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Sample records for albeit ultraviolet bright

  1. Extreme Ultraviolet Explorer Bright Source List

    Science.gov (United States)

    Malina, Roger F.; Marshall, Herman L.; Antia, Behram; Christian, Carol A.; Dobson, Carl A.; Finley, David S.; Fruscione, Antonella; Girouard, Forrest R.; Hawkins, Isabel; Jelinsky, Patrick

    1994-01-01

    Initial results from the analysis of the Extreme Ultraviolet Explorer (EUVE) all-sky survey (58-740 A) and deep survey (67-364 A) are presented through the EUVE Bright Source List (BSL). The BSL contains 356 confirmed extreme ultraviolet (EUV) point sources with supporting information, including positions, observed EUV count rates, and the identification of possible optical counterparts. One-hundred twenty-six sources have been detected longward of 200 A.

  2. Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV

    Energy Technology Data Exchange (ETDEWEB)

    Wang, He [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Xu, Yiming [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Ulonska, Stefan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Robinson, Joseph S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Ranitovic, Predrag [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Kaindl, Robert A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division

    2015-06-11

    Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of correspondingly weak driving pulses is challenging. In this article, we demonstrate a highly-efficient source of femtosecond extreme-ultraviolet pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ≈3 × 1013 s-1 is generated at 22.3 eV, with 5 × 10-5 conversion efficiency that surpasses similar harmonics directly driven by the fundamental by two orders-of-magnitude. The enhancement arises from both wavelength scaling of the atomic dipole and improved spatio-temporal phase matching, confirmed by simulations. Finally, spectral isolation of a single 72-meV-wide harmonic renders this bright, 50-kHz extreme-ultraviolet source a powerful tool for ultrafast photoemission, nanoscale imaging and other applications.

  3. YOUNG, ULTRAVIOLET-BRIGHT STARS DOMINATE DUST HEATING IN STAR-FORMING GALAXIES

    International Nuclear Information System (INIS)

    Law, Ka-Hei; Gordon, Karl D.; Misselt, K. A.

    2011-01-01

    In star-forming galaxies, dust plays a significant role in shaping the ultraviolet (UV) through infrared (IR) spectrum. Dust attenuates the radiation from stars, and re-radiates the energy through equilibrium and non-equilibrium emission. Polycyclic aromatic hydrocarbons (PAHs), graphite, and silicates contribute to different features in the spectral energy distribution; however, they are all highly opaque in the same spectral region-the UV. Compared to old stellar populations, young populations release a higher fraction of their total luminosity in the UV, making them a good source of the energetic UV photons that can power dust emission. However, given their relative abundance, the question of whether young or old stellar populations provide most of these photons that power the IR emission is an interesting question. Using three samples of galaxies observed with the Spitzer Space Telescope and our dusty radiative transfer model, we find that young stellar populations (on the order of 100 million years old) dominate the dust heating in star-forming galaxies, and old stellar populations (13 billion years old) generally contribute less than 20% of the far-IR luminosity.

  4. Sparkling extreme-ultraviolet bright dots observed with Hi-C

    International Nuclear Information System (INIS)

    Régnier, S.; Alexander, C. E.; Walsh, R. W.; Winebarger, A. R.; Cirtain, J.; Golub, L.; Korreck, K. E.; Weber, M.; Mitchell, N.; Platt, S.; De Pontieu, B.; Title, A.; Kobayashi, K.; Kuzin, S.; DeForest, C. E.

    2014-01-01

    Observing the Sun at high time and spatial scales is a step toward understanding the finest and fundamental scales of heating events in the solar corona. The high-resolution coronal (Hi-C) instrument has provided the highest spatial and temporal resolution images of the solar corona in the EUV wavelength range to date. Hi-C observed an active region on 2012 July 11 that exhibits several interesting features in the EUV line at 193 Å. One of them is the existence of short, small brightenings 'sparkling' at the edge of the active region; we call these EUV bright dots (EBDs). Individual EBDs have a characteristic duration of 25 s with a characteristic length of 680 km. These brightenings are not fully resolved by the SDO/AIA instrument at the same wavelength; however, they can be identified with respect to the Hi-C location of the EBDs. In addition, EBDs are seen in other chromospheric/coronal channels of SDO/AIA, which suggests a temperature between 0.5 and 1.5 MK. Based on their frequency in the Hi-C time series, we define four different categories of EBDs: single peak, double peak, long duration, and bursty. Based on a potential field extrapolation from an SDO/HMI magnetogram, the EBDs appear at the footpoints of large-scale, trans-equatorial coronal loops. The Hi-C observations provide the first evidence of small-scale EUV heating events at the base of these coronal loops, which have a free magnetic energy of the order of 10 26 erg.

  5. Differential responses to high- and low-dose ultraviolet-B stress in tobacco Bright Yellow-2 cells

    Science.gov (United States)

    Takahashi, Shinya; Kojo, Kei H.; Kutsuna, Natsumaro; Endo, Masaki; Toki, Seiichi; Isoda, Hiroko; Hasezawa, Seiichiro

    2015-01-01

    Ultraviolet (UV)-B irradiation leads to DNA damage, cell cycle arrest, growth inhibition, and cell death. To evaluate the UV-B stress–induced changes in plant cells, we developed a model system based on tobacco Bright Yellow-2 (BY-2) cells. Both low-dose UV-B (low UV-B: 740 J m−2) and high-dose UV-B (high UV-B: 2960 J m−2) inhibited cell proliferation and induced cell death; these effects were more pronounced at high UV-B. Flow cytometry showed cell cycle arrest within 1 day after UV-B irradiation; neither low- nor high-UV-B–irradiated cells entered mitosis within 12 h. Cell cycle progression was gradually restored in low-UV-B–irradiated cells but not in high-UV-B–irradiated cells. UV-A irradiation, which activates cyclobutane pyrimidine dimer (CPD) photolyase, reduced inhibition of cell proliferation by low but not high UV-B and suppressed high-UV-B–induced cell death. UV-B induced CPD formation in a dose-dependent manner. The amounts of CPDs decreased gradually within 3 days in low-UV-B–irradiated cells, but remained elevated after 3 days in high-UV-B–irradiated cells. Low UV-B slightly increased the number of DNA single-strand breaks detected by the comet assay at 1 day after irradiation, and then decreased at 2 and 3 days after irradiation. High UV-B increased DNA fragmentation detected by the terminal deoxynucleotidyl transferase dUTP nick end labeling assay 1 and 3 days after irradiation. Caffeine, an inhibitor of ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3-related (ATR) checkpoint kinases, reduced the rate of cell death in high-UV-B–irradiated cells. Our data suggest that low-UV-B–induced CPDs and/or DNA strand-breaks inhibit DNA replication and proliferation of BY-2 cells, whereas larger contents of high-UV-B–induced CPDs and/or DNA strand-breaks lead to cell death. PMID:25954287

  6. Biotinylation is a natural, albeit rare, modification of human histones

    Science.gov (United States)

    Kuroishi, Toshinobu; Rios-Avila, Luisa; Pestinger, Valerie; Wijeratne, Subhashinee S. K.; Zempleni, Janos

    2011-01-01

    Previous studies suggest that histones H3 and H4 are posttranslationally modified by binding of the vitamin biotin, catalyzed by holocarboxylase synthetase (HCS). Albeit a rare epigenetic mark, biotinylated histones were repeatedly shown to be enriched in repeat regions and repressed loci, participating in the maintenance of genome stability and gene regulation. Recently, a team of investigators failed to detect biotinylated histones and proposed that biotinylation is not a natural modification of histones, but rather an assay artifact. Here, we describe the results of experiments, including the comparison of various analytical protocols, antibodies, cell lines, classes of histones, and radiotracers. These studies provide unambiguous evidence that biotinylation is a natural, albeit rare, histone modification. Less than 0.001% of human histones H3 and H4 are biotinylated, raising concerns that the abundance might too low to elicit biological effects in vivo. We integrated information from this study, previous studies, and ongoing research efforts to present a new working model in which biological effects are caused by a role of HCS in multiprotein complexes in chromatin. In this model, docking of HCS in chromatin causes the occasional binding of biotin to histones as a tracer for HCS binding sites. PMID:21930408

  7. Nuclear power as a necessary option, albeit in insufficient one

    International Nuclear Information System (INIS)

    Altin, V.

    2007-01-01

    In this presentation a comparative assessment of known energy resources are made with respect to their energy densities. Fossil fuels have formed the foundation of a worldwide economic development realized throughout the 20th century. Their comparatively high energy densities have made faster energy flows and thereby higher power levels and speedy development possible. However, renewable sources that are already feasible have much lower levels of energy densities. Their large scale utilization in lieu of fossil fuels would necessitate either reduction of economic growth rates to 'sustainable' levels or speedy development of feasible large scale storage technologies. Nuclear energy appears to impose itself as a necessity to alleviate this transition period, albeit within the constraint of known uranium reserves an insufficient one

  8. First ultraviolet observations of the transition regions of X-ray bright solar-type stars in the Pleiades

    Science.gov (United States)

    Caillault, J.-P.; Vilhu, O.; Linsky, J. L.

    1990-01-01

    Results are reported from A UV study of the transition regions of two X-ray-bright solar-type stars from the Pleiades, in an attempt to extend the main sequence age baseline for the transition-region activity-age relation over more than two orders of magnitude. However, no emission lines were detected from either star; the upper limits to the fluxes are consistent with previously determined saturation levels, but do not help to further constrain evolutionary models.

  9. The ultraviolet to infrared energy distribution of the BL Lacertae object PKS 0422+00 at two different brightness levels

    Energy Technology Data Exchange (ETDEWEB)

    Falomo, R.; Bouchet, P.; Maraschi, L.; Treves, A.; Tanzi, E.G. (Padova, Osservatorio Astronomico, Padua (Italy) European Southern Observatory, La Silla (Chile) Milano Universita, Milan (Italy) CNR, Istituto di Fisica Cosmica, Milan (Italy))

    1989-10-01

    The BL Lacertae object PKS 0422+00 was observed with IUE (International Ultraviolet Explorer) on August 31-September 1, 1987, when the visual magnitude of the object was V = 16.2, and again about 4 months later (January 10, 1988) during an active state (V = 15.6). Quasi-simultaneous optical to infrared observations allow deriving a detailed spectral flux distribution from 8 x 10 to the 13th to 2.5 x 10 the 15th Hz, for each epoch. Fits in terms of broken power laws and logarithmic parabolas are discussed. 32 refs.

  10. The ultraviolet to infrared energy distribution of the BL Lacertae object PKS 0422+00 at two different brightness levels

    International Nuclear Information System (INIS)

    Falomo, R.; Bouchet, P.; Maraschi, L.; Treves, A.; Tanzi, E.G.

    1989-01-01

    The BL Lacertae object PKS 0422+00 was observed with IUE (International Ultraviolet Explorer) on August 31-September 1, 1987, when the visual magnitude of the object was V = 16.2, and again about 4 months later (January 10, 1988) during an active state (V = 15.6). Quasi-simultaneous optical to infrared observations allow deriving a detailed spectral flux distribution from 8 x 10 to the 13th to 2.5 x 10 the 15th Hz, for each epoch. Fits in terms of broken power laws and logarithmic parabolas are discussed. 32 refs

  11. ULTRAVIOLET-BRIGHT STELLAR POPULATIONS AND THEIR EVOLUTIONARY IMPLICATIONS IN THE COLLAPSED-CORE CLUSTER M15

    International Nuclear Information System (INIS)

    Haurberg, Nathalie C.; Lubell, Gabriel M. G.; Cohn, Haldan N.; Lugger, Phyllis M.; Anderson, Jay; Cool, Adrienne M.; Serenelli, Aldo M.

    2010-01-01

    We performed deep photometry of the central region of the Galactic globular cluster M15 from archival Hubble Space Telescope data taken on the High Resolution Channel and Solar Blind Channel of the Advanced Camera for Surveys. Our data set consists of images in far-UV (FUV 140 ; F140LP), near-UV (NUV 220 ; F220W), and blue (B 435 ; F435W) filters. The addition of an optical filter complements previous UV work on M15 by providing an additional constraint on the UV-bright stellar populations. Using color-magnitude diagrams (CMDs), we identified several populations that arise from non-canonical evolution including candidate blue stragglers, extreme horizontal branch (HB) stars, blue hook (BHk) stars, cataclysmic variables (CVs), and helium-core white dwarfs (He WDs). Due to preliminary identification of several He WD and BHk candidates, we add M15 as a cluster containing an He WD sequence and suggest it be included among clusters with a BHk population. We also investigated a subset of CV candidates that appear in the gap between the main sequence (MS) and WDs in FUV 140 -NUV 220 but lie securely on the MS in NUV 220 -B 435 . These stars may represent a magnetic CV or detached WD-MS binary population. Additionally, we analyze our candidate He WDs using model cooling sequences to estimate their masses and ages and investigate the plausibility of thin versus thick hydrogen envelopes. Finally, we identify a class of UV-bright stars that lie between the HB and WD cooling sequences, a location not usually populated on cluster CMDs. We conclude these stars may be young, low-mass He WDs.

  12. Hubble space telescope near-ultraviolet spectroscopy of the bright cemp-no star BD+44°493

    International Nuclear Information System (INIS)

    Placco, Vinicius M.; Beers, Timothy C.; Smith, Verne V.; Roederer, Ian U.; Cowan, John J.; Frebel, Anna; Filler, Dan; Ivans, Inese I.; Lawler, James E.; Schatz, Hendrik; Sneden, Christopher; Sobeck, Jennifer S.; Aoki, Wako

    2014-01-01

    We present an elemental-abundance analysis, in the near-ultraviolet (NUV) spectral range, for the extremely metal-poor star BD+44°493 a ninth magnitude subgiant with [Fe/H] =–3.8 and enhanced carbon, based on data acquired with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. This star is the brightest example of a class of objects that, unlike the great majority of carbon-enhanced metal-poor (CEMP) stars, does not exhibit over-abundances of heavy neutron-capture elements (CEMP-no). In this paper, we validate the abundance determinations for a number of species that were previously studied in the optical region, and obtain strong upper limits for beryllium and boron, as well as for neutron-capture elements from zirconium to platinum, many of which are not accessible from ground-based spectra. The boron upper limit we obtain for BD+44°493, log ε (B) <–0.70, the first such measurement for a CEMP star, is the lowest yet found for very and extremely metal-poor stars. In addition, we obtain even lower upper limits on the abundances of beryllium, log ε (Be) <–2.3, and lead, log ε (Pb) <–0.23 ([Pb/Fe] <+1.90), than those reported by previous analyses in the optical range. Taken together with the previously measured low abundance of lithium, the very low upper limits on Be and B suggest that BD+44°493 was formed at a very early time, and that it could well be a bona-fide second-generation star. Finally, the Pb upper limit strengthens the argument for non-s-process production of the heavy-element abundance patterns in CEMP-no stars.

  13. Accompanying of parameters of color, brightness and hardness on polymeric films coated with pigmented inks cured by different radiation doses of ultraviolet light

    International Nuclear Information System (INIS)

    Bardi, M.A.G.; Machado, L.D.B.

    2011-01-01

    Complete text of publication follows. In the search for alternatives to traditional paint systems containing solvents, the curing process of polymer coatings by ultraviolet (UV) light has been widely studied and discussed, specially because of their high content of solids and null emission of VOCs. Radiation curing is defined as the conversion of a reactive liquid into a solid through polymerization and crosslinking reactions between the species, promoted by the interaction of the chemical system with the incident ionizing radiation. The appearance of the coated object (e.g., color, gloss) is a complex function of the light incident on the object, the optical scattering characteristic of the material, and human perception. Pigments are very fine powders being nearly insoluble in binders and solvents, but provide color and the ability to hide the underlying surface. In this context, this paper aims to investigate variations on color, brightness and hardness of UV-cured pigmented coatings by different doses. When it comes to irradiation exposition, the incorporation of pigments can preferentially cause its reflection or absorption of the incident radiation. Reflection usually occurs at the pigment surface within the resin so that the radiation has to pass through the top layers twice. Some degradation can, therefore, occur at the surface, and this is why materials frequently lose gloss on exposure.

  14. High brightness extreme ultraviolet (at 13.5 nm) emission from time-of-flight controlled discharges with coaxial fuel injection

    International Nuclear Information System (INIS)

    Hosokai, Tomonao; Horioka, Kazuhiko; Hotta, Eiki; Yokoyama, Takuma; Sato, Hiroto; Zhidkov, Alexei

    2008-01-01

    Extreme ultraviolet (EUV) emission from discharge produced plasma with the coaxial injection of fuel vapor (tin and lithium) produced by laser ablation is experimentally studied. Multiple plasma pinches preceding a strong and long recombination radiation of EUV are observed in the first half cycle of a sinusoidal discharge current. Due to the time-of-flight control type of the discharge, the shape of pinch radiation pulses is almost identical. With the coaxial injection of time-of-flight controlled discharges, the highest brightness of EUV emission (maximum extracted energy of 244.3 mJ/2π sr per pulse with the emitter size of ∼1x0.3 mm 2 in full width at half maximum) is provided with efficiency exceeding 2% of deposited energy into the plasma (or 1% of dissipated energy in the discharge) due to a much better matching with the optimal plasma parameters in the recombination regime and a decrease in the off-duty factor. Stability of emitting plasma of the repetitive pinches is essentially improved with use of a second laser pulse

  15. Bright point study

    International Nuclear Information System (INIS)

    Tang, F.; Harvey, K.; Bruner, M.; Kent, B.; Antonucci, E.

    1982-01-01

    Transition region and coronal observations of bright points by instruments aboard the Solar Maximum Mission and high resolution photospheric magnetograph observations on September 11, 1980 are presented. A total of 31 bipolar ephemeral regions were found in the photosphere from birth in 9.3 hours of combined magnetograph observations from three observatories. Two of the three ephemeral regions present in the field of view of the Ultraviolet Spectrometer-Polarimeter were observed in the C IV 1548 line. The unobserved ephemeral region was determined to be the shortest-lived (2.5 hr) and lowest in magnetic flux density (13G) of the three regions. The Flat Crystal Spectrometer observed only low level signals in the O VIII 18.969 A line, which were not statistically significant to be positively identified with any of the 16 ephemeral regions detected in the photosphere. In addition, the data indicate that at any given time there lacked a one-to-one correspondence between observable bright points and photospheric ephemeral regions, while more ephemeral regions were observed than their counterparts in the transition region and the corona

  16. Giant Low Surface Brightness Galaxies

    Science.gov (United States)

    Mishra, Alka; Kantharia, Nimisha G.; Das, Mousumi

    2018-04-01

    In this paper, we present radio observations of the giant low surface brightness (LSB) galaxies made using the Giant Metrewave Radio Telescope (GMRT). LSB galaxies are generally large, dark matter dominated spirals that have low star formation efficiencies and large HI gas disks. Their properties suggest that they are less evolved compared to high surface brightness galaxies. We present GMRT emission maps of LSB galaxies with an optically-identified active nucleus. Using our radio data and archival near-infrared (2MASS) and near-ultraviolet (GALEX) data, we studied morphology and star formation efficiencies in these galaxies. All the galaxies show radio continuum emission mostly associated with the centre of the galaxy.

  17. Burkina Faso - BRIGHT II

    Data.gov (United States)

    Millennium Challenge Corporation — Millennium Challenge Corporation hired Mathematica Policy Research to conduct an independent evaluation of the BRIGHT II program. The three main research questions...

  18. Ultraviolet Extensions

    Science.gov (United States)

    2008-01-01

    [figure removed for brevity, see original site] Side-by-Side Comparison Click on image for larger view This ultraviolet image from NASA's Galaxy Evolution Explorer shows the Southern Pinwheel galaxy, also know as Messier 83 or M83. It is located 15 million light-years away in the southern constellation Hydra. Ultraviolet light traces young populations of stars; in this image, young stars can be seen way beyond the main spiral disk of M83 up to 140,000 light-years from its center. Could life exist around one of these far-flung stars? Scientists say it's unlikely because the outlying regions of a galaxy are lacking in the metals required for planets to form. The image was taken at scheduled intervals between March 15 and May 20, 2007. It is one of the longest-exposure, or deepest, images ever taken of a nearby galaxy in ultraviolet light. Near-ultraviolet light (or longer-wavelength ultraviolet light) is colored yellow, and far-ultraviolet light is blue. What Lies Beyond the Edge of a Galaxy The side-by-side comparison shows the Southern Pinwheel galaxy, or M83, as seen in ultraviolet light (right) and at both ultraviolet and radio wavelengths (left). While the radio data highlight the galaxy's long, octopus-like arms stretching far beyond its main spiral disk (red), the ultraviolet data reveal clusters of baby stars (blue) within the extended arms. The ultraviolet image was taken by NASA's Galaxy Evolution Explorer between March 15 and May 20, 2007, at scheduled intervals. Back in 2005, the telescope first photographed M83 over a shorter period of time. That picture was the first to reveal far-flung baby stars forming up to 63,000 light-years from the edge of the main spiral disk. This came as a surprise to astronomers because a galaxy's outer territory typically lacks high densities of star-forming materials. The newest picture of M83 from the Galaxy Evolution Explorer is shown at the right, and was taken over a longer period of time. In fact, it is one of the

  19. Ultraviolet Imaging Telescope images of the reflection nebula NGC 7023 - Derivation of ultraviolet scattering properties of dust grains

    Science.gov (United States)

    Witt, Adolf N.; Petersohn, Jens K.; Bohlin, Ralph C.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P.

    1992-01-01

    The Ultraviolet Imaging Telescope as part of the Astro-1 mission, was used to obtain high-resolution surface brightness distribution data in six ultraviolet wavelength bands for the bright reflection nebula NGC 7023. From the quantitative comparison of the measured surface brightness gradients ratios of nebular to stellar flux, and detail radial surface brightness profiles with corresponding data from the visible, two major conclusions results: (1) the scattering in the near- and far-ultraviolet in this nebula is more strongly forward-directed than in the visible; (2) the dust albedo in the ultraviolet for wavelengths not less than 140 nm is identical to that in the visible, with the exception of the 220 nm bump in the extinction curve. In the wavelengths region of the bump, the albedo is reduced by 25 to 30 percent in comparison with wavelengths regions both shorter and longer. This lower albedo is expected, if the bump is a pure absorption feature.

  20. BrightFocus Foundation

    Science.gov (United States)

    ... About BrightFocus Foundation Featured Content BrightFocus: Investing in Science to Save Mind and Sight We're here to help. Explore ... recognition is very important. Monday, November 6, 2017 New Diagnosis? Managing a mind and sight disease is a journey. And you’ ...

  1. Ultraviolet sterilization

    International Nuclear Information System (INIS)

    Schenck, G.O.

    1987-01-01

    Artificial ultraviolet radiation sources can supply bactericidal energy in such a high dosage that in less than a second a higher degree of disinfection is accomplished than by sun irradiation in hours. Bacteria, viruses, phages, and organic micropollutants can be degraded by photochemical wet combustion down to and below detection limits of organic carbon. There are no known ultraviolet-resistant microorganisms. There are limitations to ultraviolet treatment which can often be overcome by adequate technical measures. Unlike other water purification processes, ultraviolet irradiation only exterminates living organisms. The radiation must be able to penetrate to the objects of the kill; in a dose large enough to kill, and long enough to kill and prevent new growth. Contrary to filters, ultraviolet flow-through reactors do not restrict free flow significantly. In contrast to distillation, ultraviolet irradiation imposes no phase changes to the water. Used as a sequence in ultrapure water systems, maintenance requirements are virtually nonexistent; because of the absence of dissolved and particulate matter in purified water, mechanical cleaning of the photoreactor chambers is not essential. The process is highly economical; energy consumption is low and supervision minimal. 103 refs., 45 figs., 15 tabs

  2. Stunningly bright optical emission

    Science.gov (United States)

    Heinke, Craig O.

    2017-12-01

    The detection of bright, rapid optical pulsations from pulsar PSR J1023+0038 have provided a surprise for researchers working on neutron stars. This discovery poses more questions than it answers and will spur on future work and instrumentation.

  3. Ultraviolet radiation: the eye

    International Nuclear Information System (INIS)

    Cesarini, J.P.; Sliney, D.H.

    1996-01-01

    Under most conditions, the eye is well adapted to protect itself against ultraviolet radiation encountered in the outdoor environment as a result of the exposure geometry of the sun. Only when snow is on the ground does one experience acute effects of UV sunlight exposure (i.e. snow blindness, or photokeratitis). With regard to artificial sources, there are many occasions where one views bright light sources such as tungsten-halogen lamps, arc lamps and welding arcs. Such viewing is normally only momentary because of the aversion response to bright light and due to discomfort glare. However, such an aversion does not take place for germicidal lamps and other UV lamps which do not contain a strong visible component in their spectrum. The adverse effects from viewing such sources has been studied for decades and during the last two decades guidelines for limiting exposure to protect the eye have been developed. The guidelines were fostered to a large extent by the growing use of lasers and the quickly recognized hazard posed by viewing laser sources. (author)

  4. High Brightness OLED Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Spindler, Jeffrey [OLEDWorks LLC; Kondakova, Marina [OLEDWorks LLC; Boroson, Michael [OLEDWorks LLC; Hamer, John [OLEDWorks LLC

    2016-05-25

    In this work we describe the technology developments behind our current and future generations of high brightness OLED lighting panels. We have developed white and amber OLEDs with excellent performance based on the stacking approach. Current products achieve 40-60 lm/W, while future developments focus on achieving 80 lm/W or higher.

  5. High brightness ion source

    International Nuclear Information System (INIS)

    Dreyfus, R.W.; Hodgson, R.T.

    1975-01-01

    A high brightness ion beam is obtainable by using lasers to excite atoms or molecules from the ground state to an ionized state in increments, rather than in one step. The spectroscopic resonances of the atom or molecule are used so that relatively long wavelength, low power lasers can be used to obtain such ion beam

  6. The brightness of colour.

    Directory of Open Access Journals (Sweden)

    David Corney

    Full Text Available The perception of brightness depends on spatial context: the same stimulus can appear light or dark depending on what surrounds it. A less well-known but equally important contextual phenomenon is that the colour of a stimulus can also alter its brightness. Specifically, stimuli that are more saturated (i.e. purer in colour appear brighter than stimuli that are less saturated at the same luminance. Similarly, stimuli that are red or blue appear brighter than equiluminant yellow and green stimuli. This non-linear relationship between stimulus intensity and brightness, called the Helmholtz-Kohlrausch (HK effect, was first described in the nineteenth century but has never been explained. Here, we take advantage of the relative simplicity of this 'illusion' to explain it and contextual effects more generally, by using a simple Bayesian ideal observer model of the human visual ecology. We also use fMRI brain scans to identify the neural correlates of brightness without changing the spatial context of the stimulus, which has complicated the interpretation of related fMRI studies.Rather than modelling human vision directly, we use a Bayesian ideal observer to model human visual ecology. We show that the HK effect is a result of encoding the non-linear statistical relationship between retinal images and natural scenes that would have been experienced by the human visual system in the past. We further show that the complexity of this relationship is due to the response functions of the cone photoreceptors, which themselves are thought to represent an efficient solution to encoding the statistics of images. Finally, we show that the locus of the response to the relationship between images and scenes lies in the primary visual cortex (V1, if not earlier in the visual system, since the brightness of colours (as opposed to their luminance accords with activity in V1 as measured with fMRI.The data suggest that perceptions of brightness represent a robust

  7. The Bright Universe Cosmology

    International Nuclear Information System (INIS)

    Surdin, M.

    1980-01-01

    It is shown that viewed from the 'outside', our universe is a black hole. Hence the 'inside' cosmology considered is termed as the Bright Universe Cosmology. The model proposed avoids the singularities of cosmologies of the Big Bang variety, it gives a good account of the redshifts, the cosmic background radiation, the number counts; it also gives a satisfactory explanation of the 'large numbers coincidence' and of the variation in time of fundamental constants. (Auth.)

  8. Solar ultraviolet hazards

    International Nuclear Information System (INIS)

    Azmah Ali

    1995-01-01

    The paper discussed the following subjects: the sources of ultraviolet radiation, solar ultraviolet radiation definition, effects of over exposure to solar ultraviolet radiation, exposure limits and radiation protection of this radiation

  9. Kiloamp high-brightness beams

    International Nuclear Information System (INIS)

    Caporaso, G.J.

    1987-01-01

    Brightness preservation of high-current relativistic electron beams under two different types of transport is discussed. Recent progress in improving the brightness of laser-guided beams in the Advanced Test Accelerator is reviewed. A strategy for the preservation of the brightness of space-charge-dominated beams in a solenoidal transport system is presented

  10. Ultraviolet radiation

    International Nuclear Information System (INIS)

    Hawk, J.

    1986-01-01

    Ultraviolet radiation (UVR) from the sun or artificial sources is reflected or transmitted at the surface of the skin, about 5% of normally incident rays being directly reflected. The transmitted fraction is scattered, photochemically absorbed or dissipated as heat within the skin, or passes from it to contribute to the variable total amount of reflected and transmitted radiation. The UVR absorbers in skin are not definitely known, but DNA is a definite target and probably lipoprotein membranes, RNA, proteins, mucopolysaccharides, elastin and collagen. Photochemical or free radical damage to absorber or nearby organelles leads to pharmacological, ultrastructural, histological and clinical changes. Most frequent DNA damage is pyrimidine dimer formation, apparently inhibiting cell function and replication. This is largely enzymatically repaired in man in the dark by excision repair, post-replication repair and possible other enzymatic mechanisms, and at least in some organisms by light-induced photoreactivation repair. UVR exposure causes well recognized acute and chronic clinical syndromes in man. These are discussed in this paper

  11. Albeit nocturnal, rats subjected to traumatic brain injury do not differ in neurobehavioral performance whether tested during the day or night.

    Science.gov (United States)

    Niesman, Peter J; Wei, Jiahui; LaPorte, Megan J; Carlson, Lauren J; Nassau, Kileigh L; Bao, Gina C; Cheng, Jeffrey P; de la Tremblaye, Patricia; Lajud, Naima; Bondi, Corina O; Kline, Anthony E

    2018-02-05

    Behavioral assessments in rats are overwhelmingly conducted during the day, albeit that is when they are least active. This incongruity may preclude optimal performance. Hence, the goal of this study was to determine if differences in neurobehavior exist in traumatic brain injured (TBI) rats when assessed during the day vs. night. The hypothesis was that the night group would perform better than the day group on all behavioral tasks. Anesthetized adult male rats received either a cortical impact or sham injury and then were randomly assigned to either Day (1:00-3:00p.m.) or Night (7:30-9:30p.m.) testing. Motor function (beam-balance/walk) was conducted on post-operative days 1-5 and cognitive performance (spatial learning) was assessed on days 14-18. Corticosterone (CORT) levels were quantified at 24h and 21days after TBI. No significant differences were revealed between the TBI rats tested during the Day vs. Night for motor or cognition (p'sNight-tested TBI and sham groups at 24h (pday 21 (p>0.05), suggesting an initial, but transient, stress response that did not affect neurobehavioral outcome. These data suggest that the time rats are tested has no noticeable impact on their performance, which does not support the hypothesis. The finding validates the interpretations from numerous studies conducted when rats were tested during the day vs. their natural active period. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. High brightness electron accelerator

    International Nuclear Information System (INIS)

    Sheffield, R.L.; Carlsten, B.E.; Young, L.M.

    1994-01-01

    A compact high brightness linear accelerator is provided for use, e.g., in a free electron laser. The accelerator has a first plurality of accelerating cavities having end walls with four coupling slots for accelerating electrons to high velocities in the absence of quadrupole fields. A second plurality of cavities receives the high velocity electrons for further acceleration, where each of the second cavities has end walls with two coupling slots for acceleration in the absence of dipole fields. The accelerator also includes a first cavity with an extended length to provide for phase matching the electron beam along the accelerating cavities. A solenoid is provided about the photocathode that emits the electrons, where the solenoid is configured to provide a substantially uniform magnetic field over the photocathode surface to minimize emittance of the electrons as the electrons enter the first cavity. 5 figs

  13. Bright point study. [of solar corona

    Science.gov (United States)

    Tang, F.; Harvey, K.; Bruner, M.; Kent, B.; Antonucci, E.

    1982-01-01

    Transition region and coronal observations of bright points by instruments aboard the Solar Maximum Mission and high resolution photospheric magnetograph observations on September 11, 1980 are presented. A total of 31 bipolar ephemeral regions were found in the photosphere from birth in 9.3 hours of combined magnetograph observations from three observatories. Two of the three ephemeral regions present in the field of view of the Ultraviolet Spectrometer-Polarimeter were observed in the C IV 1548 line. The unobserved ephemeral region was determined to be the shortest-lived (2.5 hr) and lowest in magnetic flux density (13G) of the three regions. The Flat Crystal Spectrometer observed only low level signals in the O VIII 18.969 A line, which were not statistically significant to be positively identified with any of the 16 ephemeral regions detected in the photosphere. In addition, the data indicate that at any given time there lacked a one-to-one correspondence between observable bright points and photospheric ephemeral regions, while more ephemeral regions were observed than their counterparts in the transition region and the corona.

  14. Galactic Astronomy in the Ultraviolet

    Science.gov (United States)

    Rastorguev, A. S.; Sachkov, M. E.; Zabolotskikh, M. V.

    2017-12-01

    We propose a number of prospective observational programs for the ultraviolet space observatory WSO-UV, which seem to be of great importance to modern galactic astronomy. The programs include the search for binary Cepheids; the search and detailed photometric study and the analysis of radial distribution of UV-bright stars in globular clusters ("blue stragglers", blue horizontal-branch stars, RR Lyrae variables, white dwarfs, and stars with UV excesses); the investigation of stellar content and kinematics of young open clusters and associations; the study of spectral energy distribution in hot stars, including calculation of the extinction curves in the UV, optical and NIR; and accurate definition of the relations between the UV-colors and effective temperature. The high angular resolution of the observatory allows accurate astrometric measurements of stellar proper motions and their kinematic analysis.

  15. The ZTF Bright Transient Survey

    Science.gov (United States)

    Fremling, C.; Sharma, Y.; Kulkarni, S. R.; Miller, A. A.; Taggart, K.; Perley, D. A.; Gooba, A.

    2018-06-01

    As a supplement to the Zwicky Transient Facility (ZTF; ATel #11266) public alerts (ATel #11685) we plan to report (following ATel #11615) bright probable supernovae identified in the raw alert stream from the ZTF Northern Sky Survey ("Celestial Cinematography"; see Bellm & Kulkarni, 2017, Nature Astronomy 1, 71) to the Transient Name Server (https://wis-tns.weizmann.ac.il) on a daily basis; the ZTF Bright Transient Survey (BTS; see Kulkarni et al., 2018; arXiv:1710.04223).

  16. The ASAS-SN bright supernova catalogue - III. 2016

    Science.gov (United States)

    Holoien, T. W.-S.; Brown, J. S.; Stanek, K. Z.; Kochanek, C. S.; Shappee, B. J.; Prieto, J. L.; Dong, Subo; Brimacombe, J.; Bishop, D. W.; Bose, S.; Beacom, J. F.; Bersier, D.; Chen, Ping; Chomiuk, L.; Falco, E.; Godoy-Rivera, D.; Morrell, N.; Pojmanski, G.; Shields, J. V.; Strader, J.; Stritzinger, M. D.; Thompson, Todd A.; Woźniak, P. R.; Bock, G.; Cacella, P.; Conseil, E.; Cruz, I.; Fernandez, J. M.; Kiyota, S.; Koff, R. A.; Krannich, G.; Marples, P.; Masi, G.; Monard, L. A. G.; Nicholls, B.; Nicolas, J.; Post, R. S.; Stone, G.; Wiethoff, W. S.

    2017-11-01

    This catalogue summarizes information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) and all other bright (mpeak ≤ 17), spectroscopically confirmed supernovae discovered in 2016. We then gather the near-infrared through ultraviolet magnitudes of all host galaxies and the offsets of the supernovae from the centres of their hosts from public data bases. We illustrate the results using a sample that now totals 668 supernovae discovered since 2014 May 1, including the supernovae from our previous catalogues, with type distributions closely matching those of the ideal magnitude limited sample from Li et al. This is the third of a series of yearly papers on bright supernovae and their hosts from the ASAS-SN team.

  17. Teradiode's high brightness semiconductor lasers

    Science.gov (United States)

    Huang, Robin K.; Chann, Bien; Burgess, James; Lochman, Bryan; Zhou, Wang; Cruz, Mike; Cook, Rob; Dugmore, Dan; Shattuck, Jeff; Tayebati, Parviz

    2016-03-01

    TeraDiode is manufacturing multi-kW-class ultra-high brightness fiber-coupled direct diode lasers for industrial applications. A fiber-coupled direct diode laser with a power level of 4,680 W from a 100 μm core diameter, BPP) of 3.5 mm-mrad and is the lowest BPP multi-kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 4-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers. We have also demonstrated novel high peak power lasers and high brightness Mid-Infrared Lasers.

  18. Ultraviolet spectrophotometry from Gemini 11 of stars in Orion

    International Nuclear Information System (INIS)

    Morgan, T.H.; Spear, G.G.; Kondo, Y.; Henize, K.G.

    1975-01-01

    Ultraviolet spectrophotometry in the wavelength region 2600--3600 A is reported for the bright early-type stars β, eta, γ, delta, iota, epsilon, sigma, xi, and kappa Ori. The results are in good agreement with other observations, and with the possible exception of the supergiants, are in good agreement with recent line-blanketed model atmospheres. There is evidence that the supergiants possess a small ultraviolet deficiency shortward of 3000 A relative to main-sequence stars of similar spectral type. The most extreme example of this phenomenon is the star kappa Ori

  19. Unveiling the Low Surface Brightness Stellar Peripheries of Galaxies

    Science.gov (United States)

    Ferguson, Annette M. N.

    2018-01-01

    The low surface brightness peripheral regions of galaxies contain a gold mine of information about how minor mergers and accretions have influenced their evolution over cosmic time. Enormous stellar envelopes and copious amounts of faint tidal debris are natural outcomes of the hierarchical assembly process and the search for and study of these features, albeit highly challenging, offers the potential for unrivalled insight into the mechanisms of galaxy growth. Over the last two decades, there has been burgeoning interest in probing galaxy outskirts using resolved stellar populations. Wide-field surveys have uncovered vast tidal debris features and new populations of very remote globular clusters, while deep Hubble Space Telescope photometry has provided exquisite star formation histories back to the earliest epochs. I will highlight some recent results from studies within and beyond the Local Group and conclude by briefly discussing the great potential of future facilities, such as JWST, Euclid, LSST and WFIRST, for major breakthroughs in low surface brightness galaxy periphery science.

  20. The Ultraviolet Albedo of Ganymede

    Science.gov (United States)

    McGrath, Melissa; Hendrix, A.

    2013-10-01

    A large set of ultraviolet images of Ganymede have been acquired with the Hubble Space Telescope over the last 15 years. These images have been used almost exclusively to study Ganymede’s stunning auroral emissions (Feldman et al. 2000; Eviatar et al. 2001; McGrath et al. 2004; Saur et al. 2011; McGrath et al. 2013), and even the most basic information about Ganymede’s UV albedo has yet to be gleaned from these data. We will present a first-cut analysis of both disk-averaged and spatially-resolved UV albedos of Ganymede, with focus on the spatially-resolved Lyman-alpha albedo, which has never been considered previously for this satellite. Ganymede's visibly bright regions are known to be rich in water ice, while the visibly dark regions seem to be more carbonaceous (Carlson et al., 1996). At Lyman-alpha, these two species should also have very different albedo values. References Carlson, R. and 39 co-authors, Near-infrared spectroscopy and spectral mapping of Jupiter and the Galilean satellites: Results from Galileo’s initial orbit, Science, 274, 385-388, 1996. Eviatar, A., D. F. Strobel, B. C. Wolven, P. D. Feldman, M. A. McGrath, and D. J. Williams, Excitation of the Ganymede ultraviolet aurora, Astrophys. J, 555, 1013-1019, 2001. Feldman, P. D., M. A. McGrath, D. F. Strobel, H. W. Moos, K. D. Retherford, and B. C. Wolven, HST/STIS imaging of ultraviolet aurora on Ganymede, Astrophys. J, 535, 1085-1090, 2000. McGrath M. A., Lellouch E., Strobel D. F., Feldman P. D., Johnson R. E., Satellite Atmospheres, Chapter 19 in Jupiter: The Planet, Satellites and Magnetosphere, ed. F. Bagenal, T. Dowling, W. McKinnon, Cambridge University Press, 2004. McGrath M. A., Jia, Xianzhe; Retherford, Kurt; Feldman, Paul D.; Strobel, Darrell F.; Saur, Joachim, Aurora on Ganymede, J. Geophys. Res., doi: 10.1002/jgra.50122, 2013. Saur, J., S. Duling, S., L. Roth, P. D. Feldman, D. F. Strobel, K. D. Retherford, M. A. McGrath, A. Wennmacher, American Geophysical Union, Fall Meeting

  1. Photodetector of ultraviolet radiation

    International Nuclear Information System (INIS)

    Dorogan, V.; Branzari, V.; Vieru, T.; Manole, M.; Canter, V.

    2000-01-01

    The invention relates to photodetectors on base of semiconductors of ultraviolet radiation and may be used in optoelectronic system for determining the intensity and the dose of ultraviolet radiation emitted by the Sun or other sources. Summary of the invention consists in the fact that in the photodetector of ultraviolet radiation the superficial potential barrier is divided into two identical elements, electrically isolated each of the other, one of them being covered with a layer of transparent material for visible and infrared radiation and absorption the ultra violet radiation. The technical result consists in mutual compensation of visible and infrared components of the radiation spectrum

  2. Helmholtz bright and boundary solitons

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J M [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); McDonald, G S [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); Chamorro-Posada, P [Departmento de TeorIa de la Senal y Comunicaciones e IngenierIa Telematica, Universidad de Valladolid, ETSI Telecomunicacion, Campus Miguel Delibes s/n, 47011 Valladolid (Spain)

    2007-02-16

    We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic nonlinear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently derived Helmholtz bright solitons, for this type of polynomial nonlinearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterparts.

  3. A New Sky Brightness Monitor

    Science.gov (United States)

    Crawford, David L.; McKenna, D.

    2006-12-01

    A good estimate of sky brightness and its variations throughout the night, the months, and even the years is an essential bit of knowledge both for good observing and especially as a tool in efforts to minimize sky brightness through local action. Hence a stable and accurate monitor can be a valuable and necessary tool. We have developed such a monitor, with the financial help of Vatican Observatory and Walker Management. The device is now undergoing its Beta test in preparation for production. It is simple, accurate, well calibrated, and automatic, sending its data directly to IDA over the internet via E-mail . Approximately 50 such monitors will be ready soon for deployment worldwide including most major observatories. Those interested in having one should enquire of IDA about details.

  4. High-brightness injector modeling

    International Nuclear Information System (INIS)

    Lewellen, J.W.

    2004-01-01

    There are many aspects to the successful conception, design, fabrication, and operation of high-brightness electron beam sources. Accurate and efficient modeling of the injector are critical to all phases of the process, from evaluating initial ideas to successful diagnosis of problems during routine operation. The basic modeling tasks will vary from design to design, according to the basic nature of the injector (dc, rf, hybrid, etc.), the type of cathode used (thermionic, photo, field emitter, etc.), and 'macro' factors such as average beam current and duty factor, as well as the usual list of desired beam properties. The injector designer must be at least aware of, if not proficient at addressing, the multitude of issues that arise from these considerations; and, as high-brightness injectors continue to move out of the laboratory, the number of such issues will continue to expand.

  5. Helmholtz bright and boundary solitons

    International Nuclear Information System (INIS)

    Christian, J M; McDonald, G S; Chamorro-Posada, P

    2007-01-01

    We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic nonlinear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently derived Helmholtz bright solitons, for this type of polynomial nonlinearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterparts

  6. Ultraviolet photometry from the Orbiting Astronomical Observatory. XXXII - An atlas of ultraviolet stellar spectra

    Science.gov (United States)

    Code, A. D.; Meade, M. R.

    1979-01-01

    Ultraviolet stellar fluxes are presented in graphs and tables for 164 bright stars in the spectral region from 1200 to 3600 A. The spectra represent a subset of OAO 2 spectrometer data on file at the National Space Science Data Center. The monochromatic flux is given in units of erg per (sq cm-s-A) with a spectral resolution of about 22 A in the region from 3600 to 1850 A and of approximately 12 A in the region from 1850 to 1160 A.

  7. High brightness semiconductor lasers with reduced filamentation

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.

    1999-01-01

    High brightness semiconductor lasers have applications in spectroscopy, fiber lasers, manufacturing and materials processing, medicine and free space communication or energy transfer. The main difficulty associated with high brightness is that, because of COD, high power requires a large aperture...

  8. THE ULTRAVIOLET BRIGHTEST TYPE Ia SUPERNOVA 2011de

    International Nuclear Information System (INIS)

    Brown, Peter J.

    2014-01-01

    We present and discuss the ultraviolet (UV)/optical photometric light curves and absolute magnitudes of the Type Ia supernova (SN Ia) 2011de from the Swift Ultraviolet/Optical Telescope. We find it to be the UV brightest SN Ia yet observed—more than a factor of 10 brighter than normal SNe Ia in the mid-ultraviolet. We find that the UV/optical brightness and broad light curve evolution can be modeled with additional flux from the shock of the ejecta hitting a relatively large red giant companion separated by 6 × 10 13 cm. However, the post-maximum behavior of other UV-bright SNe Ia can also be modeled in a similar manner, including objects with UV spectroscopy or pre-maximum photometry which is inconsistent with this model. This suggests that similar UV luminosities can be intrinsic or caused by other forms of shock interaction. The high velocities reported for SN 2011de make it distinct from the UV-bright ''super-Chandrasekhar'' SNe Ia and the NUV-blue group of normal SNe Ia. SN 2011de is an extreme example of the UV variations in SNe Ia

  9. Electron beam brightness with field immersed emission

    International Nuclear Information System (INIS)

    Boyd, J.K.; Neil, V.K.

    1985-01-01

    The beam quality or brightness of an electron beam produced with field immersed emission is studied with two models. First, an envelope formulation is used to determine the scaling of brightness with current, magnetic field and cathode radius, and examine the equilibrium beam radius. Second, the DPC computer code is used to calculate the brightness of two electron beam sources

  10. Does low surface brightness mean low density?

    NARCIS (Netherlands)

    deBlok, WJG; McGaugh, SS

    1996-01-01

    We compare the dynamical properties of two galaxies at identical positions on the Tully-Fisher relation, but with different surface brightnesses. We find that the low surface brightness galaxy UGC 128 has a higher mass-to-light ratio, and yet has lower mass densities than the high surface brightness

  11. High-brightness rf linear accelerators

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1986-01-01

    The issue of high brightness and its ramifications in linacs driven by radio-frequency fields is discussed. A history of the RF linacs is reviewed briefly. Some current applications are then examined that are driving progress in RF linacs. The physics affecting the brightness of RF linacs is then discussed, followed by the economic feasibility of higher brightness machines

  12. Low surface brightness spiral galaxies

    International Nuclear Information System (INIS)

    Romanishin, W.

    1980-01-01

    This dissertation presents an observational overview of a sample of low surface brightness (LSB) spiral galaxies. The sample galaxies were chosen to have low surface brightness disks and indications of spiral structure visible on the Palomar Sky Survey. They are of sufficient angular size (diameter > 2.5 arcmin), to allow detailed surface photometry using Mayall 4-m prime focus plates. The major findings of this dissertation are: (1) The average disk central surface brightness of the LSB galaxies is 22.88 magnitude/arcsec 2 in the B passband. (2) From broadband color measurements of the old stellar population, we infer a low average stellar metallicity, on the order of 1/5 solar. (3) The spectra and optical colors of the HII regions in the LSB galaxies indicate a lack of hot ionizing stars compared to HII regions in other late-type galaxies. (4) The average surface mass density, measured within the radius containing half the total mass, is less than half that of a sample of normal late-type spirals. (5) The average LSB galaxy neutral hydrogen mass to blue luminosity ratio is about 0.6, significantly higher than in a sample of normal late-type galaxies. (6) We find no conclusive evidence of an abnormal mass-to-light ratio in the LSB galaxies. (7) Some of the LSB galaxies exhibit well-developed density wave patterns. (8) A very crude calculation shows the lower metallicity of the LSB galaxies compared with normal late-type spirals might be explained simply by the deficiency of massive stars in the LSB galaxies

  13. High brightness beams and applications

    International Nuclear Information System (INIS)

    Sheffield, R.L.

    1995-01-01

    This paper describes the present research on attaining intense bright electron beams. Thermionic systems are briefly covered. Recent and past results from the photoinjector programs are given. The performance advantages and difficulties presently faced by researchers using photoinjectors is discussed. The progress that has been made in photocathode materials, both in lifetime and quantum efficiency, is covered. Finally, a discussion of emittance measurements of photoinjector systems and how the measurement is complicated by the non-thermal nature of the electron beam is presented

  14. High-brightness electron injectors

    International Nuclear Information System (INIS)

    Sheffield, R.L.

    1987-01-01

    Free-electron laser (FEL) oscillators and synchrotron light sources require pulse trains of high peak brightness and, in some applications, high-average power. Recent developments in the technology of photoemissive and thermionic electron sources in rf cavities for electron-linac injector applications offer promising advances over conventional electron injectors. Reduced emittance growth in high peak-current electron injectors may be achieved by using high field strengths and by linearizing the radial component of the cavity electric field at the expense of lower shunt impedance

  15. Orientation of coronal bright points and small-scale magnetic bipoles

    International Nuclear Information System (INIS)

    MINENKO, E.P.; SHERDANOV, CH.T.; SATTAROV, I.; KARACHIK, N.V.

    2014-01-01

    Using the observations from Extreme-Ultraviolet Imaging Telescope (EIT) on the SOHO board and longitudinal full-disk magnetograms (vector spectromagnetograph - VSM) from the Synoptic Optical Long-Term Investigations of the Sun (SOLIS), we explore the orientation and relationship between the coronal bright points at 195 A o (hereafter CBPs) and magnetic bipoles (only for the central zone of solar disk). The magnetic bipoles are identified as a pair of streams of positive and negative polarities with a shortest distance between them. This paper presents a study of the structure and orientation (angles) of magnetic bipoles to the solar equator and two types of CBPs: 'dim' CBPs in the quiet regions of the Sun and 'bright' CBPs associated with active regions. For these magnetic bipoles associated with 'bright' CBPs, we find that their orientation angles are distributed randomly along the equator. (authors)

  16. ASASSN-15LH: A SUPERLUMINOUS ULTRAVIOLET REBRIGHTENING OBSERVED BY SWIFT AND HUBBLE

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Peter J.; Yang, Yi; Wang, Lifan [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A. and M. University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Cooke, Jeff; Mould, Jeremy [Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn VIC 3122 (Australia); Olaes, Melanie; Quimby, Robert M. [Department of Astronomy, San Diego State University, San Diego, CA 92182 (United States); Baade, Dietrich [European Organisation for Astronomical Research in the Southern Hemisphere (ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching b. München (Germany); Gehrels, Neil [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Hoeflich, Peter [Department of Physics, Florida State University, Tallahassee, FL 32306 (United States); Maund, Justyn [Department of Physics and Astronomy F39 Hicks Building, Hounsfield Road Sheffield, S3 7RH (United Kingdom); Wheeler, J. Craig [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States)

    2016-09-01

    We present and discuss ultraviolet and optical photometry from the Ultraviolet/Optical Telescope, X-ray limits from the X-Ray Telescope on Swift, and imaging polarimetry and ultraviolet/optical spectroscopy with the Hubble Space Telescope , all from observations of ASASSN-15lh. It has been classified as a hydrogen-poor superluminous supernova (SLSN I), making it more luminous than any other supernova observed. ASASSN-15lh is not detected in the X-rays in individual or co-added observations. From the polarimetry we determine that the explosion was only mildly asymmetric. We find the flux of ASASSN-15lh to increase strongly into the ultraviolet, with an ultraviolet luminosity 100 times greater than the hydrogen-rich, ultraviolet-bright SLSN II SN 2008es. We find that objects as bright as ASASSN-15lh are easily detectable beyond redshifts of ∼4 with the single-visit depths planned for the Large Synoptic Survey Telescope. Deep near-infrared surveys could detect such objects past a redshift of ∼20, enabling a probe of the earliest star formation. A late rebrightening—most prominent at shorter wavelengths—is seen about two months after the peak brightness, which is itself as bright as an SLSN. The ultraviolet spectra during the rebrightening are dominated by the continuum without the broad absorption or emission lines seen in SLSNe or tidal disruption events (TDEs) and the early optical spectra of ASASSN-15lh. Our spectra show no strong hydrogen emission, showing only Ly α absorption near the redshift previously found by optical absorption lines of the presumed host. The properties of ASASSN-15lh are extreme when compared to either SLSNe or TDEs.

  17. The lowest surface brightness disc galaxy known

    International Nuclear Information System (INIS)

    Davies, J.I.; Phillipps, S.; Disney, M.J.

    1988-01-01

    The discovery of a galaxy with a prominent bulge and a dominant extremely low surface brightness disc component is reported. The profile of this galaxy is very similar to the recently discovered giant low surface brightness galaxy Malin 1. The disc central surface brightness is found to be ∼ 26.4 Rμ, some 1.5 mag fainter than Malin 1 and thus by far the lowest yet observed. (author)

  18. Increasing the Brightness of Light Sources

    OpenAIRE

    Fu, Ling

    2006-01-01

    In modern illumination systems, compact size and high brightness are important features. Light recycling allows an increase of the spectral radiance (brightness) emitted by a light source for the price of reducing the total radiant power. Light recycling means returning part of the emitted light to the source where part of it will escape absorption. As a result, the output brightness can be increased in a restricted phase space, ...

  19. IRAS surface brightness maps of reflection nebulae in the Pleiades

    Science.gov (United States)

    Castelaz, Michael W.; Werner, M. W.; Sellgren, K.

    1987-01-01

    Surface brightness maps at 12, 25, 60, and 100 microns were made of a 2.5 deg x 2.5 deg area of the reflection nebulae in the Pleiades by coadding IRAS scans of this region. Emission is seen surrounding 17 Tau, 20 Tau, 23 Tau, and 25 Tau in all four bands, coextensive with the visible reflection nebulosity, and extending as far as 30 arcminutes from the illuminating stars. The infrared energy distributions of the nebulae peak in the 100 micron band, but up to 40 percent of the total infrared power lies in the 12 and 25 micron bands. The brightness of the 12 and 25 micron emission and the absence of temperature gradients at these wavelengths are inconsistent with the predictions of equilibrium thermal emission models. The emission at these wavelengths appears to be the result of micron nonequilibrium emission from very small grains, or from molecules consisting of 10-100 carbon atoms, which have been excited by ultraviolet radiation from the illuminating stars.

  20. Ultraviolet radiation and immunosuppression.

    LENUS (Irish Health Repository)

    Murphy, G M

    2009-11-01

    Ultraviolet (UV) radiation is a complete carcinogen. The effects of UV radiation are mediated via direct damage to cellular DNA in the skin and suppression of image surveillance mechanisms. In the context of organ transplantation, addiction of drugs which suppress the immune system add greatly to the carcinogenicity of UV radiation. This review considers the mechanisms of such effects.

  1. Stellar extreme ultraviolet astronomy

    International Nuclear Information System (INIS)

    Cash, W.C. Jr.

    1978-01-01

    The design, calibration, and launch of a rocket-borne imaging telescope for extreme ultraviolet astronomy are described. The telescope, which employed diamond-turned grazing incidence optics and a ranicon detector, was launched November 19, 1976, from the White Sands Missile Range. The telescope performed well and returned data on several potential stellar sources of extreme ultraviolet radiation. Upper limits ten to twenty times more sensitive than previously available were obtained for the extreme ultraviolet flux from the white dwarf Sirius B. These limits fall a factor of seven below the flux predicted for the star and demonstrate that the temperature of Sirius B is not 32,000 K as previously measured, but is below 30,000 K. The new upper limits also rule out the photosphere of the white dwarf as the source of the recently reported soft x-rays from Sirius. Two other white dwarf stars, Feige 24 and G191-B2B, were observed. Upper limits on the flux at 300 A were interpreted as lower limits on the interstellar hydrogen column densities to these stars. The lower limits indicate interstellar hydrogen densitites of greater than .02 cm -3 . Four nearby stars (Sirius, Procyon, Capella, and Mirzam) were observed in a search for intense low temperature coronae or extended chromospheres. No extreme ultraviolet radiation from these stars was detected, and upper limits to their coronal emisson measures are derived

  2. Ultraviolet fire detector

    Science.gov (United States)

    Turnage, J. E.; Linford, R. M. F.; Cornish, S. D.

    1976-01-01

    System is capable of detecting ultraviolet light emitted by match size flame at distance of 10 ft. System is not affected by high energy or particulate radiation and is therefore particularly suited for applications around nuclear plants and X-ray equipment.

  3. Psoriasis and ultraviolet radiation

    International Nuclear Information System (INIS)

    Farber, E.M.; Nall, L.

    1993-01-01

    Prevention and detection screening programs as a public health service in curtailing the ever-increasing incidence of all forms of skin cancer are reviewed. The effect of solar and artificial ultraviolet radiation on the general population and persons with psoriasis is examined. 54 refs

  4. The bright-bright and bright-dark mode coupling-based planar metamaterial for plasmonic EIT-like effect

    Science.gov (United States)

    Yu, Wei; Meng, Hongyun; Chen, Zhangjie; Li, Xianping; Zhang, Xing; Wang, Faqiang; Wei, Zhongchao; Tan, Chunhua; Huang, Xuguang; Li, Shuti

    2018-05-01

    In this paper, we propose a novel planar metamaterial structure for the electromagnetically induced transparency (EIT)-like effect, which consists of a split-ring resonator (SRR) and a pair of metal strips. The simulated results indicate that a single transparency window can be realized in the symmetry situation, which originates from the bright-bright mode coupling. Further, a dual-band EIT-like effect can be achieved in the asymmetry situation, which is due to the bright-bright mode coupling and bright-dark mode coupling, respectively. Different EIT-like effect can be simultaneously achieved in the proposed structure with the different situations. It is of certain significance for the study of EIT-like effect.

  5. Brightness and darkness as perceptual dimensions

    NARCIS (Netherlands)

    Vladusich, T.; Lucassen, M.P.; Cornelissen, F.W.

    2007-01-01

    A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D) space varying from bright to dark. The

  6. SURFACE PHOTOMETRY OF LOW SURFACE BRIGHTNESS GALAXIES

    NARCIS (Netherlands)

    DEBLOK, WJG; VANDERHULST, JM; BOTHUN, GD

    1995-01-01

    Low surface brightness (LSB) galaxies are galaxies dominated by an exponential disc whose central surface brightness is much fainter than the value of mu(B)(0) = 21.65 +/- 0.30 mag arcsec(-2) found by Freeman. In this paper we present broadband photometry of a sample of 21 late-type LSB galaxies.

  7. Variability of the BL Lacertae objects PKS 2155 - 304 and OJ 287 in the far-ultraviolet

    International Nuclear Information System (INIS)

    Maraschi, L.; Treves, A.; Tagliaferri, G.; Tanzi, E.G.; CNR, Istituto di Fisica Cosmica, Milan, Italy)

    1986-01-01

    All the ultraviolet spectra of the two bright BL Lacertae objects PKS 2155 - 304 and OJ 287 taken with the International Ultraviolet Explorer in the period 1978-1984 are examined. For each spectrum the best-fitting power law is determined and a correlation between spectral slope and intensity is searched for. The correlation, if present, is weak. This is discussed in terms of models of the continuum emission of active galactic nuclei. 31 references

  8. Variability of the BL Lacertae objects PKS 2155 - 304 and OJ 287 in the far-ultraviolet

    Energy Technology Data Exchange (ETDEWEB)

    Maraschi, L.; Treves, A.; Tagliaferri, G.; Tanzi, E.G.

    1986-05-01

    All the ultraviolet spectra of the two bright BL Lacertae objects PKS 2155 - 304 and OJ 287 taken with the International Ultraviolet Explorer in the period 1978-1984 are examined. For each spectrum the best-fitting power law is determined and a correlation between spectral slope and intensity is searched for. The correlation, if present, is weak. This is discussed in terms of models of the continuum emission of active galactic nuclei. 31 references.

  9. Brightness Alteration with Interweaving Contours

    Directory of Open Access Journals (Sweden)

    Sergio Roncato

    2012-12-01

    Full Text Available Chromatic induction is observed whenever the perceived colour of a target surface shifts towards the hue of a neighbouring surface. Some vivid manifestations may be seen in a white background where thin coloured lines have been drawn (assimilation or when lines of different colours are collinear (neon effect or adjacent (watercolour to each other. This study examines a particular colour induction that manifests in concomitance with an opposite effect of colour saturation (or anti-spread. The two phenomena can be observed when a repetitive pattern is drawn in which outline thin contours intercept wider contours or surfaces, colour spreading appear to fill the surface occupied by surfaces or thick lines whereas the background traversed by thin lines is seen as brighter or filled of a saturated white. These phenomena were first observed by Bozzi (1975 and Kanizsa (1979 in figural conditions that did not allow them to document their conjunction. Here we illustrate various manifestations of this twofold phenomenon and compare its effects with the known effects of brightness and colour induction. Some conjectures on the nature of these effects are discussed.

  10. Bright Sparks of Our Future!

    Science.gov (United States)

    Riordan, Naoimh

    2016-04-01

    My name is Naoimh Riordan and I am the Vice Principal of Rockboro Primary School in Cork City, South of Ireland. I am a full time class primary teacher and I teach 4th class, my students are aged between 9-10 years. My passion for education has developed over the years and grown towards STEM (Science, Technology, Engineering and Mathematics) subjects. I believe these subjects are the way forward for our future. My passion and beliefs are driven by the unique after school programme that I have developed. It is titled "Sparks" coming from the term Bright Sparks. "Sparks" is an after school programme with a difference where the STEM subjects are concentrated on through lessons such as Science, Veterinary Science Computer Animation /Coding, Eco engineering, Robotics, Magical Maths, Chess and Creative Writing. All these subjects are taught through activity based learning and are one-hour long each week for a ten-week term. "Sparks" is fully inclusive and non-selective which gives all students of any level of ability an opportunity to engage into these subjects. "Sparks" is open to all primary students in County Cork. The "Sparks" after school programme is taught by tutors from the different Universities and Colleges in Cork City. It works very well because the tutor brings their knowledge, skills and specialised equipment from their respective universities and in turn the tutor gains invaluable teaching practise, can trial a pilot programme in a chosen STEM subject and gain an insight into what works in the physical classroom.

