An extended finite element method with smooth nodal stress

The enrichment formulation of double-interpolation finite element method (DFEM) is developed in this paper. DFEM is first proposed by Zheng \emph{et al} (2011) and it requires two stages of interpolation to construct the trial function. The first stage of interpolation is the same as the standard finite element interpolation. Then the interpolation is reproduced by an additional procedure using the nodal values and nodal gradients which are derived from the first stage as interpolants. The re-constructed trial functions are now able to produce continuous nodal gradients, smooth nodal stress without post-processing and higher order basis without increasing the total degrees of freedom. Several benchmark numerical examples are performed to investigate accuracy and efficiency of DFEM and enriched DFEM. When compared with standard FEM, super-convergence rate and better accuracy are obtained by DFEM. For the numerical simulation of crack propagation, better accuracy is obtained in the evaluation of displacement norm, energy norm and the stress intensity factor

Application of smooth particle hydrodynamics method for modelling blood flow with thrombus formation

Thrombosis plays a crucial role in atherosclerosis or in haemostasis when a blood vessel is injured. This article focuses on using a meshless particle-based Lagrangian numerical technique, the smoothed particles hydrodynamic (SPH) method, to study the flow behaviour of blood and to explore the flow parameters that induce formation of a thrombus in a blood vessel. Due to its simplicity and effectiveness, the SPH method is employed here to simulate the process of thrombogenesis and to study the effect of various blood flow parameters. In the present SPH simulation, blood is modelled by two sets of particles that have the characteristics of plasma and of platelet, respectively. To simulate coagulation of platelets which leads to a thrombus, the so-called adhesion and aggregation mechanisms of the platelets during this process are modelled by an inter-particle force model. The transport of platelets in the flowing blood, platelet adhesion and aggregation processes are coupled with viscous blood flow for various low Reynolds number scenarios. The numerical results are compared with the experimental observations and a good agreement is found between the simulated and experimental results

Simulation of the flow of self-compacting concrete in the V-funnel by SPH

The flow of self-compacting concrete (SCC) mixes through a V-funnel is simulated from the moment the gate is opened until the time when the light was first seen in the bottom opening through observation from the top (discharge time, tv-funnel). For this simulation, the three-dimensional mesh-less smooth particle hydrodynamics (SPH) computational approach is chosen in which the SCC mix is treated as a non-Newtonian Bingham-type fluid. The numerical simulation results for the discharge time agree very favourably with those recorded in the laboratory on a range of normal strength SCC mixes with cube compressive strengths from 30 to 80 MPa with a maximum size crushed coarse aggregate of 20 mm. In contrast, the two-dimensional simulation of the V-funnel test is found to underestimate significantly the discharge time. The statistics of the distribution of the coarse aggregate particles equal to or larger than 8 mm in the mix (this limit is set by the number of particles used in the SPH simulations) shows that the mix remains homogeneous with no settlement of the heavier particles during the flow and after the flow has stopped

The British HIV Association national clinical audit 2021: Management of HIV and hepatitis C coinfection

Objectives: We aimed to describe clinical policies for the management of people with HIV/hepatitis C virus (HCV) coinfection and to audit routine monitoring and assessment of people with HIV/HCV coinfection attending UK HIV care. Methods: This was a clinic survey and retrospective case-note review. HIV clinics in the UK participated in the audit from May to July 2021 by completing an online questionnaire regarding their clinic's policies for the management of people with HIV/HCV coinfection, and by contributing to a case-note review of people living with HIV with detectable HCV RNA who were under the care of their service. Results: Ninety-five clinics participated in the clinic survey; of these, 15 (15.8%) were regional specialist centres, 19 (20.0%) were HIV services with their own coinfection clinics, 40 (42.1%) were HIV services that referred coinfected individuals to a local hepatology service and 20 (21.1%) were HIV services that referred to a regional specialist centre. Eighty-one clinics provided full caseload estimates; of the approximately 3951 people with a history of HIV/HCV coinfection accessing their clinics, only 4.9% were believed to have detectable HCV RNA, 3.15% of whom were already receiving or approved for direct-acting antiviral (DAA) treatment. In total, 29 (30.5%) of the clinics reported an impact of COVID-19 on coinfection care, including delays or reductions in the frequency of services, monitoring, treatment initiation and appointments, and changes to the way that treatment was dispensed. Case-note reviews were provided for 283 people with detectable HCV RNA from 74 clinics (median age 42 years, 74.6% male, 56.2% HCV genotype 1, 22.3% HCV genotype 3). Overall, 56% had not received treatment for HCV, primarily due to lack of engagement in care (54.7%) and/or being uncontactable (16.4%). Conclusions: Our findings show that the small number of people with HIV with detectable HCV RNA in the UK should mean that it is possible to achieve HCV micro-elimination. However, more work is needed to improve engagement in care for those who are untreated for HCV

