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Sample records for enhanced geomagnetic activity

  1. Case study on total electron content enhancements at low latitudes during low geomagnetic activities before the storms

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    Libo Liu

    2008-05-01

    Full Text Available Sometimes the ionospheric total electron content (TEC is significantly enhanced during low geomagnetic activities before storms. In this article, we investigate the characteristics of those interesting TEC enhancements using regional and global TEC data. We analyzed the low-latitude TEC enhancement events that occurred around longitude 120° E on 10 February 2004, 21 January 2004, and 4 March 2001, respectively. The TEC data are derived from regional Global Positioning System (GPS observations in the Asia/Australia sector as well as global ionospheric maps (GIMs produced by Jet Propulsion Laboratory (JPL. Strong enhancements under low geomagnetic activity before the storms are simultaneously presented at low latitudes in the Asia/Australia sector in regional TEC and JPL GIMs. These TEC enhancements are shown to be regional events with longitudinal and latitudinal extent. The regions of TEC enhancements during these events are confined at narrow longitude ranges around longitude 120° E. The latitudinal belts of maxima of enhancements locate around the northern and southern equatorial ionization anomaly (EIA crests, which are consistent with those low-latitude events presented by Liu et al. (2008. During the 4 March 2001 event, the total plasma density Ni observed by the Defense Meteorological Satellite Program (DMSP spacecraft F13 at 840 km altitude are of considerably higher values on 4 March than on the previous day in the TEC enhanced regions. Some TEC enhancement events are possibly due to contributions from auroral/magnetospheric origins; while there are also quasi-periodic enhancement events not related to geomagnetic activity and associated probably with planetary wave type oscillations (e.g. the 6 January 1998 event. Further investigation is warrented to identify/separate contributions from possible sources.

  2. Solar wind and geomagnetism: toward a standard classification of geomagnetic activity from 1868 to 2009

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    J. L. Zerbo

    2012-02-01

    Full Text Available We examined solar activity with a large series of geomagnetic data from 1868 to 2009. We have revisited the geomagnetic activity classification scheme of Legrand and Simon (1989 and improve their scheme by lowering the minimum Aa index value for shock and recurrent activity from 40 to 20 nT. This improved scheme allows us to clearly classify about 80% of the geomagnetic activity in this time period instead of only 60% for the previous Legrand and Simon classification.

  3. Geomagnetic activity and the North Atlantic Oscillation

    Czech Academy of Sciences Publication Activity Database

    Bucha, Václav

    2014-01-01

    Roč. 58, č. 3 (2014), s. 461-472 ISSN 0039-3169 Institutional support: RVO:67985530 Keywords : geomagnetic activity * solar wind * polar vortex intensification * downward winds Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.806, year: 2014

  4. Relative outflow enhancements during major geomagnetic storms – Cluster observations

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    A. Schillings

    2017-12-01

    Full Text Available The rate of ion outflow from the polar ionosphere is known to vary by orders of magnitude, depending on the geomagnetic activity. However, the upper limit of the outflow rate during the largest geomagnetic storms is not well constrained due to poor spatial coverage during storm events. In this paper, we analyse six major geomagnetic storms between 2001 and 2004 using Cluster data. The six major storms fulfil the criteria of Dst  < −100 nT or Kp  > 7+. Since the shape of the magnetospheric regions (plasma mantle, lobe and inner magnetosphere are distorted during large magnetic storms, we use both plasma beta (β and ion characteristics to define a spatial box where the upward O+ flux scaled to an ionospheric reference altitude for the extreme event is observed. The relative enhancement of the scaled outflow in the spatial boxes as compared to the data from the full year when the storm occurred is estimated. Only O+ data were used because H+ may have a solar wind origin. The storm time data for most cases showed up as a clearly distinguishable separate peak in the distribution toward the largest fluxes observed. The relative enhancement in the outflow region during storm time is 1 to 2 orders of magnitude higher compared to less disturbed time. The largest relative scaled outflow enhancement is 83 (7 November 2004 and the highest scaled O+ outflow observed is 2  ×  1014 m−2 s−1 (29 October 2003.

  5. Ten cycles of solar and geomagnetic activity

    International Nuclear Information System (INIS)

    Legrand, J.P.

    1981-01-01

    Series of 110 years of sunspot numbers and indices of geomagnetic activity are used with 17 years of solar wind data in order to study through solar cycles both stream and shock event solar activity. According to their patterns on Bartels diagrams of geomagnetic indices, stable wind streams and transient solar activities are separated from each other. Two classes of stable streams are identified: equatorial streams occurring sporadically, for several months, during the main phase of sunspot cycles and both polar streams established, for several years, at each cycle, before sunspot minimum. Polar streams are the first activity of solar cycles. For study of the relationship between transient geomagnetic phenomena and sunspot activity, we raise the importance of the contribution, at high spot number, of severe storms and, at low spot number, of short lived and unstable streams. Solar wind data are used to check and complete the above results. As a conclusion, we suggest a unified scheme of solar activity evolution with a starting point every eleventh year, a total duration of 17 years and an overlapping of 6 years between the first and the last phase of both successive series of phenomena: first, from polar field reversal to sunspot minimum, a phase of polar wind activity of the beginning cycle is superimposed on the weak contribution of shock events of the ending cycle; secondly, an equatorial phase mostly of shock events is superimposed on a variable contribution of short lived and sporadic stable equatorial stream activities; and thirdly a phase of low latitude shock events is superimposed on the polar stream interval of the following cycle. (orig.)

  6. Geomagnetic activity and the global temperature

    Czech Academy of Sciences Publication Activity Database

    Bucha, Václav

    2009-01-01

    Roč. 53, č. 4 (2009), s. 571-573 ISSN 0039-3169 Institutional research plan: CEZ:AV0Z30120515 Keywords : global warming * Southern Oscillation * geomagnetic storms Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.000, year: 2009

  7. Green corona, geomagnetic activity and radar meteor rates

    International Nuclear Information System (INIS)

    Prikryl, P.

    1979-01-01

    The short-term dependence of radar meteor rates on geomagnetic activity and/or central meridian passage (CMP) of bright or faint green corona regions is studied. A superimposed-epoch analysis was applied to radar meteor observations from the Ottawa patrol radar (Springhill, Ont.) and Ksub(p)-indices of geomagnetic activity for the period 1963 to 1967. During the minimum of solar activity (1963 to 1965) the CMP of bright coronal regions was followed by the maximum in the daily rates of persistent meteor echoes (>=4s), and the minimum in the daily sums of Ksub(p)-indices whereas the minimum or the maximum, respectively, occurs after the CMP of faint coronal regions. The time delay between the CMP of coronal structures and the corresponding maxima or minima is found to be 3 to 4 days. However, for the period immediately after the minimum of solar activity (1966 to 1967) the above correlation with the green corona is void both for the geomagnetic activity and radar meteor rates. An inverse correlation was found between the radar meteor rates and the geomagnetic activity irrespective of the solar activity. The observed effect can be ascribed to the solar-wind-induced ''geomagnetic'' heating of the upper atmosphere and to the subsequent change in the density gradient in the meteor zone. (author)

  8. Effects of geomagnetic activity on the mesospheric electric fields

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    A. M. Zadorozhny

    Full Text Available The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes Kp and ∑Kp. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (Kp=8+. A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.

    Keywords. Atmospheric composition and structure (aerosols and particles · Ionosphere (electric fields and currents · Meteorology and atmospheric dynamics (atmospheric electricity

  9. Effects of geomagnetic activity on the mesospheric electric fields

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    A. M. Zadorozhny

    1998-12-01

    Full Text Available The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes Kp and ∑Kp. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (Kp=8+. A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.Keywords. Atmospheric composition and structure (aerosols and particles · Ionosphere (electric fields and currents · Meteorology and atmospheric dynamics (atmospheric electricity

  10. Statistical Properties of Geomagnetic Activity Indices and Solar Wind Parameters

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    Jung-Hee Kim

    2014-06-01

    Full Text Available As the prediction of geomagnetic storms is becoming an important and practical problem, conditions in the Earth’s magnetosphere have been studied rigorously in terms of those in the interplanetary space. Another approach to space weather forecast is to deal with it as a probabilistic geomagnetic storm forecasting problem. In this study, we carry out detailed statistical analysis of solar wind parameters and geomagnetic indices examining the dependence of the distribution on the solar cycle and annual variations. Our main findings are as follows: (1 The distribution of parameters obtained via the superimposed epoch method follows the Gaussian distribution. (2 When solar activity is at its maximum the mean value of the distribution is shifted to the direction indicating the intense environment. Furthermore, the width of the distribution becomes wider at its maximum than at its minimum so that more extreme case can be expected. (3 The distribution of some certain heliospheric parameters is less sensitive to the phase of the solar cycle and annual variations. (4 The distribution of the eastward component of the interplanetary electric field BV and the solar wind driving function BV2, however, appears to be all dependent on the solar maximum/minimum, the descending/ascending phases of the solar cycle and the equinoxes/solstices. (5 The distribution of the AE index and the Dst index shares statistical features closely with BV and BV2 compared with other heliospheric parameters. In this sense, BV and BV2 are more robust proxies of the geomagnetic storm. We conclude by pointing out that our results allow us to step forward in providing the occurrence probability of geomagnetic storms for space weather and physical modeling.

  11. Geomagnetic activity effects on plasma sheet energy conversion

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    M. Hamrin

    2010-10-01

    Full Text Available In this article we use three years (2001, 2002, and 2004 of Cluster plasma sheet data to investigate what happens to localized energy conversion regions (ECRs in the plasma sheet during times of high magnetospheric activity. By examining variations in the power density, E·J, where E is the electric field and J is the current density obtained by Cluster, we have studied the influence on Concentrated Load Regions (CLRs and Concentrated Generator Regions (CGRs from variations in the geomagnetic disturbance level as expressed by the Kp, the AE, and the Dst indices. We find that the ECR occurrence frequency increases during higher magnetospheric activities, and that the ECRs become stronger. This is true both for CLRs and for CGRs, and the localized energy conversion therefore concerns energy conversion in both directions between the particles and the fields in the plasma sheet. A higher geomagnetic activity hence increases the general level of energy conversion in the plasma sheet. Moreover, we have shown that CLRs live longer during magnetically disturbed times, hence converting more electromagnetic energy. The CGR lifetime, on the other hand, seems to be unaffected by the geomagnetic activity level. The evidence for increased energy conversion during geomagnetically disturbed times is most clear for Kp and for AE, but there are also some indications that energy conversion increases during large negative Dst. This is consistent with the plasma sheet magnetically mapping to the auroral zone, and therefore being more tightly coupled to auroral activities and variations in the AE and Kp indices, than to variations in the ring current region as described by the Dst index.

  12. Forecasting intense geomagnetic activity using interplanetary magnetic field data

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    Saiz, E.; Cid, C.; Cerrato, Y.

    2008-12-01

    Southward interplanetary magnetic fields are considered traces of geoeffectiveness since they are a main agent of magnetic reconnection of solar wind and magnetosphere. The first part of this work revises the ability to forecast intense geomagnetic activity using different procedures available in the literature. The study shows that current methods do not succeed in making confident predictions. This fact led us to develop a new forecasting procedure, which provides trustworthy results in predicting large variations of Dst index over a sample of 10 years of observations and is based on the value Bz only. The proposed forecasting method appears as a worthy tool for space weather purposes because it is not affected by the lack of solar wind plasma data, which usually occurs during severe geomagnetic activity. Moreover, the results obtained guide us to provide a new interpretation of the physical mechanisms involved in the interaction between the solar wind and the magnetosphere using Faraday's law.

  13. Geophysical variables and behavior: XXI. Geomagnetic variation as possible enhancement stimuli for UFO reports preceding earthtremors.

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    Persinger, M A

    1985-02-01

    The contribution of geomagnetic variation to the occurrence of UFORs (reports of UFOs) within the New Madrid States during the 6-mo. increments before increases in the numbers of IV-V or less intensity earthquakes within the central USA was determined. Although statistically significant zero-order correlations existed between measures of earthquakes, UFORs and geomagnetic variability, the association between the latter two deteriorated markedly when their shared variance with earthquakes was held constant. These outcomes are compatible with the hypothesis that geomagnetic variability (or phenomena associated with it) may enhance UFORs but only if tectonic stress and strain are increasing within the region.

  14. Recent Activities Of The World Data Centre For Geomagnetism (Edinburgh)

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    Reay, Sarah; Humphries, Tom; Macmillan, Susan; Flower, Simon; Stevenson, Peter; Clarke, Ellen

    2015-01-01

    For almost 50 years the World Data Centre for Geomagnetism (Edinburgh) has been a custodian of geomagnetic data. In particular, over recent years the scope of the data holdings has been increased, quality control measures introduced and better interfaces to make the data more accessible to users are being developed. The WDC hold geomagnetic time-series data from around 280 observatories worldwide at a number of time resolutions along with various magnetic survey, model, and geomagnetic ac...

  15. Spectral Analysis of Geomagnetic Activity Indices and Solar Wind Parameters

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    Jung-Hee Kim

    2014-06-01

    Full Text Available Solar variability is widely known to affect the interplanetary space and in turn the Earth’s electromagnetical environment on the basis of common periodicities in the solar and geomagnetic activity indices. The goal of this study is twofold. Firstly, we attempt to associate modes by comparing a temporal behavior of the power of geomagnetic activity parameters since it is barely sufficient searching for common peaks with a similar periodicity in order to causally correlate geomagnetic activity parameters. As a result of the wavelet transform analysis we are able to obtain information on the temporal behavior of the power in the velocity of the solar wind, the number density of protons in the solar wind, the AE index, the Dst index, the interplanetary magnetic field, B and its three components of the GSM coordinate system, BX, BY, BZ. Secondly, we also attempt to search for any signatures of influence on the space environment near the Earth by inner planets orbiting around the Sun. Our main findings are as follows: (1 Parameters we have investigated show periodicities of ~ 27 days, ~ 13.5 days, ~ 9 days. (2 The peaks in the power spectrum of BZ appear to be split due to an unknown agent. (3 For some modes powers are not present all the time and intervals showing high powers do not always coincide. (4 Noticeable peaks do not emerge at those frequencies corresponding to the synodic and/or sidereal periods of Mercury and Venus, which leads us to conclude that the Earth’s space environment is not subject to the shadow of the inner planets as suggested earlier.

  16. Lessons learned from recent geomagnetic disturbance model validation activities

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    Pulkkinen, A. A.; Welling, D. T.

    2017-12-01

    Due to concerns pertaining to geomagnetically induced current impact on ground-based infrastructure, there has been significantly elevated interest in applying models for local geomagnetic disturbance or "delta-B" predictions. Correspondingly there has been elevated need for testing the quality of the delta-B predictions generated by the modern empirical and physics-based models. To address this need, community-wide activities were launched under the GEM Challenge framework and one culmination of the activities was the validation and selection of models that were transitioned into operations at NOAA SWPC. The community-wide delta-B action is continued under the CCMC-facilitated International Forum for Space Weather Capabilities Assessment and its "Ground Magnetic Perturbations: dBdt, delta-B, GICs, FACs" working group. The new delta-B working group builds on the past experiences and expands the collaborations to cover the entire international space weather community. In this paper, we discuss the key lessons learned from the past delta-B validation exercises and lay out the path forward for building on those experience under the new delta-B working group.

  17. Associations of geomagnetic activity with plasma sheet thinning and expansion: A statistical study

    International Nuclear Information System (INIS)

    Hones, E.W. Jr.; Pytte, T.; West, H.I. Jr.

    1984-01-01

    Associations of geomagnetic activity in the auroral zone with thinnings and expansions of the magnetotail plasma sheet are examined statistically in this paper. We first identified many plasma sheet thinnings and expansions in plasma and particle data from VELA satellites and from OGO 5 without reference to the ground magnetic data. These events were grouped according to the location of the detecting satellite in the magnetotail. For each such group the times of thinning or expansion were then used as fiducial times in a superposed-epoch analysis of the geomagnetic AL index values that were recorded in 8-hour intervals centered on the event times. The results show that many plasma sheet thinnings and expansions are related to discrete negative bay structures that are the classical signature of substorms. Furthermore, they support earlier findings that plasma sheet thinning and expansion at the VELA orbit (rroughly-equal18 R/sub E/) tend to be associated with the onset of the auroral zone negative bay and the beginning of its subsidence, respectively. Earthward of rroughly-equal13-15 R/sub E/, plasma sheet expansion occurs near the time of the onset of the negative bay, again in agreement with earlier findings. A large fraction of plasma sheet expansions to half thicknesses of > or approx. =6 R/sub E/ at the VELA orbit are associated not with a baylike geomagnetic disturbance but with subsidence of a prolonged interval of disturbance. The study also shows that many plasma sheet expansions are related simply to generally enhanced geomagnetic activity showing no baylike or other distinctive features

  18. Latitude dependence of long-term geomagnetic activity and its solar wind drivers

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    Myllys, M. [Helsinki Univ. (Finland). Dept. of Physics; Partamies, N. [Finnish Meteorological Institute, Helsinki (Finland); University Centre in Svalbard, Longyearbyen (Norway). Dept. of Arctic Geophysics; Juusola, L. [Finnish Meteorological Institute, Helsinki (Finland)

    2015-09-01

    To validate the usage of global indices in studies of geomagnetic activity, we have examined the latitude dependence of geomagnetic variations in Fennoscandia and Svalbard from 1994 to 2010. Daily standard deviation (SD) values of the horizontal magnetic field have been used as a measure of the ground magnetic disturbance level.We found that the timing of the geomagnetic minimum depends on the latitude region: corresponding to the minimum of sunspot cycle 22 (in 1996), the geomagnetic minimum occurred between the geomagnetic latitudes 57-61 in 1996 and at the latitudes 64-67 in 1997, which are the average auroral oval latitudes. During sunspot cycle 23, all latitude regions experienced the minimum in 2009, a year after the sunspot minimum. These timing differences are due to the latitude dependence of the 10 s daily SD on the different solar wind drivers. In the latitude region of 64-67 , the impact of the high-speed solar wind streams (HSSs) on the geomagnetic activity is the most pronounced compared to the other latitude groups, while in the latitude region of 57-61 , the importance of the coronal mass ejections (CMEs) dominates. The geomagnetic activity maxima during ascending solar cycle phases are typically caused by CME activity and occur especially in the oval and sub-auroral regions. The strongest geomagnetic activity occurs during the descending solar cycle phases due to a mixture of CME and HSS activity. Closer to the solar minimum, less severe geomagnetic activity is driven by HSSs and mainly visible in the poleward part of the auroral region. According to our study, however, the timing of the geomagnetic activity minima (and maxima) in different latitude bands is different, due to the relative importance of different solar wind drivers at different latitudes.

  19. Latitude dependence of long-term geomagnetic activity and its solar wind drivers

    International Nuclear Information System (INIS)

    Myllys, M.

    2015-01-01

    To validate the usage of global indices in studies of geomagnetic activity, we have examined the latitude dependence of geomagnetic variations in Fennoscandia and Svalbard from 1994 to 2010. Daily standard deviation (SD) values of the horizontal magnetic field have been used as a measure of the ground magnetic disturbance level.We found that the timing of the geomagnetic minimum depends on the latitude region: corresponding to the minimum of sunspot cycle 22 (in 1996), the geomagnetic minimum occurred between the geomagnetic latitudes 57-61 in 1996 and at the latitudes 64-67 in 1997, which are the average auroral oval latitudes. During sunspot cycle 23, all latitude regions experienced the minimum in 2009, a year after the sunspot minimum. These timing differences are due to the latitude dependence of the 10 s daily SD on the different solar wind drivers. In the latitude region of 64-67 , the impact of the high-speed solar wind streams (HSSs) on the geomagnetic activity is the most pronounced compared to the other latitude groups, while in the latitude region of 57-61 , the importance of the coronal mass ejections (CMEs) dominates. The geomagnetic activity maxima during ascending solar cycle phases are typically caused by CME activity and occur especially in the oval and sub-auroral regions. The strongest geomagnetic activity occurs during the descending solar cycle phases due to a mixture of CME and HSS activity. Closer to the solar minimum, less severe geomagnetic activity is driven by HSSs and mainly visible in the poleward part of the auroral region. According to our study, however, the timing of the geomagnetic activity minima (and maxima) in different latitude bands is different, due to the relative importance of different solar wind drivers at different latitudes.

  20. Origins of the semiannual variation of geomagnetic activity in 1954 and 1996

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    L. Svalgaard

    Full Text Available We investigate the cause of the unusually strong semiannual variation of geomagnetic activity observed in the solar minimum years of 1954 and 1996. For 1996 we separate the contributions of the three classical modulation mechanisms (axial, equinoctial, and Russell-McPherron to the six-month wave in the aam index and find that all three contribute about equally. This is in contrast to the longer run of geomagnetic activity (1868-1998 over which the equinoctial effect accounts for ∼70% of the semiannual variation. For both 1954 and 1996, we show that the Russell-McPherron effect was enhanced by the Rosenberg-Coleman effect (an axial polarity effect which increased the amount of the negative (toward Sun [positive (away from Sun] polarity field observed during the first [second] half of the year; such fields yield a southward component in GSM coordinates. Because this favourable condition occurs only for alternate solar cycles, the marked semiannual variation in 1954 and 1996 is a manifestation of the 22-year cycle of geomagnetic activity. The 11-year evolution of the heliospheric current sheet (HCS also contributes to the strong six-month wave during these years. At solar minimum, the streamer belt at the base of the HCS is located near the solar equator, permitting easier access to high speed streams from polar coronal holes when the Earth is at its highest heliographic latitudes in March and September. Such an axial variation in solar wind speed was observed for 1996 and is inferred for 1954. Key words. Magnetosphere (solar wind – magnetosphere interactions; storms and substorms

  1. Origins of the semiannual variation of geomagnetic activity in 1954 and 1996

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    E. W. Cliver

    2004-01-01

    Full Text Available We investigate the cause of the unusually strong semiannual variation of geomagnetic activity observed in the solar minimum years of 1954 and 1996. For 1996 we separate the contributions of the three classical modulation mechanisms (axial, equinoctial, and Russell-McPherron to the six-month wave in the aam index and find that all three contribute about equally. This is in contrast to the longer run of geomagnetic activity (1868-1998 over which the equinoctial effect accounts for ∼70% of the semiannual variation. For both 1954 and 1996, we show that the Russell-McPherron effect was enhanced by the Rosenberg-Coleman effect (an axial polarity effect which increased the amount of the negative (toward Sun [positive (away from Sun] polarity field observed during the first [second] half of the year; such fields yield a southward component in GSM coordinates. Because this favourable condition occurs only for alternate solar cycles, the marked semiannual variation in 1954 and 1996 is a manifestation of the 22-year cycle of geomagnetic activity. The 11-year evolution of the heliospheric current sheet (HCS also contributes to the strong six-month wave during these years. At solar minimum, the streamer belt at the base of the HCS is located near the solar equator, permitting easier access to high speed streams from polar coronal holes when the Earth is at its highest heliographic latitudes in March and September. Such an axial variation in solar wind speed was observed for 1996 and is inferred for 1954. Key words. Magnetosphere (solar wind – magnetosphere interactions; storms and substorms

  2. Quantitative modeling of the ionospheric response to geomagnetic activity

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    T. J. Fuller-Rowell

    Full Text Available A physical model of the coupled thermosphere and ionosphere has been used to determine the accuracy of model predictions of the ionospheric response to geomagnetic activity, and assess our understanding of the physical processes. The physical model is driven by empirical descriptions of the high-latitude electric field and auroral precipitation, as measures of the strength of the magnetospheric sources of energy and momentum to the upper atmosphere. Both sources are keyed to the time-dependent TIROS/NOAA auroral power index. The output of the model is the departure of the ionospheric F region from the normal climatological mean. A 50-day interval towards the end of 1997 has been simulated with the model for two cases. The first simulation uses only the electric fields and auroral forcing from the empirical models, and the second has an additional source of random electric field variability. In both cases, output from the physical model is compared with F-region data from ionosonde stations. Quantitative model/data comparisons have been performed to move beyond the conventional "visual" scientific assessment, in order to determine the value of the predictions for operational use. For this study, the ionosphere at two ionosonde stations has been studied in depth, one each from the northern and southern mid-latitudes. The model clearly captures the seasonal dependence in the ionospheric response to geomagnetic activity at mid-latitude, reproducing the tendency for decreased ion density in the summer hemisphere and increased densities in winter. In contrast to the "visual" success of the model, the detailed quantitative comparisons, which are necessary for space weather applications, are less impressive. The accuracy, or value, of the model has been quantified by evaluating the daily standard deviation, the root-mean-square error, and the correlation coefficient between the data and model predictions. The modeled quiet-time variability, or standard

  3. Quantitative modeling of the ionospheric response to geomagnetic activity

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    T. J. Fuller-Rowell

    2000-07-01

    Full Text Available A physical model of the coupled thermosphere and ionosphere has been used to determine the accuracy of model predictions of the ionospheric response to geomagnetic activity, and assess our understanding of the physical processes. The physical model is driven by empirical descriptions of the high-latitude electric field and auroral precipitation, as measures of the strength of the magnetospheric sources of energy and momentum to the upper atmosphere. Both sources are keyed to the time-dependent TIROS/NOAA auroral power index. The output of the model is the departure of the ionospheric F region from the normal climatological mean. A 50-day interval towards the end of 1997 has been simulated with the model for two cases. The first simulation uses only the electric fields and auroral forcing from the empirical models, and the second has an additional source of random electric field variability. In both cases, output from the physical model is compared with F-region data from ionosonde stations. Quantitative model/data comparisons have been performed to move beyond the conventional "visual" scientific assessment, in order to determine the value of the predictions for operational use. For this study, the ionosphere at two ionosonde stations has been studied in depth, one each from the northern and southern mid-latitudes. The model clearly captures the seasonal dependence in the ionospheric response to geomagnetic activity at mid-latitude, reproducing the tendency for decreased ion density in the summer hemisphere and increased densities in winter. In contrast to the "visual" success of the model, the detailed quantitative comparisons, which are necessary for space weather applications, are less impressive. The accuracy, or value, of the model has been quantified by evaluating the daily standard deviation, the root-mean-square error, and the correlation coefficient between the data and model predictions. The modeled quiet-time variability, or standard

  4. Influence of geomagnetic activity and atmospheric pressure in hypertensive adults.

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    Azcárate, T; Mendoza, B

    2017-09-01

    We performed a study of the systolic and diastolic arterial blood pressure behavior under natural variables such as the atmospheric pressure and the horizontal geomagnetic field component. We worked with a group of eight adult hypertensive volunteers, four men and four women, with ages between 18 and 27 years in Mexico City during a geomagnetic storm in 2014. The data was divided by gender, age, and day/night cycle. We studied the time series using three methods: correlations, bivariate analysis, and superposed epoch (within a window of 2 days around the day of occurrence of a geomagnetic storm) analysis, between the systolic and diastolic blood pressure and the natural variables. The correlation analysis indicated a correlation between the systolic and diastolic blood pressure and the atmospheric pressure and the horizontal geomagnetic field component, being the largest during the night. Furthermore, the correlation and bivariate analyses showed that the largest correlations are between the systolic and diastolic blood pressure and the horizontal geomagnetic field component. Finally, the superposed epoch analysis showed that the largest number of significant changes in the blood pressure under the influence of geomagnetic field occurred in the systolic blood pressure for men.

  5. Influence of geomagnetic activity and atmospheric pressure in hypertensive adults

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    Azcárate, T.; Mendoza, B.

    2017-09-01

    We performed a study of the systolic and diastolic arterial blood pressure behavior under natural variables such as the atmospheric pressure and the horizontal geomagnetic field component. We worked with a group of eight adult hypertensive volunteers, four men and four women, with ages between 18 and 27 years in Mexico City during a geomagnetic storm in 2014. The data was divided by gender, age, and day/night cycle. We studied the time series using three methods: correlations, bivariate analysis, and superposed epoch (within a window of 2 days around the day of occurrence of a geomagnetic storm) analysis, between the systolic and diastolic blood pressure and the natural variables. The correlation analysis indicated a correlation between the systolic and diastolic blood pressure and the atmospheric pressure and the horizontal geomagnetic field component, being the largest during the night. Furthermore, the correlation and bivariate analyses showed that the largest correlations are between the systolic and diastolic blood pressure and the horizontal geomagnetic field component. Finally, the superposed epoch analysis showed that the largest number of significant changes in the blood pressure under the influence of geomagnetic field occurred in the systolic blood pressure for men.

  6. Geomagnetic activity associated with Earth passage of interplanetary shock disturbances and coronal mass ejections

    International Nuclear Information System (INIS)

    Gosling, J.T.; McComas, D.J.; Phillips, J.L.; Bame, S.J.

    1991-01-01

    Previous work indicates that virtually all transient shock wave disturbances in the solar wind are driven by fast coronal mass ejection events (CMEs). Using a recently appreciated capability for distinguishing CMEs in solar wind data in the form of counterstreaming solar wind electron events, this paper explores the overall effectiveness of shock wave disturbances and CMEs in general in stimulating geomagnetic activity. The study is confined to the interval from mid-August 1978 through mid-October 1982, spanning the last solar activity maximum, when ISEE 3 was in orbit about the L1 Lagrange point 220 R e upstream from Earth. The authors find that all but one of the 37 largest geomagnetic storms in that era were associated with Earth passage of CMEs and/or shock disturbances, with the large majority of these storms being associated with interplanetary events where Earth encountered both a shock and the CME driving the shock (shock/CME events). Although CMEs and/or shock disturbances were increasingly the cause of geomagnetic activity as the level of geomagnetic activity increased, many smaller geomagnetic disturbances were unrelated to these events. Further, approximately half of all CMEs and half of all shock disturbances encountered by Earth did not produce any substantial geomagnetic activity as measured by the planetary geomagnetic index Kp. The geomagnetic effectiveness of Earth directed CMEs and shock wave disturbances was directly related to the flow speed, the magnetic field magnitude, and the strength of the southward (GSM) field component associated with the events. The initial speed of a CME close to the Sun appears to be the most crucial factor in determining if an earthward directed event will be effective in exciting a large geomagnetic disturbance

  7. Long-term variations in the geomagnetic activity level Part II: Ascending phases of sunspot cycles

    Directory of Open Access Journals (Sweden)

    V. Mussino

    1994-08-01

    Full Text Available Monthly averages of the Helsinki Ak-values have been reduced to the equivalent aa-indices to extend the aa-data set back to 1844. A periodicity of about five cycles was found for the correlation coefficient (r between geomagnetic indices and sunspot numbers for the ascending phases of sunspot cycles 9 to 22, confirming previous findings based on a minor number of sunspot cycles. The result is useful to researchers in topics related to solar-terrestrial physics, particularly for the interpretation of long-term trends in geomagnetic activity during the past, and to forecast geomagnetic activity levels in the future.

  8. Correlation of geomagnetic activity with implantable cardioverter defibrillator shocks and antitachycardia pacing

    Czech Academy of Sciences Publication Activity Database

    Ebrille, E.; Konecny, T.; Konecny, D.; Špaček, R.; Jones, P.; Ambrož, Pavel; DeSimone, C.V.; Powel, B.D.; Hayes, D.L.; Friedman, P.A.; Asirvatham, S.J.

    2015-01-01

    Roč. 90, č. 2 (2015), s. 202-208 ISSN 0025-6196 Institutional support: RVO:67985815 Keywords : geomagnetic activity * implantable cardioverter defibrillator Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 5.920, year: 2015

  9. Enhancement of low energy particle flux around plasmapause under quiet geomagnetic condition

    Science.gov (United States)

    Lee, J.

    2016-12-01

    Plasmapause is the boundary of the plasmaspheric region where cold plasma is dominant. In this boundary, the plasma density shows depletion to 1 10 on direction from the plasmasphere to magnetosphere and changes composition of energy distribution of particle. Some previous study provides that the location of the plasmapause expand beyond geosynchronous orbit under the quiet geomagnetic conditions. In this work, we study the changed characteristic of particle flux around the plasmapause using measurement from Van Allen Probes. On 23 April 2013, the satellites observed simultaneously proton and electron fluxes enhancement with E > 100 eV. During 12 hours prior to this event, the geomagnetic conditions were very quiet, Kp < 1, and geomagnetic storm did not occur. This event maintain for 15 minutes and only proton flux decrease rapidly in the magnetosphere. In this period SYM-H index enhanced abruptly in response to the impact of the dynamic pressure enhancement and AE index increased gradually up to about 200 nT. Electric field started to perturb in coincidence with enhancement of particle flux from the plasmapause. To explain the variation of low energy particle flux we will compare kinetic property of low energy particle by using velocity space distribution function at region of inner and outer boundary of the plasmapause.

  10. Comment on ``Annual variation of geomagnetic activity'' by Alicia L. Clúa de Gonzales et al.

    Science.gov (United States)

    Sonnemann, G. R.

    2002-10-01

    Clúa de Gonzales et al. (J. Atmos. Terr. Phys. 63 (2001) 367) analyzed the monthly means of the geomagnetic /aa-index available since 1868 and found enhanced geomagnetic activity in July outside of the known seasonal course of semiannual variation. They pointed out that this behavior is mainly caused by the high values of the geomagnetic activity. Their analysis confirmed results obtained from an analysis of Ap-values nearly 30 years ago but widely unknown to the scientific community. At that time the entire year was analyzed using running means of the activity values averaged to the same date. Aside from the July period, the calculations revealed distinct deviations from the seasonal course-called geomagnetic singularities. The most marked singularity occurs from the middle of March to the end of March characterized by a strong increase from, on average, relatively calm values to the actually strongest ones during the entire year. Some typical time patterns around and after equinox are repeated half a year later. An analysis in 1998 on the basis of the available /aa-values confirmed the findings derived from Ap-values and the local activity index Ak from Niemegk, Germany available since 1890. The new results will be presented and discussed. Special attention is paid to the statistical problem of the persistence of geomagnetic perturbations. The main problem under consideration is that the variation of the mean activity is not caused by an accidental accumulation of strong perturbations occurring within certain intervals of days. We assume that the most marked variations of the mean value are not accidental and result from internal processes within the earth's atmosphere but different, particularly small-scale features, are most probably accidental.

  11. An association between geomagnetic activity and dream bizarreness.

    Science.gov (United States)

    Lipnicki, Darren M

    2009-07-01

    Daily disturbances of the earth's magnetic field produce variations in geomagnetic activity (GMA) that are reportedly associated with widespread effects on human health and behaviour. Some of these effects could be mediated by an established influence of GMA on the secretion of melatonin. There is evidence from unrelated research that melatonin influences dream bizarreness, and it is hypothesised here that there is an association between GMA and dream bizarreness. Also reported is a preliminary test of this hypothesis, a case study in which the dreams recorded over 6.5 years by a young adult male were analysed. Reports of dreams from the second of two consecutive days of either low or high GMA (K index sum or = 28) were self-rated for bizarreness on a 1-5 scale. Dreams from low GMA periods (n=69, median bizarreness=4) were found to be significantly more bizarre than dreams from high GMA periods (n=85, median bizarreness=3; p=0.006), supporting the hypothesised association between GMA and dream bizarreness. Studies with larger samples are needed to verify this association, and to determine the extent to which melatonin may be involved. Establishing that there is an association between GMA and dream bizarreness would have relevance for neurophysiological theories of dreaming, and for models of psychotic symptoms resembling bizarre dream events.

  12. Innovative techniques to analyze time series of geomagnetic activity indices

    Science.gov (United States)

    Balasis, Georgios; Papadimitriou, Constantinos; Daglis, Ioannis A.; Potirakis, Stelios M.; Eftaxias, Konstantinos

    2016-04-01

    Magnetic storms are undoubtedly among the most important phenomena in space physics and also a central subject of space weather. The non-extensive Tsallis entropy has been recently introduced, as an effective complexity measure for the analysis of the geomagnetic activity Dst index. The Tsallis entropy sensitively shows the complexity dissimilarity among different "physiological" (normal) and "pathological" states (intense magnetic storms). More precisely, the Tsallis entropy implies the emergence of two distinct patterns: (i) a pattern associated with the intense magnetic storms, which is characterized by a higher degree of organization, and (ii) a pattern associated with normal periods, which is characterized by a lower degree of organization. Other entropy measures such as Block Entropy, T-Complexity, Approximate Entropy, Sample Entropy and Fuzzy Entropy verify the above mentioned result. Importantly, the wavelet spectral analysis in terms of Hurst exponent, H, also shows the existence of two different patterns: (i) a pattern associated with the intense magnetic storms, which is characterized by a fractional Brownian persistent behavior (ii) a pattern associated with normal periods, which is characterized by a fractional Brownian anti-persistent behavior. Finally, we observe universality in the magnetic storm and earthquake dynamics, on a basis of a modified form of the Gutenberg-Richter law for the Tsallis statistics. This finding suggests a common approach to the interpretation of both phenomena in terms of the same driving physical mechanism. Signatures of discrete scale invariance in Dst time series further supports the aforementioned proposal.

  13. Geomagnetic activity forcing of the Northern Annular Mode via the stratosphere

    Directory of Open Access Journals (Sweden)

    D. R. Palamara

    2004-03-01

    Full Text Available We consider various aspects of the link between solar-modulated geomagnetic activity and the Northern Annular Mode (NAM. Our results indicate that the geomagnetic forcing of atmospheric circulation in the Northern Hemisphere is temporally and seasonally restricted, modulated by the Quasi-Biennial Oscillation (QBO, and reliant on stratosphere-troposphere coupling. When the data are restricted to January values after 1965, for years in which the January QBO is eastwards, the correlation coefficient between the geomagnetic AA index and the NAM is 0.85. These results can account for many of the enigmatic features of Northern Hemisphere circulation. Key words. Meterology and atmospheric dynamics (general circulation, climatology

  14. The Challenge Posed by Geomagnetic Activity to Electric Power Reliability: Evidence From England and Wales

    Science.gov (United States)

    Forbes, Kevin F.; St. Cyr, O. C.

    2017-10-01

    This paper addresses whether geomagnetic activity challenged the reliability of the electric power system during part of the declining phase of solar cycle 23. Operations by National Grid in England and Wales are examined over the period of 11 March 2003 through 31 March 2005. This paper examines the relationship between measures of geomagnetic activity and a metric of challenged electric power reliability known as the net imbalance volume (NIV). Measured in megawatt hours, NIV represents the sum of all energy deployments initiated by the system operator to balance the electric power system. The relationship between geomagnetic activity and NIV is assessed using a multivariate econometric model. The model was estimated using half-hour settlement data over the period of 11 March 2003 through 31 December 2004. The results indicate that geomagnetic activity had a demonstrable effect on NIV over the sample period. Based on the parameter estimates, out-of-sample predictions of NIV were generated for each half hour over the period of 1 January to 31 March 2005. Consistent with the existence of a causal relationship between geomagnetic activity and the electricity market imbalance, the root-mean-square error of the out-of-sample predictions of NIV is smaller; that is, the predictions are more accurate, when the statistically significant estimated effects of geomagnetic activity are included as drivers in the predictions.

  15. Long-term trends of foE and geomagnetic activity variations

    Directory of Open Access Journals (Sweden)

    A. V. Mikhailov

    2003-03-01

    Full Text Available A relationship between foE trends and geomagnetic activity long-term variations has been revealed for the first time. By analogy with earlier obtained results on the foF2 trends it is possible to speak about the geomagnetic control of the foE long-term trends as well. Periods of increasing geomagnetic activity correspond to negative foE trends, while these trends are positive for the decreasing phase of geomagnetic activity. This "natural" relationship breaks down around 1970 (on some stations later when pronounced positive foE trends have appeared on most of the stations considered. The dependence of foE trends on geomagnetic activity can be related with nitric oxide variations at the E-layer heights. The positive foE trends that appeared after the "break down" effect may also be explained by the [NO] decrease which is not related to geomagnetic activity variations. But negative trends or irregular foE variations on some stations for the same time period require some different mechanism. Chemical pollution of the lower thermosphere due to the anthropogenic activity may be responsible for such abnormal foE behavior after the end of the 1960s.Key words. Ionosphere (ionosphere-atmosphere interactions; ionospheric disturbances

  16. Time variations of geomagnetic activity indices Kp and Ap: an update

    Directory of Open Access Journals (Sweden)

    G. K. Rangarajan

    1997-10-01

    Full Text Available Kp and Ap indices covering the period 1932 to 1995 are analysed in a fashion similar to that attempted by Bartels for the 1932–1961 epoch to examine the time variations in their characteristics. Modern analysis techniques on the extended data base are used for further insight. The relative frequencies of occurrence of Kp with different magnitudes and the seasonal and solar cycle dependences are seen to be remarkably consistent despite the addition of 35 years of observations. Many of the earlier features seen in the indices and special intervals are shown to be replicated in the present analysis. Time variations in the occurrence of prolonged periods of geomagnetic calm or of enhanced activity are presented and their relation to solar activity highlighted. It is shown that in the declining phase the occurrence frequencies of Kp = 4–5 (consecutively over 4 intervals can be used as a precursor for the maximum sunspot number to be expected in the next cycle. The semi-annual variation in geomagnetic activity is re-examined utilising not only the Ap index but also the occurrence frequencies of Kp index with different magnitudes. Lack of dependence of the amplitude of semi-annual variation on sunspot number is emphasised. Singular spectrum analysis of the mean monthly Ap index shows some distinct periodic components. The temporal evolution of ~44 month, ~21 month and ~16 month oscillations are examined and it is postulated that while QBO and the 16 month oscillations could be attributed to solar wind and IMF oscillations with analogous periodicity, the 44 month variation is associated with a similar periodicity in recurrent high speed stream caused by sector boundary passage. It is reconfirmed that there could have been only one epoch around 1940 when solar wind speed could have exhibited a 1.3-year periodicity comparable to that seen during the post-1986 period.

  17. Time variations of geomagnetic activity indices Kp and Ap: an update

    Directory of Open Access Journals (Sweden)

    G. K. Rangarajan

    Full Text Available Kp and Ap indices covering the period 1932 to 1995 are analysed in a fashion similar to that attempted by Bartels for the 1932–1961 epoch to examine the time variations in their characteristics. Modern analysis techniques on the extended data base are used for further insight. The relative frequencies of occurrence of Kp with different magnitudes and the seasonal and solar cycle dependences are seen to be remarkably consistent despite the addition of 35 years of observations. Many of the earlier features seen in the indices and special intervals are shown to be replicated in the present analysis. Time variations in the occurrence of prolonged periods of geomagnetic calm or of enhanced activity are presented and their relation to solar activity highlighted. It is shown that in the declining phase the occurrence frequencies of Kp = 4–5 (consecutively over 4 intervals can be used as a precursor for the maximum sunspot number to be expected in the next cycle. The semi-annual variation in geomagnetic activity is re-examined utilising not only the Ap index but also the occurrence frequencies of Kp index with different magnitudes. Lack of dependence of the amplitude of semi-annual variation on sunspot number is emphasised. Singular spectrum analysis of the mean monthly Ap index shows some distinct periodic components. The temporal evolution of ~44 month, ~21 month and ~16 month oscillations are examined and it is postulated that while QBO and the 16 month oscillations could be attributed to solar wind and IMF oscillations with analogous periodicity, the 44 month variation is associated with a similar periodicity in recurrent high speed stream caused by sector boundary passage. It is reconfirmed that there could have been only one epoch around 1940 when solar wind speed could have exhibited a 1.3-year periodicity comparable to that seen during the post-1986 period.

  18. Circulation of the polar thermosphere during geomagnetically quiet and active times as observed by Dynamics Explorer 2

    International Nuclear Information System (INIS)

    McCormac, F.G.; Killeen, T.L.; Thayer, J.P.; Hernandez, G.; Tschan, C.R.; Ponthieu, J.J.; Spencer, N.W.

    1987-01-01

    Neutral wind measurements obtained by instruments on board the Dynamics Explorer 2 (DE 2) spacecraft have been used to study the effects of geomagnetic activity on the circulation of the high-latitude neutral thermosphere for solar maximum conditions during the periods of November 1981 through January 1982 and November 1982 through January 1983. The data have been sorted and ordered according to the two geophysical indices Kp and (auroral electrojet) AE. Simple expressions have been derived which describe (1) the maximum antisunward wind speed in the geomagnetic polar cap, (2) the maximum sunward wind speeds in the dawn and dusk sectors of the auroral oval, and (3) the latitudinal extent of the polar cap antisunward neutral wind as functions of Kp and AE. The results show a positive correlation between the geomagnetic indices and the three characteristic features of the neutral circulation described above. Averaged vector wind fields in geomagnetic coordinates for Kp ≤ 2 and Kp ≥ 4 in both northern and southern hemispheres for the 6 months have been derived from the data. In doing this, a first-order invariance of the neutral wind circulation in geomagnetic coordinates as a function of universal time (UT) was assumed. The results show a two-cell circulation pattern in the northern winter hemisphere for both quiet and active geomagnetic periods. The cell sizes increase with increasing geomagnetic activity. The dusk cell is always dominant. The southern summer hemisphere averages show only the dusk circulation cell for both quiet and active geomagnetic periods. The cell sizes increase with increasing geomagnetic activity. The dusk cell is always dominant. The southern summer hemisphere averages show only the dusk circulation cell for both quiet and active geomagnetic periods. A diminution of this cell occurs for reduced levels of geomagnetic activity

  19. Geomagnetic activity forcing of the Northern Annular Mode via the stratosphere

    Directory of Open Access Journals (Sweden)

    D. R. Palamara

    2004-03-01

    Full Text Available We consider various aspects of the link between solar-modulated geomagnetic activity and the Northern Annular Mode (NAM. Our results indicate that the geomagnetic forcing of atmospheric circulation in the Northern Hemisphere is temporally and seasonally restricted, modulated by the Quasi-Biennial Oscillation (QBO, and reliant on stratosphere-troposphere coupling. When the data are restricted to January values after 1965, for years in which the January QBO is eastwards, the correlation coefficient between the geomagnetic AA index and the NAM is 0.85. These results can account for many of the enigmatic features of Northern Hemisphere circulation.

