Ion-acoustic shocks with reflected ions: modeling and PIC simulations

Non-relativistic collisionless shock waves are widespread in space and astrophysical plasmas and are known as efficient particle accelerators. However, our understanding of collisionless shocks, including their structure and the mechanisms whereby they accelerate particles remains incomplete. We present here the results of numerical modeling of an ion-acoustic collisionless shock based on one-dimensional (1D) kinetic approximation both for electrons and ions with a real mass ratio. Special emphasis is made on the shock-reflected ions as the main driver of shock dissipation. The reflection efficiency, velocity distribution of reflected particles and the shock electrostatic structure are studied in terms of the shock parameters. Applications to particle acceleration in geophysical and astrophysical shocks are discussed.Comment: 6 pages, 7 figures, International Workshop "Complex Plasma Phenomena in the Laboratory and in the Universe", January 19-20, 2015, Rome, Ital

Clinical and Morphological Manifestations of Gastritis and Serum Cytokine Levels in Schoolchildren with Familial History of Gastric Cancer

Aim. A study of the clinical and morphological traits and cytokine profile of gastritis in schoolchildren with familial history of gastric cancer.Materials and methods. A cross-sectional questionnaire survey was conducted in Siberian regions (Tuva, Even-kiya, Aginskiy Buryat National District, Krasnoyarsk). A total of 3,343 schoolchildren aged 7–17 were surveyed for gastrointestinal complaints and history of gastric cancer in their 1st–2nd degree kindred. Oesophagogastroduo-denoscopy (OGDS) with gastric mucosa biopsy were performed in 463 respondents with complaints. Gastritis was graded in the Sydney classification. Serum cytokine levels (IL-2, IL-4, IL-8, IL-18, IL-1β, IFN-α, TNM-α) were obtained in enzyme immunoassays (ELISA).Results. Schoolchildren with gastritis and familial history of gastric cancer revealed a higher 59.8% rate of dyspeptic complaints vs. 40.8% in negative history (p = 0.001), as well as complaints of weekly heartburn in 14.2 and 8.3% cas-es (p = 0.019), respectively. In positive history and negative H. pylori tests, the cell immune response regulator IL-18 37 was revealed elevated in histology. In histologically verified H. pylori, no cross-cohort differences were observed in serum IL-18 by positive familial history of gastric cancer.Conclusion. Gastritis in schoolchildren with familial predisposition to gastric cancer more often associates with GERD and dyspepsia usually presented in postprandial distress syndrome. The cytokine regulation properties of gastritis in schoolchildren with familial history of gastric cancer have been reported

PARALLEL THREE-DIMENSTIONAL PIC CODE FOR BEAM-BEAM SIMULATION IN LINEAR COLLIDERS *

Abstract We present our parallel 3D3V particle-in-cell code for the numerical simulations of ultrarelativistic charged beams in supercolliders. In the algorithm we employ the three-dimensional set of Maxwell equations and the Vlasov-Liouville equation for the distribution function of beam particles in 6-dimensional phase space. The code allows performing numerical experiments with an arbitrary density distribution, beam crossing angle and relative offset. We present the results of numerical simulations of colliding beams using dummy parameters and parameters close to the ones of the newest ILC project

Features of the blood cytokine profile in gastroesophageal reflux disease in schoolchildren with gastritis and family history of peptic ulcer

