Mechanisms and Prevention of Lead Sulphide (PbS) Scale Deposition in Multiphase Systems

The deposition of mineral scale poses a major challenge in the oil and gas industry, where flow assurance issues can result in significant operating costs and well downtime. This study aimed to analyse the mechanisms of precipitation and deposition for a range of scale types (calcium carbonate, barium sulphate and lead sulphide) in simple and complex systems. Whilst traditionally, studies looking to mitigate mineral scaling have investigated precipitation and deposition in single phase brines, the introduction of a light oil phase to induce multiphase conditions in this study was representative of processes occurring within oilfield production systems. A rig that enabled the propagation of turbulent, multiphase, emulsion-forming flow within a H2S environment was designed and constructed in order to assess the interaction of bulk colloids at the oil-water interface and consequently the mechanism by which they deposited upon surfaces. Characterisation of solid stabilised Pickering emulsions took place through optical microscopy and cryo-scanning electron microscopy (cryo-SEM). As a secondary objective, the mitigation efficacy of a number of anti-fouling coatings was assessed under a range of scaling conditions, with physiochemical characteristics inherent to the surfaces that prevented initial deposition identified. Fluoropolymers, diamond-like-carbon (DLC) and sol-gel coatings, were found to be the most promising anti-fouling substrates and as such were assessed for potential application into oilfield systems and equipment. Scaling severity was measured through mass gain analysis and SEM of surface crystals to establish morphology and coverage. The relationship between coating wettability and scale adhesion was explored using atomic force microscopy (AFM), where the interfacial forces acting upon hydrophilic and hydrophobic tips when in contact with a cleaved [001] galena face. Results showed that whilst attractive hydrophobic force had a bearing on PbS deposition on hydrophobic surfaces in single phase, the presence of a light oil phase in multiphase systems was pre-dominant in determining scaling likelihood upon surfaces. The oil wetting of hydrophobic surfaces was seen to largely prevent the deposition of bulk precipitated scale, with a relationship found between the thermodynamics of precipitation of a species and the degree of accuracy to which scaling could be predicted upon surfaces of varying wettability

Gait speed characteristics and Its spatiotemporal determinants in nursing home residents: A cross-sectional study

Fien, S ORCiD: 0000-0003-0181-5458BACKGROUND AND PURPOSE: Low and slowing gait speeds among nursing home residents are linked to a higher risk of disability, cognitive impairment, falls, and mortality. A better understanding of the spatiotemporal parameters of gait that influence declining mobility could lead to effective rehabilitation and preventative intervention. The aims of this study were to objectively quantify the spatiotemporal characteristics of gait in the nursing home setting and define the relationship between these parameters and gait speed. METHODS: One hundred nursing home residents were enrolled into the study and completed 3 habitual gait speed trials over a distance of 3.66 m. Trials were performed using an instrumented gait analysis. The manner in which the spatiotemporal parameters predicted gait speed was examined by univariate and multivariable regression modeling. RESULTS: The nursing home residents had a habitual mean (SD) gait speed of 0.63 (0.19) m/s, a stride length of 0.83 (0.15) m, a support base of 0.15 (0.06) m, and step time of 0.66 (0.12) seconds. Multivariable linear regression revealed stride length, support base, and step time predicted gait speed (R = 0.89, P < .05). Step time had the greatest influence on gait speed, with each 0.1-second decrease in step time resulting in a 0.09 m/s (95% confidence interval, 0.08-0.10) increase in habitual gait speed. CONCLUSIONS: This study revealed step time, stride length, and support base are the strongest predictors of gait speed among nursing home residents. Future research should concentrate on developing and evaluating intervention programs that were specifically designed to focus on the strong predictors of gait speed in nursing home residents. We would also suggest that routine assessments of gait speed, and if possible their spatiotemporal characteristics, be done on all nursing home residents in an attempt to identify residents with low or slowing gait speed

Desensitization to medical examining equipment through learner control in a child with severe mental retardation

While the psychological literature is replete with examples of desensitization to phobic stimuli, few studies have documented successful interventions conducted with individuals identified as mentally retarded. The study describes desensitization to basic medical examining equipment in a youngster with severe mental retardation and autistic tendencies. Following desensitization to feared stimuli through the repeated exposure of baseline, intervention was initiated on the remaining feared stimuli through a learner control technique which combined modeling, behavioral rehearsal, and a variation of contact desensitization (Ritter, 1968). Results of a return-to-baseline design suggested that the medical examinations feared most by the child were of the same functional response class and that they did respond positively to intervention. Discussion of the methods and results provides practical implications for health professionals as well as offering hypotheses regarding the potential communicative and adaptive functions phobic manifestations serve in persons who experience significant handicapping conditions

