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  • 1
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    Observing Earth’s magnetic environment with the GRACE-FO mission (2021)
    Stolle, C. ; Michaelis, I. ; Xiong, C. ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission carries magnetometers that are dedicated to enhance the satellite’s navigation. After appropriate calibration and characterisation of artificial magnetic disturbances, these observations are valuable assets to characterise the natural variability of Earth’s magnetic field. We describe the data pre-processing, the calibration, and characterisation strategy against a high-precision magnetic field model applied to the GRACE-FO magnetic data. During times of geomagnetic quiet conditions, the mean residual to the magnetic model is around 1 nT with standard deviations below 10 nT. The mean difference to data of ESA’s Swarm mission, which is dedicated to monitor the Earth’s magnetic field, is mainly within ± 10 nT during conjunctions. The performance of GRACE-FO magnetic data is further discussed on selected scientific examples. During a magnetic storm event in August 2018, GRACE-FO reveals the local time dependence of the magnetospheric ring current signature, which is in good agreement with results from a network of ground magnetic observations. Also, derived field-aligned currents (FACs) are applied to monitor auroral FACs that compare well in amplitude and statistical behaviour for local time, hemisphere, and solar wind conditions to approved earlier findings from other missions including Swarm. On a case event, it is demonstrated that the dual-satellite constellation of GRACE-FO is most suitable to derive the persistence of auroral FACs with scale lengths of 180 km or longer. Due to a relatively larger noise level compared to dedicated magnetic missions, GRACE-FO is especially suitable for high-amplitude event studies. However, GRACE-FO is also sensitive to ionospheric signatures even below the noise level within statistical approaches. The combination with data of dedicated magnetic field missions and other missions carrying non-dedicated magnetometers greatly enhances related scientific perspectives.
    Description: European Space Agency (FR)
    Description: HEIBRIDS
    Description: Projekt DEAL
    Description: ftp://isdcftp.gfz-potsdam.de/grace-fo/MAGNETIC_FIELD
    Keywords: ddc:538.7 ; Earth’s magnetic field ; Geomagnetism ; Ionospheric currents ; Magnetospheric ring current ; Satellite-based magnetometers ; Platform magnetometers ; GRACE-FO
    Language: English
    Type: doc-type:article
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    CITATION GEO-LEO
  • 2
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    The Mag.num core field model as a parent for IGRF-13, and the recent evolution of the South Atlantic Anomaly (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-11-15
    Description: We present the GFZ candidate field models for the 13th Generation International Geomagnetic Reference Field (IGRF-13). These candidates were derived from the Mag.num.IGRF13 geomagnetic core field model, which is constrained by Swarm satellite and ground observatory data from November 2013 to August 2019. Data were selected from magnetically quiet periods, and the model parameters have been obtained using an iteratively reweighted inversion scheme approximating a robust modified Huber norm as a measure of misfit. The root mean square misfit of the Mag.num.IGRF13 model to Swarm and observatory data is in the order of 3–5 nT for mid and low latitudes, with a maximum of 44 nT for the satellite east component data at high latitudes. The time-varying core field is described by order 6 splines and spherical harmonic coefficients up to degree and order 20. We note that the temporal variation of the core field component of the Mag.num.IGRF13 model is strongly damped and shows a smooth secular variation that suits well for the IGRF, where secular variation is represented as constant over 5-year intervals. Further, the external field is parameterised by a slowly varying part and a more rapidly varying part controlled by magnetic activity and interplanetary magnetic field proxies. Additionally, the Euler angles of the magnetic field sensor orientation are co-estimated. A widely discussed feature of the geomagnetic field is the South Atlantic Anomaly, a zone of weak and decreasing field strength stretching from southern Africa over to South America. The IGRF and Mag.num.IGRF13 indicate that the anomaly has developed a second, less pronounced eastern minimum at Earth’s surface since 2007. We observe that while the strong western minimum continues to drift westwards, the less pronounced eastern minimum currently drifts eastward at Earth’s surface. This does not seem to be linked to any eastward motion at the core–mantle boundary, but rather to intensity changes of westward drifting flux patches contributing to the observed surface field. Also, we report a sudden change in the secular variation measured at two South Atlantic observatories around 2015.0, which occurred shortly after the well-known jerk of 2014.0.
    Description: European Space Agency
    Description: Projekt DEAL
    Description: https://earth.esa.int/web/guest/swarm/data-access.
