Search

Safe navigation in uneven terrains is an important problem in robotic research. In this paper we propose a 2.5D navigation system which consists of elevation map building, path planning and local path following with obstacle avoidance. For local path following we use Model Predictive Path Integral (MPPI) control method. We propose novel cost-functions for MPPI in order to adapt it to elevation maps and motion through unevenness. We evaluate our system on multiple synthetic tests and in a simulated environment with different types of obstacles and rough surfaces.

Domestication of horses fundamentally transformed long-range mobility and warfare1. However, modern domesticated breeds do not descend from the earliest domestic horse lineage associated with archaeological evidence of bridling, milking and corralling2–4at Botai, Central Asia around 3500 bc3. Other longstanding candidate regions for horse domestication, such as Iberia5and Anatolia6, have also recently been challenged. Thus, the genetic, geographic and temporal origins of modern domestic horses have remained unknown. Here we pinpoint the Western Eurasian steppes, especially the lower Volga-Don region, as the homeland of modern domestic horses. Furthermore, we map the population changes accompanying domestication from 273 ancient horse genomes. This reveals that modern domestic horses ultimately replaced almost all other local populations as they expanded rapidly across Eurasia from about 2000 bc, synchronously with equestrian material culture, including Sintashta spoke-wheeled chariots. We find that equestrianism involved strong selection for critical locomotor and behavioural adaptations at the GSDMCand ZFPM1genes. Our results reject the commonly held association7between horseback riding and the massive expansion of Yamnaya steppe pastoralists into Europe around 3000 bc8,9driving the spread of Indo-European languages10. This contrasts with the scenario in Asia where Indo-Iranian languages, chariots and horses spread together, following the early second millennium bcSintashta culture11,12.

Abstract: The problem of finding the least number of variables of a first-order formula expressing the statement that an input-graph contains a subgraph isomorphic to a given pattern-graph is studied. Input-graphs of sufficiently high connectivity are considered. This problem has previously been solved for all pattern-graphs on four vertices except the simple cycle and the diamond graph. In the paper, this number is found for the two remaining graphs.

Different reactivity of homologous disulfides toward Pd2+was previously reported: stepwise complexation to Pd2+for l-cystine and cystamine ligands, while for dl-homocystine and 3,3′-dithiodipropionic acid, disulfide’s disproportionation toward thiolate and sulfinic acid complexes is observed. The disulfide/thiolate interconversion of four different disulfide ligands in the presence of nonredox metal cation Pd2+in aqueous solution has been computationally investigated. We see this different reactivity in different capacities of considered homologous disulfides to stabilize forming S,S′-binuclear complexes, which are believed to be key intermediates toward interconversion products. We thus devise a theoretical model that rationalizes experimentally observed phenomenon of disulfides different reactivity toward nonredox transition metal cation Pd2+.

Predicting mechanisms and rates of nonadiabatic spin-dependent processes including photoinduced intersystem crossings, thermally activated spin-forbidden reactions, and spin crossovers in metal centers is a very active field of research. These processes play critical roles in transition-metal-based and metalloenzymatic catalysis, molecular magnets, light-harvesting materials, organic light-emitting diodes, photosensitizers for photodynamic therapy, and many other applications. Therefore, accurate modeling of spin-dependent processes in complex systems and on different time scales is important for many problems in chemistry, biochemistry, and materials sciences.

We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We determine the expected sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron-star systems, which are considered the most promising for multi-messenger astronomy. The ability to localize the sources of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and 90% credible regions can be as large as thousands of square degrees when only two sensitive detectors are operational. Determining the sky position of a significant fraction of detected signals to areas of 5 deg2to 20 deg2will require at least three detectors of sensitivity within a factor of ∼ 2 of each other and with a broad frequency bandwidth. Should the third LIGO detector be relocated to India as expected, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.

