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1

Photometry of icy satellite surfaces  

Microsoft Academic Search

Detailed photometric analyses of icy satellite surfaces are used to determine physical regolith properties indicative of exogenic and endogenic geologic processes. The Hapke (1986) photometric equation relates the average single scattering albedo, regolith compaction, mean topographic slope angle, and average directional scattering behavior of a particulate surface to the reflectance observed at specific viewing geometries. The Hapke equation was applied

Anne Jacqueline Verbiscer

1991-01-01

2

Hubble Deep Field surface photometry (Fasano+ 1998)  

NASA Astrophysics Data System (ADS)

The detailed surface photometry of a sample of early-type galaxies in the Hubble Deep Field is presented as part of a long-term project aimed to settle strong observational constraints to the theories modelling the evolution of elliptical galaxies from the early stages. The sample has been extracted, in the V606 band, from the database provided by the ESO-STECF-HDF Group (Couch, 1996, ). The selection criteria involve the total magnitude, the number of pixels detected above the background level and an automatic star/galaxy classifier. Moreover, form visual inspection of the frames, we excluded the galaxies showing unambiguous late-type morphology. The analysis of the luminosity and geometrical profiles, carried out on the 162 candidates obeying our selection criteria, resulted in a list of 99 'bona fide' early-type galaxies, for which accurate total magnitudes and effective radii were computed on the basis of the equivalent luminosity profiles. The comparison with the magnitudes given by Williams et al. (1996, Cat. ) indicates that the automated photometry tends to underestimate the total luminosity of the ellipticals. The luminosity profiles of most of galaxies in our sample follow fairly well the de~Vaucouleurs law ('Normal' profiles). However, a relevant fraction of galaxies, even following the r1/4 law in the main body light distribution, exhibit in the inner region a flattening of the luminosity profile not attributable to the PSF (`Flat' profiles) or, in some cases, a complex (multi-nucleus) structure (`Merger' profiles). A statistically significant correlation is found between the shapes of the luminosity profiles and the ellipticity distribution. In particular, the average ellipticity of galaxies belonging to the `Flat' and `Merger' classes is significantly higher than that of the `Normal' galaxies. Finally, even taken into account the relevant uncertainty of the outer position angle profiles, the amount of isophotal twisting of HDF ellipticals turns out to be significantly larger with respect to that of the local samples. (2 data files).

Fasano, G.; Filippi, M.; Bertola, F.

1997-11-01

3

Surface photometry of comet P/Encke  

NASA Astrophysics Data System (ADS)

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

Djorgovski, S.; Spinrad, H.

1985-05-01

4

Automated surface photometry for the Coma Cluster galaxies: The catalog  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

5

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

Microsoft Academic Search

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

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

1990-01-01

6

High-resolution surface photometry of elliptical galaxies  

NASA Technical Reports Server (NTRS)

High-resolution CCD surface photometry profiles have been obtained for a sample of 42 nearby elliptical and SO galaxies as a first step in a program to investigate their central structure and core properties. A comparison of the present profiles to those of other observers shows that the accuracy of the central surface brightnesses is to better than 0.02 mag rms. Central resolution is limited by the atmospheric seeing PSF which is measured for each profile. A hybrid Fourier deconvolution procedure has been developed to correct the surface photometry for seeing in a model-independent way. Tests of the procedure on simulated galaxy images show that intrinsic core radii equal to the seeing FWHM or larger can be recovered from the observations. Application of the deconvolution procedure to the observed galaxies yields surface photometry profiles of slightly sub-arc second resolution.

Lauer, T. R.

1985-01-01

7

CCD photometry of Abell clusters. II - Surface photometry of 249 cluster galaxies  

NASA Technical Reports Server (NTRS)

The luminosity of the brightest cluster galaxies remains the best standard candle for observational cosmology. Studies of over 250 relatively nearby clusters show that the luminosity of these objects within an aperture of constant metric diameter has a dispersion of only 0.35 mag. The observations considered by Schneider et al. (1983) were acquired to measure the aperture luminosities of the brightest cluster galaxies. However, the data base, because of its high signal-to-noise ratio and large spatial coverage, allows several other investigations to be performed. In the present investigation, surface photometry of the brightness three galaxies within approximately 250 kpc of the cluster center is presented, taking into account the cores of 83 Abell clusters. The relevance of the photometry to cosmological studies is also discussed. It is found that dynamical friction does play an extremely important role in determining properties of brightest cluster galaxies and cluster morphology.

Schneider, D. P.; Hoessel, J. G.; Schneider, D. P.

1983-01-01

8

Photometry of the lunar surface during lunar eclipses  

Microsoft Academic Search

The photometric observations of the lunar surface during lunar eclipses were carried out on four nights between 1972 to 1978, using the 91 cm reflector of the Dodaira Station of the Tokyo Astronomical Observatory. The photometry was performed in B-, V-, and R-colours, and arranged in accordance with the angular distance from the centre of the Earth's shadow. The results

Naosuke Sekiguchi

1980-01-01

9

Adaptive Filter Applications in Surface Photometry of Galaxies  

Microsoft Academic Search

We consider the smoothing application of the adaptive filter, juxtaposed to the other most commonly used filters, in the surface photometry of galaxies. We point out the adaptive filter advantages and illustrate them with the azimuthally shrunk luminosity profiles of the Seyfert galaxy NGC 5548.

L. S. Slavcheva-Mihova; B. M. Mihov; G. T. Petrov

2006-01-01

10

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

11

Surface photometry of a sample of elliptical and S0 galaxies  

SciTech Connect

The results are reported of surface photometry of 38 early-type galaxies, located mainly in the Fornax Cluster. Detailed comparisons with previously published work are given along with internal and external error estimates for all quantities, and some serious systematic discrepancies in the older aperture photometry of some of the galaxies in the present sample are pointed out. 15 refs.

De carvalho, R.R.; Da costa, L.N.; Djorgovski, S. (Observatorio Nacional do Brasil, Sao Cristovao (Brazil) California Institute of Technology, Pasadena (United States))

1991-08-01

12

Surface photometry in 7 nearby clusters (Fasano+, 2002)  

NASA Astrophysics Data System (ADS)

This is the first paper of a series investigating the scaling relations of early-type galaxies in clusters. Here we illustrate the multi-band imagery and the image reduction and calibration procedures relative to the whole sample of 22 clusters at 0.05<~z<~0.25. We also present detailed surface photometry of 312 early-type galaxies in 7 clusters (A1069, A119, A1983, A2151, A2670, A3125 and DC2103) in the first redshift bin, z=0.025-0.075. We give for each galaxy the complete set of luminosity and geometrical profiles, and a number of global, photometric and morphological parameters. They have been evaluated taking into account the effects of seeing. Internal consistency checks and comparisons with data in the literature confirm the quality of our analysis. These data, together with the spectroscopic ones presented in the second paper of the series, will provide the local calibration of the scaling relations. (2 data files).

Fasano, G.; Bettoni, D.; D'Onofrio, M.; Kjfrgaard, P.; Moles, M.

2002-05-01

13

Photographic surface photometry of the Milky Way. III - Photometry of the central area of the Galaxy in the ultraviolet  

NASA Astrophysics Data System (ADS)

6 photographic plates, taken at La Silla, Chile, with the spherical mirror super-wide-angle camera of the Astronomisches Institut der Ruhr Universität Bochum (see paper I: Schmidt-Kaler, Th. et al., 1982) were measured to study the surface brightness distribution in the area around the centre of the Milky Way, between galactic longitudes 297° and 27°, and latitudes - 30° to + 30°, with an angular resolution of 0.°3 × 0.°3 (Fig. 5). In section 2 the plate material and details of the reductions are presented, so far as not already given in paper I. During the photometric scanning of the plates all stars brighter than a limiting magnitude mlim were marked by hand, and the corresponding data points were replaced by an average from neighbouring points (section 3). Defined at the level of 50% elimination, mlim ? 8.m0 (in U). Figure 4 shows the effect of various methods of eliminating bright stars. The errors of the surface photometry are discussed in section 4. The internal mean error of the intensity of one data point, as determined from the scatter from the 6 plates, is ± 9.4%. This error is split into an additive component ± 8 S10U (S10 = intensity of a star of 10m), mostly due to the contributions of airglow and scattered light, and a multiplicative component of ± 7.5%, mostly due to the uncertainty of the photographic characteristic curve. Possible systematic errors are estimated and upper limits for these are given in table II. Section 5 presents the results of the photometry. For the sake of clear representation in the isophote map (Fig 5) data with intermediate intensities 110 < Igal ? 250 S10U were smoothed over 0.°9 × 0.°9, data with Igal ? 110 S10U were smoothed over 1.°2 × 1.°2. The mean error of the isophotes is about ± 6%. We then compare our photometry with existing ultraviolet surface photometries. Apart from the area l = 320° to 330°, b = -25° to -20° where our intensities are probably vitiated by some remaining airglow influence, there is generally very good agreement with the results of Seidensticker, Schinidt-Kaler and Schlosser (= paper II), their values being smaller by a statistically insignificant additive difference of -14(± 15) S10U. The comparison (Fig 6) with the photoelectric surface photometry of Pfleiderer and Mayer (1971) shows a negligible additive difference of -8 (± 12) S10U, but a large scale difference of 24(± 9)%, the Bochum values being larger. The comparison with the measurements of Leinert and Richter (1981), obtained by the satellite Helios, shows very good agreement in the run of the intensities (Fig. 7). Computation of a point by point correlation reveals their values being smaller by an additive difference of -5 (± 2) S10U and a scale difference of 17(± 2)%. As obvious from figure 7 the main difference in the two photometry results from the finer structures in our data, due to different resolution and different completeness in eliminating background stars. Thus we constructed a lower envelope to our data. This reveals an additive difference of 0 (± 0.3) S10U and a scale difference of 2.4 (± 9)% in the same sense as above. In the last paragraph we discuss the structure of the Milky Way central region in U, in particular those spiral filaments which appear inclined to the galactic equator (shingles, corrugations). The three shingles discovered by Schmidt-Kaler and Schlosser (1973) in the next-inner spiral arm-I and an additional feature appear if the data-field of the UV photometry is spatially differentiated (Fig. 8).

Proell, H. J.; Schmidt-Kaler, T.; Schlosser, W.

1983-01-01

14

Europa: Color, Photometry, and the Appearance of Surface Features  

NASA Astrophysics Data System (ADS)

The new Europa images currently being acquired by the Galileo spacecraft, in addition to the Voyager dataset, provide an excellent starting point for understanding the properties of Europa's icy surface. Classification of spectral units on the surface of Europa is important for relative age dating of surface features [1,2], but first we must normalize variations due to photometric angles and global exogenic modification pattern(s). Accurate cartography is also important to compare tectonic features with global-scale stress patterns. We report continuing progress in the production of global-scale merged mosaics of Europa, combining Voyager and Galileo data taken in a variety of colors, resolutions, and phase angles [3]. Due to the limited nature of this dataset, understanding how the appearance of surface features changes due to various perturbations of these parameters is necessary for compositional analysis, geologic mapping and classification of features, and relative age dating. Overlapping datasets can also be merged to produce images which retain characteristics of each individual observation. We will show examples in which low-resolution color, medium-resolution albedo, and high-resolution topography observations have been combined to produce a single image which reveals both spectral information and relative ages of surface features. As described by Geissler et al [1], distinct spectral units of the surface may represent different exposure ages of surface material, which could have important implications for the geologic history of Europa, and by extension the other Galilean satellites. It is our hope that a careful analysis of the merged Galileo-Voyager dataset for Europa will result in an improved understanding of this problem. [1] Geissler, P.E., et al, LPSC XXVIII, 1997; [2] Clark, B.E., et al, LPSC XXVIII, 1997; [3] Phillips, C.B., et al, LPSC XXVIII, 1997

Phillips, C. B.; McEwen, A. S.; Geissler, P. E.; Clark, B. E.; Sullivan, R.; Greeley, R.; Galileo SSI Team

1997-07-01

15

Multicolour surface photometry of Seyfert galaxies: first results  

Microsoft Academic Search

One- or two-dimensional decomposition of surface brightness distribution to its individual components is a technique widely used in studying Seyfert galaxies. Almost all decompositions of Seyfert galaxies light distribution made by different groups are based on the following analytical models for the separate components: single\\/double Gaussian for the nucleus, de Vaucouleurs law for the bulge and exponential law for the

Luba S. Slavcheva-Mihova; Georgy T. Petrov; Boyko M. Mihov

2005-01-01

16

Surface properties and photometry of the Uranian satellites  

NASA Astrophysics Data System (ADS)

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

Buratti, B.; Wong, F.; Mosher, J.

1990-03-01

17

Voyager photometry of surface features on Ganymede and Callisto  

NASA Technical Reports Server (NTRS)

Photometric properties of selected surface features on Ganymede and Callisto are studied, using Voyager images over phase angles from 10 to 124 deg, taken with a clear filter (effective wavelength of approximately 0.5 microns). Normal reflectances on Ganymede average 0.35 for the cratered terrain, and 0.44 for the grooved terrain; the ubiquitous cratered terrain on Callisto is 0.18. The photometric properties of these regions are described by a simple scattering function, where the function of the phase angle is qualitatively similar to that of the moon, i.e., concave upward. By contrast, bright craters on both satellites have functions of the phase angle which are concave downward. The scattering function is not Lambertian, and may be due to an admixture of a small amount of dark, opaque silicate grains with the frost deposits. The brightest craters on Callisto have reflectances which are 10% lower than the brightest craters on Ganymede, and both have similar scattering laws.

Squyres, S. W.; Veverka, J.

1981-01-01

18

Plate-to-CCD Converter. II Surface Photometry of Early Type Galaxies  

NASA Astrophysics Data System (ADS)

We have developed a new device, Plate-to-CCD Converter(PCC), to conveniently digitize photographic plates in a relatively short time without losing any plate information (Oh et al. 1995). Using this device we have performed surface photometry of 12 early type galaxies. We determined relative orientations and scales to analyze PCC images. We also determined an ellipticity, position angle of the major axis, and a_4 of each galaxy to quantify the distribution of surface brightness. We checked the performance and limitation of this device by comparing the PCC images with those digitized by the ST microdensitometer and those obtained with CCD observations.

Kim, Dong-Woo

1995-12-01

19

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

20

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

NASA Technical Reports Server (NTRS)

Narrowband and UBV photoelectric phase curves of the entire lunar disk and surface photometry of some craters have been interpreted using a newly developed generalized radiative transfer theory for planetary regoliths. The data are well fitted by the theory, yielding information on both macroscopic and microscopic lunar properties. Derived values for the integrated disk geometric albedo are considerably higher than quoted previously, because of the present inclusion of an accurately determined opposition effect. The mean surface roughness, defined as the ratio of the height to the radius of a typical irregularity, is found to be 0.9 + or - 0.1, or somewhat less than the mean value of 1.2 obtained for the asteroids. From the phase curves, wavelength-dependent values of the single scattering albedo and the Henyey-Greenstein asymmetry factor for the average surface particle are derived.

Lumme, K.; Irvine, W. M.

1982-01-01

21

Near Infrared Surface Photometry and Morphology in Virgo Cluster Spiral Galaxy Nuclear Regions.  

NASA Astrophysics Data System (ADS)

This paper was published in the April 1995 Astronomical Journal as: Rauscher, B. J. 1995, "Near Infrared Surface Photometry and Morphology in Virgo Cluster Spiral Galaxy Nuclear Regions." The journal article contains color plates. The reader is strongly encouraged to read the journal article. This paper presents very high spatial resolution (seeing 0.75 arcsec FWHM) K band surface photometry of 15 Virgo cluster spiral galaxy nuclear regions (radii < 1 Kpc). It presents B and I band CCD images of 13 of these galaxies. The goals of the study were: (1) to begin to establish a K band baseline of normal spiral galaxy nuclear regions against which peculiar galaxies may be compared, (2) to provide better constraints on N-body models, and (3) to complement near infrared studies of large scale structure in spiral galaxies with very high resolution imaging of the important nuclear regions. The principal findings are: (1) between 1/4 and 1/3 of these nuclear regions show K band evidence of triaxiality, (2) approximately 1/2 of these galaxies have axisymmetric nuclear regions, and (3) NGC 4321 has a bar that is not detectable in the optical images.

Rauscher, Bernard J.

1995-01-01

22

Surface photometry of binary galaxies. I. A multicolour study of morphologies due to the interaction.  

NASA Astrophysics Data System (ADS)

We present the multicolour (B, V, R) surface photometry of 53 double galaxies. All the pairs belong to the catalogue of Reduzzi & Rampazzo (1995) containing objects selected according to the Karachentsev (1972) criteria. We comment on the morphological, structural and photometric characteristics of pairs and their members. Different classes of interaction induced phenomena, both among early and late-type galaxies, are considered. We found that few early-type galaxies show fine structures. Grand design structure is more frequently detected in binary than in field spirals both for barred and non barred, confirming Elmegreen & Elmegreen's (1982) study. The colour of the tails is consistent with the stripping hypothesis since it is similar to the progenitor galaxy outskirts. Among our objects we have no evident sign of induced star formation in tails. Rings appear on average bluer than the disc as a whole.

Reduzzi, L.; Rampazzo, R.

1996-05-01

23

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

NASA Technical Reports Server (NTRS)

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

Lu, N. Y.

1998-01-01

24

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

25

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

26

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

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

27

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

SciTech Connect

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

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

2012-11-01

28

NGC 4314. I - Visible and short-wavelength infrared surface photometry of the nucleus and bar  

NASA Technical Reports Server (NTRS)

BVI (TI CCD) and JHK (University of Texas IR Camera) surface photometry of NGC 4314, an SB (rs)ap anemic spiral with a nuclear ring containing recent star formation, is presented. The shortwave IR (SWIR) frames reveal a nuclear bar of length 2 arcsec at PA of 0 deg. The nuclear ring and associated dust were detected in all SWIR color indices. A nuclear spiral was detected in the visible and SWIR just exterior to the ring. Extremely low-amplitude spiral-shaped deficits were found in the stellar distribution in the SWIR in this same region. These are attributed to dust, since CO is detectable at or near these locations. Average minor-axis profiles show this galaxy to have a nuclear bulge obeying the de Vaucouleurs r exp 1/4 law for values in the range 2-7 arcsec. The extinction and scattering characteristics of dust near the sites of recent star formation in the nuclear ring are discussed.

Benedict, G. F.; Higdon, J. L.; Tollestrup, E. V.; Hahn, J. M.; Harvey, P. M.

1992-01-01

29

Tracing the Dynamics of Disk Galaxies with Optical and Infrared Surface Photometry: Color Gradients in M99  

Microsoft Academic Search

We present optical and IR surface photometry of M99 (NGC 4254) at g, r_s_, i, J, and K_s_. We also present a K_s_ image of M51 (NGC 5194) for comparison. We use these data to investigate if the presence and strength of spiral structure are wavelength dependent, and hence if they are features in the old stellar disk or in

Rosa A. Gonzalez; James R. Graham

1996-01-01

30

Photometry and Surface Physical Properties of Comet 19P\\/Borrelly  

Microsoft Academic Search

The successful Deep Space 1 flyby of Comet P\\/19 Borrelly offers an unprecedented opportunity to perform disk-resolved photometry and photometric modeling of a comet's nucleus. The flyby occurred at a favorable ground-based apparition, enabling concomitant telescopic observations that provided both the \\

B. J. Buratti; L. A. Soderblom; D. T. Britt; M. D. Hicks; N. Thomas; J. Oberst; R. H. Brown; R. M. Nelson; J. A. Mosher; J. K. Hillier

2001-01-01

31

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

32

Multicolor stellar photometry  

NASA Astrophysics Data System (ADS)

The monograph describes all multicolor photometric systems which were in use for stellar photometry before 1990, particularly the UBV, Strömgren and Vilnius systems. The reviews of common properties of photometric systems, energy distribution in stellar spectra, interstellar and atmospheric extinction, photometric classification methods of stars are also given. The book includes calibrations of spectral MK types in absolute magnitudes, bolometric corrections, effective temperatures, surface gravities, masses and radii. Intrinsic color indices of the UBV, Strömgren, Vilnius and infrared systems are tabulated. The volume of the book is 570 pages. A pdf file of the book is available at: http://www.itpa.lt/MulticolorStellarPhotometry/

Straižys, Vytautas

33

Stellar Populations and the Star Formation Histories of LSB Galaxies: IV Spitzer Surface Photometry of LSB Galaxies  

NASA Astrophysics Data System (ADS)

Surface photometry at 3.6 ?m is presented for 61 low surface brightness (LSB) galaxies (? o <19 3.6 ?m mag arcsecs-2). The sample covers a range of luminosity from -11 to -22 in M 3.6 and size from 1 to 25 kpc. The morphologies in the mid-IR are comparable to those in the optical with 3.6 ?m imaging reaches similar surface brightness depth as ground-based optical imaging. A majority of the resulting surface brightness profiles are single exponential in shape with very few displaying upward or downward breaks. The mean V - 3.6 colour of LSB is 2.3 with a standard deviation of 0.5. Colour-magnitude and two-colour diagrams are well matched to models of constant star formation, where the spread in colour is due to small changes in the star formation rate (SFR) over the last 0.5 Gyrs as also suggested by the specific SFR measured by H?.

Schombert, James M.; McGaugh, Stacy

2014-02-01

34

Fast Photometry  

Microsoft Academic Search

Fast photometry is measuring changes in brightness in the range of several seconds down to a few milliseconds or faster. Increasingly, asteroid and lunar occultation measurements are carried out using camcorders or video cameras. These can be very inexpensive, and allow event timing to about 0.02 sec. GPS timing signals, good to a microsecond or better, can be combined with

J. Menke

2007-01-01

35

Cylinder surface, temperature may affect LPG odorization  

SciTech Connect

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

McWilliams, H.

1988-01-01

36

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

USGS Publications Warehouse

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

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

2006-01-01

37

Lunar Eclipse of June, 15, 2011: Three-color umbra surface photometry  

Microsoft Academic Search

The paper contains the result description of the photometric observations of the Moon surface during the total lunar eclipse of June, 15, 2011 conducted in southern Russia and Ukraine in three narrow spectral bands with effective wavelengths equal to 503, 677, and 867 nm. The photometric maps of umbra are built, the radial dependencies of relative brightness are compared with

Oleg S. Ugolnikov; Igor A. Maslov; Stanislav A. Korotkiy

2011-01-01

38

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

39

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

40

Photometry of Triton 1992-2004: Surface volatile transport and discovery of a remarkable opposition surge  

NASA Astrophysics Data System (ADS)

Triton, the large satellite of Neptune, was imaged by the Voyager 2 spacecraft in 1989 with dark plumes originating in its volatile-rich south polar region. Southern summer solstice, a time when seasonal volatile transport should be at a maximum, occurred in 2001. Ground-based observations of Triton's rotational light curve obtained from Table Mountain Observatory in 2000-2004 reveal volatile transport on its surface. When compared with a static frost model constructed from Voyager images, the light curve shows an increase in total amplitude. An earlier light curve obtained in 1992 from Mauna Kea Observatory is consistent with the static frost model. This movement of volatiles on the surface agrees with recent imaging results from the Hubble Space Telescope (Bauer, J.M., Buratti, B.J., Li, J.-Y., Mosher, J.A., Hicks, M.D., Schmidt, B.E., Goguen, J.D. [2010]. Astrophys. J. 723, L49-L52). The changes in the light curve can be explained by the transport of nitrogen frost on the surface or by the uncovering of bedrock of less volatile methane. We also find that Triton exhibits a large opposition surge at solar phase angles less than 0.1°. This surge cannot be entirely explained by the effects of coherent backscatter.

Buratti, B. J.; Bauer, J. M.; Hicks, M. D.; Hillier, J. K.; Verbiscer, A.; Hammel, H.; Schmidt, B.; Cobb, B.; Herbert, B.; Garsky, M.; Ward, J.; Foust, J.

2011-04-01

41

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

42

Dust-corrected surface photometry of M 31 from Spitzer far-infrared observations  

NASA Astrophysics Data System (ADS)

Aims: We create a model for recovering the intrinsic, absorption-corrected surface brightness distribution of a galaxy and apply the model to the nearby galaxy M 31. Methods: We constructed a galactic model as a superposition of axially symmetric stellar components and a dust disc to analyse the intrinsic absorption effects. Dust column density is assumed to be proportional to the far-infrared flux of the galaxy. Along each line of sight, the observed far-infrared spectral energy distribution was approximated with modified black body functions corresponding to dust components with different temperatures, thereby allowing us to determine the temperatures and relative column densities of the dust components. We applied the model to the nearby galaxy M 31 using the Spitzer Space Telescope far-infrared observations for mapping dust distribution and temperature. A warm and a cold dust component were distinguished. Results: The temperature of the warm dust in M 31 varies between 56 and 60 K and is highest in the spiral arms, while the temperature of the cold component is mostly 15-19 K and rises up to about 25 K at the centre of the galaxy. The intensity-weighted mean temperature of the dust decreases from T ˜ 32 K in the centre to T ˜ 20 K at R˜ 7 kpc and outwards. The scalelength of the dust disc is (a_0)dust ? 1.8~(a_0)stars. We also calculated the intrinsic U, B, V, R, I, and L surface brightness distributions and the spatial luminosity distribution. The intrinsic dust extinction in the V-colour rises from 0.25^m at the centre to 0.4^m-0.5^m at R? 6-13 kpc and decreases smoothly thereafter. The calculated total extinction-corrected luminosity of M 31 is LB = (3.64 ± 0.15) × 1010~L?, corresponding to an absolute luminosity M_B=-20.89 ± 0.04 mag. Of the total B-luminosity, 20% (0.24 mag) is obscured from us by the dust inside M 31. The intrinsic shape of the bulge is slightly prolate in our best-fit model.

Tempel, E.; Tamm, A.; Tenjes, P.

2010-01-01

43

How surface damage removal affects fatigue life  

NASA Technical Reports Server (NTRS)

The effect of the removal of work hardened surface layers from specimens of 2024-T4 aluminum alloy and AISI-4130 steel on their fatigue lives has been investigated. Specimens were fatigued at selected stress levels for a given number of cycles, and the surface layer was removed followed by subsequent fatigue cycling. Results confirm that when a material is subjected to fatigue loading, damage accumulates in the surface layers in the form of work hardening. Removal of the surface layer brings the specimen back to its pre-fatigued condition.

Jeelani, S.; Scott, M. A.

1988-01-01

44

Phytoplankton physiology can affect ocean surface temperatures  

NASA Astrophysics Data System (ADS)

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 models at two locations we show that varying N:Chl a, rather than keeping a fixed mean value (0-150m), leads to lower chlorophyll a in the mixed layer, less light absorption within the mixed layer and cooler sea surface temperatures. At the equator the temperature reduction is 0.15°C throughout the year whereas at 35°N, a temperature difference of about 1°C occurs during the summer. Although demonstrated at only two locations, this effect is likely to occur over large parts of the ocean.

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

45

Sky Survey and Photometry by the GAIA Satellite  

NASA Astrophysics Data System (ADS)

Gaia is designed as a scanning satellite to collect data for high-precision astrometry with standard errors of 10 microarcseconds of positions, parallaxes and annual proper motions for stars brighter than V = 15 mag and sub-milliarcsecond precision for all stars brighter than V = 20 mag. Multicolor photometry will be obtained for these about one billion stars. An overview of the Gaia mission with respect to multicolor photometry of stars is given. The detection of supernovae and solar system objects, and the possibility for surface photometry are discussed. An appendix on Gaia mapping and photometry contains the three sections: samples and patches, precision of aperture photometry, mapping and photometry.

Høg, E.; Fabricius, C.; Knude, J.; Makarov, V. V.

46

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

47

Surface light-induced drift affected by chemical reactions  

Microsoft Academic Search

Surface light-induced drift caused by backscattering from rough surfaces can be strongly affected by surface-enhanced state-specific chemical reactions. Expressions for the drift fluxes of the incident resonant-gas component and of the reaction product are presented. A resulting asymmetry in the spatial distributions of the components in a ssT-shaped enclosure is discussed, as a possible sensitive tool for studying the state

M. A. Vaksman; A. Ben-Reuven

1992-01-01

48

Curvature affects superhydrophobicity on flexible silicone microstructured surfaces  

Microsoft Academic Search

The flexure of microstructured polymers affects hydrophobicity. As curvature becomes more positive, droplets suspended on the tops of asperities are suspended on fewer asperities, resulting in an increase in contact angle and a decrease in slide angle. Critical curvature constraints presented here can be used to design microstructure geometries that maintain the suspension of a droplet when curved surfaces are

A. H. Cannon; W. P. King

2009-01-01

49

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

NASA Astrophysics Data System (ADS)

Evaluation of the forcing of climate by aerosol scattering of shortwave radiation in cloud-free conditions (direct aerosol forcing) requires knowledge of aerosol optical properties on relevant spatial and temporal scales. It is convenient to measure these properties at the surface. However, before these measurements can be used to quantitatively estimate direct climate forcing, it is necessary to determine the extent to which these properties are representative of the entire atmospheric column. In this paper we compare aerosol optical depth (AOD) determined by Sun photometry at the Southern Great Plains (SGP) Atmospheric Radiation Measurement (ARM) site in north central Oklahoma for several cloud-free days with estimates of AOD based on two methods. First, the aerosol extinction measured at the surface (taken as the sum of the aerosol scattering and absorption coefficients at instrumental relative humidity of˜20%) is multiplied by the mixing height determined from temperature profiles from radiosonde measurements. Even under conditions of vigorous midday mixing this approach underestimates AOD by as much as 70% using dry aerosol measurements and by roughly 40% when hygroscopic growth of aerosol under ambient relative humidity is taken into account. This discrepancy is attributed primarily to underestimation of aerosol column extinction, as confirmed by examination of normalized aerosol backscatter profiles obtained from micropulse lidar (MPL), which show substantial contributions of aerosol loading above the atmospheric boundary layer. The second approach uses MPL profiles of normalized aerosol backscatter to estimate the vertical profile of aerosol extinction using surface values. The resulting AOD's are on average 30% less than measured values. This discrepancy is attributed to hygroscopic growth of aerosols in the atmospheric column. The results show that at the SGP site even under conditions of vigorous mixing in the atmospheric boundary layer the aerosol optical depth cannot be estimated with surface measurements of aerosol extinction unless information on the vertical profile of aerosol extinction is taken into account.

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

2000-03-01

50

On the determination of effective temperature and surface gravity of B, A, and F stars using Stromgren UVBY beta photometry  

NASA Astrophysics Data System (ADS)

The determination of stellar temperatures and surface gravities by means of the Stromgren uvby beta photometric system is examined in the region of main sequence stars. We used a sample of stars with independently derived temperatures and gravities. In particular, the calibrations of Moon & Dworetsky (1985), Lester et al. (1986), and Balona (1984) are discussed. We compare our results with Castelli (1991) and present new temperature calibrations for normal, Johnson, and Ap stars. The use of integrated fluxes and especially the infrared flux method for determining stellar temperatures is discussed. Surface gravities of B and A stars, derived by fitting theoretical profiles to the Balmer lines, are used to check the calibrations.

Napiwotzki, R.; Schoenberner, D.; Wenske, V.

1993-02-01

51

Andromeda (M31) Optical and Infrared Disk Survey. I. Insights in Wide-field Near-IR Surface Photometry  

NASA Astrophysics Data System (ADS)

We present wide-field near-infrared J and Ks images of the Andromeda Galaxy (M31) taken with WIRCam at the Canada-France-Hawaii Telescope as part of the Andromeda Optical and Infrared Disk Survey. This data set allows simultaneous observations of resolved stars and near-infrared (NIR) surface brightness across M31's entire bulge and disk (within R = 22 kpc), permitting a direct test of the stellar composition of near-infrared light in a nearby galaxy. Here we develop NIR observation and reduction methods to recover a uniform surface brightness map across the 3° × 1° disk of M31 with 27 WIRCam fields. Two sky-target nodding strategies are tested, and we find that strictly minimizing sky sampling latency cannot improve background subtraction accuracy to better than 2% of the background level due to spatio-temporal variations in the NIR skyglow. We fully describe our WIRCam reduction pipeline and advocate using flats built from night-sky images over a single night, rather than dome flats that do not capture the WIRCam illumination field. Contamination from scattered light and thermal background in sky flats has a negligible effect on the surface brightness shape compared to the stochastic differences in background shape between sky and galaxy disk fields, which are ~0.3% of the background level. The most dramatic calibration step is the introduction of scalar sky offsets to each image that optimizes surface brightness continuity. Sky offsets reduce the mean surface brightness difference between observation blocks from 1% to <0.1% of the background level, though the absolute background level remains statistically uncertain to 0.15% of the background level. We present our WIRCam reduction pipeline and performance analysis to give specific recommendations for the improvement of NIR wide-field imaging methods.

Sick, Jonathan; Courteau, Stéphane; Cuillandre, Jean-Charles; McDonald, Michael; de Jong, Roelof; Tully, R. Brent

2014-05-01

52

How a Change in Water Phase Affects Surface Temperatures  

NSDL National Science Digital Library

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

53

CCD Flatfielding for Strömvil Photometry in M 67  

Microsoft Academic Search

How obtain in the Strömvil system CCD photometry of one percent quality needed for subsequent stellar classification in temperature, surface gravity, reddening and metallicity? At the Vatican 1.8-meter telescope on Mt. Graham we always observe M 67 as a standard field. Laugalys et al. (Baltic Astronomy, 13, 1, 2004) demonstrate the quality of their CCD photometry in M 67 as

R. P. Boyle; R. Janusz; A. G. D. Philip; V. Laugalys; A. Kazlauskas

2005-01-01

54

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

55

Predictive Model of Surface Warfare Officer Retention: Factors Affecting Turnover.  

National Technical Information Service (NTIS)

Junior Surface Warfare Officer retention is in a crisis. The Surface Warfare Officer community anticipates an inability to fill Department Head billets due to the number of junior Surface Warfare Officers leaving military service. The goal of this study w...

G. D. Gjurich

1999-01-01

56

Third Workshop on Photometry  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

57

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

58

The 2060 Chiron: CCD photometry  

NASA Technical Reports Server (NTRS)

R-band CCD photometry of 2060 was carried out on nine nights in Nov. and Dec. 1986. The rotation period is 5.9181 + or - 0.0003 hr and the peak to peak lightcurve amplitude is 0.088 + or - 0.0003 mag. Photometric parameters are H sub R = 6.24 + or - 0.02 mag and G sub R = + or - 0.15, though formal errors may not be realistic. The lightcurve has two pairs of extrema, but its asymmetry, as evidenced by the presence of significant odd Fourier harmonics, suggests macroscopic surface irregularities and/or the presence of some large scale albedo variegation. The observational rms residual is + or - 0.015 mag. On time scales from minutes to days there is no evidence for nonperiodic (cometary) brightness changes at the level of a few millimagnitudes.

Bus, Schelte J.; Bowell, Edward; Harris, Alan W.

1987-01-01

59

What's Next in Asteroid Photometry  

NASA Astrophysics Data System (ADS)

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

Vander Haagen, Gary A.

2009-05-01

60

Results in speckle photometry  

NASA Astrophysics Data System (ADS)

Algorithms for reconstruction of isoplanically blurred point source pairs are considerably simpler and faster than full-blown image reconstruction techniques. Traditional autocorrelation approaches suffer from a 180 degree ambiguity, however, and only yield order of magnitude estimates for brightness ratios. A new asymmetric algorithm is here presented: the "Directed Vector Autocorrelation" (DVA), which is a rapid alternative to vector autocorrelation. Together with the 'Fork algorithm", a directional filter for estimating brightness ratios, the DVA algorithm has been used to resolve ambiguous orbits and produce differential color photometry for several binary stars.

