Computation of canting errors in heliostats by flux map fitting: experimental assessment.

In solar tower plants, thousands of heliostats reflect sunlight into a central receiver. Heliostats consist of a subset of mirrors called facets that must be perfectly oriented (i.e., canted) to concentrate as much solar radiation as possible. This study presents and validates the so-called flux map fitting technique to detect and correct canting errors. The computed distributions were matched to a series of images through an optimization algorithm. According to the sensitivity analysis, three images spread along a single day provide sufficient information for the algorithm to succeed. Using this methodology, four heliostats at the THEMIS research facility were recanted, thereby substantially increasing the optical quality in three of them. The procedure to infer the heliostat aimpoint was assessed.

Different phenotypes in dermatomyositis associated with anti-MDA5 antibody: Study of 121 cases.

OBJECTIVES: The predominance of extramuscular manifestations (e.g., skin rash, arthralgia, interstitial lung disease [ILD]) as well as the low frequency of muscle signs in anti-melanoma differentiation-associated gene 5 antibody-positive (anti-MDA5+) dermatomyositis caused us to question the term myositis-specific antibody for the anti-MDA5 antibody, as well as the homogeneity of the disease. METHODS: To characterize the anti-MDA5+ phenotype, an unsupervised analysis was performed on anti-MDA5+ patients (n = 83/121) and compared to a group of patients with myositis without anti-MDA5 antibody (anti-MDA5-; n = 190/201) based on selected variables, collected retrospectively, without any missing data. RESULTS: Within anti-MDA5+ patients (n = 83), 3 subgroups were identified. One group (18.1%) corresponded to patients with a rapidly progressive ILD (93.3%; p < 0.0001 across all) and a very high mortality rate. The second subgroup (55.4%) corresponded to patients with pure dermato-rheumatologic symptoms (arthralgia; 82.6%; p < 0.01) and a good prognosis. The third corresponded to patients, mainly male (72.7%; p < 0.0001), with severe skin vasculopathy, frequent signs of myositis (proximal weakness: 68.2%; p < 0.0001), and an intermediate prognosis. Raynaud phenomenon, arthralgia/arthritis, and sex permit the cluster appurtenance (83.3% correct estimation). Nevertheless, an unsupervised analysis confirmed that anti-MDA5 antibody delineates an independent group of patients (e.g., dermatomyositis skin rash, skin ulcers, calcinosis, mechanic's hands, ILD, arthralgia/arthritis, and high mortality rate) distinct from anti-MDA5- patients with myositis. CONCLUSION: Anti-MDA5+ patients have a systemic syndrome distinct from other patients with myositis. Three subgroups with different prognosis exist.