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The paper presents experimental studies of parametric X-ray radiation produced by the interaction of relativistic electrons with powder targets and textured polycrystals. The difference in the obtained X-ray spectra is shown. The experimental data obtained are compared with values calculated according to the PXR kinematic theory. [ABSTRACT FROM AUTHOR] more...

Previous analytical and simulation‐based analyses suggest that deeper land surface models are needed to realistically simulate the terrestrial thermal state in climate models, with implications for land‐atmosphere interactions. Analytical approaches mainly focused on the subsurface propagation of harmonics such as the annual temperature signal, and a direct comparison with climate‐change model output has been elusive. This study addresses the propagation of a harmonic pulse fitted to represent the timescale and amplitude of anthropogenic warming. Its comparison to land model simulations with stepwise increased bottom boundary depth leads to an agreement between the simulation‐based and analytical frameworks for long‐term climate trends. Any depth increase gradually decreases the relative error in the subsurface thermodynamics, and a minimum depth of 170 m is recommended to simulate the ground climate adequately. The approach provides an accurate estimate of the required land‐model depth for climate‐change simulations and assesses the relative bias in insufficiently deep land models. Plain Language Summary: Many current‐generation climate models have land components that are too shallow. Under climate change conditions, the long‐term warming trend at the surface propagates deeper into the ground than the commonly used 3–10 m. Shallow models alter the terrestrial heat storage and distribution of temperatures in the subsurface, influencing the simulated land‐atmosphere interactions. Previous studies focusing on annual timescales suggest that deeper models are required to match subsurface‐temperature observations and the classic analytical heat conduction solution. However, for a systematic investigation of land‐model deepening in the frame of anthropogenic climate change, the classic analytical solution is inaccurate because it does not mimic the timescale and amplitude of the simulated warming trend. This study intends to bridge the gap between analytical and simulation‐based estimates of the subsurface thermodynamic state by adapting the classic analytical framework to mimic long‐term anthropogenic warming. The analysis shows that a land‐model depth of at least 170 m is recommended for a proper simulation of the post‐1850 ground climate, which differs up to 30% from the estimate of the classic approach. Compared to previous studies, this provides an accurate estimate of the required land model depth for long‐term climate‐change simulations and indicates the relative bias in insufficiently deep land models. Key Points: Heat conduction from analytical and numerical estimates suggests a required land‐model depth of 170 m for climate change simulationsAgreement between numerical and analytical estimates on climate change timescales gives more confidence for the required land‐model depthStepwise land‐model depth increase gradually reduces the relative error of shallow models in climate‐change simulations [ABSTRACT FROM AUTHOR] more...

The paper presents data obtained on the production rates of cosmogenic radionuclides of different half-life in 42 chondrites that fell in 1959–2016. A quantitative approach is developed for using cosmogenic radionuclides as natural detectors of galactic cosmic rays (GCR) for different time periods and for different heliocentric distances. A long set of homogeneous data is compiled on 54Mn, 22Na, and 26Al production rates along meteorite orbits (at 2–4 AU) in 1959–2016. Its correlative analysis with the corresponding sets of data on some major parameters of magneto hydrodynamic processes in the heliosphere allows us to identify principal relationships and trends in the temporal and spatial variations in GCR (E > 100 MeV) in the inner heliosphere (≤5 AU) over a long time scale. The monitoring of this analysis makes it possible both to study these processes in the past and to predict their characteristics in the future, which still cannot be done by means of direct measurements of the GCR intensity in interplanetary space. A project is suggested to demonstrate the expedience of establishing an international meteorite-patrol survey to study spatiotemporal variations in GCR in the inner heliosphere by means of measuring and analyzing the production rates of cosmogenic radionuclides in chondrites falling to Earth. No alternative projects have been put forth as of yet. [ABSTRACT FROM AUTHOR] more...