    Key words. Meterology and atmospheric dynamics (general circulation, climatology

  20. VLF Wave Properties During Geomagnetic Storms

    Science.gov (United States)

    Blancarte, J.; Artemyev, A.; Mozer, F.; Agapitov, O. V.

    2017-12-01

    Whistler-mode chorus is important for the global dynamics of the inner magnetosphere electron population due to its ability to scatter and accelerate electrons of a wide energy range in the outer radiation belt. The parameters of these VLF emissions change dynamically during geomagnetic storms. Presented is an analysis of four years of Van Allen probe data, utilizing electric and magnetic field in the VLF range focused on the dynamics of chorus wave properties during the enhancement of geomagnetic activity. It is found that VLF emissions respond to geomagnetic storms in more complicated ways than just by affecting the waves' amplitude growth or depletion. Oblique wave amplitudes grow together with parallel waves during periods of intermediate geomagnetic activity, while the occurrence rate of oblique waves decreases during larger geomagnetic storms.

  1. Evaluation of a new paleosecular variation activity index as a diagnostic tool for geomagnetic field variations

    Science.gov (United States)

    Panovska, Sanja; Constable, Catherine

    2015-04-01

    Geomagnetic indices like Dst, K and A, have been used since the early twentieth century to characterize activity in the external part of the modern geomagnetic field and as a diagnostic for space weather. These indices reflect regional and global activity and serve as a proxy for associated physical processes. However, no such tools are yet available for the internal geomagnetic field driven by the geodynamo in Earth's liquid outer core. To some extent this reflects limited spatial and temporal sampling for longer timescales associated with paleomagnetic secular variation, but recent efforts in both paleomagnetic data gathering and modeling activity suggest that longer term characterization of the internal geomagnetic weather/climate and its variability would be useful. Specifically, we propose an index for activity in paleosecular variation, useful as both a local and global measure of field stability during so-called normal secular variation and as a means of identifying more extreme behavior associated with geomagnetic excursions and reversals. To date, geomagnetic excursions have been identified by virtual geomagnetic poles (VGPs) deviating more than some conventional limit from the geographic pole (often 45 degrees), and/or by periods of significant intensity drops below some critical value, for example 50% of the present-day field. We seek to establish a quantitative definition of excursions in paleomagnetic records by searching for synchronous directional deviations and lows in relative paleointensity. We combine paleointensity variations with deviations from the expected geocentric axial dipole (GAD) inclination in a single parameter, which we call the paleosecular variation (PSV) activity index. This new diagnostic can be used on any geomagnetic time series (individual data records, model predictions, spherical harmonic coefficients, etc.) to characterize the level of paleosecular variation activity, find excursions, or even study incipient reversals

  2. Geomagnetic storms

    International Nuclear Information System (INIS)

    McNamara, A.G.

    1980-01-01

    Disturbances due to geomagnetic storms can affect the functioning of communications satellites and of power lines and other long conductors. Two general classes of geomagnetic activity can be distinguished: ionospheric current flow (the auroral electrojet), and magnetospheric compression. Super magnetic storms, such as the one of August 1972, can occur at any time and average about 17 occurrences per century. Electrical transmission systems can be made more tolerant of such events at a price, but the most effective way to minimize damage is by better operator training coupled with effective early warning systems. (LL)

  3. Solar and Geomagnetic Activity Variations Correlated to Italian M6+ Earthquakes Occurred in 2016

    Science.gov (United States)

    Cataldi, Gabriele; Cataldi, Daniele; Straser, Valentino

    2017-04-01

    Between August 2016 and October 2016 in Italy were recorded three strong earthquakes: M6.2 on August 2016 at 01:36:32 UTC; M6.1 on October 26, 2016 at 19:18:08 UTC and M6,6 on October 30, 2016 at 06:40:18 UTC. The authors of this study wanted to verify the existence of a correlation between these earthquakes and solar/geomagnetic activity. To confirming or not the presence of this kind of correlation, the authors analyzed the conditions of Spaceweather "near Earth" and the characteristics of the Earth's geomagnetic field in the hours that preceded the three earthquakes. The data relating to the three earthquakes were provided by the United States Geological Survey (USGS). The data on ion density used to realize the correlation study are represented by: solar wind ion density variation detected by ACE (Advanced Composition Explorer) Satellite, in orbit near the L1 Lagrange point, at 1.5 million of km from Earth, in direction of the Sun. The instrument used to perform the measurement of the solar wind ion density is the Electron, Proton, and Alpha Monitor (EPAM) instrument, equipped on the ACE Satellite. To conduct the study, the authors have taken in consideration the variation of the solar wind protons density of three different energy fractions: differential proton flux 1060-1900 keV (p/cm^2-sec-ster-MeV); differential proton flux 761-1220 keV (p/cm^2-sec-ster-MeV); differential proton flux 310-580 keV (p/cm^2-sec-ster-MeV). Geomagnetic activity data were provided by Tromsø Geomagnetic Observatory (TGO), Norway; by Scoresbysund Geomagnetic Observatory (SCO), Greenland, Denmark; Dikson Geomagnetic Observatory (DIK), Russia and by Pushkov Institute of terrestrial magnetism, ionosphere and radio wave propagation (IZMIRAN), Troitsk, Moscow Region. The results of the study, in agreement with what already ascertained by authors from 2012, have confirmed that the three strong Italian earthquakes were preceded by a clear increase of the solar wind proton density which

  4. Changes in geomagnetic activity and global temperature during the past 40 years

    Czech Academy of Sciences Publication Activity Database

    Bucha, Václav

    2012-01-01

    Roč. 56, č. 4 (2012), s. 1095-1107 ISSN 0039-3169 Institutional research plan: CEZ:AV0Z30120515 Keywords : geomagnetic activity * polar vortex * climate indices * global temperature Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 0.975, year: 2012

  5. The study of the midlatitude ionospheric response to geomagnetic activity at Nagycenk Geophysical Observatory

    Science.gov (United States)

    Berényi, Kitti; Kis, Árpád; Barta, Veronika; Novák, Attila

    2016-04-01

    Geomagnetic storms affect the ionospheric regions of the terrestrial upper atmosphere, causing several physical and chemical atmospheric processes. The changes and phenomena, which can be seen as a result of these processes, generally called ionospheric storm. These processes depend on altitude, term of the day, and the strength of solar activity, the geomagnetic latitude and longitude. The differences between ionospheric regions mostly come from the variations of altitude dependent neutral and ionized atmospheric components, and from the physical parameters of solar radiation. We examined the data of the ground-based radio wave ionosphere sounding instruments of the European ionospheric stations (mainly the data of Nagycenk Geophysical Observatory), called ionosonde, to determine how and what extent a given strength of a geomagnetic disturbance affect the middle latitude ionospheric regions in winter. We chose the storm for the research from November 2012 and March 2015. As the main result of our research, we can show significant differences between the each ionospheric (F1 and F2) layer parameters on quiet and strong stormy days. When we saw, that the critical frequencies (foF2) increase from their quiet day value, then the effect of the ionospheric storm was positive, otherwise, if they drop, they were negative. With our analysis, the magnitude of these changes could be determined. Furthermore we demonstrated, how a full strong geomagnetic storm affects the ionospheric foF2 parameter during different storm phases. It has been showed, how a positive or negative ionospheric storm develop during a geomagnetic storm. For a more completed analysis, we compared also the evolution of the F2 layer parameters of the European ionosonde stations on a North-South geographic longitude during a full storm duration. Therefore we determined, that the data of the ionosonde at Nagycenk Geophysical Observatory are appropriate, it detects the same state of ionosphere like the

  6. Interplanetary medium and geomagnetic activity after compact flare triplets 1966-1981

    International Nuclear Information System (INIS)

    Ivanov, K.G.; Mikerina, N.V.; Pavlov, P.P.

    1986-01-01

    The interplanetary medium state and geomagnetic activity when the Earth is getting into this or that interplanetary disturbance zone after flare triplets, i.e. trains of three solar flares out of an active zone, are considered. There are the following conditionally differentiated zones in the interplanetary disturbance configuration: a forbidden (F), a perturbed (P) and a normal (N) zones of interplanetary disturbance. The interplanetary medium disturbances and geomagnetic activity after trains of three flares of class 2 and higher out of one of active zones depend on the following factors: the magnetic axis orientation of a bipolar group of active zone spots appeared after flares, time interval between the first and second flares in the train, flare intensity. The conditions of maximum disturbance occurrence pointed out. The interplanetary and geomagnetic disturbance intensity in the N zone is higher than that of the F and P zones (i.e. in the proximity of the great circle planes passing through the flares parallel with tha active zone magnetic axes), and it is higher after quasicompact rather than after compact triplets (i.e. it considerably grows when passing over the critical value of the time interval betwenn the first and second triplet flares, τ 12 =16 h)

  7. Statistical Correlation of Low-Altitude ENA Emissions with Geomagnetic Activity from IMAGE MENA Observations

    Science.gov (United States)

    Mackler, D. A.; Jahn, J.- M.; Perez, J. D.; Pollock, C. J.; Valek, P. W.

    2016-01-01

    Plasma sheet particles transported Earthward during times of active magnetospheric convection can interact with exospheric/thermospheric neutrals through charge exchange. The resulting Energetic Neutral Atoms (ENAs) are free to leave the influence of the magnetosphere and can be remotely detected. ENAs associated with low-altitude (300-800 km) ion precipitation in the high-latitude atmosphere/ionosphere are termed low-altitude emissions (LAEs). Remotely observed LAEs are highly nonisotropic in velocity space such that the pitch angle distribution at the time of charge exchange is near 90deg. The Geomagnetic Emission Cone of LAEs can be mapped spatially, showing where proton energy is deposited during times of varying geomagnetic activity. In this study we present a statistical look at the correlation between LAE flux (intensity and location) and geomagnetic activity. The LAE data are from the MENA imager on the IMAGE satellite over the declining phase of solar cycle 23 (2000-2005). The SYM-H, AE, and Kp indices are used to describe geomagnetic activity. The goal of the study is to evaluate properties of LAEs in ENA images and determine if those images can be used to infer properties of ion precipitation. Results indicate a general positive correlation to LAE flux for all three indices, with the SYM-H showing the greatest sensitivity. The magnetic local time distribution of LAEs is centered about midnight and spreads with increasing activity. The invariant latitude for all indices has a slightly negative correlation. The combined results indicate LAE behavior similar to that of ion precipitation.

  8. Statistical correlation of low-altitude ENA emissions with geomagnetic activity from IMAGE/MENA observations

    Science.gov (United States)

    Mackler, D. A.; Jahn, J.-M.; Perez, J. D.; Pollock, C. J.; Valek, P. W.

    2016-03-01

    Plasma sheet particles transported Earthward during times of active magnetospheric convection can interact with exospheric/thermospheric neutrals through charge exchange. The resulting Energetic Neutral Atoms (ENAs) are free to leave the influence of the magnetosphere and can be remotely detected. ENAs associated with low-altitude (300-800 km) ion precipitation in the high-latitude atmosphere/ionosphere are termed low-altitude emissions (LAEs). Remotely observed LAEs are highly nonisotropic in velocity space such that the pitch angle distribution at the time of charge exchange is near 90°. The Geomagnetic Emission Cone of LAEs can be mapped spatially, showing where proton energy is deposited during times of varying geomagnetic activity. In this study we present a statistical look at the correlation between LAE flux (intensity and location) and geomagnetic activity. The LAE data are from the MENA imager on the IMAGE satellite over the declining phase of solar cycle 23 (2000-2005). The SYM-H, AE, and Kp indices are used to describe geomagnetic activity. The goal of the study is to evaluate properties of LAEs in ENA images and determine if those images can be used to infer properties of ion precipitation. Results indicate a general positive correlation to LAE flux for all three indices, with the SYM-H showing the greatest sensitivity. The magnetic local time distribution of LAEs is centered about midnight and spreads with increasing activity. The invariant latitude for all indices has a slightly negative correlation. The combined results indicate LAE behavior similar to that of ion precipitation.

  9. Evolution of fractality in space plasmas of interest to geomagnetic activity

    Science.gov (United States)

    Muñoz, Víctor; Domínguez, Macarena; Alejandro Valdivia, Juan; Good, Simon; Nigro, Giuseppina; Carbone, Vincenzo

    2018-03-01

    We studied the temporal evolution of fractality for geomagnetic activity, by calculating fractal dimensions from the Dst data and from a magnetohydrodynamic shell model for turbulent magnetized plasma, which may be a useful model to study geomagnetic activity under solar wind forcing. We show that the shell model is able to reproduce the relationship between the fractal dimension and the occurrence of dissipative events, but only in a certain region of viscosity and resistivity values. We also present preliminary results of the application of these ideas to the study of the magnetic field time series in the solar wind during magnetic clouds, which suggest that it is possible, by means of the fractal dimension, to characterize the complexity of the magnetic cloud structure.

  10. On a forecast of geomagnetic activity according to magnetic fields on the Sun

    International Nuclear Information System (INIS)

    Ponyavin, D.I.; Pudovkin, M.I.

    1988-01-01

    Technique for tracking the current layer orientation in the solar corona and solar wind high-velocity flux sources is suggested according to the observation of large-scale magnetic fields at the Sun. Ionospheric magnetic fields in potential approximation are extrapolated to the Sun atmosphere high layers - in the region of probable formation of solar wind and interplanetary magnetic field. The chart of isocline-lines of field vector even inclination to the surface of R=1.8R sun radius sphere is plotted according to the calculated magnetic field. Daily plotting of such charts allows to continuosly track the large-scale structure and evolution of solar wind and interplanetary magnetic field. Th comparison of isoclinic charts with geomagnetic activity for October 1982 has shown the principal possibility to use this technique for the purposes of geomagnetic activity forecasting

  11. Morphology of geomagnetic storms, recorded at Hurbanovo, and its relation to solar activity

    International Nuclear Information System (INIS)

    Ochabova, P.; Psenakova, M.

    1977-01-01

    The morphological structure of geomagnetic storms was investigated using the data on 414 storms, recorded in the years 1949 to 1968 at the Geomagnetic Observatory of Hurbanovo (phi=47.9 deg N, lambda=18.2 deg E). These data also formed a suitable basis for investigating the effect of the solar activity on the characteristic features of storms. The storm-time variation of the geomagnetic field was considered after the Sq-variation had been eliminated. The sets of storms, i.e. 263 storms recorded at a time of high sunspot activity and 151 storms recorded at a time of low activity, were divided into 7 groups, depending on the duration of their initial phase. In 92% of the investigated storms the increase in the horizontal component lasted from 0 to 15 hrs. The effect of the solar activity was markedly reflected in the occurrence of very severe storms, as well as in the maximum decrease in the H-component in the main phase. This can also be seen in the rate at which the storms recover. (author)

  12. Observations of wave activity in the ionosphere over South Africa in geomagnetically quiet and disturbed periods

    Czech Academy of Sciences Publication Activity Database

    Šindelářová, Tereza; Mošna, Zbyšek; Burešová, Dalia; Chum, Jaroslav; McKinnell, L.- A.; Athieno, R.

    2012-01-01

    Roč. 50, č. 2 (2012), s. 182-195 ISSN 0273-1177 R&D Projects: GA ČR(CZ) GAP209/12/2440 Institutional support: RVO:68378289 Keywords : Waves in the ionosphere * HF Doppler type sounding * Geomagnetic activity Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.183, year: 2012 http://www.sciencedirect.com/science/article/pii/S0273117712002591

  13. Strong geomagnetic activity forecast by neural networks under dominant southern orientation of the interplanetary magnetic field

    Czech Academy of Sciences Publication Activity Database

    Valach, F.; Bochníček, Josef; Hejda, Pavel; Revallo, M.

    2014-01-01

    Roč. 53, č. 4 (2014), s. 589-598 ISSN 0273-1177 R&D Projects: GA AV ČR(CZ) IAA300120608; GA MŠk OC09070 Institutional support: RVO:67985530 Keywords : geomagnetic activity * interplanetary magnetic field * artificial neural network * ejection of coronal mass * X-ray flares Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.358, year: 2014

  14. Statistical Characteristics of Solar Wind Dynamic Pressure Enhancements During Geomagnetic Storms

    Directory of Open Access Journals (Sweden)

    C.-R. Choi

    2008-06-01

    Full Text Available Solar wind dynamic pressure enhancements are known to cause various types of disturbances to the magnetosphere. In particular, dynamic pressure enhancements may affect the evolution of magnetic storms when they occur during storm times. In this paper, we have investigated the statistical significance and features of dynamic pressure enhancements during magnetic storm times. For the investigation, we have used a total of 91 geomagnetic storms for 2001-2003, for which the Dst minimum (Dst_min is below -50 nT. Also, we have imposed a set of selection criteria for a pressure enhancement to be considered an event: The main selection criterion is that the pressure increases by ≥50% or ≥3nPa within 30 min and remains to be elevated for 10 min or longer. For our statistical analysis, we define the storm time to be the interval from the main Dst decrease, through Dst_min, to the point where the Dst index recovers by 50%. Our main results are summarized as follows. (i ~81% of the studied storms indicate at least one event of pressure enhancements. When averaged over all the 91 storms, the occurrence rate is 4.5 pressure enhancement events per storm and 0.15 pressure enhancement events per hour. (ii The occurrence rate of the pressure enhancements is about three times higher for CME-driven storm times than for CIR-driven storm times. (iii Only 21.1% of the pressure enhancements show a clear association with an interplanetary shock. (iv A large number of the pressure enhancement events are accompanied with a simultaneous change of IMF By and/or Bz: For example, 73.5% of the pressure enhancement events are associated with an IMF change of either |∆Bz|>2nT or |∆By|>2nT. This last finding suggests that one should consider possible interplay effects between the simultaneous pressure and IMF changes in many situations.

  15. Relation of geomagnetic activity index variations with parameters of interplanetary scintillations

    International Nuclear Information System (INIS)

    Vlasov, V.I.; Shishov, V.I.; Shishova, T.D.

    1985-01-01

    A correlation between the Asub(p)-index of geomagnetic activity, index of interplanetary scintillations and solar wind velocity, has been considered depending on the spatial position of the interplanetary plasma (IPP) regions under study. It is shown, that the scintillation index can be used to forecast the geomagnetic activity, whereas the solar wind velocity can not be used for the purpose. Heliolongitudinal dependence of geoeffectiveness of IPP sreading perturbations agrees well with their structure in the heliolongitudinal cross section (and, on the whole, with the angular structure and direction of IPP perturbation spread). To use interplanetary scintillations in forecasting the geomagnetic activity (on the level of correlation not below 0.5), the angular distance of the investigated IPP regions relative to the Sun-Earth line on the average should not exceed 30-40 deg. The time of delay between the moments of observation of variations in the scintillation index the time of passage of the corresponding heliocentric distances at an average rate of the interplanetary perturbation spread approximately 500 km/s

  16. Relationship between geomagnetic classes’ activity phases and their occurrence during the sunspot cycle

    Directory of Open Access Journals (Sweden)

    Frédéric Ouattara

    2009-06-01

    Full Text Available Four well known geomagnetic classes of activity such as quiet days activity, fluctuating activity, recurrent activity
    and shock activity time occurrences have been determined not only by using time profile of sunspot number
    Rz but also by using aa index values.
    We show that recurrent wind stream activity and fluctuating activity occur in opposite phase and slow solar wind
    activity during minimum phase and shock activity at the maximum phase.
    It emerges from this study that fluctuating activity precedes the sunspot cycle by π/2 and the latter also precedes
    recurrent activity by π/2. Thus in the majority the activities do not happen at random; the sunspot cycle starts
    with quiet days activity, continues with fluctuating activity and during its maximum phase arrives shock activity.
    The descending phase is characterized by the manifestation of recurrent wind stream activity.

  17. The relationship between plasmapause, solar wind and geomagnetic activity between 2007 and 2011

    Energy Technology Data Exchange (ETDEWEB)

    Verbanac, G. [Zagreb Univ. (Croatia). Dept. of Geophysics; Pierrard, V. [Belgian Institute for Space Aeronomy (Space Physics and STCE), Brussels (Belgium); Univ. Catholique de Louvain, Louvain-La-Neuve (Belgium). TECLIM, Earth and Life Inst.; Darrouzet, F. [Belgian Institute for Space Aeronomy (Space Physics and STCE), Brussels (Belgium); Rauch, J.L.; Decreau, P. [Laboratoire de Physique et Chimie de l' Environnement et de l' Espace (LPC2E), Orleans (France); Bandic, M.

    2015-07-01

    Taking advantage of the Cluster satellite mission and especially the observations made by the instrument WHISPER to deduce the electron number density along the orbit of the satellites, we studied the relationships between the plasmapause positions (L{sub PP}) and the following L{sub PP} indicators: (a) solar wind coupling functions B{sub z} (Z component of the interplanetary magnetic field vector, B, in GSM system), BV (related to the interplanetary electric field; B is the magnitude of the interplanetary magnetic field vector, V is solar wind velocity), and dΦ{sub mp}/dt (which combines different physical processes responsible for the magnetospheric activity) and (b) geomagnetic indices Dst, Ap and AE. The analysis is performed separately for three magnetic local time (MLT) sectors (Sector1 - night sector (01:00-07:00MLT); Sector2 - day sector (07:00-16:00MLT); Sector3 - evening sector (16:00-01:00MLT)) and for all MLTs taken together. All L{sub PP} indicators suggest the faster plasmapause response in the postmidnight sector. Delays in the plasmapause responses (hereafter time lags) are approximately 2-27 h, always increasing from Sector1 to Sector3. The obtained fits clearly resolve the MLT structures. The variability in the plasmapause is the largest for low values of L{sub PP} indicators, especially in Sector2. At low activity levels, L{sub PP} exhibits the largest values on the dayside (in Sector2) and the smallest on the postmidnight side (Sector1). Displacements towards larger values on the evening side (Sector3) and towards lower values on the dayside (Sector2) are identified for enhanced magnetic activity. Our results contribute to constraining the physical mechanisms involved in the plasmapause formation and to further study the still not well understood related issues.

  18. The relationship between plasmapause, solar wind and geomagnetic activity between 2007 and 2011

    International Nuclear Information System (INIS)

    Verbanac, G.; Rauch, J.L.; Decreau, P.; Bandic, M.

    2015-01-01

    Taking advantage of the Cluster satellite mission and especially the observations made by the instrument WHISPER to deduce the electron number density along the orbit of the satellites, we studied the relationships between the plasmapause positions (L PP ) and the following L PP indicators: (a) solar wind coupling functions B z (Z component of the interplanetary magnetic field vector, B, in GSM system), BV (related to the interplanetary electric field; B is the magnitude of the interplanetary magnetic field vector, V is solar wind velocity), and dΦ mp /dt (which combines different physical processes responsible for the magnetospheric activity) and (b) geomagnetic indices Dst, Ap and AE. The analysis is performed separately for three magnetic local time (MLT) sectors (Sector1 - night sector (01:00-07:00MLT); Sector2 - day sector (07:00-16:00MLT); Sector3 - evening sector (16:00-01:00MLT)) and for all MLTs taken together. All L PP indicators suggest the faster plasmapause response in the postmidnight sector. Delays in the plasmapause responses (hereafter time lags) are approximately 2-27 h, always increasing from Sector1 to Sector3. The obtained fits clearly resolve the MLT structures. The variability in the plasmapause is the largest for low values of L PP indicators, especially in Sector2. At low activity levels, L PP exhibits the largest values on the dayside (in Sector2) and the smallest on the postmidnight side (Sector1). Displacements towards larger values on the evening side (Sector3) and towards lower values on the dayside (Sector2) are identified for enhanced magnetic activity. Our results contribute to constraining the physical mechanisms involved in the plasmapause formation and to further study the still not well understood related issues.

  19. The relationship between plasmapause, solar wind and geomagnetic activity between 2007 and 2011

    Directory of Open Access Journals (Sweden)

    G. Verbanac

    2015-10-01

    Full Text Available Taking advantage of the Cluster satellite mission and especially the observations made by the instrument WHISPER to deduce the electron number density along the orbit of the satellites, we studied the relationships between the plasmapause positions (LPP and the following LPP indicators: (a solar wind coupling functions Bz (Z component of the interplanetary magnetic field vector, B, in GSM system, BV (related to the interplanetary electric field; B is the magnitude of the interplanetary magnetic field vector, V is solar wind velocity, and dΦmp/dt (which combines different physical processes responsible for the magnetospheric activity and (b geomagnetic indices Dst, Ap and AE. The analysis is performed separately for three magnetic local time (MLT sectors (Sector1 – night sector (01:00–07:00 MLT; Sector2 – day sector (07:00–16:00 MLT; Sector3 – evening sector (16:00–01:00 MLT and for all MLTs taken together. All LPP indicators suggest the faster plasmapause response in the postmidnight sector. Delays in the plasmapause responses (hereafter time lags are approximately 2–27 h, always increasing from Sector1 to Sector3. The obtained fits clearly resolve the MLT structures. The variability in the plasmapause is the largest for low values of LPP indicators, especially in Sector2. At low activity levels,LPP exhibits the largest values on the dayside (in Sector2 and the smallest on the postmidnight side (Sector1. Displacements towards larger values on the evening side (Sector3 and towards lower values on the dayside (Sector2 are identified for enhanced magnetic activity. Our results contribute to constraining the physical mechanisms involved in the plasmapause formation and to further study the still not well understood related issues.

  20. Lower thermosphere (80-100 km) dynamics response to solar and geomagnetic activity: Overview

    International Nuclear Information System (INIS)

    Kazimirovsky, E.S.

    1989-01-01

    The variations of solar and geomagnetic activity may affect the thermosphere circulation via plasma heating and electric fields, especially at high latitudes. The possibility exists that the energy involved in auroral and magnetic storms can produce significant changes of mesosphere and lower thermosphere wind systems. A study of global radar measurements of winds at 80 to 100 km region revealed the short term effects (correlation between wind field and geomagnetic storms) and long term variations over a solar cycle. It seems likely that the correlation results from a modification of planetary waves and tides propagated from below, thus altering the dynamical regime of the thermosphere. Sometimes the long term behavior points rather to a climatic variation with the internal atmospheric cause than to a direct solar control

  1. Analysis of the ULF electromagnetic emission related to seismic activity, Teoloyucan geomagnetic station, 1998-2001

    Directory of Open Access Journals (Sweden)

    A. Kotsarenko

    2004-01-01

    Full Text Available Results of ULF geomagnetic measurements at station Teoloyucan (Central Mexico, 99.11'35.735''W, 19.44'45.100''N, 2280m height in relation to seismic activity in the period 1998-2001 and their analysis are presented. Variations of spectral densities for horizontal and vertical components, polarization densities and spectrograms of magnetic field, their derivatives are analyzed as a part of traditional analysis in this study. Values of spectral density were calculated for 6 fixed frequencies f=1, 3, 10, 30, 100 and 300mHz. Fractal characteristics of spectra were analyzed in the conception of SOC (Self-Organized Criticality. 2 nighttime intervals, 0-3 and 3-6h by local time have been used to decrease the noise interference in row data. In order to exclude the intervals with a high geomagnetic activity from analysis we referred to Ap indices, calculated for corresponding time intervals. The contribution of seismic events to geomagnetic emission was estimated by seismic index ks=100.75Ms/10D, where Ms is the amplitude of the earthquake and D is the distance from its epicenter to the station.

  2. Long-term trends of foF2 independent of geomagnetic activity

    Directory of Open Access Journals (Sweden)

    A. D. Danilov

    Full Text Available A detailed analysis of the foF2 data at a series of ionospheric stations is performed to reveal long-term trends independent of the long-term changes in geomagnetic activity during the recent decades (nongeomagnetic trends. The method developed by the author and published earlier is used. It is found that the results for 21 out of 23 stations considered agree well and give a relative nongeomagnetic trend of -0.0012 per year (or an absolute nongeomagnetic trend of about -0.012 MHz per year for the period between 1958 and the mid-nineties. The trends derived show no dependence on geomagnetic latitude or local time, a fact confirming their independence of geomagnetic activity. The consideration of the earlier period (1948–1985 for a few stations for which the corresponding data are available provides significantly lower foF2 trends, the difference between the later and earlier periods being a factor of 1.6. This is a strong argument in favor of an anthropogenic nature of the trends derived.Key words. Ionosphere (ionosphere-atmosphere interactions; ionospheric disturbances; mid-latitude ionosphere

  3. Geomagnetism and Aeronomy activities in Italy during IGY, 1957/58

    Directory of Open Access Journals (Sweden)

    Lucilla Alfonsi

    2009-06-01

    Full Text Available In 2007 several events were organized to celebrate the fiftieth anniversary of the International Geophysical Year
    (IGY, 1957-1958. The celebrations will last until 2009 and are taking place within different contexts: the International
    Polar Year (IPY, the International Heliophysical Year (IHY, the electronic Geophysical Year (eGY
    and the International Year of Planet Earth (IYPE.
    IGY offered a very appropriate and timely occasion to undertake a series of coordinated observations of various
    geophysical phenomena all over the globe. Italy took part in the broad international effort stimulated by IGY. In
    fact, Italy participated in observations and studies in many of the proposed scientific areas, in particular Geomagnetism
    and Aeronomy. The Istituto Nazionale di Geofisica (ING started the installation of observatories,
    and updated and ensured continuous recording of geophysical observations. Geomagnetism, ionospheric
    physics, seismology, and other geophysical disciplines, were advanced. Although much of the work was undertaken
    in Italy, some attention was also devoted to other areas of the world, in particular Antarctica, where Italy
    participated in seismological observations. This paper gives a summary of the Geomagnetism and Ionospheric
    Physics activities within IGY. Furthermore, we highlight the importance of this historical event and its outcomes
    for the improvement of geophysical observations and the post-IGY growth of scientific investigations in Italy.

  4. Intensity of the Fe XV emission line corona, the level of geomagnetic activity and the velocity of the solar wind

    International Nuclear Information System (INIS)

    Bell, B.; Noci, G.

    1976-01-01

    The average solar wind velocity and the level of geomagnetic activity (Kp) following central meridian passage of coronal weak and bright features identified from Oso 7 isophotograms of Fe XV (284 A) are determined by the method of superposed epochs. Results are consistent with the concept that bright regions possess magnetic field of closed configurations, thereby reducing particle escape, while coronal holes possess open magnetic field lines favorable to particle escape or enhanced outflow of the solar wind. Coronal holes are identified with Bartels' M regions not only statistically but by linking specific long-lived holes with individual sequences of geomagnetic storms. In the study of bright region a subdivision by brightness temperature (T/sub b/) of associated 9.1-cm radiation was found to be significant, with the region s of higher T/sub b/ having a stronger inhibiting power on the outflow of the solar wind when they were located in the solar hemisphere on the same side of the solar equator as the earth. Regions of highest T/sub b/ most strongly depress the outflow of solar wind but are also the most likely to produce flare-associated great storms

  5. Diurnal changes of earthquake activity and geomagnetic Sq-variations

    Directory of Open Access Journals (Sweden)

    G. Duma

    2003-01-01

    Full Text Available Statistic analyses demonstrate that the probability of earthquake occurrence in many earthquake regions strongly depends on the time of day, that is on Local Time (e.g. Conrad, 1909, 1932; Shimshoni, 1971; Duma, 1997; Duma and Vilardo, 1998. This also applies to strong earthquake activity. Moreover, recent observations reveal an involvement of the regular diurnal variations of the Earth’s magnetic field, commonly known as Sq-variations, in this geodynamic process of changing earthquake activity with the time of day (Duma, 1996, 1999. In the article it is attempted to quantify the forces which result from the interaction between the induced Sq-variation currents in the Earth’s lithosphere and the regional Earth’s magnetic field, in order to assess the influence on the tectonic stress field and on seismic activity. A reliable model is obtained, which indicates a high energy involved in this process. The effect of Sq-induction is compared with the results of the large scale electromagnetic experiment "Khibiny" (Velikhov, 1989, where a giant artificial current loop was activated in the Barents Sea.

  6. Unstable Angina Treatment in Various Periods of Geomagnetic Activity

    Science.gov (United States)

    Parshina, S. S.; Tokayeva, L. K.; Afanasiyeva, T. N.; Samsonov, S. N.; Petrova, V. D.; Dolgova, E. M.; Manykina, V. I.; Vodolagina, E. S.

    In 145 patients with unstable angina (UA) there was analized an efficiency of a drug therapy at different types of heliogeophysical activity (HA) during the 23th solar cycle. 83 patients were examined at the period of a lower HA (Kp-index 16,19±0,18), and 62 patients - at the period of a higher HA (Kp-index 17,25±0,21, p<0,05). Baseline severity of patients' condition with UA at the moment of hospitalization at the studied periods did not differ, but the effectiveness of the therapy depended on the period of HA. At the period of a higher HA antianginal effect was stronger than at the lower period of HA (2,27±0,16 points and 1,75±0,12 points, p<0,05), and the need in nitroglycerin on the background of a drug therapy disappeared for 5-7 days quicker than at the period of a lower HA. Maximal hypotensive effect at a higher HA was achieved quicker - on the 3rd day of the treatment, and at a lower HA - only up to hospital discharge (p<0,05). Blood viscosity did not normalize in both of the studied periods, but in small vessels there was noted a decrease of a BV (p<0,05). So, at a higher HA the effectiveness of a drug therapy in patients with UA is higher than at the period of a lower HA.

  7. Geomagnetism 4

    CERN Document Server

    Jacobs, John A

    2013-01-01

    Geomagnetism, Volume 4 focuses on the processes, methodologies, technologies, and approaches involved in geomagnetism, including electric fields, solar wind plasma, pulsations, and gravity waves.The selection first offers information on solar wind, magnetosphere, and the magnetopause of the Earth. Discussions focus on magnetopause structure and transfer processes, magnetosphere electric fields, geomagnetically trapped radiation, microstructure of the solar wind plasma, and hydro magnetic fluctuations and discontinuities. The text then examines geomagnetic tail, neutral upper atmosphere, and ge

  8. Characteristics of seasonal variation and solar activity dependence of the geomagnetic solar quiet daily variation

    Science.gov (United States)

    Shinbori, A.; Koyama, Y.; Nose, M.; Hori, T.

    2017-12-01

    Characteristics of seasonal variation and solar activity dependence of the X- and Y-components of the geomagnetic solar quiet (Sq) daily variation at Memanbetsu in mid-latitudes and Guam near the equator have been investigated using long-term geomagnetic field data with 1-h time resolution from 1957 to 2016. In this analysis, we defined the quiet day when the maximum value of the Kp index is less than 3 for that day. In this analysis, we used the monthly average of the adjusted daily F10.7 corresponding to geomagnetically quiet days. For identification of the monthly mean Sq variation in the X and Y components (Sq-X and Sq-Y), we first determined the baseline of the X and Y components from the average value from 22 to 2 h (LT: local time) for each quiet day. Next, we calculated a deviation from the baseline of the X- and Y-components of the geomagnetic field for each quiet day, and computed the monthly mean value of the deviation for each local time. As a result, Sq-X and Sq-Y shows a clear seasonal variation and solar activity dependence. The amplitude of seasonal variation increases significantly during high solar activities, and is proportional to the solar F10.7 index. The pattern of the seasonal variation is quite different between Sq-X and Sq-Y. The result of the correlation analysis between the solar F10.7 index and Sq-X and Sq-Y shows almost the linear relationship, but the slope and intercept of the linear fitted line varies as function of local time and month. This implies that the sensitivity of Sq-X and Sq-Y to the solar activity is different for different local times and seasons. The local time dependence of the offset value of Sq-Y at Guam and its seasonal variation suggest a magnetic field produced by inter-hemispheric field-aligned currents (FACs). From the sign of the offset value of Sq-Y, it is infer that the inter-hemispheric FACs flow from the summer to winter hemispheres in the dawn and dusk sectors and from the winter to summer hemispheres in

  9. Forecasts of geomagnetic activities and HF radio propagation conditions made at Hiraiso/Japan

    Science.gov (United States)

    Marubashi, K.; Miyamoto, Y.; Kidokoro, T.; Ishii, T.

    1979-01-01

    The Hiraiso Branch of RRL prediction techniques are summarized separately for the 27 day recurrent storm and the flare-associated storm. The storm predictions are compared with the actual geomagnetic activities in two ways. The first one is the comparison on a day to day basis. In the second comparison, the accuracy of the storm predictions during 1965-1976 are evaluated. In addition to the storm prediction, short-term predictions of HF radio propagation conditions are conducted at Hiraiso. The HF propagation predictions are briefly described as an example of the applications of the magnetic storm prediction.

  10. Spectral analysis of the geomagnetic activity index Ap during different IMF conditions (1947-1978)

    International Nuclear Information System (INIS)

    Francia, P.; Villante, U.

    1986-01-01

    The spectral analysis of the geomagnetic activity index Ap (1947-1978) has been conducted for intervals associated respectively with two and four sectors of the interplanetary magnetic fields per solar rotation. A recurrent 2-sector structure is typically associated with an emerging spectral peak close to T s (T s being the period of solar rotation as seen from Earth), while the T 2 /2 modulation becomes more important during intervals corresponding to four sectors per solar rotation. The recurrence tendency of two high-velocity streams per solar rotation seems to reinforce the relative importance of the T 2 /2 modulation

  11. Mesospheric Na Variability and Dependence on Geomagnetic and Solar Activity over Arecibo

    Science.gov (United States)

    Jain, K.; Raizada, S.; Brum, C. G. M.

    2017-12-01

    The Sodium (Na) resonance lidars located at the Arecibo Observatory offer an excellent opportunity to study the mesosphere/lower thermosphere(MLT) region. Different metals like Fe, Mg, Na, K, Ca and their ions are deposited in the 80 - 120 km altitude range due to the ablation of meteors caused by frictional heating during their entry into the Earth's atmosphere. We present an investigation of the neutral mesospheric Na atom layers over Arecibo. Data on the Na concentrations was collected using a resonance lidar tuned to the of Na wavelength at 589 nm. This wavelength is achieved with a dye-laser pumped by the second harmonic (532 nm) generated from a state-of-the-art commercial Nd:YAG laser. The backscattered signal is received on a 0.8 m (diameter) Cassegrain telescope. The study is based on this data acquired from 1998-2017 and its relation to variations in geomagnetic and solar conditions. We also investigate seasonal and long term trends in the data. The nightly-averaged altitude profiles were modeled as Gaussian curves. From this modeled data we obtain parameters such as the peak, abundance, centroid and width of the main Na layer. Preliminary results show that the Na abundance is more sensitive to changes in geomagnetic and solar variations as compared to the width and centroid height. The seasonal variation exhibits higher peak densities during the local summer and has a secondary maximum during the winter [as shown in the attached figure]. Our analysis demonstrates a decrease in the peak and the abundance of Na atoms with the increase of solar and geomagnetic activity.

  12. Transition region of TEC enhancement phenomena during geomagnetically disturbed periods at mid-latitudes

    Directory of Open Access Journals (Sweden)

    K. Unnikrishnan

    2005-12-01

    Full Text Available Large-scale TEC perturbations/enhancements observed during the day sectors of major storm periods, 12-13 February 2000, 23 September 1999, 29 October 2003, and 21 November 2003, were studied using a high resolution GPS network over Japan. TEC enhancements described in the present study have large magnitudes (≥25×1016 electrons/m2 compared to the quiet-time values and long periods (≥120 min. The sequential manner of development and the propagation of these perturbations show that they are initiated at the northern region and propagate towards the southern region of Japan, with velocities >350 m/s. On 12 February 2000, remarkably high values of TEC and background content are observed at the southern region, compared to the north, because of the poleward expansion of the equatorial anomaly crest, which is characterized by strong latitudinal gradients near 35° N (26° N geomagnetically. When the TEC enhancements, initiating at the north, propagate through the region 39-34° N (30-25° N geomagnetically, they undergo transitions characterized by a severe decrease in amplitude of TEC enhancements. This may be due to their interaction with the higher background content of the expanded anomaly crest. However, at the low-latitude region, below 34° N, an increase in TEC is manifested as an enhanced ionization pattern (EIP. This could be due to the prompt penetration of the eastward electric field, which is evident from high values of the southward Interplanetary Magnetic Field component (IMF Bz and AE index. The TEC perturbations observed on the other storm days also exhibit similar transitions, characterized by a decreasing magnitude of the perturbation component, at the region around 39-34° N. In addition to this, on the other storm days, at the low-latitude region, below 34° N, an increase in TEC (EIP feature also indicates the repeatability of the above scenario. It is found that, the latitude and

  13. Transition region of TEC enhancement phenomena during geomagnetically disturbed periods at mid-latitudes

    Directory of Open Access Journals (Sweden)

    K. Unnikrishnan

    2005-12-01

    Full Text Available Large-scale TEC perturbations/enhancements observed during the day sectors of major storm periods, 12-13 February 2000, 23 September 1999, 29 October 2003, and 21 November 2003, were studied using a high resolution GPS network over Japan. TEC enhancements described in the present study have large magnitudes (≥25×1016 electrons/m2 compared to the quiet-time values and long periods (≥120 min. The sequential manner of development and the propagation of these perturbations show that they are initiated at the northern region and propagate towards the southern region of Japan, with velocities >350 m/s. On 12 February 2000, remarkably high values of TEC and background content are observed at the southern region, compared to the north, because of the poleward expansion of the equatorial anomaly crest, which is characterized by strong latitudinal gradients near 35° N (26° N geomagnetically. When the TEC enhancements, initiating at the north, propagate through the region 39-34° N (30-25° N geomagnetically, they undergo transitions characterized by a severe decrease in amplitude of TEC enhancements. This may be due to their interaction with the higher background content of the expanded anomaly crest. However, at the low-latitude region, below 34° N, an increase in TEC is manifested as an enhanced ionization pattern (EIP. This could be due to the prompt penetration of the eastward electric field, which is evident from high values of the southward Interplanetary Magnetic Field component (IMF Bz and AE index. The TEC perturbations observed on the other storm days also exhibit similar transitions, characterized by a decreasing magnitude of the perturbation component, at the region around 39-34° N. In addition to this, on the other storm days, at the low-latitude region, below 34° N, an increase in TEC (EIP feature also indicates the repeatability of the above scenario. It is found that, the latitude and time at which the decrease in magnitude

  14. Reassessment of the thermospheric response to geomagnetic activity at low latitudes

    International Nuclear Information System (INIS)

    Berger, C.; Barlier, F.; Ill, M.

    1988-01-01

    The present study takes advantage of measurements made at low latitudes by the Cactus accelerometer. From such measurements the response of several thermospheric parameters to geomagnetic activity can be simultaneously and reliably retrieved: total density, density scale height, vertical density scale height gradient, temperature, O/N 2 ratio and mean molecular mass. On investigation their behaviour exhibits a diurnal variation, some features of which have not been described, especially in the case of strong geomagnetic storms. In particular, the night scale height response appears to be stronger than the day one while its vertical gradients increase by day and slightly decrease at night. The temperature increase is higher by day while the O/N 2 ratio decreases by day, and increases at night at constant pressure level as well as at fixed height. By day, significant vertical temperature gradients are also found. These results as well as others are analysed in the light of existing theories and compared to the predictions of existing thermospheric models. Strong meridional winds at night, heat transport through thermal conductivity as well as wave dissipation during the day might be factors helping to account for such a behaviour

  15. Satellite Geomagnetism

    DEFF Research Database (Denmark)

    Olsen, Nils; Stolle, Claudia

    2012-01-01

    Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade....... The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite constellation Swarm will ensure continuity of such measurement and provide enhanced possibilities to improve our...... ability to characterize and understand the many sources that contribute to Earth’s magnetic field. In this review, we summarize investigations of Earth’s interior and environment that have been possible through the analysis of high-precision magnetic field observations taken by LEO satellites....

  16. Long-term rise in geomagnetic activity - A close connection between quiet days and storms

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne

    2000-01-01

    Geomagnetic quiet days and magnetic storms are naturally believed to be due to very different solar wind conditions. In this study we however demonstrate that the long-term variation of geomagnetic quiet and disturbed days are surprisingly similar. By the use of daily averages of the geomagnetic.......7. The results indicate that the longterm,increase is due to an increase in the background solar wind parameters, rather than in the number of solar wind disturbances....

  17. Seasonal Dependence of Geomagnetic Active-Time Northern High-Latitude Upper Thermospheric Winds

    Science.gov (United States)

    Dhadly, Manbharat S.; Emmert, John T.; Drob, Douglas P.; Conde, Mark G.; Doornbos, Eelco; Shepherd, Gordon G.; Makela, Jonathan J.; Wu, Qian; Nieciejewski, Richard J.; Ridley, Aaron J.

    2018-01-01

    This study is focused on improving the poorly understood seasonal dependence of northern high-latitude F region thermospheric winds under active geomagnetic conditions. The gaps in our understanding of the dynamic high-latitude thermosphere are largely due to the sparseness of thermospheric wind measurements. With current observational facilities, it is infeasible to construct a synoptic picture of thermospheric winds, but enough data with wide spatial and temporal coverage have accumulated to construct a meaningful statistical analysis. We use long-term data from eight ground-based and two space-based instruments to derive climatological wind patterns as a function of magnetic local time, magnetic latitude, and season. These diverse data sets possess different geometries and different spatial and solar activity coverage. The major challenge is to combine these disparate data sets into a coherent picture while overcoming the sampling limitations and biases among them. In our previous study (focused on quiet time winds), we found bias in the Gravity Field and Steady State Ocean Circulation Explorer (GOCE) cross-track winds. Here we empirically quantify the GOCE bias and use it as a correction profile for removing apparent bias before empirical wind formulation. The assimilated wind patterns exhibit all major characteristics of high-latitude neutral circulation. The latitudinal extent of duskside circulation expands almost 10∘ from winter to summer. The dawnside circulation subsides from winter to summer. Disturbance winds derived from geomagnetic active and quiet winds show strong seasonal and latitudinal variability. Comparisons between wind patterns derived here and Disturbance Wind Model (DWM07) (which have no seasonal dependence) suggest that DWM07 is skewed toward summertime conditions.

