Efficiency of Electron-Positron Pair Productionby Neutrino Flux from Accretion Disk of a Kerr Black Hole

Dominant processes of neutrino production and neutrino-induced \ep-pair production are examined in the model of a disk hyper-accreting onto a Kerr black hole. The efficiency of plasma production by a neutrino flux from the disk, obtained for the both cases of presence and absence of a magnetic field, is found to be no more than several tenths of percent and, therefore, not enough for the origin of cosmological gamma-ray bursts.Comment: 8 pages, 1 figur

Semiclassical approach to the decay of protons in circular motion under the influence of gravitational fields

We investigate the possible decay of protons in geodesic circular motion around neutral compact objects. Weak and strong decay rates and the associated emitted powers are calculated using a semi-classical approach. Our results are discussed with respect to distinct ones in the literature, which consider the decay of accelerated protons in electromagnetic fields. A number of consistency checks are presented along the paper.Comment: To appear in Physical Review

FUNCTIONAL ACTIVITY OF NEUTROPHILS AND HEMOSTASIS PATTERN IN PATIENTS WITH ACUTE DESTRUCTIVE PANCREATITIS

The aim of present study was to investigate relationships between indicators of functional activity of neutrophilic granulocytes, and hemostasis parameters in patients with acute destructive pancreatitis (ADP). The study included thirty-three patients with ADP. 35 healthy persons were examined as a control group. The phagocytosis level in neutrophils was determined by flow cytometry using FITC-labeled staphylococcal protein A. We have calculated the percentage of fluorescent neutrophils as phagocytic index, and average cell fluorescence assumed phagocytic number. The intensity of respiratory burst observed in neutrophil samples was evaluated using chemiluminescence assay. All the persons under study were also tested for blood coagulation and vascular-platelet hemostasis. It was found that the ADP patients with decreased number of phagocytic neutrophils in the blood showed a decrease in respiratory burst intensity in the neutrophils. Moreover, spontaneous and induced synthesis of the primary reactive oxygen species (ROS) in neutrophils of ADP patients proceeded faster than in healthy people, but its intensity was much lower. The maximal level of spontaneous and induced synthesis of secondary ROS in neutrophils of patients was significantly higher than in healthy individuals, but its rapid may be generally characterized by insufficient respiratory burst in these patients. A reduced neutrophil phagocytic activity and kinetic characteristics of primary and secondary ROS synthesis may be attributed to the effects produced by pancreatic enzymes entering blood flow which may alter functional activity of the blood neutrophils. Concerning hemostasis in patients with ADP, some disturbances were found only in the coagulation link which seem to depend on increase in fibrinogen, soluble fibrin monomer complexes and D-dimer in blood plasma, along with reduced antithrombin III levels. Such a change in blood coagulation indexes is typical to inflammatory processes and presumes activation of the coagulation cascade and higher risk of septic complications. In patients with ADP, we have found a significantly increased number of correlations between indicators of functional activity of neutrophils and hemostasis parameters. This analysis revealed a relationship by the patients with ADP reflect some unidirectional changes in functional activity of neutrophils (as phagocytosis and respiratory burst), and blood coagulation parameters (as blood clotting and vascular/ platelet links). The changes in functional activity of neutrophils and the state of hemostasis in the ADP patients, as well as correlations between their alterations are omvolved into the pathogenesis of this disorder, and determine potential mechanisms for evolving complications

Functional activity of peripheral blood monocytes in patients with opisthorchiasis coupled to liver fibrosis intensity

The aim is to examine activity of peripheral blood monocytes from patients with opisthorchiasis coupled to intensity of liver fibrosis. Materials and Methods. A total of 74 patients with chronic opisthorchiasis (39 males and 35 females, average age 42.3 years) and 32 apparently healthy subjects (17 males and 15 females, average age 41.5 years) aged 24 to 60 years were enrolled. Opisthorchiasis was mainly diagnosed by parasitological assays to detect adult parasite eggs or bodies in duodenal contents and/or feces in all 74 patients. Liver fibrosis was assessed by elastometry according to the METAVIR scale. Functional activity of peripheral blood monocytes was performed in all patients with opisthorchiasis and healthy individuals from the control group by chemiluminescent analysis to measure intensity of reactive oxygen species production in lucigenin- and luminol-dependent spontaneous and zymosan-induced reactions. Results. Liver fibrosis F2 and F3—F4 stage according to METAVIR scale was found in 20.3% and 17.6% of patients with opisthorchiasis, respectively. While analyzing total pool of reactive oxygen species in the luminol-dependent process in patients with opisthorchiasis, a significantly decreased monocyte functional activity was observed as compared to healthy subjects that was evidenced by significantly decreased maximum intensity of produced reactive oxygen species as well as area under the chemiluminescence curve both in spontaneous and zymosan-induced reaction. Such parameters in liver fibrosis F3—F4 compared to F0—F1 in zymosan-induced response were lowered. Monocyte functional activity in spontaneous luminol-dependent reaction did not differ significantly depending on liver fibrosis intensity in patients with opisthorchiasis. The phagocytosis activation index in patients with opisthorchiasis with liver fibrosis F3—F4 compared to F0—F1 and F2 stage was lower. Similar changes were observed in the lucigenin-dependent reaction. Conclusion. The data obtained undoubtedly provide promising evidence to interpret the mechanisms behind liver fibrosis in patients with opisthorchiasis and create new opportunities for development of diagnostic and therapeutic technologies