Bagnuolo, W. G., Jr.; Barry, D. J.; Mason, B.; Dombrowski, E. G.

1990-08-01

61

How Direction of Illumination Affects Visually Perceived Surface Roughness  

PubMed Central

We examined visual estimation of surface roughness using random computer-generated three-dimensional (3D) surfaces rendered under a mixture of diffuse lighting and a punctate source. The angle between the tangent to the plane containing the surface texture and the direction to the punctate source was varied from 50 to 70 degrees across lighting conditions. Observers were presented with pairs of surfaces under different lighting conditions and indicated which 3D surface appeared rougher. Surfaces were viewed either in isolation or in scenes with added objects whose shading, cast shadows and specular highlights provided information about the spatial distribution of illumination. All observers perceived surfaces to be markedly rougher with decreasing illuminant angle. Performance in scenes with added objects was no closer to constant than that in scenes without added objects. We identified four novel cues that are valid cues to roughness under any single lighting condition but that are not invariant under changes in lighting condition. We modeled observers’ deviations from roughness constancy as a weighted linear combination of these “pseudo-cues” and found that they account for a substantial amount of observers’ systematic deviations from roughness constancy with changes in lighting condition.

Ho, Yun-Xian; Landy, Michael S.; Maloney, Laurence T.

2009-01-01

62

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

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

How strain affects the reactivity of surface metal oxide catalysts.  

PubMed

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

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

2013-12-16

65

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

66

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

67

Strip Photometry of Halley's Comet  

Microsoft Academic Search

Post-perihelical photometric observations of comet Halley were performed on 25 nights at the 50 cm reflector of UFRGS by the technique of strip photometry. A slit of dimensions 8arcmin×8arcsec scanned the comet image at a speed of 1arcsec.345 cos delta sec-1, in east-west direction or inversely. For photometry the authors used NASA interference filters C2, C3, CO+, H2O+, lambda4845 and

J. R. Ducati; T. S. Bergmann; C. Bonatto; R. L. Cavalcanti; R. D. D. Costa; H. A. Dottori; L. A. Girardi; D. Hadjimichef; S. O. Kepler; S. H. B. Livi; M. G. Pastoriza; J. F. Santos; A. Schmidt; M. F. S. Schröder

1986-01-01

68

Is there an optimal topographical surface in nanoscale affecting protein adsorption and cell behaviors?  

Microsoft Academic Search

With the development of nanotechnology, nano-structured surfaces exhibit superior biological activities to the smooth or micro-structured\\u000a surfaces. To study whether or not there is an optimal topographical surface in nano-scale affecting protein adsorption and\\u000a cell behaviors, aluminum oxide membranes with different topographical structures in nano-scale were prepared by anodic oxidation\\u000a technique. The surface morphology, topography, and wettability were analyzed by

Hua-Jie WangYing; Ying Cao; Yuan-Yuan Sun; Kui Wang; Cui Cao; Lin Yang; Yi-Dong Zhang; Zhi Zheng; Dan Li; Jin-Ye Wang; Yi-Long Han

69

PHOTOM: Photometry of digitized images  

NASA Astrophysics Data System (ADS)

PHOTOM performs photometry of digitized images. It has two basic modes of operation: using an interactive display to specify the positions for the measurements, or obtaining those positions from a file. In both modes of operation PHOTOM performs photometry using either the traditional aperture method or via optimal extraction. When using the traditional aperture extraction method the target aperture can be circular or elliptical and its size and shape can be varied interactively on the display, or by entering values from the keyboard. Both methods allow the background sky level to be either sampled interactively by the manual positioning of an aperture, or automatically from an annulus surrounding the target object. PHOTOM is the photometry backend for the GAIA tool (ascl:1403.024) and is part of the Starlink software collection (ascl:1110.012).

Eaton, Nicholas; Draper, Peter W.; Allan, Alasdair; Naylor, Tim; Mukai, Koji; Currie, Malcolm J.; McCaughrean, Mark

2014-05-01

70

Second Workshop on Improvements to Photometry  

NASA Technical Reports Server (NTRS)

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

Borucki, William J. (editor)

1988-01-01

71

Friction, wear, and surface damage of metals as affected by solid surface films  

NASA Technical Reports Server (NTRS)

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

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

1956-01-01

72

Voyager photometry of Iapetus  

NASA Astrophysics Data System (ADS)

Voyager images of Saturn's satellite Iapetus ranging in phase angle from 8 to 90 deg have been used to define the satellite's photometric properties and construct an albedo map of its surface. Iapetus shows variations in reflectance across its surface of a factor of 10 to 20, the greatest albedo range known for a solar system object. It is darkest at the apex of orbital motion, becomes brighter away from the apex, and is brightest near the poles. The 'boundary' between light and dark material is gradual rather than sharp. The photometric properties of the surface are adequately described by a lunarlike photometric function, but the surface phase function varies with albedo. The dark material on Iapetus is reddish, the bright material somewhat less so.

Squyres, S. W.; Buratti, B.; Veverka, J.; Sagan, C.

1984-09-01

73

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

74

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

Microsoft Academic Search

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

Alberto Fernández; Pilar Illera; Jose Luis Casanova

1997-01-01

75

RICHFLD photometry of NGC 6723  

NASA Astrophysics Data System (ADS)

New photographic photometry data for the globular cluster NGC 6723 are presented, and the implications for the CM diagram of the cluster are considered. Revisions to the photometry of Menzies (1974) are suggested which lead to a new value of E(B-V) = 0.10 + or - 0.05 mag. From analysis of the CM diagram and cluster apparent brightness distribution functions, the presence of a gap in the subgiant branch at V = 15.9 is suggested. This implies an uneven rate of evolution along the subgiant branch, similar to gaps seen by other observers for different clusters. Examination of the red end of the right horizontal branch suggests that there may be an extension in the form of an upper horizontal branch. This extension is compared with theoretical models, and agrees with predictions using Y = 0.2-0.3 and Z = 10 to the -4th.

Martins, Donald H.; Fraquelli, Dorothy A.

1987-09-01

76

Sources of error in the Tully-Fisher relation - Reducing the scatter with CCD I-band surface photometry of spiral galaxies  

NASA Astrophysics Data System (ADS)

We examine the sources of scatter in the H-band (1.6 m) Tully-Fisher (TF) relation and conclude that it is significantly larger than can be accounted for by observational errors. Using I-band luminosity profiles, we find that the major source of additional scatter stems from intrinsic variations in disk galaxy surface brightness at fixed line width. Moreover, curvature in the TF relation can result when apertures which are too small are used to measure the light in low line width galaxies. To correct for this behavior we have utilized a scheme where total I magnitudes are used for spirals with line widths less than 230 km s-1 and magnitudes within the I = 22.5 mag arcsec-2 isophote are used for galaxies of larger line width. Adhering to this scheme yields TF relations that have a scatter of 0.3 mag. However, if we use the distance-independent luminosity profile itself as a discriminant, we are able to produce an I-band TF relation which exhibits a scatter of only 0.2 mag. To take maximum advantage of this reduction in scatter, care must be taken to assemble a set of calibrating galaxies whose I-band surface brightness profiles most closely resemble those of H I selected spirals in distant clusters. Without a good match, the TF relation may never provide distances to individual galaxies that are better than 20%. In its practical application we find that the slope of I-band TF relation is quite similar for the Pisces and A2634 cluster samples. The implied difference in distance moduli is 1.07 ± 0.09, in good agreement with the value of 1.06 ± 0.15 derived by Aaronson et al. using the H-band TF relation. In addition, we have used the Pisces relation as a fiducial calibrating sequence to search for a zero point offset between a sample of field galaxies, most with redshifts greater than 3000 km s-1, that are located at the North and South Supergalactic Poles. Such an offset would reflect motion that is directed perpendicular to the supergalactic plane. No significant offset was found at a 1 ? limit of 350 km s-1.

Bothun, Gregory D.; Mould, Jeremy R.

1987-02-01

77

Surface shape affects the three-dimensional exploratory movements of nocturnal arboreal snakes.  

PubMed

Movement and searching behaviors at diverse spatial scales are important for understanding how animals interact with their environment. Although the shapes of branches and the voids in arboreal habitats seem likely to affect searching behaviors, their influence is poorly understood. To gain insights into how both environmental structure and the attributes of an animal may affect movement and searching, we compared the three-dimensional exploratory movements of snakes in the dark on two simulated arboreal surfaces (disc and horizontal cylinder). Most of the exploratory movements of snakes in the dark were a small fraction of the distances they could reach while bridging gaps in the light. The snakes extended farther away from the edge of the supporting surface at the ends of the cylinder than from the sides of the cylinder or from any direction from the surface of the disc. The exploratory movements were not random, and the surface shape and three-dimensional directions had significant interactive effects on how the movements were structured in time. Thus, the physical capacity for reaching did not limit the area that was explored, but the shape of the supporting surface and the orientation relative to gravity did create biased searching patterns. PMID:23052853

Jayne, Bruce C; Olberding, Jeffrey P; Athreya, Dilip; Riley, Michael A

2012-12-01

78

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

Microsoft Academic Search

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

Alberto Ferndndez; Pilar Illera; Jose Luis Casanova

79

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

80

The lenticular NGC 3115 - A standard for galaxy photometry  

NASA Astrophysics Data System (ADS)

NGC 3115, a lenticular galaxy that is seen edge-on, is an ideal candidate for surface photometry in virtue of its proximity and absence of close prominent companions. An independent two-dimensional study of NGC 3115 has been made using the high resolution CFH telescope, as well as the ESO and UK Schmidt telescopes (for the outer regions). Light profiles along both main axes were produced for each intensity frame; the results obtained are presented in graphical form.

Capaccioli, M.; Held, E. V.; Nieto, J.-L.

81

Asteroid Analysis Using Lightcurve Photometry  

NASA Astrophysics Data System (ADS)

During the summer of 2011 data was taken of asteroid 3807 Pagels, a mid-sized asteroid located in the main asteroid belt in order to identify its rotational period. The asteroid 3807 Pagels is a poorly studied main belt asteroid that has little information recorded about its physical features. Time-series photometry of 3807 Pagels was obtained with a 16-inch telescope connected to a CCD camera located at the Texas A&M University - Commerce Observatory. CCD images were taken continuously with five minute exposure times through the standard broadband V filter. The data was then analyzed using the MPO Canopus program which utilized comparison stars within each CCD image to determine differential photometry and then generate a lightcurve for the asteroid. The final lightcurve did not show a complete rotational period for the asteroid. Thus, additional observations are needed in order to precisely determine 3807 Pagels rotational period. This research is the first steps of a long process of determining more information about the many mid-sized asteroids located in the asteroid belt for the potential of being able to classify these asteroids by their physical characteristics.

Zimmerman, Jessica

2011-10-01

82

Fast photometry with small telescopes  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

83

Nanoscale topographic changes on sterilized glass surfaces affect cell adhesion and spreading.  

PubMed

Producing sterile glass surfaces is of great importance for a wide range of laboratory and medical applications, including in vitro cell culture and tissue engineering. However, sterilization may change the surface properties of glass and thereby affect its use for medical applications, for instance as a substrate for culturing cells. To investigate potential effects of sterilization on glass surface topography, borosilicate glass coverslips were left untreated or subjected to several common sterilization procedures, including low-temperature plasma gas, gamma irradiation and steam. Imaging by atomic force microscopy demonstrated that the surface of untreated borosilicate coverslips features a complex landscape of microislands ranging from 1000 to 3000 nm in diameter and 1 to 3 nm in height. Steam treatment completely removes these microislands, producing a nanosmooth glass surface. In contrast, plasma treatment partially degrades the microisland structure, while gamma irradiation has no effect on microisland topography. To test for possible effects of the nanotopographic structures on cell adhesion, human gingival fibroblasts were seeded on untreated or sterilized glass surfaces. Analyzing fibroblast adhesion 3, 6, and 24 h after cell seeding revealed significant differences in cell attachment and spreading depending on the sterilization method applied. Furthermore, single-cell force spectroscopy revealed a connection between the nanotopographic landscape of glass and the formation of cellular adhesion forces, indicating that fibroblasts generally adhere weakly to nanosmooth but strongly to nanorough glass surfaces. Nanotopographic changes induced by different sterilization methods may therefore need to be considered when preparing sterile glass surfaces for cell culture or biomedical applications. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2755-2766, 2014. PMID:24027204

Wittenburg, Gretel; Lauer, Günter; Oswald, Steffen; Labudde, Dirk; Franz, Clemens M

2014-08-01

84

Kir2.4 surface expression and basal current are affected by heterotrimeric G-proteins.  

PubMed

Kir2.4, a strongly rectifying potassium channel that is localized to neurons and is especially abundant in retina, was fished with yeast two-hybrid screen using a constitutively active G?o1. Here, we wished to determine whether and how G?o affects this channel. Using transfected HEK 293 cells and retinal tissue, we showed that Kir2.4 interacts with G?o, and this interaction is stronger with the GDP-bound form of G?o. Using two-electrode voltage clamp, we recorded from oocytes that were injected with Kir2.4 mRNA and a combination of G-protein subunit mRNAs. We found that the wild type and the inactive mutant of G?o reduce the Kir2.4 basal current, whereas the active mutant has little effect. Other pertussis-sensitive G? subunits also reduce this current, whereas G?s increases it. G?? increases the current, whereas m-phosducin, which binds G?? without affecting the state of G?, reduces it. We then tested the effect of G-protein subunits on the surface expression of the channel fused to cerulean by imaging the plasma membranes of the oocytes. We found that the surface expression is affected, with effects paralleling those seen with the basal current. This suggests that the observed effects on the current are mainly indirect and are due to surface expression. Similar results were obtained in transfected HEK cells. Moreover, we show that in retinal ON bipolar cells lacking G?3, localization of Kir2.4 in the dendritic tips is reduced. We conclude that G?? targets Kir2.4 to the plasma membrane, and G?o slows this down by binding G??. PMID:23339194

Sulaiman, Pyroja; Xu, Ying; Fina, Marie E; Tummala, Shanti R; Ramakrishnan, Hariharasubramanian; Dhingra, Anuradha; Vardi, Noga

2013-03-01

85

Kir2.4 Surface Expression and Basal Current Are Affected by Heterotrimeric G-Proteins*  

PubMed Central

Kir2.4, a strongly rectifying potassium channel that is localized to neurons and is especially abundant in retina, was fished with yeast two-hybrid screen using a constitutively active G?o1. Here, we wished to determine whether and how G?o affects this channel. Using transfected HEK 293 cells and retinal tissue, we showed that Kir2.4 interacts with G?o, and this interaction is stronger with the GDP-bound form of G?o. Using two-electrode voltage clamp, we recorded from oocytes that were injected with Kir2.4 mRNA and a combination of G-protein subunit mRNAs. We found that the wild type and the inactive mutant of G?o reduce the Kir2.4 basal current, whereas the active mutant has little effect. Other pertussis-sensitive G? subunits also reduce this current, whereas G?s increases it. G?? increases the current, whereas m-phosducin, which binds G?? without affecting the state of G?, reduces it. We then tested the effect of G-protein subunits on the surface expression of the channel fused to cerulean by imaging the plasma membranes of the oocytes. We found that the surface expression is affected, with effects paralleling those seen with the basal current. This suggests that the observed effects on the current are mainly indirect and are due to surface expression. Similar results were obtained in transfected HEK cells. Moreover, we show that in retinal ON bipolar cells lacking G?3, localization of Kir2.4 in the dendritic tips is reduced. We conclude that G?? targets Kir2.4 to the plasma membrane, and G?o slows this down by binding G??.

Sulaiman, Pyroja; Xu, Ying; Fina, Marie E.; Tummala, Shanti R.; Ramakrishnan, Hariharasubramanian; Dhingra, Anuradha; Vardi, Noga

2013-01-01

86

CHARACTERIZATION OF SLOAN DIGITAL SKY SURVEY STELLAR PHOTOMETRY  

SciTech Connect

We study the photometric properties of stars in the data archive of the Sloan Digital Sky Survey (SDSS), the prime aim being to understand the photometric calibration over the entire data set. It is confirmed that the photometric calibration of point sources is accurately on the system defined by the SDSS standard stars. We have also confirmed that the photometric synthesis of the SDSS spectrophotometric data gives broadband fluxes that agree with the photometry with errors of no more than 0.04 mag and little systematic tilt with wavelength. This verifies that the response functions of the 2.5 m telescope system are well characterized. We locate stars in the SDSS photometric system, so that stars can roughly be classified into spectral classes from the color information. We show how metallicity and surface gravity affect colors, and that stars contained in the SDSS general catalog, plotted in color space, show a distribution that matches well with what is anticipated from the variations of metallicity and surface gravity. The color-color plots are perfectly consistent among the three samples-stars in the SDSS general catalog, SDSS standard stars, and spectrophotometric stars of Gunn and Stryker-especially when some considerations are taken into account of the differences (primarily metallicity) of the samples. We show that the g - r-inverse temperature relation is tight and can be used as a good estimator of the effective temperature of stars over a fairly wide range of effective temperatures. We also confirm that the colors of G2V stars in the SDSS photometric system match well with the Sun.

Fukugita, Masataka [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 2778582 (Japan); Yasuda, Naoki; Doi, Mamoru [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 2778583 (Japan); Gunn, James E. [Princeton University Observatory, Princeton, NJ 08544 (United States); York, Donald G. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)

2011-02-15

87

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

PubMed Central

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

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

2014-01-01

88

Amylolytic hydrolysis of native starch granules affected by granule surface area.  

PubMed

Initial stage of hydrolysis of native starch granules with various amylolytic enzymes, alpha-amylase from Bacillus subtilis, glucoamylase I (GA-I) and II (GA-II) from Aspergillus niger, and beta-amylase from sweet potato showed that the reaction was apparently affected by a specific surface area of the starch granules. The ratios of the reciprocal of initial velocity of each amylolytic hydrolysis for native potato and maize starch to that for rice with the amylolytic enzymes were nearly equivalent to the ratio of surface area per mass of the 2 starch granules to that of rice, that is, 6.94 and 2.25, respectively. Thus, the reciprocal of initial velocity of each enzymatic hydrolysis as expressed in a Lineweaver-Burk plot was a linear function of the reciprocal of surface area for each starch granule. As a result, it is concluded that amylolytic hydrolysis of native starch granules is governed by the specific surface area, not by the mass concentration, of each granule. PMID:19021791

Kim, J C; Kong, B W; Kim, M J; Lee, S H

2008-11-01

89

Some factors that affect the surface measurement accuracy of a low-coherence interference microscope  

NASA Astrophysics Data System (ADS)

Low-coherence interference microscopy (LCIM) is a powerful imaging high-accuracy technique for surface inspection and profiling. The principle of this technique is based on the interference of two waves with the use of incoherent light, usually of halogen lamp or superluminescent diode. One of its principal advantages is that both the image intensity and the image phase may be extracted from the output signal. The image phase may be converted subsequently into the surface height data. The image intensity is depth discriminated in a similar way as in the confocal microscopy. A limited lateral resolving power of the microscope significantly influences the accuracy of profiling with LCIM. This factor affects not only the image intensity of the reconstructed signal, but also behaviour of the image phase. It could result in an error in surface-height data measurement, especially if the structure contains details, the size of which is comparable with the resolving power of the microscope. This paper deals with the deviation of measurement of one-dimensional and two-dimensional periodic surface structures in relation to the numerical aperture of the objective lens and to the spectral composition of the illumination. The calculations are based on the polychromatic coherent transfer function, which describes the influence of temporal and spatial coherence of illumination on the imaging characteristics of the LCIM. Experiments were done with the reflected-light low-coherence holographic microscope.

Lovicar, Lud?k; Chmelík, Radim; Komrska, Ji?í; Matoušková, Veronika; Kolman, Pavel; Foret, Zden?k

2007-05-01

90

Theory of wide-angle photometry from standard stars  

NASA Technical Reports Server (NTRS)

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.

1989-01-01

91

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.

92

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

93

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

94

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

95

CCD photometry of Comet P/Encke  

NASA Astrophysics Data System (ADS)

The authors present new photometry of Comet P/Encke taken near aphelion. Persistent cyclic variations in the brightness of the comet are attributed to rotation of the nucleus, with a most probable rotation period near 22.4 hr. The properties of the nucleus indicated by the new photometry do not compare favorably with the properties inferred from a model by Whipple and Sekanina (1979).

Jewitt, D.; Meech, K.

1987-06-01

96

Classification of stars with WBVR photometry  

NASA Astrophysics Data System (ADS)

We present a method of obtaining the most reliable stellar spectral type based on multi-color photometry. The method also allows us to estimate color excess EB-V and distance to the star. Approbation of the method using bright stars with known spectral classification and W BV R photometry permits to estimate its reliability. Stellar spectra models from Pickles (1998) library and Fluks et al. (1994) interstellar extinction law were used in the application of the method.

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

2013-10-01

97

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

98

L' AND M' Photometry Of Ultracool Dwarfs  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

99

BVRI Photometry of 53 Unusual Asteroids  

NASA Astrophysics Data System (ADS)

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

Ye, Q.-z.

2011-02-01

100

Meteor44 Video Meteor Photometry  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

101

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

2006-03-01

102

CDK5 interacts with Slo and affects its surface expression and kinetics through direct phosphorylation.  

PubMed

Large-conductance calcium-activated potassium (BK) channels are ubiquitous and play an important role in a number of diseases. In hair cells of the ear, they play a critical role in electrical tuning, a mechanism of frequency discrimination. These channels show variable kinetics and expression along the tonotopic axis. Although the molecular underpinnings to its function in hair cells are poorly understood, it is established that BK channels consist of a pore-forming ?-subunit (Slo) and a number of accessory subunits. Here we identify CDK5, a member of the cyclin-dependent kinase family, as an interacting partner of Slo. We show CDK5 to be present in hair cells and expressed in high concentrations in the cuticular plate and in the circumferential zone. In human embryonic kidney cells, we show that CDK5 inhibits surface expression of Slo by direct phosphorylation of Slo. Similarly, we note that CDK5 affects Slo voltage activation and deactivation kinetics, by a direct phosphorylation of T847. Taken together with its increasing expression along the tonotopic axis, these data suggest that CDK5 likely plays a critical role in electrical tuning and surface expression of Slo in hair cells. PMID:22094329

Bai, Jun-Ping; Surguchev, Alexei; Joshi, Powrnima; Gross, Liza; Navaratnam, Dhasakumar

2012-03-01

103

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

USGS Publications Warehouse

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

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

2006-01-01

104

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

105

Surface loading affects internal pressure source characteristics derived from volcano deformation signals  

NASA Astrophysics Data System (ADS)

Deformation of the Earth's surface provides critical information about the migration of material beneath a volcano. The resulting displacements, recorded by geodetic techniques such as GPS or InSAR, are used to infer characteristics of the volcanic plumbing system which are critical for hazard mitigation in volcanic regions. Given some deformation data, we search for the source model that explains the data best. Discussions of the results usually focus on the validity of the chosen model and the underlying assumptions regarding crustal composition, e.g. the level of inhomogeneity, elastic versus plastic deformation, thermal effects, depth vs. volume trade offs of the applied analytical models, or the (in-)compressibility of materials. Surface loads such as lava flows, however, provide an additional source of deformation. The initial elastic response due to a load on the surface of the Earth is followed by a visco-elastic response of the ductile crust below the uppermost elastic layer. Thus, a deformation signal recorded in the vicinity of a volcano is often composed of at least two contributors: an internal pressure source (the magma chamber) and a surface load (e.g., a composition of previously erupted lava flows) - at the extreme the volcanic edifice and its glaciers. A test case for a circular lava flow on top of a deflating magma chamber shows that the crust will adjust to the load towards final relaxed response. During this relaxation process gradual subsidence occurs that may mistakenly be interpreted as due to pressure decrease in a magma chamber since the deformation pattern of both processes are very similar. This poses a problem when characteristics of a magma chamber are to be derived. Based on the ratio of horizontal and vertical displacement and a combination of model results (Green's functions and Mogi model), we can estimate the composition of observed deformation signals. This method is applied to the Icelandic volcano Mt. Hekla where we investigate InSAR observations prior to the Hekla 2000 eruption that show circular pattern of near field subsidence and far field inflation. We compare these data to the deformation pattern expected from pressure changes in a hypothetical, shallow magma reservoir. We estimate surface loading at the volcano to account for a displacement of 13.5mm-yr based on a comparison of expected Mogi source and observed InSAR line of sight velocity. From this we estimate an effective relaxation time of tr = 100yrs for this region. We infer an elastic plate thickness of H = 3.5km which controls the 15 - 20km radius of subsidence. We find that surface load signals in volcanic regions affect magmatic source model estimates significantly ; to the point of changing the preferred source model. This effect should be considered in virtually any volcanic region that shows lava flow emplacement, glacier dynamics, or sudden load removal (i.e., lateral blasts). Deformation data that remains uncorrected will most likely result in an overestimation of depth and volume of a magma reservoir. We find that the ratio of displacements aids the identification of composite signals and suggest that the ratio for GPS data be employed more rigorously in future studies since this allows volume independent source depth estimates.

Grapenthin, Ronni; Sigmundsson, Freysteinn; Ofeigsson, Benedikt; Sturkell, Erik

2010-05-01

106

Improving Kepler Pipeline Sensitivity with Pixel Response Function Photometry.  

NASA Astrophysics Data System (ADS)

We present the results of our investigation into the feasibility and expected benefits of implementing PRF-fitting photometry in the Kepler Science Processing Pipeline. The Kepler Pixel Response Function (PRF) describes the expected system response to a point source at infinity and includes the effects of the optical point spread function, the CCD detector responsivity function, and spacecraft pointing jitter. Planet detection in the Kepler pipeline is currently based on simple aperture photometry (SAP), which is most effective when applied to uncrowded bright stars. Its effectiveness diminishes rapidly as target brightness decreases relative to the effects of noise sources such as detector electronics, background stars, and image motion. In contrast, PRF photometry is based on fitting an explicit model of image formation to the data and naturally accounts for image motion and contributions of background stars. The key to obtaining high-quality photometry from PRF fitting is a high-quality model of the system's PRF, while the key to efficiently processing the large number of Kepler targets is an accurate catalog and accurate mapping of celestial coordinates onto the focal plane. If the CCD coordinates of stellar centroids are known a priori then the problem of PRF fitting becomes linear. A model of the Kepler PRF was constructed at the time of spacecraft commissioning by fitting piecewise polynomial surfaces to data from dithered full frame images. While this model accurately captured the initial state of the system, the PRF has evolved dynamically since then and has been seen to deviate significantly from the initial (static) model. We construct a dynamic PRF model which is then used to recover photometry for all targets of interest. Both simulation tests and results from Kepler flight data demonstrate the effectiveness of our approach. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA’s Science Mission Directorate.Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA’s Science Mission Directorate.

Morris, Robert L.; Bryson, Steve; Jenkins, Jon Michael; Smith, Jeffrey C

2014-06-01

107

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

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

108

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, 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

109

Whiplash-associated disorders affect postural reactions to antero-posterior support surface translations during sitting.  

PubMed

Previous studies have shown that individuals with WAD display decreased postural stability during standing and walking tasks. However, their ability to maintain seated upright posture has never been investigated. The objective of this study was to characterize kinematic and electromyographic postural stabilization patterns in individuals with chronic WAD and to compare these patterns with those in an able-bodied control group. Ten individuals with WAD and an age- and gender-matched group of healthy individuals were exposed to sudden forward and backward support surface translations while they were seated. Neck and trunk muscle activity and angular displacements as well as centers of mass (COMs) linear displacements at four levels of the head and trunk were computed. The displacement onset of the combined head, arms and trunk COM was significantly delayed in persons with WAD. However, their peak trunk angles were smaller and were reached sooner. In the WAD group, the activation onset of the lumbar erector spinae was less affected by perturbation direction and the sternocleidomastoid muscle, a neck flexor, showed a trend towards being activated later, compared to the healthy group. These results suggest that individuals with WAD may alter stretch reflex threshold and/or elicit a learned response for pain avoidance that may be direction-specific. Such findings highlight the importance of assessing both spatial and temporal characteristics across different levels of the spinal musculoskeletal system to evaluate multidirectional postural responses in WAD individuals. PMID:19201611

Côté, Julie N; Patenaude, Isabelle; St-Onge, Nancy; Fung, Joyce

2009-06-01

110

Gaia photometry for white dwarfs  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

111

UBVRIJHK photometry of Dolidze 25 (Delgado+, 2010)  

NASA Astrophysics Data System (ADS)

Photometric color for 1673 stars in the direction of the young open cluster Dolidze 25. UBVRI CCD photometry, calibrated with previously published photoelectric values for some stars in the field, and the observations of standard fields. JHKs photometry, calibrated with matching to 2MASS data. The determination of cluster distance, reddening and age is carried out through comparison with ZAMS, post-MS and PMS isochrones. The reference lines used are obtained from theoretical post-MS and PMS isochrones from the Geneva and Yale groups, for metallicity Z=0.004, in agreement with the spectroscopic metallicity determination published for several cluster members. (1 data file).

Delgado, A. J.; Djupvik, A. A.; Alfaro, E. J.

2009-11-01

112

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

113

Spitzer IRAC Photometry of the 12 mu m Sample of Seyfert Galaxies  

Microsoft Academic Search

We present 3--8 mu m photometry of 80 Seyfert galaxies selected from the extended 12 mu m sample. The data were obtained by the IRAC aboard the Spitzer Space Telescope. We employed a surface brightness modeling and decomposition algorithm to isolate the contribution of the central point source from the surrounding host galaxy. The 3--8 mu m emission is potentially

J. C. Mannello; J. F. Gallimore; C. Buchanan; C. P. O'Dea; S. A. Baum; D. J. Axon; A. Robinson; M. Elitzur; M. Elvis

2005-01-01

114

Near-infrared photometry and spectroscopy of the unusual minor planet 5145 Pholus (1992AD)  

NASA Astrophysics Data System (ADS)

Near-IR photometry and spectroscopy of 5145 Pholus reveals that the visual to IR colors are unusually red and appear to show evidence for complex organic solids and/or ices on the surface. No compelling match is found with any present measurements of single-component ice or tholin samples.

Davies, J. K.; Sykes, M. V.; Cruikshank, D. P.

1993-03-01

115

Hipparcos photometry of CP stars (Adelman 1998)  

NASA Astrophysics Data System (ADS)

The Hipparcos photometry of the chemically peculiar main-sequence B, A and F stars are examined for variability. Some non-magnetic CP stars, Mercury-Manganese and metallic-line stars, which according to canonical wisdom should not be variable, may be variable and are identified for further study. Some potentially important magnetic CP stars are noted. (3 data files).

Adelman, S. J.

1998-06-01

116

HST BVI Photometry of Triton and Proteus.  

National Technical Information Service (NTIS)

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 gr...

A. D. Storrs D. Pascu E. N. Wells J. L. Hershey J. R. Rohde

2006-01-01

117

Photometry from online Digitized Sky Survey plates  

NASA Astrophysics Data System (ADS)

Online Digitized Sky Survey (DSS) material is often used to obtain information on newly discovered variable stars for older epochs (e.g. Nova progenitors, flare stars, etc.). We present here the results of an investigation of photometry on online DSS material in small fields calibrated by CCD sequences. We compared different source extraction mechanisms and found that even down near to the sensitivity limit, despite the H-compression used for the online material, photometry with an accuracy better than 0.1 mag rms is possible on DSS-II. Our investigation shows that the accuracy depends strongly on the source extraction method. The SuperCOSMOS scans, although retrieved with a higher spatial resolution, do not give us better results. The methods and parameters presented here allow the user to obtain good plate photometry in small fields down to the Schmidt plate survey limits with a few bright CCD calibrators, which may be calibrated with amateur-size telescopes. Especially for the events mentioned above, new field photometry for calibration purposes mostly exists, but the progenitors were not measured photometrically before. Also, the follow-up whether stellar concentrations are newly detected clusters or similar work may be done without using mid-size telescopes. The calibration presented here is a `local' one for small fields. We show that the method presented here gives higher accuracies than `global' calibrations of surveys (e.g. Guide Star Catalogue-II (GSC-II), SuperCOSMOS and the US Naval Observatory Astrometry Catalog B).

Bacher, A.; Kimeswenger, S.; Teutsch, P.

2005-09-01

118

Narrow Band Photometry of Selected Asteroids.  

National Technical Information Service (NTIS)

The CCD photometry of selected asteroids was carried out to check for possible cometary activity in them. To distinguish the asteroids with possible cometary activity from those of the main belt, each object of interest was observed in two filters; one ce...

R. Rajamohan S. G. Bhargavi

1992-01-01

119

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.

120

TERMS Photometry of Known Transiting Exoplanets  

Microsoft Academic Search

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

Diana Dragomir; Stephen R. Kane; Genady Pilyavsky; Suvrath Mahadevan; David R. Ciardi; J. Zachary Gazak; Dawn M. Gelino; Alan Payne; Markus Rabus; Solange V. Ramirez; Kaspar von Braun; Jason T. Wright; Pamela Wyatt

2011-01-01

121

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

122

Subtle changes in surface chemistry affect embryoid body cell differentiation: lessons learnt from surface-bound amine density gradients.  

PubMed

Advanced approaches to direct the differentiation of embryonic stem cells are highly sought after. The surface-bound chemical gradient format is a powerful screening approach that can be deployed to study changes in stem cell behavior as a function of subtle changes in surface chemistry. Here, we investigate the spontaneous differentiation of cells derived from differentiating mouse embryoid body (mEB) cells into endoderm, mesoderm, and ectoderm following culture on surface-bound gradients of chemical functional groups in the absence of differentiation-biasing bioactive factors. Gradients were created using a diffusion-controlled plasma polymerization technique. The generated coating ranged from hydrophobic 1,7-octadiene (OD) plasma polymer at one end of the gradient to a more hydrophilic allylamine (AA) plasma polymer on the opposite end. The gradient surface was divided into seven equal regions of progressively increasing AA plasma polymer content and mEB cell response within these regions was compared. Cells adhered preferentially to the central regions of the gradient; however, cell proliferation increased toward AA-plasma-polymer-rich end of the gradient. Variation in the expression of germ layer markers was noted across the gradient surface. High AA:OD plasma polymer ratios triggered cell differentiation toward both mesoderm and ectoderm. Expression of tissue-specific markers, in particular, KRT18, AFP, and TNNT2, was strikingly responsive to subtle changes in surface chemistry, exhibiting vastly different expression levels between adjacent regions. Our results suggest that the surface-bound gradient platform is well suited to screening surface chemistries for use in the field of stem cell technologies and regenerative medicine. PMID:24354633

Delalat, Bahman; Goreham, Renee V; Vasilev, Krasimir; Harding, Frances J; Voelcker, Nicolas H

2014-06-01

123

Nanoscale roughness and morphology affect the IsoElectric Point of titania surfaces.  