  18. Detailed characteristics of radiation belt electrons revealed by CSSWE/REPTile measurements: Geomagnetic activity response and precipitation observation

    Science.gov (United States)

    Zhang, K.; Li, X.; Schiller, Q.; Gerhardt, D.; Zhao, H.; Millan, R.

    2017-08-01

    Earth's outer radiation belt electrons are highly dynamic. We study the detailed characteristics of relativistic electrons in the outer belt using measurements from the Colorado Student Space Weather Experiment (CSSWE) mission, a low Earth orbit (LEO) CubeSat, which traverses the radiation belt four times in one orbit ( 1.5 h) and has the advantage of measuring the dynamic activities of the electrons including their rapid precipitation. We focus on the measured electron response to geomagnetic activity for different energies to show that there are abundant sub-MeV electrons in the inner belt and slot region. These electrons are further enhanced during active times, while there is a lack of >1.63 MeV electrons in these regions. We also show that the variation of measured electron flux at LEO is strongly dependent on the local magnetic field strength, which is far from a dipole approximation. Moreover, a specific precipitation band, which happened on 19 January 2013, is investigated based on the conjunctive measurement of CSSWE, the Balloon Array for Radiation belt Relativistic Electron Losses, and one of the Polar Operational Environmental Satellites. In this precipitation band event, the net loss of the 0.58-1.63 MeV electrons (L = 3.5-6) is estimated to account for 6.8% of the total electron content.

  19. The association between phenomena on the Sun, geomagnetic activity, meteorological variables, and cardiovascular characteristic of patients with myocardial infarction

    Science.gov (United States)

    Vencloviene, Jone; Babarskiene, Ruta; Slapikas, Rimvydas; Sakalyte, Gintare

    2013-09-01

    It has been found that solar and geomagnetic activity affects the cardiovascular system. Some evidence has been reported on the increase in the rate of myocardial infarction, stroke and myocardial infarction related deaths during geomagnetic storms. We investigated the association between cardiovascular characteristics of patients, admitted for myocardial infarction with ST elevation (STEMI), and geomagnetic activity (GMA), solar proton events (SPE), solar flares, and meteorological variables during admission. The data of 1,979 patients hospitalized at the Hospital of Lithuanian University of Health Sciences (Kaunas) were analyzed. We evaluated the association between environmental variables and patient's characteristics by multivariate logistic regression, controlling patient's gender and age. Two days after geomagnetic storms the risk of STEMI was over 1.5 times increased in patients who had a medical history of myocardial infarction, stable angina, renal or pulmonary diseases. The dose-response association between GMA level and STEMI risk for patients with renal diseases in history was observed. Two days after SPE the risk of STEMI in patients with stable angina in anamnesis was increased over 1.5 times, adjusting by GMA level. The SPE were associated with an increase of risk for patients with renal diseases in history. This study confirms the strongest effect of phenomena in the Sun in high risk patients.

  20. MAXIMUM CORONAL MASS EJECTION SPEED AS AN INDICATOR OF SOLAR AND GEOMAGNETIC ACTIVITIES

    International Nuclear Information System (INIS)

    Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Gopalswamy, N.; Ozguc, A.; Rozelot, J. P.

    2011-01-01

    We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23). Our new findings are as follows. (1) There is a noteworthy relationship between monthly averaged maximum CME speeds and sunspot numbers, Ap and Dst indices. Various peculiarities in the monthly Dst index are correlated better with the fine structures in the CME speed profile than that in the ISSN data. (2) Unlike the sunspot numbers, the CME speed index does not exhibit a double peak maximum. Instead, the CME speed profile peaks during the declining phase of solar cycle 23. Similar to the Ap index, both CME speed and the Dst indices lag behind the sunspot numbers by several months. (3) The CME number shows a double peak similar to that seen in the sunspot numbers. The CME occurrence rate remained very high even near the minimum of the solar cycle 23, when both the sunspot number and the CME average maximum speed were reaching their minimum values. (4) A well-defined peak of the Ap index between 2002 May and 2004 August was co-temporal with the excess of the mid-latitude coronal holes during solar cycle 23. The above findings suggest that the CME speed index may be a useful indicator of both solar and geomagnetic activities. It may have advantages over the sunspot numbers, because it better reflects the intensity of Earth-directed solar eruptions.

  1. Latitudinal variation rate of geomagnetic cutoff rigidity in the active Chilean convergent margin

    Science.gov (United States)

    Cordaro, Enrique G.; Venegas, Patricio; Laroze, David

    2018-03-01

    We present a different view of secular variation of the Earth's magnetic field, through the variations in the threshold rigidity known as the variation rate of geomagnetic cutoff rigidity (VRc). As the geomagnetic cutoff rigidity (Rc) lets us differentiate between charged particle trajectories arriving at the Earth and the Earth's magnetic field, we used the VRc to look for internal variations in the latter, close to the 70° south meridian. Due to the fact that the empirical data of total magnetic field BF and vertical magnetic field Bz obtained at Putre (OP) and Los Cerrillos (OLC) stations are consistent with the displacement of the South Atlantic magnetic anomaly (SAMA), we detected that the VRc does not fully correlate to SAMA in central Chile. Besides, the lower section of VRc seems to correlate perfectly with important geological features, like the flat slab in the active Chilean convergent margin. Based on this, we next focused our attention on the empirical variations of the vertical component of the magnetic field Bz, recorded in OP prior to the Maule earthquake in 2010, which occurred in the middle of the Chilean flat slab. We found a jump in Bz values and main frequencies from 3.510 to 5.860 µHz, in the second derivative of Bz, which corresponds to similar magnetic behavior found by other research groups, but at lower frequency ranges. Then, we extended this analysis to other relevant subduction seismic events, like Sumatra in 2004 and Tohoku in 2011, using data from the Guam station. Similar records and the main frequencies before each event were found. Thus, these results seem to show that magnetic anomalies recorded on different timescales, as VRc (decades) and Bz (days), may correlate with some geological events, as the lithosphere-atmosphere-ionosphere coupling (LAIC).

  2. On the role of solar and geomagnetic activity in long-term trends in the atmosphere-ionosphere system

    Czech Academy of Sciences Publication Activity Database

    Laštovička, Jan

    2005-01-01

    Roč. 67, č. 1-2 (2005), s. 83-92 ISSN 1364-6826 R&D Projects: GA AV ČR KSK3012103; GA AV ČR IAA3042102 Institutional research plan: CEZ:AV0Z30420517 Keywords : Long-term trends * Atmosphere * Ionosphere * Solar activity * Geomagnetic activity Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.309, year: 2005

  3. Quasi-two-year cycle in indices of geomagnetic and solar activity

    International Nuclear Information System (INIS)

    Nuzhdina, M.A.

    1986-01-01

    The spectral, amplitude and phase analysis of monthly standardized anomalies in the indices of planetary geomagnetic disturbance and Wolf numbers for the 100-year period and 18-year time ranges are carried out. There is a weak correlation between the monthly anomalies of fluctuations of the Wolf numbers and planetary indices of geomagnetic distubance manifesting quasi-two-year cyclic recurrence. There is the quasi-two-year cycle of 26 months average duration in the indices of geomagnetic disturbance and Wolf numbers. The quasi-two-year cycle is a rather wide band with the oscillation periods of 21 to 29 months having different amplitudes and phases. The quasi-two-year cycle in geomagnetism and the Wolf numbers is unstable: for 100 years of observations its components change in amplitude and phase

  4. Long-term geomagnetic changes observed in association with earthquake swarm activities in the Izu Peninsula, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Oshiman, N. [Kyoto University Kyoto (Japan). Disaster Prevention Research Institute; Sasai, Y.; Ishikawa, Y.; Koyama, S. [Tokyo Univ., Tokyo (Japan). Earthquake Research Institute; Honkura, Y. [Tokyo Univ., Tokyo (Japan). Dept. of Earth and Planetary Sciences

    2001-04-01

    Anomalous crustal uplift has continued since 1976 in the Izu Peninsula, Japan. Earthquake swarms have also occurred intermittently off the coast of Ito since 1978. Observations of the total intensity of the geomagnetic field in the peninsula started in 1976 to detect anomalous changes in association with those crustal activities. In particular, a dense continuous observation network using proton magnetometers was established in the northeastern part of the peninsula, immediately after the sea-floor eruption off the coast of Ito in 1989. No remarkable swarm activities were observed there from 1990 to 1992. However, after the occurrence of a small swarm in January 1993, five large swarm activities were observed. At some observation sites, it was observed a remarkable long-term trend in the total geomagnetic field in association with the change in the distribution pattern in the seismicity of the earthquake swarms.

  5. Linear filters as a method of real-time prediction of geomagnetic activity

    International Nuclear Information System (INIS)

    McPherron, R.L.; Baker, D.N.; Bargatze, L.F.

    1985-01-01

    Important factors controlling geomagnetic activity include the solar wind velocity, the strength of the interplanetary magnetic field (IMF), and the field orientation. Because these quantities change so much in transit through the solar wind, real-time monitoring immediately upstream of the earth provides the best input for any technique of real-time prediction. One such technique is linear prediction filtering which utilizes past histories of the input and output of a linear system to create a time-invariant filter characterizing the system. Problems of nonlinearity or temporal changes of the system can be handled by appropriate choice of input parameters and piecewise approximation in various ranges of the input. We have created prediction filters for all the standard magnetic indices and tested their efficiency. The filters show that the initial response of the magnetosphere to a southward turning of the IMF peaks in 20 minutes and then again in 55 minutes. After a northward turning, auroral zone indices and the midlatitude ASYM index return to background within 2 hours, while Dst decays exponentially with a time constant of about 8 hours. This paper describes a simple, real-time system utilizing these filters which could predict a substantial fraction of the variation in magnetic activity indices 20 to 50 minutes in advance

  6. ULF geomagnetic activity effects on tropospheric temperature, specific humidity, and cloud cover in Antarctica, during 2003-2010

    Science.gov (United States)

    Regi, Mauro; Redaelli, Gianluca; Francia, Patrizia; De Lauretis, Marcello

    2017-06-01

    In the present study we investigated the possible relationship between the ULF geomagnetic activity and the variations of several atmospheric parameters. In particular, we compared the ULF activity in the Pc1-2 frequency band (100 mHz-5 Hz), computed from geomagnetic field measurements at Terra Nova Bay in Antarctica, with the tropospheric temperature T, specific humidity Q, and cloud cover (high cloud cover, medium cloud cover, and low cloud cover) obtained from reanalysis data set. The statistical analysis was conducted during the years 2003-2010, using correlation and Superposed Epoch Analysis approaches. The results show that the atmospheric parameters significantly change following the increase of geomagnetic activity within 2 days. These changes are evident in particular when the interplanetary magnetic field Bz component is oriented southward (Bz0). We suggest that both the precipitation of electrons induced by Pc1-2 activity and the intensification of the polar cap potential difference, modulating the microphysical processes in the clouds, can affect the atmosphere conditions.

  7. Reconstruction of geomagnetic activity and near-Earth interplanetary conditions over the past 167 yr - Part 1: A new geomagnetic data composite

    Science.gov (United States)

    Lockwood, M.; Barnard, L.; Nevanlinna, H.; Owens, M. J.; Harrison, R. G.; Rouillard, A. P.; Davis, C. J.

    2013-11-01

    We present a new composite of geomagnetic activity which is designed to be as homogeneous in its construction as possible. This is done by only combining data that, by virtue of the locations of the source observatories used, have similar responses to solar wind and IMF (interplanetary magnetic field) variations. This will enable us (in Part 2, Lockwood et al., 2013a) to use the new index to reconstruct the interplanetary magnetic field, B, back to 1846 with a full analysis of errors. Allowance is made for the effects of secular change in the geomagnetic field. The composite uses interdiurnal variation data from Helsinki for 1845-1890 (inclusive) and 1893-1896 and from Eskdalemuir from 1911 to the present. The gaps are filled using data from the Potsdam (1891-1892 and 1897-1907) and the nearby Seddin observatories (1908-1910) and intercalibration achieved using the Potsdam-Seddin sequence. The new index is termed IDV(1d) because it employs many of the principles of the IDV index derived by Svalgaard and Cliver (2010), inspired by the u index of Bartels (1932); however, we revert to using one-day (1d) means, as employed by Bartels, because the use of near-midnight values in IDV introduces contamination by the substorm current wedge auroral electrojet, giving noise and a dependence on solar wind speed that varies with latitude. The composite is compared with independent, early data from European-sector stations, Greenwich, St Petersburg, Parc St Maur, and Ekaterinburg, as well as the composite u index, compiled from 2-6 stations by Bartels, and the IDV index of Svalgaard and Cliver. Agreement is found to be extremely good in all cases, except two. Firstly, the Greenwich data are shown to have gradually degraded in quality until new instrumentation was installed in 1915. Secondly, we infer that the Bartels u index is increasingly unreliable before about 1886 and overestimates the solar cycle amplitude between 1872 and 1883 and this is amplified in the proxy data used

  8. Reconstruction of geomagnetic activity and near-Earth interplanetary conditions over the past 167 yr – Part 1: A new geomagnetic data composite

    Directory of Open Access Journals (Sweden)

    M. Lockwood

    2013-11-01

    Full Text Available We present a new composite of geomagnetic activity which is designed to be as homogeneous in its construction as possible. This is done by only combining data that, by virtue of the locations of the source observatories used, have similar responses to solar wind and IMF (interplanetary magnetic field variations. This will enable us (in Part 2, Lockwood et al., 2013a to use the new index to reconstruct the interplanetary magnetic field, B, back to 1846 with a full analysis of errors. Allowance is made for the effects of secular change in the geomagnetic field. The composite uses interdiurnal variation data from Helsinki for 1845–1890 (inclusive and 1893–1896 and from Eskdalemuir from 1911 to the present. The gaps are filled using data from the Potsdam (1891–1892 and 1897–1907 and the nearby Seddin observatories (1908–1910 and intercalibration achieved using the Potsdam–Seddin sequence. The new index is termed IDV(1d because it employs many of the principles of the IDV index derived by Svalgaard and Cliver (2010, inspired by the u index of Bartels (1932; however, we revert to using one-day (1d means, as employed by Bartels, because the use of near-midnight values in IDV introduces contamination by the substorm current wedge auroral electrojet, giving noise and a dependence on solar wind speed that varies with latitude. The composite is compared with independent, early data from European-sector stations, Greenwich, St Petersburg, Parc St Maur, and Ekaterinburg, as well as the composite u index, compiled from 2–6 stations by Bartels, and the IDV index of Svalgaard and Cliver. Agreement is found to be extremely good in all cases, except two. Firstly, the Greenwich data are shown to have gradually degraded in quality until new instrumentation was installed in 1915. Secondly, we infer that the Bartels u index is increasingly unreliable before about 1886 and overestimates the solar cycle amplitude between 1872 and 1883 and this is

  9. Resistance to Hydrogen Peroxide Highlights Gymnodinium catenatum (Dinophyceae) Sensitivity to Geomagnetic Activity.

    Science.gov (United States)

    Vale, Paulo

    2018-01-01

    The chain-forming dinoflagellate Gymnodinium catenatum was exposed to hydrogen peroxide. Microscopical examination revealed striking dose-response alterations in chain formation above 245 μm: singlets replaced the dominance of long chain formations. These observations were valid for cells acclimated to halogen light. Under fluorescent light, cells were more resistant to modifications in chain length after H 2 O 2 exposure. Growth along 9 h in the presence of extracellular H 2 O 2 followed an hormesis response in both light regimes. Under halogen light conditions, alterations in chain formation and net growth were related to culture time, inocula concentration and geomagnetic activity (GMA) in the proceeding hours. Below a 16 nT threshold in GMA average growth was 0%, while above 16 nT it was circa +9%, independently if the local static magnetic field was altered by a permanent magnet or not. Mycosporine-like amino acids that can have an antioxidant role and are easily oxidized decreased from 7.1 to 6.5 pg cell -1 (P < 0.05) under halogen light and exposure to 245 μm H 2 O 2 . GMA, as well as UV-A, increased stress responsiveness that can momentarily protect cells from extracellular H 2 O 2 addition. However, stress response is dependent on bio-availability of several micronutrients and macronutrients, many found at limiting concentrations in oceanic waters. © 2017 The American Society of Photobiology.

  10. Influence of solar and geomagnetic activity in Gymnodinium catenatum (Dinophyceae) cultures.

    Science.gov (United States)

    Vale, Paulo

    2017-01-01

    Laboratory cultures of the paralytic shellfish poisoning producing microalga Gymnodinium catenatum were subjected to a hypo-osmotic shock and changes in cell concentration were observed in two separate experiments of 8 and 24 hours duration, respectively. The increase in geomagnetic activity (GMA), radio and X-ray fluxes and solar X-ray flares were negatively correlated with cell numbers. Cell losses were observed in the short experiment, but not in the longest one. GMA action was related to the course of the experimental period, while electromagnetic radiation (EMR) was only significantly related when the previous hours before the experiments were considered. The differential action windows might be indicative of two differential disruptive mechanisms: EMR might act on DNA synthesis and mitosis phases of the cell cycle (taking place in the dark period) and GMA might be more disruptive at the end of mytosis or cytokinesis phases taking place in the light period. Formation of long chains (> 4 cells/chain) was reduced with salinity and with temperatures above 27ºC but increased with EMR and GMA, particularly when grown at the highest temperatures recorded during the study period (≥28ºC).

  11. Analysis of the geomagnetic activity of the Dst index and self-affine fractals using wavelet transforms

    Directory of Open Access Journals (Sweden)

    H. L. Wei

    2004-01-01

    Full Text Available The geomagnetic activity of the Dst index is analyzed using wavelet transforms and it is shown that the Dst index possesses properties associated with self-affine fractals. For example, the power spectral density obeys a power-law dependence on frequency, and therefore the Dst index can be viewed as a self-affine fractal dynamic process. In fact, the behaviour of the Dst index, with a Hurst exponent H≈0.5 (power-law exponent β≈2 at high frequency, is similar to that of Brownian motion. Therefore, the dynamical invariants of the Dst index may be described by a potential Brownian motion model. Characterization of the geomagnetic activity has been studied by analysing the geomagnetic field using a wavelet covariance technique. The wavelet covariance exponent provides a direct effective measure of the strength of persistence of the Dst index. One of the advantages of wavelet analysis is that many inherent problems encountered in Fourier transform methods, such as windowing and detrending, are not necessary.

  12. The Distribution of Chorus and Plasmaspheric Hiss Waves in the Inner Magnetospahere as Functions of Geomagnetic Activity and Solar Wind Parameters as Observed by The Van Allen Probes.

    Science.gov (United States)

    Aryan, H.; Sibeck, D. G.; Balikhin, M. A.; Agapitov, O. V.; Kletzing, C.

    2015-12-01

    The dynamics of the radiation belts is dependent upon the acceleration and loss of radiation belt electrons that is largely determined by the interaction of georesonant wave particles with chorus and plasmaspheric hiss waves. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity as expressed by the geomagnetic indices (Ae, Kp, and Dst). However, it has been shown that not all geomagnetic storms necessarily increase the flux of energetic electrons at the radiation belts. In fact, almost 20% of all geomagnetic storms cause a decrease in the flux of energetic electrons, while 30% has relatively no effect. Also, the geomagnetic indices are indirect, nonspecific parameters compiled from imperfectly covered ground based measurements that lack time history. This emphasises the need to present wave distributions as a function of both geomagnetic activity and solar wind parameters, such as velocity (V), density (n), and interplanetary magnetic field component (Bz), that are known to be predominantly effective in the control of radiation belt energetic electron fluxes. This study presents the distribution of chorus and plasmaspheric hiss waves in the inner magnetosphere as functions of both geomagnetic activity and solar wind parameters for different L-shell, magnetic local time, and magnetic latitude. This study uses almost three years of data measured by the EMFISIS on board the Van Allen Probes. Initial results indicate that the intensity of chorus and plasmaspheric hiss emissions are not only dependent on the geomagnetic activity but also dependent on solar wind parameters. The largest average wave intensities are observed with equatorial chorus in the region 4active conditions, fast solar wind velocity, low solar wind density, and highly negative Bz respectively.

  13. Pitch angle distributions of electrons at dipolarization sites during geomagnetic activity: THEMIS observations

    Science.gov (United States)

    Wang, Kaiti; Lin, Ching-Huei; Wang, Lu-Yin; Hada, Tohru; Nishimura, Yukitoshi; Turner, Drew L.; Angelopoulos, Vassilis

    2014-12-01

    Changes in pitch angle distributions of electrons with energies from a few eV to 1 MeV at dipolarization sites in Earth's magnetotail are investigated statistically to determine the extent to which adiabatic acceleration may contribute to these changes. Forty-two dipolarization events from 2008 and 2009 observed by Time History of Events and Macroscale Interactions during Substorms probes covering the inner plasma sheet from 8 RE to 12 RE during geomagnetic activity identified by the AL index are analyzed. The number of observed events with cigar-type distributions (peaks at 0° and 180°) decreases sharply below 1 keV after dipolarization because in many of these events, electron distributions became more isotropized. From above 1 keV to a few tens of keV, however, the observed number of cigar-type events increases after dipolarization and the number of isotropic events decreases. These changes can be related to the ineffectiveness of Fermi acceleration below 1 keV (at those energies, dipolarization time becomes comparable to electron bounce time). Model-calculated pitch angle distributions after dipolarization with the effect of betatron and Fermi acceleration tested indicate that these adiabatic acceleration mechanisms can explain the observed patterns of event number changes over a large range of energies for cigar events and isotropic events. Other factors still need to be considered to assess the observed increase in cigar events around 2 keV. Indeed, preferential directional increase/loss of electron fluxes, which may contribute to the formation of cigar events, was observed. Nonadiabatic processes to accelerate electrons in a parallel direction may also be important for future study.

  14. Did Geomagnetic Activity Challenge Electric Power Reliability During Solar Cycle 23? Evidence from the PJM Regional Transmission Organization in North America

    Science.gov (United States)

    Forbes, Kevin F.; Cyr, Chris St

    2012-01-01

    During solar cycle 22, a very intense geomagnetic storm on 13 March 1989 contributed to the collapse of the Hydro-Quebec power system in Canada. This event clearly demonstrated that geomagnetic storms have the potential to lead to blackouts. This paper addresses whether geomagnetic activity challenged power system reliability during solar cycle 23. Operations by PJM Interconnection, LLC (hereafter PJM), a regional transmission organization in North America, are examined over the period 1 April 2002 through 30 April 2004. During this time PJM coordinated the movement of wholesale electricity in all or parts of Delaware, Maryland, New Jersey, Ohio, Pennsylvania, Virginia, West Virginia, and the District of Columbia in the United States. We examine the relationship between a proxy of geomagnetically induced currents (GICs) and a metric of challenged reliability. In this study, GICs are proxied using magnetometer data from a geomagnetic observatory located just outside the PJM control area. The metric of challenged reliability is the incidence of out-of-economic-merit order dispatching due to adverse reactive power conditions. The statistical methods employed make it possible to disentangle the effects of GICs on power system operations from purely terrestrial factors. The results of the analysis indicate that geomagnetic activity can significantly increase the likelihood that the system operator will dispatch generating units based on system stability considerations rather than economic merit.

  15. On a relation of geomagnetic activity, solar wind velocity and irregularity of daily rotation of the Earth

    International Nuclear Information System (INIS)

    Kalinin, Yu.D.; Kiselev, V.M.

    1980-01-01

    A possibility of the presence of statistic relation between the changes of the Earth rotation regime and the mean velocity of solar wind is discussed. The ratio between the solar wind velocity observed and planetary index of geomagnetic activity am is used to determine the annual average values of solar wind velocity beyond the twentieth cycle of solar activity. The restored changes of solar wind velocity are compared with solar conditioned variations of the Earth day duration and it is shown that the correspondence takes place only at frequencies lower the frequency of 11-year cycle [ru

  16. The effect of solar-geomagnetic activity during and after admission on survival in patients with acute coronary syndromes

    Science.gov (United States)

    Vencloviene, Jone; Babarskiene, Ruta; Milvidaite, Irena; Kubilius, Raimondas; Stasionyte, Jolanta

    2014-08-01

    A number of studies have established the effects of solar-geomagnetic activity on the human cardio-vascular system. It is plausible that the heliophysical conditions existing during and after hospital admission may affect survival in patients with acute coronary syndromes (ACS). We analyzed data from 1,413 ACS patients who were admitted to the Hospital of Kaunas University of Medicine, Lithuania, and who survived for more than 4 days. We evaluated the associations between active-stormy geomagnetic activity (GMA), solar proton events (SPE), and solar flares (SF) that occurred 0-3 days before and after admission, and 2-year survival, based on Cox's proportional-hazards model, controlling for clinical data. After adjustment for clinical variables, active-stormy GMA on the 2nd day after admission was associated with an increased (by 1.58 times) hazard ratio (HR) of cardiovascular death (HR = 1.58, 95 % CI 1.07-2.32). For women, geomagnetic storm (GS) 2 days after SPE occurred 1 day after admission increased the HR by 3.91 times (HR = 3.91, 95 % CI 1.31-11.7); active-stormy GMA during the 2nd-3rd day after admission increased the HR by over 2.5 times (HR = 2.66, 95 % CI 1.40-5.03). In patients aged over 70 years, GS occurring 1 day before or 2 days after admission, increased the HR by 2.5 times, compared to quiet days; GS in conjunction with SF on the previous day, nearly tripled the HR (HR = 3.08, 95 % CI 1.32-7.20). These findings suggest that the heliophysical conditions before or after the admission affect the hazard ratio of lethal outcome; adjusting for clinical variables, these effects were stronger for women and older patients.

  17. Geomagnetic anomalies - possible earthquake precursors - linked with 2004 significant seismic activity in Vrancea, Romania

    International Nuclear Information System (INIS)

    Enescu, D.

    2005-01-01

    The association between a precursory geomagnetic anomaly and a Vrancea earthquake of moderate-to-high magnitude (M W = 6.3) followed by weaker earthquakes (M W W ≤ 6.3 the conclusion of our earlier papers, i.e., that the great majority of Vrancea earthquakes of magnitudes 3.7 ≤ M W ≤5.0 were accompanied by observable precursory electromagnetic anomalies. Our works show that neither the precursor time nor the amplitude of the precursory magnetic anomaly can be linked reliably with the magnitude of the anticipated earthquake. Knowing the way electric resistivity varies ahead of an earthquake, we can assert that the earthquake-precursory growth in geomagnetic impedance is matched by an earthquake-precursory decrease of electric resistivity. (authors)

  18. Longitudinal distribution of recurrent solar activity sources and its reflection in geomagnetic variations

    International Nuclear Information System (INIS)

    Letfus, V.; Apostolov, E.M.

    1980-01-01

    By analysing the autocorrelation function of the geomagnetic Asup(p)-index, a series of subsidiary maxima were found which seem to indicate that they correspond to periods considerably different from the solar rotation period. It was found that these subsidiary maxima are located symmetrically around the maxima of the first and second recurrences of the solar rotation period (and probably also around the subsequent ones). This fact leads to a model of two or more geoactive longitudes on the Sun. (author)

  19. Quasi-periodic fractal patterns in geomagnetic reversals, geological activity, and astronomical events

    International Nuclear Information System (INIS)

    Puetz, Stephen J.; Borchardt, Glenn

    2015-01-01

    Highlights: • Spectral analysis indicates similar harmonics in astronomical and geological events. • Quasi-periodic cycles occur in tripling patterns of 30.44, 91.33, 274, 822, and 2466 myr. • Similar astro- and geo-phases suggest that the cycles develop from a common source. - Abstract: The cause of geomagnetic reversals remains a geological mystery. With the availability of improved paleomagnetic databases in the past three years, a reexamination of possible periodicity in the geomagnetic reversal rate seems warranted. Previous reports of cyclicity in the reversal rate, along with the recent discovery of harmonic cycles in a variety of natural events, sparked our interest in reevaluating possible patterns in the reversal rate. Here, we focus on geomagnetic periodicity, but also analyze paleointensity, zircon formation, star formation, quasar formation, supernova, and gamma ray burst records to determine if patterns that occur in other types of data have similar periodicity. If so, then the degree of synchronization will indicate likely causal relationships with geomagnetic reversals. To achieve that goal, newly available time-series records from these disciplines were tested for cyclicity by using spectral analysis and time-lagged cross-correlation techniques. The results showed evidence of period-tripled cycles of 30.44, 91.33, 274, 822, and 2466 million years, corresponding to the periodicity from a new Universal Cycle model. Based on the results, a fractal model of the universe is hypothesized in which sub-electron fractal matter acts as a dynamic medium for large-scale waves that cause the cycles in astronomical and geological processes. According to this hypothesis, the medium of sub-electron fractal matter periodically compresses and decompresses according to the standard laws for mechanical waves. Consequently, the compressions contribute to high-pressure environments and vice versa for the decompressions, which are hypothesized to cause the

  20. Common origin of positive ionospheric storms at middle latitudes and the geomagnetic activity effect at low latitudes

    International Nuclear Information System (INIS)

    Proelss, G.W.

    1993-01-01

    The author looks for a correlation between two different atmospheric effects. They are a positive atmospheric storm (an anomalous increase in the F2 region ionization density), observed at middle latitudes, and the geomagnetic activity effect (the anomalous changes of temperature and gas density seen in the thermosphere), observed at low latitudes. A temporal correlation is sought to test the argument that both of these effects are the result of travelling atmospheric disturbances (TAD). A TAD is a pulselike atmospheric wave thought to be generated by substorm activity, and to propagate with high velocity (600 m/s) from polar latitudes toward equatorial latitudes. The author looks at data from five separate events correlating magnetic, ionospheric, and neutral atmospheric measurements. The conclusion is that there is a positive correlation between magnetic substorm activity at high latitudes, and positive ionospheric storms at middle latitudes and geomagnetic activity at low latitudes. The time correlations are consistent with high propagation speeds between these events. The author also presents arguments which indicate that the middle latitude positive ionospheric storms are not the result of electric field effects

  1. Geomagnetic Observatory Database February 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) maintains an active database of worldwide geomagnetic observatory...

  2. A re-evaluation of the Italian historical geomagnetic catalogue: implications for paleomagnetic dating at active Italian volcanoes

    Directory of Open Access Journals (Sweden)

    F. D'Ajello Caracciolo

    2011-06-01

    Full Text Available Paleomagnetism is proving to represent one of the most powerful dating tools of volcanics emplaced in Italy during the last few centuries/millennia. This method requires that valuable proxies of the local geomagnetic field (paleosecular variation ((PSV are available. To this end, we re-evaluate the whole Italian geomagnetic directional dataset, consisting of 833 and 696 declination and inclination measurements, respectively, carried out since 1640 AD at several localities. All directions were relocated via the virtual geomagnetic pole method to Stromboli (38.8° N, 15.2° E, the rough centre of the active Italian volcanoes. For declination-only measurements, missing inclinations were derived (always by pole method by French data (for period 1670–1789, and by nearby Italian sites/years (for periods 1640–1657 and 1790–1962. Using post-1825 declination values, we obtain a 0.46 ± 0.19° yr−1 westward drift of the geomagnetic field for Italy. The original observation years were modified, considering such drift value, to derive at a drift-corrected relocated dataset. Both datasets were found to be in substantial agreement with directions derived from the field models by Jackson et al. (2000 and Pavon-Carrasco et al. (2009. However, the drift-corrected dataset minimizes the differences between the Italian data and both field models, and eliminates a persistent 1.6° shift of 1933–1962 declination values from Castellaccio with respect to other nearly coeval Italian data. The relocated datasets were used to calculate two post-1640 Italian SV curves, with mean directions calculated every 30 and 10 years before and after 1790, respectively. The curve comparison suggests that both available field models yield the best available SV curve to perform paleomagnetic dating of 1600–1800 AD Italian volcanics, while the Italian drift-corrected curve is probably preferable for the 19th century. For the 20th century, the global model by

  3. Influence of geomagnetic activity and atmospheric pressure on human arterial pressure during the solar cycle 24

    Science.gov (United States)

    Azcárate, T.; Mendoza, B.; Levi, J. R.

    2016-11-01

    We performed a study of the systolic (SBP) and diastolic (DBP) arterial blood pressure behavior under natural variables such as the atmospheric pressure (AtmP) and the horizontal geomagnetic field component (H). We worked with a sample of 304 healthy normotense volunteers, 152 men and 152 women, with ages between 18 and 84 years in Mexico City during the period 2008-2014, corresponding to the minimum, ascending and maximum phases of the solar cycle 24. The data was divided by gender, age and day/night cycle. We studied the time series using three methods: Correlations, bivariate and superposed epochs (within a window of three days around the day of occurrence of a geomagnetic storm) analysis, between the SBP and DBP and the natural variables (AtmP and H). The correlation analysis indicated correlation between the SBP and DBP and AtmP and H, being the largest during the night. Furthermore, the correlation and bivariate analysis showed that the largest correlations are between the SBP and DBP and the AtmP. The superposed epoch analysis found that the largest number of significant SBP and DBP changes occurred for women. Finally, the blood pressure changes are larger during the solar minimum and ascending solar cycle phases than during the solar maximum; the storms of the minimum were more intense than those of the maximum and this could be the reason of behavior of the blood pressure changes along the solar cycle.

  4. Solar activity effects on cosmic ray intensity and geomagnetic field variation

    International Nuclear Information System (INIS)

    Shukla, A.K.; Shukla, J.P.; Sharma, S.M.; Singh, R.L.; Agrawal, S.P.

    1978-01-01

    An analysis has been performed to statistically correlate the date of solar flare occurrence and its importance with the short term cosmic ray intensity decreases (observed by the high latitude neutron monitors) as well as with the geomagnetic field fluctuation indices (Asub(p) and Dsub(st)), during the period 1973-1976. This period has the particular advantage of being close to a solar minimum to avoid the ambiguity due to closely spaced solar flares. It is found that the intensity decrease starts at least 2-3 days after the date of bright solar flares of Imp 1B, 2B or 3B and the amplitude of the decrease increases with the importance of the solar flare. (author)

  5. Geomagnetic effects caused by rocket exhaust jets

    Directory of Open Access Journals (Sweden)

    Lipko Yu.V.

    2016-09-01

    Full Text Available In the space experiment Radar–Progress, we have made 33 series of measurements of geomagnetic variations during ignitions of engines of Progress cargo spacecraft in low Earth orbit. We used magneto-measuring complexes, installed at observatories of the Institute of Solar-Terrestrial Physics of Siberian Branch of the Russian Academy of Sciences, and magnetotelluric equipment of a mobile complex. We assumed that engine running can cause geomagnetic disturbances in field tubes crossed by the spacecraft. When analyzing experimental data, we took into account the following space weather factors: solar wind parameters, total daily mid-latitude geomagnetic activity index Kр, geomagnetic auroral electrojet index AE, global geomagnetic activity. The empirical data we obtained indicate that 18 of the 33 series showed geomagnetic variations with various periods.

  6. Geomagnetic activity at Northern Hemisphere's mid-latitude ground stations: How much can be explained using TS05 model

    Science.gov (United States)

    Castillo, Yvelice; Pais, Maria Alexandra; Fernandes, João; Ribeiro, Paulo; Morozova, Anna L.; Pinheiro, Fernando J. G.

    2017-12-01

    For the 2007 to 2014 period, we use a statistical approach to evaluate the performance of Tsyganenko and Sitnov [2005] semi-empirical model (TS05) in estimating the magnetospheric transient signal observed at four Northern Hemisphere mid-latitude ground stations: Coimbra, Portugal; Panagyurishte, Bulgary; Novosibirsk, Russia and Boulder, USA. Using hourly mean data, we find that the TS05 performance is clearly better for the X (North-South) than for the Y (East-West) field components and for more geomagnetically active days as determined by local K-indices. In ∼ 50% (X) and ∼ 30% (Y) of the total number of geomagnetically active days, correlation values yield r ≥ 0.7. During more quiet conditions, only ∼ 30% (X) and ∼ 15% (Y) of the number of analyzed days yield r ≥ 0.7. We compute separate contributions from different magnetospheric currents to data time variability and to signal magnitude. During more active days, all tail, symmetric ring and partial ring currents contribute to the time variability of X while the partial ring and field aligned currents contribute most to the time variability of Y. The tail and symmetric ring currents are main contributors to the magnitude of X. In the best case estimations when r ≥ 0.7, remaining differences between observations and TS05 predictions could be explained by global induction in the Earth's upper layers and crustal magnetization. The closing of field aligned currents through the Earth's center in the TS05 model seems to be mainly affecting the Y magnetospheric field predictions.

  7. On polar daily geomagnetic variation

    Directory of Open Access Journals (Sweden)

    Paola De Michelis

    2015-11-01

    Full Text Available The aim of this work is to investigate the nature of the daily magnetic field perturbations produced by ionospheric and magnetospheric currents at high latitudes. We analyse the hourly means of the X and Y geomagnetic field components recorded by a meridian chain of permanent geomagnetic observatories in the polar region of the Northern Hemisphere during a period of four years (1995-1998 around the solar minimum. We apply a mathematical method, known as natural orthogonal component (NOC, which is capable of characterizing the dominant modes of the geomagnetic field daily variability through a set of empirical orthogonal functions (EOFs. Using the first two modes we reconstruct a two-dimensional equivalent current representation of the ionospheric electric currents, which contribute substantially to the geomagnetic daily variations. The obtained current structures resemble the equivalent current patterns of DP2 and DP1. We characterize these currents by studying their evolution with the geomagnetic activity level and by analysing their dependence on the interplanetary magnetic field. The obtained results support the idea of a coexistence of two main processes during all analysed period although one of them, the directly driven process, represents the dominant component of the geomagnetic daily variation.

  8. Large enhancements in low latitude total electron content during 15 May 2005 geomagnetic storm in Indian zone

    Directory of Open Access Journals (Sweden)

    N. Dashora

    2009-05-01

    Full Text Available Results pertaining to the response of the equatorial and low latitude ionosphere to a major geomagnetic storm that occurred on 15 May 2005 are presented. These results are also the first from the Indian zone in terms of (i GPS derived total electron content (TEC variations following the storm (ii Local low latitude electrodynamics response to penetration of high latitude convection electric field (iii effect of storm induced traveling atmospheric disturbances (TAD's on GPS-TEC in equatorial ionization anomaly (EIA zone. Data set comprising of ionospheric TEC obtained from GPS measurements, ionograms from an EIA zone station, New Delhi (Geog. Lat. 28.42° N, Geog. Long. 77.21° E, ground based magnetometers in equatorial and low latitude stations and solar wind data obtained from Advanced Composition Explorer (ACE has been used in the present study. GPS receivers located at Udaipur (Geog. Lat. 24.73° N, Geog. Long. 73.73° E and Hyderabad (Geog. Lat. 17.33° N, Geog. Long. 78.47° E have been used for wider spatial coverage in the Indian zone. Storm induced features in vertical TEC (VTEC have been obtained comparing them with the mean VTEC of quiet days. Variations in solar wind parameters, as obtained from ACE and in the SYM-H index, indicate that the storm commenced on 15 May 2005 at 02:39 UT. The main phase of the storm commenced at 06:00 UT on 15 May with a sudden southward turning of the Z-component of interplanetary magnetic field (IMF-Bz and subsequent decrease in SYM-H index. The dawn-to-dusk convection electric field of high latitude origin penetrated to low and equatorial latitudes simultaneously as corroborated by the magnetometer data from the Indian zone. Subsequent northward turning of the IMF-Bz, and the penetration of the dusk-to-dawn electric field over the dip equator is also discernible. Response of the low latitude ionosphere to this storm may be characterized in terms of (i enhanced background level of VTEC as compared to

  9. Large enhancements in low latitude total electron content during 15 May 2005 geomagnetic storm in Indian zone

    Directory of Open Access Journals (Sweden)

    N. Dashora

    2009-05-01

    Full Text Available Results pertaining to the response of the equatorial and low latitude ionosphere to a major geomagnetic storm that occurred on 15 May 2005 are presented. These results are also the first from the Indian zone in terms of (i GPS derived total electron content (TEC variations following the storm (ii Local low latitude electrodynamics response to penetration of high latitude convection electric field (iii effect of storm induced traveling atmospheric disturbances (TAD's on GPS-TEC in equatorial ionization anomaly (EIA zone.

    Data set comprising of ionospheric TEC obtained from GPS measurements, ionograms from an EIA zone station, New Delhi (Geog. Lat. 28.42° N, Geog. Long. 77.21° E, ground based magnetometers in equatorial and low latitude stations and solar wind data obtained from Advanced Composition Explorer (ACE has been used in the present study. GPS receivers located at Udaipur (Geog. Lat. 24.73° N, Geog. Long. 73.73° E and Hyderabad (Geog. Lat. 17.33° N, Geog. Long. 78.47° E have been used for wider spatial coverage in the Indian zone. Storm induced features in vertical TEC (VTEC have been obtained comparing them with the mean VTEC of quiet days. Variations in solar wind parameters, as obtained from ACE and in the SYM-H index, indicate that the storm commenced on 15 May 2005 at 02:39 UT. The main phase of the storm commenced at 06:00 UT on 15 May with a sudden southward turning of the Z-component of interplanetary magnetic field (IMF-Bz and subsequent decrease in SYM-H index. The dawn-to-dusk convection electric field of high latitude origin penetrated to low and equatorial latitudes simultaneously as corroborated by the magnetometer data from the Indian zone. Subsequent northward turning of the IMF-Bz, and the penetration of the dusk-to-dawn electric field over the dip equator is also discernible. Response of the low latitude ionosphere to this storm may be characterized in terms of (i

  10. Global Distribution and Variations of NO Infrared Radiative Flux and Its Responses to Solar Activity and Geomagnetic Activity in the Thermosphere

    Science.gov (United States)

    Tang, Chaoli; Wei, Yuanyuan; Liu, Dong; Luo, Tao; Dai, Congming; Wei, Heli

    2017-12-01

    The global distribution and variations of NO infrared radiative flux (NO-IRF) are presented during 2002-2016 in the thermosphere covering 100-280 km altitude based on Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) data set. For investigating the spatial variations of the mutual relationship between NO-IRF and solar activity, the altitude ranges from 100 km to 280 km are divided into 90 altitude bins, and the latitude regions of 83°S-83°N are divided into 16 latitude bins. By processing about 1.8E9 NO-IRF observation values from about 5E6 vertical nighttime profiles recorded in SABER data set, we obtained more than 4.1E8 samples of NO-IRF. The annual-mean values of NO-IRF are then calculated by all available NO-IRF samples within each latitude and altitude bin. Local latitudinal maxima in NO-IRF are found between 120 and 145 km altitude, and the maximum NO-IRF located at polar regions are 3 times more than that of the minimum at equatorial region. The influences of solar and geomagnetic activity on the spatial variations of NO-IRF are investigated. Both the NO-IRF and its response to solar and geomagnetic activity show nearly symmetric distribution between the two hemispheres. It is demonstrated that the observed changes in NO-IRF at altitudes between 100 and 225 km correlate well with the changes in solar activity. The NO-IRF at solar maximum is about 4 times than that at solar minimum, and the current maximum of NO-IRF in 2014 is less than 70% of the prior maximum in 2001. For the first time, the response ranges of the NO-IRF to solar and geomagnetic activity at different altitudes and latitudes are reported.

  11. Anomalous enhancement in daytime 40-kHz signal amplitude accompanied by geomagnetic storms, earthquakes and meteor showers

    Directory of Open Access Journals (Sweden)

    B. K. De

    Full Text Available Anomalous propagational characteristics, daytime signal levels greater than night-time, were observed. The amplitude records of a 40-kHz signal propagated over a distance of 5100 km from Sanwa, Japan to Calcutta along a low-latitude path show higher signal strength at midday compared to the midnight level on days preceded by principal geomagnetic storms, earthquakes and major meteor showers. This is explained by the increased ionization in the D-region following geophysical events. The storm after-effects only have a duration of a single day in this low-latitude path.

  12. Anomalous enhancement in daytime 40-kHz signal amplitude accompanied by geomagnetic storms, earthquakes and meteor showers

    Directory of Open Access Journals (Sweden)

    B. K. De

    1995-10-01

    Full Text Available Anomalous propagational characteristics, daytime signal levels greater than night-time, were observed. The amplitude records of a 40-kHz signal propagated over a distance of 5100 km from Sanwa, Japan to Calcutta along a low-latitude path show higher signal strength at midday compared to the midnight level on days preceded by principal geomagnetic storms, earthquakes and major meteor showers. This is explained by the increased ionization in the D-region following geophysical events. The storm after-effects only have a duration of a single day in this low-latitude path.