Cosmogenic radionuclides with half-life periods T1/2 ranging from several days to a million years, produced in the nuclear reactions of galactic cosmic rays (GCR) with meteoritic matter, provide valuable information on the GCR intensity variations on a long time scale (∼1 million years) within meteorite orbits 2–4 AU from the Sun. Information on the variations of GCR gradients in the inner heliosphere was obtained by comparing the measured contents of 54Mn and 22Na in stone meteorites (chondrites) with known orbits at the time of their fall to Earth with the calculated production rates of these radionuclides in them using balloon intensity measurements of GCR (E > 100 MeV) in the stratosphere at appropriate times. Although individual gradient values show significant uncertainties, the important information is that cosmogenic radionuclides in chondrites predict low gradients (0–10% per 1 AU) for all periods of minimum solar activity in 1957–2013, according to direct measurements in interplanetary space. High gradients (50–100% per 1 AU) are predicted for periods of maximum solar activity, especially in 1992 and 2012 (up to ∼200% per 1 AU). Average values of gradients are (20 ± 10)% per 1 AU for modern solar cycles (according to the production rate of 22Na), similar to the average values for the last ∼1 million years (according to the production rate of 26Al), which indicates the constancy of the solar modulation of the GCR, at least for the last million years. [ABSTRACT FROM AUTHOR] more...

The results of multiyear investigations of cosmogenic radionuclide production rates along the orbits of 42 chondrites that fell to the Earth between 1959 and 2016 are presented. They constitute a long set of homogeneous data, statistical smoothing of which demonstrates some main regularities of the distribution and variation of the galactic cosmic rays (GCR) with energy >100 MeV in the internal (<5 AU) heliosphere. This set is exclusive, and it has timeless importance for all the future investigations of the magneto-hydrodynamic peculiarities of the GCR solar modulation mechanism. Analysis of the 26Al contents in ten chondrites of known orbits allowed us to find the spatial profile of the GCR intensity (E > 100 MeV), averaged over a 1 My in the internal heliosphere, testifying to continual development and dissipation of a layer of the solar wind magnetic irregularities, which efficiently modulates cosmic radiation. It suggests constancy of the magneto-hydrodynamic environment in the Solar System for at least the last million years. [ABSTRACT FROM AUTHOR] more...

Based on the analysis of published data on exposure ages of iron meteorites determined with the K/K method ( T ) and ages calculated using short-lived cosmogenic radionuclides (with the half-life T < 1 Myr) in combination with stable cosmogenic isotopes of noble gases (T), the following results have been obtained. (1) The distribution of T ages (106 values) has an exponential shape, similar to that for ordinary chondrites, but different from the distribution of T ages (80 values). The difference is most likely due to small amounts of data for meteorites with low T ages (less than ~200-300 Myr). The latter can be ascribed to the difficulty of measurement of small concentrations of cosmogenic potassium isotopes. This circumstance makes the selection of meteorites with K/K ages nonrepresentative and casts doubt on the correctness of conclusions about the variations of the intensity of galactic cosmic rays (GCR) based on the analysis of distribution of these ages. (2) The magnitude of the known effect (systematic overestimation of T ages in comparison with T ages) has been refined. The value k = T / T = 1.51 ± 0.03 is acquired for the whole population of data. We have shown the inefficiency of the explanation of this effect on account of an exponential change in the GCR intensity ( I ) with time ( T) according to the relation I = I exp(-γ T) over the whole range of ages of iron meteorites. (3) In order to explain the overestimation of T ages in comparison with T ages, a model has been proposed, according to which the GCR intensity has exponentially increased in the interval of 0-1500 Myr governed by the relation: I = I (1 + αexp(-βT)). For one of the variants of this model, the GCR intensity has exponentially increased by a factor of two only over the recent ~300 Myr, remaining approximately constant for the rest of the time. The data acquired with the use of this model indicate that the measured T ages are close to the actual time that the meteorites existed in space; the data are in agreement with the observed exponential distribution of T ages. [ABSTRACT FROM AUTHOR] more...

This work was performed within the OLYMPIA experiment on the study of tracks of heavy and superheavy cosmic ray nuclei in olivine crystals from Marjalahti and Eagle Station pallasites. Depth distributions of the track formation rate for heavy cosmic ray nuclei in olivine crystals from pallasites of different pre-atmospheric sizes were obtained. The dependences obtained were used to analyze the data on the track density in olivine crystals from the Marjalahti pallasite. In three crystals, the track distribution with a high density gradient was detected, which indicates a complicated radiation history of the meteorite. [ABSTRACT FROM AUTHOR] more...

We discuss the possibility of detecting deep convection in the Lofoten Basin of the Norwegian Sea based on the eddy structures revealed from the satellite data. Satellite altimetry, SAR imagery, and MODIS satellite spectral radiometer sea-surface temperature (SST) data are used in the analysis, along with the data of oceanographic Argo floats. It is shown that the eddies identified from the satellite data correspond to the convective cells in the same region according to the data of the Argo floats. We consider several examples of the summer eddy and one winter eddy and the corresponding structures in the ocean measured by the Argo floats when they were located close to the identified eddies. As this method develops and improves, it can be used for the analysis of the dynamic of oceanic eddies in the region of the Lofoten Basin, and possibly in other regions with active deep convection. [ABSTRACT FROM AUTHOR] more...

