Functional aplasia of the contralateral A1 segment influences clinical outcome in patients with occlusion of the distal internal carotid artery

Background: The importance of an A1 aplasia remains unclear in stroke patients. In this work, we analyze the impact of an A1 aplasia contralateral to an acute occlusion of the distal internal carotid artery (ICA) on clinical outcomes. Methods: We conducted a retrospective study of consecutive stroke patients treated with mechanical thrombectomy at 12 tertiary care centers between January 2015 and February 2021 due to an occlusion of the distal ICA. Functional A1 aplasia was defined as the absence of A1 or hypoplastic A1 (>50% reduction to the contralateral site). Functional independence was measured by the modified Rankin Scale (mRS ≤ 2). Results: In total, 81 out of 1068 (8%) patients had functional A1 aplasia contralateral to distal ICA occlusion. Patients with functional contralateral A1 aplasia were more severely affected on admission (median NIHSS 18, IQR 15–23 vs. 17, IQR 13–21; aOR: 0.672, 95% CI: 0.448–1.007, p = 0.054) and post-interventional ischemic damage was larger (median ASPECTS 5, IQR 1–7, vs. 6, IQR 3–8; aOR: 1.817, 95% CI: 1.184–2.789, p = 0.006). Infarction occurred more often within the ipsilateral ACA territory (20/76, 26% vs. 110/961, 11%; aOR: 2.482, 95% CI: 1.389–4.437, p = 0.002) and both ACA territories (8/76, 11% vs. 5/961, 1%; aOR: 17.968, 95% CI: 4.979–64.847, p ≤ 0.001). Functional contralateral A1 aplasia was associated with a lower rate of functional independence at discharge (6/81, 8% vs. 194/965, 20%; aOR: 2.579, 95% CI: 1.086–6.122, p = 0.032) and after 90 days (5/55, 9% vs. 170/723, 24%; aOR: 2.664, 95% CI: 1.031–6.883, p = 0.043). Conclusions: A functional A1 aplasia contralateral to a distal ICA occlusion is associated with a poorer clinical outcome

Time-linearized simulation of unsteady transonic flows with shock-induced separation

During flutter analysis of a new aircraft a huge number of unsteady aerodynamic simulations is necessary in the parameter space consisting of Mach number, aeroelastic trim state, structural mode shape and frequency. For subsonic flow conditions fast potential methods like the Doublet Lattice Method can be applied. In the transonic regime unsteady flow perturbations depend on the mean flow state and CFD methods have to be employed. However, solving the nonlinear unsteady RANS equations for thousands of parameter combinations is not applicable. Hence, faster CFD methods are needed to reduce the computational costs. Assuming small time-harmonic perturbations, the RANS equations can be linearized around the steady mean solution. The latter are preferably solved in the frequency domain. This results in a large, sparse linear system for the perturbation of the fluid unknowns. In this paper an efficient time-linearized solver (LFD-TAU) is presented with special focus on 2-d external flows with strong shock-induced separation. The results are compared to small-amplitude pulse response and single-frequency RANS simulations, demonstrating good agreement over a wide frequency range. Even under pre-buffet flow conditions, showing aerodynamic resonance peaks, the resonance frequency is captured well, while the amplitudes are overestimated

Quasi-steady doublet-lattice correction for aerodynamic gust response prediction in attached and separated transonic flow

A quasi-steady doublet-lattice correction method is used to predict aerodynamic gust responses of two different configurations: a swept wing, the so-called Aerostabil wing, and a transport aircraft configuration, the NASA Common Research Model. The results of the correction method are compared to uncorrected doublet-lattice results, and to results obtained from a nonlinear computational fluid dynamics solver, the DLR TAU-Code. The correction method agrees well with time-marching results obtained by TAU in the limit of dynamically linear gust amplitudes and improves with gust length. In separated transonic flow, an oscillation of the aerodynamic gust response can be computed

Time-Linearized Analysis of Motion-Induced and Gust-Induced Airloads with the DLR TAU Code

This paper provides an overview about the time-linearized analysis of motion-induced and gust-induced airloads with the DLR flow solver TAU. Time-linearized CFD methods to compute an aircraft’s aerodynamic response to sinusoidal oscillations promise a reduced computational effort while retaining the fidelity of the RANS flow characteristics. Two approaches are presented: a system identification method which excites the nonlinear steady background flow state with a broad-band pulse signal of small amplitude resulting in the aerodynamic frequency response function, and the DLR TAU linear frequency domain (LFD) solver which solves the linearized and Fourier transformed unsteady RANS equations for the first harmonic of the aerodynamic response. Both methods are validated with forced-motion pitching oscillations of the 2-d NACA 64A010 airfoil in comparison to the response of the fully nonlinear solver. Furthermore, the pulse method and LFD method are extended for sinusoidal gust encounters

Elastic stabilisation of proximal humeral fractures with a new percutaneous angular stable fixation device (ButtonFix(®)) : a preliminary report

The ButtonFix(®) system represents a new angular stable percutaneous fixation device for stabilisation of fractures of the proximal humerus. The purpose of this study was to present a preliminary report of the radiological and clinical outcome after minimally invasive stabilisation of selected proximal humerus fractures with the ButtonFix(®)

Closed reduction and minimally invasive percutaneous fixation of proximal humerus fractures using the Humerusblock

To evaluate the results after closed reduction and percutaneous fixation of displaced fractures of the proximal humerus with the Humerusblock system