We present a nonadiabatic statistical theory (NAST) package for predicting kinetics of spin-dependent processes, such as intersystem crossings, spin-forbidden unimolecular reactions, and spin crossovers. The NAST package can calculate the probabilities and rates of transitions between the electronic states of different spin multiplicities. Both the microcanonical (energy-dependent) and canonical (temperature-dependent) rate constants can be obtained. Quantum effects, including tunneling, zero-point vibrational energy, and reaction path interference, can be accounted for. In the limit of an adiabatic unimolecular reaction proceeding on a single electronic state, NAST reduces to the traditional transition state theory. Because NAST requires molecular properties at only a few points on potential energy surfaces, it can be applied to large molecular systems, used with accurate high-level electronic structure methods, and employed to study slow nonadiabatic processes. The essential NAST input data include the nuclear Hessian at the reactant minimum, as well as the nuclear Hessians, energy gradients, and spin–orbit coupling at the minimum energy crossing point (MECP) between two states. The additional computational tools included in the NAST package can be used to extract the required input data from the output files of electronic structure packages, calculate the effective Hessian at the MECP, and fit the reaction coordinate for more advanced NAST calculations. We describe the theory, its implementation, and three examples of application to different molecular systems.

De novo assembly is a widely used methodology in bioinformatics. However, the conventional short-read-based de novo assembly is incapable of reliably reconstructing the large-scale structures of human genomes. Recently, a novel optical label-based technology has enabled reliable large-scale de novo assembly. Despite its advantage in large-scale genome analysis, this new technology requires a more computationally intensive alignment algorithm than its conventional counterpart. For example, the runtime of reconstructing a human genome is on the order of 10,000 hours on a sequential CPU. Therefore, in order to practically apply this new technology in genome research, accelerated approaches are desirable. In this article, we present three different accelerated approaches, multicore CPU, GPU, and FPGA. Against the sequential software baseline, our multicore CPU design achieved an 8.4× speedup, while the GPU and FPGA designs achieved 13.6× and 115× speedups, respectively. We also discuss the details of the design space exploration of this new assembly algorithm on these three different devices. Finally, we compare these devices in performance, optimization techniques, prices, and design efforts.

We have demonstrated experimentally and numerically the possibility of controlling parameters of plasma channels formed during filamentation of a femtosecond laser pulse by introducing astigmatism in the laser beam wavefront. It is found that weak astigmatism increases the length of the plasma channel in comparison with the case of aberration-free focusing and that strong astigmatism can cause splitting of the plasma channel into two channels located one after another on the filament axis.

The results of experimental and theoretical study of the self-action of femtosecond optical vortices in the region of anomalous group velocity dispersion in fused silica and fluorides are presented. Multiple filamentation of an axially asymmetric annular beam with a phase dislocation of topological charge m= 1 at a wavelength of 1800 nm in a LiF crystal is investigated. It is found that for the experimentally recorded intensity profile of a vortex beam with two maxima on the diameter, the critical self-focusing power is approximately two times larger than the critical power of a unimodal Gaussian beam. In pulses with supercritical power in the vicinity of the intensity maxima, two coupled filaments, separated by a phase dislocation, are formed on the annular profile of the optical vortex, which prevents energy exchange during their formation. The length of vortex-beam plasma channels in a single pulse is found to be about 300 μm at a diameter of about 2 μm, which is close to the characteristics of plasma channels in a Gaussian beam.

The filamentation of IR and UV laser pulses has been studied numerically and experimentally for different initial beam focusing geometries, and linear electron density profiles along the plasma channel of filaments have been obtained. The results demonstrate that changes in laser beam focusing have a stronger effect on filament and plasma channel parameters for UV radiation than for IR radiation. Focusing causes individual high fluence regions produced by refocusing to merge to form a continuous extended filament with a continuous plasma channel.

The interaction of two coherent femtosecond laser pulses, propagating at a small angle with respect to each other in a sapphire crystal in the filamentation regime, has been investigated numerically and experimentally. Distributions of the fluence and free-electron density in the laser-plasma channels formed in the crystal are obtained. Additional filaments are found to form outside the plane of initial pulse propagation.

Abstract: The effect of the natural factors (solar activity) on the long-term variations of global temperatures has been analyzed based on studying the borehole thermal regime in a time interval of 1000 years ago. It has been indicated that the temperatures started rising about 500 rather than 150 years ago as adherents of the anthropogenic impact on climate consider. The temperature maximum, the amplitude of which is larger than the present-day rise of temperature, is determined about 1000 years ago. The appearance of this maximum corresponds to the time interval of a long-term increase in solar activity according to the data of the 14C and 10Be cosmogenic isotopes. The stabilization of the global temperature in the last decades at a constant increase in the amount of greenhouse gases in the atmosphere contradicts the concept, according to which an increase in the global temperature in the last decades is only explained by the anthropogenic impact.