Gastroesophageal reflux disease (GERD) is a common acid-dependent disease among the population, including children, with multifactorial genesis. It, like many other acid-dependent diseases (peptic ulcer, etc.) is associated with a family predisposition to the disease. Of interest is the study of the role of cytokines in the regulation of pathology in childhood, depending on the severity of a family history of peptic ulcer disease. Aim: to evaluate the levels of cytokines in the blood serum in case of family history of ulcerative diseases in schoolchildren with gastritis associated with GERD. In the course of a scientific study, 142 children with gastroenterological complaints aged 7-17 years were examined. The diagnosis of GERD was made in the presence of weekly heartburn in accordance with the global consensus on pathology in children. All subjects underwent gastroscopy with taking biopsy material from the gastric mucosa and morphological confirmation of their diagnosis of gastritis in accordance with the Sydney classification. The concentration of cytokines in blood serum (IL-2, IL-4, IL-6, IL-8, IL-10, IL-18, IL-1β, IFNα, TNFα) was obtained by enzyme immunoassay. During statistical processing, the χ2  and Mann–Whitney tests were used. The studies were approved by the ethics committee and informed consents of patients and their parents were obtained prior to the start of the study. The results of the study did not show significant differences in the concentration of cytokines in schoolchildren depending on the presence of GERD. In children with a family burden of peptic ulcer, GERD was detected more often (p = 0.054), which is probably a consequence of their increased acid formation. Changes in the cytokine profile of the blood were noted. During GERD, with aggravation of peptic ulcer, there was an increase in the replication of IL-4 (p = 0.027) and IFNα (p = 0.001). The increase in blood IFNα in children with GERD with family burden is obviously aimed at enhancing immune responses involving the whole body to damage. This is due to its functional role – participation in the immune response. Increased replication of IL-4, obviously, provides an increase in metabolic, immune processes in the body aimed at optimizing the course of proliferative processes in the esophageal mucosa under conditions of increased secretion of hydrochloric acid in the stomach. Thus, when a family history of peptic ulcer is aggravated in schoolchildren with gastritis associated with GERD, a number of links in the cytokine network (IL-4, IFNα) move to the systemic level of regulation

Prevalence of gastroesophageal reflux disease, gastroduodenal erosions and ulcers and their association with the family predisposition to peptic ulcer disease in Siberian schoolchildren

The aim is to study the prevalence of gastroesophageal reflux disease (GERD), gastroduodenal erosions and ulcers and their association with a family predisposition for ulcer disease in Siberian schoolchildren. Material and methods. We have examined schoolchildren aged 7–17 years in three regions of Siberia (Republic of Tyva, Evenkia and Buryatia) in localities identical to their socio-economic level. Data collected using a cross-sectional method using standardized questionnaires on the presence of gastroenterological complaints and information about ulcer disease of relatives in the 1st and 2nd generations in 1535 schoolchildren in Tuva, 790 in Buryatia and 1369 in Evenkia. Diagnosis of GERD was based on the presence of complaints of heartburn, in accordance with international consensus in the pediatric population. We performed gastroscopy randomly method in each region at schoolchildren with gastrointestinal complaints (283 children in Tyva, 110 in Buryatia, 205 in Evenkia). Results. There was an increase in the GERD frequency among Siberian children with anamnesis data on the presence of peptic ulcer in relatives (9.9 and 5.9 %, respectively, p = 0.0025). The most unfavorable situation has been observed in the population of schoolchildren of the Republic of Tuva (10.6 % with a burdened history and 9.3 % without it, p = 0.5389). We have not revealed the significant increase of gastroduodenal erosions and ulcers in children with a poor family history of peptic ulcer disease (12.6 and 10.4 %, respectively, p = 0.5263), including Tuva schoolchildren where they were more often detected. The GERD association with erosive ulcerative process in the mucous membrane of the stomach and duodenum was ambiguous and had population (regional) features in schoolchildren with a burdened family history of peptic ulcer disease. Conclusion. Siberian schoolchildren with a family predisposition to peptic ulcer disease have certain regional features in the association of gastroduodenal erosions and ulcers with GERD

Влияние Магнитного Поля На Реологические Свойства Растворов Эфиров Целлюлозы

The rheological properties, structure and phase transitions of hydroxypropyl cellulose in ethanol, dimethyl sulfoxide, ethylene glycol solutions and ethylcellulose in dimethylformamide so-lutions are studied using viscometry, the cloud-point method, polarization microscopy, the optical interferometry and a polarization photoelectric apparatus in the temperature range 280-360 K. The temperature-concentration regions of isotropic and anisotropic phases are determined for all sys-tems. The type of boundary curves of phase diagrams is compared with the chemical structure of macromolecules. It is shown that the constant magnetic field (3.6 kOe) leads to the orientation of macromolecules in solutions. The domain structure arising in solutions is fixed after evaporation of a solvent and shown in orientation of strips of the film relief. It was found that the flow curves of all solutions at 298 K in the range of shear rates from 0 to 15 s-1 are typically for the non-Newtonian liquids. It was found that the magnetic field leads to an increase in the viscosity of isotropic solutions and a decrease in the viscosity of anisotropic solutions. Both effects depend on the direction of the magnetic field lines. When the rotor-rotation axis is parallel to the direction of power lines of the magnetic field the change in the viscosity of solutions is greater than that at perpendicular orientation of the rotor-rotation axis and power lines of the magnetic field. The re-sults are discussed using representations about the changes in the macromolecule conformation and in the size and shape of the supramolecular particles in the solutions during flow under a magnetic field with different orientation of the power lines © 2021, ChemChemTech. All Rights Reserved