To ascertain probable variations of the intensity of galactic cosmic rays (GCR) for the recent billion years, the distribution of exposure ages T of iron meteorites has been analyzed. We considered all ~80 values of ages from the data by Voshage and Feldmann (1979), Voshage et al. (1983), and Voshage (1984), as well as a set of values obtained from the correction for eliminating the meteorites formed in a single collision. To correct the data, the Akaike information criterion was used. For the distributions of the phase values Ph = T/t-int( T/t), the dependence of the criterion χ on the presumable period t in the exposure age variations was analyzed. For t ~ 400-500 Myr and, partly, for t ~ 150 Myr, the significant deviations of this criterion from the corresponding mean values were found. To clear up the influence of the GCR intensity variations on the age distribution, the numerical models were calculated with an account of the set of ages randomly distributed in the interval of 0-1000 Myr with the presumptive mean lifetime of iron meteorites in outer space τ = 700 Myr. It has been ascertained that, for variations with a period of t = 450 Myr, the distribution of exposure ages of the model set is similar to that found for iron meteorites. The obtained data suggest that the GCR intensity variations with a period of approximately 400-500 Myr have probably existed during the recent billion years. These variations may be caused by periodic passages of the Solar System through spiral arms of the Galaxy. It has been shown that the earlier discussed changes in the GCR intensity with a period of ~150 Myr (Shaviv, 2002; 2003; Scherer et al., 2006) are less defined. [ABSTRACT FROM AUTHOR] more...

We propose an algorithm for the generalization of cartographic objects that can be used to represent maps on different scales. [ABSTRACT FROM AUTHOR]

Copyright of Stratum Plus Journal is the property of P.P. Stratum plus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Copyright of Stratum Plus Journal is the property of P.P. Stratum plus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Thermoluminescence, noble gases, and the tracks of iron-group elements and cosmogenic radionuclides of various half-lives were examined in the fresh-fallen Ash Creek (L6) and Tamdakht (H5) chondrites. The experimental information thus obtained and theoretical simulations were used to study the shock-thermal and exposure histories of the chondrites, to evaluate their preatmospheric sizes and masses, values of ablation, the sizes of their orbits, and to monitor the distribution and variations in cosmic radiation in the heliosphere during the transitional period of minimum between solar cycles 23 and 24. [ABSTRACT FROM AUTHOR] more...

Meteorite data on monitoring the variations in GCR gradients at 2-4 AU from the Sun over the period 1957-2010 demonstrate the effect of the inversion of solar magnetic fields (SMFs) during the solar maximum periods of 11-year solar cycles on the depth of GCR modulation in the heliosphere. [ABSTRACT FROM AUTHOR] more...

Thermoluminescence, tracks of VH nuclei, and cosmogenic radionuclides with various half-lives were studied of the recently fallen Bukhara CV3 and Kilabo LL6 chondrites. The obtained experimental information and theoretical modeling were utilized to examine the thermal impact and exposure histories of these chondrites, estimate the sizes and masses they had before entering the atmosphere, extent of their ablation, the circumferences of the orbits, and to evaluate the distribution and variations in cosmic radiation in the heliosphere in the maximum phase of the 23rd solar cycle. The Kilabo LL6 chondrite and the Bensour LL6 (which fall six months earlier) were determined to be genetically related to the asteroid 3628 Boznemcova. [ABSTRACT FROM AUTHOR] more...

Synthetic oligodeoxynucleotides (ODNs) had been employed in gene modification and represent an alternative approach to ‘cure’ genetic disorders caused by mutations. To test the ability of ODN-mediated gene repair in bone marrow-derived mesenchymal stem cells (MSCs), we established MSCs cell lines with stably integrated mutant neomycin resistance and enhanced green fluorescent protein reporter genes. The established cultures showed morphologically homogenous population with phenotypic and functional features of mesenchymal progenitors. Transfection with gene-specific ODNs successfully repaired targeted cells resulting in the expression of functional proteins at relatively high frequency approaching 0.2%. Direct DNA sequencing confirmed that phenotype change resulted from the designated nucleotide correction at the target site. The position of the mismatch-forming nucleotide was shown to be important structural feature for ODN repair activity. The genetically corrected MSCs were healthy and maintained an undifferentiated state. Furthermore, the genetically modified MSCs were able to engraft into many tissues of unconditioned transgenic mice making them an attractive therapeutic tool in a wide range of clinical applications.Gene Therapy (2008) 15, 1035–1048; doi:10.1038/gt.2008.31; published online 13 March 2008 [ABSTRACT FROM AUTHOR] more...