  11. Designers predict a bright future

    International Nuclear Information System (INIS)

    Statton, T.D.

    1996-01-01

    As power plant designers and builders, there is a bright future for the industry. The demand for electricity will continue to grow, and the need for new plants will increase accordingly. But companies that develop and supply these plants must adapt to new ways of doing business if they expect to see the dawn of this new age. Several factors will have a profound effect on the generation and use of electricity in future years. Instant communications now reach all corners of the globe, making people everywhere aspire to a higher standard of living. The economic surge needed to satisfy these appetites will, in turn, be fed by a network of suppliers who are themselves restructuring to serve global markets, unimpeded by past nationalistic barriers to trade. The strong correlation between economic progress and the growing demand for electricity is well recognized. A ready supply of affordable electricity is a necessary underpinning for any economic expansion. As economies advance and jobs increase, electric demand grows geometrically, fueled by an ever-improving quality of life. Coupled with increasing demand is the worldwide trend toward privatization of the generation industry. The reasons may vary in different parts of the world, but the effect is the same--companies are battling intensely for the right to build or purchase generating facilities. Those companies, like the industry they serve, are themselves in a period of transition. Once a closed, monopolistic group of owners in a predominantly services-based market, they are, thanks to competitive forces, being driven steadily toward a product-based structure

  12. Absolute measurement of undulator radiation in the extreme ultraviolet

    International Nuclear Information System (INIS)

    Maezawa, H.; Kitamura, H.; Sasaki, T.; Mitani, S.; Osaka City Univ.; Suzuki, Y.; Kanamori, H.; Tamamushi, S.; Tokyo Univ.; Mikuni, A.; Tokyo Univ., Tanashi

    1983-01-01

    The spectral brightness of undulator radiation emitted by the model PMU-1 incorporated in the SOR-RING, the dedicated synchrotron radiation source in Tokyo, has been studied in the extreme ultraviolet region from 21.6 to 72.9 eV as a function of the electron energy #betta#, the field parameter K, and the angle of observation THETA in the absolute scale. A series of measurements covering the first and the second harmonic component of undulator radiation was compared with the fundamental formula lambdasub(n)=lambda 0 /2n#betta# 2 (1+K 2 /2+#betta# 2 THETA 2 ), and the effects of finite emittance were studied. The brightness at the first peak was smaller than the theoretical value, while an enhanced second harmonic component was observed. (orig.)

  13. Bright boys the making of information technology

    CERN Document Server

    Green, Tom

    2010-01-01

    Everything has a beginning. None was more profound-and quite as unexpected-than Information Technology. Here for the first time is the untold story of how our new age came to be and the bright boys who made it happen. What began on the bare floor of an old laundry building eventually grew to rival in size the Manhattan Project. The unexpected consequence of that journey was huge---what we now know as Information Technology. For sixty years the bright boys have been totally anonymous while their achievements have become a way of life for all of us. "Bright Boys" brings them home. By 1950 they'd

  14. Occupational applications of ultraviolet radiation

    International Nuclear Information System (INIS)

    Eriksen, P.

    1987-01-01

    A large population of workers are exposed to ultraviolet radiation in various occupational environments which often necessitates protection. Since ultraviolet radiation may create other environmental problems an occupational hazard- and protection evaluation can be complicated. Threshold Limit Values adopted by the American Conference of Governmental Industrial Hygienists (ACGIH) on ultraviolet radiation are used in most countries as guidelines for risk assessment and control measures. This review addresses the levels of ultraviolet radiation met in occupational environments, its measurement and evaluation, and discusses different protection methods. Ultraviolet lasers are beginning to find their way into industrial processes but are still limited in number and they will not be covered here. Emphasis is on broad band incoherent radiation in high risk environments such as welding, and on the evaluation of protective eyewear, see-through curtains and plastics. Other occupational risks associated with the emission of ultraviolet radiation are discussed

  15. Time-resolved brightness measurements by streaking

    Science.gov (United States)

    Torrance, Joshua S.; Speirs, Rory W.; McCulloch, Andrew J.; Scholten, Robert E.

    2018-03-01

    Brightness is a key figure of merit for charged particle beams, and time-resolved brightness measurements can elucidate the processes involved in beam creation and manipulation. Here we report on a simple, robust, and widely applicable method for the measurement of beam brightness with temporal resolution by streaking one-dimensional pepperpots, and demonstrate the technique to characterize electron bunches produced from a cold-atom electron source. We demonstrate brightness measurements with 145 ps temporal resolution and a minimum resolvable emittance of 40 nm rad. This technique provides an efficient method of exploring source parameters and will prove useful for examining the efficacy of techniques to counter space-charge expansion, a critical hurdle to achieving single-shot imaging of atomic scale targets.

  16. BrightStat.com: free statistics online.

    Science.gov (United States)

    Stricker, Daniel

    2008-10-01

    Powerful software for statistical analysis is expensive. Here I present BrightStat, a statistical software running on the Internet which is free of charge. BrightStat's goals, its main capabilities and functionalities are outlined. Three different sample runs, a Friedman test, a chi-square test, and a step-wise multiple regression are presented. The results obtained by BrightStat are compared with results computed by SPSS, one of the global leader in providing statistical software, and VassarStats, a collection of scripts for data analysis running on the Internet. Elementary statistics is an inherent part of academic education and BrightStat is an alternative to commercial products.

  17. Transparent ultraviolet photovoltaic cells.

    Science.gov (United States)

    Yang, Xun; Shan, Chong-Xin; Lu, Ying-Jie; Xie, Xiu-Hua; Li, Bing-Hui; Wang, Shuang-Peng; Jiang, Ming-Ming; Shen, De-Zhen

    2016-02-15

    Photovoltaic cells have been fabricated from p-GaN/MgO/n-ZnO structures. The photovoltaic cells are transparent to visible light and can transform ultraviolet irradiation into electrical signals. The efficiency of the photovoltaic cells is 0.025% under simulated AM 1.5 illumination conditions, while it can reach 0.46% under UV illumination. By connecting several such photovoltaic cells in a series, light-emitting devices can be lighting. The photovoltaic cells reported in this Letter may promise the applications in glass of buildings to prevent UV irradiation and produce power for household appliances in the future.

  18. Measuring brightness temperature distributions of plasma bunches

    International Nuclear Information System (INIS)

    Kirko, V.I.; Stadnichenko, I.A.

    1981-01-01

    The possibility of restoration of brightness temperature distribution along plasma jet on the base of a simple ultra high- speed photography and subsequent photometric treatment is shown. The developed technique has been applied for finding spectral radiation intensity and brightness temperature of plasma jets of a tubular gas-cumulative charge and explosive plasma compressor. The problem of shock wave front has been successfully solved and thus distribution of above parameters beginning from the region preceeding the shock wave has been obtained [ru

  19. Bright THz Instrument and Nonlinear THz Science

    Science.gov (United States)

    2017-10-30

    Report: Bright THz Instrument and Nonlinear THz Science The views, opinions and/or findings contained in this report are those of the author(s) and...Number: W911NF-16-1-0436 Organization: University of Rochester Title: Bright THz Instrument and Nonlinear THz Science Report Term: 0-Other Email: xi...exploring new cutting-edge research and broader applications, following the significant development of THz science and technology in the late 80’s, is the

  20. The surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    Phillipps, S.; Disney, M.

    1983-01-01

    It is proposed that Freeman's discovery that the extrapolated central surface brightness of spiral galaxies is approximately constant can be simply explained if the galaxies contain a spheroidal component which dominates the light in their outer isophotes. Calculations of an effective central surface brightness indicate a wide spread of values. This requires either a wide spread in disc properties or significant spheroidal components or, most probably, both. (author)

  1. The surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    Disney, M.; Phillipps, S.

    1985-01-01

    The intrinsic surface brightness Ssub(e) of 500 disc galaxies (0<=T<=9) drawn from the Second Reference Catalogue is computed and it is shown that Ssub(e) does not correlate significantly with Msub(B), (B-V) or type. This is consistent with the notion that there is a heavy selection bias in favour of disc galaxies with that particular surface brightness which allows inclusion in the catalogue over the largest volume of space. (author)

  2. Brightness masking is modulated by disparity structure.

    Science.gov (United States)

    Pelekanos, Vassilis; Ban, Hiroshi; Welchman, Andrew E

    2015-05-01

    The luminance contrast at the borders of a surface strongly influences surface's apparent brightness, as demonstrated by a number of classic visual illusions. Such phenomena are compatible with a propagation mechanism believed to spread contrast information from borders to the interior. This process is disrupted by masking, where the perceived brightness of a target is reduced by the brief presentation of a mask (Paradiso & Nakayama, 1991), but the exact visual stage that this happens remains unclear. In the present study, we examined whether brightness masking occurs at a monocular-, or a binocular-level of the visual hierarchy. We used backward masking, whereby a briefly presented target stimulus is disrupted by a mask coming soon afterwards, to show that brightness masking is affected by binocular stages of the visual processing. We manipulated the 3-D configurations (slant direction) of the target and mask and measured the differential disruption that masking causes on brightness estimation. We found that the masking effect was weaker when stimuli had a different slant. We suggest that brightness masking is partly mediated by mid-level neuronal mechanisms, at a stage where binocular disparity edge structure has been extracted. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. Differential Rotation via Tracking of Coronal Bright Points.

    Science.gov (United States)

    McAteer, James; Boucheron, Laura E.; Osorno, Marcy

    2016-05-01

    The accurate computation of solar differential rotation is important both as a constraint for, and evidence towards, support of models of the solar dynamo. As such, the use of Xray and Extreme Ultraviolet bright points to elucidate differential rotation has been studied in recent years. In this work, we propose the automated detection and tracking of coronal bright points (CBPs) in a large set of SDO data for re-evaluation of solar differential rotation and comparison to other results. The big data aspects, and high cadence, of SDO data mitigate a few issues common to detection and tracking of objects in image sequences and allow us to focus on the use of CBPs to determine differential rotation. The high cadence of the data allows to disambiguate individual CBPs between subsequent images by allowing for significant spatial overlap, i.e., by the fact that the CBPs will rotate a short distance relative to their size. The significant spatial overlap minimizes the effects of incorrectly detected CBPs by reducing the occurrence of outlier values of differential rotation. The big data aspects of the data allows to be more conservative in our detection of CBPs (i.e., to err on the side of missing CBPs rather than detecting extraneous CBPs) while still maintaining statistically larger populations over which to study characteristics. The ability to compute solar differential rotation through the automated detection and tracking of a large population of CBPs will allow for further analyses such as the N-S asymmetry of differential rotation, variation of differential rotation over the solar cycle, and a detailed study of the magnetic flux underlying the CBPs.

  4. Energy-exchange collisions of dark-bright-bright vector solitons.

    Science.gov (United States)

    Radhakrishnan, R; Manikandan, N; Aravinthan, K

    2015-12-01

    We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices.

  5. The Variability of Atmospheric Deuterium Brightness at Mars: Evidence for Seasonal Dependence

    Science.gov (United States)

    Mayyasi, Majd; Clarke, John; Bhattacharyya, Dolon; Deighan, Justin; Jain, Sonal; Chaffin, Michael; Thiemann, Edward; Schneider, Nick; Jakosky, Bruce

    2017-10-01

    The enhanced ratio of deuterium to hydrogen on Mars has been widely interpreted as indicating the loss of a large column of water into space, and the hydrogen content of the upper atmosphere is now known to be highly variable. The variation in the properties of both deuterium and hydrogen in the upper atmosphere of Mars is indicative of the dynamical processes that produce these species and propagate them to altitudes where they can escape the planet. Understanding the seasonal variability of D is key to understanding the variability of the escape rate of water from Mars. Data from a 15 month observing campaign, made by the Mars Atmosphere and Volatile Evolution Imaging Ultraviolet Spectrograph high-resolution echelle channel, are used to determine the brightness of deuterium as observed at the limb of Mars. The D emission is highly variable, with a peak in brightness just after southern summer solstice. The trends of D brightness are examined against extrinsic as well as intrinsic sources. It is found that the fluctuations in deuterium brightness in the upper atmosphere of Mars (up to 400 km), corrected for periodic solar variations, vary on timescales that are similar to those of water vapor fluctuations lower in the atmosphere (20-80 km). The observed variability in deuterium may be attributed to seasonal factors such as regional dust storm activity and subsequent circulation lower in the atmosphere.

  6. Synchronized observations of bright points from the solar photosphere to the corona

    Science.gov (United States)

    Tavabi, Ehsan

    2018-05-01

    One of the most important features in the solar atmosphere is the magnetic network and its relationship to the transition region (TR) and coronal brightness. It is important to understand how energy is transported into the corona and how it travels along the magnetic field lines between the deep photosphere and chromosphere through the TR and corona. An excellent proxy for transportation is the Interface Region Imaging Spectrograph (IRIS) raster scans and imaging observations in near-ultraviolet (NUV) and far-ultraviolet (FUV) emission channels, which have high time, spectral and spatial resolutions. In this study, we focus on the quiet Sun as observed with IRIS. The data with a high signal-to-noise ratio in the Si IV, C II and Mg II k lines and with strong emission intensities show a high correlation with TR bright network points. The results of the IRIS intensity maps and dopplergrams are compared with those of the Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) instruments onboard the Solar Dynamical Observatory (SDO). The average network intensity profiles show a strong correlation with AIA coronal channels. Furthermore, we applied simultaneous observations of the magnetic network from HMI and found a strong relationship between the network bright points in all levels of the solar atmosphere. These features in the network elements exhibited regions of high Doppler velocity and strong magnetic signatures. Plenty of corona bright points emission, accompanied by the magnetic origins in the photosphere, suggest that magnetic field concentrations in the network rosettes could help to couple the inner and outer solar atmosphere.

  7. Unperturbed moderator brightness in pulsed neutron sources

    International Nuclear Information System (INIS)

    Batkov, K.; Takibayev, A.; Zanini, L.; Mezei, F.

    2013-01-01

    The unperturbed neutron brightness of a moderator can be defined from the number of neutrons leaving the surface of a moderator completely surrounded by a reflector. Without openings for beam extraction, it is the maximum brightness that can be theoretically achieved in a moderator. The unperturbed brightness of a cylindrical cold moderator filled with pure para-H 2 was calculated using MCNPX; the moderator dimensions were optimised, for a fixed target and reflector geometry corresponding to the present concept for the ESS spallation source. This quantity does not depend on openings for beam extraction and therefore can be used for a first-round optimisation of a moderator, before effects due to beam openings are considered. We find that such an optimisation yields to a factor of 2 increase with respect to a conventional volume moderator, large enough to accommodate a viewed surface of 12×12 cm 2 : the unperturbed neutron brightness is maximum for a disc-shaped moderator of 15 cm diameter, 1.4 cm height. The reasons for this increase can be related to the properties of the scattering cross-section of para-H 2 , to the added reflector around the exit surface in the case of a compact moderator, and to a directionality effect. This large optimisation gain in the unperturbed brightness hints towards similar potentials for the perturbed neutron brightness, in particular in conjunction with advancing the optical quality of neutron delivery from the moderator to the sample, where by Liouville theorem the brightness is conserved over the beam trajectory, except for absorption and similar type losses

  8. Numerical evaluation of a 13.5-nm high-brightness microplasma extreme ultraviolet source

    Czech Academy of Sciences Publication Activity Database

    Hara, H.; Arai, G.; Dinh, T.H.; Jiang, W.; Miura, T.; Endo, Akira; Ejima, T.; Li, B.; Dunne, P.; O'Sullivan, G.; Sunahara, A.; Higashiguchi, T.

    2015-01-01

    Roč. 118, č. 19 (2015), s. 1-7, č. článku 193301. ISSN 0021-8979 Institutional support: RVO:68378271 Keywords : laser-produced plasmas * 4D-4F emissions resonances * collisions * dynamics Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 2.101, year: 2015

  9. GALEX FAR-ULTRAVIOLET COLOR SELECTION OF UV-BRIGHT HIGH-REDSHIFT QUASARS

    International Nuclear Information System (INIS)

    Worseck, Gabor; Prochaska, J. Xavier

    2011-01-01

    We study the small population of high-redshift (z em >2.7) quasars detected by the Galaxy Evolution Explorer(GALEX), whose far-UV emission is not extinguished by intervening H I Lyman limit systems. These quasars are of particular importance to detect intergalactic He II absorption along their sight lines. We correlate almost all verified z em >2.7 quasars to the GALEX GR4 source catalog covering ∼ 25,000 deg 2 , yielding 304 sources detected at signal-to-noise ratio (S/N) >3. However, ∼50% of these are only detected in the GALEX NUV band, signaling the truncation of the FUV flux by low-redshift optically thick Lyman limit systems. We exploit the GALEX UV color m FUV - m NUV to cull the most promising targets for follow-up studies, with blue (red) GALEX colors indicating transparent (opaque) sight lines. Extensive Monte Carlo simulations indicate an He II detection rate of ∼60% for quasars with m FUV - m NUV ∼ em ∼ 3 to be most promising for Hubble Space Telescope follow-up, with an additional 114 quasars if we consider S/N >2 detections in the FUV. Combining the statistical properties of H I absorbers with the Sloan Digital Sky Survey (SDSS) quasar luminosity function, we predict a large all-sky population of ∼200 quasars with z em >2.7 and i ∼ 304 em ∼ em ∼ em ∼< 3.5 quasars have likely underestimated their space density by selecting intergalactic medium sight lines with an excess of strong H I absorbers.

  10. Generation of Bright Phase-matched Circularly-polarized Extreme Ultraviolet High Harmonics

    Science.gov (United States)

    2014-12-08

    1995). 42. Eichmann , H. et al. Polarization-dependent high-order two-color mixing. Phys. Rev. A 51, R3414–R3417 (1995). 43. Fleischer, A., Kfir, O...calculations of polarization-dependent two- color high-harmonic generation. Phys. Rev. A 52, 2262–2278 (1995). 10. Eichmann , H. et al. polarization

  11. Intermittent episodes of bright light suppress myopia in the chicken more than continuous bright light.

    Science.gov (United States)

    Lan, Weizhong; Feldkaemper, Marita; Schaeffel, Frank

    2014-01-01

    Bright light has been shown a powerful inhibitor of myopia development in animal models. We studied which temporal patterns of bright light are the most potent in suppressing deprivation myopia in chickens. Eight-day-old chickens wore diffusers over one eye to induce deprivation myopia. A reference group (n = 8) was kept under office-like illuminance (500 lux) at a 10:14 light:dark cycle. Episodes of bright light (15 000 lux) were super-imposed on this background as follows. Paradigm I: exposure to constant bright light for either 1 hour (n = 5), 2 hours (n = 5), 5 hours (n = 4) or 10 hours (n = 4). Paradigm II: exposure to repeated cycles of bright light with 50% duty cycle and either 60 minutes (n = 7), 30 minutes (n = 8), 15 minutes (n = 6), 7 minutes (n = 7) or 1 minute (n = 7) periods, provided for 10 hours. Refraction and axial length were measured prior to and immediately after the 5-day experiment. Relative changes were analyzed by paired t-tests, and differences among groups were tested by one-way ANOVA. Compared with the reference group, exposure to continuous bright light for 1 or 2 hours every day had no significant protective effect against deprivation myopia. Inhibition of myopia became significant after 5 hours of bright light exposure but extending the duration to 10 hours did not offer an additional benefit. In comparison, repeated cycles of 1:1 or 7:7 minutes of bright light enhanced the protective effect against myopia and could fully suppress its development. The protective effect of bright light depends on the exposure duration and, to the intermittent form, the frequency cycle. Compared to the saturation effect of continuous bright light, low frequency cycles of bright light (1:1 min) provided the strongest inhibition effect. However, our quantitative results probably might not be directly translated into humans, but rather need further amendments in clinical studies.

  12. Proxy magnetometry of the photosphere: why are G-band bright points so bright?

    NARCIS (Netherlands)

    Rutten, R.J.; Kiselman, Dan; Voort, Luc Rouppe van der; Plez, Bertrand

    2000-01-01

    We discuss the formation of G-band bright points in terms of standard uxtube modeling, in particular the 1D LTE models constructed by Solanki and coworkers. Combined with LTE spectral synthesis they explain observed G-band bright point contrasts quite well. The G-band contrast increase over the

  13. A selective deficit in the appreciation and recognition of brightness: brightness agnosia?

    NARCIS (Netherlands)

    Nijboer, T.C.W.; Nys, G.M.S.; van der Smagt, M.J.; de Haan, E.H.F.

    2009-01-01

    We report a patient with extensive brain damage in the right hemisphere who demonstrated a severe impairment in the appreciation of brightness. Acuity, contrast sensitivity as well as luminance discrimination were normal, suggesting her brightness impairment is not a mere consequence of low-level

  14. Chandra's Darkest Bright Star: not so Dark after All?

    Science.gov (United States)

    Ayres, Thomas R.

    2008-11-01

    The Chandra High Resolution camera (HRC) has obtained numerous short exposures of the ultraviolet (UV)-bright star Vega (α Lyrae; HD 172167: A0 V), to calibrate the response of the detector to out-of-band (non-X-ray) radiation. A new analysis uncovered a stronger "blue leak" in the imaging section (HRC-I) than reported in an earlier study of Vega based on a subset of the pointings. The higher count rate—a factor of nearly 2 above prelaunch estimates—raised the possibility that genuine coronal X-rays might lurk among the out-of-band events. Exploiting the broader point-spread function of the UV leak compared with soft X-rays identified an excess of counts centered on the target, technically at 3σ significance. A number of uncertainties, however, prevent a clear declaration of a Vegan corona. A more secure result would be within reach of a deep uninterrupted HRC-I pointing.

  15. A selective deficit in the appreciation and recognition of brightness: brightness agnosia?

    Science.gov (United States)

    Nijboer, Tanja C W; Nys, Gudrun M S; van der Smagt, Maarten J; de Haan, Edward H F

    2009-01-01

    We report a patient with extensive brain damage in the right hemisphere who demonstrated a severe impairment in the appreciation of brightness. Acuity, contrast sensitivity as well as luminance discrimination were normal, suggesting her brightness impairment is not a mere consequence of low-level sensory impairments. The patient was not able to indicate the darker or the lighter of two grey squares, even though she was able to see that they differed. In addition, she could not indicate whether the lights in a room were switched on or off, nor was she able to differentiate between normal greyscale images and inverted greyscale images. As the patient recognised objects, colours, and shapes correctly, the impairment is specific for brightness. As low-level, sensory processing is normal, this specific deficit in the recognition and appreciation of brightness appears to be of a higher, cognitive level, the level of semantic knowledge. This appears to be the first report of 'brightness agnosia'.

  16. Plasmonic EIT-like switching in bright-dark-bright plasmon resonators.

    Science.gov (United States)

    Chen, Junxue; Wang, Pei; Chen, Chuncong; Lu, Yonghua; Ming, Hai; Zhan, Qiwen

    2011-03-28

    In this paper we report the study of the electromagnetically induced transparency (EIT)-like transmission in the bright-dark-bright plasmon resonators. It is demonstrated that the interferences between the dark plasmons excited by two bright plasmon resonators can be controlled by the incident light polarization. The constructive interference strengthens the coupling between the bright and dark resonators, leading to a more prominent EIT-like transparency window of the metamaterial. In contrary, destructive interference suppresses the coupling between the bright and dark resonators, destroying the interference pathway that forms the EIT-like transmission. Based on this observation, the plasmonic EIT switching can be realized by changing the polarization of incident light. This phenomenon may find applications in optical switching and plasmon-based information processing.

  17. STARS4ALL Night Sky Brightness Photometer

    Directory of Open Access Journals (Sweden)

    Jaime Zamorano

    2017-06-01

    Full Text Available We present the main features of TESS-W, the first version of a series of inexpensive but reliable photometers that will be used to measure night sky brightness. The bandpass is extended to the red with respect of that of the Sky Quality Meter (SQM. TESS-W connects to a router via WIFI and it sends automatically the brightness values to a data repository using Internet of Things protocols. The device includes an infrared sensor to estimate the cloud coverage. It is designed for fixed stations to monitor the evolution of the sky brightness. The photometer could also be used in local mode connected to a computer or tablet to gather data from a moving vehicle. The photometer is being developed within STARS4ALL project, a collective awareness platform for promoting dark skies in Europe, funded by the EU. We intend to extend the existing professional networks to a citizen-based network of photometers. 

  18. Increasing the brightness of light sources

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Ling

    2006-11-16

    In this work the principle of light recycling is applied to artificial light sources in order to achieve brightness enhancement. Firstly, the feasibilities of increasing the brightness of light sources via light recycling are examined theoretically, based on the fundamental laws of thermodynamics including Kirchhoff's law on radiation, Planck's law, Lambert-Beer's law, the etendue conservation and the brightness theorem. From an experimental viewpoint, the radiation properties of three different kinds of light sources including short-arc lamps, incandescent lamps and LEDs characterized by their light-generating mechanisms are investigated. These three types of sources are used in light recycling experiments, for the purpose of 1. validating the intrinsic light recycling effect in light sources, e. g. the intrinsic light recycling effect in incandescent lamps stemming from the coiled filament structure. 2. acquiring the required parameters for establishing physical models, e.g. the emissivity/absorptivity of the short-arc lamps, the intrinsic reflectivity and the external quantum efficiency of LEDs. 3. laying the foundations for designing optics aimed at brightness enhancement according to the characteristics of the sources and applications. Based on the fundamental laws and experiments, two physical models for simulating the radiance distribution of light sources are established, one for thermal filament lamps, the other for luminescent sources, LEDs. As validation of the theoretical and experimental investigation of the light recycling effect, an optical device, the Carambola, is designed for achieving deterministic and multiple light recycling. The Carambola has the function of a concentrator. In order to achieve the maximum possible brightness enhancement with the Carambola, several combinations of sources and Carambolas are modelled in ray-tracing simulations. Sources with different light-emitting mechanisms and different radiation properties

  19. Improving Assessment of Lifetime Solar Ultraviolet Radiation Exposure in Epidemiologic Studies: Comparison of Ultraviolet Exposure Assessment Methods in a Nationwide United States Occupational Cohort.

    Science.gov (United States)

    Little, Mark P; Tatalovich, Zaria; Linet, Martha S; Fang, Michelle; Kendall, Gerald M; Kimlin, Michael G

    2018-06-13

    Solar ultraviolet radiation is the primary risk factor for skin cancers and sun-related eye disorders. Estimates of individual ambient ultraviolet irradiance derived from ground-based solar measurements and from satellite measurements have rarely been compared. Using self-reported residential history from 67,189 persons in a nationwide occupational US radiologic technologists cohort, we estimated ambient solar irradiance using data from ground-based meters and noontime satellite measurements. The mean distance-moved from city of longest residence in childhood increased from 137.6 km at ages 13-19 to 870.3 km at ages ≥65, with corresponding increases in absolute latitude-difference moved. At ages 20/40/60/80, the Pearson/Spearman correlation coefficients of ground-based and satellite-derived solar potential ultraviolet exposure, using irradiance and cumulative radiant-exposure metrics, were high (=0.87-0.92). There was also moderate correlation (Pearson/Spearman correlation coefficients=0.51-0.60) between irradiance at birth and at last-known address, for ground-based and satellite data. Satellite-based lifetime estimates of ultraviolet radiation were generally 14-15% lower than ground-based estimates, albeit with substantial uncertainties, possibly because ground-based estimates incorporate fluctuations in cloud and ozone, which are incompletely incorporated in the single noontime satellite-overpass ultraviolet value. If confirmed elsewhere, the findings suggest that ground-based estimates may improve exposure-assessment accuracy and potentially provide new insights into ultraviolet-radiation-disease relationships in epidemiologic studies. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  20. Richard Bright and his neurological studies.

    Science.gov (United States)

    Pearce, J M S

    2009-01-01

    Richard Bright was one of the famous triumvirate of Guy's Hospital physicians in the Victorian era. Remembered for his account of glomerulonephritis (Bright's disease) he also made many important and original contributions to medicine and neurology. These included his work on cortical epileptogenesis, descriptions of simple partial (Jacksonian) seizures, infantile convulsions, and a variety of nervous diseases. Most notable were his reports of neurological studies including papers on traumatic tetanus, syringomyelia, arteries of the brain, contractures of spinal origin, tumours of the base of the brain, and narcolepsy. His career and these contributions are outlined. Copyright 2009 S. Karger AG, Basel.

  1. Human CD56bright NK Cells

    DEFF Research Database (Denmark)

    Michel, Tatiana; Poli, Aurélie; Cuapio, Angelica

    2016-01-01

    Human NK cells can be subdivided into various subsets based on the relative expression of CD16 and CD56. In particular, CD56(bright)CD16(-/dim) NK cells are the focus of interest. They are considered efficient cytokine producers endowed with immunoregulatory properties, but they can also become c...... NK cell subsets is not fully defined, nor is their precise hematopoietic origin. In this article, we summarize recent studies about CD56(bright) NK cells in health and disease and briefly discuss the current controversies surrounding them....

  2. Diagnostics for high-brightness beams

    International Nuclear Information System (INIS)

    Shafer, R.E.

    1990-01-01

    Special techniques are required for beam diagnostics on high-brightness particle beams. Examples of high-brightness beams include low-emittance proton linacs (either pulsed or CW), electron linacs suitable for free-electron-laser applications, and future linear colliders. Non-interceptive and minimally-interceptive techniques for measuring beam current, position, profile, and transverse and longitudinal emittance will be reviewed. Included will be stripline, wire scanner, laser neutralization, beam-beam scattering, interceptive microgratings, spontaneous emission, optical transition radiation, and other techniques. 24 refs

  3. Surprise Ultraviolet Party in the Sky

    Science.gov (United States)

    2005-01-01

    Galaxies aren't the only objects filling up the view of NASA's Galaxy Evolution Explorer. Since its launch in 2003, the space telescope -- originally designed to observe galaxies across the universe in ultraviolet light -- has discovered a festive sky blinking with flaring and erupting stars, as well as streaking asteroids, satellites and space debris. A group of six streaking objects -- the identities of which remain unknown -- can be seen here flying across the telescope's sight in this sped-up movie. The two brightest objects appear to perform a sharp turn then travel in the reverse direction. This illusion is most likely the result of the Galaxy Evolution Explorer overtaking the objects as it orbits around Earth. Careful inspection reveals four additional faint objects with the same timing and behavior. These faint objects are easiest to see during the retrograde portion of their paths. Three appear between the two bright sources, and one is above them, near the edge of the field of view. These bonus objects are being collected in to public catalogues for other astronomers to study.

  4. AN UPDATED ULTRAVIOLET CATALOG OF GALEX NEARBY GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yu; Zou, Hu; Liu, JiFeng; Wang, Song, E-mail: ybai@nao.cas.cn, E-mail: zouhu@nao.cas.cn, E-mail: jfliu@nao.cas.cn, E-mail: songw@nao.cas.cn [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang Distict, 100012 Beijing (China)

    2015-09-15

    The ultraviolet (UV) catalog of nearby galaxies compiled by Gil de Paz et al. presents the integrated photometry and surface brightness profiles for 1034 nearby galaxies observed by GALEX. We provide an updated catalog of 4138 nearby galaxies based on the latest Genral Release (GR6/GR7) of GALEX. These galaxies are selected from HyperLeda with apparent diameters larger than 1′. From the surface brightness profiles accurately measured using the deep NUV and FUV images, we have calculated the asymptotic magnitudes, aperture (D25) magnitudes, colors, structural parameters (effective radii and concentration indices), luminosities, and effective surface brightness for these galaxies. Archival optical and infrared photometry from HyperLeda, 2MASS, and IRAS are also integrated into the catalog. Our parameter measurements and some analyses are consistent with those of Paz et al. The (FUV − K) color provides a good criterion to distinguish between early- and late-type galaxies, which can be improved further using the concentration indices. The IRX–β relation is reformulated with our UV-selected nearby galaxies.

  5. Ultraviolet photovoltaics: Share the spectrum

    Science.gov (United States)

    Milliron, Delia J.

    2017-08-01

    Electrically controlled windows require power to switch between transparent and tinted states. Now, an ultraviolet light-harvesting solar cell can power smart windows without compromising their control over heat and light.

  6. Solar ultraviolet radiation cataract.

    Science.gov (United States)

    Löfgren, Stefan

    2017-03-01

    Despite being a treatable disease, cataract is still the leading cause for blindness in the world. Solar ultraviolet radiation is epidemiologically linked to cataract development, while animal and in vitro studies prove a causal relationship. However, the pathogenetic pathways for the disease are not fully understood and there is still no perfect model for human age related cataract. This non-comprehensive overview focus on recent developments regarding effects of solar UV radiation wavebands on the lens. A smaller number of fundamental papers are also included to provide a backdrop for the overview. Future studies are expected to further clarify the cellular and subcellular mechanisms for UV radiation-induced cataract and especially the isolated or combined temporal and spatial effects of UVA and UVB in the pathogenesis of human cataract. Regardless of the cause for cataract, there is a need for advances in pharmaceutical or other treatment modalities that do not require surgical replacement of the lens. Copyright © 2016. Published by Elsevier Ltd.

  7. Ultraviolet radiation and cyanobacteria.

    Science.gov (United States)

    Rastogi, Rajesh Prasad; Sinha, Rajeshwar P; Moh, Sang Hyun; Lee, Taek Kyun; Kottuparambil, Sreejith; Kim, Youn-Jung; Rhee, Jae-Sung; Choi, Eun-Mi; Brown, Murray T; Häder, Donat-Peter; Han, Taejun

    2014-12-01

    Cyanobacteria are the dominant photosynthetic prokaryotes from an ecological, economical, or evolutionary perspective, and depend on solar energy to conduct their normal life processes. However, the marked increase in solar ultraviolet radiation (UVR) caused by the continuous depletion of the stratospheric ozone shield has fueled serious concerns about the ecological consequences for all living organisms, including cyanobacteria. UV-B radiation can damage cellular DNA and several physiological and biochemical processes in cyanobacterial cells, either directly, through its interaction with certain biomolecules that absorb in the UV range, or indirectly, with the oxidative stress exerted by reactive oxygen species. However, cyanobacteria have a long history of survival on Earth, and they predate the existence of the present ozone shield. To withstand the detrimental effects of solar UVR, these prokaryotes have evolved several lines of defense and various tolerance mechanisms, including avoidance, antioxidant production, DNA repair, protein resynthesis, programmed cell death, and the synthesis of UV-absorbing/screening compounds, such as mycosporine-like amino acids (MAAs) and scytonemin. This study critically reviews the current information on the effects of UVR on several physiological and biochemical processes of cyanobacteria and the various tolerance mechanisms they have developed. Genomic insights into the biosynthesis of MAAs and scytonemin and recent advances in our understanding of the roles of exopolysaccharides and heat shock proteins in photoprotection are also discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Ultraviolet radiation in Finland

    Energy Technology Data Exchange (ETDEWEB)

    Taalas, P.; Koskela, T.; Damski, J.; Supperi, A. [Finnish Meteorological Inst., Helsinki (Finland). Section of Ozone and UV Research; Kyroe, E. [Finnish Meteorological Inst., Sodankylae (Finland). Sodankylae Observatory

    1996-12-31

    Solar ultraviolet radiation is damaging for living organisms due to its high energy pro each photon. The UV radiation is often separated into three regions according to the wavelength: UVC (200-280 nm), UVB (280-320 nm) and UVA (320-400 nm). The most hazardous part, UVC is absorbed completely in the upper atmosphere by molecular oxygen. UVB radiation is absorbed by atmospheric ozone partly, and it is reaching Earth`s surface, as UVA radiation. Besides atmospheric ozone, very important factors in determining the intensity of UVB radiation globally are the solar zenith angle and cloudiness. It may be calculated from global ozone changes that the clear-sky UVB doses may have enhanced by 10-15 % during spring and 5-10 % during summer at the latitudes of Finland, following the decrease of total ozone between 1979-90. The Finnish ozone and UV monitoring activities have become a part of international activities, especially the EU Environment and Climate Programme`s research projects. The main national level effort has been the Finnish Academy`s climatic change programme, SILMU 1990-95. This presentation summarises the scientific results reached during the SILMU project

  9. Ultraviolet radiation in Finland

    Energy Technology Data Exchange (ETDEWEB)

    Taalas, P; Koskela, T; Damski, J; Supperi, A [Finnish Meteorological Inst., Helsinki (Finland). Section of Ozone and UV Research; Kyroe, E [Finnish Meteorological Inst., Sodankylae (Finland). Sodankylae Observatory

    1997-12-31

    Solar ultraviolet radiation is damaging for living organisms due to its high energy pro each photon. The UV radiation is often separated into three regions according to the wavelength: UVC (200-280 nm), UVB (280-320 nm) and UVA (320-400 nm). The most hazardous part, UVC is absorbed completely in the upper atmosphere by molecular oxygen. UVB radiation is absorbed by atmospheric ozone partly, and it is reaching Earth`s surface, as UVA radiation. Besides atmospheric ozone, very important factors in determining the intensity of UVB radiation globally are the solar zenith angle and cloudiness. It may be calculated from global ozone changes that the clear-sky UVB doses may have enhanced by 10-15 % during spring and 5-10 % during summer at the latitudes of Finland, following the decrease of total ozone between 1979-90. The Finnish ozone and UV monitoring activities have become a part of international activities, especially the EU Environment and Climate Programme`s research projects. The main national level effort has been the Finnish Academy`s climatic change programme, SILMU 1990-95. This presentation summarises the scientific results reached during the SILMU project

  10. The Eindhoven High-Brightness Electron Programme

    NARCIS (Netherlands)

    Brussaard, G.J.H.; Wiel, van der M.J.

    2004-01-01

    The Eindhoven High-Brightness programme is aimed at producing ultra-short intense electron bunches from compact accelerators. The RF electron gun is capable of producing 100 fs electron bunches at 7.5 MeV and 10 pC bunch charge. The DC/RF hybrid gun under development will produce bunches <75 fs at

  11. Discussion of high brightness rf linear accelerators

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1987-01-01

    The fundamental aspects of high-brightness rf linacs are outlined, showing the breadth and complexity of the technology and indicating that synergism with advancements in other areas is important. Areas of technology reviewed include ion sources, injectors, rf accelerator structures, beam dynamics, rf power, and automatic control

  12. Simultaneous brightness contrast of foraging Papilio butterflies

    Science.gov (United States)

    Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

    2012-01-01

    This study focuses on the sense of brightness in the foraging Japanese yellow swallowtail butterfly, Papilio xuthus. We presented two red discs of different intensity on a grey background to butterflies, and trained them to select one of the discs. They were successfully trained to select either a high intensity or a low intensity disc. The trained butterflies were tested on their ability to perceive brightness in two different protocols: (i) two orange discs of different intensity presented on the same intensity grey background and (ii) two orange discs of the same intensity separately presented on a grey background that was either higher or lower in intensity than the training background. The butterflies trained to high intensity red selected the orange disc of high intensity in protocol 1, and the disc on the background of low intensity grey in protocol 2. We obtained similar results in another set of experiments with purple discs instead of orange discs. The choices of the butterflies trained to low intensity red were opposite to those just described. Taken together, we conclude that Papilio has the ability to learn brightness and darkness of targets independent of colour, and that they have the so-called simultaneous brightness contrast. PMID:22179808

  13. Robust fitting of diurnal brightness temperature cycle

    CSIR Research Space (South Africa)

    Udahemuka, G

    2007-11-01

    Full Text Available for a pixel concerned. Robust fitting of observed Diurnal Temperature Cycle (DTC) taken over a day of a given pixel without cloud cover and other abnormally conditions such as fire can give a data based brightness temperature model for a given pixel...

  14. Ultraviolet Communication for Medical Applications

    Science.gov (United States)

    2015-06-01

    DEI procured several UVC phosphors and tested them with vacuum UV (VUV) excitation. Available emission peaks include: 226 nm, 230 nm, 234 nm, 242...SUPPLEMENTARY NOTES Report contains color. 14. ABSTRACT Under this Phase II SBIR effort, Directed Energy Inc.’s (DEI) proprietary ultraviolet ( UV ...15. SUBJECT TERMS Non-line-of-sight (NLOS), networking, optical communication, plasma-shells, short range, ultraviolet ( UV ) light 16. SECURITY

  15. ULTRAVIOLET TECHNOLOGY FOR FOOD PRESERVATION

    OpenAIRE

    Guedes, AMM; Novello, D; Mendes, GMD; Cristianini, M

    2009-01-01

    ULTRAVIOLET TECHNOLOGY FOR FOOD PRESERVATION This literature review article had as objective to gather information about ultraviolet (UV) technology utilization on the food industry, its effects and potential application. Aspects as the origin, concept and applications of the technology on the equipment industry and running mechanisms were approached. The application of UV radiation on food decontamination is still little used due its low penetration, but it is known that it can be easily app...

  16. Intermittent Episodes of Bright Light Suppress Myopia in the Chicken More than Continuous Bright Light

    OpenAIRE

    Lan, Weizhong; Feldkaemper, Marita; Schaeffel, Frank

    2014-01-01

    PURPOSE: Bright light has been shown a powerful inhibitor of myopia development in animal models. We studied which temporal patterns of bright light are the most potent in suppressing deprivation myopia in chickens. METHODS: Eight-day-old chickens wore diffusers over one eye to induce deprivation myopia. A reference group (n = 8) was kept under office-like illuminance (500 lux) at a 10:14 light:dark cycle. Episodes of bright light (15 000 lux) were super-imposed on this background as follows....

  17. Intermittent episodes of bright light suppress myopia in the chicken more than continuous bright light.

    Directory of Open Access Journals (Sweden)

    Weizhong Lan

    Full Text Available PURPOSE: Bright light has been shown a powerful inhibitor of myopia development in animal models. We studied which temporal patterns of bright light are the most potent in suppressing deprivation myopia in chickens. METHODS: Eight-day-old chickens wore diffusers over one eye to induce deprivation myopia. A reference group (n = 8 was kept under office-like illuminance (500 lux at a 10:14 light:dark cycle. Episodes of bright light (15 000 lux were super-imposed on this background as follows. Paradigm I: exposure to constant bright light for either 1 hour (n = 5, 2 hours (n = 5, 5 hours (n = 4 or 10 hours (n = 4. Paradigm II: exposure to repeated cycles of bright light with 50% duty cycle and either 60 minutes (n = 7, 30 minutes (n = 8, 15 minutes (n = 6, 7 minutes (n = 7 or 1 minute (n = 7 periods, provided for 10 hours. Refraction and axial length were measured prior to and immediately after the 5-day experiment. Relative changes were analyzed by paired t-tests, and differences among groups were tested by one-way ANOVA. RESULTS: Compared with the reference group, exposure to continuous bright light for 1 or 2 hours every day had no significant protective effect against deprivation myopia. Inhibition of myopia became significant after 5 hours of bright light exposure but extending the duration to 10 hours did not offer an additional benefit. In comparison, repeated cycles of 1:1 or 7:7 minutes of bright light enhanced the protective effect against myopia and could fully suppress its development. CONCLUSIONS: The protective effect of bright light depends on the exposure duration and, to the intermittent form, the frequency cycle. Compared to the saturation effect of continuous bright light, low frequency cycles of bright light (1:1 min provided the strongest inhibition effect. However, our quantitative results probably might not be directly translated into humans, but rather need further amendments in clinical studies.

  18. Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise.

    Science.gov (United States)

    Youngstedt, Shawn D; Kline, Christopher E; Elliott, Jeffrey A; Zielinski, Mark R; Devlin, Tina M; Moore, Teresa A

    2016-02-26

    Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210-2340 h, (2) treadmill exercise alone from 2210-2340 h, or (3) bright light (2210-2340 h) followed by exercise from 0410-0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect.

  19. Do Low Surface Brightness Galaxies Host Stellar Bars?

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes Sodi, Bernardo; Sánchez García, Osbaldo, E-mail: b.cervantes@irya.unam.mx, E-mail: o.sanchez@irya.unam.mx [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia, A.P. 3-72, C.P. 58089 Michoacán, México (Mexico)

    2017-09-20

    With the aim of assessing if low surface brightness galaxies host stellar bars and by studying the dependence of the occurrence of bars as a function of surface brightness, we use the Galaxy Zoo 2 data set to construct a large volume-limited sample of galaxies and then segregate these galaxies as having low or high surface brightness in terms of their central surface brightness. We find that the fraction of low surface brightness galaxies hosting strong bars is systematically lower than that found for high surface brightness galaxies. The dependence of the bar fraction on the central surface brightness is mostly driven by a correlation of the surface brightness with the spin and the gas richness of the galaxies, showing only a minor dependence on the surface brightness. We also find that the length of the bars is strongly dependent on the surface brightness, and although some of this dependence is attributed to the gas content, even at a fixed gas-to-stellar mass ratio, high surface brightness galaxies host longer bars than their low surface brightness counterparts, which we attribute to an anticorrelation of the surface brightness with the spin.

  20. Do Low Surface Brightness Galaxies Host Stellar Bars?

    International Nuclear Information System (INIS)

    Cervantes Sodi, Bernardo; Sánchez García, Osbaldo

    2017-01-01

    With the aim of assessing if low surface brightness galaxies host stellar bars and by studying the dependence of the occurrence of bars as a function of surface brightness, we use the Galaxy Zoo 2 data set to construct a large volume-limited sample of galaxies and then segregate these galaxies as having low or high surface brightness in terms of their central surface brightness. We find that the fraction of low surface brightness galaxies hosting strong bars is systematically lower than that found for high surface brightness galaxies. The dependence of the bar fraction on the central surface brightness is mostly driven by a correlation of the surface brightness with the spin and the gas richness of the galaxies, showing only a minor dependence on the surface brightness. We also find that the length of the bars is strongly dependent on the surface brightness, and although some of this dependence is attributed to the gas content, even at a fixed gas-to-stellar mass ratio, high surface brightness galaxies host longer bars than their low surface brightness counterparts, which we attribute to an anticorrelation of the surface brightness with the spin.

  1. Bright solitons in Bose-Fermi mixtures

    International Nuclear Information System (INIS)

    Karpiuk, Tomasz; Brewczyk, Miroslaw; RzaPewski, Kazimierz

    2006-01-01

    We consider the formation of bright solitons in a mixture of Bose and Fermi degenerate gases confined in a three-dimensional elongated harmonic trap. The Bose and Fermi atoms are assumed to effectively attract each other whereas bosonic atoms repel each other. Strong enough attraction between bosonic and fermionic components can change the character of the interaction within the bosonic cloud from repulsive to attractive making thus possible the generation of bright solitons in the mixture. On the other hand, such structures might be in danger due to the collapse phenomenon existing in attractive gases. We show, however, that under some conditions (defined by the strength of the Bose-Fermi components attraction) the structures which neither spread nor collapse can be generated. For elongated enough traps the formation of solitons is possible even at the 'natural' value of the mutual Bose-Fermi ( 87 Rb- 40 K in our case) scattering length

  2. Harmful effects of ultraviolet radiation

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    Tanning for cosmetic purposes by sunbathing or by using artificial tanning devices is widespread. The hazards associated with exposure to ultraviolet radiation are of concern to the medical profession. Depending on the amount and form of the radiation, as well as on the skin type of the individual exposed, ultraviolet radiation causes erythema, sunburn, photodamage (photoaging), photocarcinogenesis, damage to the eyes, alteration of the immune system of the skin, and chemical hypersensitivity. Skin cancers most commonly produced by ultraviolet radiation are basal and squamous cell carcinomas. There also is much circumstantial evidence that the increase in the incidence of cutaneous malignant melanoma during the past half century is related to increased sun exposure, but this has not been proved. Effective and cosmetically acceptable sunscreen preparations have been developed that can do much to prevent or reduce most harmful effects to ultraviolet radiation if they are applied properly and consistently. Other safety measures include (1) minimizing exposure to ultraviolet radiation, (2) being aware of reflective surfaces while in the sun, (3) wearing protective clothing, (4) avoiding use of artificial tanning devices, and (5) protecting infants and children

  3. Future Directions in Ultraviolet Spectroscopy

    Science.gov (United States)

    Sonneborn, George (Editor); Moos, Warren; VanSteenberg, Michael

    2009-01-01

    The 'Future Directions in Ultraviolet Spectroscopy' conference was inspired by the accomplishments of the Far Ultraviolet Spectroscopic Explorer (FUSE) Mission. The FUSE mission was launched in June 1999 and spent over eight years exploring the far-ultraviolet universe, gathering over 64 million seconds of high-resolution spectral data on nearly 3000 astronomical targets. The goal of this conference was not only to celebrate the accomplishments of FUSE, but to look toward the future and understand the major scientific drivers for the ultraviolet capabilities of the next generation fo space observatories. Invited speakers presented discussions based on measurements made by FUSE and other ultraviolet instruments, assessed their connection with measurements made with other techniques and, where appropriate, discussed the implications of low-z measurements for high-z phenomena. In addition to the oral presentations, many participants presented poster papers. The breadth of these presentation made it clear that much good science is still in progress with FUSE data and that these result will continue to have relevance in many scientific areas.

  4. High-brightness H/sup -/ accelerators

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1987-01-01

    Neutral particle beam (NPB) devices based on high-brightness H/sup -/ accelerators are an important component of proposed strategic defense systems. The basic rational and R and D program are outlined and examples given of the underlying technology thrusts toward advanced systems. Much of the research accomplished in the past year is applicable to accelerator systems in general; some of these activities are discussed

  5. Brightness of synchrotron radiation from wigglers

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2014-12-01

    According to literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so called 'depth-of-field' effects. In fact, the particle beam cross section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. In the geometrical optics limit computations can be performed analytically. Within this limit, we restrict ourselves to the case of the beam size-dominated regime, which is typical for synchrotron radiation facilities in the X-ray wavelength range. We give a direct demonstration of the fact that the apparent horizontal source size is broadened in proportion to the beamline opening angle and to the length of the wiggler. While this effect is well-understood, a direct proof appears not to have been given elsewhere. We consider the problem of the calculation of the wiggler source size by means of numerical simulations alone, which play the same role of an experiment. We report a significant numerical disagreement between exact calculations and approximations currently used in literature.

  6. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Steven Winter Associates, Inc., Norwalk, CT (United States); Butterfield, Karla [Steven Winter Associates, Inc., Norwalk, CT (United States)

    2016-03-01

    With funding from the Building America Program, part of the U.S. Department of Energy Building Technologies Office, the Consortium for Advanced Residential Buildings (CARB) worked with BrightBuilt Home (BBH) to evaluate and optimize building systems. CARB’s work focused on a home built by Black Bros. Builders in Lincolnville, Maine (International Energy Conservation Code Climate Zone 6). As with most BBH projects to date, modular boxes were built by Keiser Homes in Oxford, Maine.

  7. The surface brightness of spiral galaxies: Pt. 4

    International Nuclear Information System (INIS)

    Phillipps, S.; Disney, M.; Ohio State Univ., Columbus

    1988-01-01

    Using measurements from IRAS correlations are found between optical surface brightness and both infrared-to-optical flux ratio and infrared colour temperature, in the sense that galaxies with high surface brightness have higher FIR emission and higher temperatures. (author)

  8. Search for bright stars with infrared excess

    Energy Technology Data Exchange (ETDEWEB)

    Raharto, Moedji, E-mail: moedji@as.itb.ac.id [Astronomy Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

    2014-03-24

    Bright stars, stars with visual magnitude smaller than 6.5, can be studied using small telescope. In general, if stars are assumed as black body radiator, then the color in infrared (IR) region is usually equal to zero. Infrared data from IRAS observations at 12 and 25μm (micron) with good flux quality are used to search for bright stars (from Bright Stars Catalogues) with infrared excess. In magnitude scale, stars with IR excess is defined as stars with IR color m{sub 12}−m{sub 25}>0; where m{sub 12}−m{sub 25} = −2.5log(F{sub 12}/F{sub 25})+1.56, where F{sub 12} and F{sub 25} are flux density in Jansky at 12 and 25μm, respectively. Stars with similar spectral type are expected to have similar color. The existence of infrared excess in the same spectral type indicates the existence of circum-stellar dust, the origin of which is probably due to the remnant of pre main-sequence evolution during star formation or post AGB evolution or due to physical process such as the rotation of those stars.

  9. Condensate bright solitons under transverse confinement

    International Nuclear Information System (INIS)

    Salasnich, L.; Reatto, L.; Parola, A.

    2002-01-01

    We investigate the dynamics of Bose-Einstein condensate bright solitons made of alkali-metal atoms with negative scattering length and under harmonic confinement in the transverse direction. Contrary to the one-dimensional (1D) case, the 3D bright soliton exists only below a critical attractive interaction that depends on the extent of confinement. Such a behavior is also found in multisoliton condensates with box boundary conditions. We obtain numerical and analytical estimates of the critical strength beyond which the solitons do not exist. By using an effective 1D nonpolynomial nonlinear Schroedinger equation, which accurately takes into account the transverse dynamics of cigarlike condensates, we numerically simulate the dynamics of the 'soliton train' reported in a recent experiment [Nature (London) 417, 150 (2002)]. Then, analyzing the macroscopic quantum tunneling of the bright soliton on a Gaussian barrier, we find that its interference in the tunneling region is strongly suppressed with respect to nonsolitonic case; moreover, the tunneling through a barrier breaks the shape invariance of the matter wave. Finally, we show that the collapse of the soliton is induced by the scattering on the barrier or by the collision with another matter wave when the density reaches a critical value, for which we derive an accurate analytical formula

  10. Possible Bright Starspots on TRAPPIST-1

    Science.gov (United States)

    Morris, Brett M.; Agol, Eric; Davenport, James R. A.; Hawley, Suzanne L.

    2018-04-01

    The M8V star TRAPPIST-1 hosts seven roughly Earth-sized planets and is a promising target for exoplanet characterization. Kepler/K2 Campaign 12 observations of TRAPPIST-1 in the optical show an apparent rotational modulation with a 3.3-day period, though that rotational signal is not readily detected in the Spitzer light curve at 4.5 μm. If the rotational modulation is due to starspots, persistent dark spots can be excluded from the lack of photometric variability in the Spitzer light curve. We construct a photometric model for rotational modulation due to photospheric bright spots on TRAPPIST-1 that is consistent with both the Kepler and Spitzer light curves. The maximum-likelihood model with three spots has typical spot sizes of R spot/R ⋆ ≈ 0.004 at temperature T spot ≳ 5300 ± 200 K. We also find that large flares are observed more often when the brightest spot is facing the observer, suggesting a correlation between the position of the bright spots and flare events. In addition, these flares may occur preferentially when the spots are increasing in brightness, which suggests that the 3.3-day periodicity may not be a rotational signal, but rather a characteristic timescale of active regions.

  11. Ultraviolet-radiation-curable paints

    Energy Technology Data Exchange (ETDEWEB)

    Grosset, A M; Su, W F.A.; Vanderglas, E

    1981-09-30

    In product finishing lines, ultraviolet radiation curing of paints on prefabricated structures could be more energy efficient than curing by natural gas fired ovens, and could eliminate solvent emission. Diffuse ultraviolet light can cure paints on three dimensional metal parts. In the uv curing process, the spectral output of radiation sources must complement the absorption spectra of pigments and photoactive agents. Photosensitive compounds, such as thioxanthones, can photoinitiate unsaturated resins, such as acrylated polyurethanes, by a free radical mechanism. Newly developed cationic photoinitiators, such as sulfonium or iodonium salts (the so-called onium salts) of complex metal halide anions, can be used in polymerization of epoxy paints by ultraviolet light radiation. One-coat enamels, topcoats, and primers have been developed which can be photoinitiated to produce hard, adherent films. This process has been tested in a laboratory scale unit by spray coating these materials on three-dimensional objects and passing them through a tunnel containing uv lamps.

  12. Star formation and the surface brightness of spiral galaxies

    International Nuclear Information System (INIS)

    Phillipps, S.; Disney, M.

    1985-01-01

    The (blue) surface brightness of spiral galaxies is significantly correlated with their Hα linewidth. This can be most plausibly interpreted as a correlation of surface brightness with star formation rate. There is also a significant difference in surface brightness between galaxies forming stars in a grand design spiral pattern and those with floc star formation regions. (author)

  13. Ultraviolet spectrophotometry of three LINERs

    Science.gov (United States)

    Goodrich, R. W.; Keel, W. C.

    1986-01-01

    Three galaxies known to be LINERs were observed spectroscopically in the ultraviolet in an attempt to detect the presumed nonthermal continuum source thought to be the source of photoionization in the nuclei. NGC 4501 was found to be too faint for study with the IUE spectrographs, while NGC 5005 had an extended ultraviolet light profile. Comparison with the optical light profile of NGC 5005 indicates that the ultraviolet source is distributed spatially in the same manner as the optical starlight, probably indicating that the ultraviolet excess is due to a component of hot stars in the nucleus. These stars contribute detectable absorption features longward of 2500 A; together with optical data, the IUE spectra suggest a burst of star formation about 1 billion yr ago, with a lower rate continuing to produce a few OB stars. In NGC 4579, a point source contributing most of the ultraviolet excess is found that is much different than the optical light distribution. Furthermore, the ultraviolet to X-ray spectral index in NGC 4579 is 1.4, compatible with the UV to X-ray indices found for samples of Seyfert galaxies. This provides compelling evidence for the detection of the photoionizing continuum in NGC 4579 and draws the research fields of normal galaxies and active galactic nuclei closer together. The emission-line spectrum of NGC 4579 is compared with calculations from a photoionization code, CLOUDY, and several shock models. The photoionization code is found to give superior results, adding to the increasing weight of evidence that the LINER phenomenon is essentially a scaled-down version of the Seyfert phenomenon.

  14. Illuminating Low Surface Brightness Galaxies with the Hyper Suprime-Cam Survey

    Science.gov (United States)

    Greco, Johnny P.; Greene, Jenny E.; Strauss, Michael A.; Macarthur, Lauren A.; Flowers, Xzavier; Goulding, Andy D.; Huang, Song; Kim, Ji Hoon; Komiyama, Yutaka; Leauthaud, Alexie; Leisman, Lukas; Lupton, Robert H.; Sifón, Cristóbal; Wang, Shiang-Yu

    2018-04-01

    We present a catalog of extended low surface brightness galaxies (LSBGs) identified in the Wide layer of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). Using the first ∼200 deg2 of the survey, we have uncovered 781 LSBGs, spanning red (g ‑ i ≥ 0.64) and blue (g ‑ i r eff = 2.″5–14″), our sample is likely dominated by low-redshift objects. We define LSBGs to have mean surface brightnesses {\\bar{μ }}eff}(g)> 24.3 mag arcsec‑2, which allows nucleated galaxies into our sample. As a result, the central surface brightness distribution spans a wide range of μ 0(g) = 18–27.4 mag arcsec‑2, with 50% and 95% of galaxies fainter than 24.3 and 22 mag arcsec‑2, respectively. Furthermore, the surface brightness distribution is a strong function of color, with the red distribution being much broader and generally fainter than that of the blue LSBGs, and this trend shows a clear correlation with galaxy morphology. Red LSBGs typically have smooth light profiles that are well characterized by single-component Sérsic functions. In contrast, blue LSBGs tend to have irregular morphologies and show evidence for ongoing star formation. We cross-match our sample with existing optical, H I, and ultraviolet catalogs to gain insight into the physical nature of the LSBGs. We find that our sample is diverse, ranging from dwarf spheroidals and ultradiffuse galaxies in nearby groups to gas-rich irregulars to giant LSB spirals, demonstrating the potential of the HSC-SSP to provide a truly unprecedented view of the LSBG population.

  15. Ultraviolet light curves of U Geminorum and VW Hydri

    International Nuclear Information System (INIS)

    Wu, C.-C.; Panek, R.J.; Holm, A.V.; Schiffer, F.H. III

    1982-01-01

    Ultraviolet light curves have been obtained for the quiescent dwarf novae U Gem and VW Hyi. The amplitude of the hump associated with the accretion hot spot is much smaller in the UV than in the visible. This implies that the bright spot temperature is roughly 12000 K if it is optically thick. A hotter spot would have to be optically thin in the near UV. The flux distribution of U Gem in quiescence cannot be fitted by model spectra of steady state, viscous accretion disks. The absolute luminosity, the flux distribution, and the far UV spectrum suggest that the primary star is visible in the far UV. The optical-UV flux distribution of VW Hyi could be matched roughly by the authors' model accretion disks, but the fitting is poorly constrained due to the uncertainty in its distance. (Auth.)

  16. Electromagnetically induced transparency control in terahertz metasurfaces based on bright-bright mode coupling

    Science.gov (United States)

    Yahiaoui, R.; Burrow, J. A.; Mekonen, S. M.; Sarangan, A.; Mathews, J.; Agha, I.; Searles, T. A.

    2018-04-01

    We demonstrate a classical analog of electromagnetically induced transparency (EIT) in a highly flexible planar terahertz metamaterial (MM) comprised of three-gap split-ring resonators. The keys to achieve EIT in this system are the frequency detuning and hybridization processes between two bright modes coexisting in the same unit cell as opposed to bright-dark modes. We present experimental verification of two bright modes coupling for a terahertz EIT-MM in the context of numerical results and theoretical analysis based on a coupled Lorentz oscillator model. In addition, a hybrid variation of the EIT-MM is proposed and implemented numerically to dynamically tune the EIT window by incorporating photosensitive silicon pads in the split gap region of the resonators. As a result, this hybrid MM enables the active optical control of a transition from the on state (EIT mode) to the off state (dipole mode).

  17. Ultraviolet observations of AM Herculis

    International Nuclear Information System (INIS)

    Tanzi, E.G.; Treves, A.; Milan Univ.; Sandford, M.C.W.; Willis, A.J.; Wilson, R.

    1980-01-01

    Seven ultraviolet spectra (1100-3200 Angstroem) of AM Her were obtained with the low resolution spectrometer of the IUE satellite. Strong emission features appear superimposed on a well defined continuum which is well fitted by a Fsub(lambda) D lambda -2 law. The observations are compared with the expectations from models of the source. (orig.) 891 WL/orig. 892 HIS

  18. Ultraviolet light and cutaneous lupus

    NARCIS (Netherlands)

    Bijl, Marc; Kallenberg, Cees G. M.