  13. Statistical analysis of geomagnetic field variations during solar eclipses

    Science.gov (United States)

    Kim, Jung-Hee; Chang, Heon-Young

    2018-04-01

    We investigate the geomagnetic field variations recorded by INTERMAGNET geomagnetic observatories, which are observed while the Moon's umbra or penumbra passed over them during a solar eclipse event. Though it is generally considered that the geomagnetic field can be modulated during solar eclipses, the effect of the solar eclipse on the observed geomagnetic field has proved subtle to be detected. Instead of exploring the geomagnetic field as a case study, we analyze 207 geomagnetic manifestations acquired by 100 geomagnetic observatories during 39 solar eclipses occurring from 1991 to 2016. As a result of examining a pattern of the geomagnetic field variation on average, we confirm that the effect can be seen over an interval of 180 min centered at the time of maximum eclipse on a site of a geomagnetic observatory. That is, demonstrate an increase in the Y component of the geomagnetic field and decreases in the X component and the total strength of the geomagnetic field. We also find that the effect can be overwhelmed, depending more sensitively on the level of daily geomagnetic events than on the level of solar activity and/or the phase of solar cycle. We have demonstrated it by dividing the whole data set into subsets based on parameters of the geomagnetic field, solar activity, and solar eclipses. It is suggested, therefore, that an evidence of the solar eclipse effect can be revealed even at the solar maximum, as long as the day of the solar eclipse is magnetically quiet.

  14. The national geomagnetic initiative

    Science.gov (United States)

    1993-01-01

    The Earth's magnetic field, through its variability over a spectrum of spatial and temporal scales, contains fundamental information on the solid Earth and geospace environment (the latter comprising the atmosphere, ionosphere, and magnetosphere). Integrated studies of the geomagnetic field have the potential to address a wide range of important processes in the deep mantle and core, asthenosphere, lithosphere, oceans, and the solar-terrestrial environment. These studies have direct applications to important societal problems, including resource assessment and exploration, natural hazard mitigation, safe navigation, and the maintenance and survivability of communications and power systems on the ground and in space. Studies of the Earth's magnetic field are supported by a variety of federal and state agencies as well as by private industry. Both basic and applied research is presently supported by several federal agencies, including the National Science Foundation (NSF), U.S. Geological Survey (USGS), U.S. Department of Energy (DOE), National Oceanic and Atmospheric Administration (NOAA), National Aeronautics and Space Administration (NASA), and U.S. Department of Defense (DOD) (through the Navy, Air Force, and Defense Mapping Agency). Although each agency has a unique, well-defined mission in geomagnetic studies, many areas of interest overlap. For example, NASA, the Navy, and USGS collaborate closely in the development of main field reference models. NASA, NSF, and the Air Force collaborate in space physics. These interagency linkages need to be strengthened. Over the past decade, new opportunities for fundamental advances in geomagnetic research have emerged as a result of three factors: well-posed, first-order scientific questions; increased interrelation of research activities dealing with geomagnetic phenomena; and recent developments in technology. These new opportunities can be exploited through a national geomagnetic initiative to define objectives and

  15. Geomagnetic Principal Magnetic Storms

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The abbreviations used for observatory names are as follows: GEOMAGNETIC OBSERVATORIES Code Station Geomagnetic Latitude ABG Alibag AMS Martin de Vivie. These data...

  16. Biological effects of geomagnetic storms

    International Nuclear Information System (INIS)

    Chibisov, S.M.; Breus, T.K.; Levitin, A.E.; Drogova, G.M.; AN SSSR, Moscow; AN SSSR, Moscow

    1995-01-01

    Six physiological parameters of cardio-vascular system of rabbits and ultrastructure of cardiomyocytes were investigated during two planetary geomagnetic storms. At the initial and main phase of the storm the normal circadian structure in each cardiovascular parameter was lost. The disynchronozis was growing together with the storm and abrupt drop of cardia activity was observed during the main phase of storm. The main phase of storm followed by the destruction and degradation of cardiomyocytes. Parameters of cardia activity became substantially synchronized and characterized by circadian rhythm structure while the amplitude of deviations was still significant at the recovery stage of geomagnetic storm. 3 refs.; 7 figs

  17. Long-term north-south asymmetry in solar wind speed inferred from geomagnetic activity: A new type of century-scale solar oscillation?

    DEFF Research Database (Denmark)

    Mursula, K.; Zieger, B.

    2001-01-01

    A significant and very similar annual variation in solar wind speed and in geomagnetic activity was recently found around all the four solar cycle minima covered by direct SW observations since mid-1960's. We have shown that the phase of this annual variation reverses with the Sun's polarity...... reversal, depicting a new form of 22-year periodicity. The annual variation results from a small north-south asymmetry in SW speed distribution where the minimum speed region is shifted toward the northern magnetic hemisphere. Here we study the very long-term evolution of the annual variation using early...... registrations of geomagnetic activity. We find a significant annual variation during the high-activity solar cycles in mid-19th century and since 1930's. Most interestingly, the SW speed asymmetry in mid-19th century was opposite to the present asymmetry, i.e., the minimum speed region was then shifted toward...

  18. New insights on geomagnetic storms from observations and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Jordanova, Vania K [Los Alamos National Laboratory

    2009-01-01

    Understanding the response at Earth of the Sun's varying energy output and forecasting geomagnetic activity is of central interest to space science, since intense geomagnetic storms may cause severe damages on technological systems and affect communications. Episodes of southward (Bzgeomagnetic conditions are associated either with coronal mass ejections (CMEs) and possess long and continuous negative IMF Bz excursions, or with high speed solar wind streams (HSS) whose geoeffectiveness is due to IMF Bz profiles fluctuating about zero with various amplitudes and duration. We show examples of ring current simulations during two geomagnetic storms representative of each interplanetary condition with our kinetic ring current atmosphere interactions model (RAM), and investigate the mechanisms responsible for trapping particles and for causing their loss. We find that periods of increased magnetospheric convection coinciding with enhancements of plasma sheet density are needed for strong ring current buildup. During the HSS-driven storm the convection potential is highly variable and causes small sporadic injections into the ring current. The long period of enhanced convection during the CME-driven storm causes a continuous ring current injection penetrating to lower L shells and stronger ring current buildup.

  19. Following solar activity with geomagnetic and cosmic-ray ground-based stations in the Iberian Peninsula region

    Science.gov (United States)

    Villasante-Marcos, Victor; José Blanco, Juan; Miquel Torta, Joan; Catalán, Manuel; Ribeiro, Paulo; Morozova, Anna; Tordesillas, José Manuel; Solé, Germán; Gomis-Moreno, Almudena

    2016-04-01

    The Iberian Peninsula is located in the South-West of Europe between 36°00' N and 43°47' N and between 9°29' W and 3°19' E. There are four Geomagnetic Observatories currently operative in this area devoted to the observation of the Earth's magnetic field: Observatori de l'Ebre (NE Spain); Observatorio de San Pablo de los Montes (central Spain); Observatorio de San Fernando (southern Spain); Observatório de Coimbra (central Portugal); plus another one, Observatorio de Güímar, in Tenerife (Canary Islands, Spain). There is also one neutron monitor located in Guadalajara (central Spain; 40°38' N, 3°9' W at 708 m asl) continuously measuring the arrival of cosmic rays to the Earth's surface. In this work we show combined observations of these six stations during events caused by solar activity. We analyze them looking for differences that could imply extremely local effects caused by the response of the Earth's magnetosphere and ionosphere to solar activity.

  20. Daily variation characteristics at polar geomagnetic observatories

    Science.gov (United States)

    Lepidi, S.; Cafarella, L.; Pietrolungo, M.; Di Mauro, D.

    2011-08-01

    This paper is based on the statistical analysis of the diurnal variation as observed at six polar geomagnetic observatories, three in the Northern and three in the Southern hemisphere. Data are for 2006, a year of low geomagnetic activity. We compared the Italian observatory Mario Zucchelli Station (TNB; corrected geomagnetic latitude: 80.0°S), the French-Italian observatory Dome C (DMC; 88.9°S), the French observatory Dumont D'Urville (DRV; 80.4°S) and the three Canadian observatories, Resolute Bay (RES; 83.0°N), Cambridge Bay (CBB; 77.0°N) and Alert (ALE, 87.2°N). The aim of this work was to highlight analogies and differences in daily variation as observed at the different observatories during low geomagnetic activity year, also considering Interplanetary Magnetic Field conditions and geomagnetic indices.

  1. Variations of plasmaspheric field-aligned electron and ion densities (90-4000 km) during quiet to moderately active (Kp < 4) geomagnetic conditions

    Science.gov (United States)

    Sonwalkar, V. S.; Reddy, A.

    2017-12-01

    Variation in field-aligned electron and ion densities as a function of geomagnetic activity are important parameters in the physics of the thermosphere-ionosphere-magnetosphere coupling. Using whistler mode sounding from IMAGE, we report variations in field-aligned electron density and O+/H+ transition height (HT) during two periods (16-23 Aug 2005; 24 Sep-06 Oct 2005) when geomagnetic conditions were quiet (maximum Kp in the past 24 hours, Kpmax,24 ≤ 2) to moderately active (2 quiet time, during moderate geomagnetic activity: (1) O+/H+ transition height was roughly same; (2) electron density variations below HT showed no trend; (3) electron density above HT increased ( 10-40 %). The measured electron density is in agreement with in situ measurements from CHAMP (350 km) and DMSP (850 km) and past space borne (e. g., ISIS) measurements but the F2 peak density is a factor of 2 lower relative to that measured by ground ionosondes and that predicted by IRI-2012 empirical model. The measured transition height is consistent with OGO 4, Explorer 31, and C/NOFS measurements but is lower than that from IRI-2012. The observed variations in electron density at F2 peak are consistent with past work and are attributed to solar, geomagnetic, and meteorological causes [e. g. Risibeth and Mendillo, 2001; Forbes et al., 2000]. To the best of our knowledge, variations in field-aligned electron density above transition height at mid-latitudes during quiet to moderately active periods have not been reported in the past. Further investigation using physics based models (e. g., SAMI3) is required to explain the observed variations.

  2. Radar observations of high-latitude lower-thermospheric and upper-mesospheric winds and their response to geomagnetic activity

    International Nuclear Information System (INIS)

    Johnson, R.M.

    1987-01-01

    Observations made by the Chatanika, Alaska, incoherent scatter radar during the summer months of 1976 to 1081 are analyzed to obtain high resolution lower-thermospheric neutral winds. Average winds and their tidal components are presented and compared to previous observational and model results. Upper-mesospheric neutral-wind observations obtained by the Poke Flat, Alaska Mesosphere-Stratosphere-Troposphere (MST) radar during the summer months of 1980 to 1982 are investigated statistically for evidence of variations due to geomagnetic activity. Observation of upper-mesospheric neutral winds made during two energetic Solar Proton Events (SPEs) by the Poker Flat, MST radar are presented. These results allow the low-altitude limits of magnetospheric coupling to the neutral atmosphere to be determined. Lower-thermospheric neutral winds are coupled to the ion convection driven by typical magnetospheric forcing above about 100 km. Coupling to lower atmospheric levels does not occur except during intervals of extreme disturbance of the magnetosphere-ionosphere-thermosphere system which are also accompanied by dramatically increased ionization in the high-latitude mesosphere, such as SPEs

  3. Review Article: On the relation between the seismic activity and the Hurst exponent of the geomagnetic field at the time of the 2000 Izu swarm

    Directory of Open Access Journals (Sweden)

    F. Masci

    2013-09-01

    Full Text Available Many papers document the observation of earthquake-related precursory signatures in geomagnetic field data. However, the significance of these findings is ambiguous because the authors did not adequately take into account that these signals could have been generated by other sources, and the seismogenic origin of these signals have not been validated by comparison with independent datasets. Thus, they are not reliable examples of magnetic disturbances induced by the seismic activity. Hayakawa et al. (2004 claim that at the time of the 2000 Izu swarm the Hurst exponent of the Ultra-Low-Frequency (ULF: 0.001–10 Hz band of the geomagnetic field varied in accord with the energy released by the seismicity. The present paper demonstrates that the behaviour of the Hurst exponent was insufficiently investigated and also misinterpreted by the authors. We clearly show that during the Izu swarm the changes of the Hurst exponent were strongly related to the level of global geomagnetic activity and not to the increase of the local seismic activity.

  4. Reconstruction of geomagnetic activity and near-Earth interplanetary conditions over the past 167 yr – Part 2: A new reconstruction of the interplanetary magnetic field

    Directory of Open Access Journals (Sweden)

    M. Lockwood

    2013-11-01

    Full Text Available We present a new reconstruction of the interplanetary magnetic field (IMF, B for 1846–2012 with a full analysis of errors, based on the homogeneously constructed IDV(1d composite of geomagnetic activity presented in Part 1 (Lockwood et al., 2013a. Analysis of the dependence of the commonly used geomagnetic indices on solar wind parameters is presented which helps explain why annual means of interdiurnal range data, such as the new composite, depend only on the IMF with only a very weak influence of the solar wind flow speed. The best results are obtained using a polynomial (rather than a linear fit of the form B = χ · (IDV(1d − βα with best-fit coefficients χ = 3.469, β = 1.393 nT, and α = 0.420. The results are contrasted with the reconstruction of the IMF since 1835 by Svalgaard and Cliver (2010.

  5. Geomagnetic signal induced by the M5.7 earthquake occurred on September 24-th, 2016, in the seismic active Vrancea zone, Romania

    Science.gov (United States)

    Stanica, Dumitru; Armand Stanica, Dragos

    2017-04-01

    In this paper, we used the geomagnetic time series collected in real time by the electromagnetic monitoring system, placed at the Geomagnetic Observatory Provita de Sus, to emphasize possible relationships between the pre-seismic anomalous behavior of the normalized function Bzn and M5.7 earthquake occurrence in Vrancea seismic active zone, on September 24, 2016. It has already been demonstrated (Stanica and Stanica, 2012, Stanica et al., 2015) that for a 2D geoelectric structure, in pre-seismic conditions, the normalized function Bzn has significant changes in magnitudes due to the electrical conductivity changes, possibly associated with the earthquake-induced rupture-processes and high-pressure fluid flow through the faulting systems developed inside the Vrancea seismogenic volume and along the Carpathian electrical conductivity anomaly. In this circumstances, the daily mean distributions of the Bzn = Bz/Bperp (where Bz is vertical component of the geomagnetic field; Bperp is geomagnetic component perpendicular to the geoelectric strike) and its standard deviation (SD) are performed in the ULF frequency range 0.001Hz to 0.0083Hz by using both the FFT band-pass filter analysis and statistical analysis based on a standardized random variable equation. After analyzing the pre-seismic anomalous intervals, a pre-seismic geomagnetic signal greater than 5 SD was identified on September 22, 2016, what means a lead time of 2 days before the M5.7 earthquake occurred on September 24, emphasized in real time on the web site (www.geodin.ro). The final conclusion is that the proposed geomagnetic methodology might be used to provide suitable information for the extreme seismic hazard assessment and risk mitigation. References: Dumitru Stanica and Dragos Armand Stanica, Earthquakes precursors, in "Earthquake Research and Analysis-Statistical Studies, Observations and Planning" Book 5, edited by: Dr. Sebastiano D'Amico, ISBN 978-953-51-0134-5, InTech open access publisher

  6. Atmospheric loss from the dayside open polar region and its dependence on geomagnetic activity: implications for atmospheric escape on evolutionary timescales

    Directory of Open Access Journals (Sweden)

    R. Slapak

    2017-06-01

    Full Text Available We have investigated the total O+ escape rate from the dayside open polar region and its dependence on geomagnetic activity, specifically Kp. Two different escape routes of magnetospheric plasma into the solar wind, the plasma mantle, and the high-latitude dayside magnetosheath have been investigated separately. The flux of O+ in the plasma mantle is sufficiently fast to subsequently escape further down the magnetotail passing the neutral point, and it is nearly 3 times larger than that in the dayside magnetosheath. The contribution from the plasma mantle route is estimated as  ∼ 3. 9 × 1024exp(0. 45 Kp [s−1] with a 1 to 2 order of magnitude range for a given geomagnetic activity condition. The extrapolation of this result, including escape via the dayside magnetosheath, indicates an average O+ escape of 3 × 1026 s−1 for the most extreme geomagnetic storms. Assuming that the range is mainly caused by the solar EUV level, which was also larger in the past, the average O+ escape could have reached 1027–28 s−1 a few billion years ago. Integration over time suggests a total oxygen escape from ancient times until the present roughly equal to the atmospheric oxygen content today.

  7. Acceleration and loss of relativistic electrons during small geomagnetic storms.

    Science.gov (United States)

    Anderson, B R; Millan, R M; Reeves, G D; Friedel, R H W

    2015-12-16

    Past studies of radiation belt relativistic electrons have favored active storm time periods, while the effects of small geomagnetic storms ( D s t  > -50 nT) have not been statistically characterized. In this timely study, given the current weak solar cycle, we identify 342 small storms from 1989 through 2000 and quantify the corresponding change in relativistic electron flux at geosynchronous orbit. Surprisingly, small storms can be equally as effective as large storms at enhancing and depleting fluxes. Slight differences exist, as small storms are 10% less likely to result in flux enhancement and 10% more likely to result in flux depletion than large storms. Nevertheless, it is clear that neither acceleration nor loss mechanisms scale with storm drivers as would be expected. Small geomagnetic storms play a significant role in radiation belt relativistic electron dynamics and provide opportunities to gain new insights into the complex balance of acceleration and loss processes.

  8. Geomagnetic field of earth

    International Nuclear Information System (INIS)

    Delipetrev, Marjan; Delipetrev, Blagoj; Panovska, Sanja

    2008-01-01

    In this paper is introduced the theory of geomagnetic field of the Earth. A homogenous and isotropic sphere is taken for a model of Earth with a bar magnet at its center as a magnetic potential. The understanding of the real origin of geomagnetic field produced from differential rotation of inner core with respect to the outer core of Earth is here presented. Special attention is given to the latest observed data of the established net of geomagnetic repeat stations in the Republic of Macedonia. Finally, the maps of elements of geomagnetic field and the equation for calculation of normal magnetic field of Earth are provided. (Author)

  9. Average energetic ion flux variations associated with geomagnetic activity from EPIC/STICS on Geotail

    Science.gov (United States)

    Christon, S. P.; Gloeckler, G.; Eastman, T. E.; McEntire, R. W.; Roelef, E. C.; Lui, A. T. Y.; Williams, D. J.; Frank, L. A.; Paterson, W. R.; Kokubun, S.; hide

    1996-01-01

    The magnetotail ion flux measurements from the Geotail spacecraft are analyzed both with and without the application of selection criteria that identify the plasma regime in which an observation is obtained. The different results are compared with each other. The initial results on the changes of energetic ion flux and composition correlated to average substorm activity in different magnetotail plasma regimes are discussed. The energetic ions are measured using the energetic particles and ion composition (EPIC) experiment and the suprathermal ion composition spectrometer (STICS). The plasma, wave and field instruments of the Geotail satellite were used to identify the principle magnetotail plasma regimes of plasma sheet, lobe, and magnetospheric boundary layer, as well as the magnetosheath and solar wind. Energetic O and H ions were observed in all the plasma regimes.

  10. Pc3 activity at low geomagnetic latitudes - A comparison with solar wind observations

    Science.gov (United States)

    Villante, U.; Lepidi, S.; Vellante, M.; Lazarus, A. J.; Lepping, R. P.

    1992-01-01

    On an hourly time-scale the different roles of the solar wind and interplanetary magnetic field (IMF) parameters on ground micropulsation activity can be better investigated than at longer time-scales. A long-term comparison between ground measurements made at L'Aquila and IMP 8 observations confirms the solar wind speed as the key parameter for the onset of pulsations even at low latitudes, although additional control of the energy transfer from the interplanetary medium to the earth's magnetosphere is clearly exerted by the cone angle. Above about 20 mHz the frequency of pulsations is confirmed to be closely related to the IMF magnitude while, in agreement with model predictions, the IMF magnitude is related to the amplitude of the local fundamental resonant mode. We provide an interesting example in which high resolution measurements simultaneously obtained in the foreshock region and on the ground show that external transversal fluctuations do not penetrate deep into the low latitude magnetosphere.

  11. Pc3 activity at low geomagnetic latitudes: a comparison with solar wind observations

    Energy Technology Data Exchange (ETDEWEB)

    Villante, U.; Lepidi, S.; Vellante, M. (L' Aquila Univ. (Italy). Dip. di Fisica); Lazarus, A.J. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Center for Space Research Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics); Lepping, R.P. (National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center)

    1992-10-01

    On an hourly time-scale the different roles of the solar wind and interplanetary magnetic field (IMF) parameters on ground micropulsation activity can be better investigated than at longer time-scales. A long-term comparison between ground measurements made at L'Aquila (L [approx equal] 1.6) and IMP 8 observations confirms the solar wind speed as the key parameter for the onset of pulsations even at low latitudes, although additional control of the energy transfer from the interplanetary medium to the Earth's magnetosphere is clearly exerted by the cone angle. Above [approx equal] 20 mHz the frequency of pulsations is confirmed to be closely related to the IMF magnitude while, in agreement with model predictions, the IMF magnitude is related to the amplitude of the local fundamental resonant mode. We provide an interesting example in which high resolution measurements simultaneously obtained in the foreshock region and on the ground show that external transversal fluctuations do not penetrate deep into the low latitude magnetosphere. (Author).

  12. Dynamical complexity detection in geomagnetic activity indices using wavelet transforms and Tsallis entropy

    Science.gov (United States)

    Balasis, G.; Daglis, I. A.; Papadimitriou, C.; Kalimeri, M.; Anastasiadis, A.; Eftaxias, K.

    2008-12-01

    Dynamical complexity detection for output time series of complex systems is one of the foremost problems in physics, biology, engineering, and economic sciences. Especially in magnetospheric physics, accurate detection of the dissimilarity between normal and abnormal states (e.g. pre-storm activity and magnetic storms) can vastly improve space weather diagnosis and, consequently, the mitigation of space weather hazards. Herein, we examine the fractal spectral properties of the Dst data using a wavelet analysis technique. We show that distinct changes in associated scaling parameters occur (i.e., transition from anti- persistent to persistent behavior) as an intense magnetic storm approaches. We then analyze Dst time series by introducing the non-extensive Tsallis entropy, Sq, as an appropriate complexity measure. The Tsallis entropy sensitively shows the complexity dissimilarity among different "physiological" (normal) and "pathological" states (intense magnetic storms). The Tsallis entropy implies the emergence of two distinct patterns: (i) a pattern associated with the intense magnetic storms, which is characterized by a higher degree of organization, and (ii) a pattern associated with normal periods, which is characterized by a lower degree of organization.

  13. Formation Mechanisms of the Spring-Autumn Asymmetry of the Midlatitudinal NmF2 under Daytime Quiet Geomagnetic Conditions at Low Solar Activity

    Science.gov (United States)

    Pavlov, A. V.; Pavlova, N. M.

    2018-05-01

    Formation mechanism of the spring-autumn asymmetry of the F2-layer peak electron number density of the midlatitudinal ionosphere, NmF2, under daytime quiet geomagnetic conditions at low solar activity are studied. We used the ionospheric parameters measured by the ionosonde and incoherent scatter radar at Millstone Hill on March 3, 2007, March 29, 2007, September 12, 2007, and September 18, 1984. The altitudinal profiles of the electron density and temperature were calculated for the studied conditions using a one-dimensional, nonstationary, ionosphere-plasmasphere theoretical model for middle geomagnetic latitudes. The study has shown that there are two main factors contributing to the formation of the observed spring-autumn asymmetry of NmF2: first, the spring-autumn variations of the plasma drift along the geomagnetic field due to the corresponding variations in the components of the neutral wind velocity, and, second, the difference between the composition of the neutral atmosphere under the spring and autumn conditions at the same values of the universal time and the ionospheric F2-layer peak altitude. The seasonal variations of the rate of O+(4S) ion production, which are associated with chemical reactions with the participation of the electronically excited ions of atomic oxygen, does not significantly affect the studied NmF2 asymmetry. The difference in the degree of influence of O+(4S) ion reactions with vibrationally excited N2 and O2 on NmF2 under spring and autumn conditions does not significantly change the spring-autumn asymmetry of NmF2.

  14. Geomagnetic field, global pattern

    OpenAIRE

    Macmillan, Susan

    2011-01-01

    The geomagnetic field is generated in the fluid outer core region of the Earth by electrical currents flowing in the slowly moving molten iron. In addition to sources in the Earth’s core, the geomagnetic field observable on the Earth’s surface has sources in the crust and in the ionosphere and magnetosphere. The signal from the core dominates, accounting for over 95% of the field at the Earth’s surface. The geomagnetic field varies on a range of scales, both temporal and spatial; the...

  15. Quasi-biennial oscillations in the geomagnetic field: Their global characteristics and origin

    DEFF Research Database (Denmark)

    Ou, Jiaming; Du, Aimin; Finlay, Chris

    2017-01-01

    of second-order derivatives of the geomagnetic X, Y, and Z components reveals salient QBO signals at periods of 1.3, 1.7, 2.2, 2.9, and 5.0 years, with the most prominent peak at 2.2 years. The signature of geomagnetic QBO is generally stronger in the X and Z components and with larger amplitudes...... on geomagnetically disturbed days. The amplitude of the QBO in the X component decreases from the equator to the poles, then shows a local maximum at subauroral and auroral zones. The QBO in the Z component enhances from low latitudes toward the polar regions. At high latitudes (poleward of 50°) the geomagnetic QBO...... exhibits stronger amplitudes during LT 00:00–06:00, depending strongly on the geomagnetic activity level, while at low latitudes the main effect is in the afternoon sector. These results indicate that the QBOs at low-to-middle latitudes and at high latitudes are influenced by different magnetospheric...

  16. Geomagnetic Storm Sudden Commencements

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Storm Sudden Commencements (ssc) 1868 to present: STORM1 and STORM2 Lists: (Some text here is taken from the International Association of Geomagnetism and Aeronomy...

  17. Geomagnetic Indices Bulletin (GIB)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Geomagnetic Indices Bulletin is a one page sheet containing the magnetic indices Kp, Ap, Cp, An, As, Am and the provisional aa indices. The bulletin is published...

  18. Geomagnetic aa Indices

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The geomagnetic aa indices are the continuation of the series beginning in the year 1868. A full description of these indices is given in the International...

  19. Long-term predictive assessments of solar and geomagnetic activities made on the basis of the close similarity between the solar inertial motions in the intervals 1840–1905 and 1980–2045

    Czech Academy of Sciences Publication Activity Database

    Charvátová, Ivanka

    2009-01-01

    Roč. 14, č. 1 (2009), s. 25-30 ISSN 1384-1076 R&D Projects: GA AV ČR(CZ) IAA300120608 Institutional research plan: CEZ:AV0Z30120515 Keywords : solar inertial motion * solar activity * geomagnetic activity * long-term predictive assessments Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.675, year: 2009

  20. The Contribution of a Geophysical Data Service: The International Service of Geomagnetic Indices

    Directory of Open Access Journals (Sweden)

    M Menvielle

    2013-01-01

    Full Text Available Geomagnetic indices are basic data in Solar-Terrestrial physics and in operational Space Weather activities. The International Service of Geomagnetic Indices (ISGI is in charge of the derivation and dissemination of the geomagnetic indices that are acknowledged by the International Association of Geomagnetism and Aeronomy (IAGA, an IUGG association. Institutes that are not part of ISGI started early in the Internet age to circulate on-line preliminary values of geomagnetic indices. In the absence of quality stamping, this resulted in a very confusing situation. The ISGI label was found to be the simplest and the safest way to insure quality stamping of circulated geomagnetic indices.

  1. Enhanced NIF neutron activation diagnostics.

    Science.gov (United States)

    Yeamans, C B; Bleuel, D L; Bernstein, L A

    2012-10-01

    The NIF neutron activation diagnostic suite relies on removable activation samples, leading to operational inefficiencies and a fundamental lower limit on the half-life of the activated product that can be observed. A neutron diagnostic system measuring activation of permanently installed samples could remove these limitations and significantly enhance overall neutron diagnostic capabilities. The physics and engineering aspects of two proposed systems are considered: one measuring the (89)Zr/(89 m)Zr isomer ratio in the existing Zr activation medium and the other using potassium zirconate as the activation medium. Both proposed systems could improve the signal-to-noise ratio of the current system by at least a factor of 5 and would allow independent measurement of fusion core velocity and fuel areal density.

  2. Editorial: Topical Volume on Earth's Magnetic Field - Understanding Geomagnetic Sources from the Earth's Interior and its Environment

    DEFF Research Database (Denmark)

    Stolle, Claudia; Olsen, Nils; Richmond, Arthur D.

    2017-01-01

    (seconds to days) magnetic field variations that are caused by currents in the ionosphere and magnetosphere when solar activity, and correspondingly the electric currents in Earth’s environment, are enhanced. However, for studying the internal sources of the geomagnetic field, originating in the core...

  3. Regional TEC model under quiet geomagnetic conditions and low-to-moderate solar activity based on CODE GIMs

    Science.gov (United States)

    Feng, Jiandi; Jiang, Weiping; Wang, Zhengtao; Zhao, Zhenzhen; Nie, Linjuan

    2017-08-01

    Global empirical total electron content (TEC) models based on TEC maps effectively describe the average behavior of the ionosphere. However, the accuracy of these global models for a certain region may not be ideal. Due to the number and distribution of the International GNSS Service (IGS) stations, the accuracy of TEC maps is geographically different. The modeling database derived from the global TEC maps with different accuracy is likely one of the main reasons that limits the accuracy of the new models. Moreover, many anomalies in the ionosphere are geographic or geomagnetic dependent, and as such the accuracy of global models can deteriorate if these anomalies are not fully incorporated into the modeling approach. For regional models built in small areas, these influences on modeling are immensely weakened. Thus, the regional TEC models may better reflect the temporal and spatial variations of TEC. In our previous work (Feng et al., 2016), a regional TEC model TECM-NEC is proposed for northeast China. However, this model is only directed against the typical region of Mid-latitude Summer Nighttime Anomaly (MSNA) occurrence, which is meaningless in other regions without MSNA. Following the technique of TECM-NEC model, this study proposes another regional empirical TEC model for other regions in mid-latitudes. Taking a small area BeiJing-TianJin-Tangshan (JJT) region (37.5°-42.5° N, 115°-120° E) in China as an example, a regional empirical TEC model (TECM-JJT) is proposed using the TEC grid data from January 1, 1999 to June 30, 2015 provided by the Center for Orbit Determination in Europe (CODE) under quiet geomagnetic conditions. The TECM-JJT model fits the input CODE TEC data with a bias of 0.11TECU and a root mean square error of 3.26TECU. Result shows that the regional model TECM-JJT is consistent with CODE TEC data and GPS-TEC data.

  4. [Can solar/geomagnetic activity restrict the occurrence of some shellfish poisoning outbreaks? The example of PSP caused by Gymnodinium catenatum at the Atlantic Portuguese coast].

    Science.gov (United States)

    Vale, P

    2013-01-01

    Cyclic outbreaks of accumulation of paralytic shellfish poisoning (PSP) toxins in mussels attributed to Gymnodinium catenatum blooms displayed several of the highest inter-annual maxima coincidental with minima of the 11-year solar sunspot number (SSN) cycle. The monthly distribution of PSP was associated with low levels of the solar radio flux, a more quantitative approach than SSN for fluctuations in solar activity. A comparison between monthly distribution of PSP and other common biotoxins (okadaic acid (OA), dinophysistoxin-2 (DTX2) and amnesic shellfish poisoning (ASP) toxins) demonstrated that only PSP was significantly associated with low levels of radio flux (p < 0.01). PSP occurrence suggests a prior decline in solar activity could be required to act as a trigger, in a similar manner to a photoperiodic signal. The seasonal frequency increased towards autumn during the study period, which might be related to the progressive atmospheric cut-off of deleterious radiation associated with the seasonal change in solar declination, and might play an additional role in seasonal signal-triggering. PSP distribution was also associated with low levels of the geomagnetic index Aa. A comparison between monthly distribution of PSP and other common biotoxins, also demonstrated that only PSP was significantly associated with low levels of the Aa index (p < 0.01). In some years of SSN minima no significant PSP-outbreaks in mussels were detected. This was attributed to a steady rise in geomagnetic activity that could disrupt the triggering signal. Global distribution patterns show that hotspots for G. catenatum blooms are regions with deficient crustal magnetic anomalies. In addition to the variable magnetic field mostly of solar origin, static fields related to magnetized rocks in the crust and upper mantle might play a role in restricting worldwide geographic distribution.

  5. Geomagnetic response to solar and interplanetary disturbances

    Directory of Open Access Journals (Sweden)

    Maris Georgeta

    2013-07-01

    Full Text Available The space weather discipline involves different physical scenarios, which are characterised by very different physical conditions, ranging from the Sun to the terrestrial magnetosphere and ionosphere. Thanks to the great modelling effort made during the last years, a few Sun-to-ionosphere/thermosphere physics-based numerical codes have been developed. However, the success of the prediction is still far from achieving the desirable results and much more progress is needed. Some aspects involved in this progress concern both the technical progress (developing and validating tools to forecast, selecting the optimal parameters as inputs for the tools, improving accuracy in prediction with short lead time, etc. and the scientific development, i.e., deeper understanding of the energy transfer process from the solar wind to the coupled magnetosphere-ionosphere-thermosphere system. The purpose of this paper is to collect the most relevant results related to these topics obtained during the COST Action ES0803. In an end-to-end forecasting scheme that uses an artificial neural network, we show that the forecasting results improve when gathering certain parameters, such as X-ray solar flares, Type II and/or Type IV radio emission and solar energetic particles enhancements as inputs for the algorithm. Regarding the solar wind-magnetosphere-ionosphere interaction topic, the geomagnetic responses at high and low latitudes are considered separately. At low latitudes, we present new insights into temporal evolution of the ring current, as seen by Burton’s equation, in both main and recovery phases of the storm. At high latitudes, the PCC index appears as an achievement in modelling the coupling between the upper atmosphere and the solar wind, with a great potential for forecasting purposes. We also address the important role of small-scale field-aligned currents in Joule heating of the ionosphere even under non-disturbed conditions. Our scientific results in

  6. International Geomagnetic Reference Field

    DEFF Research Database (Denmark)

    Finlay, Chris; Maus, S.; Beggan, C. D.

    2010-01-01

    The eleventh generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2009 by the International Association of Geomagnetism and Aeronomy Working Group V‐MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field...... model for epoch 2010.0, and a linear predictive secular variation model for 2010.0–2015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity...

  7. Helio-Geomagnetic Activity and the Time Distribution of Myocardial Infractions during the Solar Cycle 23 (1997-2007). A Preliminary Study based on a Greek Hospital Data

    Science.gov (United States)

    Moussas, X.; Preka-Papadema, P.; Apostolou, Th.; Katsavrias, Ch.; Theodoropoulou, A.; Papadima, Th.

    2010-01-01

    We present the time distribution of a large number (7798) of Myocardial Infractions (MI) recorded at the General Hospital `St. Panteleimon' of the city of Nikea (in Piraeus, Greece), during time interval 1997-2007. This data set consisted of 5160 NON-STEACS (non-ST) and 2638 STEACS (ST) infractions are examined along with the monthly numbers of solar flares and Coronal Mass Ejections (CMEs), solar wind parameters and the geomagnetic activity (Dst geomagnetic index and other). The mean monthly value of ST and non-ST events is 20 and 40 respectively. The maximum monthly value of non-ST events (72 and 73) are recorded in October 2002 and January 2003, as well as the one of ST events (32), while solar maximum, recorded in November 2002. This time interval is characterized by magnetic storms from August 2002 peaked in October 2002 and ended in February 2003. It is noticeable that August 2002 corresponds to the solar maximum of CMEs and strong solar flares monthly values. The maximum monthly value of ST events (40) is recorded in November 2005 almost simultaneously with a sudden absence of solar flares (October 2005). Increased values have been recorded during a period of extreme solar events of October-November 2003 and January-March 2005. It seems from this extensive statistical study that there is an association between the monthly values of MI and of CMEs; the non-ST MI shows a better association with CMEs. Moreover, the MI yearly distribution is in accordance with the time distribution of magnetic storms (number and duration). The non-ST distribution is also affected by intense magnetic storms.

  8. Influence of geomagnetic activity and earth weather changes on heart rate and blood pressure in young and healthy population.

    Science.gov (United States)

    Ozheredov, V A; Chibisov, S M; Blagonravov, M L; Khodorovich, N A; Demurov, E A; Goryachev, V A; Kharlitskaya, E V; Eremina, I S; Meladze, Z A

    2017-05-01

    There are many references in the literature related to connection between the space weather and the state of human organism. The search of external factors influence on humans is a multi-factor problem and it is well known that humans have a meteo-sensitivity. A direct problem of finding the earth weather conditions, under which the space weather manifests itself most strongly, is discussed in the present work for the first time in the helio-biology. From a formal point of view, this problem requires identification of subset (magnetobiotropic region) in three-dimensional earth's weather parameters such as pressure, temperature, and humidity, corresponding to the days when the human body is the most sensitive to changes in the geomagnetic field variations and when it reacts by statistically significant increase (or decrease) of a particular physiological parameter. This formulation defines the optimization of the problem, and the solution of the latter is not possible without the involvement of powerful metaheuristic methods of searching. Using the algorithm of differential evolution, we prove the existence of magnetobiotropic regions in the earth's weather parameters, which exhibit magneto-sensitivity of systolic, diastolic blood pressure, and heart rate of healthy young subjects for three weather areas (combinations of atmospheric temperature, pressure, and humidity). The maximum value of the correlation confidence for the measurements attributable to the days of the weather conditions that fall into each of three magnetobiotropic areas is an order of 0.006, that is almost 10 times less than the confidence, equal to 0.05, accepted in many helio-biological researches.

  9. Application of the SP algorithm to the INTERMAGNET magnetograms of the disturbed geomagnetic field

    Science.gov (United States)

    Sidorov, R. V.; Soloviev, A. A.; Bogoutdinov, Sh. R.

    2012-05-01

    The algorithmic system developed in the Laboratory of Geoinformatics at the Geophysical Center, Russian Academy of Sciences, which is intended for recognizing spikes on the magnetograms from the global network INTERMAGNET provides the possibility to carry out retrospective analysis of the magnetograms from the World Data Centers. Application of this system to the analysis of the magnetograms allows automating the job of the experts-interpreters on identifying the artificial spikes in the INTERMAGNET data. The present paper is focused on the SP algorithm (abbreviated from SPIKE) which recognizes artificial spikes on the records of the geomagnetic field. Initially, this algorithm was trained on the magnetograms of 2007 and 2008, which recorded the quiet geomagnetic field. The results of training and testing showed that the algorithm is quite efficient. Applying this method to the problem of recognizing spikes on the data for periods of enhanced geomagnetic activity is a separate task. In this short communication, we present the results of applying the SP algorithm trained on the data of 2007 to the INTERMAGNET magnetograms for 2003 and 2005 sampled every minute. This analysis shows that the SP algorithm does not exhibit a worse performance if applied to the records of a disturbed geomagnetic field.

  10. Geomagnetic radioflash unfold (GRUF)

    International Nuclear Information System (INIS)

    Malik, J.S.

    1975-08-01

    A method of inverting the geomagnetic component of the radioflash signal from a nuclear explosion to obtain the gamma-ray time history was proposed by E. D. Dracott of the Atomic Weapons Research Establishment. A simplified development of an elaboration by B. R. Suydam has been programmed for small calculators in a form suitable for interim field analysis of such data. The development of the program is contained in the report

  11. Geomagnetic Field During a Reversal

    Science.gov (United States)

    Heirtzler, J. R.

    2003-01-01

    It has frequently been suggested that only the geomagnetic dipole, rather than higher order poles, reverse during a geomagnetic field reversal. Under this assumption the geomagnetic field strength has been calculated for the surface of the Earth for various steps of the reversal process. Even without an eminent a reversal of the field, extrapolation of the present secular change (although problematic) shows that the field strength may become zero in some geographic areas within a few hundred years.

  12. Total electron content responses to HILDCAAs and geomagnetic storms over South America

    Science.gov (United States)

    Mara de Siqueira Negreti, Patricia; Rodrigues de Paula, Eurico; Nicoli Candido, Claudia Maria

    2017-12-01

    Total electron content (TEC) is extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. This subject is of greatest importance for space weather applications. Under disturbed conditions the two main sources of electric fields, which are responsible for changes in the plasma drifts and for current perturbations, are the short-lived prompt penetration electric fields (PPEFs) and the longer-lasting ionospheric disturbance dynamo (DD) electric fields. Both mechanisms modulate the TEC around the globe and the equatorial ionization anomaly (EIA) at low latitudes. In this work we computed vertical absolute TEC over the low latitude of South America. The analysis was performed considering HILDCAA (high-intensity, long-duration, continuous auroral electrojet (AE) activity) events and geomagnetic storms. The characteristics of storm-time TEC and HILDCAA-associated TEC will be presented and discussed. For both case studies presented in this work (March and August 2013) the HILDCAA event follows a geomagnetic storm, and then a global scenario of geomagnetic disturbances will be discussed. Solar wind parameters, geomagnetic indices, O / N2 ratios retrieved by GUVI instrument onboard the TIMED satellite and TEC observations will be analyzed and discussed. Data from the RBMC/IBGE (Brazil) and IGS GNSS networks were used to calculate TEC over South America. We show that a HILDCAA event may generate larger TEC differences compared to the TEC observed during the main phase of the precedent geomagnetic storm; thus, a HILDCAA event may be more effective for ionospheric response in comparison to moderate geomagnetic storms, considering the seasonal conditions. During the August HILDCAA event, TEC enhancements from ˜ 25 to 80 % (compared to quiet time) were observed. These enhancements are much higher than the quiet-time variability observed in the ionosphere. We show that ionosphere is quite sensitive to solar wind forcing and

  13. Total electron content responses to HILDCAAs and geomagnetic storms over South America

    Directory of Open Access Journals (Sweden)

    P. M. de Siqueira Negreti

    2017-12-01

    Full Text Available Total electron content (TEC is extensively used to monitor the ionospheric behavior under geomagnetically quiet and disturbed conditions. This subject is of greatest importance for space weather applications. Under disturbed conditions the two main sources of electric fields, which are responsible for changes in the plasma drifts and for current perturbations, are the short-lived prompt penetration electric fields (PPEFs and the longer-lasting ionospheric disturbance dynamo (DD electric fields. Both mechanisms modulate the TEC around the globe and the equatorial ionization anomaly (EIA at low latitudes. In this work we computed vertical absolute TEC over the low latitude of South America. The analysis was performed considering HILDCAA (high-intensity, long-duration, continuous auroral electrojet (AE activity events and geomagnetic storms. The characteristics of storm-time TEC and HILDCAA-associated TEC will be presented and discussed. For both case studies presented in this work (March and August 2013 the HILDCAA event follows a geomagnetic storm, and then a global scenario of geomagnetic disturbances will be discussed. Solar wind parameters, geomagnetic indices, O ∕ N2 ratios retrieved by GUVI instrument onboard the TIMED satellite and TEC observations will be analyzed and discussed. Data from the RBMC/IBGE (Brazil and IGS GNSS networks were used to calculate TEC over South America. We show that a HILDCAA event may generate larger TEC differences compared to the TEC observed during the main phase of the precedent geomagnetic storm; thus, a HILDCAA event may be more effective for ionospheric response in comparison to moderate geomagnetic storms, considering the seasonal conditions. During the August HILDCAA event, TEC enhancements from  ∼  25 to 80 % (compared to quiet time were observed. These enhancements are much higher than the quiet-time variability observed in the ionosphere. We show that ionosphere is quite sensitive to

  14. Studying the Relationship between High-Latitude Geomagnetic Activity and Parameters of Interplanetary Magnetic Clouds with the Use of Artificial Neural Networks

    Science.gov (United States)

    Barkhatov, N. A.; Revunov, S. E.; Vorobjev, V. G.; Yagodkina, O. I.

    2018-03-01

    The cause-and-effect relations of the dynamics of high-latitude geomagnetic activity (in terms of the AL index) and the type of the magnetic cloud of the solar wind are studied with the use of artificial neural networks. A recurrent neural network model has been created based on the search for the optimal physically coupled input and output parameters characterizing the action of a plasma flux belonging to a certain magnetic cloud type on the magnetosphere. It has been shown that, with IMF components as input parameters of neural networks with allowance for a 90-min prehistory, it is possible to retrieve the AL sequence with an accuracy to 80%. The successful retrieval of the AL dynamics by the used data indicates the presence of a close nonlinear connection of the AL index with cloud parameters. The created neural network models can be applied with high efficiency to retrieve the AL index, both in periods of isolated magnetospheric substorms and in periods of the interaction between the Earth's magnetosphere and magnetic clouds of different types. The developed model of AL index retrieval can be used to detect magnetic clouds.

  15. Risk Analysis and Forecast Service for Geomagnetically Induced Currents in Europe

    Science.gov (United States)

    Wik, Magnus; Pirjola, Risto; Viljanen, Ari; Lundstedt, Henrik

    Geomagnetically induced currents (GIC), occurring during magnetic storms, pose a widespread natural disaster risk to the reliable operation of electric power transmission grids, oil and gas pipelines, telecommunication cables and railway systems. The solar magnetic activity is the cause of GIC. Solar coronal holes can cause recurrent inter-vals of raised geomagnetic activity, and coronal mass ejections (CME) at the Sun, sometimes producing very high speed plasma clouds with enhanced magnetic fields and particle densities, can cause the strongest geomagnetic storms. When the solar wind interacts with the geomag-netic field, energy is transferred to the magnetosphere, driving strong currents in the ionosphere. When these currents change in time a geoelectric field is induced at the surface of the Earth and in the ground. Finally, this field drives GIC in the ground and in any technological conductor systems. The worst consequence of a severe magnetic storm within a power grid is a complete blackout, as happened in the province of Québec, Canada, in March 1989, and in the city of Malmü, Sweden, in October 2003. Gas and oil pipelines are not regarded as vulnerable to the immediate impact of GIC, but the corrosion rate of buried steel pipes can increase due to GIC, which may thus shorten the lifetime of a pipe. European Risk from Geomagnetically Induced Currents (EURISGIC) is an EU project, that, if approved, will produce the first European-wide real-time prototype forecast service of GIC in power systems, based on in-situ solar wind observations and comprehensive simulations of the Earth's magnetosphere. This project focuses on high-voltage power transmission networks, which are probably currently the most susceptible to GIC effects. Geomagnetic storms cover large geographical regions, at times the whole globe. Consequently, power networks are rightly described as being European critical infrastructures whose disruption or destruction could have a significant impact

  16. Geomagnetic Reversals during the Phanerozoic.

    Science.gov (United States)

    McElhinny, M W

    1971-04-09

    An antalysis of worldwide paleomagnetic measurements suggests a periodicity of 350 x 10(6) years in the polarity of the geomagnetic field. During the Mesozoic it is predominantly normal, whereas during the Upper Paleozoic it is predominantly reversed. Although geomagnetic reversals occur at different rates throughout the Phanerozoic, there appeaars to be no clear correlation between biological evolutionary rates and reversal frequency.

