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X-ray fluorescence as a method of chemical analysis has been receiving considerable attention due to its inherent advantages of being non-destructive and generally less time consuming than conventional methods. A method of analysis is described using a pulse height analyzer in conjunction with the X-ray fluorescent unit which further extends the range of analysis.
This combination was used to measure tin in steel as low as .01% to an accuracy of .003%. Other similar analyses are suggested.
Accurate identification of individuals at high risk of surgical site infections (SSIs) or periprosthetic joint infections (PJIs) influences clinical decisions and development of preventive strategies. We aimed to determine progress in the development and validation of risk prediction models for SSI or PJI using a systematic review. We searched for studies that have developed or validated a risk prediction tool for SSI or PJI following joint replacement in MEDLINE, EMBASE, Web of Science and Cochrane databases; trial registers and reference lists of studies up to September 2016. Nine studies describing 16 risk scores for SSI or PJI were identified. The number of component variables in a risk score ranged from 4 to 45. The C-index ranged from 0·56 to 0·74, with only three risk scores reporting a discriminative ability of >0·70. Five risk scores were validated internally. The National Healthcare Safety Network SSIs risk models for hip and knee arthroplasties (HPRO and KPRO) were the only scores to be externally validated. Except for HPRO which shows some promise for use in a clinical setting (based on predictive performance and external validation), none of the identified risk scores can be considered ready for use. Further research is urgently warranted within the field.
The Southern Ocean is the largest of the high-nutrient, low-chlorophyll (HNLC) regions of the world ocean. Phytoplankton production fails to utilise completely the pool of inorganic nutrients in the euphotic zone, giving rise to low phytoplankton bio-mass and leaving relatively high summer nutrient concentrations. This enigma is of considerable significance for our understanding of the role of the oceans in the global carbon cycle. Various limiting factors have been considered: low light, low temperature, absence of necessary trace elements, grazing pressure and other means of biomass removal.
The dynamics of nitrogen uptake by phytoplankton are of particular importance. Classically, nitrate mixed into the surface layer during winter provides the nitrogen pool for growth in the spring bloom. Some organic material is exported to depth, whilst the remainder is recycled, providing ammonium and other reduced species as nitrogenous substrates for growth during the remainder of the season. The oxidation state of the inorganic nitrogen supply thus identifies new and recycled carbon fixation. Whilst this is convenient “shorthand” for the nitrogen nutrition of carbon export in much of the ocean, it is an inappropriate model for the Southern Ocean. Here, nitrate and ammonium use are simultaneous, and nitrate is never exhausted by the annual phytoplankton production.
We speculate that a range of environmental factors combine to make the large pool of nitrate partially inaccessible to phytoplankton. in addition to the documented effects of low iron availability and high ammonium concentrations, the low temperatures characteristic of the Southern Ocean may decrease nitrate availability because of the increased energetic overheads in its uptake and reduction. This in turn makes ammonium an important nitrogenous substrate, and its production by zooplankton and heterotrophic microorganisms is an important component of the plankton nitrogen cycle. There is some evidence that ammonium production by large grazing animals may stimulate phytoplankton growth. Microbial removal of nitrogen from sedimenting phytoplankton cells may result in local decoupling between the carbon and nitrogen cycles, allowing some reduced nitrogen to remain in the euphotic zone whilst carbon is exported to depth.
The pea leaf weevil, Sitona lineatus (Linnaeus) (Coleoptera: Curculionidae), is an important pest of field peas, Pisum sativum Linnaeus (Fabaceae), and faba beans, Vicia faba Linnaeus (Fabaceae), that has recently become established in the Prairie Provinces of Canada. Male pea leaf weevils produce an aggregation pheromone, 4-methyl-3,5-heptanedione, in the spring when overwintered weevils migrate to fields to feed and mate. The current study tests the attractiveness of the aggregation pheromone with and without synthetic bean volatiles to pea leaf weevils in the spring and in the fall when weevils seek perennial legumes to feed and overwinter. Modified Leggett traps similar to those used in Europe did not retain weevils in this study. Aggregation pheromone-baited pitfall traps caught male and female weevils in the spring and fall. Weevils were not attracted to traps baited with three bean volatiles, (Z)-3-hexen-1-yl acetate, (Z)-3-hexen-1-ol, and linalool. Bean volatiles did enhance response to pheromone, but only in the fall. Weevils were captured in most semiochemical-baited traps in a 1:1 sex ratio, but female-biased catch in control traps might indicate greater activity of females in the trap vicinity. This study lays the groundwork for semiochemical-based monitoring to detect pea leaf weevil spread in the Prairie Provinces.
