Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

A practical clinical kinematic model for the upper limbs

A novel clinically practical upper limb model is introduced that has been developed through clinical use in children and adults with neurological conditions to guide surgery to the elbow and wrist. This model has a minimal marker set, minimal virtual markers, and no functional joint centres to minimise the demands on the patient and duration of data collection. The model calculates forearm supination independently from the humerus segment, eliminating any errors introduced by poor modelling of the shoulder joint centre. Supination is calculated by defining the forearm segment twice, from the distal and proximal ends: first, using the ulna and radial wrist markers as a segment defining line and second using the medial and lateral elbow markers as a segment defining line. This is comparable to the clinical measurement of supination utilising a goniometer and enables a reduced marker set, with only the elbow, wrist, and hand markers to be applied when only the wrist and forearm angles are of interest. A sensitivity analysis of the calculated elbow flexion–extension angles to the position of the glenohumeral joint centre is performed on one healthy female subject, aged 20 years, during elbow flexion and a forward reaching task. A comparison of the supination angles calculated utilising the novel technique compared to the rotation between the humeral and forearm segments is also given. All angles are compared to a published kinematic model that follows the recommendations of the International Society of Biomechanics. </jats:p