Effects of magnetic fields on radiatively overstable shock waves

We discuss high-resolution simulations of one-dimensional, plane-parallel shock waves with mean speeds between 150 and 240 km/s propagating into gas with Alfven velocities up to 40 km/s and outline the conditions under which these radiative shocks experience an oscillatory instability in the cooling length, shock velocity, and position of the shock front. We investigate two forms of postshock cooling: a truncated single power law and a more realistic piecewise power law. The degree of nonlinearity of the instability depends strongly on the cooling power law and the Alfven Mach number: for power-law indices \alpha < 0 typical magnetic field strengths may be insufficient either to stabilize the fundamental oscillatory mode or to prevent the oscillations from reaching nonlinear amplitudes.Comment: 11 text pages, LaTeX/AASTeX (aaspp4); 5 figures; accepted by Ap

Mangoes Made in Australia

Australian food products have a reputation for exceptional quality and are valued for by consumers for high safety standards. Recently, there have been several high profile incidents where Australian products “made from local and imported ingredients” have resulted in negative health outcomes which were traced back to produce that was not locally sourced. Local processing company Tropico Fruits produces an extensive range of fruit based products and list an Australian Kensington Pride mango puree among their flagship products. In light of the recent health issues arising from composite products using imported ingredients, the ability to test a processed product and identify the country of origin of it constituents is of great value to commercial enterprises that promote their products as locally sourced. Processed mango products are great candidates for assessing the feasibility of applying DNA-based identification methodologies for a number of reasons. DNA profiles have been determined for over 300 mango accession sourced from around the globe, including all the major domestic and overseas commercial varieties. Within all the commercial varieties, unique combinations of DNA markers exist such that a specific DNA profile can be traced back to the source variety. This means that even in composite purees, the major constituent varieties would be detected. To this end, four commercially produced mango purees were provided by Tropico Fruits and samples were subjected to a number of DNA extraction methodologies. While several of the methods produced workable quantities of highly degraded DNA, none of the extracted samples produced any results in the DNA fingerprinting steps. The objective of this project was to produce a set of reliable protocols that could determine the constituents of a processed product on the basis of a DNA profile. Unfortunately, while DNA was isolated using several techniques, the level of DNA degradation arising from the pureeing and sterilisation processes meant that DNA profiles could not be generate

Strategies for the treatment of Hepatitis C in an era of interferon-free therapies: what public health outcomes do we value most?

Objective: The expense of new therapies for HCV infection may force health systems to prioritise the treatment of certain patient groups over others. Our objective was to forecast the population impact of possible prioritisation strategies for the resource-rich setting of Scotland. Design: We created a dynamic Markov simulation model to reflect the HCV-infected population in Scotland. We determined trends in key outcomes (e.g. incident cases of chronic infection and severe liver morbidity (SLM)) until the year 2030, according to treatment strategies involving prioritising, either: (A) persons with moderate/advanced fibrosis or (B) persons who inject drugs (PWID). Results: Continuing to treat the same number of patients with the same characteristics will give rise to a fall in incident infection (from 600 cases in 2015 to 440 in 2030) and a fall in SLM (from 195 cases in 2015 to 145 in 2030). Doubling treatment-uptake and prioritising PWID will reduce incident infection to negligible levels (&#60;50 cases per year) by 2025, while SLM will stabilise (at 70–75 cases per year) in 2028. Alternatively, doubling the number of patients treated, but, instead, prioritising persons with moderate/advanced fibrosis will reduce incident infection less favourably (only to 280 cases in 2030), but SLM will stabilise by 2023 (i.e. earlier than any competing strategy). Conclusions: Prioritising treatment uptake among PWID will substantially impact incident transmission, however, this approach foregoes the optimal impact on SLM. Conversely, targeting those with moderate/advanced fibrosis has the greatest impact on SLM but is suboptimal in terms of averting incident infection

