Skip to main content

Research Repository

Advanced Search

All Outputs (19)

The cosmology of the Fab-Four (2012)
Journal Article
Copeland, E. J., Padilla, A., & Saffin, P. M. (2012). The cosmology of the Fab-Four. Journal of Cosmology and Astroparticle Physics, 2012(12), Article 026. https://doi.org/10.1088/1475-7516/2012/12/026

We have recently proposed a novel self tuning mechanism to alleviate the famous cosmological constant problem, based on the general scalar tensor theory proposed by Horndeski. The self-tuning model ends up consisting of four geometric terms in the ac... Read More about The cosmology of the Fab-Four.

Nonlinear modal coupling in a high-stress doubly-clamped nanomechanical resonator (2012)
Journal Article
Lulla, K., Cousins, R., Venkatesan, A., Patton, M., Armour, A., Mellor, C. J., & Owers-Bradley, J. (2012). Nonlinear modal coupling in a high-stress doubly-clamped nanomechanical resonator. New Journal of Physics, 14, Article 113040. https://doi.org/10.1088/1367-2630/14/11/113040

We present results from a study of the nonlinear inter-modal coupling between different flexural vibrational modes of a single high-stress, doubly-clamped silicon nitride nanomechanical beam. Using the magnetomotive technique and working at 100 mK we... Read More about Nonlinear modal coupling in a high-stress doubly-clamped nanomechanical resonator.

Calibrated BOLD using direct measurement of changes in venous oxygenation (2012)
Journal Article
Driver, I. D., Hall, E. L., Wharton, S. J., Pritchard, S. E., Francis, S. T., & Gowland, P. A. (2012). Calibrated BOLD using direct measurement of changes in venous oxygenation. NeuroImage, 63(3), https://doi.org/10.1016/j.neuroimage.2012.08.045

Calibration of the BOLD signal is potentially of great value in providing a closer measure of the underlying changes in brain function related to neuronal activity than the BOLD signal alone, but current approaches rely on an assumed relationship bet... Read More about Calibrated BOLD using direct measurement of changes in venous oxygenation.

Prospects for detecting the 21 cm forest from the diffuse intergalactic medium with LOFAR (2012)
Journal Article
Ciardi, B., Labropoulos, P., Maselli, A., Thomas, R., Zaroubi, S., Graziani, L., …Yatawatta, S. (2013). Prospects for detecting the 21 cm forest from the diffuse intergalactic medium with LOFAR. Monthly Notices of the Royal Astronomical Society, 428(2), 1755-1765. https://doi.org/10.1093/mnras/sts156

We discuss the feasibility of the detection of the 21 cm forest in the diffuse intergalactic medium (IGM) with the radio telescope LOFAR. The optical depth to the 21 cm line has been derived using simulations of reionization which include detailed ra... Read More about Prospects for detecting the 21 cm forest from the diffuse intergalactic medium with LOFAR.

Fiber orientation-dependent white matter contrast in gradient echo MRI (2012)
Journal Article
Wharton, S., & Bowtell, R. W. (2012). Fiber orientation-dependent white matter contrast in gradient echo MRI. Proceedings of the National Academy of Sciences, 109(45), https://doi.org/10.1073/pnas.1211075109

Recent studies have shown that there is a direct link between the orientation of the nerve fibers in white matter (WM) and the contrast observed in magnitude and phase images acquired using gradient echo MRI. Understanding the origin of this link is... Read More about Fiber orientation-dependent white matter contrast in gradient echo MRI.

The covariance of multi-field perturbations, pseudo-susy and fNL (2012)
Journal Article
Saffin, P. M. (2012). The covariance of multi-field perturbations, pseudo-susy and fNL. Journal of Cosmology and Astroparticle Physics, 2012(9), Article 002. https://doi.org/10.1088/1475-7516/2012/09/002

We reconsider cosmological perturbation theory for multi-component scalars, enforcing covariance in field-space, and ensuring that phyical observations are independent of field re-definitions. We use the formalism to clarify some issues in the litera... Read More about The covariance of multi-field perturbations, pseudo-susy and fNL.

