Diagnostic criteria for early hip osteoarthritis: first steps, based on the CHECK study

Objectives. Although there is a general focus on early diagnosis and treatment of hip OA, there are no validated diagnostic criteria for early-stage hip OA. The current study aimed to take the first steps in developing diagnostic criteria for early-stage hip OA, using factors obtained through history taking, physical examination, radiography and blood testing at the first consultation in individuals presenting with hip pain, suspicious for hip OA, in primary care.Methods. Data of the 543 individuals with 735 symptomatic hips at baseline who had any follow-up data available from the prospective CHECK cohort study were used. A group of 26 clinical experts [general practitioners (GPs), rheumatologists and orthopaedic surgeons] evaluated standardized clinical assessment forms of all subjects on the presence of clinically relevant hip OA 5-10 years after baseline. Using the expert-based diagnoses as reference standard, a backward selection method was used to create predictive models based on pre-defined baseline factors from history taking, physical examination, radiography and blood testing.Results. Prevalence of clinically relevant hip OA during follow-up was 22%. Created models contained four to eight baseline factors (mainly WOMAC pain items, painful/restricted movements and radiographic features) and obtained area under the curve between 0.62 (0.002) and 0.71 (0.002).Conclusion. Based on clinical and radiographic features of hip OA obtained at first consultation at a GP for pain/stiffness of the hip, the prediction of clinically relevant hip OA within 5-10 years was 'poor' to /fair'.Clinical epidemiolog

Self-adaptive approach for optimisation of passive control systems for seismic resistant buildings

The concept of passive control of the seismic response of structures was introduced to improve the performance of structures by increasing their energy dissipation and reduce or eliminate damage in the structural elements. The key task in the design of passive systems is to determine the forces in the control devices (yield/slip or post-tensioning) at each floor, that will result in best performance (e.g. minimum inter-storey drift). This can be achieved by large parametric studies in which both the maximum control force (e.g. at ground level) and the distribution of forces along the height of the structure are varied. Alternatively, optimum forces in the devices can be achieved by semi-active control, where the structure self-adapts to the earthquake. Both solutions are expensive: the first requires hundreds of non-linear response simulations in the design stage; the second needs a system of sensors, controllers and electromechanical devices. Presented here is a new Self Adaptive Optimisation Approach (SAOA) in which the self-optimisation of a semi-active system is used in the design stage and the resulting distribution of control forces is adopted as a passive system. The new approach was evaluated through comparing the simulated dynamic responses of two relatively simple benchmark structures (braced and post-tensioned) with three sets of control forces: (1) passive system with forces obtained in parametric study, (2) semi-active system with self-adapting control forces, and (3) passive system with SAOA-optimized forces. The results show good performance of the SAOA systems, indicating that SAOA offers a simple and effective solution that can replace the existing optimisation approaches for the design of passively controlled earthquake resistant structures. This study presents a novel idea of using the semi-active control as a tool for optimising a passive control system. The passive control systems can be further improved by a larger study in which the semi-active control algorithms are also optimised

Re-centering variable friction device for seismic control of structures

Abstract: This paper investigates the seismic response control of a nonlinear benchmark building with a new re-centering variable friction device (RVFD). The RVFD consists of three parts: (i) a friction generation unit, (ii) a piezoelectric actuator, and (iii) shape memory alloy wires. The friction unit and piezoelectric actuator compose the first subcomponent of the hybrid device that is a variable friction damper (VFD). The clamping force of the VFD can be adjusted according to the current level of ground motion by adjusting the voltage level of piezoelectric actuators. The second subcomponent of this hybrid device consists of shape memory alloy (SMA) wires that exhibit a unique hysteretic behavior and full recovery following post-yielding deformations. In general, installed SMA devices have the ability to re-center structures upon end of the motion and VFDs can increase the energy dissipation capacity of structures. The full realization of these devices into a singular, hybrid form which complements the performance of each device is investigated. A neuro-fuzzy model is used to capture rate-and temperature-dependent nonlinear behavior of the SMA components of the hybrid device. A fuzzy logic controller is developed to adjust voltage level of VFDs for favorable performance in a RVFD hybrid application. Numerical simulations of seismically excited nonlinear benchmark building are conducted to evaluate the performance of the hybrid device. Results show that the RVFD modulated with a fuzzy logic control strategy can effectively reduce interstory drifts without increasing acceleration response of the benchmark building for most cases

