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Sample records for bright green-emitting fluorescent

  1. UV-activated conversion of Hoechst 33258, DAPI, and Vybrant DyeCycle fluorescent dyes into blue-excited, green-emitting protonated forms.

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    Zurek-Biesiada, Dominika; Kędracka-Krok, Sylwia; Dobrucki, Jurek W

    2013-05-01

    Hoechst 33258, DAPI and Vybrant DyeCycle are commonly known DNA fluorescent dyes that are excited by UV and emit in the blue region of the spectrum of visible light. Conveniently, they leave the reminder of the spectrum for microscopy detection of other cellular targets labeled with probes emitting in green, yellow or red. However, an exposure of these dyes to UV induces their photoconversion and results in production of the forms of these dyes that are excited by blue light and show fluoresce maxima in green and a detectable fluorescence in yellow and orange regions of the spectrum. Photoconversion of Hoechst 33258 and DAPI is reversible and independent of the dye concentration or the presence of DNA. Spectrofluorimetry and mass spectrometry analyses indicate that exposure to UV induces protonation of Hoechst 33258 and DAPI.

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

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    Hur, Kwang-Ho; Mueller, Joachim D

    2015-01-01

    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.

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

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    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.

  4. Cell-free measurements of brightness of fluorescently labeled antibodies

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    Zhou, Haiying; Tourkakis, George; Shi, Dennis; Kim, David M.; Zhang, Hairong; Du, Tommy; Eades, William C.; Berezin, Mikhail Y.

    2017-02-01

    Validation of imaging contrast agents, such as fluorescently labeled imaging antibodies, has been recognized as a critical challenge in clinical and preclinical studies. As the number of applications for imaging antibodies grows, these materials are increasingly being subjected to careful scrutiny. Antibody fluorescent brightness is one of the key parameters that is of critical importance. Direct measurements of the brightness with common spectroscopy methods are challenging, because the fluorescent properties of the imaging antibodies are highly sensitive to the methods of conjugation, degree of labeling, and contamination with free dyes. Traditional methods rely on cell-based assays that lack reproducibility and accuracy. In this manuscript, we present a novel and general approach for measuring the brightness using antibody-avid polystyrene beads and flow cytometry. As compared to a cell-based method, the described technique is rapid, quantitative, and highly reproducible. The proposed method requires less than ten microgram of sample and is applicable for optimizing synthetic conjugation procedures, testing commercial imaging antibodies, and performing high-throughput validation of conjugation procedures.

  5. Near UV-Blue Excitable Green-Emitting Nanocrystalline Oxide

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    C. E. Rodríguez-García

    2011-01-01

    Full Text Available Green-emitting Eu-activated powders were produced by a two-stage method consisting of pressure-assisted combustion synthesis and postannealing in ammonia. The as-synthesized powders exhibited a red photoluminescence (PL peak located at =616 nm when excited with =395 nm UV. This emission peak corresponds to the 5D0→7F2 transition in Eu3+. After annealing in ammonia, the PL emission changed to an intense broad-band peak centered at =500 nm, most likely produced by 4f65d1→4f7 electronic transitions in Eu2+. This green-emitting phosphor has excitation band in the near UV-blue region (=300–450 nm. X-ray diffraction analysis reveals mainly the orthorhombic EuAlO3 and Al2O3 phases. Transmission electron microscopy observations showed that the grains are formed by faceted nanocrystals (~4 nm of polygonal shape. The excellent excitation and emission properties make these powders very promising to be used as phosphors in UV solid-state diodes coupled to activate white-emitting lamps.

  6. Bright field microscopy as an alternative to whole cell fluorescence in automated analysis of macrophage images.

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    Jyrki Selinummi

    Full Text Available BACKGROUND: Fluorescence microscopy is the standard tool for detection and analysis of cellular phenomena. This technique, however, has a number of drawbacks such as the limited number of available fluorescent channels in microscopes, overlapping excitation and emission spectra of the stains, and phototoxicity. METHODOLOGY: We here present and validate a method to automatically detect cell population outlines directly from bright field images. By imaging samples with several focus levels forming a bright field -stack, and by measuring the intensity variations of this stack over the -dimension, we construct a new two dimensional projection image of increased contrast. With additional information for locations of each cell, such as stained nuclei, this bright field projection image can be used instead of whole cell fluorescence to locate borders of individual cells, separating touching cells, and enabling single cell analysis. Using the popular CellProfiler freeware cell image analysis software mainly targeted for fluorescence microscopy, we validate our method by automatically segmenting low contrast and rather complex shaped murine macrophage cells. SIGNIFICANCE: The proposed approach frees up a fluorescence channel, which can be used for subcellular studies. It also facilitates cell shape measurement in experiments where whole cell fluorescent staining is either not available, or is dependent on a particular experimental condition. We show that whole cell area detection results using our projected bright field images match closely to the standard approach where cell areas are localized using fluorescence, and conclude that the high contrast bright field projection image can directly replace one fluorescent channel in whole cell quantification. Matlab code for calculating the projections can be downloaded from the supplementary site: http://sites.google.com/site/brightfieldorstaining.

  7. Development of bright fluorescent quadracyclic adenine analogues: TDDFT-calculation supported rational design

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    Foller Larsen, Anders; Dumat, Blaise; Wranne, Moa S.; Lawson, Christopher P.; Preus, Søren; Bood, Mattias; Gradén, Henrik; Marcus Wilhelmsson, L.; Grøtli, Morten

    2015-07-01

    Fluorescent base analogues (FBAs) comprise a family of increasingly important molecules for the investigation of nucleic acid structure and dynamics. We recently reported the quantum chemical calculation supported development of four microenvironment sensitive analogues of the quadracyclic adenine (qA) scaffold, the qANs, with highly promising absorptive and fluorescence properties that were very well predicted by TDDFT calculations. Herein, we report on the efficient synthesis, experimental and theoretical characterization of nine novel quadracyclic adenine derivatives. The brightest derivative, 2-CNqA, displays a 13-fold increased brightness (ɛΦF = 4500) compared with the parent compound qA and has the additional benefit of being a virtually microenvironment-insensitive fluorophore, making it a suitable candidate for nucleic acid incorporation and use in quantitative FRET and anisotropy experiments. TDDFT calculations, conducted on the nine novel qAs a posteriori, successfully describe the relative fluorescence quantum yield and brightness of all qA derivatives. This observation suggests that the TDDFT-based rational design strategy may be employed for the development of bright fluorophores built up from a common scaffold to reduce the otherwise costly and time-consuming screening process usually required to obtain useful and bright FBAs.

  8. Ultra-bright and stimuli-responsive fluorescent nanoparticles for bioimaging.

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    Battistelli, Giulia; Cantelli, Andrea; Guidetti, Gloria; Manzi, Jeannette; Montalti, Marco

    2016-01-01

    Fluorescent nanoparticles (NPs) are unique contrast agents for bioimaging. Examples of molecular-based fluorescent NPs with brightness similar or superior to semiconductor quantum dots have been reported. These ultra-bright NPs consist of a silica or polymeric matrix that incorporate the emitting dyes as individual moieties or aggregates and promise to be more biocompatible than semiconductor quantum dots. Ultra-bright materials result from heavy doping of the structural matrix, a condition that entails a close mutual proximity of the doping dyes. Ground state and excited state interactions between the molecular emitters yield aggregation-caused quenching (ACQ) and proximity-caused quenching (PCQ). In combination with Föster resonance energy transfer (FRET) ACQ and PCQ originate collective phenomena that produce amplified quenching of the nanoprobes. In this focus article, we discuss strategies to achieve ultra-bright nanoprobes avoiding ACQ and PCQ also exploiting aggregation-induced emission (AIE). Amplified quenching, on the other hand, is also proposed as a strategy to design stimuli-responsive fluorogenic probes through disaggregation-induced emission (DIE) in alternative to AIE. As an advantage, DIE consents to design stimuli-responsive materials starting from a large variety of precursors. On the contrary, AIE is characteristic of a limited number of species. Examples of stimuli-responsive fluorogenic probes based on DIE are discussed.

  9. An improved cerulean fluorescent protein with enhanced brightness and reduced reversible photoswitching.

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    Michele L Markwardt

    Full Text Available Cyan fluorescent proteins (CFPs, such as Cerulean, are widely used as donor fluorophores in Förster resonance energy transfer (FRET experiments. Nonetheless, the most widely used variants suffer from drawbacks that include low quantum yields and unstable flurorescence. To improve the fluorescence properties of Cerulean, we used the X-ray structure to rationally target specific amino acids for optimization by site-directed mutagenesis. Optimization of residues in strands 7 and 8 of the β-barrel improved the quantum yield of Cerulean from 0.48 to 0.60. Further optimization by incorporating the wild-type T65S mutation in the chromophore improved the quantum yield to 0.87. This variant, mCerulean3, is 20% brighter and shows greatly reduced fluorescence photoswitching behavior compared to the recently described mTurquoise fluorescent protein in vitro and in living cells. The fluorescence lifetime of mCerulean3 also fits to a single exponential time constant, making mCerulean3 a suitable choice for fluorescence lifetime microscopy experiments. Furthermore, inclusion of mCerulean3 in a fusion protein with mVenus produced FRET ratios with less variance than mTurquoise-containing fusions in living cells. Thus, mCerulean3 is a bright, photostable cyan fluorescent protein which possesses several characteristics that are highly desirable for FRET experiments.

  10. Very bright orange fluorescent plants: endoplasmic reticulum targeting of orange fluorescent proteins as visual reporters in transgenic plants

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    Mann David GJ

    2012-05-01

    Full Text Available Abstract Background The expression of fluorescent protein (FP genes as real-time visual markers, both transiently and stably, has revolutionized plant biotechnology. A palette of colors of FPs is now available for use, but the diversity has generally been underutilized in plant biotechnology. Because of the green and far-red autofluorescent properties of many plant tissues and the FPs themselves, red and orange FPs (RFPs, and OFPs, respectfully appear to be the colors with maximum utility in plant biotechnology. Within the color palette OFPs have emerged as the brightest FP markers in the visible spectra. This study compares several native, near-native and modified OFPs for their “brightness” and fluorescence, therefore, their usability as marker genes in transgenic plant tissues. Results The OFPs DsRed2, tdTomato, mOrange and pporRFP were all expressed under the control of the CaMV 35S promoter in agroinfiltration-mediated transient assays in Nicotiana benthamiana. Each of these, as well as endoplasmic reticulum (ER-targeted versions, were stably expressed in transgenic Nicotiana tabacum and Arabidopsis thaliana. Congruent results were observed between transient and stable assays. Our results demonstrated that there are several adequate OFP genes available for plant transformation, including the new pporRFP, an unaltered tetramer from the hard coral Porites porites. When the tandem dimer tdTomato and the monomeric mOrange were targeted to the ER, dramatic, ca. 3-fold, increase in plant fluorescence was observed. Conclusions From our empirical data, and a search of the literature, it appears that tdTomato-ER and mOrange-ER are the two highest fluorescing FPs available as reporters for transgenic plants. The pporRFP is a brightly fluorescing tetramer, but all tetramer FPs are far less bright than the ER-targeted monomers we report here.

  11. Augmented microscopy: real-time overlay of bright-field and near-infrared fluorescence images.

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    Watson, Jeffrey R; Gainer, Christian F; Martirosyan, Nikolay; Skoch, Jesse; Lemole, G Michael; Anton, Rein; Romanowski, Marek

    2015-10-01

    Intraoperative applications of near-infrared (NIR) fluorescent contrast agents can be aided by instrumentation capable of merging the view of surgical field with that of NIR fluorescence. We demonstrate augmented microscopy, an intraoperative imaging technique in which bright-field (real) and electronically processed NIR fluorescence (synthetic) images are merged within the optical path of a stereomicroscope. Under luminance of 100,000 lx, representing typical illumination of the surgical field, the augmented microscope detects 189 nM concentration of indocyanine green and produces a composite of the real and synthetic images within the eyepiece of the microscope at 20 fps. Augmentation described here can be implemented as an add-on module to visualize NIR contrast agents, laser beams, or various types of electronic data within the surgical microscopes commonly used in neurosurgical, cerebrovascular, otolaryngological, and ophthalmic procedures.

  12. Structural analysis of the bright monomeric yellow-green fluorescent protein mNeonGreen obtained by directed evolution.

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    Clavel, Damien; Gotthard, Guillaume; von Stetten, David; De Sanctis, Daniele; Pasquier, Hélène; Lambert, Gerard G; Shaner, Nathan C; Royant, Antoine

    2016-12-01

    Until recently, genes coding for homologues of the autofluorescent protein GFP had only been identified in marine organisms from the phyla Cnidaria and Arthropoda. New fluorescent-protein genes have now been found in the phylum Chordata, coding for particularly bright oligomeric fluorescent proteins such as the tetrameric yellow fluorescent protein lanYFP from Branchiostoma lanceolatum. A successful monomerization attempt led to the development of the bright yellow-green fluorescent protein mNeonGreen. The structures of lanYFP and mNeonGreen have been determined and compared in order to rationalize the directed evolution process leading from a bright, tetrameric to a still bright, monomeric fluorescent protein. An unusual discolouration of crystals of mNeonGreen was observed after X-ray data collection, which was investigated using a combination of X-ray crystallography and UV-visible absorption and Raman spectroscopies, revealing the effects of specific radiation damage in the chromophore cavity. It is shown that X-rays rapidly lead to the protonation of the phenolate O atom of the chromophore and to the loss of its planarity at the methylene bridge.

  13. Green-emitting (La,M,Tb)OCl (M = Mg, Ca, and Sr) phosphors

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    Kim, Sun Woog; Jyoko, Kazuya; Masui, Toshiyuki; Imanaka, Nobuhito

    2012-12-01

    Green-emitting (La1-x-yMxTby)OCl (0 ⩽ x ⩽ 0.13, 0.03 ⩽ y ⩽ 0.15, M = Mg, Ca, and Sr) single phase phosphors were synthesized using a liquid-phase method and their photoluminescence properties were characterized. The excitation spectrum consisted of a strong broad band from 220 to 290 nm, which corresponds to the 4f-5d transition of Tb3+. The oxychloride phosphors exhibit typical emission peaks assigned to the transition from 5D4 to 7FJ (J = 6, 5, 4, and 3) of Tb3+, and the luminescence emission intensity was successfully enhanced by doping divalent alkaline earth metal ions (M = Mg2+, Ca2+, and Sr2+) into La3+ sites of the host LaOCl lattice. The highest green emission intensity was obtained for (La0.88Ca0.05Tb0.07)OCl, of which the relative emission intensity was 75% of that for a commercial green-emitting (La0.52Ce0.31Tb0.17)PO4 phosphor.

  14. Efficient yellow and green emitting InGaN/GaN nanostructured QW materials and LEDs

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    Nakajima, Yoshitake; Lin, Yenting; Dapkus, Paul Daniel [Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, CA, 90089 0243 (United States)

    2016-09-15

    Efficient green emitting LEDs and monolithic white light emitting LEDs require the extension of the range of efficient light emission in the GaN/InGaN materials system. We demonstrate high efficiency green and yellow light emitting multiple quantum well (MQW) structures grown on GaN nanostripe templates. The structures show promise for realizing high efficiency phosphor - free white LEDs. The nanostripe dimensions range from 100 to 300 nm and have separations that range from 300 nm to 1 μm. The MOCVD growth conditions strongly affect surfaces expressed in the GaN nanostripes whose sidewalls can be controlled to be nearly vertical or inclined and intersecting. Single quantum well (QW) structures are grown on these different stripes. Photoluminescence (PL) measurement shows that QW grown on stripes with the {10-11} surfaces and triangular shape emit the longest peak wavelength and highly efficient PL emission peak wavelengths as long as 570 nm are realized. PL and electroluminescence (EL) spectra show narrow linewidth that is comparable to the planar case and CL studies further demonstrate the uniform emission wavelength along the sidewalls of the structures. Finally, we have grown and fabricated green emitting LEDs on {10-11} faceted nanostripes with promising device characteristics. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Bright fluorescence monitoring system utilizing Zoanthus sp. green fluorescent protein (ZsGreen for human G-protein-coupled receptor signaling in microbial yeast cells.

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    Yasuyuki Nakamura

    Full Text Available G-protein-coupled receptors (GPCRs are currently the most important pharmaceutical targets for drug discovery because they regulate a wide variety of physiological processes. Consequently, simple and convenient detection systems for ligands that regulate the function of GPCR have attracted attention as powerful tools for new drug development. We previously developed a yeast-based fluorescence reporter ligand detection system using flow cytometry. However, using this conventional detection system, fluorescence from a cell expressing GFP and responding to a ligand is weak, making detection of these cells by fluorescence microscopy difficult. We here report improvements to the conventional yeast fluorescence reporter assay system resulting in the development of a new highly-sensitive fluorescence reporter assay system with extremely bright fluorescence and high signal-to-noise (S/N ratio. This new system allowed the easy detection of GPCR signaling in yeast using fluorescence microscopy. Somatostatin receptor and neurotensin receptor (implicated in Alzheimer's disease and Parkinson's disease, respectively were chosen as human GPCR(s. The facile detection of binding to these receptors by cognate peptide ligands was demonstrated. In addition, we established a highly sensitive ligand detection system using yeast cell surface display technology that is applicable to peptide screening, and demonstrate that the display of various peptide analogs of neurotensin can activate signaling through the neurotensin receptor in yeast cells. Our system could be useful for identifying lead peptides with agonistic activity towards targeted human GPCR(s.

  16. Characterization of Green-Emitting Translucent Zinc Oxide Ceramics Prepared Via Spark Plasma Sintering

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    Hong, Mei [University of California; DeVito, David M [ORNL; Howe, Jane Y [ORNL; Yang, Xiaocheng [West Virginia University; Giles, Nancy C. [Air Force Institute of Technology; Neal, John S [ORNL; Munir, Zuhair [University of California

    2011-01-01

    Translucent, green-emitting zinc oxide (ZnO) bodies, 19 mm in diameter and 0.72 mm in thickness, have been prepared via spark plasma sintering method. The consolidation of ZnO powders was investigated over the temperature range of 550-1050 C and the pressure range of 55-530 MPa. Samples sintered at temperatures >850 C and pressures of {approx}120 MPa were translucent and had densities of {approx}100%. Samples sintered at 950 C and 130 MPa showed a higher maximum transmittance than the samples sintered at higher or lower temperatures or pressures, with an excellent in-line transmission of 70% in the IR region around 2330 nm. The dense ZnO ceramics exhibited a strong green emission and a weak ultraviolet emission, and the relative intensity of the green emission increased with increasing sintering temperature.

  17. Directed evolution of a monomeric, bright and photostable version of Clavularia cyan fluorescent protein: structural characterization and applications in fluorescence imaging

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    Al, Hui-wang; Henderson, J. Nathan; Remington, S. James; Campbell, Robert E. (Alberta); (Oregon)

    2008-05-07

    The arsenal of engineered variants of the GFP [green FP (fluorescent protein)] from Aequorea jellyfish provides researchers with a powerful set of tools for use in biochemical and cell biology research. The recent discovery of diverse FPs in Anthozoa coral species has provided protein engineers with an abundance of alternative progenitor FPs from which improved variants that complement or supersede existing Aequorea GFP variants could be derived. Here, we report the engineering of the first monomeric version of the tetrameric CFP (cyan FP) cFP484 from Clavularia coral. Starting from a designed synthetic gene library with mammalian codon preferences, we identified dimeric cFP484 variants with fluorescent brightness significantly greater than the wild-type protein. Following incorporation of dimer-breaking mutations and extensive directed evolution with selection for blue-shifted emission, high fluorescent brightness and photostability, we arrived at an optimized variant that we have named mTFP1 [monomeric TFP1 (teal FP 1)]. The new mTFP1 is one of the brightest and most photostable FPs reported to date. In addition, the fluorescence is insensitive to physiologically relevant pH changes and the fluorescence lifetime decay is best fitted as a single exponential. The 1.19 {angstrom} crystal structure (1 {angstrom}=0.1 nm) of mTFP1 confirms the monomeric structure and reveals an unusually distorted chromophore conformation. As we experimentally demonstrate, the high quantum yield of mTFP1 (0.85) makes it particularly suitable as a replacement for ECFP (enhanced CFP) or Cerulean as a FRET (fluorescence resonance energy transfer) donor to either a yellow or orange FP acceptor.

  18. Uncovering Single-Molecule Photophysical Heterogeneity of Bright, Thermally Activated Delayed Fluorescence Emitters Dispersed in Glassy Hosts.

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    Noriega, Rodrigo; Barnard, Edward S; Ursprung, Benedikt; Cotts, Benjamin L; Penwell, Samuel B; Schuck, P James; Ginsberg, Naomi S

    2016-10-04

    Recently developed all-organic emitters used in display applications achieve high brightness by harvesting triplet populations via thermally activated delayed fluorescence. The photophysical properties of these emitters therefore involve new inherent complexities and are strongly affected by interactions with their host material in the solid state. Ensemble measurements occlude the molecular details of how host-guest interactions determine fundamental properties such as the essential balance of singlet oscillator strength and triplet harvesting. Therefore, using time-resolved fluorescence spectroscopy, we interrogate these emitters at the single-molecule level and compare their properties in two distinct glassy polymer hosts. We find that nonbonding interactions with aromatic moieties in the host appear to mediate the molecular configurations of the emitters, but also promote nonradiative quenching pathways. We also find substantial heterogeneity in the time-resolved photoluminescence of these emitters, which is dominated by static disorder in the polymer. Finally, since singlet-triplet cycling underpins the mechanism for increased brightness, we present the first room-temperature measurement of singlet-triplet equilibration dynamics in this family of emitters. Our observations present a molecular-scale interrogation of host-guest interactions in a disordered film, with implications for highly efficient organic light-emitting devices. Combining a single-molecule experimental technique with an emitter that is sensitive to triplet dynamics, yet read out via fluorescence, should also provide a complementary approach to performing fundamental studies of glassy materials over a large dynamic range of time scales.

  19. FluoroMyelin™ Red is a bright, photostable and non-toxic fluorescent stain for live imaging of myelin.

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    Monsma, Paula C; Brown, Anthony

    2012-08-15

    FluoroMyelin™ Red is a commercially available water-soluble fluorescent dye that has selectivity for myelin. This dye is marketed for the visualization of myelin in brain cryosections, though it is also used widely to stain myelin in chemically fixed tissue. Here we have investigated the suitability of FluoroMyelin™ Red as a vital stain for live imaging of myelin in myelinating co-cultures of Schwann cells and dorsal root ganglion neurons. We show that addition of FluoroMyelin™ Red to the culture medium results in selective staining of myelin sheaths, with an optimal staining time of 2h, and has no apparent adverse effect on the neurons, their axons, or the myelinating cells at the light microscopic level. The fluorescence is bright and photostable, permitting long-term time-lapse imaging. After rinsing the cultures with medium lacking FluoroMyelin™ Red, the dye diffuses out of the myelin with a half life of about 130 min resulting in negligible fluorescence remaining after 18-24h. In addition, the large Stokes shift exhibited by FluoroMyelin™ Red makes it possible to readily distinguish it from popular and widely used green and red fluorescent probes such as GFP and mCherry. Thus FluoroMyelin™ Red is a useful reagent for live fluorescence imaging studies on myelinated axons.

  20. Bright fluorescent chemosensor platforms for imaging endogenous pools of neuronal zinc.

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    Chang, Christopher J; Nolan, Elizabeth M; Jaworski, Jacek; Burdette, Shawn C; Sheng, Morgan; Lippard, Stephen J

    2004-02-01

    A series of new fluorescent Zinpyr (ZP) chemosensors based on the fluorescein platform have been prepared and evaluated for imaging neuronal Zn(2+). A systematic synthetic survey of electronegative substitution patterns on a homologous ZP scaffold provides a basis for tuning the fluorescence responses of "off-on" photoinduced electron transfer (PET) probes by controlling fluorophore pK(a) values and attendant proton-induced interfering fluorescence of the metal-free (apo) probes at physiological pH. We further establish the value of these improved optical tools for interrogating the metalloneurochemistry of Zn(2+); the novel ZP3 fluorophore images endogenous stores of Zn(2+) in live hippocampal neurons and slices, including the first fluorescence detection of Zn(2+) in isolated dentate gyrus cultures. Our findings reveal that careful control of fluorophore pK(a) can minimize proton-induced fluorescence of the apo probes and that electronegative substitution offers a general strategy for tuning PET chemosensors for cellular studies. In addition to providing improved optical tools for Zn(2+) in the neurosciences, these results afford a rational starting point for creating superior fluorescent probes for biological applications.

  1. Simultaneous fluorescence and high-resolution bright-field imaging with aberration correction over a wide field-of-view with Fourier ptychographic microscopy (FPM) (Conference Presentation)

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    Chung, Jaebum; Kim, Jinho; Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei

    2016-03-01

    We present a method to acquire both fluorescence and high-resolution bright-field images with correction for the spatially varying aberrations over a microscope's wide field-of-view (FOV). First, the procedure applies Fourier ptychographic microscopy (FPM) to retrieve the amplitude and phase of a sample, at a resolution that significantly exceeds the cutoff frequency of the microscope objective lens. At the same time, FPM algorithm is able to leverage on the redundancy within the set of acquired FPM bright-field images to estimate the microscope aberrations, which usually deteriorate in regions further away from the FOV's center. Second, the procedure acquires a raw wide-FOV fluorescence image within the same setup. Lack of moving parts allows us to use the FPM-estimated aberration map to computationally correct for the aberrations in the fluorescence image through deconvolution. Overlaying the aberration-corrected fluorescence image on top of the high-resolution bright-field image can be done with accurate spatial correspondence. This can provide means to identifying fluorescent regions of interest within the context of the sample's bright-field information. An experimental demonstration successfully improves the bright-field resolution of fixed, stained and fluorescently tagged HeLa cells by a factor of 4.9, and reduces the error caused by aberrations in a fluorescence image by 31%, over a field of view of 6.2 mm by 9.3 mm. For optimal deconvolution, we show the fluorescence image needs to have a signal-to-noise ratio of ~18.

  2. Molecular-Based Fluorescent Nanoparticles Built from Dedicated Dipolar Thienothiophene Dyes as Ultra-Bright Green to NIR Nanoemitters.

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    Mastrodonato, Cristiano; Pagano, Paolo; Daniel, Jonathan; Vaultier, Michel; Blanchard-Desce, Mireille

    2016-09-14

    Fluorescent Organic Nanoparticles (FONs), prepared by self-aggregation of dedicated dyes in water, represent a promising green alternative to the toxic quantum dots (QDs) for bioimaging purposes. In the present paper, we describe the synthesis and photophysical properties of new dipolar push-pull derivatives built from thieno[3,2-b]thiophene as a π-conjugated bridge that connects a triphenylamine moiety bearing various bulky substituents as electron-releasing moiety to acceptor end-groups of increasing strength (i.e., aldehyde, dicyanovinyl and diethylthiobarbiturate). All dyes display fluorescence properties in chloroform, which shifts from the green to the NIR range depending on the molecular polarization (i.e., strength of the end-groups) as well as a large two-photon absorption (TPA) band response in the biological spectral window (700-1000 nm). The TPA bands show a bathochromic shift and hyperchromic effect with increasing polarization of the dyes with maximum TPA cross-section reaching 2000 GM for small size chromophore. All dyes are found to form stable and deeply colored nanoparticles (20-45 nm in diameter) upon nanoprecipitation in water. Although their fluorescence is strongly reduced upon aggregation, all nanoparticles show large one-photon (up to 10⁸ M(-1)·cm(-1) in the visible region) and two-photon (up to 10⁶ GM in the NIR) brightness. Interestingly, both linear and non-linear optical properties are significantly affected by interchromophoric interactions, which are promoted by the molecular confinement and modulated by both the dipolar strength and the presence of the bulky groups. Finally, we exploited the photophysical properties of the FONs to design optimized core-shell nanoparticles built from a pair of complementary dipolar dyes that promotes an efficient core-to-shell FRET process. The resulting molecular-based core-shell nanoparticles combine large two-photon absorption and enhanced emission both located in the NIR spectral region

  3. Imaging magnetic scalar potentials by laser-induced fluorescence from bright and dark atoms

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    Fescenko, Ilja

    2014-01-01

    We present a spectroscopic method for mapping two-dimensional distributions of magnetic field strengths (magnetic scalar potential lines) using CCD recordings of the fluorescence patterns emitted by spin-polarized Cs vapor in a buffer gas exposed to inhomogeneous magnetic fields. The method relies on the position-selective destruction of spin polarization by magnetic resonances induced by multi-component oscillating magnetic fields, such that magnetic potential lines can directly be detected by the CCD camera. We also present a generic algebraic model allowing the calculation of the fluorescence patterns and find excellent agreement with the experimental observations for three distinct inhomogeneous field topologies. The spatial resolution obtained with these proof-of-principle experiments is on the order of 1 mm. A substantial increase of spatial and magnetic field resolution is expected by deploying the method in a magnetically shielded environment.

  4. Comparison of thin-layer chromatography, spectrofluorimetry and bright greenish-yellow fluorescence test for aflatoxin detection in corn

    Directory of Open Access Journals (Sweden)

    Elisabete Yurie Sataque Ono

    2010-06-01

    Full Text Available In this study the bright greenish-yellow fluorescence test, widely used by the corn milling industry, was compared to the thin-layer chromatography (TLC and spectrofluorimetry methods for aflatoxin detection in 40 corn samples naturally contaminated by the Aspergillus section Flavi. According to the corn processing industry criteria, all the samples were adequate for human and animal consumption by the bright greenish-yellow fluorescence test, but TLC and spectrofluorimetry analysis detected aflatoxins above the maximum tolerated limit (20 µg/kg in 7 and 8 samples, respectively. Aflatoxins were detected in 16 (40% corn samples by TLC, with levels ranging from 4.0 to 54.0 µg/kg (mean 19.97 ± 15.97 µg/kg, and in 25 (62.5% samples by spectrofluorimetry, with levels ranging from 1.0 to 58.66 µg/kg (mean 17.14 ± 17.81 µg/kg. The results indicated a good correlation (ρ = 0.97 between TLC and spectrofluorimetry for aflatoxin determination in naturally contaminated corn. The bright greenish-yellow fluorescence test was simple and quick, but it showed 20% false-negative results, suggesting its use only as screening method for detecting the suspected lots of grains that should be tested further for aflatoxin by more sensitive methods.Neste trabalho a contagem de fluorescência luminosa amarelo-esverdeada, amplamente utilizada pela indústria de processamento de milho, foi comparada à cromatografia em camada delgada (CCD e espectrofluorimetria para detecção de aflatoxinas em 40 amostras de milho naturalmente contaminadas por Aspergillus section Flavi. De acordo com os critérios da indústria processadora de milho, todas as amostras estavam adequadas para o consumo humano e animal pela contagem de fluorescência luminosa amarelo-esverdeada (CFLAE, porém as análises por CCD e espectrofluorimetria detectaram aflatoxinas acima do limite máximo tolerado (20 µg/kg em 7 e 8 amostras, respectivamente. As aflatoxinas foram detectadas em 16 (40

  5. Electronic structure and luminescence properties of Tb3+-activated NaBaBO3 green-emitting phosphor

    Institute of Scientific and Technical Information of China (English)

    郑将辉; 程其进; 吴顺情; 陈蓉; 蔡丽晗; 陈朝

    2015-01-01

    A novel green-emitting phosphor Tb3+doped NaBaBO3 was prepared using a conventional high temperature solid-state reaction method. The crystal structure and luminescence properties of NaBaBO3:Tb3+were studied. The NaBaBO3 host was also investigated using density functional theory calculations. Our calculated lattice parameters of NaBaBO3 host were found to be in excellent agreement with experiment. Theoretically, the host matrix NaBaBO3 was a wide-gap semiconductor with a direct band gap of 3.66 eV, where the bottom of conduction band and the top of valence band were dominated by Ba 5d state and O 2p state, respectively. The excitation spectra indicated that the phosphor could be effectively excited by near ultraviolet light. The phosphor featured a satisfactory green performance with the highest photoluminescence intensity located at 543 nm excited by 377 nm light and the measured Commission Internationale de L'Eclairage (CIE) chromaticity was determined to be (0.2860, 0.4640). The op-timum Tb3+concentration in NaBaBO3 was 5.0 mol.%. The concentration quenching occurred when Tb3+concentration was be-yond 5.0 mol.%and the concentration quenching mechanism could be explained by the dipole-dipole interaction. The effects of charge compensators (including Li+, Na+and K+) and temperature on the photoluminescence of NaBaBO3:Tb3+were also studied. The present work suggested that the NaBaBO3:Tb3+phosphor was a promising green-emitting material for near ultraviolet white light-emitting diodes.

  6. A stilbene that binds selectively to transthyretin in cells and remains dark until it undergoes a chemoselective reaction to create a bright blue fluorescent conjugate.

    Science.gov (United States)

    Choi, Sungwook; Ong, Derrick Sek Tong; Kelly, Jeffery W

    2010-11-17

    We describe a non-fluorescent, second generation stilbene that very selectively binds to transthyretin in complex biological environments and remains dark until it chemoselectively reacts with the pK(a)-perturbed Lys-15 ε-amino group of transthyretin to form a bright blue fluorescent conjugate. Stilbene A2 is mechanistically unusual in that it remains non-fluorescent in cell lysates lacking transthyretin, even though there is likely some proteome binding. Thus, it is especially useful for cellular imaging, as background fluorescence is undetectable until A2 reacts with transthyretin. The mechanistic basis for the effective lack of environment-sensitive fluorescence of A2 when bound to, but before reacting with, transthyretin is reported. Stilbene A2 exhibits sufficiently rapid transthyretin conjugation kinetics at 37 °C to enable pulse-chase experiments to be performed, in this case demonstrating that transthyretin is secreted from HeLa cells. As the chase compound, we employed C1, a cell-permeable, highly selective, non-covalent, transthyretin-binding dihydrostilbene that cannot become fluorescent. The progress reported is viewed as a first and necessary step toward our long-term goal of creating a one-chain, one-binding-site transthyretin tag, whose fluorescence can be regulated by adding A2 or an analogous molecule. Fusing proteins of interest to a one-chain, one-binding-site transthyretin tag regulated by A2 should be useful for studying folding, trafficking, and degradation in the cellular secretory pathway, utilizing pulse-chase experiments. Immediate applications of A2 include utilizing its conjugate fluorescence to quantify transthyretin concentration in human plasma, reflecting nutritional status, and determining the binding stoichiometry of kinetic stabilizer drugs to transthyretin in plasma.

  7. A bright water-compatible sugar-rhodamine fluorescence sensor for selective detection of Hg2+ in natural water and living cells.

    Science.gov (United States)

    Huang, Wei; Zhou, Peng; Yan, Wenbo; He, Cheng; Xiong, Liqin; Li, Fuyou; Duan, Chunying

    2009-02-01

    By combination of a sugar group and a rhodamine group into one molecule, a bright and specific fluorescent sensor for Hg(2+) in natural water and living cells was achieved. RG1 features the high quantum efficiency for a Hg(2+)-bound sensor in natural water and sensitivity to environmentally relevant mercury in complex natural samples. The limit of detection of Hg(2+) of 1 ppb level suggests that RG1 is capable of distinguishing between the safe and toxic levels of inorganic mercury in drinking water. RG1 also establishes excellent Hg(2+)-ion specificity over alkali-, alkaline-earth metals and the first-row transition metals as well as Pb(2+) and Ag(+). Investigation on the fluorescence imaging of Hg(2+) in living cells demonstrates that RG1 might be used for monitoring Hg(2+) within biological samples.

  8. Photochemical studies of a fluorescent chlorophyll catabolite--source of bright blue fluorescence in plant tissue and efficient sensitizer of singlet oxygen.

    Science.gov (United States)

    Jockusch, Steffen; Turro, Nicholas J; Banala, Srinivas; Kräutler, Bernhard

    2014-02-01

    Fluorescent chlorophyll catabolites (FCCs) are fleeting intermediates of chlorophyll breakdown, which is seen as an enzyme controlled detoxification process of the chlorophylls in plants. However, some plants accumulate large amounts of persistent FCCs, such as in senescent leaves and in peels of yellow bananas. The photophysical properties of such a persistent FCC (Me-sFCC) were investigated in detail. FCCs absorb in the near UV spectral region and show blue fluorescence (max at 437 nm). The Me-sFCC fluorescence had a quantum yield of 0.21 (lifetime 1.6 ns). Photoexcited Me-sFCC intersystem crosses into the triplet state (quantum yield 0.6) and generates efficiently singlet oxygen (quantum yield 0.59). The efficient generation of singlet oxygen makes fluorescent chlorophyll catabolites phototoxic, but might also be useful as a (stress) signal and for defense of the plant tissue against infection by pathogens.

  9. Vacuum Ultraviolet Spectral Investigations on Green-Emitting Ca(La,Gd)4Si3O13:Tb3+ Phosphors for PDP Applications

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In an effort to develop new green-emitting PDP phosphors with high efficiency, investigated were the synthesis, VUV photoluminescence (PL) spectra, optical properties, and chromaticity of Ca(La1-x-yTbxGdy)4Si3O13 phosphors by using synchrotron radiation. Upon analysis of the VUV spectroscopic and chromaticity investigations on the new green-emitting VUV phosphors, were an optimized composition achieved. The PLE spectral studies show that Ca(La1-x-yTbxGdy)4Si3O13 exhibit significant absorption in the VUV range. The VUV PL intensity was found to enhance with Gd3+-doping. Furthermore, the 1931 CIE chromaticity coordinates of Ca(La,Gd)4Si3O13:Tb were found to be (0.286, 0.548), as compared to (0.230, 0.712) for Zn2SiO4:Mn2+ as a reference. The potential application of Ca(La,Gd)4Si3O13:Tb as a new green-emitting PDP phosphor are being currently improving and evaluating.

  10. Fluorescence-guided surgery of retroperitoneal-implanted human fibrosarcoma in nude mice delays or eliminates tumor recurrence and increases survival compared to bright-light surgery.

    Directory of Open Access Journals (Sweden)

    Fuminari Uehara

    Full Text Available The aim of this study is to determine if fluorescence-guided surgery (FGS can eradicate human fibrosarcoma growing in the retroperitoneum of nude mice. One week after retroperitoneal implantation of human HT1080 fibrosarcoma cells, expressing green fluorescent protein (GFP (HT-1080-GFP, in nude mice, bright-light surgery (BLS was performed on all tumor-bearing mice (n = 22. After BLS, mice were randomized into 2 treatment groups; BLS-only (n = 11 or the combination of BLS + FGS (n = 11. The residual tumors remaining after BLS were resected with FGS using a hand-held portable imaging system under fluorescence navigation. The average residual tumor area after BLS + FGS was significantly smaller than after BLS-only (0.4 ± 0.4 mm(2 and 10.5 ± 2.4 mm(2, respectively; p = 0.006. Five weeks after surgery, the fluorescent-tumor areas of BLS- and BLS + FGS-treated mice were 379 ± 147 mm(2 and 11.7 ± 6.9 mm(2, respectively, indicating that FGS greatly inhibited tumor recurrence compared to BLS. The combination of BLS + FGS significantly decreased fibrosarcoma recurrence compared to BLS-only treated mice (p < 0.001. Mice treated with BLS+FGS had a significantly higher disease-free survival rate than mice treated with BLS-only at five weeks after surgery. These results suggest that combination of BLS + FGS significantly reduced the residual fibrosarcoma volume after BLS and improved disease-free survival.

  11. Spatially controlled fabrication of a bright fluorescent nanodiamond-array with enhanced far-red Si-V luminescence.

    Science.gov (United States)

    Singh, Sonal; Thomas, Vinoy; Martyshkin, Dmitry; Kozlovskaya, Veronika; Kharlampieva, Eugenia; Catledge, Shane A

    2014-01-31

    We demonstrate a novel approach to precisely pattern fluorescent nanodiamond-arrays with enhanced far-red intense photostable luminescence from silicon-vacancy (Si-V) defect centers. The precision-patterned pre-growth seeding of nanodiamonds is achieved by a scanning probe 'dip-pen' nanolithography technique using electrostatically driven transfer of nanodiamonds from 'inked' cantilevers to a UV-treated hydrophilic SiO2 substrate. The enhanced emission from nanodiamond dots in the far-red is achieved by incorporating Si-V defect centers in a subsequent chemical vapor deposition treatment. The development of a suitable nanodiamond ink and mechanism of ink transport, and the effect of humidity and dwell time on nanodiamond patterning are investigated. The precision patterning of as-printed (pre-CVD) arrays with dot diameter and dot height as small as 735 nm ± 27 nm and 61 nm ± 3 nm, respectively, and CVD-treated fluorescent ND-arrays with consistently patterned dots having diameter and height as small as 820 nm ± 20 nm and, 245 nm ± 23 nm, respectively, using 1 s dwell time and 30% RH is successfully achieved. We anticipate that the far-red intense photostable luminescence (~738 nm) observed from Si-V defect centers integrated in spatially arranged nanodiamonds could be beneficial for the development of next generation fluorescence-based devices and applications.

  12. Spatially controlled fabrication of a bright fluorescent nanodiamond-array with enhanced far-red Si-V luminescence

    Science.gov (United States)

    Singh, Sonal; Thomas, Vinoy; Martyshkin, Dmitry; Kozlovskaya, Veronika; Kharlampieva, Eugenia; Catledge, Shane A.

    2014-01-01

    We demonstrate a novel approach to precisely pattern fluorescent nanodiamond-arrays with enhanced far-red intense photostable luminescence from silicon-vacancy (Si-V) defect centers. The precision-patterned pre-growth seeding of nanodiamonds is achieved by a scanning probe ‘dip-pen’ nanolithography technique using electrostatically driven transfer of nanodiamonds from ‘inked’ cantilevers to a UV-treated hydrophilic SiO2 substrate. The enhanced emission from nanodiamond dots in the far-red is achieved by incorporating Si-V defect centers in a subsequent chemical vapor deposition treatment. The development of a suitable nanodiamond ink and mechanism of ink transport, and the effect of humidity and dwell time on nanodiamond patterning are investigated. The precision patterning of as-printed (pre-CVD) arrays with dot diameter and dot height as small as 735 nm ± 27 nm and 61 nm ± 3 nm, respectively, and CVD-treated fluorescent ND-arrays with consistently patterned dots having diameter and height as small as 820 nm ± 20 nm and, 245 nm ± 23 nm, respectively, using 1 s dwell time and 30% RH is successfully achieved. We anticipate that the far-red intense photostable luminescence (˜738 nm) observed from Si-V defect centers integrated in spatially arranged nanodiamonds could be beneficial for the development of next generation fluorescence-based devices and applications.

  13. Avaliação do método de triagem para análise de milho contaminado com aflatoxinas pela fluorescência amarelo-esverdeada brilhante (BGYF- Bright Greenish Yellow Fluorescence Evaluation of a screening method of aflatoxin in corn by Bright Greenish Yellow Fluorescence

    Directory of Open Access Journals (Sweden)

    M.E.T. PALOMINO

    1998-01-01

    Full Text Available A técnica da fluorescência amarelo-esverdeada brilhante (BGYF como método de triagem na avaliação de milho eventualmente contaminado com aflatoxina, utilizada por uma indústria alimentícia do Estado de São Paulo em 61 amostras de milho, foi comparada com a técnica BGYF padronizada, aplicada em laboratório antes e após trituração dos grãos e, também, com a técnica da cromatografia em camada delgada (CCD. Os resultados da indústria geraram menor número de resultados falso-positivos do que a técnica BGYF padronizada. Por outro lado, apenas os resultados da indústria apresentaram amostras falso-negativas, ao contrário da BGYF padronizada, que não as apresentou. Conclui-se que existe uma inadequação do número de pontos fluorescentes adotados como critério de rejeição em ambas as técnicas, devendo-se proceder estudos, com maior número de amostras, para determinar o número adequado de pontos fluorescentes a ser adotado como critério além de outros fatores que possam influenciar a metodologia.The bright greenish yellow fluorescence technique (BGYF is a screening method for the evaluation of corn occasionally contaminated by aflatoxins, used by an industry of the State of São Paulo on sixty one samples, was compared with laboratory results of the BGYF standard technique, before and after crushing the grains, and also with thin layer chromatographic analysis. The industry showed results with a smaller number of false positives than the BGYF standard technique. However, the industry showed false negative results and the BGYF standard technique did not. It was concluded that the number of fluorescent points adopted, as a rejection criterion, in both techniques, was inadequate and studies should be developed with more samples to determine the adequate number of fluorescent points to be adopted as a rejection criterion and the influence of other factors.

  14. A Bright Fluorescent Probe for H2S Enables Analyte-Responsive, 3D Imaging in Live Zebrafish Using Light Sheet Fluorescence Microscopy.

    Science.gov (United States)

    Hammers, Matthew D; Taormina, Michael J; Cerda, Matthew M; Montoya, Leticia A; Seidenkranz, Daniel T; Parthasarathy, Raghuveer; Pluth, Michael D

    2015-08-19

    Hydrogen sulfide (H2S) is a critical gaseous signaling molecule emerging at the center of a rich field of chemical and biological research. As our understanding of the complexity of physiological H2S in signaling pathways evolves, advanced chemical and technological investigative tools are required to make sense of this interconnectivity. Toward this goal, we have developed an azide-functionalized O-methylrhodol fluorophore, MeRho-Az, which exhibits a rapid >1000-fold fluorescence response when treated with H2S, is selective for H2S over other biological analytes, and has a detection limit of 86 nM. Additionally, the MeRho-Az scaffold is less susceptible to photoactivation than other commonly used azide-based systems, increasing its potential application in imaging experiments. To demonstrate the efficacy of this probe for H2S detection, we demonstrate the ability of MeRho-Az to detect differences in H2S levels in C6 cells and those treated with AOAA, a common inhibitor of enzymatic H2S synthesis. Expanding the use of MeRho-Az to complex and heterogeneous biological settings, we used MeRho-Az in combination with light sheet fluorescence microscopy (LSFM) to visualize H2S in the intestinal tract of live zebrafish. This application provides the first demonstration of analyte-responsive 3D imaging with LSFM, highlighting the utility of combining new probes and live imaging methods for investigating chemical signaling in complex multicellular systems.

  15. Luminescence properties of a novel green emitting Ba2CaZn2Si6O17:Eu2+ phosphor for white light - Emitting diodes applications

    Science.gov (United States)

    Annadurai, G.; Kennedy, S. Masilla Moses; Sivakumar, V.

    2016-05-01

    A novel green emitting Ba2CaZn2Si6O17:Eu2+ (BCZSO:Eu2+) phosphor was synthesized using conventional high temperature solid state reaction method. Powder X-ray diffraction was carried out to confirm the phase formation of the synthesized phosphors. Photoluminescence emission spectrum was recorded under excitation at 340 nm. The BCZSO:Eu2+ phosphor exhibited an intense asymmetric green emission band around 502 nm which originated from the 4f65d1 → 4f7 transition of Eu2+ ion. The optimum doping concentration of Eu2+ was found to be 0.06 mol. The energy transfer mechanism among Eu2+ in BCZSO phosphor was found to be a dipole-dipole interaction, and the critical distance (RC) for the Eu2+ ions calculated by the concentration quenching and spectral overlap methods were 23.2 Å and 13.7 Å, respectively. The decay curve of BCZSO:Eu2+ phosphors were discussed. The CIE chromaticity coordinate values (x = 0.259, y = 0.463) of BCZSO:Eu2+ phosphor were located in green region and the correlated color temperature was 7571 K. All these properties gave an indication that BCZSO:Eu2+ phosphor could be a potential green-emitting phosphor for UV based white light emitting diodes.

  16. Synthesis and luminescent properties of a novel green-emitting Tb(III) complex and the excellent thermal stability for application

    Science.gov (United States)

    Yuan, Chen; Xie, Hongde; Cai, Haijun; Chen, Cuili; Cai, Peiqing; Seo, Hyo Jin

    2016-04-01

    A green-emitting Tb(III) complex based on siloxane-modified pressure sensitive adhesives (SPSA-Tb(III)) was successfully synthesized by emulsion polymerization. Siloxane-modified pressure sensitive adhesives (SPSA) were used as host materials. The structural coordination, photoluminescence excitation (PLE) and luminescence (PL) spectra, and thermal characterization of this luminescent polymer were investigated. The result from the FT-IR spectra reveals that SPSA have successfully coordinated with the Tb(III) ions. The luminescent analysis indicates that SPSA-Tb(III) displays Tb(III) typical emission peaks at 489, 545, 583, and 622 nm under the excitation of 369 nm. When monitored at 545 nm, strong and sharp excitation bands appear from 300 to 500 nm. And SPSA-Tb(III) has short lifetime (0.25 ms). Meanwhile, SPSA-Tb(III) exhibits high thermal stability (Td = 402 °C) owing to the high bond dissociation energy of Sisbnd O bonds. All the results suggest that it is expected to be used as a superior green-emitting material under high temperature.

  17. Modulation of Exciton Generation in Organic Active Planar pn Heterojunction: Toward Low Driving Voltage and High-Efficiency OLEDs Employing Conventional and Thermally Activated Delayed Fluorescent Emitters.

    Science.gov (United States)

    Chen, Dongcheng; Liu, Kunkun; Gan, Lin; Liu, Ming; Gao, Kuo; Xie, Gaozhan; Ma, Yuguang; Cao, Yong; Su, Shi-Jian

    2016-08-01

    Organic light-emitting diodes (OLEDs) combining low driving voltage and high efficiency are designed by employing conventional and thermally activated delayed fluorescence emitters through modulation of excitons generated at the planar p-n heterojunction region. To date, this approach enables the highest power efficiency for yellow-green emitting fluorescent OLEDs with a simplified structure.

  18. Sustainable, Rapid Synthesis of Bright-Luminescent CuInS2-ZnS Alloyed Nanocrystals: Multistage Nano-xenotoxicity Assessment and Intravital Fluorescence Bioimaging in Zebrafish-Embryos

    Science.gov (United States)

    Chetty, S. Shashank; Praneetha, S.; Basu, Sandeep; Sachidanandan, Chetana; Murugan, A. Vadivel

    2016-05-01

    Near-infrared (NIR) luminescent CuInS2-ZnS alloyed nanocrystals (CIZS-NCs) for highly fluorescence bioimaging have received considerable interest in recent years. Owing, they became a desirable alternative to heavy-metal based-NCs and organic dyes with unique optical properties and low-toxicity for bioimaging and optoelectronic applications. In the present study, bright and robust CIZS-NCs have been synthesized within 5 min, as-high-as 230 °C without requiring any inert-gas atmosphere via microwave-solvothermal (MW-ST) method. Subsequently, the in vitro and in vivo nano-xenotoxicity and cellular uptake of the MUA-functionalized CIZS-NCs were investigated in L929, Vero, MCF7 cell lines and zebrafish-embryos. We observed minimal toxicity and acute teratogenic consequences upto 62.5 μg/ml of the CIZS-NCs in zebrafish-embryos. We also observed spontaneous uptake of the MUA-functionalized CIZS-NCs by 3 dpf older zebrafish-embryos that are evident through bright red fluorescence-emission at a low concentration of 7.8 μg/mL. Hence, we propose that the rapid, low-cost, large-scale “sustainable” MW-ST synthesis of CIZS-NCs, is an ideal bio-nanoprobe with good temporal and spatial resolution for rapid labeling, long-term in vivo tracking and intravital-fluorescence-bioimaging (IVBI).

  19. Novel green-emitting K2Ba5Si12O30:Eu2+ phosphors with excellent thermal quenching for white light-emitting diodes

    Science.gov (United States)

    Yeh, Kai-Yuan; Lin, Chia-Her; Maggay, Irish Valerie Buiser; Liu, Wei-Ren

    2016-09-01

    A novel green-emitting phosphor - K2Ba5Si12O30:Eu2+ (KBSO:Eu2+) was successfully synthesized via a solid state reaction. The crystal structure, luminescent properties as well as thermal quenching and LED fabrication were systematically carried out in this study. The emission and excitation spectra indicate that KBSO:Eu2+ phosphors exhibit broad excitation spectra ranging from 260 to 480 nm and an intense broad green emission at 497 nm under 370 nm excitation. The chromaticity coordinates of composition-optimized KBSO:Eu2+ phosphor is situated in the green region with coordinates (0.2404, 0.4429). The temperature-dependent photoluminescence demonstrates that KBSO:Eu2+ gives a good thermal quenching performance of ∼80% at 100 °C, which is much superior to that of commercial silicate-based phosphor of (Ba, Sr)2SiO4:Eu2+. Warm-white light-emitting diodes (LEDs) fabricated using an NUV-chip combined with the KBSO:3%Eu2+ phosphor gave color rendering indices 82.65, correlated color temperatures 4939 K, and the CIE chromaticity coordinates 0.3064, 0.3325). These results indicate that KBSO:Eu2+ is a potential green-emission phosphor for near UV and high powder white-light LEDs.

  20. Synthesis of high intensity green emitting (Ba,Sr)SiO4:Eu2+ phosphors through cellulose assisted liquid phase precursor process

    Science.gov (United States)

    Humayoun, Usama Bin; Song, Young-Hyun; Lee, MinJi; Masato, Kakihana; Abe, Hiroshi; Toda, Kenji; Sato, Yasushi; Masaki, Takaki; Yoon, Dae-Ho

    2016-01-01

    Green emitting phosphor (Ba1-x,Sr1-x)SiO4:2xEu2+, x = 0.03, 0.05, 0.1, and 0.15 were synthesized through a Liquid Phase Precursor Process (LPP). Liquid phase precursor method is reported to result in phosphors with markedly increased emission intensities compared to other synthesis methods. Here microcrystalline cellulose (MCC) and hydroxypropyl cellulose (HPC) templates were studied to achieve high efficiency green phosphors. The phase formation was investigated by XRD analysis which showed the conformation of the Ba2SiO4 (JCPDS card number 761631) phase. The obtained samples exhibited broad excitation spectra with maximum at 430 nm and a green emission centered around 520 nm. An optimized dopant concentration was selected and the effect of two different types of cellulose, i.e. MCC and HPC templates on the emission properties was considered. It was found that the samples synthesized using HPC and fired at 1050 °C under a reducing atmosphere, showed a high intensity of almost 2 times that of the MCC sample. Further experiments were conducted by varying viscosity, particle weight, and molecular weight of the HPC template. It was found that the green emission from the (Ba,Sr)SiO4:Eu2+ increased with the increase in viscosity and molecular weight of the template.

  1. Particle morphology and luminescence properties of green emitting Ba{sub 2}SiO{sub 4}:Eu{sup 2+} through a hydrothermal reaction route

    Energy Technology Data Exchange (ETDEWEB)

    Han, J.K. [Condensed Matter Physics and Materials Sciences Department, Building 480, Brookhaven National Laboratory, Upton, NY 11973 (United States); Hannah, M.E.; Piquette, A. [OSRAM SYLVANIA Central Research, 71 Cherry Hill Dr. Beverly, MA 01915 (United States); Talbot, J.B. [University of California, San Diego, Dept. of Nanoengineering, La Jolla, CA 92093 (United States); Mishra, K.C. [OSRAM SYLVANIA Central Research, 71 Cherry Hill Dr. Beverly, MA 01915 (United States); McKittrick, J., E-mail: jmckittrick@ucsd.edu [University of California, San Diego, Dept. of Mechanical and Aerospace Engineering, La Jolla, CA 92093 (United States)

    2015-05-15

    Green-emitting (Ba{sub 0.97}Eu{sub 0.03}){sub 2}SiO{sub 4} phosphors of different morphologies and particle sizes were prepared by varying the conditions of hydrothermal synthesis. Single-phase powders were obtained at 250 °C and autogeneous pressure followed by post annealing at 900 °C for 1 h. The ethanol/water ratio, hydrothermal reaction time, NaOH/Ba{sup 2+} ratio and silicon precursor strongly influence the particle size and morphology. The particle size, having spherical or needlelike shapes, ranges from 200 nm to 3 μm, depending on those parameters. These phosphors show strong absorption in the near UV range and the photoluminescence emission spectra consist of a strong broad green band centered around 514 nm. Furthermore, the emission intensities are dependent on the ethanol to water ratio, and 55–79% of that of micron-sized powders with a quantum efficiency of 94%. - Highlights: • (Ba{sub 0.97}Eu{sub 0.03}){sub 2}SiO{sub 4} with sub-micron particle sizes were prepared by hydrothermal synthesis. • Post-synthesis annealing at 900 °C results in single phase powders with a spherical morphology. • The emission intensities are 55–79% of micron-sized powders that have a quantum efficiency of 94%.

  2. Bright Fluorescence and Host-Guest Sensing with a Nanoscale M₄L₆ Tetrahedron Accessed by Self-Assembly of Zinc-Imine Chelate Vertices and Perylene Bisimide Edges.

    Science.gov (United States)

    Frischmann, Peter D; Kunz, Valentin; Würthner, Frank

    2015-06-15

    A highly luminescent Zn4L6 tetrahedron is reported with 3.8 nm perylene bisimide edges and hexadentate Zn(II)-imine chelate vertices. Replacing Fe(II) and monoamines commonly utilized in subcomponent self-assembly with Zn(II) and tris(2-aminoethyl)amine provides access to a metallosupramolecular host with the rare combination of structural integrity at concentrations <10(-7) mol L(-1) and an exceptionally high fluorescence quantum yield of Φ(em) =0.67. Encapsulation of multiple perylene or coronene guest molecules is accompanied by strong luminescence quenching. We anticipate this self-assembly strategy may be generalized to improve access to brightly fluorescent coordination cages tailored for host-guest light-harvesting, photocatalysis, and sensing.

  3. Brightness-equalized quantum dots

    Science.gov (United States)

    Lim, Sung Jun; Zahid, Mohammad U.; Le, Phuong; Ma, Liang; Entenberg, David; Harney, Allison S.; Condeelis, John; Smith, Andrew M.

    2015-10-01

    As molecular labels for cells and tissues, fluorescent probes have shaped our understanding of biological structures and processes. However, their capacity for quantitative analysis is limited because photon emission rates from multicolour fluorophores are dissimilar, unstable and often unpredictable, which obscures correlations between measured fluorescence and molecular concentration. Here we introduce a new class of light-emitting quantum dots with tunable and equalized fluorescence brightness across a broad range of colours. The key feature is independent tunability of emission wavelength, extinction coefficient and quantum yield through distinct structural domains in the nanocrystal. Precise tuning eliminates a 100-fold red-to-green brightness mismatch of size-tuned quantum dots at the ensemble and single-particle levels, which substantially improves quantitative imaging accuracy in biological tissue. We anticipate that these materials engineering principles will vastly expand the optical engineering landscape of fluorescent probes, facilitate quantitative multicolour imaging in living tissue and improve colour tuning in light-emitting devices.

