Experimental Study on Viscoelastic Fluid-Structure Interactions

It is well known that when a flexible or flexibly-mounted structure is placed perpendicular to the flow of a Newtonian fluid, it can oscillate due to the shedding of separated vortices at high Reynolds numbers. If the same flexible object is placed in non-Newtonian flows, however, the structure\u27s response is still unknown. The main objective of this thesis is to introduce a new field of viscoelastic fluid-structure interactions by showing that the elastic instabilities that occur in the flow of viscoelastic fluids can drive the motion of a flexible structure placed in its path. Unlike Newtonian fluids, the flow of viscoelastic fluids can become unstable at infinitesimal Reynolds numbers due to the onset of a purely elastic flow instability. This instability occurs in the absence of nonlinear effects of fluid inertia and the Reynolds number of the flows studied here are in the order of 10-4. When such an elastic flow instability occurs in the vicinity of a flexible structure, the fluctuating fluid forces exerted on the structure grow large enough to cause a structural instability which in turn feeds back into the fluid resulting in a flow instability. Nonlinear periodic oscillations of the flexible structure are observed which have been found to be coupled to the time-dependent growth and decay of viscoelastic stresses in the wake of the structure. Presented in this thesis are the results of an investigation of the interaction occurring in the flow of a viscoelastic wormlike micelle solution past a flexible rectangular sheet. The structural geometries studied include: flexible sheet inclinations at 20°, 45° and 90° and flexible sheet widths of 5mm and 2.5mm. By varying the flow velocity, the response of the flexible sheet has been characterized in terms of amplitude and frequency of oscillations. Steady and dynamic shear rheology and filament stretching extensional rheology measurements are conducted in order to characterize the viscoelastic wormlike micelle solution. Bright field images show the deformation of the flexible sheet during an unstable oscillation while flow-induced birefringence images highlight the viscoleastic fluid stresses produced in the wake of the flexible sheet

Experimental Study of Viscoelastic Fluid-Structure Interactions

It is well known that when a flexible or flexibly-mounted structure is placed perpendicular to a Newtonian fluid flow, it can oscillate due to the shedding of vortices at high Reynolds numbers. Unlike Newtonian fluids, viscoelastic fluid flow can become unstable even at infinitesimal Reynolds numbers due to a purely elastic flow instability occurring at large Weissenberg numbers. This thesis focuses on exploring the mechanisms of viscoelastic fluid-structure interactions (VFSI) through experimental investigations on several different combinations of flexible and flexibly-mounted circular cylinders, micro and macro-scale cantilevered beams and viscoelastic fluids such as wormlike micelle solutions and polymer solutions. VFSI study of a flexible cylinder in a flow of wormlike micelle solution is presented where the fluctuating fluid forces exerted on the structure from the elastic flow instabilities lead to a dynamic coupling between the oscillatory structural motion and fluid flow. The presence of a viscoelastic lock-in is reported, for the first time, through a set of experiments where the frequency of the elastic instabilities and the natural frequency of the flexible structure become equal as the flow velocity was increased. Unlike Newtonian fluid-structure interactions, where lock-in corresponds to the maximum observed amplitude of oscillations, in VFSI, the amplitude of oscillations reached a plateau while in lock-in, but increased with Weissenberg number and reduced velocity before and after lock-in. Microfluidic VFSI of a polymer solution flowing past a cantilevered beam is investigated for varying beam flexibility and Weissenberg number as the flow field transitioned from a stable detached vortex upstream of the beam to a time-dependent unstable vortex shedding. The oscillations of the beam were observed to show two distinct regimes: a clear single vortex shedding regime, and another characterized by 3D chaotic-like instabilities. Finally, VFSI of a cantilevered beam in a flow of wormlike micelle solution is studied as a function of the beam\u27s tip angle. For beams with small tip angles of 0o and 25o, no oscillation was observed. However, for beams with larger tip angles of 45o and 65o, an oscillatory motion coupled to the flow instability was observed, where the amplitude of the beam oscillations increased with increasing tip angle

Distance matrix of enhanced power graphs of finite groups

The enhanced power graph of a group $G$ is the graph $\mathcal{G}_E(G)$ with vertex set $G$ and edge set \{(u,v): u, v \in \langle w \rangle,~\mbox{for some}~ w \in G\}. In this paper, we compute the spectrum of the distance matrix of the enhanced power graph of non-abelian groups of order $pq$, dihedral groups, dicyclic groups, elementary abelian groups \El(p^n) and the non-cyclic abelian groups \El(p^n)\times \El(q^m) and \El(p^n)\times \mathbb{Z}_m, where $p$ and $q$ are distinct primes. For the non-cyclic abelian group \El(p^n)\times \El(q^m), we also compute the spectrum of the adjacency matrix of its enhanced power graph and the spectrum of the adjacency and the distance matrix of its power graph

