Specific interplanetary conditions for CIR-, Sheath-, and ICME-induced geomagnetic storms obtained by double superposed epoch analysis

The comparison of specific interplanetary conditions for 798 magnetic storms with Dst < -50 nT for the period 1976-2000 was made on the basis of the OMNI archive data.We categorized various large-scale types of solar wind as interplanetary drivers of storms: corotating interaction region (CIR), Sheath, interplanetary CME (ICME) including magnetic cloud (MC) and Ejecta, separately MC and Ejecta, and "Indeterminate" type. The data processing was carried out by the method of double superposed epoch analysis which uses two reference times (onset of storm and the minimum Dst index) and make a re-scaling of main phase of storm a such way that after this transformation all storms have equal durations of main phase in new time reference frame. This method reproduced some well-known results and allowed us to obtain some new results. Specifically, obtained results demonstrate high importance of Sheath in generation of magnetic storms as well as a significant differences in properties of MC and Ejecta and in their geoeffectiveness.Comment: 21 pages, 9 figures, 1 table, submitted to J. of Advances in Space Research on 29 July, 2009 for Special Issue "Space Weather Advances

Thermoelectric prospects of nanomaterials with spin-orbit surface bands

Nanostructured composites and nanowire arrays of traditional thermoelectrics like Bi, Bi(1-x)Sb(x) and Bi(2)Te(3) have metallic Rashba surface spin-orbit bands featuring high mobilities rivaling that of the bulk for which topological insulator behavior has been proposed. Nearly pure surface electronic transport has been observed at low temperatures in Bi nanowires with diameter around the critical diameter, 50 nm, for the semimetal-to semiconductor transition. The surface contributes strongly to the thermopower, actually dominating for temperatures T < 100 K in these nanowires. The surface thermopower was found to be -1 T microvolt/(K^2), a value that is consistent with theory. We show that surface electronic transport together with boundary phonon scattering leads to enhanced thermoelectric performance at low temperatures of Bi nanowire arrays. We compare with bulk n-BiSb alloys, optimized CsBi(4)Te(6) and optimized Bi(2)Te(3). Surface dominated electronic transport can be expected in nanomaterials of the other traditional thermoelectrics.Comment: 18 pages, 3 figure

An early Emsian (Zlichovian) ammonoid assemblage from Sangibaland Mountain (Shakhimardan River Basin) (South Tien Shan, Kyrgyzstan)

© 2017, The Author(s). Early Emsian (Zlichovian) ammonoids are recorded from a section of neritic deposits on the western and northwestern slopes of Sangibaland Mountain (right bank of the Shakhimardan River, near the village of Jiydelik, South Fergana, South Tien Shan, Kyrgyzstan) including other faunas such as conodonts, dacryoconarids, brachiopods, trilobites, and corals. The ammonoid fauna includes Erbenoceras cf. solitarium (Barrande, 1865), E. kimi Bogoslovsky, 1980 and new species of teicherticeratids. This combination of taxa allows the host beds to be correlated with the Zlichovian LDIII Zone. Ammonoids come from the Katran Formation, from beds previously recognised as the Sandal Formation, which is well–known for its neritic assemblages, interpreted as inhabitants of shallow shelf zones in the northern regions of the Paleozoic Alai–Tarim Terrane. Near the end of the Zlichovian, when the Dalejan transgression spread to the Sangibaland Region, ammonoids colonised the neritic basin near a carbonate platform, already inhabited by abundant benthic fauna. The co-occurrence of neritic and pelagic organisms is a useful feature providing a basis for the correlation between the pelagic and neritic successions of the lower Emsian (Zlichovian)