Effect of an electric field on superfluid helium scintillation produced by alpha-particle sources

We report a study of the intensity and time dependence of scintillation produced by weak alpha particle sources in superfluid helium in the presence of an electric field (0 - 45 kV/cm) in the temperature range of 0.2 K to 1.1 K at the saturated vapor pressure. Both the prompt and the delayed components of the scintillation exhibit a reduction in intensity with the application of an electric field. The reduction in the intensity of the prompt component is well approximated by a linear dependence on the electric field strength with a reduction of 15% at 45 kV/cm. When analyzed using the Kramers theory of columnar recombination, this electric field dependence leads to the conclusion that roughly 40% of the scintillation results from species formed from atoms originally promoted to excited states and 60% from excimers created by ionization and subsequent recombination with the charges initially having a cylindrical Gaussian distribution about the alpha track of 60 nm radius. The intensity of the delayed component of the scintillation has a stronger dependence on the electric field strength and on temperature. The implications of these data on the mechanisms affecting scintillation in liquid helium are discussed.Comment: 17 pages, 23 figure

Deformations of the Retaining Structures Upon Deep Excavations in Moscow

Foundation trenches for the buildings having underground floors and vehicular traffic tunnels are excavated in Moscow in congested urban housing environment. A retaining structure is a “slurry wall” made of cast-in-place reinforced concrete), and “soil-mixed-wall”. Retaining structures of trenches are fastened with the help of anchors, metal tie-beams, struts or floor structures. During the monitoring performed at major Moscow construction sites with deep trenches the (NIIOSP) named after Gersevanov created a database on retaining structures deformations

The Effects of Mechanical Preload on Transmural Differences in Mechano-Calcium-Electric Feedback in Single Cardiomyocytes: Experiments and Mathematical Models

Transmural differences in ventricular myocardium are maintained by electromechanical coupling and mechano-calcium/mechano-electric feedback. In the present study, we experimentally investigated the influence of preload on the force characteristics of subendocardial (Endo) and subepicardial (Epi) single ventricular cardiomyocytes stretched by up to 20% from slack sarcomere length (SL) and analyzed the results with the help of mathematical modeling. Mathematical models of Endo and Epi cells, which accounted for regional heterogeneity in ionic currents, Ca2+ handling, and myofilament contractile mechanisms, showed that a greater slope of the active tension–length relationship observed experimentally in Endo cardiomyocytes could be explained by greater length-dependent Ca2+ activation in Endo cells compared with Epi ones. The models also predicted that greater length dependence of Ca2+ activation in Endo cells compared to Epi ones underlies, via mechano-calcium-electric feedback, the reduction in the transmural gradient in action potential duration (APD) at a higher preload. However, the models were unable to reproduce the experimental data on a decrease of the transmural gradient in the time to peak contraction between Endo and Epi cells at longer end-diastolic SL. We hypothesize that preload-dependent changes in viscosity should be involved alongside the Frank–Starling effects to regulate the transmural gradient in length-dependent changes in the time course of contraction of Endo and Epi cardiomyocytes. Our experimental data and their analysis based on mathematical modeling give reason to believe that mechano-calcium-electric feedback plays a critical role in the modulation of electrophysiological and contractile properties of myocytes across the ventricular wall. © Copyright © 2020 Khokhlova, Konovalov, Iribe, Solovyova and Katsnelson.AAAA-A18-118020590031-8Russian Foundation for Basic Research, RFBR: 18-01-00059Russian Science Foundation, RSF: 18-74-10059Funding. Wet experiments were supported by the Russian Science Foundation (#18-74-10059). The development of mouse ventricular cardiomyocyte model was supported by the Russian Foundation for Basic Research (#18-01-00059), IIF UrB RAS theme (AAAA-A18-118020590031-8), and by RF Government Act #211 of March 16, 2013 (agreement 02.A03.21.0006)

Drift of scrollwaves in a mathematical model of a heterogeneous human heart left ventricle