Abstract: The most reliable pattern of climate changes is obtained using data of instrumental observations at the network of meteorological stations. However, the series of such data have short timescales (about 150 years). Indirect data from natural archives make it possible to judge specific features of climate changes in the more distant past. In contrast to indirect methods, when data are related to temperature through statistical correlations with air temperature, the borehole geothermal method makes it possible to directly determine the surface air temperature. The reconstructions of the temperature obtained using different indirect data for the Northern Hemisphere have been compared with the surface air temperature reconstructions based on the data of borehole thermometry and solar activity variations, and the possibilities of using the method in order to reconstruct long-term trends in climate changes have been indicated.

Abstract: The climatic variability in the past on the time scales from several tens to several hundreds of million years has been analyzed based on the paleoclimatic data with a time resolution of several years (the variations in the fossil tree ring widths, varve). The revealed periodicity in the climatic parameters correlates with the observed solar activity cyclicity, which indicates that this periodicity effectively influences climate changes independently of differences in the climatic conditions in the considered interval.

Abstract: Such high-resolution indirect data on solar activity as the 14C and 10Be cosmogenic isotopes have been considered. The long-term solar activity cyclicity during the last millennium with periods of approximately 90 and 210 years, which can be related to substantial climatic warming and cooling events in this millennium, has been established based on an analysis of these data. It has been indicated that long-term recent climate warming can result from the effect of the ∼90- and ∼210-year solar cycles on the climatic system, which is characterized by the nonlinear dynamics.

Abstract: Paleoclimatological reconstructions of temperature of the Earth’s Northern Hemisphere for the last thousand years have been studied using the up-to-date methods of statistical analysis. It has bee indicated that the quasisecular (a period of 60–130 years) cyclicity, which is observed in the climate of the Earth’s Northern Hemisphere, has a bimodal structure, i.e., being composed of the 60–85 and 85–130 year periodicities. The possible relation of the quasisecular climatic rhythm to the corresponding Gleissberg solar cycle has been studied using the solar activity reconstructions performed with the help of the solar paleoastrophysics methods.

Abstract: The most reliable data on a change in the intensity of cosmic rays and geomagnetic field on large time scales have been analyzed, and the relations between changes in these processes and climate during the last 1.5 Myr have been studied. An analysis indicated that the climate of the Earth is affected by changes in the Earth’s orbit parameters and geomagnetic dipole values; however, the climate responds to these changes with a delay of 10 kyr and immediately, respectively. In this case about two thirds of the effect of eccentricity on 18O is implemented via an intermediate chain: virtual axial dipole moment, changes in which can be related to changes in eccentricity. Thus, an analysis of the accumulated data on the processes, proceeding in the Earth’s atmosphere during the interaction with cosmic rays on the scales of several years to several hundreds of thousand years, indicates that the cosmophysical factor of influence on climate cannot be rejected. To make the conclusion more convincing, it is necessary to collect data for the studied time interval in a much wider region, to more accurately date samples, and to study the response of the climatic system to the external influence.

Abstract: Ethane aromatization on gallium-and platinum-modified pentasil zeolites (ZSM-5) with different framework constitutions was studied. The optimal zeolite composition and reaction conditions were determined and the synergistic effect of the promoters was revealed. The dependence of the catalyst activity on the SiO2/Al2O3 molar ratio was established. The highest yield of aromatic hydrocarbons (∼30%) and the highest selectivity for their formation from ethane (∼63%) were attained on the (2%Ga–0.3%Pt)/HZSM-5 bimetallic catalyst having SiO2/Al2O3 = 30.

Abstract: An analysis of the paleomagnetic characteristics of the bottom sediments taken in 2000 in the northern Barents Sea for the first time revealed the Gothenburg geomagnetic field excursion (13 000–12 000 years ago) at the time boundary of the transition from the glacial period to the recent warm epoch (the Holocene). The obtained data confirm the excursion complex structure: the presence of two successive time intervals of variations in the geomagnetic field inclination. An increase in the magnetic susceptibility and natural remanent magnetization of the samples at the above boundary and about 15 000 years ago indicates that the magnetic parameters of the sediments respond to climate changes in the environment in this time interval.

