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1

The surface photometry of NGC 3379  

NASA Astrophysics Data System (ADS)

Surface photometry is carried out for the photometric standard galaxy NGC 3379 on the basis of two plates in the blue band. The results, including luminosity profiles, photometric parameters, integrated luminosity distribution, ellipticity and position angle variation, are presented. The ellipticity and position angle variations reach up to 5 arc mins, much fainter than any previous study. The accuracy of the present data is checked by comparing them with the surface photometry in the literature. It is found that the zero-point about 0.12 mag brighter than the calibration of de Vaucouleurs and Capaccioli (1979), which agrees with the values 0.10-0.15 mag difference claimed by recent observations. The systematic differences is found to be less than about 0.1 mag.

Hu, F. X.; Hamabe, M.; Okamura, S.; Su, H. J.

1989-08-01

2

High-Resolution Surface Photometry of NGC 4314 : Cycle 0  

NASA Astrophysics Data System (ADS)

We propose to obtain ST WF/PC surface photometry of NGC 4314. NGC 4314 exhibits anomalous nuclear activity indicative of on-going star formation. Multicolor surface photometry with 0.1 to 0.4 arcsec resolution will afford an opportunity to explore the global interrelationships between gas clouds, dust, star formation, and stellar populations with detail never before obtained. The expected maximum resolution for for NGC 4314 is 10 parsecs. While most of the data will be secured after the refurb mission with WFPC II, these early I-band exposures will allow studies of structures.

Jefferys

1990-07-01

3

Bibliography of Surface Photometry of galaxies (Davoust+ 1982)  

NASA Astrophysics Data System (ADS)

(adapted from the "Documentation for the Machine-Readable Version of the Detailed bibliography of the surface photometry of galaxies by Lee E. Brotzman and Robert S. Hill (ADC), SASC-T-1-5810-5006-84, July 1984) The bibliography supplies coded information about the methods of observation and reduction, types of photometric data, limiting surface brightness, and the general purpose of each paper for about 650 galaxies and 300 references. (3 data files).

Davoust, E.; Pence, J. D.

1995-06-01

4

GASPHOT: a tool for Galaxy Automatic Surface PHOTometry  

Microsoft Academic Search

In this paper we present a new tool for automatic, blind surface photometry of galaxies in deep and\\/or wide fields. The tool (GASPHOT) favors the robustness of results with respect to the details of galaxy modeling. To this aim, a single Sersic-law for the models and a hybrid 1D\\/2D approach for the best-fitting algorithm were adopted. GASPHOT is heavily based

E. Pignatelli; G. Fasano; P. Cassata

2006-01-01

5

Surface Photometry of Nearby Field Galaxies: The Data  

NASA Astrophysics Data System (ADS)

We have obtained integrated spectra and multifilter photometry for a representative sample of ~200 nearby galaxies. These galaxies span the entire Hubble sequence in morphological type, as well as a wide range of luminosities (MB=-14 to -22) and colors (B-R=0.4-1.8). Here we describe the sample selection criteria and the U, B, R surface photometry for these galaxies. The spectrophotometric results will be presented in a companion paper. Our goals for the project include measuring the current star formation rates and metallicity of these galaxies, and elucidating their star formation histories, as a function of luminosity and morphology. We thereby extend the work of Kennicutt to lower luminosity systems. We anticipate that our study will be useful as a benchmark for studies of galaxies at high redshift. We discuss the observing, data reduction, and calibration techniques and show that our photometry agrees well with previous work in those cases in which earlier data are available. We present an atlas of images, radial surface brightness profiles, and color profiles as well as tables of derived parameters. The atlas and tables of measurements will be made available electronically. We study the correlations of galaxy properties determined from the galaxy images. Our findings include the following: (1) colors determined within the effective radius correlate better with morphological type than with MB and (2) 50% of the low-luminosity galaxies are bluest in their centers.

Jansen, Rolf A.; Franx, Marijn; Fabricant, Daniel; Caldwell, Nelson

2000-02-01

6

Surface photometry of ellipticals: Radio and cluster galaxies  

NASA Astrophysics Data System (ADS)

Broad-band surface photometry in V, R and I colors is presented for three elliptical galaxies immersed in hot intracluster gas emitting X-rays due to thermal bremsstrahlung. The galaxies are (1) a cD galaxy, and (2) a radio bright galaxy with a narrow angle tail in the cluster of galaxies, 2A0335+096, and (3) NGC 3607 in a small nearby group of galaxies. Strong H-alpha emission from NGC 3607 has also been imaged. Detection of a dust ring in NGC 3607 is being reported here for the first time.

Singh, K. P.; Bhat, P. N.; Prabhu, T. P.; Kembhavi, A. K.

1993-09-01

7

Changes on Pluto's Surface Revealed with Long Timebase Photometry  

NASA Astrophysics Data System (ADS)

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.

George, Erin; Buie, M.

2013-10-01

8

Infrared surface photometry of dwarf galaxies in Fornax  

NASA Astrophysics Data System (ADS)

Despite its utility in exploring possible spatial variations in the stellar populations in galaxies, infrared surface photometry of low-luminosity dwarf elliptical (dE) galaxies is generally lacking, due to the technical difficulties in observing low surface brightness objects against the bright infrared sky. Here we attempt to remedy this shortfall to some extent by presenting K-band photometry at arcsecond resolution, including radial profiles, 1D and 2D model fits and the quantification of nuclear components, for a small sample of dE galaxies, with absolute magnitudes MB?-15 to -13, in the Fornax Cluster. In the second part of the paper, we explore the comparison of these data with corresponding optical observations and attempt to interpret this in terms of stellar population models and their radial trends. A significant range of global optical-infrared colours is present in our sample, but radial colour gradients in the galaxies are usually small. However, while the nuclear regions tend to be bluer in optical colours, they are systematically redder than the surrounding galaxy in (R-K). The stellar population modelling suggests that these colour differences are probably an effect of both higher metallicity and younger age in the nuclei. Excluding the nuclear regions, the global colour profiles typically change in the same direction, again indicating older, more metal-poor stellar populations in the outskirts of the galaxies.

Smith, Rachel; Phillipps, S.; Jones, J. B.; Morris, R. A. H.; Smith, R. M.; Drinkwater, M. J.; Karick, A. M.

2012-03-01

9

Multicolor Surface Photometry of Lenticular Galaxies. I. The Data  

NASA Astrophysics Data System (ADS)

We present multicolor surface and aperture photometry in the B, V, R, and K' bands for a sample of 34 lenticular galaxies from the Uppsala General Catalogue. From surface photometric analysis, we obtain radial profiles of surface brightness, colors, ellipticity, position angle, and the Fourier coefficients that describe the departure of isophotal shapes from a purely elliptical form; we find the presence of dust lanes, patches, and ringlike structure in several galaxies in the sample. We obtain total integrated magnitudes and colors and find that these are in good agreement with the values from the Third Reference Catalogue. Isophotal colors are correlated with each other, following the sequence expected for early-type galaxies. The color gradients in lenticular galaxies are more negative than the corresponding gradients in elliptical galaxies. There is a good correlation between B-V and B-R color gradients, and the mean gradients in the B-V, B-R, and V-K' colors are -0.13+/-0.06, -0.18+/-0.06, and -0.25+/-0.11 mag dex-1 in radius, respectively.

Barway, Sudhanshu; Mayya, Y. D.; Kembhavi, Ajit K.; Pandey, S. K.

2005-02-01

10

Unlocking the secrets of stellar haloes using combined star counts and surface photometry  

NASA Astrophysics Data System (ADS)

The stellar haloes of galaxies can currently be studied either through observations of resolved halo stars or through surface photometry. Curiously, the two methods appear to give conflicting results, as a number of surface photometry measurements have revealed integrated colours that are too red to be reconciled with the halo properties inferred from the study of resolved stars. Several explanations for this anomaly have been proposed - including dust photoluminescence, extinction of extragalactic background light and a bottom-heavy stellar initial mass function. A decisive test is, however, still lacking. Here, we explain how observations of the halo of a nearby galaxy, involving a combination of both surface photometry and bright star counts, can be used to distinguish between the proposed explanations. We derive the observational requirements for this endeavour and find that star counts in filters VI and surface photometry in filters VIJ appear to be the optimal strategy. Since the required halo star counts are already available for many nearby galaxies, the most challenging part of this test is likely to be the optical surface photometry, which requires several nights of exposure time on a 4-8 m telescope, and the near-infrared surface photometry, which is most readily carried out using the upcoming James Webb Space Telescope.

Zackrisson, E.; de Jong, R. S.; Micheva, G.

2012-03-01

11

Correlation of the Visual Surface Brightness Parameter with Uvby-Beta Photometry  

NASA Astrophysics Data System (ADS)

The Barnes-Evans relation between a visual surface brightness parameter, FV, and colour index is defined for the (b-y)0 index of uvby ? photometry, the relation being applicable for spectral types ranging from about B0 to about G0.

Moon, T. T.

1984-11-01

12

Optical Photometry of the Martian Surface at Microscopic Scales  

Microsoft Academic Search

The Microscopic Imagers on the Mars Exploration Rovers allow us to acquire unique measurements of the small scale reflectance of Martian soils and rocks at various times of day. These close-up images can be used to determine the light scattering phase function of individual surface components and compare them to the scene average and remote observations. So far, we have

P. E. Geissler; K. Herkenhoff; J. R. Johnson

2006-01-01

13

UBVI Surface Photometry of the Spiral Galaxy NGC 300 in the Sculptor Group  

NASA Astrophysics Data System (ADS)

We present UBVI surface photometry over a 20.5' × 20.5' area of the late-type spiral galaxy NGC 300. We have derived isophotal maps, surface brightness profiles, ellipticity profiles, position angle profiles, and color profiles. By merging our I-band measurements with those of Böker et al. based on Hubble Space Telescope observations, we have obtained combined I-band surface brightness profiles for the region 0.02'' < r < 500'' and have decomposed the profiles into three components: a nucleus, a bulge, and an exponential disk.

Kim, Sang Chul; Sung, Hwankyung; Park, Hong Soo; Sung, Eon-Chang

2004-08-01

14

Optical Photometry of the Martian Surface at Microscopic Scales  

NASA Astrophysics Data System (ADS)

The Microscopic Imagers on the Mars Exploration Rovers allow us to acquire unique measurements of the small scale reflectance of Martian soils and rocks at various times of day. These close-up images can be used to determine the light scattering phase function of individual surface components and compare them to the scene average and remote observations. So far, we have performed the experiment only once with Opportunity, on a soil surface in Meridiani Planum made up of mm-sized hematite-rich spherules mixed with fine grained sand and dust. We have plans to image the soils of Gusev Crater as soon as it is safe to rotate Spirit towards the afternoon sun. The Meridiani images with their 30-?m per pixel resolution show the microscopic shadows cast by the tiny spherules and allow us to separately analyze the reflectance of the spherules and the fines. Over a limited range of phase angles from 27 to 46 degrees, the scene average appears to darken more rapidly with increasing phase angle than a Lambertian surface, because of these microscopic shadows that are unresolved in remote observations. In contrast, the sunlit dust/sand mixture appears quasi-lambertian, whereas the sunlit spherules are slightly forward-scattering. The spherules display prominent specular reflections that contribute to their nonlinear scattering behavior. Changes in the fines from one sol to the next provide evidence of present day aeolian sediment transport, possibly influenced by the proximity of the IDD.

Geissler, P. E.; Herkenhoff, K.; Johnson, J. R.

2006-12-01

15

Multicolour CCD surface photometry for E and S0 galaxies in 10 clusters  

NASA Astrophysics Data System (ADS)

CCD surface photometry for 232 E and S0 galaxies is presented. The galaxies are observed in Gunn r and Johnson B, or Gunn r and g. For 48 of the galaxies surface photometry in Johnson U is also presented. Aperture magnitudes in Gunn nu are derived for half of the galaxies. Galaxies in the following clusters have been observed: Abell 194, Abell 539, Abell 3381, Abell 3574, Abell S639, Abell S753, HydraI (Abell 1060), DC2345-28, Doradus and Grm15. The data are part of our ongoing study of the large-scale motions in the Universe and the physical background for the fundamental plane. We use a full model fitting technique for analysing the CCD images. This gives radial profiles of local surface brightness, colour, ellipticity and position angle. The residuals relative to the elliptical isophotes are described quantitatively by Fourier expansions. Effective radius, mean surface brightness and total magnitude are derived by fitting a de Vaucouleurs r^¼ growth curve. We have derived a characteristic radius r_n similar to the diameter D_n introduced by Dressler et al. The derivation of the effective parameters and of r_n takes the seeing into account. We confirm the results by Saglia et al. that the effects of the seeing can be substantial. Seeing-corrected values of the effective parameters and r_n are also presented for 147 E and S0 galaxies in the Coma cluster. Colours, colour gradients and geometrical parameters are derived. The photometry is internally consistent within 0.016 mag. Comparison with the photoelectric aperture photometry from Burstein et al. shows a mean offset of 0.010 mag with an rms scatter of 0.034 mag. The global photometric parameters are compared with data from Faber et al., Lucey et al. and Lucey & Carter. These comparisons imply that the typical rms errors are as follows - log r_n:+/-0.015 log r_e:+/-0.045 m_T:+/-0.09 mag; _e:+/-0.16 mag. The rms error on the combination log r_e-0.35_e which enters the fundamental plane is +/-0.020. Also, comparisons with data from Saglia et al. are presented. The accuracy of the absolute photometry, as well as the derived parameters, makes the data suitable for our investigations of the fundamental plane and of the large-scale motions in the Universe.

Jorgensen, Inger; Franx, Marijn; Kjaergaard, Per

1995-04-01

16

Surface Photometry and Dynamical Properties of Lenticular Galaxies: NGC3245 as Case Study  

NASA Astrophysics Data System (ADS)

In this paper, surface photometry and dynamical properties of Lenticular galaxies will be developed and applied to NGC3245. In this respect, we established new relation between the intensity distribution I and the semi-major axis a Moreover, some basic statistics of both independent and the dependent variables of the relation are also given. In addition to the I(a) relation, the Sérsic r1/n model is applied for the intensity profile I(r) resulting in an estimation of the effective radius, re, and the surface brightness it encloses, ?e. Both relations (I(a) and I(r)) are accurate as judged by the precision criteria which are: the probable errors for the coefficients, the estimated variance of the fit and the Q value (the square distance between the exact solution and the least square estimated solution) where all very satisfactory. Correlation coefficients between some parameters of the isophotes are also computed. Finally as examples of applications of surface photometry we determined the dynamical properties: mass, density, potential distributions, as well as distributions of escape and circular speeds in terms of Sérsic model.

Sharaf, Mohamed Adel

17

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

NASA Astrophysics Data System (ADS)

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.

Blackman, C. P.

1980-02-01

18

Interstellar matter in Shapley-Ames elliptical galaxies. I. Multicolour CCD surface photometry  

NASA Astrophysics Data System (ADS)

We present accurate CCD surface photometry in Johnson B and V and Cousins I for a complete, magnitude-limited sample of 56 elliptical galaxies from the RSA catalog. For each galaxy we have determined radial profiles of surface brightness, B-V and/or B-I colour index, ellipticity, position angle, and the third- and fourth order Fourier coefficients that describe the deviations of the B, V, and I isophotes from perfect ellipses, using a full two-dimensional fitting technique. The present sample contains 13 galaxies for which no previous isophote analysis has been published, and 26 without published colour gradients. The radial profiles of the ellipticity, position angle, and the third- and fourth-order Fourier coefficients are found to show considerable detail. The profiles are mostly similar in all passbands, except in cases where dust lanes or patches are present. In this respect, the higher-order Fourier coefficients turn out to be sensitive diagnostic tools for the presence of dust in elliptical galaxies. Isophotal deviations from ellipses on the level of 0.5-1% are found to be common in elliptical galaxies. As noted before by others, these deviations are due to structures that do not necessarily align with the apparent major or minor axes of the galaxies, advocating the use of both the cosine and sine higher-order terms in correlation studies. We show that fitting outer radial intensity profiles of elliptical galaxies is an excellent tool for determining the sky background for the surface photometry. The sky values determined from a power-law fit to the outer intensity profiles are found to be within 0.1% of the sky values at the corners of present-day large CCDs where the contribution of galaxy light is negligible. The average colour gradients for the sample galaxies in B-V and B-I are 0.06 and 0.14 mag arcsec^-2^ per decade in radius, respectively. This compares well with colour gradients in elliptical galaxies found by others. The small uncertainty introduced by the sky background determination method applied here results in an average internal uncertainty of only ~ 0.01 mag for our colour gradients, which is significantly better than the results of previous studies. The profiles are compared extensively with results from other authors when available. The result is encouraging, especially for the ellipticity and position angle where we find mean RMS differences of 0.01 and 1.8deg , respectively. The surface brightness profiles generally agree to within +/- 0.0.5mag.

Goudfrooij, P.; Hansen, L.; Jorgensen, H. E.; Norgaard-Nielsen, H. U.; de Jong, T.; van den Hoek, L. B.

1994-04-01

19

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

SciTech Connect

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.

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

20

Local topographic effects on photometry and reflectance spectra of planetary surfaces: An example based on lunar photometry  

Microsoft Academic Search

The photometric properties of the average lunar surface are characterized using Hapke's equations and whole disk observations ranging from 0.36 to 1.06 mum. Synthetic spectra across a crater topographic profile are created using the modeling results. The synthetic spectra are examined for spectral variations created by changes in lighting conditions induced by the topography. Changes above the modeling uncertainties are

Deborah Domingue; Faith Vilas

2007-01-01

21

Low surface brightness galaxies in the Fornax Cluster - Automated galaxy surface photometry. III  

Microsoft Academic Search

A sample of low surface brightness galaxies in the Fornax Cluster region which has been measured by the automated plate measuring machine is presented. Photometric parameters, namely profile shape, scale length, central brightness and total magnitude, are derived for the sample galaxies, and correlations between the parameters of low surface brightness dwarf galaxies are discussed, with particular reference to the

J. I. Davies; S. Phillipps; M. G. M. Cawson; M. J. Disney; E. J. Kibblewhite

1988-01-01

22

Studies of selected voids. Surface photometry of faint galaxies in the direction of 1600+18 in Hercules void.  

NASA Astrophysics Data System (ADS)

Surface photometry, coordinates, magnitudes m(B), diameters, position angles and some morphological parameters are presented for ca. 1850 faint galaxies in a field of one square degree centered at 1600+18 (1950) (Hercules void). The distribution of the magnitudes of the galaxies in this direction is compared with ''Log Normal'' and ''Gauss'' ones and with similar results from SDDS studies of galaxies. Some candidates for primeval galaxies -- 38 large Low surface brightness galaxies were detected in the direction of the void. Major axes luminosity profiles are analyzed. Comparison between two different methods for automatic selection and classification -- a new package, based on MIDAS INVENTORY and SExtractor packages have been made.

Petrov, Georgi

23

Radial Distribution of Stars, Gas, and Dust in SINGS Galaxies. I. Surface Photometry and Morphology  

NASA Astrophysics Data System (ADS)

We present ultraviolet through far-infrared (FIR) surface brightness profiles for the 75 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS). The imagery used to measure the profiles includes Galaxy Evolution Explorer UV data, optical images from Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and Sloan Digital Sky Survey, near-IR data from Two Micron All Sky Survey, and mid- and FIR images from Spitzer. Along with the radial profiles, we also provide multi-wavelength asymptotic magnitudes and several nonparametric indicators of galaxy morphology: the concentration index (C 42), the asymmetry (A), the Gini coefficient (G), and the normalized second-order moment of the brightest 20% of the galaxy's flux (\\overline{M}_{20}). In this paper, the first of a series, we describe the technical aspects regarding the surface photometry, and present a basic analysis of the global and structural properties of the SINGS galaxies at different wavelengths. The homogeneity in the acquisition, reduction, and analysis of the results presented here makes these data ideal for multiple unanticipated studies on the radial distribution of the properties of stars, dust, and gas in galaxies. Our radial profiles show a wide range of morphologies and multiple components (bulges, exponential disks, inner and outer disk truncations, etc.) that vary not only from galaxy to galaxy but also with wavelength for a given object. In the optical and near-IR, the SINGS galaxies occupy the same regions in the C 42-A-G-\\overline{M}_{20} parameter space as other normal galaxies in previous studies. However, they appear much less centrally concentrated, more asymmetric, and with larger values of G when viewed in the UV (due to star-forming clumps scattered across the disk) and in the mid-IR (due to the emission of polycyclic aromatic hydrocarbons at 8.0 ?m and very hot dust at 24 ?m). In an accompanying paper by Muñoz-Mateos et al., we focus on the radial distribution of dust properties in the SINGS galaxies, providing a detailed analysis of the radial variation of the attenuation, the dust column density, the dust-to-gas ratio, the abundance of PAHs, and the intensity of the heating starlight.

Muñoz-Mateos, J. C.; Gil de Paz, A.; Zamorano, J.; Boissier, S.; Dale, D. A.; Pérez-González, P. G.; Gallego, J.; Madore, B. F.; Bendo, G.; Boselli, A.; Buat, V.; Calzetti, D.; Moustakas, J.; Kennicutt, R. C., Jr.

2009-10-01

24

Surface photometry of radio loud elliptical galaxies from the B2 sample  

NASA Astrophysics Data System (ADS)

V-band CCD imaging is presented for 72 galaxies from the B2 radio sample (Colla et al. \\cite{colla}; Fanti et al. \\cite{fanti78}), with redshifts up to 0.2 and radio powers P408=1023-1026.5 W Hz-1. According to the morphology on the optical images 57 galaxies are classified as ellipticals, 6 as spirals and 7 as irregular. Surface photometry of the sample of ellipticals was obtained fitting ellipses to the light distribution. The light profile of these galaxies generally follows a de Vaucouleurs law, although in three cases the profiles show large excesses relative to the r1/4 law at large radii. The fitted mu_e and r_e parameters for the de Vaucouleurs galaxies are given in the paper. Three of the ellipticals show a bright nucleus. One of them is a known broad line radio galaxy (B2 1833+32) and the remaining two are Markarian galaxies, classified in the literature as BL Lac objects (B2 1101+38 and B2 1652+39). The radial profiles for ellipticity, position angle, and B_4 term of the Fourier analysis are presented in the paper, and the morphological peculiarities of the ellipticals are described, including the presence of shells, tails, nuclear dust, isophote twisting, off-centering, and boxiness or diskness of the isophotes. Only one of the galaxies in this work is included in the subsample of B2 radio galaxies with well-defined jets (Parma et al. \\cite{parma87}). In this sense the present sample complements the sample of 24 radio galaxies with well-defined radio jets in Parma et al. for which a similar study was presented in González-Serrano et al. (\\cite{gserrano93}). The irregular galaxy B2 0916+33 appears to be misclassified, and we suggest that the right identification of the radio source is a nearby point like object with V=18.45 mag. The spiral galaxy associated with B2 1441+26 is also misclassified. A point-like optical object with V=18.88 mag, located at ~ 36 arcsec from the original identification and coincident with the radio core is the most probable counterpart. Table 4 is 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 Complete Figure 1 and Figure 2 are only available at http://www.edpsciences.org

González-Serrano, J. I.; Carballo, R.

2000-03-01

25

Magnetic activity of six young solar analogues II. Surface Differential Rotation from long-term photometry  

NASA Astrophysics Data System (ADS)

The present paper is the second of a series dedicated to the study of the magnetic activity in a selected sample of young solar analogues. The sample includes five single G0-G5V stars with ages between =~ 130 Myr and 700 Myr: EK Dra, pi 1 UMa, HN Peg, k1 Cet and BE Cet. In this study we also include the Pleiades-age ( =~ 130 Myr) K0V star DX Leo. Our analysis is based on high precision photometric observations carried out as part of The Sun in Time project, aimed at a multiwavelength study of stars with solar-like global properties, but with different ages and thus at different stages of evolution. In the first paper of this series we presented the photometric observations and determined the existence of starspot cycles and their correlation with the global stellar properties. In the present paper we investigate the surface differential rotation (SDR). The periodogram analysis of the photometric data time series has allowed us to determine the rotational periods and to derive the following results: i) all the selected stars show variations of the rotational period. Such variations are definitely periodic and in phase with the starspot cycle for BE Cet and DX Leo. They are likely periodic and in phase also for pi 1 UMa, EK Dra and HN Peg, but still need confirmation. By analogy with the solar butterfly diagram, the rotational period variations are interpretable in terms of surface differential rotation, that is, they are attributable to the existence of active latitude belts migrating during the activity cycle on a differentially rotating star; ii) BE Cet, pi 1 UMa and EK Dra show a solar-like pattern of SDR, that is the rotational period steadily decreases along the activity cycle, jumping back to higher values at the beginning of the next cycle; on the contrary, DX Leo, k1 Cet and HN Peg show an antisolar pattern; iii) the amplitude of the rotational period variations shows a power law dependence on the rotational period similar to that found in previous studies. Contrary to theoretical predictions, the cycle length is not correlated to the Dynamo number, it is indeed positively correlated to the SDR amplitude. More precisely, stars tend to concentrate along three different branches with the cycle length increasing with increasing Delta Omega /Omega . Moreover, we found that the SDR amplitude changes from cycle to cycle, which is reminiscent of a wave of excess rotation propagating in latitude; iiii) the apparently different solar and antisolar behaviours are probably due to different inclinations of the stellar rotation axis under which the star is seen. The long-term photometry of the young single star LQ Hya, although not included in the initial project, is also used in the present analysis to enlarge the investigated sample. We determined for LQ Hya three different starspot cycles and an antisolar pattern of SDR.

Messina, S.; Guinan, E. F.

2003-10-01

26

Preliminary Results On The Surface Composition Of Centaurs From IRAC/Spitzer Photometry  

NASA Astrophysics Data System (ADS)

Centaurs are a population of icy bodies with probable origin in the trans-Neptunian region. They move in orbits with semimajor axes and perihelia between the orbits of Neptune and Jupiter. The visible colors of the Centaurs show a clear bimodality that divides them into the gray and the red groups. The origin of this peculiar distribution is under debate. It is not yet clear whether the color bimodality is related to their origin or if it is a result of the surface processes that affect the Centaurs. In both cases, these colors are directly related to the surface composition of these bodies, and it is suggested that is a result of variations in the ratio between silicate and organic abundances. Our hypothesis is that the color bimodality extends at wavelengths (?) longer than 2.5 ?m. The aim of this work is to test if the gray group corresponds to objects covered by mantles of silicates, while the red objects are covered, at least in part, by complex organics. The organic materials are typically characterized by an absorption at λ 3 ?m that lies within the bandpass of the IRAC 3.6 ?m filter. We observed 40 Centaurs with Spitzer/IRAC, at 3.6 and 4.5 ?m, in cycles GO2, 4, 6 and GO8. Here, we compare these colors with reflectance values derived from synthetic models. Models of the reflectance from surfaces composed by mixtures of ices, organics and silicates show a wide range of colors at these wavelengths. Thus, measurements of colors of icy bodies beyond 2.5 ?m are a very effective tool to study their surface. Of particular note, silicates and organics have very different reflectance at ? > 3 ?m. We also correlate the colors in the visible and the new colors in the IR to test our hypothesis of the existence of color bimodality also in this wavelength range.

Pinilla-Alonso, Noemi; Emery, J. P.; Trilling, D.; Cruikshank, D. P.; Fernandez, Y.; Dalle Ore, C. M.; Stansberry, J. A.

2013-10-01

27

Astronomical Photometry  

NASA Astrophysics Data System (ADS)

Astronomers use the term "photometry" to refer to the precise measurement of the apparent brightness of astronomical objects in particular specified ranges of electromagnetic wavelength in and near the optically visible band. Historically, this task has been most commonly carried out with the human eye, photographic plates, photomultiplier tubes, and - most recently as of this writing - charge-coupled devices. At wavelengths significantly shorter or longer than the optical region, different detector technologies must be used, and some other term than "photometry" is often used to name the process.

Stetson, Peter B.

28

Deep surface photometry of edge-on spirals in Abell galaxy clusters. Constraining environmental effects  

NASA Astrophysics Data System (ADS)

Context: There is a clear scarcity of structural parameters for stellar thick discs, especially for spiral galaxies located in high-density regions, such as galaxy clusters and compact groups. Aims: We have modelled the thin and thick discs of 4 edge-on spirals located in Abell clusters: NGC 705, ESO 243G49, ESO 187G19, LCSBS 0496P. Deep I band images of NGC 705 were taken from the HST archive, whereas the remaining images were obtained with the Southern Telescope for Astrophysical Research (SOAR) in Gunn r filter. They reached surface brightness levels of ?I ? 26.0 mag arcsec-2 and ?r ? 26.5 mag arcsec-2, respectively. Methods: Profiles were extracted from the deep images, in directions both parallel and perpendicular to the major axis. Profile fits were carried out at several positions, yielding horizontal and vertical scale parameters for both thin and thick disc components. Results: The extracted profiles and fitted disc parameters vary from galaxy to galaxy. Two galaxies have a horizontal profile with a strong down-turn at outer radii, preventing a simple exponential from fitting the entire range. For the 2 early-type spirals, the thick discs have larger scalelengths than the thin discs, whereas no trend is seen for the later types. Both the thin and thick discs sampled tend to have similar scalelengths and scaleheights when compared to typical field disc galaxies. However, the thin disc parameters of the 2 farthest galaxies, both late-type spirals, may be significantly affected by seeing effects. Taken at face value, our results suggest that environment plays a minor role in determining the thin and thick disc sizes.

Santiago, B. X.; Vale, T. B.

2008-07-01

29

Surface Photometry of Celestial Sources from a Space Vehicle: Introduction and Observational Procedures*  

PubMed Central

Diffuse celestial sources of relatively low surface brightness such as the Milky Way, zodiacal light, and gegenschein (or contre lumière) can be studied most reliably from above the earth's atmosphere with equipment flown in artificial satellites. We review the techniques used and some of the difficulties encountered in day-time observations from satellites by the use of a special photometer and polarimeter flown in the orbiting skylab observatory, OSO-6.

Roach, Franklin E.; Carroll, Benjamin; Aller, Lawrence H.; Smith, Leroi

1972-01-01

30

HST Photometry of Triton: Evidence for a Changing Surface in the Outer Solar System  

NASA Astrophysics Data System (ADS)

Triton is one of the few bodies in the solar system with observed cryo-volcanic activity, in the form of plumes (Soderblom et al. 1990). Prompted by evidence from previous observations at ground and space-based telescopes of possible seasonal surface changes on Triton (Young & Stern 1999), we proposed to confirm and characterize these changes using the HST ACS instrument to image Triton at UV, B, V, I and Methane-band wavelengths over as much of its surface as visible from near Earth in 2005. Preliminary analysis indicates a rotation light curve amplitude in excess of that predicted by static models (Hillier et al. 1994 & Hillier 1999) for visual wavelengths, and significant departures from observations taken 12 years earlier in the UV. Surface brightness maps generated from the data show significant departures from the Voyager images obtained in 1989. We will describe in detail these differences which set constraints on activity and surface temperature as well as composition. Such constraints have profound implications for our understanding of Triton's evolution as well as the history of other outer solar system bodies that may undergo similar geophysical processes or have similar composition, such as Pluto (Buratti et al. 2003, Young et al. 2001). References Buratti, B.J., Hillier, J.K., Heinze, A.,Hicks, M.D., Tryka, K.A., Mosher, J.A., Ward, J., Garske, M., Young, J., & Atienza-Rosel, J. Icarus, 162, 171. Hillier, J., Veverka, J., Helfenstein, P., & Lee, P. 1994, Icarus, 109, 296. Hillier, J.K. 1999, Icarus, 139, 202. Soderblom, L.A., Becker, T.L., Kieffer, S.W., Brown, R.H., Hansen, C.J., & Johnson, T.V. 1990, Science, 250, 410. Young, L.A., & Stern, A.S. 1999, AJ, 122, 449. Young, E. F.; Binzel, R. P.; Crane, K. 2001, AJ, 121, 552.

Bauer, James M.; Buratti, B. J.; Li, J. Y.; Hicks, M. D.; Goguen, J. D.; Pilorz, S.; Schmidt, B.; Royle, P.; Herbert, B.; Cobb, B.; Ward, J.; Wright, E.; Acton, C.

2008-09-01

31

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

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

32

The Westerbork HI survey of spiral and irregular galaxies. II. R-band surface photometry of late-type dwarf galaxies  

NASA Astrophysics Data System (ADS)

R-band surface photometry is presented for 171 late-type dwarf and irregular galaxies. For a subsample of 46 galaxies B-band photometry is presented as well. We present surface brightness profiles as well as isophotal and photometric parameters including magnitudes, diameters and central surface brightnesses. Absolute photometry is accurate to 0.1 mag or better for 77% of the sample. For over 85% of the galaxies the radial surface brightness profiles are consistent with published data within the measured photometric uncertainty. For most of the galaxies in the sample H I data have been obtained with the Westerbork Synthesis Radio Telescope. The galaxies in our sample are part of the WHISP project (Westerbork H I Survey of Spiral and Irregular Galaxies), which aims at mapping about 500 nearby spiral and irregular galaxies in H I. The availability of H I data makes this data set useful for a wide range of studies of the structure, dark matter content and kinematics of late-type dwarf galaxies. Based on observations made with INT operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. The tables in Appendix A 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/cgi-bin/qcat?J/A+A/390/863. The figures in Appendix B are only available in electronic form http://www.edpsciences.org

Swaters, R. A.; Balcells, M.

2002-08-01

33

Hierarchical titanium surface textures affect osteoblastic functions.  

PubMed

This study investigated the surface characteristics and in vitro cytocompatibility of hierarchical textured titanium surfaces with nanograins and microroughness, produced by surface mechanical attrition treatment (SMAT). The surface characteristics were evaluated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, contact angle, and surface energy measurements. The in vitro cytocompatibility of the SMAT processed surfaces (hereafter Ti-SMAT surfaces) were assessed in terms of cellular attachment, morphology, viability, alkaline phosphatase (ALP) activity, and mRNA gene expression. Two other titanium surfaces were compared: well-polished Ti6Al4V surfaces (hereafter Ti-polish surfaces) and thermally sprayed rough surfaces (hereafter Ti-spray surfaces). The Ti-SMAT surfaces showed a higher hydrophilicity and increased surface energy compared with the Ti-polish and Ti-spray surfaces. Consequently, these Ti-SMAT surfaces demonstrated enhancement of cell attachment, spreading, viability, and ALP activity. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed significantly higher ALP activity and stronger expression of mRNA levels of key osteoblast genes in cells grown on the Ti-SMAT surfaces than the other two surfaces. These results reveal a synergic role played by nanostructure and microtopography in osteoblastic functions and demonstrate the more promising cytocompatibility of the hierarchical textured surfaces. It is suggested that the SMAT process may provide a novel method of surface modification to the currently available metallic biomaterials. PMID:21972107

Zhao, Changli; Cao, Peng; Ji, Weiping; Han, Pei; Zhang, Jihong; Zhang, Fan; Jiang, Yao; Zhang, Xiaonong

2011-10-03

34

Galaxy Photometry  

NSDL National Science Digital Library

This activity asks students to observe the images of three spiral galaxies of different surface brightnesses. Each of the loaded images is active in the sense that you can place a rectangular aperture on them and determine the flux. The flux through the aperture equals the galaxy flux + the sky flux. Hence to determine the galaxy flux you need to put an aperture on the sky background (where there is little or no galaxy light) and measure that.

Department, University O.

2005-06-17

35

Spectral and spatial dependency of aerosol extinction in the upper troposphere based on the moon surface photometry in the Earth's umbra  

NASA Astrophysics Data System (ADS)

The work is based on photometry of the Moon's surface during the total lunar eclipse of June 15, 2011. Photometric data are used to retrieve the value of aerosol extinction coefficient in the troposphere above the Earth's limb in various spectral bands in the optical and near-IR ranges. The results are analyzed in comparison with the data of previous eclipses in 2004-2008. The main result consists in an increased aerosol concentration in the South-East Asia, which is maximum among all eclipses observed in recent years. At the same time, no relationship between eclipse brightness and solar activity is observed, as well as unified latitude dependency of umbra brightness noticed earlier.

Ugolnikov, O. S.; Maslov, I. A.; Korotkiy, S. A.

2012-09-01

36

Phytoplankton physiology can affect ocean surface temperatures  

Microsoft Academic Search

A key biological link between ocean geochemical cycles, ocean color and sea surface temperature (SST) is the nitrogen-to-chlorophyll a (N:chl a) ratio of phytoplankton. This is because nitrogen is the limiting factor over approximately 2\\/3 of the ocean surface and light absorption depends on the concentration of chlorophyll a. Recent work has demonstrated systematic variability in this ratio. Using one-dimensional

Nathalie Lefèvre; Arnold H. Taylor; Richard J. Geider

2001-01-01

37

Surface photometry and radial color gradients of nearby luminous early-type galaxies in SDSS Stripe 82  

NASA Astrophysics Data System (ADS)

We make use of the images from the Sloan Digital Sky Survey Stripe 82 (Stripe 82) to present an analysis of r band surface brightness profiles and radial color gradients (g-r, u-r) in our sample of 111 nearby early-type galaxies (ETGs). Thanks to the Stripe 82 images, each of which is co-added from about 50 single frames, we are able to pay special attention to the low-surface-brightness areas (LSB areas) of the galaxies. The LSB areas affect the Sérsic fittings and concentration indices by making both of the indices less than the typical values for ETGs. In the Sérsic fits to all the surface brightness profiles, we found some Sérsic indices that range from 1.5 to 2.5, much smaller than those of typical de Vaucouleur profiles and relatively close to those of exponential disks, and some others much larger than four but still with accurate fitting. Two galaxies cannot be fitted with a single Sérsic profile, but once we try double Sérsic profiles, the fittings are improved: one with a profile relatively close to the de Vaucouleur law in the inner area and a profile relatively close to an exponential law in the LSB area, the other with a nice fitting in the inner area but still having a failed fitting in the outer area. About 60% of the sample has negative color gradients (red-core) within 1.5 Re, much more than the approximately 10% positive ones (blue-core) within the same radius. However, taking into account the LSB areas, we find that the color gradients are not necessarily monotonic: about one third of the red-core (or blue-core) galaxies have positive (or negative) color gradients in the outer areas. So LSB areas not only make ETGs' Sérsic profiles deviate from de Vaucouleur ones and shift to the disk end, but also reveal that quite a number of ETGs have opposite color gradients in inner and outer areas. These outcomes remind us of the necessity of double-Sérsic fitting. These LSB phenomena may be interpreted by mergers and thus have different metallicity in the outer areas. Isophotal parameters are also discussed briefly in this paper with the following conclusion: there are more disky nearby ETGs that are identified than boxy ones.

Jiang, Fang-Zhou; Huang, Song; Gu, Qiu-Sheng

2011-03-01

38

Remote determination of small-scale three-dimensional surface properties based on imaging photometry and polarimetry: an introduction  

NASA Astrophysics Data System (ADS)

The remote sensing analysis of planetary surfaces is a field in which photopolarimetric techniques allow the estimation of the average small-scale 3D properties of the examined surfaces (i.e. on millimeter or sub-millimeter scales) from large distances. This work provides an overview of image-based photometric and polarimetric methods for the remote determination of small-scale 3D properties of planetary regolith surfaces. Specifically, the surface porosity governs the phase angle dependence of the reflectance function of the surface material for near-zero phase angles, while the reflectance behavior at large phase angles between around 90° and 180° allows to estimate the surface roughness on sub-millimeter and millimeter scales. For the lunar regolith, a calibration of the phase angle dependence of the polarization behavior of the light reflected from the surface based on returned lunar sample material provides a framework to determine the median regolith grain size based on measurements of the polarization degree. In this work, the corresponding methodologies as well as their application to specific planetary bodies are discussed. Where deemed favorable, new photometric and polarimetric measurements of prototypical areas of the lunar surface are provided to exemplify the described approaches in an illustrative manner. [Figure not available: see fulltext.

Wöhler, Christian

2010-12-01

39

Factors Affecting the Retention Decisions of Female Surface Warfare Officers.  

National Technical Information Service (NTIS)

This thesis delineates factors affecting the retention decisions of female Surface Warfare Officers. The data were obtained from in-depth interviews conducted with 12 female senior officers and 15 female junior officers. The transcripts from the interview...

E. A. Clifton

2003-01-01

40

How does surface life affect interior geological processes?  

Microsoft Academic Search

How does surface life affect interior geological processes? We propose that biologically-mediated processes operating on the surface of the Earth need to be incorporated into our understanding of the geological evolution of the Earth. We argue that biotic effects may penetrate the lithosphere and be responsible for altering the dynamics of mantle convection. Geological processes have played a fundamental role

James Dyke; Fabian Gans; Axel Kleidon

2010-01-01

41

Produce Surface Characteristics Affect Product Quality and Safety  

Technology Transfer Automated Retrieval System (TEKTRAN)

The surface characteristics of fresh-cut fruits and vegetables vary largely among produce types, maturities and processing procedure. Studies have shown that the surface topography of produce significantly affected adherence, attachment, and biofilm formation of bacteria, as well as their removal a...

42

Photometry of M33  

NASA Astrophysics Data System (ADS)

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.

Schlingman, W. M.; Massey, P.

2003-12-01

43

Photometry with FORS  

NASA Astrophysics Data System (ADS)

Photometric calibration observations are routinely carried out with all ESO imaging cameras in every clear night. The nightly zeropoints derived from these observations are accurate to about 10%. Recently, we have started the FORS Absolute Photometry Project (FAP) to investigate, if and how percent-level absolute photometric accuracy can be achieved with FORS1, and how such photometric calibration can be offered to observers. We found that there are significant differences between the sky-flats and the true photometric response of the instrument which partially depend on the rotator angle. A second order correction to the sky-flat significantly improves the relative photometry within the field. We demonstrate the feasibility of percent level photometry and describe the calibrations necessary to achieve that level of accuracy.

Freudling, W.; Møller, P.; Patat, F.; Moehler, S.; Romaniello, M.; Jehin, E.; O'Brien, K.; Izzo, C.; Pompei, E.

44

Factors affecting the productivity of loaders in surface mines  

Microsoft Academic Search

Wheel loaders are deployed as primary loading machines in surface mines due to their mobility and low operating cost. The productivity of wheel loaders or any other loading machine is affected by several factors. One of the most significant factors is the characteristic of the muck being loaded. A study was conducted to examine the effects of the looseness, angle

S. P. Singh; R. Narendrula

2006-01-01

45

CCD Photometry of the Centaur 1995 GO  

Microsoft Academic Search

We present new CCD photometry of the Centaur object 1995 GO obtained in April 1996, including a lightcurve, aV ? Rcolor, and a surface brightness profile. The apparent brightness implies a circular effective radius of 53.5 km, assuming a 4% albedo. The shape of the lightcurve is compatible with an aspherical rotating body, with a rotation period of 8.870 ±

Warren R. Brown; Jane X. Luu

1997-01-01

46

Gaia broad band photometry  

Microsoft Academic Search

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

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

2010-01-01

47

Photometry with GAIA  

NASA Astrophysics Data System (ADS)

The ESA GAIA spacecraft has been approved for launch by a Soyuz-Fregat launcher in December 2011. After five years continuously scanning the sky, astrometric, photometric and spectroscopic data for a billion objects down to V˜20 will be acquired. That huge survey of the Galaxy content and beyond will provide insights to the origin and evolution of the Galaxy, to stellar astrophysics, to solar system objects, to QSOs, and so on. GAIA is the successor of the successful { HIPPARCOS mission and it means a big step forward, both in terms of number of objects and in terms of precision. The final industrial approach to photometry includes two slitless spectrographs, covering the blue and the red parts of the radiation spectrum from 330 to 1050 nm. Photometry will be acquired by a white photometric band, and by two low-dispersion spectra. Now, there is a unique focal plane integrating astrometry, photometry and spectroscopy. In this paper, we review the goals of GAIA photometry, and present as well the new low-dispersion spectrophotometry approach. With the redesign of the mission, the reduction process changes considerably and a great effort must be devoted to this issue in the next years.

Jordi, C.; Carrasco, J. M.

2007-04-01

48

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

49

Factors affecting slab surface roughness of siliceous dimension stones  

Microsoft Academic Search

The sawing of granite blocks using multi-blade gangsaws and an abrasive mixture is one of the most complex operations in the\\u000a rock transformation industry. The surface quality of the finished slabs is the main determinant of the volume of material\\u000a to be removed in subsequent polishing operations, thus affecting the product’s final cost. Measurements carried out on five\\u000a types of

Rogério Pinto Ribeiro; Antenor Braga Paraguassú; Sérgio Trajano Franco Moreiras

50

Gaia broad band photometry  

NASA Astrophysics Data System (ADS)

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

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

51

Photometry with NICMOS  

NASA Astrophysics Data System (ADS)

We summarize the performance of the NICMOS instrument and discuss the measured sensitivity, and the photometric performance and stability. We also present a method for removing an instrument artifact termed ``pedestal'', a bias instability that is present at a low level in most NICMOS images. The characteristics of dark frames will also be discussed, in particular as they relate to pedestal correction. NICMOS is capable of achieving the advertised performance in most areas. As an example, typical 3 sigma detection limits for a 5 orbit observation with NIC2 are 1.47 mJy arcsec(-2) in F110W, 1.67 mJy arcsec(-2) in F160W, and 12.6 mJy arcsec(-2) in F222M. The absence of time-dependent backgrounds makes infrared photometry from NICMOS highly stable, reaching an accuracy of 2% or better. NICMOS absolute calibration has been accomplished with a combination of solar analog stars and white dwarf standard stars and achieves 5% absolute photometry. An exception to these accuracies occurs for NIC3 at short wavelengths where intra-pixel sensitivity variations produces variations in relative photometry as large as 20%.