The article discusses the origin of some chondrites. According to the article, successive collisions which came from intermediate bodies of several sizes where the objects surpass for 10 kilometers (km) in diameter are regarded as the last parent bodies of chondrites. Base on observations, some chondrites and asteroids have the same spectral types specifically the reflection spectrum of LL6 Manbhoom chondrite which is the same to the reflection spectrum of the mainbelt 3628 Boznemcova asteroid. more...

Cosmogenic radionuclides with distinctive half-lives from chondritic falls were used as natural detectors of galactic cosmic rays (GCR). A unique series of uniform data was obtained for variations in the integral gradients of GCR with a rigidity of R > 0.5 GV in 1955–2000 on heliocentric distances of 1.5–3.3 AU and heliographic latitudes between 23° S and 16° N. Correlation analysis was performed for the variations in GCR gradients and variations in solar activity (number of sunspots, SS, and intensity of the green coronal line, GCL), the intensity of the interplanetary magnetic field (IMF), and the inclination of the heliospheric current sheet (HCS). Distribution and variations of GCR were analyzed in 11-year solar cycles and during a change in 22-year magnetic cycles. The detected dependencies of GCR gradients on the intensity of IMF and HCS inclination provided insight into the differences in the processes of structural transformation of IMF during changes between various phases of solar and magnetic cycles. The investigated relationships lead to the conclusion that a change of secular solar cycles occurred during solar cycle 20; moreover, there is probably still an increase in the 600-year solar cycle, which can be among the major reasons for the observed global warming. [ABSTRACT FROM AUTHOR] more...

Transient transfection has been widely used in many biological applications including gene regulation and DNA repair, but, so far, little attention has been paid to cellular responses induced by the transfected DNA. Here, we report that double-stranded (ds) DNA introduced into mammalian cells induced expression of a variety of genes involved in DNA damage signaling and DNA repair. The expression profile of the induced genes was highly dependent on the cell type, suggesting interactions between exogenous dsDNA and cellular proteins. Moreover, each cell line elicited a markedly different level of intrinsic cellular responses to the introduced dsDNA. Furthermore, the presence of single-stranded oligonucleotides or short duplexes consisting of two complementary oligonucleotides did not affect cellular response, indicating that the induction was highly dependent on the structure and length of exogenous DNA. The extent of induction of DNA damage, signaling and DNA repair activities correlated to episomal and chromosomal gene correction frequencies. In addition, the presented data indicate that the presence of exogenous dsDNA triggered a DNA damage response by activation of ATR (ataxia telangiectasia-Rad3-related) but not ATM (ataxia telangiectasia mutated) pathway.Gene Therapy (2006) 13, 266–275. doi:10.1038/sj.gt.3302643; published online 22 September 2005 [ABSTRACT FROM AUTHOR] more...

Examines the distribution and variation of galactic cosmic rays in the heliosphere. Investigation of heliosphere; Manifestation of the solar cycle; Modulation of the galactic cosmic rays.

The sensitivity of an idealized climate system model consisting of an atmospheric GCM coupled to an oceanic upper mixed layer on an aquaplanet is analyzed. There is no seasonal cycle and the solar radiation is taken to be symmetric about the equator. The system is integrated with the observed CO2 (330 ppm) until it reaches a quasi-equilibrium climate. To study the sensitivity we double the CO2 and again integrate until the system reaches a new equilibrium climate. To simplify the linear analysis we assume that the atmosphere is always in quasi-equilibrium (typical atmospheric adjustment times being much shorter than that of the oceanic upper mixed layer). We introduce a linear surface energy budget sensitivity (or response) operator consisting of a Jacobian matrix of the surface budget with respect to the surface temperature. The operator is used to construct a linear estimate of the surface temperature change that results from the CO2 doubling. It is found that the temperature response obtained from the linear extimate compares well with the results of the full 3D run. The shape of the response looks very similar to that of the least stable mode of the linear surface budget sensitivity operator. The importance of different components of the initial forcing at the surface is discussed. The role of the individual components in determining the final equilibrium climate is also studied. [ABSTRACT FROM AUTHOR] more...