Rotating spiral waves of electrical excitation underlie many dangerous cardiac arrhythmias. The heterogeneity of myocardium is one of the factors that affects the dynamics of such waves. In this paper, we present results of our simulations for scroll wave dynamics in a heterogeneous model of the human left ventricle with analytical anatomically based representation of the geometry and anisotropy. We used a set of 18 coupled differential equations developed by ten Tusscher and Panfilov (TP06 model) which describes human ventricular cells based on their measured biophysical properties. We found that apicobasal heterogeneity dramatically changes the scroll wave dynamics. In the homogeneous model, the scroll wave annihilates at the base, but the moderate heterogeneity causes the wave to move to the apex and then continuously rotates around it. The rotation speed increased with the degree of the heterogeneity. However, for large heterogeneity, we observed formation of additional wavebreaks and the onset of complex spatio-temporal patterns. Transmural heterogeneity did not change the dynamics and decreased the lifetime of the scroll wave with an increase in heterogeneity. Results of our numerical experiments show that the apex may be a preferable location of the scroll wave, which may be important for development of clinical interventions. © 2020 by the authors.AAAA-A18-118020590031-8Russian Foundation for Basic Research, RFBR: 18-29-13008Russian Science Foundation, RSF: 14-35-00005Ural Federal University, UrFUP.K., S.P., O.S., and A.V.P. were funded by the Russian Science Foundation (project 14-35-00005). A.V.P., P.K., and O.S. were funded by the Russian Foundation for Basic Research (#18-29-13008). A.V.P. and O.S. were funded by RF Government Act #211 of 16 March 2013 (agreement 02. A03.21.0006). P.K. and O.S. work was carried out within the framework of the IIF UrB RAS theme No. AAAA-A18-118020590031-8. A.V.P. and H.D. were partially funded by BOF Ghent University. Simulations were performed at the supercomputer Uran of Institute of Mathematics and Mechanics (Ekaterinburg, Russia) and at the supercomputer of Ural Federal University (Ekaterinburg, Russia)

Test beam studies of the TRD prototype filled with different gas mixtures based on Xe, Kr, and Ar

Towards the end of LHC Run1, gas leaks were observed in some parts of the Transition Radiation Tracker (TRT) of ATLAS. Due to these leaks, primary Xenon based gas mixture was replaced with Argon based mixture in various parts. Test-beam studies with a dedicated Transition Radiation Detector (TRD) prototype were carried out in 2015 in order to understand transition radiation performance with mixtures based on Argon and Krypton. We present and discuss the results of these test-beam studies with different active gas compositions.Comment: 5 pages,12 figures, The 2nd International Conference on Particle Physics and Astrophysics (ICPPA-2016); Acknowledgments section correcte

Some results of test beam studies of Transition Radiation Detector prototypes at CERN

Operating conditions and challenging demands of present and future accelerator experiments result in new requirements on detector systems. There are many ongoing activities aimed to develop new technologies and to improve the properties of detectors based on existing technologies. Our work is dedicated to development of Transition Radiation Detectors (TRD) suitable for different applications. In this paper results obtained in beam tests at SPS accelerator at CERN with the TRD prototype based on straw technology are presented. TRD performance was studied as a function of thickness of the transition radiation radiator and working gas mixture pressure

The environment effect on operation of in-vessel mirrors for plasma diagnostics in fusion devices

First mirrors will be the plasma facing components of optical diagnostic systems in ITER. Mirror surfaces will undergo modification caused by erosion and re-deposition processes [1,2]. As a consequence, the mirror performance may be changed and may deteriorate [3,4]. In the divertor region it may also be obscured by deposition [5-7]. The limited access to in-vessel components of ITER calls for testing the mirror materials in present day devices in order to gather information on the material damage and degradation of the mirror performance, i.e. reflectivity. A dedicated experimental programme, First Mirror Test (FMT), has been initiated at the JET tokamak within the framework Tritium Retention Studies (TRS).Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France).Submitted by B. Schunke on behalf of V. Voytseny

