Shop Notes

Contains reports on four research projects

Efficient Photoionization-Loading of Trapped Cadmium Ions with Ultrafast Pulses

Atomic cadmium ions are loaded into radiofrequency ion traps by photoionization of atoms in a cadmium vapor with ultrafast laser pulses. The photoionization is driven through an intermediate atomic resonance with a frequency-quadrupled mode-locked Ti:Sapphire laser that produces pulses of either 100 fsec or 1 psec duration at a central wavelength of 229 nm. The large bandwidth of the pulses photoionizes all velocity classes of the Cd vapor, resulting in high loading efficiencies compared to previous ion trap loading techniques. Measured loading rates are compared with a simple theoretical model, and we conclude that this technique can potentially ionize every atom traversing the laser beam within the trapping volume. This may allow the operation of ion traps with lower levels of background pressures and less trap electrode surface contamination. The technique and laser system reported here should be applicable to loading most laser-cooled ion species.Comment: 11 pages, 12 figure

Miscellaneous Problems

Contains reports on five research projects

The equilibria that allow bacterial persistence in human hosts

We propose that microbes that have developed persistent relationships with human hosts have evolved cross-signalling mechanisms that permit homeostasis that conforms to Nash equilibria and, more specifically, to evolutionarily stable strategies. This implies that a group of highly diverse organisms has evolved within the changing contexts of variation in effective human population size and lifespan, shaping the equilibria achieved, and creating relationships resembling climax communities. We propose that such ecosystems contain nested communities in which equilibrium at one level contributes to homeostasis at another. The model can aid prediction of equilibrium states in the context of further change: widespread immunodeficiency, changing population densities, or extinctions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62883/1/nature06198.pd

Advancing the understanding of treponemal disease in the past and present

Syphilis was perceived to be a new disease in Europe in the late 15th century, igniting a debate about its origin that continues today in anthropological, historical, and medical circles. We move beyond this age-old debate using an interdisciplinary approach that tackles broader questions to advance the understanding of treponemal infection (syphilis, yaws, bejel, and pinta). How did the causative organism(s) and humans co-evolve? How did the related diseases caused by Treponema pallidum emerge in different parts of the world and affect people across both time and space? How are T. pallidum subspecies related to the treponeme causing pinta? The current state of scholarship in specific areas is reviewed with recommendations made to stimulate future work. Understanding treponemal biology, genetic relationships, epidemiology, and clinical manifestations is crucial for vaccine development today and for investigating the distribution of infection in both modern and past populations. Paleopathologists must improve diagnostic criteria and use a standard approach for recording skeletal lesions on archaeological human remains. Adequate contextualization of cultural and environmental conditions is necessary, including site dating and justification for any corrections made for marine or freshwater reservoir effects. Biogeochemical analyses may assess aquatic contributions to diet, physiological changes arising from treponemal disease and its treatments (e.g., mercury), or residential mobility of those affected. Shifting the focus from point of origin to investigating who is affected (e.g., by age/sex or socioeconomic status) and disease distribution (e.g., coastal/ inland, rural/urban) will advance our understanding of the treponemal disease and its impact on people through time

Leisure, Popular Culture and Memory: The Invention of Dark Age Britain, Wales, England, and Middle-earth in the songs of Led Zeppelin

In the period of high modernity, and in the process of establishing the imperial nation-state of Great Britain, historians, archaeologists and enthusiastic amateurs searched high and low for material evidence and primary sources from what was called the Dark Ages. There is a gap in knowledge about this past, and all discussion rests on finding meaning in fading inscriptions, or dark earth, or trusting completely the writings of Bede and Gildas. The search for an identity and history for the nation for Great Britain was based on nationalist beliefs about Englishness, Britishness or Welshness. In the twentieth-century, the problem of Englishness, place and myth led Tolkien to write his Middle-earth stories in his leisure time. At the same time, the problem of Welshness or Britishness saw a growth in interest – in film and books - in Arthurian traditions, and a tourist interest in the Celtic fringe of Britain. In this paper, I show how the songs and album covers of Led Zeppelin, and their film The Song Remains the Same, draw upon both the work of Tolkien and the Arthurian traditions to construct ideas of masculine belonging in some mythological medieval time and place. While this constriction is idiosyncratic to the artists, they are drawing on and justifying the wider problem of England, Wales and Britain in leisure and culture