The miscibility of calcium silicate perovskite and bridgmanite: A single perovskite solid solution in hot, iron-rich regions

Calcium silicate perovskite and bridgmanite are two phases believed to coexist throughout the lower mantle, which at some temperature, at least theoretically, dissolve into each other to form a single perovskite solid solution (Ca_{x}M_{1}−{x}_SiO_{3}). This may have large seismic and geochemical implications due to the changes in density, elasticity and element partition coefficients between single and mixed phase perovskites. DFT Molecular Dynamics has been used to estimate the miscibility of bridgmanite and calcium perovskite at pressures between 25 and 125 GPa. At 125 GPa (where mixing is the greatest in our pressure range) to mix 1% of Ca-pv into bridgmanite requires a temperature of 2042 K, 5% 2588 K, 10% 2675 K and 50% 2743 K. Therefore, in a simplified lower mantle chemistry an extensive MgSiO_{3}–CaSiO_{3} solid solution is not expected to occur. However, a simple model was employed to test whether the presence of other elements might influence this mutual solid solution and it was demonstrated that if sufficient concentrations (>1 at.%) of additional elements are present then miscibility may become favourable. Of the elements likely to be present at these concentrations it appears that ferrous iron promotes, whilst aluminium inhibits, a single-phase perovskite solid solution. To a lesser extent ferric iron may both increase and decrease perovskite miscibility. Modelling for realistic mantle compositions suggests that basaltic lithologies will always retain two perovskite components, whereas a single perovskite solid solution may be preferred in hot and/or iron-rich pyrolytic bulk compositions near the base of the lower mantle. Static calculations indicate perovskite miscibility may cause pyrolytic lithologies (with 12.5% CaSiO_{3}) to possess lower density (−0.14–0.25%), V_{s} (−1.5–3.5%) and V_{p} (−0.5–1.2%), and higher V_{Φ} (+ 0.00–0.75%) than predicted for assemblages containing two perovskites. These seismic changes, while preliminary, are similar to those observed in the LLSVPs which are also regions that are likely hotter than the surrounding mantle and thus possess conditions promoting the formation of a single perovskite phase

Human behaviour in emergency situations: comparisons between aviation and rail domains

This article presents a comparative review of the knowledge base regarding human behaviour in emergencies for both aviation and rail domains. Generic models of human behaviour in emergency situations are introduced and specific attention is then focussed on methods of behaviour prediction, exhibited behaviours in emergencies and methods of aiding evacuation across both modes of transport. Using established knowledge from the aviation domain, it has been possible to make observations and comparisons about the rail domain. Traditionally, the aviation domain has been a major focus of research attention and this is used to inform and interpret the rail domain. By drawing comparisons across these domains for human behaviour in emergency situations, the observations are discussed along with recommendations for future policies/planning for emergencies and future research areas

The Influence of Physiological Status on age Prediction of Anopheles Arabiensis Using Near Infra-red spectroscopy

Determining the age of malaria vectors is essential for evaluating the impact of interventions that reduce the survival of wild mosquito populations and for estimating changes in vectorial capacity. Near infra-red spectroscopy (NIRS) is a simple and non-destructive method that has been used to determine the age and species of Anopheles gambiae s.l. by analyzing differences in absorption spectra. The spectra are affected by biochemical changes that occur during the life of a mosquito and could be influenced by senescence and also the life history of the mosquito, i.e., mating, blood feeding and egg-laying events. To better understand these changes, we evaluated the influence of mosquito physiological status on NIR energy absorption spectra. Mosquitoes were kept in individual cups to permit record keeping of each individual insect’s life history. Mosquitoes of the same chronological age, but at different physiological stages, were scanned and compared using cross-validations. We observed a slight trend within some physiological stages that suggest older insects tend to be predicted as being physiologically more mature. It was advantageous to include mosquitoes of different chronological ages and physiological stages in calibrations, as it increases the robustness of the model resulting in better age predictions. Progression through different physiological statuses of An. arabiensis influences the chronological age prediction by the NIRS. Entomologists that wish to use NIR technology to predict the age of field-caught An. gambiae s.l from their study area should use a calibration developed from their field strain using mosquitoes of diverse chronological ages and physiological stages to increase the robustness and accuracy of the predictions.\u

SARS-CoV-2-specific memory B cells can persist in the elderly who have lost detectable neutralising antibodies

