54 research outputs found
The temperature fields in electrically heated wires at crisis of boiling
The self-organization processes take place in several phenomena and physical objects and in particular they arise in metals in conditions of charge transfer. At liquid helium temperature in conditions of the increase of direct current flowing through bismuth, indium and tungsten there arise unstabilities of charge carries flux and this process exhibits itself in electromagnetic oscillations generation. This instability the authors refer to the mutual influence of the current flowing through the sample and magnetic field of the current. With this heat flux density through the sampleâs surfaces didnât exceed 0.1 W/sm2. Such a value of heat flux is Ńlose to the first boiling crisis but the author state that the nature of these phenomena is no case is connected with the heat removal specific features
Alternating-Spin Ladders in a Magnetic Field: New Magnetization Plateaux
We study numerically the formation of magnetization plateaux with the Lanczos
method in 2-leg ladders with mixed spins of magnitudes
located at alternating positions along the ladder and with dimerization
. For interchain coupling and , we find normalized
plateaux at starting at zero field and (saturation), while when
is columnar, another extra plateau at shows up. For
, when we find no plateau while for
we find four plateaux at . We also apply
several approximate analytical methods (Spin Wave Theory, Low-Energy Effective
Hamiltonians and Bosonization) to understand these findings and to conjeture
the behaviour of ferrimagnetic ladders with a bigger number of legs.Comment: REVTEX file, 7 pages, 6 eps Figure
Josephson effect in double-barrier superconductor-ferromagnet junctions
We study the Josephson effect in ballistic double-barrier SIFIS planar
junctions, consisting of bulk superconductors (S), a clean metallic ferromagnet
(F), and insulating interfaces (I). We solve the scattering problem based on
the Bogoliubov--de Gennes equations and derive a general expression for the dc
Josephson current, valid for arbitrary interfacial transparency and Fermi wave
vectors mismatch (FWVM). We consider the coherent regime in which quasiparticle
transmission resonances contribute significantly to the Andreev process. The
Josephson current is calculated for various parameters of the junction, and the
influence of both interfacial transparency and FWVM is analyzed. For thin
layers of strong ferromagnet and finite interfacial transparency, we find that
coherent (geometrical) oscillations of the maximum Josephson current are
superimposed on the oscillations related to the crossover between 0 and
states. For the same case we find that the temperature-induced
transition occurs if the junction is very close to the crossovers at zero
temperature.Comment: 13 pages, 6 figure
Genetic variation of RFXANK gene in Stavropol sheep breed
Using of NimbleGen sequencing technology for detection of polymorphisms RFXANK gene in Stavropolsheep breed, we found 20 SNPs. That is, two SNP in exons - c.63C>A (non synonymous) in exon II and c.498G>A in exon VI (synonymous). Others SNP is in introns: c.-343T>C, c.- 111T>G, c.187+328G>A, c.338-94G>A, c.632â124G>A, c.713-82G>A, c.187+62G>A, c.188-588G>C, c.188- 127C>T, c.565-44A>G, c.712+309C>T, c.712+354C>T, c.712+309C>T, c.187+394C>T, c.187+469A>G, c.187+71G>C, c.188-670A>G, c.713-107G>T. Some of them are presented together
Rational Diversification of a Promoter Providing Fine-Tuned Expression and Orthogonal Regulation for Synthetic Biology
Yeast is an ideal organism for the development and application of synthetic biology, yet there remain relatively few well-characterised biological parts suitable for precise engineering of this chassis. In order to address this current need, we present here a strategy that takes a single biological part, a promoter, and re-engineers it to produce a fine-graded output range promoter library and new regulated promoters desirable for orthogonal synthetic biology applications. A highly constitutive Saccharomyces cerevisiae promoter, PFY1p, was identified by bioinformatic approaches, characterised in vivo and diversified at its core sequence to create a 36-member promoter library. TetR regulation was introduced into PFY1p to create a synthetic inducible promoter (iPFY1p) that functions in an inverter device. Orthogonal and scalable regulation of synthetic promoters was then demonstrated for the first time using customisable Transcription Activator-Like Effectors (TALEs) modified and designed to act as orthogonal repressors for specific PFY1-based promoters. The ability to diversify a promoter at its core sequences and then independently target Transcription Activator-Like Orthogonal Repressors (TALORs) to virtually any of these sequences shows great promise toward the design and construction of future synthetic gene networks that encode complex âmulti-wireâ logic functions
The Flux-Line Lattice in Superconductors
Magnetic flux can penetrate a type-II superconductor in form of Abrikosov
vortices. These tend to arrange in a triangular flux-line lattice (FLL) which
is more or less perturbed by material inhomogeneities that pin the flux lines,
and in high- supercon- ductors (HTSC's) also by thermal fluctuations. Many
properties of the FLL are well described by the phenomenological
Ginzburg-Landau theory or by the electromagnetic London theory, which treats
the vortex core as a singularity. In Nb alloys and HTSC's the FLL is very soft
mainly because of the large magnetic penetration depth: The shear modulus of
the FLL is thus small and the tilt modulus is dispersive and becomes very small
for short distortion wavelength. This softness of the FLL is enhanced further
by the pronounced anisotropy and layered structure of HTSC's, which strongly
increases the penetration depth for currents along the c-axis of these uniaxial
crystals and may even cause a decoupling of two-dimensional vortex lattices in
the Cu-O layers. Thermal fluctuations and softening may melt the FLL and cause
thermally activated depinning of the flux lines or of the 2D pancake vortices
in the layers. Various phase transitions are predicted for the FLL in layered
HTSC's. The linear and nonlinear magnetic response of HTSC's gives rise to
interesting effects which strongly depend on the geometry of the experiment.Comment: Review paper for Rep.Prog.Phys., 124 narrow pages. The 30 figures do
not exist as postscript file
Catalytic synthesis of carbon nanostructures from polymer precursors
Exterior, general vie
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