The intergalactic medium thermal history at redshift z = 1.7–3.2 from the Lyα forest: a comparison of measurements using wavelets and the flux distribution (2012)
Journal Article
Garzilli, A., Bolton, J., -S. Kim, T., Leach, S., & Viel, M. (2012). The intergalactic medium thermal history at redshift z = 1.7–3.2 from the Lyα forest: a comparison of measurements using wavelets and the flux distribution. Monthly Notices of the Royal Astronomical Society, 424(3), 1723-1736. https://doi.org/10.1111/j.1365-2966.2012.21223.x

We investigate the thermal history of the intergalactic medium (IGM) in the redshift interval z = 1.7–3.2 by studying the small-scale fluctuations in the Lyman α forest transmitted flux. We apply a wavelet filtering technique to 18 high-resolution qu... Read More about The intergalactic medium thermal history at redshift z = 1.7–3.2 from the Lyα forest: a comparison of measurements using wavelets and the flux distribution.

Manifestation of dynamic Jahn-Teller distortions and surface interactions in scanning tunnelling microscopy images of fullerene anion C?60 (2012)
Journal Article
Dunn, J. L., Lakin, A. J., & Hands, I. D. (2012). Manifestation of dynamic Jahn-Teller distortions and surface interactions in scanning tunnelling microscopy images of fullerene anion C?60. New Journal of Physics, 14, Article 083038. https://doi.org/10.1088/1367-2630/14/8/083038

Using scanning tunnelling microscopy (STM), it is possible to observe detailed structure of the molecular orbitals (MOs) of fullerene anions C−60. However, understanding the experimental observations is not straightforward because of the inherent pre... Read More about Manifestation of dynamic Jahn-Teller distortions and surface interactions in scanning tunnelling microscopy images of fullerene anion C?60.

Scanning capacitance imaging of compressible and incompressible quantum Hall effect edge strips (2012)
Journal Article
Suddards, M., Baumgartner, A., Henini, M., & Mellor, C. J. (2012). Scanning capacitance imaging of compressible and incompressible quantum Hall effect edge strips. New Journal of Physics, 14, Article 08315. https://doi.org/10.1088/1367-2630/14/8/083015

We use dynamic scanning capacitance microscopy to image compressible and incompressible strips at the edge of a Hall bar in a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime. This method gives access to the complex local c... Read More about Scanning capacitance imaging of compressible and incompressible quantum Hall effect edge strips.

Classical duals, Legendre transforms and the Vainshtein mechanism (2012)
Journal Article
Padilla, A., & Saffin, P. M. (2012). Classical duals, Legendre transforms and the Vainshtein mechanism. Journal of High Energy Physics, 2012(7), Article 122. https://doi.org/10.1007/JHEP07%282012%29122

We show how to generalize the classical duals found by Gabadadze {et al} to a very large class of self-interacting theories. This enables one to adopt a perturbative description beyond the scale at which classical perturbation theory breaks down in t... Read More about Classical duals, Legendre transforms and the Vainshtein mechanism.

The effect of intergalactic helium on hydrogen reionization: implications for the sources of ionizing photons at z>6 (2012)
Journal Article
Ciardi, B., Bolton, J., Maselli, A., & Graziani, L. (2012). The effect of intergalactic helium on hydrogen reionization: implications for the sources of ionizing photons at z>6. Monthly Notices of the Royal Astronomical Society, 423(1), 558-574. https://doi.org/10.1111/j.1365-2966.2012.20902.x

We investigate the effect of primordial helium on hydrogen reionization using a hydrodynamical simulation combined with the cosmological radiative transfer code CRASH. The radiative transfer simulations are performed in a 35.12 h−1 comoving Mpc box u... Read More about The effect of intergalactic helium on hydrogen reionization: implications for the sources of ionizing photons at z>6.

Self-tuning and the derivation of a class of scalar-tensor theories (2012)
Journal Article
Charmousis, C., Copeland, E. J., Padilla, A., & Saffin, P. M. (2012). Self-tuning and the derivation of a class of scalar-tensor theories. Physical Review D, 85(10), Article 104040. https://doi.org/10.1103/PhysRevD.85.104040

We have recently proposed a special class of scalar tensor theories known as the Fab Four. These arose from attempts to analyse the cosmological constant problem within the context of Horndeski's most general scalar tensor theory. The Fab Four togeth... Read More about Self-tuning and the derivation of a class of scalar-tensor theories.

