Experimental and Theoretical Investigation into the Effect of the Electron Velocity Distribution on Chaotic Oscillations in an Electron Beam under Virtual Cathode Formation Conditions

The effect of the electron transverse and longitudinal velocity spread at the entrance to the interaction space on wide-band chaotic oscillations in intense multiple-velocity beams is studied theoretically and numerically under the conditions of formation of a virtual cathode. It is found that an increase in the electron velocity spread causes chaotization of virtual cathode oscillations. An insight into physical processes taking place in a virtual cathode multiple velocity beam is gained by numerical simulation. The chaotization of the oscillations is shown to be associated with additional electron structures, which were separated out by constructing charged particle distribution functions.Comment: 9 pages, 8 figure

Investigation of the Chaotic Dynamics of an Electron Beam with a Virtual Cathode in an External Magnetic Field

The effect of the strength of the focusing magnetic field on chaotic dynamic processes occurring inan electron beam with a virtual cathode, as well as on the processes whereby the structures form in the beamand interact with each other, is studied by means of two-dimensional numerical simulations based on solving a self-consistent set of Vlasov-Maxwell equations. It is shown that, as the focusing magnetic field is decreased,the dynamics of an electron beam with a virtual cathode becomes more complicated due to the formation andinteraction of spatio-temporal longitudinal and transverse structures in the interaction region of a vircator. The optimum efficiency of the interaction of an electron beam with the electromagnetic field of the vircator isachieved at a comparatively weak external magnetic field and is determined by the fundamentally two-dimensional nature of the motion of the beam electrons near the virtual cathode.Comment: 12 pages, 8 figure

q-Functional Wick's theorems for particles with exotic statistics

In the paper we begin a description of functional methods of quantum field theory for systems of interacting q-particles. These particles obey exotic statistics and are the q-generalization of the colored particles which appear in many problems of condensed matter physics, magnetism and quantum optics. Motivated by the general ideas of standard field theory we prove the q-functional analogues of Hori's formulation of Wick's theorems for the different ordered q-particle creation and annihilation operators. The formulae have the same formal expressions as fermionic and bosonic ones but differ by a nature of fields. This allows us to derive the perturbation series for the theory and develop analogues of standard quantum field theory constructions in q-functional form.Comment: 15 pages, LaTeX, submitted to J.Phys.

Использование сорбента на основе сверхсшитого стирол-дивинилбензольного сополимера с иммобилизованным ЛПС-селективным лигандом при гемоперфузии для лечения пациентов с септическим шоком

Aim of the study: to evaluate safety and feasibility of clinical use of an extracorporeal blood adsorber based on a hypercrosslinked styrene-divinylbenzene copolymer with immobilized lipopolysaccharide (LPS)-selective ligand designed to remove endotoxins from the bloodstream to treat patients with septic shock.Materials and methods. Nine patients (mean age 58 years, 5 men and 4 women, initial median APACHE II score 28 points, SOFA score 10 points) with confirmed Gram-negative bacterial infection and septic shock (SEPSIS-3, 2016) underwent LPS-selective hemoperfusion using an extracorporeal blood adsorber based on a hypercrosslinked styrene divinylbenzene copolymer with immobilized LPS-selective ligand for 6 hours, followed by prolonged veno-venous hemodiafiltration. Before the hemoperfusion (day 0), immediately after it, a day after its end (day 1) and once daily for the next 4 days we assessed the hemodynamic parameters, oxygenation, organ failure signs, white blood cell count, procalcitonin, C-reactive protein, clinical chemistry parameters.Results. Hemoperfusion resulted in a rapid decrease in the endotoxin activity (EAA test), more than twofold decrease in plasma level of interleukin-1 (immunoenzyme test). At the end of the procedure, the plasma lactate level decreased to normal values by day 3, pH values restored to normal within 1-2 days. The noradrenaline requirement rapidly decreased and completely resolved within 1-3 days, which corresponded to the restoration of mean blood pressure values. The values of the PaO2/FiO2 oxygenation index increased significantly after 24 hours, and the median values of 300 were maintained during all subsequent days of observation. During the first day, hemoperfudion caused a rapid decline in APACHE II and SOFA scores, while acute renal failure (estimated by urea and creatinine levels) resolved gradually by day 5. The hemoperfusion did not affect the unchanged coagulation parameters (prothrombin, fibrinogen, INR). During the first day after the procedure, we observed a short-term 1.5-fold decrease in platelet count with subsequent recovery by days 2-3 in most patients. Two patients, both differing from the rest of the patients prior to treatment in the highest values of APACHE II score (above 30), APTT (above 40) and endotoxin activity in EAA test (above 0.9), died on the 4th and 8th days of treatment. The rest of the patients survived, with clinical improvement in all parameters.Conclusion. The results of extracorporeal blood purification using Efferon LPS extracorporeal blood adsorber indicate a high therapeutic potential of the method and suggest the need for extended clinical trials to assess its clinical efficacy in ICU to reduce the high mortality in patients with septic shock.Цель исследования: оценка безопасности и определение возможности применения гемосорбента на основе сверхсшитого стирол-дивинилбензольного сополимера с иммобилизованным липополисахарид (ЛПС)-селективным лигандом, предназначенного для удаления из кровотока эндотоксинов, для лечения пациентов с септическим шоком.Материалы и методы. Девяти пациентам (средний возраст 58 лет, 5 мужчин и 4 женщины, начальные значения медиан для APACHE II 28 баллов, для SOFA 10 баллов) с подтвержденной грам-не-гативной бактериальной инфекцией и септическим шоком (СЕПСИС-3, 2016) проводили ЛПС-селек-тивную гемоперфузию (ЛСГ) с помощью колонки с сорбентом на основе сверхсшитого стирол-дивинилбензольного сополимера с иммобилизованным ЛПС-селективным лигандом в течении 6 часов с последующей продленной вено-венозной гемодиафильтрацией. До ЛСГ (день 0), сразу после нее, через сутки после ее окончания (день 1) и ежедневно на протяжении последующих 4-x суток определяли показатели гемодинамики, оксигенации, органной недостаточности, содержание лейкоцитов, прокальцитонина, С-реактивного белка, биохимические показатели.Результаты. Проведение ЛСГ приводило к быстрому снижению активности эндотоксина (ЕАА тест), более чем двукратному уменьшению содержания интерлейкина-1 (иммуноферментный тест) в плазме крови. По окончании процедуры снижалась концентрация лактата в плазме крови, доходя до нормальных значений на 3-е сутки, восстанавливались до нормальных значения рН на 1-2-е сутки. Потребность в норадреналине быстро снижалась и полностью прекращалась на 1-3-е сутки, что соответствовало восстановлению значений среднего артериального давления. Значения индекса оксигенации PaO2/FiO2 значимо повышались через сутки, значения медианы 300 удерживались на протяжении всех последующих дней наблюдения. Проведение ЛСГ обеспечивало быстрое, в течение первых суток, снижение показателей по шкалам APACHEII и SOFA, в то время как показатели острой почечной недостаточности (содержание мочевины и креатинина) градуально снижались вплоть до нормальных значений к 5- му дню. Проведение ЛСГ не приводило к изменению ненарушенных показателей системы свертывания (протромбина, фибриногена, МНО). В течение первых суток после процедуры наблюдали кратковременное 1,5-кратное снижение содержания тромбоцитов с последующим восстановлением на 2-3-и сутки у большинства пациентов. Двое пациентов, отличающихся до лечения от остальных пациентов наиболее высокими значениями оценки по шкале APACHEII (выше 30), по показателям АЧТВ (свыше 40) и значениям акивности эндотоксина в тесте ЕАА (свыше 0,9), погибли на 4-й и 8-й дни лечения. Остальные пациенты живы, с клиническим улучшением по всем показателям.Заключение. Результаты проведения экстракорпорального очищения крови с помощью колонки с сорбентом на основе сверхсшитого стирол-дивинилбензольного сополимера с иммобилизованным ЛПС-селективным лигандом указывают на высокий терапевтический потенциал примененного метода и обосновывают необходимость проведения расширенных клинических исследований с целью оценки эффективности его использования в клинической практике ОРИТ для снижения высокой летальности пациентов с септическим шоком

Direct Observation of an Interface Dipole between Two Metallic Oxides Caused by Localized Oxygen Vacancies

Oxygen vacancies are increasingly recognized to play a role in phenomena observed at transition-metal oxide interfaces. Here we report a study of SrRuO3/La0.7Sr0.3MnO3 (SRO/LSMO) interfaces using a combination of quantitative aberration-corrected scanning transmission electron microscopy, electron energy loss spectroscopy, and density-functional calculations. Cation displacements are observed at the interface, indicative of a dipole-like electric field even though both materials are nominally metallic. The observed displacements are reproduced by theory if O vacancies are present in the near-interface LSMO layers. The results suggest that atomic-scale structural mapping can serve as a quantitative indicator of the presence of O vacancies at interfaces

Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR

Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (mu_B > 500 MeV), effects of chiral symmetry, and the equation-of-state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2022, in the context of the worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal

Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

Simultaneous measurement of the ratio B(t->Wb)/B(t->Wq) and the top quark pair production cross section with the D0 detector at sqrt(s)=1.96 TeV

We present the first simultaneous measurement of the ratio of branching fractions, R=B(t->Wb)/B(t->Wq), with q being a d, s, or b quark, and the top quark pair production cross section sigma_ttbar in the lepton plus jets channel using 0.9 fb-1 of ppbar collision data at sqrt(s)=1.96 TeV collected with the D0 detector. We extract R and sigma_ttbar by analyzing samples of events with 0, 1 and >= 2 identified b jets. We measure R = 0.97 +0.09-0.08 (stat+syst) and sigma_ttbar = 8.18 +0.90-0.84 (stat+syst)} +/-0.50 (lumi) pb, in agreement with the standard model prediction.Comment: submitted to Phys.Rev.Letter