We have shown that various forms of oligonucleotides, chimeric RNA-DNA oligonucleotide (RDO) and singlestranded oligodeoxynucleotide (ODN), are capable of chromosomal gene alterations in mammalian cells. Using two ODNs we corrected an inactivating mutation in the tyrosinase gene and introduced an activating mutation into the c-kit gene in a single albino mouse melanocyte. Relying on a pigmentation change caused by tyrosinase gene correction, we determined the frequency of gene targeting events ranging from 2 × 10[sup -4] to 1 × 10[sup -3], which is comparable to our previously published data using RDO. However, ODN showed more reproducible gene correction than RDO and produced pigmented cells among 60% of experiments, in comparison with 10% by RDO. DNA sequence analysis of the converted cells revealed that two out of eight individual pigmented clones harbored the mutated c-kit gene. Targeted modification of both genes resulted in the ability of the tyrosinase to convert tyrosine to melanin, and in the constitutive activation of the Kit receptor kinase. Thus, for the first time, we demonstrate the feasibility of simultaneous targeting of two genes in a single cell and show that a selection strategy to identify cells that have undergone a gene modification can enrich the targeted cells with the desired gene alteration. [ABSTRACT FROM AUTHOR] more...

We demonstrate that relatively short single-stranded oligodeoxynucleotides, 25-61 bases homologous to the target sequence except for a single mismatch to the targeted base, are capable of correcting a single point mutation (G to A) in the mutant β-galactosidase gene, in nuclear extracts, episome, and chromosome of mammalian cells, with correction rates of approximately 0.05%, 1% and 0.1%, respectively. Surprisingly, these short single-stranded oligonucleotides (ODN) showed a similar gene correction frequency to chimeric RNA-DNA oligonucleotide, measured using the same system. The in vitro gene correction induced by ODN in nuclear extracts was not dependent on the length or polarity of the oligonucleotide. In contrast, the episomal and chromosomal gene corrections were highly dependent on the ODN length and polarity. ODN with a homology of 45 nucleotides showed the highest frequency and ODN with antisense orientation showed a 1000-fold higher frequency than sense orientation, indicating a possible influence of transcription on gene correction. Deoxyoligonucleotides showed a higher frequency of gene correction than ribo-oligonucleotides of the identical sequence. These results show that a relatively short ODN can make a sequence-specific change in the target sequence in mammalian cells, at a similar frequency as the chimeric RNA-DNA oligonucleotide. [ABSTRACT FROM AUTHOR] more...

The distribution of the cosmic-ray exposure ages (T) of iron meteorites was analyzed to establish the possible variations in the intensity of the galactic cosmic ray (GCR) over the last billion years. The analysis was made for the entire data set containing ~80 age values from the literature (Voshage et al., 1983) and the corrected set after the exclusions of paired meteorites (using the Akaike information criterion). The dependence of the criterion χ in the distribution of the phase values Ph = T/t-int(T/t) on the values of the assumed period (t) of GCR variations was analyzed for both sets of meteorites. The significant deviations of these parameters from the respective average values were found for t ~ 400-500 Myr and, in part, for t ~ 150 Myr. These deviations were interpreted by numerical modeling using the values of ages randomly distributed in the range of 0-1000 Ma. It was found that for variations with a period of 450 Myr, the distribution of the phase values and cosmic-ray exposure ages in the model data set is similar to that of iron meteorites. These results testify to the existence of the GCR variations with a period of ~400-500 Myr during the last 1 Gyr. The variations in the GCR flux can be explained by periodic galactic spiral arm crossings of the solar system. The GCR variations with a period of ~150 Myr discussed in the previous studies (Shaviv, 2002; 2003; Scherer et al., 2006) appears to be less certain. [ABSTRACT FROM AUTHOR] more...

Based on the example of the measured and calculated contents of cosmogenic radionuclides in freshly fallen Chelyabinsk and Kosice chondrites, an indirect approach to studying variations in galactic cosmic rays is presented that uses variations in the rates of production of radionuclides with different half-lives in the meteorites that continuously fall to Earth from orbits of different sizes and inclinations. The advantages of monitoring these data over a long time scale to establish the main regularities of solar modulation processes in the heliosphere are demonstrated. The possible effect of stochastic factors in the operation of the solar dynamo had on the peculiarities of GCR modulation in solar cycles 23 and 24 is discussed. [ABSTRACT FROM AUTHOR] more...