The Lyman α forest flux probability distribution at z>3 (2012)
Journal Article
Calura, F., Tescari, E., D’Odorico, V., Viel, M., Cristiani, S., Kim, T., & Bolton, J. (2012). The Lyman α forest flux probability distribution at z>3. Monthly Notices of the Royal Astronomical Society, 422(4), 3019-3036. https://doi.org/10.1111/j.1365-2966.2012.20811.x

We present a measurement of the Lyman α flux probability distribution function (PDF) obtained from a set of eight high-resolution quasar spectra with emission redshifts in the range 3.3 ≤z≤ 3.8. We carefully study the effect of metal absorption lines... Read More about The Lyman α forest flux probability distribution at z>3.

Dynamical simulations of electroweak baryogenesis with fermions (2012)
Journal Article
Saffin, P. M., & Tranberg, A. (2012). Dynamical simulations of electroweak baryogenesis with fermions. Journal of High Energy Physics, 2012(2), Article 102. https://doi.org/10.1007/JHEP02%282012%29102

We perform real-time numerical lattice simulations of a one-family version of the Standard Model. We model the quantum fermions using the ensemble method and treat the bosonic scalar and non-abelian gauge fields classically. Our main interest is elec... Read More about Dynamical simulations of electroweak baryogenesis with fermions.

General second-order scalar-tensor theory and self-tuning (2012)
Journal Article
Charmousis, C., Copeland, E. J., Saffin, P. M., & Padilla, A. (2012). General second-order scalar-tensor theory and self-tuning. Physical Review Letters, 108(5), Article 051101. https://doi.org/10.1103/PhysRevLett.108.051101

Starting from the most general scalar-tensor theory with second order field equations in four dimensions, we establish the unique action that will allow for the existence of a consistent self-tuning mechanism on FLRW backgrounds, and show how it can... Read More about General second-order scalar-tensor theory and self-tuning.

Improved measurements of the intergalactic medium temperature around quasars: possible evidence for the initial stages of He-II reionisation at z~6 (2012)
Journal Article
S. Bolton, J., D. Becker, G., Raskutti, S., Stuart B. Wyithe, J., G. Haehnelt, M., & L. W. Sargent, W. (2012). Improved measurements of the intergalactic medium temperature around quasars: possible evidence for the initial stages of He-II reionisation at z~6. Monthly Notices of the Royal Astronomical Society, 419(4), 2880–2892. https://doi.org/10.1111/j.1365-2966.2011.19929.x

We present measurements of the intergalactic medium (IGM) temperature within ~5 proper Mpc of seven luminous quasars at z~6. The constraints are obtained from the Doppler widths of Lyman-alpha absorption lines in the quasar near-zones and build upon... Read More about Improved measurements of the intergalactic medium temperature around quasars: possible evidence for the initial stages of He-II reionisation at z~6.

Magnetic field effects on the vestibular system: calculation of the pressure on the cupula due to ionic current-induced Lorentz force (2012)
Journal Article
Antunes, A., Glover, P., Li, Y., Mian, O., & Day, B. (2012). Magnetic field effects on the vestibular system: calculation of the pressure on the cupula due to ionic current-induced Lorentz force. Physics in Medicine and Biology, 57(14), https://doi.org/10.1088/0031-9155/57/14/4477

Large static magnetic fields may be employed in magnetic resonance imaging (MRI). At high magnetic field strengths (usually from about 3 tesla and above) it is possible for humans to perceive a number of effects. One such effect is mild vertigo. Rece... Read More about Magnetic field effects on the vestibular system: calculation of the pressure on the cupula due to ionic current-induced Lorentz force.

A novel receive-only liquid nitrogen (LN2)-cooled RF coil for high-resolution in vivo imaging on a 3-Tesla whole-body scanner (2012)
Journal Article
Hu, B., Varma, G., Randell, C., Keevil, S. F., Schaeffter, T., & Glover, P. (2012). A novel receive-only liquid nitrogen (LN2)-cooled RF coil for high-resolution in vivo imaging on a 3-Tesla whole-body scanner. IEEE Transactions on Instrumentation and Measurement, 61(1), https://doi.org/10.1109/TIM.2011.2157575

The design and operation of a receive-only liquid nitrogen (LN2)-cooled coil and cryostat suitable for medical imaging on a 3-T whole-body magnetic resonance scanner is presented. The coil size, optimized for murine imaging, was determined by using... Read More about A novel receive-only liquid nitrogen (LN2)-cooled RF coil for high-resolution in vivo imaging on a 3-Tesla whole-body scanner.