4,168 research outputs found
Assessing the influence of the rhizosphere on soil hydraulic properties using X-ray Computed Tomography and numerical modelling
Understanding the dynamics of water distribution in soil is crucial for enhancing our knowledge of managing soil and water resources. The application of X-ray Computed Tomography (CT) to the plant and soil sciences is now well established. However, few studies have utilised the technique for visualising water in soil pore spaces. Here we utilise this method to visualise the water in soil in situ and in three-dimensions at successive reductive matric potentials in bulk and rhizosphere soil. The measurements are combined with numerical modelling to determine the unsaturated hydraulic conductivity, providing a complete picture of the hydraulic properties of the soil. The technique was performed on soil cores that were sampled adjacent to established roots (rhizosphere soil) and from soil that had not been influenced by roots (bulk soil). A water release curve was obtained for the different soil types using measurements of their pore geometries derived from CT imaging and verified using conventional methods e.g. pressure plates. The water, soil and air phases from the images were segmented and quantified using image analysis. The water release characteristics obtained for the contrasting soils showed clear differences in hydraulic properties between rhizosphere and bulk soil, especially in clay soil. The data suggests that soils influenced by roots (rhizosphere soil) are less porous due to increased aggregation when compared to bulk soil. The information and insights obtained on the hydraulic properties of rhizosphere and bulk soil will enhance our understanding of rhizosphere biophysics and improve current water uptake models
The Influence of Sport-Related Concussion on Lower Extremity Injury Risk: A Review of Current Return-to-Play Practices and Clinical Implications
International Journal of Exercise Science 13(3): 873-889, 2020. Sport-related concussions (SRCs) are now classified as a major health concern affecting athletes across all sporting levels, with recent evidence suggesting upwards of 3.8 million SRCs occur each year. Multiple injury surveillance datasets have recently determined that athletes post-SRC, compared to non-concussed counterparts, are at greater risk for lower extremity (LE) injury beyond the resolution of traditional SRC assessment batteries. However, it is presently uncertain if common clinical practices (symptom reporting, neuropsychological (NP) examination, and static postural control analysis) can determine athletes at risk for LE injury following an SRC. A comprehensive review of the literature determined that these tools may not reveal subtle cognitive and neuromuscular deficits that lead to subsequent LE injury during dynamic sporting tasks. Current return-to-play (RTP) protocols should consider clarifying the addition of specific objective locomotor analysis, such as gait tasks and sport-specific maneuvers, to determine the risk of LE injury after an athlete has sustained an SRC
Optimal classical-communication-assisted local model of n-qubit Greenberger-Horne-Zeilinger correlations
We present a model, motivated by the criterion of reality put forward by
Einstein, Podolsky, and Rosen and supplemented by classical communication,
which correctly reproduces the quantum-mechanical predictions for measurements
of all products of Pauli operators on an n-qubit GHZ state (or ``cat state'').
