A theory of sound transmission through a clamped curved piezoelectric membrane connected to a negative capacitor

An analytical calculation of the acoustic transmission loss of sound propagating through a thin cylindrically curved piezoelectric membrane, which is rigidly clamped at its straight ends, is presented. The membrane is placed inside an acoustic tube and connected to an active electric shunt circuit that behaves as a negative capacitor. A properly adjusted shunt circuit has a significant impact on the effective elastic stiffness of the piezoelectric membrane and, hence, influences the membrane acoustic reflectivity and transmission loss of sound. Such a setup represents a noise control system based on the principles of the active elasticity control of piezoelectric materials. The non-uniform radial motion of the clamped membrane and its interaction with the acoustic field and the electric shunt circuit are analyzed. The main objective of the calculations, which are based on Donnell's theory, is the determination of the effects of the membrane clamps on the flexural motion of the membrane and, therefore, effects on the acoustic transmission loss of sound. Approximative formulae for the amplitude of the membrane displacement and the acoustic transmission loss of sound are expressed as well as the resonant frequencies of the uniform mode and flexural vibration modes

Examining sex differences in knee pain: the Multicenter Osteoarthritis Study

SummaryObjectiveTo determine whether women experience greater knee pain severity than men at equivalent levels of radiographic knee osteoarthritis (OA).Design and methodsA cross-sectional analysis of 2712 individuals (60% women) without knee replacement or a recent steroid injection. Sex differences in pain severity at each Kellgren–Lawrence (KL) grade were assessed by knee using visual analog scale (VAS) scale and Western Ontario and McMaster Universities Arthritis Index (WOMAC) with and without adjustment for age, analgesic use, Body mass index (BMI), clinic site, comorbid conditions, depression score, education, race, and widespread pain (WSP) using generalized estimating equations. Effect sizes (Cohen's d) were also calculated. Analyses were repeated in those with and without patellofemoral OA (PFOA).ResultsWomen reported higher VAS pain at all KL grades in unadjusted analyses (d = 0.21–0.31, P < 0.0001–0.0038) and in analyses adjusted for all covariates except WSP (d = 0.16–0.22, P < 0.0001–0.0472). Pain severity differences further decreased with adjustment for WSP (d = 0.10–0.18) and were significant for KL grade ≤2 (P = 0.0015) and 2 (P = 0.0200). Presence compared with absence of WSP was associated with significantly greater knee pain at all KL grades (d = 0.32–0.52, P < 0.0001–0.0008). In knees with PFOA, VAS pain severity sex differences were greater at each KL grade (d = 0.45–0.62, P = 0.0006–0.0030) and remained significant for all KL grades in adjusted analyses (d = 0.31–0.57, P = 0.0013–0.0361). Results using WOMAC were similar.ConclusionsWomen reported greater knee pain than men regardless of KL grade, though effect sizes were generally small. These differences increased in the presence of PFOA. The strong contribution of WSP to sex differences in knee pain suggests that central sensitivity plays a role in these differences

Review article: Towards strongly coupled ensemble data assimilation with additional improvements from machine learning