  17. Time variations in geomagnetic intensity

    Science.gov (United States)

    Valet, Jean-Pierre

    2003-03-01

    After many years spent by paleomagnetists studying the directional behavior of the Earth's magnetic field at all possible timescales, detailed measurements of field intensity are now needed to document the variations of the entire vector and to analyze the time evolution of the field components. A significant step has been achieved by combining intensity records derived from archeological materials and from lava flows in order to extract the global field changes over the past 12 kyr. A second significant step was due to the emergence of coherent records of relative paleointensity using the remanent magnetization of sediments to retrace the evolution of the dipole field. A third step was the juxtaposition of these signals with those derived from cosmogenic isotopes. Contemporaneous with the acquisition of records, new techniques have been developed to constrain the geomagnetic origin of the signals. Much activity has also been devoted to improving the quality of determinations of absolute paleointensity from volcanic rocks with new materials, proper selection of samples, and investigations of complex changes in magnetization during laboratory experiments. Altogether these developments brought us from a situation where the field changes were restricted to the past 40 kyr to the emergence of a coherent picture of the changes in the geomagnetic dipole moment for at least the past 1 Myr. On longer timescales the field variability and its average behavior is relatively well documented for the past 400 Myr. Section 3 gives a summary of most methods and techniques that are presently used to track the field intensity changes in the past. In each case, current limits and potential promises are discussed. The section 4 describes the field variations measured so far over various timescales covered by the archeomagnetic and the paleomagnetic records. Preference has always been given to composite records and databases in order to extract and discuss major and global geomagnetic

  18. Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch

    Directory of Open Access Journals (Sweden)

    Mario Brkić

    2013-12-01

    Full Text Available After more than half a century, scientific book Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch describes the recent geomagnetic field on Croatian territory. A review of research in the past decade as well as the original solutions makes the book a document of contribution to geodesy and geomagnetism in Croatia.The book’s introduction gives an overview of two centuries of history and the strategic, security, economic and scientific significance of knowing the geomagnetic field on the Croatian territory. All the activities related to the updating of the geomagnetic information, which took place in the last decade, signified a big step toward the countries where geomagnetic survey is a mature scientific and technical discipline, and a scientific contribution to understanding of the nature of the Earth's magnetism.The declination, inclination and total intensity maps (along with the normal annual changes for the epoch 2009.5 are given in the Appendix. The book Basic Geomagnetic Network of the Republic of Croatia 2004 – 2012, with Geomagnetic Field Maps for 2009.5 epoch (ISBN 978-953-293-521-9 is published by the State Geodetic Administration of the Republic of Croatia. Beside editor in chief, M. Brkić, the authors are: E. Vujić, D. Šugar, E. Jungwirth, D. Markovinović, M. Rezo, M. Pavasović, O. Bjelotomić, M. Šljivarić, M. Varga and V. Poslončec-Petrić. The book contains 48 pages and 3 maps, and is published in 200 copies. CIP record is available in digital catalogue of the National and University Library in Zagreb under number 861937.

  19. Re-Evaluation of Geomagnetic Field Observation Data at Syowa Station, Antarctica

    Directory of Open Access Journals (Sweden)

    K Takahashi

    2013-05-01

    Full Text Available The Japanese Antarctic Research Expedition has conducted geomagnetic observations at Syowa Station, Antarctica, since 1966. Geomagnetic variation data measured with a fluxgate magnetometer are not absolute but are relative to a baseline and show drift. To enhance the importance of the geomagnetic data at Syowa Station, therefore, it is necessary to correct the continuous variation data by using absolute baseline values acquired by a magnetic theodolite and proton magnetometer. However, the database of baseline values contains outliers. We detected outliers in the database and then converted the geomagnetic variation data to absolute values by using the reliable baseline values.

  20. The influence of solar active region evolution on solar wind streams, coronal hole boundaries and geomagnetic storms

    International Nuclear Information System (INIS)

    Gold, R.E.; Dodson-Prince, H.W.; Hedeman, E.R.; Roelof, E.C.

    1982-01-01

    We have studied solar and interplanetary data by identification of the heliographic longitudes of the coronal source regions of high speed solar wind streams and by mapping the velocities measured near earth back to the sun using the approximation of constant radial velocity. Interplay of active regions and solar wind were studied

  1. The influence of solar active region evolution on solar wind streams, coronal hole boundaries and geomagnetic storms

    Science.gov (United States)

    Gold, R. E.; Dodson-Prince, H. W.; Hedeman, E. R.; Roelof, E. C.

    1982-01-01

    Solar and interplanetary data are examined, taking into account the identification of the heliographic longitudes of the coronal source regions of high speed solar wind (SW) streams by Nolte and Roelof (1973). Nolte and Roelof have 'mapped' the velocities measured near earth back to the sun using the approximation of constant radial velocity. The 'Carrington carpet' for rotations 1597-1616 is shown in a graph. Coronal sources of high speed streams appear in the form of solid black areas. The contours of the stream sources are laid on 'evolutionary charts' of solar active region histories for the Southern and Northern Hemispheres. Questions regarding the interplay of active regions and solar wind are investigated, giving attention to developments during the years 1973, 1974, and 1975.

  2. The driving mechanisms of particle precipitation during the moderate geomagnetic storm of 7 January 2005

    Directory of Open Access Journals (Sweden)

    N. Longden

    2007-10-01

    Full Text Available The arrival of an interplanetary coronal mass ejection (ICME triggered a sudden storm commencement (SSC at ~09:22 UT on the 7 January 2005. The ICME followed a quiet period in the solar wind and interplanetary magnetic field (IMF. We present global scale observations of energetic electron precipitation during the moderate geomagnetic storm driven by the ICME. Energetic electron precipitation is inferred from increases in cosmic noise absorption (CNA recorded by stations in the Global Riometer Array (GLORIA. No evidence of CNA was observed during the first four hours of passage of the ICME or following the sudden commencement (SC of the storm. This is consistent with the findings of Osepian and Kirkwood (2004 that SCs will only trigger precipitation during periods of geomagnetic activity or when the magnetic perturbation in the magnetosphere is substantial. CNA was only observed following enhanced coupling between the IMF and the magnetosphere, resulting from southward oriented IMF. Precipitation was observed due to substorm activity, as a result of the initial injection and particles drifting from the injection region. During the recovery phase of the storm, when substorm activity diminished, precipitation due to density driven increases in the solar wind dynamic pressure (Pdyn were identified. A number of increases in Pdyn were shown to drive sudden impulses (SIs in the geomagnetic field. While many of these SIs appear coincident with CNA, SIs without CNA were also observed. During this period, the threshold of geomagnetic activity required for SC driven precipitation was exceeded. This implies that solar wind density driven SIs occurring during storm recovery can drive a different response in particle precipitation to typical SCs.

  3. (Tele)Connectivity in climate variability at different spatial/temporal scales in relation to solar and geomagnetic activity

    Czech Academy of Sciences Publication Activity Database

    Paluš, Milan; Hartman, David; Vejmelka, Martin; Novotná, Dagmar

    2011-01-01

    Roč. 13, - (2011), s. 9579 ISSN 1607-7962. [European Geosciences Union General Assembly 2011. 03.04.2011-08.04.2011, Vienna] R&D Projects: GA AV ČR IAA300420805 Institutional research plan: CEZ:AV0Z10300504; CEZ:AV0Z30420517 Keywords : climate variability * phase coherence * synchronization * North Atlantic Oscillation * solar activity Subject RIV: BB - Applied Statistics, Operational Research

  4. On the scaling features of high-latitude geomagnetic field fluctuations during a large geomagnetic storm

    Science.gov (United States)

    De Michelis, Paola; Federica Marcucci, Maria; Consolini, Giuseppe

    2015-04-01

    Recently we have investigated the spatial distribution of the scaling features of short-time scale magnetic field fluctuations using measurements from several ground-based geomagnetic observatories distributed in the northern hemisphere. We have found that the scaling features of fluctuations of the horizontal magnetic field component at time scales below 100 minutes are correlated with the geomagnetic activity level and with changes in the currents flowing in the ionosphere. Here, we present a detailed analysis of the dynamical changes of the magnetic field scaling features as a function of the geomagnetic activity level during the well-known large geomagnetic storm occurred on July, 15, 2000 (the Bastille event). The observed dynamical changes are discussed in relationship with the changes of the overall ionospheric polar convection and potential structure as reconstructed using SuperDARN data. This work is supported by the Italian National Program for Antarctic Research (PNRA) - Research Project 2013/AC3.08 and by the European Community's Seventh Framework Programme ([FP7/2007-2013]) under Grant no. 313038/STORM and

  5. Zonal wind observations during a geomagnetic storm

    Science.gov (United States)

    Miller, N. J.; Spencer, N. W.

    1986-01-01

    In situ measurements taken by the Wind and Temperature Spectrometer (WATS) onboard the Dynamics Explorer 2 spacecraft during a geomagnetic storm display zonal wind velocities that are reduced in the corotational direction as the storm intensifies. The data were taken within the altitudes 275 to 475 km in the dusk local time sector equatorward of the auroral region. Characteristic variations in the value of the Dst index of horizontal geomagnetic field strength are used to monitor the storm evolution. The detected global rise in atmospheric gas temperature indicates the development of thermospheric heating. Concurrent with that heating, reductions in corotational wind velocities were measured equatorward of the auroral region. Just after the sudden commencement, while thermospheric heating is intense in both hemispheres, eastward wind velocities in the northern hemisphere show reductions ranging from 500 m/s over high latitudes to 30 m/s over the geomagnetic equator. After 10 hours storm time, while northern thermospheric heating is diminishing, wind velocity reductions, distinct from those initially observed, begin to develop over southern latitudes. In the latter case, velocity reductions range from 300 m/s over the highest southern latitudes to 150 m/s over the geomagnetic equator and extend into the Northern Hemisphere. The observations highlight the interhemispheric asymmetry in the development of storm effects detected as enhanced gas temperatures and reduced eastward wind velocities. Zonal wind reductions over high latitudes can be attributed to the storm induced equatorward spread of westward polar cap plasma convection and the resulting plasma-neutral collisions. However, those collisions are less significant over low latitudes; so zonal wind reductions over low latitudes must be attributed to an equatorward extension of a thermospheric circulation pattern disrupted by high latitude collisions between neutrals transported via eastward winds and ions

  6. Electric field in the magnetotail depending on the geomagnetic activity level and intensity Esub(y) in the solar wind

    International Nuclear Information System (INIS)

    Pudovkin, M.I.; Osipov, V.V.; Shukhtina, M.A.; Zajtseva, S.A.; AN SSSR, Vladivostok. Dal'nevostochnyh Nauchnyj Tsentr)

    1982-01-01

    The value of the large-scale electric field in the near magnetotail on AE-index variations delay in relation to interplanetary electric field variations is estimated. It is obtained that the electric field value in a tail increases with magnetic activity level. The solar wind electric field under strong magnetic disturbance penetrates into the magnetosphere practically without weakening and is essentially weakened in magneto-quit conditions. Calculated values of the electric field magnitude in the magnetotail (0.01-1mBm) are in agreement with those obtained earlier [ru

  7. Solar wind velocity and geomagnetic moment variations

    International Nuclear Information System (INIS)

    Kalinin, Yu.D.; Rozanova, T.S.

    1982-01-01

    The mean year values of the solar wind velocity have been calculated from the mean-year values of a geomagnetic activity index am according to the Svalgard equation of regression for the pe-- riod from 1930 to 1960. For the same years the values of the geomagnetic moment M and separately of its ''inner'' (causes of which'' are inside the Earth) and ''external'' (causes of which are outside the Earth) parts have been calculated from the mean year data of 12 magnetic observatories. The proof of the presence of the 11-year variation in the moment M has been obtained. It is concluded that the 11-year variations in M result from the variations of the solar wind velocity

  8. Geomagnetic, ionospheric and cosmic ray variations around the passages of different magnetic clouds

    International Nuclear Information System (INIS)

    Maercz, F.

    1992-01-01

    Thirty-four interplanetary magnetic clouds have been divided into two groups on the basis of Wilson's (J.geophys. Res. 95, 215, 1990) classification: NS clouds (whose B z near cloud onset at Earth is directed northward, and soon after B z is turning southward) and SN clouds (those with an opposite behaviour with respect to B z ). Using the days of cloud onsets as key days, geomagnetic, ionospheric and cosmic ray data have been analysed by the superposed epoch analysis method for passages of both NS and SN clouds. On the basis of the daily ΣK p values, geomagnetic activity is found to suddenly increase in the vicinity of both types of cloud passages. Afterwards, the variation shown by the geomagnetic indices is found to differ for NS clouds in comparison with SN clouds. Namely, on average the recovery to a normal activity level is much slower for NS clouds. Similarly, the enhancements in the ionospheric absorption of radio waves (the so-called ''after-effects'') are found to show different signatures according to cloud type, an interpretation also valid for variations in cosmic ray intensity. The latter results are based on analyses of neutron monitor counts observed at two stations (Apatity: 67 N; and Moscow: 55 o N). (author)

  9. The interplanetary causes of geomagnetic activity during the 7–17 March 2012 interval: a CAWSES II overview

    Directory of Open Access Journals (Sweden)

    Tsurutani Bruce T.

    2014-01-01

    Full Text Available This overview paper presents/discusses the major solar, interplanetary, magnetospheric, and ionospheric features of the CAWSES II interval of study: 7–17 March 2012. Magnetic storms occurred on 7, 9, 12, and 15 March with peak SYM-H intensities of −98 nT, −148 nT, −75 nT (pressure corrected, and −79 nT, respectively. These are called the S1, S2, S3, and S4 events. Although three of the storm main phases (S1, S3, and S4 were caused by IMF Bsouth sheath fields and the S2 event was associated with a magnetic cloud (MC, the detailed scenario for all four storms were different. Two interplanetary features with unusually high temperatures and intense and quiet magnetic fields were identified located antisunward of the MCs (S2 and S3. These features are signatures of either coronal loops or coronal sheaths. A high speed stream (HSS followed the S4 event where the presumably southward IMF Bz components of the Alfvén waves extended the storm “recovery phase” by several days. The ICME-associated shocks were particularly intense. The fast forward shock for the S2 event had a magnetosonic Mach number of ~9.4, the largest in recorded history. All of the shocks associated with the ICMEs created sudden impulses (SI+s at Earth. The shocks preceding the S2 and S3 magnetic storms caused unusually high SI+ intensities of ~60 and 68 nT, respectively. Many further studies on various facets of this active interval are suggested for CAWSES II researchers and other interested parties.

  10. Regional 3-D Modeling of Ground Geoelectric Field for the Northeast United States due to Realistic Geomagnetic Disturbances

    Science.gov (United States)

    Ivannikova, E.; Kruglyakov, M.; Kuvshinov, A. V.; Rastaetter, L.; Pulkkinen, A. A.; Ngwira, C. M.

    2017-12-01

    During extreme space weather events electric currents in the Earth's magnetosphere and ionosphere experience large variations, which leads to dramatic intensification of the fluctuating magnetic field at the surface of the Earth. According to Faraday's law of induction, the fluctuating geomagnetic field in turn induces electric field that generates harmful currents (so-called "geomagnetically induced currents"; GICs) in grounded technological systems. Understanding (via modeling) of the spatio-temporal evolution of the geoelectric field during enhanced geomagnetic activity is a key consideration in estimating the hazard to technological systems from space weather. We present the results of ground geoelectric field modeling for the Northeast United States, which is performed with the use of our novel numerical tool based on integral equation approach. The tool exploits realistic regional three-dimensional (3-D) models of the Earth's electrical conductivity and realistic global models of the spatio-temporal evolution of the magnetospheric and ionospheric current systems responsible for geomagnetic disturbances. We also explore in detail the manifestation of the coastal effect (anomalous intensification of the geoelectric field near the coasts) in this region.

  11. The Geomagnetic Control Concept of The Ionospheric Long- Term Trends

    Science.gov (United States)

    Mikhailov, A. V.

    The geomagnetic control concept has been developed to explain long-term trends of the electron concentration in the F2 and E ionospheric regions. Periods with negative and positive foF2, hmF2 and foE trends correspond to the periods of increasing or decreasing geomagnetic activity with the turning points around the end of 1950s, 1960s, and 1980s where trends change their signs. Strong latitudinal and diurnal variations revealed for the foF2 and hmF2 trends can be explained by neutral composition, temperature and thermospheric wind changes. Particle precipitation is important in the auroral zone. The newly proposed concept proceeds from a natural origin of the F2-layer trends rather than an artificial one related to the greenhouse effect. Using the proposed method a very long-term foF2 and foE trends related with general increase of geomagnetic activity in the 20th century has been revealed for the first time. The firstly revealed relationship of the foE trends with geomagnetic activity is due to nitric oxide variations at the E-region heights. This "natural" relationship of the foE trends with geomagnetic activity breaks down around 1970 on many stations presumably due to chemical polution of the upper atmosphere. The increasing rate of rocket and satellite launchings in the late 1960s is considered as a reason.

  12. Unexpected Southern Hemisphere ionospheric response to geomagnetic storm of 15 August 2015

    Science.gov (United States)

    Edemskiy, Ilya; Lastovicka, Jan; Buresova, Dalia; Bosco Habarulema, John; Nepomnyashchikh, Ivan

    2018-01-01

    Geomagnetic storms are the most pronounced phenomenon of space weather. When studying ionospheric response to a storm of 15 August 2015, an unexpected phenomenon was observed at higher middle latitudes of the Southern Hemisphere. This phenomenon was a localized total electron content (TEC) enhancement (LTE) in the form of two separated plumes, which peaked southward of South Africa. The plumes were first observed at 05:00 UT near the southwestern coast of Australia. The southern plume was associated with local time slightly after noontime (1-2 h after local noon). The plumes moved with the Sun. They peaked near 13:00 UT southward of South Africa. The southern plume kept constant geomagnetic latitude (63-64° S); it persisted for about 10 h, whereas the northern plume persisted for about 2 h more. Both plumes disappeared over the South Atlantic Ocean. No similar LTE event was observed during the prolonged solar activity minimum period of 2006-2009. In 2012-2016 we detected altogether 26 LTEs and all of them were associated with the southward excursion of Bz. The negative Bz excursion is a necessary but not sufficient condition for the LTE occurrence as during some geomagnetic storms associated with negative Bz excursions the LTE events did not appear.

  13. Unexpected Southern Hemisphere ionospheric response to geomagnetic storm of 15 August 2015

    Directory of Open Access Journals (Sweden)

    I. Edemskiy

    2018-01-01

    Full Text Available Geomagnetic storms are the most pronounced phenomenon of space weather. When studying ionospheric response to a storm of 15 August 2015, an unexpected phenomenon was observed at higher middle latitudes of the Southern Hemisphere. This phenomenon was a localized total electron content (TEC enhancement (LTE in the form of two separated plumes, which peaked southward of South Africa. The plumes were first observed at 05:00 UT near the southwestern coast of Australia. The southern plume was associated with local time slightly after noontime (1–2 h after local noon. The plumes moved with the Sun. They peaked near 13:00 UT southward of South Africa. The southern plume kept constant geomagnetic latitude (63–64° S; it persisted for about 10 h, whereas the northern plume persisted for about 2 h more. Both plumes disappeared over the South Atlantic Ocean. No similar LTE event was observed during the prolonged solar activity minimum period of 2006–2009. In 2012–2016 we detected altogether 26 LTEs and all of them were associated with the southward excursion of Bz. The negative Bz excursion is a necessary but not sufficient condition for the LTE occurrence as during some geomagnetic storms associated with negative Bz excursions the LTE events did not appear.

  14. Method for enhancing amidohydrolase activity of fatty acid amide hydrolase

    Science.gov (United States)

    John, George; Nagarajan, Subbiah; Chapman, Kent; Faure, Lionel; Koulen, Peter

    2016-10-25

    A method for enhancing amidohydrolase activity of Fatty Acid Amide Hydrolase (FAAH) is disclosed. The method comprising administering a phenoxyacylethanolamide that causes the enhanced activity. The enhanced activity can have numerous effects on biological organisms including, for example, enhancing the growth of certain seedlings. The subject matter disclosed herein relates to enhancers of amidohydrolase activity.

  15. The solar and interplanetary causes of the recent minimum in geomagnetic activity (MGA23: a combination of midlatitude small coronal holes, low IMF BZ variances, low solar wind speeds and low solar magnetic fields

    Directory of Open Access Journals (Sweden)

    B. T. Tsurutani

    2011-05-01

    Full Text Available Minima in geomagnetic activity (MGA at Earth at the ends of SC23 and SC22 have been identified. The two MGAs (called MGA23 and MGA22, respectively were present in 2009 and 1997, delayed from the sunspot number minima in 2008 and 1996 by ~1/2–1 years. Part of the solar and interplanetary causes of the MGAs were exceptionally low solar (and thus low interplanetary magnetic fields. Another important factor in MGA23 was the disappearance of equatorial and low latitude coronal holes and the appearance of midlatitude coronal holes. The location of the holes relative to the ecliptic plane led to low solar wind speeds and low IMF (Bz variances (σBz2 and normalized variances (σBz2/B02 at Earth, with concomitant reduced solar wind-magnetospheric energy coupling. One result was the lowest ap indices in the history of ap recording. The results presented here are used to comment on the possible solar and interplanetary causes of the low geomagnetic activity that occurred during the Maunder Minimum.

  16. Magnetic local time dependence of geomagnetic disturbances contributing to the AU and AL indices

    DEFF Research Database (Denmark)

    Tomita, S; Nose´, M; Iyemori, T

    2010-01-01

    activity in the auroral zone. In the present study, we examine magnetic local time (MLT) dependence of geomagnetic field variations contributing to the AU and AL indices. We use 1-min geomagnetic field data obtained in 2003. It is found that both AU and AL indices have two ranges of MLT (AU: 15:00-22:00MLT...

  17. Global Ultra-Low-Frequency Geomagnetic Pulsations Associated with the March 24, 1991 Geomagnetic Storm

    Directory of Open Access Journals (Sweden)

    Nan-Wei Chen Jann-Yenq Liu

    2008-01-01

    Full Text Available On 24 March 1991, global ultra-low-frequency (ULF pulsations (1.1 - 3.3 mHz observed in the magnetosphere as well as on the ground were studied via analyzing magnetic field data obtained from a global network, comprising ground-based observatories and geosynchronous satellites. In the magnetosphere, the compressional and transverse components of the magnetic fields recorded at two satellites, GOES 6 and GOES 7, showed dominant fluctuations when they were in the vicinity of the noon sector, whereas the transverse fluctuations became dominant when they were at the dawn side. Similarly, on the ground, the H and D components had major fluctuations along with an increase in amplitude from low to high geomagnetic latitudes. In addition, the amplitude of the ULF pulsation was enhanced at the dawn and dusk sides. The geomagnetic pulsations propagated anti-sunward and were of counterclockwise and clockwise elliptical polarizations at the dawn and dusk sides respectively. The counterclockwise elliptical polarization reversed to a clockwise elliptical polarization at geomagnetic local noon and linear polarization was observed during the reversal. It appears that the analysis of the global network data not only provided us with a study of the characteristics of the waves in the magnetosphere and on the ground but also provided us with correlations between the geosynchronous and ground observations, which should be essential to the determination of possible mechanisms of this storm-related wave event.

  18. Effect of geomagnetic storms on VHF scintillations observed at low latitude

    Science.gov (United States)

    Singh, S. B.; Patel, Kalpana; Singh, A. K.

    2018-06-01

    A geomagnetic storm affects the dynamics and composition of the ionosphere and also offers an excellent opportunity to study the plasma dynamics. In the present study, we have used the VHF scintillations data recorded at low latitude Indian station Varanasi (Geomag. latitude = 14^{°}55^' }N, long. = 154^{°}E) which is radiated at 250 MHz from geostationary satellite UFO-02 during the period 2011-2012 to investigate the effects of geomagnetic storms on VHF scintillation. Various geomagnetic and solar indices such as Dst index, Kp index, IMF Bz and solar wind velocity (Vx) are used to describe the geomagnetic field variation observed during geomagnetic storm periods. These indices are very helpful to find out the proper investigation and possible interrelation between geomagnetic storms and observed VHF scintillation. The pre-midnight scintillation is sometimes observed when the main phase of geomagnetic storm corresponds to the pre-midnight period. It is observed that for geomagnetic storms for which the recovery phase starts post-midnight, the probability of occurrence of irregularities is enhanced during this time and extends to early morning hours.

  19. Comment on geomagnetic activity associated with earth passage of interplanetary shock disturbances and coronal mass ejections by J.T. Gosling, D.J. McComas, J.L. Phillips, and S.J. Bame

    International Nuclear Information System (INIS)

    Tsurutani, B.T.; Gonzalez, W.D.

    1993-01-01

    Gosling et al. have presented a very nice set of statistical data on solar wind driver gases (CMEs), interplanetary shocks, solar wind velocities, magnetic field magnitudes and B z values, and geomagnetic activity (Kp). The statistics are quite nice and similar to our own. The authors have no questions or comments concerning these. The authors note that Gosling et al. have one conclusion that is substantially different than prior work, however. In the last sentence of their abstract, they state, open-quotes The initial speed of a CME close to the Sun appears to be the most crucial factor in determining if an earthward directed event will be effective in exciting a large geomagnetic disturbance.close quotes This is an unusual claim and goes quite contrary to prior perceptions of the interplanetary cause of magnetic storms, big and small. If this point is indeed correct it will be a big revelation to magnetospheric researchers. However, in looking at their paper in detail, the authors feel the statistical data that they presented do not support this claim. In this comment the authors will try to help clarify this issue and attempt to bring the Gosling et al. statistics and prior results into accord. 28 refs

  20. The Ranges Of Subauroral Geomagnetic Field Elements | Rabiu ...

    African Journals Online (AJOL)

    Nigeria Journal of Pure and Applied Physics ... An anomaly in seasonal response of range at high solar activity is observed on disturbed condition. ... apart from the anomaly - maintain the order e>j>d of seasonal variation which is in agreement with the popular equinoctial maximum observed in geomagnetic activity.

  1. Intermittency and multifractional Brownian character of geomagnetic time series

    Directory of Open Access Journals (Sweden)

    G. Consolini

    2013-07-01

    Full Text Available The Earth's magnetosphere exhibits a complex behavior in response to the solar wind conditions. This behavior, which is described in terms of mutifractional Brownian motions, could be the consequence of the occurrence of dynamical phase transitions. On the other hand, it has been shown that the dynamics of the geomagnetic signals is also characterized by intermittency at the smallest temporal scales. Here, we focus on the existence of a possible relationship in the geomagnetic time series between the multifractional Brownian motion character and the occurrence of intermittency. In detail, we investigate the multifractional nature of two long time series of the horizontal intensity of the Earth's magnetic field as measured at L'Aquila Geomagnetic Observatory during two years (2001 and 2008, which correspond to different conditions of solar activity. We propose a possible double origin of the intermittent character of the small-scale magnetic field fluctuations, which is related to both the multifractional nature of the geomagnetic field and the intermittent character of the disturbance level. Our results suggest a more complex nature of the geomagnetic response to solar wind changes than previously thought.

  2. Solar energetic particle flux enhancement as a predictor of geomagnetic activity in a neural network-based model

    Czech Academy of Sciences Publication Activity Database

    Valach, F.; Revallo, M.; Bochníček, Josef; Hejda, Pavel

    2009-01-01

    Roč. 7, April (2009), S04004/1-S04004/7 ISSN 1542-7390 R&D Projects: GA AV ČR(CZ) IAA300120608; GA AV ČR 1QS300120506 Institutional research plan: CEZ:AV0Z30120515 Keywords : neural networks * coronal mass ejections * energetic particles * flares * radio emissions * magnetic storms Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.845, year: 2009

  3. Fluxgate Magnetometer Array for Geomagnetic Abnormal Phenomena Tracking

    Directory of Open Access Journals (Sweden)

    Xiaomei Wang

    2011-06-01

    Full Text Available The objective of this project is to develop a flexible observation mode for a geomagnetic abnormal phenomena tracking system. The instrument, based on ring core fluxgate magnetometer technology, improves the field environment performance. Using wireless technology provides on-the-spot mobile networking for the observational data, with efficient access to the earthquake precursor observation network. It provides a powerful detection method for earthquake short-term prediction through installation of a low-noise fluxgate magnetometer array, intensely observing the phenomenon of geomagnetic disturbances and abnormal low-frequency electromagnetic signals in different latitudes, then carrying out observational data processing and exploring the relationship between earthquake activity and geomagnetic field changes.

  4. Operations of the World Data Centre for Geomagnetism, Edinburgh

    Directory of Open Access Journals (Sweden)

    S J Reay

    2013-01-01

    Full Text Available The British Geological Survey has operated a World Data Centre for Geomagnetism since 1966. Geomagnetic time-series data from around 280 observatories worldwide at a number of time resolutions are held along with various magnetic survey, model, and activity index data. The operation of this data centre provides a valuable resource for the geomagnetic research community. The operation of the WDC and details of the range of data held are presented. The quality control procedures that are applied to incoming data are described as is the work to collaborate with other data centres to distribute and improve the overall consistency of data held worldwide. The development of standards for metadata associated with datasets is demonstrated, and current efforts to digitally preserve the BGS analogue holdings of magnetograms and observatory yearbooks are described.

  5. Anomalous changes of vertical geomagnetic field in Kamchatka

    Directory of Open Access Journals (Sweden)

    Moroz Yuriy

    2016-01-01

    Full Text Available Secular variations of the vertical geomagnetic field at Paratunka (Kamchatka, Kakioka (Honshu, Mamambetsu (Hokkaido and Patrony (Irkutsk are considered from 1968 to 2014. Comparative analysis of secular variations showed that from 1968 to 2001, similar variations with the intensity of first hundreds on nT are obvious at four observatories. For the following period from 2001 to 2014, the secular variation at Paratunka observatory differs from other observatories. This disagreement of the secular geomagnetic variation at Paratunka observatory is timed to the increase of seismicity at the depth of 400-700 km in South Kamchatka region. It is suggested that in the result of increase of the seismicity in the region of transition from the upper to lower mantle, physical and chemical processes became more active. That caused formation of a large geo-electrical inhomogeneity which affected the behavior of the vertical component of geomagnetic field.

  6. Mantle superplumes induce geomagnetic superchrons

    Directory of Open Access Journals (Sweden)

    Peter eOlson

    2015-07-01

    Full Text Available We use polarity reversal systematics from numerical dynamos to quantify the hypothesis that the modulation of geomagnetic reversal frequency, including geomagnetic superchrons, results from changes in core heat flux related to growth and collapse of lower mantle superplumes. We parameterize the reversal frequency sensitivity from numerical dynamos in terms of average core heat flux normalized by the difference between the present-day core heat flux and the core heat flux at geomagnetic superchron onset. A low-order polynomial fit to the 0-300 Ma Geomagnetic Polarity Time Scale (GPTS reveals that a decrease in core heat flux relative to present-day of approximately 30% can account for the Cretaceous Normal Polarity and Kiaman Reverse Polarity Superchrons, whereas the hyper-reversing periods in the Jurassic require a core heat flux equal to or higher than present-day. Possible links between GPTS transitions, large igneous provinces (LIPs, and the two lower mantle superplumes are explored. Lower mantle superplume growth and collapse induce GPTS transitions by increasing and decreasing core heat flux, respectively. Age clusters of major LIPs postdate transitions from hyper-reversing to superchron geodynamo states by 30-60 Myr, suggesting that superchron onset may be contemporaneous with LIP-forming instabilities produced during collapses of lower mantle superplumes.

  7. New forecasting methods of the intensity and time development of geomagnetic and ionospheric storms

    International Nuclear Information System (INIS)

    Akasofu, S.I.

    1981-01-01

    The main phase of a geomagnetic storm develops differently from one storm to another. A description is given of the solar wind quantity which controls directly the development of the main phase of geomagnetic storms. The parameters involved include the solar wind speed, the magnetic field intensity, and the polar angle of the solar wind magnetic field projected onto the dawn-dusk plane. A redefinition of geomagnetic storm and auroral activity is given. It is pointed out that geomagnetic disturbances are caused by the magnetic fields of electric currents which are generated by the solar wind-magnetosphere dynamo. Attention is given to approaches for forecasting the occurrence and intensity of geomagnetic storms and ionospheric disturbances

  8. Reply to Comment on ``Effects of fast and slow solar wind on the correlations between interplanetary medium and geomagnetic activity'' by C. B. Wang and J. K. Chao

    Science.gov (United States)

    Ballatore, Paola

    2003-10-01

    The paper [2002] (the paper commented) shows that the statistical significance of the correlations between the interplanetary parameters and the geomagnetic indices (Kp or Dst) is generally less significant during the fastest solar wind. On the other hand, at these fast solar wind periods, the significance of the Kp versus Dst correlation is equal to or higher than during slower solar wind. These results, together with further observations related to substorm periods and with previously published findings, are interpreted in terms of a difference in the interplanetary-magnetospheric coupling for solar wind faster or slower than a certain threshold (identified between about 500 and 600 km/s). Specifically, it is suggested that a possible linear approximation of the geomagnetic-interplanetary coupling is more appropriate during solar wind speed (Vsw) slower than this threshold, being nonlinear processes more dominant during the fastest speeds. This reply highlights that the correlation coefficients shown by [2003] are in agreement with these findings. In addition, Wang and Chao show that the statistical significance of the difference between the correlation coefficients for Vsw ≥ 550 km/s and those for Vsw Wang and Chao is wrong. Moreover, Wang and Chao recalculate the correlations between the interplanetary parameters and the ΔDst instead of Dst; in fact they note that the time derivative of this index (not the index itself) is driven by the interplanetary medium. Here we note that on the contrary, they show that the correlation coefficients between interplanetary parameters and Dst are larger than those obtained using ΔDst and we suggest a possible interpretation in terms of nonlinearity.

  9. Can the tardigrade Hypsibius dujardini survive in the absence of the geomagnetic field?

    Directory of Open Access Journals (Sweden)

    Weronika Erdmann

    Full Text Available Earth's geomagnetic field has undergone critical changes in the past. Studies on the influence of the magnetic field on Earth's organisms are crucial for the understanding of evolution of life on Earth and astrobiological considerations. Numerous studies conducted both on plants and animals confirmed the significant influence of the geomagnetic field on the metabolism of living organisms. Water bears (Tardigrada, which are a mong the most resistant animals due to their cryptobiotic abilities, show significant resistance to a number of environmental stressors, but the influence of the geomagnetic field on their fitness has not been addressed before. In our studies, we used eutardigrade Hypsibius dujardini to analyse whether isolation from the geomagnetic field had an effect on mortality. We found that Hypsibius dujardini specimens demonstrated relatively high mortality during anhydrobiosis, also in control groups exposed to the normal geomagnetic field. Moreover, similar mortality was observed in anhydrobiotic specimens isolated from the geomagnetic field. However, a significant difference was noted between tardigrade survival and the moment of their isolation from the geomagnetic field. In particular, tardigrade mortality substantially increased in absence of a magnetic field during the process of entering anhydrobiosis and returning to active life. Our results suggest that these processes rely on complex metabolic processes that are critically influenced by the geomagnetic field.

  10. Different geomagnetic indices as an indicator for geo-effective solar storms and human physiological state

    Science.gov (United States)

    Dimitrova, Svetla

    2008-02-01

    A group of 86 healthy volunteers were examined on each working day during periods of high solar activity. Data about systolic and diastolic blood pressure, pulse pressure, heart rate and subjective psycho-physiological complaints were gathered. MANOVA was employed to check the significance of the influence of three factors on the physiological parameters. The factors were as follows: (1) geomagnetic activity estimated by daily amplitude of H-component of the local geomagnetic field, Ap- and Dst-index; (2) gender; and (3) the presence of medication. Average values of systolic, diastolic blood pressure, pulse pressure and subjective complaints of the group were found to increase significantly with geomagnetic activity increment.

  11. Mechanism of the relations between the changes of the geomagnetic field, solar corpuscular radiation, atmospheric circulation, and climate

    International Nuclear Information System (INIS)

    Bucha, Vaclav

    1980-01-01

    The correlations between geomagnetic, climatic, and meteorological phenomena were investigated with the object of demonstrating the function of the geomagnetic pole and changes of its position in controlling the climate and weather. A tentative model has been proposed to enable one to understand the causes of the generation of glacial and interglacial periods, as well as the causes which effect changes of climate (Bucha, 1976a). The analyses of various types of geomagnetic and atmospheric manifestations have disclosed certain associations. The coincidence in the occurrence of increased spectral densities with regard to geomagnetic activity and the variations of atmospheric pressure over the geomagnetic pole shows the relation between their periodicities. The results imply that the changes in the intensity of corpuscular radiation, indicated by geomagnetic activity, affect the temperature and pressure patterns over the geomagnetic pole and polar region significantly, so that a pronounced modification of the general circulation may take place, as shown schematically (Bucha, 1976b). As a result of investigating the relations between the variations of geomagnetic activity and meteorological factors a mechanism of solar-terrestrial relationships and a model of the changes of atmospheric circulation in the Northern Hemisphere are proposed; this provides a probable explanation of the causes of the fluctuation of the climate, of dry and cold periods and of differing vegetation conditions in various years in dependence on the intensity of geomagnetic activity (Bucha, 1976b, 1977a). (author)

  12. Method for enhancing amidohydrolase activity of fatty acid amide hydrolase

    Science.gov (United States)

    John, George; Nagarajan, Subbiah; Chapman, Kent; Faure, Lionel; Koulen, Peter

    2017-12-26

    A method for enhancing amidohydrolase activity of Fatty Acid Amide Hydrolase (FAAH) is disclosed. The method comprising administering a phenoxyacyl-ethanolamide that causes the enhanced activity. The enhanced activity can have numerous effects on biological organisms including, for example, enhancing the growth of certain seedlings.

  13. Possible seismogenic origin of changes in the ULF EM resonant structure observed at Teoloyucan geomagnetic station, Mexico, 1999-2001

    Directory of Open Access Journals (Sweden)

    A. Kotsarenko

    2005-01-01

    Full Text Available The evolution of the ULF resonant structure observed at Teoloyucan geomagnetic station has been provisionally studied in a possible relation with seismic activity in Mexico in the period 1999-2001. Two resonant lines were observed in the H-component (linear polarization in the frequency bands fR2=10.2–11.1 mHz and fR2=13.6–14.5 mHz, sometimes accompanied by other harmonics. The source of the observed resonances is possibly related with the geomagnetic location of the station (geomagnetic latitude λ=29.1° and its proximity to the equatorial electrojet (λ~30°. An enhancement of the carrier frequency of both resonances in the period 1 month–2 weeks was found before the strongest EQs. Also, a depression of the resonant structure just a few days before and a few days after some EQs seems to be correlated with seismic activity.

  14. Recent investigation at INPE in magnetospheric physics and geomagnetism

    International Nuclear Information System (INIS)

    Gonzales, W.D.; Trivedi, N.B.

    1984-01-01

    During recent years the following research activities related to the earth's magnetosphere have been intensified: a) studies on electric field and energy transfer from the solar wind to the magnetosphere; b) studies on high latitude magnetospheric electric fields and on their penetration into the plasmasphere; c) measurements of atmospheric-large scale-electric fields, related to the low latitude magnetospheric-ionospheric coupling and to the local atmospheric electrodynamics, using detectors on board stratospheric balloons; and d) measurements of atmospheric X-rays, related to the process of energetic particle precipitation at the South Atlantic Magnetic Anomaly, using detectors also on board stratospheric balloons. Similarly, the following research activities related to geomagnetism are being pursued: a) studies on the variability of the geomagnetic field and on the dynamics of the equatorial electrojet from local geomagnetic field measurements; b) studies on terrestrial electromagnetic induction through local measurements of the geo-electromagnetic field; and c) studies on the influence of geomagnetic activity on particle precipitation at the South Atlantic Magnetic Anomaly. (Author) [pt

  15. Geomagnetically Induced Currents Around the World During the 17 March 2015 Storm

    Science.gov (United States)

    Carter, B. A.; Yizengaw, E.; Pradipta, R.; Weygand, J. M.; Piersanti, M.; Pulkkinen, Antti Aleksi; Moldwin, M. B.; Norman, R.; Zhang, K.

    2016-01-01

    Geomagnetically induced currents (GICs) represent a significant space weather issue for power grid and pipeline infrastructure, particularly during severe geomagnetic storms. In this study, magnetometer data collected from around the world are analyzed to investigate the GICs caused by the 2015 St. Patricks Day storm. While significant GIC activity in the high-latitude regions due to storm time substorm activity is shown for this event, enhanced GIC activity was also measured at two equatorial stations in the American and Southeast Asian sectors. This equatorial GIC activity is closely examined, and it is shown that it is present both during the arrival of the interplanetary shock at the storm sudden commencement (SSC) in Southeast Asia and during the main phase of the storm approximately 10 h later in South America. The SSC caused magnetic field variations at the equator in Southeast Asia that were twice the magnitude of those observed only a few degrees to the north, strongly indicating that the equatorial electrojet (EEJ) played a significant role. The large equatorial magnetic field variations measured in South America are also examined, and the coincident solar wind data are used to investigate the causes of the sudden changes in the EEJ approximately 10 h into the storm. From this analysis it is concluded that sudden magnetopause current increases due to increases in the solarwind dynamic pressure, and the sudden changes in the resultant magnetospheric and ionospheric current systems, are the primary drivers of equatorial GICs.

  16. Letter to the Editor: Geomagnetic storm effects at low latitudes

    OpenAIRE

    R. G. Rastogi; R. G. Rastogi

    1999-01-01

    The geomagnetic horizontal (H) field from the chain of nine observatories in India are used to study the storm-time and disturbance daily variations. The peak decrease in storm-time variation in H showed significant enhancements at the equatorial electrojet stations over and above the normally expected decrease due to the ring current effects corrected for geomagnetic latitudes. The disturbance daily variation of H at equatorial stations showed a large decrease around midday...

  17. Geomagnetic storm effects on GPS based navigation

    Directory of Open Access Journals (Sweden)

    P. V. S. Rama Rao

    2009-05-01

    Full Text Available The energetic events on the sun, solar wind and subsequent effects on the Earth's geomagnetic field and upper atmosphere (ionosphere comprise space weather. Modern navigation systems that use radio-wave signals, reflecting from or propagating through the ionosphere as a means of determining range or distance, are vulnerable to a variety of effects that can degrade the performance of the navigational systems. In particular, the Global Positioning System (GPS that uses a constellation of earth orbiting satellites are affected due to the space weather phenomena.

    Studies made during two successive geomagnetic storms that occurred during the period from 8 to 12 November 2004, have clearly revealed the adverse affects on the GPS range delay as inferred from the Total Electron Content (TEC measurements made from a chain of seven dual frequency GPS receivers installed in the Indian sector. Significant increases in TEC at the Equatorial Ionization anomaly crest region are observed, resulting in increased range delay during the periods of the storm activity. Further, the storm time rapid changes occurring in TEC resulted in a number of phase slips in the GPS signal compared to those on quiet days. These phase slips often result in the loss of lock of the GPS receivers, similar to those that occur during strong(>10 dB L-band scintillation events, adversely affecting the GPS based navigation.

  18. Plasmaspheric noise radiation during geomagnetic storms

    International Nuclear Information System (INIS)

    Larkina, V.I.; Likhter, Ya.I.

    1981-01-01

    Variations of plasmospheric background radiations during geomagnetic storms of different intensity are investigated. Used are results of ELF and VLF radiation measurements as well as electron fluxes of energies Esub(e)>40 keV carried out by Intercosmos 3 and Intercosmos 5 satellites. Dependences of radiation amplitude variations at 1.6 and 25 kHz frequencies on L shell for various geomagnetic activity in the day-time as well as data on variations of quasicaptured electron fluxes at Esub(e)>40 keV, are given. It is shown that experimental data agree with the existing theories of plasmospheric noise excitation. It is concluded that the plasmospheric noise excitation area Lsub(max) is always in the region of gap between radiation belts and inner slope of external radiation belt during magnetic storms. During magnetic storms Lsub(max) area moves simultaneously with the area, where particle flux of the external radiation belt is the most intensive [ru

  19. Ice ages and geomagnetic reversals

    Science.gov (United States)

    Wu, Patrick

    1992-01-01

    There have been speculations on the relationship between climatic cooling and polarity reversals of the earth's magnetic field during the Pleistocene. Two of the common criticisms on this relationship have been the reality of these short duration geomagnetic events and the accuracy of their dates. Champion et al. (1988) have reviewed recent progress in this area. They identified a total of 10 short-duration polarity events in the last 1 Ma and 6 of these events have been found in volcanic rocks, which also have K-Ar dates. Supposing that the speculated relationship between climatic cooling and geomagnetic reversals actually exist, two mechanisms that assume climatic cooling causes short period magnetic reversals will be investigated. These two methods are core-mantle boundary topography and transfer of the rotational energy to the core.