Background: For adolescents with epilepsy, there is often a poor system in place to meet their individualized transition needs. Our objectives were 1) to develop epilepsy-specific transition care management plans (TCMPs) to ensure access, and attachment to adult healthcare providers, and 2) to identify strategies for providing support during the transition period, including through the development of physician and patient (or caregiver) navigated web-based tools, resources and recommendations for health system improvements. Methods: Physicians and nurses with expertise in areas including adult and pediatric epilepsy, family medicine, psychiatry, and varied allied health professionals were engaged to generate epilepsy-related TCMPs. Results: Through an iterative process spanning the course of over a year, TCMPs were developed to cover areas including: treatment responsive and resistant epilepsy, ketogenic diet, epilepsy surgery, women’s issues, mental health, and psychosocial aspects of epilepsy. The TCMPs referenced established guidelines and best practices in the literature wherever possible. Caregiver roles and responsibilities were outlined, remaining cognoscent of available provincial resources. Conclusions: Epilepsy specific TCMPs can be developed through a collaborative approach between pediatric and adult healthcare providers, easing the patient experience, creating educated accountability, and providing a forum to identify and address gaps of care in adolescents with epilepsy.
Feline degenerative joint disease causes pain and disability and therefore represents a welfare concern for captive animals. Alternatives to traditional pharmaceutical therapies are gaining popularity and this study aimed to evaluate the efficacy of an egg-shell membrane therapy in captive cheetahs and leopards. Seven animals were treated with SteadfastTM and monitored for radiographic changes (n = 6) and lameness score (n = 7) over a 42 day period. A reduction in lameness was determined over the course of the study (p = 0.01), and improved orthopaedic status detected in 50% (3/6) of animals via radiographic examination. Surprisingly, a negative dose response was detected, whereby animals receiving lower doses exhibited the most marked changes in lameness score. Despite the small sample size and subjective scoring of lameness, this preliminary study demonstrates the need for further investigation into the use of an eggshell membrane-based supplement to improve mobility in captive felids with degenerative joint disease.
The Early Iron Age enclosures and associated sites on Sutton Common on the western edge of the Humberhead Levels contain an exceptional variety of archaeological data of importance not only to the region but for the study of later prehistory in the British Isles. Few other later prehistoric British sites outside the East Anglian fens and the Somerset Levels have thus far produced the quantity and quality of organically preserved archaeological materials that have been found, despite the small scale of the investigations to date. The excavations have provided an opportunity to integrate a variety of environmental analyses, of wood, pollen, beetles, waterlogged and carbonised plant remains, and of soil micromorphology, to address archaeological questions about the character, use, and environment of this Early Iron Age marsh fort. The site is comprised of a timber palisaded enclosure and a succeeding multivallate enclosure linked to a smaller enclosure by a timber alignment across a palaeochannel, with associated finds ranging in date from the Middle Bronze Age to the Roman and medieval periods. Among the four adjacent archaeological sites is an Early Mesolithic occupation site, also with organic preservation, and there is a Late Neolithic site beneath the large enclosure. Desiccation throughout the common is leading to the damage and loss of wooden and organic remains. It is hoped that the publication of these results, of investigations between 1987 and 1993, will lead to a fuller investigation taking place.
Bombardment damage produced by Si+ ions in AlxGa1−xAs/GaAs layer structures has been studied using transmission electron microscopy and ion channeling and backscattering spectrometry. The damage resistance of A1xGa1−xAs alloy layers increases with Al concentration. In particular, by comparison of complementary Si+ ion doses yielding similar nuclear displacement densities at 150keV and 2MeV bombardment energies, it is demonstrated for the first time that the local concentration of implanted Si impurity is likely to be a significant factor in controlling lattice damage build-up, especially for the highest Si+ ion implantation doses. It is also shown that, in a manner analogous to A1As, the alloy layers can confer a significant protection from ion damage upon adjacent, epitaxially-bonded narrow zones of crystalline GaAs.
The implantation of Ar+ ions into AlAs/GaAs layered samples is shown to give very different damage structures in the two materials. While the GaAs is relatively easily amorphised, the AlAs is quite resistant to damage accumulation and remains crystalline for the ion doses employed in these investigations. The behaviour of the different damage structures when subjected to rapid thermal annealing treatments is described in some detail. It is demonstrated that differences in the initial damage state have a strong influence upon the nature of lattice defects produced by annealing.
The contrast of misfit dislocations in an InGaAs layer, close to the critical thickness and capped with GaAs grown by MBE on a (001) oriented GaAs substrate has been investigated by double axis synchrotron X-radiation topography. The layer thickness variation as a function of position has been measured to a precision of 1A by matching interference fringes observed in the 004 symmetric reflection double crystal rocking curves with simulations. The misfit dislocation density is highly anisotropic, varying from zero to a high value with increasing thickness. The contrast of the dislocations in the 004, 224 and 044 reflections has been examined in detail. All of the long dislocation segments characterized were 60° in character with ½<110> Burgers vectors inclined to the specimen surface. No dislocations were found which did not appear to be of this type. A surprising difference in contrast of the background in the 224 and 224 reflections is discussed.