Towards a novel platform for imaging molecules in an optical lattice

This thesis reports on the development of a new apparatus which will be used to produce rovibrational ground state molecules with the goal of imaging them in an optical lattice. These types of experiments are often referred to as quantum gas microscopes. The two molecules which we wish to study are RbCs and KCs. RbCs has been already studied substantially at Durham but not in an apparatus as advanced as the one discussed in this thesis. RbCs and other ground state diatomic molecules may be formed in the rovibrational ground state by us- ing a magnetoassociation on an interspecies Feshbach resonance followed by stimulated Raman adiabatic passage (STIRAP). In our new apparatus we plan to repeat this in an optical lattice positioned directly above an object- ive with a high numerical aperture which will have the capability to resolve single lattice sites. Loading molecules into an optical lattice will allow access to dipolar physics associated with the intrinsic electric dipole moment of the molecule. This will grant us the capability to perform experiments, such as quantum simulation, that can yield a deeper understanding of the quantum nature of matter confined in lattices. In addition we show work towards KCs molecules, of which ground state molecules are yet to be formed. This molecule has a dipole moment of 1.92 D and a stable fermionic isotope which makes it a promising candidate for our studies in addition to RbCs. A new vacuum chamber apparatus is constructed. A pair of 2-dimensional magneto-optical traps (2D-MOTs), one for Cs and the other for K/Rb, provides a flux of atoms to the centre of our main vacuum chamber. Here the atoms are collected in a 3D-MOT. The 3D-MOT can accumulate 108 Cs atoms, 109 Rb atoms and 108 K atoms. The laser setups for our MOTs are also presented in this thesis. We laser cool Rb, Cs and K on their respective D2 transitions. There is a particular focus on the optimisation process of K. We have managed to cool a sample of 108 K atoms to 42(2) μK and obtain a simultaneous MOT of both K and Cs. We have potential plans to further cool K on the D1 line. To achieve this we need some means of high quality frequency stabilisation so a study on the modulation transfer spectroscopy of K and a comparison against the associated theory is also presented in this thesis. Using a moving optical standing wave the atoms are transported to the science cell. They will subsequently undergo various cooling stages until the phase space density is sufficiently high for magnetoassociation. This has been achieved with Rb and Cs but not yet for K and Cs. They will then be loaded into an optical lattice and associated into molecules. STIRAP requires lasers frequency stabilised to less than a kHz. The STIRAP setup is also described in detail in this thesis. We lock two lasers of wavelength 895 nm and 1359 nm to an ultra low expansion cavity and demonstrate proof of concept of how such a setup can serve the dual purpose of both STIRAP for KCs molecules and for exciting Cs atoms to Rydberg states using the Cs D1 transition

Crystal and Molecular Structures of Some Organometallic Compounds

In Part I of this thesis, I describe some aspects of crystal structure analysis; in particular those methods employed in this research. In Part II, the structural investigation of three organometallic complexes by X-ray diffraction is reported, viz. (N-ethoxycarbonyl-3-formylazepine)tricarbonyliron, pi-cyclopentadienyl-cis-dicarbonylbromo(triphenylphosphine)molybdenum -methylene chloride and pi-cyclopentadienyl-trans-dicarbonyliodo-(phenyl isocyanide)molybdenum. Previous X-ray analyses of azepine-tricarbonyliron complexes have shown that the geometry within the azepine ring is modified by substitution, therefore the structure elucidation of (N-ethoxycarbonyl-3-formylazepine)tricarbonyliron was undertaken in order to examine the geometry in a 1,3-substituted complex. Bond length variations consistent with those in the other complexes have been found. The structure determinations of the molybdenum complexes were undertaken to augment the already considerable structural comparisons possible among complexes of the type (pi-C5H5)MoL2XY. In the analysis of cis-(pi-C5H5)Mo(CO)2(PPh3)Br, halo/carbonyl disorder has prevented the determination of meaningful Mo-CO distances, but sensible values involving the other ligands have been obtained. The interest in the structure of trans-(n-C5H5)Mo(CO)2(CNPh)l was centred on the phenyl isocyanide ligand, for which an almost linear Mo-C-N-C geometry was found, with a Mo - CNPh bond length consistent with the pi-accepting ability of the phenyl isocyanide ligand being nearly comparable with that of the carbonyl ligands. In Part III, the characterization by X-ray analysis of a chromium and three iron organometallic complexes is reported. The analysis of the chromium complex was undertaken to determine whether the monomeric formulation, (pi-C5H5)Cr(NO)(NPh2)l, or a formulation involving weak iodine or nitrogen bridges was correct. The complex was found to be monomeric and structural comparisons have been made with related chromium-cyclopentadienyl-nitrosyl complexes. An X-ray analysis was carried out on the hexafluorophosphate salt of a stable intermediate isolated from the Friedel-Crafts acylation of (hexa-2,4-diene)tricarbonyliron, in order to assert whether the iron atom directs the entering electrophile endo or exo to the organic ligand. The configuration of the cation of the intermediate, tricarbonyl(2-4-n-hepten-5-methyl-6-one)iron, was found to be that resulting from endo-acylation. A product of the photochemical reaction of benzyldicarbonyl-(pi-cyclopentadienyl)iron with triphenylphosphine has been examined by X-ray diffraction and found to be (1-exo-benzylcyclopenta-2,4-diene)- dicarbonyl(triphenylphosphine)iron, in contradiction to the spectroscopic assignment. The tetracyanoethylene adduct of this product has been characterized by a further X-ray analysis as dicarbonyl (pi-cyclopentadienyl)(triphenylphosphine)iron 1,1,2,3,3-penta-cyanopropenide. As a consequence of disorder, accurate dimensions for the anion could not be obtained, but structural comparisons have been possible between the cation, formally a FeII complex, and its closely related precursor, formally a FeO complex. The most notable feature is a longer, ca. 0.03 A, Fe-P bond length in the FeII complex