Calzetti, D.; Dickinson, M. E.; Bergeron, L. E.; Colina, L.

1998-12-01

52

How does stratospheric variability affect surface weather and climate?  

NASA Astrophysics Data System (ADS)

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.

Baldwin, Mark; Birner, Thomas

2013-04-01

53

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

SciTech Connect

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.

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

54

CCD Photometry of Variables Stars  

NASA Astrophysics Data System (ADS)

With recent advances in Charged Coupled Devices (CCDs), it is now possible to do high speed CCD photometry. Though photelectric photometry has a rich history and many years of software development, CCDs have several advantages over photometers: They have a higher quantum efficiency and eliminate many of the problems associated with the requirement of a fixed aperture in photoelectric photometry. However, CCD photometry has yet to develop the necessary tools to efficiently reduce and analyze the quantities of time-series data produced. Two other areas where advancement is needed are in decreasing the CCD readout times and producing real time light curves. We present steps taken to address these two issues. Dead times were shortened by examining various CCD geometries and scripts were written to process the data more efficiently. Our work has produced efficient methods for obtaining and reducing high speed CCD observations and brings us a step closer to producing real time light curves.

Jeffery, E. J.; Reed, M. D.

2001-12-01

55

Photometry and the Virtual Observatory  

NASA Astrophysics Data System (ADS)

Building Spectral Energy Distributions combining data from different sources is becoming more important as astronomy takes an increasingly multi-wavelength approach. In order to do this, photometry data must be described in sufficient detail to allow for the conversion to compatible flux density units (including the description of magnitude systems and zero points). Furthermore, comparing observed photometry with the synthetic one for theoretical models allows to infer physical properties from the observed objects. But in order to do that, an even more detailed description of the observed photometric points is needed, including the transmission curves of the filters corresponding to the observed data. In the Virtual Observatory an important effort has been done towards this standardization with the Photometry Data Model. And in the SVO we have developed several services to help in this direction, providing detailed information about filters, synthetic photometry for theoretical models and tools to use all this to analyze observed data and estimate object physical properties.

Rodrigo, C.; Solano, E.

2013-05-01

56

Deep CCD photometry of spiral galaxies  

NASA Astrophysics Data System (ADS)

This study presents deep optical surface photometry in the R-band for the three spiral galaxies NGC 1003, NGC 5533, and NGC 6674. The luminosity profiles, derived by fitting ellipses to the isophotes, are decomposed into bulge and disk contributions using the method proposed by Kent (1986). The intrinsic bulge and disk axis ratios, used in the iterative scheme, are 0.71 and 0.59 for NGC 5533, 0.44 and 0.33 for NGC 1003, and 0.90 and 0.50 for NGC 6674.

Broeils, A. H.; Knapen, J. H.

1991-12-01

57

Titanium surface topography affects collagen biosynthesis of adherent cells.  

PubMed

Collagen-dependent microstructure and physicochemical properties of newly formed bone around implant surfaces represent key determinants of implant biomechanics. This study investigated the effects of implant surface topography on collagen biosynthesis of adherent human mesenchymal stem cells (hMSCs). hMSCs were grown for 0 to 42 days on titanium disks (20.0 × 1.0 mm) with smooth or rough surfaces. Cell attachment and spreading were evaluated by incubating cells with Texas-Red-conjugated phalloidin antibody. Quantitative real-time PCR was used to measure the mRNA levels of Col1?1 and collagen modifying genes including prolyl hydroxylases (PHs), lysyl oxidases (LOXs) and lysyl hydroxylases (LHs). Osteogenesis was assessed at the level of osteoblast specific gene expression and alizarin red staining for mineralization. Cell layer-associated matrix and collagen content were determined by amino acid analysis. At 4h, 100% cells were flattened on both surfaces, however the cells on smooth surface had a fibroblast-like shape, while cells on rough surface lacked any defined long axis. PH, LH, and most LOX mRNA levels were greater in hMSCs grown on rough surfaces for 3 days. The mineralized area was greater for rough surface at 28 and 42 days. The collagen content (percent total protein) was also greater at rough surface compared to smooth surface at 28 (36% versus 26%) and 42 days (46% versus 29%), respectively (p<.05). In a cell culture model, rough surface topography positively modulates collagen biosynthesis and accumulation and the expression of genes associated with collagen cross-linking in adherent hMSC. The altered biosynthesis of the collagen-rich ECM adjacent to endosseous implants may influence the biomechanical properties of osseointegrated endosseous implants. PMID:21549232

Mendonça, Daniela B S; Miguez, Patrícia A; Mendonça, Gustavo; Yamauchi, Mitsuo; Aragão, Francisco J L; Cooper, Lyndon F

2011-04-27

58

Soil Factors Affecting Mycorrhizal Use in Surface Mine Reclamation.  

National Technical Information Service (NTIS)

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 bi...

M. R. Norland

1993-01-01

59

SURFACE TENSION OF SERA AS AFFECTED BY THE PRECIPITIN REACTION  

PubMed Central

An attempt to find evidence, through the study of surface tension, using the du Noüy tensiometer, of a denaturing effect of the precipitin reaction upon either the antigen or the immune serum yielded entirely negative results.

Ramsdell, Susan Griffith

1928-01-01

60

Color Presentation Mode Affects Human Haptic Memory for Rough Surfaces  

Microsoft Academic Search

For the design of haptic (tactile) interfaces, it is important to learn how haptic effects are learned, memorized and later used for interaction with computers. To our knowledge, less or little is known about the recognition memory for haptic information. The authors used a recognition memory paradigm to study the interaction of colors on human haptic memory for rough surfaces.

Zhaowu Luo; Atsumi Imamiya

2003-01-01

61

Time Series Photometry of the Youngest Stars - MIPS24 Photometry for IC1396A  

NASA Astrophysics Data System (ADS)

We have recently obtained IRAC time-series photometry of the embedded, very young cluster of young stellar objects (YSOs) in the Elephant's Trunk Nebula (a.k.a. IC1396A). About 20% of the YSOs, including about half of the Class I stars, showed relatively large amplitude (> 0.1 mag) variability with characteristic timescales of 4 to 15 days, and with very little difference in light curve shape and amplitude between 3.6 and 8 microns. The most plausible physical model for these variations is that we are seeing these stars primarilyin scattered light all the way out to 8 microns, and that the sources of the variability are hot spots (from accretion flows) on the surfaces of these stars. In order to place further constraints on models for these stars, we propose to obtain MIPS24 photometric observations of the 5'x5' "head" of the IC1396A star-forming globule at sixteen epochs, about twice per day, during a single MIPS campaign. We will also obtain a small amount of new IRAC time-series photometry in an adjacent campaign in order to place the MIPS photometry in better context with the existing IRAC light curves obtained in February 2008. The entire set of observations requires 3.6 hours of observing time.

Stauffer, John; Carey, Sean; Hartmann, Lee; Hillenbrand, Lynne; Morales, Maria; Rebull, Luisa; Werner, Michael

2008-08-01

62

Free-surface stability criterion as affected by velocity distribution  

USGS Publications Warehouse

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

Cheng-Lung, Chen

1995-01-01

63

Surface properties and implantation site affect the capsular fibrotic overgrowth.  

PubMed

Transplantation of encapsulated pancreatic islets is a promising approach for the treatment of type 1 diabetes. Large-scale application of this technique, however, is hampered by insufficient biocompatibility of the capsules. In this study, we have evaluated the biocompatibility of a new synthetic material with six different chemical groups on their surface (amino, carboxy-sulfate, carboxylate, hydroxylate, sulfate, and PMMA) used for the fabrication of the microcapsules. Eight Lewis rats were inoculated with a suspension of empty capsules made for each candidate material in the retroperitoneal ileopsoas muscle and renal subcapsular space. Four weeks later kidney and muscle containing the capsules were explanted, paraffin embedded, sectioned and stained with Sirius Red and Masson's Trichrome for histological analysis. The amount of fibrosis was also ultrastructurally evaluated with scanning electron microscopy. The samples were then subjected to digitalized quantitative analysis using specific software to determine the degree of fibrotic overgrowth. The quantification of collagen deposition, calculated in proximity of the microcapsules, was expressed as a percentage of the total area and can be considered a good index for the biocompatibility, an essential prerequisite for functional pancreatic islet transplantation. The results show that subcapsular renal space is the best implantation site and the positive surface charge induces a more intense collagen synthesis. PMID:17580325

Bakeine, G J; Bertolotti, A; Latina, M; Congiu, T; Prati, U; Roveda, L; Trotta, F; Tormen, M; Fabrizio, E Di; Carlini, G; Facoetti, A; Nano, R

2007-12-15

64

Factors Affecting Survival of Bacteriophage on Tomato Leaf Surfaces?  

PubMed Central

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.

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

2007-01-01

65

Laser speckle photometry: contactless nondestructive testing technique  

NASA Astrophysics Data System (ADS)

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.

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

66

Does mineral surface area affect chemical weathering rates?  

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

67

Photometry of Phoebe  

NASA Astrophysics Data System (ADS)

The nonsynchronous rotational period and light curve for Phoebe are analyzed. The variations in CCD chip pixel response, the intensity of the images, the sky background level, and the atmospheric effects and color response of the detector are examined. Consideration is also given to brightness variations and the solar phase function at small phase angles (0.2-1.2 deg) of the light curve. The Phoebe surface is compared with asteroid surfaces by fitting the data to a linear phase function. It is determined that the Phoebe's sidereal rotational period is refined to 9.282 + or - 0.015 hr, the light curve in V filter exhibits 20 percent brightness variations with weaker higher-order harmonics, and the solar phase coefficient at angles less than 1.2 deg is 0.180 + or 0.035 mag/deg. The Phoebe data at small phase angles correlated well with a phase function for C-type asteroids.

Kruse, S.; Klavetter, J. J.; Dunham, E. W.

1986-10-01

68

Voyager photometry of Io  

SciTech Connect

Detailed disk-integrated and disk-resolved photometric studies of the Jovian moon Io were carried out using Voyager images. Disk-integrated properties derived from the Voyager data, such as phase curves, rotation curves, geometric albedos, phase integrals, and the Bond albedo, are generally consistent with earth-based estimates. Near-opposition limb-darkening behavior, as parameterized by the Minnaert photometric function, has been accurately measured for regions on the surface of Io in three distinct color classes: Bright (white), Average (orange), and Polar (brown). The limb-darkening results allow derivation of accurate near-opposition disk-resolved phase curves, revealing substantial differences in opposition surge among the color classes. Modeling of the phase curves using the Hapke photometric function supports the contention that the uppermost layer of the Ionian surface is on average extremely porous, and suggests that this layer is substantially more porous in Average and Polar areas than in the Bright regions, a difference consistent with models of Io's surface layer. Combination of limb-darkening and phase information leads to determination of accurate normal reflectance spectra for the color classes; careful comparison with laboratory data supports earlier claims that the spectra of Ionian materials can be explained by mixtures of sulfur and SO/sub 2/ frost, although this is not a unique diagnostic identification.

Simonelli, D.P.

1987-01-01

69

UBV photometry of ER Vulpeculae  

Microsoft Academic Search

UBV photometry of the RS CVn-type eclipsing binary system ER Vulpeculae has been presented. The period comes out to be 0.698093d. The average depths of primary and secondary minima are, respectively, 0.21 and 0.12m. The colors at various phases have been given. A dip is seen around phase 0.73P as was seen in the observations of Arevalo et al. (1988).

R. K. Srivastava; T. D. Padalia; J. B. Srivastava

1991-01-01

70

IMF, Extinction Law, and Stellar Populations in Dwarf Galaxies - Global Photometry of the LITTLE THINGS Galaxies  

NASA Astrophysics Data System (ADS)

We have assembled a multi-wavelength dataset, including deep interferometric HI maps, on a representative sample of 41 relatively nearby gas-rich dwarf irregular galaxies (LITTLE THINGS or LT). These data trace stellar populations, gas content, and dynamics for the purpose of testing and modifying star formation models. Here we present preliminary analysis of global photometry for 37 galaxies (two are not included in the LT sample). We include GALEX FUV/NUV, optical UBV, and IRAC 3.6?m photometry. Surface photometry was done for all bands with the same elliptical apertures.

Zhang, H.; Hunter, D.; Little Things Team

2011-06-01

71

Difference image photometry with bright variable backgrounds  

NASA Astrophysics Data System (ADS)

Over the last two decades the Andromeda galaxy (M31) has been something of a test-bed for methods aimed at obtaining accurate time-domain relative photometry within highly crowded fields. Difference imaging methods, originally pioneered towards M31, have evolved into sophisticated methods, such as the optimal image subtraction (OIS) method of Alard & Lupton, that today are most widely used to survey variable stars, transients and microlensing events in our own Galaxy. We show that modern difference image analysis (DIA) algorithms such as OIS, whilst spectacularly successful towards the Milky Way bulge, may perform badly towards high surface brightness targets such as the M31 bulge. Poor results can occur in the presence of common systematics which add spurious flux contributions to images, such as internal reflections, scattered light or fringing. Using data from the Angstrom Project microlensing survey of the M31 bulge, we show that very good results are usually obtainable by first performing careful photometric alignment prior to using OIS to perform point spread function (PSF) matching. This separation of background matching and PSF matching, a common feature of earlier M31 photometry techniques, allows us to take full advantage of the powerful PSF matching flexibility offered by OIS towards high surface brightness targets. We find that difference images produced this way have noise distributions close to Gaussian, showing significant improvement upon results achieved using OIS alone. We show that with this correction light curves of variable stars and transients can be recovered to within ~10arcsec of the M31 nucleus. Our method is simple to implement and is quick enough to be incorporated within real-time DIA pipelines. We also demonstrate that OIS is remarkably robust even when, as in the case of the central regions of the M31 bulge, the sky density of variable sources approaches the confusion limit.

Kerins, E.; Darnley, M. J.; Duke, J. P.; Gould, A.; Han, C.; Newsam, A.; Park, B. G.; Street, R.

2010-11-01

72

Photometry of meteorites  

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

73

Photocells, photomultipliers, and southern-hemisphere photometry.  

NASA Astrophysics Data System (ADS)

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.

Hearnshaw, J. B.

1996-11-01

74

Short-Term Ozone Exposure Affects the Surface Activity of Pulmonary Surfactant  

Microsoft Academic Search

The effects of short-term ozone exposure on the lung function and surface activity of surfactant subtypes isolated from rat lung lavage were studied. Rats were exposed to 0.8 ppm ozone for 2 or 12 hr. The surface activity of surfactant was affected by ozone exposure, whereas distinct morphological changes in bronchoalveolar lavage or in the surfactant subtypes were not observed.

Esther Putman; Willemijn Liese; Wim F. Voorhout; Leendert van Bree; Lambert M. G. van Golde; Henk P. Haagsman

1997-01-01

75

Do leaf surface characteristics affect Agrobacterium infection in tea [ Camellia sinensis (L.) O Kuntze]?  

Microsoft Academic Search

The host range specificity ofAgrobacterium with five tea cultivars and an unrelated species (Artemisia parviflora) having extreme surface characteristics was evaluated in the present study. The degree ofAgrobacterium infection in the five cultivars of tea was affected by leaf wetness, micro-morphology and surface chemistry. Wettable leaf\\u000a surfaces of TV1, Upasi-9 andKangra jat showed higher rate (75%) ofAgrobacterium infection compared to

Nitish Kumar; Subedar Pandey; Amita Bhattacharya; Paramvir Singh Ahuja

2004-01-01

76

Stellar photometry with big pixels  

NASA Astrophysics Data System (ADS)

A new software for stellar photometry in crowded fields is presented. This software overcomes the limitations present in a traditional package like ROMAFOT when the pixel size of the detector is comparable to the scale length of point images. This is the case, for instance, with the Hubble Space Telescope-Wide Field Camera and, partially, with the Planetary Camera. The 'numerical' solution presented here is compared to the 'technical' solution of obtaining more exposures of the same field, each shifted by a fraction of pixel. This software will be available in MIDAS.

Buonanno, Roberto; Iannicola, Giacinto

1989-03-01

77

SPA, "The Stellar Photometry Assistant"  

NASA Astrophysics Data System (ADS)

SPA is a stand alone software package for high speed photometry reduction and analysis. The goal of SPA is to be simple, powerful and intuitive. SPA was born out of complications studying the pulsating DB white dwarf EC20058-5234 (QuTel) due to the proximity of its companions. SPA addresses the Whole Earth Telescope's (Nather et al. 1990) demand for large scale rapid data reduction from multiple sites. SPA is being developed in MATLAB by the Delaware Asteroseismic Research Center (DARC) in collaboration with the University of Delaware and the Mount Cuba Astronomical Observatory.

Dalessio, J.; Provencal, J. L.; Shipman, H. L.

2009-06-01

78

Photometry of astrometric reference stars  

NASA Astrophysics Data System (ADS)

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.

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

1991-12-01

79

NIR photometry of Flaring Blazars from CRTS  

NASA Astrophysics Data System (ADS)

Following the Mahabal, A.A. etal, 2011 report (ATel #3321) of flaring blazars from CRTS, we have carried out NIR photometry of these objects. Over all, the objects are brighter in the H band than previous photometry when available. Our results are summarized below, we list the object ID, the Julian Date of our observations, the H magnitude and a brief comment.

Carrasco, L.; Carraminana, A.; Escobedo, G.; Recillas, E.; Porras, A.; Mayya, D. Y.

2011-05-01

80

UBV photometry in Berkeley 32 (Kaluzny+, 1991)  

NASA Astrophysics Data System (ADS)

The observations were performed at Kitt Peak National Observatory using the 0.9m telescope equipped with the CCD camera of TEK2 chip (512x512pixels, 0.774arcsec/pix). The UBV photometry was obtained in the night of 1989-12-04, and the Washington photometry on the night of 1989-12-11. (1 data file).

Kaluzny, J.; Mazur, B.

2010-08-01

81

Topographical changes of ground surface affected by the shelterbelt along the Tarim Desert Highway  

Microsoft Academic Search

To study the effects of sand protection project on modern aeolian landform, the types, distribution, and intensity of topographical\\u000a changes of the ground surface affected by the shelterbelt along the Tarim Desert Highway were determined by measuring the\\u000a deflation and deposition of sand surface in the Tazhong area located in the hinterland of the Taklimakan Desert. The results\\u000a showed that

ShengYu Li; JiaQiang Lei; XinWen Xu; HaiFeng Wang; JingLong Fan; Feng Gu; YongZhi Qiu; Bo Xu; Qing Gong; Wei Zheng

2008-01-01

82

Theory of wide-angle photometry from standard stars  

NASA Astrophysics Data System (ADS)

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.

Usher, Peter D.

1989-10-01

83

Galaxy photometry at faint light levels - Interaction with the environment  

NASA Astrophysics Data System (ADS)

Interactions of two disk galaxies are considered, taking into account findings which suggest that violent relaxation in the stellar component of a merging system operates on a shorter time scale than dissipation in the gaseous component. Interactions between disk and elliptical galaxies are also discussed along with tidal distension of the envelopes of galaxies, cD galaxies, the halos of spiral galaxies, isophotometry, interacting spiral galaxies, dust lanes, the environment of radio galaxies, and future work. It is pointed out that photometry, particularly panoramic surface photometry, can provide important evidence on the effects of mergers, accretion, and tides on galaxies. More sensitive X-ray telescopes will make it possible to observe the accretion by galaxies of the hot intergalactic medium. Such an accretion is, perhaps, the most important environmental effect on galaxies.

Carter, D.

84

Photometry of a complete sample of faint galaxies  

NASA Astrophysics Data System (ADS)

Techniques are developed for the automatic measurement of the colors and magnitudes of a complete sample of very faint galaxies. The observations consist of photographic surface photometry in two wavebands for approximately 20,000 galaxies in two widely separated, high-latitude fields, each having an area of approximately 1080 sq arcmin. The photometric zero points are derived directly from faint stars in the same fields measured photoelectrically by other observers. The photometry of the galaxy sample is complete to a limit about 10 times fainter than has been systematically investigated before. The sample is characterized by a population of galaxies which becomes bluer with increasing faintness and which increases steeply in number with increasing faintness in the blue waveband.

Kron, R. G.

1980-06-01

85

Early Photometry Studies for Euclid  

NASA Astrophysics Data System (ADS)

The Euclid mission aims to investigate the distance-redshift relationship and the evolution of cosmic structures by measuring shapes and redshifts of galaxies and clusters of galaxies. Data from the satellite instruments will be merged with ground based imaging data from large surveys such as the Dark Energy Survey and Pan-STARRS. Euclid's weak galaxy lensing experiment requires very accurate photometric redshifts and thus precise galaxy colours. In this contribution we compare the ‘traditional approach’ of fitting object models to co-added images with a new technique that simultaneously fits a model to the ensemble of individual images. Preliminary results indicate that the photometry using individual image fitting is more precise.

Kümmel, M.; Koppenhoefer, J.; Riffeser, A.; Mohr, J.; Desai, S.; Henderson, R.; Paech, K.; Wetzstein, M.

2013-10-01

86

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

PubMed

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

Zhang, H; Zhang, X

1994-04-01

87

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

Microsoft Academic Search

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

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

2011-01-01

88

Colloid Surface Chemistry Critically Affects Multiple Particle Tracking Measurements of Biomaterials  

Microsoft Academic Search

Characterization of the properties of complex biomaterials using microrheological techniques has the promise of providing fundamental insights into their biomechanical functions; however, precise interpretations of such measurements are hindered by inadequate characterization of the interactions between tracers and the networks they probe. We here show that colloid surface chemistry can profoundly affect multiple particle tracking measurements of networks of fibrin,

M. T. Valentine; Z. E. Perlman; M. L. Gardel; J. H. Shin; P. Matsudaira; T. J. Mitchison; D. A. Weitz

2004-01-01

89

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

Microsoft Academic Search

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

C. F. Cheung; W. B. Lee

2000-01-01

90

Illinois­—Where Astronomical Photometry Grew Up  

NASA Astrophysics Data System (ADS)

In 1903 Dr. Joel Stebbins joined the University of Illinois faculty as an astronomy instructor and Director of the University of Illinois Observatory. In 1905 he and F. C. Brown began experimenting with selenium sell photometry and developed the equipment and many of the photometric practices used then. Those practices formed the foundation on which present day photometry processes are based. This paper will trace the history of Stebbins’ career and his development of photoelectric photometry from 1903 to 1922. This story explains how Stebbins’ wife, May, caused a change in astronomical observing that continues today.

Beaman, B. B.; Svec, M. T.

2012-06-01

91

Towards understanding how surface life can affect interior geological processes: a non-equilibrium thermodynamics approach  

NASA Astrophysics Data System (ADS)

Life has significantly altered the Earth's atmosphere, oceans and crust. To what extent has it also affected interior geological processes? To address this question, three models of geological processes are formulated: mantle convection, continental crust uplift and erosion and oceanic crust recycling. These processes are characterised as non-equilibrium thermodynamic systems. Their states of disequilibrium are maintained by the power generated from the dissipation of energy from the interior of the Earth. Altering the thickness of continental crust via weathering and erosion affects the upper mantle temperature which leads to changes in rates of oceanic crust recycling and consequently rates of outgassing of carbon dioxide into the atmosphere. Estimates for the power generated by various elements in the Earth system are shown. This includes, inter alia, surface life generation of 264 TW of power, much greater than those of geological processes such as mantle convection at 12 TW. This high power results from life's ability to harvest energy directly from the sun. Life need only utilise a small fraction of the generated free chemical energy for geochemical transformations at the surface, such as affecting rates of weathering and erosion of continental rocks, in order to affect interior, geological processes. Consequently when assessing the effects of life on Earth, and potentially any planet with a significant biosphere, dynamical models may be required that better capture the coupled nature of biologically-mediated surface and interior processes.

Dyke, J. G.; Gans, F.; Kleidon, A.

2011-06-01

92

NICMOS Photometry of High Redshift Supernovae  

NASA Astrophysics Data System (ADS)

Type Ia supernovae have emerged as excellent cosmological tools. Near infrared photometry becomes increasingly important as observations are pushed to higher redshifts. In particular, near-IR observations can be used to estimate reddening and assess systematic effects such as grey dust. We present infrared photometry of five supernovae obtained using the NICMOS detector on HST. The observed supernovae range in redshift from 0.35 to 0.86. The low background in these images provides more precise photometry than is possible from the ground and the higher resolution allows for a more reliable estimate of host galaxy contamination. We will present data reduction techniques, cosmological implications, and summarize the difficulties of doing absolute photometry using NICMOS. This research is supported by the Department of Energy and by the NASA Space Telescope Science Institute.

Burns, M. S.; Aldering, G.; Amanullah, R.; Antilogus, P.; Astier, P.; Balland, C.; Blanc, G.; Conley, A.; Deustua, S.; Ellis, R.; Fabbro, S.; Folatelli, G.; Fruchter, A.; Garavini, G.; Gibbons, R.; Goldhaber, G.; Goobar, A.; Groom, D. E.; Hardin, D.; Hook, I. M.; Howell, D. A.; Irwin, M.; Kasen, D.; Kim, A.; Knop, R. A.; Levy, J.-M.; Lidman, C.; McMahon, R.; Mouchet, M.; Nobili, S.; Nugent, P.; Pain, R.; Panagia, N.; Pécontal, E.; Pennypacker, C. R.; Perlmutter, S.; Quimby, R.; Raux, J.; Regnault, N.; Ruiz-Lapuente, P.; Schaefer, B.; Schahmaneche, K.; Spadafora, A. L.; Walton, N.; Wang, L.; Wood-Vasey, W. M.; Supernova Cosmology Project Collaboration

2001-12-01

93

CCD Photometry of UW Coronae Borealis  

Microsoft Academic Search

We present CCD photometry of the low mass X-ray binary UW CrB (MS1603+260) using the McDonald Observatory 107in telescope. These data were obtained on 20 nights during 2002, 2003, and 2004. Hynes, Robinson, and Jeffery (2004) found that UW CrB contains a neutron star exhibiting optical reprocessing of type I X-ray bursts. CCD photometry from that study is included in

Paul A. Mason; E. L. Robinson; C. L. Gray

2006-01-01

94

UBVRI photometry in NGC6791 (Brogaard+, 2012)  

NASA Astrophysics Data System (ADS)

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).

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

95

Synthetic IR Photometry of Main Sequence Stars  

NASA Astrophysics Data System (ADS)

We describe results on the calculation and comparison of synthetic photometry in 40 IR and sub-mm bands conducted using three different libraries of theoretical stellar spectra: MARCS, ATLAS9 and PHOENIX. Discrepancies of photometric magnitudes obtained with these libraries are less than 3% over the wavelength range 1-160?m. We use PHOENIX fluxes to construct an extensive grid of nearly 9000 points that cover the effective temperature interval 5000-7000 K (step of 200 K), surface gravity, log(g) = 3.5 to 5.0 (step of 0.5 dex), and [M/H] = -2.0 to +0.0 (step of 0.5 dex). We use PHOENIX theoretical fluxes and simple disk emission models to construct a series of diagnostic diagrams that allow a direct identification of an IR-submm excess and a preliminary determination of the properties of the material originating that excess. The grid is aimed at providing a handy access to photospheric fluxes for the analysis of IR excesses of solar like stars.

Cruz Saenz de Miera, F.; Chavez, M.; Bertone, E.; Vega, O.

2013-04-01

96

Development and characterization of integrating sphere for photometry and radiometry measurement  

NASA Astrophysics Data System (ADS)

Integrating Sphere (IS) is an instrument formed a cavity sphere with its inner surface act as a Lambertian reflector. IS is needed in many optical measurements which involves a high diffused reflection. In addition, IS very essential in photometry and radiometry measurement system. However, currently, IS is still an imported product which considered very expensive. The material for the sphere and inner surface coating affect the performance of the IS systems. Therefore, the main challenges in designing IS are the material engineering for the sphere and the procedure for the inner surface coating. The inner surface was coated using BaSO4 which has a low absorption and high diffuse reflection. Spectral responses of the IS system was characterized using USB2000+ and calibrated using a standard Spectralon from ocean optic. The obtained IS system used an inner surface coating from a mixed 80% Barium Sulfate (BaSO4) and 20% Nippon Elastex paint which yield a reflection factor ? = 0.955 and amplification factor M=10.69. The validation was conducted using an emitter with known specification from Luxeon of LXHL-DW01 which produced light flux 40.5 lumen with injection current 350 mA and junction temperature Tj 25°C.

Wibawa, Bambang Mukti; Mujahid, Abdul Al; Mindara, Jajat Yuda; Panatarani, Camellia; Joni, I. Made; Siregar, Rustam Efendi

2013-09-01

97

Scaffold's surface geometry significantly affects human stem cell bone tissue engineering.  

PubMed

In this study, we have observed dental pulp stem cells (SBP-DPSCs) performances on different scaffolds, such as PLGA 85:15, hydroxyapatite chips (HA) and titanium. Stem cells were challenged with each engineered surface, either in plane cultures or in a rotating apparatus, for a month. Gingival fibroblasts were used as controls. Results showed that stem cells exerted a different response, depending on the different type of textured surface: in fact, microconcavities significantly affected SBP-DPSC differentiation into osteoblasts, both temporally and quantitatively, with respect to the other textured surfaces. Actually, stem cells challenged with concave surfaces differentiated quicker and showed nuclear polarity, an index of secretion, cellular activity and matrix formation. Moreover, bone-specific proteins were significantly expressed and the obtained bone tissue was of significant thickness. Thus, cells cultured on the concave textured surface had better cell-scaffold interactions and were induced to secrete factors that, due to their autocrine effects, quickly lead to osteodifferentiation, bone tissue formation, and vascularization. The worst cell performance was obtained using convex surfaces, due to the scarce cell proliferation on to the scaffold and the poor matrix secretion. In conclusion, this study stresses that for a suitable and successful bone tissue reconstruction the surface texture is of paramount importance. PMID:17565721

Graziano, Antonio; d'Aquino, Riccardo; Cusella-De Angelis, Maria Gabriella; De Francesco, Francesco; Giordano, Antonio; Laino, Gregorio; Piattelli, Adriano; Traini, Tonino; De Rosa, Alfredo; Papaccio, Gianpaolo

2008-01-01

98

Multicolor Photometry for Mode Identification  

NASA Astrophysics Data System (ADS)

The goal of asteroseismology is to discern the physical conditions of stars by comparing observed pulsations with models. To obtain this goal, the observed pulsation periods and the spherical harmonics (n, l, and m) need to match the theoretical model. Typically the most difficult part in this process is the identification of the pulsation modes in the observations. Multicolour photometry is one method that has proven useful for identifying pulsation modes. By observing stars through various wavebands, and comparing the amplitudes and phases, it is possible to determine the spherical harmonics. This contribution will emphasize the work of Watson (1988), which has since been applied to many different types of variable stars including ? Scuti (Garrido et al., 1990), ? Doradus (Breger et al., 1997), ? Cepheid (Cugier et al., 1994), and EC 14026 (Koen, 1998) stars. I will also discuss the technique of summing spectra (especially UV) into various wavebands which are then used to identify modes as pioneered by Robinson, Kepler, and Nather (1982) and applied to white dwarf stars (Kepler et al., 2000).

Reed, M. D.

99

Surface seal micromorphology as affected by fluidized bed combustion bottom-ash  

Microsoft Academic Search

Amendments that alter clay dispersion and aggregate disintegration also change soil porosity and sealing. Soils selected for this study had increased (Mollisol, Oxisol, and Vertisol), decreased (Oxisol), or non-affected (Oxisol and Ultisol) water infiltration when fluidized bed combustor bottom-ash (FBCBA) was surface applied to decrease dispersion. Soil was sieved to pass 8-mm, packed into small erosion pans, prewetted by capillarity,

J. M. Reichert; L. D. Norton

1995-01-01

100

Probing Photometry of the Irregular Outer Planets Satellites for Evidence of Aqueous Alteration  

NASA Astrophysics Data System (ADS)

The faint, irregular outer planet satellites are hypothesized to be fragments of larger parent bodies disrupted by collisional impacts and captured in their present locations. Their faintness limits spectroscopic observations, so we need other methods of constraining their surface compositions. Visible reflectance spectra of many main-belt and outer-belt low-albedo asteroids show the presence of an absorption feature centered near 0.7 um attributed to a ferrous-ferric charge transfer transition in oxidized iron in phyllosilicates. This feature is highly correlated with the 3.0-um water of hydration absorption feature, suggesting that aqueous alteration operated on the surfaces of these asteroids. We searched for evidence of aqueous alteration in BVRI photometry obtained in 2001-2 of 21 irregular Jovian and Saturnian satellites by Grav et al. (Icarus 166, 2003). We converted the V-R and V-I colors to ECAS v-w and v-x colors by inverting formulae determined by E. Howell (Ph.D. Thesis, U. Arizona, 1995). We then applied Vilas' formula (Icarus 111, 1994) for identifying the presence of this 0.7-um feature in ECAS photometry. Evidence for the presence of the 0.7-um absorption feature is found in photometry of Jovian irregular satellites in all of the inclination clusters, often mixed with satellites having photometry not showing this feature. The presence of the 0.7-um feature does not necessarily correlate with the grey/light red division of photometry offered by Grav et al. No evidence for the feature is seen in this photometry of the Saturnian irregular satellites, including Phoebe. As a proof of concept, we obtained UBVRI photometry of Ch-class asteroid 19 Fortuna using the Swope 1.0-m telescope at Las Campanas Observatory in June 2004; the absorption feature is easily identified. Analyses of results will be presented. SML and SLG thank the NASA MUCERPI program. Everyone thanks LCO OCIW.

Vilas, F.; Lederer, S. M.; Gill, S. L.; Thomas-Osip, J. E.; Osip, D. J.

2004-11-01

101

Surface chemical functionalities affect the behavior of human adipose-derived stem cells in vitro  

NASA Astrophysics Data System (ADS)

This study examines the effect of surface chemical functionalities on the behavior of human adipose-derived stem cells (hASCs) in vitro. Plasma polymerized films rich in amine (NH2), carboxyl (COOH) and methyl (CH3), were generated on hydroxyapatite (HAp) substrates. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy (XPS). The ability of different substrates to absorb proteins was evaluated. The results showed that substrates modified with hydrophilic functional group (COOH and NH2) can absorb more proteins than these modified with more hydrophobic functional group (CH3). The behavior of human adipose-derived stem cells (hASCs) cultured on different substrates was investigated in vitro: cell counting kit-8 (CCK-8) analysis was used to characterize cell proliferation, scanning electronic microscopy (SEM) analysis was used to characterize cell morphology and alkaline phosphatase (ALP) activity analysis was used to account for differentiation. The results of this study demonstrated that the NH2 modified surfaces encourage osteogenic differentiation; the COOH modified surfaces promote cell adhesion and spreading and the CH3 modified surfaces have the lowest ability to induce osteogenic differentiation. These findings confirmed that the surface chemical states of biomaterials can affect the behavior of hASCs in vitro.

Liu, Xujie; Feng, Qingling; Bachhuka, Akash; Vasilev, Krasimir

2013-04-01

102

Differential Photometry at 1612 MHz  

NASA Astrophysics Data System (ADS)

The 1612 MHz light curves of high latitude OH/IR stars have been observed for several years with the Arecibo 305m telescope, to derive the light-travel time diameter of their shells from the phase difference between their red and blue shifted peaks, and to look for secular evolution of their masers. However, direct intensity measurements are always limited by the extent to which the telescope's characteristics can be removed. These, in Arecibo's case, are subject to changes in the weight distribution about the structure over time, to the functioning of the vertical tie-down system, which can be interrupted by thunder storms, and by temperature-related zenith angle effects during daytime observations. Nevertheless, all of these limitations are neutralized when the ratio of the two peaks is used as the observed parameter. This form of differential photometry often results in clean light curves, though the ratio may still be perturbed by RFI, by interstellar scintillation, and more predictably by noise. The increased sensitivity of this observing mode readily detects (1) any differential evolution of the two masers, as well as (2) highlighting changes in masing gain between the two peaks around the pulsation cycle, that in turn are indicative of the operation of partially rather than fully saturated masers. In many of our light-curves there are abrupt changes in the ratio of the peak intensities at a constant pulsation phase. These are interpreted as being due to the onset of dust formation at that phase of the pulsation cycle, with a consequent abrupt change in the reprocessing of the stellar SED, and hence to an abrupt change in the maser pump. This is a feature of the Gray, Howe & Lewis (MN 364, 783 (2005)) maser model. Examples of these effects will be shown.

Lewis, B. Murray

2009-01-01

103

Improved Photometry for the DASCH Pipeline  

NASA Astrophysics Data System (ADS)

The Digital Access to a Sky Century@Harvard (DASCH) project is digitizing the ˜500,000 glass plate images obtained (full sky) by the Harvard College Observatory from 1885 to 1992. Astrometry and photometry for each resolved object are derived with photometric rms values of ˜0.15 mag for the initial photometry analysis pipeline. Here we describe new developments for DASCH photometry, applied to the Kepler field, that have yielded further improvements, including better identification of image blends and plate defects by measuring image profiles and astrometric deviations. A local calibration procedure using nearby stars in a similar magnitude range as the program star (similar to what has been done for visual photometry from the plates) yields additional improvement for a net photometric rms of ˜0.1 mag. We also describe statistical measures of light curves that are now used in the DASCH pipeline processing to identify new variables autonomously. The DASCH photometry methods described here are used in the pipeline processing for the data releases of DASCH data,5 as well as for a forthcoming paper on the long-term variables discovered by DASCH in the Kepler field.

Tang, Sumin; Grindlay, Jonathan; Los, Edward; Servillat, Mathieu

2013-07-01

104

Photometry Studies of Asteroids and Variable Stars  

NASA Astrophysics Data System (ADS)

During the fall semester of 2012, we carried out extensive photometry studies of asteroids to obtain their rotation periods using the 0.9-m SARA North telescope located at the Kitt Peak National Observatory in Arizona and at the 0.6-m SARA South telescope located at the Cerro Tololo Inter-American Observatory in Chile. The asteroids that we carried out photometry studies include: 782 Montefiore, 3024 Hainan, 3842 Harlansmith, 3920 Aubignan, 5542 Moffatt, 5951 AliceMone, 6720 Gifu, 19978 1989VJ. We will present their rotation periods, and compare with previous results where available. During the course of photometry studies, we also discovered several variable stars. We will also present these new variable stars and their periods.

Han, Xianming; Li, B.; Zhao, H.; Liu, W.; Sun, L.; Gao, S.; Shi, J.; Wang, S.; Pan, X.; Jiang, P.; Zhou, H.

2013-01-01

105

An Improved Method for Differential Photometry  

NASA Astrophysics Data System (ADS)

We developed a method to improve the conventional differential photometry by using many auxiliary stars to reduce noise in the reference light curve, which is used to calibrate the light curve of the target star. The data used in this study are taken with the Taiwan Automated Telescope network. The light curves of two ? Scuti, HD 163032 and V830 Her, are shown here as examples. The results are compared with four other methods: conventional differential photometry; ensemble photometry; the method of Tamuz, Mazeh, & Zucker; and trend filtering algorithm. The light curve computed with our method is smoother than the other four methods, while preserving the pulsational signals. The mode frequencies determined from the light curve from our method also has a higher S/N and lower error in comparison with other methods.

Fernández Fernández, Javier; Chou, Dean-Yi; Pan, Yen-Chen; Wang, Li-Hang

2012-05-01

106

UBVJHKLM photometry of Nova Del 2013  

NASA Astrophysics Data System (ADS)

We present the results of the optical and IR photometry of Nova Del 2013 obtained at the Crimean Station (Nauchny, Ukraine) of the Sternberg Astronomical Institute. UBV photometry was carried out with 60-cm Zeiss telescope using a photoelectric photometer on August 15.94 UT: U=4.54+/-0.02, B=5.07+/-0.01, V=5.05+/-0.01; on August 16.80 UT: U=4.54+/-0.01, B=4.85+/-0.02, V=4.68+/-0.01; on August 16.86 UT: U=4.66+/-0.01, B=4.92+/-0.01, V=4.73+/-0.01.

Burlak, A. M.; Shenavrin, I. V.; Tatarnikov, M. A.; Tatarnikova, A. A.

2013-08-01

107

Optimized Structure and Vibrational Properties by Error Affected Potential Energy Surfaces  

PubMed Central

The precise theoretical determination of the geometrical parameters of molecules at the minima of their potential energy surface and of the corresponding vibrational properties are of fundamental importance for the interpretation of vibrational spectroscopy experiments. Quantum Monte Carlo techniques are correlated electronic structure methods promising for large molecules, which are intrinsically affected by stochastic errors on both energy and force calculations, making the mentioned calculations more challenging with respect to other more traditional quantum chemistry tools. To circumvent this drawback in the present work, we formulate the general problem of evaluating the molecular equilibrium structures, the harmonic frequencies, and the anharmonic coefficients of an error affected potential energy surface. The proposed approach, based on a multidimensional fitting procedure, is illustrated together with a critical evaluation of systematic and statistical errors. We observe that the use of forces instead of energies in the fitting procedure reduces the statistical uncertainty of the vibrational parameters by 1 order of magnitude. Preliminary results based on variational Monte Carlo calculations on the water molecule demonstrate the possibility to evaluate geometrical parameters and harmonic and anharmonic coefficients at this level of theory with an affordable computational cost and a small stochastic uncertainty (<0.07% for geometries and <0.7% for vibrational properties).

Zen, Andrea; Zhelyazov, Delyan; Guidoni, Leonardo

2013-01-01

108

Sinusoidal variables from the Tycho Epoch Photometry Annex  

Microsoft Academic Search

The Tycho Epoch Photometry Annex A, a data base of photometry of more than 34 000 bright stars, has been searched for periodic variable stars with approximately sinusoidal light curves. Advantage was taken of special properties of the observing programme (photometry in two wavebands, availability of repeated measurements) to use simple but efficient variable selection criteria. Details of 70 strong

Chris Koen; Robert Schumann

1999-01-01

109

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

110

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

SciTech Connect

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.

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

111

Photometry of Venus from Mariner 10  

Microsoft Academic Search

Photometry of the upper atmosphere of Venus from Mariner 10 on February 5, 1974 is discussed with respect to in-flight verification of camera linearity, shading, and absolute photometric calibration. Among photometric results are the following: (1) temporal brightness variations were observed in the UV greater than 10% over a few hours due to the rapid rotation of the upper atmosphere,

Bruce Hapke

1976-01-01

112

Walraven photometry of nearby southern OB associations  

NASA Astrophysics Data System (ADS)

Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars in the regions of five nearby southern OB associations: Scorpio Centaurus (Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2. Derived V and (B - V) in the Johnson system are included.

de Geus, E. J.; Lub, J.; van de Grift, E.

1990-10-01

113

Astronomical Photoelectric Photometry for Undergraduate Research  

Microsoft Academic Search

Many college physics departments would welcome the opportunity to initiate a modest research program which could involve their undergraduate students. Astronomical photoelectric photometry is a field in which it is possible to initiate a useful undergraduate oriented research program with relatively modest equipment, some of which can commonly be found in a college physics department. A sketch of the equipment

Albert D. Grauer

1974-01-01

114

Wise Observatory System of Fast CCD Photometry  

NASA Astrophysics Data System (ADS)

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.

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

115

General Photometry of Galaxies (Prugniel+ 1998)  

NASA Astrophysics Data System (ADS)

The tables presented here give the catalogue of aperture photometry of galaxies (UBVRI), the associated bibliography, the weight and systematic corrections applied to individual datasets. A table give the results of the growth curve fits; the net of curves adopted is a linear interpolation between the de Vaucouleurs (r1/4) and exponential laws. This aperture photometry has three different origins: (i) an update of the catalogue of Buta et al. 1995 (Cat. ) (ii) published photometric profiles and (iii) aperture photometry performed on CCD images. Fitting growth curves to aperture photometry of galaxies, in UBVRI, we derive (1) the total magnitude, (2) the effective radius, (3) the color indices and (4) gradients and (5) the photometric type of 5066 galaxies. The photometric type is defined to statistically match the revised morphologic type (numerically coded from -6 to +10) and represents the shape of the growth curve. The catalogue is maintained up-to-date in the database HYPERCAT (http://www-obs.univ-lyon1.fr/~prugniel/cgi-bin/hypercat/). This catalogue supersedes the Longo and de Vaucouleurs (1983) catalogue . (4 data files).