    2006-01-01

    Exposure to ultraviolet (UV) light is one of the major factors known to trigger cutaneous disease activity in (systemic) lupus erythematosus patients. UV light, UVB in particular, is a potent inducer of apoptosis. Currently, disturbed clearance of apoptotic cells is one of the concepts explaining

  19. Investigating the Bright End of LSST Photometry

    Science.gov (United States)

    Ojala, Elle; Pepper, Joshua; LSST Collaboration

    2018-01-01

    The Large Synoptic Survey Telescope (LSST) will begin operations in 2022, conducting a wide-field, synoptic multiband survey of the southern sky. Some fraction of objects at the bright end of the magnitude regime observed by LSST will overlap with other wide-sky surveys, allowing for calibration and cross-checking between surveys. The LSST is optimized for observations of very faint objects, so much of this data overlap will be comprised of saturated images. This project provides the first in-depth analysis of saturation in LSST images. Using the PhoSim package to create simulated LSST images, we evaluate saturation properties of several types of stars to determine the brightness limitations of LSST. We also collect metadata from many wide-field photometric surveys to provide cross-survey accounting and comparison. Additionally, we evaluate the accuracy of the PhoSim modeling parameters to determine the reliability of the software. These efforts will allow us to determine the expected useable data overlap between bright-end LSST images and faint-end images in other wide-sky surveys. Our next steps are developing methods to extract photometry from saturated images.This material is based upon work supported in part by the National Science Foundation through Cooperative Agreement 1258333 managed by the Association of Universities for Research in Astronomy (AURA), and the Department of Energy under Contract No. DE-AC02-76SF00515 with the SLAC National Accelerator Laboratory. Additional LSST funding comes from private donations, grants to universities, and in-kind support from LSSTC Institutional Members.Thanks to NSF grant PHY-135195 and the 2017 LSSTC Grant Award #2017-UG06 for making this project possible.

  20. Selection effects in the bivariate brightness distribution for spiral galaxies

    International Nuclear Information System (INIS)

    Phillipps, S.; Disney, M.

    1986-01-01

    The joint distribution of total luminosity and characteristic surface brightness (the bivariate brightness distribution) is investigated for a complete sample of spiral galaxies in the Virgo cluster. The influence of selection and physical limits of various kinds on the apparent distribution are detailed. While the distribution of surface brightness for bright galaxies may be genuinely fairly narrow, faint galaxies exist right across the (quite small) range of accessible surface brightnesses so no statement can be made about the true extent of the distribution. The lack of high surface brightness bright galaxies in the Virgo sample relative to an overall RC2 sample (mostly field galaxies) supports the contention that the star-formation rate is reduced in the inner region of the cluster for environmental reasons. (author)

  1. Raman beam combining for laser brightness enhancement

    Science.gov (United States)

    Dawson, Jay W.; Allen, Graham S.; Pax, Paul H.; Heebner, John E.; Sridharan, Arun K.; Rubenchik, Alexander M.; Barty, Chrisopher B. J.

    2015-10-27

    An optical source capable of enhanced scaling of pulse energy and brightness utilizes an ensemble of single-aperture fiber lasers as pump sources, with each such fiber laser operating at acceptable pulse energy levels. Beam combining involves stimulated Raman scattering using a Stokes' shifted seed beam, the latter of which is optimized in terms of its temporal and spectral properties. Beams from fiber lasers can thus be combined to attain pulses with peak energies in excess of the fiber laser self-focusing limit of 4 MW while retaining the advantages of a fiber laser system of high average power with good beam quality.

  2. Bright emission lines in new Seyfert galaxies

    International Nuclear Information System (INIS)

    Afanasev, V.L.; Denisiuk, E.K.; Lipovetskii, V.A.; Shapovalova, A.I.

    1983-01-01

    Observational data are given on bright emission lines (H-alpha, H-beta, and forbidden N II, S II, and O III) for 14 recently discovered Seyfert galaxies. The investigated objects can be divided into three groups, which correspond approximately to the first (5 objects), the intermediate (4 objects), and the second (4 objects) Seyfert types. Attention is drawn to the properties of the galaxy Markaryan 1018, which has features of both the first and the second type and is distinguished by the weakness of its emission lines, which is probably due to a gas deficit. 7 references

  3. On the completeness of a sample of bright quasars selected by colour excess in the direction of the North Galactic Pole

    International Nuclear Information System (INIS)

    Warnock, A. III; Usher, P.D.

    1986-01-01

    The Medium Bright Quasar survey (MBQS) shows evidence for a dearth of bright quasars in a Palomar Schmidt field centred on Selected Area (SA) 57 near the North Galactic Pole, compared to similar fields centred on SA 28, 29, 55, and 94. The SA 57 field has been searched again for bright quasar candidates with the held of a second survey plate exposed according to a slightly modified Haro-Luyten three-colour (Tonantzintla) prescription. Candidates so selected have both a blue and ultraviolet excess (B-UVX). The main result of the paper is that there appear to be no B-UVX quasars in the SA 57 field that are brighter than B=17.25 mag. The significance of this apparent anomaly is briefly discussed. (author)

  4. Next generation diode lasers with enhanced brightness

    Science.gov (United States)

    Ried, S.; Rauch, S.; Irmler, L.; Rikels, J.; Killi, A.; Papastathopoulos, E.; Sarailou, E.; Zimer, H.

    2018-02-01

    High-power diode lasers are nowadays well established manufacturing tools in high power materials processing, mainly for tactile welding, surface treatment and cladding applications. Typical beam parameter products (BPP) of such lasers range from 30 to 50 mm·mrad at several kilowatts of output power. TRUMPF offers a product line of diode lasers to its customers ranging from 150 W up to 6 kW of output power. These diode lasers combine high reliability with small footprint and high efficiency. However, up to now these lasers are limited in brightness due to the commonly used spatial and coarse spectral beam combining techniques. Recently diode lasers with enhanced brightness have been presented by use of dense wavelength multiplexing (DWM). In this paper we report on TRUMPF's diode lasers utilizing DWM. We demonstrate a 2 kW and a 4 kW system ideally suited for fine welding and scanner welding applications. The typical laser efficiency is in the range of 50%. The system offers plug and play exchange of the fiber beam delivery cable, multiple optical outputs and integrated cooling in a very compact package. An advanced control system offers flexible integration in any customer's shop floor environment and includes industry 4.0 capabilities (e.g. condition monitoring and predictive maintenance).

  5. Brightness and transparency in the early visual cortex.

    Science.gov (United States)

    Salmela, Viljami R; Vanni, Simo

    2013-06-24

    Several psychophysical studies have shown that transparency can have drastic effects on brightness and lightness. However, the neural processes generating these effects have remained unresolved. Several lines of evidence suggest that the early visual cortex is important for brightness perception. While single cell recordings suggest that surface brightness is represented in the primary visual cortex, the results of functional magnetic resonance imaging (fMRI) studies have been discrepant. In addition, the location of the neural representation of transparency is not yet known. We investigated whether the fMRI responses in areas V1, V2, and V3 correlate with brightness and transparency. To dissociate the blood oxygen level-dependent (BOLD) response to brightness from the response to local border contrast and mean luminance, we used variants of White's brightness illusion, both opaque and transparent, in which luminance increments and decrements cancel each other out. The stimuli consisted of a target surface and a surround. The surround luminance was always sinusoidally modulated at 0.5 Hz to induce brightness modulation to the target. The target luminance was constant or modulated in counterphase to null brightness modulation. The mean signal changes were calculated from the voxels in V1, V2, and V3 corresponding to the retinotopic location of the target surface. The BOLD responses were significantly stronger for modulating brightness than for stimuli with constant brightness. In addition, the responses were stronger for transparent than for opaque stimuli, but there was more individual variation. No interaction between brightness and transparency was found. The results show that the early visual areas V1-V3 are sensitive to surface brightness and transparency and suggest that brightness and transparency are represented separately.

  6. Ultraviolet extensions of particle physics

    DEFF Research Database (Denmark)

    Berthier, Laure Gaëlle

    The discovery of the Higgs boson in 2012 at the Large Hadron Collider completed the Standard Model field content. Many questions though remain unanswered by the Standard Model triggering a search for new physics. New physics could manifest itself at the Large Hadron Collider by the discovery of new...... particles. However, the lack of new resonances might suggest that these new particles are still out of reach which leaves us with few options. Two possibilities are explored in this thesis. The first is to study precision measurements which might indicate new physics as small deviations from the Standard...... are expressed as power series with missing higher order terms. We also show how to connect ultraviolet models of new physics to the Standard Model effective field theory and calculate bounds on them using the Standard Model effective field theory fit results. Finally, we study a nonrelativistic ultraviolet...

  7. Very-High-Brightness Picosecond Electron Source

    International Nuclear Information System (INIS)

    Bluem, H.

    2003-01-01

    Bright, RF photocathode electron guns are the source of choice for most high-performance research accelerator applications. Some of these applications are pushing the performance boundaries of the present state-of-the-art guns. Advanced Energy Systems is developing a novel photocathode RF gun that shows excellent promise for extending gun performance. Initial gun simulations with only a short booster accelerator easily break the benchmark emittance of one micron for 1 nC of bunch charge. The pulse length in these simulations is less than 2 ps. It is expected that with more detailed optimization studies, the performance can be further improved. The performance details of the gun will be presented. In addition, we will discuss the present design concept along with the status of the project

  8. New redshifts of bright galaxies. III

    International Nuclear Information System (INIS)

    de Vaucouleurs, G.; de Vaucouleurs, A.; Nieto, J.

    1979-01-01

    Redshifts of 196 bright galaxies, and 2 QSO's are derived from 246 spectrograms obtained from 1972 to 1977 with the Galaxy meter's two-state image tube grism spectrograph attached at the Cassegrain focus of the McDonald Observatory Struve reflector. The reciprocal dispersion in 335 A/mm at Hα and the wavelength range lambdalambda 4500--8000 A. The galaxy redshifts are in the range -28 -1 , but few exceed 5,000 km s -1 . The internal mean errors of the weighted mean velocities range from 22 to 140 km s -1 . Comparisons with other systems of redshifts, particularly the RC2, 21-cm and Sandage systems, indicate a mean systematic error of -35 +- 16 km s -1 , but it is probably variable with V. The external mean error is sigma*=90 km s -1 for velocities V -1 having a mean weight =4.0

  9. Dark Skies, Bright Kids Year 8

    Science.gov (United States)

    Bittle, Lauren E.; Wenger, Trey; Johnson, Kelsey E.; Angell, Dylan; Burkhardt, Andrew; Davis, Blair; Firebaugh, Ariel; Hancock, Danielle; Richardson, Whitney; Rochford Hayes, Christian; Linden, Sean; Liss, Sandra; Matthews, Allison; McNair, Shunlante; Prager, Brian; Pryal, Matthew; Troup, Nicholas William

    2017-01-01

    We present activities from the eighth year of Dark Skies Bright Kids (DSBK), an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in Central Virginia through fun, hands-on activities that introduce basic Astronomy concepts. Over the past seven years, our primary focus has been hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools, and over the past several years, we have partnered with local businesses to host our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows. This past summer we expanded our reach through a new initiative to bring week-long summer day camps to south and southwest Virginia, home to some of the most underserved communities in the commonwealth.

  10. Dark Skies, Bright Kids Year 7

    Science.gov (United States)

    Bittle, Lauren E.; Johnson, Kelsey E.; Borish, H. Jacob; Burkhardt, Andrew; Firebaugh, Ariel; Hancock, Danielle; Rochford Hayes, Christian; Linden, Sean; Liss, Sandra; Matthews, Allison; Prager, Brian; Pryal, Matthew; Sokal, Kimberly R.; Troup, Nicholas William; Wenger, Trey

    2016-01-01

    We present updates from our seventh year of operation including new club content, continued assessments, and our fifth annual Star Party. Dark Skies, Bright Kids (DSBK) is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in Central Virginia through fun, hands-on activities that introduce basic Astronomy concepts. Our primary focus is hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools. Each week, DSBK volunteers take the role of coaches to introduce astronomy-related concepts ranging from the Solar System to galaxies to astrobiology, and to lead students in interactive learning activities. Another hallmark of DSBK is hosting our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows.

  11. Considerations for high-brightness electron sources

    International Nuclear Information System (INIS)

    Jameson, R.A.

    1990-01-01

    Particle accelerators are now used in many areas of physics research and in industrial and medical applications. New uses are being studied to address major societal needs in energy production, materials research, generation of intense beams of radiation at optical and suboptical wavelengths, treatment of various kinds of waste, and so on. Many of these modern applications require a high intensity beam at the desired energy, along with a very good beam quality in terms of the beam confinement, aiming, or focusing. Considerations for ion and electron accelerators are often different, but there are also many commonalties, and in fact, techniques derived for one should perhaps more often be considered for the other as well. We discuss some aspects of high-brightness electron sources here from that point of view. 6 refs

  12. Metal luminescence in a bright disintegrated prominence

    International Nuclear Information System (INIS)

    Yakovkin, N.A.; Zel'dina, M.Yu.; Rakhubovskij, A.S.; AN Ukrainskoj SSR, Kiev. Glavnaya Astronomicheskaya Observatoriya)

    1975-01-01

    It is found that Na, Mg, Ca, Sc, Ti, Fe, Sr, and Ba contents in a protuberance relative to the hydrogen content is about the same as in photosphere and chromosphere (except for the Na abundance). The metals are in the state of single ionization with the exception of calcium [Ca ++ ] approximately [Ca + ], strontium [Sr ++ ] = 0.5 [Sr + ], and barium [Ba ++ ] = 6Ba + , whose secondary ionization occurs from metastable states by Lsub(α)-emission in the protuberance. The Lsub(α)-emission ionizes neutral iron as well. Primary ionization of remaining metals is performed by the solar near ultraviolet. Luminescence in metal lines is provided by the photosphere emission scattering, and only H and KCa + lines are excited by electron impacts

  13. Life-threatening motor vehicle crashes in bright sunlight

    OpenAIRE

    Redelmeier, Donald A.; Raza, Sheharyar

    2017-01-01

    Abstract Bright sunlight may create visual illusions that lead to driver error, including fallible distance judgment from aerial perspective. We tested whether the risk of a life-threatening motor vehicle crash was increased when driving in bright sunlight. This longitudinal, case-only, paired-comparison analysis evaluated patients hospitalized because of a motor vehicle crash between January 1, 1995 and December 31, 2014. The relative risk of a crash associated with bright sunlight was estim...

  14. Development of Yellow Sand Image Products Using Infrared Brightness Temperature Difference Method

    Science.gov (United States)

    Ha, J.; Kim, J.; Kwak, M.; Ha, K.

    2007-12-01

    A technique for detection of airborne yellow sand dust using meteorological satellite has been developed from various bands from ultraviolet to infrared channels. Among them, Infrared (IR) channels have an advantage of detecting aerosols over high reflecting surface as well as during nighttime. There had been suggestion of using brightness temperature difference (BTD) between 11 and 12¥ìm. We have found that the technique is highly depends on surface temperature, emissivity, and zenith angle, which results in changing the threshold of BTD. In order to overcome these problems, we have constructed the background brightness temperature threshold of BTD and then aerosol index (AI) has been determined from subtracting the background threshold from BTD of our interested scene. Along with this, we utilized high temporal coverage of geostationary satellite, MTSAT, to improve the reliability of the determined AI signal. The products have been evaluated by comparing the forecasted wind field with the movement fiend of AI. The statistical score test illustrates that this newly developed algorithm produces a promising result for detecting mineral dust by reducing the errors with respect to the current BTD method.

  15. High-brightness high-order harmonic generation at 13 nm with a long gas jet

    International Nuclear Information System (INIS)

    Kim, Hyung Taek; Kim, I Jong; Lee, Dong Gun; Park, Jong Ju; Hong, Kyung Han; Nam, Chang Hee

    2002-01-01

    The generation of high-order harmonics is well-known method producing coherent extreme-ultraviolet radiation with pulse duration in the femtosecond regime. High-order harmonics have attracted much attention due to their unique features such as coherence, ultrashort pulse duration, and table-top scale system. Due to these unique properties, high-order harmonics have many applications of atomic and molecular spectroscopy, plasma diagnostics and solid-state physics. Bright generation of high-order harmonics is important for actual applications. Especially, the generation of strong well-collimated harmonics at 13 nm can be useful for the metrology of EUV lithography optics because of the high reflectivity of Mo-Si mirrors at this wavelength. The generation of bright high-order harmonics is rather difficult in the wavelength region below 15nm. Though argon and xenon gases have large conversion efficiency, harmonic generation from these gases is restricted to wavelengths over 20 nm due to low ionization potential. Hence, we choose neon for the harmonic generation around 13 nm; it has larger conversion efficiency than helium and higher ionization potential than argon. In this experiment, we have observed enhanced harmonic generation efficiency and low beam divergence of high-order harmonics from a elongated neon gas jet by the enhancement of laser propagation in an elongated gas jet. A uniform plasma column was produced when the gas jet was exposed to converging laser pulses.

  16. IRAS surface brightness maps of visible reflection nebulae: evidence for non-equilibrium infrared emission

    International Nuclear Information System (INIS)

    Castelaz, M.W.; Werner, M.W.; Sellgren, K.

    1986-01-01

    Surface brightness maps at 12, 25, 60, and 100 microns of 16 visible reflection nebulae were extracted from the Infrared Astronomy Satellite (IRAS) database. The maps were produced by coadding IRAS survey scans over areas centered on the illuminating stars, and have spatial resolutions of 0.9' x 4' at 12 and 25 microns, 1.8' x 4.5' at 60 microns, and 3.6' x 5' at 100 microns. Extended emission in the four IRAS bandpasses was detected in fourteen of the reflection nebulae. The IRAS data were used to measure the flux of the infrared emission associated with each source. The energy distributions show that the 12 micron flux is greater than the 25 micron flux in 11 of the nebulae, and the peak flux occurs in the 60 or 100 micron bandpass in all 16 nebular. The 60 and 100 micron flux can be approximated by blackbodies with temperatures between 30 and 50 K, consistent with temperatures expected from extrapolation of greybody fits to the 60 and 100 micron data. The excess 12 and 25 micron emission is attributed to a nonequilibrium process such as emission from thermal fluctuations of very small grains excited by single ultraviolet photons, or emission from polycyclic aromatic hydrocarbons (PAHs) excited by ultraviolet radiation. The common features of the energy distributions of the 16 reflection nebulae, also seen in the reflection nebulae associated with the Pleiades, suggest that PAHs or very small grains may be found in most reflection nebulae

  17. Study of Three-Dimensional Image Brightness Loss in Stereoscopy

    Directory of Open Access Journals (Sweden)

    Hsing-Cheng Yu

    2015-10-01

    Full Text Available When viewing three-dimensional (3D images, whether in cinemas or on stereoscopic televisions, viewers experience the same problem of image brightness loss. This study aims to investigate image brightness loss in 3D displays, with the primary aim being to quantify the image brightness degradation in the 3D mode. A further aim is to determine the image brightness relationship to the corresponding two-dimensional (2D images in order to adjust the 3D-image brightness values. In addition, the photographic principle is used in this study to measure metering values by capturing 2D and 3D images on television screens. By analyzing these images with statistical product and service solutions (SPSS software, the image brightness values can be estimated using the statistical regression model, which can also indicate the impact of various environmental factors or hardware on the image brightness. In analysis of the experimental results, comparison of the image brightness between 2D and 3D images indicates 60.8% degradation in the 3D image brightness amplitude. The experimental values, from 52.4% to 69.2%, are within the 95% confidence interval

  18. The night sky brightness at McDonald Observatory

    Science.gov (United States)

    Kalinowski, J. K.; Roosen, R. G.; Brandt, J. C.

    1975-01-01

    Baseline observations of the night sky brightness in B and V are presented for McDonald Observatory. In agreement with earlier work by Elvey and Rudnick (1937) and Elvey (1943), significant night-to-night and same-night variations in sky brightness are found. Possible causes for these variations are discussed. The largest variation in sky brightness found during a single night is approximately a factor of two, a value which corresponds to a factor-of-four variation in airglow brightness. The data are used to comment on the accuracy of previously published surface photometry of M 81.

  19. VizieR Online Data Catalog: UV-bright quasars (Syphers+, 2009)

    Science.gov (United States)

    Syphers, D.; Anderson, S. F.; Zheng, W.; Haggard, D.; Meiksin, A.; Schneider, D. P.; York, D. G.

    2010-03-01

    Absorption along quasar sightlines remains among the most sensitive direct measures of HeII reionization in much of the intergalactic medium (IGM). Until recently, fewer than a half-dozen unobscured quasar sightlines suitable for the HeII Gunn-Peterson test were known; although these handful demonstrated great promise, the small sample size limited confidence in cosmological inferences. We have recently added nine more such clean HeII quasars, exploiting Sloan Digital Sky Survey (SDSS) quasar samples, broadband ultraviolet (UV) imaging from Galaxy Evolution Explorer (GALEX), and high-yield UV spectroscopic confirmations from Hubble Space Telescope (HST). Here we markedly expand this approach by cross-correlating SDSS DR7 and GALEX GR4+5 to catalog 428 SDSS and 165 other quasars with z>2.78 having likely (~70%) GALEX detections, suggesting they are bright into the far-UV. Reconnaissance HST Cycle 16 Supplemental prism data for 29 of these new quasar-GALEX matches spectroscopically confirm 17 as indeed far-UV bright. At least 10 of these confirmations have clean sightlines all the way down to HeII Lyα, substantially expanding the number of known clean HeII quasars, and reaffirming the order of magnitude enhanced efficiency of our selection technique. Combined confirmations from this and our past programs yield more than 20 HeII quasars, quintupling the sample. These provide substantial progress toward a sample of HeII quasar sightlines large enough, and spanning a sufficient redshift range, to enable statistical IGM studies that may avoid individual object peculiarity and sightline variance. Our expanded catalog of hundreds of high-likelihood far-UV-bright QSOs additionally will be useful for understanding the extreme-UV properties of the quasars themselves. (2 data files).

  20. NO TIME FOR DEAD TIME: TIMING ANALYSIS OF BRIGHT BLACK HOLE BINARIES WITH NuSTAR

    Energy Technology Data Exchange (ETDEWEB)

    Bachetti, Matteo; Barret, Didier [Université de Toulouse, UPS-OMP, IRAP, Toulouse F-31400 (France); Harrison, Fiona A.; Cook, Rick; Grefenstette, Brian W.; Fürst, Felix [Cahill Center for Astronomy and Astrophysics, Caltech, Pasadena, CA 91125 (United States); Tomsick, John; Boggs, Steven E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Schmid, Christian [Dr. Karl-Remeis-Sternwarte and ECAP, Sternwartstrasse 7, D-96049 Bamberg (Germany); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Fabian, Andrew C.; Kara, Erin [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Gandhi, Poshak [Department of Physics, Durham University, South Road DH1 3LE (United Kingdom); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Maccarone, Thomas J. [Department of Physics, Texas Tech University, Lubbock, TX 79409 (United States); Miller, Jon M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Pottschmidt, Katja [CRESST, UMBC, and NASA GSFC, Code 661, Greenbelt, MD 20771 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Uttley, Phil, E-mail: matteo.bachetti@irap.omp.eu [Anton Pannekoek Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); and others

    2015-02-20

    Timing of high-count-rate sources with the NuSTAR Small Explorer Mission requires specialized analysis techniques. NuSTAR was primarily designed for spectroscopic observations of sources with relatively low count rates rather than for timing analysis of bright objects. The instrumental dead time per event is relatively long (∼2.5 msec) and varies event-to-event by a few percent. The most obvious effect is a distortion of the white noise level in the power density spectrum (PDS) that cannot be easily modeled with standard techniques due to the variable nature of the dead time. In this paper, we show that it is possible to exploit the presence of two completely independent focal planes and use the cospectrum, the real part of the cross PDS, to obtain a good proxy of the white-noise-subtracted PDS. Thereafter, one can use a Monte Carlo approach to estimate the remaining effects of dead time, namely, a frequency-dependent modulation of the variance and a frequency-independent drop of the sensitivity to variability. In this way, most of the standard timing analysis can be performed, albeit with a sacrifice in signal-to-noise ratio relative to what would be achieved using more standard techniques. We apply this technique to NuSTAR observations of the black hole binaries GX 339–4, Cyg X-1, and GRS 1915+105.

  1. Skylab ultraviolet stellar spectra - A new white dwarf, HD 149499 B

    Science.gov (United States)

    Parsons, S. B.; Wray, J. D.; Benedict, G. F.; Henize, K. G.; Laget, M.

    1976-01-01

    The letter reports the discovery of a cool star with excess brightness in the vacuum ultraviolet on an objective-prism photograph obtained during the second Skylab mission. This star, HD 149499, is of type K0 V and has a companion with an apparent magnitude of about 11.8; the relatively flat UV spectrum observed at the position of HD 149499 is characteristic of a 10th or 11th magnitude unreddened O- or early B-type star. It is shown that the excess VUV brightness is due to the companion, HD 149499B, which probably lies in the region of the H-R diagram occupied by the hot white dwarfs. Inspection of white dwarf lists indicates that this star is the sixth or seventh brightest white dwarf known. A maximum orbital motion of 0.025 arcsec/yr is estimated along with a period of just under 500 yr.

  2. ORIGIN OF THE DIFFUSE, FAR ULTRAVIOLET EMISSION IN THE INTERARM REGIONS OF M101

    International Nuclear Information System (INIS)

    Crocker, Alison F.; Chandar, Rupali; Calzetti, Daniela; Holwerda, Benne Willem; Leitherer, Claus; Popescu, Cristina; Tuffs, R. J.

    2015-01-01

    We present images from the Solar Blind Channel on the Hubble Space Telescope that resolve hundreds of far-ultraviolet (FUV) emitting stars in two ∼1 kpc 2 interarm regions of the grand-design spiral M101. The luminosity functions of these stars are compared with predicted distributions from simple star formation histories, and are best reproduced when the star formation rate has recently declined (past 10–50 Myr). This pattern is consistent with stars forming within spiral arms and then streaming into the interarm regions. We measure the diffuse FUV surface brightness after subtracting all of the detected stars, clusters, and background galaxies. A residual flux is found for both regions, which can be explained by a mix of stars below our detection limit and scattered FUV light. The amount of scattered light required is much larger for the region immediately adjacent to a spiral arm, a bright source of FUV photons

  3. The ultraviolet to X-ray continua of BL Lac objects

    International Nuclear Information System (INIS)

    George, I.M.; Warwick, R.S.; McHardy, I.M.

    1988-01-01

    The results from EXOSAT observations of three X-ray bright BL Lacertae objects, Mrk 501, 1218 + 304 and Mrk 180 are presented. All three sources have soft power-law X-ray spectra with low-energy cut-offs consistent with absorption in the line-of-sight gas column density through our own galaxy. The three objects also exhibit significant spectral variability in the X-ray band on time-scales ranging from a few days to a year. In each case, X-ray flux and spectral index appear to be correlated, in the sense that the X-ray spectrum hardens as the source brightens. The intrinsic ultraviolet to X-ray spectrum of these and several other X-ray bright BL Lac objects can be modelled as a power-law continuum of energy index ∼1.0 below about 0.1 keV, above which the spectral slope steepens. (author)

  4. Dosimetry of ultraviolet radiation with BaHfO_3 powders

    International Nuclear Information System (INIS)

    Barrera A, A. A.; Aguilar D, G. A.; Guzman M, J.; Rivera M, T.; Ceron R, V.

    2016-10-01

    Ceramic materials based on pure barium hafnate (BaHfO_3) have been obtained as a powder by the co-precipitation method. The powders obtained have a cubic structure that favors the thermoluminescent and optical properties, through which a better detection of the non-ionizing radiation is allowed. With these powders various tests were performed in the ultraviolet range at different exposure times. These thermoluminescent (Tl) studies were carried out using a Tl 3500 hand held reader which yielded a brightness curve that ranged from room temperature to the 350 degrees Celsius. This BaHfO_3 response exhibits a broad brightness curve with a single peak centered around 225 degrees Celsius. Finally, is reported that there are materials of barium hafnate (BaHfO_3) doped with some rare earths (Eu, Tb) which, instead of improving the performance of the powders, decrease it, so that the use of intrinsic barium hafnate is the most appropriate. (Author)

  5. Large-solid-angle illuminators for extreme ultraviolet lithography with laser plasmas

    International Nuclear Information System (INIS)

    Kubiak, G.D.; Tichenor, D.A.; Sweatt, W.C.; Chow, W.W.

    1995-06-01

    Laser Plasma Sources (LPSS) of extreme ultraviolet radiation are an attractive alternative to synchrotron radiation sources for extreme ultraviolet lithography (EUVL) due to their modularity, brightness, and modest size and cost. To fully exploit the extreme ultraviolet power emitted by such sources, it is necessary to capture the largest possible fraction of the source emission half-sphere while simultaneously optimizing the illumination stationarity and uniformity on the object mask. In this LDRD project, laser plasma source illumination systems for EUVL have been designed and then theoretically and experimentally characterized. Ellipsoidal condensers have been found to be simple yet extremely efficient condensers for small-field EUVL imaging systems. The effects of aberrations in such condensers on extreme ultraviolet (EUV) imaging have been studied with physical optics modeling. Lastly, the design of an efficient large-solid-angle condenser has been completed. It collects 50% of the available laser plasma source power at 14 nm and delivers it properly to the object mask in a wide-arc-field camera

  6. Bright environments vision of the Intelligent Lighting Institute (ILI)

    NARCIS (Netherlands)

    Özçelebi, T.

    2014-01-01

    The Bright Environments research program of the Eindhoven University of Technology Intelligent Lighting Institute aims to find new methods of intelligent lighting control and human interaction. We present a summary of the institute’s work on this research field and the research vision of the Bright

  7. Spatially single-mode source of bright squeezed vacuum

    OpenAIRE

    Pérez, A. M.; Iskhakov, T. Sh.; Sharapova, P.; Lemieux, S.; Tikhonova, O. V.; Chekhova, M. V.; Leuchs, G.

    2014-01-01

    Bright squeezed vacuum, a macroscopic nonclassical state of light, can be obtained at the output of a strongly pumped non-seeded traveling-wave optical parametric amplifier (OPA). By constructing the OPA of two consecutive crystals separated by a large distance we make the squeezed vacuum spatially single-mode without a significant decrease in the brightness or squeezing.

  8. The ASAS-SN bright supernova catalogue - III. 2016

    DEFF Research Database (Denmark)

    Holoien, T. W. -S.; Brown, J. S.; Stanek, K. Z.

    2017-01-01

    This catalogue summarizes information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) and all other bright (m(peak)d......This catalogue summarizes information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) and all other bright (m(peak)d...

  9. Analysis of Bright Harvest Remote Analysis for Residential Solar Installations

    Energy Technology Data Exchange (ETDEWEB)

    Nangle, John [National Renewable Energy Lab. (NREL), Golden, CO (United States); Simon, Joseph [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-06-17

    Bright Harvest provides remote shading analysis and design products for residential PV system installers. The National Renewable Energy Laboratory (NREL) through the NREL Commercialization Assistance Program, completed comparative assessments between on-site measurements and remotely calculated values to validate the accuracy of Bright Harvest’s remote shading and power generation.

  10. Dark and bright vortex solitons in electromagnetically induced transparent media

    International Nuclear Information System (INIS)

    Wu Xuan; Xie Xiaotao; Yang Xiaoxue

    2006-01-01

    We show that dark and bright vortex solitons can exist in three-state electromagnetically induced transparent media under some appropriate conditions. We also analyse the stability of the dark and bright vortex solitons. This work may provide other research opportunities in nonlinear optical experiments and may result in a substantial impact on technology

  11. Edge integration and the perception of brightness and darkness

    NARCIS (Netherlands)

    Vladusich, T.; Lucassen, M.P.; Cornelissen, F.W.

    2006-01-01

    How do induced brightness and darkness signals from local and remote surfaces interact to determine the final achromatic color percept of a target surface? An emerging theory of achromatic color perception posits that brightness and darkness percepts are computed by weighting and summing the

  12. Lamp spectrum and spatial brightness at photopic levels

    DEFF Research Database (Denmark)

    Fotios, Steve; Atli, Deniz; Cheal, Chris

    2015-01-01

    Light sources are available in a variety of spectral power distributions (SPDs) and this affects spatial brightness in a manner not predicted by quantities such as illuminance. Tuning light source SPD to better match the sensitivity of visual perception may allow the same spatial brightness but a...

  13. Ultraviolet divergences and supersymmetric theories

    International Nuclear Information System (INIS)

    Sagnotti, A.

    1984-09-01

    This article is closely related to the one by Ferrara in these same Proceedings. It deals with what is perhaps the most fascinating property of supersymmetric theories, their improved ultraviolet behavior. My aim here is to present a survey of the state of the art as of August, 1984, and a somewhat more detailed discussion of the breakdown of the superspace power-counting beyond N = 2 superfields. A method is also described for simplifying divergence calculations that uses the locality of subtracted Feynman integrals. 74 references

  14. Ultraviolet disinfection of potable water

    Energy Technology Data Exchange (ETDEWEB)

    Wolfe, R. L. [Metropolitan Water District of Southern California, Los Angeles, CA (United States)

    1990-06-15

    Because of upcoming surface and groundwater regulations regarding the control of microbiological and chemical contaminants, there is a need to evaluate the feasibility and effectiveness of ultraviolet (UV) radiation for primary disinfection of potable water supplies. Data is presented on microbicidal wavelengths of UV and distribution of energy output for low and medium-pressure arc lamps. Both systems were found to perform equally well for inactivating microorganisms, but each had distinct advantages in different applications. Approximate dosages for 90% inactivation of selected microorganisms by UV is presented in a table. Cost analysis for disinfection is presented in two tables as well as the advantages and disadvantages of UV disinfection.

  15. Ultraviolet disinfection of potable water

    International Nuclear Information System (INIS)

    Wolfe, R.L.

    1990-01-01

    Because of upcoming surface and groundwater regulations regarding the control of microbiological and chemical contaminants, there is a need to evaluate the feasibility and effectiveness of ultraviolet (UV) radiation for primary disinfection of potable water supplies. Data is presented on microbicidal wavelengths of UV and distribution of energy output for low and medium-pressure arc lamps. Both systems were found to perform equally well for inactivating microorganisms, but each had distinct advantages in different applications. Approximate dosages for 90% inactivation of selected microorganisms by UV is presented in a table. Cost analysis for disinfection is presented in two tables as well as the advantages and disadvantages of UV disinfection

  16. Ultraviolet divergences of Einstein gravity

    International Nuclear Information System (INIS)

    Goroff, M.H.

    1986-01-01

    The author discuss a two-loop calculation showing that the S matrix of Einstein's theory of gravity contains nonrenormalizable ultraviolet divergences in four dimension. The author discusses the calculation in both background field and normal field theory. The author describes a new method for dealing with ghost fields in gauge theories by combining them with suitable extensions of the gauge fields in higher dimensions. The author shows how using subtracted integrals in the calculation of higher loop graphs simplifies the calculation in the background field method by eliminating the need for mixed counterterms. Finally, the author makes some remarks about the implications of the result for supergravity theories

  17. Ultraviolet laser technology and applications

    CERN Document Server

    Elliott, David L

    1995-01-01

    Ultraviolet Laser Technology and Applications is a hands-on reference text that identifies the main areas of UV laser technology; describes how each is applied; offers clearly illustrated examples of UV opticalsystems applications; and includes technical data on optics, lasers, materials, and systems. This book is unique for its comprehensive, in-depth coverage. Each chapter deals with a different aspect of the subject, beginning with UV light itself; moving through the optics, sources, and systems; and concluding with detailed descriptions of applications in various fields.The text enables pr

  18. Brightness waves of electroluminescence in ZnO:La electroluminor

    International Nuclear Information System (INIS)

    Bhushan, S.; Pandey, A.N.; Kaza, Balakrishna Rao

    1979-01-01

    A cryostat for the measurement of different luminescent characteristics from liquid N 2 temperature to above has been fabricated. Using this cryostat brightness waves due to sinusoidal excitations for ZnO:La electroluminor (EL) has been studied at different temperatures from -168deg C. Brightness waves for this system consist of two primary peaks during each cycle of excitation. Each primary peak is associated with a secondary peak. This secondary peak at -168deg C exists at the left arm of the primary peak. As the temperature is increased to 18deg C it moves towards the right arm of the primary peak. At an intermediate temperature the secondary peaks are most pronounced. Possible mechanism for these phenomena have been discussed. Temperature dependence of time averaged EL brightness for this system has also been studied and three peaks have been found. The results of brightness waves have also been discussed in the light of temperature dependence of time averaged EL brightness. (auth.)

  19. Intrinsic brightness temperatures of blazar jets at 15 GHz

    Directory of Open Access Journals (Sweden)

    Hovatta Talvikki

    2013-12-01

    Full Text Available We have developed a new Bayesian Markov Chain Monte Carlo method to deconvolve light curves of blazars into individual flares, including proper estimation of the fit errors. We use the method to fit 15GHzlight curves obtained within the OVRO 40-m blazar monitoring program where a large number of AGN have been monitored since 2008 in support of the Fermi Gamma-Ray Space Telescope mission. The time scales obtained from the fitted models are used to calculate the variability brightness temperature of the sources. Additionally, we have calculated brightness temperatures of a sample of these objects using Very Long Baseline Array data from the MOJAVE survey. Combining these two data sets enables us to study the intrinsic brightness temperature distribution in these blazars at 15 GHz. Our preliminary results indicate that the mean intrinsic brightness temperature in a sample of 14 sources is near the equipartition brightness temperature of ~ 1011K.

  20. Intercomparisons of nine sky brightness detectors.

    Science.gov (United States)

    den Outer, Peter; Lolkema, Dorien; Haaima, Marty; van der Hoff, Rene; Spoelstra, Henk; Schmidt, Wim

    2011-01-01

    Nine Sky Quality Meters (SQMs) have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across The Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from -16% to +20%. Intercalibration reduces this to 0.5%, and -7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m(2) on 12 April, and the largest value was 5.94 ± 0.03 mcd/m(2) on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.

  1. Dark Skies, Bright Kids Year 9

    Science.gov (United States)

    Burkhardt, Andrew Michael; Matthews, Allison M.; Johnson, Kelsey E.; Avilez, Ian; Beale, Luca; Bittle, Lauren E.; Bordenave, David; Finn, Molly; Firebaugh, Ariel; Hancock, Danielle; Hughes, Paul; Rochford Hayes, Christian; Lewis, Hannah; Linden, Sean; Liss, Sandra; Liu, Mengyao; McNair, Shunlante; Murphy, Edward; Prager, Brian; Pryal, Matthew; Richardson, Whitney; Song, Yiqing; Troup, Nicholas; Villadsen, Jackie; Wenger, Trey V.; Wilson, Robert Forrest

    2018-01-01

    We present updates from the ninth year of operation of Dark Skies, Bright Kids (DSBK) including new club content, continued assessments, and our seventh annual Star Party. DSBK is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in Virginia through fun, hands-on activities that introduce basic Astronomy concepts. DSBK’s most fundamental program is an 8-10 week long after-school Astronomy camp at surrounding local elementary schools, where each week introduces new concepts through interactive hands-on activities. Over the past two summers, we have traveled to four rural Virginia locations to bring week-long Astronomy camps to otherwise overlooked elementary school districts. These programs aim to inspire a curiosity for science and include inquiry based activities in topics ranging from the electromagnetic spectrum to the classification and evolution of galaxies. We strive to be self-reflective in our mission to inspire scientific curiosity in the minds of underserved demographics. In this effort, we continually assess the effectiveness of each activity through feedback in student-kept journal pages and observed excitement levels. This self-reflection has initiated the development of new curriculum. In addition, differing from our normal collaboration with local elementary schools, we have found great success partnering with local youth organizations, who may better represent DSBK's target demographics and have infrastructure to support incoming outreach groups.

  2. Enhanced brightness x-ray lasers

    International Nuclear Information System (INIS)

    Wan, A.S.; Cauble, R.C.; Da Silva, L.B.; Moreno, J.C.; Nilsen, J.

    1994-09-01

    We are developing short-pulsed, enhanced-brightness, and coherent x-ray lasers (XRLs) for applications in areas such as plasma imaging. In a traveling wave pump setup the optical laser creating the XRL plasma sweeps along the lasant axis at the same speed as the x-rays. This technique becomes increasingly important as the target length increases and the gain duration shortens. An order of magnitude increase in output energy was measured with vs without traveling wave pump. Using multiple pulse techniques and multilayer mirrors to inject the output of one pulse back into the plasma formed by a later pulse we have begun to develop the x-ray analog of a multi-pass amplifler. The use of multiple pulses separated by as much as 1.6 ns reduces multilayer mirror damage. This injection technique is demonstrated by imaging the near-field emission profiles of the XRL. The addition of multilayer beamsplitter will allow us to effectively produce a soft XRL cavity

  3. Featured Image: Bright Dots in a Sunspot

    Science.gov (United States)

    Kohler, Susanna

    2018-03-01

    This image of a sunspot, located in in NOAA AR 12227, was captured in December 2014 by the 0.5-meter Solar Optical Telescope on board the Hinode spacecraft. This image was processed by a team of scientists led by Rahul Yadav (Udaipur Solar Observatory, Physical Research Laboratory Dewali, India) in order to examine the properties of umbral dots: transient, bright features observed in the umbral region (the central, darkest part) of a sunspot. By exploring these dots, Yadav and collaborators learned how their properties relate to the large-scale properties of the sunspots in which they form for instance, how do the number, intensities, or filling factors of dots relate to the size of a sunspots umbra? To find out more about the authors results, check out the article below.Sunspot in NOAA AR 11921. Left: umbralpenumbral boundary. Center: the isolated umbra from the sunspot. Right: The umbra with locations of umbral dots indicated by yellow plus signs. [Adapted from Yadav et al. 2018]CitationRahul Yadav et al 2018 ApJ 855 8. doi:10.3847/1538-4357/aaaeba

  4. The Los Alamos high-brightness photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    O' Shea, P.G.

    1991-01-01

    For a number of years Los Alamos National Laboratory has been developing photocathode RF guns for high-brightness electron beam applications such as free-electron lasers (FELs). Previously thermionic high-voltage guns have been the source of choice for the electron accelerators used to drive FELs. The performance of such FELs is severely limited by the emittance growth produced by the subharmonic bunching process and also by the low peak current of the source. In a photoinjector, a laser driven photocathode is placed directly in a high-gradient RF accelerating cavity. A photocathode allows unsurpassed control over the current, and the spatial and temporal profile of the beam. In addition the electrodeless emission'' avoids many of the difficulties associated with multi-electrode guns, i.e. the electrons are accelerated very rapidly to relativistic energies, and there are no electrodes to distort the accelerating fields. For the past two years we have been integrating a photocathode into our existing FEL facility by replacing our thermionic gun and subharmonic bunchers with a high-gradient 1.3 GHz photoinjector. The photoinjector, which is approximately 0.6 m in length, produces 6 MeV, 300 A, 15 ps linac, and accelerated to a final energy of 40 MeV. We have recently begun lasing at wavelengths near 3 {mu}m. 16 refs., 2 figs., 5 tabs.

  5. Modular Zero Energy. BrightBuilt Home

    Energy Technology Data Exchange (ETDEWEB)

    Aldrich, Robb [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States). Steven Winters Associates, Inc.; Butterfield, Karla [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States). Steven Winters Associates, Inc.

    2016-03-01

    Kaplan Thompson Architects (KTA) has specialized in sustainable, energy-efficient buildings, and they have designed several custom, zero-energy homes in New England. These zero-energy projects have generally been high-end, custom homes with budgets that could accommodate advanced energy systems. In an attempt to make zero energy homes more affordable and accessible to a larger demographic, KTA explored modular construction as way to provide high-quality homes at lower costs. In the mid-2013, KTA formalized this concept when they launched BrightBuilt Home (BBH). The BBH mission is to offer a line of architect-designed, high-performance homes that are priced to offer substantial savings off the lifetime cost of a typical home and can be delivered in less time. For the past two years, CARB has worked with BBH and Keiser Homes (the primary modular manufacturer for BBH) to discuss challenges related to wall systems, HVAC, and quality control. In Spring of 2014, CARB and BBH began looking in detail on a home to be built in Lincolnville, ME by Black Bros. Builders. This report details the solution package specified for this modular plan and the challenges that arose during the project.

  6. Intercomparisons of Nine Sky Brightness Detectors

    Directory of Open Access Journals (Sweden)

    Henk Spoelstra

    2011-10-01

    Full Text Available Nine Sky Quality Meters (SQMs have been intercompared during a night time measurement campaign held in the Netherlands in April 2011. Since then the nine SQMs have been distributed across the Netherlands and form the Dutch network for monitoring night sky brightness. The goal of the intercomparison was to infer mutual calibration factors and obtain insight into the variability of the SQMs under different meteorological situations. An ensemble average is built from the individual measurements and used as a reference to infer the mutual calibration factors. Data required additional synchronization prior to the calibration determination, because the effect of moving clouds combined with small misalignments emerges as time jitter in the measurements. Initial scatter of the individual instruments lies between ±14%. Individual night time sums range from −16% to +20%. Intercalibration reduces this to 0.5%, and −7% to +9%, respectively. During the campaign the smallest luminance measured was 0.657 ± 0.003 mcd/m2 on 12 April, and the largest value was 5.94 ± 0.03 mcd/m2 on 2 April. During both occurrences interfering circumstances like snow cover or moonlight were absent.

  7. Dark Skies, Bright Kids Year 6

    Science.gov (United States)

    Liss, Sandra; Troup, Nicholas William; Johnson, Kelsey E.; Barcos-Munoz, Loreto D.; Beaton, Rachael; Bittle, Lauren; Borish, Henry J.; Burkhardt, Andrew; Corby, Joanna; Dean, Janice; Hancock, Danielle; King, Jennie; Prager, Brian; Romero, Charles; Sokal, Kimberly R.; Stierwalt, Sabrina; Wenger, Trey; Zucker, Catherine

    2015-01-01

    Now entering our sixth year of operation, Dark Skies, Bright Kids (DSBK) is an entirely volunteer-run outreach organization based out of the Department of Astronomy at the University of Virginia. Our core mission is to enhance elementary science education and literacy in central Virginia through fun, hands-on activities that introduce basic Astronomy concepts beyond Virginia's Standards of Learning. Our primary focus is hosting an 8-10 week after-school astronomy club at underserved elementary and middle schools. Each week, DSBK volunteers take the role of coaches to introduce astronomy-related concepts ranging from the Solar System to galaxies to astrobiology, and to lead students in interactive learning activities. Another hallmark of DSBK is hosting our Annual Central Virginia Star Party, a free event open to the community featuring star-gazing and planetarium shows.DSBK has amassed over 15,000 contact hours since 2009 and we continue to broaden our impact. One important step we have taken in the past year is to establish a graduate student led assessment program to identify and implement directed learning goals for DSBK outreach. The collection of student workbooks, observations, and volunteer surveys indicates broad scale success for the program both in terms of student learning and their perception of science. The data also reveal opportunities to improve our organizational and educational practices to maximize student achievement and overall volunteer satisfaction for DSBK's future clubs and outreach endeavors.

  8. Ultraviolet spectra of planetary nebulae

    International Nuclear Information System (INIS)

    Harrington, J.P.; Seaton, M.J.; Adams, S.; Lutz, J.H.

    1982-01-01

    A detailed study of NGC 7662 is based on UV results obtained from 15 IUE spectra and on observations of other workers at optical, IR and radio wavelengths. Improved techniques are used to extract IUE data for an extended source. Relative fluxes in the different apertures which have been used are obtained using the brightness contours of Coleman, Reay and Worswick. There is close agreement between the reddening deduced from the ratios He II (lambda 1640)/(lambda 4686) and (radio)/(Hβ) and the nebular continuum emission observed with the IUE large slots agrees closely with that predicted using absolute radio and Hβ fluxes. The fluxes in nebular emission lines observed with the small slots are smaller than expected from brightness distributions; it is concluded that, for an extended source, the small slots have aperture transmission factors of 0.85 for SWP and 0.46 for LWR. The central star is fainter than has been previously supposed (by more than two magnitudes). The blackbody He II Zanstra temperature of 113 000 K is consistent with the UV colour temperature. Previous work on colour temperatures of central stars is discussed critically. Two models are discussed. (author)

  9. Dose modeling in ultraviolet phototherapy

    International Nuclear Information System (INIS)

    Grimes, David Robert; Robbins, Chris; O'Hare, Neil John

    2010-01-01

    Purpose: Ultraviolet phototherapy is widely used in the treatment of numerous skin conditions. This treatment is well established and largely beneficial to patients on both physical and psychological levels; however, overexposure to ultraviolet radiation (UVR) can have detrimental effects, such as erythemal responses and ocular damage in addition to the potentially carcinogenic nature of UVR. For these reasons, it is essential to control and quantify the radiation dose incident upon the patient to ensure that it is both biologically effective and has the minimal possible impact on the surrounding unaffected tissue. Methods: To date, there has been little work on dose modeling, and the output of artificial UVR sources is an area where research has been recommended. This work characterizes these sources by formalizing an approach from first principles and experimentally examining this model. Results: An implementation of a line source model is found to give impressive accuracy and quantifies the output radiation well. Conclusions: This method could potentially serve as a basis for a full computational dose model for quantifying patient dose.

  10. Evolution of solar ultraviolet luminosity

    International Nuclear Information System (INIS)

    Zahnle, K.J.; Walker, J.C.G.

    1982-01-01

    In view of the major role of the sun in defining the properties of planetary atmospheres, their evolution cannot be fully understood outside the context of an evolving sun. The ultraviolet radiation is especially interesting because of its strong interaction with planetary atmospheres. We use astronomical observation of stars that are analogous to the sun in order to reconstruct a tentative account of the evolution of solar UV luminosity. A wealth of evidence indicates that the young sun was a much more powerful source of energetic particles and radiation than it is today. While on the main sequence, solar activity has declined as an inverse power law of age (between t -5 and t/sup -1.2/) as a consequence of angular momentum loss to the solar wind. Recent IUE satellite observations of premain sequence stars suggest that before the sun reached the main sequence (at an age of about 50 m.y.), it may have emitted as much as 10 4 times as much ultraviolet radiation (γ<2000 A) than it does today. These results could impact our understanding of the photochemistry and escape of constituents of primordial planetary atmospheres

  11. Solar ultraviolet radiation effects on biological systems

    International Nuclear Information System (INIS)

    Diffey, B.L.

    1991-01-01

    This extensive review discusses the topic under the following headings: ultraviolet climatology, molecular and cellular ultraviolet photobiology (absorption, photoproducts, repair), effects of solar UVR on aquatic life (phyto and zooplankton), plants and humans. The section on human effects includes tanning, photo-aging, non-melanoma and melanoma skin cancers and the effects of solar UVR on the eye. (UK)

  12. Solar ultraviolet radiation effects on biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Diffey, B.L. (Dryburn Hospital, Durham (UK). Regional Medical Physics Dept.)

    1991-03-01

    This extensive review discusses the topic under the following headings: ultraviolet climatology, molecular and cellular ultraviolet photobiology (absorption, photoproducts, repair), effects of solar UVR on aquatic life (phyto and zooplankton), plants and humans. The section on human effects includes tanning, photo-aging, non-melanoma and melanoma skin cancers and the effects of solar UVR on the eye. (UK).

  13. Dark Skies, Bright Kids! Year 3

    Science.gov (United States)

    Whelan, David G.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R. L.; Borish, J.; Corby, J. F.; Dorsey, G.; Gugliucci, N. E.; Prager, B. J.; Ries, P. A.; Romero, C. E.; Sokal, K. R.; Tang, X.; Walker, L. M.; Yang, A. J.; Zasowski, G.

    2012-01-01

    Dark Skies, Bright Kids! (DSBK) is a program that brings astronomy education to elementary schools throughout central Virginia. In a relaxed, out-of-classroom atmosphere, we are able to foster the innate curiosity that young students have about science and the world around them. We target schools that are under-served due to their rural locale or special needs students, demonstrating that science is a fun and creative process to a segment of the population that might not otherwise be exposed to astronomy. Families are included in the learning experience during semi-annual `star parties'. Since last January, we have expanded the breadth and depth of our educational capabilities. We have developed new programs for use in our digital planetarium. We held the first Central Virginia Star Party, providing an atmosphere where local children from multiple schools were able to share their love for astronomy. Local government and University officials were also invited so that they could experience our focused science outreach. Most recently, we have become part of Ivy Creek School's Club Day activities, bringing our program to a new segment of the elementary school system in Albemarle County: those that have `low-incidence' disabilities, requiring special attention. We continue to develop a curriculum for after-school programs that functions as either a series of one-time activities or several months of focused outreach at one school. Many of these activities are provided on our website, http://www.astro.virginia.edu/dsbk/, for the wider astronomical community, including the new planetarium work. We have extended our book project to include two bilingual astronomy books called `Snapshots of the Universe,' one in Spanish and English, the other in French and English. These books introduce young people to some of the many wonders of the Universe through art and captions developed by DSBK volunteers.

  14. Bright field electron microscopy of biological specimens

    International Nuclear Information System (INIS)

    Johansen, B.V.

    1976-01-01

    A preirradiation procedure is described which preserves negatively stained morphological features in bright field electron micrographs to a resolution of about 1.2 nm. Prior to microscopy the pre-irradiation dose (1.6 x 10 -3 C cm -2 ) is given at low electron optical magnification at five different areas on the grid (the centre plus four 'corners'). This pre-irradiation can be measured either with a Faraday cage or through controlled exposure-developing conditions. Uranyl formate stained T2 bacteriophages and stacked disk aggregates of Tobacco Mosaic Virus (TMV) protein served as test objects. A comparative study was performed on specimens using either the pre-irradiation procedure or direct irradiation by the 'minimum beam exposure' technique. Changes in the electron diffraction pattern of the stain-protein complex and the disappearance of certain morphological features in the specimens were both used in order to compare the pre-irradiation method with the direct exposure technique. After identical electron exposures the pre-irradiation approach gave a far better preservation of specimen morphology. Consequently this procedure gives the microscopist more time to select and focus appropriate areas for imaging before deteriorations take place. The investigation also suggested that microscopy should be carried out between 60,000 and 100,000 times magnification. Within this magnification range, it is possible to take advantage of the phase contrast transfer characteristics of the objective lens while the electron load on the object is kept at a moderate level. Using the pre-irradiation procedure special features of the T2 bacteriophage morphology could be established. (author)

  15. Dark Skies, Bright Kids! Year 4

    Science.gov (United States)

    Sokal, Kimberly R.; Johnson, K. E.; Barcos-Munoz, L. D.; Beaton, R.; Borish, J.; Crawford, S. B.; Corby, J.; Damke, G.; Dean, J.; Dorsey, G.; Jackson, L.; Liss, S.; Oza, A.; Peacock, S.; Prager, B.; Romero, C.; Sivakoff, G. R.; Walker, L.; Whelan, D. G.; Zucker, C.

    2013-01-01

    Aiming to engage young children's natural excitement and curiosity, the outreach group Dark Skies, Bright Kids (DSBK) brings a hands-on approach to astronomy to elementary schools in Virginia. We hope to enhance children's view and understanding of science while exploring the Universe using fun activities. DSBK focuses on rural and underserved schools in Albemarle County and offers a semester-long astronomy club for third through fifth grade students. We believe regular interactions foster personal relationships between students and volunteers that encourage a life-long interest in science. In our fourth year of hosting clubs, we returned to Ivy Creek Elementary School, where we saw wonderful responses from a special group of students with `low-incidence' disabilities. DSBK has grown to realize a broader reach beyond local astronomy clubs; we hope to ignite a spark of interest in astronomy and science more widely- in more children, their families, and their teachers. We also hosted the Second Annual Central Virginia Star Party with an open invitation to the community to encourage families to enjoy astronomy together. Throughout the year, DSBK now holds 'one-off' programs (akin to astronomy field days) for elementary schools and children's groups throughout Virginia. Furthermore, we are in the final stages of a project to create two bilingual astronomy books called "Snapshots of the Universe", in Spanish and French with English translations. This art book will be made available online and we are working to get a copy in every elementary school in the state. DSBK has begun to reach out to elementary school teachers in order to provide them with useful and engaging classroom material. We have adapted our volunteer-created activities into useful and ready-to-use lessons, available online. After improvements based on research through interactions and feedback from teachers, we have explicitly identified the learning goals in terms of Virginia's Standards of Learning

  16. Quantitative Brightness Analysis of Fluorescence Intensity Fluctuations in E. Coli.

    Directory of Open Access Journals (Sweden)

    Kwang-Ho Hur

    Full Text Available The brightness measured by fluorescence fluctuation spectroscopy specifies the average stoichiometry of a labeled protein in a sample. Here we extended brightness analysis, which has been mainly applied in eukaryotic cells, to prokaryotic cells with E. coli serving as a model system. The small size of the E. coli cell introduces unique challenges for applying brightness analysis that are addressed in this work. Photobleaching leads to a depletion of fluorophores and a reduction of the brightness of protein complexes. In addition, the E. coli cell and the point spread function of the instrument only partially overlap, which influences intensity fluctuations. To address these challenges we developed MSQ analysis, which is based on the mean Q-value of segmented photon count data, and combined it with the analysis of axial scans through the E. coli cell. The MSQ method recovers brightness, concentration, and diffusion time of soluble proteins in E. coli. We applied MSQ to measure the brightness of EGFP in E. coli and compared it to solution measurements. We further used MSQ analysis to determine the oligomeric state of nuclear transport factor 2 labeled with EGFP expressed in E. coli cells. The results obtained demonstrate the feasibility of quantifying the stoichiometry of proteins by brightness analysis in a prokaryotic cell.

  17. NIGHT SKY BRIGHTNESS ABOVE ZAGREB 2012.-2017.

    Directory of Open Access Journals (Sweden)

    Željko Andreić

    2018-01-01

    Full Text Available The night sky brightness at the RGN site (near the centre of Zagreb, Croatia was monitored form January 2012. to December 2017. The gathered data show that the average night sky brightness in this period did not change significantly, apart from differences caused by yearly variations in meteorological parameters. The nightly minima, maxima and mean values of the sky brightness do change considerably due to changes in meteorological conditions, often being between 2 and 3 magnitudes. The seasonal probability curves and histograms are constructed and are used to obtain additional information on the light pollution at the RGN site. They reveal that the night sky brightness clutters around two peaks, at about 15.0 mag/arcsec2 and at about 18.2 mag/arcsec2. The tendency to slightly lower brightness values in spring and summer can also be seen in the data. Two peaks correspond to cloudy and clear nights respectively, the difference in brightness between them being about 3 magnitudes. A crude clear/cloudy criterion can be defined too: the minimum between two peaks is around 16.7 mag/arcsec2. The brightness values smaller than thisare attributed to clear nights and vice-versa. Comparison with Vienna and Hong-Kong indicates that the light pollution of Zagreb is a few times larger.

  18. Ultraviolet safety assessments of insect light traps.

    Science.gov (United States)

    Sliney, David H; Gilbert, David W; Lyon, Terry

    2016-01-01

    Near-ultraviolet (UV-A: 315-400 nm), "black-light," electric lamps were invented in 1935 and ultraviolet insect light traps (ILTs) were introduced for use in agriculture around that time. Today ILTs are used indoors in several industries and in food-service as well as in outdoor settings. With recent interest in photobiological lamp safety, safety standards are being developed to test for potentially hazardous ultraviolet emissions. A variety of UV "Black-light" ILTs were measured at a range of distances to assess potential exposures. Realistic time-weighted human exposures are shown to be well below current guidelines for human exposure to ultraviolet radiation. These UV-A exposures would be far less than the typical UV-A exposure in the outdoor environment. Proposals are made for realistic ultraviolet safety standards for ILT products.

  19. Hand protection from ultraviolet exposure

    International Nuclear Information System (INIS)

    Khazova, M.; O'Hagan, J.B.

