Maxwell Duality, Lorentz Invariance, and Topological Phase

We discuss the Maxwell electromagnetic duality relations between the Aharonov-Bohm, Aharonov-Casher, and He-McKellar-Wilkens topological phases, which allows a unified description of all three phenomena. We also elucidate Lorentz transformations that allow these effects to be understood in an intuitive fashion in the rest frame of the moving quantum particle. Finally, we propose two experimental schemes for measuring the He-McKellar-Wilkens phase.Comment: 10 pages, 2 figure

Micro-combs: a novel generation of optical sources

The quest towards the integration of ultra-fast, high-precision optical clocks is reflected in the large number of high-impact papers on the topic published in the last few years. This interest has been catalysed by the impact that high-precision optical frequency combs (OFCs) have had on metrology and spectroscopy in the last decade [1–5]. OFCs are often referred to as optical rulers: their spectra consist of a precise sequence of discrete and equally-spaced spectral lines that represent precise marks in frequency. Their importance was recognised worldwide with the 2005 Nobel Prize being awarded to T.W. Hänsch and J. Hall for their breakthrough in OFC science [5]. They demonstrated that a coherent OFC source with a large spectrum – covering at least one octave – can be stabilised with a self-referenced approach, where the frequency and the phase do not vary and are completely determined by the source physical parameters. These fully stabilised OFCs solved the challenge of directly measuring optical frequencies and are now exploited as the most accurate time references available, ready to replace the current standard for time. Very recent advancements in the fabrication technology of optical micro-cavities [6] are contributing to the development of OFC sources. These efforts may open up the way to realise ultra-fast and stable optical clocks and pulsed sources with extremely high repetition-rates, in the form of compact and integrated devices. Indeed, the fabrication of high-quality factor (high-Q) micro-resonators, capable of dramatically amplifying the optical field, can be considered a photonics breakthrough that has boosted not only the scientific investigation of OFC sources [7–13] but also of optical sensors and compact light modulators [6,14]

Increased generation of superoxide by angiotensin II in smooth muscle cells from resistance arteries of hypertensive patients: role of phospholipase D-dependent NAD(P)H oxidase-sensitive pathways

<b>Objective:</b> We tested the hypothesis that increased responsiveness of phospholipase D (PLD) to angiotensin II (Ang II) is associated with increased oxidative stress and exaggerated growth responses in vascular smooth muscle cells (VSMC) from untreated essential hypertensive patients.<p></p> <b>Design:</b> VSMCs from peripheral resistance arteries of normotensive and hypertensive subjects were studied. Production of reactive oxygen species (ROS) was measured with the fluoroprobe 5-(and 6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (CM-H2DCFDA). PLD and reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) oxidase were assessed with the inhibitors, dihydro-d-erythro-sphingosine (sphinganine) and diphenylene iodinium (DPI), respectively, and protein kinase C (PKC) effects were determined using chelerythrine chloride and calphostin C. PLD activity was measured by the transphosphatidylation assay.<p></p> <b>Results:</b> Ang II increased the CM-H2DCFDA fluorescence signal, derived predominantly from H2O2. Ang II-induced generation of DPI-inhibitable ROS was significantly enhanced in cells from hypertensives compared with normotensives (Emax = 7