    Description: https://www.gfz-potsdam.de/magmodels/
    Keywords: ddc:538.7 ; Geomagnetic field model ; Main magnetic field ; South Atlantic Anomaly ; Swarm ; IGRF
    Language: English
    Type: doc-type:article
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    CITATION GEO-LEO
  • 3
    Electronic Resource
    Electronic Resource
    Superposed epoch analysis applied to large-amplitude travelling convection vortices (1998)
    Springer
    Annales geophysicae 16 (1998), S. 743-753 
    Details
    ISSN: 0992-7689
    Keywords: Ionosphere (Aural ionosphere; Ionospheremagnetosphere interactions) ; Magnetospheric Physics (current system)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract For the six months from 1 October 1993 to 1 April 1994 the recordings of the IMAGE magnetometer network have been surveyed in a search for largeamplitude travelling convection vortices (TCVs). The restriction to large amplitudes (〉100 nT) was chosen to ensure a proper detection of evens also during times of high activity. Readings of all stations of the northern half of the IMAGE network were employed to check the consistency of the ground signature with the notation of a dual-vortex structure moving in an azimuthal direction. Applying these stringent selection criteria we detected a total of 19 clear TCV events. The statistical properties of our selection resemble the expected characteristics of large-amplitude TCVs. New and unexpected results emerged from the superposed epoch analysis. TCVs tend to form during quiet intervals embedded in moderately active periods. The occurrence of events is not randomly distributed but rather shows a clustering around a few days. These clusters recur once or twice every 27 days. Within a storm cycle they show up five to seven days after the commencement. With regard to solar wind conditions, we see the events occurring in the middle of the IMF sector structure. Large-amplitude TCVs seem to require certain conditions to make solar wind transients ‘geoeffective’, which have the tendency to recur with the solar rotation period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-998-0743-0
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  • 4
    Electronic Resource
    Electronic Resource
    HWA 285 (Propentofylline)—A New Compound for the Treatment of Both Vascular Dementia and Dementia of the Alzheimer Type (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 777 (1996), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Notes: The pharmacological profile of HWA 285 favors its use in patients with both Alzheimer's disease (PDD) and/or vascular dementia (MID). Clinical trials showed clinically relevant, statistically significant efficacy in the domains of cognitive function, global function and activities of daily living (ADL) in both PDD and MID. HWA 285 had a prolonged symptomatic effect for at least 12 months, although therapeutic effects were seen already after the first 3 months of treatment. HWA 285 was very well tolerated for at least 1 year.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1996.tb34453.x
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  • 5
    Electronic Resource
    Electronic Resource
    Miniband transport in vertical superlattice field-effect transistors (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1564-1566 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study the nonequilibrium transport of two-dimensional electrons through a periodic potential. Our samples are fabricated using the cleaved-edge overgrowth technique to provide a vertical field-effect transistor with an undoped GaAs/AlGaAs superlattice channel orthogonal to the current flow. We find a pronounced negative differential resistance, the magnitude of which increases with increasing modulation strength. The data are qualitatively consistent with the Esaki–Tsu transport model in minibands, which we calculate for the given samples. We emphasize the significance of the two-dimensionality of the electron system and the gate to inhibit domain formation. Weak features in the source-drain current are attributed to Bloch-phonon resonances. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1390320
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  • 6
    Electronic Resource
    Electronic Resource
    Realization of AlGaAs antidot arrays by pulsed laser interference gratings (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 1497-1499 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: AlGaAs antidot arrays with about 107 antidots are produced by single-shot interference processing with a pulsed high-power Nd:YAG laser system. We apply magnetotransport experiments and atomic force microscopy (AFM) to explore the electronic and geometric properties of the arrays. The size of the antidot arrays are 3 mm×3 mm and the period varies from 400 to 1000 nm. The dots are elliptic or circular and have diameters ranging from 255 to 690 nm. The magnetotransport experiments are performed at 1.5 K in van der Pauw contact configuration. The laser structuring leaves the two dimensional electron density nearly unchanged but decreases the mobility by a factor of about 30. Several maxima are detected in the low magnetic field magnetoresistivity which are discussed based on the geometric data determined by AFM. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365933
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  • 7
    Electronic Resource
    Electronic Resource
