Anterolateral Ligament Expert Group consensus paper on the management of internal rotation and instability of the anterior cruciate ligament - deficient knee

Purpose of this paper is to provide an overview of the latest research on the anterolateral ligament (ALL) and present the consensus of the ALL Expert Group on the anatomy, radiographic landmarks, biomechanics, clinical and radiographic diagnosis, lesion classification, surgical technique and clinical outcomes. A consensus on controversial subjects surrounding the ALL and anterolateral knee instability has been established based on the opinion of experts, the latest publications on the subject and an exchange of experiences during the ALL Experts Meeting (November 2015, Lyon, France). The ALL is found deep to the iliotibial band. The femoral origin is just posterior and proximal to the lateral epicondyle; the tibial attachment is 21.6 mm posterior to Gerdy's tubercle and 4-10 mm below the tibial joint line. On a lateral radiographic view the femoral origin is located in the postero-inferior quadrant and the tibial attachment is close to the centre of the proximal tibial plateau. Favourable isometry of an ALL reconstruction is seen when the femoral position is proximal and posterior to the lateral epicondyle, with the ALL being tight upon extension and lax upon flexion. The ALL can be visualised on ultrasound, or on T2-weighted coronal MRI scans with proton density fat-suppressed evaluation. The ALL injury is associated with a Segond fracture, and often occurs in conjunction with acute anterior cruciate ligament (ACL) injury. Recognition and repair of the ALL lesions should be considered to improve the control of rotational stability provided by ACL reconstruction. For high-risk patients, a combined ACL and ALL reconstruction improves rotational control and reduces the rate of re-rupture, without increased postoperative complication rates compared to ACL-only reconstruction. In conclusion this paper provides a contemporary consensus on all studied features of the ALL. The findings warrant future research in order to further test these early observations, with the ultimate goal of improving the long-term outcomes of ACL-injured patients. Level of evidence Level V-Expert opinion

Monte Carlo Analysis for a Booster Flyback Guidance System

The aim of this study is to develop and test a robust guidance strategy for use on the flyback mission of a winged launch booster. The guidance system employs a numerical Newton-Raphson restoration technique to update steering parameters, coupled with heuristic logic, to improve robustness. The guidance system uses a prediction of the final state of the launch vehicle to close the feedback loop and is therefore called “Predictive guidance”. Virtual environment and virtual vehicle models are used to simulate the booster and the environment in which it operates. The virtual booster passes the current velocity and position to the predictive guidance system at given guidance intervals. The predictive guidance system then integrates along the trajectory, using the current parameterized steering model, to determine the expected final position of the virtual booster. It compares the achieved final state to the required target state and calculates the target error. A parameterized non-linear restoration technique then determines new values for the steering parameters, to guide the virtual booster from the current state to the desired state. The final phase of the flyback mission is guided by a series of controllers, which achieve and maintain the required cruise flight conditions. Once the guidance system is operational for the nominal case, various errors are introduced in the virtual environment to test robustness. A Monte Carlo type analysis is performed to test the guidance system operation in 1000 different flight regimes, with randomly varied environmental and state parameters. The randomly varied parameters include: wind speed and direction, staging flight path angle, velocity and altitude and modelled state estimation errors. Different gravitation and atmosphere models are also used in the virtual environment and guidance computer to introduce further differences between the guidance estimate of the flight environment and the virtual flight environment. The guidance system is found to be fast enough for real-time implementation and able to achieve cruise conditions in all cases. The Monte Carlo analysis also allows for a statistical analysis to determine the mean and standard deviations for the target conditions.Matthew R. Tetlow, Michael E. Evans, Gerald M. Schneider and U.M. Schöttlehttp://pdf.aiaa.org/preview/CDReadyMASM05_666/PV2005_819.pd

Performance of a predictive guidance system for booster flyback

The aim of this study is to develop and test a robust guidance strategy for use on the flyback mission of a winged launch booster. The guidance system employs a numerical Newton-Raphson restoration technique to update steering parameters, coupled with heuristic logic, to improve robustness. The guidance system uses a prediction of the final state of the launch vehicle to close the feedback loop and is therefore called "predictive guidance".M.R. Tetlow, U.M. Schottle, M.E. Evans and G.M. Schneiderhttp://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=142674

Comparison of glideback and flyback boosters

© American Institute of Aeronautics and AstronauticsM. R. Tetlow; U. M. Schottle; G. M. Schneide

Mirror me: imitative responses in adults with autism

Dysfunctions of the human mirror neuron system have been postulated to underlie some deficits in autism spectrum disorders including poor imitative performance and impaired social skills. Using three reaction time experiments addressing mirror neuron system functions under simple and complex conditions, we examined 20 adult autism spectrum disorder participants and 20 healthy controls matched for age, gender and education. Participants performed simple finger-lifting movements in response to (1) biological finger and non-biological dot movement stimuli, (2) acoustic stimuli and (3) combined visual-acoustic stimuli with different contextual (compatible/incompatible) and temporal (simultaneous/asynchronous) relation. Mixed model analyses revealed slower reaction times in autism spectrum disorder. Both groups responded faster to biological compared to non-biological stimuli (Experiment 1) implying intact processing advantage for biological stimuli in autism spectrum disorder. In Experiment 3, both groups had similar 'interference effects' when stimuli were presented simultaneously. However, autism spectrum disorder participants had abnormally slow responses particularly when incompatible stimuli were presented consecutively. Our results suggest imitative control deficits rather than global imitative system impairments

Vertical Ascent to Geosynchronous Orbit with Constrained Thrust Angle

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