Optimization of electron beam parameters of LIA-10M accelerator

A numerical simulation of the LIA-10M accelerator was carried out. It is shown that at the existing configuration of the diode unit and maximal for LIA-10M injection parameters (3 MeV, 50 kA) significant (up to 40%) beam losses in the accelerating channel are possible. As a result of calculations the injector cathode geometry was optimized what permitted to avoid beam electron leakage onto the walls of accelerating channel and to improve significantly output parameters of the LIA-10M accelerator.Проведено численное моделирование ускорителя ЛИУ-10М. Показано, что при существующей конфигурации диодного узла и максимальных для ЛИУ-10М параметрах инжекции (3 МэВ, 50 кА) возможны значительные (до 40%) потери пучка в ускорительном тракте. В результате расчетов оптимизирована геометрия катода инжектора, что позволило избежать утечки электронов пучка на стенки ускорительного тракта и существенно улучшить выходные параметры ускорителя.Проведено чисельне моделювання прискорювача ЛІП-10М. Показано, що при існуючій конфігурації діодного вузла і максимальних для ЛІП-10М параметрах інжекції (3 МеВ, 50 кА) можливі значyі (до 40%) втрати пучка в прискорюючому тракті. У результаті розрахунків оптимізована геометрія катода інжектора, що дозволило уникнути витоку електронів пучка на стінки прискорюючого тракту і суттєво поліпшити вихідні параметри прискорювача

On high Q2Q^{2} behavior of the pion form factor for transitions γ∗γ→π0\gamma^{\ast} \gamma \to \pi^{0} and γ∗γ∗→π0\gamma ^{\ast} \gamma^{\ast} \to \pi^{0} within the nonlocal quark-pion model

The behavior of the transition pion form factor for processes \gamma^*\gamma -> \pi^0 and \gamma^* \gamma^* -> \pi^0 at large values of space-like photon momenta is estimated within the nonlocal covariant quark-pion model. It is shown that, in general, the coefficient of the leading asymptotic term depends dynamically on the ratio of the constituent quark mass and the average virtuality of quarks in the vacuum and kinematically on the ratio of photon virtualities. The kinematic dependence of the transition form factor allows us to obtain the relation between the pion light-cone distribution amplitude and the quark-pion vertex function. The dynamic dependence indicates that the transition form factor \gamma^* \gamma -> \pi^0 at high momentum transfers is very sensitive to the nonlocality size of nonperturbative fluctuations in the QCD vacuum.Comment: LaTex file with 3 ps-figure

Off-diagonal quark distribution functions of the pion within an effective single instanton approximation

We develop a relativistic quark model for pion structure, which incorporates the non-trivial structure of the vacuum of Quantum Chromodynamics as modelled by instantons. Pions are boundstates of quarks and the strong quark-pion vertex is determined from an instanton induced effective lagrangian. The interaction of the constituents of the pion with the external electromagnetic field is introduced in gauge invariant form. The parameters of the model, i.e., effective instanton radius and constituent quark masses, are obtained from the vacuum expectation values of the lowest dimensional quark and gluon operators and the low-energy observables of the pion. We apply the formalism to the calculation of the pion form factor by means of the isovector nonforward parton distributions and find agreement with the experimental data.Comment: LaTeX; altered version; references and figures added. Published: paper has been accepted for publication in Nucl. Phys.

Low-Energy Photodisintegration of the Deuteron and Big-Bang Nucleosynthesis

The photon analyzing power for the photodisintegration of the deuteron was measured for seven gamma-ray energies between 2.39 and 4.05 MeV using the linearly polarized gamma-ray beam of the High-Intensity Gamma-ray Source at the Duke Free-Electron Laser Laboratory. The data provide a stringent test of theoretical calculations for the inverse reaction, the neutron-proton radiative capture reaction at energies important for Big-Bang Nucleosynthesis. Our data are in excellent agreement with potential model and effective field theory calculations. Therefore, the uncertainty in the baryon density obtained from Big-Bang Nucleosynthesis can be reduced at least by 20%.Comment: 5 pages, 5 figure

Pion light-cone wave function and pion distribution amplitude in the Nambu-Jona-Lasinio model

We compute the pion light-cone wave function and the pion quark distribution amplitude in the Nambu-Jona-Lasinio model. We use the Pauli-Villars regularization method and as a result the distribution amplitude satisfies proper normalization and crossing properties. In the chiral limit we obtain the simple results, namely phi_pi(x)=1 for the pion distribution amplitude, and = -M / f_pi^2 for the second moment of the pion light-cone wave function, where M is the constituent quark mass and f_pi is the pion decay constant. After the QCD Gegenbauer evolution of the pion distribution amplitude good end-point behavior is recovered, and a satisfactory agreement with the analysis of the experimental data from CLEO is achieved. This allows us to determine the momentum scale corresponding to our model calculation, which is close to the value Q_0 = 313 MeV obtained earlier from the analogous analysis of the pion parton distribution function. The value of is, after the QCD evolution, around (400 MeV)^2. In addition, the model predicts a linear integral relation between the pion distribution amplitude and the parton distribution function of the pion, which holds at the leading-order QCD evolution.Comment: mistake in Eq.(38) correcte

Development of gradient diffusion strips to identify the potentiating effect of antimicrobial compounds against multidrug-resistant Klebsiella pneumoniae strains