Prugniel, P.; Heraudeau, P.

1998-03-01

116

Elucidating Sources and Factors Affecting Delivery of Nitrogen to Surface Waters of New York State  

NASA Astrophysics Data System (ADS)

Rapid changes in power generation, transportation, and agriculture have appreciably altered nitrogen (N) cycling at regional scales, increasing N inputs to landscapes and surface waters. Numerous studies have linked this surplus N to a host of concerns, including eutrophication and violations in drinking water standards. Inputs of N nation-wide have increased during recent decades, primarily from the production and use of fertilizers, the planting of N-fixing crops, and the combustion of fossil fuels. The role of atmospheric N sources is of particular concern in New York, as rates of atmospheric N deposition in the northeast are among the highest in the nation. Our work aims to quantify nitrogen sources and fate in watersheds throughout the state. Further, we intend to elucidate factors controlling the retention and release of N to surface waters. We quantify nitrogen inputs through both measurement data (e.g., from wet and dry atmospheric deposition, precipitation, streamflow, water quality, and isotopic tracers) and from synoptic spatial databases (e.g., of terrain, land use, and fertilizer inputs). We present preliminary results from large catchments in contrasting spatial settings across the state (different land use configurations and atmospheric deposition gradients), illustrating the contribution of nitrogen sources to each region and factors affecting delivery to surface waters. Further, we present 30 years of temporal data from a large watershed (Fall Creek) in the Finger Lakes region of the state to demonstrate how hydrological and biogeochemical factors, over seasons and under varying hydrological regimes, combine to control N dynamics in surface waters. Our collective work provides information that is necessary to develop sound strategies for understanding and managing nutrients at regional scales.

Golden, H. E.; Boyer, E. W.; Burns, D. A.; Elliott, E.; Kendall, C.; Butler, T.

2005-12-01

117

Affected zone generated around the erosion pit on carbon steel surface at the incipient stage of vibration cavitation  

Microsoft Academic Search

The characteristics of erosion pits on a carbon steel surface were investigated at the incipient stage of cavitation erosion.\\u000a After a 5-minute experiment performed in an ultrasonic vibration system, needle-like erosion pits appeared on the polished\\u000a steel surface, and a specially affected zone was formed around the pit. The shape of the pit and the plastic deformation of\\u000a the affected

HaoSheng Chen; Jiang Li; ShiHan Liu; DaRong Chen; JiaDao Wang

2008-01-01

118

Factors affecting use of CR-39 surface monitor technology to estimate past exposure to indoor radon.  

PubMed

In an epidemiologic study investigating influences of life-style and environment on lung cancer risk, CR-39 alpha-particle detectors, identified here as surface monitors, were affixed to subjects' selected household glass, ceramic, or enameled objects to measure residual radioactivity form embedded radon (Rn) decay products. The purpose was to estimate past cumulative indoor Rn concentrations to which the object was exposed to infer past exposures of the subjects. This approach was used to supplement exposure information obtained by methods traditionally used in Rn epidemiologic studies. In addition, surface monitors were affixed to objects of selected study subjects with complete exposure information to evaluate whether surface monitors provided estimates of cumulative past residual Rn exposure comparable to estimates obtained from year-long, ambient alpha track-etch measurements in each present and previous residence. These ambient measurements were time-weighted to estimate integrated exposure of objects and were adjusted for decay and ingrowth so as to be comparable to surface monitor measurements. A regression relationship was estimated between the two estimates of cumulative RN exposure. Surface monitor measurements had a satisfactory correlation (0.63) with adjusted ambient Rn measurements for new, nonceramic objects. Although not included in the study design, factors that might affect use of the technology were also investigated. Regression relationships were compared in graduated smoking environment (as judged by the subjects) to investigate possible differential plate out of radon progeny. In addition, regression relationships for windows were compared with those for other objects to investigate whether there was a significant difference between windows and other objects. It has been suggested that windows may have a higher plate out rate because of locally increased air flow. Results suggested that surface monitor information was useful to fill time gaps in estimates of historical radon exposure data obtained by ambient measurements. Glass samples provided the best correlation. Ceramic materials sometimes provided excessively high radon estimates, probably due to glazes that contained significant uranium or thorium. Due to small sample sizes, investigations of other factors were inconclusive. PMID:9087863

Mahaffey, J A; Parkhurst, M A; Hui, T E; Brownson, R C; Alavanja, M C

119

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

SciTech Connect

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.

Norland, M.R.

1993-01-01

120

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

SciTech Connect

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.

Epstein, L.M.; Forney, J.D.

1984-08-01

121

Command surfaces 12 [1]. Factors affecting in-plane photoregulation of liquid crystal alignment by surface azobenzenes on a silica substrate  

Microsoft Academic Search

In-plane alignment of nematic liquid crystals was regulated by polarized-light-irradiation of a cell assembled with a silica plate, the surface of which was modified by attaching 4-hexyl-4?-hexyloxyazobenzene at its o-position through surface silylation. The photoisomerizability of the chemisorbed azo-chromophore was affected by their surface density and the nature of photoinactive co-modifiers. The efficiency of the photoregulation of liquid crystal alignment

Kunihioro Ichimura; Haruhisa Akiyama; Kazuaki Kudo; Norio Ishizuki; Shigeo Yamamura

1996-01-01

122

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

PubMed

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

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

2006-03-03

123

Parameters affecting spore recovery from wipes used in biological surface sampling.  

PubMed

The need for the precise and reliable collection of potential biothreat contaminants has motivated research in developing a better understanding of the variability in biological surface sampling methods. In this context, the objective of this work was to determine parameters affecting the efficiency of extracting Bacillus anthracis Sterne spores from commonly used wipe sampling materials and to describe performance using the interfacial energy concept. In addition, surface thermodynamics was applied to understand and predict surface sampling performance. Wipe materials were directly inoculated with known concentrations of B. anthracis spores and placed into extraction solutions, followed by sonication or vortexing. Experimental factors investigated included wipe material (polyester, cotton, and polyester-rayon), extraction solution (sterile deionized water [H(2)O], deionized water with 0.04% Tween 80 [H(2)O-T], phosphate-buffered saline [PBS], and PBS with 0.04% Tween 80 [PBST]), and physical dissociation method (vortexing or sonication). The most efficient extraction from wipes was observed for solutions containing the nonionic surfactant Tween 80. The increase in extraction efficiency due to surfactant addition was attributed to an attractive interfacial energy between Tween 80 and the centrifuge tube wall, which prevented spore adhesion. Extraction solution significantly impacted the extraction efficiency, as determined by statistical analysis (P < 0.05). Moreover, the extraction solution was the most important factor in extraction performance, followed by the wipe material. Polyester-rayon was the most efficient wipe material for releasing spores into solution by rank; however, no statistically significant difference between polyester-rayon and cotton was observed (P > 0.05). Vortexing provided higher spore recovery in H(2)O and H(2)O-T than sonication, when all three wipe materials and the reference control were considered (P < 0.05). PMID:21296945

Da Silva, Sandra M; Filliben, James J; Morrow, Jayne B

2011-02-04

124

Photometry of faint blue stars - IX  

NASA Astrophysics Data System (ADS)

Stromgren uv by photometry is presented for 129 `faint blue' stars taken from various catalogues. The photometry is used to estimate photometric `classifications' for the stars, which indicate a mixture of hot subdwarfs, horizontal-branch stars, metal-weak subdwarfs and so on. Attention is drawn to stars (from this paper and previous papers in the series) which appear to be somewhat reddened. Some are probably binaries, and others might be objects with peculiar colours, such as cataclysmic variables. One star, LB 9963, almost certainly falls into the latter category. Two stars which, from their colours, are Population II A-F stars are variable; one of these, OM 89, is the known RR Lyrae star, VW Dor.

Kilkenny, D.

1995-12-01

125

Photometry of Variables from Dome A, Antarctica  

NASA Astrophysics Data System (ADS)

Dome A on the Antarctic plateau is likely one of the best observing sites on Earth (Saunders et al. 2009). We used the CSTAR telescope (Yuan et al. 2008) to obtain time-series photometry of 104 stars with i>14.5 mag during 128 days of the 2008 Antarctic winter season (Wang et al. 2011). During the 2010 season we observed 2 × 104 stars with i>15 mag for 183 days (Wang et al. 2012). We detected a total of 262 variables, a 6 × increase relative to previous surveys of the same area and depth carried out from temperate sites (Pojmanski 2004). Our observations show that high-precision, long-term photometry is possible from Antarctica and that astronomically useful data can be obtained during 80% of the winter season.

Wang, Lingzhi; Macri, L. M.; Wang, L.; Ashley, M. C. B.; Cui, X.; Feng, L. L.; Gong, X.; Lawrence, J. S.; Liu, Q.; Luong-Van, D.; Pennypacker, C. R.; Shang, Z.; Storey, J. W. V.; Yang, H.; Yang, J.; Yuan, X.; York, D. G.; Zhou, X.; Zhu, Z.; Zhu, Z.

2013-01-01

126

Distant galaxy clusters photometry (Stanford+, 2002)  

NASA Astrophysics Data System (ADS)

We present optical and near-infrared photometry of 45 clusters of galaxies at 0.1photometry has been used in previously published papers to examine the origin and evolution of galaxies in distant clusters. Beginning in 1991, we sought to make use of the advent of relatively large format near-IR detectors to study the galaxy populations of distant clusters. We collected imaging data in both the near-IR and the optical on a large sample of clusters drawn from several samples. These data were analyzed and detailed results were presented on the evolution of early-type galaxies at moderate redshifts in Stanford, Eisenhardt, & Dickinson (1995ApJ...450..512S, 1998ApJ...492..461S), on the evolution of the K-band luminosity function in De Propris et al. (1999AJ....118..719D), on the Butcher-Oemler effect in K-selected galaxy samples in De Propris et al. (2003, ApJ, submitted), and on the evolution of early-type galaxies in high-redshift clusters in Holden et al. (2003, ApJ, in press). So far the photometry for these various studies has been published for only two clusters, Abell 370 and Abell 851 in Stanford et al. (1995ApJ...450..512S). In this paper, we present the photometry on the other 43 clusters used in our published work on distant clusters. (9 data files).

Stanford, S. A.; Eisenhardt, P. R.; Dickinson, M.; Holden, B. P.; de Propris, R.

2002-11-01

127

UBVRIJHK photometry in NGC1624 (Jose+, 2011)  

NASA Astrophysics Data System (ADS)

The CCD UBVRI observations of NGC 1624 were carried out using Hanle Faint Object Spectrograph and Camera (HFOSC) of the 2-m Himalayan Chandra Telescope (HCT) of Indian Astronomical Observatory (IAO), Hanle, India on 2004 November 3. We repeated the observations of NGC 1624 in V and Ic filters to get a deeper photometry on 2006 December 12 using the 104-cm Sampurnanand Telescope (ST) of Aryabhatta Research Institute of observational sciencES (ARIES), Naini Tal, India. (1 data file).

Jose, J.; Pandey, A. K.; Ogura, K.; Ojha, D. K.; Bhatt, B. C.; Samal, M. R.; Chauhan, N.; Sahu, D. K.; Rawat, P. S.

2011-10-01

128

Current Integrator for Astronomical Photoelectric Photometry  

Microsoft Academic Search

An integrator circuit is described, together with programmer and timer, which was constructed for measuring signal-current from a photomultiplier tube as used in astronomical photometry. At the end of a timed run, the voltage data are impressed upon a strip-chart pen recorder. The current-range of such instrument encompasses a span from 10?6 to 10?11 ampere, full scale, with stability and

Robert H. Weitbrecht

1957-01-01

129

Galileo Photometry of Asteroid 951 Gaspra  

USGS Publications Warehouse

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.

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

130

100 years of photometry and radiometry  

NASA Astrophysics Data System (ADS)

Measurement of light is an old subject, though the past 100 years have seen significant advances. 100 years ago, photometry - the art and science of measuring light as it is perceived by people - had the greater technological importance. Even today SI (the metric system) retains a base unit for photometry, the candela. However, early work at NBS included pivotal projects in the field of radiometry - the measurement of the physical characteristics of light. These included the validation of Planck's newly-minted theory of blackbody radiation, determining the radiation constants with good accuracy, and the definitive analysis of the spectral responsivity of human vision, so as to relate photometry to radiometry. This latter work has only increased in importance over the past 75 years as the definition of the candela has changed and improved. Today, NIST makes radiometric, and hence photometric measurements, with unprecedented precision. Cryogenic radiometers based on the principle of electrical substitution measure optical flux with uncertainties of 0.02%. Additional facilities enable measurement of spectral responsivity, spectral radiance, and spectral irradiance. Novel detectors, such as light-traps, allow the best accuracy to be transferred from the primary standards to routinely-used instruments and to calibration customers. Filtered detectors are used to realize photometric scales, radiation temperature scales, and other specialized measurements. Indeed, the story of the metrology of light is the story of continuous improvement, both driven by and enabled by advances in technology. We touch upon some of these as a prelude to the other talks in this Conference.

Hardis, Jonathan E.

2001-06-01

131

Astrometry and photometry in high contrast imaging  

NASA Astrophysics Data System (ADS)

The direct exoplanet imaging field will strongly benefit from the larger aperture and the higher angular resolution achieved by next generation 30+m telescopes. To fully take advantage of these new facilities, one of the biggest challenges that ground-based adaptive optics imaging must overcome is to be able to derive accurate astrometry and photometry with realistic estimate of residual errors. The planet photometry and its astrometry are used to compare with atmospheric models and to fit orbits. If erroneous numbers are found, or if errors are underestimated, spurious fits can lead to unphysical planet characteristics or wrong/unstable orbits. Overestimating the errors also needs to be avoided as it degrades the value of the data. In the high-contrast planet imaging context, we will present various photometry/astrometry biases induced by several noise sources (anisoplanatism, non-Gaussian noise, etc.) or processing techniques (ADI/SSDI/LOCI) that we have uncovered during our ongoing direct exoplanet imaging campaign at Gemini, VLT and Keck. We will describe the procedures that we have implemented to properly estimate those biases. These solutions will be implemented in the Gemini Planet Imager campaign data pipeline and we expect that they will also play a crucial role in any future 30+m survey.

Galicher, Raphael; Marois, Christian

2011-09-01

132

Differential Photometry with OSCAAR: Open Source Differential Photometry Code for Amateur Astronomical Research  

NASA Astrophysics Data System (ADS)

We present a cross-platform, open-source differential photometry package written in Python, called OSCAAR (Open Source differential photometry Code for Amateur Astronomical Research). The code is intended for use by undergraduate students or small observatories, or to be used as a scaffolding to be built upon and refined by more advanced users. OSCAAR can be controlled with a graphical user interface for those unfamiliar with Python. OSCAAR makes extensive use of existing astronomical software packages, and the implementation of classes and methods within OSCAAR is designed to be highly modular and interchangeable. The aim of OSCAAR is to provide a free, practical differential photometry toolkit with which users can easily create light curves, and also to encourage the users to work with the source code and refine it for their own purposes.

Morris, Brett M.; Katz, H.; OSCAAR Team

2013-06-01

133

Photometry of UCM galaxies. II. (Perez-Gonzalez+, 2001)  

NASA Astrophysics Data System (ADS)

We present Johnson B surface photometry for the UCM Survey galaxies. One-dimensional bulge-disk decomposition is attempted, discussing on fitting functions and computational procedures. The results from this decomposition, jointly with concentration indices and an asymmetry coefficient, are employed to study the morphological properties of these galaxies. We also compare our results with the previous morphological classification established using Gunn r imaging data and with other samples of galaxies. No major statistical differences in morphology are found between red and blue data, although some characteristics such as size and luminosity concentration vary. We find a correlation between luminosity and size. Several parameters are used to segregate the objects according to their morphological type. (2 data files).

Perez-Gonzalez, P. G.; Gallego, J.; Zamorano, J.; Gil de Paz, A.

2000-11-01

134

New UBVRI Photometry of 234 M33 Star Clusters  

NASA Astrophysics Data System (ADS)

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 deg2 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 & Kaluzny. Combined with star cluster photometry in previous studies, we present some results: none of the M33 youngest clusters (~107 yr) have masses approaching 105 M ?, 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.

Ma, Jun

2013-04-01

135

Investigating Correlations between Photometry and Morphology of Spiral Galaxies  

NASA Astrophysics Data System (ADS)

Early in extragalactic astronomy it was noticed that spiral galaxies have the same central optical surface brightness. Freeman (1970) quantified this property of spirals, finding the average B-band surface brighness value to be 21.65 mag/arcsec(2) with a remarkably small scatter of 0.3 mag/arcsec(2) . The reason for this "universal" surface brightness value is difficult to explain physically, given that Hubble morphological sequence represents galaxies with different kinematic, structural and starforming properties. Our study determines whether or not the constant surface brightness trend holds for normal, high surface brightness galaxies at infrared wavelengths, where a different (older) component of the stellar population is being traced, and also the effects of internal dust within the galaxies are much less pronounced. In order to show the validity of our results, our primary database of aperture photometry from de Vaucouleurs & Longo (1988) and Longo et al (1983) will be compared to CCD BVI band and near-infrared imaging.

Bergmann, T. S.; Marcum, P. M.

1998-01-01

136

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

SciTech Connect

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.

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

2009-07-10

137

Late-2012 Photometry of SN 2009ip  

NASA Astrophysics Data System (ADS)

The object designated SN 2009ip was first noted in NGC 7259 in August 2009. There was evidence of photometric variability in the years preceding discovery and when it brightened again in July 2010 it was classified as a SN impostor. The latest pair of outbursts in July 2012 and September 2012 may have been a terminal SN explosion. We present V, Rc, and Ic-band photometry following the September 2012 event along with an analysis of periodic brightness fluctuations that were recorded during its decline in brightness.

Martin, John C.; Hambsch, F.; Tan, T. G.; Curtis, I. A.

2013-06-01

138

Charles Nordmann and Multicolour Stellar Photometry  

NASA Astrophysics Data System (ADS)

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.

Lequeux, James

2010-11-01

139

uvby photometry in NGC 7419 (Marco+, 2013)  

NASA Astrophysics Data System (ADS)

The open cluster NGC 7419 is known to contain five red supergiants and a very high number of Be stars. However, there are conflicting reports about its age and distance that prevent a useful comparison with other clusters. We intend to obtain more accurate parameters for NGC 7419, using techniques different from those of previous authors, so that it may be used as a calibrator for more obscured clusters. We obtained Stroemgren photometry of the open cluster NGC 7419, as well as classification spectroscopy of ~20 stars in the area. We then applied standard analysis and classification techniques. (3 data files).

Marco, A.; Negueruela, I.

2013-02-01

140

Multicolor photometry of outer Jovian satellites  

NASA Astrophysics Data System (ADS)

Multicolor photometry was obtained of satellites J6 Himalia, J7 Elara, and J10 Lysithea in the prograde cloud of outer Jovian satellites, and of J8 Pasiphae, J9 Sinope, and J11 Carme in the retrograde cloud. The data for J9 are fragmentary; otherwise, the satellites all look like C-class asteroids, except J11, which shows a remarkable brightness in the ultraviolet. The absence of D-class spectra among the outer Jovian satellites suggests that they were not derived from the same population as the outer-belt and Trojan asteroid populations.

Tholen, D. J.; Zellner, B.

1984-05-01

141

Near Infrared Photometry of Nova Del 2013  

NASA Astrophysics Data System (ADS)

Subjects: Infra-Red, Nova We report RIJHKLM photometry of Nova Del 2013 taken on August 28.13 UT using an As:Si bolometer mounted on the 0.76-m infrared telescope of the University of Minnesota's O'Brien Observatory (Marine on St. Croix, Minnesota, USA). Vega (alpha Lyrae) was used as the standard star. On this date we find: R = 5.6 +/- 0.1, I = 5.2 +/- 0.1, J = 4.5 +/- 0.1, H = 4.7 +/- 0.1, K = 4.7 +/- 0.1, L = 3.3 +/- 0.2, M = +1.8 +/- 0.3.

Cass, C. A.; Carlon, L. R.; Corgan, T. D.; Dykhoff, A. D.; Gehrz, D. R.; Shenoy, P. D.

2013-08-01

142

CDD V photometry of B2 radio galaxies (Gonzalez-Serrano+, 2000)  

NASA Astrophysics Data System (ADS)

The results of V-band CCD photometry for 72 low-luminosity radio galaxies from the B2 sample is presented. Most of these galaxies are of early type and their photometric and morphological properties are studied in the paper. We present the resulting surface brightness profiles and isophote parameters' profiles, including ellipticity, position angle, and B4, for 59 galaxies. (2 data files).

Gonzalez-Serrano, J. I.; Carballo, R.

1999-11-01

143

JHK photometry of CBJC 8 sources (Persi+, 2011)  

NASA Astrophysics Data System (ADS)

Coordinates (J2000) and JHK photometry are given for the 493 sources detected with PANIC on Baade Telescope in an area of 111"x111" centred on G85.40+0.00 as well as photometry in the four IRAC bands measured on archive frames of the same area. (2 data files).

Persi, P.; Tapia, M.; Gomez, M.

2010-11-01

144

WISE photometry of EXor sources and candidates  

NASA Astrophysics Data System (ADS)

We present a collection of WISE photometry of EXor sources and candidates (more recently identified). This represents the first complete survey of such objects in the mid-IR (3.4-22 ?m) that was carried out with the same instrumentation. Two-color diagrams constructed with WISE data evidence a clear segregation between classical and newly identified sources, being these latter characterized by colder (and less evolved) circumstellar disks. By combining 2MASS and WISE data, we obtain spectral energy distributions (SED's) that are compatible with the existence of an inner hole in the circumstellar disk. A compilation of all EXor observations given in the literature at wavelengths very similar to those of WISE is also provided. This allows us to study their mid-IR variability, which has been poorly investigated so far and without any coordination with surveys at shorter wavelengths. The presented WISE photometry and the compilation of the literature data are intended as a first step toward the construction of a significant database in this spectral regime. Preliminary indications on the mechanisms responsible for the luminosity fluctuations are provided.

Antoniucci, S.; Giannini, T.; Lorenzetti, D.

2013-10-01

145

A GUI for Aperture Photometry in IRAF  

NASA Astrophysics Data System (ADS)

A graphical user interface for an interactive IRAF application which does fractional pixel aperture photometry through circular, rectangular, or polygonal apertures is presented. The GUI provides facilities for interactively selecting and displaying the image data, selecting and marking the object and background regions to be analyzed, displaying and editing the algorithm parameters, and simultaneously displaying the results both graphically and in text format. Graphical display of the results of the analysis are in the form of a zoomed and marked image display and profile plots of the region of interest, and histogram plots of the associated background region. The GUI uses the new IRAF widget server prototype, which allows the GUI to be well isolated from the photometry code while still permitting a tightly integrated application to be developed. The prototype widget server provides custom IRAF widgets for the graphics and image display plus a selection of standard toolkit widgets such as buttons and menus, allowing IRAF applications to be developed with custom GUIs.

Davis, L. E.

146

Oxidative Damage to DNA of Ovarian Surface Epithelial Cells Affected by Ovulation: Carcinogenic Implication and Chemoprevention  

Microsoft Academic Search

The majority of cancers of the ovary are thought to originate from a surface epithelial cell perturbed by ovulation. Outgrowth of a follicle destined to ovulate brings it into apposition with the ovarian epithelium. Ovarian surface cells are consequently exposed, within a limited diffusion radius, to inflammatory agents and reactive oxidants generated during periovulatory processes. Cells that overlie the formative

WILLIAM J. MURDOCH; JAMES F. MARTINCHICKy

147

Can Surface Erosion Affect Even the Deepest Part of Lithospheric Plates?  

NASA Astrophysics Data System (ADS)

It has been demonstrated that climate-controlled surface erosion can have an strong influence on the internal evolution of the crust during plate collision and orogenesis. Here, thermal-mechanical numerical experiments are used to consider if the influence of such surface processes extends deeper, into the sub-crustal lithosphere (mantle lithosphere). The models reveal that during the early stages of continental plate collision, the modification of crustal mass flux by surface weathering can modify the stress regime within the crust and at the crust-mantle interface. The modified behaviour ofthis thick crustal layer can alter the behaviour of the underlying mantle lithosphere.With active surface erosion stable subduction-like plate consumption is maintained. In the absence of erosion, subduction is inhibited by accumulating crust causing the convergent plates to steepen dip, detach, and reverse consumption polarity. In an experiment with strong subducting plates with strain weakening, the removal of surface processes can modulate the system from stable subduction to a phase of delamination/retreat of the convergent lithospheric plate. The variation of surface (potentially also submarine) erosion is not as significant at ocean plate collision where there is relatively little bouyant crust to clog the subduction zone. The results of the experiments demonstrate that in certain tectonic regimes the influence of climate-controlled surface processes may reach much deeper into the lithosphere than has previously been appreciated.

Pysklywec, R. N.

2006-12-01

148

Osteopontin presentation affects cell adhesion-Influence of underlying surface chemistry and nanopatterning of osteopontin.  

PubMed

Osteopontin is a promising coating material for biomaterials, being important both in remodeling and formation of mineralized tissue and in immunological responses. We have investigated cell attachment to osteopontin adsorbed at different surface chemistries (-NH(2), -COOH, -CH(3), and bare gold) and to osteopontin presented as a nanopattern of 50 nm protein patches separated by a nonadhesive background. MDA-MB-435 cells adhere well to osteopontin presented at the hydrophilic chemistries (-NH2, -COOH, and gold) suggesting that osteopontin is presented in a functional form on these surfaces. On the amine surface, the cell attachment appears partly driven by electrostatic attraction between the positively charged substrate and the negatively charged cell membrane, whereas the spreading of the cells depends on the specific interaction with osteopontin presented at the surface. Significantly, fewer cells adhere to osteopontin presented at the methyl-terminated hydrophobic surface and the cells are less spread. On the nanopatterned osteopontin, only a very low number of cells adhered and those few attached cells showed an elongated morphology with few adhesion points to the surface. This indicates that the adhesive patches are not large enough to support stable focal contacts. The good cell attachment and spreading on the hydrophilic surfaces holds promise for osteopontin as a future coating for biomaterials. PMID:20665679

Malmström, Jenny; Christensen, Brian; Lovmand, Jette; Sørensen, Esben S; Duch, Mogens; Sutherland, Duncan S

2010-11-01

149

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

PubMed

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

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

2013-09-10

150

uvby photometry of BH Vir (Clement+ 1997)  

NASA Astrophysics Data System (ADS)

This paper presents new complete uvby light curves of the late-type detached eclipsing binary BH Vir (G0V + G5V, P=0.81687099d). This binary system has been observed during four campaigns at the Calar Alto Observatory (Almeria, Spain) and at the European Southern Observatory (La Silla, Chile). This observations are part of a 6 year uvby and H{beta} monitoring program of low mass eclipsing binaries which main objective is to provide accurate absolute astrophysical parameters for late-type main sequence stars. 1585 points spreaded over the binary period and covering both eclipses are given. The internal accuracy of the standard photometry measured as the mean RMS of the differences between standard value and observed value for the standard stars observed along the program is quoted in a few millimagnitudes. Detailed analysis of BH Vir, based on these light curves, will be published separately. (2 data files).

Clement, R.; Garcia, M.; Reglero, V.; Clausen, J. V.; Bravo, A.; Suso, J.; Fabregat, J.

1996-09-01

151

Techniques for Automated Single-Star Photometry  

NASA Astrophysics Data System (ADS)

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.

Henry, Gregory W.

2001-02-01

152

Gaia photometry: methods, performances and problems  

NASA Astrophysics Data System (ADS)

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.

Jordi, C.

2011-02-01

153

VBLUW photometry of some halo field giants  

NASA Astrophysics Data System (ADS)

Walraven photometry has been obtained for a sample of 43 metal-deficient halo giants and 35 stars with known values of Teff, log g and [Fe/H]. A calibration of Walraven photometric indices in terms of ? = 5040K/Teff and [Fe/H] is established. The metallicities derived for the sample of halo giants are in good agreement with those of Kraft et al. (1982). In contrast to the metallicities derived by Bond (1980), the authors find a considerably lower number of stars with [Fe/H] < -2.7 dex. The calibration yields a metallicity of -2.9 dex for CoD-38°245, which is in contrast to the extremely low value of -4.6 dex based on a spectroscopic abundance determination by Bessell and Norris (1981). The importance of this star for the calibration of photometric metallicities in the domain of extreme metal deficiency is discussed.

Nelles, B.; Richtler, T.; Seggewiss, W.

1984-10-01

154

TERMS PHOTOMETRY OF KNOWN TRANSITING EXOPLANETS  

SciTech Connect

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.

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

155

Biogenic nanoparticulate UO 2: Synthesis, characterization, and factors affecting surface reactivity  

NASA Astrophysics Data System (ADS)

The surface reactivity of biogenic, nanoparticulate UO 2 with respect to sorption of aqueous Zn(II) and particle annealing is different from that of bulk uraninite because of the presence of surface-associated organic matter on the biogenic UO 2. Synthesis of biogenic UO 2 was accomplished by reduction of aqueous uranyl ions, UO22+ by Shewanella putrefaciens CN32, and the resulting nanoparticles were washed using one of two protocols: (1) to remove surface-associated organic matter and soluble uranyl species (NAUO2), or (2) to remove only soluble uranyl species (BIUO2). A suite of bulk and surface characterization techniques was used to examine bulk and biogenic, nanoparticulate UO 2 as a function of particle size and surface-associated organic matter. The N 2-BET surface areas of the two biogenic UO 2 samples following the washing procedures are 128.63 m 2 g -1 (NAUO2) and 92.56 m 2 g -1 (BIUO2), and the average particle sizes range from 5-10 nm based on TEM imaging. Electrophoretic mobility measurements indicate that the surface charge behavior of biogenic, nanoparticulate UO 2 (both NAUO2 and BIUO2) over the pH range 3-9 is the same as that of bulk. The U L III-edge EXAFS spectra for biogenic UO 2 (both NAUO2 and BIUO2) were best fit with half the number of second-shell uranium neighbors compared to bulk uraninite, and no oxygen neighbors were detected beyond the first shell around U(IV) in the biogenic UO 2. At pH 7, sorption of Zn(II) onto both bulk uraninite and biogenic, nanoparticulate UO 2 is independent of electrolyte concentration, suggesting that Zn(II) sorption complexes are dominantly inner-sphere. The maximum surface area-normalized Zn(II) sorption loadings for the three substrates were 3.00 ± 0.20 ?mol m -2 UO 2 (bulk uraninite), 2.34 ± 0.12 ?mol m -2 UO 2 (NAUO2), and 2.57 ± 0.10 ?mol m -2 UO 2 (BIUO2). Fits of Zn K-edge EXAFS spectra for biogenic, nanoparticulate UO 2 indicate that Zn(II) sorption is dependent on the washing protocol. Zn-U pair correlations were observed at 2.8 ± 0.1 Å for NAUO2 and bulk uraninite; however, they were not observed for sample BIUO2. The derived Zn-U distance, coupled with an average Zn-O distance of 2.09 ± 0.02 Å, indicates that Zn(O,OH) 6 sorbs as bidentate, edge-sharing complexes to UO 8 polyhedra at the surface of NAUO2 nanoparticles and bulk uraninite, which is consistent with a Pauling bond-valence analysis. The absence of Zn-U pair correlations in sample BIUO2 suggests that Zn(II) binds preferentially to the organic matter coating rather than the UO 2 surface. Surface-associated organic matter on the biogenic UO 2 particles also inhibited particle annealing at 90 °C under anaerobic conditions. These results suggest that surface-associated organic matter decreases the reactivity of biogenic, nanoparticulate UO 2 surfaces relative to aqueous Zn(II) and possibly other environmental contaminants.

Singer, David M.; Farges, François; Brown, Gordon E., Jr.

2009-06-01

156

Restoration and Photometry of Full-Disk Solar Images  

NASA Astrophysics Data System (ADS)

Daily, photometric, full-disk digital solar images have been taken at the San Fernando Observatory (SFO) in several wavelengths for more than 10 years. This work describes a project to evaluate and remove the effects of scattered light from the images, while preserving the photometry. We model both the solar limb and the point-spread function analytically, and the algorithm uses a least-squares fitting technique that does not require artificial extension of the data. Image restoration is carried out using standard techniques, with the exception of a method for estimating a non-white noise component. We show using artificial solar images with ``sunspots'' and ``faculae'' that the effects of blurring are greater near the solar limb, but that the restorations recover most of the actual contrast of surface features. Images taken with two different telescopes, after restoration, show surface feature contrasts that are in better agreement than before the restoration. In addition, the measured umbral contrast of approximately -90% on restored images at 6723 Å is the expected contrast value for umbral temperatures near 3000 K. Modeling of the solar irradiance using restored images instead of the original images from a 3 month period in 1988 shows no advantage if we use variations in sunspot deficit and facular excess to model irradiance variations. However, a new parameter, the model total irradiance derived from restored broadband red images, can model the actual solar irradiance during this period with an R^2 value of 0.96.

Walton, Stephen R.; Preminger, Dora G.

1999-04-01

157

Towards understanding how surface life can affect interior geological processes: a non-equilibrium thermodynamics approach  

Microsoft Academic Search

Life has significantly altered the Earth's atmosphere, oceans and crust. To what extent has it also affected interior geological processes? To address this question, three models of geological processes are formulated: mantle convection, continental crust uplift and erosion and oceanic crust recycling. These processes are characterised as non-equilibrium thermodynamic systems. Their states of disequilibrium are maintained by the power generated

J. G. Dyke; F. Gans; A. Kleidon

2011-01-01

158

Chemical and physical modifications to poly(dimethylsiloxane) surfaces affect adhesion of Caco-2 cells.  

PubMed

Polydimethylsiloxane (PDMS) silicone elastomer is extensively used in soft lithography processes to fabricate microscale or nano scale systems for microfluidic or cell culture applications. Though PDMS is biocompatible, it is not an ideal material for cell culture due to its poor cell adhesion properties. In this study, PDMS surfaces were modified to promote intestinal cell adhesion, in the interest of testing feasibility of using microfabricated PDMS systems for high throughput drug screening. Modification techniques included changing chemical composition of PDMS (i.e., varying curing to mixing agent ratio, and oxidization of PDMS surface by oxygen plasma), surface treatment of PDMS by coating with charged molecules (i.e., poly-D-lysine, L-alpha-phosphatidylcholine, and a layer bylayer coating), and deposition of extracellular matrix (ECM) proteins (i.e., laminin, fibronectin, and collagen). The influence of these modifications on PDMS properties, including elastic modulus and surface properties (wettability, chemical composition, topography, and protein adsorption) were characterized. Modification techniques were all found to change PDMS properties and influence the attachment and proliferation of Caco-2 cells over three days of culture to varying degrees. Generally, Caco-2 cells preferred to attach on collagen-coated, fibronectin-coated, and fibronectin-coated oxygen-plasma treated PDMS. The results highlight the importance of considering multiple physical and chemical factors that may be influenced by biomaterial modification and result in altered cell attachment to microfabricated systems, including surface hydrophobicity, chemical composition, stiffness, and topography. This study provides a foundation for further miniaturization, utilizing soft lithography techniques, of Caco-2 cell-based system for high-throughput screening of drug intestinal absorption during lead optimization in drug discovery. The understanding of different surface modifications on adjusting cell adhesion on PDMS allows systemic design of Biomicroelectromechanical Systems (BioMEMS) with tunable cell adhesion properties. PMID:19827104

Wang, Lin; Sun, Bing; Ziemer, Katherine S; Barabino, Gilda A; Carrier, Rebecca L

2010-06-15

159

How subsurface patterns affect surface energy budget patterns: a sudanian case study  

NASA Astrophysics Data System (ADS)

Fractured bedrock areas are still challenging for hydrological modeling because of their complex underground property distributions. The heterogeneity in soil hydraulic properties, for example, can control the subsurface water fluxes and create surface soil moisture pattern which becomes preferential areas for runoff production or evapotranspiration. This study aimed to evaluate the impact of a bedrock topography, including outcropping, on subsurface water fluxes and the induced energy budget patterns at the surface. To deal with these ground water/surface water interactions, we run the Parflow-CLM distributed coupled land surface and groundwater model over the 12km2 Ara watershed (Northern Benin) for different bedrock configurations. The Ara catchment is submitted to a sudanian climate with 1200mm total rainfall per year. It is part of the AMMA-Catch project in which 3 meso sites have been documented along a south to north transect in West Africa. The geology of the Ara catchment is composed of metamorphic rocks. The main orientation of the geological structures (and of the gneiss foliation) is roughly north-south and the dip angle is 20° east. These structure create patterns in effective porosity distribution which is supposed to induce subsurface flow perpendicular to surface slope direction. Controlled Parflow-CLM simulation results are compared with energy budget data, including 3 net radiation measurements, eddy covariance station, scintillometric measurements to estimate evapotranspiration at different scales. The experimental device also include ground measurements like distributed surface soil moisture profile and piezometers. Parflow-CLM simulations are in good agreement with energy budget observations if observed Leaf Area Index time series are take into account. Then different hydraulic property distributions (effective porosity, hydraulic transmissivity, water retention curves) are evaluated through watershed dynamic differences.

Robert, D.; Cohard, J.; Descloitres, M.; Vandervaere, J.; Braud, I.; Vauclin, M.

2011-12-01

160

Surface tension and contact angle of herbicide solutions affected by surfactants  

Microsoft Academic Search

Contact angle and surface tension were measured for distilled and hard water solutions of adjuvants, Ortho X-77, Span-20,\\u000a Sterox-NJ. Surfactant-WK, Triton B-1956, Triton X-114, Tween-20, and Sun Oil 11E. The same parameters were measured for suspensions\\u000a of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] and ametryne [2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine] with and without each adjuvant. All adjuvants reduced surface tension and contact angle of distilled water; Surfactant-WK\\u000a was

Megh Singh; J. R. Orsenigo; D. O. Shah

1984-01-01

161

Detoxification of implant surfaces affected by peri-implant disease: an overview of surgical methods.  

PubMed

Purpose. Peri-implantitis is one of the major causes of implant failure. The detoxification of the implant surface is necessary to obtain reosseointegration. The aim of this review was to summarize in vitro and in vivo studies as well as clinical trials that have evaluated surgical approaches for detoxification of the implant body surfaces. Materials and Methods. A literature search was conducted using MEDLINE (PubMed) from 1966 to 2013. 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, radiographic bone fill, and histological reosseointegration. Results. From 574 articles found, 76 were analyzed. The findings, advantages, and disadvantages of using mechanical, chemical methods and lasers are discussed. Conclusions. Complete elimination of the biofilms is difficult to achieve. All therapies induce changes of the chemical and physical properties of the implant surface. Partial reosseointegration after detoxification has been reported in animals. Combination protocols for surgical treatment of peri-implantitis in humans have shown some positive clinical and radiographic results, but long-term evaluation to evaluate the validity and reliability of the techniques is needed. PMID:23983691

Valderrama, Pilar; Wilson, Thomas G

2013-08-04

162

Cloning and Analysis of a Candida albicans Gene That Affects Cell Surface Hydrophobicity  

PubMed Central

The opportunistic pathogenic yeast Candida albicans exhibits growth phase-dependent changes in cell surface hydrophobicity, which has been correlated with adhesion to host tissues. Cell wall proteins that might contribute to the cell surface hydrophobicity phenotype were released by limited glucanase digestion. These proteins were initially characterized by their rates of retention during hydrophobic interaction chromatography–high-performance liquid chromatography and used as immunogens for monoclonal antibody production. The present work describes the cloning and functional analysis of a C. albicans gene encoding a 38-kDa protein recognized by the monoclonal antibody 6C5-H4CA. The 6C5-H4CA antigen was resolved by two-dimensional electrophoresis, and a partial protein sequence was determined by mass spectrometry analysis of tryptic fragments. The obtained peptides were used to identify the gene sequence from the unannotated C. albicans DNA database. The antibody epitope was provisionally mapped by peptide display panning, and a peptide sequence matching the epitope was identified in the gene sequence. The gene sequence encodes a novel open reading frame (ORF) of unknown function that is highly similar to several other C. albicans ORFs and to a single Saccharomyces cerevisiae ORF. Knockout of the gene resulted in a decrease in measurable cell surface hydrophobicity and in adhesion of C. albicans to fibronectin. The results suggest that the 38-kDa protein is a hydrophobic surface protein that meditates binding to host target proteins.

Singleton, David R.; Masuoka, James; Hazen, Kevin C.

2001-01-01

163

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...

164

Shear strength of surface soil as affected by soil bulk density and soil water content  

Microsoft Academic Search

This paper proposes a new method to measure the soil strength parameters at soil surface in order to explain the processes of soil erosion and sealing formation. To simulate the interlocks between aggregates or particles within top 2mm of the soil, a piece of sandpaper (30 particles cm?2) was stuck on the bottom face of a plastic box of diameter

B Zhang; Q. G Zhao; R Horn; T Baumgartl

2001-01-01

165

Detoxification of Implant Surfaces Affected by Peri-Implant Disease: An Overview of Surgical Methods  

PubMed Central

Purpose. Peri-implantitis is one of the major causes of implant failure. The detoxification of the implant surface is necessary to obtain reosseointegration. The aim of this review was to summarize in vitro and in vivo studies as well as clinical trials that have evaluated surgical approaches for detoxification of the implant body surfaces. Materials and Methods. A literature search was conducted using MEDLINE (PubMed) from 1966 to 2013. 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, radiographic bone fill, and histological reosseointegration. Results. From 574 articles found, 76 were analyzed. The findings, advantages, and disadvantages of using mechanical, chemical methods and lasers are discussed. Conclusions. Complete elimination of the biofilms is difficult to achieve. All therapies induce changes of the chemical and physical properties of the implant surface. Partial reosseointegration after detoxification has been reported in animals. Combination protocols for surgical treatment of peri-implantitis in humans have shown some positive clinical and radiographic results, but long-term evaluation to evaluate the validity and reliability of the techniques is needed.

Wilson Jr, Thomas G.

2013-01-01

166

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-...

167

Spatial variation of charge and sulfur oxidation state in a surface gradient affects plasma proteins adsorption  

PubMed Central

A gradient of negative surface charge based on 1-D spatial variation from surface sulfhydryl to mixed sulfhydryl-sulfonate moities was prepared by controlled UV oxidation of 3-mercaptopropylsilane monolayer on fused silica. Adsorption of three human plasma proteins, albumin (HSA), immunoglobulin G (IgG), and fibrinogen (Fgn) onto such surface gradient was studied using spatially-resolved total internal reflection fluorescence (TIRF) and autoradiography. Adsorption was measured from dilute solutions equivalent to 1/100 (TIRF, autoradiography), and 1/500 and 1/1000 (autoradiography) of protein’s physiological concentrations in plasma. All three proteins adsorbed more to the non-oxidized sulfhydryl region than to the oxidized, mixed sulfhydryl-sulfonate region of the gradient. In the case of HSA the adsorption contrast along the gradient was largest when the adsorption took place from more dilute protein solutions. Increasing the concentration to 1/100 of protein plasma concentration eliminated the effect of the gradient on HSA adsorption and to the lesser extent on IgG adsorption. In the case of Fgn the greatest adsorption contrast was observed at the highest concentration used. Based on adsorption kinetics, the estimated binding affinity of HSA for the sulfhydryl region what twice the affinity for the mixed sulfhydryl-sulfonate region of the gradient. For IgG and Fgn the initial adsorption was transport-limited and the initial adsorption rates approached the computed flux of the protein to the surface.

Ding, Yong-Xue; Streitmatter, Seth; Wright, Bryon E.; Hlady, Vladimir

2010-01-01

168

Disk-resolved photometry of Asteroid (2867) Steins  

NASA Astrophysics Data System (ADS)

We present a new method to perform disk-resolved photometry in order to investigate the intrinsic photometric properties of the surface of small Solar System bodies. We adopt the standard approach where a shape model is combined with a photometric formalism - in practise the Hapke formalism - to remove the effects of topography and recover the photometric (Hapke) parameters of either the global surface or, in its most elaborated form, the spatial variations of these parameters across the surface. Our method operates in the space of the facets representing the three-dimensional shape of the body, whereas all past analysis have always been performed in the space of the image pixels although they are not intrinsic to the surface of the body. This has the advantage of automatically tracking the same local surface element on a series of images. We first apply our method to images of the nucleus of Comet 9P/Tempel 1 obtained by the High-Resolution Imager (HRI) instrument on board the Deep Impact spacecraft and our derived Hapke parameters are in good agreement with those published by Li et al. (Li, J.-Y. et al. [2007]. Icarus 187, 41-55) within their respective uncertainties. We confirm the presence of an extended region of higher roughness in the southern hemisphere of the nucleus and the higher albedo of the ice-rich regions identified by Sunshine et al. (Sunshine, J.M. et al. [2006]. Science 311, 1453-1455) near the equator. The photometric properties of Asteroid (2867) Steins are then studied from multi-spectral images obtained with the OSIRIS Wide Angle Camera (WAC) on board the Rosetta spacecraft during its flyby on 5 September 2008. Our analysis indicates that the surface is highly porous (˜84%) and that it exhibits both a shadow-hiding opposition effect (SHOE) and probably, a coherent-backscatter opposition effect (CBOE). The single scattering albedo is the highest (SSA = 0.57) ever observed among small bodies visited by spacecrafts. Our modelled roughness parameter is indicative of a high microscale roughness. The surface of Steins may in fact exhibit a fractal surface with high roughness present on a large range of scales, from micrometers to centimeters. The geometric and Bond albedos are calculated with the Hapke parameters yielding Ap = 0.39 ± 0.02 and AB = 0.24 ± 0.01. This high albedo is consistent with an iron-poor surface composition similar to aubrite meteorites which are suspected to originate from the E-type asteroids. We find no photometric variations on the surface at the (limited) spatial resolution of the WAC images.

