Current status of turbulent dynamo theory: From large-scale to small-scale dynamos

Several recent advances in turbulent dynamo theory are reviewed. High resolution simulations of small-scale and large-scale dynamo action in periodic domains are compared with each other and contrasted with similar results at low magnetic Prandtl numbers. It is argued that all the different cases show similarities at intermediate length scales. On the other hand, in the presence of helicity of the turbulence, power develops on large scales, which is not present in non-helical small-scale turbulent dynamos. At small length scales, differences occur in connection with the dissipation cutoff scales associated with the respective value of the magnetic Prandtl number. These differences are found to be independent of whether or not there is large-scale dynamo action. However, large-scale dynamos in homogeneous systems are shown to suffer from resistive slow-down even at intermediate length scales. The results from simulations are connected to mean field theory and its applications. Recent work on helicity fluxes to alleviate large-scale dynamo quenching, shear dynamos, nonlocal effects and magnetic structures from strong density stratification are highlighted. Several insights which arise from analytic considerations of small-scale dynamos are discussed.Comment: 36 pages, 11 figures, Spa. Sci. Rev., submitted to the special issue "Magnetism in the Universe" (ed. A. Balogh

Complex approach to the organization of external information flows of tourism enterprise

The aim of the article. The aim of the article is to provide the basis of the complex approach to the organization of external information flows at tourism enterprises in order to improve the management of these information flows. The results of the analysis. The complex approach of improvement of the information flows management at tourism enterprises basing on the complex of information signals and organization of feedback between consumers and tourism enterprises is proposed. Application of the theory of market signals (signaling) for implementation of the complex approach is substantiated by the fact that an enterprise should generate and extend external outgoing information flows that would contribute to the provision of additional opportunities for the increase tourism products and services output, establishment of partnership and customers attraction. Informational signals as external information flows and activation of informational signaling ensure the informational connection between customers and tourism enterprises in order to stimulate the demand on the services of tourism enterprises and accordingly, their stable competitive position in the market; consideration and formation of demand, as the customers, which are maximum informed on the opportunities of tourism enterprises and the components of an tourism product, may describe their needs in the most accurate way. However, the usage of particular informational signals does not give such opportunities to a tourism enterprise. The necessity to use the complex of informational signals by tourism enterprises was demonstrated through the game theory. If a tourism enterprise does not perform informational signaling, then the sales of tourism products become complicated. The probability of attraction of loyal customers (in accordance to the given goal) is not significant, as the choice of a tourism enterprise by a customer has a random character. Therefore, a customer attends another tourism enterprise next time. Receiving informational signals from particular tourism enterprise, a customer does not still obtain the expected result, because the person will look for another enterprise even being served in particular tourism enterprise. Focusing on a price as an informational signal, a tourism enterprise may not obtain the expected result, as a high price may be considered as the negative outcome by the customers. Therefore, they may refuse tourism services. Application of the system of informational signals enables the tourism enterprises to explain probable growth of a price to the customers by quality improvement. Price reduction may ensure a maximum benefit to the tourism enterprises if the number of their customers increases due to the system of informational signals. Conclusions and directions of further researches. The majority of tourism enterprises use particular informational signals to some extent, but they do not realize the contribution of these signals to the economic outcomes. The offered approach to the organization of external information flows of tourism enterprises ensures high demand on tourism products and accordingly contributes to the growth of profit and economic efficiency. It is considered as beneficial to direct further researches at the exploitation of the Internet-technologies to improve the management of input external information flows

Detailed study of post-Chernobyl Cs-137 redistribution in the soils of a small agricultural catchment (Tula region, Russia)

