Structural softening, mesh dependence, and regularisation in non‐associated plastic flow

A severe dependence of numerical simulations on the mesh density is usually attributed to the presence of strain softening in the constitutive relation. However, other material instabilities, like non‐associated plastic flow, can also cause mesh sensitivity. Indeed, loss of ellipticity in quasi‐static analyses is the fundamental cause of the observed mesh dependence. It has been known since long that non‐associated plastic flow can cause loss of ellipticity, but the consequence for mesh sensitivity, and subsequently, for the difficulty of the equilibrium‐finding iterative procedure to converge have remained largely unnoticed. We first demonstrate at the hand of a biaxial test structural softening and a marked mesh dependence for an ideally plastic material equipped with a non‐associated flow rule. The phenomena are then analysed in depth using an infinitely long shear layer. Finally, it is shown that the mesh effect disappears when the standard continuum model is replaced by a Cosserat continuum, a well‐known regularisation method for strain‐softening constitutive relations

Convergence in non‐associated plasticity and fracture propagation for standard, rate‐dependent, and Cosserat continua

The use of pressure‐dependent plasticity models with a non‐associated flow rule causes a loss of the well‐posedness for sufficiently low hardening rates. Apart from a mesh dependence, this can result in poor convergence, or even divergence of the iterative procedure employed to find an equilibrium configuration. This can be aggravated when other nonlinear, dissipative mechanisms are introduced, for instance the propagation of cracks. This is demonstrated rigorously, as well as the regularizing effect of adding viscosity or employing a Cosserat continuum. In both cases the regularization is independent of the value of the internal length scale for a fairly wide range of parameters. The spatial discretization has been done using T‐splines, and the fracture is modeled using interface elements and propagated using mesh line insertions. The time integration has been done by an implicit Newmark scheme. The use of proper regularization techniques makes an implicit scheme feasible, resulting in a reduction in the number of time steps by an order of magnitude

Cash-based interventions to enhance dignity in persistent humanitarian refugee crises: a system dynamics approach

Cash-based interventions (CBIs) as one form of aid have recently received substantial interest from humanitarian organizations in persistent humanitarian crises. This article proposes a system dynamics (SD) approach to study the CBIs' impact factors on all aspects of the beneficiaries' dignity in longstanding refugee crises, such as the case of Syrian refugees in Turkey. Reviewing the humanitarian management literature,we first develop a set of holistic causal loops to better understand the building boxes of refugees’ dignity and their interactions. Then, an SD model is proposed and calibrated by field data from humanitarian organizations. The result of CBI amount sensitivity and payment time periods shows that CBIs are significantly more effective in diminishing child labor rates and to improve in health and accommodation service reception by the refugees in short terms, but to be as much effective in longer terms, humanitarian organizations must be more directly contribute to service capacity-building activities that are strategies by the hosting governments and supported by the international bodies, such as EU and UN.Otherwise, long-term or enhanced CBI supports can only lead to accelerated service capacity saturation and thus put extra pressure on already strained services and cause tensions between hosting and refugee communities

Screening and diagnostic assessment of neurodevelopmental disorders in a male prison

Purpose The purpose of this paper is to identify neurodevelopmental disorders and difficulties (NDD) in a male prison. The study used standardised tools to carry out screening and diagnostic assessment of the attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and intellectual disability (ID). Design/methodology/approach The ADHD self-report scale, 20-item autism quotient and the Learning Disability Screening Questionnaire were used to screen 240 male prisoners. Prisoners who screened positive on one or more of these scales or self-reported a diagnosis of ADHD, ASD or ID were further assessed using the diagnostic interview for ADHD in adults, adapted Autism Diagnostic Observation Schedule and the Quick Test. Findings Of the 87 prisoners who screened positive for NDD and were further assessed, 70 met the study’s diagnostic criteria for ADHD, ASD or ID. Most of those with NDD (51 per cent) had previously gone unrecognised and a high proportion (51 per cent) were identified through staff- or self-referral to the study. Originality/value The study demonstrated that improving awareness and providing access to skilled, standardised assessment within a male prison can result in increased recognition and identification of NDD

