| 1. |
- Aad, G, et al.
(author)
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- 2015
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swepub:Mat__t
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| 2. |
- Reifarth, R., et al.
(author)
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Nuclear astrophysics with radioactive ions at FAIR
- 2016
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 665:1
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Conference paper (peer-reviewed)abstract
- The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process beta-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes.
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| 3. |
- Abdellaoui, G., et al.
(author)
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Meteor studies in the framework of the JEM-EUSO program
- 2017
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In: Planetary and Space Science. - : Elsevier. - 0032-0633 .- 1873-5088. ; 143, s. 245-255
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Journal article (peer-reviewed)abstract
- We summarize the state of the art of a program of UV observations from space of meteor phenomena, a secondary objective of the JEM-EUSO international collaboration. Our preliminary analysis indicates that JEM-EUSO, taking advantage of its large FOV and good sensitivity, should be able to detect meteors down to absolute magnitude close to 7. This means that JEM-EUSO should be able to record a statistically significant flux of meteors, including both sporadic ones, and events produced by different meteor streams. Being unaffected by adverse weather conditions, JEM-EUSO can also be a very important facility for the detection of bright meteors and fireballs, as these events can be detected even in conditions of very high sky background. In the case of bright events, moreover, exhibiting some persistence of the meteor train, preliminary simulations show that it should be possible to exploit the motion of the ISS itself and derive at least a rough 3D reconstruction of the meteor trajectory. Moreover, the observing strategy developed to detect meteors may also be applied to the detection of nuclearites, exotic particles whose existence has been suggested by some theoretical investigations. Nuclearites are expected to move at higher velocities than meteoroids, and to exhibit a wider range of possible trajectories, including particles moving upward after crossing the Earth. Some pilot studies, including the approved Mini-EUSO mission, a precursor of JEM-EUSO, are currently operational or in preparation. We are doing simulations to assess the performance of Mini-EUSO for meteor studies, while a few meteor events have been already detected using the ground-based facility EUSO-TA.
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| 4. |
- Walker, Anthony P, et al.
(author)
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Horizon 2020 EuPRAXIA design study
- 2017
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 874:1
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Journal article (peer-reviewed)abstract
- The Horizon 2020 Project EuPRAXIA ("European Plasma Research Accelerator with eXcellence In Applications") is preparing a conceptual design report of a highly compact and cost-effective European facility with multi-GeV electron beams using plasma as the acceleration medium. The accelerator facility will be based on a laser and/or a beam driven plasma acceleration approach and will be used for photon science, high-energy physics (HEP) detector tests, and other applications such as compact X-ray sources for medical imaging or material processing. EuPRAXIA started in November 2015 and will deliver the design report in October 2019. EuPRAXIA aims to be included on the ESFRI roadmap in 2020.
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| 5. |
- Dub, S. N., et al.
(author)
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Theoretical shear strength and the onset of plasticity in nanodeformation of cubic boron nitride
- 2017
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In: Journal of Superhard Materials. - 1063-4576. ; 39:2, s. 88-98
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Journal article (peer-reviewed)abstract
- The nanoindentation in the continuous stiffness measurement mode was used to investigate the onset of plasticity at the nanodeformation of cubic boron nitride (cBN). This technique allows us to reveal an elastic-plastic transition in the contact and to measure the yield strength of cBN at the nanoscale. An abrupt elastoplastic transition (a pop-in) was observed in the (111) cBN single crystal as a result of a homogeneous or heterogeneous nucleation of dislocations in the previously dislocations-free region under the contact. The analysis of the data obtained at the homogeneous nucleation of dislocations in the contact region made it possible to experimentally estimate the theoretical shear strength of cBN and its ideal (elastic) hardness. In a sample of the fine-grained cBN with a nanotwinned substructure a smooth elastoplastic transition was observed in consequence of the propagation and multiplication of already existing dislocations in the contact region.
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| 6. |
- Kislinskiǐ, Yu V., et al.
(author)
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Structure and electron transport of strontium iridate epitaxial films
- 2015
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In: Physics of the Solid State. - : Pleiades Publishing Ltd. - 1063-7834 .- 1090-6460. ; 57:12, s. 2519-2523
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Journal article (peer-reviewed)abstract
- The crystallographic and electrophysical properties of epitaxial SrIrO3 films, in which the crystal lattice is deformed due to the mismatch between the lattice parameters of strontium iridate and the substrate, have been studied. Substrates (001) SrTiO3, (001) LaAlO3 + Sr2AlTaO6 (LSAT), (110) NdGaO3, and (001) LaAlO3 have been used. As a result of the deformation of the crystal lattice, the electrical resistivities of the films deposited on substrates with different lattice parameters differ by several times. The SrIrO3 films with thickness d = 90 nm, grown on SrTiO3 and LSAT substrates, have a nonmonotonic temperature dependence of the conductivity: type of the temperature dependence of the conductivity changes from metallic to dielectric at T (L) = 200-250 K. The electrical resistance of the films with thicknesses less than 20 nm on all the substrates decreases exponentially with increasing temperature.
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| 7. |
- Solovieva, N., et al.
