Sample records for affects surface photometry

  1. Stellar Populations Surface photometry

    E-print Network

    Kruit, Piet van der

    Outline Stellar Populations Surface photometry Luminosity distributions Component separation Surface photometry Luminosity distributions Component separation Photometric parameters Elliptical photometry Luminosity distributions Bulge luminosity laws Luminosity distributions in disks Component

  2. Surface photometry STRUCTURE OF GALAXIES

    E-print Network

    Kruit, Piet van der

    Outline Surface photometry Dynamics Formation STRUCTURE OF GALAXIES 9. Elliptical galaxies Piet van van der Kruit, Kapteyn Astronomical Institute Elliptical galaxies #12;Outline Surface photometry Dynamics Formation Outline Surface photometry Luminosity distributions Shells and ripples Color gradients

  3. Galaxy surface photometry

    E-print Network

    Bo Milvang-Jensen; Inger Jorgensen

    2000-04-04

    We describe galaxy surface photometry based on fitting ellipses to the isophotes of the galaxies. Example galaxies with different isophotal shapes are used to illustrate the process, including how the deviations from elliptical isophotes are quantified using Fourier expansions. We show how the definitions of the Fourier coefficients employed by different authors are linked. As examples of applications of surface photometry we discuss the determination of the relative disk luminosities and the inclinations for E and S0 galaxies. We also describe the color-magnitude and color-color relations. When using both near-infrared and optical photometry, the age-metallicity degeneracy may be broken. Finally we discuss the Fundamental Plane where surface photometry is combined with spectroscopy. It is shown how the FP can be used as a sensitive tool to study galaxy evolution.

  4. Surface photometry of NGC 3077

    E-print Network

    Hamed Abdel-Hamid; Peter Notni

    2000-11-03

    We present surface photometry of the irregular galaxy NGC 3077 using two data sets: photographic plates and CCD images. Isophotal contours, luminosity and colour distributions as well as position angle and ellipticity curves show that NGC 3077 is similar to an elliptical galaxy in the outer regions with a disturbed blue centre. The outer isophotes 22-25 mag/arcsec^2 are approximately centred on the dynamical centre, the inner ones are disturbed by the dominant contribution of a reddened young population.

  5. Surface photometry of WINGS galaxies with GASPHOT

    NASA Astrophysics Data System (ADS)

    D'Onofrio, M.; Bindoni, D.; Fasano, G.; Bettoni, D.; Cava, A.; Fritz, J.; Gullieuszik, M.; Kjærgaard, P.; Moretti, A.; Moles, M.; Omizzolo, A.; Poggianti, B. M.; Valentinuzzi, T.; Varela, J.

    2014-12-01

    Aims: We present the B, V, and K band surface photometry catalogs obtained by running the automatic software GASPHOT on galaxies from the WINGS cluster survey with isophotal areas larger than 200 pixels. The catalogs can be downloaded at the Centre de Données Astronomiques de Strasbourg. Methods: The luminosity growth curves of stars and galaxies in a given catalog relative to a given cluster image were obtained simultaneously by slicing the image with a fixed surface brightness step in several SExtractor runs. Then, using a single Sersic law convolved with a space-varying point spread function (PSF), GASPHOT performed a simultaneous ?2 best-fit of the major- and minor-axis luminosity growth curves of galaxies. We outline the GASPHOT performances and compare our surface photometry with that obtained by SExtractor, GALFIT, and GIM2D. This analysis is aimed at providing statistical information about the accuracy that is generally achieved by the softwares for automatic surface photometry of galaxies. Results: The GASPHOT catalogs provide the parameters of the Sersic law that fit the luminosity profiles for each galaxy and for each photometric band. They are the sky coordinates of the galaxy center (RA, Dec), the total magnitude (m), the semi-major axis of the effective isophote (Re), the Sersic index (n), the axis ratio (b/a), and a flag parameter (QFLAG) that generally indicates the fit quality. The WINGS-GASPHOT database includes 41 463 galaxies in the B band, 42 275 in the V band, and 71 687 in the K band. The bright early-type galaxies have higher Sersic indices and larger effective radii, as well as redder colors in their center. In general, the effective radii increase systematically from the K to the V and B band. Conclusions: The GASPHOT photometry agrees well with the surface photometry obtained by GALFIT and GIM2D, and with the aperture photometry provided by SExtractor. In particular, the direct comparison of structural parameters derived by different softwares for common galaxies indicates that the systematic differences are small in general. The only significant deviations are most likely due to the peculiar (and very accurate) image processing adopted by WINGS for large galaxies. The main advantages of GASPHOT with respect to other tools are (i) the automatic finding of the local PSF; (ii) the short CPU execution time; and (iii) the remarkable stability against the choice of the initial-guess parameters. All these characteristics make GASPHOT an ideal tool for blind surface photometry of large galaxy samples in wide-field CCD mosaics. Catalogs are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/572/A87

  6. Surface photometry of comet P/Encke

    NASA Astrophysics Data System (ADS)

    Djorgovski, S.; Spinrad, H.

    1985-05-01

    A scheme to clean cometary digital images from offending background-star trails, and this technique has been applied to a pair of deep Kitt Peak 4-m plates of comet P/Encke, taken in October 1980. Simultaneous and subsequent digital spectra have been obtained at Lick Observatory. The non-polluted coma images show a strong asymmetric sunward-oriented fan/jet, and an extended and rounder (mostly gaseous) main coma, out to approximately 100,000 km radius. The stellar-trail point-spread function has a narrow width (sigma approximately 0.6 arcsec), so that spatial resolution better than approximately 300 km is achieved at the comet. The photometric gradient near the nucleus is very steep, strongly suggesting an icy-grain component which evaporates quickly (at radii equal to or less than 500 km) in the sunlight. Further from the nucleus, the profile becomes shallower, bluer, and more gas dominated. The effect of solar radiation pressure on C2, CN, and other molecules is probably responsible for the rounding of the outer, fainter isophotes. The source of the molecules is likely to be larger than the nucleus itself, and a substantial fraction may originate in the jet. The technique described here may also be applicable in surface photometry of galaxies, in cases where the heavy image pollution by foreground stars is present.

  7. Automated surface photometry for the Coma Cluster galaxies: The catalog

    NASA Technical Reports Server (NTRS)

    Doi, M.; Fukugita, M.; Okamura, S.; Tarusawa, K.

    1995-01-01

    A homogeneous photometry catalog is presented for 450 galaxies with B(sub 25.5) less than or equal to 16 mag located in the 9.8 deg x 9.8 deg region centered on the Coma Cluster. The catalog is based on photographic photometry using an automated surface photometry software for data reduction applied to B-band Schmidt plates. The catalog provides accurate positions, isophotal and total magnitudes, major and minor axes, and a few other photometric parameters including rudimentary morphology (early of late type).

  8. CCD surface photometry of galaxies with dynamical data. II. UBR photometry of 39 elliptical galaxies

    Microsoft Academic Search

    Reynier F. Peletier; Roger L. Davies; L. E. Davis; G. D. Illingworth; Michael Cawson

    1990-01-01

    Intrinsic properties of elliptical galaxies and the mechanisms of their formation and evolution are discussed on the basis of high-precision, multicolor, surface photometry of 39 elliptical galaxies and measurements of rotation curves and velocity dispersion profiles. Using the data collected, a number of correlations between the characteristic parameters of the stellar population of the galaxies have been made to explore

  9. Baltic Astronomy, vol. 8, 535{574, 1999. GALAXY SURFACE PHOTOMETRY

    E-print Network

    Baltic Astronomy, vol. 8, 535{574, 1999. GALAXY SURFACE PHOTOMETRY Bo Milvang-Jensen 1;2 and Inger@gemini.edu Received March 3, 2000 Abstract. We describe galaxy surface photometry based on #12;tting ellipses. As examples of applications of surface photometry we discuss the determination of the relative disk

  10. Changes on Pluto's Surface Revealed with Long Timebase Photometry

    NASA Astrophysics Data System (ADS)

    George, Erin; Buie, M.

    2013-10-01

    We are continuing to monitor the long-term photometric behavior of Pluto in order to constrain volatile surface migration. As Pluto passes near the center of the galaxy, the fields are too crowded for normal aperture photometric techniques. We approached this problem with a combination of point-spread function (PSF) photometry and optimal image subtraction (OIS). Our data are from the 0.8-m robotic telescope at Lowell Observatory, the 1-m robotic telescope at New Mexico State Observatory, and the Faulkes 2-m robotic telescope at Siding Spring, part of Las Cumbres Observatory. Our latest results add photometric data up through 2012 to the data collected since discovery. Our new reduction scheme consists of background catalogs, image subtraction using deep templates, and Pluto photometry extraction. We also use the known photometric properties of Charon determined with HST to remove Charon's contribution from old and new data and compare these results with the HST data where Pluto is measured by itself. Data since 2002 show marked departures from the behavior prior to that time. These results provide clear evidence for time evolution of Pluto's surface albedo. We will present these results along with implications for present-day processes that are altering the surface of Pluto. This work also provides crucial insight into the effort required to provide ground-based support observations for the upcoming New Horizons flyby of Pluto in 2015. Support for this work was provided by NASA Planetary Astronomy Program, grant number NNX09AB43G.

  11. Photographic surface photometry of the Milky Way. II - Surface photometry in the region of the dark cloud 'Coalsack' in U,B,V,R

    NASA Astrophysics Data System (ADS)

    Seidensticker, K. J.; Schmidt-Kaler, T.; Schlosser, W.

    1982-10-01

    Sixteen photographic plates were used to study the surface brightness distribution in UBVR of the Coalsack region of the Galaxy, over an area of 30 x 30 deg centered on l 303 deg, b zero deg, with a resolution of 0.3 deg. During the averaging of all plates of one spectral range, the inner error, or mutual deviation of intensities measured on different plates, was calculated and split into its additive and multiplicative components to facilitate interpretation. The present photometry is compared with the V surface photometry of Smith et al. (1970), the U photometry of Pfleiderer and Mayer (1971), and the B photometries of Mattila (1973) and Classen (1976). The Coalsack is not prominent in any color map, confirming calculations of Mattila (1976), which show that the reddening of dark clouds due to the scattered light is substantially less than the reddening of stars.

  12. K-band Surface Photometry of the Circinus galaxy

    NASA Astrophysics Data System (ADS)

    Park, O.-K.; Freeman, K. C.

    2000-12-01

    NIR K-band mosaic and optical B and I-band images of the Circinus galaxy (SA(s)b, 4 Mpc) were taken to study the large-scale structure and the dust opacity. The K-band mosaic image, covering ~ 10.5' x 4.5' , is the first full-coverage K-band image ever taken for this galaxy. 315 image frames were combined to produce the final mosaic with a total integration time of 15 mins/pixel. With very low dust extinction, this astonishing image clearly reveals the large-scale spiral arms at 220" radius, and a nuclear ring or nuclear spiral sturcture at 15" radius. Although not very distinctive, the oval-shaped bar resides at ~ 50" radius. We will present the first K-band surface photometry results for the Circinus galaxy. OKP acknowledges the financial support as scholarships funded by the Australian National University and the Department of Employment, Education, Training and Youth Affairs (DEETYA) of Australia.

  13. Surface Photometry of Reverberation-Mapped Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Bower, Gary A.

    2015-01-01

    I present a statistical analysis of the surface photometry obtained for a sample of Hubble Space Telescope (HST) archival images of the host galaxies containing active galactic nuclei (AGN), whose time-delay between continuum and broad emission line variations have been analyzed (i.e., reverberation mapping). For quiescent galaxies, strong correlations exist between central black hole mass and host galaxy structure. If there are similar correlations for AGN between central black hole masses derived from reverberation mapping and the host galaxy structure that I have derived from archival HST images, this would imply some validation of the assumptions underlying reverberation mapping concerning the structure, kinematics, and orientation of the broad line regions in AGN.The correlations for quiescent galaxies bewteen central black hole mass and host galaxy structure imply that there might be a strong causal connection between the formation and evolution of the black hole and the galaxy bulge. A current hypothesis is that bulges, black holes, and quasars formed, grew, or turned on as parts of the same process, in part because the collapse or merger of bulges might provide a rich fuel supply to a central black hole. One way of testing this hypothesis would be to plot AGN as a function of redshift on these correlations. However, two severe obstacles limit the ability to measure black hole masses in AGN using HST to analyze the central stellar and/or gas dynamics: (1) since spatial resolution becomes more limited at larger distances, only two reverberation-mapped AGN are close enough to Earth to render the analysis feasible, and (2) it isdifficult to obtain useful spectra of the stars and/or gas in the presence of the bright nonstellar nucleus. The most useful alternative is to exploit reverberation mapping, which uses the time delay in a given AGN between variations in the continuum emission and broad emission lines.

  14. Surface Photometry of the Dwarf Elliptical Galaxies NGC 185 and NGC 205

    E-print Network

    Sang Chul Kim; Myung Gyoon Lee

    1998-06-02

    We present BVRI CCD surface photometry for the central (6'.35 X 6'.35) regions of the dwarf elliptical galaxies NGC 185 and NGC 205 in the Local Group. Surface brightness profiles of NGC 185 (R = 25". The colors of NGC 205 get bluer inward at 1" photometry, supplemented by the photometry based on the far-ultraviolet and visual images of the HST archive data, shows that there is an inversion of color at the very nucleus region (at about 1"). The implications of the redder color of the core part of the nucleus compared with neighboring regions are discussed. The amount of the excess components in the central regions of these galaxies is estimated to be ~10^5 solar luminosity. Distributions of dust clouds in the central regions of the two galaxies are also investigated.

  15. Radiative transfer in the surfaces of atmosphereless bodies. III - Interpretation of lunar photometry

    Microsoft Academic Search

    K. Lumme; W. M. Irvine

    1982-01-01

    Narrowband and UBV photoelectric phase curves of the entire lunar disk and surface photometry of some craters have been interpreted using a newly developed generalized radiative transfer theory for planetary regoliths. The data are well fitted by the theory, yielding information on both macroscopic and microscopic lunar properties. Derived values for the integrated disk geometric albedo are considerably higher than

  16. Deep near-infrared surface photometry and properties of Local Volume dwarf irregular galaxies

    NASA Astrophysics Data System (ADS)

    Young, T.; Jerjen, H.; López-Sánchez, Á. R.; Koribalski, B. S.

    2014-11-01

    We present deep H-band surface photometry and analysis of 40 Local Volume galaxies, a sample primarily composed of dwarf irregulars in the Cen A group, obtained using the Infrared Imager and Spectrograph 2 detector at the 3.9-m Anglo-Australian Telescope. We probe to a surface brightness of ˜25 mag arcsec-2, reaching a 40 times lower stellar density than the Two Micron All Sky Survey (2MASS). Employing extremely careful and rigorous cleaning techniques to remove contaminating sources, we perform surface photometry on 33 detected galaxies deriving the observed total magnitude, effective surface brightness and best-fitting Sérsic parameters. We make image quality and surface photometry comparisons to 2MASS and VISTA Hemisphere Survey demonstrating that deep targeted surveys are still the most reliable means of obtaining accurate surface photometry. We investigate the B - H colours with respect to mass for Local Volume galaxies, finding that the colours of dwarf irregulars are significantly varied, eliminating the possibility of using optical-near-infrared colour transformations to facilitate comparison to the more widely available optical data sets. The structure-luminosity relationships are investigated for our `clean' sample of dwarf irregulars. We demonstrate that a significant fraction of the Local Volume dwarf irregular population have underlying structural properties similar to both Local Volume and Virgo cluster dwarf ellipticals. Linear regressions to structure-luminosity relationships for the Local Volume galaxies and Virgo cluster dwarf ellipticals show significant differences in both slope and scatter around the established trend lines, suggesting that environment might regulate the structural scaling relationships of dwarf galaxies in comparison to their more isolated counterparts.

  17. Planetary surface photometry and imaging: progress and perspectives.

    PubMed

    Goguen, Jay D

    2014-10-01

    Spacecraft have visited and returned many thousands of images and spectra of all of the planets, many of their moons, several asteroids, and a few comet nuclei during the golden age of planetary exploration. The signal in each pixel of each image or spectral channel is a measurement of the radiance of scattered sunlight into a specific direction. The information on the structure and composition of the surface that is contained in variation of the radiance with scattering geometry and wavelength, including polarization state, has only just begun to be exploited and is the topic of this review. The uppermost surfaces of these bodies are mainly composed of particles that are continuously generated by impacts of micrometeoroids and larger impactors. Models of light scattering by distributions of sizes and irregular shapes of particles and by closely packed particles within a surface are challenging. These are active topics of research where considerable progress has recently been made. We focus on the surfaces of bodies lacking atmospheres.These surfaces are diverse and their morphologies give evidence of their evolution by impacts and resurfacing by a variety of processes including down slope movement and electrostatic transport of particles, gravitational accumulation of debris, volatile outgassing and migration, and magnetospheric interactions. Sampling of scattering geometries and spatial resolution is constrained by spacecraft trajectories. However, the large number of archived images and spectra demand more quantitative interpretation. The scattering geometry dependence of the radiance is underutilized and promises constraints on the compositions and structure of the surface for materials that lack diagnostic wavelength dependence. The general problem is considered in terms of the lunar regolith for which samples have been returned to Earth. PMID:25313169

  18. Planetary surface photometry and imaging: progress and perspectives

    NASA Astrophysics Data System (ADS)

    Goguen, Jay D.

    2014-10-01

    Spacecraft have visited and returned many thousands of images and spectra of all of the planets, many of their moons, several asteroids, and a few comet nuclei during the golden age of planetary exploration. The signal in each pixel of each image or spectral channel is a measurement of the radiance of scattered sunlight into a specific direction. The information on the structure and composition of the surface that is contained in variation of the radiance with scattering geometry and wavelength, including polarization state, has only just begun to be exploited and is the topic of this review. The uppermost surfaces of these bodies are mainly composed of particles that are continuously generated by impacts of micrometeoroids and larger impactors. Models of light scattering by distributions of sizes and irregular shapes of particles and by closely packed particles within a surface are challenging. These are active topics of research where considerable progress has recently been made. We focus on the surfaces of bodies lacking atmospheres. These surfaces are diverse and their morphologies give evidence of their evolution by impacts and resurfacing by a variety of processes including down slope movement and electrostatic transport of particles, gravitational accumulation of debris, volatile outgassing and migration, and magnetospheric interactions. Sampling of scattering geometries and spatial resolution is constrained by spacecraft trajectories. However, the large number of archived images and spectra demand more quantitative interpretation. The scattering geometry dependence of the radiance is underutilized and promises constraints on the compositions and structure of the surface for materials that lack diagnostic wavelength dependence. The general problem is considered in terms of the lunar regolith for which samples have been returned to Earth.

  19. Asteroid Photometry

    E-print Network

    Li, Jian-Yang; Buratti, Bonnie J; Takir, Driss; Clark, Beth Ellen

    2015-01-01

    Asteroid photometry has three major applications: providing clues about asteroid surface physical properties and compositions, facilitating photometric corrections, and helping design and plan ground-based and spacecraft observations. The most significant advances in asteroid photometry in the past decade were driven by spacecraft observations that collected spatially resolved imaging and spectroscopy data. In the mean time, laboratory measurements and theoretical developments are revealing controversies regarding the physical interpretations of models and model parameter values. We will review the new developments in asteroid photometry that have occurred over the past decade in the three complementary areas of observations, laboratory work, and theory. Finally we will summarize and discuss the implications of recent findings.

  20. Surface properties and photometry of the Uranian satellites

    NASA Technical Reports Server (NTRS)

    Buratti, Bonnie; Wong, Felicity; Mosher, Joel

    1990-01-01

    Voyager photographic images and photopolarimetric experiment observations have been used to obtain the spectral geometric and Bond albedos, phase integrals, color-dependent phase coefficients, and integrated solar phase-curve parameters of the five Uranian satellites Miranda, Ariel, Umbriel, Titania, and Oberon. While the results obtained confirm those of Nelson et al. (1987) and Veverka et al. (1987) that these five largest Uranian satellites constitute a unique class of low-albedo and spectrally flat objects, attention is presently given to important differences among the five moons' surface physical properties.

  1. Surface Photometry of Star Clusters in the Dwarf Elliptical Galaxies NGC 185 and NGC 205

    E-print Network

    Sang Chul Kim; Myung Gyoon Lee; Doug Geisler; Ata Sarajedini; Taft E. Armandroff; Gary S. Da Costa

    2001-09-14

    We present the surface photometry of star clusters in the nearby dwarf elliptical galaxies NGC 185 and NGC 205, obtained from deep HST WFPC2 F555W (V) and F814W (I) images. We have obtained surface brightness and color profiles of six star clusters in NGC 185, seven star clusters in NGC 205, and one recently discovered non-stellar object in NGC 205. The surface brightness profiles of ten star clusters are fitted well by the King model, and those of four star clusters are fitted well by the power-law. Three out of ten star clusters fitted well with King model show signs of tidal tails.

  2. Empirical correction of Titan surface photometry and atmospheric scattering from Cassini/VIMS data

    NASA Astrophysics Data System (ADS)

    Cornet, T.; Philippe, S.; Le Mouélic, S.; Rodriguez, S.; Sotin, C.; Brown, R. H.; Barnes, J. W.; Baines, K. H.; Buratti, B. J.; Clark, R. N.; Nicholson, P. D.

    2013-12-01

    The Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft is able to image Titan's surface in 7 atmospheric windows in the infrared domain. However, surface photometry, atmospheric scattering and atmospheric absorption effects produce seams and a general blurring effect at short wavelengths in VIMS global mosaics of individual cubes. The aim of this study is therefore to correct empirically the VIMS cubes for atmospheric scattering, absorption and surface photometry, in order to produce seamless albedo maps. We refined the surface photometric correction using a new global mosaic integrating all Titan flybys from Ta to T90. This photometric function corresponds to a Lunar-Lambert law, which in turns allows the estimation of the atmospheric opacity at 5 ?m. This value is consistent with recent values retrieved from solar occultations and specular reflections on North polar lakes. Two approaches to remove the atmospheric scattering are compared in this study. The first one is based on the removal of the atmospheric windows bands wings. The second one is based on band ratios computed on a series of VIMS cubes of the Huygens Landing Site. Albedo values corrected with these methods are consistent with albedo values calculated thanks to complete radiative transfer models established for the Huygens landing site. This confirms the possibility to implement a global first order correction of VIMS cubes in a simple and fast way to obtain the spectral information of the surface.

  3. Surface Photometry and Mass Distribution in the Spiral Galaxies NGC1087 and NGC1090

    NASA Astrophysics Data System (ADS)

    Blackman, C. P.

    1980-02-01

    Photographic surface photometry and rotation curves based on long-slit spectra have been obtained for NGC 1087 and NGC 1090. Both galaxies were originally considered to be members of the Cetus I group, but NGC 1090 has a velocity 5? higher than that of the group so is probably a background object. Total masses and luminosities for the galaxies are 2.7 ± 0.2 × 1010 Msun, 1.4 × 1010 Lsun for NGC l087 and l.l ± 0.2 × 1011 Msun, 2.7 × 1010 Lsun for NGC l090, where H0 = 100 h km s-1 Mpc-1. NGC l094/ANON, apparently in the same group, are a background binary pair with combined masses > 9.4 × 1010 h-1 Msun and luminosities of 5.4 × 1010 Lsun.

  4. Disk Galaxies in the Outer Local Supercluster: Optical CCD Surface Photometry and Distribution of Galaxy Disk Parameter

    NASA Technical Reports Server (NTRS)

    Lu, N. Y.

    1998-01-01

    We report new B-band CCD surface photometry on a sample of 76 disk galaxies brighter than BT = 14.5 mag in the Uppsala General Catalogue of Galaxies, which are confined within a volume located in the outer part of the Local Supercluster.

  5. HST observations of globular clusters in M 31. 1: Surface photometry of 13 objects

    NASA Technical Reports Server (NTRS)

    Pecci, F. Fusi; Battistini, P.; Bendinelli, O.; Bonoli, F.; Cacciari, C.; Djorgovski, S.; Federici, L.; Ferraro, F. R.; Parmeggiani, G.; Weir, N.

    1994-01-01

    We present the initial results of a study of globular clusters in M 31, using the Faint Object Camera (FOC) on the Hubble Space Telescope (HST). The sample of objects consists of 13 clusters spanning a range of properties. Three independent image deconvolution techniques were used in order to compensate for the optical problems of the HST, leading to mutually fully consistent results. We present detailed tests and comparisons to determine the reliability and limits of these deconvolution methods, and conclude that high-quality surface photometry of M 31 globulars is possible with the HST data. Surface brightness profiles have been extracted, and core radii, half-light radii, and central surface brightness values have been measured for all of the clusters in the sample. Their comparison with the values from ground-based observations indicates the later to be systematically and strongly biased by the seeing effects, as it may be expected. A comparison of the structural parameters with those of the Galactic globulars shows that the structural properties of the M 31 globulars are very similar to those of their Galactic counterparts. A candidate for a post-core-collapse cluster, Bo 343 = G 105, has been already identified from these data; this is the first such detection in the M 31 globular cluster system.

  6. DEEP K{sub s} -NEAR-INFRARED SURFACE PHOTOMETRY OF 80 DWARF IRREGULAR GALAXIES IN THE LOCAL VOLUME

    SciTech Connect

    Fingerhut, Robin L.; McCall, Marshall L.; Argote, Mauricio [Department of Physics and Astronomy, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3 (Canada); Cluver, Michelle E. [IPAC, California Institute of Technology, MC 220-6, Pasadena, CA 91106 (United States); Nishiyama, Shogo [Department of Astronomy, Kyoto University Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Rekola, Rami T. F. [Tuorla Observatory, Department of Physics and Astronomy, University of Turku, FI-21500 Piikkioe (Finland); Richer, Michael G. [Instituto de Astronomia, Universidad Autonoma de Mexico, P.O. Box 439027, San Diego, CA 92143 (United States); Vaduvescu, Ovidiu [Isaac Newton Group of Telescopes, Apartado 321, E-38700 Santa Cruz de La Palma (Spain); Woudt, Patrick A., E-mail: rfinger@yorku.c, E-mail: mccall@yorku.c, E-mail: argote@yorku.c, E-mail: mcluver@ipac.caltech.ed, E-mail: shogo@kusastro.kyoto-u.ac.j, E-mail: rareko@utu.f, E-mail: richer@astrosen.unam.m, E-mail: ovidiuv@ing.iac.e, E-mail: pwoudt@ast.uct.ac.z [Department of Astronomy, University of Cape Town, Rondebosch 7700 (South Africa)

    2010-06-10

    We present deep near-infrared (K{sub s}) images and surface photometry for 80 dwarf irregular galaxies (dIs) within {approx}5 Mpc of the Milky Way. The galaxy images were obtained at five different facilities between 2004 and 2006. The image reductions and surface photometry have been performed using methods specifically designed for isolating faint galaxies from the high and varying near-infrared sky level. Fifty-four of the 80 dIs have surface brightness profiles which could be fit to a hyperbolic-secant (sech) function, while the remaining profiles could be fit to the sum of a sech and a Gaussian function. From these fits, we have measured central surface brightnesses, scale lengths, and integrated magnitudes. This survey is part of a larger study of the connection between large-scale structure and the global properties of dIs, the hypothesized building-blocks of more massive galaxies.

  7. The structure and dynamics of ringed galaxies. III - Surface photometry and kinematics of the ringed nonbarred spiral NGC 7531

    Microsoft Academic Search

    R. Buta

    1987-01-01

    The photometric and kinematic properties of the southern galaxy NGC 7531, a large example of a nonbarred spiral possessing a very bright inner ring, are explored via UVBRI surface photometry and emission-line spectroscopy. The galaxy is a global, two-armed spiral galaxy possessing a bright inner ring with a radius of 2.3 kpc. The ring has an average surface brightness in

  8. Stellar populations in edge-on galaxies from deep CCD surface photometry, 1: NGC 5907

    NASA Technical Reports Server (NTRS)

    Morrison, Heather L.; Boroson, Todd A.; Harding, Paul

    1994-01-01

    We present extremely deep charge coupled device (CCD) surface photometry of the edge-on Sc galaxy NGC 5907. Our data reach reliably to a surface brightness of R=27 mag/sq arcsec, some two magnitudes fainter than any previous work. We obtained this improvement using a 2048X2048 CCD with a wide (approximately 24 min) field, which made it possible to sky subtract directly from the galaxy frame, and by taking many dark sky flatfields. Our analysis of these data, using a full 2D model fitting procedure with a detailed error model, confirm the thin disk parameters of van der Kruit & Searle (1981). In particular, we confirm that the galaxy's disk has a radial cutoff and a constant scale height with radius. We find evidence for a stellar warp in this system, which has the same orientation as the H I warp. Our deep data also confirm that NGC 5907 has no thick disk. This suggests that theories of thick disk formation from star formation in the early stages of disk collapse, or by secular heating mechanisms, are unlikely to be correct, because they would predict that every galaxy would have a thick disk. Thick disk formation from the accretion of satellite galaxies is more likely.

  9. UIT: Ultraviolet surface photometry of the spiral galaxy M74 (NGC 628)

    NASA Technical Reports Server (NTRS)

    Cornett, Robert H.; O'Connell, Robert W.; Greason, Michael R.; Offenberg, Joel D.; Angione, Ronald J.; Bohlin, Ralph C.; Cheng, K. P.; Roberts, Morton S.; Smith, Andrew M.; Smith, Eric P.

    1994-01-01

    Ultraviolet photometry, obtained from Ultraviolet Imaging Telescope (UIT) images at 1520 A (far-UV; magnitudes m(152)) and 2490 A (near-UV; magnitudes m(249)), of the spiral galaxy M74 (NGC 628) is compared with H-alpha, R, V, and B surface photometry and with models. M74's surface brightness profiles have a central peak with an exponential falloff; the exponential scale lengths of the profiles increase with decreasing wavelength for the broad-band images. The slope of the continuum-subtracted H-alpha profile is intermediate between those of far-UV and near-UV profiles, consistent with the related origins of H-alpha and UV emission in extreme Population I material. M74's color profiles all become bluer with increasing radius. The (m(152) - m(249)) color as measured by UIT averages near 0.0 (the color of an A0 star) over the central 20 sec radius and decreases from approximately -0.2 to approximately -0.4 from 20 sec to 200 sec. The spiral arms are the dominant component of the surface photometry colors; interarm regions are slightly redder. In the UV, M74's nuclear region resembles its disk/spiral arm material in colors and morphology, unlike galaxies such as M81. No UV 'bulge' is apparent. The m(152) - m(249) colors and models of M74's central region clearly demonstrate that there is no significant population of O or B stars present in the central 10 sec. M74's UV morphology and (m(152) - m(249)) color profiles are similar to those of M33, although M74 is approximately 0.5 mag redder. M81 has a smooth UV bulge which is much redder than the nuclear regions of M74 and M33. M74 is approximately 0.4 mag bluer than M81 in its outer disk, although M81 has bright UV sources only in spiral arms more than 5 kpc from its center. We investigate possible explanations for the color profiles of the galaxies and the differences among the galaxies: abundances; reddening due to internal dust; interplanetary magnetic field (IMF) variations, and the history of formation of the dominant generations of stars. Abundance and IMF variations do not produce large enough m(152) - m(249) or UV - V color differences. Comparing model UV/optical colors with those of M74 shows that M74's disk has undergone significant star formation over the past 500 Myr, and that either the star-formation history or the extinction varies systematically across M74's disk. Comparison of M74, M33, and M81 (UV - V) colors shows that M74 colors range from the bluest of M33's colors to the bluest of M81's. The failure of reddening models to cover the range of colors, and the known abundance range in such material, leads to the conclusion that star-formation history varies significantly as a function of radius in these galaxies, and that such variation is required to explain the range of colors observed in M74, M33, and M81.

  10. THE MID-INFRARED TULLY-FISHER RELATION: SPITZER SURFACE PHOTOMETRY

    SciTech Connect

    Sorce, Jenny G.; Courtois, Helene M. [Universite Claude Bernard Lyon 1, Institut de Physique Nucleaire, Lyon (France); Tully, R. Brent, E-mail: j.sorce@ipnl.in2p3.fr [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, HI 96822 (United States)

    2012-11-01

    The availability of photometric imaging of several thousand galaxies with the Spitzer Space Telescope enables a mid-infrared calibration of the correlation between luminosity and rotation in spiral galaxies. The most important advantage of the new calibration in the 3.6 {mu}m band, IRAC Channel 1, is photometric consistency across the entire sky. Additional advantages are minimal obscuration, observations of flux dominated by old stars, and sensitivity to low surface brightness levels due to favorable backgrounds. Roughly 3000 galaxies have been observed through Spitzer cycle 7 and images of these are available from the Spitzer archive. In cycle 8, a program called Cosmic Flows with Spitzer was initiated, which will increase the available sample of spiral galaxies with inclinations greater than 45 Degree-Sign from face-on that are suitable for distance measurements by 1274. This paper describes procedures, based on the photometry package Archangel, that are being employed to analyze both the archival and new data in a uniform way. We give results for 235 galaxies, our calibrator sample for the Tully-Fisher relation. Galaxy magnitudes are determined with uncertainties held below 0.05 mag for normal spiral systems. A subsequent paper will describe the calibration of the [3.6] luminosity-rotation relation.

  11. LROC NAC Photometry as a Tool for Studying Physical and Compositional Properties of the Lunar Surface

    NASA Astrophysics Data System (ADS)

    Clegg, R. N.; Jolliff, B. L.; Boyd, A. K.; Stopar, J. D.; Sato, H.; Robinson, M. S.; Hapke, B. W.

    2014-10-01

    LROC NAC photometry has been used to study the effects of rocket exhaust on lunar soil properties, and here we apply the same photometric methods to place compositional constraints on regions of silicic volcanism and pure anorthosite on the Moon.

  12. Photometric calibration of NGS/POSS and ESO/SRC plates using the NOAO PDS measuring engine. II - Surface photometry

    NASA Technical Reports Server (NTRS)

    Cutri, Roc M.; Low, Frank J.; Guhathakurta, Puragra

    1993-01-01

    In this paper we present a method to calibrate surface photometry of faint sources measured from direct photographic plates, such as those of the NGS/POSS and ESO/SRC Sky Survey. This calibration procedure does not require scanning sensitometer spots on the plates, but instead uses measurements of the brightness profiles of many faint stars of known brightness to fit a linearized approximation to the characteristic curve. The approximation is valid for only low- to medium-density emulsions, so this technique is appropriate only for relatively faint emission. Comparison between measurements of representative extended sources on the NGS/POSS and CCD images indicates that surface photometry can be obtained from the Sky Survey plates accurate to 0.1-0.3 mag in the range mu(B) between 23 and 27 and mu(R) between 22 and 26 mag/sq arcsec.

  13. Effect of surface conditions affecting voltage breakdowns

    NASA Astrophysics Data System (ADS)

    Flauta, Randolph; Aghazarian, Maro; Caughman, John; Ruzic, David

    2008-11-01

    The maximum power transferred by ion cyclotron range of frequency (ICRF) antennas is dependent on the breakdown threshold when operated at high voltages. The voltage that these antennas can withstand is lowered and hence breakdowns occur due to many factors. The Surface Plasma Arcs by Radiofrequency - Control Study or SPARCS facility has a 0-15kV DC power supply to deliver power to flat cathode surface and semi-spherical anode made of Cu and Al under 10-8-10-6 torr vacuum conditions. The effects of different surface conditions on the breakdown threshold were then investigated. Also, as the ICRF antennas used for heating plasmas may come into contact with contaminants from the plasma, Li was also deposited on the cathode surface through in-situ evaporation coating and its effect on the breakdown threshold was investigated. Results on surface roughness showed no significant dependence of the breakdown threshold on macroscopic surface roughness in the cathode arithmetic roughness range of ˜77-1139nm. Microscopic surface features such as grain boundaries, impurities and imperfections may play a more visible role in affecting the vacuum breakdown.

  14. Cylinder surface, temperature may affect LPG odorization

    SciTech Connect

    McWilliams, H.

    1988-01-01

    A study of possible odorant fade in propane by the Arthur D. Little Co. (Boston) has indicated that oxidation of interior surfaces of LPG containers may cause the odorant, ethyl mercaptan, to fade. The oxidation, ferous oxide, is a black, easily oxidizable powder that is the monoxide of iron. The study, contracted for by the Consumer Product Safety Commission (CPSC), is part of that agency's study of residential LP-gas systems. Another study is currently underway by an NLPGA task force headed by Bob Reid of Petrolane (Long Beach, Calif.). It may not be finished until the end of next year. Recently, the Propane Gas Association of Canada completed a study of odorant fade with the conclusion that much more study is needed on the subject. In addition to the cylinder surface problem, the CPSC study indicated that ambient temperatures might also affect the presence of odorant in product. This article reviews some of the results.

  15. How membrane surface affects protein structure.

    PubMed

    Bychkova, V E; Basova, L V; Balobanov, V A

    2014-12-01

    The immediate environment of the negatively charged membrane surface is characterized by decreased dielectric constant and pH value. These conditions can be modeled by water-alcohol mixtures at moderately low pH. Several globular proteins were investigated under these conditions, and their conformational behavior in the presence of phospholipid membranes was determined, as well as under conditions modeling the immediate environment of the membrane surface. These proteins underwent conformational transitions from the native to a molten globule-like state. Increased flexibility of the protein structure facilitated protein functioning. Our experimental data allow understanding forces that affect the structure of a protein functioning near the membrane surface (in other words, in the membrane field). Similar conformational states are widely reported in the literature. This indicates that the negatively charged membrane surface can serve as a moderately denaturing agent in the cell. We conclude that the effect of the membrane field on the protein structure must be taken into account. PMID:25749161

  16. Near-infrared and optical broadband surface photometry of 86 face-on disk dominated galaxies. IV. Using color profiles to study stellar and dust content of galaxies

    Microsoft Academic Search

    R. S. de Jong

    1996-01-01

    The stellar and dust content of spiral galaxies as function of radius has been investigated using near-infrared and optical broadband surface photometry of 86 face-on spiral galaxies. Colors of galaxies correlate with the azimuthally averaged local surface brightness both within and among galaxies, with the lower surface brightness regions being bluer. The colors formed from different passband combinations correlate strongly

  17. Near-infrared and optical broadband surface photometry of 86 face-on disk dominated galaxies. IV. Using color profiles to study stellar and dust content of galaxies

    Microsoft Academic Search

    Roelof S. de Jong

    1996-01-01

    The stellar and dust content of spiral galaxies as function of radius has\\u000abeen investigated using near-infrared and optical broadband surface photometry\\u000aof 86 face-on spiral galaxies. Colors of galaxies correlate with the\\u000aazimuthally averaged local surface brightness both within and among galaxies,\\u000awith the lower surface brightness regions being bluer. The colors formed from\\u000adifferent passband combinations correlate strongly

  18. BVRI-H? surface photometry of peculiar ring galaxies. I. HRG 2302

    NASA Astrophysics Data System (ADS)

    Myrrha, M. L. M.; Vaz, L. P. R.; Faúndez-Abans, M.; de Oliveira-Abans, M.; Soares, D. S. L.

    1999-11-01

    Detailed BVRI-H? photometry has been obtained for the ring galaxy HRG 2302. This is probably a still interacting system which shows two principal components: the target, which is a knotted ringed-disk, and the intruder, an elongated galaxy with two substructures probably caused by the interaction. The existence of H II emission regions is suggested by H? images and medium dispersion spectra of the three brightest parts of this system. Analysis of a color-color diagram suggests recent star formation, in agreement with the behavior of interacting galaxies with nuclear emission. HRG 2302 has been previously classified as a Polar Ring galaxy (Faúndez-Abans & de Oliveira-Abans te{fa8a}), but we have reclassified it as Elliptical-Knotted, based on the morphological substructures found. This work reveals, for the first time, the existence of at least 15 fainter galaxies in the field within ~ 4arcmin around HRG 2302, giving positions and integrated standard magnitudes for all of them. Based on observations made at the Observatório do Pico dos Dias (OPD), operated by the MCT/CNPq/Laboratório Nacional de Astrofísica, in the state of Minas Gerais, Brazil

  19. Titan: Preliminary results on surface properties and photometry from VIMS observations of the early flybys

    USGS Publications Warehouse

    Buratti, B.J.; Sotin, C.; Brown, R.H.; Hicks, M.D.; Clark, R.N.; Mosher, J.A.; McCord, T.B.; Jaumann, R.; Baines, K.H.; Nicholson, P.D.; Momary, T.; Simonelli, D.P.; Sicardy, B.

    2006-01-01

    Cassini observations of the surface of Titan offer unprecedented views of its surface through atmospheric windows in the 1-5 ??m region. Images obtained in windows for which the haze opacity is low can be used to derive quantitative photometric parameters such as albedo and albedo distribution, and physical properties such as roughness and particle characteristics. Images from the early Titan flybys, particularly T0, Ta, and T5 have been analyzed to create albedo maps in the 2.01 and 2.73 ??m windows. We find the average normal reflectance at these two wavelengths to be 0.15??0.02 and 0.035??0.003, respectively. Titan's surface is bifurcated into two albedo regimes, particularly at 2.01 ??m. Analysis of these two regimes to understand the physical character of the surface was accomplished with a macroscopic roughness model. We find that the two types of surface have substantially different roughness, with the low-albedo surface exhibiting mean slope angles of ???18??, and the high-albedo terrain having a much more substantial roughness with a mean slope angle of ???34??. A single-scattering phase function approximated by a one-term Henyey-Greenstein equation was also fit to each unit. Titan's surface is back-scattering (g???0.3-0.4), and does not exhibit substantially different backscattering behavior between the two terrains. Our results suggest that two distinct geophysical domains exist on Titan: a bright region cut by deep drainage channels and a relatively smooth surface. The two terrains are covered by a film or a coating of particles perhaps precipitated from the satellite's haze layer and transported by eolian processes. Our results are preliminary: more accurate values for the surface albedo and physical parameters will be derived as more data is gathered by the Cassini spacecraft and as a more complete radiative transfer model is developed from both Cassini orbiter and Huygens Lander measurements. ?? 2006 Elsevier Ltd. All rights reserved.

  20. Optics on a fractal surface and the photometry of the regoliths

    NASA Astrophysics Data System (ADS)

    Drossart, P.

    1993-05-01

    The light scattered by a rough surface is calculated in a model where the surface is simulated by a mathematical fractal of dimension (D(H) between 2 and 3) and fractal density in the projected area towards the observer rho(H) (rho(H) between 0 and 1). The reflectance on such a surface is calculated in the special case of a 'hemispherical' fractal, in both the geometric optics approximation and a more general diffraction regime. By using a two-parameter phase function (single scattering albedo omega-sub-0 and asymmetry parameter g-sub-0), and including multiple scattering, this four-parameter model is found to reproduce within a good accuracy the phase function of several classes of atmosphereless bodies in the solar system, in good agreement with previous photometric models. The main effect of the diffraction is to reduce the width of the opposition surge by roughly a factor of 2. Another prediction of the model is that the single-scattering contribution due to the fractal part of the surface can be reduced, for nonzero phase angle, to an arbitrarily small amount, for high enough fractal dimension and density. This effect could give a new interpretation of the strong opposition effect observed on some objects, and also of the very low brightness of many solar system bodies.

  1. Near-infrared observations of galaxies in Pisces-Perseus. I. vec H-band surface photometry of 174 spiral

    NASA Astrophysics Data System (ADS)

    Moriondo, G.; Baffa, C.; Casertano, S.; Chincarini, G.; Gavazzi, G.; Giovanardi, C.; Hunt, L. K.; Pierini, D.; Sperandio, M.; Trinchieri, G.

    1999-05-01

    We present near-infrared, H-band (1.65 $() ?m), surface photometry of 174 spiral galaxies in the area of the Pisces-Perseus supercluster. The images, acquired with the ARNICA camera mounted on various telescopes, are used to derive radial profiles of surface brightness, ellipticities, and position angles, together with global parameters such as H-band magnitudes and diameters Radial profiles in tabular form and images FITS files are also available upon request from gmorio@arcetri.astro.it.}. The mean relation between H-band isophotal diameter D_{21.5} and the B-band D25 implies a B-H color of the outer disk bluer than 3.5; moreover, D_{21.5}/D25 depends on (global) color and absolute luminosity. The correlations among the various photometric parameters suggest a ratio between isophotal radius D_{21.5}/2 and disk scale length of ~ m3.5 and a mean disk central brightness ~ meq 17.5 H-mag arcsec^{-2}. We confirm the trend of the concentration index C31$ with absolute luminosity and, to a lesser degree, with morphological type. We also assess the influence of non-axisymmetric structures on the radial profiles and on the derived parameters. Based on observations at the TIRGO, NOT, and VATT telescopes. TIRGO (Gornergrat, CH) is operated by CAISMI-CNR, Arcetri, Firenze. NOT (La Palma, Canary Islands) is operated by NOTSA, the Nordic Observatory Scientific Association. VATT (Mt. Graham, Az) is operated by VORG, the Vatican Observatory Research Group Table 3 and Fig. 4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html.

  2. Deep multiband surface photometry on a sample of 24 blue compact galaxies - I

    NASA Astrophysics Data System (ADS)

    Micheva, Genoveva; Östlin, Göran; Bergvall, Nils; Zackrisson, Erik; Masegosa, Josefa; Marquez, Isabel; Marquart, Thomas; Durret, Florence

    2013-05-01

    We present deep optical and near-infrared (NIR) UBVRIHKs imaging data for 24 blue compact galaxies (BCGs). The individual exposure times are on average ˜40 min in the optical (B) and ˜90 min in the NIR, but on occasion up to ˜5 h for a single target and filter, observed with 2.5, 3.5, 8.2-m telescopes. The sample contains luminous dwarf and intermediate-mass BCGs which are predominantly metal poor, although a few have near-solar metallicities. We have analysed isophotal and elliptical integration surface brightness and colour profiles, extremely deep (?B ? 29 mag arcsec-2) contour maps and RGB images for each galaxy in the sample, and provide a morphological classification where such is missing. Separating the burst from the underlying host we find that regardless of the total luminosity the host galaxy has the properties of a low surface brightness (LSB) dwarf with MB ? -18. For a number of galaxies we discover a distinct LSB component dominant around and beyond the Holmberg radius. For the specific case of ESO 400-43A&B we detect an optical bridge between the two companion galaxies at the ?V ˜ 28th mag arcsec-2 isophotal level. Synthetic disc tests are performed to verify that we can trace such faint components with negligible errors down to ?B = 28 and ?K = 23 mag arcsec-2. By examining the structural parameters (central surface brightness ?0 and scalelength hr) derived from two radial ranges typically assumed to be dominated by the underlying host galaxy, we demonstrate the importance of sampling the host well away from the effects of the burst. We find that ?0 and hr of the BCGs host deviate from those of dwarf ellipticals (dEs) and dwarf irregulars (dI) solely due to a strong burst contribution to the surface brightness profile almost down to the Holmberg radius. Structural parameters obtained from a fainter region, ?B = 26-28 mag arcsec-2, are consistent with those of true LSB galaxies for the starbursting BCGs in our sample, and with dEs and dIs for the BCGs with less vigorous star formation.

  3. Basics of Photometry Photometry: Basic Questions

    E-print Network

    Masci, Frank

    Basics of Photometry #12;Photometry: Basic Questions · How do you identify objects in your image type of object you're studying? #12;#12;#12;Topics 1. General Considerations 2. Stellar Photometry 3. Galaxy Photometry #12;I: General Considerations 1. Garbage in, garbage out... 2. Object Detection 3

  4. Surface Photometry and Metallicity of the Polar Ring Galaxy A0136-0801

    E-print Network

    Spavone, Marilena; Arnaboldi, Magda

    2015-01-01

    We present a photometric and spectroscopic study of the polar ring galaxy A0136-0801 in order to constrain its formation history. Near-Infrared (NIR) and optical imaging data are used to extract surface brightness and color profiles of the host galaxy and the wide polar structure in A0136-0801. The host galaxy dominates the light emission in all bands; the polar structure is more luminous in the optical bands and is three times more extended than the main spheroid. The average stellar population in the spheroid is redder than in the polar structure and we use their (B-K) vs. (J-K) colors to constraint the ages of these populations using stellar population synthesis models. The inferred ages are 3-5 Gyrs for the spheroid and 1-3 Gyrs for the polar structure. We then use long slit spectra along the major axis of the polar structure to derive the emission line ratios and constrain the oxygen abundance, metallicity and star formation rate in this component. We find 12+log(O/H) = 8.33 +- 0.43 and Z ~ 0.32 Zsun, us...

  5. How surface roughness affects chemical transfer from soil to surface runoff?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil surface roughness affects transport processes, e.g., runoff generation, infiltration, sediment detachment, etc., occurring on the surface. Nevertheless, how soil roughness affects chemical transport is less known. In this study, we partitioned roughness elements into mounds which diverge water ...

  6. Activities affecting surface water resources: A general overview

    SciTech Connect

    Not Available

    1990-01-01

    In November 1987, P.E.I. signed a federal/provincial work-sharing arrangement on water resource management focusing on groundwater pollution, surface water degradation and estuarine eutrophication. The surface water program was designed to identify current surface water uses and users within 12 major watersheds across the Island containing 26 individual rivers, as well as problems arising due to practices that degrade the quality of surface water and restricts its value to other user groups. This report presents a general overview of the program, covering the general characteristics of the Island; operations in agriculture, fish and wildlife, forestry, recreation, fisheries, and industry; alterations of natural features of waterways; wetlands; additional watershed activities such as hydrometric stations and subdivision development; and activities affecting surface water resources such as sedimentation sources, pollution point sources and instream obstructions.

  7. Context affects lightness at the level of surfaces.

    PubMed

    Maertens, Marianne; Wichmann, Felix A; Shapley, Robert

    2015-01-01

    Visual perception of object attributes such as surface lightness is crucial for successful interaction with the environment. How the visual system assigns lightness to image regions is not yet understood. It has been shown that the context in which a surface is embedded influences its perceived lightness, but whether that influence involves predominantly low-, mid-, or high-level visual mechanisms has not been resolved. To answer this question, we measured whether perceptual attributes of target image regions affected their perceived lightness when they were placed in different contexts. We varied the sharpness of the edge while keeping total target flux fixed. Targets with a sharp edge were consistent with the perceptual interpretation of a surface, and in that case, observers perceived significant brightening or darkening of the target. Targets with blurred edges rather appeared to be spotlights instead of surfaces; for targets with blurred edges, there was much less of a contextual effect on target lightness. The results indicate that the effect of context on the lightness of an image region is not fixed but is strongly affected by image manipulations that modify the perceptual attributes of the target, implying that a mid-level scene interpretation affects lightness perception. PMID:25589299

  8. ARCHANGEL: Galaxy Photometry System

    NASA Astrophysics Data System (ADS)

    Schombert, James

    2011-07-01

    ARCHANGEL is a Unix-based package for the surface photometry of galaxies. While oriented for large angular size systems (i.e. many pixels), its tools can be applied to any imaging data of any size. The package core contains routines to perform the following critical galaxy photometry functions: sky determinationframe cleaningellipse fittingprofile fittingtotal and isophotal magnitudes The goal of the package is to provide an automated, assembly-line type of reduction system for galaxy photometry of space-based or ground-based imaging data. The procedures outlined in the documentation are flux independent, thus, these routines can be used for non-optical data as well as typical imaging datasets. ARCHANGEL has been tested on several current OS's (RedHat Linux, Ubuntu Linux, Solaris, Mac OS X). A tarball for installation is available at the download page. The main routines are Python and FORTRAN based, therefore, a current installation of Python and a FORTRAN compiler are required. The ARCHANGEL package also contains Python hooks to the PGPLOT package, an XML processor and network tools which automatically link to data archives (i.e. NED, HST, 2MASS, etc) to download images in a non-interactive manner.

  9. Surface analysis, ion implantation and tribological processes affecting steels

    NASA Astrophysics Data System (ADS)

    Singer, Irwin L.

    1984-05-01

    An analytical approach is presented for investigating surface processing treatments used to improve the friction and wear (i.e., tribological) behavior of engineering alloys, with specific examples cited for ion implantation of steels. Surface composition techniques such as scanning Auger microscopy, energy dispersive X-ray analysis and secondary ion mass spectroscopy and microscopies such as transmission electron microscopy (TEM), secondary electron microscopy and interferometry have eluciated the microstructure and chemistry of a variety of implant species (N, C, Ti and Ta) found to affect the tribological behavior of surfaces. Novel combinations of these techniques, along with metallography of ion-etched surfaces or TEM of ion-beam-etched foils, are shown to be useful methods for establishing microstructures of ion-implanted and worn surfaces. The tribological behavior of the thin implanted layer (˜ 200 nm) is examined by two devices: a stickslip machine and a polishing wear apparatus, the latter having wear rate versus depth resolution of 10 to 20 nm. Tribology studies of two implanted steels, 304 stainless steel and 52100 bearing steel, are presented, and analytical investigations which have led to models for their improved wear behavior are described. A process by which implanted metal ions can react with residual gases in the vacuum chamber to "carburize" steel and produce superior tribological surfaces is also discussed.

  10. How a Change in Water Phase Affects Surface Temperatures

    NSDL National Science Digital Library

    In this problem-based learning (PBL) activity, students take on the role of a student research scientist and explore the role of solar energy in determining climate. Students conduct experiments to observe how a change in water phase affects surface temperatures. Materials required for the investigation include 2 aquariums, dry sand or soil, two heat lamps, and two thermometers.The lesson is supported by teacher notes, answer key, glossary and an appendix with information about using PBL in the classroom. This is the second of three activities in Investigating the Climate System: Energy, a Balancing Act.

  11. How does stratospheric variability affect surface weather and climate?

    NASA Astrophysics Data System (ADS)

    Baldwin, Mark; Birner, Thomas

    2013-04-01

    Changes to the stratosphere, due to both natural variability and ozone depletion, have substantial effects on surface weather and climate, especially at middle to high latitudes. Despite clear evidence of these impacts, the primary dynamics of this phenomenon are not yet well understood. Here we show that the stratospheric meridional circulation forces the column of air above the Arctic downwards into the troposphere, acting like a mechanical plunger that controls the day-to-day thickness of the troposphere. This vertical motion directly affects temperatures and the strength of jets in the mid- to upper troposphere. Raising and lowering of the Arctic tropopause layer leads to stretching and compression of the tropospheric column and a north-south dipole in surface pressure similar to the Northern Annular Mode.

  12. Nanocontact electrification: patterned surface charges affecting adhesion, transfer, and printing.

    PubMed

    Cole, Jesse J; Barry, Chad R; Knuesel, Robert J; Wang, Xinyu; Jacobs, Heiko O

    2011-06-01

    Contact electrification creates an invisible mark, overlooked and often undetected by conventional surface spectroscopic measurements. It impacts our daily lives macroscopically during electrostatic discharge and is equally relevant on the nanoscale in areas such as soft lithography, transfer, and printing. This report describes a new conceptual approach to studying and utilizing contact electrification beyond prior surface force apparatus and point-contact implementations. Instead of a single point contact, our process studies nanocontact electrification that occurs between multiple nanocontacts of different sizes and shapes that can be formed using flexible materials, in particular, surface-functionalized poly(dimethylsiloxane) (PDMS) stamps and other common dielectrics (PMMA, SU-8, PS, PAA, and SiO(2)). Upon the formation of conformal contacts and forced delamination, contacted regions become charged, which is directly observed using Kelvin probe force microscopy revealing images of charge with sub-100-nm lateral resolution. The experiments reveal chemically driven interfacial proton exchange as the dominant charging mechanism for the materials that have been investigated so far. The recorded levels of uncompensated charges approach the theoretical limit that is set by the dielectric breakdown strength of the air gap that forms as the surfaces are delaminated. The macroscopic presence of the charges is recorded using force-distance curve measurements involving a balance and a micromanipulator to control the distance between the delaminated objects. Coulomb attraction between the delaminated surfaces reaches 150 N/m(2). At such a magnitude, the force finds many applications. We demonstrate the utility of printed charges in the fields of (i) nanoxerography and (ii) nanotransfer printing whereby the smallest objects are ?10 nm in diameter and the largest objects are in the millimeter to centimeter range. The printed charges are also shown to affect the electronic properties of contacted surfaces. For example, in the case of a silicon-on-insulator field effect transistors are in contact with PDMS and subsequent delamination leads to threshold voltage shifts that exceed 500 mV. PMID:21526803

  13. 1.65 ?m (H-band) surface photometry of galaxies. III. observations of 558 galaxies with the TIRGO 1.5 m telescope

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Franzetti, P.; Scodeggio, M.; Boselli, A.; Pierini, D.; Baffa, C.; Lisi, F.; Hunt, L. K.

    2000-02-01

    We present near-infrared H-band (1.65 ?m ) surface photometry of 558 galaxies in the Coma Supercluster and in the Virgo cluster. This data set, obtained with the Arcetri NICMOS3 camera ARNICA mounted on the Gornergrat Infrared Telescope, is aimed at complementing, with observations of mostly early-type objects, our NIR survey of spiral galaxies in these regions, presented in previous papers of this series. Magnitudes at the optical radius, total magnitudes, isophotal radii and light concentration indices are derived. We confirm the existence of a positive correlation between the near-infrared concentration index and the galaxy H-band luminosity Based on observations taken at TIRGO (Gornergrat, Switzerland). TIRGO is operated by CAISMI-CNR, Arcetri, Firenze, Italy. Tables 1 and 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

  14. 1.65?m (H-band) surface photometry of galaxies. II. Observations of 297 galaxies with the TIRGO 1.5m telescope.

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Pierini, D.; Baffa, C.; Lisi, F.; Hunt, L. K.; Randone, I.; Boselli, A.

    1996-12-01

    We present near-infrared H-band (1.65?m) surface photometry of 297 galaxies (mostly) in the Coma Supercluster obtained with the Arcetri NICMOS3 camera, ARNICA, mounted on the Gornergrat Infrared Telescope. Magnitudes and diameters within the 21.5mag/arcsec^2^ isophote, concentration indices, and total H magnitudes are derived. Combining these observations with those obtained similarly using the Calar Alto telescopes (Paper I, 1996A&AS..120..489G) we find a strong positive correlation between the near-infrared concentration index and the galaxy H-band luminosity, and we analyze the consequent dependence of near-infrared growth-curves on H-band luminosity.

  15. Introduction to astronomical photometry

    Microsoft Academic Search

    M. Golay

    1974-01-01

    General definitions and questions of energy distribution for various spectral types are considered along with photometric measurements, effects of bandwidths and interstellar absorption, the two-dimensional photometric representations of stars, multicolor and wideband photometry, intermediate and narrow passband photometry, and photometric parameters and their correlation with basic parameters describing the physical state of stellar atmospheres. Applications of photometry to various stellar

  16. Exploration mode affects visuohaptic integration of surface orientation.

    PubMed

    Plaisier, Myrthe A; van Dam, Loes C J; Glowania, Catharina; Ernst, Marc O

    2014-01-01

    We experience the world mostly in a multisensory fashion using a combination of all of our senses. Depending on the modality we can select different exploration strategies for extracting perceptual information. For instance, using touch we can enclose an object in our hand to explore parts of the object in parallel. Alternatively, we can trace the object with a single finger to explore its parts in a serial fashion. In this study we investigated whether the exploration mode (parallel vs. serial) affects the way sensory signals are combined. To this end, participants visually and haptically explored surfaces that varied in roll angle and indicated which side of the surface was perceived as higher. In Experiment 1, the exploration mode was the same for both modalities (i.e., both parallel or both serial). In Experiment 2, we introduced a difference in exploration mode between the two modalities (visual exploration was parallel while haptic exploration was serial or vice versa). The results showed that visual and haptic signals were combined in a statistically optimal fashion only when the exploration modes were the same. In case of an asymmetry in the exploration modes across modalities, integration was suboptimal. This indicates that spatial-temporal discrepancies in the acquisition of information in the two senses (i.e., haptic and visual) can lead to the breakdown of sensory integration. PMID:25413627

  17. Do surface processes and/or the presence of an initial surface topography affect(s) the fold linkage?

    NASA Astrophysics Data System (ADS)

    Collignon, Marine; Fernandez, Naiara; Kaus, Boris J. P.

    2014-05-01

    Landscape geomorphology provides an indirect observation of the tectonic activity. Surface processes and tectonics interact one with another to create a wide variety of landscape. Geomorphic features such as wind gaps can record the amplification and lateral propagation of embryonic fold segments. Depending of their relative initial spacing, those growing fold segments can link and form long train folds. This mechanism has been suggested for the Zagros Folded Belt, where the axial lengths of folds can reach more than 100 km. Previous studies have focused on fold linkage or on the response of the drainage network to tectonic forcing. Using seeds in their setup to prescribe the fold orientation, Grasemann and Schmalholz (2012) numerically investigated the distance between two isolated laterally propagating folds to explain the different modes of linkage. However, the effects of surface processes on the fold development have not been considered. Our recent multilayer folding experiments, in which an initial random perturbation was prescribed, have shown that under efficient drainage network conditions, or when a non-zero initial topography was applied to the model, the type of fold linkage could be modified. In this study we systematically investigate the effects of surface processes on the mode of linkage and how the distance between two isolated growing perturbations, required for linkage, is affected. In order to address this question, we use the 3D thermo-mechanical code LaMEM, which has been coupled to a finite-element based landscape evolution model (both erosion and sedimentation). The landscape evolution model uses a non-linear diffusion formulation (Simpson and Schlunegger, 2003) taking into account both hillslopes and channel processes. Graseman, B., and Schmalholz, S. M., 2012, Lateral fold growth and fold linkage: Geology, v. 40. Simpson, G., and Schlunegger, F., 2003, Topographic evolution and morphology of surfaces evolving in repsonse to coupled fluvial and hillslope sediment transport: Journal of geophysical research, v. 108, p. 16p.

  18. Deep multiband surface photometry on a sample of 24 blue compact galaxies. II. A volume-limited sample of 21 emission line galaxies

    NASA Astrophysics Data System (ADS)

    Micheva, G.; Östlin, G.; Zackrisson, E.; Bergvall, N.; Marquart, T.; Masegosa, J.; Marquez, I.; Cumming, R. J.; Durret, F.

    2013-08-01

    Aims: We present deep surface photometry of a volume-limited sample of 21 UM emission line galaxies in broadband optical UBVRI and near infrared (NIR) HKs filters. The sample comprises 19 blue compact galaxies (BCGs) and two spirals. Methods: We separated the burst and host populations for each galaxy and compared them to stellar evolutionary models with and without nebular emission contribution. We measured and analyzed the A180 asymmetry in all filters, the concentration index C, the scale length, and the central surface brightness of the host galaxy. Results: A shift in the average A180 asymmetry is detected from optical to NIR. This shift seems correlated with the morphological class of the BCGs. Using the color-asymmetry relation, we identify five BCGs in the sample as mergers, which is confirmed by their morphological class. Though clearly separated from normal galaxies in the concentration-asymmetry parameter space, we find that it is not possible to distinguish luminous starbursting BCGs from the merely star forming low luminosity BCGs. Reduced images (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/556/A10

  19. SURFACE ENERGY BALANCE AFFECTS GAS EXCHANGE OF THREE SHRUB SPECIES

    Microsoft Academic Search

    Thayne Montague; Roger Kjelgren; Larry Rupp

    We investigated the energy balance of vegetative and nonvegetative surfaces and gas exchange for 3 shrub species growing over each surface. During a 1 -week period, incoming short-wave radiation, surface and soil tempera- ture, and soil heat flux for turf and pine-bark mulch surfaces were gathered. Air temperature and relative humidity at 2 heights over each surface were also measured.

  20. Near-infrared and optical broadband surface photometry of 86 face-on disk dominated galaxies. IV. Using color profiles to study stellar and dust content of galaxies

    E-print Network

    Roelof S. de Jong

    1996-04-02

    The stellar and dust content of spiral galaxies as function of radius has been investigated using near-infrared and optical broadband surface photometry of 86 face-on spiral galaxies. Colors of galaxies correlate with the azimuthally averaged local surface brightness both within and among galaxies, with the lower surface brightness regions being bluer. The colors formed from different passband combinations correlate strongly indicating that they probably arise from the same physical process. A 3D radiative transfer model was developed to calculate the effect of dust absorption and scattering on the luminosity and color profiles of galaxies. Stellar synthesis models were used to investigate the effects of the star formation history and the metallicity on the broadband color profiles. Combining all optical and near-infrared data shows that the color gradients in this sample of face-on galaxies are best explained by a combined stellar age and metallicity gradient across the disk, with the outer regions being on average younger and of lower metallicity. Dust reddening probably plays only a minor role, as the dust models cannot produce reddening profiles that are compatible with the observations. The observed color differences implicate substantial M/L_lambda differences, both within galaxies and among galaxies. The variations are such that the ``missing light'' problem derived from rotation fitting becomes even worse. Late-type galaxies (T>=6) have lower metallicities and are often of younger average age than earlier types and have therefore an entirely different M/L_\\lambda in most passbands. The near-infrared passbands are recommended for studies where the M/L_\\lambda ratios should not vary too much.

  1. Boundary Contour Based Surface Integration Affected by Color

    PubMed Central

    Su, Yong R; He, Zijiang J; Ooi, Teng Leng

    2010-01-01

    The visual system represents occluded surfaces by integrating the visible and partially occluded fragments with reliance on surface boundary contours. Does surface integration also depend on color similarity? Using displays with aligned images, we found the visual system has a preference to integrate images with the same color to form occluded surfaces and construct illusory occluding surfaces. This results in enhanced shape discrimination of briefly presented stimuli, and a tendency to perceive global motion of the integrated fragments. The contribution of color to surface integration is observed both in equiluminous setting and in non-equiluminous setting where achromatic contrast exists. PMID:20558193

  2. Colloid Surface Chemistry Critically Affects Multiple Particle Tracking Measurements of Biomaterials

    E-print Network

    Gardel, Margaret

    Colloid Surface Chemistry Critically Affects Multiple Particle Tracking Measurements they probe. We here show that colloid surface chemistry can profoundly affect multiple particle tracking present a simple protocol to render the surface of colloidal probe particles protein-resistant by grafting

  3. The Aerodynamic Characteristics of Airfoils as Affected by Surface Roughness

    NASA Technical Reports Server (NTRS)

    HOCKER RAY W

    1933-01-01

    The effect on airfoil characteristics of surface roughness of varying degrees and types at different locations on an airfoil was investigated at high values of the Reynolds number in a variable density wind tunnel. Tests were made on a number of National Advisory Committee for Aeronautics (NACA) 0012 airfoil models on which the nature of the surface was varied from a rough to a very smooth finish. The effect on the airfoil characteristics of varying the location of a rough area in the region of the leading edge was also investigated. Airfoils with surfaces simulating lap joints were also tested. Measurable adverse effects were found to be caused by small irregularities in airfoil surfaces which might ordinarily be overlooked. The flow is sensitive to small irregularities of approximately 0.0002c in depth near the leading edge. The tests made on the surfaces simulating lap joints indicated that such surfaces cause small adverse effects. Additional data from earlier tests of another symmetrical airfoil are also included to indicate the variation of the maximum lift coefficient with the Reynolds number for an airfoil with a polished surface and with a very rough one.

  4. Stellar photometry - Current techniques and future developments

    NASA Astrophysics Data System (ADS)

    Butler, C. J.; Elliott, I.

