A Hybrid Boundary Element Method for Elliptic Problems with Singularities

The singularities that arise in elliptic boundary value problems are treated locally by a singular function boundary integral method. This method extracts the leading singular coefficients from a series expansion that describes the local behavior of the singularity. The method is fitted into the framework of the widely used boundary element method (BEM), forming a hybrid technique, with the BEM computing the solution away from the singularity. Results of the hybrid technique are reported for the Motz problem and compared with the results of the standalone BEM and Galerkin/finite element method (GFEM). The comparison is made in terms of the total flux (i.e. the capacitance in the case of electrostatic problems) on the Dirichlet boundary adjacent to the singularity, which is essentially the integral of the normal derivative of the solution. The hybrid method manages to reduce the error in the computed capacitance by a factor of 10, with respect to the BEM and GFEM

Optimization of Patterned Surfaces for Improved Superhydrophobicity Through Cost-Effective Large-Scale Computations

The growing need for creating surfaces with specific wetting properties, such as superhyrdophobic behavior, asks for novel methods for their efficient design. In this work, a fast computational method for the evaluation of patterned superhyrdophobic surfaces is introduced. The hydrophobicity of a surface is quantified in energy terms through an objective function. The increased computational cost led to the parallelization of the method with the Message Passing Interface (MPI) communication protocol that enables calculations on distributed memory systems allowing for parametric investigations at acceptable time frames. The method is demonstrated for a surface consisting of an array of pillars with inverted conical (frustum) geometry. The parallel speedup achieved allows for low cost parametric investigations on the effect of the fine features (curvature and slopes) of the pillars on the superhydophobicity of the surface and consequently for the optimization of superhyrdophobic surfaces.Comment: 18 pages, 18 figure

Conservation and global distribution of non-canonical antigens in enterotoxigenic Escherichia coli

BACKGROUND: Enterotoxigenic Escherichia coli (ETEC) cause significant diarrheal morbidity and mortality in children of resource-limited regions, warranting development of effective vaccine strategies. Genetic diversity of the ETEC pathovar has impeded development of broadly protective vaccines centered on the classical canonical antigens, the colonization factors and heat-labile toxin. Two non-canonical ETEC antigens, the EtpA adhesin, and the EatA mucinase are immunogenic in humans and protective in animal models. To foster rational vaccine design that complements existing strategies, we examined the distribution and molecular conservation of these antigens in a diverse population of ETEC isolates. METHODS: Geographically diverse ETEC isolates (n = 1159) were interrogated by PCR, immunoblotting, and/or whole genome sequencing (n = 46) to examine antigen conservation. The most divergent proteins were purified and their core functions assessed in vitro. RESULTS: EatA and EtpA or their coding sequences were present in 57.0% and 51.5% of the ETEC isolates overall, respectively; and were globally dispersed without significant regional differences in antigen distribution. These antigens also exhibited \u3e93% amino acid sequence identity with even the most divergent proteins retaining the core adhesin and mucinase activity assigned to the prototype molecules. CONCLUSIONS: EtpA and EatA are well-conserved molecules in the ETEC pathovar, suggesting that they serve important roles in virulence and that they could be exploited for rational vaccine design

Comparing traditional lapidus to new triplane methods for correction of hallux valgus

Hallux valgus deformity, also known as a bunion, involves lateral deviation of the hallux, medial deviation of the first metatarsal, and subluxation of the first metatarsophalangeal joint. The deformity is progressive and is treated surgically when conservative management fails.The prevalence of hallux valgus is estimated to be 23 percent among US adults aged 18 to 65 years old.The Lapidus procedure corrects hallux valgus deformity through fusion of the first tarsometatarsal joint.Current studies estimate that Lapidus arthrodesis has a 10 percent nonunion rate along with a low recurrence rate.Patient satisfaction with the Lapidus procedure has been measured between 78 to 84 percent. Recent developments in the correction of hallux valgus have centered on triplane correction (TPC) utilizing proprietary systems.These systems are effective at obtaining and maintaining correction. However, they are expensive and there is a paucity of unbiased literature comparing it to traditional methods

H3K36 Methylation Regulates Cell Plasticity and Regeneration in the Intestinal Epithelium

Cell plasticity is needed during development and homeostasis to generate diverse cell types from stem and progenitor cells. Following differentiation, plasticity must be restricted in specialized cells to maintain tissue integrity and function. For this reason, specialized cell identity is highly stable under homeostatic conditions; however, cells in some tissues regain plasticity during injury-induced regeneration. While precise gene expression is needed to control these processes, the regulatory mechanisms that restrict or promote cell plasticity are poorly understood. Here, I use the mouse small intestine as a model system to study cell plasticity. I find that H3K36 methylation reinforces expression of cell type-associated genes to maintain specialized cell identity in intestinal epithelial cells. Depleting H3K36 methylation leads to defects in lineage commitment and activates a plastic, regenerative gene expression signature. Correspondingly, I observe rapid and reversible remodeling of H3K36 methylation following injury-induced regeneration. Together, these data suggest a fundamental role for H3K36 methylation in reinforcing specialized lineages and regulating cell plasticity and regeneration.</p

Comparison of modern periacetabular osteotomy for hip dysplasia with total hip arthroplasty for hip osteoarthritis-10-year outcomes are comparable in young adult patients

Young adult patients with symptomatic acetabular dysplasia and marginal secondary osteoarthritis can be faced with the decision to either undergo periacetabular osteotomy (PAO) to relieve symptoms and slow osteoarthritis progression or wait until progression to more advanced disease and undergo total hip arthroplasty (THA). The decision can be difficult, and contemporary literature to guide these decisions is sparse. Therefore, we retrospectively assessed complication rate, survivorship and patient-reported clinical outcomes [modified Harris Hip score (mHHS), UCLA Activity score] in two, consecutive cohorts of patients aged 18-40 years that underwent either PAO for symptomatic acetabular dysplasia (mean age 28.9 years) or THA for advanced secondary osteoarthritis (32.5 years). PAO patients were followed for a mean of 10.5 years (8-19) and THA patients for 11.9 (8-17)  years. Between PAO and THA groups, there were no differences in overall complication rate (4.7% versus 4.7%), non-revision reoperation rate (5.9% versus 2.3%

Is combined surgical dislocation and proximal femoral osteotomy a safe procedure for correction of complex hip deformities?

Complex deformities of the hip requiring intra-articular and proximal femoral correction are challenging with regard to surgical access and complication risk. Combined surgical dislocation and proximal femoral osteotomy (SD/PFO) is a surgical strategy that provides unrestricted access to the joint with the capability for adjunctive PFO. Although providing excellent surgical access, concerns over a potentially high risk of postoperative complications remain, and published information on the safety of this technique remain scarce. In this study, we defined the early complication profile of combined surgery across 48 hips with a variety of complex deformities using a standardized, validated complication grading scheme for hip preservation surgery. Patients were mean age 19.1 years 13-33 years and 60% had previous surgery. At the early mean follow-up of 2.9 years, considerable improvement was seen across all outcome scores. Major complications (Grade III or higher) occurred at a rate of 4.2%