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  • Wiley  (17)
  • American Chemical Society  (6)
  • International Union of Crystallography (IUCr)  (5)
  • American Association for the Advancement of Science (AAAS)  (3)
  • 1
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    Validation for Global Solar Wind Prediction Using Ulysses Comparison: Multiple Coronal and Heliospheric Models Installed at the Community Coordinated Modeling Center (2016)
    Wiley
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    Publikationsdatum: 2016-08-02
    Beschreibung: The prediction of the background global solar wind is a necessary part of space weather forecasting. Several coronal and heliospheric models have been installed and/or recently upgraded at the Community Coordinated Modeling Center (CCMC), including the Wang-Sheely-Arge (WSA)-Enlil model, MHD-Around-a-Sphere (MAS)-Enlil model, Space Weather Modeling Framework (SWMF), and heliospheric tomography using interplanetary scintillation (IPS) data. Ulysses recorded the last fast latitudinal scan from southern to northern poles in 2007. By comparing the modeling results with Ulysses observations over seven Carrington rotations, we have extended our third-party validation from the previous near-Earth solar wind to mid-to-high latitudes, in the same late declining phase of solar cycle 23. Besides visual comparison, we have quantitatively assessed the models’ capabilities in reproducing the time series, statistics, and latitudinal variations of solar wind parameters for a specific range of model parameter settings, inputs, and grid configurations available at CCMC. The WSA-Enlil model results vary with three different magnetogram input. The MAS-Enlil model captures the solar wind parameters well, despite its underestimation of the speed at mid-to-high latitudes. The new version of SWMF misses many solar wind variations probably because it uses lower grid resolution than other models. The IPS-Tomography cannot capture the latitudinal variations of solar wind well yet. Because the model performance varies with parameter settings which are optimized for different epochs or flow states, the performance metric study provided here can serve as a template that researchers can use to validate the models for the time periods and conditions of interest to them.
    Print ISSN: 1539-4964
    Digitale ISSN: 1542-7390
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 2
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    Near-Earth Heliospheric Magnetic Field Intensity since 1750. Part 1: Sunspot and Geomagnetic Reconstructions (2016)
    Wiley
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    Publikationsdatum: 2016-06-19
    Beschreibung: We present two separate time series of the near-Earth heliospheric magnetic field strength (B) based on geomagnetic data and sunspot number (SSN). The geomagnetic-based B series from 1845-2013 is a weighted composite of two series that employ the interdiurnal variability index; this series is highly correlated with in situ spacecraft measurements of B (correlation coefficient, r = 0.94; mean square error, MSE = 0.16 nT 2 ). The SSN-based estimate of B, from 1750-2013, is a weighted composite of eight time series derived from two separate reconstruction methods applied to four different SSN time series, allowing determination of the uncertainty from both the underlying sunspot records and the B-reconstruction methods. The SSN-based composite is highly correlated with direct spacecraft measurements of B and with the composite geomagnetic B time series from 1845-2013 (r = 0.91; MSE = 0.24 nT 2 ), demonstrating that B can accurately reconstructed by both geomagnetic and sunspot-based methods. The composite sunspot and geomagnetic B time series, with uncertainties, are provided as supplementary electronic material.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 3
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    Rocket-borne Measurements of Electron Temperature and Density with the Electron Retarding Potential Analyzer (ERPA) instrument (2016)
    Wiley
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    Publikationsdatum: 2016-06-18
    Beschreibung: Determining electron temperature in the ionosphere is a fundamentally important measurement for space science. Obtaining measurements of electron temperatures at high altitudes (〉700 km) is difficult because of limitations on ground-based radar and classic spacecraft instrumentation. In light of these limitations, the rocket-borne Electron Retarding Potential Analyzer (ERPA) was developed to allow for accurate in situ measurement of ionospheric electron temperature with a simple and low-resource instrument. The compact ERPA, a traditional retarding potential analyzer with multiple baffle collimators, allows for a straightforward calculation of electron temperature. Since its first mission in 2004, it has amassed significant flight heritage and obtained data used in multiple studies investigating a myriad of phenomena related to magnetosphere-ionosphere coupling. In addition to highlighting the scientific contributions of the ERPA instrument, this paper outlines its theory and operation, the methodology used to obtain electron temperature measurements, and a comparative study suggesting that the ERPA can also provide electron density measurements.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 4
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    Near-Earth Heliospheric Magnetic Field Intensity Since 1750. Part 2: Cosmogenic Radionuclide Reconstructions (2016)