    1993-08-01

    Stellar photometry deals with the accurate measurement of light from stars and galaxies. It is one of the principal tools of the astronomer and is used in the determination of the brightness, radius and temperature of stars, and, increasingly, in the study of their atmospheres and interiors. The book contains the proceedings of a colloquium held in Dublin in August 1992 that reviewed the most recent developments in stellar photometry and the many technical problems that face photometrists in their quest for ever more accurate and meaningful data. This book covers the following topics: (1)Photometric systems; including the pros and cons of rival photometric systems and how they are affected by choice of detector and equipment design; (2)High precision photometry; the factors that limit the routine attainment of millimagnitude accuracy both in measurement and conversion to a standard system; (3)New techniques in photometry, using multichannel arrays in the optical and infrared regions; (4)Automatic photoelectric telescopes and the setting up of global networks to provide continuous photometric coverage; (5)Photometry with CCDs, and (6)Photometry from instruments in space or on the Moon.

  5. Plant surface wax affects parasitoid's response to host footprints

    NASA Astrophysics Data System (ADS)

    Rostás, Michael; Ruf, Daniel; Zabka, Vanessa; Hildebrandt, Ulrich

    2008-10-01

    The plant surface is the substrate upon which herbivorous insects and natural enemies meet and thus represents the stage for interactions between the three trophic levels. Plant surfaces are covered by an epicuticular wax layer which is highly variable depending on species, cultivar or plant part. Differences in wax chemistry may modulate ecological interactions. We explored whether caterpillars of Spodoptera frugiperda, when walking over a plant surface, leave a chemical trail (kairomones) that can be detected by the parasitoid Cotesia marginiventris. Chemistry and micromorphology of cuticular waxes of two barley eceriferum wax mutants ( cer-za.126, cer-yp.949) and wild-type cv. Bonus (wt) were assessed. The plants were then used to investigate potential surface effects on the detectability of caterpillar kairomones. Here we provide evidence that C. marginiventris responds to chemical footprints of its host. Parasitoids were able to detect the kairomone on wild-type plants and on both cer mutants but the response to cer-yp.949 (reduced wax, high aldehyde fraction) was less pronounced. Experiments with caterpillar-treated wt and mutant leaves offered simultaneously, confirmed this observation: no difference in wasp response was found when wt was tested against cer-za.126 (reduced wax, wt-like chemical composition) but wt was significantly more attractive than cer-yp.949. This demonstrates for the first time that the wax layer can modulate the detectability of host kairomones.

  6. Free-surface stability criterion as affected by velocity distribution

    USGS Publications Warehouse

    Cheng-Lung, Chen

    1995-01-01

    This paper examines how the velocity distribution of flow in open channels affects the kinematic and dynamic wave velocities, from which the various forms of the Vedernikov number V can be formulated. When V >1, disturbances created in open-channel flow will amplify in the form of roll waves; when V <1, some (though not all) disturbances will attenuate. A study of the Vedernikov stability criterion reveals that it can be readily deduced within the framework of the kinematic and dynamic wave theories by comparing the kinematic wave velocity to the corresponding dynamic wave velocity. -from Author

  7. Human actions affect Greenland Ice Sheet surface mass balance

    NASA Astrophysics Data System (ADS)

    Orwig, Jessica

    2014-12-01

    A new study that combines a model of glacial surface mass balance with a global climate model determines how much of the current and future increase in marginal melting and interior accumulation of the Greenland Ice Sheet is due to human activity rather than natural forces. The Greenland Ice Sheet, the largest continental glacier in the world, is shrinking at an increasing rate, but scientists are unsure how much of this shrinkage is due to natural versus human-driven climate change.

  8. Texture properties affecting the accuracy of surface attitude judgements.

    PubMed

    Velisavljevi?, Ljiljana; Elder, James H

    2006-07-01

    Prior studies of the perception of surface shape and attitude from texture have focused on measuring the sensitivity of the visual system to the various geometric deformations induced by projection. Studies that examine variations in accuracy caused by spatial properties of the texture itself are fewer, and often confound multiple, potentially important properties. Here we examine the perception of surface attitude for a broad range of synthetic textures that may represent the types of structure encountered in the natural world. These stimuli allow us to isolate the respective roles of texels, spatial scale structure, discrete symmetries and regularity in the judgement of both the slant and tilt of textured surfaces. Texels, spatial scale structure and discrete symmetries were all found to play a role. Discrete rotational symmetries were found to be particularly important for accurate tilt estimation, likely mediated by skew symmetry and/or linear perspective cues. The operational range of viewing distances over which accurate attitude judgements can be made is greatly extended when texture structure is distributed over multiple scales. Small biases caused by variations in the spin of symmetric textures are observed and are consistent, at least qualitatively, with a Bayesian cue combination model previously proposed by . PMID:16504236

  9. How strain affects the reactivity of surface metal oxide catalysts.

    PubMed

    Amakawa, Kazuhiko; Sun, Lili; Guo, Chunsheng; Hävecker, Michael; Kube, Pierre; Wachs, Israel E; Lwin, Soe; Frenkel, Anatoly I; Patlolla, Anitha; Hermann, Klaus; Schlögl, Robert; Trunschke, Annette

    2013-12-16

    Highly dispersed molybdenum oxide supported on mesoporous silica SBA-15 has been prepared by anion exchange resulting in a series of catalysts with changing Mo densities (0.2-2.5?Mo atoms?nm(-2) ). X-ray absorption, UV/Vis, Raman, and IR spectroscopy indicate that doubly anchored tetrahedral dioxo MoO4 units are the major surface species at all loadings. Higher reducibility at loadings close to the monolayer measured by temperature-programmed reduction and a steep increase in the catalytic activity observed in metathesis of propene and oxidative dehydrogenation of propane at 8?% of Mo loading are attributed to frustration of Mo oxide surface species and lateral interactions. Based on DFT calculations, NEXAFS spectra at the O-K-edge at high Mo loadings are explained by distorted MoO4 complexes. Limited availability of anchor silanol groups at high loadings forces the MoO4 groups to form more strained configurations. The occurrence of strain is linked to the increase in reactivity. PMID:24259425

  10. THE SL2S GALAXY-SCALE LENS SAMPLE. III. LENS MODELS, SURFACE PHOTOMETRY, AND STELLAR MASSES FOR THE FINAL SAMPLE

    SciTech Connect

    Sonnenfeld, Alessandro; Suyu, Sherry H.; Treu, Tommaso [Physics Department, University of California, Santa Barbara, CA 93106 (United States); Gavazzi, Raphaël [Institut d'Astrophysique de Paris, UMR7095 CNRS-Université Pierre et Marie Curie, 98bis bd Arago, F-75014 Paris (France); Marshall, Philip J., E-mail: sonnen@physics.ucsb.edu [Department of Physics, University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom)

    2013-11-10

    We present Hubble Space Telescope (HST) imaging data and Canada-France-Hawaii Telescope (CFHT) near-infrared ground-based images for the final sample of 56 candidate galaxy-scale lenses uncovered in the CFHT Legacy Survey as part of the Strong Lensing in the Legacy Survey project. The new images are used to perform lens modeling, measure surface photometry, and estimate stellar masses of the deflector early-type galaxies (ETGs). Lens modeling is performed on the HST images (or CFHT when HST is not available) by fitting the spatially extended light distribution of the lensed features assuming a singular isothermal ellipsoid mass profile and by reconstructing the intrinsic source light distribution on a pixelized grid. Based on the analysis of systematic uncertainties and comparison with inference based on different methods, we estimate that our Einstein radii are accurate to ?3%. HST imaging provides a much higher success rate in confirming gravitational lenses and measuring their Einstein radii than CFHT imaging does. Lens modeling with ground-based images, however, when successful, yields Einstein radius measurements that are competitive with space-based images. Information from the lens models is used together with spectroscopic information from companion Paper IV to classify the systems, resulting in a final sample of 39 confirmed (grade A) lenses and 17 promising candidates (grade B,C). This represents an increase of half an order of magnitude in sample size with respect to the sample of confirmed lenses studied in Papers I and II. The Einstein radii of the confirmed lenses in our sample span the range 5-15 kpc and are typically larger than those of other surveys, probing the mass in regions where the dark matter contribution is more important. Stellar masses are in the range 10{sup 11}-10{sup 12} M{sub ?}, covering the range of massive ETGs. The redshifts of the main deflector span a range 0.3 ? z{sub d} ? 0.8, which nicely complements low-redshift samples like the Sloan Lens ACS survey and thus provides an excellent sample for the study of the cosmic evolution of the mass distribution of ETGs over the second half of the history of the universe.

  11. The SL2S Galaxy-scale Lens Sample. III. Lens Models, Surface Photometry, and Stellar Masses for the Final Sample

    NASA Astrophysics Data System (ADS)

    Sonnenfeld, Alessandro; Gavazzi, Raphaël; Suyu, Sherry H.; Treu, Tommaso; Marshall, Philip J.

    2013-11-01

    We present Hubble Space Telescope (HST) imaging data and Canada-France-Hawaii Telescope (CFHT) near-infrared ground-based images for the final sample of 56 candidate galaxy-scale lenses uncovered in the CFHT Legacy Survey as part of the Strong Lensing in the Legacy Survey project. The new images are used to perform lens modeling, measure surface photometry, and estimate stellar masses of the deflector early-type galaxies (ETGs). Lens modeling is performed on the HST images (or CFHT when HST is not available) by fitting the spatially extended light distribution of the lensed features assuming a singular isothermal ellipsoid mass profile and by reconstructing the intrinsic source light distribution on a pixelized grid. Based on the analysis of systematic uncertainties and comparison with inference based on different methods, we estimate that our Einstein radii are accurate to ~3%. HST imaging provides a much higher success rate in confirming gravitational lenses and measuring their Einstein radii than CFHT imaging does. Lens modeling with ground-based images, however, when successful, yields Einstein radius measurements that are competitive with space-based images. Information from the lens models is used together with spectroscopic information from companion Paper IV to classify the systems, resulting in a final sample of 39 confirmed (grade A) lenses and 17 promising candidates (grade B,C). This represents an increase of half an order of magnitude in sample size with respect to the sample of confirmed lenses studied in Papers I and II. The Einstein radii of the confirmed lenses in our sample span the range 5-15 kpc and are typically larger than those of other surveys, probing the mass in regions where the dark matter contribution is more important. Stellar masses are in the range 1011-1012 M ?, covering the range of massive ETGs. The redshifts of the main deflector span a range 0.3 <= zd <= 0.8, which nicely complements low-redshift samples like the Sloan Lens ACS survey and thus provides an excellent sample for the study of the cosmic evolution of the mass distribution of ETGs over the second half of the history of the universe.

  12. Resolution of contamination problems affecting laser surface certification inspection

    NASA Astrophysics Data System (ADS)

    Jackson, L. C.

    1982-03-01

    Contamination from particulate and organic residues which interfered, with the laser surface certification (LSC) inspection of some parts was found to come from three sources: particulate and organic residues from polishing compounds; organic films from cleaning solvents; and particles and organic residues transferred from plastic fixtures used to process these parts. The manufacturing cleaning process was not effective in removing all polishing compound residues, and an extensive cleaning procedure was developed using two solvents in a multicycle ultrasonic/vapor degreasing procedure. Parts were then subjected to gas plasma cleaning which removed the organic films left by the solvent cleaning. Plastic and rubber materials were evaluated for their contamination transfer characteristics; a fluorocarbon elastomer was the least contaminating. Inspection data established the efficacy of the cleaning procedure. After design relaxation, a single stage ultrasonic vapor degreasing process was used to achieve product acceptance.

  13. Factors Affecting Survival of Bacteriophage on Tomato Leaf Surfaces?

    PubMed Central

    Iriarte, F. B.; Balogh, B.; Momol, M. T.; Smith, L. M.; Wilson, M.; Jones, J. B.

    2007-01-01

    The ability of bacteriophage to persist in the phyllosphere for extended periods is limited by many factors, including sunlight irradiation, especially in the UV zone, temperature, desiccation, and exposure to copper bactericides. The effects of these factors on persistence of phage and formulated phage (phage mixed with skim milk) were evaluated. In field studies, copper caused significant phage reduction if applied on the day of phage application but not if applied 4 or 7 days in advance. Sunlight UV was evaluated for detrimental effects on phage survival on tomato foliage in the field. Phage was applied in the early morning, midmorning, early afternoon, and late evening, while UVA plus UVB irradiation and phage populations were monitored. The intensity of UV irradiation positively correlated with phage population decline. The protective formulation reduced the UV effect. In order to demonstrate direct effects of UV, phage suspensions were exposed to UV irradiation and assayed for effectiveness against bacterial spot of tomato. UV significantly reduced phage ability to control bacterial spot. Ambient temperature had a pronounced effect on nonformulated phage but not on formulated phages. The effects of desiccation and fluorescent light illumination on phage were investigated. Desiccation caused a significant but only slight reduction in phage populations after 60 days, whereas fluorescent light eliminated phages within 2 weeks. The protective formulation eliminated the reduction caused by both of these factors. Phage persistence was dramatically affected by UV, while the other factors had less pronounced effects. Formulated phage reduced deleterious effects of the studied environmental factors. PMID:17259361

  14. Photometry of M33

    NASA Astrophysics Data System (ADS)

    Schlingman, W. M.; Massey, P.

    2003-12-01

    We present UBVRI photometry of stars in the nearby Local Group galaxy M33, obtained by imaging with the Kitt Peak 4-m telescope and MOSAIC camera as part of our Local Group Galaxies survey. To obtain this photometry, we have been developing and strengthening routines that can search through images and automatically photometer these stars using point-spread-function fitting. The routines split the image into its corresponding eight CCD chips and then do automated photometry on each chip separately, so that separate color transformations can be applied in a chip-by-chip manner. Our calibration data comes from images obtained on the Lowell 1.1-m Hall telescope on Anderson Mesa, obtained on numerous pristine photometric nights. Once calibrated, our Mosaic photometry values are averaged, and a complete catalogue of positions and photometry (with errors) is obtained. In the end, we have a list of several hundred thousand stars with magnitudes and colors. These data can be used to analyze the stellar populations in M33, one of our closest neighbors. We will briefly describe our procedure, and present the first HR diagrams from our data. This work has been supported by the NSF under grant AST0093060.

  15. Factors affecting the surface shape and removal rate of workpiece in CMP

    NASA Astrophysics Data System (ADS)

    Fan, Quantang; Zhu, Jianqiang; Zhang, Baoan; Shen, Weixing

    2006-02-01

    The factors affecting the removal rate and surface shape in CMP is introduced. The edge effect is a critical problem in CMP process, which behaves on the global planarization of workpiece-pad interface and change on local planarization and results in collapse or rise in workpiece edges. One of the main factors of edge effect is Von Mises stress, which is a composition stress. The main affecting factor of Von Mises is the axial stress component. The factors affecting the material removal rate (MRR) of workpiece surface and surface nonuniformity include shape, material properties and thickness of pad and polishing media. Factors of load and relative velocity in CMP are also discussed.

  16. Does mineral surface area affect chemical weathering rates?

    NASA Astrophysics Data System (ADS)

    Salome Eiriksdottir, Eydis; Reynir Gislason, Sigurdur; Oelkers, Eric H.

    2010-05-01

    Iceland is a basaltic volcanic island representative of the high relief, volcanic and tectonic active islands that contribute over 45% of river suspended material to the oceans worldwide (Milliman and Syvitski, 1992). These islands have enormous mechanical and chemical weathering rates due to the combined effects of high relief, high runoff, the presence of glaciers and easily weathered volcanic rocks, and a lack of sedimentary traps. In total, Iceland delivers 0.7% of the worldwide river suspended matter flux to the ocean, which is approximately one fourth that of Africa (Tómasson, 1990). River suspended matter from volcanic islands is highly reactive in seawater and might play an important role in the global carbon cycle (Gislason et al., 2006). Thus it is important to define and understand the mechanical and chemical weathering rates of these islands. Experimental dissolution experiments performed in the laboratory suggest that chemical weathering rates should be proportional to rock-water interfacial surface area. This hypothesis is tested in the present study through a study of the chemical composition of suspended material collected from rivers located in Northeast Iceland. These rivers were selected for this study because their catchments essentially monolithic, consisting of uniform compositioned and aged basalts. Gaillardet (1999) described weathering intensities of the worlds river systems to be from 1 (low weathering intensity) to 25 (high weathering intensity). These indexes were calculated to be from 1.8 to 3.2 in rivers in NE-Iceland (Eiriksdottir et al., 2008). The surface area of sediments is inversely proportional to particle size; smaller particles have larger specific surface areas. As a result, smaller particles should weather faster. This trend is confirmed by the measured compositions of analyzed suspended material. The concentration of insoluble elements (Zr, Fe, Cu, Ni, Y) is found to increase in the suspended material, whereas the concentration of soluble elements (Na, Ca, Ba, V) decrease with decreasing particle size in samples collected from various catchments. References. Eiriksdottir E.S., Louvat P., Gislason S.R., Óskarsson N., Hardardóttir J., 2008. Temporal variation of chemical and mechanical weathering in NE Iceland: Evaluation of a steady-state model of erosion. EPSL 272, 78-88 Gaillardet, J., Dupré, B., Allegre, C.J., Négrel, P., 1999b. Geochemistry of large river suspended sediments: silicate weathering or recycling tracer? Geochim. Cosmochim. Acta 63, 4037-4051. Gislason, S.R., Oelkers, E.H., Snorrason, Á., 2006. Role of river-suspended material in the global carbon cycle. Geology 34, 49-52. Milliman, J.D., Syvitski, J.P.M., 1992. Geomorphic/tectonic control of sediment discharge to the ocean: the importance of small mountainous rivers. J. Geol. 100, 525-544. Tómasson, H., 1990. Suspended material in Icelandic rivers. In: Guttormur, S. (Ed.), Vatnid og Landid. Orkustofnun, Reykjavik, pp. 169-174.

  17. Galileo photometry of Asteroid 951 Gaspra

    Microsoft Academic Search

    P. Helfenstein; J. Veverka; P. C. Thomas; D. P. Simonelli; P. Lee; K. Klaasen; T. V. Johnson; H. Breneman; J. W. Head; S. Murchie

    1994-01-01

    The mean photometric properties of Gaspra's surface are derived in terms of Hapke's photometric model by combining earth-based telescopic photometry with Galileo's whole-disk and disk-resolved data. The results are used to estimate fundamental properties, such as the geometric albedo, and to compare surface materials on Gaspra with materials on other planetary surfaces. The photometric parameters and a new shape model

  18. APT: Aperture Photometry Tool

    NASA Astrophysics Data System (ADS)

    Laher, Russ

    2012-08-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It has a graphical user interface (GUI) which allows the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. Mouse-clicking on a source in the displayed image draws a circular or elliptical aperture and sky annulus around the source and computes the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs, including image histogram, and aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has functions for customizing calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source model, accessed via the radial-profile-plot panel, allows recovery of source intensity from pixels with missing data and can be especially beneficial in crowded fields.

  19. Neck Muscle Paths and Moment Arms are Significantly Affected by Wrapping Surface Parameters

    E-print Network

    Krishnamoorthy, Bala

    Neck Muscle Paths and Moment Arms are Significantly Affected by Wrapping Surface Parameters.S.A. *Corresponding author. Email: vasavada@wsu.edu We have studied the effects of wrapping surfaces on muscle paths and moment arms of the semispinalis capitis muscle, one of the major extensors of the neck. Sensitivities

  20. How surface roughness affects the angular dependence of the sputtering yield , A. Hassanein

    E-print Network

    Harilal, S. S.

    How surface roughness affects the angular dependence of the sputtering yield A. Hu , A. Hassanein roughness on the angular dependence of sputtering yield. Instead of assuming surfaces to be flat or composed successfully sim- ulated the angular dependence of sputtering yield for various ion-target combinations

  1. The report on performance of image intensifier affected by gas on surface

    NASA Astrophysics Data System (ADS)

    Yan, Lei; Shi, Feng; Cheng, Yaojin; Cheng, Hongchang; Shi, Hongli; Hou, Zhipeng; Liu, Feng

    2011-08-01

    In order to illustrate the performance of intensifier affected by gas on surface, the kovar ring surface has been tested by XPS. According the result, gas type and quantity are calculated. With the theory of thermal and electron stimulated gas desorption, the remaining gas on surface after thermal and electron treatment is reckoned and the surface outgassing rate is evaluated on the assumption that the image intensifier is working in the 10-3lx environment. Then, the performance of image intensifier is evaluated by the effect of gas on the surface at last.

  2. Gaia broad band photometry

    NASA Astrophysics Data System (ADS)

    Jordi, C.; Gebran, M.; Carrasco, J. M.; de Bruijne, J.; Voss, H.; Fabricius, C.; Knude, J.; Vallenari, A.; Kohley, R.; Mora, A.

    2010-11-01

    Aims: The scientific community needs to be prepared to analyse the data from Gaia, one of the most ambitious ESA space missions, which is to be launched in 2012. The purpose of this paper is to provide data and tools to predict how Gaia photometry is expected to be. To do so, we provide relationships among colours involving Gaia magnitudes (white light G, blue GBP, red GRP and GRVS bands) and colours from other commonly used photometric systems (Johnson-Cousins, Sloan Digital Sky Survey, Hipparcos and Tycho). Methods: The most up-to-date information from industrial partners has been used to define the nominal passbands, and based on the BaSeL3.1 stellar spectral energy distribution library, relationships were obtained for stars with different reddening values, ranges of temperatures, surface gravities and metallicities. Results: The transformations involving Gaia and Johnson-Cousins V - IC and Sloan DSS g - z colours have the lowest residuals. A polynomial expression for the relation between the effective temperature and the colour GBP - GRP was derived for stars with Teff ? 4500 K. For stars with Teff < 4500 K, dispersions exist in gravity and metallicity for each absorption value in g - r and r - i. Transformations involving two Johnson or two Sloan DSS colours yield lower residuals than using only one colour. We also computed several ratios of total-to-selective absorption including absorption AG in the G band and colour excess E(GBP - GRP) for our sample stars. A relationship involving AG/AV and the intrinsic (V - IC) colour is provided. The derived Gaia passbands have been used to compute tracks and isochrones using the Padova and BASTI models. Finally, the performances of the predicted Gaia magnitudes have been estimated according to the magnitude and the celestial coordinates of the star. Conclusions: The provided dependencies among colours can be used for planning scientific exploitation of Gaia data, performing simulations of the Gaia-like sky, planning ground-based complementary observations and for building catalogues with auxiliary data for the Gaia data processing and validation. Tables 11-13 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/523/A48

  3. Aperture Photometry Tool

    NASA Astrophysics Data System (ADS)

    Laher, Russ R.; Gorjian, Varoujan; Rebull, Luisa M.; Masci, Frank J.; Fowler, John W.; Helou, George; Kulkarni, Shrinivas R.; Law, Nicholas M.

    2012-07-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It is a graphical user interface (GUI) designed to allow the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. The finely tuned layout of the GUI, along with judicious use of color-coding and alerting, is intended to give maximal user utility and convenience. Simply mouse-clicking on a source in the displayed image will instantly draw a circular or elliptical aperture and sky annulus around the source and will compute the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs with just the push of a button, including image histogram, x and y aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has many functions for customizing the calculations, including outlier rejection, pixel ""picking"" and ""zapping,"" and a selection of source and sky models. The radial-profile-interpolation source model, which is accessed via the radial-profile-plot panel, allows recovery of source intensity from pixels with missing data and can be especially beneficial in crowded fields.

  4. Friction, Wear, and Surface Damage of Metals as Affected by Solid Surface Films

    NASA Technical Reports Server (NTRS)

    Bisson, Edmond E; Johnson, Robert L; Swikert, Max A; Godfrey, Douglas

    1956-01-01

    As predicted by friction theory, experiments showed that friction and surface damage of metals can be reduced by solid surface films. The ability of materials to form surface films that prevent welding was a very important factor in wear of dry and boundary lubricated surfaces. Films of graphitic carbon on cast irons, nio on nickel alloys, and feo and fe sub 3 o sub 4 on ferrous materials were found to be beneficial. Abrasive films such as fe sub 2 o sub 3 or moo sub 3 were definitely detrimental. It appears that the importance of oxide films to friction and wear processes has not been fully appreciated.

  5. Third Workshop on Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J. (Editor); Lasher, Lawrence E. (Editor)

    2001-01-01

    The discoveries of extrasolar planets by Wolszczan, Mayor and Queloz, Butler et al., and others have stimulated a widespread effort to obtain a body of data sufficient to understand their occurrence and characteristics. Doppler velocity techniques have found dozens of extrasolar planets with masses similar to that of Jupiter. Approximately ten percent of the stars that show planets with orbital periods of a few days to a week are expected to show transits. With the mass obtained from Doppler velocity measurements and the size from transit photometry, the densities of the planets can be determined. Theoretical models of the structure of "hot Jupiters" (i.e., those planets within a tenth of an astronomical unit (AU) of the parent star) indicate that these planets should be substantially larger in size and lower in density than Jupiter. Thus the combination of transit and Doppler velocity measurements provide a critical test of the theories of planetary structure. Furthermore, because photometry can be done with small-aperture telescopes rather than requiring the use of much larger telescopes, transit photometry should also reduce the cost of discovering extrasolar planets.

  6. What's Next in Asteroid Photometry

    NASA Astrophysics Data System (ADS)

    Vander Haagen, Gary A.

    2009-05-01

    Our knowledge of an asteroid starts with determination of its position over time using astrometry, calculation of orbital parameters, and collection of time-series photometry data to reveal its lightcurve, rotational period, and amplitude. Selectively, radar studies are performed by Arecibo and Goldstone to obtain orbital, size, shape, and surface data. Further insight into asteroid populations, general taxonomic class, albedos, estimated diameters and shape require knowledge of their absolute magnitude (H) and phase slope parameter (G) values. The H-G values are determined through reduced photometric data as the asteroid passes through its opposition or 0° phase angle. Collection of these data is ideally suited to smaller observatories since the time required is considerable and therefore costly for larger facilities. The H-G parameters were determined for 901 Brunsia and 946 Poesia thereby yielding new insight into their absolute magnitudes, albedos, diameter, and general taxonomic classification.

  7. THE IMPACT OF CONTAMINATED RR LYRAE/GLOBULAR CLUSTER PHOTOMETRY ON THE DISTANCE SCALE

    SciTech Connect

    Majaess, D.; Turner, D.; Lane, D. [Department of Astronomy and Physics, Saint Mary's University, Halifax, NS B3H 3C3 (Canada); Gieren, W., E-mail: dmajaess@ap.smu.ca [Departamento de Astronomia, Universidad de Concepcion, Casilla 160-C, CL Concepcion (Chile)

    2012-06-10

    RR Lyrae variables and the stellar constituents of globular clusters are employed to establish the cosmic distance scale and age of the universe. However, photometry for RR Lyrae variables in the globular clusters M3, M15, M54, M92, NGC 2419, and NGC 6441 exhibit a dependence on the clustercentric distance. For example, variables and stars positioned near the crowded high-surface brightness cores of the clusters may suffer from photometric contamination, which invariably affects a suite of inferred parameters (e.g., distance, color excess, absolute magnitude, etc.). The impetus for this study is to mitigate the propagation of systematic uncertainties by increasing awareness of the pernicious impact of contaminated and radial-dependent photometry.

  8. Nutrient losses in runoff from feedlot surfaces as affected by unconsolidated surface materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Beef cattle feedlots contain unconsolidated surface materials (USM) (loose manure pack) that accumulate within feedlot pens during a feeding cycle. The effects of varying amounts of USM on feedlot runoff water quality are not well defined. The objectives of this field investigation were to: a) compa...

  9. How impregnation with boron compounds affects the surface hardness of some varnishes

    Microsoft Academic Search

    M. Atar; H. Keskin; S. Korkut; D. S. Korkut

    2011-01-01

    Purpose – The purpose of this paper is to investigate how impregnation with boron compounds affects the surface hardness of varnished wood materials. Design\\/methodology\\/approach – Test samples were prepared from Scotch pine, Oriental spruce, and Uludag fir, which met the requirements of ASTM D 358.These samples were impregnated with boric acid (Ba) and borax (Bx) using a vacuum technique, according

  10. Study of Factors Affecting the Surface Quality in Ultra-Precision Diamond Turning

    Microsoft Academic Search

    C. F. Cheung; W. B. Lee

    2000-01-01

    This paper deals with an investigation of the process factors and the material factors affecting the surface roughness in ultra-precision diamond turning. The process factors involve cutting conditions, tool geometry, and relative tool-work vibration which are related to the cutting geometry and the dynamic characteristics of the cutting process. The material factors considered are material anisotropy, swelling, and crystallographic orientation

  11. Automatic mapping of surfaces affected by forest fires in Spain using AVHRR NDVI composite image data

    Microsoft Academic Search

    Alberto Fernández; Pilar Illera; Jose Luis Casanova

    1997-01-01

    In this work, we describe the statistical techniques used to analyze images from the National Oceanic and Atmospheric Administration's advanced very high resolution radiometer for the calculation and mapping of surfaces affected by large forest fires in Spain in 1993 and 1994. Maximum value normalized difference vegetation index (NDVI) composites (MVCs) were generated for every ten-day period over the two

  12. Factors affecting surface quality in diamond turning of oxygen-free high-conductance copper.

    PubMed

    Zhang, H; Zhang, X

    1994-04-01

    In identical cutting conditions, it has been shown that the surface quality of ultraprecisely machined oxygen-free high-conductance copper samples, for which a single-point diamond tool is used, depends on the microstructure and properties of the materials, as well as the processing sequence. It has been found that samples subjected to colddeformation-recrystallization annealing have the best surface quality after being diamond turned. In addition, crystal uniformity and the processing sequence affect the roughness and residual stress of the finished surface. PMID:20885541

  13. Exoplanets photometry with remote observatory

    NASA Astrophysics Data System (ADS)

    Vanhuysse, M.; Cales, J.-P.; Technologie, C.; Santerne, A.; Moutou, C.

    2011-10-01

    As radial velocity data, photometry is very important in order to characterize an exoplanet. Photometry of long orbital period transiting exoplanet ,such as those discovered by space-based photometry (CoRoT, Kepler) or from radial velocity are difficult to obtain from the ground. Larger professional telescope cost a lot and generally are busy for observing in photometry for a large amount of nights. We are following up transiting exoplanets with the Oversky remote observatory, which is dedicate to exoplanet photometry and located at La Palma Island (canary), and tele-operate from France via internet. One year after the installation, we reach professionals precisions that permit us to start collaboration with professionals' astronomers. We will present our remote observatory as well as we will highlight our results and compare them with professional telescope accuracy.

  14. Automatic Mapping of Surfaces Affected by Forest Fires in Spain Using AVHRR NDVI Composite Image Data

    Microsoft Academic Search

    Alberto Ferndndez; Pilar Illera; Jose Luis Casanova

    In this work, we describe the statistical techniques used to analyze images from the National Oceanic and Atmo- spheric Administration's' advanced ver~j high resolution radiometer for the calculation and mapping of surfaces affected by large fi)restfires in Spain in 1993 and 1994. Maximum value normalized difference vegetation index (NDVI) composites (MVCs) were generated for every ten-day period over the two

  15. BVR photometry of a newly identified RS CVn binary star HD 61396

    E-print Network

    Sudhanshu Barway; S. K. Pandey; Padmakar Singh Parihar

    2004-08-10

    BVR photometry of a recently identified RS CVn binary star HD61396, carried out during 2001, is presented. The new photometry reveal significant evolution in the shape and amplitude of light curve when compared with those reported earlier by Padmakar etal (2000). The traditional two-starspot model has been used to obtain the spot parameters from the observed light curve. Changes in the spot area and their location on the stellar surface are discernible from the extracted parameters from the new photometry.

  16. Introduction Observations PSF fitting Photometry Results Defocused PSF-fitting Photometry

    E-print Network

    Pinfield, David J.

    Introduction Observations PSF fitting Photometry Results Defocused PSF-fitting Photometry Ro Parviainen Defocused PSF-fitting Photometry #12;Introduction Observations PSF fitting Photometry Results 1 Introduction The light curve Defocused PSF 2 Observations Observations 3 PSF fitting Photometry PSF model 1 PSF

  17. Precision photometry for planetary transits

    E-print Network

    Frederic Pont; Claire Moutou

    2007-02-06

    We review the state of the art in follow-up photometry for planetary transit searches. Three topics are discussed: (1) Photometric monitoring of planets discovered by radial velocity to detect possible transits (2) Follow-up photometry of candidates from photometric transit searches to weed out eclipsing binaries and false positives (3) High-precision lightcurves of known transiting planets to increase the accuracy on the planet parameters.

  18. How will surface treatments affect the translucency of porcelain laminate veneers?

    PubMed Central

    Turgut, Sedanur; Ayaz, Elif Aydogan; Korkmaz, Fatih Mehmet; Ulusoy, K?vanç Utku; Bagis, Yildirim Hakan

    2014-01-01

    PURPOSE The purpose of this study was to evaluate whether surface treatments affect the translucency of laminate veneers with different shades and thicknesses. MATERIALS AND METHODS A total of 224 disc-shaped ceramic veneers were prepared from A1, A3, HT (High Translucent) and HO (High Opaque) shades of IPS e.max Press (Ivoclar Vivadent) with 0.5 mm and 1.0 mm thicknesses. The ceramics were divided into four groups for surface treatments. Group C: no surface treatments; Group HF: etched with hydrofluoric acid; Group SB: sandblasted with 50-µm Al2O3; and Group L; irradiated with an Er;YAG laser. A translucent shade of resin cement (Rely X Veneer, 3M ESPE) was chosen for cementation. The color values of the veneers were measured with a colorimeter and translucency parameter (TP) values were calculated. A three-way ANOVA with interactions for TP values was performed and Bonferroni tests were used when appropriate (?=0.05). RESULTS There were significant interactions between the surface treatments, ceramic shades and thicknesses (P=.001). For the 0.5-mm-thick specimens there were significant differences after the SB and L treatments. There was no significant difference between the HF and C treatments for any shades or thicknesses (P>.05). For the 1-mm-thick ceramics, there was only a significant difference between the L and C treatments for the HT shade ceramics (P=.01). There were also significant differences between the SB and C treatments except not for the HO shades (P=.768). CONCLUSION The SB and L treatments caused laminate veneers to become more opaque; however, HF treatment did not affect the TP values. When the laminate veneers were thinner, both the shade of the ceramic and the SB and laser treatments had a greater effect on the TP values. PMID:24605200

  19. Comparison of aerosol optical depth inferred from surface measurements with that determined by Sun photometry for cloud-free conditions at a continental U.S. site

    Microsoft Academic Search

    M. H. Bergin; S. E. Schwartz; R. N. Halthore; J. A. Ogren; D. L. Hlavka

    2000-01-01

    Evaluation of the forcing of climate by aerosol scattering of shortwave radiation in cloud-free conditions (direct aerosol forcing) requires knowledge of aerosol optical properties on relevant spatial and temporal scales. It is convenient to measure these properties at the surface. However, before these measurements can be used to quantitatively estimate direct climate forcing, it is necessary to determine the extent

  20. Seat surface inclination may affect postural stability during Boccia ball throwing in children with cerebral palsy.

    PubMed

    Tsai, Yung-Shen; Yu, Yi-Chen; Huang, Po-Chang; Cheng, Hsin-Yi Kathy

    2014-12-01

    The aim of the study was to examine how seat surface inclination affects Boccia ball throwing movement and postural stability among children with cerebral palsy (CP). Twelve children with bilateral spastic CP (3 with gross motor function classification system Level I, 5 with Level II, and 4 with Level III) participated in this study. All participants underwent pediatric reach tests and ball throwing performance analyses while seated on 15° anterior- or posterior-inclined, and horizontal surfaces. An electromagnetic motion analysis system was synchronized with a force plate to assess throwing motion and postural stability. The results of the pediatric reach test (p = 0.026), the amplitude of elbow movement (p = 0.036), peak vertical ground reaction force (PVGRF) (p < 0.001), and movement range of the center of pressure (COP) (p < 0.020) were significantly affected by seat inclination during throwing. Post hoc comparisons showed that anterior inclination allowed greater amplitude of elbow movement and PVGRF, and less COP movement range compared with the other inclines. Posterior inclination yielded less reaching distance and PVGRF, and greater COP movement range compared with the other inclines. The anterior-inclined seat yielded superior postural stability for throwing Boccia balls among children with bilateral spastic CP, whereas the posterior-inclined seat caused difficulty. PMID:25241116

  1. Osteoclasts but not osteoblasts are affected by a calcified surface treated with zoledronic acid in vitro

    SciTech Connect

    Schindeler, Aaron [Department of Orthopaedic Research and Biotechnology, Children's Hospital at Westmead, Sydney (Australia) and Discipline of Paediatrics and Child Health, Faculty of Medicine, University of Sydney, Sydney (Australia)]. E-mail: AaronS@chw.edu.au; Little, David G. [Department of Orthopaedic Research and Biotechnology, Children's Hospital at Westmead, Sydney (Australia); Discipline of Paediatrics and Child Health, Faculty of Medicine, University of Sydney, Sydney (Australia)

    2005-12-16

    Bisphosphonates are potent inhibitors of osteoclast-mediated bone resorption. Recent interest has centered on the effects of bisphosphonates on osteoblasts. Chronic dosing of osteoblasts with solubilized bisphosphonates has been reported to enhance osteogenesis and mineralization in vitro. However, this methodology poorly reflects the in vivo situation, where free bisphosphonate becomes rapidly bound to mineralized bone surfaces. To establish a more clinically relevant cell culture model, we cultured bone cells on calcium phosphate coated quartz discs pre-treated with the potent nitrogen-containing bisphosphonate, zoledronic acid (ZA). Binding studies utilizing [{sup 14}C]-labeled ZA confirmed that the bisphosphonate bound in a concentration-dependent manner over the 1-50 {mu}M dose range. When grown on ZA-treated discs, the viability of bone-marrow derived osteoclasts was greatly reduced, while the viability and mineralization of the osteoblastic MC3T3-E1 cell line were largely unaffected. This suggests that only bone resorbing cells are affected by bound bisphosphonate. However, this system does not account for transient exposure to unbound bisphosphonate in the hours following a clinical dosing. To model this event, we transiently treated osteoblasts with ZA in the absence of a calcified surface. Osteoblasts proved highly resistant to all transitory treatment regimes, even when utilizing ZA concentrations that prevented mineralization and/or induced cell death when dosed chronically. This study represents a pharmacologically more relevant approach to modeling bisphosphonate treatment on cultured bone cells and implies that bisphosphonate therapies may not directly affect osteoblasts at bone surfaces.

  2. Photometric Redshifts and Photometry Errors

    E-print Network

    D. Wittman; P. Riechers; V. E. Margoniner

    2007-09-21

    We examine the impact of non-Gaussian photometry errors on photometric redshift performance. We find that they greatly increase the scatter, but this can be mitigated to some extent by incorporating the correct noise model into the photometric redshift estimation process. However, the remaining scatter is still equivalent to that of a much shallower survey with Gaussian photometry errors. We also estimate the impact of non-Gaussian errors on the spectroscopic sample size required to verify the photometric redshift rms scatter to a given precision. Even with Gaussian {\\it photometry} errors, photometric redshift errors are sufficiently non-Gaussian to require an order of magnitude larger sample than simple Gaussian statistics would indicate. The requirements increase from this baseline if non-Gaussian photometry errors are included. Again the impact can be mitigated by incorporating the correct noise model, but only to the equivalent of a survey with much larger Gaussian photometry errors. However, these requirements may well be overestimates because they are based on a need to know the rms, which is particularly sensitive to tails. Other parametrizations of the distribution may require smaller samples.

  3. Nature of immobilization surface affects antibody specificity to placental alkaline phosphatase.

    PubMed

    Kumar, Mukesh; Khan, Imran; Sinha, Subrata

    2015-01-01

    Retention of native conformation of immobilized protein is essential for various applications including selection and detection of specific recombinant antibodies (scFvs). Placental alkaline phosphatase (PAP), an onco-fetal antigen expressed on the surface of several tumors, was immobilized on supermagnetic particles for selection of recombinant antibodies from a human phage display antibody library. The isolated antibodies were found to be cross-reactive to either of the isozymes of alkaline phosphatase, i.e., bone alkaline phosphatase (BAP) or intestinal alkaline phosphatase (IAP) and could not be used for tumor targeting. A specific anti-PAP monoclonal antibody H17E2 was tested for retention of specificity under these conditions. Binding of the antibody to magnetic beads conjugated IAP and BAP along with PAP and the ability of the two isozymes to inhibit its binding to PAP depicted the loss of isozyme specificity of the antibody. However, the antibody retained its specificity to PAP immobilized on polyvinyl chloride (PVC) surface. Enzyme activity was observed on both surfaces. This demonstrates that nature of immobilization may affect antigen-antibody binding in subtle ways, resulting in alteration of conformation of the epitopes. This may have consequences for determining the specificity of antibody binding for proteins that share a high degree of homology. PMID:25321174

  4. Biofilm Formation by the Fish Pathogen Flavobacterium columnare: Development and Parameters Affecting Surface Attachment

    PubMed Central

    Cai, Wenlong; De La Fuente, Leonardo

    2013-01-01

    Flavobacterium columnare is a bacterial fish pathogen that affects many freshwater species worldwide. The natural reservoir of this pathogen is unknown, but its resilience in closed aquaculture systems posits biofilm as the source of contagion for farmed fish. The objectives of this study were (i) to characterize the dynamics of biofilm formation and morphology under static and flow conditions and (ii) to evaluate the effects of temperature, pH, salinity, hardness, and carbohydrates on biofilm formation. Nineteen F. columnare strains, including representatives of all of the defined genetic groups (genomovars), were compared in this study. The structure of biofilm was characterized by light microscopy, confocal laser scanning microscopy, and scanning electron microscopy. F. columnare was able to attach to and colonize inert surfaces by producing biofilm. Surface colonization started within 6 h postinoculation, and microcolonies were observed within 24 h. Extracellular polysaccharide substances and water channels were observed in mature biofilms (24 to 48 h). A similar time course was observed when F. columnare formed biofilm in microfluidic chambers under flow conditions. The virulence potential of biofilm was confirmed by cutaneous inoculation of channel catfish fingerlings with mature biofilm. Several physicochemical parameters modulate attachment to surfaces, with the largest influence being exerted by hardness, salinity, and the presence of mannose. Maintenance of hardness and salinity values within certain ranges could prevent biofilm formation by F. columnare in aquaculture systems. PMID:23851087

  5. Properties of Young Massive Cluster Derived from Photometry

    E-print Network

    U. Fritze-v. Alvensleben

    2004-08-25

    I will show that photometry -- if extending over a reasonable choice of passbands -- can give fairly precise information about young star clusters and their evolutionary state. Optical colors alone are known to leave severe ambiguities due to degeneracies between age, metallicity and extinction. High quality photometry including $U, B, V$ or $I$, and a NIR band, however, in combination with an extensive grid of evolutionary synthesis models for star clusters and a dedicated tool to analyse spectral energy distributions allows to assess and largely disentangle star cluster ages, metallicities, extinction values and, hence, to derive their masses. Gaseous emission contributions sensibly affect broad band colors during the youngest stages, depending on metallicity. Mass functions of young star cluster systems may considerably differ in shape from luminosity functions. An ESO ASTROVIRTEL project provides multi-color photometry for a large number of young, intermediate age and old star cluster systems. As a first example I show results obtained for NGC 1569.

  6. Detection by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J.; Koch, David G.; Jenkins, Jon M.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    A periodic sequence of planetary transits provides a valid detection of an orbiting planet and provides the relative size of the planet and its orbital period. Ancillary measurements of the stellar spectrum and the variations of the star's radial velocity or position combined with stellar models allow the absolute size of the planet and its mass to be obtained. The results of this approach have already shown that the planet orbiting HD209458 has only 70% of the mass of Jupiter, but is nearly 50% larger in radius. Based on models of planetary structure, these results imply that the planet must have spent most of its lifetime so close to the star that it has not been able to cool and contract as have the giant planets in our Solar System. Thus its density is much less than Jupiter and Saturn and is actually less than that of water; i.e., about 0.4 gr/cu cm. If more sensitive measurements of the light curve of stars with closely orbiting planets can be made that provide the varying amplitude of the light reflected by the planet at various phases in its orbit, then characteristics of the planetary atmosphere can be obtained. Potentially, these data can identify major molecular species present in the atmosphere and tell us if clouds are present and yield the phase function of the aerosols. Although such detail cannot be obtained for Earth-size planets because their signal amplitudes are too small, it is possible to get data critical to the determination of the structure of extrasolar planetary systems. In particular, the size distributions and their orbital distributions can be measured by the transit photometry missions now in development. The COROT mission should be able to find large terrestrial planets in short-period orbits while the more ambitious Kepler and Eddington missions should be able to detect planets even smaller than the Earth and at orbital distances that place them in the habitable zone of their stars.

  7. Soil factors affecting mycorrhizal use in surface mine reclamation. Information circular/1993

    SciTech Connect

    Norland, M.R.

    1993-01-01

    Surface and subsurface stabilization of mining-related wastes through revegetation depends upon the physical, chemical, and biological condition of the waste following mining. Mining disturbances can significantly alter the soil physical, chemical, and biological characteristics of a site, reducing or eliminating mycorrhizal fungi from the soil. Mycorrhizae are economically and ecologically important because they can alleviate environmental stresses caused by lack of proper soil condition and because they are vital to stabilization of mining waste by increasing plant survival and biomass through increased nutrient and water uptake. The report discusses some of the ecological factors that may affect mycorrhizae-plant associations on mining-related wastes and provides general information on mycorrhizae inoculation technology.

  8. Mendelian and non-mendelian mutations affecting surface antigen expression in Paramecium tetraurelia.

    PubMed Central

    Epstein, L M; Forney, J D

    1984-01-01

    A screening procedure was devised for the isolation of X-ray-induced mutations affecting the expression of the A immobilization antigen (i-antigen) in Paramecium tetraurelia. Two of the mutations isolated by this procedure proved to be in modifier genes. The two genes are unlinked to each other and unlinked to the structural A i-antigen gene. These are the first modifier genes identified in a Paramecium sp. that affect surface antigen expression. Another mutation was found to be a deletion of sequences just downstream from the A i-antigen gene. In cells carrying this mutation, the A i-antigen gene lies in close proximity to the end of a macronuclear chromosome. The expression of the A i-antigen is not affected in these cells, demonstrating that downstream sequences are not important for the regulation and expression of the A i-antigen gene. A stable cell line was also recovered which shows non-Mendelian inheritance of a macronuclear deletion of the A i-antigen gene. This mutant does not contain the gene in its macronucleus, but contains a complete copy of the gene in its micronucleus. In the cytoplasm of wild-type animals, the micronuclear gene is included in the developing macronucleus; in the cytoplasm of the mutant, the incorporation of the A i-antigen gene into the macronucleus is inhibited. This is the first evidence that a mechanism is available in ciliates to control the expression of a gene by regulating its incorporation into developing macronuclei. Images PMID:6092921

  9. Second Workshop on Improvements to Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William J. (editor)

    1988-01-01

    The papers in these proceedings show that a major effort is under way to improve all aspects of photometry. Astronomical multichannel photometry, photodiodes, analog-to-digital converters, data reduction techniques, interference filters and optical fibers are discussed.

  10. Factors affecting the stimulus artifact tail in surface-recorded somatosensory-evoked potentials.

    PubMed

    Hua, Y; Lovely, D F; Doraiswami, R

    2006-03-01

    Surface-recorded somatosensory-evoked potentials (SEPs) are neural signals elicited by an external stimulus. In the case of electrically induced SEPs, the artifact generated by the stimulation process can severely distort the signal. In some cases, the artifact tail often lasts well into the initiation of the SEP making the determination of absolute latency very difficult. In this work, a new approach was taken to identify factors that affect the tail of the artifact. The methodology adopted was the development of a lumped electrical circuit model of the artifact generation process. While the modeling of the instrumentation hardware is relatively simple, this is not the case with tissue and electrode/skin interface effects. Consequently, this paper describes a novel tissue modeling approach that uses an autoregressive moving average (ARMA) parametric technique and an artificial neural network (ANN) to estimate tissue parameters from experimental data. This coupled with an estimation of the stimulation electrode-skin impedance completes the lumped circuit model. Simulink (The Mathworks Inc.) was used to evaluate the model under several different conditions. These results show that both the stimulation electrode-skin interface impedance and nature of the body tissue directly under the recording electrodes have a profound effect on the appearance of the stimulus artifact tail. This was verified by experimentally recorded data obtained from the median nerve using surface electrodes. Conclusions drawn from this work include that stimulation electrodes with low series capacitance should be used whenever possible to minimize the duration of the artifact tail. PMID:16937164

  11. NAAP Variable Star Photometry 1/12 Variable Star Photometry Student Guide

    E-print Network

    Farritor, Shane

    Name: NAAP ­ Variable Star Photometry 1/12 Variable Star Photometry ­ Student Guide Background) ___________________________________________________________________________ #12;Name: NAAP ­ Variable Star Photometry 2/12 Question 3: A CCD has a greatest possible pixel value. This process of alignment is known as registration. #12;Name: NAAP ­ Variable Star Photometry 3

  12. TCP'S USER MANUAL REAL TIME PHOTOMETRY (RTP)

    E-print Network

    TCP'S USER MANUAL REAL TIME PHOTOMETRY (RTP) Last modified: 2011-09-20 This version by: Jorge manual ­ Real Time Photometry (RTP) 20/09/2011 2 1. INTRODUCTION CCD images normally require a lot of calibration work to be rendered useful for high precision photometry. It is therefore not unusual to spend

  13. Photometry of 40 LMC Cepheids

    E-print Network

    N. R. Tanvir; A. Boyle

    1999-07-01

    We present V and I_c CCD photometry for 40 LMC Cepheids at 1 to 3 epochs. This represents a significant increase in the number of LMC Cepheids with $I$-band data, and, as we show, is a useful addition to the sample which can be used to calibrate the period--luminosity relations in these important bands.

  14. HD 52452: New BVRI Photometry

    E-print Network

    Sudhanshu Barway; S. K. Pandey

    2004-08-19

    In this paper we report the multi-band BVRI photometry of HD 52452. The comparison of our data with previous observations reported by Messina et al. (2001) shows that there is a variation in amplitude, but the phases of the two minima, thus the positions of the spot, are quite stable during our observations.

  15. CCD photometry of 625 Xenia

    NASA Astrophysics Data System (ADS)

    Worman, W. E.; Fieber, Sherry; Creason, Mary A.

    615 Xenia was observed for eight nights using CCD photometry during the months of April and May 1998. The period of rotation was 21.101 ± 0.032 hours, and the lightcurve had amplitude of 0.50 ± 0.05 magnitude.

  16. Affine Structure and Photometry

    Microsoft Academic Search

    Ruth Rosenholtz; Jan J. Koenderink

    1996-01-01

    Motion of an observer relative to objects in a scene provides information about the structure of the scene. Changing patterns of shading due to motion relative to the light source provide information about surface structure, albedos, and light sources. One can stratify this photometric information into affine, unitary, and metric structure, much like the stratification of structure from motion. For

  17. Sorption processes affecting arsenic solubility in oxidized surface sediments from Tulare Lake Bed, California

    USGS Publications Warehouse

    Gao, S.; Goldberg, S.; Herbel, M.J.; Chalmers, A.T.; Fujii, R.; Tanji, K.K.

    2006-01-01

    Elevated concentrations of arsenic (As) in shallow groundwater in Tulare Basin pose an environmental risk because of the carcinogenic properties of As and the potential for its migration to deep aquifers that could serve as a future drinking water source. Adsorption and desorption are hypothesized to be the major processes controlling As solubility in oxidized surface sediments where arsenate [As(V)] is dominant. This study examined the relationship between sorption processes and arsenic solubility in shallow sediments from the dry Tulare Lake bed by determining sorption isotherms, pH effect on solubility, and desorption-readsorption behavior (hysteresis), and by using a surface complexation model to describe sorption. The sediments showed a high capacity to adsorb As(V). Estimates of the maximum adsorption capacity were 92 mg As kg- 1 at pH 7.5 and 70 mg As kg- 1 at pH 8.5 obtained using the Langmuir adsorption isotherm. Soluble arsenic [> 97% As(V)] did not increase dramatically until above pH 10. In the native pH range (7.5-8.5), soluble As concentrations were close to the lowest, indicating that As was strongly retained on the sediment. A surface complexation model, the constant capacitance model, was able to provide a simultaneous fit to both adsorption isotherms (pH 7.5 and 8.5) and the adsorption envelope (pH effect on soluble As), although the data ranges are one order of magnitude different. A hysteresis phenomenon between As adsorbed on the sediment and As in solution phase was observed in the desorption-readsorption processes and differs from conventional hysteresis observed in adsorption-desorption processes. The cause is most likely due to modification of adsorbent surfaces in sediment samples upon extensive extractions (or desorption). The significance of the hysteresis phenomenon in affecting As solubility and mobility may be better understood by further microscopic studies of As interaction mechanisms with sediments subjected to extensive leaching in natural environments. ?? 2006 Elsevier B.V. All rights reserved.

  18. Laser speckle photometry: contactless nondestructive testing technique

    NASA Astrophysics Data System (ADS)

    Cikalova, Ulana; Nicolai, Juergen; Bendjus, Beatrice; Schreiber, Juergen

    2012-10-01

    Laser Speckle Photometry (LSP) is a newly developed contactless, fast and completely optical nondestructive testing method based on the detection and analysis of thermally or mechanically activated characteristic speckle dynamics. The heat propagation or tension process causes locally different degrees of thermal/mechanical expansion, which generates local and time-dependent strain fields, resulting in a local displacement of material surface. During this process, the normal surface slope and absolute height of the microscopic and mesoscopic surface segments, especially at rough sample surfaces, is transformed. These spatiotemporal changes include information about the material structure and conditions. Therefore, the proposed measurement technique includes a pulsed heating source for sample activation, a temperature detection of the sample at the measurement location in a distance from the heading point, a continuous wave laser for sample irradiation and activation of speckle patterns at the measurement point, and in addition, a fast CCD camera for the detection of the speckle movement during heat propagation at the measurement location. Laser Speckle Photometry can be used for evaluating material properties, such as hardness and porosity. The approach is based on the estimation of the "Speckle Thermal Diffusivity" parameter K, that can be determined using the thermal diffusion equation and the modified correlation function from the pixel intensity of the speckle image variations during thermal activation. After testing, the correlation between parameter K and hardness, and porosity respectively, was found. Furthermore, mechanical material stress changes, also at elevated operating temperatures, can be estimated by the presented technique using the calculated parameter K. In this case, the thermal excitation will be partially replaced by mechanical activation, such as the tension process. The technique of LSP and the results of calibration experiments are presented in this paper.

  19. Light-induced heterogeneous reactions of NO2 on indoor surfaces: How they affect the balance of nitrous acid

    NASA Astrophysics Data System (ADS)

    Gomez Alvarez, E.; Soergel, M.; Bassil, S.; Zetzsch, C.; Gligorovski, S.; Wortham, H.

    2011-12-01

    Nitrous acid (HONO) is an important indoor pollutant. The adverse health effects due to the formation of nitrosamines are well known. HONO acts as a nitrosating agent after wall reactions of HONO with nicotine [Sleiman et al., 2010]. Indoor air can be surprisingly rich in HONO (homes with fireplaces, stoves, gas heating and cooking) and also surfaces are abundant. High HONO concentrations have been measured in indoor environments, from the direct emissions and heterogeneous reactions of NO2 in darkness. However, the measured HONO concentrations do not correspond to the HONO levels determined by the models [Carslaw, 2007]. We have tested in a flow tube reactor on-line coupled to a NOx analyzer and a sensitive Long Path Absorption Photometry instrument, the behaviour of various indoor surfaces towards NO2 under simulated solar light irradiation (?= 300-700 nm). Our study has allowed us to obtain a deeper knowledge on the mechanisms of heterogeneous formation of HONO, quantifying the dependence of HONO formation on behalf of NO2 concentration and relative humidity and the enhancement of HONO formation in the presence of light. Pyrex, acidic detergent, alkaline detergent, paint and lacquer were tested on behalf of their heterogeneous reactivity towards NO2 in the absence and in presence of light. The results obtained demonstrated that indoor surfaces are photo-chemically active under atmospherically relevant conditions. The strongly alkaline surfaces (such as certain types of detergent) show a strong long-term uptake capacity. However, other surfaces such as detergents with a more acidic character released HONO. In some cases such as paint and varnish, a strong HONO release with light was detected, which was significantly higher than that obtained over clean glass surfaces. Certain organics present on their composition could exert a photo-sensitizing effect that may explain their increased reactivity. Unfortunately, the final balance points towards an important net production of HONO from organics usually applied on different indoor surfaces that add to the very powerful HONO production simply due to heterogeneous reactivity on bare indoor surfaces. The results of this study add to the increasing concern over the reactivity in indoor environments and in particular from the point of view of HONO formation kinetics.

  20. Overview of GAIA Multi-Color Photometry

    NASA Astrophysics Data System (ADS)

    Høg, Erik

    Gaia will obtain multi-color photometry for astrometric and astrophysical purposes. A photometry in five broad bands and with high angular resolution will be obtained after every astrometric observation of a star, especially for the sake of correcting slight astrometric chromaticity errors of the optical system. A separate smaller telescope will obtain photometry in eleven passbands of medium width designed to serve the astrophysical analysis of the mission results. The medium-band photometry (MBP) has less angular resolution, but much longer effective integration time than the broad-band photometry (BBP).

  1. BVRI Surface Photometry of Isolated Galaxy Triplets

    Microsoft Academic Search

    H. M. Hernández-Toledo; H. Méndez-Hernández; H. Aceves; L. Olguín

    2011-01-01

    Optical broadband BVRI observations of 54 galaxies selected from the Catalog of Isolated Triplets of Galaxies in the Northern Hemisphere have been carried out at San Pedro Mártir National Observatory to evaluate their photometric and morphological properties. We complement our analysis with Two-Micron All Sky Survey (2MASS) and Sloan Digital Sky Survey (SDSS) images and look for signatures likely related

  2. Photometry of meteorites

    NASA Astrophysics Data System (ADS)

    Beck, P.; Pommerol, A.; Thomas, N.; Schmitt, B.; Moynier, F.; Barrat, J.-A.

    2012-03-01

    We have measured the bi-directional reflectance phase function on selected meteorite samples (1 howardite, 1 eucrite, 1 diogenite, Orgeuil (CI), Tagish Lake (CC), Allende (CV), Lunar meteorite (MAC 88105), Forest Vale (H4)) covering part of the geochemical and petrologic diversity expected for asteroid surfaces. Samples were measured as powders, for which we achieved reflectance measurements from phase angles down to 3°, and up to 150°, at five different wavelengths covering the VIS-NIR spectral region. The data were fitted by the photometric model of Hapke (Hapke, B. [1993]. Theory of reflectance and emittance spectroscopy. Cambridge University Press, Cambridge). The physical sense of the retrieved Hapke’s parameters seems unclear but they permit to interpolate the data to any observation geometry. Strong opposition effects were observed for all samples. The absolute intensity of this effect appears moderately variable among our sample suite, and is not correlated with the average sample reflectance. We interpret this observation as Shadow-Hiding Opposition Effect (SHOE). In the case of samples presenting intense absorption bands (the Fe crystal field band at 1 ?m of HED and the ordinary chondrite), we observe significant dependence of band depth to phase angle, up to 70°, even for moderate variation of phase angle. In addition, a general trend of spectral reddening with phase angle is observed. This reddening, linear with phase angle, is present in all meteorites studied. This behavior is not predicted by classical radiative theories. We propose that small-scale roughness (of the order of or below the wavelength) may induce such a behavior.

  3. The surface characteristics of activated carbon as affected by ozone and alkaline treatment.

    PubMed

    Chiang, Hung-Lung; Huang, C P; Chiang, P C

    2002-04-01

    The surface chemical characteristics of activated carbon treated by ozone and alkaline are determined in terms of surface functional groups and surface acidity. Surface functional groups are analyzed by the IR spectroscopic method and Boehm's titration technique. The surface acidity of activated carbon is determined by electrophoretic mobility measurements. The oxygen concentration of activated carbon increases upon ozone and NaOH treatment. Surface functional groups increase mostly in the hydroxyl and carboxyl categories rather than the carbonyl category upon ozone and NaOH treatment. PMID:11996146

  4. Water-Induced Reconstruction that Affects Mobile Ions on the Surface of Calcite Treavor A. Kendall and Scot T. Martin*

    E-print Network

    Water-Induced Reconstruction that Affects Mobile Ions on the Surface of Calcite Treavor A. Kendall is exchanged between them and that both are loosely bound. Complementing the topographic images, polarization heights are simultaneously measured by polarization-force microscopy. The polarization heights

  5. Dynamics between fruit cuticles and surface microflora can affect sanitizing methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biofilms are communities of microorganisms held together by substances such as polysaccharides which form on surfaces. These communities do not need to be on living tissue but form on any available surface such as rocks in a stream, interior of pipes and on teeth. On surfaces, including fruit, these...

  6. Photocells, photomultipliers, and southern-hemisphere photometry.

    NASA Astrophysics Data System (ADS)

    Hearnshaw, J. B.

    1996-11-01

    Three aspects of the historical development of photoelectric photometry in astronomy are discussed. The first is the era of the diode photocell in astronomical photometry, which represents the forerunner of the application of the photomultiplier, and was the first serious attempt to use electronics at the telescope. Secondly, the early days of the photomultiplier are discussed, which, after World War II, brought about an instant revolution in the practice of photoelectric photometry. And finally, the arrival of photomultiplier photometry in the southern hemisphere from about 1950 will be discussed.

  7. Analysing Thermal Response Test Data Affected by Groundwater Flow and Surface Temperature Change

    NASA Astrophysics Data System (ADS)

    Verdoya, Massimo; Imitazione, Gianmario; Chiozzi, Paolo; Orsi, Marco; Armadillo, Egidio

    2014-05-01

    Tests that record the underground temperature variation due to a constant heat injected into a borehole (or extracted from it) by means of a carrier fluid are routinely performed to infer subsurface thermal conductivity and borehole thermal resistance, which are needed to size geothermal heat pump systems. The most popular model to analyse temperature-time curves obtained from these tests is the infinite line source (ILS). This model gives appropriate estimations of thermal parameters only if particular hydro-geological conditions are fulfilled. Several flaws can however affect data interpretation with ILS, which is based on strong assumptions like those of a purely conductive heat transfer regime in a homogeneous medium, no vertical heat flow and infinite length of the borehole. Other drawbacks can arise from the difficulty in the proper thermal insulation of the test equipment, and consequently with oscillations of the carrier fluid temperature due to surface temperature changes. In this paper, we focused on the treatment of thermal response test data when both advection and periodic changes of surface temperature occur. We used a moving line source model to simulate temperature-time signals under different hypothesis of Darcy velocity and thermal properties. A random noise was added to the signal in order to mimic high frequency disturbances, possibly caused by equipment operating conditions and/or geological variability. The subsurface thermal conductivity, the Darcy velocity and the borehole thermal resistance were inferred by minimising the root mean square error between the synthetic dataset and the theoretical model. The optimisation was carried out with the Nelder-Mead algorithm, and thermal and hydraulic properties were determined by iterative reprocessing according to a trial-and-error procedure. The inferred thermal and hydraulic parameters are well consistent with the 'a priory' values, and the presence of noise in the synthetic data does not produce instability. The same optimisation procedure was also applied to interpret the synthetic signal with the ILS model. In case of Darcy velocity of the order of 10-6 m s-1, ILS largely overestimates thermal conductivity. The optimisation analysis was then applied to real thermal response tests carried out in boreholes drilled in sedimentary formation aquifers, whose volume heat capacity was assumed to be known. These data showed a periodic offset in the recorded temperature-time series. A Fourier analysis allowed the recognition of harmonic contributions with period of about 12 and 24 hours. These oscillations appeared to be coherent with the data of air temperature change recorded at the test sites. The temperature-time curves were then filtered to remove the disturbing spectral components associated to a non-optimal thermostatic behaviour of the apparatus. This produced reliable estimates of thermal conductivity, Darcy velocity and borehole thermal resistance. The magnitude of the inferred groundwater flow was also checked by means of an independent method based on the analysis of temperature-depth logs recorded prior to the thermal tests, under thermal equilibrium conditions.

  8. pysynphot: Synthetic photometry software package

    NASA Astrophysics Data System (ADS)

    STScI development Team

    2013-03-01

    pysynphot is a synthetic photometry software package suitable for either library or interactive use. Intended as a modern-language successor to the IRAF/STSDAS synphot package, it provides improved algorithms that address known shortcomings in synphot, and its object-oriented design is more easily extensible than synphot's task-oriented approach. It runs under PyRAF, and a backwards compatibility mode is provided that recognizes all spectral and throughput tables, obsmodes, and spectral expressions used by synphot, to facilitate the transition for legacy code.

  9. Photometry of astrometric reference stars

    NASA Technical Reports Server (NTRS)

    Castelaz, Michael W.; Persinger, Tim; Stein, John W.; Prosser, James; Powell, Harry D.

    1991-01-01

    UBVRI, DDO, and uvby, H-beta photometry of astrometric reference stars is presented. Spectral types and luminosity classifications made from the colors are used to determine their spectroscopic parallaxes. In this paper, colors for 309 stars in 25 regions are given, and classifications for 210 stars have been made. These stars form reference frames in the Allegheny Observatory Multichannel Astrometric Photometer astrometric program, and in the Praesepe cluster reduced by Russell (1976). It is found that the present photometric spectral types are reliable to within 2.5 spectral subclasses.

  10. The Panchromatic Hubble Andromeda Treasury. X. Ultraviolet to Infrared Photometry of 117 Million Equidistant Stars

    NASA Astrophysics Data System (ADS)

    Williams, Benjamin F.; Lang, Dustin; Dalcanton, Julianne J.; Dolphin, Andrew E.; Weisz, Daniel R.; Bell, Eric F.; Bianchi, Luciana; Byler, Nell; Gilbert, Karoline M.; Girardi, Léo; Gordon, Karl; Gregersen, Dylan; Johnson, L. C.; Kalirai, Jason; Lauer, Tod R.; Monachesi, Antonela; Rosenfield, Philip; Seth, Anil; Skillman, Eva

    2014-11-01

    We have measured stellar photometry with the Hubble Space Telescope Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys in near ultraviolet (F275W, F336W), optical (F475W, F814W), and near infrared (F110W, F160W) bands for 117 million resolved stars in M31. As part of the Panchromatic Hubble Andromeda Treasury survey, we measured photometry with simultaneous point-spread function (PSF) fitting across all bands and at all source positions after precise astrometric image alignment (<5-10 mas accuracy). In the outer disk, the photometry reaches a completeness-limited depth of F475W ~ 28, while in the crowded, high surface brightness bulge, the photometry reaches F475W ~ 25. We find that simultaneous photometry and optimized measurement parameters significantly increase the detection limit of the lowest-resolution filters (WFC3/IR) providing color-magnitude diagrams (CMDs) that are up to 2.5 mag deeper when compared with CMDs from WFC3/IR photometry alone. We present extensive analysis of the data quality including comparisons of luminosity functions and repeat measurements, and we use artificial star tests to quantify photometric completeness, uncertainties and biases. We find that the largest sources of systematic error in the photometry are due to spatial variations in the PSF models and charge transfer efficiency corrections. This stellar catalog is the largest ever produced for equidistant sources, and is publicly available for download by the community.

