments that can be applied to natural stones used in different constructions, the surface hydrophobization plays an important part, especially when referring to porous surfaces like the calcareous oolithic stones specific to Repedea area, Iasi County, Romania. The present paper presents a method that evaluates the hydrophobization efficiency of two types of pellicles, involving UV artificial ageing and colorimetric analysis of the treated surfaces. The evaluation was done through continuous colorimetric monitoring and by comparing the evolution of the chromatic modifications of the two treated surfaces with the original colorimetric values and with the witness area, which was exposed to UV radiations under the same conditions, but left chemical untreated. The techniques used during this experiment were: CIE L*a*b* colorimetry, OM, SEM-EDX, UV radiation exposure and Spectrum Irradiance Measurement.

  14. Radiation-damage-induced phasing: a case study using UV irradiation with light-emitting diodes.

    PubMed

    de Sanctis, Daniele; Zubieta, Chloe; Felisaz, Franck; Caserotto, Hugo; Nanao, Max H

    2016-03-01

    Exposure to X-rays, high-intensity visible light or ultraviolet radiation results in alterations to protein structure such as the breakage of disulfide bonds, the loss of electron density at electron-rich centres and the movement of side chains. These specific changes can be exploited in order to obtain phase information. Here, a case study using insulin to illustrate each step of the radiation-damage-induced phasing (RIP) method is presented. Unlike a traditional X-ray-induced damage step, specific damage is introduced via ultraviolet light-emitting diodes (UV-LEDs). In contrast to UV lasers, UV-LEDs have the advantages of small size, low cost and relative ease of use. PMID:26960126

  15. Application of CCD array digital fiber optic spectrometers in determination of within-tree and within-canopy irradiances of UV-B radiation

    NASA Astrophysics Data System (ADS)

    Beneski, Erin; Bassman, John H.; Slusser, James R.; Gao, Wei

    2005-08-01

    Although our understanding of the effects of UV-B radiation on annual and crop plants has improved considerably over the past three decades, knowledge of effects on perennial plants, particularly trees, remains much more limited. Understanding the effects of enhanced UV-B radiation on forest trees has been hampered by an inability to develop realistic dose-response relationships, which in turn, has resulted from lack of instrumentation sufficient to accurately determine biologically effective UV irradiances within the canopy. Traditional spectroradiometers equipped with spherical domes have sensor heads that are too large to make within-canopy measurements, especially at individual leaf locations or other small targets. Broad-band sensors, which are smaller, lack the wavelength discrimination necessary to calculate biological effective UV-B radiation. Measurement of UV radiation above a plant canopy provides little information about the radiation environment of individual leaves within the canopy. This is important because whole plant response to UV-radiation is an integrated response of all of the leaves, though obviously not all leaves contribute equally. Within leaves, stress stimuli may induce compensatory responses in unaffected portions of the same leaf, in other adjacent leaves, and even in remote leaves. It is not known if this is true for W radiation; the only way of finding out is to have a probe small enough to measure diminutive and precise locations within the canopy. In this study a StellarNet EPP2000C spectrometer equipped with a 400 μm optical fiber and Teflon diffuser was used to determine solar UV-B irradiances above and within the canopy of representative forest trees. Data was collected at different times during the day, for equivalent leaf and canopy positions in several representative trees. Data collected in the open and below-canopy positions are compared with an Optronics OL-754 spectroradiometer and data obtained at the USDA UVB

  16. Influence of radiation damage on krypton diffusion in silicon carbide

    NASA Astrophysics Data System (ADS)

    Friedland, E.; Hlatshwayo, T. T.; van der Berg, N. G.; Mabena, M. C.

