High resolution structural characterisation of laser-induced defect clusters inside diamond

Laser writing with ultrashort pulses provides a potential route for the manufacture of three-dimensional wires, waveguides and defects within diamond. We present a transmission electron microscopy (TEM) study of the intrinsic structure of the laser modifications and reveal a complex distribution of defects. Electron energy loss spectroscopy (EELS) indicates that the majority of the irradiated region remains as $sp^3$ bonded diamond. Electrically-conductive paths are attributed to the formation of multiple nano-scale, $sp^2$-bonded graphitic wires and a network of strain-relieving micro-cracks

Reviews

The following publications have been reviewed by the mentioned authors;Design Assignments for GCSE and Standard Grade by Jeff Nocholls, reviewed by Bob BoothDesign and Communication for Foundation Courses by Peter Gowers, reviewed by Peter ToftThe Celtic Art Source Book by Courtney Davis, reviewed by Rosemary BoothThe World of Plastics by the British Plastics Federation, reviewed by George RaperIllumination: A Source Book for Modern Calligraphers by Christopher Jarman, reviewed by John LancasterCraft, Design and Technology. Materials: Investigation and Choice. A database for pupil use by David Barles, Simon Powell, Sheila Nelmes and Adrienne Jones, reviewed by David BarlexDesign in Context by Penny Sparke, reviewed by John H. CarswellDesignwise 2 by N. McLean, reviewed by H. G. DentonAirbrushing the Human Form by Andy Charlesworth, reviewed by S. W. GarnerDouglas Scott by Johnathan Glancey, reviewed by K. J. McAule

Variational approximation for mixtures of linear mixed models

Mixtures of linear mixed models (MLMMs) are useful for clustering grouped data and can be estimated by likelihood maximization through the EM algorithm. The conventional approach to determining a suitable number of components is to compare different mixture models using penalized log-likelihood criteria such as BIC.We propose fitting MLMMs with variational methods which can perform parameter estimation and model selection simultaneously. A variational approximation is described where the variational lower bound and parameter updates are in closed form, allowing fast evaluation. A new variational greedy algorithm is developed for model selection and learning of the mixture components. This approach allows an automatic initialization of the algorithm and returns a plausible number of mixture components automatically. In cases of weak identifiability of certain model parameters, we use hierarchical centering to reparametrize the model and show empirically that there is a gain in efficiency by variational algorithms similar to that in MCMC algorithms. Related to this, we prove that the approximate rate of convergence of variational algorithms by Gaussian approximation is equal to that of the corresponding Gibbs sampler which suggests that reparametrizations can lead to improved convergence in variational algorithms as well.Comment: 36 pages, 5 figures, 2 tables, submitted to JCG

Resolved Debris Discs Around A Stars in the Herschel DEBRIS Survey

The majority of debris discs discovered so far have only been detected through infrared excess emission above stellar photospheres. While disc properties can be inferred from unresolved photometry alone under various assumptions for the physical properties of dust grains, there is a degeneracy between disc radius and dust temperature that depends on the grain size distribution and optical properties. By resolving the disc we can measure the actual location of the dust. The launch of Herschel, with an angular resolution superior to previous far-infrared telescopes, allows us to spatially resolve more discs and locate the dust directly. Here we present the nine resolved discs around A stars between 20 and 40 pc observed by the DEBRIS survey. We use these data to investigate the disc radii by fitting narrow ring models to images at 70, 100 and 160 {\mu}m and by fitting blackbodies to full spectral energy distributions. We do this with the aim of finding an improved way of estimating disc radii for unresolved systems. The ratio between the resolved and blackbody radii varies between 1 and 2.5. This ratio is inversely correlated with luminosity and any remaining discrepancies are most likely explained by differences to the minimum size of grain in the size distribution or differences in composition. We find that three of the systems are well fit by a narrow ring, two systems are borderline cases and the other four likely require wider or multiple rings to fully explain the observations, reflecting the diversity of planetary systems.Comment: 19 pages, 13 figures, 6 tables. Accepted for publication in MNRA

Index Patient and SARS Outbreak in Hong Kong

During the global outbreak of severe acute respiratory syndrome (SARS) in 2003, treatment was empiric. We report the case history of the index patient in a hospital outbreak of SARS in Hong Kong. The patient recovered after conventional antimicrobial therapy. Further studies are needed to address treatment of SARS, which has high attack and death rates