  11. Mechanism analysis of the affect the copper line surface roughness after FA/O alkaline barrier CMP

    NASA Astrophysics Data System (ADS)

    Jiaojiao, Gao; Yuling, Liu; Chenwei, Wang; Jin, Cui

    2014-12-01

    The surface roughness seriously affects the performance of devices after barrier CMP. Due to the high surface roughness of copper line, the local resistance of a device will be high when working, then the copper line will overheat prompting the generation of electro-migration and the circuit will lose efficacy. Reducing the surface roughness of the copper line in barrier CMP is still an important research topic. The main factors influencing the surface roughness of copper line in alkaline barrier slurry are analyzed in the paper. Aimed at influencing the law on the surface roughness of copper line, using a new type of alkaline barrier slurry with a different pH of the chelating agent and changing the content of non-ionic surfactant, we then analyze the influencing law both on the surface roughness of copper line, and the influence mechanism. The experimental results show that with a chelating agent with a low pH value in the barrier slurry, the surface roughness of the copper line is 1.03 nm and it is the lowest in all of the barrier slurries, and with the increase of non-ionic surfactant concentration, the surface roughness of copper line is reduced to 0.43 nm, meeting the demand of further development of integrated circuits.

  12. Induction effects for heterochromatic brightness matching, heterochromatic flicker photometry,

    E-print Network

    Dobkins, Karen R.

    Induction effects for heterochromatic brightness matching, heterochromatic flicker photometry flicker photometry (HFP), and minimally distinct border (MDB). For HBM, subjects varied the relative compared with those obtained on two other tasks: hetero- chromatic flicker photometry (HFP) and minimally

  13. Inflammatory cytokine release is affected by surface morphology and chemistry of titanium implants.

    PubMed

    Östberg, Anna-Karin; Dahlgren, Ulf; Sul, Young-Taeg; Johansson, Carina B

    2015-04-01

    To investigate in vitro cellular cytokine expression in relation to commercially pure titanium discs, comparing a native surface to a fluorinated oxide nanotube surface. Control samples pure titanium discs with a homogenous wave of the margins and grooves and an often smeared-out surface structure. Test samples pure titanium discs with a fluorinated titanium oxide chemistry and surface morphology with nanopore/tube geometry characterized by ordered structures of nanotubes with a diameter of ?120 nm, a spacing of ?30 nm, and a wall thickness of ?10 nm. Cross-section view showed vertically aligned nanotubes with similar lengths of ?700 nm. Peripheral blood mononuclear leucocytes were cultured for 1, 3, and 6 days according to standard procedures. BioPlex Pro™ assays were used for analysis and detection of cytokines. Selected inflammatory cytokines are reported. A pronounced difference in production of the inflammatogenic cytokines was observed. Leucocytes exposed to control coins produced significantly more TNF-?, IL-1ß, and IL-6 than the test nanotube coins. The effect on the TH2 cytokine IL-4 was less pronounced at day 6 compared to days 1 and 3, and slightly higher expressed on the control coins. The morphology and surface chemistry of the titanium surface have a profound impact on basic cytokine production in vitro. Within the limitations of the present study, it seems that the fluorinated oxide nanotube surface results in a lower inflammatory response compared to a rather flat surface that seems to favour inflammation. PMID:25779512

  14. Nanoscale Roughness and Morphology Affect the IsoElectric Point of Titania Surfaces

    PubMed Central

    Borghi, Francesca; Vyas, Varun; Podestà, Alessandro; Milani, Paolo

    2013-01-01

    We report on the systematic investigation of the role of surface nanoscale roughness and morphology on the charging behaviour of nanostructured titania (TiO2) surfaces in aqueous solutions. IsoElectric Points (IEPs) of surfaces have been characterized by direct measurement of the electrostatic double layer interactions between titania surfaces and the micrometer-sized spherical silica probe of an atomic force microscope in NaCl aqueous electrolyte. The use of a colloidal probe provides well-defined interaction geometry and allows effectively probing the overall effect of nanoscale morphology. By using supersonic cluster beam deposition to fabricate nanostructured titania films, we achieved a quantitative control over the surface morphological parameters. We performed a systematical exploration of the electrical double layer properties in different interaction regimes characterized by different ratios of characteristic nanometric lengths of the system: the surface rms roughness Rq, the correlation length ? and the Debye length ?D. We observed a remarkable reduction by several pH units of IEP on rough nanostructured surfaces, with respect to flat crystalline rutile TiO2. In order to explain the observed behavior of IEP, we consider the roughness-induced self-overlap of the electrical double layers as a potential source of deviation from the trend expected for flat surfaces. PMID:23874708

  15. Surface and Subsurface Geologic Risk Factors to Ground Water Affecting Brownfield Redevelopment Potential

    Microsoft Academic Search

    Martin M. Kaufman; Kent S. Murray; Daniel T. Rogers

    2003-01-01

    brownfields. The model is derived from a space and time conceptual framework that identifies and measures the surface and subsurface risk the substances released on and just below the surface factors present at brownfield sites. The model then combines these by human activity and their interactions with the near- factors with a contamination extent multiplier at each site to create

  16. Fast photometry with small telescopes

    NASA Astrophysics Data System (ADS)

    Kanbach, G.; Rau, A.; S?owikowska, A.

    2014-03-01

    Facility instruments on major telescopes rarely provide photometry on timescales into the sub-second range. The development of dedicated high-time resolution detectors that could be attached as guest instruments was therefore natural to follow up with optical observations on many highly time variable astronomical objects. Such sources were often discovered first in the radio range (e.g. pulsars, quasars) or with X- and gamma-ray satellites (X-ray binaries, cataclysmic variables, gamma-ray bursts). Although telescopes in the 4 - 8m class would be nice to have for high-time resolution astronomy (HTRA) the access is often oversubscribed. Many currently active HTRA instruments were started on smaller telescopes in the 1-3m class, which provide the flexibility and observation time needed for the observation of highly variable stars. We describe the basic detector types, i.e. fast imaging or photon counting, and current projects. Based on our experience with the fast timing photo-polarimeter OPTIMA (Optical Timing Analyzer), we review some observational constraints on meter-class telescopes. We demonstrate the 'scientific power' of very fast photometry, done with OPTIMA and similar systems on small telescopes, with selected results for a black hole binary, an optical transient magnetar, and the Crab pulsar. %

  17. An optimal extraction algorithm for imaging photometry

    Microsoft Academic Search

    Tim Naylor

    1998-01-01

    This paper is primarily an investigation of whether the `optimal extraction' techniques used in CCD spectroscopy can be applied to imaging photometry. It is found that using such techniques provides a gain of around 10 per cent in signal-to-noise ratio over normal aperture photometry. Formally, it is shown to be equivalent to profile fitting, but offers advantages of robust error

  18. Substrate material affects wettability of surfaces coated and sintered with silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Wei, Kang; Zeng, Hansong; Zhao, Yi

    2013-05-01

    Silica nanoparticles coating and sintering is a widely-used approach for creating hydrophobic and superhydrophobic surfaces. The role of substrate material in this process, however, has not been thoroughly investigated. In this work, the role of substrate material is examined by measuring surface wettability of three different substrate materials (glass, polyimide and copper) under systematically varied conditions. These surfaces are modulated from hydrophilic (water contact angle (WCA) < 90°) to superhydrophobic (WCA > 150°) by coating and sintering silica nanoparticles, followed by assembling a layer of fluorine compound. Static WCA characterization shows that surface wettability is not solely dependent on the concentration of the coating colloidal, but is also on the substrate material. In particular, copper substrate exhibits a larger WCA than glass and polyimide substrates. Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS) and Atomic Force Microscopy (AFM) characterizations show that the substrate material-dependent wettability is attributed to thermal-induced nanostructures on the copper surface, which contributes to the hierarchical micro-/nano- topography. This finding is important for designing hydrophobic/superhydrophobic surfaces comprised of different materials, especially those that would experience thermal cycles in surface functionalization and subsequent use.

  19. Changes in droplet surface tension affect the observed hygroscopicity of photochemically aged biomass burning aerosol.

    PubMed

    Giordano, Michael R; Short, Daniel Z; Hosseini, Seyedehsan; Lichtenberg, William; Asa-Awuku, Akua A

    2013-10-01

    This study examines the hygroscopic and surface tension properties as a function of photochemical aging of the aerosol emissions from biomass burning. Experiments were conducted in a chamber setting at the UC-Riverside Center for Environmental Research and Technology (CE-CERT) Atmospheric Processes Lab using two biomass fuel sources, manzanita and chamise. Cloud condensation nuclei (CCN) measurements and off-line filter sample analysis were conducted. The water-soluble organic carbon content and surface tension of the extracted filter samples were measured. Surface tension information was then examined with Köhler theory analysis to calculate the hygroscopicity parameter, ?. Laboratory measurement of biomass burning smoke from two chaparral fuels is shown to depress the surface tension of water by 30% or more at organic matter concentrations relevant at droplet activation. Accounting for surface tension depression can lower the calculated ? by a factor of 2. This work provides evidence for surface tension depression in an important aerosol system and may provide closure for differing sub- and supersaturated ? measurements. PMID:23957441

  20. How Do Silanes Affect the Lubricating Properties of Cationic Double Chain Surfactant on Silica Surfaces ?

    E-print Network

    Paris-Sud XI, Université de

    1 How Do Silanes Affect the Lubricating Properties of Cationic Double Chain Surfactant on Silica of an aminosilane on the lubricant properties of a C18 double-chained cationic surfactant has been investigated in the sizing and in the pure cationic surfactant solution. The aminosilane on its own has no lubricant property

  1. Theory of wide-angle photometry from standard stars

    NASA Technical Reports Server (NTRS)

    Usher, Peter D.

    1989-01-01

    Wide angle celestial structures, such as bright comet tails and nearby galaxies and clusters of galaxies, rely on photographic methods for quantified morphology and photometry, primarily because electronic devices with comparable resolution and sky coverage are beyond current technological capability. The problem of the photometry of extended structures and of how this problem may be overcome through calibration by photometric standard stars is examined. The perfect properties of the ideal field of view are stated in the guise of a radiometric paraxial approximation, in the hope that fields of view of actual telescopes will conform. Fundamental radiometric concepts are worked through before the issue of atmospheric attenuation is addressed. The independence of observed atmospheric extinction and surface brightness leads off the quest for formal solutions to the problem of surface photometry. Methods and problems of solution are discussed. The spectre is confronted in the spirit of standard stars and shown to be chimerical in that light, provided certain rituals are adopted. After a brief discussion of Baker-Sampson polynomials and the vexing issue of saturation, a pursuit is made of actual numbers to be expected in real cases. While the numbers crunched are gathered ex nihilo, they demonstrate the feasibility of Newton's method in the solution of this overdetermined, nonlinear, least square, multiparametric, photometric problem.

  2. Abiotic Factors Affecting the Persistence of Avian Influenza Virus in Surface Waters of Waterfowl Habitats

    PubMed Central

    Dalton, Melinda S.; Cressler, Alan M.; Berghaus, Roy D.; Stallknecht, David E.

    2014-01-01

    Avian influenza (AI) virus can remain infectious in water for months, and virus-contaminated surface water is considered to be a source of infection within wild waterfowl populations. Previous work has characterized the effects of pH, salinity, and temperature on viral persistence in water, but most of that work was done with modified distilled water. The objective of this study was to identify the abiotic factors that influence the duration of AI virus persistence in natural surface water. Surface water samples were collected from 38 waterfowl habitats distributed across the United States. Samples were submitted to the U.S. Geological Survey National Water Quality Laboratory for chemical analysis and the University of Georgia for viral reduction time analysis. Samples were filtered with 0.22-?m filters, and the durations of persistence of three wild-bird-derived influenza A viruses within each water sample at 10, 17, and 28°C were determined. The effects of the surface water physicochemical factors on the duration of AI viral persistence in laboratory experiments were evaluated by multivariable linear regression with robust standard errors. The duration of AI virus persistence was determined to be longest in filtered surface water with a low temperature (<17°C), a neutral-to-basic pH (7.0 to 8.5), low salinity (<0.5 ppt), and a low ammonia concentration (<0.5 mg/liter). Our results also highlighted potential strain-related variation in the stability of AI virus in surface water. These results bring us closer to being able to predict the duration of AI virus persistence in surface water of waterfowl habitats. PMID:24584247

  3. Abiotic factors affecting the persistence of avian influenza virus in surface waters of waterfowl habitats.

    PubMed

    Keeler, Shamus P; Dalton, Melinda S; Cressler, Alan M; Berghaus, Roy D; Stallknecht, David E

    2014-05-01

    Avian influenza (AI) virus can remain infectious in water for months, and virus-contaminated surface water is considered to be a source of infection within wild waterfowl populations. Previous work has characterized the effects of pH, salinity, and temperature on viral persistence in water, but most of that work was done with modified distilled water. The objective of this study was to identify the abiotic factors that influence the duration of AI virus persistence in natural surface water. Surface water samples were collected from 38 waterfowl habitats distributed across the United States. Samples were submitted to the U.S. Geological Survey National Water Quality Laboratory for chemical analysis and the University of Georgia for viral reduction time analysis. Samples were filtered with 0.22-?m filters, and the durations of persistence of three wild-bird-derived influenza A viruses within each water sample at 10, 17, and 28°C were determined. The effects of the surface water physicochemical factors on the duration of AI viral persistence in laboratory experiments were evaluated by multivariable linear regression with robust standard errors. The duration of AI virus persistence was determined to be longest in filtered surface water with a low temperature (<17°C), a neutral-to-basic pH (7.0 to 8.5), low salinity (<0.5 ppt), and a low ammonia concentration (<0.5 mg/liter). Our results also highlighted potential strain-related variation in the stability of AI virus in surface water. These results bring us closer to being able to predict the duration of AI virus persistence in surface water of waterfowl habitats. PMID:24584247

  4. How does the deposition of gas phase species affect surface pH at frozen salty interfaces?

    NASA Astrophysics Data System (ADS)

    Donaldson, D. J.; Wren, S. N.

    2012-12-01

    Chemical processes occurring on snow and ice surfaces play an important role in controlling the oxidative capacity of the overlying atmosphere. However, efforts to gain a better, mechanistic understanding of such processes are impeded by a poor understanding of the chemical nature of the air-ice interface. In consequence, constraining the substrates that are most relevant to these processes (e.g., new sea ice, first-year ice, frost flowers, brine layers, saline snow) as well as understanding how chemistry will be affected as the areal extent of these substrates succumbs to polar environmental change, remains difficult. In this study, we used glancing-angle laser-induced fluorescence and a surface-active fluorescent pH indicator to investigate how the nature of the ice, whether frozen pure water, salt water or seawater, influences pH changes at the surface. We find that deposition of HCl(g) leads to a very different pH response at the frozen pure water surface than at the frozen salt water surface indicating that these two surfaces present different chemical environments. Results indicate that the frozen salt water surface is covered by a brine layer which behaves like a true liquid layer. On the other hand, the disordered interface at the pure ice surface presents a unique chemical environment. Our results also suggest that the sea ice surface is buffered against pH changes arising from the deposition of gas phase species. These results have important implications for understanding pH-sensitive processes occurring at the air-ice boundary, such as bromine activation.

  5. Cholesterol level affects surface charge of lipid membranes in saline solution

    PubMed Central

    Magarkar, Aniket; Dhawan, Vivek; Kallinteri, Paraskevi; Viitala, Tapani; Elmowafy, Mohammed; Róg, Tomasz; Bunker, Alex

    2014-01-01

    Cholesterol is an important component of all biological membranes as well as drug delivery liposomes. We show here that increasing the level of cholesterol in a phospholipid membrane decreases surface charge in the physiological environment. Through molecular dynamics simulation we have shown that increasing the level of cholesterol decreases Na+ ion binding. Complementary experimental ? – potential measurements have shown a decreased ? – potential with increasing cholesterol content, indicative of reduced surface charge. Both experiments and simulations have been carried out on both saturated 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and monounsaturated 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membranes. This result is particularly important because membrane surface charge plays an important role in the interactions of biomembranes with peripheral membrane proteins and drug delivery liposomes with the immune system. PMID:24845659

  6. Polarimetric Retrievals of Surface and Cirrus Clouds Properties in the Region Affected by the Deepwater Horizon Oil Spill

    NASA Technical Reports Server (NTRS)

    Ottaviani, Matteo; Cairns, Brian; Chowdhary, Jacek; Van Diedenhoven, Bastiaan; Knobelspiesse, Kirk; Hostetler, Chris; Ferrare, Rich; Burton, Sharon; Hair, John; Obland, Michael D.; Rogers, Raymond

    2012-01-01

    In 2010, the Goddard Institute for Space Studies (GISS) Research Scanning Polarimeter (RSP) performed several aerial surveys over the region affected by the oil spill caused by the explosion of the Deepwater Horizon offshore platform. The instrument was deployed on the NASA Langley B200 aircraft together with the High Spectral Resolution Lidar (HSRL), which provides information on the distribution of the aerosol layers beneath the aircraft, including an accurate estimate of aerosol optical depth. This work illustrates the merits of polarization measurements in detecting variations of ocean surface properties linked to the presence of an oil slick. In particular, we make use of the degree of linear polarization in the glint region, which is severely affected by variations in the refractive index but insensitive to the waviness of the water surface. Alterations in the surface optical properties are therefore expected to directly affect the polarization response of the RSP channel at 2264 nm, where both molecular and aerosol scattering are negligible and virtually all of the observed signal is generated via Fresnel reflection at the surface. The glint profile at this wavelength is fitted with a model which can optimally estimate refractive index, wind speed and direction, together with aircraft attitude variations affecting the viewing geometry. The retrieved refractive index markedly increases over oil-contaminated waters, while the apparent wind speed is significantly lower than in adjacent uncontaminated areas, suggesting that the slick dampens high-frequency components of the ocean wave spectrum. The constraint on surface reflectance provided by the short-wave infrared channels is a cornerstone of established procedures to retrieve atmospheric aerosol microphysical parameters based on the inversion of the RSP multispectral measurements. This retrieval, which benefits from the ancillary information provided by the HSRL, was in this specific case hampered by prohibitive variability in atmospheric conditions (very inhomogeneous aerosol distribution and cloud cover). Although the results presented for the surface are essentially unaffected, we discuss the results obtained by typing algorithms in sorting the complex mix of aerosol types, and show evidence of oriented ice in cirrus clouds present in the area. In this context, polarization measurements at 1880 nm were used to infer ice habit and cirrus optical depth, which was found in the subvisual/threshold-visible regime, confirming the utility of the aforementioned RSP channel for the remote sensing of even thin cold clouds.

  7. Surface and ground water quality in a restored urban stream affected by road salts

    EPA Science Inventory

    In 2001 research began in Minebank Run, MD to examine the impact of restoration on water quality. Our research area was to determine if road salts in the surface and ground waters are detrimental to the stream channel restoration. The upstream reach (UP), above the Baltimore I-...

  8. EFFECTS OF GRAZING MANAGEMENT ON PASTURE CHARACTERISTICS AFFECTING SEDIMENT AND NUTRIENT LOADS IN SURFACE WATERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To evaluate cattle grazing effects on the potential for sediment and nutrient loading of surface waters, forage cover, sward height, and mass and manure cover were measured in pastures with different grazing management systems. Six 12.1-ha cool-season grass pastures were assigned one of three treat...

  9. Oxidation rate of iron sulfides as affected by surface area, morphology, oxygen concentration and autotrophic bacteria

    Microsoft Academic Search

    C. E. PUGH; L. R. HOSSNER; J. B. DIXON

    1984-01-01

    The relationship between surface area and rate of oxidation of Fe sulphides (pyrite and marcasite) separated from Texas lignite was studied. The reaction kinetics with respect to Fe sulphide morphology and particle size were evaluated. The oxygen concentration and the presence of autotrophic Fe and S-oxidizing bacteria (thiobacillus ferro-oxidans) on the rate of oxidation were also evaluated. The formation of

  10. Implant surface treatments affect gene expression of Runx2, osteogenic key marker

    PubMed Central

    Na, Young; Heo, Seong-Joo; Kim, Seong-Kyun

    2009-01-01

    STATEMENT OF PROBLEM The aim of this study was to study the effects of various surface treatments to a titanium surface on the expression of Runx2 in vitro. MATERIAL AND METHODS Human Osteosarcoma TE-85 cells were cultured on machined, sandblasted, or anodic oxidized cpTi discs. At various times of incubation, the cells were collected and then processed for the analysis of mRNA expression of Runx2 using reverse transcription-PCR. RESULTS The expression pattern of Runx2 mRNA was differed according to the types of surface treatment. When the cells were cultured on the untreated control culture plates, the gene expression of Runx2 was not increased during the experiments. In the case of that the cells were cultured on the machined cpTI discs, the expression level was intermediate at the first day, but increased constitutively to day 5. In cells on sandblasted cpTi discs, the expression level was highest in the first day sample and the level was maintained to 5 days. In cells on anodized cpTi discs, the expression level increased rapidly to 3 days, but decreased slightly in the 5-th day sample. CONCLUSION Different surface treatments may contribute to the regulation of osteoblast function by influencing the level of gene expression of key osteogenic factors. PMID:21165261

  11. Role of surface recombination in affecting the efficiency of nanostructured thin-film solar cells.

    PubMed

    Da, Yun; Xuan, Yimin

    2013-11-01

    Nanostructured light trapping is a promising way to improve the efficiency in thin-film solar cells recently. In this work, both the optical and electrical properties of thin-film solar cells with 1D periodic grating structure are investigated by using photoelectric coupling model. It is found that surface recombination plays a key role in determining the performance of nanostructured thin-film solar cells. Once the recombination effect is considered, the higher optical absorption does not mean the higher conversion efficiency as most existing publications claimed. Both the surface recombination velocity and geometric parameters of structure have great impact on the efficiency of thin-film solar cells. Our simulation results indicate that nanostructured light trapping will not only improve optical absorption but also boost the surface recombination simultaneously. Therefore, we must get the tradeoffs between optical absorption and surface recombination to obtain the maximum conversion efficiency. Our work makes it clear that both the optical absorption and electrical recombination response should be taken into account simultaneously in designing the nanostructured thin-film solar cells. PMID:24514926

  12. Retention of potentially mobile radiocesium in forest surface soils affected by the Fukushima nuclear accident

    PubMed Central

    Koarashi, Jun; Moriya, Koichi; Atarashi-Andoh, Mariko; Matsunaga, Takeshi; Fujita, Hiroki; Nagaoka, Mika

    2012-01-01

    The fate of 137Cs derived from the Fukushima nuclear accident fallout and associated radiological hazards are largely dependent on its mobility in the surface soils of forest ecosystems. Thus, we quantified microbial and adsorptive retentions of 137Cs in forest surface (0–3 cm) soils. The K2SO4 extraction process liberated 2.1%–12.8% of the total 137Cs from the soils. Two soils with a higher content of clay- and silt-sized particles, organic carbon content, and cation exchange capacity showed higher 137Cs extractability. Microbial biomass was observed in all of the soils. However, the 137Cs extractability did not increase after destruction of the microbial biomass by chloroform fumigation, providing no evidence for microbial retention of the Fukushima-fallout 137Cs. The results indicate that uptake of 137Cs by soil microorganisms is less important for retention of potentially mobile 137Cs in the forest surface soils compared to ion-exchange adsorption on non-specific sites provided by abiotic components. PMID:23256039

  13. N-acetyl-L-cysteine affects growth, extracellular polysaccharide production, and bacterial biofilm formation on solid surfaces.

    PubMed

    Olofsson, Ann-Cathrin; Hermansson, Malte; Elwing, Hans

    2003-08-01

    N-Acetyl-L-cysteine (NAC) is used in medical treatment of patients with chronic bronchitis. The positive effects of NAC treatment have primarily been attributed to the mucus-dissolving properties of NAC, as well as its ability to decrease biofilm formation, which reduces bacterial infections. Our results suggest that NAC also may be an interesting candidate for use as an agent to reduce and prevent biofilm formation on stainless steel surfaces in environments typical of paper mill plants. Using 10 different bacterial strains isolated from a paper mill, we found that the mode of action of NAC is chemical, as well as biological, in the case of bacterial adhesion to stainless steel surfaces. The initial adhesion of bacteria is dependent on the wettability of the substratum. NAC was shown to bind to stainless steel, increasing the wettability of the surface. Moreover, NAC decreased bacterial adhesion and even detached bacteria that were adhering to stainless steel surfaces. Growth of various bacteria, as monocultures or in a multispecies community, was inhibited at different concentrations of NAC. We also found that there was no detectable degradation of extracellular polysaccharides (EPS) by NAC, indicating that NAC reduced the production of EPS, in most bacteria tested, even at concentrations at which growth was not affected. Altogether, the presence of NAC changes the texture of the biofilm formed and makes NAC an interesting candidate for use as a general inhibitor of formation of bacterial biofilms on stainless steel surfaces. PMID:12902275

  14. Surface variations affecting human dental enamel studied using nanomechanical and chemical analysis

    NASA Astrophysics Data System (ADS)

    Dickinson, Michelle Emma

    The enamel surface is the interface between the tooth and its ever changing oral environment. Cavity (caries) formation and extrinsic tooth staining are due, respectively, to degradation of the enamel structure under low pH conditions and interactions between salivary pellicle and dietary elements. Both of these occur at the enamel surface and are caused by the local environment changing the chemistry of the surface. The results can be detrimental to the enamel's mechanical integrity and aesthetics. Incipient carious lesions are the precursor to caries and form due to demineralisation of enamel. These carious lesions are a reversible structure where ions (e.g. Ca2+, F -) can diffuse in (remineralisation) to preserve the tooth's structural integrity. This investigation used controlled in vitro demineralisation and remineralisation to study artificial carious lesion formation and repair. The carious lesions were cross-sectioned and characterised using nanoindentation, electron probe micro-analysis and time of flight secondary ion mass spectrometry. Mechanical and chemical maps showed the carious lesion had a significantly reduced hardness and elastic modulus, and the calcium and phosphate content was lower than in sound enamel. Fluoride based remineralisation treatments gave a new phase (possibly fluorohydroxyapatite) within the lesion with mechanical properties higher than sound enamel. The acquired salivary pellicle is a protein-rich film formed by the physisorption of organic molecules in saliva onto the enamel surface. Its functions include lubrication during mastication and chemical protection. However, pellicle proteins react with dietary elements such as polyphenols (tannins in tea) causing a brown stain. This study has used in vitro dynamic nanoindentation and atomic force microscopy to examine normal and stained pellicles formed in vivo. The effects of polyphenols on the pellicle's mechanical properties and morphology have been studied. It was found that the initial adsorption of proteins occurred within 30 seconds of exposure to the oral cavity; fully mature pellicles develop in 2 hours. Polyphenol staining resulted in substantial changes in the morphology and mechanical properties of the pellicle. Specifically, staining gives pellicles consisting of large globules with high surface adhesion and a high loss tangent. These changes help explain why extrinsic stains are difficult to remove abrasively.

  15. An Introduction to Astronomical Photometry Using CCDs W. Romanishin

    E-print Network

    Masci, Frank

    An Introduction to Astronomical Photometry Using CCDs W. Romanishin University of Oklahoma wjr for the college astrophysics major to photometry in the optical region of the spectrum of astronomical objects telescope time as photometry. That said, it is still obvious that imaging photometry is an important part

  16. An Introduction to Astronomical Photometry Using CCDs W. Romanishin

    E-print Network

    Ellingson, Steven W.

    An Introduction to Astronomical Photometry Using CCDs W. Romanishin University of Oklahoma wjr astrophysics major to photometry in the optical region of the spectrum of astronomical objects using CCD telescope time as photometry. That said, it is still obvious that imaging photometry is an important part

  17. Crowded-field photometry from HST-imaging

    E-print Network

    Marianne Sodemann; Bjarne Thomsen

    1997-04-29

    We present a thorough investigation of stellar photometry based on HST imaging of crowded fields at 85 and 10 arcsec from the centre of the high-surface brightness elliptical M32. The Principal Investigators of the present archive data have elsewhere presented an impressive colour-magnitude diagram of the field at 85 arcsec. Based on the same data we enlarge on their photometric analysis and supplement with error estimators that more clearly show the implications of severe image crowding on the stellar photometry. We show that the faintest stars (I>25.0, V>26.0) are found too bright by several tens of a magnitude. For the field at 10 arcsec we conclude that it is not possible to obtain reliable stellar photometry, standard deviations being larger than 0.4 mag. Artificial-star experiments show that only very few of the brightest stars of the luminosity function can be expected to represent single objects, the majority being either spurious or not as bright as measured.

  18. Factors affecting hyporheic and surface transient storage in a western U.S. river

    NASA Astrophysics Data System (ADS)

    Johnson, Zachary C.; Warwick, John J.; Schumer, Rina

    2014-03-01

    Hyporheic storage accounts for a significant fraction of solute residence time in small streams and has been shown to have a large effect on the transport of solutes. It is not clear whether this characteristic is preserved in larger streams and rivers, as increased discharge and decreased slope may reduce overall exchange between the channel and subsurface, and the size of surface storage zones may increase. Conservative tracer tests conducted in the Truckee River, a stream with mean annual discharge >0.5 m3 s-1, were simulated with both one (1-SZ) and two-storage zone (2-SZ) transport models to quantify the relative role of surface transient storage (STS) and hyporheic transient storage (HTS) on the physical transport of solutes in a large stream. Tracer injections were conducted at two different discharge levels in two reaches with distinct geomorphic characteristics. STS was the dominant storage mechanism for all reaches and discharge levels and surface storage accounted for a larger fraction of median transport time (FMED200) than hyporheic storage in all but one case. Increased discharge significantly reduced the influence of the HTS (primarily) and STS zones on median transport time at the study site. Comparisons with studies of discharge and geomorphic effects on TS characteristics in other streams indicated differing physical controls on STS and HTS zones. Therefore, measurements such as slope, sinuosity, width, depth, and gross gains and losses of discharge need to be considered along with discharge. This work adds to the growing sentiment that up-scaling and prediction of stream storage characteristics based on discharge and channel properties is far from straightforward. Since biogeochemical processing occurs differently in the HTS and STS, two-zone storage models provide necessary representations of transport in river systems for studies focused on aspects of water quality. Extra parameters are required for model optimization but simple cross-section surveys (area and velocity) provide enough information to ensure enhanced parameter reliability.

  19. A study on stress affecting the microwave surface resistance of YBCO high temperature superconducting thin films

    Microsoft Academic Search

    Li-Bin Shi; Cui-Yan Xu; Guo-Hua Zhang

    2008-01-01

    We calculate stress in YBa2Cu3O7?x\\/MgO (YBCO\\/MgO) and YBa2Cu3O7?x\\/LaAlO3 (YBCO\\/LAO) by XRD of the sample, ?1=?1.2GPa and ?2=?1.4GPa, respectively, which shows that the stress in YBCO\\/LAO is stronger than that in YBCO\\/MgO. In addition, microwave response of the two pieces of thin films is also investigated by microstrip resonator technique. Surface resistance and penetration depth of the films are obtained by

  20. Thermal iodine release of surface-implanted iodine in zirconia and its affect on hull disposal

    NASA Astrophysics Data System (ADS)

    Brossard, F.; Chevarier, N.; Moncoffre, N.; Sainsot, Ph.; Crusset, D.; Jaffrezic, H.

    2000-06-01

    During the reactor processing fission products, among which iodine is one, are implanted by recoil inside the Zircaloy cladding tube, most of them being distributed within the first 2 ?m. At the same time, oxidation of the cladding tubes occurs and therefore in the waste disposal phase zirconia will act as the first migration barrier. In order to analyse the mechanisms involved in iodine migration, stable and radioactive iodine atoms were introduced in oxidised zirconium samples by means of ion implantation at the near surface (mean range around 50 nm). Iodine thermal-release was measured either by Rutherford backscattering spectrometry (RBS) or ?-spectroscopy.

  1. BVRI PHOTOMETRY OF 53 UNUSUAL ASTEROIDS

    SciTech Connect

    Ye, Q.-Z., E-mail: tom6740@gmail.com [Department of Atmospheric Sciences, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou (China)

    2011-02-15

    We present the results of BVRI photometry and classification of 53 unusual asteroids, including 35 near-Earth asteroids (NEAs), 6 high eccentricity/inclination asteroids, and 12 recently identified asteroid-pair candidates. Most of these asteroids were not classified prior to this work. For the few asteroids that have been previously studied, the results are generally in agreement. In addition to observing and classifying these objects, we merge the results from severalphotometric/spectroscopic surveys to create the largest-ever sample with 449 spectrally classified NEAs for statistical analysis. We identify a 'transition point' of the relative number of C/X-like and S-like NEAs at H {approx} 18 {r_reversible} D {approx} 1 km with confidence level at {approx}95% or higher. We find that the C/X-like:S-like ratio for 18 {<=} H < 22 is about twice as high as that of H < 18 (0.33 {+-} 0.04 versus 0.17 {+-} 0.02), virtually supporting the hypothesis that smaller NEAs generally have less weathered surfaces (therefore less reddish appearance) due to younger collision ages.

  2. L' AND M' Photometry Of Ultracool Dwarfs

    NASA Technical Reports Server (NTRS)

    Marley, M. S.; Tsvetanov, Z. I.; Vrba, F. J.; Henden, A. A.; Luginbuhl, C. B.

    2004-01-01

    We have compiled L' (3.4-4.1 microns) and M' (4.6- 4.8 microns) photometry of 63 single and binary M, L, and T dwarfs obtained at the United Kingdom Infrared Telescope using the Mauna Kea Observatory filter set. This compilation includes new L' measurements of eight L dwarfs and 13 T dwarfs and new M' measurements of seven L dwarfs, five T dwarfs, and the M1 dwarf Gl 229A. These new data increase by factors of 0. 6 and 1.6, respectively, the numbers of ultracool dwarfs T (sub eff) photometry, and trigonometric parallaxes are available, and we estimate these quantities for nine other dwarfs whose parallaxes and flux-calibrated spectra have been obtained. BC(SUB K) is a well-behaved function of near-infrared spectral type with a dispersion of approx. 0.1 mag for types M6-T5 it is significantly more scattered for types T5-T9. T (sub eff) declines steeply and monotonically for types M6-L7 and T4-T9, but it is nearly constant at approx. 1450 K for types L7-T4 with assumed ages of approx. 3 Gyr. This constant T(sub eff) is evidenced by nearly unchanging values of L'-M' between types L6 and T3. It also supports recent models that attribute the changing near-infrared luminosities and spectral features across the L-T transition to the rapid migration, disruption, and/or thinning of condensate clouds over a narrow range of T(sub eff). The L' and M' luminosities of early-T dwarfs do not exhibit the pronounced humps or inflections previously noted in l through K bands, but insufficient data exist for types L6-T5 to assert that M(Sub L') and M(sub M') are strictly monotonic within this range of typew. We compare the observed K, L', and M' luminosities of L and T dwarfs in our sample with those predicted by precipitation-cloud-free models for varying surface gravities and sedimentation efficiencies.

  3. A surface-exposed neuraminidase affects complement resistance and virulence of the oral spirochete Treponema denticola

    PubMed Central

    Kurniyati, Kurni; Zhang, Weiyan; Zhang, Kai; Li, Chunhao

    2013-01-01

    Neuraminidases (sialidases) catalyze the removal of terminal sialic acid from glycoconjugates. Bacterial pathogens often utilize neuraminidases to scavenge host sialic acid, which can be utilized either as a nutrient or as a decorating molecule to disguise themselves from host immune attacks. Herein, a putative neuraminidase (TDE0471) was identified in Treponema denticola, an oral spirochete associated with human periodontitis. TDE0471 is a cell surface-exposed exo-neuraminidase that removes sialic acid from human serum proteins; it is required for T. denticola to grow in a medium that mimics gingival crevice fluid, suggesting that the spirochete may use sialic acid as a nutrient in vivo. TDE0471 protects T. denticola from serum killing by preventing the deposition of membrane attack complexes on the bacterial cell surface. Animal studies revealed that a TDE0471-deficient mutant is less virulent than its parental wild-type strain in BALB/C mice. However, it causes a level of tissue damage similar to the wild type in complement-deficient B6.129S4-C3tm1Crr/J mice albeit the damage caused by both bacterial strains is more severe in these transgenic mice. Based on these results, we propose that T. denticola has evolved a strategy to scavenge host sialic acid using its neuraminidase, which allows the spirochete to acquire nutrients and evade complement killing. PMID:23808705

  4. A new capture fraction method to map how pumpage affects surface water flow

    USGS Publications Warehouse

    Leake, S.A.; Reeves, H.W.; Dickinson, J.E.

    2010-01-01

    All groundwater pumped is balanced by removal of water somewhere, initially from storage in the aquifer and later from capture in the form of increase in recharge and decrease in discharge. Capture that results in a loss of water in streams, rivers, and wetlands now is a concern in many parts of the United States. Hydrologists commonly use analytical and numerical approaches to study temporal variations in sources of water to wells for select points of interest. Much can be learned about coupled surface/groundwater systems, however, by looking at the spatial distribution of theoretical capture for select times of interest. Development of maps of capture requires (1) a reasonably well-constructed transient or steady state model of an aquifer with head-dependent flow boundaries representing surface water features or evapotranspiration and (2) an automated procedure to run the model repeatedly and extract results, each time with a well in a different location. This paper presents new methods for simulating and mapping capture using three-dimensional groundwater flow models and presents examples from Arizona, Oregon, and Michigan. Journal compilation ?? 2010 National Ground Water Association. No claim to original US government works.

  5. Structural mutation affecting intracellular transport and cell surface expression of murine class II molecules

    PubMed Central

    1988-01-01

    We have selected Ia variants from the Ia+ (H-2d) M12.4.1 B cell lymphoma that are negative on the cell surface for one or both Ia isotypes. The molecular analysis of two such independently selected cell lines, M12.A2 and M12.C3, is reported here. This analysis revealed that the genes encoding Ad beta (M12.A2) and Ed beta (M12.C3) contained identical single-nucleotide transitions that resulted in the substitution of Ser (mutant) for Asn (wild-type) at residue 82/83 of the extracellular NH2-terminal (membrane distal) beta 1 domain. This conservative substitution caused a cytoplasmic accumulation of I-A or I- E molecules in the respective cell line although predicted secondary- structure analysis suggests a minimal effect on protein conformation. Thus, the mutation appears to have either created a negative signal that stops transport or eliminated a positive signal that is required for transport and targeting to the cell surface. PMID:3126253

  6. WFPC2 aperture photometry and PSF modelling

    E-print Network

    N. R. Tanvir; D. R. T. Robinson; T. von Hippel

    1995-03-22

    Since the WFPC-2 undersamples the PSF, aperture photometry can produce results which are competetive with profile fitting in many situations. This article reports and investigation of aperture corrections using both real data and PSF models.

  7. WFPC2 Stellar Photometry with HSTphot

    E-print Network

    Andrew E. Dolphin

    2000-06-15

    HSTphot, a photometry package designed to handle the undersampled PSFs found in WFPC2 images, is introduced and described, as well as some of the considerations that have to be made in order to obtain accurate PSF-fitting stellar photometry with WFPC2 data. Tests of HSTphot's internal reliability are made using multiple observations of the same field, and tests of external reliability are made by comparing with DoPHOT reductions of the same data.

  8. WFPC2 Stellar Photometry with HSTphot

    Microsoft Academic Search

    2000-01-01

    HSTphot, a photometry package designed to handle the undersampled PSFs found\\u000ain WFPC2 images, is introduced and described, as well as some of the\\u000aconsiderations that have to be made in order to obtain accurate PSF-fitting\\u000astellar photometry with WFPC2 data. Tests of HSTphot's internal reliability are\\u000amade using multiple observations of the same field, and tests of external\\u000areliability

  9. WFPC2 Stellar Photometry with HSTphot

    NASA Technical Reports Server (NTRS)

    Dolphin, Andrew E.

    2000-01-01

    HSTphot, a photometry package designed to handle the undersampled PSFs found in WFPC2 images, is introduced and described, as well as some of the considerations that have to be made in order to obtain accurate PSF-fitting stellar photometry with WFPC2 data. Tests of HSTphot's internal reliability are made using multiple observations of the same field, and tests of external reliability are made by comparing with DoPHOT reductions of the same data. Subject headz'ngs: techniques: photometric

  10. Hyper: Hybrid photometry and extraction routine

    NASA Astrophysics Data System (ADS)

    Traficante, A.; Fuller, G. A.; Pineda, J. E.; Pezzuto, S.

    2015-02-01

    We present a new hybrid photometry and extraction routine called Hyper. It is designed to do compact source photometry, allowing for varying spatial resolution and sensitivity in multi-wavelength surveys. Hyper combines multi-Gaussian fitting with aperture photometry to provide reliable photometry in regions with variable backgrounds and in crowded fields. The background is evaluated and removed locally for each source using polynomial fits of various orders. Source deblending is done through simultaneous multi-Gaussian fitting of the main source and its companion(s), followed by the subtraction of the companion(s). Hyper also allows simultaneous multi-wavelength photometry by setting a fixed aperture size independent of the map resolution and by evaluating the source flux within the same region of the sky at multiple wavelengths at the same time. This new code has been initially designed for precise aperture photometry in complex fields such as the Galactic plane observed in the far infrared (FIR) by the Herschel infrared survey of the Galactic plane (Hi-GAL). Hyper has been tested on both simulated and real Herschel fields to quantify the quality of the source identification and photometry. The code is highly modular and fully parameterisable, therefore it can be easily adapted to different experiments. Comparison of the Hyper photometry with the catalogued sources in the Bolocam Galactic Plane Survey (BGPS), the 1.1 mm survey of the Galactic plane carried out with the Caltech Submillimeter Observatory, demonstrates the versatility of Hyper on different datasets. It is fast and light in its memory, and it is freely available to the scientific community.

  11. Superoxide Dismutase Activity in Pseudomonas putida Affects Utilization of Sugars and Growth on Root Surfaces

    PubMed Central

    Kim, Young Cheol; Miller, Charles D.; Anderson, Anne J.

    2000-01-01

    To investigate the role of superoxide dismutases (SOD) in root colonization and oxidative stress, mutants of Pseudomonas putida lacking manganese-superoxide dismutase (MnSOD) (sodA), iron-superoxide dismutase (FeSOD) (sodB), or both were generated. The sodA sodB mutant did not grow on components washed from bean root surfaces or glucose in minimal medium. The sodB and sodA sodB mutants were more sensitive than wild type to oxidative stress generated within the cell by paraquat treatment. In single inoculation of SOD mutants on bean, only the sodA sodB double mutant was impaired in growth on root surfaces. In mixed inoculations with wild type, populations of the sodA mutant were equal to those of the wild type, but levels of the sodB mutant and, to a great extent, the sodA sodB mutant, were reduced. Confocal microscopy of young bean roots inoculated with green fluorescent protein-tagged cells showed that wild type and SOD single mutants colonized well predominantly at the root tip but that the sodA sodB double mutant grew poorly at the tip. Our results indicate that FeSOD in P. putida is more important than MnSOD in aerobic metabolism and oxidative stress. Inhibition of key metabolic enzymes by increased levels of superoxide anion may cause the impaired growth of SOD mutants in vitro and in planta. PMID:10742227

  12. Design of peptidyl compounds that affect beta-amyloid aggregation: importance of surface tension and context.

    PubMed

    Gibson, Todd J; Murphy, Regina M

    2005-06-21

    Self-association of beta-amyloid (Abeta) peptide into cross-beta-sheet fibrils induces cellular toxicity in vitro and is linked with progression of Alzheimer's disease. Previously, we demonstrated that hybrid peptides, containing a recognition domain that binds to Abeta and a disrupting domain consisting of a chain of charged amino acids, inhibited Abeta-associated toxicity in vitro and increased the rate of Abeta aggregation. In this work we examine the design parameter space of the disrupting domain. Using KLVFFKKKKKK as a base case, we tested hybrid compounds with a branched rather than linear lysine oligomer, with l-lysine replaced by d-lysine, and with lysine replaced by diaminopropionic acid. We synthesized a compound with a novel anionic disrupting domain that contained cysteine thiols oxidized to sulfates, as well as other compounds in which alkyl or ether chains were appended to KLVFF. In all cases, the hybrid compound's ability to increase solvent surface tension was the strongest predictor of its effect on Abeta aggregation kinetics. Finally, we investigated the effects of arginine on Abeta aggregation. Arginine is a well-known chaotrope but increases surface tension of water. Arginine modestly decreased Abeta aggregation. In contrast, RRRRRR slightly, and KLVFFRRRRRR greatly, increased Abeta aggregation. Thus, the influence of arginine on Abeta aggregation depends strongly on the context in which it is presented. The effect of arginine, RRRRRR, and KLVFFRRRRRR on Abeta aggregation was examined in detail using laser light scattering, circular dichroism spectroscopy, Fourier transform infrared spectroscopy, thioflavin T fluorescence, and transmission electron microscopy. PMID:15952797

  13. Do particle size and surface functionality affect uptake and depuration of gold nanoparticles by aquatic invertebrates?

    PubMed

    Park, Sujung; Woodhall, James; Ma, Guibin; Veinot, Jonathan G C; Boxall, Alistair B A

    2015-04-01

    Because of the widespread use of engineered nanoparticles (ENPs) in consumer and industrial products, it is inevitable that these materials will enter the environment. It is often stated that the uptake of ENPs into organisms in the environment is related to the particle size and surface functionality. To test this assumption, the present study investigated the uptake and depuration of gold nanoparticle (Au NPs) coated with either citrate (Au-citrate NPs), mercaptoundecanoic acid (Au-MUDA NPs), amino polyethylene glycol (PEG) thiol (Au-NH2 NPs), or PEG (Au-PEG NP) by the aquatic invertebrate Gammarus pulex. The studies were performed using a range of standard ecotoxicity media and natural waters, resulting in varying degrees of aggregation of the different NPs. Uptake of gold by G. pulex varied depending on the surface coatings, with Au-MUDA and Au-citrate NPs being taken up to a greater extent than Au-NH2 and Au-PEG NPs in all test media and natural waters. In all test media evaluated, higher amounts of amino and PEG-coated ENPs were eliminated compared with MUDA- and citrate-coated ENPs. No obvious relationships were seen between the aggregation state of the different Au NPs in treatment and uptake, suggesting that the widely accepted assumption that Au NP uptake is related to particle size does not hold for the range of aggregation states studied (67.1-178.8?nm). Positive correlations between particle number concentration in the media and uptake were observed, indicating that this factor might partly explain the differences in uptake of a particle from different media types. Environ Toxicol Chem 2015;34:850-859. © 2014 SETAC. PMID:25556899

  14. Domains of surfactant protein A that affect protein oligomerization, lipid structure and surface tension.

    PubMed

    Palaniyar, N; Ikegami, M; Korfhagen, T; Whitsett, J; McCormack, F X

    2001-05-01

    Surfactant protein A (SP-A) is an abundant protein found in pulmonary surfactant which has been reported to have multiple functions. In this review, we focus on the structural importance of each domain of SP-A in the functions of protein oligomerization, the structural organization of lipids and the surface-active properties of surfactant, with an emphasis on ultrastructural analyses. The N-terminal domain of SP-A is required for disulfide-dependent protein oligomerization, and for binding and aggregation of phospholipids, but there is no evidence that this domain directly interacts with lipid membranes. The collagen-like domain is important for the stability and oligomerization of SP-A. It also contributes shape and dimension to the molecule, and appears to determine membrane spacing in lipid aggregates such as common myelin and tubular myelin. The neck domain of SP-A is primarily involved in protein trimerization, which is critical for many protein functions, but it does not appear to be directly involved in lipid interactions. The globular C-terminal domain of SP-A clearly plays a central role in lipid binding, and in more complex functions such as the formation and/or stabilization of curved membranes. In recent work, we have determined that the maintenance of low surface tension of surfactant in the presence of serum protein inhibitors requires cooperative interactions between the C-terminal and N-terminal domains of the molecule. This effect of SP-A requires a high degree of oligomeric assembly of the protein, and may be mediated by the activity of the protein to alter the form or physical state of surfactant lipid aggregates. PMID:11369537

  15. Autoimmune Disease-Associated Alleles Affect Histamine Receptor H1 Protein Trafficking and Cell Surface Expression

    PubMed Central

    Noubade, Rajkumar; Saligrama, Naresha; Spach, Karen; Rio, Roxana del; Blankenhorn, Elizabeth P.; Kantidakis, Theodoros; Milligan, Graeme; Rincon, Mercedes; Teuscher, Cory

    2008-01-01

    Structural polymorphisms (L263P, M313V and S331P) in the third intracellular loop of the murine histamine receptor H1 (H1R) are candidates for Bphs, a shared autoimmune disease locus in experimental allergic encephalomyelitis (EAE) and experimental allergic orchitis. The P-V-P haplotype is associated with increased disease susceptibility (H1RS) whereas the L-M-S haplotype is associated with less severe disease (H1RR). Here we show that selective reexpression of the H1RS allele in T cells fully complements EAE susceptibility and the production of disease associated cytokines while selective reexpression of the H1RR allele does not. Mechanistically, we show that the two H1R alleles exhibit differential cell surface expression and altered intracellular trafficking, with the H1RR allele being retained within the endoplasmic reticulum (ER). Moreover, we show that all three residues (L-M-S) comprising the H1RR haplotype are required for altered expression. These data are the first to demonstrate that structural polymorphisms influencing cell surface expression of a G-protein coupled receptor in T cells regulates immune functions and autoimmune disease susceptibility. This is an author-produced version of a manuscript accepted for publication in The Journal of Immunology (The JI). The American Association of Immunologists, Inc. (AAI), publisher of The JI, holds the copyright to this manuscript. This version of the manuscript has not yet been copyedited or subjected to editorial proofreading by The JI; hence, it may differ from the final version published in The JI (online and in print). AAI (The JI) is not liable for errors or omissions in this author-produced version of the manuscript or in any version derived from it by the U.S. National Institutes of Health or any other third party. The final, citable version of record can be found at www.jimmunol.org. PMID:18490747

  16. Dynamitin affects cell-surface expression of voltage-gated sodium channel Nav1.5.

    PubMed

    Chatin, Benoît; Colombier, Pauline; Gamblin, Anne Laure; Allouis, Marie; Le Bouffant, Françoise

    2014-11-01

    The major cardiac voltage-gated sodium channel Nav1.5 associates with proteins that regulate its biosynthesis, localization, activity and degradation. Identification of partner proteins is crucial for a better understanding of the channel regulation. Using a yeast two-hybrid screen, we identified dynamitin as a Nav1.5-interacting protein. Dynamitin is part of the microtubule-binding multiprotein complex dynactin. When overexpressed it is a potent inhibitor of dynein/kinesin-mediated transport along the microtubules by disrupting the dynactin complex and dissociating cargoes from microtubules. The use of deletion constructs showed that the C-terminal domain of dynamitin is essential for binding to the first intracellular interdomain of Nav1.5. Co-immunoprecipitation assays confirmed the association between Nav1.5 and dynamitin in mouse heart extracts. Immunostaining experiments showed that dynamitin and Nav1.5 co-localize at intercalated discs of mouse cardiomyocytes. The whole-cell patch-clamp technique was applied to test the functional link between Nav1.5 and dynamitin. Dynamitin overexpression in HEK-293 (human embryonic kidney 293) cells expressing Nav1.5 resulted in a decrease in sodium current density in the membrane with no modification of the channel-gating properties. Biotinylation experiments produced similar information with a reduction in Nav1.5 at the cell surface when dynactin-dependent transport was inhibited. The present study strongly suggests that dynamitin is involved in the regulation of Nav1.5 cell-surface density. PMID:25088759

  17. Meteor44 Video Meteor Photometry

    NASA Astrophysics Data System (ADS)

    Swift, Wesley R.; Suggs, Robert M.; Cooke, William J.

    2004-12-01

    Meteor44 is a software system developed at MSFC for the calibration and analysis of video meteor data. The photometric range of the (8 bit) video data is extended from a visual magnitude range of from 8 to 3 to from 8 to -8 for both meteors and stellar images using saturation compensation. Camera and lens specific saturation compensation coefficients are derived from artificial variable star laboratory measurements. Saturation compensation significantly increases the number of meteors with measured intensity and improves the estimation of meteoroid mass distribution. Astrometry is automated to determine each image's plate coefficient using appropriate star catalogs. The images are simultaneously intensity calibrated from the contained stars to determine the photon sensitivity and the saturation level referenced above the atmosphere. The camera's spectral response is used to compensate for stellar color index and typical meteor spectra in order to report meteor light curves in traditional visual magnitude units. Recent efforts include improved camera calibration procedures and long focal length "streak" meteor photometry. Meteor44 has been used to analyze data from the 2001, 2002 and 2003 MSFC Leonid observational campaigns as well as several lesser showers.

  18. Errors In Short Distance Photometry

    NASA Astrophysics Data System (ADS)

    Holmes, J. G.; Moermann, J. J. B.

    1982-02-01

    The errors involved in the short-distance photometry of projectors are evaluated and the same conclusions have been shown to apply to general purpose luminaires. The mathematical analysis from which the equations were derived has been published in Lighting Research and Technology (1981). The illuminance at a short distance from the projector does not follow the inverse square law; the errors depend on the angular subtense of the aperture of the projector relative to the divergence of the beam, and on the distribution of luminance across the aperture of the projector. At any particular distance, the errors are least in directions in which the curvature of the intensity distribution curve is least; the errors may therefore be greatest in the axial direction or in the direction of a shoulder on the curve, and they may change sign where the intensity distribution curve changes from convex to concave. In any particular direction, the error is greater if the outer zones of the projector have higher luminance or give a narrower relative spread; the worst case is a ring-shaped luminaire. If the relative error is less than 10 per cent, it is inversely proportional to the square of the distance of measurement. For general guidance, a nomogram relates the maximum likely percentage error to the beam divergence and to the relative distance of measurement; an empirical reference distance, to be known as the Beam Cross-over Distance, is suggested to replace the traditional 'cross-over distance' of a projector.

  19. Meteor44 Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Cooke, William J.

    2004-01-01

    Meteor44 is a software system developed at MSFC for the calibration and analysis of video meteor data. The dynamic range of the (8bit) video data is extended by approximately 4 magnitudes for both meteors and stellar images using saturation compensation. Camera and lens specific saturation compensation coefficients are derived from artificial variable star laboratory measurements. Saturation compensation significantly increases the number of meteors with measured intensity and improves the estimation of meteoroid mass distribution. Astrometry is automated to determine each image's plate coefficient using appropriate star catalogs. The images are simultaneously intensity calibrated from the contained stars to determine the photon sensitivity and the saturation level referenced above the atmosphere. The camera s spectral response is used to compensate for stellar color index and typical meteor spectra in order to report meteor light curves in traditional visual magnitude units. Recent efforts include improved camera calibration procedures, long focal length 'streak' meteor photometry and two-station track determination. Meteor44 has been used to analyze data from the 2001, 2002 and 2003 MSFC Leonid observational campaigns as well as several lesser showers. The software is interactive and can be demonstrated using data from recent Leonid campaigns.

  20. Proliferation of Purple Sulphur Bacteria at the Sediment Surface Affects Intertidal Mat Diversity and Functionality

    PubMed Central

    Hubas, Cédric; Jesus, Bruno; Ruivo, Mickael; Meziane, Tarik; Thiney, Najet; Davoult, Dominique; Spilmont, Nicolas; Paterson, David M.; Jeanthon, Christian

    2013-01-01

    There is a relative absence of studies dealing with mats of purple sulphur bacteria in the intertidal zone. These bacteria display an array of metabolic pathways that allow them to disperse and develop under a wide variety of conditions, making these mats important in terms of ecosystem processes and functions. Mass blooms of purple sulphur bacteria develop during summer on sediments in the intertidal zone especially on macroalgal deposits. The microbial composition of different types of mats differentially affected by the development of purple sulphur bacteria was examined, at low tide, using a set of biochemical markers (fatty acids, pigments) and composition was assessed against their influence on ecosystem functions (sediment cohesiveness, CO2 fixation). We demonstrated that proliferation of purple sulphur bacteria has a major impact on intertidal mats diversity and functions. Indeed, assemblages dominated by purple sulphur bacteria (Chromatiaceae) were efficient exopolymer producers and their biostabilisation potential was significant. In addition, the massive growth of purple sulphur bacteria resulted in a net CO2 degassing whereas diatom dominated biofilms represented a net CO2 sink. PMID:24340018

  1. Calibration of the MACHO Photometry Database

    E-print Network

    C. Alcock; R. A. Allsman; D. R. Alves; T. S. Axelrod; A. C. Becker; D. P. Bennett; K. H. Cook; A. J. Drake; K. C. Freeman; K. Griest; M. J. Lehner; S. L. Marshall; D. Minniti; B. A. Peterson; M. R. Pratt; C. A. Nelson; P. J. Quinn; C. W. Stubbs; W. Sutherland; A. B. Tomaney; D. L. Welch

    1999-09-14

    The MACHO Project is a microlensing survey that monitors the brightnesses of 60 million stars in the Large Magellanic Cloud (LMC), Small Magellanic Cloud, and Galactic bulge. Our database presently contains about 80 billion photometric measurements, a significant fraction of all astronomical photometry. We describe the calibration of MACHO two-color photometry and transformation to the standard Kron-Cousins V and R system. Calibrated MACHO photometry may be properly compared with all other observations on the Kron-Cousins standard system, enhancing the astrophysical value of these data. For 9 million stars in the LMC bar, independent photometric measurements of 20,000 stars with V photometry with published photometric sequences and new Hubble Space Telescope observations shows agreement. The current calibration zero-point uncertainty for the remainder of the MACHO photometry database is estimated to be +- 0.10 mag in V or R and +-0.04 mag in (V-R). We describe the first application of calibrated MACHO photometry data: the construction of a color-magnitude diagram used to calculate our experimental sensitivity to detect microlensing in the LMC.

  2. Regression analysis in modeling of air surface temperature and factors affecting its value in Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Rajab, Jasim Mohammed; Jafri, Mohd. Zubir Mat; Lim, Hwee San; Abdullah, Khiruddin

    2012-10-01

    This study encompasses air surface temperature (AST) modeling in the lower atmosphere. Data of four atmosphere pollutant gases (CO, O3, CH4, and H2O) dataset, retrieved from the National Aeronautics and Space Administration Atmospheric Infrared Sounder (AIRS), from 2003 to 2008 was employed to develop a model to predict AST value in the Malaysian peninsula using the multiple regression method. For the entire period, the pollutants were highly correlated (R=0.821) with predicted AST. Comparisons among five stations in 2009 showed close agreement between the predicted AST and the observed AST from AIRS, especially in the southwest monsoon (SWM) season, within 1.3 K, and for in situ data, within 1 to 2 K. The validation results of AST with AST from AIRS showed high correlation coefficient (R=0.845 to 0.918), indicating the model's efficiency and accuracy. Statistical analysis in terms of ? showed that H2O (0.565 to 1.746) tended to contribute significantly to high AST values during the northeast monsoon season. Generally, these results clearly indicate the advantage of using the satellite AIRS data and a correlation analysis study to investigate the impact of atmospheric greenhouse gases on AST over the Malaysian peninsula. A model was developed that is capable of retrieving the Malaysian peninsulan AST in all weather conditions, with total uncertainties ranging between 1 and 2 K.

  3. How does the spaceborne radar blind zone affect derived surface snowfall statistics in polar regions?

    NASA Astrophysics Data System (ADS)

    Maahn, Maximilian; Burgard, Clara; Crewell, Susanne; Gorodetskaya, Irina V.; Kneifel, Stefan; Lhermitte, Stef; Van Tricht, Kristof; Lipzig, Nicole P. M.

    2014-12-01

    Global statistics of snowfall are currently only available from the CloudSat satellite. But CloudSat cannot provide observations of clouds and precipitation within the so-called blind zone, which is caused by ground-clutter contamination of the CloudSat radar and covers the last 1200 m above land/ice surface. In this study, the impact of the blind zone of CloudSat on derived snowfall statistics in polar regions is investigated by analyzing three 12 month data sets recorded by ground-based Micro Rain Radar (MRR) at the Belgian Princess Elisabeth station in East Antarctica and at Ny-Ålesund and Longyearbyen in Svalbard, Norway. MRR radar reflectivity profiles are investigated in respect to vertical variability in the frequency distribution, changes in the number of observed snow events, and impacts on total precipitation. Results show that the blind zone leads to reflectivity being underestimated by up to 1 dB, the number of events being altered by ±5% and the precipitation amount being underestimated by 9 to 11 percentage points. Besides investigating a blind zone of 1200 m, the impacts of a reduced blind zone of 600 m are also analyzed. This analysis will help in assessing future missions with a smaller blind zone. The reduced blind zone leads to improved representation of mean reflectivity but does not improve the bias in event numbers and precipitation amount.

  4. Experiences with Opto-Mechanical Systems that Affect Optical Surfaces at the Sub-Nanometer Level

    SciTech Connect

    Hale, L C; Taylor, J S

    2008-04-03

    Projection optical systems built for Extreme Ultraviolet Lithography (EUVL) demonstrated the ability to produce, support and position reflective optical surfaces for achieving transmitted wavefront errors of 1 nm or less. Principal challenges included optical interferometry, optical manufacturing processes, multi-layer coating technology and opto mechanics. Our group was responsible for designing, building and aligning two different projection optical systems: a full-field, 0.1 NA, four-mirror system for 70 nm features and a small-field, 0.3 NA, two-mirror system for 30 nm features. Other than physical size and configuration, the two systems were very similar in the way they were designed, built and aligned. A key difference exists in the optic mounts, driven primarily by constraints from the metrology equipment used by different optics manufacturers. As mechanical stability and deterministic position control of optics will continue to play an essential role in future systems, we focus our discussion on opto-mechanics and primarily the optic mounts.

  5. Transglycosylated rutin-specific non-surface-active nanostructure affects absorption enhancement of flurbiprofen.

    PubMed

    Tozuka, Yuichi; Higashi, Kenjirou; Morita, Takeshi; Nishikawa, Masahiro; Uchiyama, Hiromasa; Zhang, Junying; Moribe, Kunikazu; Nishikawa, Keiko; Takeuchi, Hirofumi; Yamamoto, Keiji

    2012-09-01

    Transglycosylated rutin (Rutin-G), a newly developed transglycosylated food additive, was used as a novel excipient for improving the dissolution and absorption properties of flurbiprofen. No surface activity was found up to 100mg/mL of Rutin-G concentration. No cytotoxicity to Caco-2 cells was observed even at a high level of 100mg/mL Rutin-G solution. (1)H NMR study with concentration variation revealed that Rutin-G formed small aggregates in water, with the aggregation number of Rutin-G above the critical aggregation concentration of about 5.0mg/mL being 4. Structural analyses by small-angle X-ray scattering determined the aggregate to be several nanometers in maximum length. A solubility test of flurbiprofen in the presence of Rutin-G showed that the amount of dissolved flurbiprofen increased in proportion to the amount of Rutin-G loaded. This finding indicated a stoichiometric relationship between flurbiprofen and Rutin-G. The spray-dried particles of flurbiprofen/Rutin-G showed a significantly higher dissolution rate and greater absorption profile compared with the commercial flurbiprofen powder. Taken together, the results indicate the potential application of Rutin-G in the formation of a novel nanostructure of drug/transglycosylated material. PMID:22705643

  6. Subglacial drainage of surface melt water affects ice motion: Application of a modeling study to West Greenland

    NASA Astrophysics Data System (ADS)

    Chu, W.; Creyts, T. T.; Bell, R. E.

    2013-12-01

    Subglacial hydrology is one of the main controlling factors in the spatial and temporal evolution of ice flow. The distribution of effective pressure and the form of subglacial drainage networks have important implications on basal sliding. However, subglacial melt water drainage is dynamic in space and time and varies in a complicated manner coupled to surface hydrology. Despite recent conceptual advances, relatively little is known about how the surface hydrology interacts with the subglacial drainage system and how it affects effective pressure and ice flow. Here, we build a 2D numerical model of subglacial drainage to investigate the coupling between drainage of surface melt water and glacier motion. A synthetic glacier geometry is used to obtain the steady-state solutions for effective pressure and subglacial conduit sizes on a rectangular grid. The model has channels and distributed linked cavities that occupy the grid centers and exchange water along the grid edges. The numerical procedure uses Newton's method to compute water pressure and conduit cross-sectional area. The water pressure solution is applied to a sliding law to calculate ice flow speed. We then applied the water model to a 6000 km2 catchment south of Jakobshavn Isbrae along the western margin of Greenland. The water model is forced with surface melt input from the Polar MM5 regional climate model. Surface melt is supplied at discrete locations through supraglacial lakes. The location of supraglacial lakes are identified from satellite imagery. We compare modeled output of ice speed to satellite derived measurements of ice flow and discuss their agreements and discrepancies.

  7. Optical properties of boreal forest fire smoke derived from Sun photometry

    Microsoft Academic Search

    N. T. O'Neill; T. F. Eck; B. N. Holben; A. Smirnov; A. Royer; Z. Li

    2002-01-01

    Aerosol optical properties derived from Sun photometry were investigated in terms of climatological trends at two Sun photometer sites significantly affected by western Canadian boreal forest fire smoke and in terms of a 2-week series of smoke events observed at stations near and distant from boreal forest fires. Aerosol optical depth (taua) statistics for Waskesiu, Saskatchewan, and Thompson, Manitoba, were

  8. Eos, Koronis, and Maria Family Asteroids: Infrared (JHK) Photometry

    NASA Technical Reports Server (NTRS)

    Veeder, Glenn J.; Matson, Dennis L.; Owensby, Pamela D.; Gradie, Jonathan C.; Bell, Jeffrey F.; Tedesco, Edward F.

    1995-01-01

    Infrared photometry at 1.2, 1.6, and 2.2 micrometer (JHK) is reported for 56 asteroids in the Eos, Koronis and, Maria dynamical families. These data are consistent with similar surface composition for all of the asteroids of each family. The infrared colors within each family cluster in the region observed for the S taxonomic class, but Eos asteroids may belong to a separable K class. Asteroid 243 Ida, which was observed by the Galileo spacecraft, is a typical member of the Koronis family. The average infrared colors of the Maria family are slightly redder than those of the Eos and Koronis families.

  9. Coating thickness affects surface stress measurement of brush electro-plating nickel coating using Rayleigh wave approach.

