Now showing items 1640-1659 of 1673

    • The WARPS survey. VII. The WARPS-II cluster catalog 

      Horner, Donald J.; Perlman, Eric S.; Ebeling, Harald; Jones, Laurence R.; Scharf, Caleb A.; Wegner, Gary A.; Malkan, Matthew A.; Maughan, Ben J. (2008-06)
      We present the galaxy cluster catalog from the second, larger phase of the Wide Angle ROSAT Pointed Survey (WARPS), an X-ray selected survey for high-redshift galaxy clusters. WARPS is among the largest deep X-ray cluster ...
    • Waveguide delivery of x-rays for minimally invasive tumor therapy 

      Waynant, Ronald W.; Ilev, Ilko K.; Kunal, Mitra (2001-05-21)
      We are studying the potential use of x-rays, which are collected by non-imaging optics and delivered through stereotactically guided needles by hollow waveguides, for irradiation of tumors. X-rays have greater transparency ...
    • Wavelength independency of spatially multiplexed communication channels in standard multimode optical fibers 

      Murshid, Syed H.; Lovell, Gregory L.; Hridoy, Arnob; Parhar, Gurinder; Chakravarty, Abhijit; Alanzi, Saud F.; Chowdhury, Bilas (2016-08-08)
      Spatial domain multiplexing (SDM), also known as space division multiplexing, adds a new degree of photon freedom to existing optical fiber multiplexing techniques by allocating separate radial locations to different ...
    • Wavelength specific fluorescence coefficients for simulating hyperspectral reflectance signatures of water 

      Bostater, Charles R.; Rebman, Jan (1999-12-17)
      A model which describes the transfer of irradiant light in water is used to predict the fluorescence response of the water surface reflectance under solar induced or an artificial light source such as a laser. Formulations ...
    • Wavelet based image compression using perceptual distortion metric 

      Goswami, Hemen; Kozaitis, S.P. (2003-08-08)
      Bits are allocated to various subbands to minimize a particular cost function to achieve compression in subband coding. The most common cost function is the L2 norm based on mean squared error (MSE). However, the MSE often ...
    • Wavelet-based fusion approach using unique reconstruction approach 

      Ouendeno, Michel; Kozaitis, Samuel P. (2007-04-09)
      We used measures based on entropy to evaluate a method designed to fuse imagery from different sensor types. The method uses different forward transforms of input images and a common transform to reconstruct the final ...
    • Wavelet-based image compression using randomized quantization 

      Kozatis, Samuel Peter; Goswami, Hemen (2000-06-29)
      We applied dithered quantization to image compression using a wavelet transform, scalar quantization method. The results indicate that dithered quantization could change the noise characteristics ofthe reconstructed image.
    • Wavelet-based noise reduction in multispectral imagery 

      Basuhail, Abdullah A.; Kozaitis, S.P. (1998-07-02)
      We used a 3-D wavelet-based denoising method to reduce the noise from multispectral imagery. In our approach, we compared denoising of different bands of a multispectral image using a 2-D denoising technique, by which the ...
    • The WEBT campaign on the blazar 3C 279 in 2006 

      Böttcher, Markus; Basu, Shantanu; Joshi, Manasvita; Villata, Massimo; Arai, Akira; Aryan, N.; Asfandiyarov, I. M.; Bach, Uwe; Robertson, Jeff W.; Vennes, Stéphane (2007-12-01)
      The quasar 3C 279 was the target of an extensive multiwavelength monitoring campaign from 2006 January through April. An optical-IR-radio monitoring campaign by the Whole Earth Blazar Telescope (WEBT) collaboration was ...
    • Weighted Composition Operators From Logarithmic Bloch-Type Spaces To Bloch-Type Spaces 

      Stevic, Stevo; Agarwal, Ravi P. (2009-07-03)
      The boundedness and compactness of the weighted composition operators from to Bloch-type spaces are studied here. © 2009 S. Stević and R. P. Agarwal.
    • Where Are the Magnetic White Dwarfs with Detached, Nondegenerate Companions? 

