Analysis of Anisotropic Transverse Flow in Pb–Pb Collisions at 40A GeV in the NA49 Experiment

Anisotropic transverse flow is one of the most important observables in the study of ultra-relativistic nucleus-nucleus collisions. Detector acceptance non-uniformity in the transverse plane introduces substantial bias in the flow analysis dictating the need for specific corrections. The results of flow analysis in Pb-Pb collisions at the beam energy of 4

Optimal estimates of the diffusion coefficient of a single Brownian trajectory

Modern developments in microscopy and image processing are revolutionizing areas of physics, chemistry and biology as nanoscale objects can be tracked with unprecedented accuracy. The goal of single particle tracking is to determine the interaction between the particle and its environment. The price paid for having a direct visualization of a single particle is a consequent lack of statistics. Here we address the optimal way of extracting diffusion constants from single trajectories for pure Brownian motion. It is shown that the maximum likelihood estimator is much more efficient than the commonly used least squares estimate. Furthermore we investigate the effect of disorder on the distribution of estimated diffusion constants and show that it increases the probability of observing estimates much smaller than the true (average) value.Comment: 8 pages, 5 figure

Natural attenuation of Fukushima-derived radiocesium in soils due to its vertical and lateral migration

Processes of vertical and lateral migration lead to gradual reduction in contamination of catchment soil, particularly its top layer. The reduction can be considered as natural attenuation. This, in turn, results in a gradual decrease of radiocesium activity concentrations in the surface runoff and river water, in both dissolved and particulate forms. The purpose of this research is to study the dynamics of Fukushima-derived radiocesium in undisturbed soils and floodplain deposits exposed to erosion and sedimentation during floods. Combined observations of radiocesium vertical distribution in soil and sediment deposition on artificial lawn-grass mats on the Niida River floodplain allowed us to estimate both annual mean sediment accumulation rates and maximum sedimentation rates corresponding to an extreme flood event during Tropical Storm Etau, 6-11 September 2015. Dose rates were reduced considerably for floodplain sections with high sedimentation because the top soil layer with high radionuclide contamination was eroded and/or buried under cleaner fresh sediments produced mostly due to bank erosion and sediments movements. Rate constants of natural attenuation on the sites of the Takase River and floodplain of Niida River was found to be in range 0.2-0.4 year-1. For the site in the lower reach of the Niida River, collimated shield dose readings from soil surfaces slightly increased during the period of observation from February to July 2016. Generally, due to more precipitation, steeper slopes, higher temperatures and increased biological activities in soils, self-purification of radioactive contamination in Fukushima associated with vertical and lateral radionuclide migration is faster than in Chernobyl. In many cases, monitored natural attenuation along with appropriate restrictions seems to be optimal option for water remediation in Fukushima contaminated areas

Spatio-Temporal Assessment of Gully Erosion in the Zone of Intensive Agriculture in the European Part of Russia

© 2018, Pleiades Publishing, Ltd. Using the method of mapping by high resolution satellite imagery mapping, a study was made of the key areas which are located in the southern part of the forest, forest-steppe and steppe zones of Tatarstan and of Orenburg, Saratov and Voronezh oblasts. Two key indicators were determined: the gully length density and gully head density within the basins; results of the investigation were used in compiling respective maps in vector format. It is established that the density of the gully length in the basins varies over the range from 0 to 0.5 km/km2 (from the absence of gullies to strong gully erosion), and the density of gully heads from 0 to 3 units/km2. The slope type of gullies is dominant in all basins (about 80%), while the coastal and bottom types have approximately the same proportion (14 and 10%, respectively). Using methods of mathematical statistics we determined a high directly proportional dependence of the indicators of the contemporary gully network on the level of ploughness of the basins and the mean annual precipitation amount, and an indirectly proportional dependence on the level of sodding. An abrupt reduction in gullying indicators was determined. It was found that among the chief reasons behind an abrupt reduction in the gullies to date is a decrease of the rate of agricultural development, with an additional factor, namely, a dramatic decrease in surface runoff down the arable slopes during spring snowmelt caused by climate warming. It is concluded that that a significant part of the gully forms in the study area is currently inactive and massively passes into the balka stage

Mapping assessment of gully erosion in the east of the Russian plain

Detailed-scale mapping of gully network based on the river basin approach was carried out for the eastern part of the Russian Plain using remote sensing data. The total number of selected catchments was 4575, average catchment area - 37.5 km 2 . GIS map of regions with different degree of gully dissection was created based on the produced geospatial database on the gulliy density in elementary catchments. Eight types of gully dissection were recognized in the studied area. Average gully density was estimated at 0.21 km/km 2 , with local highs up to 2-2.3 km/km 2 in some basins between the rivers Volga and Tsivil, at the right bank of the lower Kama and in the upper part of the right side of the Sviyaga River valley. Strong gully dissection (0.5-1.0 km/km 2 ) is the dominating category characteristic for 28.3% of elementary catchments. More than a quarter of all the elementary catchments located in the southern taiga subzone of Udmurt Republic and forested part of Mari El Republic demonstrate the absence or sporadic occurrence of gullies. The interpretation of repeated space and aerial images for two time intervals allowed to determine the changes of gully length in the north-western part of studied area at the end of the XX century. It was found that during the 23-25-year time interval, the total length of gully network in the Udmurt Republic decreased by 2%. Decline of gully erosion activity was observed mainly in the southern half of Udmurtia, which is marked by the higher degree of gully dissection. Rise of gully erosion exhibited by the appearance of new gullies on the previously non-eroded slopes was found in the northern part ofUdmurtiaandinthe Kilmez' River basin