    PubMed

    Liu, Bin; Dong, Shiyun; Xu, Binshi; He, Peng

    2012-09-01

    A surface ultrasonic wave approach was presented for measuring surface stress of brush electro-plating nickel coating specimen, and the influence of coating thickness on surface stress measurement was discussed. In this research, two Rayleigh wave transducers with 5MHz frequency were employed to collect Rayleigh wave signals of coating specimen with different static tensile stresses and different coating thickness. The difference in time of flight between two Rayleigh wave signals was determined based on normalized cross correlation function. The influence of stress on propagation velocity of Rayleigh wave and the relationship between the difference in time of flight and tensile stress that corresponded to different coating thickness were discussed. Results indicate that inhomogeneous deformation of coating affects the relationship between the difference in time of flight and tensile stress, velocity of Rayleigh wave propagating in coating specimen increases with coating thickness increasing, and the variation rate reduces of difference in time of flight with tensile stress increasing as coating thickness increases. PMID:22534060

  10. Longtime monitoring of groundwater levels and matric potentials in organic and inorganic soils affected by surface drainage and groundwater extraction

    NASA Astrophysics Data System (ADS)

    Zimmermann, Iris; Fleige, Heiner; Horn, Rainer

    2014-05-01

    Drainage of organic soils leads to severe degradation of the soil matrix due to shrinkage, oxidation and development of hydrophobicity. Also, grassland vegetation on cultivated peatland soils is adapted to water supply through capillary rise from the groundwater to guarantee good yields. Monitoring of groundwater levels and soil matric potentials was performed in a period of ten years (2003-2013) at six investigation sites in a plain tract surrounded by Saalean deposits in south-west Schleswig-Holstein, Germany. The area is under agricultural use; all monitoring sites are under grassland. The groundwater situation in the area has been strongly affected by surface drainage (since 1969) and groundwater extraction for industrial and private utilization (since 1977). Soil physical measurements on soil samples taken from six soil profiles in the investigation area (2003) showed an advanced degradation of the organic soil horizons as a result of the dewatering. Furthermore, in 2003 drainage and groundwater extraction resulted in a situation, where water supply in the root zone via capillary rise from the groundwater was no longer guaranteed on some of the investigation sites, leading to yield depressions in dry periods as the vegetation was dependent on precipitation events for water supply. In 2006 new regulations of the groundwater extraction lead to a continuously rise of the groundwater level, indicating an interaction between the surface aquifer and the deep aquifer where the groundwater was extracted, as the surface drainage management remained unchanged. Correlations between the extraction rate of the groundwater wells in the investigation area and the groundwater level in the surface aquifer were found.

  11. Spatio-temporal patterns in land use and management affecting surface runoff response of agricultural catchments—A review

    NASA Astrophysics Data System (ADS)

    Fiener, P.; Auerswald, K.; Van Oost, K.

    2011-05-01

    Surface runoff and associated erosion processes adversely affect soil and surface water quality. There is increasing evidence that a sound understanding of spatial-temporal dynamics of land use and management are crucial to understanding surface runoff processes and underpinning mitigation strategies. In this review, we synthesise the effects of (1) temporal patterns of land management of individual fields, and (2) spatio-temporal interaction of several fields within catchments by applying semivariance analysis, which allows the extent and range of the different patterns to be compared. Consistent effects of management on the temporal dynamics of surface runoff of individual fields can be identified, some of which have been incorporated into small-scale hydrological models. In contrast, the effects of patchiness, the spatial organisation of patches with different soil hydrological properties, and the effects of linear landscape structures are less well understood and are rarely incorporated in models. The main challenge for quantifying these effects arises from temporal changes within individual patches, where the largest contrasts usually occur in mid-summer and cause a seasonally varying effect of patchiness on the overall catchment response. Some studies indicate that increasing agricultural patchiness, due to decreasing field sizes, reduces the catchment-scale response to rainfall, especially in cases of Hortonian runoff. Linear structures associated with patchiness of fields (e.g. field borders, ditches, and ephemeral gullies) may either increase or decrease the hydraulic connectivity within a catchment. The largest gap in research relates to the effects and temporal variation of patch interaction, the influence of the spatial organisation of patches and the interaction with linear structures. In view of the substantial changes in the structure of agricultural landscapes occurring throughout the world, it is necessary to improve our knowledge of the influence of patchiness and connectivity, and to implement this knowledge in new modelling tools.

  12. Gaia photometry for white dwarfs

    NASA Astrophysics Data System (ADS)

    Carrasco, J. M.; Catalán, S.; Jordi, C.; Tremblay, P.-E.; Napiwotzki, R.; Luri, X.; Robin, A. C.; Kowalski, P. M.

    2014-05-01

    Context. White dwarfs can be used to study the structure and evolution of the Galaxy by analysing their luminosity function and initial mass function. Among them, the very cool white dwarfs provide the information for the early ages of each population. Because white dwarfs are intrinsically faint only the nearby (~ 20 pc) sample is reasonably complete. The Gaia space mission will drastically increase the sample of known white dwarfs through its 5-6 years survey of the whole sky up to magnitude V = 20-25. Aims: We provide a characterisation of Gaia photometry for white dwarfs to better prepare for the analysis of the scientific output of the mission. Transformations between some of the most common photometric systems and Gaia passbands are derived. We also give estimates of the number of white dwarfs of the different galactic populations that will be observed. Methods: Using synthetic spectral energy distributions and the most recent Gaia transmission curves, we computed colours of three different types of white dwarfs (pure hydrogen, pure helium, and mixed composition with H/He = 0.1). With these colours we derived transformations to other common photometric systems (Johnson-Cousins, Sloan Digital Sky Survey, and 2MASS). We also present numbers of white dwarfs predicted to be observed by Gaia. Results: We provide relationships and colour-colour diagrams among different photometric systems to allow the prediction and/or study of the Gaia white dwarf colours. We also include estimates of the number of sources expected in every galactic population and with a maximum parallax error. Gaia will increase the sample of known white dwarfs tenfold to about 200 000. Gaia will be able to observe thousands of very cool white dwarfs for the first time, which will greatly improve our understanding of these stars and early phases of star formation in our Galaxy. Tables 6 and 7 are available in electronic form at http://www.aanda.orgFull Tables 3-5 are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/565/A11

  13. Detection of Terrestrial Planets Using Transit Photometry

    NASA Technical Reports Server (NTRS)

    Koch, David; Witteborn, Fred; Jenkins, Jon; Dunham, Edward; Boruci, William; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Transit photometry detection of planets offers many advantages: an ability to detect terrestrial size planets, direct determination of the planet's size, applicability to all main-sequence stars, and a differential brightness change of the periodic signature being independent of stellar distance or planetary orbital semi-major axis. Ground and space based photometry have already been successful in detecting transits of the giant planet HD209458b. However, photometry 100 times better is required to detect terrestrial planets. We present results of laboratory measurements of an end-to-end photometric system incorporating all of the important confounding noise features of both the sky and a space based photometer including spacecraft jitter. In addition to demonstrating an instrumental noise of less than 10 ppm (an Earth transit of a solar-like star is 80 ppm), the brightnesses of individual stars were dimmed to simulate Earth-size transit signals. These 'transits' were reliably detected as part of the tests.

  14. Principles and scope of synthetic photometry

    NASA Technical Reports Server (NTRS)

    Buser, R.

    1986-01-01

    The synthetic photometry algorithm and various applications for the algorithm are described. The synthetic photometry algorithm provides magnitudes and colors computed from a spectral energy flux distribution and the response functions of a photometric system. The principles of synthetic photometry which include the observed and theoretical stellar energy distributions and passbands of the photometric systems are discussed. The equations utilized in the algorithm to compute the magnitudes and color indices are provided. There is a need for an evaluation of the passbands and a correlation between the observed photometric and spectrophotometric data of the stars. The algorithm is used as a universal translator providing the communication channels between different reseach areas; it is applicable to clusters, faint star counts, and deep multicolor surveys of galaxies.

  15. Photographic stellar photometry with the PDS microdensitometer

    NASA Technical Reports Server (NTRS)

    Stetson, P. B.

    1979-01-01

    A technique for photographic stellar photometry with the PDS microdensitometer is described. It employs a least-squares fit to a model density profile to derive an instrumental magnitude index, an image-abnormality index, and the local value of the background density for each image. The instrumental magnitude index is calibrated in terms of true magnitude by the same methods as for iris photometry. A preliminary test of the method using plates of the open cluster NGC 188 indicates that a precision comparable to or slightly better than that of conventional iris photometry or other methods of PDS reduction may easily be attained. Possibilities for the future elaboration of the technique are mentioned.

  16. INTEGRATED-LIGHT TWO MICRON ALL SKY SURVEY INFRARED PHOTOMETRY OF GALACTIC GLOBULAR CLUSTERS

    E-print Network

    Metchev, Stanimir

    INTEGRATED-LIGHT TWO MICRON ALL SKY SURVEY INFRARED PHOTOMETRY OF GALACTIC GLOBULAR CLUSTERS Judith surface brightness profiles in J, H, and Ks for 104 Galactic globular clusters. We fit these with King Ã? Ks, J Ã? H, and J Ã? Ks for these globular clusters. Each color shows a reasonably tight relation

  17. Time-resolved photometry of cataclysmic variables

    E-print Network

    C. Papadaki; H. M. J. Boffin; J. Cuypers; V. Stanishev; Z. Kraicheva; V. Genkov

    2003-12-18

    We present time-resolved photometry of two cataclysmic variables whose CCD photometric observations were obtained with the 1m telescope at the South African Astronomical Observatory in October 2002 and August 2003 and with the 1m telescope at Hoher List in Germany. Concerning MCT 2347-3144 we detect for the first time a period of 6.65h. For V1193 Ori the 3.96 h periodicity has for the first time been confirmed through time-resolved photometry.

  18. Extrasolar planet transit photometry at Wallace Astrophysical Observatory

    E-print Network

    Fong, Wen-fai

    2008-01-01

    Extrasolar planet transit photometry is a relatively new astronomical technique developed over the past decade. Transit photometry is the measurement of a star's brightness as an orbiting planet passes in front of the star ...

  19. NIST Photometry Short Course September 27-30, 2011

    E-print Network

    Perkins, Richard A.

    NIST Photometry Short Course September 27-30, 2011 100 Bureau Drive, Gaithersburg, MD 20899 Bldg.00 ) Registrant Information gfedc gfedc Page 1 of 3NIST Conference Registration 6/29/2011file://Z:\\My Documents\\FORMS\\photometry

  20. Time Series Photometry Data: Standard Access, Standard Formats

    E-print Network

    Holl, András

    Time Series Photometry Data: Standard Access, Standard Formats Andr#19; as Holl Konkoly Observatory a discussion on data access and #12;le format aspects of photometry. Introduction Presently there is time series photometry data available in public databases, but the access to these varies from one collection

  1. Instrument Science Report ACS 2006-01 PSFs, Photometry,

    E-print Network

    Sirianni, Marco

    Instrument Science Report ACS 2006-01 PSFs, Photometry, and Astrometry for the ACS/WFC Jay Anderson is to be interpolated for each star. Fitting these PSFs to star images gives photometry and astrometry with accuracies hurting photometry. The following sections present our modeling of the F606W PSF, and also provide PSFs

  2. Uranium in Surface Waters and Sediments Affected by Historical Mining in the Denver West 1:100,000 Quadrangle, Colorado

    USGS Publications Warehouse

    Zielinski, Robert A.; Otton, James K.; Schumann, R. Randall; Wirt, Laurie

    2008-01-01

    Geochemical sampling of 82 stream waters and 87 stream sediments within mountainous areas immediately west of Denver, Colorado, was conducted by the U.S. Geological Survey in October 1994. The primary purpose was to evaluate regionally the effects of geology and past mining on the concentration and distribution of uranium. The study area contains uranium- and thorium-rich bedrock, numerous noneconomic occurrences of uranium minerals, and several uranium deposits of variable size and production history. During the sampling period, local streams had low discharge and were more susceptible to uranium-bearing acid drainage originating from historical mines of base- and precious-metal sulfides. Results indicated that the spatial distribution of Precambrian granites and metamorphic rocks strongly influences the concentration of uranium in stream sediments. Within-stream transport increases the dispersion of uranium- and thorium rich mineral grains derived primarily from granitic source rocks. Dissolved uranium occurs predominantly as uranyl carbonate complexes, and concentrations ranged from less than 1 to 65 micrograms per liter. Most values were less than 5 micrograms per liter, which is less than the current drinking water standard of 30 micrograms per liter and much less than locally applied aquatic-life toxicity standards of several hundred micrograms per liter. In local streams that are affected by uranium-bearing acid mine drainage, dissolved uranium is moderated by dilution and sorptive uptake by stream sediments. Sorbents include mineral alteration products and chemical precipitates of iron- and aluminum-oxyhydroxides, which form where acid drainage enters streams and is neutralized. Suspended uranium is relatively abundant in some stream segments affected by nearby acid drainage, which likely represents mobilization of these chemical precipitates. The 234U/238U activity ratio of acid drainage (0.95-1.0) is distinct from that of local surface waters (more than 1.05), and this distinctive isotopic composition may be preserved in iron-oxyhydroxide precipitates of acid drainage origin. The study area includes a particularly large vein-type uranium deposit (Schwartzwalder mine) with past uranium production. Stream water and sediment collected downstream from the mine's surface operations have locally anomalous concentrations of uranium. Fine-grained sediments downstream from the mine contain rare minute particles (10-20 micrometers) of uraninite, which is unstable in a stream environment and thus probably of recent origin related to mining. Additional rare particles of very fine grained (less than 5 micrometer) barite likely entered the stream as discharge from settling ponds in which barite precipitation was formerly used to scavenge dissolved radium from mine effluent.

  3. Photometry of galaxies in compact groups

    SciTech Connect

    Tikhonov, N.A.

    1988-03-01

    The results are given of photographic photometry of galaxies in compact groups. The luminosity function of the galaxies in the investigated groups is similar to the luminosity function of field galaxies, open groups, and clusters. Of 54 groups, signs of merging of galaxies are observed in only one group.

  4. Photometry from online Digitized Sky Survey Plates

    E-print Network

    A. Bacher; S. Kimeswenger; P. Teutsch

    2005-07-22

    Online Digital Sky Survey (DSS) material is often used to obtain information on newly discovered variable stars for older epochs (e.g. Nova progenitors, flare stars, ...). We present here the results of an investigation of photometry on online digital sky survey material in small fields calibrated by CCD sequences. We compared different source extraction mechanisms and found, that even down near to the sensitivity limit, despite the H-compression used for the online material, photometry with an accuracy better than 0\\fm1 rms is possible on DSS-II. Our investigation shows that the accuracy depends strongly on the source extraction method. The SuperCOSMOS scans, although retrieved with an higher spatial resolution, do not give us better results. The methods and parameters presented here, allow the user to obtain good plate photometry in small fields down to the Schmidt plate survey limits with a few bright CCD calibrators, which may be calibrated with amateur size telescopes. Especially for the events mentioned above, new field photometry for calibration purposes mostly exists, but the progenitors were not measured photometrically before. Also the follow up whether stellar concentrations are newly detected clusters or similar work may be done without using mid size telescopes. The calibration presented here is a "local" one for small fields. We show that this method presented here gives higher accuracies than "global" calibrations of surveys (e.g. GSC-II, SuperCOSMOS and USNO-B)

  5. Diffraction Losses in Radiometry and Photometry

    Microsoft Academic Search

    W R Blevin

    1970-01-01

    The precision of radiometry and photometry is reaching a stage, in standardizing laboratories at least, where greater attention should be paid to losses of flux by diffraction. Otherwise errors of up to 0.5% or more may occur. This article reviews from the radiometric point of view diffraction losses at circular apertures, for both the Fraunhofer and Fresnel conditions and for

  6. Near-Field Photometry: A New Approach

    Microsoft Academic Search

    Ian Ashdown

    1992-01-01

    This paper presents a new approach to near-field photometry and describes a novel nearfieldgoniophotometer and illuminance calculation method. The approach is based onhelios, which is a rationalization of the luminance concept for volume sources. Thegoniophotometer measures the three-dimensional vector field of light surrounding aluminaire rather than any of its intrinsic properties. The calculation method can predictthe illuminance at any point

  7. CCD photometry of asteroid 932 Hooveria

    NASA Astrophysics Data System (ADS)

    Sada, Pedro V.

    2004-03-01

    CCD photometry of asteroid 932 Hooveria taken during October 2001 and January 2002 at the Universidad de Monterrey Observatory is reported. A synodic rotation period of either 29.947 or 30.370 hours is determined from eight nights of observations.

  8. Wise Observatory System of Fast CCD Photometry

    NASA Astrophysics Data System (ADS)

    Leibowitz, E. M.; Ibbetson, P.; Ofek, E. O.

    We have developed a data acquisition and an online reduction system for fast (a few seconds integration time) photometry with the Wise Observatory CCD camera. The method is based on successively collecting frames, each one is a mere small fraction of the entire CCD array. If necessary, the observer is able to place the object star and the comparison star on one and the same row or column of the CCD chip by rotating the image plane, an option available with the Wise telescope. In so doing, the rectangular frame that has to be read out may have a small area of only some 30 columns or rows, even when the two stars are far away from each other. The readout time of the small frame is thus reduced to merely one or two seconds. Thus photometry with an integration time of 5 s and up becomes possible. The system is a network of 3 computers. One controls the telescope, second controls the camera whilst the third computer is used, during the exposure of each frame, for data reduction of the previous one in the observing sequence. The online photometry is performed using standard procedures of the IRAF CCD photometry package. It yields an instrumental magnitude of the object star relative to one or more reference stars that are present in the frame. The light curve of the object star is displayed with a delay of a single frame relative to the one currently under acquisition.

  9. International Studies of Hazardous Groundwater/Surface Water Exchange in the Volcanic Eruption and Tsunami Affected Areas of Kamchatka

    NASA Astrophysics Data System (ADS)

    Kontar, Y. A.; Gusiakov, V. K.; Izbekov, P. E.; Gordeev, E.; Titov, V. V.; Verstraeten, I. M.; Pinegina, T. K.; Tsadikovsky, E. I.; Heilweil, V. M.; Gingerich, S. B.

    2012-12-01

    During the US-Russia Geohazards Workshop held July 17-19, 2012 in Moscow, Russia the international research effort was asked to identify cooperative actions for disaster risk reduction, focusing on extreme geophysical events. As a part of this recommendation the PIRE project was developed to understand, quantify, forecast and protect the coastal zone aquifers and inland water resources of Kamchatka (Russia) and its ecosystems affected by the November 4, 1952 Kamchatka tsunami (Khalatyrka Beach near Petropavlovsk-Kamchatskiy) and the January 2, 1996 Karymskiy volcano eruption and the lake tsunami. This project brings together teams from U.S. universities and research institutions located in Russia. The research consortium was briefed on recent technical developments and will utilize samples secured via major international volcanic and tsunami programs for the purpose of advancing the study of submarine groundwater discharge (SGD) in the volcanic eruption and tsunami affected coastal areas and inland lakes of Kamchatka. We plan to accomplish this project by developing and applying the next generation of field sampling, remote sensing, laboratory techniques and mathematical tools to study groundwater-surface water interaction processes and SGD. We will develop a field and modeling approach to define SGD environment, key controls, and influence of volcano eruption and tsunami, which will provide a framework for making recommendations to combat contamination. This is valuable for politicians, water resource managers and decision-makers and for the volcano eruption and tsunami affected region water supply and water quality of Kamchatka. Data mining and results of our field work will be compiled for spatial modeling by Geo-Information System (GIS) using 3-D Earth Systems Visualization Lab. The field and model results will be communicated to interested stakeholders via an interactive web site. This will allow computation of SGD spatial patterns. In addition, thanks to the conceptual integrated approach, the mathematical tool will be transportable to other regions affected by volcanic eruption and tsunami. We will involve students in the work, incorporate the results into our teaching portfolio and work closely with the IUGG GeoRisk Commission and AGU Natural Hazards Focus Group to communicate our findings to the broader public, specifically local communities that will be most impacted. Under the PIRE education component, a cohort of U.S. and Russian post-doctoral researchers and students will receive training and contribute to the overall natural hazards SGD science agenda in cooperation with senior U.S. researchers and leading investigators from the Russian institutions. Overall, the extensive team of researchers, students and institutions is poised to deliver an innovative and broad spectrum of science associated with the study of SGD in the volcanic eruption and tsunami affected areas, in a way not possible to achieve in isolation.

  10. High-Precision Photometry of Extreme KBO 2003 EL61

    NASA Astrophysics Data System (ADS)

    Lacerda, Pedro; Jewitt, David; Peixinho, Nuno

    2008-05-01

    We present high-precision, time-resolved, visible and near-infrared photometry of the large (diameter ~ 2500 km) Kuiper belt object (136108) 2003 EL61. The new data confirm rapid rotation at period P = 3.9155 ± 0.0001 h with a peak-to-peak photometric range of ?mR = 0.29 ± 0.02 mag and further show subtle but reproducible color variations with rotation. Rotational deformation of 2003 EL61 alone would give rise to a symmetric light curve free of color variations. The observed photometric deviations from the best-fit equilibrium model show the existence of a large surface region with an albedo and color different from the mean surface of 2003 EL61. We explore constraints on the nature of this anomalous region set by the existing data.

  11. The topography of microstructured surfaces differently affects fibrillin deposition by blood and lymphatic endothelial cells in culture.

    PubMed

    Rossi, Antonella; Pasqui, Daniela; Barbucci, Rolando; Gerli, Renato; Weber, Elisabetta

    2009-03-01

    While tissue-engineered blood vessels have already been successfully used in surgical practice, artificially restoring lymphatic circulation when needed is still far to be realized. Stability of arterial vessel wall depends on proper fibrillin deposition; fibrillin in fact is the scaffold for elastic fiber formation. In lymphatic vessels fibrillin is probably implied in lymph formation in response to interstitial requirements. This study was designed to verify whether fibrillin deposition is influenced by the topography of the substrate on which blood and lymphatic endothelial cells grow. Blood and lymphatic endothelial cells were cultured on microstructured surfaces with different topography: stripes of different widths (25, 50, and 100 microm), squares and rectangles, and spiral geometry, obtained by the photoimmobilization of Hyaluronan (Hyal) on aminosilanized glass. Cell orientation and fibrillin deposition were influenced by the topography of the microstructure. Blood endothelial cells deposited fibrillin as a bundle running parallel to the major axis of stripes and spirals, whereas the irregular network of fibrillin deposited by lymphatic endothelial cells was affected by the topography of the substrate only in the smallest stripes. These data bring a contribution to the basic knowledge required to design tissue-engineered blood and lymphatic vessels capable of adapting to the functional requirements of the surrounding environment. PMID:18759668

  12. Does the temperature of beverages affect the surface roughness, hardness, and color stability of a composite resin?

    PubMed Central

    Tuncer, Duygu; Karaman, Emel; Firat, Esra

    2013-01-01

    Objective: To investigate the effect of beverages’ temperature on the surface roughness, hardness, and color stability of a composite resin. Materials and Methods: Fifty specimens of the Filtek Z250 composite (3M ESPE, Dental Products, St.Paul, MN, USA) were prepared and initial roughness, microhardness, and color were measured. Then the specimens were randomly divided into five groups of 10 specimens each: Coffee at 70°C, coffee at 37°C, cola at 10°C, cola at 37°C, and artificial saliva (control). After the samples were subjected to 15 min × 3 cycles per day of exposure to the solutions for 30 days, the final measurements were recorded. Results: After immersion in beverages, the artificial saliva group showed hardness values higher than those of the other groups (P < 0.001) and the microhardness values were significantly different from the initial values in all groups except for the control group. Both cola groups showed roughness values higher than the baseline values (P < 0.05), while the other groups showed values similar to the baseline measurements. When ?E measurements were examined, the 70°C coffee group showed the highest color change among all the groups (P < 0.05). Conclusion: High-temperature solutions caused alterations in certain properties of composites, such as increased color change, although they did not affect the hardness or roughness of the composite resin material tested. PMID:24883021

  13. How do Atmospheres Affect Planetary Temperatures? Activity C Can we Model an Atmosphere's Effect Upon a Planet's Surface Temperature?

    NSDL National Science Digital Library

    In this activity, students simulate the interaction of variables, including carbon dioxide, in a radiation balance exercise using a spreadsheet-based radiation balance model. Through a series of experiments, students attempt to mimic the surface temperatures of Earth, Mercury, Venus and Mars, and account for the influence of greenhouse gases in atmospheric temperatures. The activity supports inquiry into the real-world problem of contemporary climate change. Student-collected data is needed from activity A in the same module, "How do atmospheres interact with solar energy?" to complete this activity. Included in the resource are several student data sheets and a teacher's guide. This activity is part of module 4, "How do Atmospheres Affect Planetary Temperatures?" in Earth Climate Course: What Determines a Planet's Climate? The course aims to help students to develop an understanding of our environment as a system of human and natural processes that result in changes that occur over various space and time scales.

  14. From Spitzer Galaxy photometry to Tully-Fisher distances

    NASA Astrophysics Data System (ADS)

    Sorce, J. G.; Tully, R. B.; Courtois, H. M.; Jarrett, T. H.; Neill, J. D.; Shaya, E. J.

    2014-10-01

    This paper involves a data release of the observational campaign: Cosmicflows with Spitzer (CFS). Surface photometry of the 1270 galaxies constituting the survey is presented. An additional ˜400 galaxies from various other Spitzer surveys are also analysed. CFS complements the Spitzer Survey of Stellar Structure in Galaxies, that provides photometry for an additional 2352 galaxies, by extending observations to low galactic latitudes (|b| < 30°). Among these galaxies are calibrators, selected in the K band, of the Tully-Fisher relation. The addition of new calibrators demonstrates the robustness of the previously released calibration. Our estimate of the Hubble constant using supernova host galaxies is unchanged, H0 = 75.2 ± 3.3 km s-1 Mpc-1. Distance-derived radial peculiar velocities, for the 1935 galaxies with all the available parameters, will be incorporated into a new data release of the Cosmicflows project. The size of the previous catalogue will be increased by 20 per cent, including spatial regions close to the Zone of Avoidance.

  15. Galileo Photometry of Asteroid 951 Gaspra

    USGS Publications Warehouse

    Helfenstein, P.; Veverka, J.; Thomas, P.C.; Simonelli, D.P.; Lee, P.; Klaasen, K.; Johnson, T.V.; Breneman, H.; Head, J.W.; Murchie, S.; Fanale, F.; Robinson, M.; Clark, B.; Granahan, J.; Garbeil, H.; McEwen, A.S.; Kirk, R.L.; Davies, M.; Neukum, G.; Mottola, S.; Wagner, R.; Belton, M.; Chapman, C.; Pilcher, C.

    1994-01-01

    Galileo images of Gaspra make it possible for the first time to determine a main-belt asteroid's photometric properties accurately by providing surface-resolved coverage over a wide range of incidence and emission angles and by extending the phase angle coverage to phases not observable from Earth. We combine Earth-based telescopic photometry over phase angles 2?? ??? ?? ??? 25?? with Galileo whole-disk and disk-resolved data at 33?? ??? ?? ??? 51?? to derive average global photometric properties in terms of Hapke's photometric model. The microscopic texture and particle phase-function behavior of Gaspra's surface are remarkably like those of other airless rocky bodies such as the Moon. The macroscopic surface roughness parameter, ??? = 29??, is slightly larger than that reported for typical lunar materials. The particle single scattering albedo, ???0 = 0.36 ?? 0.07, is significantly larger than for lunar materials, and the opposition surge amplitude, B0 = 1.63 ?? 0.07, is correspondingly smaller. We determine a visual geometric albedo pv = 0.22 ?? 0.06 for Gaspra, in close agreement with pv = 0.22 ?? 0.03 estimated from Earth-based observations. Gaspra's phase integral is 0.47, and the bolometric Bond albedo is estimated to be 0.12 ?? 0.03. An albedo map derived by correcting Galileo images with our average global photometric function reveals subdued albedo contrasts of ??10% or less over Gaspra's northern hemisphere. Several independent classification algorithms confirm the subtle spectral heterogeneity reported earlier (S. Mottola, M. DiMartino, M. Gonano-Beurer, H. Hoffman, and G. Neukum, 1993, Asteroids, Comets, Meteors, pp. 421-424; M. J. S. Belton et al., 1992, Science 257, 1647-1652). Whole-disk colors (0.41 ??? ?? ??? 0.99 ??m) vary systematically with longitude by about ??5%, but color differences as large as 30% occur locally. Colors vary continuously between end-member materials whose areal distribution correlates with regional topography. Infrared: violet (0.99:0.41-??m) color ratios on Gaspra are strongly correlated with local elevation, being largest at lower elevations and smaller at higher elevations. No correlation was detected between elevation and the green:violet (0.56:0.41-??m) color ratio. Bright materials with a strong 1-??m absorption occur primarily in association with craters along ridges, while darker materials with 30% weaker 1-??m signatures occur downslope. The variations of color and albedo cannot be easily explained by grain-size effects alone or by differences in photometric geometry. The trends observed are consistent with those revealed by laboratory studies of the effects of comminution, glass formation, and segregation of metal from silicate components in chondritic meteorites and also in some silicate mixtures. The relative importance of these various processes on Gaspra remains to be determined. ?? 1994 Academic Press. All rights reserved.

  16. Recalibrating SFD Using SDSS Spectroscopy And Photometry

    NASA Astrophysics Data System (ADS)

    Schlafly, Eddie; Finkbeiner, D. P.

    2011-05-01

    We use new measurements of reddening using SDSS photometry and spectroscopy to test the SFD dust map. We find that both the photometric and spectroscopic technique agree on a common SFD calibration that is different from the original SFD calibration by 13%. We find additionally that a Fitzpatrick 1999 reddening law provides a good fit to the reddening law derived from these techniques, while CCM and O'Donnell reddening laws are disfavored.

  17. Lightcurve Photometry Opportunities: 2015 April-June

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Harris, Alan W.; Durech, Josef; Benner, Lance A. M.

    2015-04-01

    We present lists of asteroid photometry opportunities for objects reaching a favorable apparition and having either none or poorly-defined lightcurve parameters. Additional data on these objects will help with shape and spin axis modeling via lightcurve inversion. We also include lists of objects that will be the target of radar observations. Lightcurves for these objects can help constrain pole solutions and/or remove rotation period ambiguities that might not come from using radar data alone.

  18. Fattening pig performance as affected by the number of pigs per pen, the bedded surface area and the available volume per pig in fattening houses

    E-print Network

    Paris-Sud XI, Université de

    Fattening pig performance as affected by the number of pigs per pen, the bedded surface area been elucidated : How many pigs per pen ? How large the area and useful volume per pig ? How many pigs per house ? Is it possible to cram the fattening pens'? A total of 12 trials were made by the I

  19. THE SIZE AND SURFACE COATING OF NANOSILVER DIFFERENTIALLY AFFECTS BIOLOGICAL ACTIVITY IN BLOOD BRAIN BARRIER (RBEC4) CELLS.

    EPA Science Inventory

    Linking the physical properties of nanoparticles with differences in their biological activity is critical for understanding their potential toxicity and mode of action. The influence of aggregate size, surface coating, and surface charge on nanosilver's (nanoAg) movement through...

  20. Coordinated Ultraviolet Spectroscopy and Optical Photometry of FK Comae

    NASA Astrophysics Data System (ADS)

    Guinan, Edward F.

    FK Comae (HD 117555) is the prototype of a newly identified class of rapidly rotating, apparently single, cool giants which have strong chromospheric and coronal emission rivalling or surpassing those of the most active RS CVn stars. FK Com is the best studied member of the group. It has spectral type about G2 IIIp, a projected rotational velocity v sin i =120 km/s, and is a low amplitude variable with a 2.4d period. Photometry by Dorren, Guinan and McCook in 1982 shows for the first time that the light curve undergoes rapid changes in amplitude, shape, and phase of light minimum. Such behavior is known for the RS CVn stars, but is generally on longer timescales. Analyses of the 1982 light curves have been carried out and show that the light variations appear to be consistent with subluminous regions ("starspots") on the surface of the rapidly rotating giant. The overall spectroscopic and photometric properties are in general best explained by extreme surface activity induced by rapid rotation. Although rapidly rotating cool giants (v sin i about 20 - 50 km/s) are often members of close binary systems in which tidal effects have produced synchronous rotation, there is no evidence for duplicity in FK Com. This has led Bopp and Stencel to suggest that the FK Com stars are coalesced binaries possibly evolved from W UMa systems. We propose to obtain IUE observations at minimum and maximum of a fully developed photometric wave, when the active regions are facing and directed away from the observer respectively. The light variations will be monitored it Villanova during 1983-1984 to determine the optimum time for scheduling the lUE observations. The previous IUE observations of FK Com were made when no photometry was available or when the light variations were small. We also propose to observe during a flare. The flaring activity will be monitored b), H-alpha photometry. During 1982 at least three long-lived (3-10d) flare events were seen.

  1. Photometry with Multi-anode Microchannel Arrays (mamas) and Charge Injection Devices (cids)

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.

    1984-01-01

    The characteristics of two kinds of detectors are summarized with emphasis on those aspects that would affect their use in high accuracy astronomical photometry. The first type, the multianode microchannel arrays (MAMA), are a family of pulse counting array detectors. Components and operation principles are reviewed and quantum efficiency, noise characteristics, and dynamic range characteristics are described. The second type, charge injection devices (CID), are discussed in reference to their applicability to photometric detection at optical wavelengths.

  2. Photometry Of The Semi-regular Variable Tx Tau

    Microsoft Academic Search

    Katherine Wyman; G. Spear; K. McLin; L. Cominsky; L. Mankiewicz; D. Reichart; K. Ivarsen

    2009-01-01

    We report V-band and I-band photometry for the SRA type variable TX Tau. Photometry was obtained using the robotic telescope GORT at the Hume Observatory (NASA funded through Sonoma State University) and the PROMPT robotic telescopes at Cerro Tololo Inter-American Observatory (NSF and NASA funded through the University of North Carolina). Photometry was also obtained using the PI of the

  3. BIASES ON INITIAL MASS FUNCTION DETERMINATIONS. III. CLUSTER MASSES DERIVED FROM UNRESOLVED PHOTOMETRY

    SciTech Connect

    Maiz Apellaniz, J., E-mail: jmaiz@iaa.es

    2009-07-10

    It is currently common to use spatially unresolved multifilter broadband photometry to determine the masses of individual stellar clusters (and hence the cluster mass function, CMF). I analyze the stochastic effects introduced by the sampling of the stellar initial mass function (SIMF) in the derivation of the individual masses and the CMF, and I establish that such effects are the largest contributor to the observational uncertainties. An analytical solution, valid in the limit where uncertainties are small, is provided to establish the range of cluster masses over which the CMF slope can be obtained with a given accuracy. The validity of the analytical solution is extended to higher mass uncertainties using Monte Carlo simulations and the Gamma approximation. The value of the Poisson mass is calculated for a large range of ages and a variety of filters for solar-metallicity clusters measured with single-filter photometry. A method that uses the code CHORIZOS is presented to simultaneously derive masses, ages, and extinctions. The classical method of using unweighted UBV photometry to simultaneously establish ages and extinctions of stellar clusters is found to be unreliable for clusters older than {approx}30 Ma, even for relatively large cluster masses. On the other hand, augmenting the filter set to include longer-wavelength filters and using weights for each filter increases the range of masses and ages that can be accurately measured with unresolved photometry. Nevertheless, a relatively large range of masses and ages is found to be dominated by SIMF sampling effects that render the observed masses useless, even when using UBVRIJHK photometry. A revision of some literature results affected by these effects is presented and possible solutions for future observations and analyses are suggested.

  4. Zinc, lead and cadmium accumulation and tolerance in Typha latifolia as affected by iron plaque on the root surface

    Microsoft Academic Search

    Zhihong Ye; Alan J. M Baker; Ming-Hung Wong; Arthur J Willis

    1998-01-01

    The effects of iron plaque on the growth of Typha latifolia L. and its accumulation of zinc (Zn), lead (Pb) and cadmium (Cd) were investigated under field conditions and in nutrient solution cultures in the laboratory. In the field, Zn concentrations (but not Cd) on the root surface were positively related to Fe concentrations on the root surface. In the

  5. Factors affecting the wettability of different surface materials with vegetable oil at high temperatures and its relation to cleanability

    NASA Astrophysics Data System (ADS)

    Ashokkumar, Saranya; Adler-Nissen, Jens; Møller, Per

    2012-12-01

    The main aim of the work was to investigate the wettability of different surface materials with vegetable oil (olive oil) over the temperature range of 25-200 °C to understand the differences in cleanability of different surfaces exposed to high temperatures in food processes. The different surface materials investigated include stainless steel (reference), PTFE (polytetrafluoroethylene), silicone, quasicrystalline (Al, Fe, Cr) and ceramic coatings: zirconium oxide (ZrO2), zirconium nitride (ZrN) and titanium aluminum nitride (TiAlN). The ceramic coatings were deposited on stainless steel with two different levels of roughness. The cosine of the contact angle of olive oil on different surface materials rises linearly with increasing temperature. Among the materials analyzed, polymers (PTFE, silicone) gave the lowest cos ? values. Studies of the effect of roughness and surface flaws on wettability revealed that the cos ? values increases with increasing roughness and surface flaws. Correlation analysis indicates that the measured contact angle values gave useful information for grouping easy-clean polymer materials from the other materials; for the latter group, there is no direct relation between contact angle and cleanability. In addition to surface wettability with oil many other factors such as roughness and surface defects play an essential role in determining their cleanability.

  6. Volatile Organic Compound (VOC) emissions from feedlot pen surface materials as affected by within pen location, moisture, and temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A laboratory study was conducted to evaluate the effects of pen location, moisture, and temperature on emissions of volatile organic compounds (VOC) from surface materials obtained from feedlot pens where beef cattle were fed a diet containing 30% wet distillers grain plus solubles. Surface material...

  7. Accurate photometry of extended spherically symmetric sources

    NASA Astrophysics Data System (ADS)

    Anders, P.; Gieles, M.; de Grijs, R.

    2006-05-01

    We present a new method to derive reliable photometry of extended spherically symmetric sources from HST images (WFPC2, ACS/WFC and NICMOS/NIC2 cameras), extending existing studies of point sources and marginally resolved sources. We develop a new approach to accurately determine intrinsic sizes of extended spherically symmetric sources, such as star clusters in galaxies beyond the Local Group (at distances ?20 Mpc), and provide a detailed cookbook to perform aperture photometry on such sources, by determining size-dependent aperture corrections (ACs) and taking sky oversubtraction as a function of source size into account. In an extensive Appendix, we provide the parameters of polynomial relations between the FWHM of various input profiles and those obtained by fitting a Gaussian profile (which we have used for reasons of computational robustness, although the exact model profile used is irrelevant), and between the intrinsic and measured FWHM of the cluster and the derived AC. Both relations are given for a number of physically relevant cluster light profiles, intrinsic and observational parameters. AC relations are provided for a wide range of apertures. Depending on the size of the source and the annuli used for the photometry, the absolute magnitude of such extended objects can be underestimated by up to 3 mag, corresponding to an error in mass of a factor of 15. We carefully compare our results to those from the more widely used DeltaMag method, and find an improvement of a factor of 3-40 in both the size determination and the AC.

  8. Quick and Dirty WFPC2 Stellar Photometry

    NASA Technical Reports Server (NTRS)

    Mighell, Kenneth J.

    2001-01-01

    The latest release of the IRAF (Image Reduction and Analysis Facility) MXTOOLS package includes the new tasks QDWFPC2 (Quick and Dirty Wide Field and Planetary Camera, which does quick CCD (charge-coupled device) stellar photometry on two Hubble Space Telescope (HST) WFPC2 (Wide Field and Planetary Camera) observations: WFPC2COLOR, which converts HST WFPC2 instrumental magnitudes to standard colors using the Holtzman et al. color equations, and QDCMD (Quick and Dirty Color Magnitude Diagram), which reads the output of WFPC2COLOR and displays a color-magnitude diagram on a user-chosen graphics device.

  9. New BVR Photometry of BL Camelopardalis

    NASA Astrophysics Data System (ADS)

    Joner, Michael D.

    2015-01-01

    New BVR photometry of the SX Phe star BL Camelopardalis has been secured with the 0.9 m reflector at the BYU West Mountain Observatory. The new data have been used to determine times of maximum light, standardize light curves in each of the three filters, and examine the frequencies that are currently detectable in the light curves from a single location.We acknowledge the Brigham Young University College of Physical and Mathematical Sciences as well as the Department of Physics and Astronomy for continued support of this and other research efforts currently being done at the West Mountain Observatory.

  10. Simultaneous Filter Photometry of V1727 Cygni

    NASA Astrophysics Data System (ADS)

    Sundin, Emma; Mason, P. A.; Robinson, E. L.; Morales, J.; Gomez, S.; Gonzalez, R.; Lopez, I.; Bell, K.

    2014-01-01

    We present high speed optical photometry of the low mass X-ray binary V1727 Cygni. Simultaneous observations were obtained during five consecutive nights in 2013 using McDonald Observatory's 2.7-m and 2.1-m telescopes using u' and R filters respectively. There is very little variation in the u' intensity. The R data displays night to night and orbital period variations. We discuss constraints on system properties provided by these multi-filter data. This program is funded by NSF grant 0958783.

  11. Charles Nordmann and Multicolour Stellar Photometry

    NASA Astrophysics Data System (ADS)

    Lequeux, James

    2010-11-01

    Charles Nordmann (1881-1940), an astronomer at the Paris Observatory, was the first to determine the effective temperature of stars with his photometre heterochrome, simultaneously and independently of Rosenberg, Wilsing and Scheiner in Germany. He is also the remote precursor of the multicolour photometry of Johnson and Morgan. In spite of the quality of his temperature determinations, which were as good or better than those made by spectrophotometry, he rapidly fell into oblivion because of some failures in his scientific work. We examine his activity in the international context of the time, and explain why he has been forgotten, to be rediscovered only recently.

  12. How surface fire in Siberian Scots pine forests affects soil organic carbon in the forest floor: Stocks, molecular structure, and conversion to black carbon (charcoal)

    Microsoft Academic Search

    Claudia I. Czimczik; Caroline M. Preston; Michael W. I. Schmidt; Ernst-Detlef Schulze

    2003-01-01

    In boreal forests, fire is a frequent disturbance and converts soil organic carbon (OC) to more degradation-resistant aromatic carbon, i.e., black carbon (BC) which might act as a long-term atmospheric-carbon sink. Little is known on the effects of fires on boreal soil OC stocks and molecular composition. We studied how a surface fire affected the composition of the forest floor

  13. Loss of solar wind plasma neutrality and affect on surface potentials near the lunar terminator and shadowed polar regions

    E-print Network

    California at Berkeley, University of

    a particle-in- cell code. It is found that thermal electrons will diffuse into the void ahead of the ions-solar angles approaching 90°, photoelectric currents charge the surface a few volts positive. On the nightside

  14. FACTORS AFFECTING THE LONG-TERM RESPONSE OF SURFACE WATERS TO ACIDIC DEPOSITION: STATE-OF-THE-SCIENCE

    EPA Science Inventory

    Recent intensive study of the causes of surface water acidification has led to numerous hypothesized controlling mechanisms. Among these are the salt-effect reduction of alkalinity, the base cation buffering and sulfate adsorption capacities of soils, availability of weatherable ...

  15. The effect of MTAD, an endodontic irrigant, on fibroblast attachment to periodontally affected root surfaces: A SEM analysis

    PubMed Central

    Ghandi, Mostafa; Houshmand, Behzad; Nekoofar, Mohammad H.; Tabor, Rachel K.; Yadeghari, Zahra; Dummer, Paul M. H.

    2013-01-01

    Background: Root surface debridement (RSD) is necessary to create an environment suitable for reattachment of the periodontium. Root surface conditioning may aid the formation of a biocompatible surface suitable for cell reattachment. BioPure™ MTAD (mixture of Doxycycline, citric acid and a detergent) is an endodontic irrigant with antibacterial properties and the ability to remove smear layer. It was hypothesized that MTAD may be useful for root surface conditioning. The efficacy of MTAD as a conditioner was measured by examining fibroblast attachment to root surfaces. Materials and Methods: Thirty-two specimens of human teeth with advanced periodontal disease were used. The surfaces were root planed until smooth. Half of the specimens were treated with 0.9% saline and the other samples with Biopure MTAD. As a negative control group, five further samples were left unscaled with surface calculus. Human gingival fibroblast cells HGF1-PI1 were cultured and poured over the tooth specimens and incubated. After fixation, the samples were sputter-coated with gold and examined with a SEM. The morphology and number of attached, fixed viable cells were examined. The data was analysed using the Mann-Whitney-U statistical test. Results: There was no significant difference between the numbers of attached cells in the experimental group treated with MTAD and the control group treated with saline. Little or no attached cells were seen in the negative control group. Conclusion: RSD created an environment suitable for cell growth and attachment in a laboratory setting. The use of MTAD did not promote the attachment and growth of cells on the surface of human roots following RSD. PMID:23869124

  16. Quasar Selection using Optical Photometry and Variability

    NASA Astrophysics Data System (ADS)

    Peters, Christina M.; Richards, Gordon T.; Myers, Adam D.; Ross, Nicholas

    2015-01-01

    We used the Non-parametric Bayesian Classification Kernel Density Estimation (NBC KDE) quasar selection algorithm to identify 30,755 type 1 quasar candidates on the Sloan Digital Sky Survey (SDSS) Stripe 82 using the combination of optical photometry and variability. Optical photometry is taken from the SDSS-I/II, while the variability parameters are calculated by fitting the structure function of the object with a power law. Selection was based on a training sample of 13,784 spectroscopically-confirmed type 1 quasars from the SDSS-I/II and the Baryon Oscillation Spectroscopic Survey (BOSS). Using variability alone, colors alone, and combining variability and colors we achieve 85%, 90%, and 95% quasar completeness respectively, with particular improvement in the selection of quasars at 2.7

  17. Speckle Interferometry and Photometry of Binary Stars

    NASA Astrophysics Data System (ADS)

    Genet, Russell M.; Hartkopf, William I.; Clark, R. Kent; Hardersen, Paul; Wren, Paul; Wallace, Daniel; Gelston, Ryan

    2013-08-01

    Binary orbits, when combined with parallaxes, yield dynamical masses, while photometry of the components restrains astrophysical models. Both are vital to understanding stellar evolution. Speckle interferometry, which is telescope resolution limited as opposed to seeing limited, allows observation of close, short-period binaries. We will use our next-generation, ultra-portable, low cost, EMCCD based speckle camera to observe some 500 binaries. We will confirm Hipparcos/Tycho double star discoveries as candidates for new binaries, classify new pairs by determining if their motion is curved (binary) or linear (optical double), add high-accuracy speckle observations that will allow the first determination of orbits, refine existing orbits by extending orbital coverage with speckle observations, and obtain precise photometry of binary components to link photometric with dynamical masses. For a decade, PI Genet has held undergraduate astronomy research seminars at Cuesta College that feature published student observations of binary stars. This run will demonstrate that student researchers can be an integral part of speckle interferometry runs at major observatories.

  18. Polarimetric Retrievals of Surface and Aerosol Properties in the Region Affected by the Deepwater Horizon Oil Spill

    Microsoft Academic Search

    M. Ottaviani; B. Cairns; J. Chowdhary; K. D. Knobelspiesse; R. A. Ferrare; C. A. Hostetler; J. W. Hair; R. Rogers; M. D. Obland; P. Zhai; Y. Hu

    2010-01-01

    In July 2010, the Research Scanning Polarimeter (RSP) effectuated two flights in two consecutive days over the region affected by the oil spill of the Deepwater Horizon offshore platform. Integrated on the NASA Langley B-200 aircraft, the instrument is deployed together with the High Spectral Resolution Lidar (HSRL), which provides information on the distribution of the aerosol layers beneath the

  19. Wide-field stellar photometry in Piwnice Observatory

    E-print Network

    Gracjan Maciejewski

    2007-12-17

    In this paper research projects based on the wide-field CCD photometry performed in Piwnice Observatory are discussed. The used telescopes, as well as dedicated software pipeline for data reduction are presented. The prospects for collaboration between Polish and Bulgarian institutes in the field of wide-field photometry are also discussed.

  20. DOPHOT, a CCD photometry program: Description and tests

    Microsoft Academic Search

    Paul L. Schechter; Mario Mateo; Abhijit Saha

    1993-01-01

    The design considerations and operational features of DOPHOT, a point-spread function (PSF) fitting photometry program, are described. Some relevant details of the PSF fitting are discussed. The quality of the photometry returned by DOPHOT is assessed via reductions of an 'artificial' globular cluster generated from a list of stars with known magnitudes and colors. Results from comparative tests between DOPHOT

  1. Photometry of Mercury from SOHO\\/LASCO and Earth

    Microsoft Academic Search

    Anthony Mallama; Dennis Wang; Russell A. Howard

    2002-01-01

    CCD observations of Mercury were obtained with the large angle spectrometric coronograph (LASCO) on the solar and heliospheric observatory spacecraft, near superior and inferior solar conjunctions. Whole disk photometry was extracted from the orange and blue filter images and transformed to V magnitudes on the UBV system. The LASCO data were combined with ground-based, V-filter photometry acquired at larger elongation

  2. JHK photometry of selected Trojan and Hilda asteroids

    NASA Technical Reports Server (NTRS)

    Smith, Dale W.; Johnson, Paul E.; Buckingham, William L.; Shorthill, Richard W.

    1992-01-01

    No entirely satisfactory match has been established between the present JHK photometry of selected Hilda and Trojan asteroids and photometry for both main belt asteroids and laboratory samples. It is noted that while the leading Trojans and Hildas exhibit similar and homogeneous JHK colors, the trailing Trojans appear to be more heterogeneous. Charcoal and magnetite provide the best match in terms of JHK colors.

  3. Visible and infrared photometry of Kuiper Belt objects: searching for evidence of trends

    E-print Network

    Sheppard, Scott S.

    Visible and infrared photometry of Kuiper Belt objects: searching for evidence of trends Neil Mc. © 2003 Elsevier Science (USA). All rights reserved. Keywords: Kuiper Belt objects; Photometry; Infrared

  4. Monoclonal antibodies reactive with secreted-excreted products from the amphids and the cuticle surface of Globodera pallida affect nematode movement and delay invasion of potato roots.

    PubMed

    Fioretti, L; Porter, A; Haydock, P J; Curtis, R

    2002-12-19

    This paper describes Excreted-secreted proteins (ES) proteins that were immunolocalised in the cuticle, amphids and subventral glands of second stage juveniles of the two species of potato cyst nematodes (Globodera pallida and Globodera rostochiensis). Monoclonal antibodies reactive with these ES proteins were used in a bioassay to investigate their effect on nematode movement and on their ability to invade potato roots. Antibodies recognising the nematode cuticle surface and the amphids affected nematode movement and delayed nematode penetration of roots. These effects were temporary, since the nematodes were able to recover and infect potato roots. Movement of second stage juveniles treated with the antibodies was impaired for the first 30 min after inoculation: the juveniles remained close to the point of introduction and moved slowly and abnormally. They recovered normal movement after 1-2 h, possibly because the turnover rate of the secreted proteins meant that they were no longer blocked by the monoclonal antibodies. No effect was observed on second stage juveniles treated with an antibody reactive with secretions from the oesophageal glands. Nematodes treated with antibodies reactive with the nematode cuticle surface were notably more affected than those treated with other antibodies; nematodes failed to recover movement when in continuous contact with the antibodies. It is possible that the physical presence of the antibodies on the nematode surface affected their motility. Nematodes treated with antibodies reactive with secretions from the amphids were temporarily unable to move towards potato roots and their exploratory behaviour was greatly affected by the antibody treatment. Whether these antibodies were able to inhibit temporarily the function of the amphids or this effect was due to physical presence of the antibodies blocking the amphidial pore remains to be determined. PMID:12464417

  5. Ten Recent Enhancements To Aperture Photometry Tool

    NASA Astrophysics Data System (ADS)

    Laher, Russ; Rebull, L. M.; Gorjian, V.

    2013-01-01

    Aperture Photometry Tool is free, multi-platform, easy-to-install software for astronomical research, as well as for learning, visualizing, and refining aperture-photometry analyses. This mature software has been under development for five years, and is a silent workhorse of the NASA/IPAC Teacher Archive Research Program. Software version 2.1.5 is described by Laher et al., Publications of the Astronomical Society of the Pacific, Vol. 124, No. 917, pp. 737-763, (July 2012). Four software upgrades have been released since the publication, which include new capabilities, increased speed, more user-friendliness, and some minor bug fixes. Visit www.aperturephotometry.org to download the latest version. The enhancements are as follows: 1) Added new Tools menu option to write selected primary-image data to a comma-separated-value file (for importing into Excel); 2) Added a new display of the color-table levels on a separate panel; 3) Added a new tool to measure the angular separation between positions on the thumbnail image, via mouse-cursor drag and release; 4) Added a new tool to overlay an aperture at user-specified coordinates (in addition to aperture overlay via mouse click); 5) Speeded up the source-list tool with optional multithreading in its automatic mode (allowed thread number is user-specifiable); 6) Added a new “Number” column to the output aperture-photometry-table file in order to track the input source order (multithreading reorders the output); 7) Upgraded the source-list tool to accept input source lists containing positions in sexagesimal equatorial coordinates (in addition to decimal degrees, or, alternatively, pixel coordinates); 8) Added a new decimal/sexagesimal converter; 9) Upgraded the source-list creation tool to compute the detection threshold using robust estimates of the local background and local data dispersion, where the user can select the grid and window sizes for these local calculations; and 10) Modified the batch mode to optionally generate a source list. These upgrades increase the software's utility, and more improvements are planned for future releases.

  6. Surface photometry of radio galaxies. II - Cluster sources

    NASA Technical Reports Server (NTRS)

    Owen, Frazer N.; White, Richard A.

    1991-01-01

    R-band CCD photometric observations are reported for 52 radio galaxies in clusters for which good radio maps are available. Data obtained with the No. 1 0.9-m telescope at KPNO (following the procedures described by Owen and Laing, 1989) are presented in tables and graphs and discussed in detail. Optical and radio luminosity are found to be well correlated in twin-jet, fat-double, narrow-angle-tail, and small-twin-jet sources, all of which are clearly distinguished from the classical doubles as in the scheme of Fanaroff and Riley (1974). It is also shown that the elliptical parent galaxies of the extended radio sources form a one-parameter family with the optical luminosity as the key parameter.

  7. Voyager photometry of Triton - Haze and surface photometric properties

    NASA Technical Reports Server (NTRS)

    Hillier, J.; Helfenstein, P.; Verbiscer, A.; Veverka, J.

    1991-01-01

    The Voyager whole-disk observations of Triton at 0.41, 0.48, and 0.56 micron filter wavelengths are analyzed using a model which combines an improved version of Hapke's photometric equation with a thin atmospheric haze layer in the appropriate spherical geometry. The model is shown to describe accurately the phase curves over a range of phase angles and to agree with disk-resolved brightness scans along the photometric equator and mirror meridian. According to the model, the photometric parameters of Triton's regolith are reasonably typical of icy satellites, except for the extremely high (close to unity) single-scattering albedo.

  8. The surface photometry catalogue of the ESO-Uppsala galaxies

    Microsoft Academic Search

    Andris Lauberts; Edwin A. Valentijn

    1989-01-01

    Not Available Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Keywords (in text query field) Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints

  9. New Insights into Stellar Astrophysics from High-Precision Photometry

    NASA Astrophysics Data System (ADS)

    Soderblom, David R.

    2013-01-01

    The rich harvest of information on the occurrence and nature of planets around solar-type stars is why Kepler was built, but equally profound from this mission are the insights and quantitative physical studies of stars. The Kepler sample is dominated by the ~100,000 stars that are like the Sun, yet the Kepler field includes examples of nearly every stellar type. Kepler's exquisite photometry - continuously over an extended time - has enabled the detection of new phenomena and has provided critical tests of stellar models. In this brief review I will summarize some of the exciting new findings that Kepler has made possible, including: Stellar surface granulation in late-type stars; Evidence for rapid rotation of the cores of some evolved stars; Flares on G, K and M stars; Precise ages for older solar-type stars; Evidence for "mixed" modes in evolved stars that couple p-modes to interior g-modes; Stellar differential rotation; Detection of stellar activity cycles from asteroseismology; Mixing processes in stars; Detailed studies of eclipsing binaries; A comparison of the Sun to similar stars; Pulsating stars; Stellar surface features revealed by planet transits.

  10. Kinemetry: a generalisation of photometry to the higher moments of the line-of-sight velocity distribution

    E-print Network

    Davor Krajnovic; Michele Cappellari; P. Tim de Zeeuw; Yannick Copin

    2005-12-07

    We present a generalisation of surface photometry to the higher-order moments of the line-of-sight velocity distribution of galaxies observed with integral-field spectrographs. The generalisation follows the approach of surface photometry by determining the best fitting ellipses along which the profiles of the moments can be extracted and analysed by means of harmonic expansion. The assumption for the odd moments (e.g. mean velocity) is that the profile along an ellipse satisfies a simple cosine law. The assumption for the even moments (e.g velocity dispersion) is that the profile is constant, as it is used in surface photometry. We find that velocity profiles extracted along ellipses of early-type galaxies are well represented by the simple cosine law (with 2% accuracy), while possible deviations are carried in the fifth harmonic term which is sensitive to the existence of multiple kinematic components, and has some analogy to the shape parameter of photometry. We compare the properties of the kinematic and photometric ellipses and find that they are often very similar. Finally, we offer a characterisation of the main velocity structures based only on the kinemetric parameters which can be used to quantify the features in velocity maps (abridged).

  11. TERMS PHOTOMETRY OF KNOWN TRANSITING EXOPLANETS

    SciTech Connect

    Dragomir, Diana; Kane, Stephen R.; Ciardi, David R.; Gelino, Dawn M.; Payne, Alan; Ramirez, Solange V.; Von Braun, Kaspar; Wyatt, Pamela [NASA Exoplanet Science Institute, Caltech, MS 100-22, Pasadena, CA 91125 (United States); Pilyavsky, Genady; Mahadevan, Suvrath; Wright, Jason T. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Zachary Gazak, J. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Rabus, Markus, E-mail: diana@phas.ubc.ca [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile)

    2011-10-15

    The Transit Ephemeris Refinement and Monitoring Survey conducts radial velocity and photometric monitoring of known exoplanets in order to refine planetary orbits and predictions of possible transit times. This effort is primarily directed toward planets not known to transit, but a small sample of our targets consists of known transiting systems. Here we present precision photometry for six WASP (Wide Angle Search for Planets) planets acquired during their transit windows. We perform a Markov Chain Monte Carlo analysis for each planet and combine these data with previous measurements to redetermine the period and ephemerides for these planets. These observations provide recent mid-transit times which are useful for scheduling future observations. Our results improve the ephemerides of WASP-4b, WASP-5b, and WASP-6b and reduce the uncertainties on the mid-transit time for WASP-29b. We also confirm the orbital, stellar, and planetary parameters of all six systems.

  12. Techniques for Automated Single-Star Photometry

    NASA Technical Reports Server (NTRS)

    Henry, Gregory W.

    2001-01-01

    Tennessee State University operates several automatic photoelectric telescopes (APTs) located at Fairborn Observatory in the Patagonia Mountains of southern Arizona. The APTs are dedicated to photometric monitoring programs that would be expensive and difficult to accomplish without the advantages of automation. I review the operation of two of the telescopes (a 0.75- and 0.80-meter (m) APT) and the quality-control techniques that result in the routine acquisition of single-star differential photometry with a precision of 0.001 mag for single observations and 0.0001 - 0.0002 mag for seasonal means. I also illustrate the capabilities of the APTS with sample results from a program to measure luminosity cycles in sun-like stars and a related program to search for the signatures of extrasolar planets around these stars.

  13. Photometry Analysis using Oukaimeden IRIS Data

    NASA Astrophysics Data System (ADS)

    Benkhaldoun, Z.; Siher, E.

    Since 1988, a Moroccan astronomers began a site evaluation of the Oukaimeden (2600m) in the mountain ATLAS chain. The site has been selected, in parallel, for installation of IRIS helioseismograph as one of the seven stations by the world. The Oukaimeden appeared to be a good site, when compared to other former observatories, in term of daytime sky transparency, photometry and extinction and ground climatology. We present here a results of one year (1997) clouds cover, extinction coefficient and transparency fluctuation's measurement, using a total solar intensity provided by IRIS helioseismograph. We also compared the results with the same works mad by Hill et al (1994) in the GONG site testing campaign and Benkhaldoun et al (1993) using a simple flux integration photometer.

  14. JHK photometry of WD 0950+139

    NASA Astrophysics Data System (ADS)

    Fulbright, Michael S.; Liebert, James

    1993-06-01

    We present results from several nights of JHK photometry of the hot DA white dwarf 0950+139. It has a significant infrared excess over the expected flux from the white dwarf alone, confirming a previous finding by Zuckerman et al. (1991). The infrared excess corresponds to an upper limit on the spectral type of a companion of M4 V. We consider two models for the infrared excess of 0950+139, involving either a mid-M dwarf or a substellar object as a close companion. If 0950+139 is a close binary with a period of days, we predict that we should detect variation in the infrared fluxes due to reprocessing by the companion. Such variation was not detected, which may mean the system has a different orbital period or an inclination near 0 deg.

  15. JHK photometry of WD 0950+139

    NASA Technical Reports Server (NTRS)

    Fulbright, Michael S.; Liebert, James

    1993-01-01

    We present results from several nights of JHK photometry of the hot DA white dwarf 0950+139. It has a significant infrared excess over the expected flux from the white dwarf alone, confirming a previous finding by Zuckerman et al. (1991). The infrared excess corresponds to an upper limit on the spectral type of a companion of M4 V. We consider two models for the infrared excess of 0950+139, involving either a mid-M dwarf or a substellar object as a close companion. If 0950+139 is a close binary with a period of days, we predict that we should detect variation in the infrared fluxes due to reprocessing by the companion. Such variation was not detected, which may mean the system has a different orbital period or an inclination near 0 deg.

  16. Photometry of small asteroids and cometary cores

    NASA Technical Reports Server (NTRS)

    Gehrels, T.; Wisniewski, W. Z.; Zellner, B. H.

    1986-01-01

    The first asteroid lightcurves have now been made with a new technique of CCD photometry. The apparent magnitude is fainter (V>17) than what can be done with the 1.52-m Catalina reflector with a photomultiplier photometer. With the CCD system, however, the lightcurve shows remarkably good repetition; finding the asteroid is, of course, no problem as the object is recognized later by its motion on the CCD. Asteroid 1985RV has a lightcurve amplitude of about 0.4 mag and its period of rotation P = 4.0 hours, on the assumption that the lightcurve has two maxima and two minima as is the case for nearly all other asteroids. The diameter is about 3 km. 1985RV is a first example of results that are being obtained on asteroids and comets with CCD in the Catalinas, Kitt Peak, and Cerro Tololo.

  17. Gaia photometry: methods, performances and problems

    NASA Astrophysics Data System (ADS)

    Jordi, C.

    2011-02-01

    We present the pipeline processing (for photometry and spectrophotometry) primarily based on the comparison of the observation with a prediction from the spectral energy distribution and total flux of the source and a set of parameters modelling the instrument properties observation-to-observation. Experiments on G white light calibration yield residuals well below one mmag for most of the cases, but for extreme colour stars. For blue and red spectra, tests up to now yield residuals significantly smaller than the observational noise, except for sources with very strong spectral features, which present flux residuals of 2-3% in the spectral lines (at G = 15). Work continues to account for all instrumental effects, to add complexity to the instrument model and to improve the processing pipeline.

  18. Detoxification of Implant Surfaces Affected by Peri-Implant Disease: An Overview of Non-surgical Methods

    PubMed Central

    Valderrama, Pilar; Blansett, Jonathan A; Gonzalez, Mayra G; Cantu, Myrna G; Wilson, Thomas G

    2014-01-01

    Objective: The aim of this review is to summarize the findings of studies that have evaluated non-surgical approaches for detoxification of implant body surfaces in vitro and in vivo, and to evaluate clinical trials on the use of these methodologies for treating peri-implant disease. Materials and methods: A literature search was conducted using MEDLINE (Pubmed) from 1966 to 2013. In vitro and in vivo studies as well as clinical trials on non-surgical therapy were evaluated. The outcome variables were the ability of the therapeutic method to eliminate the biofilm and endotoxins from the implant surface, the changes in clinical parameters including probing depth, clinical attachment levels, bleeding on probing; radiographic bone fill and histological re-osseointegration. Results: From 134 articles found 35 were analyzed. The findings, advantages and disadvantages of using lasers as well as mechanical and chemical methods are discussed. Most of the in vivo and human studies used combination therapies which makes determining the efficacy of one specific method difficult. Most human studies are case series with short term longitudinal analysis without survival or failure reports. Conclusion: Complete elimination of the biofilms is difficult to achieve using these approaches. All therapies induce changes of the chemical and physical properties of the implant surface. Re-osseointegration may be difficult to achieve if not impossible without surgical access to ensure thorough debridement of the defect and detoxification of the implant surface. Combination protocols for non-surgical treatment of peri-implantitis in humans have shown some positive clinical results but long-term evaluation to evaluate the validity and reliability of the techniques is needed. PMID:24894571

  19. Cationic screening of charged surface groups (carboxylates) affects electron transfer steps in photosystem-II water oxidation and quinone reduction.

    PubMed

    Karge, Oliver; Bondar, Ana-Nicoleta; Dau, Holger

    2014-10-01

    The functional or regulatory role of long-distance interactions between protein surface and interior represents an insufficiently understood aspect of protein function. Cationic screening of surface charges determines the morphology of thylakoid membrane stacks. We show that it also influences directly the light-driven reactions in the interior of photosystem II (PSII). After laser-flash excitation of PSII membrane particles from spinach, time courses of the delayed recombination fluorescence (10?s-10ms) and the variable chlorophyll-fluorescence yield (100?s-1s) were recorded in the presence of chloride salts. At low salt-concentrations, a stimulating effect was observed for the S-state transition efficiency, the time constant of O2-formation at the Mn4Ca-complex of PSII, and the halftime of re-oxidation of the primary quinone acceptor (Qa) by the secondary quinone acceptor (Qb). The cation valence determined the half-effect concentrations of the stimulating salt effect, which were around 6?M, 200?M and 10mM for trivalent (LaCl3), bivalent (MgCl2, CaCl2), and monovalent cations (NaCl, KCl), respectively. A depressing high-salt effect also depended strongly on the cation valence (onset concentrations around 2mM, 50mM, and 500mM). These salt effects are proposed to originate from electrostatic screening of negatively charged carboxylate sidechains, which are found in the form of carboxylate clusters at the solvent-exposed protein surface. We conclude that the influence of electrostatic screening by solvent cations manifests a functionally relevant long-distance interaction between protein surface and electron-transfer reactions in the protein interior. A relation to regulation and adaptation in response to environmental changes is conceivable. PMID:25062950

  20. Estimating environmental conditions affecting protozoal pathogen removal in surface water wetland systems using a multi-scale, model-based approach.

    PubMed

    Daniels, Miles E; Hogan, Jennifer; Smith, Woutrina A; Oates, Stori C; Miller, Melissa A; Hardin, Dane; Shapiro, Karen; Los Huertos, Marc; Conrad, Patricia A; Dominik, Clare; Watson, Fred G R

    2014-09-15

    Cryptosporidium parvum, Giardia lamblia, and Toxoplasma gondii are waterborne protozoal pathogens distributed worldwide and empirical evidence suggests that wetlands reduce the concentrations of these pathogens under certain environmental conditions. The goal of this study was to evaluate how protozoal removal in surface water is affected by the water temperature, turbidity, salinity, and vegetation cover of wetlands in the Monterey Bay region of California. To examine how protozoal removal was affected by these environmental factors, we conducted observational experiments at three primary spatial scales: settling columns, recirculating wetland mesocosm tanks, and an experimental research wetland (Molera Wetland). Simultaneously, we developed a protozoal transport model for surface water to simulate the settling columns, the mesocosm tanks, and the Molera Wetland. With a high degree of uncertainty expected in the model predictions and field observations, we developed the model within a Bayesian statistical framework. We found protozoal removal increased when water flowed through vegetation, and with higher levels of turbidity, salinity, and temperature. Protozoal removal in surface water was maximized (~0.1 hour(-1)) when flowing through emergent vegetation at 2% cover, and with a vegetation contact time of ~30 minutes compared to the effects of temperature, salinity, and turbidity. Our studies revealed that an increase in vegetated wetland area, with water moving through vegetation, would likely improve regional water quality through the reduction of fecal protozoal pathogen loads. PMID:25016109

  1. Hydrologic characterization of a permafrost-affected headwaters catchment using a coupled groundwater-surface water model and field measurements of active layer characteristics

    NASA Astrophysics Data System (ADS)

    Kikuchi, C.; Koch, J.; Steelman, C. M.; Schuster, P. F.