Abstract: Long-period variations in the cyclonic activity at middle and subpolar latitudes of the North Atlantic are studied on the basis of the data from the MSLP archive of the surface pressure (Climatic Research Unit, UK) for 1874–1995. It has been found that in the cold half year (the period of the most intense formation and development of extra-tropical cyclones) in the studied region, oscillations of the surface pressure with periods close to the main periods of solar activity (∼80 and ∼11 years) are observed. The obtained results make it possible to assume that solar activity and related variations in the galactic cosmic rays are one of the factors influencing the intensity of cyclonic processes at midlatitudes on the time scales of ∼10 to ∼100 years.

Abstract: A joint analysis of paleodata on variations in cosmic ray fluxes, solar activity, geomagnetic field, and climate during the period from ∼10000 to ∼100000 years ago has been performed. Data on the time variations in the concentration of 14C and 10Be cosmogenic isotopes, which are generated in the Earth’s atmosphere under the action of cosmic ray fluxes modulated by solar activity and geomagnetic field variations, were used to detect variations in solar activity and the geomagnetic dipole. Information about climate changes has been obtained mainly from variations in the concentration of stable isotopes in the natural archives. A performed analysis indicates that the variations in cosmic ray fluxes under the action of variations in the geomagnetic field and solar activity are apparently one of the most effective natural factors of long-term climate changeability on a large time scale.

We report on a search for gravitational-wave bursts in data from the three LIGO interferometric detectors during their third science run. The search targets sub-second bursts in the frequency range 100-1100 Hz for which no waveform model is assumed and has a sensitivity in terms of the root-sum-square(rss) strain amplitude of hrss~ 10?20Hz?1/2. No gravitational-wave signals were detected in the eight days of analysed data.

Direct and indirect data on variations in cosmic rays, solar activity, geomagnetic dipole moment, and climate from the present to 10–12ka ago (the Holocene Epoch), registered in different natural archives (tree rings, ice layers, etc.), have been analyzed. The concentration of cosmogenic isotopes, generated in the Earth’s atmosphere under the action of cosmic ray fluxes and coming into the Earth archives, makes it possible to obtain valuable information about variations in a number of natural processes. The cosmogenic isotopes 14C in tree rings and 10Be in ice layers, as well as cosmic rays, are modulated by solar activity and geomagnetic field variations, and time variations in these concentrations gives information about past solar and geomagnetic activities. Since the characteristics of natural reservoirs with cosmogenic 14C and 10Be vary with climate changes, the concentrations of these isotopes also inform about climate changes in the past. A performed analysis indicates that cosmic ray flux variations are apparently the most effective natural factor of climate changes on a large time scale.

Solid-state modification was used to prepare zinc-containing zeolite catalysts based on pentasils with different framework SiO2/Al2O3ratios. The catalysts were studied by X-ray diffraction analysis and IR spectroscopy. The activity and selectivity of the Zn—pentasil systems prepared by the solid-state modification and impregnation methods were compared in the aromatization of ethane. The active and stable zeolite catalysts modified by transition metal ions can be obtained by the topochemical method.

The kinetics of A1H3decomposition were studied as a function of temperature and hydrogen pressure. Analysis of the experimental data in the formal heterogeneous kinetic approach suggests that the rate of the process is limited by the breaking of Al-H bonds.

1.On high-silica zeolites of the pentasil family, xylenes are converted to isomerization products with high selectivity. In the presence of wider-pore zeolites, the isomerization is accompanied with a considerable degree of disproportionation, the contribution of which increases with increasing diameter of the zeolite pores.2.The hydroxyl cover in the pentasils has a far higher thermal stability than in the mordenites; and as a consequence, the pentasils retain high catalytic activities even when heat-treated at 700°C.3The acidic centers of zeolites of the pentasil and mordenite types are similar in heats of ammonia adsorption and in their specific activity in xylene conversion.

1.The introduction of 0.3% vanadium into decationized SHSZ increases the overall yield of aromatic products in isobutylene conversion at 320°C by a factor of 1.5. This effect is considerably less pronounced at 500°C.2.Increases of the vanadium concentration in the zeolite lead to higher contents of p-xylene in the C8-alkylbenzene fraction.

1.Mordenite catalysts dealuminated by 50% show the highest activity for the isomerization of o-xylene.2.At low degree of conversion, the ratio of the disproportionation and isomerization rates of o-xylene is independent of the aluminum content of the mordenite framework, and the closer one approaches equilibrium, the more the disproportionation contribution increases with increasing degree of dealumination.