    Wiley
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    Publikationsdatum: 2016-06-18
    Beschreibung: This is Part 2 of a study of the near-Earth heliospheric magnetic field strength, B, since 1750. Part 1 [ Owens et al ., 2016] produced composite estimates of B from geomagnetic and sunspot data over the period 1750-2013. Sunspot-based reconstructions can be extended back to 1610, but the paleo-cosmic ray (PCR) record is the only data set capable of providing a record of solar activity on millennial timescales. The process for converting 10 Be concentrations measured in ice cores to B is more complex than with geomagnetic and sunspot data and the uncertainties in B derived from cosmogenic nuclides (~20% for any individual year) are much larger. Within this level of uncertainty, we find reasonable overall agreement between PCR-based-B and the geomagnetic- and SSN-based series. This agreement was enhanced by excising low-values in PCR-based B attributed to high-energy solar proton events. Other discordant intervals, with as yet unspecified causes remain included in our analysis. Comparison of three-year averages centred on sunspot minimum yields reasonable agreement between the three estimates, providing a means to investigate the long-term changes in the heliospheric magnetic field into the past even without a means to remove solar proton events from the records.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 5
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    Validation for Solar Wind Prediction at Earth: Comparison of Coronal and Heliospheric Models Installed at the CCMC (2015)
    Wiley
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    Publikationsdatum: 2015-04-17
    Beschreibung: Multiple coronal and heliospheric models have been recently upgraded at the Community Coordinated Modeling Center (CCMC), including the Wang-Sheely-Arge (WSA)-Enlil model, MHD-Around-a-Sphere (MAS)-Enlil model, Space Weather Modeling Framework (SWMF), and heliospheric tomography using interplanetary scintillation data. To investigate the effects of photospheric magnetograms from different sources, different coronal models, and different model versions on the model performance, we run these models in 10 combinations. Choosing 7 Carrington rotations in 2007 as the time window, we compare the modeling results with the OMNI data for near-Earth space environment during the late declining phase of solar cycle 23. Visual comparison is proved to be a necessary addition to the quantitative assessment of the models’ capabilities in reproducing the time series and statistics of solar wind parameters. The MAS-Enlil model captures the time patterns of solar wind parameters better while the WSA-Enlil model matches with the time series of normalized solar wind parameters better. Models generally overestimate slow wind temperature, underestimate fast wind temperature and magnetic field. Using improved algorithms, we have identified magnetic field sector boundaries (SBs) and slow-to-fast stream interaction regions (SIRs) as focused structures. The success rate of capturing them and the time offset vary largely with models. For this quiet period, the new version of MAS-Enlil model works best for SBs, while heliospheric tomography works best for SIRs. The new version of SWMF with more physics added needs more development. General strengths and weaknesses for each model are diagnosed to provide an unbiased reference to model developers and users.
    Print ISSN: 1539-4964
    Digitale ISSN: 1542-7390
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 6
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    Near‐Earth solar wind forecasting using corotation from L5: The error introduced by heliographic latitude offset (2019)
    Wiley
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    Publikationsdatum: 2019
    Beschreibung: Abstract Routine in‐situ solar wind observations from L5, located 60° behind Earth in its orbit, would provide a valuable input to space‐weather forecasting. One way to ulitise such observations is to assume that the solar wind is in perfect steady state over the 4.5 days it takes the Sun to rotate 60° and thus near‐Earth solar wind in 4.5‐days time would be identical to that at L5 today. This corotation approximation is most valid at solar minimum when the solar wind is slowly evolving. Using STEREO data, it has been possible to test L5‐corotation forecasting for a few months at solar minimum, but the various contributions to forecast error cannot be disentangled. This study uses 40+ years of magnetogram‐constrained solar wind simulations to isolate the effect of latitudinal offset between L5 and Earth due to the inclination of the ecliptic plane to the solar rotational equator. Latitudinal offset error is found to be largest at solar minimum, due to the latitudinal ordering of solar wind structure. It is also a strong function of time of year; maximum at the solstices and very low at equinoxes. At solstice, the latitudinal offset alone means L5‐corotation forecasting is expected to be less accurate than numerical solar wind models, even before accounting for time‐dependent solar wind structures. Thus, a combination of L5‐corotation and numerical solar wind modelling may provide the best forecast. These results also highlight that three‐dimensional solar wind structure must be accounted for when performing solar wind data assimilation.