    2006-01-01

    Full text of publication follows: A number of industrial applications and public services involve exposure to ultraviolet radiation (U.V.R.) from a variety of lamps and lasers, for example, in forensic examination, biological trans-illuminators, dentistry, laser material processing, microelectronics, etc. The proposed European Union Directive on Optical Radiation would place specific requirements on employers to provide adequate safety measures to reduce exposure to U.V.R., including gloves for hand protection. The selection of gloves should be based on a risk assessment and on the performance characteristics of the gloves for the task. However, current International and national standards do not describe evaluation procedures of disposable gloves for hand protection against non-ionising radiation. A methodology for assessment of the UV protection level for disposable gloves and a simple measurement protocol are proposed, based on a common approach with UV protection by clothing and sunscreens. Glove Ultraviolet Protection Factor is defined as a time-scale increase in exposure permitted for the hand protected by a glove with respect to an unprotected hand. However, the wide variety of U.V.R. sources and the real-life conditions of glove use (stretching and wetting the surface by liquids) bring substantial challenges to the assessment method. Our study of ∼ 50 samples of widely used disposable gloves made of different materials (nitrile, vinyl, latex and chloroprene) showed that for all tested gloves a change in U.V.R. attenuation with stretching is characteristic for the type of glove material and can be included as a scaling factor in the definition of U.V.R. protection. Glove material has a bigger effect on U.V.R. protection level than variations in the glove thickness or its colour. The following approaches are suggested to overcome the problem of variable U.V.R. sources: - Worst case scenario minimal protection level, most restrictive case - Application

  20. Hand protection from ultraviolet exposure

    Energy Technology Data Exchange (ETDEWEB)

    Khazova, M.; O' Hagan, J.B. [Health Protection Agency, Radiation Protection Division, Chilton, Did cot (United Kingdom)

    2006-07-01

    Full text of publication follows: A number of industrial applications and public services involve exposure to ultraviolet radiation (U.V.R.) from a variety of lamps and lasers, for example, in forensic examination, biological trans-illuminators, dentistry, laser material processing, microelectronics, etc. The proposed European Union Directive on Optical Radiation would place specific requirements on employers to provide adequate safety measures to reduce exposure to U.V.R., including gloves for hand protection. The selection of gloves should be based on a risk assessment and on the performance characteristics of the gloves for the task. However, current International and national standards do not describe evaluation procedures of disposable gloves for hand protection against non-ionising radiation. A methodology for assessment of the UV protection level for disposable gloves and a simple measurement protocol are proposed, based on a common approach with UV protection by clothing and sunscreens. Glove Ultraviolet Protection Factor is defined as a time-scale increase in exposure permitted for the hand protected by a glove with respect to an unprotected hand. However, the wide variety of U.V.R. sources and the real-life conditions of glove use (stretching and wetting the surface by liquids) bring substantial challenges to the assessment method. Our study of {approx} 50 samples of widely used disposable gloves made of different materials (nitrile, vinyl, latex and chloroprene) showed that for all tested gloves a change in U.V.R. attenuation with stretching is characteristic for the type of glove material and can be included as a scaling factor in the definition of U.V.R. protection. Glove material has a bigger effect on U.V.R. protection level than variations in the glove thickness or its colour. The following approaches are suggested to overcome the problem of variable U.V.R. sources: - Worst case scenario minimal protection level, most restrictive case - Application

  1. The Ultraviolet Radiation Environment around M Dwarf Exoplanet Host Stars

    Science.gov (United States)

    France, Kevin; Froning, Cynthia S.; Linsky, Jeffrey L.; Roberge, Aki; Stocke, John T.; Tian, Feng; Bushinsky, Rachel; Desert, Jean-Michel; Mauas, Pablo; Mauas, Pablo; hide

    2013-01-01

    The spectral and temporal behavior of exoplanet host stars is a critical input to models of the chemistry and evolution of planetary atmospheres. Ultraviolet photons influence the atmospheric temperature profiles and production of potential biomarkers on Earth-like planets around these stars. At present, little observational or theoretical basis exists for understanding the ultraviolet spectra of M dwarfs, despite their critical importance to predicting and interpreting the spectra of potentially habitable planets as they are obtained in the coming decades. Using observations from the Hubble Space Telescope, we present a study of the UV radiation fields around nearby M dwarf planet hosts that covers both far-UV (FUV) and near-UV (NUV) wavelengths. The combined FUV+NUV spectra are publicly available in machine-readable format. We find that all six exoplanet host stars in our sample (GJ 581, GJ 876, GJ 436, GJ 832, GJ 667C, and GJ 1214) exhibit some level of chromospheric and transition region UV emission. No "UV-quiet" M dwarfs are observed. The bright stellar Lyman-alpha emission lines are reconstructed, and we find that the Lyman-alpha line fluxes comprise approximately 37%-75% of the total 1150-3100 A flux from most M dwarfs; approximately greater than 10(exp3) times the solar value. We develop an empirical scaling relation between Lyman-alpha and Mg II emission, to be used when interstellar H I attenuation precludes the direct observation of Lyman-alpha. The intrinsic unreddened flux ratio is F(Lyman-alpha)/F(Mg II) = 10(exp3). The F(FUV)/F(NUV) flux ratio, a driver for abiotic production of the suggested biomarkers O2 and O3, is shown to be approximately 0.5-3 for all M dwarfs in our sample, greather than 10(exp3) times the solar ratio. For the four stars with moderate signal-to-noise Cosmic Origins Spectrograph time-resolved spectra, we find UV emission line variability with amplitudes of 50%.500% on 10(exp2)-10(exp3) s timescales. This effect should be taken

  2. THE ULTRAVIOLET RADIATION ENVIRONMENT AROUND M DWARF EXOPLANET HOST STARS

    Energy Technology Data Exchange (ETDEWEB)

    France, Kevin; Froning, Cynthia S.; Stocke, John T.; Bushinsky, Rachel [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Linsky, Jeffrey L. [JILA, University of Colorado and NIST, 440 UCB, Boulder, CO 80309 (United States); Roberge, Aki [Exoplanets and Stellar Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Tian, Feng [Center for Earth System Sciences, Tsinghua University, Beijing 100084 (China); Desert, Jean-Michel [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Mauas, Pablo; Vieytes, Mariela [Instituto de Astronomsica del Espacio (CONICET-UBA), C.C. 67 Sucursal 28, 1428 Buenos Aires (Argentina); Walkowicz, Lucianne M., E-mail: kevin.france@colorado.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2013-02-15

    The spectral and temporal behavior of exoplanet host stars is a critical input to models of the chemistry and evolution of planetary atmospheres. Ultraviolet photons influence the atmospheric temperature profiles and production of potential biomarkers on Earth-like planets around these stars. At present, little observational or theoretical basis exists for understanding the ultraviolet spectra of M dwarfs, despite their critical importance to predicting and interpreting the spectra of potentially habitable planets as they are obtained in the coming decades. Using observations from the Hubble Space Telescope, we present a study of the UV radiation fields around nearby M dwarf planet hosts that covers both far-UV (FUV) and near-UV (NUV) wavelengths. The combined FUV+NUV spectra are publicly available in machine-readable format. We find that all six exoplanet host stars in our sample (GJ 581, GJ 876, GJ 436, GJ 832, GJ 667C, and GJ 1214) exhibit some level of chromospheric and transition region UV emission. No 'UV-quiet' M dwarfs are observed. The bright stellar Ly{alpha} emission lines are reconstructed, and we find that the Ly{alpha} line fluxes comprise {approx}37%-75% of the total 1150-3100 A flux from most M dwarfs; {approx}>10{sup 3} times the solar value. We develop an empirical scaling relation between Ly{alpha} and Mg II emission, to be used when interstellar H I attenuation precludes the direct observation of Ly{alpha}. The intrinsic unreddened flux ratio is F(Ly{alpha})/F(Mg II) = 10 {+-} 3. The F(FUV)/F(NUV) flux ratio, a driver for abiotic production of the suggested biomarkers O{sub 2} and O{sub 3}, is shown to be {approx}0.5-3 for all M dwarfs in our sample, >10{sup 3} times the solar ratio. For the four stars with moderate signal-to-noise Cosmic Origins Spectrograph time-resolved spectra, we find UV emission line variability with amplitudes of 50%-500% on 10{sup 2}-10{sup 3} s timescales. This effect should be taken into account in future UV

  3. Quadrature measurements of a bright squeezed state via sideband swapping

    DEFF Research Database (Denmark)

    Schneider, J.; Glockl, O.; Leuchs, G.

    2009-01-01

    The measurement of an arbitrary quadrature of a bright quantum state of light is a commonly requested action in many quantum information protocols, but it is experimentally challenging with previously proposed schemes. We suggest that the quadrature be measured at a specific sideband frequency...... of a bright quantum state by transferring the sideband modes under interrogation to a vacuum state and subsequently measuring the quadrature via homodyne detection. The scheme is implemented experimentally, and it is successfully tested with a bright squeezed state of light....

  4. THE ABSOLUTE MAGNITUDES OF TYPE Ia SUPERNOVAE IN THE ULTRAVIOLET

    International Nuclear Information System (INIS)

    Brown, Peter J.; Roming, Peter W. A.; Ciardullo, Robin; Gronwall, Caryl; Hoversten, Erik A.; Pritchard, Tyler; Milne, Peter; Bufano, Filomena; Mazzali, Paolo; Elias-Rosa, Nancy; Filippenko, Alexei V.; Li Weidong; Foley, Ryan J.; Hicken, Malcolm; Kirshner, Robert P.; Gehrels, Neil; Holland, Stephen T.; Immler, Stefan; Phillips, Mark M.; Still, Martin

    2010-01-01

    We examine the absolute magnitudes and light-curve shapes of 14 nearby (redshift z = 0.004-0.027) Type Ia supernovae (SNe Ia) observed in the ultraviolet (UV) with the Swift Ultraviolet/Optical Telescope. Colors and absolute magnitudes are calculated using both a standard Milky Way extinction law and one for the Large Magellanic Cloud that has been modified by circumstellar scattering. We find very different behavior in the near-UV filters (uvw1 rc covering ∼2600-3300 A after removing optical light, and u ∼ 3000-4000 A) compared to a mid-UV filter (uvm2 ∼2000-2400 A). The uvw1 rc - b colors show a scatter of ∼0.3 mag while uvm2-b scatters by nearly 0.9 mag. Similarly, while the scatter in colors between neighboring filters is small in the optical and somewhat larger in the near-UV, the large scatter in the uvm2 - uvw1 colors implies significantly larger spectral variability below 2600 A. We find that in the near-UV the absolute magnitudes at peak brightness of normal SNe Ia in our sample are correlated with the optical decay rate with a scatter of 0.4 mag, comparable to that found for the optical in our sample. However, in the mid-UV the scatter is larger, ∼1 mag, possibly indicating differences in metallicity. We find no strong correlation between either the UV light-curve shapes or the UV colors and the UV absolute magnitudes. With larger samples, the UV luminosity might be useful as an additional constraint to help determine distance, extinction, and metallicity in order to improve the utility of SNe Ia as standardized candles.

  5. Additive effects of ultraviolet radiation

    International Nuclear Information System (INIS)

    Cullen, A.P.

    1980-01-01

    A xenon-mercury high pressure lamp and a double monochromator were used to produce ultraviolet (uv) radiation at 295 nm. Pigmented rabbit eyes were irradiated and evaluated by slitlamp biomicroscopy. Corneal threshold (Hc) was 0.05 J.cm-2 and lens threshold (hL) was 0.75 J.cm-2. Other eyes were irradiated with 2 Hc and evaluated from 4 to 24 h at 4 h intervals. Corneal damage was only greater than that expected from a single Hc exposure if the separation between the two Hc exposures did not exceed 8 h. The most repeatable and reliable corneal response to these levels of uv was the development of corneal epithelial granules

  6. Ultraviolet Spectrophotometry of VV Cephei

    Directory of Open Access Journals (Sweden)

    Young Woon Kang

    1992-06-01

    Full Text Available The IUE archival spectra of VV Cephei were collected to investigate the eclipse nature in the ultraviolet. The temperature of the B star has been determined, as approximately 30000K, based on the flux distributions during egress. Light curves of VV Cephei were reduced from the spectrophotometry of the IUE archival spectra. Three light curves at the center wavelengths of 3250 Å, 2550 Å and 2850 Å have been analyzed by the modified Wilson and Devinney light curve program. The radii of the B star and M star were deduced to 0.05 and 0.22 of unit separation, respectively. The UV light curves show an evidence that the light was attenuated by the highly opaque atomsphere of the M star.

  7. Ultraviolet, Visible, and Fluorescence Spectroscopy

    Science.gov (United States)

    Penner, Michael H.

    Spectroscopy in the ultraviolet-visible (UV-Vis) range is one of the most commonly encountered laboratory techniques in food analysis. Diverse examples, such as the quantification of macrocomponents (total carbohydrate by the phenol-sulfuric acid method), quantification of microcomponents, (thiamin by the thiochrome fluorometric procedure), estimates of rancidity (lipid oxidation status by the thiobarbituric acid test), and surveillance testing (enzyme-linked immunoassays), are presented in this text. In each of these cases, the analytical signal for which the assay is based is either the emission or absorption of radiation in the UV-Vis range. This signal may be inherent in the analyte, such as the absorbance of radiation in the visible range by pigments, or a result of a chemical reaction involving the analyte, such as the colorimetric copper-based Lowry method for the analysis of soluble protein.

  8. Identifying Bright X-Ray Beasts

    Science.gov (United States)

    Kohler, Susanna

    2017-10-01

    Ultraluminous X-ray sources (ULXs) are astronomical sources of X-rays that, while dimmer than active galactic nuclei, are nonetheless brighter than any known stellar process. What are these beasts and why do they shine so brightly?Exceeding the LimitFirst discovered in the 1980s, ULXs are rare sources that have nonetheless been found in all types of galaxies. Though the bright X-ray radiation seems likely to be coming from compact objects accreting gas, theres a problem with this theory: ULXs outshine the Eddington luminosity for stellar-mass compact objects. This means that a stellar-mass object couldnt emit this much radiation isotropically without blowing itself apart.There are two alternative explanations commonly proposed for ULXs:Rather than being accreting stellar-mass compact objects, they are accreting intermediate-mass black holes. A hypothetical black hole of 100 solar masses or more would have a much higher Eddington luminosity than a stellar-mass black hole, making the luminosities that we observe from ULXs feasible.An example of one of the common routes the authors find for a binary system to become a ULX. In this case, the binary begins as two main sequence stars. As one star evolves off the main sequence, the binary undergoes a common envelope phase and a stage of mass transfer. The star ends its life as a supernova, and the resulting neutron star then accretes matter from the main sequence star as a ULX. [Wiktorowicz et al. 2017]They are ordinary X-ray binaries (a stellar-mass compact object accreting matter from a companion star), but they are undergoing a short phase of extreme accretion. During this time, their emission is beamed into jets, making them appear brighter than the Eddington luminosity.Clues from a New DiscoveryA few years ago, a new discovery shed some light on ULXs: M82 X-2, a pulsing ULX. Two more pulsing ULXs have been discovered since then, demonstrating that at least some ULXs contain pulsars i.e., neutron stars as the

  9. A new perspective on the infrared brightness temperature ...

    Indian Academy of Sciences (India)

    CEAWMT), ... temperatures clearly discriminates the cloud pixels of deep convective and ... utilized in the modelling of the histogram of infrared brightness temperature of deep convective and ..... Henderson-Sellers A 1978 Surface type and its effect.

  10. Operational Bright-Band Snow Level Detection Using Doppler Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method to detect the bright-band snow level from radar reflectivity and Doppler vertical velocity data collection with an atmospheric profiling Doppler radar. The...

  11. Visible Color and Photometry of Bright Materials on Vesta

    Science.gov (United States)

    Schroder, S. E.; Li, J. Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

    2012-01-01

    The Dawn Framing Camera (FC) collected images of the surface of Vesta at a pixel scale of 70 m in the High Altitude Mapping Orbit (HAMO) phase through its clear and seven color filters spanning from 430 nm to 980 nm. The surface of Vesta displays a large diversity in its brightness and colors, evidently related to the diverse geology [1] and mineralogy [2]. Here we report a detailed investigation of the visible colors and photometric properties of the apparently bright materials on Vesta in order to study their origin. The global distribution and the spectroscopy of bright materials are discussed in companion papers [3, 4], and the synthesis results about the origin of Vestan bright materials are reported in [5].

  12. Nimbus-5 ESMR Polar Gridded Brightness Temperatures, Version 2

    Data.gov (United States)

    National Aeronautics and Space Administration — The Nimbus-5 Electrically Scanning Microwave Radiometer (ESMR) data set consists of gridded brightness temperature arrays for the Arctic and Antarctic, spanning 11...

  13. Analytically derived conversion of spectral band radiance to brightness temperature

    Energy Technology Data Exchange (ETDEWEB)

    Berk, Alexander [Spectral Sciences, Inc., 44th Avenue, Burlington, MA 01803 (United States)], E-mail: lex@spectral.com

    2008-05-15

    Simple analytic expressions for brightness temperature have been derived in terms of band response function spectral moments. Accuracy measures are also derived. Application of these formulas to GOES-12 Sounder thermal infrared bands produces brightness temperature residuals between -5.0 and 2.5 mK for a 150-400 K temperature range. The magnitude of residuals for the five ASTER Radiometer thermal infrared bands over the same temperature range is less than 0.22 mK.

  14. The effect of bright lines in environmental risk communication

    International Nuclear Information System (INIS)

    Wilson, K.N.; Desvousges, W.H.; Smith, K.V.; Payne, J.

    1993-01-01

    Bright lines in environmental risk communication refer to the specific levels at which an environmental risk becomes a serious health threat and action should be taken to mitigate its effects. This study examined the effect of ''bright lines'' in risk communication by emphasizing the radon exposure threshold level of 4 picocuries per liter. Specifically, the authors developed a computer-assisted interview containing bright-line versions of risk information. The bright-line version contained a range of possible radon levels, the corresponding number of estimated lung cancer cases, the relative health risk from radon compared to other health risks, and the EPA guidelines for mitigating levels above 4 picocuries in the home. The non-bright line version was identical to the bright-line version, except it did not include the EPA's mitigation recommendations. Effect measures included respondents' change in perceived risk after reading their materials, intended testing behavior, and advice to their neighbor for a specified radon level either above or below the 4 picocury threshold level. This paper discusses broader policy implications for designing effective risk communication programs

  15. Stratospheric ozone, ultraviolet radiation and climate change

    International Nuclear Information System (INIS)

    Boucher, O.

    2008-01-01

    It is well known that an overexposure to ultraviolet radiation is associated with a number of health risks such as an increased risk of cataracts and skin cancers. At a time when climate change is often blamed for all our environmental problems, what is the latest news about the stratospheric ozone layer and other factors controlling ultraviolet radiation at the surface of the Earth? Will the expected changes in the chemical composition of the atmosphere and changes in our climate increase or decrease the risk for skin cancer? This article investigates the role of the various factors influencing ultraviolet radiation and presents the latest knowledge on the subject. (author)

  16. Ultraviolet safety assessments of insect light traps

    OpenAIRE

    Sliney, David H.; Gilbert, David W.; Lyon, Terry

    2016-01-01

    ABSTRACT Near-ultraviolet (UV-A: 315?400?nm), ?black-light,? electric lamps were invented in 1935 and ultraviolet insect light traps (ILTs) were introduced for use in agriculture around that time. Today ILTs are used indoors in several industries and in food-service as well as in outdoor settings. With recent interest in photobiological lamp safety, safety standards are being developed to test for potentially hazardous ultraviolet emissions. A variety of UV ?Black-light? ILTs were measured at...

  17. Some aspects of vacuum ultraviolet radiation physics

    CERN Document Server

    Damany, Nicole; Vodar, Boris

    2013-01-01

    Some Aspects of Vacuum Ultraviolet Radiation Physics presents some data on the state of research in vacuum ultraviolet radiation in association with areas of physics. Organized into four parts, this book begins by elucidating the optical properties of solids in the vacuum ultraviolet region (v.u.v.), particularly the specific methods of determination of optical constants in v.u.v., the properties of metals, and those of ionic insulators. Part II deals with molecular spectroscopy, with emphasis on the spectra of diatomic and simple polyatomic molecules, paraffins, and condensed phases. Part III

  18. Stimulation of hair cells with ultraviolet light

    Science.gov (United States)

    Azimzadeh, Julien B.; Fabella, Brian A.; Hudspeth, A. J.

    2018-05-01

    Hair bundles are specialized organelles that transduce mechanical inputs into electrical outputs. To activate hair cells, physiologists have resorted to mechanical methods of hair-bundle stimulation. Here we describe a new method of hair-bundle stimulation, irradiation with ultraviolet light. A hair bundle illuminated by ultraviolet light rapidly moves towards its tall edge, a motion typically associated with excitatory stimulation. The motion disappears upon tip-link rupture and is associated with the opening of mechanotransduction channels. Hair bundles can be induced to move sinusoidally with oscillatory modulation of the stimulation power. We discuss the implications of ultraviolet stimulation as a novel hair-bundle stimulus.

  19. Generation of Bright, Spatially Coherent Soft X-Ray High Harmonics in a Hollow Waveguide Using Two-Color Synthesized Laser Pulses.

    Science.gov (United States)

    Jin, Cheng; Stein, Gregory J; Hong, Kyung-Han; Lin, C D

    2015-07-24

    We investigate the efficient generation of low-divergence high-order harmonics driven by waveform-optimized laser pulses in a gas-filled hollow waveguide. The drive waveform is obtained by synthesizing two-color laser pulses, optimized such that highest harmonic yields are emitted from each atom. Optimization of the gas pressure and waveguide configuration has enabled us to produce bright and spatially coherent harmonics extending from the extreme ultraviolet to soft x rays. Our study on the interplay among waveguide mode, atomic dispersion, and plasma effect uncovers how dynamic phase matching is accomplished and how an optimized waveform is maintained when optimal waveguide parameters (radius and length) and gas pressure are identified. Our analysis should help laboratory development in the generation of high-flux bright coherent soft x rays as tabletop light sources for applications.

  20. Design of high-brightness TEM00-mode solar-pumped laser for renewable material processing

    Science.gov (United States)

    Liang, D.; Almeida, J.

    2014-08-01

    The conversion of sunlight into laser light by direct solar pumping is of ever-increasing importance because broadband, temporally constant, sunlight is converted into laser light, which can be a source of narrowband, collimated, rapidly pulsed, radiation with the possibility of obtaining extremely high brightness and intensity. Nonlinear processes, such as harmonic generation, might be used to obtain broad wavelength coverage, including the ultraviolet wavelengths, where the solar flux is very weak. The direct excitation of large lasers by sunlight offers the prospect of a drastic reduction in the cost of coherent optical radiation for high average power materials processing. This renewable laser has a large potential for many applications such as high-temperature materials processing, renewable magnesium-hydrogen energy cycle and so on. We propose here a scalable TEM00 mode solar laser pumping scheme, which is composed of four firststage 1.13 m diameter Fresnel lenses with its respective folding mirrors mounted on a two-axis automatic solar tracker. Concentrated solar power at the four focal spots of these Fresnel lenses are focused individually along a common 3.5 mm diameter, 70 mm length Nd:YAG rod via four pairs of second-stage fused-silica spherical lenses and third-stage 2D-CPCs (Compound Parabolic Concentrator), sitting just above the laser rod which is also double-pass pumped by four V-shaped pumping cavities. Distilled water cools both the rod and the concentrators. 15.4 W TEM00 solar laser power is numerically calculated, corresponding to 6.7 times enhancement in laser beam brightness.

  1. Ultraviolet vision in birds: the importance of transparent eye media.

    Science.gov (United States)

    Lind, Olle; Mitkus, Mindaugas; Olsson, Peter; Kelber, Almut

    2014-01-07

    Ultraviolet (UV)-sensitive visual pigments are widespread in the animal kingdom but many animals, for example primates, block UV light from reaching their retina by pigmented lenses. Birds have UV-sensitive (UVS) visual pigments with sensitivity maxima around 360-373 nm (UVS) or 402-426 nm (violet-sensitive, VS). We describe how these pigments are matched by the ocular media transmittance in 38 bird species. Birds with UVS pigments have ocular media that transmit more UV light (wavelength of 50% transmittance, λ(T0.5), 323 nm) than birds with VS pigments (λ(T0.5), 358 nm). Yet, visual models predict that colour discrimination in bright light is mostly dependent on the visual pigment (UVS or VS) and little on the ocular media. We hypothesize that the precise spectral tuning of the ocular media is mostly relevant for detecting weak UV signals, e.g. in dim hollow-nests of passerines and parrots. The correlation between eye size and UV transparency of the ocular media suggests little or no lens pigmentation. Therefore, only small birds gain the full advantage from shifting pigment sensitivity from VS to UVS. On the other hand, some birds with VS pigments have unexpectedly low UV transmission of the ocular media, probably because of UV blocking lens pigmentation.

  2. Unexpected Far-Ultraviolet Photometric Characteristics On Mimas

    Science.gov (United States)

    Royer, E. M.; Hendrix, A. R.

    2013-12-01

    While infrared and visible are the most common wavelength domains used to investigate planetary surfaces, ultraviolet (UV) data are significant and useful. Here, we present the first far-UV phase curves of Mimas, thus displaying another piece of the Saturnian System puzzle. Our preliminary results shows that, one more time, Mimas surface properties are far from what we was expected. Namely, we observe a leading hemisphere brighter than the trailing hemisphere at some far-UV wavelengths. We used the far-UV channel of the Cassini/UVIS instrument, ranging from 118 to 190 nm. Disk-integrated phase curves for the leading hemisphere and the trailing hemisphere, at 180nm, have been produced. Data points span from 0.5 to 163.5 degrees in phase angle. Mimas displays a leading hemisphere brighter than its trailing hemisphere, when theory and previous Voyager observations at longer wavelengths attest of a brighter trailing hemisphere due to the impact of the E-ring grains on this face of the satellite. Surprisingly, UVIS data show a very bright opposition effect on Mimas leading hemisphere, greater than what is observed on Tethys or Dione leading hemisphere at the same wavelength of 180 nm. Preliminary results of photometric properties modeling seem to indicate an important contribution of the coherent-backscattering process in the opposition surge. Exogenic processes such as bombardment by energetic electrons and/or E-ring grains are discussed to explain this unexpected surface property of Mimas.

  3. Sunscreens for delay of ultraviolet induction of skin tumors

    International Nuclear Information System (INIS)

    Wulf, H.C.; Poulsen, T.; Brodthagen, H.; Hou-Jensen, K.

    1982-01-01

    Sunscreens with different sun protection factors (SPFs) have been tested for their capability of delaying or preventing actinic damage and skin cancer development in groups of hairless, pigmented mice exposed to artificial ultraviolet (UV) light of increasing intensity. The dose delivered was less than or equal to 1 minimal erythema dose (MED) in the group of untreated mice, so that the mice to which sunscreens were applied never obtained a sunburn after UV exposure. The quality of UV light was similar to bright midday sun at a latitude of 56 degrees (city of Copenhagen). Tumorigenesis was demonstrated to be delayed corresponding to the SPF claimed by the manufacturer, but almost all of the UV-irradiated mice developed skin tumors. Histologic examination revealed actinic degeneration and tumors of squamous cell type with marked variation in differentiation. Metastases to lymph nodes and lungs were found in only 10%. Toxic reactions, such as eczematous-like skin reactions, dark coloring, and amyloidosis, were observed predominantly in the group treated with the sunscreen of highest SPF value. Long-term investigations seem to be necessary to unveil these problems--in particular, the specific SPF value, in sunscreens, that should be recommended to the public for prevention or delay of actinic damage and/or cancer development

  4. The Ultraviolet Surprise. Efficient Soft X-Ray High Harmonic Generation in Multiply-Ionized Plasmas

    International Nuclear Information System (INIS)

    Popmintchev, Dimitar; Hernandez-Garcia, Carlos; Dollar, Franklin; Mancuso, Christopher; Perez-Hernandez, Jose A.; Chen, Ming-Chang; Hankla, Amelia; Gao, Xiaohui; Shim, Bonggu; Gaeta, Alexander L.; Tarazkar, Maryam; Romanov, Dmitri A.; Levis, Robert J.; Gaffney, Jim A.; Foord, Mark; Libby, Stephen B.; Jaron-Becker, Agnieskzka; Becker, Andreas; Plaja, Luis; Muranane, Margaret M.; Kapteyn, Henry C.; Popmintchev, Tenio

    2015-01-01

    High-harmonic generation is a universal response of matter to strong femtosecond laser fields, coherently upconverting light to much shorter wavelengths. Optimizing the conversion of laser light into soft x-rays typically demands a trade-off between two competing factors. Reduced quantum diffusion of the radiating electron wave function results in emission from each species which is highest when a short-wavelength ultraviolet driving laser is used. But, phase matching - the constructive addition of x-ray waves from a large number of atoms - favors longer-wavelength mid-infrared lasers. We identified a regime of high-harmonic generation driven by 40-cycle ultraviolet lasers in waveguides that can generate bright beams in the soft x-ray region of the spectrum, up to photon energies of 280 electron volts. Surprisingly, the high ultraviolet refractive indices of both neutral atoms and ions enabled effective phase matching, even in a multiply ionized plasma. We observed harmonics with very narrow linewidths, while calculations show that the x-rays emerge as nearly time-bandwidt-limited pulse trains of ~100 attoseconds

  5. Photodetector of ultra-violet radiation

    International Nuclear Information System (INIS)

    Dorogan, V.; Vieru, T.; Coseac, V.; Chirita, F.

    1999-01-01

    The invention relates to photodetectors on the semiconductors base, in particular, to photodetectors of ultra-violet radiation and can be used in the optoelectronics systems for determining the intensity and dose of ultraviolet radiation emitted by the Sun and other sources. In the structure of the photodetector of ultraviolet radiation with a superficial potential barrier formed of semiconductors A 3 B 5 with the prohibited power width Eg 1 , solid solutions thereof with the prohibited power width Eg 2 and SnO 2 or ITO, in the semiconductors A 3 B 5 at a surface distance less than the absorption length of the visible radiation it is formed an isotype heterojunction between the semiconductors A 3 B 5 and solid solutions thereof with the prohibited power width Eg 2 > Eg 1 . The technical result consists in manufacturing of a photodetector sensitive solely to the ultraviolet radiation

  6. Outdoor ultraviolet exposure of children and adolescents

    International Nuclear Information System (INIS)

    Diffey, B.L.; Gibson, C.J.

    1996-01-01

    The weekday and weekend outdoor ultraviolet exposure of young people from primary and secondary schools in three geographically distinct regions of England was determined over a 3-month period in summer. Ultraviolet exposure was measured using personal film badges worn by each young person and time spent outdoors, in hourly intervals, assessed using exposure records. In each area a class of 9-10 year-old children from a primary school and a class of 14-15-year-old adolescents from a secondary school took part, giving a total of 180 subjects. We found that primary school children received higher outdoor ultraviolet exposure than young people in secondary schools, and geographical differences in exposure could not be accounted for solely by differences in ambient ultraviolet. There was little difference between the exposure of males and females. Children and adolescents did not behave as homogeneous groups with regard to exposure. (Author)

  7. Ultraviolet light - nature's own disinfection process

    Energy Technology Data Exchange (ETDEWEB)

    Munkeberg, T [Thorolf Gregersen a/s, Oslo (Norway)

    1978-05-18

    Ultraviolet radiation from the sun is the means by which natural pollution products, as well as much of the smaller amount of pollution products produced by man, are converted and returned to the cycle of nature. Artificial ultraviolet radiation offers an optimum method for the disinfection of drinking water and can be used in the long term without undesireable effects on man or the enviromment. There is no evidence that ultraviolet irradiation leads to radiation resistant mutations of bacteria. The geometrical arrangement of ultraviolet disinfection units is described and the capacities of typical units is mentioned as being 600-800 m/sup 3/ /hr, though there is no reason why this should not be increased.

  8. Ultraviolet light - nature's own disinfection process

    International Nuclear Information System (INIS)

    Munkeberg, T.

    1978-01-01

    Ultraviolet radiation from the sun is the means by which natural pollution products, as well as much of the smaller amount of pollution products produced by man, are converted and returned to the cycle of nature. Artificial ultraviolet radiation offers an optimum method for the disinfection of drinking water and can be used in the long term without undesireable effects on man or the enviromment. There is no evidence that ultraviolet irradiation leads to radiation resistant mutations of bacteria. The geometrical arrangement of ultraviolet disinfection units is described and the capacities of typical units is mentioned as being 600-800 m 3 /hr, though there is no reason why this should not be increased. (JIW)

  9. Inactivation of mitochondrial ATPase by ultraviolet light

    International Nuclear Information System (INIS)

    Chavez, E.; Cuellar, A.

    1984-01-01

    The present work describes experiments that show that far-ultraviolet irradiation induce the inhibition of ATPase activity in both membrane-bound and soluble F1. It was also found that ultraviolet light promotes the release of tightly bound adenine nucleotides from F1-ATPase. Experiments carried out with submitochondrial particles indicate that succinate partially protects against these effects of ultraviolet light. Titration of sulfhydryl groups in both irradiated submitochondrial particles and soluble F1-ATPase indicates that a conformational change induced by photochemical modifications of amino acid residues appears involved in the inactivation of the enzyme. Finally, experiments are described which show that the tyrosine residue located in the active site of F1-ATPase is modified by ultraviolet irradiation

  10. Stability and Transient Effects in Ultraviolet Filaments

    National Research Council Canada - National Science Library

    Niday, Thomas

    2004-01-01

    .... Much of the work in this field has been done with infrared pulses; however, it has been proposed that ultraviolet pulses have the advantage that longer pulse lengths can be used, thereby delivering more energy...

  11. PMMA Wettability Caused by Ultraviolet Radiation

    OpenAIRE

    Dehtjars, J; Lancere, L; Poļaka, N; Soudnikovich, A; Tjuļkins, F; Valters, V

    2010-01-01

    The article is targeted to explore ultraviolet radiation (UV) influence on PMMAf or eye prostheses. UV beingt he Sun lightc omponenta nd could effect PMMA surface that in turn contributesi nteractionw ith tear. PMMA wettabilityw as poweredb y UV.

  12. Ultraviolet treatment on high performance filaments

    International Nuclear Information System (INIS)

    Gu Huang

    2005-01-01

    Quartz, Kevlar, carbon, and glass filaments were irradiated by ultraviolet ray with various periods. Tensile strength of the treated fibres was tested and analyzed, and the outward appearance of the treated filaments was shown

  13. Vacuum-Ultraviolet Photovoltaic Detector.

    Science.gov (United States)

    Zheng, Wei; Lin, Richeng; Ran, Junxue; Zhang, Zhaojun; Ji, Xu; Huang, Feng

    2018-01-23

    Over the past two decades, solar- and astrophysicists and material scientists have been researching and developing new-generation semiconductor-based vacuum ultraviolet (VUV) detectors with low power consumption and small size for replacing traditional heavy and high-energy-consuming microchannel-detection systems, to study the formation and evolution of stars. However, the most desirable semiconductor-based VUV photovoltaic detector capable of achieving zero power consumption has not yet been achieved. With high-crystallinity multistep epitaxial grown AlN as a VUV-absorbing layer for photogenerated carriers and p-type graphene (with unexpected VUV transmittance >96%) as a transparent electrode to collect excited holes, we constructed a heterojunction device with photovoltaic detection for VUV light. The device exhibits an encouraging VUV photoresponse, high external quantum efficiency (EQE) and extremely fast tempera response (80 ns, 10 4 -10 6 times faster than that of the currently reported VUV photoconductive devices). This work has provided an idea for developing zero power consumption and integrated VUV photovoltaic detectors with ultrafast and high-sensitivity VUV detection capability, which not only allows future spacecraft to operate with longer service time and lower launching cost but also ensures an ultrafast evolution of interstellar objects.

  14. Human exposure to ultraviolet radiation

    International Nuclear Information System (INIS)

    Bernhardt, J.H.; Matthes, R.

    1987-01-01

    Ultraviolet radiation is that part of the electromagnetic spectrum located between the softest ionizing radiation and visible radiation. The lower limit of 100 nm is equivalent to photon energies of 12.4 eV, which corresponds approximately to the limit for the production of ionization in biologically important materials. A historical subdividing of the UV-region takes some of the biological effects into account. In this arrangement the range 400-315 nm, the so-called black light region, is called UV-A. In this wavelength region, fluorescence can be induced in many substances. UV-B covers the range 315-280 nm (the skin erythemal region). Most of the biologically active and potentially harmful UV from the sun reaching the surface of the earth is part of this spectral region. UV-C includes the radiation of wavelengths less than 280 nm (the germicidal region). It should be noted that this classification is somewhat arbitrary, and today it is more usual to evaluate the biological effectiveness of the whole UV-range from 200 to 400 nm

  15. Unintentional exposure to ultraviolet radiation

    International Nuclear Information System (INIS)

    Sliney, D.H.

    1987-01-01

    To evaluate the risks from unintentional exposure to ultraviolet radiation (UVR), and to consider hazard control regulation, one must face first the problem of their state of scientific knowledge and the public's perception of UVR. Few people in the general public would question the health benefits of sunlight. Many flock to the beaches each summer to develop a healthy tan. Since the 1920's scientists have recognized that most of the benefits--and risks--of sunlight exposure result from the UVR present in sunlight. Dermatologists warn sunbathers to avoid exposure or protect themselves against the intense midday UVR or risk skin cancer. A growing number of scientists warn of hazards to the eye if UVR--perhaps even shorter visible wavelengths--are not filtered by lenses. In addition to any intentional exposure for health or cosmetic purposes, many people are also exposed to UVR without being aware of it or without their intent to be exposed. Outdoor workers are exposed to sunlight, many industrial workers (e.g., welders) are exposed to UVR from arc sources, some UVR penetrates clothing, and people indoors are exposed to UVR from artificial lighting

  16. Dermal damage from ultraviolet radiation

    International Nuclear Information System (INIS)

    Kligman, L.H.

    1988-01-01

    Ultraviolet (UV) radiation is increasingly recognized as the cause of a vast number of changes in the skin of humans and animals. These include alterations at the molecular, cellular, tissue and systematic levels. In the recent past, much has been learned about the immediate effects in skin of acute UV exposure (i.e. sunburn) with its epidermal cell death, inflammation and vasolidation. With chronic exposure, many of the clinical and histologic effects can be seen only after decades. Visually, these are hyper- and hypopigmented macules, dry scaly, wrinkled skin with a variety of benign, pre-malignant and malignant neoplasms. All epidermal in origin, they lead, inexorably in humans, to the appearance the authors described as photo-aged. Underlying many of these visible manifestations are drastic changes in the dermis. These relate chiefly to destruction of mature collagen, with a compensatory overproduction of reticulin fibers, hyperplasia of elastic fibers eventuating in elastosis, increased levels of the glycosaminoglycans (GAGs) comprising the ground substance and changes in the microvasculature. First described in actinically damaged humans, systematic investigation required an animal model

  17. Masks for extreme ultraviolet lithography

    International Nuclear Information System (INIS)

    Cardinale, G; Goldsmith, J; Kearney, P A; Larson, C; Moore, C E; Prisbrey, S; Tong, W; Vernon, S P; Weber, F; Yan, P-Y.

    1998-01-01

    In extreme ultraviolet lithography (EUVL), the technology specific requirements on the mask are a direct consequence of the utilization of radiation in the spectral region between 10 and 15 nm. At these wavelengths, all condensed materials are highly absorbing and efficient radiation transport mandates the use of all-reflective optical systems. Reflectivity is achieved with resonant, wavelength-matched multilayer (ML) coatings on all of the optical surfaces - including the mask. The EUV mask has a unique architecture - it consists of a substrate with a highly reflective ML coating (the mask blank) that is subsequently over-coated with a patterned absorber layer (the mask). Particulate contamination on the EUVL mask surface, errors in absorber definition and defects in the ML coating all have the potential to print in the lithographic process. While highly developed technologies exist for repair of the absorber layer, no viable strategy for the repair of ML coating defects has been identified. In this paper the state-of-the-art in ML deposition technology, optical inspection of EUVL mask blank defects and candidate absorber patterning approaches are reviewed

  18. Ultraviolet complete dark energy model

    Science.gov (United States)

    Narain, Gaurav; Li, Tianjun

    2018-04-01

    We consider a local phenomenological model to explain a nonlocal gravity scenario which has been proposed to address dark energy issues. This nonlocal gravity action has been seen to fit the data as well as Λ -CDM and therefore demands a more fundamental local treatment. The induced gravity model coupled with higher-derivative gravity is exploited for this proposal, as this perturbatively renormalizable model has a well-defined ultraviolet (UV) description where ghosts are evaded. We consider a generalized version of this model where we consider two coupled scalar fields and their nonminimal coupling with gravity. In this simple model, one of the scalar field acquires a vacuum expectation value (VEV), thereby inducing a mass for one of the scalar fields and generating Newton's constant. The induced mass however is seen to be always above the running energy scale thereby leading to its decoupling. The residual theory after decoupling becomes a platform for driving the accelerated expansion under certain conditions. Integrating out the residual scalar generates a nonlocal gravity action. The leading term of which is the nonlocal gravity action used to fit the data of dark energy.

  19. Influence of near ultraviolet light on microorganisms

    International Nuclear Information System (INIS)

    Fraikin, G.Y.A.; Rubin, L.B.

    1980-01-01

    Our results and the recent literature data on the biological action of near ultraviolet light (300-380 nm) are examined in the review. Factual material is presented on the principles governing the manifestation of the following effects of near ultraviolet light in microorganisms: inactivation, delayed growth, photoreactivation, photoprotection, photoinduced sporulation (in fungi), and carotene synthesis. The mature and possible mechanisms of the effects examined are discussed

  20. Ultraviolet colors of subdwarf O stars

    International Nuclear Information System (INIS)

    Wesselius, P.R.

    1978-01-01

    The group of subdwarf O stars consisting of field stars and some central stars of old planetary nebulae does occupy an interesting place in the HR diagram. Greenstein and Sargent (1974) have tried to establish this place, and conclude that especially the hottest ones need ultraviolet data to improve the values of effective temperature and absolute luminosity. The author therefore observed some twenty sdO stars in the far ultraviolet using the spectrophotometer in the Netherlands' satellite ANS. (Auth.)

  1. Ultraviolet photoelectron spectroscopy of transient species

    International Nuclear Information System (INIS)

    Leeuw, D.M. de.

    1979-01-01

    Transient species are studied in the isolation of the gas phase using ultraviolet photoelectron spectroscopy (PES). A description of the equipment used and a discussion of some theoretical topics, which play a role in the interpretation of PE spectra, are given. Koopmans' theorem, Hartree-Fock-Slater (HFS) calculations and the sum rule are discussed. A versatile ultraviolet PE spectrometer, designed specifically for this purpose, has been built and the construction and performance of this instrument are described. (Auth.)

  2. Ultraviolet Behavior of N = 8 Supergravity

    International Nuclear Information System (INIS)

    Dixon, Lance J.

    2010-01-01

    In these lectures the author describes the remarkable ultraviolet behavior of N = 8 supergravity, which through four loops is no worse than that of N = 4 super-Yang-Mills theory (a finite theory). I also explain the computational tools that allow multi-loop amplitudes to be evaluated in this theory - the KLT relations and the unitarity method - and sketch how ultraviolet divergences are extracted from the amplitudes.

  3. Color and emotion: effects of hue, saturation, and brightness.

    Science.gov (United States)

    Wilms, Lisa; Oberfeld, Daniel

    2017-06-13

    Previous studies on emotional effects of color often failed to control all the three perceptual dimensions of color: hue, saturation, and brightness. Here, we presented a three-dimensional space of chromatic colors by independently varying hue (blue, green, red), saturation (low, medium, high), and brightness (dark, medium, bright) in a factorial design. The 27 chromatic colors, plus 3 brightness-matched achromatic colors, were presented via an LED display. Participants (N = 62) viewed each color for 30 s and then rated their current emotional state (valence and arousal). Skin conductance and heart rate were measured continuously. The emotion ratings showed that saturated and bright colors were associated with higher arousal. The hue also had a significant effect on arousal, which increased from blue and green to red. The ratings of valence were the highest for saturated and bright colors, and also depended on the hue. Several interaction effects of the three color dimensions were observed for both arousal and valence. For instance, the valence ratings were higher for blue than for the remaining hues, but only for highly saturated colors. Saturated and bright colors caused significantly stronger skin conductance responses. Achromatic colors resulted in a short-term deceleration in the heart rate, while chromatic colors caused an acceleration. The results confirm that color stimuli have effects on the emotional state of the observer. These effects are not only determined by the hue of a color, as is often assumed, but by all the three color dimensions as well as their interactions.

  4. Beam brightness calculation for analytical and empirical distribution functions

    International Nuclear Information System (INIS)

    Myers, T.J.; Boulais, K.A.; O, Y.S.; Rhee, M.J.

    1992-01-01

    The beam brightness, a figure of merit for a beam quality useful for high-current low-emittance beams, was introduced by van Steenbergen as B = I/V 4 , where I is the beam current and V 4 is the hypervolume in the four-dimensional trace space occupied by the beam particles. Customarily, the brightness is expressed in terms of the product of emittances ε x ε y as B = ηI/(π 2 ε x ε y ), where η is a form factor of order unity which depends on the precise definition of emittance and hypervolume. Recently, a refined definition of the beam brightness based on the arithmetic mean value defined in statistics is proposed. The beam brightness is defined as B triple-bond 4 > = I -1 ∫ ρ 4 2 dxdydx'dy', where I is the beam current given by I ∫ ρ 4 dxdydx'dy'. Note that in this definition, neither the hypervolume V 4 nor the emittance, are explicitly used; the brightness is determined solely by the distribution function. Brightnesses are unambiguously calculated and expressed analytically in terms of the respective beam current and effective emittance for a few commonly used distribution functions, including Maxwellian and water-bag distributions. Other distributions of arbitrary shape frequently encountered in actual experiments are treated numerically. The resulting brightnesses are expressed in the form B = ηI/(π 2 ε x ε y ), and η is found to be weakly dependent on the form of velocity distribution as well as spatial distribution

  5. Ultraviolet properties of the symbiotic stars

    International Nuclear Information System (INIS)

    Slovak, M.H.; Lambert, D.L.

    1982-01-01

    This article is an interim report on a survey of the symbiotic stars with the IUE satellite, both at low resolution and, for AG Pegasi and CH Cygni, at high resolution. The UV spectra, including both the emission lines and the continua, are presented and discussed. Since it is somewhat premature to draw general conclusions, the emphasis is biased towards a discussion of individual stars. AG Pegasi is used as an illustrative, albeit atypical, example. (Auth./C.F.)

  6. Brightness-normalized Partial Least Squares Regression for hyperspectral data

    International Nuclear Information System (INIS)

    Feilhauer, Hannes; Asner, Gregory P.; Martin, Roberta E.; Schmidtlein, Sebastian

    2010-01-01

    Developed in the field of chemometrics, Partial Least Squares Regression (PLSR) has become an established technique in vegetation remote sensing. PLSR was primarily designed for laboratory analysis of prepared material samples. Under field conditions in vegetation remote sensing, the performance of the technique may be negatively affected by differences in brightness due to amount and orientation of plant tissues in canopies or the observing conditions. To minimize these effects, we introduced brightness normalization to the PLSR approach and tested whether this modification improves the performance under changing canopy and observing conditions. This test was carried out using high-fidelity spectral data (400-2510 nm) to model observed leaf chemistry. The spectral data was combined with a canopy radiative transfer model to simulate effects of varying canopy structure and viewing geometry. Brightness normalization enhanced the performance of PLSR by dampening the effects of canopy shade, thus providing a significant improvement in predictions of leaf chemistry (up to 3.6% additional explained variance in validation) compared to conventional PLSR. Little improvement was made on effects due to variable leaf area index, while minor improvement (mostly not significant) was observed for effects of variable viewing geometry. In general, brightness normalization increased the stability of model fits and regression coefficients for all canopy scenarios. Brightness-normalized PLSR is thus a promising approach for application on airborne and space-based imaging spectrometer data.

  7. Sky brightness and twilight measurements at Jogyakarta city, Indonesia

    International Nuclear Information System (INIS)

    Herdiwijaya, Dhani

    2016-01-01

    The sky brightness measurements were performed using a portable photometer. A pocket-sized and low-cost photometer has 20 degree area measurement, and spectral ranges between 320-720 nm with output directly in magnitudes per arc second square (mass) unit. The sky brightness with 3 seconds temporal resolutions was recorded at Jogyakarta city (110° 25’ E; 70° 52’ S; elevation 100 m) within 136 days in years from 2014 to 2016. The darkest night could reach 22.61 mpass only in several seconds, with mean value 18.8±0.7 mpass and temperature variation 23.1±1.2 C. The difference of mean sky brightness between before and after midnight was about -0.76 mpass or 2.0 times brighter. Moreover, the sky brightness and temperature fluctuations were more stable in after midnight than in before midnight. It is suggested that city light pollution affects those variations, and subsequently duration of twilight. By comparing twilight brightness for several places, we also suggest a 17° solar dip or about 66 minutes before sunrise for new time of Fajr prayer. (paper)

  8. Ultraviolet resources over Northern Eurasia.

    Science.gov (United States)

    Chubarova, Natalia; Zhdanova, Yekaterina

    2013-10-05

    We propose a new climatology of UV resources over Northern Eurasia, which includes the assessments of both detrimental (erythema) and positive (vitamin D synthesis) effects of ultraviolet radiation on human health. The UV resources are defined by using several classes and subclasses - UV deficiency, UV optimum, and UV excess - for 6 different skin types. To better quantifying the vitamin D irradiance threshold we accounted for an open body fraction S as a function of effective air temperature. The spatial and temporal distribution of UV resources was estimated by radiative transfer (RT) modeling (8 stream DISORT RT code) with 1×1° grid and monthly resolution. For this purpose special datasets of main input geophysical parameters (total ozone content, aerosol characteristics, surface UV albedo, UV cloud modification factor) have been created over the territory of Northern Eurasia. The new approaches were used to retrieve aerosol parameters and cloud modification factor in the UV spectral region. As a result, the UV resources were obtained for clear-sky and mean cloudy conditions for different skin types. We show that the distribution of UV deficiency, UV optimum and UV excess is regulated by various geophysical parameters (mainly, total ozone, cloudiness and open body fraction) and can significantly deviate from latitudinal dependence. We also show that the UV optimum conditions can be simultaneously observed for people with different skin types (for example, for 4-5 skin types at the same time in spring over Western Europe). These UV optimum conditions for different skin types occupy a much larger territory over Europe than that over Asia. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Second COS FUV Lifetime Position: Verification of FUV Bright Object Aperture (BOA) Operations (FCAL4)

    Science.gov (United States)

    Debes, John H.

    2013-05-01

    As part of the calibration of the second lifetime position on the Cosmic Origins Spectrograph (COS) far-ultraviolet (FUV) detectors, observations of the external target, G191-B2B, were obtained with the G130M, G160M, and G140L gratings in combi- nation with the Bright Object Aperture. The observations were designed to verify the performance of these spectroscopic modes by reproducing similar observations taken during the SM4 Servicing Mission Observatory Verification (SMOV) of COS. These observations allowed for a detailed determination of the spatial location and profile of the spectra from the three gratings, as well as a determination of the spectral resolution of the G130M grating prior to and after the lifetime move. In general, the negligi- ble differences which exist between the two lifetime positions can be attributed to slight differences in the optical path. In particular, the spectral resolution appears to be slightly improved. The stability of the absolute and relative flux calibration was investigated for G130M as well using STIS echelle data of G191-B2B. We determine that the COS ab- solute flux calibration with the BOA is accurate to 10%, and flux calibrated data are reproducible at the 1-2% level since SMOV.

  10. DISCOVERY OF A BRIGHT, EXTREMELY LOW MASS WHITE DWARF IN A CLOSE DOUBLE DEGENERATE SYSTEM

    International Nuclear Information System (INIS)

    Vennes, S.; Kawka, A.; Nemeth, P.; Thorstensen, J. R.; Skinner, J. N.; Pigulski, A.; Steslicki, M.; Kolaczkowski, Z.; Srodka, P.

    2011-01-01

    We report the discovery of a bright (V ∼ 13.7), extremely low mass white dwarf in a close double degenerate system. We originally selected GALEX J171708.5+675712 for spectroscopic follow-up among a group of white dwarf candidates in an ultraviolet-optical reduced proper-motion diagram. The new white dwarf has a mass of 0.18 M sun and is the primary component of a close double degenerate system (P = 0.246137 days, K 1 = 288 km s -1 ) comprising a fainter white dwarf secondary with M 2 ∼ 0.9 M sun . Light curves phased with the orbital ephemeris show evidence of relativistic beaming and weaker ellipsoidal variations. The light curves also reveal secondary eclipses (depth ∼8 mmag) while the primary eclipses appear partially compensated by the secondary gravitational deflection and are below detection limits. Photospheric abundance measurements show a nearly solar composition of Si, Ca, and Fe (0.1-1 sun), while the normal kinematics suggest a relatively recent formation history. Close binary evolutionary scenarios suggest that extremely low mass white dwarfs form via a common-envelope phase and possible Roche lobe overflow.

  11. Multiband photometry and spectroscopy of an all-sky sample of bright white dwarfs

    Science.gov (United States)

    Raddi, R.; Gentile Fusillo, N. P.; Pala, A. F.; Hermes, J. J.; Gänsicke, B. T.; Chote, P.; Hollands, M. A.; Henden, A.; Catalán, S.; Geier, S.; Koester, D.; Munari, U.; Napiwotzki, R.; Tremblay, P.-E.

    2017-12-01

    The upcoming NASA Transiting Exoplanet Survey Satellite (TESS) will obtain space-based uninterrupted light curves for a large sample of bright white dwarfs distributed across the entire sky, providing a very rich resource for asteroseismological studies and the search for transits from planetary debris. We have compiled an all-sky catalogue of ultraviolet, optical and infrared photometry as well as proper motions, which we propose as an essential tool for the preliminary identification and characterization of potential targets. We present data for 1864 known white dwarfs and 305 high-probability white dwarf candidates brighter than 17 mag. We describe the spectroscopic follow-up of 135 stars, of which 82 are white dwarfs and 25 are hot subdwarfs. The new confirmed stars include six pulsating white dwarf candidates (ZZ Cetis), and nine white dwarf binaries with a cool main-sequence companion. We identify one star with a spectroscopic distance of only 25 pc from the Sun. Around the time TESS is launched, we foresee that all white dwarfs in this sample will have trigonometric parallaxes measured by the ESA Gaia mission next year.

  12. Bright and Not-So-Bright Prospects for Women in Physics in China-Beijing

    Science.gov (United States)

    Wu, Ling-An; Yang, Zhongqin; Ma, Wanyun

    2009-04-01

    Science in China-Beijing is enjoying a healthy increase in funding year by year, so the prospects for physicists are also bright. However, employment discrimination against women, formerly unthinkable, is becoming more and more explicit as the country evolves toward a market economy. Some recruitment notices bluntly state that only men will be considered, or impose restrictions upon potential female candidates. Female associate professors in many institutions are forced to retire at age 55, compared with 60 for men. This double-pinching discrimination against both younger and older women threatens to lead to a "pincer" effect, more serious than the "scissors" effect. Indeed, the ratio of senior-level women physicists in general has dropped significantly in recent years in China. Ironically, the number of female students applying for graduate studies is on the rise, as it is becoming increasingly difficult for them to compete with men in the job market with just an undergraduate degree. The Chinese Physical Society has made certain efforts to promote the image of women physicists, but it will take time and effort to reverse the trend.

  13. Retrieval of an ice water path over the ocean from ISMAR and MARSS millimeter and submillimeter brightness temperatures

    Science.gov (United States)

    Brath, Manfred; Fox, Stuart; Eriksson, Patrick; Chawn Harlow, R.; Burgdorf, Martin; Buehler, Stefan A.

    2018-02-01

    A neural-network-based retrieval method to determine the snow ice water path (SIWP), liquid water path (LWP), and integrated water vapor (IWV) from millimeter and submillimeter brightness temperatures, measured by using airborne radiometers (ISMAR and MARSS), is presented. The neural networks were trained by using atmospheric profiles from the ICON numerical weather prediction (NWP) model and by radiative transfer simulations using the Atmospheric Radiative Transfer Simulator (ARTS). The basic performance of the retrieval method was analyzed in terms of offset (bias) and the median fractional error (MFE), and the benefit of using submillimeter channels was studied in comparison to pure microwave retrievals. The retrieval is offset-free for SIWP > 0.01 kg m-2, LWP > 0.1 kg m-2, and IWV > 3 kg m-2. The MFE of SIWP decreases from 100 % at SIWP = 0.01 kg m-2 to 20 % at SIWP = 1 kg m-2 and the MFE of LWP from 100 % at LWP = 0.05 kg m-2 to 30 % at LWP = 1 kg m-2. The MFE of IWV for IWV > 3 kg m-2 is 5 to 8 %. The SIWP retrieval strongly benefits from submillimeter channels, which reduce the MFE by a factor of 2, compared to pure microwave retrievals. The IWV and the LWP retrievals also benefit from submillimeter channels, albeit to a lesser degree. The retrieval was applied to ISMAR and MARSS brightness temperatures from FAAM flight B897 on 18 March 2015 of a precipitating frontal system west of the coast of Iceland. Considering the given uncertainties, the retrieval is in reasonable agreement with the SIWP, LWP, and IWV values simulated by the ICON NWP model for that flight. A comparison of the retrieved IWV with IWV from 12 dropsonde measurements shows an offset of 0.5 kg m-2 and an RMS difference of 0.8 kg m-2, showing that the retrieval of IWV is highly effective even under cloudy conditions.

  14. Low dimensional neutron moderators for enhanced source brightness

    DEFF Research Database (Denmark)

    Mezei, Ferenc; Zanini, Luca; Takibayev, Alan

    2014-01-01

    In a recent numerical optimization study we have found that liquid para-hydrogen coupled cold neutron moderators deliver 3–5 times higher cold neutron brightness at a spallation neutron source if they take the form of a flat, quasi 2-dimensional disc, in contrast to the conventional more voluminous...... for cold neutrons. This model leads to the conclusions that the optimal shape for high brightness para-hydrogen neutron moderators is the quasi 1-dimensional tube and these low dimensional moderators can also deliver much enhanced cold neutron brightness in fission reactor neutron sources, compared...... to the much more voluminous liquid D2 or H2 moderators currently used. Neutronic simulation calculations confirm both of these theoretical conclusions....

  15. Bright Stuff on Ceres = Sulfates and Carbonates on CI Chondrites

    Science.gov (United States)

    Zolensky, Michael; Chan, Queenie H. S.; Gounelle, Matthieu; Fries, Marc

    2016-01-01

    Recent reports of the DAWN spacecraft's observations of the surface of Ceres indicate that there are bright areas, which can be explained by large amounts of the Mg sulfate hexahydrate (MgSO4•6(H2O)), although the identification appears tenuous. There are preliminary indications that water is being evolved from these bright areas, and some have inferred that these might be sites of contemporary hydro-volcanism. A heat source for such modern activity is not obvious, given the small size of Ceres, lack of any tidal forces from nearby giant planets, probable age and presumed bulk composition. We contend that observations of chondritic materials in the lab shed light on the nature of the bright spots on Ceres

  16. A high brightness probe of polymer nanoparticles for biological imaging

    Science.gov (United States)

    Zhou, Sirong; Zhu, Jiarong; Li, Yaping; Feng, Liheng

    2018-03-01

    Conjugated polymer nanoparticles (CPNs) with high brightness in long wavelength region were prepared by the nano-precipitation method. Based on fluorescence resonance energy transfer (FRET) mechanism, the high brightness property of the CPNs was realized by four different emission polymers. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) displayed that the CPNs possessed a spherical structure and an average diameter of 75 nm. Analysis assays showed that the CPNs had excellent biocompatibility, good photostability and low cytotoxicity. The CPNs were bio-modified with a cell penetrating peptide (Tat, a targeted element) through covalent link. Based on the entire wave fluorescence emission, the functionalized CPNs1-4 can meet multichannel and high throughput assays in cell and organ imaging. The contribution of the work lies in not only providing a new way to obtain a high brightness imaging probe in long wavelength region, but also using targeted cell and organ imaging.

  17. Low surface brightness galaxies in the cluster A1367

    International Nuclear Information System (INIS)

    Davies, J.I.; Phillipps, S.; Disney, M.J.

    1989-01-01

    We have obtained deep CCD frames of apparently blank regions of sky in the hope of detecting very low surface brightness (LSB) objects in the cluster A1367. We discuss our data reduction, and image detection and selection techniques. If the galaxies detected are actually cluster members then they are dwarfs and the conclusions of a previous paper on the Fornax cluster are essentially confirmed. One area of variance is that the lowest surface brightness galaxies do not appear to be preferentially concentrated towards the cluster centre. This can be explained by there being a much larger density of dwarf galaxies over this bright galaxy-rich region of the universe. We find over our small area approximately four times as many LSB galaxies as would be expected from our Fornax data. We speculate on the possible origin and likely intensity of intergalactic light within clusters. (author)

  18. Ultraviolet Spectroscopy of Asteroid(4) Vesta

    Science.gov (United States)

    Li, Jian-Yang; Bodewits, Dennis; Feaga, Lori M.; Landsman, Wayne; A'Hearn, Michael F.; Mutchler, Max J.; Russell, Christopher T.; McFadden, Lucy A.; Raymond, Carol A.

    2011-01-01

    We report a comprehensive review of the UV-visible spectrum and rotational lightcurve of Vesta combining new observations by Hubble Space Telescope and Swift with archival International Ultraviolet Explorer observations. The geometric albedos of Vesta from 220 nm to 953 nm arc derived by carefully comparing these observations from various instruments at different times and observing geometries. Vesta has a rotationally averaged geometric albedo of 0.09 at 250 nm, 0.14 at 300 nm, 0.26 at 373 nm, 0.38 at 673 nm, and 0.30 at 950 nm. The linear spectral slope in the ultraviolet displays a sharp minimum ncar sub-Earth longitude of 20deg, and maximum in the eastern hemisphere. This is completely consistent with the distribution of the spectral slope in the visible wavelength. The uncertainty of the measurement in the ultraviolet is approx.20%, and in the visible wavelengths better than 10%. The amplitude of Vesta's rotational lightcurves is approx.10% throughout the range of wavelengths we observed, but is smaller at 950 nm (approx.6%) ncar the 1-micron mafic band center. Contrary to earlier reports, we found no evidence for any difference between the phasing of the ultraviolet and visible/ncar-infrared lightcurves with respect to sub-Earth longitude. Vesta's average spectrum between 220 and 950 nm can well be described by measured reflectance spectra of fine particle howardite-like materials of basaltic achondrite meteorites. Combining this with the in-phase behavior of the ultraviolet, visible. and ncar-infrared lightcurves, and the spectral slopes with respect to the rotational phase, we conclude that there is no global ultraviolet/visible reversal on Vesta. Consequently, this implies lack of global space weathering on Vesta. Keyword,: Asteroid Vesta; Spectrophotometry; Spectroscopy; Ultraviolet observations; Hubble Space Telescope observations

  19. A near-infrared, optical, and ultraviolet polarimetric and timing investigation of complex equatorial dusty structures

    Science.gov (United States)

    Marin, F.; Rojas Lobos, P. A.; Hameury, J. M.; Goosmann, R. W.

    2018-05-01

    Context. From stars to active galactic nuclei, many astrophysical systems are surrounded by an equatorial distribution of dusty material that is, in a number of cases, spatially unresolved even with cutting edge facilities. Aims: In this paper, we investigate if and how one can determine the unresolved and heterogeneous morphology of dust distribution around a central bright source using time-resolved polarimetric observations. Methods: We used polarized radiative transfer simulations to study a sample of circumnuclear dusty morphologies. We explored a grid of geometrically variable models that are uniform, fragmented, and density stratified in the near-infrared, optical, and ultraviolet bands, and we present their distinctive time-dependent polarimetric signatures. Results: As expected, varying the structure of the obscuring equatorial disk has a deep impact on the inclination-dependent flux, polarization degree and angle, and time lags we observe. We find that stratified media are distinguishable by time-resolved polarimetric observations, and that the expected polarization is much higher in the infrared band than in the ultraviolet. However, because of the physical scales imposed by dust sublimation, the average time lags of months to years between the total and polarized fluxes are important; these time lags lengthens the observational campaigns necessary to break more sophisticated, and therefore also more degenerated, models. In the ultraviolet band, time lags are slightly shorter than in the infrared or optical bands, and, coupled to lower diluting starlight fluxes, time-resolved polarimetry in the UV appears more promising for future campaigns. Conclusions: Equatorial dusty disks differ in terms of inclination-dependent photometric, polarimetric, and timing observables, but only the coupling of these different markers can lead to inclination-independent constraints on the unresolved structures. Even though it is complex and time consuming, polarized

  20. Leonids 2017 from Norway – A bright surprise!

    Science.gov (United States)

    Gaarder, K.

    2018-01-01

    I am very pleased to have been able to observe near maximum activity of the Leonids, and clearly witnessed the unequal mass distribution during these hours. A lot of bright Leonids were seen, followed by a short period of high activity of fainter meteors, before a sharp drop in activity. The Leonids is undoubtedly a shower to watch closely, with its many variations in activity level and magnitude distribution. I already look forward to observing the next years’ display, hopefully under a dark and clear sky, filled with bright meteors!

  1. Sky Brightness During Eclipses: A Compendium from the Literature

    Science.gov (United States)

    1974-08-05

    Star Sightings 1880A 11 Jan 1880 Santa- Lucia Jupiter -3 Mars .3 No stars 1882A 17 May 1882 Sohag, Egypt Stars shone brightly 1883A 6 M.»y 1883...1870 E 1880 A 1886 BA 1887 F 1889 A2 1900 EB 1914 A 1927 B Location London Venice Bue Island Gottenbui g Vumpurthy Seville Santa- Lucia ...manner, and at the peak of day the stars ap- peared brightly. (Tatti Annali sacri della citta di Como.) 5 MAY 840 840 DB Ginzel p. 668 Italy In

  2. Brightness distribution data on 2918 radio sources at 365 MHz

    International Nuclear Information System (INIS)

    Cotton, W.D.; Owen, F.N.; Ghigo, F.D.