Spjuth, S.; Jorda, L.; Lamy, P. L.; Keller, H. U.; Li, J.-Y.

2012-11-01

169

Surface kinetics and subplantation phenomena affecting the texture, morphology, stress, and growth evolution of titanium nitride films  

NASA Astrophysics Data System (ADS)

We present a thorough study of the microstructure, texture, intrinsic stress, surface, and interface morphology of transition metal nitride (mainly TiN but also CrN) films grown on Si by reactive sputter deposition, with emphasis to the mechanisms of adatom migration on the surface and subplantation of energetic species. In order to study the effects of adatom mobility and the subplantation probability we vary the ion energy and growth temperature. For the experimental part of this work we used nondestructive, statistically reliable x-ray techniques (diffraction, reflectivity, scattering). The x-ray results are compared and correlated with supporting data of in situ spectroscopic ellipsometry as well as Monte Carlo simulations of the irradiation effects and surface diffusion of adatoms. We found that the texture and the surface and interface morphology are sensitive to the mechanism of dissipation of the impinging ions. If the energy is enough to overcome the subplantation threshold (~50 eV), then the films are highly compressed and exhibit ultrasmooth surfaces and rough interfaces. In this case, the texture of the films is not affected much by the ion energy, since the energy is dissipated in the bulk and contributes less to the surface mobility of adatoms. On the other hand, when the ion energy is below the subplantation threshold the texture of the films strongly depends on the ion energy and flux, the interfaces are atomically sharp and the surface morphology depends on the mobility and surface diffusion length of adatoms. However, in both cases these effects are dominant at the homogeneous growth. At the initial stages of nucleation and island growth the differences in the growth due to irradiation conditions are not pronounced and the thermodynamics of wetting of TiN on Si are prevailing factors.

Patsalas, P.; Gravalidis, C.; Logothetidis, S.

2004-12-01

170

Surface hydrophobicity, nutritional contents affect Staphylococcus aureus biofilms and temperature influences its survival in preformed biofilms.  

PubMed

The present study investigates the effect of surface hydrophobicity and media on in vitro biofilm formation potential of S. aureus isolates from two dairies. There was lack of correlation between biofilm formation potential of S. aureus and sampling points but not with the source of isolation. Biofilm formation was more pronounced on hydrophobic polypropylene (PP) than hydrophilic stainless steel (SSC). A better correlation was established between the biofilms on SSC and PP when analyzed by crystal violet staining than conventional plating method. On comparative evaluation of nutrient rich and diluted growth media, enhanced biofilm formation was observed in latter (1/20 tryptic soya broth). Highest survival in the preformed biofilms was observed at incubation temperature of 25 °C in sterilized skim milk rather than TSB. The present study signify preferable adherence of S. aureus on hydrophobic surfaces and potential survival within preformed biofilm at temperatures prevalent in dairy industries. PMID:20586075

Pagedar, Ankita; Singh, Jitender; Batish, Virender K

2010-12-01

171

Internal processes affecting surfaces of low-density satellites: Ganymede and Callisto  

Microsoft Academic Search

Internal processes operating within low-density satellites, although they are poorly understood at present, are extremely significant in determining the scale and type of surface processes and features and the geologic evolution of such satellites. The two Galilean satellites Ganymede and Callisto are examples of such low-density (rho<2) bodies, and they are likely to have undergone a thermal evolution which resulted

E. M. Parmentier; James W. Head

1979-01-01

172

Surface modification of poly( l -lactic acid) affects initial cell attachment, cell morphology, and cell growth  

Microsoft Academic Search

The object of this study was to develop a highly porous scaffold to be used in regeneration of blood vessels, nerves, and other hollow tissues with small openings. Using the phase-inversion method and a mixture of water and methanol as a coagulating agent, we prepared highly porous flat membranes from poly(l-lactic acid) (PLLA) with numerous pores both on the surface

Manae Yamaguchi; Toshio Shinbo; Toshiyuki Kanamori; Pi-chao Wang; Motohiro Niwa; Hiroyoshi Kawakami; Shoji Nagaoka; Kohichiro Hirakawa; Masahiro Kamiya

2004-01-01

173

Factors Affecting Cake Firmness and Cake Moisture Content as Evaluated by Response Surface Methodology  

Microsoft Academic Search

Cereal Chem. 75(4):547-550 Values of initial fat temperature, mixing intensity, mixing time, and mass ratio of fat and sucrose (F\\/S ratio) were varied in the preparation of fat-sugar cream. The dependence of cake firmness and cake moisture content on these values, the size of sucrose particles, and storage time were studied using re- sponse surface methodology. The logarithm of storage

S. Lahtinen; M. Levola; K. Jouppila; H. Salovaara

1998-01-01

174

Adhesion and Spatial Distribution of Water in the Presence of Moisture: Surface Chemistry Affects.  

NASA Astrophysics Data System (ADS)

Many polymer adhesive bonds experience a complete loss of adhesion above a critical threshold relative humidity value. The adhesion loss from water exposure does not generally correlate with moisture solubility of the polymer; instead the surface layer of the polymer appears to be the controlling factor in the adhesion. Here, the adhesion and spatial distribution of water of a series of PMMA-Al adhesive samples in the presence of moisture is measured with neutron reflectivity, while the adhesive strength of the joint is measured using the shaft-loaded blister test. The role of changing surface chemistry was examined to determine their effect on this interfacial moisture content. The loss of adhesive strength upon exposure to moisture correlates directly with the interfacial water content. Surface modification methods that decrease the interfacial water content are used to tune the adhesive strength in moist environments. Minimization of the interfacial water concentration does not however result in the best adhesion in moist environments as interplay between the dry adhesion and water content exists.

White, Chrisopher; Vogt, Bryan; O'Brien, Emmett; Wu, Wen-Li

2006-03-01

175

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

PubMed

The fate of (137)Cs 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 (137)Cs in forest surface (0-3 cm) soils. The K(2)SO(4) extraction process liberated 2.1%-12.8% of the total (137)Cs from the soils. Two soils with a higher content of clay- and silt-sized particles, organic carbon content, and cation exchange capacity showed higher (137)Cs extractability. Microbial biomass was observed in all of the soils. However, the (137)Cs extractability did not increase after destruction of the microbial biomass by chloroform fumigation, providing no evidence for microbial retention of the Fukushima-fallout (137)Cs. The results indicate that uptake of (137)Cs by soil microorganisms is less important for retention of potentially mobile (137)Cs in the forest surface soils compared to ion-exchange adsorption on non-specific sites provided by abiotic components. PMID:23256039

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

2012-12-19

176

Multicolour photometry of edge-on and box/peanut galaxies  

NASA Astrophysics Data System (ADS)

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.

Petrov, Georgi; Dettmar, Ralf-Jurgen

177

VI photometry of the Leo II galaxy (Bellazzini+, 2005)  

NASA Astrophysics Data System (ADS)

V and I photometry and astrometry for 2715 stars in a 9.4'x9.4' field centered on the Leo II dwarf spheroidal galaxy. Photometric system: Johnson-Kron-Cousins (Landolt's photometric standards). (1 data file).

Bellazzini, M.; Gennari, N.; Ferraro, F. R.

2005-06-01

178

SYNMAG Photometry: Catalog-level Matched Colors of Extended Sources  

NASA Astrophysics Data System (ADS)

SYNMAG is a tool for producing synthetic aperture magnitudes to enable fast matched photometry at the catalog level without reprocessing imaging data. Aperture magnitudes are the most widely tabulated flux measurements in survey catalogs; 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. An alternative solution called "synthetic aperture photometry" 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.

Bundy, Kevin; Hogg, David W.; Higgs, Tim D.; Nichol, Robert C.; Yasuda, Naoki; Masters, Karen L.; Lang, Dustin; Wake, David A.

2013-02-01

179

Feasibility Study of Coal Dust Measurement by Light Reflectance Photometry.  

National Technical Information Service (NTIS)

This report describes the design, fabrication, and testing of a proto-type instrument that demonstrates the feasibility of determining respirable coal dust concentrations by light reflectance photometry. Coal dust is collected on a filter and the amount c...

I. Pritts G. A. Bertone

1981-01-01

180

Improved Asteroid Astrometry and Photometry with Trail Fitting  

NASA Astrophysics Data System (ADS)

We present the trail fitting algorithm that introduces the trail equation. Our demonstration of trail and PSF fitting on synthetic and Pan-STARRS PS1 detected asteroid detections leads to improved astrometry and photometry of trailed detections.

Vereš, P.; Jedicke, R.; Denneau, L.; Wainscoat, R.; Holman, M. J.

2012-05-01

181

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

PubMed

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

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

2003-08-01

182

HU Protein Affects Transcription of Surface Polysaccharide Synthesis Genes in Porphyromonas gingivalis ? †  

PubMed Central

K-antigen capsule synthesis is an important virulence determinant of the oral anaerobe Porphyromonas gingivalis. We previously reported that the locus required for synthesis of this surface polysaccharide in strain W83 (TIGR identification PG0106 to PG0120) is transcribed as a large (?16.7-kb) polycistronic message. Through sequence analysis, we have now identified a 77-bp inverted repeat located upstream (206 bp) of the start codon of PG0106 that is capable of forming a large hairpin structure. Further sequence analysis just upstream and downstream of the capsule synthesis genes revealed the presence of two genes oriented in the same direction as the operon that are predicted to encode DNA binding proteins: PG0104, which is highly similar (57%) to DNA topoisomerase III, and PG0121, which has high similarity (72%) to DNA binding protein HU (?-subunit). In this report, we show that these two genes, as well as the 77-bp inverted repeat region, are cotranscribed with the capsule synthesis genes, resulting in a large transcript that is ?19.4 kb (based on annotation). We also show that a PG0121 recombinant protein is a nonspecific DNA binding protein with strong affinity to the hairpin structure, in vitro, and that transcript levels of the capsule synthesis genes are downregulated in a PG0121 deletion mutant. Furthermore, we show that this decrease in transcript levels corresponds to a decrease in the amount of polysaccharide produced. Interestingly, expression analysis of another polysaccharide synthesis locus (PG1136 to PG1143) encoding genes involved in synthesis of a surface-associated phosphorylated branched mannan (APS) indicated that this locus is also downregulated in the PG0121 mutant. Altogether our data indicate that HU protein modulates expression of surface polysaccharides in P. gingivalis strain W83.

Alberti-Segui, Christine; Arndt, Annette; Cugini, Carla; Priyadarshini, Richa; Davey, Mary E.

2010-01-01

183

Factors affecting survival of Shigatoxin-producing Escherichia coli on abiotic surfaces.  

PubMed

Shigatoxin-producing Escherichia coli (STEC) causes severe infections, and has been the cause of a number of foodborne outbreaks. Knowledge on the survival of STEC is crucial in order to limit the risk of cross contamination and transfer of STEC to food during processing. In this study survival of STEC and non-STEC on surfaces under various humidities, temperatures and in the presence of different types of soil was investigated. A model system with controlled relative humidity and temperature was established by using saturated salt solutions. All the 12 STEC strains had a reduction in viable count during incubation at 70% RH at 12 degrees C. The reduction was 2-3.5 log and 4.5-5.5 log after 1 and 7 days of incubation, respectively. Surviving cells were observed after 19 days of incubation. The STEC strains were more resistant to desiccation than non-STEC strains. STEC survived better at 12 degrees C, compared to 20 degrees C. The survival of STEC was much lower than the survival of a Staphylococcus simulans strain tested, which showed less than 1 log reduction until day 7 at 70% RH at 12 degrees C, while several STEC strains had comparable survival to a Salmonella Agona strain. The survival of two STEC strains tested was highest at 98% RH. The lowest survival was observed at 85% RH, with better survival at drier conditions. Presence of proteins and glucose protected the cells at dry conditions. Two commercial disinfectants tested at in-use concentration had limited effect (0.8-2.5 log reduction) against STEC on stainless steel, especially for cells incubated at high relative humidity (98% RH). STEC surviving on surfaces in the food industry may impose a risk for cross contamination. Cleaning and use of suitable disinfectants will reduce the survival of STEC, but surfaces should be allowed to dry completely since humid conditions will promote the survival and growth of STEC. PMID:20100628

Møretrø, T; Heir, E; Mo, K R; Habimana, O; Abdelgani, A; Langsrud, S

2010-01-11

184

Binary Star Synthetic Photometry and Distance Determination Using BINSYN  

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

185

Large-Scale Errors in CCD Photometry of M67  

Microsoft Academic Search

The accuracy of new CCD photometry in the Vilnius system of the M67 cluster is analyzed. The observational material is obtained during six observing runs in 1994--2001 with the 1 meter telescope of the USNO Flagstaff Station. The main task was to establish CCD standards of high accuracy and to eliminate large-scale errors from our CCD photometry. We compare our

V. Laugalys; R. P. Boyle; A. Kazlauskas; F. J. Vrba; A. G. Davis Philip; V. Straizys

2003-01-01

186

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

PubMed

Neuraminidases (sialidases) catalyse 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 spirochaete 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 spirochaete 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-C3(tm1) (Crr) /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 spirochaete to acquire nutrients and evade complement killing. PMID:23808705

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

2013-08-01

187

FIXING THE U-BAND PHOTOMETRY OF TYPE Ia SUPERNOVAE  

SciTech Connect

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.

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

188

Spitzer/IRAC Photometry Of The Four Largest Uranian Satellites  

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

189

A New Look at Photometry of the Moon  

NASA Astrophysics Data System (ADS)

We test 2 very different models for light scattering by the lunar regolith: 1) TRLA - a Topographically Rough surface layer comprised of Low Albedo particles, and 2) RTE - a flat surface layer with the published size distribution and optical constants of Apollo soil particles, Mie calculation of the mean particle scattering matrix and rigorous solution of the Radiative Transfer Equation for all orders of scattering (Mishchenko et al 1999, JQRST 63, 409). For a typical lunar highland location (-17.21, 20.01), ROLO photometry (Kieffer & Stone 2005, Astron. J. 129, 2887) shows a distinct difference between the radiances measured before and after full moon (BFM, AFM) at the same 47.5 ± 2.5 degree phase angle, corresponding to incidence angles of 30 and 70 degrees, respectively. The TRLA model requires rms slopes of 34.1 ± 2.6 degrees to reproduce this BFM/AFM radiance difference, similar to previously published results. Analysis of Apollo ALSCC stereo images of in situ lunar regolith (Helfenstein and Shepard 1999, Icarus 141, 107) shows that such large rms slopes pertain to a sub-mm horizontal distance scale. The RTE model also reproduces the same BFM/AFM radiance difference, but as a direct consequence of multiple scattering between particles within the flat (zero topographic roughness) regolith layer. Approximately 80% of the radiance in the RTE model is contributed by photons scattered more than once. We conclude that topographic roughness of the regolith surface and multiple scattering between regolith particles can have a nearly identical effect on this BFM/AFM difference in the lunar radiance. Roughness and multiple scattering are strongly correlated parameters in the sense that any approximations regarding one of them will influence the value deduced for the other. A complete treatment of this work is published in Goguen et al 2010, Icarus 208, 548.

Goguen, Jay D.; Stone, T. C.; Kieffer, H. H.; Buratti, B. J.

2010-10-01

190

[Mechanisms of bacterial inactivation as affected by cation surface-active substances].  

PubMed

The death kinetics and ultratructure of gram-positive and gram-negative bacteria exposed to alkyldimethylammonium chloride were studied. It was shown that at low concentrations (0.0001 per cent) the agent had a pronounced bactericidal effect, which was higher with respect to the gram-positive bacteria. Impairment of the intactness of the cytoplasmic membrane, a vitally important organoid of the bacterial cell, was the main factor in the mechanism of action of the cationic surface-active substance. Membrane structures of various configuration and localization not associated with the cell division were detected in the cytoplasm of the dead bacteria. These structures are probably the result of self-assembly of the membrane lipid components broken under the action of the detergent. PMID:4015059

Pavlova, I B; Samoilenko, I I

1985-03-01

191

Changes in soil DOC affect reconstructed history and projected future trends in surface water acidification  

NASA Astrophysics Data System (ADS)

Over the last two decades there has been growing evidence of widespread increasing concentrations of dissolved organic carbon (DOC) in surface waters in several regions in Europe and North America. Two main drivers have been proposed to explain this observation: climate change entailing changed humidity and temperature which alter rates of microbial processes and reductions in acid deposition which lead to decreased concentrations of strong acid anions and alter rates of decomposition and solubility of organic matter in soil. The question of historical DOC concentrations is therefore important for quantifying present-day acidification and possible future recovery of the surface waters. Due to the paucity of historical data, estimates of pre-acidification chemical and biological status usually come from modeling applications. Lack of process-understanding and of consensus upon what has been driving the observed DOC trends makes modeling uncertain and model outcomes are subject to controversy. Here we apply the MAGIC model to the long-term observed soil and streamwater chemistry data from an anthropogenically acidified small Lysina catchment, Czech Republic, to illustrate the importance of choice of source of DOC during recovery from acidification. The annual mean streamwater DOC concentration increased from 15.6-16.9 mg L-1 (1993-1994) to 21.8-24.5 mg L-1 in 2010-2011, an average annual increase of 0.6 mg L-1 year-1 (p<0.001). Even stronger DOC trends were observed for soilwater draining the organic soil horizons. Mean annual DOC increased from 41-42 mg L-1 in 1993-1994 to 67-74 mg L-1 in 2010-2011 below the organic horizon (at 5 cm depth below the surface), an annual increase of 2.7 mg L-1 year-1 (p<0.001). At 15 cm depth below the surface, in the uppermost mineral horizon (E), the DOC concentrations increased from 31-34 mg L-1 to 68-73 mg L-1, an annual increase of 1.9 mg L-1 year-1 (p<0.005) Pre-industrial (1850´s) and future (2060) streamwater chemistry was estimated using the MAGIC model for three different dissolved organic carbon (DOC) levels and sources. The highest pH = 5.7 for 1850´s as well as for 2060 (pH = 4.4) was simulated given the assumption that streamwater DOC concentration was constant at the 1993 level. A scenario accounting for an increase of DOC as an inverse function of ionic strength (it has declined as a result of decreasing acidic deposition) of soilwater and streamwater resulted in much lower pre-industrial pH=4.9 and future recovery to pH=4.1 if only stream riparian zone was taken as a DOC source. If upland soilwater (where significant DOC increase was observed at -5 cm and -15 cm) was also included, DOC was partly neutralized by base cations within the soil and pre-industrial pH=5.3 and future pH = 4.2 were estimated. The observed DOC riverine flux was 2 - 4 times higher than the potential carbon production of the riparian zone. Thus modelling pre-industrial pH based on the assumption that stream DOC changes are solely attributable to changes in the riparian zone appears likely to result in a substantial under-estimate of pre-industrial and future steamwater pH.

Hruška, Jakub; Krám, Pavel; Moldan, Filip; Oulehle, Filip; Evans, Christopher D.; Wright, Richard F.; Cosby, Bernard J.

2013-04-01

192

Analysis of some systematic errors affecting altimeter-derived sea surface gradient with application to geoid determination over Taiwan  

Microsoft Academic Search

.   This paper analyzes several systematic errors affecting sea surface gradients derived from Seasat, Geosat\\/ERM, Geosat\\/GM,\\u000a ERS-1\\/35d, ERS-1\\/GM and TOPEX\\/POSEIDON altimetry. Considering the data noises, the conclusion is: (1) only Seasat needs to\\u000a correct for the non-geocentricity induced error, (2) only Seasat and Geosat\\/GM need to correct for the one cycle per revolution\\u000a error, (3) only Seasat, ERS-1\\/GM and Geosat\\/GM

C. Hwang

1997-01-01

193

BATC photometry on A119 (Tian+, 2012)  

NASA Astrophysics Data System (ADS)

This paper presents multicolor optical photometry of the nearby galaxy cluster Abell 119 (z=0.0442) with the Beijing-Arizona-Taiwan-Connecticut system of 15 intermediate bands. Within the BATC field of view of 58'x58', there are 368 galaxies with known spectroscopic redshifts, including 238 member galaxies (called sample I). Based on the spectral energy distributions of 1376 galaxies brighter than iBATC=19.5, the photometric redshift technique and the color-magnitude relation of early-type galaxies are applied to select faint member galaxies. As a result, 117 faint galaxies were selected as new member galaxies. Combined with sample I, an enlarged sample (called sample II) of 355 member galaxies is obtained. Spatial distribution and localized velocity structure for two samples demonstrate that A119 is a dynamically complex cluster with at least three prominent substructures in the central region within 1Mpc. A large velocity dispersion for the central clump indicates a merging along the line of sight. No significant evidence for morphology or luminosity segregations is found in either sample. With the PEGASE evolutionary synthesis model, the environmental effect on the properties of star formation is confirmed. Faint galaxies in the low-density region tend to have longer time scales of star formation, smaller mean stellar ages, and lower metallicities in their interstellar medium, which is in agreement with the context of the hierarchical cosmological scenario. (3 data files).

Tian, J.-T.; Yuan, Q.-R.; Zhou, X.; Jiang, Z.-J.; Ma, J.; Wu, J.-H.; Wu, Z.-Y.; Fan, Z.; Zhang, T.-M.; Zou, H.

2012-11-01

194

BV photometry of quadrupole system ET Bootis  

NASA Astrophysics Data System (ADS)

In this study, we present the first Johnson BV photometry of the eclipsing binary star ET Bootis, which is member of a physically connected visual pair. Analysis of times of light minima enables us to calculate accurate ephemeris of the system via O-C analysis and observed an increase in period which we believe is a result of the light-time effect in the outer visual orbit. Secondly, we determined the total brightness and color of the system in light maxima and minima. Photometric solution of the system indicates that the contribution of the visual pair to the total light is about 40% in Johnson V band. Furthermore, photometric analysis shows that the primary star in the eclipsing binary has F8 spectral type while it confirms the G5 spectral type for the visual pair. Masses of the components in eclipsing binary are M1 = 1.109 ± 0.014 M? and M2 = 1.153 ± 0.011 M?. Absolute radii of the components are R1 = 1.444 ± 0.007 R? and R2 = 1.153 ± 0.007 R?. Physical properties of the components leads 176 ± 7 pc distance for the system and suggests an age of 6.5 billion years.

Özdarcan, O.; Evren, S.

2012-10-01

195

Multicolor Photometry of Trans-neptunian Objects  

NASA Astrophysics Data System (ADS)

We are continuing our photometric survey of the trans-neptunian and Centaur populations started in 1997. We report multicolor photometry for 17 objects. With these results combined with previous data (M. A. Barucci, A. Doressoundiram, M. Fulchignoni, D. Tholen, and M. Lazzarin 1999. Icarus142, 476-481; M. A. Barucci, J. Romon, A. Doressoundiram, and D. Tholen 2000. Astron. J.120, 496-500), we have at our disposal a homogeneous and high-quality set of color indices for 29 objects, numerous enough to make significant studies. The color-color diagrams confirm the wide and continuous spread of colors in the trans-neptunian object population. This diversity may be explained by the combined action of space weathering and collisional resurfacing. We do not find any correlation of colors with size or heliocentric distance, but we note an excess of red objects for perihelion distance greater than 40 AU. Furthermore, our results suggest also that highly inclined (e.g., i>17°) and eccentric objects are preferentially neutral. These objects may have suffered more collisional resurfacing than others.

Doressoundiram, A.; Barucci, M. A.; Romon, J.; Veillet, C.

2001-12-01

196

Infrared Photometry of beta Pictoris Type Systems  

NASA Astrophysics Data System (ADS)

We obtained small-aperture (4"-5" diameter) infrared (2-20 ?m) photometry of 10 early-type main-sequence stars with infrared excesses from circumstellar dust. These systems possibly exemplify the beta Pictoris phenomenon. We observed them with either the NASA Marshall Space Flight Center bolometer array camera (``Big Mac'') or the Infrared Telescope Facility 2-30 ?m single-channel bolometer system. Measurements were obtained in the KLMNQ filters and the narrowband (Deltalambda ~ 1 ?m) 10 ?m ``silicate'' filters. We fitted Kurucz photospheric models to the photometric data to determine excess-emission spectra. We report the nondetection of small-aperture circumstellar dust emission from HR 10 and 21 LMi. We confirmed previous nondetections of near-infrared or 10 ?m excess emission from 68 Oph, alpha PsA, and HR 4796A. We did not detect prominent silicate emission from any of the sources. The spectra of gamma Oph, sigma Her, HR 2174A, beta UMa, and zeta Lep show weak 10 ?m excesses. We fitted simple models to these data, together with IRAS excess fluxes, to determine plausible distributions of temperature and density of circumstellar dust grains. Significant quantities of these grains around HR 2174A, zeta Lep, and beta UMa are at temperatures similar to terrestrial material in the solar system.

Fajardo-Acosta, S. B.; Telesco, C. M.; Knacke, R. F.

1998-05-01

197

BVI CCD photometry of 47 Tucanae  

SciTech Connect

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.

Alcaino, G.; Liller, W.

1987-08-01

198

An Evaluation of the Scale at which Ground-Surface Heat Flux Patchiness Affects the Convective Boundary Layer Using Large-Eddy Simulations  

Microsoft Academic Search

The effects on the convective boundary layer (CBL) of surface heterogeneities produced by surface sensible heat flux waves with different means, amplitudes, and wavelengths were investigated here. The major objective of this study was to evaluate at which scale surface heterogeneity starts to significantly affect the heat fluxes in the CBL. The large-eddy simulation option of the Regional Atmospheric Modeling

Roni Avissar; Tatyana Schmidt

1998-01-01

199

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

SciTech Connect

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.

Hale, L C; Taylor, J S

2008-04-03

200

How does surface salinity and rain affect the North Atlantic ocean circulation?  

NASA Astrophysics Data System (ADS)

Salinity variations in recent decades have been linked to the Atlantic Meridional Overturning Circulation (MOC) strength, and the tropics/subtropics are considered important regions in relation to the reversal of northern N. Atlantic freshening and MOC recovery. This study focuses on the controlling mechanisms, particularly the influence of freshwater fluxes (Evaporation minus Precipitation, E-P), on sea surface (SSS) and upper ocean salinity (UOS) variability in the Atlantic region 30°N-S, which includes two dynamically different regimes, the P-dominated tropics and the E-dominated subtropics. Analysing various datasets for each variable (NCEP, WOA09, etc) on different time-scales, in addition to new SSS maps from the European Space Agency Soil Moisture and Ocean Salinity (SMOS) satellite, help us to consider the role of E-P on the formation, magnitude and maintenance of the subtropical Atlantic SSS maximum, the small seasonal cycle in SSS compared to that of E-P, and propagation pathways at these latitudes. This examination will contribute to a regional validation of SSS from the SMOS and Aquarius satellites in E- and P-dominated regions, and an improved definition of the variability of SSS in this region.

Tzortzi, E.; Gommenginger, C. P.; Josey, S.; Srokosz, M. A.

2012-04-01

201

Water chemistry of surface waters affected by the Fourmile Canyon wildfire, Colorado, 2010-2011  

USGS Publications Warehouse

In September 2010, the Fourmile Canyon fire burned about 23 percent of the Fourmile Creek watershed in Boulder County, Colo. Water-quality sampling of Fourmile Creek began within a month after the wildfire to assess its effects on surface-water chemistry. Water samples were collected from five sites along Fourmile Creek (above, within, and below the burned area) monthly during base flow, twice weekly during snowmelt runoff, and at higher frequencies during storm events. Stream discharge was also monitored. Water-quality samples were collected less frequently from an additional 6 sites on Fourmile Creek, from 11 tributaries or other inputs, and from 3 sites along Boulder Creek. The pH, electrical conductivity, temperature, specific ultraviolet absorbance, total suspended solids, and concentrations (dissolved and total) of major cations (calcium, magnesium, sodium, and potassium), anions (chloride, sulfate, alkalinity, fluoride, and bromide), nutrients (nitrate, ammonium, and phosphorus), trace metals (aluminum, arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, iron, mercury, lithium, manganese, molybdenum, nickel, lead, rubidium, antimony, selenium, strontium, vanadium, and zinc), and dissolved organic carbon are here reported for 436 samples collected during 2010 and 2011.

McCleskey, R. Blaine; Writer, Jeffrey H.; Murphy, Sheila F.

2012-01-01

202

How do silanes affect the lubricating properties of cationic double chain surfactant on silica surfaces?  

PubMed

The effect of an aminosilane on the lubricant properties of a C(18) double-chained cationic surfactant has been investigated in the context of glass fiber forming process. The surfactant adsorption was studied on silica by Fourier transform infrared (FT-IR) spectroscopy in the attenuated total reflexion (ATR) mode as a function of the aminosilane concentration in an organic water based formulation (sizing) used to coat the glass fibers during the process. A reciprocating ball-on-plate tribometer was used to compare friction properties of silica in contact with the aminosilane-surfactant mixture and in presence of each component of the sizing. Surface forces were measured between silica and an atomic force microscope (AFM) silicon nitride tip in the sizing and in the pure cationic surfactant solution. The aminosilane on its own has no lubricant property and reduces or even suppresses the cationic surfactant adsorption on silica. However, the silica-silica contact is lubricated even if the infrared spectroscopy does not detect any surfactant adsorption. The repeated contacts and shear due to the friction experiment itself induce accumulation, organization and compactness of surfactant bilayers. PMID:19059599

Beauvais, Muriel; Serreau, Laurence; Heitz, Caroline; Barthel, Etienne

2008-11-24

203

Surface interactions affect the toxicity of engineered metal oxide nanoparticles toward Paramecium.  

PubMed

To better understand the potential impacts of engineered metal oxide nanoparticles (NPs) in the ecosystem, we investigated the acute toxicity of seven different types of engineered metal oxide NPs against Paramecium multimicronucleatum, a ciliated protozoan, using the 48 h LC(50) (lethal concentration, 50%) test. Our results showed that the 48 h LC(50) values of these NPs to Paramecium ranged from 0.81 (Fe(2)O(3) NPs) to 9269 mg/L (Al(2)O(3) NPs); their toxicity to Paramecium increased as follows: Al(2)O(3) < TiO(2) < CeO(2) < ZnO < SiO(2) < CuO < Fe(2)O(3) NPs. On the basis of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, interfacial interactions between NPs and cell membrane were evaluated, and the magnitude of interaction energy barrier correlated well with the 48 h LC(50) data of NPs to Paramecium; this implies that metal oxide NPs with strong association with the cell surface might induce more severe cytotoxicity in unicellular organisms. PMID:22693953

Li, Kungang; Chen, Ying; Zhang, Wen; Pu, Zhichao; Jiang, Lin; Chen, Yongsheng

2012-07-06

204

Identification of pel, a Streptococcus pyogenes Locus That Affects both Surface and Secreted Proteins  

PubMed Central

A Tn917 insertion mutant of an M49 serotype, opacity factor-positive Streptococcus pyogenes, was isolated. It had the following phenotypes: decreased ?-hemolysis mediated by streptolysin S, reduction in the activity of a secreted cysteine protease and streptokinase, and an altered immunoglobulin and fibrinogen-binding phenotype. The site of insertion of Tn917 into the chromosome and the surrounding sequence, the pel region (pleiotropic effect locus), was determined. Phage A25 transduction confirmed that the pleiotropic changes in phenotype could be cotransduced with Tn917. The pel region was cloned and sequenced, and the transposon was found to be inserted upstream of a single open reading frame which led to a failure to transcribe a 500-base mRNA. The loss of this transcript decreased the transcription of emm and speB genes and reduced the secretion of streptokinase. Enhanced Pel expression from a nisin-inducible plasmid resulted in increased message levels for emm in a wild-type organism. Characterization of the pel mutant provides evidence for the coordinated regulation of secreted and surface proteins and suggests the existence of a new global regulatory factor in S. pyogenes.

Li, Zhuqing; Sledjeski, Darren D.; Kreikemeyer, Bernd; Podbielski, Andreas; Boyle, Michael D. P.

1999-01-01

205

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

NASA Astrophysics Data System (ADS)

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 aircraft including an accurate estimate of aerosol optical depth. We present a sensitivity study to illustrate the merits of polarization measurements in detecting variations of ocean surface properties linked to the presence of an oil slick. In particular, the Degree of Linear Polarization (DoLP) in the glint region does not depend on the surface roughness, while is severely affected by variations in the refractive index of the ocean surface. Exploiting the RSP channel at 2250nm, where virtually all the signal is generated by the Fresnel reflection at the surface, the DoLP at any angle well into the glint region can therefore be used to detect alterations in the ocean surface. More specifically, the glint profile at this wavelength is fitted to the Cox-Munk model with a routine which can optimally estimate wind speed and direction, while taking into account aircraft attitude variations in determining the viewing geometry. The surveyed area also presents a complex mix of aerosol types. At least one major urban layer originating in the US Southeast mixes in the central portion of the flight trajectory with smoke caused by controlled burns around the damaged platform. The constrain on surface reflectance provided by the SWIR RSP channel, together with the aerosol optical depth provided by the HSRL, are used in Radiative Transfer computations to model the channels at shorter wavelengths and retrieve aerosol descriptive parameters such as aerosol size distribution and refractive index. Finally, the presence of smoke is ground for a discussion on the possibility to infer aerosol absorption. In this respect, RSP retrieval can be aided by the HSRL unique capability of measuring aerosol extinction and backscatter independently.

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

2010-12-01

206

Mesopic luminance assessed with minimum motion photometry.  

PubMed

We measured the relative contribution of rods and cones to luminance across a range of photopic, mesopic, and scotopic adaptation levels and at various retinal eccentricities. We isolated the luminance channel by setting motion-based luminance nulls (minimum motion photometry) using annular stimuli. Luminance nulls between differently colored stimuli require equality in a weighted sum of rod and cone excitations. The relative cone weight increases smoothly from the scotopic range, where rods dominate, to photopic levels, where rod influence becomes negligible. The change from rod to cone vision does not occur uniformly over the visual field. The more peripheral the stimulus location, the higher is the light level required for cones to participate strongly. The relative cone contribution can be described by a sigmoid function of intensity, with two parameters that each depend on the eccentricity and spatial frequency of the stimulus. One parameter determines the "meso-mesopic" luminance--the center of the mesopic range, at which rod and cone contributions are balanced. This increases with eccentricity, reflecting an increase in the meso-mesopic luminance from 0.04 scotopic cd/m(2) at 2° eccentricity to 0.44 scotopic cd/m(2) at 18°. The second parameter represents the slope of the log-log threshold-versus-intensity curve (TVI curve) for rod vision. This parameter inversely scales the width of the mesopic range and increases only slightly with eccentricity (from 0.73 at 2° to 0.78 for vision at 18° off-axis). PMID:21868482

Raphael, Sabine; MacLeod, Donald I A

2011-08-25

207

HST BVI photometry of Triton and Proteus  

NASA Astrophysics Data System (ADS)

BVI photometry of Triton and Proteus was derived from HST images taken in 1997. The VEGAMAG photometric technique was used. Triton was found to be brighter by a few percent than observations of the 1970's and 1980's, as expected due to the increasingly greater exposure of the bright south polar region. The leading side was also found to be brighter than the trailing side by 0.09 mag in all filters—50% larger than reported by Franz [Franz, O.G., 1981. Icarus 45, 602 606]. Contrary to our previous results [Pascu, D., et al., 1998. Bull. Am. Astron. Soc. 30, 1101], we found no episodic reddening. Our previous conclusions were based on an inaccurate early version of the Charge Transfer Efficiency (CTE) correction. The present result limits the start of the reddening event reported by Hicks and Buratti [Hicks, M.D., Buratti, B.J., 2004. Icarus 171, 210 218]. Our (B V) result of 0.70±0.01 supports the global blueing described by Buratti et al. [Buratti, B.J., Goguen, J.D., Gibson, J., Mosher, J., 1994. Icarus 110, 303 314]. Our observations of July 1997 agree with the Voyager results and are among the bluest colors seen. We found Proteus somewhat brighter than earlier studies, but in good agreement with the recent value given by Karkoschka [Karkoschka, E., 2003. Icarus 162, 400 407]. A leading/trailing brightness asymmetry was detected for Proteus, with the leading side 0.1 mag brighter. The unique differences in action of the endogenic and exogenic processes on Triton and Proteus provides an opportunity to separate the endogenic and exogenic effects on Triton.

Pascu, Dan; Storrs, Alex D.; Wells, Eddie N.; Hershey, John L.; Rohde, James R.; Seidelmann, P. Kenneth; Currie, Douglas G.

2006-12-01

208

Investigating the Stellar Populations of Disk Galaxies with Optical and Near-IR Photometry  

NASA Astrophysics Data System (ADS)

We investigate the relative stellar populations of ~ 20 nearby field spiral galaxies by use of optical (UBV) and near-infrared (JHK) imaging. Preliminary work using the RC3 and Longo et al (1988) shows a correlation in H-band surface brightness with morphology, which motivates this study. Near-infrared imaging has been taken to confirm this trend. Bulge/disk decompositions are used in order to compare multiwavelength photometry of both bulge and disk components to stellar evolutionary models. This will determine relative ages of these components as a function of morphological type.

Bergmann, S.; Marcum, P. M.; Fanelli, M. N.

1998-12-01

209

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

PubMed

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

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

2012-03-05

210

Using SysRem as an Alternative Photometry Technique  

NASA Astrophysics Data System (ADS)

In SysRem, a statistical photometric algorithm for the search for new variable objects (Tamuz et al. 2005; Mazeh et al. 2007), the correction for systematic errors for star i on frame j is expressed as the product of two coefficients, a_j and c_i. SysRem introduces some distortion to the light curves, because unknown variations of variable objects influence c_i and a_j. Shporer et al. (2007) applied SysRem for photometry of a known star with transiting planet, WASP-1b. To minimize the influence of target's variability, only the comparison stars were used for finding a_j; then c_t for the target was determined by minimizing the residuals from the best fitting model of the transit. We investigated further the possibility of using modified SysRem for precise photometry of known targets. Here we report on the results obtained with a version similar to that used by Shporer et al. (2007, hereafter ``SysRem-ph''). The target was a constant V = 11.12 star from Landolt cluster SA98 (Landolt 1992). Observations were performed on the 0.6-m MMO reflector with the Princeton Instruments E2V, 512× 512, CCD camera, on two nights, with filters V (74 frames) and I (76 frames), with 90 s and 40 s exposures per frame, respectively. The reductions were made by JW and GW. JW compared SysRem-ph with the ``grey'' differential photometry (in which the differences in colors and positions of stars are not taken into account) and with the regular SysRem, and GW - the results of ``grey'' and ``color'' differential photometry (Hardie 1962). Eight comparison stars were used by JW and 12 by GW. The results for the four data sets can be summarized as follows: (1) Regular SysRem produced standard deviations (STDEV) of 3-5 mmag, close to the predicted photon noise (? 4 mmag); (2) SysRem-ph gave larger STDEV than regular SysRem (by 0.8-0.9 mmag) but smaller than ``grey'' photometry (by 0.5-1.6 mmag); and (3) ``Color'' differential photometry was better than ``grey'' photometry by 1-2 mmag. We conclude that for one-color photometry of variable objects with identifiable periods of constancy, SysRem-ph can be a good alternative to the traditional ``grey'' differential photometry. The higher precision of SysRem-ph is due to the capability of SysRem to account for the differences in color and position of the involved stars, without prior knowledge of these differences (Mazeh et al. 2007).

Marshall, S.; Williams, J.; Mazeh, T.; Walker, G.; Strelnitski, V.

2010-02-01

211

The Presence of VEGF Receptors on the Luminal Surface of Endothelial Cells Affects VEGF Distribution and VEGF Signaling  

PubMed Central

Vascular endothelial growth factor (VEGF) is a potent cytokine that binds to specific receptors on the endothelial cells lining blood vessels. The signaling cascade triggered eventually leads to the formation of new capillaries, a process called angiogenesis. Distributions of VEGF receptors and VEGF ligands are therefore crucial determinants of angiogenic events and, to our knowledge, no quantification of abluminal vs. luminal receptors has been performed. We formulate a molecular-based compartment model to investigate the VEGF distribution in blood and tissue in humans and show that such quantification would lead to new insights on angiogenesis and VEGF-dependent diseases. Our multiscale model includes two major isoforms of VEGF (VEGF121 and VEGF165), as well as their receptors (VEGFR1 and VEGFR2) and the non-signaling co-receptor neuropilin-1 (NRP1). VEGF can be transported between tissue and blood via transendothelial permeability and the lymphatics. VEGF receptors are located on both the luminal and abluminal sides of the endothelial cells. In this study, we analyze the effects of the VEGF receptor localization on the endothelial cells as well as of the lymphatic transport. We show that the VEGF distribution is affected by the luminal receptor density. We predict that the receptor signaling occurs mostly on the abluminal endothelial surface, assuming that VEGF is secreted by parenchymal cells. However, for a low abluminal but high luminal receptor density, VEGF binds predominantly to VEGFR1 on the abluminal surface and VEGFR2 on the luminal surface. Such findings would be pertinent to pathological conditions and therapies related to VEGF receptor imbalance and overexpression on the endothelial cells and will hopefully encourage experimental receptor quantification for both luminal and abluminal surfaces on endothelial cells.

Stefanini, Marianne O.; Wu, Florence T. H.; Mac Gabhann, Feilim; Popel, Aleksander S.

2009-01-01

212

Near-IR Photometry of Nova Del 2013  

NASA Astrophysics Data System (ADS)

Subjects: Infra-Red, Nova We report Near-IR photometry of Nova Del 2013 taken with the 0.76-m infrared telescope at the University of Minnesota's O'Brien Observatory (Marine on St. Croix, Minnesota, USA). RIJHKLM photometry were obtained on August 21.17 and 23.13 UT using an AsSi bolometer. Vega (alpha Lyrae) was used as the standard star. Our photometry show: August 21.17 UT: R = 5.1 +/- 0.1, I = 4.6 +/- 0.1, J = 4.6 +/- 0.1, H = 4.1 +/- 0.1, K = 3.9 +/- 0.1, L = 2.7 +/- 0.2, M = +2.2 +/- 0.2.

Cass, C. A.; Carlon, L. R.; Corgan, T. D.; Dykhoff, A. D.; Gehrz, D. R.; Shenoy, P. D.

2013-08-01

213

Factors affecting the potassium concentration at the mucosal surface of the proximal and the distal colon of guinea pig.  

PubMed

K+ concentrations were measured in vitro with K+ sensitive microelectrodes in the microclimate at the luminal cell surface of the colon of guinea pigs. The serosal K+ concentration was mostly 5.4 mmol/1, the mucosal K+ concentrations were changed (0, 5, 50, or 70 mmol/l). Under control conditions K+ concentrations in the microclimate of the proximal colon were also low (6-9 mmol/l) and rather independent from K+ concentrations in the bulk luminal solution. In the distal colon K+ concentrations in the microclimate increased from 3.7 mmol/l when no K+ was in the luminal solution, up to 22 mmol/l when the mucosal K+ concentrations was 70 mmol/l. Attempts to decrease K+ conductance of the apical membrane with Ba++, to impair K+ transport with ouabain and to increase the paracellular shunt with deoxycholic acid did not affect K+ concentrations in the microclimate of the proximal colon but decreased K+ concentrations in the distal colon. When valinomycin or triaminopyrimidine were added to the mucosal solution at high K+ concentrations in the luminal solutions the K+ concentration in the microclimate was raised. At low luminal K+ concentrations valinomycin had no effect, triaminopyrimidine significantly diminished K+ concentrations at the cell surface. Regional differences in paracellular shunt conductance and in the preepithelial diffusion barrier are thought to be responsible for the observed differences between the proximal and the distal colon. Obviously, however, further unknown mechanisms have to be involved. PMID:2108077

Kück-Biere, U; von Engelhardt, W

1990-01-01

214

Photometry of UCM galaxies (Perez-Gonzalez+, 2000)  

NASA Astrophysics Data System (ADS)

We present Johnson B CCD photometry for the whole sample of galaxies of the Universidad Complutense de Madrid (UCM) Survey Lists I and II (Cat. and ). They constitute a well-defined and complete sample of galaxies in the Local Universe with active star formation. The data refer to 191 S0 to Irr galaxies at an averaged redshift of 0.027, and complement the already published Gunn r, J and K photometries. (B-r) colours are also computed. (2 data files).