During the 1974–1987 period 12 paceful nuclear explosions were conducted in the Republic of Sakha (Yakutia). For the first time239,240Pu and238Pu concentrations were determined in samples of soils, bottom sediments and lichen taken at the “Craton-3” and “Crystal” nuclear explosion sites. At the “Craton-3”239,240Pu concentrations in the range 6.2 mBq/g to 5.9 Bq/g samples of soil and239,240Pu concentrations up to 7.4 Bq/g in samples of lichen were observed.239,240Pu concentration measurements in bottom sediments of a stream washing out the banking around the borehole of “Craton-3” show that plutonium migrates in the direction of the Markha river. At the “Crystal” site local plutonium concentrations up to 35 Bq/g in soil and 1.8 Bq/g in lichen were observed. [ABSTRACT FROM AUTHOR] more...

DNA vaccines are attractive candidates for tumor immunotherapy. However, the potential of DNA vaccines in treating established malignant lesions has yet to be demonstrated. Here we demonstrate that transient alteration of either intratumoral or intradermal (ID) chemotactic gradients provide a favorable milieu for DNA vaccine-mediated activation of tumor-specific immune response in both prophylactic and therapeutic settings. Specifically, we show that priming of established B16 ID melanoma lesions via forced intratumoral expression of CCL21 boosted DNA vaccination-dependent systemic cytotoxic immune response leading to the regression of tumor nodules. In this setting, application of CCL20 was not effective likely due to the engagement of the regulatory T cells. However, priming of the skin at DNA vaccine administration sites outside the tumor bed with both CCL20 and CCL21 chemokines along with structural modifications of the DNA vaccine significantly improved vaccine efficacy. This optimized ID vaccination regimen led to the inhibition of distant established melanomas and prolonged tumor-free survival of mice observed in 60% of vaccinated animals with complete tumor remission in 30%. These effects were mediated by extranodal priming and activation of T cells at vaccine administration sites and progressive accumulation of systemic antigen-specific cytotoxic T cells (CTLs) on successive vaccinations. These results underscore the potential of chemokine-enhanced DNA vaccination to mount therapeutic immune response against established tumors. [ABSTRACT FROM AUTHOR] more...

This paper presents the results of the mineralogical, petrographic, elemental, and isotopic analysis of the Chelyabinsk meteorite and their geochemical interpretation. It was shown that the meteorite can be assigned to LL5-group ordinary chondrites and underwent moderate shock metamorphism (stage S4). The Chelyabinsk meteorite contains a significant fraction (approximately one-third by volume) of shock-melted material similar in composition to the main volume of the meteorite. The results of isotopic analysis suggest that the history of meteorite formation included an impact event approximately 290 Ma ago. [ABSTRACT FROM AUTHOR] more...

The bottom of Lake Chebarkul' was investigated by ground penetrating radar at the fall site of a large fragment of the Chelyabinsk meteorite. Linear profiles and 3D reconstructions revealed an anomalous depression of the lake floor relief and the disturbance of the structure of the ice cover, which indicate the possible place of meteorite fragment occurrence. [ABSTRACT FROM AUTHOR] more...

The article focuses on a study which analyzed the character of the solar magnetic field restructuring, as well as its effect on the modulation depth of galactic cosmic rays (GCR) in the heliosphere. It notes on the correlations between the GCR gradients and solar activity (SA). It illustrates the secular SA cycles from 1700-2001. more...

Based on the analysis of data in [1, 2] on the concentrations of noble gases and the cosmic ray exposure age (CREA) of chromite grains in fossil meteorites, it was demonstrated in [3] that the distributions of gas concentrations and cosmic ray exposure ages can be explained under the assumption of the fall of a single meteorite in the form of a meteorite shower in southern Sweden less than 0.2 Ma after the catastrophic destruction of the parental body (asteroid) of L chondrites in space at approximately 470 Ma. This assumption differs from the conclusion in [1, 2, 4] about the long-lasting (for 1-2 Ma) delivery of L chondrites to the Earth, with the intensity of the flux of this material one to two orders of magnitude greater than now. The analysis of newly obtained data on samples from the Brunflo fossil meteorite [5] corroborates the hypothesis of a meteorite shower produced by the fall of a single meteorite. The possible reason for the detected correlations between the cosmic ray exposure ages of meteorites and the masses of the samples with the Ne concentrations can be the occurrence of Ne of anomalous isotopic composition in the meteorites. [ABSTRACT FROM AUTHOR] more...