  20. Hydrolytic enzyme activity enhanced by Barium supplementation

    Directory of Open Access Journals (Sweden)

    Camilo Muñoz

    2016-10-01

    Full Text Available Hydrolysis of polymers is a first and often limiting step during the degradation of plant residues. Plant biomass is generally a major component of waste residues and a major renewable resource to obtain a variety of secondary products including biofuels. Improving the performance of enzymatic hydrolysis of plant material with minimum costs and limiting the use of additional microbial biomass or hydrolytic enzymes directly influences competitiveness of these green biotechnological processes. In this study, we cloned and expressed a cellulase and two esterases recovered from environmental thermophilic soil bacterial communities and characterize their optimum activity conditions including the effect of several metal ions. Results showed that supplementing these hydrolytic reactions with Barium increases the activity of these extracellular hydrolytic enzymes. This observation represents a simple but major improvement to enhance the efficiency and competitiveness of this process within an increasingly important biotechnological sector.

  1. Geomagnetic Observations for Main Field Studies

    DEFF Research Database (Denmark)

    Matzka, Jürgen; Chulliat, A.; Mandea, M.

    2010-01-01

    Direct measurements of the geomagnetic field have been made for more than 400 years, beginning with individual determinations of the angle between geographic and magnetic North. This was followed by the start of continuous time series of full vector measurements at geomagnetic observatories...... and the beginning of geomagnetic repeat stations surveys in the 19th century. In the second half of the 20th century, true global coverage with geomagnetic field measurements was accomplished by magnetometer payloads on low-Earth-orbiting satellites. This article describes the procedures and instruments...... for magnetic field measurements on ground and in space and covers geomagnetic observatories, repeat stations, automatic observatories, satellites and historic observations. Special emphasis is laid on the global network of geomagnetic observatories....

  2. The Geomagnetic Field During a Reversal

    Science.gov (United States)

    Heirtzler, James R.

    2003-01-01

    By modifying the IGRF it is possible to learn what may happen to the geomagnetic field during a geomagnetic reversal. If the entire IGRF reverses then the declination and inclination only reverse when the field strength is zero. If only the dipole component of the IGRF reverses a large geomagnetic field remains when the dipole component is zero and he direction of the field at the end of the reversal is not exactly reversed from the directions at the beginning of the reversal.

  3. The effect of solar-geomagnetic activity during hospital admission on coronary events within 1 year in patients with acute coronary syndromes

    Science.gov (United States)

    Vencloviene, J.; Babarskiene, R.; Milvidaite, I.; Kubilius, R.; Stasionyte, J.

    2013-12-01

    Some evidence indicates the deterioration of the cardiovascular system during space storms. It is plausible that the space weather conditions during and after hospital admission may affect the risk of coronary events in patients with acute coronary syndromes (ACS). We analyzed the data of 1400 ACS patients who were admitted to the Hospital Lithuanian University of Health Sciences, and who survived for more than 4 days. We evaluated the associations between geomagnetic storms (GS), solar proton events (SPE), and solar flares (SF) that occurred 0-3 days before and after hospital admission and the risk of cardiovascular death (CAD), non-fatal ACS, and coronary artery bypass grafting (CABG) during a period of 1 year; the evaluation was based on the multivariate logistic model, controlling for clinical data. After adjustment for clinical variables, GS occurring in conjunction with SF 1 day before admission increased the risk of CAD by over 2.5 times. GS 2 days after SPE occurred 1 day after admission increased the risk of CAD and CABG by over 2.8 times. The risk of CABG increased by over 2 times in patients admitted during the day of GS and 1 day after SPE. The risk of ACS was by over 1.63 times higher for patients admitted 1 day before or after solar flares.

  4. Linkage between the Biosphere and Geomagnetic field: Knowns and Unknowns

    Science.gov (United States)

    Pan, Y.; Zhu, R.

    2017-12-01

    The geomagnetic field extends from Earth's interior into space, and protects our planets habitability by shielding the planet from solar winds and cosmic rays. Recently, single zircon paleomagnetic study provides evidence of the field to ages as old as 4.2 Ga. Many great questions remain, including whether the emergence of life on Earth was a consequence of the field's protection, how organisms utilize the field, and if field variations (polarity reversal, excursion and secular variation) impact the evolution of the biosphere. In the past decade, great efforts have been made to probe these very complex and great challenging questions through the inter-disciplinary subject of biogeomagnetism. Numerous birds, fish, sea turtles, bats and many other organisms utilize the geomagnetic field during orientation and long-distance navigation. We recently found that bats, the second most abundant order of mammals, can use the direction of magnetic field with a weak strength comparable to polarity transitions/excursions, which is indicative of advanced magnetoreception developed in bats co-evolving with the geomagnetic field since the Eocene. Magnetotactic bacteria swim along the geomagnetic field lines by synthesizing intracellular nano-sized and chain-arranged magnetic minerals (magnetosomes). Recent field surveys in China, Europe, America and Australia have shown that these microbes are ubiquitous in aqueous habitats. Both their biogeography distribution and magnetotactic swimming speed are field intensity dependent. On the other hand, it is increasingly accepted that the geomagnetic field influences life through several indirect pathways. For example, it has been discovered that solar wind erosion enhanced the atmospheric oxygen escape during periods of weak magnetic field and global mean ionospheric electron density profiles can be affected by geomagnetic field strength variation. In addition, depletion of the ozone layer during a weak magnetic field could result in

  5. Propagation of low frequency geomagnetic field fluctuations in Antarctica: comparison between two polar cap stations

    Directory of Open Access Journals (Sweden)

    L. Santarelli

    2007-11-01

    Full Text Available We conduct a statistical analysis of the coherence and phase difference of low frequency geomagnetic fluctuations between two Antarctic stations, Mario Zucchelli Station (geographic coordinates: 74.7° S, 164.1° E; corrected geomagnetic coordinates: 80.0° S, 307.7° E and Scott Base (geographic coordinates: 77.8° S 166.8° E; corrected geomagnetic coordinates: 80.0° S 326.5° E, both located in the polar cap. Due to the relative position of the stations, whose displacement is essentially along a geomagnetic parallel, the phase difference analysis allows to determine the direction of azimuthal propagation of geomagnetic fluctuations. The results show that coherent fluctuations are essentially detectable around local geomagnetic midnight and, in a minor extent, around noon; moreover, the phase difference reverses in the night time hours, indicating a propagation direction away from midnight, and also around local geomagnetic noon, indicating a propagation direction away from the subsolar point. The nigh time phase reversal is more clear for southward interplanetary magnetic field conditions, suggesting a relation with substorm activity.

    The introduction, in this analysis, of the Interplanetary Magnetic Field conditions, gave interesting results, indicating a relation with substorm activity during nighttime hours.

    We also conducted a study of three individual pulsation events in order to find a correspondence with the statistical behaviour. In particular, a peculiar event, characterized by quiet magnetospheric and northward interplanetary magnetic field conditions, shows a clear example of waves propagating away from the local geomagnetic noon; two more events, occurring during southward interplanetary magnetic field conditions, in one case even during a moderate storm, show waves propagating away from the local geomagnetic midnight.

  6. Propagation of low frequency geomagnetic field fluctuations in Antarctica: comparison between two polar cap stations

    Directory of Open Access Journals (Sweden)

    L. Santarelli

    2007-11-01

    Full Text Available We conduct a statistical analysis of the coherence and phase difference of low frequency geomagnetic fluctuations between two Antarctic stations, Mario Zucchelli Station (geographic coordinates: 74.7° S, 164.1° E; corrected geomagnetic coordinates: 80.0° S, 307.7° E and Scott Base (geographic coordinates: 77.8° S 166.8° E; corrected geomagnetic coordinates: 80.0° S 326.5° E, both located in the polar cap. Due to the relative position of the stations, whose displacement is essentially along a geomagnetic parallel, the phase difference analysis allows to determine the direction of azimuthal propagation of geomagnetic fluctuations. The results show that coherent fluctuations are essentially detectable around local geomagnetic midnight and, in a minor extent, around noon; moreover, the phase difference reverses in the night time hours, indicating a propagation direction away from midnight, and also around local geomagnetic noon, indicating a propagation direction away from the subsolar point. The nigh time phase reversal is more clear for southward interplanetary magnetic field conditions, suggesting a relation with substorm activity. The introduction, in this analysis, of the Interplanetary Magnetic Field conditions, gave interesting results, indicating a relation with substorm activity during nighttime hours. We also conducted a study of three individual pulsation events in order to find a correspondence with the statistical behaviour. In particular, a peculiar event, characterized by quiet magnetospheric and northward interplanetary magnetic field conditions, shows a clear example of waves propagating away from the local geomagnetic noon; two more events, occurring during southward interplanetary magnetic field conditions, in one case even during a moderate storm, show waves propagating away from the local geomagnetic midnight.

  7. Extreme Geomagnetic Storms – 1868–2010

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Lefèvre, L.; Dumbović, M.

    2016-01-01

    presents our investigation of the corresponding solar eventsand their characteristics. The storms were selected based on their intensity in the aa index,which constitutes the longest existing continuous series of geomagnetic activity. They areanalyzed statistically in the context of more well...... occurring in May 1921 and the Quebec storm from March 1989. We identifykey characteristics of the storms by combining several different available data sources, listsof storm sudden commencements (SSCs) signifying occurrence of interplanetary shocks,solar wind in-situ measurements, neutron monitor data...... %), Forbushdecreases (100 %), and energetic solar proton events (70 %). A quantitative comparison ofthese associations relative to less intense storms is also presented. Most notably, we findthat most often the extreme storms are characterized by a complexity that is associated with multiple, often interacting, solar...

  8. Volcano Popocatepetl, Mexico: ULF geomagnetic anomalies observed at Tlamacas station during March–July, 2005

    Directory of Open Access Journals (Sweden)

    A. Kotsarenko

    2007-01-01

    Full Text Available In this paper the first results of ULF (Ultra Low Frequency geomagnetic anomalies observed at Tlamacas station (Long. 261.37, Lat. 19.07 located at 4 km near the volcano Popocatepetl (active volcano, Long. 261.37, Lat. 19.02 for the period March–July, 2005 and their analysis are presented. The geomagnetic data were collected with a 3-axial fluxgate magnetometer designed at UCLA (University of California, Los Angeles, 1 Hz sampling rate frequency, GPS. Our analysis reveals some anomalies which are suspected to be generated by local volcanic origin: the EM background in the vicinity of the volcano is significantly noisier than in other reference stations; the sporadic strong noise-like geomagnetic activity observed in the H-component; locally generated geomagnetic pulsations (without preferred polarization are detected only at Tlamacas station.

  9. High resolution geomagnetic field observations at Terra Nova bay, Antarctica

    Directory of Open Access Journals (Sweden)

    P. Palangio

    1996-06-01

    Full Text Available he preliminary results obtained from the analysis in the micropulsation frequency range of high time resolution magnetic field data recorded at the Antarctic Italian geomagnetic observatory at Terra Nova Bay for 11 consecutive days in February 1994 are reported. The spectral index over the whole Pcl-Pc5 frequency range is of the order of 3.5 and its value significantly increases beyond about 50 mHz. Spectral peaks in the Pc3 frequency range are common, especially during the daytime hours, and are probably due to the direct penetration of upstream waves in the cusp region. From the local time distribution of the micro pulsation power, a signifi - cant activity enhancement around the local magnetic noon emerges, in agreement with previous observations. The analysis of the signal polarisation characteristics in the horizontal plane shows a predominant CW polarisation in the Pcl-Pc3 frequency ranges with the major axis of the polarisation ellipse in the first quadrant.

  10. Phanerochaete mutants with enhanced ligninolytic activity

    International Nuclear Information System (INIS)

    Kakar, S.N.; Perez, A.; Gonzales, J.

    1994-01-01

    In addition to lignin, the white rot fungus Phanerochaete chrysosporium has the ability to degrade a wide spectrum of recalcitrant organo pollutants in soils and aqueous media. Most of the organic compounds are degraded under ligninolytic conditions with the involvement of the extracellular enzymes, lignin peroxidases, and manganese-dependent peroxidases, which are produced as secondary metabolites triggered by conditions of nutrient starvation (e.g., nitrogen limitation). The fungus and its enzymes can thus provide alternative technologies for bioremediation, bio pulping, bio bleaching, and other industrial applications. The efficiency and effectiveness of the fungus can be enhanced by increasing production and secretion of the important enzymes in large quantities and as primary metabolites under enriched conditions. One way this can be achieved is through isolation of mutants that are deregulated, or are hyper producers or super secretors of key enzymes under enriched conditions. Through UV-light and γ-ray mutagenesis, we have isolated a variety of mutants, some of which produce key enzymes of the ligninolytic system under high-nitrogen growth conditions. One of the mutants, 76UV, produced 272 U of lignin peroxidases enzyme activity/L after 9 d under high nitrogen (although the parent strain does not produce this enzyme under these conditions). The mutant and the parent strains produced up to 54 and 62 U/L, respectively, of the enzyme activity under low nitrogen growth conditions during this period. In some experiments, the mutant showed 281 U/L of enzyme activity under high nitrogen after 17 d

  11. Letter to the Editor: Geomagnetic storm effects at low latitudes

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    Full Text Available The geomagnetic horizontal (H field from the chain of nine observatories in India are used to study the storm-time and disturbance daily variations. The peak decrease in storm-time variation in H showed significant enhancements at the equatorial electrojet stations over and above the normally expected decrease due to the ring current effects corrected for geomagnetic latitudes. The disturbance daily variation of H at equatorial stations showed a large decrease around midday hours over and above the usual dawn-maximum and dusk-minimum seen at any mid-latitude stations around the world. These slow and persistent additional decreases of H of disturbance daily variation at equatorial latitudes could be the effect of a westward electric field due to the Disturbance Ionospheric dynamo coupled with abnormally large electrical conductivities in the E region over the equator.Key words. Ionosphere (electric fields and currents · Magnetospheric physics (electric fields; storms and substorms

  12. Letter to the Editor: Geomagnetic storm effects at low latitudes

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    1999-03-01

    Full Text Available The geomagnetic horizontal (H field from the chain of nine observatories in India are used to study the storm-time and disturbance daily variations. The peak decrease in storm-time variation in H showed significant enhancements at the equatorial electrojet stations over and above the normally expected decrease due to the ring current effects corrected for geomagnetic latitudes. The disturbance daily variation of H at equatorial stations showed a large decrease around midday hours over and above the usual dawn-maximum and dusk-minimum seen at any mid-latitude stations around the world. These slow and persistent additional decreases of H of disturbance daily variation at equatorial latitudes could be the effect of a westward electric field due to the Disturbance Ionospheric dynamo coupled with abnormally large electrical conductivities in the E region over the equator.Key words. Ionosphere (electric fields and currents · Magnetospheric physics (electric fields; storms and substorms

  13. Long-term biases in geomagnetic K and aa indices

    Science.gov (United States)

    Love, J.J.

    2011-01-01

    Analysis is made of the geomagnetic-activity aa index and its source K-index data from groups of ground-based observatories in Britain, and Australia, 1868.0-2009.0, solar cycles 11-23. The K data show persistent biases, especially for high (low) K-activity levels at British (Australian) observatories. From examination of multiple subsets of the K data we infer that the biases are not predominantly the result of changes in observatory location, localized induced magnetotelluric currents, changes in magnetometer technology, or the modernization of K-value estimation methods. Instead, the biases appear to be artifacts of the latitude-dependent scaling used to assign K values to particular local levels of geomagnetic activity. The biases are not effectively removed by weighting factors used to estimate aa. We show that long-term averages of the aa index, such as annual averages, are dominated by medium-level geomagnetic activity levels having K values of 3 and 4. ?? 2011 Author(s).

  14. Long-term biases in geomagnetic K and aa indices

    Directory of Open Access Journals (Sweden)

    J. J. Love

    2011-08-01

    Full Text Available Analysis is made of the geomagnetic-activity aa index and its source K-index data from groups of ground-based observatories in Britain, and Australia, 1868.0–2009.0, solar cycles 11–23. The K data show persistent biases, especially for high (low K-activity levels at British (Australian observatories. From examination of multiple subsets of the K data we infer that the biases are not predominantly the result of changes in observatory location, localized induced magnetotelluric currents, changes in magnetometer technology, or the modernization of K-value estimation methods. Instead, the biases appear to be artifacts of the latitude-dependent scaling used to assign K values to particular local levels of geomagnetic activity. The biases are not effectively removed by weighting factors used to estimate aa. We show that long-term averages of the aa index, such as annual averages, are dominated by medium-level geomagnetic activity levels having K values of 3 and 4.

  15. Solar cycle effect on geomagnetic storms caused by interplanetary magnetic clouds

    Directory of Open Access Journals (Sweden)

    C.-C. Wu

    2006-12-01

    Full Text Available We investigated geomagnetic activity which was induced by interplanetary magnetic clouds during the past four solar cycles, 1965–1998. We have found that the intensity of such geomagnetic storms is more severe in solar maximum than in solar minimum. In addition, we affirm that the average solar wind speed of magnetic clouds is faster in solar maximum than in solar minimum. In this study, we find that solar activity level plays a major role on the intensity of geomagnetic storms. In particular, some new statistical results are found and listed as follows. (1 The intensity of a geomagnetic storm in a solar active period is stronger than in a solar quiet period. (2 The magnitude of negative Bzmin is larger in a solar active period than in a quiet period. (3 Solar wind speed in an active period is faster than in a quiet period. (4 VBsmax in an active period is much larger than in a quiet period. (5 Solar wind parameters, Bzmin, Vmax and VBsmax are correlated well with geomagnetic storm intensity, Dstmin during a solar active period. (6 Solar wind parameters, Bzmin, and VBsmax are not correlated well (very poorly for Vmax with geomagnetic storm intensity during a solar quiet period. (7 The speed of the solar wind plays a key role in the correlation of solar wind parameters vs. the intensity of a geomagnetic storm. (8 More severe storms with Dstmin≤−100 nT caused by MCs occurred in the solar active period than in the solar quiet period.

  16. Kinematic reversal schemes for the geomagnetic dipole.

    Science.gov (United States)

    Levy, E. H.

    1972-01-01

    Fluctuations in the distribution of cyclonic convective cells, in the earth's core, can reverse the sign of the geomagnetic field. Two kinematic reversal schemes are discussed. In the first scheme, a field maintained by cyclones concentrated at low latitude is reversed by a burst of cyclones at high latitude. Conversely, in the second scheme, a field maintained predominantly by cyclones in high latitudes is reversed by a fluctuation consisting of a burst of cyclonic convection at low latitude. The precise fluid motions which produce the geomagnetic field are not known. However, it appears that, whatever the details are, a fluctuation in the distribution of cyclonic cells over latitude can cause a geomagnetic reversal.

  17. Real-time geomagnetic monitoring for space weather-related applications: Opportunities and challenges

    Science.gov (United States)

    Love, Jeffrey J.; Finn, Carol A.

    2017-07-01

    An examination is made of opportunities and challenges for enhancing global, real-time geomagnetic monitoring that would be beneficial for a variety of operational projects. This enhancement in geomagnetic monitoring can be attained by expanding the geographic distribution of magnetometer stations, improving the quality of magnetometer data, increasing acquisition sampling rates, increasing the promptness of data transmission, and facilitating access to and use of the data. Progress will benefit from new partnerships to leverage existing capacities and harness multisector, cross-disciplinary, and international interests.

  18. The geomagnetic field gradient tensor

    DEFF Research Database (Denmark)

    Kotsiaros, Stavros; Olsen, Nils

    2012-01-01

    We develop the general mathematical basis for space magnetic gradiometry in spherical coordinates. The magnetic gradient tensor is a second rank tensor consisting of 3 × 3 = 9 spatial derivatives. Since the geomagnetic field vector B is always solenoidal (∇ · B = 0) there are only eight independent...... tensor elements. Furthermore, in current free regions the magnetic gradient tensor becomes symmetric, further reducing the number of independent elements to five. In that case B is a Laplacian potential field and the gradient tensor can be expressed in series of spherical harmonics. We present properties...... of the magnetic gradient tensor and provide explicit expressions of its elements in terms of spherical harmonics. Finally we discuss the benefit of using gradient measurements for exploring the Earth’s magnetic field from space, in particular the advantage of the various tensor elements for a better determination...

  19. Space Weather Monitoring for ISS Geomagnetic Storm Studies

    Science.gov (United States)

    Minow, Joseph I.; Parker, Linda Neergaard

    2013-01-01

    The International Space Station (ISS) space environments community utilizes near real time space weather data to support a variety of ISS engineering and science activities. The team has operated the Floating Potential Measurement Unit (FPMU) suite of plasma instruments (two Langmuir probes, a floating potential probe, and a plasma impedance probe) on ISS since 2006 to obtain in-situ measurements of plasma density and temperature along the ISS orbit and variations in ISS frame potential due to electrostatic current collection from the plasma environment (spacecraft charging) and inductive (vxB) effects from the vehicle motion across the Earth s magnetic field. An ongoing effort is to use FPMU for measuring the ionospheric response to geomagnetic storms at ISS altitudes and investigate auroral charging of the vehicle as it passes through regions of precipitating auroral electrons. This work is challenged by restrictions on FPMU operations that limit observation time to less than about a third of a year. As a result, FPMU campaigns ranging in length from a few days to a few weeks are typically scheduled weeks in advance for ISS engineering and payload science activities. In order to capture geomagnetic storm data under these terms, we monitor near real time space weather data from NASA, NOAA, and ESA sources to determine solar wind disturbance arrival times at Earth likely to be geoeffective (including coronal mass ejections and high speed streams associated with coronal holes) and activate the FPMU ahead of the storm onset. Using this technique we have successfully captured FPMU data during a number of geomagnetic storm periods including periods with ISS auroral charging. This presentation will describe the strategies and challenges in capturing FPMU data during geomagnetic storms, the near real time space weather resources utilized for monitoring the space weather environment, and provide examples of auroral charging data obtained during storm operations.

  20. The International Geomagnetic Reference Field: the twelfth generation

    Science.gov (United States)

    Thebault, Erwan; Finlay, Christopher; The IGRF Working Group

    2015-04-01

    The IGRF is an internationally-agreed reference model of the Earth's magnetic field produced under the auspices of the International Association of Geomagnetism and Aeronomy. The IGRF-12 is the latest update of this well-known model which is used each year by many thousands of users for both industrial and scientific purposes. In October 2014, ten institutions worldwide have made contributions to the IGRF. These models were evaluated and the twelfth generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014. In this presentation, we will report on the IGRF activities, briefly describe the candidate models, summarize the evaluation of models performed by different independent teams, show how the IGRF-12 models were calculated and finally discuss some of the main magnetic features of this new model.

  1. Geomagnetic storms in the Antarctic F-region

    International Nuclear Information System (INIS)

    Wrenn, G.L.; Rodger, A.S.; Rishbeth, H.

    1987-01-01

    New analysis procedures are used to show that the main phase mid-latitude storm effects conform to consistent patterns in local time when suitable selection rules are applied, with averaging over several years. Changes in the maximum plasma frequency, foF2, with respect to estimated quiet-time values, are analysed in terms of asub(p)(t), a new geomagnetic index derived to take account of integrated disturbance. Reduction of foF2 is greatest during the early morning hours, in summer, at higher geomagnetic latitudes, near solar minimum and through the more active periods. The various dependencies are quantitatively determined for the first time by creating an average 'steady state' disturbance, rather than following specific storm events. This approach permits tests of competing theories using available modelling programs. (author)

  2. Geomagnetic Observatory Data for Real-Time Applications

    Science.gov (United States)

    Love, J. J.; Finn, C. A.; Rigler, E. J.; Kelbert, A.; Bedrosian, P.

    2015-12-01

    The global network of magnetic observatories represents a unique collective asset for the scientific community. Historically, magnetic observatories have supported global magnetic-field mapping projects and fundamental research of the Earth's interior and surrounding space environment. More recently, real-time data streams from magnetic observatories have become an important contributor to multi-sensor, operational monitoring of evolving space weather conditions, especially during magnetic storms. In this context, the U.S. Geological Survey (1) provides real-time observatory data to allied space weather monitoring projects, including those of NOAA, the U.S. Air Force, NASA, several international agencies, and private industry, (2) collaborates with Schlumberger to provide real-time geomagnetic data needed for directional drilling for oil and gas in Alaska, (3) develops products for real-time evaluation of hazards for the electric-power grid industry that are associated with the storm-time induction of geoelectric fields in the Earth's conducting lithosphere. In order to implement strategic priorities established by the USGS Natural Hazards Mission Area and the National Science and Technology Council, and with a focus on developing new real-time products, the USGS is (1) leveraging data management protocols already developed by the USGS Earthquake Program, (2) developing algorithms for mapping geomagnetic activity, a collaboration with NASA and NOAA, (3) supporting magnetotelluric surveys and developing Earth conductivity models, a collaboration with Oregon State University and the NSF's EarthScope Program, (4) studying the use of geomagnetic activity maps and Earth conductivity models for real-time estimation of geoelectric fields, (5) initiating geoelectric monitoring at several observatories, (6) validating real-time estimation algorithms against historical geomagnetic and geoelectric data. The success of these long-term projects is subject to funding constraints

  3. Characterization and demonstration results of a SQUID magnetometer system developed for geomagnetic field measurements

    Science.gov (United States)

    Kawai, J.; Miyamoto, M.; Kawabata, M.; Nosé, M.; Haruta, Y.; Uehara, G.

    2017-08-01

    We characterized a low temperature superconducting quantum interference device (SQUID) magnetometer system developed for high-sensitivity geomagnetic field measurement, and demonstrated the detection of weak geomagnetic signals. The SQUID magnetometer system is comprised of three-axis SQUID magnetometers housed in a glass fiber reinforced plastic cryostat, readout electronics with flux locked loop (FLL), a 24-bit data logger with a global positioning system and batteries. The system noise was approximately 0.2 pT √Hz- 1/2 in the 1-50 Hz frequency range. This performance was determined by including the thermal noise and the shielding effect of the copper shield, which covered the SQUID magnetometers to eliminate high-frequency interference. The temperature drift of the system was ˜0.8 pT °C- 1 in an FLL operation. The system operated for a month using 33 l liquid helium. Using this system, we performed the measurements of geomagnetic field in the open-air, far away from the city. The system could detect weak geomagnetic signals such as the Schumann resonance with sixth harmonics, and the ionospheric Alfvén resonance appearing at night, for the north-south and east-west components of the geomagnetic field. We confirm that the system was capable of high-sensitivity measurement of the weak geomagnetic activities.

  4. Geomagnetism solid Earth and upper atmosphere perspectives

    CERN Document Server

    Basavaiah, Nathani

    2011-01-01

    This volume elaborates several important aspects of solid Earth geomagnetism. It covers all the basics of the subject, including biomagnetism and instrumentation, and offers a number of practical applications with carefully selected examples and illustrations.

  5. The Development of Models for Assessment of the Geomagnetically Induced Currents Impact on Electric Power Grids during Geomagnetic Storms

    Directory of Open Access Journals (Sweden)

    VAKHNINA, V. V.

    2015-02-01

    Full Text Available A model and an algorithm for the calculation of the functioning of an electric power grid of arbitrary configuration and complexity during geomagnetic storms were developed. The calculations were performed in the MATLAB mathematical package and the Simulink environment. The binding of objects to geographical coordinates is realized in the model, which enables to determine the matrix of potentials of geoelectric fields in nodal points. In order to define the instantaneous magnetizing currents, the power transformers are designed on the basis of the T-shaped equivalent circuit with a nonlinear mutual inductance of magnetization branch. Calculation of RMS values of active, reactive and total power values in all the elements is done with regard to the impact of harmonic components of the current and voltage. The results of modeling of the impact of geomagnetic storms of various intensity with the west-east direction of the geoelectric field vector for Samara region electric power grid are given.

  6. Magnetotactic bacteria at the geomagnetic equator

    International Nuclear Information System (INIS)

    Frankel, R.B.; Blakemore, R.P.; Araujo, F.F.T. de; Esquivel, D.M.S.; Danon, J.

    1981-01-01

    Magnetotatic bacteria are observed in freshwater and marine sediments of Fortaleza, Brazil, situated close to the geomagnetic equator. Both South-seeking and North-seeking bacteria are present in roughly equal numbers in the same samples. This observation is consistent with the hypothesis that the vertical component of the geomagnetic field selects the predominant polarity type among magnetotactic bacteria in natural environments. (Author) [pt

  7. Toward a possible next geomagnetic transition?

    OpenAIRE

    A. De Santis; E. Qamili; L. Wu

    2013-01-01

    The geomagnetic field is subject to possible reversals or excursions of polarity during its temporal evolution. Considering that: (a) the typical average time between one reversal and the next (the so-called chron) is around 300 000 yr, (b) the last reversal occurred around 780 000 yr ago, (c) more excursions (rapid changes of polarity) can occur within the same chron and (d) the geomagnetic field dipole is currently decreasing, a possible imminent geomagne...

  8. How the geomagnetic field vector reverses polarity

    Science.gov (United States)

    Prevot, M.; Mankinen, E.A.; Gromme, C.S.; Coe, R.S.

    1985-01-01

    A highly detailed record of both the direction and intensity of the Earth's magnetic field as it reverses has been obtained from a Miocene volcanic sequence. The transitional field is low in intensity and is typically non-axisymmetric. Geomagnetic impulses corresponding to astonishingly high rates of change of the field sometimes occur, suggesting that liquid velocity within the Earth's core increases during geomagnetic reversals. ?? 1985 Nature Publishing Group.

  9. A Quaternary Geomagnetic Instability Time Scale

    Science.gov (United States)

    Singer, B. S.

    2013-12-01

    Reversals and excursions of Earth's geomagnetic field create marker horizons that are readily detected in sedimentary and volcanic rocks worldwide. An accurate and precise chronology of these geomagnetic field instabilities is fundamental to understanding several aspects of Quaternary climate, dynamo processes, and surface processes. For example, stratigraphic correlation between marine sediment and polar ice records of climate change across the cryospheres benefits from a highly resolved record of reversals and excursions. The temporal patterns of dynamo behavior may reflect physical interactions between the molten outer core and the solid inner core or lowermost mantle. These interactions may control reversal frequency and shape the weak magnetic fields that arise during successive dynamo instabilities. Moreover, weakening of the axial dipole during reversals and excursions enhances the production of cosmogenic isotopes that are used in sediment and ice core stratigraphy and surface exposure dating. The Geomagnetic Instability Time Scale (GITS) is based on the direct dating of transitional polarity states recorded by lava flows using the 40Ar/39Ar method, in parallel with astrochronologic age models of marine sediments in which O isotope and magnetic records have been obtained. A review of data from Quaternary lava flows and sediments yields a GITS comprising 10 polarity reversals and 27 excursions during the past 2.6 million years. Nine of the ten reversals bounding chrons and subchrons are associated with 40Ar/39Ar ages of transitionally-magnetized lava flows. The tenth, the Guass-Matuyama chron boundary, is tightly bracketed by 40Ar/39Ar dated ash deposits. Of the 27 well-documented excursions, 14 occurred during the Matuyama chron and 13 during the Brunhes chron; 19 have been dated directly using the 40Ar/39Ar method on transitionally-magnetized volcanic rocks and form the backbone of the GITS. Excursions are clearly not the rare phenomena once thought

  10. Memory enhancing activity of Spondias mombin Anarcadiaceae ...

    African Journals Online (AJOL)

    Background: In traditional medical practices, several plants have been used to treat cognitive disorders associated with aging as well as neurodegenerative diseases such as Alzheimer's. Spondias mombin and Pycnanthus angolensis were found among recipes used ethnomedicine in Nigeria as memory enhancer.

  11. A new regard about Surlari National Geomagnetic Observatory

    Science.gov (United States)

    Asimopolos, Laurentiu; Asimopolos, Natalia-Silvia; Pestina, Agata-Monica

    2010-05-01

    Geomagnetic field study in Romanian stations has started with irregular measurements in late XIXth century. In 1943, the foundation of Surlari National Geomagnetic Observatory (SNGO) marks the beginning of a new era in the systematic study of geomagnetic field by a continuous registration of its variations and by carrying out standard absolute measurements in a fundamental station. The location of the observatory meets the highest exigencies, being situated in physical-geological conditions of a uniform local field, at a reasonably long distance from human activities. Its laboratories observe strict conditions of non-magnetism, ensuring the possibility of absolute standard measurements (national magnetic standards) for all the units in the country, civil or military, which are endowed with equipment based on geomagnetic metrology. These basic conditions have allowed the observatory to become by developing its initial preoccupations a centre of complex geomagnetic research, constantly involved in national and international issues, promoting new themes in our country and bringing significant contributions. During the last two decades, infrastructure and equipment used in monitoring geomagnetic field at European and planetary level have experienced a remarkable development. New registering techniques have allowed a complete to automate of data acquisition, and sampling step and their precision increased by two classes of size. Systems of transmitting these data in real time to world collecting centres have resulted in the possibility of approaching globalize studies, suitable for following some phenomena at planetary scale. At the same time, a significant development in the procedures of processing primary data has been registered, based on standardized programmes. The new stage of this fundamental research, largely applicable in various fields, is also marked by the simultaneous observation of space-time distribution of terrestrial electromagnetic field by means of

  12. Evaluation of geomagnetic field models using magnetometer measurements for satellite attitude determination system at low earth orbits: Case studies

    Science.gov (United States)

    Cilden-Guler, Demet; Kaymaz, Zerefsan; Hajiyev, Chingiz

    2018-01-01

    In this study, different geomagnetic field models are compared in order to study the errors resulting from the representation of magnetic fields that affect the satellite attitude system. For this purpose, we used magnetometer data from two Low Earth Orbit (LEO) spacecraft and the geomagnetic models IGRF-12 (Thébault et al., 2015) and T89 (Tsyganenko, 1989) models to study the differences between the magnetic field components, strength and the angle between the predicted and observed vector magnetic fields. The comparisons were made during geomagnetically active and quiet days to see the effects of the geomagnetic storms and sub-storms on the predicted and observed magnetic fields and angles. The angles, in turn, are used to estimate the spacecraft attitude and hence, the differences between model and observations as well as between two models become important to determine and reduce the errors associated with the models under different space environment conditions. We show that the models differ from the observations even during the geomagnetically quiet times but the associated errors during the geomagnetically active times increase. We find that the T89 model gives closer predictions to the observations, especially during active times and the errors are smaller compared to the IGRF-12 model. The magnitude of the error in the angle under both environmental conditions was found to be less than 1°. For the first time, the geomagnetic models were used to address the effects of the near Earth space environment on the satellite attitude.

  13. The Holocene Geomagnetic Field: Spikes, Low Field Anomalies, and Asymmetries

    Science.gov (United States)

    Constable, C.

    2017-12-01

    Our understanding of the Holocene magnetic field is constrained by individual paleomagnetic records of variable quality and resolution, composite regional secular variation curves, and low resolution global time-varying geomagnetic field models. Although spatial and temporal data coverages have greatly improved in recent years, typical views of millennial-scale secular variation and the underlying physical processes continue to be heavily influenced by more detailed field structure and short term variability inferred from the historical record and modern observations. Recent models of gyre driven decay of the geomagnetic dipole on centennial time scales, and studies of the evolution of the South Atlantic Anomaly provide one prominent example. Since 1840 dipole decay has largely been driven by meridional flux advection, with generally smaller fairly steady contributions from magnetic diffusion. The decay is dominantly associated with geomagnetic activity in the Southern Hemisphere. In contrast to the present decay, dipole strength generally grew between 1500 and 1000 BC, sustaining high but fluctuating values around 90-100 ZAm2 until after 1500 AD. Thus high dipole moments appear to have been present shortly after 1000 AD at the time of the Levantine spikes, which represent extreme variations in regional geomagnetic field strength. It has been speculated that the growth in dipole moment originated from a strong flux patch near the equatorial region at the core-mantle boundary that migrated north and west to augment the dipole strength, suggesting the presence of a large-scale anticyclonic gyre in the northern hemisphere, not totally unlike the southern hemisphere flow that dominates present day dipole decay. The later brief episodes of high field strength in the Levant may have contributed to prolonged values of high dipole strength until the onset of dipole decay in the late second millennium AD. This could support the concept of a large-scale stable flow

  14. The Complexity of Solar and Geomagnetic Indices

    Science.gov (United States)

    Pesnell, W. Dean

    2017-08-01

    How far in advance can the sunspot number be predicted with any degree of confidence? Solar cycle predictions are needed to plan long-term space missions. Fleets of satellites circle the Earth collecting science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Statistical and timeseries analyses of the sunspot number are often used to predict solar activity. These methods have not been completely successful as the solar dynamo changes over time and one cycle's sunspots are not a faithful predictor of the next cycle's activity. In some ways, using these techniques is similar to asking whether the stock market can be predicted. It has been shown that the Dow Jones Industrial Average (DJIA) can be more accurately predicted during periods when it obeys certain statistical properties than at other times. The Hurst exponent is one such way to partition the data. Another measure of the complexity of a timeseries is the fractal dimension. We can use these measures of complexity to compare the sunspot number with other solar and geomagnetic indices. Our concentration is on how trends are removed by the various techniques, either internally or externally. Comparisons of the statistical properties of the various solar indices may guide us in understanding how the dynamo manifests in the various indices and the Sun.

  15. Enhanced activation of the left hemisphere promotes normative decision making.

    Science.gov (United States)

    Corser, Ryan; Jasper, John D

    2014-01-01

    Previous studies have reported that enhanced activation of the left cerebral hemisphere reduces risky-choice, attribute, and goal-framing effects relative to enhanced activation of the right cerebral hemisphere. The present study sought to extend these findings and show that enhanced activation of the left hemisphere also reduces violations of other normative principles, besides the invariance principle. Participants completed ratio bias (Experiment 1, N = 296) and base rate neglect problems (Experiment 2, N = 145) under normal (control) viewing or with the right or left hemisphere primarily activated by imposing a unidirectional gaze. In Experiment 1 we found that enhanced left hemispheric activation reduced the ratio bias relative to normal viewing and a group experiencing enhanced right hemispheric activation. In Experiment 2 enhanced left hemispheric activation resulted in using base rates more than normal viewing, but not significantly more than enhanced right hemispheric activation. Results suggest that hemispheric asymmetries can affect higher-order cognitive processes, such as decision-making biases. Possible theoretical accounts are discussed as well as implications for dual-process theories.

  16. Solar causes of the excitation of earth electric currents and of geomagnetic field disturbances

    International Nuclear Information System (INIS)

    Krivsky, L.

    1977-01-01

    A survey is given of the effects of solar activity on geomagnetic and geoelectric disturbances. Indexes are given showing changes in the magnetic field, the occurrence of calm geomagnetic days related to solar activity, proton solar flares and electrical currents in the high layers of the atmosphere in the polar region, powerfull solar activity and electric currents in the polar region, the time rise of shock waves in the development of proton flares and the boundaries of sector structures of the interplanetary magnetic field and its effect on the Earth. It is stated that the geoelectric and geomagnetic fields are affected by the discrete phenomena of solar activity and by the transition of the quasimagnetic sectors of interplanetary fields. (J.P.)

  17. Enhancement of the Electrocatalytic Activity of Gold Nanoparticles via Anodic Treatment and the Decrease of the Enhanced Activity with Aging

    International Nuclear Information System (INIS)

    Jo, Kyung Min; Kang, Hyun Ju; Yang, Hae Sik

    2011-01-01

    We have recently shown that the electrocatalytic activity of Au nanoparticles (AuNPs) can be enhanced via NaBH 4 treatment and cathodic treatment and that the enhanced activity slowly decreases with aging. We have also demonstrated that the electrocatalytic activity of the AuNPs freshly prepared by electrochemical or chemical reduction slowly decreases with aging in both air and solution. Likewise, the electrocatalytic activity of anodically treated Au electrodes or AuNPs might change with aging. Herein, we report that the electrocatalytic activity of long-aged AuNPs can be enhanced via anodic treatment and that the enhanced electrocatalytic activity decreases with aging in air. The change in the electrocatalytic activity of AuNPs was evaluated by comparing cyclic voltammograms for the electrooxi-dation of hydrogen peroxide (H 2 O 2 ) and formic acid

  18. Modeling cancer registration processes with an enhanced activity diagram.

    Science.gov (United States)

    Lyalin, D; Williams, W

    2005-01-01

    Adequate instruments are needed to reflect the complexity of routine cancer registry operations properly in a business model. The activity diagram is a key instrument of the Unified Modeling Language (UML) for the modeling of business processes. The authors aim to improve descriptions of processes in cancer registration, as well as in other public health domains, through the enhancements of an activity diagram notation within the standard semantics of UML. The authors introduced the practical approach to enhance a conventional UML activity diagram, complementing it with the following business process concepts: timeline, duration for individual activities, responsibilities for individual activities within swimlanes, and descriptive text. The authors used an enhanced activity diagram for modeling surveillance processes in the cancer registration domain. Specific example illustrates the use of an enhanced activity diagram to visualize a process of linking cancer registry records with external mortality files. Enhanced activity diagram allows for the addition of more business concepts to a single diagram and can improve descriptions of processes in cancer registration, as well as in other domains. Additional features of an enhanced activity diagram allow to advance the visualization of cancer registration processes. That, in turn, promotes the clarification of issues related to the process timeline, responsibilities for particular operations, and collaborations among process participants. Our first experiences in a cancer registry best practices development workshop setting support the usefulness of such an approach.

  19. Enhancing Activity for the Oxygen Evolution Reaction

    DEFF Research Database (Denmark)

    Frydendal, Rasmus; Busch, Michael; Halck, Niels Bendtsen

    2014-01-01

    Electrochemical production of hydrogen, facilitated in electrolyzers, holds great promise for energy storage and solar fuel production. A bottleneck in the process is the catalysis of the oxygen evolution reaction, involving the transfer of four electrons. The challenge is that the binding energies...... of all reaction intermediates cannot be optimized individually. However, experimental investigations have shown that drastic improvements can be realized for manganese and cobalt-based oxides if gold is added to the surface or used as substrate. We propose an explanation for these enhancements based...... that the oxygen evolution reaction overpotential decreases by 100–300 mV for manganese oxides and 100 mV for cobalt oxides....

  20. Discovery of stimulation-responsive immune enhancers with CRISPR activation

    Science.gov (United States)

    Simeonov, Dimitre R.; Gowen, Benjamin G.; Boontanrart, Mandy; Roth, Theodore L.; Gagnon, John D.; Mumbach, Maxwell R.; Satpathy, Ansuman T.; Lee, Youjin; Bray, Nicolas L.; Chan, Alice Y.; Lituiev, Dmytro S.; Nguyen, Michelle L.; Gate, Rachel E.; Subramaniam, Meena; Li, Zhongmei; Woo, Jonathan M.; Mitros, Therese; Ray, Graham J.; Curie, Gemma L.; Naddaf, Nicki; Chu, Julia S.; Ma, Hong; Boyer, Eric; van Gool, Frederic; Huang, Hailiang; Liu, Ruize; Tobin, Victoria R.; Schumann, Kathrin; Daly, Mark J.; Farh, Kyle K.; Ansel, K. Mark; Ye, Chun J.; Greenleaf, William J.; Anderson, Mark S.; Bluestone, Jeffrey A.; Chang, Howard Y.; Corn, Jacob E.; Marson, Alexander

    2017-09-01

    The majority of genetic variants associated with common human diseases map to enhancers, non-coding elements that shape cell-type-specific transcriptional programs and responses to extracellular cues. Systematic mapping of functional enhancers and their biological contexts is required to understand the mechanisms by which variation in non-coding genetic sequences contributes to disease. Functional enhancers can be mapped by genomic sequence disruption, but this approach is limited to the subset of enhancers that are necessary in the particular cellular context being studied. We hypothesized that recruitment of a strong transcriptional activator to an enhancer would be sufficient to drive target gene expression, even if that enhancer was not currently active in the assayed cells. Here we describe a discovery platform that can identify stimulus-responsive enhancers for a target gene independent of stimulus exposure. We used tiled CRISPR activation (CRISPRa) to synthetically recruit a transcriptional activator to sites across large genomic regions (more than 100 kilobases) surrounding two key autoimmunity risk loci, CD69 and IL2RA. We identified several CRISPRa-responsive elements with chromatin features of stimulus-responsive enhancers, including an IL2RA enhancer that harbours an autoimmunity risk variant. Using engineered mouse models, we found that sequence perturbation of the disease-associated Il2ra enhancer did not entirely block Il2ra expression, but rather delayed the timing of gene activation in response to specific extracellular signals. Enhancer deletion skewed polarization of naive T cells towards a pro-inflammatory T helper (TH17) cell state and away from a regulatory T cell state. This integrated approach identifies functional enhancers and reveals how non-coding variation associated with human immune dysfunction alters context-specific gene programs.

