MHD from a Microscopic Concept and Onset of Turbulence in Hartmann Flow

We derive higher order magneto-hydrodynamic （MHD） equations from a microscopic picture using pro-jection and perturbation formalism. In an application to Hartmann flow we find velocity profiles flattening towards the center at the onset of turbulence in hydrodynamic limit. Comparison with the system under the effect of a uniform magnetic field yields difference in the onset of turbulence consistent with observations, showing that the presence of magnetic field inhibits onset of instability or turbulence. The laminar-turbulent transition is demonstrated in a phase transition plot of the development in time of the relative average velocities vs. Reynolds number showing a sharp increase of the relative average velocity at the transition point as determined by the critical Reynolds number.

Ecological Research of Former Brown-coal Quarry-the Most Lake in the Czech Republic

The presented article discusses the results of survey of the Most lake, which was created within hydric recultivation of the site of the former brown-coal mine Most Lezaky in northern Bohemia in the Czech Republic. The survey discovered plants which belong to ruderal, wetland, halophilic and xerothermal species based on their life strategy. The discovered endangered species include Carex secalina, Schoenoplectus tabaernemontani, Salsola call subsp. Rosacea and Tetragonolobus maritimus. A total of 350 species of vascular plants were discovered in the study area. During the monitoring, a total of 146 bird species were discovered. The monitored location can be currently considered as a significant gathering place namely for aquatic and wetland bird species during the winter period and the migration period （e.g., Tachybaptus ruficollis, Podiceps cristatus, Anser anser, Anas platyrhynchos, Anas strepera, Fulica atra and various species of Larus sp.） and as a significant area of occurrence of relatively rare species bound to anthropogenetically disturbed areas of mining and post-mining landscape （e.g., Anthus campestris, Anthus pratensis, Motacillaflava, Oenanthe oenanthe, Saxicola rubetra and Saxicola torquata）. Within the monitoring of the water quality, the saprobic index values （S） ranged in 2013 between 1.62 and 1.92.

Study on the structure and composition of aortic valve calcific deposits:Etiological aspects

The structures and chemical compositions of valve calcific deposits were investigated. The deposits was chosen arbitrarily and subjected to chemical analysis, observation with scanning microscope, semi-quantitative determination of Ca, Mg, Na, K, P and C elements by energy dispersive X-ray, X-ray diffraction and Fourier transform infrared spectroscopy carried out. These deposits were found to have non-uniform internal structures composed of layers of a structureless aspidinic inorganic material, substantial amounts of voluminous organic material and in a few samples small spheres were also present. Two groups of deposits with distinctly different chemical compositions were identified: one group with a low Ca/P molar ratio (1.59) and the other group with a high (1.82) Ca/P molar ratio. The deposits belonging to the group with a low Ca/P molar ratio contain higher concentration of magnesium and consist of increased amount of amorphous calcium phosphate. The deposits with a high Ca/P molar ratio contain low concentration of magnesium and consist predominantly of carbonated hydroxyapatite. The inorganic material was identified as a poorly crystalline carbonate hydroxyapatite containing molecular water of the average formula Ca9.1Mg0.4(Na,K)(PO4)5.8(CO3)0.3(OH)2. The actual chemical composition of the apatitic solid phase varies not only from deposit to deposit but also within the same deposit. The non-uniform internal structure of the deposits, the occasional presence of spherical particles and the variable point composition of the individual deposits indicate that their formation did not proceed under more or less constant conditions.

Pipe Flow and Wall Turbulence Using a Modified Navier-Stokes Equation

We use a derived incompressible modified Navier-Stokes equation to model pipe flow and wall turbulence. We reproduce the observed flattened paraboloid velocity profiles of turbulence that cannot be obtained directly using standard incompressible Navier-Stokes equation. The solutions found are in harmony with multi-valued velocity fields as a definition of turbulence. Repeating the procedure for the flow of turbulent fluid between two parallel flat plates we find similar flattened velocity profiles. We extend the analysis to the turbulent flow along a single wall and compare the results with experimental data and the established controversial yon Karman logarithmic law of the wall.