Corneal hysteresis is correlated with reduction in axial length after trabeculectomy.

BACKGROUND: We sought to determine whether corneal biomechanical parameters are predictive of reduction in axial length after anti-metabolite trabeculectomy. METHODS: Chinese subjects undergoing trabeculectomy with mitomycin C by a single experienced surgeon underwent the following measurements: Corneal hysteresis (CH, Ocular Response Analyzer, Reichert Ophthalmic Instruments), Goldmann intra-ocular pressure (IOP), central corneal thickness (CCT) and axial length (AL, IOLMaster, Carl Zeiss Meditec, Dublin, CA) were measured pre-operatively, and AL, CH and IOP were measured 1 day and 1 week post-operatively. RESULTS: Mean age of 31 subjects was 52.0 ± 15.2 years, and 15 (48.4%) were female. The mean pre-operative IOP of 21.4 ± 9.3 mmHg was reduced to 8.2 ± 4.6 mmHg 1 day and 11.0 ± 4.4 mmHg 1 week post-operatively (p < 0.001). AL declined from 22.99 ± 0.90 to 22.76 ± 0.87 mm at 1 day and 22.74 ± 0.9 mm at 1 week; 30/31 (%) eyes had a decline in AL (p < 0.001, sign test). In multivariate linear regression models including post-operative data from 1 day and 1 week, greater decline in Goldmann IOP (p < 0.0001, greater pre-op axial length (p < 0.001) and lower pre-operative CH (p = 0.03), were all associated with greater decline in post-operative axial length. CONCLUSIONS: Eyes with lesser ability of the ocular coat to absorb energy (lower CH) had significantly greater decrease in axial length after trabeculectomy-induced IOP-lowering.

Transverse Spreading of Electrons in High-Intensity Laser Fields

We show that for collisions of electrons with a high-intensity laser, discrete photon emissions introduce a transverse beam spread that is distinct from that due to classical (or beam shape) effects. Via numerical simulations, we show that this quantum induced transverse momentum gain of the electron is manifest in collisions with a realistic laser pulse of intensity within reach of current technology, and we propose it as a measurable signature of strong-field quantum electrodynamics.

Gamma-ray Spectra and Enhancement Factors for Positron Annihilation with Core Electrons

Many-body theory is developed to calculate the γ spectra for positron annihilation in noble-gas atoms. Inclusion of electron-positron correlation effects and core annihilation gives spectra in excellent agreement with experiment [K. Iwata et al., Phys. Rev. Lett. 79, 39 (1997)]. The calculated correlation enhancement factors γnl for individual electron orbitals nl are found to scale with the ionization energy I_nl (in eV), as γnl=1+ √A/Inl+(B/I_nl)β, where A≈40  eV, B≈24  eV, and β≈2.3.

Measurement of Fast Electrons Spectra Generated by Interaction between Solid Target and Peta Watt Laser

Fast electron energy spectra have been measured for a range of intensities between 1018 Wcm−2 and 1021 Wcm−2 and for different target materials using electron spectrometers. Several experimental campaigns were conducted on peta watt laser facilities at the Rutherford Appleton Laboratory and Osaka University. In these experimental campaigns, the pulse duration was varied from 0.5 ps to 5 ps. The laser incident angle was also changed from normal incidence to 40° in p-polarized. The results show a reduction from the ponderomotive scaling on fast electrons over 1020 Wcm−2.

Extreme-Ultraviolet-Initated High-Order Harmonic Generation: Driving Inner-Valence Electrons Using Below-Threshold-Energy Extreme-Ultraviolet Light

We propose a novel scheme for resolving the contribution of inner- and outer-valence electrons in XUV-initiated high-harmonic generation in neon. By probing the atom with a low energy (below the 2s ionisation threshold) ultrashort XUV pulse, the 2p electron is steered away from the core, while the 2s electron is enabled to describe recollision trajectories. By selectively suppressing the 2p recollision trajectories we can resolve the contribution of the 2s electron to the high-harmonic spectrum. We apply the classical trajectory model to account for the contribution of the 2s electron, which allows for an intuitive understanding of the process.

Continuous flow gas phase photoreforming of methanol at elevated reaction temperatures sensitised by Pt/TiO2

Gas phase photoreforming of methanol using a Pt/TiO2 photocatalyst has been performed under flow conditions at elevated temperatures. Comparing the activity of the reforming process as a function of temperature under dark and irradiated conditions shows a significant enhancement in the rate of H2 production using the photo-assisted conditions at temperatures between 100-140 °C. At higher temperatures, the effect of irradiation is small with the process dominated by the thermal process. Deactivation of the catalyst was observed under irradiation but the catalyst was easily regenerated using an oxygen treatment at 120 °C. Diffuse Reflectance Infra-red Fourier Transform Spectroscopy (DRIFTS) showed that the activity of the catalyst could be correlated with the presence of the photogenerated trapped electrons. In addition, lower amounts of CO adsorbed on Pt, compared to those observed in the dark reaction, were found for the UV-irradiated systems. It is proposed that CO and adsorbed intermediates, such as formate, can act as inhibitors in the photoreforming process and this is further supported by the observation that, before and after the regeneration process in O2, the CO and surface adsorbed organic intermediate products are removed and the activity is recovered.