  1. Discovery of stimulation-responsive immune enhancers with CRISPR activation

    Science.gov (United States)

    Simeonov, Dimitre R.; Gowen, Benjamin G.; Boontanrart, Mandy; Roth, Theodore L.; Gagnon, John D.; Mumbach, Maxwell R.; Satpathy, Ansuman T.; Lee, Youjin; Bray, Nicolas L.; Chan, Alice Y.; Lituiev, Dmytro S.; Nguyen, Michelle L.; Gate, Rachel E.; Subramaniam, Meena; Li, Zhongmei; Woo, Jonathan M.; Mitros, Therese; Ray, Graham J.; Curie, Gemma L.; Naddaf, Nicki; Chu, Julia S.; Ma, Hong; Boyer, Eric; Van Gool, Frederic; Huang, Hailiang; Liu, Ruize; Tobin, Victoria R.; Schumann, Kathrin; Daly, Mark J.; Farh, Kyle K; Ansel, K. Mark; Ye, Chun J.; Greenleaf, William J.; Anderson, Mark S.; Bluestone, Jeffrey A.; Chang, Howard Y.; Corn, Jacob E.; Marson, Alexander

    2017-01-01

    The majority of genetic variants associated with common human diseases map to enhancers, non-coding elements that shape cell-type-specific transcriptional programs and responses to extracellular cues1–3. Systematic mapping of functional enhancers and their biological contexts is required to understand the mechanisms by which variation in non-coding genetic sequences contributes to disease. Functional enhancers can be mapped by genomic sequence disruption4–6, but this approach is limited to the subset of enhancers that are necessary in the particular cellular context being studied. We hypothesized that recruitment of a strong transcriptional activator to an enhancer would be sufficient to drive target gene expression, even if that enhancer was not currently active in the assayed cells. Here we describe a discovery platform that can identify stimulus-responsive enhancers for a target gene independent of stimulus exposure. We used tiled CRISPR activation (CRISPRa)7 to synthetically recruit a transcriptional activator to sites across large genomic regions (more than 100 kilobases) surrounding two key autoimmunity risk loci, CD69 and IL2RA. We identified several CRISPRa-responsive elements with chromatin features of stimulus-responsive enhancers, including an IL2RA enhancer that harbours an autoimmunity risk variant. Using engineered mouse models, we found that sequence perturbation of the disease-associated Il2ra enhancer did not entirely block Il2ra expression, but rather delayed the timing of gene activation in response to specific extracellular signals. Enhancer deletion skewed polarization of naive T cells towards a pro-inflammatory T helper (TH17) cell state and away from a regulatory T cell state. This integrated approach identifies functional enhancers and reveals how non-coding variation associated with human immune dysfunction alters context-specific gene programs. PMID:28854172

  2. Mid-latitude Geomagnetic Field Analysis Using BOH Magnetometer: Preliminary Results

    Directory of Open Access Journals (Sweden)

    Junga Hwang

    2011-09-01

    Full Text Available Korea Astronomy and Space Science Institute researchers have installed and operated magnetometers at Mt. Bohyun Observatory to measure the Earth's magnetic field variations in South Korea. We, in 2007, installed a fluxgate magnetometer (RFP-523C to measure H, D, and Z components of the geomagnetic field. In addition, in 2009, we installed a Overhauser proton sensor to measure the absolute total magnetic field F and a three-axis magneto-impedance sensor for spectrum analysis. Currently three types of magnetometer data have been accumulated. In this paper, we provide the preliminary and the first statistical analysis using the BOH magnetometer installed at Mt. Bohyun Observatory. By superposed analysis, we find that daily variations of H, D, and Z shows similar tendency, that is, about 30 minutes before the meridian (11:28 a minimum appears and the time after about 3 hours and 30 minutes (15:28 a maximum appears. Also, a quiet interval start time (19:06 is near the sunset time, and a quiet interval end time (06:40 is near the sunrise time. From the sunset to the sunrise, the value of H has a nearly constant interval, that is, the sun affects the changes in H values. Seasonal variations show similar dependences to the sun. Local time variations show that noon region has the biggest variations and midnight region has the smallest variations. We compare the correlations between geomagnetic variations and activity indices as we expect the geomagnetic variation would contain the effects of geomagnetic activity variations. As a result, the correlation coefficient between H and Dst is the highest (r = 0.947, and other AL, AE, AU index and showed a high correlation. Therefore, the effects of geomagnetic storms and geomagnetic substorms might contribute to the geomagnetic changes significantly.

  3. Analysis of Total Electron Content and Electron Density Profile during Different Geomagnetic Storms

    Science.gov (United States)

    Chapagain, N. P.; Rana, B.; Adhikari, B.

    2017-12-01

    Total Electron content (TEC) and electron density are the key parameters in the mitigation of ionospheric effects on radio communication system. Detail study of the TEC and electron density variations has been carried out during geomagnetic storms, with longitude and latitude, for four different locations: (13˚N -17˚N, 88˚E -98˚E), (30˚N-50˚N, 120˚W -95˚W), (29˚S-26˚S, 167˚W-163˚W,) and (60˚S-45˚S, 120˚W-105˚W) using the Gravity Recovery and Climate Experiment (GRACE) satellite observations. In order to find the geomagnetic activity, the solar wind parameters such as north-south component of inter planetary magnetic field (Bz), plasma drift velocity (Vsw), flow pressure (nPa), AE, Dst and Kp indices were obtained from Operating Mission as Nodes on the Internet (OMNI) web system. The data for geomagnetic indices have been correlated with the TEC and electron density for four different events of geomagnetic storms on 6 April 2008, 27 March 2008, 4 September 2008, and 11 October 2008. The result illustrates that the observed TEC and electron density profile significantly vary with longitudes and latitudes. This study illustrates that the values of TEC and the vertical electron density profile are influenced by the solar wind parameters associated with solar activities. The peak values of electron density and TEC increase as the geomagnetic storms become stronger. Similarly, the electron density profile varies with altitudes, which peaks around the altitude range of about 250- 350 km, depending on the strength of geomagnetic storms. The results clearly show that the peak electron density shifted to higher altitude (from about 250 km to 350 km) as the geomagnetic disturbances becomes stronger.

  4. Geomagnetism during solar cycle 23: Characteristics

    Directory of Open Access Journals (Sweden)

    Jean-Louis Zerbo

    2013-05-01

    Full Text Available On the basis of more than 48 years of morphological analysis of yearly and monthly values of the sunspot number, the aa index, the solar wind speed and interplanetary magnetic field, we point out the particularities of geomagnetic activity during the period 1996–2009. We especially investigate the last cycle 23 and the long minimum which followed it. During this period, the lowest values of the yearly averaged IMF (3 nT and yearly averaged solar wind speed (364 km/s are recorded in 1996, and 2009 respectively. The year 2003 shows itself particular by recording the highest value of the averaged solar wind (568 km/s, associated to the highest value of the yearly averaged aa index (37 nT. We also find that observations during the year 2003 seem to be related to several coronal holes which are known to generate high-speed wind stream. From the long time (more than one century study of solar variability, the present period is similar to the beginning of twentieth century. We especially present the morphological features of solar cycle 23 which is followed by a deep solar minimum.

  5. Is Enhanced Physical Activity Possible Using Active Videogames?

    Science.gov (United States)

    Baranowski, Tom; Baranowski, Janice; O'Connor, Teresia; Lu, Amy Shirong; Thompson, Debbe

    2012-06-01

    Our research indicated that 10-12-year-old children receiving two active Wii ™ (Nintendo ® ; Nintendo of America, Inc., Redmond, WA) console videogames were no more physically active than children receiving two inactive videogames. Research is needed on how active videogames may increase physical activity.

  6. Is Enhanced Physical Activity Possible Using Active Videogames?

    OpenAIRE

    Baranowski, Tom; Baranowski, Janice; O'Connor, Teresia; Lu, Amy Shirong; Thompson, Debbe

    2012-01-01

    Our research indicated that 10–12-year-old children receiving two active Wii™ (Nintendo®; Nintendo of America, Inc., Redmond, WA) console videogames were no more physically active than children receiving two inactive videogames. Research is needed on how active videogames may increase physical activity.

  7. Geomagnetically conjugate observations of ionospheric and thermospheric variations accompanied with a midnight brightness wave at low latitudes

    Science.gov (United States)

    Fukushima, D.; Shiokawa, K.; Otsuka, Y.; Kubota, M.; Yokoyama, T.; Nishioka, M.; Komonjinda, S.; Yatini, C. Y.

    2014-12-01

    A midnight brightness wave (MBW) is the phenomenon that the OI (630-nm) airglow enhancement propagates poleward once at local midnight. In this study, we first conducted geomagnetically conjugate observations of 630nm airglow for an MBW at conjugate stations. An airglow enhancement which is considered to be an MBW was observed in the 630-nm airglow images at Kototabang, Indonesia (geomagnetic latitude (MLAT): 10.0S) at around local midnight from 1540 to 1730 UT (from 2240 to 2430 LT) on 7 February 2011. This MBW was propagating south-southwestward, which is geomagnetically poleward, with a velocity of 290 m/s. However, similar wave was not observed in the 630-nm airglow images at Chiang Mai, Thailand (MLAT: 8.9N), which is close to being conjugate point of Kototabang. This result indicates that the MBW does not have geomagnetic conjugacy. We simultaneously observed thermospheric neutral winds observed by a co-located Fabry-Perot interferometer at Kototabang. The observed meridional winds turned from northward (geomagnetically equatorward) to southward (geomagnetically poleward) just before the MBW was observed. The bottomside ionospheric heights observed by ionosondes rapidly decreased at Kototabang and slightly increased at Chiang Mai simultaneously with the MBW passage. In the presentation, we discuss the MBW generation by the observed poleward neutral winds at Kototabang, and the cause of the coinciding small height increase at Chiang Mai by the polarization electric field inside the observed MBW at Kototabang.

  8. Surface enhanced Raman optical activity (SEROA)

    DEFF Research Database (Denmark)

    Abdali, Salim; Blanch, E.W.

    2008-01-01

    Raman optical activity (ROA) directly monitors the stereochemistry of chiral molecules and is now an incisive probe of biomolecular structure. ROA spectra contain a wealth of information on tertiary folding, secondary structure and even the orientation of individual residues in proteins and nucleic...

  9. Enhancement of immunological activity after mild hyperthermia

    International Nuclear Information System (INIS)

    Noguchi, Kenichi; Hasegawa, Takeo; Takahashi, Tohru

    2002-01-01

    At present, hyperthermia is clinically very important as interdisciplinary therapeutic method, and studies are being performed on combined effects with surgical treatment, radiotherapy, chemotherapy and gene therapy for the treatment of malignant tumors. We evaluated the effects of hyperthermia under temperature of 42.5C and demonstrated that the activation of immunological response is increased and anti-tumor effect cabn be obtained in this studies. We used animals were C3H mice (male,7W) bearing SCC-VII tumor on femur skin. Then, the mice were divided to 10 mice in each group, and only femur region was immersed in warm water for thermal treatment. Also we measured the tumor growth, changes of blood cell fraction and NK cell activity. The results of the present study confirmed: (1) Anti-tumor effect can be given by thermal treatment at relatively mild temperature (mild temperature at 39C-42C); (2) The increase of neutrophils is dependent on the quantity of heat added; (3) Immunological response of monocytes and lymphocytes is associated with it; (4) Activity of the immunological potency as a whole such as activation of NK cells was also confirmed

  10. Enhanced casein kinase II activity in human tumour cell cultures

    DEFF Research Database (Denmark)

    Prowald, K; Fischer, H; Issinger, O G

    1984-01-01

    Casein kinase II (CKII) activity is enhanced as much as 2-3 fold in established and 4-5-fold in transformed human cell lines when compared to that of fibroblasts and primary human tumour cell cultures where CKII activity never exceeded a basic level. The high activity of CKII in transformed cells...

  11. Geometric effects of ICMEs on geomagnetic storms

    Science.gov (United States)

    Cho, KyungSuk; Lee, Jae-Ok

    2017-04-01

    It has been known that the geomagnetic storm is occurred by the interaction between the Interplanetary Coronal Mass Ejection (ICME) and the Earth's magnetosphere; especially, the southward Bz component of ICME is thought as the main trigger. In this study, we investigate the relationship between Dst index and solar wind conditions; which are the southward Bz, electric field (VBz), and time integral of electric field as well as ICME parameters derived from toroidal fitting model in order to find what is main factor to the geomagnetic storm. We also inspect locations of Earth in ICMEs to understand the geometric effects of the Interplanetary Flux Ropes (IFRs) on the geomagnetic storms. Among 59 CDAW ICME lists, we select 30 IFR events that are available by the toroidal fitting model and classify them into two sub-groups: geomagnetic storms associated with the Magnetic Clouds (MCs) and the compression regions ahead of the MCs (sheath). The main results are as follows: (1) The time integral of electric field has a higher correlation coefficient (cc) with Dst index than the other parameters: cc=0.85 for 25 MC events and cc=0.99 for 5 sheath events. (2) The sheath associated intense storms (Dst ≤-100nT) having usually occur at flank regions of ICMEs while the MC associated intense storms occur regardless of the locations of the Earth in ICMEs. The strength of a geomagnetic storm strongly depends on electric field of IFR and durations of the IFR passages through the Earth.

  12. Relationship between human physiological parameters and geomagnetic variations of solar origin

    Science.gov (United States)

    Dimitrova, S.

    Results presented concern influence of increased geomagnetic activity on some human physiological parameters. The blood pressure and heart rate of 86 volunteers were measured on working days in autumn 2001 (01/10 09/11) and in spring 2002 (08/04 28/05). These periods were chosen because of maximal expected geomagnetic activity. Altogether 2799 recordings were obtained and analysed. Questionnaire information about subjective psycho-physiological complaints was also gathered. MANOVA was employed to check the significance of the influence of three factors on the physiological parameters under consideration. The factors were the following: (1) planetary geomagnetic activity level estimated by Ap-index and divided into five levels; (2) gender males and females; (3) blood pressure degree persons in the group examined were divided into hypotensive, normotensive and hypertensive. Post hoc analysis was performed to elicit the significance of differences in the factors’ levels. The average arterial blood pressure of the group was found to increase significantly with the increase of geomagnetic activity level. The average increment of systolic and diastolic blood pressure of the group examined reached 9%. This effect was present irrespectively of gender. Results obtained suppose that hypertensive persons have the highest sensitivity and the hypotensive persons have the lowest sensitivity of the arterial blood pressure to increase of geomagnetic activity. The results did not show significant changes in the heart rate. The percentage of the persons who reported subjective psycho-physiological complaints was also found to increase significantly with the geomagnetic activity increase and the highest sensitivity was revealed for the hypertensive females.

  13. The Running Wheel Enhances Food Anticipatory Activity: An Exploratory Study.

    Science.gov (United States)

    Flôres, Danilo E F L; Bettilyon, Crystal N; Jia, Lori; Yamazaki, Shin

    2016-01-01

    Rodents anticipate rewarding stimuli such as daily meals, mates, and stimulant drugs. When a single meal is provided daily at a fixed time of day, an increase in activity, known as food anticipatory activity (FAA), occurs several hours before feeding time. The factors affecting the expression of FAA have not been well-studied. Understanding these factors may provide clues to the undiscovered anatomical substrates of food entrainment. In this study we determined whether wheel-running activity, which is also rewarding to rodents, modulated the robustness of FAA. We found that access to a freely rotating wheel enhanced the robustness of FAA. This enhancement was lost when the wheel was removed. In addition, while prior exposure to a running wheel alone did not enhance FAA, the presence of a locked wheel did enhance FAA as long as mice had previously run in the wheel. Together, these data suggest that FAA, like wheel-running activity, is influenced by reward signaling.

  14. Study of the mid-latitude ionospheric response to geomagnetic storms in the European region

    Science.gov (United States)

    Berényi, Kitti Alexandra; Barta, Veronika; Kis, Arpad

    2016-07-01

    Geomagnetic storms affect the ionospheric regions of the terrestrial upper atmosphere through different physical and atmospheric processes. The phenomena that can be regarded as a result of these processes, generally is named as "ionospheric storm". The processes depend on altitude, segment of the day, the geomagnetic latitude and longitude, strength of solar activity and the type of the geomagnetic storm. We examine the data of ground-based radio wave ionosphere sounding measurements of European ionospheric stations (mainly the data of Nagycenk Geophysical Observatory) in order to determine how and to what extent a geomagnetic disturbance of a certain strength affects the mid-latitude ionospheric regions in winter and in summer. For our analysis we used disturbed time periods between November 2012 and June 2015. Our results show significant changing of the ionospheric F2 layer parameters on strongly disturbed days compared to quiet ones. We show that the critical frequencies (foF2) increase compared to their quiet day value when the ionospheric storm was positive. On the other hand, the critical frequencies become lower, when the storm was negative. In our analysis we determined the magnitude of these changes on the chosen days. For a more complete analysis we compare also the evolution of the F2 layer parameters of the European ionosonde stations on a North-South geographic longitude during a full storm duration. The results present the evolution of an ionospheric storm over a geographic meridian. Furthermore, we compared the two type of geomagnetic storms, namely the CME caused geomagnetic storm - the so-called Sudden impulse (Si) storms- and the HSS (High Speed Solar Wind Streams) caused geomagnetic storms -the so-called Gradual storms (Gs)- impact on the ionospheric F2-layer (foF2 parameter). The results show a significant difference between the effect of Si and of the Gs storms on the ionospheric F2-layer.

  15. Modeling of Thermospheric Neutral Density Variations in Response to Geomagnetic Forcing using GRACE Accelerometer Data

    Science.gov (United States)

    Calabia, A.; Matsuo, T.; Jin, S.

    2017-12-01

    The upper atmospheric expansion refers to an increase in the temperature and density of Earth's thermosphere due to increased geomagnetic and space weather activities, producing anomalous atmospheric drag on LEO spacecraft. Increased drag decelerates satellites, moving their orbit closer to Earth, decreasing the lifespan of satellites, and making satellite orbit determination difficult. In this study, thermospheric neutral density variations due to geomagnetic forcing are investigated from 10 years (2003-2013) of GRACE's accelerometer-based estimates. In order to isolate the variations produced by geomagnetic forcing, 99.8% of the total variability has been modeled and removed through the parameterization of annual, LST, and solar-flux variations included in the primary Empirical Orthogonal Functions. The residual disturbances of neutral density variations have been investigated further in order to unravel their relationship to several geomagnetic indices and space weather activity indicators. Stronger fluctuations have been found in the southern polar cap, following the dipole-tilt angle variations. While the parameterization of the residual disturbances in terms of Dst index results in the best fit to training data, the use of merging electric field as a predictor leads to the best forecasting performance. An important finding is that modeling of neutral density variations in response geomagnetic forcing can be improved by accounting for the latitude-dependent delay. Our data-driven modeling results are further compared to modeling with TIEGCM.

  16. Is enhanced physical activity possible using active videogames?

    Science.gov (United States)

    Our research indicated that 10– to 12-year-old children receiving two active Wii (TM)(Nintendo (R); Nintendo of America, Inc., Redmond, WA) console videogames were no more physically active than children receiving two inactive videogames. Research is needed on how active videogames may increase phys...

  17. Coronal mass ejections and large geomagnetic storms

    International Nuclear Information System (INIS)

    Gosling, J.T.; Bame, S.J.; McComas, D.J.; Phillips, J.L.

    1990-01-01

    Previous work indicates that coronal mass ejection (CME) events in the solar wind at 1 AU can be identified by the presence of a flux of counterstreaming solar wind halo electrons (above about 80 eV). Using this technique to identify CMEs in 1 AU plasma data, the authors find that most large geomagnetic storms during the interval surrounding the last solar maximum (Aug. 1978-Oct. 1982) were associated with Earth-passage of interplanetary disturbances in which the Earth encountered both a shock and the CME driving the shock. However, only about one CME in six encountered by Earth was effective in causing a large geomagnetic storm. Slow CMEs which did not interact strongly with the ambient solar wind ahead were particularly ineffective in a geomagnetic sense

  18. Geochemistry and Geochronology of Ngorongoro Crater, Tanzania: Implication for Magma Evolution, Duration of Volcanic Activity and Age of the Ngorongoro N-R Geomagnetic Polarity Transition

    Science.gov (United States)

    Mollel, G. F.; Swisher, C. C.; Feigenson, M. D.; Carr, M. J.

    2005-05-01

    40Ar/39Ar dates on volcanic rocks from the Ngorongoro Crater (NC) in northern Tanzania indicate that NC activity was very short in duration lasting approximately 120 ka. Laser incremental heating experiments on lava from the bottom and top of the NC crater-wall section gave ages of 2.08 +/- 0.04 and 1.96 +/- 0.02 Ma respectively. Lavas from the same section show a change in magnetic polarity from normal (N) at the lower part to reverse (R) polarity at the upper part (Grommé et al. 1970). The new ages are about 400 ka younger than previously estimated by K-Ar technique. These new ages suggest correlation of the NC N-R polarity transition to the 2.1 Ma (N-R) Reunion-Matuyama boundary (Cande and Kent, 1995), instead of the Gauss-Matuyama boundary as proposed by Grommé et al. (1970). 87Sr/86Sr measurements on lavas from the NC section vary widely from 0.70801 in the trachydacite at the base to 0.70405 in the basaltic lava near the top. The lower part of the section is more radiogenic varying from 0.70592 to 0.70801 whereas the upper part is constrained to 0.70405 to 0.70450. The more radiogenic lower part is likely to have interacted with crustal rocks. Two possible contaminants are the Tanzanian Archean Craton to the west and the late Proterozoic Mozambican belt in the east. The crater-wall section is composed of trachydacite at the bottom that becomes trachyandesite in mid-section. The top section is mainly basaltic. Major and trace elements show an inverted geochemical signature that is typical of stratified magma chambers characterized by a silicic top and basaltic bottom. Olivine basalt at the upper part of the section has the highest Mg# (56.60) and in general the upper section is more mafic than the lower section as inferred from Mg#. The upper part of the section is high in TiO2, MgO, FeOT, and CaO wt% whereas SiO2 and K2O wt% are higher in lower part of the section. No significant variations are observed in N2O, Al2O3, P2O5 and MnO wt% up-section. Highly

  19. Improvements in geomagnetic observatory data quality

    DEFF Research Database (Denmark)

    Reda, Jan; Fouassier, Danielle; Isac, Anca

    2011-01-01

    between observatories and the establishment of observatory networks has harmonized standards and practices across the world; improving the quality of the data product available to the user. Nonetheless, operating a highquality geomagnetic observatory is non-trivial. This article gives a record...... of the current state of observatory instrumentation and methods, citing some of the general problems in the complex operation of geomagnetic observatories. It further gives an overview of recent improvements of observatory data quality based on presentation during 11th IAGA Assembly at Sopron and INTERMAGNET...

  20. A simple statistical model for geomagnetic reversals

    Science.gov (United States)

    Constable, Catherine

    1990-01-01

    The diversity of paleomagnetic records of geomagnetic reversals now available indicate that the field configuration during transitions cannot be adequately described by simple zonal or standing field models. A new model described here is based on statistical properties inferred from the present field and is capable of simulating field transitions like those observed. Some insight is obtained into what one can hope to learn from paleomagnetic records. In particular, it is crucial that the effects of smoothing in the remanence acquisition process be separated from true geomagnetic field behavior. This might enable us to determine the time constants associated with the dominant field configuration during a reversal.

  1. Geomagnetic Storm Impact On GPS Code Positioning

    Science.gov (United States)

    Uray, Fırat; Varlık, Abdullah; Kalaycı, İbrahim; Öǧütcü, Sermet

    2017-04-01

    This paper deals with the geomagnetic storm impact on GPS code processing with using GIPSY/OASIS research software. 12 IGS stations in mid-latitude were chosen to conduct the experiment. These IGS stations were classified as non-cross correlation receiver reporting P1 and P2 (NONCC-P1P2), non-cross correlation receiver reporting C1 and P2 (NONCC-C1P2) and cross-correlation (CC-C1P2) receiver. In order to keep the code processing consistency between the classified receivers, only P2 code observations from the GPS satellites were processed. Four extreme geomagnetic storms October 2003, day of the year (DOY), 29, 30 Halloween Storm, November 2003, DOY 20, November 2004, DOY 08 and four geomagnetic quiet days in 2005 (DOY 92, 98, 99, 100) were chosen for this study. 24-hour rinex data of the IGS stations were processed epoch-by-epoch basis. In this way, receiver clock and Earth Centered Earth Fixed (ECEF) Cartesian Coordinates were solved for a per-epoch basis for each day. IGS combined broadcast ephemeris file (brdc) were used to partly compensate the ionospheric effect on the P2 code observations. There is no tropospheric model was used for the processing. Jet Propulsion Laboratory Application Technology Satellites (JPL ATS) computed coordinates of the stations were taken as true coordinates. The differences of the computed ECEF coordinates and assumed true coordinates were resolved to topocentric coordinates (north, east, up). Root mean square (RMS) errors for each component were calculated for each day. The results show that two-dimensional and vertical accuracy decreases significantly during the geomagnetic storm days comparing with the geomagnetic quiet days. It is observed that vertical accuracy is much more affected than the horizontal accuracy by geomagnetic storm. Up to 50 meters error in vertical component has been observed in geomagnetic storm day. It is also observed that performance of Klobuchar ionospheric correction parameters during geomagnetic storm

  2. Geomagnetic response to sudden expansions of the magnetosphere

    International Nuclear Information System (INIS)

    Araki, Tohru; Nagano, Hiroshi

    1988-01-01

    The geomagnetic response to five successive sudden expansions of the magnetosphere was examined by the use of magnetic data observed on the ground and by satellites. At the geosynchronous orbit between 0800 and 1100 LT the magnetic field component parallel to Earth's rotation axis decreased successively. The amplitude and the fall time of each decrease were 20-30 nT and 2.5-3.5 min, respectively. The decrease was propagated about 10 min later to the distance of about 31 R E from Earth in the antisunward direction, indicating propagation speed of about 300 km/s. The H component of ground magnetograms from low-latitude stations showed decreases with waveform similar to that at the geosynchronous orbit, but each decrease at the dayside equator was greatly enhanced and preceded by a short small positive impulse. Each of the corresponding geomagnetic variations at high latitude stations consisted of two successive sharp pulses of opposite sense with 2-3 min duration. The dominant component and the sense of these high-latitude pulses were highly dependent upon local time and latitude. The distribution of equivalent ionospheric current arrows for each high-latitude pulse showed clear twin vortices centered at 70-76 degree geomagnetic latitude in the dayside and was approximately symmetric with respect to the noon meridian. The current direction of the vortices was reversed from the first pulse to the second. it suggests successive appearance of a dawn-to-dusk and then a dusk-to-dawn electric field, both of which were transmitted from the magnetosphere to the polar ionosphere. The effect of ionospheric currents due to these polar electric fields was superposed on the simple magnetic decrease produced by an expansion of the whole magnetosphere and produced the complex waveform distribution on the ground

  3. A superposed epoch analysis of geomagnetic storms

    Directory of Open Access Journals (Sweden)

    J. R. Taylor

    1994-06-01

    Full Text Available A superposed epoch analysis of geomagnetic storms has been undertaken. The storms are categorised via their intensity (as defined by the Dst index. Storms have also been classified here as either storm sudden commencements (SSCs or storm gradual commencements (SGCs, that is all storms which did not begin with a sudden commencement. The prevailing solar wind conditions defined by the parameters solar wind speed (vsw, density (ρsw and pressure (Psw and the total field and the components of the interplanetary magnetic field (IMF during the storms in each category have been investigated by a superposed epoch analysis. The southward component of the IMF, appears to be the controlling parameter for the generation of small SGCs (-100 nT< minimum Dst ≤ -50 nT for ≥ 4 h, but for SSCs of the same intensity solar wind pressure is dominant. However, for large SSCs (minimum Dst ≤ -100 nT for ≥ 4 h the solar wind speed is the controlling parameter. It is also demonstrated that for larger storms magnetic activity is not solely driven by the accumulation of substorm activity, but substantial energy is directly input via the dayside. Furthermore, there is evidence that SSCs are caused by the passage of a coronal mass ejection, whereas SGCs result from the passage of a high speed/ slow speed coronal stream interface. Storms are also grouped by the sign of Bz during the first hour epoch after the onset. The sign of Bz at t = +1 h is the dominant sign of the Bz for ~24 h before the onset. The total energy released during storms for which Bz was initially positive is, however, of the same order as for storms where Bz was initially negative.

  4. Analysis of the positive ionospheric response to a moderate geomagnetic storm using a global numerical model

    Directory of Open Access Journals (Sweden)

    A. A. Namgaladze

    2000-04-01

    Full Text Available Current theories of F-layer storms are discussed using numerical simulations with the Upper Atmosphere Model, a global self-consistent, time dependent numerical model of the thermosphere-ionosphere-plasmasphere-magnetosphere system including electrodynamical coupling effects. A case study of a moderate geomagnetic storm at low solar activity during the northern winter solstice exemplifies the complex storm phenomena. The study focuses on positive ionospheric storm effects in relation to thermospheric disturbances in general and thermospheric composition changes in particular. It investigates the dynamical effects of both neutral meridional winds and electric fields caused by the disturbance dynamo effect. The penetration of short-time electric fields of magnetospheric origin during storm intensification phases is shown for the first time in this model study. Comparisons of the calculated thermospheric composition changes with satellite observations of AE-C and ESRO-4 during storm time show a good agreement. The empirical MSISE90 model, however, is less consistent with the simulations. It does not show the equatorward propagation of the disturbances and predicts that they have a gentler latitudinal gradient. Both theoretical and experimental data reveal that although the ratio of [O]/[N2] at high latitudes decreases significantly during the magnetic storm compared with the quiet time level, at mid to low latitudes it does not increase (at fixed altitudes above the quiet reference level. Meanwhile, the ionospheric storm is positive there. We conclude that the positive phase of the ionospheric storm is mainly due to uplifting of ionospheric F2-region plasma at mid latitudes and its equatorward movement at low latitudes along geomagnetic field lines caused by large-scale neutral wind circulation and the passage of travelling atmospheric disturbances (TADs. The calculated zonal electric field disturbances also help to create the positive ionospheric

  5. Analysis of the positive ionospheric response to a moderate geomagnetic storm using a global numerical model

    Directory of Open Access Journals (Sweden)

    A. A. Namgaladze

    Full Text Available Current theories of F-layer storms are discussed using numerical simulations with the Upper Atmosphere Model, a global self-consistent, time dependent numerical model of the thermosphere-ionosphere-plasmasphere-magnetosphere system including electrodynamical coupling effects. A case study of a moderate geomagnetic storm at low solar activity during the northern winter solstice exemplifies the complex storm phenomena. The study focuses on positive ionospheric storm effects in relation to thermospheric disturbances in general and thermospheric composition changes in particular. It investigates the dynamical effects of both neutral meridional winds and electric fields caused by the disturbance dynamo effect. The penetration of short-time electric fields of magnetospheric origin during storm intensification phases is shown for the first time in this model study. Comparisons of the calculated thermospheric composition changes with satellite observations of AE-C and ESRO-4 during storm time show a good agreement. The empirical MSISE90 model, however, is less consistent with the simulations. It does not show the equatorward propagation of the disturbances and predicts that they have a gentler latitudinal gradient. Both theoretical and experimental data reveal that although the ratio of [O]/[N2] at high latitudes decreases significantly during the magnetic storm compared with the quiet time level, at mid to low latitudes it does not increase (at fixed altitudes above the quiet reference level. Meanwhile, the ionospheric storm is positive there. We conclude that the positive phase of the ionospheric storm is mainly due to uplifting of ionospheric F2-region plasma at mid latitudes and its equatorward movement at low latitudes along geomagnetic field lines caused by large-scale neutral wind circulation and the passage of travelling atmospheric disturbances (TADs. The calculated zonal electric field disturbances also help

  6. Regional corrections and checking the reliability of geomagnetic forecasts

    International Nuclear Information System (INIS)

    Afanas'eva, V.I.; Shevnin, A.D.

    1978-01-01

    Regional corrections of the K index mark estimate with respect to the Moskva observatory are reviewed in order to improve the short-range forecast of the geomagnetic activity and to promote it within the aqua area. The forecasts of the storms of all categories and weak perturbations have been verified for the predominant days in the catalogue of the magnetic storms family. It is shown that the adopted methods of forecasts yield considerably good results for weak perturbations as well as for weak and moderate magnetic storms. Strong and very strong storms are less predictable

  7. Local time and cutoff rigidity dependences of storm time increase associated with geomagnetic storms

    International Nuclear Information System (INIS)

    Kudo, S.; Wada, M.; Tanskanen, P.; Kodama, M.

    1987-01-01

    The cosmic ray increases due to considerable depressions of cosmic ray cutoff rigidity during large geomagnetic storms are investigated. Data from a worldwide network of cosmic ray neutron monitors are analyzed for 17 geomagnetic storms which occurred in the quiet phase of the solar activity cycle during 1966-1978. As expected from the longitudinal asymmetry of the low-altitude geomagnetic field during large geomagnetic storms, a significant local time dependence of the increment in the cosmic ray during large geomagnetic storms, a significant local time dependence of the increment in the cosmic ray intensity is obtained. It is shown that the maximum phases of the local time dependence occur at around 1800 LT and that the amplitudes of the local time dependence are consistent with presently available theoretical estimates. The dependence of the increment on the cutoff rigidity is obtained for both the local time dependent part and the local time independent part of the storm time increase. The local time independent part, excluding the randomizing local time dependent part, shows a clear-cut dependence on cutoff rigidity which is consistent with theoretical estimates

  8. Geomagnetic storms, super-storms, and their impacts on GPS-based navigation systems

    Science.gov (United States)

    Astafyeva, E.; Yasyukevich, Yu.; Maksikov, A.; Zhivetiev, I.

    2014-07-01

    Using data of GPS receivers located worldwide, we analyze the quality of GPS performance during four geomagnetic storms of different intensity: two super-storms and two intense storms. We show that during super-storms the density of GPS Losses-of-Lock (LoL) increases up to 0.25% at L1 frequency and up to 3% at L2 frequency, and up to 0.15% (at L1) and 1% (at L2) during less intense storms. Also, depending on the intensity of the storm time ionospheric disturbances, the total number of total electron content (TEC) slips can exceed from 4 to 40 times the quiet time level. Both GPS LoL and TEC slips occur during abrupt changes of SYM-H index of geomagnetic activity, i.e., during the main phase of geomagnetic storms and during development of ionospheric storms. The main contribution in the total number of GPS LoL was found to be done by GPS sites located at low and high latitudes, whereas the area of numerous TEC slips seemed to mostly correspond to the boundary of the auroral oval, i.e., region with intensive ionospheric irregularities. Our global maps of TEC slips show where the regions with intense irregularities of electron density occur during geomagnetic storms and will let us in future predict appearance of GPS errors for geomagnetically disturbed conditions.

  9. Environmental Education Activities to Enhance Decision-Making.

    Science.gov (United States)

    Yambert, Paul A.; And Others

    This document contains a set of 10 activities that teachers may use with students (ages 10 to adult) to enhance environmental knowledge and environmentally responsible behavior. Sample worksheets are included when applicable. The activities focus on: renewable and nonrenewable resources; recycling; population growth; wildlife; recycling in a…

  10. Geomagnetically conjugate observations of ionospheric and thermospheric variations accompanied by a midnight brightness wave at low latitudes

    Science.gov (United States)

    Fukushima, D.; Shiokawa, K.; Otsuka, Y.; Kubota, M.; Yokoyama, T.; Nishioka, M.; Komonjinda, S.; Yatini, C. Y.

    2017-08-01

    We conducted geomagnetically conjugate observations of 630-nm airglow for a midnight brightness wave (MBW) at Kototabang, Indonesia [geomagnetic latitude (MLAT): 10.0°S], and Chiang Mai, Thailand (MLAT: 8.9°N), which are geomagnetically conjugate points at low latitudes. An airglow enhancement that was considered to be an MBW was observed in OI (630-nm) airglow images at Kototabang around local midnight from 2240 to 2430 LT on February 7, 2011. This MBW propagated south-southwestward, which is geomagnetically poleward, at a velocity of 290 m/s. However, a similar wave was not observed in the 630-nm airglow images at Chiang Mai. This is the first evidence of an MBW that does not have geomagnetic conjugacy, which also implies generation of MBW only in one side of the hemisphere from the equator. We simultaneously observed thermospheric neutral winds observed by a co-located Fabry-Perot interferometer at Kototabang. The observed meridional winds turned from northward (geomagnetically equatorward) to southward (geomagnetically poleward) just before the wave was observed. This indicates that the observed MBW was generated by the poleward winds which push ionospheric plasma down along geomagnetic field lines, thereby increasing the 630-nm airglow intensity. The bottomside ionospheric heights observed by ionosondes rapidly decreased at Kototabang and slightly increased at Chiang Mai. We suggest that the polarization electric field inside the observed MBW is projected to the northern hemisphere, causing the small height increase observed at Chiang Mai. This implies that electromagnetic coupling between hemispheres can occur even though the original disturbance is caused purely by the neutral wind.[Figure not available: see fulltext.

  11. Geological support for the Umbrella Effect as a link between geomagnetic field and climate

    Science.gov (United States)

    Kitaba, Ikuko; Hyodo, Masayuki; Nakagawa, Takeshi; Katoh, Shigehiro; Dettman, David L.; Sato, Hiroshi

    2017-01-01

    The weakening of the geomagnetic field causes an increase in galactic cosmic ray (GCR) flux. Some researchers argue that enhanced GCR flux might lead to a climatic cooling by increasing low cloud formation, which enhances albedo (umbrella effect). Recent studies have reported geological evidence for a link between weakened geomagnetic field and climatic cooling. However, more work is needed on the mechanism of this link, including whether the umbrella effect is playing a central role. In this research, we present new geological evidence that GCR flux change had a greater impact on continental climate than on oceanic climate. According to pollen data from Osaka Bay, Japan, the decrease in temperature of the Siberian air mass was greater than that of the Pacific air mass during geomagnetic reversals in marine isotope stages (MIS) 19 and 31. Consequently, the summer land-ocean temperature gradient was smaller, and the summer monsoon was weaker. Greater terrestrial cooling indicates that a reduction of insolation is playing a key role in the link between the weakening of the geomagnetic field and climatic cooling. The most likely candidate for the mechanism seems to be the increased albedo of the umbrella effect. PMID:28091595

  12. A synoptic study of geomagnetic storms and related solar phenomena during 1976 through 1978

    International Nuclear Information System (INIS)

    Marubashi, K.

    1979-01-01

    An attempt has been made to identify the causes of geomagnetic storms which occurred during the three year period from 1976 through 1978. Of the 114 storms with D sub(st) = 25 investigated in this paper, 52 storms are found to be caused by corotating streams, 16 storms by solar flares, and 19 storms by compound effects of both corotating streams and flares. The causes of the remaining 27 storms could not be identified. By examining the characteristics of those solar flares which were taken to be responsible for geomagnetic storms, a semiquantitative conclusion has been obtained about the criteria for the flares which can produce magnetic storms. In addition, clear semiannual variation has been found in geomagnetic activity caused by flare-free corotating streams. (author)

  13. Geomagnetic and ionospheric data analysis over Antarctica: a contribution to the long term trends investigation

    Directory of Open Access Journals (Sweden)

    L. Alfonsi

    2008-05-01

    Full Text Available The analysis of the foF2 ionosonde data acquired at mid and high latitudes reveals a general decreasing of the F2 plasma frequency over more than two solar cycles, showing steeper trends over the high latitude stations and, in particular, over Antarctica. A careful analysis of the foF2 hourly data, opportunely catalogued in different levels of magneto-ionospheric conditions, highlights the role of the geomagnetic activity in the secular change of the ionosphere and confirms the latitudinal dependence of the trends. These results suggest interesting relations with some recent findings on the rapid decrease of some important physical and statistical quantities related to the geomagnetic field over the whole globe and mainly in Antarctica. In this paper we discuss the possibility of a connection between the ionospheric trends and a possible imminent geomagnetic reversal or excursion.

  14. Geomagnetic and ionospheric data analysis over Antarctica: a contribution to the long term trends investigation

    Directory of Open Access Journals (Sweden)

    L. Alfonsi

    2008-05-01

    Full Text Available The analysis of the foF2 ionosonde data acquired at mid and high latitudes reveals a general decreasing of the F2 plasma frequency over more than two solar cycles, showing steeper trends over the high latitude stations and, in particular, over Antarctica. A careful analysis of the foF2 hourly data, opportunely catalogued in different levels of magneto-ionospheric conditions, highlights the role of the geomagnetic activity in the secular change of the ionosphere and confirms the latitudinal dependence of the trends. These results suggest interesting relations with some recent findings on the rapid decrease of some important physical and statistical quantities related to the geomagnetic field over the whole globe and mainly in Antarctica. In this paper we discuss the possibility of a connection between the ionospheric trends and a possible imminent geomagnetic reversal or excursion.

  15. Geomagnetic secular variation at the African observatories

    International Nuclear Information System (INIS)

    Haile, T.

    2002-10-01

    Geomagnetic data from ten observatories in the African continent with time series data length of more than three decades have been analysed. All-day annual mean values of the D, H and Z components were used to study secular variations in the African region. The residuals in D, H and Z components obtained after removing polynomial fits have been examined in relation to the sunspot cycle. The occurrence of the 1969-1970 worldwide geomagnetic impulse in each observatory is studied. It is found that the secular variation in the field can be represented for most of the observatories with polynomials of second or third degree. Departures from these trends are observed over the Southern African region where strong local magnetic anomalies have been observed. The residuals in the geomagnetic field components have been shown to exhibit parallelism with the periods corresponding to double solar cycle for some of the stations. A clear latitudinal distribution in the geomagnetic component that exhibits the 1969-70 jerk is shown. The jerk appears in the plots of the first differences in H for the southern most observatories of Hermanus, Hartebeesthoek, and Tsuemb, while the Z plots show the jerk for near equatorial and equatorial stations of Antananarivo, Luanda Belas, Bangui and Addis Ababa. There is some indication for this jerk in the first difference plots of D for the northern stations of M'Bour and Tamanrasset. The plots of D rather strongly suggest the presence of a jerk around 1980 at most of the stations. (author)

  16. Some aspects of geomagnetically conjugate phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Rycroft, M.J.

    1987-12-01

    Both charged particles and waves convey information about the thermosphere, ionosphere and magnetosphere from the Northern to the Southern Hemisphere and vice versa, along geomagnetic flux tubes.The interhemispheric travel time of electrons or ions, being dependent upon L-value , pitch angle and energy (which may lie between less than or equal to 1 eV and greater than or equal to 1 MeV) may be many hours, ranging down to less than or equal to 1 s. However, the one-hop propagation time for magnetohydrodynamic or whistler mode waves generally lies between 10/sup 2/s and 1 s. Such times, therefore, give the time scales of transient phenomena that are geomagnetically conjugate and of changes in steady-state plasma processes occurring in geomagnetically conjugate regions. Contrasting examples are presented of conjugate physical phenomena, obtained using satellite, rocket, aircraft and ground-based observations; the latter capitalise upon the rather rare disposition of land - rather than ocean - at each end of a geophysically interesting flux tube. Particular attention is paid to the interactions between whistler mode waves and energetic electrons. Geomagnetic, radio, optical and plasma observations, taken together with model computations, provide a wealth of knowledge on conjugate phenomena and their dependence on conditions in the solar wind, substorms, L-value, etc... Finally, some suggestions are made for future lines of research.

  17. Dynamical similarity of geomagnetic field reversals.

    Science.gov (United States)

    Valet, Jean-Pierre; Fournier, Alexandre; Courtillot, Vincent; Herrero-Bervera, Emilio

    2012-10-04

    No consensus has been reached so far on the properties of the geomagnetic field during reversals or on the main features that might reveal its dynamics. A main characteristic of the reversing field is a large decrease in the axial dipole and the dominant role of non-dipole components. Other features strongly depend on whether they are derived from sedimentary or volcanic records. Only thermal remanent magnetization of lava flows can capture faithful records of a rapidly varying non-dipole field, but, because of episodic volcanic activity, sequences of overlying flows yield incomplete records. Here we show that the ten most detailed volcanic records of reversals can be matched in a very satisfactory way, under the assumption of a common duration, revealing common dynamical characteristics. We infer that the reversal process has remained unchanged, with the same time constants and durations, at least since 180 million years ago. We propose that the reversing field is characterized by three successive phases: a precursory event, a 180° polarity switch and a rebound. The first and third phases reflect the emergence of the non-dipole field with large-amplitude secular variation. They are rarely both recorded at the same site owing to the rapidly changing field geometry and last for less than 2,500 years. The actual transit between the two polarities does not last longer than 1,000 years and might therefore result from mechanisms other than those governing normal secular variation. Such changes are too brief to be accurately recorded by most sediments.

  18. Gramicidin D enhances the antibacterial activity of fluoride

    OpenAIRE

    Nelson, James W.; Zhou, Zhiyuan; Breaker, Ronald R.

    2014-01-01

    Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in B. subtilis and that the antibacterial activity of this compound...

  19. Qualitative and quantitative estimations of the effect of geomagnetic field variations on human brain functional state

    International Nuclear Information System (INIS)

    Belisheva, N.K.; Popov, A.N.; Petukhova, N.V.; Pavlova, L.P.; Osipov, K.S.; Tkachenko, S.Eh.; Baranova, T.I.

    1995-01-01

    The comparison of functional dynamics of human brain with reference to qualitative and quantitative characteristics of local geomagnetic field (GMF) variations was conducted. Steady and unsteady states of human brain can be determined: by geomagnetic disturbances before the observation period; by structure and doses of GMF variations; by different combinations of qualitative and quantitative characteristics of GMF variations. Decrease of optimal GMF activity level and the appearance of aperiodic disturbances of GMF can be a reason of unsteady brain's state. 18 refs.; 3 figs

  20. Local geomagnetic events associated with displacements on the san andreas fault.

    Science.gov (United States)

    Breiner, S; Kovach, R L

    1967-10-06

    The piezomagnetic properties of rock suggest that a change in subsurface stress will manifest itself as a change in the magnetic susceptibility and remanent magnetization and hence the local geomagnetic field. A differential array of magnetometers has been operating since late 1965 on the San Andreas fault in the search for piezomagnetic signals under conditions involving active fault stress. Local changes in the geomagnetic field have been observed near Hollister, California, some tens of hours preceding the onset of abrupt creep displacement on the San Andreas fault.