    1975-01-01

    This paper is the second in a series describing the results of a program attempting to fit models of the brightness distribution to radio sources observed at 365 MHz with the Bandwidth Synthesis Interferometer (BSI) operated by the University of Texas Radio Astronomy Observatory. Results for a further 2918 radio sources are given. An unresolved model and three symmetric extended models with angular sizes in the range 10--70 arcsec were attempted for each radio source. In addition, for 348 sources for which other observations of brightness distribution are published, the reference to the observations and a brief description are included

  3. Ultraviolet radiation therapy and UVR dose models

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, David Robert, E-mail: davidrobert.grimes@oncology.ox.ac.uk [School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland and Cancer Research UK/MRC Oxford Institute for Radiation Oncology, Gray Laboratory, University of Oxford, Old Road Campus Research Building, Oxford OX3 7DQ (United Kingdom)

    2015-01-15

    Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical dose estimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational dose estimation method in ultraviolet phototherapy is discussed.

  4. Ultraviolet radiation therapy and UVR dose models

    International Nuclear Information System (INIS)

    Grimes, David Robert

    2015-01-01

    Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical dose estimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational dose estimation method in ultraviolet phototherapy is discussed

  5. Solar ultraviolet irradiance variations: a review

    International Nuclear Information System (INIS)

    Lean, J.

    1987-01-01

    Despite the geophysical importance of solar ultraviolet radiation, specific aspects of its temporal variations have not yet been adequately determined experimentally, nor are the mechanisms for the variability completely understood. Satellite observations have verified the reality of solar ultraviolet irradiance variations over time scales of days and months, and model calculations have confirmed the association of these short-term variations with the evolution and rotation of regions of enhanced magnetic activity on the solar disc. However, neither rocket nor satellite measurements have yet been made with sufficient accuracy and regularity to establish unequivocally the nature of the variability over the longer time of the 11-year solar cycle. The comparative importance for the long-term variations of local regions of enhanced magnetic activity and global scale activity perturbations is still being investigated. Solar ultraviolet irradiance variations over both short and long time scales are reviewed, with emphasis on their connection to solar magnetic activity. Correlations with ground-based measures of solar variability are examined because of the importance of the ground-based observations as historical proxies of ultraviolet irradiance variations. Current problems in understanding solar ultraviolet irradiance variations are discussed, and the measurements planned for solar cycle 22, which may resolve these problems, are briefly described. copyright American Geophysical Union 1987

  6. Mutations induced by ultraviolet light

    International Nuclear Information System (INIS)

    Pfeifer, Gerd P.; You, Young-Hyun; Besaratinia, Ahmad

    2005-01-01

    The different ultraviolet (UV) wavelength components, UVA (320-400 nm), UVB (280-320 nm), and UVC (200-280 nm), have distinct mutagenic properties. A hallmark of UVC and UVB mutagenesis is the high frequency of transition mutations at dipyrimidine sequences containing cytosine. In human skin cancers, about 35% of all mutations in the p53 gene are transitions at dipyrimidines within the sequence 5'-TCG and 5'-CCG, and these are localized at several mutational hotspots. Since 5'-CG sequences are methylated along the p53 coding sequence in human cells, these mutations may be derived from sunlight-induced pyrimidine dimers forming at sequences that contain 5-methylcytosine. Cyclobutane pyrimidine dimers (CPDs) form preferentially at dipyrimidines containing 5-methylcytosine when cells are irradiated with UVB or sunlight. In order to define the contribution of 5-methylcytosine to sunlight-induced mutations, the lacI and cII transgenes in mouse fibroblasts were used as mutational targets. After 254 nm UVC irradiation, only 6-9% of the base substitutions were at dipyrimidines containing 5-methylcytosine. However, 24-32% of the solar light-induced mutations were at dipyrimidines that contain 5-methylcytosine and most of these mutations were transitions. Thus, CPDs forming preferentially at dipyrimidines with 5-methylcytosine are responsible for a considerable fraction of the mutations induced by sunlight in mammalian cells. Using mouse cell lines harboring photoproduct-specific photolyases and mutational reporter genes, we showed that CPDs (rather than 6-4 photoproducts or other lesions) are responsible for the great majority of UVB-induced mutations. An important component of UVB mutagenesis is the deamination of cytosine and 5-methylcytosine within CPDs. The mutational specificity of long-wave UVA (340-400 nm) is distinct from that of the shorter wavelength UV and is characterized mainly by G to T transversions presumably arising through mechanisms involving oxidized DNA

  7. Mutagenesis of Trichoderma Viride by Ultraviolet and Plasma

    International Nuclear Information System (INIS)

    Yao Risheng; Li Manman; Deng Shengsong; Hu Huajia; Wang Huai; Li Fenghe

    2012-01-01

    Considering the importance of a microbial strain capable of increased cellulase production, a mutant strain UP4 of Trichoderma viride was developed by ultraviolet (UV) and plasma mutation. The mutant produced a 21.0 IU/mL FPase which was 98.1% higher than that of the parent strain Trichoderma viride ZY-1. In addition, the effect of ultraviolet and plasma mutagenesis was not merely simple superimposition of single ultraviolet mutation and single plasma mutation. Meanwhile, there appeared a capsule around some of the spores after the ultraviolet and plasma treatment, namely, the spore surface of the strain became fuzzy after ultraviolet or ultraviolet and plasma mutagenesis.

  8. Mutagenesis of Trichoderma Viride by Ultraviolet and Plasma

    Science.gov (United States)

    Yao, Risheng; Li, Manman; Deng, Shengsong; Hu, Huajia; Wang, Huai; Li, Fenghe

    2012-04-01

    Considering the importance of a microbial strain capable of increased cellulase production, a mutant strain UP4 of Trichoderma viride was developed by ultraviolet (UV) and plasma mutation. The mutant produced a 21.0 IU/mL FPase which was 98.1% higher than that of the parent strain Trichoderma viride ZY-1. In addition, the effect of ultraviolet and plasma mutagenesis was not merely simple superimposition of single ultraviolet mutation and single plasma mutation. Meanwhile, there appeared a capsule around some of the spores after the ultraviolet and plasma treatment, namely, the spore surface of the strain became fuzzy after ultraviolet or ultraviolet and plasma mutagenesis.

  9. The ultraviolet variations of iota Cas

    Science.gov (United States)

    Molnar, M. R.; Mallama, A. D.; Soskey, D. G.; Holm, A. V.

    1976-01-01

    The Ap variable star iota Cas was observed with the photometers on OAO-2 covering the spectral range 1430-4250 A. The ultraviolet light curves show a double wave with primary minimum and maximum at phase ? 0.00 and 0.35, respectively. Secondary minimum light is at phase ? 0.65 with secondary maximum at phase ? 0.85. The light curves longward of 3150 A vary in opposition to those shortward of this 'null region'. Ground-based coude spectra show that the Fe II and Cr II line strengths have a double-wave variation such that maximum strength occurs at minimum ultraviolet light. We suggest that the strong ultraviolet opacities due to photoionization and line blanketing by these metals may cause the observed photometric variations. We have also constructed an oblique-rotator model which shows iron and chromium lying in a great circle band rather than in circular spots.

  10. JUDE: An Ultraviolet Imaging Telescope pipeline

    Science.gov (United States)

    Murthy, J.; Rahna, P. T.; Sutaria, F.; Safonova, M.; Gudennavar, S. B.; Bubbly, S. G.

    2017-07-01

    The Ultraviolet Imaging Telescope (UVIT) was launched as part of the multi-wavelength Indian AstroSat mission on 28 September, 2015 into a low Earth orbit. A 6-month performance verification (PV) phase ended in March 2016, and the instrument is now in the general observing phase. UVIT operates in three channels: visible, near-ultraviolet (NUV) and far-ultraviolet (FUV), each with a choice of broad and narrow band filters, and has NUV and FUV gratings for low-resolution spectroscopy. We have written a software package (JUDE) to convert the Level 1 data from UVIT into scientifically useful photon lists and images. The routines are written in the GNU Data Language (GDL) and are compatible with the IDL software package. We use these programs in our own scientific work, and will continue to update the programs as we gain better understanding of the UVIT instrument and its performance. We have released JUDE under an Apache License.

  11. The ultraviolet telescope on the Astron satellite

    International Nuclear Information System (INIS)

    Boyarchuk, A.A.

    1987-01-01

    On 23 March 1983 in the USSR, the Astron astrophysical satellite, with the largest ultraviolet telescope (the UVT) in the world (main mirror diameter 80 cm) and a set of X-ray instruments on board was placed in a high-apogee orbit. The design of the ultraviolet telescope and the results of some of the observations carried out with it are described here. The X-ray instruments are discussed in a separate article. The ultraviolet telescope on the Astron astrophysical satellite is a result of the joint efforts of scientists and engineers at the Crimean Astrophysical Observatory (Academy of Sciences of the USSR), the Byurakan Astrophysical Observatory (Academy of Sciences of the Armenian USSR), and several industrial enterprises in our country. The Laboratoire d'Astronomie Spatiale (CNRS, Marseille, France) played a large role in building the spectrometer for the UVT

  12. Fluorescence brightness and photostability of individual copper (I) oxide nanocubes.

    Science.gov (United States)

    Zohora, Nafisa; Kandjani, Ahmad Esmaielzadeh; Orth, Antony; Brown, Hannah M; Hutchinson, Mark R; Gibson, Brant C

    2017-12-04

    Conventional organic fluorophores lose their ability to fluoresce after repeated exposure to excitation light due to photobleaching. Therefore, research into emerging bright and photostable nanomaterials has become of great interest for a range of applications such as bio-imaging and tracking. Among these emerging fluorophores, metal oxide-based nanomaterials have attracted significant attention as a potential multifunctional material with photocatalytic and angeogenisis abilities in addition to fluorescnce applications. However, most of these applications are highly dependent on size, morphology, and chemo-physical properties of individual particles. In this manuscript, we present a method to study the intrinsic optical characteristics of individual copper (I) oxide (Cu 2 O) nanocubes. When excited at 520 nm using only 11 µW excitation power (1.7 W/cm2), individual nanocubes were observed to emit light with peak wavelengths ~760 nm which is conveniently within the near-infrared 1 (NIR1) biological window where tissue autofluorescence is minimal. Bright and photostable fluorescence was observed with intensities up to 487 K counts/s under constant illumination for at least 2 minutes with a brightness approximately four times higher than the autofluorescence from a fixed cumulus-oocyte complex. With near-IR emission, high fluorescence brightness, and outstanding photostability, Cu 2 O nanocubes are attractive candidates for long-term fluorescent bioimaging applications.

  13. Bright infrared LEDs based on colloidal quantum-dots

    KAUST Repository

    Sun, Liangfeng; Choi, Joshua J.; Stachnik, David; Bartnik, Adam C.; Hyun, Byung-Ryool; Malliaras, George G.; Hanrath, Tobias; Wise, Frank W.

    2013-01-01

    Record-brightness infrared LEDs based on colloidal quantum-dots have been achieved through control of the spacing between adjacent quantum-dots. By tuning the size of quantum-dots, the emission wavelengths can be tuned between 900nm and 1650nm. © 2013 Materials Research Society.

  14. The star-bright hour : [luuletused] / Betti Alver

    Index Scriptorium Estoniae

    Alver, Betti, 1906-1989

    2006-01-01

    Sisu: The star-bright hour ; Not a dream ; The Piper ; Corals in an ancent river. Luuletused pärinevad kogumikust "Tuulelaeval valgusest on aerud = Windship with Oars of Light. (Tallinn : Huma, 2001). Orig.: Tähetund ; Mitte viirastus, meelepett ; Vilepuhuja ; Korallid Emajões

  15. Optical variability of the medium-bright quasar sample

    International Nuclear Information System (INIS)

    Huang, K.; Mitchell, K.J.; Usher, P.D.

    1990-01-01

    A variability study of the 32-member Medium-Bright Quasar Sample is reported. It is found that the star US 1953 has undergone a noticeable variation in the course of 26 hr. Apparent variations in the extragalactic object US 3498 may be illusory, owing to its partially resolved appearance. No other evidence for variability was detected. 34 refs

  16. A surface brightness analysis of eight RR Lyrae stars

    International Nuclear Information System (INIS)

    Hawley, S.L.; Barnes, T.G. III; Moffett, T.J.

    1987-01-01

    The authors have used a surface brightness, (V-R) relation to analyze new contemporaneous photometry and radial velocity data for 6 RR-ab type stars and to re-analyze previously published data for RR Lyrae and X Arietis. Systematic effects were found in the surface brightness at phases near minimum radius. Excluding these phases, they determine the slope of the surface brightness relation and the mean radius for each star. They also find a zero point which includes both a distance term and the zero point of the surface brightness relation. The sample includes stars with Preston's metallicity indicator ΔS = 0 to 9, with periods ranging from 0.397 days to 0.651 days. Their results indicate a log(R/R solar ) vs. log P relation in the sense that stars with longer periods have larger radii, in agreement with theoretical predictions. Their radii are consistent with bolometric magnitudes in the range 0.2 - 0.8 magnitude but accurate magnitudes must await a reliable T e - color calibration

  17. Response of noctilucent cloud brightness to daily solar variations

    Science.gov (United States)

    Dalin, P.; Pertsev, N.; Perminov, V.; Dubietis, A.; Zadorozhny, A.; Zalcik, M.; McEachran, I.; McEwan, T.; Černis, K.; Grønne, J.; Taustrup, T.; Hansen, O.; Andersen, H.; Melnikov, D.; Manevich, A.; Romejko, V.; Lifatova, D.

    2018-04-01

    For the first time, long-term data sets of ground-based observations of noctilucent clouds (NLC) around the globe have been analyzed in order to investigate a response of NLC to solar UV irradiance variability on a day-to-day scale. NLC brightness has been considered versus variations of solar Lyman-alpha flux. We have found that day-to-day solar variability, whose effect is generally masked in the natural NLC variability, has a statistically significant effect when considering large statistics for more than ten years. Average increase in day-to-day solar Lyman-α flux results in average decrease in day-to-day NLC brightness that can be explained by robust physical mechanisms taking place in the summer mesosphere. Average time lags between variations of Lyman-α flux and NLC brightness are short (0-3 days), suggesting a dominant role of direct solar heating and of the dynamical mechanism compared to photodissociation of water vapor by solar Lyman-α flux. All found regularities are consistent between various ground-based NLC data sets collected at different locations around the globe and for various time intervals. Signatures of a 27-day periodicity seem to be present in the NLC brightness for individual summertime intervals; however, this oscillation cannot be unambiguously retrieved due to inevitable periods of tropospheric cloudiness.

  18. Matter-wave bright solitons in effective bichromatic lattice potentials

    Indian Academy of Sciences (India)

    Matter-wave bright solitons in bichromatic lattice potentials are considered and their dynamics for different lattice environments are studied. Bichromatic potentials are created from superpositions of (i) two linear optical lattices and (ii) a linear and a nonlinear optical lattice. Effective potentials are found for the solitons in both ...

  19. Matter wave interference pattern in the collision of bright solitons

    International Nuclear Information System (INIS)

    Kumar, V. Ramesh; Radha, R.; Panigrahi, Prasanta K.

    2009-01-01

    We investigate the dynamics of Bose-Einstein condensates in a quasi one-dimensional regime in a time-dependent trap and show analytically that it is possible to observe matter wave interference patterns in the intra-trap collision of two bright solitons by selectively tuning the trap frequency and scattering length.

  20. The morphology and surface brightness of extragalactic jets

    International Nuclear Information System (INIS)

    Bicknell, G.V.

    1983-01-01

    The problems associated with laminar flow models are reviewed, and an analogy between laboratory jets and astrophysical jets is given. The relationship between surface brightness and the jet full width half maximum is not in general as predicted by simple magnetohydrodynamic models. An alternative turbulent model is presented

  1. Minimum-phase distribution of cosmic source brightness

    International Nuclear Information System (INIS)

    Gal'chenko, A.A.; Malov, I.F.; Mogil'nitskaya, L.F.; Frolov, V.A.

    1984-01-01

    Minimum-phase distributions of brightness (profiles) for cosmic radio sources 3C 144 (the wave lambda=21 cm), 3C 338 (lambda=3.5 m), and 3C 353 (labda=31.3 cm and 3.5 m) are obtained. A real possibility for the profile recovery from module fragments of its Fourier-image is shown

  2. The "Brightness Rules" Alternative Conception for Light Bulb Circuits

    Science.gov (United States)

    Bryan, Joel A.; Stuessy, Carol

    2006-01-01

    An alternative conception for the observed differences in light bulb brightness was revealed during an unguided inquiry investigation in which prospective elementary teachers placed identical bulbs in series, parallel, and combination direct current circuits. Classroom observations, document analyses, and video and audio transcriptions led to the…

  3. The star-bright hour : [poems] / Betti Alver

    Index Scriptorium Estoniae

    Alver, Betti, 1906-1989

    2003-01-01

    Autori lühitutvustus lk. 231. Sisu: The star-bright hour ; The debt ; Not a dream ; Fog-bound ; Corals in an Ancient river ; Frou-frou 1-3. Orig.: Tähetund ; Vilepuhuja ; Võlg ; "Mitte viirastus, meelepett..." ; Udus ; Korallid Emajões ; Froufrou 1-3

  4. High-brightness fiber-coupled pump laser development

    Science.gov (United States)

    Price, Kirk; Karlsen, Scott; Leisher, Paul; Martinsen, Robert

    2010-02-01

    We report on the continued development of high brightness laser diode modules at nLIGHT Photonics. These modules, based on nLIGHT's PearlTM product platform, demonstrate excellence in output power, brightness, wavelength stabilization, and long wavelength performance. This system, based on 14 single emitters, is designed to couple diode laser light into a 105 μm fiber at an excitation NA of under 0.14. We demonstrate over 100W of optical power at 9xx nm with a diode brightness exceeding 20 MW/cm2-str with an operating efficiency of approximately 50%. Additional results show over 70W of optical coupled at 8xx nm. Record brilliance at wavelengths 14xx nm and longer will also be demonstrated, with over 15 W of optical power with a beam quality of 7.5 mm-mrad. These results of high brightness, high efficiency, and wavelength stabilization demonstrate the pump technology required for next generation solid state and fiber lasers.

  5. Near-infrared photometry of bright elliptical galaxies

    NARCIS (Netherlands)

    Peletier, R. F.; Valentijn, E. A.; Jameson, R. F.

    High-quality visual-infrared color profiles have been determined for elliptical galaxies for the first time. Surface photometry in J and K is presented for 12 bright elliptical galaxies, and the results have been combined with CCD data in visual passbands. It is shown that the galaxies become bluer

  6. 150 southern compact and bright-nucleus galaxies

    International Nuclear Information System (INIS)

    Fairall, A.P.

    1977-01-01

    Galaxies having regions of exceptionally high surface brightness have been selected from the ESO Quick Blue Survey and investigated by 'grating photography' -direct photography plus low-dispersion slitless spectroscopy. Two new Seyfert galaxies and a peculiar multiple system have been discovered. Differences in red continua are also noted. (author)

  7. Bright to dim oscillatory response of the Neurospora circadian oscillator.

    Science.gov (United States)

    Gooch, Van D; Johnson, Alicia E; Larrondo, Luis F; Loros, Jennifer J; Dunlap, Jay C

    2014-02-01

    The fungus Neurospora crassa constitutes an important model system extensively used in chronobiology. Several studies have addressed how environmental cues, such as light, can reset or synchronize a circadian system. By means of an optimized firefly luciferase reporter gene and a controllable lighting system, we show that Neurospora can display molecular circadian rhythms in dim light when cultures receive bright light prior to entering dim light conditions. We refer to this behavior as the "bright to dim oscillatory response" (BDOR). The bright light treatment can be applied up to 76 h prior to dim exposure, and it can be as short as 15 min in duration. We have characterized this response in respect to the duration of the light pulse, the time of the light pulse before dim, the intensity of dim light, and the oscillation dynamics in dim light. Although the molecular mechanism that drives the BDOR remains obscure, these findings suggest that a long-term memory of bright light exists as part of the circadian molecular components. It is important to consider the ecological significance of such dim light responses in respect to how organisms naturally maintain their timing mechanism in moonlight.

  8. The ultraviolet attenuation law in backlit spiral galaxies

    International Nuclear Information System (INIS)

    Keel, William C.; Manning, Anna M.; Holwerda, Benne W.; Lintott, Chris J.; Schawinski, Kevin

    2014-01-01

    The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly 'gray' law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that

  9. The Ultraviolet Attenuation Law in Backlit Spiral Galaxies

    Science.gov (United States)

    Keel, William C.; Manning, Anna M.; Holwerda, Benne W.; Lintott, Chris J.; Schawinski, Kevin

    2014-02-01

    The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly "gray" law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that widespread

  10. The ultraviolet attenuation law in backlit spiral galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Keel, William C. [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States); Manning, Anna M. [Stennis Space Center, MS 39522 (United States); Holwerda, Benne W. [ESA-ESTEC, Keplerlaan 1, 2201-AZ Noordwijk (Netherlands); Lintott, Chris J. [Astrophysics, Oxford University, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Schawinski, Kevin, E-mail: wkeel@ua.edu, E-mail: ammanning@bama.ua.edu, E-mail: bholwerd@rssd.esa.int, E-mail: Twitter@BenneHolwerda, E-mail: cjl@astro.ox.ac.uk, E-mail: Twitter@chrislintott, E-mail: kevin.schawinski@phys.ethz.ch, E-mail: Twitter@kevinschawinski [Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland)

    2014-02-01

    The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly 'gray' law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that

  11. Modelling and Display of the Ultraviolet Sky

    Science.gov (United States)

    Daniels, J.; Henry, R.; Murthy, J.; Allen, M.; McGlynn, T. A.; Scollick, K.

    1994-12-01

    A computer program is currently under development to model in 3D - one dimension of which is wavelength - all the known and major speculated sources of ultraviolet (900 A - 3100 A ) radiation over the celestial sphere. The software is being written in Fortran 77 and IDL and currently operates under IRIX (the operating system of the Silicon Graphics Iris Machine); all output models are in FITS format. Models along with display software will become available to the astronomical community. The Ultraviolet Sky Model currently includes the Zodiacal Light, Point Sources of Emission, and the Diffuse Galactic Light. The Ultraviolet Sky Model is currently displayed using SkyView: a package under development at NASA/ GSFC, which allows users to retrieve and display publically available all-sky astronomical survey data (covering many wavebands) over the Internet. We present a demonstration of the SkyView display of the Ultraviolet Model. The modelling is a five year development project: the work illustrated here represents product output at the end of year one. Future work includes enhancements to the current models and incorporation of the following models: Galactic Molecular Hydrogen Fluorescence; Galactic Highly Ionized Atomic Line Emission; Integrated Extragalactic Light; and speculated sources in the intergalactic medium such as Ionized Plasma and radiation from Non-Baryonic Particle Decay. We also present a poster which summarizes the components of the Ultraviolet Sky Model and outlines a further package that will be used to display the Ultraviolet Model. This work is supported by United States Air Force Contract F19628-93-K-0004. Dr J. Daniels is supported with a post-doctoral Fellowship from the Leverhulme Foundation, London, United Kingdom. We are also grateful for the encouragement of Dr Stephen Price (Phillips Laboratory, Hanscomb Air Force Base, MA)

  12. Far-Ultraviolet Characteristics of Lunar Swirls

    Science.gov (United States)

    Hendrix, A. R.; Greathouse, T. K.; Retherford, K. D.; Mandt, K. E.; Gladstone, G. R.; Kaufmann, D. E.; Hurley, D. M.; Feldman, P. D.; Pryor, W. R.; Bullock, M. A.; Stern, S. A.

    2015-10-01

    Lunar swirls are often described as bright sinuous regions of the Moon that appear to be relatively immature -i.e. less space-weathered than surrounding regions. Swirls are mysterious but seem to be linked to the interaction between the solar wind and the lunar magnetic anomalies (e.g., [1]). Commonly-studied swirls include Mare Ingenii (in a mare- highlands boundary region), Reiner Gamma (in a mare region), and Gerasimovich (in a highlands region). Swirls are known to be surface features: they have no expression at radar depths [2], exhibit no topography, and craters on swirls that penetrate the bright surface terrain reveal underlying dark material [3].

  13. Molecular geometry in the ultraviolet absorption spectra

    International Nuclear Information System (INIS)

    Albuquerque, S.F. de; Monteiro, L.S.; Adamis, L.M.B.; Baltar, M.C.P.; Silva, R.M. da

    1977-01-01

    The ultraviolet absorption spectra may be sensibly affected by steric effects. These effects can cause a lot of difficulties and unexpected changes in spectrum. The most general source of such difficulties is steric inhibition of resonance. In addition to this, ultraviolet epectra may be markedly changed by steric factors which change the positions of dipoles in the molecule with respect to each other and by the interaction of nonconjugated chromophores suitably located in space. We have studied in detail each of these effects presenting a lot of usual and importants examples in Organic Chemistry. Others relevants subjects were not considerated in this present work [pt

  14. Disinfection of drinking water by ultraviolet light

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    It is no longer mandatory that a given residue of chlorine is present in drinking water and this has led to interest in the use of ultraviolet radiation for disinfection of water in large public waterworks. After a brief discussion of the effect of ultraviolet radiation related to wavelength, the most usual type of irradiation equipment is briefly described. Practioal considerations regarding the installation, such as attenuation of the radiation due to water quality and deposits are presented. The requirements as to dose and residence time are also discussed and finally it is pointed out that hydraulic imperfections can reduce the effectiveness drastically. (JIW)Ψ

  15. Nanoscale freestanding gratings for ultraviolet blocking filters

    Energy Technology Data Exchange (ETDEWEB)

    van Beek, J.T.; Fleming, R.C.; Hindle, P.S.; Prentiss, J.D.; Schattenburg, M.L. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Ritzau, S. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1998-11-01

    Ultraviolet (UV) blocking filters are needed for atomic flux imaging in environments where high levels of ultraviolet radiation are present. Freestanding gratings are a promising candidate for UV filtering. They have a high aspect ratio ({approximately}13), narrow ({approximately}40 nm) slots, and effectively block UV radiation. The grating fabrication process makes use of several etching, electroplating, and lithographic steps and includes an optional step to plug pinholes induced by particles during processing. Gratings were successfully manufactured and tested. Measured UV transmissions of {approximately}10{sup {minus}5} and particle transmissions of {approximately}10{percent} are in agreement with theoretical predictions. {copyright} {ital 1998 American Vacuum Society.}

  16. Quartz glass behavior at ultraviolet spectrum region

    International Nuclear Information System (INIS)

    Braga, A.F.B.; Barbosa, L.C.; Evora, C.A.P.D.

    1990-01-01

    Melted quartz ingots were produced from raw materials of different sources. Behavior studies of these three different quartz glass were made at the eletromagnetic spectrum ultraviolet region. The atomic absorption spectroscopy was used as an analysis technique of the alkaline, transition and aluminum metal traces. It was found that the alkaline, transition and aluminum metals impurities present a great influence on the melted quartz spectral behavior at the ultraviolet region. It was stated that measurments at this spectrum region constitute an important characterization technique to natural quartz as well as melted quartz. (author) [pt

  17. Progress in extremely high brightness LED-based light sources

    Science.gov (United States)

    Hoelen, Christoph; Antonis, Piet; de Boer, Dick; Koole, Rolf; Kadijk, Simon; Li, Yun; Vanbroekhoven, Vincent; Van De Voorde, Patrick

    2017-09-01

    Although the maximum brightness of LEDs has been increasing continuously during the past decade, their luminance is still far from what is required for multiple applications that still rely on the high brightness of discharge lamps. In particular for high brightness applications with limited étendue, e.g. front projection, only very modest luminance values in the beam can be achieved with LEDs compared to systems based on discharge lamps or lasers. With dedicated architectures, phosphor-converted green LEDs for projection may achieve luminance values up to 200-300 Mnit. In this paper we report on the progress made in the development of light engines based on an elongated luminescent concentrator pumped by blue LEDs. This concept has recently been introduced to the market as ColorSpark High Lumen Density LED technology. These sources outperform the maximum brightness of LEDs by multiple factors. In LED front projection, green LEDs are the main limiting factor. With our green modules, we now have achieved peak luminance values of 2 Gnit, enabling LED-based projection systems with over 4000 ANSI lm. Extension of this concept to yellow and red light sources is presented. The light source efficiency has been increased considerably, reaching 45-60 lm/W for green under practical application conditions. The module architecture, beam shaping, and performance characteristics are reviewed, as well as system aspects. The performance increase, spectral range extensions, beam-shaping flexibility, and cost reductions realized with the new module architecture enable a breakthrough in LED-based projection systems and in a wide variety of other high brightness applications.

  18. SKYMONITOR: A Global Network for Sky Brightness Measurements

    Science.gov (United States)

    Davis, Donald R.; Mckenna, D.; Pulvermacher, R.; Everett, M.

    2010-01-01

    We are implementing a global network to measure sky brightness at dark-sky critical sites with the goal of creating a multi-decade database. The heart of this project is the Night Sky Brightness Monitor (NSBM), an autonomous 2 channel photometer which measures night sky brightness in the visual wavelengths (Mckenna et al, AAS 2009). Sky brightness is measured every minute at two elevation angles typically zenith and 20 degrees to monitor brightness and transparency. The NSBM consists of two parts, a remote unit and a base station with an internet connection. Currently these devices use 2.4 Ghz transceivers with a range of 100 meters. The remote unit is battery powered with daytime recharging using a solar panel. Data received by the base unit is transmitted via email protocol to IDA offices in Tucson where it will be collected, archived and made available to the user community via a web interface. Two other versions of the NSBM are under development: one for radio sensitive areas using an optical fiber link and the second that reads data directly to a laptop for sites without internet access. NSBM units are currently undergoing field testing at two observatories. With support from the National Science Foundation, we will construct and install a total of 10 units at astronomical observatories. With additional funding, we will locate additional units at other sites such as National Parks, dark-sky preserves and other sites where dark sky preservation is crucial. We will present the current comparison with the National Park Service sky monitoring camera. We anticipate that the SKYMONITOR network will be functioning by the end of 2010.

  19. Diode lasers optimized in brightness for fiber laser pumping

    Science.gov (United States)

    Kelemen, M.; Gilly, J.; Friedmann, P.; Hilzensauer, S.; Ogrodowski, L.; Kissel, H.; Biesenbach, J.

    2018-02-01

    In diode laser applications for fiber laser pumping and fiber-coupled direct diode laser systems high brightness becomes essential in the last years. Fiber coupled modules benefit from continuous improvements of high-power diode lasers on chip level regarding output power, efficiency and beam characteristics resulting in record highbrightness values and increased pump power. To gain high brightness not only output power must be increased, but also near field widths and far field angles have to be below a certain value for higher power levels because brightness is proportional to output power divided by beam quality. While fast axis far fields typically show a current independent behaviour, for broadarea lasers far-fields in the slow axis suffer from a strong current and temperature dependence, limiting the brightness and therefore their use in fibre coupled modules. These limitations can be overcome by carefully optimizing chip temperature, thermal lensing and lateral mode structure by epitaxial and lateral resonator designs and processing. We present our latest results for InGaAs/AlGaAs broad-area single emitters with resonator lengths of 4mm emitting at 976nm and illustrate the improvements in beam quality over the last years. By optimizing the diode laser design a record value of the brightness for broad-area lasers with 4mm resonator length of 126 MW/cm2sr has been demonstrated with a maximum wall-plug efficiency of more than 70%. From these design also pump modules based on 9 mini-bars consisting of 5 emitters each have been realized with 360W pump power.

  20. Plasmonic enhancement of ultraviolet fluorescence

    Science.gov (United States)

    Jiao, Xiaojin

    Plasmonics relates to the interaction between electromagnetic radiation and conduction electrons at metallic interfaces or in metallic nanostructures. Surface plasmons are collective electron oscillations at a metal surface, which can be manipulated by shape, texture and material composition. Plasmonic applications cover a broad spectrum from visible to near infrared, including biosensing, nanolithography, spectroscopy, optoelectronics, photovoltaics and so on. However, there remains a gap in this activity in the ultraviolet (UV, research. Motivating factors in the study of UV Plasmonics are the direct access to biomolecular resonances and native fluorescence, resonant Raman scattering interactions, and the potential for exerting control over photochemical reactions. This dissertation aims to fill in the gap of Plasmonics in the UV with efforts of design, fabrication and characterization of aluminium (Al) and magnesium (Mg) nanostructures for the application of label-free bimolecular detection via native UV fluorescence. The first contribution of this dissertation addresses the design of Al nanostructures in the context of UV fluorescence enhancement. A design method that combines analytical analysis with numerical simulation has been developed. Performance of three canonical plasmonic structures---the dipole antenna, bullseye nanoaperture and nanoaperture array---has been compared. The optimal geometrical parameters have been determined. A novel design of a compound bullseye structure has been proposed and numerically analyzed for the purpose of compensating for the large Stokes shift typical of UV fluorescence. Second, UV lifetime modification of diffusing molecules by Al nanoapertures has been experimentally demonstrated for the first time. Lifetime reductions of ~3.5x have been observed for the high quantum yield (QY) laser dye p-terphenyl in a 60 nm diameter aperture with 50 nm undercut. Furthermore, quantum-yield-dependence of lifetime reduction has been

  1. ESA innovation rescues Ultraviolet Observatory

    Science.gov (United States)

    1995-10-01

    Astrophysicist Freeman J. Dyson from the Institute for Advanced Studies in Princeton characterizes IUE as "A little half-meter mirror sitting in the sky, unnoticed by the public, pouring out results". By use of the IUE satellite, astronomers obtain access to the ultraviolet radiation of celestial bodies in unique ways not available by any other means, neither from the ground nor by any other spacecraft currently in orbit. IUE serves a wide community of astronomers all over Europe, the United States and many other parts of the world. It allows the acquisition of critical data for fundamental studies of comets and their evaporation when they approach the Sun, of the mechanisms driving the stellar winds which make many stars lose a significant fraction of their mass (before they die slowly as White Dwarfs or in sudden Supernova explosions), as well as in the search to understand the ways in which black holes possibly power the violent nuclei of Active galaxies. One year ago the project was threatened with termination and serious concern was expressed by astronomers about the potential loss of IUE's capabilities, as a result of NASA not continuing to operate the spacecraft. Under the leadership of ESA, the three Agencies involved in the operations of IUE (ESA, NASA and the United Kingdom's Particle Physics and Astronomy Research Council, PPARC), reviewed the operations agreements of the Project. A minor investment allowing the implementation of modern management and engineering techniques as well as a complete revision of the communication infrastructure of the project and continuous improvements in efficiency in the ESA management, also taking advantage of today's technologies, both in computing and communications, have made it possible to continue IUE operations within the financial means available, with ESA taking up most of NASA's share in the operations. According to Dr. Willem Wamsteker, ESA's Dutch IUE Project Scientist, "it was a extremely interesting

  2. Far-ultraviolet spectral changes of titanium dioxide with gold nanoparticles by ultraviolet and visible light

    Science.gov (United States)

    Tanabe, Ichiro; Kurawaki, Yuji

    2018-05-01

    Attenuated total reflectance spectra including the far-ultraviolet (FUV, ≤ 200 nm) region of titanium dioxide (TiO2) with and without gold (Au) nanoparticles were measured. A newly developed external light-irradiation system enabled to observe spectral changes of TiO2 with Au nanoparticles upon light irradiations. Absorption in the FUV region decreased and increased by the irradiation with ultraviolet and visible light, respectively. These spectral changes may reflect photo-induced electron transfer from TiO2 to Au nanoparticles under ultraviolet light and from Au nanoparticles to TiO2 under visible light, respectively.

  3. LARGER PLANET RADII INFERRED FROM STELLAR ''FLICKER'' BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS

    International Nuclear Information System (INIS)

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua

    2014-01-01

    Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ( f licker ) of stars can be used to measure log g to a high accuracy of ∼0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T eff = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested

  4. Hubble Space Telescope Ultraviolet Spectroscopy of Fourteen Low-Redshift Quasars

    DEFF Research Database (Denmark)

    Ganguly, Rajib; Brotherton, Michael S.; Arav, Nahum

    2007-01-01

    We present low-resolution ultraviolet spectra of 14 low redshift (z zz 1.4 Large Bright Quasar samples. By design, our objects sample luminosities in between these two surveys, and our four absorbed objects are consistent with the v ~ L^0.62 relation derived by Laor & Brandt (2002). Another quasar......, HE0441-2826, contains extremely weak emission lines and our spectrum is consistent with a simple power-law continuum. The quasar is radio-loud, but has a steep spectral index and a lobe-dominated morphology, which argues against it being a blazar. The unusual spectrum of this quasar resembles...... the spectra of the quasars PG1407+265, SDSSJ1136+0242, and PKS1004+13 for which several possible explanations have been entertained....

  5. New high-resolution rocket-ultraviolet filtergrams of the solar disc

    Science.gov (United States)

    Foing, B.; Bonnet, R.-M.; Bruner, M.

    1986-01-01

    A rocket-borne solar ultraviolet telescope named Transition Region Camera was launched successfully for the third on July 13, 1982. High quality calibrated photographic images of the sun were obtained at Lyman alpha and in the continuum at 160 nm and 220 nm. The angular resolution achieved is better than one arcsec. A flare, active regions, sunspots, the 8 Mm mesostructure, the chromospheric network, bright UV grains and coronal loops were observed during the flight. The results are presented and the evolution with height in the solar atmosphere of the various structures observed is followed from one wavelength to the other, showing distinct differences. The value of the field's intensity of magnetic flux tubes is deduced from the observations.

  6. The relationship between brightness temperature and soil moisture. Selection of frequency range for microwave remote sensing

    International Nuclear Information System (INIS)

    Rao, K.S.; Chandra, G.; Rao, P.V.N.

    1987-01-01

    The analysis of brightness temperature data acquired from field and aircraft experiments demonstrates a linear relationship between soil moisture and brightness temperature. However, the analysis of brightness temperature data acquired by the Skylab radiometer demonstrates a non-linear relationship between soil moisture and brightness temperature. In view of the above and also because of recent theoretical developments for the calculation of the dielectric constant and brightness temperature under varying soil moisture profile conditions, an attempt is made to study the theoretical relationship between brightness temperature and soil moisture as a function of frequency. Through the above analysis, the appropriate microwave frequency range for soil moisture studies is recommended

  7. Ultraviolet reflection enhances the risk of predation in a vertebrate

    Directory of Open Access Journals (Sweden)

    Ricarda MODARRESSIE, Ingolf P. RICK, Theo C. M. BAKKER

    2013-04-01

    Full Text Available Many animals are sensitive to ultraviolet light and also possess UV-reflective regions on their body surface. Individuals reflecting UV have been shown to be preferred during social interactions such as mate choice or shoaling decisions. However, whether those body UV-reflections enhance also the conspicuousness to UV-sensitive predators and therefore entail costs for its bearer is less well documented. Two size-matched three-spined sticklebacks Gasterosteus aculeatus, one enclosed in a UV-transmitting (UV+ and another in a UV-blocking (UV- chamber, were simultaneously presented to individual brown trout Salmo trutta. “yearlings”. Brown trout of this age are sensitive to the UV part of the electromagnetic spectrum and are natural predators of three-spined sticklebacks. The stickleback that was attacked first as well as the subsequent number of attacks was recorded. Sticklebacks enclosed in the UV-transmitting chamber were attacked first significantly more often compared to sticklebacks enclosed in the UV-blocking chamber. Control experiments using neutral density filters revealed that this was more likely due to UV having an influence on hue perception rather than brightness discrimination. The difference in attack probability corresponded to the difference in chromatic contrasts between sticklebacks and the experimental background calculated for both the UV+ and UV- conditions in a physiological model of trout colour vision. UV reflections seem to be costly by enhancing the risk of predation due to an increased conspicuousness of prey. This is the first study in a vertebrate, to our knowledge, demonstrating direct predation risk due to UV wavelengths [Current Zoology 59 (2: 151-159, 2013].

  8. Solar ultraviolet radiation in a changing climate

    Science.gov (United States)

    The projected large increases in damaging ultraviolet radiation as a result of global emissions of ozone-depleting substances have been forestalled by the success of the Montreal Protocol. New challenges are now arising in relation to climate change. We highlight the complex inte...

  9. Habitat impact on ultraviolet reflectance in moths

    Czech Academy of Sciences Publication Activity Database

    Zapletalová, Lenka; Zapletal, Michal; Konvička, Martin

    2016-01-01

    Roč. 45, č. 5 (2016), s. 1300-1305 ISSN 0046-225X R&D Projects: GA ČR(CZ) GA14-33733S Institutional support: RVO:60077344 Keywords : Lepidoptera * ultraviolet reflectance * mimicry Subject RIV: EH - Ecology, Behaviour Impact factor: 1.601, year: 2016

  10. Characterization of ethanol concentrations at ultraviolet wavelength ...

    African Journals Online (AJOL)

    This paper presents the measurement of optical absorption spectrum for different concentrations of ethanol at ultraviolet wavelength. Ethanol absorption spectrum was measured using portable spectroscopy setup from Avantes. It consists of Balanced Deuterium Halogen light source and spectrometer. The light source can ...

  11. Ultraviolet spectra of Mg in liquid helium

    International Nuclear Information System (INIS)

    Moriwaki, Y.; Morita, N.

    1999-01-01

    Emission and absorption spectra of Mg atoms implanted in liquid helium have been observed in the ultraviolet region. We have presented a model of exciplex formation of Mg-He 10 and found that this model is more suitable for understanding the dynamics in the 3s3p 1 P→3s 21 S transition than the bubble model. (orig.)

  12. Combined ultraviolet studies of astronomical sources

    Science.gov (United States)

    Baliunas, S. L.; Dupree, A. K.; Elvis, M.; Huchra, J. P.; Kenyon, S.; Raymond, J. C.

    1986-01-01

    Topics addressed include: Cygnus Loop; P Cygni profiles in dwarf novae; YY Gem; nova shells; HZ Herculis; activity cycles in cluster giants; Alpha Ori; metal deficient giant stars; ultraviolet spectra of symbiotic stars detected by the Very Large Array; time variability in symbiotic stars; blue galaxies; and quasistellar objects with X-ray spectra.

  13. The impact of ultraviolet radiation on timber

    International Nuclear Information System (INIS)

    Dawson, B.

    1993-01-01

    Photochemical degradation of timber, the outcome of exposure of timber to ultraviolet radiation, is a light induced chemical and physical decay. Timber is a collection of dead wood cells. Impacts of radiation on the growing tree are therefore outside the scope of this paper, which is primarily concerned with timber as a material. (author). 5 refs. 2 figs

  14. 21 CFR 878.4635 - Ultraviolet lamp for tanning.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultraviolet lamp for tanning. 878.4635 Section 878... tanning. (a) Identification. An ultraviolet lamp for tanning is a device that is a lamp (including a fixture) intended to provide ultraviolet radiation to tan the skin. See § 1040.20 of this chapter. (b...

  15. 21 CFR 880.6710 - Medical ultraviolet water purifier.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical ultraviolet water purifier. 880.6710... Miscellaneous Devices § 880.6710 Medical ultraviolet water purifier. (a) Identification. A medical ultraviolet water purifier is a device intended for medical purposes that is used to destroy bacteria in water by...

  16. Comparison of solar photospheric bright points between Sunrise observations and MHD simulations

    Science.gov (United States)

    Riethmüller, T. L.; Solanki, S. K.; Berdyugina, S. V.; Schüssler, M.; Martínez Pillet, V.; Feller, A.; Gandorfer, A.; Hirzberger, J.

    2014-08-01

    Bright points (BPs) in the solar photosphere are thought to be the radiative signatures (small-scale brightness enhancements) of magnetic elements described by slender flux tubes or sheets located in the darker intergranular lanes in the solar photosphere. They contribute to the ultraviolet (UV) flux variations over the solar cycle and hence may play a role in influencing the Earth's climate. Here we aim to obtain a better insight into their properties by combining high-resolution UV and spectro-polarimetric observations of BPs by the Sunrise Observatory with 3D compressible radiation magnetohydrodynamical (MHD) simulations. To this end, full spectral line syntheses are performed with the MHD data and a careful degradation is applied to take into account all relevant instrumental effects of the observations. In a first step it is demonstrated that the selected MHD simulations reproduce the measured distributions of intensity at multiple wavelengths, line-of-sight velocity, spectral line width, and polarization degree rather well. The simulated line width also displays the correct mean, but a scatter that is too small. In the second step, the properties of observed BPs are compared with synthetic ones. Again, these are found to match relatively well, except that the observations display a tail of large BPs with strong polarization signals (most likely network elements) not found in the simulations, possibly due to the small size of the simulation box. The higher spatial resolution of the simulations has a significant effect, leading to smaller and more numerous BPs. The observation that most BPs are weakly polarized is explained mainly by the spatial degradation, the stray light contamination, and the temperature sensitivity of the Fe i line at 5250.2 Å. Finally, given that the MHD simulations are highly consistent with the observations, we used the simulations to explore the properties of BPs further. The Stokes V asymmetries increase with the distance to the

  17. Classical ultraviolet photoelectron spectroscopy of polymers

    International Nuclear Information System (INIS)

    Salaneck, W.R.

    2009-01-01

    Although X-ray photoelectron spectroscopy of polymers was well established by Clark and coworkers in the 1970s, ultraviolet photoelectron spectroscopy of polymer films, was developed later. Previous to the 1970s, the first attempts to use ultraviolet light on polymer films took the form of appearance potential (valence band edge) measurements. Only some years later could the full valence band region of thin polymer films, including insulating polymers, semiconducting polymers and electrically conducting polymers. The development of what might be termed 'classical ultraviolet photoelectron spectroscopy' of polymer films may be loosely based upon a variety of issues, including adapting thin polymer film technology to ultra high vacuum studies, the widespread use of helium resonance lamps for studies of solid surfaces, the combined advent of practical and sufficient theoretical-computational methods. The advent of, and the use of, easily available synchrotron radiation for multi-photon spectroscopies, nominally in the area of the near UV, is not included in the term 'classical'. At the same time, electrically conducting polymers were discovered, leading to applications of the corresponding semiconducting polymers, which added technologically driven emphasis to this development of ultraviolet photoelectron spectroscopy for polymer materials. This paper traces a limited number of highlights in the evolution of ultraviolet photoelectron spectroscopy of polymers, from the 1970s through to 2008. Also, since this issue is dedicated to Prof. Kazuhiko Seki, who has been a friend and competitor for over two decades, the author relies on some of Prof. Seki's earlier research, unpublished, on who-did-what-first. Prof. Seki's own contributions to the field, however, are discussed in other articles in this issue.

  18. THE BRIGHTEST OF REIONIZING GALAXIES SURVEY: CONSTRAINTS ON THE BRIGHT END OF THE z {approx} 8 LUMINOSITY FUNCTION

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, L. D.; Stiavelli, M.; Pirzkal, N. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Trenti, M. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Oesch, P. A. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Treu, T. [Department of Physics, University of California, Santa Barbara, CA 93106-9530 (United States); Bouwens, R. J. [Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands); Shull, J. M. [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); Holwerda, B. W. [European Space Agency (ESTEC), Keplerlaan 1, NL-2200 AG, Noordwijk (Netherlands)

    2012-12-01

    We report the discovery of 33 Lyman-break galaxy candidates at z {approx} 8 detected in Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging as part of the Brightest of Reionizing Galaxies (BoRG) pure-parallel survey. The ongoing BoRG survey currently has the largest area (274 arcmin{sup 2}) with Y {sub 098} (or Y {sub 105}), J {sub 125}, and H {sub 160} band coverage needed to search for z {approx} 8 galaxies, about three times the current CANDELS area, and slightly larger than what will be the final CANDELS wide component with Y {sub 105} data (required to select z {approx} 8 sources). Our sample of 33 relatively bright Y {sub 098}-dropout galaxies have J {sub 125}-band magnitudes between 25.5 and 27.4 mag. This is the largest sample of bright (J {sub 125} {approx}< 27.4) z {approx} 8 galaxy candidates presented to date. Combining our data set with the Hubble Ultra-Deep Field data set, we constrain the rest-frame ultraviolet galaxy luminosity function at z {approx} 8 over the widest dynamic range currently available. The combined data sets are well fitted by a Schechter function, i.e., {phi} (L) = {phi}{sub *} (L/L{sub *}){sup {alpha}} e{sup -(}L{sup /L{sub *})}, without evidence for an excess of sources at the bright end. At 68% confidence, for h = 0.7 we derive {phi}{sub *} = (4.3{sup +3.5} {sub -2.1}) Multiplication-Sign 10{sup -4} Mpc{sup -3}, M {sub *} = -20.26{sup +0.29} {sub -0.34}, and a very steep faint-end slope {alpha} = -1.98{sup +0.23} {sub -0.22}. While the best-fit parameters still have a strong degeneracy, especially between {phi}{sub *} and M {sub *}, our improved coverage at the bright end has reduced the uncertainty of the faint-end power-law slope at z {approx} 8 compared to the best previous determination at {+-}0.4. With a future expansion of the BoRG survey, combined with planned ultradeep WFC3/IR observations, it will be possible to further reduce this uncertainty and clearly demonstrate the steepening of the faint-end slope compared

  19. Improving the laser brightness of a commercial laser system

    Science.gov (United States)

    Naidoo, Darryl; Litvin, Igor; Forbes, Andrew

    2016-02-01

    We investigate the selection of a flat-top beam and a Gaussian beam inside a laser cavity on opposing mirrors. The concept is tested external to the laser cavity in a single pass and double pass regime where the latter mimics a single round trip in the laser. We implement this intra-cavity selection through the use of two 16 level diffractive optical elements. We consider a solid-state diode side-pumped laser resonator in a typical commercial laser configuration that consists of two planar mirrors where the DOEs are positioned at the mirrors. We out couple the Gaussian and flat-top distributions and we show that we improve the brightness of the laser with active mode control. We also demonstrate that the quality of the beam transformations determine the brightness improvement.

  20. Modeling laser brightness from cross Porro prism resonators

    Science.gov (United States)

    Forbes, Andrew; Burger, Liesl; Litvin, Igor Anatolievich

    2006-08-01

    Laser brightness is a parameter often used to compare high power laser beam delivery from various sources, and incorporates both the power contained in the particular mode, as well as the propagation of that mode through the beam quality factor, M2. In this study a cross Porro prism resonator is considered; crossed Porro prism resonators have been known for some time, but until recently have not been modeled as a complete physical optics system that allows the modal output to be determined as a function of the rotation angle of the prisms. In this paper we consider the diffraction losses as a function of the prism rotation angle relative to one another, and combine this with the propagation of the specific modes to determine the laser output brightness as a function of the prism orientation.

  1. Optical Observations of X-ray Bright, Optically Normal Galaxies

    Science.gov (United States)

    Sadun, Alberto C.; Aryan, N. S.; Ghosh, K. K.

    2007-05-01

    X-ray bright, optically normal galaxies (XBONGs) are galaxies that seem to have normal spectra and morphology, but are relatively bright x-ray sources. The large ratio of the x-ray to optical emission suggests that some activity, similar to that of active galactic nuclei (AGN), is occurring. Since the galaxies do not show any obvious sign of nuclear activity in their optical spectra, one possible explanation is that these galaxies do not have an optically thick accretion disk at small radii, as previously assumed. Previous data for NGC 7626 classifies it as an XBONG, and so we are studying optical features of this galaxy in order to determine better its features. After confirming an x-ray jet, we are now comparing this to optical features that we have found, including warped dust lanes and a possible optical jet.

  2. Large-scale brightness inhomogeneities in the solar atmosphere

    International Nuclear Information System (INIS)

    Mitchell, W.E. Jr.

    1982-01-01

    The intensity residuals are analyzed from a series of solar limb-darkening measurements in the wavelength range 5656 to 2997 A. The lengths of residual strings of the same sign exceed expectation by several orders of magnitude. The power spectrum fo the residuals shows a weak excess around 6000 km. For further study the 34000 limb-darkening residuals are subdivided into 5100 bright and faint cells. The frequency distribution of cell sizes peaks around 4500 km and increases from center to limb, the faint cells showing the greater center-limb effect. The cells are also studied as to contrast. A synoptic view indicates that only 12% of the cells are identifiable after a half hour. Phenomena that may combine to produce the observed wide spectrum of brightness inhomogeneities are briefly discussed. (orig.)

  3. Recent advances in high-brightness electron guns at AES

    International Nuclear Information System (INIS)

    Bluem, H.; Todd, A.M.M.; Cole, M.D.; Rathke, J.; Schultheiss, T.

    2003-01-01

    We describe a number of active Advanced Energy Systems projects pertaining to the development of advanced, high-brightness electron guns for various applications. These projects include a fully superconducting, CW RF gun, nearing test, that utilizes the niobium surface as the photocathode material. An integrated 100 mA, low emittance DC/SRF gun, ideal as an injector for ERL-type light sources and intended as the injector for a 100 kW FEL, is in late design stage. A parallel high-power, CW, normal-conducting L-band RF gun project has just begun. The early performance analysis for this gun also shows good promise as an injector for ERL-type light sources. Lastly, a fully axisymmetric RF gun, operating in X-band, is being studied as a source of extremely bright electron bunches

  4. Bright breathers in nonlinear left-handed metamaterial lattices

    Science.gov (United States)

    Koukouloyannis, V.; Kevrekidis, P. G.; Veldes, G. P.; Frantzeskakis, D. J.; DiMarzio, D.; Lan, X.; Radisic, V.

    2018-02-01

    In the present work, we examine a prototypical model for the formation of bright breathers in nonlinear left-handed metamaterial lattices. Utilizing the paradigm of nonlinear transmission lines, we build a relevant lattice and develop a quasi-continuum multiscale approximation that enables us to appreciate both the underlying linear dispersion relation and the potential for bifurcation of nonlinear states. We focus here, more specifically, on bright discrete breathers which bifurcate from the lower edge of the linear dispersion relation at wavenumber k=π . Guided by the multiscale analysis, we calculate numerically both the stable inter-site centered and the unstable site-centered members of the relevant family. We quantify the associated stability via Floquet analysis and the Peierls-Nabarro barrier of the energy difference between these branches. Finally, we explore the dynamical implications of these findings towards the potential mobility or lack thereof (pinning) of such breather solutions.

  5. Quantitative Image Restoration in Bright Field Optical Microscopy.

    Science.gov (United States)

    Gutiérrez-Medina, Braulio; Sánchez Miranda, Manuel de Jesús

    2017-11-07

    Bright field (BF) optical microscopy is regarded as a poor method to observe unstained biological samples due to intrinsic low image contrast. We introduce quantitative image restoration in bright field (QRBF), a digital image processing method that restores out-of-focus BF images of unstained cells. Our procedure is based on deconvolution, using a point spread function modeled from theory. By comparing with reference images of bacteria observed in fluorescence, we show that QRBF faithfully recovers shape and enables quantify size of individual cells, even from a single input image. We applied QRBF in a high-throughput image cytometer to assess shape changes in Escherichia coli during hyperosmotic shock, finding size heterogeneity. We demonstrate that QRBF is also applicable to eukaryotic cells (yeast). Altogether, digital restoration emerges as a straightforward alternative to methods designed to generate contrast in BF imaging for quantitative analysis. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  6. Very bright, near-infrared single photon emitters in diamond

    Directory of Open Access Journals (Sweden)

    D. W. M. Lau

    2013-09-01

    Full Text Available We demonstrate activation of bright diamond single photon emitters in the near infrared range by thermal annealing alone, i.e., without ion implantation. The activation is crucially dependent on the annealing ambient. The activation of the single photon emitters is only observed when the sample is annealed in forming gas (4% H2 in Ar above temperatures of 1000 °C. By contrast, no emitters are activated by annealing in vacuum, oxygen, argon or deuterium. The emitters activated by annealing in forming gas exhibit very bright emission in the 730-760 nm wavelength range and have linewidths of ∼1.5-2.5 nm at room temperature.

  7. High-brightness tapered laser diodes with photonic crystal structures

    Science.gov (United States)

    Li, Yi; Du, Weichuan; Kun, Zhou; Gao, Songxin; Ma, Yi; Tang, Chun

    2018-02-01

    Beam quality of tapered laser diodes is limited by higher order lateral mode. On purpose of optimizing the brightness of tapered laser diodes, we developed a novel design of tapered diodes. This devices based on InGaAs/AlGaAs asymmetry epitaxial structure, containing higher order lateral mode filtering schemes especially photonic crystal structures, which fabricated cost effectively by using standard photolithography and dry etch processes. Meanwhile, the effects of photonic crystal structures on mode control are also investigated theoretically by FDBPM (Finite-Difference Beam Propagation Method) calculation. We achieved a CW optical output power of 6.9W at 940nm for a single emitter with 4 mm cavity length. A nearly diffraction limited beam of M2 ≍1.9 @ 0.5W has been demonstrated, and a highest brightness of β =75MW/(cm2 ·sr) was reached.

  8. Using RSpec in an introductory bright star spectroscopy lab activity

    Science.gov (United States)

    Howe, James; Sitar, David J.

    2018-01-01

    After presenting at the North Carolina Section of the American Association of Physics Teachers during the fall 2016 meeting, we were encouraged to turn our poster into a paper. This article describes the strengthening of a bright star spectroscopy lab activity for introductory astronomy lab students (AST1002) at Appalachian State University. Explanations of the tools and methods used in the activity are included, particularly the preparation of additional materials using RSpec and calibrated instrument response curves.

  9. Manakins can produce iridescent and bright feather colours without melanosomes.

    Science.gov (United States)

    Igic, Branislav; D'Alba, Liliana; Shawkey, Matthew D

    2016-06-15

    Males of many species often use colourful and conspicuous ornaments to attract females. Among these, male manakins (family: Pipridae) provide classic examples of sexual selection favouring the evolution of bright and colourful plumage coloration. The highly iridescent feather colours of birds are most commonly produced by the periodic arrangement of melanin-containing organelles (melanosomes) within barbules. Melanin increases the saturation of iridescent colours seen from optimal viewing angles by absorbing back-scattered light; however, this may reduce the wide-angle brightness of these signals, contributing to a dark background appearance. We examined the nanostructure of four manakin species (Lepidothrix isidorei, L. iris, L. nattereri and L. coeruleocapilla) to identify how they produce their bright plumage colours. Feather barbs of all four species were characterized by dense and fibrous internal spongy matrices that likely increase scattering of light within the barb. The iridescent, yet pale or whitish colours of L. iris and L. nattereri feathers were produced not by periodically arranged melanosomes within barbules, but by periodic matrices of air and β-keratin within barbs. Lepidothrix iris crown feathers were able to produce a dazzling display of colours with small shifts in viewing geometry, likely because of a periodic nanostructure, a flattened barb morphology and disorder at a microstructural level. We hypothesize that iridescent plumage ornaments of male L. iris and L. nattereri are under selection to increase brightness or luminance across wide viewing angles, which may potentially increase their detectability by females during dynamic and fast-paced courtship displays in dim light environments. © 2016. Published by The Company of Biologists Ltd.

  10. Thoughts About Nursing Curricula: Dark Clouds and Bright Lights.

    Science.gov (United States)

    Turkel, Marian C; Fawcett, Jacqueline; Amankwaa, Linda; Clarke, Pamela N; Dee, Vivien; Eustace, Rosemary; Hansell, Phyllis Shanley; Jones, Dorothy A; Smith, Marlaine C; Zahourek, Rothlyn

    2018-04-01

    In this essay, several nurse scholars who are particularly concerned about the contemporary state of nursing science present their concerns about the inclusion of nursing conceptual models and theories in the curricula of nursing programs (dark clouds) and ways in which the concerns have been addressed (bright lights). This essay is the second of two essays that were catalyzed by Barrett's paper, "Again, What Is Nursing Science?" The first essay was published in the previous issue of Nursing Science Quarterly.

  11. Human Adolescent Phase Response Curves to Bright White Light.

    Science.gov (United States)

    Crowley, Stephanie J; Eastman, Charmane I

    2017-08-01

    Older adolescents are particularly vulnerable to circadian misalignment and sleep restriction, primarily due to early school start times. Light can shift the circadian system and could help attenuate circadian misalignment; however, a phase response curve (PRC) to determine the optimal time for receiving light and avoiding light is not available for adolescents. We constructed light PRCs for late pubertal to postpubertal adolescents aged 14 to 17 years. Participants completed 2 counterbalanced 5-day laboratory sessions after 8 or 9 days of scheduled sleep at home. Each session included phase assessments to measure the dim light melatonin onset (DLMO) before and after 3 days of free-running through an ultradian light-dark (wake-sleep) cycle (2 h dim [~20 lux] light, 2 h dark). In one session, intermittent bright white light (~5000 lux; four 20-min exposures) was alternated with 10 min of dim room light once per day for 3 consecutive days. The time of light varied among participants to cover the 24-h day. For each individual, the phase shift to bright light was corrected for the free-run derived from the other laboratory session with no bright light. One PRC showed phase shifts in response to light start time relative to the DLMO and another relative to home sleep. Phase delay shifts occurred around the hours corresponding to home bedtime. Phase advances occurred during the hours surrounding wake time and later in the afternoon. The transition from delays to advances occurred at the midpoint of home sleep. The adolescent PRCs presented here provide a valuable tool to time bright light in adolescents.

  12. High-brightness switchable multiwavelength remote laser in air

    Energy Technology Data Exchange (ETDEWEB)

    Yao Jinping; Cheng Ya; Xu Zhizhan [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Zeng Bin; Li Guihua; Chu Wei; Ni Jielei; Zhang Haisu [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of Chinese Academy of Sciences, Beijing 100080 (China); Xu Huailiang [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Chin, See Leang [Center for Optics, Universite Laval, Quebec City, Quebec G1V 0A6 (Canada)

    2011-11-15

    We demonstrate a harmonic-seeded switchable multiwavelength laser in air driven by intense midinfrared femtosecond laser pulses, in which population inversion occurs at an ultrafast time scale (i.e., less than {approx}200 fs) owing to direct formation of excited molecular nitrogen ions by strong-field ionization of inner-valence electrons. The bright multiwavelength laser in air opens the perspective for remote detection of multiple pollutants based on nonlinear optical spectroscopy.

  13. Very bright optical transient near the Trifid and Lagoon Nebulae

    Science.gov (United States)

    Dunsby, Peter

    2018-03-01

    Peter Dunsby (University of Cape Town) reports the detection of a very bright optical transient in the region between the Lagoon and Trifid Nebulae based on observations obtained from Cape Town on 20 March 2018, between 01:00 and 03:45 UT. The object was visible throughout the full duration of the observations and not seen when this field was observed previously (08 March 2018).