© 2020 Elsevier Ltd A detailed study of 137Cs redistribution was conducted within a small agricultural catchment in the highly contaminated Plavsk radioactive hotspot in the Tula region of Central Russia, 32 years after the Chernobyl nuclear power plant (NPP) accident, which occurred on April 26, 1986. Although more than three decades have passed since the Chernobyl NPP incident, 137Cs contamination is high. The 137Cs inventory varies from 67 to 306 kBq·m−2, which is 2–6 times higher than the radiation safety standard; however, the soils remain suitable for crop cultivation. The initial 137Cs fallout within the Plavsk radioactive hotspot was extremely heterogeneous, with a trend of decreasing 137Cs inventories from the NW to the SE directions within the studied territory. Contemporary 137Cs inventories are also very heterogeneous in the studied catchment. However, the trend of the initial 137Cs fallout does not appear in the contemporary 137Cs inventories on the slopes. Two methods of interpolation (expert-visual and automatic) were used to calculate the 137Cs budget, revealing high similarity in their 137Cs loss estimates; however, a large discrepancy was observed in their 137Cs gain estimates. A detailed analysis of 137Cs redistribution revealed the importance of hollows and “plow ramparts” (positive topographic forms on the boundaries of cultivated fields) in the transport and deposition of sediments. A quarter of the total 137Cs gain was deposited within the arable land, whereas a quarter was deposited within the non-plowing sides of the dry valley; the other half was deposited in the valley bottom. About 7–8 × 106 kBq of the 137Cs inventory flowed out of the catchment area, which was only about 2% of the 137Cs fallout after the Chernobyl NPP accident. About 89% of the total 137Cs reserve is concentrated in the top (0–25 cm) layer of soils, regardless of land use or location within the catchment

Genetic variation in honey bee (Apis mellifera L.) populations from Bulgaria [Zmiennosc Genetyczna w populacjach pszcoly miodnj(Apis mellifera L.)w Bulagartoii]

Genetic variation of honey bee populations from 9 different locations of Bulgaria was studied using 4 enzymic systems (MDH, ME, EST and ALP) corresponding to 4 genetic loci and PCR- RFLP's analysis of 16s rDNA, COI, and ND5 gene segments of mtDNA. Allozyme analysis revealed that all loci were polymorphic in almost all studied populations. The observed heterozygosity was found to range from 0.146 to 0.258, and Nei's genetic distance between 0.006 and 0.057 among the populations. Bulgarian honey bees are clustered into three groups in neighbor-joining and UPGMA dendrograms. The Pomorie and Slivovik populations are in a separate clade while all other populations are grouped together. The mtDNA analyses revealed no variation in the Bulgarian honey bees. A comparison was made of the results of similar analyses on honey bees from the neighboring countries of Greece and Turkey. The results showed that honey bee populations from Bulgaria and Greece considered to belong to A. m. macedonica subspecies are discriminating, which means the bees show differences

Systematic analysis of hyperpolarizationactivated and cyclic nucleotide-gated (HCN) channels in photoreceptors and bipolar cells of the rat retina

SIGLEAvailable from TIB Hannover: RA 831(4102) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

<i>Tundrisphaera lichenicola</i> gen. nov., sp. nov., a psychrotolerant representative of the family <i>Isosphaeraceae</i> from lichen-dominated tundra soils

Two strains of aerobic, budding, pink-pigmented bacteria, P12T and P515, were isolated from a lichen-dominated peatland and a forested tundra soil of north-western Siberia, respectively. Cells of these isolates were represented by non-motile spheres that occurred singly or were arranged in short chains and aggregates. While growing on solid media, cells of strains P12T and P515 attached to the surface by means of holdfast-like appendages. These isolates were mildly acidophilic (optimum growth at pH 5.5–6.0), psychrotolerant bacteria, which displayed tolerance of low temperatures (4–15 °C), grew optimally at 15–22 °C and did not grow at temperatures above 28 °C. The preferred growth substrates were sugars and some heteropolysaccharides. The major fatty acids were C18 : 1ω9c, C16 : 0 and C14 : 0. Trimethylornithine lipid was the major polar lipid. The only quinone was MK-6, and the G+C content of the DNA was 61.2–62.2 mol%. Strains P12T and P515 possessed identical 16S rRNA gene sequences, which affiliated them with the family Isosphaeraceae , order Planctomycetales , and these displayed the highest similarity (93–94 %) to 16S rRNA gene sequences from members of the genus Singulisphaera . However, the signature fatty acid of species of the genus Singulisphaera , i.e. C18 : 2 ω6c,12c, was absent in cells of strains P12T and P515. They also differed from members of the genus Singulisphaera by substrate utilization pattern and a number of physiological characteristics. Based on these data, the novel isolates should be considered as representing a novel genus and species of planctomycetes, for which the name Tundrisphaera lichenicola gen. nov., sp. nov, is proposed. The type strain is P12T (=LMG 29571T=VKM B-3044T)