  4. Synthesis and Characterization of 8-O-Carboxymethylpyranine (CM-Pyranine as a Bright, Violet-Emitting, Fluid-Phase Fluorescent Marker in Cell Biology.

    Directory of Open Access Journals (Sweden)

    Eric A Legenzov

    Full Text Available To avoid spectral interference with common fluorophores in multicolor fluorescence microscopy, a fluid-phase tracer with excitation and emission in the violet end of the visible spectrum is desirable. CM-pyranine is easily synthesized and purified. Its excitation and emission maxima at 401.5 nm and 428.5 nm, respectively, are well suited for excitation by 405-nm diode lasers now commonly available on laser-scanning microscopes. High fluorescence quantum efficiency (Q = 0.96 and strong light absorption (ε405 > 25,000 M-1cm-1 together make CM-pyranine the brightest violet aqueous tracer. The fluorescence spectrum of CM-pyranine is invariant above pH 4, which makes it a good fluid-phase marker in all cellular compartments. CM-pyranine is very photostable, is retained for long periods by cells, does not self-quench, and has negligible excimer emission. The sum of its properties make CM-pyranine an ideal fluorescent tracer. The use of CM-pyranine as a fluid-phase marker is demonstrated by multicolor confocal microscopy of cells that are also labeled with lipid and nuclear markers that have green and red fluorescence emission, respectively.

  5. Robust Colloidal Nanoparticles of Pyrrolopyrrole Cyanine J-Aggregates with Bright Near-Infrared Fluorescence in Aqueous Media: From Spectral Tailoring to Bioimaging Applications.

    Science.gov (United States)

    Yang, Cangjie; Wang, Xiaochen; Wang, Mingfeng; Xu, Keming; Xu, Chenjie

    2017-03-28

    Colloidal nanoparticles (NPs) containing near-infrared-fluorescent J-aggregates (JAGGs) of pyrrolopyrrole cyanines (PPcys) stabilized by amphiphilic block co-polymers were prepared in aqueous medium. JAGG formation can be tuned by means of the chemical structure of PPcys, the concentration of chromophores inside the polymeric NPs, and ultrasonication. The JAGG NPs exhibit a narrow emission band at 773 nm, a fluorescence quantum yield comparable to that of indocyanine green, and significantly enhanced photostability, which is ideal for long-term bioimaging.

  6. Co-precipitation synthesis and optical properties of green-emitting Ba{sub 2}MgSi{sub 2}O{sub 7}:Eu{sup 2+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Tam, T.T.H.; Du, N.V.; Kien, N.D.T.; Thang, C.X.; Cuong, N.D.; Huy, P.T. [Advanced Institute of Science and Technology (AIST), Hanoi University of Science and Technology (HUST), 01 Dai Co Viet, Hanoi (Viet Nam); Chien, N.D. [Advanced Institute of Science and Technology (AIST), Hanoi University of Science and Technology (HUST), 01 Dai Co Viet, Hanoi (Viet Nam); School of Engineering Physics (SEP), Hanoi University of Science and Technology (HUST), 01 Dai Co Viet, Hanoi (Viet Nam); Nguyen, D.H., E-mail: hung.nguyenduy@hust.edu.vn [Advanced Institute of Science and Technology (AIST), Hanoi University of Science and Technology (HUST), 01 Dai Co Viet, Hanoi (Viet Nam)

    2014-03-15

    Green-emitting Ba{sub 2−x}MgSi{sub 2}O{sub 7}:xEu{sup 2+} phosphor was prepared by co-precipitation. The dependence of the phase and emission spectra of the phosphor on sintered temperature was investigated. The photoluminescence (PL) intensities of the phosphors with various Eu{sup 2+} contents from 0.04 to 0.07 showed concentration quenching at 0.05. The substitution of Ba{sup 2+} by dopant Eu{sup 2+} at 0.05 in the Ba{sub 2}MgSi{sub 2}O{sub 7} host matrix did not change the unit cell volume and of the SiOSi angle. The PL decay times at the peak and cross band of the spectrum present carrier lifetimes with similar values at 550 ns for Ba{sub 1.95}MgSi{sub 2}O{sub 7}:0.05Eu{sup 2+} phosphor. The carrier lifetimes at different excitation wavelengths indicated that the phosphor prepared by co-precipitation is a superior candidate for fabricating white light. -- Highlights: • Green emitting Ba{sub 2−x}MgSi{sub 2}O{sub 7}:xEu{sup 2+} was prepared by co-precipitation method. • Annealing temperature affects strongly the host phase and optical properties. • Eu{sup 2+} doping into the host did not affect the cell volume and angle of SiOSi bonding. • Average size of the phosphor particles is in the range of 100–150 nm. • Ba{sub 1.95}MgSi{sub 2}O{sub 7}:Eu{sub 0.05} phosphor is an attractive candidate for white LED application.

  7. Luminescence investigation of novel MgPbAl₁₀O₁₇:Tb³⁺ green-emitting phosphor for solid-state lighting.

    Science.gov (United States)

    Panse, V R; Kokode, N S; Dhoble, S J; Yerpude, A N

    2016-05-01

    In this work, we studied the luminescence properties of Tb(3+)-doped MgPbAl10O17 green phosphor. To understand the excitation mechanism and corresponding emission of the prepared phosphor, its structural, morphological and photoluminescence properties were investigated. In general, for green emission, Tb(3) is used as an activator and the obtained excitation and emission spectra indicated that this phosphor can be effectively excited by a wavelength of 380 nm, and exhibits bright green emission centered at 545 nm corresponding to the f → f transition of trivalent terbium ions. The chromaticity coordinates were (C(x) = 0.263, C(y) = 0.723). The impact of Tb(3+) concentration on the relative emission intensity was investigated, and the best doping concentration was found to be 2 mol%. This study suggests that Tb(3+)-doped MgPbAl10O17 phosphor is a strong candidate for a green component in phosphor-converted white light-emitting diodes.

  8. 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...

  9. Luminescence and energy transfer of Mn{sup 2+} co-doped SrSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} green-emitting phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Song Xiufeng [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Yudao Street No. 29, Nanjing 210016 (China); Fu Renli [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Yudao Street No. 29, Nanjing 210016 (China)], E-mail: renlifu@nuaa.edu.cn; Agathopoulos, Simeon [Materials Science and Engineering Department, University of Ioannina, GR-451 10 Ioannina (Greece); He Hong; Zhao Xinran; Zeng Jun [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Yudao Street No. 29, Nanjing 210016 (China)

    2009-08-15

    Eu{sup 2+} and Mn{sup 2+} co-doped SrSi{sub 2}O{sub 2}N{sub 2} green-phosphors, with promising luminescent properties (examined by their powder diffuse reflection, photoluminescence excitation and emission spectra) suitable for UV converted white LEDs, were produced by high temperature solid-state reaction method. The produced materials exhibited intense broad absorption bands at 220-500 nm and a broad emission band centered at ca. 530 nm, attributed to 4f-5d transitions of Eu{sup 2+}. The emission intensity of Eu{sup 2+} ions was greatly enhanced by introducing Mn{sup 2+} ions into SrSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} due to the energy transfer from Mn{sup 2+} to Eu{sup 2+}. The energy transfer probability from Mn{sup 2+} to Eu{sup 2+} depends strongly on the Mn{sup 2+} concentration, which is maximized at a Mn{sup 2+} concentration of 3 mol%. It drastically decreases for higher concentrations. The results indicated that SrSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+}, Mn{sup 2+} is a promising green-emitting phosphor for white-light emitting diodes with near-UV LED chips.

  10. Single molecule localization microscopy of the distribution of chromatin using Hoechst and DAPI fluorescent probes

    Science.gov (United States)

    Szczurek, Aleksander T; Prakash, Kirti; Lee, Hyun-Keun; Żurek-Biesiada, Dominika J; Best, Gerrit; Hagmann, Martin; Dobrucki, Jurek W; Cremer, Christoph; Birk, Udo

    2014-01-01

    Several approaches have been described to fluorescently label and image DNA and chromatin in situ on the single-molecule level. These superresolution microscopy techniques are based on detecting optically isolated, fluorescently tagged anti-histone antibodies, fluorescently labeled DNA precursor analogs, or fluorescent dyes bound to DNA. Presently they suffer from various drawbacks such as low labeling efficiency or interference with DNA structure. In this report, we demonstrate that DNA minor groove binding dyes, such as Hoechst 33258, Hoechst 33342, and DAPI, can be effectively employed in single molecule localization microscopy (SMLM) with high optical and structural resolution. Upon illumination with low intensity 405 nm light, a small subpopulation of these molecules stochastically undergoes photoconversion from the original blue-emitting form to a green-emitting form. Using a 491 nm laser excitation, fluorescence of these green-emitting, optically isolated molecules was registered until “bleached”. This procedure facilitated substantially the optical isolation and localization of large numbers of individual dye molecules bound to DNA in situ, in nuclei of fixed mammalian cells, or in mitotic chromosomes, and enabled the reconstruction of high-quality DNA density maps. We anticipate that this approach will provide new insights into DNA replication, DNA repair, gene transcription, and other nuclear processes. PMID:25482122

  11. Single molecule localization microscopy of the distribution of chromatin using Hoechst and DAPI fluorescent probes.

    Science.gov (United States)

    Szczurek, Aleksander T; Prakash, Kirti; Lee, Hyun-Keun; Zurek-Biesiada, Dominika J; Best, Gerrit; Hagmann, Martin; Dobrucki, Jurek W; Cremer, Christoph; Birk, Udo

    2014-01-01

    Several approaches have been described to fluorescently label and image DNA and chromatin in situ on the single-molecule level. These superresolution microscopy techniques are based on detecting optically isolated, fluorescently tagged anti-histone antibodies, fluorescently labeled DNA precursor analogs, or fluorescent dyes bound to DNA. Presently they suffer from various drawbacks such as low labeling efficiency or interference with DNA structure. In this report, we demonstrate that DNA minor groove binding dyes, such as Hoechst 33258, Hoechst 33342, and DAPI, can be effectively employed in single molecule localization microscopy (SMLM) with high optical and structural resolution. Upon illumination with low intensity 405 nm light, a small subpopulation of these molecules stochastically undergoes photoconversion from the original blue-emitting form to a green-emitting form. Using a 491 nm laser excitation, fluorescence of these green-emitting, optically isolated molecules was registered until "bleached". This procedure facilitated substantially the optical isolation and localization of large numbers of individual dye molecules bound to DNA in situ, in nuclei of fixed mammalian cells, or in mitotic chromosomes, and enabled the reconstruction of high-quality DNA density maps. We anticipate that this approach will provide new insights into DNA replication, DNA repair, gene transcription, and other nuclear processes.

  12. Sunspot Bright Points

    CERN Document Server

    Choudhary, Debi Prasad

    2010-01-01

    We used the flux calibrated images through the Broad Band Filter Imager and Stokes Polarimeter data obtained with the Solar Optical Telescope onboard the Hinode spacecraft to study the properties of bright points in and around the sunspots. The well isolated bright points were selected and classified as umbral dot, peripheral umbral dot, penumbral grains and G-band bright point depending on their location. Most of the bright points are smaller than about 150 km. The larger points are mostly associated with the penumbral features. The bright points are not uniformly distributed over the umbra but preferentially located around the penumbral boundary and in the fast decaying parts of umbra. The color temperature of the bright points, derived using the continuum irradiance, are in the range of 4600 K to 6600 K with cooler ones located in the umbra. The temperature increases as a function of distance from the center to outside. The G-band, CN-band and CaII H flux of the bright points as a function of their blue ba...

  13. [Bright light therapy].

    Science.gov (United States)

    Poirrier, R; Cambron, L

    2007-01-01

    Bright light therapy is a treatment that emerged in the eighties of the last century. It can be used in different pathologies such as seasonal affective disorders, major depressions, and many disorders of the wake-sleep rhythm, whether they are of primary or secondary origin. Important progress made at the basic neuroscience levels, allows today a sound understanding of the bright light mode of action. Moreover, the main indications are now the subject of consensus reports and meta-analyses which show good levels of evidence-based medicine. Bright light therapy constitutes a first choice indication in seasonal affective disorder. It is also perfectly possible to prescribe bright light therapy in the major depression disorders. It has been demonstrated that the effect size is the same as with antidepressants of reference. It is admitted nowadays that bright light therapy may be at least, an adjunct to pharmacotherapy, in order to accelerate the antidepressant effect onset, or to prolong this effect after withdrawal of the drug. Bright light therapy can also be viewed as an alternative to the pharmacological approach especially when this one is impossible, not tolerated or not accepted by the patient. The contraindications are rare.

  14. The brightness of colour.

    Directory of Open Access Journals (Sweden)

    David Corney

    Full Text Available BACKGROUND: 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. RESULTS: 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. CONCLUSIONS: The data suggest that perceptions

  15. CA BrightStor

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CA推出的BrightStor系列存储管理解决方案已经成为企业电子商务体系架构管理战略中举足轻重的组成部分。BrightStor是一整套企业级的智能化存储管理解决方案,定位在存储硬件设备和上层应用之间,通过各种集成化的产品和工具为驻留在企业任何位置的数据提供全方位的、有效的存储管理和保护。

  16. Bright Economic Prospects

    Institute of Scientific and Technical Information of China (English)

    Zhang Minqiu

    2004-01-01

    @@ India is expected to register an 8.2% growth rate for the 2003-04 fiscal year. The overall economic situation this year has been satisfactory despite the scaled down 6-6.5% growth rate for the new fiscal year due to oil price hikes, reduced monsoon volume and some 7% inflation. Judging from the following factors, bright prospects are in store for the country down the road.

  17. Low surface brightness galaxies

    Science.gov (United States)

    Vanderhulst, J. M.; Deblok, W. J. G.; Mcgaugh, S. S.; Bothun, G. D.

    1993-01-01

    A program to investigate the properties of low surface brightness (LSB) galaxies involving surface photometry in U, B, V, R, I, and H-alpha, HI imaging with the Westerbork Synthesis Radio Telescope (WSRT) and the very large array (VLA) and spectrophotometry of H2 regions in LSB galaxies is underway. The goal is to verify the idea that LSB galaxies have low star formation rates because the local gas density falls below the critical density for star formation, and to study the stellar population and abundances in LSB galaxies. Such information should help understanding the evolutionary history of LSB galaxies. Some preliminary results are reported.

  18. How Bright Is the Sun?

    Science.gov (United States)

    Berr, Stephen

    1991-01-01

    Presents a sequence of activities designed to allow eighth grade students to deal with one of the fundamental relationships that govern energy distribution. Activities guide students to measure light bulb brightness, discover the inverse square law, compare light bulb light to candle light, and measure sun brightness. (two references) (MCO)

  19. Aftereffect of Adaptation to Illusory Brightness

    OpenAIRE

    Xinguang Cao; Hiroyuki Ito

    2011-01-01

    Several figures are known to induce illusory brightness. We tested whether adaptation to illusory brightness produced an aftereffect in brightness. After viewing a gray square area having illusory brightness (e.g., due to brightness contrast or illusory contours) for ten seconds, the illusion-inducing surround vanished. After three seconds, subjects reported whether the square area was seen as brighter than, darker than, or the same brightness as a control gray square area. The luminance of t...

  20. Control of excitation in the fluorescence microscope.

    Science.gov (United States)

    Lea, D J; Ward, D J

    1979-01-01

    In fluorescence microscopy image brightness and contrast and the rate of fading depend upon the intensity of illumination of the specimen. An iris diaphragm or neutral density filters may be used to reduce fluorescence excitation. Also the excitation bandwidth may be varied by using a broad band exciter filter with a set of interchangeable yellow glass filters at the lamphouse.

  1. Lanthanide based dual-emission fluorescent probe for detection of mercury (II) in milk.

    Science.gov (United States)

    Tan, Hongliang; Li, Qian; Ma, Chanjiao; Song, Yonghai; Xu, Fugang; Chen, Shouhui; Wang, Li

    2015-01-15

    It is highly desirable to develop a simple and sensitive method for Hg(2+) detection because of the dangerous nature of Hg(2+). In this work, we prepared a dual-emission fluorescent probe for Hg(2+) detection by combining two lanthanide chelates with different emission wavelengths. Green-emitting terbium (Tb(3+)) chelates as reference signals were embedded into SiO2 nanoparticles and red-emitting europium (Eu(3+)) chelates as response units were covalently linked to the surface of silica shell. Upon the addition of Hg(2+), the fluorescence of Eu(3+) chelates can be selectively quenched, while the fluorescence of Tb(3+) chelates remained unchanged. As a kind of Hg(2+) nanosensor, the dual-emission fluorescent probe exhibited excellent selectivity to Hg(2+) and high sensitivity up to 7.07 nM detection limit. The Hg(2+) levels in drinking water and milk samples were determined by using the dual-emission fluorescent probe with satisfied recovery. Additionally, our probe has a long enough fluorescence lifetime, which can avoid the interference from autofluorescence of the biological samples. We envision that the proposed probe could find great potential applications for ultrasensitive time-resolved fluorometric assays and biomedical imaging in the future.

  2. Fluorescence fluctuation spectroscopy (FFS), part A

    CERN Document Server

    Tetin, Sergey

    2013-01-01

    This new volume of Methods in Enzymology continues the legacy of this premier serial by containing quality chapters authored by leaders in the field. This volume covers Fluorescence Fluctuation SpectroscopyContains chapters on such topics as Time-integrated fluorescence cumulant analysis, Pulsed Interleaved Excitation, and raster image correlation spectroscopy and number and brightness analysis.Continues the legacy of this premier serial with quality chapters authored by leaders in the fieldCovers fluorescence fluctuation spectroscopyContains chapte

  3. Consecutive Bright Pulses in the Vela Pulsar

    CERN Document Server

    Palfreyman, Jim L; Dickey, John M; Young, Timothy G; Hotan, Claire E; 10.1088/2041-8205/735/1/L17

    2011-01-01

    We report on the discovery of consecutive bright radio pulses from the Vela pulsar, a new phenomenon that may lead to a greater understanding of the pulsar emission mechanism. This results from a total of 345 hr worth of observations of the Vela pulsar using the University of Tasmania's 26 m radio telescope to study the frequency and statistics of abnormally bright pulses and sub-pulses. The bright pulses show a tendency to appear consecutively. The observations found two groups of six consecutive bright pulses and many groups of two to five bright pulses in a row. The strong radio emission process that produces the six bright pulses lasts between 0.4 and 0.6 s. The numbers of bright pulses in sequence far exceed what would be expected if individual bright pulses were independent random events. Consecutive bright pulses must be generated by an emission process that is long lived relative to the rotation period of the neutron star.

  4. 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...

  5. High-brightness rf linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    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. (LEW)

  6. Fluorescent Approaches to High Throughput Crystallography

    Science.gov (United States)

    Pusey, Marc L.; Forsythe, Elizabeth; Achari, Aniruddha

    2006-01-01

    We have shown that by covalently modifying a subpopulation, less than or equal to 1%, of a macromolecule with a fluorescent probe, the labeled material will add to a growing crystal as a microheterogeneous growth unit. Labeling procedures can be readily incorporated into the final stages of purification, and the presence of the probe at low concentrations does not affect the X-ray data quality or the crystallization behavior. The presence of the trace fluorescent label gives a number of advantages when used with high throughput crystallizations. The covalently attached probe will concentrate in the crystal relative to the solution, and under fluorescent illumination crystals show up as bright objects against a dark background. Non-protein structures, such as salt crystals, will not incorporate the probe and will not show up under fluorescent illumination. Brightly fluorescent crystals are readily found against less bright precipitated phases, which under white light illumination may obscure the crystals. Automated image analysis to find crystals should be greatly facilitated, without having to first define crystallization drop boundaries as the protein or protein structures is all that shows up. Fluorescence intensity is a faster search parameter, whether visually or by automated methods, than looking for crystalline features. We are now testing the use of high fluorescence intensity regions, in the absence of clear crystalline features or "hits", as a means for determining potential lead conditions. A working hypothesis is that kinetics leading to non-structured phases may overwhelm and trap more slowly formed ordered assemblies, which subsequently show up as regions of brighter fluorescence intensity. Preliminary experiments with test proteins have resulted in the extraction of a number of crystallization conditions from screening outcomes based solely on the presence of bright fluorescent regions. Subsequent experiments will test this approach using a wider

  7. Modular generation of fluorescent phycobiliproteins.

    Science.gov (United States)

    Wu, Xian-Jun; Chang, Kun; Luo, Juan; Zhou, Ming; Scheer, Hugo; Zhao, Kai-Hong

    2013-06-01

    Phycobiliproteins are brightly-fluorescent light-harvesting pigments for photosynthesis in cyanobacteria and red algae. They are also of interest as fluorescent biomarkers, but their heterologous generation in vivo has previously required multiple transformations. We report here a modular approach that requires only two DNA segments. The first codes for the apo-protein. The second codes for fusions capable of chromophore biosynthesis and its covalent attachment to the apo-protein; it contains the genes of heme oxygenase, a bilin reductase, and a chromophore lyase. Phycobiliproteins containing phycoerythrobilin (λ(fluor) ~ 560 nm), phycourobilin (λ(fluor) ~ 500 nm), phycocyanobilin (λ(fluor) ~ 630 nm) or phycoviolobilin (λ(fluor) ~ 580 nm) were obtained in high yield in E. coli. This approach facilitates chromophorylation studies of phycobiliproteins, as well as their use for fluorescence labeling based on their high fluorescence.

  8. Fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2016-01-01

    Fluorescence spectroscopy is a powerful experimental tool used by scientists from many disciplines. During the last decades there have been important developments on distinct fluorescence methods, particularly those related to the study of biological phenomena. This chapter discusses the foundati......Fluorescence spectroscopy is a powerful experimental tool used by scientists from many disciplines. During the last decades there have been important developments on distinct fluorescence methods, particularly those related to the study of biological phenomena. This chapter discusses...

  9. How Bright Can Supernovae Get?

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    Supernovae enormous explosions associated with the end of a stars life come in a variety of types with different origins. A new study has examined how the brightest supernovae in the Universe are produced, and what limits might be set on their brightness.Ultra-Luminous ObservationsRecent observations have revealed many ultra-luminous supernovae, which haveenergies that challenge our abilities to explain them usingcurrent supernova models. An especially extreme example is the 2015 discovery of the supernova ASASSN-15lh, which shone with a peak luminosity of ~2*1045 erg/s, nearly a trillion times brighter than the Sun. ASASSN-15lh radiated a whopping ~2*1052 erg in the first four months after its detection.How could a supernova that bright be produced? To explore the answer to that question, Tuguldur Sukhbold and Stan Woosley at University of California, Santa Cruz, have examined the different sources that could produce supernovae and calculated upper limits on the potential luminosities ofeach of these supernova varieties.Explosive ModelsSukhbold and Woosley explore multiple different models for core-collapse supernova explosions, including:Prompt explosionA stars core collapses and immediately explodes.Pair instabilityElectron/positron pair production at a massive stars center leads to core collapse. For high masses, radioactivity can contribute to delayed energy output.Colliding shellsPreviously expelled shells of material around a star collide after the initial explosion, providing additional energy release.MagnetarThe collapsing star forms a magnetar a rapidly rotating neutron star with an incredibly strong magnetic field at its core, which then dumps energy into the supernova ejecta, further brightening the explosion.They then apply these models to different types of stars.Setting the LimitThe authors show that the light curve of ASASSN-15lh (plotted in orange) can be described by a model (black curve) in which a magnetar with an initial spin period of 0.7 ms

  10. VERITAS Observations under Bright Moonlight

    CERN Document Server

    ,

    2015-01-01

    The presence of moonlight is usually a limiting factor for imaging atmospheric Cherenkov telescopes due to the high sensitivity of the camera photomultiplier tubes (PMTs). In their standard configuration, the extra noise limits the sensitivity of the experiment to gamma-ray signals and the higher PMT currents also accelerates PMT aging. Since fall 2012, observations have been carried out with VERITAS under bright moonlight (Moon illumination $> 35\\%$), in two observing modes, by reducing the voltage applied to the PMTs and with UV bandpass filters, which allow observations up to $\\sim80\\%$ Moon illumination resulting in $29\\%$ more observing time over the course of the year. In this presentation, we provide details of these new observing modes and their performance relative to the standard VERITAS observations.

  11. Aftereffect of Adaptation to Illusory Brightness

    Directory of Open Access Journals (Sweden)

    Xinguang Cao

    2011-05-01

    Full Text Available Several figures are known to induce illusory brightness. We tested whether adaptation to illusory brightness produced an aftereffect in brightness. After viewing a gray square area having illusory brightness (e.g., due to brightness contrast or illusory contours for ten seconds, the illusion-inducing surround vanished. After three seconds, subjects reported whether the square area was seen as brighter than, darker than, or the same brightness as a control gray square area. The luminance of the tested square area was physically unchanged. The results show that when the black surround inducing brightness contrast suddenly became gray (i.e., vanished, the center gray square tended to look darker than a control gray square. Similarly, after viewing a subjective square consisting of black-line terminations, the square area tended to look darker than the control even though the afterimage of the lines could not be seen. These results indicate that induced or illusory brightness causes an aftereffect in brightness regardless of the appearance of negative afterimages of the illusion-inducing components.

  12. 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.

  13. Bright Star Astrometry with URAT

    CERN Document Server

    Zacharias, Norbert

    2015-01-01

    The U.S. Naval Observatory Robotic Astrometric Telescope (URAT) is observing the northern sky since April 2012 for an astrometric survey. Multiple overlaps per year are performed in a single bandpass (680$-$750 nm) using the "redlens" 20 cm aperture astrograph and a mosaic of large CCDs. Besides the regular, deep survey to magnitude 18.5, short exposures with an objective grating are taken to access stars as bright as 3rd magnitude. A brief overview of the program, observing and reductions is given. Positions on the 8 to 20 mas level are obtained of 66,202 Hipparcos stars at current epochs. These are compared to the Hipparcos Catalog to investigate its accuracy. About 20\\% of the observed Hipparcos stars are found to have inconsitent positions with the Hipparcos Catalog prediction on the 3 sigma level or over (about 75 mas or more discrepant position offsets). Some stars are now seen at an arcsec (or 25 sigma) off their Hipparcos Catalog predicted position.

  14. 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

  15. 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. Th

  16. Galaxy selection and the surface brightness distribution

    CERN Document Server

    McGaugh, S S; Schombert, J M

    1995-01-01

    Optical surveys for galaxies are biased against the inclusion of low surface brightness (LSB) galaxies. Disney (1976) suggested that the constancy of disk central surface brightness noticed by Freeman (1970) was not a physical result, but instead was an artifact of sample selection. Since LSB galaxies do exist, the pertinent and still controversial issue is if these newly discovered galaxies constitute a significant percentage of the general galaxy population. In this paper, we address this issue by determining the space density of galaxies as a function of disk central surface brightness. Using the physically reasonable assumption (which is motivated by the data) that central surface brightness is independent of disk scale length, we arrive at a distribution which is roughly flat (\\ie approximately equal numbers of galaxies at each surface brightness) faintwards of the Freeman (1970) value. Brightwards of this, we find a sharp decline in the distribution which is analogous to the turn down in the luminosity ...

  17. Bright Streaks and Dark Fans

    Science.gov (United States)

    2007-01-01

    The south polar region of Mars is covered every year by a layer of carbon dioxide ice. In a region called the 'cryptic terrain,' the ice is translucent and sunlight can penetrate through the ice to warm the surface below. The ice layer sublimates (evaporates) from the bottom. The dark fans of dust seen in this image come from the surface below the layer of ice, carried to the top by gas venting from below. The translucent ice is 'visible' by virtue of the effect it has on the tone of the surface below, which would otherwise have the same color and reflectivity as the fans. Bright streaks in this image are fresh frost. The CRISM team has identified the composition of these streaks to be carbon dioxide. Observation Geometry Image PSP_003113_0940 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 26-Mar-2007. The complete image is centered at -85.8 degrees latitude, 106.0 degrees East longitude. The range to the target site was 244.9 km (153.0 miles). At this distance the image scale is 49.0 cm/pixel (with 2 x 2 binning) so objects 147 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 06:20 PM and the scene is illuminated from the west with a solar incidence angle of 79 degrees, thus the sun was about 11 degrees above the horizon. At a solar longitude of 207.6 degrees, the season on Mars is Northern Autumn.

  18. 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.

  19. Space Brightness Evaluation for a Daylit Room

    Directory of Open Access Journals (Sweden)

    Takashi Maruyama

    2011-05-01

    Full Text Available One of the most important problems for lighting design is how to reduce an electric energy. One way to solve this problem is use of daylight, but little is known how to perceive a brightness of a room illuminated by daylight come in through a window and artificial light. Although the horizontal illuminance increases because of daylight, we would not perceive the room as bright as brightness estimated by the illuminance. The purpose of this study is to measure the space brightness for daylit room and to propose a evaluation method. The experiment was conducted with a couple of miniature office rooms, standard room and test room. Test room has several types of windows and standard room has no window. Subject was asked to evaluate the brightness of the test room relative to the standard room with method of magnitude estimation. It was found that brightness of daylit room did not increase simply with horizontal illuminance. Subject perceived a daylit room darker than a room illuminated only by the artificial light even if horizontal illuminance of these room was same. The effect of daylight on space brightness would vary with the window size and intensity of daylight or artificial light.

  20. 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

  1. Brightness of synchrotron radiation from wigglers

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2014-01-01

    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. I...

  2. The analogy between stereo depth and brightness.

    Science.gov (United States)

    Brookes, A; Stevens, K A

    1989-01-01

    Apparent depth in stereograms exhibits various simultaneous-contrast and induction effects analogous to those reported in the luminance domain. This behavior suggests that stereo depth, like brightness, is reconstructed, ie recovered from higher-order spatial derivatives or differences of the original signal. The extent to which depth is analogous to brightness is examined. There are similarities in terms of contrast effects but dissimilarities in terms of the lateral inhibition effects traditionally attributed to underlying spatial-differentiation operators.

  3. Observations and diagnostics in high brightness beams

    Energy Technology Data Exchange (ETDEWEB)

    Cianchi, A., E-mail: alessandro.cianchi@roma2.infn.it [University of Rome Tor Vergata and INFN-Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome (Italy); Anania, M.P.; Bisesto, F.; Castellano, M.; Chiadroni, E.; Pompili, R.; Shpakov, V. [INFN-LNF, Via Enrico Fermi 40, 00044 Frascati (Italy)

    2016-09-01

    The brightness is a figure of merit largely used in the light sources, like FEL (Free Electron Lasers), but it is also fundamental in several other applications, as for instance Compton backscattering sources, beam driven plasma accelerators and THz sources. Advanced diagnostics are essential tools in the development of high brightness beams. 6D electron beam diagnostics will be reviewed with emphasis on emittance measurement.

  4. A Bright Single Photon Source Based on a Diamond Nanowire

    CERN Document Server

    Babinec, T; Khan, M; Zhang, Y; Maze, J; Hemmer, P R; Loncar, M

    2009-01-01

    The development of a robust light source that emits one photon at a time is an outstanding challenge in quantum science and technology. Here, at the transition from many to single photon optical communication systems, fully quantum mechanical effects may be utilized to achieve new capabilities, most notably perfectly secure communication via quantum cryptography. Practical implementations place stringent requirements on the device properties, including fast and stable photon generation, efficient collection of photons, and room temperature operation. Single photon light emitting devices based on fluorescent dye molecules, quantum dots, nanowires, and carbon nanotube material systems have all been explored, but none have simultaneously demonstrated all criteria. Here, we describe the design, fabrication, and characterization of a bright source of single photons consisting of an individual Nitrogen-vacancy color center (NV center) in a diamond nanowire operating in ambient conditions. The nanowire plays a posit...

  5. Fluorescence-Based Sensors

    Science.gov (United States)

    Orellana, Guillermo

    The natural luminescent phenomena (from the Latin words "lumen" and "essentia", i.e., "made of light") such as northern lights (aurora borealis), marine brightness, glow-worms, shining putrid fish scales, "bluish"- appearing water when contained in certain wooden cups (quinine fluorescence), some stones heated at high temperatures with reducing agents (BaS phosphorescence), or light emitted while crushing sugar (triboluminescence) already fascinated our ancestors. Nowadays we understand that ultraviolet and visible emission of light originates from a competitive deactivation pathway of the lowest electronic excited state of atoms and molecules that produces the so called luminescence (the sub-terms fluorescence and phosphorescence just designate whether the return of the excited to the ground state is an "allowed" or "forbidden" process, namely it is fast or slow, the loosely-defined border between them being a 1-μs-1 rate constant). Actually, luminescence is the only method to generate light in the known Universe regardless it is powered by the nuclear reactions in the stars, the ohmical heating in bulbs, an electric discharge, the absorption of light or a (bio)chemical reaction (chemiluminescence).

  6. A highly selective ratiometric fluorescent pH probe based on a PAMAM wavelength-shifting bichromophoric system

    Science.gov (United States)

    Alamry, Khalid A.; Georgiev, Nikolai I.; El-Daly, Samy Abdullah; Taib, Layla A.; Bojinov, Vladimir B.

    2015-01-01

    A novel PAMAM wavelength-shifting bichromophoric system has been successfully developed. Novel compound was configured as a light harvesting antenna where the system surface is labeled with yellow-green emitting 4-(N,N-dimethylamino)ethylamino-1,8-naphthalimide "donor" units capable of absorbing light and efficiently transferring the energy to a focal Rhodamine 6G "acceptor". The periphery of the system was designed on the "fluorophore-spacer-receptor" format, capable of acting as a molecular fluorescence photoinduced electron transfer based probe. Due to the both effects, photoinduced electron transfer in the periphery of the system and pH dependent rhodamine core absorption, novel antenna is able to act as a selective ratiometric pH fluorescence probe in aqueous medium. Thus, the distinguishing features of the fluorescence resonance energy transfer systems were successfully combined with the properties of classical ring-opening charge transfer systems, which may be beneficially for monitoring pH variations in complex samples.

  7. Bright stars observed by FIMS/SPEAR

    CERN Document Server

    Jo, Young-Soo; Min, Kyoung-Wook; Choi, Yeon-Ju; Lim, Tae-Ho; Lim, Yeo-Myeong; Edelstein, Jerry; Han, Wonyong

    2015-01-01

    In this paper, we present a catalogue of the spectra of bright stars observed during the sky survey using the Far-Ultraviolet Imaging Spectrograph (FIMS), which was designed primarily to observe diffuse emissions. By carefully eliminating the contamination from the diffuse background, we obtain the spectra of 70 bright stars observed for the first time with a spectral resolution of 2--3 {\\AA} over the wavelength of 1370--1710 {\\AA}. The far-ultraviolet spectra of an additional 139 stars are also extracted with a better spectral resolution and/or higher reliability than those of the previous observations. The stellar spectral type of the stars presented in the catalogue spans from O9 to A3. The method of spectral extraction of the bright stars is validated by comparing the spectra of 323 stars with those of the International Ultraviolet Explorer (IUE) observations.

  8. Brightness discrimination in budgerigars (Melopsittacus undulatus.

    Directory of Open Access Journals (Sweden)

    Olle Lind

    Full Text Available Birds have excellent spatial acuity and colour vision compared to other vertebrates while spatial contrast sensitivity is relatively poor for unknown reasons. Contrast sensitivity describes the detection of gratings of varying spatial frequency. It is unclear whether bird brightness discrimination between large uniform fields is poor as well. Here we show that budgerigars (Melopsittacus undulatus need a Michelson contrast of 0.09 to discriminate between large spatially separated achromatic fields in bright light conditions. This is similar to the peak contrast sensitivity of 10.2 (0.098 Michelson contrast for achromatic grating stimuli established in earlier studies. The brightness discrimination threshold described in Weber fractions is 0.18, which is modest compared to other vertebrates.

  9. 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

  10. The historical investigation of cometary brightness

    Science.gov (United States)

    Hughes, David W.

    1998-12-01

    The interpretation of the way in which the brightness of a comet varied as a function of both its heliocentric and geocentric distance was essentially started by Isaac Newton in his book Philosophiae Naturalis Principia Mathematica, published in 1687. Astronomers have argued about the form of this variability ever since, and for many years it was regarded as an important clue as to the physical nature of the cometary nucleus and its decay process. This paper reviews our understanding of the causes of cometary brightness variability between about 1680 and the 1950s.

  11. Fluorescent nanoparticles based on AIE fluorogens for bioimaging

    Science.gov (United States)

    Yan, Lulin; Zhang, Yan; Xu, Bin; Tian, Wenjing

    2016-01-01

    Fluorescent nanoparticles (FNPs) have recently attracted increasing attention in the biomedical field because of their unique optical properties, easy fabrication and outstanding performance in imaging. Compared with conventional molecular probes including small organic dyes and fluorescent proteins, FNPs based on aggregation-induced emission (AIE) fluorogens have shown significant advantages in tunable emission and brightness, good biocompatibility, superb photo- and physical stability, potential biodegradability and facile surface functionalization. In this review, we summarize the latest advances in the development of fluorescent nanoparticles based on AIE fluorogens including polymer nanoparticles and silica nanoparticles over the past few years, and the various biomedical applications based on these fluorescent nanoparticles are also elaborated.

  12. Fluorescent microspheres

    Science.gov (United States)

    Rembaum, A.

    1978-01-01

    Latex particles with attached antibodies have potential biochemical and environmental applications. Human red blood cells and lymphocytes have been labeled with fluorescent microspheres by either direct or indirect immunological technique. Immunolatex spheres can also be used for detecting and localizing specific cell surface receptors. Hormones and toxins may also be bondable.

  13. Systematic investigation of the influence of CdTe QDs size on the toxic interaction with human serum albumin by fluorescence quenching method

    Science.gov (United States)

    Xiao, Jianbo; Bai, Yalong; Wang, Yuanfeng; Chen, Jingwen; Wei, Xinlin

    2010-06-01

    Quantum dots (QDs) are complementary tools to the organic fluorescent dyes used in biological system. Investigation of QDs biological toxicity has attracted great interest for their depth application. Here, the fluorescence quenching method was used to investigate the influence of CdTe QDs size on the toxic interaction with human serum albumin (HSA). Two aqueous-compatible CdTe QDs with maximum emission of 535 nm (green-emitting QDs, G-QDs, 2.04 nm) and 654 nm (red-emitting QDs, R-QDs, 3.79 nm) were tested. The fluorescence quenching results indicated that the quenching effect of QDs on HSA fluorescence depended on the size and the nature of quenching is not dynamic but probably static, resulting in forming QDs-HSA complexes. The binding constants and the number of binding sites between R-QDs and HSA were higher than those of G-QDs. The results illustrated that the size of CdTe quantum dots affected the affinity for HSA and the increasing size of QDs enhanced the affinity for HSA. The values of lg Ka are proportional to the number of binding sites ( n). This result confirms the method used here is suitable to study the toxic interaction between QDs and HSA.

  14. Fluorescence enhancement of photoswitchable metal ion sensors

    Science.gov (United States)

    Sylvia, Georgina; Heng, Sabrina; Abell, Andrew D.

    2016-12-01

    Spiropyran-based fluorescence sensors are an ideal target for intracellular metal ion sensing, due to their biocompatibility, red emission frequency and photo-controlled reversible analyte binding for continuous signal monitoring. However, increasing the brightness of spiropyran-based sensors would extend their sensing capability for live-cell imaging. In this work we look to enhance the fluorescence of spiropyran-based sensors, by incorporating an additional fluorophore into the sensor design. We report a 5-membered monoazacrown bearing spiropyran with metal ion specificity, modified to incorporate the pyrene fluorophore. The effect of N-indole pyrene modification on the behavior of the spiropyran molecule is explored, with absorbance and fluorescence emission characterization. This first generation sensor provides an insight into fluorescence-enhancement of spiropyran molecules.

  15. Protein-Sized Bright Fluorogenic Nanoparticles Based on Cross-Linked Calixarene Micelles with Cyanine Corona.

    Science.gov (United States)

    Shulov, Ievgen; Rodik, Roman V; Arntz, Youri; Reisch, Andreas; Kalchenko, Vitaly I; Klymchenko, Andrey S

    2016-12-19

    The key challenge in the field of fluorescent nanoparticles (NPs) for biological applications is to achieve superior brightness for sizes equivalent to single proteins (3-7 nm). We propose a concept of shell-cross-linked fluorescent micelles, in which PEGylated cyanine 3 and 5 bis-azides form a covalently attached corona on micelles of amphiphilic calixarene bearing four alkyne groups. The fluorescence quantum yield of the obtained monodisperse NPs, with a size of 7 nm, is a function of viscosity and reached up to 15 % in glycerol. In the on-state they are circa 2-fold brighter than quantum dots (QD-585), which makes them the smallest PEGylated organic NPs of this high brightness. FRET between cyanine 3 and 5 cross-linkers at the surface of NPs suggests their integrity in physiological media, organic solvents, and living cells, in which the NPs rapidly internalize, showing excellent imaging contrast. Calixarene micelles with a cyanine corona constitute a new platform for the development of protein-sized ultrabright fluorescent NPs.

  16. Brightness of synchrotron radiation from wigglers

    Science.gov (United States)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2016-01-01

    According to the 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. We exemplify this formalism in simple limiting cases. 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 the literature.

  17. Bright Future for Petroleum Development Cooperation

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhenqing

    1996-01-01

    @@ China's oil prospects look bright, since reform and opening speed up. The oil production of 1995 is 148 million tons and the confirmed reserves of oil and gas only occupy one-fifth of those possible to be verified, the petroleum exploration will be deepened to locate and confirm the remaining reserves.

  18. Dark Matter in Low Surface Brightness Galaxies

    NARCIS (Netherlands)

    Blok, W. J. G. de; McGaugh, S. S.

    1996-01-01

    Abstract: Low Surface Brightness (LSB) galaxies form a large population of disc galaxies that extend the Hubble sequence towards extreme late-types. They are only slowly evolving, and still in an early evolutionary state. The Tully-Fisher relation and rotation curves of LSB galaxies both show that L

  19. Dark matter in low surface brightness galaxies

    NARCIS (Netherlands)

    de Blok, WJG; McGaugh, SS; Persic, M; Salucci, P

    1997-01-01

    Low Surface Brightness (LSB) galaxies form a large population of disc galaxies that extend the Hubble sequence towards extreme late-types. They are only slowly evolving, and still in an early evolutionary state. The Tully-Fisher relation and rotation curves of LSB galaxies both show that LSB galaxie

  20. A photometric investigation of a bright Geminid

    NARCIS (Netherlands)

    Degewij, J.; Diggelen, Johannes van

    1968-01-01

    Photographic observations of meteors in the Netherlands started with a bright Geminid of photographic magnitude −8 observed on December 11, 1955, 21h39m55s by M. Alberts. From the assumed radiant and velocity we have constructed the trajectory of the bolide. The luminosity of the trail has been dete

  1. Alberta Associations for Bright Children Members' Handbook.

    Science.gov (United States)

    Alberta Association for Bright Children, Edmonton.

    This handbook is designed to provide information to parents of gifted children in Alberta, Canada. The handbook outlines the mission and objectives of the Alberta Associations for Bright Children and describes the structure of the non-profit organization. The booklet then addresses: (1) the characteristics of gifted children; (2) the rights of…

  2. Brightness and darkness as perceptual dimensions.

    Directory of Open Access Journals (Sweden)

    Tony Vladusich

    2007-10-01

    Full Text Available 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 results of many previous psychophysical studies suggest, by contrast, that achromatic colors are represented as points in a color space composed of two or more perceptual dimensions. The nature of these perceptual dimensions, however, presently remains unclear. Here we provide direct evidence that brightness and darkness form the dimensions of a two-dimensional (2-D achromatic color space. This color space may play a role in the representation of object surfaces viewed against natural backgrounds, which simultaneously induce both brightness and darkness signals. Our 2-D model generalizes to the chromatic dimensions of color perception, indicating that redness and greenness (blueness and yellowness also form perceptual dimensions. Collectively, these findings suggest that human color space is composed of six dimensions, rather than the conventional three.

  3. Probable Bright Supernova discovered by PSST

    Science.gov (United States)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-09-01

    A bright transient, which is a probable supernova, has been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  4. Use of astronomy filters in fluorescence microscopy.

    Science.gov (United States)

    Piper, Jörg

    2012-02-01

    Monochrome astronomy filters are well suited for use as excitation or suppression filters in fluorescence microscopy. Because of their particular optical design, such filters can be combined with standard halogen light sources for excitation in many fluorescent probes. In this "low energy excitation," photobleaching (fading) or other irritations of native specimens are avoided. Photomicrographs can be taken from living motile fluorescent specimens also with a flash so that fluorescence images can be created free from indistinctness caused by movement. Special filter cubes or dichroic mirrors are not needed for our method. By use of suitable astronomy filters, fluorescence microscopy can be carried out with standard laboratory microscopes equipped with condensers for bright-field (BF) and dark-field (DF) illumination in transmitted light. In BF excitation, the background brightness can be modulated in tiny steps up to dark or black. Moreover, standard industry microscopes fitted with a vertical illuminator for examinations of opaque probes in DF or BF illumination based on incident light (wafer inspections, for instance) can also be used for excitation in epi-illumination when adequate astronomy filters are inserted as excitatory and suppression filters in the illuminating and imaging light path. In all variants, transmission bands can be modulated by transmission shift.

  5. Synthesis and fluorescent properties of poly(arylpyrazoline)'s for organic-electronics

    Science.gov (United States)

    Vandana, T.; Ramkumar, V.; Kannan, P.

    2016-08-01

    The present work focuses on the synthesis and characterization of poly(arylchalcone)'s (PCH I-IV) by reacting acetone with various dialdehydes for the first time at below ambient temperature followed by cyclization with phenylhydrazinehydrochloride to yield luminescent poly(arylpyrazoline)'s (PPY I-IV). The synthesized polymers were characterized by standard techniques such as, GPC, SEM, TGA, FT-IR, 1H NMR, UV-Vis absorption and fluorescence spectroscopy, and electrochemical studies by cyclic voltammetry analyses. The Pyrazoline group hooked with different aryl donors such as benzene, thiophene, carbazole, triphenylamine, thus results a series of blue and green emitting materials. The obtained optical bandgap energy of the polymers (PPY I-IV) were 2.53, 3.41, 3.07, 3.10 eV respectively, suggest that all the polymers belongs to semiconducting category. The solvent effect of polymers was thoroughly studied and explained by Lippert-Mataga equation. The polymers I & IV display large degree of intra-molecular charge transfer in excited state evidenced from solvatochromic shift on the emission spectra. The obtained results demonstrate that they are promising materials for organic electronics applications.

  6. Fluorescent polystyrene photonic crystals self-assembled with water-soluble conjugated polyrotaxanes

    Directory of Open Access Journals (Sweden)

    Francesco Di Stasio

    2013-10-01

    Full Text Available We demonstrate control of the photoluminescence spectra and decay rates of water-soluble green-emitting conjugated polyrotaxanes by incorporating them in polystyrene opals with a stop-band spectrally tuned on the rotaxane emission (405–650 nm. We observe a suppression of the luminescence within the photonic stop-band and a corresponding enhancement of the high-energy edge (405–447 nm. Time-resolved measurements reveal a wavelength-dependent modification of the emission lifetime, which is shortened at the high-energy edge (by ∼11%, in the range 405–447 nm, but elongated within the stop-band (by ∼13%, in the range 448–482 nm. We assign both effects to the modification of the density of photonic states induced by the photonic crystal band structure. We propose the growth of fluorescent composite photonic crystals from blends of “solvent-compatible” non-covalently bonded nanosphere-polymer systems as a general method for achieving a uniform distribution of polymeric dopants in three-dimensional self-assembling photonic structures.

  7. The bright optical flash from GRB 060117

    CERN Document Server

    Jel'inek, M; Kubánek, P; Hudec, R; Nekola, M; Grygar, J; Castro-Tirado, A J; Gorosabel, J; Hrabovsk'y, M; Mandat, D; Nosek, D; Palatka, M; Pandey, S B; Pech, M; Schovanek, P; De Postigo, A U; Vítek, S; Jel\\'inek, Martin; Prouza, Michael; Kub\\'anek, Petr; Hudec, Ren\\'e; Nekola, Martin; R}\\'idk\\'y, Jan {; Grygar, Ji{r}\\'i; Castro-Tirado, Alberto J.; Gorosabel, Javier; Hrabovsk\\'y, Miroslav; Mand\\'at, Du{s}an; Nosek, Dalibor; Palatka, Miroslav; Pandey, Shashi B.; Pech, Miroslav; Schov\\'anek, Petr; S}m\\'ida, Radom\\'ir {; Postigo, Antonio de Ugarte; V\\'itek, Stanislav

    2006-01-01

    We present a discovery and observation of an extraordinarily bright prompt optical emission of the GRB 060117 obtained by a wide-field camera atop the robotic telescope FRAM of the Pierre Auger Observatory from 2 to 10 minutes after the GRB. We found rapid average temporal flux decay of alpha = -1.7 +- 0.1 and a peak brightness R = 10.1 mag. Later observations by other instruments set a strong limit on the optical and radio transient fluxes, unveiling an unexpectedly rapid further decay. We present an interpretation featuring a relatively steep electron-distribution parameter p ~ 3.0 and providing a straightforward solution for the overall fast decay of this optical transient as a transition between reverse and forward shock.

  8. Emittance measurement of high-brightness microbeams

    Energy Technology Data Exchange (ETDEWEB)

    Ishizuka, Hiroshi; Nakahara, Yuriko (Fukuoka Inst. of Tech. (Japan)); Kawasaki, Sunao; Musyoki, S.; Shimizu, Hiroshi; Watanabe, Akihiko; Shiho, Makoto

    1994-09-01

    Arrays of microtriodes have recently become available due to the development of microfabricated field-emission electron sources. Computer simulation has shown that the brightness of beams emitted by them is significantly higher than that of the common microbeams, and possible application of the accelerated beam to free electron lasers has been discussed. Experimentation on beam generation has started, but methods for diagnosing the beam have not yet been established. Difficulty is predicted, because of the high brightness, in applying the conventional methods of emittance measurement. In this paper we propose a new method that determines the emittance without using apertures. The cross section of a converging beam is elongated by a quadrupole lens, and parameters of the emittance ellipse are obtained from the beam size on a screen when changing either the strength or the axial position of the quadrupole lens. (author).

  9. 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.

  10. 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.

  11. On the origin of facular brightness

    CERN Document Server

    Kostik, R

    2016-01-01

    This paper studies the dependence of the CaIIH line core brightness on the strength and inclination of photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the solar disc center. We use three simultaneous datasets obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of BaII 4554 A line registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in FeI 1.56 $\\mu$m lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in CaIIH that give information about brightness fluctuations in the chromosphere. The results show that the CaIIH brightness in the facula strongly depends on the power of waves with periods in the 5-min range, that propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature min...

  12. The Bright SHARC Survey The Cluster Catalog

    CERN Document Server

    Romer, A K; Holden, B P; Ulmer, M P; Pildis, R A; Merrelli, A J; Adami, C; Burke, D J; Collins, C A; Metevier, A J; Kron, Richard G; Commons, K

    1999-01-01

    We present the Bright SHARC (Serendipitous High-Redshift Archival ROSAT Cluster) Survey, which is an objective search for serendipitously detected extended X-ray sources in 460 deep ROSAT PSPC pointings. The Bright SHARC Survey covers an area of 178.6 sq.deg and has yielded 374 extended sources. We discuss the X-ray data reduction, the candidate selection and present results from our on-going optical follow-up campaign. The optical follow-up concentrates on the brightest 94 of the 374 extended sources and is now 97% complete. We have identified thirty-seven clusters of galaxies, for which we present redshifts and luminosities. The clusters span a redshift range of 0.0696Bright SHARC clusters have not been listed in any previously ...

  13. Brightness illusion in the guppy (Poecilia reticulata).

    Science.gov (United States)

    Agrillo, Christian; Miletto Petrazzini, Maria Elena; Bisazza, Angelo

    2016-02-01

    A long-standing debate surrounds the issue of whether human and nonhuman species share similar perceptual mechanisms. One experimental strategy to compare visual perception of vertebrates consists in assessing how animals react in the presence of visual illusions. To date, this methodological approach has been widely used with mammals and birds, while few studies have been reported in distantly related species, such as fish. In the present study we investigated whether fish perceive the brightness illusion, a well-known illusion occurring when 2 objects, identical in physical features, appear to be different in brightness. Twelve guppies (Poecilia reticulata) were initially trained to discriminate which rectangle was darker or lighter between 2 otherwise identical rectangles. Three different conditions were set up: neutral condition between rectangle and background (same background used for both darker and lighter rectangle); congruent condition (darker rectangle in a darker background and lighter rectangle in a lighter background); and incongruent condition (darker rectangle in a lighter background and lighter rectangle in a darker background). After reaching the learning criterion, guppies were presented with the illusory pattern: 2 identical rectangles inserted in 2 different backgrounds. Guppies previously trained to select the darker rectangle showed a significant choice of the rectangle that appears to be darker by human observers (and vice versa). The human-like performance exhibited in the presence of the illusory pattern suggests the existence of similar perceptual mechanisms between humans and fish to elaborate the brightness of objects.

  14. Cooperative effects and slow dynamics of fluorescence intensity from quantum emitters in a dielectric

    Science.gov (United States)

    Lozing, N. A.; Gladush, M. G.

    2016-12-01

    We study theoretically the possibility of spontaneous switching between dim and bright fluorescence modes from a cooperative ensemble of two-level atoms driven by a cw-laser. A numerical analysis of transient regimes and transformations of the fluorescence spectrum are reported.

  15. Facile consecutive solvothermal growth of highly fluorescent InP/ZnS core/shell quantum dots using a safer phosphorus source.

    Science.gov (United States)

    Byun, Ho-June; Song, Woo-Seuk; Yang, Heesun

    2011-06-10

    The work presents a facile, stepwise synthetic approach for the production of highly fluorescent InP/ZnS core/shell quantum dots (QDs) by using a safer phosphorus (P) precursor. First, InP quantum dots (QDs) were solvothermally prepared at 180 °C for 24 h by using a P source of P(N(CH(3))(2))(3). The as-grown InP QDs were consecutively placed in another solvothermal condition for ZnS shell overcoating. In contrast to the almost non-fluorescent InP QDs, due to their highly defective surface states, the ZnS-coated InP QDs were highly fluorescent as a result of effective surface passivation. After the shell growth, the resulting InP/ZnS core/shell QDs were subjected to a size-sorting processing, by which red- to green-emitting QDs with quantum yields (QYs) of 24-60% were produced. Solvothermal shell growth parameters such as the reaction time and Zn/In solution concentration ratio were varied and optimized toward the highest QYs of core/shell QDs.

  16. Bright-field Nanoscopy: Visualizing Nano-structures with Localized Optical Contrast Using a Conventional Microscope

    CERN Document Server

    Suran, Swathi; Raghavan, Srinivasan; Varma, Manoj M

    2015-01-01

    Most methods for optical visualization beyond the diffraction limit rely on fluorescence emission by molecular tags. Here, we report a method for visualization of nanostructures down to a few nanometers using a conventional bright-field microscope without requiring additional molecular tags such as fluorophores. The technique, Bright-field Nanoscopy, is based on the strong thickness dependent color of ultra-thin germanium on an optically thick gold film. We demonstrate the visualization of grain boundaries in chemical vapour deposited single layer graphene and the detection of single 40 nm Ag nanoparticles. We estimate a size detection limit of about 2 nm using this technique. In addition to visualizing nano-structures, this technique can be used to probe fluid phenomena at the nanoscale, such as transport through 2D membranes. We estimated the water transport rate through a 1 nm thick polymer film using this technique, as an illustration. Further, the technique can also be extended to study the transport of ...

  17. Estimation of the space density of low surface brightness galaxies

    NARCIS (Netherlands)

    Briggs, FH

    1997-01-01

    The space density of low surface brightness and tiny gas-rich dwarf galaxies are estimated for two recent catalogs: the Arecibo Survey of Northern Dwarf and Low Surface Brightness Galaxies and the Catalog of Low Surface Brightness Galaxies, List II. The goals are (1) to evaluate the additions to the

  18. Fluorescent probe based on heteroatom containing styrylcyanine: pH-sensitive properties and bioimaging in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaodong [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China); Gao, Ya; Huang, Zhibing; Chen, Xiaohui; Ke, Zhiyong [School of Basic Medical Science, Southern Medical University, Guangzhou 510515 (China); Zhao, Peiliang; Yan, Yichen [Department of Organic Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515 (China); Liu, Ruiyuan, E-mail: ruiyliu@smu.edu.cn [Department of Organic Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515 (China); Qu, Jinqing, E-mail: cejqqu@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China)

    2015-07-01

    A novel fluorescent probe based on heteroatom containing styrylcyanine is synthesized. The fluorescence of probe is bright green in basic and neutral media but dark orange in strong acidic environments, which could be reversibly switched. Such behavior enables it to work as a fluorescent pH sensor in the solution state and a chemosensor for detecting acidic and basic volatile organic compounds. Analyses by NMR spectroscopy confirm that the protonation or deprotonation of pyridinyl moiety is responsible for the sensing process. In addition, the fluorescent microscopic images of probe in live cells and zebrafish are achieved successfully, suggesting that the probe has good cell membrane permeability and low cytotoxicity. - Graphical abstract: A novel styrylcyanine-based fluorescent pH probe was designed and synthesized, the fluorescence of which is bright green in basic and neutral media but dark orange in strong acidic environments. Such behavior enables it to work as a fluorescent pH sensor in solution states, and a chemosensor for detecting volatile organic compounds with high acidity and basicity in solid state. In addition, it can be used for fluorescent imaging in living cell and living organism. - Highlights: • Bright green fluorescence was observed in basic and neutral media. • Dark orange fluorescence was found in strong acidic environments. • Volatile organic compounds with high acidity and basicity could be detected. • Bioimaging in living cell and living organism was achieved successfully.