Objective. The aim of the study was to develop gradient diffusion strips with substances capable of potentiating the action of antibiotics for the treatment of infections caused by multidrug-resistant strains of K. pneumoniae. Materials and Methods. The substances azidothymidine and baicalin were used to evaluate the joint action of combinations of antibiotics with substances that potentiate their action. Determination of susceptibility to combinations of antibiotics (gentamicin, cefotaxime, ciprofloxacin and chloramphenicol) with the listed substances was carried out by a modified gradient-diffusion method (cross-test). We used gradient diffusion strips, which was made in the Saint-Petersburg Pasteur Institute. We investigated clinical multidrug-resistant K. pneumoniae strains (n = 20). The result of the joint action of a combination of two compounds was assessed by calculating the fractional inhibitory concentrations ΣFIC. Results. The values of MIC decreased eightfold when azidothymidine was combined with gentamicin and two times when combined with ciprofloxacin. MIC values were not reduced by the combination of azidothymidine with cefotaxime or chloramphenicol. It has been established that azidothymidine has antibacterial activity against strains of K. pneumoniae: MIC50 – 1 μg/ml and MIC90 – 2 μg/ml. The MIC50 and MIC90 values for baicalin were > 256 μg/ml. A synergistic antibacterial effect was detected when azidothymidine was combined with gentamicin (ΣFIC 0.33–0.50). An additive effect (ΣFIC 0.65–0.84) was detected when azidothymidine was combined with ciprofloxacin. Baikalin reduced the MIC value of cefotaxime by half, and the MIC50 values for gentamicin also decreased by half. Baicalin did not affect the susceptibility of multidrug-resistant K. pneumoniae strains to ciprofloxacin and chloramphenicol. Synergism was detected in the combination of baicalin and cefotaxime (ΣFIC 0.52 – 0.75 – additive effect). Conclusions. The development of gradient diffusion strips with azidothymidine and baicalin makes it possible to simplify methods for assessing the joint action of combinations of these substances with antibiotics and to avoid time-consuming preparatory steps. Our study demonstrated that azidothymidine exhibits synergistic activity in combination with gentamicin and ciprofloxacin and baicalin – in combination with cefotaxime. Further studies are needed to evaluate the potential use of these combinations in practical healthcare

The Growth of CdTe Layer on GaAs Substrate by MBE

We present the results of growth of CdTe layer on (013)GaAs substrate. The sequence processes include the preparation of GaAs surface by chemical etching and annealing in ultra-high vacuum, the growth of ZnTe layer on atomically clean GaAs surface and then the growth of CdTe layer on ZnTe/GaAs. All processes were carried out without removing GaAs substrate from MBE set. The processes were controlled by RHEED and single wavelength ellipsometry. We found that the evaporation of arsenic oxides and gallium oxides from the (001)GaAs surface were observed at over 400 and 500°C, respectively. The growth of CdTe on (001)GaAs leads to appearance of mixture orientations because of large mismatch of lattice parameters. We study the growth of ZnTe on (001)GaAs and (013)GaAs substrates to prevent the growth of mixture orientations. We study the influence of cadmium and tellurium ratio in molecular fluxes and temperature on the growth mechanism of ZnTe and CdTe, crystal perfection, surface roughness and defects density. The optimal condition for growth of high quality thick CdTe on GaAs substrate were found

РЕЗУЛЬТАТИ РОЗРОБКИ МУЛЬТИМОДАЛЬНОЇ МОДЕЛІ ІЄРАРХІЧНИХ СТРУКТУРНО-ФУНКЦІОНАЛЬНИХ ПАТОГЕНЕТИЧНИХ ЛАНОК РОЗЛАДІВ ПСИХІЧНОЇ СФЕРИ ВНАСЛІДОК COVID-19

This text is the abstract of the report to the III Scientific and Practical Conference with International Participation "Psychiatry, Narcology, Clinical Psychology and General Medical Practice: Interdisciplinary Issues of the Present", March 22-23, 2024, Kyiv - online.Даний текст є тезами доповіді до ІІІ Науково-практичної конференції з міжнародною участю «Психіатрія, наркологія, клінічна психологія та загальна медична практика: міждисциплінарні питання сучасності», 22 – 23 березня 2024 р., м. Київ – online

Asymptotically exact dispersion relations for collective modes in a confined charged Fermi liquid

Using general local conservations laws we derive dispersion relations for edge modes in a slab of electron liquid confined by a symmetric potential. The dispersion relations are exact up to $\lambda^{2} q^{2}$, where $q$ is a wave vector and $\lambda$ is an effective screening length. For a harmonic external potential the dispersion relations are expressed in terms of the {\em exact} static pressure and dynamic shear modulus of a homogeneous liquid with the density taken at the slab core. We also derive a simple expression for the frequency shift of the dipole (Kohn) modes in nearly parabolic quantum dots in a magnetic field.Comment: RevTeX4, 4 pages. Revised version with new results on quantum qots and wires. Published in Phys.Rev.

Gauge invariance, causality and gluonic poles

We explore the electromagnetic gauge invariance of the hadron tensor of the Drell-Yan process with one transversely polarized hadron. The special role is played by the contour gauge for gluon fields. The prescription for the gluonic pole in the twist 3 correlator is related to causality property and compared with the prescriptions for exclusive hard processes. As a result of we get the extra contributions, which naively do not have an imaginary phase. The single spin asymmetry for the Drell-Yan process is enhanced by the factor of two.Comment: 9 pages, 2 figures; References and acknowledgements added