The article focuses on an analytical simulation method in order to calculate rate of mass transfer of the impurities along the cold traps in case of fast reactors. It focuses on the system of equations for a multicomponent medium including the equations of hydrodynamics, transfer of thermal energy and physicochemical kinetics of impurities. It also presents mathematical equations for calculating the parameters that increase the operating efficiency of a cold trap. more...

The sources of impurities entering the sodium in fast reactors were investigated. The analysis showed that oxygen and hydrogen can be removed from the sodium by using cold traps in all operating regimes of a nuclear power plant as well as hot traps. An operating regime preventing hydrogen accumulation in the first-loop cold trap is proposed for a system purifying the first two loops. A computer code for calculating the impurity mass transfer is perfected. Test calculations showed that the procedure developed and the code are both serviceable. The deviation of the computational results from the experimental data is about 30% on average. For a built-in purification system, it is essential to develop a cold trap with a large impurity capacity. It is shown on the basis of experiments that such cold traps can in principle be developed. Thermohydraulic and mass-transfer codes must be developed in order to realize this possibility. [ABSTRACT FROM AUTHOR] more...

Copyright of Stratum Plus Journal is the property of P.P. Stratum plus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

From the analysis of the data acquired for the chromite grains recovered from fossil meteorites from Sweden (Heck et al., 2004, 2008), the dependence of the exposure age of meteorites on a mass of the examined samples was obtained (Alexeev, 2010). This dependence, whatever its nature, puts into question the validity of the conclusion on a long lasting (over the course of 1-2 Myr) and substantial (by 1-2 orders of magnitude) increase in the intensity of the flux of meteorites (L-chondrites) that fell onto the Earth about 470 Myr ago. All of the fossil meteorites found in southern Sweden could be the fragments of a single meteorite that fell as a meteorite shower in the Thorsberg quarry region ∼470 Myr ago. [ABSTRACT FROM AUTHOR] more...

We present the results of the analysis of the data obtained by Heck et al. (2004; 2008) regarding the contents of He and Ne and the exposure age of chromite grains recovered from fossil meteorites (L-chondrites) found in marine limestone—mid-Ordovician sediments—in the Thorsberg and Gullhogen quarries of southern Sweden. It has been shown that the increase of the content of noble gases in the chromite grains (by 1–2 orders of magnitude) and their exposure age with a decreasing mass of the samples (by approximately an order of magnitude) can be caused by an increase of the portion of small grains and by their poor preservation in the samples of small mass. The revealed relationships, as well as the fact that practically all fossil meteorites were found in a small area (∼6000 m), can be explained by the following assumption: a meteorite shower, caused by a single meteorite, fell ∼470 Myr; this occurred less than 0.2 Myr after the catastrophic destruction of the L-chondrite parent body. The time of this fall corresponds to that of the formation of the oldest sedimentation stratum, containing the meteorite fragments, in the Thorsberg quarry. Meteorite fragments in the younger strata are most likely the result of the subsequent redeposition that occurred in a shallow sea, when the sediment mass was forming. In this case, to explain the distribution of fossil meteorites in the mid-Ordovician sediments in Sweden, there is no necessity to hypothesize that an intense flux of meteorites was falling onto the Earth over the course of ∼1–2 Myr about 470 million years ago. [ABSTRACT FROM AUTHOR] more...

The metallogenic efficiency of the marginal sea lithosphere of Northeastern Asia is associated mainly with the ore formation variety of the remaining cratons and microcratons that defined the structural peculiarity of the region; these are setoffs of the Precambrian basement, brachyform, anticline highs, and genesis of rifts within TMA periods. These formations allowed us to explain the reasons for the unique metal-bearing feature of the marginal sea lithosphere of the Pacific Ocean ore belt in addition to phenomena of an inherited nature of mineralization and conditions of formation of polychronous ore deposits. [ABSTRACT FROM AUTHOR] more...