The n-2 bits employed by our model are shown to be optimal for the allowed set
of measurements, demonstrating that the required communication overhead scales
linearly with n. We formulate a connection between the generation of the local
values utilized by our model and the stabilizer formalism, which leads us to
conjecture that a generalization of this method will shed light on the content
of the Gottesman-Knill theorem.Comment: New version - expanded and revised to address referee comment
The contribution of multiple barriers to reproduction between edaphically divergent lineages in the Amazonian tree \u3cem\u3eProtium subserratum\u3c/em\u3e (Burseraceae)
Disentangling the strength and importance of barriers to reproduction that arise between diverging lineages is central to our understanding of species origin and maintenance. To date, the vast majority of studies investigating the importance of different barriers to reproduction in plants have focused on short-lived temperate taxa while studies of reproductive isolation in trees and tropical taxa are rare. Here, we systematically examine multiple barriers to reproduction in an Amazonian tree, Protium subserratum (Burseraceae) with diverging lineages of soil specialist ecotypes. Using observational, molecular, distributional, and experimental data, we aimed to quantify the contributions of individual prezygotic and postzygotic barriers including ecogeographic isolation, flowering phenology, pollinator assemblage, pollen adhesion, pollen germination, pollen tube growth, seed development, and hybrid fitness to total reproductive isolation between the ecotypes. We were able to identify five potential barriers to reproduction including ecogeographic isolation, phenological differences, differences in pollinator assemblages, differential pollen adhesion, and low levels of hybrid seed development. We demonstrate that ecogeographic isolation is a strong and that a combination of intrinsic and extrinsic prezygotic and postzygotic barriers may be acting to maintain near complete reproductive isolation between edaphically divergent populations of the tropical tree, P. subserratum
The Preservice Teacher Self-Efficacy for Writing Inventory (PTSWI): A Tool for Measuring Beliefs About Writing
Teachers are often underprepared to teach writing, which can negatively impact the performance and attitudes of their students. In teacher preparation programs, one goal should be to specifically develop future teachers of writing. Focusing on self-efficacy beliefs, increasing preservice teachers’ confidence and preparedness for teaching writing could yield positive impacts on classroom writing instructional practices. Currently, tools to quantitatively measure self-efficacy for writing and writing instruction in preservice teachers are sparse, thus limiting teacher educators’ ability to understand the efficacy of writing instruction. Therefore, the purpose of the present study is to gather evidence of score validity and reliability of a newly developed, theoretically-grounded survey for measuring preservice teacher self-efficacy for writing and writing instruction. The Preservice Teacher Self-Efficacy for Writing Inventory (PTSWI) provides a pragmatic tool designed for use by teacher educators. Results indicate that the PTSWI produces valid and reliable scores that are aligned with current theories from writing research and psychology
High-mobility Group Box 1 Protein Initiates Postoperative Cognitive Decline by Engaging Bone Marrow-derived Macrophages
Background: Aseptic trauma engages the innate immune response to trigger a neuroinflammatory reaction that results in postoperative cognitive decline. The authors sought to determine whether high-mobility group box 1 protein (HMGB1), an ubiquitous nucleosomal protein, initiates this process through activation and trafficking of circulating bone marrow-derived macrophages to the brain. Methods: The effects of HMGB1 on memory (using trace fear conditioning) were tested in adult C57BL/6J male mice; separate cohorts were tested after bone marrow-derived macrophages were depleted by clodrolip. The effect of anti-HMGB1 neutralizing antibody on the inflammatory and behavioral responses to tibial surgery were investigated. Results: A single injection of HMGB1 caused memory decline, as evidenced by a decrease in freezing time (52 11% vs. 39 +/- 5%; n = 16-17); memory decline was prevented when bone marrow-derived macrophages were depleted (39 +/- 5% vs. 50 +/- 9%; n = 17). Disabling HMGB1 with a blocking monoclonal antibody, before surgery, reduced postoperative memory decline (52 +/- 11% vs. 29 +/- 5%; n = 15-16); also, hippocampal expression of monocyte chemotactic protein-1 was prevented by the neutralizing antibody (n = 6). Neither the systemic nor the hippocampal inflammatory responses to surgery occurred in mice pretreated with anti-HMGB1 neutralizing antibody (n = 6). Conclusion: Postoperative neuroinflammation and cognitive decline can be prevented by abrogating the effects of HMGB1. Following the earlier characterization of the resolution of surgery-induced memory decline, the mechanisms of its initiation are now described. Together, these data may be used to preoperatively test the risk to surgical patients for the development of exaggerated and prolonged postoperative memory decline that is reflected in delirium and postoperative cognitive dysfunction, respectively
Preparing pre-service teachers for classroom practice in a virtual world: A pilot study using Second Life
