Limitations of Dental Panoramic Tomography in the anterior mandible

Dental Panoramic Tomography (DPT) is a widely used and valuable examination in dentistry. One area prone to artefacts and therefore misinterpretation is the anterior region of the mandible. This case study discusses a periapical radiolucency related to lower anterior teeth that is discovered to be a radiographic artefact. Possible causes of the artefact include a pronounced depression in the mental region of the mandible or superimposition of intervertebral spaces. Additional limitations of the DPT image include superimposition of radio-opaque structures, reduced image detail compared to intra-oral views and uneven magnification. These problems often make the DPT inappropriate for imaging the anterior mandible.

CLINICAL RELEVANCE: Panoramic radiography is often unsuitable for radiographic examination of the anterior mandible.

Proton Radiography of a Laser-Driven Implosion

Protons accelerated by a picosecond laser pulse have been used to radiograph a 500 mu m diameter capsule, imploded with 300 J of laser light in 6 symmetrically incident beams of wavelength 1.054 mu m and pulse length 1 ns. Point projection proton backlighting was used to characterize the density gradients at discrete times through the implosion. Asymmetries were diagnosed both during the early and stagnation stages of the implosion. Comparison with analytic scattering theory and simple Monte Carlo simulations were consistent with a 3 +/- 1 g/cm(3) core with diameter 85 +/- 10 mu m. Scaling simulations show that protons > 50 MeV are required to diagnose asymmetry in ignition scale conditions.

National Identity and National Unity in Contemporary East Timorese Literature

Beginning with a panoramic analysis of the role played by East Timorese poets in the struggle for liberation from Portuguese and Indonesian colonial rule, this article examines the extent to which an East Timorese national identity and unity repeatedly featured in the poetry of the 1970s and 80s are represented in contemporary Timorese literary production. By reading the work of the novelist Luís Cardoso, and the poets Abé Barreto and Celso Oliveira, the article also assesses whether the independent nation envisioned earlier by those such as Borja da Costa, Fernando Sylvan and Xanana Gusmão, has been realised. In doing so, critical attention is brought to bear on the intimate relationship between the specific material and political circumstances of East Timor and the literature produced in colonial and postcolonial moments in the nation’s history.

A method to reconstruct patient-specific proximal femur surface models from planar pre-operative radiographs

Three-dimensional reconstruction from volumetric medical images (e.g. CT, MRI) is a well-established technology used in patient-specific modelling. However, there are many cases where only 2D (planar) images may be available, e.g. if radiation dose must be limited or if retrospective data is being used from periods when 3D data was not available. This study aims to address such cases by proposing an automated method to create 3D surface models from planar radiographs. The method consists of (i) contour extraction from the radiograph using an Active Contour (Snake) algorithm, (ii) selection of a closest matching 3D model from a library of generic models, and (iii) warping the selected generic model to improve correlation with the extracted contour.

This method proved to be fully automated, rapid and robust on a given set of radiographs. Measured mean surface distance error values were low when comparing models reconstructed from matching pairs of CT scans and planar X-rays (2.57–3.74 mm) and within ranges of similar studies. Benefits of the method are that it requires a single radiographic image to perform the surface reconstruction task and it is fully automated. Mechanical simulations of loaded bone with different levels of reconstruction accuracy showed that an error in predicted strain fields grows proportionally to the error level in geometric precision. In conclusion, models generated by the proposed technique are deemed acceptable to perform realistic patient-specific simulations when 3D data sources are unavailable.

Bright Laser-Driven Neutron Source Based on the Relativistic Transparency of Solids

Neutrons are unique particles to probe samples in many ?elds of research ranging from biology to material sciences to engineering and security applications. Access to bright, pulsed sources is currently
limited to large accelerator facilities and there has been a growing need for compact sources over the recent years. Short pulse laser driven neutron sources could be a compact and relatively cheap way to
produce neutrons with energies in excess of 10 MeV. For more than a decade experiments have tried to obtain neutron numbers suf?cient for applications. Our recent experiments demonstrated an ion acceleration mechanism based on the concept of relativistic transparency. Using this new mechanism, we produced an intense beam of high energy (up to 170 MeV) deuterons directed into a Be converter to
produce a forward peaked neutron ?ux with a record yield, on the order of 1010 n=sr. We present results comparing the two acceleration mechanisms and the ?rst short pulse laser generated neutron radiograph.

Before the “Comics:” On the Seriality of Graphic Narratives during the Nineteenth Century

While the connection between seriality and comics in the twentieth century has frequently been a subject of study, far less attention has been paid to the role of serialisation in the previous century, when the language of comics gradually developed in the illustrated and satirical press. This article discusses a heterogeneous group of graphic narratives published in various European countries between the 1830s and the 1880s, before a new generation of comic magazines influenced by American newspaper strips transformed this emerging field into the autonomous medium of comics. Serial works flourished during this period and included diverse modes, such as series of “graphic novels,” the use of recurring characters, the serialisation of picture stories in humour periodicals, and the use of graphic narratives as a regular feature in the illustrated news magazines. By providing a panoramic survey of various types of serial texts, the article suggests that the hybrid nature of these graphic narratives and the publishing strategies applied to them can be better understood if considered in relation to the larger context of nineteenth-century print culture, rather than in comparison with the future of the medium.