Preformed metal crowns for decayed primary molar teeth

BackgroundPreformed metal crowns (PMCs) are recommended by the British Society of Paediatric Dentistry (BSPD) for restoring badly broken down primary molar teeth. However, few dental practitioners adopt this technique in clinical practice, citing cost and clinical difficulty as reasons for this. Whilst there is a subjective impression by clinical academics that PMCs provide a more durable restoration than filling materials, there appears to be little evidence within the literature to support this.ObjectivesThe primary aim of this systematic review was to compare clinical outcomes for primary molar teeth restored using PMCs compared to those restored with filling materials.Search methodsThe literature was searched using: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2005, Issue 3); MEDLINE (1966 to August 2005); EMBASE (1980 to August 2005); System for Information on Grey Literature in Europe (SIGLE) (1976 to August 2005). Relevant publications' reference lists were reviewed for relevant articles. The most recent search was carried out on 24 August 2005.Selection criteriaRandomised controlled trials (RCTs) that assessed the effectiveness of PMCs compared with filling materials or where there had been no treatment in children with untreated tooth decay in one or more primary molar teeth.Data collection and analysisTwo review authors independently assessed the title and abstracts for each article from the search results to decide whether it was likely to be relevant. Full papers were obtained for relevant articles and all three review authors studied these.Main resultsForty‐seven records were retrieved by the search strategies of which some were duplicates. Of these, 14 studies were scrutinised. No studies met the inclusion criteria and six studies were excluded from the review as they were either retrospective in design or reported as prospective outcomes but not randomised. No data were available for extraction and analysis and therefore, no conclusion could be made as to whether PMCs were more successful than filling materials for restoring primary molar teeth.Authors' conclusionsNo RCTs were available for appraisal. Whilst this technique is recommended by the BSPD for use in clinical practice, the evidence to support this is not strong, consisting mainly of case reports and uncontrolled studies. It is important that the absence of evidence for PMCs is not misinterpreted as evidence for their lack of efficacy.There is a strong need for prospective RCTs comparing PMCs and fillings for managing decayed primary molar teeth. The lower levels of evidence that have been produced, however, have strength in that the clinical outcomes are consistently in favour of PMCs, despite many of the studies placing PMCs on the most damaged of the pair of teeth being analysed

Dispersion of the solar magnetic flux in undisturbed photosphere as derived from SDO/HMI data

To explore the magnetic flux dispersion in the undisturbed solar photosphere, magnetograms acquired by Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamic Observatory (SDO) were utilized. Two areas, a coronal hole area (CH) and an area of super-granulation pattern, SG, were analyzed. We explored the displacement and separation spectra and the behavior of the turbulent diffusion coefficient, $K$. The displacement and separation spectra are very similar to each other. Small magnetic elements (of size 3-100 squared pixels and the detection threshold of 20 Mx sm$^{-2}$) in both CH and SG areas disperse in the same way and they are more mobile than the large elements (of size 20-400 squared pixels and the detection threshold of 130 Mx sm$^{-2}$). The regime of super-diffusivity is found for small elements ($\gamma \approx 1.3$ and $K$ growing from $\sim$100 to $\sim$ 300 km$^2$ s$^{-1}$). Large elements in the CH area are scanty and show super-diffusion with $\gamma \approx 1.2$ and $K$ = (62-96) km$^2$ s$^{-1}$ on rather narrow range of 500-2200 km. Large elements in the SG area demonstrate two ranges of linearity and two diffusivity regimes: sub-diffusivity on scales (900-2500) km with $\gamma=0.88$ and $K$ decreasing from $\sim$130 to $\sim$100 km$^2$ s$^{-1}$, and super-diffusivity on scales (2500-4800) km with $\gamma \approx 1.3$ and $K$ growing from $\sim$140 to $\sim$200 km$^2$ s$^{-1}$. Comparison of our results with the previously published shows that there is a tendency of saturation of the diffusion coefficient on large scales, i.e., the turbulent regime of super-diffusivity is gradually replaced by normal diffusion.Comment: 8 pages, 8 figure