896 research outputs found

    Global Research Alliance N2O chamber methodology guidelines: Recommendations for deployment and accounting for sources of variability

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    Adequately estimating soil nitrous oxide (N2O) emissions using static chambers is challenging due to the high spatial variability and episodic nature of these fluxes. This paper discusses how static chamber N2O experiments can be designed, and protocols implemented, to better account for this variability and reduce the uncertainty of N2O emission estimates. It is part of a series of papers in this special issue, each discussing a particular aspect of N2O chamber methodology. Aspects of experimental design and sampling affected by spatial variability include site selection, and chamber layout, size and areal coverage. Where used, treatment application adds a further level of spatial variability. Time of day, frequency and duration of sampling (both in terms of individual chamber closures and overall experiment duration) affect the temporal variability captured. In addition, we present best practice recommendations for experimental chamber installation and sampling protocols to minimise the introduction of further uncertainty. To obtain the best N2O emission estimates, resources should be allocated to minimise the overall uncertainty in line with experiment objectives. In some cases, this will mean prioritising individual flux measurements and increasing their accuracy and precision by, for example, collecting ā‰„4 headspace samples during each chamber closure. However, where N2O fluxes are exceptionally spatially variable, for example, in heterogeneous agricultural landscapes, such as uneven and woody grazed pastures, using available resources to deploy more chambers with fewer headspace samples per chamber may be beneficial. Similarly, for particularly episodic N2O fluxes, generated for example by irrigation or freeze-thaw cycles, increasing chamber sampling frequency will improve the accuracy and reduce the uncertainty of temporally interpolated N2O fluxe

    The Evolution of Amastin Surface Glycoproteins in Trypanosomatid Parasites

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    Amastin is a transmembrane glycoprotein found on the cell surfaces of trypanosomatid parasites. Encoded by a large, diverse gene family, amastin was initially described from the intracellular, amastigote stage of Trypanosoma cruzi and Leishmania donovani. Genome sequences have subsequently shown that the amastin repertoire is much larger in Leishmania relative to Trypanosoma. However, it is not known when this expansion occurred, whether it is associated with the origins of Leishmania and vertebrate parasitism itself, or prior to this. To examine the timing of amastin diversification, as well as the evolutionary mechanisms regulating gene repertoire and sequence diversity, this study sequenced the genomic regions containing amastin loci from two related insect parasites (Leptomonas seymouri and Crithidia sp.) and estimated a phylogeny for these and other amastin sequences. The phylogeny shows that amastin includes four subfamilies with distinct genomic positions, secondary structures, and evolution, which were already differentiated in the ancestral trypanosomatid. Diversification in Leishmania was initiated from a single ancestral locus on chromosome 34, with rapid derivation of novel loci through transposition and accelerated sequence divergence. This is absent from related organisms showing that diversification occurred after the origin of Leishmania. These results describe a substantial elaboration of amastin repertoire directly associated with the origin of Leishmania, suggesting that some amastin genes evolved novel functions crucial to cell function in leishmanial parasites after the acquisition of a vertebrate host

    Psychotropic medication use pre and post-diagnosis of cluster B personality disorder: a Quebecā€™s health services register cohort

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    Background: Cluster B personality disorders (PDs) are considered some of the most severe mental health conditions. Scarce evidence exists about the real-world utilization of psychotropics for cluster B PD individuals. Objective: We aimed to uncover trends and patterns of psychotropic medication use among individuals diagnosed with cluster B PD in the year before and after their diagnosis and to identify factors associated with medication use in a large cohort of individuals newly diagnosed with cluster B PDs. Methods: We conducted a population-based observational study using Quebec's health services register. We identified Quebec residents aged ā‰„14 years and insured with the provincial drug plan with a first diagnosis of cluster B PD recorded between April 1, 2002, and March 31, 2019. Cluster B PD was defined with ICD-9/10 diagnostic codes. We retrieved all claims for the main psychotropic medication classes: antipsychotics, antidepressants, anxiolytics, mood stabilizers, and attention-deficit/hyperactivity disorder (ADHD) medications. We calculated the proportion of individuals exposed to these medication classes and analyzed trends over the years using robust Poisson regression models, adjusting for potential confounders. We used robust Poisson regression to identify factors associated with medication class use. Results: We identified 87,778 new cases of cluster B PD, with a mean age of 44.5ā€‰years; 57.5% were women. Most frequent psychiatric comorbidities in the five years before cluster B PD diagnosis were depression (50.9%), anxiety (49.7%), and psychotic disorders (37.5%). Most individuals (71.0%) received at least one psychotropic during the year before cluster B PD diagnosis, and 78.5% received at least one of these medications in the subsequent year. The proportion of users increased after the diagnosis for antidepressants (51.6-54.7%), antipsychotics (35.9-45.2%), mood stabilizers (14.8-17.0%), and ADHD medications (5.1-5.9%), and remained relatively stable for anxiolytics (41.4-41.7%). Trends over time showed statistically significant increased use of antipsychotics and ADHD medications, decreased use of anxiolytics and mood stabilizers, and a stable use of antidepressants. Conclusion: Psychotropic medication use is highly prevalent among cluster B PD individuals. We observed an increase in medication use in the months following the diagnosis, particularly for antipsychotics, antidepressants, and mood stabilizers

    High fidelity numerical fracture mechanics assisted by RBF mesh morphing

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    The study and design of cyclically loaded structures cannot neglect the evaluation of their fatigue behavior. Today numerical prediction tools allow adopting, in various industrial fields, refined and consolidated procedures for the assessment of cracked parts through analyses based on fracture mechanics. An high level of detail can be obtained through the use of well consolidated FEM methods, allowing an accurate and reliable calculation of the flaw Stress Intensity Factor (SIF) and its resulting prediction in terms of crack propagation. A challenging step for this computational workflow remains, however, the generation and update of the computational grid during crack evolution. It is in this context that radial basis functions (RBF) mesh morphing is emerging as a viable solution to replace the complex and time-consuming remeshing operation. The flaw front is updated, according to its propagation, by automatically deforming the numerical grid obtaining an evolutionary workflow suitable to be used for industrially-sized numerical meshes (many millions of nodes). A review of applications, obtained by exploiting FEA (Ansys Mechanical) and mesh morphing (RBF Morph) state of-the-art tools, is presented in this work. At first the proposed workflow is applied on a circular notched bar with a defect controlled by a two-parameters evolution. The same approach is then refined and demonstrated for a Multi Degree of Freedom (MDoF) case on the same geometry and on the vacuum vessel port stub from the fusion nuclear reactor Iter
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