Factors affecting delayed and non-receipt of healthcare during the COVID-19 pandemic for women in rural Maharashtra, India:Evidence from a cross-sectional study

BACKGROUND: Pathways to low healthcare utilisation under the COVID-19 pandemic are not well understood. This study aims to understand women's concerns about the health system's priorities and their increased burden of domestic responsibilities during COVID-19 as predictors of delayed or non-receipt of needed care for themselves or their children. METHODS: We surveyed married women in rural Maharashtra, India (N = 1021) on their health and economic concerns between Feb 1 and March 26, 2021. This study period was when India emerged from the first wave of the pandemic, which had severely impacted the health systems, and before the second—even more devastating wave had started. We captured if women were concerned about access to non-COVID health services due to healthcare being directed solely to COVID-19) (exposure 1) and whether their domestic responsibilities increased during the pandemic (exposure 2). Our outcomes included women's reports on whether they delayed healthcare seeking (secondary outcome and mediator) and whether they received healthcare for themselves or their children when needed (primary outcome). We conducted adjusted regression models on our predictor variables with each outcome and assessed the mediation effects of delayed healthcare seeking for each of the exposure variables. FINDINGS: We found that women who were concerned that healthcare was directed solely towards COVID-19 were more likely not to receive healthcare when needed (Adjusted Risk Ratio [ARR] = 1.49, 95% CI = 1.14, 1.95). We also found that women whose domestic care burden increased under the pandemic were more likely to delay healthcare seeking (ARR = 1.84, 95% CI = 1.05, 3.21). Delayed healthcare seeking mediated the associations between each of our exposure variables with our outcome variable, non-receipt of needed healthcare. INTERPRETATION: Our findings suggested that women's perceptions of healthcare systems and their domestic labour burdens affected healthcare seeking during the pandemic in India, even before the second wave of COVID-19 incapacitated the health system. Support for women and health systems is needed to ensure healthcare uptake during crises. FUNDING: Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, USA (grant numbers: R01HD084453- 01A1 and RO1HD61115); Department of Biotechnology, Government of India (grant #BT/IN/US/01/BD/2010); the EMERGE project (Bill and Melinda Gates Foundation Grants: OPP1163682 and INV018007; PI Anita Raj), and Bill and Melinda Gates Foundation Grant number INV-002967

The associations of everyday and major discrimination exposure with violence and poor mental health outcomes during the COVID-19 pandemic

Research on discrimination and risks for violence and mental health issues under the pandemic is notably absent. We examined the relative effects of perceived everyday discrimination (e.g., poorer service, disrespectful treatment in a typical week) and major experiences of race-based discrimination (e.g., racial/ethnic discrimination in housing or employment at any point in the lifetime) on experiences of violence and the PHQ-4 assessment of symptoms of depression and anxiety under the pandemic. We analyzed state-representative cross-sectional survey data from California adults (N = 2114) collected in March 2021. We conducted multivariate regression models adjusting for age, race/ethnicity, gender, sexual identity, income, and disability. One in four Californians (26.1%) experienced everyday discrimination in public spaces, due most often to race/ethnicity and gender. We found that everyday discrimination was significantly associated with past year physical violence (single form Adjusted Odds Ratio [AOR] 5.0, 95% CI 2.5–10.3; multiple forms AOR 2.6, 95% CI 1.1–5.8), past year sexual violence (multiple forms AOR 2.5, 95% CI 1.4–4.4), and mental health symptoms (e.g., severe symptoms, multiple forms AOR 3.3, 95% CI 1.6–6.7). Major experiences of race-based discrimination (reported by 10.0% of Californians) were associated with past year sexual violence (AOR 2.0, 95% CI 1.1–3.8) and severe mental health symptoms (AOR 2.7, 95% CI 1.2–6.2). Non-race-based major discrimination (reported by 23.9% of Californians) was also associated with violence and mental health outcomes Everyday discrimination, more than major experiences of discrimination, was associated with higher risk for violence and poor mental health outcomes during the pandemic. Non-race-based forms of major discrimination independently were also associated with these negative outcomes. Findings indicate that efforts to reduce and ultimately eliminate discrimination should be a focus of public health and COVID-19 rebuilding efforts