<i>Planctomicrobium piriforme</i> gen. nov., sp. nov., a stalked planctomycete from a littoral wetland of a boreal lake

An aerobic, budding, non-pigmented and rosette-forming bacterium was isolated from a littoral wetland of a boreal lake located in Valaam Island, northern Russia, and designated strain P3T.Ellipsoidal to pear-shaped cells of this bacterium were covered with crateriform pits and possessed stalks suggesting a planctomycete morphotype. 16S rRNA gene sequence analysis confirmed that strain P3T was a member of the order Planctomycetales and belonged to a phylogenetic lineage defined by the genus Planctomyces, with 89 and 86% sequence similarity to Planctomyces brasiliensis and Planctomyces maris, respectively. Strain P3T was a mildly acidophilic, mesophilic organism capable of growth at pH values between pH 4.2 and 7.1 (with an optimum at pH 6.0–6.5) and at temperatures between 10 and 30 o C (optimum at 20–28 o C).Most sugars, a number of polysaccharides and several organic acids were the preferred growthsubstrates. Compared with Planctomyces brasiliensis and Planctomyces maris, which require NaCl for growth, strain P3T was salt-sensitive and did not develop at NaCl concentrations above 0.5% (w/v). The major fatty acids were C16 : 0 and C16 : 1w7c; the cells also contained significant amounts of C18 : 1w7c and C18 : 0. The major intact polar lipids were diacylglycerol-O-(N,N,Ntrimethyl)homoserine (DGTS) lipids; the major neutral lipids were long-chain 1,(w-1)-diols andC31 : 9 hydrocarbon. The quinone was MK-6, and the G+C content of the DNA was 59.0 mol%.Strain P3T differed from Planctomyces brasiliensis and Planctomyces maris by cell morphology,substrate utilization pattern and a number of physiological characteristics. Based on these data,the novel isolate should be considered as representing a novel genus and species ofplanctomycetes, for which the name Planctomicrobium piriforme gen. nov., sp. nov., is proposed. The type strain is P3T (=DSM 26348T=VKM B-2887T)

Ca(2+) signalling in human proximal tubular epithelial cells deficient for cystinosin

Nephropathic cystinosis is an autosomal recessive lysosomal storage disorder caused by loss-of-function mutations in the CTNS gene coding for the lysosomal cystine transporter, cystinosin. Recent studies have demonstrated that, apart from cystine accumulation in the lysosomes, cystinosin-deficient cells, especially renal proximal tubular epithelial cells are characterized by abnormal vesicle trafficking and endocytosis, possible lysosomal dysfunction and perturbed intracellular signalling cascades. It is therefore possible that Ca(2+) signalling is disturbed in cystinosis, as it has been demonstrated for other disorders associated with lysosomal dysfunction, such as Gaucher, Niemann-Pick type C and Alzheimer's diseases. In this study we investigated ATP-induced, IP3-induced and lysosomal Ca(2+) release in human proximal tubular epithelial cells derived from control and cystinotic patients. No major dysregulation of intracellular Ca(2+) dynamics was found, although ATP-induced Ca(2+) release appeared slightly sensitized in cystinotic cells compared to control cells. Hence, these subtle changes in Ca(2+) signals elicited by agonists may contribute to the pathogenesis of the disease