Formation of quasi-periodic nano- and microstructures on silicon surface under IR and UV femtosecond laser pulses

Quasi-periodic nano- and microstructures have been formed on silicon surface using IR ( λ ≈ 744 nm) and UV ( λ ≈ 248 nm) femtosecond laser pulses. The influence of the incident laser fluence and the number of pulses on the structured surface topology has been investigatedyesBelgorod State Universit

Alternative proof for the localization of Sinai's walk

We give an alternative proof of the localization of Sinai's random walk in random environment under weaker hypothesis than the ones used by Sinai. Moreover we give estimates that are stronger than the one of Sinai on the localization neighborhood and on the probability for the random walk to stay inside this neighborhood

Transverse spin dynamics in a spin-polarized Fermi liquid

The linear equations for transverse spin dynamics in weakly polarised degenerate Fermi liquid with arbitrary relationship between temperature and polarization are derived from Landau-Silin phenomenological kinetic equation with general form of two-particle collision integral. The temperature and polarization dependence of the spin current relaxation time is established. It is found in particular that at finite polarization transverse spin wave damping has a finite value at T=0. The analogy between temperature dependences of spin waves attenuation and ultrasound absorption in degenerate Fermi liquid at arbitrary temperature is presented. We also discuss spin-polarized Fermi liquid in the general context of the Fermi-liquid theory and compare it with "Fermi liquid" with spontaneous magnetization.Comment: 10 page

Mapping and spatial-temporal assessment of gully density in the Middle Volga region, Russia

© 2018 John Wiley & Sons, Ltd. A large-scale mapping of gully density was carried out for the Middle Volga region of the Russian Plain (188 000 km2) based on the interpretation of aerial photographs (scale 1:17 000; surveys undertaken during 1956–1970). In addition, spatial-temporal dynamic of gully density were assessed for some parts of the study area (the Udmurt Republic and the Mesha and Ulema River basins of Tatarstan), based on the interpretation of aerial photographs (survey 1986–1991) and high resolution satellite images (2012–2015). Information on factors potentially controlling gully formation and development were collected and a geographic information system (GIS) analysis was conducted. Results show the strong development of gullies in the study area over the 1956–1970 period with an average gully density of 0.21 km km−2. For the Udmurt region, we found that gully densities varied little in the period 1956–1986, during which the total active gully length reduced with only 2%. This period was characterized by low variable climatic conditions and a stable fraction of arable land with a relatively continuous crop rotation system. However, gully dynamics seems to have changed more strongly during recent decades. We found a strong (order of magnitude) reduction in active gully density for the period 2010–2015 as compared to 1986–1991. The main reason for this is likely the increasing winter air temperatures. This leads to a significant reduction in surface runoff during spring as a result of snowmelt. Nonetheless, in some regions (i.e. the Udmurt Republic in the taiga zone), the abandonment of arable land after 1991 likely plays a significant role. Likewise, a decline in the frequency of extreme rainfall events (> 50 mm) may have played a role. All of these factors contribute to a reduction of surface runoff to the gullies and their subsequent stabilization. © 2018 John Wiley & Sons, Ltd

Effects of land use and climate changes on small reservoir siltation in the agricultural belt of European Russia

Small reservoirs of agriculture-dominated areas experience severely increased sediment input caused by soil erosion on cultivated slopes, also accompanied at some locations by gully erosion. This causes rapid decrease of the reservoir water storage and shortened periods of functioning. In this paper we discuss several examples of the 137Cs-based short-term siltation chronology of small reservoirs located in different landscape zones within the agricultural belt of European Russia. From two to four time marks could have been established in 137Cs depth distribution curves constructed from detailed depth-incremental sampling of reservoir infill sediment, allowing reconstruction of sediment microstratigraphy and deposition rates. In combination with other independent information sources this provides insight on the relative importance of recent land use changes and climatic variability in controlling sediment delivery within small agriculture-dominated fluvial systems. In combination with sediment redistribution studies, it has become possible to construct closed sediment budgets for catchments of several reservoirs and make a quantitative assessment of sediment delivery variability. Such information is important for appropriate design and management of small agricultural reservoirs in Russia. Copyright © 2013 IAHS Press