10 research outputs found
Compressed sensing electron tomography using adaptive dictionaries: a simulation study
Electron tomography (ET) is an increasingly important technique for examining the three-dimensional morphologies of nanostructures. ET involves the acquisition of a set of 2D projection images to be reconstructed into a volumetric image by solving an inverse problem. However, due to limitations in the acquisition process this inverse problem is considered ill-posed (i.e., no unique solution exists). Furthermore reconstruction usually suffers from missing wedge artifacts (e.g., star, fan, blurring, and elongation artifacts). Compressed sensing (CS) has recently been applied to ET and showed promising results for reducing missing wedge artifacts caused by limited angle sampling. CS uses a nonlinear reconstruction algorithm that employs image sparsity as a priori knowledge to improve the accuracy of density reconstruction from a relatively small number of projections compared to other reconstruction techniques. However, The performance of CS recovery depends heavily on the degree of sparsity of the reconstructed image in the selected transform domain. Prespecified transformations such as spatial gradients provide sparse image representation, while synthesising the sparsifying transform based on the properties of the particular specimen may give even sparser results and can extend the application of CS to specimens that can not be sparsely represented with other transforms such as Total variation (TV). In this work, we show that CS reconstruction in ET can be significantly improved by tailoring the sparsity representation using a sparse dictionary learning principle
Impulsiveness in Alcohol Addiction and Pathological Gambling
Numerous conducted studies, as well as the daily clinical experience, proves the importance of the role that impulsiveness plays in the clinical course and the treatment response in both psychoactive substance addictions, such as alcohol use disorder and behavioral addictions, such as gambling addiction. In the daily practice, impulsiveness as a personality trait is observed either in the context of a determining, i.e. causing factor in the personality development or as a result of a developed addiction. Certain types of impulsiveness are more often present in certain types of addicts and their detection enables us to make a more precise diagnosis and sub-classification as well as a more adequate adaptation of the treatment protocol. According to the studies so far, the occurrence of impulsiveness significantly affects the occurrence of relapse in treated addicts. To a large extent it also determines the range of the treatment response to the applied treatment procedures. The objective of this review was to point out the specific features of the prevalence of certain impulsiveness elements in psychoactive substance addicts, such as alcohol addicts, and of behavioral addicts, such as gambling addicts, and to additionally emphasize their clinical, diagnostic, treatment and prognostic value
Morphology and local electrical properties of PTB7:PC71BM blends
The power conversion efficiency of single layer organic solar cells can approach 10% with blends such as the polymer PTB7 and the fullerene derivative PC71BM. Here the detailed structure of PTB7:PC71BM blends deposited with and without addition of diiodooctane is studied by transmission electron microscopy and scanning probe microscopy. The details of bulk structure, such as the thickness of the layer covering fullerene domains and the grain structure of the film are examined. We find that fullerene-rich domains can be near the surface of the film or buried deeper, near the substrate. The local electrical properties of these blends are studied by conductive atomic force microscopy for different configurations of electrodes. Different power conversion efficiencies of blends with and without diiodooctane are explained in terms of local photoconductive properties