Symmetry algebra of a generalized anisotropic harmonic oscillator

It is shown that the symmetry Lie algebra of a quantum system with accidental degeneracy can be obtained by means of the Noether's theorem. The procedure is illustrated by considering a generalized anisotropic two dimensional harmonic oscillator, which can have an infinite set of states with the same energy characterized by an u(1,1) Lie algebra

Impact of adversarial examples on deep learning models for biomedical image segmentation

Deep learning models, which are increasingly being used in the field of medical image analysis, come with a major security risk, namely, their vulnerability to adversarial examples. Adversarial examples are carefully crafted samples that force machine learning models to make mistakes during testing time. These malicious samples have been shown to be highly effective in misguiding classification tasks. However, research on the influence of adversarial examples on segmentation is significantly lacking. Given that a large portion of medical imaging problems are effectively segmentation problems, we analyze the impact of adversarial examples on deep learning-based image segmentation models. Specifically, we expose the vulnerability of these models to adversarial examples by proposing the Adaptive Segmentation Mask Attack (ASMA). This novel algorithm makes it possible to craft targeted adversarial examples that come with (1) high intersection-over-union rates between the target adversarial mask and the prediction and (2) with perturbation that is, for the most part, invisible to the bare eye. We lay out experimental and visual evidence by showing results obtained for the ISIC skin lesion segmentation challenge and the problem of glaucoma optic disc segmentation. An implementation of this algorithm and additional examples can be found at https://github.com/utkuozbulak/adaptive-segmentation-mask-attack

Case Study: Diesel-Powered Loaders Compared to Hybrid Loaders in Heavy Civil Construction

With the construction industry constantly changing, the environmental impacts of greenhouses gases have become a huge concern. Many contractors are adapting and switching over to hybrid powered systems to allow for more energy saving methods for heavy equipment, an increase in productivity, and efficient construction equipment that comply with emission regulations. The goal for this paper is to analyze the feasibility of heavy civil construction companies switching over from conventional diesel-powered wheel loaders to hybrid wheel loaders. Due to the competitive and saturated market in roadwork construction, many contractors have already begun to invest into hybrid systems. This provides cost savings in fuel efficiency and operating costs over the conventional fueled loaders. Qualitative research was conducted for this report through semi-structured personal interviews with heavy equipment experts, and the usage of primary and secondary sources. Although the switch to operating with a hybrid system it will potential have a higher up-front cost, it will have fewer operating costs and environmental impacts in the future

Observation of magnetization reversal in epitaxial Gd0.67Ca0.33MnO3 thin films

High quality epitaxial thin films of Gd0.67Ca0.33MnO3 have been deposited onto (100) SrTiO3 substrates by pulsed-laser deposition. Enhanced properties in comparison with bulk samples were observed. The magnetic transition temperature (Tc) of the as-grown films is much higher than the corresponding bulk values. Most interestingly, magnetization measurements performed under small applied fields, exhibit magnetization reversals below Tc, no matter whether the film is field-cooled (FC) or zero-field-cooled (ZFC). A rapid magnetization reversal occurs at 7 K when field cooled, while as for the ZFC process the magnetization decreases gradually with increasing temperatures, taking negative values above 7 K and changing to positive values again, above 83 K. In higher magnetic fields the magnetization does not change sign. The reversal mechanism is discussed in terms of a negative exchange f-d interaction and magnetic anisotropy, this later enhanced by strain effects induced by the lattice mismatch between the film and the substrate.Comment: 16 pages, 4 figure

Probiotics in arthralgia and spondyloarthropathies in patients with inflammatory bowel disease. Prospective randomized trials are necessary

Arthralgias and spondyloarthropathies of the peripheral and axial joints are common in inflammatory bowel disease. Evidence for a strong association between these clinical manifestations and diseases of the joints has been provided by several clinical and epidemiological studies. Immunological studies have shown the presence of shared inflammatory cells both in the gut and the synovium in spondyloarthropathies. Genetic factors play a crucial role in the pathogenesis of spondyloarthropathies and inflammatory bowel disease. The role of the ubiquitous bacterial flora and pathogenic microorganisms present in the intestinal lumen may induce these joint diseases in patients with inflammatory bowel disease. In this review we will focus on the pathogenesis of spondyloarthropathies and arthralgia in patients suffering from inflammatory bowel disease. Based on preliminary clinical observations in patients with arthralgia and IBD, we put forward the hypothesis that probiotics may be helpful in the management of common extraintestinal manifestations such as arthralgia in patients with ulcerative colitis and Crohn's disease