  14. Bright spots among the world’s coral reefs

    Science.gov (United States)

    Cinner, Joshua E.; Huchery, Cindy; MacNeil, M. Aaron; Graham, Nicholas A. J.; McClanahan, Tim R.; Maina, Joseph; Maire, Eva; Kittinger, John N.; Hicks, Christina C.; Mora, Camilo; Allison, Edward H.; D'Agata, Stephanie; Hoey, Andrew; Feary, David A.; Crowder, Larry; Williams, Ivor D.; Kulbicki, Michel; Vigliola, Laurent; Wantiez, Laurent; Edgar, Graham; Stuart-Smith, Rick D.; Sandin, Stuart A.; Green, Alison L.; Hardt, Marah J.; Beger, Maria; Friedlander, Alan; Campbell, Stuart J.; Holmes, Katherine E.; Wilson, Shaun K.; Brokovich, Eran; Brooks, Andrew J.; Cruz-Motta, Juan J.; Booth, David J.; Chabanet, Pascale; Gough, Charlie; Tupper, Mark; Ferse, Sebastian C. A.; Sumaila, U. Rashid; Mouillot, David

    2016-07-01

    Ongoing declines in the structure and function of the world’s coral reefs require novel approaches to sustain these ecosystems and the millions of people who depend on them. A presently unexplored approach that draws on theory and practice in human health and rural development is to systematically identify and learn from the ‘outliers’—places where ecosystems are substantially better (‘bright spots’) or worse (‘dark spots’) than expected, given the environmental conditions and socioeconomic drivers they are exposed to. Here we compile data from more than 2,500 reefs worldwide and develop a Bayesian hierarchical model to generate expectations of how standing stocks of reef fish biomass are related to 18 socioeconomic drivers and environmental conditions. We identify 15 bright spots and 35 dark spots among our global survey of coral reefs, defined as sites that have biomass levels more than two standard deviations from expectations. Importantly, bright spots are not simply comprised of remote areas with low fishing pressure; they include localities where human populations and use of ecosystem resources is high, potentially providing insights into how communities have successfully confronted strong drivers of change. Conversely, dark spots are not necessarily the sites with the lowest absolute biomass and even include some remote, uninhabited locations often considered near pristine. We surveyed local experts about social, institutional, and environmental conditions at these sites to reveal that bright spots are characterized by strong sociocultural institutions such as customary taboos and marine tenure, high levels of local engagement in management, high dependence on marine resources, and beneficial environmental conditions such as deep-water refuges. Alternatively, dark spots are characterized by intensive capture and storage technology and a recent history of environmental shocks. Our results suggest that investments in strengthening fisheries

  15. The quiet Sun brightness temperature at 408 MHz

    International Nuclear Information System (INIS)

    Avignon, Y.; Lantos, P.; Palagi, F.; Patriarchi, P.

    1975-01-01

    The flux of the radio quiet Sun and the brightness temperature at 408 MHz (73cm) are derived from measurements with the E-W Nancay interferometer and the E-W arm of the Medicina North Cross. It is shown that the lowest envelopes, which defined the radio quiet Sun, correspond to transits of extended coronal holes across the disk of the Sun. (Auth.)

  16. Brightness/darkness induction and the genesis of a contour

    Directory of Open Access Journals (Sweden)

    Sergio eRoncato

    2014-10-01

    Full Text Available Visual contours often result from the integration or interpolation of fragmented edges.The strength of the completion increases when the edges share the same contrast polarity (CP. Here we demonstrate that the appearance in the perceptual field of this integrated unit, or contour of invariant CP, is concomitant with a vivid brightness alteration of the surfaces at its opposite sides. To observe this effect requires some stratagems because the formation in the visual field of a contour of invariant CP normally engenders the formation of a second contour and then the rise of two streams of induction signals that interfere in different ways. Particular configurations have been introduced that allow us to observe the induction effects of one contour taken in isolation. I documented these effects by phenomenological observations and psychophysical measurement of the brightness alteration in relation to luminance contrast. When the edges of the same CP complete to form a contour, the background of homogeneous luminance appears to dim at one side and to brighten at the opposite side (in accord with the CP. The strength of the phenomenon is proportional to the local luminance contrast. This effect weakens or nulls when the contour of the invariant CP separates surfaces filled with different grey shades.These conflicting results stimulate a deeper exploration of the induction phenomena and their role in the computation of brightness contrast. An alternative perspective is offered to account for some brightness illusions and their relation to the phenomenal transparency. The main assumption asserts that, when in the same region induction signals of opposite CP overlap, the filling-in are blocked unless the image is stratified into different layers, one for each signal of the same polarity. Phenomenological observations document this solution by the visual system

  17. Bright triplet excitons in caesium lead halide perovskites

    Science.gov (United States)

    Becker, Michael A.; Vaxenburg, Roman; Nedelcu, Georgian; Sercel, Peter C.; Shabaev, Andrew; Mehl, Michael J.; Michopoulos, John G.; Lambrakos, Samuel G.; Bernstein, Noam; Lyons, John L.; Stöferle, Thilo; Mahrt, Rainer F.; Kovalenko, Maksym V.; Norris, David J.; Rainò, Gabriele; Efros, Alexander L.

    2018-01-01

    Nanostructured semiconductors emit light from electronic states known as excitons. For organic materials, Hund’s rules state that the lowest-energy exciton is a poorly emitting triplet state. For inorganic semiconductors, similar rules predict an analogue of this triplet state known as the ‘dark exciton’. Because dark excitons release photons slowly, hindering emission from inorganic nanostructures, materials that disobey these rules have been sought. However, despite considerable experimental and theoretical efforts, no inorganic semiconductors have been identified in which the lowest exciton is bright. Here we show that the lowest exciton in caesium lead halide perovskites (CsPbX3, with X = Cl, Br or I) involves a highly emissive triplet state. We first use an effective-mass model and group theory to demonstrate the possibility of such a state existing, which can occur when the strong spin-orbit coupling in the conduction band of a perovskite is combined with the Rashba effect. We then apply our model to CsPbX3 nanocrystals, and measure size- and composition-dependent fluorescence at the single-nanocrystal level. The bright triplet character of the lowest exciton explains the anomalous photon-emission rates of these materials, which emit about 20 and 1,000 times faster than any other semiconductor nanocrystal at room and cryogenic temperatures, respectively. The existence of this bright triplet exciton is further confirmed by analysis of the fine structure in low-temperature fluorescence spectra. For semiconductor nanocrystals, which are already used in lighting, lasers and displays, these excitons could lead to materials with brighter emission. More generally, our results provide criteria for identifying other semiconductors that exhibit bright excitons, with potential implications for optoelectronic devices.

  18. Bright to Dim Oscillatory Response of the Neurospora Circadian Oscillator

    OpenAIRE

    Gooch, Van D.; Johnson, Alicia E.; Larrondo, Luis F.; Loros, Jennifer J.; Dunlap, Jay C.

    2014-01-01

    The fungus Neurospora crassa constitutes an important model system extensively used in chronobiology. Several studies have addressed how environmental cues, such as light, can reset or synchronize a circadian system. By means of an optimized firefly luciferase reporter gene and a controllable lighting system, we show that Neurospora can display molecular circadian rhythms in dim light when cultures receive bright light prior to entering dim light conditions. We refer to this behavior as the “...

  19. Low-Surface-Brightness Galaxies: Hidden Galaxies Revealed

    Science.gov (United States)

    Bothun, G.; Impey, C.; McGaugh, S.

    1997-07-01

    In twenty years, low surface brightness (LSB) galaxies have evolved from being an idiosyncratic notion to being one of the major baryonic repositories in the Universe. The story of their discovery and the characterization of their properties is told here. Their recovery from the noise of the night sky background is a strong testament to the severity of surface brightness selection effects. LSB galaxies have a number of remarkable properties which distinguish them from the more familiar Hubble Sequence of spirals. The two most important are 1) they evolve at a significantly slower rate and may well experience star formation outside of the molecular cloud environment, 2) they are embedded in dark matter halos which are of lower density and more extended than the halos around high surface brightness (HSB) disk galaxies. Compared to HSB disks, LSB disks are strongly dark matter dominated at all radii and show a systematic increase in $M/L$ with decreasing central surface brightness. In addition, the recognition that large numbers of LSB galaxies actually exist has changed the form of the galaxy luminosity function and has clearly increased the space density of galaxies at z =0. Recent CCD surveys have uncovered a population of red LSB disks that may be related to the excess of faint blue galaxies detected at moderate redshifts. LSB galaxies offer us a new window into galaxy evolution and formation which is every bit as important as those processes which have produced easy to detect galaxies. Indeed, the apparent youth of some LSB galaxies suggest that galaxy formation is a greatly extended process. While the discovery of LSB galaxies have lead to new insights, it remains unwise to presume that we now have a representative sample which encompasses all galaxy types and forms. (SECTION: Invited Review Paper)

  20. Near-Real-Time DMSP SSM/I-SSMIS Daily Polar Gridded Brightness Temperatures

    Data.gov (United States)

    National Aeronautics and Space Administration — The Near-Real-Time DMSP SSM/I-SSMIS Daily Polar Gridded Brightness Temperature product provides near-real-time brightness temperatures for both the Northern and...

  1. On correct evaluation techniques of brightness enhancement effect measurement data

    Science.gov (United States)

    Kukačka, Leoš; Dupuis, Pascal; Motomura, Hideki; Rozkovec, Jiří; Kolář, Milan; Zissis, Georges; Jinno, Masafumi

    2017-11-01

    This paper aims to establish confidence intervals of the quantification of brightness enhancement effects resulting from the use of pulsing bright light. It is found that the methods used so far may yield significant bias in the published results, overestimating or underestimating the enhancement effect. The authors propose to use a linear algebra method called the total least squares. Upon an example dataset, it is shown that this method does not yield biased results. The statistical significance of the results is also computed. It is concluded over an observation set that the currently used linear algebra methods present many patterns of noise sensitivity. Changing algorithm details leads to inconsistent results. It is thus recommended to use the method with the lowest noise sensitivity. Moreover, it is shown that this method also permits one to obtain an estimate of the confidence interval. This paper neither aims to publish results about a particular experiment nor to draw any particular conclusion about existence or nonexistence of the brightness enhancement effect.

  2. Bright Soil Churned by Spirit's Sol 1861 Drive

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Spirit drove 22.7 meters (74 feet) toward the southwest on the 1,861st Martian day, or sol, of Spirit's mission on Mars (March 28, 2009). After the drive, the rover took this image with its front hazard-avoidance camera, looking back at the tracks from the drive. As usual since losing the use of its right-front wheel in 2006, Spirit drove backwards. The immobile right-front wheel churned up a long stripe of bright soil during this drive. Where Spirit has found such bright soil in the past, subsequent analysis of the composition found concentrations of sulfur or silica that testified to past action of water at the site. When members of the rover team saw the large quantity of bright soil exposed by the Sol 1861 drive, they quickly laid plans to investigate the composition with Spirit's alpha particle X-ray spectrometer. The Sol 1861 drive took the rover past the northwest corner of the low plateau called 'Home Plate,' making progress on a route around the western side of Home Plate. The edge of Home Plate forms the horizon on the right side of this image. Husband Hill is on the horizon on the left side. For scale, the parallel rover wheel tracks are about 1 meter (40 inches) apart. The rover's hazard-avoidance cameras take 'fisheye' wide-angle images.

  3. Inversion methods for analysis of neutron brightness measurements in tokamaks

    International Nuclear Information System (INIS)

    Gorini, G.; Gottardi, N.

    1990-02-01

    The problem of determining neutron emissivity from neutron brightness measurements in magnetic fusion plasmas is addressed. In the case of two-dimensional measurements with two orthogonal cameras, a complete, tomographic analysis of the data can in principle be performed. The results depend critically on the accuracy of the measurements and alternative solutions can be sought under the assumption of a known emissivity topology (Generalized Abel Inversion). In this work, neutron brightness data from the JET tokamak have been studied with both methods. We find that with the present experimental uncertainty (levels 10-20%) the Abel inversion method works best, while two-dimensional information cannot in general be deduced. This is confirmed by studies of the error propagation in the inversion using artificial data, which are also presented here. An important application of emissivity profile information is the determination of the plasma deuterium temperature profile, T D (R). Results are presented here from the analysis of JET data and the errors in T D (R) are discussed in some detail. It is found that, for typical JET plasma conditions, the dominant source of uncertainty arises from the high plasma impurity level and the fact that it is poorly known; these problems can be expected to be remedied and neutron brightness measurements would be expected to be very effective (especially in high density plasmas) as a T D (R) diagnostics. (author)

  4. SMOS brightness temperature assimilation into the Community Land Model

    Directory of Open Access Journals (Sweden)

    D. Rains

    2017-11-01

    Full Text Available SMOS (Soil Moisture and Ocean Salinity mission brightness temperatures at a single incident angle are assimilated into the Community Land Model (CLM across Australia to improve soil moisture simulations. Therefore, the data assimilation system DasPy is coupled to the local ensemble transform Kalman filter (LETKF as well as to the Community Microwave Emission Model (CMEM. Brightness temperature climatologies are precomputed to enable the assimilation of brightness temperature anomalies, making use of 6 years of SMOS data (2010–2015. Mean correlation R with in situ measurements increases moderately from 0.61 to 0.68 (11 % for upper soil layers if the root zone is included in the updates. A reduced improvement of 5 % is achieved if the assimilation is restricted to the upper soil layers. Root-zone simulations improve by 7 % when updating both the top layers and root zone, and by 4 % when only updating the top layers. Mean increments and increment standard deviations are compared for the experiments. The long-term assimilation impact is analysed by looking at a set of quantiles computed for soil moisture at each grid cell. Within hydrological monitoring systems, extreme dry or wet conditions are often defined via their relative occurrence, adding great importance to assimilation-induced quantile changes. Although still being limited now, longer L-band radiometer time series will become available and make model output improved by assimilating such data that are more usable for extreme event statistics.

  5. Three Bright X-ray Sources in NGC 1313

    Science.gov (United States)

    Colbert, E.; Petre, R.; Schlegel, E.

    1992-12-01

    Three bright X-ray sources were detected in a recent (April/May 1991) ROSAT PSPC observation of the nearby (D ~ 4.5 Mpc) face--on barred spiral galaxy NGC 1313. Two of the sources were at positions coincident with X-ray sources detected by Fabbiano & Trinchieri (ApJ 315, 1987) in a previous (Jan 1980) Einstein IPC observation. The position of the brightest Einstein source is near the center of NGC 1313, and the second Einstein source is ~ 7' south of the ``nuclear'' source, in the outskirts of the spiral arms. A third bright X-ray source was detected in the ROSAT observation ~ 7' southwest of the ``nuclear'' source. We present X-ray spectra and X-ray images for the three bright sources found in the ROSAT observation of NGC 1313, and compare with previous Einstein results. Spectral analysis of these sources require them to have very large soft X-ray luminosities ( ~ 10(40) erg s(-1) ) when compared with typical X-ray sources in our Galaxy. Feasible explanations for the X-ray emission are presented. The third X-ray source is positively identified with the recently discovered (Ryder et. al., ApJ 1992) peculiar type-II supernova 1978K.

  6. Ultraviolet continuum variability and visual flickering in the peculiar object MWC 560

    Science.gov (United States)

    Michalitsianos, A. G.; Perez, M.; Shore, S. N.; Maran, S. P.; Karovska, M.; Sonneborn, G.; Webb, J. R.; Barnes, Thomas G., III; Frueh, Marian L.; Oliversen, R. J.

    1993-01-01

    High-speed U-band photometry of the peculiar emission object MWC 560 obtained with the ground-based instrumentation, and V-band photometry obtained with the International Ultraviolet Explorer-Fine Error Sensor indicates irregular brightness variations are quasi-periodic. Multiple peaks of relative brightness power indicate statistically significant quasi periods existing in a range of 3-35 minutes, that are superposed on slower hourly varying components. We present a preliminary model that explains the minute and hourly time-scale variations in MWC 560 in terms of a velocity-shear instability that arises because a white dwarf magnetosphere impinges on an accretion disk. We also find evidence for Fe II multiplet pseudocontinuum absorption opacity in far-UV spectra of CH Cygni which is also present in MWC 560. Both CH Cyg and MWC 560 may be in an evolutionary stage that is characterized by strong UV continuum opacity which changes significantly during outburst, occurring before they permanently enter the symbiotic nebular emission phase.

  7. Effect of ultraviolet exposure on mitochondrial respiratory system

    Energy Technology Data Exchange (ETDEWEB)

    Noda, K [Kurume Univ., Fukuoka (Japan). School of Medicine

    1975-09-01

    To find the photodynamic effect of ultraviolet light on the mitochondrial respiratory chain, mitochondria were obtained from rat livers, and the suspension was exposed to an extensive ultraviolet light. The oxygen consumption was measured polarographically with a Clark oxygen electrode. The effect of ultraviolet exposure on the five states of respiratory control (Chance and Williams), the P/O ratio, and the respiratory control index in mitochondria was discussed. The ultraviolet light with a dose of 9.6 x 10/sup 6/ erg/cm/sup 2/ caused the oxidative phosphorylation in mitochondria to uncouple. The 2nd phosphorylation site of the respiratory chain was susceptible to ultraviolet exposure. The stimulation of latent ATPase activity in mitochondria following exposure was observed by increasing exposure of ultraviolet light. However, DNP-stimulated ATPase was found to be stable in activity. The uncoupling of the respiratory chain by ultraviolet exposure was not detected if the mitochondrial suspension was preincubated with bovine serum albumin before exposure. The changes in light absorption of the mitochondrial suspension were followed at 520 nm after exposure. A close correlation was found between the ultraviolet exposure and swelling in mitochondria. But, the reversing contraction was observed by adding ATP to the swelled mitochondria. The peroxide compound was formed in mitochondria irradiated with ultraviolet light. The amount of compounds formed was dependent on the radiant energy of ultraviolet light. The possible mechanisms involved in the photodynamic effect of ultraviolet light to the mitochondrial respiration system were discussed.

  8. The Physics and Applications of High Brightness Electron Beams

    Science.gov (United States)

    Palumbo, Luigi; Rosenzweig, J.; Serafini, Luca

    2007-09-01

    Plenary sessions. RF deflector based sub-Ps beam diagnostics: application to FEL and advanced accelerators / D. Alesini. Production of fermtosecond pulses and micron beam spots for high brightness electron beam applications / S.G. Anderson ... [et al.]. Wakefields of sub-picosecond electron bunches / K.L.F. Bane. Diamond secondary emitter / I. Ben-Zvi ... [et al.]. Parametric optimization for an X-ray free electron laser with a laser wiggler / R. Bonifacio, N. Piovella and M.M. Cola. Needle cathodes for high-brightness beams / C.H. Boulware ... [et al.]. Non linear evolution of short pulses in FEL cascaded undulators and the FEL harmonic cascade / L. Giannessi and P. Musumeci. High brightness laser induced multi-meV electron/proton sources / D. Giulietti ... [et al.]. Emittance limitation of a conditioned beam in a strong focusing FEL undulator / Z. Huang, G. Stupakov and S. Reiche. Scaled models: space-charge dominated electron storage rings / R.A. Kishek ... [et al.]. High brightness beam applications: energy recovered linacs / G.A. Krafft. Maximizing brightness in photoinjectors / C. Limborg-Deprey and H. Tomizawa. Ultracold electron sources / O.J. Luiten ... [et al.]. Scaling laws of structure-based optical accelerators / A. Mizrahi, V. Karagodsky and L. Schächter. High brightness beams-applications to free-electron lasers / S. Reiche. Conception of photo-injectors for the CTF3 experiment / R. Roux. Superconducting RF photoinjectors: an overview / J. Sekutowicz. Status and perspectives of photo injector developments for high brightness beams / F. Stephan. Results from the UCLA/FNLP underdense plasma lens experiment / M.C. Thompson ... [et al.]. Medical application of multi-beam compton scattering monochromatic tunable hard X-ray source / M. Uesaka ... [et al.]. Design of a 2 kA, 30 fs RF-photoinjector for waterbag compression / S.B. Van Der Geer, O.J. Luiten and M.J. De Loos. Proposal for a high-brightness pulsed electron source / M. Zolotorev ... [et al

  9. ULTRAVIOLET HALOS AROUND SPIRAL GALAXIES. I. MORPHOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Hodges-Kluck, Edmund; Cafmeyer, Julian; Bregman, Joel N., E-mail: hodgeskl@umich.edu [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)

    2016-12-10

    We examine ultraviolet halos around a sample of highly inclined galaxies within 25 Mpc to measure their morphology and luminosity. Despite contamination from galactic light scattered into the wings of the point-spread function, we find that ultraviolet (UV) halos occur around each galaxy in our sample. Around most galaxies the halos form a thick, diffuse disk-like structure, but starburst galaxies with galactic superwinds have qualitatively different halos that are more extensive and have filamentary structure. The spatial coincidence of the UV halos above star-forming regions, the lack of consistent association with outflows or extraplanar ionized gas, and the strong correlation between the halo and galaxy UV luminosity suggest that the UV light is an extragalactic reflection nebula. UV halos may thus represent 10{sup 6}–10{sup 7} M {sub ⊙} of dust within 2–10 kpc of the disk, whose properties may change with height in starburst galaxies.

  10. Contact lens disinfection by ultraviolet light

    International Nuclear Information System (INIS)

    Dolman, P.J.; Dobrogowski, M.J.

    1989-01-01

    A 253.7-nm ultraviolet light with an intensity of 1,100 microW/cm2 was tested for its germicidal activity against contact lenses and storage solutions contaminated with various corneal pathogens. The exposure time necessary to reduce a concentration of organisms from 10(6)/ml to less than 10/ml was 30 seconds for Staphylococcus aureus, 60 seconds for Pseudomonas aeruginosa, and 84 seconds for Candida albicans. The time necessary to sterilize a suspension of 10(4)/ml Acanthamoeba polyphaga was less than three minutes with this technique. Four brands of soft contact lenses were exposed to ultraviolet light for over eight hours without changing their appearance, comfort, or refraction

  11. Effective polycrystalline sensor of ultraviolet radiation

    Directory of Open Access Journals (Sweden)

    S.Yu. Pavelets

    2017-10-01

    Full Text Available Deposition of special thin layers with high and low resistance in space charge region of surface barrier photoconverters based on the p-Cu1.8S/n-CdS structure leads to a sufficient increase in photosensitivity and decrease in dark tunneling-recombination current. Highly efficient and stable polycrystalline photoconverters of ultraviolet radiation based on polycrystalline CdS have been obtained. Electrical and photoelectric properties have been investigated, and the main operational parameters of ultraviolet sensors have been adduced. The reasons for high stability of the parameters inherent to the p-Cu1.8S/n-CdS sensors are as follows: the absence of impurity components additionally doped to the barrier structure and stability of the photocurrent photoemission component.

  12. Subdwarf ultraviolet excesses and metal abundances

    International Nuclear Information System (INIS)

    Carney, B.W.

    1979-01-01

    The relation between stellar ultraviolet excesses and abundances is reexamined with the aid of new data, and an investigation is made of the accuracy of previous abundance analyses. A high-resolution echellogram of the subdwarf HD 201891 is analyzed to illustrate some of the problems. Generally, the earliest and latest analytical techniques yield consistent results for dwarfs. New UBV data yield normalized ultraviolet excesses, delta (U-B)/sub 0.6/, which are compared to abundances to produce a graphical relation that may be used to estimate [Fe/H] to +- 0.2 dex, given UBV colors accurate to +- 0.01 mag. The relation suggests a possible discontinuity between the halo and old-disk stars

  13. Cosmetic and medical applications of ultraviolet radiation

    International Nuclear Information System (INIS)

    Diffey, B.L.

    1987-01-01

    The social desirability of a tanned skin is apparent and many people associate a bronzed body with good health and a sense of well-being. In Northern Europe and America the lack of long periods of sunshine has led to the establishment of the suntanning industry where artificial sources of ultraviolet radiation emitting almost entirely in the UV-A region supplement sunlight exposure

  14. Ultraviolet stability in euclidean scalar field theories

    Energy Technology Data Exchange (ETDEWEB)

    Benfatto, G; Cassandro, M; Gallavotti, G; Nicolo, F; Olivieri, E; Presutti, E; Scacciatelli, E [Rome Univ. (Italy). Istituto di Matematica; Rome Univ. (Italy). Istituto di Fisica)

    1980-01-01

    We develop a technique for reducing the problem of the ultraviolet divergences and their removal to a free field problem. This work is an example of a problem to which a rather general method can be applied. It can be thought as an attempt towards a rigorous version (in 2 or 3 space-time dimensions) of the analysis of the structure of the functional integrals, the underlying mechanism being essentially the same as in Glimms approach.

  15. Ultraviolet signals in birds are special.

    OpenAIRE

    Hausmann, Franziska; Arnold, Kathryn E; Marshall, N Justin; Owens, Ian P F

    2003-01-01

    Recent behavioural experiments have shown that birds use ultraviolet (UV)-reflective and fluorescent plumage as cues in mate choice. It remains controversial, however, whether such UV signals play a special role in sexual communication, or whether they are part of general plumage coloration. We use a comparative approach to test for a general association between sexual signalling and either UV-reflective or fluorescent plumage. Among the species surveyed, 72% have UV colours and there is a si...

  16. Impurity study of TMX using ultraviolet spectroscopy

    International Nuclear Information System (INIS)

    Allen, S.L.; Strand, O.T.; Moos, H.W.; Fortner, R.J.; Nash, T.J.; Dietrich, D.D.

    1981-01-01

    An extreme ultraviolet (EUV) study of the emissions from intrinsic and injected impurities in TMX is presented. Two survey spectrographs were used to determine that the major impurities present were oxygen, nitrogen, carbon, and titanium. Three absolutely-calibrated monochromators were used to measure the time histories and radial profiles of these impurity emissions in the central cell and each plug. Two of these instruments were capable of obtaining radial profiles as a function of time in a single shot

  17. Minimal length uncertainty relation and ultraviolet regularization

    Science.gov (United States)

    Kempf, Achim; Mangano, Gianpiero

    1997-06-01

    Studies in string theory and quantum gravity suggest the existence of a finite lower limit Δx0 to the possible resolution of distances, at the latest on the scale of the Planck length of 10-35 m. Within the framework of the Euclidean path integral we explicitly show ultraviolet regularization in field theory through this short distance structure. Both rotation and translation invariance can be preserved. An example is studied in detail.

  18. The Ultraviolet Index: a useful tool.

    Science.gov (United States)

    Kinney, J P; Long, C S

    2000-09-01

    The Ultraviolet Index was developed in the United States in 1994 following successful use of ultraviolet (UV) alerts in other countries. This daily National Weather Service prediction is a calculation which integrates five data elements to yield the amount of UV radiation impacting the surface (1m2) at solar noon in 58 of the largest US population centers. This simple numeric prediction is then categorized by the Environmental Protection Agency into five "exposure levels" with protective actions recommended for each level. This information is disseminated through the media. Daily reminders seem to affect awareness and behavior in Canada, but US surveys indicate the need for better understanding through educational graphics. Comparing the UV Index to a precipitation prediction has merit in that it links a familiar daily prediction with implied appropriate protective measures. Graphics link the ideas that "when it rains it pours and when it shines it radiates." Beginning in schools, camps, and dermatology meetings, using the rain/shine analogy, a wider exposure to the Ultraviolet Index is proposed.

  19. Inhibition of seagrass photosynthesis by ultraviolet-B radiation

    International Nuclear Information System (INIS)

    Trocine, R.P.; Rice, J.D.; Wells, G.N.

    1981-01-01

    Effects of ultraviolet-B radiation on the photosynthesis of seagrasses (Halophila engelmanni Aschers, Halodule wrightii Aschers, and Syringodium filiforme (Kuetz) were examined. The intrinsic tolerance of each seagrass to ultraviolet-B, the presence and effectiveness of photorepair mechanisms to ultraviolet-B-induced photosynthetic inhibition, and the role of epiphytic growth as a shield from ultraviolet-B were investigated. Halodule was found to possess the greatest photosynthetic tolerance for ultraviolet-B. Photosynthesis in Syringodium was slightly more sensitive to ultraviolet-B while Halophila showed relatively little photosynthetic tolerance. Evidence for a photorepair mechanism was found only in Halodule. Syringodium appeared to rely primarily on a thick epidermal cell layer to reduce photosynthetic damage. Halophila seemed to have no morphological or photorepair capabilities to deal with ultraviolet-B. This species appeared to rely on epiphytic and detrital shielding and the shade provided by other seagrasses to reduce ultraviolet-B irradiation to tolerable levels. The presence of epiphytes on leaf surfaces was found to reduce the extent of photosynthetic inhibition from ultraviolet-B exposure in all species. Halophila appears to obtain an increased photosynthetic tolerance to ultraviolet-B as an indirect benefit of chloroplast clumping to avoid photo-oxidation by intense levels of photosynthetically active radiation

  20. Conversion from HST ACS and STIS auroral counts into brightness, precipitated power and radiated power for H2 giant planets

    Science.gov (United States)

    Gustin, J.; Bonfond, B.; Grodent, D.; Gerard, J. C.

    2012-09-01

    The STIS and ACS instruments onboard HST are widely used to study the giant planet's aurora. Several assumptions have to be made to convert the instrumental counts into meaningful physical values (type and bandwidth of the filters, definition of the physical units, etc…), but these may significantly differ from one author to another, which makes it difficult to compare the auroral characteristics published in different studies. We present a method to convert the counts obtained in representative ACS and STIS imaging modes / filters used by the auroral scientific community to brightness, precipitated power and radiated power in the ultraviolet (700- 1800 Å). Since hydrocarbon absorption may considerably affect the observed auroral emission, the conversion factors are determined for several attenuation levels. Several properties of the auroral emission have been determined: the fraction of the H2 emission shortward and longward of the HLy-a line is 50.3 % and 49.7 % respectively, the contribution of HLy-a to the total unabsorbed auroral signal has been set to 9.1 % and an input of 1 mW m-2 produces 10 kR of H2 in the Lyman and Werner bands. A first application sets the order of magnitude of Saturn's auroral characteristics in the total UV bandwidth to a brightness of 10 kR and an emitted power of ~2.8 GW. A second application uses published brighnesses of Europa's footprint to determine the current density associated with the Europa auroral spot: 0.21 and 0.045 μA m-2 assuming no hydrocarbon absorption and a color ratio of 2, respectively.

  1. Variation reduction of brightness and pH of pulp sent to a paper mill

    Directory of Open Access Journals (Sweden)

    Napassavong Rojanarowan

    2015-03-01

    Full Text Available The variance of the brightness of pulp sent to the paper mill during the changing period of dry pulp grades affects the chemical control in the paper mill. This research aims to determine the mixing formula of pulp with different brightness from the EOP and D1 stages to handle this variation issue. This research uses response surface design with Central Composite Design type, regression technique and optimization technique to find the optimal setting of the mixing formula for each of the seven brightness levels to obtain the target brightness of 86% and the pH of 5.25. The mixing formulas are determined by the pulp mixing percentage and the sulfuric acid consumption. The experimental results reveal that when using higher EOP mixing ratio, the brightness decreases and the pH increases. Regarding the effect of the sulfuric acid, increasing the sulfuric acid makes the brightness and the pH decrease. After implementing the optimal formula in the production line, the mean of pulp brightness is closer to the target compared with the brightness before improvement and the brightness variation decreases without affecting the quality of other pulp grades, average of brightness decreased from 87.4% to 86.3% and standard deviation of brightness decreased from 1.09 to 0.46.

  2. Flux and brightness calculations for various synchrotron radiation sources

    International Nuclear Information System (INIS)

    Weber, J.M.; Hulbert, S.L.

    1991-11-01

    Synchrotron radiation (SR) storage rings are powerful scientific and technological tools. The first generation of storage rings in the US., e.g., SURF (Washington, D.C.), Tantalus (Wisconsin), SSRL (Stanford), and CHESS (Cornell), revolutionized VUV, soft X-ray, and hard X-ray science. The second (present) generation of storage rings, e.g. the NSLS VUV and XRAY rings and Aladdin (Wisconsin), have sustained the revolution by providing higher stored currents and up to a factor of ten smaller electron beam sizes than the first generation sources. This has made possible a large number of experiments that could not performed using first generation sources. In addition, the NSLS XRAY ring design optimizes the performance of wigglers (high field periodic magnetic insertion devices). The third generation storage rings, e.g. ALS (Berkeley) and APS (Argonne), are being designed to optimize the performance of undulators (low field periodic magnetic insertion devices). These extremely high brightness sources will further revolutionize x-ray science by providing diffraction-limited x-ray beams. The output of undulators and wigglers is distinct from that of bending magnets in magnitude, spectral shape, and in spatial and angular size. Using published equations, we have developed computer programs to calculate the flux, central intensity, and brightness output bending magnets and selected wigglers and undulators of the NSLS VUV and XRAY rings, the Advanced Light Source (ALS), and the Advanced Photon Source (APS). Following is a summary of the equations used, the graphs and data produced, and the computer codes written. These codes, written in the C programming language, can be used to calculate the flux, central intensity, and brightness curves for bending magnets and insertion devices on any storage ring

  3. Low surface brightness galaxies in the Fornax Cluster: automated galaxy surface photometry

    International Nuclear Information System (INIS)

    Davies, J.I.; Phillipps, S.; Disney, M.J.

    1988-01-01

    A sample is presented of low surface brightness galaxies (with extrapolated central surface brightness fainter than 22.0 Bμ) in the Fornax Cluster region which has been measured by the APM machine. Photometric parameters, namely profile shape, scale length, central brightness and total magnitude, are derived for the sample galaxies and correlations between the parameters of low surface brightness dwarf galaxies are discussed, with particular reference to the selection limits. Contrary to previous authors we find no evidence for a luminosity-surface brightness correlation in the sense of lower surface brightness galaxies having lower luminosities and scale sizes. In fact, the present data suggest that it is the galaxies with the largest scale lengths which are more likely to be of very low surface brightness. In addition, the larger scale length galaxies occur preferentially towards the centre of the Cluster. (author)

  4. Bright, dark and singular optical solitons in a cascaded system

    International Nuclear Information System (INIS)

    Zhou, Qin; Zhu, Qiuping; Yu, Hua; Liu, Yaxian; Wei, Chun; Yao, Ping; Bhrawy, Ali H; Biswas, Anjan

    2015-01-01

    This work studies nonlinear dynamics of optical solitons in a cascaded system with Kerr law nonlinearity and spatio-temporal dispersion. The mathematical model that describes the propagation of optical solitons through a cascaded system is given by the vector-coupled nonlinear Schrödinger equation. It is investigated analytically using three integration algorithms. The Jacobian elliptic equation expansion method, Bernoulli equation expansion approach and Riccati equation expansion scheme are the integration tools of this model that are recruited to extract singular, bright and dark solitons. The restrictions that need to hold for the existence of these solitons are derived. (paper)

  5. The bright optical afterglow of the long GRB 001007

    DEFF Research Database (Denmark)

    Ceron, J.M.C.; Castro-Tirado, A.J.; Gorosabel, J.

    2002-01-01

    We present optical follow up observations of the long GRB 001007 between 6.14 hours and similar to468 days after the event. An unusually bright optical afterglow (OA) was seen to decline following a steep power law decay with index alpha = -2.03 +/- 0.11, possibly indicating a break in the light...... curve at t - t(0) hours after the gamma ray event provide tentative (1.2σ) evidence for a break in the optical light curve. The spectral index β of the OA yields -1.24 +/- 0.57. These values may be explained both...

  6. Bright X-ray transient in the LMC

    Science.gov (United States)

    Saxton, R.; Read, A. M.; Li, D. Y.

    2018-01-01

    We report a bright X-ray transient in the LMC from an XMM-Newton slew made on 5th January 2018. The source, XMMSL2 J053629.4-675940, had a soft X-ray (0.2-2 keV) count rate in the EPIC-pn detector, medium filter of 1.82+/-0.56 c/s, equivalent to a flux Fx=2.3+/-0.7E-12 ergs/s/cm2 for a nominal spectrum of a power-law of slope 2 absorbed by a column NH=3E20 cm^-2.

  7. Technological Challenges for High-Brightness Photo-Injectors

    CERN Multimedia

    Suberlucq, Guy

    2004-01-01

    Many applications, from linear colliders to free-electron lasers, passing through light sources and many other electron sources, require high brightness electron beams, usually produced by photo-injectors. Because certain parameters of these applications differ by several orders of magnitude, various solutions were implemented for the design and construction of the three main parts of the photo-injectors: lasers, photocathodes and guns. This paper summarizes the different requirements, how they lead to technological challenges and how R&D programs try to overcome these challenges. Some examples of state-of-the-art parts are presented.

  8. Bright photoactivatable fluorophores for single-molecule imaging.

    Science.gov (United States)

    Grimm, Jonathan B; English, Brian P; Choi, Heejun; Muthusamy, Anand K; Mehl, Brian P; Dong, Peng; Brown, Timothy A; Lippincott-Schwartz, Jennifer; Liu, Zhe; Lionnet, Timothée; Lavis, Luke D

    2016-12-01

    Small-molecule fluorophores are important tools for advanced imaging experiments. We previously reported a general method to improve small, cell-permeable fluorophores which resulted in the azetidine-containing 'Janelia Fluor' (JF) dyes. Here, we refine and extend the utility of these dyes by synthesizing photoactivatable derivatives that are compatible with live-cell labeling strategies. Once activated, these derived compounds retain the superior brightness and photostability of the JF dyes, enabling improved single-particle tracking and facile localization microscopy experiments.

  9. Completion of the brightness upgrade of the ALS

    International Nuclear Information System (INIS)

    Steier, C; Madur, A; Bailey, B; Berg, K; Biocca, A; Black, A; Casey, P; Colomb, D; Gunion, B; Li, N; Marks, S; Nishimura, H; Pappas, C; Petermann, K; Portmann, G; Prestemon, S; Rawlins, A; Robin, D; Rossi, S; Scarvie, T

    2014-01-01

    The Advanced Light Source (ALS) at Berkeley Lab remains one of the brightest sources for soft x-rays worldwide. A multiyear upgrade of the ALS is underway, which includes new and replacement x-ray beamlines, a replacement of many of the original insertion devices and many upgrades to the accelerator. The accelerator upgrade that affects the ALS performance most directly is the ALS brightness upgrade [1], which reduces the horizontal emittance from 6.3 to 2.0 nm (2.5 nm effective). Magnets for this upgrade were installed in late 2012 and early 2013 followed by user operation with the reduced emittance.

  10. Generation of high brightness ion beam from insulated anode PED

    International Nuclear Information System (INIS)

    Matsukawa, Yoshinobu

    1988-01-01

    Generation and focusing of a high density ion beam with high brightness from a organic center part of anode of a PED was reported previously. Mass, charge and energy distribution of this beam were analyzed. Three kind of anode were tried. Many highly ionized medium mass ions (up to C 4+ , O 6+ ) accelarated to several times of voltage difference between anode and cathode were observed. In the case of all insulator anode the current carried by the medium mass ions is about half of that carried by protons. (author)

  11. FACT — LONGTERM MONITORING OF BRIGHT TeV BLAZARS

    Directory of Open Access Journals (Sweden)

    Katja Meier

    2014-06-01

    Full Text Available The First G-APD Cherenkov Telescope (FACT, located on the Canary Island of La Palma, has been taking data since October 2011. FACT has been optimized for longterm monitoring of bright TeV blazars, to study their variability time scales and flare probability. G-APD photo-sensors allow for observations even under strong moonlight conditions, and the telescope can be operated remotely. The monitoring strategy of FACT is discussed and preliminary results of the flare of Mrk501 in June 2012 are shown.

  12. Automatic brightness control algorithms and their effect on fluoroscopic imaging

    International Nuclear Information System (INIS)

    Quinn, P.W.; Gagne, R.M.

    1989-01-01

    This paper reports a computer model used to investigate the effect on dose and image quality of three automatic brightness control (ABC) algorithms used in the imaging of barium during general-purpose fluoroscopy. A model incorporating all aspects of image formation - i.e., x- ray production, phantom attenuation, and energy absorption in the CSI phosphor - was driven according to each ABC algorithm as a function of patient thickness. The energy absorbed in the phosphor was kept constant, while the changes in exposure, integral dose, organ dose, and contrast were monitored

  13. Retrieval of an ice water path over the ocean from ISMAR and MARSS millimeter and submillimeter brightness temperatures

    Directory of Open Access Journals (Sweden)

    M. Brath

    2018-02-01

    Full Text Available A neural-network-based retrieval method to determine the snow ice water path (SIWP, liquid water path (LWP, and integrated water vapor (IWV from millimeter and submillimeter brightness temperatures, measured by using airborne radiometers (ISMAR and MARSS, is presented. The neural networks were trained by using atmospheric profiles from the ICON numerical weather prediction (NWP model and by radiative transfer simulations using the Atmospheric Radiative Transfer Simulator (ARTS. The basic performance of the retrieval method was analyzed in terms of offset (bias and the median fractional error (MFE, and the benefit of using submillimeter channels was studied in comparison to pure microwave retrievals. The retrieval is offset-free for SIWP  > 0.01 kg m−2, LWP  > 0.1 kg m−2, and IWV  > 3 kg m−2. The MFE of SIWP decreases from 100 % at SIWP  =  0.01 kg m−2 to 20 % at SIWP  =  1 kg m−2 and the MFE of LWP from 100 % at LWP  = 0.05 kg m−2 to 30 % at LWP  =  1 kg m−2. The MFE of IWV for IWV  > 3 kg m−2 is 5 to 8 %. The SIWP retrieval strongly benefits from submillimeter channels, which reduce the MFE by a factor of 2, compared to pure microwave retrievals. The IWV and the LWP retrievals also benefit from submillimeter channels, albeit to a lesser degree. The retrieval was applied to ISMAR and MARSS brightness temperatures from FAAM flight B897 on 18 March 2015 of a precipitating frontal system west of the coast of Iceland. Considering the given uncertainties, the retrieval is in reasonable agreement with the SIWP, LWP, and IWV values simulated by the ICON NWP model for that flight. A comparison of the retrieved IWV with IWV from 12 dropsonde measurements shows an offset of 0.5 kg m−2 and an RMS difference of 0.8 kg m−2, showing that the retrieval of IWV is highly effective even under cloudy conditions.

  14. EDITORIAL: Extreme Ultraviolet Light Sources for Semiconductor Manufacturing

    Science.gov (United States)

    Attwood, David

    2004-12-01

    filaments, for both Xe and Sn. The embodiment of electrical discharge plasmas and laser-produced plasmas into commercially available EUV sources, with EUV powers that project to suitable levels, is presented in the fifth paper by Uwe Stamm of XTREME Technologies in Göttingen. For discharge produced plasmas, thermal loading and electrode erosion are significant issues. Vladimir Borisov and his colleagues, at the Troitsk Institute outside Moscow, address these issues and provide novel ideas for the multiplexing of several discharge plasmas feeding a single optical system. Igor Fomenkov and his colleagues at Cymer in San Diego describe issues associated with a dense plasma focus pinch, including a comparison of operations with both positive and negative polarity. In the eighth paper, Malcolm McGeoch of Plex in Massachusetts provides a theoretical description of the vaporization and ionization of spherical tin droplets in discharge plasma. Together this cluster of papers provides a broad review of the current status of high power EUV plasma sources for semiconductor manufacturing. This very current topic, of intense interest worldwide, is considered further in a book [4] of collected papers to become available in mid-2005. Additionally, a special journal issue emphasizing coherent EUV sources, albeit at lower average powers, is soon to appear [5]. References [1] http://public.itrsr.net [2] Attwood D 2000 Soft X-Rays and Extreme Ultraviolet Radiation: Principles and Applications (Cambridge: Cambridge University Press) www.coe.Berkeley.edu/AST/sxreuv [3] Moore G E 1965 Cramming More Components onto Integrated Circuits Electronics Magazine 114 Moore G E 1995 Lithography and the Future of Moore's Law SPIE 243 2 [4] Bakshi V ed 2005 EUV Sources for Lithography (Bellingham WA:SPIE) at press [5] IEEE J. Special Topics in Quantum Electronics, Short Wavelength and EUV Lasers 10 Dec 2004 at press

  15. The role of the second zero-dispersion wavelength in generation of supercontinua and bright-bright soliton-pairs across the zero-dispersion wavelength: erratum

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch; Falk, Peter Andreas; Bang, Ole

    2007-01-01

    An erratum is presented explaining that the observation in the original paper (Optics Express, volume 13, issue 16, page 6181-6192, 2005), of a bright-bright soliton with one color in the anomalous dispersion region and the other color in the normal dispersion region was mistaken; both parts...

  16. Disinfection Effect of Film Cassettes by Ultraviolet Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kweon, Dae Cheol; Park, Peom [Ajou Univ., Suwon (Korea, Republic of)

    2001-12-15

    A bacteria infection on film cassette contact surface was examined at the diagnostic radiology department. Studies have demonstrated a bactericidal effect of ultraviolet irradiation, and to assess the contamination level on film cassette contact surface as a predictor of patient prevent from nosocomial infection. The study showed that the laboratory result was identified non-pathologic and pathologic bacterial in the five different cassette size of the contact surface. Film cassettes were exposed to ultraviolet light for 1, 2 and 3 minutes. Ultraviolet light disinfection practices suitable for bacteria. The study concludes that presence of a bacterial infection will prevent a using antiseptic technique on film cassette contact surface. In conclusion, ultraviolet irradiate on film cassette over the surface more than 2 minutes. Ultraviolet dose of 1565 {mu}W {center_dot} s/cm{sup 2}Win in 30 second relative to ultraviolet dose in time.

  17. Disinfection Effect of Film Cassettes by Ultraviolet Irradiation

    International Nuclear Information System (INIS)

    Kweon, Dae Cheol; Park, Peom

    2001-01-01

    A bacteria infection on film cassette contact surface was examined at the diagnostic radiology department. Studies have demonstrated a bactericidal effect of ultraviolet irradiation, and to assess the contamination level on film cassette contact surface as a predictor of patient prevent from nosocomial infection. The study showed that the laboratory result was identified non-pathologic and pathologic bacterial in the five different cassette size of the contact surface. Film cassettes were exposed to ultraviolet light for 1, 2 and 3 minutes. Ultraviolet light disinfection practices suitable for bacteria. The study concludes that presence of a bacterial infection will prevent a using antiseptic technique on film cassette contact surface. In conclusion, ultraviolet irradiate on film cassette over the surface more than 2 minutes. Ultraviolet dose of 1565 μW · s/cm 2 Win in 30 second relative to ultraviolet dose in time

  18. Observations of Bright Massive Stars Using Small Size Telescopes

    Science.gov (United States)

    Beradze, Sopia; Kochiashvili, Nino

    2017-11-01

    The size of a telescope determines goals and objects of observations. During the latest decades it becomes more and more difficult to get photometric data of bright stars because most of telescopes of small sizes do not operate already. But there are rather interesting questions connected to the properties and evolution ties between different types of massive stars. Multi-wavelength photometric data are needed for solution of some of them. We are presenting our observational plans of bright Massive X-ray binaries, WR and LBV stars using a small size telescope. All these stars, which are presented in the poster are observational targets of Sopia Beradze's future PhD thesis. We already have got very interesting results on the reddening and possible future eruption of the massive hypergiant star P Cygni. Therefore, we decided to choose some additional interesting massive stars of different type for future observations. All Massive stars play an important role in the chemical evolution of galaxies because of they have very high mass loss - up to 10-4M⊙/a year. Our targets are on different evolutionary stages and three of them are the members of massive binaries. We plan to do UBVRI photometric observations of these stars using the 48 cm Cassegrain telescope of the Abastumani Astrophisical Observatory.

  19. Bright PanSTARRS Nuclear Transients – what are they?

    Directory of Open Access Journals (Sweden)

    Smartt S.

    2012-12-01

    Full Text Available We present an initial analysis of 49 bright transients occurring in the nuclei of galaxies with no previous known Active Galactic Nucleus (AGN. They have been discovered as part of the PanSTARRs 3π survey, and followed up with the Liverpool Telescope. Based on colours, light curve shape, and a small number with optical spectra, these transients seem to fall into three groups. Red/fast transients are nuclear supernovae of various types. Some bright nuclear transients are blue and decay on a timescale of a few months; these may be candidates for tidal disruption events. However most of the events we have found are blue and are either still rising or decaying slowly, on a timescale of years; the few spectra we have show AGN at z ∼ 1. We argue that these transients are background AGN microlensed by stars in foreground galaxies by a factor 10–100. Monitoring such events gives us very promising prospects for measuring the structure of AGN and so testing current theories.

  20. Bright Solitons in a PT-Symmetric Chain of Dimers

    Directory of Open Access Journals (Sweden)

    Omar B. Kirikchi

    2016-01-01

    Full Text Available We study the existence and stability of fundamental bright discrete solitons in a parity-time- (PT- symmetric coupler composed by a chain of dimers that is modelled by linearly coupled discrete nonlinear Schrödinger equations with gain and loss terms. We use a perturbation theory for small coupling between the lattices to perform the analysis, which is then confirmed by numerical calculations. Such analysis is based on the concept of the so-called anticontinuum limit approach. We consider the fundamental onsite and intersite bright solitons. Each solution has symmetric and antisymmetric configurations between the arms. The stability of the solutions is then determined by solving the corresponding eigenvalue problem. We obtain that both symmetric and antisymmetric onsite mode can be stable for small coupling, in contrast to the reported continuum limit where the antisymmetric solutions are always unstable. The instability is either due to the internal modes crossing the origin or the appearance of a quartet of complex eigenvalues. In general, the gain-loss term can be considered parasitic as it reduces the stability region of the onsite solitons. Additionally, we analyse the dynamic behaviour of the onsite and intersite solitons when unstable, where typically it is either in the form of travelling solitons or soliton blow-ups.

  1. Bright light treatment of depression for older adults [ISRCTN55452501

    Directory of Open Access Journals (Sweden)

    Knickerbocker Nancy C

    2005-11-01

    Full Text Available Abstract Background The incidence of insomnia and depression in the elder population is significant. It is hoped that use of light treatment for this group could provide safe, economic, and effective rapid recovery. Methods In this home-based trial we treated depressed elderly subjects with bright white (8,500 Lux and dim red ( Results Eighty-one volunteers, between 60 and 79 years old, completed the study. Both treatment and placebo groups experienced mood improvement. Average GDS scores improved 5 points, the Hamilton Depression Rating Scale (HDRS 17 scores (extracted from the self-rated SIGH-SAD-SR improved 6 points. There were no significant treatment effects or time-by-treatment interactions. No significant adverse reactions were observed in either treatment group. The assays of urine and saliva showed no significant differences between the treatment and placebo groups. The healthy control group was active earlier and slept earlier but received less light than the depressed group at baseline. Conclusion Antidepressant response to bright light treatment in this age group was not statistically superior to placebo. Both treatment and placebo groups experienced a clinically significant overall improvement of 16%.

  2. Suzaku observations of low surface brightness cluster Abell 1631

    Science.gov (United States)

    Babazaki, Yasunori; Mitsuishi, Ikuyuki; Ota, Naomi; Sasaki, Shin; Böhringer, Hans; Chon, Gayoung; Pratt, Gabriel W.; Matsumoto, Hironori

    2018-06-01

    We present analysis results for a nearby galaxy cluster Abell 1631 at z = 0.046 using the X-ray observatory Suzaku. This cluster is categorized as a low X-ray surface brightness cluster. To study the dynamical state of the cluster, we conduct four-pointed Suzaku observations and investigate physical properties of the Mpc-scale hot gas associated with the A 1631 cluster for the first time. Unlike relaxed clusters, the X-ray image shows no strong peak at the center and an irregular morphology. We perform spectral analysis and investigate the radial profiles of the gas temperature, density, and entropy out to approximately 1.5 Mpc in the east, north, west, and south directions by combining with the XMM-Newton data archive. The measured gas density in the central region is relatively low (a few ×10-4 cm-3) at the given temperature (˜2.9 keV) compared with X-ray-selected clusters. The entropy profile and value within the central region (r clusters. These features are also observed in another low surface brightness cluster, Abell 76. The spatial distributions of galaxies and the hot gas appear to be different. The X-ray luminosity is relatively lower than that expected from the velocity dispersion. A post-merger scenario may explain the observed results.

  3. Inhibition of seagrass photosynthesis by ultraviolet-B radiation.

    Science.gov (United States)

    Trocine, R P; Rice, J D; Wells, G N

    1981-07-01

    Effects of ultraviolet-B radiation on the photosynthesis of seagrasses (Halophila engelmanni Aschers, Halodule wrightii Aschers, and Syringodium filiforme Kütz) were examined. The intrinsic tolerance of each seagrass to ultraviolet-B, the presence and effectiveness of photorepair mechanisms to ultraviolet-B-induced photosynthetic inhibition, and the role of epiphytic growth as a shield from ultraviolet-B were investigated.Halodule was found to possess the greatest photosynthetic tolerance for ultraviolet-B. Photosynthesis in Syringodium was slightly more sensitive to ultraviolet-B while Halophila showed relatively little photosynthetic tolerance. Evidence for a photorepair mechanism was found only in Halodule. This mechanism effectively attenuated photosynthetic inhibition induced by ultraviolet-B dose rates and dosages in excess of natural conditions. Syringodium appeared to rely primarily on a thick epidermal cell layer to reduce photosynthetic damage. Halophila seemed to have no morphological or photorepair capabilities to deal with ultraviolet-B. This species appeared to rely on epiphytic and detrital shielding and the shade provided by other seagrasses to reduce ultraviolet-B irradiation to tolerable levels. The presence of epiphytes on leaf surfaces was found to reduce the extent of photosynthetic inhibition from ultraviolet-B exposure in all species.Observations obtained in this study seem to suggest the possibility of anthocyanin and/or other flavonoid synthesis as an adaptation to long term ultraviolet-B irradiation by these species. In addition, Halophila appears to obtain an increased photosynthetic tolerance to ultraviolet-B as an indirect benefit of chloroplast clumping to avoid photo-oxidation by intense levels of photosynthetically active radiation.

  4. BRITE-Constellation: Nanosatellites for precision photometry of bright stars

    Science.gov (United States)

    Weiss, W. W.; Moffat, A. F. J.; Schwarzenberg-Czerny, A.; Koudelka, O. F.; Grant, C. C.; Zee, R. E.; Kuschnig, R.; Mochnacki, St.; Rucinski, S. M.; Matthews, J. M.; Orleański, P.; Pamyatnykh, A. A.; Pigulski, A.; Alves, J.; Guedel, M.; Handler, G.; Wade, G. A.; Scholtz, A. L.; Scholtz

    2014-02-01

    BRITE-Constellation (where BRITE stands for BRIght Target Explorer) is an international nanosatellite mission to monitor photometrically, in two colours, brightness and temperature variations of stars brighter than V ~ 4, with precision and time coverage not possible from the ground. The current mission design consists of three pairs of 7 kg nanosats (hence ``Constellation'') from Austria, Canada and Poland carrying optical telescopes (3 cm aperture) and CCDs. One instrument in each pair is equipped with a blue filter; the other, a red filter. The first two nanosats (funded by Austria) are UniBRITE, designed and built by UTIAS-SFL (University of Toronto Institute for Aerospace Studies-Space Flight Laboratory) and its twin, BRITE-Austria, built by the Technical University Graz (TUG) with support of UTIAS-SFL. They were launched on 25 February 2013 by the Indian Space Agency, under contract to the Canadian Space Agency. Each BRITE instrument has a wide field of view (~ 24 degrees), so up to 15 bright stars can be observed simultaneously in 32 × 32 sub-rasters. Photometry (with reduced precision but thorough time sampling) of additional fainter targets will be possible through on-board data processing. A critical technical element of the BRITE mission is the three-axis attitude control system to stabilize a nanosat with very low inertia. The pointing stability is better than 1.5 arcminutes rms, a significant advance by UTIAS-SFL over any previous nanosatellite. BRITE-Constellation will primarily measure p- and g-mode pulsations to probe the interiors and ages of stars through asteroseismology. The BRITE sample of many of the brightest stars in the night sky is dominated by the most intrinsically luminous stars: massive stars seen at all evolutionary stages, and evolved medium-mass stars at the very end of their nuclear burning phases (cool giants and AGB stars). The Hertzsprung-Russell diagram for stars brighter than mag V=4 from which the BRITE-Constellation sample

  5. Ultraviolet spectrophotometer for measuring columnar atmospheric ozone from aircraft

    Science.gov (United States)

    Hanser, F. A.; Sellers, B.; Briehl, D. C.

    1978-01-01

    An ultraviolet spectrophotometer (UVS) to measure downward solar fluxes from an aircraft or other high altitude platform is described. The UVS uses an ultraviolet diffuser to obtain large angular response with no aiming requirement, a twelve-position filter wheel with narrow (2-nm) and broad (20-nm) bandpass filters, and an ultraviolet photodiode. The columnar atmospheric ozone above the UVS (aircraft) is calculated from the ratios of the measured ultraviolet fluxes. Comparison with some Dobson station measurements gives agreement to 2%. Some UVS measured ozone profiles over the Pacific Ocean for November 1976 are shown to illustrate the instrument's performance.

  6. In-orbit Calibrations of the Ultraviolet Imaging Telescope

    Science.gov (United States)

    Tandon, S. N.; Subramaniam, Annapurni; Girish, V.; Postma, J.; Sankarasubramanian, K.; Sriram, S.; Stalin, C. S.; Mondal, C.; Sahu, S.; Joseph, P.; Hutchings, J.; Ghosh, S. K.; Barve, I. V.; George, K.; Kamath, P. U.; Kathiravan, S.; Kumar, A.; Lancelot, J. P.; Leahy, D.; Mahesh, P. K.; Mohan, R.; Nagabhushana, S.; Pati, A. K.; Kameswara Rao, N.; Sreedhar, Y. H.; Sreekumar, P.

    2017-09-01

    The Ultra-Violet Imaging Telescope (UVIT) is one of the payloads in ASTROSAT, the first Indian Space Observatory. The UVIT instrument has two 375 mm telescopes: one for the far-ultraviolet (FUV) channel (1300-1800 Å), and the other for the near-ultraviolet (NUV) channel (2000-3000 Å) and the visible (VIS) channel (3200-5500 Å). UVIT is primarily designed for simultaneous imaging in the two ultraviolet channels with spatial resolution better than 1.″8, along with provisions for slit-less spectroscopy in the NUV and FUV channels. The results of in-orbit calibrations of UVIT are presented in this paper.

  7. In-orbit Calibrations of the Ultraviolet Imaging Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Tandon, S. N. [Inter-University Center for Astronomy and Astrophysics, Pune (India); Subramaniam, Annapurni; Sankarasubramanian, K.; Sriram, S.; Stalin, C. S.; Mondal, C.; Sahu, S.; Joseph, P.; Barve, I. V.; George, K.; Kamath, P. U.; Kathiravan, S.; Kumar, A.; Lancelot, J. P.; Mahesh, P. K. [Indian Institute of Astrophysics, Koramangala II Block, Bangalore-560034 (India); Girish, V. [ISRO Satellite Centre, HAL Airport Road, Bangalore 560017 (India); Postma, J.; Leahy, D. [University of Calgary, 2500 University Drive NW, Calgary, Alberta Canada (Canada); Hutchings, J. [National Research Council of Canada, Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Ghosh, S. K., E-mail: purni@iiap.res.in [National Centre for Radio Astrophysics, Pune (India); and others

    2017-09-01

    The Ultra-Violet Imaging Telescope (UVIT) is one of the payloads in ASTROSAT, the first Indian Space Observatory. The UVIT instrument has two 375 mm telescopes: one for the far-ultraviolet (FUV) channel (1300–1800 Å), and the other for the near-ultraviolet (NUV) channel (2000–3000 Å) and the visible (VIS) channel (3200–5500 Å). UVIT is primarily designed for simultaneous imaging in the two ultraviolet channels with spatial resolution better than 1.″8, along with provisions for slit-less spectroscopy in the NUV and FUV channels. The results of in-orbit calibrations of UVIT are presented in this paper.

  8. Micro Coronal Bright Points Observed in the Quiet Magnetic Network by SOHO/EIT

    Science.gov (United States)

    Falconer, D. A.; Moore, R. L.; Porter, J. G.

    1997-01-01

    When one looks at SOHO/EIT Fe XII images of quiet regions, one can see the conventional coronal bright points (> 10 arcsec in diameter), but one will also notice many smaller faint enhancements in brightness (Figure 1). Do these micro coronal bright points belong to the same family as the conventional bright points? To investigate this question we compared SOHO/EIT Fe XII images with Kitt Peak magnetograms to determine whether the micro bright points are in the magnetic network and mark magnetic bipoles within the network. To identify the coronal bright points, we applied a picture frame filter to the Fe XII images; this brings out the Fe XII network and bright points (Figure 2) and allows us to study the bright points down to the resolution limit of the SOHO/EIT instrument. This picture frame filter is a square smoothing function (hlargelyalf a network cell wide) with a central square (quarter of a network cell wide) removed so that a bright point's intensity does not effect its own background. This smoothing function is applied to the full disk image. Then we divide the original image by the smoothed image to obtain our filtered image. A bright point is defined as any contiguous set of pixels (including diagonally) which have enhancements of 30% or more above the background; a micro bright point is any bright point 16 pixels or smaller in size. We then analyzed the bright points that were fully within quiet regions (0.6 x 0.6 solar radius) centered on disk center on six different days.

  9. Ultraviolet air disinfection for protection against influenza

    International Nuclear Information System (INIS)

    Riley, R.L.

    1977-01-01

    Three converging lines of evidence support the belief that it may be possible, under appropriate circumstances, to interrupt the airborne transmission of influenza by ultraviolet (UV) air disinfection. These lines of evidence are: (a) that influenza is airborne; (b) that UV irradiation of the upper air of a room can provide safe and effective disinfection of air in the lower part of the room; and (c) that epidemic spread of airborne viral infections in humans can be prevented if the population under consideration remains in the UV-protected environment

  10. Far ultraviolet spectrophotometry of BD +28 4211

    Science.gov (United States)

    Cook, Timothy A.; Cash, Webster; Green, James C.

    1991-01-01

    The results are reported of a November 1989 rocket flight which recorded a flux-calibrated spectrum of BD +28 4211 from 912 to 1150 A with 1A resolution. BD +28 4211, an SdO-type star, is commonly used as an ultraviolet calibration source in the IUE wavelength band. The present work extends the useful range of this standard shortward of Lyman-alpha. Since previous experiments show marked disparity, this study can be useful in determining a standard in the 912 to 1216 A band.

