A Self-Consistent Model For Directional Dependence Of Crack Growth

Fracture growth is considered as the competition between cleavage and dislocation self-organization in elastic-plastic solids. A self-consistent model is proposed to bridge the responses at relevant length scales, an elastic enclave in the immediate vicinity of crack tip, an array of disclination dipoles and macroscopic plastic deformation. The directional dependence of crack growth is studied. In the continuum limit, the flow stress is expressed by a spatial coupling in terms of a second-order gradient of the rotation strength of disclination dipoles. An estimate of the core size and the crack-tip shielding ratio is given by identification of the macroscopic plastic fields, the elastic field and the constitutive flow stress from the micromechanics consideration, on the boundary of elastic core. Strong dependence of apparent fracture toughness on the intrinsic surface energy and the ductile-to-brittle transition are examined

Revision of the Synechococcales (Cyanobacteria) through recognition of four families including Oculatellaceae fam. nov. and Trichocoleaceae fam. nov. and six new genera containing 14 species

A total of 48 strains of thin, filamentous cyanobacteria in Synechococcales were studied by sequencing 16S rRNA and rpo C1 sequence fragments. We also carefully characterized a subset of these by morphology. Phylogenetic analysis of the 16S rRNA gene data using Bayesian inference of a large Synechococcales alignment (345 OTU’s) was in agreement with the phylogeny based on the rpo C1 gene for 59 OTU’s. Both indicated that the large family-level grouping formerly classified as the Leptolyngbyaceae could be further divided into four family-level clades. Two of these family-level clades have been recognized previously as Leptolyngbyaceae and Prochlorotrichaceae. Oculatellaceae fam. nov. and Trichocoleaceae fam. nov. are proposed for the other two families. The Oculatellaceae was studied in greater detail, and six new genera containing 14 species were characterized and named. These new taxa are: Pegethrix botrychoides , P. olivacea, P. convoluta , P. indistincta , Drouetiella lurida , D. hepatica , D. fasciculata , Cartusia fontana , Tildeniella torsiva , T. nuda , Komarkovaea angustata , Kaiparowitsia implicata , Timaviella obliquedivisa , and T. radians

Molecular characterization of Geitleria appalachiana sp. nov. (Nostocales, Cyanobacteria) and formation of Geitleriaceae fam. nov.

Geitleria was described from a limestone cave in Israel, and subsequently reported from caves of France, Romania, Spain, Florida, Costa Rica, and Cook Islands. It is morphologically unusual in that it has true branching, but no heterocytes. A morphologically distinct species of Geitleria was recently collected from a limestone cave in Great Smoky Mountains National Park, Tennessee, and is herein described as G. appalachiana sp. nov. Sequence data for 16S rRNA and rpoC1 loci for the species were obtained from field material using single filament PCR. Phylogenetic evidence indicates that Geitleria does not belong to any family in the Nostocales containing true–branching genera, i.e. Hapalosiphonaceae, Chlorogloeopsidaceae, and Symphyonemataceae, and consequently Geitleriaceae fam. nov. is established to contain this unique genus

A formal analysis of Correspondence Theory

This paper provides a computational analysis of the complexity of GEN and Correspondence Theory in terms of the nature of the logic involved in their formulation. The first result of this analysis shows that the GEN function is not definable in Monadic Second Order (MSO) logic. Second, we show that the set of input-output Correspondence-theoretic candidates from a given underlying representation is definable in First Order (FO) logic, which is less complex than MSO-logic. Third, we present some case studies where the correct input-output Correspondence-theoretic candidate from a given underlying representation can be accomplished with FO-definable, language-specific, inviolable constraints without recourse to optimization

Implications of bleeding in acute coronary syndrome and percutaneous coronary intervention

The advent of potent antiplatelet and antithrombotic agents over the past decade has resulted in significant improvement in reducing ischemic events in acute coronary syndrome (ACS). However, the use of antiplatelet and antithrombotic combination therapy, often in the settings of percutaneous coronary intervention (PCI), has led to an increase in the risk of bleeding. In patients with non-ST elevation myocardial infarction treated with antithrombotic agents, bleeding has been reported to occur in 0.4%–10% of patients, whereas in patients undergoing PCI, periprocedural bleeding occurs in 2.2%–14% of cases. Until recently, bleeding was considered an intrinsic risk of antithrombotic therapy, and efforts to reduce bleeding have received little attention. There have been increasing data demonstrating that bleeding is associated with adverse outcomes, including myocardial infarction, stroke, and death. Therefore, it is imperative to optimize patient outcomes by adopting pharmacological and nonpharmacological strategies to minimize bleeding while maximizing treatment efficacy. In this paper, we present a review of the bleeding classifications used in large-scale clinical trials in patients with ACS and those undergoing PCI treated with antiplatelets and antithrombotic agents, adverse outcomes, particularly mortality associated with bleeding complications, and suggested predictive risk factors. Potential mechanisms of the association between bleeding and mortality and strategies to reduce bleeding complications are also discussed

Measuring deliberate reflection in residents: validation and psychometric properties of a measurement tool

