Radiotherapy in the presence of contrast agents: a general figure of merit and its application to gold nanoparticles

Delivering sufficient dose to tumours while sparing surrounding tissue is one of the primary challenges of radiotherapy, and in common practice this is typically achieved by using highly penetrating MV photon beams and spatially shaping dose. However, there has been a recent increase in interest in the possibility of using contrast agents with high atomic number to enhance the dose deposited in tumours when used in conjunction with kV x-rays, which see a significant increase in absorption due to the heavy element's high-photoelectric cross-section at such energies. Unfortunately, the introduction of such contrast agents significantly complicates the comparison of different source types for treatment efficacy, as the dose deposited now depends very strongly on the exact composition of the spectrum, making traditional metrics such as beam quality less valuable. To address this, a 'figure of merit' is proposed, which yields a value which enables the direct comparison of different source types for tumours at different depths inside a patient. This figure of merit is evaluated for a 15 MV LINAC source and two 150 kVp sources (both of which make use of a tungsten target, one with conventional aluminium filtration, while the other uses a more aggressive thorium filter) through analytical methods as well as numerical models, considering tissue treated with a realistic concentration and uptake ratio of gold nanoparticle contrast agents (10 mg ml(-1) concentration in 'tumour' volume, 10: 1 uptake ratio). Finally, a test case of human neck phantom is considered with a similar contrast agent to compare the abstract figure to a more realistic treatment situation. Good agreement was found both between the different approaches to calculate the figure of merit, and between the figure of merit and the effectiveness in a more realistic patient scenario. Together, these observations suggest that there is the potential for contrast-enhanced kilovoltage radiation to be a useful therapeutic tool for a number of classes of tumour on dosimetric considerations alone, and they point to the need for further research in this area.

Bluestocking Feminism Revisited: The Satirical Figure of the Bluestocking

Recent debates about the Bluestockings have focused on the lives, writings and political opinions of the Bluestockings themselves. This article argues that the significance of the Bluestockings, however, lies in the ways in which they were figured in public representations. It examines the tradition of satires of the Bluestockings, showing how this tradition both continued earlier traditions of satire against the learned lady and invented the comic figure of the literary hostess. The satires’ crude attacks on intellectual women ultimately raised the profile of the learned lady, a figure whose incipient feminism bore no necessary relation to the historical Bluestockings themselves.

Human figure segmentation using independent component analysis

In this paper, we present a Statistical Shape Model for Human Figure Segmentation in gait sequences. Point Distribution Models (PDM) generally use Principal Component analysis (PCA) to describe the main directions of variation in the training set. However, PCA assumes a number of restrictions on the data that do not always hold. In this work, we explore the potential of Independent Component Analysis (ICA) as an alternative shape decomposition to the PDM-based Human Figure Segmentation. The shape model obtained enables accurate estimation of human figures despite segmentation errors in the input silhouettes and has really good convergence qualities.

Sex, Politics and Religion: The Transformation of the Figure of the Fairy Queen from Thomas off Ersseldoune to ‘‘Thomas Rymer’’

Our earliest version of the Thomas Rymer story is the medieval romance Thomas off Ersseldoune (c.1430). There is a four hundred year lacuna before the ballad “Thomas Rymer”, our next surviving version, is recorded in the early 1800s. In the intervening time the narrative changed very little but the dynamic of the piece, radically. The romance transformed into the highly subversive ballad, “Thomas Rymer”. Central to this transformation is the reconceptualization of the romance's heroine. Referred to simply as the “lufly lady” and caught between her husband, the fay King, and a mere mortal, Thomas, she becomes in the ballad the powerful Queen of the Fairies. The ballad is structured around a series of revelations in which the enigmatic Queen assumes the roles of Eve and Mary, and finally Christ Himself. I will explore the implications of this extraordinary ballad. Moreover, I suggest that it is Queen Elizabeth herself who, ironically, enables the heroine's transformation. “Ironically” because it appears that it was Elizabeth's own restrictions, designed to suppress heretical, seditious or radical literature, which forced Thomas off Ersseldoune (and many other romances which employed religious imagery or figures) out of the written domain and into the oral tradition. And yet, it is Elizabeth who, in creating the image of herself as a female prince, as the Faerie Queen, inspires a new literary vocabulary designed to describe female executive power, without which it would have been impossible to imagine a figure such as the ballad's Queen of the Fairies.