We assessed different coupled data assimilation strategies with a hierarchy of coupled models, ranging from a simple coupled Lorenz model to the state-of-the-art coupled general circulation model CFSv2 (Climate Forecast System version 2). With the coupled Lorenz model, we assessed the analysis accuracy by strongly coupled ensemble Kalman filter (EnKF) and 4D-Variational (4D-Var) methods with varying assimilation window lengths. The analysis accuracy of the strongly coupled EnKF with a short assimilation window is comparable to that of 4D-Var with a long assimilation window. For 4D-Var, the strongly coupled approach with the coupled model produces more accurate ocean analysis than the Estimating the Circulation and Climate of the Ocean (ECCO)-like approach using the uncoupled ocean model. Experiments with the coupled quasi-geostrophic model conclude that the strongly coupled approach outperforms the weakly coupled and uncoupled approaches for both the full-rank EnKF and 4D-Var, with the strongly coupled EnKF and 4D-Var showing a similar level of accuracy higher than other coupled data assimilation approaches such as outer-loop coupling. A strongly coupled EnKF software framework is developed and applied to the intermediate-complexity coupled model SPEEDY-NEMO and the state-of-the-art operational coupled model CFSv2. Experiments assimilating synthetic or real atmospheric observations into the ocean through strongly coupled EnKF show that the strongly coupled approach improves the analysis of the atmosphere and upper ocean but degrades observation fits in the deep ocean, probably due to the unreliable error correlation estimated by a small ensemble. The correlation-cutoff method is developed to reduce the unreliable error correlations between physically irrelevant model states and observations. Experiments with the coupled Lorenz model demonstrate that strongly coupled EnKF informed by the correlation-cutoff method produces more accurate coupled analyses than the weakly coupled and plain strongly coupled EnKF regardless of the ensemble size. To extend the correlation-cutoff method to operational coupled models, a neural network approach is proposed to systematically acquire the observation localization functions for all pairs between the model state and observation types. The following strongly coupled EnKF experiments with an intermediate-complexity coupled model show promising results with this method.</p

Assistants, Guides, Collaborators, Friends: The Concealed Figures of Conflict Research

Recent scholarship has demonstrated an increasing awareness of the need for more grounded, empirical research into the micro-level dynamics of violent contexts. Research in these difficult, dangerous, and potentially violent conflict or post-conflict settings necessitates the formation of new relationships of dependency, and assistants, friends, collaborators, and guides become central figures in the field. However, all too often, these figures are written out of academic accounts and silenced in our analyses. This not only does them a significant disservice, but it also obscures potential biases, complexities, and ethical dilemmas that emerge in the way in which such research is carried out. Drawing upon fieldwork exploring the 2007–2008 Kenyan postelection violence, this paper argues that reliance upon insider-assistants is essential in conflict settings and explores the challenges inherent in these relationships. As researchers become increasingly engaged in micro-level studies of violent contexts, we must interrogate the realities of how our knowledge has been produced and engage in more open and honest discussions of the methodological and ethical challenges of conflict research

Short-term efficacy of physical interventions in osteoarthritic knee pain. A systematic review and meta-analysis of randomised placebo-controlled trials.

BACKGROUND: Treatment efficacy of physical agents in osteoarthritis of the knee (OAK) pain has been largely unknown, and this systematic review was aimed at assessing their short-term efficacies for pain relief. METHODS: Systematic review with meta-analysis of efficacy within 1-4 weeks and at follow up at 1-12 weeks after the end of treatment. RESULTS: 36 randomised placebo-controlled trials (RCTs) were identified with 2434 patients where 1391 patients received active treatment. 33 trials satisfied three or more out of five methodological criteria (Jadad scale). The patient sample had a mean age of 65.1 years and mean baseline pain of 62.9 mm on a 100 mm visual analogue scale (VAS). Within 4 weeks of the commencement of treatment manual acupuncture, static magnets and ultrasound therapies did not offer statistically significant short-term pain relief over placebo. Pulsed electromagnetic fields offered a small reduction in pain of 6.9 mm [95% CI: 2.2 to 11.6] (n = 487). Transcutaneous electrical nerve stimulation (TENS, including interferential currents), electro-acupuncture (EA) and low level laser therapy (LLLT) offered clinically relevant pain relieving effects of 18.8 mm [95% CI: 9.6 to 28.1] (n = 414), 21.9 mm [95% CI: 17.3 to 26.5] (n = 73) and 17.7 mm [95% CI: 8.1 to 27.3] (n = 343) on VAS respectively versus placebo control. In a subgroup analysis of trials with assumed optimal doses, short-term efficacy increased to 22.2 mm [95% CI: 18.1 to 26.3] for TENS, and 24.2 mm [95% CI: 17.3 to 31.3] for LLLT on VAS. Follow-up data up to 12 weeks were sparse, but positive effects seemed to persist for at least 4 weeks after the course of LLLT, EA and TENS treatment was stopped. CONCLUSION: TENS, EA and LLLT administered with optimal doses in an intensive 2-4 week treatment regimen, seem to offer clinically relevant short-term pain relief for OAK

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011