Physics
http://hdl.handle.net/10468/224
2017-01-24T01:13:14ZThe kynurenine pathway: towards metabolic equilibrium
http://hdl.handle.net/10468/3385
The kynurenine pathway: towards metabolic equilibrium
Clarke, Gerard; Stone, Trevor W.; Schwarcz, Robert
2017-01-01T00:00:00ZReturn of the King: time-series photometry of FO Aquarii’s initial recovery from its unprecedented 2016 low state
http://hdl.handle.net/10468/3482
Return of the King: time-series photometry of FO Aquarii’s initial recovery from its unprecedented 2016 low state
Littlefield, C.; Garnavich, P.; Kennedy, Mark R.; Aadland, E.; Terndrup, D. M.; Calhoun, G. V.; Callanan, Paul; Abe, L.; Bendjoya, P.; Rivet, J. P.; Vernet, D.; Devogéle, M.; Shappee, B.; Holoien, T.; Heras, T. A.; Bonnardeau, M.; Cook, M.; Coulter, D.; Debackére, A.; Dvorak, S.; Foster, J. R.; Goff, W.; Hambsch, F. J.; Harris, B.; Myers, G.; Nelson, P.; Popov, V.; Solomon, R.; Stein, W. L.; Stone, G.; Vietje, B.
In 2016 May, the intermediate polar FO Aqr was detected in a low state for the first time in its observational history. We report time-resolved photometry of the system during its initial recovery from this faint state. Our data, which includes high-speed photometry with cadences of just 2 s, show the existence of very strong periodicities at 22.5 and 11.26 minutes, equivalent to the spin–orbit beat frequency and twice its value, respectively. A pulse at the spin frequency is also present but at a much lower amplitude than is normally observed in the bright state. By comparing our power spectra with theoretical models, we infer that a substantial amount of accretion was stream-fed during our observations, in contrast to the disk-fed accretion that dominates the bright state. In addition, we find that FO Aqr's rate of recovery has been unusually slow in comparison to rates of recovery seen in other magnetic cataclysmic variables, with an e-folding time of 115 ± 7 days. The recovery also shows irregular variations in the median brightness of as much as 0.2 mag over a 10-day span. Finally, we show that the arrival times of the spin pulses are dependent upon the system's overall brightness.
2016-12-09T00:00:00ZBends in the plane with variable curvature
http://hdl.handle.net/10468/3502
Bends in the plane with variable curvature
Sheehan, Robert N.; Peters, Frank H.
Explicit formulae for planar variable curvature bends are constructed using Euler’s method of natural equations. The bend paths are expressed in terms of special functions. It is shown that the length of the different bend types varies linearly with increasing radius and that the curvature of variable curvature bends can be expressed as a multiple of the curvature of a circle.
2016-12-01T00:00:00ZCavity ring‑up spectroscopy for dissipative and dispersive sensing in a whispering gallery mode resonator
http://hdl.handle.net/10468/3384
Cavity ring‑up spectroscopy for dissipative and dispersive sensing in a whispering gallery mode resonator
Yang, Yong; Madugani, Ramgopal; Kasumie, Sho; Ward, Jonathan M.; Nic Chormaic, Síle
In whispering gallery mode resonator sensing applications, the conventional way to detect a change in the parameter to be measured is by observing the steady-state transmission spectrum through the coupling waveguide. Alternatively, sensing based on cavity ring-up spectroscopy, i.e. CRUS, can be achieved transiently. In this work, we investigate CRUS using coupled mode equations and find analytical solutions with a large spectral broadening approximation of the input pulse. The relationships between the frequency detuning, coupling gap and ring-up peak height are determined and experimentally verified using an ultrahigh Q-factor silica microsphere. This work shows that distinctive dispersive and dissipative transient sensing can be realised by simply measuring the peak height of the CRUS signal, which may improve the data collection rate.
2016-11-26T00:00:00Z