415 research outputs found
Trends of the major porin gene (ompF) evolution
OmpF is one of the major general porins of Enterobacteriaceae that belongs to the first line of bacterial defense and interactions with the biotic as well as abiotic environments. Porins are surface exposed and their structures strongly reflect the history of multiple interactions with the environmental challenges. Unfortunately, little is known on diversity of porin genes of Enterobacteriaceae and the genus Yersinia especially. We analyzed the sequences of the ompF gene from 73 Yersinia strains covering 14 known species. The phylogenetic analysis placed most of the Yersinia strains in the same line assigned by 16S rDNA-gyrB tree. Very high congruence in the tree topologies was observed for Y. enterocolitica, Y. kristensenii, Y. ruckeri, indicating that intragenic recombination in these species had no effect on the ompF gene. A significant level of intra- and interspecies recombination was found for Y. aleksiciae, Y. intermedia and Y. mollaretii. Our analysis shows that the ompF gene of Yersinia has evolved with nonrandom mutational rate under purifying selection. However, several surface loops in the OmpF porin contain positively selected sites, which very likely reflect adaptive diversification Yersinia to their ecological niches. To our knowledge, this is a first investigation of diversity of the porin gene covering the whole genus of the family Enterobacteriaceae. This study demonstrates that recombination and positive selection both contribute to evolution of ompF, but the relative contribution of these evolutionary forces are different among Yersinia species
Quantization of the Riemann Zeta-Function and Cosmology
Quantization of the Riemann zeta-function is proposed. We treat the Riemann
zeta-function as a symbol of a pseudodifferential operator and study the
corresponding classical and quantum field theories. This approach is motivated
by the theory of p-adic strings and by recent works on stringy cosmological
models. We show that the Lagrangian for the zeta-function field is equivalent
to the sum of the Klein-Gordon Lagrangians with masses defined by the zeros of
the Riemann zeta-function. Quantization of the mathematics of Fermat-Wiles and
the Langlands program is indicated. The Beilinson conjectures on the values of
L-functions of motives are interpreted as dealing with the cosmological
constant problem. Possible cosmological applications of the zeta-function field
theory are discussed.Comment: 14 pages, corrected typos, references and comments adde
Next stage of search for 2K(2)-capture of Kr
A technique to search for 2K-capture of Kr with large low-background
proportional counter filled with an enriched in Kr up to 99.8% sample of
Krypton at a pressure of 4.51 is described in this paper. The results of first
measurements are presented. Analysis of data collected during 159 hours yielded
new limit to the half-life of Kr with regard to 2K-capture
(T yr (90% C.L.)). Sensitivity of the facility to the
process for one year of measurement was evaluated to be
yr (90% C.L.).Comment: 4 pages, 5 figures; talk at the NANP'05 Conference; submitted to
Phys. At. Nuc
Review of the some specific features of the detecting of heavy recoils
In this paper, we present the results of the first beam tests of the
detection system at the focal plane of the Dubna Gas-Filled Recoil Separator-2
(DGFRS-2), which receives beams from the DC-280 FLNR cyclotron. The high beam
intensity of Ca heavy ions from the cyclotron enables us to
obtain a number of superheavy recoils sufficient to compare both the measured
and calculated spectra of superheavy recoils implanted into a silicon detector.
A real-time algorithm to search for an Evaporation Residue (ER) --
correlated sequences is described in brief. It should be noted that the DGFRS-2
spectrometer operates in conjunction with the 48x128 strip DSSD (Double-sided
Silicon Strip Detector; 48x226 mm2) detector and a low-pressure pentane-filled
gaseous detector (1.2 Torr; 80x230 mm). A block-diagram of the spectrometer
and the event format are also presented. Special attention is paid to the
response of a low-pressure pentane-filled DeltaE multiwire proportional chamber
for recoils of Fl, synthesized in the Pu+Ca Fl +3n
complete fusion nuclear reaction. Some actual parameters of the detection
system have also been extracted from Yb + Ca, Th +
Ca, Am + Ca, U + Ca reactions. The effect
of neighbor strip charge sharing for the ohmic side of the DSSD detector is
also under consideration.Comment: 18 page
Особливості явища імунодефіциту в стійкості озимої пшениці до шкідників
Decrease in a winter wheat immunity to pests owing to various mutations, which caused by application of insecticide Bi–58 (new), is established.Установлено снижение иммунитета растений озимой пшеницы к вредителям вследствие различных мутаций, вызванных использованием инсектицида Би-58 (новый).Встановлено зниження імунітету рослин озимої пшениці до шкідників внаслідок різних мутацій, викликаних використанням інсектициду Бі-58 (новий)
Види імунодефіциту рослин до шкідників
The system conception of the winter wheat’s immunodeficiency to vermin is proposed on the basis of the experimental data.На основе экспериментальных данных получено системное представление о видах иммунодефицита растений озимой пшеницы к вредителям.На основі експериментальних даних отримано системне уявлення про види імунодефіциту рослин озимої пшениці до шкідників.
Elliptic operators on manifolds with singularities and K-homology
It is well known that elliptic operators on a smooth compact manifold are
classified by K-homology. We prove that a similar classification is also valid
for manifolds with simplest singularities: isolated conical points and fibered
boundary. The main ingredients of the proof of these results are: an analog of
the Atiyah-Singer difference construction in the noncommutative case and an
analog of Poincare isomorphism in K-theory for our singular manifolds.
As applications we give a formula in topological terms for the obstruction to
Fredholm problems on manifolds with singularities and a formula for K-groups of
algebras of pseudodifferential operators.Comment: revised version; 25 pages; section with applications expande
Analytic and Reidemeister torsion for representations in finite type Hilbert modules
For a closed Riemannian manifold we extend the definition of analytic and
Reidemeister torsion associated to an orthogonal representation of fundamental
group on a Hilbert module of finite type over a finite von Neumann algebra. If
the representation is of determinant class we prove, generalizing the
Cheeger-M\"uller theorem, that the analytic and Reidemeister torsion are equal.
In particular, this proves the conjecture that for closed Riemannian manifolds
with positive Novikov-Shubin invariants, the L2 analytic and Reidemeister
torsions are equal.Comment: 78 pages, AMSTe
SENSITIVITY TO ANTIBIOTIC AND DISINFECTANTS AND PLASMID SPECTRUM OF ESCHERICHIA COLI STRAINS, CIRCULATING AMONGST THE SHIP COMPANY MEMBERS DURING THE LONG-TERM EXPEDITION
The article presents the results of unique researches of comparative study of microbiologic characteristics of E. rnli strains, isolated from the ship company members at different stages of the long-term expedition. It was established that cul-de-sac conditions promote formation of the population of microorganisms with more homogeneous spectrum of phenotypic and genotypic characters. It is showed that the reaction of shipboard E. coli population on the applying of antibiotics and taking disinfectant measures on the ship isn't just accommodation but more complicated process
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