Keck constraints on a varying fine-structure constant: wavelength calibration errors (2009)
Murphy, Michael T., Webb, John K., Flambaum, Victor V.
The Keck telescope's HIRES spectrograph has previously provided evidence for a smaller fine-structure constant, alpha, compared to the current laboratory value, in a sample of 143 quasar absorption...
King, Julian A., Mortlock, Daniel J., Webb, John K., Murphy, Michael T.
Recent attempts to constrain cosmological variation in the fine structure constant, alpha, using quasar absorption lines have yielded two statistical samples which initially appear to be...
Stringent null constraint on cosmological evolution of the proton-to-electron mass ratio (2008)
King, Julian A., Webb, John K., Murphy, Michael T., Carswell, Robert F.
We present a strong constraint on variation of the proton-to-electron mass ratio, mu, over cosmological time scales using molecular hydrogen transitions in optical quasar spectra. Using high quality...
Stringent null constraint on cosmological evolution of the proton-to-electron mass ratio (2008)
King, Julian A., Webb, John K., Murphy, Michael T., Carswell, Robert F.
We present a strong constraint on variation of the proton-to-electron mass ratio mu over cosmological time scales using molecular hydrogen transitions in optical quasar spectra. Using high quality...
Murphy, Michael T., Webb, John K., Flambaum, Victor V.
In their Letter [Phys. Rev. Lett. 92, 121302 (2004)] (also [Astron. Astrophys. 417, 853 (2004)]), Srianand et al. analysed optical spectra of heavy-element species in 23 absorption systems along...
Revision of VLT/UVES constraints on a varying fine-structure constant (2006)
Murphy, Michael T., Webb, John K., Flambaum, Victor V.
We critically review the current null results on a varying fine-structure constant, alpha, derived from VLT/UVES quasar absorption spectra, focusing primarily on the many-multiplet analysis of 23...
Grivas, Theodoros B, Burwell, Geoffrey R, Vasiliadis, Elias S, Webb, John K
Abstract Background The role of rib cage in the development of progressive infantile idiopathic scoliosis (IIS) has not been studied previously. No report was found for rib growth in children with...
Cosmological Evolution of Heavy Element and Molecular Hydrogen Abundances (2003)
Curran, Stephen J., Webb, John K., Murphy, Michael T., Carswell, Robert F.
Spectroscopic observations of distant quasars have resulted in the detection of molecular hydrogen in intervening damped Lyman-alpha absorption clouds (DLAs). We use observations compiled from...
The Deuterium Abundance in the z=0.7 absorber towards QSO PG1718+4807 (2003)
Crighton, Neil H. M., Webb, John K., Carswell, Robert F., Lanzetta, Ken M.
We report a further analysis of the ratio of deuterium to hydrogen (D/H) using HST spectra of the z=0.701 Lyman limit system towards the QSO PG1718+481. Initial analyses of this absorber found it...
Davis, Tamara M., Lineweaver, Charles H., Webb, John K.
We use the dynamics of a galaxy, set up initially at a constant proper distance from an observer, to derive and illustrate two counter-intuitive general relativistic results. Although the galaxy does...
Davis, Tamara M., Lineweaver, Charles H., Webb, John K.
We use the dynamics of a galaxy, set up initially at a constant proper distance from an observer, to derive and illustrate two counter-intuitive general relativistic results. Although the galaxy does...
Sengupta, Dilip K, Mehdian, SMH, Mulholland, Robert C, Webb, John K, Ohnmeiss, Donna D
Abstract Background Recent cadaver studies show stability against axial rotation with a cylindrical cage is marginally superior to a rectangular cage. The purpose of this biomechanical study in...
Pascarelle, Sebastian M., Lanzetta, Kenneth M., Chen, Hsiao-Wen, Webb, John K.
We present an analysis of galaxy and QSO absorption line pairs toward 24 QSOs at redshifts between z~0.2 and 1 in an effort to establish the relationship between galaxies and absorption lines in...
Chen, Hsiao-Wen, Lanzetta, Kenneth M., Webb, John K., Barcons, Xavier
(Abridged) We present results of a program to obtain and analyze HST WFPC2 images and ground-based images of galaxies identified in an imaging and spectroscopic survey of faint galaxies in fields of...