    2012-12-01

    Permafrost degradation is expected to change the quantity and quality of solute fluxes from northern watersheds. In particular, fluxes of organic carbon (OC) and mercury (Hg) are of great concern for aquatic and marine ecosystems in this area. The total export of OC and Hg depends upon hydrology of permafrost-affected catchments; in particular, the magnitude and extent of groundwater-surface water flows. Hydrologic processes in these catchments are complex and poorly understood; furthermore, understanding of groundwater-surface water interaction is greatly complicated by permafrost degradation. Hydrologic modeling and field studies at West Twin Creek - a permafrost-affected, experimental headwaters catchment in interior Alaska - have been undertaken to identify the dominant controls upon catchment hydrology, groundwater-surface water interaction, and export of OC and Hg. A coupled groundwater-surface water model was developed using the code GSFLOW, calibrated to several years of streamflow data. Sensitivity analysis revealed that groundwater-surface water flows are predominantly controlled by physical characteristics of the soil active layer in the catchment. A suite of measurements was designed to better constrain the properties of the soil active layer at West Twin Creek during a period of maximum thaw depth. Gridded permafrost probing and soil coring were undertaken along several transects through hillslope and riparian areas. Ground-penetrating radar (GPR) surveys were conducted to complement these point measurements, providing spatially continuous information on active layer thickness along survey lines. Soil coring and GPR surveys revealed distinct soil profiles and frost table depths at several hillslope locations. Soils varied from fine eolian silts to coarse schist cobbles, and differences corresponded to moisture, surface vegetation, and thaw depth. These differences may have large effects on moisture storage, hillslope hydraulic conductivity, and subsequently runoff potential. Artificial rainfall experiments were then performed to quantify surface runoff and interflow through organic and mineral horizons at control plots representative of each soil profile type. These experiments showed that water flow occurs predominantly at the interface between organic and mineral horizons in hillslope soils. The targeted measurements undertaken during this field campaign were used to revise the hydrologic model for the catchment, providing more accurate estimates of groundwater-surface water fluxes for the purposes of forecasting OC and Hg exports.

  2. Surfaces

    E-print Network

    DeMaio, Ernest Vincent, 1964-

    1989-01-01

    Surfaces is a collection of four individual essays which focus on the characteristics and tactile qualities of surfaces within a variety of perceived landscapes. Each essay concentrates on a unique surface theme and purpose; ...

  3. Energy absorption during impact on the proximal femur is affected by body mass index and flooring surface.

    PubMed

    Bhan, Shivam; Levine, Iris C; Laing, Andrew C

    2014-07-18

    Impact mechanics theory suggests that peak loads should decrease with increase in system energy absorption. In light of the reduced hip fracture risk for persons with high body mass index (BMI) and for falls on soft surfaces, the purpose of this study was to characterize the effects of participant BMI, gender, and flooring surface on system energy absorption during lateral falls on the hip with human volunteers. Twenty university-aged participants completed the study with five men and five women in both low BMI (<22.5 kg/m(2)) and high BMI (>27.5 kg/m(2)) groups. Participants underwent lateral pelvis release experiments from a height of 5 cm onto two common floors and four safety floors mounted on a force plate. A motion-capture system measured pelvic deflection. The energy absorbed during the initial compressive phase of impact was calculated as the area under the force-deflection curve. System energy absorption was (on average) 3-fold greater for high compared to low BMI participants, but no effects of gender were observed. Even after normalizing for body mass, high BMI participants absorbed 1.8-fold more energy per unit mass. Additionally, three of four safety floors demonstrated significantly increased energy absorption compared to a baseline resilient-rolled-sheeting system (% increases ranging from 20.7 to 28.3). Peak system deflection was larger for high BMI persons and for impacts on several safety floors. This study indicates that energy absorption may be a common mechanism underlying the reduced risk of hip fracture for persons with high BMI and for those who fall on soft surfaces. PMID:24837217

  4. How do Atmospheres Affect Planetary Temperatures? Activity B How do Atmospheres Produce their Effect Upon Surface Temperatures?

    NSDL National Science Digital Library

    In this kinesthetic activity, the concept of energy budget is strengthened as students conduct three simulations using play money as units of energy, and students serve as parts of a planetary radiation balance model. Students will determine the energy budget of a planet by manipulating gas concentrations, energy inputs and outputs in the system in this lesson that supports the study of climate on Mars, Mercury, Venus and Earth. The lesson supports understanding of the real-world problem of contemporary climate change. The resource includes a teacher's guide and several student worksheets. This is the second of four activities in the lesson, How do Atmospheres affect planetary temperatures?, within Earth Climate Course: What Determines a Planet's Climate? The resource aims to help students to develop an understanding of our environment as a system of human and natural processes that result in changes that occur over various space and time scales.

  5. Distribution and accumulation of heavy metals in surface sediments from a subtropical bay affected by the Special Economic Zone, China.

    PubMed

    Qiao, Yongmin; Pan, Hong; Yang, Yang; Gu, Jiguang; Zhao, Jiangang

    2013-01-01

    The concentrations of nine metals (Cd, Cr, Cu, Ni, Mn, Pb, Zn, Fe, and Al) in surface sediments from 14 sampling sites in Shantou Bay were determined in order to understand current metal levels and spatial distribution due to the rapid development of the Shantou Special Economic Zone. Results showed that metal concentrations in surface sediments varied from 0.31 to 1.74 mg kg(-1) for Cd, 35.98 to 74.19 mg kg(-1) for Cr, 24.43 to 79.24 mg kg(-1) for Cu, 428.45 to 809.87 mg kg(-1) for Mn, 16.91 to 31.51 mg kg(-1) for Ni, 35.59 to 64.84 mg kg(-1) for Pb, 84.91 to 246.51 mg kg(-1) for Zn, 2.93 to 3.93% for Fe, and 5.25 to 9.28% for Al. Although all metal concentrations in sediments meet Chinese National Standard Criteria for Marine Sediment Quality, both enrichment factor (EF) and geo-accumulation index (Igeo) show Pb and Cd pollution existed in the upper and middle bay, and pollution of other metals is also recorded in some sites depending on the sources; river input, sewage discharge, and port activities are the main sources of pollutant to the bay. PMID:23656944

  6. Application of an Environmental Decision Support System to a Water Quality Trading Program Affected by Surface Water Diversions

    NASA Astrophysics Data System (ADS)

    Obropta, Christopher C.; Niazi, Mehran; Kardos, Josef S.

    2008-12-01

    Environmental decision support systems (EDSSs) are an emerging tool used to integrate the evaluation of highly complex and interrelated physicochemical, biological, hydrological, social, and economic aspects of environmental problems. An EDSS approach is developed to address hot-spot concerns for a water quality trading program intended to implement the total maximum daily load (TMDL) for phosphorus in the Non-Tidal Passaic River Basin of New Jersey. Twenty-two wastewater treatment plants (WWTPs) spread throughout the watershed are considered the major sources of phosphorus loading to the river system. Periodic surface water diversions to a major reservoir from the confluence of two key tributaries alter the natural hydrology of the watershed and must be considered in the development of a trading framework that ensures protection of water quality. An EDSS is applied that enables the selection of a water quality trading framework that protects the watershed from phosphorus-induced hot spots. The EDSS employs Simon’s (1960) three stages of the decision-making process: intelligence, design, and choice. The identification of two potential hot spots and three diversion scenarios enables the delineation of three management areas for buying and selling of phosphorus credits among WWTPs. The result shows that the most conservative option entails consideration of two possible diversion scenarios, and trading between management areas is restricted accordingly. The method described here is believed to be the first application of an EDSS to a water quality trading program that explicitly accounts for surface water diversions.

  7. Apatite formation on bioactive calcium-silicate cements for dentistry affects surface topography and human marrow stromal cells proliferation.

    PubMed

    Gandolfi, Maria Giovanna; Ciapetti, Gabriela; Taddei, Paola; Perut, Francesca; Tinti, Anna; Cardoso, Marcio Vivan; Van Meerbeek, Bart; Prati, Carlo

    2010-10-01

    The effect of ageing in phosphate-containing solution of bioactive calcium-silicate cements on the chemistry, morphology and topography of the surface, as well as on in vitro human marrow stromal cells viability and proliferation was investigated. A calcium-silicate cement (wTC) mainly based on dicalcium-silicate and tricalcium-silicate was prepared. Alpha-TCP was added to wTC to obtain wTC-TCP. Bismuth oxide was inserted in wTC to prepare a radiopaque cement (wTC-Bi). A commercial calcium-silicate cement (ProRoot MTA) was tested as control. Cement disks were aged in DPBS for 5 h ('fresh samples'), 14 and 28 days, and analyzed by ESEM/EDX, SEM/EDX, ATR-FTIR, micro-Raman techniques and scanning white-light interferometry. Proliferation, LDH release, ALP activity and collagen production of human marrow stromal cells (MSC) seeded for 1-28 days on the cements were evaluated. Fresh samples exposed a surface mainly composed of calcium-silicate hydrates CSH (from the hydration of belite and alite), calcium hydroxide, calcium carbonate, and ettringite. Apatite nano-spherulites rapidly precipitated on cement surfaces within 5 h. On wTC-TCP the Ca-P deposits appeared thicker than on the other cements. Aged cements showed an irregular porous calcium-phosphate (Ca-P) coating, formed by aggregated apatite spherulites with interspersed calcite crystals. All the experimental cements exerted no acute toxicity in the cell assay system and allowed cell growth. Using biochemical results, the scores were: fresh cements>aged cements for cell proliferation and ALP activity (except for wTC-Bi), whereas fresh cements

  8. Spitzer/IRAC Photometry Of The Four Largest Uranian Satellites

    NASA Astrophysics Data System (ADS)

    Cartwright, Richard; Emery, J.; Rivkin, A.; Trilling, D.

    2012-10-01

    The surfaces of the four largest Uranian satellites are dominated by water ice and a spectrally neutral constituent that is likely carbonaceous in composition. CO2 ice has been detected on Ariel, Umbriel, and Titania, with no detection on the furthest regular Uranian satellite, Oberon (Grundy et al., 2003, 2006). Whether CO2 ice is primordial or is actively produced in the Uranian system is unclear; however, it seems unlikely that primordial CO2 ice would remain exposed on an icy satellite surface over the age of the Solar System. One possible mechanism for producing CO2 ice is bombardment of water ice and carbonaceous material by charged particles caught in Uranus’ magnetic field. Unlike the other large Uranian satellites, Oberon spends part of its orbit outside the confines of Uranus’ magnetic field, which might help explain why CO2 ice has yet to be detected on Oberon. We are using photometric data gathered by the Infrared Array Camera (IRAC), onboard the Spitzer Space Telescope (SST), in order to search for the signature of CO2 ice on Oberon, and confirm its presence on Ariel, Umbriel, and Titania at longer wavelengths than previous studies. IRAC collects data in four different channels, which are centered roughly at 3.6, 4.5, 5.8, and 8.0 µm. Additionally, we are gathering spectroscopic data using SpeX on IRTF, at similar longitudes to the IRAC observations, in order to characterize the distribution of CO2 ice on these icy satellites over a wide range of near-infrared wavelengths. Our preliminary photometry results for Oberon indicate that there is a steep reduction in reflected solar flux from channel 1 to channel 2, suggesting that surface materials are absorbing photons at wavelengths within the bandpass of channel 2. We will present the results of our photometric analysis of the four largest Uranian moons.

  9. Multicolour photometry of edge-on and box/peanut galaxies

    NASA Astrophysics Data System (ADS)

    Petrov, Georgi; Dettmar, Ralf-Jurgen

    We report the main results of the joint Bulgarian-German project for photometry of edge-on galaxies suspected to have box/peanut structures. CCD images for 30 such galaxies were taken with the 2_m (24 galaxies) and 60_cm (17 galaxies) telescopes as follows: (U), B, V, R, I CCD frames from the 2_m RCC telescope at the Rozhen Observatory with typical resolution 12"/mm = 0.62"/pix with binning and rarely 0.31"/pix, CCD camera "Photometrics" and (B), V, R, I frames on the 60_cm telescope at the Belogradchik Observatory with typical resolution of 27.5"/mm = 0.78"/pix with 3x binning, CCD camera ST--8. Standard stars in selected clusters (M 92, NGC 7790 or M 67), bias, dark and flat field frames were taken every night to calibrate the observations. Typical exposure times were from 2 to 5 min, so the bulge/disk regions were clear presented. All of the objects, observed in the optics, were reduced and classified in an uniform manner. Five galaxies from the list have been reclassified as box/peanut ones. Surface photometry of NGC 5610 and isophote maps of 16 other box/peanut galaxies are presented here. The observations and photometry data are a part of the Bulgarian Virtual Observatory.

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

    NASA Astrophysics Data System (ADS)

    Weiss, W. W.; Rucinski, S. M.; 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.

    2014-06-01

    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°), so up to about 15 bright stars can be observed simultaneously, sampled in 32 × 32 pixels 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 evolutionary stages, and evolved medium-mass stars at the very end of their nuclear burning phases. The goals of BRITE-Constellation are to (1) measure p- and g-mode pulsations to probe the interiors and ages of stars through asteroseismology; (2) look for varying spots on the stars surfaces carried across the stellar disks by rotation, which are the sources of co-rotating interaction regions in the winds of the most luminous stars, probably arising from magnetic subsurface convection; and (3) search for planetary transits.

  11. Accuracy of stellar parameters determined from multicolor photometry

    NASA Astrophysics Data System (ADS)

    Sichevskij, S. G.; Mironov, A. V.; Malkov, O. Yu.

    2014-04-01

    The development and application of new methods for intelligent analysis and extraction of information from digital sky surveys carried out in various spectral domains have now become a popular field in astrophysical research and, in particular, in stellar studies. Modern large-scale photometric surveys provide data for 105-106 relatively faint objects, and the lack of spectroscopic data can be compensated by the cross identification of the objects followed by an analysis of all catalogued photometric data. In this paper we investigate the possibility of determining the effective temperature, surface gravity, total extinction, and the total-to-selective extinction ratio based on the photometry provided in the 2MASS, SDSS, and GALEX surveys, and estimate the accuracy of the inferred parameters. We use a library of theoretical spectra to compute the magnitudes of stars in the photometric bands of the above surveys for various sets of input parameters. We compare the differences between the computed magnitudes with the errors of the corresponding surveys. We find that stellar parameters can be computed over a sizable domain of the parameter space. We estimate the accuracy of the resulting parameters. We show that the presence of far-ultraviolet data in the available set of observed magnitudes increases the accuracy of the inferred parameters.

  12. The expected Gaia revolution in asteroid science: Photometry and spectroscopy

    NASA Astrophysics Data System (ADS)

    Cellino, A.

    2014-07-01

    Gaia is expected to produce a major revolution in our knowledge of the asteroids. Apart from a huge improvement in the accuracy of the orbital elements of these objects, something which is a ''natural'' consequence of the unprecedented astrometric accuracy of Gaia, we can also expect that the photometric and spectrophotometric performances of the Gaia detectors will be such to substantially move ahead the frontier of the domain of physical characterization of asteroids by means of remote observations. A list of physical properties, that will be derived from the analysis of the detections corresponding to different observed transits of each object in the Gaia focal plane during five years of operational activity, includes masses, sizes, average densities, spin properties, reflectance spectra, albedos, as well as a new taxonomic classification. In this review, the focus will be on Gaia photometry and spectrophotometry. The method of photometric inversion of sparse photometric data developed to reduce Gaia photometric data of asteroids will be described, and its expected performances will be discussed. In particular, the choice of assuming for the objects the shapes of ideal triaxial ellipsoids, fairly simplistic in an era in which much more refined shape models are currently used in photometric inversion methods, will be justified by the need of minimizing the CPU time needed to process data for hundreds of thousands of objects in a reasonable time. The processing of spectrophotometric data will be also described. These data will produce a huge data set of reflectance spectra of asteroids. A particular advantage of these data will be that of including also the blue part of the spectrum, which has been substantially lost since the epoch in which the CCD detectors have replaced the older photomultipliers used for UBVRI photometry. The big data set of new asteroid spectra will be also used to develop a new asteroid taxonomy, used new algorithms developed for this purpose. Coupled with the determination of reasonably accurate masses and bulk densities for the biggest 100 asteroids, Gaia data will open a new era in asteroid science, and will allow us to answer some fundamental questions, including the relation between internal structure and surface properties. The resulting post-Gaia scenario in asteroid science will be very much improved with respect to the current state of the art.

  13. Detection of Extrasolar Planets by Transit Photometry

    NASA Technical Reports Server (NTRS)

    Borucki, William; Koch, David; Webster, Larry; Dunham, Edward; Witteborn, Fred; Jenkins, Jon; Caldwell, Douglas; Showen, Robert; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    A knowledge of other planetary systems that includes information on the number, size, mass, and spacing of the planets around a variety of star types is needed to deepen our understanding of planetary system formation and processes that give rise to their final configurations. Recent discoveries show that many planetary systems are quite different from the solar system in that they often possess giant planets in short period orbits. The inferred evolution of these planets and their orbital characteristics imply the absence of Earth-like planets near the habitable zone. Information on the properties of the giant-inner planets is now being obtained by both the Doppler velocity and the transit photometry techniques. The combination of the two techniques provides the mass, size, and density of the planets. For the planet orbiting star HD209458, transit photometry provided the first independent confirmation and measurement of the diameter of an extrasolar planet. The observations indicate a planet 1.27 the diameter of Jupiter with 0.63 of its mass (Charbonneau et al. 1999). The results are in excellent agreement with the theory of planetary atmospheres for a planet of the indicated mass and distance from a solar-like star. The observation of the November 23, 1999 transit of that planet made by the Ames Vulcan photometer at Lick Observatory is presented. In the future, the combination of the two techniques will greatly increase the number of discoveries and the richness of the science yield. Small rocky planets at orbital distances from 0.9 to 1.2 AU are more likely to harbor life than the gas giant planets that are now being discovered. However, new technology is needed to find smaller, Earth-like planets, which are about three hundred times less massive than Jupiter-like planets. The Kepler project is a space craft mission designed to discover hundreds of Earth-size planets in and near the habitable zone around a wide variety of stars. To demonstrate that the technology exists to find such small planets, our group has conducted an end-to-end system test. The results of the laboratory tests are presented and show that we are ready to start the search for Earth-size planets.

  14. Cell surface protein C23 affects EGF-EGFR induced activation of ERK and PI3K-AKT pathways.

    PubMed

    Lv, Shunzeng; Dai, Congxin; Liu, Yuting; Sun, Bowen; Shi, Ranran; Han, Mingzhi; Bian, Ruixiang; Wang, Renzhi

    2015-02-01

    The epidermal growth factor (EGF) pathway has been reported as canonical causes in cancer development. Meanwhile, the involvement of C23 in multiple signaling pathways has been also investigated (Lv et al., 2014). However, the effect of C23 on EGF pathway in glioblastoma is not fully characterized. In the present study, C23 and the epidermal growth factor receptor (EGFR) of U251 cell line were inhibited by C23 and EGFR antibodies, respectively; and then C23 and EGFR siRNAs were used to knock down endogenous C23 and EGFR, respectively. In addition, soft-agar and MTT assay were also introduced. Compared with control, either C23 or EGFR antibodies efficiently repressed the phosphorylation levels of ERK1/2 (p<0.000) and AKT (p<0.000). Similarly, either C23 or EGFR siRNAs indeed resulted in C23 and EGFR knockdown, and further suppressed the expression of p-ERK1/2 and p-AKT. Most importantly, immunoprecipitation revealed C23 interacted with EGFR once U251 was exposed to EGF treatment. In addition, the MTT and soft-agar assay also identified that C23 or EGFR siRNAs could obviously affected cell growth (p=0.004) and invasiveness, as cell viability and colony formation decreased markedly. Our results suggest that C23 plays a crucial role in activation of EGF-induced ERK and PI3K-AKT pathways via interacting with EGFR; furthermore, C23 could be indicative of an important factor in glioblastoma development and a useful target for glioblastoma treatment. PMID:25015231

  15. APASS Landolt-Sloan BVgri Photometry of RAVE Stars. I. Data, Effective Temperatures, and Reddenings

    NASA Astrophysics Data System (ADS)

    Munari, U.; Henden, A.; Frigo, A.; Zwitter, T.; Bienaymé, O.; Bland-Hawthorn, J.; Boeche, C.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Kordopatis, G.; Levine, S. E.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G. M.; Siebert, A.; Siviero, A.; Smith, T. C.; Steinmetz, M.; Templeton, M.; Terrell, D.; Welch, D. L.; Williams, M.; Wyse, R. F. G.

    2014-11-01

    We provide AAVSO Photometric All-Sky Survey (APASS) photometry in the Landolt BV and Sloan g'r'i' bands for all 425,743 stars included in the fourth RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as the error of the mean of data obtained and separately calibrated over a median of four distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014, and 0.021 mag for the B, V, g', r', and i' bands, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been ?2 fitted to a densely populated synthetic photometric library designed to widely explore temperature, surface gravity, metallicity, and reddening. Resulting T eff and E B - V , computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process, we find that the reddening caused by a homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for E^{poles}_{B-V} = 0.036 ± 0.002 at the Galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b| >= 25°.

  16. The RSA survey of dwarf galaxies, 1: Optical photometry

    NASA Technical Reports Server (NTRS)

    Vader, J. Patricia; Chaboyer, Brian

    1994-01-01

    We present detailed surface photometry, based on broad B-band charge coupled device (CCD) images, of about 80 dwarf galaxies. Our sample represents approximately 10% of all dwarf galaxies identified in the vicinity of Revised Shapley-Ames (RSA) galaxies on high resolution blue photographic plates, referred to as the RSA survey of dwarf galaxies. We derive global properties and radial surface brightness profiles, and examine the morphologies. The radial surface brightness profiles of dwarf galaxies, whether early or late type, display the same varieties in shape and complexity as those of classical giant galaxies. Only a few are well described by a pure r(exp 1/4) law. Exponential profiles prevail. Features typical of giant disk galaxies, such as exponential profiles with a central depression, lenses, and even, in one case (IC 2041), a relatively prominent bulge are also found in dwarf galaxies. Our data suggest that the central region evolves from being bulge-like, with an r(exp 1/4) law profile, in bright galaxies to a lens-like structure in dwarf galaxies. We prove detailed surface photometry to be a helpful if not always sufficient tool in investigating the structure of dwarf galaxies. In many cases kinematic information is needed to complete the picture. We find the shapes of the surface brightness profiles to be loosely associated with morphological type. Our sample contains several new galaxies with properties intermediate between those of giant and dwarf ellipticals (but no M32-like objects). This shows that such intermediate galaxies exist so that at least a fraction of early-type dwarf ellipticals is structurally related to early-type giants instead of belonging to a totally unrelated, disjunct family. This supports an origin of early-type dwarf galaxies as originally more massive systems that acquired their current morphology as a result of substantial, presumable supernova-driven, mass loss. On the other hand, several early-type dwarfs in our sample are merger candidates. Merger events may lead to anisotropic velocity distributions in systems of any luminosity, including dwarfs. The RSA sample of dwarf galaxies is more likely to contain mergers because, in contrast to earlier dwarf galaxy surveys that have focused on clusters and rich groups of galaxies, the RSA dwarfs are typically located in low density environments. The occurrence of mergers among dwarf galaxies is of interest in connection with the rapid evolution of faint blue galaxy counts at redshift z less than 1 which suggests that dwarf galaxies were about five times more numerous in the recent past. Finally, our sample contains several examples of late-type dwarfs and 'transition' types that are potential precursors of nucleated early-type dwarfs. All the above processes--mass loss, mergers, astration--are likely to have contributed to the formation of the current population of diffuse early-type dwarfs. A few new redshifts of dwarf galaxies are reported in this paper.

  17. A catalogue of IJK photometry of Planetary Nebulae with DENIS

    E-print Network

    S. Schmeja; S. Kimeswenger

    2001-05-15

    Near-infrared photometry of planetary nebulae (PNe) allows the classification of those objects. We present the largest homogeneous sample so far, obtained with the Deep Near Infrared Southern Sky Survey (DENIS).

  18. CCD Photometry of Seven Asteroids at the Belgrade Astronomical Observatory

    NASA Astrophysics Data System (ADS)

    Benishek, Vladimir

    2008-03-01

    CCD photometry of seven asteroids was performed at the Belgrade Astronomical Observatory from July 2006 to August 2007: 78 Diana, 125 Liberatrix, 702 Alauda, 888 Parysatis, 1095 Tulipa, 1293 Sonja, and 2006 VV2.

  19. Shear Wave Velocity Profiles Determined from Surface Wave Measurements at Sites Affected by the August 15th, 2007 Earthquake in Peru

    NASA Astrophysics Data System (ADS)

    Rosenblad, B. L.; Bay, J. A.

    2008-05-01

    The shear wave velocity (Vs) profile of near-surface soils is a critical parameter for understanding recorded ground motions and predicting local site effects in an earthquake. In structural design, the Vs profile in the top 30 m is used to modify design response spectra to account for local soil effects. In addition, knowledge of the near- surface Vs profile at strong motion stations can be used to account for changes in frequency content and amplification caused by the local site conditions. Following the August 15th, 2007 earthquake in Peru, a field testing program was performed to measure Vs profiles in the top 20 to 30 m at twenty-two locations in the affected region. The measurements were performed primarily at the sites of damaged school buildings but were also performed at several strong motion station sites as well as a few locations where evidence of soil liquefaction was observed. Nineteen of the sites were located in the severely affected cities of Chincha, Ica, Pisco and Tambo de Mora, with the remaining three sites located in, Lima, Palpa and Paracus. The Vs profiles were determined from surface wave velocity measurements performed with an impact source. The objective of this paper is to present and discuss the range of Vs profile conditions encountered in the regions affected by the Pisco-Peru earthquake. In the city of Ica, the profiles generally exhibited gradually increasing velocities with depth, with velocities which rarely exceeded 400 m/s in the top 30 m. In contrast, the profiles measured in Pisco, often exhibited strong, shallow velocity contrasts with Vs increasing from less than 200 m/s at the surface to over 600 m/s at some sites. The profiles measured in Chincha generally fell in between the ranges measured in Ica and Pisco. Lastly, soil liquefaction was evident throughout Tambo de Mora on the coast of Peru. Measurements indicated very low shear wave velocities of 75 to 125 m/s in the top 4 m, which is consistent with the observed liquefaction in this region.

  20. Binary Star Synthetic Photometry and Distance Determination Using BINSYN

    NASA Astrophysics Data System (ADS)

    Linnell, Albert P.; DeStefano, Paul; Hubeny, Ivan

    2013-09-01

    This paper extends synthetic photometry to components of binary star systems. The paper demonstrates accurate recovery of single star photometric properties for four photometric standards, Vega, Sirius, GD153, and HD209458, ranging over the HR diagram, when their model synthetic spectra are placed in fictitious binary systems and subjected to synthetic photometry processing. Techniques for photometric distance determination have been validated for all four photometric standards.

  1. BINARY STAR SYNTHETIC PHOTOMETRY AND DISTANCE DETERMINATION USING BINSYN

    SciTech Connect

    Linnell, Albert P. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); DeStefano, Paul [8508B Midvale Ave. North, Seattle, WA 98103 (United States); Hubeny, Ivan, E-mail: linnell@astro.washington.edu, E-mail: pdestefa@uw.edu, E-mail: hubeny@as.arizona.edu [Steward Observatory and Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States)

    2013-09-15

    This paper extends synthetic photometry to components of binary star systems. The paper demonstrates accurate recovery of single star photometric properties for four photometric standards, Vega, Sirius, GD153, and HD209458, ranging over the HR diagram, when their model synthetic spectra are placed in fictitious binary systems and subjected to synthetic photometry processing. Techniques for photometric distance determination have been validated for all four photometric standards.

  2. DOE-EMSP Final Report: Characterization of Changes in Colloid and DNAPL Affecting Surface Chemistry and Remediation

    SciTech Connect

    Susan E. Powers; Stefan J. Grimberg; Miles Denham

    2007-02-07

    The waste disposal to the M-area basin and A-14 outfall at the Savannah River Department of Energy facility in Aiken SC (USA) included a wide variety of inorganic aqueous flows and organic solvents in the form of dense non-aqueous phase liquids (DNAPL). The DNAPL has migrated through the subsurface resulting in widespread groundwater contamination. The goal of this research was to identify and quantify processes that could have affected the migration and remediation of the DNAPL in the subsurface. It was hypothesized that the variety of waste disposed at this site could have altered the mineral, microbial and DNAPL properties at this site relative to other DNAPL sites. The DNAPL was determined to have a very low interfacial tension and is suspected to be distributed in fine grained media, thereby reducing the effectiveness of soil vapor extraction remediation efforts. Although the DNAPL is primarily comprised of tetrachloroethene and trichloroethane, it also contains organic acids and several heavy metals. Experimental results suggest that iron from the aqueous and DNAPL phases undergoes precipitation and dechlorination reactions at the DNAPL-water interface, contributing to the low interfacial tension and acidity of the DNAPL. Biological activity in the contaminated region can also contribute to the low interfacial tension. PCE degrading bacteria produce biosurfactants and adhere to the DNAPL-water interface when stressed by high tetrachloroethene or low dissolved oxygen concentrations. The presence of iron can reduce the interfacial tension by nearly an order of magnitude, while the PCE degraders reduced the interfacial tension by nearly 50%. Abiotic changes in the mineral characteristics were not found to be substantially different between contaminated and background samples. The research completed here begins to shed some insight into the complexities of DNAPL fate and migration at sites where co-disposal of many different waste products occurred. Quantifying the low interfacial tension of the SRS DNAPL helps to formulate a new conceptual picture of the subsurface DNAPL migration and provides an explanation of the limited effectiveness of remediation efforts. Alternative designs for remediation that are more effective for sites with DNAPL in fine grained media are required.

  3. Microlensing for extrasolar planets : improving the photometry

    NASA Astrophysics Data System (ADS)

    Bajek, David J.

    Gravitational Microlensing, as a technique for detecting Extrasolar Planets, is recognised for its potential in discovering small-mass planets similar to Earth, at a distance of a few Astronomical Units from their host stars. However, analysing the data from microlensing events (which statistically rarely reveal planets) is complex and requires continued and intensive use of various networks of telescopes working together in order to observe the phenomenon. As such the techniques are constantly being developed and refined; this project outlines some steps of the careful analysis required to model an event and ensure the best quality data is used in the fitting. A quantitative investigation into increasing the quality of the original photometric data available from any microlensing event demonstrates that 'lucky imaging' can lead to a marked improvement in the signal to noise ratio of images over standard imaging techniques, which could result in more accurate models and thus the calculation of more accurate planetary parameters. In addition, a simulation illustrating the effects of atmospheric turbulence on exposures was created, and expanded upon to give an approximation of the lucky imaging technique. This further demonstrated the advantages of lucky images which are shown to potentially approach the quality of those expected from diffraction limited photometry. The simulation may be further developed for potential future use as a 'theoretical lucky imager' in our research group, capable of producing and analysing synthetic exposures through customisable conditions.

  4. Photometry of resolved galaxies. V - NGC 6822

    NASA Technical Reports Server (NTRS)

    Hoessel, J. G.; Anderson, N.

    1986-01-01

    Three-color CCD frames of the local group irregular galaxy NGC 6822 have been reduced to GRI photometry for 3475 stars using RICHFLD point-spread function fitting techniques. The data are compared with earlier work on this galaxy, particularly with Kayser (1966) on a star-by-star basis. Color-magnitude diagrams are constructed from the data and compared with both theoretical stellar model tracks and the expected foreground star contamination. A luminosity function for the blue stars is derived; comparison of this luminosity function with those of 10 other irregular galaxies indicates that NGC 6822 has a typical young star population. The stellar birthrate and initial mass function are estimated for this galaxy. The slope at the bright end of the mass function looks similar to recent results for the Galaxy, the Magellanic Clouds, and the irregular galaxy Sextans A. NGC 6822 appears to be presently forming stars at a slower rate for its mass than Sextans A or the Magellanic Clouds.

  5. FR Cnc Revisited: Photometry, Polarimetry and Spectroscopy

    E-print Network

    Golovin, A; Hernan-Obispo, M; Andreev, M; Barnes, J R; Montes, D; Pavlenko, E; Pandey, J C; Martinez-Arnaiz, R; Medhi, B J; Parihar, P S; Henden, A; Sergeev, A; Zaitsev, S V; Karpov, N

    2011-01-01

    Here we present the study of FR Cnc, a young, active and spotted star. We performed analysis of ASAS-3 (The All Sky Automated Survey) data for the years 2002-2008 and amended the value of the rotational period to be 0.826518 d. The amplitude of photometric variations decreased abruptly in the year 2005, while the mean brightness remained the same, which was interpreted as a quick redistribution of spots. BVRc and Ic broad band photometric calibration was performed for 166 stars in FR Cnc vicinity. The photometry at Terskol Observatory shows two brightening episodes, one of which occurred at the same phase as the flare of 2006 November 23. Polarimetric BVR observations indicate the probable presence of a supplementary source of polarization. We monitored FR Cnc spectroscopically during the years 2004-2008. We concluded that the RV changes cannot be explained by the binary nature of FR Cnc. We determined the spectral type of FR Cnc as K7V. Calculated galactic space-velocity components (U, V, W) indicate that FR...

  6. Identification of pulsation modes from photometry

    NASA Astrophysics Data System (ADS)

    Breger, Michel

    2014-02-01

    The identification of the detected pulsation modes in terms of the spherical harmonic quantum numbers is crucial for asteroseismology. Light curves obtained in different passbands have become an important tool for mode identifications, which rely on wavelength-dependent amplitudes and phase shifts. We demonstrate this for different types of pulsators and review recent successes from earth-based measurements, especially in determining the important l values. The extensive amount of accurate data needed to determine small phase shifts and accurate amplitude ratios suggests multicolor measurements using space satellites. This motivated the multicolor BRITE satellite project, for which the first two satellites have already been launched successfully. We demonstrate the potential from models computed for the BRITE wavelengths. Most of the excellent presently available satellite photometry is not multicolor, although frequencies with amplitudes as small as a few parts-per-million have been detected and confirmed. We briefly discuss mode identifications from frequency patterns, including the use of correlations between phase and amplitude changes.

  7. The HST Milky Way Stellar Photometry Archive

    NASA Astrophysics Data System (ADS)

    Radburn-Smith, David

    2012-10-01

    The Hubble Legacy Archive has invested a significant effort into automatically generating photometry for point sources in all HST observations regardless of the target. We estimate that this archive contains up to 800,000 Milky Way {MW} stars, distributed across the whole sky, complete to some three magnitudes fainter than SDSS. Approximately half of these stars have color information, which is required for stellar population analysis. This considerable archive is thus in need of collation, analysis, and publication.Here we propose to compile such a catalog for public access and to use it for two science goals: 1} A test of existing MW stellar models, where we will in particular constrain the fainter and more distant stellar populations; and 2} Probe the shape and structure of the MW stellar halo with a deeper star catalog than is currently available. These science cases will be used to fully define the catalog, in particular by assessing the different populations present in the observations, and by assessing the level of noise from contaminants and the completeness of the survey

  8. BVI CCD photometry of 47 Tucanae

    SciTech Connect

    Alcaino, G.; Liller, W.

    1987-08-01

    CCD BVI main-sequence photometry of 47 Tuc is presented, matched to the recent BVI isochrones of VandenBerg and Bell (1985). The main-sequence turnoffs are found to be at V = 17.60 + or - 0.1, B-V = 0.56 + or - 0.02; V-I = 0.68 + or - 0.02, and B-I = 1.24 + or - 0.02. The magnitude difference between the main-sequence turnoff and the horizontal branch is 3.55 + or - 0.15 for all three color indices. A consistent age for 47 Tuc of 17 Gyr and a consistent distance modulus of (m-M)v = 13.2 are obtained for all three indices, and an absolute magnitude of Mv = 0.85 is determined for the horizontal branch stars. The results also favor the adoption of (Fe/H) near -0.5 as the best abundance value for 47 Tuc. 38 references.

  9. Recent Advances in Video Meteor Photometry

    NASA Technical Reports Server (NTRS)

    Swift, Wesley R.; Suggs, Robert M.; Meachem, Terry; Cooke, William J.

    2003-01-01

    One of the most common (and obvious) problems with video meteor data involves the saturation of the output signal produced by bright meteors, resulting in the elimination of such meteors from photometric determinations. It is important to realize that a "bright" meteor recorded by intensified meteor camera is not what would be considered "bright" by a visual observer - indeed, many Generation II or III camera systems are saturated by meteors with a visual magnitude of 3, barely even noticeable to the untrained eye. As the relatively small fields of view (approx.30 ) of the camera systems captures at best modest numbers of meteors, even during storm peaks, the loss of meteors brighter than +3 renders the determination of shower population indices from video observations even more difficult. Considerable effort has been devoted by the authors to the study of the meteor camera systems employed during the Marshall Space Flight Center s Leonid ground-based campaigns, and a calibration scheme has been devised which can extend the useful dynamic range of such systems by approximately 4 magnitudes. The calibration setup involves only simple equipment, available to amateur and professional, and it is hoped that use of this technique will make for better meteor photometry, and move video meteor analysis beyond the realm of simple counts.

  10. NEW UBVRI PHOTOMETRY OF 234 M33 STAR CLUSTERS

    SciTech Connect

    Ma Jun, E-mail: majun@nao.cas.cn [National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing 100012 (China); Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2013-04-15

    This is the second paper of our series. In this paper, we present UBVRI photometry for 234 star clusters in the field of M33. For most of these star clusters, there is photometry in only two bands in previous studies. The photometry of these star clusters is performed using archival images from the Local Group Galaxies Survey, which covers 0.8 deg{sup 2} along the major axis of M33. Detailed comparisons show that, in general, our photometry is consistent with previous measurements, and in particular that our photometry is in good agreement with that of Zloczewski and Kaluzny. Combined with star cluster photometry in previous studies, we present some results: none of the M33 youngest clusters ({approx}10{sup 7} yr) have masses approaching 10{sup 5} M{sub Sun }, and comparisons with models of simple stellar populations suggest a large range of ages for M33 star clusters and some as old as the Galactic globular clusters.

  11. FIXING THE U-BAND PHOTOMETRY OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Krisciunas, Kevin; Bastola, Deepak; Suntzeff, Nicholas B. [Department of Physics and Astronomy, Texas A and M University, 4242 TAMU, College Station, TX 77843-4242 (United States); Espinoza, Juan; Gonzalez, David [Cerro Tololo Inter-American Observatory, Casilla 603, La Serena (Chile); Gonzalez, Luis; Gonzalez, Sergio; Hsiao, Eric Y.; Morrell, Nidia; Phillips, Mark M. [Las Campanas Observatory, Casilla 601, La Serena (Chile); Hamuy, Mario, E-mail: krisciunas@physics.tamu.edu, E-mail: suntzeff@physics.tamu.edu, E-mail: jespinoza@ctio.noao.edu, E-mail: hsiao@lco.cl, E-mail: nmorrell@lco.cl, E-mail: mmp@lco.cl, E-mail: mhamuy@das.uchile.cl [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile)

    2013-01-01

    We present previously unpublished photometry of supernovae 2003gs and 2003hv. Using spectroscopically derived corrections to the U-band photometry, we reconcile U-band light curves made from imagery with the Cerro Tololo 0.9 m, 1.3 m, and Las Campanas 1 m telescopes. Previously, such light curves showed a 0.4 mag spread at one month after maximum light. This gives us hope that a set of corrected ultraviolet light curves of nearby objects can contribute to the full utilization of rest-frame U-band data of supernovae at redshift {approx}0.3-0.8. As pointed out recently by Kessler et al. in the context of the Sloan Digital Sky Survey supernova search, if we take the published U-band photometry of nearby Type Ia supernovae at face value, there is a 0.12 mag U-band anomaly in the distance moduli of higher redshift objects. This anomaly led the Sloan survey to eliminate from their analyses all photometry obtained in the rest-frame U-band. The Supernova Legacy Survey eliminated observer frame U-band photometry, which is to say nearby objects observed in the U-band, but they used photometry of high-redshift objects no matter in which band the photons were emitted.

  12. Reliability, Validity, and Responsiveness to Change of the Patient Report of Extent of Psoriasis Involvement (PREPI) for Measuring Body Surface Area Affected by Psoriasis

    PubMed Central

    Dommasch, E. D.; Shin, D. B.; Troxel, A. B.; Margolis, D. J.; Gelfand, J. M.

    2010-01-01

    Background The development of a simple, reliable, valid, and responsive method for measuring the extent of skin involvement in psoriasis is important for use in epidemiologic studies. Objectives We sought to investigate the psychometric characteristics of the Patient Report of Extent of Psoriasis Involvement (PREPI), a single-question method for measuring body surface area affected by psoriasis. Patients/Methods This was a cross-sectional study of 140 psoriasis patients with an exploratory prospective longitudinal cohort component. Reliability was measured via a test-retest approach and criterion validity was investigated by comparing the patients’ PREPI to an assessment of body surface area of involvement by a dermatologist. We additionally compared Skindex-29 scores to the PREPI. To demonstrate responsiveness and establish a minimally important difference in the PREPI, we created receiver operating characteristic curves for the PREPI instrument. Results The test-retest reliability of the PREPI was nearly perfect (ICC = 0.99, 95% CI: 0.97, 0.99), and there was substantial agreement between patient and physician assessments (ICC = 0.82, 95% CI: 0.75, 0.87). The PREPI showed significant correlations with all Skindex-29 domains. We found the PREPI to be responsive to change and identified changes in the PREPI score that have good discrimination between patients with and without a minimally important clinical difference. Conclusion Our study suggests that the PREPI is a reliable, valid, and responsive measure of body surface area affected by psoriasis that may be useful for future epidemiologic research. PMID:19906216

  13. Monocyte proliferation and differentiation to osteoclasts is affected by density of collagen covalently bound to a poly(dimethyl siloxane) culture surface.

    PubMed

    Shafieyan, Yousef; Tiedemann, Kerstin; Goulet, Andrew; Komarova, Svetlana; Quinn, Thomas M

    2012-06-01

    Osteoclast differentiation is affected by substrate characteristics and environmental conditions; these parameters are therefore of interest for understanding bone remodeling. As a step toward osteoclast mechanotransduction experiments, we aimed to optimize conditions for osteoclast differentiation on extendable poly(dimethylsiloxane) (PDMS) substrates. Because cells attach poorly on PDMS alone, chemical modification by covalent attachment of collagen type I was performed. Effects of collagen surface concentrations on monocyte fusion and osteoclast differentiation were examined. Osteoclasts differentiated on modified PDMS were fewer in number (by ?50%) than controls on polystyrene physically modified by nonspecific attachment of collagen, and exhibited somewhat different morphologies. Nevertheless, for certain choices of the chemical modification procedures, appropriate differentiation on PDMS was still evident by qRT-PCR analysis for tartrate-resistant acid phosphate (TRAP) and cathepsin K (CTSK) gene expression, positive TRAP staining, fluorescent phalloidin staining showing actin ring formation and bone resorption assays. At relatively high collagen surface densities, monocyte clumps appeared on PDMS suggesting substrate-induced alterations to monocyte fusion. Covalently bound collagen can therefore be used to promote osteoclast differentiation on extendable PDMS substrates. Under appropriate conditions osteoclasts retain similar functionality as on polystyrene, which will enable future studies of osteoclast interactions with microstructured surfaces and mechanostimulation. PMID:22447405

  14. VizieR Online Data Catalog: Galaxies morphology and IR photometry III. (Gavazzi+, 2000)

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Franzetti, P.; Scodeggio, M.; Boselli, A.; Pierini, D.; Baffa, C.; Lisi, F.; Hunt, L. K.

    1999-11-01

    We present near-infrared H-band (1.65?m) surface photometry of 558 galaxies in the Coma Supercluster and in the Virgo cluster. This data set, obtained with the Arcetri NICMOS3 camera ARNICA mounted on the Gornergrat Infrared Telescope, is aimed at complementing, with observations of mostly early-type objects, our NIR survey of spiral galaxies in these regions, presented in previous papers of this series. Magnitudes at the optical radius, total magnitudes, isophotal radii and light concentration indices are derived. We confirm the existence of a positive correlation between the near-infrared concentration index and the galaxy H-band luminosity (2 data files).

  15. Dithering Strategies and Point-Source Photometry

    SciTech Connect

    Samsing, Johan; Kim, Alex G

    2011-02-22

    The accuracy in the photometry of a point source depends on the point-spread function (PSF), detector pixelization, and observing strategy. The PSF and pixel response describe the spatial blurring of the source, the pixel scale describes the spatial sampling of a single exposure, and the observing strategy determines the set of dithered exposures with pointing offsets from which the source flux is inferred. In a wide-field imaging survey, sources of interest are randomly distributed within the field of view and hence are centered randomly within a pixel. A given hardware configuration and observing strategy therefore have a distribution of photometric uncertainty for sources of fixed flux that fall in the field. In this article we explore the ensemble behavior of photometric and position accuracies for different PSFs, pixel scales, and dithering patterns. We find that the average uncertainty in the flux determination depends slightly on dither strategy, whereas the position determination can be strongly dependent on the dithering. For cases with pixels much larger than the PSF, the uncertainty distributions can be non-Gaussian, with rms values that are particularly sensitive to the dither strategy. We also find that for these configurations with large pixels, pointings dithered by a fractional pixel amount do not always give minimal average uncertainties; this is in contrast to image reconstruction for which fractional dithers are optimal. When fractional pixel dithering is favored, a pointing accuracy of better than {approx}0.15 {approx}0.15 pixel width is required to maintain half the advantage over random dithers.

  16. Surface Orientation Affects the Direction of Cone Growth by Leptolyngbya sp. Strain C1, a Likely Architect of Coniform Structures Octopus Spring (Yellowstone National Park)

    PubMed Central

    Reyes, Kristina; Gonzalez, Nicolas I.; Stewart, Joshua; Ospino, Frank; Nguyen, Dickie; Cho, David T.; Ghahremani, Nahal; Spear, John R.

    2013-01-01

    Laminated, microbially produced stromatolites within the rock record provide some of the earliest evidence for life on Earth. The chemical, physical, and biological factors that lead to the initiation of these organosedimentary structures and shape their morphology are unclear. Modern coniform structures with morphological features similar to stromatolites are found on the surface of cyanobacterial/microbial mats. They display a vertical element of growth, can have lamination, can be lithified, and observably grow with time. To begin to understand the microbial processes and interactions required for cone formation, we determined the phylogenetic composition of the microbial community of a coniform structure from a cyanobacterial mat at Octopus Spring, Yellowstone National Park, and reconstituted coniform structures in vitro. The 16S rRNA clone library from the coniform structure was dominated by Leptolyngbya sp. Other cyanobacteria and heterotrophic bacteria were present in much lower abundance. The same Leptolyngbya sp. identified in the clone library was also enriched in the laboratory and could produce cones in vitro. When coniform structures were cultivated in the laboratory, the initial incubation conditions were found to influence coniform morphology. In addition, both the angle of illumination and the orientation of the surface affected the angle of cone formation demonstrating how external factors can influence coniform, and likely, stromatolite morphology. PMID:23241986

  17. CP2 stars in clusters: deep Delta a-photometry

    E-print Network

    H. M. Maitzen; M. Rode; E. Paunzen

    1998-05-05

    The search for chemically peculiar (CP) stars in open clusters using photoelectric photometry sampling the presence of the characteristic flux depression feature at 5200A via the Delta a-system (Maitzen 1976) has so far delivered data for objects usually no more distant than 1000 pc from the Sun. If one intends to study the presence of CP stars at larger distances from the Sun, classical photometry has to be replaced by CCD photometry. For the first time, our investigation presents the results of CCD-photometry in the Delta a-system for a rich open cluster which is at a distance clearly beyond hitherto studied objects, Melotte 105 (2 kpc, log age = 8.5). Comparison with published uvby-photometry yields the calibration of the colour index g_1-y of our system, which is necessary for deriving the peculiarity index Delta a. For this we achieve an average accuracy of 0.007 mag. Six objects with only marginally peculiar Delta a-values were found, but spectroscopic and additional photometric evidence is needed to substantiate their peculiarity.

  18. Revised Filter Profiles and Zero Points for Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Mann, Andrew W.; von Braun, Kaspar

    2015-02-01

    Estimating accurate bolometric fluxes for stars requires reliable photometry to absolutely flux calibrate the spectra. This is a significant problem for studies of very bright stars, which are generally saturated in modern photometric surveys. Instead we must rely on photometry with less precise calibration. We utilize precisely flux-calibrated spectra to derive improved filter bandpasses and zero points for the most common sources of photometry for bright stars. In total, we test 39 different filters in the General Catalog of Photometric Data as well as those from Tycho-2 and Hipparcos. We show that utilizing inaccurate filter profiles from the literature can create significant color terms resulting in fluxes that deviate by ?10% from actual values. To remedy this we employ an empirical approach; we iteratively adjust the literature filter profile and zero point, convolve it with catalog spectra, and compare to the corresponding flux from the photometry. We adopt the passband values that produce the best agreement between photometry and spectroscopy and are independent of stellar color. We find that while most zero points change by < 5%, a few systems change by 10-15%. Our final profiles and zero points are similar to recent estimates from the literature. Based on determinations of systematic errors in our selected spectroscopic libraries, we estimate that most of our improved zero points are accurate to 0.5-1%.

  19. First time-series optical photometry from Antarctica

    E-print Network

    K. G. Strassmeier; R. Briguglio; T. Granzer; G. Tosti; I. DiVarano; I. Savanov; M. Bagaglia; S. Castellini; A. Mancini; G. Nucciarelli; O. Straniero; E. Distefano; S. Messina; G. Cutispoto

    2008-07-18

    Beating the Earth's day-night cycle is mandatory for long and continuous time-series photometry and had been achieved with either large ground-based networks of observatories at different geographic longitudes or when conducted from space. A third possibility is offered by a polar location with astronomically-qualified site characteristics. Aims. In this paper, we present the first scientific stellar time-series optical photometry from Dome C in Antarctica and analyze approximately 13,000 CCD frames taken in July 2007. We conclude that high-precision CCD photometry with exceptional time coverage and cadence can be obtained at Dome C in Antarctica and be successfully used for time-series astrophysics.

  20. Fixing the U-band Photometry of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Krisciunas, Kevin; Bastola, Deepak; Espinoza, Juan; Gonzalez, David; Gonzalez, Luis; Gonzalez, Sergio; Hamuy, Mario; Hsiao, Eric Y.; Morrell, Nidia; Phillips, Mark M.; Suntzeff, Nicholas B.

    2013-01-01

    We present previously unpublished photometry of supernovae 2003gs and 2003hv. Using spectroscopically derived corrections to the U-band photometry, we reconcile U-band light curves made from imagery with the Cerro Tololo 0.9 m, 1.3 m, and Las Campanas 1 m telescopes. Previously, such light curves showed a 0.4 mag spread at one month after maximum light. This gives us hope that a set of corrected ultraviolet light curves of nearby objects can contribute to the full utilization of rest-frame U-band data of supernovae at redshift ~0.3-0.8. As pointed out recently by Kessler et al. in the context of the Sloan Digital Sky Survey supernova search, if we take the published U-band photometry of nearby Type Ia supernovae at face value, there is a 0.12 mag U-band anomaly in the distance moduli of higher redshift objects. This anomaly led the Sloan survey to eliminate from their analyses all photometry obtained in the rest-frame U-band. The Supernova Legacy Survey eliminated observer frame U-band photometry, which is to say nearby objects observed in the U-band, but they used photometry of high-redshift objects no matter in which band the photons were emitted. Based in part on observations taken at the Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

  1. The Impact of the Hepatitis B Virus Polymerase rtA181T Mutation on Replication and Drug Resistance Is Potentially Affected by Overlapping Changes in Surface Gene

    PubMed Central

    Ahn, Sung Hyun; Park, Yong Kwang; Park, Eun-Sook; Kim, Jeong Han; Kim, Doo Hyun; Lim, Keo-Heun; Jang, Moon Sun; Choe, Won Hyeok; Ko, Soon Young; Sung, In-Kyung; Kwon, So Young

    2014-01-01

    ABSTRACT The emergence of drug-resistant hepatitis B virus (HBV) is a major problem for antiviral treatment in chronic hepatitis B infection. In this study, we analyzed the evolution of drug-resistant mutations and characterized the effects of the rtA181T and rtI233V mutations on viral replication and drug resistance. We performed a clonal analysis of the HBV polymerase gene from serum samples during viral breakthrough treated with antiviral agents. A series of mutant clones containing rtA181T and/or rtI233V mutations were constructed and determined the effect of these mutations on the replication ability and drug resistance. An in vitro study revealed that the effect of the rtA181T mutation on viral replication and drug resistance is dependent on the mutations in the overlapping surface gene. Compared to the rtA181T surface missense mutation (rtA181T/sW172S), the introduction of rtA181T surface nonsense mutation (rtA181T/sW172*) resulted in decreased viral replication and increased drug resistance. Complementation assay revealed that the truncated PreS1 is responsible for reduced replication of rtA181T/sW172* mutant. Moreover, the rtA181T/sW172* mutant exhibited a defect in viral particle secretion. The rtI233V mutation that emerged during adefovir therapy reduced viral replication and conferred resistance to adefovir. Our data suggest that the impact of the rtA181T mutation on replication and drug resistance differs based on the mutation status of the corresponding surface gene. The rtI233V mutation also affects replication ability and drug resistance. This observation suggests the need for genotypic analysis of overlapping surface genes to manage antiviral drug resistance if clinical isolates harbor the rtA181T mutation. IMPORTANCE The emergence of drug-resistant HBV that are no longer susceptible to nucleos(t)ide analogues is a major problem for antiviral treatment in chronic hepatitis B infection. Among drug-resistant mutations, the single rtA181T mutation is known to confer cross-resistance to antiviral drugs. This mutation causes intermediate or reduced susceptibility to tenofovir. Moreover, the clinical occurrence of the rtA181T mutation during antiviral therapy is also high. Our study revealed that the effect of the rtA181T mutation on viral replication and drug resistance is dependent on the mutations in the overlapping surface gene. This observation suggests the need for genotypic analysis of overlapping surface genes to manage antiviral drug resistance if clinical isolates harbor the rtA181T mutation. We believe that our study will not only extend the understanding of the drug resistance mechanism, but it will also ultimately provide new treatment options for patients with multidrug resistant HBV. PMID:24696492

  2. HUBBLE SPACE TELESCOPE Photometry of the Globular Cluster M4

    NASA Astrophysics Data System (ADS)

    Ibata, Rodrigo A.; Richer, Harvey B.; Fahlman, Gregory G.; Bolte, Michael; Bond, Howard E.; Hesser, James E.; Pryor, Carlton; Stetson, Peter B.

    1999-02-01

    This paper presents a detailed description of the acquisition and processing of a large body of imaging data for three fields in the globular cluster M4 taken with the Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope. Analysis with the ALLFRAME package yielded the deepest photometry yet obtained for this cluster. The resulting data set for 4708 stars (positions and calibrated photometry in V, I, and, in two fields, U) spanning approximately six cluster core radii is presented. The scientific analysis is deferred to three companion papers, which investigate the significant white dwarf population discovered and the main-sequence population.

  3. Transit and secondary eclipse photometry in the near-infrared

    E-print Network

    Ignas Snellen

    2007-05-02

    Near-infrared photometry of transiting extrasolar planets can be of great scientific value. It is however not straightforward to reach the necessary millimagnitude precision. Here we report on our attempts to observe transits and secondary eclipses of several extrasolar planets at 2.2 micron. Best results have been obtained on OGLE-TR-113b using the SOFI near-infrared camera on ESO's New Technology Telescope. Its K-band transit shows a remarkably flat bottom indicating low stellar limb darkening. Secondary eclipse photometry has resulted in a formal 3 sigma detection, but residual systematic effects make this detection rather uncertain.

  4. Characterization of transiting exoplanets by way of differential photometry

    NASA Astrophysics Data System (ADS)

    Cowley, Michael; Hughes, Stephen

    2014-05-01

    This paper describes a simple activity for plotting and characterizing the light curve from an exoplanet transit event by way of differential photometry analysis. Using free digital imaging software, participants analyse a series of telescope images with the goal of calculating various exoplanet parameters, including size, orbital radius and habitability. The activity has been designed for a high-school or undergraduate university level and introduces fundamental concepts in astrophysics and an understanding of the basis for exoplanetary science, the transit method and digital photometry.

  5. Retrieval of cirrus properties by Sun photometry: A new perspective on an old issue

    E-print Network

    Baum, Bryan A.

    Retrieval of cirrus properties by Sun photometry: A new perspective on an old issue Michal Segal. Ramachandran, J. Redemann, and B. A. Baum (2013), Retrieval of cirrus properties by Sun photometry: A new

  6. Affective Domain

    NSDL National Science Digital Library

    The affective domain can significantly enhance, inhibit or even prevent student learning. The affective domain includes factors such as student motivation, attitudes, perceptions and values. Teachers can increase their effectiveness by considering the affective domain in planning courses, delivering lectures and activities, and assessing student learning. This module contains information and resources for incorporating the affective domain into teaching.

  7. Multicolor photometry of x ray selected Abell clusters

    NASA Technical Reports Server (NTRS)

    Lopez-Cruz, Omar

    1993-01-01

    Strong evidence of evolution in cluster of galaxies at relatively low redshift has been indicated by recent x-ray studies. We are conducting a comprehensive optical study of a sample of Abell clusters that are strong x-ray emitters in order to test the x-ray evolution scenarios that have been proposed. The initial observations consist of three-color (B, R, I) imaging of low-redshift (0.025 less than z less than 0.25) Abell clusters using the T2KA CCD on the 0.9m telescope at KPNO the large field (23 ft. x 23 ft., approx. 1 Mpc at z = 0.025 and approx. 7 Mpc at z = 0.25) gives the unprecedented ability to sample most of the extent of the field of low-redshift clusters using a CCD. Given the advantages of CCDs over photographic plates, we expect to improve on many of the previous studies. A list of x-ray selected cluster of galaxies provides a homogeneous sample of true clusters that cannot be mistaken from apparent over-densities due to projection effects of field galaxies. Some optical indicators of cluster evolution are the population of ratios of cluster galaxies and their spatial distribution, a regular spiral-poor cluster is expected to be more evolved than an irregular spiral-rich cluster. Also regular spiral-poor clusters present high central concentrations while irregular spiral-rich are less concentrated. Variations in the Luminosity Function (LF) can indicate evolution. But in order to build reliable LFs it is necessary to determine the Hubble types of the cluster galaxies. In the past the classifications of cluster galaxies have been done by visual inspection on photographic material, this technique is very limited and can lead to errors when the galaxies are faint. The Hubble types of cluster galaxies can be determined in an objective manner by comparing colors and profiles from surface photometry. To show that this approach is feasible, I have presented preliminary results from the photometric analysis of the Abell-cluster A1213. Colors and profiles of the surface brightness distribution were compared to determine the Hubble types of the cluster galaxies.

  8. Infrared space observatory photometry of circumstellar dust in Vega-type systems

    NASA Technical Reports Server (NTRS)

    Fajardo-Acosta, S. B.; Stencel, R. E.; Backman, D. E.; Thakur, N.

    1998-01-01

    The ISOPHOT (Infrared Space Observatory Photometry) instrument onboard the Infrared Space Observatory (ISO) was used to obtain 3.6-90 micron photometry of Vega-type systems. Photometric data were calibrated with the ISOPHOT fine calibration source 1 (FCS1). Linear regression was used to derive transformations to make comparisons to ground-based and IRAS photometry systems possible. These transformations were applied to the photometry of 14 main-sequence stars. Details of these results are reported on.

  9. Flight Investigation on a Fighter-type Airplane of Factors which Affect the Loads and Load Distributions on the Vertical Tail Surfaces During Rudder Kicks and Fishtails

    NASA Technical Reports Server (NTRS)

    Boshar, John

    1947-01-01

    Results are presented of a flight investigation conducted on a fighter-type airplane to determine the factors which affect the loads and load distributions on the vertical tail surfaces in maneuvers. An analysis is made of the data obtained in steady flight, rudder kicks, and fishtail maneuvers. For the rudder kicks, the significant loads were the "deflection load" resulting from an abrupt control deflection and the "dynamic load" consisting of a load corresponding to the new static equilibrium condition for the rudder deflected plus a load due to a transient overshoot. The minimum time to reach the maximum control deflection attainable by the pilot in any flight condition was found to be a constant. In the fishtail maneuvers, it was found that the pilot tends to deflect the rudder in phase with the natural frequency of the airplane. The maximum loads measured in fishtails were of the same order of magnitude as those from a rudder kick in which the rudder is returned to zero at the time of maximum sideslip.

  10. Platelet CD36 surface expression levels affect functional responses to oxidized LDL and are associated with inheritance of specific genetic polymorphisms

    PubMed Central

    Ghosh, Arunima; Murugesan, Gurunathan; Chen, Kan; Zhang, Li; Wang, Qing; Febbraio, Maria; Anselmo, Rita Marie; Marchant, Kandice; Barnard, John

    2011-01-01

    CD36 modulates platelet function via binding to oxidized LDL (oxLDL), cell-derived microparticles, and thrombospondin-1. We hypothesized that the level of platelet CD36 expression may be associated with inheritance of specific genetic polymorphisms and that this would determine platelet reactivity to oxLDL. Analysis of more than 500 subjects revealed that CD36 expression levels were consistent in individual donors over time but varied widely among donors (200-14 000 molecules per platelet). Platelet aggregometry and flow cytometry in a subset of subjects with various CD36 expression levels revealed a high level of correlation (r2 = 0.87) between platelet activation responses to oxLDL and level of CD36 expression. A genome-wide association study of 374 white subjects from the Cleveland Clinic ASCLOGEN study showed strong associations of single nucleotide polymorphisms in CD36 with platelet surface CD36 expression. Most of these findings were replicated in a smaller subset of 25 black subjects. An innovative gene-based genome-wide scan provided further evidence that single nucleotide polymorphisms in CD36 were strongly associated with CD36 expression. These studies show that CD36 expression on platelets varies widely, correlates with functional responses to oxLDL, and is associated with inheritance of specific CD36 genetic polymorphisms, and suggest that inheritance of specific CD36 polymorphisms could affect thrombotic risk. PMID:21478428

  11. Optical properties of boreal forest fire smoke derived from Sun photometry

    E-print Network

    Li, Zhanqing

    Optical properties of boreal forest fire smoke derived from Sun photometry N. T. O'Neill,1 T. F 2001; published 13 June 2002. [1] Aerosol optical properties derived from Sun photometry were: Aerosols (0305); KEYWORDS: aerosols, forest fire smoke, Sun photometry, optics 1. Introduction [2] Smoke

  12. NOVEL METHODS FOR PREDICTING PHOTOMETRIC REDSHIFTS FROM BROADBAND PHOTOMETRY USING VIRTUAL SENSORS

    E-print Network

    NOVEL METHODS FOR PREDICTING PHOTOMETRIC REDSHIFTS FROM BROADBAND PHOTOMETRY USING VIRTUAL SENSORS, and the Two Micron All Sky Survey using two new training-set methods. We utilize the broadband photometry from material: color figures 1. INTRODUCTION Using broadband photometry in multiple filters to estimate

  13. New Aperture and PSF Photometry QSO 0957+561A,B

    E-print Network

    Ovaldsen, Jan-Erik

    New Aperture and PSF Photometry of QSO 0957+561A,B Application to Time Delay and Microlensing Aperture and PSF Photometry of QSO 0957+561A,B", is distributed under the terms of the Public Library was initiated with the aim of developing a photometry program to reduce the CCD frames. The results were

  14. An Improved Technique for the Photometry and Astrometry of Faint Companions

    E-print Network

    Dainty, Chris

    An Improved Technique for the Photometry and Astrometry of Faint Companions DANIEL BURKE School to differential astrometry and photometry of faint companions in adap- tive optics images. It is based ratio (SR) data (SR 0:5), the differential photometry of a binary star with a m ¼ 4:5 and a separation

  15. Aperture Photometry in Practice AST337 In-Class Exercise (hand me in before you leave!)

    E-print Network

    Lowenthal, James D.

    Aperture Photometry in Practice AST337 In-Class Exercise (hand me in before you leave!) 7 April in pixels, its brightness in ADU ("Object Counts" in "atv aperture photometry" window), its FWHM in pixels FWHM (ie. aperture radius = FWHM)? Part III: PhotVis, an IDL Photometry and Visualization Tool 1. Run

  16. Notes for KINGFISH on SPIRE Photometry DRAFT: v8 2013.3.16.759

    E-print Network

    Draine, Bruce T.

    Notes for KINGFISH on SPIRE Photometry DRAFT: v8 2013.3.16.759 B. T. Drainea ABSTRACT Some notes on interpretation of SPIRE photometry of extended sources, and recommendations for use by the KINGFISH collaboration photometry to be sometimes confusing: the distinction between beam sizes to use for point sources or extended

  17. ON THE AGE AND METALLICITY ESTIMATION OF SPIRAL GALAXIES USING OPTICAL AND NEAR-INFRARED PHOTOMETRY

    E-print Network

    Lee, Hyun-chul

    ON THE AGE AND METALLICITY ESTIMATION OF SPIRAL GALAXIES USING OPTICAL AND NEAR-INFRARED PHOTOMETRY-infrared photometry show surprisingly orthogonal grids as age and metallicity are varied, and they are coming headinggs: galaxies: abundances -- galaxies: evolution -- galaxies: photometry -- galaxies: spiral

  18. Comet Kohoutek. [proceedings - astronomical photometry/astronomical spectroscopy

    NASA Technical Reports Server (NTRS)

    Gary, G. A. (editor)

    1975-01-01

    A compilation of scientific observations (workshop) is presented. Topics discussed are: (1) tail form, structure, and evolution; (2) hydroxyl related observations; (3) molecules and atoms in the coma and tail; (4) photometry and radiometry; and (5) spacecraft and ground based observation data. Color photographs are shown.

  19. Photometry of Standard Stars and Open Star Clusters

    NASA Astrophysics Data System (ADS)

    Jefferies, Amanda; Frinchaboy, Peter

    2010-10-01

    Photometric CCD observations of open star clusters and standard stars were carried out at the McDonald Observatory in Fort Davis, Texas. This data was analyzed using aperture photometry algorithms (DAOPHOT II and ALLSTAR) and the IRAF software package. Color-magnitude diagrams of these clusters were produced, showing the evolution of each cluster along the main sequence.

  20. Characterization of Transiting Exoplanets by Way of Differential Photometry

    ERIC Educational Resources Information Center

    Cowley, Michael; Hughes, Stephen

    2014-01-01

    This paper describes a simple activity for plotting and characterizing the light curve from an exoplanet transit event by way of differential photometry analysis. Using free digital imaging software, participants analyse a series of telescope images with the goal of calculating various exoplanet parameters, including size, orbital radius and…

  1. Characterizing New Eclipsing Binaries Identified from STEREO Photometry

    NASA Astrophysics Data System (ADS)

    Markov, Harry; Tsvetanov, Zlatan; Iliev, Ilian; Stateva, Ivanka; Markova, Nevena

    2012-04-01

    Since 2010, a program to explore new eclipsing binary systems identified from STEREO photometry has been in progress. Our first results are presented here: light curves and high resolution spectra taken with Coudé spectrograph (National Astronomical Observatory Rozhen) and ARC Échelle spectrometer (ARCES, Apache Point Observatory).

