217 research outputs found
Influence of the assimilation apparatus and productivity of white lupine plants
ArticleArtificial regulation of the growth and development of cultivated plants aimed to
increase biological productivity and improve the quality of eco-frienfly products is an important
goal of modern agricultural production. Application of the natural growth stimulators and
bacterial agents is quite relevant and effective. The field research was conducted on the basis of
the research farm ‘Agronomichne’ of Vinnytsia National Agrarian University, village
Agronomichne, Vinnytsa district, Vinnytsia region, Ukraine. Features of the growth and
development of white lupine (Lupinus albus L.) plants are examined. There has been established
a positive effect of the combination of inoculation with the bacterial agent and growth stimulator
on the productivity of white lupine, which is important for the formation of high and stable yields.
The papers presents the results of studies on the effect of pre-sowing seed treatment and foliar
nutrion under conditions of the right-bank Forest-Steppe of Ukraine on the assimilation apparatus
of white lupine plants. It has been established that bacterial agents and growth stimulators
increase white lupine productivity due to optimization of the studied technological methods of
cultivation. The optimal leaf surface area that provided maximum grain yield has been
determined. The research has established a positive effect of pre-sowing seed treatment with the
bacterial agent Rhizohumin and the growth stimulator Emistym C and foliar nutrition with
Emistym C on the chlorophyll content in the white lupine leaves. The influence of the investigated
technological methods on the formation of the assimilation surface area and chlorophyll synthesis
in the leaves of white lupine has been proved. The preparations studied induce intensive
development of the photosynthetic apparatus, yield increase, improvement of the yield structure
and they improve grain quality under conditions of right-bank Forest-Steppe of Ukraine. The
issue of seed bacterization and application of growth stimulators requires a more detailed study.
Theefore, such researches are relevant and significance in terms of both practical and scientific
value
Agroecological prospects of using corn hybrids for biogas production
Ukraine is an agricultural country with great agricultural potential for biogas
production, which is the key to fertile soils and favorable climatic conditions for energy crops,
including corn. The article analyzes the experience of using biogas in Ukraine and the world, its
mechanism of production. The leader in biogas production in the world is the European Union in
general and Germany in particular. The total number of biogas plants in Europe exceeds 11
thousand, of which 7.2 thousand in Germany. Іnstalled biogas, which is released in the process
of complex fermentation of organic waste, consists of a mixture of gases: methane – 55–75%,
carbon dioxide – 23–33%, hydrogen sulfide – 7%. An important sector of renewable energy
sources in biogas production is presented and the prospects for its use are determined. The energy
dependence of our country on the volumes of imported natural gas is analyzed. The main aspects
of biogas production are explored using renewable energy sources that are inexhaustible in our
crane and the phased operation of the biogas plant is investigated. The real advantages of the need
for biogas production and use in our country are outlined. Problems aimed at the development of
alternative energy have been proved in order to detect environmental pollution. It has been
established that in Ukraine the use of corn silage to improve the efficiency of biogas production
at existing biogas stations has not been used so far. The problems of increasing the yield of corn
plants have been proved not only by breeding and genetic methods, but also by cultivation
technology
Spinning strings, cosmic dislocations and chronology protection
A massless scalar field is quantized in the background of a spinning string
with cosmic dislocation. By increasing the spin density toward the dislocation
parameter, a region containing closed timelike curves (CTCs) eventually forms
around the defect. Correspondingly, the propagator tends to the ordinary cosmic
string propagator, leading therefore to a mean-square field fluctuation, which
remains well behaved throughout the process, unlike the vacuum expectation
value of the energy-momentum tensor, which diverges due to a subtle mechanism.