Lower Bound on the Magnetic Field Strength of a Magnetar from Analysis of SGR Giant Flares

Based on the magnetar model, we have studied in detail the processes of neutrino cooling of an electron--positron plasma generating an SGR giant flare and the influence of the magnetar magnetic field on these processes. Electron--positron pair annihilation and synchrotron neutrino emission are shown to make a dominant contribution to the neutrino emissivity of such a plasma. We have calculated the neutrino energy losses from a plasma-filled region at the long tail stage of the SGR 0526--66, SGR 1806--20, and SGR 1900+14 giant flares. This plasma can emit the energy observed in an SGR giant flare only in the presence of a strong magnetic field suppressing its neutrino energy losses. We have obtained a lower bound on the magnetic field strength and showed this value to be higher than the upper limit following from an estimate of the magnetic dipole losses for the magnetars being analyzed in a wide range of magnetar model parameters. Thus, it is problematic to explain the observed energy release at the long tail stage of an SGR giant flare in terms of the magnetar model.Comment: 18 pages, 5 figure

Применение математического метода локальных вариаций для решения задач пластического формоизменения металлических, порошковыхи нанокомпозиционных материалов

The paper considers an approach to solving plastic forming problems using a variational approach, which allows to determine the stress-strain state and the technological parameters associated with it, taking into account the combination of rheological properties of the materials being processed. On the basis of the first principle of energy in mechanics, which is built on the theorems on extremal properties, when the absolute minimum of the total power of the formchanging process corresponds to a real velocity field, energy functional has been composed. The energy functional is a power balance of internal and external forces. As the power of internal forces, we understand the cost of power of plastic deformation; power associated with the presence of velocities discontinuity surfaces in the volume of a deformable medium; power of friction forces, on the contact boundary with the tool; inertial component of power expended on the change in kinetic energy. Such a formulation makes it possible to investigate the processes of high-speed strain in the same way. This functional characterizes the state of the material under these processing conditions. To solve this functional, the method of local variations is applied, which refers to the direct numerical methods of the calculus of variations. An algorithm for calculating the power of plastic strains for the process of reverse extrusion of a glass from an isotropic, rigid-plastic material is given as an example.В работе рассмотрен подход к решению задач пластического формоизменения с использование вариационного подхода, который позволяет определить напряженнодеформированное состояние и связанные с ним технологические параметры с учетом совокупности реологических свойств обрабатываемых материалов. На основе первого энергетического принципа механики, строящегося на теоремах об экстремальных свойствах, когда действительному полю скоростей соответствует абсолютный минимум полной мощности процесса формоизменения, составлен энергетический функционал. Энергетический функционал представляет собой баланс мощности внутренних и внешних сил. Под мощностью внутренних сил понимаются затраты мощности пластической деформации; мощности, связанной с наличием поверхностей разрыва скоростей в объеме деформируемой среды; мощности сил трения, на контактной границе с инструментом; инерционная компонента мощности, затрачиваемая на изменение кинетической энергии. Такая постановка дает возможность исследовать так же и процессы высокоскоростного деформирования, Данный функционал характеризует состояние материала при данных условиях обработки. Для решения данного функционала применен метод локальных вариаций, который относится к прямым численным методам вариационного исчисления. Приведен, в качестве примера, алгоритм расчета мощности пластической деформации для процесса обратного выдавливания стакана из изотропного, жесткопластического материала

FORMATION OF CELLULAR STRUCTURES FOR MODELING AND EXPERIMENTAL EVALUATION OF PROPERTIES OF ADDITIVE MANUFACTURING PRODUCTS

The technique of modeling and experimental evaluation of effective physical and mechanical properties of additive manufacturing products obtained by layer-by-layer laser synthesis on the basis of powder alloys 07X18H12M2 (analog AISI 316L) and 08XN53BMTYU (analog Inconel 718), with the formation of cellular structures in them, is presented.Представлена методика моделирования и экспериментальной оценки эффективных физико.механических свойств изделий аддитивного производства, полученных методом послойного лазерного синтеза на базе порошковых сплавов 07Х18Н12М2 (аналог AISI 316L) и 08ХН53БМТЮ (аналог Inconel 718), с помощью формирования в них ячеистых структур.Исследование проведено в рамках государственного задания Министерства образования и науки Российской Федерации, проект № 11.6682.2017/8.9