Perez-Gonzalez, P. G.; Zamorano, J.; Gallego, J.; Gil de Paz, A.

1999-11-01

215

Automated photographic photometry of stars in globular clusters  

NASA Astrophysics Data System (ADS)

An automatic method for stellar photometry in crowded fields is presented. The reduction procedure, based on a multicomponent fitting routine, applies to PDS scans of a photographic plate and gives accurate magnitudes of all the objects with a detectable maximum (the estimated internal error is ? ? 0.02 m). The extended objects (galaxies or extremely blended stellar images) are recognized and passed to an interactive procedure. An application to the photometry of 2344 stars in the field of the globular cluster NGC 2808 is also shown.

Buonanno, R.; Buscema, G.; Corsi, C. E.; Ferraro, I.; Iannicola, G.

1983-10-01

216

Retention and rainfastness of mancozeb as affected by physicochemical characteristics of adaxial apple leaf surface after enhanced UV-B radiation  

Microsoft Academic Search

It is not clear so far whether alteration of leaf micromorphology and surface wax chemistry due to the impact of environmental factors, such as UV-B radiation, affects retention and rainfastness of applied pesticide solutions. In this study; UV-B treated and untreated adaxial leaf surfaces of apple seedlings (Malus domestica Borkh.) were characterized in terms of chemical composition, micromorphological fine structure,

Katja Bringe; Mauricio Hunsche; Michaela Schmitz-Eiberger; Georg Noga

2007-01-01

217

Photometry of Cepheids in Magellanic Clouds (Moffett+ 1998)  

NASA Astrophysics Data System (ADS)

In this paper we present the new photometric data, demonstrate the consistency among the data obtained from CCD and aperture photometry, and determine improved periods for all of the variables. In follow-up papers we will use these observations to determine individual Cepheid distances and radii from the visual surface brightness technique and also from the infrared surface brightness technique (Welch 1994AJ....108.1421W; Fouque & Gieren 1997A&A...320..799F). Table 1 gives our final photometric results. All entries in Table 1 having B magnitudes are CCD observations (CTIO), and the ones lacking B magnitudes are photoelectric observations (ESO). The uncertainties in the CCD results are dominated by the uncertainty in the aperture correction. The standard deviation in the comparison stars on a particular image is typically +/-0.004 mag and always less than +/-0.01 mag. The aperture correction to the zero point of each frame is estimated to be better than +/-0.01 mag. We adopt +/-0.01 mag as the typical uncertainty in all magnitudes. For the photoelectric observations, we inferred the uncertainties from scatter in the observations of the Cepheids themselves, finding +/-0.010 mag in V and +/-0.012 mag in R and I. We combined our new photometry with existing photoelectric photometry from the literature to determine a new period for each Cepheid. This was greatly aided by the McMaster Cepheid Data Archive maintained by Doug Welch at http://www.physics.mcmaster.ca/Cepheid/. (The data reported here will be added to the McMaster archive.) Periods were found using an algorithm due to T. Deeming given in Bopp et al. (1970MNRAS.147..355B) and are listed in Table 2. The uncertainty of each period is reflected in the number of digits given in the table. For most of the Cepheids in our sample, the new periods lead to excellent light curves of very low scatter, which indicates that the periods for these variables are both correct and stable over the time of our observations. For the Cepheids with comments in Table 2, however, the periods appear to be changing in time. The existing data set is insufficient to describe fully the nature of these period changes. Also in Table 2 we compare our intensity mean V magnitudes with those from the literature, as represented by an extensive, private data base maintained by J.A.R. Caldwell (1997, private communication). The intensity means were determined from Fourier fits to the (intensity-converted) light curves. The agreement is very good. The mean difference between the data sets is -0.005 mag, and the standard deviation is 0.019 mag. For Cepheids with the best new data, we have listed a value to 0.001 mag, while for stars with less complete light curves, the values are listed to 0.01 mag only. Table 2: New Periods and Mean V Magnitudes for Magellanic Cloud Cepheids Period V(new) V(SAAO) Cepheid (days) Comment (mag) (mag) --------------------------------------------------------- LMC --------------------------------------------------------- HV 879... 36.827 13.332 13.35 HV 883... 133.585 12.14 HV 899... 31.0461 13.433 13.43 HV 900... 47.5085 12.766 12.78 HV 909... 37.5654 12.774 12.74 HV 2257... 39.3699 13.031 13.06 HV 2338... 42.1944 12.759 12.78 HV 2447... 118.3115 11.990 12.00 HV 2827... 78.77 Variable? 12.280 12.30 HV 2864... 10.9845 14.651 14.65 HV 2883... 108.968 12.41 HV 5497... 98.975 Variable? 11.92 11.94 HV 12815.. 26.1157 13.506 13.48 HV 12816.. 9.1089 14.500 14.52 --------------------------------------------------------- SMC --------------------------------------------------------- HV 821... 127.314 Variable? 11.93 11.94 HV 824... 65.8635 12.36 12.37 HV 829... 85.199 Variable? 11.93 11.91 HV 834... 73.639 Variable? 12.21 12.21 HV 837... 42.6954 13.24 13.23 HV 1338... 8.49503 15.12 15.16 HV 1365... 12.4117 Variable? 15.04 15.02 HV 11157.. 69.0872 12.93 12.94 (1 data file).

Moffett, T. J.; Gieren, W. P.; Barnes, T. G., III; Gomez, M.

2000-09-01

218

Processes affecting the transport of Cryptosporidium parvum and other persistent pathogens in surface- and ground-waters  

NASA Astrophysics Data System (ADS)

Waterborne diseases are transmitted through numerous environmental pathways, and their migration is strongly mediated by interaction with a wide variety of sediments and other natural materials during transport. Here we provide an overview of factors that affect the fate of persistent water-borne pathogens, focusing particularly on the zoonotic pathogen Cryptosporidium parvum as an example. While individual microbial cells are both small and have low specific gravity, suggesting that they should be highly mobile and remain suspended for long periods of time, attachment to a variety of background materials can substantially reduce pathogen mobility. Cryptosporidium oocysts readily associate with both inorganic and organic particles, resulting in the formation of aggregates. This process tends to increase the effective settling velocity of C. parvum in surface waters. Similarly, pathogens readily become associated with the solid matrix during transport in groundwater, resulting in removal by filtration. However, this process is reversible with C. parvum, resulting in a slow long-term release following the initial deposition. Pathogens also become associated with biofilms, which are surface-attached communities of microorganisms in a gelatinous matrix. The presence of biofilms increases the immobilization and retention of Cryptosporidium on solid surfaces. All of these processes influence pathogen transmission in surface waters such as rivers and water-supply canals. In these environments, pathogens can be immobilized by deposition into stable sediment beds by a combination of gravitational sedimentation and advection into pore waters followed by subsurface filtration. Association with background suspended matter tends to increase pathogen deposition by sedimentation, and the presence of benthic (sedimentary) biofilms also tends to increase pathogen retention. For pathogens that remain viable for long periods of time in natural aquatic systems, as is the case with Cryptosporidium and other cyst-and spore-forming organisms, then the sediments and sedimentary biofilms become an environmental reservoir of pathogens. Cysts retained in biofilms appear to be relatively difficult to resuspend, but slow, long-term biological release and high-flow events that mobilize streambed sediments both deliver pathogens into transport.

Packman, A. I.; Lau, B. L.; Harter, T.; Atwill, E. R.

2007-12-01

219

Combined Photometry and Spectroscopy of Globular Cluster Tidal Streams  

Microsoft Academic Search

Globular cluster tidal streams are of interest for what they can tell us of the dynamical evolution of the clusters and our Galaxy. Recent studies have used photometric and statistical subtraction methods to attempt to separate potential streams from the field stars that contaminate the samples. We chose instead to use photometry to select blue stars that match the horizontal

W. L. Powell; R. Wilhelm; A. McWilliam; A. Westfall; A. Lauchner

2005-01-01

220

Two-Color Photoelectric Photometry of the Earthshine  

Microsoft Academic Search

digcult to assess to what extent this value varies with changing meteorological conditions and differing observing locations. Ranjon's observations were carried out only in France, and both he and Fritz [1949] have indicated the benefits of photometry from other stations. Wildey [1964], although beset by various uncertainties, has obtained from a photometer carried in Mariner 2 results that differ from

F. A. Franklin

1967-01-01

221

Photometry of Restored Full-Disk Solar Images  

NASA Astrophysics Data System (ADS)

The San Fernando Observatory (SFO) Cartesian Full Disk Telescope (CFDT) has been taking full-disk 512 square photometric images of the Sun through a 100 Angstroms bandpass red filter since 1985, and through a 10 Angstroms bandpass K-line filter since 1989. We have recently begun a project to attempt to remove the effects of atmospheric blurring and scattered light on the photometry of these images. Specifically, we are fitting the convolution of a limb darkening profile expansion and a model point spread function (PSF) to the radial profiles of SFO CFDT images, using a technique similar to that of Toner and Jeffries (Ap. J. 1996, submitted) to remove the PSF from the images. The blurring-free limb darkening profile is the sum of an expansion in orthogonal (Legendre) polynomials, and the PSF model is the sum of three Gaussian components plus a Lorentzian, normalized so that its integral over the sky is unity. Tests with artificially generated images with sunspots show that we can recover the sunspot photometric quantities with excellent results. Comparison of the original and restored photometry from eight actual red images taken hourly also show that correlations between the PSF and the photometry disappear after the restoration. We have been less successful at recovery of facular photometry in the K line images, and are continuing to investigate this. We will present details of our fitting procedure and results. This project was partly supported by NSF Grant ATM-9115111 and NASA grant NAGW-3017.

Walton, S. R.; Preminger, D. G.; Toner, C. G.

1996-05-01

222

Flaring on RS CVn systems: Results from EUVE Photometry  

Microsoft Academic Search

We present broadband EUV photometry for a sample of RS CVn systems observed with the Deep Survey Spectrometer and Right Angle Program (RAP) Scanners on the Extreme Ultraviolet Explorer (EUVE). We have developed robust data analysis and light curve software for the interpretation of these data. Large-scale flaring activity is seen on 15 of the 18 systems studied. These binaries

R. A. Osten; A. Brown; T. R. Ayres

1998-01-01

223

General Catalog of Photometry of Galaxies (Longo+ 1983)  

Microsoft Academic Search

Details of the integrated photometry of galaxies in the UBV system (generally through circular apertures centered at the nucleus) published prior to 1963 were given in three appendices to the (First) Reference Catalogue of Bright Galaxies (RCBG = RC1). The publication of an updated listing in the Second Reference Catalogue (RC2) has been requested since then. The present catalogue contains

G. Longo; A. de Vaucouleurs

1994-01-01

224

Photometry of Three Fields in the Orion Nebula Cluster  

Microsoft Academic Search

We have initiated a program of repeated R and I photometry of three fields in the Orion Nebula Cluster. Our observations were performed at the Lowell Observatory 31-inch telescope which, under an agreement with Northern Arizona University and the NURO Consortium, is operated 60% of the time as the National Undergraduate Research Observatory. These three fields and several others covering

K. L. McFarland; R. J. Boyle; B. W. Taylor; E. B. Zamkoff

1997-01-01

225

JHK photometry of carbon stars and their effective temperature  

Microsoft Academic Search

Infrared photometry in the J, H, and K bands of 24 carbon stars from Stephenson's (1973) General Catalog of Carbon Stars (GCCS) is presented. The observations were carried out on four nights in late November 1982, using the near-infrared photometer attached to the Yunnan 1-meter telescope. The photometric system constants used in the observations are given in a table. The

Heng Gao; Pei-Sheng Chen; Yun Zhang

1985-01-01

226

BVRI Photometry of Blazar PKS 0507+179  

NASA Astrophysics Data System (ADS)

We present optical broadband photometry (Bessel BVRI) in response of recent reports (ATel #4424, #4528, #4531) showing increased brightening of blazar PKS 0507+179. The images are obtained with the 50/70 cm Schmidt telescope at NAO Rozhen, Bulgaria. The available magnitudes are:

Ovcharov, E.; Metodieva, Y.; Kurtenkov, A.; Dineva, E.; Bogdanov, K.; Teodossiev, S.; Bozhilov, V.

2012-11-01

227

HST photometry of Sculptor group dwarf galaxies (Lianou+, 2013)  

NASA Astrophysics Data System (ADS)

Position and photometry for the resolved stars of five dwarf galaxies in the Sculptor Group. The dwarf galaxies are: ESO540-G030; ESO540-G032; ESO294-G010; ESO410-G005; SCL-DE1. The catalogue includes only those stars in which all selection criteria described in the companion paper were applied. (6 data files).

Lianou, S.; Grebel, E. K.; da Costa, G. S.; Rejkuba, M.; Jerjen, H.; Koch, A.

2013-05-01

228

Iontophoresis and Flame Photometry: A Hybrid Interdisciplinary Experiment  

ERIC Educational Resources Information Center

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…

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

2010-01-01

229

A new look at photometry of the Moon  

Microsoft Academic Search

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° < alpha < 50°, we test two different physical models, macroscopic roughness and multiple scattering between regolith particles, for their

Jay D. Goguen; Thomas C. Stone; Hugh H. Kieffer; Bonnie J. Buratti

2010-01-01

230

VI photometry of 5 open clusters (Carraro+, 2007)  

Microsoft Academic Search

The stellar populations in the outer Galactic disk are a subject of wide interest nowadays. To contribute to a better picture of this part of the Galaxy, we have studied the nature of five marginally investigated star clusters (Collinder 74, Berkeley 27, Haffner 8, NGC 2509, and VdB-Hagen4) by means of accurate CCD photometry in the V and I passbands.

G. Carraro; E. Costa

2007-01-01

231

Characterizing New Eclipsing Binaries Identified from STEREO Photometry  

NASA Astrophysics Data System (ADS)

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).

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

2012-04-01

232

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

Microsoft Academic Search

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

P. Cinzano

2003-01-01

233

JHK Photometry of CN-Rich Field Giants. Abstract Only.  

National Technical Information Service (NTIS)

Infrared JHK photometry was obtained for a sample of CN-rich Population I field giants. On average, the CN-rich giants show a modest color separation from more typical field giants of near solar abundance in the J-H, H-K two-color diagram. Many of the CN ...

G. H. Smith

1987-01-01

234

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

USGS Publications Warehouse

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.

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

2008-01-01

235

SPA, "The Stellar Photometry Assistant", a New Software Package Specializing in High Speed Photometry of White Dwarfs  

NASA Astrophysics Data System (ADS)

SPA, "The Stellar Photometry Assistant", is a new program for photometry reduction and analysis slated for initial release in early 2008. Development was fueled by high speed photometry of white dwarfs, mainly EC20058-5235, a pulsating DB white dwarf. The stability of EC20058-5235's primary mode, along with the relatively short timescales of DB cooling may allow a measurement of dP/dt. EC20058-5235 has 2 companions of comparable magnitude within 5'', which adds significant noise to simple aperture photometry. This, combined with the relatively steep learning curve of IRAF, and IRAF like tools sparked the beginning of SPA. SPA combines powerful, proven, methods with an easy to use interface. Currently SPA is written in MATLAB, but future plans include a cross platform stand alone application. SPA tackles many issues such as auto-tracking jumps in star location and crowded field reduction. SPA will also provide easy to use tools for viewing and manipulating data. The interface is intuitive and is suitable for both amateur and professorial astronomers. SPA is being developed by The University of Delaware in collaboration with the Delaware Asteroseismic Research Center (DARC) and the Mt. Cuba Astronomical Observatory.

Dalessio, James; Kanaan, A.; Provencal, J.

2007-12-01

236

Characterizing Young Brown Dwarfs Using Synthetic Photometry and Expanded Spectral Energy Distributions  

NASA Astrophysics Data System (ADS)

Brown dwarfs cool, shrink and fade with time; therefore, older and more massive objects can have the same optical spectral types as younger, less massive brown dwarfs. Ambiguity in their near-infrared spectra further obfuscates crucial physical parameters such as effective temperature, surface gravity, metallicity, and dust and clouds. We attempt to disentangle these parameters by calculating a suite of synthetic colors from PHOENIX model atmospheres, using confirmed young brown dwarfs as benchmark objects to identify colors sensitive to surface gravity. We also construct nearly complete spectral energy distributions (SEDs) by combining WISE mid-infrared photometry with our extensive database of optical and near-infrared spectra and parallaxes. With the extended SEDs of known young objects and increased wavelength baseline of diagnostic colors we will be able to identify new young candidates to expand our sample of young brown dwarfs and understand their atmospheric properties.

Filippazzo, Joe; Rice, E. L.; Cruz, K. L.; Faherty, J.; BDNYC

2013-01-01

237

Lunar Photometry and Composition of Ejecta Terrains  

Microsoft Academic Search

One scientific goal of the AMIE experiment to fly onboard the SMART-1 mission is to investigate, at low polar orbit, the South Pole regions of the Moon. The AMIE camera will observe the surface in nadir direction within a large phase angle interval, thus providing photometric investigation of selected regions, in particular the South Pole- Aitken basin. The view is

V. V. Shevchenko; S. G. Pugacheva; P. Pinet; S. Chevrel; Y. Daydou

2002-01-01

238

Prolonged mechanical unloading affects cardiomyocyte excitation-contraction coupling, transverse-tubule structure, and the cell surface  

PubMed Central

Prolonged mechanical unloading (UN) of the heart is associated with detrimental changes to the structure and function of cardiomyocytes. The mechanisms underlying these changes are unknown. In this study, we report the influence of UN on excitation-contraction coupling, Ca2+-induced Ca2+ release (CICR) in particular, and transverse (t)-tubule structure. UN was induced in male Lewis rat hearts by heterotopic abdominal heart transplantation. Left ventricular cardiomyocytes were isolated from the transplanted hearts after 4 wk and studied using whole-cell patch clamping, confocal microscopy, and scanning ion conductance microscopy (SICM). Recipient hearts were used as control (C). UN reduced the volume of cardiomyocytes by 56.5% compared with C (UN, n=90; C, n=59; P<0.001). The variance of time-to-peak of the Ca2+ transients was significantly increased in unloaded cardiomyocytes (UN 227.4±24.9 ms2, n=42 vs. C 157.8±18.0 ms2, n=40; P<0.05). UN did not alter the action potential morphology or whole-cell L-type Ca2+ current compared with C, but caused a significantly higher Ca2+ spark frequency (UN 3.718±0.85 events/100 ?m/s, n=47 vs. C 0.908±0.186 events/100 ?m/s, n=45; P<0.05). Confocal studies showed irregular distribution of the t tubules (power of the normal t-tubule frequency: UN 8.13±1.12×105, n=57 vs. C 20.60± 3.174×105, n=56; P<0.001) and SICM studies revealed a profound disruption to the openings of the t tubules and the cell surface in unloaded cardiomyocytes. We show that UN leads to a functional uncoupling of the CICR process and identify disruption of the t-tubule-sarcoplasmic reticulum interaction as a possible mechanism.—Ibrahim, M., Al Masri, A., Navaratnarajah, M., Siedlecka, U., Soppa, G. K., Moshkov, A., Abou Al-Saud, S., Gorelik, J., Yacoub, M. H., Terracciano, C. M. N. Prolonged mechanical unloading affects cardiomyocyte excitation-contraction coupling, transverse-tubule structure, and the cell surface.

Ibrahim, Michael; Al Masri, Abeer; Navaratnarajah, Manoraj; Siedlecka, Urszula; Soppa, Gopal K.; Moshkov, Alexey; Al-Saud, Sara Abou; Gorelik, Julia; Yacoub, Magdi H.; Terracciano, Cesare M. N.

2010-01-01

239

Pneumococcal Surface Protein A does not affect the immune responses to a combined diphtheria tetanus and pertussis vaccine in mice.  

PubMed

The Pneumococcal Surface Protein A (PspA) is a promising candidate for the composition of a protein vaccine against Streptococcus pneumoniae. We have previously shown that the whole cell Bordetella pertussis vaccine (wP) is a good adjuvant to PspA, inducing protective responses against pneumococcal infection in mice. In Brazil, wP is administered to children, formulated with diphtheria and tetanus toxoids (DTPw) and aluminum hydroxide (alum) as adjuvant. A single subcutaneous dose of PspA5-DTPlow (a formulation containing PspA from clade 5 and a new generation DTPw, containing low levels of B. pertussis LPS and Alum) induced high levels of systemic anti-PspA5 antibodies in mice and conferred protection against respiratory lethal challenges with two different pneumococcal strains. Here we evaluate the mucosal immune responses against PspA5 as well as the immune responses against the DTP antigens in mice vaccinated with PspA5-DTPlow. Subcutaneous immunization of mice with PspA5-DTPlow induced high levels of anti-PspA5 IgG in the airways but no IgA. In addition, no differences in the influx of cells to the respiratory mucosa, after the challenge, were observed in vaccinated mice, when compared with control mice. The levels of circulating anti-pertussis, -tetanus and -diphtheria antibodies were equivalent in mice vaccinated with DTPlow or PspA5-DTPlow. Antibodies induced by DTPlow or PspA5-DTPlow showed similar ability to neutralize the cytotoxic effects of the diphtheria toxin on Vero cells. Furthermore, combination with PspA5 did not affect protection against B. pertussis and tetanus toxin challenges in mice. Our results support the proposal for a combined PspA-DTP vaccine. PMID:23541622

Lima, Fernanda A; Miyaji, Eliane N; Quintilio, Wagner; Raw, Isaias; Ho, Paulo L; Oliveira, Maria Leonor S

2013-03-26

240

Disk-Integrated Photometry of 433 Eros  

Microsoft Academic Search

Analysis of the disk-integrated solar phase curve of 433 Eros, as derived from ground-based telescopic and NEAR Shoemaker spacecraft measurements, shows that Eros's surface properties are typical of average S-type asteroids. Eros displays the same single-particle scattering characteristics and porosity vs theoretical grain size relationships as typical S-asteroids, as does Ida. Eros's single-scattering albedo, however, is higher. The geometric albedo

D. L. Domingue; M. Robinson; B. Carcich; J. Joseph; P. Thomas; B. E. Clark

2002-01-01

241

Use of a 3D laser scan technique to compare the surface geometry of the medial coronoid process in dogs affected with medial compartment disease with unaffected controls.  

PubMed

Subchondral bone surface geometry of the medial coronoid process was examined in 20 grossly normal elbow joints of adult German Shepherd dogs (GSDs) and compared with results obtained from 10 joints of adult GSDs and 12 joints of adult Rottweilers affected with bilateral fragmentation of the medial coronoid process (FMCP). Additionally, seven dogs (4 GSDs and 3 Rottweilers) with unilateral FMCP were investigated. The subchondral contour of the ulnar trochlear notch was digitised to obtain the 3D coordinates of its surface points. Geometry was investigated in two defined section planes along the longitudinal and transverse axes of the medial coronoid process. The coordinates of the surface points in the section planes were normalised along one axis and geometry was estimated by the position of the surface points along its third coordinate and by calculation of the angle of inclination of the medial coronoid process. Subchondral bone surface geometry was not related to the type of fragmentation (i.e. single sagittal versus multiple sagittal or transverse fragmentation). No differences were noted when comparing joints of dogs affected unilaterally with FMCP and their contralateral normal joints. In addition, no differences in geometry were seen between GSDs affected with fragmentation and normal GSDs. The most evident differences were found between Rottweilers affected with FMCP and normal GSDs as well as FMCP affected GSDs. The results suggest that subchondral bone geometry (geometric incongruity) plays no role in the development of FMCP. Geometric differences between breeds were more prevalent than differences between normal joints and those affected with FMCP within one breed. PMID:19647455

Breit, Sabine; Pfeiffer, Kristina; Pichler, Reinhard

2009-07-31

242

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...

243

Infrared photometry and spectroscopy in L1641N (Galfalk+, 2008)  

NASA Astrophysics Data System (ADS)

Space-based photometry of sources in our L1641N catalogue, with Spitzer (3.6, 4.5, 5.8, and 8.0 microns) and ISO satellite (6.7 and 14.3 microns), and ground-based photometry with 2.56m Nordic Optical Telescope (NOT) in JHks. Optical spectra (5780-8340{AA}) of Young Stellar Object (YSO) candidates in our L1641N source catalogue. The spectra were taken with the 2.56m Nordic Optical Telescope (NOT) Dec 02-04 2003 and Jan 08-10 2005 (added from both epochs). Each spectrum is contained in a 2052x2 FITS file. The first row in each file is the wavelength [{AA}]. The second row in each file is the flux [erg/s/cm2/{AA}] (3 data files).

Galfalk, M.; Olofsson, G.

2008-05-01

244

UBV photometry of FK Com and HD 199178 (Panov+, 2007)  

NASA Astrophysics Data System (ADS)

We report previously unpublished photometric observations of FK Com (1990-2005) and HD 199178 (1991-2004). The observations have been carried out with the 60cm telescope of the Rozhen National Astronomical Observatory (Bulgaria). Observations contain measurements in the Johnson U,B and V bands. The observations are differential. For FK Com, the differential photometry is with respect to HD 117567. For HD 199178, the differential photometry is with respect to HD 199206. Table 2a,b contains a summary of subsets for FK Com and HD 199178, respectively. Table 3a,b contains UBV data for FK Com and HD 199178, respectively, obtained at Rozhen Observatory. Missing data are substituted with 99.000. Table 5a,b contains results of light-curve modelling for FK Com and HD 199178, respectively. (6 data files).

Panov, K.; Dimitrov, D.

2007-03-01

245

High Precision Differential Photometry with CCDs: A Brief History  

NASA Astrophysics Data System (ADS)

I present a brief history of the hunt for high photometric precision using CCDs in astronomy. CCDs were invented in 1969 and only 7 years later they started to appear at the major observatories of the time. The next 10 years constituted a steep learning curve for astronomers as they developed an understanding of CCDs as instruments and analysis techniques for use with digital images. In 1985, differential photometry with CCDs began producing light curves with precisions near 0.01 magnitude. By 2008, ground-based telescopes armed with CCDs and using differential techniques consistently can provide photometric precisions of 1 millimagnitude or better. The challenge now is to continue to improve the photometry using new types of CCD detectors and other advanced digital imagers.

Howell, Steve B.

246

Photometry of low-mass stars in Praesepe  

NASA Astrophysics Data System (ADS)

The results of a program of BVRI photometry of a set of relatively faint stars in the Praesepe cluster are reported. The program stars were selected to be high-probability members of the cluster based on a new proper-motion study by Jones and Cudworth (1982). Those membership identifications appear to have been quite accurate, since all but two of the stars observed have colors and magnitudes consistent with cluster membership. The new photometry, combined with previous data from Upgren, Weis, and DeLuca (1979) and Weis (1981) are used to show that the intrinsic width of the Praesepe main sequence remains quite narrow within 0.15 magnitude up to at least magnitude 10.5.

Stauffer, J.

1982-08-01

247

Millimeter-to-Far-Infrared Photometry of Cygnus A  

NASA Astrophysics Data System (ADS)

We present precision photometry and imaging of the core and two radio lobes of the galaxy Cygnus A at a wavelength of 2 millimeters, taken using the GISMO camera at the IRAM 30m telescope. We also present new 350 micron photometry using the SHARC-II camera at the CSO, archival Spitzer data, and WISE data, all with the aim of producing a precision spectral energy distribution of the synchrotron emission from the two radio lobes along with a single-dish size of the synchrotron-emitting regions. Using a sophisticated mapping approach and with attention to an accurate beamwidth measurement, we are able to determine that the two lobes have an effective emission scale of around 9+/-0.5 arcseconds, and are therefore roughly 10kpc in scale.

Benford, Dominic J.; Staguhn, J.; Kovacs, A.; Sharp, E.; Maher, S.

2013-01-01

248

Photometry of Variable Stars from Dome A, Antarctica  

NASA Astrophysics Data System (ADS)

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 deg2 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 ? Scuti, ? Doradus, and RR Lyrae variables. One variable may be a transiting exoplanet.

Wang, Lingzhi; Macri, Lucas M.; 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; Zhu, Zonghong

2011-11-01

249

Walraven Photometry of southern OB associations (de Geus+ 1990)  

NASA Astrophysics Data System (ADS)

Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars in the region of five nearby southern OB associations: Sco-Cen (Sco OB2), Ori OB1, CMa OB1, Mon OB1, and Sct OB2. Note that the tables have been prepared at Lausanne/Geneve Observatory (star names in Lausanne/Geneva system, coordinates absent) For details about the Walraven photometric system, see (1 data file).

de Geus, E. J.; Lub, J.; van de Grift, E.

1994-05-01

250

WIYN Open Cluster Study: UBVRI CCD Photometry of M34  

Microsoft Academic Search

M34 is a thoroughly studied open cluster on its way to becoming a fundamental WOCS cluster. We provide photometry of M34 in the U, B, V, R, and I filters in order to re-evaluate its fundamental properties. Observations were made on the WIYN 0.9m telescope on 17 January 2003 using a field of 20' x 20' on the S2KB CCD.

J. L. Windschitl; H. Gneiser; Constantine P. Deliyannis; A. Sarajedini; I. Platais

2004-01-01

251

Precise Photometry Mission -- Measuring Stellar Microvariability from Space  

Microsoft Academic Search

Atmospheric scintillation limits the precision attainable by ground-based photometry; this limitation is a major obstacle to progress in several fields, notably asteroseismology of Sun-like stars. A space-borne photometric telescope could operate near the shot noise limit, removing this obstacle and providing new opportunities for inquiry. As part of the program for New Mission Concepts in Astrophysics, we are studying the

T. M. Brown; W. Borucki; S. Frandsen; R. L. Gilliland; A. Jones; R. W. Noyes; T. Tarbell; R. K. Ulrich

1995-01-01

252

Using a Web Cam CCD to do V Band Photometry  

NASA Astrophysics Data System (ADS)

With the plethora of cheap web cam based CCD cameras in the market today, it seemed expedient to find out if they can be used to do photometry. An experiment was planned to determine if it was possible to do this kind of exacting measurement. Arne Henden (AAVSO) believed it would be possible to do V band photometry to 0.05 mag accuracy with a web cam CCD. Using a 6" refractor, the heart of M42 was repeatedly imaged. Theta 2 and SAO 132322 were the comparison stars and V361 Orion was the target variable. Since the 1/4 HAD CCD chip only allows for a field of 10x7 arc minutes using the 6" refractor, the number targets was limited. The RGB on the chip itself provides the filters needed for photometry. The G band pass on the chip ranges from 425-650 nm with a peak band pass at 540, V band pass is 475-645 with a peak at 525. The results indicate that a web cam CCD can be used for V band photometry. With a 10 second calibrated exposure without the Peltier cooling being engaged, the results for the 2 target stars were ± 0.18 mag. The star Theta 2 was 0.18 brighter in V than the actual measurement from the Tycho catalog. SAO 132322 was -0.012 mag dimmer than the listed Tycho measurement. Then using SAO 132322 and Theta 2 as comparison stars, V361 Orion was estimated at 7.786 magnitudes. This is inline with visual estimates received before and after this date. With more estimates of known magnitude comparison stars, a correction factor should be estimated and applied to the variable work that will make it more accurate. This correction factor should bring it close to Arne Henden's estimate of 0.05 mag accuracy.

Temple, Paul

2009-05-01

253

A new look at photometry of the Moon  

Microsoft Academic Search

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°

Jay D. Goguen; Thomas C. Stone; Hugh H. Kieffer; Bonnie J. Buratti

2010-01-01

254

Wide metal-poor binaries BVRI photometry (Zapatero Osorio+, 2004)  

NASA Astrophysics Data System (ADS)

Observing dates, differential photometry and astrometry (rho and position angle) of companion candidates around 473 nearby, low-metallicity G- to M-type stars are provided in the Table. The target stars were mainly taken from the Carney-Latham surveys. Also provided are exposure times, the FWHM of the CCD images, and the telescope used for collecting the observations. The last column contains a flag indicating whether the candidate is a confirmed physical companion. (2 data files).

Zapatero Osorio, M. R.; Martin, E. L.

2004-04-01

255

UBV photometry of V379 Cep (Harmanec+, 2007)  

NASA Astrophysics Data System (ADS)

Reduction of new spectra was carried out in the IRAF and SPEFO programs. New photometry was reduced and transformed to the standard system using the HEC22 program. Orbital elements were derived with the FOTEL program and via disentangling with the program KOREL. The final combined solution was obtained with the program PHOEBE. Some initial period searches were carried out using the phase dispersion minimalization technique. (4 data files).

Harmanec, P.; Mayer, P.; Prsa, A.; Bozic, H.; Eenens, P.; Guinan, E. F.; McCook, G.; Koubsky, P.; Ruzdjak, D.; Engle, S.; Sudar, D.; Skoda, P.; Slechta, M.; Wolf, M.; Yang, S.

2006-11-01

256

M5 (NGC5904) UBVRI photometry (Viaux+, 2013)  

NASA Astrophysics Data System (ADS)

We have carried out crowded-field, point-spread function (PSF) photometry for M5 using the DAOPHOT II/ALLFRAME suite of programs (Stetson 1987PASP...99..191S, 1994PASP..106..250S). The current corpus of observations for M5 consists of 2840 CCD images obtained during 40 observing runs on 12 telescopes over a span of 27 years. (1 data file).

Viaux, N.; Catelan, M.; Stetson, P.; Raffelt, G.; Redondo, J.; Valcarce, A.; Weiss, A.

2013-08-01

257

Blue stars with disk photometry in NGC 6611 (Guarcello+, 2010)  

NASA Astrophysics Data System (ADS)

This catalog contains coordinates and both optical and infrared photometry, plus usefull tags, of the Blue Stars With Disk (BWE stars) discussed in detail in Guarcello et al. (2010, in prep): "Pre-main sequence stars with disks in the Eagle nebula observed in scattered light". The optical photometry in BVI bands comes from observations with WFI@ESO (Guarcello et al. 2007, Cat. J/A+A/462/245); JHK photometry have been obtained from 2MASS/PSC and UKIDSS/GPS catalogs (Bonatto et al., 2006A&A...445..567B, Guarcello et al., 2007, Cat. J/A+A/462/245 and 2010, in prep); IRAC data are from GLIMPSE public survey (Indebetouw 2007ApJ...666..321I, Guarcello et al., 2009, Cat. J/A+A/496/453); X-ray data from observations with Chandra/ACIS-I (Linsky et al. 2007, Cat. J/ApJ/654/347, Guarcello et al., 2007, Cat. J/A+A/462/245, Guarcello et al., 2010, in prep). BWE stars have been studied by analizing their Spectral Energy Distribution (SED) using the grid of YSO models developed by Robitaille et al. 2006ApJS..167..256R. (1 data file).

Guarcello, M. G.; Damiani, F.; Micela, G.; Peres, G.; Prisinzano, L.; Sciortino, S.

2010-06-01

258

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

NASA Astrophysics Data System (ADS)

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.

Strassmeier, K. G.

259

Improved Asteroid Astrometry and Photometry with Trail Fitting  

NASA Astrophysics Data System (ADS)

Asteroid detections in astronomical images may appear as trails due to a combination of their apparent rate of motion and exposure duration. Nearby asteroids in particular typically have high apparent rates of motion and acceleration. Their recovery, especially on their discovery apparition, depends upon obtaining good astrometry from the trailed detections. We present an analytic function describing a trailed detection under the assumption of a Gaussian point spread function (PSF) and constant rate of motion. We have fit the function to both synthetic and real trailed asteroid detections from the Pan-STARRS1 survey telescope to obtain accurate astrometry and photometry. For short trails our trailing function yields the same astrometric and photometry accuracy as a functionally simpler two-dimensional Gaussian but the latter underestimates the length of the trail - a parameter that can be important for measuring the object's rate of motion and assessing its cometary activity. For trails longer than about 10 pixels (˜3× PSF) our trail fitting provides ˜3× better astrometric accuracy and up to two magnitudes improvement in the photometry. The trail fitting algorithm can be implemented at the source detection level for all detections to provide trail length and position angle that can be used to reduce the false tracklet rate.

Vereš, Peter; Jedicke, Robert; Denneau, Larry; Wainscoat, Richard; Holman, Matthew J.; Lin, Hsing-Wen

2012-11-01

260

Model uncertainties affecting satellite-based inverse modeling of nitrogen oxides emissions and implications for surface ozone simulation  

NASA Astrophysics Data System (ADS)

Errors in chemical transport models (CTMs) interpreting the relation between space-retrieved tropospheric column densities of nitrogen dioxide (NO2) and emissions of nitrogen oxides (NOx) have important consequences on the inverse modeling. They are however difficult to quantify due to lack of adequate in situ measurements, particularly over China and other developing countries. This study proposes an alternate approach for model evaluation over East China, by analyzing the sensitivity of modeled NO2 columns to errors in meteorological and chemical parameters/processes important to the nitrogen abundance. As a demonstration, it evaluates the nested version of GEOS-Chem driven by the GEOS-5 meteorology and the INTEX-B anthropogenic emissions and used with retrievals from the Ozone Monitoring Instrument (OMI) to constrain emissions of NOx. The CTM has been used extensively for such applications. Errors are examined for a comprehensive set of meteorological and chemical parameters using measurements and/or uncertainty analysis based on current knowledge. Results are exploited then for sensitivity simulations perturbing the respective parameters, as the basis of the following post-model linearized and localized first-order modification. It is found that the model meteorology likely contains errors of various magnitudes in cloud optical depth, air temperature, water vapor, boundary layer height and many other parameters. Model errors also exist in gaseous and heterogeneous reactions, aerosol optical properties and emissions of non-nitrogen species affecting the nitrogen chemistry. Modifications accounting for quantified errors in 10 selected parameters increase the NO2 columns in most areas with an average positive impact of 22% in July and 10% in January. This suggests a possible systematic model bias such that the top-down emissions will be overestimated by the same magnitudes if the model is used for emission inversion without corrections. The modifications however cannot account for the large model underestimates in cities and other extremely polluted areas (particularly in the north) as compared to satellite retrievals, likely pointing to underestimates of the a priori emission inventory in these places with important implications for understanding of atmospheric chemistry and air quality. Post-model modifications also have large impacts on surface ozone concentrations with the peak values in July over North China decreasing by about 15 ppb. Individually, modification for the uptake of the hydroperoxyl radical on aerosols has the largest impact for both NO2 and ozone, followed by various other parameters important for some species in some seasons. Note that these modifications are simplified and should be used with caution for error apportionment.

Lin, J.-T.; Liu, Z.; Zhang, Q.; Liu, H.; Mao, J.; Zhuang, G.

2012-06-01

261

High-Quality Broadband BVRI Photometry of Benchmark Open Clusters  

NASA Astrophysics Data System (ADS)

Photometric techniques are often used to observe stars and it can be demonstrated that fundamental stellar properties can be observationally determined using calibrated sets of photometric data. Many of the most powerful techniques utilized to calibrate stellar photometry employ the use of stars in clusters since the individual stars are believed to have many common properties such as age, composition, and approximate distance. Broadband photometric Johnson/Cousins BVRI observations are presented for several nearby open clusters. The new photometry has been tested for consistency relative to archival work and shown to be both accurate and precise. The careful use of a regular routine when making photometric observations, along with the monitoring of instrumental systems and the use of various quality control techniques when making observations or performing data reductions, will enhance an observer's ability to produce high-quality photometric measurements. This work contains a condensed review of the history of photometry, along with a brief description of several popular photometric systems that are often utilized in the field of stellar astrophysics. Publications written by Taylor or produced during the early Taylor and Joner collaboration are deemed especially relevant to the current work. A synopsis of seven archival publications is offered, along with a review of notable reports of VRI photometric observations for the nearby Hyades open star cluster. The body of this present work consists of four publications that appeared between the years 2005 and 2008, along with a soon to be submitted manuscript for a fifth publication. Each of these papers deals specifically with high-quality broadband photometry of open clusters with new data being presented for the Hyades, Coma, NGC 752, Praesepe, and M67. It is concluded that the VRI photometry produced during the Taylor and Joner collaborative investigations forms a high-quality data set that has been: (1) stable for a period of more than 25 years; (2) monitored and tested several times for consistency relative to the broadband Cousins system, and (3) shown to have well-understood transformations to other versions of broadband photometric systems. Further work is suggested for: (1) the transformation relationships for the reddest stars available for use as standards; (2) the standardization of more fields for use with CCD detectors; (3) a further investigation of transformations of blue color indices for observations done using CCD detectors with enhanced UV sensitivity, and (4) a continuation of work on methods to produce high-quality observations of assorted star clusters (both open and globular) with CCD-based instrumentation and intermediate-band photometric systems.

Joner, Michael D.

262

Computational starspot photometry of contact binary stars  

NASA Astrophysics Data System (ADS)

Starspots are not well understood for contact binary star systems. The following properties of spots were systematically investigated: temperature, radius, colatitude, and longitude. Spots were modeled on an AE Phe like contact binary system. The spots were changed in a systematic manner. The light curve phases of primary minimum and primary maximum were affected by these parameter changes in a systematic manner, as well as the secondary minimum and maximum. It will be shown that it is possible to use the shift in these phases to study starspots over time. This information can also be used to identify the presence of spots in binary star systems. Starspots on contact binary systems are not commonly found at a longitude near 180°. The results of this study show that starspots near 180 ° should be the easiest to detect using photometric techniques. This is the most significant result from this study. Either there is an unknown physical reason why contact binary stars do not have starspots near a longitude of 180°, or the stars pots are there and the photometric data has been misinterpreted.

Hill, Robert

2007-08-01

263

Photometry of TNOs and Centaurs in support of a Herschel Key Programme  

NASA Astrophysics Data System (ADS)

Trans-Neptunian Objects (TNOs) and Centaurs represent the remnants of the leftover planetesimals from the early accretional phases of the outer preplanetary disk, hence the study of their physical properties is fundamental to constrain the formation and evolution of the outer Solar System. In particular, the measure of TNOs' albedos and sizes requires combined visible and thermal observations. In support of the "TNOs are Cool" programme, currently ongoing at the Herschel space telescope, we performed at the TNG telescope visible photometry of 23 TNOs and Centaurs. We derive the absolute magnitude HV of the targets, a fundamental information to interpret the Herschel data. Moreover, the B-V, V-R, V-I colors give us a first indication about the targets' surface composition. Finally, we combine our results with the available literature, looking for correlations between colors and dynamical properties of TNOs and Centaurs.

Perna, D.; Dotto, E.; Barucci, M. A.; Mazzotta Epifani, E.; Dall'Ora, M.; Vilenius, E.

2011-10-01

264

Galileo photometry of Apollo landing sites  

NASA Astrophysics Data System (ADS)

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).

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

1993-03-01

265

Retention and rainfastness of mancozeb as affected by physicochemical characteristics of adaxial apple leaf surface after enhanced UV-B radiation.  

PubMed

It is not clear so far whether alteration of leaf micromorphology and surface wax chemistry due to the impact of environmental factors, such as UV-B radiation, affects retention and rainfastness of applied pesticide solutions. In this study; UV-B treated and untreated adaxial leaf surfaces of apple seedlings (Malus domestica Borkh.) were characterized in terms of chemical composition, micromorphological fine structure, hydrophobicity, and wettability. Furthermore, the retention and rainfastness of applied fungicide mancozeb were studied. The samples were examined 0, 24 and 48 h after ultraviolet (UV)-B radiation (0.022 kW m(-2) for 150 min) The total wax mass, recovered from the adaxial leaf surface, amounted from 0.38 microg cm(-2) (control) up to 0.49 microg cm(-2) (24 h). Chemical composition of surface wax altered, whereas the contact angle of applied water droplets on leaf surface of UV-B treated plants did not change significantly compared to the control. The alteration of surface wax quantity and quality significantly affected retention of a.i.; it increased at a sampling time of 24 h after UV-B irradiation, whereas rainfastness of the fungicide spray solution was not significantly influenced. PMID:17365327

Bringe, Katja; Hunsche, Mauricio; Schmitz-Eiberger, Michaela; Noga, Georg

2007-02-01

266

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

Microsoft Academic Search

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

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

1998-01-01

267

Cell surface sialic acids do not affect primary CD22 interactions with CD45 and surface IgM nor the rate of constitutive CD22 endocytosis  

Microsoft Academic Search

CD22\\/Siglec-2 is a B cell-specific molecule modulating sur- face IgM (sIgM) signaling via cytosolic tyrosine-based motifs. CD22 recognizes a2-6-linked sialic acids (Sias) via an amino-terminal Ig-like domain. This Sia-binding site is typically masked by unknown sialylated ligands on the same cell surface, an interaction required for optimal signaling function. We studied the effect of cell surface Sias on specific interactions

Mai Zhang; Ajit Varki

2004-01-01

268

Acidic Deposition: State of Science and Technology. Report 10. Watershed and Lake Processes Affecting Surface Water Acid-Base Chemistry.  

National Technical Information Service (NTIS)

The acid-base chemistry of surface waters is governed by the amount and chemistry of deposition and by the biogeochemical reactions that generate acidity or acid neutralizing capacity (ANC) along the hydrologic pathways that water follows through watershe...