  19. 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

  20. Toward structurally defined carbon dots as ultracompact fluorescent probes.

    Science.gov (United States)

    LeCroy, Gregory Ethan; Sonkar, Sumit Kumar; Yang, Fan; Veca, L Monica; Wang, Ping; Tackett, Kenneth N; Yu, Jing-Jiang; Vasile, Eugeniu; Qian, Haijun; Liu, Yamin; Luo, Pengju George; Sun, Ya-Ping

    2014-05-27

    There has been much discussion on the need to develop fluorescent quantum dots (QDs) as ultracompact probes, with overall size profiles comparable to those of the genetically encoded fluorescent tags. In the use of conventional semiconductor QDs for such a purpose, the beautifully displayed dependence of fluorescence color on the particle diameter becomes a limitation. More recently, carbon dots have emerged as a new platform of QD-like fluorescent nanomaterials. The optical absorption and fluorescence emissions in carbon dots are not bandgap in origin, different from those in conventional semiconductor QDs. The absence of any theoretically defined fluorescence color-dot size relationships in carbon dots may actually be exploited as a unique advantage in the size reduction toward having carbon dots serve as ultracompact QD-like fluorescence probes. Here we report on carbon dots of less than 5 nm in the overall dot diameter with the use of 2,2'-(ethylenedioxy)bis(ethylamine) (EDA) molecules for the carbon particle surface passivation. The EDA-carbon dots were found to be brightly fluorescent, especially over the spectral range of green fluorescent protein. These aqueous soluble smaller carbon dots also enabled more quantitative characterizations, including the use of solution-phase NMR techniques, and the results suggested that the dot structures were relatively simple and better-defined. The potential for these smaller carbon dots to serve as fluorescence probes of overall sizes comparable to those of fluorescent proteins is discussed.

  1. Quantification of DNA repair protein kinetics after γ-irradiation using number and brightness analysis

    Science.gov (United States)

    Abdisalaam, Salim; Poudel, Milan; Chen, David J.; Alexandrakis, George

    2011-03-01

    The kinetics of most proteins involved in DNA damage sensing, signaling and repair following ionizing radiation exposure cannot be quantified by current live cell fluorescence microscopy methods. This is because most of these proteins, with only few notable exceptions, do not attach in large numbers at DNA damage sites to form easily detectable foci in microscopy images. As a result a high fluorescence background from freely moving and immobile fluorescent proteins in the nucleus masks the aggregation of proteins at sparse DNA damage sites. Currently, the kinetics of these repair proteins are studied by laser-induced damage and Fluorescence Recovery After Photobleaching that rely on the detectability of high fluorescence intensity spots of clustered DNA damage. We report on the use of Number and Brightness (N&B) analysis methods as a means to monitor kinetics of DNA repair proteins during sparse DNA damage created by γ-irradiation, which is more relevant to cancer treatment than laser-induced clustered damage. We use two key double strand break repair proteins, namely Ku 70/80 and the DNA-dependent protein kinase catalytic subunit (DNA-PKCS), as specific examples to showcase the feasibility of the proposed methods to quantify dose-dependent kinetics for DNA repair proteins after exposure to γ-rays.

  2. Evolution of bulgeless low surface brightness galaxies

    Science.gov (United States)

    Shao, X.; Hammer, F.; Yang, Y. B.; Liang, Y. C.

    Based on the Sloan Digital Sky Survey DR 7, we investigate the environment, morphology, and stellar population of bulgeless low surface-brightness (LSB) galaxies in a volume-limited sample with redshift ranging from 0.024 to 0.04 and M r LSB galaxies have more young stars and are more metal-poor than regular LSB galaxies. These results suggest that the evolution of LSB galaxies may be driven by their dynamics, including mergers rather than by their large-scale environment.

  3. The radio properties of bright Seyfert galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Giuricin, G.; Mardirossian, F.; Mezzetti, M.; Bertotti, G. (Centro Interuniversitario Regionale per l' Astrofisica e la Cosmologia (Italy) Centre for Advanced Research in Space Optics (Italy))

    1990-03-01

    The radio properties of a sample of 69 bright spectroscopically selected Seyfert galaxies, which suffers from little bias toward Markarian galaxies with strong UV excess. At variance with most of the earlier results, generally based on galaxy samples which are strongly biased toward the inclusion of Markarian objects, there is no clear evidence of a significant difference in the major radio properties (radio power, radio-to-optical luminosity ratio, radio spectral index and radio size) of type 1 and type 2 Seyferts. The resulting observational scenario appears now to be more consistent than before with the idea that Seyfert 2 galaxies are simply Seyfert 1 obscured objects. 70 refs.

  4. The role of the Fraunhofer lines in solar brightness variability

    CERN Document Server

    Shapiro, A I; Krivova, N A; Tagirov, R V; Schmutz, W K

    2015-01-01

    The solar brightness varies on timescales from minutes to decades. A clear identification of the physical processes behind such variations is needed for developing and improving physics-based models of solar brightness variability and reconstructing solar brightness in the past. This is, in turn, important for better understanding the solar-terrestrial and solar-stellar connections. We estimate the relative contributions of the continuum, molecular, and atomic lines to the solar brightness variations on different timescales. Our approach is based on the assumption that variability of the solar brightness on timescales greater than a day is driven by the evolution of the solar surface magnetic field. We calculated the solar brightness variations employing the solar disc area coverage of magnetic features deduced from the MDI/SOHO observations. The brightness contrasts of magnetic features relative to the quiet Sun were calculated with a non-LTE radiative transfer code as functions of disc position and waveleng...

  5. Brightness through Local Constraint-LNA-Enhanced FIT Hybridization Probes for In Vivo Ribonucleotide Particle Tracking

    DEFF Research Database (Denmark)

    Hövelmann, Felix; Gaspar, Imre; Loibl, Simon

    2014-01-01

    Imaging the dynamics of RNA in living cells is usually performed by means of transgenic approaches that require modification of RNA targets and cells. Fluorogenic hybridization probes would also allow the analysis of wild-type organisms. We developed nuclease-resistant DNA forced intercalation (FIT......) probes that combine the high enhancement of fluorescence upon hybridization with the high brightness required to allow tracking of individual ribonucleotide particles (RNPs). In our design, a single thiazole orange (TO) intercalator dye is linked as a nucleobase surrogate and an adjacent locked nucleic...

  6. Synthesis of BODIPY derivatives substituted with various bioconjugatable linker groups: a construction kit for fluorescent labeling of receptor ligands.

    Science.gov (United States)

    Heisig, Fabian; Gollos, Sabrina; Freudenthal, Sven J; El-Tayeb, Ali; Iqbal, Jamshed; Müller, Christa E

    2014-01-01

    The goal of the present study was to design small, functionalized green-emitting BODIPY dyes, which can readily be coupled to target molecules such as receptor ligands, or even be integrated into their pharmacophores. A simple two-step one-pot procedure starting from 2,4-dimethylpyrrole and ω-bromoalkylcarboxylic acid chlorides was used to obtain new ω-bromoalkyl-substituted BODIPY fluorophores (1a-1f) connected via alkyl spacers of different length to the 8-position of the fluorescent dye. The addition of radical inhibitors reduced the amount of side products. The ω-bromoalkyl-substituted BODIPYs were further converted to introduce various functional groups: iodo-substituted dyes were obtained by Finkelstein reaction in excellent yields; microwave-assisted reaction with methanolic ammonia led to fast and clean conversion to the amino-substituted dyes; a hydroxyl-substituted derivative was prepared by reaction with sodium ethylate, and thiol-substituted BODIPYs were obtained by reaction of 1a-1f with potassium thioacetate followed by alkaline cleavage of the thioesters. Water-soluble derivatives were prepared by introducing sulfonate groups into the 2- and 6-position of the BODIPY core. The synthesized BODIPY derivatives showed high fluorescent yields and appeared to be stable under basic, reducing and oxidative conditions. As a proof of concept, 2-thioadenosine was alkylated with bromoethyl-BODIPY 1b. The resulting fluorescent 2-substituted adenosine derivative 15 displayed selectivity for the A3 adenosine receptor (ARs) over the other AR subtypes, showed agonistic activity, and may thus become a useful tool for studying A3ARs, or a lead structure for further optimization. The new functionalized dyes may be widely used for fluorescent labeling allowing the investigation of biological targets and processes.

  7. Spectral evolution of bright NS LMXBs

    CERN Document Server

    Paizis, A; Mainardi, L I; Titarchuk, L

    2010-01-01

    Theoretical and observational support suggests that the spectral evolution of neutron-star LMXBs, including transient hard X-ray tails, may be explained by the interplay between thermal and bulk motion Comptonization. In this framework, we developed a new model for the X-ray spectral fitting XSPEC package which takes into account the effects of both thermal and dynamical (i.e. bulk) Comptonization, CompTB. Using data from the INTEGRAL satellite, we tested our model on broad band spectra of a sample of persistently low magnetic field bright neutron star Low Mass X-ray Binaries, covering different spectral states. The case of the bright source GX 5-1 is presented here. Particular attention is given to the transient powerlaw-like hard X-ray (above 30 keV) tail that we interpret in the framework of the bulk motion Comptonization process, qualitatively describing the physical conditions of the environment in the innermost part of the system.

  8. Sublimation in bright spots on (1) Ceres.

    Science.gov (United States)

    Nathues, A; Hoffmann, M; Schaefer, M; Le Corre, L; Reddy, V; Platz, T; Cloutis, E A; Christensen, U; Kneissl, T; Li, J-Y; Mengel, K; Schmedemann, N; Schaefer, T; Russell, C T; Applin, D M; Buczkowski, D L; Izawa, M R M; Keller, H U; O'Brien, D P; Pieters, C M; Raymond, C A; Ripken, J; Schenk, P M; Schmidt, B E; Sierks, H; Sykes, M V; Thangjam, G S; Vincent, J-B

    2015-12-10

    The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5-7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the 'snow line', which is the distance from the Sun at which water molecules condense.

  9. Internetwork chromospheric bright grains observed with IRIS

    CERN Document Server

    Martínez-Sykora, Juan; Carlsson, Mats; De Pontieu, Bart; Pereira, Tiago M D; Boerner, Paul; Hurlburt, Neal; Kleint, Lucia; Lemen, James; Tarbell, Ted D; Title, Alan; Wuelser, Jean-Pierre; Hansteen, Viggo H; Golub, Leon; McKillop, Sean; Reeves, Kathy K; Saar, Steven; Testa, Paola; Tian, Hui; Jaeggli, Sarah; Kankelborg, Charles

    2015-01-01

    The Interface Region Imaging Spectrograph (IRIS) reveals small-scale rapid brightenings in the form of bright grains all over coronal holes and the quiet sun. These bright grains are seen with the IRIS 1330 \\AA, 1400 \\AA\\ and 2796 \\AA\\ slit-jaw filters. We combine coordinated observations with IRIS and from the ground with the Swedish 1-m Solar Telescope (SST) which allows us to have chromospheric (Ca II 8542 \\AA, Ca II H 3968 \\AA, H\\alpha, and Mg II k 2796 \\AA), and transition region (C II 1334 \\AA, Si IV 1402) spectral imaging, and single-wavelength Stokes maps in Fe I 6302 \\AA at high spatial (0.33"), temporal and spectral resolution. We conclude that the IRIS slit-jaw grains are the counterpart of so-called acoustic grains, i.e., resulting from chromospheric acoustic waves in a non-magnetic environment. We compare slit-jaw images with spectra from the IRIS spectrograph. We conclude that the grain intensity in the 2796 \\AA\\ slit-jaw filter comes from both the Mg II k core and wings. The signal in the C II ...

  10. Coronal bright points associated with minifilament eruptions

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Junchao; Jiang, Yunchun; Yang, Jiayan; Bi, Yi; Li, Haidong [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Yang, Bo; Yang, Dan, E-mail: hjcsolar@ynao.ac.cn [Also at Graduate School of Chinese Academy of Sciences, Beijing, China. (China)

    2014-12-01

    Coronal bright points (CBPs) are small-scale, long-lived coronal brightenings that always correspond to photospheric network magnetic features of opposite polarity. In this paper, we subjectively adopt 30 CBPs in a coronal hole to study their eruptive behavior using data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. About one-quarter to one-third of the CBPs in the coronal hole go through one or more minifilament eruption(s) (MFE(s)) throughout their lifetimes. The MFEs occur in temporal association with the brightness maxima of CBPs and possibly result from the convergence and cancellation of underlying magnetic dipoles. Two examples of CBPs with MFEs are analyzed in detail, where minifilaments appear as dark features of a cool channel that divide the CBPs along the neutral lines of the dipoles beneath. The MFEs show the typical rising movements of filaments and mass ejections with brightenings at CBPs, similar to large-scale filament eruptions. Via differential emission measure analysis, it is found that CBPs are heated dramatically by their MFEs and the ejected plasmas in the MFEs have average temperatures close to the pre-eruption BP plasmas and electron densities typically near 10{sup 9} cm{sup –3}. These new observational results indicate that CBPs are more complex in dynamical evolution and magnetic structure than previously thought.

  11. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    ZHU ZengWei; ZHU Di; QU NingSong

    2008-01-01

    A new mechanical electrodeposition technology was proposed,and nanocrystal-line nickel deposit with bright and smooth surface was prepared in the bath without any additive agents.Unlike traditional methods,the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing.Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits,pinholes and nodules.Furthermore,comparing with the deposit prepared by tradi-tional methods,the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm.Every diffraction peak's intensity of the deposit was reduced,the preferential orientation degree of (200) decreased and those of (111) and (220) increased.The microhardness notably increased.The magnetic properties were also changed with decreased saturation magnetization and increased coercive force.It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.Key.words:electrodeposition,electroforming,hard particle,nanocrystalline,bright nickel deposits prepared by this technology.

  12. INVESTIGATION ON THE CAUSES OF EUCALYPTUS KRAFT PULP BRIGHTNESS REVERSION

    Directory of Open Access Journals (Sweden)

    Kátia M. M. Eiras

    2005-12-01

    Full Text Available Some high brightness eucalyptus Kraft pulps have shown poor brightness stability. In most cases, the causes have notbeen identified and permanent solutions have not been found. This work focused on evaluating the brightness stability profile of pulpsbleached by in sequences such as O(DC(PODD, O(DC(PODP, OD(PODD, OD(PODP, ODHT(PODD, ODHT(PODP, OA/D(PODD, OA/D(PODP, OAD(PODD and O(ZeD(PO. Brightness stability tests induced by according to Tappi UM200 procedureon samples bleached to 90±0.5% ISO. Brightness stability was measured after each bleaching stage of the various sequences andexpressed as brightness loss in % ISO. The results indicate that pulps bleached with sequences ending with a peroxide stage havehigher brightness stability compared to those ending with a chlorine dioxide stage. Pulps bleached with a standard sequence, initiatingwith a (DC stage, show brightness stability similar to that of pulp bleached by an ECF (Elementary chlorine free sequence initiatingwith a regular D0 stage. ECF sequences, initiated with hot stages produce pulps with higher brightness stability than sequencesinitiating with a regular D0 stage. The profile across the bleaching sequences shows a tendency of increased brightness stability inalkaline stages containing peroxide and decreased stability in those stages containing chlorine and/or chlorine dioxide, parallelingpulp carbonyl group content.

  13. Tailoring cyanine dark states for improved optically modulated fluorescence recovery.

    Science.gov (United States)

    Mahoney, Daniel P; Owens, Eric A; Fan, Chaoyang; Hsiang, Jung-Cheng; Henary, Maged M; Dickson, Robert M

    2015-04-02

    Cyanine dyes are well-known for their bright fluorescence and utility in biological imaging. However, cyanines also readily photoisomerize to produce nonemissive dark states. Co-illumination with a secondary, red-shifted light source on-resonance with the longer wavelength absorbing dark state reverses the photoisomerization and returns the cyanine dye to the fluorescent manifold, increasing steady-state fluorescence intensity. Modulation of this secondary light source dynamically alters emission intensity, drastically improving detection sensitivity and facilitating fluorescence signals to be recovered from an otherwise overwhelming background. Red and near-IR emitting cyanine derivatives have been synthesized with varying alkyl chain lengths and halogen substituents to alter dual-laser fluorescence enhancement. Photophysical properties and enhancement with dual laser modulation were coupled with density functional calculations to characterize substituent effects on dark state photophysics, potentially improving detection in high background biological environments.

  14. Coupling Bright and Dark Plasmonic Lattice Resonances

    CERN Document Server

    Rodriguez, S R K; Maes, B; Janssen, O T A; Vecchi, G; Rivas, J Gomez

    2011-01-01

    We demonstrate the coupling of bright and dark Surface Lattice Resonances (SLRs), which are collective Fano resonances in 2D plasmonic crystals. As a result of this coupling, a frequency stop-gap in the dispersion relation of SLRs is observed. The different field symmetries of the low and high frequency SLR bands lead to pronounced differences in their coupling to free space radiation. Standing waves of very narrow spectral width compared to localized surface plasmon resonances are formed at the high frequency band edge, while subradiant damping onsets at the low frequency band edge leading the resonance into darkness. We introduce a coupled oscillator analog to the plasmonic crystal, which serves to elucidate the physics of the coupled plasmonic resonances and to estimate very high quality factors (Q>700) for SLRs, which are the highest known for any 2D plasmonic crystal.

  15. Hybrid quantum repeater using bright coherent light.

    Science.gov (United States)

    van Loock, P; Ladd, T D; Sanaka, K; Yamaguchi, F; Nemoto, Kae; Munro, W J; Yamamoto, Y

    2006-06-23

    We describe a quantum repeater protocol for long-distance quantum communication. In this scheme, entanglement is created between qubits at intermediate stations of the channel by using a weak dispersive light-matter interaction and distributing the outgoing bright coherent-light pulses among the stations. Noisy entangled pairs of electronic spin are then prepared with high success probability via homodyne detection and postselection. The local gates for entanglement purification and swapping are deterministic and measurement-free, based upon the same coherent-light resources and weak interactions as for the initial entanglement distribution. Finally, the entanglement is stored in a nuclear-spin-based quantum memory. With our system, qubit-communication rates approaching 100 Hz over 1280 km with fidelities near 99% are possible for reasonable local gate errors.

  16. Brightness temperature for 166 radio sources

    Institute of Scientific and Technical Information of China (English)

    Jun-Hui Fan; Yong Huang; Yu-Hai Yuan; Jiang-He Yang; Yi Liu; Jun Tao; Ying Gao; Tong-Xu Hua; Rui-Guang Lin; Jiang-Shui Zhang; Jing-Yi Zhang; Yi-Ping Qin

    2009-01-01

    Using the database of the University of Michigan Radio Astronomy Observatory (UMRAO) at three radio frequencies (4.8, 8 and 14.5 GHz), we determined the short-term variability timescales for 166 radio sources. The timescales are 0.15d (2007+777) to 176.17d (0528-250) with an average timescale of △tobs=17.1±16.5d for the whole sample. The timescales are used to calculate the brightness temperatures, TB. The value of log TB is in the range of log TB = 10.47 to 19.06 K. In addition, we also estimated the boosting factor for the sources. The correlation between the polarization and the Doppler factor is also discussed.

  17. Substructure of Quiet Sun Bright Points

    CERN Document Server

    Andic, Aleksandra; Goode, Phillip R

    2010-01-01

    Since photospheric bright points (BPs) were first observed, there has been a question as to how are they structured. Are they just single flux tubes or a bundle of the flux-tubes? Surface photometry of the quiet Sun (QS) has achieved resolution close to 0.1" with the New Solar Telescope at Big Bear Solar Observatory. This resolution allowed us to detect a richer spectrum of BPs in the QS. The smallest BPs we observed with TiO 705.68 nm were 0.13", and we were able to resolve individual components in some of the BPs clusters and ribbons observed in the QS, showing that they are composed of the individual BPs. Average size of observed BPs was 0.22".

  18. 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.

  19. Tunneling Dynamics Between Atomic Bright Solitons

    CERN Document Server

    Zhao, Li-Chen; Yang, Zhan-Ying; Yang, Wen-Li

    2016-01-01

    We investigate tunneling behavior between two bright solitons in a Bose-Einstein condensate with attractive contact interactions between atoms. The explicit tunneling properties including tunneling particles and oscillation period are described analytically, which indicates that the periodic tunneling form is a nonlinear Josephson type oscillation. The results suggest that the breathing behavior of solitons comes from the tunneling mechanism in an effective double-well potential, which is quite different from the modulational instability mechanism for Akhmediev breather and K-M breather. Furthermore, we obtain a phase diagram for two soliton interaction which admits tunneling property, particle-like property, interference property, and a resonant interaction case. The explicit conditions for them are clarified based on the defined critical distance $d_c$ and spatial interference period $D$.

  20. Stability of Bright Solitons in Bose-Einstein Condensates

    Institute of Scientific and Technical Information of China (English)

    YU Hui-You; YAN Jia-Ren; XIE Qiong-Tao

    2004-01-01

    We investigate the stability of bright solitons in Bose-Einstein condensates by including a feeding term and a loss one in the Gross-Pitaevskii equation. Based on the direct approach of perturbation theory for the nonlinear Schrodinger equation, we give the explicit dependence of the height and other related quantities of bright solitons on the feeding and loss term. It is found that the three-body recombination loss plays a crucial role in stabilizing bright solitons.

  1. Research on Brightness Measurement of Intense Electron Beam

    CERN Document Server

    Wang, Yuan; Zhang, Huang; Yang, GuoJun; Li, YiDing; Li, Jin

    2015-01-01

    The mostly research fasten on high emission density of injector to study electron beam's brightness in LIA. Using the injector(2MeV) was built to research brightness of multi-pulsed high current(KA) electron beam, and researchs three measurement method (the pepper-pot method, beam collimator without magnetic field, beam collimator with magnetic field method) to detect beam's brightness with time-resolved measurement system.

  2. 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

  3. FAA Fluorescent Penetrant Laboratory Inspections

    Energy Technology Data Exchange (ETDEWEB)

    WINDES,CONNOR L.; MOORE,DAVID G.

    2000-08-02

    The Federal Aviation Administration Airworthiness Assurance NDI Validation Center currently assesses the capability of various non-destructive inspection (NDI) methods used for analyzing aircraft components. The focus of one such exercise is to evaluate the sensitivity of fluorescent liquid penetrant inspection. A baseline procedure using the water-washable fluorescent penetrant method defines a foundation for comparing the brightness of low cycle fatigue cracks in titanium test panels. The analysis of deviations in the baseline procedure will determine an acceptable range of operation for the steps in the inspection process. The data also gives insight into the depth of each crack and which step(s) of the inspection process most affect penetrant sensitivities. A set of six low cycle fatigue cracks produced in 6.35-mm thick Ti-6Al-4V specimens was used to conduct the experiments to produce sensitivity data. The results will document the consistency of the crack readings and compare previous experiments to find the best parameters for water-washable penetrant.

  4. Lifetime Resolved Fluorescence Fluctuation Spectroscopy

    Science.gov (United States)

    Guo, Peng; Berland, Keith

    2009-11-01

    Fluorescence correlation spectroscopy (FCS) has been widely used investigate molecular dynamics and interactions in biological systems. FCS typically resolves the component species of a sample either through differences in diffusion coefficient or molecular brightness. Diffusion based assays currently have a major limitation which requires that the diffusion coefficients of component species in a sample must be substantially different in order to be resolved. This criterion is not met in many important cases, such as when molecules of similar molecular weight bind to each other. This limitation can be overcome, and resolution of FCS measurements enhanced, by combining FCS measurements with measurements of fluorescence lifetimes. By using of global analysis on simultaneously acquired FCS and lifetime data we show that we can dramatically enhance resolution in FCS measurements, and accurately resolve the concentration and diffusion coefficients of multiple sample components even when their diffusion coefficients are identical provided there is a difference in the lifetime of the component species. We show examples of this technique using both simulations and experiments. It is expected that this method will be of significance for binding assays studying molecular interactions.

  5. The use of fluorescence enhancement to improve the microscopic diagnosis of falciparum malaria

    Directory of Open Access Journals (Sweden)

    Liu Paul

    2007-07-01

    Full Text Available Abstract Background Giemsa staining of thick blood smears remains the "gold standard" for detecting malaria. However, this method is not very good for diagnosing low-level infections. A method for the simultaneous staining of Plasmodium-parasitized culture and blood smears for both bright field and fluorescence was developed and its ability to improve detection efficiency tested. Methods A total of 22 nucleic acid-specific fluorescent dyes were tested for their ability to provide easily observable staining of Plasmodium falciparum-parasitized red blood cells following Giemsa staining. Results Of the 14 dyes that demonstrated intense fluorescence staining, only SYBR Green 1, YOYO-1 and ethidum homodimer-2 could be detected using fluorescent microscopy, when cells were first stained with Giemsa. Giemsa staining was not effective when applied after the fluorescent dyes. SYBR Green 1 provided the best staining in the presence of Giemsa, as a very high percentage of the parasitized cells were simultaneously stained. When blood films were screened using fluorescence microscopy the parasites were more readily detectable due to the sharp contrast between the dark background and the specific, bright fluorescence produced by the parasites. Conclusion The dual staining method reported here allows fluorescence staining, which enhances the reader's ability to detect parasites under low parasitaemia conditions, coupled with the ability to examine the same cell under bright field conditions to detect the characteristic morphology of Plasmodium species that is observed with Giemsa staining.

  6. A bright and long-pulse illumination for ultrahigh-speed microscopy of living specimens.

    Science.gov (United States)

    Nakano, Hitoshi; Yokoi, Sayoko; Yoshida, Shigeru; Yamada, Makoto; Takeuchi, Takeshi; Takehara, Kosei; Etoh, T Goji

    2010-01-01

    Ultrahigh-speed microscopy of living specimens requires ultrabright illumination. Moreover, the duration of illumination should be sufficiently long, on the order of at least several tens of milliseconds, in order to investigate the dynamic state of living specimens. However, specimens are exposed to a high risk of damage by the intense illumination. The brightness and pulse duration of illumination have to be continuously controlled for use in the ultrahigh-speed microscopy of living specimens. Commercial or laboratory-made illumination systems do not satisfy the abovementioned requirements. In this paper, the development of a bright and long-pulse illumination system for ultrahigh-speed microscopy of living specimens is presented. A xenon flashlamp with an arc length of 1.5 mm has been used as the light source. The electrical power supply consists of a voltage-regulated circuit, a capacitor bank, and a control circuit including an insulated-gate bipolar transistor as a gating device, which provides a large rectangular current pulse with the duration in the range to the order of several tens of milliseconds. The brightness, pulse duration, and repetition rate can be easily and continuously controlled. The illumination developed in the present study is installed in an inverted fluorescence microscope equipped with a high-speed camera in order to evaluate the performance as an illumination source. A fluorescent image of the living spermatozoa of a mouse obtained at a frame rate of 8 kHz shows good contrast. Such an image cannot be obtained using a commercial illumination system.

  7. Carbon "Quantum" Dots for Fluorescence Labeling of Cells.

    Science.gov (United States)

    Liu, Jia-Hui; Cao, Li; LeCroy, Gregory E; Wang, Ping; Meziani, Mohammed J; Dong, Yiyang; Liu, Yuanfang; Luo, Pengju G; Sun, Ya-Ping

    2015-09-02

    The specifically synthesized and selected carbon dots of relatively high fluorescence quantum yields were evaluated in their fluorescence labeling of cells. For the cancer cell lines, the cellular uptake of the carbon dots was generally efficient, resulting in the labeling of the cells with bright fluorescence emissions for both one- and two-photon excitations from predominantly the cell membrane and cytoplasm. In the exploration on labeling the live stem cells, the cellular uptake of the carbon dots was relatively less efficient, though fluorescence emissions could still be adequately detected in the labeled cells, with the emissions again predominantly from the cell membrane and cytoplasm. This combined with the observed more efficient internalization of the same carbon dots by the fixed stem cells might suggest some significant selectivity of the stem cells toward surface functionalities of the carbon dots. The needs and possible strategies for more systematic and comparative studies on the fluorescence labeling of different cells, including especially live stem cells, by carbon dots as a new class of brightly fluorescent probes are discussed.

  8. Larger Planet Radii Inferred from Stellar "Flicker" Brightness Variations of Bright Planet Host Stars

    CERN Document Server

    Bastien, Fabienne A; 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, logg. Recent work has demonstrated that the short-timescale brightness variations ("flicker") of stars can be used to measure logg to a high accuracy of ~0.1-0.2 dex (Bastien et al. 2013). Here, we use flicker measurements of 289 bright (Kepmag<13) candidate planet-hosting stars with Teff=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, an astrophysical bias exists that contaminates the stellar sample with evolved stars: nearly 50%...

  9. A Zn2+-specific fluorescent molecular probe for the selective detection of endogenous cyanide in biorelevant samples.

    Science.gov (United States)

    Divya, Kizhumuri P; Sreejith, Sivaramapanicker; Balakrishna, Bugga; Jayamurthy, Purushothaman; Anees, Palappuravan; Ajayaghosh, Ayyappanpillai

    2010-09-07

    A Zn(2+)-specific molecular probe 3 was developed for the selective detection of CN(-) under aqueous conditions. The fluorescent Zn(2+) complex of 3 upon CN(-) addition generates a bright blue fluorescence that allows the detection of the latter and is useful for the screening of natural products with and without endogenous cyanide content.

  10. High Brightness Neutron Source for Radiography

    Energy Technology Data Exchange (ETDEWEB)

    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

    2008-12-08

    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

  11. Forensic applications: Fluorescence properties of tooth-coloured restorative materials using a fluorescence DSLR camera.

    Science.gov (United States)

    Kiran, Ramya; Walsh, Laurence J; Forrest, Alexander; Tennant, Marc; Chapman, James

    2017-02-03

    The objective of this study was to compare the fluorescence properties of dry and wet samples of contemporary tooth-coloured restorative materials using a fluorescence based DSLR camera and a variety of LEDs emitting different wavelengths of visible light as excitation sources. The materials examined included resin composites; ceramics and hybrid restorative materials such as ormocers, Vita Enamic™ and resin reinforced glass-ionomer cements. The levels of fluorescence for each sample under different combinations of incident light wavelengths and filters was analysed by using histogram data for colour channels from Adobe Photoshop software. Fluorescence patterns were influenced by water sorption of the materials. UV-A/Violet light (405±nm) produced the greatest range of luminosity values (10-204) amongst the tooth-coloured restorative materials, and showed the greatest differences between restorations and tooth structure. The best filter combinations with violet light were orange or yellow filters. Under ultraviolet excitation, Fuji VIII A2 exhibited a unique bright pink fluorescence emission, while VitaEnamic™, ormocer and glass-ionomer cements emitted bluish-pink fluorescence emissions. In conclusion, restorative materials exhibited varied emission pattern under UV-A (405nm) light, which enables their detection and differentiation from natural tooth structure.

  12. Fundamentals of fluorescence and fluorescence microscopy.

    Science.gov (United States)

    Wolf, David E

    2013-01-01

    This chapter discusses the fundamental physics of fluorescence. The application of fluorescence to microscopy represents an important transition in the development of microscopy, particularly as it applies to biology. It enables quantitating the amounts of specific molecules within a cell, determining whether molecules are complexing on a molecular level, measuring changes in ionic concentrations within cells and organelles, and measuring molecular dynamics. This chapter also discusses the issues important to quantitative measurement of fluorescence and focuses on four of quantitative measurements of fluorescence--boxcar-gated detection, streak cameras, photon correlation, and phase modulation. Although quantitative measurement presents many pitfalls to the beginner, it also presents significant opportunities to one skilled in the art. This chapter also examines how fluorescence is measured in the steady state and time domain and how fluorescence is applied in the modern epifluorescence microscope.

  13. 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.

  14. GOMOS bright limb ozone data set

    Directory of Open Access Journals (Sweden)

    S. Tukiainen

    2015-01-01

    Full Text Available We have created a daytime ozone profile data set from the measurements of the Global Ozone Monitoring by Occultation of Stars (GOMOS instrument on board the Envisat satellite. This so-called GOMOS bright limb (GBL data set contains ~ 358 000 stratospheric daytime ozone profiles measured by GOMOS in 2002–2012. The GBL data set complements the widely used GOMOS night-time data based on stellar occultation measurements. The GBL data set is based on the GOMOS daytime occultations but instead of the transmitted star light, we use limb scattered solar light. The ozone profiles retrieved from these radiance spectra cover 18–60 km tangent height range and have approximately 2–3 km vertical resolution. We show that these profiles are generally in better than 10% agreement with the NDACC (Network for the Detection of Atmospheric Composition Change ozone sounding profiles and with the GOMOS night-time, MLS (Microwave Limb Sounder, and OSIRIS (Optical Spectrograph, and InfraRed Imaging System satellite measurements. However, there is a 10–13% negative bias at 40 km tangent height and a 10–50% positive bias at 50 km when the solar zenith angle > 75°. These biases are most likely caused by stray light which is difficult to characterize and remove entirely from the measured spectra. Nevertheless, the GBL data set approximately doubles the amount of useful GOMOS ozone profiles and improves coverage of the summer pole.

  15. Mechanical electrodeposition of bright nanocrystalline nickel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new mechanical electrodeposition technology was proposed, and nanocrystalline nickel deposit with bright and smooth surface was prepared in the bath without any additive agents. Unlike traditional methods, the novel technology employed dynamical hard particles to continuously polish the cathode surface and disturb the nearby solution during electrodepositing. Experimental results showed that the polishing effect of hard particles can effectively prevent the hydrogen bubbles and impurities from adhering on the deposit surface and avoid the production of pits, pinholes and nodules. Furthermore, comparing with the deposit prepared by traditional methods, the one prepared by the novel technology was substantially refined with grain size ranging from 30 to 80 nm. Every diffraction peak’s intensity of the deposit was reduced, the preferential orientation degree of (200) decreased and those of (111) and (220) increased. The microhardness notably increased. The magnetic properties were also changed with decreased saturation magnetization and increased coercive force. It was also found that variation of current density and cathode rotational speed could affect the structure and properties of the nickel deposits prepared by this technology.

  16. 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.

  17. Spatial Model of Sky Brightness Magnitude in Langkawi Island, Malaysia

    Science.gov (United States)

    Redzuan Tahar, Mohammad; Kamarudin, Farahana; Umar, Roslan; Khairul Amri Kamarudin, Mohd; Hazmin Sabri, Nor; Ahmad, Karzaman; Rahim, Sobri Abdul; Sharul Aikal Baharim, Mohd

    2017-03-01

    Sky brightness is an essential topic in the field of astronomy, especially for optical astronomical observations that need very clear and dark sky conditions. This study presents the spatial model of sky brightness magnitude in Langkawi Island, Malaysia. Two types of Sky Quality Meter (SQM) manufactured by Unihedron are used to measure the sky brightness on a moonless night (or when the Moon is below the horizon), when the sky is cloudless and the locations are at least 100 m from the nearest light source. The selected locations are marked by their GPS coordinates. The sky brightness data obtained in this study were interpolated and analyzed using a Geographic Information System (GIS), thus producing a spatial model of sky brightness that clearly shows the dark and bright sky areas in Langkawi Island. Surprisingly, our results show the existence of a few dark sites nearby areas of high human activity. The sky brightness of 21.45 mag arcsec{}-2 in the Johnson-Cousins V-band, as the average of sky brightness equivalent to 2.8 × {10}-4{cd} {{{m}}}-2 over the entire island, is an indication that the island is, overall, still relatively dark. However, the amount of development taking place might reduce the number in the near future as the island is famous as a holiday destination.

  18. Brightness limitations of cold field emitters caused by Coulomb interactions

    NARCIS (Netherlands)

    Cook, B.J.; Verduin, T.; Hagen, C.W.; Kruit, P.

    2010-01-01

    Emission theory predicts that high brightness cold field emitters can enhance imaging in the electron microscope. This (neglecting chromatic aberration) is because of the large (coherent) probe current available from a high brightness source and is based on theoretically determined values of reduced

  19. Surface photometry of bulge dominated low surface brightness galaxies

    NARCIS (Netherlands)

    Beijersbergen, M; de Blok, WJG; van der Hulst, JM

    1999-01-01

    We present results of broad band BVRI observations of a sample of galaxies with a low surface brightness (LSB) disk and a bulge. These galaxies are well described as exponential disks and exponential bulges with no preferred value for either scale length or central surface brightness. The median B b

  20. 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...

  1. 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.

  2. Ultra-fast bright field and fluorescence imaging of the dynamics of micrometer-sized objects

    NARCIS (Netherlands)

    Chen, X.C.; Wang, J.J.; Versluis, M.; Jong, de N.; Villanueva, F.S.

    2013-01-01

    High speed imaging has application in a wide area of industry and scientific research. In medical research, high speed imaging has the potential to reveal insight into mechanisms of action of various therapeutic interventions. Examples include ultrasound assisted thrombolysis, drug delivery, and gen

  3. Measurement of the Color Characteristics and Brightness of Fluorescent and Phosphorescent Material

    Science.gov (United States)

    1947-06-01

    diagram. - A straight line drawn through the points on the chromaticity diagram corresponding __..- to a given illuminant (usually Iluminant "C") and the...distance from the point of the unknown color to the point of illuminant "C" to the distance from iluminant "C" to the intersection with the line of pure

  4. Interpreting Central Surface Brightness and Color Profiles in Elliptical Galaxies

    Science.gov (United States)

    Silva, David R.; Wise, Michael W.

    1996-01-01

    Hubble Space Telescope imagery has revealed dust features in the central regions of many (50%--80%) nearby bright elliptical galaxies. If these features are an indication of an underlying smooth diffuse dust distribution, then the interpretation of central surface brightness and color profiles in elliptical galaxies becomes significantly more difficult. In this Letter, diagnostics for constraining the presence of such an underlying central dust distribution are presented. We show that easily detectable central color gradients and flattened central surface brightness profiles can be induced by even small amounts of smoothly distributed dust (~100 M⊙). Conversely, combinations of flat surface brightness profiles and flat color gradients or steep surface brightness profiles and steep color gradients are unlikely to be caused by dust. Taken as a whole, these results provide a simple observational tautology for constraining the existence of smooth diffuse dust distributions in the central regions of elliptical galaxies.

  5. Automated local bright feature image analysis of nuclear proteindistribution identifies changes in tissue phenotype

    Energy Technology Data Exchange (ETDEWEB)

    Knowles, David; Sudar, Damir; Bator, Carol; Bissell, Mina

    2006-02-01

    The organization of nuclear proteins is linked to cell and tissue phenotypes. When cells arrest proliferation, undergo apoptosis, or differentiate, the distribution of nuclear proteins changes. Conversely, forced alteration of the distribution of nuclear proteins modifies cell phenotype. Immunostaining and fluorescence microscopy have been critical for such findings. However, there is an increasing need for quantitative analysis of nuclear protein distribution to decipher epigenetic relationships between nuclear structure and cell phenotype, and to unravel the mechanisms linking nuclear structure and function. We have developed imaging methods to quantify the distribution of fluorescently-stained nuclear protein NuMA in different mammary phenotypes obtained using three-dimensional cell culture. Automated image segmentation of DAPI-stained nuclei was generated to isolate thousands of nuclei from three-dimensional confocal images. Prominent features of fluorescently-stained NuMA were detected using a novel local bright feature analysis technique, and their normalized spatial density calculated as a function of the distance from the nuclear perimeter to its center. The results revealed marked changes in the distribution of the density of NuMA bright features as non-neoplastic cells underwent phenotypically normal acinar morphogenesis. In contrast, we did not detect any reorganization of NuMA during the formation of tumor nodules by malignant cells. Importantly, the analysis also discriminated proliferating non-neoplastic cells from proliferating malignant cells, suggesting that these imaging methods are capable of identifying alterations linked not only to the proliferation status but also to the malignant character of cells. We believe that this quantitative analysis will have additional applications for classifying normal and pathological tissues.

  6. Principles of fluorescence techniques

    CERN Document Server

    2016-01-01

    Fluorescence techniques are being used and applied increasingly in academics and industry. The Principles of Fluorescence Techniques course will outline the basic concepts of fluorescence techniques and the successful utilization of the currently available commercial instrumentation. The course is designed for students who utilize fluorescence techniques and instrumentation and for researchers and industrial scientists who wish to deepen their knowledge of fluorescence applications. Key scientists in the field will deliver theoretical lectures. The lectures will be complemented by the direct utilization of steady-state and lifetime fluorescence instrumentation and confocal microscopy for FLIM and FRET applications provided by leading companies.

  7. Reviews in fluorescence 2010

    CERN Document Server

    Geddes, Chris D

    2011-01-01

    ""Reviews in Fluorescence 2010"", the seventh volume of the book serial from Springer, serves as a comprehensive collection of current trends and emerging hot topics in the field of fluorescence and closely related disciplines. It summarizes the year's progress in fluorescence and its applications, with authoritative analytical reviews specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of fluorescence. ""Reviews in Fluorescence"" offers an essential reference material for any lab working in the fluoresc

  8. 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

  9. Dark Skies, Bright Kids: Year 2

    Science.gov (United States)

    Carlberg, Joleen K.; Johnson, K.; Lynch, R.; Walker, L.; Beaton, R.; Corby, J.; de Messieres, G.; Drosback, M.; Gugliucci, N.; Jackson, L.; Kingery, A.; Layman, S.; Murphy, E.; Richardson, W.; Ries, P.; Romero, C.; Sivakoff, G.; Sokal, K.; Trammell, G.; Whelan, D.; Yang, A.; Zasowski, G.

    2011-01-01

    The Dark Skies, Bright Kids (DSBK) outreach program brings astronomy education into local elementary schools in central Virginia's Southern Albemarle County through an after-school club. Taking advantage of the unusually dark night skies in the rural countryside, DSBK targets economically disadvantaged schools that tend to be underserved due to their rural locale. The goals of DSBK are to foster children's natural curiosity, demonstrate that science is a fun and creative process, challenge students' conceptions of what a scientist is and does, and teach some basic astronomy. Furthermore, DSBK works to assimilate families into students' education by holding family observing nights at the school. Now in its third semester, DSBK has successfully run programs at two schools with very diverse student populations. Working with these students has helped us to revise our activities and to create new ones. A by-product of our work has been the development of lesson plans, complete with learning goals and detailed instructions, that we make publically available on our website. This year we are expanding our repertoire with our new planetarium, which allows us to visualize topics in novel ways and supplements family observing on cloudy nights. The DSBK volunteers have also created a bilingual astronomy artbook --- designed, written, and illustrated by UVa students --- that we will publish and distribute to elementary schools in Virginia. Our book debuted at the last AAS winter meeting, and since then it has been extensively revised and updated with input from many individuals, including parents, professional educators, and a children's book author. Because the club is currently limited to serving a few elementary schools, this book will be part of our efforts to broaden our impact by bringing astronomy to schools we cannot go to ourselves and reaching out to Spanish-speaking communities at the same time.

  10. 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.

  11. Bright Times for an Ancient Star

    Science.gov (United States)

    Fuhrmann, K.; Chini, R.

    2017-01-01

    Field stars of Population II are among the oldest sources in the Galaxy. Most of their solar-type dwarfs are non-single and, given their extreme age, a significant fraction is accompanied by stellar remnants. Here we report the discovery of the bright F7V star 49 Lib as a massive and very metal-rich Population II field blue straggler, along with evidence for a white dwarf as its dark and unseen companion. 49 Lib is known as a relatively fast-rotating, single-lined spectroscopic binary in a 3 year orbit and with an apparent age of about τ ≃ 2.3 Gyr. Its chemistry and kinematics, however, both consistently imply that 49 Lib must be an ancient Population II star at τ ≃ 12 Gyr. With reference to the inclination from the astrometric orbit, leading to a {M}{WD}={0.50}-0.04+0.03 M⊙ low-mass white dwarf, and in view of the {M}{BS}={1.55}-0.13+0.07 M⊙ massive, evolved F-type blue straggler star, we demonstrate that 49 Lib must have been the subject of a mostly conservative mass transfer with a near-equal-mass M ≃ 1.06 + 1.00 M⊙ G-type binary at birth. For its future evolution, we point to the possibility as a progenitor system toward a type Ia supernova. Most importantly, however, we note that the remarkable metal enrichment of 49 Lib at [Mg/H] = +0.23 and [Fe/H] = ‑0.11 has principally very relevant implications for the early epoch when the Milky Way came into being.

  12. MAGNETIC FLUX SUPPLEMENT TO CORONAL BRIGHT POINTS

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Chaozhou; Huang, Zhenghua; Xia, Lidong; Li, Bo; Fu, Hui; Jiao, Fangran; Hou, Zhenyong [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai, 264209 Shandong (China); Madjarska, Maria S., E-mail: z.huang@sdu.edu.cn [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom)

    2016-02-10

    Coronal bright points (BPs) are associated with magnetic bipolar features (MBFs) and magnetic cancellation. Here we investigate how BP-associated MBFs form and how the consequent magnetic cancellation occurs. We analyze longitudinal magnetograms from the Helioseismic and Magnetic Imager to investigate the photospheric magnetic flux evolution of 70 BPs. From images taken in the 193 Å passband of the Atmospheric Imaging Assembly (AIA) we dermine that the BPs’ lifetimes vary from 2.7 to 58.8 hr. The formation of the BP MBFs is found to involve three processes, namely, emergence, convergence, and local coalescence of the magnetic fluxes. The formation of an MBF can involve more than one of these processes. Out of the 70 cases, flux emergence is the main process of an MBF buildup of 52 BPs, mainly convergence is seen in 28, and 14 cases are associated with local coalescence. For MBFs formed by bipolar emergence, the time difference between the flux emergence and the BP appearance in the AIA 193 Å passband varies from 0.1 to 3.2 hr with an average of 1.3 hr. While magnetic cancellation is found in all 70 BPs, it can occur in three different ways: (I) between an MBF and small weak magnetic features (in 33 BPs); (II) within an MBF with the two polarities moving toward each other from a large distance (34 BPs); (III) within an MBF whose two main polarities emerge in the same place simultaneously (3 BPs). While an MBF builds up the skeleton of a BP, we find that the magnetic activities responsible for the BP heating may involve small weak fields.

  13. Mapping molecules in scanning far-field fluorescence nanoscopy

    Science.gov (United States)

    Ta, Haisen; Keller, Jan; Haltmeier, Markus; Saka, Sinem K.; Schmied, Jürgen; Opazo, Felipe; Tinnefeld, Philip; Munk, Axel; Hell, Stefan W.

    2015-08-01

    In fluorescence microscopy, the distribution of the emitting molecule number in space is usually obtained by dividing the measured fluorescence by that of a single emitter. However, the brightness of individual emitters may vary strongly in the sample or be inaccessible. Moreover, with increasing (super-) resolution, fewer molecules are found per pixel, making this approach unreliable. Here we map the distribution of molecules by exploiting the fact that a single molecule emits only a single photon at a time. Thus, by analysing the simultaneous arrival of multiple photons during confocal imaging, we can establish the number and local brightness of typically up to 20 molecules per confocal (diffraction sized) recording volume. Subsequent recording by stimulated emission depletion microscopy provides the distribution of the number of molecules with subdiffraction resolution. The method is applied to mapping the three-dimensional nanoscale organization of internalized transferrin receptors on human HEK293 cells.

  14. Plasmonic-enhanced two-photon fluorescence with single gold nanoshell

    Science.gov (United States)

    Zhang, TianYue; Lu, GuoWei; Shen, HongMing; Perriat, P.; Martini, M.; Tillement, O.; Gong, QiHuang

    2014-06-01

    Single gold nanoshell with mutilpolar plasmon resonances is proposed to enhance two-photon fluorescence efficiently. The single emitter single nanoshell configuration is studied systematically by employing the finite-difference time-domain method. The emitter located inside or outside the nanoshell at various positions leads to a significantly different enhancement effect. The fluorescent emitter placed outside the nanoshell can achieve large fluorescence intensity given that both the position and orientation of the emission dipole are optimally controlled. In contrast, for the case of the emitter placed inside the nanoshell, it can experience substantial two-photon fluorescence enhancement without strict requirements upon the position and dipole orientations. Metallic nanoshell encapsulating many fluorescent emitters should be a promising nanocomposite configuration for bright two-photon fluorescence label. The results provide a comprehensive understanding about the plasmonic-enhanced two-photon fluorescence behaviors, and the nanocomposite configuration has great potential for optical detecting, imaging and sensing in biological applications.

  15. Fluorescent nanodiamonds embedded in biocompatible translucent shells.

    Science.gov (United States)

    Rehor, Ivan; Slegerova, Jitka; Kucka, Jan; Proks, Vladimir; Petrakova, Vladimira; Adam, Marie-Pierre; Treussart, François; Turner, Stuart; Bals, Sara; Sacha, Pavel; Ledvina, Miroslav; Wen, Amy M; Steinmetz, Nicole F; Cigler, Petr

    2014-03-26

    High pressure high temperature (HPHT) nanodiamonds (NDs) represent extremely promising materials for construction of fluorescent nanoprobes and nanosensors. However, some properties of bare NDs limit their direct use in these applications: they precipitate in biological solutions, only a limited set of bio-orthogonal conjugation techniques is available and the accessible material is greatly polydisperse in shape. In this work, we encapsulate bright 30-nm fluorescent nanodiamonds (FNDs) in 10-20-nm thick translucent (i.e., not altering FND fluorescence) silica shells, yielding monodisperse near-spherical particles of mean diameter 66 nm. High yield modification of the shells with PEG chains stabilizes the particles in ionic solutions, making them applicable in biological environments. We further modify the opposite ends of PEG chains with fluorescent dyes or vectoring peptide using click chemistry. High conversion of this bio-orthogonal coupling yielded circa 2000 dye or peptide molecules on a single FND. We demonstrate the superior properties of these particles by in vitro interaction with human prostate cancer cells: while bare nanodiamonds strongly aggregate in the buffer and adsorb onto the cell membrane, the shell encapsulated NDs do not adsorb nonspecifically and they penetrate inside the cells.

  16. Fluorescence correlation spectroscopy

    NARCIS (Netherlands)

    Hink, M.A.; Verveer, P.J.

    2015-01-01

    Fluorescence fluctuation spectroscopy techniques allow the quantification of fluorescent molecules present at the nanomolar concentration level. After a brief introduction to the technique, this chapter presents a protocol including background information in order to measure and quantify the molecul

  17. Live Cell Surface Labeling with Fluorescent Ag Nanocluster Conjugates†

    OpenAIRE

    Yu, Junhua; Choi, Sungmoon; Richards, Chris I.; Antoku, Yasuko; Dickson, Robert M

    2008-01-01

    DNA-encapsulated silver clusters are readily conjugated to proteins and serve as alternatives to organic dyes and semiconductor quantum dots. Stable and bright on the bulk and single molecule levels, Ag nanocluster fluorescence is readily observed when staining live cell surfaces. Being significantly brighter and more photostable than organics and much smaller than quantum dots with a single point of attachment, these nanomaterials offer promising new approaches for bulk and single molecule b...

  18. Nanoluciferase signal brightness using furimazine substrates opens bioluminescence resonance energy transfer to widefield microscopy.

    Science.gov (United States)

    Kim, Jiho; Grailhe, Regis

    2016-08-01

    Fluorescence and bioluminescence resonance energy transfer (FRET, BRET) techniques are powerful tools for studying protein-protein interactions in cellular assays. In contrast to fluorescent proteins, chemiluminescent proteins do not require excitation light, known to trigger autofluorescence, phototoxicity, and photobleaching. Regrettably, low signal intensity of luciferase systems restricts their usage as they require specialized microscopes equipped with ultra low-light imaging cameras. In this study, we report that bioluminescence quantification in living cells using a standard widefield automated microscope dedicated to screening and high content analysis is possible with the newer luciferase systems, Nanoluciferase (Nluc). With such equipment, we showed that robust intramolecular BRET can be measured using a combination of Nluc and yellow fluorescent protein (YFP). Using the human Superoxide Dismutase 1 (SOD1) dimer model, we next validated that intermolecular BRET could be quantified at a single cell level. The enhanced signal brightness of Nluc enabling BRET imaging to widefield microscopy shows strong potential to open up single cell protein-protein interactions studies to a wider audience. © 2016 International Society for Advancement of Cytometry.

  19. Safe biodegradable fluorescent particles

    Science.gov (United States)

    Martin, Sue I.; Fergenson, David P.; Srivastava, Abneesh; Bogan, Michael J.; Riot, Vincent J.; Frank, Matthias

    2010-08-24

    A human-safe fluorescence particle that can be used for fluorescence detection instruments or act as a safe simulant for mimicking the fluorescence properties of microorganisms. The particle comprises a non-biological carrier and natural fluorophores encapsulated in the non-biological carrier. By doping biodegradable-polymer drug delivery microspheres with natural or synthetic fluorophores, the desired fluorescence can be attained or biological organisms can be simulated without the associated risks and logistical difficulties of live microorganisms.

  20. Variations in the Bivariate Brightness Distribution with different galaxy types

    CERN Document Server

    Cross, N; Lemon, D; Liske, J; Cross, Nicholas; Driver, Simon; Lemon, David; Liske, Jochen

    2002-01-01

    We present Bivariate Brightness Distributions (BBDs) for four spectral types discriminated by the 2dFGRS. We discuss the photometry and completeness of the 2dFGRS using a deep, wide-field CCD imaging survey. We find that there is a strong luminosity-surface brightness correlation amongst galaxies with medium to strong emission features, with gradient $\\beta_{\\mu}=0.25\\pm0.05$ and width $\\sigma_{\\mu}=0.56\\pm0.01$. Strong absorption line galaxies, show a bimodal distribution, with no correlation between luminosity and surface brightness.

  1. 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...

  2. SMEX03 SSM/I Brightness Temperature Data, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides brightness temperature data acquired during the Soil Moisture Experiment 2003 (SMEX03) by the Special Sensor Microwave/Imager (SSM/I). The...

  3. 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].

  4. Bright Prospect for the Polyester Industrial Filament Sector

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Some large companies from Americaand Europe have constructed plantsin China or established long-termstable cooperation relationship withChinese enterprises. A bright devel-opment prospect has therefore beenbrought to the polyester industrial fila-ment sector in China.

  5. An observational correlation between stellar brightness variations and surface gravity

    CERN Document Server

    Bastien, Fabienne A; Basri, Gibor; Pepper, Joshua

    2013-01-01

    Surface gravity is one of a star's basic properties, but it is difficult to measure accurately, with typical uncertainties of 25-50 per cent if measured spectroscopically and 90-150 per cent photometrically. Asteroseismology measures gravity with an uncertainty of about two per cent but is restricted to relatively small samples of bright stars, most of which are giants. The availability of high-precision measurements of brightness variations for >150,000 stars provides an opportunity to investigate whether the variations can be used to determine surface gravities. The Fourier power of granulation on a star's surface correlates physically with surface gravity; if brightness variations on timescales of hours arise from granulation, then such variations should correlate with surface gravity. Here we report an analysis of archival data that reveals an observational correlation between surface gravity and the root-mean-square brightness variations on timescales of less than eight hours for stars with temperatures ...

  6. SMEX03 SSM/I Brightness Temperature Data, Georgia

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides brightness temperature data acquired during the Soil Moisture Experiment 2003 (SMEX03) by the Special Sensor Microwave/Imager (SSM/I). The...

  7. 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...

  8. Ultra High Brightness/Low Cost Fiber Coupled Packaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The focus of the proposed effort is maximizing the brightness of fiber coupled laser diode pump sources at a minimum cost. The specific innovation proposed is to...

  9. Gd(iii)-doped carbon dots as a dual fluorescent-MRI probe

    KAUST Repository

    Bourlinos, Athanasios B.

    2012-01-01

    We describe the synthesis of Gd(iii)-doped carbon dots as dual fluorescence-MRI probes for biomedical applications. The derived Gd(iii)-doped carbon dots show uniform particle size (3-4 nm) and gadolinium distribution and form stable dispersions in water. More importantly, they exhibit bright fluorescence, strong T1-weighted MRI contrast and low cytotoxicity. © The Royal Society of Chemistry 2012.

  10. Supercontinuum generation with bright and dark solitons in optical fibers

    CERN Document Server

    Milián, Carles; Kudlinski, Alexandre; Skryabin, Dmitry V

    2016-01-01

    We study numerically and experimentally supercontinuum generation in optical fibers with dark and bright solitons simultaneously contributing into the spectral broadening and dispersive wave generation. We report a novel type of weak trapped radiation arising due to interaction of bright solitons with the dark soliton background. This radiation expresses itself as two pulses with the continuously shifting spectra constituting the short and long wavelength limits of the continuum. Our theoretical and experimental results are in good agreement.

  11. Imaging dynamic cellular events with quantum dots The bright future

    OpenAIRE

    Smith, Andrew M.; Wen, Mary M.; Nie, Shuming

    2010-01-01

    Semiconductor quantum dots (QDs) are tiny light-emitting particles that have emerged as a new class of fluorescent labels for biology and medicine. Compared with traditional fluorescent probes, QDs have unique optical and electronic properties such as size-tuneable light emission, narrow and symmetric emission spectra, and broad absorption spectra that enable the simultaneous excitation of multiple fluorescence colours.

  12. Global View of the Bright Material on Vesta

    Science.gov (United States)

    Zambon, F.; DeSanctis, C.; Schroeder, S.; Tosi, F.; Li, J.-Y.; Longobardo, A.; Ammannito, E.; Blewett, D. T.; Palomba, E.; Capaccioni, F.; Frigeri, A.; Capria, M. T.; Fonte, S.; Mittlefehldt, D. W.; Nathues, A.; Pieters, C.; Russell, C. T.; Raymond, C. A.

    2014-01-01

    At 525 km in mean diameter, Vesta is the second-most massive and one of the brightest asteroids of the main-belt. Here we give a global view of the bright material (BM) units on Vesta. We classified the BMs according to the normal visual albedo. The global albedo map of Vesta allows to be divided the surface into three principal types of terrains: bright regions, dark regions and intermediate regions. The distribution of bright regions is not uniform. The mid-southern latitudes contain the most bright areas, while the northern hemisphere is poor in bright regions. The analysis of the spectral parameters and the normal visual albedo show a dependence between albedo and the strength (depth) of ferrous iron absorption bands, strong bands correspond with high albedo units. Vesta's average albedo is 0.38, but there are bright material whose albedo can exceed 0.50. Only the E-Type asteroids have albedos comparable to those of the BMs on Vesta. The Dawn mission observed a large fraction of Vesta's surface at high spatial resolution, allowing a detailed study of the morphology and mineralogy of it. In particular, reflectance spectra provided by the Visible and InfraRed spectrometer (VIR), confirmed that Vesta's mineralogy is dominated by pyroxenes. All Vesta spectra show two strong absorption bands at approx 0.9 and 1.9 micron, typical of the pyroxenes and associated with the howardite, eucrite and diogenite (HED) meteorites.