  2. Crab Pulsar Photometry and the Signature of Free Precession

    E-print Network

    Andrej Cadez; Simon Vidrih; Mirjam Galicic; Alberto Carraminana

    2003-03-17

    Optical photometry for the pulsar PSR0531+21 has been extended with new observations that strengthen evidence for a previously observed 60 seconds periodicity. This period is found to be increasing with time at approximately the same rate as the rotational period of the pulsar. The observed period and its time dependence fit a simple free precession model.

  3. Error analysis of multi-wavelength sun photometry

    Microsoft Academic Search

    Glenn E. Shaw

    1976-01-01

    The error terms involved in precision multi-wavelength sun photometry, as used to study atmospheric aerosols, are analyzed. The error terms treated include instrumental errors, calibration errors, and errors imposed by the atmosphere. It is shown that in order to derive accurate aerosol parameters, one must exercise great care in the photometer calibration. A procedure for accurate calibration is described, based

  4. uvby--beta photoelectric photometry of NGC 7063

    E-print Network

    J. H. Pena; L. Fox Machado; R. Garrido

    2007-07-15

    From uvby photometry of 75 stars in the direction of NGC 7063 we were able to determine membership of some stars and fix the distance (722 +- 105 pc), log age (of 8.146) and reddening (E(b-y) = 0.091 +- 0.039 mag) for the cluster.

  5. CCD Photometry of Nova V1500 Cygni Twenty Years After

    E-print Network

    I. Semeniuk; A. Olech; M. Nalezyty

    1995-12-14

    We report on CCD photometry of Nova V1500 Cygni obtained in July 1995 to show that twenty years after outburst, being of about 18~mag, the star can still be observed with small telescopes. The 0.1396 day period continues to be stable.

  6. Iontophoresis and Flame Photometry: A Hybrid Interdisciplinary Experiment

    ERIC Educational Resources Information Center

    Sharp, Duncan; Cottam, Linzi; Bradley, Sarah; Brannigan, Jeanie; Davis, James

    2010-01-01

    The combination of reverse iontophoresis and flame photometry provides an engaging analytical experiment that gives first-year undergraduate students a flavor of modern drug delivery and analyte extraction techniques while reinforcing core analytical concepts. The experiment provides a highly visual demonstration of the iontophoresis technique and…

  7. JCMT COADD: UKT14 continuum and photometry data reduction

    NASA Astrophysics Data System (ADS)

    Hughes, David; Oliveira, Firmin J.; Tilanus, Remo P. J.; Jenness, T.

    2014-11-01

    COADD was used to reduce photometry and continuum data from the UKT14 instrument on the James Clerk Maxwell Telescope in the 1990s. The software can co-add multiple observations and perform sigma clipping and Kolmogorov-Smirnov statistical analysis. Additional information on the software is available in the JCMT Spring 1993 newsletter (large PDF).

  8. A Laboratory of Photometry and Radiometry of Light Pollution (LPLAB)

    Microsoft Academic Search

    P. Cinzano

    2003-01-01

    We present the Laboratory of Photometry and Radiometry of Light Pollution (LPLAB) that we set up to provide the Light Pollution Science and Technology Institute (ISTIL) of instruments and calibration services to support its scientific and technological research on light pollution and related environmental effects. The laboratory equipments are characterized by low light intensity measurement and calibration capabilities and by

  9. Empirical color transformations between SDSS photometry and other photometric systems

    Microsoft Academic Search

    Katrin Jordi; E. K. Grebel; Karin Ammon

    2006-01-01

    Aims.We present empirical color transformations between the Sloan Digital Sky Survey (SDSS) ugriz photometry and the Johnson-Cousins UBVRI system and Becker's RGU system, respectively. Owing to the magnitude of data that is becoming available in the SDSS photometric system it is particularly important to be able to convert between this new system and traditional photometric systems. Unlike earlier published transformations

  10. Photometry and Coravel observations of IC 2488 (Claria+, 2003)

    Microsoft Academic Search

    J. J. Claria; A. E. Piatti; E. Lapasset; J.-C. Mermilliod

    2002-01-01

    We present new UBV photoelectric observations of 119 stars in the field of the southern open cluster IC 2488, supplemented by DDO and Washington photometry and Coravel radial velocities for a sample of red giant candidates. Nearly 50% of the stars sampled - including three red giants and one blue straggler - are found to be probable cluster members. Photometric

  11. Astrometry and Photometry of Asteroids and Comets Detected by WISE

    Microsoft Academic Search

    Robert S. McMillan; Amy Mainzer; Jeff Larsen; Jim Scotti; Joe Masiero; James Bauer; Tommy Grav; Chet Maleszewski

    2011-01-01

    Telescope time is requested to recover and do astrometry and photometry of carefully selected asteroids, comets, and suspected comets previously detected by WISE. The WISE all-sky thermal infrared survey uncovered more solar system objects with dark albedos and more objects with comet-like orbital elements than expected. These outliers may represent hitherto unexplored populations and may reveal characteristics of the evolution

  12. High Speed Photometry of the Transiting Planet HD 209458b

    NASA Astrophysics Data System (ADS)

    Schultz, Alfred

    2001-07-01

    HD 209458b is the only extrasolar giant planet {EGP} detected that has an orbit inclined enough toward the Sun for the transits to be detected. Differential photometry of HD 209458 with respect to comparison stars showed a transit depth of 1.5 a transit time of 3.2 hours. Transit ingress and egress are 25 minutes in duration suggesting the planet transits along a short chord instead of the full stellar disk. We propose to observe the transit ingress {1-orbit} and egress {1-orbit} with a Fine Guidance Sensor {FGS} used as a high- speed photometer {40 Hz}. An FGS can be used to obtain relative photometry with better than milli-mag accuracy and one-minute time resolution. FGS photometry of the ingress and egress will allow an independent determination of the planet radius and the inclination of the orbit. We also propose to observe the ingress and egress at least five times during Cycle 10 {10 orbits requested} to determine any variability of transit times that would indicate precession of the orbit caused by secondary bodies in the HD 209458 system. As a secondary goal, we will search for structure in the photometry that would indicate the presence of planetary satellites.

  13. Readmefirst_planetary_photometry_data Purpose of this archive

    E-print Network

    Lockwood, Wes

    b ,y photometry of Uranus, Neptune, and Saturn's satellite Titan. While nearly all the data (except_by_season.txt and subsidiary files: Titan_nights.txt Titan_summary.txt Uranus_by_season.txt and subsidiary files: Uranus_nights.txt Uranus_summary.txt Neptune_by_season.txt and subsidiary files: Neptune_nights.txt Neptune _summary

  14. Application Note (A14) A guide to photometry and

    E-print Network

    Johnsen, Sönke

    .3.4. Stray Light 1.3.5. Blocking Filters 1.3.6. Grating Optimization 1.3.7. Detectors 1.3.8. Signal Detection, Systematic and Periodic errors 1.7.2. Error Sources Photometry and Spectroradiometry #12;#12;1 1 radiant energy emitted by the radiating source over the entire optical spectrum (1 nm to 1000 µm

  15. Karl Schwarzschild's investigations of ``out-of-focus photometry'' between 1897-1899 and his contribution to photographic photometry

    Microsoft Academic Search

    Peter Habison

    1999-01-01

    From 1897 to 1899 Karl Schwarzschild was working at Kuffner Observatory in Vienna. During these years he developed new measuring techniques in the field of photographic photometry, where he particularly studied the quantitative determination of the departure of the reciprocity law during photographic exposures. During that time stellar magnitudes were almost exclusively determined by measuring the size of in-focus stellar

  16. Is increasing industrialization affecting remote ecosystem health in the South Americas? Insights from ocean surface water measurements of As, Sb and Pb from a GEOTRACES transect

    NASA Astrophysics Data System (ADS)

    Weiss, Dominik; Salaun, Pascal; Van den Berg, Stan; Bi, Zaoshun

    2014-05-01

    Continued industrial development of the South Americas with increasing atmospheric emission of toxic trace metals has lead to a growing concern about possible effects on pristine ecosystem health. Concentration measurements of trace metals in ocean surface waters in the North Atlantic have successfully revealed the global extent of atmospheric pollution in the Northern Hemisphere during economical growth in the USA and Europe, suggesting a similar approach can be applied to the Southern Hemisphere. To this end, we determined concentrations of lead (Pb), antimony (Sb) and arsenic (As) using voltammetry in surface water samples of the South Atlantic Ocean collected during the third leg of the GEOTRACES West Atlantic Cruise. These elements are volatile and therefore most likely suitable tracer elements of industrial emissions from South America. The samples were not filtered and the solutions were acidified and UV digested. Total concentrations of Pb were detected. Detected As levels correspond to the sum of inorganic species (AsIII + AsV) plus the mono methyl arsenic acid (MMA) while the dimethyl arsenic acid (DMA) is not detected in such conditions. For Sb, detected levels correspond at least to the sum of inorganic fractions (SbIII + SbV). The measured concentrations for Pb varied from 6 to 23 pM. Concentrations were highest at -35° latitude and lowest at -40° and -50° latitude. We found a decreasing trend from about -35° latitude southwards. The average concentrations of As was 20 nM and of Sb 1.2 nM. Arsenic showed a more significant north to south trend than Sb. Arsenic concentration was highest at -23 ° latitude (21 nM) and the lowest at -43 ° latitude (17.7 nM). Antimony concentration was highest at -31 ° latitude (1.5 nM) and lowest at -35 ° latitude (1.0 nM). Our preliminary data suggests that the major industrial centres in Brazil (i.e., Sao Paolo, Rio de Janeiro) and Argentina (i.e., Buenos Aires) affect atmospheric metal fluxes to remote environments. The concentrations, however, are not as high as determined in the Northern Hemisphere, suggesting a less drastic impact. That is also reflected in air quality data from the major cities.

  17. Surface Facial Electromyography, Skin Conductance, and Self-Reported Emotional Responses to Light- and Season-Relevant Stimuli in Seasonal Affective Disorder

    PubMed Central

    Lindsey, Kathryn Tierney; Rohan, Kelly J.; Roecklein, Kathryn A.; Mahon, Jennifer N.

    2011-01-01

    Background Learned associations between depressive behavior and environmental stimuli signaling low light availability and winter season may play a role in seasonal affective disorder (SAD). The purpose of this study was to determine whether light and season environmental cues elicit emotional responses that are distinct in individuals with SAD. Methods Twenty-four currently depressed SAD participants were compared to 24 demographically-matched controls with no depression history on emotional responses to outdoor scenes captured under two light intensity (i.e., clear, sunny vs. overcast sky) and three season (i.e., summer with green leaves, fall with autumn foliage, and winter with bare trees) conditions. Emotion measures included surface facial electromyography (EMG) activity in the corrugator supercilii and zygomaticus major muscle regions, skin conductance, and self-reported mood state on the Profile of Mood States Depression–Dejection Subscale. Results Light intensity was a more salient cue than season in determining emotional reactions among SAD participants. Relative to controls, SAD participants displayed more corrugator activity, more frequent significant skin conductance responses (SCR), greater SCR magnitude, and more self-reported depressed mood in response to overcast stimuli and less corrugator activity, lower SCR magnitude, and less self-reported depressed mood in response to sunny stimuli. Limitations Study limitations include the single, as opposed to repeated, assessment and the lack of a nonseasonal depression group. Conclusions These findings suggest that extreme emotional reactivity to light-relevant stimuli may be a correlate of winter depression; and future work should examine its potential onset or maintenance significance. PMID:21600661

  18. How surface fire in Siberian Scots pine forests affects soil organic carbon in the forest floor: Stocks, molecular structure, and conversion to black carbon (charcoal)

    NASA Astrophysics Data System (ADS)

    Czimczik, Claudia I.; Preston, Caroline M.; Schmidt, Michael W. I.; Schulze, Ernst-Detlef

    2003-03-01

    In boreal forests, fire is a frequent disturbance and converts soil organic carbon (OC) to more degradation-resistant aromatic carbon, i.e., black carbon (BC) which might act as a long-term atmospheric-carbon sink. Little is known on the effects of fires on boreal soil OC stocks and molecular composition. We studied how a surface fire affected the composition of the forest floor of Siberian Scots pine forests by comparing the bulk elemental composition, molecular structure (13C-MAS NMR), and the aromatic carbon fraction (BC and potentially interfering constituents like tannins) of unburned and burned forest floor. Fire reduced the mass of the forest floor by 60%, stocks of inorganic elements (Si, Al, Fe, K, Ca, Na, Mg, Mn) by 30-50%, and of OC, nitrogen, and sulfur by 40-50%. In contrast to typical findings from temperate forests, unburned OC consisted mainly of (di-)O-alkyl (polysaccharides) and few aromatic structures, probably due to dominant input of lichen biomass. Fire converted OC into alkyl and aromatic structures, the latter consisting of heterocyclic macromolecules and small clusters of condensed carbon. The small cluster size explained the small BC concentrations determined using a degradative molecular marker method. Fire increased BC stocks (16 g kg-1 OC) by 40% which translates into a net-conversion rate of 0.7% (0.35% of net primary production) unburned OC to BC. Here, however, BC was not a major fraction of soil OC pool in unburned or burned forest floor, either due to rapid in situ degradation or relocation.

  19. A Naturally Occurring Single-Residue Mutation in the Translocator Domain of Neisseria meningitidis NhhA Affects Trimerization, Surface Localization, and Adhesive Capabilities?†

    PubMed Central

    Echenique-Rivera, Hebert; Brunelli, Brunella; Scarselli, Maria; Taddei, Anna Rita; Pizza, Mariagrazia; Aricò, Beatrice; Serruto, Davide

    2011-01-01

    Neisseria meningitidis NhhA (Neisseria hia/hsf homologue A) is an oligomeric outer membrane protein belonging to the family of trimeric autotransporter adhesins. NhhA mediates the interaction of N. meningitidis with human epithelial cells and components of the extracellular matrix. The recombinant protein is able to induce bactericidal antibodies and hence has also been considered a potential vaccine candidate. In this study, we analyzed the production of NhhA in a large panel of N. meningitidis strains belonging to different serogroups and clonal complexes. We found that trimeric NhhA was produced at different levels by the various strains tested. In some strains belonging to the clonal complex ST41/44, the protein is detectable only as a monomer. Sequencing of the nhhA gene and generation of complementing strains in different genetic backgrounds have proved that a single mutation (Gly to Asp) in the translocator domain affected both trimerization and surface localization of NhhA. In vitro infection assays showed that this mutation impairs meningococcal NhhA-mediated adhesion, suggesting that strains carrying the mutation may rely on different strategies or molecules to mediate interaction with host cells. Finally, we demonstrated that N. meningitidis ST41/44 strains producing the mutated form did not induce killing mediated by NhhA-specific bactericidal antibodies. Our data help to elucidate the secretion mechanisms of trimeric autotransporters and to understand the contribution of NhhA in the evolutionary process of host-Neisseria interactions. Also, they might have important implications for the evaluation of NhhA as a vaccine candidate. PMID:21844231

  20. The Amazon rainforest, climate change, and drought: How will what is below the surface affect the climate of tropical South America?

    NASA Astrophysics Data System (ADS)

    Harper, A.; Denning, A. S.; Baker, I.; Randall, D.; Dazlich, D.

    2008-12-01

    Several climate models have predicted an increase in long-term droughts in tropical South America due to increased greenhouse gases in the atmosphere. Although the Amazon rainforest is resilient to seasonal drought, multi-year droughts pose a definite problem for the ecosystem's health. Furthermore, drought- stressed vegetation participates in feedbacks with the atmosphere that can exacerbate drought. Namely, reduced evapotranspiration further dries out the atmosphere and affects the regional climate. Trees in the rainforest survive seasonal drought by using deep roots to access adequate stores of soil moisture. We investigate the climatic impacts of deep roots and soil moisture by coupling the Simple Biosphere (SiB3) model to Colorado State University's general circulation model (BUGS5). We compare two versions of SiB3 in the GCM during years with anomalously low rainfall. The first has strong vegetative stress due to soil moisture limitations. The second experiences less stress and has more realistic representations of surface biophysics. In the model, basin-wide reductions in soil moisture stress result in increased evapotranspiration, precipitation, and moisture recycling in the Amazon basin. In the savannah region of southeastern Brazil, the unstressed version of SiB3 produces decreased precipitation and weaker moisture flux, which is more in-line with observations. The improved simulation of precipitation and evaporation also produces a more realistic Bolivian high and Nordeste low. These changes highlight the importance of subsurface biophysics for the Amazonian climate. The presence of deep roots and soil moisture will become even more important if climate change brings more frequent droughts to this region in the future.

  1. Galileo Photometry of Asteroid 243 Ida

    Microsoft Academic Search

    P. Helfenstein; J. Veverka; P. C. Thomas; D. P. Simonelli; K. Klaasen; T. V. Johnson; F. Fanale; J. Granahan; A. S. McEwen; M. Belton; C. Chapman

    1996-01-01

    Galileo imaging observations over phase angles 19.5° to 109.8° are combined with near-opposition Earth-based data to derive the photometric properties of Ida. To first order these properties are uniform over the surface and well modeled at ? = 0.55 ?m by Hapke parameters ?0= 0.22,h= 0.020,B0= 1.5,g= ?0.33, and ? = 18° with corresponding geometric albedop= 0.21±0.030.01and Bond albedoAB= 0.081±0.0170.008.

  2. CCD photometry of the Uranian satellites

    NASA Technical Reports Server (NTRS)

    Buratti, Bonnie J.; Gibson, James; Mosher, Joel A.

    1992-01-01

    Broadband V and R CCD observations of the Uranian satellite system have been obtained over the full range of solar phase angles observable from earth. These first visual observations of the phase curves of Miranda, Ariel, and Umbriel show that Ariel and Miranda exhibit the large opposition surges previously seen on the two outer Uranian Satellites. Umbriel, however, lacks an appreciable opposition surge; its surface is either extremely compact or consists of small particles which lack a backscattered component. The tenuous structure of the other satellites is most likely due to the effects of eons of meteoritic gardening.

  3. The TERMS Project: Improved Orbital Parameters and Photometry of HD168443 and the Photometry Pipeline

    NASA Astrophysics Data System (ADS)

    Pilyavsky, Genady; Mahadevan, S.; Kane, S. R.; Howard, A. W.; Ciardi, D. R.; de Pree, C.; Dragomir, D.; Fischer, D.; Henry, G. W.; Jensen, E. L. N.; Laughlin, G.; Marlowe, H.; Rabus, M.; von Braun, K.; Wright, J. T.; Wang, X.

    2012-01-01

    The discovery of transiting planets around bright stars holds the potential to greatly enhance our understanding of planetary atmospheres. The Transit Ephemeris Refinement and Monitoring Survey (TERMS) project focuses on updating the ephemerides of known exoplanets, put tighter constraints on the orbital parameters and shrink the large errors on the predicted transit windows, enabling photometric monitoring to search for a transit signature. Here, we present the revised orbital parameters and the photometric coverage during a predicted transit window of HD168443b, a massive planet orbiting the bright star HD 168443 (V = 6.92) with a period of 58.11 days. The high eccentricity of the planetary orbit (e = 0.53) significantly enhances the a-priori transit probability (3.7%) from what is expected for a circular orbit (2.5%). The transit ephemeris was updated using refined orbital parameters from additional Keck-HIRES radial velocities. The photometry obtained at the 1 m telescope in Cerro Tololo Inter-American Observatory (CTIO) and the T8 0.8 m Automated Photometric Telescope (APT) at Fairborn Observatory achieved the necessary millimag precision. The expected change in flux (0.5%) for HD168443 was not observed during the predicted transit window, thus allowing us to rule out the transit and put tighter constrains on the orbital inclination of HD168443b. Additionally, we present the software used to analyze the CTIO data. Developed by the TERMS team, this IDL based package is a fast, precise, and easy to use program which has eliminated the need for external software and command line prompts by utilizing the functionality of a graphical user interface (GUI).

  4. The impact of main belt asteroids on infrared--submillimetre photometry and source counts

    E-print Network

    Cs. Kiss; A. Pal; Th. G. Mueller; P. Abraham

    2007-11-28

    > Among the components of the infrared and submillimetre sky background, the closest layer is the thermal emission of dust particles and minor bodies in the Solar System. This contribution is especially important for current and future infrared and submillimetre space instruments --like those of Spitzer, Akari and Herschel -- and must be characterised by a reliable statistical model. > We describe the impact of the thermal emission of main belt asteroids on the 5...1000um photometry and source counts, for the current and future spaceborne and ground-based instruments, in general, as well as for specific dates and sky positions. > We used the statistical asteroid model (SAM) to calculate the positions of main belt asteroids down to a size of 1km, and calculated their infrared and submillimetre brightness using the standard thermal model. Fluctuation powers, confusion noise values and number counts were derived from the fluxes of individual asteroids. > We have constructed a large database of infrared and submillimetre fluxes for SAM asteroids with a temporal resolution of 5 days, covering the time span January 1, 2000 -- December 31, 2012. Asteroid fluctuation powers and number counts derived from this database can be obtained for a specific observation setup via our public web-interface. > Current space instruments working in the mid-infrared regime (Akari and Spitzer Space Telescopes) are affected by asteroid confusion noise in some specific areas of the sky, while the photometry of space infrared and submillimetre instruments in the near future (e.g. Herschel and Planck Space Observatories) will not be affected by asteroids. Faint main belt asteroids might also be responsible for most of the zodiacal emission fluctuations near the ecliptic.

  5. The Spitzer Local Volume Legacy (LVL) global optical photometry

    NASA Astrophysics Data System (ADS)

    Cook, David O.; Dale, Daniel A.; Johnson, Benjamin D.; Van Zee, Liese; Lee, Janice C.; Kennicutt, Robert C.; Calzetti, Daniela; Staudaher, Shawn M.; Engelbracht, Charles W.

    2014-11-01

    We present the global optical photometry of 246 galaxies in the Local Volume Legacy (LVL) survey. The full volume-limited sample consists of 258 nearby (D < 11 Mpc) galaxies whose absolute B-band magnitude span a range of -9.6 < MB < -20.7 mag. A composite optical (UBVR) data set is constructed from observed UBVR and Sloan Digital Sky Survey ugriz imaging, where the ugriz magnitudes are transformed into UBVR. We present photometry within three galaxy apertures defined at UV, optical, and IR wavelengths. Flux comparisons between these apertures reveal that the traditional optical R25 galaxy apertures do not fully encompass extended sources. Using the larger IR apertures, we find colour-colour relationships where later type spiral and irregular galaxies tend to be bluer than earlier type galaxies. These data provide the missing optical emission from which future LVL studies can construct the full panchromatic (UV-optical-IR) spectral energy distributions.

  6. High-speed multicolour photometry with CMOS cameras

    NASA Astrophysics Data System (ADS)

    Pokhvala, S. M.; Zhilyaev, B. E.; Reshetnyk, V. M.

    2012-11-01

    We present the results of testing the commercial digital camera Nikon D90 with a CMOS sensor for high-speed photometry with a small telescope Celestron 11'' at the Peak Terskol Observatory. CMOS sensor allows to perform photometry in 3 filters simultaneously that gives a great advantage compared with monochrome CCD detectors. The Bayer BGR colour system of CMOS sensors is close to the Johnson BVR system. The results of testing show that one can carry out photometric measurements with CMOS cameras for stars with the V-magnitude up to ?14^{m} with the precision of 0.01^{m}. Stars with the V-magnitude up to ˜10 can be shot at 24 frames per second in the video mode.

  7. Accuracy of Star Cluster Parameters from Integrated UBVRI Photometry

    E-print Network

    D. Narbutis; A. Bridzius; R. Stonkute; V. Vansevicius

    2007-12-23

    We study the capability of the UBVRI photometric system to quantify star clusters in terms of age, metallicity, and color excess by their integrated photometry. The well known age-metallicity-extinction degeneracy was analyzed for various parameter combinations, assuming different levels of photometric accuracy. We conclude that the UBVRI photometric system enables us to estimate star cluster parameters over a wide range, if the overall photometric accuracy is better than ~0.03 mag.

  8. Blue-light imagery and photometry of sprites

    Microsoft Academic Search

    David M. Suszcynsky; Robert Roussel-Dupré; Walter A. Lyons; Russell A. Armstrong

    1998-01-01

    We have obtained blue (350–475 nm) video images and simultaneous high-time resolution narrow-band blue (415–435 nm) photometry records of four sprite events. The brightest blue images show a sustained tendril geometry and a nearly constant intensity of emission over the entire vertical extent of the sprite (from 35–90 km altitude). Photometer light curves display an exponential decay with a 0.3

  9. CCD Photometry of SW Ursae Majoris during the 1996 Superoutburst

    E-print Network

    I. Semeniuk; A. Olech; T. Kwast; M. Nalezyty

    1997-04-22

    We present CCD R photometry of SW Ursae Majoris - an SUUMa type cataclysmic variable - obtained during its April 1996 superoutburst. The mean value of the superhump period derived from our observations is 0.05818(+/-2) days (83.8 min). The analysis of times of superhump maxima gives clear evidence for the increase of the superhump period with dPsh/dt=0.000089.

  10. ISOCAM Photometry of Narrow-Line X-ray Galaxies

    E-print Network

    J. D. Law-Green; A. Zezas; M. J. Ward; C. Boisson

    1998-12-23

    Mid-infrared photometry of the hosts of Narrow-Line X-ray Galaxies at 6 microns and 12 microns has been attempted with ISOCAM. No conclusive detections have been made. This implies that these are quiescent objects with little or no active star-formation. Neither X-ray binaries nor starburst-driven superwinds are consistent explanations for the X-ray emission in these objects. We conclude that these NLXGs are predominantly AGN-powered.

  11. PythonPhot: Simple DAOPHOT-type photometry in Python

    NASA Astrophysics Data System (ADS)

    Jones, David O.; Scolnic, Daniel M.; Rodney, Steven A.

    2015-01-01

    PythonPhot is a simple Python translation of DAOPHOT-type (ascl:1104.011) photometry procedures from the IDL AstroLib (Landsman 1993), including aperture and PSF-fitting algorithms, with a few modest additions to increase functionality and ease of use. These codes allow fast, easy, and reliable photometric measurements and are currently used in the Pan-STARRS supernova pipeline and the HST CLASH/CANDELS supernova analysis.

  12. UBVI photometry of the intermediate age open cluster NGC 6939

    E-print Network

    Gloria Andreuzzi; Angela Bragaglia; Monica Tosi; Gianni Marconi

    2003-11-13

    We present CCD UBVI photometry of the nearby, intermediate age open cluster NGC 6939. Using the synthetic Colour - Magnitude Diagrams technique we estimate the following parameters: age between 1.3 and 1.0 Gyr (depending on whether or not overshooting is considered), reddening 0.34

  13. Determining thallium in semiconductor crystals by solvent extraction and photometry

    Microsoft Academic Search

    I. S. Balog; P. P. Kish; Ya. R. Bazel; E. Yu. Peresh

    1987-01-01

    Promising optoelectronic materials are represented by single crystals of compounds in the systems TlX-Ge (Sn, Pb, Cd)Xâ, where X is Cl, Br, or I. To choose growth conditions for good crystals, one needs information on the uniformity of the thallium distributions. Solvent extraction followed by photometry is widely used, which is based on extracting ionic associated groups (IA) such as

  14. Astrometry and Photometry for Cool Dwarfs and Brown Dwarfs

    Microsoft Academic Search

    Conard C. Dahn; Hugh C. Harris; Frederick J. Vrba; Harry H. Guetter; Blaise Canzian; Arne A. Henden; Stephen E. Levine; Christian B. Luginbuhl; Alice K. B. Monet; David G. Monet; Jeffrey R. Pier; Ronald C. Stone; Richard L. Walker; Adam J. Burgasser; John E. Gizis; J. Davy Kirkpatrick; James Liebert; I. Neill Reid

    2002-01-01

    Trigonometric parallax determinations are presented for 28 late-type dwarfs and brown dwarfs, including eight M dwarfs with spectral types between M7 and M9.5, 17 L dwarfs with spectral types between L0 and L8, and three T dwarfs. Broadband photometry at CCD wavelengths (VRIz*) and\\/or near-IR wavelengths (JHK) is presented for these objects and for 24 additional late-type dwarfs. Supplemented with

  15. Multicolor Photometry of the Uranus Irregular Satellites Sycorax and Caliban

    E-print Network

    Michele Maris; Giovanni Carraro; Gabriele Cremonese; Marco Fulle

    2001-01-27

    We report on accurate BVRI photometry for the two Uranus irregular satellites Sycorax and Caliban. We derive colours, showing that Sycorax is bluer than Caliban. Our data allows us to detect a significant variability in the Caliban's light-curve, which suggests an estimated period of about 3 hours. Despite it is the brighter of the two bodies, Sycorax does not display a strong statistically significant variability. However our data seem to suggest a period of about 4 hours

  16. PHOTOMETRY OF ULTRACOOL DWARFS D. A. Golimowski,1

    E-print Network

    Golimowski, David A.

    , the numbers of ultracool dwarfs (Teff P 2400 K) for which L0 and M0 measurements have been reported. We compute Lbol, BCK, and Teff for 42 dwarfs whose flux-calibrated JHK spectra, L0 photometry. Teff declines steeply and monotonically for types M6­L7 and T4­T9, but it is nearly constant at $1450 K

  17. Aperture Photometry of Saturated Star Images from Digitised Photographic Plates

    E-print Network

    J. L. Innis; D. W. Coates; A. P. Borisova; M. K. Tsvetkov

    2005-02-21

    Saturated stellar images on digitised photographic plates are many times greater in area than the `seeing disk' seen in unsaturated CCD images. Indeed the flux profile of a bright star can be traced out for several degrees from the star's centre. The radius of the saturated stellar image can often be directly related to the magnitude of the star, a fact well known and exploited in iris photometry. In this work we compare the radial flux profile of stars in the approximate range B ~9 to ~13 mag, obtained from scans of plates from the Bamberg Sky Patrol archive, with a profile of the form measured by King. We show that simple aperture photometry of saturated stellar images, obtained from photo-positives of scanned photographic plates, yield data that are in agreement with simulations using a (saturated) synthetic stellar radius profile. Raw plate magnitudes from this aperture photometry can be easily and satisfactorily transformed to standard magnitudes, as demonstrated in a recent study carried out by the current authors.

  18. Ultra-High Precision, Ultra-Wide-Field Optical Photometry

    NASA Astrophysics Data System (ADS)

    Strassmeier, K. G.

    The low scintillation noise and the long continuous darkness are among the unique properties of the Dome-C site on the east Antarctic plateau. Ultra-high precision optical photometry is therefore among the techniques best suited for this particular site. We propose a telescope (ICE-T) optimized for ultra-high and ultra wide field photometry for Dome C. It consists of two 60cm optical ultra-wide-field Wynne-Schmidt telescopes and one 18cm narrow-field Maksutov spectrophotometric telescope on a single mount. ICE-T is currently a team effort of the German Alfred-Wegener-Institute for Polar Research, the Italian Universities of Padova and Perugia, the INAF Observatory Catania, and the Catalonian IEEC in Barcelona, Spain, and the AIP, with collaboration from the University of New South Wales, Australia and the University of St. Andrews, UK. In this paper, I discuss some of the many problems associated with sub-milli-mag photometry.

  19. Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems

    E-print Network

    Katrin Jordi; Eva K. Grebel; Karin Ammon

    2006-09-05

    We present empirical color transformations between the Sloan Digital Sky Survey (SDSS) ugriz photometry and Johnson-Cousins UBVRI system and Becker's RGU system, respectively. Owing to the magnitude of data that is becoming available in the SDSS photometric system it is particularly important to be able to convert between this new system and traditional photometric systems. Unlike earlier published transformations we based our calculations on stars actually measured by the SDSS with the SDSS 2.5-m telescope. The photometric database of the SDSS provides in a sense a single-epoch set of 'tertiary standards' covering more than one quarter of the sky. Our transformations should facilitate their use to easily and reliably derive the corresponding approximate Johnson-Cousins or RGU magnitudes. The SDSS survey covers a number of areas that were previously established as standard fields in the Johnson-Cousins system, in particular, fields established by Landolt and by Stetson. We used these overlapping fields to create well-photometered star samples on which our calculated transformations are based. For the RGU photometry we used fields observed in the framework of the new Basel high-latitude field star survey. We calculated empirical color transformations between SDSS photometry and Johnson-Cousins UBVRI and Becker's RGU system. For all transformations we found linear relations to be sufficient. Furthermore we showed that the transformations between the Johnson-Cousins and the SDSS system have a slight dependence on metallicity.

  20. M2K Planet Search: Spectroscopic Screening and Transit Photometry

    NASA Astrophysics Data System (ADS)

    Mann, Andrew; Gaidos, E.; Fischer, D.; Lepine, S.

    2010-10-01

    The M2K project is a search for planets orbiting nearby early M and late K dwarf drawn from the SUPERBLINK catalog. M and K dwarfs are highly attractive targets for finding low-mass and habitable planets because (1) close-in planets are more likely to orbit within their habitable zone, (2) planets orbiting them induce a larger Doppler signal and have deeper transits than similar planets around F, G, and early K type stars, (3) planet formation models predict they hold an abundance of super-Earth sized planets, and (4) they represent the vast majority of the stars close enough for direct imaging techniques. In spite of this, only 10% of late K and early M dwarfs are being monitored by current Doppler surveys. As part of the M2K project we have obtained low-resolution spectra for more than 2000 of our sample of 10,000 M and K dwarfs. We vet our sample by screening these stars for high metallicity and low chromospheric activity. We search for transits on targets showing high RMS Doppler signal and photometry candidates provided by SuperWASP project. By using "snapshot” photometry have been able to achieve sub-millimag photometry on numerous transit targets in the same night. With further follow-up observations we will be able to detect planets smaller than 10 Earth masses.

  1. Pushing the precision limit of ground-based eclipse photometry

    E-print Network

    M. Gillon; D. R. Anderson; B. -O. Demory; D. M. Wilson; C. Hellier; D. Queloz; C. Waelkens

    2008-06-30

    Until recently, it was considered by many that ground-based photometry could not reach the high cadence sub-mmag regime because of the presence of the atmosphere. Indeed, high frequency atmospheric noises (mainly scintillation) limit the precision that high SNR photometry can reach within small time bins. If one is ready to damage the sampling of his photometric time-series, binning the data (or using longer exposures) allows to get better errors, but the obtained precision will be finally limited by low frequency noises. To observe several times the same planetary eclipse and to fold the photometry with the orbital period is thus generally considered as the only option to get very well sampled and precise eclipse light curve from the ground. Nevertheless, we show here that reaching the sub-mmag sub-min regime for one eclipse is possible with a ground-based instrument. This has important implications for transiting planets characterization, secondary eclipses measurement and small planets detection from the ground.

  2. Identifying Contaminated K-Band Globular Cluster RR Lyrae Photometry

    NASA Astrophysics Data System (ADS)

    Majaess, D.; Turner, D.; Gieren, W.

    2012-10-01

    Acquiring near-infrared K-band (2.2 ?m) photometry for RR Lyrae variables in globular clusters and nearby galaxies is advantageous, since the resulting distances are less impacted by reddening and metallicity. However, K-band photometry for RR Lyrae variables in M5, Reticulum, M92, ? Cen, and M15 display clustercentric trends. The Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) data imply that multiple stars in close proximity to RR Lyrae variables located near the cluster core, where the stellar density increases markedly, are generally unresolved in ground-based images. RR Lyrae variables near the cluster core appear to suffer from photometric contamination, thereby yielding underestimated cluster distances and biased ages. The impact is particularly pernicious, since the contamination propagates a systematic uncertainty into the distance scale, and hinders the quest for precision cosmology. The clustercentric trends are probably unassociated with variations in chemical composition, since an empirical K-band period-magnitude relation inferred from Araucaria/VLT (Very Large Telescope) data for RR Lyrae variables in the Sculptor dSph exhibits a negligible metallicity dependence: (0.059 ± 0.095) × [Fe/H]ZW, a finding that supports prior observational results. A future multiepoch, high-resolution near-infrared survey, analogous to the optical HST ACS Galactic Globular Cluster Survey, may be employed to establish K-band photometry for the contaminating stars discussed here.

  3. MATPHOT algorithm for digital point spread function CCD stellar photometry

    NASA Astrophysics Data System (ADS)

    Mighell, Kenneth J.

    2002-12-01

    The MATPHOT algorithm for digital Point Spread Function (PSF) CCD stellar photometry is described. A theoretical photometric and astrometric performance model is presented for PSF-fitting stellar photometry. MATPHOT uses a digital representation of the sampled PSF consisting of a numerical table (e.g., a matrix or a FITS image) instead of an analytical function. MATPHOT achieves accurate stellar photometry with under-sampled CCD observations with super-sampled PSFs. MATPHOT currently locates a PSF within the observational model using a 21-pixel-wide damped sinc interpolation function. Position partial derivatives of the observational model are determined using numerical differentiation techniques. Results of MATPHOT-based design studies of the optical performance of the Next Generation Space Telescope are presented; observations of bright stars analyzed with the MATPHOT algorithm can yield millimag photometric errors with millipixel relative astrometric errors -- or better -- if observed with a perfect detector. Plans for the future development of a parallel-processing version of the MATPHOT algorithm using Beowulf clusters are described. All of the C source code and documentation for MATPHOT is freely available as part of the MXTOOLS package for IRAF (http://www.noao.edu/staff/mighell/mxtools). This work is supported by a grant from NASA's Office of Space Science.

  4. High speed low noise multiplexed three color absorbance photometry.

    PubMed

    Dadesh, Khaled M; Kurup, G K; Basu, Amar S

    2011-01-01

    Multispectral photometry is often required to distinguish samples in flow injection analysis and flow cytometry; however, the cost of multiple light detectors, filters, and optical paths contribute to the high cost of multicolor and spectral detection systems. This paper describes frequency division multiplexing (FDM), a simple approach for performing multi-wavelength absorbance photometry with a single light detector and a single interrogation window. In previous efforts, modulation frequencies were <10 KHz, resulting in a detector bandwidth of <20 Hz. This paper presents a high frequency FDM circuit which can increase the oscillation frequencies to several 100 KHz, improving the detection bandwidth by a factor of 10 while still maintaining low cost. Light from 3 different LED sources are encoded into unique frequency channels, passed through the detection cell, and later demodulated using phase-sensitive electronics. Electronic multiplexing couples all light sources into a single optical train without spectral filters. Theory and high frequency considerations are demonstrated. Simultaneous three color absorbance detection is demonstrated in solutions and in flowing droplet microreactors. This technique can potentially reduce the cost of multicolor photometry by replacing expensive optical components with low-cost electronics. PMID:22254245

  5. Galileo photometry of Apollo landing sites

    NASA Astrophysics Data System (ADS)

    Helfenstein, P.; Veverka, J.; Head, James W.; Pieters, C.; Pratt, S.; Mustard, J.; Klaasen, K.; Neukum, G.; Hoffmann, H.; Jaumann, R.

    1993-03-01

    As of December 1992, the Galileo spacecraft performed its second and final flyby (EM2), of the Earth-Moon system, during which it acquired Solid State Imaging (SSI) camera images of the lunar surface suitable for photometric analysis using Hapke's, photometric model. These images, together with those from the first flyby (EM1) in December 1989, provide observations of all of the Apollo landing sites over a wide range of photometric geometries and at eight broadband filter wavelengths ranging from 0.41 micron to 0.99 micron. We have completed a preliminary photometric analysis of Apollo landing sites visible in EM1 images and developed a new strategy for a more complete analysis of the combined EM1 and EM2 data sets in conjunction with telescopic observations and spectrogoniometric measurements of returned lunar samples. No existing single data set, whether from spacecraft flyby, telescopic observation, or laboratory analysis of returned samples, describes completely the light scattering behavior of a particular location on the Moon at all angles of incidence (i), emission (e), and phase angles (a). Earthbased telescopic observations of particular lunar sites provide good coverage of incidence nad phase angles, but their range in emission angle is limited to only a few degrees because of the Moon's synchronous rotation. Spacecraft flyby observations from Galileo are now available for specific lunar features at many photometric geometries unobtainable from Earth; however, this data set lacks coverage at very small phase angles (a less than 13 deg) important for distinguishing the well-known 'opposition effect'. Spectrogoniometric measurements from returned lunar samples can provide photometric coverage at almost any geometry; however, mechanical properties of prepared particulate laboratory samples, such as particle compaction and macroscopic roughness, likely differ from those on the lunar surface. In this study, we have developed methods for the simultaneous analysis of all three types of data: we combine Galileo and telescopic observations to obtain the most complete coverage with photometric geometry, and use spectrogoniometric observations of lunar soils to help distinguish the photometric effects of macroscopic roughness from those caused by particle phase function behavior (i.e., the directional scattering properties of regolith particles).

  6. Galileo photometry of Apollo landing sites

    NASA Technical Reports Server (NTRS)

    Helfenstein, P.; Veverka, J.; Head, James W.; Pieters, C.; Pratt, S.; Mustard, J.; Klaasen, K.; Neukum, G.; Hoffmann, H.; Jaumann, R.

    1993-01-01

    As of December 1992, the Galileo spacecraft performed its second and final flyby (EM2), of the Earth-Moon system, during which it acquired Solid State Imaging (SSI) camera images of the lunar surface suitable for photometric analysis using Hapke's, photometric model. These images, together with those from the first flyby (EM1) in December 1989, provide observations of all of the Apollo landing sites over a wide range of photometric geometries and at eight broadband filter wavelengths ranging from 0.41 micron to 0.99 micron. We have completed a preliminary photometric analysis of Apollo landing sites visible in EM1 images and developed a new strategy for a more complete analysis of the combined EM1 and EM2 data sets in conjunction with telescopic observations and spectrogoniometric measurements of returned lunar samples. No existing single data set, whether from spacecraft flyby, telescopic observation, or laboratory analysis of returned samples, describes completely the light scattering behavior of a particular location on the Moon at all angles of incidence (i), emission (e), and phase angles (a). Earthbased telescopic observations of particular lunar sites provide good coverage of incidence nad phase angles, but their range in emission angle is limited to only a few degrees because of the Moon's synchronous rotation. Spacecraft flyby observations from Galileo are now available for specific lunar features at many photometric geometries unobtainable from Earth; however, this data set lacks coverage at very small phase angles (a less than 13 deg) important for distinguishing the well-known 'opposition effect'. Spectrogoniometric measurements from returned lunar samples can provide photometric coverage at almost any geometry; however, mechanical properties of prepared particulate laboratory samples, such as particle compaction and macroscopic roughness, likely differ from those on the lunar surface. In this study, we have developed methods for the simultaneous analysis of all three types of data: we combine Galileo and telescopic observations to obtain the most complete coverage with photometric geometry, and use spectrogoniometric observations of lunar soils to help distinguish the photometric effects of macroscopic roughness from those caused by particle phase function behavior (i.e., the directional scattering properties of regolith particles).

  7. Synthetic Spectroscopy and Photometry for the Sun

    NASA Astrophysics Data System (ADS)

    Bell, R. A.

    1993-05-01

    The availability of a digital version of the solar line spectrum (Kitt Peak Preliminary Solar Atlas, Brault & Testerman 1972) has made it possible to carry out detailed comparisons of observed and synthetic spectra. The more accurately the spectrum of the Sun, and other standard stars, can be reproduced, the more likely the line list is to give reliable results in other applications. Detailed comparisons have been made using three lists. The first two are: 1) One which has been used repeatedly by the author and collaborators e.g. Bell, Dickens & Gustafsson (ApJ,229,604,1979); Tripicco & Bell (AJ,103,1285,1992); 2) One derived from Kurucz (Stellar Atmospheres: Beyond Classical Models, Kluwer, Dordrecht, p408,1991) for elements between Ca and Ni, supplemented with lines for other elements from Kurucz & Peytremann (SAO Spec Rept 362,1975) and molecular lines from the author's list (e.g. Bell & Gustafsson MNRAS,236,653,1989). The Kurucz list predicts many lines in the solar spectrum which are either not seen or are observed to be far weaker. The errors in oscillator strength may exceed a factor of 10. On the other hand, there are not a corresponding number of lines which are observed but which are not present in the synthetic spectra. Needless to say, this excess in the computed line absorption will affect the calculation of both model atmospheres and synthetic magnitudes. For example, the computed U-B colors will be too red. In view of these errors, and the much better fit which spectra calculated using the author's lists give to the solar line spectrum, the Kurucz list has been used only to fill in gaps in the author's list, thereby creating a third list. This list also incorporates new laboratory gf values (e.g. O'Brian et al. JOSA B,8,1185,1991). Detailed comparisons of observed and synthetic solar spectra from the different lists are shown.

  8. Galileo photometry of asteroid 243 Ida

    USGS Publications Warehouse

    Helfenstein, P.; Veverka, J.; Thomas, P.C.; Simonelli, D.P.; Klaasen, K.; Johnson, T.V.; Fanale, F.; Granahan, J.; McEwen, A.S.; Belton, M.; Chapman, C.

    1996-01-01

    Galileo imaging observations over phase angles 19.5?? to 109.8?? are combined with near-opposition Earth-based data to derive the photometric properties of Ida. To first order these properties are uniform over the surface and well modeled at ?? = 0.55 ??m by Hapke parameters ????0 = 0.22, h = 0.020, B0 = 1.5, g = -0.33, and ?? = 18?? with corresponding geometric albedo p = 0.21??0.030.01 and Bond albedo AB = 0.081??0.0170.008. Ida's photometric properties are more similar to those of "average S-asteroids" (P. Helfenstein and J. Veverka 1989, Asteroids II, Univ. of Arizona Press, Tucson) than are those of 951 Gaspra. Two primary color units are identified on Ida: Terrain A exhibits a spectrum with relatively shallower 1-??m absorption and a relatively steeper red spectral slope than average Ida, while Terrain B has a deeper 1-??m absorption and a less steep red slope. The average photometric properties of Ida and Terrain A are similar while those of Terrain B differ mostly in having a slightly higher value of ????0 (0.22 versus 0.21), suggesting that Terrain B consists of slightly brighter, more transparent regolith particles. Galileo observations of Ida's satellite Dactyl over phase angles 19.5?? to 47.6?? suggest photometric characteristics similar to those of Ida, the major difference being Dactyl's slightly lower albedo (0.20 compared to 0.21). ?? 1990 Academic Press, Inc.

  9. Diagnostics of Stellar Modelling from Spectroscopy and Photometry of Globular Clusters

    E-print Network

    Angelou, George; Constantino, Thomas; Church, Ross; Stancliffe, Richard; Lattanzio, John

    2015-01-01

    We conduct a series of comparisons between spectroscopic and photometric observations of globular clusters and stellar models to examine their predictive power. Data from medium-to-high resolution spectroscopic surveys of lithium allow us to investigate first dredge-up and extra mixing in two clusters well separated in metallicity. Abundances at first dredge-up are satisfactorily reproduced but there is preliminary evidence to suggest that the models overestimate the luminosity at which the surface composition first changes in the lowest-metallicity system. Our models also begin extra mixing at luminosities that are too high, demonstrating a significant discrepancy with observations at low metallicity. We model the abundance changes during extra mixing as a thermohaline process and determine that the usual diffusive form of this mechanism cannot simultaneously reproduce both the carbon and lithium observations. Hubble Space Telescope photometry provides turnoff and bump magnitudes in a large number of globula...

  10. A 3D extinction map of the Northern Galactic Plane based on IPHAS photometry

    E-print Network

    Sale, S E; Barentsen, G; Farnhill, H J; Raddi, R; Barlow, M J; Eislöffel, J; Vink, J S; Rodríguez-Gil, P; Wright, N J

    2014-01-01

    We present a three dimensional map of extinction in the Northern Galactic Plane derived using photometry from the IPHAS survey. The map has fine angular ($\\sim 10$ arcmin) and distance (100 pc) sampling allied to a significant depth ($\\gtrsim 5$ kpc). We construct the map using a method based on a hierarchical Bayesian model as previously described by Sale (2012). In addition to mean extinction, we also measure differential extinction, which arises from the fractal nature of the ISM, and show that it will be the dominant source of uncertainty in estimates of extinction to some arbitrary position. The method applied also furnishes us with photometric estimates of the distance, extinction, effective temperature, surface gravity, and mass for $\\sim 38$ million stars. Both the extinction map and the catalogue of stellar parameters are made publicly available via http://www.iphas.org/extinction.

  11. VizieR Online Data Catalog: Galaxies morphology and IR photometry II. (Gavazzi+ 1996)

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Pierini, D.; Baffa, C.; Lisi, F.; Hunt, L. K.; Randone, I.; Boselli, A.

    1996-05-01

    We present near-infrared H-band (1.65?m) surface photometry of 297 galaxies (mostly) in the Coma Supercluster obtained with the Arcetri NICMOS3 camera, ARNICA, mounted on the Gornergrat Infrared Telescope. Magnitudes and diameters within the 21.5mag/arcsec2 isophote, concentration indices, and total H magnitudes are derived. Combining these observations with those obtained similarly using the Calar Alto telescopes (Paper I, ) we find a strong positive correlation between the near-infrared concentration index and the galaxy H-band luminosity, and we analyze the consequent dependence of near-infrared growth-curves on H-band luminosity. For a description of the H band photometric system, see e.g. (2 data files).

  12. Starspots and active regions on IN Com: UBVRI photometry and linear polarization

    NASA Astrophysics Data System (ADS)

    Alekseev, I. Yu.; Kozlova, O. V.

    2014-06-01

    The activity of the variable star IN Com is considered using the latest multicolor UBVRI photometry and linear polarimetric observations carried out during a decade. The photometric variability of the star is fully described using the zonal spottedness model developed at the Crimean Astrophysical Observatory (CrAO). Spotted regions cover up to 22% of the total stellar surface, with the difference in temperatures between the quiet photosphere and the spot umbra being 600 K. The spots are located at middle and low latitudes (40°-55°). The intrinsic broad-band linear polarization of IN Com and its rotational modulation in the U band due to local magnetic fields at the most spotted (active) stellar longitudes were detected for the first time.

  13. STAR FORMATION IN THE OUTER DISKS OF SPIRAL GALAXIES: ULTRAVIOLET AND H{alpha} PHOTOMETRY

    SciTech Connect

    Barnes, Kate L.; Van Zee, Liese [Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States); Skillman, Evan D., E-mail: barneskl@astro.indiana.edu, E-mail: vanzee@astro.indiana.edu, E-mail: skillman@astro.umn.edu [Department of Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

    2011-12-20

    We present an analysis of ultradeep UV and H{alpha} imaging of five nearby spiral galaxies to study the recent star formation in the outer disk. Using azimuthally averaged ellipse photometry as well as aperture photometry of individual young stellar complexes, we measure how star formation rates (SFRs) and UV and H{alpha} colors vary with radius. We detect azimuthally averaged UV flux to {approx}1.2-1.4 R{sub 25} in most galaxies; at the edge of the detected UV disk, the surface brightnesses are 28-29 mag arcsec{sup -2}, corresponding to SFR surface densities of {approx}3 Multiplication-Sign 10{sup -4} M{sub Sun} yr{sup -1} kpc{sup -2}. Additionally, we detect between 120 and 410 young stellar complexes per galaxy, with a significant number of detections out to {approx}1.5 R{sub 25}. We measure radial FUV-NUV profiles, and find that the dispersion in the UV colors of individual young stellar complexes increases with radius. We investigate how radial variations in the frequency of star formation episodes can create color gradients and increasing dispersion in the UV colors of star-forming regions, like those observed in our study. Specifically, we use recently published, high spatial and temporal resolution measurements of {Sigma}{sub SFR} throughout the disk of M33 to estimate the frequency of star formation episodes throughout the disk of a typical spiral galaxy. We use stellar synthesis models of these star formation histories (SFHs) to measure the variations in UV colors and find that we can replicate large dispersions in UV colors based on episodic SFHs.

  14. Karl Schwarzschild's investigations of ``out-of-focus photometry'' between 1897-1899 and his contribution to photographic photometry

    NASA Astrophysics Data System (ADS)

    Habison, Peter

    From 1897 to 1899 Karl Schwarzschild was working at Kuffner Observatory in Vienna. During these years he developed new measuring techniques in the field of photographic photometry, where he particularly studied the quantitative determination of the departure of the reciprocity law during photographic exposures. During that time stellar magnitudes were almost exclusively determined by measuring the size of in-focus stellar disks. Photometry using out-of-focus exposures had been proposed, but had not yet been tried. Schwarzschild's very first paper in this context contains two important results: The intimation that estimating densities on out-of-focus plates could give an accuracy of better than 0.05 mag and the analysis of his photographic data indicated that the reciprocity law (S=I? t), was not obeyed. >From the paper it is not clear how he came to set himself this double task. A series of singly exposed plates date from September 1897, whereas the series of exposures of particular relevance to the question of the time dependence of plate density all date from October 1897. It is remarkable how Schwarzschild succeeded in deriving a better approximation of the characteristic curve's dependence on intensity and time. The talk will focus on Schwarzschild's investigations of ``out-of-focus photometry'' between 1897 and 1899. A few selected original photographic plates will be presented and discussed.

  15. The effects of ultraviolet photometry and binary interactions on photometric redshift and galaxy morphology

    NASA Astrophysics Data System (ADS)

    Zhang, Fenghui; Han, Zhanwen; Li, Lifang; Shan, Hongguang; Zhang, Yu

    2010-10-01

    Using the HYPERZ code and a template spectral library, which consists of four observed galaxy spectra from Coleman, Wu & Weedman (CWW) and eight spectral families built with evolutionary population synthesis models, we present photometric redshift (photo-z) estimates for a spectroscopic sample of 6531 galaxies. Spectroscopic redshifts are also available, and are selected from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) and the Galaxy Evolution Explorer (GALEX) Data Release 4 (DR4). There are also morphologies for a morphological sample of 1502 bright galaxies, which are from the catalogue of Fukugita et al., and these are also matched with SDSS DR7 and GALEX DR4. We find that the inclusion of FUV or NUV, or both, decreases the number of catastrophic identifications (|zphot - zspec | > 1.0). If catastrophic identifications are removed, the inclusion of both FUV and NUV photometry mainly increases the number of non-catastrophic identifications in the low-redshift, and fainter r-magnitude regions. The inclusion of binary interactions mainly increases the number of non-catastrophic identifications and decreases the deviations in the region when only using optical photometry. Based on the morphological galaxy sample, we find that the inclusion of ultraviolet (UV) photometry decreases and increases the probability that early types are classified as burst and E types, respectively. This increases the probability that late types are classified as CWW-Sbc and CWW-Scd types. If catastrophic identifications are excluded, the inclusion of UV data mainly increases the identifications of late types in all redshift, bluer g-r and r >~ 14 regions. Moreover, binary interactions mainly affect the determinations of E and S0 types. In comparison, we find that the reliability and completeness for early- and late-type selection by the HYPERZ code are less than those by the concentration index C = 2.6, the profile likelihood Pexp - PdeV = 0 and colour criteria. Moreover, we find that and discriminators can be used as morphology selection indicators. These two criteria have comparable reliability and completeness for selecting early- and late-type galaxies to C = 2.6 criterion and higher completeness for early-type selection than the criterion.

  16. Extinctions and distances of dark clouds from UGRIJHK photometry of red clump giants: the North America and Pelican nebulae complex

    E-print Network

    Straizys, V

    2009-01-01

    A possibility of applying 2MASS J, H, Ks, IPHAS r, i and MegaCam u, g photometry of red giants for determining distances to dark clouds is investigated. Red clump giants with a small admixture of G5-K1 and M2-M3 stars of the giant branch can be isolated and used in determining distances to separate clouds or spiral arms. The method is applied to an area of the North America and Pelican nebulae complex. Interstellar extinctions of background red giants can be also used for mapping dust surface density in the cloud.

  17. Comparison of ozone determinations by ultraviolet photometry and gas-phase titration

    NASA Technical Reports Server (NTRS)

    Demore, W. B.; Patapoff, M.

    1976-01-01

    A comparison of ozone determinations based on ultraviolet absorption photometry and gas-phase titration (GPT) shows good agreement between the two methods. Together with other results, these findings indicate that three candidate reference methods for ozone, UV photometry, IR photometry, and GPT are in substantial agreement. However, the GPT method is not recommended for routine use by air pollution agencies for calibration of ozone monitors because of susceptibility to experimental error.

  18. Multicolor Photometry of the Merging Galaxy Cluster A2319: Dynamics and Star Formation Properties

    NASA Astrophysics Data System (ADS)

    Yan, Peng-Fei; Yuan, Qi-Rong; Zhang, Li; Zhou, Xu

    2014-05-01

    Asymmetric X-ray emission and a powerful cluster-scale radio halo indicate that A2319 is a merging cluster of galaxies. This paper presents our multicolor photometry for A2319 with 15 optical intermediate filters in the Beijing-Arizona-Taiwan-Connecticut (BATC) system. There are 142 galaxies with known spectroscopic redshifts within the viewing field of 58' × 58' centered on this rich cluster, including 128 member galaxies (called sample I). A large velocity dispersion in the rest frame, 1622^{+91}_{-70} km s-1, suggests merger dynamics in A2319. The contour map of projected density and localized velocity structure confirm the so-called A2319B substructure, at ~10' northwest to the main concentration A2319A. The spectral energy distributions (SEDs) of more than 30,000 sources are obtained in our BATC photometry down to V ~ 20 mag. A u-band (~3551 Å) image with better seeing and spatial resolution, obtained with the Bok 2.3 m telescope at Kitt Peak, is taken to make star-galaxy separation and distinguish the overlapping contamination in the BATC aperture photometry. With color-color diagrams and photometric redshift technique, 233 galaxies brighter than h BATC = 19.0 are newly selected as member candidates after an exclusion of false candidates with contaminated BATC SEDs by eyeball-checking the u-band Bok image. The early-type galaxies are found to follow a tight color-magnitude correlation. Based on sample I and the enlarged sample of member galaxies (called sample II), subcluster A2319B is confirmed. The star formation properties of cluster galaxies are derived with the evolutionary synthesis model, PEGASE, assuming a Salpeter initial mass function and an exponentially decreasing star formation rate (SFR). A strong environmental effect on star formation histories is found in the manner that galaxies in the sparse regions have various star formation histories, while galaxies in the dense regions are found to have shorter SFR time scales, older stellar ages, and higher interstellar medium metallicities. For the merging cluster A2319, local surface density is a better environmental indicator rather than the cluster-centric distance. Compared with the well-relaxed cluster A2589, a higher fraction of star-forming galaxies is found in A2319, indicating that the galaxy-scale turbulence stimulated by the subcluster merger might have played a role in triggering the star formation activity.

  19. Calibration of Synthetic Photometry for B and early-A Stars

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, E. L.; Massa, D.

    2002-06-01

    We have developed a procedure for modeling the observed energy distributions of early-type stars (Teff ~ 10000 - 30000 K) over a wavelength range spanning the UV through the near-IR. The analysis relies on line-blanketed model atmospheres, as computed with R.L. Kurucz's ATLAS9 program, and a parametrized representation of the wavelength-dependent effects of interstellar extinction. With this technique, study of a stellar energy distribution --- even if severely reddened --- can reveal the basic properties of the star (Teff, log g, and [m/H]), as well as E(B-V), the shape of the interstellar extinction curve, and R = AV/E(B-V). The primary dataset to be exploited using this method is the Final Archive of the International Ultraviolet Explorer (IUE) satellite, which contains UV spectrophotometric observations (1200 - 3200Å) for hundreds of early-type stars over a wide range of reddenings, including eclipsing binary systems, open cluster members, and field stars. Unfortunately the wavelength range of these UV data does not include critical diagnostic information needed for determining, in particular, stellar surface gravity and extinction curve normalization. These diagnostics are located in the visible and near-IR portions of the spectrum and thus, to realize the full potential of our analysis, we need to supplement the IUE data with optical and near-IR measurements. The most widespread body of such data are Johnson UBVRIJHKL and Stromgren uvby + H? photometry. The problem is how to calibrate synthetic Johnson and Stromgren photometry of stellar model fluxes so that it can be compared with real stellar observations. In this poster we illustrate our procedure for calibrating synthetic Johnson and Stromgren photometry for early-type stars. We utilize a calibration sample of ~50 well-observed, lightly reddened A and B stars whose physical properties can be constrained by a combination of Hipparcos distances and stellar interior models. We discuss the results of the calibration process and demonstrate the energy distribution fitting procedure for a number of reddened and unreddened stars. Future applications of the analysis are noted. This work is supported by Astrophysics Data Program grant NAG5-7113 to Villanova University.

  20. Affect of including satellite observed land surface conditions on the modeled energy and water budgets of the Murray-Darling basin Australia

    NASA Astrophysics Data System (ADS)

    Evans, J. P.; McCabe, M. F.; Meng, X.

    2012-12-01

    A regional climate model (RCM) based on WRF was used to simulate the regional climate and assess the water and energy budgets over the Murray-Darling basin, a former GEWEX Regional Hydroclimate Project. In the default set-up land surface albedo and vegetation fraction are prescribed using a monthly varying climatology, thus eliminating any inter-annual variability in these surface conditions. From 2002 through 2007 South-east Australia, including the Murray-Darling basin, experienced a sever drought. Satellite observed surface conditions (albedo and vegetation fraction) demonstrated significant inter-annual variation through this period. By performing a RCM simulation using the observed changes in surface conditions, instead of the default climatology, basin-wide changes in water and energy budgets are quantified.

  1. Photometry and spectroscopy in the open cluster alpha Persei, 2.

    NASA Technical Reports Server (NTRS)

    Prosser, Charles F.

    1994-01-01

    Results from a combination of new spectroscopic and photometric observations in the lower main sequence and pre-main sequence of the open cluster alpha Persei are presented. New echelle spectroscopy has provided radial and rotational velocity information for thirteen candidate members, three of which are nonmembers based on radial velocity, absence of a Li 6707 A feature, and absence of H alpha emission. A set of revised rotational velocity estimates for several slowly rotating candidates identified earlier is given, yielding rotational velocities as low as 7 km/s for two apparent cluster members. VI photometry for several pre-main-sequence members is given; the new (V, V-I(sub K) photometry yields a more clearly defined pre-main sequence. A list of approximately 30 new faint candidate members based on the (V, V-I(sub K)), charge coupled device (CCD) photometry is presented in an effort to identify additional cluster members at very low masses. Low-dispersion spectra obtained for several of these candidates provide in some cases supporting evidence for cluster membership. The single brown dwarf candidate in this cluster is for the first time placed in a color-magnitude diagram with other cluster members, providing a better means for establishing its true status. Stars from among the list of new photometric candidates may provide the means for establishing a sequence of cluster members down to very faint magnitudes (V approximately 21) and consequently very low masses. New coordinate determinations for previous candidate members and finding charts for the new photometric candidates are provided in Appendices.

  2. MOST photometry of the enigmatic PMS pulsator HD 142666

    NASA Astrophysics Data System (ADS)

    Zwintz, K.; Kallinger, T.; Guenther, D. B.; Gruberbauer, M.; Huber, D.; Rowe, J.; Kuschnig, R.; Weiss, W. W.; Matthews, J. M.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Walker, G. A. H.; Casey, M. P.

    2009-02-01

    Context: Modeling of pre-main sequence (PMS) stars through asteroseismology of PMS p-mode pulsators has only recently become possible, and spacebased photometry is one of the important sources of data for these efforts. We present precise photometry of the pulsating Herbig Ae star HD 142666 obtained in two consecutive years with the MOST (Microvariability & Oscilations of STars) satellite. Aims: Previously, only a single pulsation period was known for HD 142666. The MOST photometry reveals that HD 142666 is multi-periodic. However, the unique identification of pulsation frequencies is complicated by the presence of irregular variability caused by the star's circumstellar dust disk. The two light curves obtained with MOST in 2006 and 2007 provided data of unprecedented quality to study the pulsations in HD 142666 and also to monitor the circumstellar variability. Methods: Frequency analysis was performed using the routine sigspec and the results from the 2006 and 2007 campaigns were then compared to each other with the software cinderella to identify frequencies common to both light curves. The correlated frequencies were then submitted to an asteroseismic analysis. Results: We attribute 12 frequencies to pulsation. Model fits to the three frequencies with the highest amplitudes lie well outside the uncertainty box for the star's position in the HR diagram based on published values. Some of the frequencies appear to be rotationally split modes. Conclusions: The models suggest that either (1) the published estimate of the luminosity of HD 142666, based on a relation between circumstellar disk radius and stellar luminosity, is too high and/or (2) additional physics such as mass accretion may be needed in our models to accurately fit both the observed frequencies and HD 142666's position in the HR diagram. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia with the assistance of the University of Vienna.

  3. Photometry and spectroscopy in the open cluster Alpha Persei, 2

    NASA Technical Reports Server (NTRS)

    Prosser, Charles F.

    1993-01-01

    Results from a combination of new spectroscopic and photometric observations in the lower main-sequence and pre-main sequence of the open cluster alpha Persei are presented. New echelle spectroscopy has provided radial and rotational velocity information for thirteen candidate members, three of which are nonmembers based on radial velocity, absence of a Li 6707A feature, and absence of H-alpha emission. A set of revised rotational velocity estimates for several slowly rotating candidates identified earlier is given, yielding rotational velocities as low as 7 km/s for two apparent cluster members. VRI photometry for several pre-main sequence members is given; the new (V,V-I(sub K)) photometry yields a more clearly defined pre-main sequence. A list of approximately 43 new faint candidate members based on the (V,V-I(sub K)) CCD photometry is presented in an effort to identify additional cluster members at very low masses. Low-dispersion spectra obtained for several of these candidates provide in some cases supporting evidence for cluster membership. The single brown dwarf candidate in this cluster is for the first time placed in a color-magnitude diagram with other cluster members, providing a better means for establishing its true status. Stars from among the list of new photometric candidates may provide the means for establishing a sequence of cluster members down to very faint magnitudes (V approximately 21) and consequently very low masses. New coordinate determinations for previous candidate members and finding charts for the new photometric candidates are provided in appendices.