  11. Probing nanoscale ferroelectricity by ultraviolet Raman spectroscopy.

    Science.gov (United States)

    Tenne, D A; Bruchhausen, A; Lanzillotti-Kimura, N D; Fainstein, A; Katiyar, R S; Cantarero, A; Soukiassian, A; Vaithyanathan, V; Haeni, J H; Tian, W; Schlom, D G; Choi, K J; Kim, D M; Eom, C B; Sun, H P; Pan, X Q; Li, Y L; Chen, L Q; Jia, Q X; Nakhmanson, S M; Rabe, K M; Xi, X X

    2006-09-15

    We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature (Tc) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are not only ferroelectric (with Tc as high as 250 kelvin) but also polarize the quantum paraelectric SrTiO3 layers adjacent to them. Tc was tuned by approximately 500 kelvin by varying the thicknesses of the BaTiO3 and SrTiO3 layers, revealing the essential roles of electrical and mechanical boundary conditions for nanoscale ferroelectricity.

  12. Ultraviolet Flux Variation of Epsilon Aurigae

    Directory of Open Access Journals (Sweden)

    Young Woon Kang

    1990-06-01

    Full Text Available The eighteen ultraviolet light curves of Epsilon Aurigae have been plotted using the integrated fluxes reduced from the 233 IUE low dispersion spectra taken between 1978 and 1986. The times of contacts and depth of eclipse have been determined from the light curves at the wavelength from 2550 Å to 3050 Å. The UV light curves show two brightenings during the totality, the downward slope of the variation from the second to the third contacts, and asymmetry of the eclipse light curve. The two selected spectra note that the energy density distribution is not changed between the totality of the eclipse and out-of-eclipse.

  13. Dynamical structure of extreme ultraviolet macrospicules

    Science.gov (United States)

    Karovska, Margarita; Habbal, Shadia Rifai

    1994-01-01

    We describe the substructures forming the macrospicules and their temporal evolution, as revealed by the application of an image enhancement algorithm to extreme ultraviolet (EUV) observations of macrospicules. The enhanced images uncover, for the first time, the substructures forming the column-like structures within the macrospicules and the low-lying arches at their base. The spatial and temporal evolution of macrospicules clearly show continuous interaction between these substructures with occasional ejection of plasma following a ballistic trajectory. We comment on the importance of these results for planning near future space observations of macrospicules with better temporal and spatial resolution.

  14. Impact of Ultraviolet Light on Vitiligo.

    Science.gov (United States)

    Singh, Rasnik K

    2017-01-01

    Vitiligo is a disorder of the melanocytes that results in a dynamic spectrum of skin depigmentation. Its etiology is complex and multifactorial, with data supporting several different hypotheses. Given its prominent phenotype, vitiligo has a significant negative impact on quality of life. Coupled with the chronic and incurable nature of the disease, this presents a formidable treatment challenge. Several treatment modalities have been instituted over the years, with varying efficacy. This chapter focuses on the use of ultraviolet light in vitiligo as an established therapeutic option.

  15. FAINT NEAR-ULTRAVIOLET/FAR-ULTRAVIOLET STANDARDS FROM SWIFT/UVOT, GALEX, AND SDSS PHOTOMETRY

    International Nuclear Information System (INIS)

    Siegel, Michael H.; Hoversten, Erik A.; Roming, Peter W. A.; Brown, Peter

    2010-01-01

    At present, the precision of deep ultraviolet photometry is somewhat limited by the dearth of faint ultraviolet standard stars. In an effort to improve this situation, we present a uniform catalog of 11 new faint (u ∼ 17) ultraviolet standard stars. High-precision photometry of these stars has been taken from the Sloan Digital Sky Survey and Galaxy Evolution Explorer archives and combined with new data from the Swift Ultraviolet Optical Telescope to provide precise photometric measures extending from the near-infrared to the far-ultraviolet. These stars were chosen because they are known to be hot (20, 000 eff < 50, 000 K) DA white dwarfs with published Sloan spectra that should be photometrically stable. This careful selection allows us to compare the combined photometry and Sloan spectroscopy to models of pure hydrogen atmospheres to both constrain the underlying properties of the white dwarfs and test the ability of white dwarf models to predict the photometric measures. We find that the photometry provides good constraints on white dwarf temperatures, which demonstrates the ability of Swift/UVOT to investigate the properties of hot luminous stars. We further find that the models reproduce the photometric measures in all 11 passbands to within their systematic uncertainties. Within the limits of our photometry, we find the standard stars to be photometrically stable. This success indicates that the models can be used to calibrate additional filters to our standard system, permitting easier comparison of photometry from heterogeneous sources. The largest source of uncertainty in the model fitting is the uncertainty in the foreground reddening curve, a problem that is especially acute in the UV.

  16. Effect of evening exposure to bright or dim light after daytime bright light on absorption of dietary carbohydrates the following morning.

    Science.gov (United States)

    Hirota, Naoko; Sone, Yoshiaki; Tokura, Hiromi

    2010-01-01

    We had previously reported on the effect of exposure to light on the human digestive system: daytime bright light exposure has a positive effect, whereas, evening bright light exposure has a negative effect on the efficiency of dietary carbohydrate absorption from the evening meal. These results prompted us to examine whether the light intensity to which subjects are exposed in the evening affects the efficiency of dietary carbohydrate absorption the following morning. In this study, subjects were exposed to either 50 lux (dim light conditions) or 2,000 lux (bright light conditions) in the evening for 9 h (from 15:00 to 24:00) after staying under bright light in the daytime (under 2,000 lux from 07:00 to 15:00). We measured unabsorbed dietary carbohydrates using the breath-hydrogen test the morning after exposure to either bright light or dim light the previous evening. Results showed that there was no significant difference between the two conditions in the amount of breath hydrogen. This indicates that evening exposure to bright or dim light after bright light exposure in the daytime has no varying effect on digestion or absorption of dietary carbohydrates in the following morning's breakfast.

  17. Ultraviolet and Infrared Correlation Studies in Orion

    Directory of Open Access Journals (Sweden)

    Bose Lakshmi S.

    2015-09-01

    Full Text Available We have studied the variation of diffuse ultraviolet (UV radiation in the northern part of the Orion constellation using a set of eight areas of the GALEX All-Sky Imaging Survey in the far and near UV. Different components of diffuse UV radiation, like dust scattered emission and H2 fluorescence, were quantified and separated after removing the point sources and the foreground emission in each of the fields. Then the dependence of the individual UV components on the infrared 100 μm dust emission was studied. We did not find any positive correlation between the diffuse-UV and IR-100 micron intensities, probably due to the high optical depth of the region or the entire dust column not contributing to the diffuse UV radiation. However, in the far UV we noticed the presence of an excess emission in addition to the dust scattered radiation, which is clearly absent in the near UV. This excess emission, identified as the H2 fluorescence, is produced by the Trapezium stars in the surrounding molecular clouds. We also compare our results with those of previous studies in the region, based on Far Ultraviolet Spectroscopic Explorer (FUSE observations.

  18. ULTRAVIOLET EXTINCTION AT HIGH GALACTIC LATITUDES

    Energy Technology Data Exchange (ETDEWEB)

    Peek, J. E. G.; Schiminovich, David, E-mail: jegpeek@gmail.com [Department of Astronomy, Columbia University, New York, NY (United States)

    2013-07-01

    In order to study the properties and effects of high Galactic latitude dust, we present an analysis of 373,303 galaxies selected from the Galaxy Evolution Explorer All-Sky Survey and Wide-field Infrared Explorer All-Sky Data Release. By examining the variation in aggregate ultraviolet colors and number density of these galaxies, we measure the extinction curve at high latitude. We additionally consider a population of spectroscopically selected galaxies from the Sloan Digital Sky Survey to measure extinction in the optical. We find that dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws. Extinction in the FUV and NUV is {approx}10% and {approx}35% higher than expected, with significant variation across the sky. We find that no single R{sub V} parameter fits both the optical and ultraviolet extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related. We propose that the overall trends we detect likely stem from an increase in very small silicate grains in the interstellar medium.

  19. ULTRAVIOLET EXTINCTION AT HIGH GALACTIC LATITUDES

    International Nuclear Information System (INIS)

    Peek, J. E. G.; Schiminovich, David

    2013-01-01

    In order to study the properties and effects of high Galactic latitude dust, we present an analysis of 373,303 galaxies selected from the Galaxy Evolution Explorer All-Sky Survey and Wide-field Infrared Explorer All-Sky Data Release. By examining the variation in aggregate ultraviolet colors and number density of these galaxies, we measure the extinction curve at high latitude. We additionally consider a population of spectroscopically selected galaxies from the Sloan Digital Sky Survey to measure extinction in the optical. We find that dust at high latitude is neither quantitatively nor qualitatively consistent with standard reddening laws. Extinction in the FUV and NUV is ∼10% and ∼35% higher than expected, with significant variation across the sky. We find that no single R V parameter fits both the optical and ultraviolet extinction at high latitude, and that while both show detectable variation across the sky, these variations are not related. We propose that the overall trends we detect likely stem from an increase in very small silicate grains in the interstellar medium.

  20. Inhibition of DNA replication by ultraviolet light

    International Nuclear Information System (INIS)

    Edenberg, H.J.

    1976-01-01

    DNA replication in ultraviolet-irradiated HeLa cells was studied by two different techniques: measurements of the kinetics of semiconservative DNA synthesis, and DNA fiber autoradiography. In examining the kinetics of semiconservative DNA synthesis, density label was used to avoid measuring the incorporation due to repair replication. The extent of inhibition varied with time. After doses of less than 10 J/m 2 the rate was initially depressed but later showed some recovery. After higher doses, a constant, low rate of synthesis was seen for at least the initial 6 h. An analysis of these data indicated that the inhibition of DNA synthesis could be explained by replication forks halting at pyrimidine dimers. DNA fiber autoradiography was used to further characterize replication after ultraviolet irradiation. The average length of labeled segments in irradiated cells increased in the time immediately after irradiation, and then leveled off. This is the predicted pattern if DNA synthesis in each replicon continued at its previous rate until a lesion is reached, and then halted. The frequency of lesions that block synthesis is approximately the same as the frequency of pyrimidine dimers

  1. Photomorphogenic responses to ultraviolet-B light.

    Science.gov (United States)

    Jenkins, Gareth I

    2017-11-01

    Exposure to ultraviolet B (UV-B) light regulates numerous aspects of plant metabolism, morphology and physiology through the differential expression of hundreds of genes. Photomorphogenic responses to UV-B are mediated by the photoreceptor UV RESISTANCE LOCUS8 (UVR8). Considerable progress has been made in understanding UVR8 action: the structural basis of photoreceptor function, how interaction with CONSTITUTIVELY PHOTOMORPHOGENIC 1 initiates signaling and how REPRESSOR OF UV-B PHOTOMORPHOGENESIS proteins negatively regulate UVR8 action. In addition, recent research shows that UVR8 mediates several responses through interaction with other signaling pathways, in particular auxin signaling. Nevertheless, many aspects of UVR8 action remain poorly understood. Most research to date has been undertaken with Arabidopsis, and it is important to explore the functions and regulation of UVR8 in diverse plant species. Furthermore, it is essential to understand how UVR8, and UV-B signaling in general, regulates processes under natural growth conditions. Ultraviolet B regulates the expression of many genes through UVR8-independent pathways, but the activity and importance of these pathways in plants growing in sunlight are poorly understood. © 2017 John Wiley & Sons Ltd.

  2. STELLAR ACTIVITY IN THE BROADBAND ULTRAVIOLET

    International Nuclear Information System (INIS)

    Findeisen, K.; Hillenbrand, L.; Soderblom, D.

    2011-01-01

    The completion of the GALEX All-Sky Survey in the ultraviolet allows activity measurements to be acquired for many more stars than is possible with the limited sensitivity of ROSAT or the limited sky coverage of Chandra, XMM, or spectroscopic surveys for line emission in the optical or ultraviolet. We have explored the use of GALEX photometry as an activity indicator, using stars within 50 pc as a calibration sample representing the field and in selected nearby associations representing the youngest stages of stellar evolution. We present preliminary relations between UV flux and the optical activity indicator R' HK and between UV flux and age. We demonstrate that far-UV (FUV, 1350-1780 A) excess flux is roughly proportional to R' HK . We also detect a correlation between near-UV (NUV, 1780-2830 A) flux and activity or age, but the effect is much more subtle, particularly for stars older than ∼0.5-1 Gyr. Both the FUV and NUV relations show large scatter, ∼0.2 mag when predicting UV flux, ∼0.18 dex when predicting R' HK , and ∼0.4 dex when predicting age. This scatter appears to be evenly split between observational errors in current state-of-the-art data and long-term activity variability in the sample stars.

  3. Large-area and bright pulsed electroluminescence in monolayer semiconductors

    KAUST Repository

    Lien, Der-Hsien; Amani, Matin; Desai, Sujay B.; Ahn, Geun Ho; Han, Kevin; He, Jr-Hau; Ager, Joel W.; Wu, Ming C.; Javey, Ali

    2018-01-01

    Transition-metal dichalcogenide monolayers have naturally terminated surfaces and can exhibit a near-unity photoluminescence quantum yield in the presence of suitable defect passivation. To date, steady-state monolayer light-emitting devices suffer from Schottky contacts or require complex heterostructures. We demonstrate a transient-mode electroluminescent device based on transition-metal dichalcogenide monolayers (MoS, WS, MoSe, and WSe) to overcome these problems. Electroluminescence from this dopant-free two-terminal device is obtained by applying an AC voltage between the gate and the semiconductor. Notably, the electroluminescence intensity is weakly dependent on the Schottky barrier height or polarity of the contact. We fabricate a monolayer seven-segment display and achieve the first transparent and bright millimeter-scale light-emitting monolayer semiconductor device.

  4. Hacking commercial quantum cryptography systems by tailored bright illumination

    Science.gov (United States)

    Lydersen, Lars; Wiechers, Carlos; Wittmann, Christoffer; Elser, Dominique; Skaar, Johannes; Makarov, Vadim

    2010-10-01

    The peculiar properties of quantum mechanics allow two remote parties to communicate a private, secret key, which is protected from eavesdropping by the laws of physics. So-called quantum key distribution (QKD) implementations always rely on detectors to measure the relevant quantum property of single photons. Here we demonstrate experimentally that the detectors in two commercially available QKD systems can be fully remote-controlled using specially tailored bright illumination. This makes it possible to tracelessly acquire the full secret key; we propose an eavesdropping apparatus built from off-the-shelf components. The loophole is likely to be present in most QKD systems using avalanche photodiodes to detect single photons. We believe that our findings are crucial for strengthening the security of practical QKD, by identifying and patching technological deficiencies.

  5. Relationships between brightness of nighttime lights and population density

    Science.gov (United States)

    Naizhuo, Z.

    2012-12-01

    Brightness of nighttime lights has been proven to be a good proxy for socioeconomic and demographic statistics. Moreover, the satellite nighttime lights data have been used to spatially disaggregate amounts of gross domestic product (GDP), fossil fuel carbon dioxide emission, and electric power consumption (Ghosh et al., 2010; Oda and Maksyutov, 2011; Zhao et al., 2012). Spatial disaggregations were performed in these previous studies based on assumed linear relationships between digital number (DN) value of pixels in the nighttime light images and socioeconomic data. However, reliability of the linear relationships was never tested due to lack of relative high-spatial-resolution (equal to or finer than 1 km × 1 km) statistical data. With the similar assumption that brightness linearly correlates to population, Bharti et al. (2011) used nighttime light data as a proxy for population density and then developed a model about seasonal fluctuations of measles in West Africa. The Oak Ridge National Laboratory used sub-national census population data and high spatial resolution remotely-sensed-images to produce LandScan population raster datasets. The LandScan population datasets have 1 km × 1 km spatial resolution which is consistent with the spatial resolution of the nighttime light images. Therefore, in this study I selected 2008 LandScan population data as baseline reference data and the contiguous United State as study area. Relationships between DN value of pixels in the 2008 Defense Meteorological Satellite Program's Operational Linescan System (DMSP-OLS) stable light image and population density were established. Results showed that an exponential function can more accurately reflect the relationship between luminosity and population density than a linear function. Additionally, a certain number of saturated pixels with DN value of 63 exist in urban core areas. If directly using the exponential function to estimate the population density for the whole brightly

  6. Design of ultrahigh brightness solar-pumped disk laser.

    Science.gov (United States)

    Liang, Dawei; Almeida, Joana

    2012-09-10

    To significantly improve the solar-pumped laser beam brightness, a multi-Fresnel lens scheme is proposed for side-pumping either a single-crystal Nd:YAG or a core-doped ceramic Sm(3+) Nd:YAG disk. Optimum laser system parameters are found through ZEMAX and LASCAD numerical analysis. An ultrahigh laser beam figure of merit B of 53 W is numerically calculated, corresponding to a significant enhancement of more than 180 times over the previous record. 17.7 W/m(2) collection efficiency is also numerically attained. The strong thermal effects that have hampered present-day rod-type solar-pumped lasers can also be largely alleviated.

  7. PG 1553 + 11 - A bright optically selected BL Lacertae object

    International Nuclear Information System (INIS)

    Falomo, R.; Treves, A.

    1990-01-01

    A detailed study of the bright optically selected BL Lac object PG 1553 + 11 is presented. UV observations, obtained during a high state of the source, together with simultaneous optical spectrophotometry and near-IR photometry, allow the spectral flux distribution to be examined from 8 x 10 to the 13th to 2.5 x 10 to the 15th Hz. This distribution is compared with that derived from quasi-simultaneous observations obtained when the source was a factor of about 3 fainter. It is found that, in the higher state, the spectrum can be described by two power laws connected by a break at about 10 to the 15th Hz, while in the low state the shape is more complex. The overall spectrum of the object is compared with the average energy distribution of X-ray and radio-selected BL Lac objects, showing that it is closer to the former class. 25 refs

  8. Beyond the Kepler/K2 bright limit

    DEFF Research Database (Denmark)

    White, T. R.; Pope, B. J. S.; Antoci, V.

    2017-01-01

    The most powerful tests of stellar models come from the brightest stars in the sky, for which complementary techniques, such as astrometry, asteroseismology, spectroscopy and interferometry, can be combined. The K2 mission is providing a unique opportunity to obtain high-precision photometric time...... have developed a new photometric technique, which we call halo photometry, to observe very bright stars using a limited number of pixels. Halo photometry is simple, fast and does not require extensive pixel allocation, and will allow us to use K2 and other photometric missions, such as TESS, to observe...... to 2000 ppm. For the star Maia, we demonstrate the utility of combining K2 photometry with spectroscopy and interferometry to show that it is not a 'Maia variable', and to establish that its variability is caused by rotational modulation of a large chemical spot on a 10 d time-scale....

  9. ROLE OF DIAMOND SECONDARY EMITTERS IN HIGH BRIGHTNESS ELECTRON SOURCES

    International Nuclear Information System (INIS)

    2005-01-01

    In this paper we explore the possibility of using diamond secondary emitter in a high average current electron injector to amplify the current from the photocathode and to isolate the cathode and the injector from each other to increase the life time of the cathode and preserve the performance of the injector. Secondary electron yield of 225 and current density of 0.8 a/cm 2 have been measured in the transmission mode from type 2 a natural diamond. Although the diamond will be heated during normal operation in the injector, calculations indicate that by cryogenically cooling the diamond, the temperature gradient along the diamond can be maintained within the acceptable range. The electron energy and temporal distributions are expected to be narrow from this device resulting in high brightness beams. Plans are underway to measure the SEY in emission mode, fabricate photocathode-diamond capsule and test diamond and capsule in superconducting RF injector

  10. A new, bright and hard aluminum surface produced by anodization

    Science.gov (United States)

    Hou, Fengyan; Hu, Bo; Tay, See Leng; Wang, Yuxin; Xiong, Chao; Gao, Wei

    2017-07-01

    Anodized aluminum (Al) and Al alloys have a wide range of applications. However, certain anodized finishings have relatively low hardness, dull appearance and/or poor corrosion resistance, which limited their applications. In this research, Al was first electropolished in a phosphoric acid-based solution, then anodized in a sulfuric acid-based solution under controlled processing parameters. The anodized specimen was then sealed by two-step sealing method. A systematic study including microstructure, surface morphology, hardness and corrosion resistance of these anodized films has been conducted. Results show that the hardness of this new anodized film was increased by a factor of 10 compared with the pure Al metal. Salt spray corrosion testing also demonstrated the greatly improved corrosion resistance. Unlike the traditional hard anodized Al which presents a dull-colored surface, this newly developed anodized Al alloy possesses a very bright and shiny surface with good hardness and corrosion resistance.

  11. High-brightness electron source driven by laser

    International Nuclear Information System (INIS)

    Zhao Kui; Geng Rongli; Wang Lifang

    1996-01-01

    A DC high-brightness laser driven by photo emissive electron gun is being developed at Beijing University, in order to produce 50∼100 ps electron bunches of high quality. The gun consists of a photocathode preparation chamber and a DC acceleration cavity. Different ways of fabricating photocathode, such as chemical vapor deposition, ion beam implantation and ion beam enhanced deposition, can be adopted. The acceleration gap is designed with the aid of simulation codes EGUN and POISSON. 100 kV DC high voltage is fed to the anode through a careful designed ceramic insulator. The laser system is a mode locked Nd-YAG oscillator proceeded by an amplifier at 10 Hz repetition rate, which can deliver three different wavelength (1064/532/266 nm). The combination of a superconducting cavity with the photocathode preparation chamber is discussed

  12. Efficiency of observer brightness discrimination in original and subracted images

    International Nuclear Information System (INIS)

    Swensson, R.G.; Kazda, I.; Nawfel, R.; Judy, P.F.

    1990-01-01

    This paper reports that, for an optimal image calculation, discriminating pairs of objects that differ only in brightness is equivalent to discriminating polarity differences in their subtraction images. This experiment measured and compared how efficiently human observers could perform the two different discriminations posed by such original and subtracted images. Disks of equal size, separated by their diameter, were superimposed on incorrelated, Gaussian noise backgrounds at different contrasts that made the two disks readily visible on the displayed radiographs. The digitally subtracted image-regions containing the two disks of each pair (shifted to registration) produced subtraction images with low-contrast disks that were either brighter or darker than the background. Observer performances in each task (measured by receiver operating characteristic [ROC] analysis) was compared with that of an optimal calculation (cross- correlator)

  13. Criteria for emittance compensation in high-brightness photoinjectors

    Directory of Open Access Journals (Sweden)

    Chun-xi Wang

    2007-10-01

    Full Text Available A critical process in high-brightness photoinjectors is emittance compensation, which brings under control the correlated transverse emittance growth due to the linear space-charge force. Although emittance compensation has been used and studied for almost two decades, the exact criteria to achieve emittance compensation is not as clear as it should be. In this paper, a perturbative analysis of slice envelopes and emittance evolution close to any reference envelope is developed, via which space-charge and chromatic effects are investigated. A new criterion for emittance compensation is found, which is complementary to the well-known matching condition for the invariant envelope and agrees very well with simulations.

  14. High Brightness Injectors Based On Photocathode DC Gun

    International Nuclear Information System (INIS)

    B. Yunn

    2001-01-01

    Sample results of new injector design method based on a photocathode dc gun are presented, based on other work analytically proving the validity of the emittance compensation scheme for the case even when beam bunching is involved. We have designed several new injectors appropriate for different bunch charge ranges accordingly. Excellent beam quality produced by these injectors clearly shows that a photocathode dc gun can compete with a rf gun on an equal footing as the source of an electron beam for the bunch charge ranging up to 2 nano Coulomb (nC). This work therefore elevates a dc gun based injector to the preferred choice for many ongoing high brightness accelerator projects considering the proven operational stability and high average power capability of the dc gun

  15. Beam position monitors for the high brightness lattice

    International Nuclear Information System (INIS)

    Ring, T.

    1985-06-01

    Engineering developments associated with the high brightness lattice and the projected change in machine operating parameters will inherently affect the diagnostics systems and devices installed at present in the storage ring. This is particularly true of the beam position monitoring (BPI) system. The new sixteen unit cell lattice with its higher betatron tune values and the limited space available in the redesigned machine straights for fitting standard BPI vessels forces a fundamental re-evaluation of the beam position monitor system. The design aims for the new system are based on accepting the space limitations imposed while still providing the monitor points required to give good radial and vertical closed orbit plots. The locations of BPI's in the redesigned machine straights is illustrated. A description of the new BPI assemblies and their calibration is given. The BPI's use capacitance button type pick-ups; their response is described. (U.K.)

  16. Multiwavelength Coverage of a Bright Flare from Sgr A

    International Nuclear Information System (INIS)

    Trap, G.; Goldwurm, A.; Terrier, R.

    2009-01-01

    The dynamical center of our galaxy hosts a supermassive black hole, Sgr A*, which has been the target of an extensive multiwavelength campaign for a week in April 2007. We report here the detection of a bright flare from the vicinity of the horizon, observed simultaneously in X-rays (XMM-Newton) and NIR (VLT/NACO) on April 4 th . For the first time, such an event also benefitted from a soft γ-rays (INTEGRAL/ISGRI) and MIR (VLT/VISIR) coverage, which enabled us to derive upper limits at both ends of Sgr A* spectral energy distribution (SED). We discuss the physical implications of the contemporaneous light curves as well as the SED, in terms of synchrotron, synchrotron self-Compton and external Compton emission processes.

  17. Discovery of a bright quasar without a massive host galaxy.

    Science.gov (United States)

    Magain, Pierre; Letawe, Géraldine; Courbin, Frédéric; Jablonka, Pascale; Jahnke, Knud; Meylan, Georges; Wisotzki, Lutz

    2005-09-15

    A quasar is thought to be powered by the infall of matter onto a supermassive black hole at the centre of a massive galaxy. Because the optical luminosity of quasars exceeds that of their host galaxy, disentangling the two components can be difficult. This led in the 1990s to the controversial claim of the discovery of 'naked' quasars. Since then, the connection between quasars and galaxies has been well established. Here we report the discovery of a quasar lying at the edge of a gas cloud, whose size is comparable to that of a small galaxy, but whose spectrum shows no evidence for stars. The gas in the cloud is excited by the quasar itself. If a host galaxy is present, it is at least six times fainter than would normally be expected for such a bright quasar. The quasar is interacting dynamically with a neighbouring galaxy, whose gas might be feeding the black hole.

  18. Investigation of fundamental limits to beam brightness available from photoinjectors

    International Nuclear Information System (INIS)

    Bazarov, Ivan

    2015-01-01

    The goal of this project was investigation of fundamental limits to beam brightness available from photoinjectors. This basic research in accelerator physics spanned over 5 years aiming to extend the fundamental understanding of high average current, low emittance sources of relativistic electrons based on photoemission guns, a necessary prerequisite for a new generation of coherent X-ray synchrotron radiation facilities based on continuous duty superconducting linacs. The program focused on two areas critical to making advances in the electron source performance: 1) the physics of photocathodes for the production of low emittance electrons and 2) control of space charge forces in the immediate vicinity to the cathode via 3D laser pulse shaping.

  19. Large-area and bright pulsed electroluminescence in monolayer semiconductors

    KAUST Repository

    Lien, Der-Hsien

    2018-04-04

    Transition-metal dichalcogenide monolayers have naturally terminated surfaces and can exhibit a near-unity photoluminescence quantum yield in the presence of suitable defect passivation. To date, steady-state monolayer light-emitting devices suffer from Schottky contacts or require complex heterostructures. We demonstrate a transient-mode electroluminescent device based on transition-metal dichalcogenide monolayers (MoS, WS, MoSe, and WSe) to overcome these problems. Electroluminescence from this dopant-free two-terminal device is obtained by applying an AC voltage between the gate and the semiconductor. Notably, the electroluminescence intensity is weakly dependent on the Schottky barrier height or polarity of the contact. We fabricate a monolayer seven-segment display and achieve the first transparent and bright millimeter-scale light-emitting monolayer semiconductor device.

  20. Investigation of fundamental limits to beam brightness available from photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    Bazarov, Ivan [Cornell Univ., Ithaca, NY (United States)

    2015-07-09

    The goal of this project was investigation of fundamental limits to beam brightness available from photoinjectors. This basic research in accelerator physics spanned over 5 years aiming to extend the fundamental understanding of high average current, low emittance sources of relativistic electrons based on photoemission guns, a necessary prerequisite for a new generation of coherent X-ray synchrotron radiation facilities based on continuous duty superconducting linacs. The program focused on two areas critical to making advances in the electron source performance: 1) the physics of photocathodes for the production of low emittance electrons and 2) control of space charge forces in the immediate vicinity to the cathode via 3D laser pulse shaping.

  1. Three Millisecond Pulsars in Fermi LAT Unassociated Bright Sources

    Science.gov (United States)

    Ransom, S. M.; Ray, P. S.; Camilo, F.; Roberts, M. S. E.; Celik, O.; Wolff, M. T.; Cheung, C. C.; Kerr, M.; Pennucci, T.; DeCesar, M. E.; hide

    2010-01-01

    We searched for radio pulsars in 25 of the non-variable, unassociated sources in the Fermi LAT Bright Source List with the Green Bank Telescope at 820 MHz. We report the discovery of three radio and gamma-ray millisecond pulsar (MSPs) from a high Galactic latitude subset of these sources. All of the pulsars are in binary systems, which would have made them virtually impossible to detect in blind gamma-ray pulsation searches. They seem to be relatively normal, nearby (pulsars are power law in nature with exponential cutoffs at a few Ge V, as has been found with most other pulsars. The MSPs have all been detected as X-ray point sources. Their soft X-ray luminosities of approx 10(exp 30) - 10(exp 31) erg/s are typical of the rare radio MSPs seen in X-rays.

  2. IRAS bright galaxy sample. II. The sample and luminosity function

    International Nuclear Information System (INIS)

    Soifer, B.T.; Sanders, D.B.; Neugebauer, G.; Madore, B.F.; Danielson, G.E.; David Dunlap Observatory, Richmond Hill, Canada; Palomar Observatory; California Institute of Technology, Pasadena)

    1987-01-01

    A statistically complete sample of 324 of the brightest infrared galaxies discovered at 60 microns in the IRAS all-sky survey is described. The results show that far-infrared emission is a significant luminosity component in the local universe, representing 25 percent of the luminosity emitted by stars in the same volume. Above 10 to the 11th solar luminosities, the infrared luminous galaxies are the dominant population of objects in the universe, being as numerous as the Seyfert galaxies and more numerous than quasars at higher luminosities. The infrared luminosity appears to be independent of the optical luminosity of galaxies. Most infrared bright galaxies appear to require much of the interstellar matter to be contributing to the observed infrared luminosity. Approximately 60-80 percent of the far-infrared luminosity of the local universe can be attributed, directly or indirectly, to recent or ongoing star formation. 67 references

  3. Multiwavelength Study of Gamma-Ray Bright Blazars

    Science.gov (United States)

    Morozova, Daria; Larionov, V. M.; Hagen-Thorn, V. A.; Jorstad, S. G.; Marscher, A. P.; Troitskii, I. S.

    2011-01-01

    We investigate total intensity radio images of 6 gamma-ray bright blazars (BL Lac, 3C 279, 3C 273, W Com, PKS 1510-089, and 3C 66A) and their optical and gamma-ray light curves to study connections between gamma-ray and optical brightness variations and changes in the parsec-scale radio structure. We use high-resolution maps obtained by the BU group at 43 GHz with the VLBA, optical light curves constructed by the St.Petersburg State U. (Russia) team using measurements with the 0.4 m telescope of St.Petersburg State U. (LX200) and the 0.7 m telescope of the Crimean Astrophysical Observatory (AZT-8), and gamma-ray light curves, which we have constructed with data provided by the Fermi Large Area Telescope. Over the period from August 2008 to November 2009, superluminal motion is found in all 6 objects with apparent speed ranging from 2c to 40c. The blazars with faster apparent speeds, 3C 273, 3C 279, PKS 1510-089, and 3C 66A, exhibit stronger variability of the gamma-ray emission. There is a tendency for sources with sharply peaked gamma-ray flares to have faster jet speed than sources with gamma-ray light curves with no sharp peaks. Gamma-ray light curves with sharply peaked gamma-ray flares possess a stronger gamma-ray/optical correlations. The research at St.Petersburg State U. was funded by the Minister of Education and Science of the Russian Federation (state contract N#P123). The research at BU was funded in part by NASA Fermi Guest Investigator grant NNX08AV65G and by NSF grant AST-0907893. The VLBA is an instrument of the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  4. Suzaku observations of low surface brightness cluster Abell 1631

    Science.gov (United States)

    Babazaki, Yasunori; Mitsuishi, Ikuyuki; Ota, Naomi; Sasaki, Shin; Böhringer, Hans; Chon, Gayoung; Pratt, Gabriel W.; Matsumoto, Hironori

    2018-04-01

    We present analysis results for a nearby galaxy cluster Abell 1631 at z = 0.046 using the X-ray observatory Suzaku. This cluster is categorized as a low X-ray surface brightness cluster. To study the dynamical state of the cluster, we conduct four-pointed Suzaku observations and investigate physical properties of the Mpc-scale hot gas associated with the A 1631 cluster for the first time. Unlike relaxed clusters, the X-ray image shows no strong peak at the center and an irregular morphology. We perform spectral analysis and investigate the radial profiles of the gas temperature, density, and entropy out to approximately 1.5 Mpc in the east, north, west, and south directions by combining with the XMM-Newton data archive. The measured gas density in the central region is relatively low (a few ×10-4 cm-3) at the given temperature (˜2.9 keV) compared with X-ray-selected clusters. The entropy profile and value within the central region (r < 0.1 r200) are found to be flatter and higher (≳400 keV cm2). The observed bolometric luminosity is approximately three times lower than that expected from the luminosity-temperature relation in previous studies of relaxed clusters. These features are also observed in another low surface brightness cluster, Abell 76. The spatial distributions of galaxies and the hot gas appear to be different. The X-ray luminosity is relatively lower than that expected from the velocity dispersion. A post-merger scenario may explain the observed results.

  5. Human responses to bright light of different durations.

    Science.gov (United States)

    Chang, Anne-Marie; Santhi, Nayantara; St Hilaire, Melissa; Gronfier, Claude; Bradstreet, Dayna S; Duffy, Jeanne F; Lockley, Steven W; Kronauer, Richard E; Czeisler, Charles A

    2012-07-01

    Light exposure in the early night induces phase delays of the circadian rhythm in melatonin in humans. Previous studies have investigated the effect of timing, intensity, wavelength, history and pattern of light stimuli on the human circadian timing system. We present results from a study of the duration–response relationship to phase-delaying bright light. Thirty-nine young healthy participants (16 female; 22.18±3.62 years) completed a 9-day inpatient study. Following three baseline days, participants underwent an initial circadian phase assessment procedure in dim light (light pulse (∼10,000 lux) of 0.2 h, 1.0 h, 2.5 h or 4.0 h duration during a 4.5 h controlled-posture episode centred in a 16 h wake episode. After another 8 h sleep episode, participants completed a second circadian phase assessment. Phase shifts were calculated from the difference in the clock time of the dim light melatonin onset (DLMO) between the initial and final phase assessments. Exposure to varying durations of bright light reset the circadian pacemaker in a dose-dependent, non-linear manner. Per minute of exposure, the 0.2 h duration was over 5 times more effective at phase delaying the circadian pacemaker (1.07±0.36 h) as compared with the 4.0 h duration (2.65±0.24 h). Acute melatonin suppression and subjective sleepiness also had a dose-dependent response to light exposure duration. These results provide strong evidence for a non-linear resetting response of the human circadian pacemaker to light duration.

  6. State-Of High Brightness RF Photo-Injector Design

    Science.gov (United States)

    Ferrario, Massimo; Clendenin, Jym; Palmer, Dennis; Rosenzweig, James; Serafini, Luca

    2000-04-01

    The art of designing optimized high brightness electron RF Photo-Injectors has moved in the last decade from a cut and try procedure, guided by experimental experience and time consuming particle tracking simulations, up to a fast parameter space scanning, guided by recent analytical results and a fast running semi-analytical code, so to reach the optimum operating point which corresponds to maximum beam brightness. Scaling laws and the theory of invariant envelope provide to the designers excellent tools for a first parameters choice and the code HOMDYN, based on a multi-slice envelope description of the beam dynamics, is tailored to describe the space charge dominated dynamics of laminar beams in presence of time dependent space charge forces, giving rise to a very fast modeling capability for photo-injectors design. We report in this talk the results of a recent beam dynamics study, motivated by the need to redesign the LCLS photoinjector. During this work a new effective working point for a split RF photoinjector has been discovered by means of the previous mentioned approach. By a proper choice of rf gun and solenoid parameters, the emittance evolution shows a double minimum behavior in the drifting region. If the booster is located where the relative emittance maximum and the envelope waist occur, the second emittance minimum can be shifted at the booster exit and frozen at a very low level (0.3 mm-mrad for a 1 nC flat top bunch), to the extent that the invariant envelope matching conditions are satisfied.

  7. Advanced prior modeling for 3D bright field electron tomography

    Science.gov (United States)

    Sreehari, Suhas; Venkatakrishnan, S. V.; Drummy, Lawrence F.; Simmons, Jeffrey P.; Bouman, Charles A.

    2015-03-01

    Many important imaging problems in material science involve reconstruction of images containing repetitive non-local structures. Model-based iterative reconstruction (MBIR) could in principle exploit such redundancies through the selection of a log prior probability term. However, in practice, determining such a log prior term that accounts for the similarity between distant structures in the image is quite challenging. Much progress has been made in the development of denoising algorithms like non-local means and BM3D, and these are known to successfully capture non-local redundancies in images. But the fact that these denoising operations are not explicitly formulated as cost functions makes it unclear as to how to incorporate them in the MBIR framework. In this paper, we formulate a solution to bright field electron tomography by augmenting the existing bright field MBIR method to incorporate any non-local denoising operator as a prior model. We accomplish this using a framework we call plug-and-play priors that decouples the log likelihood and the log prior probability terms in the MBIR cost function. We specifically use 3D non-local means (NLM) as the prior model in the plug-and-play framework, and showcase high quality tomographic reconstructions of a simulated aluminum spheres dataset, and two real datasets of aluminum spheres and ferritin structures. We observe that streak and smear artifacts are visibly suppressed, and that edges are preserved. Also, we report lower RMSE values compared to the conventional MBIR reconstruction using qGGMRF as the prior model.

  8. Characterizing bars in low surface brightness disc galaxies

    Science.gov (United States)

    Peters, Wesley; Kuzio de Naray, Rachel

    2018-05-01

    In this paper, we use B-band, I-band, and 3.6 μm azimuthal light profiles of four low surface brightness galaxies (LSBs; UGC 628, F568-1, F568-3, F563-V2) to characterize three bar parameters: length, strength, and corotation radius. We employ three techniques to measure the radius of the bars, including a new method using the azimuthal light profiles. We find comparable bar radii between the I-band and 3.6 μm for all four galaxies when using our azimuthal light profile method, and that our bar lengths are comparable to those in high surface brightness galaxies (HSBs). In addition, we find the bar strengths for our galaxies to be smaller than those for HSBs. Finally, we use Fourier transforms of the B-band, I-band, and 3.6 μm images to characterize the bars as either `fast' or `slow' by measuring the corotation radius via phase profiles. When using the B- and I-band phase crossings, we find three of our galaxies have faster than expected relative bar pattern speeds for galaxies expected to be embedded in centrally dense cold dark matter haloes. When using the B-band and 3.6 μm phase crossings, we find more ambiguous results, although the relative bar pattern speeds are still faster than expected. Since we find a very slow bar in F563-V2, we are confident that we are able to differentiate between fast and slow bars. Finally, we find no relation between bar strength and relative bar pattern speed when comparing our LSBs to HSBs.

  9. SURFACE BRIGHTNESS PROFILES OF DWARF GALAXIES. I. PROFILES AND STATISTICS

    International Nuclear Information System (INIS)

    Herrmann, Kimberly A.; Hunter, Deidre A.; Elmegreen, Bruce G.

    2013-01-01

    Radial surface brightness profiles of spiral galaxies are classified into three types: (I) single exponential, or the light falls off with one exponential to a break before falling off (II) more steeply, or (III) less steeply. Profile breaks are also found in dwarf disks, but some dwarf Type IIs are flat or increasing out to a break before falling off. Here we re-examine the stellar disk profiles of 141 dwarfs: 96 dwarf irregulars (dIms), 26 Blue Compact Dwarfs (BCDs), and 19 Magellanic-type spirals (Sms). We fit single, double, or even triple exponential profiles in up to 11 passbands: GALEX FUV and NUV, ground-based UBVJHK and Hα, and Spitzer 3.6 and 4.5 μm. We find that more luminous galaxies have brighter centers, larger inner and outer scale lengths, and breaks at larger radii; dwarf trends with M B extend to spirals. However, the V-band break surface brightness is independent of break type, M B , and Hubble type. Dwarf Type II and III profiles fall off similarly beyond the breaks but have different interiors and IIs break ∼twice as far as IIIs. Outer Type II and III scale lengths may have weak trends with wavelength, but pure Type II inner scale lengths clearly decrease from the FUV to visible bands whereas Type III inner scale lengths increase with redder bands. This suggests the influence of different star formation histories on profile type, but nonetheless the break location is approximately the same in all passbands. Dwarfs continue trends between profile and Hubble types such that later-type galaxies have more Type II but fewer Type I and III profiles than early-type spirals. BCDs and Sms are over-represented as Types III and II, respectively, compared to dIms

  10. Bright solitons in coupled defocusing NLS equation supported by coupling: Application to Bose-Einstein condensation

    International Nuclear Information System (INIS)

    Adhikari, Sadhan K.

    2005-01-01

    We demonstrate the formation of bright solitons in coupled self-defocusing nonlinear Schroedinger (NLS) equation supported by attractive coupling. As an application we use a time-dependent dynamical mean-field model to study the formation of stable bright solitons in two-component repulsive Bose-Einstein condensates (BECs) supported by interspecies attraction in a quasi one-dimensional geometry. When all interactions are repulsive, there cannot be bright solitons. However, bright solitons can be formed in two-component repulsive BECs for a sufficiently attractive interspecies interaction, which induces an attractive effective interaction among bosons of same type

  11. Dark and bright solitons in a quasi-one-dimensional Bose-Einstein condensate

    International Nuclear Information System (INIS)

    Wang, Shun-Jin; Jia, Cheng-Long; An, Jun-Hong; Zhao, Dun; Luo, Hong-Gang

    2003-01-01

    The analytical dark and bright soliton solutions of the one-dimensional Gross-Pitaevskii equation with a confining potential are obtained. For the bright soliton, the recent experimental finding is studied, and the particle number of the soliton and the window of the particle numbers for the bright soliton to occur are estimated analytically and in good agreement with the experimental data. The existence of dark soliton for the attractive interaction and bright soliton for the repulsive interaction is predicted under proper conditions

  12. Bright galaxies in the Fornax cluster. Automated galaxy surface photometry: Pt. 7

    International Nuclear Information System (INIS)

    Disney, M.J.; Phillipps, S.; Davies, J.L.; Cawson, M.G.M.; Kibblewhite, E.J.

    1990-01-01

    We have determined surface-brightness profiles for all galaxies down to magnitude B = 16 in the central region of the Fornax cluster. Using existing redshift data, we have determined the distributions of surface brightness for both the whole sample and for cluster disc galaxies only. Although both distributions peak at extrapolated central surface brightness ∼ 21.7B mag/arcsec 2 (the canonical result), it is shown that they are, in fact, consistent with very broad distributions of disc central surface brightness once selection effects and the effects of bulge contamination of the profile are taken into account. (author)

  13. Observation of near-infrared surface brightness of the large Magellanic cloud

    International Nuclear Information System (INIS)

    Hayakawa, Satio; Koizumi, Yutaka; Matsumoto, Toshio; Murakami, Hiroshi; Uyama, Kiichiro.

    1981-01-01

    The near-infrared surface brightness of the large Magellanic cloud was observed by an infrared telescope carried by a balloon. The balloon flight was made at Australian Balloon Launching Station. The brightness distribution of 2.4 Mu m radiation was obtained. A part of Bar was bright, and the expansion of the contour at the east end of Bar corresponded to the 30 Dor region. Many near-infrared sources distribute in this region. Discussions on the color and brightness of the center of Bar and the 30 Dor region are presented. (Kato, T.)

  14. Pollen and spores as biological recorders of past ultraviolet irradiance

    NARCIS (Netherlands)

    Jardine, P.E.; Fraser, W.T.; Lomax, B.H.; Sephton, M.A.; Shanahan, T.M.; Miller, C.S.; Gosling, W.D.

    2016-01-01

    Solar ultraviolet (UV) irradiance is a key driver of climatic and biotic change. Ultraviolet irradiance modulates stratospheric warming and ozone production, and influences the biosphere from ecosystem-level processes through to the largest scale patterns of diversification and extinction. Yet our

  15. Ultraviolet radiation, human health, and the urban forest

    Science.gov (United States)

    Gordon M. Heisler; Richard H. Grant

    2000-01-01

    Excess exposure to ultraviolet (UV) radiation from the sun, particularly the ultraviolet B (UVB) portion, has been linked with adverse effects on human health ranging from skin cancers to eye diseases such as cataracts. Trees may prevent even greater disease rates in humans by reducing UV exposure. Tree shade greatly reduces UV irradiance when both the sun and sky are...

  16. An assessment of ultraviolet radiation components of light emitted ...

    African Journals Online (AJOL)

    An assessment of ultraviolet radiation components of light emitted from electric arc and their possible exposure risks. ... The study of Ultraviolet Radiation has of recent become interesting because of the health hazards it poses to human. Apart from its intensity reaching the earth from the sun, other man-made sources have ...

  17. 21 CFR 872.6070 - Ultraviolet activator for polymerization.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultraviolet activator for polymerization. 872.6070 Section 872.6070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... ultraviolet radiation intended to polymerize (set) resinous dental pit and fissure sealants or restorative...

  18. 21 CFR 880.6500 - Medical ultraviolet air purifier.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical ultraviolet air purifier. 880.6500 Section 880.6500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... to ultraviolet radiation. (b) Classification. Class II (performance standards). ...

  19. 21 CFR 878.4630 - Ultraviolet lamp for dermatologic disorders.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultraviolet lamp for dermatologic disorders. 878.4630 Section 878.4630 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... disorders is a device (including a fixture) intended to provide ultraviolet radiation of the body to...

  20. Ultraviolet microscopy aids in cytological and biomedical research

    Science.gov (United States)

    Schlenk, F.; Svihla, B.

    1967-01-01

    Ultraviolet microscopy is used by cytologists and biochemists to study the morphological and physiological changes in the living cell under varied culture conditions. The yeast cell is used because of its content of ultraviolet absorbing materials and its lack of motility.

  1. Ultraviolet solar radiation and the prevention of erythema

    International Nuclear Information System (INIS)

    Tena, F.; Martinez-Lozano, J.A.; Utrillas, M.P.

    1998-01-01

    An ultraviolet index appropriate for its use in Spain is studied on the basis of those already available in other countries. The suitability of this index to characterise ultraviolet solar radiation and, particularly, the potential risks to human health are discussed. Finally, the main factors affecting this index are identified and their influence is studied. (Author) 43 refs

  2. Does ultraviolet radiation affect the xanthophyll cycle in marine phytoplankton?

    NARCIS (Netherlands)

    van de Poll, W.H.; Buma, A.G.J.

    2009-01-01

    This Perspective summarizes the state of knowledge of the impact of ultraviolet radiation on the photoprotective xanthophyll cycle in marine phytoplankton. Excess photosynthetically active radiation (PAR; 400-700 nm) and ultraviolet radiation (UVR; 280-400 nm) affect various cellular processes and

  3. Ultraviolet radiation, cancer of the skin and immunology

    International Nuclear Information System (INIS)

    Suurmond, D.

    1984-01-01

    The effects of near and far ultraviolet radiation on the development of skin neoplasms are reviewed. Especially the role of ultraviolet radiation in immunosuppression is discussed as a possible working mechanism of the tumor promoting the effect of this radiation, beside effects on DNA-repair. (Auth.)

  4. Resveratrol anti-ultraviolet-induced guinea pig skin injury

    International Nuclear Information System (INIS)

    Li Wenxing; Zhao Ying

    2014-01-01

    Objective: To Estimate on the protection effect of Stilbene on skin damage induced by ultraviolet radiation. Methods: After the normal skin in guinea pig under the intervene of Resveratrol was irradiated with over- dose of ultraviolet rays (UVB and UVA), the samples in every group were matched and compared. Results: The skin tissue in the Resveratrol intervene group irradiated by ultraviolet rays didn't change obviously as compared with that in the self-control group. But, the damage skin tissue in the control group irradiated by ultraviolet did change significantly as compared with that in the Stilbene intervene group. Conclusion: Resveratrol is a good material to protect the skin from damage effect by ultraviolet radiation. (authors)

  5. FAR-ULTRAVIOLET OBSERVATIONS OF THE SPICA NEBULA AND THE INTERACTION ZONE

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yeon-Ju; Min, Kyoung-Wook; Lim, Tae-Ho; Jo, Young-Soo [Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Seon, Kwang-Il [Korea Astronomy and Space Science Institute (KASI), 61-1 Hwaam-dong, Yuseong-gu, Daejeon 305-348 (Korea, Republic of); Park, Jae-Woo, E-mail: zmzm83@kaist.ac.kr [Korea Intellectual Property Office (KIPO), Government Complex Daejeon Building 4, 189 Cheongsa-ro, Seo-gu, Daejeon 305-348 (Korea, Republic of)

    2013-09-01

    We report the analysis results of far-ultraviolet (FUV) observations, made for a broad region around {alpha} Vir (Spica) including the interaction zone of Loop I and the Local Bubble. The whole region was optically thin and a general correlation was seen between the FUV continuum intensity and the dust extinction, except in the neighborhood of the bright central star, indicating the dust scattering nature of the FUV continuum. We performed Monte Carlo radiative transfer simulations to obtain the optical parameters related to the dust scattering as well as to the geometrical structure of the region. The albedo and asymmetry factor were found to be 0.38 {+-} 0.06 and 0.46 {+-} 0.06, respectively, in good agreement with the Milky Way dust grain models. The distance to and the thickness of the interaction zone were estimated to be 70{sup +4}{sub -8} pc and 40{sup +8}{sub -10} pc, respectively. The diffuse FUV continuum in the northern region above Spica was mostly the result of scattering of the starlight from Spica, while that in the southern region was mainly due to the background stars. The C IV {lambda}{lambda}1548, 1551 emission was found throughout the whole region, in contrast to the Si II* {lambda}1532 emission which was bright only within the H II region. This indicates that the C IV line arises mostly at the shell boundaries of the bubbles, with a larger portion likely from the Loop I than from the Local Bubble side, whereas the Si II* line is from the photoionized Spica Nebula.

  6. A GALEX ULTRAVIOLET IMAGING SURVEY OF GALAXIES IN THE LOCAL VOLUME

    International Nuclear Information System (INIS)

    Lee, Janice C.; Gil de Paz, Armando; Kennicutt, Robert C. Jr; Bothwell, Matthew; Johnson, Benjamin D.; Dalcanton, Julianne; Funes S. J., Jose G.; Sakai, Shoko; Skillman, Evan; Tremonti, Christy; Van Zee, Liese

    2011-01-01

    We present results from a GALEX ultraviolet (UV) survey of a complete sample of 390 galaxies within ∼11 Mpc of the Milky Way. The UV data are a key component of the composite Local Volume Legacy, an ultraviolet-to-infrared imaging program designed to provide an inventory of dust and star formation in nearby spiral and irregular galaxies. The ensemble data set is an especially valuable resource for studying star formation in dwarf galaxies, which comprise over 80% of the sample. We describe the GALEX survey programs that obtained the data and provide a catalog of far-UV (∼1500 A) and near-UV (∼2200 A) integrated photometry. General UV properties of the sample are briefly discussed. We compute two measures of the global star formation efficiency, the star formation rate (SFR) per unit H I gas mass, and the SFR per unit stellar mass, to illustrate the significant differences that can arise in our understanding of dwarf galaxies when the FUV is used to measure the SFR instead of Hα. We find that dwarf galaxies may not be as drastically inefficient in converting gas into stars as suggested by prior Hα studies. In this context, we also examine the UV properties of late-type dwarf galaxies that appear to be devoid of star formation because they were not detected in previous Hα narrowband observations. Nearly all such galaxies in our sample are detected in the FUV and have FUV SFRs that fall below the limit where the Hα flux is robust to Poisson fluctuations in the formation of massive stars. Otherwise, the UV colors and star formation efficiencies of Hα-undetected, UV-bright dwarf irregulars appear to be relatively unremarkable with respect to those exhibited by the general population of star-forming galaxies.

  7. High intensity vacuum ultraviolet and extreme ultraviolet production by noncollinear mixing in laser vaporized media

    Energy Technology Data Exchange (ETDEWEB)

    Todt, Michael A.; Albert, Daniel R.; Davis, H. Floyd, E-mail: hfd1@cornell.edu [Baker Laboratory, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301 (United States)

    2016-06-15

    A method is described for generating intense pulsed vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) laser radiation by resonance enhanced four-wave mixing of commercial pulsed nanosecond lasers in laser vaporized mercury under windowless conditions. By employing noncollinear mixing of the input beams, the need of dispersive elements such as gratings for separating the VUV/XUV from the residual UV and visible beams is eliminated. A number of schemes are described, facilitating access to the 9.9–14.6 eV range. A simple and convenient scheme for generating wavelengths of 125 nm, 112 nm, and 104 nm (10 eV, 11 eV, and 12 eV) using two dye lasers without the need for dye changes is described.

  8. Ultraviolet-visible spectroscopy of graphene oxides

    Directory of Open Access Journals (Sweden)

    Qi Lai

    2012-09-01

    Full Text Available Dispersions of few-layer (1-3 layers, multi-layer (4-10 layers and thick-layer (>10 layers graphene oxide (GO were prepared by a modified Hummers method with different mass ratios of KMnO4 to graphite. Ultraviolet-visible (UV-vis spectroscopic data show that few-layer GO dispersions can be distinguished from multi- and thick-layer dispersions by a more intense peak at 230 nm. Atomic force microscopy (AFM images of few-layer GO contain a single peak, those of multi-layer GO exhibit a shoulder and those of thick-layer GO do not contain a peak or shoulder. These findings allow qualitative analysis of GO dispersions. X-ray photoelectron spectra (XPS show that the change of UV-vis absorption intensity of GO is caused by a conjugative effect related to chromophore aggregation that influences the π-π* plasmon peak.

  9. Preoperative ultraviolet B inflammation in skin

    DEFF Research Database (Denmark)

    Lunn, T H; Dawes, J M; Denk, F

    2018-01-01

    BACKGROUND: Neuroimmune interactions play a vital role in many of the most common pain conditions, such as arthritis. There have been many attempts to derive clinically predictive information from an individual's inflammatory response in order to gauge subsequent pain perception. OBJECTIVES: Here......, we wanted to test whether this effort could be enhanced and complemented by the use of a model system which takes into account the function of not just circulating, but also tissue-resident immune cells: ultraviolet B (UVB) irradiation of the skin. METHODS: We conducted psychophysical...... in the skin might predict the degree of a patient's neuro-immune response and the extent of their postoperative pain after total knee arthroplasty....

  10. Recovery of phage lambda from ultraviolet damage

    International Nuclear Information System (INIS)

    Devoret, R.; Blanco, M.; George, J.; Radman, M.

    1975-01-01

    Recovery of phage lambda from ultraviolet damage can occur, in the dark, through three types of repair processes as defined by microbiological tests: host-cell reactivation, prophage reactivation, and uv reactivation. This paper reviews the properties of the three repair processes, analyzes their dependence on the functioning of bacterial and phage genes, and discusses their relationship. Progress in the understanding of the molecular mechanisms underlying the three repair processes has been relatively slow, particularly for uv reactivation. It has been shown that host-cell reactivation is due to pyrimidine dimer excision and that prophage reactivation is due to genetic recombination (prereplicative). We provide evidence showing that neither of these mechanisms accounts for uv reactivation of phage lambda. Furthermore, uv reactivation differs from the other repair processes in that it is inducible and error-prone. Whether uv-damaged bacterial DNA is subject to a similar repair process is still an open question

  11. Al nanogrid electrode for ultraviolet detectors.

    Science.gov (United States)

    Ding, G; Deng, J; Zhou, L; Gan, Q; Hwang, J C M; Dierolf, V; Bartoli, F J; Mazuir, C; Schoenfeld, W V

    2011-09-15

    Optical properties of Al nanogrids of different pitches and gaps were investigated both theoretically and experimentally. Three-dimensional finite-difference time-domain simulation predicted that surface plasmons at the air/Al interface would enhance ultraviolet transmission through the subwavelength gaps of the nanogrid, making it an effective electrode on GaN-based photodetectors to compensate for the lack of transparent electrode and high p-type doping. The predicted transmission enhancement was verified by confocal scanning optical microscopy performed at 365 nm. The quality of the nanogrids fabricated by electron-beam lithography was verified by near-field scanning optical microscopy and scanning electron microscopy. Based on the results, the pitch and gap of the nanogrids can be optimized for the best trade-off between electrical conductivity and optical transmission at different wavelengths. Based on different cutoff wavelengths, the nanogrids can also double as a filter to render photodetectors solar-blind.

  12. Some resistance mechanisms to ultraviolet radiation

    International Nuclear Information System (INIS)

    Alcantara D, D.

    2002-12-01

    The cyclical exposure of bacterial cells to the ultraviolet light (UV) it has as consequence an increment in the resistance to the lethal effects of this type of radiation, increment that happens as a result of a selection process of favorable genetic mutations induced by the same UV light. With object to study the reproducibility of the genetic changes and the associate mechanisms to the resistance to UV in the bacteria Escherichia coli, was irradiated cyclically with UV light five different derived cultures of a single clone, being obtained five stumps with different resistance grades. The genetic mapping Hfr revealed that so much the mutation events like of selection that took place during the adaptation to the UV irradiation, happened of random manner, that is to say, each one of the resistant stumps it is the result of the unspecified selection of mutations arisen at random in different genes related with the repair and duplication of the DNA. (Author)

  13. Phototherapy cabinet for ultraviolet radiation therapy

    International Nuclear Information System (INIS)

    Horwitz, S.N.; Frost, P.

    1981-01-01

    A newly designed cabinet can be used for the treatment of psoriasis with fluorescent ultraviolet (UV) lamps. the new design provides more uniform distribution of UV radiation in both the horizontal and vertical axes, and several safety features have been added. The distribution and uniformity of UV output in this and in a previously described cabinet are compared. The UV output at the vertical center of the older UV light cabinet was six times greater than that at either the top or bottom, while the design of the present cabinet provides uniform UV radiation except for a slight increase at head height and at the level of the lower legs compared with the middle third of the cabinet. The variation in output of the older cabinet may, in part, explain the commonly encountered difficulty in the phototherapy of psoriasis of the scalp and lower extremities

  14. Ultraviolet-laser ablation of skin

    Energy Technology Data Exchange (ETDEWEB)

    Lane, R.J.; Linsker, R.; Wynne, J.J.; Torres, A.; Geronemus, R.G.

    1985-05-01

    The authors report on the use of pulsed ultraviolet-laser irradiation at 193 nm from an argon-fluoride laser and at 248 nm from a krypton-fluoride laser to ablate skin. In vitro, both wavelengths performed comparably, removing tissue precisely and cleanly, and leaving minimal thermal damage to the surrounding tissue. In vivo, the 193-nm laser radiation failed to remove tissue after bleeding began. The 248-nm radiation, however, continued to remove tissue despite bleeding and left a clean incision with only minimal thermal damage. The krypton-fluoride excimer laser beam at 248 nm, which should be deliverable through a quartz optical fiber, has great potential as a surgical instrument.

  15. Solar maximum ultraviolet spectrometer and polarimeter

    Science.gov (United States)

    Tandberg-Hanssen, E.; Woodgate, B. E.; Brandt, J. C.; Chapman, R. D.; Hyder, C. L.; Michalitsianos, A. G.; Shine, R. A.; Athay, R. G.; Beckers, J. M.; Bruner, E. C.

    1979-01-01

    The objectives of the UVSP experiment are to study solar ultraviolet radiations, particularly from flares and active regions, and to measure constituents in the terrestrial atmosphere by the extinction of sunlight at satellite dawn and dusk. The instrument is designed to observe the Sun at a variety of spectral and spatial resolutions in the range from 1150 to 3600 A. A Gregorian telescope with effective focal length of 1.8 m is used to feed a 1 m Ebert-Fastie spectrometer. A polarimeter containing rotatable magnesium fluoride waveplates is included behind the spectrometer entrance slit and will allow all four Stokes parameters to be determined. Velocities on the Sun can also be measured. The instrument is controlled by a computer which can interact with the data stream to modify the observing program. The observing modes, including rasters, spectral scans, velocity measurements, and polarimetry, are also described along with plans for mission operations, data handling, and analysis of the observations.

  16. Ultraviolet reflectance by the cere of raptors

    Science.gov (United States)

    Mougeot, François; Arroyo, Beatriz E

    2006-01-01

    Ultraviolet (UV) signals have been shown to play key roles in social and sexual signalling in birds. Using a spectrophotometer, we analysed the colour of the cere (skin above the beak) of a diurnal raptor, the Montagu's harrier (Circus pygargus), and show that it reflects in the UV part of the spectrum. The cere is a well-known sexual signal in raptors, with carotenoid based pigmentation being indicative of quality. We thus hypothesized that UV reflectance also signals quality. Accordingly, we found that in our sample of wild males, the location of the UV peak was related to the orangeness of cere and correlated with male body mass and condition (mass corrected for size). Also, males with brighter UV were mated to females that laid earlier, as expected if UV reflectance relates to a male's quality and attractiveness. Future studies should investigate the relationships between UV reflectance and carotenoid pigmentation of cere, and test how UV reflectance influences mate choice. PMID:17148356

  17. Free-electron lasers in ultraviolet photobiology

    International Nuclear Information System (INIS)

    Coohill, T.P.; Sutherland, J.C.