  13. Image Contrast Enhancement for Brightness Preservation Based on Dynamic Stretching

    Directory of Open Access Journals (Sweden)

    M.A. Rahman

    2015-08-01

    Full Text Available Histogram equalization is an efficient process often employed in consumer electronic systems for image contrast enhancement. In addition to an increase in contrast, it is also required to preserve the mean brightness of an image in order to convey the true scene information to the viewer. A conventional approach is to separate the image into sub-images and then process independently by histogram equalization towards a modified profile. However, due to the variations in image contents, the histogram separation threshold greatly influences the level of shift in mean brightness with respect to the uniform histogram in the equalization process. Therefore, the choice of a proper threshold, to separate the input image into sub-images, is very critical in order to preserve the mean brightness of the output image. In this research work, a dynamic range stretching approach is adopted to reduce the shift in output image mean brightness. Moreover, the computationally efficient golden section search algorithm is applied to obtain a proper separation into sub-images to preserve the mean brightness. Experiments were carried out on a large number of color images of natural scenes. Results, as compared to current available approaches, showed that the proposed method performed satisfactorily in terms of mean brightness preservation and enhancement in image contrast.

  14. Evolution of Bright Screening-photovoltaic Spatial Optical Solitons

    Institute of Scientific and Technical Information of China (English)

    LIU Jinsong

    2001-01-01

    A numerical analysis of the dynamical evolution of bright screening-photovoltaic (SP) spatial solitons in biased photovoltaic-photorefractive materials in the case of neglecting the material loss and the diffusion is presented. When an incident optical beam is a bright SP soliton, the beam propagates along a linear path with its shape kept unchanged. When the incident optical beam is slightly different from a bright SP soliton, the beam reshapes itself and tries to evolve into a bright SP soliton after a short distance. However, when the incident optical beam is significantly different from a SP bright soliton, the beam cannot evolve into a stable bright SP soliton, and tends to experience periodic compression and expansion. For a low-intensity input beam, the wave experiences a periodic process of compression first and then expansion during the initial part of the cycle. For a high-intensity input beam, however, the wave will initially diffract and then experiences compression during the cycle.

  15. A Quantitative Method for Comparing the Brightness of Antibody-dye Reagents and Estimating Antibodies Bound per Cell.

    Science.gov (United States)

    Kantor, Aaron B; Moore, Wayne A; Meehan, Stephen; Parks, David R

    2016-01-01

    We present a quantitative method for comparing the brightness of antibody-dye reagents and estimating antibodies bound per cell. The method is based on complementary binding of test and fill reagents to antibody capture microspheres. Several aliquots of antibody capture beads are stained with varying amounts of the test conjugate. The remaining binding sites on the beads are then filled with a second conjugate containing a different fluorophore. Finally, the fluorescence of the test conjugate compared to the fill conjugate is used to measure the relative brightness of the test conjugate. The fundamental assumption of the test-fill method is that if it takes X molecules of one test antibody to lower the fill signal by Y units, it will take the same X molecules of any other test antibody to give the same effect. We apply a quadratic fit to evaluate the test-fill signal relationship across different amounts of test reagent. If the fit is close to linear, we consider the test reagent to be suitable for quantitative evaluation of antibody binding. To calibrate the antibodies bound per bead, a PE conjugate with 1 PE molecule per antibody is used as a test reagent and the fluorescence scale is calibrated with Quantibrite PE beads. When the fluorescence per antibody molecule has been determined for a particular conjugate, that conjugate can be used for measurement of antibodies bound per cell. This provides comparisons of the brightness of different conjugates when conducted on an instrument whose statistical photoelectron (Spe) scales are known. © 2016 by John Wiley & Sons, Inc.

  16. Bright hybrid white light-emitting quantum dot device with direct charge injection into quantum dot

    Science.gov (United States)

    Cao, Jin; Xie, Jing-Wei; Wei, Xiang; Zhou, Jie; Chen, Chao-Ping; Wang, Zi-Xing; Jhun, Chulgyu

    2016-12-01

    A bright white quantum dot light-emitting device (white-QLED) with 4-[4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl]-2- [3-(tri-phenylen-2-yl)phen-3-yl]quinazoline deposited on a thin film of mixed green/red-QDs as a bilayer emitter is fabricated. The optimized white-QLED exhibits a turn-on voltage of 3.2 V and a maximum brightness of 3660 cd/m2@8 V with the Commission Internationale de l’Eclairage (CIE) chromaticity in the region of white light. The ultra-thin layer of QDs is proved to be critical for the white light generation in the devices. Excitation mechanism in the white-QLEDs is investigated by the detailed analyses of electroluminescence (EL) spectral and the fluorescence lifetime of QDs. The results show that charge injection is a dominant mechanism of excitation in the white-QLED. Project supported by the National Natural Science Foundation of China (Grant No. 21302122) and the Science and Technology Commission of Shanghai Municipality, China (Grant No. 13ZR1416600).

  17. Common fluorescent proteins for single-molecule localization microscopy

    Science.gov (United States)

    Klementieva, Natalia V.; Bozhanova, Nina G.; Mishina, Natalie M.; Zagaynova, Elena V.; Lukyanov, Konstantin A.; Mishin, Alexander S.

    2015-07-01

    Super-resolution techniques for breaking the diffraction barrier are spread out over multiple studies nowadays. Single-molecule localization microscopy such as PALM, STORM, GSDIM, etc allow to get super-resolved images of cell ultrastructure by precise localization of individual fluorescent molecules via their temporal isolation. However, these methods are supposed the use of fluorescent dyes and proteins with special characteristics (photoactivation/photoconversion). At the same time, there is a need for retaining high photostability of fluorophores during long-term acquisition. Here, we first showed the potential of common red fluorescent protein for single-molecule localization microscopy based on spontaneous intrinsic blinking. Also, we assessed the effect of different imaging media on photobleaching of these fluorescent proteins. Monomeric orange and red fluorescent proteins were examined for stochastic switching from a dark state to a bright fluorescent state. We studied fusions with cytoskeletal proteins in NIH/3T3 and HeLa cells. Imaging was performed on the Nikon N-STORM system equipped with EMCCD camera. To define the optimal imaging conditions we tested several types of cell culture media and buffers. As a result, high-resolution images of cytoskeleton structure were obtained. Essentially, low-intensity light was sufficient to initiate the switching of tested red fluorescent protein reducing phototoxicity and provide long-term live-cell imaging.

  18. Ultra-bright and -stable red and near-infrared squaraine fluorophores for in vivo two-photon imaging.

    Science.gov (United States)

    Podgorski, Kaspar; Terpetschnig, Ewald; Klochko, Oleksii P; Obukhova, Olena M; Haas, Kurt

    2012-01-01

    Fluorescent dyes that are bright, stable, small, and biocompatible are needed for high-sensitivity two-photon imaging, but the combination of these traits has been elusive. We identified a class of squaraine derivatives with large two-photon action cross-sections (up to 10,000 GM) at near-infrared wavelengths critical for in vivo imaging. We demonstrate the biocompatibility and stability of a red-emitting squaraine-rotaxane (SeTau-647) by imaging dye-filled neurons in vivo over 5 days, and utility for sensitive subcellular imaging by synthesizing a specific peptide-conjugate label for the synaptic protein PSD-95.

  19. Ultra-bright and -stable red and near-infrared squaraine fluorophores for in vivo two-photon imaging.

    Directory of Open Access Journals (Sweden)

    Kaspar Podgorski

    Full Text Available Fluorescent dyes that are bright, stable, small, and biocompatible are needed for high-sensitivity two-photon imaging, but the combination of these traits has been elusive. We identified a class of squaraine derivatives with large two-photon action cross-sections (up to 10,000 GM at near-infrared wavelengths critical for in vivo imaging. We demonstrate the biocompatibility and stability of a red-emitting squaraine-rotaxane (SeTau-647 by imaging dye-filled neurons in vivo over 5 days, and utility for sensitive subcellular imaging by synthesizing a specific peptide-conjugate label for the synaptic protein PSD-95.

  20. Results of Satellite Brightness Modeling Using Kringing Optimized Interpolation

    Science.gov (United States)

    Weeden, C.; Hejduk, M.

    At the 2005 AMOS conference, Kriging Optimized Interpolation (KOI) was presented as a tool to model satellite brightness as a function of phase angle and solar declination angle (J.M Okada and M.D. Hejduk). Since November 2005, this method has been used to support the tasking algorithm for all optical sensors in the Space Surveillance Network (SSN). The satellite brightness maps generated by the KOI program are compared to each sensor's ability to detect an object as a function of the brightness of the background sky and angular rate of the object. This will determine if the sensor can technically detect an object based on an explicit calculation of the object's probability of detection. In addition, recent upgrades at Ground-Based Electro Optical Deep Space Surveillance Sites (GEODSS) sites have increased the amount and quality of brightness data collected and therefore available for analysis. This in turn has provided enough data to study the modeling process in more detail in order to obtain the most accurate brightness prediction of satellites. Analysis of two years of brightness data gathered from optical sensors and modeled via KOI solutions are outlined in this paper. By comparison, geo-stationary objects (GEO) were tracked less than non-GEO objects but had higher density tracking in phase angle due to artifices of scheduling. A statistically-significant fit to a deterministic model was possible less than half the time in both GEO and non-GEO tracks, showing that a stochastic model must often be used alone to produce brightness results, but such results are nonetheless serviceable. Within the Kriging solution, the exponential variogram model was the most frequently employed in both GEO and non-GEO tracks, indicating that monotonic brightness variation with both phase and solar declination angle is common and testifying to the suitability to the application of regionalized variable theory to this particular problem. Finally, the average nugget value, or

  1. Fluorescence intensity studies of Triassic acritarchs from the Yanchang Formation in Ordos basin,northwestern China

    Institute of Scientific and Technical Information of China (English)

    JI Liming; MENG Fanwei; XU Jinli

    2007-01-01

    Fluorescence properties of Early Cambrian acritarchs were investigated using Leica das Mikroskop (DM)microscopy with a mercury lamp.Well-preserved autoflurescence properties show a correlation between acritarchs morphology and the intensity of emitted fluorescence.In accordance with the fluorescence intensity of organic cell walls,two groups ofmicrofossils were distinguished.Results of observation in this study,which are consistent with those of the previous foreign studies,are in good agreement with regular difference in autofluorescence intensity among palynomorphs reported by McPhilemy (1998).Spores and algae,including Botryococcus,have very bright fluorescence while acritarchs often show less intense fluorescence.Dark brown microfossils have been reworked,and have little or no fluorescence.

  2. Mesangiogenic Progenitor Cells Derived from One Novel CD64brightCD31brightCD14neg Population in Human Adult Bone Marrow

    Science.gov (United States)

    Barachini, Serena; Montali, Marina; Carnicelli, Vittoria; Fazzi, Rita; Parchi, Paolo; Petrini, Mario

    2016-01-01

    Mesenchymal stromal cells (MSCs) have been the object of extensive research for decades, due to their intrinsic clinical value. Nonetheless, the unambiguous identification of a unique in vivo MSC progenitor is still lacking, and the hypothesis that these multipotent cells could possibly arise from different in vivo precursors has been gaining consensus in the last years. We identified a novel multipotent cell population in human adult bone marrow that we first named Mesodermal Progenitor Cells (MPCs) for the ability to differentiate toward the mesenchymal lineage, while still retaining angiogenic potential. Despite extensive characterization, MPCs positioning within the differentiation pathway and whether they can be ascribed as possible distinctive progenitor of the MSC lineage is still unclear. In this study, we describe the ex vivo isolation of one novel bone marrow subpopulation (Pop#8) with the ability to generate MPCs. Multicolor flow cytometry in combination with either fluorescence-activated cell sorting or magnetic-activated cell sorting were applied to characterize Pop#8 as CD64brightCD31brightCD14neg. We defined Pop#8 properties in culture, including the potential of Pop#8-derived MPCs to differentiate into MSCs. Gene expression data were suggestive of Pop#8 in vivo involvement in hematopoietic stem cell niche constitution/maintenance. Pop#8 resulted over three logs more frequent than other putative MSC progenitors, corroborating the idea that most of the controversies regarding culture-expanded MSCs could be the consequence of different culture conditions that select or promote particular subpopulations of precursors. PMID:26975798

  3. Two-photon fluorescence probes for imaging of mitochondria and lysosomes.

    Science.gov (United States)

    Yang, Wanggui; Chan, Pui Shan; Chan, Miu Shan; Li, King Fai; Lo, Pik Kwan; Mak, Nai Ki; Cheah, Kok Wai; Wong, Man Shing

    2013-04-28

    Novel biocompatible cyanines show not only a very large two-photon cross-section of up to 5130 GM at 910 nm in aqueous medium for high-contrast and -brightness two-photon fluorescence live cell imaging but also highly selective subcellular localization properties including localization of mitochondria and lysosomes.

  4. Fluorescent lighting with aluminum nitride phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Srivastava, Alok M.

    2016-05-10

    A fluorescent lamp includes a glass envelope; at least two electrodes connected to the glass envelope; mercury vapor and an inert gas within the glass envelope; and a phosphor within the glass envelope, wherein the phosphor blend includes aluminum nitride. The phosphor may be a wurtzite (hexagonal) crystalline structure Al.sub.(1-x)M.sub.xN phosphor, where M may be drawn from beryllium, magnesium, calcium, strontium, barium, zinc, scandium, yttrium, lanthanum, cerium, praseodymium, europium, gadolinium, terbium, ytterbium, bismuth, manganese, silicon, germanium, tin, boron, or gallium is synthesized to include dopants to control its luminescence under ultraviolet excitation. The disclosed Al.sub.(1-x)M.sub.xN:Mn phosphor provides bright orange-red emission, comparable in efficiency and spectrum to that of the standard orange-red phosphor used in fluorescent lighting, Y.sub.2O.sub.3:Eu. Furthermore, it offers excellent lumen maintenance in a fluorescent lamp, and does not utilize "critical rare earths," minimizing sensitivity to fluctuating market prices for the rare earth elements.

  5. Life-threatening motor vehicle crashes in bright sunlight.

    Science.gov (United States)

    Redelmeier, Donald A; Raza, Sheharyar

    2017-01-01

    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 estimated by evaluating the prevailing weather at the time and place of the crash compared with the weather at the same hour and location on control days a week earlier and a week later.The majority of patients (n = 6962) were injured during daylight hours and bright sunlight was the most common weather condition at the time and place of the crash. The risk of a life-threatening crash was 16% higher during bright sunlight than normal weather (95% confidence interval: 9-24, P vehicle crash. An awareness of this risk might inform driver education, trauma staffing, and safety warnings to prevent a life-threatening motor vehicle crash.

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

    Science.gov (United States)

    Herdiwijaya, Dhani

    2016-11-01

    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.

  7. Night Sky Brightness at San Pedro Martir Observatory

    Science.gov (United States)

    Plauchu-Frayn, I.; Richer, M. G.; Colorado, E.; Herrera, J.; Córdova, A.; Ceseña, U.; Ávila, F.

    2017-03-01

    We present optical UBVRI zenith night sky brightness measurements collected on 18 nights during 2013 to 2016 and SQM measurements obtained daily over 20 months during 2014 to 2016 at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir (OAN-SPM) in México. The UBVRI data is based upon CCD images obtained with the 0.84 m and 2.12 m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 {mag} {{arcsec}}-2, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend implies that the sky has become darker by Δ U = 0.7, Δ B = 0.5, Δ V = 0.3, Δ R=0.5 mag arcsec‑2 since early 2014 due to the present solar cycle.

  8. PROFFIT: Analysis of X-ray surface-brightness profiles

    Science.gov (United States)

    Eckert, Dominique

    2016-08-01

    PROFFIT analyzes X-ray surface-brightness profiles for data from any X-ray instrument. It can extract surface-brightness profiles in circular or elliptical annuli, using constant or logarithmic bin size, from the image centroid, the surface-brightness peak, or any user-given center, and provides surface-brightness profiles in any circular or elliptical sectors. It offers background map support to extract background profiles, can excise areas using SAO DS9-compatible (ascl:0003.002) region files to exclude point sources, provides fitting with a number of built-in models, including the popular beta model, double beta, cusp beta, power law, and projected broken power law, uses chi-squared or C statistic, and can fit on the surface-brightness or counts data. It has a command-line interface similar to HEASOFT’s XSPEC (ascl:9910.005) package, provides interactive help with a description of all the commands, and results can be saved in FITS, ROOT or TXT format.

  9. Night sky brightness at San Pedro Martir Observatory

    CERN Document Server

    Plauchu-Frayn, I; Colorado, E; Herrera, J; Cordova, A; Cesena, U; Avila, F

    2016-01-01

    We present optical UBVRI zenith night sky brightness measurements collected on eighteen nights during 2013--2016 and SQM measurements obtained daily over twenty months during 2014--2016 at the Observatorio Astronomico Nacional on the Sierra San Pedro Martir (OAN-SPM) in Mexico. The UBVRI data is based upon CCD images obtained with the 0.84m and 2.12m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 mag/square arcsec, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend im...

  10. Dark-bright soliton interactions beyond the integrable limit

    Science.gov (United States)

    Katsimiga, G. C.; Stockhofe, J.; Kevrekidis, P. G.; Schmelcher, P.

    2017-01-01

    In this work we present a systematic theoretical analysis regarding dark-bright solitons and their interactions, motivated by recent advances in atomic two-component repulsively interacting Bose-Einstein condensates. In particular, we study analytically via a two-soliton ansatz adopted within a variational formulation the interaction between two dark-bright solitons in a homogeneous environment beyond the integrable regime, by considering general inter- and intra-atomic interaction coefficients. We retrieve the possibility of a fixed point in the case where the bright solitons are out of phase. As the intercomponent interaction is increased, we also identify an exponential instability of the two-soliton state, associated with a subcritical pitchfork bifurcation. The latter gives rise to an asymmetric partition of the bright soliton mass and dynamically leads to spontaneous splitting of the bound pair. In the case of the in-phase bright solitons, we explain via parsing the analytical approximations and monitoring the direct dynamics why no such pair is identified, despite its prediction by the variational analysis.

  11. Microwave heating of arginine yields highly fluorescent nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Philippidis, Aggelos [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser (Greece); Stefanakis, Dimitrios [University of Crete, Department of Chemistry (Greece); Anglos, Demetrios, E-mail: anglos@iesl.forth.gr [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser (Greece); Ghanotakis, Demetrios, E-mail: ghanotakis@chemistry.uoc.gr [University of Crete, Department of Chemistry (Greece)

    2013-01-15

    Brightly fluorescent nanoparticles were produced via a single-step, single-precursor procedure based on microwave heating of an aqueous solution of the amino acid arginine. Key structural and optical properties of the resulting Arg nanoparticles, Arg-dots, are reported and discussed with emphasis on the pH dependence of their fluorescence emission. The surface of the Arg-dots was functionalised through coupling to folic acid, opening up ways for connecting fluorescent nanoparticles to cancer cells. The generality and versatility of the microwave heating procedure was further demonstrated by the synthesis of different types of carbon nanoparticles, such as CE-dots, that were produced by use of citric acid and ethanolamine as precursors and compared to the Arg-dots.

  12. Nanocomposite plasmonic fluorescence emitters with core/shell configurations

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Xiaoyu; Brener, Igal; Luk, Ting Shan

    2010-07-16

    This paper is focused on the optical properties of nanocomposite plasmonic emitters with core/shell configurations, where a fluorescence emitter is located inside a metal nanoshell. Systematic theoretical investigations are presented for the influence of material type, core radius, shell thickness, and excitation wavelength on the internal optical intensity, radiative quantum yield, and fluorescence enhancement of the nanocomposite emitter. It is our conclusion that: (i) an optimal ratio between the core radius and shell thickness is required to maximize the absorption rate of fluorescence emitters, and (ii) a large core radius is desired to minimize the non-radiative damping and avoid significant quantum yield degradation of light emitters. Several experimental approaches to synthesize these nanocomposite emitters are also discussed. Furthermore, our theoretical results are successfully used to explain several reported experimental observations and should prove useful for designing ultra-bright core/shell nanocomposite emitters.

  13. Nanocomposite plasmonic fluorescence emitters with core/shell configurations.

    Energy Technology Data Exchange (ETDEWEB)

    Brener, Igal; Luk, Ting Shan; Miao, Xiaoyu

    2010-06-01

    This paper is focused on the optical properties of nanocomposite plasmonic emitters with core/shell configurations, where a fluorescence emitter is located inside a metal nanoshell. Systematic theoretical investigations are presented for the influence of material type, core radius, shell thickness, and excitation wavelength on the internal optical intensity, radiative quantum yield, and fluorescence enhancement of the nanocomposite emitter. It is our conclusion that: (i) an optimal ratio between the core radius and shell thickness is required to maximize the absorption rate of fluorescence emitters, and (ii) a large core radius is desired to minimize the non-radiative damping and avoid significant quantum yield degradation of light emitters. Several experimental approaches to synthesize these nanocomposite emitters are also discussed. Furthermore, our theoretical results are successfully used to explain several reported experimental observations and should prove useful for designing ultra-bright core/shell nanocomposite emitters.

  14. Giant Amplification of Photoswitching by a Few Photons in Fluorescent Photochromic Organic Nanoparticles.

    Science.gov (United States)

    Su, Jia; Fukaminato, Tuyoshi; Placial, Jean-Pierre; Onodera, Tsunenobu; Suzuki, Ryuju; Oikawa, Hidetoshi; Brosseau, Arnaud; Brisset, François; Pansu, Robert; Nakatani, Keitaro; Métivier, Rémi

    2016-03-07

    Controlling or switching the optical signal from a large collection of molecules with the minimum of photons represents an extremely attractive concept. Promising fundamental and practical applications may be derived from such a photon-saving principle. With this aim in mind, we have prepared fluorescent photochromic organic nanoparticles (NPs), showing bright red emission, complete ON-OFF contrast with full reversibility, and excellent fatigue resistance. Most interestingly, upon successive UV and visible light irradiation, the NPs exhibit a complete fluorescence quenching and recovery at very low photochromic conversion levels (photochromic molecule. This "giant amplification of fluorescence photoswitching" originates from efficient intermolecular energy-transfer processes within the NPs.

  15. Fluorescence fluctuation spectroscopy: ushering in a new age of enlightenment for cellular dynamics.

    Science.gov (United States)

    Jameson, David M; Ross, Justin A; Albanesi, Joseph P

    2009-09-01

    Originally developed for applications in physics and physical chemistry, fluorescence fluctuation spectroscopy is becoming widely used in cell biology. This review traces the development of the method and describes some of the more important applications. Specifically, the methods discussed include fluorescence correlation spectroscopy (FCS), scanning FCS, dual color cross-correlation FCS, the photon counting histogram and fluorescence intensity distribution analysis approaches, the raster scanning image correlation spectroscopy method, and the Number and Brightness technique. The physical principles underlying these approaches will be delineated, and each of the methods will be illustrated using examples from the literature.

  16. The Spectroscopic Properties of Bright Extragalactic Planetary Nebulae

    CERN Document Server

    Richer, M G

    2006-01-01

    The properties of bright extragalactic planetary nebulae are reviewed based upon the results of low and high resolution spectroscopy. It is argued that bright extragalactic planetary nebulae from galaxies (or subsystems) with and without star formation have different distributions of central star temperature and ionization structure. As regards the chemical compositions, oxygen and neon are generally found to be unchanged as a result of the evolution of the stellar progenitors. Nitrogen enrichment may occur as a result of the evolution of the progenitors of bright planetary nebulae in all stellar populations, though this enrichment may be (more) random in old stellar populations. Helium abundances appear to be influenced by the chemical evolution of the host galaxy, with planetary nebulae in dwarf spheroidals having systematically elevated abundances. Neither the age nor the metallicity of the progenitor stellar population has a strong effect upon the kinematics observed for nebular shells. Both the range of ...

  17. Dark-bright ring solitons in Bose-Einstein condensates

    Energy Technology Data Exchange (ETDEWEB)

    Stockhofe, J; Schmelcher, P [Zentrum fuer Optische Quantentechnologien, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Kevrekidis, P G [Department of Mathematics and Statistics, University of Massachusetts, Amherst MA 01003-4515 (United States); Frantzeskakis, D J, E-mail: jstockho@physnet.uni-hamburg.de, E-mail: kevrekid@math.umass.edu [Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens 157 84 (Greece)

    2011-10-14

    We study dark-bright (DB) ring solitons in two-component Bose-Einstein condensates. In the limit of large densities of the dark component, we describe the soliton dynamics by means of an equation of motion for the ring radius. The presence of the bright, 'filling' species is demonstrated to have a stabilizing effect on the ring dark soliton. Near the linear limit, we discuss the symmetry-breaking bifurcations of DB soliton stripes and vortex-bright soliton clusters from the DB ring and relate the stabilizing effect of filling to changes in the bifurcation diagram. Finally, we show that the stabilization by means of a second component is not limited to the radially symmetric structures, but can also be observed in a cross-like DB soliton configuration. (fast track communication)

  18. 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

  19. The ASAS-SN Bright Supernova Catalog $-$ II. 2015

    CERN Document Server

    Holoien, T W -S; Stanek, K Z; Kochanek, C S; Shappee, B J; Prieto, J L; Dong, Subo; Brimacombe, J; Bishop, D W; Basu, U; Beacom, J F; Bersier, D; Chen, Ping; Danilet, A B; Falco, E; Godoy-Rivera, D; Goss, N; Pojmanski, G; Simonian, G V; Skowron, D M; Thompson, Todd A; Woźniak, P R; Avíla, C G; Bock, G; Carballo, J -L G; Conseil, E; Contreras, C; Cruz, I; andújar, J M F; Guo, Zhen; Hsiao, E Y; Kiyota, S; Koff, R A; Krannich, G; Madore, B F; Marples, P; Masi, G; Morrell, N; Monard, L A G; Munoz-Mateos, J C; Nicholls, B; Nicolas, J; Wagner, R M; Wiethoff, W S

    2016-01-01

    This manuscript presents information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) during 2015, its second full year of operations. The same information is presented for bright ($m_V\\leq17$), spectroscopically confirmed supernovae discovered by other sources in 2015. As with the first ASAS-SN bright supernova catalog, we also present redshifts and near-UV through IR magnitudes for all supernova host galaxies in both samples. Combined with our previous catalog, this work comprises a complete catalog of 455 supernovae from multiple professional and amateur sources, allowing for population studies that were previously impossible. This is the second of a series of yearly papers on bright supernovae and their hosts from the ASAS-SN team.

  20. High-brightness ultra-cold metastable neon-beam

    CERN Document Server

    Shimizu, Fujio

    2015-01-01

    This paper presents detailed characteristics of an ultra-cold bright metastable neon atomic beam which we have been using for atom-interferometric applications. The basis of the device is an atomic beam released from a magneto-optical trap (MOT) which is operated with a high intensity trapping laser, high magnetic quadrupole field, and large laser detuining. Mainly due to the complex structure of three dimensional magnetic field and laser beams, a bright small spot of atoms is formed near the center of the quadrupole magnetic field under an appropriate operating condition. We obtained the minimum trap diameter of 50 micron meter, the atomic density nearly 10^{13}cm^{-3}, and the atomic temperature slightly less than the Doppler limited temperature of 200 micro-K. By releasing trapped atoms we obtained an bright cold atomic beam which is not far from the collision limited atomic density.

  1. New low surface brightness dwarf galaxies detected around nearby spirals

    Science.gov (United States)

    Karachentsev, I. D.; Riepe, P.; Zilch, T.; Blauensteiner, M.; Elvov, M.; Hochleitner, P.; Hubl, B.; Kerschhuber, G.; Küppers, S.; Neyer, F.; Pölzl, R.; Remmel, P.; Schneider, O.; Sparenberg, R.; Trulson, U.; Willems, G.; Ziegler, H.

    2015-10-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their absolute magnitudes are in the range of -8.6 > M B > -13.3, their effective diameters are 0.4-4.7 kpc, and the average surface brightness is 26ṃ1/□″. The mean linear projected separation of the satellite candidates from the host galaxies is 73 kpc. Our spectroscopic observations of two LSB dwarfs with the Russian 6-meter telescope confirm their physical connection to the host galaxies NGC891 and NGC2683.

  2. Automated Detection and Tracking of Solar Magnetic Bright Points

    CERN Document Server

    Crockett, P J; Mathioudakis, M; Keenan, F P

    2009-01-01

    Magnetic Bright Points (MBPs) in the internetwork are among the smallest objects in the solar photosphere and appear bright against the ambient environment. An algorithm is presented that can be used for the automated detection of the MBPs in the spatial and temporal domains. The algorithm works by mapping the lanes through intensity thresholding. A compass search, combined with a study of the intensity gradient across the detected objects, allows the disentanglement of MBPs from bright pixels within the granules. Object growing is implemented to account for any pixels that might have been removed when mapping the lanes. The images are stabilized by locating long-lived objects that may have been missed due to variable light levels and seeing quality. Tests of the algorithm employing data taken with the Swedish Solar Telescope (SST), reveal that ~90% of MBPs within a 75"x 75" field of view are detected.

  3. RF Manipulations for Higher Brightness LHC-Type Beams

    CERN Document Server

    Damerau, H; Gilardoni, S; Hancock, S

    2013-01-01

    In order to increase the transverse brightness of beams for the LHC, ever more complicated RF manipulations have been proposed in the PS machine to reduce the intensity demands per PS batch on the upstream PS Booster. Several schemes based on cascades of batch compression, bunch merging, as well as the more routine bunch splitting have been successfully commissioned and higher brightness beams have been delivered to the downstream accelerators for measurement. Despite all this complexity, longitudinal and transverse beam quality are well preserved. In addition, to profit fully from the brightness of all four PS Booster rings, the injection of twice 4 bunches into harmonic 9 buckets in the PS has been made operational as an alternative to the usual double-batch transfer of 4 + 2 bunches into harmonic 7. This paper summarizes the new beam production schemes, their implementation in the PS low-level RF system and the experimental results..

  4. New Low Surface Brightness Dwarf Galaxies Detected Around Nearby Spirals

    CERN Document Server

    Karachentsev, I D; Zilch, T; Blauensteiner, M; Elvov, M; Hochleitner, P; Hubl, B; Kerschhuber, G; Küppers, S; Neyer, F; Pölzl, R; Remmel, P; Schneider, O; Sparenberg, R; Trulson, U; Willems, G; Ziegler, H

    2015-01-01

    We conduct a survey of low surface brightness (LSB) satellite galaxies around the Local Volume massive spirals using long exposures with small amateur telescopes. We identified 27 low and very low surface brightness objects around the galaxies NGC,672, 891, 1156, 2683, 3344, 4258, 4618, 4631, and 5457 situated within 10 Mpc from us, and found nothing new around NGC,2903, 3239, 4214, and 5585. Assuming that the dwarf candidates are the satellites of the neighboring luminous galaxies, their absolute magnitudes are in the range of -8.6 > M_B > -13.3, their effective diameters are 0.4-4.7 kpc, and the average surface brightness is 26.1 mag/sq arcsec. The mean linear projected separation of the satellite candidates from the host galaxies is 73 kpc. Our spectroscopic observations of two LSB dwarfs with the Russian 6-meter telescope confirm their physical connection to the host galaxies NGC,891 and NGC,2683.

  5. The ASAS-SN Bright Supernova Catalog - II. 2015

    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.; Basu, U.; Beacom, J. F.; Bersier, D.; Chen, Ping; Danilet, A. B.; Falco, E.; Godoy-Rivera, D.; Goss, N.; Pojmanski, G.; Simonian, G. V.; Skowron, D. M.; Thompson, Todd A.; Woźniak, P. R.; Ávila, C. G.; Bock, G.; Carballo, J.-L. G.; Conseil, E.; Contreras, C.; Cruz, I.; Andújar, J. M. F.; Guo, Zhen; Hsiao, E. Y.; Kiyota, S.; Koff, R. A.; Krannich, G.; Madore, B. F.; Marples, P.; Masi, G.; Morrell, N.; Monard, L. A. G.; Munoz-Mateos, J. C.; Nicholls, B.; Nicolas, J.; Wagner, R. M.; Wiethoff, W. S.

    2017-01-01

    This manuscript presents information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) during 2015, its second full year of operations. The same information is presented for bright (mV ≤ 17), spectroscopically confirmed supernovae discovered by other sources in 2015. As with the first ASAS-SN bright supernova catalog, we also present redshifts and near-UV through IR magnitudes for all supernova host galaxies in both samples. Combined with our previous catalog, this work comprises a complete catalog of 455 supernovae from multiple professional and amateur sources, allowing for population studies that were previously impossible. This is the second of a series of yearly papers on bright supernovae and their hosts from the ASAS-SN team.

  6. Highly indistinguishable on-demand resonance fluorescence photons from a deterministic quantum dot micropillar device with 74% extraction efficiency

    DEFF Research Database (Denmark)

    Gregersen, Niels

    2016-01-01

    device is a major challenge. Here, we report on the observation of bright single photon emission generated via pulsed, resonance fluorescence conditions from a single quantum dot (QD) deterministically centered in a micropillar cavity device via cryogenic optical lithography. The brightness of the QD...... fluorescence is greatly enhanced on resonance with the fundamental mode of the pillar, leading to an overall device efficiency of η = (74 ± 4) % for a single photon emission as pure as g (2) (0) = 0.0092 ± 0.0004. The combination of large Purcell enhancement and resonant pumping conditions allows us to observe...... a two-photon wave packet overlap up to ν = (88±3) %....

  7. Life-threatening motor vehicle crashes in bright sunlight

    Science.gov (United States)

    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 estimated by evaluating the prevailing weather at the time and place of the crash compared with the weather at the same hour and location on control days a week earlier and a week later. The majority of patients (n = 6962) were injured during daylight hours and bright sunlight was the most common weather condition at the time and place of the crash. The risk of a life-threatening crash was 16% higher during bright sunlight than normal weather (95% confidence interval: 9–24, P < 0.001). The increased risk was accentuated in the early afternoon, disappeared at night, extended to patients with different characteristics, involved crashes with diverse features, not apparent with cloudy weather, and contributed to about 5000 additional patient-days in hospital. The increased risk extended to patients with high crash severity as indicated by ambulance involvement, surgical procedures, length of hospital stay, intensive care unit admission, and patient mortality. The increased risk was not easily attributed to differences in alcohol consumption, driving distances, or anomalies of adverse weather. Bright sunlight is associated with an increased risk of a life-threatening motor vehicle crash. An awareness of this risk might inform driver education, trauma staffing, and safety warnings to prevent a life-threatening motor vehicle crash. Level of evidence: Epidemiologic Study, level III. PMID:28072708

  8. Effects of Bright Light Treatment on Psychomotor Speed in Athletes

    Directory of Open Access Journals (Sweden)

    Mikko Paavo Tulppo

    2014-05-01

    Full Text Available Purpose: A recent study suggests that transcranial brain targeted light treatment via ear canals may have physiological effects on brain function studied by functional magnetic resonance imaging (fMRI techniques in humans. We tested the hypothesis that bright light treatment could improve psychomotor speed in professional ice hockey players. Methods: Psychomotor speed tests with audio and visual warning signals were administered to a Finnish National Ice Hockey League team before and after 24 days of transcranial bright light or sham treatment. The treatments were given during seasonal darkness in the Oulu region (latitude 65 degrees north when the strain on the players was also very high (10 matches during 24 days. A daily 12-min dose of bright light or sham (n = 11 for both treatment was given every morning between 8–12 am at home with a transcranial bright light device. Mean reaction time and motor time were analyzed separately for both psychomotor tests. Analysis of variance for repeated measures adjusted for age was performed. Results: Time x group interaction for motor time with a visual warning signal was p = 0.024 after adjustment for age. In Bonferroni post-hoc analysis, motor time with a visual warning signal decreased in the bright light treatment group from 127 ± 43 to 94 ± 26 ms (p = 0.024 but did not change significantly in the sham group 121 ± 23 vs. 110 ± 32 ms (p = 0.308. Reaction time with a visual signal did not change in either group. Reaction or motor time with an audio warning signal did not change in either the treatment or sham group. Conclusion: Psychomotor speed, particularly motor time with a visual warning signal, improves after transcranial bright light treatment in professional ice-hockey players during the competition season in the dark time of the year.

  9. The possible origin of facular brightness in the solar atmosphere

    Science.gov (United States)

    Kostik, R.; Khomenko, E.

    2016-05-01

    This paper studies the dependence of the Ca ii H line core brightness on the strength and inclination of the photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the center of the solar disc. We use three simultaneous data sets that were obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of Ba ii 4554 Å line, registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in Fe i 1.56 μm lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in Ca ii H that give information about brightness fluctuations in the chromosphere. The results show that the Ca ii H brightness in the facula strongly depends on the power of waves with periods in the 5-min range, which propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature minimum height that is measured from Ba ii line. The Ca ii H brightness is maximum at locations where the phase shift between temperature and velocity oscillations lies within 0°-100°. There is an indirect influence of convective motions on the Ca ii H brightness. The higher the amplitude of convective velocities is and the greater the height is where they change their direction of motion, the brighter the facula. In summary, our results lead to conclusions that facular regions appear bright not only because of the Wilson depression in magnetic structures, but also owing to real heating.

  10. Bright and dark excitons in semiconductor carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Tretiak, Sergei [Los Alamos National Laboratory

    2008-01-01

    We report electronic structure calculations of finite-length semiconducting carbon nanotubes using the time dependent density functional theory (TD-DFT) and the time dependent Hartree Fock (TD-HF) approach coupled with semiempirical AM1 and ZINDO Hamiltonians. We specifically focus on the energy splitting, relative ordering, and localization properties of the optically active (bright) and optically forbidden (dark) states from the lowest excitonic band of the nanotubes. These excitonic states are very important in competing radiative and non-radiative processes in these systems. Our analysis of excitonic transition density matrices demonstrates that pure DFT functionals overdelocalize excitons making an electron-hole pair unbound; consequently, excitonic features are not presented in this method. In contrast, the pure HF and A111 calculations overbind excitons inaccurately predicting the lowest energy state as a bright exciton. Changing AM1 with ZINDO Hamiltonian in TD-HF calculations, predicts the bright exciton as the second state after the dark one. However, in contrast to AM1 calculations, the diameter dependence of the excitation energies obtained by ZINDO does not follow the experimental trends. Finally, the TD-DFT approach incorporating hybrid functions with a moderate portion of the long-range HF exchange, such as B3LYP, has the most generality and predictive capacity providing a sufficiently accurate description of excitonic structure in finite-size nanotubes. These methods characterize four important lower exciton bands. The lowest state is dark, the upper band is bright, and the two other dark and nearly degenerate excitons lie in-between. Although the calculated energy splittings between the lowest dark and the bright excitons are relatively large ({approx}0.1 eV), the dense excitonic manifold below the bright exciton allows for fast non-radiative relaxation leasing to the fast population of the lowest dark exciton. This rationalizes the low

  11. Fluorescence antibunching microscopy

    CERN Document Server

    Schwartz, Osip

    2011-01-01

    Breaking the diffraction limit in microscopy by utilizing quantum properties of light has been the goal of intense research in the recent years. We propose a quantum superresolution technique based on non-classical emission statistics of fluorescent markers, routinely used as contrast labels for bio-imaging. The technique can be readily implemented using standard fluorescence microscopy equipment.

  12. LEDs for fluorescence microscopy

    NARCIS (Netherlands)

    Young, I.T.; Garini, Y.; Dietrich, H.R.C.; Van Oel, W.; Liqui Lung, G.

    2004-01-01

    Traditional light sources for fluorescence microscopy have been mercury lamps, xenon lamps, and lasers. These sources have been essential in the development of fluorescence microscopy but each can have serious disadvantages: lack of near monochromaticity, heat generation, cost, lifetime of the light

  13. Fluorescence of atopic allergens

    NARCIS (Netherlands)

    Berrens, L.

    1967-01-01

    Purified atopic allergens have been found to emit flue fluorescence upon irradiation with ultraviolet light of 365 mμ wavelength. The maximum of fluorescence is in the region 445–490 mμ and the intensity is of the same order of magnitude for different atopic allergens. Synthetic model compounds, inc

  14. A green fluorescent protein with photoswitchable emission from the deep sea.

    Directory of Open Access Journals (Sweden)

    Alexander Vogt

    Full Text Available A colorful variety of fluorescent proteins (FPs from marine invertebrates are utilized as genetically encoded markers for live cell imaging. The increased demand for advanced imaging techniques drives a continuous search for FPs with new and improved properties. Many useful FPs have been isolated from species adapted to sun-flooded habitats such as tropical coral reefs. It has yet remained unknown if species expressing green fluorescent protein (GFP-like proteins also exist in the darkness of the deep sea. Using a submarine-based and -operated fluorescence detection system in the Gulf of Mexico, we discovered ceriantharians emitting bright green fluorescence in depths between 500 and 600 m and identified a GFP, named cerFP505, with bright fluorescence emission peaking at 505 nm. Spectroscopic studies showed that approximately 15% of the protein bulk feature reversible ON/OFF photoswitching that can be induced by alternating irradiation with blue und near-UV light. Despite being derived from an animal adapted to essentially complete darkness and low temperatures, cerFP505 maturation in living mammalian cells at 37 degrees C, its brightness and photostability are comparable to those of EGFP and cmFP512 from shallow water species. Therefore, our findings disclose the deep sea as a potential source of GFP-like molecular marker proteins.

  15. The brightness variations of Comet Halley at large heliocentric distances

    Science.gov (United States)

    Flammer, K. R.; Jackson, B.; Houpis, H. L. F.; Mendis, D. A.

    1986-01-01

    The reasons for the intrinsic brightness variations of up to 500 percent on time scales as short as a few hours detected by Sekanina (1984) in Comet Halley between October 1982 and February 1984 are discussed. It is shown that solar wind-modulated electrostatic dust blowoff from the night side of the comet is consistent with the observed brightness variations. The variations coincide with the encounter of high-speed streams with the comet. The stream's propagation time to the comet and the sun's rotation during this transit were used to locate the stream origin on the coronal surface, and the results are shown.

  16. Do low surface brightness galaxies have dense disks?

    CERN Document Server

    Saburova, A S

    2010-01-01

    The disk masses of four low surface brightness galaxies (LSB) were estimated using marginal gravitational stability criterion and the stellar velocity dispersion data which were taken from Pizzella et al., 2008 [1]. The constructed mass models appear to be close to the models of maximal disk. The results show that the disks of LSB galaxies may be significantly more massive than it is usually accepted from their brightnesses. In this case their surface densities and masses appear to be rather typical for normal spirals. Otherwise, unlike the disks of many spiral galaxies, the LSB disks are dynamically overheated.

  17. Laser ion source for high brightness heavy ion beam

    Science.gov (United States)

    Okamura, M.

    2016-09-01

    A laser ion source is known as a high current high charge state heavy ion source. However we place great emphasis on the capability to realize a high brightness ion source. A laser ion source has a pinpoint small volume where materials are ionized and can achieve quite uniform low temperature ion beam. Those features may enable us to realize very small emittance beams. In 2014, a low charge state high brightness laser ion source was successfully commissioned in Brookhaven National Laboratory. Now most of all the solid based heavy ions are being provided from the laser ion source for regular operation.

  18. Influence of Type of Electric Bright Light on the Attraction of the African Giant Water Bug, Lethocerus indicus (Hemiptera: Belostomatidae

    Directory of Open Access Journals (Sweden)

    Luke Chinaru Nwosu

    2012-01-01

    Full Text Available This study investigated the influence of type of electric bright light (produced by fluorescent light tube and incandescent light bulb on the attraction of the African giant water bug, Lethocerus indicus (Hemiptera: Belostomatidae. Four fluorescent light tubes of 15 watts each, producing white-coloured light and four incandescent light bulbs of 60 watts each, producing yellow-coloured light, but both producing the same amount of light, were varied and used for the experiments. Collections of bugs at experimental house were done at night between the hours of 8.30 pm and 12 mid-night on daily basis for a period of four months per experiment in the years 2008 and 2009. Lethocerus indicus whose presence in any environment has certain implications was the predominant belostomatid bug in the area. Use of incandescent light bulbs in 2009 significantly attracted more Lethocerus indicus 103 (74.6% than use of fluorescent light tubes 35 (25.41% in 2008 [4.92=0.0001]. However, bug’s attraction to light source was not found sex dependent [>0.05; (>0.18=0.4286 and >0.28=0.3897]. Therefore, this study recommends the use of fluorescent light by households, campgrounds, and other recreational centres that are potentially exposed to the nuisance of the giant water bugs. Otherwise, incandescent light bulbs should be used when it is desired to attract the presence of these aquatic bugs either for food or scientific studies.

  19. Tb{sup 3+} doped Zinc Alumino Bismuth Borate glasses for green emitting luminescent devices

    Energy Technology Data Exchange (ETDEWEB)

    Swapna, K.; Mahamuda, Sk. [Department of Physics, K L University, Green Fields, Vaddeswaram, Guntur (Dt), Andhra Pradesh 522502 (India); Rao, A. Srinivasa, E-mail: drsrallam@gmail.com [Department of Physics, K L University, Green Fields, Vaddeswaram, Guntur (Dt), Andhra Pradesh 522502 (India); Department of Applied Physics, Delhi Technological University, Bawana Road, New Delhi 110042 (India); Jayasimhadri, M. [Department of Applied Physics, Delhi Technological University, Bawana Road, New Delhi 110042 (India); Shakya, Suman; Prakash, G. Vijaya [Nanophotonics Laboratory, Department of Physics, Indian Institute of Technology-Delhi, Hauz Khas, New Delhi 110016 (India)

    2014-12-15

    Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with terbium (Tb{sup 3+}) ions with a chemical composition 20ZnO–10Al{sub 2}O{sub 3}–(10−x)Bi{sub 2}O{sub 3}–60B{sub 2}O{sub 3}−xTb{sub 2}O{sub 3} (x=0.1, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mol%) were prepared by a conventional melt quenching method and studied their optical absorption, photoluminescence and decay spectral properties. The Judd–Ofelt (J–O) parameters evaluated from the experimental oscillator strengths were used to measure the radiative properties for the prominent luminescent transitions of Tb{sup 3+} ions such as {sup 5}D{sub 4}→{sup 7}F{sub 6}, {sup 7}F{sub 5}, {sup 7}F{sub 4} and {sup 7}F{sub 3.} The effect of Tb{sup 3+} ion concentration on the luminescence process observed in the visible region was discussed in detail. The emission spectra recorded for all the ZnAlBiB glasses doped with Tb{sup 3+} ions, show an intense peak in green region at 542 nm. The stimulated emission cross-section, branching ratios and quantum efficiency values evaluated for green emission ({sup 5}D{sub 4}→{sup 7}F{sub 5}) suggests the utility of these glasses for green luminescence applications. It was found that, within the concentration range investigated, 2.5 mol% of Tb{sup 3+} doped ZnAlBiB glass is most suitable for green luminescence applications at 542 nm in principle. - Highlights: • ZnAlBiB glasses doped with Tb{sup 3+} ions were prepared by a conventional melt quenching technique. • Judd–Ofelt and radiative properties are measured from the emission spectra. • Quantum efficiency of the ZnAlBiB glasses is measured by using radiative and measured lifetimes. • CIE Chromaticity co-ordinates are evaluated from emission spectra.

  20. A green emitting phosphorescent copper(I) complex with tetrazole derived ligand for electroluminescence application.

    Science.gov (United States)

    Tong, Senmiao; Yuan, Donglin; Yi, Lita

    2014-09-15

    In this paper, a tetrazole derived diamine ligand of 2-(1H-tetrazol-5-yl)pyridine (TP) owing electron-donors and short conjugation chain was synthesized to increase the band gap of its corresponding phosphorescent Cu(I) complex. This Cu(I) complex was characterized in detail, including its single crystal structure, singlet electronic transitions, photophysical parameters, thermal stability and electrochemical property. Upon on photoexcitation, this Cu(I) complex emitted green emission peaking at 497 nm with biexponential decay pattern of τ1=5.5414 μs (A1=0.137) and τ2=1.0679 μs (A2=0.11503). Cyclic voltammerty experiment suggested that this Cu(I) complex owned HOMO and LUMO energy levels of -5.79 eV and -2.39 eV. The thermal decomposition temperature was 170°C as indicated by thermogravimetric analysis. The optimal electroluminescence device constructed by solution processed coating procedure showed green electroluminescence peaking at 525 nm, with maximum luminance of 2860 cd/m2 and maximum current efficiency of 5.9 cd/A.

  1. Luminescence studies on green emitting InGaN/GaN MQWs implanted with nitrogen

    OpenAIRE

    2015-01-01

    We studied the optical properties of metalorganic chemical vapour deposited (MOCVD) InGaN/GaN multiple quantum wells (MQW) subjected to nitrogen (N) implantation and post-growth annealing treatments. The optical characterization was carried out by means of temperature and excitation density-dependent steady state photoluminescence (PL) spectroscopy, supplemented by room temperature PL excitation (PLE) and PL lifetime (PLL) measurements. The as-grown and as-implanted samples were found to exhi...

  2. Fluorescence and Spectral Imaging

    Directory of Open Access Journals (Sweden)

    Ralph S. DaCosta

    2007-01-01

    Full Text Available Early identification of dysplasia remains a critical goal for diagnostic endoscopy since early discovery directly improves patient survival because it allows endoscopic or surgical intervention with disease localized without lymph node involvement. Clinical studies have successfully used tissue autofluorescence with conventional white light endoscopy and biopsy for detecting adenomatous colonic polyps, differentiating benign hyperplastic from adenomas with acceptable sensitivity and specificity. In Barrett's esophagus, the detection of dysplasia remains problematic because of background inflammation, whereas in the squamous esophagus, autofluorescence imaging appears to be more dependable. Point fluorescence spectroscopy, although playing a crucial role in the pioneering mechanistic development of fluorescence endoscopic imaging, does not seem to have a current function in endoscopy because of its nontargeted sampling and suboptimal sensitivity and specificity. Other point spectroscopic modalities, such as Raman spectroscopy and elastic light scattering, continue to be evaluated in clinical studies, but still suffer the significant disadvantages of being random and nonimaging. A recent addition to the fluorescence endoscopic imaging arsenal is the use of confocal fluorescence endomicroscopy, which provides real-time optical biopsy for the first time. To improve detection of dysplasia in the gastrointestinal tract, a new and exciting development has been the use of exogenous fluorescence contrast probes that specifically target a variety of disease-related cellular biomarkers using conventional fluorescent dyes and novel potent fluorescent nanocrystals (i.e., quantum dots. This is an area of great promise, but still in its infancy, and preclinical studies are currently under way.

  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...

  4. Bright infrared LEDs based on colloidal quantum-dots

    KAUST Repository

    Sun, Liangfeng

    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.

  5. The HI dominated Low Surface Brightness Galaxy KKR17

    CERN Document Server

    Lam, Man I; Yang, Ming; Zhou, Zhi-Min; Du, Wei; Zhu, Yi-Nan

    2014-01-01

    We present new narrow-band (H$\\alpha$ and [OIII]) imagings and optical spectrophotometry of HII regions for a gas-rich low surface brightness irregular galaxy, KKR 17. The central surface brightness of the galaxy is $\\mu_0(B)$ = 24.15 $\\pm$0.03 mag~sec$^{-2}$. The galaxy was detected by \\emph{Arecibo Legacy Fast ALFA survey} (ALFALFA), and its mass is dominated by neutral hydrogen (HI) gas. In contrast, both the stellar masses of the bright HII and diffuse stellar regions are small. In addition, the fit to the spectral energy distribution to each region shows the stellar populations of HII and diffuse regions are different. The bright HII region contains a large fraction of O-type stars, revealing the recent strong star formation, whereas the diffuse region is dominated by median age stars, which has a typical age of $\\sim$ 600 Myrs. Using the McGaugh's abundance model, we found that the average metallicity of KKR 17 is 12 + (O/H) = 8.0 $\\pm$ 0.1. The star formation rate of KKR 17 is 0.21$\\pm$0.04 M$_{\\odot}$...

  6. The scroll of Pure Brightness on the River

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    <正>The scroll of Pure Brightness on the River drawn by the Chinese tradi tional painting master Zeduan Zhang depicts a well-off scene of Dongjing (present city of Kaifeng), which was the capital of the Northern Song dynasty a thousand year ago and was the top-ranking metropolis at that time. The scroll

  7. Does bright light have an anxiolytic effect? - an open trial

    Directory of Open Access Journals (Sweden)

    Kripke Daniel F

    2007-10-01

    Full Text Available Abstract Background The aim of this open trial was to examine the influence of acute bright light exposure on anxiety in older and young adults. Methods This study was ancillary to a complex 5-day laboratory experiment testing phase-responses to light at all times of the day. On 3 consecutive days, participants were exposed to bright light (3,000 lux for 3 hours. The Spielberger State-Trait Anxiety Inventory (Form Y1 was administered 5 minutes before and 20 minutes after each treatment. Mean state anxiety before and after treatment were analyzed by age, sex, and time ANOVA. To avoid floor effects, only participants with baseline STAI levels of ≥ 25 were included. Results A significant anxiolytic effect of bright light was found for the mean data, as well as for each of the three days. No significant main effect of age, sex, or interaction of these factors with STAI change were found. Conclusion The results show consistent and significant (albeit modest anxiolytic effects following acute bright light exposure in low anxiety adults. Further randomized, controlled trials in clinically anxious individuals are needed.

  8. Two Cataclysmic Variables Identified from ROSAT Bright Sources

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents the results of optical spectroscopic observations of two ROSAT bright sources, 1RXS J020928.9+283243 and 1RXS J042332.8+745300. The low-dispersion spectra suggest the cataclysmic variable classification for the two objects. Further photometric observations are expected to reveal the variable features and to confirm the classifications.

  9. Star Formation Rates in Low Surface Brightness Galaxies

    NARCIS (Netherlands)

    Pickering, T. E.; Impey, C. D.; van Gorkom, J.; Bothun, G. D.

    1994-01-01

    The low surface brightness (LSB) disk galaxies found in recent surveys (e.g.,\\ Schombert et al. 1992, AJ, 103, 1107) tend to be blue and gas rich. These properties along with their low mean surface luminosity and H i densities imply an inefficient mode of star formation. The Hα images that we presen

  10. STAR-FORMATION THRESHOLDS IN LOW SURFACE BRIGHTNESS GALAXIES

    NARCIS (Netherlands)

    VANDERHULST, JM; SKILLMAN, ED; SMITH, TR; BOTHUN, GD; MCGAUGH, SS; DEBLOK, WJG

    1993-01-01

    Low Surface Brightness (LSB) galaxies appear to have low star formation rates despite their often quite normal H I contents as judged from global H I properties such as M(H I)/L and M(H I)/M(T) ratios. H I imaging with the Very Large Array of the National Radio Astronomy Observatory (the NRAO is ope

  11. Dependence of brightness and darkness assimilation on transparency conditions

    NARCIS (Netherlands)

    Weert, C.M.M. de; Koning, A.R.; Lier, R.J. van

    2004-01-01

    We investigated the dependence of assimilation effects that underlie differences in perceived brightness of two equiluminant shapes. The stimulus consisted of two juxtaposed shapes: an oblong shape and a rectangle, both of which had their elongated axis oriented vertically. In addition, the oblong s

  12. Variations in the Fe mineralogy of bright Martian soil

    Science.gov (United States)

    Murchie, Scott; Mustard, John; Erard, Stephane; Geissler, Paul; Singer, Robert

    1993-01-01

    Bright regions on Mars are interpreted as 'soil' derived by chemical alteration of crustal rocks, whose main pigmentary component is ferric oxide or oxyhydroxide. The mineralogy and mineralogic variability of ferric iron are important evidence for the evolution of Martian soil: mineralogy of ferric phases is sensitive to chemical conditions in their genetic environments, and the spatial distributions of different ferric phases would record a history of both chemical environments and physical mixing. Reflectance spectroscopic studies provide several types of evidence that discriminate possible pigmentary phases, including the position of a crystal field absorption near 0.9 microns and position and strengths of absorptions in the UV-visible wavelength region. Recent telescopic spectra and laboratory measurements of Mars soil analogs suggest that spectral features of bright soil can be explained based on a single pigmentary phase, hematite (alpha-Fe2O3), occurring in both 'nanophase' and more crystalline forms. Here we report on a systematic investigation of Martian bright regions using ISM imaging spectrometer data, in which we examined spatial variations in the position and shape of the approximately 0.9 microns absorption. We found both local and regional heterogeneities that indicate differences in Fe mineralogy. These results demonstrate that bright soils do not represent a single lithology that has been homogenized by eolian mixing, and suggest that weathering of soils in different geologic settings has followed different physical and chemical pathways.

  13. 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

  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. The Circum-Galactic Environment of Bright IRAS Galaxies

    CERN Document Server

    Krongold, Y

    2002-01-01

    This paper studies systematically, for the first time, the circumgalactic environment of bright IRAS galaxies as defined by Soifer et al. (1989). While the role of gravitational interaction for luminous and ultraluminous IRAS galaxies has been well established by various studies, the situation is by far more obscure in the IR luminosity range of the bright IRAS sample, 10^{10}Lsol 30^{o}. A control sample, selected from the Center for Astrophysics redshift survey catalogue, includes 90 objects matching the Bright IRAS sample for distribution of isophotal diameter, redshift, and morphological type. From a search of nearby companion galaxies within 250 Kpc on the second-generation Digitized Sky Survey (DSS-II), we found that the circumgalactic environment of the Bright IRAS galaxies contains more large companions than the galaxies in the optically selected control sample, and is similar to that of Seyfert 2 galaxies. We found a weak correlation over a wide range of far IR luminosity (10^9 Lsol < Lfir < 1...

  16. Bright-dark incoherently coupled photovoltaic soliton pair

    Institute of Scientific and Technical Information of China (English)

    Hou Chun-Feng; Pei Yan-Bo; Zhou Zhong-Xiang; Sun Xiu-Dong

    2005-01-01

    The coupling between two mutually incoherent optical beams that propagate collinearly in open-circuit photovoltaic photorefractive media is investigated. It is shown that an incoherently coupled bright-dark spatial soliton pair can be formed due to photovoltaic effect. The physical properties of such a soliton pair are also discussed.

  17. Highly thermostable fluorescent proteins

    Science.gov (United States)

    Bradbury, Andrew M.; Waldo, Geoffrey S.; Kiss, Csaba

    2011-03-22

    Thermostable fluorescent proteins (TSFPs), methods for generating these and other stability-enhanced proteins, polynucleotides encoding such proteins, and assays and method for using the TSFPs and TSFP-encoding nucleic acid molecules are provided. The TSFPs of the invention show extremely enhanced levels of stability and thermotolerance. In one case, for example, a TSFP of the invention is so stable it can be heated to 99.degree. C. for short periods of time without denaturing, and retains 85% of its fluorescence when heated to 80.degree. C. for several minutes. The invention also provides a method for generating stability-enhanced variants of a protein, including but not limited to fluorescent proteins.