    2015-07-01

    Diffusion of krypton in poly and single crystalline silicon carbide is investigated and compared with the previously obtained results for xenon, which pointed to a different diffusion mechanism than observed for chemically active elements. For this purpose 360 keV krypton ions were implanted in commercial 6H-SiC and CVD-SiC wafers at room temperature, 350 °C and 600 °C. Width broadening of the implantation profiles and krypton retention during isochronal and isothermal annealing up to temperatures of 1400 °C was determined by RBS-analysis, whilst in the case of 6H-SiC damage profiles were simultaneously obtained by α-particle channeling. Little diffusion and no krypton loss was detected in the initially amorphized and eventually recrystallized surface layer of cold implanted 6H-SiC during annealing up to 1200 °C. Above that temperature thermal etching of the implanted surface became increasingly important. No diffusion or krypton loss is detected in the hot implanted 6H-SiC samples during annealing up to 1400 °C. Radiation damage dependent grain boundary diffusion is observed at 1300 °C in CVD-SiC. The results seem to indicate, that the chemically inert noble gas atoms do not form defect-impurity complexes, which strongly influence the diffusion behavior of other diffusors in silicon carbide.

  17. Radial diffusion of radiation belt particles in nondipolar magnetic fields

    NASA Astrophysics Data System (ADS)

    Cunningham, Gregory S.

    2016-06-01

    The fact that charged particles trapped in Earth's magnetic field can be redistributed along their radial distance from Earth due to drift-resonant interactions with small-amplitude waves has been known since early in the space age. Early theoretical efforts assumed that a dipole background magnetic field was modified by a time-varying electromagnetic perturbation that changed the particle's distance from Earth while preserving the first two invariants of motion. The stochastic nature of the perturbation allowed the effect of the waves on the trapped particles to be represented by a Fokker-Planck equation, which updates the phase space density in time via radial diffusion with diffusion coefficients that depend on the wave characteristics. In this paper, we extend those early theoretical efforts to define radial diffusion coefficients in arbitrary static background fields and define a numerical scheme for their evaluation. The background fields we consider are allowed to have significant deviations from a dipole field. Radial diffusion coefficients are computed using the new scheme for one of the empirical magnetic field models (T89) developed by Tsyganenko and coauthors as the background on top of which the perturbations are added. The new diffusion coefficients are shown to be substantially larger than those computed with a dipole background field model, especially at large radial distances and during geomagnetically active times, and it is suggested that outward radial diffusion may be a more substantial loss process for trapped electrons in the outer radiation belt than previously believed.

  18. DSMC simulation of two-phase plume flow with UV radiation

    NASA Astrophysics Data System (ADS)

    Li, Jie; Liu, Ying; Wang, Ning; Jin, Ling

    2014-12-01

    Rarefied gas-particle two-phase plume in which the phase of particles is liquid or solid flows from a solid propellant rocket of hypersonic vehicle flying at high altitudes, the aluminum oxide particulates not only impact the rarefied gas flow properties, but also make a great difference to plume radiation signature, so the radiation prediction of the rarefied gas-particle two-phase plume flow is very important for space target detection of hypersonic vehicles. Accordingly, this project aims to study the rarefied gas-particle two-phase flow and ultraviolet radiation (UV) characteristics. Considering a two-way interphase coupling of momentum and energy, the direct simulation Monte Carlo (DSMC) method is developed for particle phase change and the particle flow, including particulate collision, coalescence as well as separation, and a Monte Carlo ray trace model is implemented for the particulate UV radiation. A program for the numerical simulation of the gas-particle two-phase flow and radiation in which the gas flow nonequilibrium is strong is implemented as well. Ultraviolet radiation characteristics of the particle phase is studied based on the calculation of the flow field coupled with the radiation calculation, the radiation model for different size particles is analyzed, focusing on the effects of particle emission, absorption, scattering as well as the searchlight emission of the nozzle. A new approach may be proposed to describe the rarefied gas-particle two-phase plume flow and radiation transfer characteristics in this project.