(author)
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The Holocene environmental history of a small coastal lake on the north-eastern Kamchatka Peninsula
- 2015
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In: Global and Planetary Change. - : Elsevier BV. - 1872-6364 .- 0921-8181. ; 134, s. 55-66
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Journal article (peer-reviewed)abstract
- A radiocarbon and tephra-dated sediment core from Lifebuoy Lake, located on the north-east coast of Kamchatka Peninsula, was analysed for pollen, spores, diatoms, chironomids and tephra in order to uncover regional environmental history. The 6500-year environmental history of Lifebuoy Lake correlates with the broad regional patterns of vegetation development and climate dynamics with both diatoms and chironomids showing near-synchronous changes. Between ca. 6300 and 3900 cal yr BP, the lake ecosystem was naturally enriched, with several Stephanodiscus species dominating the diatom plankton. This natural eutrophication state is likely to be due to a combination of the base-rich catchment geology, the fertilisation effect of several fires in the catchment, silica input from tephra layers and, possibly, nitrogen input from seabirds. The substantial tephra deposit at about 3850 cal yr BP might have stopped sedimentary phosphorus from entering the lake water thus decreasing the trophic state of the lake and facilitating the shift in diatom composition to a benthic Fragiliariaceae complex. Both diatoms and chironomids showed simultaneous compositional changes, which are also reflected by statistically significant changes in their rates of change 300-400 years after the arrival of Pinus pumila in the lake catchment. The rapid increase in both total diatom concentration and the percentage abundance of the large heavy species, Aulacoseira subarctica might be a response to the change in timing and intensity of lake spring turnover due to the changes in the patterns of North Pacific atmospheric circulation, most notably westward shift Of the Aleutian Low. The two highest peaks in A. subarctica abundance at Lifebouy Lake occurred during opposite summer temperature inferences: the earlier peak (3500-2900 cal yr BP) coincided with warm summers and the latter peak (300 cal yr BP-present) occurred during the cold summer period. These imply that A. subarctica shows no direct response to the changes of summer air temperature. Instead, it appears to thrive during the periods of increased winter precipitation, thicker ice and late spring turn-over periods, i.e., shows indirect response to climate. The clearest effect of tephra deposition on the lake ecosystem is above 908 cm (ca. 3800 cal yr BP) where the tephra deposit might have caused the shift from Stephanodiscus-dominated planktonic assemblages to the Fragilariaceae complex of benthic species. Tephra deposits might have also contributed towards the development of eutrophic plankton from about 6300 cal yr BP. It is not certain if several tephra deposits influenced diatom and chironomid changes during the last 300 years. (C) 2015 The Authors. Published by Elsevier B.V.
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| 8. |
- Andrén, Elinor, et al.
(author)
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The relative influences of climate and volcanic activity on Holocene lake development inferred from a mountain lake in central Kamchatka
- 2015
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In: Global and Planetary Change. - : Elsevier BV. - 1872-6364 .- 0921-8181. ; 134, s. 67-81
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Journal article (peer-reviewed)abstract
- A sediment sequence was taken from a closed, high altitude lake (informal name Olive-backed Lake) in the central mountain range of Kamchatka, in the Russian Far East. The sequence was dated by radiocarbon and tephrochronology and used for multi-proxy analyses (chironomids, pollen, diatoms). Although the evolution of Beringian climate through the Holocene is primarily driven by global forcing mechanisms, regional controls, such as volcanic activity or vegetation dynamics, lead to a spatial heterogeneous response. This study aims to reconstruct past changes in the aquatic and terrestrial ecosystems and to separate the climate-driven response from a response to regional or localised environmental change. Radiocarbon dates from plant macrophytes gave a basal date of 7800 cal yr BP. Coring terminated in a tephra layer, so sedimentation at the lake started prior to this date, possibly in the early Holocene following local glacier retreat. Initially the catchment vegetation was dominated by Betula and Alnus woodland with a mosaic of open, wet, aquatic and semi-aquatic habitats. Between 7800 and 6000 cal yr BP the diatom-inferred lake water was pH 4.4-53 and chironomid and diatom assemblages in the lake were initially dominated by a small number of acidophilic/acid tolerant taxa. The frequency of Pinus pumila (Siberian dwarf pine) pollen increased from 5000 cal yr BP and threshold analysis indicates that P. pumila arrived in the catchment between 4200 and 3000 cal yr BP. Its range expansion was probably mediated by strengthening of the Aleutian Low pressure system and increased winter snowfall. The diatominferred pH reconstructions show that after an initial period of low pH, pH gradually increased from 5500 cal yr BP to pH 5.8 at 1500 cal yr BP. This trend of increasing pH through the Holocene is unusual in lake records, but the initially low pH may have resulted directly or indirectly from intense regional volcanic activity during the midHolocene. The chironomid-inferred July temperature reconstruction suggests cool periods between 32002800 cal yr BP and 1100-700 cal yr BP and a warmer period between 2800 and 1100 cal yr BP. Chironomid and diatom DCA scores decline from ca. 6000 cal yr BP, indicating compositional changes in these aquatic assemblages. In comparison declines in pollen PCA scores are delayed, starting ca. 5100 cal yr BP. The results suggest that while catchment vegetation was responding primarily to climate change, the biota within the lake and lake water chemistry were responding to localised environmental conditions. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.