D. W. Johnson H. V. Miegroet J. W. Elwood R. B. Cook R. S. Turner

1990-01-01

269

An analysis of soil and surface properties which affect infiltration and runoff on mined lands, Centre County, Pennsylvania  

Microsoft Academic Search

Seventy-eight dripping rainfall simulator tests were performed on one- to four-year-old topsoiled areas of five surface coal mines. The data set consists of soil\\/surface properties and runoff volumes fit to the Horton infiltration equation. Systematic changes in infiltration through time necessitate an analysis of these variables grouped by age. In general, r-values increase when correlation matrices are divided by age.

D. W. Jorgensen; T. W. Gardner

1985-01-01

270

Auroral images from space - Imagery, spectroscopy, and photometry  

NASA Astrophysics Data System (ADS)

The design of the Auroral Ionospheric Remote Sensor (AIRS), a multimodal instrument comprising imagery, spectroscopy, and photometry subsystems, is described, with attention given to its electrooptics, mechanics, and electronics. The AIRS is a four-channel system that operates simultaneously in the vacuum UV (VUV), near-UV, and visible spectral bands. The sensor produces auroral images in both dark and sunlit hemispheres and enables the remote sensing of ionospheric airglows. The results of AIRS VUV spectrometer detectors sensitivity measurements for the two VUV channels are presented together with the AIRS optical schematic and the block diagram of its electrical system.

Schenkel, Frederick W.; Ogorzalek, Bernard S.

1987-09-01

271

BVI photometry of 5 CVn cloud galaxies (Karachentsev+ 1998)  

NASA Astrophysics Data System (ADS)

We present results of CCD imaging in B, V of five late-type galaxies with radial velocities V0<350km/s in the Canes Venatici cloud. Based on the photometry of their brightest blue stars we derived the following distances to the galaxies: 9.7Mpc for NGC 4144, 4.5Mpc for NGC 4244, 4.2Mpc for NGC 4395, 2.9Mpc for NGC 4449, and 8.2Mpc for UGC 8331. (1 data file).

Karachentsev, I. D.; Drozdovsky, I. O.

1998-01-01

272

Early Photometry of the Type IIP supernova SN 2013ej  

NASA Astrophysics Data System (ADS)

We report an early photometric observation of the Type IIP supernova SN 2013ej taken 15 hours before the official discovery (CBET #3606). We observed the field of M74 on 2013 July 24.80 - 24.83 UT using the 1m telescope at the Lulin Observatory in Taiwan. The supernova 2013ej was clearly detected in our multi-color observations. By comparing with the USNO and GSC2.3 catalogs, we derived the following optical (B, V, and R) photometry: B=13.8, V=14.0, and R=14.3.

Lee, M.; Li, K. L.; Wang, J.-W.; Kong, A. K. H.; Liu, H. B.; Huang, H.-J.; Huang, Y.-H.; Lin, Y.-M.; Yang, K.-C.; Program, on behalf of the Taipei First Girls'High School High Scope

2013-10-01

273

Analysis of RGU Photometry in Selected Area 51  

Microsoft Academic Search

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

S. Bilir; S. Karaali; R. Buser

2004-01-01

274

An algorithm for precise aperture photometry of critically sampled images  

NASA Astrophysics Data System (ADS)

We present an algorithm for performing precise aperture photometry on critically sampled astrophysical images. The method is intended to overcome the small-aperture limitations imposed by point sampling. Aperture fluxes are numerically integrated over the desired aperture, with sinc interpolation used to reconstruct values between pixel centres. Direct integration over the aperture is computationally intensive, but the integrals in question are shown to be convolution integrals and can be computed ? 10 000 times faster as products in the wavenumber domain. The method works equally well for annular and elliptical apertures and could be adapted for any geometry. A sample of code is provided to demonstrate the method.

Bickerton, S. J.; Lupton, R. H.

2013-05-01

275

Optical photometry and spectroscopy of Nova Del 2013  

NASA Astrophysics Data System (ADS)

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.

Tomov, T.; Ilkiewicz, K.; Swierczynski, E.; Belcheva, M.; Dimitrov, D.

2013-08-01

276

Under the surface: the dynamic interpersonal and affective world of psychopathic high-security and detention prisoners.  

PubMed

The present study yields an in-depth examination of the interpersonal and affective world of high-security and detention prisoners with possible (Psychopathy Checklist: Screening Version [PCL:SV] ? 13) and strong (PCL:SV ? 18) indications of psychopathy. A group of male inmates (n = 16) was compared with noncriminal and non-personality disordered controls (n = 35) on measures of self and other (Young Schema Questionnaire-Short Form [YSQ-SF], Inventory of Interpersonal Problems-Circumplex Scales [IIP-C]), and the experience and regulation of affect (Positive and Negative Affect Schedule [PANAS], Emotion Control Questionnaire 2 [ECQ2]). Results confirm the established grandiose, dominant, and callous characteristics of the psychopath (PCL:SV, Structured Clinical Interview for DSM-IV Axis II Disorders [SCID-II], DSM-IV and ICD-10 Personality Questionnaire [DIP-Q], IIP-C), while demonstrating personal distress and important nuances and variations in psychopathic offenders' interpersonal and affective functioning (YSQ-SF, PANAS, ECQ2, SCID-II, DIP-Q). These preliminary findings support, expand, and challenge the ordinary portrayal of the psychopath and, if replicated in larger samples, point to a need for an expansion or reformulation of the concept, measurement, and treatment of psychopathy. PMID:21791461

Gullhaugen, Aina Sundt; Nøttestad, Jim Aage

2011-07-26

277

Mutations in human papillomavirus type 16 L1 hypervariable surface-exposed loops affect L2 binding and DNA encapsidation.  

PubMed

Prophylactic vaccines against human papillomavirus (HPV) based on virus-like particles (VLP) induce type-specific neutralizing antibodies against a small number of hypervariable residues positioned in surface-exposed loops of the major capsid protein L1. To investigate the importance of these residues for neutralization, cross-neutralization, L2 incorporation and genome encapsidation, ten surface-exposed amino acid residues in four hypervariable loops of L1 were mutated. VLPs containing mutated or WT L1, with or without WT L2, were produced in 293TT cells using pseudovirion expression vectors. The mutations reduced the ability to induce neutralizing antibodies and to incorporate the L2 protein in the capsid. Ability to induce cross-neutralizing antibodies and to encapsidate pseudogenomes were completely abrogated. In summary, the surface-exposed L1 loops are important for the function of the HPV particle. PMID:23658208

Faust, Helena; Dillner, Joakim

2013-05-08

278

Bayesian inference of stellar parameters and interstellar extinction using parallaxes and multiband photometry  

NASA Astrophysics Data System (ADS)

Astrometric surveys provide the opportunity to measure the absolute magnitudes of large numbers of stars, but only if the individual line-of-sight extinctions are known. Unfortunately, extinction is highly degenerate with stellar effective temperature when estimated from broad-band optical/infrared photometry. To address this problem, I introduce a Bayesian method for estimating the intrinsic parameters of a star and its line-of-sight extinction. It uses both photometry and parallaxes in a self-consistent manner in order to provide a non-parametric posterior probability distribution over the parameters. The method makes explicit use of domain knowledge by employing the Hertzsprung-Russell Diagram (HRD) to constrain solutions and to ensure that they respect stellar physics. I first demonstrate this method by using it to estimate effective temperature and extinction from BVJHK data for a set of artificially reddened Hipparcos stars, for which accurate effective temperatures have been estimated from high-resolution spectroscopy. Using just the four colours, we see the expected strong degeneracy (positive correlation) between the temperature and extinction. Introducing the parallax, apparent magnitude and the HRD reduces this degeneracy and improves both the precision (reduces the error bars) and the accuracy of the parameter estimates, the latter by about 35 per cent. The resulting accuracy is about 200 K in temperature and 0.2 mag in extinction. I then apply the method to estimate these parameters and absolute magnitudes for some 47 000 F, G, K Hipparcos stars which have been cross-matched with Two-Micron All-Sky Survey (2MASS). The method can easily be extended to incorporate the estimation of other parameters, in particular metallicity and surface gravity, making it particularly suitable for the analysis of the 109 stars from Gaia.

Bailer-Jones, C. A. L.

2011-02-01

279

Rhomboid 4 (ROM4) Affects the Processing of Surface Adhesins and Facilitates Host Cell Invasion by Toxoplasma gondii  

PubMed Central

Host cell attachment by Toxoplasma gondii is dependent on polarized secretion of apical adhesins released from the micronemes. Subsequent translocation of these adhesive complexes by an actin-myosin motor powers motility and host cell invasion. Invasion and motility are also accompanied by shedding of surface adhesins by intramembrane proteolysis. Several previous studies have implicated rhomboid proteases in this step; however, their precise roles in vivo have not been elucidated. Using a conditional knockout strategy, we demonstrate that TgROM4 participates in processing of surface adhesins including MIC2, AMA1, and MIC3. Suppression of TgROM4 led to decreased release of the adhesin MIC2 into the supernatant and concomitantly increased the surface expression of this and a subset of other adhesins. Suppression of TgROM4 resulted in disruption of normal gliding, with the majority of parasites twirling on their posterior ends. Parasites lacking TgROM4 bound better to host cells, but lost the ability to apically orient and consequently most failed to generate a moving junction; hence, invasion was severely impaired. Our findings indicate that TgROM4 is involved in shedding of micronemal proteins from the cell surface. Down regulation of TgROM4 disrupts the normal apical-posterior gradient of adhesins that is important for efficient cell motility and invasion of host cells by T. gondii.

Buguliskis, Jeffrey S.; Brossier, Fabien; Shuman, Joel; Sibley, L. David

2010-01-01

280

Investigating the parameters affecting the adsorption of amino acids onto AgCl nanoparticles with different surface charges.  

PubMed

In this paper, adsorption behaviors of typical neutral (alanine), acidic (glutamic acid) and basic (lysine) amino acids onto the surfaces of neutral as well as positively and negatively charged silver chloride nanoparticles were examined. Silver chloride nanoparticles with different charges and different water content were synthesized by reverse micelle method. The adsorptions of the above mentioned amino acids onto the surfaces of differently charged silver chloride nanoparticles were found to depend strongly on various parameters including pH of the aqueous solution, type of amino acid, water to surfactant mole ratio, and type of charges on the surfaces of silver chloride nanoparticles. It was found that the interaction of -NH(3) (+) groups of the amino acids with silver ion could be a driving force for adsorption of amino acids. Alanine and Glutamic acid showed almost similar trend for being adsorbed on the surface of silver chloride nanoparticles. Electrostatic interaction, hydrophobicity of both nanoparticle and amino acid, complex formation between amine group and silver ion, interaction between protonated amine and silver ion as well as the number of nanoparticles per unit volume of solution were considered for interpreting the observed results. PMID:22491826

Absalan, Ghodratollah; Ghaemi, Maryam

2012-04-11

281

The Chrysalis Opens? Photometry from the eta Carinae Hubble Space Telescope Treasury Project, 2002-2006  

Microsoft Academic Search

During the past decade eta Car has brightened markedly, possibly indicating a change of state. Here we summarize photometry gathered by the Hubble Space Telescope (HST) as part of the HST Treasury Project on this object. Our data include Space Telescope Imaging Spectrograph (STIS) CCD acquisition images, Advanced Camera for Surveys HRC images in four filters, and synthetic photometry in

J. C. Martin; Kris Davidson; M. D. Koppelman

2006-01-01

282

The AAVSO Photoelectric Photometry Program in its Scientific and Socio-Historic Context  

Microsoft Academic Search

Photoelectric photometry began in the 1900s through the work of Guthnick, Stebbins, and others who constructed and used photometers based on the recently-discovered photoelectric effect. The mid 20th century saw a confluence of several areas of amateur interest: astronomy, telescope making, radio and electronics, and general interest in space. This is the time when AAVSO photoelectric photometry (PEP) began, with

John R. Percy

2011-01-01

283

ESO large program on physical studies of Transneptunian Objects and Centaurs: Visible photometry - First results  

Microsoft Academic Search

We present the first results of BVRI photometry of Transneptunian Objects (TNOs) and Centaurs obtained through the ESO Large Program on physical studies of these icy bodies in the outer solar system. In total 28 objects were observed of which 18 are new measurements. Combining our new BVRI photometry with the data summary published by Hainaut & Delsanti (\\\\cite{Hainaut2002}) results

H. Boehnhardt; A. Delsanti; A. Barucci; O. Hainaut; A. Doressoundiram; M. Lazzarin; L. Barrera; C. de Bergh; K. Birkle; E. Dotto; K. Meech; J. E. Ortiz; J. Romon; T. Sekiguchi; N. Thomas; G. P. Tozzi; J. Watanabe; R. M. West

2002-01-01

284

High-Speed CCD Photometry of White Dwarfs with a Small Telescope  

NASA Astrophysics Data System (ADS)

Small telescopes face a mission crisis and lack of funding in this age of bigger and bigger telescopes. High speed photometry of white dwarfs and other variables is a field in which these telescopes can be vital participants. We present high speed photometry taken at Mt. Cuba Observatory in Wilmington, Delaware, in collaboration with the Whole Earth Telescope.

Provencal, J. L.; Shipman, H. L.

2003-12-01

285

Kinematics and photometry of red clump stars (Vasquez+, 2013)  

NASA Astrophysics Data System (ADS)

The Kinematics and photometry for spectroscopic targets are presented. For each star with proper motions determination, the coordinates in each single epoch is provided. The spectroscopic targets were selected based on the optical V, I photometry of a bulge field centered at (l, b) = (0, -6), obtained with the WFI camera at the 2.2m telescope at ESO La Silla, on April 15th, 1999 as part of the ESO imaging Survey ESO programme (EIS, ESO programme ID 163.O-0741(A)). The resulting CMD has been already presented in Zoccali et al. (2003A&A...399..931Z) and McWilliam & Zoccali (2010ApJ...724.1491M). Based on this CMD the red clump targets were selected among the bright (red dots) and faint red clump stars (blue dots) for spectroscopic follow-up with Magellan IMACS spectrograph at the Las Campanas Observatory on July 10th, 2010 (R~5000) and VLT FLAMES-GIRAFFE spectrograph within the ESO programme ID 385.B-0735(B) (R~6500). In order to derive space velocities for our targets, second epoch images of the same field were obtained on May 6th, 2010 with the same instrument and filters as in the first epoch (ESO program ID 085.D-0143(A)). (1 data file).

Vasquez, S.; Zoccali, M.; Hill, V.; Renzini, A.; Gonzalez, O. A.; Gardner, E.; Debattista, Victor P.; Robin, A. C.; Rejkuba, M.; Baffico, M.; Monelli, M.; Motta, V.

2013-06-01

286

BVR photometry of the resolved dwarf galaxy Ho IX  

NASA Astrophysics Data System (ADS)

We present BVR CCD photometry down to limiting magnitude B=23.5 mag for 232 starlike objects and 11 diffuse objects in a 5.4 arcmin × 5.4 arcmin field of Ho IX. The galaxy is a gas-rich irregular dwarf galaxy possibly very close to M 81, which makes it especially interesting in the context of the evolution of satellite galaxies and the accretion of dwarf galaxies. Investigations of Ho IX were hampered by relatively large contradictions in the magnitude scale between earlier studies. With our new photometry we resolved these discrepancies. The color magnitude diagram (CMD) of Ho IX is fairly typical of a star-forming dwarf irregular, consistent with earlier results. Distance estimates from our new CMD are consistent with Ho IX being very close to M 81 and therefore being a definite member of the M 81 group, apparently in very close physical proximity to M 81. This work is a part of a joint project between the Astronomical Institute of the Ruhr-University in Bochum and the Institute of Astronomy of the Bulgarian Academy of Sciences for the study of nearby dwarf galaxies.

Georgiev, T. B.; Bomans, D. J.

2004-08-01

287

A new look at photometry of the Moon  

USGS Publications Warehouse

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.

Goguen, J. D.; Stone, T. C.; Kieffer, H. H.; Buratti, B. J.

2010-01-01

288

Optical and NIR Photometry of Open Cluster NGC 7790  

NASA Astrophysics Data System (ADS)

We present BVRI CCD photometry and near-infrared K photometry of the intermediate-aged open cluster NGC 7790. The reddening, E(B-V)=0.54 +/- 0.05 and the distance modulus, (m-M)_o=12.45 +/- 0.10 for the cluster were determined by zero-age-main-sequence fitting and theoretical isochrone fitting using not only (V, B-V), (V, V-I), (V, V-R) but also (V, V-K) color-magnitude diagrams. The reddening corresponded approximately to the average value derived from previous studies, while the distance modulus was found to be almost midway between the CCD photometric results of Romeo et al. (1989) and those of Mateo & Madore (1988). We have used four colors to distinguish members from field stars. The expected colors were calculated using the derived distance modulus, and were then were compared with the observed colors (B-V), (V-I), (V-R), and (V-K). Thus, a color excess E(B-V) for each star was determined which could give the minimum difference between the calculated and observed colors. Single and binary members of the cluster were determined on the basis of the E(B-V) distribution of stars.

Lee, Jung-Deok; Lee, Sang-Gak

1999-10-01

289

Multicolor photometry of triple system b Per requested  

NASA Astrophysics Data System (ADS)

Dr. Bob Zavala (U.S. Naval Observatory, Flagstaff) has requested AAVSO assistance in obtaining multicolor photometry of the bright triple system b Per in order to prepare for and detect a possible eclipse of the AB components by the C component predicted for 2013 January 23. Multi-color photometric observations of 4.5V b Per are requested 2013 January 23 through February 04. Based on a revised period of 702.45 ± 0.05 days, the next time of minimum light is predicted for HJD = 2456321.35 ± 0.05 (UT 2013 January 28 20:24UT ± 1.5 hours). The eclipse may last for up to four days, so the coverage requested will provide both a baseline out-of-eclipse light curve and a multi-color eclipse light curve for analysis. Photometry is needed at the level of 0.02-0.03 magnitude or better, as the eclipse may be as deep as 0.1 magnitude. For PEP observers, V coverage, and B if possible, is requested. DSLR observers should use whatever band(s) are available to them. Finder charts may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and links.

Waagen, Elizabeth O.

2013-01-01

290

A Conceptual Model to Predict the Deflation Threshold Shear Velocity as Affected by Near-Surface Soil Water  

Microsoft Academic Search

et al., 1996). McKenna-Neuman and Nickling (1989) proposed a theoretical model, in which they solved the A crucial parameter in predicting wind erosion is the deflation capillary force model of Fisher (1926) for cone-shaped threshold shear velocity, which is highly dependent on near-surface sand particles, and simply related the threshold shear soil water. The empirical and theoretical models to predict

Wim M. Cornelis; Donald Gabriels; Roger Hartmann

2004-01-01

291

Cell Surface Fucosylation Does Not Affect Development of Colon Tumors in Mice with Germline Smad3 Mutation  

Microsoft Academic Search

Background\\/Aims: Neoplasia-related alterations in cell surface ?(1,2)fucosylated glycans have been reported in multiple tumors including colon, pancreas, endometrium, cervix, bladder, lung and choriocarcinoma. Spontaneous colorectal tumors from mice with a germline null mutation of transforming growth factor-? signaling gene Smad3 (Madh3) were tested for ?(1,2)fucosylated glycan expression. Methods:Ulex europaeus agglutinin-I (UEA-I) lectin staining, fucosyltransferase gene Northern blot analysis, and a

Steven E. Domino; David M. Karnak; Elizabeth A. Hurd

2007-01-01

292

Microscopy of wear affected surface produced during sliding of Nimonic 80A against Stellite 6 at 20 °C  

Microsoft Academic Search

The microstructures of a wear induced surface glazed layer formed during sliding wear of Nimonic 80A against Stellite 6 at 20°C using a speed of 0.314 ms?1 under a load of 7 N have been investigated using X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy in combination with electron energy loss spectroscopy (EELS) and energy dispersive X-ray (EDX)

H. L Du; P. K Datta; I Inman; R Geurts; C Kübel

2003-01-01

293

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

Microsoft Academic Search

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

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

2010-01-01

294

Conformation of surface-decorating dextran chains affects the pharmacokinetics and biodistribution of doxorubicin-loaded nanoparticles.  

PubMed

Recent reports showed that subtle modifications of nanoparticle surface properties induced dramatic changes of interactions with serum proteins. The present work was aimed to investigate the effect of the conformation of dextran chains decorating the surface of poly(alkylcyanoacrylate) (PACA) nanoparticles on the pharmacokinetic and biodistribution of a model drug associated with the nanoparticles. Doxorubicin was associated with PACA nanoparticles prepared by anionic emulsion polymerization (AEP) (Dox-AEP) and redox radical emulsion polymerization (RREP) (Dox-RREP). Nanoparticles and the free drug (f-Dox) were injected intravenously to rats to determine the pharmacokinetic and biodistribution of doxorubicin. Curves of the pharmacokinetics showed a rapid phase of distribution followed by a slower elimination phase. Pharmacokinetic parameters of the distribution phase determined for the Dox-RREP were significantly different from those of f-Dox and Dox-AEP, while no difference was observed in the elimination phase of the three formulations. Rats treated with Dox-RREP showed lower Dox concentrations in liver but higher concentrations in heart, lungs, and kidneys compared to those treated with the other formulations. Dox-RREP exhibited a new type of stealth behavior characterized by a short circulation time and a rapid distribution in highly vascularized organs bypassing the MPS. The difference in pharmacokinetic and biodistribution observed between the drugs formulated with the two types of nanoparticles was attributed to the difference in the conformation of the dextran chains stranded on the nanoparticle surface. PMID:22465096

Alhareth, Khairallah; Vauthier, Christine; Bourasset, Fanchon; Gueutin, Claire; Ponchel, Gilles; Moussa, Fathi

2012-03-21

295

SHIELD: FITGALAXY -- A Software Package for Automatic Aperture Photometry of Extended Sources  

NASA Astrophysics Data System (ADS)

Determining the parameters of extended sources, such as galaxies, is a common but time-consuming task. Finding a photometric aperture that encompasses the majority of the flux of a source and identifying and excluding contaminating objects is often done by hand - a lengthy and difficult to reproduce process. To make extracting information from large data sets both quick and repeatable, I have developed a program called FITGALAXY, written in IDL. This program uses minimal user input to automatically fit an aperture to, and perform aperture and surface photometry on, an extended source. FITGALAXY also automatically traces the outlines of surface brightness thresholds and creates surface brightness profiles, which can then be used to determine the radial properties of a source. Finally, the program performs automatic masking of contaminating sources. Masks and apertures can be applied to multiple images (regardless of the WCS solution or plate scale) in order to accurately measure the same source at different wavelengths. I present the fluxes, as measured by the program, of a selection of galaxies from the Local Volume Legacy Survey. I then compare these results with the fluxes given by Dale et al. (2009) in order to assess the accuracy of FITGALAXY.

Marshall, Melissa

2013-01-01

296

Extreme Ultraviolet Explorer Photometry of RS Canum Venaticorum Systems: Four Flaring Megaseconds  

NASA Astrophysics Data System (ADS)

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 (P_orb<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 >0.5P_orb 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 ~10^33 ergs and a slope of -0.6. Flare energy increases with flare duration as E~Deltat^1.42, confirming the long-duration nature of high-energy flares on RS CVn systems. The integrated flare luminosity depends on the quiescent luminosity as L_flare~L^1.05_quiescent. 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.

Osten, Rachel A.; Brown, Alexander

1999-04-01

297

Narrow-band X-ray photometry as a tool for studying galaxy and cluster mass distributions  

NASA Astrophysics Data System (ADS)

We explore the utility of narrow-band X-ray surface photometry as a tool for making fully Bayesian, hydrostatic mass measurements of clusters of galaxies, groups and early-type galaxies. We demonstrate that it is sufficient to measure the surface photometry with the Chandra X-ray Observatory in only three (rest frame) bands (0.5-0.9, 0.9-2.0 and 2.0-7.0 keV) in order to constrain the temperature, density and abundance of the hot interstellar medium (ISM). Adopting parametrized models for the mass distribution and radial entropy profile and assuming spherical symmetry, we show that the constraints on the mass and thermodynamic properties of the ISM that are obtained by fitting data from all three bands simultaneously are comparable to those obtained by fitting similar models to the temperature and density profiles derived from spatially resolved spectroscopy, as is typically done. We demonstrate that the constraints can be significantly tightened when exploiting a recently derived, empirical relationship between the gas fraction and the entropy profile at large scales, eliminating arbitrary extrapolations at large radii. This `Scaled Adiabatic Model' is well suited to modest signal-to-noise ratio data, and we show that accurate, precise measurements of the global system properties are inferred when employing it to fit data from even very shallow, snapshot X-ray observations. The well-defined asymptotic behaviour of the model also makes it ideally suited for use in Sunyaev-Zeldovich studies of galaxy clusters.

Humphrey, Philip J.; Buote, David A.

2013-10-01

298

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

NASA Astrophysics Data System (ADS)

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.

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

2008-12-01

299

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

PubMed

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

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

2010-07-23

300

Changes in angular size and speed affect the judged height of objects moving over a ground surface.  

PubMed

Kersten et al (1997, Perception 26 171-192) showed that the perceived path of an object moving over a ground surface can be manipulated by changing the path of a shadow. Using a scene similar to Kersten's "ball-in-a-box" scene, we investigated the effect of angular size and angular speed in determining the perceived height of a moving sphere when optical contact (the position at which the object contacted the ground in the image) indicated that the sphere was receding in depth. In four experiments we examined both the effects of changes in size and speed, and the effects of constant levels of size and speed. Increases in angular size or speed during a motion sequence resulted in judgments of increased height above the ground plane. The angular size at the end of the motion sequence was also important in determining judged height, with greater height judged with larger final sizes. PMID:23678615

Zhang, Junjun; Braunstein, Myron L; Andersen, George J

2013-01-01

301

Performance of loblolly, Virginia, and shortleaf pine on a reclaimed surface mine as affected by Pisolithus tinctorius ectomycorrhizae and fertilization  

SciTech Connect

The effects of an induced Pisolithus tinctorius infection and broadcast fertilization were studied on the survival and growth of loblolly (Pinus taeda), Virginia (Pinus virginiana), and shortleaf (Pinus echinata) pine outplanted on a reclaimed east Tennessee coal surface mine site. The study site had been previously regraded and hydroseeded with a mixture of ground cover species. After six years, the survival and growth of loblolly pine with P. tinctorius ectomycorrhizae were signficantly improved in comparison with control loblolly pine infected by other ectomycorrhizal symbionts. The response of the Virginia pine to the infection by P. tinctorius was negligible after five years. Fertilization at outplanting significantly reduced the survival of both loblolly and Virginia pine. Fertilization of the shortleaf pine at the start of the third growing season did not result in the drastic mortality exhibited by the loblolly pine, and to a lesser extent the Virginia pine, in response to fertilization at outplanting, but this treatment was still detrimental to the survival of the shortleaf pine after five years. There was a marginal improvement in the survival and growth of the shortleaf pine in response to the infection by P. tinctorius. The effect of fertilization on the growth of all three species was negligible, and the increase in mortality associated with this treatment appeared to be primarily the result of increased competition with the ground cover species. These results indicate that the magnitude of the response exhibited by pines on harsh sites to an ectomycorrhizal infection by P. tinctorius is species dependent. Also, broadcast fertilization is inefficient on surface-mined sites where a vegetative ground cover has been established. 11 refs., 3 tabs.

Walker, R.F.; West, D.C.; McLaughlin, S.B.; Amundsen, C.C.

1985-01-01

302

Optical and infrared photometry of TX Canum Venaticorum  

SciTech Connect

UBVRJHK photometry during 1979--1982 indicates significant variability in the TX CVn binary system, with the optical brightness diminishing and the object growing redder. In the U band the amplitude was roughly-equal0/sup m/.6, while in the near infrared the brightness declined by 0/sup m/.1, on the average. To within +- 1 subtype, in 1981 the radiation of the system comprised that of a normal K5 giant and a B9 main-sequence star. The rest of the time excess optical emission was present, probably coming from a hot spot. The K-band flux density of the K5 giant implies a distance for TX CVn of roughly-equal1.1 kpc.

Taranova, O.G.; Yudin, B.F.

1983-01-01

303

UVBY photometry of blue stragglers in NGC 7789  

NASA Astrophysics Data System (ADS)

uvby photometry of 28 blue stragglers in the open cluster NGC 7789 is presented and analyzed. A rediscussion of the fundamental cluster parameters is presented. Comparison of these results with those from the blue stragglers indicates that standard photometric calibrations do apply to the stragglers. It is found that the extended halo of blue stragglers around NGC 7789 is composed predominantly of field stars, and that the radial distribution of the stragglers is similar to that of the red giants, implying that the progenitors of both classes of stars have the same mass, i.e., single stars near the cluster turnoff. When combined with weak photometric evidence for a lower bound to the luminosity distribution of the stragglers in the C-M diagram, it is concluded that the best current model for these enigmatic stars is that of a single star which has mixed internally, as delineated in the work of Saio and Wheeler (1980). Possibilities for future research are outlined.

Twarog, B. A.; Tyson, N.

1985-07-01

304

Vilnius photometry of IC1805 stars (Straizys+, 2013)  

NASA Astrophysics Data System (ADS)

Table 1 contains the results of photometry of 242 stars down to V=18mag in the Vilnius seven-color system in the direction of a young open cluster IC 1805. Photometric data are used to classify stars in spectral and luminosity classes. The identification numbers, coordinates, V magnitudes and six color indices in the Vilnius system, photometric spectral types and membership estimates are given. VSA are numbers from Vasilevskis et al. (1965AJ.....70..806V), and MJD are numbers from Massey et al. (1995, Cat. J/ApJ/454/151). The coordinates are from the PPMXL catalog (Roeser et al., 2010AJ....139.2440R, Cat. I/317>. (1 data file).

Straizys, V.; Boyle, R. P.; Janusz, R.; Laugalys, V.; Kazlauskas, A.

2013-04-01

305

Three Years of Photometry of the Delta Cepheid T Vulpecula  

NASA Astrophysics Data System (ADS)

Three years of UBV photoelectric photometry are presented for the Delta Cepheid, T Vulpecula. The observations were made by the Phoenix-10 automatic photoelectric telescope at the Fairborn Observatory in southern Arizona. T Vul was observed on over 100 different nights during this three-year period. Determination of times of maxima is proceeding using the "master curve" technique suggested by David G. Turner (Saint Mary's University, Halifax). We are thankful for the assistance of Louis J. Boyd (Fairborn Observatory) for telescope operations, Michael A. Seeds (Franklin and Marshall College) for telescope management and initial automated data reduction, and Russell M. Genet (Orion Observatory) and James R. Mueller (California Polytechnic State University) for technical advice. We acknowledge financial support by the Orion Observatory (observation funds) and the Department of Mathematics, California Polytechnic State University (conference and travel funds).

Nguyen, H. T.; Kyaw, T. T.

2004-12-01

306

Metallicity estimates of Galactic cepheids based on Walraven photometry .  

NASA Astrophysics Data System (ADS)

We present new empirical and theoretical calibrations of two photometric metallicity indices based on Walraven photometry. The empirical calibration relies on a sample of 48 Cepheids for which iron abundances based on high resolution spectra are available in the literature. They cover a broad range in metal abundance (-0.5 le [Fe/H]le +0.5) and the intrinsic accuracy of the Metallicity Index Color (MIC) relations is better than 0.2 dex. The theoretical calibration relies on a homogeneous set of scaled-solar evolutionary tracks for intermediate-mass stars and on pulsation predictions concerning the topology of the instability strip. The metal content of the adopted evolutionary tracks ranges from Z=0.001 to Z=0.03 and the intrinsic accuracy of the MIC relations is better than 0.1 dex.

Pedicelli, S.; Lub, J.; Pel, J. W.; Lemasle, B.; Bono, G.; François, P.

307

The Fast-Photometry Facilities at La Silla  

NASA Astrophysics Data System (ADS)

We briefly present in this note the available programme (and its environment) to perform fast photometry at La Silla. This facility has become available on the mountain a lang time aga already but recent discussions with same Visiting Astronomers tend to show that potential users are not yet weil aware of it. Many programmes have already been carried out with this mode of observing, mainly in the infrared but also in the visible. Let us mention, for instance: - Occultations of stars by planets to discover and/or study rings as weil as to determinate the temperatures and variations of the atmospheres of the planets. (See for instance: Bauchet et al., The Messenger No. 26, Dec. 1981 and Haefner et al., The Messenger No. 42, Dec.1985)

Bouchet, P.; Gutierrez, F.

1986-09-01

308

Exoplanet Photometry and Spectroscopy with HII/L2  

NASA Astrophysics Data System (ADS)

With the recent discovery of extrasolar planets (exoplanets) around nearby stars by indirect methods, one of the next goals of the exoplanet study is to directly detect the giant exoplanets and to make photometry and spectroscopy. The next decade will be the time to move from discovery to characterization of exoplanet systems. This, however, requires all of high sensitivity, high spatial resolution, and high dynamic range observations at infrared wavelengths, which will be difficult to achieve from the ground. In this paper, we describe a coronagraphic camera and spectrometer for the HII/L2 mission for mid- and far-infrared astronomy and show the photometry and spectroscopy of exoplanets to be one of the most important scientific aims for this mission. The proposed HII/L2 coronagraph will cover the wavelength between 4 and 27 micron, optimized at 5 micron. The plate scale is about 0.06 arcsec, covering a field-of-view of about 1 arcmin by 1 arcmin with a 1024x1024 array detector. Occulting masks of diameter greater than 0.72 arcsec will be available, which enables the observations of exoplanets beyond ~2 AU around nearby (d~5 pc) stars. The coronagraph greatly takes advantage of the single (non-segmented) mirror of the HII/L2 telescope design. A high-efficiency Ge or CdTe grism with a resolution of a few hundreds will be installed for the coronagraphic spectroscopy of the exoplanet atmosphere. Rich spectral features at mid-infrared wavelengths enable us to study various atmospheric components and to make a comparative study of the exoplanets and our solar system planets.

Tamura, M.

2000-12-01

309

Four Decades of TiO/CN Classification Photometry  

NASA Astrophysics Data System (ADS)

Photometry on the writer's eight-color narrow-band system has entered its 40th year. This poster, in connection with the HAD Special Session on "Photometry: Past and Present," reviews the history of the system and its applications. Employing interference filters approximately 50 Å in width to measure the strongest bands of TiO, VO, and CN as well as continuum points in the 7000 -- 11000 Å spectral region, the system is used primarily to provide two-dimensional spectral classifications for M stars. A precision of 0.1 spectral subtype is routinely obtained for normal stars of type K4.0 or later. The first two sets of filters were manufactured in 1969, and the first observations were made with the Perkins 1.8-m telescope at Lowell Observatory. A decade later, after some of the original filters had deteriorated, new filter sets were made for several individuals and observatories including KPNO and CTIO. During the 1970s, observations were made with S-1 photomultipliers and the emphasis was on bright stars. Later, with the acquisition of the more sensitive Varian LSE photocells by both KPNO and CTIO, observations extended to red giant cluster members, K and M supergiants in the Magellanic Clouds, and faint suspected Galactic supergiants. Observations were briefly interrupted when the ASCAP photometer at CTIO was taken out of service in 2001, but were resumed in 2003 with the establishment of the SMARTS consortium. Large-format filters representing the first 6 filters of the 8-color system have been acquired to allow work by CCD imaging. At least 15 observers have contributed an estimated 16,000 sets of narrow-band data for approximately 5000 different stars to date.

Wing, Robert F.

2009-01-01

310

DIVA, the Next Global Astrometry and Photometry Mission  

NASA Astrophysics Data System (ADS)

The small German satellite DIVA is intended to provide highest-quality astrometric and multi-band spectrophotometric data for a complete sky survey of about 35 million stars. The satellite is planned to operate for two years, starting early 2004. Final results will be generally available in 2008. With about 300 times as many stars as Hipparcos, typically five times the astrometric precision, and the provision of multi-colour photometry in several dozen optical and near-UV bands, DIVA will be the next milestone in the series of global astrometric data sets that started with the Hipparcos Catalogue in 1997 and which will culminate in the GAIA data products around 2018. The talk will present a brief description of the project and its planned products. DIVA's scientific potential for galactic astronomy and stellar astrophysics will be outlined by examples from different fields of research. DIVA's applications will generally cover similar areas as those of Hipparcos, but at a greatly increased scale. While Hipparcos provided about 20,000 parallaxes of 10 percent relative precision (out to about 100 pc), DIVA will yield about 250,000 of them, out to about 600 pc. Proper motions will have precisions up to 0.1 milli-arcsec/year, corresponding to a tangential velocity of 1 km/s at a distance of 2 kpc. The multi-colour photometry will give a fairly clear physical characterization of a large proportion of the observed stars, largely eliminating the need of extensive ground-based parallel observation campaigns for the selection of specific stellar samples within the DIVA data.

Röser, S.; Bastian, U.

311

Recovering physical properties from narrow-band photometry  

NASA Astrophysics Data System (ADS)

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.

Schoenell, W.; Cid Fernandes, R.; Benítez, N.; Vale Asari, N.

2013-05-01

312

Near-nucleus Photometry of Outbursting Comet 17P/Holmes  

NASA Astrophysics Data System (ADS)

Comet 17P/Holmes underwent the largest cometary outburst in recorded history on UT 2007 October 23, releasing massive quantities of dust and gas. We used the Canada-France-Hawaii Telescope to obtain wide-field images of 17P/Holmes on 15 dates over a period of three months following the outburst and employ them here to examine the subsequent activity of the nucleus and the nature of the ejecta closest to the nucleus. Through aperture photometry we observed the inner coma (within 2500 km of the nucleus) to fade from an apparent magnitude of 11.7 mag to 17.6 mag, corresponding to absolute magnitudes of 8.1 mag and 12.4 mag, between UT 2007 November 6 and 2008 February 12. A second much smaller outburst occurred on UT 2007 November 12, three weeks after the original outburst, suggesting that the nucleus remained unstable. The surface brightness profile of the inner coma was consistently shallow relative to the expected steady-state profile, and showed a persistent brightness enhancement within ~5000 km of the nucleus. We propose that sublimating ice grains created an ice grain halo around the nucleus, while fragmenting grains were responsible for the shallow surface brightness profile.

Stevenson, Rachel; Jewitt, David

2012-11-01

313

The AAVSO Photoelectric Photometry Program in Its Scientific and Socio-Historic Context  

NASA Astrophysics Data System (ADS)

In this paper, I review the work of the AAVSO in the area of photoelectric photometry (PEP). This work was influenced by several trends: in science, in technology, and in the sociology of amateur astronomy. Through the 1980s, the AAVSO photoelectric photometry program competed with other such programs and, in recent years, has been overshadowed by CCD photometry programs. Nevertheless, the AAVSO PEP program has, through careful organization, motivation, and feedback, produced extensive scientific results, and can continue to do so. In the case of my own research, AAVSO PEP observations have also contributed significantly to the education of my students.

Percy, J. R.

2012-06-01

314

STRÖMGREN Photometry of the Supergiants HD 4841 (B5 Ia) and HD 194279 (B2 Ia)  

NASA Astrophysics Data System (ADS)

We investigated the variability of the B Ia supergiants HD 4841 and HD 194279 using Strömgren photometry obtained with the Four College Automated Photoelectric Telescope, Arizona and the 0.4-m telescope of TÜB?TAK National Observatory (TUG), Turkey. Both stars are definitely variable with amplitudes of order 0.10 mag in u, v, b and y. The Turkish photometry with several observations per night suggests a more rapid variability than the once per night American photometry. The periods of variability are likely to be of the order of one day.

Adelman, Saul J.; Yüce, Kutluay

315

Snow cover and ground surface temperature on a talus slope affected by mass movements. Veleta cirque, Sierra Nevada, Spain  

NASA Astrophysics Data System (ADS)

This paper analyses the thermal ground behaviour on an alpine talus slope located at the foot of the north wall of the glacial cirque on the Pico del Veleta (3398 m, 37°03'21''N, 3°21'57''W, MAAT: -0,4°C) in Sierra Nevada, SE Spain. There are frequent mass movements on this talus slope, particularly in its central section, caused by the abundant presence of fine-grained sediment and by the water from snowmelt and/or ice degradation in the ground or permafrost (Gómez et al., 2003). To determine the snowmelt pattern and ocurrence of permafrost, a continuous ground surface temperature was kept by installing 6 mini-loggers (HOBO Pendant) along the descending profile of the central talus, which is 170 m long with altitudes ranging from 3180 m at the higher end to 3085 m at the lower end. A thermal borehole was also installed at a depth of 2 m at the base of the slope on an active rock glacier. The results obtained for the period October 2008 - September 2009 show that, in contrast to alpine talus slopes (Luetschg et. al., 2004; Lambiel and Pieracci, 2008), the upper part of the slope is characterized by mean annual ground surface temperatures (MAGST) lower than at the base of the talus, possibly due to the effect of the shadow of the cirque wall. The MAGST oscillate between 0.592°C at the station near the slope apex (S2) and 1.836°C at the station near the base (S5). In winter-spring, when the talus slope is covered with snow, the GST are stabilized at all stations between mid-October and early November. The minimum GST, which express the BTS conditions, oscillate between 0.232 and 0.01°C, depending on the month, with lowest values recorded during the month of April. Only one station (S3, mid-slope) recorded negative values (max. value : - 0.549°C in December and - 0.211 in April ). In summer, the snow disappears fairly quickly between mid- and late July on the intermediate stretch of the talus slope (S3, S4, S6), where the majority of the flows detected occur. In the mid-upper part (S5, S2) the thaw occurs in mid-August. The GST data provide evidence of the current absence of permafrost along the talus slope profile, although some years ago it was detected using BTS methods (Gómez et al., 2003. Gómez-Ortiz, A., Palacios, D., Luengo, E., Tanarro, L. M.; Schulte, L. and Ramos, M., 2003. Talus instability in a recent deglaciation area and its relationship to buried ice and snow cover evolution (Picacho del Veleta, Sierra Nevada, Spain). Geografisca Annaler 85 A (2), 165-182. Lambiel, C. and Pieracci, K. 2008. Permafrost distribution in talus slopes located within the alpine periglacial belt, Swiss Alps. Permafrost and Periglac. Process. 19: 293-304 Luetschg, M.; Stoeckli, M.; Lehning, M.; Haeberli, W., and Ammann, W. 2004. Temperatures in two boreholes at Flüela Pass, Eastern Swiss Alps: the effect of snow redistribution on permafrost distribution patterns in high mountain areas. Permafrost and Periglac. Process. 15: 283-297. Research funded by CGL2009-7343 project, Government of Spain.

Tanarro, L. M.; Palacios, D.; Gómez-Ortiz, A.; Salvador-Franch, F.

2012-04-01

316

Face shape of unaffected parents with cleft affected offspring: combining three-dimensional surface imaging and geometric morphometrics  

PubMed Central

Objective Various lines of evidence suggest that face shape may be a predisposing factor for nonsyndromic cleft lip with or without cleft palate (CL/P). In the present study, 3D surface imaging and statistical shape analysis were used to evaluate face shape differences between the unaffected (non-cleft) parents of individuals with CL/P and unrelated controls. Methods Sixteen facial landmarks were collected from 3D captures of 80 unaffected parents and 80 matched controls. Prior to analysis, each unaffected parent was assigned to a subgroup on the basis of prior family history (positive or negative). A geometric morphometric approach was utilized to scale and superimpose the landmark coordinate data (Procrustes analysis), test for omnibus group differences in face shape, and uncover specific modes of shape variation capable of discriminating unaffected parents from controls. Results Significant disparity in face shape was observed between unaffected parents and controls (p < 0.01). Notably, these changes were specific to parents with a positive family history of CL/P. Shape changes associated with CL/P predisposition included marked flattening of the facial profile (midface retrusion), reduced upper facial height, increased lower facial height and excess interorbital width. Additionally, a sex-specific pattern of parent-control difference was evident in the transverse dimensions of the nasolabial complex. Conclusions The faces of unaffected parents from multiplex cleft families display meaningful shape differences compared with the general population. Quantitative assessment of the facial phenotype in cleft families may enhance efforts to discover the root causes of CL/P.

Weinberg, SM; Naidoo, SD; Bardi, KM; Brandon, CA; Neiswanger, K; Resick, JM; Martin, RA; Marazita, ML

2009-01-01

317

Temperature-induced changes in the lipopolysaccharide of Yersinia pestis affect plasminogen activation by the pla surface protease.  