  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. Biomimetic Preparation and Dual-Color Bioimaging of Fluorescent Silicon Nanoparticles.

    Science.gov (United States)

    Wu, Sicong; Zhong, Yiling; Zhou, Yanfeng; Song, Bin; Chu, Binbin; Ji, Xiaoyuan; Wu, Yanyan; Su, Yuanyuan; He, Yao

    2015-11-25

    Fluorescent silicon nanoparticles (SiNPs), as the most important zero-dimensional silicon nanostructures, hold high promise for long-awaited silicon-based optic applications. There currently remain major challenges for the green, inexpensive, and mass production of fluorescent SiNPs, resulting in difficulties in sufficiently exploiting the properties of these remarkable materials. Here, we show that fluorescent small-sized (∼3.8 nm) SiNPs can be produced through biomimetic synthesis in rapid (10 min), low-cost, and environmentally benign manners. The as-prepared SiNPs simultaneously feature bright fluorescence (quantum yield (QY), ∼15-20%), narrow emission spectral width (full width at half-maximum (fwhm), ∼30 nm), and nontoxicity, making them as high-quality fluorescent probes for biological imaging in vitro and in vivo.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua [Physics and Astronomy Department, Vanderbilt University, 1807 Station B, Nashville, TN 37235 (United States)

    2014-06-10

    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 ({sup f}licker{sup )} 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 {sub 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.

  1. Fluorescence and cofluorescence enhancement of Tb(Ⅲ) complexes with pyromellitic acid by M (M =Gd,La,Ca,and Sr ions)

    Institute of Scientific and Technical Information of China (English)

    WANG Zhengxiang; CHEN Hong; SHU Wangen; ZHAO Dongbai; ZHOU Zhongcheng

    2004-01-01

    Fluorescence and cofluorescence properties of Tb(Ⅲ) solid complexes were studied using pyromellitic acid (PMA) as ligand and fluorescence inert ions as doping elements. The cofluorescence enhancement, a result of ligand sensitized fluorescence, was observed in Tb(Ⅲ) solid complexes doped with fluorescent inert ions La(Ⅲ), Gd(Ⅲ), Ca(Ⅲ), and Sr(Ⅲ). The effect of the type and content of doping elements on fluorescence enhancement was studied, and optimum conditions were determined. The results show that Gd (La, Ca, Sr) has clear cofluorescence effect in solid complex Tb-M-PMA system, and in present work, rare earth complex fluorescent powder that emits bright green fluorescence at ultraviolet excitation was obtained, which had potential application as fluorescent anti-counterfeit ink.

  2. Tumor-stem cells interactions by fluorescence imaging

    Science.gov (United States)

    Meleshina, Aleksandra V.; Cherkasova, Elena I.; Sergeeva, Ekaterina; Turchin, Ilya V.; Kiseleva, Ekaterina V.; Dashinimaev, Erdem B.; Shirmanova, Marina V.; Zagaynova, Elena V.

    2013-02-01

    Recently, great deal of interest is investigation the function of the stem cells (SC) in tumors. In this study, we studied «recipient-tumor- fluorescent stem cells » system using the methods of in vivo imaging and laser scanning microscopy (LSM). We used adipose-derived adult stem (ADAS) cells of human lentiviral transfected with the gene of fluorescent protein Turbo FP635. ADAS cells were administrated into nude mice with transplanted tumor HeLa Kyoto (human cervical carcinoma) at different stages of tumor growth (0-8 days) intravenously or into tumor. In vivo imaging was performed on the experimental setup for epi - luminescence bioimaging (IAP RAS, Nizhny Novgorod). The results of the imaging showed localization of fluorophore tagged stem cells in the spleen on day 5-9 after injection. The sensitivity of the technique may be improved by spectral separation autofluorescence and fluorescence of stem cells. We compared the results of in vivo imaging and confocal laser scanning microscopy (LSM 510 META, Carl Zeiss, Germany). Internal organs of the animals and tumor tissue were investigated. It was shown that with i.v. injection of ADAS, bright fluorescent structures with spectral characteristics corresponding to TurboFP635 protein are locally accumulated in the marrow, lungs and tumors of animals. These findings indicate that ADAS cells integrate in the animal body with transplanted tumor and can be identified by fluorescence bioimaging techniques in vivo and ex vivo.

  3. Synthesis of polymeric fluorescent brightener based on coumarin and its performances on paper as light stabilizer, fluorescent brightener and surface sizing agent

    Science.gov (United States)

    Zhang, Guanghua; Zheng, Hua; Guo, Mingyuan; Du, Lun; Liu, Guojun; Wang, Peng

    2016-03-01

    In this work, a novel polymeric fluorescent brightener based on coumarin (PFBC) was synthesized, using three-step synthetic route, from 7-amino-4-methylcoumarin, coumarin monomer (FBC), Acrylamide (AM) and methacrylatoethyl trimethyl ammonium chloride (DMC). The structure of PFBC was characterized by FT-IR, 1HNMR and GPC. PFBC was applied to paper fiber as light stabilizer, fluorescent brightener and surface sizing agent and its performances were evaluated by measuring the UV-vis, fluorescence, thermal stability, the cationic degree, surface strength and smoothness of paper, the brightness degree of paper and the PC value of paper. Results showed that PFBC had better solubility in water than that of FBC, by measuring the optical properties. Through the surface sizing experiment and UV aging experiment, PFBC not only enhanced the surface strength and smoothness of paper as a surface sizing agent, but also had better effect on anti-UV aging than that of FBC as light stabilizer and fluorescent brightener.

  4. Single fluorescent protein-based Ca2+ sensors with increased dynamic range

    Directory of Open Access Journals (Sweden)

    Labas Yulii A

    2007-06-01

    Full Text Available Abstract Background Genetically encoded sensors developed on the basis of green fluorescent protein (GFP-like proteins are becoming more and more popular instruments for monitoring cellular analytes and enzyme activities in living cells and transgenic organisms. In particular, a number of Ca2+ sensors have been developed, either based on FRET (Fluorescence Resonance Energy Transfer changes between two GFP-mutants or on the change in fluorescence intensity of a single circularly permuted fluorescent protein (cpFP. Results Here we report significant progress on the development of the latter type of Ca2+ sensors. Derived from the knowledge of previously reported cpFP-based sensors, we generated a set of cpFP-based indicators with different spectral properties and fluorescent responses to changes in Ca2+ concentration. Two variants, named Case12 and Case16, were characterized by particular high brightness and superior dynamic range, up to 12-fold and 16.5-fold increase in green fluorescence between Ca2+-free and Ca2+-saturated forms. We demonstrated the high potential of these sensors on various examples, including monitoring of Ca2+ response to a prolonged glutamate treatment in cortical neurons. Conclusion We believe that expanded dynamic range, high brightness and relatively high pH-stability should make Case12 and Case16 popular research tools both in scientific studies and high throughput screening assays.

  5. Wide-field multispectral super-resolution imaging using spin-dependent fluorescence in nanodiamonds.

    Science.gov (United States)

    Chen, Edward H; Gaathon, Ophir; Trusheim, Matthew E; Englund, Dirk

    2013-05-08

    Recent advances in fluorescence microscopy have enabled spatial resolution below the diffraction limit by localizing multiple temporally or spectrally distinguishable fluorophores. Here, we introduce a super-resolution technique that deterministically controls the brightness of uniquely addressable, photostable emitters. We modulate the fluorescence brightness of negatively charged nitrogen-vacancy (NV(-)) centers in nanodiamonds through magnetic resonance techniques. Using a CCD camera, this "deterministic emitter switch microscopy" (DESM) technique enables super-resolution imaging with localization down to 12 nm across a 35 × 35 μm(2) area. DESM is particularly well suited for biological applications such as multispectral particle tracking since fluorescent nanodiamonds are not only cytocompatible but also nonbleaching and bright. We observe fluorescence count rates exceeding 1.5 × 10(6) photons per second from single NV(-) centers at saturation. When combined with emerging NV(-)-based techniques for sensing magnetic and electric fields, DESM opens the door to rapid, super-resolution imaging for tracking and sensing applications in the life and physical sciences.

  6. Laser fluorescence bronchoscope for localization of occult lung tumors

    Energy Technology Data Exchange (ETDEWEB)

    Profio, A.E.; Doiron, D.R.; King, E.G.

    1979-11-01

    A system for imaging occult bronchogenic carcinoma by the fluorescence of previously-injected, tumor-specific compound hematoporphyrin-derivative has been assembled and successfully used to locate a tumor l mm thick. The violet excitation source is a krypton ion laser coupled to fused quartz fiber light conductor. An electrostatic image intensifier attached to a standard flexible fiberoptic bronchoscope provides a bright image even at relatively low irradiance. A red secondary filter rejects most reflected background and autofluorescence. Sensitivity and contrast capability of the system should permit detection of a tumor less than 0.1 mm thick.

  7. A ROSAT Bright Source Catalog Survey with the Swift Satellite

    CERN Document Server

    Fox, D B

    2004-01-01

    We consider the prospects for a complete survey of the 18,811 sources of the ROSAT All-Sky Survey Bright Source Catalog (BSC) with NASA's Swift gamma-ray burst (GRB) mission. By observing each BSC source for 500 s with the satellite's imaging X-ray and UV/optical telescopes, this "Swift Bright (Source) Catalog Survey" (Swift-BCS) would derive ~20 mCrab, 10-100 keV) with the wide-field Burst Alert Telescope (BAT); and a two-year all-sky BAT survey down to >~1 mCrab. The resulting expansion of the catalog of identified X-ray sources from 2000 to 18,000 will provide a greatly-enriched set of targets for observation by XMM-Newton, Chandra, and future high-energy observatories.

  8. Contrast Enhancement Using Brightness Preserving Histogram Plateau Limit Technique

    Directory of Open Access Journals (Sweden)

    K. Santhi

    2014-07-01

    Full Text Available Contrast enhancement is an important factor in the gray scale images. One of the widely accepted contrast enhancement method is the Histogram equalization (HE. HE achieves comparatively better performance on almost all types of image but sometimes produces excessive visual deterioration. The proposed Contrast Enhancement using Brightness Preserving Histogram Plateau Limit (CEBPHPL method provides better brightness preservation without allowing in excess of contrast improvement measure. This method decomposes the input image by computing the local maxima of the smoothed image using Gaussian filter which reduces the noise. Then the clipping process has been implemented which provides the good enhancement rate than the conventional methods. The experimental result of the proposed CEBPHPL is better than the existing methods.

  9. Cometary activity in 2060 Chiron at minimum brightness

    CERN Document Server

    Silva, A M; Silva, Adrian M.; Cellone, Sergio A.

    2001-01-01

    We present two-colour CCD imaging of 2060 Chiron obtained between 1996 and 1998 with the 2.15 m telescope at CASLEO (San Juan, Argentina). These post-perihelion observations show that Chiron was then near its historical brightness minima, however a coma was clearly detected. The dynamical state of the coma is studied by means of azimuthally averaged surface brightness profiles, which show the signatures of radiation pressure on the dust grain distribution. Aperture photometry shows an achromatic dimming with an amplitude \\~ 0.09 mag in approximately one hour. If due to rotation of the nucleus, this rather high amplitude is used to derive a new value for the nuclear magnitude, m_0 ~ 6.80 mag.

  10. Optical interferometry and adaptive optics of bright transients

    CERN Document Server

    Millour, Florentin; Meilland, Anthony; Nardetto, Nicolas

    2014-01-01

    Bright optical transients (i.e. transients typically visible with the naked eye) are populated mainly by novae eruptions plus a few supernovae (among which the SN1987a event). One bright nova happen every two years, either in the North ot in the South hemisphere. It occurs that current interferometers have matching sensitivities, with typically visible or infrared limiting magnitude in the range 5--7. The temporal development of the fireball, followed by a dust formation phase or the appearance of many coronal lines can be sudied with the Very Large Telescope Interferometer. The detailed geometry of the first phases of novae in outburst remains virtually unexplored. This paper summarizes the work which has been done to date using the VLTI.

  11. Microwave Brightness Temperature and Lunar Son Dielectric Property Retrieve

    Institute of Scientific and Technical Information of China (English)

    J. Wu; D.H. Li; A.T. Altyntsev; B.I. Lubyshev

    2005-01-01

    Among many scientific objectives of lunar exploration, investigations on lunar soil become more and more attractive to the scientists duo to the existence of abundant 3He and ilmenite in the lunar soil and their possible utilization. Although the soil composition determination on the lunar surface is available by visible light spectrometer, γ/X-ray spectrometer etc, the evaluations on the total reserves of 3He and ilmenite in the lunar deep and on the thickness of the lunar soil are still impossible so far. In this paper, the authors first give a rough analysis of the microwave brightness temperature images of the lunar disc observed using the NRAO 12 Meter Telescope and Siberian Solar Radio Telescope; then introduce our researches on the microwave dielectric properties of lunar soil simulators; finally, discuss some basic relations between the microwave brightness temperature and lunar soil properties.

  12. Bright solitons in a PT-symmetric chain of dimers

    CERN Document Server

    Kirikchi, Omar B; Susanto, Hadi

    2016-01-01

    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 Schrodinger 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 anti-continuum 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, on the contrary of 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 quart...

  13. BRITE-Constellation: Nanosatellites for Precision Photometry of Bright Stars

    CERN Document Server

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

    2013-01-01

    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. The current mission design consists of three pairs of 7 kg nanosats from Austria, Canada and Poland carrying optical telescopes and CCDs. One instrument in each pair is equipped with a blue filter; the other, a red filter. The first two nanosats are UNIBRITE, designed and built by University of Toronto Institute for Aerospace Studies - Space Flight Laboratory and its twin, BRITE-Austria, built by the Technical University Graz with support of UTIAS-SFL. They were launched on 25 February 2013 by the Indian Space Agency under contract to the Canadian Space Agency into a low-Earth dusk-dawn polar orbit.

  14. Histogram Equalization with Range Offset for Brightness Preserved Image Enhancement

    Directory of Open Access Journals (Sweden)

    Haidi Ibrahim

    2011-12-01

    Full Text Available In this paper, a simple modification to Global Histogram Equalization (GHE, a well known digital image enhancement method, has been proposed. This proposed method known as Histogram Equalization with Range Offset (HERO is divided into two stages. In its first stage, an intensity mapping function is constructed by using the cumulative density function of the input image, similar to GHE. Then, during the second stage, an offset for the intensity mapping function will be determined to maintain the mean brightness of the image, which is a crucial criterion for digital image enhancement in consumer electronic products. Comparison with some of the current histogram equalization based enhancement methods shows that HERO successfully preserves the mean brightness and give good enhancement to the image.

  15. The brightness and spatial distributions of terrestrial radio sources

    CERN Document Server

    Offringa, A R; Zaroubi, S; Koopmans, L V E; Wijnholds, S J; Abdalla, F B; Brouw, W N; Ciardi, B; Iliev, I T; Harker, G J A; Mellema, G; Bernardi, G; Zarka, P; Ghosh, A; Alexov, A; Anderson, J; Asgekar, A; Avruch, I M; Beck, R; Bell, M E; Bell, M R; Bentum, M J; Best, P; Bîrzan, L; Breitling, F; Broderick, J; Brüggen, M; Butcher, H R; de Gasperin, F; de Geus, E; de Vos, M; Duscha, S; Eislöffel, J; Fallows, R A; Ferrari, C; Frieswijk, W; Garrett, M A; Grießmeier, J; Hassall, T E; Horneffer, A; Iacobelli, M; Juette, E; Karastergiou, A; Klijn, W; Kondratiev, V I; Kuniyoshi, M; Kuper, G; van Leeuwen, J; Loose, M; Maat, P; Macario, G; Mann, G; McKean, J P; Meulman, H; Norden, M J; Orru, E; Paas, H; Pandey-Pommier, M; Pizzo, R; Polatidis, A G; Rafferty, D; Reich, W; van Nieuwpoort, R; Röttgering, H; Scaife, A M M; Sluman, J; Smirnov, O; Sobey, C; Tagger, M; Tang, Y; Tasse, C; ter Veen, S; Toribio, C; Vermeulen, R; Vocks, C; van Weeren, R J; Wise, M W; Wucknitz, O

    2013-01-01

    Faint undetected sources of radio-frequency interference (RFI) might become visible in long radio observations when they are consistently present over time. Thereby, they might obstruct the detection of the weak astronomical signals of interest. This issue is especially important for Epoch of Reionisation (EoR) projects that try to detect the faint redshifted HI signals from the time of the earliest structures in the Universe. We explore the RFI situation at 30-163 MHz by studying brightness histograms of visibility data observed with LOFAR, similar to radio-source-count analyses that are used in cosmology. An empirical RFI distribution model is derived that allows the simulation of RFI in radio observations. The brightness histograms show an RFI distribution that follows a power-law distribution with an estimated exponent around -1.5. With several assumptions, this can be explained with a uniform distribution of terrestrial radio sources whose radiation follows existing propagation models. Extrapolation of t...

  16. Extremely High Current, High-Brightness Energy Recovery Linac

    CERN Document Server

    Ben-Zvi, Ilan; Beavis, Dana; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Burger, Al; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Favale, Anthony; Gassner, David M; Grimes, Jacob T; Hahn, Harald; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Kneisel, Peter; Lambiase, Robert; Litvinenko, Vladimir N; McIntyre, Gary; Meng, Wuzheng; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Segalov, Zvi; Smith, Kevin T; Todd, Alan M M; Warren-Funk, L; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Yip, Kin; Zaltsman, Alex; Zhao, Yongxiang

    2005-01-01

    Next generation ERL light-sources, high-energy electron coolers, high-power Free-Electron Lasers, powerful Compton X-ray sources and many other accelerators were made possible by the emerging technology of high-power, high-brightness electron beams. In order to get the anticipated performance level of ampere-class currents, many technological barriers are yet to be broken. BNL's Collider-Accelerator Department is pursuing some of these technologies for its electron cooling of RHIC application, as well as a possible future electron-hadron collider. We will describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun and an accelerator cavity capable of producing low emittance (about 1 micron rms normalized) one nano-Coulomb bunches at currents of the order of one ampere average.

  17. 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.

  18. Microwave brightness temperature imaging and dielectric properties of lunar soil

    Indian Academy of Sciences (India)

    Wu Ji; Li Dihui; Zhang Xiaohui; Jiang Jingshan; A T Altyntsev; B I Lubyshev

    2005-12-01

    Among many scientific objectives of lunar exploration, investigations on lunar soil become attractive due to the existence of He3 and ilmenite in the lunar soil and their possible utilization as nuclear fuel for power generation.Although the composition of the lunar surface soil can be determined by optical and /X-ray spectrometers, etc., the evaluation of the total reserves of He3 and ilmenite within the regolith and in the lunar interior are still not available.In this paper,we give a rough analysis of the microwave brightness temperature images of the lunar disc observed using the NRAO 12 meter Telescope and Siberian Solar Radio Telescope.We also present the results of the microwave dielectric properties of terrestrial analogues of lunar soil and,discuss some basic relations between the microwave brightness temperature and lunar soil properties.

  19. Operational Performance Improvements to BRIght Target Explorer Constellation

    Science.gov (United States)

    Choi, Seung Yun

    The BRIght Target Explorer (BRITE)-Constellation is composed of six nano-satellites funded by Austria, Canada, and Poland, and each of them is equipped with an optical telescope that observes stars with visual magnitude +3.5 or brighter. BRITE-Constellation has provided numerous images of bright stars from Low Earth Orbit, which will eventually lead to investigation of origin of the Universe. This thesis presents the contribution of the author to BRITE mission, especially in BRITE Operations. The author performed antenna steering experiments on UniBRITE and BRITE-Toronto, to improve data downlink. To improve scientific data collection from BRITE satellites, the author computed available observation time for multiple targets every orbit, which resulted in collection of twice the amount of scientific data. Also, the author increased the available observation time for each target from 32 minutes to 48 minutes by improving the performance of the star tracker on-board BRITE-Toronto.

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

    Science.gov (United States)

    Roncato, Sergio

    2014-01-01

    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 gray 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 is 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.

  1. 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

  2. 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

  3. Hybrid bright-field and hologram imaging of cell dynamics

    Science.gov (United States)

    Byeon, Hyeokjun; Lee, Jaehyun; Doh, Junsang; Lee, Sang Joon

    2016-09-01

    Volumetric observation is essential for understanding the details of complex biological phenomena. In this study, a bright-field microscope, which provides information on a specific 2D plane, and a holographic microscope, which provides information spread over 3D volumes, are integrated to acquire two complementary images simultaneously. The developed system was successfully applied to capture distinct T-cell adhesion dynamics on inflamed endothelial layers, including capture, rolling, crawling, transendothelial migration, and subendothelial migration.

  4. Production of strongly bound 39K bright solitons

    CERN Document Server

    Lepoutre, S; Boissé, A; Berthet, G; Salomon, G; Aspect, A; Bourdel, T

    2016-01-01

    We report on the production of 39 K matter-wave bright solitons, i.e., 1D matter-waves that propagate without dispersion thanks to attractive interactions. The volume of the soliton is studied as a function of the scattering length through three-body losses, revealing peak densities as high as $\\sim 5 \\times 10^{20} m^{-3}$. Our solitons, close to the collapse threshold, are strongly bound and will find applications in fundamental physics and atom interferometry.

  5. The Morphology of Low Surface Brightness Disk Galaxies

    Science.gov (United States)

    McGaugh, S.; Schombert, J.; Bothun, G.

    1994-01-01

    Images of a sample of low surface brightness (LSB) disk galaxies are presented. These galaxies are generally late types; however, they are not dwarfs, being intrinsically large and luminous. The morphology of LSB galaxies is discussed in terms of the physical interpretation of the Hubble sequence, the stages of which are found to be nonlinear in the sense that smaller physical differences separate mid to early type spirals than late types.

  6. Highly indistinguishable on-demand resonance fluorescence photons from a deterministic quantum dot micropillar device with 74% extraction efficiency

    DEFF Research Database (Denmark)

    Gregersen, Niels

    2016-01-01

    The implementation and engineering of bright and coherent solid state quantum light sources is key for the realization of both on chip and remote quantum networks. Despite tremendous efforts for more than 15 years, the combination of these two key prerequisites in a single, potentially scalable...... device is a major challenge. Here, we report on the observation of bright single photon emission generated via pulsed, resonance fluorescence conditions from a single quantum dot (QD) deterministically centered in a micropillar cavity device via cryogenic optical lithography. The brightness of the QD...... fluorescence is greatly enhanced on resonance with the fundamental mode of the pillar, leading to an overall device efficiency of η = (74 ± 4) % for a single photon emission as pure as g (2) (0) = 0.0092 ± 0.0004. The combination of large Purcell enhancement and resonant pumping conditions allows us to observe...

  7. Red fluorescence increases with depth in reef fishes, supporting a visual function, not UV protection.

    Science.gov (United States)

    Meadows, Melissa G; Anthes, Nils; Dangelmayer, Sandra; Alwany, Magdy A; Gerlach, Tobias; Schulte, Gregor; Sprenger, Dennis; Theobald, Jennifer; Michiels, Nico K

    2014-09-07

    Why do some marine fishes exhibit striking patterns of natural red fluorescence? In this study, we contrast two non-exclusive hypotheses: (i) that UV absorption by fluorescent pigments offers significant photoprotection in shallow water, where UV irradiance is strongest; and (ii) that red fluorescence enhances visual contrast at depths below -10 m, where most light in the 'red' 600-700 nm range has been absorbed. Whereas the photoprotection hypothesis predicts fluorescence to be stronger near the surface and weaker in deeper water, the visual contrast hypothesis predicts the opposite. We used fluorometry to measure red fluorescence brightness in vivo in individuals belonging to eight common small reef fish species with conspicuously red fluorescent eyes. Fluorescence was significantly brighter in specimens from the -20 m sites than in those from -5 m sites in six out of eight species. No difference was found in the remaining two. Our results support the visual contrast hypothesis. We discuss the possible roles fluorescence may play in fish visual ecology and highlight the possibility that fluorescent light emission from the eyes in particular may be used to detect cryptic prey.

  8. 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.

  9. BRITE-Constellation: nanosatellites for precision photometry of bright stars

    CERN Document Server

    Weiss, W W; Moffat, A F J; Schwarzenberg-Czerny, A; Koudelka, O F; Grant, C C; Zee, R E; Kuschnig, R; Mochnacki, St; Matthews, J M; Orleanski, P; Pamyatnykh, A; Pigulski, A; Alves, J; Guedel, M; Handler, G; Wade, G A; Zwintz, K; CCD,

    2014-01-01

    BRITE-Constellation (where BRITE stands for BRIght Target Explorer) is an international nanosatellite mission to monitor photometrically, in two colours, the brightness and temperature variations of stars generally brighter than mag(V) ~ 4, with precision and time coverage not possible from the ground. The current mission design consists of six nanosats (hence Constellation): two from Austria, two from Canada, and two from Poland. Each 7 kg nanosat carries an optical telescope of aperture 3 cm feeding an uncooled CCD. One instrument in each pair is equipped with a blue filter, the other with a red filter. Each BRITE instrument has a wide field of view (~24 degrees), so up to about 15 bright stars can be observed simultaneously, sampled in 32 pixel x 32 pixel sub-rasters. Photometry of additional fainter targets, with reduced precision but thorough time sampling, will be possible through onboard data processing. The BRITE sample is dominated by the most intrinsically luminous stars: massive stars seen at all e...

  10. Night-sky brightness and extinction at Mt. Shatdzhatmaz

    CERN Document Server

    Kornilov, V; Voziakova, O; Shatsky, N; Safonov, B; Gorbunov, I; Potanin, S; Cheryasov, D; Senik, V

    2016-01-01

    The photometric sky quality of Mt. Shatdzhatmaz, the site of Sternberg Astronomical Institute Caucasian Observatory 2.5 m telescope, is characterized here by the statistics of the night-time sky brightness and extinction. The data were obtained as a by-product of atmospheric optical turbulence measurements with the MASS (Multi-Aperture Scintillation Sensor) device conducted in 2007--2013. The factors biasing night-sky brightness measurements are considered and a technique to reduce their impact on the statistics is proposed. The single-band photometric estimations provided by MASS are easy to transform to the standard photometric bands. The median moonless night-sky brightness is 22.1, 21.1, 20.3, and 19.0 mag per square arcsec for the $B$, $V$, $R$, and $I$ spectral bands, respectively. The median extinction coefficients for the same photometric bands are 0.28, 0.17, 0.13, and 0.09 mag. The best atmospheric transparency is observed in winter.

  11. Giant Low Surface Brightness Galaxies: Evolution in Isolation

    Indian Academy of Sciences (India)

    M. Das

    2013-03-01

    Giant Low Surface Brightness (GLSB) galaxies are amongst the most massive spiral galaxies that we know of in our Universe. Although they fall in the class of late type spiral galaxies, their properties are far more extreme. They have very faint stellar disks that are extremely rich in neutral hydrogen gas but low in star formation and hence low in surface brightness. They often have bright bulges that are similar to those found in early type galaxies. The bulges can host low luminosity Active Galactic Nuclei (AGN) that have relatively low mass black holes. GLSB galaxies are usually isolated systems and are rarely found to be interacting with other galaxies. In fact many GLSB galaxies are found under dense regions close to the edges of voids. These galaxies have very massive dark matter halos that also contribute to their stability and lack of evolution. In this paper we briefly review the properties of this unique class of galaxies and conclude that both their isolation and their massive dark matter halos have led to the low star formation rates and the slower rate of evolution in these galaxies.

  12. Normal Globular Cluster Systems in Massive Low Surface Brightness Galaxies

    CERN Document Server

    Villegas, Daniela; Jordán, Andrés; Goudfrooij, Paul; Zwaan, Martin

    2007-01-01

    We present the results of a study of the globular cluster systems of 6 massive spiral galaxies, originally cataloged as low surface brightness galaxies but here shown to span a wide range of central surface brightness values, including two intermediate to low surface brightness galaxies. We used the Advanced Camera for Surveys on board HST to obtain photometry in the F475W and F775W bands and select sources with photometric and morphological properties consistent with those of globular clusters. A total of 206 candidates were identified in our target galaxies. From a direct comparison with the Galactic globular cluster system we derive specific frequency values for each galaxy that are in the expected range for late-type galaxies. We show that the globular cluster candidates in all galaxies have properties consistent with globular cluster systems of previously studied galaxies in terms of luminosity, sizes and color. We establish the presence of globular clusters in the two intermediate to low surface brightn...

  13. An All-Sky Catalog of Bright M Dwarfs

    CERN Document Server

    Lépine, Sébastien

    2011-01-01

    We present an all-sky catalog of M dwarf stars with apparent infrared magnitude J40 mas/yr, supplemented on the bright end with the TYCHO-2 catalog. Completeness tests which account for kinematic (proper motion) bias suggest that our catalog represents ~75% of the estimated ~11,900 M dwarfs with J<10 expected to populate the entire sky. Our catalog is, however, significantly more complete for the Northern sky (~90%) than it is for the South (~60%). Stars are identified as cool, red M dwarfs from a combination of optical and infrared color cuts, and are distinguished from background M giants and highly-reddened stars using either existing parallax measurements or, if such measurements are lacking, on their location in an optical-to-infrared reduced proper motion diagram. These bright M dwarfs are all prime targets for exoplanet surveys using the Doppler radial velocity or transit methods; the combination of low-mass and bright apparent magnitude should make possible the detection of Earth-size planets on sh...

  14. South African night sky brightness during high aerosol epochs

    CERN Document Server

    Winkler, Hartmut; Marang, Fred

    2014-01-01

    Sky conditions in the remote, dry north-western interior of South Africa are now the subject of considerable interest in view of the imminent construction of numerous solar power plants in this area. Furthermore, the part of this region in which the core of the SKA is to be located (which includes SALT) has been declared an Astronomical Advantage Zone, for which sky brightness monitoring will now be mandatory. In this project we seek to characterise the sky brightness profile under a variety of atmospheric conditions. Key factors are of course the lunar phase and altitude, but in addition the sky brightness is also significantly affected by the atmospheric aerosol loading, as that influences light beam scattering. In this paper we chose to investigate the sky characteristics soon after the Mount Pinatubo volcanic eruption in 1991, which resulted in huge ash masses reaching the stratosphere (where they affected solar irradiance for several years). We re-reduced photometric sky measurements from the South Afric...

  15. Nine New Fluorescent Probes

    Science.gov (United States)

    Lin, Tsung-I.; Jovanovic, Misa V.; Dowben, Robert M.

    1989-06-01

    Absorption and fluorescence spectroscopic studies are reported here for nine new fluorescent probes recently synthesized in our laboratories: four pyrene derivatives with substituents of (i) 1,3-diacetoxy-6,8-dichlorosulfonyl, (ii) 1,3-dihydroxy-6,8-disodiumsulfonate, (iii) 1,3-disodiumsulfonate, and (iv) l-ethoxy-3,6,8-trisodiumsulfonate groups, and five [7-julolidino] coumarin derivatives with substituents of (v) 3-carboxylate-4-methyl, (vi) 3- methylcarboxylate, (vii) 3-acetate-4-methyl, (viii) 3-propionate-4-methyl, and (ix) 3-sulfonate-4-methyl groups. Pyrene compounds i and ii and coumarin compounds v and vi exhibit interesting absorbance and fluorescence properties: their absorption maxima are red shifted compared to the parent compound to the blue-green region, and the band width broadens considerably. All four blue-absorbing dyes fluoresce intensely in the green region, and the two pyrene compounds emit at such long wavelengths without formation of excimers. The fluorescence properties of these compounds are quite environment-sensitive: considerable spectral shifts and fluorescence intensity changes have been observed in the pH range from 3 to 10 and in a wide variety of polar and hydrophobic solvents with vastly different dielectric constants. The high extinction and fluorescence quantum yield of these probes make them ideal fluorescent labeling reagents for proteins, antibodies, nucleic acids, and cellular organelles. The pH and hydrophobicity-dependent fluorescence changes can be utilized as optical pH and/or hydrophobicity indicators for mapping environmental difference in various cellular components in a single cell. Since all nine probes absorb in the UV, but emit at different wavelengths in the visible, these two groups of compounds offer an advantage of utilizing a single monochromatic light source (e.g., a nitrogen laser) to achieve multi-wavelength detection for flow cytometry application. As a first step to explore potential application in

  16. Bright and photostable push-pull pyrene dye visualizes lipid order variation between plasma and intracellular membranes

    Science.gov (United States)

    Niko, Yosuke; Didier, Pascal; Mely, Yves; Konishi, Gen-Ichi; Klymchenko, Andrey S.

    2016-01-01

    Imaging lipid organization in cell membranes requires advanced fluorescent probes. Here, we show that a recently synthesized push-pull pyrene (PA), similarly to popular probe Laurdan, changes the emission maximum as a function of lipid order, but outperforms it by spectroscopic properties. In addition to red-shifted absorption compatible with common 405 nm diode laser, PA shows higher brightness and much higher photostability than Laurdan in apolar membrane environments. Moreover, PA is compatible with two-photon excitation at wavelengths >800 nm, which was successfully used for ratiometric imaging of coexisting liquid ordered and disordered phases in giant unilamellar vesicles. Fluorescence confocal microscopy in Hela cells revealed that PA efficiently stains the plasma membrane and the intracellular membranes at >20-fold lower concentrations, as compared to Laurdan. Finally, ratiometric imaging using PA reveals variation of lipid order within different cellular compartments: plasma membranes are close to liquid ordered phase of model membranes composed of sphingomyelin and cholesterol, while intracellular membranes are much less ordered, matching well membranes composed of unsaturated phospholipids without cholesterol. These differences in the lipid order were confirmed by fluorescence lifetime imaging (FLIM) at the blue edge of PA emission band. PA probe constitutes thus a new powerful tool for biomembrane research.

  17. Wave and Wind Direction Effects on SFMR Brightness Temperatures

    Science.gov (United States)

    Holbach, Heather; Uhlhorn, Eric; Bourassa, Mark

    2015-04-01

    Surface winds in a tropical cyclone are essential for determining its strength. Currently the Stepped-Frequency Microwave Radiometer (SFMR) and Global Positioning System (GPS) dropwindsondes are the main instruments used for obtaining in situ surface wind measurements. The platforms for these instruments are the National Oceanographic and Atmospheric Administration (NOAA) P-3 and Air Force C-130J hurricane hunter aircraft. The SFMR measures sea surface microwave brightness temperatures at six frequencies ranging from 4.7 to 7.2 GHz. Surface wind speed estimates are obtained from these brightness temperatures by using a retrieval algorithm that employs a geophysical model function relating surface emissivity and wind speed. The SFMR is designed to obtain a single nadir track of surface wind speeds directly beneath the aircraft during level flight and not when turning because of the complexity of the wave field and foam distribution when the SFMR views the surface off-nadir or during aircraft rolls. However, the effects of the wave field on the measurements can be investigated using measurements obtained during the 2008 and 2014 Atlantic hurricane seasons. An SFMR module was flown in precipitation-free regions of the tropical cyclones to collect data at specified roll angles of 15°, 30°, 45°, and 60° in some cases. Excess brightness temperatures are then calculated with respect to zero wind speed values and independent of wind direction. An asymmetry is found in the resulting excess brightness temperatures. It is hypothesized that this asymmetry is caused by the direction of wave propagation and the angle at which the wave field is viewed by the SFMR. Wind direction may also play a role in the asymmetry. To analyze the asymmetry further measurement from WindSat will be used. Once the relationship is determined between surface wind speed, brightness temperature, and incidence angle a technique will be developed to obtain a surface wind speed when the aircraft is

  18. Stroboscopic fluorescence lifetime imaging.

    Science.gov (United States)

    Holton, Mark D; Silvestre, Oscar R; Errington, Rachel J; Smith, Paul J; Matthews, Daniel R; Rees, Paul; Summers, Huw D

    2009-03-30

    We report a fluorescence lifetime imaging technique that uses the time integrated response to a periodic optical excitation, eliminating the need for time resolution in detection. A Dirac pulse train of variable period is used to probe the frequency response of the total fluorescence per pulse leading to a frequency roll-off that is dependent on the relaxation rate of the fluorophores. The technique is validated by demonstrating wide-field, realtime, lifetime imaging of the endocytosis of inorganic quantum dots by a cancer cell line. Surface charging of the dots in the intra-cellular environment produces a switch in the fluorescence lifetime from approximately 40 ns to technique offers lifetime based imaging at video rates with standard CCD cameras and has application in probing millisecond cell dynamics and in high throughput imaging assays.

  19. 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

  20. Gold nanoclusters with enhanced tunable fluorescence as bioimaging probes.

    Science.gov (United States)

    Palmal, Sharbari; Jana, Nikhil R

    2014-01-01

    Development of unique bioimaging probes offering essential information's about bio environments are an important step forward in biomedical science. Nanotechnology offers variety of novel imaging nanoprobes having high-photo stability as compared to conventional molecular probes which often experience rapid photo bleaching problem. Although great advances have been made on the development of semiconductor nanocrystals-based fluorescent imaging probes, potential toxicity issue by heavy metal component limits their in vivo therapeutic and clinical application. Recent works show that fluorescent gold clusters (FGCs) can be a promising nontoxic alternative of semiconductor nanocrystals. FGCs derived imaging nanoprobes offer stable and tunable visible emission, small hydrodynamic size, high biocompatibility and have been exploited in variety in vitro and in vivo imaging applications. In this review, we will focus on the synthetic advances and bioimaging application potentials of FGCs. In particular, we will emphasize on functional FGCs that are bright and stable enough to be useful as bioimaging probes.

  1. Novel fluorescent carbonic nanomaterials for sensing and imaging

    Science.gov (United States)

    Demchenko, Alexander P.; Dekaliuk, Mariia O.

    2013-12-01

    Small brightly fluorescent carbon nanoparticles have emerged as a new class of materials important for sensing and imaging applications. We analyze comparatively the properties of nanodiamonds, graphene and graphene oxide ‘dots’, of modified carbon nanotubes and of diverse carbon nanoparticles known as ‘C-dots’ obtained by different methods. The mechanisms of their light absorption and luminescence emission are still unresolved and the arguments are presented for their common origin. Regarding present and potential applications, we provide critical comparison with the other types of fluorescence reporters, such as organic dyes and semiconductor quantum dots. Their most prospective applications in sensing (based on the changes of intensity, FRET and lifetime) and in imaging technologies on the level of living cells and whole bodies are overviewed. The possibilities for design on their basis of multifunctional nanocomposites on a broader scale of theranostics are outlined.

  2. Lyman-alpha Emission From Cosmic Structure I: Fluorescence

    CERN Document Server

    Kollmeier, Juna A; Davé, Romeel; Gould, Andrew; Katz, Neal; Miralda-Escudé, Jordi; Weinberg, David H

    2009-01-01

    We present predictions for the fluorescent Lyman-alpha emission signature arising from photoionized, optically thick structures in Smoothed Particle Hydrodynamic (SPH) cosmological simulations of a Lambda-CDM universe using a Monte Carlo Lyman-alpha radiative transfer code. We calculate the expected Lyman-alpha image and 2-dimensional spectra for gas exposed to a uniform ultraviolet ionizing background as well as gas exposed additionally to the photoionizing radiation from a local quasar, after correcting for the self-shielding of hydrogen. As a test of our numerical methods and for application to current observations, we examine simplified analytic structures that are uniformly or anisotropically illuminated. We compare these results with recent observations. We discuss future observing campaigns on large telescopes and realistic strategies for detecting fluorescence owing to the ambient metagalactic ionization and in regions close to bright quasars. While it will take hundreds of hours on the current genera...

  3. Efficacy of a single sequence of intermittent bright light pulses for delaying circadian phase in humans. : Phase delaying efficacy of intermittent bright light

    OpenAIRE

    2004-01-01

    International audience; It has been shown in animal studies that exposure to brief pulses of bright light can phase shift the circadian pacemaker and that the resetting action of light is most efficient during the first minutes of light exposure. In humans, multiple consecutive days of exposure to brief bright light pulses have been shown to phase shift the circadian pacemaker. The aim of the present study was to determine whether a single sequence of brief bright light pulses administered du...

  4. Collision induced splitting of bright soliton in Bose-Einstein condensate

    Institute of Scientific and Technical Information of China (English)

    Wang Yue-Yue; Zhang Jie-Fang

    2009-01-01

    This paper studies the collision dynamics of bright soliton in Bose-Einstein condensate with trapezoid potential. It is found that besides the total reflection and total transmission, one bright soliton can be divided into two bright solitons with different amplitudes in a controllable manner.

  5. Synthesis and characterization of a Noble metal Enhanced Optical Nanohybrid (NEON): a high brightness detection platform based on a dye-doped silica nanoparticle.

    Science.gov (United States)

    Roy, Shibsekhar; Dixit, Chandra K; Woolley, Robert; O'Kennedy, Richard; McDonagh, Colette

    2012-05-29

    A highly bright and photostable, fluorescent nanohybrid particle is presented which consists of gold nanoparticles (GNPs) embedded in dye-doped silica in a core-shell configuration. The dye used is the near-infrared emitting 4,5-benzo-5'-(iodoacetaminomethyl)-1',3,3,3',3'-pentamethyl-1-(4-sulfobutyl) indodicarbo cyanine. The nanohybrid architecture comprises a GNP core which is separated from a layer of dye molecules by a 15 nm buffer layer and has an outer protective, undoped silica shell. Using this architecture, a brightness factor of 550 has been achieved compared to the free dye. This hybrid system, referred to as Noble metal Enhanced Optical Nanohybrid (NEON) in this paper, is the first nanohybrid construct to our knowledge which demonstrates such tunable fluorescence property. NEON has enhanced photostability compared to the free dye and compared to a control particle without GNPs. Furthermore, the NEON particle, when used as a fluorescent label in a model bioassay, shows improved performance over assays using a conventional single dye molecule label.

  6. Hydroxy-terminated conjugated polymer nanoparticles have near-unity bright fraction and reveal cholesterol-dependence of IGF1R nanodomains.

    Science.gov (United States)

    Koner, Apurba L; Krndija, Denis; Hou, Qiong; Sherratt, David J; Howarth, Mark

    2013-02-26

    Fluorescent nanoparticles have enabled many discoveries regarding how molecular machines function. Quantum dots have been the dominant class of fluorescent nanoparticles but suffer from blinking and from a substantial dark fraction--particles where the fluorescence is never seen--complicating any analysis of biological function. Nanoparticles composed of conjugated fluorescent polymers (Pdots) have recently been shown to have high brightness and no blinking. Here we develop a robust and efficient means to measure the dark fraction of Pdots, conjugating Atto dyes to the nanoparticles and testing fluorescence colocalization of dye and Pdot puncta. This established that the Pdots we generated had minimal dark fraction: ∼3%. The application of nanoparticles in biological environments is highly sensitive to surface functionalization. For Pdots we found that passivation with uncharged hydroxy-terminated polyethylene glycol caused a dramatic reduction in nonspecific cell binding and aggregation compared to a charged coating. Using carbonyl di-imidazole the hydroxy-Pdots were functionalized efficiently with streptavidin for high stability targeting, allowing specific labeling of mammalian cells. Type I insulin-like growth factor receptor (IGF1R) regulates cell survival and development, with roles in aging, heart disease, and cancer. We used hydroxy-Pdots to track the dynamics of IGF1R on a breast cancer cell-line, determining the diffusion characteristics and showing cholesterol-containing membrane nanodomains were important for receptor mobility at the plasma membrane. The near-unity bright fraction and low nonspecific binding of hydroxy-Pdots, combined with Pdot photostability and lack of blinking, provides many advantages for investigations at the single molecule level.

  7. Active Detection and Imaging of Nuclear Materials with High-Brightness Gamma Rays

    Energy Technology Data Exchange (ETDEWEB)

    Barty, C J; Gibson, D J; Albert, F; Anderson, S G; Anderson, G G; Betts, S M; Berry, R D; Fisher, S E; Hagmann, C A; Johnson, M S; Messerly, M J; Phan, H H; Semenov, V A; Shverdin, M Y; Tremaine, A M; Hartemann, F V; Siders, C W; McNabb, D P

    2009-02-26

    A Compton scattering {gamma}-ray source, capable of producing photons with energies ranging from 0.1 MeV to 0.9 MeV has been commissioned and characterized, and then used to perform nuclear resonance fluorescence (NRF) experiments. The performances of the two laser systems (one for electron production, one for scattering), the electron photoinjector, and the linear accelerator are also detailed, and {gamma}-ray results are presented. The key source parameters are the size (0.01 mm{sup 2}), horizontal and vertical divergence (6 x 10 mrad{sup 2}), duration (10 ps), spectrum and intensity (10{sup 5} photons/shot). These parameters are summarized by the peak brightness, 1.5 x 10{sup 15} photons/mm{sup 2}/mrad{sup 2}/s/0.1% bandwidth, measured at 478 keV. Additional measurements of the flux as a function of the timing difference between the drive laser pulse and the relativistic photo-electron bunch, {gamma}-ray beam profile, and background evaluations are presented. These results are systematically compared to theoretical models and computer simulations. NRF measurements performed on {sup 7}Li in LiH demonstrate the potential of Compton scattering photon sources to accurately detect isotopes in situ.

  8. Investigating the fluid dynamics of rapid processes within microfluidic devices using bright-field microscopy.

    Science.gov (United States)

    Pirbodaghi, Tohid; Vigolo, Daniele; Akbari, Samin; deMello, Andrew

    2015-05-07

    The widespread application of microfluidic devices in the biological and chemical sciences requires the implementation of complex designs and geometries, which in turn leads to atypical fluid dynamic phenomena. Accordingly, a complete understanding of fluid dynamics in such systems is key in the facile engineering of novel and efficient analytical tools. Herein, we present an accurate approach for studying the fluid dynamics of rapid processes within microfluidic devices using bright-field microscopy with white light illumination and a standard high-speed camera. Specifically, we combine Ghost Particle Velocimetry and the detection of moving objects in automated video surveillance to track submicron size tracing particles via cross correlation between the speckle patterns of successive images. The efficacy of the presented technique is demonstrated by measuring the flow field over a square pillar (80 μm × 80 μm) in a 200 μm wide microchannel at high volumetric flow rates. Experimental results are in excellent agreement with those obtained via computational fluid dynamics simulations. The method is subsequently used to study the dynamics of droplet generation at a flow focusing microfluidic geometry. A unique feature of the presented technique is the ability to perform velocimetry analysis of high-speed phenomena, which is not possible using micron-resolution particle image velocimetry (μPIV) approaches based on confocal or fluorescence microscopy.

  9. FLEX: fluorescence explorer

    NARCIS (Netherlands)

    Stoll, M.Ph.; Court, A.J.; Smorenburg, C.; Visser, H.; Crocco, L.; Heilimo, J.; Honig, A.

    1999-01-01

    FLEX is a scientifically driven space mission to provide demonstration/validation of the instrumentation and technique for measuring the natural fluorescence of vegetation in the Fraunhofer lines. The payload consists of high spectral resolution (0.1-0.3 nm) CCD imaging grating spectrometer with two

  10. Fluorescence Experiments with Quinine

    Science.gov (United States)

    O'Reilly, James E.

    1975-01-01

    Describes a series of experiments which illustrate the analytical capabilities of fluorescence, and outlines two straightforward analyses involving real analyses. These experiments are suitable for an undergraduate instrumental analysis course and require approximately six to seven hours of laboratory time. (MLH)

  11. Limitations of the Oriented Difference of Gaussian Filter in Special Cases of Brightness Perception Illusions.

    Science.gov (United States)

    Bakshi, Ashish; Roy, Sourya; Mallick, Arijit; Ghosh, Kuntal

    2016-03-01

    The Oriented Difference of Gaussian (ODOG) filter of Blakeslee and McCourt has been successfully employed to explain several brightness perception illusions which include illusions of both brightness-contrast type, for example, Simultaneous Brightness Contrast and Grating Induction and the brightness-assimilation type, for example, the White effect and the shifted White effect. Here, we demonstrate some limitations of the ODOG filter in predicting perceived brightness by comparing the ODOG responses to various stimuli (generated by varying two parameters, namely, test patch length and spatial frequency) with experimental observations of the same.

  12. The new World Atlas of Artificial Sky Brightness

    Science.gov (United States)

    Falchi, Fabio; Cinzano, Pierantonio; Kyba, Christopher C. M.; Portnov, Boris A.

    2015-08-01

    I present the main steps toward the completion of the new World Atlas of Artificial Sky Brightness (WA II) and some results. The computational technique has been updated, in comparison to the first World Atlas, to take into account both sources and sites elevation. The elevation data are from USGS GTOPO30 global digital elevation model, with the same pixel size as the WA II maps. The upward emission function used to compute the Atlas is a three parameters function. The parameters can be constrained to the database of Earth based night sky brightness measurements. In this way we can use the better fitting upward function for the final map’s calibration. We maintained constant atmosphere parameters over the entire Earth, identical to those used for the first Atlas (Garstang atmospheric clarity coefficient k=1, equivalent to a vertical extinction at sea level of 0.33 magnitude in the V band). This was done in order to avoid introducing a local bias due to different conditions that may confound the light pollution propagation effects. The radiance data used are those from Visible Infrared Imaging Radiometer Suite (VIIRS) Day-Night Band (DNB) on board the Suomi NPP satellite. The use of this newly available radiance data allows for an increased real resolution, even while maintaining the same 30"x30" lat-lon pixel size. Anyway, a higher resolution is really appreciable only in the immediate proximity of sources of light pollution (e.g. inside a big city). The VIIRS DNB data used for the input data were chosen from the months ranging from May to September in order to avoid introducing bias from the variable snow coverage in mid to high northern latitudes. In the southern hemisphere this problem is far less pronounced. The WA II takes advantage of the now enormous database of Earth based sky brightness measurements obtained mainly with Sky Quality Meters, but also with CCD measurements.

  13. Sleep quality during alcohol withdrawal with bright light therapy.

    Science.gov (United States)

    Schmitz, M; Frey, R; Pichler, P; Röpke, H; Anderer, P; Saletu, B; Rudas, S

    1997-08-01

    1. Alcohol withdrawal is a complex syndrome that ranges from anxiety, insomnia to delirium tremens. Common treatment is the application of sedative medication. Exposure to bright light in the daytime should advance the normal sleep/wake cycle and moreover it should improve the availability of man's adaptive behavior during alcohol withdrawal. 2. This pilot study describes bright light therapy (BL) during alcohol withdrawal in ten alcohol dependent patients (DSM-III-R: 291.80) without any sedative medication. BL (3000 Lux) was administered on day 3 of abstinence between 7.00-9.00 a.m. and 5.00-9.00 p.m. Total-sleep-polysomnography (recordings between 10.30 p.m.-6.00 a.m.) and self-rating scale were performed to compare intraindividual changes during three nights. After one adaptation night (immediately after alcohol withdrawal), one baseline night and one "BL-night" and one "post-BL night" were analysed. 3. At baseline, total sleep time and sleep efficiency were severely deteriorated, but tended to improve in the following nights after BL. Sleep onset latency showed a significant decline after BL. Stages 3 and 4 were reduced at baseline. Latencies to slow wave sleep were significantly shortened after BL. REM increased in the nights after BL. Subjective sleep quality improved after BL. Although the present results, bright light having a possible stabilizing effect on sleep maintenance and sleep architecture during acute alcohol withdrawal, the authors could only derive hypotheses for further ongoing controlled investigations using placebo light, to receive final verification.

  14. 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 (bright 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.

  15. Platinum plasmonic nanostructure arrays for massively parallel single-molecule detection based on enhanced fluorescence measurements.

    Science.gov (United States)

    Saito, Toshiro; Takahashi, Satoshi; Obara, Takayuki; Itabashi, Naoshi; Imai, Kazumichi

    2011-11-04

    We fabricated platinum bowtie nanostructure arrays producing fluorescence enhancement and evaluated their performance using two-photon photoluminescence and single-molecule fluorescence measurements. A comprehensive selection of suitable materials was explored by electromagnetic simulation and Pt was chosen as the plasmonic material for visible light excitation near 500 nm, which is preferable for multicolor dye-labeling applications like DNA sequencing. The observation of bright photoluminescence (λ = 500-600 nm) from each Pt nanostructure, induced by irradiation at 800 nm with a femtosecond laser pulse, clearly indicates that a highly enhanced local field is created near the Pt nanostructure. The attachment of a single dye molecule was attempted between the Pt triangles of each nanostructure by using selective immobilization chemistry. The fluorescence intensities of the single dye molecule localized on the nanostructures were measured. A highly enhanced fluorescence, which was increased by a factor of 30, was observed. The two-photon photoluminescence intensity and fluorescence intensity showed qualitatively consistent gap size dependence. However, the average fluorescence enhancement factor was rather repressed even in the nanostructure with the smallest gap size compared to the large growth of photoluminescence. The variation of the position of the dye molecule attached to the nanostructure may influence the wide distribution of the fluorescence enhancement factor and cause the rather small average value of the fluorescence enhancement factor.

  16. Generation of bright soliton through the interaction of black solitons

    CERN Document Server

    Losano, L; Bazeia, D

    2001-01-01

    We report on the possibility of having two black solitons interacting inside a silica fiber that presents normal group-velocity dispersion, to generate a pair of solitons, a vector soliton of the black-bright type. The model obeys a pair of coupled nonlinear Schr\\"odinger equations, that follows in accordance with a Ginzburg-Landau equation describing the anisotropic XY model. We solve the coupled equations using a trial-orbit method, which plays a significant role when the Schr\\"odinger equations are reduced to first order differential equations.

  17. Continuous variable quantum communication with bright entangled optical beams

    Institute of Scientific and Technical Information of China (English)

    XIE Chang-de; ZHANG Jing; PAN Qing; JIA Xiao-jun; PENG Kun-chi

    2006-01-01

    In this paper,we briefly introduce the basic concepts and protocols of continuous variable quantum communication,and then summarize the experimental researches accomplished by our group in this field.The main features of quantum communication systems used in our experiments are:(1) The bright entangled optical beams with the anticorrelated amplitude quadratures and the correlated phase quadratures that serve as the entanglement resources and (2) The Bell-state direct detection systems are utilized in the measurements of quantum entanglement and transmitted signals instead of the usually balanced homodyne detectors.

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

    Indian Academy of Sciences (India)

    Golam Ali Sekh

    2013-08-01

    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 bichromatic lattices and a comparative study is done on the dynamics of solitons with respect to the effective potentials. The effects of dispersion on solitons in bichromatic lattices are studied and it is found that the dispersive spreading can be minimized by appropriate combinations of lattice and interaction parameters. Stability of nondispersive matter-wave solitons is checked from phase portrait analysis.

  19. Spectral Index Changes with Brightness for -Ray Loud Blazars

    Indian Academy of Sciences (India)

    J. H. Yang; R. S. Yang; J. J. Nie; J. H. Fan

    2014-09-01

    Based on Fermi 1FGL and 2FGL data, a sample of 572 -ray loud blazars are selected, in which each source has both -ray flux and spectral index in 1FGL and 2FGL, respectively. Theoretic relation of spectral index changes depending on -ray brightness is obtained. The correlations between the ratio of -ray flux densities and the differences of the -ray spectral indices are discussed for the three subclasses of HBL, LBL and FSRQs. Results show that the ratio is related with the differences for the three subclasses. It is consistent with the theoretical result and it indicates that the spectrum becomes flat as the source brightens in the -ray band.

  20. The Spectral Energy Distribution of Fermi bright blazars

    CERN Document Server

    Abdo, A A; Ajello, M; Axelsson, M; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cavazzuti, E; Cecchi, C; Celik, O; Charles, E; Chaty, S; Chekhtman, A; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Colafrancesco, S; Cominsky, L R; Conrad, J; Costamante, L; Cutini, S; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; Silva, E do Couto e; Drell, P S; Dubois, R; Dumora, D; Farnier, C; Favuzzi, C; Fegan, S J; Focke, W B; Fortin, P; Frailis, M; Fuhrmann, L; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giebels, B; Giglietto, N; Giommi, P; Giordano, F; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guillemot, L; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Healey, S E; Horan, D; Hughes, R E; Itoh, R; Jackson, M S; Johannesson, G; Johnson, A S; Johnson, W N; Kadler, M; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Knodlseder, J; Kocian, M L; Kuss, M; Lande, J; Latronico, L; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Max-Moerbeck, W; Mazziotta, M N; McConville, W; McEnery, J E; Meurer, C; Michelson, P F

    2009-01-01

    (Abridged) We have conducted a detailed investigation of the broad-band spectral properties of the \\gamma-ray selected blazars of the Fermi LAT Bright AGN Sample (LBAS). By combining our accurately estimated Fermi gamma-ray spectra with Swift, radio, infra-red, optical and other hard X-ray/gamma-ray data, collected within three months of the LBAS data taking period, we were able to assemble high-quality and quasi-simultaneous Spectral Energy Distributions (SED) for 48 LBAS blazars.The SED of these gamma-ray sources is similar to that of blazars discovered at other wavelengths, clearly showing, in the usual Log $\

  1. Removing lateral chromatic aberration in bright field optical microscopy.

    Science.gov (United States)

    Guzmán-Altamirano, Miguel; Gutiérrez-Medina, Braulio

    2015-06-01

    We present an efficient alternative to remove lateral chromatic aberration (LCA) in bright field light microscopy images. Our procedure is based on error calibration using time-sequential acquisition at different wavelengths, and error correction through digital image warping. Measurement of the displacements of fiducial marks in the red and green images relative to blue provide calibration factors that are subsequently used in test images to realign color channels digitally. We demonstrate quantitative improvement in the position and boundaries of objects in target slides and in the color content and morphology of specimens in stained biological samples. Our results show a reduction of LCA content below the 0.1% level.

  2. Hi-C Observations of Sunspot Penumbral Bright Dots

    OpenAIRE

    Alpert, Shane E.; Tiwari, Sanjiv K.; Moore, Ronald L.; Winebarger, Amy R.; Savage, Sabrina L.

    2016-01-01

    We report observations of bright dots (BDs) in a sunspot penumbra using High Resolution Coronal Imager (Hi-C) data in 193 \\AA\\ and examine their sizes, lifetimes, speeds, and intensities. The sizes of the BDs are on the order of 1\\arcsec\\ and are therefore hard to identify in the Atmospheric Imaging Assembly (AIA) 193 \\AA\\ images, which have 1.2\\arcsec\\ spatial resolution, but become readily apparent with Hi-C's five times better spatial resolution. We supplement Hi-C data with data from AIA'...

