Takens-Bogdanov bifurcation of travelling wave solutions in pipe flow

The appearance of travelling-wave-type solutions in pipe Poiseuille flow that are disconnected from the basic parabolic profile is numerically studied in detail. We focus on solutions in the 2-fold azimuthally-periodic subspace because of their special stability properties, but relate our findings to other solutions as well. Using time-stepping, an adapted Krylov-Newton method and Arnoldi iteration for the computation and stability analysis of relative equilibria, and a robust pseudo-arclength continuation scheme we unfold a double-zero (Takens-Bogdanov) bifurcating scenario as a function of Reynolds number (Re) and wavenumber (k). This scenario is extended, by the inclusion of higher order terms in the normal form, to account for the appearance of supercritical modulated waves emanating from the upper branch of solutions at a degenerate Hopf bifurcation. These waves are expected to disappear in saddle-loop bifurcations upon collision with lower-branch solutions, thereby leaving stable upper-branch solutions whose subsequent secondary bifurcations could contribute to the formation of the phase space structures that are required for turbulent dynamics at higher Re.Comment: 26 pages, 15 figures (pdf and png). Submitted to J. Fluid Mec

From travelling waves to mild chaos: a supercritical bifurcation cascade in pipe flow

We study numerically a succession of transitions in pipe Poiseuille flow that leads from simple travelling waves to waves with chaotic time-dependence. The waves at the origin of the bifurcation cascade possess a shift-reflect symmetry and are both axially and azimuthally periodic with wave numbers {\kappa} = 1.63 and n = 2, respectively. As the Reynolds number is increased, successive transitions result in a wide range of time dependent solutions that includes spiralling, modulated-travelling, modulated-spiralling, doubly-modulated-spiralling and mildly chaotic waves. We show that the latter spring from heteroclinic tangles of the stable and unstable invariant manifolds of two shift-reflect-symmetric modulated-travelling waves. The chaotic set thus produced is confined to a limited range of Reynolds numbers, bounded by the occurrence of manifold tangencies. The states studied here belong to a subspace of discrete symmetry which makes many of the bifurcation and path-following investigations presented technically feasible. However, we expect that most of the phenomenology carries over to the full state-space, thus suggesting a mechanism for the formation and break-up of invariant states that can sustain turbulent dynamics.Comment: 38 pages, 35 figures, 1 tabl

Statistical analysis of coherent structures in transitional pipe flow

Numerical and experimental studies of transitional pipe flow have shown the prevalence of coherent flow structures that are dominated by downstream vortices. They attract special attention because they contribute predominantly to the increase of the Reynolds stresses in turbulent flow. In the present study we introduce a convenient detector for these coherent states, calculate the fraction of time the structures appear in the flow, and present a Markov model for the transition between the structures. The fraction of states that show vortical structures exceeds 24% for a Reynolds number of about Re=2200, and it decreases to about 20% for Re=2500. The Markov model for the transition between these states is in good agreement with the observed fraction of states, and in reasonable agreement with the prediction for their persistence. It provides insight into dominant qualitative changes of the flow when increasing the Reynolds number.Comment: 11 pages, 26 (sub)figure

Establishing General Working Population Norms for the Cognitive Symptom Checklist-Work

PURPOSE: The Cognitive Symptom Checklist-Work (CSC-W) is a self-report measure to assess cognitive symptoms (i.e., memory and executive function) in working adults with cancer. To date, general working population norm data are lacking worldwide. We established CSC-W norm values in the general working population, and assessed associations of CSC-W scores with work and health-related factors.METHODS: This cross-sectional study consisted of 1,000 Dutch working adults, of whom data was collected through an online respondent panel. The sample was stratified for sex and age, and data were weighted. Summary scores of the CSC-W total scale, and memory and executive function symptoms subscales, were determined (e.g., means, percentiles). Z- and T-scores were calculated, and analysis of (co)variance has been applied.RESULTS: Cognitive symptom scores were relatively stable across age groups, but 18-39-year-old respondents reported lower memory and executive function than respondents in other age groups. Symptom scores of memory function (mean 29.1; SD = 16.7) were higher for all age groups and in both sexes compared to executive function (mean 22.1; SD = 16.8). No sex differences in memory and executive function were observed. Higher symptom scores were associated with performing non-manual work only, manual work only, self-reported long-term illness, and higher levels of depressive symptoms and fatigue.CONCLUSION: The CSC-W norms may enhance the interpretation and facilitate the analysis of self-reported cognitive symptoms in patients with cancer at work. Our findings may support health care professionals in identifying working adults with cancer with cognitive symptoms and in developing personalized treatment.</p

Differences in management approaches for lupus nephritis within the UK

\ua9 The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology.Objectives: Outcomes of therapy for LN are often suboptimal. Guidelines offer varied options for treatment of LN and treatment strategies may differ between clinicians and regions. We aimed to assess variations in the usual practice of UK physicians who treat LN. Methods: We conducted an online survey of simulated LN cases for UK rheumatologists and nephrologists to identify treatment preferences for class IV and class V LN. Results: Of 77 respondents, 48 (62.3%) were rheumatologists and 29 (37.7%) were nephrologists. A total of 37 (48.0%) reported having a joint clinic between nephrologists and rheumatologists, 54 (70.0%) reported having a multidisciplinary team meeting for LN and 26 (33.7%) reported having a specialized lupus nurse. Of the respondents, 58 (75%) reported arranging a renal biopsy before starting the treatment. A total of 20 (69%) of the nephrologists, but only 13 (27%) rheumatologists, reported having a formal departmental protocol for treating patients with LN (P &lt; 0.001). The first-choice treatment of class IV LN in pre-menopausal patients was MMF [41 (53.2%)], followed by CYC [15 (19.6%)], rituximab [RTX; 12 (12.5%)] or a combination of immunosuppressive drugs [9 (11.7%)] with differences between nephrologists’ and rheumatologists’ choices (P \ubc 0.026). For class V LN, MMF was the preferred initial treatment, irrespective of whether proteinuria was in the nephrotic range or not. RTX was the preferred second-line therapy for non-responders. Conclusion: There was variation in the use of protocols, specialist clinic service provision, biopsies and primary and secondary treatment choices for LN reported by nephrologists and rheumatologists in the UK

