Calibration of the prototype Planetary Instrument for X-ray Lithochemistry (PIXL) selected for Mars 2020 has commenced with an empirical derivation of the X-ray optic transmission profile. Through a straightforward method of dividing a measured “blank” spectrum over one calculated assuming no optic influence, a rudimentary profile was formed. A simple boxcar-smoothing algorithm was implemented to approximate the complete profile that was incorporated into PIQUANT. Use of this form of smoothing differs from the more conventional approach of using a parameter-based function to complete the profile. Comparison of element-specific correction factors, taken from a measurement of NIST SRM 610, was used to assess the accuracy of the new profile. Improvement in the low- to mid-energy portion of the data was apparent though the high-energy region diverged from unity, and thus, requires further refinement.

We investigated norovirus (NoV) concentrations and genotypes in oyster and faecal samples associated with two separate oyster-related outbreaks of gastroenteritis in Ireland. Quantitative analysis was performed using real-time quantitative reverse transcription polymerase chain reaction and phylogenetic analysis was conducted to establish the NoV genotypes present. For both outbreaks, the NoV concentration in oysters was >1000 genome copies/g digestive tissue and multiple genotypes were identified. In faecal samples, GII.13 was the only genotype detected for outbreak 1, whereas multiple genotypes were detected in outbreak 2 following the application of cloning procedures. While various genotypes were identified in oyster samples, not all were successful in causing infection in consumers. In outbreak 2 NoV GII.1 was identified in all four faecal samples analysed and NoV GII concentrations in faecal samples were >108 copies/g. This study demonstrates that a range of NoV genotypes can be present in highly contaminated oysters responsible for gastroenteritis outbreaks.

The advancement of imprint lithography as a method for fabricating nanostructures is impeded by a lack of effective tools for characterizing mechanical properties and geometry at the nanoscale. In this report, we describe the development of methods for determining elastic moduli and cross sectional dimensions of imprinted nanolines from Brillouin light scattering (BLS) measurements using finite-element (FE) and Farnell-Adler models for the vibrational modes. An array of parallel nanoimprinted lines of polymethyl methacrylate (PMMA) with widths of ∼65 nm and heights of ∼140 nm served as a model specimen. Several acoustic modes were observed with BLS in the low-gigahertz frequency range, and the forms of the vibrational displacements were identified through correlation with calculations using measured bulk-PMMA moduli and density as input. The acoustic modes include several flexural, Rayleigh-like, and Sezawa-like modes. Fitting of Farnell-Adler calculations to the measured dispersion curves was explored as a means of extracting elastic moduli and nanoline dimensions from the data. Some values obtained from this inversion analysis were unrealistic, which suggests that geometric approximations in the model introduce significant systematic errors. In forward calculations, the frequencies determined with the FE method are found to more closely match measured frequencies. This suggests that the FE approach may be more accurate for inversion analysis. Initial estimates of uncertainties in the FE calculations support this conclusion.

The postcricoid subsite is difficult to visualize on flexible laryngopharyngoscopy. The view can be improved with either auto-insufflation manoeuvres or anterior neck skin traction. In this study, the view of the hypopharynx was graded whilst anterior neck skin traction was applied during the trumpet manoeuvre; the latter involves the patient blowing on his finger as if blowing up a balloon. On auto-insufflation alone, the postcricoid site was demonstrated in 22/25 (88 per cent) of cases and the upper oesophageal sphincter (UOS) in two out of 25 (eight per cent). Of the 22 cases in whom only the postcricoid site was demonstrated, subsequent neck skin traction revealed the UOS in eight. Overall, the use of auto-insufflationsolely or in combination with traction resulted in UOS visualization in 40 per cent (10/25) of cases. The application of skin traction during trumpeting is easy to perform and should be used routinely.

This paper discusses the growth of Mg-doped GaN samples using a modified Molecular Beam Epitaxy (MBE) method. Our results suggest that the dopant is incorporated from a surface population maintained by the incident Mg flux by a rapid diffusion mechanism. It follows that the chemical concentration will increase with time of growth and that the p-doping level will also increase progressively with film thickness for a given Mg flux. Increasing the Mg flux to the surface results at first in a higher doping density, but this saturates when the Mg surface concentration reaches a finite value.

We report two cases of recurrent layngeal papillomatosis in women who subsequently developed squamous cell carcinoma as they approached the climateric. The role of human papilloma virus (HPV) and oestrogen metabolism is outlined. The use of indoles from cruciferous vegetables is also discussed.

Concern has been expressed regarding the seeding of viral DNA, in laryngeal papillomatosis, to other sites in the respiratory tract during treatment. Controversy exists regarding the concept of seeding by the laser plume. However, instrumentation and anaesthetic intubation are also strongly implicated in seeding DNA to the proximal respiratory tract. No cases of recurrent laryngeal papillomatosis and subsequent papilloma in the paranasal sinuses have been reported.

We have developed several x-ray microtomography systems which function as quantitative three dimensional x-ray microscopes. In this paper we describe the evolutionary path followed from making the first high resolution experimental microscopes to later generations which can be routinely used for investigating materials. Developing the instrumentation for reliable quantitative x-ray microscopy using synchrotron and laboratory based x-ray sources has led to other imaging modalities for obtaining temporal and spatial two dimensional information.

The design of an x-ray detector suitable for use in tomography must be optimized for the intended application. Recently, we have developed microtomography applications that require resolution of -1 micron in three spatial dimensions and -1% statistical accuracy in the reconstruction of attenuation coefficients for each cubic micron volume element in a .1 cubic mm specimen. X-ray detector design for these applications must take into account much more than just the demanding micron spatial resolution requirement. The detector must be optimized to take into account the physical properties of the specimen to be measured, the characteristics of the x-ray beam available to probe the specimen, signal to noise ratios needed in the reconstructed image and requirements of the data processing algorithm. In addition, the detector design should be sufficiently flexible to allow significant variation in the kinds of specimens that can be examined.