  3. On the origin of low surface-brightness galaxies

    CERN Document Server

    Antonuccio-Delogu, V

    1994-01-01

    We reconsider the problem of the origin of Low-Surface-Brightness (LSB) galaxies within the standard Cold Dark Matter (CDM) cosmological model (\\Omega =1, h=0.5). Taking into account the effect of substructure on the collapse times of low overdensity peaks, we show that the abundance of these peaks is larger than previously expected because of the dragging caused by dynamical friction induced by the presence of small-scale substructure. The number density of these shallow, low-density peaks turns out to be in good agreement with the observed overdensity of the blue LSB galaxies found during recent surveys.

  4. The UV-bright Quasar Survey (UVQS): DR1

    CERN Document Server

    Monroe, TalaWanda R; Tejos, N; Worseck, G; Hennawi, Joseph F; Schmidt, Tobias; Tumlinson, Jason; Shen, Yue

    2016-01-01

    We present the first data release (DR1) from our UV-bright Quasar Survey (UVQS) for new $z \\sim 1$ active galactic nuclei (AGN) across the sky. Using simple GALEX UV and WISE near-IR color selection criteria, we generated a list of 1450 primary candidates with $FUV 0.5$. Including a small set of observed secondary candidates, we report the discovery of 217 AGN with $FUV < 18$ mag that had no previously reported spectroscopic redshift. These are excellent potential targets for UV spectroscopy before the end of the {\\it Hubble Space Telescope} mission. The main data products are publicly released through the Mikulski Archive for Space Telescopes.

  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) 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. Single-molecule analysis of fluorescent carbon dots towards localization-based super-resolution microscopy

    Science.gov (United States)

    Verma, Navneet C.; Khan, Syamantak; Nandi, Chayan K.

    2016-12-01

    The advancement of high-resolution bioimaging has always been dependent on the discovery of bright and easily available fluorescent probes. Fluorescent carbon nanodots, an interesting class of relatively new nanomaterials, have emerged as a versatile alternative due to their superior optical properties, non-toxicity, cell penetrability and easy routes to synthesis. Although a plethora of reports is available on bioimaging using carbon dots, single-molecule-based super-resolution imaging is rare in the literature. In this study, we have systematically characterized the single-molecule fluorescence of three carbon dots and compared them with a standard fluorescent probe. Each of these carbon dots showed a long-lived dark state in the presence of an electron acceptor. The electron transfer mechanism was investigated in single-molecule as well as in ensemble experiments. The average on-off rate between the fluorescent bright and dark states, which is one of the important parameters for single-molecule localization-based super-resolution microscopy, was measured by changing the laser power. We report that the photon budget and on-off rate of these carbon dots were good enough to achieve single-molecule localization with a precision of ~35 nm.

  7. Preparation of Reactive Bright Blue Rare Earth Dyestuffs and Their Spectra Properties

    Institute of Scientific and Technical Information of China (English)

    Liu Xiaozhen; Sang Wenbin

    2004-01-01

    Reactive bright blue rare earth dyestuffs were prepared by using reactive bright blue and lanthanum oxide,praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, dysprosium oxide, erbium oxide, lutetium oxide, yttrium oxide respectively for dyeing silk cloth.The degree of dyeing of reactive bright blue praseodymium and the degree of fixation of reactive bright blue gadolinium are the biggest, and 22.9% and 7 %are increased with that of reactive bright blue respectively.The spectra of reactive bright blue rare earth and reactive bright blue were studied by UV-VIS.In 200.00 ~ 800.00 nm, reactive bright blue has four absorption peaks, reactive bright blue rare earth has three absorption peaks; in 420.00 ~ 760.00 nm, reactive bright blue has two absorption peaks at 661.50 nm and 625.50 nm, respectively, and λmax is 661.50 nm; reactive bright blue rare earth has one absorption peak at 620.50, 618.00, 622.00, 623.00, 622.50, 619.50, 619.00, 621.00, 624.00, 620.00 nm adding La3+ ,Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Dy3+, Er3+, Lu3+, Y3+respectively.

  8. Color center fluorescence and spin manipulation in single crystal, pyramidal diamond tips

    CERN Document Server

    Nelz, Richard; Opaluch, Oliver; Sonusen, Selda; Savenko, Natalia; Podgursky, Vitali; Neu, Elke

    2016-01-01

    We investigate bright fluorescence of nitrogen (NV)- and silicon-vacancy color centers in pyramidal, single crystal diamond tips which are commercially available as atomic force microscope probes. We coherently manipulate NV electronic spin ensembles with $T_2 = 7.7(3)\\,\\mu$s. Color center lifetimes in different tip heights indicate effective refractive index effects and quenching. Using numerical simulations, we verify enhanced photon rates from emitters close to the pyramid apex; a situation promising for scanning probe sensing.

  9. Color center fluorescence and spin manipulation in single crystal, pyramidal diamond tips

    Science.gov (United States)

    Nelz, Richard; Fuchs, Philipp; Opaluch, Oliver; Sonusen, Selda; Savenko, Natalia; Podgursky, Vitali; Neu, Elke

    2016-11-01

    We investigate bright fluorescence of nitrogen (NV)- and silicon-vacancy color centers in pyramidal, single crystal diamond tips, which are commercially available as atomic force microscope probes. We coherently manipulate NV electronic spin ensembles with T2 = 7.7(3) μs. Color center lifetimes in different tip heights indicate effective refractive index effects and quenching. Using numerical simulations, we verify enhanced photon rates from emitters close to the pyramid apex rendering them promising as scanning probe sensors.

  10. Paper-based solid-phase multiplexed nucleic acid hybridization assay with tunable dynamic range using immobilized quantum dots as donors in fluorescence resonance energy transfer.

    Science.gov (United States)

    Noor, M Omair; Krull, Ulrich J

    2013-08-06

    A multiplexed solid-phase nucleic acid hybridization assay on a paper-based platform is presented using multicolor immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). The surface of paper was modified with imidazole groups to immobilize two types of QD-probe oligonucleotide conjugates that were assembled in solution. Green-emitting QDs (gQDs) and red-emitting QDs (rQDs) served as donors with Cy3 and Alexa Fluor 647 (A647) acceptors. The gQD/Cy3 FRET pair served as an internal standard, while the rQD/A647 FRET pair served as a detection channel, combining the control and analytical test zones in one physical location. Hybridization of dye-labeled oligonucleotide targets provided the proximity for FRET sensitized emission from the acceptor dyes, which served as an analytical signal. Hybridization assays in the multicolor format provided a limit of detection of 90 fmol and an upper limit of dynamic range of 3.5 pmol. The use of an array of detection zones was designed to provide improved analytical figures of merit compared to that which could be achieved on one type of array design in terms of relative concentration of multicolor QDs. The hybridization assays showed excellent resistance to nonspecific adsorption of oligonucleotides. Selectivity of the two-plex hybridization assay was demonstrated by single nucleotide polymorphism (SNP) detection at a contrast ratio of 50:1. Additionally, it is shown that the use of preformed QD-probe oligonucleotide conjugates and consideration of the relative number density of the two types of QD-probe conjugates in the two-color assay format is advantageous to maximize assay sensitivity and the upper limit of dynamic range.

  11. Paper-based solid-phase nucleic acid hybridization assay using immobilized quantum dots as donors in fluorescence resonance energy transfer.

    Science.gov (United States)

    Noor, M Omair; Shahmuradyan, Anna; Krull, Ulrich J

    2013-02-05

    A paper-based solid-phase assay is presented for transduction of nucleic acid hybridization using immobilized quantum dots (QDs) as donors in fluorescence resonance energy transfer (FRET). The surface of paper was modified with imidazole groups to immobilize QD-probe oligonucleotide conjugates that were assembled in solution. Green-emitting QDs (gQDs) were FRET-paired with Cy3 acceptor. Hybridization of Cy3-labeled oligonucleotide targets provided the proximity required for FRET-sensitized emission from Cy3, which served as an analytical signal. The assay exhibited rapid transduction of nucleic acid hybridization within minutes. Without any amplification steps, the limit of detection of the assay was found to be 300 fmol with the upper limit of the dynamic range at 5 pmol. The implementation of glutathione-coated QDs for the development of nucleic acid hybridization assay integrated on a paper-based platform exhibited excellent resistance to nonspecific adsorption of oligonucleotides and showed no reduction in the performance of the assay in the presence of large quantities of noncomplementary DNA. The selectivity of nucleic acid hybridization was demonstrated by single-nucleotide polymorphism (SNP) detection at a contrast ratio of 19 to 1. The reuse of paper over multiple cycles of hybridization and dehybridization was possible, with less than 20% reduction in the performance of the assay in five cycles. This work provides an important framework for the development of paper-based solid-phase QD-FRET nucleic acid hybridization assays that make use of a ratiometric approach for detection and analysis.

  12. Synthesis and Fluorescence Spectra of Triazolylcoumarin Fluorescent Dyes

    Institute of Scientific and Technical Information of China (English)

    PENG Xian-fu; LI Hong-qi

    2009-01-01

    Much attention is devoted to fluorescent dyes especially those with potential in versatile applications. Reactions under "click" conditions between nonfluorescent 3 - azidocoumarins and terminal alkynes produced 3 -(1, 2, 3- triazol- 1 - yl)cournarins, a novel type of fluorescent dyes with intense fluorescence. The structures of the new coumarins were characterized by 1H NMR, MS, and IR spectra. Fluorescence spectra measurement demonstrated excellent fluorescence performance of the triazolylcoumarins and this click reaction is a promising candidate for bioconjugation and bioimaging applications since both azide and alkynes are quite inert to biological systems.

  13. Fluorescence nanoscopy. Methods and applications

    OpenAIRE

    Requejo-Isidro, Jose

    2013-01-01

    Fluorescence nanoscopy refers to the experimental techniques and analytical methods used for fluorescence imaging at a resolution higher than conventional, diffraction-limited, microscopy. This review explains the concepts behind fluorescence nanoscopy and focuses on the latest and promising developments in acquisition techniques, labelling strategies to obtain highly detailed super-resolved images and in the quantitative methods to extract meaningful information from them.

  14. Highly Bright White Organic Light-Emitting Diode

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ A highly bright white organic light-emitting diode (OLED) was realized by using a highly bright blue emitting layer, 1,7-diphenyl-4-biphenyl-3,5-dimethyl-l,7-dihydrodipyrazolo[3,4-b;4',3'-e]pyridine (PAP-Ph), together with a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped Alq [tris(8-hydroxyquinolinato) aluminum (Ⅲ)] layer to provide the blue, red and green emission for color mixing. With appropriate thickness control, the white-light OLED has a performance that reaches 24700 cd/m2 at 15 V, 1.93 lm/W at 6.5 V, and >300 cd/m2 at 7.7 mA/em2. The Commission Internationale de l'Eclairage (CIE) coordinates of the emitted light vary in a very small range, from (0.35, 0.34) to (0.34, 0.35), when forward voltages change from 6 to 12 V.

  15. Highly Bright White Organic Light-Emitting Diode

    Institute of Scientific and Technical Information of China (English)

    KO; C.; W.

    2001-01-01

    A highly bright white organic light-emitting diode (OLED) was realized by using a highly bright blue emitting layer, 1,7-diphenyl-4-biphenyl-3,5-dimethyl-l,7-dihydrodipyrazolo[3,4-b;4',3'-e]pyridine (PAP-Ph), together with a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped Alq [tris(8-hydroxyquinolinato) aluminum (Ⅲ)] layer to provide the blue, red and green emission for color mixing. With appropriate thickness control, the white-light OLED has a performance that reaches 24700 cd/m2 at 15 V, 1.93 lm/W at 6.5 V, and >300 cd/m2 at 7.7 mA/em2. The Commission Internationale de l'Eclairage (CIE) coordinates of the emitted light vary in a very small range, from (0.35, 0.34) to (0.34, 0.35), when forward voltages change from 6 to 12 V.  ……

  16. 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%.

  17. 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.

  18. Properties of Galaxies in the Disc Central Surface Brightness Gap

    CERN Document Server

    Sorce, Jenny G; Libeskind, Noam I

    2015-01-01

    Intermediate surface brightness (ISB) galaxies are less numerous than their counterparts at high and low surface brightness (HSB and LSB). Investigating ISB characteristics from a sample from the S4G survey, complete down to M_B=-16, we find that they have intermediate stellar, gas and baryonic masses and on average as much gas as stars. They lie on the (baryonic) Tully-Fisher relation between HSBs and LSBs, although they present a higher scatter than the latter. Their stellar to baryonic mass ratios have intermediate values unlike their condensed baryonic fractions. By comparing their environments, as classified by the eigenvalues of the velocity shear tensor of local constrained simulations, ISBs have a 5-10% probability higher (smaller) to be in sheets (filaments) with respect to HSBs and LSBs. Additionally, for galaxies in filaments (with close neighbors), the mass and mu_0 are correlated at 2.5 (2) sigma more than for those in sheets. ISBs live in regions where the divergence of the velocity field is sma...

  19. Properties of galaxies in the disc central surface brightness gap

    Science.gov (United States)

    Sorce, Jenny G.; Creasey, Peter; Libeskind, Noam I.

    2016-01-01

    Intermediate surface brightness (ISB) galaxies are less numerous than their counterparts at high and low surface brightness (HSB and LSB). Investigating ISB characteristics from a sample from the Spitzer Survey of Stellar Structure in Galaxies survey, complete down to MB = -16, we find that they have intermediate stellar, gas and baryonic masses and on average as much gas as stars. They lie on the (baryonic) Tully-Fisher relation between HSBs and LSBs, although they present a higher scatter than the latter. Their stellar to baryonic mass ratios have intermediate values unlike their condensed baryonic fractions. By comparing their environments, as classified by the eigenvalues of the velocity shear tensor of local constrained simulations, ISBs have a 5-10 per cent probability higher (smaller) to be in sheets (filaments) with respect to HSBs and LSBs. Additionally, for galaxies in filaments (with close neighbours), the mass and μ0 are correlated at 2.5 (2)σ more than for those in sheets. ISBs live in regions where the divergence of the velocity field is smaller than where HSBs and LSBs live, a result at more than 50 per cent significance. ISBs may exist as an unstable transition state between LSBs and HSBs, the low flow activity environment maximally encouraging their formation. Interaction events altering the central baryon fraction could happen at a lower rate in these less dense environment, whilst in the higher density environments the LSBs are primarily satellite galaxies, whose accretion is sufficiently constrained that it fails to promote them to HSBs.

  20. Focused ion beams using a high-brightness plasma source

    Science.gov (United States)

    Guharay, Samar

    2002-10-01

    High-brightness ion beams, with low energy spread, have merits for many new applications in microelectronics, materials science, and biology. Negative ions are especially attractive for the applications that involve beam-solid interactions. When negative ions strike a surface, especially an electrically isolated surface, the surface charging voltage is limited to few volts [1]. This property can be effectively utilized to circumvent problems due to surface charging, such as device damage and beam defocusing. A compact plasma source, with the capability to deliver either positive or negative ion beams, has been developed. H- beams from this pulsed source showed brightness within an order of magnitude of the value for beams from liquid-metal ion sources. The beam angular intensity is > 40 mAsr-1 and the corresponding energy spread is 1 Acm-2 and a spot size of 100 nm. Such characteristics of focused beam parameters, using a dc source, will immediately open up a large area of new applications. [1] P. N. Guzdar, A. S. Sharma, S. K. Guharay, "Charging of substrates irradiated by particle beams" Appl. Phys. Lett. 71, 3302 (1997). [2] S. K. Guharay, E. Sokolovsky, J. Orloff, "Characteristics of ion beams from a Penning source for focused ion beam applications" J. Vac. Sci Technol. B17, 2779 (1999).

  1. A new sample of bright galaxy pairs in UZC

    CERN Document Server

    Focardi, P; Marinoni, S; Zitelli, V

    2006-01-01

    We present a new sample of bright galaxy pairs extracted applying an objective selection code to UZC catalog.The sample is volume limited to M$_{zw}$ = -18.9 +5 log ${\\it h}$ and contains 89 galaxy pairs.We analyze the kinematical, morphological and photometrical properties of galaxies belonging to this sample. We show that velocity separation, $| \\Delta v_{r} |$, between pair members is significantly lower in spiral type (S+S) pairs than in early-type (E+E) and mixed (E+S) pairs.This indicates that truly isolated galaxy pairs are more likely to be found among S+S pairs. We show that ellipticals are rare and underluminous in B and that late spirals (T $\\ge$ 4) are overluminous. We confirm that the formation of bright ellipticals is a phenomenon linked to group/cluster environment, while galaxy-galaxy interaction may enhance blue luminosity of disk galaxies through SF phenomena. This last statement is supported by the presence of strong FIR emission from early spirals in this sample and by the high frequency o...

  2. The first world atlas of the artificial night sky brightness

    CERN Document Server

    Cinzano, P; Elvidge, C D

    2001-01-01

    We present the first World Atlas of the zenith artificial night sky brightness at sea level. Based on radiance calibrated high resolution DMSP satellite data and on accurate modelling of light propagation in the atmosphere, it provides a nearly global picture of how mankind is proceeding to envelope itself in a luminous fog. Comparing the Atlas with the U.S. Department of Energy (DOE) population density database we determined the fraction of population who are living under a sky of given brightness. About two thirds of the World population and 99% of the population in US (excluding Alaska and Hawaii) and EU live in areas where the night sky is above the threshold set for polluted status. Assuming average eye functionality, about one fifth of the World population, more than two thirds of the US population and more than one half of the EU population have already lost naked eye visibility of the Milky Way. Finally, about one tenth of the World population, more than 40% of the US population and one sixth of the E...

  3. Predicted emittance and brightness of the pseudospark electron-beam

    Energy Technology Data Exchange (ETDEWEB)

    Pitchford, L.C. [Univ. Paul Sabatier, Toulouse (France). Centre de Physique Atomique

    1995-06-01

    The emittance /and brightness of the electron beam generated during the hollow cathode phase of pseudospark operation are calculated using the two-dimensional hybrid fluid-particle model previously developed to study the time and space development of the plasma in a pseudospark discharge. Two distinct energy components exist in the electron beam; a high-energy component with an energy equivalent to the full discharge voltage and another, broad, low-energy component. In the 100 ns following breakdown and for the conditions of the calculations, the emittance of the high energy component decreases by an order of magnitude and the brightness of the high energy component reaches almost 10{sup 10} A/m{sup 2} rad{sub 2}. This work demonstrates the feasibility of using the model to guide the optimization of the pseudospark electron beam properties and shows that the optimum beam properties are achieved after the plasma has filled the hollow cathode and begun to expand radially in the main gap.

  4. New low surface brightness dwarf galaxies in the Centaurus group

    CERN Document Server

    Müller, Oliver; Binggeli, Bruno

    2016-01-01

    We conducted an extensive CCD search for faint, unresolved dwarf galaxies of very low surface brightness in the whole Centaurus group region encompassing the Cen A and M 83 subgroups lying at a distance of roughly 4 and 5 Mpc, respectively. The aim is to significantly increase the sample of known Centaurus group members down to a fainter level of completeness, serving as a basis for future studies of the 3D structure of the group. Following our previous survey of 60 square degrees covering the M 83 subgroup, we extended and completed our survey of the Centaurus group region by imaging another 500 square degrees area in the g and r bands with the wide-field Dark Energy Survey Camera at the 4m Blanco telescope at CTIO. The limiting central surface brightness reached for suspected Centaurus members is $\\mu_r \\approx 29$ mag arcsec$^{-2}$, corresponding to an absolute magnitude $M_r \\approx -9.5$. The images were enhanced using different filtering techniques. We found 41 new dwarf galaxy candidates, which togethe...

  5. An Extremely Bright Echo Associated With SN 2002hh

    CERN Document Server

    Welch, D L; Campbell, Amy; Barlow, M J; Sugerman, Ben E K; Meixner, Margaret; Bank, S H R

    2007-01-01

    We present new, very late-time optical photometry and spectroscopy of the interesting Type II-P supernova, SN 2002hh, in NGC 6946. Gemini/GMOS-N has been used to acquire visible spectra at six epochs between 2004 August and 2006 July, following the evolution of the SN from age 661 to 1358 days. Few optical spectra of Type II supernovae with ages greater than one year exist. In addition, g'r'i' images were acquired at all six epochs. The spectral and photometric evolution of SN 2002hh has been very unusual. Measures of the brightness of this SN, both in the R and I bands as well as in the H-alpha emission flux, show no significant fading over an interval of nearly two years. The most straightforward explanation for this behavior is that the light being measured comes not only from the SN itself but also from an echo off of nearby dust. Echoes have been detected previously around several SNe but these echoes, at their brightest, were ~8 mag below the maximum brightness of the SN. At V~21 mag, the putative echo ...

  6. 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.

  7. Ultra Low Surface Brightness Imaging with the Dragonfly Telephoto Array

    CERN Document Server

    Abraham, Roberto G

    2014-01-01

    We describe the Dragonfly Telephoto Array, a robotic imaging system optimized for the detection of extended ultra low surface brightness structures. The array consists of eight Canon 400mm f/2.8 telephoto lenses coupled to eight science-grade commercial CCD cameras. The lenses are mounted on a common framework and are co-aligned to image simultaneously the same position on the sky. The system provides an imaging capability equivalent to a 0.4m aperture f/1.0 refractor with a 2.6 deg X 1.9 deg field of view. The system has no obstructions in the light path, optimized baffling, and internal optical surfaces coated with a new generation of anti-reflection coatings based on sub-wavelength nanostructures. As a result, the array's point spread function has a factor of ~10 less scattered light at large radii than well-baffled reflecting telescopes. The Dragonfly Telephoto Array is capable of imaging extended structures to surface brightness levels below 30 mag/arcsec^2 in 10h integrations (without binning or foregro...

  8. X-ray bright groups and their galaxies

    CERN Document Server

    Helsdon, S F; Helsdon, Stephen F.; Ponman, Trevor J.

    2002-01-01

    Combining X-ray data from the ROSAT PSPC and optical data drawn from the literature, we examine in detail the relationship between the X-ray and optical properties of X-ray bright galaxy groups. We find a relationship between optical luminosity and X-ray temperature consistent with that expected from self-similar scaling of galaxy systems, L_B \\propto T^{1.6 +/- 0.2}. The self-similar form and continuity of the L_B : T relation from clusters to groups and the limited scatter seen in this relation, implies that the star formation efficiency is rather similar in all these systems. We find that the bright extended X-ray components associated with many central galaxies in groups appear to be more closely related to the group than the galaxy itself, and we suggest that these are group cooling flows rather than galaxy halos. In addition we find that the optical light in these groups appears to be more centrally concentrated than the light in clusters. We also use the optical and X-ray data to investigate whether ea...

  9. 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

  10. Preparation and Characterization of Highly Fluorescent, Glutathione-coated Near Infrared Quantum Dots for in Vivo Fluorescence Imaging

    Directory of Open Access Journals (Sweden)

    Yoshichika Yoshioka

    2008-10-01

    Full Text Available Fluorescent probes that emit in the near-infrared (NIR, 700-1,300 nm region are suitable as optical contrast agents for in vivo fluorescence imaging because of low scattering and absorption of the NIR light in tissues. Recently, NIR quantum dots (QDs have become a new class of fluorescent materials that can be used for in vivo imaging. Compared with traditional organic fluorescent dyes, QDs have several unique advantages such as size- and composition-tunable emission, high brightness, narrow emission bands, large Stokes shifts, and high resistance to photobleaching. In this paper, we report a facile method for the preparation of highly fluorescent, water-soluble glutathione (GSH-coated NIR QDs for in vivo imaging. GSH-coated NIR QDs (GSH-QDs were prepared by surface modification of hydrophobic CdSeTe/CdS (core/shell QDs. The hydrophobic surface of the CdSeTe/CdS QDs was exchanged with GSH in tetrahydrofuran-water. The resulting GSH-QDs were monodisperse particles and stable in PBS (phosphate buffered saline, pH = 7.4. The GSH-QDs (800 nm emission were highly fluorescent in aqueous solutions (quantum yield = 22% in PBS buffer, and their hydrodynamic diameter was less than 10 nm, which is comparable to the size of proteins. The cellular uptake and viability for the GSH-QDs were examined using HeLa and HEK 293 cells. When the cells were incubated with aqueous solutions of the GSH-QDs (10 nM, the QDs were taken into the cells and distributed in the perinuclear region of both cells. After 12 hrs incubation of 4 nM of GSH-QDs, the viabilities of HeLa and HEK 293 cells were ca. 80 and 50%, respectively. As a biomedical utility of the GSH-QDs, in vivo NIRfluorescence imaging of a lymph node in a mouse is presented.

  11. A novel ratiometric fluorescent probe based on 1, 8-naphthalimide for the detection of Ho3 + and its bioimaging

    Science.gov (United States)

    Zhang, Huifang; Liu, Tao; Yin, Caixia; Wen, Yin; Chao, Jianbin; Zhang, Yongbin; Huo, Fangjun

    2017-03-01

    A ratiometric fluorescent probe for the detection of Ho3 + in DMSO-aqueous medium was designed and synthesized based on 1, 8-naphthalimide. The probe displayed response to Ho3 + with a fluorescence decrease at 512 nm and enhancement at 480 nm, accompanying with a distinct fluorescence change from bright yellow-green to cyan. Besides, the probe exhibited a lower detection limit (6 × 10- 8 M) and could be used in intracellular fluorescence imaging. To the best of the knowledge, it was the first ratiometric fluorescent probe for Ho3 + detection. This probe was expected to be a useful tool for further elucidating the roles of Ho3 + in materials, biology and environment.

  12. Fluorescent Cy5 silica nanoparticles for cancer cell imaging

    Science.gov (United States)

    O'Connell, Claire; Nooney, Robert I.; Glynn, MacDara; Ducree, Jens; McDonagh, Colette

    2015-08-01

    Cancer is a leading cause of death worldwide, with metastasis responsible for the majority of cancer-related deaths. Circulating tumour cells (CTCs) play a central role in metastasis. Fluorescent silica particles (NPs), of diameter ~50 nm which contain a large concentration of Cy5 dye molecules and are extremely bright, have been developed to detect these rare CTCs. Due to this brightness, the particles have superior performance compared to single Cy5 dye molecule labels, for detecting cancer cells. Fluorescence measurements show that the NPs are almost 100 times brighter than the free dye. They do not photo bleach as readily and, due to the biocompatible silica surface, they can be chemically modified, layer-by-layer, in order to bind to cells. The choice of these chemical layers, in particular the NP to antibody linker, along with the incubation period and type of media used in the incubation, has a strong influence on the specific binding abilities of the NPs. In this work, NPs have been shown to selectively bind to the MCF-7 cell line by targeting epithelial cellular adhesion molecule (EpCAM) present on the MCF-7 cell membrane by conjugating anti-EpCAM antibody to the NP surface. Results have shown a high signal to noise ratio for this cell line in comparison to a HeLa control line. NP attachment to cells was verified qualitatively with the use of fluorescence microscopy and quantitatively using image analysis methods. Once the system has been optimised, other dyes will be doped into the silica NPs and their use in multiplexing will be investigated.

  13. Improving sodium laser guide star brightness by polarization switching

    Science.gov (United States)

    Fan, Tingwei; Zhou, Tianhua; Feng, Yan

    2016-01-01

    Optical pumping with circularly polarized light has been used to enhance the brightness of sodium laser guide star. But the benefit is reduced substantially due to the precession of sodium atoms in geomagnetic field. Switching the laser between left and right circular polarization at the Larmor frequency is proposed to improve the return. With ESO’s laser guide star system at Paranal as example, numerical simulation shows that the return flux is increased when the angle between geomagnetic field and laser beam is larger than 60°, as much as 50% at 90°. The proposal is significant since most astronomical observation is at angle between 60° and 90° and it only requires a minor addition to the delivery optics of present laser system. PMID:26797503

  14. Sharp and Bright Photoluminescence Emission of Single Crystalline Diacetylene Nanoparticles

    CERN Document Server

    Kima, Seokho; Kima, Hyeong Tae; Cuic, Chunzhi; Park, Dong Hyuk

    2016-01-01

    Amorphous nanoparticles (NPs) of diacetylene (DA) molecules were prepared by using a reprecipitation method. After crystallization through solvent-vapor annealing process, the highly crystalline DA NPs show different structural and optical characteristics compared with the amorphous DA NPs. The single crystal structure of DA NPs was confirmed by high-resolution transmission electron microscopy (HR-TEM) and wide angle X-ray scattering (WAXS). The luminescence color and photoluminescence (PL) characteristics of the DA NPs were measured using color charge-coupled device (CCD) images and high-resolution laser confocal microscope (LCM). The crystalline DA NPs emit bright green light emission compared with amorphous DA NPs and the main PL peak of the crystalline DA NPs exhibits relative narrow and blue shift phenomena due to enhanced interaction between DA molecular in the nano-size crystal structure.

  15. Fundamental Photoemission Brightness Limit from Disorder Induced Heating

    CERN Document Server

    Maxson, Jared; Coleman-Smith, Christopher; Wan, Weishi; Padmore, Howard

    2013-01-01

    We determine the limit of the highest achievable photoemitted electron brightness, due to heating just after emission into vacuum, applicable to both relativistic and nonrelativistic photoelectron production. This heating is due to poorly screened Coulomb interactions equivalent to disorder induced heating seen in ultracold neutral plasmas. Owing to the multi-scale nature of the initial interactions of such systems, an N-body tree algorithm is used to compute the universal scaling of the disorder induced heating in fully contained bunches, and is shown to agree well with a simple model utilizing the tabulated correlated energy of one component plasmas. We also present simulations for beams undergoing Coulomb explosion at the photocathode, and demonstrate that both the temperature growth and subsequent cooling must be characterized by correlated effects, as well as correlation-frozen dynamics. In either case, the induced temperature is found to be of several meV for typical photoinjector beam densities, a sign...

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

    Energy Technology Data Exchange (ETDEWEB)

    RAO, T.; BEN-ZVI, I.; BURRILL, A.; CHANG, X.; GRIMES, J.; RANK, J.; SEGALOV, Z.; SMEDLEY, J.

    2005-09-20

    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{sup 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.

  17. Bright Summer Afternoon on the Mars Utopian Planitia

    Science.gov (United States)

    1976-01-01

    A UTOPIAN BRIGHT SUMMER AFTERNOON ON MARS--Looking south from Viking 2 on September 6, the orange-red surface of the nearly level plain upon which the spacecraft sits is seen strewn with rocks as large as three feet across. Many of these rocks are porous and sponge-like, similar to some of Earth's volcanic rocks. Other rocks are coarse-grained such as the large rock at lower left. Between the rocks, the surface is blanketed with fine-grained material that, in places, is piled into small drifts and banked against some of the larger blocks. The cylindrical mast with the orange cable is the low-gain antenna used to receive commands from Earth.

  18. Coupling and stability of bright holographic soliton parirs

    Institute of Scientific and Technical Information of China (English)

    Liu Jin-Song; Hao Zhong-Hua

    2004-01-01

    The coupling effect and stability property of symmetric bright holographic soliton pairs have been investigated numerically. Results show that when any one of the two solitary beams from a pair is perturbed in amplitude or width,both beams will be affected by such a perturbation via the coupling effect between the beams, thus resulting in both beams propagating in the medium without a constant shape; however, these two solitary beams are still stable against small perturbations. When both solitary beams from a pair are perturbed simultaneously in amplitude, for some given absolute values of the perturbations, the two beams are stable against these perturbations if both beams are perturbed with the same sign, whereas are unstable with the different signs. When the two beams are simultaneously perturbed in width, both beams exhibit their stability property similar to that when only one beam is perturbed no matter whether both perturbations have the same or different signs.

  19. Overview on production and dynamics of high brightness beams

    Energy Technology Data Exchange (ETDEWEB)

    Serafini, L. [INFN-Milano and UCLA Dept. of Physics and Astronomy, 405 Hilgard Ave., Los Angeles, California 90095-1547 (United States)

    1997-02-01

    The advent of laser driven RF Photoinjectors has raised the interest in the beam dynamics associated with intense, quasi-laminar, space charge dominated electron beams: the relevant phenomena observed in such a new regime of beam physics are presented and discussed in this paper. Most of the emphasis is focused on the analysis of the so called emittance correction technique, which is applied in the operation of RF guns in order to enhance the performances of these devices in terms of the attainable beam brightness, i.e., minimizing the beam emittance. A fully analytical description of this process is presented, based on an envelope equation treatment which leads to the concept of {ital invariant envelope}. The implications of such a concept are discussed and specific examples are given to compare the analytical predictions to the results of numerical simulations. {copyright} {ital 1997 American Institute of Physics.}

  20. The Stability of F-star Brightness on Century Timescales

    CERN Document Server

    Lund, Michael B; Stassun, Keivan G; Hippke, Michael; Angerhausen, Daniel

    2016-01-01

    The century-long photometric record of the DASCH project provides a unique window into the variability of stars normally considered to be photometrically inactive. In this paper, we look for long-term trends in the brightness of F stars, with particular attention to KIC 8462852,an F3 main sequence star that has been identified as significant short-term variability according to Kepler observations. Although a simple search for variability suggests long-term dimming of a number of F stars, we find that such trends are artifacts of the 'Menzel Gap' in the DASCH data. That includes the behavior of KIC 8462852, which we believe is consistent with constant flux over the full duration of observations. We do, however, present a selection of F stars thatdo have significant photometric trends, even after systematics are taken into account.

  1. Do Baryons Alter the Halos of Low Surface Brightness Galaxies?

    CERN Document Server

    de Naray, Rachel Kuzio

    2011-01-01

    High-quality observations of dark matter-dominated low surface brightness (LSB) galaxies indicate that, in contrast to the triaxial, centrally-concentrated cuspy halos formed in collisionless simulations of halo assembly, these galaxies reside in round, roughly constant density cored halos. In order to reconcile these data with galaxy formation in the context of LCDM, processes that alter the shape and density structure of the inner halo are required. We compile observational properties of LSB galaxies to evaluate the plausibility that a previously higher baryonic mass content and feedback from star formation can modify the dark matter halos of these galaxies. We also compare the properties of bulgeless disk galaxies formed in recent simulations to the LSB galaxy sample. We find that observational constraints on LSB galaxy star formation histories, structure, and kinematics make it difficult for baryonic physics to sphericalize and decrease the central density of the dark matter halos of LSB galaxies.

  2. 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.

  3. Optical Spectrophotometric Monitoring of Fermi/LAT Bright Sources

    CERN Document Server

    Patiño-Álvarez, V; León-Tavares, J; Valdés, J R; Carramiñana, A; Carrasco, L; Torrealba, J

    2013-01-01

    We describe an ongoing optical spectrophotometric monitoring program of a sample of Fermi/LAT bright sources showing prominent and variable {\\gamma}-ray emission, with the 2.1m telescope at Observatorio Astrof\\'isico Guillermo Haro (OAGH) located in Cananea, Sonora, M\\'exico. Our sample contains 11 flat spectrum radio quasars (FSRQ) and 1 Narrow Line Seyfert 1 (NLSy1) galaxy. Our spectroscopic campaign will allow us to study the spectroscopic properties (FWHM, EW, flux) of broad-emission lines in the optical (e.g. H{\\beta}) and mid-UV (e.g. Mg II {\\lambda}2800) regimes, depending on the redshift of the source. The cadence of the broad emission lines monitoring is about five nights per month which in turn will permit us to explore whether there is a correlated variability between broad emission line features and high levels of {\\gamma}-ray emission.

  4. High Brightness Proton Beams for LHC: Needs and Means

    CERN Document Server

    Benedikt, Michael; High Energy High Intensity Hadron Beams (HHH 2004)

    2005-01-01

    Experiments [1, 2] have proven that the LHC injector chain can deliver a proton beam with the nominal characteristics (bunch intensity Nb=1.15E11 protons per bunch (ppb) in normalised rms transverse emittances of 3.5 mm.mrad), but cannot reach the ultimate performance (1.7E11 ppb in the same emittances). Moreover, in the longer term, an even higher beam brightness is required by all methods considered for increasing the LHC luminosity beyond the present ultimate level. Improvements and/or new processes are therefore needed, especially in the low energy accelerators. A number of solutions have already been imagined for the PS complex that involve new linac(s) or/and sophisticated beam gymnastics. The present capabilities and limitations of the accelerator chain are described. The needs of the possible LHC luminosity upgrades are outlined, the proposed improvements are explained and their features and performance are compared.

  5. The dearth of nuclear star clusters in bright galaxies

    Science.gov (United States)

    Arca-Sedda, M.; Capuzzo-Dolcetta, R.; Spera, M.

    2016-03-01

    We investigate the interaction of a massive globular cluster (GC) with a super massive black hole (SMBH), located at the centre of its host galaxy, by means of direct N-body simulations. The results show that tidal distortions induced by the stellar background and the SMBH act on a time shorter than that of dynamical friction decay for a 106 M⊙ GC whenever the SMBH mass exceeds ˜108 M⊙. This implies an almost complete dissolution of the infalling GC before it reaches the inner region (≲5 pc) of the parent galaxy. The generalization of this result to a larger sample of infalling GCs shows that such destructive process may prevent the formation and growth of a bright galactic nucleus. Another interesting, serendipitous, result we obtained is that the close interaction between the SMBH and the GC produces a `wave' of stars that escape from the cluster and, in a fraction, even from the whole galaxy.

  6. 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.

  7. High Brightness Plasmon-Enhanced Nanostructured Gold Photoemitters

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yu; Joly, Alan G.; Kong, Lingmei; El-Khoury, Patrick Z.; Hess, Wayne P.

    2014-12-30

    Plasmonic nanohole arrays are fabricated in gold thin films by focused ion beam (FIB) lithography. Subsequent heat treatment creates sub 100 nm nanometric structures including tips, rods and flakes, all localized in the nanohole array region. The combined nanohole array and nanostructured surface comprise an efficient photoemitter. High brightness photoemission is observed from this construct using photoemission electron microscopy (PEEM), following 780 nm femtosecond (fs) laser irradiation. By comparing our observables to results of finite difference time domain (FDTD) calculations, we demonstrate that photoemission from the sub-100 nm structures is enhanced in the region of propagating surface plasmons launched from the nanohole arrays. Additionally, by tuning hole diameter and separation in the nanohole array, the photoemission intensity of nanostructured photoemitters can be controlled. We observe a photoemission enhancement of over 108, relative to photoemission from the flat region of the gold substrate at laser intensities well below the ablation threshold.

  8. 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

  9. Homogeneous plate based antibody internalization assay using pH sensor fluorescent dye.

    Science.gov (United States)

    Nath, Nidhi; Godat, Becky; Zimprich, Chad; Dwight, Stephen J; Corona, Cesear; McDougall, Mark; Urh, Marjeta

    2016-04-01

    Receptor-mediated antibody internalization is a key mechanism underlying several anti-cancer antibody therapeutics. Delivering highly toxic drugs to cancer cells, as in the case of antibody drug conjugates (ADCs), efficient removal of surface receptors from cancer cells and changing the pharmacokinetics profile of the antibody drugs are some of key ways that internalization impacts the therapeutic efficacy of the antibodies. Over the years, several techniques have been used to study antibody internalization including radiolabels, fluorescent microscopy, flow cytometry and cellular toxicity assays. While these methods allow analysis of internalization, they have limitations including a multistep process and limited throughput and are generally endpoint assays. Here, we present a new homogeneous method that enables time and concentration dependent measurements of antibody internalization. The method uses a new hydrophilic and bright pH sensor dye (pHAb dye), which is not fluorescent at neutral pH but becomes highly fluorescent at acidic pH. For receptor mediated antibody internalization studies, antibodies against receptors are conjugated with the pHAb dye and incubated with the cells expressing the receptors. Upon binding to the receptor, the dyes conjugated to the antibody are not fluorescent because of the neutral pH of the media, but upon internalization and trafficking into endosomal and lysosomal vesicles the pH drops and dyes become fluorescent. The enabling attributes of the pHAb dyes are the hydrophilic nature to minimize antibody aggregation and bright fluorescence at acidic pH which allows development of simple plate based assays using a fluorescent reader. Using two different therapeutic antibodies--Trastuzumab (anti-HER2) and Cetuximab (anti-EGFR)--we show labeling with pHAb dye using amine and thiol chemistries and impact of chemistry and dye to antibody ration on internalization. We finally present two new approaches using the pHAb dye, which will be

  10. Carmencita, The CARMENES Input Catalogue of Bright, Nearby M Dwarfs

    Science.gov (United States)

    Caballero, J. A.; Cortés-Contreras, M.; Alonso-Floriano, F. J.; Montes, D.; Quirrenbach, A.; Amado, P. J.; Ribas, I.; Reiners, A.; Abellan, F. J.; Béjar, V. J. S.; Brinkmöller, M.; Czesla, S.; Dorda, R.; Gallardo, I.; González-Álvarez, E.; Hidalgo, D.; Holgado, G.; Jeffers, S. V.; Kim, M.; Klutsch, A.; Lamert, A.; Llamas, M.; López-Santiago, J.; Martínez-Rodríguez, H.; Morales, J. C.; Mundt, R.; Passegger, V. M.; Schöfer, P.; Seifert, W.; Zechmeister, M.

    2016-08-01

    CARMENES, the brand-new, Spanish-German, two-channel, ultra-stabilised, high-resolution spectrograph at the 3.5 m Calar Alto telescope, started its science survey on 01 Jan 2016. In one shot, it covers from 0.52 to 1.71 μm with resolution R = 94,600 (λ 0.96 μm). During guaranteed time observations, CARMENES carries out the programme for which the instrument was designed: radial-velocity monitoring of bright, nearby, low-mass dwarfs with spectral types be- tween M0.0 V and M9.5 V. Carmencita is the "CARMEN(ES) Cool dwarf Information and daTa Archive", our input catalogue, from which we select the about 300 targets being observed during guaranteed time. Besides that, Carmencita is perhaps the most comprehensive database of bright, nearby M dwarfs ever built, as well as a useful tool for forthcoming exo-planet hunters: ESPRESSO, HPF, IRD, SPIRou, TESS or even PLATO. Carmencita contains dozens of parameters measured by us or compiled from the literature for about 2,200 M dwarfs in the solar neighbourhood brighter than J = 11.5 mag: accurate coordinates, spectral types, photometry from ultraviolet to mid-infrared, parallaxes and spectro-photometric distances, rotational and radial velocities, Hα pseudo-equivalent widths, X-ray count rates and hardness ratios, close and wide multiplicity data, proper motions, Galactocentric space velocities, metallicities, full references, homogeneously derived astrophysical parameters, and much more. In my talk at Cool Stars 19, I explained how we build Carmencita standing on the shoulders of giants and observing with 2-m class telescopes, and produce a dozen MSc theses and several PhD theses in the process (http://carmenes.caha.es).

  11. Multiple dark-bright solitons in atomic Bose-Einstein condensates

    Energy Technology Data Exchange (ETDEWEB)

    Yan, D.; Kevrekidis, P. G. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003-4515 (United States); Chang, J. J.; Hamner, C.; Engels, P. [Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164 (United States); Achilleos, V.; Frantzeskakis, D. J. [Department of Physics, University of Athens, Panepistimiopolis, Zografos, GR-157 84 Athens (Greece); Carretero-Gonzalez, R. [Nonlinear Dynamical Systems Group, Department of Mathematics and Statistics and Computational Science Research Center, San Diego State University, San Diego, California 92182-7720 (United States); Schmelcher, P. [Zentrum fuer Optische Quantentechnologien, Universitaet Hamburg, Luruper Chaussee 149, D-22761 Hamburg (Germany)

    2011-11-15

    Motivated by recent experimental results, we present a systematic theoretical analysis of dark-bright-soliton interactions and multiple-dark-bright-soliton complexes in atomic two-component Bose-Einstein condensates. We study analytically the interactions between two dark-bright solitons in a homogeneous condensate and then extend our considerations to the presence of the trap. We illustrate the existence of robust stationary dark-bright-soliton ''molecules,'' composed of two or more solitons, which are formed due to the competition of the interaction forces between the dark- and bright-soliton components and the trap force. Our analysis is based on an effective equation of motion, derived for the distance between two dark-bright solitons. This equation provides equilibrium positions and characteristic oscillation frequencies of the solitons, which are found to be in good agreement with the eigenfrequencies of the anomalous modes of the system.

  12. The influence of galaxy surface brightness on the mass-metallicity relation

    CERN Document Server

    Wu, Po-Feng; Tully, R Brent; Neill, J D

    2015-01-01

    We study the effect of surface brightness on the mass-metallicity relation using nearby galaxies whose gas content and metallicity profiles are available. Previous studies using fiber spectra indicated that lower surface brightness galaxies have systematically lower metallicity for their stellar mass, but the results were uncertain because of aperture effect. With stellar masses and surface brightnesses measured at WISE W1 and W2 bands, we re-investigate the surface brightness dependence with spatially-resolved metallicity profiles and find the similar result. We further demonstrate that the systematical difference cannot be explained by the gas content of galaxies. For two galaxies with similar stellar and gas masses, the one with lower surface brightness tends to have lower metallicity. Using chemical evolution models, we investigate the inflow and outflow properties of galaxies of different masses and surface brightnesses. We find that, on average, high mass galaxies have lower inflow and outflow rates rel...

  13. Herschel SPIRE Fourier Transform Spectrometer: Calibration of its Bright-source Mode

    CERN Document Server

    Lu, Nanyao; Swinyard, Bruce M; Benielli, Dominique; Fulton, Trevor; Hopwood, Rosalind; Imhof, Peter; Lim, Tanya; Marchili, Nicola; Naylor, David A; Schulz, Bernhard; Sidher, Sunil; Valtchanov, Ivan

    2014-01-01

    The Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) on board the ESA Herschel Space Observatory has two detector setting modes: (a) a nominal mode, which is optimized for observing moderately bright to faint astronomical targets, and (b) a bright-source mode recommended for sources significantly brighter than 500 Jy, within the SPIRE FTS bandwidth of 446.7-1544 GHz (or 194-671 microns in wavelength), which employs a reduced detector responsivity and out-of-phase analog signal amplifier/demodulator. We address in detail the calibration issues unique to the bright-source mode, describe the integration of the bright-mode data processing into the existing pipeline for the nominal mode, and show that the flux calibration accuracy of the bright-source mode is generally within 2% of that of the nominal mode, and that the bright-source mode is 3 to 4 times less sensitive than the nominal mode.

  14. Self-deflection of bright soliton in a separate bright-dark screening soliton pair based on higher-order space charge field

    Institute of Scientific and Technical Information of China (English)

    Zhonghua Hao(郝中华); Jinsong Liu(刘劲松)

    2003-01-01

    Based on the interaction of the separate soliton pair, the self-deflection of the bright screening soliton in a bright-dark pair is studied by taking the higher order space charge field into account. Both numerical and analytical methods are adopted to obtain the result that the higher order of space charge field can enhance the deflection process of the bright soliton and varying the peak intensity of the dark soliton can influence the self-deflection strongly. The expression of the deflection distance with the dark soliton's peak intensity is derived, and some corresponding properties of the self-deflection process are figured out.

  15. Quinoxaline-Based Polymer Dots with Ultrabright Red to Near-Infrared Fluorescence for In Vivo Biological Imaging.

    Science.gov (United States)

    Liu, Hong-Yi; Wu, Pei-Jing; Kuo, Shih-Yu; Chen, Chuan-Pin; Chang, En-Hao; Wu, Chang-Yi; Chan, Yang-Hsiang

    2015-08-19

    This article describes the design and synthesis of quinoxaline-based semiconducting polymer dots (Pdots) that exhibit near-infrared fluorescence, ultrahigh brightness, large Stokes shifts, and excellent cellular targeting capability. We also introduced fluorine atoms and long alkyl chains into polymer backbones and systematically investigated their effect on the fluorescence quantum yields of Pdots. These new series of quinoxaline-based Pdots have a fluorescence quantum yield as high as 47% with a Stokes shift larger than 150 nm. Single-particle analysis reveals that the average per-particle brightness of the Pdots is at least 6 times higher than that of the commercially available quantum dots. We further demonstrated the use of this new class of quinoxaline-based Pdots for effective and specific cellular and subcellular labeling without any noticeable nonspecific binding. Moreover, the cytotoxicity of Pdots were evaluated on HeLa cells and zebrafish embryos to demonstrate their great biocompatibility. By taking advantage of their extreme brightness and minimal cytotoxicity, we performed, for the first time, in vivo microangiography imaging on living zebrafish embryos using Pdots. These quinoxaline-based NIR-fluorescent Pdots are anticipated to find broad use in a variety of in vitro and in vivo biological research.

  16. Efficacy of a single sequence of intermittent bright light pulses for delaying circadian phase in humans

    OpenAIRE

    2004-01-01

    It has been shown in animal studies that exposure to brief pulses of bright light can phase shift the circadian pacemaker, and that the resetting action of light is most efficient during the first minutes of light exposure. In humans, multiple consecutive days of exposure to brief bright light pulses have been shown to phase shift the circadian pacemaker. The aim of the present study was to determine if a single sequence of brief bright light pulses administered during the early biological ni...

  17. Photometric indicators of visual night sky quality derived from all-sky brightness maps

    Science.gov (United States)

    Duriscoe, Dan M.

    2016-09-01

    Wide angle or fisheye cameras provide a high resolution record of artificial sky glow, which results from the scattering of escaped anthropogenic light by the atmosphere, over the sky vault in the moonless nocturnal environment. Analysis of this record yields important indicators of the extent and severity of light pollution. The following indicators were derived through numerical analysis of all-sky brightness maps: zenithal, average all-sky, median, brightest, and darkest sky brightness. In addition, horizontal and vertical illuminance, resulting from sky brightness were computed. A natural reference condition to which the anthropogenic component may be compared is proposed for each indicator, based upon an iterative analysis of a high resolution natural sky model. All-sky brightness data, calibrated in the V band by photometry of standard stars and converted to luminance, from 406 separate data sets were included in an exploratory analysis. Of these, six locations representing a wide range of severity of impact from artificial sky brightness were selected as examples and examined in detail. All-sky average brightness is the most unbiased indicator of impact to the environment, and is more sensitive and accurate in areas of slight to moderate light pollution impact than zenith brightness. Maximum vertical illuminance provides an excellent indicator of impacts to wilderness character, as does measures of the brightest portions of the sky. Zenith brightness, the workhorse of field campaigns, is compared to the other indicators and found to correlate well with horizontal illuminance, especially at relatively bright sites. The median sky brightness describes a brightness threshold for the upper half of the sky, of importance to telescopic optical astronomy. Numeric indicators, in concert with all-sky brightness maps, provide a complete assessment of visual sky quality at a site.

  18. Brightness and color of the integrated starlight at celestial, ecliptic and galactic poles

    CERN Document Server

    Nawar, S; Mikhail, J S; Morcos, A B

    2010-01-01

    From photoelectric observations of night sky brightness carried out at Abu-Simbel, Asaad et al. (1979) have obtained values of integrated starlight brightness at different Galactic latitudes. These data have been used in the present work to obtain the brightness and color of the integrated starlight at North and South Celestial, Ecliptic and Galactic Poles. The present values of the brightness are expressed in S10 units and mag/arcsec2. Our results have been compared with that obtained by other investigators using photometric and star counts techniques. The B-V and B-R have been calculated and the results are compared with that obtained by other investigators.

  19. Bright Spots on Ceres and Implications for Subsurface Composition and Structure

    Science.gov (United States)

    Stein, Nathaniel; Ehlmann, Bethany; Ammannito, Eleonora; Palomba, Ernesto; De Sanctis, Maria Cristina; Jaumann, Ralf; Nathues, Andreas; Raymond, Carol; Hiesinger, Harald; Schenk, Paul M.; Longobardo, Andrea; Dawn Team

    2016-10-01

    Images from the Dawn spacecraft show anomalously bright spots dotting Ceres' surface. Here we perform global mapping with FC data and find the spots can be classified into three geologic settings: 1) large crater floors, 2) rims/walls of craters of all sizes, or 3) the unique surface feature Ahuna Mons. There are at least 300 bright spots in total, over 200 of which are located on crater rims and walls. We examine controls on (1) and (2) as a function of crater diameter (D) and depth (d).Floor bright spots occur only in D>15 km craters, and bright spots associated with the central pit and peak complex are restricted to D>30 km. 7 of 9 craters with d>4 km (D: 70-165 km) host floor bright spots, though 30 craters with D>75 km do not contain floor bright spots, thus indicating that diameter is a weaker control on bright spot occurrence than depth. Craters with bright spots have a high d/D for their size bin, and rim/wall bright spots in craters of all sizes occur preferentially in and around the largest craters. The chief control on crater depth is presumed to be age, with shallowing due to relaxation. Thus, data suggest that previously emplaced bright materials may be removed or obscured over time via relaxation-driven burial, impact-driven lateral mixing, sublimation, or space weathering. Analyses from Dawn's VIR instrument show that some large floor bright spots are comprised of materials enriched in carbonates and other salts [e.g., 1]. The presence of bright material in many deep craters is consistent with their formation via impact-induced subsurface processes, though formation via endogenous, heterogeneously distributed subsurface processes cannot be excluded [1, 2].Here we use the Ceres production function [3] to construct a simple model in which only large (D>75 km) craters form central bright spots. These materials are then modified by later impacts. Initial results indicate that the excavation of previously emplaced bright material could explain the current

  20. Fluorescent labeling of nano-sized vesicles released by cells and subsequent quantitative and qualitative analysis by high-resolution flow cytometry.

    NARCIS (Netherlands)

    van der Vlist, E.J.; Nolte-'t Hoen, E.N.M.; Stoorvogel, W.; Arkesteijn, G.; Wauben, M.H.M.

    2012-01-01

    We provide a protocol for a high-resolution flow cytometry–based method for quantitative and qualitative analysis of individual nano-sized vesicles released by cells, as developed and previously described by our group. The method involves (i) bright fluorescent labeling of cell-derived vesicles and

  1. Photosynthetically supplemental lighting for vegetable crop production with super-bright laser diode

    Science.gov (United States)

    Hu, Yongguang; Li, Pingping; Shi, Jintong

    2007-02-01

    Although many artificial light sources like high-pressure sodium lamp, metal halide lamp, fluorescent lamp and so on are commonly used in horticulture, they are not widely applied because of the disadvantages of unreasonable spectra, high cost and complex control. Recently new light sources of light-emitting diode (LED) and laser diode (LD) are becoming more and more popular in the field of display and illumination with the improvement of material and manufacturing, long life-span and increasingly low cost. A new type of super-bright red LD (BL650, central wavelength is 650 nm) was selected to make up of the supplemental lighting panel, on which LDs were distributed with regular hexagon array. Drive circuit was designed to power it and adjust light intensity. System performance including temperature rise and light intensity distribution under different vertical/horizontal distances were tested. Photosynthesis of sweet pepper and eggplant leaf under LD was measured with LI-6400 to show the supplemental lighting effects. The results show that LD system can supply the maximum light intensity of 180 μmol/m2 •s at the distance of 50 mm below the panel and the temperature rise is little within 1 °C. Net photosynthetic rate became faster when LD system increased light intensity. Compared with sunlight and LED supplemental lighting system, LD's promotion on photosynthesis is in the middle. Thus it is feasible for LD light source to supplement light for vegetable crops. Further study would focus on the integration of LD and other artificial light sources.

  2. Bright coppertunities: efficient OLED devices with copper(I)iodide-NHetPHOS-emitters

    Science.gov (United States)

    Wallesch, Manuela; Volz, Daniel; Fléchon, Charlotte; Zink, Daniel M.; Bräse, Stefan; Baumann, Thomas

    2014-10-01

    The mass market application of OLEDs is currently hindered because i) the materials are too expensive and contain rare metals such as iridium and ii) current processing techniques are elaborate and cannot easily be up-scaled. Solution processable Cu(I)-complexes promise to solve both problems with one blow: Copper is an abundant metal, which offers new opportunities to develop materials for OLEDs. Due to their structural diversity, Cu(I) emitters allow for the design of materials with tunable properties. Beside this, it is also possible to adjust solution properties and introduce functionalities for cross-linking. The new materials feature exciting photophysical properties such as PLQY values close to unity and a tunable emission. The emission decay times are in the range of common emitters or lower, which is expected to reduce efficiency roll-off at high driving voltages. Cu(I)-complexes often feature thermally-activated delayed fluorescence (TADF). As a consequence, they can make use of triplet and singlet excitons in a process called Singlet Harvesting, which paves the way for high efficiencies. Unlike Ir(III)-complexes such as Irppy3, triplet-triplet annihilation does not occur when using Cu(I), even in very high doping concentrations. The feasibility of NHetPHOS-type Cu(I)-complexes is demonstrated as well as strategies that enable a smart crosslinking process, where the Cu(I) emitters themselves play an important role. In addition, high-brightness devices, which were operated at medium voltages, yielding 50.000 cd m-2 are shown. In a showcase example, we recently presented a device with an external quantum efficiency greater than 20% with a solution processed Cu(I)-PyrPHOS-device without using outcoupling techniques.

  3. Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon antibunching.

    Science.gov (United States)

    Wientjes, Emilie; Renger, Jan; Curto, Alberto G; Cogdell, Richard; van Hulst, Niek F

    2014-06-23

    The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demonstrate an over 500-fold fluorescence enhancement of light-harvesting complex 2 (LH2) at the single-molecule level by coupling to a gold nanoantenna. The resonant antenna produces an excitation enhancement of circa 100 times and a fluorescence lifetime shortening to ~20 ps. The radiative rate enhancement results in a 5.5-fold-improved fluorescence quantum efficiency. Exploiting the unique brightness, we have recorded the first photon antibunching of a single light-harvesting complex under ambient conditions, showing that the 27 bacteriochlorophylls coordinated by LH2 act as a non-classical single-photon emitter. The presented bright antenna-enhanced LH2 emission is a highly promising system to study energy transfer and the role of quantum coherence at the level of single complexes.

  4. Modelling of microcracks image treated with fluorescent dye

    Science.gov (United States)

    Glebov, Victor; Lashmanov, Oleg U.

