In the Absence of Peace

Today, the Monday after the attack, all of the flags were at half mast. Everything continued as normal, as if nothing had happened. Yet there was an intensity in the air. I didn’t notice the increased police, but it was easy to feel the increased security. [excerpt

On White Guilt.

I didn’t always realize what white guilt was, only that it existed. It’s not as cut-and-dry as it seems. It actually took me years to understand it, which is why I was not surprised when at the Town Hall Meeting back in January, one person asked a question about how to be an ally. Specifically, I found myself reflecting on her concerns regarding “white guilt” (44:01 – 45:25). I wanted to respond, but from the audience it felt out of place, and as it is, my response took two months of putting my thoughts together. [excerpt

Ultrafast measurements in condensed matter

In this thesis I describe the development of an apparatus for performing attosecond photoelectron measurements in condensed matter, and the completion of attosecond streaking measurements on metal films using the apparatus. A commercial Ti:sapphire chirped pulse amplification laser system was used to generate 28fs, 2.5mJ pulses with a central wavelength of 790nm and a 1kHz repetition rate. These pulses were post-compressed using a hollow fibre system. The resulting few-cycle pulses had sub-4fs duration, and 0.4mJ energy. Diagnostics performed on the hollow fibre system revealed ionisation induced carrier-envelope phase fluctuations at input pulse energies in excess of 1mJ. These fluctuations were avoided for attosecond experiments by careful choice of the experimental parameters. The few-cycle pulses were used to generate isolated attosecond pulses through high-harmonic generation, in an amplitude-gating scheme. An ultra-high vacuum compatible two-part extreme-ultraviolet multilayer mirror setup was developed for attosecond streaking measurements on surfaces. The base pressure in the experimental chamber is 3 × 10^−9 mbar. Attosecond streaking measurements were performed on amorphous WO3 and polycrystalline Au, without any prior surface cleaning. The results indicate the applicability of attosecond streaking to a very general class of solid state samples. In WO3 the 4f photoemission precedes the valence photoemission by 140 ± 190as. In gold, possible signatures of plasmon dynamics were detected.Open Acces

The Other N Word

As we waited for a ride, I noticed my friend’s shirt. It looked strange and disjointed. It was white and black and looked like cut up picture of a contorted woman. Taken aback, I asked what it was. “I don’t know,” he replied. “I like it because it looks Nazi.” [excerpt

NK cells as effectors of acquired immune responses: effector CD4+ T cell-dependent activation of NK cells following vaccination.

We characterized vaccine-induced cellular responses to rabies virus in naive adult volunteers. Contrary to current paradigms, we observed potent and prolonged in vitro NK cell cytokine production and degranulation responses after restimulation of PBMCs with inactivated rabies virus in vaccinated, but not in unvaccinated, individuals. This "recall" NK cell response was absolutely dependent on Ag-specific IL-2 from CD45RO(+) CD4(+) T cells as well as IL-12 and IL-18 from accessory cells. Importantly, NK cells represented over 70% of all IFN-gamma-secreting and degranulating cells in the first 12-18 h after virus rechallenge indicating they may be required for rapid control of infection after vaccination. Activation of NK cells may be a critical function of IL-2-secreting effector memory T cells. Although IL-2-dependent postvaccination NK cell activation has been reported previously, this is the first time the magnitude of this effect and its contribution to the overall vaccine-induced response has been appreciated and the mechanisms of NK activation postvaccination have been elucidated. Our data will allow standard protocols for evaluating vaccine-induced immunity to be adapted to assess NK cell effector responses