Memory B cells (MBC) can provide a recall response able to supplement waning antibodies with an affinity-matured response better able to neutralise variant viruses. We studied a cohort of elderly care home residents and younger staff (median age 87yrs and 56yrs respectively) who had survived COVID-19 outbreaks with only mild/asymptomatic infection. The cohort was selected to enrich for a high proportion who had lost neutralising antibodies (nAb), to specifically investigate the reserve immunity from SARS-CoV-2-specific MBC in this setting. Class-switched spike and RBD-tetramer-binding MBC persisted five months post-mild/asymptomatic SARS-CoV-2 infection, irrespective of age. The majority of spike/RBD-specific MBC had a classical phenotype but activated memory B cells, that may indicate ongoing antigenic stimulation or inflammation, were expanded in the elderly. Spike/RBD-specific MBC remained detectable in the majority who had lost nAb, although at lower frequencies and with a reduced IgG/IgA isotype ratio. Functional spike/S1/RBD-specific recall was also detectable by ELISpot in some who had lost nAb, but was significantly impaired in the elderly. Our findings demonstrate a reserve of SARS-CoV-2-specific MBC persists beyond loss of nAb, but highlight the need for careful monitoring of functional defects in spike/RBD-specific B cell immunity in the elderly

Genetic parameters for social effects on survival in cannibalistic layers: Combining survival analysis and a linear animal model

<p>Abstract</p> <p>Background</p> <p>Mortality due to cannibalism in laying hens is a difficult trait to improve genetically, because censoring is high (animals still alive at the end of the testing period) and it may depend on both the individual itself and the behaviour of its group members, so-called associative effects (social interactions). To analyse survival data, survival analysis can be used. However, it is not possible to include associative effects in the current software for survival analysis. A solution could be to combine survival analysis and a linear animal model including associative effects. This paper presents a two-step approach (2STEP), combining survival analysis and a linear animal model including associative effects (LAM).</p> <p>Methods</p> <p>Data of three purebred White Leghorn layer lines from Institut de Sélection Animale B.V., a Hendrix Genetics company, were used in this study. For the statistical analysis, survival data on 16,780 hens kept in four-bird cages with intact beaks were used. Genetic parameters for direct and associative effects on survival time were estimated using 2STEP. Cross validation was used to compare 2STEP with LAM. LAM was applied directly to estimate genetic parameters for social effects on observed survival days.</p> <p>Results</p> <p>Using 2STEP, total heritable variance, including both direct and associative genetic effects, expressed as the proportion of phenotypic variance, ranged from 32% to 64%. These results were substantially larger than when using LAM. However, cross validation showed that 2STEP gave approximately the same survival curves and rank correlations as LAM. Furthermore, cross validation showed that selection based on both direct and associative genetic effects, using either 2STEP or LAM, gave the best prediction of survival time.</p> <p>Conclusion</p> <p>It can be concluded that 2STEP can be used to estimate genetic parameters for direct and associative effects on survival time in laying hens. Using 2STEP increased the heritable variance in survival time. Cross validation showed that social genetic effects contribute to a large difference in survival days between two extreme groups. Genetic selection targeting both direct and associative effects is expected to reduce mortality due to cannibalism in laying hens.</p

The high comorbidity burden of the hepatitis C virus infected population in the United States

<p>Abstract</p> <p>Background</p> <p>Chronic hepatitis C (HCV) disease can be complicated with comorbid conditions that may impact treatment eligibility and outcomes. The aim of the study was to systematically review comorbidities and symptoms in an HCV infected population, specifically assessing comorbidities associated with HCV anti-viral treatment and disease, as well as comparing comorbidities between an HCV infected and uninfected control population.</p> <p>Methods</p> <p>This was a retrospective cohort study within a United States medical claims database among patients with chronic HCV designed to estimate the two-year period prevalence of comorbidities. Patients with two HCV diagnosis codes, 24 months of continuous health insurance coverage, and full medical and pharmacy benefits were included.</p> <p>Results</p> <p>Among a chronic HCV cohort of 7411 patients, at least one comorbid condition was seen in almost all patients (> 99%) during the study period. HCV-infected patients reported almost double the number of comorbidities compared to uninfected controls. Of the 25 most common comorbidities, the majority of the comorbidities (n = 22) were known to be associated with either HCV antiviral treatment or disease. The five most frequent comorbidities were liver disease [other] (37.5%), connective tissue disease (37.5%), abdominal pain (36.1%), upper respiratory infections (35.6%), and lower respiratory disease (33.7%). Three notable comorbidities not known to be associated with antiviral treatment or disease were benign neoplasms (24.3%), genitourinary symptoms & ill-defined conditions (14.8%), and viral infections (13.8%).</p> <p>Conclusions</p> <p>This US medically insured HCV population is highly comorbid. Effective strategies to manage these comorbidities are necessary to allow wider access to HCV treatment and reduce the future burden of HCV disease and its manifestations.</p