    Heterologous expression of archaeal selenoprotein genes directed by the SECIS element located in the 3′ non-translated region (2001)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 40 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Previous in silico analysis of selenoprotein genes in Archaea revealed that the selenocysteine insertion (SECIS) motif necessary to recode UGA with selenocysteine was not adjacent to the UGA codon as is found in Bacteria. Rather, paralogous stem–loop structures are located in the 3′ untranslated region (3′ UTR), reminiscent of the situation in Eukarya. To assess the function of such putative SECIS elements, the Methanococcus jannaschii MJ0029 (fruA, which encodes the A subunit of the coenzyme F420-reducing hydrogenase) mRNA was mapped in vivo and probed enzymatically in vitro. It was shown that the SECIS element is indeed transcribed as part of the respective mRNA and that its secondary structure corresponds to that predicted by RNA folding programs. Its ability to direct selenocysteine insertion in vivo was demonstrated by the heterologous expression of MJ0029 in Methanococcus maripaludis, resulting in the synthesis of an additional selenoprotein, as analysed by 75Se labelling. The selective advantage of moving the SECIS element in the untranslated region may confer the ability to insert more than one selenocysteine into a single polypeptide. Evidence for this assumption was provided by the finding that the M. maripaludis genome contains an open reading frame with two in frame TGA codons, followed by a stem–loop structure in the 3′ UTR of the mRNA that corresponds to the archaeal SECIS element.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02433.x
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  • 8
    Electronic Resource
    Electronic Resource
    The influence of antiserum on the metastasis of ascites cells from the Yoshida Sarcoma (1966)
    Springer
    Cellular and molecular life sciences 22 (1966), S. 300-301 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Intravenöse Injektion von Ascites-Zellen des Yoshida-Sarkoms in Ratten bewirkte, dass 27 Tage nach der Applikation 16 von 17 Tieren gestorben sind. Dasselbe Ergebnis wurde erhalten bei Injektion von normalem Serum oder bei der Kombination dieses Serums mit 6-Mercaptopurin. Dagegen führte gleichzeitige Applikation von Antiserum und 6-Mercaptopurin zu der erstaunlichen Tatsache, dass nach 40 Tagen etwa 60% der so behandelten Tiere keinen Tumor aufwiesen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01900461
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  • 9
    Electronic Resource
    Electronic Resource
    An interlaboratory test for certification of potassium chloride as a certified reference material (CRM) for solution calorimetry (1988)
    Springer
    Journal of thermal analysis and calorimetry 33 (1988), S. 359-363 
    Details
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Lösungsenthalpie von KCl in Wasser (Molverhältnis 1∶2000) bei 298.15 K wurde in einem Vergleichstest in mehreren Laboratorien der DDR gemessen. Das Testmaterial wurde in den Laboratorien des ASMW hergestellt. Eine coulometrische Präzisionstitration des Chlorids ergab seine Reinheit zu (0.9999±0.0001 g/g. Der übereinstimmende Wert für die Lösungsenthalpie wurde in dem Test zu ΔH s 298.15 =(17.47±0.07) kJ mol−1 gefunden, in guter Übereinstimmung mit experimentellen Angabe aus internationalen Laboratorien. Nach Abschluss des Testes ist das Material als bestätigter Bezugsstandard verwendbar.
    Abstract: РЕЗЮМЕ В ГДР было проведено и змерение энтальпии растворения хлорнда калия в 2000 моль/ моль Н2О при температ уре 298.75 К. С этой целью был и проведены междунаро дные лабораторные испытания. Испытывае мый материал был полу чен в лабораториях ASMW. Чистот а материала, определенная высоко точным кулонометрич еским титрованием хлорид-и она, составляла 0.9999±0.0001 г·г−1. Значение энтал ьпии растворения, полученное таким тес товым методом, состав ляла ΔH S298.15=17.47±0.01 кдж·моль−1, что хорошо согласуется с экспериментальными значениями, найденными в других м еждународных научны х лабораториях. После о кончания испытания, в ещество было применено как CRM.
    Notes: Abstract The enthalpy of solution of KCl in H2O (1∶2000 mol·mol−1) at 298.15 K was measured in an interlaboratory test in the G.D.R. The test material was prepared in the ASMW laboratories. The purity found on the high-precision coulometric titration of chloride was 0.9999±0.0001 g·g−1. The consensus value of the enthalpy of solution in the test was ΔH s 298.15 =17.47±0.07 kJ·mol−1. This result is in good agreement with experimental values from recognized international scientific laboratories. The test material is applicable as a CRM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01914624
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  • 10
    Electronic Resource
    Electronic Resource
    New spectral detection and elimination test algorithms of ECG and EOG artefacts in neonatal EEG recordings (1987)
    Springer
    Medical & biological engineering & computing 25 (1987), S. 127-130 
    Details
    ISSN: 1741-0444
    Keywords: Artefact detection ; ECG interference ; EOG interference ; Neonatal EEG ; Spectral parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract New methods for the detection of ECG and EOG artefacts in the EEG are introduced, which can also be used for the evaluation of the quality of the elimination procedure. These algorithms are based on the estimation of the power or coherence spectrum by means of FFT. The advantage of this method is that the EEG spectrum is monitored by the test algorithm. The spectrum will be plotted if no influence of the ECG and EOG can be found. On the other hand, if artefacts are detected the correction of the EEG time series will be carried out and the spectrum of the corrected EEG time series will be plotted after repeated monitoring by the test algorithm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02442839
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