ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    Simultaneous observations of magnetospheric ELF/VLF emissions in Canada, Finland, and Antarctica (2017)
    Wiley
    Details
    Publication Date: 2017-06-16
    Description: To investigate longitudinal extent of electromagnetic wave activity, we report the first simultaneous ground-based observations of magnetospheric ELF/VLF emissions at the following three longitudinally-separated stations at auroral and subauroral latitudes: Athabasca, Canada (ATH; magnetic latitude: 61.3 ∘ N); Kannuslehto, Finland (KAN; 64.4 ∘ N); and Syowa Station, Antarctica (SYO; 70.5 ∘ S). The magnetic local time (MLT) separations of SYO-KAN, ATH-SYO, and ATH-KAN, are 3, 8, and 11 h, respectively. Simultaneous observation data at these stations are available for a total of 48 days in 2012-2014. The simultaneous occurrence rates of ELF/VLF emissions are 9.8 % , 2.5 % , and 3.6 % for SYO-KAN, ATH-SYO, and ATH-KAN, respectively. We found that the simultaneous wave occurrence rate between two stations is higher in the morning-dayside sector, indicating that the longitudinal extent of the emissions exhibits MLT dependence. When emissions are simultaneously observed at two stations, the average AE and |Dst| indices tend to be higher. Similarly, if the two stations are more separated in MLT, the average |Dst| index increases. These results suggest that the longitudinal extent of ELF/VLF emissions increases with increasing geomagnetic activity.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    A geomagnetic paleointensity record of 0.6 to 3.2 m.y. from sediments in the western equatorial Pacific and remanent magnetization lock-in depth (2017)
    Wiley
    Details
    Publication Date: 2017-09-27
    Description: Information of past geomagnetic intensity variations is important for better understanding of the geodynamo, and efforts to recover continuous paleointensity records continue, in particular for ages older than 2 Ma. In this study, a new relative paleointensity (RPI) record of 0.6 to 3.2 Ma was obtained from a sediment core in the western equatorial Pacific, which has good age control by the oxygen-isotope stratigraphy from 2.0 to 3.2 Ma. The RPI record could well be correlated to existing RPI templates despite the low sedimentation rate of ~5 m/m.y., and will be useful for future construction of a stacked paleointensity curve beyond 2 Ma. Magnetic minerals of the core consist mainly of biogenic and terrigenous oxidized magnetite. Some rock-magnetic contamination to long-term RPI changes is recognized; RPI inversely correlates with the ratio of anhysteretic remanent magnetization to saturation remanent magnetization, which may be caused by differences in remanence acquisition efficiency between the biogenic and terrigenous magnetic components. The lock-in depth of the studied core is estimated to be approximately zero from a line of evidence including no apparent offset between PRI and cosmogenic beryllium nuclide flux changes across some polarity boundaries. Lock-in depths vary locally from core to core or even within a single core, and have no obvious relation with sedimentation rates and carbonate contents. Lock-in depths may be controlled by factors that are currently difficult to be evaluated, such as variations in sediment flocculation sizes and biogeochemical remanent magnetization dependent to chemical conditions of sediments.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    Possible cause of extremely bright aurora witnessed in East Asia on 17 September 1770 (2017)
    Wiley
    Details
    Publication Date: 2017-10-11
    Description: Extremely bright aurora was witnessed in East Asia on 17 September 1770, according to historical documents. The aurora was described as “as bright as a night with full moon” at magnetic latitude of 25°. The aurora was dominated by red color extending from near the horizon up beyond the polar star (corresponding to elevation angle of ~35°). We performed a two-stream electron transport code to calculate the volume emission rates at 557.7 nm [OI] and 630.0 nm [OI]. Two types of distribution of precipitating electrons were assumed. The first one is based on the unusually intense electron flux measured by the DMSP satellite in the March 1989 storm. The distribution consists of hot (peaking at 3 keV) and cold (peaking at 71 eV) components. The second one is the same as the first one, but the hot component is removed. We call this high-intensity low energy electrons (HILEEs). The first spectrum results in an auroral display with a bright, lower green border. The second one results in red-dominated aurora extending up to the elevation angle of 35° when the equatorward boundary of the electron precipitation is located at 32° invariant latitude. The poleward boundary of the precipitation would be 42° invariant latitude, or greater to explain the auroral display extending from near the horizon. The origin of the HILEEs is probably the plasma sheet, or the plasmasphere that is transported earthward to L ~1.39 due to enhanced magnetospheric convection. Local heating, or acceleration is also plausible.