PubMed

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

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

2013-01-01

124

Nanoscale Roughness and Morphology Affect the IsoElectric Point of Titania Surfaces  

PubMed Central

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

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

2013-01-01

125

Infrared Photometry for Automated Telescopes: Passband Selection  

NASA Astrophysics Data System (ADS)

The high precision that photometry in the near and intermediate infrared region can provide has not been achieved, partly because of technical challenges (including cryogenics, which most IR detectors require), and partly because the filters in common use are not optimized to avoid water-vapor absorptions, which are the principal impediment to precise ground-based IR photometry. We review the IRWG filters that achieve this goal, and the trials that were undertaken to demonstrate their superiority. We focus especially on the near IR set and, for high elevation sites, the passbands in the N window. We also discuss the price to be paid for the improved precision, in the form of lower throughput, and why it should be paid: to achieve not only higher precision (i.e., improved signal-to-noise ratio), but also lower extinction, thus producing higher accuracy in extra-atmospheric magnitudes. The edges of the IRWG passbands are not defined by the edges of the atmospheric windows: therefore, they admit no flux from these (constantly varying) edges. The throughput cost and the lack of a large body of data already obtained in these passbands are principal reasons why the IRWG filters are not in wide use at observatories around the world that currently do IR work. Yet a measure of the signal-to-noise ratio varies inversely with both extinction and with a measure of the Forbes effect. So, the small loss of raw throughput is recouped in signal-to-noise gain. We illustrate these points with passbands of both near and intermediate IR passbands. There is also the matter of cost for small production runs of these filters; reduced costs can be realized through bulk orders with uniform filter specifications. As a consequence, the near-IR IRWG passbands offer the prospect of being able to do photometry in those passbands at both high and low elevation sites that are capable of supporting precise photometry, thereby freeing infrared photometry from the need to access exclusively high and dry elevation sites, although photometry done at those sites can also benefit from improved accuracy and transformability. We suggest that if the IRWG passbands are made available, they will be used! New automated systems making use of these passbands have the advantage of establishing the system more widely, creating a larger body of data to which future observations will be fully transformable, and will be cheaper to purchase. This work has been supported in part by grants to EFM by the Canadian Natural Sciences and Engineering Research Council.

Milone, Gene; Young, Andrew T.

2011-03-01

126

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

NASA Astrophysics Data System (ADS)

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

Wei, Kang; Zeng, Hansong; Zhao, Yi

2013-05-01

127

How Suspended Particles Affect Surface Morphology in Powder Mixed Electrical Discharge Machining (PMEDM)  

NASA Astrophysics Data System (ADS)

The effect of SiC powder mixing into the dielectric liquid on surface topology and structure of interstitial free (IF) steel has been studied. Four process parameters, namely pulse duration, pulse current, concentration of powder, and type of dielectric liquid material, have been selected as varying parameters. Surface modifications due to suspended SiC particles were identified by using optical, scanning electron microscopy, and X-ray diffraction analysis. It was observed that suspended particles around discharge column accelerated and gained sufficient velocity to penetrate to the molten pool before solidification by means of electrophoresis and negative pressure induced after cessation of a discharge, which leads a surface embedded with added fine particles under that prevent formation of penetrating cracks during machining. However, surface cracks that formed due to high transformational stresses developed during solidification were found to be unaffected by means of mechanical action of the particles.

Ekmekci, Bülent; Ersöz, Yusuf

2012-10-01

128

Adding a Performance-Based Component to Surface Warfare Officer Bonuses: Will it Affect Retention.  

National Technical Information Service (NTIS)

The Surface Warfare Officer (SWO) community has difficulty retaining mid-grade officers, as is evident by the considerable shortfall between Officer Programmed Authorization and the current officer inventory beginning at 9 years of commissioned service. T...

A. S. Carman R. M. Mudd

2008-01-01

129

Small Surface Pretilt Strikingly Affects the Director Profile during Poiseuille Flow of a Nematic Liquid Crystal  

NASA Astrophysics Data System (ADS)

Conventional nematic liquid crystal cells are fabricated with small surface pretilt of the director induced by rubbed polymer alignment. Depending on the orientation of the bounding surfaces, this may lead to two slightly different untwisted director configurations, splay and parallel. This small difference leads to remarkably different director profiles during pressure-driven flow, observed here using optical conoscopy. Data show excellent agreement with numerical modeling from Leslie-Ericksen-Parodi theory.

Holmes, C. J.; Cornford, S. L.; Sambles, J. R.

2010-06-01

130

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

131

Learning beyond the Surface: Engaging the Cognitive, Affective and Spiritual Dimensions within the Curriculum  

ERIC Educational Resources Information Center

In Australia the separation of mind, body and spirit by secular society has had a significant influence on educational trends. An outcomes-based approach to education, with an emphasis on cognitive learning, has meant that the affective and spiritual dimensions of students' lives have often been understated. Classroom programs in religious…

Buchanan, Michael T.; Hyde, Brendan

2008-01-01

132

2060 Chiron - CCD and electronographic photometry  

NASA Astrophysics Data System (ADS)

R-band observations conducted for 2060 Chiron using CCD photometry in November-December 1986 and March 1988 are discussed. While the 1986 observations exhibit neither periodic nor nonperiodic brightness changes ascribable to comet-like activity, the 1988 observations show an 0.6 + or - 0.1 mag brightening that confirms the Tholen et al. (1988) findings and is consistent with the 1978 electronographic photometry presented. The lightcurve amplitudes appear, however, to have remained unchanged from 1978 to 1988, and the image profiles from 1978 are indistinguishable from the stars in 1986 and 1988. It is suggested that Chiron has either been varying nonasteroidally of late, on a 1-2 month timescale, or its intrinsic brightness has been bistable over the past decade.

Bus, Schelte J.; Bowell, Edward; Harris, Alan W.; Hewitt, Anthony V.

1989-02-01

133

2060 Chiron - CCD and electronographic photometry  

NASA Technical Reports Server (NTRS)

R-band observations conducted for 2060 Chiron using CCD photometry in November-December 1986 and March 1988 are discussed. While the 1986 observations exhibit neither periodic nor nonperiodic brightness changes ascribable to comet-like activity, the 1988 observations show an 0.6 + or - 0.1 mag brightening that confirms the Tholen et al. (1988) findings and is consistent with the 1978 electronographic photometry presented. The lightcurve amplitudes appear, however, to have remained unchanged from 1978 to 1988, and the image profiles from 1978 are indistinguishable from the stars in 1986 and 1988. It is suggested that Chiron has either been varying nonasteroidally of late, on a 1-2 month timescale, or its intrinsic brightness has been bistable over the past decade.

Bus, Schelte J.; Bowell, Edward; Harris, Alan W.; Hewitt, Anthony V.

1989-01-01

134

CCD and photographic photometry of NGC 1904  

NASA Astrophysics Data System (ADS)

Combined CCD and photographic photometry of the globular cluster NGC 1904 are presented. The data reduction procedures for the CCD and digital iris photometry are presented. The cluster's C-M diagram is nearly identical in morphology to that of the nearby globular cluster M13, the only significant difference being the subgiant branch, where the NGC 1904 ridge line is flatter than in M13. If a cluster age of 16 Gyr, as suggested by theoretical models, is adopted, the turnoff and main-sequence region in the C-M diagram are fit by VandenBerg's (1983) isochrone for Y = 0.20 and Z = 0.001 for a distance modulus of 15.65 and a reddening of 0.01. If the cluster is more metal-poor, as suggested by Zinn and West (1984), then an older isochrone is required to match the observations.

Heasley, J. N.; Janes, K. A.; Christian, C. A.

1986-05-01

135

Introducing SPA, "The Stellar Photometry Assistant"  

NASA Astrophysics Data System (ADS)

The Stellar Photometry Assistant, SPA, is a stand alone software package for time-series photometry reduction and analysis slated for an initial test release in spring 2008. The goal of SPA is to be simple, powerful, and intuitive. SPA was born out of complications in studying the pulsating DB white dwarf EC20058-5234 (QU Tel) due to the proximity of its nearby companions. SPA also addresses the Whole Earth Telescope's (WET) demand for large scale rapid data reduction from multiple sites. SPA is being developed in Matlab by the Delaware Asteroseismologic Research Center (DARC) in collaboration with the University of Delaware and the Mount Cuba Astronomical Observatory. The need for SPA is addressed, and key features of the program are listed and discussed.

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

2008-06-01

136

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

PubMed

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

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

2014-05-01

137

Narrow band photometry of selected asteroids  

NASA Technical Reports Server (NTRS)

The CCD photometry of selected asteroids was carried out to check for possible cometary activity in them. To distinguish the asteroids with possible cometary activity from those of the main belt, each object of interest was observed in two filters; one centered on the C2 emission band at 5140A (90A bandpass) and the other centered on the nearby continuum at 4845A (65A bandpass). None of the observed asteroids appear to have any C2 emission.

Rajamohan, R.; Bhargavi, S. G.

1992-01-01

138

Infrared (JHK) photometry of asteroids. II  

NASA Technical Reports Server (NTRS)

JHK (1.2, 1.6, and 2.2 micron) photometry for 38 asteroids of various spectral classifications is reported. M asteroids tend to have infrared colors intermediate between the color domains of E and P asteroids. A few D asteroids have redder J - H colors than most C asteroids. The unusually red J - H color of 246 Asporina indicates it is a member of the A class.

Veeder, G. J.; Matson, D. L.; Hoover, G.; Kowal, C.

1983-01-01

139

Recalibrating SFD Using SDSS Spectroscopy And Photometry  

NASA Astrophysics Data System (ADS)

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

Schlafly, Eddie; Finkbeiner, D. P.

2011-05-01

140

Lightcurve Photometry Opportunities: 2014 July-September  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

141

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

142

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

PubMed

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

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

2014-01-01

143

Cholesterol level affects surface charge of lipid membranes in saline solution  

PubMed Central

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

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

2014-01-01

144

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

145

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-...

146

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

147

Physiological variables affecting surface film formation by native lamellar body-like pulmonary surfactant particles.  

PubMed

Pulmonary surfactant (PS) is a surface active complex of lipids and proteins that prevents the alveolar structures from collapsing and reduces the work of breathing by lowering the surface tension at the alveolar air-liquid interface (ALI). Surfactant is synthesized by the alveolar type II (AT II) cells, and it is stored in specialized organelles, the lamellar bodies (LBs), as tightly packed lipid bilayers. Upon secretion into the alveolar lining fluid, a large fraction of these particles retain most of their packed lamellar structure, giving rise to the term lamellar body like-particles (LBPs). Due to their stability in aqueous media, freshly secreted LBPs can be harvested from AT II cell preparations. However, when LBPs get in contact with an ALI, they quickly and spontaneously adsorb into a highly organized surface film. In the present study we investigated the adsorptive capacity of LBPs at an ALI under relevant physiological parameters that characterize the alveolar environment in homeostatic or in pathological conditions. Adsorption of LBPs at an ALI is highly sensitive to pH, temperature and albumin concentration and to a relatively lesser extent to changes in osmolarity or Ca(2+) concentrations in the physiological range. Furthermore, proteolysis of LBPs significantly decreases their adsorptive capacity confirming the important role of surfactant proteins in the formation of surface active films. PMID:24582711

Hobi, Nina; Siber, Gerlinde; Bouzas, Virginia; Ravasio, Andrea; Pérez-Gil, Jesus; Haller, Thomas

2014-07-01

148

Determination of key variables affecting surface properties of UV curable coatings using experimental design  

Microsoft Academic Search

The influence of prepolymer (urethane acrylate or polyesteracrylate) type, triacrylate (trimethyolpropane triactylate or ethoxylated trimethylolpropane triacrylate) type and the concentration of silicone acrylate on the surface properties of UV cured films was studied. The effect of these variables on the pencil hardness and gloss was determined by using a full factorial experimental design. The results showed that the prepolymer type

H. K. Kim; J. G. Kim; J. W. Hong

2002-01-01

149

Factors affecting temperature rise on the external root surface during ultrasonic retrieval of intracanal separated files.  

PubMed

Temperature rise (TR) on the external root surface during ultrasonic removal of separated files (SFs) from 50 lower incisors roots of 10-mm length was investigated. CPR ultrasonic tips (Obtura-Spartan, Fenton, MO) were used dry to retrieve F2 ProTaper (Dentsply, Surrey, UK) segments fractured 2.5 mm from the coronal access in five groups: CPR2, CPR5, and CPR6 at power setting 1 and CPR5 at power settings 2.5 and 5. Temperature changes were inspected at 30-second intervals up to 120 seconds at three different sites: two at mesiodistal and buccolingual surfaces adjacent to the most coronal aspect of the SF and the third adjacent to the most apical aspect. Overall, the highest mean TR was at the buccolingual root surface followed by that at the mesiodistal and the more apical site surfaces. At power setting 1, CPR6 produced a significantly lower TR than CPR5, and both can be used for 120 and 60 seconds, respectively. Power setting 5 is not recommended for the removal of SF because this induces a hazardous TR. PMID:18718371

Madarati, Ahmad A; Qualtrough, Alison J; Watts, David C

2008-09-01

150

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

151

Gold nanoparticles induce surface morphological transformation in polyurethane and affect the cellular response.  

PubMed

Nanocomposites from a hexamethylene diisocyanate (HDI)-based polyester-type waterborne polyurethane (PU) containing different amounts (17.4-174 ppm) of gold (Au) nanoparticles (approximately 5 nm) were prepared. The microstructure and physiochemical properties of the nanocomposites were characterized. The cell attachment and proliferation, platelet activation, and bacterial adhesion on the nanocomposites were evaluated. Gold nanoparticles in small amounts induced significant changes in surface morphology and domain structures, from hard segment lamellae to soft segment micelles. These changes resembled the morphological transformation among different mesophases occurred in diblock copolymers. Better cellular proliferation, lower platelet activation, and reduced bacterial adhesion were demonstrated for the PU nanocomposite with 43.5 or 65 ppm of Au than the pure PU or the nanocomposite containing a different amount of Au. The different cellular response on PU-Au nanocomposites was attributed to the extensively modified surface morphology and phase separation in the presence of a small amount of Au nanoparticles. PMID:18163574

Hsu, Shan-hui; Tang, Cheng-Ming; Tseng, Hsiang-Jung

2008-01-01

152

How do hydrogen atoms on surfaces affect the trajectories of heavier scattered atoms?  

NASA Astrophysics Data System (ADS)

The recently developed technique of scattering and recoiling imaging spectrometry (SARIS) is used to probe the effect of hydrogen atoms on the trajectories of 5 keV Ne+ scattering from a Pt(111) surface. Classical kinematic calculations and ion trajectory simulations, using the scattering and recoiling imaging code (SARIC), are carried out in order to probe the details of the interaction and the nature of the perturbation. It is demonstrated that adsorbed hydrogen atoms are capable of deflecting these low kilo-electron-volt Ne trajectories scattering from a Pt surface. These perturbations result in spatial shifts and broadenings of the anisotropic features of the SARIS images that are readily detectable. The scattered Ne atoms lose 0-18% of their initial kinetic energy as a result of the perturbation by the H atoms. The physics of the perturbation on the trajectories can be understood from straightforward classical kinematic calculations and SARIC ion trajectory simulations.

Lui, K. M.; Bolotin, I.; Kutana, A.; Bykov, V.; Lau, W. M.; Rabalais, J. W.

1999-12-01

153

Surface Residue and Soil Moisture Affect Fertilizer Loss in Simulated Runoff on a Heavy Clay Soil  

Microsoft Academic Search

age systems. These systems are known to be very effec- tive in reducing erosion and limiting the amount of The potential for non-point-source pollution of surface waters from nutrients that leave the field in sediment (McDowell agricultural lands continues to be a concern. Our objective was to and McGregor, 1984; Angle et al., 1984; Romkens et determine the effect of

H. Allen Torbert; Kenneth N. Potter; Dennis W. Hoffman; Thomas J. Gerik; C. W. Richardson

1999-01-01

154

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

155

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

Microsoft Academic Search

Surfactant protein A (SP-A) is an abundant protein found in pulmonary surfactant which has been reported to have multiple functions. In this review, we focus on the structural importance of each domain of SP-A in the functions of protein oligomerization, the structural organization of lipids and the surface-active properties of surfactant, with an emphasis on ultrastructural analyses. The N-terminal domain

Nades Palaniyar; Machiko Ikegami; Thomas Korfhagen; Jeffrey Whitsett; Francis X McCormack

2001-01-01

156

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

PubMed Central

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

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

2012-01-01

157

Cell surface sialylation affects binding of enterovirus 71 to rhabdomyosarcoma and neuroblastoma cells  

PubMed Central

Background Enterovirus 71 (EV71) is a major causative agent of hand-foot-and-mouth disease (HFMD), and infection of EV71 to central nerve system (CNS) may result in a high mortality in children less than 2?years old. Although there are two highly glycosylated membrane proteins, SCARB2 and PSGL-1, which have been identified as the cellular and functional receptors of EV71, the role of glycosylation in EV71 infection is still unclear. Results We demonstrated that the attachment of EV71 to RD and SK-N-SH cells was diminished after the removal of cell surface sialic acids by neuraminidase. Sialic acid specific lectins, Maackia amurensis (MAA) and Sambucus Nigra (SNA), could compete with EV71 and restrained the binding of EV71 significantly. Preincubation of RD cells with fetuin also reduced the binding of EV71. In addition, we found that SCARB2 was a sialylated glycoprotein and interaction between SCARB2 and EV71 was retarded after desialylation. Conclusions In this study, we demonstrated that cell surface sialic acids assist in the attachment of EV71 to host cells. Cell surface sialylation should be a key regulator that facilitates the binding and infection of EV71 to RD and SK-N-SH cells.

2012-01-01

158

Photometry of AM Herculis - A slow optical pulsar  

NASA Technical Reports Server (NTRS)

Multicolor photometry of the X-ray binary AM Her suggests that the red component of the optical flux is closely related to the source of optical circular polarization in the system. It is concluded from the periodic modulation of flux in the U through R bands, which is particularly well-defined when plotted as color curves, that the primary and secondary minima are neither eclipses by a secondary star nor eclipses by a hot spot. It is suggested that the primary minimum in the visual light curve is the eclipse of a region of intense optical emission in the magnetic field near the surface of a degenerate dwarf by that dwarf itself.

Priedhorsky, W. C.; Krzeminski, W.

1978-01-01

159

Optimization of formulation variables affecting spray-dried oily core nanocapsules by response surface methodology.  

PubMed

The formulation variables required for the production of spray-dried oily core nanocapsules (NCs) with targeted size and drug payload were optimized using a Box-Behnken experimental design. These NCs were characterized for size, morphology, encapsulation efficiency (EE%) and drug release kinetics, crystallinity, and density, by dynamic light scattering, electron microscopy, ultraviolet spectrometry, powder X-ray diffraction, and density-gradient centrifugation, respectively. The size of the NCs ranged from 208.6 to 504.4 nm, with EE% from 64.7% to 94.6%. The amounts of oil and surfactant (Pluronic F127) significantly affected size. The amounts of polymer [polylactide (PLA)], oil, and surfactant significantly affected EE%. The optimum formulation parameters were set to be 300 mg of PLA, 0.56 mL of oil, and 239.57 mg of Pluronic F127, which corresponded to size of 284.1 nm and EE% of 95.7%. Morphological analysis and density-gradient centrifugation showed the existence of an oily core and spherical nanostructure with no detectable drug crystals. The NCs had longer sustained drug release than nanosphere control, with a good fit to the Ritger-Peppas model (R(2) > 0.930). Spray-dried oily core NCs were successfully produced, and the Box-Behnken design appears to be an effective tool to predict the size and encapsulation of NCs. PMID:20928871

Zhang, Tao; Murowchick, James; Youan, Bi-botti C

2011-03-01

160

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

NASA Astrophysics Data System (ADS)

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

Dickinson, Michelle Emma

161

Precision photometry and variability of massive stars from space  

NASA Astrophysics Data System (ADS)

While the satellites CoRoT and Kepler, launched in 2007 and 2010, have recently provided long, intense time-series of precision photometric data for a few fairly massive stars, they are limited in sky coverage and are mainly dedicated to asteroseismology of lower-mass stars and transits of exoplanets. On the other hand, the MOST mission has been operating since 2003 and reaches a much larger swath of sky. I will examine what has been done to date in the area of precision time-dependent optical photometry of massive stars, primarily from space. Of particular interest is the MOST photometry of eight bright WR stars of various subtypes: While few if any pulsations have been detected down to a level well below 1 mmag, a new paradigm appears to be emerging: the frequent presence of quasi-periodic, cuspy-like photometric variations in mainly later-type WN and WC stars. This variability (up to several percent) may be related to non-radial pulsations of the underlying star, or more likely, magnetic spots ultimately generated by newly revealed sub-surface convection in hot luminous stars, which may be especially prevalent in deeper surface layers of cooler late-type WR stars. Such localized (hot) spots could also be the drivers of Corotating Interaction Regions linked to rotation of the underlying star. Similar results appear to be forthcoming for O stars as well. The soon-to-be-launched nanosatellite array BRITE-Constellation will concentrate on variability of a large number of naked-eye luminous stars.

Moffat, Anthony F. J.

2013-06-01

162

Extracting Photometry Measurements from VizieR Catalogs  

NASA Astrophysics Data System (ADS)

Photometry measurements in astronomical catalogs cover a wide range of spectral bandpasses with many different photometric systems and units. The VizieR Catalog service has recently extended the standardized description of catalogs to include photometry . This includes the observed frequency and bandwidth in GHz and conversion of magnitudes and other units to flux densities in Jy. We present various prototype interfaces for extracting and combining photometry across multiple catalogs and discuss the uses and limitations of this service.

Allen, M. G.; Ochsenbein, F.; Derriere, S.; Boch, T.; Fernique, P.; Landais, G.

2014-05-01

163

Erratum: High-Precision Photometry of Extreme Kbo 2003 EL61" (2008, AJ, 135, 1749)  

NASA Astrophysics Data System (ADS)

We report an error in Table 3 of the original paper: the UT and Julian dates, Columns 1 and 2, and the photometry, Column 3, are misaligned below row 153. The corrected version of Table 3 is presented herein. These corrections are only typographical in nature, and none of the results or conclusions of the paper are affected. We acknowledge Daniel C. Fabrycky for detecting this error.

Lacerda, Pedro; Jewitt, David; Peixinho, Nuno

2008-10-01

164

Photometry with Multi-Anode Microchannel Arrays (MAMAs) and Charge Injection Devices (CIDs)  

NASA Technical Reports Server (NTRS)

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

Timothy, J. G.

1984-01-01

165

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

166

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

2010-03-31

167

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

USGS Publications Warehouse

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

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

2010-01-01

168

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

169

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

PubMed

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

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

2001-05-01

170

Water color affects the stratification, surface temperature, heat content, and mean epilimnetic irradiance of small lakes  

USGS Publications Warehouse

The effects of water color on lake stratification, mean epilimnetic irradiance, and lake temperature dynamics were examined in small, north-temperate lakes that differed widely in water color (1.5-19.8 m -1). Among these lakes, colored lakes differed from clear lakes in the following ways: (i) the epilimnia were shallower and colder, and mean epilimnetic irradiance was reduced; (ii) the diel temperature cycles were more pronounced; (iii) whole-lake heat accumulation during stratification was reduced. The depth of the epilimnion ranged from 2.5 m in the clearest lake to 0.75 m in the most colored lake, and 91% of the variation in epilimnetic depth was explained by water color. Summer mean morning epilimnetic temperature was ???2??C cooler in the most colored lake compared with the clearest lake. In clear lakes, the diel temperature range (1.4 ?? 0.7??C) was significantly (p = 0.01) less than that in the most colored lake (2.1 ?? 1.0??C). Change in whole-lake heat content was negatively correlated with water color. Increasing water color decreased light penetration more than thermocline depth, leading to reduced mean epilimnetic irradiance in the colored lakes. Thus, in these small lakes, water color significantly affected temperature, thermocline depth, and light climate. ?? 2006 NRC.

Houser, J. N.

2006-01-01

171

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

PubMed Central

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

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

2013-01-01

172

Proliferation of purple sulphur bacteria at the sediment surface affects intertidal mat diversity and functionality.  

PubMed

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

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

2013-01-01

173

BVRI photometry of HR 1105 (Adelman 1998)  

NASA Astrophysics Data System (ADS)

BVRI photometry of the extrinsic S star HR 1105 shows a stable periodic light variability with a period of 24.76 days superimposed upon long term changes presumably related to the orbital period. The variations are in phase for all four magnitudes with the amplitude of this variability being about the same for B and V, but smaller for R and even smaller for I. As the primary is a M3 III star, these brightness changes are mostly likely due to the pulsation of the primary star. (1 data file).

Adelman, S. J.

1998-02-01

174

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

175

Differential photometry of FK Com (Korhonen+, 2007)  

NASA Astrophysics Data System (ADS)

In the present work we publish new photometric observations of the very active single giant, FK Com for the time period between the 1st of January 2002 and the 8th of July 2004. The observations have been carried out with three different automatic photometric telescopes: Phoenix 10, Wolfgang and Amadeus, all located in Arizona, USA. Observations contain measurements at the following bands: Johnson U, B and V, Cousins I and Stroemgren b and y. The observations are differential photometry in respect to the primary comparison star HD 117567. (3 data files).

Korhonen, H.; Berdyugina, S. V.; Hackman, T.; Ilyin, I. V.; Strassmeier, K. G.; Tuominen, I.

2007-10-01

176

Photometry of six radar target asteroids  

NASA Technical Reports Server (NTRS)

Photoelectric photometry of six earth-approaching asteroids is presented. The selection criterion was that they were close enough in 1986 to be observed by radar. Rotation periods were obtained for 1986 DA, 3199, 3103, and 1983 RD. 1986 JK and 1986 RA showed no detectable brightness variations during the monitoring time on several nights each, and therefore were either seen pole-on or have long rotation periods. Asteroids 1986 JK and 1986 RA are of taxonomic class C, 1986 DA and 3103 of class X, 1983 RD of class Q, and only 3199 of the class S that was previously believed to be predominant among earth-approaching asteroids.

Wisniewski, W. Z.

1987-01-01

177

How fulvic acid affects heavy metal uptake on the muscovite (001) surface  

NASA Astrophysics Data System (ADS)

Understanding the molecular-scale reactions at mineral-solution interfaces is crucial for developing predictive models to assess the transport and bioavailability of dissolved heavy metals in the surface environment. We investigated the vertical distribution of divalent heavy metals (Cu, Zn, Sr, Hg, and Pb) adsorbed at the muscovite (001)-solution interface in the absence and presence of fulvic acid (FA) using interface-specific specular X-ray reflectivity combined with element-specific resonant anomalous X-ray reflectivity with a sub-angstrom resolution. The experimental solutions were prepared using 1-10 mmol/kg metal nitrates with or without 100 mg/kg Elliott Soil Fulvic Acid II or Suwannee River Fulvic Acid from the International Humic Substances Society at pH 2-5.5. Reflectivity data were measured at the Advanced Photon Source, Argonne National Laboratory. In the absence of FA, the results show a complex picture in which there are three distinct adsorbed species that coexist at the interface: classical inner- and outer-sphere complexes plus a third OS fraction that is more broadly distributed at heights farther from the surface than the other species. Systematic trends in cation adsorption show that these three species are correlated and that their partitioning can be explained by thermodynamic equilibrium among these three species which is controlled mainly by cation hydration energy. The presence of dissolved FA modifies heavy metal uptake by two different mechanisms: it can form complexes with metal cations in solution and adsorb on muscovite as metal-organic complexes when the metal has a relatively high affinity for organic matter. In this case, the adsorbed metal cation shows a characteristic broad distribution within the entire film, resulting in formation of a more electron-dense and thicker organic film on muscovite compared to that without metals. Metals with lower organophilicity show that the enhanced metal uptake occurs mainly within the outer portion of the FA film, suggesting that the sorbed FA molecules have a preferred arrangement and express their metal-binding functional groups toward the solution. Conversely, for metal cations with larger hydration strength, little change in the amounts and distribution of metal cations was observed with adsorbed FA at the interface. These results indicate that cation hydration and organic complexation have opposing effects on heavy metal uptake on muscovite. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Geosciences Research Program, and the National Science Foundation, Geobiology and Low-Temperature Geochemistry Program.

Lee, S.; Fenter, P.; Park, C.; Sturchio, N. C.; Nagy, K.

2009-12-01

178

Substrate inhibition of acetylcholinesterase: residues affecting signal transduction from the surface to the catalytic center.  

PubMed Central

Amino acids located within and around the 'active site gorge' of human acetylcholinesterase (AChE) were substituted. Replacement of W86 yielded inactive enzyme molecules, consistent with its proposed involvement in binding of the choline moiety in the active center. A decrease in affinity to propidium and a concomitant loss of substrate inhibition was observed in D74G, D74N, D74K and W286A mutants, supporting the idea that the site for substrate inhibition and the peripheral anionic site overlap. Mutations of amino acids neighboring the active center (E202, Y337 and F338) resulted in a decrease in the catalytic and the apparent bimolecular rate constants. A decrease in affinity to edrophonium was observed in D74, E202, Y337 and to a lesser extent in F338 and Y341 mutants. E202, Y337 and Y341 mutants were not inhibited efficiently by high substrate concentrations. We propose that binding of acetylcholine, on the surface of AChE, may trigger sequence of conformational changes extending from the peripheral anionic site through W286 to D74, at the entrance of the 'gorge', and down to the catalytic center (through Y341 to F338 and Y337). These changes, especially in Y337, could block the entrance/exit of the catalytic center and reduce the catalytic efficiency of AChE. Images

Shafferman, A; Velan, B; Ordentlich, A; Kronman, C; Grosfeld, H; Leitner, M; Flashner, Y; Cohen, S; Barak, D; Ariel, N

1992-01-01

179

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

2009-03-01

180

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

181

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

182

Duox maturation factors form cell surface complexes with Duox affecting the specificity of reactive oxygen species generation  

PubMed Central

Dual oxidases (Duox1 and Duox2) are plasma membrane-targeted hydrogen peroxide generators that support extracellular hemoperoxidases. Duox activator 2 (Duoxa2), initially described as an endoplasmic reticulum resident protein, functions as a maturation factor needed to deliver active Duox2 to the cell surface. However, less is known about the Duox1/Duoxa1 homologues. We identified four alternatively spliced Duoxa1 variants and explored their roles in Duox subcellular targeting and reconstitution. Duox1 and Duox2 are functionally rescued by Duoxa2 or the Duoxa1 variants that contain the third coding exon. All active maturation factors are cotransported to the cell surface when coexpressed with either Duox1 or Duox2, consistent with detection of endogenous Duoxa1 on apical plasma membranes of the airway epithelium. In contrast, the Duoxa proteins are retained in the endoplasmic reticulum when expressed without Duox. Duox1/Duoxa1? and Duox2/Duoxa2 pairs produce the highest levels of hydrogen peroxide, as they undergo Golgi-based carbohydrate modifications and form stable cell surface complexes. Cross-functioning pairs that do not form stable complexes produce less hydrogen peroxide and leak superoxide. These findings suggest Duox activators not only promote Duox maturation, but they function as part of the hydrogen peroxide-generating enzyme.—Morand, S., Ueyama, T., Tsujibe, S., Saito, N., Korzeniowska, A., Leto, T. L. Duox maturation factors form cell surface complexes with Duox affecting the specificity of reactive oxygen species generation.

Morand, Stanislas; Ueyama, Takehiko; Tsujibe, Satoshi; Saito, Naoaki; Korzeniowska, Agnieszka; Leto, Thomas L.

2009-01-01

183

Leaf surface chemicals fromNicotiana affecting germination ofPeronospora tabacina (adam) sporangia.  

PubMed

A bioassay was used to evaluate the effects of cuticular leaf components, isolated fromN. tabacum, N. glutinosa (accessions 24 and 24a), and 23other Nicotiana species, on germinationof P. tabacina (blue mold). The leaf surface compounds included?- and?-4,8,13,-duvatriene-l,3-diols (DVT-diols), (13-E)-labda-13-ene-8?-,15-diol (labdenediol), (12-Z)-labda-12,14-diene-8?-ol (cis-abienol), (13-R)-labda-8,14-diene-13-ol (manool), 2-hydroxymanool, a mixture of (13-R)-labda-14-ene-8?,13-diol (sclareol), and (13-S)-labda-14-ene-8?,13-diol (episclareol), and various glucose and/or sucrose ester isolates. The above in acetone were applied onto leaf disks of the blue moldsusceptibleN. tabacum cv. TI 1406, which was then inoculated with blue mold sporangia. Estimated IC50 values (inhibitory concentration) were 3.0?g/cm(2) for?-DVT-diol, 2.9?/cm(2) for?-DVT-diol, 0.4?g/cm(2) for labdenediol and 4.7?g/cm(2) for the sclareol mixture. Manool, 2-hydroxymanool, andcis-abienol at application rates up to 30?g/cm(2) had little or no effect on sporangium germination. Glucose and/or sucrose ester isolates from the cuticular leaf extracts of 23Nicotiana species and three different fractions fromN. bigelovii were also evaluated for antimicrobial activity at a concentration of 30?g/cm(2). Germination was inhibited by >20% when exposed to sugar esters isolated fromN. acuminata, N. benthamiana, N. attenuata, N. clevelandii, andN. miersii, and accessions 10 and 12 ofN. bigelovii. These results imply that a number of compounds may influence resistance to blue mold in tobacco. PMID:24254279

Kennedy, B S; Nielsen, M T; Severson, R F; Sisson, V A; Stephenson, M K; Jackson, D M

1992-09-01

184

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

185

SPHOTOM - Package for an Automatic Multicolour Photometry  

NASA Astrophysics Data System (ADS)

We present basic information about package SPHOTOM for an automatic multicolour photometry. This package is in development for the creation of a photometric pipe-line, which we plan to use in the near future with our new instruments. It could operate in two independent modes, (i) GUI mode, in which the user can select images and control functions of package through interface and (ii) command line mode, in which all processes are controlled using a main parameter file. SPHOTOM is developed as a universal package for Linux based systems with easy implementation for different observatories. The photometric part of the package is based on the Sextractor code, which allows us to detect all objects on the images and perform their photometry with different apertures. We can also perform astrometric solutions for all images for a correct cross-identification of the stars on the images. The result is a catalogue of all objects with their instrumental photometric measurements which are consequently used for a differential magnitudes calculations with one or more comparison stars, transformations to an international system, and determinations of colour indices.

Parimucha, Š.; Va?ko, M.; Mikloš, P.

2012-04-01

186

IC 4651 uvby photometry (Meibom, 2000)  

NASA Astrophysics Data System (ADS)

New accurate CCD photometry in the u, v, b and y bands of the Stroemgren system filters has been obtained for 17640 stars to approximately. V=20mag in a approximately 21' x 21' field centered on the intermediate-age open cluster IC 4651. The observations was obtained with the Danish 1.5-m telescope at the European Southern Observatory, La Silla, Chile. Table 1 contains information about the Date, Night, Filter, Exposure time, Airmass, CCD rotation angle, and RA- , DE-offsets for all 89 frames. Table 2 gives cross-references between the MEI-system (this paper) and the Lindoff (1972A&AS....7..231L, IC 4651 NNN), Eggen (1971ApJ...166...87E, Cl* IC 4651 Egg NN), Anthony-Twarog & Twarog (1987AJ.....94.1222A, Cl* IC 4651 AT 1-NNN, Cl* IC 4651 AT 2-NN), and Anthony-Twarog et al. (1988AJ.....95.1453A, Cl* IC 4651 AMC I-NNN, Cl* IC 4651 AMC NNNN) identification numbers. Table 3 is the final catalogue of the new Stroemgren uvby photometry, ordered by MEI identification number. For each star, it gives the MEI number, Global CCD x- and y-coordinates, J2000 coordinates , the new y, b, v, and u magnitudes on the standard system, number of detections of the individual stars, and their mean errors. (3 data files).

Meibom, S.