PubMed

The Pla surface protease of Yersinia pestis activates human plasminogen and is a central virulence factor in bubonic and pneumonic plague. Pla is a transmembrane beta-barrel protein and member of the omptin family of outer membrane proteases which require bound lipopolysaccharide (LPS) to be proteolytically active. Plasminogen activation and autoprocessing of Pla were dramatically higher in Y. pestis cells grown at 37 degrees C than in cells grown at 20 degrees C; the difference in enzymatic activity by far exceeded the increase in the cellular content of the Pla protein. Y. pestis modifies its LPS structure in response to growth temperature. We purified His(6)-Pla under denaturing conditions and compared various LPS types for their capacity to enhance plasmin formation by His(6)-Pla solubilized in detergent. Reactivation of His(6)-Pla was higher with Y. pestis LPSs isolated from bacteria grown at 37 degrees C than with LPSs from cells grown at 25 degrees C. Lack of O antigens and the presence of the outer core region as well as a lowered level of acylation in LPS were found to enhance the Pla-LPS interaction. Genetic substitution of arginine 138, which is part of a three-dimensional protein motif for binding to lipid A phosphates, decreased both the enzymatic activity of His(6)-Pla and the amount of Pla in Y. pestis cells, suggesting the importance of the Pla-lipid A phosphate interaction. The temperature-induced changes in LPS are known to help Y. pestis to avoid innate immune responses, and our results strongly suggest that they also potentiate Pla-mediated proteolysis. PMID:20368351

Suomalainen, Marjo; Lobo, Leandro Araujo; Brandenburg, Klaus; Lindner, Buko; Virkola, Ritva; Knirel, Yuriy A; Anisimov, Andrey P; Holst, Otto; Korhonen, Timo K

2010-04-05

318

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

SciTech Connect

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.

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

2007-02-07

319

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)

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.

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

2008-05-01

320

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

PubMed

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

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

2012-03-23

321

Galaxy Evolution in Ten Nearby Clusters Through XMM-OM Ultraviolet Photometry  

NASA Astrophysics Data System (ADS)

We report on a program capitalizing on the availability of XMM Optical Monitor(XMM-OM) ultraviolet (UV) photometry to study galaxy evolution in clusters. We have produced a sample of ten nearby Abell clusters with XMM-OM, SDSS, and GALEX photometry, including nearly 800 objects with SDSS spectra and XMM-OM UV photometry. Of these, over 500 are galaxies belonging to the parent cluster sample. We use this large database to explore color-magnitude relations and identify various classes of objects. We further demonstrate the application of XMM-OM UV photometry to evaluate the star formation histories of galaxies. Support for this work is provided by NASA Award Number NNX09AC76G.

Miller, Neal A.; Yen, S.

2011-01-01

322

Stellar Population Properties and Evolution Analysis of NGC 628 with Panchromatic Photometry  

NASA Astrophysics Data System (ADS)

Panchromatic spectral energy distribution from the ultraviolet, optical to infrared photometry of NGC 628, combined with evolutionary stellar population synthesis, is used to derive the spatially resolved age, metallicity, and reddening maps. These parameter distributions show that the bulge of this galaxy is a disk-like pseudobulge, which has a Sérsic index close to the exponential law, rich gas, and a young circumnuclear ring structure. We also discover that the disk has two distinct regions with different radial age and metallicity gradients. The inner region is older and has a much steeper age gradient than the outer region of the disk. Both these two regions and the central young structure can be seen in the radial profile of the optical color. Based on the age and reddening distributions, we conclude that the pseudobulge and disk are likely to have grown via secular evolution, which is the redistribution of mass and energy through the angular momentum transport caused by the non-axisymmetric potential of the spirals. However, possible gas accretion events could affect the outer region of the disk due to abundant H I gas accumulating in the outer disk.

Zou, Hu; Zhang, Wei; Yang, Yanbin; Zhou, Xu; Jiang, Zhaoji; Ma, Jun; Wu, Zhenyu; Wu, Jianghua; Zhang, Tianmeng; Fan, Zhou

2011-07-01

323

STELLAR POPULATION PROPERTIES AND EVOLUTION ANALYSIS OF NGC 628 WITH PANCHROMATIC PHOTOMETRY  

SciTech Connect

Panchromatic spectral energy distribution from the ultraviolet, optical to infrared photometry of NGC 628, combined with evolutionary stellar population synthesis, is used to derive the spatially resolved age, metallicity, and reddening maps. These parameter distributions show that the bulge of this galaxy is a disk-like pseudobulge, which has a Sersic index close to the exponential law, rich gas, and a young circumnuclear ring structure. We also discover that the disk has two distinct regions with different radial age and metallicity gradients. The inner region is older and has a much steeper age gradient than the outer region of the disk. Both these two regions and the central young structure can be seen in the radial profile of the optical color. Based on the age and reddening distributions, we conclude that the pseudobulge and disk are likely to have grown via secular evolution, which is the redistribution of mass and energy through the angular momentum transport caused by the non-axisymmetric potential of the spirals. However, possible gas accretion events could affect the outer region of the disk due to abundant H I gas accumulating in the outer disk.

Zou Hu; Zhang Wei; Yang Yanbin; Zhou Xu; Jiang Zhaoji; Ma Jun; Wu Zhenyu; Wu Jianghua; Zhang Tianmeng; Fan Zhou, E-mail: zhouxu@bao.ac.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2011-07-15

324

The RS CVn binary HK Lacertae: long-term photometry from Sonneberg sky-patrol plates  

Microsoft Academic Search

Long-term photographic photometry of the active long-period RS CVn binary HK Lac (HD 209813) was obtained from more than 2000 Sonneberg Sky-Patrol plates taken between 1956 and 1996. We achieve an internal accuracy of 0. m07. The correspondence with contemporaneous high-precision photoelectric photometry from automatic telescopes is striking and successfully demonstrates the feasibility of our approach. Based on a Bayesian

H.-E. Fröhlich; P. Kroll; K. G. Strassmeier

2006-01-01

325

TRIFFID Photometry of Globular Cluster Cores - I. Photometric Techniques and Variable Stars in M15  

Microsoft Academic Search

The Galway\\/DIAS Image Sharpening Camera, TRIFFID, has been used to make observations in two colours of the centre of the post-core-collapse globular cluster M15. We present here our analysis of the photometry in B over two seasons. We have combined the complementary qualities of the HST's high astrometric precision and TRIFFID's extended coverage and photometric precision, to perform crowded-field photometry

R. F. Butler; A. Shearer; R. M. Redfern; M. Colhoun; P. O'Kane; A. J. Penny; P. W. Morris; W. K. Griffiths; M. Cullum

1998-01-01

326

Time-series UV Photometry Of Two Variable Carbon-atmosphere (DQV) White Dwarfs  

NASA Astrophysics Data System (ADS)

We present time-series near-UV photometry of two variable carbon-atmosphere (DQV) white dwarfs observed with GALEX. We compare the amplitudes, periods, and phases of these data with contemporaneous ground-based optical time-series photometry. These results help to shed light on DQVs, their properties, and the source of the variability. This research is funded by NASA-GALEX grant NNX11AG82G.

Williams, Kurtis A.; Montgomery, M. H.; Winget, D. E.

2012-01-01

327

BVRIJHK photometry and proper motion analysis of NGC 6253 and the surrounding field  

Microsoft Academic Search

Context: We present a photometric and astrometric catalog of 187 963 stars located in the field around the old super-metal-rich Galactic open cluster NGC 6253. The total field-of-view covered by the catalog is 34''×33''. In this field, we provide CCD BVRI photometry. For a smaller region close to the cluster's center, we also provide near-infrared JHK photometry. Aims: We analyze

M. Montalto; G. Piotto; S. Desidera; I. Platais; G. Carraro; Y. Momany; F. de Marchi; A. Recio-Blanco

2009-01-01

328

Southern Milky Way carbon stars - New candidates, JHK photometry, and radial velocities  

SciTech Connect

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.

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

329

Vilnius Photometry of Red Giant Stars in the Open Cluster NGC 7789  

NASA Astrophysics Data System (ADS)

Photoelectric Vilnius seven-color photometry is presented and analyzed for a sample of 24 red giant branch and clump stars in the open cluster NGC 7789. For each star we have determined photometric spectral type, absolute magnitude, interstellar reddening, effective temperature, metallicity, and surface gravity. From averages over the stars in the sample we find the mean reddening to the cluster E Y-V = 0.21± 0.02 (s.d.), or E B-V = 0.25, and the apparent distance modulus (m-M) V = 12.21± 0.10 (s.d.), which yield a distance of 1840 pc. The mean overall metallicity is found to be [Fe/H] = -0.18± 0.09 (s.d.). The clump stars, on average, appear to be slightly more metal-rich than the other red giants, which is most probably caused by evolutionary changes of carbon and nitrogen molecular bands falling in the photometric passbands. A difference in mass between the two groups of stars has also been detected, which suggests that the clump stars might have undergone extra mass loss before reaching their core He-burning phase of evolution.

Bartašiut?, Stanislava; Tautvaišien?, Gražina

2004-12-01

330

SOAP: A Tool for the Fast Computation of Photometry and Radial Velocity Induced by Stellar Spots  

NASA Astrophysics Data System (ADS)

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.

Boisse, I.; Bonfils, X.; Santos, N. C.; Figueira, P.

2013-04-01

331

SYNMAG Photometry: A Fast Tool for Catalog-level Matched Colors of Extended Sources  

NASA Astrophysics Data System (ADS)

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.

Bundy, Kevin; Hogg, David W.; Higgs, Tim D.; Nichol, Robert C.; Yasuda, Naoki; Masters, Karen L.; Lang, Dustin; Wake, David A.

2012-12-01

332

SYNMAG PHOTOMETRY: A FAST TOOL FOR CATALOG-LEVEL MATCHED COLORS OF EXTENDED SOURCES  

SciTech Connect

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.

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

333

IRSF SIRIUS JHKs Simultaneous Transit Photometry of GJ 1214b  

NASA Astrophysics Data System (ADS)

We report on the high-precision transit photometry of GJ 1214b in JHKs bands simultaneously taken with the SIRIUS camera on the Infrared Survey Facility 1.4 m telescope located in Sutherland, South Africa. Our Markov-Chain Monte Carlo analysis shows that observed planet-to-star radius ratios in the JHKs bands are Rp/Rs,J = 0.11833 ± 0.00077, Rp/Rs,H = 0.11522 ± 0.00079, and Rp/Rs,Ks = 0.11459 ± 0.00099, respectively. The radius ratios are very consistent with previous studies by Bean et al. (2011, ApJ, 743, 92) within 1 ?, while our ratio in the Ks band is shallower than previous measurements in the same band by Croll et al. (2011, ApJ, 736, 78) and inconsistent even at the 4? level with them. We have no satisfactory explanation for this discrepancy at this point. Our overall results support a flat transmission spectrum in the observed bands, which can be explained by a water-dominated atmosphere or an atmosphere with extensive high-altitude clouds or haze. To explain the discrepancy of the radius ratios, and to determine a definitive atmosphere model for GJ 1214b in the future, more extended transit observations in around the Ks band would be especially important.

Narita, Norio; Nagayama, Takahiro; Suenaga, Takuya; Fukui, Akihiko; Ikoma, Masahiro; Nakajima, Yasushi; Nishiyama, Shogo; Tamura, Motohide

2013-04-01

334

HUBBLE SPACE TELESCOPE PHOTOMETRY OF GLOBULAR CLUSTERS IN M81  

SciTech Connect

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.

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

335

Multicolor photometry of the nearby galaxy cluster A119  

NASA Astrophysics Data System (ADS)

This paper presents multicolor optical photometry of the nearby galaxy cluster Abell 119 (z = 0.0442) with the Beijing-Arizona-Taiwan-Connecticut system of 15 intermediate bands. Within the BATC field of view of 58' × 58', there are 368 galaxies with known spectroscopic redshifts, including 238 member galaxies (called sample I). Based on the spectral energy distributions of 1376 galaxies brighter than iBATC = 19.5, the photometric redshift technique and the color-magnitude relation of early-type galaxies are applied to select faint member galaxies. As a result, 117 faint galaxies were selected as new member galaxies. Combined with sample I, an enlarged sample (called sample II) of 355 member galaxies is obtained. Spatial distribution and localized velocity structure for two samples demonstrate that A119 is a dynamically complex cluster with at least three prominent substructures in the central region within 1 Mpc. A large velocity dispersion for the central clump indicates a merging along the line of sight. No significant evidence for morphology or luminosity segregations is found in either sample. With the PEGASE evolutionary synthesis model, the environmental effect on the properties of star formation is confirmed. Faint galaxies in the low-density region tend to have longer time scales of star formation, smaller mean stellar ages, and lower metallicities in their interstellar medium, which is in agreement with the context of the hierarchical cosmological scenario.

Tian, Jin-Tao; Yuan, Qi-Rong; Zhou, Xu; Jiang, Zhao-Ji; Ma, Jun; Wu, Jiang-Hua; Wu, Zhen-Yu; Fan, Zhou; Zhang, Tian-Meng; Zou, Hu

2012-10-01

336

Transit Timing Variations as an Exercise for High Precision Photometry  

NASA Astrophysics Data System (ADS)

Extrasolar planet transit timing variations (TTVs) provide an excellent means of professional/amateur collaboration that can also serve as a good test-project to assess an effort to improve a research telescope's photometry performance. I started a global telescope TTV project to look for perturbations in the timing of transits of known extrasolar planets as a project to "work out” the newly acquired telescopes. These perturbations can indicate the presence of unknown additional planets that if under favorable resonance conditions can reveal planets with a mass as low as an earth mass. TTV observations also do double by how the light curves provides an opportunity to do detailed study of the planet and star's effects on the light curve. For these purposed I arranged a collaboration to use the FTN telescope on Maui, Hawaii, and we joined the larger Transit Light Curve (TLC) project. I was stationed near FTN in Maui, Hawaii to do a year-long effort to commission the 2.0m FTN, using such test projects. Results that are available a year after this project started will be presented. Professional/amateur collaborations are particularly essential to this project especially in the event that the original telescope data fails to be released. Expected accomplishments of achieving the full data will be presented.

Taylor, Stuart F.

2009-01-01

337

macula: Rotational modulations in the photometry of spotted stars  

NASA Astrophysics Data System (ADS)

Photometric rotational modulations due to starspots remain the most common and accessible way to study stellar activity. Modelling rotational modulations allows one to invert the observations into several basic parameters, such as the rotation period, spot coverage, stellar inclination and differential rotation rate. The most widely used analytic model for this inversion comes from Budding (1977) and Dorren (1987), who considered circular, grey starspots for a linearly limb darkened star. That model is extended to be more suitable in the analysis of high precision photometry such as that by Kepler. Macula, a Fortran 90 code, provides several improvements, such as non-linear limb darkening of the star and spot, a single-domain analytic function, partial derivatives for all input parameters, temporal partial derivatives, diluted light compensation, instrumental offset normalisations, differential rotation, starspot evolution and predictions of transit depth variations due to unocculted spots. The inclusion of non-linear limb darkening means macula has a maximum photometric error an order-of-magnitude less than that of Dorren (1987) for Sun-like stars observed in the Kepler-bandpass. The code executes three orders-of-magnitude faster than comparable numerical codes making it well-suited for inference problems.

Kipping, David, M.

2012-09-01

338

Stromgren $u$ Photometry of CH Cygni in 1995 and 1996  

NASA Astrophysics Data System (ADS)

Rapid time-resolution, Stromgren u-band photometry of CH cygni shows a marked decrease in quasi-periodic, short time scale ( ~ 2000--3000 s) variability between 1995 August and 1996 June. In 1995, we detected variability of ~ 0.3--0.4 mag with periods of ~2200 s and ~2700 s, which are remarkably similar to periods reported by Hoard (1993) from similar u-band measurements of CH Cyg in 1992. In contrast, during a number of nights in 1996 the u magnitude was roughly constant within 0.1 mag, and the light curves showed no evidence of rapid variability. The average u magnitude of CH Cyg decreased by ~ 0.9 mag between 1995 and 1996, suggesting a common source for the quasi-periodic variability and the u-band luminosity, namely the hot component in the interacting binary. We discuss several possible explanations for this variability, including the spin of an accreting, magnetic white dwarf (as in the intermediate polar class of cataclysmic variables) and the reprocessing of accretion-induced radiation from the white dwarf in circumstellar material. (SECTION: Stars)

Rodgers, B.; Hoard, D. W.; Burdullis, T.; Machado-Pelaez, L.; O'Toole, M.; Reed, S.

1997-10-01

339

Photometry, Spectroscopy, and Classification of Nova V475: Erratum  

NASA Astrophysics Data System (ADS)

In the paper "Photometry, Spectroscopy, and Classification of Nova V475 Scuti" by D. Starkey (JAAVSO, 2005, 34, 36-42), there is an error in Equation (2), the descriptions of Equations (2) and (3) should be amended, and a fourth equation and its description should be added. Equation (2) should read: "Mv = -7.92 ± 0.81 arctan {(1.32 - log(t2))/0.23} (2)" The description of Equation (2) should read: "where Mv equals the absolute V-band magnitude of the nova, t2 is the time in days for the nova to drop exactly two magnitudes in brightness in the V-band, and the value of the arctangent is in radians." The description for Equation (3) should read: "where mv equals the apparent or observed magnitude of V475 Sct at maximum, D equals the distance to the nova in pc, and Av is the total galactic absorption of the light path to the nova in V-band magnitudes." A fourth equation, and descriptive text should be added as follows: "The total galactic absorption can be determined by: Av = av ? D (4) where av is the galactic absorption factor of 1.9 V mags/kpc."

Starkey, D.

2008-12-01

340

Combined Photometry and Spectroscopy of Globular Cluster Tidal Streams  

NASA Astrophysics Data System (ADS)

Globular cluster tidal streams are of interest for what they can tell us of the dynamical evolution of the clusters and our Galaxy. Recent studies have used photometric and statistical subtraction methods to attempt to separate potential streams from the field stars that contaminate the samples. We chose instead to use photometry to select blue stars that match the horizontal branch of the clusters and make spectroscopic observations of these candidates to determine their metallicity and radial velocities. Combining these results with the photometric data offers a better picture of the structure and formation of tidal streams. We present preliminary photometric and spectroscopic results for the globular clusters and surrounding fields of NGC 6934, M 10, M 92 and Pal 13. Data obtained at McDonald Observatory, Kitt Peak, and Las Campanas Observatory. WLP acknowledges the support of a Sigma Xi Grant-In-Aid of research, and the Texas Space Grant Consortium Graduate Fellowship. RW acknowledges the support of a AAS Small Research Grant.

Powell, W. L.; Wilhelm, R.; McWilliam, A.; Westfall, A.; Lauchner, A.

2005-12-01

341

CCD time-resolved photometry of faint cataclysmic variables. II  

SciTech Connect

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.

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

342

AK Sco ubvy and Geneva differential photometry (Alencar+, 2003)  

NASA Astrophysics Data System (ADS)

uvby and Geneva photometry of AK Sco obtained between 1987 and 1994 at ESO, La Silla. The file table3a.dat contains 1253 uvby observations obtained with Stroemgren Automatic Telescope (SAT), instrumental system. The transformation coefficients to standard indices can be found in Vaz et al., 1998, Cat. . SAO 208122 was used as primary comparison star and SAO 208143 as secondary comparison star. Standard indices (1994), for SAO 208122 (6 measurements, std errors quoted): V=9.8345+/-0.0022, b-y=0.4506+/-0.0012, m1=0.0958+/-0.0022, c1=0.9355+/-0.0034; for SAO 208143 (3 meas.): V=8.8353+/-0.0024, b-y=0.7193+/-0.0037, m1=0.2903+/-0.0044, c1=0.4670+/-0.0029. File table3b.dat contains 278 observations obtained in 1989 with the Swiss telescope, in the Geneva system. (2 data files).

Alencar, S. H. P.; Melo, C. H. F.; Dullemond, C. P.; Andersen, J.; Batalha, C.; Vaz, L. P. R.; Mathieu, R. D.

2003-09-01

343

Analysis of RGU Photometry in Selected Area 51  

NASA Astrophysics Data System (ADS)

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 color-magnitude diagrams. The unusually large scattering in the two-color 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. [1]. The local logarithmic space density for giants, D*(0)=6.75, lies within the local densities of Gliese and Gliese & Jahreiss. The local luminosity function in our work for the absolute magnitude interval 3

Bilir, S.; Karaali, S.; Buser, R.

2004-09-01

344

NGC 1893 optical and NIR photometry (Prisinzano+, 2011)  

NASA Astrophysics Data System (ADS)

We present new optical and NIR photometric data in the VRIJHK and H-? bands for the cluster NGC 1893. The optical photometry was obtained by using images acquired in service mode using two different telescopes: the Device Optimized for the LOw RESolution (DOLORES) mounted on the Telescopio Nazionale Galileo (TNG), used in service mode during three nights in 2007, and the Calar Alto Faint Object Spectrograph (CAFOS), mounted on the 2.2m telescope in Calar Alto German-Spanish Observatory (Spain), during three nights in 2007 and 2008. NIR observations were acquired in service mode at the TNG, using the large field Near Infrared Camera Spectrometer (NICS) with the Js(1.25um), H(1.63um) and K'(2.12um) filters during eight nights in 2007 and 2008. We observed a field around NGC 1893 with a raster of 4x4 pointings, at each pointing we obtained a series of NINT dithered exposures. Each exposure is a repetition of a DIT (Detector Integration Time) times NDIT (number of DIT), to avoid saturation of the background. (4 data files).

Prisinzano, L.; Sanz-Forcada, J.; Micela, G.; Caramazza, M.; Guarcello, M. G.; Sciortino, S.; Testi, L.

2010-10-01

345

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

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

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

2012-12-14

346

Deep Impact: Optical spectroscopy and photometry obtained at MIRA  

NASA Astrophysics Data System (ADS)

We present spectroscopic and photometric observations, spanning the optical UV to the far red, before, during, and after the NASA Deep Impact event of July 4, 2005. The inner 2000 km of the pre- and post-impact coma was about 0.3 magnitude redder in B-R than in the outer coma. The pre-impact spectrum was a faint reflected solar spectrum dominated by molecular emissions extending >40,000 km from the nucleus. The post-impact light curve in R and I showed a rapid rise consistent with an expanding optically thick cloud during the first 18 min after impact. During the next 8 min the cloud became optically thin. Sixty minutes after impact the impact R-band flux reached a plateau at 7.5×10 ergcmsÅ, the comet brightening by a factor of ˜4.3 above its pre-impact value observed in a 15? aperture. The mean expansion velocity of the grains during the first 49 min was 229±49 ms. The spectrum became dominated by scattered sunlight during the first hour after impact. The volume scattering function (VSF) observed 32 min after impact shows strong reddening. At 49 min, however, the VSF shows an additional twofold increase in the blue but only a 20% increase at 5500 Å. Post-impact spectra and R-I photometry showed rapid reddening. The particle size distribution, dominated by 1-2.5 ?m particles shortly after impact, changed dramatically during the first hour due to sublimation of water-ice particles of this size. On the night following impact the comet was still substantially brighter than before impact, but R-I had returned to its pre-impact value. B-R remained significantly redder. The ejecta 25 h after impact was fan-shaped subtending ˜180° roughly symmetrical about position angle 225°. The mean expansion velocity 90° from the direction to the Sun was 185±12 ms.

Walker, Russell G.; Weaver, Wm. Bruce; Shane, W. W.; Babcock, Arthur

2007-03-01

347

Deep Impact: Optical spectroscopy and photometry obtained at MIRA  

NASA Astrophysics Data System (ADS)

We present spectroscopic and photometric observations, spanning the optical UV to the far red, before, during, and after the NASA Deep Impact event of July 4, 2005. The inner 2000 km of the pre- and post-impact coma was about 0.3 magnitude redder in B R than in the outer coma. The pre-impact spectrum was a faint reflected solar spectrum dominated by molecular emissions extending >40,000 km from the nucleus. The post-impact light curve in R and I showed a rapid rise consistent with an expanding optically thick cloud during the first 18 min after impact. During the next 8 min the cloud became optically thin. Sixty minutes after impact the impact R-band flux reached a plateau at 7.5×10 ergcmsÅ, the comet brightening by a factor of ˜4.3 above its pre-impact value observed in a 15? aperture. The mean expansion velocity of the grains during the first 49 min was 229±49 ms. The spectrum became dominated by scattered sunlight during the first hour after impact. The volume scattering function (VSF) observed 32 min after impact shows strong reddening. At 49 min, however, the VSF shows an additional twofold increase in the blue but only a 20% increase at 5500 Å. Post-impact spectra and R I photometry showed rapid reddening. The particle size distribution, dominated by 1 2.5 ?m particles shortly after impact, changed dramatically during the first hour due to sublimation of water-ice particles of this size. On the night following impact the comet was still substantially brighter than before impact, but R I had returned to its pre-impact value. B R remained significantly redder. The ejecta 25 h after impact was fan-shaped subtending ˜180° roughly symmetrical about position angle 225°. The mean expansion velocity 90° from the direction to the Sun was 185±12 ms.

Walker, Russell G.; Weaver, Wm. Bruce; Shane, W. W.; Babcock, Arthur

348

JHK photometry of Galactic center stars (Ruelas-Mayorga+ 1993)  

NASA Astrophysics Data System (ADS)

We present K-counts and JHK detailed photometry for a number of stars with K<=+9.0 in three clear regions near the galactic centre. These regions are all located approximately at l~0.0 and at latitudes b~-3.5,-4.0 and 4.5 respectively. Their Cumulative Counts Functions (CCF's) are formed, and with the aid of an exponential disk model for the Galaxy they are separated into disk and bulge CCF. As for the case in Baade's Window (BW) (Ruelas-Mayorga & Teague, 1992A&AS...95..379R) the disk is dominant at bright magnitudes whereas the bulge dominates at the faint end of the CCF. The slope of the bulge CCF is steeper than that for the disk in all three cases corroborating the result obtained for BW. The two colour JHK diagram and the K vs J-K diagram for the three regions show that the stellar population in these areas is similar to that studied in BW by us and by Frogel & Whitford (1987ApJ...320..199F). An average value of E(J-K)~0.42mag for the reddening is obtained, which is somewhat larger than that found for BW (0.27). Finally it is shown that at K<=+9.0, the disk population may be accounted for by those sources with J-K<=+1.6 whereas the bulge population presents values for J-K in excess of +1.6. (2 data files).

Ruelas-Mayorga, R. A.; Teague, P. F.

1997-06-01

349

Precision Photometry to Study the Nature of Dark Energy  

SciTech Connect

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.

Lorenzon, Wolfgang; Schubnell, Michael

2011-01-30

350

BVRI photometry of NGC 3231, NGC 7055, and NGC 7127  

NASA Astrophysics Data System (ADS)

Context. Open clusters are often used as tracers for the formation and evolution of the Milky Way. But they can also be used to study distinct "local stellar populations" and all kind of stellar groups. All these studies crucially depend on their unambiguous detection and classification separating them from the fore- and background field population. Aims: Still more than one third of the catalogued galactic open clusters are unstudied to date. We have chosen three northern open cluster fields, namely NGC 3231, NGC 7055, and NGC 7127 which have been never studied before to shed more light on their true nature. Methods: We present Johnson-Cousins BVRI photometry down to V ? 19 mag. After the transformation to the standard systems, colour-magnitude diagrams were generated. These diagrams were used to fit solar abundant isochrones to determine the distance modulus, reddening and apparent age of the main sequences. Results: As reported before, a significant plate-dependent distortion of the UCAC3 compared to the PPMXL within all three star fields was found. No correlation of this distortion with the apparent magnitude of the objects was detected. From the analysis of the colour-magnitude diagrams and the available proper motions we conclude that NGC 7055 and NGC 7127 are young, real, open clusters with ages of about 10 and 100 Myr, respectively. They are located in a distance of about 3300 as well as 5700 pc from the Sun. NGC 3231, on the other hand, is probably a high galactic latitude open cluster remnant. The complete tables with the photometric measurements 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/542/A68

Paunzen, E.; Hermansson, L.; Holmström, P.

2012-06-01

351

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)

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

Quin, D. A.; Doyle, J. G.; Butler, C. J.; Byrne, P. B.; Swank, J. H.

1993-05-01

352

Pesticides in surface water of the Yakima River basin, Washington, 1999-2000; their occurrence and an assessment of factors affecting concentrations and loads  

USGS Publications Warehouse

The occurrence, distribution, and transport of pesticides in surface water of the Yakima River Basin were assessed using data collected during 1999-2000 as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. Samples were collected at 34 sites located throughout the basin in August 1999 using a Lagrangian sampling design. Samples also were collected weekly and monthly from May 1999 through January 2000 at three of the sites. This report includes data for 47 pesticide compounds from the analysis of filtered water using ocadecyl (C-18) solid-phase extraction and gas chromatography/mass spectrometry.Twenty-five pesticide compounds were detected in samples collected during the study. Detection frequencies ranged from about 1 percent for ethalfluralin, ethoprophos, and lindane to 82 percent for atrazine. Maximum concentrations of azinphos-methyl, carbaryl, diazinon, para,para'-dichlorodiphenyldichloroethylene (p,p'-DDE), and lindane exceeded chronic-toxicity guidelines for the protection of freshwater aquatic life. Twenty pesticide compounds were detected during sampling in August 1999. Atrazine was the most widely detected herbicide, and azinphos-methyl was the most widely detected insecticide. The median number of sites at which a particular pesticide compound was detected was six. Pesticide compounds detected at more than six sites include atrazine, simazine, terbacil, trifluralin, deethylatrazine, azinphos-methyl, carbaryl, diazinon, malathion, and p,p'-DDE.Because many factors affect the transport of pesticides from areas of application to surface water, there was not a simple correspondence between pesticide occurrence and use in the Yakima River Basin. For example, the high detection rates of atrazine, simazine, deethylatrazine, and p,p'-DDE are probably related more to their mobility and wide distribution in the hydrologic system than to their usage. Likewise, higher detection frequencies of the insecticides azinphos-methyl and carbaryl compared with chlorpyrifos appear to be related more to differences in their physical and chemical properties than to usage.The highest detection frequencies and concentrations of pesticides generally occurred during irrigation season, which is from mid-March to mid-October. Pesticides are applied during irrigation season, and runoff of excess irrigation water from fields transports them to surface water.Ground-water discharges also transport some pesticides to surface water. Atrazine, deethylatrazine, and simazine were frequently detected in samples collected after the irrigation season when there was little or no surface runoff and most of the flow in irrigation drains was derived from ground water.Daily loads of atrazine, terbacil, azinphos-methyl, and carbaryl discharged to the Yakima River from inflows between river mile 103.7 and river mile 72 varied widely between sites. For example, East Toppenish Drain discharged over 50 percent of the total load of terbacil to this reach of the Yakima River, but none of the total load of carbaryl and only about 4 percent of the total load of atrazine. Pesticide loads from the wastewater treatment plants were relatively small compared with loads from other inflows because their discharges were small.Pesticide losses, defined as the ratio of the amount discharged from a basin from May 1999 through January 2000 divided by the amount applied during 1999, were estimated for Moxee and Granger Drains and the Yakima River at Kiona. Losses ranged from less than 0.01 to 1.5 percent of pesticides applied and are comparable to those observed (0.01 to 2.2 percent) in irrigated agricultural basins in the Central Columbia Plateau of Washington State.

Ebbert, James C.; Embrey, Sandra S.

2002-01-01

353

Spot activity on HD 89546 (FG UMa) from long-term photometry  

NASA Astrophysics Data System (ADS)

We present the analysis of 20 years of time-series BV photometry of the SB1 RS CVn binary HD 89546. The system's yearly mean V brightness, the B-V color index, the photometric period, and the light curve amplitude all show clear cyclic variability with an ?9-year time scale. We also find some evidence for brightness variability on a time scale longer than the 20-year time span of our observations, perhaps indicating a longer cycle analogous to the solar Gleissberg cycle. We estimate the unspotted V magnitude of HD 89546 to be 7.154m, which is ?0.2m brighter than the observed maximum brightness. Spot modelling of the system shows that spot temperature variations affect the observed B-V color as well as the V brightness. Two active longitudes are observed, centered around 180° and 360° longitude on the G9 III primary, each covering a longitude range of 120°. Furthermore, two inactive longitude zones are seen spanning only 60° between the two active longitudes. The longitudinal distribution of the spots exhibits no strong cyclic variability but does show rapid jumps of 120° that look like the flip-flop phenomenon. We estimate the differential rotation coefficient of the star as k=0.086 by considering the range of observed photometric period variations and assumed latitudinal spot variations over 45°. Based on data obtained with the Tennessee State University T3 0.4 m APT at Fairborn Observatory, operated by Tennessee State University, and T30 0.3 m telescope of the Ege University Observatory in Izmir.

Özdarcan, O.; Evren, S.; Henry, G. W.

2012-02-01

354

Optical properties of boreal forest fire smoke derived from Sun photometry  

NASA Astrophysics Data System (ADS)

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 (?a) statistics for Waskesiu, Saskatchewan, and Thompson, Manitoba, were analyzed for summer data acquired between 1994 and 1999. A significant correlation between the geometric mean and the forest fire frequency indices (hot spots) was found; on the average, 80% of summertime optical depth variation in western Canada can be linked to forest fire sources. The average geometric mean and geometric standard deviation at 500 nm was observed to be 0.074 and 1.7 for the clearest, relatively smoke-free summer and 0.23 and 3.0 for the summer most influenced by smoke. A systematic decrease of fine mode Angstrom exponent (?f) was noted (d?f /d log ?a ~ -0.6). This decrease roughly corresponds to an increase in the fine mode effective radius (reff) from 0.09 to 0.15 ?m and an abundance (A) to size rate increase near 2.0 (d log A / d log reff). A 1998 series of forest fire events was tracked using TOMS, AVHRR, and GOES imagery, back trajectories, and data from six Sun photometer sites in Canada and eastern United States. The results showed rates of decrease of ?f with increasing ?a which were similar to the climatological data. An analysis in terms of source to station distance showed a decrease in ?f and an increase in reff with increasing distance. This observation was coherent with previous observations on the particle growth effects of aging.

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

2002-06-01

355

Multicolor Photometry and Time-resolved Spectroscopy of Two sdBV Stars  

NASA Astrophysics Data System (ADS)

Observational mode constraints have mostly been lacking for short period pulsating sdB stars, yet such identifications are vital to constrain models. Time-resolved spectroscopy and multicolor photometry have been employed with mixed results for short-period pulsating sdB stars. Time-resolved spectroscopy has successfully measured radial velocity, temperature, and gravity variations in six pulsators, yet interpreting results is far from straightforward. Multicolor photometry requires extremely high precision to discern between low-degree modes, yet has been used effectively to eliminate high-degree modes. Combining radial velocity (RV) and multicolor measurements has also been shown as an effective means of constraining mode identifications. We present preliminary results for Feige 48 and EC 01541-1409 using both time-resolved spectroscopy and multicolor photometry and an initial examination of their pulsation modes using the atmospheric codes BRUCE and KYLIE.

Reed, M. D.; O'Toole, S. J.; Telting, J. H.; Østensen, R. H.; Heber, U.; Barlow, B. N.; Reichart, D. E.; Nysewander, M. C.; LaCluyze, A. P.; Ivarsen, K. M.; Haislip, J. B.; Bean, J.

2012-03-01

356

Near-nucleus photometry of comets using archived NEAT data  

NASA Astrophysics Data System (ADS)

Though optimized to discover and track fast moving Near-Earth Objects (NEOs), the Near-Earth Asteroid Tracking (NEAT) survey dataset can be mined to obtain information on the comet population observed serendipitously during the asteroid survey. We have completed analysis of over 400 CCD images of comets obtained during the autonomous operations of two 1.2-m telescopes: the first on the summit of Haleakala on the Hawaiian island of Maui and the second on Palomar Mountain in southern California. Photometric calibrations of each frame were derived using background catalog stars and the near-nucleus comet photometry measured. We measured dust production and normalized magnitudes for the coma and nucleus in order to explore cometary activity and comet size-frequency distributions. Our data over an approximately two-year time frame (2001 August-2003 February) include 52 comets: 12 periodic, 19 numbered, and 21 non-periodic, obtained over a wide range of viewing geometries and helio/geocentric distances. Nuclear magnitudes were estimated for a subset of comets observed. We found that for low-activity comets ( Af?<100 cm) our model gave reasonable estimates for nuclear size and magnitude. The slope of the cumulative luminosity function of our sample of low-activity comets was 0.33 ± 0.04, consistent with the slope we measured for the Jupiter-family cometary nuclei collected by Fernández et al. [Fernández, J.A., Tancredi, G., Rickman, H., Licandro, J., 1999. Astron. Astrophys. 392, 327-340] of 0.38 ± 0.02. Our slopes of the cumulative size distribution ?=1.50±0.08 agree well with the slopes measured by Whitman et al. [Whitman, K., Morbidelli, A., Jedicke, R., 2006. Icarus 183, 101-114], Meech et al. [Meech, K.J., Hainaut, O.R., Marsden, B.G., 2004. Icarus 170, 463-491], Lowry et al. [Lowry, S.C., Fitzsimmons, A., Collander-Brown, S., 2003. Astron. Astrophys. 397, 329-343], and Weissman and Lowry [Weissman, P.R., Lowry, S.C., 2003. Lunar Planet. Sci. 34. Abstract 34].

Hicks, Michael D.; Bambery, Raymond J.; Lawrence, Kenneth J.; Kollipara, Priya

2007-06-01

357

High-precision ground-based photometry of exoplanets  

NASA Astrophysics Data System (ADS)

High-precision photometry of transiting exoplanet systems has contributed significantly to our understanding of the properties of their atmospheres. The best targets are the bright exoplanet systems, for which the high number of photons allow very high signal-to-noise ratios. Most of the current instruments are not optimised for these high-precision measurements, either they have a large read-out overhead to reduce the readnoise and/or their field-of-view is limited, preventing simultaneous observations of both the target and a reference star. Recently we have proposed a new wide-field imager for the Observatoir de Mont-Megantic optimised for these bright systems (PI: Jayawardhana). The instruments has a dual beam design and a field-of-view of 17' by 17'. The cameras have a read-out time of 2 seconds, significantly reducing read-out overheads. Over the past years we have obtained significant experience with how to reach the high precision required for the characterisation of exoplanet atmospheres. Based on our experience we provide the following advice: Get the best calibrations possible. In the case of bad weather, characterise the instrument (e.g. non-linearity, dome flats, bias level), this is vital for better understanding of the science data. Observe the target for as long as possible, the out-of-transit baseline is as important as the transit/eclipse itself. A short baseline can lead to improperly corrected systematic and mis-estimation of the red-noise. Keep everything (e.g. position on detector, exposure time) as stable as possible. Take care that the defocus is not too strong. For a large defocus, the contribution of the total flux from the sky-background in the aperture could well exceed that of the target, resulting in very strict requirements on the precision at which the background is measured.

de Mooij, Ernst J. W.; Jayawardhana, Ray

2013-04-01

358

Temperature mapping of sunspots and pores from speckle reconstructed three colour photometry  

NASA Astrophysics Data System (ADS)

The two-dimensional temperature distribution in a highly structured sunspot and in two small umbrae is determined from a three-colour photometry in narrow spectral continua. Disturbing influences from the earth's atmosphere are removed by speckle masking techniques, yielding a spatial resolution limited by the telescope's aperture. The corresponding colour temperatures are consistent over a range of more than 2000 K, although the numerical correction introduced by the reconstruction differs largely for the three colours. Part of the scatter in the temperature relation disappears when convoluting the final images with artificial PSFs that compensate for the different, colour dependent spatial resolution. The remaining spread in the scatter plots does not reflect noise, but is related to local variations of the temperature difference between the continuum emitting layers. This is most obvious for a small umbra which yields `branches' in the scatter plots the `bluer' of which corresponding to the limb-side umbral border. Here, the `hot rim' of a Wilson depressed umbra becomes visible. The temperature map of the large spot shows that the bright umbral dots do not reach the temperature of the non-spot surroundings. Instead, they exceed the 2000 K cooler umbral temperature minimum by 900-1300 K. The filamentary structure of the surrounding penumbra has spatial temperature fluctuations of typically 700 K, a value which fits earlier observed contrasts. However, the mean temperatures of 5650 K in the dark and 6250 K in the bright penumbral fine structures exceed former findings. Exceptionally bright penumbral grains are 250 K hotter than the mean solar surface and thus exceed even brightest granules.

Suetterlin, P.; Wiehr, E.

1998-08-01

359

Time-series BVI Photometry for the Globular Cluster NGC 6981  

NASA Astrophysics Data System (ADS)

We present new BVI photometry of the globular cluster NGC 6981, based mostly on ground-based CCD archival images. We present a new color-magnitude diagram (CMD) that reaches almost four magnitudes below the turn-off level. We performed new derivations of metallicity and morphological parameters of the evolved sequences, in good agreement with the results of previous authors, and obtain a value of [Fe/H] ~= –1.50 in the new UVES scale. We also identify the cluster's blue straggler population. Comparing the radial distribution of these stars with the red giant branch population, we find that the blue stragglers are more centrally concentrated, as found in previous studies of blue stragglers in globular clusters. Taking advantage of the large field of view covered by our study, we analyzed the surface density profile of the cluster, and find extratidal main sequence stars out to r ? 14.'1, or about twice the tidal radius. We speculate that the presence of these stars may be due to tidal disruption in the course of NGC 6981's orbit, in which case tidal tails associated with the cluster may exist. We also take a fresh look at the variable stars in the cluster, recovering all previously known variables, including three SX Phoenicis stars. We also add three previously unknown RR Lyrae (one c-type and two ab-type) to the total census. Finally, comparing our CMD with unpublished data for M3 (NGC 5272), a cluster with a similar metallicity and horizontal branch morphology, we found that both objects are essentially coeval. This paper makes use of data obtained from the Isaac Newton Group Archive, which is maintained as part of the CASU Astronomical Data Centre at the Institute of Astronomy, Cambridge.

Amigo, P.; Stetson, P. B.; Catelan, M.; Zoccali, M.; Smith, H. A.

2013-11-01

360

Stellar Populations of Dwarf Elliptical Galaxies: UBVRI Photometry of Dwarf Elliptical Galaxies in the Virgo Cluster  

NASA Astrophysics Data System (ADS)

We present UBVRI surface photometry for 16 dwarf elliptical galaxies in the Virgo Cluster with previously measured kinematic properties. The global optical colors are red, with median values for the sample of 0.24+/-0.03 in U-B, 0.77+/-0.02 in B-V, and 1.02+/-0.03 in V-I. We recover the well-known color-magnitude relation for cluster galaxies but find no significant difference in dominant stellar population between rotating and nonrotating dwarf elliptical galaxies; the average age of the dominant stellar population is 5-7 Gyr in all 16 galaxies in this sample. Analysis of optical spectra confirm these age estimates and indicate Fe and Mg abundances in the range of 1/20 to one-third of solar, as expected for low-luminosity galaxies. Based on Lick indices and simple stellar population models, the derived [?/Fe] ratios are subsolar to solar, indicating a more gradual chemical enrichment history for dE's as compared with giant elliptical galaxies in the Virgo Cluster. These observations confirm the marked difference in stellar population and stellar distribution between dwarf and giant elliptical galaxies and further substantiate the need for alternative evolutionary scenarios for the lowest mass cluster galaxies. We argue that it is likely that several different physical mechanisms played a significant role in the production of the Virgo Cluster dE galaxies including in situ formation, infall of dE's that were once part of Local Group analogs, and transformation of dwarf irregular galaxies by the cluster environment. The observations support the hypothesis that a large fraction of the Virgo Cluster dE's are formed by ram pressure stripping of gas from infalling dI's. Based on observations with the VATT: the Alice P. Lennon Telescope and the Thomas J. Bannan Astrophysics Facility.

van Zee, Liese; Barton, Elizabeth J.; Skillman, Evan D.

2004-12-01

361

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

SciTech Connect

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

Siegel, Michael H.; Hoversten, Erik A.; Roming, Peter W. A.; Brown, Peter, E-mail: siegel@astro.psu.ed, E-mail: hoversten@astro.psu.ed, E-mail: roming@astro.psu.ed, E-mail: brown@astro.psu.ed [Department of Astronomy, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

2010-12-10

362

Precision of a Low-Cost InGaAs Detector for Near Infrared Photometry  

NASA Astrophysics Data System (ADS)

We have designed, constructed, and tested an InGaAs near-infrared camera to explore whether low-cost detectors can make small (? 1 m) telescopes capable of precise (< 1 mmag) infrared photometry of relatively bright targets. The camera is constructed around the 640 × 512 pixel APS640C sensor built by FLIR Electro-Optical Components. We designed custom analog-to-digital electronics for maximum stability and minimum noise. The InGaAs dark current halves with every 7°C of cooling, and we reduce it to 840 e- s-1 pixel-1 (with a pixel-to-pixel variation of ± 200 e- s-1 pixel-1) by cooling the array to -20°C. Beyond this point, glow from the readout dominates. The single-sample read noise of 149 e- is reduced to 54 e- through up-the-ramp sampling. Laboratory testing with a star field generated by a lenslet array shows that two-star differential photometry is possible to a precision of 631 ± 205 ppm (0.68 mmag) hr-1/2 at a flux of 2.4 × 104 e- s-1. Employing three comparison stars and decorrelating reference signals further improves the precision to 483 ± 161 ppm (0.52 mmag) hr-1/2. Photometric observations of HD80606 and HD80607 (J = 7.7 and 7.8) in the Y band shows that differential photometry to a precision of 415 ppm (0.45 mmag) hr-1/2 is achieved with an effective telescope aperture of 0.25 m. Next-generation InGaAs detectors should indeed enable Poisson-limited photometry of brighter dwarfs with particular advantage for late-M and L types. In addition, one might acquire near-infrared photometry simultaneously with optical photometry or radial velocity measurements to maximize the return of exoplanet searches with small telescopes.