    2015-06-01

    The main reasons of catastrophes and accidents are high level of wear of equipment and violation of the production technology. The methods of nondestructive testing are designed to find out defects timely and to prevent break down of aggregates. These methods allow determining compliance of object parameters with technical requirements without destroying it. This work will discuss dye penetrant inspection or liquid penetrant inspection (DPI or LPI) methods and computer model of microcracks image treated with fluorescent dye. Usually cracks on image look like broken extended lines with small width (about 1 to 10 pixels) and ragged edges. The used method of inspection allows to detect microcracks with depth about 10 or more micrometers. During the work the mathematical model of image of randomly located microcracks treated with fluorescent dye was created in MATLAB environment. Background noises and distortions introduced by the optical systems are considered in the model. The factors that have influence on the image are listed below: 1. Background noise. Background noise is caused by the bright light from external sources and it reduces contrast on the objects edges. 2. Noises on the image sensor. Digital noise manifests itself in the form of randomly located points that are differing in their brightness and color. 3. Distortions caused by aberrations of optical system. After passing through the real optical system the homocentricity of the bundle of rays is violated or homocentricity remains but rays intersect at the point that doesn't coincide with the point of the ideal image. The stronger the influence of the above-listed factors, the worse the image quality and therefore the analysis of the image for control of the item finds difficulty. The mathematical model is created using the following algorithm: at the beginning the number of cracks that will be modeled is entered from keyboard. Then the point with random position is choosing on the matrix whose size is

  5. A fluorescence scanning electron microscope

    Directory of Open Access Journals (Sweden)

    Takaaki Kanemaru

    2010-01-01

    Full Text Available Fluorescence techniques are widely used in biological research to examine molecular localization, while electron microscopy can provide unique ultrastructural information. To date, correlative images from both fluorescence and electron microscopy have been obtained separately using two different instruments, i.e. a fluorescence microscope (FM and an electron microscope (EM. In the current study, a scanning electron microscope (SEM (JEOL JXA8600 M was combined with a fluorescence digital camera microscope unit and this hybrid instrument was named a fluorescence SEM (FL-SEM. In the labeling of FL-SEM samples, both Fluolid, which is an organic EL dye, and Alexa Fluor, were employed. We successfully demonstrated that the FL-SEM is a simple and practical tool for correlative fluorescence and electron microscopy.

  6. The TALE Fluorescence Detectors

    Science.gov (United States)

    Jui, Charles

    2009-05-01

    The TALE fluorescence detectors are designed to extend the threshold for fluorescence observation by TA down to 3x10^16 eV. It will comprise two main components. The first is a set of 24 telescopes working in stereo, with an existing TA FD station at ˜6 km separation. These will cover between 3-31 degrees in elevation and have azimuthal coverage maximizing the stereo aperture in the 10^18-10^19 eV energy range. The second component consists of 15 telescopes equipped with 4m diameter mirrors and covering the sky between 31 and 73 degrees in elevation. The larger mirror size pushes the physics threshold down to 3x10^16 eV, and provides view of the shower maximum for the lower energy events. The Tower detector will cover one quadrant in azimuth and operate in hybrid mode with the TALE infill array to provide redundant composition measurements from both shower maximum information and muon-to-electron ratio.

  7. Red emitting neutral fluorescent glycoconjugates for membrane optical imaging.

    Science.gov (United States)

    Redon, Sébastien; Massin, Julien; Pouvreau, Sandrine; De Meulenaere, Evelien; Clays, Koen; Queneau, Yves; Andraud, Chantal; Girard-Egrot, Agnès; Bretonnière, Yann; Chambert, Stéphane

    2014-04-16

    A family of neutral fluorescent probes was developed, mimicking the overall structure of natural glycolipids in order to optimize their membrane affinity. Nonreducing commercially available di- or trisaccharidic structures were connected to a push-pull chromophore based on dicyanoisophorone electron-accepting group, which proved to fluoresce in the red region with a very large Stokes shift. This straightforward synthetic strategy brought structural variations to a series of probes, which were studied for their optical, biophysical, and biological properties. The insertion properties of the different probes into membranes were evaluated on a model system using the Langmuir monolayer balance technique. Confocal fluorescence microscopy performed on muscle cells showed completely different localizations and loading efficiencies depending on the structure of the probes. When compared to the commercially available ANEPPS, a family of commonly used membrane imaging dyes, the most efficient probes showed a similar brightness, but a sharper pattern was observed. According to this study, compounds bearing one chromophore, a limited size of the carbohydrate moiety, and an overall rod-like shape gave the best results.

  8. Fluorescence of ceramic color standards.

    Science.gov (United States)

    Koo, Annette; Clare, John F; Nield, Kathryn M; Deadman, Andrew; Usadi, Eric

    2010-04-20

    Fluorescence has been found in color standards available for use in calibration and verification of color measuring instruments. The fluorescence is excited at wavelengths below about 600?nm and emitted above 700?nm, within the response range of silicon photodiodes, but at the edge of the response of most photomultipliers and outside the range commonly scanned in commercial colorimeters. The degree of fluorescence on two of a set of 12 glossy ceramic tiles is enough to introduce significant error when those tiles have been calibrated in one mode of measurement and are used in another. We report the nature of the fluorescence and the implications for color measurement.

  9. The Spectral Energy Distribution of Fermi Bright Blazars

    Science.gov (United States)

    Abdo, A. A.; Ackermann, M.; Agudo, I.; Ajello, M.; Aller, H. D.; Aller, M. F.; Angelakis, E.; Arkharov, A. A.; Axelsson, M.; Bach, U.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B. M.; Bechtol, K.; Bellazzini, R.; Benitiez, E.; Berdyugin, A.; Gehrels, N.; Harding, A. K.; Hays, E.; Marshall, F.; Scargle, J. D.; Thompson, D. J.

    2010-01-01

    We have conducted a detailed investigation of the broadband spectral properties of the gamma-ray selected blazars of the Fermi LAT Bright AGN Sample (LBAS). By combining our accurately estimated Fermi gamma-ray spectra with Swift, radio, infra-red, optical, and other hard X-ray /gamma-ray data, collected within 3 months of the LBAS data taking period, we were able to assemble high-quality and quasi-simultaneous spectral energy distributions (SED) for 48 LBAS blazars. The SED of these gamma-ray sources is similar to that of blazars discovered at other wavelengths, clearly showing, in the usual log v-log v Fv representation, the typical broadband spectral signatures normally attributed to a combination of low-energy synchrotron radiation followed by inverse Compton emission of one or more components. We have used these SED to characterize the peak intensity of both the low- and the high-energy components. The results have been used to derive empirical relationships that estimate the position of the two peaks from the broadband colors (i.e., the radio to optical, alpha(sub ro) , and optical to X-ray, alpha(sub ox), spectral slopes) and from the gamma-ray spectral index. Our data show that the synchrotron peak frequency (v(sup S) (sub peak)) is positioned between 10(exp 12.5) and 10(exp 14) Hz in broad-lined flat spectrum radio quasars (FSRQs) and between 10(exp 13) and 10(exp 17) Hz in featureless BL Lacertae objects. We find that the gamma-ray spectral slope is strongly correlated with the synchrotron peak energy and with the X-ray spectral index, as expected at first order in synchrotron-inverse Compton scenarios. However, simple homogeneous, one-zone, synchrotron self-Compton (SSC) models cannot explain most of our SED, especially in the case of FSRQs and low energy peaked (LBL) BL Lacs. More complex models involving external Compton radiation or multiple SSC components are required to reproduce the overall SED and the observed spectral variability. While more than

  10. Compositional differences among Bright Spots on the Ceres surface

    Science.gov (United States)

    Palomba, Ernesto; Longobardo, Andrea; De Sanctis, Maria Cristina; Stein, Nathaniel; Ehlmann, Bethany; Ammannito, Eleonora; Giacomo Carrozzo, Filippo; Raponi, Andrea; Ciarniello, Mauro; Frigeri, Alessandro; Capria, Maria Teresa; Tosi, Federico; Zambon, Francesca; Fonte, Sergio; Giardino, Marco; Capaccioni, Fabrizio; Raymond, Carol; Russell, Christopher T.; VIR-Dawn Team

    2016-10-01

    The Dawn mission detected areas of a relatively higher albedo defined as "bright spots" (BS) on the Ceres surface. The most important member of this family is represented by the Occator crater and more precisely by the two very high albedo areas located on the crater floor.In this work we identified BS on Ceres by using the hyperspectral data produced by the VIR instrument [1]. We used an approach similar to the one used for Vesta [2], identifying 38 BS. More than 80% of BS's are related to features generated by impacts. The remaining cases concern diffused material, spots, a scarp and the Ahuna Mons.The absolute value of the albedo at 1.2 um of BS is approximately 40% larger than the average Ceres albedo, with the two Occator bright areas being by far the brightest on the entire surface.The general spectral behavior with respect to surroundings includes increased band depths at 2.7, 3.4 and 4.0 um. This is clear especially for the Occator region [3], but is a common behavior also for other BS. This strongly supports that carbonates, producing the 3.4 and 4.0 um absorption band, are the main brightening agent in these regions [3]. Another common trend is the shallowing of the 3.05 um band [4], related to ammonia.Increase of the two carbonate band depths is always evident in BS; this is not always true for the 2.7 um band. Six BS show a 2.7 um band depth decrease with respect to the surroundings. These six BS correspond to impact features; therefore, a possible interpretation is a dehydration due to the impact.Four other BS show instead a 3.05 um band deepening, contrarily to the common BS behavior. The interpretation of this observation is in progress.AcknowledgementsVIR was funded and coordinated by ASI, and built by SELEX ES, with the scientific leadership of IAPS-INAF, Rome, Italy, and is operated by IAPS-INAF, Rome, Italy. Support of the Dawn Teams is gratefully acknowledged.References[1] De Sanctis, M.C. et al., 2011, SSR, 163, 329[2] Palomba, E., et al. 2014

  11. The molecular gas associated with the Orion bright bar

    Science.gov (United States)

    Omodaka, Toshihiro; Hayashi, Masahiko; Hasegawa, Telsuo; Hayashi, Saeko S.

    1994-07-01

    Detailed studies of the shocked region associated with the Orion bright bar are presented. The millimeter wave spectral lines of (12)CO (J = 1-0), (13)CO (J = 1-0), CS (J = 2-1), HCO(+) (J = 1-0), and H51 alpha have been observed across the bright bar. The intensity of all the molecular species shows a rapid increase close to the ionization front and a significant falloff at a distance of approximately 50 sec farther out from it. This suggests the existence of a layer of dense molecular gas just outside the ionization front. This layer has a velocity redshifted by 1-2 km s-1 relative to the ambient molecular cloud, which can be due to acceleration by thermal and kinetic pressure from the H II region or due to a passage of a shock. The high-density molecular layer associated with the bar is probably a shock-compressed layer driven by the ionization front of M42. A multitransitional anaylsis of the CS emission shows that the H2 volume density of the molecular gas is larger than that of the ambient gas by a factor of 3. The apparent density enhancement of a factor of 3 in the shocked gas is too small for a radiative shock in a homogeneous medium; density inhomgeneities or clumpiness in the pre- and postshocked layer may account for this apparently small compression ratio. This layer is exposed to intense UV radiation from the Trapezium stars and a photodissocited region is formed between neutral layer and the ionization front. The similarity in distribution of the thermally excited H2 emissions arising from shock fronts and or dense phtotodissociation regions and the millimeter-wave molecular line emissions originating from cooled shock-compressed regions also supports the idea of homogeneity or clumpiness is the shocked cloud. The gas temperature of this shocked layer is about 100 K and is very high compared with other molecular clouds without an embedded heat source. Both shock heating and radiative heating may contribute to maintain this high temperature.

  12. Rapid Brightness Variations as a Tool to Enhance Satellite Detectability

    Science.gov (United States)

    Laas-Bourez, Myrtille; Klotz, Alain; Ducrotte, Etienne; Boer, Michel; Blanchet, Gwendoline

    2009-03-01

    To preserve the space environment for future generations and ensure the safety of space missions, we have to improve our knowledge of the debris at all altitudes. Since 2004, we have started to observe and study satellites and debris on the geostationary orbit. We use a network of robotic telescopes called TAROT (Télescopes Action Rapide pour les Objets Transitoires - Rapid Action Telescope for Transient Objects) which are located in France and Chile. This system processes the data in real time. Its wide field of view is useful for detection, systematic survey and to follow both catalogued and uncatalogued objects. The TAROTs are 25 cm telescopes with a wide field of view of 1.86deg x 1.86deg. It can detect objects up to 17th magnitude with an integration time of 30 seconds, corresponding to an object of 50cm in the geostationary belt with a 0.2 albedo. Tiny debris are also dangerous for space mission and satellites. To detect them, we need either to increase the TAROT sensitivity or to observe them in optimal light conditions.Last year we detected very important magnitude variations from several geostationary satellites during observations close to equinoxes. The brightness of a geostationary satellite evolves during the night and during the year, depending on the angle between the observer, the satellite and the sun. Geostationary satellites will be brighter near March 1st and of October 10th, at their exit of the shade. In this period the sun crosses the equatorial plan of the Earth, the enlightened surface will reach a maximum during a limited periods of time (about 30 minutes), provoking a short, bright flash. This phenomenon is used in two ways: first, it allows to detect smaller objects, which are usually below the detection limit, enhancing the sensitivity of the survey. Secondly, for longer objects the light curve during and outside the °ash contains information on the object intrinsic geometry and reflectivity. In this paper we discuss how the various

  13. 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.

  14. Fluorescent core-shell silica nanoparticles: towards "Lab on a Particle" architectures for nanobiotechnology.

    Science.gov (United States)

    Burns, Andrew; Ow, Hooisweng; Wiesner, Ulrich

    2006-11-01

    Novel nanoscale fluorescent materials are integral to the progress of emergent fields such as nanobiotechnology and facilitate new research in a variety of contexts. Sol-gel derived silica is an excellent host material for creating fluorescent nanoparticles by the inclusion of covalently-bound organic dyes. Significant enhancements in the brightness and stability of organic dye emission can be achieved for silica-based core-shell nanoparticle architectures at length scales down to tens of nanometers with narrow size distributions. This tutorial review will highlight these findings and describe the evolution of the fluorescent core-shell silica nanoparticle concept towards integration of multiple functionalities including mesoporosity, metal nanoshells and quantitative chemical sensing. These developments point towards the development of "lab on a particle" architectures with promising prospects for nanobiotechnology, drug development and beyond.

  15. Synthesis and characterisation of highly fluorescent core-shell nanoparticles based on Alexa dyes

    Energy Technology Data Exchange (ETDEWEB)

    Natte, Kishore; Behnke, Thomas; Orts-Gil, Guillermo, E-mail: guillermo.orts-gil@bam.de; Wuerth, Christian; Friedrich, Joerg F.; Oesterle, Werner; Resch-Genger, Ute, E-mail: ute.resch@bam.de [BAM Federal Institute for Materials Research and Testing (Germany)

    2012-02-15

    Current and future developments in the emerging field of nanobiotechnology are closely linked to the rational design of novel fluorescent nanomaterials, e.g. for biosensing and imaging applications. Here, the synthesis of bright near infrared (NIR)-emissive nanoparticles based on the grafting of silica nanoparticles (SNPs) with 3-aminopropyl triethoxysilane (APTES) followed by covalent attachment of Alexa dyes and their subsequent shielding by an additional silica shell are presented. These nanoparticles were investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM) and fluorescence spectroscopy. TEM studies revealed the monodispersity of the initially prepared and fluorophore-labelled silica particles and the subsequent formation of raspberry-like structures after addition of a silica precursor. Measurements of absolute fluorescence quantum yields of these scattering particle suspensions with an integrating sphere setup demonstrated the influence of dye labelling density-dependent fluorophore aggregation on the signaling behaviour of such nanoparticles.

  16. Fluorescence dynamics of green fluorescent protein in AOT reversed micelles

    NARCIS (Netherlands)

    Uskova, M.A.; Borst, J.W.; Hink, M.A.; Hoek, van A.; Schots, A.; Klyachko, N.L.; Visser, A.J.W.G.

    2000-01-01

    We have used the enhanced green fluorescent protein (EGFP) to investigate the properties of surfactant-entrapped water pools in organic solvents (reversed micelles) with steady-state and time-resolved fluorescence methods. The surfactant used was sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and the

  17. Spectroscopy of bright quasars: emission lines and internal extinction

    CERN Document Server

    Bachev, R; Semkov, E; Mihov, B

    2008-01-01

    The main purpose of this work is to improve the existing knowledge about the most powerful engines in the Universe - quasars. Although a lot is already known, we still have only a vague idea how these engines work exactly, why they behave as they do, and what the relation is between their evolution and the evolution of their harboring galaxy. Methods we used are based on optical spectroscopy of visually bright quasars, many of which have recently been discovered as X-ray sources, but eventually missed in color-selected surveys. The spectra typically cover the 4200-7000 AA region, allowing measurements of the characteristics of the hydrogen lines, the FeII contribution, and other lines of interest. We present accurate redshift estimates and Seyfert type classification of the objects. We also show that the contribution of the host galaxy to the optical continuum is non-negligible in many cases, as is the intrinsic AGN absorption. Consequences of not correcting for those factors when estimating different quasar ...

  18. Physical characteristics of bright Class I methanol masers

    CERN Document Server

    Leurini, S; Walmsley, C M

    2016-01-01

    Class I CH$_3$OH masers trace interstellar shocks. They have received little attention mostly as a consequence of their low luminosities; this situation has changed recently and Class I masers are now routinely used as signposts of outflows. The recent detection of polarisation in Class I lines now makes it possible to obtain information on magnetic fields in shocks. We make use of newly calculated collisional rates to investigate the excitation of Class I masers and to reconcile their observed properties with model results. We performed LVG calculations with a plane-parallel slab geometry to compute the pump and loss rates which regulate the interactions of the different maser systems with the maser reservoir. We study the dependence of the pump rate, the loss rate, and the inversion efficiency of the pumping scheme of Class I masers on the physics of the gas. Bright Class I masers are mainly high-temperature high-density structures with maser emission measures corresponding to high CH$_3$OH abundances close...

  19. Half-brightness measurements of candidate radiation sensors

    Science.gov (United States)

    Williams, Stephen Alexander

    Ionizing radiation poses a significant challenge for human and robotic space missions. Practical luminescent sensors will depend heavily upon research investigating the resistance of these materials to ionizing radiation and the ability to anneal or self-heal the damage caused by such radiation. In 1951, Birks and Black experimentally showed that the luminescent efficiency of anthracene bombarded by alpha particles varies with total fluence. From 1990 to the present, we found that the Birks and Black relation describes the reduction in light emission yield for every tested luminescent material except lead phosphate glass due to proton irradiation. These results indicate that radiation produced quenching centers compete with emission for absorbed energy. The purpose of this thesis is to present new results from related luminescent materials by exposing them to a 1-3 MeV proton beam. Particular emphasis will be placed on recent measurements made with bright luminescent materials, such as zinc sulfide doped with manganese (ZnS:Mn), europium tetrakis dibenzoylmethide triethylammonium (EuD4TEA), an magnesium tetrakis dibenzoylmethide triethylammonium (MgD4TEA). This research can be used to help determine if luminescent materials can be used as a real-time sensor to detect ionizing radiation.

  20. GMRT H I study of giant low surface brightness galaxies

    Science.gov (United States)

    Mishra, A.; Kantharia, N. G.; Das, M.; Omar, A.; Srivastava, D. C.

    2017-01-01

    We present H I observations of four giant low surface brightness (GLSB) galaxies UGC 1378, UGC 1922, UGC 4422 and UM 163 using the Giant Meterwave Radio Telescope. We include H I results on UGC 2936, UGC 6614 and Malin 2 from literature. H I is detected from all the galaxies and the extent is roughly twice the optical size; in UM 163, H I is detected along a broken disc encircling the optical galaxy. We combine our results with those in literature to further understand these systems. The main results are the following: (1) the peak H I surface densities in GLSB galaxies are several times 1021 cm-2. The H I mass is between 0.3 and 4 × 1010 M⊙; dynamical mass ranges from a few times 1011 M⊙ to a few times 1012 M⊙. (2) The rotation curves of GLSB galaxies are flat to the outermost measured point with rotation velocities of the seven GLSB galaxies being between 225 and 432 km s-1. (3) Recent star formation traced by near-ultraviolet emission in five GLSB galaxies in our sample appears to be located in rings around the galaxy centre. We suggest that this could be due to a stochastic burst of star formation at one location in the galaxy being propagated along a ring over a rotation period. (4) The H I is correlated with recent star formation in five of the seven GLSB galaxies.

  1. The Secular and Rotational Brightness Variations of Neptune

    CERN Document Server

    Schmude, Richard W; Fox, Jim; Krobusek, Bruce A; Pavlov, Hristo; Mallama, Anthony

    2016-01-01

    Neptune has brightened by more than 10% during the past several decades. We report on the analysis of published Johnson-Cousins B and V magnitudes dating back to 1954 along with new U, B, V, R, Rc, I and Ic photometry that we recorded during the past 24 years. Characteristic magnitudes, colors and albedos in all seven band-passes are derived from the ensemble of data. Additionally, 25 spectra spanning 26 hours of observation on 5 nights are analyzed. The spectrophotometry demonstrates that planetary flux and albedo is inversely related to the equivalent widths of methane bands. We attribute the changes in band strength, flux and albedo to the high altitude clouds which rotate across the planet's visible disk. Bright clouds increase albedo and flux while reducing methane absorption. Synthetic V magnitudes derived from the spectroscopy also agree closely with the photometric quantities, which cross-validates the two techniques. The spectroscopic and photometric results are discussed within the framework of the ...

  2. On the weakness of disc models in bright ULXs

    CERN Document Server

    Gonçalves, A C; Goncalves, Anabela C.; Soria, Roberto

    2006-01-01

    It is sometimes suggested that phenomenological power-law plus cool disc-blackbody models represent the simplest, most robust interpretation of the X-ray spectra of bright ultraluminous X-ray sources (ULXs); this has been taken as evidence for the presence of intermediate-mass black holes (BHs) (M ~ 10^3 Msun) in those sources. Here, we assess this claim by comparing the cool disc-blackbody model with a range of other models. For example, we show that the same ULX spectra can be fitted equally well by subtracting a disc-blackbody component from a dominant power-law component, thus turning a soft excess into a soft deficit. Then, we propose a more complex physical model, based on a power-law component slightly modified at various energies by smeared emission and absorption lines from highly-ionized, fast-moving gas. We use the XMM-Newton/EPIC spectra of two ULXs in Holmberg II and NGC 4559 as examples. Our main conclusion is that the presence of a soft excess or a soft deficit depends on the energy range over ...

  3. The ROSAT All-Sky Survey Bright Source Catalogue

    CERN Document Server

    Voges, W; Boller, T; Bräuninger, H; Briel, U G; Burkert, W K A; Dennerl, K; Englhauser, J; Gruber, R; Haberl, F; Hartner, G; Hasinger, G; Pfeffermann, E; Pietsch, W; Predehl, P; Rosso, C; Schmitt, J H M M; Trümper, J E; Zimmermann, H U; Voges, Wolfgang; Aschenbach, Bernd; Boller, Thomas; Braeuninger, Heinrich; Briel, Ulrich; Burkert, Wolfgang; Dennerl, Konrad; Englhauser, Jakob; Gruber, Rainer; Haberl, Frank; Hartner, Gisela; Hasinger, Guenther; Pfeffermann, Elmar; Pietsch, Wolfgang; Predehl, Peter; Rosso, Cristina; Schmitt, Juergen H.M.M.; Truemper, Joachim; Zimmermann, Hans-Ulrich

    1999-01-01

    We present the ROSAT All-Sky Survey Bright Source Catalogue (RASS-BSC, revision 1RXS) derived from the all-sky survey performed during the first half year (1990/91) of the ROSAT mission. 18,811 sources are catalogued (i) down to a limiting ROSAT PSPC count-rate of 0.05 cts/s in the 0.1-2.4 keV energy band, (ii) with a detection likelihood of at least 15 and (iii) at least 15 source counts. The 18,811 sources underwent both an automatic validation and an interactive visual verification process in which for 94% of the sources the results of the standard processing were confirmed. The remaining 6% have been analyzed using interactive methods and these sources have been flagged. Flags are given for (i) nearby sources; (ii) sources with positional errors; (iii) extended sources; (iv) sources showing complex emission structures; and (v) sources which are missed by the standard analysis software. Broad band (0.1-2.4 keV) images are available for sources flagged by (ii), (iii) and (iv). For each source the ROSAT name...

  4. Kinematics of Magnetic Bright Features in the Solar Photosphere

    Science.gov (United States)

    Jafarzadeh, S.; Solanki, S. K.; Cameron, R. H.; Barthol, P.; Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Knölker, M.; Martínez Pillet, V.; Orozco Suárez, D.; Riethmüller, T. L.; Schmidt, W.; van Noort, M.

    2017-03-01

    Convective flows are known as the prime means of transporting magnetic fields on the solar surface. Thus, small magnetic structures are good tracers of turbulent flows. We study the migration and dispersal of magnetic bright features (MBFs) in intergranular areas observed at high spatial resolution with Sunrise/IMaX. We describe the flux dispersal of individual MBFs as a diffusion process whose parameters are computed for various areas in the quiet-Sun and the vicinity of active regions from seeing-free data. We find that magnetic concentrations are best described as random walkers close to network areas (diffusion index, γ =1.0), travelers with constant speeds over a supergranule (γ =1.9{--}2.0), and decelerating movers in the vicinity of flux emergence and/or within active regions (γ =1.4{--}1.5). The three types of regions host MBFs with mean diffusion coefficients of 130 km2 s‑1, 80–90 km2 s‑1, and 25–70 km2 s‑1, respectively. The MBFs in these three types of regions are found to display a distinct kinematic behavior at a confidence level in excess of 95%.

  5. A Compact High-Brightness Heavy-Ion Injector

    CERN Document Server

    Westenskow, Glen; Grote, D P; Halaxa, Erni; Kwan, Joe W

    2005-01-01

    To provide compact high-brightness heavy-ion beams for Heavy Ion Fusion (HIF) accelerators, we have been experimenting with merging multi-beamlets in an injector which uses an RF plasma source. In an 80-kV 20-microsecond experiment, the RF plasma source has produced up to 5 mA of Ar+ in a single beamlet. An extraction current density of 100 mA/cm2 was achieved, and the thermal temperature of the ions was below 1 eV. More than 90% of the ions were in the Ar+ state, and the energy spread from charge exchange was found to be small. We have tested at full voltage gradient the first 4 gaps of a 61-beamlet injector design. Einzel lens were used to focus the beamlets while reducing the beamlet to beamlet space charge interaction. We will report on a converging 119 multi-beamlet source. Although the source has the same optics as a full 1.6 MV injector system, the test will be carried out at 400 kV due to the test stand HV limit. We will measure the beam’s emittance after the beamlets are merged and have bee...

  6. QUASI-PERIODIC OSCILLATION OF A CORONAL BRIGHT POINT

    Energy Technology Data Exchange (ETDEWEB)

    Samanta, Tanmoy; Banerjee, Dipankar [Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India); Tian, Hui, E-mail: tsamanta@iiap.res.in, E-mail: hui.tian@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2015-06-20

    Coronal bright points (BPs) are small-scale luminous features seen in the solar corona. Quasi-periodic brightenings are frequently observed in the BPs and are generally linked with underlying magnetic flux changes. We study the dynamics of a BP seen in the coronal hole using the Atmospheric Imaging Assembly images, the Helioseismic and Magnetic Imager magnetogram on board the Solar Dynamics Observatory, and spectroscopic data from the newly launched Interface Region Imaging Spectrograph (IRIS). The detailed analysis shows that the BP evolves throughout our observing period along with changes in underlying photospheric magnetic flux and shows periodic brightenings in different EUV and far-UV images. With the highest possible spectral and spatial resolution of IRIS, we attempted to identify the sources of these oscillations. IRIS sit-and-stare observation provided a unique opportunity to study the time evolution of one footpoint of the BP as the slit position crossed it. We noticed enhanced line profile asymmetry, enhanced line width, intensity enhancements, and large deviation from the average Doppler shift in the line profiles at specific instances, which indicate the presence of sudden flows along the line-of-sight direction. We propose that transition region explosive events originating from small-scale reconnections and the reconnection outflows are affecting the line profiles. The correlation between all these parameters is consistent with the repetitive reconnection scenario and could explain the quasi-periodic nature of the brightening.

  7. Tracking Magnetic Bright Point Motions Through the Solar Atmosphere

    CERN Document Server

    Keys, P H; Jess, D B; Shelyag, S; Christian, D J; Keenan, F P

    2012-01-01

    High cadence, multi-wavelength observations and simulations are employed for the analysis of solar photospheric magnetic bright points (MBPs) in the quiet Sun. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere (ROSA) imager and the Interferometric BIdimensional Spectrometer (IBIS) at the Dunn Solar Telescope. Our analysis reveals that photospheric MBPs have an average transverse velocity of approximately 1 km/s, whereas their chromospheric counterparts have a slightly higher average velocity of 1.4 km/s. Additionally, chromospheric MBPs were found to be around 63% larger than the equivalent photospheric MBPs. These velocity values were compared with the output of numerical simulations generated using the MURaM code. The simulated results were similar, but slightly elevated, when compared to the observed data. An average velocity of 1.3 km/s was found in the simulated G-band images and an average of 1.8 km/s seen in the velocity domain at a height of 500 km above the continuum ...

  8. 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.

  9. Ultra-bright laser-driven neutron source

    Science.gov (United States)

    Roth, M.; Favalli, A.; Bagnoud, V.; Bridgewater, J.; Deppert, O.; Devlin, M.; Falk, K.; Fernndez, J.; Gautier, D.; Guler, N.; Henzlova, D.; Hornung, J.; Iliev, M.; Ianakiev, K.; Kleinschmidt, A.; Koehler, K.; Palaniyappan, S.; Poth, P.; Schaumann, G.; Swinhoe, M.; Taddeucci, T.; Tebartz, A.; Wagner, Florian; Wurden, G.

    2015-11-01

    Short-pulse laser-driven neutron sources have become a topic of interest since their brightness and yield have recently increased by orders of magnitude. Using novel target designs, high contrast - high power lasers and compact converter/moderator setups, these neutron sources have finally reached intensities that make many interesting applications possible. We present the results of two experimental campaigns on the GSI PHELIX and the LANL Trident lasers from 2015. We have produced an unprecedented neutron flux, mapped the spatial distribution of the neutron production as well as its energy spectra and ultimately used the beam for first applications to show the prospect of these new compact sources. We also made measurements for the conversion of energetic neutrons into short epithermal and thermal neutron pulses in order to evaluate further applications in dense plasma research. The results address a large community as it paves the way to use short pulse lasers as a neutron source. This can open up neutron research to a broad academic community including material science, biology, medicine and high energy density physics to universities and therefore can complement large scale facilities like reactors or particle accelerators.

  10. Suzaku observations of the low surface brightness cluster A76

    CERN Document Server

    Ota, N; Ibaraki, Y; Boehringer, H; Chon, G

    2013-01-01

    Context: We present results of Suzaku observations of a nearby galaxy cluster A76 at z=0.0395. This cluster is characterized by extremely low X-ray surface brightness and is hereafter referred to as the LSB cluster. Aims: To understand the nature and thermodynamic evolution of the LSB cluster by studying the physical properties of the hot intracluster medium in A76. Methods: We conducted two-pointed Suzaku observations of A76 and examined the global gas properties of the cluster by XIS spectral analysis. We also performed deprojection analysis of annular spectra and derived radial profiles of gas temperature, density and entropy out to approximately 850 kpc (~ 0.6 r_200) and 560 kpc (~0.4 r_200) in A76 East and A76 West, respectively. Results: The measured global temperature and metal abundance are approximately 3.3 keV and 0.24 solar, respectively. From the deprojection analysis, the entropy profile is found to be flat with respect to radius. The entropy within the central region (r < 0.2r_200) is excepti...

  11. Optical Surface Brightness Fluctuations of shell galaxies towards 100 Mpc

    CERN Document Server

    Biscardi, I; Cantiello, M; Brocato, E

    2008-01-01

    We measure F814W Surface Brightness Fluctuations (SBF) for a sample of distant shell galaxies with radial velocities ranging from 4000 to 8000 km/s. The distance at galaxies is then evaluated by using the SBF method. For this purpose, theoretical SBF magnitudes for the ACS@HST filters are computed for single burst stellar populations covering a wide range of ages (t=1.5-14 Gyr) and metallicities (Z=0.008-0.04). Using these stellar population models we provide the first $\\bar{M}_{F814W}$ versus $(F475W-F814W)_0$ calibration and we extend the previous I-band versus $(B-I)_0$ color relation to colors $(B-I)_{0}\\leq 2.0$ mag. Coupling our SBF measurements with the theoretical calibration we derive distances with a statistical uncertainty of $\\sim 8%$, and systematic error of $\\sim 6 %$. The procedure developed to analyze data ensures that the indetermination due to possible unmasked residual shells is well below $\\sim 12 %$. The results suggest that \\emph{optical} SBFs can be measured at $d \\geq 100 Mpc$ with ACS...

  12. Photometry of some neglected bright cataclysmic variables and candidates

    CERN Document Server

    Bruch, Albert

    2016-01-01

    As part of an effort to better characterize bright cataclysmic variables (CVs) which have received little attention in the past light curves of four confirmed systems (CZ Aql, BO Cet, V380 Oph and EF Tuc) and one candidate (Lib 3) are analyzed. For none of these stars time resolved photometry has been published previously. While no variability was found in the case of Lib 3, which thus cannot be confirmed as a CV, the light curves of all other targets are dominated by strong flickering. Modulations on hourly time scales superimposed on the flickering can probably be related to orbital variations in BO Cet and V380 Oph, but not in CZ Aql and EF Tuc. Variations on the time scale of 10 minutes in CZ Aql, while not yet constituting convincing evidence, together with previous suspicions of a magnetically channeled accretion flow may point at an intermediate polar nature of this star. Some properties of the flickering are quantified in an effort to enlarge the data base for future comparative flickering studies in ...

  13. Temporal development of open-circuit bright photovoltaic solitons

    Institute of Scientific and Technical Information of China (English)

    Zhang Lei; Lu Ke-Qing; Zhang Mei-Zhi; Liu Xue-Ming; Zhang Yan-Peng

    2008-01-01

    This paper investigates the temporal behaviour of open-circuit bright photovoltaic spatial solitons by using numerical techniques. It shows that when the intensity ratio of the soliton, the ratio between the soliton peak intensity and the dark irradiance, is small, the quasi-steady-state soliton width decreases monotonically with the increase of τ, where τis the parameter correlated with the time, that when the intensity ratio of the soliton is big, the quasi-steady-state soliton width decreases with the increase of τ and then increases with τ and that the formation time of the steady-state solitons is not correlated with the intensity ratio of the soliton. It finds that the local nonlinear effect increases with the photovoltaic field, which behaves as that the width of soliton beams is small and the self-focusing quasi-period is short. On the other hand, we also discuss that both the time and the temperature have an effect on the beam bending.

  14. Low and High Surface Brightness Galaxies at Void Walls

    CERN Document Server

    Ceccarelli, L; Lambas, D G; Galaz, G; Padilla, N D

    2012-01-01

    We study the relative fraction of low and high surface brightness galaxies (LSBGs and HSBGs) at void walls in the SDSS DR7. We focus on galaxies in equal local density environments. We assume that the host dark-matter halo mass (for which we use SDSS group masses) is a good indicator of local density. This analysis allows to examine the behavior of the abundance of LSBG and HSBG galaxies at a fixed local density and distinguish the large-scale environment defined by the void geometry. We compare galaxies in the field, and in the void walls; the latter are defined as the volume of void shells of radius equal to that of the void. We find a significant decrement, a factor $\\sim 4$, of the relative fraction of blue, active star-forming LSBGs in equal mass groups at the void walls and the field. This decrement is consistent with an increase of the fraction of blue, active star-forming HSBGs. By contrast, red LSBGs and HSBGs show negligible changes. We argue that these results are consistent with a scenario where L...

  15. Modelling the brightness increase signature due to asteroid collisions

    CERN Document Server

    McLoughlin, Ev; McLoughlin, Alan

    2015-01-01

    We have developed a model to predict the post-collision brightness increase of sub-catastrophic collisions between asteroids and to evaluate the likelihood of a survey detecting these events. It is based on the cratering scaling laws of Holsapple and Housen (2007) and models the ejecta expansion following an impact as occurring in discrete shells each with their own velocity. We estimate the magnitude change between a series of target/impactor pairs, assuming it is given by the increase in reflecting surface area within a photometric aperture due to the resulting ejecta. As expected the photometric signal increases with impactor size, but we find also that the photometric signature decreases rapidly as the target asteroid diameter increases, due to gravitational fallback. We have used the model results to make an estimate of the impactor diameter for the (596) Scheila collision of D=49-65m depending on the impactor taxonomy, which is broadly consistent with previous estimates. We varied both the strength regi...

  16. 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.

  17. Hi-C Observations of Sunspot Penumbral Bright Dots

    CERN Document Server

    Alpert, Shane E; Moore, Ronald L; Winebarger, Amy R; Savage, Sabrina L

    2016-01-01

    We report observations of bright dots (BDs) in a sunspot penumbra using High Resolution Coronal Imager (Hi-C) data in 193 \\AA\\ and examine their sizes, lifetimes, speeds, and intensities. The sizes of the BDs are on the order of 1\\arcsec\\ and are therefore hard to identify in the Atmospheric Imaging Assembly (AIA) 193 \\AA\\ images, which have 1.2\\arcsec\\ spatial resolution, but become readily apparent with Hi-C's five times better spatial resolution. We supplement Hi-C data with data from AIA's 193 \\AA\\ passband to see the complete lifetime of the BDs that appeared before and/or lasted longer than Hi-C's 3-minute observation period. Most Hi-C BDs show clear lateral movement along penumbral striations, toward or away from the sunspot umbra. Single BDs often interact with other BDs, combining to fade away or brighten. The BDs that do not interact with other BDs tend to have smaller displacements. These BDs are about as numerous but move slower on average than Interface Region Imaging Spectrograph (IRIS) BDs, rec...

  18. GMRT HI study of giant low surface brightness galaxies

    CERN Document Server

    Mishra, Alka; Das, M; Omar, A; Srivastava, D C

    2016-01-01

    We present HI observations of four giant low surface brightness (GLSB) galaxies UGC 1378, UGC 1922, UGC 4422 and UM 163 using the Giant Meterwave Radio Telescope (GMRT). We include HI results on UGC 2936, UGC 6614 and Malin 2 from literature. HI is detected from all the galaxies and the extent is roughly twice the optical size; in UM 163, HI is detected along a broken disk encircling the optical galaxy. We combine our results with those in literature to further understand these systems. The main results are the following: (1) The peak HI surface densities in GLSB galaxies are several times 10^21 cm^{-2} . The HI mass is between 0.3 - 4 x 10^10 M_Sun/yr, dynamical mass ranges from a few times 10^11 M_Sun/yr to a few times 10^12 M_Sun/yr. (2) The rotation curves of GLSB galaxies are flat to the outermost measured point with rotation velocities of the seven GLSB galaxies being between 225 and 432 km s^{-1}. (3) Recent star formation traced by near-ultraviolet emission in five GLSB galaxies in our sample appears ...

  19. An Ultraviolet imager to study bright UV sources

    CERN Document Server

    Mathew, Joice; Sarpotdar, Mayuresh; Sreejith, A G; Safonova, Margarita; Murthy, Jayant

    2016-01-01

    We have designed and developed a compact ultraviolet imaging payload to fly on a range of possible platforms such as high altitude balloon experiments, cubesats, space missions, etc. The primary science goals are to study the bright UV sources (mag < 10) and also to look for transients in the Near UV (200 - 300 nm) domain. Our first choice is to place this instrument on a spacecraft going to the Moon as part of the Indian entry into Google lunar X-Prize competition. The major constraints for the instrument are, it should be lightweight (< 2Kg), compact (length < 50cm) and cost effective. The instrument is an 80 mm diameter Cassegrain telescope with a field of view of around half a degree designated for UV imaging. In this paper we will discuss about the various science cases that can be performed by having observations with the instrument on different platforms. We will also describe the design, development and the current state of implementation of the instrument. This includes opto-mechanical and e...

  20. Search for bright nearby M dwarfs with Virtual Observatory tools

    CERN Document Server

    Aberasturi, M; Montesinos, B; Gálvez-Ortiz, M C; Solano, E; Martín, E L

    2014-01-01

    Using Virtual Observatory tools, we cross-matched the Carlsberg Meridian 14 and the 2MASS Point Source catalogs to select candidate nearby bright M dwarfs distributed over ~ 25,000 deg^2. Here, we present reconnaissance low-resolution optical spectra for 27 candidates that were observed with the Intermediate Dispersion Spectrograph at the 2.5m Isaac Newton Telescope (R ~ 1600). We derived spectral types from a new spectral index, R, which measures the ratio of fluxes at 7485-7015 A and 7120-7150 A. We also used VOSA, a Virtual Observatory tool for spectral energy distribution fitting, to derive effective temperatures and surface gravities for each candidate. The resulting 27 targets were M dwarfs brighter than J = 10.5 mag, 16 of which were completely new in the Northern hemisphere and 7 of which were located at less than 15 pc. For all of them, we also measured H{\\alpha} and Na I pseudo-equivalent widths, determined photometric distances, and identified the most active stars. The targets with the weakest sod...

  1. High Brightness, High Average Current Injector Development at Cornell

    CERN Document Server

    Sinclair, C K

    2005-01-01

    Cornell University is constructing a 100 mA average current, high brightness electron injector for a planned Energy Recovery Linac (ERL) hard X-ray synchrotron radiation source. This injector will employ a very high voltage DC gun with a negative electron affinity photoemission cathode. Relatively long duration electron pulses from the photocathode will be drift bunched, and accelerated to 5-15 MeV with five two-cell, 1300 MHz superconducting cavities. The total beam power will be limited to 575 kW by the DC and RF power sources. A genetic algorithm based computational optimization of this injector has resulted in simulated rms normalized emittances of 0.1 mm-mrad at 80 pC/bunch, and 0.7 mm-mrad at 1 nC/bunch. The many technical issues and their design solutions will be discussed. Construction of the gun and the SRF cavities is well underway. The schedule for completion, and the planned measurements, will be presented.

  2. Graphical Methods for Quantifying Macromolecules through Bright Field Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hang; DeFilippis, Rosa Anna; Tlsty, Thea D.; Parvin, Bahram

    2008-08-14

    Bright ?eld imaging of biological samples stained with antibodies and/or special stains provides a rapid protocol for visualizing various macromolecules. However, this method of sample staining and imaging is rarely employed for direct quantitative analysis due to variations in sample fixations, ambiguities introduced by color composition, and the limited dynamic range of imaging instruments. We demonstrate that, through the decomposition of color signals, staining can be scored on a cell-by-cell basis. We have applied our method to Flbroblasts grown from histologically normal breast tissue biopsies obtained from two distinct populations. Initially, nuclear regions are segmented through conversion of color images into gray scale, and detection of dark elliptic features. Subsequently, the strength of staining is quanti?ed by a color decomposition model that is optimized by a graph cut algorithm. In rare cases where nuclear signal is significantly altered as a result of samplepreparation, nuclear segmentation can be validated and corrected. Finally, segmented stained patterns are associated with each nuclear region following region-based tessellation. Compared to classical non-negative matrix factorization, proposed method (i) improves color decomposition, (ii) has a better noise immunity, (iii) is more invariant to initial conditions, and (iv) has a superior computing performance

  3. QUIET-SUN NETWORK BRIGHT POINT PHENOMENA WITH SIGMOIDAL SIGNATURES

    Energy Technology Data Exchange (ETDEWEB)

    Chesny, D. L.; Oluseyi, H. M. [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Orange, N. B. [OrangeWave Innovative Science, LLC, Moncks Corner, SC 29461 (United States); Champey, P. R. [Department of Optical Science and Engineering, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

    2015-12-01

    Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.

  4. Quiet-Sun Network Bright Point Phenomena with Sigmoidal Signatures

    Science.gov (United States)

    Chesny, D. L.; Oluseyi, H. M.; Orange, N. B.; Champey, P. R.

    2015-12-01

    Ubiquitous solar atmospheric coronal and transition region bright points (BPs) are compact features overlying strong concentrations of magnetic flux. Here, we utilize high-cadence observations from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to provide the first observations of extreme ultraviolet quiet-Sun (QS) network BP activity associated with sigmoidal structuring. To our knowledge, this previously unresolved fine structure has never been associated with such small-scale QS events. This QS event precedes a bi-directional jet in a compact, low-energy, and low-temperature environment, where evidence is found in support of the typical fan-spine magnetic field topology. As in active regions and micro-sigmoids, the sigmoidal arcade is likely formed via tether-cutting reconnection and precedes peak intensity enhancements and eruptive activity. Our QS BP sigmoid provides a new class of small-scale structuring exhibiting self-organized criticality that highlights a multi-scaled self-similarity between large-scale, high-temperature coronal fields and the small-scale, lower-temperature QS network. Finally, our QS BP sigmoid elevates arguments for coronal heating contributions from cooler atmospheric layers, as this class of structure may provide evidence favoring mass, energy, and helicity injections into the heliosphere.

  5. Considerations for modeling thin cirrus effects via brightness temperature differences

    Science.gov (United States)

    Schmidt, E. O.; Arduini, R. F.; Wielicki, B. A.; Stone, R. S.; Tsay, S.-C.

    1995-01-01

    Brightness temperature difference (BTD) values are calculated for selected Geostationary Operational Environmental Satellite (GOES-6) channels (3.9, 12.7 micrometer) and Advanced Very High Resolution Radiometer channels (3.7, 12.0 micrometer). Daytime and nighttime discrimination of particle size information is possible given the infrared cloud extinction optical depth and the BTD value. BTD values are presented and compared for cirrus clouds composed of equivalent ice spheres (volume, surface area) versus randomly oriented hexagonal ice crystals. The effect of the hexagonal ice crystals is to increase the magnitude of the BTD values calculated relative to equivalent ice sphere (volume, surface area) BTDs. Equivalent spheres (volume or surface area) do not do a very good job of modeling hexagonal ice crystal effects on BTDs; however, the use of composite spheres improves the simulation and offers interesting prospects. Careful consideration of the number of Legendre polynomial coefficients used to fit the scattering phase functions is crucial to realistic modeling of cirrus BTDs. Surface and view-angle effects are incorporated to provide more realistic simulation.

  6. Magnitude-range brightness variations of overactive K giants

    CERN Document Server

    Oláh, K; Kővári, Zs; Granzer, T; Strassmeier, K G; Kriskovics, L; Vida, K

    2014-01-01

    We study three representative, overactive spotted K giants (IL Hya, XX Tri, and DM UMa) known to exhibit V-band light variations between 0.65-1.05 mags. Our aim is to find the origin of their large brightness variation. We employ long-term phase-resolved multicolor photometry, mostly from automatic telescopes, covering 42 yr for IL Hya, 28 yr for XX Tri, and 34 yr for DM UMa. For one target, IL Hya, we present a new Doppler image from NSO data taken in late 1996. Effective temperatures for our targets are determined from all well-sampled observing epochs and are based on a V-I_C color-index calibration. The effective temperature change between the extrema of the rotational modulation for IL Hya and XX Tri is in the range 50-200 K. The bolometric flux during maximum of the rotational modulation, i.e., the least spotted states, varied by up to 39% in IL Hya and up to 54% in XX Tri over the course of our observations. We emphasize that for IL Hya this is just about half of the total luminosity variation that can...

  7. GMRT HI study of giant low surface brightness galaxies

    Science.gov (United States)

    Mishra, Alka; Kantharia, N. G.; Das, M.; Omar, A.; Srivastava, D. C.

    2016-10-01

    We present HI observations of four giant low surface brightness (GLSB) galaxies UGC 1378, UGC 1922, UGC 4422 and UM 163 using the Giant Meterwave Radio Telescope (GMRT). We include HI results on UGC 2936, UGC 6614 and Malin 2 from literature. HI is detected from all the galaxies and the extent is roughly twice the optical size; in UM 163, HI is detected along a broken disk encircling the optical galaxy. We combine our results with those in literature to further understand these systems. The main results are the following: (1) The peak HI surface densities in GLSB galaxies are several times 1021 cm-2. The HI mass is between 0.3 - 4 × 1010 M⊙, dynamical mass ranges from a few times 1011 M⊙ to a few times 1012 M⊙. (2) The rotation curves of GLSB galaxies are flat to the outermost measured point with rotation velocities of the seven GLSB galaxies being between 225 and 432 km s-1. (3) Recent star formation traced by near-ultraviolet emission in five GLSB galaxies in our sample appears to be located in rings around the galaxy centre. We suggest that this could be due to a stochastic burst of star formation at one location in the galaxy being propagated along a ring over a rotation period. (4) The HI is correlated with recent star formation in five of the seven GLSB galaxies.

  8. The new world atlas of artificial night sky brightness

    CERN Document Server

    Falchi, Fabio; Duriscoe, Dan; Kyba, Christopher C M; Elvidge, Christopher D; Baugh, Kimberly; Portnov, Boris A; Rybnikova, Nataliya A; Furgoni, Riccardo

    2016-01-01

    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{\\deg}N and 60{\\deg}S, 88% of Europe, and almost half of the United States experience light-polluted nights.

  9. The dearth of nuclear star clusters in bright galaxies

    CERN Document Server

    Arca-Sedda, Manuel; Spera, Mario

    2015-01-01

    We investigate the interaction of a massive globular cluster (GC) with a super massive black hole (SMBH), located at the centre of its host galaxy, by means of direct $N$-body simulations. The results show that tidal distortions induced by the stellar background and the SMBH act on a time shorter than that of dynamical friction decay for a $10^6$ M$_\\odot$ GC whenever the SMBH mass exceeds $\\sim 10^8$ M$_\\odot$. This implies an almost complete dissolution of the infalling GC before it reaches the inner region ($\\lesssim 5$ pc) of the parent galaxy. The generalization of this result to a larger sample of infalling GCs shows that such destructive process may prevent the formation and growth of a bright galactic nucleus. Another interesting, serendipitous, result we obtained is that the close interaction between the SMBH and the GC produces a ``wave'' of stars that escape from the cluster and, in a fraction, even from the whole galaxy.

  10. Bright Transients from Black Hole - Neutron Star Mergers

    CERN Document Server

    D'Orazio, Daniel J; Murray, Norman W; Price, Larry

    2016-01-01

    Direct detection of black hole-neutron star (BHNS) pairs is anticipated with the advent of aLIGO. Electromagnetic counterparts may be crucial for a confident gravitational-wave detection as well as for extraction of astronomical information. Yet BHNS star pairs are notoriously dark and so inaccessible to telescopes. Contrary to this expectation, a bright electromagnetic transient can occur in the final moments before merger as long as the neutron star is highly magnetized. The orbital motion of the neutron star magnet creates a Faraday flux and corresponding power available for luminosity. A spectrum of curvature radiation ramps up until the rapid injection of energy ignites a fireball, which would appear as an energetic blackbody peaking in the X-ray to gamma-rays for neutron star field strengths ranging from $10^{12}$G to $10^{16}$G respectively and a $10M_{\\odot}$ black hole. The fireball event may last from a few milliseconds to a few seconds depending on the NS magnetic field strength, and may be observa...

  11. Kinematics of magnetic bright features in the solar photosphere

    CERN Document Server

    Jafarzadeh, Shahin; Cameron, R H; Barthol, P; Rodriguez, J Blanco; Iniesta, J C del Toro; Gandorfer, A; Gizon, L; Hirzberger, J; Knoelker, M; Pillet, V Martinez; Suarez, D Orozco; Riethmueller, T L; Schmidt, W; van Noort, M

    2016-01-01

    Convective flows are known as the prime means of transporting magnetic fields on the solar surface. Thus, small magnetic structures are good tracers of the turbulent flows. We study the migration and dispersal of magnetic bright features (MBFs) in intergranular areas observed at high-spatial resolution with Sunrise/IMaX. We describe the flux dispersal of individual MBFs as a diffusion process whose parameters are computed for various areas in the quiet Sun and the vicinity of active regions from seeing-free data. We find that magnetic concentrations are best described as random walkers close to network areas (diffusion index, gamma=1.0), travelers with constant speeds over a supergranule (gamma=1.9-2.0), and decelerating movers in the vicinity of flux-emergence and/or within active regions (gamma=1.4-1.5). The three types of regions host MBFs with mean diffusion coefficients of 130 km^2/s, 80-90 km^2/s, and 25-70 km^2/s, respectively. The MBFs in these three types of regions are found to display a distinct ki...

  12. 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.; Cognard, I.; Lyne, A. G.; Stappers, B. W.; Freire, P. C. C.; Grove, J. E.; Abdo, A. A.; Desvignes, G.; Donato, D.; Ferrara, E. C.; Gehrels, N.; Guillemot, L.; Gwon, C.; Johnston, S.; Harding, A. K.; Thompson, D. J.

    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 (<= 2 kpc) MSPs. These observations, in combination with the Fermi detection of gamma-rays from other known radio MSPs, imply that most, if not all, radio MSPs are efficient gamma-ray producers. The gamma-ray spectra of the 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.

  13. Sparkling EUV bright dots observed with Hi-C

    CERN Document Server

    Regnier, S; Walsh, R W; Winebarger, A R; Cirtain, J; Golub, L; Korreck, K E; Mitchell, N; Platt, S; Weber, M; 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 towards understanding the finest and fundamental scales of heating events in the solar corona. The 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 11 July 2012, which exhibits several interesting features in the EUV line at 193\\AA: 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 25s 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 suggesting a temperature between 0.5 and 1.5 MK. Based on their frequency in the Hi-C time series, we define four different...

  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. Solar velocity field determined tracking coronal bright points

    Science.gov (United States)

    Brajša, R.; Sudar, D.; Skokić, I.; Saar, S. H.; Žic, T.

    Preliminary data from Atmospheric Imaging Assembly (AIA) instrumenton board Solar Dynamics Observatory (SDO) satellite were used to determine solar differential rotation and related phenomena. A segmentation algorithm, which uses multiple AIA channels in search for intensity enhancements in EUV and X-ray parts of the spectrum compared to the background intensity, was applied to obtain positional information of coronal bright points (CBPs). More than 60000 position measurements of more than 10000 identified CBPs from the period 1 - 2 January 2011 were analyzed. Rotational and meridional velocities were determined by tracking identified CBPs and various filters were used to exclude erroneous results. Also, proper motions of CBPs were calculated from rotation velocity residuals and meridional velocities. Proper motions of CBPs were investigated using a random walk model and the diffusion constant was calculated. These results were compared with the previous ones obtained by other instruments and methods (especially with the SOHO-EIT and Hinode data) and a striking agreement of the obtained diffusion constant with results from other studies was found.

  16. The Environment of Sy1, Sy2 & Bright IRAS Galaxies

    CERN Document Server

    Koulouridis, E; Plionis, M; Dultzin, D; Krongold, Y; Goudis, C; Chatzichristou, E

    2008-01-01

    We present a 3-dimensional study of the local (< 100 kpc) environment of Sy1, Sy2 and Bright IRAS Galaxies. For this purpose we use three galaxy samples (Sy1, Sy2, BIRG) located at high galactic latitudes as well as three control sample of non-active galaxies having the same morphological, redshift and diameter size distributions as the corresponding Seyfert or BIRG sample. Using the CfA2 and SSRS galaxy catalogues as well as our own spectroscopic observations, we find that the fraction of BIRGs with a close neighbor is significantly higher than that of their control sample. We also find that Sy2 galaxies demonstrate the same behaviour with BIRG galaxies but not with Sy1s which do not show any excess of companions with respect to their control sample galaxies. An additional analysis of the relation between FIR colors and activity type of the BIRG's shows a significant difference between the colors of strongly-interacting and non-interacting starbursts and a resemblance between the colors of non-interacting...

  17. 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.

  18. Bright morning light advances the human circadian system without affecting NREM sleep homeostasis

    NARCIS (Netherlands)

    Dijk, Derk Jan; Beersma, Domien G.M.; Daan, Serge; Lewy, Alfred J.

    1989-01-01

    Eight male subjects were exposed to either bright light or dim light between 0600 and 0900 h for 3 consecutive days each. Relative to the dim light condition, the bright light treatment advanced the evening rise in plasma melatonin and the time of sleep termination (sleep onset was held constant) fo

  19. High-current-density, high brightness cathodes for free electron laser applications

    Energy Technology Data Exchange (ETDEWEB)

    Green, M.C. (Varian Associates, Palo Alto, CA (USA). Palo Alto Microwave Tube Div.)

    1987-06-01

    This report discusses the following topics: brightness and emittance of electron beams and cathodes; general requirements for cathodes in high brightness electron guns; candidate cathode types; plasma and field emission cathodes; true field emission cathodes; oxide cathodes; lanthanum hexaborides cathodes; laser driven thermionic cathodes; laser driven photocathodes; impregnated porous tungsten dispenser cathodes; and choice of best performing cathode types.

  20. Low surface brightness galaxies in the local universe .1. The catalog

    NARCIS (Netherlands)

    Impey, CD; Sprayberry, D; Irwin, MJ; Bothun, GD

    1996-01-01

    Data are presented for 693 galaxies identified in a large new survey for low surface brightness galaxies in the nearby universe (z less than or similar to 0.1). The survey covers 786 square degrees centered on the equator, and it extends significantly the surface brightness range of galaxy surveys i

  1. Short Pulse High Brightness X-ray Production with the PLEIADES Thomson Scattering Source

    Energy Technology Data Exchange (ETDEWEB)

    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

    2003-07-01

    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{sup 20} photons/s/0.1% bandwidth/mm{sup 2}/mrad{sup 2}. Initial results are reported and compared to theoretical calculations.

  2. Testing the dark matter hypothesis with low surface brightness galaxies and other evidence

    NARCIS (Netherlands)

    McGaugh, SS; de Blok, WJG

    1998-01-01

    The severity of the mass discrepancy in spiral galaxies is strongly correlated with the central surface brightness of their disks. Progressively lower surface brightness galaxies have ever larger mass discrepancies. No other parameter (luminosity, size, velocity, morphology) is so well correlated wi

  3. The dark and visible matter content of low surface brightness disk galaxies

    NARCIS (Netherlands)

    Blok, W. J. G. de; McGaugh, S. S.