      Liebert, James W.; Wickramsinghe, Dayal T.; Schmidt, Gary D.; Silvestri, Nicole M.; Hawley, Suzanne L.; Szkody, Paula; Ferrario, Lilia; Webbink, Ronald F.; Oswalt, T. D.; Smith, Jonathan Allyn (2005-05)
      The Sloan Digital Sky Survey has already more than doubled the sample of white dwarfs with spectral classi- fications, the subset with detached M dwarf companions, and the subset of magnetic white dwarfs. In the course ...
    • White dwarf cosmochronometry. I. Monte Carlo simulations of proper-motion and magnitude-limited samples using Schmidt's 1/Vmax estimator 

      Wood, Matt A.; Oswalt, T. D. (1998-04-20)
      Observationally, white dwarf stars are a remarkably homogeneous class with a minimum observed Teff ∼ 4000 K. Theoretically, the physics that determines their cooling timescales is relatively more straightforward than that ...
    • White dwarfs in common proper motion binary systems: Mass distribution and kinematics 

      Silvestri, Nicole M.; Oswalt, T. D.; Wood, Matt A.; Smith, Jonathan Allyn; Reid, Iain Neill; Sión, Edward M. (2001-01)
      We present the mass distribution, gravitational redshifts, radial velocities, and space motions of white dwarf stars in common proper motion binary systems. The mass distribution we derive for the 41 DA white dwarfs in ...
    • White dwarfs in globular clusters: Hubble space telescope observations of M4 

      Richer, Harvey B.; Fahlman, Gregory G.; Ibata, Rodrigo A.; Pryor, Carlton; Bell, Roger A.; Bolte, Michael S.; Bond, Howard E.; Harris, William E.; Hesser, James E.; Wood, Matt A. (1997-08-01)
      Using WFPC2 on the Hubble Space Telescope, we have isolated a sample of 258 white dwarfs (WDs) in the Galactic globular cluster M4. Fields at three radial distances from the cluster center were observed, and sizable WD ...
    • The white dwarfs within 20 parsecs of the sun: Kinematics and statistics 

      Sión, Edward M.; Holberg, Jay B.; Oswalt, T. D.; McCook, George P.; Wasatonic, Richard P. (2009-12)
      We present the kinematical properties, distribution of spectroscopic subtypes, and stellar population subcomponents of the white dwarfs within 20 pc of the Sun. We find no convincing evidence of halo white dwarfs in the ...
    • The white dwarfs within 25 pc of the sun: Kinematics and spectroscopic subtypes 

      Sión, Edward M.; Holberg, Jay B.; Oswalt, Terry D.; McCook, George P.; Wasatonic, Richard P.; Myszka, Janine (2014-05-01)
      We present the fractional distribution of spectroscopic subtypes, range and distribution of surface temperatures, and kinematical properties of the white dwarfs (WDs) within 25 pc of the Sun. There is no convincing evidence ...
    • Whole Earth Telescope discovery of a strongly distorted quadrupole pulsation in the largest amplitude rapidly oscillating Ap star 

      Holdsworth, Daniel L.; Kurtz, Donald W.; Saio, Hideyuki; Provençal, Judith L.; Letarte, Bruno; Sefako, Ramotholo R.; Petit, Véronique; Smalley, Barry; Thomsen, H.; Fletcher, C. L. (2018-01-01)
      We present a new analysis of the rapidly oscillating Ap (roAp) star, 2MASS J19400781 - 4420093 (J1940; V = 13.1). The star was discovered using SuperWASP broad-band photometry to have a frequency of 176.39 d-1 (2041.55 ...
    • Whole earth telescope observations of the helium interacting binary PG 1346+082 (CR Bootis) 

      Provençal, Judith L.; Winget, Don Earl; Nather, R. Edward; Robinson, Edward L.; Clemens, J. Christopher; Bradley, Paul A.; Claver, Charles F.; Kleinman, Scot J.; Grauer, Albert D.; Wood, Matt A. (1997-05-01)
      We present our analysis of 240 hr of white-light, high-speed photometry of the dwarf nova-like helium variable PG 1346+082 (CR Boo). We identify two frequencies in the low-state power spectrum, at 679.670 ± 0.004 μHz and ...
    • Whole earth telescope observations of the pulsating subdwarf B Star PG 0014+067 

      Vučković, Maja; Kawaler, Steven D.; O'Toole, Simon J.; Csubry, Zoltán; Baran, Andrzej S.; Zoła, Stanislaw; Moskalik, Paweł A.; Klumpe, Eric W.; Wood, Matt A.; Wilkat, V. (2006-08-01)
      PG 0014+067 is one of the most promising pulsating subdwarf B stars for seismic analysis, as it has a rich pulsation spectrum. The richness of its pulsations, however, poses a fundamental challenge to understanding the ...
    • Whole Earth telescope observations of the ZZ Ceti star HL Tau 76 

      Dolez, Noël; Vauclair, Gérard P.; Kleinman, Scot J.; Chevreton, M.; Fu, Jianning; Solheim, Jan Erik; Pérez, Jaime M González; Wood, Matt A.; Ahrens, Thomas J.; Silvestri, Nicole M. (2006-01)
      This paper analyses the Whole Earth Telescope observations of HL Tau 76, the first discovered pulsating DA white dwarf. The star was observed during two Whole Earth Telescope campaigns. It was a second priority target ...