Critical-layer structures and mechanisms in elastoinertial turbulence

Simulations of elastoinertial turbulence (EIT) of a polymer solution at low Reynolds number are shown to display localized polymer stretch fluctuations. These are very similar to structures arising from linear stability (Tollmien-Schlichting (TS) modes) and resolvent analyses: i.e., critical-layer structures localized where the mean fluid velocity equals the wavespeed. Computation of self-sustained nonlinear TS waves reveals that the critical layer exhibits stagnation points that generate sheets of large polymer stretch. These kinematics may be the genesis of similar structures in EIT.Comment: 5 pages, 4 figures; Accepted in Physical Review Letter

Self-sustained elastoinertial Tollmien-Schlichting waves

Direct simulations of two-dimensional plane channel flow of a viscoelastic fluid at Reynolds number Re = 3000 reveal the existence of a family of attractors whose structure closely resembles the linear Tollmien–Schlichting (TS) mode, and in particular exhibits strongly localized stress fluctuations at the critical layer position of the TS mode. At the parameter values chosen, this solution branch is not connected to the nonlinear TS solution branch found for Newtonian flow, and thus represents a solution family that is nonlinearly self-sustained by viscoelasticity. The ratio between stress and velocity fluctuations is in quantitative agreement for the attractor and the linear TS mode, and increases strongly with Weissenberg number, Wi. For the latter, there is a transition in the scaling of this ratio as Wi increases, and the Wi at which the nonlinear solution family comes into existence is just above this transition. Finally, evidence indicates that this branch is connected through an unstable solution branch to two-dimensional elastoinertial turbulence (EIT). These results suggest that, in the parameter range considered here, the bypass transition leading to EIT is mediated by nonlinear amplification and self-sustenance of perturbations that excite the TS mode

A prospective observational study to evaluate the role of restaging transurethral resection of bladder tumour in patients with non-muscle invasive bladder cancer

Background: Transurethral resection of bladder tumour (TURBT) is the primary treatment modality for Non-muscle invasive bladder cancer (NMIBC). Restaging transurethral resection of bladder tumour (RETURBT) is indicated to reduce risk of residual disease and correct staging errors after primary TURBT. The aim of the study is to evaluate the risk of residual tumour and upstaging in NMIBC after TURBT and to investigate the risk factors for the same.Methods: A prospective observational study was carried out over 4 years and 87 patients were included in the study. Patients with NMIBC underwent RETURBT after 2-6 weeks of primary TURBT. The incidence of residual tumour and upstaging in RETUBRT was correlated with various histopathological and morphological parameters in primary TURBT.Results: Out of 87 patients, who underwent RETURBT, residual disease was present in 51 patients (58.6%) and upstaging occurred in 22 patients (25.2%).On univariate analysis, T1 stage (p=0.01), high grade (p=0.01), Carcinoma in situ(CIS) (p=0.01) and multifocality (p=0.05) were predictive for residual disease in RETURBT. High grade (p=0.01), CIS (p=0.01) and absence of detrusor muscle in specimen (p=0.03) were risk factors for upstaging in RETURBT.Conclusions: NMIBC have high incidence of residual disease and upstaging after primary TURBT. T1 stage, high tumour grade, CIS, and multifocality are risk factors for residual disease after primary TURBT. High tumour grade, CIS and absence of detrusor muscle are strongly associated with upstaging during RETURBT

Critical-Layer Structures and Mechanisms in Elastoinertial Turbulence

Simulations of elastoinertial turbulence (EIT) of a polymer solution at low Reynolds number are shown to display localized polymer stretch fluctuations. These are very similar to structures arising from linear stability (Tollmien-Schlichting modes) and resolvent analyses, i.e., critical-layer structures localized where the mean fluid velocity equals the wave speed. Computations of self-sustained nonlinear Tollmien-Schlichting waves reveal that the critical layer exhibits stagnation points that generate sheets of large polymer stretch. These kinematics may be the genesis of similar structures in EIT

Gathering Global Perspectives to Establish the Research Priorities and Minimum Data Sets for Degenerative Cervical Myelopathy:Sampling Strategy of the First Round Consensus Surveys of AO Spine RECODE-DCM

STUDY DESIGN: Survey.INTRODUCTION: AO Spine Research Objectives and Common Data Elements for Degenerative Cervical Myelopathy (AO Spine RECODE-DCM) is an international initiative that aims to accelerate knowledge discovery and improve outcomes by developing a consensus framework for research. This includes defining the top research priorities, an index term and a minimum data set (core outcome set and core data elements set - core outcome set (COS)/core data elements (CDE)).OBJECTIVE: To describe how perspectives were gathered and report the detailed sampling characteristics.METHODS: A two-stage, electronic survey was used to gather and seek initial consensus. Perspectives were sought from spinal surgeons, other healthcare professionals and people with degenerative cervical myelopathy (DCM). Participants were allocated to one of two parallel streams: (1) priority setting or (2) minimum dataset. An email campaign was developed to advertise the survey to relevant global stakeholder individuals and organisations. People with DCM were recruited using the international DCM charity Myelopathy.org and its social media channels. A network of global partners was recruited to act as project ambassadors. Data from Google Analytics, MailChimp and Calibrum helped optimise survey dissemination.RESULTS: Survey engagement was high amongst the three stakeholder groups: 208 people with DCM, 389 spinal surgeons and 157 other healthcare professionals. Individuals from 76 different countries participated; the United States, United Kingdom and Canada were the most common countries of participants.CONCLUSION: AO Spine RECODE-DCM recruited a diverse and sufficient number of participants for an international PSP and COS/CDE process. Whilst PSP and COS/CDE have been undertaken in other fields, to our knowledge, this is the first time they have been combined in one process.</p