Plague, which is most often caused by the bite of Yersinia pestis-infected fleas, is a rapidly progressing, serious disease that can be fatal without prompt antibiotic treatment. In late December 2007, an outbreak of acute gastroenteritis occurred in Nimroz Province of southern Afghanistan. Of the 83 probable cases of illness, 17 died (case fatality 20·5%). Being a case was associated with consumption or handling of camel meat (adjusted odds ratio 4·4, 95% confidence interval 2·2–8·8, P<0·001). Molecular testing of patient clinical samples and of tissue from the camel using PCR/electrospray ionization–mass spectrometry revealed DNA signatures consistent with Yersinia pestis. Confirmatory testing using real-time PCR and immunological seroconversion of one of the patients confirmed that the outbreak was caused by plague, with a rare gastrointestinal presentation. The study highlights the challenges of identifying infectious agents in low-resource settings; it is the first reported occurrence of plague in Afghanistan.
Assessment tools and frameworks have been developed that allow environmental assessments to be conducted and which can be used to demonstrate whether non-human species are protected from the impact of exposure to ionising radiation released under regulation. Frameworks are often tiered, increasing in the level of complexity, input data requirements and need for expert involvement as the assessment moves to successively higher tiers. These are, conceptually, similar to assessment approaches available for chemical risk assessment. What criteria (e.g. numeric benchmarks) should be used, and how these should be defined, are currently under debate, but it is likely that use will be made of approaches developed for setting assessment criteria for chemicals. However it will be necessary to ensure that any assessment criteria developed are fit for use in a regulatory context. This paper reviews the similarities and differences between regulation of, and assessment methods for, chemicals and radioactive substances and presents recommendations regarding how components of chemicals risk assessment may be adopted for radioactive substances.
The relationship between plutonic and volcanic rocks is central to understanding the geochemical evolution of silicic magma systems, but it is clouded by ambiguities associated with unravelling the plutonic record. Here we report an integrated U–Pb, O and Lu–Hf isotope study of zircons from three putative granitic–volcanic rock pairs from the Lachlan Fold Belt, southeastern Australia, to explore the connection between the intrusive and extrusive realms. The data reveal contrasting petrogenetic scenarios for the S- and I-type pairs. The zircon Hf–O isotope systematics in an I-type dacite are very similar to those of their plutonic counterpart, supporting an essentially co-magmatic relationship between these units. The elevated δ18O of zircons in these I-type rocks confirm a significant supracrustal source component. The S-type volcanic rocks are not the simple erupted equivalents of the granites, although the extrusive and plutonic units can be related by open-system magmatic evolution. Zircons in the S-type rocks define covariant εHf–δ18O arrays that attest to mixing or assimilation processes between two components, one being the Ordovician metasedimentary country rocks, the other either an I-type magma or a mantle-derived magma. The data are consistent with models involving incremental melt extraction from relatively juvenile magmas undergoing open-system differentiation at depth, followed by crystal-liquid mixing upon emplacement in shallow magma reservoirs, or upon eruption. The latter juxtaposes crystals with markedly different petrogenetic histories and determines whole-rock geochemical and textural properties. This scenario can explain the puzzling decoupling between the bulk rock isotope and geochemical compositions commonly observed for granite suites.
In spherical symmetry, very reliable models of stellar core collapse, bounce, and the postbounce phase can be constructed based on general relativistic Boltzmann neutrino transport. However, even if the time-integrated neutrino luminosity in the region between the surface of the protoneutron star and the stalled accretion shock is one or two orders of magnitude larger than the energy of a supernova explosion, it is generally accepted that the net energy transfer is not efficient enough to drive an explosion, unless the fluid instabilities in this regime are taken into account. Complementary to other groups, who are elaborating an extension of the accurate neutrino physics to axisymmetric simulations, we construct efficient parameterizations of the neutrino physics that enable three-dimensional magneto-hydrodynamics simulations that do not constrain the fluid instabilities by artificially imposed symmetries. We evaluate our approximations with respect to spherically symmetric Boltzmann neutrino transport, present preliminary MHD simulations with a resolution of 600 zones cubed, and illustrate the questions that can be addressed by this approach.
This report, which was sponsored by the Life Board of the Faculty and Institute of Actuaries, was originally published in November 1997.
Because it is referred to several times in the paper ‘Reserving, Pricing and Hedging for Policies with Guaranteed Annuity Options’, and in the discussions of the paper, and because it is not easily accessible elsewhere, it is printed here as a background paper for reference.
Central pontine myelinolysis (CPM) is rare in childhood with only a few cases reported in world literature. We report a 7-year-old male who presented with acute ataxia, swallowing difficulties, dysarthria, and radiological features consistent with the disorder. He improved remarkably with oral prednisolone therapy and was almost back to normal by 2 weeks. A review of the literature is also included.
The incidence of childhood autism and other autistic spectrum disorders (ASDs) in preschool children was determined for two areas of the West Midlands between 1991 and 1996. Children diagnosed before the age of 5 years and residing within the study areas at diagnosis were detected from the records of four child development centres. The incidence rate per 10000 children per year for the combined areas was 8.3 for all children with ASDs, 3.5 for classical childhood autism (CA), and 4.8 for other ASDs. Rates were similar in both areas, despite differences in social deprivation and proportions of ethnic minorities. While rates for classical CA increased by 18% per year, a much larger increase (55% per year) was seen for ‘other ASDs’, suggesting that clinicians are becoming increasingly able and/or willing to diagnose ASDs in preschool children.