Capture and reversible high-temperature chemisorption of hydrogen is observed on catalysts containing reduced V2O5 supported on MgO and Al2O3 which have been heated to 500°C. The amount of hydrogen taken up in chemisorption varies with the concentration of V2O5 and the nature of the carrier, the latter factor determining the relative ease of desorption.

1.The Bi, Sn, Sb, and In oxides are inactive as catalysts for the aromatization of isobutylene. The Zn, Ti, Th, and V oxides are slightly active in this reaction, but in the case of the Ti and Zn oxides the liquid reaction products contain mainly p-xylene (respectively 80.8 and 63.2%).2.The catalysts, obtained by depositing V2O3 on Al2O5, Al2O3(F), and SiO2, have a high activity, in which connection the main reaction products are xylenes, the amount of which in the catalyzates is respectively 76.2, 75.4, and 93.4%. The ratio between the individual reaction products and, in particular, between the C8 aromatic hydrocarbons, depends on the V2O5 concentration in the catalyst.3.The relative amount of the isomeric xylenes and ethylbenzene in the reaction products is apparently due to the isomerization of the isobutylene dimer, which is formed in the first step of the aromatization reaction.

1.An increase in the temperature of the aromatization of propylene and isobutylene in the presence of aluminum oxide from 300 to 625°C is accompanied by an increase in the conversion of the original olefins; appreciable formation of aromatic hydrocarbons occurs only above 500°C. The greatest selectivity with respect to aromatic hydrocarbons is achieved at 550–625°C.2.An increase in contact time is accompanied by a significant increase in the conversion of the original olefins, but does not exhibit an appreciable influence on the composition of the liquid reaction products nor on the selectivity with respect to aromatization.

The primary structure of bovine retinal calcium binding protein P26 has been determined by parallel analysis of protein and corresponding cDNA, This protein is identical to recovering and shares 59% homology with visinin, a cone specific calcium binding protein from chicken retina. Preliminary data are presented on expression of P26 as a fusion protein in E. coli.

The features of the catalytic action of pentasil type zeolites in transformations of low-molecular-weight olefins and paraffins are reviewed. Principal results describing the physicochemical properties of pentasils elucidated by IR spectroscopy, electron microscopy, XPS, and ESR are discussed. The mechanism of the formation of catalytically active sites on the surface of pentasils and the location of modifying elements in the zeolite frameworks are examined. The role of Lewis and Bronsted acid sites in promoting single pathways in the transformations of lower hydrocarbons is specified.

The catalytic and acid properties of erionites with a different degree of decationization were studied. IR spectroscopy showed that Brönsted acid sites are formed on the outer surface of the erionites as a result of decationization. It was shown that these sites are responsible for the occurrence of reactions of oligomerization of isobutylene and structural isomerization of trimethylpentenes.

1.With a constant concentration of Zn (1.5%), the catalytic activity of pentasils in aromatization of C3-C4 alkanes increases as the concentration of Al in the framework increases.2.The selectivity with respect to the formation of aromatic hydrocarbons from propane and isobutane on Zn-containing pentasils is not a function of the Si/Al ratio. Transformation of propane and isobutane into products of aromatization and C1-C2 alkanes takes place parallelly.3.Strong Lewis acid sites responsible for activation of the molecules of lower alkanes are formed as a result of modification of the pentasils with zinc.

1.In studying the isomerization and disproportionation of xylenes, the temperature range of the formation and destruction of active centers in zeolites of the pentasil and mordenite type was established. Active centers resistant to heat treatment at 973–1073 K are present on the surface of zeolites prepared by direct synthesis.2.After treatment of zeolite of the pentasil type with air at 1073–1273 K, the selectivity with respect to formation of p-xylene increased significantly, and the reaction of disproportionation of the xylenes with a decrease in the total catalytic activity was inhibited.

The primary structure of rhodopsin from the octopus Paroctopus defleinihas been determined by parallel analysis of the protein and corresponding cDNA. The amino acid sequence is most similar to the recently cloned Drosophilaopsins. Similarities to bovine and human opsins are also evident. The transmembrane topology of octopus rhodopsin is discussed.

Not Available

Abstract: The results of studies aimed at the development of highly efficient catalysts based on zeolites of the pentasil family for synthesis of aliphatic and aromatic hydrocarbons from C2−C5 olefins and paraffins are summarized.

Conclusion Plutonium breeding in fast reactors themselves will not have any significant effect in the next 20–25 years on growth rate of the capacity of nuclear power stations with fast reactors.