Migration of Epithelium During Phenytoin-Dependent Gingival Overgrowth in Mice

A small cavity was made in the mesiopalatal area of the maxillary first molar adjacent to the gingiva. Mice were maintained on 40 mg/kg phenytoin (or on diluent for control) by daily intraperitoneal injections. After 9 weeks, light microscopic observations revealed that in experimental mice, epithelial cells migrated towards the cavity and covered it. In controls, epithelial cell migration towards the cavity did not occur. For scanning electron microscopic (SEM) studies, specimens were fixed in 4% glutaraldehyde in 0.1 M phosphate buffer, pH 7.2, for 2 hours, dehydrated, critical point dried and coated with gold. The surface of the outer gingival epithelium of experimental and of control mice showed a honeycomb arrangement of the microridges suggesting their keratinized nature. Epithelial cells lining the cavity showed well marked macroridges along their borders. Parallel microridges were observed on the upper surface of these cells suggesting that they were non-keratinized. It was concluded that the migrating epithelial cells, that covered the cavity during phenytoin-dependent gingival overgrowth, were of the non-keratinized type

The Association Between Discrimination and Sleep is Exacerbated in Individuals with Comorbid Chronic Health Conditions

Introduction: The consequences of recurrent, stressful daily experiences for sleep health appear intensified in individuals with pre-existing health conditions. Although discrimination has been associated with sleep outcomes, the role of comorbid chronic health conditions (CCHCs), and impact of perceived discrimination, remains unclear. The present study investigated (1) the associations between daily discrimination and sleep and (2) moderating roles of CCHCs and daily life interference and hardship. Methods: The current study utilized archival data from the Midlife in the United States (MIDUS) Study II. Participants, 174 adults (51% female, Mage=57 yrs., SD=11.5 yrs.), completed 7 days of actigraphy, sleep diary, PSQI, and CCHC-reporting measures. Models examined the moderating effects of CCHCs, daily interference, and hardship on the association between discrimination and sleep. Results: Daily discriminatory experiences predicted numerous poor sleep outcomes, exacerbated for persons with higher CCHCs. Higher comorbidity (95% CI=5.40, 68.75) exacerbated the association between discrimination and TSTactigraphy, further strengthened by perceived hardship (95% CI=-3.75, -.40) and interference (95% CI=-3.65, -.30). Number of CCHCs, qualified by perceived hardship (95% CI=.00, .04) and interference (95% CI=.01, .05), predicted diary sleep quality above discrimination. The interaction between CCHCs and hardship predicted global PSQI scores (95% CI=-.91, -.12) beyond discrimination. Conclusion: Daily experiences of discrimination are associated with decreased sleep duration and quality. These associations were stronger for individuals with multiple CCHCs. Exacerbating CCHC effects were perpetuated by perceived interference and hardships, suggesting individual emotion regulation (ER) differences. Future research should attend to sleep-related consequences of differential discrimination-informed ER by persons with CCHCs.https://scholarscompass.vcu.edu/gradposters/1042/thumbnail.jp

A Patient-Centered Methodology That Improves the Accuracy of Prognostic Predictions in Cancer

Peer reviewe

Trade-offs in managing commercial consumer returns for online apparel retail

Purpose: This paper analyses the application of Lean Six Sigma framework for supporting continuous improvement in logistics services. Both the lean philosophy and the Six Sigma methodology have become two of the most important initiatives for continuous improvement in organizations. The combination of both alternatives - Lean Six Sigma (LSS) - brings significant benefits for companies applying this method and its influence in logistics services can be relevant. Design/methodology/approach: A case study on the logistics services of a large consumer electronics company is performed. In this sector, high quality in logistics services is crucial. Using within-case and cross-case analyses, the paper discusses the implementation of LSS in two internal logistics processes. Findings: The paper identifies important implementation aspects when applying LSS to logistics services, such as continuous improvement structure, strategic analysis, cross-functional teams, and process management. Furthermore, the paper discusses the potential in logistics services of the DMAIC approach and tools like VSM, SIPOC and Process Mapping. Practical implications: The paper analyses two logistics processes where LSS has been applied – a payment process and a request-to-ship process. The analysis of both processes offers relevant information about organizational implementation in a logistics services environment, about process improvement and about the use of LSS tools. Originality/value: Firstly, this paper addresses the gap in literature about LSS and logistics’ activities. Furthermore, the case company, with more than 9.000 employees and distributing its products to more than 100 countries, constitutes a valuable source of information to obtain insights in the implications of implementing LSS in logistics services

Mesh bias and shear band inclination in standard and non-standard continua

A severe, spurious dependence of numerical simulations on the mesh size and orientation can be observed in elasto-plastic models with a non-associated flow rule. This is due to the loss of ellipticity and may also cause a divergence in the incremental-iterative solution procedure. This paper first analyses the dependence of the shear band inclination in a biaxial test on the mesh size as well as on the mesh orientation. Next, a Cosserat continuum model, which has been employed successfully for strain-softening plasticity, is proposed to prevent loss of ellipticity. Now, numerical solutions result for shear band formation which are independent of the size and the orientation of the discretisation