1,821 research outputs found

    Lupin growth and water use; wheat, barley, pea

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    84C16/84C17 Lupin Growth and Water Use. 84C19 Effect of Density and Nitrogen on Growth and Yield of Uniculm and Tillering Wheat. 84C20 Maturity, Nitrogen and Density Effects of Barley. 84C21 Wheat Variety Trial. 84C18/23/28/33 Pea Research in the Geraldton Region. 84C32 Effect of Terra Sorb on Wheat Yield

    Maximum Power Point Tracking for Cascaded PV-Converter Modules Using Two-Stage Particle Swarm Optimization

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    The paper presents a novel two-stage particle swarm optimization (PSO) for the maximum power point tracking (MPPT) control of a PV system consisting of cascaded PV-converter modules, under partial shading conditions (PSCs). In this scheme, the grouping method of the shuffled frog leaping algorithm (SFLA) is incorporated with the basic PSO algorithm, ensuring fast and accurate searching of the global extremum. An adaptive speed factor is also introduced to improve its convergence speed. A PWM algorithm enabling permuted switching of the PV sources is applied. The method enables this PV system to achieve the maximum power generation for any number of PV and converter modules. Simulation studies of the proposed MPPT scheme are performed on a system having two chained PV buck-converter modules and a dc-ac H-bridge connected at its terminals for supplying an AC load. The results show that this type of PV system allows each module to achieve the maximum power generation according its illumination level without affecting the others, and the proposed new control method gives significantly higher power output compared with the conventional P&O and PSO methods

    Rare Earth Element Adsorption to Clay Minerals: Mechanistic Insights and Implications for Recovery from Secondary Sources

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    \ua9 2024 American Chemical Society.The energy transition will have significant mineral demands and there is growing interest in recovering critical metals, including rare earth elements (REE), from secondary sources in aqueous and sedimentary environments. However, the role of clays in REE transport and deposition in these settings remains understudied. This work investigated REE adsorption to the clay minerals illite and kaolinite through pH adsorption experiments and extended X-ray absorption fine structure (EXAFS). Clay type, pH, and ionic strength (IS) affected adsorption, with decreased adsorption under acidic pH and elevated IS. Illite had a higher adsorption capacity than kaolinite; however, >95% adsorption was achieved at pH ∼7.5 regardless of IS or clay. These results were used to develop a surface complexation model with the derived binding constants used to predict REE speciation in the presence of competing sorbents. This demonstrated that clays become increasingly important as pH increases, and EXAFS modeling showed that REE can exist as both inner- and outer-sphere complexes. Together, this indicated that clays can be an important control on the transport and enrichment of REE in sedimentary systems. These findings can be applied to identify settings to target for resource extraction or to predict REE transport and fate as a contaminant

    Can Community Gardens with Workshops Increase Gardening Behavior? A Navajo Wellness Collaboration

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    This paper seeks to evaluate the potential efficacy of a community gardening intervention on the Navajo Nation to increase gardening and healthy eating behaviors, which are potentially important in preventing obesity and related health conditions. Rates of obesity are high among American Indians, including those living on Navajo Nation land. Eating fresh fruits and vegetables is part of healthy eating. However, availability and access to fresh fruits and vegetables are severely limited on the Navajo Nation, due to distance and cost. One way to increase both availability and consumption of fresh fruits and vegetables is through community gardening, yet many on the Navajo Nation have limited knowledge and capacity to garden. Methods: We used a quasi-experimental pre-post study design to estimate the effect of a community gardening intervention. Primary outcomes of interest were gardening frequency and fruit and vegetable consumption. Community gardens were constructed and planted in two communities on the Navajo Nation. In addition, a series of gardening workshops were held in each community. Community members were recruited to complete surveys at time points before and after the workshops. The time between baseline and follow-up was approximately one year. Results: We surveyed 169 participants at one time point at least, across both communities, and 25 of these participated in the gardening workshops. Within the 169, there was a cohort of 32 participants completing both baseline and follow-up surveys. For this cohort, interest in gardening increased from 78% to 97% (p=0.014), but none of the changes in gardening self-efficacy, knowledge or gardening frequency reached statistical significance. There were no measurable changes in reported fruit and vegetable consumption, self-efficacy or knowledge. Overall, the reported financial barriers to gardening increased from baseline to follow-up from 4.6 to 5.5 (p=0.035). Altogether 52 participants completed follow-up. In this group, those who attended at least one workshop gardened more frequently at follow-up than those who did not attend any workshops (21 times per month compared to 10 times per month (p=0.07). Conclusion: Despite enthusiasm for the community garden in both the communities studied and the increased interest in gardening, workshop attendance and participant retention in the study were low. These factors limited our ability to evaluate the potential efficacy of the intervention on gardening and healthy eating behaviors. Nonetheless, we found some evidence that participating in gardening workshops may lead to increased gardening frequency. Future studies should augment the intervention to include explicit efforts to reduce barriers to long term engagement and extend intervention reach

    Growth characteristics in individuals with osteogenesis imperfecta in North America: results from a multicenter study.

