Dependences of statistical characteristics of <Emphasis Type="Italic">NmE</Emphasis> on the month of the year at middle and low latitudes under daytime geomagnetically quiet conditions at low solar activity

Month-to-month changes in the statistical characteristics of the ionospheric E layer peak electron density NmE at medium and low geomagnetic latitudes under daytime geomagnetically quiet conditions are investigated. Critical frequencies of the ionospheric E layer measured by the middle latitude ionosonde Boulder and low latitude ionosondes Huancayo and Jicamarca at low solar activity from 1957 to 2015 have been used in the conducted statistical analysis. The mathematical expectation of NmE, standard deviation of NmE from the expectation of NmE, and NmE variation coefficient have been calculated for each month of the year. The months of the formation of extrema of these statistical parameters of NmE were found.     

A simple pore water hydrogen diffusion syringe sampler

Molecular hydrogen (H(2)) is an important intermediate product and electron donor in microbial metabolism. Concentrations of dissolved H(2) are often diagnostic of the predominant terminal electron-accepting processes in ground water systems or aquatic sediments. H(2) concentrations are routinely measured in ground water monitoring wells but are rarely measured in saturated aquatic sediments due to a lack of simple and practical sampling methods. This report describes the design and development (including laboratory and field testing) of a simple, syringe-based H(2) sampler in (1) saturated, riparian sediments, (2) surface water bed sediments, and (3) packed intervals of a fractured bedrock borehole that are inaccessible by standard pumped methods.     

Modulation and symmetry changes in stellar dynamos

Stellar dynamos are governed by non-linear partial differential equations (PDEs) which admit solutions with dipole, quadrupole or mixed symmetry (i.e. with different parities). These PDEs possess periodic solutions that describe magnetic cycles, and numerical studies reveal two different types of modulation. For modulations of Type 1 there are parity changes without significant changes of amplitude, while for Type 2 there are amplitude changes without significant changes in parity. In stars like the Sun, cyclic magnetic activity is interrupted by grand minima that correspond to Type 2 modulation. Although the Sun's magnetic field has maintained dipole symmetry for almost 300 yr, there was a significant parity change at the end of the Maunder Minimum. We infer that the solar field may have flipped from dipole to quadrupole polarity (and back) after deep minima in the past and may do so again in the future. Other stars, with different masses or rotation rates, may exhibit cyclic activity with dipole, quadrupole or mixed parity. The origins of such behaviour can be understood by relating the PDE results to solutions of appropriate low-order systems of ordinary differential equations (ODEs). Type 1 modulation is reproduced in a fourth-order system while Type 2 modulation occurs in a third-order system. Here we construct a new sixth-order system that describes both types of modulation and clarifies the interactions between symmetry-breaking and modulation of activity. Solutions of these non-linear ODEs reproduce the qualitative behaviour found for the PDEs, including flipping of polarity after a prolonged grand minimum. Thus we can be confident that these patterns of behaviour are robust, and will apply to stars that are similar to the Sun.     

Hydrogen generation during the radiolysis of crystallization water in carnallite and possible consequences of this process

Newly obtained data on hydrogen generation during the radiolysis of crystallization water in carnallite from the Verkhnekamskoe salt deposit indicate that microinclusions of hydrogen and free hydrogen are generated in carnallite-bearing rocks spatially restricted to the carnallite zone of the unit of potassic salts at the deposit. The radiolysis of crystallization water in carnallite is thought to proceed under the effect of ⁴⁰K and ⁸⁷Rb. The extensive fracturing of the carnallite rocks compared to that of sylvinite- and halite-bearing ones is a consequence of radiolysis. Other consequences of this processes are analyzed.     

First-Order Inconsistencies Caused by Rogue Trajectories

A theoretical requirement of the Interaction by Exchange with the Conditional Mean (IECM) micromixing model is that the mean concentration field produced by it must be consistent with the mean concentration field produced by a traditional Lagrangian stochastic (LS) marked particle model. We examine the violation of this requirement that occurs in a coupled LS–IECM model when unrealistically high particle velocities occur. No successful strategy was found to mitigate the effects of these rogue trajectories. It is our hope that this work will provide renewed impetus for investigation into rogue trajectories and methods to eliminate them from LS models.     