Accurate performance measurement of silicon solar cells

erformance measurement is an important part of the solar cell manufacturing process. Two classes of measurement can be considered: accurate calibration – for the creation of reference cells and the setting of records; and routine measurement – for cell sorting and process improvement. This work describes techniques that address both issues – an accurate calibration technique using natural sunlight, and a routine measurement technique using a xenon flashlamp. Both techniques are low-cost, yet in combination they achieve very good accuracy. The light source is very important when calibrating solar cells. Commonly used light sources – good quality solar simulators – are expensive and frequently inaccurate. This work shows that testing of solar cells under natural sunlight is simpler, cheaper, more accurate, and more reliable than all but the most careful simulator measurements. Periodic outdoor calibrations under natural sunlight can therefore eliminate the need for an expensive solar simulator and greatly reduce the need for calibration at standards labs. Solar spectra generated with the model SMARTS2 show that the direct solar spectrum, under clear sky and low air-mass conditions, is an excellent match to the AM1.5G standard spectrum – dramatically better than simulators costing US$20,000 or more. Millions of simulations of a broad range of silicon cells (efficiencies 6-25under the modelled direct spectra show that measurement errors of less than 5achievable. This is comparable to the reproducibility of results achieved by national standards laboratories. Climate data shows that the required atmospheric conditions occur commonly in summer for all but polar latitudes. Experimental verification of the modelling is encouraging but not yet conclusive. The outcome of the research is a testing ‘recipe’ that uses low-cost equipment and gives an estimate of measurement uncertainty. For routine measurement of large numbers of solar cells, an indoor solar simulator is essential. While simulators can introduce large measurement errors, most of these errors can be eliminated by using a reference cell that is well matched to the test cells. The use of a simpler, lower-cost simulator is possible since reference cells can easily be calibrated under natural sunlight. The second half of this work describes the design of a low cost flash-lamp solar simulator. Most conventional flash testing systems maintain constant light intensity while rapidly sweeping out the I-V curve of the cell. This method has two disadvantages – it requires a flash that is specially engineered to produce constant light output, and the rapid change in cell bias-voltage causes transient errors. The new approach developed in this work essentially does the reverse – it maintains a constant bias voltage on the cell while allowing the light level to vary. This allows the use of a commercial xenon flash, and reduces sensitivity to transient errors. In addition, it extracts a family of I-V curves at different light intensities, whereas the conventional approach only extracts a single I-V curve. The new design has been implemented, using commercial-off-theshelf equipment costing less than US$10,000, and it works well. One of these systems is in use at the Centre for Sustainable Energy Systems, ANU, where it has tested tens of thousands of concentrator cells. A second system has been sold to BP Solar, UK

Polyploidy breaks speciation barriers in Australian burrowing frogs Neobatrachus

Polyploidy has played an important role in evolution across the tree of life but it is still unclear how polyploid lineages may persist after their initial formation. While both common and well-studied in plants, polyploidy is rare in animals and generally less understood. The Australian burrowing frog genus Neobatrachus is comprised of six diploid and three polyploid species and offers a powerful animal polyploid model system. We generated exome-capture sequence data from 87 individuals representing all nine species of Neobatrachus to investigate species-level relationships, the origin and inheritance mode of polyploid species, and the population genomic effects of polyploidy on genus-wide demography. We describe rapid speciation of diploid Neobatrachus species and show that the three independently originated polyploid species have tetrasomic or mixed inheritance. We document higher genetic diversity in tetraploids, resulting from widespread gene flow between the tetraploids, asymmetric inter-ploidy gene flow directed from sympatric diploids to tetraploids, and isolation of diploid species from each other. We also constructed models of ecologically suitable areas for each species to investigate the impact of climate on differing ploidy levels. These models suggest substantial change in suitable areas compared to past climate, which correspond to population genomic estimates of demographic histories. We propose that Neobatrachus diploids may be suffering the early genomic impacts of climate-induced habitat loss, while tetraploids appear to be avoiding this fate, possibly due to widespread gene flow. Finally, we demonstrate that Neobatrachus is an attractive model to study the effects of ploidy on the evolution of adaptation in animals

Prevalence and Risk Factors for Low Habitual Walking Speed in Nursing Home Residents: An Observational Study

Objective To quantify habitual walking speed and estimate the prevalence of low habitual walking speed

