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To date, the Smoothed Particle Hydrodynamics (SPH) method has been successfully applied to reproduce the hydrodynamics behind three-dimensional flow-structure interactions. However, as soon as the effect of flow resistance becomes significant, the results obtained are not consistent with observations. This is the case for open channel flows (OCF), in which the water surface is largely influenced by the boundary friction. The roughness generated by the current boundary condition methodologies is solely numerical and cannot be associated to physical values of friction. In light of this challenge, the authors present a novel formulation for the friction boundary condition. The new implementation includes an additional shear stress at the boundaries to reproduce roughness effects, allowing for the adequate three-dimensional simulation of open channel flows using the SPH method. Finally, in order to reduce the high computational cost, typical of the Lagrangian models, without interfering in the representativeness of the SPH simulations, a criterion to define the adequate fluid particle size is proposed. [ABSTRACT FROM AUTHOR]

Abstract Background Swarming is a multicellular phenomenom characterized by the coordinated and rapid movement of bacteria across semisolid surfaces. In Sinorhizobium meliloti this type of motility has been described in a fadD mutant. To gain insights into the mechanisms underlying the process of swarming in rhizobia, we compared the transcriptome of a S. meliloti fadD mutant grown under swarming inducing conditions (semisolid medium) to those of cells grown under non-swarming conditions (broth and solid medium). Results More than a thousand genes were identified as differentially expressed in response to growth on agar surfaces including genes for several metabolic activities, iron uptake, chemotaxis, motility and stress-related genes. Under swarming-specific conditions, the most remarkable response was the up-regulation of iron-related genes. We demonstrate that the pSymA plasmid and specifically genes required for the biosynthesis of the siderophore rhizobactin 1021 are essential for swarming of a S. meliloti wild-type strain but not in a fadD mutant. Moreover, high iron conditions inhibit swarming of the wild-type strain but not in mutants lacking either the iron limitation response regulator RirA or FadD. Conclusions The present work represents the first transcriptomic study of rhizobium growth on surfaces including swarming inducing conditions. The results have revealed major changes in the physiology of S. meliloti cells grown on a surface relative to liquid cultures. Moreover, analysis of genes responding to swarming inducing conditions led to the demonstration that iron and genes involved in rhizobactin 1021 synthesis play a role in the surface motility shown by S. meliloti which can be circumvented in a fadD mutant. This work opens a way to the identification of new traits and regulatory networks involved in swarming by rhizobia.

Introduction and Importance: Neonatal appendicitis is a rare condition with high morbidity and mortality due to its late diagnosis in favor of more common pathologies. There are few reported cases of neonatal appendicitis and even fewer of antenatal appendicitis., Case Presentation: We report a neonate presenting with abdominal distention and gastric emesis in the setting of a suspected congenital abdominal mass, later diagnosed with neonatal appendicitis requiring intestinal resection and anastomosis., Clinical Discussion: Neonatal appendicitis presents with nonspecific symptoms and may often be mistaken for enterocolitis or intestinal malrotation. Additional imaging, including abdominal radiographs, ultrasound, or computed tomography, may facilitate diagnosis., Conclusion: Neonatal appendicitis is a rare entity with a challenging diagnosis due to the lack of specific signs. In the current case, the patient was referred to our institution with an antenatal ultrasound showing a right flank mass which resulted in abscess formation and perforated appendicitis., Competing Interests: Declaration of competing interest The authors declare that they have no competing economic interests or known personal relationships that could have influenced the work reported in this document., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The identification of biomarkers has become increasingly important in our fundamental understanding of the molecular basis for disease and subsequently in the advancement of modern medicine. Biomarkers have been identified in a plethora of normal and pathologic conditions and are most often found in blood, tissue, or synovial fluid. Orthopaedic research has more recently focused on biomarkers of cartilage and joint diseases, with an emphasis on understanding the molecular underpinnings of their pathophysiology. This article focuses on the biomarkers identified to date in several select knee pathologies and how further research can contribute to new diagnostic tools and targeted therapeutics.