Recent observations show dramatic changes of the Arctic atmosphere–ice–ocean system. Here the authors demonstrate, through the analysis of a vast collection of previously unsynthesized observational data, that over the twentieth century the central Arctic Ocean became increasingly saltier with a rate of freshwater loss of 239 ± 270 km3 decade-1. In contrast, long-term (1920–2003) freshwater content (FWC) trends over the Siberian shelf show a general freshening tendency with a rate of 29 ± 50 km3 decade-1. These FWC trends are modulated by strong multidecadal variability with sustained and widespread patterns. Associated with this variability, the FWC record shows two periods in the 1920s–30s and in recent decades when the central Arctic Ocean was saltier, and two periods in the earlier century and in the 1940s–70s when it was fresher. The current analysis of potential causes for the recent central Arctic Ocean salinification suggests that the FWC anomalies generated on Arctic shelves (including anomalies resulting from river discharge inputs) and those caused by net atmospheric precipitation were too small to trigger long-term FWC variations in the central Arctic Ocean; to the contrary, they tend to moderate the observed long-term central-basin FWC changes. Variability of the intermediate Atlantic Water did not have apparent impact on changes of the upper–Arctic Ocean water masses. The authors’ estimates suggest that ice production and sustained draining of freshwater from the Arctic Ocean in response to winds are the key contributors to the salinification of the upper Arctic Ocean over recent decades. Strength of the export of Arctic ice and water controls the supply of Arctic freshwater to subpolar basins while the intensity of the Arctic Ocean FWC anomalies is of less importance. Observational data demonstrate striking coherent long-term variations of the key Arctic climate parameters and strong coupling of long-term changes in the Arctic–North Atlantic climate system. Finally, since the high-latitude freshwater plays a crucial role in establishing and regulating global thermohaline circulation, the long-term variations of the freshwater content discussed here should be considered when assessing climate change and variability. [ABSTRACT FROM AUTHOR] more...

The global warming on Earth during the last century has been discussed in many studies. The most significant factors of climate change are the increase in the atmospheric concentration of greenhouse gases, catastrophic eruptions of volcanoes, and variations in the solar activity. In this paper, we consider the character of climate change and its possible relation to solar-activity variations using the data of the global network of meteorological stations on temperature variations in different regions across the globe from 1880 and information about variations in the relative sunspot number over the last 300 years and temporal variations in the total solar irradiation. We found that the annual mean sunspot number increased on average by about 0.2% per year in both 11-year and secular cycles. The increase in the globally averaged surface air temperature in the period 1880–2004 was Δ t = 0.61 ± 0.04 °C. The difference in Δ t calculated for periods with different solar-activity levels in 11-year cycles was estimated. This difference was most clearly revealed over land at high latitudes of the northern hemisphere. The medians of the distributions of the annual mean surface air temperature over land, ocean, and over the entire globe in years with high solar activity in the secular cycle are significantly greater than the corresponding values related to the years of low solar activity. Noticeable falls in temperature (by ∼0.1–0.2°C) through ∼1900–1920 and 1945–1980 are likely to be associated with the radiation balance perturbation caused by a large number of catastrophic volcanic eruptions during these periods. A considerable warming during the last three decades is most probably due to the substantial growth in the rate of carbon dioxide input to the atmosphere and the corresponding large increase in its concentration. The importance of this factor of global warming becomes even greater if we bear in mind that the solar activity in the secular cycle declines after 1970. [ABSTRACT FROM AUTHOR] more...

Polar amplification of surface warming has previously been displayed by one of the authors in a simplified climate system model with no ice-albedo feedbacks. A physical mechanism responsible for this pattern is presented and tested in an energy balance model and two different GCMs through a series of fixed-SST and “ghost forcing” experiments. In the first ghost forcing experiment, 4 W/m2 is added uniformly to the mixed layer heat budget and in the second and third, the same forcing is confined to the tropics and extra-tropics, respectively. The result of the uniform forcing is a polar amplified response much like that resulting from a doubling of CO2. Due to an observed linearity this response can be interpreted as the sum of the essentially uniform response to the tropical-only forcing and a more localized response to the extra-tropical-only forcing. The flat response to the tropical forcing comes about due to increased meridional heat transports leading to a warming and moistening of the high-latitude atmosphere. This produces a longwave forcing on the high-latitude surface budget which also has been observed by other investigators. Moreover, the tropical surface budget is found to be more sensitive to SST changes than the extra-tropical surface budget. This strengthens the tendency for the above mechanism to produce polar amplification, since the tropics need to warm less to counter an imposed forcing. [ABSTRACT FROM AUTHOR] more...

The results of studying the distributions of stable radiogenic and cosmogenic isotopes of noble gases in ordinary chondrites are reviewed here: the distributions of gas-retention and exposure ages are analyzed, the chronology and consequences of catastrophic destruction of the parent bodies of H and L chondrites are discussed, the fallen and preatmospheric masses of Antarctic and non-Antarctic meteorites are compared, the diffusion losses of noble gases in meteorites are considered, the ablation of meteorites and their mean lifetime after separation from the parent bodies are estimated, and a number of other problems are discussed. [ABSTRACT FROM AUTHOR] more...