2000-08-01

187

Enteric YaiW Is a Surface-Exposed Outer Membrane Lipoprotein That Affects Sensitivity to an Antimicrobial Peptide  

PubMed Central

yaiW is a previously uncharacterized gene found in enteric bacteria that is of particular interest because it is located adjacent to the sbmA gene, whose bacA ortholog is required for Sinorhizobium meliloti symbiosis and Brucella abortus pathogenesis. We show that yaiW is cotranscribed with sbmA in Escherichia coli and Salmonella enterica serovar Typhi and Typhimurium strains. We present evidence that the YaiW is a palmitate-modified surface exposed outer membrane lipoprotein. Since BacA function affects the very-long-chain fatty acid (VLCFA) modification of S. meliloti and B. abortus lipid A, we tested whether SbmA function might affect either the fatty acid modification of the YaiW lipoprotein or the fatty acid modification of enteric lipid A but found that it did not. Interestingly, we did observe that E. coli SbmA suppresses deficiencies in the VLCFA modification of the lipopolysaccharide of an S. meliloti bacA mutant despite the absence of VLCFA in E. coli. Finally, we found that both YaiW and SbmA positively affect the uptake of proline-rich Bac7 peptides, suggesting a possible connection between their cellular functions.

Arnold, Markus F. F.; Caro-Hernandez, Paola; Tan, Karen; Runti, Giulia; Wehmeier, Silvia; Scocchi, Marco; Doerrler, William T.; Ferguson, Gail P.

2014-01-01

188

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

189

DOPHOT, a CCD photometry program: Description and tests  

Microsoft Academic Search

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

Paul L. Schechter; Mario Mateo; Abhijit Saha

1993-01-01

190

UBVRI photometry of southern T Tauri stars (Batalha+ 1998)  

NASA Astrophysics Data System (ADS)

We present full tables of the photoelectric photometry of T Tauri Stars observed in the 0.5m telescope at Laboratorio Nacional de Astronomia (Brazil). The photometry was performed with the instrument FOTRAP (Jablonski et al., 1994PASP..106.1172J, see text). For a description of the UBVRI photometric system, see e.g. (2 data files).

Batalha, C. C.; Quast, G. R.; Torres, C. A. O.; Pereira, P. C. R.; Terra, M. A. O.; Jablonski, F.; Schiavon, R. P.; Sartori, M. J.

1997-11-01

191

Mg2+ binds to the surface of thymidylate synthase and affects hydride transfer at the interior active site  

PubMed Central

Thymidylate synthase (TSase) produces the sole intracellular de novo source of thymidine (i.e. the DNA base T) and thus is a common target for antibiotic and anticancer drugs. Mg2+ has been reported to affect TSase activity, but the mechanism of this interaction has not been investigated. Here we show that Mg2+ binds to the surface of Escherichia coli TSase and affects the kinetics of hydride transfer at the interior active site (16 Å away). Examination of the crystal structures identifies a Mg2+ near the glutamyl moiety of the folate cofactor, providing the first structural evidence for Mg2+ binding to TSase. The kinetics and NMR relaxation experiments suggest that the weak binding of Mg2+ to the protein surface stabilizes the closed conformation of the ternary enzyme complex and reduces the entropy of activation on the hydride transfer step. Mg2+ accelerates the hydride transfer by ca. 7-fold but does not affect the magnitude or temperature-dependence of the intrinsic kinetic isotope effect. These results suggest that Mg2+ facilitates the protein motions that bring the hydride donor and acceptor together, but it does not change the tunneling ready state of the hydride transfer. These findings highlight how variations in cellular Mg2+ concentration can modulate enzyme activity through long-range interactions in the protein, rather than binding at the active site. The interaction of Mg2+ with the glutamyl-tail of the folate cofactor and nonconserved residues of bacterial TSase may assist in designing antifolates with poly-glutamyl substitutes as species-specific antibiotic drugs.

Wang, Zhen; Sapienza, Paul J.; Abeysinghe, Thelma; Luzum, Calvin; Lee, Andrew L.; Finer-Moore, Janet S.; Stroud, Robert M.; Kohen, Amnon

2013-01-01

192

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

NASA Astrophysics Data System (ADS)

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

Zimmermann, Iris; Fleige, Heiner; Horn, Rainer

2014-05-01

193

Impact of Demographics and Military Factors Affecting Retention Rates of Female and Male Officers in the Surface Warfare and Restricted Line Communities.  

National Technical Information Service (NTIS)

This study analyzes factors that affect the retention of male and female officers, with specific emphasis on the surface warfare and restricted line communities. Specifically, the research examines whether family influence, dependent status, accession sou...

C. R. Taylor

2005-01-01

194

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

NSDL National Science Digital Library

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

195

Photometry of small asteroids and cometary cores  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

196

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

197

UBVIc photometry of NGC 4852 (Carraro+, 2005)  

NASA Astrophysics Data System (ADS)

We present wide-field deep UBVIc photometry for the previously unstudied open cluster NGC 4852 down to a limiting magnitude Ic~24, obtained from observations taken with the Wide Field Imager camera on-board the MPG/ESO 2.2m telescope at La Silla (ESO, Chile), in the photometric night of July 7, 2002. These data are used to obtain the first estimate of the cluster basic parameters, to study the cluster spatial extension by means of star counts, and to derive the Luminosity (LF) and Mass Functions (MF). The cluster radius turns out to be 5.0+/-1.0arcmin. The cluster emerges clearly from the field down to V=20mag. At fainter magnitudes, it is completely confused with the general Galactic disk field. The stars inside this region define a young open cluster (200 million years old) 1.1kpc far from the Sun (m-M=11.60, E(B-V)=0.45). The Present Day Mass Functions (PDMF) from the V photometry is one of the most extended in mass obtained to date, and can be represented as a power-law with a slope alpha=2.3+/-0.3 and (the Salpeter MF in this notation has a slope alpha=2.35), in the mass range 3.2<=m/m?<=0.6. Below this mass, the MF cannot be considered as representative of the cluster MF, as the cluster merges with the field and therefore the MF is the result of the combined effect of strong irregularities in the stellar background and interaction of the cluster with the dense Galactic field. The cluster total mass at the limiting magnitude results to be 2570+/-210M?. (1 data file).

Carraro, G.; Baume, G.; Piotto, G.; Mendez, R. A.; Schrnidtobreik, L.

2005-03-01

198

Spots, Eclipses, and Pulsation: The Interplay of Photometry and Optical Interferometric Imaging  

NASA Astrophysics Data System (ADS)

Present optical/IR interferometers like CHARA are not only capable of probing the environment surrounding stars, but also resolving surface details on the stars themselves. Because of this, interferometers can produce results on the classical topics of photometry: namely pulsation, eclipses, and star spots. In this talk I discuss these three common areas, and how interferometry and photometry can be used in conjunction to yield superior results. This research involves Georgia State University's Center for High Angular Resolution Astronomy (CHARA) in collaboration with the University of Michigan. It is supported in part by AAVSO, the National Science Foundation grant 10-16678 and the bequest of William Hershel Womble in support of astronomy at the University of Denver.

Kloppenborg, Brian K.

2011-05-01

199

Surface charges of the membrane crucially affect regulation of Na,K-ATPase by phospholemman (FXYD1).  

PubMed

The human ?1/His10-?1 isoform of Na,K-ATPase has been reconstituted as a complex with and without FXYD1 into proteoliposomes of various lipid compositions in order to study the effect of the regulatory subunit on the half-saturating Na? concentration (K(½)) of Na? ions for activation of the ion pump. It has been shown that the fraction of negatively charged lipid in the bilayer crucially affects the regulatory properties. At low concentrations of the negatively charged lipid DOPS (<10 %), FXYD1 increases K(½) of Na? ions for activation of the ion pump. Phosphorylation of FXYD1 by protein kinase A at Ser68 abrogates this effect. Conversely, for proteoliposomes made with high concentrations of DOPS (>10 %), little or no effect of FXYD1 on the K(½) of Na? ions is observed. Depending on ionic strength and lipid composition of the proteoliposomes, FXYD1 can alter the K(½) of Na? ions by up to twofold. We propose possible molecular mechanisms to explain the regulatory effects of FXYD1 and the influence of charged lipid and protein phosphorylation. In particular, the positively charged C-terminal helix of FXYD1 appears to be highly mobile and may interact with the cytoplasmic N domain of the ?-subunit, the interaction being strongly affected by phosphorylation at Ser68 and the surface charge of the membrane. PMID:24105627

Cirri, Erica; Kirchner, Corinna; Becker, Simon; Katz, Adriana; Karlish, Steven J; Apell, Hans-Jürgen

2013-12-01

200

Cell surface fucosylation does not affect development of colon tumors in mice with germline Smad3 mutation  

PubMed Central

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 lectin staining, fucosyltransferase gene northern blot analysis, and a cross of mutant mice with Fut2 and Smad3 germline mutations were performed. Results: Spontaneous colorectal tumors from Smad3 (-/-) homozygous null mice were found to express ?(1,2)fucosylated glycans in an abnormal pattern compared to adjacent nonneoplastic colon. Northern blot analysis of ?(1,2)fucosyltransferase genes Fut1 and Fut2 revealed that Fut2, but not Fut1, steady-state mRNA levels were significantly increased in tumors relative to adjacent normal colonic mucosa. Mutant mice with a Fut2-inactivating germline mutation were crossed with Smad3 targeted mice. In Smad3 (-/-)/Fut2 (-/-) double knock-out mice, UEA-I lectin staining was eliminated from colon and colon tumors, however, the number and size of tumors present by 24 weeks of age did not vary regardless of the Fut2 genotype. Conclusions: In this model of colorectal cancer, cell surface ?(1,2)fucosylation does not affect development of colon tumors.

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

2006-01-01

201

The Potential of Multicolor Photometry for Pulsating Subdwarf B Stars  

NASA Astrophysics Data System (ADS)

We investigate the potential of multicolor photometry for partial mode identification in both long- and short-period variable subdwarf B stars. The technique presented is based on the fact that the frequency dependence of an oscillation's amplitude and phase bears the signature of the mode's degree index l, among other things. Unknown contributing factors can be eliminated through the evaluation of the amplitude ratios and phase differences arising from the brightness variation in different wavebands, theoretically enabling the inference of the degree index from observations in two or more bandpasses. Employing a designated model atmosphere code, we calculate the brightness variation expected across the visible disk during a pulsation cycle in terms of temperature, radius, and surface gravity perturbations to the emergent flux for representative EC 14026 and PG 1716 star models. Nonadiabatic effects are considered in detail and found to be significant from nonadiabatic pulsation calculations applied to our state-of-the-art models of subdwarf B stars. Our results indicate that the brightness variations observed in subdwarf B stars are caused primarily by changes in temperature and radius, with surface gravity perturbations playing a small role. For PG 1716 stars, temperature effects dominate in the limit of long periods with the result that the oscillatory amplitudes and phases lose their period dependence and nonadiabatic effects become unimportant. Outside this regime, however, their values are strongly influenced by both factors. We find that the phase shifts between brightness variations in different wavebands are generally small but may lie above the experimental detection threshold in certain cases. The prospect of mode discrimination seems much more promising on the basis of the corresponding amplitude ratios. While in EC 14026 stars the amplitude ratios predicted are very similar for modes with l=0, 1, or 2, they are well separated from those of modes with l=3, l=5, and l=4 or 6, each of which form a distinct group. For the case of the PG 1716 stars it should be possible to discriminate between modes with l=1, 2, 4, or 6 and those of degree indices l=3 and l=5. Identifying modes within a given group is challenging for both types of pulsator and requires multicolor photometry of extremely high quality. Nevertheless, we demonstrate that it is feasible using the example of the largest amplitude peak detected for the fast pulsator KPD 2109+4401 by Jeffery et al. Predicted color-amplitude ratios for a series of representative EC 14026 and PG 1716 stars are available upon request. Interested collaborators please contact S. K. Randall or G. Fontaine.

Randall, S. K.; Fontaine, G.; Brassard, P.; Bergeron, P.

2005-12-01

202

The TAOS Project: High-Speed Crowded Field Aperture Photometry  

NASA Astrophysics Data System (ADS)

We have devised an aperture photometry pipeline for data reduction of image data from the Taiwanese-American Occultation Survey (TAOS). The photometry pipeline has high computational performance, and is capable of real-time photometric reduction of images containing up to 1000 stars, within the sampling rate of 5 Hz. The pipeline is optimized for both speed and signal-to-noise performance, and in the latter category it performs nearly as well as DAOPHOT. This paper provides a detailed description of the TAOS aperture photometry pipeline.

Zhang, Z.-W.; Kim, D.-W.; Wang, J.-H.; Lehner, M. J.; Chen, W. P.; Byun, Y.-I.; Alcock, C.; Axelrod, T.; Bianco, F. B.; Coehlo, N. K.; Cook, K. H.; Dave, R.; de Pater, I.; Giammarco, J.; King, S.-K.; Lee, T.; Lin, H.-C.; Marshall, S. L.; Porrata, R.; Protopapas, P.; Rice, J. A.; Schwamb, M. E.; Wang, S.-Y.; Wen, C.-Y.

2009-12-01

203

Long-term photometry of Variables IV (Sterken+, 1995)  

NASA Astrophysics Data System (ADS)

This is the fourth catalogue of photometric data in the Stroemgren system obtained during the period June 18, 1992 - August 23, 1994 in the framework of the Long-Term Photometry of Variables (LTPV) program at the European Southern Observatory. Since our goal is not absolute (all-sky) photometry, the observations should be used for differential photometry only. The mean values of the r.m.s. deviations of the differential measurements of comparison stars are around (from Table 3 of paper) ------------------------------ y b-y m1 c1 ------------------------------ 0.005 0.002 0.004 0.007 ------------------------------ (2 data files).

Sterken, C.; Manfroid, J.; Beele, D.; de Koff, S.; Eggenkamp, I. M. M. G.; Goecking, K.; Jorissen, A.; Kaufer, A.; Kuss, C.; Schoenmakers, A. P.; Still, J. M.; van Loon, J.; Vink, J.; Vrielmann, S.; Waelde, E.

1996-10-01

204

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

205

CCD Photometry of Seven Asteroids at the Belgrade Astronomical Observatory  

NASA Astrophysics Data System (ADS)

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

Benishek, Vladimir

2008-03-01

206

CCD-Photometry of Comets at Large Heliocentric Distances.  

National Technical Information Service (NTIS)

CCD imaging and time series photometry are used to determine the state of activity, nuclear properties and eventually the rotational motion of cometary nuclei. Cometary activity at large heliocentric distances and mantle evolution are not yet fully unders...

B. E. A. Mueller

1992-01-01

207

Detection of Extrasolar Planets by Transit Photometry  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

208

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

209

Accuracy of stellar parameters determined from multicolor photometry  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

210

BRITE-Constellation: Nanosatellites for Precision Photometry of Bright Stars  

NASA Astrophysics Data System (ADS)

BRITE-Constellation (where BRITE stands for BRIght Target Explorer) is an international nanosatellite mission to monitor photometrically, in two colours, the brightness and temperature variations of stars generally brighter than mag(V) ? 4 with precision and time coverage not possible from the ground. The current mission design consists of six nanosats (hence Constellation): two from Austria, two from Canada, and two from Poland. Each 7 kg nanosat carries an optical telescope of aperture 3 cm feeding an uncooled CCD. One instrument in each pair is equipped with a blue filter; the other with a red filter. Each BRITE instrument has a wide field of view (?24°), so up to about 15 bright stars can be observed simultaneously, sampled in 32 × 32 pixels sub-rasters. Photometry of additional fainter targets, with reduced precision but thorough time sampling, will be possible through onboard data processing. The BRITE sample is dominated by the most intrinsically luminous stars: massive stars seen at all evolutionary stages, and evolved medium-mass stars at the very end of their nuclear burning phases. The goals of BRITE-Constellation are to (1) measure p- and g-mode pulsations to probe the interiors and ages of stars through asteroseismology; (2) look for varying spots on the stars surfaces carried across the stellar disks by rotation, which are the sources of co-rotating interaction regions in the winds of the most luminous stars, probably arising from magnetic subsurface convection; and (3) search for planetary transits.

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

2014-06-01

211

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

212

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

PubMed Central

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

Tuncer, Duygu; Karaman, Emel; Firat, Esra

2013-01-01

213

Optical R band photometry of selected HBLs  

NASA Astrophysics Data System (ADS)

This paper presents the highlights of optical R band photometry of high-energy selected BL Lacertae objects performed at 70 cm meniscus type telescope of Abastumani Astrophysical Observatory, Georgia. Most of the targets exhibit long-term variability with 1-5 yr timescales and overall brightness variations with up to 2.4 stellar magnitudes. 1ES 0229+200 do not show clear long-term variability despite the removal the host galaxy contribution but some short-term bursts. The later are found at all brightness states of the targets, giving rise to an idea that the variety of hypothetic mechanisms should be responsible for such variations but the interactions between shock waves and jet inhomogeneities. No periodical variations are found. 1ES 1028+511 changes nearly periodically but there are no enough data points in order to consider this result as a credible one. Two-peak maxima in the historical light curves, indicating the existence of reverse shock waves along with the forward ones, are detected for several sources. The fact that no intra-night variations are found for the sample, is in agreement with the conclusions of some authors that high energy selected BL Lacs are intrinsically less variable than low-energy selected ones. The targets show intra-day changes being mainly in association with short-term bursts.

Kapanadze, B.

214

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

215

Recent Advances in Video Meteor Photometry  

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

216

Superoutburst Photometry of AL Comae Berenices  

NASA Astrophysics Data System (ADS)

Photometric observations obtained during the 1995 April - May superoutburst of the dwarf nova AL Comae Berenices are presented. This star shows rare, large-amplitude outbursts, the last definitely seen in 1975. During the 1995 outburst, as with that of 1961, there was a sharp, two-magnitude temporary minimum in the outburst light curve at about 28 days after maximum tight. We offer an explanation for such temporary minima involving the migration of a cooling wave within the accretion disk. V and I band CCD time-series photometry taken throughout the two-month-tong event, reveal a complex period structure with two dominant periods, one near 82 min and one near 41 min. Early in the outburst, photometric modulations of 81 and 86 min were seen and are likely to be related to superorbital modulations seen in other large outburst amplitude dwarf novae. Superhumps developed after ˜10 days and show a quasi-stable, nonphase coherent period of 82.5 min. A low-amplitude 41 min period was present throughout, also appearing not to be phase coherent. We conclude that the two dominant periods seen are of related origin and we list several possible mechanisms for their cause. Previous quiescence observations of AL Com have shown periods near 87 and 41 min.

Howell, Steve B.; De Young, James; Mattei, Janet A.; Foster, Grant; Szkody, Paula; Cannizzo, John K.; Walker, Gary; Fierce, Erik

1996-06-01

217

Multiband surface photometry of 21 BCGs (Micheva+ 2013)  

NASA Astrophysics Data System (ADS)

The data consist of optical and NIR broadband imaging (UBVRIHKs), obtained during the period 2003-2007 with ALFOSC (at the Nordic Optical Telescope, NOT, La Palma), MOSCA (NOT), and EMMI (at the European Southern Observatory New Technology Telescope, ESO NTT, La Silla) in the optical, and with NOTCAM (NOT) and SOFI (ESO NTT) in the NIR. Very deep observations are of a volume-limited sample of 21 Blue Compact Galaxies (Emission line galaxies). The images are reduced (bias correction, flatfielding, normalized, aligned, skysubtracted). Calibration to the Vega photometric system in the optical based on Landolt standard stars; in the NIR on 2MASS field stars found in each frame. Total exposure time (seconds) in each filter and galaxy is included in each FITS header as TOTALTIM. Cosmic rays have not been removed. (4 data files).

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

2013-07-01

218

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...

219

Uranian Satellites and Triton: JHK Photometry  

NASA Astrophysics Data System (ADS)

We report photometric measurements of Uranian satellites Miranda, Ariel, Umbriel, and Titania (10.4 Aug. 1995), and Neptune's satellite Triton (21.2 Sept. 1995) with the infrared camera (IRCAM) and standard J (1.13-1.42 mu m), H (1.53-1.81 mu m), and K (2.00-2.41 mu m) filters at the 3.8-m UKIRT telescope on Mauna Kea. The individual image frames are 256 x 256 pixels with an image scale of 0.286 arcsec/pixel, resulting in a 1.22 arcmin field of view. The standard star used for airmass correction and flux calibration was UKIRT FS 34 (EG141). The photometric information for the Uranian satellites was derived from 5-image mosaics created after dark frame and flat-field corrections; a circular aperture approximation based on DAOPHOT/aper-irtf (P. B. Stetson, PASP 99, 191, 1987) was used except in the case of Miranda, in which a linear fit to the strong background light gradient from the nearby image of Uranus was applied. The center of Uranus was 9.7 arcsec (measured on the images) from Miranda. Triton data were extracted from individual images (not mosaics) with an 8-arcsec aperture and a sky anulus 10-15 arcsec. The phase angle of the Uranian satellites was alpha =1.0(o) , and that of Triton was alpha =1.7(o) . The resulting magnitudes are as follows: Miranda J = 15.30 +/-.05, H = 15.14 +/-.05, K = 15.40 +/-.06; Ariel J = 12.96 +/-.04, H = 12.86 +/-.04, K = 13.04 +/-.04; Umbriel J = 13.60 +/-.04, H = 13.37 +/-.04, K = 13.44 +/-.04; Titania J = 12.58 +/-.04, H = 12.44 +/-.04, K = 12.60 +/-.04; Triton J = 12.26 +/-.04, H = 12.14 +/-.04, K = 12.31 +/-.04. Other reports of Uranian satellite photometry are: P. D. Nicholson and T. J. Jones (Icarus 42, 54, 1980), D. P. Cruikshank (Icarus 41, 246, 1980), and K. H. Baines et al. (Icarus 132, 266, 1998).

Kesten, P. R.; Davies, J. K.; Cruikshank, D. P.; Roush, T. L.

1998-09-01

220

uvby photometry of 4 CP stars (Adelman, 1997)  

NASA Astrophysics Data System (ADS)

Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope are presented for four magnetic chemically peculiar stars. Comparison with uvby photometry of Pedersen & Thomsen for HD 37776 yields an improved period of 1.538675 days. New periods of 15.0305 days and 18.065 days are found for the sharp-lined stars HR 2258 and HR 6958, respectively, rather than one of their aliases. For HR 6958 each color shows a slightly different time of maximum. Comparison of the four color photometry of 108 Aqr taken during the fall of 1995 which well covers the period shows the presence of a secondary minimum near primary maximum in u, v, and b. Comparison with published photometry indicates indicates that subtle changes in the shapes of the light curves have occurred suggesting that this star might be precessing. (5 data files).

Adelman, S. J.

1996-11-01

221

New MOST Photometry of the 55 Cancri System  

NASA Astrophysics Data System (ADS)

Since the discovery of its transiting nature, the super-Earth 55 Cnc e has become one of the most enthusiastically studied exoplanets, having been observed spectroscopically and photometrically, in the ultraviolet, optical and infrared regimes. To this rapidly growing data set, we contribute 42 days of new, nearly continuous MOST photometry of the 55 Cnc system. Our analysis of these observations together with the discovery photometry obtained in 2011 allows us to determine the planetary radius (1.990+0.084 -0.080) and orbital period (0.7365417+0.0000025 -0.0000028) of 55 Cnc e with unprecedented precision. We also followed up on the out-of-transit phase variation first observed in the 2011 photometry, and set an upper limit on the depth of the planet's secondary eclipse, leading to an upper limit on its geometric albedo of 0.6.

Dragomir, Diana; Matthews, Jaymie M.; Winn, Joshua N.; Rowe, Jason F.

2014-04-01

222

CCD Photometry of Bright Stars Using Objective Wire Mesh  

NASA Astrophysics Data System (ADS)

Obtaining accurate photometry of bright stars from the ground remains problematic due to the danger of overexposing the target and/or the lack of suitable nearby comparison stars. The century-old method of using objective wire mesh to produce multiple stellar images seems promising for the precise CCD photometry of such stars. Furthermore, our tests on ? Cep and its comparison star, differing by 5 mag, are very encouraging. Using a CCD camera and a 20 cm telescope with the objective covered by a plastic wire mesh, in poor weather conditions, we obtained differential photometry with a precision of 4.5 mmag per two minute exposure. Our technique is flexible and may be tuned to cover a range as big as 6-8 mag. We discuss the possibility of installing a wire mesh directly in the filter wheel.

Kami?ski, Krzysztof; Schwarzenberg-Czerny, Aleksander; Zgórz, Marika

2014-06-01

223

Inverse problems of NEO photometry: Imaging the NEO population  

NASA Astrophysics Data System (ADS)

Photometry is the main source of information on NEOs (and other asteroids) en masse. Surveys such as Pan-STARRS and LSST will produce colossal photometric databases that can readily be used for mapping the physical characteristics of the whole asteroid population. These datasets are efficiently enriched by any additional dense photometric or other observations. Due to their quickly changing geometries with respect to the Earth, NEOs are the subpopulation that can be mapped the fastest. I review the state of the art in the construction of physical asteroid models from sparse and/or dense photometric data (that can also be combined with other data modes). The models describe the shapes, spin states, scattering properties and surface structure of the targets, and are the solutions of inverse problems necessarily involving comprehensive mathematical analysis. I sum up what we can and cannot get from photometric data, and how all this is done in practice. I also discuss the new freely available software package for solving photometric inverse problems (soon to be released). The analysis of photometric datasets will very soon become an automated industry, resulting in tens of thousands of asteroid models, a large portion of them NEOs. The computational effort in this is considerable in both computer and human time, which means that a large portion of the targets is likely to be analyzed only once. This, again, means that we have to have a good understanding of the reliability of our models, and this is impossible without a thorough understanding of the mathematical nature of the inverse problem(s) involved. Very important concepts are the uniqueness and stability of the solution, the parameter spaces, the so-called inverse crimes in simulations and error prediction, and the domination of systematic errors over random ones.

Kaasalainen1, Mikko; Durech, Josef

2007-05-01

224

Identification and Removal of Noise Modes in Kepler Photometry  

NASA Astrophysics Data System (ADS)

We present the transiting exoearth robust reduction algorithm (TERRA) - a novel framework for identifying and removing instrumental noise in Kepler photometry. We identify instrumental noise modes by finding common trends in a large ensemble of light curves drawn from the entire Kepler field of view. Strategically, these noise modes can be optimized to reveal transits having a specified range of timescales. For Kepler target stars of low photometric noise, TERRA produces ensemble-calibrated photometry having 33 ppm rms scatter in 12 hr bins, rendering individual transits of Earth-size planets around Sun-like stars detectable as ˜3? signals.

Petigura, Erik A.; Marcy, Geoffrey W.

2012-10-01

225

Characterization of transiting exoplanets by way of differential photometry  

NASA Astrophysics Data System (ADS)

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

Cowley, Michael; Hughes, Stephen

2014-05-01

226

Monovalent cations differentially affect membrane surface properties and membrane curvature, as revealed by fluorescent probes and dynamic light scattering  

Microsoft Academic Search

The effects of monovalent cations on the interfacial electrostatic potential (?d), hydrodynamic shear boundary distance (ds), and membrane curvature were studied in large unilamellar phospholipid and galacto\\/sulfolipid liposomes containing different fractions of negatively charged lipids. The differential effects of alkali metal ions on ?d could be accurately determined at physiological surface charge densities with a surface-anchored fluorescent probe. Li+ and

Ruud Kraayenhof; Geert J. Sterk; Harro W. Wong Fong Sang; Klaas Krab; Richard M. Epand

1996-01-01

227

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

228

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

229

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

EPA Science Inventory

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

230

Proton exchange membrane and electrode surface areas as factors that affect power generation in microbial fuel cells  

Microsoft Academic Search

Power generation in microbial fuel cells (MFCs) is a function of the surface areas of the proton exchange membrane (PEM) and\\u000a the cathode relative to that of the anode. To demonstrate this, the sizes of the anode and cathode were varied in two-chambered\\u000a MFCs having PEMs with three different surface areas (A\\u000a PEM=3.5, 6.2, or 30.6 cm2). For a fixed anode

Sang-Eun Oh; Bruce E. Logan

2006-01-01

231

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

PubMed Central

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

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

2013-01-01

232

Photometry requested for three "Vestoid" Near-Earth Objects  

NASA Astrophysics Data System (ADS)

Dr. Michael David Hicks (Jet Propulsion Laboratory) contacted the AAVSO requesting precision photometry of three solar system objects in support of NASA's DAWN mission to Vesta. These "Vestoids" are near-Earth objects with reflectance spectra similar to Vesta itself, suggesting they may be fragments of that larger body. Broad-band photometry may help constrain object sizes and compositions. The objects are 1981 Midas (1973 EA), 4688 (1980 WF), and 137052 (1998 VO33). Hicks and collaborators are hoping to obtain photometry at the 0.1-magnitude level or better of all three objects during some or all of the first four months of 2011. All are fainter than 16th magnitude throughout their apparitions during this time frame. Multiple exposures will likely be required to reach the required signal to noise for most observers, and 4688 (1980 WF) will likely be beyond the capabilities of most telescopes by early March 2011. The Alert Notice includes ephemerides computed from known orbital parameters computed in intervals of five days beginning 2011 January 07 (JD 2455568). Magnitudes in the tables are V. Observations are requested using Rc filter if possible; V filter observations are also acceptable. We note that since these are solar system objects, they are not included in the AAVSO International Database. Observers are asked to communicate their photometry directly to the PI, and to email Elizabeth Waagen at AAVSO Headquarters so we know that you have participated.

Templeton, Matthew R.

2011-01-01

233

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

234

Spitzer-IRAC Photometry of M, L, and T Dwarfs  

Microsoft Academic Search

In the first year of Spitzer science operations, we have carried out a program to acquire photometry for some 80 late-M, L, and T dwarfs using the Infrared Array Camera (IRAC). We find it is the T dwarfs which stand out in IRAC colors and provide the most insight into the nature of brown dwarf atmospheres. For the T dwarfs

B. M. Patten; T. J. Henry; A. Burrows; J. R. Stauffer; D. Ragavan; J. Liebert; K. L. Luhman; J. L. Hora; T. Megeath; M. Marengo; G. G. Fazio

2004-01-01

235

Airborne Photometry of Comet Halley from 40 to 160 Microns.  

National Technical Information Service (NTIS)

Far infrared photometry of comet Halley was obtained from NASA's Kuiper Airborne Observatory. The brightness of the comet decreases by nearly a factor of two on the second day in phase with the variability observed in blue light by IUE during the same tim...

H. Campins M. Joy P. M. Harvey D. F. Lester H. B. Ellis

1986-01-01

236

BVI photometry of young stars in 10 clusters (Mayne+, 2007)  

Microsoft Academic Search

We present photometry in V, V-I and in some cases B-V for a range of star forming regions. NGC2547, NGC7160, NGC2264, Cepheus OB3b, Sigma Orionis, IC348 and h and chi Per. A full description of the data can be found at: http:\\/\\/www.astro.ex.ac.uk\\/people\\/timn\\/Catalogues (8 data files).

N. J. Mayne; T. Naylor; S. P. Littlefair; E. S. Saunders; R. D. Jeffries

2007-01-01

237

Comet Kohoutek. [proceedings - astronomical photometry/astronomical spectroscopy  

NASA Technical Reports Server (NTRS)

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

Gary, G. A. (editor)

1975-01-01

238

Far-Infrared and 'uvby' Photometry of V 1057 Cygni.  

National Technical Information Service (NTIS)

Four-color (uvby) photometry and broadband observations at 5 micrometers, 11 micrometers, and 20 micrometers are reported for V1057 Cyg (LkH alpha 190). The observations reveal a large flux excess superposed on the stellar continuum in the infrared. The c...

T. Simon N. D. Morrison S. C. Wolff D. Morrison

1972-01-01

239

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

240

Blue band photometry of Cygnus X-1. [and Fourier analysis  

NASA Technical Reports Server (NTRS)

Results of blue band photometry of HDE 226868 in the years 1972-3-4 and provisional results for 1975 are presented. A mean light curve is obtained from the first three years observations which is based on 192 nights observations. Intercomparison of the results from the different years shows that the light curve is not constant.

Walker, E. N.

1976-01-01

241

BVRI CCD Photometry of the Open Cluster IC 4996  

NASA Astrophysics Data System (ADS)

CCD observations in the BVRI system of 126 stars in the central part of the open cluster IC 4996 are presented. The precision of the photometry and the parameters of the cluster are discussed. A distance of r = 1620 pc and an age t = 9 Myr of the cluster are determined.

Vansevicius, V.; Bridzius, A.; Pucinskas, A.; Sasaki, T. Sasaki

242

1961-1999 UBV photometry of 14 variables (Oja, 2011)  

NASA Astrophysics Data System (ADS)

Photoelectric UBV photometry of the variable stars V636 Cas, alpha UMi, V440 Per, zeta Gem, UU Cnc, TYC2-880-515-1, V473 Lyr, chi Cyg, V1794 Cyg, DT Cyg, V1334 Cyg, V532 Cyg, pi Aqr, and DY Peg is reported. (15 data files).

Oja, T.

2011-11-01

243

Low Surface Brightness Galaxies.  

National Technical Information Service (NTIS)

A program to investigate the properties of low surface brightness (LSB) galaxies involving surface photometry in U, B, V, R, I, and H-alpha, HI imaging with the Westerbork Synthesis Radio Telescope (WSRT) and the very large array (VLA) and spectrophotomet...

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

1993-01-01

244

Polarimetry and photometry of the peculiar main-belt object 7968 = 133P/Elst-Pizarro  

NASA Astrophysics Data System (ADS)

Context. Photometry and polarimetry have been extensively used as a diagnostic tool for characterizing the activity of comets when they approach the Sun, the surface structure of asteroids, Kuiper-Belt objects, and, more rarely, cometary nuclei. Aims: 133P/Elst-Pizarro is an object that has been described as either an active asteroid or a cometary object in the main asteroid belt. Here we present a photometric and polarimetric study of this object in an attempt to infer additional information about its origin. Methods: With the FORS1 instrument of the ESO VLT, we have performed during the 2007 apparition of 133P/Elst-Pizarro quasi-simultaneous photometry and polarimetry of its nucleus at nine epochs in the phase angle range ~ 0° - 20°. For each observing epoch, we also combined all available frames to obtain a deep image of the object, to seek signatures of weak cometary activity. Polarimetric data were analysed by means of a novel physical interference modelling. Results: The object brightness was found to be highly variable over timescales <1 h, a result fully consistent with previous studies. Using the albedo-polarization relationships for asteroids and our photometric results, we found for our target an albedo of about 0.06-0.07 and a mean radius of about 1.6 km. Throughout the observing epochs, our deep imaging of the comet detects a tail and an anti-tail. Their temporal variations are consistent with an activity profile starting around mid May 2007 of minimum duration of four months. Our images show marginal evidence of a coma around the nucleus. The overall light scattering behaviour (photometry and polarimetry) resembles most closely that of F-type asteroids. Based on observations made with ESO Telescopes at the Paranal Observatory under programme ID 079.C-0653 (PI = Tozzi).

Bagnulo, S.; Tozzi, G. P.; Boehnhardt, H.; Vincent, J.-B.; Muinonen, K.

2010-05-01

245

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

2012-09-01

246

Membrane curvature and surface area per lipid affect the conformation and oligomeric state of HIV1 fusion peptide: A combined FTIR and MD simulation study  

Microsoft Academic Search

Fourier-transformed infrared spectroscopy (FTIR) and molecular dynamics (MD) simulation results are presented to support our hypothesis that the conformation and the oligomeric state of the HIV-1 gp41 fusion domain or fusion peptide (gp41-FP) are determined by the membrane surface area per lipid (APL), which is affected by the membrane curvature. FTIR of the gp41-FP in the Aerosol-OT (AOT) reversed micellar

Bogdan Barz; Tuck C. Wong; Ioan Kosztin

2008-01-01

247

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

Microsoft Academic Search

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

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

2003-01-01

248

In vitro lead bioaccessibility and phosphate leaching as affected by surface application of phosphoric acid in lead-contaminated soil.  