    1989-01-01

    The potential uses for a free-electron laser (FEL), tunable in wavelength from 10 to 400 nm, for photobiological experiments is discussed. Inherent problems of cell and molecular absorption, especially in certain regions of the ultraviolet (UV), are addressed. Absorption values for living cells and viruses at selected wavelengths in the UV are tabulated, and a calculation of the flux needed to inactivate mammalian cells is included. A comparison is made of the UV output of a proposed rf-linac FEL with those of a monochromator, a tunable dye laser, and a synchrotron. The advantages of a UV FEL are apparent, especially in the wavelength regions where the cross section for absorption by biological molecules is low, i.e., 300 to 400 nm and 10 to 200 nm. It is apparent that a UV FEL would be an ideal source for a variety of biological studies that use both intact organisms and isolated cells and viruses

  18. Protection from solar ultraviolet radiation by clothing

    Energy Technology Data Exchange (ETDEWEB)

    Pailthorpe, M. [New South Wales Univ., Kensington, NSW (Australia)

    1996-12-31

    The recently published Australia/New Zealand Standard AS/NZS 4399: l996 `Sun Protective Clothing - Evaluation and Classification` specifies an in vitro spectrophotometric method for the measurement of the ultraviolet (WR) transmission of textiles. Ultraviolet Protection Factors (UPF) are then calculated by convolving the UVR transmission data with standard CIE erythemal response data and ARL solar irradiance data. At the present time the scope of the standard is limited to loose fitting dry clothing. Virtually every textile parameter has an influence on the UPF of the finished garment and hence on the protection afforded to skin from the harmful effects of solar UVR radiation. Textile parameters such as fibre type, the method of spinning the yarn, fabric structure, cover factor, colorant, UVR absorbers and finishing methods determine the UPF of the fabric and hence must be controlled from batch to batch. Since garments generally shrink when washed, multiple wearing and washing cycles usually cause an increase in fabric UPF. Adventitious soiling of fabrics and the absorption of certain components of domestic laundry formulations, e g fluorescent whitening agents, increase fabric UPF ratings. Garments with a high degree of elasticity, e g nylon/lycra sportswear, that are stretched on to fit, will obviously have lower UPFs when stretched than when relaxed. In general fabrics worn in a wet state provide lower protection than when worn dry. On Australia`s most extreme summer day it has been estimated that there are 30 MEDs (minimal erythemal doses) in a dawn to dusk exposure. Thus outdoor workers should be provided with UPF 30 clothing, or better. Results from recent experiments using SK-II hairless mice dressed in UPF 50 `sunsuits` have shown that the mice developed no sun induced skin cancers on the skin areas protected by the UPF 50 fabric whereas multiple tumours developed on the unprotected skin.

  19. Ultraviolet A1 phototherapy: One center's experience

    Directory of Open Access Journals (Sweden)

    Sasi Kiran Attili

    2017-01-01

    Full Text Available Background: Ultraviolet A1(UVA1 phototherapy is increasingly being used in the treatment of morphea, atopic dermatitis, lupus and some other recalcitrant dermatoses. We present a retrospective review of our experience with this modality. Aim: To evaluate the treatment response rates for various dermatoses and adverse effects of UVA1 phototherapy. Methods: We reviewed phototherapy notes along with electronic and/or paper case records for all patients treated with UVA1 phototherapy from October 1996 to December 2008. Results: A total of 269 patients (outcomes available for 247 had 361 treatment courses (treatment data available for 317 courses over this period. We found phototherapy to be beneficial in 28 (53% of 53 patients with atopic dermatitis and 19 (51% of 37 patients with morphea. A beneficial outcome was recorded in all six (100% cases of urticaria and six (85.7% of seven patients treated for a polymorphic light eruption. Benefit was also recorded in systemic lupus erythematosus (8 (44.4% of 18, lichen sclerosus (6 (42.9% of 14, mastocytosis (2 (33.3% of 6, necrobiosis lipoidica (4 (30.8% of 13, granuloma annulare (2 (25% of 8, scleroderma (2 (22.2% of 9 and keloids (1 (7.7% of 13. Overall, treatment was well tolerated with no patients having to stop treatment due to adverse effects. Limitations: This is a retrospective study with no control group. Subjective/recall bias is quite possible as a number of patients were followed up over the phone. Conclusions: Our data suggest that ultraviolet A1 can be considered for the treatment of selected dermatoses. However, long-term malignancy risk is as yet unknown.

  20. Protection from solar ultraviolet radiation by clothing

    International Nuclear Information System (INIS)

    Pailthorpe, M.

    1996-01-01

    The recently published Australia/New Zealand Standard AS/NZS 4399: l996 'Sun Protective Clothing - Evaluation and Classification' specifies an in vitro spectrophotometric method for the measurement of the ultraviolet (WR) transmission of textiles. Ultraviolet Protection Factors (UPF) are then calculated by convolving the UVR transmission data with standard CIE erythemal response data and ARL solar irradiance data. At the present time the scope of the standard is limited to loose fitting dry clothing. Virtually every textile parameter has an influence on the UPF of the finished garment and hence on the protection afforded to skin from the harmful effects of solar UVR radiation. Textile parameters such as fibre type, the method of spinning the yarn, fabric structure, cover factor, colorant, UVR absorbers and finishing methods determine the UPF of the fabric and hence must be controlled from batch to batch. Since garments generally shrink when washed, multiple wearing and washing cycles usually cause an increase in fabric UPF. Adventitious soiling of fabrics and the absorption of certain components of domestic laundry formulations, e g fluorescent whitening agents, increase fabric UPF ratings. Garments with a high degree of elasticity, e g nylon/lycra sportswear, that are stretched on to fit, will obviously have lower UPFs when stretched than when relaxed. In general fabrics worn in a wet state provide lower protection than when worn dry. On Australia's most extreme summer day it has been estimated that there are 30 MEDs (minimal erythemal doses) in a dawn to dusk exposure. Thus outdoor workers should be provided with UPF 30 clothing, or better. Results from recent experiments using SK-II hairless mice dressed in UPF 50 'sunsuits' have shown that the mice developed no sun induced skin cancers on the skin areas protected by the UPF 50 fabric whereas multiple tumours developed on the unprotected skin

  1. Controlling excitons. Concepts for phosphorescent organic LEDs at high brightness

    Energy Technology Data Exchange (ETDEWEB)

    Reineke, Sebastian

    2009-11-15

    This work focusses on the high brightness performance of phosphorescent organic light-emitting diodes (OLEDs). The use of phosphorescent emitter molecules in OLEDs is essential to realize internal electron-photon conversion efficiencies of 100 %. However, due to their molecular nature, the excited triplet states have orders of magnitude longer time constants compared to their fluorescent counterparts which, in turn, strongly increases the probability of bimolecular annihilation. As a consequence, the efficiencies of phosphorescent OLEDs decline at high brightness - an effect known as efficiency roll-off, for which it has been shown to be dominated by triplet-triplet annihilation (TTA). In this work, TTA of the archetype phosphorescent emitter Ir(ppy){sub 3} is investigated in time-resolved photoluminescence experiments. For the widely used mixed system CBP:Ir(ppy){sub 3}, host-guest TTA - an additional unwanted TTA channel - is experimentally observed at high excitation levels. By using matrix materials with higher triplet energies, this effect is efficiently suppressed, however further studies show that the efficiency roll-off of Ir(ppy)3 is much more pronounced than predicted by a model based on Foerster-type energy transfer, which marks the intrinsic limit for TTA. These results suggest that the emitter molecules show a strong tendency to form aggregates in the mixed film as the origin for enhanced TTA. Transmission electron microscopy images of Ir(ppy){sub 3} doped mixed films give direct proof of emitter aggregates. Based on these results, two concepts are developed that improve the high brightness performance of OLEDs. In a first approach, thin intrinsic matrix interlayers are incorporated in the emission layer leading to a one-dimensional exciton confinement that suppresses exciton migration and, consequently, TTA. The second concept reduces the efficiency roll-off by using an emitter molecule with slightly different chemical structure, i.e. Ir(ppy){sub 2

  2. High Brightness Neutron Source for Radiography. Final report

    International Nuclear Information System (INIS)

    Cremer, J.T.; Piestrup, Melvin A.; Gary, Charles K.; Harris, Jack L.; Williams, David J.; Jones, Glenn E.; Vainionpaa, J.H.; Fuller, Michael J.; Rothbart, George H.; Kwan, J.W.; Ludewigt, B.A.; Gough, R.A.; Reijonen, Jani; Leung, Ka-Ngo

    2008-01-01

    This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases

  3. Hi-C Observations of Penumbral Bright Dots

    Science.gov (United States)

    Alpert, S. E.; Tiwari, S. K.; Moore, R. L.; Savage, S. L.; Winebarger, A. R.

    2014-01-01

    We use high-quality data obtained by the High Resolution Coronal Imager (Hi-C) to examine bright dots (BDs) in a sunspot's penumbra. The sizes of these BDs are on the order of 1 arcsecond (1") and are therefore hard to identify using the Atmospheric Imaging Assembly's (AIA) 0.6" pixel(exp -1) resolution. These BD become readily apparent with Hi-C's 0.1" pixel(exp -1) resolution. Tian et al. (2014) found penumbral BDs in the transition region (TR) by using the Interface Region Imaging Spectrograph (IRIS). However, only a few of their dots could be associated with any enhanced brightness in AIA channels. In this work, we examine the characteristics of the penumbral BDs observed by Hi-C in a sunspot penumbra, including their sizes, lifetimes, speeds, and intensity. We also attempt to find any association of these BDs to the IRIS BDs. There are fewer Hi-C BDs in the penumbra than seen by IRIS, though different sunspots were studied. We use 193 Angstroms Hi-C data from July 11, 2012 which observed from approximately 18:52:00 UT- 18:56:00 UT and supplement it with data from AIA's 193 Angstrom passband to see the complete lifetime of the dots that were born before and/or lasted longer than Hi- C's 5-minute observation period. We use additional AIA passbands and compare the light curves of the BDs at different temperatures to test whether the Hi-C BDs are TR BDs. We find that most Hi-C BDs show clear movement, and of those that do, they move in a radial direction, toward or away from the sunspot umbra. Single BDs interact with other BDs, combining to fade away or brighten. The BDs that do not interact with other BDs tend to move less. Many of the properties of our BDs are similar to the extreme values of the IRIS BDs, e.g., they move slower on average and their sizes and lifetimes are on the higher end of the IRIS BDs. We infer that our penumbral BDs are the large-scale end of the distribution of BDs observed by IRIS.

  4. Transient events in bright debris discs: Collisional avalanches revisited

    Science.gov (United States)

    Thebault, P.; Kral, Q.

    2018-01-01

    Context. A collisional avalanche is set off by the breakup of a large planetesimal, releasing vast amounts of small unbound grains that enter a debris disc located further away from the star, triggering there a collisional chain reaction that could potentially create detectable transient structures. Aims: We investigate this mechanism, using for the first time a fully self-consistent code coupling dynamical and collisional evolutions. We also quantify for the first time the photometric evolution of the system and investigate whether or not avalanches could explain the short-term luminosity variations recently observed in some extremely bright debris discs. Methods: We use the state-of-the-art LIDT-DD code. We consider an avalanche-favoring A6V star, and two set-ups: a "cold disc" case, with a dust release at 10 au and an outer disc extending from 50 to 120 au, and a "warm disc" case with the release at 1 au and a 5-12 au outer disc. We explore, in addition, two key parameters: the density (parameterized by its optical depth τ) of the main outer disc and the amount of dust released by the initial breakup. Results: We find that avalanches could leave detectable structures on resolved images, for both "cold" and "warm" disc cases, in discs with τ of a few 10-3, provided that large dust masses (≳1020-5 × 1022 g) are initially released. The integrated photometric excess due to an avalanche is relatively limited, less than 10% for these released dust masses, peaking in the λ 10-20 μm domain and becoming insignificant beyond 40-50 μm. Contrary to earlier studies, we do not obtain stronger avalanches when increasing τ to higher values. Likewise, we do not observe a significant luminosity deficit, as compared to the pre-avalanche level, after the passage of the avalanche. These two results concur to make avalanches an unlikely explanation for the sharp luminosity drops observed in some extremely bright debris discs. The ideal configuration for observing an

  5. ASAS-SN Discovery of a Bright Be Star Undergoing a Possible Outburst

    Science.gov (United States)

    Jayasinghe, T.; Stanek, K. Z.; Kochanek, C. S.; Thorstensen, J.; Rupert, J.; Prieto, J. L.; Shields, J. V.; Thompson, T. A.; Holoien, T. W.-S.; Shappee, B. J.; Dong, Subo

    2017-09-01

    As part of an ongoing effort by ASAS-SN project (Shappee et al. 2014; Kochanek et al. 2017) to characterize and catalog all bright variable stars (e.g., Jayasinghe et al. 2017, ATel #10634, #10677), we report the discovery of a bright Be star undergoing a possible outburst.

  6. Properties of bright solitons in averaged and unaveraged models for SDG fibres

    Science.gov (United States)

    Kumar, Ajit; Kumar, Atul

    1996-04-01

    Using the slowly varying envelope approximation and averaging over the fibre cross-section the evolution equation for optical pulses in semiconductor-doped glass (SDG) fibres is derived from the nonlinear wave equation. Bright soliton solutions of this equation are obtained numerically and their properties are studied and compared with those of the bright solitons in the unaveraged model.

  7. Short Pulse High Brightness X-ray Production with the PLEIADES Thomson Scattering Source

    International Nuclear Information System (INIS)

    Anderson, S.G.; Barty, C.P.J.; Betts, S.M.; Brown, W.J.; Crane, J.K.; Cross, R.R.; Fittinghoff, D.N.; Gibson, D.J.; Hartemann, F.V.; Kuba, J.; LaSage, G.P.; Rosenzweig, J.B.; Slaughter, D.R.; Springer, P.T.; Tremaine, A.M.

    2003-01-01

    We describe PLEIADES, a compact, tunable, high-brightness, ultra-short pulse, Thomson x-ray source. The peak brightness of the source is expected to exceed 10 20 photons/s/0.1% bandwidth/mm 2 /mrad 2 . Initial results are reported and compared to theoretical calculations

  8. T1 bright appendix sign to exclude acute appendicitis in pregnant women.

    Science.gov (United States)

    Shin, Ilah; An, Chansik; Lim, Joon Seok; Kim, Myeong-Jin; Chung, Yong Eun

    2017-08-01

    To evaluate the diagnostic value of the T1 bright appendix sign for the diagnosis of acute appendicitis in pregnant women. This retrospective study included 125 pregnant women with suspected appendicitis who underwent magnetic resonance (MR) imaging. The T1 bright appendix sign was defined as a high intensity signal filling more than half length of the appendix on T1-weighted imaging. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the T1 bright appendix sign for normal appendix identification were calculated in all patients and in those with borderline-sized appendices (6-7 mm). The T1 bright appendix sign was seen in 51% of patients with normal appendices, but only in 4.5% of patients with acute appendicitis. The overall sensitivity, specificity, PPV, and NPV of the T1 bright appendix sign for normal appendix diagnosis were 44.9%, 95.5%, 97.6%, and 30.0%, respectively. All four patients with borderline sized appendix with appendicitis showed negative T1 bright appendix sign. The T1 bright appendix sign is a specific finding for the diagnosis of a normal appendix in pregnant women with suspected acute appendicitis. • Magnetic resonance imaging is increasingly used in emergency settings. • Acute appendicitis is the most common cause of acute abdomen. • Magnetic resonance imaging is widely used in pregnant population. • T1 bright appendix sign can be a specific sign representing normal appendix.

  9. SKY BRIGHTNESS AND TRANSPARENCY IN THE i-BAND AT DOME A, ANTARCTICA

    International Nuclear Information System (INIS)

    Zou Hu; Zhou Xu; Jiang Zhaoji; Hu Jingyao; Ma Jun; Ashley, M. C. B.; Luong-Van, D. M.; Storey, J. W. V.; Cui Xiangqun; Feng Longlong; Gong Xuefei; Kulesa, C. A.; Lawrence, J. S.; Liu Genrong; Moore, A. M.; Pennypacker, C. R.; Travouillon, T.; Qin Weijia; Sun Bo; Shang Zhaohui

    2010-01-01

    The i-band observing conditions at Dome A on the Antarctic plateau have been investigated using data acquired during 2008 with the Chinese Small Telescope Array. The sky brightness, variations in atmospheric transparency, cloud cover, and the presence of aurorae are obtained from these images. The median sky brightness of moonless clear nights is 20.5 mag arcsec -2 in the SDSS i band at the south celestial pole (which includes a contribution of about 0.06 mag from diffuse Galactic light). The median over all Moon phases in the Antarctic winter is about 19.8 mag arcsec -2 . There were no thick clouds in 2008. We model contributions of the Sun and the Moon to the sky background to obtain the relationship between the sky brightness and transparency. Aurorae are identified by comparing the observed sky brightness to the sky brightness expected from this model. About 2% of the images are affected by relatively strong aurorae.

  10. Tolerance of brightness and contrast adjustments on chronic apical abscess and apical granuloma interpretation

    Science.gov (United States)

    Purnamasari, L.; Iskandar, H. H. B.; Makes, B. N.

    2017-08-01

    In digitized radiography techniques, adjusting the image enhancement can improve the subjective image quality by optimizing the brightness and contrast for diagnostic needs. To determine the value range of image enhancement (brightness and contrast) on chronic apical abscess and apical granuloma interpretation. 30 periapical radiographs that diagnosed chronic apical abscess and 30 that diagnosed apical granuloma were adjusted by changing brightness and contrast values. The value range of brightness and contrast adjustment that can be tolerated in radiographic interpretations of chronic apical abscess and apical granuloma spans from -10 to +10. Brightness and contrast adjustments on digital radiographs do not affect the radiographic interpretation of chronic apical abscess and apical granuloma if conducted within the value range.

  11. High cortisol awakening response is associated with an impairment of the effect of bright light therapy

    DEFF Research Database (Denmark)

    Martiny, Klaus Per Juul; Lunde, Marianne Anita; Undén, M

    2009-01-01

    OBJECTIVE: We investigated the predictive validity of the cortisol awakening response (CAR) in patients with non-seasonal major depression. METHOD: Patients were treated with sertraline in combination with bright or dim light therapy for a 5-week period. Saliva cortisol levels were measured in 63...... patients, as an awakening profile, before medication and light therapy started. The CAR was calculated by using three time-points: awakening and 20 and 60 min after awakening. RESULTS: Patients with low CAR had a very substantial effect of bright light therapy compared with dim light therapy, whereas...... patients with a high CAR had no effect of bright light therapy compared with dim light therapy. CONCLUSION: High CAR was associated with an impairment of the effect of bright light therapy. This result raises the question of whether bright light acts through a mechanism different from...

  12. Tolerance of image enhancement brightness and contrast in lateral cephalometric digital radiography for Steiner analysis

    Science.gov (United States)

    Rianti, R. A.; Priaminiarti, M.; Syahraini, S. I.

    2017-08-01

    Image enhancement brightness and contrast can be adjusted on lateral cephalometric digital radiographs to improve image quality and anatomic landmarks for measurement by Steiner analysis. To determine the limit value for adjustments of image enhancement brightness and contrast in lateral cephalometric digital radiography for Steiner analysis. Image enhancement brightness and contrast were adjusted on 100 lateral cephalometric radiography in 10-point increments (-30, -20, -10, 0, +10, +20, +30). Steiner analysis measurements were then performed by two observers. Reliabilities were tested by the Interclass Correlation Coefficient (ICC) and significance tested by ANOVA or the Kruskal Wallis test. No significant differences were detected in lateral cephalometric analysis measurements following adjustment of the image enhancement brightness and contrast. The limit value of adjustments of the image enhancement brightness and contrast associated with incremental 10-point changes (-30, -20, -10, 0, +10, +20, +30) does not affect the results of Steiner analysis.

  13. Brightness measurement of an electron impact gas ion source for proton beam writing applications

    Energy Technology Data Exchange (ETDEWEB)

    Liu, N.; Santhana Raman, P. [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Xu, X.; Pang, R.; Kan, J. A. van, E-mail: phyjavk@nus.edu.sg [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Khursheed, A. [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore)

    2016-02-15

    We are developing a high brightness nano-aperture electron impact gas ion source, which can create ion beams from a miniature ionization chamber with relatively small virtual source sizes, typically around 100 nm. A prototype source of this kind was designed and successively micro-fabricated using integrated circuit technology. Experiments to measure source brightness were performed inside a field emission scanning electron microscope. The total output current was measured to be between 200 and 300 pA. The highest estimated reduced brightness was found to be comparable to the injecting focused electron beam reduced brightness. This translates into an ion reduced brightness that is significantly better than that of conventional radio frequency ion sources, currently used in single-ended MeV accelerators.

  14. A spectral k-means approach to bright-field cell image segmentation.

    Science.gov (United States)

    Bradbury, Laura; Wan, Justin W L

    2010-01-01

    Automatic segmentation of bright-field cell images is important to cell biologists, but difficult to complete due to the complex nature of the cells in bright-field images (poor contrast, broken halo, missing boundaries). Standard approaches such as level set segmentation and active contours work well for fluorescent images where cells appear as round shape, but become less effective when optical artifacts such as halo exist in bright-field images. In this paper, we present a robust segmentation method which combines the spectral and k-means clustering techniques to locate cells in bright-field images. This approach models an image as a matrix graph and segment different regions of the image by computing the appropriate eigenvectors of the matrix graph and using the k-means algorithm. We illustrate the effectiveness of the method by segmentation results of C2C12 (muscle) cells in bright-field images.

  15. The surface brightness of 1550 galaxies in Fornax: automated galaxy surface photometry: Pt. 2

    International Nuclear Information System (INIS)

    Phillipps, S.; Disney, M.J.; Kibblewhite, E.J.; Cawson, M.G.M.

    1987-01-01

    A survey of a complete sample of galaxies in the region of the Fornax cluster is presented. Measurements with the Automatic Plate Measuring machine are used to derive the observed distribution of galaxy surface brightness for 1550 objects. Corrections for surface brightness dependent selection effects are then made in order to estimate the true distribution. It is found that the sample (with 16.6 ≤ Msub(APM) ≤ 19.1) is divided into two distinct populations. The 'normal' galaxies with extrapolated central surface brightness Ssub(x) ≤ 22.5 Bμ form a uniformly distributed background of field galaxies. Low surface brightness galaxies (Ssub(x) ≥ 22.5 Bμ), on the other hand, are strongly clumped about the cluster centre. There appear to be few low surface brightness field galaxies. (author)

  16. Cross-dimensional mapping of number, length and brightness by preschool children.

    Directory of Open Access Journals (Sweden)

    Maria Dolores de Hevia

    Full Text Available Human adults in diverse cultures, children, infants, and non-human primates relate number to space, but it is not clear whether this ability reflects a specific and privileged number-space mapping. To investigate this possibility, we tested preschool children in matching tasks where the dimensions of number and length were mapped both to one another and to a third dimension, brightness. Children detected variation on all three dimensions, and they reliably performed mappings between number and length, and partially between brightness and length, but not between number and brightness. Moreover, children showed reliably better mapping of number onto the dimension of length than onto the dimension of brightness. These findings suggest that number establishes a privileged mapping with the dimension of length, and that other dimensions, including brightness, can be mapped onto length, although less efficiently. Children's adeptness at number-length mappings suggests that these two dimensions are intuitively related by the end of the preschool years.

  17. The new world atlas of artificial night sky brightness.

    Science.gov (United States)

    Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C M; Elvidge, Christopher D; Baugh, Kimberly; Portnov, Boris A; Rybnikova, Nataliya A; Furgoni, Riccardo

    2016-06-01

    Artificial lights raise night sky luminance, creating the most visible effect of light pollution-artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world's land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights.

  18. THE zCOSMOS 10k-BRIGHT SPECTROSCOPIC SAMPLE

    International Nuclear Information System (INIS)

    Lilly, Simon J.; Maier, Christian; Carollo, Marcella; Caputi, Karina; Le Brun, Vincent; Kneib, Jean-Paul; Le Fevre, Olivier; De la Torre, Sylvain; De Ravel, Loic; Mainieri, Vincenzo; Mignoli, Marco; Zamorani, Gianni; Bardelli, Sandro; Bolzonella, Micol; Coppa, Graziano; Scodeggio, Marco; Contini, Thierry; Renzini, Alvio; Bongiorno, Angela; Cucciati, Olga

    2009-01-01

    We present spectroscopic redshifts of a large sample of galaxies with I AB -1 , independent of redshift. The reliability of individual redshifts is described by a Confidence Class that has been empirically calibrated through repeat spectroscopic observations of over 600 galaxies. There is very good agreement between spectroscopic and photometric redshifts for the most secure Confidence Classes. For the less secure Confidence Classes, there is a good correspondence between the fraction of objects with a consistent photometric redshift and the spectroscopic repeatability, suggesting that the photometric redshifts can be used to indicate which of the less secure spectroscopic redshifts are likely right and which are probably wrong, and to give an indication of the nature of objects for which we failed to determine a redshift. Using this approach, we can construct a spectroscopic sample that is 99% reliable and which is 88% complete in the sample as a whole, and 95% complete in the redshift range 0.5 < z < 0.8. The luminosity and mass completeness levels of the zCOSMOS-bright sample of galaxies is also discussed.

  19. Advanced laser technologies for high-brightness photocathode electron gun

    International Nuclear Information System (INIS)

    Tomizawa, Hiromitsu

    2012-01-01

    A laser-excited photocathode RF gun is one of the most reliable high-brightness electron beam sources for XFELs. Several 3D laser shaping methods have been developed as ideal photocathode illumination sources at SPring-8 since 2001. To suppress the emittance growth caused by nonlinear space-charge forces, the 3D cylindrical UV-pulse was optimized spatially as a flattop and temporally as squarely stacked chirped pulses. This shaping system is a serial combination of a deformable mirror that adaptively shapes the spatial profile with a genetic algorithm and a UV-pulse stacker that consists of four birefringent α-BBO crystal rods for temporal shaping. Using this 3D-shaped pulse, a normalized emittance of 1.4 πmm mrad was obtained in 2006. Utilizing laser's Z-polarization, Schottky-effect-gated photocathode gun was proposed in 2006. The cathode work functions are reduced by a laser-induced Schottky effect. As a result of focusing a radially polarized laser pulse with a hollow lens in vacuum, the Z-field (Z-polarization) is generated at the cathode. (author)

  20. Temporal intensity interferometry: photon bunching in three bright stars

    Science.gov (United States)

    Guerin, W.; Dussaux, A.; Fouché, M.; Labeyrie, G.; Rivet, J.-P.; Vernet, D.; Vakili, F.; Kaiser, R.

    2017-12-01

    We report the first intensity correlation measured with starlight since the historical experiments of Hanbury Brown and Twiss. The photon bunching g(2)(τ, r = 0), obtained in the photon-counting regime, was measured for three bright stars: α Boo, α CMi and β Gem. The light was collected at the focal plane of a 1-m optical telescope, transported by a multi-mode optical fibre, split into two avalanche photodiodes and correlated digitally in real time. For total exposure times of a few hours, we obtained contrast values around 2 × 10-3, in agreement with the expectation for chaotic sources, given the optical and electronic bandwidths of our set-up. Comparing our results with the measurement of Hanbury Brown et al. for α CMi, we argue for the timely opportunity to extend our experiments to measuring the spatial correlation function over existing and/or foreseen arrays of optical telescopes diluted over several kilometres. This would enable microarcsec long-baseline interferometry in the optical, especially in the visible wavelengths, with a limiting magnitude of 10.

  1. On Quasi-Periodic Brightness Variations of P Cygni

    Science.gov (United States)

    Kochiashvili, N.; Beradze, S.; Natsvlishvili, R.; Kochiashvili, I.; Vardosanidze, M.; Pannicke, A.

    2018-03-01

    Until recent decades, it was considered that all Luminous Blue Variables are single massive and high luminosity stars. Now for several of them a companion has been found. The opinion exists that P Cygni also has a companion with an orbital period of about seven years. In accordance with this hypothesis, a known powerful eruption occurred near the periastron point. P Cygni, as well as several other well-known Luminous Blue Variable (LBV) stars, is a so-called "Supernova Impostor" because it survived after a powerful outburst. However, there were cases during the last decade when a LBV star survived after a powerful giant eruption, and then after a few years, explode as a supernova. Because the real reason for the great eruption and characteristic light variability of LBV, including P Cygni, is not established yet, any kind of photometric and spectral observational data is very significant. We present the results of analysis of the long-term photometric observations of hypergiant P Cygni. On the basis of these data, different quasi-periodic brightness changes of the star were revealed.

  2. High Brightness HDR Projection Using Dynamic Freeform Lensing

    KAUST Repository

    Damberg, Gerwin

    2016-05-03

    Cinema projectors need to compete with home theater displays in terms of image quality. High frame rate and spatial resolution as well as stereoscopic 3D are common features today, but even the most advanced cinema projectors lack in-scene contrast and, more important, high peak luminance, both of which are essential perceptual attributes of images appearing realistic. At the same time, HDR image statistics suggest that the average image intensity in a controlled ambient viewing environment such as the cinema can be as low as 1% for cinematic HDR content and not often higher than 18%, middle gray in photography. Traditional projection systems form images and colors by blocking the source light from a lamp, therefore attenuating between 99% and 82% of light, on average. This inefficient use of light poses significant challenges for achieving higher peak brightness levels. In this work, we propose a new projector architecture built around commercially available components, in which light can be steered to form images. The gain in system efficiency significantly reduces the total cost of ownership of a projector (fewer components and lower operating cost), and at the same time increases peak luminance and improves black level beyond what is practically achievable with incumbent projector technologies. At the heart of this computational display technology is a new projector hardware design using phase modulation in combination with a new optimization algorithm that is capable of on-the-fly computation of freeform lens surfaces. © 2016 ACM.

  3. The First Post-Kepler Brightness Dips of KIC 8462852

    Science.gov (United States)

    Boyajian, Tabetha. S.; Alonso, Roi; Ammerman, Alex; Armstrong, David; Asensio Ramos, A.; Barkaoui, K.; Beatty, Thomas G.; Benkhaldoun, Z.; Benni, Paul; Bentley, Rory O.; Berdyugin, Andrei; Berdyugina, Svetlana; Bergeron, Serge; Bieryla, Allyson; Blain, Michaela G.; Capetillo Blanco, Alicia; Bodman, Eva H. L.; Boucher, Anne; Bradley, Mark; Brincat, Stephen M.; Brink, Thomas G.; Briol, John; Brown, David J. A.; Budaj, J.; Burdanov, A.; Cale, B.; Aznar Carbo, Miguel; Castillo García, R.; Clark, Wendy J.; Clayton, Geoffrey C.; Clem, James L.; Coker, Phillip H.; Cook, Evan M.; Copperwheat, Chris M.; Curtis, J. L.; Cutri, R. M.; Cseh, B.; Cynamon, C. H.; Daniels, Alex J.; Davenport, James R. A.; Deeg, Hans J.; De Lorenzo, Roberto; de Jaeger, Thomas; Desrosiers, Jean-Bruno; Dolan, John; Dowhos, D. J.; Dubois, Franky; Durkee, R.; Dvorak, Shawn; Easley, Lynn; Edwards, N.; Ellis, Tyler G.; Erdelyi, Emery; Ertel, Steve; Farfán, Rafael. G.; Farihi, J.; Filippenko, Alexei V.; Foxell, Emma; Gandolfi, Davide; Garcia, Faustino; Giddens, F.; Gillon, M.; González-Carballo, Juan-Luis; González-Fernández, C.; González Hernández, J. I.; Graham, Keith A.; Greene, Kenton A.; Gregorio, J.; Hallakoun, Na’ama; Hanyecz, Ottó; Harp, G. R.; Henry, Gregory W.; Herrero, E.; Hildbold, Caleb F.; Hinzel, D.; Holgado, G.; Ignácz, Bernadett; Ilyin, Ilya; Ivanov, Valentin D.; Jehin, E.; Jermak, Helen E.; Johnston, Steve; Kafka, S.; Kalup, Csilla; Kardasis, Emmanuel; Kaspi, Shai; Kennedy, Grant M.; Kiefer, F.; Kielty, C. L.; Kessler, Dennis; Kiiskinen, H.; Killestein, T. L.; King, Ronald A.; Kollar, V.; Korhonen, H.; Kotnik, C.; Könyves-Tóth, Réka; Kriskovics, Levente; Krumm, Nathan; Krushinsky, Vadim; Kundra, E.; Lachapelle, Francois-Rene; LaCourse, D.; Lake, P.; Lam, Kristine; Lamb, Gavin P.; Lane, Dave; Lau, Marie Wingyee; Lewin, Pablo; Lintott, Chris; Lisse, Carey; Logie, Ludwig; Longeard, Nicolas; Lopez Villanueva, M.; Whit Ludington, E.; Mainzer, A.; Malo, Lison; Maloney, Chris; Mann, A.; Mantero, A.; Marengo, Massimo; Marchant, Jon; Martínez González, M. J.; Masiero, Joseph R.; Mauerhan, Jon C.; McCormac, James; McNeely, Aaron; Meng, Huan Y. A.; Miller, Mike; Molnar, Lawrence A.; Morales, J. C.; Morris, Brett M.; Muterspaugh, Matthew W.; Nespral, David; Nugent, C. R.; Nugent, Katherine M.; Odasso, A.; O’Keeffe, Derek; Oksanen, A.; O’Meara, John M.; Ordasi, András; Osborn, Hugh; Ott, John J.; Parks, J. R.; Rodriguez Perez, Diego; Petriew, Vance; Pickard, R.; Pál, András; Plavchan, P.; Pollacco, Don; Pozo Nuñez, F.; Pozuelos, F. J.; Rau, Steve; Redfield, Seth; Relles, Howard; Ribas, Ignasi; Richards, Jon; Saario, Joonas L. O.; Safron, Emily J.; Sallai, J. Martin; Sárneczky, Krisztián; Schaefer, Bradley E.; Schumer, Clea F.; Schwartzendruber, Madison; Siegel, Michael H.; Siemion, Andrew P. V.; Simmons, Brooke D.; Simon, Joshua D.; Simón-Díaz, S.; Sitko, Michael L.; Socas-Navarro, Hector; Sódor, Á.; Starkey, Donn; Steele, Iain A.; Stone, Geoff; Strassmeier, Klaus G.; Street, R. A.; Sullivan, Tricia; Suomela, J.; Swift, J. J.; Szabó, Gyula M.; Szabó, Róbert; Szakáts, Róbert; Szalai, Tamás; Tanner, Angelle M.; Toledo-Padrón, B.; Tordai, Tamás; Triaud, Amaury H. M. J.; Turner, Jake D.; Ulowetz, Joseph H.; Urbanik, Marian; Vanaverbeke, Siegfried; Vanderburg, Andrew; Vida, Krisztián; Vietje, Brad P.; Vinkó, József; von Braun, K.; Waagen, Elizabeth O.; Walsh, Dan; Watson, Christopher A.; Weir, R. C.; Wenzel, Klaus; Westendorp Plaza, C.; Williamson, Michael W.; Wright, Jason T.; Wyatt, M. C.; Zheng, WeiKang; Zsidi, Gabriella

    2018-01-01

    We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in 2015 October, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1%–2.5% dips, named “Elsie,” “Celeste,” “Skara Brae,” and “Angkor,” which persist on timescales from several days to weeks. Our main results so far are as follows: (i) there are no apparent changes of the stellar spectrum or polarization during the dips and (ii) the multiband photometry of the dips shows differential reddening favoring non-gray extinction. Therefore, our data are inconsistent with dip models that invoke optically thick material, but rather they are in-line with predictions for an occulter consisting primarily of ordinary dust, where much of the material must be optically thin with a size scale ≪1 μm, and may also be consistent with models invoking variations intrinsic to the stellar photosphere. Notably, our data do not place constraints on the color of the longer-term “secular” dimming, which may be caused by independent processes, or probe different regimes of a single process.

  4. Precision Statistical Analysis of Images Based on Brightness Distribution

    Directory of Open Access Journals (Sweden)

    Muzhir Shaban Al-Ani

    2017-07-01

    Full Text Available Study the content of images is considered an important topic in which reasonable and accurate analysis of images are generated. Recently image analysis becomes a vital field because of huge number of images transferred via transmission media in our daily life. These crowded media with images lead to highlight in research area of image analysis. In this paper, the implemented system is passed into many steps to perform the statistical measures of standard deviation and mean values of both color and grey images. Whereas the last step of the proposed method concerns to compare the obtained results in different cases of the test phase. In this paper, the statistical parameters are implemented to characterize the content of an image and its texture. Standard deviation, mean and correlation values are used to study the intensity distribution of the tested images. Reasonable results are obtained for both standard deviation and mean value via the implementation of the system. The major issue addressed in the work is concentrated on brightness distribution via statistical measures applying different types of lighting.

  5. Advanced Laser Technologies for High-brightness Photocathode Electron Gun

    Science.gov (United States)

    Tomizawa, Hiromitsu

    A laser-excited photocathode RF gun is one of the most reliable high-brightness electron beam sources for XFELs. Several 3D laser shaping methods have been developed as ideal photocathode illumination sources at SPring-8 since 2001. To suppress the emittance growth caused by nonlinear space-charge forces, the 3D cylindrical UV-pulse was optimized spatially as a flattop and temporally as squarely stacked chirped pulses. This shaping system is a serial combination of a deformable mirror that adaptively shapes the spatial profile with a genetic algorithm and a UV-pulse stacker that consists of four birefringent α-BBO crystal rods for temporal shaping. Using this 3D-shaped pulse, a normalized emittance of 1.4 π mm mrad was obtained in 2006. Utilizing laser's Z-polarization, Schottky-effect-gated photocathode gun was proposed in 2006. The cathode work functions are reduced by a laser-induced Schottky effect. As a result of focusing a radially polarized laser pulse with a hollow lens in vacuum, the Z-field (Z-polarization) is generated at the cathode.

  6. Low Cost Lithography Tool for High Brightness LED Manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Andrew Hawryluk; Emily True

    2012-06-30

    The objective of this activity was to address the need for improved manufacturing tools for LEDs. Improvements include lower cost (both capital equipment cost reductions and cost-ofownership reductions), better automation and better yields. To meet the DOE objective of $1- 2/kilolumen, it will be necessary to develop these highly automated manufacturing tools. Lithography is used extensively in the fabrication of high-brightness LEDs, but the tools used to date are not scalable to high-volume manufacturing. This activity addressed the LED lithography process. During R&D and low volume manufacturing, most LED companies use contact-printers. However, several industries have shown that these printers are incompatible with high volume manufacturing and the LED industry needs to evolve to projection steppers. The need for projection lithography tools for LED manufacturing is identified in the Solid State Lighting Manufacturing Roadmap Draft, June 2009. The Roadmap states that Projection tools are needed by 2011. This work will modify a stepper, originally designed for semiconductor manufacturing, for use in LED manufacturing. This work addresses improvements to yield, material handling, automation and throughput for LED manufacturing while reducing the capital equipment cost.

  7. Bright Soil Near 'McCool': Salty Deja Vu?

    Science.gov (United States)

    2006-01-01

    While driving eastward toward the northwestern flank of 'McCool Hill,' the wheels of NASA's Mars Exploration Rover Spirit churned up the largest amount of bright soil discovered so far in the mission. This image from Spirit's navigation camera, taken on the rover's 787th Martian day, or sol, of exploration (March 21, 2006), shows the strikingly light tone and large extent of the deposit. A few days earlier, Spirit's wheels unearthed a small patch of light-toned material informally named 'Tyrone.' In images from Spirit's panoramic camera, 'Tyrone' strongly resembled both 'Arad' and 'Paso Robles,' two patches of light-toned soils discovered earlier in the mission. Spirit found 'Paso Robles' in 2005 while climbing 'Cumberland Ridge' on the western slope of 'Husband Hill.' In early January 2006, the rover discovered 'Arad' on the basin floor just south of 'Husband Hill.' Spirit's instruments confirmed that those soils had a salty chemistry dominated by iron-bearing sulfates. Spirit's miniature thermal emission spectrometer is analyzing this most recent discovery, and researchers will compare it with those other deposits. These discoveries indicate that light-toned soil deposits might be widely distributed on the flanks and valley floors of the 'Columbia Hills' region in Gusev Crater on Mars. The salts may record the past presence of water, as they are easily mobilized and concentrated in liquid solution.

  8. A giant planet undergoing extreme-ultraviolet irradiation by its hot massive-star host.

    Science.gov (United States)

    Gaudi, B Scott; Stassun, Keivan G; Collins, Karen A; Beatty, Thomas G; Zhou, George; Latham, David W; Bieryla, Allyson; Eastman, Jason D; Siverd, Robert J; Crepp, Justin R; Gonzales, Erica J; Stevens, Daniel J; Buchhave, Lars A; Pepper, Joshua; Johnson, Marshall C; Colon, Knicole D; Jensen, Eric L N; Rodriguez, Joseph E; Bozza, Valerio; Novati, Sebastiano Calchi; D'Ago, Giuseppe; Dumont, Mary T; Ellis, Tyler; Gaillard, Clement; Jang-Condell, Hannah; Kasper, David H; Fukui, Akihiko; Gregorio, Joao; Ito, Ayaka; Kielkopf, John F; Manner, Mark; Matt, Kyle; Narita, Norio; Oberst, Thomas E; Reed, Phillip A; Scarpetta, Gaetano; Stephens, Denice C; Yeigh, Rex R; Zambelli, Roberto; Fulton, B J; Howard, Andrew W; James, David J; Penny, Matthew; Bayliss, Daniel; Curtis, Ivan A; DePoy, D L; Esquerdo, Gilbert A; Gould, Andrew; Joner, Michael D; Kuhn, Rudolf B; Labadie-Bartz, Jonathan; Lund, Michael B; Marshall, Jennifer L; McLeod, Kim K; Pogge, Richard W; Relles, Howard; Stockdale, Christopher; Tan, T G; Trueblood, Mark; Trueblood, Patricia

    2017-06-22

    The amount of ultraviolet irradiation and ablation experienced by a planet depends strongly on the temperature of its host star. Of the thousands of extrasolar planets now known, only six have been found that transit hot, A-type stars (with temperatures of 7,300-10,000 kelvin), and no planets are known to transit the even hotter B-type stars. For example, WASP-33 is an A-type star with a temperature of about 7,430 kelvin, which hosts the hottest known transiting planet, WASP-33b (ref. 1); the planet is itself as hot as a red dwarf star of type M (ref. 2). WASP-33b displays a large heat differential between its dayside and nightside, and is highly inflated-traits that have been linked to high insolation. However, even at the temperature of its dayside, its atmosphere probably resembles the molecule-dominated atmospheres of other planets and, given the level of ultraviolet irradiation it experiences, its atmosphere is unlikely to be substantially ablated over the lifetime of its star. Here we report observations of the bright star HD 195689 (also known as KELT-9), which reveal a close-in (orbital period of about 1.48 days) transiting giant planet, KELT-9b. At approximately 10,170 kelvin, the host star is at the dividing line between stars of type A and B, and we measure the dayside temperature of KELT-9b to be about 4,600 kelvin. This is as hot as stars of stellar type K4 (ref. 5). The molecules in K stars are entirely dissociated, and so the primary sources of opacity in the dayside atmosphere of KELT-9b are probably atomic metals. Furthermore, KELT-9b receives 700 times more extreme-ultraviolet radiation (that is, with wavelengths shorter than 91.2 nanometres) than WASP-33b, leading to a predicted range of mass-loss rates that could leave the planet largely stripped of its envelope during the main-sequence lifetime of the host star.

  9. High performance organic integrated device with ultraviolet photodetective and electroluminescent properties consisting of a charge-transfer-featured naphthalimide derivative

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hanyu; Wang, Xu; Yu, Junsheng, E-mail: luzhiyun@scu.edu.cn, E-mail: jsyu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhou, Jie; Lu, Zhiyun, E-mail: luzhiyun@scu.edu.cn, E-mail: jsyu@uestc.edu.cn [College of Chemistry, Sichuan University, Chengdu 610064 (China)

    2014-08-11

    A high performance organic integrated device (OID) with ultraviolet photodetective and electroluminescent (EL) properties was fabricated by using a charge-transfer-featured naphthalimide derivative of 6-(3,5-bis-[9-(4-t-butylphenyl)-9H-carbazol-3-yl]-phenoxy)-2- (4-t-butylphenyl)-benzo[de]isoquinoline-1,3-dione (CzPhONI) as the active layer. The results showed that the OID had a high detectivity of 1.5 × 10{sup 11} Jones at −3 V under the UV-350 nm illumination with an intensity of 0.6 mW/cm{sup 2}, and yielded an exciplex EL light emission with a maximum brightness of 1437 cd/m{sup 2}. Based on the energy band diagram, both the charge transfer feature of CzPhONI and matched energy level alignment were responsible for the dual ultraviolet photodetective and EL functions of OID.

  10. Mapping the solar wind HI outflow velocity in the inner heliosphere by coronagraphic ultraviolet and visible-light observations

    Science.gov (United States)

    Dolei, S.; Susino, R.; Sasso, C.; Bemporad, A.; Andretta, V.; Spadaro, D.; Ventura, R.; Antonucci, E.; Abbo, L.; Da Deppo, V.; Fineschi, S.; Focardi, M.; Frassetto, F.; Giordano, S.; Landini, F.; Naletto, G.; Nicolini, G.; Nicolosi, P.; Pancrazzi, M.; Romoli, M.; Telloni, D.

    2018-05-01

    We investigated the capability of mapping the solar wind outflow velocity of neutral hydrogen atoms by using synergistic visible-light and ultraviolet observations. We used polarised brightness images acquired by the LASCO/SOHO and Mk3/MLSO coronagraphs, and synoptic Lyα line observations of the UVCS/SOHO spectrometer to obtain daily maps of solar wind H I outflow velocity between 1.5 and 4.0 R⊙ on the SOHO plane of the sky during a complete solar rotation (from 1997 June 1 to 1997 June 28). The 28-days data sequence allows us to construct coronal off-limb Carrington maps of the resulting velocities at different heliocentric distances to investigate the space and time evolution of the outflowing solar plasma. In addition, we performed a parameter space exploration in order to study the dependence of the derived outflow velocities on the physical quantities characterising the Lyα emitting process in the corona. Our results are important in anticipation of the future science with the Metis instrument, selected to be part of the Solar Orbiter scientific payload. It was conceived to carry out near-sun coronagraphy, performing for the first time simultaneous imaging in polarised visible-light and ultraviolet H I Lyα line, so providing an unprecedented view of the solar wind acceleration region in the inner corona. The movie (see Sect. 4.2) is available at https://www.aanda.org

  11. Exposure to ultraviolet radiation: recommendations for cosmetic use

    International Nuclear Information System (INIS)

    Dias, C.; Carvalho, F.R.S.

    2000-01-01

    The beginning of the so-called tanning industry made possible the acquisition of a tanned skin independently of the available solar radiation. The tan is produced by ultraviolet radiation and, as well as in solar exposure, there are additional risks on the use of the so-called sun-beds. The damaging effects of ultraviolet exposure are well documented and reasonably quantified. The objective of this paper is to inform the potential effects of ultraviolet radiation exposure in sun-beds and to provide recommendations in order to reduce the associated risks. These recommendations are adapted for cosmetics use only (author)

  12. Biological applications of ultraviolet free-electron lasers

    International Nuclear Information System (INIS)

    Sutherland, J.C.

    1997-10-01

    This review examines the possibilities for biological research using the three ultraviolet free-electron lasers that are nearing operational status in the US. The projected operating characteristics of major interest in biological research of the free-electron lasers at Brookhaven National Laboratory, the Thomas Jefferson National Accelerator Facility, and Duke University are presented. Experimental applications in the areas of far- and vacuum ultraviolet photophysics and photochemistry, structural biology, environmental photobiology, and medical research are discussed and the prospects for advances in these areas, based upon the characteristics of the new ultraviolet free-electron lasers, are evaluated

  13. EVIDENCE FOR A WIDE RANGE OF ULTRAVIOLET OBSCURATION IN z {approx} 2 DUSTY GALAXIES FROM THE GOODS-HERSCHEL SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Penner, Kyle [Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States); Dickinson, Mark; Dey, Arjun; Kartaltepe, Jeyhan [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Pope, Alexandra [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Magnelli, Benjamin [Max Planck Institut fuer Extraterrestrische Physik, Postfach 1312, D-85741 Garching (Germany); Pannella, Maurilio; Aussel, Herve; Daddi, Emanuele; Elbaz, David [Laboratoire AIM Paris-Saclay, CEA/DSM/Irfu-CNRS-Universite Paris Diderot, CEA-Saclay, pt courrier 131, F-91191 Gif-sur-Yvette (France); Altieri, Bruno; Coia, Daniela [Herschel Science Center, European Space Astronomy Center, Villanueva de la Canada, E-28691 Madrid (Spain); Buat, Veronique [Laboratoire d' Astrophysique de Marseille, OAMP, Universite Aix-marseille, CNRS, 38 rue Frederic Joliot-Curie, F-13388 Marseille Cedex 13 (France); Bussmann, Shane; Hwang, Ho Seong [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Charmandaris, Vassilis [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, GR-71003 Heraklion (Greece); Dannerbauer, Helmut [Institut fuer Astronomie, Universitaet Wien, Tuerkenschanzstrasse 17, A-1180 Vienna (Austria); Lin Lihwai [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 106, Taiwan (China); Magdis, Georgios [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Morrison, Glenn, E-mail: kpenner@as.arizona.edu [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); and others

    2012-11-01

    Dusty galaxies at z {approx} 2 span a wide range of relative brightness between rest-frame mid-infrared (8 {mu}m) and ultraviolet wavelengths. We attempt to determine the physical mechanism responsible for this diversity. Dust-obscured galaxies (DOGs), which have rest-frame mid-IR to UV flux density ratios {approx}> 1000, might be abnormally bright in the mid-IR, perhaps due to prominent emission from active galactic nuclei and/or polycyclic aromatic hydrocarbons, or abnormally faint in the UV. We use far-infrared data from the GOODS-Herschel survey to show that most DOGs with 10{sup 12} L {sub Sun} {approx}< L {sub IR} {approx}< 10{sup 13} L {sub Sun} are not abnormally bright in the mid-IR when compared to other dusty galaxies with similar IR (8-1000 {mu}m) luminosities. We observe a relation between the median IR to UV luminosity ratios and the median UV continuum power-law indices for these galaxies, and we find that only 24% have specific star formation rates that indicate the dominance of compact star-forming regions. This circumstantial evidence supports the idea that the UV- and IR-emitting regions in these galaxies are spatially coincident, which implies a connection between the abnormal UV faintness of DOGs and dust obscuration. We conclude that the range in rest-frame mid-IR to UV flux density ratios spanned by dusty galaxies at z {approx} 2 is due to differing amounts of UV obscuration. Of galaxies with these IR luminosities, DOGs are the most obscured. We attribute differences in UV obscuration to either (1) differences in the degree of alignment between the spatial distributions of dust and massive stars or (2) differences in the total dust content.

  14. Extreme ultraviolet spectral irradiance measurements since 1946

    Science.gov (United States)

    Schmidtke, G.

    2015-03-01

    In the physics of the upper atmosphere the solar extreme ultraviolet (EUV) radiation plays a dominant role controlling most of the thermospheric/ionospheric (T/I) processes. Since this part of the solar spectrum is absorbed in the thermosphere, platforms to measure the EUV fluxes became only available with the development of rockets reaching altitude levels exceeding 80 km. With the availability of V2 rockets used in space research, recording of EUV spectra started in 1946 using photographic films. The development of pointing devices to accurately orient the spectrographs toward the sun initiated intense activities in solar-terrestrial research. The application of photoelectric recording technology enabled the scientists placing EUV spectrometers aboard satellites observing qualitatively strong variability of the solar EUV irradiance on short-, medium-, and long-term scales. However, as more measurements were performed more radiometric EUV data diverged due to the inherent degradation of the EUV instruments with time. Also, continuous recording of the EUV energy input to the T/I system was not achieved. It is only at the end of the last century that there was progress made in solving the serious problem of degradation enabling to monitore solar EUV fluxes with sufficient radiometric accuracy. The data sets available allow composing the data available to the first set of EUV data covering a period of 11 years for the first time. Based on the sophisticated instrumentation verified in space, future EUV measurements of the solar spectral irradiance (SSI) are promising accuracy levels of about 5% and less. With added low-cost equipment, real-time measurements will allow providing data needed in ionospheric modeling, e.g., for correcting propagation delays of navigation signals from space to earth. Adding EUV airglow and auroral emission monitoring by airglow cameras, the impact of space weather on the terrestrial T/I system can be studied with a spectral terrestrial

  15. THE NEAR-ULTRAVIOLET LUMINOSITY FUNCTION OF YOUNG, EARLY M-TYPE DWARF STARS

    International Nuclear Information System (INIS)

    Ansdell, Megan; Baranec, Christoph; Gaidos, Eric; Mann, Andrew W.; Lépine, Sebastien; James, David; Buccino, Andrea; Mauas, Pablo; Petrucci, Romina; Law, Nicholas M.; Riddle, Reed

    2015-01-01

    Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter the chemistry of planetary atmospheres, and a quantitative description of the evolution of NUV emission from M dwarfs is needed when modeling these effects. We investigated the NUV luminosity evolution of early M-type dwarfs by cross-correlating the Lépine and Gaidos catalog of bright M dwarfs with the Galaxy Evolution Explorer (GALEX) catalog of NUV (1771-2831 Å) sources. Of the 4805 sources with GALEX counterparts, 797 have NUV emission significantly (>2.5σ) in excess of an empirical basal level. We inspected these candidate active stars using visible-wavelength spectra, high-resolution adaptive optics imaging, time-series photometry, and literature searches to identify cases where the elevated NUV emission is due to unresolved background sources or stellar companions; we estimated the overall occurrence of these ''false positives'' (FPs) as ∼16%. We constructed an NUV luminosity function that accounted for FPs, detection biases of the source catalogs, and GALEX upper limits. We found the NUV luminosity function to be inconsistent with predictions from a constant star-formation rate and simplified age-activity relation defined by a two-parameter power law

  16. TEMPERATURE AND EXTREME-ULTRAVIOLET INTENSITY IN A CORONAL PROMINENCE CAVITY AND STREAMER

    Energy Technology Data Exchange (ETDEWEB)

    Kucera, T. A. [NASA/GSFC, Code 671, Greenbelt, MD 20771 (United States); Gibson, S. E.; Schmit, D. J. [HAO/NCAR, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Landi, E. [Department of Atmospheric, Oceanic and Space Science, Space Research Building, University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109-2143 (United States); Tripathi, D. [Inter-University Centre for Astronomy and Astrophysics, Post Bag-4, Ganeshkhind, Pune University Campus, Pune 411 007 (India)

    2012-09-20

    We analyze the temperature and EUV line emission of a coronal cavity and surrounding streamer in terms of a morphological forward model. We use a series of iron line ratios observed with the Hinode Extreme-ultraviolet Imaging Spectrograph (EIS) on 2007 August 9 to constrain temperature as a function of altitude in a morphological forward model of the streamer and cavity. We also compare model predictions to the EIS EUV line intensities and polarized brightness (pB) data from the Mauna Loa Solar Observatory (MLSO) Mark 4 K-coronameter. This work builds on earlier analysis using the same model to determine geometry of and density in the same cavity and streamer. The fit to the data with altitude-dependent temperature profiles indicates that both the streamer and cavity have temperatures in the range 1.4-1.7 MK. However, the cavity exhibits substantial substructure such that the altitude-dependent temperature profile is not sufficient to completely model conditions in the cavity. Coronal prominence cavities are structured by magnetism so clues to this structure are to be found in their plasma properties. These temperature substructures are likely related to structures in the cavity magnetic field. Furthermore, we find that the model overestimates the EUV line intensities by a factor of 4-10, without overestimating pB. We discuss this difference in terms of filling factors and uncertainties in density diagnostics and elemental abundances.

  17. Far Ultraviolet Spectroscopic Explorer Observations of the Supernova Remnant N49 in the Large Magellanic Cloud

    CERN Document Server

    Blair, W P; Shelton, R; Sembach, K R; Moos, H W; Raymond, J C; York, D G; Feldman, P D; Chayer, P; Murphy, E M; Sahnow, D J; Wilkinson, E; Blair, William P.; Sankrit, Ravi; Shelton, Robin; Sembach, Kenneth R.; Raymond, John C.; York, Donald G.; Feldman, Paul D.; Chayer, Pierre; Murphy, Edward M.; Sahnow, David J.; Wilkinson, Erik

    2001-01-01

    We report a Far Ultraviolet Spectroscopic Explorer satellite observation of the supernova remnant N49 in the Large Magellanic Cloud, covering the 905 -- 1187 A spectral region. A 30'' square aperture was used, resulting in a velocity resolution of ~100 km/s. The purpose of the observation was to examine several bright emission lines expected from earlier work and to demonstrate diffuse source sensitivity by searching for faint lines never seen previously in extragalactic supernova remnant UV spectra. Both goals were accomplished. Strong emission lines of O VI 1031.9 A, 1037.6 A and C III 977.0 A were seen, Doppler broadened to +/- 225 km/s and with centroids red-shifted to 350 km/s, consistent with the LMC. Superimposed on the emission lines are absorptions by C III and O VI 1031.9 at +260 km/s, which are attributed to warm and hot gas (respectively) in the LMC. The O VI 1037.6 A line is more severely affected by overlying interstellar and H2 absorption from both the LMC and our galaxy. N III 989.8 A is not s...

  18. THE NEAR-ULTRAVIOLET LUMINOSITY FUNCTION OF YOUNG, EARLY M-TYPE DWARF STARS

    Energy Technology Data Exchange (ETDEWEB)

    Ansdell, Megan; Baranec, Christoph [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Gaidos, Eric [Department of Geology and Geophysics, University of Hawaii, Honolulu, HI 96822 (United States); Mann, Andrew W. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Lépine, Sebastien [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302 (United States); James, David [Cerro Tololo Inter-American Observatory, Casilla 603 La Serena (Chile); Buccino, Andrea; Mauas, Pablo; Petrucci, Romina [Instituto de Astronomía y Física del Espacio, C1428EHA Buenos Aires (Argentina); Law, Nicholas M. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Riddle, Reed [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)

    2015-01-01

    Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter the chemistry of planetary atmospheres, and a quantitative description of the evolution of NUV emission from M dwarfs is needed when modeling these effects. We investigated the NUV luminosity evolution of early M-type dwarfs by cross-correlating the Lépine and Gaidos catalog of bright M dwarfs with the Galaxy Evolution Explorer (GALEX) catalog of NUV (1771-2831 Å) sources. Of the 4805 sources with GALEX counterparts, 797 have NUV emission significantly (>2.5σ) in excess of an empirical basal level. We inspected these candidate active stars using visible-wavelength spectra, high-resolution adaptive optics imaging, time-series photometry, and literature searches to identify cases where the elevated NUV emission is due to unresolved background sources or stellar companions; we estimated the overall occurrence of these ''false positives'' (FPs) as ∼16%. We constructed an NUV luminosity function that accounted for FPs, detection biases of the source catalogs, and GALEX upper limits. We found the NUV luminosity function to be inconsistent with predictions from a constant star-formation rate and simplified age-activity relation defined by a two-parameter power law.

  19. HST/STIS ULTRAVIOLET SPECTROSCOPY OF THE COMPONENTS OF THE MASSIVE TRIPLE STAR δ ORI A

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, Noel D.; Moffat, Anthony F. J. [Département de physique and Centre de Recherche en Astrophysique du Québec (CRAQ), Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec, H3C 3J7 (Canada); Gull, Theodore R.; Lindler, Don J. [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gies, Douglas R. [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 5060, Atlanta, GA 30302-5060 (United States); Corcoran, Michael F. [CRESST and X-ray Astrophysics Laboratory NASA/GSFC, Greenbelt, MD 20771 (United States); Chené, André-Nicolas, E-mail: richardson@astro.umontreal.ca, E-mail: moffat@astro.umontreal.ca, E-mail: theodore.r.gull@nasa.gov, E-mail: don.j.lindler@nasa.gov, E-mail: gies@chara.gsu.edu, E-mail: michael.f.corcoran@nasa.gov, E-mail: achene@gemini.edu [Gemini Observatory, Northern Operations Center, 670 North A’ohoku Place, Hilo, HI 96720 (United States)

    2015-07-20

    The multiple star system of δ Orionis is one of the closest examples of a system containing a luminous O-type, bright giant star (component Aa1). It is often used as a spectral-type standard and has the highest observed X-ray flux of any hot-star binary. The main component Aa1 is orbited by two lower mass stars, faint Aa2 in a 5.7 day eclipsing binary, and Ab, an astrometric companion with an estimated period of 346 years. Generally the flux from all three stars is recorded in ground-based spectroscopy, and the spectral decomposition of the components has proved difficult. Here we present Hubble Space Telescope/Space Telescope Imaging Spectrograph ultraviolet spectroscopy of δ Ori A that provides us with spatially separated spectra of Aa and Ab for the first time. We measured radial velocities for Aa1 and Ab in two observations made near the velocity extrema of Aa1. We show tentative evidence for the detection of the Aa2 component in cross-correlation functions of the observed and model spectra. We discuss the appearance of the UV spectra of Aa1 and Ab with reference to model spectra. Both stars have similar effective temperatures, but Ab is fainter and is a rapid rotator. The results will help in the interpretation of ground-based spectroscopy and in understanding the physical and evolutionary parameters of these massive stars.

  20. High brightness diode lasers controlled by volume Bragg gratings

    Science.gov (United States)

    Glebov, Leonid

    2017-02-01

    Volume Bragg gratings (VBGs) recorded in photo-thermo-refractive (PTR) glass are holographic optical elements that are effective spectral and angular filters withstanding high power laser radiation. Reflecting VBGs are narrow-band spectral filters while transmitting VBGs are narrow-band angular filters. The use of these optical elements in external resonators of semiconductor lasers enables extremely resonant feedback that provides dramatic spectral and angular narrowing of laser diodes radiation without significant power and efficiency penalty. Spectral narrowing of laser diodes by reflecting VBGs demonstrated in wide spectral region from near UV to 3 μm. Commercially available VBGs have spectral width ranged from few nanometers to few tens of picometers. Efficient spectral locking was demonstrated for edge emitters (single diodes, bars, modules, and stacks), vertical cavity surface emitting lasers (VCSELs), grating coupled surface emitting lasers (GCSELs), and interband cascade lasers (ICLs). The use of multiplexed VBGs provides multiwavelength emission from a single emitter. Spectrally locked semiconductor lasers demonstrated CW power from milliwatts to a kilowatt. Angular narrowing by transmitting VBGs enables single transverse mode emission from wide aperture diode lasers having resonators with great Fresnel numbers. This feature provides close to diffraction limit divergence along a slow axis of wide stripe edge emitters. Radiation exchange between lasers by means of spatially profiled or multiplexed VBGs enables coherent combining of diode lasers. Sequence of VBGs or multiplexed VBGs enable spectral combining of spectrally narrowed diode lasers or laser modules. Thus the use of VBGs for diode lasers beam control provides dramatic increase of brightness.