  4. a necessary consequence of Titan's widely varying seasonal insola-tion, will affect the magnitude of the surface sensible heat flux

    E-print Network

    Cai, Long

    a necessary consequence of Titan's widely varying seasonal insola- tion, will affect the magnitude lapse rate is close to the boundary between stability and instability, as has been measured on Titan13 will not occur. At the time of our observations, Titan was approaching southern summer solstice, and, owing

  5. Extreme Ultraviolet Explorer Photometry of RS Canum Venaticorum Systems: Four Flaring Megaseconds

    NASA Astrophysics Data System (ADS)

    Osten, Rachel A.; Brown, Alexander

    1999-04-01

    We present an analysis of 12.2 Ms of Extreme Ultraviolet Explorer (EUVE) photometry of 16 RS CVn systems (including four flaring megaseconds). Our study attempts a systematic categorization of stellar coronal emission in RS CVn binary systems. The temporal resolution of the EUVE satellite and the opportunity for long observations enables us to study separately the quiescent and flaring states of RS CVn systems. Thirty of 31 observations are statistically variable. We examine light curves, characterizing both phase-dependent variations and large- and small-scale flaring. There is evidence for small-scale stochastic variability on the one short-period (Porb<1 day) system in our sample (ER Vul), which we interpret as small-scale flaring. CF Tuc is the only system for which phase-dependent variations over multiple orbital periods are seen. We analyze 30 flares on nine systems, fitting rise and decay times. Several flares have durations >0.5Porb and thus cannot originate from compact emission regions close to the stellar surfaces. Many flares have unusual flare morphologies, with rise times comparable to or greater than the decay time, and emission plateaus. In addition, eight flares have decay phases that are fit better by a broken power law than a single power law. The decay times for the second power law are statistically different than the single decay times and are correlated with the flare rise times. This observed connection points to the potential importance of the change in decay rate as a means of examining the physical processes operating during the flare. The distribution of orbital phases of flare onsets on V711 Tau (HR 1099), the best-studied RS CVn in our sample, is consistent with a Poisson distribution that is random in time. In two systems that are partially eclipsing (CF Tuc and ER Vul), we find no evidence for an eclipse in the light curve, indicating that the emission region is large compared to the stellar radius. We parameterize the distribution of flare energies as a power law, finding a cut-off energy of ~1033 ergs and a slope of -0.6. Flare energy increases with flare duration as E~?t1.42, confirming the long-duration nature of high-energy flares on RS CVn systems. The integrated flare luminosity depends on the quiescent luminosity as Lflare~L1.05quiescent. Flare frequencies range from 0.1 day-1 to 1.5 day-1. For observations not affected by the dead spot on the Deep Survey detector, 40% of the observed time was spent in a flaring state, indicating that flaring is a ``normal'' state for the coronae of these systems. We note the presence of a quasi-periodicity in EUVE photometric data on the order of 1 day, which is not corrected for in the standard reduction and analysis software.

  6. Coordinates and RI photometry of Large Magellanic Cloud carbon stars

    SciTech Connect

    Costa, E. (Universidad de Chile, Santiago (Chile))

    1990-07-01

    Coordinates and photoelectric RI magnitudes are given for 86 carbon stars discovered by Blanco et al. in four selected 0.12 deg sq areas of the LMC. A comparison with the photometry of Blanco et al. for carbon stars in three different fields of the LMC suggests that the luminosity distribution of the carbon stars may change from center to center in the LMC. This possibility is supported by the differences in the mean I magnitude of the carbon stars detected between the four areas studied. 16 refs.

  7. CCD-photometry of comets at large heliocentric distances

    NASA Technical Reports Server (NTRS)

    Mueller, Beatrice E. A.

    1992-01-01

    CCD imaging and time series photometry are used to determine the state of activity, nuclear properties and eventually the rotational motion of cometary nuclei. Cometary activity at large heliocentric distances and mantle evolution are not yet fully understood. Results of observations carried out at the 2.1 telescope on Kitt Peak April 10-12 and May 15-16, 1991 are discussed. Color values and color-color diagrams are presented for several comets and asteroids. Estimations of nuclear radii and shapes are given.

  8. 15 colour photometry of Landolt SA95 standard star field

    E-print Network

    Xu Zhou; Zhaoji Jiang; Jun Ma; Suijian Xue; Hong Wu; Jiansheng Chen; Jin Zhu; Weihsin Sun; Rogier A. Windhorst

    2002-09-23

    In this paper, we present a set of photometric observations in 15 colors of stars in the Landolt covered by the system range from 300 nm to 1000 nm. Visual magnitudes of the stars being studied in the field are from 10th to 20th mag. The observational methodology and the data reduction procedures are described. The relationships between the BATC intermediate-band system and the Landolt UBVRI broad band system are obtained. A catalogue of the photometry has been produced which contains the SEDs of 3613 stars. The electronic form of this catalogue can be accessed at the CDS via anonymous ftp to cdsarc.u-strasbg.fr.

  9. CCD based phase resolved stroboscopic photometry of pulsars

    E-print Network

    Jurij Kotar; Simon Vidrih; Andrej Cadez

    2003-03-17

    A stroboscope designed to observe pulsars in the optical spectrum is presented. The absolute phase of the stroboscope is synchronized to better than 2.5 microseconds with the known radio ephemerides for a given pulsar. The absolute timing is provided by the GPS clock. With such a device phase resolved photometry of pulsars can be performed. We demonstrate the instrument's capabilities with the results of a set of observations of the Crab pulsar, the brightest of the known optical pulsars, with a visual magnitude of 16.5, and a rotational frequency of ~29Hz.

  10. CCD photometry of the old open cluster Collinder 261

    E-print Network

    E. Gozzoli; M. Tosi; G. Marconi; A. Bragaglia

    1996-07-16

    We present UBVI photometry for the old open cluster Collinder 261. From comparison of the observed colour-magnitude diagrams with simulations based on stellar evolutionary models we derive in a self consistent way reddening, distance, and age of the cluster: E(B-V)=0.25$-$0.34, (m-M)$_0$=11.7-12.0, and age=7$-$8 Gyr or 9$-$11 Gyr, depending on the adopted stellar tracks. The models in better agreement with the data turn out to have metallicity at most solar.

  11. Old open clusters: UBGVRI photometry of NGC 2506

    E-print Network

    G. Marconi; D. Hamilton; M. Tosi; A. Bragaglia

    1997-07-07

    UBGVRI photometry for the open cluster NGC 2506 is presented. From comparison of the observed colour-magnitude diagrams with simulations based on stellar evolutionary models we derive in a self consistent way reddening, distance, and age of the cluster: E(B-V)=0-0.07, (m-M)o = 12.6, age = 1.5-2.2 Gyr. The cluster shows a well definite secondary sequence, suggesting that binary systems constitute about 20 % of the cluster members visible in the colour-magnitude diagram.

  12. CCD Photometry of Dwarf Nova AL Com in Superoutburst

    E-print Network

    W. Pych; A. Olech

    1995-09-20

    We report a CCD optical photometry of a dwarf nova AL Com in superoutburst. Before superhumps occurred the light curve was highly variable with dominant periods about 41 minutes and 81.5 minutes for different nights. The period of observed superhumps is 82.5 minutes and seems to be stable. The first harmonic of the basic period is also present. We detected a weak signal corresponding to period 78.1 minutes. One of the periods 78.1 or 81.5 is suspected to be a possible signature of orbital motion in the system.

  13. Spectroscopy and photometry for low-mass stars in Praesepe

    NASA Technical Reports Server (NTRS)

    Williams, Scott D.; Stauffer, John R.; Prosser, Charles F.; Herter, Terry

    1994-01-01

    We have obtained spectral types, H alpha equivalent widths, and optical photometry for a small sample of late K and M dwarf candidate members of the Praesepe open cluster. At least for the small sample of stars we have observed, all of the Paesepe members later than M2 have H alpha in emission. The chromospheric activity of the Praesepe satrs is essentially the same as that for Hyades members of the same mass, as expected since the two clusters are thought to be the same age.

  14. 5-micron photometry of late-type dwarfs

    E-print Network

    I. N. Reid; K. L. Cruz

    2001-10-15

    We present narrowband-M photometry of nine low-mass dwarfs with spectral types ranging from M2.5 to L0.5. Combining the (L'-M') colours derived from our observations with data from the literature, we find colours consistent with a Rayleigh-Jeans flux distribution for spectral types earlier than M5, but enhanced F_3.8/F_4.7 flux ratios (negative (L'-M') colours) at later spectral types. This probably reflects increased absorption at M' due to the CO fundamental band. We compare our results against recent model predictions and briefly discuss the implications.

  15. Photometry of resolved galaxies. IV - Holmberg I and Holmberg II

    NASA Technical Reports Server (NTRS)

    Hoessel, J. G.; Danielson, G. E.

    1984-01-01

    Colors and magnitudes are presented for 279 resolved stars in the Holmberg I dwarf galaxy and 468 resolved stars in Holmberg II. Both systems are Magellanic type dwarf members of the M81-NGC 2403 Group, which lies at approximately 3 Mpc from the Local Group. The photometry was done in the GRI passbands using CCD detectors. Color-magnitude diagrams and luminosity functions are constructed; these are compared with results for several Local Group galaxies and with theoretical work. Holmberg I is found to have a low present star formation rate, while Holmberg II is very active at present.

  16. CCD-Delta a and BVR photometry of NGC 7296

    E-print Network

    M. Netopil; E. Paunzen; H. M. Maitzen; A. Claret; K. Pavlovski; E. Tamajo

    2005-07-25

    The first CCD photometric investigation of the open cluster NGC 7296 up to now was performed within the narrow band Delta a photometric system, which enables us to detect peculiar objects. A deeper investigation of that cluster followed, using the standard BVR-Bessel filter set. The age and E(B-V) was determined independently to log t= 8.0 and 0.15 respectively by using Delta a and broadband photometry. In total five Be/Ae objects and two metal-weak stars showing significant negative Delta a-values as well as one classical chemically peculiar star could be identified within that intermediate age open cluster.

  17. EUVE photometry of SS Cygni: Dwarf nova outbursts and oscillations

    SciTech Connect

    Mauche, C.W.

    1995-05-15

    The authors present EUVE Deep Survey photometry and AAVSO optical measurements of the 1993 August and 1994 June/July outbursts of the dwarf nova SS Cygni. The EUV and optical light curves are used to illustrate the different response of the accretion disk to outbursts which begin at the inner edge and propagate outward, and those which begin at the outer edge and propagate inward. Furthermore, the authors describe the properties of the quasi-coherent 7--9 s sinusoidal oscillations in the EUV flux detected during the rise and plateau stages of these outbursts.

  18. Analysis of RGU Photometry in Selected Area 51

    Microsoft Academic Search

    S. Bilir; S. Karaali; R. Buser

    2004-01-01

    A low-latitude anticenter field (l=189 °, b=+21 °) is investigated by using the full calibration tools of RGU photometry. The observed RGU data are reduced to the standard system and the separation of dwarfs and evolved stars is carried out by an empirical method. Stars are categorized into three metallicity classes, i.e. -0.25<[M\\/H]<=+0.50, $-1.00<[M\\/H]<=-0.25, and [M\\/H]<=-1.00 dex, and their absolute

  19. LEMON: an (almost) completely automated differential-photometry pipeline

    NASA Astrophysics Data System (ADS)

    Terrón, V.; Fernández, M.

    2011-11-01

    We present LEMON, the CCD differential-photometry pipeline, written in Python, developed at the Institute of Astrophysics of Andalusia (CSIC) and originally designed for its use at the 1.23 m CAHA telescope for automated variable stars detection and analysis. The aim of our tool is to make it possible to completely reduce thousands of images of time series in a matter of hours and with minimal user interaction, if not none at all, automatically detecting variable stars and presenting the results to the astronomer.

  20. Broadband Photometry of the Potentially Hazardous Asteroid 2013 RH74

    NASA Astrophysics Data System (ADS)

    Hicks, M.; Ebelhar, S.

    2013-11-01

    The Near-Earth Asteroid (NEA) 2013 RH74 was discovered by the Catalina Sky Survey on September 15 2013 (MPEC 2013-S15) and has been designated as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center. We obtained six partial nights of broadband Bessel BVRI photometry at the JPL Table Mountain 0.6-m telescope (TMO), as summarized in Table 1. This object was detected by planetary radar soon after discovery (http://echo.jpl.nasa.gov/asteroids/index.html).

  1. Broadband Photometry of the Potentially Hazardous Asteroid 251346 (2007 SJ)

    NASA Astrophysics Data System (ADS)

    Hicks, M.; Ebelhar, S.

    2014-01-01

    The Near-Earth Asteroid (NEA) 251346 (2007 SJ) was discovered by the LINEAR Sky Survey on September 17, 2007 (MPEC 2007-S17). With a Minimum Orbit Intersection Distance (MOID) of 0.045 AU and an expected diameter between 1.3~2.8 km, this object has been designated as a Potentially Hazardous Asteroid (PHA) by the Minor Planet Center. We obtained two partial nights of broadband Bessel BVRI photometry (October 10 and December 11, 2013) and one night (December 13, 2013) at the JPL Table Mountain 0.6-m telescope (TMO), as summarized in Table 1.

  2. Optical photometry and spectroscopy of Nova Del 2013

    NASA Astrophysics Data System (ADS)

    Tomov, T.; Ilkiewicz, K.; Swierczynski, E.; Belcheva, M.; Dimitrov, D.

    2013-08-01

    We report optical BV photometry and spectroscopy of Nova Del 2013, carried out between August 14.88 UT and August 15.08 UT. Using a 60 cm Cassegrain telescope at the Nicolaus Copernicus University Observatory (Torun, Poland) we estimated the V brightness of the Nova to be 6.31+/-0.02 mag and 6.18+/-0.03 mag on Aug. 14.94 UT and Aug. 15.02 UT respectively. HD 194113 (F2, V=8.00 mag) was used as a comparison star.

  3. Near-IR Spectroscopy and Visual Broadband Photometry of Unbound Asteroid Pairs

    NASA Astrophysics Data System (ADS)

    Wolters, Stephen D.; Weissman, P.; Duddy, S. R.; Christou, A.; Green, S. F.; Lowry, S. C.; Rozitis, B.

    2012-10-01

    Over 62 pairs of asteroids have been identified with extremely similar orbits (Rozek, Breiter, and Jopek 2011, MNRAS 412, 987). Backwards integration of their orbits show that each pair probably experienced a very low-velocity close encounter, in many cases less than 1 Myr ago (e.g. Vokrouhlický and Nesvorný 2008, AJ 136, 280). Pravec et al. (2010, Nature, 466, 1085) examined 35 pairs and found that the secondary/primary mass ratio is <0.2. Also, as this ratio approaches 0.2, the rotation period of the primary increases. This is consistent with formation of the pairs through rotational fission of a parent rubble-pile asteroid (Scheeres 2007, Icarus 189, 370). However, the pairs were linked through dynamical considerations alone, and mass ratios were determined using catalogued visual magnitudes and the assumption that the albedos and bulk densities of the components are identical. We are undertaking a campaign of characterising the asteroids in these pairs using visual and NIR spectroscopy as well as thermal IR photometry. We present 0.8-2.5 micron spectroscopic observations of using SpeX on NASA-IRTF, and BVRI photometry using the 0.6-m Table Mountain Observatory telescope. Our goals are to assess the similarity of the spectra of the components’ surfaces (e.g. Duddy et al. 2012, A&A, 539, A36) and also to look for evidence of color variation as a function of rotational phase. Since dynamical studies have placed constraints on the formation ages, if the asteroids are completely resurfaced during formation, we can start to explore the timescales involved in space weathering. We report recent progress in our investigations. This work was supported in part by the NASA Planetary Astronomy Program and done in part at the Jet Propulsion Laboratory under contract with NASA.

  4. Boundary-Layer Transition on Hollow Cylinders in Supersonic Free Flight as Affected by Mach Number and a Screwthread Type of Surface Roughness

    NASA Technical Reports Server (NTRS)

    James, Carlton S.

    1959-01-01

    The effects of Mach number and surface-roughness variation on boundary-layer transition were studied using fin-stabilized hollow-tube models in free flight. The tests were conducted over the Mach number range from 2.8 to 7 at a nominally constant unit Reynolds number of 3 million per inch, and with heat transfer to the model surface. A screwthread type of distributed two-dimensional roughness was used. Nominal thread heights varied from 100 microinches to 2100 microinches. Transition Reynolds number was found to increase with increasing Mach number at a rate depending simultaneously on Mach number and roughness height. The laminar boundary layer was found to tolerate increasing amounts of roughness as Mach number increased. For a given Mach number an optimum roughness height was found which gave a maximum laminar run greater than was obtained with a smooth surface.

  5. UBV Photometry of the young open cluster Berkely 87

    NASA Astrophysics Data System (ADS)

    Akinyemi, Abolaji; Eskridge, Paul B.

    2015-01-01

    We obtained UBV imaging of a field in the young open cluster Berkeley 87. From these images, we measured the brightness of ~180 stars in the cluster. Our photometry was calibrated using published photometry (Turner & Forbes 1982 PASP 94, 789) of a subset of stars in our field. The cluster is in a region of the sky with strongly varying extinction. Therefore we made a (U-B)-(B-V) color-color diagram of the field and used this to de-redden the stars on a case by case basis. We de-reddened the stars using the unreddened supergiant and main sequence colors from Astrophysical Quantities (Cox 2000).The color-magnitude diagrams of the de-reddened stars are compared to the Padova isochrones(Marigo et al 2008 A&A 482 883). The isochrones are generated for a range of ages, with solar metalicity and no ? enhancement. The best fit for the isochrones was the main sequence de-reddened stars from which the age of the cluster is estimated to be 20 million years. This is older than previous age estimates (1-5 million years) from earlier studies of the cluster. This may indicate age variation in the cluster.We acknowledge the support of the Physics and Astronomy department, and the College of Science and Engineering, Minnesota State University, Mankato.

  6. PHOTOMETRY OF VARIABLE STARS FROM DOME A, ANTARCTICA

    SciTech Connect

    Wang Lingzhi [Department of Astronomy, Beijing Normal University, Beijing 100875 (China); Macri, Lucas M.; Krisciunas, Kevin; Wang Lifan [Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Ashley, Michael C. B.; Lawrence, Jon S.; Luong-Van, Daniel; Storey, John W. V. [School of Physics, University of New South Wales, NSW 2052 (Australia); Cui Xiangqun; Gong Xuefei; Yuan Xiangyan [Nanjing Institute of Astronomical Optics and Technology, Nanjing 210042 (China); Feng Longlong; Yang Ji; Zhu Zhenxi [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Liu Qiang; Zhou Xu [National Astronomical Observatory of China, Chinese Academy of Sciences, Beijing 100012 (China); Pennypacker, Carl R. [Center for Astrophysics, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Shang Zhaohui [Department of Physics, Tianjin Normal University, Tianjin 300074 (China); Yang Huigen [Polar Research Institute of China, Pudong, Shanghai 200136 (China); York, Donald G. [Department of Astronomy and Astrophysics and Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)

    2011-11-15

    Dome A on the Antarctic plateau is likely one of the best observing sites on Earth thanks to the excellent atmospheric conditions present at the site during the long polar winter night. We present high-cadence time-series aperture photometry of 10,000 stars with i < 14.5 mag located in a 23 deg{sup 2} region centered on the south celestial pole. The photometry was obtained with one of the CSTAR telescopes during 128 days of the 2008 Antarctic winter. We used this photometric data set to derive site statistics for Dome A and to search for variable stars. Thanks to the nearly uninterrupted synoptic coverage, we found six times as many variables as previous surveys with similar magnitude limits. We detected 157 variable stars, of which 55% were unclassified, 27% were likely binaries, and 17% were likely pulsating stars. The latter category includes {delta} Scuti, {gamma} Doradus, and RR Lyrae variables. One variable may be a transiting exoplanet.

  7. Macular Pigment Optical Density Measured by Heterochromatic Modulation Photometry

    PubMed Central

    Huchzermeyer, Cord; Schlomberg, Juliane; Welge-Lüssen, Ulrich; Berendschot, Tos T. J. M.; Pokorny, Joel; Kremers, Jan

    2014-01-01

    Purpose To psychophysically determine macular pigment optical density (MPOD) employing the heterochromatic modulation photometry (HMP) paradigm by estimating 460 nm absorption at central and peripheral retinal locations. Methods For the HMP measurements, two lights (B: 460 nm and R: 660 nm) were presented in a test field and were modulated in counterphase at medium or high frequencies. The contrasts of the two lights were varied in tandem to determine flicker detection thresholds. Detection thresholds were measured for different R:B modulation ratios. The modulation ratio with minimal sensitivity (maximal threshold) is the point of equiluminance. Measurements were performed in 25 normal subjects (11 male, 14 female; age: 30±11 years, mean ± sd) using an eight channel LED stimulator with Maxwellian view optics. The results were compared with those from two published techniques – one based on heterochromatic flicker photometry (Macular Densitometer) and the other on fundus reflectometry (MPR). Results We were able to estimate MPOD with HMP using a modified theoretical model that was fitted to the HMP data. The resultant MPODHMP values correlated significantly with the MPODMPR values and with the MPODHFP values obtained at 0.25° and 0.5° retinal eccentricity. Conclusions HMP is a flicker-based method with measurements taken at a constant mean chromaticity and luminance. The data can be well fit by a model that allows all data points to contribute to the photometric equality estimate. Therefore, we think that HMP may be a useful method for MPOD measurements, in basic and clinical vision experiments. PMID:25354049

  8. A new look at photometry of the Moon

    USGS Publications Warehouse

    Goguen, J.D.; Stone, T.C.; Kieffer, H.H.; Buratti, B.J.

    2010-01-01

    We use ROLO photometry (Kieffer, H.H., Stone, T.C. [2005]. Astron. J. 129, 2887-2901) to characterize the before and after full Moon radiance variation for a typical highlands site and a typical mare site. Focusing on the phase angle range 45??. ) to calculate the scattering matrix and solve the radiative transfer equation for I/. F. The mean single scattering albedo is ??=0.808, the asymmetry parameter is ???cos. ?????=0.77 and the phase function is very strongly peaked in both the forward and backward scattering directions. The fit to the observations for the highland site is excellent and multiply scattered photons contribute 80% of I/. F. We conclude that either model, roughness or multiple scattering, can match the observations, but that the strongly anisotropic phase functions of realistic particles require rigorous calculation of many orders of scattering or spurious photometric roughness estimates are guaranteed. Our multiple scattering calculation is the first to combine: (1) a regolith model matched to the measured particle size distribution and index of refraction of the lunar soil, (2) a rigorous calculation of the particle phase function and solution of the radiative transfer equation, and (3) application to lunar photometry with absolute radiance calibration. ?? 2010 Elsevier Inc.

  9. Photometry of Variable Stars from Dome A, Antarctica

    E-print Network

    Wang, Lingzhi; Krisciunas, Kevin; Wang, Lifan; Ashley, Michael C B; Cui, Xiangqun; Feng, Long-Long; Gong, Xuefei; Lawrence, Jon S; Liu, Qiang; Luong-Van, Daniel; Pennypacker, Carl R; Shang, Zhaohui; Storey, John W V; Yang, Huigen; Yang, Ji; Yuan, Xiangyan; York, Donald G; Zhou, Xu; Zhu, Zhenxi

    2011-01-01

    Dome A on the Antarctic plateau is likely one of the best observing sites on Earth thanks to the excellent atmospheric conditions present at the site during the long polar winter night. We present high-cadence time-series aperture photometry of 10,000 stars with i<14.5 mag located in a 23 square-degree region centered on the south celestial pole. The photometry was obtained with one of the CSTAR telescopes during 128 days of the 2008 Antarctic winter. We used this photometric data set to derive site statistics for Dome A and to search for variable stars. Thanks to the nearly-uninterrupted synoptic coverage, we find 6 times as many variables as previous surveys with similar magnitude limits. We detected 157 variable stars, of which 55% are unclassified, 27% are likely binaries and 17% are likely pulsating stars. The latter category includes delta Scuti, gamma Doradus and RR Lyrae variables. One variable may be a transiting exoplanet.

  10. The important role of surface ligand on CdSe/CdS core/shell nanocrystals in affecting the efficiency of H2 photogeneration from water.

    PubMed

    Wang, Ping; Zhang, Jie; He, Haili; Xu, Xiaolong; Jin, Yongdong

    2015-03-19

    The use of colloidal semiconductor nanocrystals (NCs), especially those with a core/shell structure, for photocatalytic hydrogen (H2) production from water is currently one of the hottest research fields. Although the ligand on the semiconductor NC surface is crucial to the optical and optoelectronic properties of the NC, the study of the ligand effect on the photocatalytic activity of H2 generation is rarely reported. Herein, we employ nearly monodispersed CdSe/CdS core/shell NCs as a model photocatalytic system, and three kinds of ligands with different numbers of functional thiol groups (i.e., poly(acrylic acid), 3-mercaptopropionic acid and 2,3-dimercaptosuccinic acid) are selected as the ligands to investigate the effect of ligand on the efficiency of H2 photogeneration. The results show that the H2 photogeneration efficiency is highly dependent on the surface ligand of the NCs, and it increases with the increase of the number of the functional thiol groups in the ligand, and correspondingly, the photoluminescence intensity and average fluorescence lifetime, which are measured by steady state and time-resolved fluorescence measurements, are decreased. The surface trap-related charge separation efficiency, which is mediated by surface coating with different ligands, is supposed to cause the distinct ligand-dependent performance in the H2 evolution. PMID:25757912

  11. VizieR Online Data Catalog: CU Vir Stroemgren differential photometry (Pyper+, 2013)

    NASA Astrophysics Data System (ADS)

    Pyper, D. M.; Stevens, I. R.; Adelman, S. J.

    2014-06-01

    Our data are from two sources: Stroemgren differential uvby photometry obtained using the Four College Automated Photometric Telescope (FCAPT) originally on Mt. Hopkins, AZ, and later at Fairborn Observatory, Washington Camp, AZ, and photometry from the Solar Mass Ejection Imager (SMEI). (1 data file).

  12. The important role of surface ligand on CdSe/CdS core/shell nanocrystals in affecting the efficiency of H2 photogeneration from water

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Zhang, Jie; He, Haili; Xu, Xiaolong; Jin, Yongdong

    2015-03-01

    The use of colloidal semiconductor nanocrystals (NCs), especially those with a core/shell structure, for photocatalytic hydrogen (H2) production from water is currently one of the hottest research fields. Although the ligand on the semiconductor NC surface is crucial to the optical and optoelectronic properties of the NC, the study of the ligand effect on the photocatalytic activity of H2 generation is rarely reported. Herein, we employ nearly monodispersed CdSe/CdS core/shell NCs as a model photocatalytic system, and three kinds of ligands with different numbers of functional thiol groups (i.e., poly(acrylic acid), 3-mercaptopropionic acid and 2,3-dimercaptosuccinic acid) are selected as the ligands to investigate the effect of ligand on the efficiency of H2 photogeneration. The results show that the H2 photogeneration efficiency is highly dependent on the surface ligand of the NCs, and it increases with the increase of the number of the functional thiol groups in the ligand, and correspondingly, the photoluminescence intensity and average fluorescence lifetime, which are measured by steady state and time-resolved fluorescence measurements, are decreased. The surface trap-related charge separation efficiency, which is mediated by surface coating with different ligands, is supposed to cause the distinct ligand-dependent performance in the H2 evolution.The use of colloidal semiconductor nanocrystals (NCs), especially those with a core/shell structure, for photocatalytic hydrogen (H2) production from water is currently one of the hottest research fields. Although the ligand on the semiconductor NC surface is crucial to the optical and optoelectronic properties of the NC, the study of the ligand effect on the photocatalytic activity of H2 generation is rarely reported. Herein, we employ nearly monodispersed CdSe/CdS core/shell NCs as a model photocatalytic system, and three kinds of ligands with different numbers of functional thiol groups (i.e., poly(acrylic acid), 3-mercaptopropionic acid and 2,3-dimercaptosuccinic acid) are selected as the ligands to investigate the effect of ligand on the efficiency of H2 photogeneration. The results show that the H2 photogeneration efficiency is highly dependent on the surface ligand of the NCs, and it increases with the increase of the number of the functional thiol groups in the ligand, and correspondingly, the photoluminescence intensity and average fluorescence lifetime, which are measured by steady state and time-resolved fluorescence measurements, are decreased. The surface trap-related charge separation efficiency, which is mediated by surface coating with different ligands, is supposed to cause the distinct ligand-dependent performance in the H2 evolution. Electronic supplementary information (ESI) available: TEM image OA-capped CdSe/CdS core/shell NCs and corresponding size histograms; atomic ratio of sulfur/nickel and PL QY of QDs capped with different ligands (Table S1); PL decay fitting data (Table S2); UV-Vis results of the aqueous solution with Ni2+ ions with the varying concentration of DMSA; TEM images of the QDs capped with the three different ligands after the hydrogen evolution measurements using Pt as the catalyst. See DOI: 10.1039/c4nr07343f

  13. Response Surface Plots for the Behavioral Pattern of Yersinia enterocolitica in Chocolate Milk as Affected by Trans-Cinnamaldehyde, a Spice Essential Oil Constituent

    Microsoft Academic Search

    Kattathara H. Divya; Mandyam Chakravarathy Varadaraj

    Response surface plots were generated to determine the behavior of a native food isolate of Yersinia enterocolitica CFR 2301 in chocolate milk with added trans-cinnamaldehyde, an active spice essential oil constituent. The minimum inhibitory\\u000a and bactericidal concentrations (MIC and MBC) for Y. enterocolitica in broth systems were 0.1 and 0.3?µl\\/ml, respectively, while in chocolate milk, the MBC was 0.9?µl\\/ml. In

  14. Does small-scale vertical distribution of juvenile schooling fish affect prey availability to surface-feeding seabirds in the Wadden Sea?

    NASA Astrophysics Data System (ADS)

    Dänhardt, Andreas; Becker, Peter H.

    2011-02-01

    Food availability is a key variable influencing breeding performance and demography of marine top predators. Due to methodological problems, proportionality between fish abundance and availability is often assumed without being explicitly tested. More specifically, better breeding performance of surface-feeding seabirds at times of large prey stocks suggests that prey availability is also a function of prey abundance. Using vertically resolved stow net sampling we tested whether local abundance and length composition of pelagic fish are reliable predictors of the availability of these fish to surface-feeding Common Terns ( Sterna hirundo) breeding in the German Wadden Sea. Prey fish were found to concentrate below the maximum diving depth of the terns. Individuals caught close to the surface were in most cases smaller than conspecifics caught at greater depth. Correlations between fish abundance within and out of reach of the terns appeared to be both species- and site-specific rather than driven by overall fish abundance. Vertical distribution patterns of the terns' main prey fish could be explained as anti-predator behavior, reducing prey availability to the terns. In 2007, when breeding performance was much better than in 2006, herring and whiting were much more abundant, suggesting that overall prey abundance may also increase prey availability in habitats other than those represented by the stow net sampling.

  15. The impact of alkali pretreatment and post-pretreatment conditioning on the surface properties of rice straw affecting cellulose accessibility to cellulases.

    PubMed

    Karuna, Nardrapee; Zhang, Lu; Walton, Jeffrey H; Couturier, Marie; Oztop, Mecit H; Master, Emma R; McCarthy, Michael J; Jeoh, Tina

    2014-09-01

    Rice straw was pretreated with sodium hydroxide and subsequently conditioned to reduce the pH to 5-6 by either: (1) extensive water washing or (2) acidification with hydrochloric acid then water washing. Alkali pretreatment improved the enzymatic digestibility of rice straw by increasing the cellulose accessibility to cellulases. However, acidification after pretreatment reversed the gains in cellulose accessibility to cellulases and enzymatic digestibility due to precipitation of solubilized compounds. Surface composition analyses by ToF-SIMS confirmed a reduction in surface lignin by pretreatment and water washing, and suggested that acidification precipitated a chemically modified form of lignin on the surfaces of rice straw. The spin-spin relaxation times (T2) of the samples indicated increased porosity in alkali pretreated rice straw. The acidified pretreated rice straw had reduced amounts of water in the longer T2 proton pools associated with water in the pores of the biomass likely due to back-filling by the precipitated components. PMID:24983695

  16. Porous medium coffee ring effect and other factors affecting the first crystallisation time of sodium chloride at the surface of a drying porous medium

    NASA Astrophysics Data System (ADS)

    Hidri, F.; Sghaier, N.; Eloukabi, H.; Prat, M.; Nasrallah, S. Ben

    2013-12-01

    We study the distribution of ions in a drying porous medium up to the formation of first crystals at the surface. The study is based on comparisons between numerical simulations and experiments with packings of glass beads. The experimental configuration, which is representative of many previous drying experiments, is characterized by the formation of an efflorescence fairy ring at the surface of the porous medium. The preferential formation of crystals at the periphery is explained by the combined effect of higher evaporation fluxes at the surface periphery, as in the classical coffee ring problem, and variations in the porosity near the wall bordering the packing. It is shown that both effects have a great impact on the time marking the occurrence of first crystals, which is referred to as the first crystallization time. The experiments indicate that the first crystallization time increases with a decreasing bead size for a given initial ion concentration. This is explained by the variation with bead size of the characteristic size of the near wall region where a preferential desaturation of the sample occurs as a result of the porosity increase near the wall. The study also reveals a significant salt supersaturation effect. This represents a noticeable fact in relation with salt weathering issues.

  17. Time-series Photometry of the Pre-Main Sequence Binary V4046 Sgr: Testing the Accretion Stream Theory

    NASA Astrophysics Data System (ADS)

    Tofflemire, Benjamin M.; Mathieu, Robert D.; Ardila, David R.; Ciardi, David R.

    2015-01-01

    Most stars are born in binaries, and the evolution of protostellar disks in pre-main sequence (PMS) binary stars is a current frontier of star formation research. PMS binary stars can have up to three accretion disks: two circumstellar disks and a circumbinary disk separated by a dynamically cleared gap. Theory suggests that mass may periodically flow in an accretion stream from a circumbinary disk across the gap onto circumstellar disks or stellar surfaces. Thus, accretion in PMS binaries is controlled by not only radiation, disk viscosity, and magnetic fields, but also by orbital dynamics.As part of a larger, ongoing effort to characterize mass accretion in young binary systems, we test the predictions of the binary accretion stream theory through continuous, multi-orbit, multi-color optical and near-infrared (NIR) time-series photometry. Observations such as these are capable of detecting and characterizing these modulated accretion streams, if they are generally present. Broad-band blue and ultraviolet photometry trace the accretion luminosity and photospheric temperature while NIR photometry provide a measurement of warm circumstellar material, all as a function of orbital phase. The predicted phase and magnitude of enhanced accretion are highly dependent on the binary orbital parameters and as such, our campaign focuses on 10 PMS binaries of varying periods and eccentricities. Here we present multi-color optical (U, B,V, R), narrowband (H?), and multi-color NIR (J, H) lightcurves of the PMS binary V4046 Sgr (P=2.42 days) obtained with the SMARTS 1.3m telescope and LCOGT 1m telescope network. These results act to showcase the quality and breadth of data we have, or are currently obtaining, for each of the PMS binaries in our sample. With the full characterization of our sample, these observations will guide an extension of the accretion paradigm from single young stars to multiple systems.

  18. Interpreting Line Drawings as Three-Dimensional Surfaces

    Microsoft Academic Search

    Harry G. Barrow; Jay M. Tenenbaum

    1981-01-01

    Understanding how line drawings convey tri-dimensionality is of fundamental importance in explaining surface perception when photometry is either uninformative or too compex to model analytically. We put forward here a computational model for interpreting line drawings as three-dimensional surfaces, based on constraints on local surface orientation along extremal and discontinuity boun- daries. Specific techniques are described for two key processes

  19. Imaging and Narrowband Photometry of Comet 81P\\/Wild 2 in Support of the Stardust Spacecraft Encounter

    Microsoft Academic Search

    T. L. Farnham; D. G. Schleicher

    2002-01-01

    We will present results from our analysis of images and narrowband photometry of the Stardust spacecraft target comet 81P\\/Wild 2. We have images from 10 nights in 1997 and photometry from three apparitions: 4 nights in 1978, 5 nights in 1984 and 12 nights in 1997. All data were obtained at Lowell Observatory. For the photometry measurements, narrowband filters were

  20. PUSHING THE LIMITS OF GROUND-BASED PHOTOMETRIC PRECISION: SUBMILLIMAGNITUDE TIME-SERIES PHOTOMETRY OF THE OPEN CLUSTER NGC 6791

    E-print Network

    Gaudi, B. Scott

    PUSHING THE LIMITS OF GROUND-BASED PHOTOMETRIC PRECISION: SUBMILLIMAGNITUDE TIME-SERIES PHOTOMETRY of this study was to demonstrate the ability to obtain very high precision photometry for a large number to obtain high-precision (millimagnitude, or less than 1%) time-series, optical and infrared photometry

  1. VAPHOT -A Package for Precision Differential Aperture Photometry HANS J. DEEG1,2, LAURANCE R. DOYLE3

    E-print Network

    Deeg, Hans-Jörg

    VAPHOT - A Package for Precision Differential Aperture Photometry HANS J. DEEG1,2, LAURANCE R radius, diameter and 'size' is clarified Abstract The aperture photometry package `vaphot' was developed to perform reliable and precise time-series photometry of uncrowded fields. This package works within

  2. The First Multi-Colour Photometry of Three ASCC Clusters

    NASA Astrophysics Data System (ADS)

    Kiran, E.; Tas, G.

    In this work, we present the first comprehensive photometry of the three open clusters (ASCC 31, 111 and 112) listed in the open clusters catalogue published by Kharchenko et al. [2005]. Plotting the data in colour-magnitude and colour-colour diagrams, and using the main sequence fitting method we estimated the distance modules of 9.3, 10.62 and 9.7 and the distances 724, 1330 and 871 pc for ASCC 31, ASCC 111 and ASCC 112 clusters, respectively. Using theoretical isochrones taken from related literature (e.g. Schaerer et al. [1993]; Mowlavi et al. [1998]; Schaller et al. [1992]) we computed the ages as follows; in the order mentioned above log (t) = 9.14, 6.09 and 8.00 of these open clusters.

  3. BVRI CCD Photometry of Theta-1 Orionis A

    NASA Astrophysics Data System (ADS)

    Hopkins, J. L.; Lucas, G. A.

    2007-05-01

    Time-series BVRI CCD photometry data on Theta-1 Orionis A (V1016 ORI), a member of the familiar Trapezium cluster, was obtained at the Hopkins Phoenix Observatory (Phoenix, AZ) during December 2006 through February 2007. Data was acquired during two primary eclipse cycles, along with multiple out-of-eclipse observations. The observations were made with a Meade DSI Pro CCD camera and LX200 GPS 12 inch (30.5 cm) aperture telescope equipped with Johnson-Cousins filters. This paper details the observing setup, the technique, and resulting data analysis. It was noted that the estimated mid-eclipse (minimum light) point during the 02 December 2006 primary eclipse appears to have occurred several hours later than predicted from the early epoch timings. The possible secondary eclipse (which has evidently never been observed by anyone) proved to be elusive.

  4. Infrared Photometry of Asteroids Observed with the Spitzer Space Telescope

    NASA Astrophysics Data System (ADS)

    Bhattacharya, B.; Meadows, V. S.; Grillmair, C.; Ryan, E.; Burgdorf, M.; Rebull, L.; Tyler, S.; Noriega-Crespo, A.; Morris, P.; Tedesco, E.; Giorgini, J.

    2004-11-01

    We present photometric measurements of asteroids observed with the Spitzer Space Telescope. Photometry at 3.6, 4.5, 5.8, and 8.0 microns as well as at 24 microns using the IRAC and MIPS instruments is provided. We discuss time variability of flux for all known and newly identified asteroids in the Spitzer First Look Survey Ecliptic Plane Component. We also consider flux measurements and their implications on size estimation for known asteroids in the publicly available IRAC calibration data. The study presented here also demonstrates the usability of the JPL HORIZONS tool ISPY for identification of known asteroids in Spitzer fields. This work is based on observations made with the Spitzer Space Telescope, which is is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Support for this work was provided by NASA through an award issued by JPL/Caltech.

  5. The symbiosis of photometry and radial-velocity measurements

    NASA Technical Reports Server (NTRS)

    Cochran, William D.

    1994-01-01

    The FRESIP mission is optimized to detect the inner planets of a planetary system. According to the current paradigm of planet formation, these planets will probably be small Earth-sized objects. Ground-based radial-velocity programs now have the sensitivity to detect Jovian-mass planets in orbit around bright solar-type stars. We expect the more massive planets to form in the outer regions of a proto-stellar nebula. These two types of measurements will very nicely complement each other, as they have highest detection probability for very different types of planets. The combination of FRESIP photometry and ground-based spectra will provide independent confirmation of the existence of planetary systems in orbit around other stars. Such detection of both terrestrial and Jovian planets in orbit around the same star is essential to test our understanding of planet formation.

  6. FRAM telescope - monitoring of atmospheric extinction and variable star photometry

    NASA Astrophysics Data System (ADS)

    Jurysek, J.; Honkova, K.; Masek, M.

    2015-02-01

    The FRAM (F/(Ph)otometric Robotic Atmospheric Monitor) telescope is a part of the Pierre Auger Observatory (PAO) located near town Malargüe in Argentina. The main task of the FRAM telescope is the continuous night - time monitoring of the atmospheric extinction and its wavelength dependence. The current methodology of the measurement of a atmospheric extinction and for instrumentation properties also allows simultaneous observation of other interesting astronomical targets. The current observations of the FRAM telescope are focused on the photometry of eclipsing binaries, positional refinement of minor bodies of the Solar system and observations of optical counterparts of gamma ray bursts. In this contribution, we briefly describe the main purpose of the FRAM telescope for the PAO and we also present its current astrono mical observing program.

  7. Recovering The Photometry Of Brighter Than Saturated Objects In SDSS

    NASA Astrophysics Data System (ADS)

    Dahab, William

    2007-05-01

    We present the results of a technique that recovers the integrity of the SDSS photometry from bright (m < 15) and/or saturated objects in the SDSS. Bright objects saturate the CCD used by the SDSS, with overabundant electrons spilling over to nearby pixels, resulting in bleed trails. The photometric pipeline should, and indeed does, effectively process these bleed trails yielding usable data. This technique filters objects based on their specific flags, and recovers the stellar locus in color-color space. Objects as bright as g = 13 were extremely well recovered, as well as much of the data down to g = 11. We used these data to search for blue, saturated objects, hoping to find bright quasars. No new quasars were discovered, but several previously known objects, including 3C 273, were. We did discover a new cataclysmic variable, demonstrating the viability of this technique in the search for new, bright objects.

  8. USING PHOTOMETRY TO PROBE THE CIRCUMSTELLAR ENVIRONMENT OF {delta} SCORPII

    SciTech Connect

    Jones, C. E.; Wiegert, P. A.; Cyr, R. P.; Halonen, R. J. [Department of Physics and Astronomy, Western University, London, ON N6A 3K7 (Canada); Tycner, C. [Department of Physics, Central Michigan University, Mt. Pleasant, MI 48859 (United States); Henry, G. W.; Muterspaugh, M. W. [Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Blvd., Box No 9501, Nashville, TN 37209 (United States)

    2013-05-15

    We acquired Johnson BV photometry of the binary Be disk system {delta} Scorpii during its 2009, 2010, 2011, and 2012 observing seasons and used it to probe the innermost regions of the disk. We found that several disk building events have occurred during this time, resulting in an overall brightening in the V band and reddening of the system. In addition to these long-term trends, we found cyclical variability in each observing season on timescales between 60 and 100 days. We were able to reproduce the changes in the magnitude and color of {delta} Sco using our theoretical models and found that variable mass-loss rates in the range 2.5-7.0 Multiplication-Sign 10{sup -9} M{sub Sun} yr{sup -1} over {approx}35 days can reproduce the observed increase in brightness.

  9. New Metallicty Calibration for Dwarfs for the RGU-Photometry

    NASA Astrophysics Data System (ADS)

    Karaali, Salih; Bilir, Selçuk

    2002-10-01

    We adopted the procedure of Carney to obtain a metallicity calibration for dwarfs for the RGU photometry. For this purpose we selected 76 dwarfs of different metallicities from Carney, and Strobel et al., and evaluated their ?(U-G) ultra-violet excess relative to Hyades by transforming their UBV magnitudes to RGU via metallicity dependent equations of Ak-Güngör. The ?0.6/?M normalized factors of Sandage transform ?(U-G) excess at any G-R to ?=?1.08, i.e.: the ultra-violet excess at G-R = 1.08 mag, corresponding to B-V = 0.60 mag in the UBV-system. Finally, the (?, [Fe/H]) couples were fitted by the equation [Fe/H] = 0.11-2.22?-7.95?2. This calibration covers the metallicity interval (-2.20, +0.20) dex.

  10. An interactive modular design for computerized photometry in spectrochemical analysis

    NASA Technical Reports Server (NTRS)

    Bair, V. L.

    1980-01-01

    A general functional description of totally automatic photometry of emission spectra is not available for an operating environment in which the sample compositions and analysis procedures are low-volume and non-routine. The advantages of using an interactive approach to computer control in such an operating environment are demonstrated. This approach includes modular subroutines selected at multiple-option, menu-style decision points. This style of programming is used to trace elemental determinations, including the automated reading of spectrographic plates produced by a 3.4 m Ebert mount spectrograph using a dc-arc in an argon atmosphere. The simplified control logic and modular subroutine approach facilitates innovative research and program development, yet is easily adapted to routine tasks. Operator confidence and control are increased by the built-in options including degree of automation, amount of intermediate data printed out, amount of user prompting, and multidirectional decision points.

  11. Towards photometry pipeline of the Indonesian space surveillance system

    E-print Network

    Priyatikanto, R; Rachman, A; Dani, T

    2015-01-01

    Optical observation through sub-meter telescope equipped with CCD camera becomes alternative method for increasing orbital debris detection and surveillance. This observational mode is expected to eye medium-sized objects in higher orbits (e.g. MEO, GTO, GSO \\& GEO), beyond the reach of usual radar system. However, such observation of fast-moving objects demands special treatment and analysis technique. In this study, we performed photometric analysis of the satellite track images photographed using rehabilitated Schmidt Bima Sakti telescope in Bosscha Observatory. The Hough transformation was implemented to automatically detect linear streak from the images. From this analysis and comparison to USSPACECOM catalog, two satellites were identified and associated with inactive Thuraya-3 satellite and Satcom-3 debris which are located at geostationary orbit. Further aperture photometry analysis revealed the periodicity of tumbling Satcom-3 debris. In the near future, it is not impossible to apply similar sche...

  12. Physical studies of asteroids XVI - Photoelectric photometry of 17 asteroids

    NASA Astrophysics Data System (ADS)

    Lagerkvist, C.-I.; Hahn, G.; Magnusson, P.; Rickman, H.

    1987-07-01

    The authors present photoelectric photometry of 17 asteroids observed during the period 1979 - 1986. Composite lightcurves have been derived for 76, 236, 439, 516 and 591, and at least a reasonable single-lightcurve coverage has been obtained for the majority of the remaining ones. Reference is made to Tholen's (1984) taxonomic classification and a brief discussion of lightcurve statistics in this framework is given. Differences between the spin rates and amplitudes of the C, S and M classes are considered and previous conclusions regarding the peculiar characteristics of M asteroids are confirmed. An indication is found that C and S asteroids have a particularly slow spin when situated near the 3/1 or 5/2 Kirkwood gaps.

  13. Photoluminescence-excitation spectroscopy as a highly sensitive probe for carrier transport processes affected by surface damages in AlxGa1-xN/GaN heterostructures

    NASA Astrophysics Data System (ADS)

    Takeuchi, Hideo; Yamamoto, Yoshitsugu; Kamo, Yoshitaka; Kunii, Tetsuo; Oku, Tomoki; Shirahama, Takeo; Tanaka, Hiroyasu; Nakayama, Masaaki

    2007-08-01

    We demonstrate that photoluminescence-excitation (PLE) spectroscopy can probe with high sensitivity the effects of plasma-induced surface damages on photogenerated-carrier-transport processes in AlxGa1-xN/GaN heterostructures, on the basis of systematic optical and structural characterization results for the as-grown reference sample and the plasma-exposed sample. It is found from the structural characterizations with atomic force microscopy that the plasma exposure remarkably modifies the atomic step boundaries and the pits on the AlxGa1-xN surface, which leads to a remarkable difference between the PLE spectra of the bound exciton photoluminescence from the underlying GaN layer in the two samples. The PLE spectrum of the reference sample shows a step rising from the AlxGa1-xN fundamental transition energy toward the high energy side, whereas the rising step disappears in the PLE spectrum of the plasma-exposed sample. In contrast, the reflectance characteristics are the same in the two samples; i.e., the excitonic transition itself is not influenced by the plasma exposure. The present findings indicate that the PLE spectral profile is sensitive to the change in efficiency of the photogenerated carrier injection from the AlxGa1-xN layer to the GaN layer. Thus, it is concluded that the PLE characterization is effective to probe the photogenerated-carrier transport in heterostructures.

  14. Uptake and bio-reactivity of polystyrene nanoparticles is affected by surface modifications, ageing and LPS adsorption: in vitro studies on neural tissue cells.

    PubMed

    Murali, Kumarasamy; Kenesei, Kata; Li, Yang; Demeter, Kornél; Környei, Zsuzsanna; Madarász, Emilia

    2015-02-19

    Because of their capacity of crossing an intact blood-brain barrier and reaching the brain through an injured barrier or via the nasal epithelium, nanoparticles have been considered as vehicles to deliver drugs and as contrast materials for brain imaging. The potential neurotoxicity of nanoparticles, however, is not fully explored. Using particles with a biologically inert polystyrene core material, we investigated the role of the chemical composition of particle surfaces in the in vitro interaction with different neural cell types. PS NPs within a size-range of 45-70 nm influenced the metabolic activity of cells depending on the cell-type, but caused toxicity only at extremely high particle concentrations. Neurons did not internalize particles, while microglial cells ingested a large amount of carboxylated but almost no PEGylated NPs. PEGylation reduced the protein adsorption, toxicity and cellular uptake of NPs. After storage (shelf-life >6 months), the toxicity and cellular uptake of NPs increased. The altered biological activity of "aged" NPs was due to particle aggregation and due to the adsorption of bioactive compounds on NP surfaces. Aggregation by increasing the size and sedimentation velocity of NPs results in increased cell-targeted NP doses. The ready endotoxin adsorption which cannot be prevented by PEG coating, can render the particles toxic. The age-dependent changes in otherwise harmless NPs could be the important sources for variability in the effects of NPs, and could explain the contradictory data obtained with "identical" NPs. PMID:25673096

  15. Low surface brightness galaxies

    NASA Technical Reports Server (NTRS)

    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.

  16. Glory revealed in disk-integrated photometry of Venus

    NASA Astrophysics Data System (ADS)

    García Muñoz, A.; Pérez-Hoyos, S.; Sánchez-Lavega, A.

    2014-06-01

    Context. Reflected light from a spatially unresolved planet yields unique insight into the overall optical properties of the planet cover. Glories are optical phenomena caused by light that is backscattered within spherical droplets following a narrow distribution of sizes; they are well known on Earth as localised features above liquid clouds. Aims: Here we report the first evidence for a glory in the disk-integrated photometry of Venus and, in turn, of any planet. Methods: We used previously published phase curves of the planet that were reproduced over the full range of phase angles with model predictions based on a realistic description of the Venus atmosphere. We assumed that the optical properties of the planet as a whole can be described by a uniform and stable cloud cover, an assumption that agrees well with observational evidence. Results: We specifically show that the measured phase curves mimic the scattering properties of the Venus upper-cloud micron-sized aerosols, also at the small phase angles at which the glory occurs, and that the glory contrast is consistent with what is expected after multiple scattering of photons. In the optical, the planet appears to be brighter at phase angles of ~11-13° than at full illumination; it undergoes a maximum dimming of up to ~10% at phases in between. Conclusions: Glories might potentially indicate spherical droplets and, thus, extant liquid clouds in the atmospheres of exoplanets. A prospective detection will require exquisite photometry at the small planet-star separations of the glory phase angles. Appendices are available in electronic form at http://www.aanda.org

  17. Far-ultraviolet photometry of the globular cluster omega Cen

    NASA Technical Reports Server (NTRS)

    Whitney, Jonathan H.; O'Connell, Robert W.; Rood, Robert T.; Dorman, Ben; Landsman, Wayne B.; Cheng, K.-P.; Bohlin, Ralph C.; Hintzen, Paul M. N.; Roberts, Morton S.; Smith, Andrew M.

    1994-01-01

    We present far-ultraviolet images of the globular cluster omega Centauri obtained with the Ultraviolet Imaging Telescope (UIT) during the 1990 December Astro-1 mission. A total of 1957 sources are detected at 1620 A to a limiting ultraviolet (UV) magnitude of 16.4 in the central 24 min diameter region of the field and a limit of 15.6 over the remainder of the 40 min diameter field. Over 1400 of these sources are matched with stars on a Stroemgren u band charge coupled devices (CCD) frame obtained with the Cerro Tololo Inter-American Observatory (CTIO) 0.9 m telescope to produce a (far-UV, u) color-magnitude diagram (CMD). Completeness of the sample and error estimates are determined by photometry of artificial stars added to the images. The horizontal branch (HB) of the CMD is heavily populated hotter than 9000 K. A large number of 'extreme HB' stars are found hotter than a conspicuous break in the HB at T(sub e) approximately 16000 K. There is also a significant population of stars above the HB, the brightest of which is 4 mag brighter than the HB. Most of the hotter of these appear to be 'AGB-manque' or 'Post-Early Asymptotic Giant Branch' stars. We compare the observations to recent theoretical evolutionary tracks for the zero-age HB and subsequent phases. The tracks match the data well, with the exception of the hotter HB stars, many of which fall below the zero-age horizontal branch. It is unclear as yet whether these are a special population or an artifact of errors in the models or photometry. We identify 33 stars with T(sub e) greater than or approximately = 50000 K, which are hotter than zero-age HB stars with envelope masses of 0.003 solar mass.

  18. Recovering physical properties from narrow-band photometry

    NASA Astrophysics Data System (ADS)

    Schoenell, W.; Cid Fernandes, R.; Benítez, N.; Vale Asari, N.

    2013-05-01

    Our aim in this work is to answer, using simulated narrow-band photometry data, the following general question: What can we learn about galaxies from these new generation cosmological surveys? For instance, can we estimate stellar age and metallicity distributions? Can we separate star-forming galaxies from AGN? Can we measure emission lines, nebular abundances and extinction? With what precision? To accomplish this, we selected a sample of about 300k galaxies with good S/N from the SDSS and divided them in two groups: 200k objects and a template library of 100k. We corrected the spectra to z = 0 and converted them to filter fluxes. Using a statistical approach, we calculated a Probability Distribution Function (PDF) for each property of each object and the library. Since we have the properties of all the data from the STARLIGHT-SDSS database, we could compare them with the results obtained from summaries of the PDF (mean, median, etc). Our results shows that we retrieve the weighted average of the log of the galaxy age with a good error margin (? ? 0.1 - 0.2 dex), and similarly for the physical properties such as mass-to-light ratio, mean stellar metallicity, etc. Furthermore, our main result is that we can derive emission line intensities and ratios with similar precision. This makes this method unique in comparison to the other methods on the market to analyze photometry data and shows that, from the point of view of galaxy studies, future photometric surveys will be much more useful than anticipated.

  19. [Affective dependency].

    PubMed

    Scantamburlo, G; Pitchot, W; Ansseau, M

    2013-01-01

    Affective dependency is characterized by emotional distress (insecure attachment) and dependency to another person with a low self-esteem and reassurance need. The paper proposes a reflection on the definition of emotional dependency and the confusion caused by various denominations. Overprotective and authoritarian parenting, cultural and socio-environmental factors may contribute to the development of dependent personality. Psychological epigenetic factors, such as early socio-emotional trauma could on neuronal circuits in prefronto-limbic regions that are essential for emotional behaviour.We also focus on the interrelations between dependent personality, domestic violence and addictions. The objective for the clinician is to propose a restoration of self-esteem and therapeutic strategies focused on autonomy. PMID:23888587

  20. Some molecular/crystalline factors that affect the sensitivities of energetic materials: molecular surface electrostatic potentials, lattice free space and maximum heat of detonation per unit volume.

    PubMed

    Politzer, Peter; Murray, Jane S

    2015-02-01

    We discuss three molecular/crystalline properties that we believe to be among the factors that influence the impact/shock sensitivities of energetic materials (i.e., their vulnerabilities to unintended detonation due to impact or shock). These properties are (a) the anomalously strong positive electrostatic potentials in the central regions of their molecular surfaces, (b) the free space per molecule in their crystal lattices, and (c) their maximum heats of detonation per unit volume. Overall, sensitivity tends to become greater as these properties increase; however these are general trends, not correlations. Nitramines are exceptions in that their sensitivities show little or no variation with free space in the lattice and heat of detonation per unit volume. We outline some of the events involved in detonation initiation and show how the three properties are related to different ones of these events. PMID:25631919

  1. Uptake and bio-reactivity of polystyrene nanoparticles is affected by surface modifications, ageing and LPS adsorption: in vitro studies on neural tissue cells

    NASA Astrophysics Data System (ADS)

    Murali, Kumarasamy; Kenesei, Kata; Li, Yang; Demeter, Kornél; Környei, Zsuzsanna; Madarász, Emilia

    2015-02-01

    Because of their capacity of crossing an intact blood-brain barrier and reaching the brain through an injured barrier or via the nasal epithelium, nanoparticles have been considered as vehicles to deliver drugs and as contrast materials for brain imaging. The potential neurotoxicity of nanoparticles, however, is not fully explored. Using particles with a biologically inert polystyrene core material, we investigated the role of the chemical composition of particle surfaces in the in vitro interaction with different neural cell types. PS NPs within a size-range of 45-70 nm influenced the metabolic activity of cells depending on the cell-type, but caused toxicity only at extremely high particle concentrations. Neurons did not internalize particles, while microglial cells ingested a large amount of carboxylated but almost no PEGylated NPs. PEGylation reduced the protein adsorption, toxicity and cellular uptake of NPs. After storage (shelf-life >6 months), the toxicity and cellular uptake of NPs increased. The altered biological activity of ``aged'' NPs was due to particle aggregation and due to the adsorption of bioactive compounds on NP surfaces. Aggregation by increasing the size and sedimentation velocity of NPs results in increased cell-targeted NP doses. The ready endotoxin adsorption which cannot be prevented by PEG coating, can render the particles toxic. The age-dependent changes in otherwise harmless NPs could be the important sources for variability in the effects of NPs, and could explain the contradictory data obtained with ``identical'' NPs.Because of their capacity of crossing an intact blood-brain barrier and reaching the brain through an injured barrier or via the nasal epithelium, nanoparticles have been considered as vehicles to deliver drugs and as contrast materials for brain imaging. The potential neurotoxicity of nanoparticles, however, is not fully explored. Using particles with a biologically inert polystyrene core material, we investigated the role of the chemical composition of particle surfaces in the in vitro interaction with different neural cell types. PS NPs within a size-range of 45-70 nm influenced the metabolic activity of cells depending on the cell-type, but caused toxicity only at extremely high particle concentrations. Neurons did not internalize particles, while microglial cells ingested a large amount of carboxylated but almost no PEGylated NPs. PEGylation reduced the protein adsorption, toxicity and cellular uptake of NPs. After storage (shelf-life >6 months), the toxicity and cellular uptake of NPs increased. The altered biological activity of ``aged'' NPs was due to particle aggregation and due to the adsorption of bioactive compounds on NP surfaces. Aggregation by increasing the size and sedimentation velocity of NPs results in increased cell-targeted NP doses. The ready endotoxin adsorption which cannot be prevented by PEG coating, can render the particles toxic. The age-dependent changes in otherwise harmless NPs could be the important sources for variability in the effects of NPs, and could explain the contradictory data obtained with ``identical'' NPs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06849a

  2. Factors affecting the fate and transport of glyphosate and AMPA into surface waters of agricultural watersheds in the United States and Europe

    NASA Astrophysics Data System (ADS)

    Coupe, R.; Kalkhoff, S.; Capel, P.; Gregoire, C.

    2012-04-01

    Glyphosate [N-(phosphonomethyl)glycine] is a herbicide used extensively in almost all agricultural and urban areas of the United States and Europe. Although, glyphosate is used widely throughout the world in the production of many crops, it is predominately used in the United States on soybeans, corn, potatoes, and cotton that have been genetically modified to be tolerant to glyphosate. From 1992 to 2007, the agricultural use of glyphosate has increased from less than 10,000 Mg to more than 80,000 Mg, respectively. The greatest areal use is in the midwestern United States where glyphosate is applied on transgenic corn and soybeans. Because of the difficulty and expense in analyzing for glyphosate and AMPA (aminomethylphosphonic acid, a primary glyphosate degradate) in water, there have been only small scale studies on the fate and transport of glyphosate. The characterization of the transport of glyphosate and AMPA on a watershed scale is lacking. Glyphosate and AMPA were frequently detected in the surface waters of 4 agricultural watersheds in studies conducted by the U.S. Geological Survey in the United States and at the Laboratory of Hydrology and Geochemistry of Strasbourg. Two of these basins were located in the midwestern United States where the major crops are corn and soybean, the third is located the lower Mississippi River Basin where the major crops are soybean, corn, rice, and cotton, and the fourth was located near Strasbourg, France where the use of glyphosate was on a vineyard. The load as a percent of use ranged from 0.009 to 0.86 percent and could be related to 3 factors: source strength, hydrology, and flowpath. Glyphosate use in a watershed results in some occurrence in surface water at the part per billion level; however, those watersheds most at risk for the offsite transport of glyphosate are those with high application rates, rainfall that results in overland runoff, and a flowpath that does not include transport through the soil.

  3. EXTENDED PHOTOMETRY FOR THE DEEP2 GALAXY REDSHIFT SURVEY: A TESTBED FOR PHOTOMETRIC REDSHIFT EXPERIMENTS

    SciTech Connect

    Matthews, Daniel J.; Newman, Jeffrey A. [Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260 (United States); Coil, Alison L. [Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States); Cooper, Michael C. [Center for Galaxy Evolution, Department of Physics and Astronomy, University of California, Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Gwyn, Stephen D. J., E-mail: djm70@pitt.edu, E-mail: janewman@pitt.edu, E-mail: acoil@ucsd.edu, E-mail: m.cooper@uci.edu, E-mail: Stephen.Gwyn@nrc-cnrc.gc.ca [Canadian Astronomical Data Centre, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia V9E 2E7 (Canada)

    2013-02-15

    This paper describes a new catalog that supplements the existing DEEP2 Galaxy Redshift Survey photometric and spectroscopic catalogs with ugriz photometry from two other surveys: the Canada-France-Hawaii Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs. We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to provide a more uniform data set. We have also used this improved photometry to predict DEEP2 BRI photometry in regions where only poorer measurements were available previously. In addition, we have included improved astrometry tied to SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog contains {approx}27, 000 objects with full ugriz photometry as well as robust spectroscopic redshift measurements, 64% of which have r > 23. By combining the secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz photometry, we have created a catalog that can be used as an excellent testbed for future photo-z studies, including tests of algorithms for surveys such as LSST and DES.

  4. Are ciliated protozoa communities affected by macrophyte species, date of sampling and location in horizontal sub-surface flow constructed wetlands?

    PubMed

    Puigagut, Jaume; Maltais-Landry, Gabriel; Gagnon, Vincent; Brisson, Jacques

    2012-06-01

    The effects of design and operational factors on the dynamics of ciliated protozoa in constructed wetlands (CWs) treating wastewater remain poorly known, although bacterivory by ciliates could have important implications for nutrient cycling in these systems. We conducted a greenhouse experiment with eight wetland mesocosms (1 m(2)) fed with synthetic wastewater to assess how macrophyte species (Phragmites australis, Phalaris arundinacea, and Typha angustifolia), location within CW (longitudinal, depth), and temporal fluctuations affect ciliate abundance and diversity. Urosoma similis was the most abundant taxon, but Hypotrichidae, Scuticociliates, Drepomonas revoluta, and Acineria uncinata were also abundant. Longitudinal location had the highest impact on ciliate dynamics, with more abundant and diverse communities in the initial section of wetlands. P. australis/T. angustifolia and P. arundinacea had the most and least favorable conditions for ciliates, respectively, but differences among macrophytes were mostly not significant. Ciliate abundance appeared to decline from August to November, most likely because of lower temperature and plant inputs of organic matter and oxygen. Depth had no apparent impact on ciliate dynamics, suggesting that sampling at multiple depths in CW is not necessary to adequately monitor ciliate communities. Overall, our results suggest that macrophytes, location, and date of sampling influenced ciliated dynamics but stress the need for direct manipulative experiments of ciliate abundance, diversity, and composition conducted on a full annual cycle to better understand the impact of ciliates on nutrient cycling in CWs. This is especially true to determine if the associations found in our principal component analysis are robust. PMID:22483709

  5. The Araucaria Project. A Distance Determination to the Local Group Spiral M33 from Near-Infrared Photometry of Cepheid Variables

    E-print Network

    Gieren, W; Pietrzynski, G; Konorski, P; Suchomska, K; Graczyk, D; Pilecki, B; Bresolin, F; Kudritzki, R P; Karczmarek, P; Gallenne, A; Calderon, P; Geisler, D

    2013-01-01

    Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, we have obtained deep near-infrared photometry for 26 long-period Cepheids in this galaxy with the ESO VLT. From the data we constructed period-luminosity relations in the J and K bands which together with previous optical VI photometry for the Cepheids by Macri et al. were used to determine the true distance modulus of M33, and the mean reddening affecting the Cepheid sample with the multiwavelength fit method developed in the Araucaria Project. We find a true distance modulus of 24.62 for M33, with a total uncertainty of +- 0.07 mag which is dominated by the uncertainty on the photometric zero points in our photometry. The reddening is determined as E(B-V)=0.19 +- 0.02, in agreement with the value used by the HST Key Project of Freedman et al. but in some discrepancy with other recent determinations based on blue supergiant spectroscopy and an O-type eclipsing binary which yielded lower reddening values. Our der...

  6. THE ARAUCARIA PROJECT. A DISTANCE DETERMINATION TO THE LOCAL GROUP SPIRAL M33 FROM NEAR-INFRARED PHOTOMETRY OF CEPHEID VARIABLES

    SciTech Connect

    Gieren, Wolfgang; Pietrzynski, Grzegorz; Graczyk, Dariusz, E-mail: wgieren@astro-udec.cl, E-mail: pietrzyn@hubble.cfm.udec.cl [Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warsaw (Poland); and others

    2013-08-10

    Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, we have obtained deep near-infrared photometry for 26 long-period Cepheids in this galaxy with the ESO Very Large Telescope. From the data, we constructed period-luminosity relations in the J and K bands which together with previous optical VI photometry for the Cepheids by Macri et al. were used to determine the true distance modulus of M33, and the mean reddening affecting the Cepheid sample with the multiwavelength fit method developed in the Araucaria Project. We find a true distance modulus of 24.62 for M33, with a total uncertainty of {+-}0.07 mag which is dominated by the uncertainty on the photometric zero points in our photometry. The reddening is determined as E(B - V) = 0.19 {+-} 0.02, in agreement with the value used by the Hubble Space Telescope Key Project of Freedman et al. but in some discrepancy with other recent determinations based on blue supergiant spectroscopy and an O-type eclipsing binary which yielded lower reddening values. Our derived M33 distance modulus is extremely insensitive to the adopted reddening law. We show that the possible effects of metallicity and crowding on our present distance determination are both at the 1%-2% level and therefore minor contributors to the total uncertainty of our distance result for M33.

  7. Binary-induced magnetic activity? Time-series echelle spectroscopy and photometry of HD123351 = CZ CVn

    E-print Network

    Strassmeier, K G; Weber, M; Granzer, T; Bartus, J; Olah, K; Rice, J B

    2011-01-01

    We present a first and detailed study of the bright and active K0IV-III star HD 123351. The star is found to be a single-lined spectroscopic binary with a period of 147.8919+-0.0003 days and a large eccentricity of e=0.8086+-0.0001. The rms of the orbital solution is just 47 m/s, making it the most precise orbit ever obtained for an active binary system. The rotation period is constrained from long-term photometry to be 58.32+-0.01 days. It shows that HD 123351 is a very asynchronous rotator, rotating five times slower than the expected pseudo-synchronous value. Two spotted regions persisted throughout the 12 years of our observations. Four years of Halpha, CaII H&K and HeI D3 monitoring identifies the same main periodicity as the photometry but dynamic spectra also indicate that there is an intermittent dependence on the orbital period, in particular for Ca ii H&K in 2008. Line-profile inversions of a pair of Zeeman sensitive/insensitive iron lines yield an average surface magnetic-flux density of 54...