    Print ISSN: 1539-4964
    Electronic ISSN: 1542-7390
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    facet.materialart.
    Unknown
    Robust bias correction model for estimation of global trend in marine populations (2017)
    Wiley
    In: Ecosphere
    Details
    Publication Date: 2017-12-22
    Description: In modeling biological and ecological processes from data, it is essential to deal with data selection bias properly in order to obtain reliable and reasonable predictions. To incorporate the mechanism of selection bias into a statistical analysis, a propensity score (PS) is widely employed as an inverse probability weight in order to obtain a consistent estimation of a binary response variable of interest. However, the estimation performance often becomes unstable due to the mis-estimation of the PS. In order to obtain a consistent estimation as well as to stabilize the estimation performance, we propose a new regression model that incorporates the PS as an explanatory variable. Moreover, we show that the proposed model has a the property of double robustness, which enables us to obtain a consistent estimation of the response without suffering from selection bias if either the PS model or the proposed model is correctly specified. The robust bias correction model also accommodates heterogeneity of data distributions based on an asymmetric logistic model, which in turn improves model fitting and prediction accuracy. The PS in our regression model enables us to estimate consistently the global fish stock status even if the information of the stock status available is biased.
    Electronic ISSN: 2150-8925
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Wiley on behalf of The Ecological Society of America (ESA).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 5
    facet.materialart.
    Unknown
    Pre-state of stress and fault behavior during the 2016 Kumamoto earthquake (M7.3) (2017)
    Wiley
    Details
    Publication Date: 2017-12-30
    Description: Fault behavior during an earthquake is controlled by the state of stress on the fault. Complex co-seismic fault slip on large earthquake faults has recently been observed by dense seismic networks, which complicates strong motion evaluations for potential faults. Here, we show the three-dimensional pre-stress field related to the 2016 Kumamoto earthquake. The estimated stress field reveals a spatially variable state of stress that forced the fault to slip in a direction predicted by the “Wallace and Bott Hypothesis”. The stress field also exposes the pre-condition of pore fluid pressure on the fault. Large co-seismic slip occurred in the low-pressure part of the fault. However, areas with highly pressured fluid also showed large displacement, indicating that the seismic moment of the earthquake was magnified by fluid pressure. These pre-rupture data could contribute to improved seismic hazard evaluations.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 6
    facet.materialart.
    Unknown
    Effects of intensification of the Indian Summer Monsoon on northern Andaman Sea sediments during the past 700 years (2017)
    Wiley
    Details
    Publication Date: 2017-05-13
    Description: ABSTRACT Recent studies have revealed an intensification of the Indian Summer Monsoon (ISM) over the past 700 years, but its influence on the sediments in the northern Andaman Sea is unclear. To examine this influence, we used radiocarbon-dated sediment core StMY6, acquired 100 km offshore in the northern Andaman Sea from the Ayeyarwady River mouth, and obtained a 700-year-long record of the grain-size distribution and geochemistry of the sedimentary sequence. The ISM influences precipitation surrounding the Ayeyarwady River, and thus the river water and sediment discharges to the northern Andaman Sea near the river mouth in the Ayeyarwady River and the weathering intensity in the river catchment. Based on the system, we propose that higher sedimentation rates and larger modal grain size (the most abundant size in the grain-size distribution of sediments) and lower carbonate concentrations after about AD 1600 can be attributed to higher ISM intensity. Profiles of total organic carbon (TOC) content and carbon/nitrogen (C/N) ratios, however, did not show any trends after about AD 1600, which suggests that the ISM has had little influence on these proxies at this site.
    Print ISSN: 0267-8179
    Electronic ISSN: 1099-1417
    Topics: Geography , Geosciences
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 7
    facet.materialart.