    1997-01-01

    Abstract: We present mass models of a sample of 19 low surface brightness (LSB) galaxies and compare the properties of their constituent mass components with those of a sample of high surface brightness (HSB) galaxies.We find that LSB galaxies are dark matter dominated. Their halo parameters are onl

  4. HI observations of low surface brightness galaxies : Probing low-density galaxies

    NARCIS (Netherlands)

    deBlok, WJG; McGaugh, SS; vanderHulst, JM

    1996-01-01

    We present Very Large Array (VLA) and Westerbork Synthesis Radio Telescope (WSRT) 21-cm HI observations of 19 late-type low surface brightness (LSB) galaxies. Our main findings are that these galaxies, as well as having low surface brightnesses, have low HI surface densities, about a factor of simil

  5. The dark and visible matter content of low surface brightness disc galaxies

    NARCIS (Netherlands)

    deBlok, WJG; McGaugh, SS

    1997-01-01

    We present mass models of a sample of 19 low surface brightness (LSB) galaxies and compare the properties of their constituent mass components with those of a sample of high surface brightness (HSB) galaxies. We find that LSB galaxies are dark matter dominated, Their halo parameters are only slightl

  6. X-ray Fluorescence Sectioning

    CERN Document Server

    Cong, Wenxiang

    2012-01-01

    In this paper, we propose an x-ray fluorescence imaging system for elemental analysis. The key idea is what we call "x-ray fluorescence sectioning". Specifically, a slit collimator in front of an x-ray tube is used to shape x-rays into a fan-beam to illuminate a planar section of an object. Then, relevant elements such as gold nanoparticles on the fan-beam plane are excited to generate x-ray fluorescence signals. One or more 2D spectral detectors are placed to face the fan-beam plane and directly measure x-ray fluorescence data. Detector elements are so collimated that each element only sees a unique area element on the fan-beam plane and records the x-ray fluorescence signal accordingly. The measured 2D x-ray fluorescence data can be refined in reference to the attenuation characteristics of the object and the divergence of the beam for accurate elemental mapping. This x-ray fluorescence sectioning system promises fast fluorescence tomographic imaging without a complex inverse procedure. The design can be ad...

  7. Assessing Photosynthesis by Fluorescence Imaging

    Science.gov (United States)

    Saura, Pedro; Quiles, Maria Jose

    2011-01-01

    This practical paper describes a novel fluorescence imaging experiment to study the three processes of photochemistry, fluorescence and thermal energy dissipation, which compete during the dissipation of excitation energy in photosynthesis. The technique represents a non-invasive tool for revealing and understanding the spatial heterogeneity in…

  8. 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.

  9. Copper bromide vapor brightness amplifiers with 100 kHz pulse repetition frequency

    Science.gov (United States)

    Trigub, M. V.; Evtushenko, G. S.; Torgaev, S. N.; Shiyanov, D. V.; Evtushenko, T. G.

    2016-10-01

    The paper presents a laser monitor with 10 μs time-resolution based on a high-frequency copper bromide vapor brightness amplifier. A sync circuit has been designed for single-pulse imaging. The analysis of amplifying characteristics of the active elements and active optical system (laser monitor) parameters allowed to determine the optimal concentration of HBr at which the images can be obtained with minimum distortions. For the active element operating at high frequencies (more than 50 kHz) as a brightness amplifier, the concentration of HBr must be lower than that needed for obtaining the maximum output power. The limiting brightness temperature of the background radiation which does not affect the image quality is determined. The potential feasibility of using a proposed brightness amplifier for visualizing processes blocked from viewing by the background radiation with the brightness temperature up to 8000 K is demonstrated.

  10. CHLORINE DIOXIDE BLEACHING OF SODA-ANTHRAQUINONE JUTE PULP TO A VERY HIGH BRIGHTNESS

    Directory of Open Access Journals (Sweden)

    M. Sarwar Jahan

    2010-05-01

    Full Text Available Bleaching of soda-anthraquinone jute pulp by chlorine dioxide (ClO2 was studied to reach a target brightness of above 88% for the purpose of using less bleaching chemicals. The performance of either chlorine dioxide or peroxide in the final bleaching to boost brightness was also studied. The experimental results revealed that the final brightness depended on ClO2 charge in the Do and D1 stages. The brightness reversion was lower when the final stage brightening was done by peroxide. The use of Mg(OH2 in the D1 and D2 stages improved the final brightness due to the formation of less chlorate and chlorite during the Mg(OH2- based ClO2 brightening stages. The strength properties of pulp bleached by peroxide in the final stage was slightly better than that from ClO2 as the final ClO2 bleaching stage.

  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. Halley's true brightness in 1909-11 and comparison to 1985-86

    Science.gov (United States)

    Marcus, Joseph N.

    1986-12-01

    Major disparities in the brightness observations of Halley's comet in 1909 to 1911 are resolved by demonstrating that the major visual observers estimated the brightness of only the central condensation, and not the total coma (m1). The resulting brightness underestimation is further exacerbated when the coma is magnified, either by instrument or by near-Earth distance (delta effect). Nearly all analyses of the 1910 brightness (including the one on which the International Halley Watch based its preperihelion forecast) do not account for these artifacts and lead to the erroneous conclusion that Halley was dimmer in 1910 than in 1986. Analysis of the 1910 data, compensating for the artifact, led to a successful brightness forecast for 1985 to 1986 and to the conclusion that there is no significant difference in the comet's photometric behavior between the apparitions.

  13. Benzothiadiazole Derivatives as Fluorescence Imaging Probes: Beyond Classical Scaffolds.

    Science.gov (United States)

    Neto, Brenno A D; Carvalho, Pedro H P R; Correa, Jose R

    2015-06-16

    as pure solids, no fading even after long periods of irradiation, bright emissions with no blinking, good signal-to-noise ratios, efficiency to transpose the cell membrane, and irradiation preferentially in the visible-light region are just some features noted by using BTDs. As the pioneering group in the use of fluorescent small-molecule BTDs for bioimaging purposes, we feel pleased to share our experience, results, advances, and personal perspectives with the readers of this Account. The readers will clearly note the huge advantages of using fluorescent BTDs over classical scaffolds, and hopefully they will be inspired and motivated to further BTD technology in the fields of molecular and cellular biology.

  14. Simultaneous stable expression of neomycin phosphotransferase and green fluorescence protein genes in Trypanosoma cruzi.

    Science.gov (United States)

    dos Santos, W G; Buck, G A

    2000-12-01

    The ribosomal RNA (rRNA) gene promoter was used to construct plasmid vectors that simultaneously express multiple exogenous genes in Trypanosoma cruzi. Vector pBSPANEO expresses neomycin phosphotransferase, and pPAGFPAN expresses both green fluorescent protein and neomycin phosphotransferase from a single promoter. Both vectors require the presence of the rRNA promoter for stable transfection; epimastigotes transfected with pPAGFPAN strongly fluoresced due to green fluorescent protein expression. Intact plasmids were rescued from the T. cruzi-transfected population after >8 mo of culture, indicating stable replication of these vectors. Vectors were integrated into the rRNA locus by homologous recombination and into other loci, presumably by illegitimate recombination. Parasites bearing tandem concatamers of plasmids were also found among the transfectants. Transfectants expressing green fluorescent protein showed a bright green fluorescence distributed throughout the cell. Fluorescence was also detected in amastigotes after infection of mammalian cells with transfected parasites, indicating that the rRNA promoter can drive efficient expression of these reporter genes in multiple life-cycle stages of the parasite. Expression of the heterologous genes was detected after passage in mice or in the insect vector. These vectors will be useful for the genetic dissection of T. cruzi biology and pathogenesis.

  15. Phthalocyanine dye as an extremely photostable and highly fluorescent near-infrared labeling reagent

    Science.gov (United States)

    Peng, Xinzhan; Draney, Daniel R.; Volcheck, William M.; Bashford, Gregory R.; Lamb, Donald T.; Grone, Daniel L.; Zhang, Yonghong; Johnson, Craig M.

    2006-02-01

    Current organic fluorophores used as labeling reagents for biomolecule conjugation have significant limitations in photostability. This compromises their performance in applications that require a photostable fluorescent reporting group. For example, in molecular imaging and single molecule microscopy, photostable fluorescent labels are important for observing and tracking individual molecular events over extended period of time. We report in this paper an extremely photostable and highly fluorescent phthalocyanine dye, IRDye TM 700DX, as a near-infrared fluorescence labeling reagent to conjugate with biomolecules. This novel water-soluble silicon phthalocyanine dye has an isomericly pure chemical structure. The dye is about 45 to 128 times more photostable than current near-IR fluorophores, e.g. Alexa Fluor"R"680, Cy TM 5.5, Cy TM 7 and IRDye TM 800CW dyes; and about 27 times more photostable than tetramethylrhodamine (TMR), one of the most photostable organic dyes. This dye also meets all the other stringent requirements as an ideal fluorophore for biomolecules labeling such as excellent water solubility, no aggregation in high ionic strength buffer, large extinction coefficient and high fluorescent quantum yield. Antibodies conjugated with IRDye TM 700DX at high D/P ratio exist as monomeric species in high ionic buffer and have bright fluorescence. The IRDye TM 700DX conjugated antibodies generate sensitive, highly specific detection with very low background in Western blot and cytoblot assays.

  16. Endoscopic fluorescence imaging for early assessment of anastomotic recurrence of Crohn's disease

    Science.gov (United States)

    Mordon, Serge R.; Maunoury, Vincent; Geboes, K.; Klein, Olivier; Desreumaux, P.; Debaert, A.; Colombel, Jean-Frederic

    1999-02-01

    Crohn's disease is an inflammatory bowel disease of unknown etiology. The mechanism of the initial mucosal alterations is still unclear: ulcerations overlying lymphoid follicles and/or vasculitis have been proposed as the early lesions. We have developed a new and original method combining endoscopy of fluorescence angiography for identifying the early pathological lesions, occurring in the neo-terminal ileum after right ileocolonic resection. The patient population consisted of 10 subjects enrolled in a prospective protocol of endoscopic follow-up at 3 and 12 months after surgery. Fluorescence imaging showed small spots giving a bright fluorescence distributed singly in mucosa which appeared normal in routine endoscopy. Histopathological examination demonstrated that the fluorescence of small spots originated from small, usually superficial, erosive lesions. In several cases, these erosive lesions occurred over lymphoid follicles. Endoscopic fluorescence imaging provides a suitable means of investigating the initial aspect of the Crohn's disease process in displaying some correlative findings between fluorescent aspects and early pathological mucosal alterations.

  17. Green Synthesis of Fluorescent Carbon Dots for Selective Detection of Tartrazine in Food Samples.

    Science.gov (United States)

    Xu, Hua; Yang, Xiupei; Li, Gu; Zhao, Chuan; Liao, Xiangjun

    2015-08-05

    A simple, economical, and green method for the preparation of water-soluble, high-fluorescent carbon quantum dots (C-dots) has been developed via hydrothermal process using aloe as a carbon source. The synthesized C-dots were characterized by atomic force microscope (AFM), transmission electron microscopy (TEM), fluorescence spectrophotometer, UV-vis absorption spectra as well as Fourier transform infrared spectroscopy (FTIR). The results reveal that the as-prepared C-dots were spherical shape with an average diameter of 5 nm and emit bright yellow photoluminescence (PL) with a quantum yield of approximately 10.37%. The surface of the C-dots was rich in hydroxyl groups and presented various merits including high fluorescent quantum yield, excellent photostability, low toxicity and satisfactory solubility. Additionally, we found that one of the widely used synthetic food colorants, tartrazine, could result in a strong fluorescence quenching of the C-dots through a static quenching process. The decrease of fluorescence intensity made it possible to determine tartrazine in the linear range extending from 0.25 to 32.50 μM, This observation was further successfully applied for the determination of tartrazine in food samples collected from local markets, suggesting its great potential toward food routine analysis. Results from our study may shed light on the production of fluorescent and biocompatible nanocarbons due to our simple and environmental benign strategy to synthesize C-dots in which aloe was used as a carbon source.

  18. A new self-made digital slide scanner and microscope for imaging and quantification of fluorescent microspheres

    DEFF Research Database (Denmark)

    Henning, William; Bjerglund Andersen, Julie; Højgaard, Liselotte

    2015-01-01

    Objective: A low-cost microscope slide scanner was constructed for the purpose of digital imaging of newborn piglet brain tissue and to quantify fluorescent microspheres in tissue. Methods: Using a standard digital single-lens reflex (DSLR) camera, fluorescent imaging of newborn piglet brain tissue...... was performed. A computer algorithm available for download was created to detect fluorescent microspheres in the brain tissue slides and to calculate regional cerebral blood flow (rCBF). The precision of the algorithm was tested by comparing with manual counting of the fluorescent microspheres. Finally, bright...... with a resolution of 2.9 µm. The mean difference (SD) between manual and automatic counts was in absolute numbers 0.32 (1.5) microspheres ranging from -5 to 5 microspheres per slide. The relative total difference between automatic and manual counts was -3.1%. Conclusions: A slide scanner was constructed...

  19. Optical Properties of Fluorescent Dyes

    Institute of Scientific and Technical Information of China (English)

    李戎; 陈东辉

    2001-01-01

    Fluorescent dyes have been widely used these years.Because of the special optical performance, conventional CCM systems seem to be unable to predict the recipes of fabrics dyed with fluorescent dyes. In order to enhance the functions of CCM systems, the optical properties of fluorescent dyes in their absorption region were investigated. It has been found that there was a fixed maximum absorption wavelength for each fluorescent dyes whatever its concentration is. Both absorption region and maximum absorption wavelength of the dyes in solution are the same to those in fabric, and that the absorption is directly proportional to the concentration of the dye. So the optical properties obtained in solutions cna be applied for describing the optics performance of fluorescent dyes in fabrics.

  20. A new perspective on the infrared brightness temperature distribution of the deep convective clouds

    Indian Academy of Sciences (India)

    Rakesh Teja Konduru; C M Kishtawal; Shivani Shah

    2013-10-01

    We are proposing a statistical technique to analyze the best fit of the histogram of infrared brightness temperature of convective cloud pixels. For this we have utilized the infrared brightness temperatures (IRTB) of Kalpana-1 (8 km resolution) and globally merged infrared brightness temperatures of Climate Prediction Centre NCEP/NWS (4 km resolution, merged from all the available geostationary satellites GOES-8/10, METEOSAT-7/5 and GMS), for both deep convective and non-deep convective (shallow cloud) cases. It is observed that Johnson SB function is the best continuous distribution function in explaining the histogram of infrared brightness temperatures of the convective clouds. The best fit is confirmed by Kolmogorov–Smirnov statistic. Johnson SB’s distribution of histogram of infrared brightness temperatures clearly discriminates the cloud pixels of deep convective and non-deep convective cases. It also captures the asymmetric nature in histogram of infrared brightness temperatures. We also observed that Johnson SB distribution of infrared brightness temperatures for deep convective systems is different in each of the pre-monsoon, monsoon and post-monsoon seasons. And Johnson SB parameters are observed to be best in discriminating the Johnson SB distribution of infrared brightness temperatures of deep convective systems for each season. Due to these properties of Johnson SB function, it can be utilized in the modelling of the histogram of infrared brightness temperature of deep convective and non-deep convective systems. It focuses a new perspective on the infrared brightness temperature that will be helpful in cloud detection, classification and modelling.

  1. Fluorescent cyanine probe for DNA detection and cellular imaging

    Science.gov (United States)

    Zheng, Yong-Chao; Zheng, Mei-Ling; Zhao, Zhen-Sheng; Duan, Xuan-Ming

    2014-03-01

    In our study, two carbazole-based cyanines, 3,6-bis[2-(1-methylpyridinium)vinyl]-9-methyl carbazole diiodide (A) and 6,6'-bis[2-(1-methylpyridinium)vinyl]-bis(9-methyl-carbazol-3yl)methane diiodide (B) were synthesized and employed as light-up probes for DNA and cell imaging. Both of the cyanine probes possess a symmetric structure and bis-cationic center. The obvious induced circular dichroism signals in circular dichroism spectra reveal that the molecules can specifically interact with DNA. Strong fluorescence enhancement is observed when these two cyanines are bound to DNA. These cyanine probes show high binding affinity to oligonucleotides but different binding preferences to various secondary structures. Confocal microscopy images of fixed cell stained by the probes exhibit strong brightness and high contrast in nucleus with a very low cytoplasmic background.

  2. The electronic excited states of green fluorescent protein chromophore models

    Science.gov (United States)

    Olsen, Seth Carlton

    We explore the properties of quantum chemical approximations to the excited states of model chromophores of the green fluorescent protein of A. victoria. We calculate several low-lying states by several methods of quantum chemical calculation, including state-averaged complete active space SCF (CASSCF) methods, time dependent density functional theory (TDDFT), equation-of motion coupled cluster (EOM-CCSD) and multireference perturbation theory (MRPT). Amongst the low-lying states we identify the optically bright pipi* state of the molecules and examine its properties. We demonstrate that the state is dominated by a single configuration function. We calculate zero-time approximations to the resonance Raman spectrum of GFP chromophore models, and assign published spectra based upon these.

  3. Fluorescence Quenching of Benzaldehyde in Water by Hydrogen Atom Abstraction.

    Science.gov (United States)

    Fletcher, Katharyn; Bunz, Uwe H F; Dreuw, Andreas

    2016-09-01

    We computed the mechanism of fluorescence quenching of benzaldehyde in water through relaxed potential energy surface scans. Time-dependent density functional theory calculations along the protonation coordinate from water to benzaldehyde reveal that photoexcitation to the bright ππ* (S3 ) state is immediately followed by ultrafast decay to the nπ* (S1 ) state. Evolving along this state, benzaldehyde (BA) abstracts a hydrogen atom, resulting in a BAH(.) and OH(.) radical pair. Benzaldehyde does not act as photobase in water, but abstracts a hydrogen atom from a nearby solvent molecule. The system finally decays back to the ground state by non-radiative decay and an electron transfers back to the OH(.) radical. Proton transfer from BAH(+) to OH(-) restores the initial situation, BA in water.

  4. Adapting High Brightness Relativistic Electron Beams for Ultrafast Science

    Science.gov (United States)

    Scoby, Cheyne Matthew

    This thesis explores the use of ultrashort bunches generated by a radiofrequency electron photoinjector driven by a femtosecond laser. Rf photoinjector technology has been developed to generate ultra high brightness beams for advanced accelerators and to drive advanced light source applications. The extremely good quality of the beams generated by this source has played a key role in the development of 4th generation light sources such as the Linac Coherent Light Source, thus opening the way to studies of materials science and biological systems with high temporal and spatial resolution. At the Pegasus Photoinjector Lab, we have developed the application of a BNL/SLAC/UCLA 1.6-cell rf photoinjector as a tool for ultrafast science in its own right. It is the aim of this work to explore the generation of ultrashort electron bunches, give descriptions of the novel ultrafast diagnostics developed to be able to characterize the electron bunch and synchronize it with a pump laser, and share some of the scientific results that were obtained with this technology at the UCLA Pegasus laboratory. This dissertation explains the requirements of the drive laser source and describes the principles of rf photoinjector design and operation necessary to produce electron bunches with an rms longitudinal length < 100 femtoseconds containing 107 - 108 electrons per bunch. In this condition, when the laser intensity is sufficiently high, multiphoton photoemission is demonstrated to be more efficient in terms of charge yield than single photon photoemission. When a short laser pulse hits the cathode the resulting beam dynamics are dominated by a strong space charge driven longitudinal expansion which leads to the creation of a nearly ideal uniformly filled ellipsoidal distribution. These beam distributions are characterized by linear space charge forces and hence by high peak brightness and small transverse emittances. This regime of operation of the RF photoinjector is also termed the

  5. Voltage-sensitive rhodol with enhanced two-photon brightness.

    Science.gov (United States)

    Kulkarni, Rishikesh U; Kramer, Daniel J; Pourmandi, Narges; Karbasi, Kaveh; Bateup, Helen S; Miller, Evan W

    2017-03-14

    We have designed, synthesized, and applied a rhodol-based chromophore to a molecular wire-based platform for voltage sensing to achieve fast, sensitive, and bright voltage sensing using two-photon (2P) illumination. Rhodol VoltageFluor-5 (RVF5) is a voltage-sensitive dye with improved 2P cross-section for use in thick tissue or brain samples. RVF5 features a dichlororhodol core with pyrrolidyl substitution at the nitrogen center. In mammalian cells under one-photon (1P) illumination, RVF5 demonstrates high voltage sensitivity (28% ΔF/F per 100 mV) and improved photostability relative to first-generation voltage sensors. This photostability enables multisite optical recordings from neurons lacking tuberous sclerosis complex 1, Tsc1, in a mouse model of genetic epilepsy. Using RVF5, we show that Tsc1 KO neurons exhibit increased activity relative to wild-type neurons and additionally show that the proportion of active neurons in the network increases with the loss of Tsc1. The high photostability and voltage sensitivity of RVF5 is recapitulated under 2P illumination. Finally, the ability to chemically tune the 2P absorption profile through the use of rhodol scaffolds affords the unique opportunity to image neuronal voltage changes in acutely prepared mouse brain slices using 2P illumination. Stimulation of the mouse hippocampus evoked spiking activity that was readily discerned with bath-applied RVF5, demonstrating the utility of RVF5 and molecular wire-based voltage sensors with 2P-optimized fluorophores for imaging voltage in intact brain tissue.

  6. VELOCITY BUNCHING OF HIGH-BRIGHTNESS ELECTRON BEAMS

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S G; Musumeci, P; Rosenzweig, J B; Brown, W J; England, R J; Ferrario, M; Jacob, J S; Thompson, M C; Travish, G; Tremaine, A M; Yoder, R

    2004-10-15

    Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS) experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly in ICS experiments

  7. Bright light-emitting diodes based on organometal halide perovskite.

    Science.gov (United States)

    Tan, Zhi-Kuang; Moghaddam, Reza Saberi; Lai, May Ling; Docampo, Pablo; Higler, Ruben; Deschler, Felix; Price, Michael; Sadhanala, Aditya; Pazos, Luis M; Credgington, Dan; Hanusch, Fabian; Bein, Thomas; Snaith, Henry J; Friend, Richard H

    2014-09-01

    Solid-state light-emitting devices based on direct-bandgap semiconductors have, over the past two decades, been utilized as energy-efficient sources of lighting. However, fabrication of these devices typically relies on expensive high-temperature and high-vacuum processes, rendering them uneconomical for use in large-area displays. Here, we report high-brightness light-emitting diodes based on solution-processed organometal halide perovskites. We demonstrate electroluminescence in the near-infrared, green and red by tuning the halide compositions in the perovskite. In our infrared device, a thin 15 nm layer of CH3NH3PbI(3-x)Cl(x) perovskite emitter is sandwiched between larger-bandgap titanium dioxide (TiO2) and poly(9,9'-dioctylfluorene) (F8) layers, effectively confining electrons and holes in the perovskite layer for radiative recombination. We report an infrared radiance of 13.2 W sr(-1) m(-2) at a current density of 363 mA cm(-2), with highest external and internal quantum efficiencies of 0.76% and 3.4%, respectively. In our green light-emitting device with an ITO/PEDOT:PSS/CH3NH3PbBr3/F8/Ca/Ag structure, we achieved a luminance of 364 cd m(-2) at a current density of 123 mA cm(-2), giving external and internal quantum efficiencies of 0.1% and 0.4%, respectively. We show, using photoluminescence studies, that radiative bimolecular recombination is dominant at higher excitation densities. Hence, the quantum efficiencies of the perovskite light-emitting diodes increase at higher current densities. This demonstration of effective perovskite electroluminescence offers scope for developing this unique class of materials into efficient and colour-tunable light emitters for low-cost display, lighting and optical communication applications.

  8. Search for bright nearby M dwarfs with virtual observatory tools

    Energy Technology Data Exchange (ETDEWEB)

    Aberasturi, M.; Caballero, J. A.; Montesinos, B.; Gálvez-Ortiz, M. C.; Solano, E.; Martín, E. L. [Centro de Astrobiología (CSIC-INTA), Departamento de Astrofísica, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid (Spain)

    2014-08-01

    Using Virtual Observatory tools, we cross-matched the Carlsberg Meridian 14 and the 2MASS Point Source catalogs to select candidate nearby bright M dwarfs distributed over ∼25,000 deg{sup 2}. Here, we present reconnaissance low-resolution optical spectra for 27 candidates that were observed with the Intermediate Dispersion Spectrograph at the 2.5 m Isaac Newton Telescope (R≈ 1600). We derived spectral types from a new spectral index, R, which measures the ratio of fluxes at 7485-7015 Å and 7120-7150 Å. We also used VOSA, a Virtual Observatory tool for spectral energy distribution fitting, to derive effective temperatures and surface gravities for each candidate. The resulting 27 targets were M dwarfs brighter than J = 10.5 mag, 16 of which were completely new in the Northern hemisphere and 7 of which were located at less than 15 pc. For all of them, we also measured Hα and Na I pseudo-equivalent widths, determined photometric distances, and identified the most active stars. The targets with the weakest sodium absorption, namely, J0422+2439 (with X-ray and strong Hα emissions), J0435+2523, and J0439+2333, are new members in the young Taurus-Auriga star-forming region based on proper motion, spatial distribution, and location in the color-magnitude diagram, which reopens the discussion on the deficit of M2-4 Taurus stars. Finally, based on proper motion diagrams, we report on a new wide M dwarf binary system in the field, LSPM J0326+3929EW.

  9. Spatial and Spectral Brightness Enhancement of High Power Semiconductor Lasers

    Science.gov (United States)

    Leidner, Jordan Palmer

    The performance of high-power broad-area diode lasers is inhibited by beam filamentation induced by free-carrier-based self-focusing. The resulting beam degradation limits their usage in high-brightness, high-power applications such as pumping fiber lasers, and laser cutting, welding, or marking. Finite-difference propagation method simulations via RSoft's BeamPROP commercial simulation suite and a custom-built MATLAB code were used for the study and design of laser cavities that suppress or avoid filamentation. BeamPROP was used to design a tapered, passive, multi-mode interference cavity for the creation of a self-phase-locking laser array, which is comprised of many single-mode gain elements coupled to a wide output coupler to avoid damage from local high optical intensities. MATLAB simulations were used to study the effects of longitudinal and lateral cavity confinement on lateral beam quality in conventional broad-area lasers. This simulation was expanded to design a laser with lateral gain and index prescription that is predicted to operate at or above state-of-the-art powers while being efficiently coupled to conventional telecom single-mode optical fibers. Experimentally, a commercial broad-area laser was coupled in the far-field to a single-mode fiber Bragg grating to provide grating-stabilized single-mode laser feedback resulting in measured spectral narrowing for efficient pump absorption. Additionally a 19 GHz-span, spatially resolved, self-heterodyne measurement was made of a broad-area laser to study the evolution/devolution of the mode content of the emitted laser beam with increasing power levels.

  10. An ultraviolet imager to study bright UV sources

    Science.gov (United States)

    Mathew, Joice; Prakash, Ajin; Sarpotdar, Mayuresh; Sreejith, A. G.; Safonova, Margarita; Murthy, Jayant

    2016-07-01

    We have designed and developed a compact ultraviolet imaging payload to y on a range of possible platforms such as high altitude balloon experiments, cubesats, space missions, etc. The primary science goals are to study the bright UV sources (mag < 10) and also to look for transients in the Near UV (200 - 300 nm) domain. Our first choice is to place this instrument on a spacecraft going to the Moon as part of the Indian entry into Google lunar X-Prize competition. The major constraints for the instrument are, it should be lightweight (< 2Kg), compact (length < 50cm) and cost effective. The instrument is an 80 mm diameter Cassegrain telescope with a field of view of around half a degree designated for UV imaging. In this paper we will discuss about the various science cases that can be performed by having observations with the instrument on different platforms. We will also describe the design, development and the current state of implementation of the instrument. This includes opto-mechanical and electrical design of the instrument. We have adopted an all spherical optical design which would make the system less complex to realize and a cost effective solution compared to other telescope configuration. The structural design has been chosen in such a way that it will ensure that the instrument could withstand all the launch load vibrations. An FPGA based electronics board is used for the data acquisition, processing and CCD control. We will also brie y discuss about the hardware implementation of the detector interface and algorithms for the detector readout and data processing.

  11. Ratiometric fluorescence transduction by hybridization after isothermal amplification for determination of zeptomole quantities of oligonucleotide biomarkers with a paper-based platform and camera-based detection

    Energy Technology Data Exchange (ETDEWEB)

    Noor, M. Omair; Hrovat, David [Chemical Sensors Group, Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON L5L 1C6 (Canada); Moazami-Goudarzi, Maryam [Department of Cell and Systems Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON L5L 1C6 (Canada); Espie, George S. [Department of Cell and Systems Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON L5L 1C6 (Canada); Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON L5L 1C6 (Canada); Krull, Ulrich J., E-mail: ulrich.krull@utoronto.ca [Chemical Sensors Group, Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, ON L5L 1C6 (Canada)

    2015-07-23

    Highlights: • Solid-phase QD-FRET transduction of isothermal tHDA amplicons on paper substrates. • Ratiometric QD-FRET transduction improves assay precision and lowers the detection limit. • Zeptomole detection limit by an iPad camera after isothermal amplification. • Tunable assay sensitivity by immobilizing different amounts of QD–probe bioconjugates. - Abstract: Paper is a promising platform for the development of decentralized diagnostic assays owing to the low cost and ease of use of paper-based analytical devices (PADs). It can be challenging to detect on PADs very low concentrations of nucleic acid biomarkers of lengths as used in clinical assays. Herein we report the use of thermophilic helicase-dependent amplification (tHDA) in combination with a paper-based platform for fluorescence detection of probe-target hybridization. Paper substrates were patterned using wax printing. The cellulosic fibers were chemically derivatized with imidazole groups for the assembly of the transduction interface that consisted of immobilized quantum dot (QD)–probe oligonucleotide conjugates. Green-emitting QDs (gQDs) served as donors with Cy3 as the acceptor dye in a fluorescence resonance energy transfer (FRET)-based transduction method. After probe-target hybridization, a further hybridization event with a reporter sequence brought the Cy3 acceptor dye in close proximity to the surface of immobilized gQDs, triggering a FRET sensitized emission that served as an analytical signal. Ratiometric detection was evaluated using both an epifluorescence microscope and a low-cost iPad camera as detectors. Addition of the tHDA method for target amplification to produce sequences of ∼100 base length allowed for the detection of zmol quantities of nucleic acid targets using the two detection platforms. The ratiometric QD-FRET transduction method not only offered improved assay precision, but also lowered the limit of detection of the assay when compared with the non

  12. Fluorescence endoscopy and photodynamic therapy.

    Science.gov (United States)

    Messmann, H; Endlicher, E; Gelbmann, C M; Schölmerich, J

    2002-10-01

    Fluorescence endoscopy is a new technique which allows a better detection of non-visible malignant or premalignant lesions or, those which are difficult to detect. Exogenously applied sensitisers accumulate selectively in malignant lesions and induce fluorescence after illumination with light of adequate wavelength. However, also endogenous fluorophores, different located in malignant or benign lesions, induce a different autofluorescence in these lesions. Tissue fluorescence can be detected by optical sampling of the mucosa using fluorescence spectroscopy or by generating real time fluorescence images with specialised camera systems. Compared to point fluorescence spectroscopy the latter technique enables the screening of large surface areas of mucosa. Meanwhile, fluorescence endoscopy is a widely used technique in urology employing 5-aminolaevulinic acid sensitisation. In gastroenterology, this technique seems promising for the detection of early cancers or dysplasia in patients with Barrett's oesophagus or ulcerative colitis. Using different sensitisers, photodynamic therapy seems to be a promising option for patients with advanced oesophageal cancer and in the palliative treatment of non-resectable bile duct cancer, furthermore for patients with early gastric cancer and dysplasia in Barrett's oesophagus. Probably, by laser light fractionation or a combination of different sensitisers, an enhanced effect can be expected.

  13. FLEX: fluorescence explorer

    Science.gov (United States)

    Stoll, Marc-Ph.; Court, Andrew; Smorenburg, Kees; Visser, Huib; Crocco, Luiggi; Heilimo, Jyro; Honig, Andre

    1999-12-01

    FLEX is a scientifically driven space mission to provide demonstration/validation of the instrumentation and technique for measuring the natural fluorescence of vegetation in the Fraunhofer lines. The payload consists of high spectral resolution (0.1 - 0.3 nm) CCD imaging grating spectrometer with two channels: one in the red (648 - 664 nm) and one in the blue (391 - 438 nm) for working with several Fraunhofer lines. The across track FOV is 8.4 degrees; ground spatial resolution is better than 0.5 X 0.5 km2. To increase the S/N ratio a steering mirror will be used, if necessary, to 'freeze' the image and also to provide plus or minus 4 degrees across track depointing. Calibration is made by viewing the sun via a diffuser plate switched into the telescope field of view. A separate CCD camera will allow cloud detection and scene identification. A TIR radiometer will provide simultaneous surface temperature measurements. The spacecraft, overall mass estimated at 200 kg, is derived from the ASI-MITA bus which provides all the necessary subsystems and stabilized platform. By use of on-board storage, ground requirements for satellite control and data link are minimized; the possibility of local stations for real time reception/distribution is also envisaged. Provisional orbit characteristics are: LEO sun synchronous, 500 - 900 km altitude. Priority will be given to highest revisit frequency on a sufficient number of selected test sites.

  14. Music for a Brighter World: Brightness Judgment Bias by Musical Emotion.

    Science.gov (United States)

    Bhattacharya, Joydeep; Lindsen, Job P

    2016-01-01

    A prevalent conceptual metaphor is the association of the concepts of good and evil with brightness and darkness, respectively. Music cognition, like metaphor, is possibly embodied, yet no study has addressed the question whether musical emotion can modulate brightness judgment in a metaphor consistent fashion. In three separate experiments, participants judged the brightness of a grey square that was presented after a short excerpt of emotional music. The results of Experiment 1 showed that short musical excerpts are effective emotional primes that cross-modally influence brightness judgment of visual stimuli. Grey squares were consistently judged as brighter after listening to music with a positive valence, as compared to music with a negative valence. The results of Experiment 2 revealed that the bias in brightness judgment does not require an active evaluation of the emotional content of the music. By applying a different experimental procedure in Experiment 3, we showed that this brightness judgment bias is indeed a robust effect. Altogether, our findings demonstrate a powerful role of musical emotion in biasing brightness judgment and that this bias is aligned with the metaphor viewpoint.

  15. Music for a Brighter World: Brightness Judgment Bias by Musical Emotion.

    Directory of Open Access Journals (Sweden)

    Joydeep Bhattacharya

    Full Text Available A prevalent conceptual metaphor is the association of the concepts of good and evil with brightness and darkness, respectively. Music cognition, like metaphor, is possibly embodied, yet no study has addressed the question whether musical emotion can modulate brightness judgment in a metaphor consistent fashion. In three separate experiments, participants judged the brightness of a grey square that was presented after a short excerpt of emotional music. The results of Experiment 1 showed that short musical excerpts are effective emotional primes that cross-modally influence brightness judgment of visual stimuli. Grey squares were consistently judged as brighter after listening to music with a positive valence, as compared to music with a negative valence. The results of Experiment 2 revealed that the bias in brightness judgment does not require an active evaluation of the emotional content of the music. By applying a different experimental procedure in Experiment 3, we showed that this brightness judgment bias is indeed a robust effect. Altogether, our findings demonstrate a powerful role of musical emotion in biasing brightness judgment and that this bias is aligned with the metaphor viewpoint.

  16. A one-pot reaction to synthesize two types of fluorescent materials containing benzothiazolyl moiety.

    Science.gov (United States)

    Yu, Tianzhi; Zhang, Chengcheng; Zhao, Yuling; Chai, Haifang; Fan, Duowang; Ma, Ying; Yao, Shanglei; Li, Wentao

    2013-05-01

    Two different types of fluorescent materials containing benzothiazolyl moiety, 2-(benzothiazol-2-yl)phenol derivatives and 3-(benzothiazol-2-yl)coumarin derivatives, were synthesized synchronously using ethyl cyanoacetate, appropriate aromatic aldehyde and 2-aminothiophenol as the starting materials under the catalysis of benzoic acid by one-pot reaction. This method has the advantages of mild reaction conditions, easy processing and low waste. All synthesized compounds were characterized by elemental analysis, IR, (1)H NMR spectra. The structures of 2-(benzothiazol-2-yl)phenol derivatives, 2-(benzothiazol-2-yl)phenol (BTP) and 2-(benzothiazol-2-yl)naphthol (BTN), were determined by X-ray single crystal analysis. The UV-vis absorption and photoluminescence spectra of all synthesized compounds were investigated. The 2-(benzothiazol-2-yl)phenol derivatives exhibit bright green emissions and 3-(benzothiazol-2-yl)coumarin derivatives emit bright blue light in solutions.

  17. Intramolecular fluorescence resonance energy transfer and living cell imaging of novel pyridyltriphenylamine dye

    Science.gov (United States)

    Cao, Duojun; Qian, Ying

    2016-07-01

    A novel pyridyltriphenylamine-rhodamine dye PTRh and a pyridyltriphenylamine derivative PTO were synthesized and characterized by 1H NMR and HRMS-MALDI-TOF. PTRh performed typical fluorescence resonance energy transfer (FRET) signal from pyridyltriphenylamine to rhodamine along with notable color change from green to rose when interacting with Hg2+ in EtOH/H2O. And PTRh as a ratiometric probe for Hg2+ based on FRET could achieve a very low detection limit of 32 nM and energy transfer efficiency of 83.7% in aqueous organic system. On the other hand, spectra properties of PTO in its aggregates, THF/H2O mixed solution and silica nanoparticles (Si-NPs) dispersed in water were investigated. And the results indicated PTO exhibited bright green fluorescence in solid state, and PTO was successfully encapsulated in silica matrix (30-40 nm), emitting bright blue fluorescence with 11.7% quantum yield. Additionally, living cell imaging experiments demonstrated that PTRh could effectively response to intracellular Hg2+ and PTO-doped Si-NPs were well uptaken by MCF-7 breast cancer cells. It could be concluded that the chromophores are promising materials used as biosensors.

  18. Compact stacking of diode lasers for pulsed light sources of high brightness.

    Science.gov (United States)

    Alahautala, Taito; Lassila, Erkki; Hernberg, Rolf

    2004-07-20

    A compact stacking architecture for high-power diode-laser arrays is proposed and compared with traditional stacks. The objective of compact stacking is to achieve high brightness values without the use of microlenses. The calculated brightness for a compact stack is over 300 W mm(-2) sr(-1), which is approximately 40 times higher than that of a traditional stack made of similar laser emitters. Even higher brightness values of over 600 W mm(-2) sr(-1) were reached in practice. A laser head was manufactured in which the light from several compact laser stacks could be fiber coupled or the light could be transformed to a highly uniform beam.

  19. Control and dynamic competition of bright and dark lasing states in active nanoplasmonic metamaterials

    CERN Document Server

    Wuestner, Sebastian; Pusch, Andreas; Renn, Fabian; Tsakmakidis, Kosmas L; Hess, Ortwin

    2011-01-01

    Active nanoplasmonic metamaterials support bright and dark modes that compete for gain. Using a Maxwell-Bloch approach incorporating Langevin noise we study the lasing dynamics in an active nano-fishnet structure. We report that lasing of the bright negative-index mode is possible if the higher-Q dark mode is discriminated by gain, spatially or spectrally. The nonlinear competition during the transient phase is followed by steady-state emission where bright and dark modes can coexist. We analyze the influence of pump intensity and polarization and explore methods for mode control.

  20. Regulation of lipid peroxidation in the retina under the effect of bright light.

    Science.gov (United States)

    Dzhafarov, A I; Kasimov, E M; Mamedov, Sh Y

    2011-04-01

    Changes in LPO intensity under the effect of exposure to bright light and the possibility of their correction with antioxidants were studied on rabbits with diabetic retinopathy. It was found that enhanced LPO caused by exposure to bright light in rabbits with diabetic retinopathy can be corrected with antioxidants. Phenosan potassium salt, α-tocopherol, and oxypyridine were more effective than SOD and taurine in preventing MDA accumulation. A complex of natural and synthetic antioxidants was most efficient in correcting LPO under conditions of exposure to bright light.

  1. On the brightness variations of Comet Halley at large heliocentric distances

    Science.gov (United States)

    Flammer, K. R.; Jackson, B.; Mendis, D. A.

    1986-01-01

    Sporadic variations of its intrinsic brightness of up to 500 percent, with time scales as short as a few hours, has been exhibited by Halley's comet at large heliocentric distances (11-8 AU). It is shown that many of these brightness enhancements are closely correlated to the encounter of high-speed solar wind streams by the comet. It is proposed that during such periods, the night side of the comet gets charged to numerically large negative electrostatic potentials, with consequent electrostatic levitation and blow-off of fine charged dust grains lying on it. This gives rise to the observed brightness variations.

  2. Pioneer 10 observations of zodiacal light brightness near the ecliptic - Changes with heliocentric distance

    Science.gov (United States)

    Hanner, M. S.; Weinberg, J. L.; Beeson, D. E.; Sparrow, J. G.

    1976-01-01

    Sky maps made by the Pioneer 10 Imaging Photopolarimeter (IPP) at sun-spacecraft distances from 1 to 3 AU have been analyzed to derive the brightness of the zodiacal light near the ecliptic at elongations greater than 90 degrees. The change in zodiacal light brightness with heliocentric distance is compared with models of the spatial distribution of the dust. Use of background starlight brightnesses derived from IPP measurements beyond the asteroid belt, where the zodiacal light is not detected, and, especially, use of a corrected calibration lead to considerably lower values for zodiacal light than those reported by us previously.

  3. The Aspect of the Brightness Sensitivity in the Parafovea and Perifovea

    OpenAIRE

    石垣, 尚男

    1984-01-01

    Summary of experiment 1 Using the reaction time method, the brightness sensitivity of 15 retinal loci in the perifovea around the fovea were measured. Stimulus condition : 5′, 16Nit. 100msec, photopic vision Stimulus retinal locus : 6°, 8°, 10° from the fovea, 5 directions on the perifovea in the right eye Subject : 10 right hand dominant subjects Results The nearer to the fovea the retinal locus was, the better the brightness sensitivity in the perifovea was. The brightness sensitivity from ...

  4. Bright-Dark Vector Screening-Photovoltaic Spatial Solitons in Biased Photorefractive-Photovoltaic Crystals

    Institute of Scientific and Technical Information of China (English)

    卢克清; 钱士雄; 窦春升; 吴振森

    2002-01-01

    We show that the vector beam evolution equations in properly oriented biased photorefractive-photovoltaic crystals can exhibit bright-dark vector solitons, which result from both the bulk photovoltaic effect and the spatially non-uniform screening of the external bias field. By adjusting the polarization of the incident beam to obtain the appropriate ratio of two orthogonal components, these vector solitons can be established. When the bulk photovoltaic effect is negligible, these vector solitons are bright-dark vector screening solitons. When the external field is absent, these vector solitons predict bright-dark vector photovoltaic solitons.

  5. Unveiling the nature of bright z ~ 7 galaxies with the Hubble Space Telescope

    CERN Document Server

    Bowler, R A A; McLure, R J; McLeod, D J

    2016-01-01

    We present new Hubble Space Telescope/Wide Field Camera 3 imaging of 25 extremely luminous (-23.2 600A). We find that irregular, multiple-component morphologies suggestive of clumpy or merging systems are common (f_multi > 0.4) in bright z ~ 7 galaxies, and ubiquitous at the very bright end (M_UV 1000 similarly bright galaxies at z ~ 7. Our new HST imaging suggests that the vast majority of these galaxies will be spatially resolved by Euclid, mitigating concerns over dwarf star contamination.

  6. Current State of the Art in High Brightness LEDs

    Science.gov (United States)

    Craford, George

    2007-03-01

    excess of 100 lm/W will become available soon, which is substantially more efficient than incandescents (˜15 lm/W) and compact fluorescents (˜60 lm/W) and equivalent to high performance fluorescent lighting. Performance in the range of 150 lm/W or even higher is plausible in the longer term. This talk will include an overview of the status and trends in LED technology and applications, and the challenges which must be met in order for LED's to become widely utilized in general illumination.

  7. Physical characteristics of bright Class I methanol masers

    Science.gov (United States)

    Leurini, S.; Menten, K. M.; Walmsley, C. M.

    2016-07-01

    Context. Class I methanol masers are thought to be tracers of interstellar shock waves. However, they have received relatively little attention mostly as a consequence of their low luminosities compared to other maser transitions. This situation has changed recently and Class I methanol masers are now routinely used as signposts of outflow activity especially in high extinction regions. The recent detection of polarisation in Class I lines now makes it possible to obtain direct observational information about magnetic fields in interstellar shocks. Aims: We make use of newly calculated collisional rate coefficients for methanol to investigate the excitation of Class I methanol masers and to reconcile the observed Class I methanol maser properties with model results. Methods: We performed large velocity gradient calculations with a plane-parallel slab geometry appropriate for shocks to compute the pump and loss rates which regulate the interactions of the different maser systems with the maser reservoir. We study the dependence of the pump rate coefficient, the maser loss rate, and the inversion efficiency of the pumping scheme of several Class I masers on the physics of the emitting gas. Results: We predict inversion in all transitions where maser emission is observed. Bright Class I methanol masers are mainly high-temperature (>100 K) high-density (n(H2) ~ 107-108 cm-3) structures with methanol maser emission measures, ξ, corresponding to high methanol abundances close to the limits set by collisional quenching. Our model predictions reproduce reasonably well most of the observed properties of Class I methanol masers. Class I masers in the 25 GHz series are the most sensitive to the density of the medium and mase at higher densities than other lines. Moreover, even at high density and high methanol abundances, their luminosity is predicted to be lower than that of the 44 GHz and 36 GHz masers. Our model predictions also reflect the observational result that the

  8. Resonance energy transfer between fluorescent BSA protected Au nanoclusters and organic fluorophores.

    Science.gov (United States)

    Raut, Sangram; Rich, Ryan; Fudala, Rafal; Butler, Susan; Kokate, Rutika; Gryczynski, Zygmunt; Luchowski, Rafal; Gryczynski, Ignacy

    2014-01-01

    Bovine serum albumin (BSA) protected nanoclusters (Au and Ag) represent a group of nanomaterials that holds great promise in biophysical applications due to their unique fluorescence properties and lack of toxicity. These metal nanoclusters have utility in a variety of disciplines including catalysis, biosensing, photonics, imaging and molecular electronics. However, they suffer from several disadvantages such as low fluorescence quantum efficiency (typically near 6%) and broad emission spectrum (540 nm to 800 nm). We describe an approach to enhance the apparent brightness of BSA Au clusters by linking them with a high extinction donor organic dye pacific blue (PB). In this conjugate PB acts as a donor to BSA Au clusters and enhances its brightness by resonance energy transfer (RET). We found that the emission of BSA Au clusters can be enhanced by a magnitude of two-fold by resonance energy transfer (RET) from the high extinction donor PB, and BSA Au clusters can act as an acceptor to nanosecond lifetime organic dyes. By pumping the BSA Au clusters using a high extinction donor, one can increase the effective brightness of less bright fluorophores like BSA Au clusters. Moreover, we prepared another conjugate of BSA Au clusters with the near infrared (NIR) dye Dylight 750 (Dy750), where BSA Au clusters act as a donor to Dy750. We observed that BSA Au clusters can function as a donor, showing 46% transfer efficiency to the NIR dye Dy750 with a long lifetime component in the acceptor decay through RET. Such RET-based probes can be used to prevent the problems of a broad emission spectrum associated with the BSA Au clusters. Moreover, transferring energy from BSA Au clusters to Dy750 will result in a RET probe with a narrow emission spectrum and long lifetime component which can be utilized in imaging applications.

  9. Fluorescent Sensors for Biological Applications

    Directory of Open Access Journals (Sweden)

    Hui-wang Ai

    2014-09-01

    Full Text Available Fluorescence is one of the most important analytical methods used in biological studies. In the past decade or two, instrumentation in this field has greatly advanced, and now it is possible to detect single photons or fluorescent molecules [1,2], or break the Abbe diffraction limit to distinguish two points spaced less than 50 nm apart [3]. Concurrently, the development of improved fluorescent probes, which can be coupled with state-of-the-art instruments, has been equally important. This special issue on “fluorescent biosensors” in Sensors reports recent results from eight research groups in the field of sensor development. It includes three review articles, and six research articles reporting original results. [...

  10. Fluorescence diagnosis in tissue injury

    Science.gov (United States)

    Maciel, Vitória H.; Ferreira, Juliana; Bagnato, Vanderlei S.

    2009-06-01

    Background and Objectives: The paper aim was to evaluate the efficacy of the fluorescence spectroscopy in the detection of UV-induced skin change of Wistar rats. Study Design/ Materials and Methods: In a group male Wistar rats, the skin damage was produced by an UV-C lamp, periodically monitored using the laser-induced fluorescence, until complete healing process. After determining a characteristic emission band present in the fluorescence spectra of the induced injuries, the amplitude band monitoring allowed the follow up on the injury and the recovery. Results: We observed the appearance of two new emission bands more evident at the injury spectra when compared to the spectrums from normal non-exposed tissue. Following such spectral bands was possible to observe the establishment and recovery. Conclusions: The fluorescence spectroscopy is a promising technique in distinguishing between normal and UV induced skin change helping the evaluation of changes which are irreversible cancer tissue characteristics.

  11. X-ray fluorescence holography

    CERN Document Server

    Hayashi, K; Takahashi, Y

    2003-01-01

    X-ray fluorescence holography (XFH) is a new structural analysis method of determining a 3D atomic arrangement around fluorescing atoms. We developed an XFH apparatus using advanced X-ray techniques and succeeded in obtaining high-quality hologram data. Furthermore, we introduced applications to the structural analysis of a thin film and the environment around dopants and, discussed the quantitative analysis of local lattice distortion. (author)

  12. Fluorescence detection of esophageal neoplasia

    Science.gov (United States)

    Borisova, E.; Vladimirov, B.; Avramov, L.

    2008-06-01

    White-light endoscopy is well-established and wide used modality. However, despite the many technological advances that have been occurred, conventional endoscopy is suboptimal and usually detects advanced stage lesions. The limitations of standard endoscopy initiate development of spectroscopic techniques, additional to standard endoscopic equipment. One of the most sensitive approaches is fluorescence spectroscopy of gastrointestinal mucosa for neoplasia detection. In the recent study delta-aminolevulinic acid/Protoporphyrin IX (5-ALA/PpIX) is used as fluorescent marker for dysplasia and tumor detection in esophagus. The 5-ALA is administered per os six hours before measurements at dose 20 mg/kg weight. Excitation source has max of emission at 405 nm and light is delivered by the standard light guide of the endoscopic equipment. Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer. Spectral features observed during endoscopic investigations could be distinct as the next regions: 450-630 nm region, where tissue autofluorescence is observed; 630-710 nm region, where fluorescence of PpIX is clearly pronounced; 530-580 nm region, where minima in the autofluorescence signal are observed, related to reabsorption of blood. The lack of fluorescence peaks in the red spectral area for normal mucosa is an indication for selective accumulation of 5-ALA/PpIX only in abnormal sites Very good correlation between fluorescence signals and histology examination of the lesions investigated is achieved.

  13. Fluorescence lifetimes: fundamentals and interpretations.

    Science.gov (United States)

    Noomnarm, Ulai; Clegg, Robert M

    2009-01-01

    Fluorescence measurements have been an established mainstay of photosynthesis experiments for many decades. Because in the photosynthesis literature the basics of excited states and their fates are not usually described, we have presented here an easily understandable text for biology students in the style of a chapter in a text book. In this review we give an educational overview of fundamental physical principles of fluorescence, with emphasis on the temporal response of emission. Escape from the excited state of a molecule is a dynamic event, and the fluorescence emission is in direct kinetic competition with several other pathways of de-excitation. It is essentially through a kinetic competition between all the pathways of de-excitation that we gain information about the fluorescent sample on the molecular scale. A simple probability allegory is presented that illustrates the basic ideas that are important for understanding and interpreting most fluorescence experiments. We also briefly point out challenges that confront the experimenter when interpreting time-resolved fluorescence responses.

  14. Size effects in the quantum yield of Cd Te quantum dots for optimum fluorescence bioimaging

    Energy Technology Data Exchange (ETDEWEB)

    Jacinto, C.; Rocha, U.S. [Universidade Federal de Alagoas (UFAL), Maceio, AL (Brazil). Inst. de Fisica. Grupo de Fotonica e Fluidos Complexos; Maestro, L.M.; Garcia-Sole, J.; Jaque, D. [Universidad Autonoma de Madrid (Spain). Dept. de Fisica de Materiales. Fluorescence Imaging Group

    2011-07-01

    Full text: Semiconductor nano-crystals, usually referred as Quantum Dots (QDs) are nowadays regarded as one of the building-blocks in modern photonics. They constitute bright and photostable fluorescence sources whose emission and absorption properties can be adequately tailored through their size. Recent advances on the controlled modification of their surface has made possible the development of water soluble QDs, without causing any deterioration in their fluorescence properties. This has made them excellent optical selective markers to be used in fluorescence bio-imaging experiments. The suitability of colloidal QDs for bio-imaging is pushed forward by their large two-photon absorption cross section so that their visible luminescence (associated to the recombination of electro-hole pairs) can be also efficiently excited under infrared excitation (two-photon excitation). This, in turns, allows for large penetration depths in tissues, minimization of auto-fluorescence and achievement of superior spatial imaging resolution. In addition, recent works have demonstrated the ability of QDs to act as nano-thermometers based on the thermal sensitivity of their fluorescence bands. Based on all these outstanding properties, QDs have been successfully used to mark individual receptors in cell membranes, to intracellular temperature measurements and to label living embryos at different stages. Most of the QD based bio-images reported up to now were obtained by using whether CdSe or CdTe QDs since both are currently commercial available with a high degree of quality. They show similar fluorescence properties and optical performance when used in bio-imaging. Nevertheless, CdTe-QDs have very recently attracted much attention since the hyper-thermal sensitivity of their fluorescence bands was discovered. Based on this, it has been postulated that intracellular thermal sensing with resolutions as large as 0.25 deg C can be achieved based on CdTe-QDs, three times better than

  15. BRIGHT LONG AFTERGLOW PHOSPHORESCENCE GLASS MADE OF SrAl2O4: Eu2+, Dy3+ AND GLASS FRITS

    Institute of Scientific and Technical Information of China (English)

    X.Y. Zhang; Z.F. Cao; L.P. Lu; Z.H. Bai; W.Z. Wang; X.C. Wang

    2005-01-01

    Bright long afterglow phosphorescence glasses were prepared by using SrAl2O4 : Eu2+, Dy3+ phosphors and suitable glass frits together. The SrAl2O4: Eu2+,Dy3+ phosphors were initially prepared by the solid reaction method. Three kinds of glass frits were prepared to match the SrAl2O4: Eu2+,Dy3+ phosphors. Effects of the compositions of the glass frits, the ratios of the phosphors to the frits as well as the firing temperature and firing times on the properties of the samples were discussed. XRD analysis indicated the samples exhibited the typical diffraction peaks of SrAl2O4:Eu2+, Dy3+. The emission spectra of the samples showed broad bands peaking at 510nm. The excitation spectra of the samples showed broad bands ranging from 300 to 480nm. These are believed due to the 5d4f-4f transitions of Eu2+ in the SrAl2O4: Eu2+, Dy3+ phosphors. The afterglow luminescence of the samples excited by a 40W fluorescence lamp for 30min can be observed in the dark for more 10h with the naked eyes. It can find wide applications in many fields.

  16. Statics and dynamics of atomic dark-bright solitons in the presence of impurities

    Energy Technology Data Exchange (ETDEWEB)

    Achilleos, V.; Frantzeskakis, D. J. [Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens GR-157 84 (Greece); Kevrekidis, P. G. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003-4515 (United States); Rothos, V. M. [Department of Mathematics, Physics Computational Sciences, Faculty of Engineering, Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece)

    2011-11-15

    Adopting a mean-field description for a two-component atomic Bose-Einstein condensate, we study the statics and dynamics of dark-bright solitons in the presence of localized impurities. We use adiabatic perturbation theory to derive an equation of motion for the dark-bright soliton center. We show that, counterintuitively, an attractive (repulsive) delta-like impurity, acting solely on the bright-soliton component, induces an effective localized barrier (well) in the effective potential felt by the soliton; this way, dark-bright solitons are reflected from (transmitted through) attractive (repulsive) impurities. Our analytical results for the small-amplitude oscillations of solitons are found to be in good agreement with results obtained via a Bogoliubov-de Gennes analysis and direct numerical simulations.

  17. Detecting gradual visual changes in colour and brightness agnosia: a double dissociation.

    Science.gov (United States)

    Nijboer, Tanja C W; te Pas, Susan F; van der Smagt, Maarten J

    2011-03-01

    Two patients, one with colour agnosia and one with brightness agnosia, performed a task that required the detection of gradual temporal changes in colour and brightness. The results for these patients, who showed anaverage or an above-average performance on several tasks designed to test low-level colour and luminance (contrast) perception in the spatial domain, yielded a double dissociation; the brightness agnosic patient was within the normal range for the coloured stimuli, but much slower to detect brightness differences, whereas the colour agnosic patient was within the normal range for the achromatic stimuli, but much slower for the coloured stimuli. These results suggest that a modality-specific impairment in the detection of gradual temporal changes might be related to, if not underlie, the phenomenon of visual agnosia.

  18. Edge shadow projection method for measuring the brightness of electron guns

    Science.gov (United States)

    Han, Cheolsu; Sul, Inho; Cho, Boklae

    2017-02-01

    The performance of an electron gun is evaluated in terms of the gun brightness. The brightness of an electron gun is typically measured by dividing the angular current density by the virtual source area. An electron gun brightness measurement system was constructed without an electron lens. The system consists of movable apertures (∅ 30, 50, 100, 200 μ m ), a Faraday cup, and a phosphor screen. The Faraday cup is employed to measure the angular current density. The electron beam passes through an aperture and its shade is projected onto the phosphor screen. The virtual source position is determined by measuring the displacement of the aperture shade made by the movement of the aperture. The blurring width of the edge of the shadow on the screen is measured by a charged-coupled device camera to calculate the virtual source size. Brightness values of a tungsten filament electron gun were obtained and compared to reported values.

  19. GPM, AMSR2 GCOMW1 Level 1C Common Calibrated Brightness Temperature VV02A

    Data.gov (United States)

    National Aeronautics and Space Administration — 1CAMSR2 contains common calibrated brightness temperature from the AMSR2 passive microwave instrument flown on the GCOMW1 satellite. This products contains 6 swaths....

  20. GPM, AMSR2 GCOMW1 Level 1C Common Calibrated Brightness Temperature VV03A

    Data.gov (United States)

    National Aeronautics and Space Administration — 1CAMSR2 contains common calibrated brightness temperature from the AMSR2 passive microwave instrument flown on the GCOMW1 satellite. This products contains 6 swaths....