Multiple ITS Copies Reveal Extensive Hybridization within Rheum (Polygonaceae), a Genus That Has Undergone Rapid Radiation

During adaptive radiation events, characters can arise multiple times due to parallel evolution, but transfer of traits through hybridization provides an alternative explanation for the same character appearing in apparently non-sister lineages. The signature of hybridization can be detected in incongruence between phylogenies derived from different markers, or from the presence of two divergent versions of a nuclear marker such as ITS within one individual.In this study, we cloned and sequenced ITS regions for 30 species of the genus Rheum, and compared them with a cpDNA phylogeny. Seven species contained two divergent copies of ITS that resolved in different clades from one another in each case, indicating hybridization events too recent for concerted evolution to have homogenised the ITS sequences. Hybridization was also indicated in at least two further species via incongruence in their position between ITS and cpDNA phylogenies. None of the ITS sequences present in these nine species matched those detected in any other species, which provides tentative evidence against recent introgression as an explanation. Rheum globulosum, previously indicated by cpDNA to represent an independent origin of decumbent habit, is indicated by ITS to be part of clade of decumbent species, which acquired cpDNA of another clade via hybridization. However decumbent and glasshouse morphology are confirmed to have arisen three and two times, respectively.These findings suggested that hybridization among QTP species of Rheum has been extensive, and that a role of hybridization in diversification of Rheum requires investigation

Seasonal Growth Rate of the Sponge Haliclona oculata (Demospongiae: Haplosclerida)

The interest in sponges has increased rapidly since the discovery of potential new pharmaceutical compounds produced by many sponges. A good method to produce these compounds by using aquaculture of sponges is not yet available, because there is insufficient knowledge about the nutritional needs of sponges. To gain more insight in the nutritional needs for growth, we studied the growth rate of Haliclona oculata in its natural environment and monitored environmental parameters in parallel. A stereo photogrammetry approach was used for measuring growth rates. Stereo pictures were taken and used to measure volumetric changes monthly during 1 year. Volumetric growth rate of Haliclona oculata showed a seasonal trend with the highest average specific growth rate measured in May: 0.012 ± 0.004 day−1. In our study a strong positive correlation (p < 0.01) was found for growth rate with temperature, algal biomass (measured as chlorophyll a), and carbon and nitrogen content in suspended particulate matter. A negative correlation (p < 0.05) was found for growth rate with salinity, ammonium, nitrate, nitrite, and phosphate. No correlation was found with dissolved organic carbon, suggesting that Haliclona oculata is more dependent on particulate organic carbon

Persistence of accuracy of genomic estimated breeding values over generations in layer chickens

<p>Abstract</p> <p>Background</p> <p>The predictive ability of genomic estimated breeding values (GEBV) originates both from associations between high-density markers and QTL (Quantitative Trait Loci) and from pedigree information. Thus, GEBV are expected to provide more persistent accuracy over successive generations than breeding values estimated using pedigree-based methods. The objective of this study was to evaluate the accuracy of GEBV in a closed population of layer chickens and to quantify their persistence over five successive generations using marker or pedigree information.</p> <p>Methods</p> <p>The training data consisted of 16 traits and 777 genotyped animals from two generations of a brown-egg layer breeding line, 295 of which had individual phenotype records, while others had phenotypes on 2,738 non-genotyped relatives, or similar data accumulated over up to five generations. Validation data included phenotyped and genotyped birds from five subsequent generations (on average 306 birds/generation). Birds were genotyped for 23,356 segregating SNP. Animal models using genomic or pedigree relationship matrices and Bayesian model averaging methods were used for training analyses. Accuracy was evaluated as the correlation between EBV and phenotype in validation divided by the square root of trait heritability.</p> <p>Results</p> <p>Pedigree relationships in outbred populations are reduced by 50% at each meiosis, therefore accuracy is expected to decrease by the square root of 0.5 every generation, as observed for pedigree-based EBV (Estimated Breeding Values). In contrast the GEBV accuracy was more persistent, although the drop in accuracy was substantial in the first generation. Traits that were considered to be influenced by fewer QTL and to have a higher heritability maintained a higher GEBV accuracy over generations. In conclusion, GEBV capture information beyond pedigree relationships, but retraining every generation is recommended for genomic selection in closed breeding populations.</p