633 research outputs found
Generation of microdissected DNA probes from metaphase chromosomes when chromosome identification by routine staining is impossible
Application of microdissected DNA libraries and DNA probes in numerous and various modern molecular cytogenetic studies showed them as an efficient and reliable tool in the analysis of chromosome reorganization during karyotypic evolution and in the diagnosis of human chromosome pathology. An important advantage of DNA probe generation by metaphase chromosome microdissection followed by sequence-independent polymerase chain reaction in comparison with the method of DNA probe generation using chromosome sorting is the possibility of DNA probe preparation from chromosomes of an individual sample without cell line establishment for the production of a large number of metaphase chromosomes. One of the main requirements for successful application of this technique is a possibility for identification of the chromosome of interest during its dissection and collection of its material from metaphase plates spread on the coverslip. In the present study, we developed and applied a technique for generation of microdissected DNA probes in the case when chromosome identification during microdissection appeared to be impossible. The technique was used for generation of two sets of Whole Chromosome Paints (WCPs) from all chromosomes of two species of free-living flatworms in the genus Macrostomum, M. mirumnovem and M. cliftonensis. The single-copy chromosome technique including separate collection of all chromosomes from one metaphase plate allowed us to generate WCPs that painted specifically the original chromosome by Chromosome In Situ Suppression Hybridization (CISS-Hybridization). CISS-Hybridization allowed identifying the original chromosome(s) used for DNA probe generation. Pooled WCPs derived from homologous chromosomes increased the intensity and specificity of chromosome painting provided by CISS-Hybridization. In the result, the obtained DNA probes appeared to be good enough for application in our studies devoted to analysis of karyotypic evolution in the genus Macrostomum and for analysis of chromosome rearrangements among the worms of laboratory cultures of M. mirumnovem
Locality of topological dynamics in Chern insulators
A system having macroscopic patches in different topological phases have no
well-defined global topological invariant. To treat such a case, the quantities
labeling different areas of the sample according to their topological state are
used, dubbed local topological markers. Here we study their dynamics. We
concentrate on two quantities, namely local Chern marker and on-site charge
induced by an applied magnetic field. We demonstrate that the time-dependent
local Chern marker is much more non-local object than equilibrium one.
Surprisingly, in large samples driven out of equilibrium, it leads to a simple
description of the local Chern marker's dynamics by a local continuity
equation. Also, we argue that the connection between the local Chern marker and
magnetic-field induced charge known in static holds out of equilibrium in some
experimentally relevant systems as well. This gives a clear physical
description of the marker's evolution and provides a simple recipe for
experimental estimation of the topological marker's value.Comment: 21 pages, 14 figures. The manuscript continues our earlier preprint
arXiv:2112.1357
Regions enriched for DNA repeats in chromosomes of Macrostomum mirumnovem, a species with a recent Whole Genome Duplication
The free-living flatworm Macrostomum mirumnovem is a neopolyploid species whose genome underwent a recent Whole Genome Duplication (WGD). In the result of chromosome fusions of the ancient haploid chromosome set, large metacentric chromosomes were formed. In addition to three pairs of small metacentrics, the current karyotype of M. mirumnovem contains two pairs of large metacentric chromosomes, MMI1 and MMI2. The generation of microdissected DNA libraries enriched for DNA repeats followed by DNA probe preparation and fluorescent in situ hybridization (FISH) were performed. The DNA probes obtained marked chromosome regions enriched for different DNA repeats in the M. mirumnovem chromosomes. The size and localization of these regions varied in different copies of large chromosomes. They varied even in homologous chromosomes, suggesting their divergence due to genome re-diploidization after a WGD. Besides the newly formed chromosome regions enriched for DNA repeats, B chromosomes were found in the karyotypes of the studied specimens of M. mirumnovem. These B chromosomes varied in size and morphology. FISH with microdissected DNA probes revealed that some Bs had a distinct DNA content. FISH could paint differently B chromosomes in different worms and even in the same sample. B chromosomes could carry a bright specific fluorescent signal or could show no fluorescent signal at all. In latter cases, the specific FISH signal could be absent even in the pericentromeric region of the B chromosome. Possible mechanisms of B chromosome formation and their further evolution are discussed. The results obtained indicate an important role that repetitive DNAs play in genome re-diploidization initiating a rapid differentiation of large chromosome copies. Taking together, karyotype peculiarities (a high level of intraspecific karyotypic diversity associated with chromosome number variation, structural chromosomal rearrangements, and the formation of new regions enriched for DNA repeats) and some phenotypic features of M. mirumnovem (small body size, short lifecycle, easy maintenance in the laboratory) make this species a perspective model in the studies of genomic and karyotypic evolution in species passed through a recent WGD event
On the Bethe Ansatz for the Jaynes-Cummings-Gaudin model
We investigate the quantum Jaynes-Cummings model - a particular case of the
Gaudin model with one of the spins being infinite. Starting from the Bethe
equations we derive Baxter's equation and from it a closed set of equations for
the eigenvalues of the commuting Hamiltonians. A scalar product in the
separated variables representation is found for which the commuting
Hamiltonians are Hermitian. In the semi classical limit the Bethe roots
