7,381 research outputs found
One-dimensional structures behind twisted and untwisted superYang-Mills theory
We give a one-dimensional interpretation of the four-dimensional twisted N=1
superYang-Mills theory on a Kaehler manifold by performing an appropriate
dimensional reduction. We prove the existence of a 6-generator superalgebra,
which does not possess any invariant Lagrangian but contains two different
subalgebras that determine the twisted and untwisted formulations of the N=1
superYang-Mills theory.Comment: 12 pages. Final version to appear in Lett. Math. Phys. with improved
notation and misprints correcte
Long-distance entanglement and quantum teleportation in XX spin chains
Isotropic XX models of one-dimensional spin-1/2 chains are investigated with
the aim to elucidate the formal structure and the physical properties that
allow these systems to act as channels for long-distance, high-fidelity quantum
teleportation. We introduce two types of models: I) open, dimerized XX chains,
and II) open XX chains with small end bonds. For both models we obtain the
exact expressions for the end-to-end correlations and the scaling of the energy
gap with the length of the chain. We determine the end-to-end concurrence and
show that model I) supports true long-distance entanglement at zero
temperature, while model II) supports {\it ``quasi long-distance''}
entanglement that slowly falls off with the size of the chain. Due to the
different scalings of the gaps, respectively exponential for model I) and
algebraic in model II), we demonstrate that the latter allows for efficient
qubit teleportation with high fidelity in sufficiently long chains even at
moderately low temperatures.Comment: 9 pages, 6 figure
Excitation Energy Dependence of the Exciton Inner Ring
We report on the excitation energy dependence of the inner ring in the
exciton emission pattern. The contrast of the inner ring is found to decrease
with lowering excitation energy. Excitation by light tuned to the direct
exciton resonance is found to effectively suppress excitation-induced heating
of indirect excitons and facilitate the realization of a cold and dense exciton
gas. The excitation energy dependence of the inner ring is explained in terms
of exciton transport and cooling.Comment: 5 pages, 4 figure
Unstable Hadrons in Hot Hadron Gas in Laboratory and in the Early Universe
We study kinetic master equations for chemical reactions involving the
formation and the natural decay of unstable particles in a thermal bath. We
consider the decay channel of one into two particles, and the inverse process,
fusion of two thermal particles into one. We present the master equations the
evolution of the density of the unstable particles in the early Universe. We
obtain the thermal invariant reaction rate using as an input the free space
(vacuum) decay time and show the medium quantum effects on reaction relaxation time. As another laboratory example
we describe the process in thermal hadronic gas in
heavy-ion collisions. A particularly interesting application of our formalism
is the process in the early Universe.
We also explore the physics of and freeze-out in the
Universe.Comment: 13 pages, 9 figures, published in Physical Review
A method for obtaining plastid pigments from the biomass of Chlorella microalgae
Microalgae are distinguished from land plants by the high content of plastid pigments
and the biodiversity of carotenoids. The aim of this study is to develop a technology for extracting
a pigment complex from the biomass of the microalgae of the genus Chlorella and to determine
the extracted pigments’ composition. To obtain biomass, a crude cell suspension of microalgae
was used, which was obtained under laboratory conditions for pre-culture cultivation of
C. sorokiniana (strain 211-8k). The extraction of plastid pigments from air-dry biomass after
disintegration of cell membrane was performed in the 40 kHz mode. It was found that the highest
pigment content in ethanol extracts was observed after 30 min (870.0 ± 27.1 mg L
-1
) at 45−50 °C.
The pigments’ composition in the resulting total extracts was determined by spectrophotometry
and the Reverse Phase HPLC method. The established content of chlorophyll a in the obtained
extracts was 537.5 ± 10.0 mg L
-1
, the content of chlorophyll b was 182.5 ± 27.5 mg L
-1
; the
maximum output of the amount of carotenoids in extracts was 150.0 ± 10.0 mg L
-1
. Thus, the
main identified forms of carotenoids in extracts from the biomass of microalgae C. sorokiniana
were xanthophylls: lutein and fucoxanthin (18.6 and 4.7% of the amount of pigment in extract,
respectively) and β-carotene (1.8% of the amount of pigment). It is planned to further fractionate
the obtained total extracts of the pigment complex to obtain various forms of chlorophylls and
carotenoids to study the spectrum of physiological activity of plastid pigments
Oxidative dehydrogenation of 2,3,5-trimethyl-1,4-hydroquinone in the presence of titanium dioxide hydrogel
Liquid-phase oxidative dehydrogenation of 2,3,5-trimethyl-1,4-hydroquinone in the presence of titanium dioxide hydrogel was studied by a kinetic method. Associative interactions between the substrate, oxidant, and gel were detected by voltammetry and ESR and IR spectroscopy.Russian Foundation for Basic Researc
Efficient production of polar molecular Bose-Einstein condensates via an all-optical R-type atom-molecule adiabatic passage
We propose a scheme of "-type" photoassociative adiabatic passage (PAP) to
create polar molecular condensates from two different species of ultracold
atoms. Due to the presence of a quasi-coherent population trapping state in the
scheme, it is possible to associate atoms into molecules with a
\textit{low-power} photoassociation (PA) laser. One remarkable advantage of our
scheme is that a tunable atom-molecule coupling strength can be achieved by
using a time-dependent PA field, which exhibits larger flexibility than using a
tunable magnetic field. In addition, our results show that the PA intensity
required in the "-type" PAP could be greatly reduced compared to that in a
conventional "-type" one.Comment: 17 pages, 5 figures, to appear in New Journal of Physic
Impact of using the developed starter culture on the quality of sourdough, dough and wheat bread
ArticleThere is no technological necessity of sourdough usage when preparing wheat bread
as it can be prepared without sourdough but only with yeast using. However, sourdough helps to
solve such problems as fast microbial spoilage, unexpressed taste and smell, crumbling crumb.
The use of sourdough prepared with directional cultivation of microorganisms allows to produce
high-quality competitive bread. Developing a starter culture with an optimized microbial
composition was the purpose of this study, allowing the quality and the microbiological stability
of wheat bread improving. A new starter microbial composition for the sourdough was developed.
Lactic acid bacteria strains L. plantarum Е90, L. brevis Е120 and yeast S. cerevisiae Y139 were
selected for the new composition. It was proven that the rice products using to microorganism
immobilization allows saving the largest number of living cells after drying and during storage.
The rate of acid accumulation in sourdough was established. The sourdough dynamic viscosity
decrease at the end of fermentation by 2.2 times was established, which means that the
fermentation process leads to the sourdough liquefactio. The optimal dosage was established
(5–10% flour in sourdough). This dosage provided good physico-chemical and organoleptic
quality indicators of bread. It was proved that the sourdough usage allows getting good-quality
bread even when the flour with unsatisfactory amylolytic activity (high drop number) is used.
Slowing down the microbial spoilage in sourdough bread was proven. In general, the developed
sourdough wheat bread biotechnology improves bread quality and its resistance to the ropy-bread
disease
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