Surface Oscillations in Overdense Plasmas Irradiated by Ultrashort Laser Pulses

The generation of electron surface oscillations in overdense plasmas irradiated at normal incidence by an intense laser pulse is investigated. Two-dimensional (2D) particle-in-cell simulations show a transition from a planar, electrostatic oscillation at $2\omega$, with $\omega$ the laser frequency, to a 2D electromagnetic oscillation at frequency $\omega$ and wavevector $k>\omega/c$. A new electron parametric instability, involving the decay of a 1D electrostatic oscillation into two surface waves, is introduced to explain the basic features of the 2D oscillations. This effect leads to the rippling of the plasma surface within a few laser cycles, and is likely to have a strong impact on laser interaction with solid targets.Comment: 9 pages (LaTeX, Revtex4), 4 GIF color figures, accepted for publication in Phys. Rev. Let

Charged particle acceleration in nonuniform plasmas

The high-gradient electron acceleration schemes that have been demonstrated using LWFA appear promising for the development of plasma-based laser accelerators into practical devices. However, a question still exists: how to avoid the wake field deterioration and the loss of the phase synchronism between the plasma wave and the electrons that prevent them from being accelerated up to the theoretical limit. In order to obtain the highest possible values of the wake electric field one must use as intense laser pulses as possible i.e., pulses with dimensionless amplitudes a {much_gt} 1. Pulses that have a dimensionless amplitude larger than one tend to be subject to a host of instabilities, such as relativistic self-focusing, self modulation and stimulated Raman scattering, that affect their propagation in the plasma. Such processes could be beneficial, in so far as they increase the pulse energy density, enhance the wake field generation, and provide the mechanism for transporting the laser radiation over several Rayleigh lengths without diffraction spreading. However, it is still far from certain that these processes can be exploited in a controlled form and can lead to regular, stationary wake fields. It is known that, in order to create good quality wake fields, it would be preferable to use laser pulses with steep fronts of order {lambda}{sub p}. The present paper aims at analyzing the influence of the laser pulse shape and of the plasma nonuniformity on the charged particle acceleration. This study is based on the results obtained with one dimensional PIC simulations

ЗАБОЛЕВАНИЯ ГАСТРОДУОДЕНАЛЬНОЙ ЗОНЫ, АССОЦИИРОВАННЫЕ С HELICOBACTER РYLORI, У ДЕТЕЙ — КОРЕННЫХ ЖИТЕЛЕЙ ТЫВЫ И ЭВЕНКИИ

We carried out clinical morphological examination for 80 Evenks (Evenkia is in the North of Siberia) and 90 Tyvins (Tyva Republic is in the South of Siberia) in the ages of 7 to 17 years aimed at studying H. pylori infection and its associations with gastroduodenal diseases in children. We found increased level of contamination and its connection with dyspepsia syndrome in the Evenks. Both ethnic populations show the association of the infection with gastric activity. At the same time we didn’t mark the higher rate of contamination in children with erosive ulcer lesion of gastroduodenal mucosa. We found the increased level of mucosa bacterial dissemination with H. pylori in the Evenks who had destructive changes.Проведено клинико-морфологическое обследование 80 эвенков (Эвенкия — Север Сибири) и 90 тувинцев (Республики Тыва — Юг Сибири) в возрасте 7—17 лет с целью изучения инфицирования H. pylori и ассоциации инфекции с заболеваниями гастродуоденальной зоны у детей. Установлено увеличение инфицирования и его связь с синдромом диспепсии у эвенков. В обеих этнических популяциях прослеживалась ассоциация инфекции с активностью гастрита. Тогда как увеличения инфицирования детей с эрозивно-язвенными поражениями слизистой гастродуоденальной зоны не отмечено. Однако у эвенков с деструктивными изменениями имелось увеличение степени бактериальной обсемененности H. pylori слизистой