  19. DSMC simulation of two-phase plume flow with UV radiation

    SciTech Connect

    Li, Jie; Liu, Ying; Wang, Ning; Jin, Ling

    2014-12-09

    Rarefied gas-particle two-phase plume in which the phase of particles is liquid or solid flows from a solid propellant rocket of hypersonic vehicle flying at high altitudes, the aluminum oxide particulates not only impact the rarefied gas flow properties, but also make a great difference to plume radiation signature, so the radiation prediction of the rarefied gas-particle two-phase plume flow is very important for space target detection of hypersonic vehicles. Accordingly, this project aims to study the rarefied gas-particle two-phase flow and ultraviolet radiation (UV) characteristics. Considering a two-way interphase coupling of momentum and energy, the direct simulation Monte Carlo (DSMC) method is developed for particle phase change and the particle flow, including particulate collision, coalescence as well as separation, and a Monte Carlo ray trace model is implemented for the particulate UV radiation. A program for the numerical simulation of the gas-particle two-phase flow and radiation in which the gas flow nonequilibrium is strong is implemented as well. Ultraviolet radiation characteristics of the particle phase is studied based on the calculation of the flow field coupled with the radiation calculation, the radiation model for different size particles is analyzed, focusing on the effects of particle emission, absorption, scattering as well as the searchlight emission of the nozzle. A new approach may be proposed to describe the rarefied gas-particle two-phase plume flow and radiation transfer characteristics in this project.

  20. WHAT ARE THE EFFECTS OF UV-B RADIATION ON MARINE ORGANISMS

    EPA Science Inventory

    As early as 1925, scientists were aware of damaging effects on aquatic organisms from the ultraviolet component of sunlight. It was shown at these early dates that there exists a differential sensitivity among species to UV radiation, and that this differential sensitivity might ...

  1. AMBIENT SOLAR UV RADIATION CAUSES MORTALITY IN LARVAE OF THREE SPECIES OF RANA

    EPA Science Inventory

    Recent reports concerning the lethal effects of solar ultraviolet-B (UV-B) radiation on amphibians suggest that this stressor has the potential to impact some amphibian populations. In this study embryos and larvae of three anuran species, Rana pipiens, R. clamitans, and R. septe...

  2. INHIBITION OF PS II PHOTOCHEMISTRY BY PAR AND UV RADIATION IN NATURAL PHYTOPLANKTON COMMUNITIES

    EPA Science Inventory

    The effects of PAR and UV radiation on PS II photochemistry were examined in natural phytoplankton communities from coastal waters off Rhode Island (USA) and the subtropical Pacific. he photochemical energy conversion efficiency, the functional absorption cross section and the ki...

  3. Photocatalytic ROS production and phototoxicity of titanium dioxide nanoparticles is dependent on solar UV radiation spectrum

    EPA Science Inventory

    Generation of reactive oxygen species (ROS) by titanium dioxide nanoparticles (nano-TiO2) and its consequent phototoxicity to Daphnia magna were measured under different solar UV radiation spectrum by applying a series of optical filters in a solar simulator. Removing UVB (280-32...

  4. Effects of solar UV radiation on alkaloid production in Erythroxylum novogranatense var. novogranatense

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cocaine-producing species of Erythroxylum have been cultivated in South America for centuries, yet little is know of environmental effects on alkaloid production in these species. Given the high incidence of UV radiation in the equatorial and high altitude environments in which cocaine-producing sp...

  5. INTRASPECIFIC VARIATION IN SENSITIVITY TO UV-B RADIATION IN RICE

    EPA Science Inventory

    Twenty-two cultivars of rice (Oryza sativa L.) from diverse origins were grown under greenhouse conditions and exposed to ultraviolet-B radiation (UV-B; 280-320 nm) simulating a 5% reduction in stratospheric ozone in spring for the Philippines (14 degrees N lat.) to evaluate grow...