ALMA 1.3 Millimeter Map of the HD 95086 System

Planets and minor bodies such as asteroids, Kuiper-belt objects and comets are integral components of a planetary system. Interactions among them leave clues about the formation process of a planetary system. The signature of such interactions is most prominent through observations of its debris disk at millimeter wavelengths where emission is dominated by the population of large grains that stay close to their parent bodies. Here we present ALMA 1.3 mm observations of HD 95086, a young early-type star that hosts a directly imaged giant planet b and a massive debris disk with both asteroid- and Kuiper-belt analogs. The location of the Kuiper-belt analog is resolved for the first time. The system can be depicted as a broad ($\Delta R/R \sim$0.84), inclined (30\arcdeg$\pm$3\arcdeg) ring with millimeter emission peaked at 200$\pm$6 au from the star. The 1.3 mm disk emission is consistent with a broad disk with sharp boundaries from 106$\pm$6 to 320$\pm$20 au with a surface density distribution described by a power law with an index of --0.5$\pm$0.2. Our deep ALMA map also reveals a bright source located near the edge of the ring, whose brightness at 1.3 mm and potential spectral energy distribution are consistent with it being a luminous star-forming galaxy at high redshift. We set constraints on the orbital properties of planet b assuming co-planarity with the observed disk.Comment: accepted for publication in A

The debris disk around gamma Doradus resolved with Herschel

We present observations of the debris disk around gamma Doradus, an F1V star, from the Herschel Key Programme DEBRIS (Disc Emission via Bias-free Reconnaissance in the Infrared/Submillimetre). The disk is well-resolved at 70, 100 and 160 micron, resolved along its major axis at 250 micron, detected but not resolved at 350 micron, and confused with a background source at 500 micron. It is one of our best resolved targets and we find it to have a radially broad dust distribution. The modelling of the resolved images cannot distinguish between two configurations: an arrangement of a warm inner ring at several AU (best-fit 4 AU) and a cool outer belt extending from ~55 to 400 AU or an arrangement of two cool, narrow rings at ~70 AU and ~190 AU. This suggests that any configuration between these two is also possible. Both models have a total fractional luminosity of ~10^{-5} and are consistent with the disk being aligned with the stellar equator. The inner edge of either possible configuration suggests that the most likely region to find planets in this system would be within ~55 AU of the star. A transient event is not needed to explain the warm dust's fractional luminosity.Comment: 12 pages, 6 figures, accepted for publication in Ap

Associations between dietary iron and zinc intakes, and between biochemical iron and zinc status in women

Iron and zinc are found in similar foods and absorption of both may be affected by food compounds, thus biochemical iron and zinc status may be related. This cross-sectional study aimed to: (1) describe dietary intakes and biochemical status of iron and zinc; (2) investigate associations between dietary iron and zinc intakes; and (3) investigate associations between biochemical iron and zinc status in a sample of premenopausal women aged 18–50 years who were recruited in Melbourne and Sydney, Australia. Usual dietary intakes were assessed using a 154-item food frequency questionnaire (n = 379). Iron status was assessed using serum ferritin and hemoglobin, zinc status using serum zinc (standardized to 08:00 collection), and presence of infection/inflammation using C-reactive protein (n = 326). Associations were explored using multiple regression and logistic regression. Mean (SD) iron and zinc intakes were 10.5 (3.5) mg/day and 9.3 (3.8) mg/day, respectively. Median (interquartile range) serum ferritin was 22 (12–38) μg/L and mean serum zinc concentrations (SD) were 12.6 (1.7) μmol/L in fasting samples and 11.8 (2.0) μmol/L in nonfasting samples. For each 1 mg/day increase in dietary iron intake, zinc intake increased by 0.4 mg/day. Each 1 μmol/L increase in serum zinc corresponded to a 6% increase in serum ferritin, however women with low serum zinc concentration (AM fasting < 10.7 μmol/L; AM nonfasting < 10.1 μmol/L) were not at increased risk of depleted iron stores (serum ferritin <15 μg/L; p = 0.340). Positive associations were observed between dietary iron and zinc intakes, and between iron and zinc status, however interpreting serum ferritin concentrations was not a useful proxy for estimating the likelihood of low serum zinc concentrations and women with depleted iron stores were not at increased risk of impaired zinc status in this cohort

Measurements and analysis of microwave nonlinearities in ferroelectric thin film transmission lines

This work evaluates the microwave nonlinear properties of ferroelectric BaSrTiO thin films by measuring the frequency response of several coplanar transmission lines and interdigital capacitor structures as a function of the applied electric field from 150 Hz to 40 GHz. From these measurements, we obtain the distributed nonlinear capacitance C(Vdc) as a function of dc bias. We also measure the harmonic generation at microwave frequencies in ferroelectric transmission lines, and use an accurate circuit model to obtain C(Vrf), the nonlinear capacitance as a function of RF bias. Information about the tuning speed of the film is obtained from a comparison between the two nonlinear capacitances. Characterization of this mechanism is also required to assess the spurious signal generation in ferroelectric-based devicesPeer Reviewe