These results suggest that back reaction leads to the formation of a "horizon"
that protects from the appearance of CTCs.Comment: Published version, 4 pages, REVTeX
Isomer ratios and mean angular momenta of photonuclear reaction products
Isomer ratios and mean angular momenta are obtained both for photofission products of
237Np, 238U and for nuclei
122,120m,gSb and 117m,gIn. Photonuclear reactions
121Sb(γ,n)120m,gSb, 123Sb(γ,n)122m,gSb, 118Sn(γ,p)117m,gIn were studied in
the last cases. The technique of gamma-ray spectrometry for isomeric ratio determination was used. Target nuclei
were irradiated by bremsstrahlung spectrum of microtron M-30. Comparison of isomer ratios calculated by Empire II
code with experimental data was performed. Effects of the nuclear structure model parameters on values of isomer
ratios are discussedДосліджено ізомерні відношення та визначено середні кутові моменти для продуктів фотоділення ядер 238U і 237Np, а також виміряні ізомерні відношення для ядер 120,122m,gSb и 117m,gIn в реакціях (γ,n) та (γ,p). Опромінення проводилося гальмівними γ-квантами мікротрону М-30 з максимальною енергією спектру 16 та 15 МеВ. Досліджено залежності ізомерних відношень від кутових моментів збуджених ядер з використанням програми Empire II для розрахунку характеристик ядерних реакцій.Измерены изомерные отношения и извлечены средние угловые моменты для продуктов фотоделения ядер 238U и 237Np, а также измерены изомерные отношения для ядер 120,122m,gSb и 117m,gIn в реакциях (γ,n) и (γ,p). Облучение проводилось тормозными γ-квантами микротрона М-30 с максимальной энергией спектра 16 и 15 МэВ. Исследованы зависимости изомерных отношений от угловых моментов возбужденных ядер с использованием программы Empire II для расчета характеристик ядерных реакций
3D heterotic string theory: new approach and extremal solutions
We develop a new formalism for the bosonic sector of low-energy heterotic
string theory toroidally compactified to three dimensions. This formalism is
based on the use of some single non-quadratic real matrix potential which
transforms linearly under the action of subgroup of the three-dimensional
charging symmetries. We formulate a new charging symmetry invariant approach
for the symmetry generation and straightforward construction of asymptotically
flat solutions. Finally, using the developed approach and the established
formal analogy between the heterotic and Einstein-Maxwell theories, we
construct a general class of the heterotic string theory extremal solutions of
the Israel-Wilson-Perjes type. This class is asymptotically flat and charging
symmetry complete; it includes the extremal solutions constructed before and
possesses the non-trivial bosonic string theory limit.Comment: 20 pages in Late
QCD Strings as Constrained Grassmannian Sigma Model:
We present calculations for the effective action of string world sheet in R3
and R4 utilizing its correspondence with the constrained Grassmannian sigma
model. Minimal surfaces describe the dynamics of open strings while harmonic
surfaces describe that of closed strings. The one-loop effective action for
these are calculated with instanton and anti-instanton background, reprsenting
N-string interactions at the tree level. The effective action is found to be
the partition function of a classical modified Coulomb gas in the confining
phase, with a dynamically generated mass gap.Comment: 22 pages, Preprint: SFU HEP-116-9
Field Theoretical Quantum Effects on the Kerr Geometry
We study quantum aspects of the Einstein gravity with one time-like and one
space-like Killing vector commuting with each other. The theory is formulated
as a \coset nonlinear -model coupled to gravity. The quantum analysis
of the nonlinear -model part, which includes all the dynamical degrees
of freedom, can be carried out in a parallel way to ordinary nonlinear
-models in spite of the existence of an unusual coupling. This means
that we can investigate consistently the quantum properties of the Einstein
gravity, though we are limited to the fluctuations depending only on two
coordinates. We find the forms of the beta functions to all orders up to
numerical coefficients. Finally we consider the quantum effects of the
renormalization on the Kerr black hole as an example. It turns out that the
asymptotically flat region remains intact and stable, while, in a certain
approximation, it is shown that the inner geometry changes considerably however
small the quantum effects may be.Comment: 16 pages, LaTeX. The hep-th number added on the cover, and minor
typos correcte
Dressing with Control: using integrability to generate desired solutions to Einstein's equations
21 pages, no figures21 pages, no figures21 pages, no figures21 pages, no figuresMotivated by integrability of the sine-Gordon equation, we investigate a technique for constructing desired solutions to Einstein's equations by combining a dressing technique with a control-theory approach. After reviewing classical integrability, we recall two well-known Killing field reductions of Einstein's equations, unify them using a harmonic map formulation, and state two results on the integrability of the equations and solvability of the dressing system. The resulting algorithm is then combined with an asymptotic analysis to produce constraints on the degrees of freedom arising in the solution-generation mechanism. The approach is carried out explicitly for the Einstein vacuum equations. Applications of the technique to other geometric field theories are also discussed
Categorizing Different Approaches to the Cosmological Constant Problem
We have found that proposals addressing the old cosmological constant problem
come in various categories. The aim of this paper is to identify as many
different, credible mechanisms as possible and to provide them with a code for
future reference. We find that they all can be classified into five different
schemes of which we indicate the advantages and drawbacks.
Besides, we add a new approach based on a symmetry principle mapping real to
imaginary spacetime.Comment: updated version, accepted for publicatio
Effective interaction between helical bio-molecules
The effective interaction between two parallel strands of helical
bio-molecules, such as deoxyribose nucleic acids (DNA), is calculated using
computer simulations of the "primitive" model of electrolytes. In particular we
study a simple model for B-DNA incorporating explicitly its charge pattern as a
double-helix structure. The effective force and the effective torque exerted
onto the molecules depend on the central distance and on the relative
orientation. The contributions of nonlinear screening by monovalent counterions
to these forces and torques are analyzed and calculated for different salt
concentrations. As a result, we find that the sign of the force depends
sensitively on the relative orientation. For intermolecular distances smaller
than it can be both attractive and repulsive. Furthermore we report a
nonmonotonic behaviour of the effective force for increasing salt
concentration. Both features cannot be described within linear screening
theories. For large distances, on the other hand, the results agree with linear
screening theories provided the charge of the bio-molecules is suitably
renormalized.Comment: 18 pages, 18 figures included in text, 100 bibliog
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