Emergence of Compositional Representations in Restricted Boltzmann Machines

Extracting automatically the complex set of features composing real high-dimensional data is crucial for achieving high performance in machine-learning tasks. Restricted Boltzmann machines (RBM) are empirically known to be efficient for this purpose, and to be able to generate distributed and graded representations of the data. We characterize the structural conditions (sparsity of the weights, low effective temperature, nonlinearities in the activation functions of hidden units, and adaptation of fields maintaining the activity in the visible layer) allowing RBM to operate in such a compositional phase. Evidence is provided by the replica analysis of an adequate statistical ensemble of random RBMs and by RBM trained on the handwritten digits data set MNIST.

Clinical evaluation of the Carisolv chemomechanical caries removal technique according to the site/stage concept, a revised caries classification system

The objective of the present study was to assess the efficiency and benefit of a chemomechanical system for carious dentin removal, Carisolv, in general practice. A revised caries classification, the site/stage concept, was used to describe the clinical situations of all carious lesions treated. The study was performed by 12 investigators, and 120 carious lesions were treated with Carisolv. Sixty percent of the cases were treated without anaesthesia, and we found a significant correlation between chemomechanical treatment without anaesthesia and absence of pain ( P=0.01). In 78.3% of the cases, carious dentin was totally removed with Carisolv, and in 21.7%, the dentin treatment was completed by drilling. In cases performed with Carisolv alone, the time required to remove carious dentin was 11.1+/-9.51 min (mean+/-SD). Treatment time was equivalent for all sites and increased significantly with each successive stage of lesion progression ( P<0.001). In 82.5% of cases, the clinicians were satisfied with Carisolv, and in 99.2%, so were the patients. We conclude that, using clinical examination methods, Carisolv seems to remove carious dentin at all sites and stages of carious lesions but must be made more efficient for use in general practice.

[Developmental anomaly of the hyoid bone: an unusual cause of dysphagia]

We report the case of a hyoid syndrome caused by a developmental anomaly of the second branchial cleft, presenting at adult age by dysphagia without any abnormality detected at the barium swallow and at naso-pharyngeal endoscopy, first examinations to perform in case of dysphagia. The MRI findings of this anomaly showed a hyperintense well-limited vallecular mass syndrome. The diagnosis of hyoid bone anomaly was established at spiral CT with 3D reconstructions showing an incurvated and elongated lesser cornua causing persistant impingement on the lateral wall of the oropharynx. CT scan performed during Valsalva manoeuver showed the persistance of the compression during pharyngeal insufflation.

[Adductor muscle pyomyositis simulating acute appendicitis: CT and MR imaging findings]

Pyomyositis is a primary bacterial infection of skeletal muscle. This infection tends to occur in the large muscles of the lower extremity. Pyomyositis of the proximal muscles of the thigh can simulate acute abdominal disease. Early diagnosis improves the outcome. Delayed diagnosis may lead to septicemia and shock. We report the CT and MRI findings in a patient with pyomyositis of the proximal muscles of the thigh.

[Hajdu-Cheney syndrome: an unusual cause of acro-osteolysis]

We report a case of Hajdu-Cheney syndrome. This cranioskeletal dysplasia is characterized by band-like acro-osteolysis of the tufts middle thirds. Differential diagnosis of band-like acro-osteolysis are discussed.