PubMed

Phosphate treatment of lead-contaminated soil may be a cost-effective remedial alternative for in situ stabilizing soil Pb and reducing Pb toxicology to human. The leaching behaviors of the P added to soil surface and the effect on subsurface Pb bioaccessibility must be addressed for this remedial technology to be acceptable. A smelter-contaminated soil containing an average of 2,670 mg Pb kg(-1), collected from the Jasper County Superfund Site located in Jasper County, Missouri, was surface treated with 10 g P kg(-1) as phosphoric acid (H(3)PO(4)). Following a simulated column leaching and 90-day treatment of field plots, respectively, bioaccessible Pb, P, and pH in soil profile were measured. Surface treatment using H(3)PO(4) effectively stabilized soil Pb and reduced leachable Pb and the bioaccessibility. Phosphate leached into deeper profile significantly lowered bioaccessible Pb in subsurface. Reduction of Pb bioaccessibility increased as a linear function of increasing soil P. Although surface H(3)PO(4) treatment resulted in an enhanced leaching of added P and may increase potential risk of surface and groundwater pollution, the P leaching under field conditions is very limited. Lime addition following the treatment may reduce the leachability of added P and further immobilize soil Pb. PMID:12399910

Yang, J; Mosby, D E; Casteel, S W; Blanchar, R W

2002-11-01

249

Photometry of southern globular clusters. V - Photographic photometry of faint stars in Omega Centauri  

NASA Astrophysics Data System (ADS)

Photographic photometry obtained by the 3.9-m Anglo-Australian Telescope of approximately 300 faint stars in the globular cluster Omega Centauri is presented. The color-magnitude diagram was obtained from prime-focus plates measured with an iris photometer and calibrated by a faint photoelectric sequence. The main sequence turn-off point on the diagram is found to lie significantly below a V magnitude of 18, which is about 3.8 mag below the horizontal branch, however the value probably does not imply an exceptionally large age for the cluster. The spread in color observed at the top of the main sequence is noted to be compatible with the spread in heavy element abundance deduced from previous studies of the evolved stars, however does not establish the existence of a primordial abundance spread and is also compatible with a negligible intrinsic scatter in color. Future studies capable of resolving the problem of primordial abundance variations and the age of the cluster are indicated.

Cannon, R. D.; Stewart, N. J.

1981-04-01

250

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

251

Phosphorylation of transitory starch by ?-glucan, water dikinase during starch turnover affects the surface properties and morphology of starch granules.  

PubMed

Glucan, water dikinase (GWD) is a key enzyme of starch metabolism but the physico-chemical properties of starches isolated from GWD-deficient plants and their implications for starch metabolism have so far not been described. Transgenic Arabidopsis thaliana plants with reduced or no GWD activity were used to investigate the properties of starch granules. In addition, using various in vitro assays, the action of recombinant GWD, ?-amylase, isoamylase and starch synthase 1 on the surface of native starch granules was analysed. The internal structure of granules isolated from GWD mutant plants is unaffected, as thermal stability, allomorph, chain length distribution and density of starch granules were similar to wild-type. However, short glucan chain residues located at the granule surface dominate in starches of transgenic plants and impede GWD activity. A similarly reduced rate of phosphorylation by GWD was also observed in potato tuber starch fractions that differ in the proportion of accessible glucan chain residues at the granule surface. A model is proposed to explain the characteristic morphology of starch granules observed in GWD transgenic plants. The model postulates that the occupancy rate of single glucan chains at the granule surface limits accessibility to starch-related enzymes. PMID:24697163

Mahlow, Sebastian; Hejazi, Mahdi; Kuhnert, Franziska; Garz, Andreas; Brust, Henrike; Baumann, Otto; Fettke, Joerg

2014-07-01

252

Stromvil Photometry: Peculiar Stars and Anomalous Reddening  

NASA Astrophysics Data System (ADS)

Possibilities of the Stromvil photometric system in identifying peculiar stars of various types are reviewed. The system can identify in the presence of interstellar reddening the following types of peculiar stars: F--G--K--M subdwarfs, G--K--M metal-deficient giants, cool carbon, barium and zirconium stars, chemically peculiar B and A stars, emission-line stars (Be, Ae/Be, WR, T Tauri, etc.), white dwarfs, a fraction of horizontal-branch stars and many types of unresolved binaries. Also, the system can identify stars affected by anomalous interstellar reddening and classify them correctly.

Straizys, V.

253

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

254

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

PubMed Central

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

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

2014-01-01

255

Heavy metal contents in surface soils along the Upper Scheldt river (Belgium) affected by historical upland disposal of dredged materials.  

PubMed

For several decades, periodical dredging of river sediments has been necessary to allow for shipping traffic on the river Scheldt. Sediments were disposed along the shores in the alluvial plain without concern for the potential presence of contaminants. The aim of this study was to survey the alluvial plains of the Upper Scheldt river in Belgium for the presence of old dredged sediment landfills, and to appraise the heavy metal contamination at these sites. Up to 82% of the areas that were affected by dredged sediment disposal was found to be polluted by at least one of the metals Cd, Cr, Zn or Pb. Concentrations of Cd, Cr and Zn were, in 10% of the cases, higher than 26, 1900 and 2800 mg/kg, respectively. Cu and Ni concentrations were of no environmental concern on any site. Trends in metal concentrations as a function of location and time were explored and discussed. The highest average concentrations of Cd, Cr, Cu, Pb and Zn were found in the most downstream quarter of the Upper Scheldt. Contents of Pb and Cu were significantly lower for sediments disposed after 1965, but no indication for improvement of the sediment quality with time was observed for Cd, Cr and Zn. The pollution levels encountered warrant for caution as most of the soils affected by historical dredged sediment disposal are currently in use for agriculture, nature development or forestry. PMID:12083701

Vandecasteele, Bart; De Vos, Bruno; Tack, Filip M G

2002-05-01

256

HIIPHOT: Automated Photometry of H II Regions  

NASA Astrophysics Data System (ADS)

HIIPHOT enables accurate photometric characterization of H II regions while permitting genuine adaptivity to irregular source morphology. It makes a first guess at the shapes of all sources through object recognition techniques; it then allows for departure from such idealized "seeds" through an iterative growing procedure and derives photometric corrections for spatially coincident diffuse emission from a low-order surface fit to the background after exclusion of all detected sources.

Thilker, David A.; Braun, Robert; Walterbos, René A. M.

2014-05-01

257

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

PubMed

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

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

2014-07-18

258

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

NSDL National Science Digital Library

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

259

Photometry of chemically peculiar stars (Adelman+ 1997)  

NASA Astrophysics Data System (ADS)

Differential Stromgren uvby photometric observations from the Four College Automated Photoelectric Telescope of four magnetic Chemically Peculiar stars are used to refine rotational periods and to define the shapes of the light curves. HR 1643 (P=2.73475d) shows large phase variability in all four magnitudes. Theta Aur (P=3.6188d) exhibits large amplitude variations with two components contributing to the minima. For 49 Cam (P=4.28679d), we probably are observing both polar regions and much of the surface. The values for HR 3724 (P=33.984d) confirm Wolff's result that the main variability is in v. (5 data files).

Adelman, S. J.

1997-02-01

260

CCD photometry of the Uranian satellites  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

261

CCD photometry of the Uranian satellites  

NASA Astrophysics Data System (ADS)

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

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

1992-10-01

262

Infrared photometry and spectrometry of Nova Aquilae 1982  

NASA Astrophysics Data System (ADS)

Photometry and 2-4 and 8-13 micron spectrometry of Nova Aquilae 1982, obtained during its dust shell phase are presented. The photometry indicates that, if dust formation ocurred in the outburst ejecta, it did so at an anomalously early stage of the outburst; alternatively the dust shell may have predated the eruption. Spectrometry at the shorter wavelengths suggests the presence of broad, weak features, whilst that in the 8-13 micron window shows strong emission from siicate grains. This indicates that, unlike the situation in previous dusty novae, the grains around Nova Aquilae formed in an oxygen-rich environment. The difference between this nova and others observed in the infrared to date may thus provide clues to differing elemental abundances in classical nova progenitors. On the other hand, this object may not have undergone a normal classical nova outburst.

Bode, M. F.; Evans, A.; Whittet, D. C. B.; Aitken, D. K.; Roche, P. F.; Whitmore, B.

1984-04-01

263

Galaxy Photometry Science Verification Tests for the Dark Energy Survey  

NASA Astrophysics Data System (ADS)

The Dark Energy Survey (DES) is an optical imaging survey that will use a new 570-megapixel camera, the Dark Energy Camera (DECam), to image 5000 square degrees of the Southern Galactic Cap in the 5 filters grizY. The primary DES science goal is to constrain dark energy cosmological parameters using the 4 complementary science probes of galaxy clusters, weak lensing, large scale structure, and supernove. Commissioning of DECam has begun Sept. 2012, and DES science verification and the beginning of first season of operations are scheduled for late 2012. Here we report on tests of galaxy photometry undertaken as part of DES science verification. In particular, we will describe the results of measurements of galaxy detection completess and purity, checks of the fidelity of estimated photometric errors, and tests of the homogeneity of photometry across the very large, 2-degree diameter DECam focal plane.

Lin, Huan; Soares-Santos, M.; Diehl, H.; Dark Energy Survey Collaboration

2013-01-01

264

UBVRI photometry of the recurrent nova T coronae borealis  

NASA Astrophysics Data System (ADS)

Differential UBVRI photometry of this bright recurrent nova at three different observatories in 1981, 1982, and 1983 reveals variability on three different timescales. By Fourier analysis the amplitude of the ellipticity effect at UBVRI is determined and used to find the prolateness coefficient z = 0.14 + or - 0.01. Times of minimum light equated with times of conjunction and combined with previously published times yield 227.67 d + or - 0.02 d for a refined orbital period. Continuous photometry on one night confirms short-term variability reported earlier. Residuals from the Fourier fits reveal an additional variability with a period of about 55 days and an amplitude that in 1983 was 0.35 mag in V, 0.5 mag in B, and 0.8 mag in U. It is concluded that the gM3 primary is probably a semiregular red variable.

Lines, Helen C.; Lines, Richard D.; McFaul, Thomas G.

1988-05-01

265

Photometry on Metal-Poor Stars with HST Parallaxes  

NASA Astrophysics Data System (ADS)

Stellar evolution models and isochrones of metal-poor stars are widely used in astrophysics. However, there are few observational tests of the validity of these models below metallicities of [Fe/H] = -1.5. To remedy this situation, HST has determined parallaxes for 9 metal-poor main sequence stars. Here, we present new ground-based photometry of these stars. The observations were obtained at MDM observatory in March of 2012 over the course of five nights. Our photometry is compared to literature values and combined with parallax results to obtain absolute magnitudes for these stars. The locations of the stars on a color-magnitude diagram are compared to theoretical models.

Joyce, Meridith; Chaboyer, Brian C.; Feiden, Gregory A.; Matthews, Morgan; Benedict, G. Fritz; McArthur, Barbara; Harrison, Thomas E.; McWilliam, Andrew; Nelan, Edmund P.; Patterson, Richard J.; Sarajedini, Ata

2014-06-01

266

BV photometry of two evolved variables in NGC 188  

NASA Astrophysics Data System (ADS)

CCD BV photometry, is presented of two NGC 188 variables located on the cluster color-magnitude diagram between red-giant-branch and blue stragglers region. Variable V8 has a sine-like light curve with an amplitude of variations about 0.15 mag. The period of variation is 4.03 d or 8.06 d. Different sets of photometry collected between 1985 and 1989 are compared. There is no evidence for changes of the mean brightness level or amplitude of light variations. Variable V11, probably being an eclipsing binary, exhibited small (total range about 0.03 mag), but clearly real, changes of brightness during 13 consecutive nights. V11 belongs to RS CVn-type variables.

Mazur, Beata; Kaluzny, Janusz

267

Long-term photometry of Variables I. (Manfroid+ 1991)  

NASA Astrophysics Data System (ADS)

This is the first catalogue of photometric data in the Stroemgren system obtained during the period October 1982 - September 1986. Full description can be found in ESO report SP 8. Since our goal is not absolute (all-sky) photometry, the observations should be used for differential photometry only. The mean values of the r.m.s. deviations of the differential measurements of comparison stars are around (from Table 5 of paper) ------------------------------------ System y b-y m1 c1 ------------------------------------ 1 0.0109 0.0088 0.0133 0.0136 4 0.0068 0.0057 0.0079 0.0118 5 0.0087 0.0070 0.0114 0.0114 6 0.0090 0.0078 0.0126 0.0132 7 0.0071 0.0033 0.0041 0.0065 ------------------------------------ (2 data files).

Manfroid, J.; Sterken, C.; Bruch, A.; Burger, M.; de Groot, M.; Duerbeck, H. W.; Duemmler, R.; Figer, A.; Hageman, T.; Hensberge, H.; Jorissen, A.; Madejsky, R.; Mandel, H.; Ott, H. A.; Reitermann, A.; Schulte-Ladbeck, R. E.; Stahl, O.; Steenman, H.; Vander Linden, D.; Zickgraf, F. J.

1995-11-01

268

Time-resolved CCD photometry of an ensemble of stars  

NASA Astrophysics Data System (ADS)

A technique for obtaining CCD photometry of a large ensemble of stars, with precision limited by atmospheric scintillation and photon statistics is presented. Under bright-sky conditions with a 0.9-m telescope, a precision of about 0.0015 mag relative to an ensemble average standard was obtained for 12th-13th mag stars in M 67 with exposure times of 1 min. The increase in noise level due to variable cirrus clouds is minimal. Effective noise levels for the detection of coherent oscillations with periods of 5-20 min could thus be reduced to about 30 micromag over ten nights of observing for stars of this brightness. A much larger ensemble of faint stars could be followed at lower precision with sky background and photon statistics as dominant error sources. Four probable-cluster DA white dwarfs were detected in the old galactic cluster M 67, using B, V calibration photometry.

Gilliland, Ronald L.; Brown, Timothy M.

1988-06-01

269

High-speed multicolour photometry with CMOS cameras  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

270

16 and 24-Micron Photometry of Transiting Extrasolar Planets  

NASA Astrophysics Data System (ADS)

We have recently used Spitzer MIPS-24 to detect light from the transiting extrasolar planet HD 209458b during its secondary eclipse. Previously, there had been no direct detection of light from an extrasolar planet. Our calculated brightness temperature constrains models of this planet's thermal emission. We now propose additional eclipse photometry of HD 209458b using the IRS blue peak-up array and MIPS-24 to provide a brightness temperature at 16 microns, reduce the errors on our 24-micron measurement, search for variability due to atmospheric dynamics, investigate the puzzlingly large radius of this planet, and possibly derive the day/night temperature contrast. We also propose eclipse photometry of the second-brightest transiting planet, TrES-1b, in the IRS blue peak-up array, with similar goals. These pioneering measurements of extrasolar planetary fluxes will constrain the many competing radiative, chemical, and dynamical models of these planets' atmospheres.

Harrington, Joseph; Cho, James; Deming, Drake; Hansen, Brad; Menou, Kristen; Richardson, Jeremy; Seager, Sara

2005-06-01

271

BV photographic and CCD photometry of IC 4651  

NASA Astrophysics Data System (ADS)

A BV photometric survey in IC 4651 based on photographic and CCD material calibrated with photoelectric photometry from Eggen (1971) and Anthony-Twarog and Twarog (1987) has been completed. The color-magnitude diagram is consistent with an age of 2.4 + or - 0.3 x 10 to the 9th yr derived by comparison with the isochrones of VandenBerg (1985) if the apparent distance modulus and reddening derived from uvby photometry in Anthony-Twarog and Twarog (1987) are employed. While evidence is found of a hook in the upper main sequence, no evidence is found of a significantly bifurcated main sequence for this cluster, although it is similar in age to NGC 752 and NGC 3680, where this phenomenon has been noted. Finally, the survey has not resolved the apparent deficit of main-sequence stars fainter than V = 14.5 noted in Anthony-Twarog and Twarog (1987).

Anthony-Twarog, Barbara J.; Mukherjee, Krishna; Twarog, Bruce A.; Caldwell, Nelson

1988-05-01

272

Ultraviolet photometry of OB associations in M31  

NASA Technical Reports Server (NTRS)

The study obtains near-UV and FUV magnitudes for 76 massive stars in 24 OB associations in the central and southern portions of M31 from images obtained by the Ultraviolet Imaging Telescope (UIT) during the Astro 1 spacelab mission. A comparison is made with the previous UIT photometry of 30 stars in the giant association NGC 206. Extinctions are estimated from the relation between E(B - V) and the distance from the center of M31 derived by Hodge and Lee (1988) from topical CCD stellar photometry. From evolutionary models, lower limits to the maximum stellar mass are estimated at about 60-100 solar masses in NGC 206, A29, A61, A63, A130, and A132. For other associations, the limits are in the range of about 20-55 solar masses.

Hill, Jesse K.; Isensee, Joan E.; Bohlin, Ralph C.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P.

1993-01-01

273

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

PubMed Central

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

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

2010-01-01

274

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

PubMed

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

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

2014-09-15

275

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

NASA Astrophysics Data System (ADS)

As the solar wind is absorbed on the lunar dayside, a clear and obvious plasma void is created in the anti-solar direction that extends many lunar radii behind the Moon. Plasma adjacent to this void will expand into the depleted region and this process is modeled here using a particle-in-cell code. It is found that thermal electrons will diffuse into the void ahead of the ions, creating a break in plasma quasi-neutrality. In essence, immediately trailing behind the lunar terminator/polar regions, there is a magnetic-field aligned E-field peaking near 400 mV/m associated with a standing double-layer, this layer consisting of fast thermal electrons (electron cloud) moving into the central void ahead of an ion-enhanced layer. We demonstrate that the surface locations that are incident with the electron cloud (just nightside of the terminator) will develop enhanced negative surface potentials due to the dominance of electron currents. Such regions of large negative potentials near the lunar poles are of interest, especially given NASA's recent announcement of a lunar outpost at the south polar Aitken Basin.

Farrell, W. M.; Stubbs, T. J.; Halekas, J. S.; Delory, G. T.; Collier, M. R.; Vondrak, R. R.; Lin, R. P.

2008-03-01

276

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

PubMed

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

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

2013-01-01

277

Mutations in Arabidopsis thaliana genes involved in the tryptophan biosynthesis pathway affect root waving on tilted agar surfaces  

NASA Technical Reports Server (NTRS)

Arabidopsis thaliana roots grow in a wavy pattern upon a slanted surface. A novel mutation in the anthranilate synthase alpha 1 (ASA1) gene, named trp5-2wvc1, and mutations in the tryptophan synthase alpha and beta 1 genes (trp3-1 and trp2-1, respectively) confer a compressed root wave phenotype on tilted agar surfaces. When trp5-2wvc1 seedlings are grown on media supplemented with anthranilate metabolites, their roots wave like wild type. Genetic and pharmacological experiments argue that the compressed root wave phenotypes of trp5-2wvc1, trp2-1 and trp3-1 seedlings are not due to reduced IAA biosynthetic potential, but rather to a deficiency in L-tryptophan (L-Trp), or in a L-Trp derivative. Although the roots of 7-day-old seedlings possess higher concentrations of free L-Trp than the shoot as a whole, trp5-2wvc1 mutants show no detectable alteration in L-Trp levels in either tissue type, suggesting that a very localized shortage of L-Trp, or of a L-Trp-derived compound, is responsible for the observed phenotype.

Rutherford, R.; Gallois, P.; Masson, P. H.

1998-01-01

278

T1C photometry of NGC7507 (Caso+, 2013)  

NASA Astrophysics Data System (ADS)

We present a catalog of point-like sources around NGC 7507, which forms the photometric database for our paper. The sources were obtained from the PSF photometry of MOSAIC images in filters R and C. The catalog contains coordinates, T1 magnitudes with uncertainties, and C-T1 colors and their uncertainties. Magnitudes and colour are corrected by absorption and reddening. (1 data file).

Caso, J. P.; Richtler, T.; Bassino, L. P.; Salinas, R.; Lane, R. R.; Romanowsky, A.

2013-07-01

279

CCD BVI photometry of 3 open clusters (Pietrukowicz+, 2006)  

NASA Astrophysics Data System (ADS)

Photometry of two fields which include three open clusters: NGC 2425, Haffner 10 and Czernik 29. For each star of the clusters: equatorial coordinates, Johnson-Cousins system magnitudes and colours with uncertainties. Instrumentation: 1.02-m f/10.0 Ritchey-Chretien + 1024x1024 CCD with a scale 0.695 arcsec/pixel at Las Campanas Observatory. Date of observations: Feb 20/21 and Feb 21/22, 1995. (2 data files).

Pietrukowicz, P.; Kaluzny, J.; Krzeminski, W.

2005-10-01

280

Spitzer IRAC Photometry of M, L, and T Dwarfs  

Microsoft Academic Search

We present the results of a program to acquire photometry for 86 late M, L, and T dwarfs using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We examine the behavior of these cool dwarfs in various color-color and color-magnitude diagrams composed of near-IR and IRAC data. The T dwarfs exhibit the most distinctive positions in these diagrams.

Brian M. Patten; John R. Stauffer; Adam Burrows; Massimo Marengo; Joseph L. Hora; Kevin L. Luhman; Sarah M. Sonnett; Todd J. Henry; Deepak Raghavan; S. Thomas Megeath; James Liebert; Giovanni G. Fazio

2006-01-01

281

Infrared Photometry of Late-M, L, and T Dwarfs  

Microsoft Academic Search

We present ZJHKL'M' photometry of a sample of 58 late M, L, and T dwarfs, most of which are identified from the Sloan Digital Sky Survey and the Two Micron All-Sky Survey. Near-infrared spectra and spectral classifications for most of this sample are presented in a companion paper by Geballe et al. We derive the luminosities of 18 dwarfs in

David A. Golimowski; Xiaohui Fan; T. R. Geballe; G. R. Knapp; J. Brinkmann; István Csabai; James E. Gunn; Suzanne L. Hawley; Todd J. Henry; Robert Hindsley; Zeljko Ivezic; Robert H. Lupton; Jeffrey R. Pier; Donald P. Schneider; J. Allyn Smith; Alan Uomoto; D. G. York

2002-01-01

282

Reconstructing Galaxy Spectral Energy Distributions from Broadband Photometry  

Microsoft Academic Search

We present a novel approach to photometric redshifts, one that merges the\\u000aadvantages of both the template fitting and empirical fitting algorithms,\\u000awithout any of their disadvantages. This technique derives a set of templates,\\u000adescribing the spectral energy distributions of galaxies, from a catalog with\\u000aboth multicolor photometry and spectroscopic redshifts. The algorithm is\\u000aessentially using the shapes of the

I. Csabai; A. J. Connolly; A. S. Szalay; T. Budavari

1999-01-01

283

High precision differential photometry of planet transits with the MMTF  

Microsoft Academic Search

We propose to use Magellan+MMTF(IMACS) to achieve some of the very highest precision ground-based, time-differential, narrow-band photometry to date on selected favorable transiting planet host stars. The proposed observations are expected to provide precise measurements of the time, duration, shape, and color of an exoplanet transit. Our primary target, CoRoT-7, is an active star hosting the first transiting super-Earth transiting

Brian L. Lee; Knicole D. Colon; Eric B. Ford; Cullen H. Blake; Suvrath Mahadevan

2010-01-01

284

High Speed Optical Photometry of LMXBs and CVs  

NASA Astrophysics Data System (ADS)

High speed photometry of several accreting binaries was obtained using the McDonald Observatory 2.1m telescope and ARGOS CCD photometer. A broad-band filter (BVR) was used in order to maximize flux and maintain a short (1-10s) integration time on faint targets. Such observations obtained over several years allow for variability study over time scales covering many orders of magnitude. Observations and analysis for several binaries are summarized.

Mason, Paul A.; Robinson, Edward L.; Gomez, Sebastian; Gonzalez, Emmanuel; Lopez, Isaac D.; Monroy, Lorena; Price, Alex

2013-02-01

285

IR photometry of ESO calibration stars (van der Bliek+ 1996)  

NASA Astrophysics Data System (ADS)

We describe the infrared (IR) photometric system for the single channel photometers at ESO, which have been used from 1983 until 1994. In addition to the broadband near infrared (NIR, 1-5?m) photometric system presented in 1991 by Bouchet et al. and Bersanelli et al., we describe a narrow-band NIR photometric system and a mid infrared (MIR, 7-20?m) photometric system. We also extend the set of NIR standard stars by Bouchet et al. towards fainter objects (K=~9). The photometric data of the standard stars in these systems were extracted from the complete IR photometric data archive of ESO, covering 10 years. The zeropoints of the NIR photometry are set by assuming that HR 3314 has a V-magnitude of 3.89, and that V-K=-0.05, J-K=-0.01, H-K=-0.01, K-L'=0.00, K-M=0.00. The zeropoints of the MIR photometry are set by assuming that the colours of? Hyi (HR 0098) and ? CenA (HR 5459) are equal to the colours of the Sun. We adopt the absolute calibration of Megessier (1995A&A...296..771M) for the NIR and we argue that this calibration can be extrapolated to 20?m, using the MIR calibrations by Rieke et al. (1985AJ.....90..900R) and Cohen et al. (1992AJ....104.1650C). The definition of the zeropoints is consistent with the absolute calibration. We obtained accurate (?=~0.02mag.) NIR photometry of about 240 standard stars and MIR photometry of about 40 standard stars (?=~0.04mag). Comparison of our NIR photometric system with other well established systems shows that there are some small colour dependencies and zeropoint offsets which are always smaller than about 0.02mag. except for the L' band. (3 data files).

van der Bliek, N. S.; Manfroid, J.; Bouchet, P.

1996-04-01

286

CCD time-resolved photometry of faint cataclysmic variables. IV  

NASA Technical Reports Server (NTRS)

Time-resolved CCD photometry in V, B, and the near-IR has been obtained, with average time-series length of 3 hours, for 15 certified or candidate cataclysmic-variable faint stars. Orbital periods are found in three of the stars, and nine others are noted to exhibit evidence leading toward confirmation of cataclysmic-variable status. The characteristics of PG 0917+342 and PG 2240+193 are as yet unclear.

Howell, Steve B.; Dobrzycka, Danuta; Szkody, Paula; Kreidl, Tobias J.

1991-01-01

287

BVRI photometry of the type Ic Hypernova SN 2002ap  

Microsoft Academic Search

The BVRI photometric observations of type-Ic SN 2002ap at maximum and during the fast-decline phase after maximum are presented. We used our BVRI photometry and published data in order to compute the magnitudes and dates of peak brightness. The absolute magnitude at maximum brightness of SN 2002ap shows that it was fainter than SN 1998bw, but similar to SN 1997ef.

L. M. Cook; E. V. Katkova; N. A. Sokolov; I. S. Guseva

2002-01-01

288

Blue-light imagery and photometry of sprites  

Microsoft Academic Search

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

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

1998-01-01

289

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

290

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

2010-10-01

291

MATPHOT algorithm for digital point spread function CCD stellar photometry  

NASA Astrophysics Data System (ADS)

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

Mighell, Kenneth J.

2002-12-01

292

Spitzer photometry of globulars in 2 galaxies (Spitler+, 2008)  

NASA Astrophysics Data System (ADS)

Catalogues are described in Spitler et al. (2008MNRAS.389.1150S) All photometry is corrected for Galactic dust extinction and are on the Vega photometric system. NGC 5128 optical photometry is from Peng et al. (2004ApJS..150..367P), as compiled in Woodley et al. (2007AJ....134..494W). Globular cluster identification numbers are from Woodley et al. (2007, Cat. J/AJ/134/494). NGC 4594 optical photometry is from Spitler et al. (2006AJ....132.1593S) updated with new aperture corrections as described in Harris et al. (2010MNRAS.401.1965H). Identification number, globular cluster half-light radii and the assumed distance modulus for the half-light radii are from Spitler et al. (2006, Cat. J/AJ/132/1593). A ultra-compact dwarf galaxy is included in this catalogue with ID="ucd" (see also Hau et al. 2009MNRAS.394L..97H). (2 data files).

Spitler, L. R.; Forbes, D. A.; Beasley, M. A.

2010-06-01

293

Transformed photometry of young stars in Cha requested  

NASA Astrophysics Data System (ADS)

Dr. Peter Abraham (Konkoly Observatory, Budapest, Hungary) requested the assistance of AAVSO observers in monitoring eight young stars in Chamaeleon in support of photometry he and his colleagues will be obtaining with the VLT/ISAAC (infrared) and Herschel Space Observatory (far-infrared) during January-February 2013. The targets are CR Cha, CT Cha, HP Cha (Glass I), VW Cha, VZ Cha, WW CHa, WX Cha, XX Cha. Calibrated, transformed VRI photometry is requested to precisely monitor changes in the optical brightness and colors of these objects. Calibration and transformation of the photometry is crucial - if all of the data are not on the same system and particularly if the colors are not transformed, it will be extremely difficult to correlate the data usefully. Previous observations indicate that the stars are highly variable. Brightness changes can be expected from a few tenths of a magnitude to up to 1-2 magnitudes on a timescale of a few days to a few weeks. Observers are asked to try to obtain one to two sets of VRI images per night. Finder charts with sequences 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.

Waagen, Elizabeth O.

2013-01-01

294

Network-scale dynamics of sediment mixtures: how do tectonics affect surface bed texture and channel slope?  

NASA Astrophysics Data System (ADS)

An alluvial channel's slope and bed texture are intimately linked. Along with fluvial discharge, these variables are the key players in setting alluvial transport rates. We know that both channel slope and mean grain size usually decrease downstream, but how sensitive are these variables to tectonic changes? Are basin concavity and downstream fining drastically disrupted during transitions from one tectonic regime to another? We explore these questions using the CHILD numerical landscape evolution model to generate alluvial networks composed of a sand and gravel mixture. The steady-state and transient patterns of both channel slope and sediment texture are investigated. The steady-state patterns in slope and sediment texture are verified independently by solving the erosion equations under equilibrium conditions, i.e. the case when the erosion rate is equal to the uplift rate across the entire landscape. The inclusion of surface texture as a free parameter (as opposed to just channel slope) leads to some surprising results. In all cases, an increase in uplift rate results in channel beds which are finer at equilibrium (for a given drainage area). Higher uplift rates imply larger equilibrium transport rates; this leads to finer channels that have a smaller critical shear stress to entrain material, and therefore more material can be transported for a given discharge (and channel slope). Changes in equilibrium slopes are less intuitive. An increase in uplift rates can cause channel slopes to increase, remain the same, or decrease, depending on model parameter values. In the surprising case in which equilibrium channel slopes decrease with increasing uplift rates, we suggest that surface texture changes more than compensate for the required increase in transport rates, causing channel slopes to decrease. These results highlight the important role of sediment grain size in determining transport rates and caution us against ignoring this important variable in fluvial networks.

Gasparini, N. M.; Bras, R. L.; Tucker, G. E.

2003-04-01

295

Reduced oxide sites and surface corrugation affecting the reactivity, thermal stability, and selectivity of supported Au-Pd bimetallic clusters on SiO2/Si(100).  

PubMed

The morphology and surface elemental composition of Au-Pd bimetallic nanoclusters are reported to be sensitive to and affected by reduced silicon defect sites and structural corrugation on SiO2/Si(100), generated by argon ion sputtering under ultrahigh vacuum (UHV) conditions. Metastable structures of the bimetallic clusters, where Au atoms are depleted from the top surface upon annealing, are stabilized by the interaction with the reduced silica sites, as indicated from CO temperature programmed desorption (TPD) titration measurements. Acetylene conversion to ethylene and benzene has been studied as a probe reaction, revealing the modification of selectivity and reactivity enhancement in addition to improved thermal stability on substrates rich in reduced-silica sites. These observations suggest that these unique sites play an important role in anchoring thermodynamically metastable conformations of supported Au-Pd bimetallic catalysts and dictate their high-temperature activity. PMID:23659535

Gross, Elad; Sorek, Elishama; Murugadoss, Arumugam; Asscher, Micha

2013-05-21

296

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.

297

Galileo photometry of asteroid 243 Ida  

USGS Publications Warehouse

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

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

1996-01-01

298

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

PubMed

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, Ca(2+)-induced Ca(2+) 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 Ca(2+) transients was significantly increased in unloaded cardiomyocytes (UN 227.4+/-24.9 ms(2), n=42 vs. C 157.8+/-18.0 ms(2), n=40; P<0.05). UN did not alter the action potential morphology or whole-cell L-type Ca(2+) current compared with C, but caused a significantly higher Ca(2+) spark frequency (UN 3.718+/-0.85 events/100 mum/s, n=47 vs. C 0.908+/-0.186 events/100 microm/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+/-1.12x10(5), n=57 vs. C 20.60+/- 3.174x10(5), 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. PMID:20430793

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

2010-09-01

299

uvby photometry of 2 Am and 2 mCP stars (Adelman+, 2003)  

NASA Astrophysics Data System (ADS)

Differential Stroemgren uvby observations from the Four College Automated Photoelectric Telescope (FCAPT) are presented for the metallic-lined stars 60 Tau and HR 1528 and the magnetic Chemically Peculiar stars HR 8216 and HR 8770. The first star, which is a {delta} Scuti variable, was found not to change its mean magnitudes. HR 1528 is best described as constant. A decade of photometry of HR 8216 shows that its b and y values have changed by -0.016 and -0.010mag, respectively, over this time and now can be considered a photometric variable. For HR 8770 a period of 5.3923 days is derived with the photometric variability being generally in phase. The light curves also suggest possible surface abundance inhomogeneities. (5 data files).

Adelman, S. J.

2003-01-01

300

Minor planets and related objects. IX - Photometry and polarimetry of /1685/ Toro.  

NASA Technical Reports Server (NTRS)

UBV photometry, lightcurves, a polarization-phase relation, and rotational polarization curves of Toro were obtained, June-August 1972. The average colors are B-V = 0.87 and U-B = 0.47 mag, showing some reddening with phase. The geometric albedo of Toro in the B filter is 0.14 which corresponds to an effective mean radius of 2.2 km plus or minus 0.4 (p.e.). The rotational polarization curves indicate that the lightcurves are mostly due to shape, but some albedo variation over the surface is detected as well. The shape is elongated, and probably irregular, with a cross-sectional area ratio of about 3.2, the maximum effective radius is 2.8 km and the minimum, 1.6 km.

Dunlap, J. L.; Gehrels, T.; Howes, M. L.

1973-01-01

301

STAR FORMATION IN THE OUTER DISKS OF SPIRAL GALAXIES: ULTRAVIOLET AND H{alpha} PHOTOMETRY  

SciTech Connect

We present an analysis of ultradeep UV and H{alpha} imaging of five nearby spiral galaxies to study the recent star formation in the outer disk. Using azimuthally averaged ellipse photometry as well as aperture photometry of individual young stellar complexes, we measure how star formation rates (SFRs) and UV and H{alpha} colors vary with radius. We detect azimuthally averaged UV flux to {approx}1.2-1.4 R{sub 25} in most galaxies; at the edge of the detected UV disk, the surface brightnesses are 28-29 mag arcsec{sup -2}, corresponding to SFR surface densities of {approx}3 Multiplication-Sign 10{sup -4} M{sub Sun} yr{sup -1} kpc{sup -2}. Additionally, we detect between 120 and 410 young stellar complexes per galaxy, with a significant number of detections out to {approx}1.5 R{sub 25}. We measure radial FUV-NUV profiles, and find that the dispersion in the UV colors of individual young stellar complexes increases with radius. We investigate how radial variations in the frequency of star formation episodes can create color gradients and increasing dispersion in the UV colors of star-forming regions, like those observed in our study. Specifically, we use recently published, high spatial and temporal resolution measurements of {Sigma}{sub SFR} throughout the disk of M33 to estimate the frequency of star formation episodes throughout the disk of a typical spiral galaxy. We use stellar synthesis models of these star formation histories (SFHs) to measure the variations in UV colors and find that we can replicate large dispersions in UV colors based on episodic SFHs.