    Unknown
    First evidence of patchy flickering aurora modulated by multi-ion electromagnetic ion cyclotron waves (2017)
    Wiley
    Details
    Publication Date: 2017-04-27
    Description: Electromagnetic ion cyclotron (EMIC) waves, one of the possible origins of flickering aurora, have been thought to modulate the electron flux at a few thousand kilometers. In fact, flickering aurora with a frequency range of 3–15 Hz has often been identified by ground-based optical observations and has been interpreted to be caused by O + -band EMIC waves. However, extant research to date has not identified possible signatures of H + -band EMIC waves due to technical limitations of ground-based high-speed imagers. The present study shows the first evidence that patchy flickering aurora could be modulated by H + -band EMIC waves, based on the data obtained from imaging observations at 160 frames per second. The sporadic appearance of the flickering aurora in the frequency range of 50–80 Hz coexisted with typical flickering auroras of approximately 10 Hz. These results are consistent with the hypothesis that flickering auroras are generated by multi-ion EMIC waves.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 8
    facet.materialart.
    Unknown
    Three-dimensional resistivity structure in Ishikari Lowland, Hokkaido, northeastern Japan - Implications to strain concentration mechanism (2017)
    Wiley
    Details
    Publication Date: 2017-02-11
    Description: The Ishikari Lowland on the island of Hokkaido in northeastern Japan is situated at the end of a westward-moving foreland fold-and-thrust belt from the Hidaka collision zone, where the northeastern Japan and Kurile arcs meet. This activity forms a tectonic zone under an east–west compression field in this region. A magnetotelluric resistivity survey was performed to investigate the mechanism for the strain concentration in this region. A three-dimensional (3D) resistivity inversion showed a conductive thick sedimentary layer and an underlying resistive basement. Remarkable conductors were found in the resistive basement beneath the Ishikari-teichi-toen fault zone (ITFZ) and the Shikotsu caldera. The conductors beneath the ITFZ were interpreted as aqueous fluids that accumulated in the damaged zone in connection with the formation of pull-apart faults and horst. In contrast, the conductor beneath the Shikotsu caldera corresponds to a magmatic fluid path from the upper mantle. These features suggest that the ductile deformation in the upper crust contribute to the strain concentration in this region. The soft thick sediments allow ductile deformations to occur. Furthermore, local fluid-rich zones in the basement cause the crustal strength to be heterogeneous. These thick sediments and local fluids in the basement both contribute to the strain concentration in this region. This article is protected by copyright. All rights reserved.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 9
    facet.materialart.
    Unknown
    Pore pressure migration during hydraulic stimulation due to permeability enhancement by low-pressure subcritical fracture slip (2017)
    Wiley
    Details
    Publication Date: 2017-04-01
    Description: Understanding the details of pressure migration during hydraulic stimulation is important for the design of an energy extraction system and reservoir management, as well as for the mitigation of hazardous induced seismicity. Based on microseismic and regional stress information, we estimated the pore pressure increase required to generate shear slip on an existing fracture during stimulation. Spatiotemporal analysis of pore pressure migration revealed that lower pore pressure migrates further and faster, and that higher pore pressure migrates more slowly. These phenomena can be explained by the relationship between fracture permeability and stress state criticality. Subcritical fractures experience shear slip following smaller increases of pore pressure and promote migration of pore pressure because of their enhanced permeability. The difference in migration rates between lower and higher pore pressures suggests that the optimum wellhead pressure is the one that can stimulate relatively permeable fractures, selectively. Its selection optimizes economic benefits and minimizes seismic risk.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Rapid low-temperature synthesis of tetragonal single-phase Li7La3Zr2O12 (2017)
    Wiley
    Details
    Publication Date: 2017-01-11
    Description: The formation of Li 7 La 3 Zr 2 O 12 (LLZ), a Li ion conducting oxide with a garnet-type crystal structure, from a powder mixture of Li 2 CO 3 , La(OH) 3 , and ZrO 2 was investigated, and two possible reaction pathways were identified. Based on the obtained results, LLZ was synthesized at low temperatures and short reaction times, using Li 2 CO 3 , La(OH) 3 , and La 2 Zr 2 O 7 (instead of ZrO 2 ) as starting materials. According to the proposed method, single-phase LLZ was obtained by heating the initial mixture to 800°C for 1 hour in air, which eliminated possible Li losses. The produced LLZ species exhibited a tetragonal crystal structure with the lattice parameters a= 1.3189(3) nm and c= 1.2694(1) nm, while their transmission electron microscopy images confirmed that LLZ formation occurred through the dissolution of La 2 Zr 2 O 7 and La(OH) 3 in a Li 2 CO 3 melt followed by LLZ precipitation from solution.
    Print ISSN: 0002-7820
    Electronic ISSN: 1551-2916
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Wiley
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...