Many pre-service teachers feel under-prepared to teach students with a diverse range of needs and abilities and continue to be concerned about classroom behaviour management when undertaking practicum experiences. In order to address these concerns, teacher educators have explored alternative pedagogical approaches, including computer based simulations and immersion in virtual worlds. This paper reports on the results of a pilot study conducted with eight pre-service teachers who operated avatars in a virtual classroom created within Second Life (SL)™. The pre-service teachers were able to role-play students with a diverse range of behaviours and engage in reflective discussion about their experiences. The results showed that the pre-service teachers appreciated the opportunity to engage in an authentic classroom experience without impacting on "real" students, but that the platform of SL proved limiting in enacting certain aspects of desired teaching pedagogy. The findings of this pilot study are discussed in relation to improving the preparation of pre-service teachers for practicum
Complete Sequences of Organelle Genomes from the Medicinal Plant Rhazya Stricta (Apocynaceae) and Contrasting Patterns of Mitochondrial Genome Evolution Across Asterids
Rhazya stricta is native to arid regions in South Asia and the Middle East and is used extensively in folk medicine to treat a wide range of diseases. In addition to generating genomic resources for this medicinally important plant, analyses of the complete plastid and mitochondrial genomes and a nuclear transcriptome from Rhazya provide insights into inter-compartmental transfers between genomes and the patterns of evolution among eight asterid mitochondrial genomes. Results: The 154,841 bp plastid genome is highly conserved with gene content and order identical to the ancestral organization of angiosperms. The 548,608 bp mitochondrial genome exhibits a number of phenomena including the presence of recombinogenic repeats that generate a multipartite organization, transferred DNA from the plastid and nuclear genomes, and bidirectional DNA transfers between the mitochondrion and the nucleus. The mitochondrial genes sdh3 and rps14 have been transferred to the nucleus and have acquired targeting presequences. In the case of rps14, two copies are present in the nucleus; only one has a mitochondrial targeting presequence and may be functional. Phylogenetic analyses of both nuclear and mitochondrial copies of rps14 across angiosperms suggests Rhazya has experienced a single transfer of this gene to the nucleus, followed by a duplication event. Furthermore, the phylogenetic distribution of gene losses and the high level of sequence divergence in targeting presequences suggest multiple, independent transfers of both sdh3 and rps14 across asterids. Comparative analyses of mitochondrial genomes of eight sequenced asterids indicates a complicated evolutionary history in this large angiosperm clade with considerable diversity in genome organization and size, repeat, gene and intron content, and amount of foreign DNA from the plastid and nuclear genomes. Conclusions: Organelle genomes of Rhazya stricta provide valuable information for improving the understanding of mitochondrial genome evolution among angiosperms. The genomic data have enabled a rigorous examination of the gene transfer events. Rhazya is unique among the eight sequenced asterids in the types of events that have shaped the evolution of its mitochondrial genome. Furthermore, the organelle genomes of R. stricta provide valuable genomic resources for utilizing this important medicinal plant in biotechnology applications.King Abdulaziz UniversityIntegrative Biolog
Improving the measurement of QALYs in dementia: developing patient- and carer-reported health state classification systems using Rasch analysis
Objectives: Cost-utility analysis is increasingly used to inform resource allocation. This requires a means of valuing health states before and after intervention. Although generic measures are typically used to generate values, these do not perform well with people with dementia. We report the development of a health state classification system amenable to valuation for use in studies of dementia, derived from the DEMQOL system, a measure of health-related quality of life in dementia by patient self-report (DEMQOL) and carer proxy-report (DEMQOL-Proxy). Methods: Factor analysis was used to determine the dimensional structure of DEMQOL and DEMQOL-Proxy. Rasch analysis was subsequently used to investigate item performance across factors in terms of item-level ordering, functioning across subgroups, model fit and severity-range coverage. This enabled the selection of one item from each factor for the classification system. A sample of people with a diagnosis of mild/moderate dementia (n=644) and a sample of carers of those with mild/moderate dementia (n=683) were used. Results: Factor analysis found different 5-factor solutions for DEMQOL and DEMQOL-Proxy. Following item reduction and selection using Rasch analysis, a 5-dimension classification for DEMQOL and a 4-dimension classification for DEMQOL-Proxy were developed. Each item contained 4 health state levels. Conclusion: Combining Rasch and classical psychometric analysis is a valid method of selecting items for dementia health state classifications from both the patient and carer perspectives. The next stage is to obtain preference weights so that the measure can be used in the economic evaluation of treatment, care and support arrangements for dementia.quality adjusted life years; health related quality of life; Rasch analysis; preference-based measures of health; health states; dementia
- …