Barnes, Kate L.; Van Zee, Liese [Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States); Skillman, Evan D., E-mail: barneskl@astro.indiana.edu, E-mail: vanzee@astro.indiana.edu, E-mail: skillman@astro.umn.edu [Department of Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

2011-12-20

302

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

303

Analysis Of The Morphology Of Comets Using Photometry: C/2009P1 Garrad And P1/Halley  

NASA Astrophysics Data System (ADS)

The surface brightness distribution of comet C/2009 P1 Garrad was studied to identify structure and fragmentation within the nucleus of the comet. Surface brightness mapping was done by performing pixel by pixel photometry on images taken of the comet taken in July 2011 using the PARI 0.35-m prime focus telescope. Comet Garrad's surface brightness maps are compared to those of 1P/Halley (1986) obtained from digitized images from Dyer Observatory photographic plates. That ollection of plates are now located in the PARI Astronomical Photographic Data Archive. Through the technique of pixel by pixel photometry and surface brightness mapping, comet nuclei may be studied more fully than by pure imaging, and some of the difficult to image structure of comet nuclei may be revealed. Results will presented that show that the nucleus of C/2009/P1 Garrad is a single elongated object. However, it has the indications of possible future fragmentation as seen in the brightness maps of the comet.

Mehnert, Herbert; Cline, J.; Castelaz, M.

2012-01-01

304

Spectroscopy and photometry of binary stars in old open clusters  

NASA Astrophysics Data System (ADS)

We have performed a spectroscopic and photometric study of six contact binary stars in four old open clusters, M67, Praesepe, NGC 6791 and NGC 752, in order to evaluate their suitability for measuring the distance to their respective clusters. The technique being tested uses the cosine Fourier coefficients of the light curves of the binary stars, and the mass ratios obtained spectroscopically, to provide distances to the binaries. The contact binary TX Cnc was used to obtain the distance to Praesepe, which we find to be (V-MV) o = 6.30 ± 0.08, which is in good agreement with the values of V-MV = 6.20 6.35 found in color-magnitude diagram (CMD) studies. We obtained a distance modulus of (V-MV) o = 12.71 ± 0.44 for V7 in NGC 6791, the oldest cluster in our survey. This agrees within ˜1? the values of 13.3 ? ( V-MV) ? 13.42 obtained by isochrone fitting of the cluster CMD. Our spectroscopic study of QX And in NGC 752 provided a distance modulus of V-MV = 8.30 ± 0.07 for this cluster. This compares to a value of V-MV = 7.9 ± 0.1 obtained by Milone et al. (1995) using the same star, but is in good agreement with V-MV = 8.25 ± 0.10 obtained by Daniel et al. (1994) from the CMD. The distances to the clusters as determined from the contact binaries using our procedure do not seem to give systematically smaller or larger distances as compared to CMD fitting. However, we have measured the distances to only three clusters, and only one object per cluster, and so establishing any systematic differences may require a larger survey. For the four clusters in this work, our new distance moduli and those of CMD fitting are in good agreement in all cases. We conclude that contact binaries could very well provide good distance indicators to their parent clusters. Surveys such as the Canada-France-Hawaii Legacy Survey will discover many contact binaries for which full least-squares orbital solutions will not be possible due to the large volume of data. The technique developed here should provide good preliminary orbital parameters for such binary star systems. The cosine Fourier coefficients of the light curve of EV Cnc in M67 lie off the grid of values for contact binaries, which leads us to speculate that this star may be an Algol system, rather than a contact binary. EV Cnc also exhibits the O'Connell effect, which in this case may be caused by a hot spot created on the surface of the primary by the impact of a gas stream. Consistent with this idea is the fact that EV Cnc's velocity curve exhibits blue-shifted velocities near the secondary eclipse, which may be due to a gas stream which transfers mass from the secondary to the primary in a semi-detached system. As a result, EV Cnc in M67 was found to be unsuitable for distance determinations. Our photometry of the contact binary AH Cnc in M67 indicates a possible new feature in its light curve. After secondary minimum, this star exhibits a 0.1 magnitude increase in brightness over a short time scale. Such a phenomenon has not previously been reported in any of the W UMa stars.

Blake, Ronald Melvin

305

Extinctions and Distances of Dark Clouds from Ugrijhk Photometry of Red Clump Giants: the North America and Pelican Nebulae Complex  

NASA Astrophysics Data System (ADS)

A possibility of applying 2MASS J, H, Ks, IPHAS r, i and MegaCam u, g photometry of red giants for determining distances to dark clouds is investigated. Red clump giants with a small admixture of G5--K1 and M2--M3 stars of the giant branch can be isolated and used in determining distances to separate clouds or spiral arms. Interstellar extinctions of background red giants can be also used for mapping dust surface density in the cloud.

Straižys, V.; Laugalys, V.

306

Photometry and spectroscopy in the open cluster Alpha Persei, 2  

NASA Technical Reports Server (NTRS)

Results from a combination of new spectroscopic and photometric observations in the lower main-sequence and pre-main sequence of the open cluster alpha Persei are presented. New echelle spectroscopy has provided radial and rotational velocity information for thirteen candidate members, three of which are nonmembers based on radial velocity, absence of a Li 6707A feature, and absence of H-alpha emission. A set of revised rotational velocity estimates for several slowly rotating candidates identified earlier is given, yielding rotational velocities as low as 7 km/s for two apparent cluster members. VRI photometry for several pre-main sequence members is given; the new (V,V-I(sub K)) photometry yields a more clearly defined pre-main sequence. A list of approximately 43 new faint candidate members based on the (V,V-I(sub K)) CCD photometry is presented in an effort to identify additional cluster members at very low masses. Low-dispersion spectra obtained for several of these candidates provide in some cases supporting evidence for cluster membership. The single brown dwarf candidate in this cluster is for the first time placed in a color-magnitude diagram with other cluster members, providing a better means for establishing its true status. Stars from among the list of new photometric candidates may provide the means for establishing a sequence of cluster members down to very faint magnitudes (V approximately 21) and consequently very low masses. New coordinate determinations for previous candidate members and finding charts for the new photometric candidates are provided in appendices.

Prosser, Charles F.

1993-01-01

307

Multicolor Photometry of the Merging Galaxy Cluster A2319: Dynamics and Star Formation Properties  

NASA Astrophysics Data System (ADS)

Asymmetric X-ray emission and a powerful cluster-scale radio halo indicate that A2319 is a merging cluster of galaxies. This paper presents our multicolor photometry for A2319 with 15 optical intermediate filters in the Beijing-Arizona-Taiwan-Connecticut (BATC) system. There are 142 galaxies with known spectroscopic redshifts within the viewing field of 58' × 58' centered on this rich cluster, including 128 member galaxies (called sample I). A large velocity dispersion in the rest frame, 1622^{+91}_{-70} km s-1, suggests merger dynamics in A2319. The contour map of projected density and localized velocity structure confirm the so-called A2319B substructure, at ~10' northwest to the main concentration A2319A. The spectral energy distributions (SEDs) of more than 30,000 sources are obtained in our BATC photometry down to V ~ 20 mag. A u-band (~3551 Å) image with better seeing and spatial resolution, obtained with the Bok 2.3 m telescope at Kitt Peak, is taken to make star-galaxy separation and distinguish the overlapping contamination in the BATC aperture photometry. With color-color diagrams and photometric redshift technique, 233 galaxies brighter than h BATC = 19.0 are newly selected as member candidates after an exclusion of false candidates with contaminated BATC SEDs by eyeball-checking the u-band Bok image. The early-type galaxies are found to follow a tight color-magnitude correlation. Based on sample I and the enlarged sample of member galaxies (called sample II), subcluster A2319B is confirmed. The star formation properties of cluster galaxies are derived with the evolutionary synthesis model, PEGASE, assuming a Salpeter initial mass function and an exponentially decreasing star formation rate (SFR). A strong environmental effect on star formation histories is found in the manner that galaxies in the sparse regions have various star formation histories, while galaxies in the dense regions are found to have shorter SFR time scales, older stellar ages, and higher interstellar medium metallicities. For the merging cluster A2319, local surface density is a better environmental indicator rather than the cluster-centric distance. Compared with the well-relaxed cluster A2589, a higher fraction of star-forming galaxies is found in A2319, indicating that the galaxy-scale turbulence stimulated by the subcluster merger might have played a role in triggering the star formation activity.

Yan, Peng-Fei; Yuan, Qi-Rong; Zhang, Li; Zhou, Xu

2014-05-01

308

UBV photometry of 56 Ari: 1990-1994  

NASA Astrophysics Data System (ADS)

We report on five seasons of UBV photometry of 56 Ari obtained with the 0.4-m telescope of the Braeside Observatory starting in the fall of 1990. These observations were part of the data used by Adelman et al. (2001) to find the very slow decrease in the main period of this magnetic CP star and the secondary period of approximately 5 years. Comparison of the light curves obtained in different seasons even with the same telescope tend to show slight discrepancies.

Fried, R. E.; Adelman, S. J.

2003-01-01

309

Io hot spots - Infrared photometry of satellite occultations  

NASA Technical Reports Server (NTRS)

Io's active hot spots, which are presently mapped on the basis of IR photometry of this moon's occultation by other Gallilean satellites, are obtained with greatest spatial resolution near the sub-earth point. A model is developed for the occultation lightcurves, and its fitting to the data defines the apparent path of the occulting satellite relative to Io; the mean error in apparent relative position of occulting satellites is of the order of 178 km. A heretofore unknown, 20-km diameter hot spot is noted on Io's leading hemisphere.

Goguen, J. D.; Matson, D. L.; Sinton, W. M.; Howell, R. R.; Dyck, H. M.

1988-01-01

310

Spitzer\\/IRAC Photometry of the Eta Chameleontis Association  

Microsoft Academic Search

We present IRAC 3.6, 4.5, 5.8 and 8 micron photometry for the 17 A, K and M\\u000atype members of the Eta Chameleontis association. These data show infrared\\u000aexcesses toward six of the 15 K and M stars, indicating the presence of\\u000acircumstellar disks around 40% of the stars with masses of 0.1-1 solar mass.\\u000aThe two A-stars show no

S. T. Megeath; L. Hartmann; K. L. Luhman; G. G. Fazio

2005-01-01

311

uvby photometry in McCormick proper motion fields  

NASA Technical Reports Server (NTRS)

The Danish 50 cm telescope at the European Southern Observatory was used to obtain high-precision uvby photometry for 50 F2 to G2 stars, with V values in the 9.4-12.3 mag range, which were selected in the southern galactic polar regions of the McCormick proper motion fields and measured on six different nights. The brighter stars are found to systematically exhibit smaller m(1) indices, of about 0.02 mag, upon comparison with the earlier data of Blaauw et al (1976). Single measurements are given for 98 stars in eight McCormick fields at intermediate southern galactic latitudes.

Degewij, J.

1982-01-01

312

UBVRI photometry of the FK5 Extension Catalogue Stars  

NASA Astrophysics Data System (ADS)

UBVRI photometry in the Kron-Cousins system for 272 stars of the Extension Catalogue of the Fifth Fundamental Star Catalogue (FK5 stars) in the declination zone +7 deg to -90 deg is presented. Tables 1-2 are also 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 Based on observations made at the European Southern Observatory, La Silla, Chile.

Carrasco, G.; Ledoux, C.; Loyola, P.

1997-12-01

313

Long-term photometry of Variables III (Manfroid+, 1995)  

NASA Astrophysics Data System (ADS)

This is the third catalogue of photometric data in the Stroemgren system obtained during the period October 1990-January 1992 in the framework of the Long-Term Photometry of Variables (LTPV) program at the European Southern Observatory. All data have been obtained with the Danish 50-cm telescope. The mean values of the r.m.s. deviations of the differential measurements of comparison stars are around (from Table 4 of paper) ------------------------------ y b-y m1 c1 ------------------------------ 0.005 0.002 0.004 0.006 ------------------------------ (2 data files).

Manfroid, J.; Sterken, C.; Cunow, B.; de Groot, M.; Jorissen, A.; Kneer, R.; Krenzin, R.; Kruijswijk, M.; Naumann, M.; Niehues, M.; Schoeneich, W.; Sevenster, M.; Vos, N.; Vogt, N.

1995-11-01

314

Multicolour time series photometry of three periodic ultracool dwarfs  

NASA Astrophysics Data System (ADS)

Photometry in I, or contemporaneously in I and R, of the known variable ultracool dwarfs Kelu-1 and 2MASS J11553952-3727350 is presented. The nature of the variability of Kelu-1 appears to evolve on time-scales of a day or less. Both the period and amplitude of the variability of 2MASS J11553952-3727350 have changed substantially since publication of earlier observations of the object. DENIS 1454-6604 is a new variable ultracool dwarf, with persistent and prominent brightness modulations at a period of 2.6 h.

Koen, Chris

2013-02-01

315

Limits to CCD ensemble photometry precision, and prospects for asteroseismology  

NASA Astrophysics Data System (ADS)

Results are reported of CCD-ensemble time-resolved photometry with the KPNO 2.1-m telescope yielding precision of 400 micromag per minute of integration. Detailed stellar-evolution modeling and eigenfrequency-analysis results are given for the stars of the old open cluster M67. Using observed amplitudes of solar p-mode oscillations, and published scaling laws with spectral type, direct detection of solar-analog oscillations on 13th-magnitude M67 stars is possible with a several-night 4-m network campaign. Asteroseismology on a substantial ensemble of cluster stars promises to allow fundamental tests of stellar structure and evolution theory.

Gilliland, Ronald L.; Brown, Timothy M.

1992-07-01

316

Vilnius Photometry in two Nebulae (Straizys et al., 1993)  

NASA Astrophysics Data System (ADS)

The results of photoelectric photometry of 564 stars in the Vilnius seven-color system in three areas near the North America and Pelican nebulae are given. Photometric spectral types, absolute magnitudes, colour excesses, interstellar extinctions and distances of the stars are determined. We find that the dark cloud separating both nebulae is at 580pc distance. A number of stars immersed into the dark cloud have been found. It seems that the dark cloud extends to south down to 40deg declination. The area southwest of ? Cyg in the declination zones 42 and 43deg is comparatively transparent at least up to 1kpc. (6 data files).

Straizys, V.; Kazlauskas, A.; Cernis, K.; Vansevicius, V.

1994-11-01

317

Photometric redshifts determinations for galaxies by means of multicolor photometry  

NASA Astrophysics Data System (ADS)

Multicolor photometry is increasingly used for galaxies redshifts estimations. Using optical and NIR photometrical data and HST/WFPC2 morphological data we analyze the environments of radio galaxies 3C 184 (z = 0.996, 35 galaxies in a 6.2 arcmin2 field) and 3C 210 (z = 1.169, 57 galaxies in a 6.2 arcmin2 field). Color - color diagrams, red sequence technique and template fitting technique are used in order to determine the photometric redshifts of galaxies and to analyze the clustering of galaxies and ERGs (extremely red galaxies) in the environment of these two radio galaxies at z ~ 1.

Popescu, Nedelia A.

2007-03-01

318

ZJ VISTA photometry in NGC253 stellar halo (Greggio+, 2014)  

NASA Astrophysics Data System (ADS)

This catalogue lists position, magnitude and photometric error of stellar sources identified on the VISTA Z and J images of the NGC 253 spiral galaxy. The data were analyzed with the VISTA data flow system at the Cambridge University Astronomy Survey Unit, and photometry carried out with the imcore package, which provides a morphological classification for each detection. The catalogue presented here is referred to as Catalogue B in the paper, and includes sources classified as stellar or likely stellar in both filter (Type=1), plus sources classified as stellar on the J and extended on the Z tile (Type=4). The last column of the catalogue reports this classification. (1 data file).

Greggio, L.; Rejkuba, M.; Gonzales, O. A.; Arnaboldi, M.; Iodice, E.; Irwin, M.; Neeser, M. J.; Emerson, J.

2014-02-01

319

Hardness Ratio Estimation in Low Counting X-Ray Photometry  

NASA Astrophysics Data System (ADS)

Hardness ratios are commonly used in X-ray photometry to roughly indicate spectral properties. They are usually defined as the ratio of counts in two different wave bands. This definition, however, is problematic when the counts are very limited. Here we instead define the hardness ratio using the ?-parameter of Poisson processes and develop an estimation method via Bayesian statistics. Our Monte Carlo simulations show the validity of our method. Based on this new definition we can estimate the hydrogen column density for the photoelectric absorption of X-ray spectra in the case of low counting statistics.

Jin, Y. K.; Zhang, S. N.; Wu, J. F.

2006-12-01

320

IRAC Photometry of 400-800K Brown Dwarfs  

NASA Astrophysics Data System (ADS)

Spitzer data, including warm-IRAC [3.6] and [4.5] photometry, is critical for understanding the cold population of brown dwarfs now being found, objects which have more in common with planets than stars. As effective temperature drops from 800K to 400K, the fraction of flux emitted beyond 3um increases rapidly, from about 40% to >75%. This rapid increase makes a color like H-[4.5] a very sensitive temperature indicator, and it can be combined with a gravity- and metallicity-sensitive color like H-K to constrain all three of these fundamental properties, which in turn gives us mass and age for these, generally isolated, slowly cooling objects. Our goal is to accurately characterise the temperature/ gravity/ metallicity distribution of the coolest brown dwarfs being found in the UKIRT Infrared Deep Sky Survey, which is only possible if Spitzer photometry is available to complement our near- infrared data. At the same time we will define color trends which will allow better exploitation of the WISE mission by the community. We expect to find and spectroscopically confirm several new 400 - 800K brown dwarfs during Cycle 7, and possibly even cooler nearby objects (based on our recent discovery of a 400K object at a distance of only 3pc). Extrapolating from our current sample, we expect to trigger around eleven low-impact ToO observations during Cycle 7, totalling 9.9 hours of AORs.

Leggett, Sandy; Warren, Steve; Lucas, Phil; Burningham, Ben; Pinfield, David; Marley, Mark; Saumon, Didier

2010-06-01

321

PHOTOMETRY OF VARIABLE STARS FROM DOME A, ANTARCTICA  

SciTech Connect

Dome A on the Antarctic plateau is likely one of the best observing sites on Earth thanks to the excellent atmospheric conditions present at the site during the long polar winter night. We present high-cadence time-series aperture photometry of 10,000 stars with i < 14.5 mag located in a 23 deg{sup 2} region centered on the south celestial pole. The photometry was obtained with one of the CSTAR telescopes during 128 days of the 2008 Antarctic winter. We used this photometric data set to derive site statistics for Dome A and to search for variable stars. Thanks to the nearly uninterrupted synoptic coverage, we found six times as many variables as previous surveys with similar magnitude limits. We detected 157 variable stars, of which 55% were unclassified, 27% were likely binaries, and 17% were likely pulsating stars. The latter category includes {delta} Scuti, {gamma} Doradus, and RR Lyrae variables. One variable may be a transiting exoplanet.

Wang Lingzhi [Department of Astronomy, Beijing Normal University, Beijing 100875 (China); Macri, Lucas M.; Krisciunas, Kevin; Wang Lifan [Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Ashley, Michael C. B.; Lawrence, Jon S.; Luong-Van, Daniel; Storey, John W. V. [School of Physics, University of New South Wales, NSW 2052 (Australia); Cui Xiangqun; Gong Xuefei; Yuan Xiangyan [Nanjing Institute of Astronomical Optics and Technology, Nanjing 210042 (China); Feng Longlong; Yang Ji; Zhu Zhenxi [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Liu Qiang; Zhou Xu [National Astronomical Observatory of China, Chinese Academy of Sciences, Beijing 100012 (China); Pennypacker, Carl R. [Center for Astrophysics, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Shang Zhaohui [Department of Physics, Tianjin Normal University, Tianjin 300074 (China); Yang Huigen [Polar Research Institute of China, Pudong, Shanghai 200136 (China); York, Donald G. [Department of Astronomy and Astrophysics and Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)

2011-11-15

322

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

NASA Astrophysics Data System (ADS)

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. These clusters are in fact located in the third Galactic quadrant. We aim to obtain the basic parameters of these objects, which in some cases are still disputed in the literature. In the case of VdB-Hagen 4 we provide the first estimate of its fundamental parameters, while for Haffner 8 we present the first CCD photometry. The analysis is based on the comparison between field star decontaminated color-magnitude diagrams and stellar models. Particular care is devoted to the the assessment of the data quality and the statistical field star decontamination. The Padova library of stellar isochrones is adopted in this study. The analysis we carried out allowed us to solve a few inconsistencies in the literature regarding Haffner 8 and NGC 2509. Collinder 74 is found to be significantly older than reported before. VdB-Hagen 4 is a young open cluster located more than 20kpc from the Galactic center. Such an extreme distance is compatible with the cluster belonging to the Norma-Cygnus arm. (5 data files).

Carraro, G.; Costa, E.

2007-01-01

323

The MOST Asteroseismology Mission: Ultraprecise Photometry from Space  

NASA Astrophysics Data System (ADS)

The Microvariablity and Oscillations of Stars (MOST) mission is a low-cost microsatellite designed to detect low-degree acoustic oscillations (periods of minutes) with micromagnitude precision in solar-type stars and metal-poor subdwarfs. There are also plans to detect light reflected from giant, short-period, extrasolar planets and the oscillations of roAp stars and the turbulent variability in the dense winds of Wolf-Rayet stars. This paper describes the experiment and how we met the challenge of ultraprecise photometry despite severe constraints on the mass, volume, and power available for the instrument. A side-viewing, 150 mm aperture Rumak-Maksutov telescope feeds two frame-transfer CCDs, one for tracking and the other for science. There is a single 300 nm wide filter centered at 525 nm. Microlenses project Fabry images of the brighter (V<=10) target stars onto the science CCD. Fainter target stars will be focused directly elsewhere on the CCD. MOST was launched on 2003 June 30 into a low-Earth, Sun-synchronous, polar orbit allowing stars between -19° and +36° declination to be viewed continuously for up to 60 days. Attitude is controlled by reaction wheels and magnetotorquers. A solar safety shutter over the telescope diagonal is the only other moving part. Accumulated photometry will be used to calibrate response across the target field stop, and data will be compressed and downloaded to three dedicated ground stations.

Walker, Gordon; Matthews, Jaymie; Kuschnig, Rainer; Johnson, Ron; Rucinski, Slavek; Pazder, John; Burley, Gregory; Walker, Andrew; Skaret, Kristina; Zee, Robert; Grocott, Simon; Carroll, Kieran; Sinclair, Peter; Sturgeon, Don; Harron, John

2003-09-01

324

Stromvil CCD Photometry in Globular Cluster M 3  

NASA Astrophysics Data System (ADS)

We observed the globular cluster M 3 in the 7-band Stromvil system plus Vilnius X-band at the 1.8-m Vatican Advanced Technology Telescope with a 2K CCD giving a 6-arcmin field. We observed the open cluster M 67 in the same run. Here from the residuals of many stars fit to quality CCD Vilnius photometry (Laugalys et al., 2004, Baltic Astronomy, 13, 1) we reshape and thus correct the initial flatfields. M 67 with a wide color base gives the color transformations of the run by calibrating from about 12 photoelectric standards in the Stromvil and similar Vilnius systems. In M 3 six photoelectric standards of moderate quality, all red stars of 13th magnitude in the Vilnius system calibrate the zero-point magnitude scale. Point-spread-function fitting to the stars in the crowded M 3 field resolves blends. With relatively short exposures of minutes a limiting magnitude V=15 is obtained with a signal/noise ratio about 100. So from this new photometry we subsequently can classify all types of stars and treat questions of reddening, distances, membership and metallicity at least at the horizontal branch of the cluster.

Boyle, Richard P.; Janusz, R.; Philip, A. G. D.; Straizys, V.; Vrba, F.

2007-12-01

325

UBV(RI) photometry of cool stars (Cutispoto+, 1996)  

NASA Astrophysics Data System (ADS)

We present high-precision UBV(RI)c photometry for a sample of stars detected serendipitously by the EXOSAT satellite. Fourteen objects, out of 47 likely optical counterparts, turned out to be clearly variable, with periods in the range 1-8 days, including a newly discovered eclipsing binary. For most of them the optical variability is consistent with the presence of photospheric cool spots. We have used our multicolour photometry to estimate spectral classifications and distances. The derived distances indicate that some of the observed stars are previously unidentified nearby (d<=25pc) M dwarfs. When combined with the results of high resolution spectroscopy, our photometric observations allow us to investigate the stellar content of the selected X-ray sample. Young stars and RS CVn-type binaries appear to constitute a large fraction of the selected sample. For a description of the UBV and (RI)c photometric systems, see e.g. http://obswww.unige.ch/gcpd/ph01.html and http://obswww.unige.ch/gcpd/ph54.html. (2 data files).

Cutispoto, G.; Tagliaferri, G.; Pallavicini, R.; Pasquini, L.; Rodono, M.

1995-09-01

326

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

327

Photometry and Spectroscopy of GRB 030329 and Its Associated Supernova 2003dh: The First Two Months  

Microsoft Academic Search

We present extensive optical and infrared photometry of the afterglow of gamma-ray burst (GRB) 030329 and its associated supernova (SN) 2003dh over the first two months after detection (2003 March 30-May 29 UT). Optical spectroscopy from a variety of telescopes is shown and, when combined with the photometry, allows an unambiguous separation between the afterglow and SN contributions. The optical

T. Matheson; P. M. Garnavich; K. Z. Stanek; D. Bersier; S. T. Holland; K. Krisciunas; N. Caldwell; P. Berlind; J. S. Bloom; M. Bolte; A. Z. Bonanos; M. J. I. Brown; W. R. Brown; M. L. Calkins; P. Challis; R. Chornock; L. Echevarria; D. J. Eisenstein; M. E. Everett; A. V. Filippenko; K. Flint; R. J. Foley; D. L. Freedman; Mario Hamuy; P. Harding; N. P. Hathi; M. Hicken; C. Hoopes; C. Impey; B. T. Jannuzi; R. A. Jansen; S. Jha; J. Kaluzny; S. Kannappan; R. P. Kirshner; D. W. Latham; J. C. Lee; D. C. Leonard; W. Li; K. L. Luhman; P. Martini; H. Mathis; J. Maza; S. T. Megeath; L. R. Miller; D. Minniti; E. W. Olszewski; M. Papenkova; M. M. Phillips; B. Pindor; D. D. Sasselov; R. Schild; H. Schweiker; T. Spahr; J. Thomas-Osip; I. Thompson; D. Weisz; R. Windhorst; D. Zaritsky

2003-01-01

328

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

PubMed Central

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.

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

2013-01-01

329

Affective Domain  

NSDL National Science Digital Library

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

330

Feasibility of spectro-photometry in X-rays (SPHINX) from the moon  

NASA Astrophysics Data System (ADS)

Doing space Astronomy on lunar surface has several advantages. We present here feasibility of an All Sky Monitoring Payload for Spectro-photometry in X-rays (SPHINX) which can be placed on a lander on the moon or in a space craft orbiting around the moon. The Si-PIN photo-diodes and CdTe crystals are used to detect solar flares, bright gamma bursts, soft gamma-ray repeaters from space and also X-ray fluorescence (XRF) from lunar surface. We present the complete Geant4 simulation to study the feasibility of such an instrument in presence of Cosmic Diffused X-Ray Background (CDXRB). We find that the signal to noise ratio is sufficient for moderate to bright GRBs (above 5 keV), for the quiet sun (up to 100 keV), solar flares, soft gamma-ray repeaters, X-ray Fluorescence (XRF) of lunar surface etc. This is a low-cost system which is capable of performing multiple tasks while stationed at the natural satellite of our planet.

Sarkar, Ritabrata; Chakrabarti, Sandip Kumar

2010-08-01

331

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.

2013-12-01

332

FSL Constructs: A Simple Method for Modifying Cell/Virion Surfaces with a Range of Biological Markers Without Affecting their Viability  

PubMed Central

The ability to modify/visualize biological surfaces, and then study the modified cell/virion in a range of in vitro and in vivo environments is essential to gaining further insight into the function of specific molecules or the entire entity. Studies of biological surface modification are generally limited to genetic engineering of the organism or the covalent attachment of chemical moieties to the cell surface1,2. However these traditional techniques expose the cell to chemical reactants, or they require significant manipulation to achieve the desired outcome, making them cumbersome, and they may also inadvertently affect the viability/functionality of the modified cell. A simple method to harmlessly modify the surface of cells is required. Recently a new technology, KODE Technology has introduced a range of novel constructs consisting of three components: a functional head group (F), a spacer (S) and a lipid tail (L) and are known as Function-Spacer-Lipid or FSL constructs3. The spacer (S) is selected to provide a construct that is dispersible in water, yet will spontaneously and stably incorporate into a membrane. FSL construct functional moieties (F) so far include a range of saccharides including blood group-related determinants, sialic acids, hyaluronan polysaccharides, fluorophores, biotin, radiolabels, and a range of peptides3-12. FSL constructs have been used in modifying embryos, spermatozoa, zebrafish, epithelial/endometrial cells, red blood cells, and virions to create quality controls systems and diagnostic panels, to modify cell adhesion/ interaction/ separation/ immobilization, and for in vitro and in vivo imaging of cells/virions3-12. The process of modifying cells/virions is generic and extremely simple. The most common procedure is incubation of cells (in lipid free media) with a solution for FSL constructs for 1-2 hours at 37°C4-10. During the incubation the FSL constructs spontaneously incorporate into the membrane, and the process is complete. Washing is optional. Cells modified by FSL constructs are known as kodecytes6-9, while virions are kodevirions10. FSL constructs as direct infusions and kodecytes/kodevirions have been used in experimental animal models7,8,10. All kodecytes/kodevirions appear to retain their normal vitality and functionality while gaining the new function of the F moiety7,8,10,11. The combination of dispersibility in biocompatible media, spontaneous incorporation into cell membranes, and apparent low toxicity, makes FSL constructs valuable research tools for the study of cells and virions.

Blake, Deborah A.; Bovin, Nicolai V.; Bess, Dan; Henry, Stephen M.

2011-01-01

333

UBVI CCD Photometry of the Old Open Cluster NGC 1193  

NASA Astrophysics Data System (ADS)

We present UBVI photometry of the old open cluster NGC 1193. Color-magnitude diagrams (CMDs) of this cluster show a well defined main sequence and a sparse red giant branch. For the inner region of r<50 arcsec, three blue straggler candidates are newly found in addition to the objects Kaluzny (1988) already found. The color-color diagrams show that the reddening value toward NGC 1193 is E(B-V) =0.19 ± 0.04. From the ultraviolet excess measurement, we derived the metallicity to be [Fe/H]=-0.45 ± 0.12. A distance modulus of (m-M)_0 =13.3 ± 0.15 is obtained from zero age main sequence fitting with the empirically calibrated Hyades isochrone of Pinsonneault et al. (2004). CMD comparison with the Padova isochrones by Bertelli et al. (1994) gives an age of log t =9.7 ± 0.1.

Kyeong, Jaemann; Kim, Sang Chul; Hiriart, David; Sung, Eon-Chang

2008-12-01

334

Unveiling an exoplanetary Neptunian atmosphere through multiband transit photometry  

NASA Astrophysics Data System (ADS)

The ``effective'' radius of a planet is a function of wavelength due to scattering and/or absorption processes, and we can exploit simultaneous multiband transit photometry to probe the atmospheric scale height and composition. We present new photometric data of the recently discovered ``hot Uranus'' GJ3470b, gathered with the LBC camera at LBT. Light curves of unprecedented accuracy (0.0012 mag in U and 0.00028 mag in a narrow band centered at 972 nm) allowed us to measure an increasingly larger planetary radius at shorter wavelengths, which we interpret as a signature of Rayleigh scattering by a large scale height atmosphere. Further follow-up observations to confirm this result and probe the presence of specific atomic and molecular species is ongoing.

Nascimbeni, V.; Piotto, G.; Pagano, I.; Scandariato, G.

2014-01-01

335

XQED: The new Whole Earth Telescope photometry analysis package  

NASA Astrophysics Data System (ADS)

For many years, the Whole Earth Telescope (WET) has used the DOS based QED software package, created by R. E. Nather, to reduce the data gathered from the WET standard, PMT based photometers. Recently, many WET participants have migrated to CCD based photometers, and the old software is unable to reduce their data. To accomodate the transition, a new data reduction and analysis package has been created, XQED. XQED is an Xwindows based program, designed to allow observers to reduce light curves quickly and accurately after completing the CCD photometry extraction. It includes methods for sky subtraction, extinction and corrections for clouds or other transient phenomena among its many tools. It is meant to be as user friendly as possible and still flexible enough to allow the observer to do whatever is necessary to analyze their data. XQED is being designed for the community at large, so that others may take advantage of the methods used by the WET participants.

Riddle, R. L.

2003-12-01

336

uvby photometry of 4 CP stars (Adelman 1999)  

NASA Astrophysics Data System (ADS)

Differential Stroemgren uvby photometry obtained with the Four College Automated Photoelectric Telescope shows that the hot HgMn star 33 Gem is photometrically constant. The Si star HD 15980 is found to be a variable whose period is significantly greater than 2 years. The unusual magnetic chemically peculiar Co star HR 1094 is discovered to be a low amplitude photometric variable with the magnetic field period of Hill & Blake (1996MNRAS.278..183H), 2.9761 days. The ephemeris for the magnetic chemically peculiar star HD 115708 of Wade et al. (1996A&A...307..500W) is confirmed with the error in its period of 5.07622 days being greatly reduced. The u, v, b, and y light curves for both HR 1094 and HD 115708 exhibit differences which indicate complex elemental photospheric abundance distributions. (7 data files).

Adelman, S. J.

1998-07-01

337

ubvy Photometry of magnetic CP stars (Adelman+ 1994)  

NASA Astrophysics Data System (ADS)

Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope of four magnetic Chemically Peculiar stars are presented. We refined the period of 63 And to 4.1890 days. The period of the sharp-lined Si star HD 192913 is 16.840 days, a value close to, but slightly different from published values. HR 8240, a sharp-lined Si star, is found not to be a photometric variable. Comparison of four color photometry of 108 Aqr by Morrison and Wolff and from the Four College APT indicates that subtle changes in the shapes of the light curves, especially that for u, have occurred suggesting that this star may be precessing. (4 data files).

Adelman, S. J.; Knox, J. R., Jr.

1993-10-01

338

USING PHOTOMETRY TO PROBE THE CIRCUMSTELLAR ENVIRONMENT OF {delta} SCORPII  

SciTech Connect

We acquired Johnson BV photometry of the binary Be disk system {delta} Scorpii during its 2009, 2010, 2011, and 2012 observing seasons and used it to probe the innermost regions of the disk. We found that several disk building events have occurred during this time, resulting in an overall brightening in the V band and reddening of the system. In addition to these long-term trends, we found cyclical variability in each observing season on timescales between 60 and 100 days. We were able to reproduce the changes in the magnitude and color of {delta} Sco using our theoretical models and found that variable mass-loss rates in the range 2.5-7.0 Multiplication-Sign 10{sup -9} M{sub Sun} yr{sup -1} over {approx}35 days can reproduce the observed increase in brightness.