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    PurposeOsteogenesis imperfecta (OI) predisposes people to recurrent fractures, bone deformities, and short stature. There is a lack of large-scale systematic studies that have investigated growth parameters in OI.MethodsUsing data from the Linked Clinical Research Centers, we compared height, growth velocity, weight, and body mass index (BMI) in 552 individuals with OI. Height, weight, and BMI were plotted on Centers for Disease Control and Prevention normative curves.ResultsIn children, the median z-scores for height in OI types I, III, and IV were -0.66, -6.91, and -2.79, respectively. Growth velocity was diminished in OI types III and IV. The median z-score for weight in children with OI type III was -4.55. The median z-scores for BMI in children with OI types I, III, and IV were 0.10, 0.91, and 0.67, respectively. Generalized linear model analyses demonstrated that the height z-score was positively correlated with the severity of the OI subtype (P < 0.001), age, bisphosphonate use, and rodding (P < 0.05).ConclusionFrom the largest cohort of individuals with OI, we provide median values for height, weight, and BMI z-scores that can aid the evaluation of overall growth in the clinic setting. This study is an important first step in the generation of OI-specific growth curves

    MCMC for Bayesian uncertainty quantification from time-series data

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    In computational neuroscience, Neural Population Models (NPMs) are mechanistic models that describe brain physiology in a range of different states. Within computational neuroscience there is growing interest in the inverse problem of inferring NPM parameters from recordings such as the EEG (Electroencephalogram). Uncertainty quantification is essential in this application area in order to infer the mechanistic effect of interventions such as anaesthesia. This paper presents Open image in new window software for Bayesian uncertainty quantification in the parameters of NPMs from approximately stationary data using Markov Chain Monte Carlo (MCMC). Modern MCMC methods require first order (and in some cases higher order) derivatives of the posterior density. The software presented offers two distinct methods of evaluating derivatives: finite differences and exact derivatives obtained through Algorithmic Differentiation (AD). For AD, two different implementations are used: the open source Stan Math Library and the commercially licenced Open image in new window tool distributed by NAG (Numerical Algorithms Group). The use of derivative information in MCMC sampling is demonstrated through a simple example, the noise-driven harmonic oscillator. And different methods for computing derivatives are compared. The software is written in a modular object-oriented way such that it can be extended to derivative based MCMC for other scientific domains

    Structure of the hDmc1-ssDNA filament reveals the principles of its architecture

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    In eukaryotes, meiotic recombination is a major source of genetic diversity, but its defects in humans lead to abnormalities such as Down's, Klinefelter's and other syndromes. Human Dmc1 (hDmc1), a RecA/Rad51 homologue, is a recombinase that plays a crucial role in faithful chromosome segregation during meiosis. The initial step of homologous recombination occurs when hDmc1 forms a filament on single-stranded (ss) DNA. However the structure of this presynaptic complex filament for hDmc1 remains unknown. To compare hDmc1-ssDNA complexes to those known for the RecA/Rad51 family we have obtained electron microscopy (EM) structures of hDmc1-ssDNA nucleoprotein filaments using single particle approach. The EM maps were analysed by docking crystal structures of Dmc1, Rad51, RadA, RecA and DNA. To fully characterise hDmc1-DNA complexes we have analysed their organisation in the presence of Ca2+, Mg2+, ATP, AMP-PNP, ssDNA and dsDNA. The 3D EM structures of the hDmc1-ssDNA filaments allowed us to elucidate the principles of their internal architecture. Similar to the RecA/Rad51 family, hDmc1 forms helical filaments on ssDNA in two states: extended (active) and compressed (inactive). However, in contrast to the RecA/Rad51 family, and the recently reported structure of hDmc1-double stranded (ds) DNA nucleoprotein filaments, the extended (active) state of the hDmc1 filament formed on ssDNA has nine protomers per helical turn, instead of the conventional six, resulting in one protomer covering two nucleotides instead of three. The control reconstruction of the hDmc1-dsDNA filament revealed 6.4 protein subunits per helical turn indicating that the filament organisation varies depending on the DNA templates. Our structural analysis has also revealed that the N-terminal domain of hDmc1 accomplishes its important role in complex formation through domain swapping between adjacent protomers, thus providing a mechanistic basis for coordinated action of hDmc1 protomers during meiotic recombination
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