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| 9. |
- Petrov, V., et al.
(author)
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V2X Connectivity : From LTE to Joint Millimeter Wave Vehicular Communications and Radar Sensing
- 2019
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In: Proceedings 53rd Asilomar Conference on Signals, Systems and Computers 2019. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1120-1124
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Conference paper (peer-reviewed)abstract
- To meet the prospective demands of intelligent transportation systems (ITS), the Release 14 (Rel-14) and Rel-15 of the Long Term Evolution (LTE) specifications include solutions for enhanced vehicle-to-everything (V2X) communications. While the technical enablers of Rel-14 are suitable for delivering basic safety messages, Rel-15 supports more demanding ITS services with stringent latency and reliability. Starting in Rel-15 and continuing in Rel-16, the 3GPP was developing a novel radio interface for 5G systems, termed the New Radio (NR), which will enable ultra reliable and low latency communications suitable even for the most demanding ITS applications. In this paper, we overview the new V2X-specific features in Rel-15 and Rel-16. Further, we argue that future V2X and automotive radar systems may reuse common equipment, such as millimeter-wave antenna arrays. We finally discuss the vision of joint vehicular communications and radar sensing as well as characterize unified channel access for millimeter-wave vehicular communications and radar sensing.
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| 10. |
- Wennrich, Volker, et al.
(author)
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Impact processes, permafrost dynamics, and climate and environmental variability in the terrestrial Arctic as inferred from the unique 3.6 Myr record of Lake El'gygytgyn, Far East Russia - A review
- 2016
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In: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 147, s. 221-244
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Journal article (peer-reviewed)abstract
- Lake El'gygytgyn in Far East Russia is a 3.6 Myr old impact crater lake. Located in an area that has never been affected by Cenozoic glaciations nor desiccation, the unique sediment record of the lake represents the longest continuous sediment archive of the terrestrial Arctic. The surrounding crater is the only impact structure on Earth developed in mostly acid volcanic rocks. Recent studies on the impactite, permafrost, and sediment sequences recovered within the framework of the ICDP "El'gygytgyn Drilling Project" and multiple pre-site surveys yielded new insight into the bedrock origin and cratering processes as well as permafrost dynamics and the climate and environmental history of the terrestrial Arctic back to the mid-Pliocene. Results from the impact rock section recovered during the deep drilling clearly confirm the impact genesis of the El'gygytgyn crater, but indicate an only very reduced fallback impactite sequence without larger coherent melt bodies. Isotope and element data of impact melt samples indicate a F-type asteroid of mixed composition or an ordinary chondrite as the likely impactor. The impact event caused a long-lasting hydrothermal activity in the crater that is assumed to have persisted for c. 300 kyr. Geochemical and microbial analyses of the permafrost core indicate a subaquatic formation of the lower part during lake-level highstand, but a subaerial genesis of the upper part after a lake-level drop after the Allerod. The isotope signal and ion compositions of ground ice is overprinted by several thaw freeze cycles due to variations in the talik underneath the lake. Modeling results suggest a modern permafrost thickness in the crater of c. 340 m, and further confirm a pervasive character of the talik below Lake El'gygytgyn. The lake sediment sequences shed new leight into the Pliocene and Pleistocene climate and environmental evolution of the Arctic. During the mid-Pliocene, significantly warmer and wetter climatic conditions in western Beringia than today enabled dense boreal forests to grow around Lake Ergygytgyn and, in combination with a higher nutrient flux into the lake, promoted primary production. The exceptional warmth during the mid-Pliocene is in accordance with other marine and terrestrial records from the Arctic and indicates a period of enhanced "Arctic amplification". The favourable conditions during the mid-Pliocene were repeatedly interrupted by climate deteriorations, e.g., during Marine Isotope Stage (MIS) M2, when pollen data and sediment proxies indicate a major cooling and the onset of local permafrost around the lake. A gradual vegetation change after c. 3.0 Ma points to the onset of a long-term cooling trend during the Late Pliocene that culminated in major temperature drops, first during MIS G6, and later during MIS 104. These cold events coincide with the onset of an intensified Northern Hemisphere (NH) glaciation and the largest extent of the Cordilleran Ice Sheet, respectively. After the Pliocene/Pleistocene transition, local vegetation and primary production in Lake El'gygtygyn experienced a major change from relatively uniform conditions to a high-amplitude glacial-to-interglacial cyclicity that fluctuated on a dominant 41 kyr obliquity band, but changed to a 100 kyr eccentricity dominance during the Middle Pleistocene transition (MPT) at c. 1.2-0.6 Ma. Periods of exceptional warming in the Pleistocene record of Lake El'gygytgyn with dense boreal forests around and peaks of primary production in the lake are assigned to so-called "super-interglacial" periods. The occurrence of these super-interglacials well corresponds to collapses of the West Antarctic Ice Sheet (WAIS) recorded in ice-free periods in the ANDRILL core, which suggests strong intrahemispheric teleconnections presumably driven by changes in the thermocline ocean circulation.
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