Jones, C. E.; Wiegert, P. A.; Cyr, R. P.; Halonen, R. J. [Department of Physics and Astronomy, Western University, London, ON N6A 3K7 (Canada); Tycner, C. [Department of Physics, Central Michigan University, Mt. Pleasant, MI 48859 (United States); Henry, G. W.; Muterspaugh, M. W. [Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Blvd., Box No 9501, Nashville, TN 37209 (United States)

2013-05-15

339

CCD-photometry of galactic globular clusters. III - NGC 6171  

NASA Astrophysics Data System (ADS)

This study presents B and V CCD photometry for 1565 stars in the low-concentration globular cluster NGC 6171 = M107. The morphology yielded by previous photometric studies is confirmed by the overall color-magnitude-diagram (CMD) properties. Metal abundance indicators derived from the CMD leading to Fe/H = - 0.89 +/-0.20, the study of the RGB intrinsic width, and the detection of the RGB bump are presented. A star count and a morphological analysis of the various branches are made, the primordial helium abundance is estimated, and the claimed lack of RGB stars and the peculiar radial distribution of RGB stars with respect to the HB ones are investigated. A description of the main sequence and an estimate of the relative age of the cluster within the scheme presented by Buonanno et al. (1989, 1990) are presented.

Ferraro, F. R.; Clementini, G.; Fusi Pecci, F.; Buonanno, R.

1991-10-01

340

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

341

An interactive modular design for computerized photometry in spectrochemical analysis  

NASA Technical Reports Server (NTRS)

A general functional description of totally automatic photometry of emission spectra is not available for an operating environment in which the sample compositions and analysis procedures are low-volume and non-routine. The advantages of using an interactive approach to computer control in such an operating environment are demonstrated. This approach includes modular subroutines selected at multiple-option, menu-style decision points. This style of programming is used to trace elemental determinations, including the automated reading of spectrographic plates produced by a 3.4 m Ebert mount spectrograph using a dc-arc in an argon atmosphere. The simplified control logic and modular subroutine approach facilitates innovative research and program development, yet is easily adapted to routine tasks. Operator confidence and control are increased by the built-in options including degree of automation, amount of intermediate data printed out, amount of user prompting, and multidirectional decision points.

Bair, V. L.

1980-01-01

342

Stromgren & Washington Photometry of dSph Systems  

NASA Astrophysics Data System (ADS)

Using the APO 3.5-m telescope, we have investigated the metallicity and age distributions of the dwarf spheroidal systems, Bootes I, CVn II, UMa II and Bootes II using a combination of Washington and Stromgren colors and indices. Our data shows that Bootes I and UMa II have a spread in [Fe/H] > 1 dex, using the red giant branch and the main sequence turn-off. Previous photometry and spectroscopy of the RGB stars in Bootes I have shown a spread in [Fe/H], but the use of the m1-index allows us to break the age-metallicity degeneracy and investigate the star formation history of these dark matter-dominated systems.

Hughes, Joanne D.

2009-05-01

343

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

344

Progress report on Washington Photometry of Several Galactic Globular Clusters.  

NASA Astrophysics Data System (ADS)

Washington photometry of M2, M72, M92 and NGC 4147 was carried out, at the JPL 0.6-m telescope at Table Mountain Facility, between June 1997 and December 1999. The long-term aim is to better estimate the ages of these objects and to better estimate the age of the Universe. The aim of the last two years has been to develop and refine techniques for taking exposures of up to 1 hour without the use of an auto-guider. This paper will discuss the advantages of long exposures over stacks of shorter ones, techniques for correcting telescope pointing for atmospheric refraction, the advantages of Washington System filters, and present some early results of the program. This work was carried out under a NASA Faculty Award for Research grant (P.I. Dr. William Taylor CSULA) and the NSF-funded JPL/CSULA Consortion for Undergraduate Research Experience.

Gillam, S.; Foster, J.; Atienza-Rosel, J.; Ates, A.; Gibson, H.; Rodriguez, M.; Bruton, C.; Osuji, B.; Bledsoe, E.

2000-05-01

345

Photometry and analysis of 27 asteroids (Lagerkvist+, 1995)  

NASA Astrophysics Data System (ADS)

In this paper photometry and analysis of 27 asteroids are presented. For the asteroids 21 Lutetia, 23 Thalia, 250 Bettina and 135 Hertha spin vector determinations were made. For asteroid 99 Dike we derived a rotation period of 10.35 hours and for 1280 Baillauda the period was found to be 12.6 hours. For 23 Thalia, 66 Maja and 250 Bettina the slope parameter was derived from the present data. The data are in a format "atlas 4" about which no explanation could be obtained from the authors. According to the authors, the data will be part of the Uppsala asteroid data base, described in the proceedings from the ACM 91 meeting in Belgirate edited by Milani et al (IAU symp. No 160), page 471; more details could be found at http://www.astro.uu.se/planet/ (1 data file).

Lagerkvist, C.-I.; Erikson, A.; Debehogne, H.; Festin, L.; Magnusson, P.; Mottola, S.; Oja, T.; de Angelis, G.; Belskaya, I. N.; Dahlgren, M.; Gonano-Beurer, M.; Lagerros, J.; Lumme, K.; Pohjolainen, S.

1995-05-01

346

Photometry and Spectroscopy with the SMARTS Consortium Telescopes  

NASA Astrophysics Data System (ADS)

We present recent results from the SMARTS Consortium Telescopes located at Cerro Tololo, designed to highlight the capabilities of the telescopes and instruments. We will report astrometry from the 0.9m+2KCCD obtained for the RECONS project (Dieterich et al. 2014 and Riedel et al. 2014), optical/IR photometry obtained with the 1.3m+ANDICAM for studies of X-ray binaries (e.g. MacDonald et al. 2014) and the SMARTS/Fermi blazar project (Bonning et al. 2012), and high-resolution spectroscopy obtained with the 1.5m+Chiron for exoplanet studies (Tokovinin et al. 2013). We note that time is available to new private partners on all these telescope/instrument combinations.

Bailyn, Charles D.; Buxton, Michelle; Misenti, Victoria; Fischer, Debra; Henry, Todd J.; Van Der Bliek, Nicole S.

2014-06-01

347

VI photometry of the galactic cluster Berkeley 66  

NASA Astrophysics Data System (ADS)

A colour magnitude diagram (CMD) extending to V ~= 19 mag is given for 444 stars in the region of the galactic cluster Berkeley 66. The V and I photometry of a nearby field is also reported. This object appears very faint, highly contaminated by foreground stars and very reddened. The apparent distance modulus (m-M) and the colour excess E_{V-I} are guessed to be 17.5 and 1.1, respectively, with an uncertainty of at least 30%. Adopting these values the comparison of the CMD with theoretical isochrones from the Padova group provides an age around 1.0 Gyr. Based on observations carried out at Pino Torinese Observatory, Torino, Italy. Table 2 is available only in electronic form at the CDS via anonymous ftp 130.79.128.5.

Guarnieri, M. D.; Carraro, G.

1997-03-01

348

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

349

HST photometry of M33 stellar clusters (Zloczewski+, 2009)  

NASA Astrophysics Data System (ADS)

We have used deep ACS/WFC images of M33 to check the nature of extended objects detected by the ground based survey of Zloczewski et al. (2008, Cat. J/AcA/58/23). A total of 24 candidates turned out to be genuine compact stellar clusters. In addition we detected 91 new clusters. Equatorial coordinates, integrated magnitudes and angular sizes are listed for all 115 objects. Forty-two clusters have sufficiently red colors to be candidates for old globulars. For four clusters we extracted resolved stellar photometry. Object 33-3-018 located in the outer disk of M33 turned out to be a young cluster with an age estimated at 200-350Myr. Cluster ZK-90 has an age of 3-5Gyr. The remaining two clusters have intermediate ages ranging from one to a few Gyr. (2 data files).

Zloczewski, K.; Kaluzny, J.

2010-07-01

350

The symbiosis of photometry and radial-velocity measurements  

NASA Technical Reports Server (NTRS)

The FRESIP mission is optimized to detect the inner planets of a planetary system. According to the current paradigm of planet formation, these planets will probably be small Earth-sized objects. Ground-based radial-velocity programs now have the sensitivity to detect Jovian-mass planets in orbit around bright solar-type stars. We expect the more massive planets to form in the outer regions of a proto-stellar nebula. These two types of measurements will very nicely complement each other, as they have highest detection probability for very different types of planets. The combination of FRESIP photometry and ground-based spectra will provide independent confirmation of the existence of planetary systems in orbit around other stars. Such detection of both terrestrial and Jovian planets in orbit around the same star is essential to test our understanding of planet formation.

Cochran, William D.

1994-01-01

351

Evaluation of urine culture screening by light-scatter photometry  

SciTech Connect

Urine screening for bacteriuria by light-scatter photometry (Autobac) was evaluated for accuracy and compared with a colony count by the calibrated loop method. Incubation time, inoculum size, precision, and interference of particulate matter were evaluated in an effort to standardize the screening procedure. Results showed that urines could be accurately screened for Enterobacteriaceae by inoculating a single Autobac cuvette chamber with 0.1 or 0.2 ml of urine and determining the voltage change after four hours. A change of greater than or equal to 0.2 units indicates significant bacteriuria. Decreased accuracy was noted for urines having greater than 10(5) cfu/ml of Pseudomonas species or gram-positive cocci, possibly because these organisms grow more slowly.

Hale, D.C.; Thrupp, L.D.; Matsen, J.M.

1981-08-01

352

Astrometry and Photometry of Binary Exoplanet Host Stars  

NASA Astrophysics Data System (ADS)

Using the adaptive optics system on the AEOS 3.6m telescope, we conducted an astrometry survey of stars hosting exo-planets discovered by radial velocity studies. The data were collected in I-band and multiple frames were collected and co-added to produce images capable of revealing faint stellar companions. The survey was intended to detect both optical and physical companions. Duplicity among exoplanet host stars can influence the planetary orbits. A census of faint background stars is important for coronagraphic imaging surveys, as it eliminates the possibility of mistagging a background star as a possible planetary companion. We present astrometry and photometry on 7 previously known binaries and for 8 newly detected companions. An additional 46 stars were observed with no signs of companions, We also present orbits for two of the previously known binaries: HIP 14954 (HD 19994 = HJ 663) and HIP 67275 (HD 120136 = STT 270).

ten Brummelaar, Theo; Turner, N. H.; Roberts, L. C., Jr.; Hartkopf, W. I.; Mason, B. D.

2009-12-01

353

Millisecond optical photometry of the DQ Herculis objects  

NASA Technical Reports Server (NTRS)

The results of millisecond optical photometry of the DQ Herculis stars EX Hya, H2252-035, V1223 Sgr, and AE Aqr obtained at the Las Campanas Observatory and Cerro Tololo Inter-American Observatory during the years 1985, 1986, and 1987 are reported. The data for coherent and incoherent features are searched for. Coherent features (other than those previously known) were not detected for frequencies between 0.1 and 250 Hz at 4-sigma upper limits of 0.05-0.4 percent. Evidence is not found for 1-3 s, quasi-coherent features. Such features have been detected in the optical emission of the AM Her objects AN UMa, EF Eri, and E1405-451. Because of the similarities between AM Her and DQ Her objects, it was suggested that such quasi-coherent features might also be found in the DQ Her objects.

Imamura, James N.; Steiman-Cameron, Thomas Y.

1988-01-01

354

Differential CCD photometry of Dubiago, Chiron and Hektor  

NASA Astrophysics Data System (ADS)

Differential CCD photometry of three asteroids, 624 Hektor, 1167 Dubiago and 2060 Chiron, were carried out using the 2.5-m Nordic Optical Telescope on La Palma between March 14-17, 1990. From the resulting light curves, the rotation period of Dubiago was obtained for the first time and found to be 14.3 + or - 0.1 hr, while the previously reported rotation periods for Hektor (6.921 hr) and Chiron (5.92 hr) are consistent with the present results. Light curve amplitudes of 0.22 + or - 0.02 mag for Hektor, 0.23 + or - 0.02 mag for Dubiago, and 0.07 + or - 0.02 mag for Chiron were derived.

Dahlgren, M.; Lagerkvist, C.-I.; Fitzsimmons, A.; Williams, I. P.

1991-05-01

355

CCD photometry of the sparse halo cluster E3  

NASA Astrophysics Data System (ADS)

New photometry in B and V for the sparse halo cluster E3 has been obtained with the prime-focus CCD camera at the CTIO 4-m telescope. The principal sequences are better defined than in the previous color-magnitude (C-M) diagrams, but the large scatter of evolved stars above the turnoff remains. The C-M morphology, inferred old age, and position in the halo definitely indicate that E3 is a globular cluster. Evidence for possible main-sequence binaries appears in the C-M diagram in the form of a sequence parallel to the cluster main sequence and three-quarters of a magnitude above it. The luminosity function drops off sharply about 2.5 mag below the turnoff, supporting the suggestion by van den Bergh, Demers, and Kunkel (1980), that the cluster is severely truncated by tidal forces.

McClure, R. D.; Hesser, J. E.; Stetson, P. B.; Stryker, L. L.

1985-08-01

356

Far-ultraviolet photometry of the globular cluster omega Cen  

NASA Technical Reports Server (NTRS)

We present far-ultraviolet images of the globular cluster omega Centauri obtained with the Ultraviolet Imaging Telescope (UIT) during the 1990 December Astro-1 mission. A total of 1957 sources are detected at 1620 A to a limiting ultraviolet (UV) magnitude of 16.4 in the central 24 min diameter region of the field and a limit of 15.6 over the remainder of the 40 min diameter field. Over 1400 of these sources are matched with stars on a Stroemgren u band charge coupled devices (CCD) frame obtained with the Cerro Tololo Inter-American Observatory (CTIO) 0.9 m telescope to produce a (far-UV, u) color-magnitude diagram (CMD). Completeness of the sample and error estimates are determined by photometry of artificial stars added to the images. The horizontal branch (HB) of the CMD is heavily populated hotter than 9000 K. A large number of 'extreme HB' stars are found hotter than a conspicuous break in the HB at T(sub e) approximately 16000 K. There is also a significant population of stars above the HB, the brightest of which is 4 mag brighter than the HB. Most of the hotter of these appear to be 'AGB-manque' or 'Post-Early Asymptotic Giant Branch' stars. We compare the observations to recent theoretical evolutionary tracks for the zero-age HB and subsequent phases. The tracks match the data well, with the exception of the hotter HB stars, many of which fall below the zero-age horizontal branch. It is unclear as yet whether these are a special population or an artifact of errors in the models or photometry. We identify 33 stars with T(sub e) greater than or approximately = 50000 K, which are hotter than zero-age HB stars with envelope masses of 0.003 solar mass.

Whitney, Jonathan H.; O'Connell, Robert W.; Rood, Robert T.; Dorman, Ben; Landsman, Wayne B.; Cheng, K.-P.; Bohlin, Ralph C.; Hintzen, Paul M. N.; Roberts, Morton S.; Smith, Andrew M.

1994-01-01

357

UV photometry in M2 (NGC 7089) (Lardo+, 2012)  

NASA Astrophysics Data System (ADS)

We present U, V photometry of the globular cluster M2. Stars within 1' and outside of 4' from the cluster center are excluded from the CMD to reduce blending effects and the field star contamination, respectively. We imposed on all stars the selection limits of CHI<2.0 and -1photometry displays an anomalous branch beyond the red edge of the main body of the RGB. The difference in color between stars belonging to this structure and normal RGB stars is quite large (of the order of 0.2-0.3mags, well above the typical measurement errors) and extends down to the SGB region. There may be a second group of stars that are 0.3mags redder with respect to this sequence and can possibly be more, anomalous RGB stars. The observations were carried out during the nights of 2010 July 15 at the Telescopio Nazionale Galileo (TNG) located in La Palma, Canary Islands (Spain), with he DOLORES camera. The DOLORES camera offers a field of view of 8.6'x8.6' with a 0.252"/pix scale. We obtained images of the cluster in the standard Johnson U and V filters for a total of 540s shifted in 3 single exposures in each filter. The seeing condition were average during (~1.2-1.3") during the observing night. (1 data file).

Lardo, C.; Pancino, E.; Mucciarelli, A.; Milone; A. P.

2012-10-01

358

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

359

CCD photometry of distant open clusters. II. NGC 6791.  

NASA Astrophysics Data System (ADS)

Three new photometric CCD-based datasets are presented for NGC 6791. They consist of deep UBV photometry (to V_lim_=24, B_lim_=24, U_lim_=23) of the central parts of the cluster and of selected fields around it, and of relatively shallower UBVI photometry for the whole cluster (23'x23'). The data have been used to discuss the reddening, metallicity and age of NGC 6791, a cluster which is particularly important because of (1) its most-advanced age among open clusters, (2) metallicity higher than solar and (3) particularly large number of member stars. We discovered two new very blue stars increasing the total of sdB objects in the cluster to ten. They are located in a very narrow range magnitudes V=17.7 +/-0.5; their blue colors strongly constrain our determination of the reddening of the cluster to E(B-V)=0.17 +/-0.01. We detected no other blue stars except a population of faint objects with V=~22 in the center of the cluster. Lack of standard data for clusters with metallicity much higher than solar considerably limited the use of the two-color U-B versus B-V diagram to determine metallicity of the cluster. We have used the new theoretical isochrones in a differential determination of metallicity and age of NGC 6791 using M 67 and NGC 188 as two clusters with well-known abundances and age. We find [Fe/H]=~+0.5 and age by 1 Gyr older than that of NGC 188. The luminosity function of the cluster is SURprisingly flat while the "secondary" main-sequence of equal-mass binaries is weaker than in less-populous old open clusters. We explain both features by the large total mass of the cluster which has led to weak evaporation of low-mass and single stars from the cluster.

Kaluzny, J.; Rucinski, S. M.

1995-11-01

360

Glory revealed in disk-integrated photometry of Venus  

NASA Astrophysics Data System (ADS)

Context. Reflected light from a spatially unresolved planet yields unique insight into the overall optical properties of the planet cover. Glories are optical phenomena caused by light that is backscattered within spherical droplets following a narrow distribution of sizes; they are well known on Earth as localised features above liquid clouds. Aims: Here we report the first evidence for a glory in the disk-integrated photometry of Venus and, in turn, of any planet. Methods: We used previously published phase curves of the planet that were reproduced over the full range of phase angles with model predictions based on a realistic description of the Venus atmosphere. We assumed that the optical properties of the planet as a whole can be described by a uniform and stable cloud cover, an assumption that agrees well with observational evidence. Results: We specifically show that the measured phase curves mimic the scattering properties of the Venus upper-cloud micron-sized aerosols, also at the small phase angles at which the glory occurs, and that the glory contrast is consistent with what is expected after multiple scattering of photons. In the optical, the planet appears to be brighter at phase angles of ~11-13° than at full illumination; it undergoes a maximum dimming of up to ~10% at phases in between. Conclusions: Glories might potentially indicate spherical droplets and, thus, extant liquid clouds in the atmospheres of exoplanets. A prospective detection will require exquisite photometry at the small planet-star separations of the glory phase angles. Appendices are available in electronic form at http://www.aanda.org

García Muñoz, A.; Pérez-Hoyos, S.; Sánchez-Lavega, A.

2014-06-01

361

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.

362

Extended Photometry for the DEEP2 Galaxy Redshift Survey: A Testbed for Photometric Redshift Experiments  

NASA Astrophysics Data System (ADS)

This paper describes a new catalog that supplements the existing DEEP2 Galaxy Redshift Survey photometric and spectroscopic catalogs with ugriz photometry from two other surveys: the Canada-France-Hawaii Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs. We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to provide a more uniform data set. We have also used this improved photometry to predict DEEP2 BRI photometry in regions where only poorer measurements were available previously. In addition, we have included improved astrometry tied to SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog contains ~27, 000 objects with full ugriz photometry as well as robust spectroscopic redshift measurements, 64% of which have r > 23. By combining the secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz photometry, we have created a catalog that can be used as an excellent testbed for future photo-z studies, including tests of algorithms for surveys such as LSST and DES.

Matthews, Daniel J.; Newman, Jeffrey A.; Coil, Alison L.; Cooper, Michael C.; Gwyn, Stephen D. J.

2013-02-01

363

Flight investigation on a fighter-type airplane of factors which affect the loads and load distributions on the vertical tail surfaces during rudder kicks and fishtails  

NASA Technical Reports Server (NTRS)

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

Boshar, John

1947-01-01

364

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

PubMed Central

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

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

2011-01-01

365

Time series photometry of the helium atmosphere pulsating white dwarf EC 04207-4748  

NASA Astrophysics Data System (ADS)

We present the analysis of 71 h of high-quality time series CCD photometry of the helium atmosphere pulsating white dwarf (DBV) EC 04207-4748 obtained using the facilities at Mt John University Observatory in New Zealand. The photometric data set consists of four week-long observing sessions covering the period 2011 March to November. A Fourier analysis of the light curves yielded clear evidence of four independent eigenmodes in the star with the dominant mode having a period of 447 s. The light-curve variations exhibit distinct non-sinusoidal shapes, which result in significant harmonics of the dominant frequency appearing in the Fourier transforms. These observed variations are interpreted in terms of non-linear contributions from the energy flux transmission through the sub-surface convection zone in the star. Our modelling of this mechanism, using the methods first introduced by Montgomery, yields a time-averaged convective response time of ?0 ˜ 150 s for the star, and this is shown to be broadly consistent with an MLT/? parameter value between 0.8 and 1.2. It is argued that for the DBV pulsators the measured value of ?0 is a better estimate of the relative stellar surface temperatures than those obtained via spectroscopic techniques.

Chote, P.; Sullivan, D. J.; Montgomery, M. H.; Provencal, J. L.

2013-05-01

366

A Pan-STARRS1-based recalibration of the Sloan Digital Sky Survey photometry  

NASA Astrophysics Data System (ADS)

We present a recalibration of the SDSS DR9 photometry with new flat fields and zero points derived from Pan-STARRS. Using PSF photometry of 60 million stars with 16 < r < 20, we obtain SDSS flat-field and amplifier gain corrections stable to 3 millimagnitudes (mmag) in g,r,i,z bands and 15 mmag in u band. We also identify transient non-photometric periods in SDSS ("contrails") based on photometric deviations co-temporal in SDSS bands. The recalibrated SDSS and PS1 photometry agree with systematics at the 7 mmag level.

Finkbeiner, Douglas P.; Schlafly, E.; Green, G.

2014-01-01

367

THE ARAUCARIA PROJECT. A DISTANCE DETERMINATION TO THE LOCAL GROUP SPIRAL M33 FROM NEAR-INFRARED PHOTOMETRY OF CEPHEID VARIABLES  

SciTech Connect

Motivated by an amazing range of reported distances to the nearby Local Group spiral galaxy M33, we have obtained deep near-infrared photometry for 26 long-period Cepheids in this galaxy with the ESO Very Large Telescope. From the data, we constructed period-luminosity relations in the J and K bands which together with previous optical VI photometry for the Cepheids by Macri et al. were used to determine the true distance modulus of M33, and the mean reddening affecting the Cepheid sample with the multiwavelength fit method developed in the Araucaria Project. We find a true distance modulus of 24.62 for M33, with a total uncertainty of {+-}0.07 mag which is dominated by the uncertainty on the photometric zero points in our photometry. The reddening is determined as E(B - V) = 0.19 {+-} 0.02, in agreement with the value used by the Hubble Space Telescope Key Project of Freedman et al. but in some discrepancy with other recent determinations based on blue supergiant spectroscopy and an O-type eclipsing binary which yielded lower reddening values. Our derived M33 distance modulus is extremely insensitive to the adopted reddening law. We show that the possible effects of metallicity and crowding on our present distance determination are both at the 1%-2% level and therefore minor contributors to the total uncertainty of our distance result for M33.

Gieren, Wolfgang; Pietrzynski, Grzegorz; Graczyk, Dariusz, E-mail: wgieren@astro-udec.cl, E-mail: pietrzyn@hubble.cfm.udec.cl [Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warsaw (Poland); and others

2013-08-10

368

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

369

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

370

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

371

A new look at photometry of the Moon  

NASA Astrophysics Data System (ADS)

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° < ? < 50°, we test two different physical models, macroscopic roughness and multiple scattering between regolith particles, for their ability to quantitatively reproduce the measured radiance difference. Our method for estimating the rms slope angle is unique and model-independent in the sense that the measured radiance factor I/ F at small incidence angles (high Sun) is used as an estimate of I/ F for zero roughness regolith. The roughness is determined from the change in I/ F at larger incidence angles. We determine the roughness for 23 wavelengths from 350 to 939 nm. There is no significant wavelength dependence. The average rms slope angle is 22.2° ± 1.3° for the mare site and 34.1° ± 2.6° for the highland site. These large slopes, which are similar to previous "photometric roughness" estimates, require that sub-mm scale "micro-topography" dominates roughness measurements based on photometry, consistent with the conclusions of Helfenstein and Shepard (Helfenstein, P., Shepard, M.K. [1999]. Icarus 141, 107-131). We then tested an alternative and very different model for the before and after full Moon I/ F variation: multiple scattering within a flat layer of realistic regolith particles. This model consists of a log normal size distribution of spheres that match the measured distribution of particles in a typical mature lunar soil 72141,1 (McKay, D.S., Fruland, R.M., Heiken, G.H. [1974]. Proc. Lunar Sci. Conf. 5, Geochim. Cosmochim. Acta 1 (5), 887-906). The model particles have a complex index of refraction 1.65-0.003 i, where 1.65 is typical of impact-generated lunar glasses. Of the four model parameters, three were fixed at values determined from Apollo lunar soils: the mean radius and width of the log normal size distribution and the real part of the refraction index. We used FORTRAN programs from Mishchenko et al. (Mishchenko, M.I., Dlugach, J.M., Yanovitskij, E.G., Zakharova, N.T. [1999]. J. Quant. Spectrosc. Radiat. Trans. 63, 409-432; Mishchenko, M.I., Travis, L.D., Lacis, A.A. [2002]. Scattering, Absorption and Emission of Light by Small Particles. Cambridge Univ. Press, New York. < http://www.giss.nasa.gov/staff/mmishchenko/books.html>) 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 = 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.

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

2010-08-01

372

Determination of the Components of Reagent and Buffer Solutions by Flame Photometry.  

National Technical Information Service (NTIS)

An analytical process has been worked out for quantitative determination by flame photometry of sodium-potassium tartrate in a Fehling II and Nylander solution, potassium dehydrophosphate, and sodium monohydrophosphate in buffer phosphate solutions used r...

M. Sarsunova S. Szuesova

1971-01-01

373

Narrow-Band Photometry of Comet p/Giacobini-Zinner at the Time of Ice Encounter.  

National Technical Information Service (NTIS)

Narrowband multidiaphragm photometry of comet Giacobini-Zinner, obtained shortly after ICE passed behind the comet's nucleus is summarized. Derived fluxes are presented, and Haser model production rates are given for each night data. The comet appears to ...

C. Sterken J. Manfroid

1987-01-01

374

IRAC Photometry of 400-800K Brown Dwarfs  

NASA Astrophysics Data System (ADS)

Warm IRAC [3.6] and [4.5] photometry is critical for understanding the cold population of brown dwarfs now being found, objects which have more in common with planets than stars. As effective temperature drops from 800K to 400K, the fraction of flux emitted beyond 3um increases rapidly, from about 40% to >75%. This rapid increase makes a color like H-[4.5] a very sensitive temperature indicator, and it can be combined with a gravity and metallicity sensitive color like H-K to constrain all three of these fundamental properties - temperature, gravity and metallicity - which in turn gives us mass and age for these, generally isolated, slowly cooling objects. Our goal is to accurately characterise the temperature/ gravity/ metallicity distribution of the coolest brown dwarfs being found in the UKIRT Infrared Deep Sky Survey (UKIDSS) and the Visible and Infrared Survey Telescope for Astronomy (VISTA), which is only possible if IRAC photometry is available to complement our near-infrared data. While data at similar wavelengths will be provided by WISE for a sample of brown dwarfs, there are large differences between the photometric systems, which will be dependent on metallicity, gravity and the degree of turbulent mixing. Hence to fully exploit the sample of cold T dwarfs found by the near- and mid-infrared sky surveys, and to provide a homogeneous dataset for all ultracool dwarfs, a large number of sources must be observed in both the IRAC and WISE filter sets. Furthermore, different populations will be identified by the different surveys, and the number of cold brown dwarfs will be small, hence IRAC follow- up of UKIDSS, VISTA and WISE brown dwarfs is extremely valuable. The Cycle 8 time will increase the number of 400-600K near-infrared-selected brown dwarf (a sample with mass 5-20 M_Jupiter) that have IRAC data to ~25, a significant increase of ~50%. We expect to trigger eleven low impact ToO observations during Cycle 8, totalling 9.9 hours of AORs.

Leggett, Sandy; Burningham, Ben; Lodieu, Nicolas; Lucas, Phil; Marley, Mark; Pinfield, David; Saumon, Didier; Warren, Steve

2011-05-01

375

Photometry and Spectroscopy of BD+35 1111 in M38  

NASA Astrophysics Data System (ADS)

BD+35 1111 is a ~10.5-magnitude star in the field of M38, an open cluster that has been a target of our ongoing study of H? emission variability in massive stars via narrowband CCD photometry (e.g. Souza, Davis, and Teich 2013, BAAS. 45, PM354.22). BD+35 1111 has no MKK classification in the literature, and is not listed as variable in GCVS, VSX, or NSVS. It is included, with no further characterization, in both the Vatican and Kohoutek catalogs of emission line stars. Using inhomogeneous ensemble photometry (e.g. Bhatti, Richmond, Ford, and Petro 2010, ApJ Supp., 186, 233), we find it to be an irregular variable with a range of ~0.15 mag. To further understand this star we obtained a medium-resolution spectrum using the DIS spectrograph on the ARC 3.5-meter telescope at Apache Point Observatory. We classify BD+35 1111 as B2Ve, the only confirmed Be star in the field of M38. This raises the question of membership, since the age of M38 is likely 250 Ma or greater (Pandey et al. 2007, Publ. Astron. Soc. Japan 59, 547). From published B and V magnitudes we find a nominal distance to BD+35 1111 of 1.6 kpc, but with a range of 1.3 to 2.0 kpc, marginally consistent with distance estimates for M38 ranging from 1.0 to 1.4 kpc. If a member, BD+35 1111 is a candidate blue straggler. If not, it may have escaped from a nearby younger cluster, possibly Kronberger 1 (Kronberger et al. 2006, A&A 447, 921), which has the right heliocentric distance and age. The notion that BD+35 1111 is behind M38 is supported by its reddening of EB-V ~ 0.5, significantly higher than for M38 itself 0.24). We gratefully acknowledge support for student research from NSF grant AST-1005024 to the Keck Northeast Astronomy Consortium, Williams College, and NASA via an American Astronomical Society Small Research Grant.

Souza, Steven P.; Kwitter, Karen B.; Sami, Mona; Beltz-Mohrmann, Gillian

2014-06-01

376

A Scanning Electron and Atomic Force Microscopy Study of the Surface Morphology and Composition of CsI Films as Affected by Evaporation Rate and Humid-Air Exposure  

Microsoft Academic Search

Evaporation rate and subsequent exposure to humid air affect the surface morphology and composition of cesium iodide (CsI) films and, in turn, their photoemissive efficiency when used as photocathodes. The surface morphology and elemental composition of 300-nm-thick CsI films grown at two different rates (1 nm\\/s and 0.04 nm\\/s), both freshly evaporated and after 24-h exposure to humid air were

Giorgio S. Senesi; Mariangela A. Nitti; Antonio Valentini

2005-01-01

377

Surface composition of Pluto  

NASA Technical Reports Server (NTRS)

Broadband (J, H, K and L) and narrowband (1.5- to 3.7-micron) infrared photometry of Pluto has been conducted in order to check previous ambiguous observations of methane frost on the planet's surface. In detail, the match between a laboratory spectrum of methane frost and the observed spectrum of Pluto is not good. Nevertheless, the photometric observations suggest the presence of methane in some form.

Lebofsky, L. A.; Lebofsky, M. J.; Rieke, G. H.

1979-01-01

378

NEOWISE STUDIES OF ASTEROIDS WITH SLOAN PHOTOMETRY: PRELIMINARY RESULTS  

SciTech Connect

We have combined the NEOWISE and Sloan Digital Sky Survey data to study the albedos of 24,353 asteroids with candidate taxonomic classifications derived using Sloan photometry. We find a wide range of moderate to high albedos for candidate S-type asteroids that are analogous to the S complex defined by previous spectrophotometrically based taxonomic systems. The candidate C-type asteroids, while generally very dark, have a tail of higher albedos that overlaps the S types. The albedo distribution for asteroids with a photometrically derived Q classification is extremely similar to those of the S types. Asteroids with similar colors to (4) Vesta have higher albedos than the S types, and most have orbital elements similar to known Vesta family members. Finally, we show that the relative reflectance at 3.4 and 4.6 {mu}m is higher for D-type asteroids and suggest that their red visible and near-infrared spectral slope extends out to these wavelengths. Understanding the relationship between size, albedo, and taxonomic classification is complicated by the fact that the objects with classifications were selected from the visible/near-infrared Sloan Moving Object Catalog, which is biased against fainter asteroids, including those with lower albedos.

Mainzer, A.; Masiero, J.; Bauer, J.; Hand, E. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T.; Mo, W. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Tholen, D. J. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822-1839 (United States); McMillan, R. S.; Maleszewski, C. [Lunar and Planetary Laboratory, University of Arizona, 1629 East University Blvd., Kuiper Space Science Bldg. 92, Tucson, AZ 85721-0092 (United States); Wright, E.; Watkins, J. [UCLA Division of Astronomy and Astrophysics, P.O. Box 91547, Los Angeles, CA 90095-1547 (United States); Spahr, T. [Minor Planet Center, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Cutri, R. M. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Walker, R. [Monterey Institute for Research in Astronomy, Monterey, CA (United States)

2012-01-20

379

ubvy Photometry of magnetic CP stars (Adelman+, 2000)  

NASA Astrophysics Data System (ADS)

Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope (FCAPT) are presented for the magnetic CP stars HD 36668, 36 Lyn, HD 86592, and HR 8861. Using the FCAPT values, North's period for HD 36668 is refined to 2.11884 days. The 3.834 day period of Shore et al. (1990ApJ...348..242S) for 36 Lyn, which was found from magnetic field measurements, is confirmed by photometry. The FCAPT observations also support the 2.8867 day period of Babel & North (1997A&A...325..195B) for HD 86592, demonstrate that this star is a large amplitude variable in v (0.13 mag), and show that y varies crudely out of phase from u, v, and b which are in phase with one another. The variability of HR 8861 appears to be correlated with the meridional passages of regions of Si over- and underabundance as found by Piskunov et al. (1994A&A...291..910P) (5 data files).

Adelman, S. J.

2000-05-01

380

High-speed ultraviolet photometry of HD 60435  

NASA Technical Reports Server (NTRS)

We present the first high-speed ultraviolet photometry of an oscillating Ap star, HD 60435. After removing known orbital effects related to the Hubble Space Telescope, we confirm the presence of a strong pulsation period at a frequency of 123.70 cycles per day. In addition, we find significant amplitude modulation of this frequency that we suggest could be the result of beating of multiple periodicities. In this context, we suggest evidence for the presence of four additional frequencies at nu = 120.56, 126.55, 149.49, and 221.03 cycles per day. Three of these frequencies correspond well to frequencies detected in optical observations of HD 60435. The fourth, at 149.49 cycles per day, if real, is a potentially new pulsation mode that has not been detected in ground-based observations of this star. The amplitude of the 123 cycles per day pulsation is significantly larger in the ultraviolet than it is in the blue.

Taylor, M.; Nelson, M. J.; Bless, R. C.; Dolan, J. F.; Elliot, J. L.; Percival, J. W.; Robinson, E. L.; Van Citters, G. W.

