Microscopic measurement of photon echo formation in groups of individual excitonic transitions

The third-order polarization emitted from groups of individual localized excitonic transitions after pulsed optical excitation is measured. We observe the evolution of the nonlinear response from the case of a free polarization decay for a single transition, to that of a photon echo for many transitions. The echo is shown to arise from the mutual rephasing of the emission from individual transitions

Radical Possibilities: Literature In The English Revolution, 1640-1660

This dissertation explores the circulation of radical social and political ideas in the literature of the 1640-1660 Revolution, when England\u27s most fundamental institutions, from the monarchy to the patriarchal family, appeared in danger of annihilation. For students of literature, the period is so rich that its relative neglect seems remarkable. A lapse in government control over the nation\u27s printing presses resulted in a veritable explosion of books, pamphlets and broadsides, and a literature that offers an unprecedented diversity of views and voices. Surveying a wide range of texts, from the familiar to the lesser-known, my study draws upon insights gleaned from cultural-materialist, new-historicist, and feminist criticism in an attempt to view the culture of mid-seventeenth century England as a complex set of dialogues between elite and non-elite voices.;The first section deals with real and imagined threats to the hierarchy of social rank. It begins with a chapter on Brome\u27s A Jovial Crew, which, with its exploration of begging and vagrancy, anticipates the debates that would shortly achieve wide recognition with the rise of the Digger movement. The second chapter looks at constructions of popular political activism, with a focus on the role such constructions played in the propaganda war between the army leaders and those of the Leveller movement. The final chapter examines Marvell\u27s Upon Appleton House, which discloses the unsettling position of England\u27s wealthy landowners in the wake of the regicide.;Section II turns to the seemingly imperilled hierarchy of gender. It opens with a chapter on the writings of female petitioners and the satirical responses to their activities. An equally hostile response was accorded sectarian women who claimed the power of prophecy; the second chapter looks at their writings and their implications. The reactions to both groups demonstrate anxiety over the state of the family, the model and building block of the commonwealth. The final chapter highlights this connection between the family and the state through an examination of some contemporary uses of marriage as a political metaphor

Light shift averaging in paraffin-coated alkali vapor cells

Light shifts are an important source of noise and systematics in optically pumped magnetometers. We demonstrate that the long spin coherence time in paraffin-coated cells leads to spatial averaging of the light shifts over the entire cell volume. This renders the averaged light shift independent, under certain approximations, of the light-intensity distribution within the sensor cell. These results and the underlying mechanism can be extended to other spatially varying phenomena in anti-relaxation-coated cells with long coherence times.Comment: 6 pages, 4 figure

An open-source alignment method for multichannel infinite-conjugate microscopes using a ray transfer matrix analysis model

Multichannel, infinite-conjugate optical systems easily allow implementation of multiple image paths and imaging modes into a single microscope. Traditional optical alignment methods which rely on additional hardware are not always simple to implement, particularly in compact open-source microscope designs. We present here an alignment algorithm and process to position the lenses and cameras in a microscope using only image magnification measurements. We show that the resulting positioning accuracy is comparable to the axial resolution of the microscope. Ray transfer matrix analysis is used to model the imaging paths when the optics are both correctly and incorrectly aligned. This is used to derive the corresponding image magnifications. We can then extract information about the lens positions using simple image-based measurements to determine whether there is misalignment of the objective lens to sample distance (working distance) and with what magnitude and direction the objective lens needs to be adjusted. Using the M4All open-source 3D printable microscope system in combination with the OpenFlexure microscope, we validate the alignment method and highlight its usability. We provide the model and an example implementation of the algorithm as an open-source Jupyter Notebook

Search for plant biomagnetism with a sensitive atomic magnetometer

We report what we believe is the first experimental limit placed on plant biomagnetism. Measurements with a sensitive atomic magnetometer were performed on the Titan arum (Amorphophallus titanum) inflorescence, known for its fast bio-chemical processes while blooming. We find that the surface magnetic field from these processes, projected along the Earth's magnetic field, and measured at the surface of the plant, is less then ~0.6uG.Comment: 5 pages, 5 figures, to be published - modified one sentence in abstract + reformatted fi