Numerical simulations of NMR relaxation in chalk using local Robin boundary conditions.

The interpretation of nuclear magnetic resonance (NMR) data is of interest in a number of fields. In Ögren (2014) local boundary conditions for random walk simulations of NMR relaxation in digital domains were presented. Here, we have applied those boundary conditions to large, three-dimensional (3D) porous media samples. We compared the random walk results with known solutions and then applied them to highly structured 3D domains, from images derived using synchrotron radiation CT scanning of North Sea chalk samples. As expected, there were systematic errors caused by digitalization of the pore surfaces so we quantified those errors, and by using linear local boundary conditions, we were able to significantly improve the output. We also present a technique for treating numerical data prior to input into the ESPRIT algorithm for retrieving Laplace components of time series from NMR data (commonly called T-inversion).

Microstructure and micromechanics of the heart urchin test from X-ray tomography.

The microstructure of many echinoid species has long fascinated scientists because of its high porosity and outstanding mechanical properties. We have used X-ray microtomography to examine the test of Echinocardium cordatum (heart urchin), a burrowing cousin of the more commonly known sea urchins. Three dimensional imaging demonstrates that the bulk of the test is composed of only two distinct, highly porous, fenestrated regions (stereom), in which the thickness of the struts is constant. Different degrees of porosity are achieved by varying the spacing of the struts. Drawing an analogy to vertebrate trabecular bone, where for example, human bone has a connectivity density of ≈1/mm(3), we measure up to 150,000 strut connections per mm(3). Simulations of mechanical loading using finite element calculations indicate that the test performs at very close to the optimum expected for foams, highlighting the functional link between structure and mechanical properties.

[The efficacy of health resort treatment of psoriatic arthritis at Yevpatoriya]. / Effektivnost' kurortnogo lecheniia psoriaticheskogo artrita v Evpatorii.

The authors analyze the efficacy of treatment of 162 patients suffering from psoriatic arthritis in Evpatoria health resort. The treatment modalities included brine baths, mud applications, climatotherapy, etc. Clinical cure or considerable improvement has been achieved in 21.8% of patients, improvement in 74.3%, no therapeutic effect in 3.9%. Along with alleviation of the clinical manifestations of psoriatic arthritis, a number of immunological and biochemical parameters (albumin, lysozyme, IgM levels) have shown a tendency to normalization. The combined health resort therapy is an effective means of the after-care of psoriatic arthritis.