MRI atlas of a lizard brain

Magnetic resonance imaging (MRI) is an established technique for neuroanatomical analysis, being particularly useful in the medical sciences. However, the application of MRI to evolutionary neuroscience is still in its infancy. Few magnetic resonance brain atlases exist outside the standard model organisms in neuroscience and no magnetic resonance atlas has been produced for any reptile brain. A detailed understanding of reptilian brain anatomy is necessary to elucidate the evolutionary origin of enigmatic brain structures such as the cerebral cortex. Here, we present a magnetic resonance atlas for the brain of a representative squamate reptile, the Australian tawny dragon (Agamidae: Ctenophorus decresii), which has been the subject of numerous ecological and behavioral studies. We used a high-field 11.74T magnet, a paramagnetic contrasting-enhancing agent and minimum-deformation modeling of the brains of thirteen adult male individuals. From this, we created a high-resolution three-dimensional model of a lizard brain. The 3D-MRI model can be freely downloaded and allows a better comprehension of brain areas, nuclei, and fiber tracts, facilitating comparison with other species and setting the basis for future comparative evolution imaging studies. The MRI model and atlas of a tawny dragon brain (Ctenophorus decresii) can be viewed online and downloaded using the Wiley Biolucida Server at wiley.biolucida.net.Government of Australia, Grant/Award Numbers: APA#31/2011, IPRS#1182/2010; National Science and Engineering Research Council of Canada, Grant/Award Number: PGSD3-415253-2012; Quebec Nature and Technology Research Fund, Grant/AwardNumber: 208332; National Imaging Facility of Australia; Spanish Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional, Grant/Award Number:BFU2015-68537-

CE14016

In the southwest of Ireland and the Celtic Sea (ICES Divisions VIIaS, g & j),herring acoustic surveys have been carried out since 1989. This survey was undertaken in early October. The geographical confines of the annual 21 day survey program have been modified in recent years to include areas to the south of the main winter spawning grounds in an effort to identify the whereabouts of winter spawning fish before the annual inshore spawning migration. Spatial resolution of acoustic transects has been increased over the entire south coast survey area. The acoustic component of the survey has been further complimented since 2004 by detailed hydrographic and marine mammal and seabird surveys

Comparative effectiveness of BNT162b2 versus mRNA-1273 covid-19 vaccine boosting in England: matched cohort study in OpenSAFELY-TPP

Objective To compare the effectiveness of the BNT162b2 mRNA (Pfizer-BioNTech) and mRNA-1273 (Moderna) covid-19 vaccines during the booster programme in England. Design Matched cohort study, emulating a comparative effectiveness trial. Setting Linked primary care, hospital, and covid-19 surveillance records available within the OpenSAFELY-TPP research platform, covering a period when the SARS-CoV-2 delta and omicron variants were dominant. Participants 3 237 918 adults who received a booster dose of either vaccine between 29 October 2021 and 25 February 2022 as part of the national booster programme in England and who received a primary course of BNT162b2 or ChAdOx1. Intervention Vaccination with either BNT162b2 or mRNA-1273 as a booster vaccine dose. Main outcome measures Recorded SARS-CoV-2 positive test, covid-19 related hospital admission, covid-19 related death, and non-covid-19 related death at 20 weeks after receipt of the booster dose. Results 1 618 959 people were matched in each vaccine group, contributing a total 64 546 391 person weeks of follow-up. The 20 week risks per 1000 for a positive SARS-CoV-2 test were 164.2 (95% confidence interval 163.3 to 165.1) for BNT162b2 and 159.9 (159.0 to 160.8) for mRNA-1273; the hazard ratio comparing mRNA-1273 with BNT162b2 was 0.95 (95% confidence interval 0.95 to 0.96). The 20 week risks per 1000 for hospital admission with covid-19 were 0.75 (0.71 to 0.79) for BNT162b2 and 0.65 (0.61 to 0.69) for mRNA-1273; the hazard ratio was 0.89 (0.82 to 0.95). Covid-19 related deaths were rare: the 20 week risks per 1000 were 0.028 (0.021 to 0.037) for BNT162b2 and 0.024 (0.018 to 0.033) for mRNA-1273; hazard ratio 0.83 (0.58 to 1.19). Comparative effectiveness was generally similar within subgroups defined by the primary course vaccine brand, age, previous SARS-CoV-2 infection, and clinical vulnerability. Relative benefit was similar when vaccines were compared separately in the delta and omicron variant eras. Conclusions This matched observational study of adults estimated a modest benefit of booster vaccination with mRNA-1273 compared with BNT162b2 in preventing positive SARS-CoV-2 tests and hospital admission with covid-19 20 weeks after vaccination, during a period of delta followed by omicron variant dominance