The Origin of C IV Absorption Systems at Redshifts z (2001)
Chen, Hsiao-Wen, Lanzetta, Kenneth M., Webb, John K.
(Abridged) We report the discovery of extended CIV gaseous envelopes around galaxies of a wide range of luminosity and morphological type. First, we show that CIV absorption systems are strongly...
Davis, Tamara M., Lineweaver, Charles H., Webb, John K.
We use the dynamics of a galaxy, set up initially at a constant proper distance from an observer, to derive and illustrate two counter-intuitive general relativistic results. Although the galaxy does...
Webb, John K., Wormleaton, Imma
Although the extra-solar planets discovered so far are of the giant, gaseous, type, the increased sensitivity of future surveys will result in the discovery of lower mass planets. The detection of O2...
Constraints on the Unseen Galaxy Population from the Lyman-alpha Forest (1998)
Lanzetta, Kenneth M., Chen, Hsiao-Wen, Webb, John K., Barcons, Xavier
Here we describe results of our attempt to determine what types of galaxies are responsible for the Lyman-alpha forest absorption systems, based on our ongoing imaging and spectroscopic survey of...
Evaluation of Auxiliary Tracker Approach to Solving the EED Problem at Robins AFB, Georgia. (1998)
Stockdale, Thomas C., Webb, John K., Feldman, H., Luke, Daniel W.
Since the onset of operations of the PAVE PAWS radar at Robins AFB in Georgia, concerns have been raised regarding a possible safety hazard to aircraft due to the proximity of the radar to the...
Environmental Dependence of the Nature of Gaseous Envelopes of Galaxies at z < 1 (1998)
Yahata, Noriaki, Lanzetta, Kenneth M., Webb, John K., Barcons, Xavier
We present new statistical study on the origin of Lyman-alpha absorption systems that are detected in QSO fields. The primary objective is to investigate environmental dependence of the relationship...
Observations of QSO J2233-606 in the Southern Hubble Deep Field (1998)
Sealey, Katrina M., Drinkwater, Michael J., Webb, John K.
The Hubble Deep Field South (HDF-S) HST observations are expected to begin in October 1998. We present a composite spectrum of the QSO in the HDF-S field covering UV/optical/near IR wavelengths,...
The Hubble Deep Field-South QSO (1998)
Sealey, Katrina M., Drinkwater, Michael. J., Webb, John K., Boyle, Brian J.
The Hubble Deep Field-South (HDF-S) was chosen to have a QSO (RA 22:33:37.6 Dec -60:33:29 J2000 and B=17.5) in the field to allow for studies of absorption systems intersecting the sight line to the...
A Search for Time Variation of the Fine Structure Constant (1998)
Webb, John K., Flambaum, Victor V., Churchill, Christopher W., Drinkwater, Michael J., Barrow, John D.
A method offering an order of magnitude sensitivity gain is described for using quasar spectra to investigate possible time or space variation in the fine structure constant, alpha. Applying the...
The Galaxy-Absorber Cross-Correlation Function (1997)
Lanzetta, Kenneth M., Webb, John K., Barcons, Xavier
We describe an analysis of the galaxy-absorber cross-correlation function as a function of velocity separation, impact parameter separation, and absorber Lyman alpha equivalent width on impact...
Is there a role for selective anterior instrumentation in neuromuscular scoliosis?
Tokala, Devi Prakash, Lam, Khai S., Freeman, Brian J.C., Webb, John K.
Our objective was to report on the clinical and radiological outcome from a cohort of patients with neuromuscular scoliosis who underwent selective anterior single rod instrumentation for correction...
C7 decancellisation closing wedge osteotomy for the correction of fixed cervico-thoracic kyphosis
Tokala, Devi Prakash, Lam, Khai S., Freeman, Brian J.C., Webb, John K.
Our objective is to report on the clinical and radiological outcome following a decancellisation closing wedge osteotomy for the correction of fixed cervico-thoracic kyphosis in patients with...
Behensky, Hannes, Cole, Ashley A., Freeman, Brian J.C., Grevitt, Michael P., Mehdian, Hossein S., Webb, John K.
Retrospective radiographic review of surgically treated double major curves (Lenke type 3C) in adolescent idiopathic scoliosis. To evaluate the role of selective posterior thoracic correction and...