Building the Games Students Want to Play: BiblioBouts Project Interim Report #2

The University of Michigan’s School of Information and its partner, the Center for History and New Media at George Mason University, are undertaking the 3-year BiblioBouts Project (October 1, 2008 to September 30, 2011) to support the design, development, testing, and evaluation of a computer game to teach incoming undergraduate students information literacy skills and concepts. This second interim report describes the project team’s 5-month progress achieving 2 of the project’s 4 objectives, designing the BiblioBouts game and engaging in evaluation activities. It also enumerates major tasks that will occupy the team for the next 6 months. Appendixes A and B describe the game’s design and include pedagogical goals and how the game scores players.Institute of Museum and Library Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/64293/1/bbInterimReportToIMLS02.pd

Building the Games Students Want to Play: BiblioBouts Project Interim Report #3

The University of Michigan's School of Information and its partner, the Center for History and New Media at George Mason University, are undertaking the 3-year BiblioBouts Project (October 1, 2008 to September 30, 2011) to support the design, development, testing, and evaluation of the web-based BiblioBouts game to teach incoming undergraduate students information literacy skills and concepts. This third interim report describes the BiblioBouts Project team’s 6-month progress achieving the project's 4 objectives: designing, developing, deploying, and evaluating the BiblioBouts game and recommending best practices for future information literacy games. This latest 6-month period was marked by extensive progress in the deployment and evaluation of the alpha version of BiblioBouts. Major tasks that will occupy the team for the next 6 months are applying evaluation findings to game redesign and enhancement. For general information about game design, pedagogical goals, scoring, game play, project participants, and playing BiblioBouts in your course, consult the BiblioBouts Project web site.Institute of Museum and Library Serviceshttp://deepblue.lib.umich.edu/bitstream/2027.42/69157/1/bbInterimReportToIMLS03.pd

BHPR research: qualitative1. Complex reasoning determines patients' perception of outcome following foot surgery in rheumatoid arhtritis

Background: Foot surgery is common in patients with RA but research into surgical outcomes is limited and conceptually flawed as current outcome measures lack face validity: to date no one has asked patients what is important to them. This study aimed to determine which factors are important to patients when evaluating the success of foot surgery in RA Methods: Semi structured interviews of RA patients who had undergone foot surgery were conducted and transcribed verbatim. Thematic analysis of interviews was conducted to explore issues that were important to patients. Results: 11 RA patients (9 ♂, mean age 59, dis dur = 22yrs, mean of 3 yrs post op) with mixed experiences of foot surgery were interviewed. Patients interpreted outcome in respect to a multitude of factors, frequently positive change in one aspect contrasted with negative opinions about another. Overall, four major themes emerged. Function: Functional ability & participation in valued activities were very important to patients. Walking ability was a key concern but patients interpreted levels of activity in light of other aspects of their disease, reflecting on change in functional ability more than overall level. Positive feelings of improved mobility were often moderated by negative self perception ("I mean, I still walk like a waddling duck”). Appearance: Appearance was important to almost all patients but perhaps the most complex theme of all. Physical appearance, foot shape, and footwear were closely interlinked, yet patients saw these as distinct separate concepts. Patients need to legitimize these feelings was clear and they frequently entered into a defensive repertoire ("it's not cosmetic surgery; it's something that's more important than that, you know?”). Clinician opinion: Surgeons' post operative evaluation of the procedure was very influential. The impact of this appraisal continued to affect patients' lasting impression irrespective of how the outcome compared to their initial goals ("when he'd done it ... he said that hasn't worked as good as he'd wanted to ... but the pain has gone”). Pain: Whilst pain was important to almost all patients, it appeared to be less important than the other themes. Pain was predominately raised when it influenced other themes, such as function; many still felt the need to legitimize their foot pain in order for health professionals to take it seriously ("in the end I went to my GP because it had happened a few times and I went to an orthopaedic surgeon who was quite dismissive of it, it was like what are you complaining about”). Conclusions: Patients interpret the outcome of foot surgery using a multitude of interrelated factors, particularly functional ability, appearance and surgeons' appraisal of the procedure. While pain was often noted, this appeared less important than other factors in the overall outcome of the surgery. Future research into foot surgery should incorporate the complexity of how patients determine their outcome Disclosure statement: All authors have declared no conflicts of interes

Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of $t\overline{t}$, $W+b\overline{b}$ and $W+c\overline{c}$ is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 $\pm$ 0.02 \mbox{fb}^{-1}. The $W$ bosons are reconstructed in the decays $W\rightarrow\ell\nu$, where $\ell$ denotes muon or electron, while the $b$ and $c$ quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions