Construction of the Initial Part of a Ion Linear Accelerator from Similar Short Cavities

The construction of the initial part of a normally conducting linac for hydrogen ion beams with a pulsed current of ~20 mA up to an energy of ~70 MeV is considered. The RFQ at a frequency of ~160 MHz accelerates ions to an energy of ~4 MeV. Further acceleration is carried out at a doubled frequency by short, up to $5\beta\lambda$, cavities, operating in the TM010 mode, with drift tubes. Focusing is carried out by doublets of quadrupole lenses placed between the cavities. The structure of the accelerating-focusing channel, with given beam parameters, with reserves provides both the conditions for stable longitudinal and transverse motion of particles, and reliable technical implementation. The main results of the simulations of particle dynamics and the main parameters of the elements of the channel are presented. The possibility of constructing an linac with a higher output energy is analyzed.Comment: in Russian languag

Exact Self-consistent Particle-like Solutions to the Equations of Nonlinear Scalar Electrodynamics in General Relativity

Exact self-consistent particle-like solutions with spherical and/or cylindrical symmetry to the equations governing the interacting system of scalar, electromagnetic and gravitational fields have been obtained. As a particular case it is shown that the equations of motion admit a special kind of solutions with sharp boundary known as droplets. For these solutions, the physical fields vanish and the space-time is flat outside of the critical sphere or cylinder. Therefore, the mass and the electric charge of these configurations are zero.Comment: 17 pages, Submitted to the International Journal of Theoretical Physic

О применении технологий параллельного программирования для задач матричной алгебры в приложении к спектральному методу анализа, синтеза и идентификации систем управления

The article describes the matrix algebra libraries based on the modern technologies of parallel programming for the Spectrum software, which can use a spectral method (in the spectral form of mathematical description) to analyse, synthesise and identify deterministic and stochastic dynamical systems. The developed matrix algebra libraries use the following technologies for the GPUs: OmniThreadLibrary, OpenMP, Intel Threading Building Blocks, Intel Cilk Plus for CPUs nVidia CUDA, OpenCL, and Microsoft Accelerated Massive Parallelism.The developed libraries support matrices with real elements (single and double precision). The matrix dimensions are limited by 32-bit or 64-bit memory model and computer configuration. These libraries are general-purpose and can be used not only for the Spectrum software. They can also find application in the other projects where there is a need to perform operations with large matrices.The article provides a comparative analysis of the libraries developed for various matrix operations (addition, subtraction, scalar multiplication, multiplication, powers of matrices, tensor multiplication, transpose, inverse matrix, finding a solution of the system of linear equations) through the numerical experiments using different CPU and GPU. The article contains sample programs and performance test results for matrix multiplication, which requires most of all computational resources in regard to the other operations.В статье описываются библиотеки матричной алгебры, разработанные с применением современных технологий параллельного программирования для расчетной системы Spectrum. Расчетная система Spectrum может применяться в разных задачах анализа, синтеза и идентификации детерминированных и стохастических динамических систем спектральным методом (в спектральной форме математического описания). Проведен сравнительный анализ разработанных библиотек на основе вычислительных экспериментов с применением различного аппаратного обеспечения (центральных процессоров и графических процессоров видеоадаптеров). DOI: 10.7463/mathm.0116.084107

Use of Levosimendan in Cardiac Anesthesiology

The authors consider the main aspects of the rational use of the novel inotropic drug levosimendan in cardiosurgical patients on the basis of the results of the trials described in the literature and on their own findings in this review. The purpose of the analysis made was to provide a rationale for the effective use of this drug. The review shows the role of the ultrasound indicator left ventricular ejection fraction, the prognostic scale EuroSCORE, and the natriuretic peptides NT-proBNP and BNP in defining indications for levosimendan administration for preoperative preparation. There are original data on the lower level of the natriuretic peptides due to levosimendan therapy. The target hemodynamic monitoring values indicating that it is essential to use levosimendan in postperfusion heart failure are discussed. It is shown that it is expedient to use levosimendan simultaneously with traditional medical measures, by taking into account the pharmacokinetic features of a calcium sensitizer. The problem of levosimendan readministration in patients operated on the heart as well is stated. That there are no clear algorithms for repeated use of the drug is shown. At the same time, possible options of this therapy in different clinical situations are given. Key words: levosimendan, cardiosurgery, heart failure

Investigation of numerical approaches to modeling large-scale turbulent vortex flows in the mode of vertical take-off and landing of an aircraft

The study considers the operation of an unmanned aerial vehicle in hovering mode over a flat landing platform. As a propulsion system, impellers are used, which are a system of a propeller rotating inside an air ring. The air ring is a body of revolution with an aerodynamic profile in cross section. The paper investigates the effect of unsteady interaction of vortex flows with the design of an aircraft by two alternative numerical methods, one of which is vortex-resolving. Numerical calculations are performed using the traditional turbulence modeling approach based on the averaged Navier–Stokes equations (RANS, Reynolds Averaged Navier–Stokes), where the turbulence is assumed to be isotropic, and the eddy-resolving Large Eddy Simulation method. The main feature of the latter is as follows: a turbulent flow is represented as the superposition of the motion of large-scale and small-scale turbulences. After discretizing the flow using a filtering operation, large-scale turbulence, which depends directly on the boundary conditions, is solved from the full Navier–Stokes equations. Small-scale turbulence has isotropic properties and is modeled similarly to semi-empirical RANS methods. The technique allows one to accurately calculate the vortex structure of any flow directly from the equations of motion using relatively low computing power, in contrast to the RANS models, which simulate the flow using a simplified mathematical model and can provide satisfactory accuracy only for a limited range of problems. The results indicate that eddy-resolving methods for modeling turbulence, in contrast to the methods based on averaged Navier–Stokes equations, make it possible to estimate the effect of aperiodic perturbations on the design of aircraft arising from the interaction of large eddies with each other and with the underlying surface. Such phenomena are accompanied by side impacts of a shock nature on the impeller rings, which can lead to loss of aircraft stability. Under conditions of a small propeller step, the use of an air ring results in a significant increase in the air flow passing through the rotor rotation loop, an increase in thrust due to the creation of flow circulation around the airfoil of the ring, and a decrease in the power on the propeller. Even though the effect of using an air ring disappears with a large incoming flow, this design is considered very promising for use on aircraft with vertical takeoff and landing. This mode of operation is the most energy-consuming and determines the greatest requirements for the lifting force of the power plant. The results of this work have demonstrated that numerical methods based on averaging the Navier–Stokes equations and the use of classical turbulence models of the k–ω or k–ε type, which are widely used in numerical modeling of propellers, in takeoff and landing modes fail to detect aperiodic unsteady phenomena associated with the interaction of large eddies, in contrast to eddy-resolving methods for modeling turbulence

SSR analysis of modern Russian potato varieties using DNA samples of nomenclatural standards

The N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR) is developing new approaches to documentation of national cultivars, taking into account recommendations of the International Code of Nomenclature for Cultivated Plants in parallel with methods of genetic certification. The nomenclatural standard of a particular cultivar represented by a herbarium specimen can be used as a reference for verifying authenticity and uniformity of cultivar specimens obtained from various sources. The verification requires fast and reliable methods for cultivar genotyping. This paper presents protocols for modified methods of DNA extraction, PCR-analysis and SSR-genotyping, which allow potato cultivars identification without the use of expensive reagent kits. A set of ten chromosome-specific microsatellite markers was used to study polymorphisms in 66 modern Russian potato cultivars, as well as in 11 pre-cultivars and breeding clones, represented by nomenclatural standards and voucher specimens, respectively. This subset of 77 specimens has demonstrated a high level of polymorphism in ten studied microsatellite loci. The SSR analysis identified 73 alleles; 7.3 alleles per locus were observed on average, the number of which varied from 3 (STG0025 locus) to 11 (locus StI046). The PIC values varied from 0.544 (STG0025 locus) to 0.836 (StI046 locus). The alleles, unique for this subset, were found at six studied loci. The high level of polymorphism at the SSR loci made it possible to unambiguously identify almost every cultivar, with the exception of the expected coincidence of microsatellite profiles of two cultivars, which are somaclonal variants. Using an optimized set of eight microsatellite markers, the genetic relationships of modern Russian potato cultivars were studied

Instability of coherent states of a real scalar field

We investigate stability of both localized time-periodic coherent states (pulsons) and uniformly distributed coherent states (oscillating condensate) of a real scalar field satisfying the Klein-Gordon equation with a logarithmic nonlinearity. The linear analysis of time-dependent parts of perturbations leads to the Hill equation with a singular coefficient. To evaluate the characteristic exponent we extend the Lindemann-Stieltjes method, usually applied to the Mathieu and Lame equations, to the case that the periodic coefficient in the general Hill equation is an unbounded function of time. As a result, we derive the formula for the characteristic exponent and calculate the stability-instability chart. Then we analyze the spatial structure of the perturbations. Using these results we show that the pulsons of any amplitudes, remaining well-localized objects, lose their coherence with time. This means that, strictly speaking, all pulsons of the model considered are unstable. Nevertheless, for the nodeless pulsons the rate of the coherence breaking in narrow ranges of amplitudes is found to be very small, so that such pulsons can be long-lived. Further, we use the obtaned stability-instability chart to examine the Affleck-Dine type condensate. We conclude the oscillating condensate can decay into an ensemble of the nodeless pulsons.Comment: 11 pages, 8 figures, submitted to Physical Review

Прогностическая значимость биомаркера NT-proBNP при хирургическом лечении аортального стеноза (пилотное исследование)

The objective was to study the relationship between the preoperative blood levels of the N-terminal segment of B-type natriuretic peptide precursor (NT-proBNP) and ultrasound and thermodilution indicators of cardiac function before and after on-pump surgery for aortic stenosis, as well as to evaluate the prognostic significance of the biomarker in relation to postoperative myocardial dysfunction.Materials and methods. The study involved 27 patients aged 57.7±2.5 years who underwent aortic valve replacement. NT-proBNP level was determined before surgery. The indicators of invasive hemodynamics and transesophageal echocardiography were analyzed at stages: I – after anesthesia induction, II – at the end of surgery. Correlation analysis, logistic regression and ROC analysis were used.Results. The preoperative NT-proBNP level was 2002.0 [540.8–4001.5] pg/ml. At I stage, NT-proBNP correlated with mean pulmonary artery pressure (rho = 0.468; p = 0.014), indices of left ventricular function (rho = –0.509; p = 0.007), end-diastolic and end-systolic volumes (rho = 0.737–0.757; p < 0.0001), as well as ejection fraction (rho = –0.556; p = 0.004) and area contraction fraction (rho = –0.783; p < 0.0001). At II stage, the level of NT-proBNP > 2000 pg/ml was a predictor of the left ventricular area contraction fraction < 50% (OR 1.0011, 95% CI 1.0002–1.0020, p = 0.028, AUC 0.799) , the left ventricular end-systolic area index > 9 cm2/m2 (OR 1.0007, 95% CI 1.0001–1.0013, p = 0.027, AUC 0.886), vasoactive-inotropic score > 10 (OR 1.0006, 95% CI 1.0001–1.0012, p = 0.032, AUC 0.876), duration of sympathomimetic therapy > 24 h (OR 1.0001, 95% CI 1.0000–1.0003, p = 0.049, AUC 0.889).Conclusions. NT-proBNP blood level was increased in 66.7% of patients with aortic stenosis before surgery. Moreover, the biomarker level directly correlates with the mean pulmonary artery pressure, the indices of end-diastolic and end-systolic volumes, end-diastolic and end-systolic areas of the left ventricle, and it inversely correlates with the left ventricular stroke work index, ejection fraction and left ventricular area contraction fraction. The preoperative NT-proBNP level was a predictor of the postoperative decrease to the pathological level of the ejection fractions and left ventricular area contraction, an increase in the left ventricular end-systolic area index, intensive and prolonged sympathomimetic therapy. Myocardial dysfunctions were most pronounced in patients with biomarker levels above 2000 pg/ml.Цель – изучить взаимосвязи дооперационного содержания в крови N-терминального отрезка предшественника натрийуретического пептида В-типа (NT-proBNP) с ультразвуковыми и термодилюционными показателями функции сердца до и после операции с искусственным кровообращением по поводу аортального стеноза, а также оценить прогностическую значимость биомаркера в отношении послеоперационной миокардиальной дисфункции.Материалы и методы. Обследовали 27 больных в возрасте 57,7±2,5 лет, которым выполнили протезирование аортального клапана. Уровень NT-proBNP определяли до операции. Показатели инвазивной гемодинамики и чреспищеводной эхокардиографии анализировали на этапах: I – после вводной анестезии, II – в конце операции. Использовали корреляционный анализ, логистическую регрессию и ROC-анализ.Результаты. Дооперационное содержание NT-proBNP составило 2002,0 [540,8–4001,5] пг/мл. На I этапе NT-proBNP коррелировал со средним давлением в легочной артерии (rho = 0,468; p = 0,014), индексами левожелудочковых ударной работы (rho = –0,509; p = 0,007), конечно-диастолического и конечно-систолического объемов (rho = 0,737–0,757; p < 0,0001), а также фракцией изгнания (rho = –0,556; p = 0,004) и фракцией сокращения площади левого желудочка (rho = –0,783; p < 0,0001). На II этапе значения NT-proBNP > 2000 пг/мл были предикторами фракции сокращения площади левого желудочка < 50% (ОШ 1,0011, 95%-ный ДИ 1,0002–1,0020, р = 0,028, ППК 0,799), индекса конечно-систолической площади левого желудочка > 9 см2/м2 (ОШ 1,0007, 95%-ный ДИ 1,0001–1,0013, р = 0,027, ППК 0,886), вазоактивно-инотропного индекса > 10 у. е. (ОШ 1,0006, 95%-ный ДИ 1,0001–1,0012, р = 0,032, ППК 0,876), длительности симпатомиметической терапии > 24 ч (ОШ 1,0001, 95%-ный ДИ 1,0000–1,0003, р = 0,049, ППК 0,889).Выводы. До операции у 66,7% больных с аортальным стенозом содержание NT-proBNP в крови повышено, причем уровень биомаркера прямо коррелирует со средним давлением в легочной артерии, индексами конечно-диастолического и конечно-систолического объемов, конечно-диастолической и конечно-систолической площадей левого желудочка и обратно – с индексом ударной работы, фракцией изгнания и фракцией сокращения площади левого желудочка. Дооперационный уровень NT-proBNP является предиктором послеоперационного снижения до патологического уровня фракций изгнания и сокращения площади левого желудочка, увеличения индекса конечно-систолической площади левого желудочка, интенсивной и длительной симпатомиметической терапии. В наибольшей степени выражены признаки дисфункции миокарда у больных уровнем биомаркера > 2000 пг/мл