PURPOSE: Reflective capacity is the ability to understand critical analysis of knowledge and experience to achieve deeper meaning. In medicine, there is little provision for post-graduate medical education to teach deliberate reflection. The feasibility, scoring characteristics, reliability, validation, and adaptability of a modified previously validated instrument was examined for its usefulness assessing reflective capacity in residents as a step toward developing interventions for improvement. METHODS: Third-year residents and fellows from four anesthesia training programs were administered a slightly modified version of the Reflection Evaluation for Learners\u27 Enhanced Competencies Tool (REFLECT) in a prospective, observational study at the end of the 2019 academic year. Six written vignettes of imperfect anesthesia situations were created. Subjects recorded their perspectives on two randomly assigned vignettes. Responses were scored using a 5-element rubric; average scores were analyzed for psychometric properties. An independent self-report assessment method, the Cognitive Behavior Survey: Residency Level (rCBS) was used to examine construct validity. Internal consistency (ICR, Cronbach\u27s alpha) and interrater reliability (weighted kappa) were examined. Pearson correlations were used between the two measures of reflective capacity. RESULTS: 46/136 invited subjects completed 2/6 randomly assigned vignettes. Interrater agreement was high (k = 0.85). The overall average REFLECT score was 1.8 (1-4 scale) with good distribution across the range of scores. ICR for both the REFLECT score (mean 1.8, sd 0.5; α = 0.92) and the reflection scale of the rCBS (mean 4.5, sd 1.1; α = 0.94) were excellent. There was a significant correlation between REFLECT score and the rCBS reflection scale (r = .44, p \u3c 0.01). CONCLUSIONS: This study demonstrates feasibility, reliability, and sufficiently robust psychometric properties of a modified REFLECT rubric to assess graduate medical trainees\u27 reflective capacity and established construct/convergent validity to an independent measure. The instrument has the potential to assess the effectiveness of interventions intended to improve reflective capacity

Antithrombotic strategies in patients undergoing percutaneous coronary intervention for acute coronary syndrome

In patients undergoing percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS), both periprocedural acute myocardial infarction and bleeding complications have been shown to be associated with early and late mortality. Current standard antithrombotic therapy after coronary stent implantation consists of lifelong aspirin and clopidogrel for a variable period depending in part on the stent type. Despite its well-established efficacy in reducing cardiac-related death, myocardial infarction, and stroke, dual antiplatelet therapy with aspirin and clopidogrel is not without shortcomings. While clopidogrel may be of little beneficial effect if administered immediately prior to PCI and may even increase major bleeding risk if coronary artery bypass grafting is anticipated, early discontinuation of the drug may result in insufficient antiplatelet coverage with thrombotic complications. Optimal and rapid inhibition of platelet activity to suppress ischemic and thrombotic events while minimizing bleeding complications is an important therapeutic goal in the management of patients undergoing percutaneous coronary intervention. In this article we present an overview of the literature on clinical trials evaluating the different aspects of antithrombotic therapy in patients undergoing PCI and discuss the emerging role of these agents in the contemporary era of early invasive coronary intervention. Clinical trial acronyms and their full names are provided in Table 1

2017 update on pain management in patients with chronic kidney disease

The prevalence of pain has been reported to be \u3e60–70% among patients with advanced and end-stage kidney disease. Although the underlying etiologies of pain may vary, pain per se has been linked to lower quality of life and depression. The latter is of great concern given its known association with reduced survival among patients with end-stage kidney disease.We herein discuss and update the management of pain in patients with chronic kidney disease with and without requirement for renal replacement therapy with the focus on optimizing pain control while minimizing therapy-induced complications

Pregnancy cohorts and biobanking in sub-Saharan Africa: a systematic review

Background: Technological advances and high throughput biological assays can facilitate discovery science in biobanks from population cohorts, including pregnant women. Biological pathways associated with health outcomes differ depending on geography, and high-income country data may not generalise to low-resource settings. We conducted a systematic review to identify prospective pregnancy cohorts in sub-Saharan Africa (SSA) that include biobanked samples with potential to enhance discovery science opportunity. Methods: Inclusion criteria were prospective data collection during pregnancy, with associated biobanking in SSA. Data sources included: scientific databases (with comprehensive search terms), grey literature, hand searching applicable reference lists and expert input. Results were screened in a three-stage process based on title, abstract and full text by two independent reviewers. The review is registered on PROSPERO (CRD42019147483). Results: Fourteen SSA studies met the inclusion criteria from database searches (n=8), reference list searches (n=2) and expert input (n=4). Three studies have ongoing data collection. The most represented countries were South Africa and Mozambique (Southern Africa) (n=3), Benin (Western Africa) (n=4) and Tanzania (Eastern Africa) (n=4); including an estimated 31 763 women. Samples commonly collected were blood, cord blood and placenta. Seven studies collected neonatal samples. Common clinical outcomes included maternal and perinatal mortality, malaria and preterm birth. Conclusions: Increasingly numerous pregnancy cohorts in SSA that include biobanking are generating a uniquely valuable resource for collaborative discovery science, and improved understanding of the high regional risks of maternal, fetal and neonatal morbidity and mortality. Future studies should align protocols and consider their added value and distinct contributions