Estimates of the local parameters of plasma density fluctuations by reflectometry measurements

The question is considered of how to estimate the parameters of local plasma density fluctuations from reflectometry measurements made by probing the plasma with an extraordinary electromagnetic wave. In the geometrical-optics approximation, a formula is derived that relates the fluctuation amplitude of the phase of the reflected signal to the amplitude of local plasma density fluctuations and the range of its applicability is considered. The spectral sensitivity of reflectometry measurements in a reflection region of finite dimensions to poloidal perturbations with wavenumbers k _⊥ ? k ₀ is estimated by the phase-screen method, and the expressions obtained are compared with the results of numerical simulations. Based on the relationships derived, an algorithm is proposed for recovering the amplitude of the local plasma density fluctuations from the fluctuations in the reflected reflectometer signal. The results obtained are compared with the results of the full-wave simulations of the reflection of microwaves from a turbulent plasma. Finally, an example is given of how to recover the data on the amplitude of the local plasma density fluctuations in the T-10 tokamak plasma.     

Investigation of the possibility of using correlation reflectometry to determine the parameters of small-scale turbulence in the core of a tokamak plasma

Results are reported from investigating the possibility of using reflectometry to determine the parameters of small-scale turbulence in the core of a tokamak plasma. In particular, the extent to which the reflectometric measurements are local is estimated. Experimental data from reflectometric measurements in the gradient zone, as well as the cross spectra and radial correlation functions, are presented. A turbulence model is constructed that yields spectral, statistical, and correlation turbulent plasma properties close to the measured ones. The model is used to simulate the propagation of electromagnetic radiation in a turbulent plasma.     

Effect of NAD+-dependent formate dehydrogenase on anaerobic respiration of Shewanella oneidensis MR-1

An expression plasmid was constructed in order to carry out heterologous expression of the gene of the NAD⁺-dependent formate dehydrogenase (FDH) from methylotrophic bacterium Moraxella sp. in the cells of Shewanella oneidensis MR-1 under aerobic and anaerobic conditions. In both modes of cell cultivation, recombinant FDH activity was revealed in the cell lysate of the transformants. In the medium with la? tate as a carbon source, the rate of anaerobic respiration determined as the rate of conversion of fumarate (the electron acceptor) to succinate was higher in the transformant with recombinant FDH. Anaerobic cultivation of the FDH-containing transformant of S. oneidensis MR-1 in a microbial fuel cell (MFC) revealed increased current density.     

State of the antioxidant enzyme complex in tissues of the Black Sea mollusc <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> under natural oxidative stress

The state of the antioxidant (AO) system (AOS) and the content of products of lipid peroxidation (LPO) in hepatopancreas, gill, and foot of the Black Sea mollusc Mytilus galloprovincialis Lam. were studied in norm and under conditions of natural oxidative stress (spawning). It has been established that under conditions of spawning, the AO-protection of hepatopancreas cells is predominantly oriented to inactivation of high concentrations of peroxide compounds with participation of glutathione peroxidase and catalase. In the foot tissue, on the contrary, the main role in AO-processes is played by enzymatic inhibition of superoxide anion radical with aid of superoxide dismutase. The highest level of oxidative stress in the spawning state is revealed in the mollusc gill, which is indicated by the maximal increase of the content of TBA (thiobarbituric acid)-active products.     

Construction of Templates for Sequencing Extended DNA Fragments

A rapid and convenient method was proposed for constructing insertional mutants in the sequencing of extended DNA fragments. The gist is insertion of an antibiotic resistance gene in plasmid DNA digested with DNase I. DNase I provides for a uniform distribution of insertion sites along the plasmid, and the background is low owing to antibiotic-based selection. The method requires neither high quality nor large amounts of plasmid DNA (which is especially important with low-copied plasmids), yields the results independent of the plasmid nucleotide sequence, and allows highly accurate analysis and ordering of the insertional mutants.     

An asymmetric approach to preserve common intervals while sorting by reversals

Background  

The reversal distance and optimal sequences of reversals to transform a genome into another are useful tools to analyse evolutionary scenarios. However, the number of sequences is huge and some additional criteria should be used to obtain a more accurate analysis. One strategy is searching for sequences that respect constraints, such as the common intervals (clusters of co-localised genes). Another approach is to explore the whole space of sorting sequences, eventually grouping them into classes of equivalence. Recently both strategies started to be put together, to restrain the space to the sequences that respect constraints. In particular an algorithm has been proposed to list classes whose sorting sequences do not break the common intervals detected between the two inital genomes A and B. This approach may reduce the space of sequences and is symmetric (the result of the analysis sorting A into B can be obtained from the analysis sorting B into A).     

Study of the mitotic and meiotic chromosomes of sotol (<i>Dasylirion cedrosanum</i> Trel.)

The genus Dasylirion is a group of plants typically present in the Chihuahuan Desert, perennial, with a dioecious sexual behavior and commonly called sotoles. This genus has been little studied from the biological point of view, and the bases of its reproductive response remain unknown. In this work we studied the chromosome number and meiotic response of Dasylirion cedrosanum in the county of Saltillo, Coahuila, located at the North East of Mexico. For the preparation of mitotic chromosomes, we used a technique based on enzymatic treatment with pectolyase and cellulase, as well as staining with acetocarmin dye. For the study of meiosis, male flower buds were collected, fixed and stained for analysis with the same dye. As a result, the gametic (n = x = 19) and somatic chromosome (2n = 38) numbers of D. cedrosanum are reported for the first time, being consistent with previous findings in other Dasylirion species, which points to a constant ploidy level across the genus. Variation was observed in the morphology and size of the somatic chromosomes, with types ranging from submetacentric to subtelocentric, and sizes oscillating in a range of 4.43 µm, with an average total length of 112.38 µm for the diploid chromosome complement. This shows that the chromosome complement of D. cedrosanom would belong to a 3B classification of Stebins, with a medium variation between chromosome lengths and low chromosome asymmetry. This variation indicates the feasibility of constructing a chromosome ideotype for this species. The meiotic chromosome pairing showed a chromosome behavior consistent with a disomic inheritance characteristic of a diploid species, with prevalence of ring and chain bivalents, typically without pairing abnormalities. Bivalent configurations in all cases were symmetrical.The normal and symmetrical meiotic pairing indicates a balanced production of gametes, and suggests the absence of heteromorphic sex determination.