Sullivan, Peter W.; Croll, Bryce; Simcoe, Robert A.

2013-09-01

363

Near-Infrared Photometry and Spectroscopy of L and T Dwarfs: The Effects of Temperature, Clouds, and Gravity  

Microsoft Academic Search

We present new JHK photometry on the MKO-NIR system and JHK spectroscopy for a large sample of L and T dwarfs. Photometry has been obtained for 71 dwarfs, and spectroscopy for 56. The sample comprises newly identified very red objects from the Sloan Digital Sky Survey (SDSS) and known dwarfs from the SDSS and the Two Micron All Sky Survey

S. K. Leggett; X. Fan; M. S. Marley; T. R. Geballe; D. A. Golimowski; D. Finkbeiner; J. E. Gunn; J. Hennawi; Z. Ivezic; R. H. Lupton; D. J. Schlegel; M. A. Strauss; Z. I. Tsvetanov; K. Chiu; E. A. Hoversten; K. Glazebrook; W. Zheng; M. Hendrickson; C. C. Williams; A. Uomoto; F. J. Vrba; A. A. Henden; C. B. Luginbuhl; H. H. Guetter; B. Canzian; Donald P. Schneider; J. Brinkmann

2004-01-01

364

U - B - V photometry of the spectroscopic-visual triple HD 165590  

Microsoft Academic Search

HD 165590 is a visual binary (dG0 + dG5,P = 20.y25,e = 0.96) whoseA component is an SB1 double (dG5 + dM:P = 0.d88,e˜0.0). TheA pair (Aa +Ab) undergoes partial eclipses. PhotoelectricUBV photometry from Lines and one of the Automatic Photoelectric Telescopes, andV photometry from Scarfe are examined here. The data are from the 1977, 1984, 1985, and 1986 observing

J. R. Bruton; D. S. Hall; L. J. Boyd; R. M. Genet; R. D. Lines; H. C. Lines; C. D. Scarfe

1989-01-01

365

Optical studies of southern clusters of galaxies. III - Photoelectric photometry of galaxies in 15 clusters  

NASA Astrophysics Data System (ADS)

Multiaperture g and r photoelectric photometry is presented for 48 galaxies in the clusters: A85, A119, SC0316 - 344, SC0342 - 538, Sersic 40/6, SC0626 - 547, A754, A1146, Klemola 21, SC1329 - 314, SC1326 - 311, A2052, SC2008 - 569, SC2059 247, Klemola 44. The data are mainly intended for the calibration of photographic plates and the existence of a linear transformation to the UBV system make them useful to workers using plates taken in the B or V bands. A compilation of published photoelectric photometry on these clusters is given and a detailed comparison between these and other observations is presented.

Melnick, J.; Quintana, H.

1984-09-01

366

Epoxi Exoplanet Transit Obs - Hriv Stellar Photometry V1.0  

NASA Astrophysics Data System (ADS)

This data set contains aperture photometry of known transiting planet systems GJ 436, HAT-P-4, HAT-P-7, TrES-2, TrES-3, and WASP-3 derived from radiance calibrated, clear #6 filtered images acquired by the Deep Impact High Resolution Visible CCD from 22 January through 31 August 2008 during the EPOCh phase of the EPOXI mission. The photometry data were derived from time series of continuous 50-second integrations used to observe each system for about three weeks, typically covering five or more transits as well as secondary eclipses.

Christiansen, J. L.; Ballard, S.; Deming, D.; Charbonneau, D.; Wellnitz, D. D.; McLaughlin, S. A.

2012-01-01

367

RIK photometry of far-IR sources in NGP (Vaisanen+, 2010)  

NASA Astrophysics Data System (ADS)

Table A.2 lists the full photometric catalog of the ISOPHOT EBL project North Galactic Pole fields acquired with the Nordic Optical Telescope, using the ALFOSC (in R and I band) and NOTCAM (in K band) instruments. The photometry is performed with SExtractor and both "total" and aperture magnitudes are given using the AUTO and APER (with 2.7" diameter) magnitudes, as well as the star/galaxy CLASS parameter. The photometry is matched with the SDSS and the ugriz magnitudes are also given. All objects falling within 60" of a given ISOPHOT far-IR source are indicated - these areas are analysed in the Paper. (2 data files).

Vaisanen, P.; Kotilainen, J. K.; Juvela, M.; Mattila, K.; Efstathiou, A.; Kahanpaa, J.

2010-03-01

368

Near-infrared photometry of Galactic planetary nebulae with the VVV Survey.  

NASA Astrophysics Data System (ADS)

Aperture photometry of known PNe in the VVV area was retrieved from source catalogues. 579 PNe were selected from the VVV (VISTA Variables in the Via Lactea) survey catalogue. Of these 353 present near-infrared photometry, 75 are highly extended sources, and 123 PNe could not be related to any source in the VVV images, the remainder are sources which NIR emission of the PN is detected in the frames, but there are no photometric data in the VSA database. (3 data files).

Weidmann, W. A.; Gamen, R.; van Hoof, P. A. M.; Zijlstra, A.; Minniti, D.; Volpe, M. G.

369

Photometry of the Newly-Discovered SU UMa Star in Taurus  

NASA Astrophysics Data System (ADS)

We report the results of time-resolved CCD photometry obtained with the Mount Laguna Observatory 1-m reflector of the recently-discovered variable star in Taurus (CBET #701). A total of ~20 hours of V-band photometry over six nights (2006 Oct 28 - 30; 2006 Nov 01 - 03) has enabled us to confirm its tentative identification as a previously unknown SU UMa dwarf nova, and to establish a revised superhump period of 0.05338(1) days (76.87 min).

Shafter, A. W.; Coelho, E. A.; Reed, J. K.

2006-11-01

370

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

PubMed Central

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.

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

2011-01-01

371

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

PubMed Central

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.

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

2011-01-01

372

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)

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.

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

2003-03-01

373

UBVRI photometry of faint field stars (Skiff, 2007)  

NASA Astrophysics Data System (ADS)

This file, originally prepared for the needs of the Lowell Observatory Near-Earth Object Search (LONEOS), contains a rough working collection of Johnson-Cousins UBVRI photometry assembled mainly from the published literature or from publicly available datasets. The V-R and V-I colors are all on the Cousins system. Most of the stars are fainter than V=10.0; the median magnitude is V=13.9, and significant numbers of stars are listed below 20mag. Besides several large surveys, several hundred small sequences in the regions of variable stars, star clusters, galaxies hosting supernovae, quasars, etc were built by determining coordinates for the sequence stars using the published finder charts. At minimum the data include V magnitudes and at least one ordinary photometric color, most commonly B-V. The data were collected for use in determining approximate photometric zero-points in wide-field imaging, with external accuracy of 0.05 mag or better. Though each dataset was vetted for consistency in magnitude and colors, neither high accuracy nor high precision is guaranteed. Obvious variable stars were omitted, but some unknown variables are inevitably included. In any given field, it is advisable use all the available stars for calibration rather than a single comparison. Several large datasets are included. The Guide Star Photometric Catalogue (GSPC, Lasker et al 1988, Cat. II/143) provides BV sequences near the centers of all the Schmidt sky survey plates. At high latitudes in the southern sky, additional data on the 5-degree Schmidt grid were obtained by Platais et al (1998, Cat. I/277) that extend the GSPC sequences to V=~16. More southern fields were observed by Demers et al (1993A&AS...99..437D and 1993A&AS...99..461D); coordinates for these stars have been determined for the first time. Nearly a thousand high-quality sequences in the northern sky have been observed by Henden, partly published in relation to work on cataclysmic variables (e.g. Cat. J/PASP/107/324) and symbiotic stars (e.g. Cat. J/A+A/143/343). Additional Henden sequences have been adopted from the files cited below at the AAVSO ftp site. These large sequences were trimmed to include only a few stars per magnitude interval, and also to omit crowded stars (no significant companions closer than 15" radius). The star coordinates are mainly from early versions of the GSC or USNO series. As such they are given to 1" precision, and in some cases small systematic errors and (now) proper motion mean their accuracy is in the 1" to 5" range. Thus for automated linkage to CCD frames, some modest search radius should be adopted to match with the catalogue. Because the file was originally intended for private use, bibliographic references were not included except in a very few instances. Usually it is straightforward to recover the source paper by inspection of the SIMBAD bibliography for specific objects. Problematic cases can be directed to the compiler (Brian Skiff). (1 data file).

Skiff, B. A.

2007-03-01

374

Integrated UBV Photometry of 624 Star Clusters and Associations in the Large Magellanic Cloud  

Microsoft Academic Search

We present a catalog of integrated UBV photometry of 504 star clusters and 120 stellar associations in the LMC, part of them still embedded in emitting gas. We study age groups in terms of equivalent SWB types derived from the (U-B) X (B-V) diagram. The size of the spatial distributions increases steadily with age (SWB types), whereas a difference of

E. Bica; J. J. Claria; H. Dottori; J. F. C. Santos Jr.; A. E. Piatti

1996-01-01

375

Photometry of SDSS J152419.33+220920.0 (Michel+, 2013)  

NASA Astrophysics Data System (ADS)

We present new photometry of the faint (g~19mag) and poorly studied cataclysmic variable SDSS J152419.33+220920.0, analyze its light curve and provide an accurate ephemeris for this system. Time-resolved CCD differential photometry was carried out using the 1.5m and 0.84m telescopes at the Observatorio Astronomico Nacional at San Pedro Martir. All observations were taken in white-light (no filter). This table contains the differential photometry for the system obtained during six nights (covering more than twenty primary eclipse cycles in more than three years). The reference for the photometry is SDSS J152415.99+220804.0, g=17.77 (marked as star C1 in the paper). The associated errors are 0.02mag outside eclipse. The information for each observation run is presented in Table 1 and the light-curves using this data are presented in Figure 4. Our light curve analysis shows that only two fundamental frequencies are present, corresponding to the orbital period and a modulation with twice this frequency. We determine the accurate ephemeris of the system to be HJDeclipse=2454967.6750(1)+0.06531866661(1)E. A double-hump orbital period modulation, a standing feature in several bounce-back systems at quiescence, is present at several epochs. However, we found no other evidence to support the hypothesis that this system belongs to the post-minimum orbital-period systems. (2 data files).

Michel, R.; Echevarria, J.; Hernandez Santisteban, J. V.

2013-04-01

376

Disk-Resolved Photometry of Cometary Nuclei: Results from DIXI and Stardust-NExT  

NASA Astrophysics Data System (ADS)

We report detailed studies of the photometric properties of two cometary nuclei, 103P/Hartley 2 and 9P/Tempel 1, from DIXI flyby and Stardust-NExT flyby, respective, and the comparative studies of cometary nucleus photometry.

Li, J.-Y.; A'Hearn, M. F.; Besse, S.; Belton, M. J. S.; Farnham, T. L.; Klaasen, K. P.; Lisse, C. M.; McFadden, L. A.; Sunshine, J. M.; Thomas, P. C.; Veverka, J.

2012-05-01

377

A Tight Upper Limit on Oscillations in the Ap Star ? Ursae Majoris from WIRE Photometry  

Microsoft Academic Search

Observations of ? UMa obtained with the star tracker on the Wide Field Infrared Explorer satellite during a month in mid-2000 are analyzed. This is some of the most precise photometry of an Ap star. The amplitude spectrum is used to set an upper limit of 75 parts per million for the amplitude of stellar pulsations in this star unless

Alon Retter; Timothy R. Bedding; Derek L. Buzasi; Hans Kjeldsen; László L. Kiss

2004-01-01

378

Thermal Emission Photometry of Deep Impact Flyby Target (163249) 2002 GT  

NASA Astrophysics Data System (ADS)

Near-Earth asteroid (163249) 2002 GT is now the target of a Deep Impact spacecraft flyby in Jan. 2020 (see Pittichova et al., this volume, for details of the flyby and observing campaign). Thermal emission photometry of 2002 GT was obtained from NIRI on Gemini-North in the L' and M' filters, which are centered at 3.76 and 4.68 microns respectively. J- and K-band reflectance photometry was also acquired in support of the thermal observations. The full JKL'M' set was acquired on UT 2013-Jun-13 at a solar phase angle of 53 degrees. A further set of photometry in J, K, and L' only was carried out on 2013-Jun-19 at a phase angle of 65 degrees. High water vapor conditions at Mauna Kea during this period unfortunately prevented acquisition of a second set of M' measurements. In addition, N-band photometry of 2002 GT was conducted on 2013-Jun-10 from CanariCam at the 10-meter Gran Telescopio Canarias using a beta version of the moving object guiding system. Data were acquired in three filters between 8.7 and 12.5 microns, although the limitations of the guiding are complicating the analysis. (We note that N-band observing was not offered by either Gemini or IRTF during this apparition.) Data analysis is ongoing and results will be discussed. We appreciate the efforts of the Gemini and GTC staff in support of these observing programs.

Lim, Lucy F.; Moskovitz, N. A.; Licandro, J.; Emery, J. P.; Reddy, V.; Vilas, F.; 2002 GT Observing Team

2013-10-01

379

The MATPHOT Algorithm for Accurate and Precise Stellar Photometry and Astrometry Using Discrete Point Spread Functions  

Microsoft Academic Search

I describe the key features of my MATPHOT algorithm for accurate and precise stellar photometry and astrometry using discrete Point Spread Functions. A discrete Point Spread Function (PSF) is a sampled version of a continuous two-dimensional PSF. The shape information about the photon scattering pattern of a discrete PSF is typically encoded using a numerical table (matrix) or a FITS

K. J. Mighell

2004-01-01

380

The R Coronae Borealis stars - I. Infrared photometry and long-term variations  

Microsoft Academic Search

Extensive JHKL photometry is given for 12 R Coronae Borealis (RCB) stars, covering periods of up to 23 years. Limited infrared observations of a few other RCB stars and five HdC stars are also reported. These data are used to study the long-term variations of the stars (at J) and of the circumstellar dust (at L). All of the RCB

M. W. Feast; B. S. Carter; G. Roberts; F. Marang; R. M. Catchpole

1997-01-01

381

Physical studies of asteroids. XXV - Photoelectric photometry of asteroids obtained at ESO and Hoher List Observatory  

NASA Astrophysics Data System (ADS)

Photoelectric photometry of 14 asteroids, carried out at ESO and the Hoher List Observatory during 1990 and 1991, are presented. Composite lightcurves were derived for the asteroids 140 Siwa, 238 Hypatia, 347 Pariana, 389 Industria and 1593 Fagnes. UBV colors are also given for ten of the asteroids.

Lagerkvist, C.-I.; Magnusson, P.; Debehogne, H.; Hoffmann, M.; Erikson, A.; de Campos, A.; Cutispoto, G.

1992-11-01

382

An Updated Catalog of M33 Clusters and Candidates: UBVRI Photometry and Some Statistical Results  

NASA Astrophysics Data System (ADS)

We present UBVRI photometry for 392 star clusters and candidates in the field of M33, which are selected from the most recent star cluster catalog. In this catalog, the authors listed star clusters' parameters such as cluster positions, magnitudes, colors in the UBVRIJHKs filters, and so on. However, a large fraction of objects in this catalog do not have previously published photometry. Photometry is performed using archival images from the Local Group Galaxies Survey, which covers 0.8 deg2 along the major axis of M33. Detailed comparisons show that, in general, our photometry is consistent with previous measurements. Positions (right ascension and declination) for some clusters are corrected here. Combined with previous literature, ours constitute a large sample of M33 star clusters. Based on this cluster sample, we present some statistical results: none of the youngest M33 clusters (~107 yr) have masses approaching 105 M ? roughly half the star clusters are consistent with the 104-105 M ? mass models; the continuous distribution of star clusters along the model line indicates that M33 star clusters have been formed continuously from the epoch of the first star cluster formation until recent times; and there are ~50 star clusters which are overlapped with the Galactic globular clusters on the color-color diagram, and these clusters are old globular cluster candidates in M33.

Ma, Jun

2012-08-01

383

Narrowband Photometry of Comet P\\/Halley: Variation with Heliocentric Distance, Season, and Solar Phase Angle  

Microsoft Academic Search

Narrowband filter photometry of Comet P\\/Halley from 109 nights in 1985, 1986, and 1987 is analyzed to discern the comet's variation in activity with changing heliocentric distance and season. The scattering phase function of dust in the coma is also investigated. Asymmetry about perihelion in the production of gas and dust is confirmed. However, we find the asymmetry to be

David G. Schleicher; Robert L. Millis; Peter V. Birch

1998-01-01

384

Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory  

Microsoft Academic Search

We present photometric and astrometric results for 36 binary systems observed with the natural guide star adaptive optics system of the Mount Wilson Institute on the 100 inch (2.5 m) Hooker Telescope. The measurements consist of differential photometry in U, B, V, R, and I filters along with astrometry of the relative positions of system components. Magnitude differences were combined

Theo ten Brummelaar; Brian D. Mason; Harold A. McAlister; Lewis C. Roberts Jr.; Nils H. Turner; William I. Hartkopf; William G. Bagnuolo Jr.

2000-01-01

385

Photometry of P\\/Halley (1982i) at Catania (Italy) Observatory  

Microsoft Academic Search

Photoelectric photometry of the Halley comet has been carried out at the 91 cm telescope of the Catania Astrophysical Observatory using the C2, C3, CN, BC and UC IHW Standard filters. To compute the gas production rates of the C2, C3, CN molecules the authors used the Haser model; they computed the production rates of solids too, that are supposed

F. A. Catalano; G. A. Baratta; C. Lopresti; G. Strazzulla

1986-01-01

386

Spectral Fluorescence Efficiencies of certain Substances with Applications to Heterochromatic Photographic Photometry  

Microsoft Academic Search

In extending the method of fluorescence photographic photometry recently described by the writers from homochromatic to heterochromatic usefulness, experiments have been carried out on the efficiencies of fluorescence of various substances in the visible and ultraviolet regions. A number of substances fluorescing at wavelengths between the red and the ultraviolet have been tested, and many of these have been found

George R. Harrison; Philip A. Leighton

1931-01-01

387

SPIRE point source photometry: within the Herschel interactive processing environment (HIPE)  

NASA Astrophysics Data System (ADS)

The different algorithms appropriate for point source photometry on data from the SPIRE instrument on-board the Herschel Space Observatory, within the Herschel Interactive Processing Environment (HIPE) are compared. Point source photometry of a large ensemble of standard calibration stars and dark sky observations is carried out using the 4 major methods within HIPE: SUSSEXtractor, DAOphot, the SPIRE Timeline Fitter and simple Aperture Photometry. Colour corrections and effective beam areas as a function of the assumed source spectral index are also included to produce a large number of photometric measurements per individual target, in each of the 3 SPIRE bands (250, 350, 500?m), to examine both the accuracy and repeatability of each of the 4 algorithms. It is concluded that for flux densities down to the level of 30mJy that the SPIRE Timeline Fitter is the method of choice. However, at least in the 250 and 350?m bands, all 4 methods provide photometric repeatability better than a few percent down to at approximately 100mJy. The DAOphot method appears in many cases to have a systematic offset of ˜8 % in all SPIRE bands which may be indicative of a sub-optimal aperture correction. In general, aperture photometry is the least reliable method, i.e. largest scatter between observations, especially in the longest wavelength band. At the faintest fluxes, <30mJy, SUSSEXtractor or DAOphot provide a better alternative to the Timeline Fitter.

Pearson, Chris; Lim, Tanya; North, Chris; Bendo, George; Conversi, Luca; Dowell, Darren; Griffin, Matt; Jin, Terry; Laporte, Nicolas; Papageorgiou, Andreas; Schulz, Bernhard; Shupe, Dave; Smith, Anthony J.; Xu, Kevin

2013-10-01

388

Wide-field photometry at 20 Hz for the TAOS II Project  

NASA Astrophysics Data System (ADS)

The TAOS II Project requires high-speed differential photometry of 10-20 thousand stars over a telescope field of 154mm diameter with 16-micron spatial resolution and good noise performance. We are developing a custom CMOS imager array to accomplish this task.

Geary, John C.; Wang, Shiang-Yu; Lehner, Matthew J.; Jorden, Paul; Fryer, Martin

2012-09-01

389

Diffuse light corrections to Sun photometry of desert dust and marine aerosols  

Microsoft Academic Search

The NASA Ames airborne Sun photometry program has benefited in many ways from the work of John Reagan. Our water vapor retrieval methods are based on methods published by Prof. Reagan (1987). Designs for our existing instruments and advanced concepts have been influenced by Prof. Reagan's instruments and by his specialized consulting. And our measurements of the Pinatubo volcanic stratospheric

P. B. Russell; J. M. Livingston; O. Dubovik; S. A. Ramirez; J. Wang; J. Redemann; B. Schmid; M. Box; B. N. Holben

2005-01-01

390

Sunlight transmission through desert dust and marine aerosols: Diffuse light corrections to Sun photometry and pyrheliometry  

Microsoft Academic Search

Desert dust and marine aerosols are receiving increased scientific attention because of their prevalence on intercontinental scales and their potentially large effects on Earth radiation, climate, other aerosols, clouds, and precipitation. The relatively large size of dust and marine aerosol particles produces scattering phase functions that are strongly forward peaked. Hence Sun photometry and pyrheliometry of these aerosols are more

P. B. Russell; J. M. Livingston; O. Dubovik; S. A. Ramirez; J. Wang; J. Redemann; B. Schmid; M. Box; B. N. Holben

2004-01-01

391

The strongest desert dust intrusion mixed with smoke over the Iberian Peninsula registered with Sun photometry  

Microsoft Academic Search

We present the analysis of the strongest North African desert dust (DD) intrusion that occurred over the Iberian Peninsula (IP) during the last decade, as registered by modern remote sensing techniques like Sun photometry. This event took place from 22 July to 3 August 2004. The most relevant features of this exceptional event, originated over the Saharan desert, were its

V. E. Cachorro; C. Toledano; N. Prats; M. Sorribas; S. Mogo; A. Berjón; B. Torres; R. Rodrigo; J. de la Rosa; A. M. De Frutos

2008-01-01

392

Photometry and Spectrophotometry of the New Variable Star IRAS 20192+3025  

NASA Astrophysics Data System (ADS)

We present CCD V and Ic band photometry and spectrophotometry of the object IRAS 20192+3025. The results of this study indicate the object to be a red giant of spectral type M4-6 with periodic variations in the light curve at 20.9 and 40.6 days. The resulting variability type is SRB.

West, J. D.; Alexander, D. R.

2001-11-01

393

Near-infrared photometry of carbon stars in the Sagittarius dwarf irregular galaxy and DDO 210  

NASA Astrophysics Data System (ADS)

Aims:We investigate the intermediate-age asymptotic giant branch stellar population of two Local Group dwarf irregular galaxies to characterize their carbon star population in near-infrared (IR). Methods: Our work is based on near-IR photometry complemented with optical ground based and Hubble Space Telescope (HST) photometry. Near-IR photometry is based on our and archival J and K_s-band images from SOFI near-IR array of the ESO New Technology Telescope (NTT). Optical photometry for DDO 210 is from the EMMI optical imager of ESO NTT, while the SagDIG optical data come from Momany et al. (2005, A&A, 439, 111). Results: We show that near-IR photometry is a very powerful tool for carbon star detection. We recovered two out of three previously-known carbon stars in DDO 210 and discovered six additional objects in this galaxy which have optical and near-IR colors consistent with carbon giants. This brings the total number of bona fide C-star candidates in DDO 210 to nine. However, to confirm the nature of these objects additional higher spatial resolution imaging or spectroscopic data are necessary. We detected a large population of C-star candidates in SagDIG, 18 of which were previously identified in Demers & Battinelli (2002, AJ, 123, 238) and Cook (1987, Ph.D. Thesis), and six new bona fide carbon stars. We present their optical and near-IR colors and use their luminosity function to put constraints on the star formation history (SFH) in this dwarf irregular galaxy. Based on data collected at the European Southern Observatory, La Silla, Chile, Proposal No. 71.D-0560, and archived ESO data from the Proposal No. 61.E-0273. Appendix A is only available in electronic form at http://www.aanda.org

Gullieuszik, M.; Rejkuba, M.; Cioni, M. R.; Habing, H. J.; Held, E. V.

2007-11-01

394

Deep Multi-Color Surface Photometry of an Edge-on Spiral Galaxy Halo  

NASA Astrophysics Data System (ADS)

Using telescopes at CTIO and at the South Pole, we have obtained very deep VR&K band images of the late type edge-on spiral galaxy ESO 240-G11. We use these data, and stellar population synthesis models, to discuss halo, bulge, and disk stellar populations in the context of recent N-body simulations.

Rauscher, B. J.; Barnaby, D.

2000-12-01

395

Optical multiband surface photometry of a sample of Seyfert galaxies: III. Global, isophotal, and bar parameters  

NASA Astrophysics Data System (ADS)

This paper is third in a series, studying the optical properties of a sample of Seyfert galaxies. Here we present a homogeneous set of global (ellipticity, position angle, inclination, and total magnitude) and isophotal (semi-major axis and colour indices at 24 V mag arcsec-2) parameters of the galaxy sample. We find the following median corrected isophotal colour indices: {(B-I_C)24(0)=1.9} mag arcsec-2 and {(V-I_C)24(0)=1.1} mag arcsec-2. A set of bar parameters (ellipticity, position angle, semi-major axis corresponding to the ellipticity maximum in the bar region, and length) are also reported; deprojection has been applied to the bar ellipticity, length, and relative length in terms of galaxy isophotal semi-major axis. Regarding bar length estimation, we use a method, based on the relation between the behaviour of the profiles and orbit analysis. The so estimated bar length tightly correlates with the semi-major axis, corresponding to the ellipticity maximum with a median ratio of the former to the latter of 1.22. The median of the deprojected bar ellipticity, length, and relative length are 0.39, 5.44 kpc, and 0.44, respectively. There is a correlation between the deprojected bar length and the corrected isophotal semi-major axis at 24 V mag arcsec-2. Three of the 17 large-scale bars appear strong, based on the deprojected bar ellipticity as a first-order approximation of bar strength. The deprojected relative bar length does not appear to correlate with the bar ellipticity. Based on observations obtained with the 2-m telescope of the Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences.

Slavcheva-Mihova, L.; Mihov, B.

2011-02-01

396

Some problems in calibrating UBV photometry for effective temperature and surface gravity  

Microsoft Academic Search

The spectrophotometry of 54 A\\/B stars and of the RR Lyrae variable SU Dra was reduced to the recent recalibration of Vega. By integrating the reduced spectrophotometric results the colors of these stars were calculated. A plot of the computed versus directly observed color indices forms a 45 deg line if b-y is considered. This suggests that the spectrometry, the

S. Barcza; S. Szilagyi

1981-01-01

397

The envelope of IRC +10216 reflecting the galactic light. UBV surface brightness photometry and interpretation  

NASA Astrophysics Data System (ADS)

We present and analyse new optical images of the dust envelope surrounding the high mass-loss carbon star IRC +10216. This envelope is seen due to external illumination by galactic light. Intensity profiles and colors of the nebula were obtained in the UBV bandpasses. The data are compared with the results of a radiative transfer model calculating multiple scattering of interstellar field photons by dust grains with a single radius. The data show that the observed radial shape of the nebula, especially its half maximum radius, does not depend on wavelength (within experimental errors), suggesting that grains scatter in the grey regime, and this is further supported by the plateau colors being close to those of the ISRF as given by Mattila (\\cite{mattila80a}). A grain radius of 0.16 mu m with envelope parameters as proposed by Groenewegen (\\cite{groenewegen97}) can reproduce this achromatism of shape and color characteristics. However, there remain substantial discrepancies between model and observations concerning the absolute intensity of the nebula and its radial shape. Some of these discrepancies disappear if one adopts a small grain size ( ~ 0.05 mu m), or if one assumes a lower dust mass loss rate for the outer layers (theta >=20'', corresponding to 1000 years ago). Within the framework of our simple model, we cannot determine a ``dominant'' grain size. Future more sophisticated models will have to take into account grain size distribution, and also explore complicated issues like the effects of grain porosity and/or asphericity on scattering, the influence of the envelope small-scale structure on the radiative transfer, and the possibility of a field anisotropy. For the same reasons, it is not presently feasible to establish with confidence whether the interstellar radiation field in the visible is significantly different in strength at the location of IRC +10216 compared to the usually adopted one in the solar neighbourhood. Based on observations made with the Antu 8-m VLT (ESO; program 63I-0177A), with the Canada France Hawaii 3.6-m Telescope (CNRS, NRC, UH) and the 1.20-m telescope of Haute-Provence Observatory (CNRS).

Mauron, N.; de Laverny, P.; Lopez, B.

2003-04-01

398

Affective Wearables  

Microsoft Academic Search

An "affective wearable" is a wearable systemequipped with sensors and tools which enablesrecognition of its wearer's affective patterns. Affectivepatterns include expressions of emotionsuch as a joyful smile, an angry gesture, astrained voice or a change in autonomic nervoussystem activity such as accelerated heart rateor increasing skin conductivity. This paper describesnew applications of affective wearables,and presents a prototype which gathers physiologicalsignals

Rosalind W. Picard; Jennifer Healey

1997-01-01

399

Affective Objects  

Microsoft Academic Search

This paper will attempt t o d efine a new area of research: affective c ommunication through the use of affective objects. An affective object may be defined as any physical object which has the ability to sense emotional data from a person, map that information to an abstract form of expression and communicate that information expressively, either back to

Jocelyn Scheirer; Rosalind W. Picard

400

The imprints of mass segregation on the integrated photometry of star clusters  

NASA Astrophysics Data System (ADS)

The development of a radial dependence of the stellar mass function (MF) within a cluster with time (called "mass segregation") is a well-established result both from observations and from simulations. However, as the low-mass stars moved to the outer parts of the cluster are easiest stripped off by tidal effects, mass segregation also has an impact on the integrated cluster photometry. Therefore, we calculated the broad-band photometric evolution of unresolved star clusters, including the loss of low-mass stars due to mass segregation. The MF of a cluster evolves due to three effects: 1. the evolution of massive stars 2. early tidal effects reduce the MF independently of the stellar mass 3. after mass segregation has completed, tidal effects preferentially remove the lowest-mass stars from the cluster. 4. Results: • During the first ~40% of the lifetime of a cluster the cluster simply gets fainter due to the general loss of stars by tidal effects. • Between ~40 and ~80% of its lifetime the cluster gets bluer due to the loss of low-mass stars. This will result in an underestimate of the age of clusters from standard cluster evolution models (0.15-0.5 dex) • After ~80% of the total lifetime of a cluster it will rapidly get redder. This is because stars at the low-mass end of the main sequence, which are preferentially lost, are bluer than the AGB stars dominating the light at long wavelengths, resulting in an age overestimate. • Clusters with mass segregation and the preferential loss of low-mass stars evolve along almost the same tracks in colour-colour diagrams as clusters without mass segregation. Therefore it will be difficult to distinguish this effect from that due to the cluster age for unresolved clusters, unless the total lifetime of the clusters can be estimated. • The changes in the colour evolution of unresolved clusters due to the preferential loss of low-mass stars will affect the determination of the SFHs of galaxies and might explain the presence of old clusters in NGC 4365, photometrically disguised as intermediate-age clusters.

Anders, P.; Lamers, H. J. G. L. M.; de Grijs, R.

2006-08-01

401

CFHTLenS: improving the quality of photometric redshifts with precision photometry  

NASA Astrophysics Data System (ADS)

Here we present the results of various approaches to measure accurate colours and photometric redshifts (photo-z) from wide-field imaging data. We use data from the Canada-France-Hawaii Telescope Legacy Survey which have been re-processed by the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) team in order to carry out a number of weak gravitational lensing studies. An emphasis is put on the correction of systematic effects in the photo-z arising from the different point spread functions (PSFs) in the five optical bands. Different ways of correcting these effects are discussed and the resulting photo-z accuracies are quantified by comparing the photo-z to large spectroscopic redshift (spec-z) data sets. Careful homogenization of the PSF between bands leads to increased overall accuracy of photo-z. The gain is particularly pronounced at fainter magnitudes where galaxies are smaller and flux measurements are affected more by PSF effects. We discuss ways of defining more secure subsamples of galaxies as well as a shape- and colour-based star-galaxy separation method, and we present redshift distributions for different magnitude limits. We also study possible re-calibrations of the photometric zero-points (ZPs) with the help of galaxies with known spec-z. We find that if PSF effects are properly taken into account, a re-calibration of the ZPs becomes much less important suggesting that previous such re-calibrations described in the literature could in fact be mostly corrections for PSF effects rather than corrections for real inaccuracies in the ZPs. The implications of this finding for future surveys like the Kilo Degree Survey (KiDS), Dark Energy Survey (DES), Large Synoptic Survey Telescope or Euclid are mixed. On the one hand, ZP re-calibrations with spec-z values might not be as accurate as previously thought. On the other hand, careful PSF homogenization might provide a way out and yield accurate, homogeneous photometry without the need for full spectroscopic coverage. This is the first paper in a series describing the technical aspects of CFHTLenS.

Hildebrandt, H.; Erben, T.; Kuijken, K.; van Waerbeke, L.; Heymans, C.; Coupon, J.; Benjamin, J.; Bonnett, C.; Fu, L.; Hoekstra, H.; Kitching, T. D.; Mellier, Y.; Miller, L.; Velander, M.; Hudson, M. J.; Rowe, B. T. P.; Schrabback, T.; Semboloni, E.; Benítez, N.

2012-04-01

402

NEAR Infrared Spectrometer Photometry of Asteroid 433 Eros  

Microsoft Academic Search

A few hours before going into orbit on February 14, 2000, the NEAR spacecraft flew through the zero phase point between the Sun and Eros, obtaining spectra of the surface from 0.8 to 2.5 microns, at spatial resolutions of 5.5 to 2.5 km\\/spectrum, and at phase angles ranging from 1 to 37 degrees. Several weeks later during the orbital phase

B. E. Clark; P. Helfenstein; J. F. Bell III; J. Veverka; N. I. Izenberg; D. Domingue; D. Wellnitz; L. McFadden

2000-01-01

403

VI HST photometry of VV124 = UGC4879 (Bellazzini+, 2011)  

NASA Astrophysics Data System (ADS)

Magnitudes (in the ACS-WFC VEGAMAG system), positions and crowding parameter (CRO) for 69795 stars in the considered HST ACS-WFC field (dwarf galaxy VV124). In the paper the analysis is limited to the subsample of 44894 stars having CRO<0.3. However we relaxed this limit to CRO<1.0 to study the two star clusters, that are affected by extra-crowding. Hence, to allow the full reproducibility of our analysis, all stars with CRO<1.0 have been included in the present catalog. See the paper for the other selections applied on the original photometric sample. (1 data file).

Bellazzini, M.; Perina, S.; Galleti, S.; Oosterloo, T.

2011-07-01

404

Aspects of Geneva photometry. Part 4 - Working with dusty data  

NASA Astrophysics Data System (ADS)

In this fourth part of the article, we look at the manner in which interstellar extinction complicates the photometric calibration process even though the parameters used here are essentially reddening-free. This is particularly true for the fundamental observational estimate of stellar intrinsic luminosity habitually expressed as the absolute magnitude Mv. The primary stellar distance scale is based on trigonometrically derived distances (parallaxes) which are not affected by extinction. But, in the presence of interstellar reddening, one must be able to accurately compensate for that effect to fully exploit the distance data.

Cramer, Noel

2005-04-01

405

Strömgren and Hbeta photometry of O and B type stars in star-forming regions. I. Canis Major - Puppis - Vela  

Microsoft Academic Search

Strömgren and Hbeta photometry of OB-stars generally brighter than 9.5 mag in the Canis Major - Puppis - Vela region of Milky Way is reported. The observations are based on the Milky Way luminous-star (LS) identifications and are designed to create a complete, magnitude-limited sample of LS for this field. We present new uvby photometry for 127 LS and Hbeta

N. T. Kaltcheva; E. H. Olsen

1999-01-01

406

Strömgren-H? Photometry of the Galactic Open Cluster M11  

NASA Astrophysics Data System (ADS)

We present uvby? CCD photometry of the central region of the rich Galactic open cluster M11. Our study utilizes photometric data obtained with the 0.9-m WIYN telescope at the Kitt Peak National Observatory during two observing runs in 2007 and 2008. We match stars by position to identified stars in the WEBDA catalog and we compare our V and b-y observations to two previously-published data sets of V and B-V observations. From our photometry we identify nearly 250 stars earlier than spectral type A0 and we use them to derive a metallicity-independent average color excess and distance for the cluster. Our magnitude limit of V=17 allows us to reach late G spectral type and obtain accurate fits to the ZAMS in order to estimate the age of the cluster. Acknowledgements: this work was supported by NSF grants AST-0708950 and AST-1135760.

Beaver, John; Briley, M. M.; Kaltcheva, N.; Conger, C.; Piehl, D.

2013-01-01

407

MIPS Photometry of the HD 141569 Triple System: Resolving a Puzzle and Searching for Disks  

NASA Astrophysics Data System (ADS)

HD 141569A sports a dusty disk in the throes of transition from primordial proto-planetary disk to Beta Pictoris-like debris disk. As such stars are rare, it has been much studied and modeled. It also happens to be part of a 5 Myr old triple system with two M-type weak-line T Tauri star companions. Despite many studies over the last five years, the amount of mid-infrared emission from the disk around HD 141569A is unclear. Published ground-based 12 and 18 micron photometry disagree with each other and with IRAS results. I propose MIPS photometry of HD 141569 to help resolve the confusion over the flux density from this star and to look for small amounts of dust around the companions at 24 micron.

Weinberger, Alycia

2004-09-01

408

(RI)c photometry of variables in M31 (Joshi+, 2003)  

NASA Astrophysics Data System (ADS)

We present Cousins R and I band photometry of variable stars in a ~13'x13' region in the disk of M31 galaxy, obtained during 141 nights. Of the 26 Cepheid variables present in the region, two are newly discovered, 11 are classified as Cepheids for the first time and 13 are confirmed as Cepheids. The extensive photometry of these Cepheids enabled us to determine precise phase and amplitude of pulsation which ranges from 0.11 to 0.48mag in R band. The period of variability ranges from ~7.5 to 56 days. The period-luminosity diagram is used to derive a distance modulus of 24.49+/-0.11mag for M31 galaxy. We also report variability in 333 other stars, of them, 115 stars appear to be long period variables, 2 suspected eclipsing binaries and remaining 216 are irregular variables. (4 data files).

Joshi, Y. C.; Pandey, A. K.; Narashimha, D.; Sagar, R.; Giraud-Heraud, Y.

2003-03-01

409

The Photometry of Cataclysmic Variable V1159 Ori and BZ UMa  

NASA Astrophysics Data System (ADS)

Photometry of the cataclysmic variables V1159 Ori and BZ UMa are conducted with the 1m RCC optical telescope in Yunnan Astronomical Observatory from Feb. 24th to 25th, 2008. The light curves of V1159 Ori denote superhumps during the fading period of a normal outburst. Previous observations revealed superhumps in ER UMa during normal outbursts, convincing that it is universal in ER UMa class. This photometry helps to assure superhumps' presence in ordinary outbursts of ER UMa class. As to the controversial BZ UMa, whose orbital period is below the period gap of SU Uma, no apparent observable superhumps are detected in either previous observations or that of this time. Therefore, it is more likely to side with U Gem class or WZ Sge class, with the latter of more likelihood.

Jiang, L. L.; Jiang, F. Z.; Li, Z. Y.; Zhao, Y. H.; Gu, Q. S.

2010-01-01

410

First Results from Photometry and Astrometry of Selected Minor Planets at TÜBITAK National Observatory  

NASA Astrophysics Data System (ADS)

Large size of 1.5m Russian-Turkish Telescope (RTT150) (Aslan 2001) for the tasks of astrometry and photometry of minor planets (MPs) together with astro-climatic conditions of the TÜBITAK National Observatory (TUG) in Turkey, allows us to get high-quality data. We observed the Apollo asteroid 2002 NY_{40} with the RTT150 Telescope in BVRc-bands between 2002 July 30 and 2002 August 14. The difference detected in bv color between the maximum and minimum of the phased light curve is attributed to a possible difference in albedo of different parts of the asteroid body. During the period of 2004-2005, we also observed 11 pre-calculated events of asteroid occultation and no positive events detected in all cases. The reasons of the negative results are discussed. Photometry of MPs according to USNO-B1 stars is presented.

Uluç, K.; Khamitov, I.; Özi?ik, T.; Bikmaev, I.; Aslan, Z.; Tunca, Z.

2007-05-01

411

Photometric study of selected cataclysmic variables II. Time-series photometry of nine systems.  

NASA Astrophysics Data System (ADS)

We present time-series photometry of nine cataclysmic variables: EI UMa, V844 Her, V751 Cyg, V516 Cyg, GZ Cnc, TY Psc, V1315 Aql, ASAS J002511+1217.2, V1315 Aql and LN UMa. The observations were conducted at various observatories, covering 170 hours and comprising 7,850 data points in total. For the majority of targets we confirm previously reported periodicities and for some of them we give, for the first time through photometry, their underlying spectroscopic orbital period. For those dwarf-nova systems which we observed during both quiescence and outburst, the increase in brightness was accompanied by a decrease in the level of flickering. For the eclipsing system V1315 Aql we have covered 9 eclipses, and obtained a refined orbital ephemeris. We find that, during this long baseline of observations, no change in the orbital period of this system has occurred. V1315 Aql also shows eclipses of variable depth.

Papadaki, C.; Boffin, H. M. J.; Stanishev, V.; Boumis, P.; Akras, S.; Sterken, C.

2009-05-01

412

Spectroscopic parallaxes of MAP region stars from UBVRI, DDO, and uvbyH-beta photometry  

NASA Astrophysics Data System (ADS)

This paper presents the results of spectral type and luminosity classification of reference stars in the Allegheny Observatory MAP parallax program, using broadband and intermediate-band photometry. In addition to the use of UBVRI and DDO photometric systems, the uvbyH-beta photometric system was included for classification of blue (B - V less than 0.6) reference stars. The stellar classifications made from the photometry are used to determine spectroscopic parallaxes. The spectroscopic parallaxes are used in turn to adjust the relative parallaxes measured with the MAP to absolute parallaxes. A new method for dereddening stars using more than one photometric system is presented. In the process of dereddening, visual extinctions, spectral types, and luminosity classes are determined, as well as a measure of the goodness of fit. The measure of goodness of fit quantifies confidence in the stellar classifications. It is found that the spectral types are reliable to within 2.5 spectral subclasses.

Persinger, Tim; Castelaz, Michael W.

1990-11-01

413

Johnson BV and Cousins RI photometry of some cool giant stars  

NASA Astrophysics Data System (ADS)

We examine Johnson BV and Cousins RI photometry of the cool giant stars HR 1105, HD 35155, HR 4088, TU CVn, IT Vir, and HR 7442, that the first author obtained with the Four College Automated Photoelectric Telescope. The new data for HR 1105 show that its variability is more complex than previously thought Except a 0.3 phase gap in the photometry of HD 35155, the amplitude of variability is fairly constant. For HR 4088, except for one season, we did not find any periods shorter than 100 days. For the barium star IT Vir assuming the orbital period is the photometric period, the light curves consist of two similar subparts each one-half of the orbital period long. But there are problems with concluding that this star is an ellipsoidal variable. For HR 7442, more data is needed to derive an accurate period. A few observations are also presented of HR 1556, HR 363, HD 58521, and HD 49368.

Adelman, S. J.; Colegrove, B. S.; Woodrow, S. L.

414

Spectrophotometric Libraries, Revised Photonic Passbands, and Zero Points for UBVRI, Hipparcos, and Tycho Photometry  

NASA Astrophysics Data System (ADS)

We have calculated improved photonic passbands for the UBVRI, Hipparcos Hp, Tycho BT and VT standard systems using the extensive spectrophotometric libraries of NGSL and MILES. Using the Hp passband, we adjusted the absolute flux levels of stars in the spectrophotometric libraries so that their synthetic Hp magnitudes matched the precise Hipparcos Catalogue value. Synthetic photometry based on the renormalized fluxes was compared with the standard UBVRI, BT and VT magnitudes, and revised synthetic zero points were determined. The Hipparcos and Tycho photometry system zero points were also compared with the V-magnitude zero points of the SAAO UBVRI system, the homogenized UBV system, and the Walraven VB system. The confusion in the literature concerning broadband magnitudes, fluxes, passbands, and the choice of appropriate mean wavelengths is detailed and discussed in the Appendix.

Bessell, Michael; Murphy, Simon

2012-02-01