1993-01-01

381

BVI CCD Photometry of the Globular Cluster 47Tuc  

NASA Astrophysics Data System (ADS)

We present BVI photometry for about 16000 stars from a 220 square arcmin field centered 8arcmin East of the center of 47 Tuc. We have identified eight likely blue stragglers located in the outer parts of the cluster. Four of these objects are easy targets for spectroscopic studies with ground-based telescopes. Six candidates for blue horizontal branch stars were identified. However, it is possible that all or most of them belong in fact to the SMC halo. One faint blue star being candidate for a cataclysmic variable was found close to the cluster center. The average I-band magnitude for stars forming the red giant branch clump is determined at I_0=13.09+/-0.005 mag. This in turn implies distance modulus of the cluster (m-M)_{0,47Tuc}=13.32+/-0.03+/-0.036 mag (statistical plus systematic error), if we adopt M_{I,m}=-0.23+/-0.03 mag for the average absolute luminosity of Hipparcos-calibrated clump giants, following Paczynski and Stanek and Stanek and Garnavich. This distance modulus of 47 Tuc is lower by 0.2-0.25 mag than its recent estimates based on Hipparcos parallaxes for subdwarfs. We discuss possible reasons for this discrepancy. The photometric data are available through the anonymous ftp service.

Kaluzny, J.; Wysocka, A.; Stanek, K. Z.; Krzeminski, W.

1998-09-01

382

GASPS Photometry of the Tucana-Horologium Association  

NASA Technical Reports Server (NTRS)

The GASPS Open Time Key Programme on Herschel represents a new opportunity to sensitively probe protoplanetary and debris disks at far-IR wavelengths. We present preliminary PACS 70 and 160 micron photometry of eighteen stars in the 30 Myr-old Tucana-Horologium association. Of these eighteen, eight were detected in the 70 micron band. Four of these eight were also detected in the 160 micron band. We constructed SEDs for these systems using optical data from Hipparcos (B and V), near-IR data from 2MASS (J, H, and K), mid-IR data from IRAS and Spitzer MIPS (12 and 24 microns, respectively), and the new far-IR data from PACS. For the stars showing IR excess emission, we fit simple single-temperature blackbody curves to the IR excess in order to determine the rough dust abundances and temperatures. Dust observations at these wavelengths will also be important for comparison with upcoming Herschel PACS spectra that will search for gas in the disks. Our goal is to determine or limit the ever-allusive gas-to-dust ratio for these disk systems.

Roberge, Donaldson J.; Roberge, Aki

2010-01-01

383

Determining thallium in semiconductor crystals by solvent extraction and photometry  

SciTech Connect

Promising optoelectronic materials are represented by single crystals of compounds in the systems TlX-Ge (Sn, Pb, Cd)X/sub 2/, where X is Cl, Br, or I. To choose growth conditions for good crystals, one needs information on the uniformity of the thallium distributions. Solvent extraction followed by photometry is widely used, which is based on extracting ionic associated groups (IA) such as thallium(III) halide complexes formed with basic dyes. They have devised a selective and reliable method of determining thallium by the use of the cyanin dye cation rose 2C (CR 2C). Thallium(III) forms ionic associates with CR 2C in sulfuric acid in the presence of bromide, which can be extracted by aromatic hydrocarbons and by alkyl acetates. They established the optimum conditions for the formation and extraction of the IA by varying the acidity, the bromide concentration, and the CR 2C concentration, as well as the contact time and the volume ratio between the aqueous and organic phases.

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

1987-08-01

384

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

385

UBVI CCD Photometry of the Old Open Cluster Berkeley 17  

NASA Astrophysics Data System (ADS)

Photometric UBVI CCD photometry is presented for NGC 188 and Berkeley 17. Color-magnitude diagrams (CMDs) are constructed and reach well past the main-sequence turnoff for both clusters. Cluster ages are determined by means of isochrone fitting to the cluster CMDs. These fits are constrained to agree with spectroscopic metallicity and reddening estimates. Cluster ages are determined to be 7.0+/-0.5 Gyr for NGC 188 and 10.0+/-1.0 Gyr for Berkeley 17, where the errors refer to uncertainties in the relative age determinations. These ages are compared to the ages of relatively metal-rich inner halo/thick-disk globular clusters and other old open clusters. Berkeley 17 and NGC 6791 are the oldest open clusters, with ages of 10 Gyr. They are 2 Gyr younger than the thick-disk globular clusters. These results confirm the status of Berkeley 17 as one of the oldest known open clusters in the Milky Way, and its age provides a lower limit to the age of the Galactic disk.

Krusberg, Zosia A. C.; Chaboyer, Brian

2006-03-01

386

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

387

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

388

RELATIVE PHOTOMETRY OF HAT-P-1b OCCULTATIONS  

SciTech Connect

We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of two occultations of the transiting exoplanet HAT-P-1b. By measuring the planet to star flux ratio near opposition, we constrain the geometric albedo of the planet, which is strongly linked to its atmospheric temperature gradient. An advantage of HAT-P-1 as a target is its binary companion ADS 16402 A, which provides an excellent photometric reference, simplifying the usual steps in removing instrumental artifacts from HST time-series photometry. We find that without this reference star, we would need to detrend the lightcurve with the time of the exposures as well as the first three powers of HST orbital phase, and this would introduce a strong bias in the results for the albedo. However, with this reference star, we only need to detrend the data with the time of the exposures to achieve the same per-point scatter, therefore we can avoid most of the bias associated with detrending. Our final result is a 2{sigma} upper limit of 0.64 for the geometric albedo of HAT-P-1b between 577 and 947 nm.

Beky, Bence; Holman, Matthew J.; Noyes, Robert W.; Sasselov, Dimitar D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Gilliland, Ronald L. [Center for Exoplanets and Habitable Worlds, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Bakos, Gaspar A. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544 (United States); Winn, Joshua N., E-mail: bbeky@cfa.harvard.edu [Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139 (United States)

2013-06-01

389

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

390

Photometry of FK Com for 1993-2001 (Korhonen+, 2001)  

NASA Astrophysics Data System (ADS)

We report 8 years of previously unpublished photometric observations of FK Com. The observations have been carried out between 1993 and 2001 with six different telescopes: 60 cm at Mt. Maidanak (Tashkent, Uzbekistan), Phoenix 10, Wolfgang and Amadeus located in Arizona, USA, and 20cm and 60 cm KVA on La Palma, Spain. Observations contain measurements at the following bands: Johnson U, B, V and R, Bessel R, Cousins I and Stromgren b and y. The observations are differential photometry in respect to the primary comparison star HD 117567. NOTE: Table 1 in the paper contains some small misprints in the Julian dates. Also for Wolfgang and Amadeus the number of observations given in Table1 at each band is slightly less than actually given in Table2c and Table2d. This is caused by accidentally using a limiting error of 0.01 in magnitudes when creating Table 1. In Table 2 the limiting error for Wolfgang and Amadeus is 0.02 mag, as mentioned in the paper itself. In Table2a-e 99.0000 means that no observations were available at that time at that band or that the error in the magnitude was larger than 0.02. (5 data files).

Korhonen, H.; Berdyugina, S. V.; Tuominen, I.; Andersen, M. I.; Piironen, J.; Strassmeier, K. G.; Grankin, K. N.; Kaasalainen, S.; Karttunen, H.; Mel'Nikov, S. Yu.; Shevchenko, V. S.; Trisoglio, M.; Virtanen, J.

2001-07-01

391

Infrared photometry of the black hole candidate Sagittarius A*  

NASA Technical Reports Server (NTRS)

An infrared source has been imaged within 0.2 +/- 0.3 arcseconds of the unique Galactic center radio source Sgr A* High angular resolution (averaged value of the Full Width at Half Maximum (FWHM) approximately 0.55 arcseconds) was achieved by rapid (approximately 50 Hz) real-time images motion compensation. The source's near-infrared magnitudes (K = 12.1 +/- 0.3, H = 13.7 +/- 0.3, and J = 16.6 +/- 0.4) are consistent with a hot object reddened by the local extinction A(sub v) approximately 27). At the 3 sigma level of confidence, a time series of 80 images limits the source variability to less than 50% on timescales from 3 to 30 minutes. The photometry is consistent with the emission from a simple accretion disk model for a approximately 1 x 10(exp 6) solar mass black hole. However, the fluxes are also consistent with a hot luminous (L approximately 10(exp 3.5) to 10(exp 4-6) solar luminosity) central cluster star positionally coincident with Sgr A*.

Close, Laird M.; Mccarthy, Donald W. JR.; Melia, Fulvio

1995-01-01

392

Worldwide photometry of the January 1989 Tau Persei eclipse  

NASA Astrophysics Data System (ADS)

New UBV photoelectric photometry of Tau Persei obtained at 19 different observatories during its recent January 1989 eclipse is presented. Mideclipse occurred at JD 2 447 542.31 + or - 0.01. The resulting light curve, though not complete at all phases, is solved for the elements with the help of two quantities derived from spectroscopy: the eclipse is 84 percent total at mideclipse, and the ratio of the radii is 0.135 + or - 0.01. Radii relative to the semimajor axis are 0.0236 for the G5 giant and 0.0032 for the A2 star. With a reasonable total mass assumed, the absolute radii say the A2 star could be luminosity class V or somewhat evolved and the G5 star is between III and II but could be closer to II. The G5 giant is brighter than the A2 star by 1.72 mag in V and the color excess in B - V is 0.06 mag, both quantities consistent (within uncertainties) with earlier estimates of Ake (1986). The eclipse duration, from first to fourth contact, is 2.09 day. The orbital inclination is 88.74 deg, consistent with what McAlister derived from speckle interferometry. Because of the large (e = 0.73) eccentricity, there is no secondary eclipse at all.

Hall, Douglas S.; Barksdale, William S.; Curott, David R.; Diethelm-Sutter, Roger; Ells, Jack; Frey, Gary J.; Houchen, Michael B.; Krisciunas, Kevin; Leiker, P. Steven; Lines, Helen C.; Lines, Richard D.; Miles, Richard; Milton, Russell E.; Ohshima, Osamu; Powell, Harry D.; Pasour, John L.; Schroder, Klaus-Peter; Slauson, Douglas M.; Smith, Diane Pyper; Snyder, Leroy F.; Williams, David B.

1991-05-01

393

Far-ultraviolet stellar photometry: A field in Orion  

NASA Astrophysics Data System (ADS)

Far-ultraviolet photometry for 625 objects in Orion is presented. These data were extracted from electrographic camera images obtained during sounding rocket flights in 1975 and 1982. The 1975 images were centered close to the belt of Orion while the 1982 images were centered approximately 9 deg further north. One hundred and fifty stars fell in the overlapping region and were observed with both cameras. Sixty-eight percent of the objects were tentatively identified with known stars using the SIMBAD database while another 24% are blends of objects too close together to separate with our resolution. As in previous studies, the majority of the identified ultraviolet sources are early-type stars. However, there are a significant number for which no such identification was possible, and we suggest that these are interesting objects which should be further investigated. Seven stars were found which were bright in the ultraviolet but faint in the visible. We suggest that some of these are nearby white dwarfs.

Schmidt, Edward G.; Carruthers, George R.

1993-12-01

394

An Evaluation of Loading Rate of Dust, Pb, Cd, and Ni and Metals Mass Concentration in the Settled Surface Dust in Domestic Houses and Factors Affecting Them  

Microsoft Academic Search

Interior and exterior measurements of surface loading rates for settled surface dust in domestic houses and the content of three metals — lead (Pb), cadmium (Cd) and nickel (Ni) — were conducted weekly during the autumn of 2007 in an urban area of Giza, Egypt. Surface mass concentrations of the metals were also calculated. Results revealed that the interior and

M. I. Khoder; S. K. Hassan; A. A. El-Abssawy

2010-01-01

395

A Scanning Electron and Atomic Force Microscopy Study of the Surface Morphology and Composition of CsI Films as Affected by Evaporation Rate and Humid-Air Exposure  

NASA Astrophysics Data System (ADS)

Evaporation rate and subsequent exposure to humid air affect the surface morphology and composition of cesium iodide (CsI) films and, in turn, their photoemissive efficiency when used as photocathodes. The surface morphology and elemental composition of 300-nm-thick CsI films grown at two different rates (1 nm/s and 0.04 nm/s), both freshly evaporated and after 24-h exposure to humid air were investigated by means of atomic force microscopy and scanning electron microscopy/electron diffraction spectroscopy. The CsI film freshly evaporated at a slow rate exhibited a granular surface presenting circular holes or craters where the CsI material was moved from the center to the boundaries. After 24-h exposure to humid air, this film coalesced in large grain showing a marked increase of surface roughness. Conversely, the CsI film grown at a fast rate mostly retained its original surface uniformity and homogeneity with no presence of holes and craters after 24-h exposure to humid air. Further, surface roughness and average peak height decreased, but the surface coalesced in large grains spaced by small fractures where the CsI coverage was almost lost. In conclusion, the films grown at a fast evaporation rate were affected by 24-h exposure to humid air less than those grown at a slow rate, and are thus expected to possess a greater long-term stability.

Senesi, Giorgio S.; Nitti, Mariangela A.; Valentini, Antonio

2005-04-01

396

A scanning electron and atomic force microscopy study of the surface morphology and composition of CsI films as affected by evaporation rate and humid-air exposure.  

PubMed

Evaporation rate and subsequent exposure to humid air affect the surface morphology and composition of cesium iodide (CsI) films and, in turn, their photoemissive efficiency when used as photocathodes. The surface morphology and elemental composition of 300-nm-thick CsI films grown at two different rates (1 nm/s and 0.04 nm/s), both freshly evaporated and after 24-h exposure to humid air were investigated by means of atomic force microscopy and scanning electron microscopy/electron diffraction spectroscopy. The CsI film freshly evaporated at a slow rate exhibited a granular surface presenting circular holes or craters where the CsI material was moved from the center to the boundaries. After 24-h exposure to humid air, this film coalesced in large grain showing a marked increase of surface roughness. Conversely, the CsI film grown at a fast rate mostly retained its original surface uniformity and homogeneity with no presence of holes and craters after 24-h exposure to humid air. Further, surface roughness and average peak height decreased, but the surface coalesced in large grains spaced by small fractures where the CsI coverage was almost lost. In conclusion, the films grown at a fast evaporation rate were affected by 24-h exposure to humid air less than those grown at a slow rate, and are thus expected to possess a greater long-term stability. PMID:15817141

Senesi, Giorgio S; Nitti, Mariangela A; Valentini, Antonio

2005-04-01

397

Documentation for the machine-readable version of the ANS Ultraviolet Photometry Catalogue of Point Sources (Wesselius et al 1982)  

NASA Technical Reports Server (NTRS)

The machine-readable version of the Astronomical Netherlands Satellite ultraviolet photometry catalog is described in detail, with a byte-by-byte format description and characteristics of the data file given. The catalog is a compilation of ultraviolet photometry in five bands, within the wavelength range 155 nm to 330 nm, for 3573 mostly stellar objects. Additional cross reference data (object identification, UBV photometry and MK spectral types) are included in the catalog.

Warren, W. H., Jr.

1984-01-01

398

Star Formation History of NGC 1311 from Multiwavelength Stellar Photometry  

NASA Astrophysics Data System (ADS)

NGC 1311 is a nearby (D = 5.5 Mpc), but little studied, late-type spiral (SBm). It has been observed with HST/WFPC2 (F300W, F606W and F814W) and NICMOS (NIC3 F160W) as part of a program to build a multiwavelength imaging database of nearby galaxies. This allows for the study of the resolved stellar population from 2900 Angstroms to 1.6 microns. Color-magnitude and color-color diagrams of the resolved stars show clear evidence for hot main-sequence stars with ages of 10s of Myr, and cooler evolved stars with ages of 100s of Myr. Analysis of the photometry of the candidate star clusters suggests that NGC 1311 had an earlier star and cluster forming episode 1 Gyr ago or more. This is consistent with observational work on other nearby low-luminosity galaxies indicating a bursting mode of star-formation. The recent star formation, as traced by the NUV continuum, is concentrated at the east and west ends of the central bulge-like concentration. This is reminiscent of stochastic star formation models as well as the observed properties of other low-luminosity star-forming galaxies (e.g., Sextans A). NGC 1311 is an excellent example of a nearby, low-luminosity, star-forming, gas-rich galaxy that is evolving in relative isolation. Understanding the star- and cluster-formation history and chemical evolution of such galaxies is an essential part of unraveling the problem of galaxy evolution. This work is supported by NASA Hubble Space Telescope grants HST-GO-09124* and HST-GO-09824*.

Eskridge, Paul B.

2007-12-01

399

SECONDARY ECLIPSE PHOTOMETRY OF WASP-4b WITH WARM SPITZER  

SciTech Connect

We present photometry of the giant extrasolar planet WASP-4b at 3.6 and 4.5 {mu}m taken with the Infrared Array Camera on board the Spitzer Space Telescope as part of Spitzer's extended warm mission. We find secondary eclipse depths of 0.319% {+-} 0.031% and 0.343% {+-} 0.027% for the 3.6 and 4.5 {mu}m bands, respectively, and show model emission spectra and pressure-temperature profiles for the planetary atmosphere. These eclipse depths are well fit by model emission spectra with water and other molecules in absorption, similar to those used for TrES-3 and HD 189733b. Depending on our choice of model, these results indicate that this planet has either a weak dayside temperature inversion or no inversion at all. The absence of a strong thermal inversion on this highly irradiated planet is contrary to the idea that highly irradiated planets are expected to have inversions, perhaps due the presence of an unknown absorber in the upper atmosphere. This result might be explained by the modestly enhanced activity level of WASP-4b's G7V host star, which could increase the amount of UV flux received by the planet, therefore reducing the abundance of the unknown stratospheric absorber in the planetary atmosphere as suggested in Knutson et al. We also find no evidence for an offset in the timing of the secondary eclipse and place a 2{sigma} upper limit on |ecos {omega}| of 0.0024, which constrains the range of tidal heating models that could explain this planet's inflated radius.

Beerer, Ingrid M.; Knutson, Heather A. [Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720 (United States); Burrows, Adam [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 05844 (United States); Fortney, Jonathan J.; Laughlin, Gregory [Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Agol, Eric; Cowan, Nicolas B. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Charbonneau, David; Desert, Jean-Michel [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Deming, Drake [Planetary Systems Laboratory, NASA's Goddard Space Flight Center, Greenbelt MD 20771 (United States); Langton, Jonathan [Department of Physics, Principia College, Elsah, IL 62028 (United States); Lewis, Nikole K.; Showman, Adam P. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

2011-01-20

400

Just the Photometry: Constraining exoplanet orbits by measuring stellar densities  

NASA Astrophysics Data System (ADS)

One unique trick in toolkit of astronomers studying transiting exoplanets, is that the mean stellar density may be determined using the shape of the light curve, under various idealized assumptions such as a circular orbit and the target star is unblended. “Asterodensity profiling” seeks to exploit this trick by comparing the light curve derived stellar density to that from some independent measurement. Any difference between the two measures indicates that one or more of the idealized assumptions are invalid. Therefore, the major challenge with single-planet systems (so-called “single-body asterodensity profiling” or SAP) is distinguishing whether the difference is due to a blend, orbital eccentricity or some combination. By careful consideration of the input priors, utilizing constraints from secondary eclipses and a Bayesian analysis of the system in question, the problem is tractable though, offering the chance to determine the underlying eccentricity distribution of exoplanets and even aid in validating planet candidates through blend analysis. In this talk, I will discuss single-body asterodensity profiling (SAP) for targets with asteroseismologically determined stellar densities, which is generally considered a gold-standard measure. We have investigated several targets with the largest apparent discrepancies between the transit-derived stellar density and that from asteroseismology. By independently detrending and fitting the transit light curves, we have calculated a revised value of this crucial ratio, with various priors tried. I will present the current results our work and discuss implications for the eccentricity and blend validation of these studied systems. I will finish by exploring the exciting potential of this technique in the TESS-era, where the fact our technique requires bright-star photometry alone, opens the door to constraints for hundreds/thousands of objects.

Sliski, David; Kipping, D. M.

2014-01-01

401

Near-Infrared Absolute Photometry of the Saturnian Satellites  

NASA Astrophysics Data System (ADS)

We report absolutely-calibrated photometry of the Saturnian satellites in canonical near-infrared filters, including the first such spectrum of the leading side of Enceladus. The satellites were observed during Ring Plane Crossing in August and September of 1995 with the NSFCAM instrument at the NASA/IRTF. These observations were also simultaneous with those of the Uranian system, taken with the same instrument and filters, and analyzed by Baines et al. (Icarus 132, 266-284, 1998). Results are reported for J, H, and K filters near 1.27, 1.62, and 2.20 mu m, and two 0.1 mu m-wide filters centered at 1.73 and 2.27 mu m. We find that Enceladus has a peak brightness at 1.27 mu m with a geometric albedo of 0.898 +/- 0.063, in contrast to the Uranian satellites Miranda, Ariel, and Titania, which are relatively dim at this wavelength (albedos of roughly 0.3). The J-H band depth of Enceladus is about 30%, characteristic of spectra of Rhea, Tethys, and the trailing side of Iapetus, taken from Clark et al. (Icarus 58, 265-281, 1984) and convolved with our filters. By contrast, the darker Uranian satellites display a J-H band depth of less than 10%. From H to 1.73 mu m, the full-disk albedo of Enceladus increases by 27%, similar to the Uranian satellites. The dip in the Enceladus spectrum from J to H, as well as the subsequent rise from H to 1.73 mu m, are an expected signature of water ice. Finally, preliminary results for the albedos of Tethys, Dione, Rhea, and Mimas, as well as Enceladus, at 2.27 mu m compare favorably with the visible albedos of Buratti and Veverka (Icarus, 58, 254-264, 1984).

Momary, T. W.; Baines, K. H.; Yanamandra-Fisher, P. A.; Lebofsky, L. A.; Golisch, W.; Kaminski, C.

1998-09-01

402

Improved mm-wave photometry for kinetic inductance detectors  

NASA Astrophysics Data System (ADS)

Context. We have developed a dual-band (140 and 220 GHz) mm-wave imaging camera based on superconducting kinetic inductance detector (KID) arrays. Each array contains 132 superconducting resonators whose resonant frequencies are shifted by mm-wave photons absorption. The read out is achieved with a single electronics chain per band, taking advantage of the intrinsic KID frequency-domain multiplexability. The arrays are easily scalable and well adapted for future large format focal plane instruments. NIKA (formerly Néel IRAM KID Array, now New IRAM KID Array) has been specifically designed for the IRAM 30 m telescope at Pico Veleta, and is one of the first instruments using KIDs to have made measurements of astronomical sources. Aims: In this Letter we describe the solutions adopted to improve the calibration accuracy and the sensitivity of the instrument, and we report on the outcome of the 3rd NIKA observing run of October, 2011. Methods: We use a fast electronic modulation of the readout tone for each KID pixel in order to linearize the instrument calibration, which we track with measurements of planets. We also adopt a new design of the KIDs, sensitive to both polarizations, to increase the amount of radiation absorbed and thus the optical efficiency of the system. Results: We measured an average sensitivity on the sky of 21 mJys0.5 per beam at 140 GHz and 140 mJys0.5 at 220 GHz in the best observing conditions (?220 ? 0.2) after atmospheric noise decorrelation. The sensitivity at 220 GHz was limited by the atmospheric attenuation and loading as well as a reduction in the spectral bandwidth due to a misplaced filter. We found the repeatability in the photometry over the entire observing run to be better than 10% in both bands, thus demonstrating a significant improvement over the previous runs. We also find good agreement between NIKA measurements of faint astronomical sources and previous measurements of the same sources.

Calvo, M.; Roesch, M.; Désert, F.-X.; Monfardini, A.; Benoit, A.; Mauskopf, P.; Ade, P.; Boudou, N.; Bourrion, O.; Camus, P.; Cruciani, A.; Doyle, S.; Hoffmann, C.; Leclercq, S.; Macias-Perez, J. F.; Ponthieu, N.; Schuster, K. F.; Tucker, C.; Vescovi, C.

2013-03-01

403

Aperture Photometry Tool Versus SExtractor for Noncrowded Fields  

NASA Astrophysics Data System (ADS)

Outputs from new software program Aperture Photometry Tool (APT) are compared with similar outputs from SExtractor for sources extracted from R-band optical images acquired by the Palomar Transient Factory (PTF), infrared mosaics constructed from Spitzer Space Telescope images, and a processed visible/near-infrared image from the Hubble Legacy Archive (HLA). Two large samples from the PTF images are studied, each containing around 3×103 sources from noncrowded fields. The median values of source-intensity relative percentage differences between the two software programs, computed separately for two PTF samples, are +0.13% and +0.17%, with corresponding statistical dispersions of 1.43% and 1.84%, respectively. For the Spitzer mosaics, a similar large sample of extracted sources for each of channels 1--4 of Spitzer''s Infrared Array Camera (IRAC) are analyzed with two different sky annulus sizes, and we find that the median and modal values of source-intensity relative percentage differences between the two software programs are between -0.5% and +2.0%, and the corresponding statistical dispersions range from 1.4 to 6.7%, depending on the Spitzer IRAC channel and sky annulus. The results for the HLA image are mixed, as might be expected for a moderately crowded field. The comparisons for the three different kinds of images show that there is generally excellent agreement between APT and SExtractor. Differences in source-intensity uncertainty estimates for the PTF images amount to less than 3% for the PTF sources, and these are potentially caused by SExtractor''s omission of the sky background uncertainty term in the formula for source-intensity uncertainty, as well as differing methods of sky background estimation.

Laher, Russ R.; Rebull, Luisa M.; Gorjian, Varoujan; Masci, Frank J.; Fowler, John W.; Grillmair, Carl; Surace, Jason; Mattingly, Sean; Jackson, Ed; Hacopeans, Eugean; Hamam, Nouhad; Groom, Steve; Teplitz, Harry; Mi, Wei; Helou, George; van Eyken, Julian C.; Law, Nicholas M.; Dekany, Richard G.; Rahmer, Gustavo; Hale, David; Smith, Roger; Quimby, Robert M.; Ofek, Eran O.; Kasliwal, Mansi M.; Zolkower, Jeff; Velur, Viswa; Walters, Richard; Henning, John; Bui, Khahn; McKenna, Dan; Kulkarni, Shrinivas R.

2012-07-01

404

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

405

Open Cluster Survey: Time-Series Monitoring and Precise Photometry  

NASA Astrophysics Data System (ADS)

Star clusters, especially compact ones (with diameter of few to ten arcmin), are suitable targets to search for light variability in a group of stars by means of an ordinary Cassegrain telescope plus CCD system. A special patrolling with short time-fixed exposures and mmag accuracy could be used also to study stellar oscillation for a group of stars simultaneously. The last can be carried out both separately from one site and within the WET(Whole-Earth Telescope) XCov campaigns. The detection of extra-solar planet transit events might be a by-product of a long-term monitoring of compact open clusters as well. We present the program of open star clusters monitoring with the Zeiss 1 meter RCC telescope of Maidanak observatory which has been recently automated. In combination with quite good seeing at this observatory (see, e.g., Sarazin, M. 1999, URL http://www.eso.org/gen-fac/pubs/astclim/) the automatic telescope, equipped with a large-format (2KX2K) CCD camera AP-10, will allow collecting homogeneous time-series for analysis. We already started this program in 2001 and had a set of patrol observations with a Zeiss 0.6 meter telescope and an AP-10 camera in 2003. Seven compact open clusters in the Milky Way (NGC 7801, King 1, King 13, King 8, King 20, Berkeley 55, IC 4996) have been monitored for stellar variability and some results of photometry will be presented. A few interesting variables were discovered and dozens for the moment are suspected of variability for the first time within our program. It is also shown how observations like these could feasibly be used for exo-planet searches. We have made steps to join the Whole-Earth Telescope effort in future campaigns for Asteroseismology.

Hojaev, A. S.; Semakov, D. G.

2006-08-01

406

GSC04778-00152 photometry and spectroscopy (Tuvikene+, 2008)  

NASA Astrophysics Data System (ADS)

CCD photometry of GSC04778-00152 was carried out on 54 nights during 9 observing runs. In January 2006 the observations were made with the 41-cm Meade telescope at Observatorio Cerro Armazones (OCA), Chile, using an SBIG STL-6303E CCD camera (3072x2048 pixels, FOV 23.0'x15.4') and Johnson V filter. On 3 nights in December 2006 and on 2 nights in October 2007 we used the 2.4-m Hiltner telescope at the MDM Observatory, Arizona, USA, equipped with the 8kx8k Mosaic imager (FOV 23.6'x23.6'). In December 2006 and January 2007, we also used the 41-cm Meade telescope at OCA, using an SBIG ST-7XME CCD camera (FOV 5.9'x3.9') with no filter. Figure 3 shows all OCA light curves obtained with this configuration. At Tartu Observatory the observations were carried out in December 2006 and January 2007, using the 60-cm telescope with a SpectraSource Instruments HPC-1 camera (1024x1024 pixels, FOV 11.2'x11.2') and V filter. >From January to March 2007 the system was observed using the 1.0-m telescope at SAAO, Sutherland, South Africa with an STE4 CCD camera (1024x1024 pixels, FOV 5.3'x5.3') and UBVRI filters. Spectroscopic observations were carried out at the Tartu Observatory, Estonia, using the 1.5-m telescope with the Cassegrain spectrograph ASP-32 and an Andor Newton CCD camera. (3 data files).

Tuvikene, T.; Sterken, C.; Eenmae, T.; Hinojosa-Goni, R.; Brogt, E.; Longa Pena, P.; Liimets, T.; Ahumada, M.; Troncoso, P.; Vogt, N.

2012-04-01

407

Strömgren photometry in globular clusters: M55 & M22  

NASA Astrophysics Data System (ADS)

We present Strömgren CCD photometry for the two galactic globular clusters M55 (NGC 6809) and M22 (NGC 6656). We find average Strömgren metallicities of -1.71+/- 0.04 dex for M55 and -1.62+/- 0.08 dex for M22. The determination of metal abundances in cluster giants with the Strömgren m_1 index in comparison with spectroscopic data from Briley et al. (1993) and Norris & Freeman (1982, 1983) shows that M55 and M22 have different distributions of cyanogen strengths. In M55, no CN abundance variations are visible among the giant-branch stars. In striking contrast, a large dispersion of cyanogen strengths is seen in M22. For M22 we find patchily distributed variations in the foreground reddening of Delta E(B-V) ~ 0.07, which explain the colour dispersion among the giant-branch stars. There is no evidence for a spread in iron within M22 since the variations in m_1 are dominated by the large range in CN abundances, as already found by Anthony-Twarog et al. (1995). The difference between M55 and M22 may resemble the difference in integral CN band strength between M31 globular clusters and the galactic system. The colour-magnitude diagram of M55 shows the presence of a population of 56 blue-straggler stars that are more centrally concentrated than the red giant-branch stars. Based on data collected at the European Southern Observatory, La Silla, Chile

Richter, P.; Hilker, M.; Richtler, T.

1999-10-01

408

All-sky uvby photometry of speckle binaries (Sowell+ 1993)  

NASA Astrophysics Data System (ADS)

Binary stars play an important role in determining several key stellar physical parameters. The most fundamental quantity is stellar mass, which in order to be determined, requires knowledge of the orbital period and semi-major axis of the system. Unfortunately, the majority of visual binaries have orbital periods on the order of many decades, making complete cycles difficult to obtain during the lifetime of a single observer. The application of speckle interferometry has greatly improved the situation, for now hundreds of binary systems with periods on the order of ten years or less, are routinely observed, especially by astronomers at the Center for High Angular Resolution Astronomy (CHARA) at Georgia State University (McAlister & Hartkopf 1988). In conjunction with the appropriate spectroscopic data, precise ``visual'' orbits for these speckle binaries (Hartkopf et al 1989) will provide accurate masses for a wide range of spectral types.A second vital characteristic is intrinsic luminosity. This boundary condition is necessary for both stellar interior and evolutionary models. The CHARA speckle program recognized the need for luminosity information to complement astrometry observations. Accurate photometry, unlike astrometry, requires only a few observations of the system, unless a member is variable. Algorithms to extract luminosity ratios from the speckle data have been developed. Although the techniques are still limited (e.g., non-calibrated), previous ``speckle photometry'' results have been reported by Bagnuolo & Sowell (1988) and Bagnuolo & Hartkopf (1989) for Capella and by Dombrowski (1990) for several Hyades stars.The purpose of this observing program was to obtain accurate uvby photometry of a large set of speckle binaries discovered or frequently observed by CHARA. Knowing the integrated magnitude and the ratio of the luminosities at selected wavelengths provides sufficient information to solve for the intrinsic brightness and color of each component. When combined with the masses from the ongoing speckle astrometry program, these stars will be important calibrators of the mass--luminosity relationship. Visually unresolved binaries have usually been omitted from photometric programs. Most of the program stars are bright, and one would have expected them to be well observed. However, many were known to be visually unresolved or marginally resolved binaries; hence, these systems were often deleted from previous photometric programs. OBSERVATIONS The photoelectric observations were obtained during 1989 November 11 to 17 (by J.W.W.) and during 1991 April 24 to 30 (by J.R.S.). In both cases the Automated Filter Photometer was used on a 36-inch telescope at KPNO. The same 1P21 phototube and uvby filter set were used on the two runs, as was a 15 arcsec diaphragm. Standard deadtime corrections and sky subtraction procedures were applied (Henden & Kaitchuck 1982). The transformation equations are listed below: V(std) = epsilony [(b-y)(std)] + zetay + (y - kappa'_y X) (1) (b-y)(std) = epsilonb-y [ (b-y) - kappa' b-y X ] + zeta_b-y (2) m1(std) = epsilonm1 [ m1 - kappa' m1 X ] + zetam1 (3) c1(std) = epsilonc1 [ c1 - kappa' c1 X ] + zetac1 (4) The extinction, transformation, and zero point coefficients were determined nightly; these coefficients are listed in Table 1. The extinction, transformation, and zero point coefficients were determined nightly; these coefficients are listed in Table 1. Standard stars were taken from Perry et al (1987). Gronbech et al (1976) divided their standard stars (i.e., transformation equations) into two groups, with the division at b-y = 0.410. Olsen (1983) used three groups, for he subdivided the cooler standards into evolved and unevolved sets. We used only one set of standard stars and transformation equations for the following reason. The majority of our program speckle binaries were believed a priori to be unevolved B, A, F, or G stars. This assumption was due to the observational constraint that, in order to be resolved by speckle interferometry, the magnitude differ

Sowell, J. R.; Wilson, J. W.

1993-04-01

409

Hubble Space Telescope Photometry for the Halo Stars in the Leo Elliptical NGC 3377  

NASA Astrophysics Data System (ADS)

We have used the ACS camera on HST to obtain (V,I) photometry for 57,000 red giant stars in the halo of the Leo elliptical NGC 3377, an intermediate-luminosity elliptical. We use this sample of stars to derive the metallicity distribution function (MDF) for its halo field stars and comment on its chemical evolution history compared with both larger and smaller E galaxies. Our ACS WFC field spans a radial range extending from 4 to 18 kpc projected distance from the center of NGC 3377 and thus covers a significant portion of this galaxy's halo. We find that the MDF is broad, reaching a peak at log(Z/Zsolar)~=-0.6, but containing virtually no stars more metal-poor than log(Z/Zsolar)=-1.5. It may, in addition, have relatively few stars more metal-rich than log(Z/Zsolar)~=-0.3, although interpretation of the high-metallicity end of the MDF is limited by photometric completeness that affects the detection of the reddest, most metal-rich stars. NGC 3377 appears to have an enrichment history intermediate between those of normal dwarf ellipticals and the much larger giants. As yet, we find n