Establishing General Working Population Norms for the Cognitive Symptom Checklist-Work

PURPOSE: The Cognitive Symptom Checklist-Work (CSC-W) is a self-report measure to assess cognitive symptoms (i.e., memory and executive function) in working adults with cancer. To date, general working population norm data are lacking worldwide. We established CSC-W norm values in the general working population, and assessed associations of CSC-W scores with work and health-related factors.METHODS: This cross-sectional study consisted of 1,000 Dutch working adults, of whom data was collected through an online respondent panel. The sample was stratified for sex and age, and data were weighted. Summary scores of the CSC-W total scale, and memory and executive function symptoms subscales, were determined (e.g., means, percentiles). Z- and T-scores were calculated, and analysis of (co)variance has been applied.RESULTS: Cognitive symptom scores were relatively stable across age groups, but 18-39-year-old respondents reported lower memory and executive function than respondents in other age groups. Symptom scores of memory function (mean 29.1; SD = 16.7) were higher for all age groups and in both sexes compared to executive function (mean 22.1; SD = 16.8). No sex differences in memory and executive function were observed. Higher symptom scores were associated with performing non-manual work only, manual work only, self-reported long-term illness, and higher levels of depressive symptoms and fatigue.CONCLUSION: The CSC-W norms may enhance the interpretation and facilitate the analysis of self-reported cognitive symptoms in patients with cancer at work. Our findings may support health care professionals in identifying working adults with cancer with cognitive symptoms and in developing personalized treatment.</p

Efficacy and safety of obinutuzumab in systemic lupus erythematosus patients with secondary non-response to rituximab

OBJECTIVE: Secondary inefficacy with infusion reactions and anti-drug antibodies (secondary non-depletion nonresponse, 2NDNR) occurs in 14% of SLE patients receiving repeated rituximab courses. We evaluated baseline clinical characteristics, efficacy and safety of obinutuzumab, a next-generation humanized type-2 anti-CD20 antibody licensed for haematological malignancies in SLE patients with 2NDNR to rituximab. METHODS: We collated data from SLE patients receiving obinutuzumab for secondary non-response to rituximab in BILAG centres. Disease activity was assessed using BILAG-2004, SLEDAI-2K and serology before, and 6 months after, obinutuzumab 2× 1000 mg infusions alongside methylprednisolone 100 mg. RESULTS: All nine patients included in the study received obinutuzumab with concomitant oral immunosuppression. At 6 months post-obinutuzumab, there were significant reductions in median SLEDAI-2K from 12 to 6 (P = 0.014) and total BILAG-2004 score from 21 to 2 (P = 0.009). Complement C3 and dsDNA titres improved significantly (both P = 0.04). Numerical, but not statistically significant improvements were seen in C4 levels. Of 8/9 patients receiving concomitant oral prednisolone at baseline (all >10 mg/day), 5/8 had their dose reduced at 6 months. Four of nine patients were on 5 mg/day and were in Lupus Low Disease Activity State following obinutuzumab. After obinutuzumab, 6/9 patients with peripheral B cell data achieved complete depletion, including 4/4 assessed with highly sensitive assays. Of the nine patients, one obinutuzumab non-responder required CYC therapy. One unvaccinated patient died from COVID-19. CONCLUSIONS: Obinutuzumab appears to be effective and steroid-sparing in renal and non-renal SLE patients with secondary non-response to rituximab. These patients have severe disease with few treatment options but given responsiveness to B cell depletion, switching to humanized type-2 anti-CD20 therapy is a logical approach

Utility of an attention-based performance validity test for the detection of feigned cognitive dysfunction after acquired brain injury

Introduction: The Groningen Effort Test (GET) is a recently developed performance validity test (PVT) for the identification of noncredible performance in a neuropsychological assessment of attention abilities. Because the majority of already established PVTs are based on memory functions, the GET has the potential to make a valuable contribution to validity testing.Method: The current study examined the utility of the GET in the detection of feigned cognitive dysfunction after acquired brain injury (ABI) and its incremental validity over already established PVTs, namely the Test of Memory Malingering (TOMM), the Dot Counting Test (DCT), and the b Test. Three hundred and forty-eight participants took part in this study, including 58 patients with ABI (stroke or traumatic brain injury), 43 healthy individuals instructed to show normal behavior, and 247 healthy individuals instructed to feign cognitive dysfunction after ABI.Results: With excellent overall classification accuracy, the GET performed close to the level of the TOMM, and superior to the b Test and DCT. Data analyses further revealed that the GET provides additional diagnostic accuracy compared to the b Test and the DCT in the detection of feigned cognitive dysfunction, but has no incremental validity over the TOMM. For each of the four PVTs in this study, diagnostic sensitivity was independent of the simulation strategy used.Conclusions: It is concluded that the GET is an attention-based PVT with promising test characteristics and high diagnostic accuracy in the detection of noncredible cognitive performance using a simulation design. Given the results can be replicated in studies using known-groups methodology, it may be a useful tool for clinical practice to complement neuropsychological assessments of patients with ABI