Upper mantle plasticity from laboratory experiments

On the basis of two assumptions i.e. (1) plastic and anelastic behaviour of the upper mantle can be approximated by the behaviour of the dominant mineral olivine, and (2) the behaviour of natural olivine and synthetic forsterite are similar, we have investigated the flow laws and the flow microstructures of forsterite single crystals. The results obtained between 1400–1650°C and 10–100 MPa suggest a model of climb controlled creep in which the a edge dislocations are dominant. The activation energy measured in that regime is 4.7 eV, close to that of Si self-diffusion and the flow law is $\text{?}\text{?}\text{=10}{}^6\text{σ}{}^{2.6}\text{exp}\text{(?4.7}\text{eV/k}\text{T)}$, where σ is in MPa. Extrapolation of these results to the upper mantle would imply very low stresses (i.e. ?10 MPa) in the asthenosphere. However the effect of pressure and grain size are unknown and extrapolation to very low stresses is not straightforward.     

Pattern-Recognition-Verfahren in der Umweltanalytik und Ökotoxikologie: Methodische Grundlagen

Modern methods of analyses of environment yield multivariate data sets of measured objects which are used as the basis of the evaluation and interpretation of substances, differentiated effects, but also of samples or processes. The integrated evaluation and assessment of such multivariate data requires the application of mathematical-statistical methods, the method of pattern recognition being particularly suitable. Pattern recognition program systems constitute a compilation of different methods, as e.g. the multivariate linear regression, classification methods (discriminant analysis, multivariate variance analysis), cluster algorithms, multidimensional scaling, factorial analysis. A few possibilities of such pattern comparisons and identifications are represented by the example of gas chromatography and of the structure/effect analysis for the mutagenity to be expected of 117 substances.     

Kimberlite metasomatism at Murowa and Sese pipes, Zimbabwe

Metasomatism accompanying kimberlite emplacement is a worldwide phenomenon, although infrequently described or recognised. At the Cambrian-aged Murowa and Sese kimberlite clusters located within the Archean Zimbabwe Craton just north of the boundary with the Limpopo Mobile Zone in southern central Zimbabwe, the metasomatism is intense and well exposed and the processes can be readily studied. Dykes, sills and the root zones of pipes are exposed at the current erosion level. Kimberlite lithologies present are hypabyssal macrocrystic kimberlite (“HMK”), HMK breccia, and tuffisitic kimberlite breccia (“TKB”) including minor lithic tuffisitic kimberlite breccia (“LTKB”). Country rocks are 2.6 Ga Chibi and Zimbabwe granite batholiths emplaced into 2.6–2.9 Ga or earlier Archean tonalitic gneiss and greenstones. During initial metasomatism, the granites become spotted with green chlorite, needles of alkaline amphiboles (winchite, riebeckite, arfvedsonite) and pyroxenes (aegirine–augite) with minor carbonate and felts of talc. Oligoclase feldspar becomes converted to albite, extensively altered, dusted and reddened with hematite, whereas K-feldspar remains unaffected. The granites become converted to syenite through removal of quartz. More intense metasomatism at Murowa and Sese results in veins of green metasomatite which cut and disrupt the granite. Progressive disruption entrains granite blocks, breaking down the granite still further, spalling off needle-like granite slivers, and so giving rise to LTKB. This process of disruption and entrainment appears to be the manner of initial development of the pipe structure. The chemistry of the metasomatite is intermediate between granite and kimberlite. Compared to granite country rock it has markedly higher Mg, Cr, Ni, CO₂ and H₂O+, higher Ca, Mn, Nb, Sr, P, Fe³⁺/Fe²⁺ ratio, U, Co, and Cu, approximately equal TiO₂, K₂O, Na₂O, La, Ta, Rb, Zr, Zn and resultant lower SiO₂, Al₂O₃, Ga and Y. The metasomatite Na₂O/K₂O ratio is slightly higher than that of the granite. The metasomatic process is broadly analogous to fenitisation of granitic wall rock accompanying carbonatite complex emplacement. The metasomatism at Murowa and Sese was caused by fluids from the rising but confined proto-kimberlite melt penetrating into cracks and matrix of granite country rock and reacting with it. These fluids were CO₂-rich, hydrous, oxidising, enhanced in ultramafic elements and carried low levels of Na.