Assessment of potential winter hardiness in winter bread wheat cultivars and genotypes by analyzing autofluorescence in seedling tissues

Background. Winter crops are the most productive component of agricultural biocenoses. In Russia, winter wheat suffers the greatest losses in winter, so a search for traits marking high or low winter hardiness in autumn-sown genotypes, including improved cultivars, is needed to assess their potential for overwintering. One of such markers of high winter hardiness is an increased lignin content in plant tissues. The terminal enzyme in the phenylpropanoid pathway of metabolism, wherein lignin components are formed, is cinnamyl-alcohol dehydrogenase (CAD, EC 1.1.1.195). In plants, the CAD enzyme is one of the links in the aromatic metabolism, which generates, in addition to lignin, a number of aromatic compounds, such as lignans, aromatic glycosides, etc. Many of these compounds, like lignin, contain chromophore groups and are capable of autofluorescence. Correlations of the genotypes that incorporate CAD1-F with overwintering are studied in this work.Materials and methods. The winter bread wheat cultivars ‘Zitnica’ (Yugoslavia) and ‘Novosibirskaya 9’ (ICG SB RAS, Russia), contrasting in winter hardiness and CAD isozyme spectra, their hybrids, and 28 improved winter cultivars developed in Krasnodar were selected for the study. Fluorescence analysis of 28 winter wheat cultivars was also performed. Correlation coefficients between fluorescence and frost tolerance were calculated using the results of the analysis of 7 most contrasting cultivars.Conclusions. The tested winter bread wheat genotypes demonstrated the interplay between CAD1-F and successful overwintering: a correlation was found in the genotypes carrying the 00 CAD1-F allele with higher percentage of overwintered plants. This dependence was not observed in every season. The analysis of seedling sections for fluorescence can also be used for preliminary assessment of winter tolerance in winter bread wheat under laboratory conditions

Organoleptic and physical and chemical parameters of Nubian goats’ milk at mixed infection with gastrointestinal nematodes from the suborder Strongylata

The purpose of the research is to determine the species composition of nematodes from the suborder Strongylata and to study organoleptic and physical and chemical parameters of the Nubian goats’ milk at strongylatoses of the digestive tract. Materials and methods. The study subjects were lactating Nubian goats aged 3 to 5 years from private farms in the Moscow Region. A total of 37 animals were examined. Faeces were studied by flotation methods per Fülleborn and KotelnikovKhrenov. To determine the species composition, partial helminthological dissections per K. I. Skryabin were used. In the infected animals from the experimental and control groups, organoleptic and physical and chemical milk parameters were studied prior to and after therapeutic measures using an anthelmintic with the active ingredient fenbendazole at a dose of 5 mg/kg. The deworming effectiveness was determined by the control test. Physical and chemical milk parameters were determined using an automatic Klever-2 milk analyzer, and organoleptic parameters were determined according to common methods pursuant to the effective GOST.Results and discussion. The lactating Nubian goats infected with gastrointestinal strongylates on the Moscow Region private farms amounted to 100% in the Podolsk Urban Okrug, and 88.2% in the Voskresensk Urban Okrug. The species composition was represented by 8 species, namely, Haemonchus сontortus, Ostertagia ostertagi, Trichostrongylus axei, T. colubriformis, Nematodirus spathiger, N. filicollis, Cooperia оvina, and Bunostomum trigonocephalum. In the pre- and postdeworming milk studies, the organoleptic parameters corresponded to the effective GOST in appearance, texture, color and smell; the sweetish taste was only absent after deworming in the experimental goats. Gastrointestinal nematodes from the suborder Strongylata did not affect the organoleptic parameters of milk. However, the pre- and posttreatment weight fraction of fat changed from 2.90±0.30 to 5.40±0.22% in the experimental group