41,285 research outputs found
Lag of Low-Energy Photons in an X-ray Burst Oscillation: Doppler Delays
Numerous X-ray bursts show strong oscillations in their flux at several
hundred Hz as revealed by RXTE. Analyzing one such oscillation from the X-ray
binary Aql X-1, I find that low energy photons (3.5-5.7 keV) lag high energy
photons (>5.7 keV) by approximately 1 radian. The oscillations are thought to
be produced by hot spots on the spinning neutron star. The lags can then be
explained by a Doppler shifting of emission from the hot spots; higher energy
photons being emitted earlier in the spin phase as the spot approaches the
observer. A quantitative test of this simple model shows a remarkable agreement
with the data. Similar low energy lags have been measured in kilohertz
quasi-periodic oscillations and in the accreting millisecond pulsar SAX
J1808.4-3658. A Doppler delay mechanism may be at work there as well.Comment: accepted ApJ Letter
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Photochemical delivery of nitric oxide.
There remains considerable interest in developing methods for the targeted delivery of nitric oxide and other small molecule bioregulators such as carbon monoxide to physiological targets. One such strategy is to use a "caged" NO that is "uncaged" by excitation with light. Such photochemical methods convey certain key advantages such as the ability to control the timing, location and dosage of delivery, but also have some important disadvantages, such as the relatively poor penetration of the ultraviolet and visible wavelengths often necessary for the uncaging process. Presented here is an overview of ongoing studies in the author's laboratory exploring new photochemical NO precursors including those with nanomaterial antennas designed to enhance the effectiveness of these precursors with longer excitation wavelengths
On the Canonical Equivalence of Liouville and Free Fields
We obtain the parity invariant generating functional for the canonical
transformation mapping the Liouville theory into a free scalar field and
explain how it is related to the pseudoscalar transformationComment: 8 pages, Latex, Important earlier work by G.P. Jordadze acknowledge
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The pricing journey – The evolution of approach and execution as organisational pricing capability develops
This is an author version of an article which has been published in its definitive form as a Margin2 / Brunel Pricing Forum white paper and has been posted by permission of the Brunel Pricing Forum for personal use, not for redistribution. The article was published online by Margin2 and the original version can be accessed at the link below.An organisation’s approach to Pricing can be seen as a competency in the sense that it is a combination of skills, behaviours and the application of knowledge. As the efficiency and effectiveness of pricing decisions improve, then a range of indicators highlight a more thorough, considered and generally more successful approach. Fewer mistakes are made, results are more visibility linked to previous actions, and implementation becomes quicker and more comprehensive
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