    Print ISSN: 1539-4964
    Digitale ISSN: 1542-7390
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 7
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    A nonpeptidyl mimic of superoxide dismutase with therapeutic activity in rats (1999)
    American Association for the Advancement of Science (AAAS)
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    Publikationsdatum: 1999-10-09
    Beschreibung: Many human diseases are associated with the overproduction of oxygen free radicals that inflict cell damage. A manganese(II) complex with a bis(cyclohexylpyridine)-substituted macrocyclic ligand (M40403) was designed to be a functional mimic of the superoxide dismutase (SOD) enzymes that normally remove these radicals. M40403 had high catalytic SOD activity and was chemically and biologically stable in vivo. Injection of M40403 into rat models of inflammation and ischemia-reperfusion injury protected the animals against tissue damage. Such mimics may result in better clinical therapies for diseases mediated by superoxide radicals.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Salvemini, D -- Wang, Z Q -- Zweier, J L -- Samouilov, A -- Macarthur, H -- Misko, T P -- Currie, M G -- Cuzzocrea, S -- Sikorski, J A -- Riley, D P -- New York, N.Y. -- Science. 1999 Oct 8;286(5438):304-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉MetaPhore Pharmaceuticals, 1910 Innerbelt Business Center Drive, St. Louis, MO 63114, USA. dsalvemini@metaphore.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10514375" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Anti-Inflammatory Agents, Non-Steroidal/chemical ; synthesis/chemistry/metabolism/*therapeutic use ; Cytoprotection ; Dinoprostone/metabolism ; Dose-Response Relationship, Drug ; Drug Design ; Drug Stability ; Inflammation/*drug therapy ; Interleukin-1/metabolism ; L-Lactate Dehydrogenase/metabolism ; Male ; Manganese ; Molecular Mimicry ; Neutrophils/drug effects ; Organometallic Compounds/chemical synthesis/chemistry/metabolism/*toxicity ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury/*drug therapy ; Splanchnic Circulation ; *Superoxide Dismutase/metabolism ; Superoxides/*metabolism ; Time Factors ; Tumor Necrosis Factor-alpha/metabolism
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
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  • 8
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    Probing the solar magnetic field with a Sun-grazing comet (2013)
    American Association for the Advancement of Science (AAAS)
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    Publikationsdatum: 2013-06-08
    Beschreibung: On 15 and 16 December 2011, Sun-grazing comet C/2011 W3 (Lovejoy) passed deep within the solar corona, effectively probing a region that has never been visited by spacecraft. Imaged from multiple perspectives, extreme ultraviolet observations of Lovejoy's tail showed substantial changes in direction, intensity, magnitude, and persistence. To understand this unique signature, we combined a state-of-the-art magnetohydrodynamic model of the solar corona and a model for the motion of emitting cometary tail ions in an embedded plasma. The observed tail motions reveal the inhomogeneous magnetic field of the solar corona. We show how these motions constrain field and plasma properties along the trajectory, and how they can be used to meaningfully distinguish between two classes of magnetic field models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Downs, Cooper -- Linker, Jon A -- Mikii, Zoran -- Riley, Pete -- Schrijver, Carolus J -- Saint-Hilaire, Pascal -- New York, N.Y. -- Science. 2013 Jun 7;340(6137):1196-9. doi: 10.1126/science.1236550.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Predictive Science Inc., San Diego, CA 92121, USA. cdowns@predsci.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23744941" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
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  • 9
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    Factors Affecting the Geo-effectiveness of Shocks and Sheaths at 1 AU (2016)
    Wiley
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    Publikationsdatum: 2016-10-30
    Beschreibung: We identify all fast-mode forward shocks, whose sheath regions resulted in a moderate (56 cases) or intense (38 cases) geomagnetic storm during 18.5 years from January 1997 to June 2015. We study their main properties, interplanetary causes and geo-effects. We find that half (49/94) such shocks are associated with interacting coronal mass ejections (CMEs), as they are either shocks propagating into a preceding CME (35 cases) or a shock propagating into the sheath region of a preceding shock (14 cases). About half (22/45) of the shocks driven by isolated transients and which have geo-effective sheaths compress pre-existing southward B z . Most of the remaining sheaths appear to have planar structures with southward magnetic fields, including some with planar structures consistent with field line draping ahead of the magnetic ejecta. A typical (median) geo-effective shock-sheath structure drives a geomagnetic storm with peak Dst of −88 nT, pushes the subsolar magnetopause location to 6.3 R E , i.e. below geosynchronous orbit and is associated with substorms with a peak AL-index of −1350 nT. There are some important differences between sheaths associated with CME-CME interaction (stronger storms) and those associated with isolated CMEs (stronger compression of the magnetosphere). We detail six case studies of different types of geo-effective shock-sheaths, as well as two events for which there was no geomagnetic storm but other magnetospheric effects. Finally, we discuss our results in terms of space weather forecasting, and potential effects on Earth's radiation belts.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 10
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    Overproduction and elimination of retinal axons in the fetal rhesus monkey (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1983-03-25
    Beschreibung: Quantitative electron microscopic analysis reveals 2.85 million retinal axons in fetal rhesus monkeys--a number that is more than twice the 1.2 million present in the adult. More than 1 million supernumerary optic axons are eliminated before birth, simultaneously with the segregation of inputs from the two eyes into separate layers of the lateral geniculate nucleus. Selective elimination of optic axons may not only play a role in the segregation of binocular visual connections but, secondarily, may establish the ratio of crossed and uncrossed retinogeniculate projections.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rakic, P -- Riley, K P -- EY02593/EY/NEI NIH HHS/ -- RR00168/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1983 Mar 25;219(4591):1441-4.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6828871" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Axons/*physiology/ultrastructure ; Female ; Fetus/physiology ; Macaca mulatta ; Optic Nerve/*embryology/ultrastructure ; Pregnancy ; Retina/*embryology/ultrastructure
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
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