  8. Near-field photometry for organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Li, Rui; Harikumar, Krishnan; Isphording, Alexandar; Venkataramanan, Venkat

    2013-03-01

    Organic Light Emitting Diode (OLED) technology is rapidly maturing to be ready for next generation of light source for general lighting. The current standard test methods for solid state lighting have evolved for semiconductor sources, with point-like emission characteristics. However, OLED devices are extended surface emitters, where spatial uniformity and angular variation of brightness and colour are important. This necessitates advanced test methods to obtain meaningful data for fundamental understanding, lighting product development and deployment. In this work, a near field imaging goniophotometer was used to characterize lighting-class white OLED devices, where luminance and colour information of the pixels on the light sources were measured at a near field distance for various angles. Analysis was performed to obtain angle dependent luminous intensity, CIE chromaticity coordinates and correlated colour temperature (CCT) in the far field. Furthermore, a complete ray set with chromaticity information was generated, so that illuminance at any distance and angle from the light source can be determined. The generated ray set is needed for optical modeling and design of OLED luminaires. Our results show that luminance non-uniformity could potentially affect the luminaire aesthetics and CCT can vary with angle by more than 2000K. This leads to the same source being perceived as warm or cool depending on the viewing angle. As OLEDs are becoming commercially available, this could be a major challenge for lighting designers. Near field measurement can provide detailed specifications and quantitative comparison between OLED products for performance improvement.

  9. The rotation period of Epsilon Eri from photometry of its starspots

    NASA Technical Reports Server (NTRS)

    Frey, Gary J.; Hall, Douglas S.; Mattingly, Phil; Robb, Steve; Wood, Jim; Zeigler, Kenneth; Grim, Bruce

    1991-01-01

    BV photometry at six observatories in 1988/1989 and 1989/1990 shows variability resulting from five starspots which lived 1 or 2 months each, had rotation periods in the range P between 10.0d and 12.3d, and had amplitudes in the range 0.01 m - 0.03 m. From the range in P it was possible to estimate k greater than 0.20 +/- 0.05 for the differential rotation coefficient. Ca II K-line photometry, polarimetry, and earlier photometry reported in the literature has also shown variability with periodicities in the same 10 d -12 d range.

  10. Optical Photometry of BY Cam Modeled Using a Multipolar Magnetic Field Structure

    NASA Astrophysics Data System (ADS)

    Morales, John; Mason, P. A.; Zhilkin, A.; Bisikalo, D. V.; Robinson, E. L.

    2014-01-01

    We present new high-speed broad-band optical photometry of the asynchronous polar (magnetic cataclysmic variable) BY Cam. Observations were obtained at the 2.1-m Otto Struve Telescope of McDonald observatory with 3s integration times. In an attempt to understand the complex changes in accretion flow geometry, we performed full 3D MHD simulations assuming a variety of white dwarf magnetic field structures including both aligned and non-aligned dipole plus quadrupole field components. We compare model predictions with photometry and various phases of the beat cycle and find that synthetic light curves derived from a multipolar field structure are consistent with the optical photometry.

  11. Factors affecting dissolved phosphorus and nitrate concentrations in ground and surface water for a valley dairy farm in the northeastern United States.

    PubMed

    Flores-López, Francisco; Easton, Zachary M; Geohring, Larry D; Steenhuis, Tammo S

    2011-02-01

    Agriculture often is considered to be a contributor of soluble reactive phosphorus (SRP) and nitrate-N (NO3- -N) to surface waters. This research analyzed SRP and NO3- -N concentrations in groundwater and in a creek fed by groundwater on a valley dairy farm in the Cannonsville basin of the New York City (NYC) watershed. A total of 37 groundwater piezometers were installed to depths of 0.3 to 1.5 m. Water-table depth and concentrations of SRP, NO3- -N, dissolved organic carbon (DOC), and dissolved oxygen were measured at regular intervals over a three-year period. A multivariate mixed model analysis of variance indicated that the SRP and NO3- -N concentrations were controlled primarily by three classes of variables: environmental variables, including precipitation and water table depth; source variables, including manure applied and crop type; and chemical variables, including DOC and dissolved oxygen concentrations in groundwater. The highest groundwater concentrations of N03- -N and SRP were found at the shallowest water-table depths, which has implications for agricultural nutrient management in areas with shallow groundwater. PMID:21449473

  12. Response surface methodology for optimization of culture conditions for dye decolorization by a fungus, Aspergillus niger HM11 isolated from dye affected soil

    PubMed Central

    Karthikeyan, K; Nanthakumar, K; Shanthi, K; Lakshmanaperumalsamy, P

    2010-01-01

    Background and Objectives Discharge of wastewater from textile dyeing industries has been a problem in terms of pollution and treatment of these waters is a great task. Keeping this in mind, the aim of our current research is to study the effect of various bioprocess variables on decolorization of an azo dye, Congo red, by a fungal isolate, Aspergillus niger HM11. Materials and Methods Central composite design (CCD) and response surface methodology (RSM) have been applied to design experiments to evaluate the interactive effects of the operating variables: on the decolorization of Congo red. A total of 30 experiments were conducted in the present study and a regression coefficient between the variables was generated. Results The RSM indicated that pH 6.0, 150 rpm agitation, incubation time of 36 hrs and a glucose concentration of 1.0% were optimal for maximum decolorization of Congo red and the response indicated excellent evaluation of experimental data. Conclusion From this study, it is very obvious that the fungal isolate, Aspergillus niger HM11 can be used as a promising microbial strain for decolorization of textile dyeing effluent containing similar dyes. PMID:22347575

  13. A study of lubrication, processing conditions, and material combinations that affect the wear of micro-textured-carbide coated cobalt-chromium-molybdenum alloy surfaces used for artificial joints implants

    NASA Astrophysics Data System (ADS)

    Ettienne-Modeste, Geriel A.

    Total joint replacement remains one of the most successful treatments for arthritis. The most common materials used for artificial joints are metals (e.g., cobalt-chrome alloys or titanium alloys), which articulate against ultra-high molecular weight polyethylene. Wear related failures of artificial joints may be reduced with the use of novel micro-textured carbide surfaces. The micro-textured carbide surfaces were deposited on a CoCrMo alloy using microwave plasma-assisted chemical vapor deposition. Wear tests were conducted to determine wear mechanisms and properties of the micro-textured surfaces. The research presented in this thesis addresses: (1) rheolgoical behavior of bovine calf serum with and without antibacterial agents to determine whether they can be used as appropriate models for synovial fluid, (2) the wear behavior of the micro-textured CoCrMo surface system, and (3) the mechanical and material properties of the micro-textured CoCrMo alloy surface relevant to wear performance. The rheological studies showed that the apparent viscosity of bovine calf serum increased with an increase in concentration before and after the serum was used for wear testing. The wear analysis showed that the processing conditions (2hr deposition vs. 4hr deposition times) affected the wear properties. The 2hr carbide-on-carbide lubricated in 50% BCS produced the lowest wear factor and rate for the five wear couple systems containing the carbide disk or plate material. Greater wear was produced in serum without penicillin/streptomycin (P/S) compared to the serum containing P/S. A greater carbide coating thickness 10 (micrometers) was produced during the 4hr deposition time than for the 2hr deposition (˜3mum). The nano-hardness value was higher than the micro-hardness for both the 4hr and 2hr carbide surfaces. The micro-hardness results of the worn carbide surfaces showed that an increase in BCS concentration from 0% to 100% increased the micro-hardness (HV) for carbide surfaces (from 873 to 1344 HV).

  14. We triggered a multi-wavelength observing campaign including radio observations at RATAN-600, millimeter observations at Plateau de Bure, optical photometry at sev-

    E-print Network

    Cai, Long

    , millimeter observations at Plateau de Bure, optical photometry at sev- eral ground-based observatories, near of the catalogue. 1.2 Photometry Optical photometry is based on the detections derived from SExtractor32 , using isopho- tal corrected photometry and Midas/DAOPHOT33 . The photometric calibration against the reference

  15. The Structure of Rapidly Rotating Late-Type Spiral Galaxies: I. Photometry, HI and Optical Kinematics

    E-print Network

    K. Spekkens; R. Giovanelli

    2006-07-25

    We present I-band photometry, long-slit optical spectroscopy, and new aperture synthesis HI observations for eight late-type spirals with rotation velocities in the range 243 km/s galaxy population; here we discuss the basic properties of these ``fast rotators'', and derive hybrid optical/HI rotation curves for each. Despite the presence of HI warps and low-mass companions in many systems, their kinematics are regular and there is excellent agreement between optical and HI tracers near the optical radius r_{opt}. At high inclinations at which projection effects are negligible, the sample galaxies exhibit flat, featureless rotation curves out to their last measured points at 1.7r_{opt}--3.5 r_{opt}. The intermediate inclination systems are also consistent with a constant rotation amplitude for r > 0.5 r_{opt}. We therefore find no evidence for declining rotation curves at the high-mass end of the late-type spiral galaxy population. Combining our data with the compilation of spirals with reliable outer HI kinematics from the work of Casertano & van Gorkom, we find no convincing trends between logarithmic outer rotation curve slopes and rotation amplitudes or surface brightnesses for galaxies with V_{rot} > 220 km/s. Correlations between these slopes and morphological types or disk scale lengths are also marginal in this regime.

  16. Isolated ellipticals and their globular cluster systems. I. Washington photometry of NGC 3585 and NGC 5812

    NASA Astrophysics Data System (ADS)

    Lane, R. R.; Salinas, R.; Richtler, T.

    2013-01-01

    The globular cluster (GC) systems of isolated elliptical galaxies have only recently begun to be studied in detail, and may exhibit morphological connections to the evolutionary histories of their hosts. Here we present the first in a series of wide-field analyses of the GC systems of the isolated ellipticals - Washington C and R photometry of NGC 3585 and NGC 5812 down to R ~ 24 mag. The GC systems are characterised, with each system displaying both the "Universal" blue peak at (C - R) ~ 1.3, and a red peak, but each with differing strengths. The total number of GCs in each system, and their specific frequencies, are estimated. The GC colours and specific frequencies are highly indicative that the host galaxy environment plays a role in shaping its GC system. We produce, and subtract, accurate models of each galaxy, revealing interesting underlying features, including the first definitive evidence that NGC 5812 is interacting with a dwarf companion galaxy. From the galaxy models we also determine surface brightness and colour profiles. Both colour profiles appear quite flat and with (C - R) ~ 1.7 and we discuss the apparent youth of NGC 3585 in the context of this work. Figures 6, 7 and Appendix A are available in electronic form at http://www.aanda.org

  17. SOAP: A Tool for the Fast Computation of Photometry and Radial Velocity Induced by Stellar Spots

    NASA Astrophysics Data System (ADS)

    Boisse, I.; Bonfils, X.; Santos, N. C.; Figueira, P.

    2013-04-01

    Dark spots and bright plages are present on the surface of dwarf stars from spectral types F to M, even in their low-active phase (like the Sun). Their appearance and disappearance on the stellar photosphere, combined with the stellar rotation, may lead to errors and uncertainties in the characterization of planets both in radial velocity (RV) and photometry. Spot Oscillation and Planet (SOAP) is a tool offered to the community that enables to simulate spots and plages on rotating stars and computes their impact on RV and photometric measurements. This tool will help to understand the challenges related to the knowledge of stellar activity for the next decade: detect telluric planets in the habitable zone of their stars (from G to M dwarfs), understand the activity in the low-mass end of M dwarf (on which future projects, like SPIRou or CARMENES, will focus), limitation to the characterization of the exoplanetary atmosphere (from the ground or with Spitzer, JWST), search for planets around young stars. These can be simulated with SOAP in order to search for indices and corrections to the effect of activity.

  18. DDO Photometry of M71: Carbon and Nitrogen Patterns Among Evolving Giants

    E-print Network

    M. M. Briley; G. H. Smith; C. F. Claver

    2001-08-07

    We present V, B-V, and DDO C(41-42) and C(42-45) photometry for a sample of 75 red giants down to M_V = +2 in the relatively metal-rich Galactic globular cluster M71. The C(41-42) colors reveal a bimodal distribution of CN band strengths generally anticorrelated with CH band strength as measured by the C(42-45) color. Both DDO colors agree well with those found in 47 Tucanae -- a nearby globular cluster of similar metallicity -- and suggest nearly identical C and N abundance patterns among the giants of both clusters. A comparison with synthetic DDO colors demonstrates that little change in surface C or N abundance is required to match the colors of the M71 giants over the entire luminosity range observed. Apparently like 47 Tuc (a cluster of much greater mass and central concentration), M71 exhibits an abundance pattern which cannot be solely the result of internal mixing.

  19. Infrared photometry and polarimetry of Cygnus X-3

    NASA Technical Reports Server (NTRS)

    Jones, Terry Jay; Gehrz, Robert D.; Kobulnicky, Henry A.; Molnar, Lawrence A.; Howard, Eric M.

    1994-01-01

    We present photometry and linear polarimetry of Cygnus X-3 at K (2.2 micrometers) obtained over a 5 yr period. Photometry and polarimetry at J, H, and K of nearby field stars is also presented. From an analysis of these data we find: (1) Using the x-ray ephemeris of Kitamoto et al. (ApJ, 384, 263 (1992), including the first and second derivatives of the period, the leading edge of the decline to minimum in the quiescent K light curve has not changed in phase since 1974. The duration of the minimum in the light curve has changed significantly between different epochs, becoming much broader in 1993 than it was previously. (2) In addition to an interstellar polarization component, it is likely Cyg X-3 has an intrinsic polarization component that is variable. The variations in the polarization do not show any diagnostic pattern with orbital phase. A crude analysis of the polarization suggests the intrinsic polarization of Cyg X-3 has a mean position angle of approximately 12 deg, nearly the same as the direction of the expanding radio lobes. This is consistent with circumstellar electrons scattering in an equatorial disk that is perpendicular to the lobe axis. (3) The mean position angle for the interstellar polarization in the direction of Cyg X-3 is 150 deg. This is nearly perpendicular to the axis of interstellar radio scattering seen in the extended (Very Long Baseline Inteferometry (VLBI) images. Since the position angle of interstellar polarization is the same as the projected magnetic field direction, this suggests the interstellar (not circumstellar) scattering must be taking place perpendicular to the interstellar magnetic field lines. (4) Cyg X-3 was observed at K during a flare on 1992 September 30 with a temporal resolution of 6 s. The flaring had rise and fall times of approximately 50 s with peak intensities up to 80 mJy. The flux between individual flare events never dropped to quiescent levels for the duration of our observations (approximately 2000 s).

  20. Photometry and Spectroscopy of BD+35 1111 in M38

    NASA Astrophysics Data System (ADS)

    Souza, Steven P.; Kwitter, Karen B.; Sami, Mona; Beltz-Mohrmann, Gillian

    2014-06-01

    BD+35 1111 is a ~10.5-magnitude star in the field of M38, an open cluster that has been a target of our ongoing study of H? emission variability in massive stars via narrowband CCD photometry (e.g. Souza, Davis, and Teich 2013, BAAS. 45, PM354.22). BD+35 1111 has no MKK classification in the literature, and is not listed as variable in GCVS, VSX, or NSVS. It is included, with no further characterization, in both the Vatican and Kohoutek catalogs of emission line stars. Using inhomogeneous ensemble photometry (e.g. Bhatti, Richmond, Ford, and Petro 2010, ApJ Supp., 186, 233), we find it to be an irregular variable with a range of ~0.15 mag. To further understand this star we obtained a medium-resolution spectrum using the DIS spectrograph on the ARC 3.5-meter telescope at Apache Point Observatory. We classify BD+35 1111 as B2Ve, the only confirmed Be star in the field of M38. This raises the question of membership, since the age of M38 is likely 250 Ma or greater (Pandey et al. 2007, Publ. Astron. Soc. Japan 59, 547). From published B and V magnitudes we find a nominal distance to BD+35 1111 of 1.6 kpc, but with a range of 1.3 to 2.0 kpc, marginally consistent with distance estimates for M38 ranging from 1.0 to 1.4 kpc. If a member, BD+35 1111 is a candidate blue straggler. If not, it may have escaped from a nearby younger cluster, possibly Kronberger 1 (Kronberger et al. 2006, A&A 447, 921), which has the right heliocentric distance and age. The notion that BD+35 1111 is behind M38 is supported by its reddening of EB-V ~ 0.5, significantly higher than for M38 itself 0.24). We gratefully acknowledge support for student research from NSF grant AST-1005024 to the Keck Northeast Astronomy Consortium, Williams College, and NASA via an American Astronomical Society Small Research Grant.

  1. Photometry of Be Stars in the vicinity of COROT primary targets for asteroseismology

    E-print Network

    J. Gutierrez-Soto; J. Fabregat; J. Suso; A. M. Hubert; M. Floquet; R. Garrido

    2003-09-29

    We present differential photometry of Be stars close to potential COROT primary targets for asteroseismology. Several stars are found to be short period variables. We propose them to be considered as secondary targets in the COROT asteroseismology fields.

  2. Spectroscopy and photometry of the nova M31N 2015-01a

    NASA Astrophysics Data System (ADS)

    Fabrika, S.; Barsukova, E. A.; Valeev, A. F.; Vinokurov, A.; Sholukhova, O.; Goranskij, V. P.; Hornoch, K.; Henze, M.; Shafter, A. W.

    2015-01-01

    We report optical spectroscopy and photometry of the recent M31 nova M31N 2015-01a first detected by MASTER (ATel #6911) and also observed spectrally (ATels #6924, #6941, #6952) and photometrically (MASTER, ATel #6951).

  3. VizieR Online Data Catalog: WASP-104b and WASP-106b photometry (Smith+, 2014)

    NASA Astrophysics Data System (ADS)

    Smith, A. M. S.; Anderson, D. R.; Armstrong, D. J.; Barros, S. C. C.; Bonomo, A. S.; Bouchy, F.; Brown, D. J. A.; Collier, Cameron A.; Delrez, L.; Faedi, F.; Gillon, M.; Gomez Maqueo Chew, Y.; Hebrard, G.; Jehin, E.; Lendl, M.; Louden, T. M.; Maxted, P. F. L.; Montagnier, G.; Neveu-Vanmalle, M.; Osborn, H. P.; Pepe, F.; Pollacco, D.; Queloz, D.; Rostron, J. W.; Segransan, D.; Smalley, B.; Triaud, A. H. M. J.; Turner, O. D.; Udry, S.; Walker, S. R.; West, R. G.; Wheatley, P. J.

    2014-09-01

    The stars WASP-104 and WASP-106 were observed by SuperWASP-N from 2008 to 2011, and by WASP-South from 2009 to 2010. This differential survey photometry has been de-reddened and normalised. Further photometry was obtained using the TRAPPIST, Euler, Liverpool and Isaac Newton telescopes in 2013 and 2014. All these data are plotted in Figures 1 and 2. (1 data file).

  4. VizieR Online Data Catalog: UBVRI photometry in NGC6791 (Brogaard+, 2012)

    NASA Astrophysics Data System (ADS)

    Brogaard, K.; Vandenberg, D. A.; Bruntt, H.; Grundahl, F.; Frandsen, S.; Bedin, L. R.; Milone, A. P.; Dotter, A.; Feiden, G. A.; Stetson, P. B.; Sandquist, E.; Miglio, A.; Stello, D.; Jessen-Hansen, J.

    2012-06-01

    New reduction of photometric B, V, I observations from Stetson et al. (2003, Cat. J/PASP/115/413) with updated photometry zero-points according to Stetson et al. (2005PASP..117..563S), and the same photometry, but empirically corrected for differential reddening using the procedure described in Milone et al. (2012A&A...540A..16M). (1 data file).

  5. Southern Milky Way carbon stars - New candidates, JHK photometry, and radial velocities

    SciTech Connect

    Blanco, V.M.; Cook, K.H.; Schechter, P.L.; Aaronson, M. (Observatorio Interamericano de Cerro Tololo, La Serena (Chile); Steward Observatory, Tucson, AZ (USA); Mount Wilson and Las Campanas Observatories, Pasadena, CA (USA))

    1989-07-01

    Data are presented for low-latitude southern Milky Way carbon stars. Coordinates and cross identifications are given for carbon stars (67 of which are confirmed new discoveries) in seven fields deemed to be unusually transparent. JHK photometry is presented for 520 stars. Velocities are presented for 393 stars. Improved coordinates are presented for selected stars in Westerlund's catalog. Averaged photometry and velocities are presented for a sample of 336 stars. 26 refs.

  6. Worldwide photometry of the January 1989 Tau Persei eclipse

    NASA Technical Reports Server (NTRS)

    Hall, Douglas S.; Curott, David R.; Barksdale, William S.; Diethelm-Sutter, Roger; Ells, Jack

    1991-01-01

    New UBV photoelectric photometry of Tau Persei obtained at 19 different observatories during its recent January 1989 eclipse is presented. Mideclipse occurred at JD 2 447 542.31 + or - 0.01. The resulting light curve, though not complete at all phases, is solved for the elements with the help of two quantities derived from spectroscopy: the eclipse is 84 percent total at mideclipse, and the ratio of the radii is 0.135 + or - 0.01. Radii relative to the semimajor axis are 0.0236 for the G5 giant and 0.0032 for the A2 star. With a reasonable total mass assumed, the absolute radii say the A2 star could be luminosity class V or somewhat evolved and the G5 star is between III and II but could be closer to II. The G5 giant is brighter than the A2 star by 1.72 mag in V and the color excess in B - V is 0.06 mag, both quantities consistent (within uncertainties) with earlier estimates of Ake (1986). The eclipse duration, from first to fourth contact, is 2.09 day. The orbital inclination is 88.74 deg, consistent with what McAlister derived from speckle interferometry. Because of the large (e = 0.73) eccentricity, there is no secondary eclipse at all.

  7. Infrared photometry of z~1 3C quasars

    E-print Network

    Chris Simpson; Steve Rawlings

    2000-05-30

    We present JHKL' photometry of a complete sample of steep-spectrum radio-loud quasars from the revised 3CR catalogue in the redshift range 0.65 < z < 1.20. After correcting for contributions from emission lines and the host galaxies, we investigate their spectral energy distributions (SEDs) around 1 micron. About 75% of the quasars are tightly grouped in the plane of optical spectral index, alpha_lo, versus near-infrared spectral index, alpha_hi, with the median value of alpha_lo close to the canonical value, and the median alpha_hi slightly flatter. We conclude that the fraction of moderately-obscured, red quasars decreases with increasing radio power, in accordance with the `receding torus' model which can also explain the relatively flat median near-infrared spectra of the 3CR quasars. Two of the red quasars have inverted infrared spectral indices, and we suggest that their unusual SEDs might result from a combination of dust-scattered and transmitted quasar light.

  8. GASPS Photometry of the Tucana-Horologium Association

    NASA Technical Reports Server (NTRS)

    Roberge, Donaldson J.; Roberge, Aki

    2010-01-01

    The GASPS Open Time Key Programme on Herschel represents a new opportunity to sensitively probe protoplanetary and debris disks at far-IR wavelengths. We present preliminary PACS 70 and 160 micron photometry of eighteen stars in the 30 Myr-old Tucana-Horologium association. Of these eighteen, eight were detected in the 70 micron band. Four of these eight were also detected in the 160 micron band. We constructed SEDs for these systems using optical data from Hipparcos (B and V), near-IR data from 2MASS (J, H, and K), mid-IR data from IRAS and Spitzer MIPS (12 and 24 microns, respectively), and the new far-IR data from PACS. For the stars showing IR excess emission, we fit simple single-temperature blackbody curves to the IR excess in order to determine the rough dust abundances and temperatures. Dust observations at these wavelengths will also be important for comparison with upcoming Herschel PACS spectra that will search for gas in the disks. Our goal is to determine or limit the ever-allusive gas-to-dust ratio for these disk systems.

  9. Glory revealed in disk-integrated photometry of Venus

    E-print Network

    Muñoz, A García; Sánchez-Lavega, A

    2014-01-01

    Context. Reflected light from a spatially unresolved planet yields unique insight into the overall optical properties of the planet cover. Glories are optical phenomena caused by light that is backscattered within spherical droplets following a narrow distribution of sizes; they are well known on Earth as localised features above liquid clouds. Aims. Here we report the first evidence for a glory in the disk-integrated photometry of Venus and, in turn, of any planet. Methods. We used previously published phase curves of the planet that were reproduced over the full range of phase angles with model predictions based on a realistic description of the Venus atmosphere. We assumed that the optical properties of the planet as a whole can be described by a uniform and stable cloud cover, an assumption that agrees well with observational evidence. Results. We specifically show that the measured phase curves mimic the scattering properties of the Venus upper-cloud micron-sized aerosols, also at the small phase angles ...

  10. Small Telescope Infrared Photometry of the epsilon Aurigae Eclipse

    NASA Astrophysics Data System (ADS)

    Rutherford, T. P.

    2012-06-01

    Near-infrared photometry of epsilon Aurigae, in the H- and J-bands, was undertaken during the 2009-2011 eclipse using telescopes of moderate size (8-inch and 14-inch diameter). Instruments of this size successfully collected scientific data in the H- and J-bands. Observations were made from the campus of East Tennessee State University (ETSU), Johnson City, Tennessee, the campus of King College, Bristol, Tennessee, and from the author's home. Signal/Noise ratios of approximately 45 were obtained during times of maximum eclipse. Higher S/N ratios could have been obtained by extending the length of time on target. S/N ratios of almost 100 were obtained outside of eclipse. The infrared light curves produced closely parallel the light curve in the visual range (V), being about 0.5 magnitude brighter in H and 0.7 magnitude brighter in J. The eclipse was easily detected and followed throughout its duration. The rate of ingress was shallower than the rate of egress in both the H- and J-bands. The background variations of the primary star were readily detected.

  11. CCD Photometry of the W UMa type star QX Andromeda

    NASA Astrophysics Data System (ADS)

    Ren, A. B.; Zhang, X. B.; Luo, C. Q.; Luo, Y. P.; Deng, L. C.; Luo, Z. Q.

    2011-04-01

    We present new B- and V-band photometry of the W UMa-type binary system QX And, which is a member of the open cluster NGC 752. Revised orbital period and new ephemerides were given for the binary system based on the data of times of light minima. The result of a period analysis reveals that the system is undergoing a continuous orbital period increase during the past decades. The rate of period increasing turns out to be about 2.7 × 10 -7 d yr -1. With the Wilson-Devinney code, a photometric solution is computed. It yields a contact configuration for the system with a filling factor of 0.361. Combining the results from the photometric solution along with that from the radial-velocity observations, we have determined the absolute parameters for the two components of the system. The masses, radii and luminosity of the primary and secondary stars are calculated as 1.43 ± 0.04 M?, 1.45 ± 0.09 R?, 2.87 ± 0.40 L? and 0.44 ± 0.02 M?, 0.87 ± 0.05 R?, 0.99 ± 0.13 L?, respectively. The evolutionary status and physical nature of the contact binary system were discussed compared with the theoretical models.

  12. Color-magnitude diagram of Palomar 4 - CCD photometry

    NASA Astrophysics Data System (ADS)

    Christian, C. A.; Heasley, J. N.

    1986-04-01

    Photometry of the globular cluster Pal 4 was obtained with the RCA CCD camera on the 3.6 m Canada-France-Hawaii Telescope on Mauna Kea. The color-magnitude diagram of the cluster shows a well-defined red horizontal branch, typical of outer halo systems, and an asymptotic giant branch well separated from the giant branch. The population of Pal 4 has been sampled to the main-sequence turnoff region (V = 25), allowing a detailed comparison of this distant object with theoretical models. The cluster parameters consistent with the CCD data are (m - M)0 = 20.1 + or - 0.1 mag, E(B - V) = 0.02 + or - 0.02, and Fe/H forbidden line = -1.7 + or - 0.1 with Y =0.2. The age of the cluster, determined by comparison with the isochrones of VandenBerg and Bell (1985) is consistent with an age of 15 + or - 1 Gyr, similar to inner halo globular clusters with ages determined in the same way.

  13. The CCD photometry of the globular cluster Palomar 1.

    NASA Astrophysics Data System (ADS)

    Borissova, J.; Spassova, N.

    1995-04-01

    A CCD photometry of the halo cluster Palomar 1 is presented in the Thuan-Gunn photometric system. The principal sequences of the color-magnitude diagrams are delineated in different spectral bands. The color-magnitude diagrams of the cluster show a well defined red horizontal branch, a subgiant branch and a main-sequence down to about two magnitudes below the main sequence turnoff. The giant branch is absent and the brightest stars are the horizontal branch stars. The age of the cluster determined by comparison with the isochrones of Bell & Vanden Berg (1987) is consistent with an age in the interval 12-14Gyr. A distance modulus of (m-M)_g0_=15.38+/-0.15 magnitude and E(g-r)=0.16 has been derived. An estimate of the cluster structural parameters such as core radius and concentration parameter gives r_c_=1.5pc and c=1.46. A mass estimate of 1.1 10^3^Msun_ and a mass-to-light ratio of 1.79 have been obtained using King's (1966) method. The morphology of color-magnitude diagrams allows Pal 1 to be interpreted as probably a globular cluster rather than an old open one.

  14. Stroemgren photometry of globular clusters: M55 & M22

    E-print Network

    P. Richter; M. Hilker; T. Richtler

    1999-07-15

    We present Stroemgren CCD photometry for the two galactic globular clusters M55 (NGC 6809) and M22 (NGC 6656). We find average Stroemgren metallicities of -1.71 dex for M55 and -1.62 dex for M22. The determination of metal abundances in cluster giants with the Stroemgren m1 index in comparison with spectroscopic data from Briley et al. (1993) and Norris & Freeman (1982, 1983) shows that M55 and M22 have different distributions of cyanogen strengths. In M55, no CN abundance variations are visible among the giant-branch stars. In striking contrast, a large dispersion of cyanogen strengths is seen in M22. For M22 we find patchily distributed variations in the foreground reddening of E(B-V)=0.07, which explain the colour dispersion among the giant-branch stars. There is no evidence for a spread in iron within M22 since the variations in m1 are dominated by the large range in CN abundances, as already found by Anthony-Twarog et al. (1995). The difference between M55 and M22 may resemble the difference in integral CN band strength between M31 globular clusters and the galactic system. The colour-magnitude diagram of M55 shows the presence of a population of 56 blue-straggler stars that are more centrally concentrated than the red giant-branch stars.

  15. Infrared photometry of the black hole candidate Sagittarius A*

    NASA Technical Reports Server (NTRS)

    Close, Laird M.; Mccarthy, Donald W. JR.; Melia, Fulvio

    1995-01-01

    An infrared source has been imaged within 0.2 +/- 0.3 arcseconds of the unique Galactic center radio source Sgr A* High angular resolution (averaged value of the Full Width at Half Maximum (FWHM) approximately 0.55 arcseconds) was achieved by rapid (approximately 50 Hz) real-time images motion compensation. The source's near-infrared magnitudes (K = 12.1 +/- 0.3, H = 13.7 +/- 0.3, and J = 16.6 +/- 0.4) are consistent with a hot object reddened by the local extinction A(sub v) approximately 27). At the 3 sigma level of confidence, a time series of 80 images limits the source variability to less than 50% on timescales from 3 to 30 minutes. The photometry is consistent with the emission from a simple accretion disk model for a approximately 1 x 10(exp 6) solar mass black hole. However, the fluxes are also consistent with a hot luminous (L approximately 10(exp 3.5) to 10(exp 4-6) solar luminosity) central cluster star positionally coincident with Sgr A*.

  16. RELATIVE PHOTOMETRY OF HAT-P-1b OCCULTATIONS

    SciTech Connect

    Beky, Bence; Holman, Matthew J.; Noyes, Robert W.; Sasselov, Dimitar D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Gilliland, Ronald L. [Center for Exoplanets and Habitable Worlds, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Bakos, Gaspar A. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544 (United States); Winn, Joshua N., E-mail: bbeky@cfa.harvard.edu [Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States)

    2013-06-01

    We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of two occultations of the transiting exoplanet HAT-P-1b. By measuring the planet to star flux ratio near opposition, we constrain the geometric albedo of the planet, which is strongly linked to its atmospheric temperature gradient. An advantage of HAT-P-1 as a target is its binary companion ADS 16402 A, which provides an excellent photometric reference, simplifying the usual steps in removing instrumental artifacts from HST time-series photometry. We find that without this reference star, we would need to detrend the lightcurve with the time of the exposures as well as the first three powers of HST orbital phase, and this would introduce a strong bias in the results for the albedo. However, with this reference star, we only need to detrend the data with the time of the exposures to achieve the same per-point scatter, therefore we can avoid most of the bias associated with detrending. Our final result is a 2{sigma} upper limit of 0.64 for the geometric albedo of HAT-P-1b between 577 and 947 nm.

  17. Analysis of RGU Photometry in Selected Area 51

    E-print Network

    S. Bilir; S. Karaali; R. Buser

    2004-07-02

    A low-latitude anticenter field (l=189, b=+21) is investigated by using the full calibration tools of RGU photometry. The observed RGU data are reduced to the standard system and the separation of dwarfs and evolved stars is carried out by an empirical method. Stars are categorized into three metallicity classes, i.e. -0.25<[M/H]<=+0.50, -1.00<[M/H]<=-0.25, and [M/H]<=-1.00$ dex, and their absolute magnitudes are determined by the corresponding colour-magnitude diagrams. The unusually large scattering in the two-colour diagrams is reduced by excluding 153 extra-galactic objects, identifying them compared with the charts of Basel Astronomical Institute and University of Minnesota, and by the criterion and algorithm of Gaidos et al. (1993). The local logarithmic space density for giants, D(0)=6.75, lies within the local densities of Gliese (1969) and Gliese & Jahreiss (1992). The local luminosity function for the absolute magnitude interval 3

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

    E-print Network

    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...

  19. HUBBLE SPACE TELESCOPE PHOTOMETRY OF GLOBULAR CLUSTERS IN M81

    SciTech Connect

    Nantais, Julie B. [Departamento de Astronomia, Universidad de Concepcion Av. Esteban Iturra s/n Barrio Universitario Casilla 160-C Concepcion (Chile); Huchra, John P.; Zezas, Andreas; Gazeas, Kosmas; Strader, Jay [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2011-12-15

    We perform aperture photometry and profile fitting on 419 globular cluster (GC) candidates with m{sub V} {<=} 23 mag identified in Hubble Space Telescope/Advanced Camera for Surveys BVI imaging, and estimate the effective radii of the clusters. We identify 85 previously known spectroscopically confirmed clusters, and newly identify 136 objects as good cluster candidates within the 3{sigma} color and size ranges defined by the spectroscopically confirmed clusters, yielding a total of 221 probable GCs. The luminosity function peak for the 221 probable GCs with estimated total dereddening applied is V {approx} (20.26 {+-} 0.13) mag, corresponding to a distance of {approx}3.7 {+-} 0.3 Mpc. The blue and red GC candidates, and the metal-rich and metal-poor spectroscopically confirmed clusters, respectively, are similar in half-light radius. Red confirmed clusters are about 6% larger in median half-light radius than blue confirmed clusters, and red and blue good GC candidates are nearly identical in half-light radius. The total population of confirmed and 'good' candidates shows an increase in half-light radius as a function of galactocentric distance.

  20. CCD time-resolved photometry of faint cataclysmic variables. II

    SciTech Connect

    Szkody, P.; Howell, S.B.; Mateo, M.; Kreidl, T.J. (Washington Univ., Seattle (USA) Planetary Science Institute, Tucson, AZ (USA) Mount Wilson and Las Campanas Observatories, Pasadena, CA (USA) Lowell Observatory, Flagstaff, AZ (USA))

    1989-10-01

    Time-resolved optical broad-band light curves obtained from differential photometry on sequential CCD frames of the known or suspected cataclysmic variable FO And, EH Aqr, WX Cet, XX Cet, AL Com, V503 Cyg, AH Eri, CP Eri, IR Gem, RW UMi, PG0134+070, and US 3215 are presented. The analysis of the light curves with coverage of greater than 2 hrs shows repeatable periodicity in five objects. PG0134+070 exhibits eclipses of 1.3-1.8 mag depth with a period of 313 min. V503 Cyg has a 0.7-1.0 mag peak-to-peak modulation with a period of 109 min. IR Gem shows a large modulation at the orbital period of 99 min, and comparison with previous data indicates that this modulation may have an amplitude dependent on outburst phase. AH Eri reveals a 0.1-0.3 mag modulation, at a period of 42 min. Better time-resolved data on AL Com confirm the 0.4-mag variation reported by Howell and Szkody (1988) at a period of 42 min. These latter two short periods likely indicate magnetic systems. There is also some evidence of periodicity in RW UMi and WX Cet which must be confirmed with further data. 25 refs.

  1. NEOWISE STUDIES OF ASTEROIDS WITH SLOAN PHOTOMETRY: PRELIMINARY RESULTS

    SciTech Connect

    Mainzer, A.; Masiero, J.; Bauer, J.; Hand, E. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T.; Mo, W. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Tholen, D. J. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822-1839 (United States); McMillan, R. S.; Maleszewski, C. [Lunar and Planetary Laboratory, University of Arizona, 1629 East University Blvd., Kuiper Space Science Bldg. 92, Tucson, AZ 85721-0092 (United States); Wright, E.; Watkins, J. [UCLA Division of Astronomy and Astrophysics, P.O. Box 91547, Los Angeles, CA 90095-1547 (United States); Spahr, T. [Minor Planet Center, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Cutri, R. M. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Walker, R. [Monterey Institute for Research in Astronomy, Monterey, CA (United States)

    2012-01-20

    We have combined the NEOWISE and Sloan Digital Sky Survey data to study the albedos of 24,353 asteroids with candidate taxonomic classifications derived using Sloan photometry. We find a wide range of moderate to high albedos for candidate S-type asteroids that are analogous to the S complex defined by previous spectrophotometrically based taxonomic systems. The candidate C-type asteroids, while generally very dark, have a tail of higher albedos that overlaps the S types. The albedo distribution for asteroids with a photometrically derived Q classification is extremely similar to those of the S types. Asteroids with similar colors to (4) Vesta have higher albedos than the S types, and most have orbital elements similar to known Vesta family members. Finally, we show that the relative reflectance at 3.4 and 4.6 {mu}m is higher for D-type asteroids and suggest that their red visible and near-infrared spectral slope extends out to these wavelengths. Understanding the relationship between size, albedo, and taxonomic classification is complicated by the fact that the objects with classifications were selected from the visible/near-infrared Sloan Moving Object Catalog, which is biased against fainter asteroids, including those with lower albedos.

  2. SYNMAG PHOTOMETRY: A FAST TOOL FOR CATALOG-LEVEL MATCHED COLORS OF EXTENDED SOURCES

    SciTech Connect

    Bundy, Kevin; Yasuda, Naoki [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, the University of Tokyo (Kavli IPMU, WPI), Kashiwa 277-8583 (Japan); Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Higgs, Tim D.; Nichol, Robert C.; Masters, Karen L. [Institute for Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Burnaby Road, Portsmouth PO1 3FX (United Kingdom); Lang, Dustin [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Wake, David A. [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States)

    2012-12-01

    Obtaining reliable, matched photometry for galaxies imaged by different observatories represents a key challenge in the era of wide-field surveys spanning more than several hundred square degrees. Methods such as flux fitting, profile fitting, and PSF homogenization followed by matched-aperture photometry are all computationally expensive. We present an alternative solution called 'synthetic aperture photometry' that exploits galaxy profile fits in one band to efficiently model the observed, point-spread-function-convolved light profile in other bands and predict the flux in arbitrarily sized apertures. Because aperture magnitudes are the most widely tabulated flux measurements in survey catalogs, producing synthetic aperture magnitudes (SYNMAGs) enables very fast matched photometry at the catalog level, without reprocessing imaging data. We make our code public and apply it to obtain matched photometry between Sloan Digital Sky Survey ugriz and UKIDSS YJHK imaging, recovering red-sequence colors and photometric redshifts with a scatter and accuracy as good as if not better than FWHM-homogenized photometry from the GAMA Survey. Finally, we list some specific measurements that upcoming surveys could make available to facilitate and ease the use of SYNMAGs.

  3. Effective temperatures and radii of planet-hosting stars from IR photometry

    E-print Network

    I. Ribas; E. Solano; E. Masana; A. Gimenez

    2003-10-16

    In this paper we present and analyse determinations of effective temperatures of planet-hosting stars using infrared (IR) photometry. One of our goals is the comparison with spectroscopic temperatures to evaluate the presence of systematic effects that could alter the determination of metal abundances. To estimate the stellar temperatures we have followed a new approach based on fitting the observed 2MASS IR photometry with accurately calibrated synthetic photometry. Special care has been put in evaluating all sources of possible errors and incorporating them in the analysis. A comparison of our temperature determinations with spectroscopic temperatures published by different groups reveals the presence of no systematic trends and a scatter compatible with the quoted uncertainties of 0.5-1.3%. This mutual agreement strengthens the results of both the spectroscopic and IR photometry analyses. Comparisons with other photometric temperature calibrations, generally with poorer performances, are also presented. In addition, the method employed of fitting IR photometry naturally yields determinations of the stellar semi-angular diameters, which, when combined with the distances, results in estimations of the stellar radii with remarkable accuracies of ~2-4%. A comparison with the only star in the sample with an empirically determined radius (HD 209458 -- from transit photometry) indicates excellent agreement.

  4. Precision Near-Infrared Photometry for Exoplanet Transit Observations. I. Ensemble Spot Photometry for an All-Sky Survey

    NASA Astrophysics Data System (ADS)

    Clanton, C.; Beichman, C.; Vasisht, G.; Smith, R.; Gaudi, B. S.

    2012-07-01

    Near-IR observations are important for the detection and characterization of exoplanets using the transit technique, either in surveys of large numbers of stars or for follow-up spectroscopic observations of individual planets. In a controlled laboratory experiment, we imaged ˜104 critically sampled spots onto an Teledyne Hawaii-2RG (H2RG) detector to emulate an idealized star field. We obtained time-series photometry of up to ?24 hr duration for ensembles of ˜103 pseudostars. After rejecting correlated temporal noise caused by various disturbances, we measured a photometric performance of less than 50 ppm hr-1/2 limited only by the incident photon rate. After several hours we achieved a photon-noise-limited precision level of 10--20 ppm after averaging many independent measurements. We conclude that IR detectors such as the H2RG can make the precision measurements needed to detect the transits of terrestrial planets or to detect faint atomic or molecular spectral features in the atmospheres of transiting extrasolar planets.

  5. Variables Affecting Earth's Albedo

    NSDL National Science Digital Library

    Earth's albedo is the fraction of incoming radiation (sunlight) that is reflected into space. The Earth has an average albedo, which describes how much sunlight is reflected on average for the whole planet and the whole year. The Earth also has a local albedo, which determines how much of the Sun's light is reflected from a particular place at a particular time. The local albedo depends on the particular local surface, which can change seasonally as vegetation changes. It also depends on more rapidly changing things such as snow and clouds. In this lesson, students will investigate one of the variables that affect the Earth's albedo. They will collect and graph data on Earth's albedo from two surface types at the same latitude over a period of two years. They will then use the data to calculate how much difference there is in Earth's albedo between the two locations and suggest reasons for the differences.

  6. Photometry of supernovae in an image series: methods and application to the SuperNova Legacy Survey (SNLS)

    NASA Astrophysics Data System (ADS)

    Astier, P.; El Hage, P.; Guy, J.; Hardin, D.; Betoule, M.; Fabbro, S.; Fourmanoit, N.; Pain, R.; Regnault, N.

    2013-09-01

    Aims: We present a technique to measure lightcurves of time-variable point sources on a spatially structured background from imaging data. The technique was developed to measure lightcurves of SNLS supernovae in order to infer their distances. This photometry technique performs simultaneous point spread function (PSF) photometry at the same sky position on an image series. Methods: We describe two implementations of the method: one that resamples images before measuring fluxes, and one which does not. In both instances, we sketch the key algorithms involved and present the validation using semi-artificial sources introduced in real images in order to assess the accuracy of the supernova flux measurements relative to that of surrounding stars. We describe the methods required to anchor these PSF fluxes to calibrated aperture catalogs, in order to derive SN magnitudes. Results: We find a marginally significant bias of 2 mmag of the after-resampling method, and no bias at the mmag accuracy for the non-resampling method. Given surrounding star magnitudes, we determine the systematic uncertainty of SN magnitudes to be less than 1.5 mmag, which represents about one third of the current photometric calibration uncertainty affecting SN measurements. The SN photometry delivers several by-products: bright star PSF flux measurements which have a repeatability of about 0.6%, as for aperture measurements; we measure relative astrometric positions with a noise floor of 2.4 mas for a single-image bright star measurement; we show that in all bands of the MegaCam instrument, stars exhibit a profile linearly broadening with flux by about 0.5% over the whole brightness range. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii.

  7. Rotational Modulation and Flares on Rs-Canum and By-Draconis Stars - Part Seventeen - Ultraviolet Spectroscopy and Optical Photometry of Au-Microscopii in 1986

    NASA Astrophysics Data System (ADS)

    Quin, D. A.; Doyle, J. G.; Butler, C. J.; Byrne, P. B.; Swank, J. H.

    1993-05-01

    We present IUE spectroscopy and optical photometry of the active late type star AU Mic. The UV spectroscopy allow us to measure the chromospheric and transition region line fluxes. No detectable variations attributable to rotational modulation were evident in either the chromospheric lines or optical bands. We have produced an emission measure curve for the quiescent state of AU Mic, which spans a temperature range 4.0 ? log Te ? 7.6 when coupled with previous X-ray flux measurements. The quiescent radiative losses per unit surface area over the above temperature range is ?8 1O7 erg cm-2 s-1

  8. Campaign Photometry During The 2010 Eclipse Of Epsilon Aurigae

    NASA Astrophysics Data System (ADS)

    Hopkins, Jeff; Stencel, R. E.

    2011-01-01

    Epsilon Aurigae is a long period (27.1 years) eclipsing binary star system with an eclipse that lasts nearly 2 years, but with severe ambiguities about component masses and shape. The current eclipse began on schedule in August of 2009. During the previous, 1982-1984 eclipse, an International Campaign was formed to coordinate a detailed study of the system. While that Campaign was deemed successful, the evolutionary status of the star system remained unclear. Epsilon Aurigae has been observed nearly continuously since the 1982 eclipse. The current Campaign was officially started in 2006. In addition to a Yahoo forum we have a dedicated web site and more than 18 online newsletters reporting photometry, spectroscopy, interferometry and polarimetry data. High quality UBVRIJH band photometric data since before the start of the current eclipse has been submitted. We explore the color differences among the light curves in terms of eclipse phases and archival data. At least one new model of the star system has been proposed since the current Campaign began: a low mass but very high luminosity F star plus a B star surrounded by a debris disk. The current eclipse and in particular the interferometry and spectroscopic data have caused new thoughts on defining eclipsing variable star contact points and phases of an eclipse. Second contact may not be the same point as start of totality and third contact may not be the same point as the start of egress and end of totality. In addition, the much awaited mid-eclipse brightening may or may not have appeared. This paper identifies the current Campaign contributors and the photometric data. This work was supported in part by the bequest of William Herschel Womble in support of astronomy at the University of Denver, by NSF grant 1016678 to the University of Denver.

  9. Precision Photometry to Study the Nature of Dark Energy

    SciTech Connect

    Lorenzon, Wolfgang; Schubnell, Michael

    2011-01-30

    Over the past decade scientists have collected convincing evidence that the expansion of the universe is accelerating, leading to the conclusion that the content of our universe is dominated by a mysterious 'dark energy'. The fact that present theory cannot account for the dark energy has made the determination of the nature of dark energy central to the field of high energy physics. It is expected that nothing short of a revolution in our understanding of the fundamental laws of physics is required to fully understand the accelerating universe. Discovering the nature of dark energy is a very difficult task, and requires experiments that employ a combination of different observational techniques, such as type-Ia supernovae, gravitational weak lensing surveys, galaxy and galaxy cluster surveys, and baryon acoustic oscillations. A critical component of any approach to understanding the nature of dark energy is precision photometry. This report addresses just that. Most dark energy missions will require photometric calibration over a wide range of intensities using standardized stars and internal reference sources. All of the techniques proposed for these missions rely on a complete understanding of the linearity of the detectors. The technical report focuses on the investigation and characterization of 'reciprocity failure', a newly discovered count-rate dependent nonlinearity in the NICMOS cameras on the Hubble Space Telescope. In order to quantify reciprocity failure for modern astronomical detectors, we built a dedicated reciprocity test setup that produced a known amount of light on a detector, and to measured its response as a function of light intensity and wavelength.

  10. Improved mm-wave photometry for kinetic inductance detectors

    NASA Astrophysics Data System (ADS)

    Calvo, M.; Roesch, M.; Désert, F.-X.; Monfardini, A.; Benoit, A.; Mauskopf, P.; Ade, P.; Boudou, N.; Bourrion, O.; Camus, P.; Cruciani, A.; Doyle, S.; Hoffmann, C.; Leclercq, S.; Macias-Perez, J. F.; Ponthieu, N.; Schuster, K. F.; Tucker, C.; Vescovi, C.

    2013-03-01

    Context. We have developed a dual-band (140 and 220 GHz) mm-wave imaging camera based on superconducting kinetic inductance detector (KID) arrays. Each array contains 132 superconducting resonators whose resonant frequencies are shifted by mm-wave photons absorption. The read out is achieved with a single electronics chain per band, taking advantage of the intrinsic KID frequency-domain multiplexability. The arrays are easily scalable and well adapted for future large format focal plane instruments. NIKA (formerly Néel IRAM KID Array, now New IRAM KID Array) has been specifically designed for the IRAM 30 m telescope at Pico Veleta, and is one of the first instruments using KIDs to have made measurements of astronomical sources. Aims: In this Letter we describe the solutions adopted to improve the calibration accuracy and the sensitivity of the instrument, and we report on the outcome of the 3rd NIKA observing run of October, 2011. Methods: We use a fast electronic modulation of the readout tone for each KID pixel in order to linearize the instrument calibration, which we track with measurements of planets. We also adopt a new design of the KIDs, sensitive to both polarizations, to increase the amount of radiation absorbed and thus the optical efficiency of the system. Results: We measured an average sensitivity on the sky of 21 mJys0.5 per beam at 140 GHz and 140 mJys0.5 at 220 GHz in the best observing conditions (?220 ? 0.2) after atmospheric noise decorrelation. The sensitivity at 220 GHz was limited by the atmospheric attenuation and loading as well as a reduction in the spectral bandwidth due to a misplaced filter. We found the repeatability in the photometry over the entire observing run to be better than 10% in both bands, thus demonstrating a significant improvement over the previous runs. We also find good agreement between NIKA measurements of faint astronomical sources and previous measurements of the same sources.

  11. A Remotely Operated Observatory for Minor Planet Photometry

    NASA Astrophysics Data System (ADS)

    Ditteon, Richard

    2008-05-01

    In October of 2007 Rose-Hulman Institute of Technology in Terre Haute, Indiana began operating the Oakley Southern Sky Observatory (E09) located near Siding Spring Observatory in New South Wales, Australia. The observatory houses a 0.5-m, f/8.4 Ritchey-Chretien telescope mounted on a Paramount ME, German equatorial mount. Attached to the telescope is an STL-1001E CCD camera which has 1024 by 1024, 24 µm pixels, a two-stage thermoelectric cooler, and built in color filter wheel with BVRI and clear filters. Image scale is 1.2 arcseconds per pixel. A cloud sensor is used to monitor sky conditions. The observatory has a roll-off roof with limit switches to detect when the roof is fully open and fully closed. In addition, a switch has been added to the mount to detect when the telescope is parked and that it is safe to open or close the roof. All of the hardware is controlled by a custom program which reads a simple text file containing the sequence of images and targets to be collected each night. The text file is loaded onto the control computer once each day, then the software waits until sunset to determine if the sky is clear. When conditions are favorable, power is turned on, the roof opens, twilight flats, dark and bias frames are recorded, and when it is fully dark data frames are recorded. Images are transferred via the Internet back to Rose-Hulman by another program running in the background. The observatory closes itself before dawn or if it gets cloudy. Currently we are using the observatory for photometry of minor planets. Students are responsible for selecting targets, processing the returned images, determining the period and light curve of each minor planet and writing a paper for publication. Recent results will be presented.

  12. The AGB population in IC 1613 using JHK photometry

    NASA Astrophysics Data System (ADS)

    Sibbons, L. F.; Ryan, S. G.; Irwin, M.; Napiwotzki, R.

    2015-01-01

    Context. A member of the Local Group, IC 1613 is a gas rich irregular dwarf galaxy that appears to have formed stars continuously over the last 10 Gyr and is relatively independent of external influences from other galaxies. Aims: This paper aims to study the spatial distribution of the asymptotic giant branch (AGB) population in IC 1613 and its metallicity. Methods: Using WFCAM on UKIRT, high quality JHK photometry of an area of 0.8 deg2 centered on IC 1613 was obtained. The data have been used to isolate the C- and M-type components of the AGB population and using their number ratio, C/M, a global mean metallicity has been derived. The metallicity and the tip of the red giant branch magnitude (TRGB) have been studied as a function of distance from the galactic centre and as a function of azimuthal angle. Results: The TRGB has been found to be at K0 = 18.25 ± 0.15 mag. The colour separation between the C- and M-type components of the AGB population has been located at (J - K)0 = 1.15 ± 0.05 mag, giving a global C/M ratio of 0.52 ± 0.04 and from this an iron abundance of [Fe/H] = -1.26 ± 0.07 dex has been calculated. Conclusions: The AGB population has been detected out to a radial distance of 4.5 kpc in the de-projected plane of the galaxy. The measured TRGB is consistent with previous measurements and no significant variation is detected in the TRGB or in metallicity either with galactocentric distance or azimuthal angle. Full Tables 1 and 2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/573/A84

  13. SECONDARY ECLIPSE PHOTOMETRY OF WASP-4b WITH WARM SPITZER

    SciTech Connect

    Beerer, Ingrid M.; Knutson, Heather A. [Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720 (United States); Burrows, Adam [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 05844 (United States); Fortney, Jonathan J.; Laughlin, Gregory [Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Agol, Eric; Cowan, Nicolas B. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Charbonneau, David; Desert, Jean-Michel [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Deming, Drake [Planetary Systems Laboratory, NASA's Goddard Space Flight Center, Greenbelt MD 20771 (United States); Langton, Jonathan [Department of Physics, Principia College, Elsah, IL 62028 (United States); Lewis, Nikole K.; Showman, Adam P. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

    2011-01-20

    We present photometry of the giant extrasolar planet WASP-4b at 3.6 and 4.5 {mu}m taken with the Infrared Array Camera on board the Spitzer Space Telescope as part of Spitzer's extended warm mission. We find secondary eclipse depths of 0.319% {+-} 0.031% and 0.343% {+-} 0.027% for the 3.6 and 4.5 {mu}m bands, respectively, and show model emission spectra and pressure-temperature profiles for the planetary atmosphere. These eclipse depths are well fit by model emission spectra with water and other molecules in absorption, similar to those used for TrES-3 and HD 189733b. Depending on our choice of model, these results indicate that this planet has either a weak dayside temperature inversion or no inversion at all. The absence of a strong thermal inversion on this highly irradiated planet is contrary to the idea that highly irradiated planets are expected to have inversions, perhaps due the presence of an unknown absorber in the upper atmosphere. This result might be explained by the modestly enhanced activity level of WASP-4b's G7V host star, which could increase the amount of UV flux received by the planet, therefore reducing the abundance of the unknown stratospheric absorber in the planetary atmosphere as suggested in Knutson et al. We also find no evidence for an offset in the timing of the secondary eclipse and place a 2{sigma} upper limit on |ecos {omega}| of 0.0024, which constrains the range of tidal heating models that could explain this planet's inflated radius.

  14. Aperture Photometry Tool Versus SExtractor for Noncrowded Fields

    NASA Astrophysics Data System (ADS)

    Laher, Russ R.; Rebull, Luisa M.; Gorjian, Varoujan; Masci, Frank J.; Fowler, John W.; Grillmair, Carl; Surace, Jason; Mattingly, Sean; Jackson, Ed; Hacopeans, Eugean; Hamam, Nouhad; Groom, Steve; Teplitz, Harry; Mi, Wei; Helou, George; van Eyken, Julian C.; Law, Nicholas M.; Dekany, Richard G.; Rahmer, Gustavo; Hale, David; Smith, Roger; Quimby, Robert M.; Ofek, Eran O.; Kasliwal, Mansi M.; Zolkower, Jeff; Velur, Viswa; Walters, Richard; Henning, John; Bui, Khahn; McKenna, Dan; Kulkarni, Shrinivas R.

    2012-07-01

    Outputs from new software program Aperture Photometry Tool (APT) are compared with similar outputs from SExtractor for sources extracted from R-band optical images acquired by the Palomar Transient Factory (PTF), infrared mosaics constructed from Spitzer Space Telescope images, and a processed visible/near-infrared image from the Hubble Legacy Archive (HLA). Two large samples from the PTF images are studied, each containing around 3×103 sources from noncrowded fields. The median values of source-intensity relative percentage differences between the two software programs, computed separately for two PTF samples, are +0.13% and +0.17%, with corresponding statistical dispersions of 1.43% and 1.84%, respectively. For the Spitzer mosaics, a similar large sample of extracted sources for each of channels 1--4 of Spitzer''s Infrared Array Camera (IRAC) are analyzed with two different sky annulus sizes, and we find that the median and modal values of source-intensity relative percentage differences between the two software programs are between -0.5% and +2.0%, and the corresponding statistical dispersions range from 1.4 to 6.7%, depending on the Spitzer IRAC channel and sky annulus. The results for the HLA image are mixed, as might be expected for a moderately crowded field. The comparisons for the three different kinds of images show that there is generally excellent agreement between APT and SExtractor. Differences in source-intensity uncertainty estimates for the PTF images amount to less than 3% for the PTF sources, and these are potentially caused by SExtractor''s omission of the sky background uncertainty term in the formula for source-intensity uncertainty, as well as differing methods of sky background estimation.

  15. 3D Galactic dust extinction mapping with multiband photometry

    NASA Astrophysics Data System (ADS)

    Hanson, R. J.; Bailer-Jones, C. A. L.

    2014-03-01

    We present a method to simultaneously infer the interstellar extinction parameters A0 and R0, stellar effective temperature Teff and distance modulus ? in a Bayesian framework. Using multiband photometry from Sloan Digital Sky Survey and UKIRT Infrared Deep Sky Survey, we train a forward model to emulate the colour change due to physical properties of stars and the interstellar medium for temperatures from 4000 to 9000 K and extinctions from 0 to 5 mag. We introduce a Hertzsprung-Russell diagram prior to account for physical constraints on the distribution of stars in the temperature-absolute magnitude plane. This allows us to infer distances probabilistically. Influences of colour information, priors and model parameters are explored. Residual mean absolute errors (MAEs) on a set of objects for extinction and temperature are 0.2 mag and 300 K, respectively, for R0 fixed to 3.1. For variable R0, we obtain MAEs of 0.37 mag, 412.9 K and 0.74 for A0, Teff and R0, respectively. Distance moduli are accurate to approximately 2 mag. Quantifying the precisions of individual parameter estimates with 68 per cent confidence interval of the posterior distribution, we obtain 0.05 mag, 66 K, 2 mag and 0.07 for A0, Teff, ? and R0, respectively, although we find that these underestimate the accuracy of the model. We produce two-dimensional maps in extinction and R0 that are compared to previous work. Furthermore, we incorporate the inferred distance information to compute fully probabilistic distance profiles for individual lines of sight. The individual stellar astrophysical parameter (AP) estimates, combined with inferred 3D information, will make possible many Galactic science and modelling applications. Adapting our method to work with other surveys, such as Pan-STARRS and Gaia, will allow us to probe other regions of the Galaxy.

  16. A Comparison of the Published Stellar Photometry Data in the South-West Field of the Galaxy M31 Disk

    E-print Network

    D. Narbutis; R. Stonkute; V. Vansevicius

    2006-10-05

    We compare stellar photometry data in the South-West part of the M31 disk published by Magnier et al. (1992), Mochejska et al. (2001) and Massey et al. (2006) as the local photometric standards for the calibration of star cluster aperture photometry. Large magnitude and color differences between these catalogs are found. This makes one to be cautious in using these data as the local photometric standards for new photometry.

  17. Revisiting the photometry of (308635) 2005 YU_{55} in four colors at McDonald Observatory

    NASA Astrophysics Data System (ADS)

    Ries, J.

    2014-07-01

    We have obtained wide-field CCD images of asteroid (308635) 2005 YU_{55} during November 13-18, 2011, using the McDonald Observatory 0.76-m telescope with a Prime Focus Corrector. The field of view of this instrument is 45' by 45', which allows reliable relative photometry in spite of the substantial sky motion of the object. We planned to take exposures through the B, V, R, and I filters, and spaced the timing to evenly sample the estimated 18-hour rotational period (based on Arecibo radar observations obtained in April 2010). We have also observed Landolt photometric standards on two separate nights under very good sky conditions to calibrate the target either directly or by calibrating the reference stars imaged with the target. We hoped to obtain color indexes and see how the color affects the lightcurve. Unfortunately, due to a glitch of new software installation at that time, the filter entries in the image headers were incorrect. It was easy to correctly identify the actual filters for the Landolt fields, but we had problems separating the V, R, and I images for the actual object. We are using only the images for which the identification is unambiguous, and we have approximately 100 images in R, 80 in V, 40 in B, and 20 in I. Using the phase parameter and the rotational period determined by other studies (Hicks, et al., Warner, et al.), we attempt to reconstruct the lightcurve in V and R and look for possible phase dependence in the (V-R) color index. Although the radar data favors the 19.31-h rotational period (Busch et al.), we will also check whether our data is consistent with the shorter 16.34-h solution. The results will be presented at the meeting.

  18. Luminosity and surface brightness distribution of K-band galaxies from the UKIDSS Large Area Survey

    E-print Network

    Anthony J. Smith; Jon Loveday; Nicholas J. G. Cross

    2009-07-06

    We present luminosity and surface brightness distributions of 40,111 galaxies with K-band photometry from the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS). Various features and limitations of the new UKIDSS data are examined, such as a problem affecting Petrosian magnitudes of extended sources. Selection limits in K- and r-band magnitude, K-band surface brightness and K-band radius are included explicitly in the 1/Vmax estimate of the space density and luminosity function. The bivariate brightness distribution in K-band absolute magnitude and surface brightness is presented and found to display a clear luminosity--surface brightness correlation that flattens at high luminosity and broadens at low luminosity, consistent with similar analyses at optical wavelengths. Best fitting Schechter function parameters for the K-band luminosity function are found to be M*-5 log h=-23.19 +/- 0.04, alpha=-0.81 +/- 0.04 and phi*=(0.0166 +/- 0.0008)h^3 Mpc^{-3}, although the Schechter function provides a poor fit to the data at high and low luminosity, while the luminosity density in the K band is found to be j = (6.305 +/- 0.067) x 10^8 L_sun h Mpc^{-3}. However, we caution that there are various known sources of incompleteness and uncertainty in our results. Using mass-to-light ratios determined from the optical colours we estimate the stellar mass function, finding good agreement with previous results. Possible improvements are discussed that could be implemented when extending this analysis to the full LAS.

  19. Photometry and polarimetry of the nucleus of comet 2P/Encke

    NASA Astrophysics Data System (ADS)

    Boehnhardt, H.; Tozzi, G. P.; Bagnulo, S.; Muinonen, K.; Nathues, A.; Kolokolova, L.

    2008-10-01

    Context: Comet 2P/Encke, a short-period comet, is a favorable target for studies of light scattering by bare cometary nuclei. These studies enable assessment of the nucleus size, the material albedo, and the light-scattering properties of the cometary surface. Observations of 2P/Encke were completed between October to December 2006 when the comet approached the Sun between 2.7 and 2.1 AU. Aims: We characterize the activity of the cometary coma and the physical properties of the nucleus of 2P/Encke such as its size, albedo, colors, spectral slope, surface roughness, porosity, and single-particle properties. Methods: Broadband imaging photometry and broadband and narrowband linear polarimetry is measured for the nucleus of 2P/Encke over the phase-angle range 4-28 deg. Results: An analysis of the point spread function of the comet in polarimetric images reveal only weak coma activity in 2P/Encke, corresponding to dust production of the order of 0.05 kg/s. Over the measured phase-angle range the nucleus displays a color independent photometric phase function of almost linear slope (? = 0.050 ± 0.004 mag/deg). The absolute R filter magnitude at zero phase angle is 15.05 ± 0.05 mag and corresponds to an equivalent radius for the nucleus of 2.43 ± 0.06 km (adopted albedo of 0.047). The nucleus color V-R was measured to be 0.47 ± 0.07, suggesting a spectral slope S' of 11 ± 8%/100 nm. The phase function of linear polarimetry in the V and R filter shows a widely color independent linear increase with phase angle (0.12 ± 0.02%/deg). The test of the empirical albedo-polarization relationship for asteroids reveals unreasonably high albedo values for the nucleus. We find discrepancies in the photometric and polarimetric parameters between 2P/Encke and other minor bodies in the solar system, which may indicate significant differences in the surface material properties and light-scattering behavior of the bodies. Conclusions: The linear polarimetric phase function of 2P/Encke presented here is the first ever measured for a cometary nucleus. It provides encouragement to future studies of cometary nuclei in order to characterize the light-scattering behavior of comets on firm empirical grounds and provide suitable input to a comprehensive modeling of the light scattering by cometary surfaces. Based on observations performed under program 078.C-0509 at the European Southern Observatory, Cerro Paranal, Chile.

  20. Extreme ultraviolet spectroscopy and photometry of VV Puppis during a high accretion state

    NASA Technical Reports Server (NTRS)

    Vennes, Stephane; Szkody, Paula; Sion, Edward M.; Long, Knox S.

    1995-01-01

    We determine the physical properties of the accretion region of the AM Her-type binary VV Puppis using extreme ultraviolet (EUV) medium-resolution spectroscopy and photometry obtained with the Extreme Ultraviolet Explorer (EUVE) observatory. The EUV continuum from VV Pup was detected in the wavelength range from 75 to 135 A and was simultaneously recorded with the Deep Survey/Spectrometer (DS/S) imaging telescope, allowing for the extraction of an accurate light curve. VV Pup appeared to have entered a high-accretion state just prior to the pointed EUVE observations. We use the EUV light curve to infer the diameter of the accretion region (d = 220 km) assuming a hemispherical geometry and a radius of 9000 km for the white dwarf. We perform a model atmosphere analysis and, based on the light curve properties and assuming a distance of 145 pc, we derive an effective temperature of the accretion region in the range 270,000 is less than T(sub eff) is less than 360,000 K and a neutral hydrogen column density in the local interstellar medium of n(sub H) = 1.9 - 3.7 x 10(exp 19)/sq cm. The total EUV/soft X-ray energy radiated by the accretion region is approximately 3.5 x 10(exp 32) ergs/s. Our results provide a first verification of past suggestions that deep heating of the white dwarf surface produces the soft X-ray flux from the polars. We present a possible detection of O VI absortion features, and we suggest that extensive EUVE observations targeting high-accretion events may result in oxygen and heavier element abundance determination in the accretion region.