accumulate on very specific curves in the complex plane. We give the equation
of these curves. They build up a system of cuts modeling the spectral curve as
a two sheeted cover of the complex plane. Finally, we extend some of these
results to the XXX Heisenberg spin chain.Comment: 16 page
Prospects for digitalization of sustainable development projects in the Russian Federation
Green bonds have become the most notable innovations in the field of sustainable financing over the past 10 years. The article discusses the problems of issuing and circulation of such financial market instruments, examines the opportunities that modern financial technologies provide for the development of this market segment. Technologies for investing in green bonds and sustainable development bonds remain burdensome and technologically complex, as they involve going through many stages and attracting a significant number of participants. In addition, to date, there has not been a liquid and transparent market for retail investors, and economic sanctions against Russia cut off the country from the financial markets of other countries for an indefinite time. However, the tools of sustainable development can now be successfully applied if innovative technologies such as blockchain technologies, smart contracts, the Internet of things and digital assets are used. The purpose of the study is to formulate recommendations for the progress of the sustainable development system in Russia, as well as to propose a mechanism for the tokenization of sustainable development bonds to attract and place funds from small investors in order to solve social and environmental problems of the Russian economy
Optical echo in photonic crystals
The dynamics of photonic wavepacket in the effective oscillator potential is
studied. The oscillator potential is constructed on a base of one dimensional
photonic crystal with a period of unit cell adiabatically varied in space. The
structure has a locally equidistant discrete spectrum. This leads to an echo
effect, i.e. the periodical reconstruction of the packet shape. The effect can
be observed in a nonlinear response of the system. Numerical estimations for
porous-silicon based structures are presented for femtosecond Ti:Sapphire laser
pump.Comment: 4 page
Continuous Time Quantum Monte Carlo Method for Fermions: Beyond Auxiliary Field Framework
Numerically exact continuous-time Quantum Monte Carlo algorithm for finite
fermionic systems with non-local interactions is proposed. The scheme is
particularly applicable for general multi-band time-dependent correlations
since it does not invoke Hubbard-Stratonovich transformation. The present
determinantal grand-canonical method is based on a stochastic series expansion
for the partition function in the interaction representation. The results for
the Green function and for the time-dependent susceptibility of multi-orbital
super-symmetric impurity model with a spin-flip interaction are presented
Narrowing the window for millicharged particles by CMB anisotropy
We calculate the cosmic microwave background (CMB) anisotropy spectrum in
models with millicharged particles of electric charge q\sim 10^{-6}-10^{-1} in
units of electron charge. We find that a large region of the parameter space
for the millicharged particles exists where their effect on the CMB spectrum is
similar to the effect of baryons. Using WMAP data on the CMB anisotropy and
assuming Big Bang nucleosynthesis value for the baryon abundance we find that
only a small fraction of cold dark matter, Omega_{mcp}h_0^2 < 0.007 (at 95%
CL), may consists of millicharged particles with the parameters (charge and
mass) from this region. This bound significantly narrows the allowed range of
the parameters of millicharged particles. In models without paraphoton
millicharged particles are now excluded as a dark matter candidate. We also
speculate that recent observation of 511 keV gamma-rays from the Galactic bulge
may be an indication that a (small) fraction of CDM is comprised of the
millicharged particles.Comment: 10 pages, 3 figures; v2: journal version, references adde
Nonlinear thermoelectric response of quantum dots: renormalized dual fermions out of equilibrium
The thermoelectric transport properties of nanostructured devices continue to
attract attention from theorists and experimentalist alike as the spatial
confinement allows for a controlled approach to transport properties of
correlated matter. Most of the existing work, however, focuses on
thermoelectric transport in the linear regime despite the fact that the
nonlinear conductance of correlated quantum dots has been studied in some
detail throughout the last decade. Here, we review our recent work on the
effect of particle-hole asymmetry on the nonlinear transport properties in the
vicinity of the strong coupling limit of Kondo-correlated quantum dots and
extend the underlying method, a renormalized superperturbation theory on the
Keldysh contour, to the thermal conductance in the nonlinear regime. We
determine the charge, energy, and heat current through the nanostructure and
study the nonlinear transport coefficients, the entropy production, and the
fate of the Wiedemann-Franz law in the non-thermal steady-state. Our approach
is based on a renormalized perturbation theory in terms of dual fermions around
the particle-hole symmetric strong-coupling limit.Comment: chapter contributed to 'New Materials for Thermoelectric
Applications: Theory and Experiment' Springer Series: NATO Science for Peace
and Security Series - B: Physics and Biophysics, Veljko Zlatic (Editor), Alex
Hewson (Editor). ISBN: 978-9400749863 (2012
Dispersionful analogues of Benney's equations and -wave systems
We recall Krichever's construction of additional flows to Benney's hierarchy,
attached to poles at finite distance of the Lax operator. Then we construct a
``dispersionful'' analogue of this hierarchy, in which the role of poles at
finite distance is played by Miura fields. We connect this hierarchy with
-wave systems, and prove several facts about the latter (Lax representation,
Chern-Simons-type Lagrangian, connection with Liouville equation,
-functions).Comment: 12 pages, latex, no figure
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