On the sph modeling of flow over cylinder beneath to a free-surface

This work aims to model flow around rigid cylinder beneath to a free surface by using a particle based Lagrangian method, namely, Smoothed Particle Hydrodynamics (SPH) which has clear advantages on modeling nonlinear violent free surface problems. This problem which is also regarded as 2-d wave making problem in marine hydrodynamics literature is carried out for three different positions of cylinder centre with two different Froude numbers. The fluid motion is governed by continuity and Eulers equations while Weakly Compressible SPH (WCSPH) approximation together with artificial viscosity term is employed for the numerical discretization of the problem domain. Hybrid Velocity- updated XSPH and Articial Particle Displacement (VXSPH+APD) correction algorithm [1] and standard density correction treatment is also added into the numerical scheme. The Reynolds number is chosen as close to 200 for all cases where three dimensionality first starts to be effective in the flow domain [2]. As the flow characteristics are metastable [12], the free-surface deformations, drag and the lift force on the body shows periodic variation during the evolution of the flow. Free-surface deformations at the maximum and minimum lift instants are compared with the results of Reichl et.al. [12] for the first two cases. The last case considers a higher Froude number and deeper cylinder position where lift and drag forces are compared with the findings of [22]. It is observed that the obtained free-surface profiles, mean values of drag and lift forces give consistent results in a good with the referred literature data

Is valproate promising in cardiac fatal arrhythmias? Comparison of P- and Q-wave dispersion in bipolar affective patients on valproate or lithium-valproate maintenance therapy with healthy controls

Autonomic nerve system is considered to be involved in bipolar affective disorder (BAD) or to be influenced by valproate monotherapy or valproate plus lithium combination. We planned to assess the effects of medication on atrial and ventricular conduction. The electrocardiography records were performed with eligible 15 patients with valproate, 20 patients with lithium-valproate combination use in euthymic phases of BAD and 20 healthy participants. The blood valproate and lithium concentrations in groups were in normal range. The difference in P maximum, P minimum, maximum QTc were statistically insignificant. Minimum QTc (F = 6.36; df = 2; P = 0.003) and QT dispersion (QTD) (F = 5.57; df = 2; P = 0.006) were statistically significant among the groups. There were no significant differences between patient groups among ECG parameters. Minimum QTc was significantly longer in combination group than healthy controls, whereas the QTD values in both patient groups were significantly lower than controls'. Valproate might have some preventive effects on ventricular electrical conduction because of lower QTD in both patient groups. Thus, valproate seems to have cardiac conduction stabilizing effect beside its mood stabilizing aspect. However, this finding needs replication and further corroboration in well-designed studies

An investigation into the nonlinear effects in the roll motion of 2-D bodies by SPH method

Nonlinear effects in the roll motion of a 2–D body in the free surface are investigated by utilizing the Smoothed Particle Hydrodynamics (SPH) method. The continuity and Navier–Stokes equations are solved by employing the Weakly Compressible SPH (WCSPH) approach and our in-house code, which relies on the accumulated development process through the authors’ previous works including the fluid–solid coupling modeling by viscous penalty technique, (Tofighi et al. (2015)), and a hybrid Velocity-Variance Free Surface (VFS) and Artificial Particle Displacement (APD) algorithm (Ozbulut et al., 2014, 2018, 2020; Kolukisa et al., 2020). In this work, the GPU parallelization of the code is performed, to mitigate the computational burdens of the relatively high number of particles due to the long wavelengths generated by the roll motion of the cylinder. Presently, an alternative and exact approach in reducing the equation of roll motion with quadratic damping term is introduced. In parallel to this approach, a quadratic regression equation approximating the hydrodynamic roll moment is also employed. Aside from hydrodynamic coefficients, with linear and quadratic damping coefficients, vortex flow characteristics are also presented, qualitatively and quantitatively. It is understood from the results that, with the present capability, the WCSPH approach introduced is able to disclose nonlinearities inherently exist in the roll motion of oscillatory bodies in the free surface