An efficient SPH methodology for modelling mechanical characteristics of particulate composites

Particulate composites are one of the widely used materials in producing numerous state-of-the-art components in biomedical, automobile, aerospace including defence technology. Variety of modelling techniques have been adopted in the past to model mechanical behaviour of particulate composites. Due to their favourable properties, particle-based methods provide a convenient platform to model failure or fracture of these composites. Smooth particle hydrodynamics (SPH) is one of such methods which demonstrate excellent potential for modelling failure or fracture of particulate composites in a Lagrangian setting. One of the major challenges in using SPH method for modelling composite materials depends on accurate and efficient way to treat interface and boundary conditions. In this paper, a master-slave method based multi-freedom constraints is proposed to impose essential boundary conditions and interfacial displacement constraints in modelling mechanical behaviour of composite materials using SPH method. The proposed methodology enforces the above constraints more accurately and requires only smaller condition number for system stiffness matrix than the procedures based on typical penalty function approach. A minimum cut-off value-based error criteria is employed to improve the computational efficiency of the proposed methodology. In addition, the proposed method is further enhanced by adopting a modified numerical interpolation scheme along the boundary to increase the accuracy and computational efficiency. The numerical examples demonstrate that the proposed master-slave approach yields better accuracy in enforcing displacement constraints and requires approximately the same computational time as that of penalty method

Severe ocular Mpox in person living with advanced HIV treated with extended course of tecovirimat.

BACKGROUND: People living with HIV are disproportionately represented among people with severe mpox. Mild and self-limiting conjunctival involvement has been well-documented, and severe ocular complications, including keratitis, corneal scarring, and the associated loss of vision, are increasingly recognized. Tecovirimat is the first-line antiviral therapy for severe mpox, but data around the efficacy of systemic antiviral agents for mpox are limited, particularly in cases of ocular mpox. CASE REPORT: Here, we describe a case of sight-threatening necrotic blepharokeratoconjunctivitis in a person with advanced HIV, requiring an extended course of tecovirimat due to persistent mpox viral shedding for nearly 5 months

3D modelling of the flow of self-compacting concrete with or without steel fibres. Part I: slump flow test

In part I of this two-part paper, a three-dimensional Lagrangian smooth particle hydrodynamics method has been used to model the flow of self-compacting concrete (SCC) with or without short steel fibres in the slump cone test. The constitutive behaviour of this non-Newtonian viscous fluid is described by a Bingham-type model. The 3D simulation of SCC without fibres is focused on the distribution of large aggregates (larger than or equal to 8 mm) during the flow. The simulation of self-compacting high- and ultra-high- performance concrete containing short steel fibres is focused on the distribution of fibres and their orientation during the flow. The simulation results show that the fibres and/or heavier aggregates do not precipitate but remain homogeneously distributed in the mix throughout the flow

Smoking and drinking in relation to oral potentially malignant disorders in Puerto Rico: a case-control study

<p>Abstract</p> <p>Background</p> <p>Oral cancer incidence is high on the Island of Puerto Rico (PR), particularly among males. As part of a larger study conducted in PR, we evaluated smoking and drinking as risk factors for oral potentially malignant disorders (OPMDs).</p> <p>Methods</p> <p>Persons diagnosed with either an OPMD (n = 86) [oral epithelial dysplasia (OED), oral hyperkeratosis/epithelial hyperplasia without OED] or a benign oral tissue condition (n = 155) were identified through PR pathology laboratories. Subjects were interviewed using a standardized, structured questionnaire that obtained information, including detailed histories of smoking and drinking. Odds ratios (ORs) for smoking and drinking in relation to having an OPMD, relative to persons with a benign oral tissue condition, were obtained using logistic regression and adjusted for age, gender, education, fruit/vegetable intake and smoking or drinking.</p> <p>Results</p> <p>For persons with an OPMD and relative to individuals with a benign oral tissue condition, the adjusted OR for current smoking was 4.32 (95% CI: 1.99-9.38), while for former smokers, the OR_adjwas 1.47 (95% CI: 0.67-3.21), each OR_adjrelative to never smokers. With regard to drinking, no adjusted ORs approached statistical significance, and few point estimates exceeded 1.0, whether consumption was defined in terms of ever, current, level (drinks/week), or beverage type.</p> <p>Conclusions</p> <p>In this study, conducted in Puerto Rico, current smoking was a substantial risk factor for OPMDs while former smokers had a considerably reduced risk compared to current smokers. There was little evidence suggesting that alcohol consumption was positively associated with OPMD risk.</p