  6. Evaluation of UV-permeability and photo-oxidisability of organic ultraviolet radiation-absorbing coatings

    NASA Astrophysics Data System (ADS)

    Li, Neng; Chen, Yuhe; Bao, Yongjie; Zhang, Zeqian; Wu, Zaixing; Chen, Zhangmin

    2015-03-01

    Enhancing the durability of the coatings used on bamboo products is essential for increasing their use in outdoor environments. In this study, we investigated organic UV radiation-absorbing coatings for use on bamboo surfaces. The degree of resistance of the coatings, which contained 2-(2-hydroxy-3-tert-butyl-5-methyl-phenyl)-5-chlorinated benzotriazole (BTZ-1), to UV radiation degradation was determined through spectroscopic analysis. The critical BTZ-1 loading amount was determined by analysing the spectroscopic data. Fourier transform infrared spectroscopy was used to elucidate the relationship between the degree of photooxidation of the coatings and their BTZ-1 concentration. The experimental results showed that the coatings provided a high degree of shielding from UV radiation. The critical loading amount was determined to be 1.82 ± 0.05 g BTZ-1/m2. The coatings formed using the formulations that contained 3 and 5 wt% BTZ-1 exhibited the lowest degree of photooxidation after exposure to UV radiation.

  7. GROWTH RESPONSE OF SYMBODINIUM SPP. TO COMBINED TEMPERATURE AND UV RADIATION

    EPA Science Inventory

    Rogers, J.E. and D. Marcovich. In press. Growth Response of a Coral Symbiont, Symbiodinium sp., to Combined Temperature and UV Radiation Exposure (Abstract). To be presented at the ASLO 2004 Summer Meeting: The Changing Landscapes of Oceans and Freshwater, 13-18 June 2004, Savann...

  8. ATTENUATION OF SOLAR UV RADIATION BY AEROSOLS DURING AIR POLLUTION EPISODES

    EPA Science Inventory

    Increase in the amount of solar UV radiation reaching the surface due to decrease in stratospheric ozone continues to be a major concern (WMO, 1998). However, recent studies show that absorption and smattering by aerosols during air pollution episode decreases the amount of radi...

  9. The effect of UV radiation on survival of Salmonella enterica in dried manure dust

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Animal manure has been shown to harbor Salmonella enterica, an enteric pathogen known to be resilient to environmental stresses such as desiccation and solar UV radiation. In farm settings, it has been observed that unintended aerosolization could occur when manure becomes dehydrated, ...

  10. UV-B absorbing compounds in present-day and fossil pollen, spores, cuticles, seed coats and wood: evaluation of a proxy for solar UV radiation.

    PubMed

    Rozema, J; Blokker, P; Mayoral Fuertes, M A; Broekman, R

    2009-09-01

    UV-B absorbing compounds (UACs) in present-day and fossil pollen, spores, cuticles, seed coats and wood have been evaluated as a proxy for past UV. This proxy may not only provide information on variation of stratospheric ozone and solar UV in the period preceding and during the Antarctic ozone hole (1974-present day), but also on the development and variation of the stratospheric ozone layer and solar surface UV during the evolution of life on Earth. Sporopollenin and cutin are highly resistant biopolymers, preserving well in the geological record and contain the phenolic acids p-coumaric (pCA) and ferulic acid (FA). pCA and FA represent a good perspective for a plant-based proxy for past surface UV radiation since they are induced by solar UV-B via the phenylpropanoid pathway (PPP). UV-B absorption by these monomers in the wall of pollen and spores and in cuticles may prevent damage to the cellular metabolism. Increased pCA and FA in pollen of Vicia faba exposed to enhanced UV-B was found in greenhouse experiments. Further correlative evidence comes from UV-absorbing compounds in spores from 1960-2000 comparing exposure of land plants (Lycopodium species) to solar UV before and during ozone depletion and comparing plants from Antarctica (severe ozone depletion), Arctic, and other latitudes with less or negligible ozone depletion. Wood-derived compounds guaiacyl (G), syringyl (S), and p-hydroxyphenyl (P) are produced via the PPP. The proportions of P, G, and S in the lignin differ between various plant groups (e.g. dicotyledons/monocotyledons, gymnosperms/angiosperms). It is hypothesized that this lignin composition and derived physiological and physical properties of lignin (such as tree-ring wood density) has potential as a proxy for palaeo-UV climate. However validation by exposure of trees to enhanced UV is lacking. pCA and FA also form part of cutin polymers and are found in extant and fossil Ginkgo leaf cuticles as shown by thermally-assisted hydrolysis and