  1. Evaluation of geomagnetic storm effects on the GPS derived Total Electron Content (TEC)

    International Nuclear Information System (INIS)

    Purohit, P K; Atulkar, Roshni; Mansoori, Azad A; Khan, Parvaiz A; Bhawre, Purushottam; Tripathi, Sharad C; Khatarkar, Prakash; Bhardwaj, Shivangi; Aslam, A M; Waheed, Malik A; Gwal, A K

    2015-01-01

    The geomagnetic storm represents the most outstanding example of solar wind- magnetospheric interaction, which causes global disturbances in the geomagnetic field as well as triggers ionospheric disturbances. We study the behaviour of ionospheric Total Electron Content (TEC) during the geomagnetic storms. For this investigation we have selected 47 intense geomagnetic storms (Dst ≤ -100nT) that were observed during the solar cycle 23 i.e. during 1998- 2006. We then categorized these storms into four categories depending upon their solar sources like Magnetic Cloud (MC), Co-rotating Interaction Region (CIR), SH+ICME and SH+MC. We then studied the behaviour of ionospheric TEC at a mid latitude station Usuda (36.13N, 138.36E), Japan during these storm events produced by four different solar sources. During our study we found that the smooth variations in TEC are replaced by rapid fluctuations and the value of TEC is strongly enhanced during the time of these storms belonging to all the four categories. However, the greatest enhancements in TEC are produced during those geomagnetic storms which are either caused by Sheath driven Magnetic cloud (SH+MC) or Sheath driven ICME (SH+ICME). We also derived the correlation between the TEC enhancements produced during storms of each category with the minimum Dst. We found the strongest correlation exists for the SH+ICME category followed by SH+MC, MC and finally CIR. Since the most intense storms were either caused by SH+ICME or SH+MC while the least intense storms were caused by CIR, consequently the correlation was strongest with SH+ICME and SH+MC and least with CIR. (paper)

  2. What do we mean by accuracy in geomagnetic measurements?

    Science.gov (United States)

    Green, A.W.

    1990-01-01

    High accuracy is what distinguishes measurements made at the world's magnetic observatories from other types of geomagnetic measurements. High accuracy in determining the absolute values of the components of the Earth's magnetic field is essential to studying geomagnetic secular variation and processes at the core mantle boundary, as well as some magnetospheric processes. In some applications of geomagnetic data, precision (or resolution) of measurements may also be important. In addition to accuracy and resolution in the amplitude domain, it is necessary to consider these same quantities in the frequency and space domains. New developments in geomagnetic instruments and communications make real-time, high accuracy, global geomagnetic observatory data sets a real possibility. There is a growing realization in the scientific community of the unique relevance of geomagnetic observatory data to the principal contemporary problems in solid Earth and space physics. Together, these factors provide the promise of a 'renaissance' of the world's geomagnetic observatory system. ?? 1990.

  3. Sub-ionospheric VLF signal anomaly due to geomagnetic storms: a statistical study

    Directory of Open Access Journals (Sweden)

    K. Tatsuta

    2015-11-01

    Full Text Available We investigate quantitatively the effect of geomagnetic storms on the sub-ionospheric VLF/LF (Very Low Frequency/Low Frequency propagations for different latitudes based on 2-year nighttime data from Japanese VLF/LF observation network. Three statistical parameters such as average signal amplitude, variability of the signal amplitude, and nighttime fluctuation were calculated daily for 2 years for 16–21 independent VLF/LF transmitter–receiver propagation paths consisting of three transmitters and seven receiving stations. These propagation paths are suitable to simultaneously study high-latitude, low-mid-latitude and mid-latitude D/E-region ionospheric properties. We found that these three statistical parameters indicate significant anomalies exceeding at least 2 times of their standard deviation from the mean value during the geomagnetic storm time period in the high-latitude paths with an occurrence rate of anomaly between 40 and 50 % presumably due to the auroral energetic electron precipitation. The mid-latitude and low-mid-latitude paths have a smaller influence from the geomagnetic activity because of a lower occurrence rate of anomalies even during the geomagnetically active time period (from 20 to 30 %. The anomalies except geomagnetic storm periods may be caused by atmospheric and/or lithospheric origins. The statistical occurrence rates of ionospheric anomalies for different latitudinal paths during geomagnetic storm and non-storm time periods are basic and important information not only to identify the space weather effects toward the lower ionosphere depending on the latitudes but also to separate various external physical causes of lower ionospheric disturbances.

  4. Geomagnetic field evolution during the Laschamp excursion

    Science.gov (United States)

    Leonhardt, Roman; Fabian, Karl; Winklhofer, Michael; Ferk, Annika; Laj, Carlo; Kissel, Catherine

    2009-02-01

    Since the last geomagnetic reversal, 780,000 years ago, the Earth's magnetic field repeatedly dropped dramatically in intensity. This has often been associated with large variations in local field direction, but without a persistent global polarity flip. The structure and dynamics of geomagnetic excursions, and especially the difference between excursions and polarity reversals, have remained elusive so far. For the best documented excursion, the Laschamp event at 41,000 years BP, we have reconstructed the evolution of the global field morphology by using a Bayesian inversion of several high-resolution palaeomagnetic records. We have obtained an excursion scenario in which inverse magnetic flux patches at the core-mantle boundary emerge near the equator and then move poleward. Contrary to the situation during the last reversal (Leonhardt, R., Fabian, K., 2007. Paleomagnetic reconstruction of the global geomagnetic field evolution during the Matuyama/Brunhes transition: Iterative Bayesian inversion and independent verification. Earth Planet. Sci. Lett. 253, 172-195), these flux patches do not cross the hydrodynamic boundary of the inner-core tangent cylinder. While the last geomagnetic reversal began with a substantial increase in the strength of the non-dipolar field components, prior to the Laschamp excursion, both dipolar and non-dipolar field decay at the same rate. This result suggests that the nature of an upcoming geomagnetic field instability can be predicted several hundred years in advance. Even though during the Laschamp excursion the dipolar field at the Earth's surface was dominant, the reconstructed dynamic non-dipolar components lead to considerable deviations among predicted records at different locations. The inverse model also explains why at some locations no directional change during the Laschamp excursion is observed.

  5. Ficus Deltoidea Enhance Glucose Uptake Activity in Cultured Muscle Cells

    International Nuclear Information System (INIS)

    Zainah Adam; Shafii Khamis; Amin Ismail; Muhajir Hamid

    2015-01-01

    Ficus deltoidea or locally known as Mas cotek is one of the common medicinal plants used in Malaysia. Our previous studies showed that this plant have blood glucose lowering effect. Glucose uptake into muscle and adipocytes cells is one of the known mechanisms of blood glucose lowering effect. This study was performed to evaluate the effect of Ficus deltoidea on glucose uptake activity into muscle cells. The cells were incubated with Ficus deltoidea extracts either alone or combination with insulin. Amount of glucose uptake by L6 myotubes was determined using glucose tracer, 2-deoxy-(1- 3 H 1 )-glucose. The results showed that Ficus deltoidea extracts at particular doses enhanced basal or insulin-mediated glucose uptake into muscle cells significantly. Hot aqueous extract enhanced glucose uptake at the low concentration (10 μg/ ml) whereas methanolic extract enhanced glucose uptake at low and high concentrations. Methanolic extract also mimicked insulin activity during enhancing glucose uptake into L^ muscle cells. Glucose uptake activity of Ficus deltoidea could be attributed by the phenolic compound presence in the plant. This study had shown that Ficus deltoidea has the ability to enhance glucose uptake into muscle cells which is partly contributed the antidiabetic activity of this plant. (author)

  6. K-type geomagnetic index nowcast with data quality control

    Directory of Open Access Journals (Sweden)

    René Warnant

    2011-07-01

    Full Text Available

    A nowcast system for operational estimation of a proxy K-type geomagnetic index is presented. The system is based on a fully automated computer procedure for real-time digital magnetogram data acquisition that includes screening of the dataset and removal of the outliers, estimation of the solar regular variation (SR of the geomagnetic field, calculation of the index, and issuing of an alert if storm-level activity is indicated. This is a time-controlled (rather than event-driven system that delivers the regular output of: the index value, the estimated quality flag, and eventually, an alert. The novel features provided are first, the strict control of the data input and processing, and second, the increased frequency of production of the index (every 1 h. Such quality control and increased time resolution have been found to be of crucial importance for various applications, e.g. ionospheric monitoring, that are of particular interest to us and to users of our service. The nowcast system operability, accuracy and precision have been tested with instantaneous measurements from recent years. A statistical comparison between the nowcast and the definitive index values shows that the average root-mean-square error is smaller than 1 KU. The system is now operational at the site of the Geophysical Centre of the Royal Meteorological Institute in Dourbes (50.1ºN, 4.6ºE, and it is being used for alerting users when geomagnetic storms take place.

  7. The use of various interplanetary scintillation indices within geomagnetic forecasts

    Directory of Open Access Journals (Sweden)

    E. A. Lucek

    Full Text Available Interplanetary scintillation (IPS, the twinkling of small angular diameter radio sources, is caused by the interaction of the signal with small-scale plasma irregularities in the solar wind. The technique may be used to sense remotely the near-Earth heliosphere and observations of a sufficiently large number of sources may be used to track large-scale disturbances as they propagate from close to the Sun to the Earth. Therefore, such observations have potential for use within geomagnetic forecasts. We use daily data from the Mullard Radio Astronomy Observatory, made available through the World Data Centre, to test the success of geomagnetic forecasts based on IPS observations. The approach discussed here was based on the reduction of the information in a map to a single number or series of numbers. The advantages of an index of this nature are that it may be produced routinely and that it could ideally forecast both the occurrence and intensity of geomagnetic activity. We start from an index that has already been described in the literature, INDEX35. On the basis of visual examination of the data in a full skymap format modifications were made to the way in which the index was calculated. It was hoped that these would lead to an improvement in its forecasting ability. Here we assess the forecasting potential of the index using the value of the correlation coefficient between daily Ap and the IPS index, with IPS leading by 1 day. We also compare the forecast based on the IPS index with forecasts of Ap currently released by the Space Environment Services Center (SESC. Although we find that the maximum improvement achieved is small, and does not represent a significant advance in forecasting ability, the IPS forecasts at this phase of the solar cycle are of a similar quality to those made by SESC.

  8. Change of the radiocarbon natural level in the Earth atmosphere and geomagnetic field

    International Nuclear Information System (INIS)

    Vasil'ev, S.S.; Dergachev, V.A.

    1995-01-01

    Harmonic spectral analysis of change of radiocarbon concentration on the Earth atmosphere during the last 7000 years, including time intervals of both high and low intensity of the Earth magnetic field, was conducted. The effect of geomagnetic field on a harmonic amplitudes and frequencies in variations of radiocarbon concentration, conditioned by solar activity, was shown

  9. Space weather and dangerous phenomena on the Earth: principles of great geomagnetic storms forcasting by online cosmic ray data

    Directory of Open Access Journals (Sweden)

    L. I. Dorman

    2005-11-01

    Full Text Available According to NOAA space weather scales, geomagnetic storms of scales G5 (3-h index of geomagnetic activity Kp=9, G4 (Kp=8 and G3 (Kp=7 are dangerous for satellites, aircrafts, and even for technology on the ground (influence on power systems, on spacecraft operations, on HF radio-communications and others. We show on the basis of statistical data, that these geomagnetic storms, mostly accompanied by cosmic ray (CR Forbush-decreases, are also dangerous for people's health on spacecraft and on the ground (increasing the rate of myocardial infarctions, brain strokes and car accident road traumas. To prevent these serious damages it is very important to forecast dangerous geomagnetic storms. Here we consider the principles of using CR measurements for this aim: to forecast at least 10-15h before the sudden commencement of great geomagnetic storms accompanied by Forbush-decreases, by using neutron monitor muon telescope worldwide network online hourly data. We show that for this forecast one may use the following features of CR intensity variations connected with geomagnetic storms accompanied by Forbush-decreases: 1 CR pre-increase, 2 CR pre-decrease, 3 CR fluctuations, 4 change in the 3-D CR anisotropy.

  10. The influence of meteorological and geomagnetic factors on acute myocardial infarction and brain stroke in Moscow, Russia.

    Science.gov (United States)

    Shaposhnikov, Dmitry; Revich, Boris; Gurfinkel, Yuri; Naumova, Elena

    2014-07-01

    Evidence of the impact of air temperature and pressure on cardiovascular morbidity is still quite limited and controversial, and even less is known about the potential influence of geomagnetic activity. The objective of this study was to assess impacts of air temperature, barometric pressure and geomagnetic activity on hospitalizations with myocardial infarctions and brain strokes. We studied 2,833 myocardial infarctions and 1,096 brain strokes registered in two Moscow hospitals between 1992 and 2005. Daily event rates were linked with meteorological and geomagnetic conditions, using generalized linear model with controls for day of the week, seasonal and long-term trends. The number of myocardial infarctions decreased with temperature, displayed a U-shaped relationship with pressure and variations in pressure, and increased with geomagnetic activity. The number of strokes increased with temperature, daily temperature range and geomagnetic activity. Detrimental effects on strokes of low pressure and falling pressure were observed. Relative risks of infarctions and strokes during geomagnetic storms were 1.29 (95% CI 1.19-1.40) and 1.25 (1.10-1.42), respectively. The number of strokes doubled during cold spells. The influence of barometric pressure on hospitalizations was relatively greater than the influence of geomagnetic activity, and the influence of temperature was greater than the influence of pressure. Brain strokes were more sensitive to inclement weather than myocardial infarctions. This paper provides quantitative estimates of the expected increases in hospital admissions on the worst days and can help to develop preventive health plans for cardiovascular diseases.

  11. Chimeric polypeptides having cellulolytic enhancing activity and polynucleotides encoding same

    Science.gov (United States)

    Wogulis, Mark; Sweeney, Matthew; Heu, Tia

    2017-06-14

    The present invention relates to chimeric GH61 polypeptides having cellulolytic enhancing activity. The present invention also relates to polynucleotides encoding the chimeric GH61 polypeptides; nucleic acid constructs, vectors, and host cells comprising the polynucleotides; and methods of using the chimeric GH61 polypeptides.

  12. Activity enhancement of ligninolytic enzymes of Trametes versicolor ...

    African Journals Online (AJOL)

    Suspended cultures of white-rot fungus, Trametes versicolor, supplemented with bagasse powder showed a concentration dependent enhancement in the ligninolytic enzymes activity in liquid shake cultures. 2% (w/v) bagasse powder improved greater stability to the enzymes. The optimum pH is 3.5 and the optimum ...

  13. Polypeptides having cellulolytic enhancing activity and polynucleotides encoding same

    Science.gov (United States)

    Maiyuran, Suchindra; Kramer, Randall; Harris, Paul

    2013-10-29

    The present invention relates to isolated polypeptides having cellulolytic enhancing activity and isolated polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.

  14. Can aquatic worms enhance methane production from waste activated sludge?

    NARCIS (Netherlands)

    Serrano, Antonio; Hendrickx, Tim L.G.; Elissen, Hellen; Laarhoven, Bob; Buisman, Cees J.N.; Temmink, Hardy

    2016-01-01

    Although literature suggests that aquatic worms can help to enhance the methane production from excess activated sludge, clear evidence for this is missing. Therefore, anaerobic digestion tests were performed at 20 and at 30 °C with sludge from a high-loaded membrane bioreactor, the aquatic worm

  15. The geomagnetic cutoff rigidities at high latitudes for different solar wind and geomagnetic conditions

    International Nuclear Information System (INIS)

    Chu, W.; Univ. of Chinese Academy of Sciences, Beijing; Qin, G.

    2016-01-01

    Studying the access of the cosmic rays (CRs) into the magnetosphere is important to understand the coupling between the magnetosphere and the solar wind. In this paper we numerically studied CRs' magnetospheric access with vertical geomagnetic cutoff rigidities using the method proposed by Smart and Shea (1999). By the study of CRs' vertical geomagnetic cutoff rigidities at high latitudes we obtain the CRs' window (CRW) whose boundary is determined when the vertical geomagnetic cutoff rigidities drop to a value lower than a threshold value. Furthermore, we studied the area of CRWs and found out they are sensitive to different parameters, such as the z component of interplanetary magnetic field (IMF), the solar wind dynamic pressure, AE index, and Dst index. It was found that both the AE index and Dst index have a strong correlation with the area of CRWs during strong geomagnetic storms. However, during the medium storms, only AE index has a strong correlation with the area of CRWs, while Dst index has a much weaker correlation with the area of CRWs. This result on the CRW can be used for forecasting the variation of the cosmic rays during the geomagnetic storms.

  16. Geographical localisation of the geomagnetic secular variation

    DEFF Research Database (Denmark)

    Aubert, Julien; Finlay, Chris; Olsen, Nils

    2013-01-01

    the model and geomagnetic data previously processed in the same way. Our results suggest that conservation of angular momentum and heterogeneous thermochemical boundary control in the coupled inner core / outer core / mantle system are central to understanding how Earth’s magnetic field currently evolves......., westward moving, magnetic flux patches at the core surface. Despite its successes in explaining the main morphological properties of Earth’s magnetic field, self-consistent numerical modelling of the geodynamo has so far failed to reproduce this field variation pattern. Furthermore its magnetohydrodynamic...... control from either, or both, the inner-core boundary and the core-mantle boundary. In addition to presenting an Earth-like magnetic field morphology, these new numerical models also reproduce the morphology and localization of geomagnetic secular variation. In our models, the conservation of the angular...

  17. Mathematical Properties Relevant to Geomagnetic Field Modeling

    DEFF Research Database (Denmark)

    Sabaka, Terence J.; Hulot, Gauthier; Olsen, Nils

    2010-01-01

    be directly measured. In this chapter, the mathematical foundation of global (as opposed to regional) geomagnetic field modeling is reviewed, and the spatial modeling of the field in spherical coordinates is focussed. Time can be dealt with as an independent variable and is not explicitly considered......Geomagnetic field modeling consists in converting large numbers of magnetic observations into a linear combination of elementary mathematical functions that best describes those observations.The set of numerical coefficients defining this linear combination is then what one refers.......The relevant elementary mathematical functions are introduced, their properties are reviewed, and how they can be used to describe the magnetic field in a source-free (such as the Earth’s neutral atmosphere) or source-dense (such as the ionosphere) environment is explained. Completeness and uniqueness...

  18. Mathematical Properties Relevant to Geomagnetic Field Modeling

    DEFF Research Database (Denmark)

    Sabaka, Terence J.; Hulot, Gauthier; Olsen, Nils

    2014-01-01

    be directly measured. In this chapter, the mathematical foundation of global (as opposed to regional) geomagnetic field modeling is reviewed, and the spatial modeling of the field in spherical coordinates is focused. Time can be dealt with as an independent variable and is not explicitly considered......Geomagnetic field modeling consists in converting large numbers of magnetic observations into a linear combination of elementary mathematical functions that best describes those observations. The set of numerical coefficients defining this linear combination is then what one refers....... The relevant elementary mathematical functions are introduced, their properties are reviewed, and how they can be used to describe the magnetic field in a source-free (such as the Earth’s neutral atmosphere) or source-dense (such as the ionosphere) environment is explained. Completeness and uniqueness...

  19. Geomagnetic oriented electromagnetic radiation in the ionosphere

    International Nuclear Information System (INIS)

    Benton, C.U.; Fowles, H.M.; Goen, P.K.

    1976-08-01

    Strong bursts of electromagnetic radiation were observed in the ionosphere during the Waso rocket Electromagnetic Pulse (EMP) experiment. The pulses have a frequency content from below 20 MHz to above 70 MHz. They vary in duration between 5 μs and 2 ms and in peak-amplitudes of 2 mV/m to greater than 200 mV/m. These pulses show a high degree of geomagnetic correlation and are of unknown origin

  20. Geomagnetic fluctuations during a polarity transition

    Science.gov (United States)

    Audunsson, Haraldur; Levi, Shaul

    1997-01-01

    The extensive Roza Member of the Columbia River Basalt Group (Washington State) has intermediate paleomagnetic directions, bracketed by underlying normal and overlying reverse polarity flows. A consistent paleomagnetic direction was measured at 11 widely distributed outcrops; the average direction has a declination of 189° and an inclination of -5°, with greater variation in the inclination [Rietman, 1966]. In this study the Roza Member was sampled in two Pasco Basin drillcores, where it is a single cooling unit and its thickness exceeds 50 m. Excellent core recovery allowed uniform and dense sampling of the drillcores. During its protracted cooling, the Roza flow in the drillcores recorded part of a 15.5 Ma geomagnetic polarity transition. The inclination has symmetric, quasicyclic intraflow variation, while the declination is nearly constant, consistent with the results from the outcrops. Thermal models of the cooling flow provide the timing for remanence acquisition. The inclination is inferred to have progressed from 0° to -15° and back to -3°over a period of 15 to 60 years, at rates of 1.6° to 0.5°/yr. Because the geomagnetic intensity was probably weak during the transition, these apparently high rates of change are not significantly different from present-day secular variation. These results agree with the hypothesis that normal secular variation persists through geomagnetic transitions. The Iow-amplitude quasicyclical fluctuations of the field over tens of years, recorded by Roza, suggest that the geomagnetic field reverses in discrete steps, and that more than 15-60 years were required to complete this reversal.

  1. Uncertainty Quantification in Geomagnetic Field Modeling

    Science.gov (United States)

    Chulliat, A.; Nair, M. C.; Alken, P.; Meyer, B.; Saltus, R.; Woods, A.

    2017-12-01

    Geomagnetic field models are mathematical descriptions of the various sources of the Earth's magnetic field, and are generally obtained by solving an inverse problem. They are widely used in research to separate and characterize field sources, but also in many practical applications such as aircraft and ship navigation, smartphone orientation, satellite attitude control, and directional drilling. In recent years, more sophisticated models have been developed, thanks to the continuous availability of high quality satellite data and to progress in modeling techniques. Uncertainty quantification has become an integral part of model development, both to assess the progress made and to address specific users' needs. Here we report on recent advances made by our group in quantifying the uncertainty of geomagnetic field models. We first focus on NOAA's World Magnetic Model (WMM) and the International Geomagnetic Reference Field (IGRF), two reference models of the main (core) magnetic field produced every five years. We describe the methods used in quantifying the model commission error as well as the omission error attributed to various un-modeled sources such as magnetized rocks in the crust and electric current systems in the atmosphere and near-Earth environment. A simple error model was derived from this analysis, to facilitate usage in practical applications. We next report on improvements brought by combining a main field model with a high resolution crustal field model and a time-varying, real-time external field model, like in NOAA's High Definition Geomagnetic Model (HDGM). The obtained uncertainties are used by the directional drilling industry to mitigate health, safety and environment risks.

  2. Modeling the ocean effect of geomagnetic storms

    DEFF Research Database (Denmark)

    Olsen, Nils; Kuvshinov, A.

    2004-01-01

    At coastal sites, geomagnetic variations for periods shorter than a few days are strongly distorted by the conductivity of the nearby sea-water. This phenomena, known as the ocean (or coast) effect, is strongest in the magnetic vertical component. We demonstrate the ability to predict the ocean...... if the oceans are considered. Our analysis also indicates a significant local time asymmetry (i.e., contributions from spherical harmonics other than P-I(0)), especially during the main phase of the storm....

  3. Elliptical magnetic clouds and geomagnetic storms

    Czech Academy of Sciences Publication Activity Database

    Antoniadou, I.; Geranios, A.; Vandas, Marek; Panagopoulou, M.; Zacharopoulou, O.; Malandraki, O.

    2008-01-01

    Roč. 56, 3-4 (2008), s. 492-500 ISSN 0032-0633 R&D Projects: GA AV ČR 1QS300120506; GA ČR GA205/06/0875 Institutional research plan: CEZ:AV0Z10030501 Keywords : magnetic clouds * geomagnetic storms * solar wind Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.506, year: 2008

  4. Domino model for geomagnetic field reversals.

    Science.gov (United States)

    Mori, N; Schmitt, D; Wicht, J; Ferriz-Mas, A; Mouri, H; Nakamichi, A; Morikawa, M

    2013-01-01

    We solve the equations of motion of a one-dimensional planar Heisenberg (or Vaks-Larkin) model consisting of a system of interacting macrospins aligned along a ring. Each spin has unit length and is described by its angle with respect to the rotational axis. The orientation of the spins can vary in time due to spin-spin interaction and random forcing. We statistically describe the behavior of the sum of all spins for different parameters. The term "domino model" in the title refers to the interaction among the spins. We compare the model results with geomagnetic field reversals and dynamo simulations and find strikingly similar behavior. The aggregate of all spins keeps the same direction for a long time and, once in a while, begins flipping to change the orientation by almost 180 degrees (mimicking a geomagnetic reversal) or to move back to the original direction (mimicking an excursion). Most of the time the spins are aligned or antialigned and deviate only slightly with respect to the rotational axis (mimicking the secular variation of the geomagnetic pole with respect to the geographic pole). Reversals are fast compared to the times in between and they occur at random times, both in the model and in the case of the Earth's magnetic field.

  5. AI techniques in geomagnetic storm forecasting

    Science.gov (United States)

    Lundstedt, Henrik

    This review deals with how geomagnetic storms can be predicted with the use of Artificial Intelligence (AI) techniques. Today many different Al techniques have been developed, such as symbolic systems (expert and fuzzy systems) and connectionism systems (neural networks). Even integrations of AI techniques exist, so called Intelligent Hybrid Systems (IHS). These systems are capable of learning the mathematical functions underlying the operation of non-linear dynamic systems and also to explain the knowledge they have learned. Very few such powerful systems exist at present. Two such examples are the Magnetospheric Specification Forecast Model of Rice University and the Lund Space Weather Model of Lund University. Various attempts to predict geomagnetic storms on long to short-term are reviewed in this article. Predictions of a month to days ahead most often use solar data as input. The first SOHO data are now available. Due to the high temporal and spatial resolution new solar physics have been revealed. These SOHO data might lead to a breakthrough in these predictions. Predictions hours ahead and shorter rely on real-time solar wind data. WIND gives us real-time data for only part of the day. However, with the launch of the ACE spacecraft in 1997, real-time data during 24 hours will be available. That might lead to the second breakthrough for predictions of geomagnetic storms.

  6. Geomagnetic storm under laboratory conditions: randomized experiment

    Science.gov (United States)

    Gurfinkel, Yu I.; Vasin, A. L.; Pishchalnikov, R. Yu; Sarimov, R. M.; Sasonko, M. L.; Matveeva, T. A.

    2017-10-01

    The influence of the previously recorded geomagnetic storm (GS) on human cardiovascular system and microcirculation has been studied under laboratory conditions. Healthy volunteers in lying position were exposed under two artificially created conditions: quiet (Q) and storm (S). The Q regime playbacks a noise-free magnetic field (MF) which is closed to the natural geomagnetic conditions on Moscow's latitude. The S regime playbacks the initially recorded 6-h geomagnetic storm which is repeated four times sequentially. The cardiovascular response to the GS impact was assessed by measuring capillary blood velocity (CBV) and blood pressure (BP) and by the analysis of the 24-h ECG recording. A storm-to-quiet ratio for the cardio intervals (CI) and the heart rate variability (HRV) was introduced in order to reveal the average over group significant differences of HRV. An individual sensitivity to the GS was estimated using the autocorrelation function analysis of the high-frequency (HF) part of the CI spectrum. The autocorrelation analysis allowed for detection a group of subjects of study which autocorrelation functions (ACF) react differently in the Q and S regimes of exposure.

  7. Geomagnetic storm under laboratory conditions: randomized experiment.

    Science.gov (United States)

    Gurfinkel, Yu I; Vasin, A L; Pishchalnikov, R Yu; Sarimov, R M; Sasonko, M L; Matveeva, T A

    2018-04-01

    The influence of the previously recorded geomagnetic storm (GS) on human cardiovascular system and microcirculation has been studied under laboratory conditions. Healthy volunteers in lying position were exposed under two artificially created conditions: quiet (Q) and storm (S). The Q regime playbacks a noise-free magnetic field (MF) which is closed to the natural geomagnetic conditions on Moscow's latitude. The S regime playbacks the initially recorded 6-h geomagnetic storm which is repeated four times sequentially. The cardiovascular response to the GS impact was assessed by measuring capillary blood velocity (CBV) and blood pressure (BP) and by the analysis of the 24-h ECG recording. A storm-to-quiet ratio for the cardio intervals (CI) and the heart rate variability (HRV) was introduced in order to reveal the average over group significant differences of HRV. An individual sensitivity to the GS was estimated using the autocorrelation function analysis of the high-frequency (HF) part of the CI spectrum. The autocorrelation analysis allowed for detection a group of subjects of study which autocorrelation functions (ACF) react differently in the Q and S regimes of exposure.

  8. Statistical study of waves distribution in the inner magnetosphere using geomagnetic indices and solar wind parameters

    Science.gov (United States)

    Aryan, H.; Yearby, K.; Balikhin, M. A.; Krasnoselskikh, V.; Agapitov, O. V.

    2013-12-01

    The interaction of gyroresonant wave particles with chorus waves largely determine the dynamics of the Earth's radiation belts that effects the acceleration and loss of radiation belt electrons. The common approach is to present model waves distribution in the inner magnetosphere under different values of geomagnetic activity as expressed by the geomagnetic indices. However it is known that solar wind parameters such as bulk velocity (V) and density (n) are more effective in the control of high energy fluxes at the geostationary orbit. Therefore in the present study the set of parameters of the wave distribution is expanded to include the solar wind parameters in addition to the geomagnetic indices. The present study examines almost four years (01, January, 2004 to 29, September, 2007) of Cluster STAFF-SA, Double Star TC1 and OMNI data in order to present a combined model of wave magnetic field intensities for the chorus waves as a function of magnetic local time (MLT), L-shell (L*), geomagnetic activity, and solar wind velocity and density. Generally, the largest wave intensities are observed during average solar wind velocities (3006cm-3. On the other hand the wave intensity is lower and limited between 06:00 to 18:00 MLT for V700kms-1.

  9. Impacts of ionospheric electric fields on the GPS tropospheric delays during geomagnetic storms in Antarctica

    International Nuclear Information System (INIS)

    Suparta, W

    2017-01-01

    This paper aimed to overview the interaction of the thunderstorm with the ionospheric electric fields during major geomagnetic storms in Antarctica through the GPS tropospheric delays. For the purpose of study, geomagnetic activity and electric fields data for the period from 13 to 21 March 2015 representing the St. Patrick’s Day storm is analyzed. To strengthen the analysis, data for the period of 27 October to 1 st November 2003 representing for the Halloween storm is also compared. Our analysis showed that both geomagnetic storms were severe ( Ap ≥ 100 nT), where the intensity of Halloween storm is double compared to St. Patrick’s Day storm. For the ionospheric electric field, the peaks were dropped to -1.63 mV/m and -2.564 mV/m for St. Patrick and Halloween storms, respectively. At this time, the interplanetary magnetic field Bz component was significantly dropped to -17.31 nT with Ap > 150 nT (17 March 2015 at 19:20 UT) and -26.51 nT with Ap = 300 nT (29 October 2003 at 19:40 UT). For both geomagnetic storms, the electric field was correlated well with the ionospheric activity where tropospheric delays show a different characteristic. (paper)

  10. Gramicidin D enhances the antibacterial activity of fluoride.

    Science.gov (United States)

    Nelson, James W; Zhou, Zhiyuan; Breaker, Ronald R

    2014-07-01

    Fluoride is a toxic anion found in many natural environments. One of the major bacterial defenses against fluoride is the cell envelope, which limits passage of the membrane-impermeant fluoride anion. Accordingly, compounds that enhance the permeability of bacterial membranes to fluoride should also enhance fluoride toxicity. In this study, we demonstrate that the pore-forming antibiotic gramicidin D increases fluoride uptake in Bacillus subtilis and that the antibacterial activity of this compound is potentiated by fluoride. Polymyxin B, another membrane-targeting antibiotic with a different mechanism of action, shows no such improvement. These results, along with previous findings, indicate that certain compounds that destabilize bacterial cell envelopes can enhance the toxicity of fluoride. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. "A Separation Theorem of Active Management and Synthetic Enhanced Active Strategies"(in Japanese)

    OpenAIRE

    Takao Kobayashi; Seiji Minami

    2008-01-01

    We propose a Separation Theorem of Active Management. It asserts that in the so-called Enhanced Active Portfolio framework the efficient frontier is linear in the active return/active risk space, and one can separate the determination of optimal active portfolio weights from the determination of optimal leverage ratio. The risk preference of investors does not play any role in the former decision. The theorem holds under a fairly general set of conditions on portfolio restrictions. As such it...

  12. An impending geomagnetic transition? Hints from the past

    OpenAIRE

    Laj, Carlo; Kissel, Catherine

    2015-01-01

    The rapid decrease of the geomagnetic field intensity in the last centuries has led to speculations that an attempt to a reversal or an excursion might be under way. Here we investigate this hypothesis by examining past records of geomagnetic field intensity obtained from sedimentary cores and from the study of cosmogenic nuclides. The selected records describe geomagnetic changes with an unprecedented temporal resolution between 20 and 75 kyr B.P. We find that some aspects of the present-day...

  13. Geomagnetic Observatory Annual Means Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) / World Data Center, Boulder maintains an active database of...

  14. Investigation of the Effects of Solar and Geomagnetic Changes on the Total Electron Content: Mid-Latitude Region

    Science.gov (United States)

    Ulukavak, Mustafa; Yalcinkaya, Mualla

    2016-04-01

    The Global Positioning System (GPS) is used as an important tool for ionosphere monitoring and obtaining the Total Electron Content (TEC). GPS satellites, positioned in the Earth's orbit, are used as sensors to investigate the space weather conditions. In this study, solar and geomagnetic activity variations were investigated between the dates 1 March-30 June 2015 for the mid-latitude region. GPS-TEC variations were calculated for each selected International GNSS Service (IGS) station in Europe. GNSS data was obtained from Crustal Dynamics Data and Information System (CDDIS) archive. Solar and geomagnetic activity indices (Kp, F10.7 ve Dst) were obtained from the Oceanic and Atmospheric Administration (NOAA), the Canadian Space Weather Forecast Centre (CSWFC) and Data Analysis Center for geomagnetism and Space Magnetism Graduate School of Science, Kyoto University (WDC) archives. GPS-TEC variations were determined for the quiet periods of the solar and geomagnetic activities. GPS-TEC changes were then compared with respect to the quiet periods of the solar and geomagnetic activities. Global Ionosphere Maps (GIM) IONEX files, obtained from the IGS analysis center, was used to check the robustness of the GPS-TEC variations. The investigations revealed that it is possible to use the GPS-TEC data for monitoring the ionospheric disturbances.

  15. Enhancing learning in geosciences and water engineering via lab activities

    Science.gov (United States)

    Valyrakis, Manousos; Cheng, Ming

    2016-04-01

    This study focuses on the utilisation of lab based activities to enhance the learning experience of engineering students studying Water Engineering and Geosciences. In particular, the use of modern highly visual and tangible presentation techniques within an appropriate laboratory based space are used to introduce undergraduate students to advanced engineering concepts. A specific lab activity, namely "Flood-City", is presented as a case study to enhance the active engagement rate, improve the learning experience of the students and better achieve the intended learning objectives of the course within a broad context of the engineering and geosciences curriculum. Such activities, have been used over the last few years from the Water Engineering group @ Glasgow, with success for outreach purposes (e.g. Glasgow Science Festival and demos at the Glasgow Science Centre and Kelvingrove museum). The activity involves a specific setup of the demonstration flume in a sand-box configuration, with elements and activities designed so as to gamely the overall learning activity. Social media platforms can also be used effectively to the same goals, particularly in cases were the students already engage in these online media. To assess the effectiveness of this activity a purpose designed questionnaire is offered to the students. Specifically, the questionnaire covers several aspects that may affect student learning, performance and satisfaction, such as students' motivation, factors to effective learning (also assessed by follow-up quizzes), and methods of communication and assessment. The results, analysed to assess the effectiveness of the learning activity as the students perceive it, offer a promising potential for the use of such activities in outreach and learning.

  16. Enhanced supercapacitance of activated vertical graphene nanosheets in hybrid electrolyte

    Science.gov (United States)

    Ghosh, Subrata; Sahoo, Gopinath; Polaki, S. R.; Krishna, Nanda Gopala; Kamruddin, M.; Mathews, Tom

    2017-12-01

    Supercapacitors are becoming the workhorse for emerging energy storage applications due to their higher power density and superior cycle life compared to conventional batteries. The performance of supercapacitors depends on the electrode material, type of electrolyte, and interaction between them. Owing to the beneficial interconnected porous structure with multiple conducting channels, vertical graphene nanosheets (VGN) have proved to be leading supercapacitor electrode materials. Herein, we demonstrate a novel approach based on the combination of surface activation and a new organo-aqueous hybrid electrolyte, tetraethylammonium tetrafluoroborate in H2SO4, to achieve significant enhancement in supercapacitor performance of VGN. As-synthesized VGN exhibits an excellent supercapacitance of 0.64 mF/cm2 in H2SO4. However, identification of a novel electrolyte for performance enhancement is the subject of current research. The present manuscript demonstrates the potential of the hybrid electrolyte in enhancing the areal capacitance (1.99 mF/cm2) with excellent retention (only 5.4% loss after 5000 cycles) and Coulombic efficiency (93.1%). In addition, a five-fold enhancement in the capacitance of VGNs (0.64 to 3.31 mF/cm2) with a reduced internal resistance is achieved by the combination of KOH activation and the hybrid electrolyte.

  17. Near real-time geomagnetic data for space weather applications in the European sector

    Science.gov (United States)

    Johnsen, M. G.; Hansen, T. L.

    2012-12-01

    Tromsø Geophysical Observatory (TGO) is responsible for making and maintaining long time-series of geomagnetic measurements in Norway. TGO is currently operating 3 geomagnetic observatories and 11 variometer stations from southern Norway to Svalbard . Data from these 14 locations are acquired, processed and made available for the user community in near real-time. TGO is participating in several European Union (EU) and European Space Agency (ESA) space weather related projects where both near real-time data and derived products are provided. In addition the petroleum industry is benefiting from our real-time data services for directional drilling. Near real-time data from TGO is freely available for non-commercial purposes. TGO is exchanging data in near real-time with several institutions, enabling the presentation of near real-time geomagnetic data from more than 40 different locations in Fennoscandia and Greenland. The open exchange of non real-time geomagnetic data has been successfully going on for many years through services such as the world data center in Kyoto, SuperMAG, IMAGE and SPIDR. TGO's vision is to take this one step further and make the exchange of near real-time geomagnetic data equally available for the whole community. This presentation contains an overview of TGO, our activities and future aims. We will show how our near real-time data are presented. Our contribution to the space weather forecasting and nowcasting effort in the EU and ESA will be presented with emphasis on our real-time auroral activity index and brand new auroral activity monitor and electrojet tracker.

  18. Modafinil enhances thalamocortical activity by increasing neuronal electrotonic coupling

    Science.gov (United States)

    Urbano, Francisco J.; Leznik, Elena; Llinás, Rodolfo R.

    2007-01-01

    Modafinil (Provigil, Modiodal), an antinarcoleptic and mood-enhancing drug, is shown here to sharpen thalamocortical activity and to increase electrical coupling between cortical interneurons and between nerve cells in the inferior olivary nucleus. After irreversible pharmacological block of connexin permeability (i.e., by using either 18β-glycyrrhetinic derivatives or mefloquine), modafinil restored electrotonic coupling within 30 min. It was further established that this restoration is implemented through a Ca2+/calmodulin protein kinase II-dependent step. PMID:17640897

  19. Enhanced natural radiation exposure enhanced by human activity: the largest contributor to the Chinese population dose

    International Nuclear Information System (INIS)

    Pan Ziqiang; Liu Yanyang

    2011-01-01

    For the radiation exposure caused by human activities, the enhanced natural radiation exposure is the largest contributor to Chinese population dose. This problem has attracted social attention in recent years. Efforts have been made in several fields, such as radon indoors and in workplace, environmental problems associated with NORMs, occupational radiation hazards of non-uranium mine, and radiation dose evaluation for energy chain, but there are still many problems to be solved. In order to protect the health of workers and the public, while ensuring industrial production and economic development, it is also necessary to continue to strengthen research in all aspects above mentioned, and gradually promote the control of natural radiation exposure enhanced by human activities. (authors)

  20. Intelligent Architecture for Enhanced Observability for Active Distribution System

    DEFF Research Database (Denmark)

    Pokhrel, Basanta Raj; Nainar, Karthikeyan; Bak-Jensen, Birgitte

    2017-01-01

    There is a rapid increase of renewable energy resources (RE) and demand response resources (DRR) in the distribution networks. This is challenging for the reliable and stable operation of the grid. So, to ensure secure, optimized and economical operation in such active distribution grids they need...... for active distribution network which satisfies the need for higher observability reach with less field observation. Improved state estimation with composite load forecasting model is aimed for enhanced observability. This paper also summarizes the application of intelligent architecture in the operation...

  1. The Egyptian geomagnetic reference field to the Epoch, 2010.0

    Directory of Open Access Journals (Sweden)

    H.A. Deebes

    2017-06-01

    The geomagnetic anomaly maps, the normal geomagnetic field maps with their corresponding secular variation maps, the normal geomagnetic field equations of the geomagnetic elements (EGRF and their corresponding secular variations equations, are outlined. The anomalous sites, as discovered from the anomaly maps are, only, mentioned. In addition, a correlation between the International Geomagnetic Reference Field (IGRF 2010.0 and the Egyptian Geomagnetic Reference Field (EGRF 2010 is indicated.

  2. Mechanisms of morphine enhancement of spontaneous seizure activity.

    Science.gov (United States)

    Saboory, Ehsan; Derchansky, Miron; Ismaili, Mohammed; Jahromi, Shokrollah S; Brull, Richard; Carlen, Peter L; El Beheiry, Hossam

    2007-12-01

    High-dose opioid therapy can precipitate seizures; however, the mechanism of such a dangerous adverse effect remains poorly understood. The aim of our study was to determine whether the neuroexcitatory activity of high-dose morphine is mediated by selective stimulation of opioid receptors. Mice hippocampi were resected intact and bathed in low magnesium artificial cerebrospinal fluid to induce spontaneous seizure-like events recorded from CA1 neurons. Application of morphine had a biphasic effect on the recorded spontaneous seizure-like events. In a low concentration (10 microM), morphine depressed electrographic seizure activity. Higher morphine concentrations (30 and 100 microM) enhanced seizure activity in an apparent dose-dependent manner. Naloxone, a nonselective opiate antagonist blocked the proconvulsant action of morphine. Selective mu and kappa opiate receptor agonists and antagonists enhanced and suppressed the spontaneous seizure activity, respectively. On the contrary, delta opioid receptor ligands did not have an effect. The proseizure effect of morphine is mediated through selective stimulation of mu and kappa opiate receptors but not the activation of the delta receptor system. The observed dose-dependent mechanism of morphine neuroexcitation underscores careful adjustment and individualized opioid dosing in the clinical setting.

  3. Psychosocial Practices that Enhance Cognitive Activity in Dementia

    Directory of Open Access Journals (Sweden)

    Neslihan Lok

    2014-09-01

    Full Text Available The daily lives of individuals with dementia, cognitive aspects need to be strengthened in order to maintain the quality. For this reason, dementia, cognitive, psycho-social applications there is a need to increase activity. Dementia drug treatment interventions used as an aid to increase cognitive activity. These interventions, behavior, emotion, perception and stimulation-oriented approaches can be classified into four groups. Dementia cognitive enhancer activity and an older group, this intervention and dissemination practices for selecting the most appropriate method to be applied. All psychosocial practices to increase cognitive activity psychiatrist, psychiatric nurse specialists, psychologists, social workers, occupational therapists can with the condition to study the relevant therapy. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2014; 6(3.000: 210-216

  4. Detection of ULF geomagnetic signals associated with seismic events in Central Mexico using Discrete Wavelet Transform

    Directory of Open Access Journals (Sweden)

    O. Chavez

    2010-12-01

    Full Text Available The geomagnetic observatory of Juriquilla Mexico, located at longitude –100.45° and latitude 20.70°, and 1946 m a.s.l., has been operational since June 2004 compiling geomagnetic field measurements with a three component fluxgate magnetometer. In this paper, the results of the analysis of these measurements in relation to important seismic activity in the period of 2007 to 2009 are presented. For this purpose, we used superposed epochs of Discrete Wavelet Transform of filtered signals for the three components of the geomagnetic field during relative seismic calm, and it was compared with seismic events of magnitudes greater than Ms > 5.5, which have occurred in Mexico. The analysed epochs consisted of 18 h of observations for a dataset corresponding to 18 different earthquakes (EQs. The time series were processed for a period of 9 h prior to and 9 h after each seismic event. This data processing was compared with the same number of observations during a seismic calm. The proposed methodology proved to be an efficient tool to detect signals associated with seismic activity, especially when the seismic events occur in a distance (D from the observatory to the EQ, such that the ratio D/ρ < 1.8 where ρ is the earthquake radius preparation zone. The methodology presented herein shows important anomalies in the Ultra Low Frequency Range (ULF; 0.005–1 Hz, primarily for 0.25 to 0.5 Hz. Furthermore, the time variance (σ2 increases prior to, during and after the seismic event in relation to the coefficient D1 obtained, principally in the Bx (N-S and By (E-W geomagnetic components. Therefore, this paper proposes and develops a new methodology to extract the abnormal signals of the geomagnetic anomalies related to different stages of the EQs.

  5. Dynamics of the Solar Wind Electromagnetic Energy Transmission Into Magnetosphere during Large Geomagnetic Storms

    Science.gov (United States)

    Kuznetsova, Tamara; Laptukhov, Alexej; Petrov, Valery

    Causes of the geomagnetic activity (GA) in the report are divided into temporal changes of the solar wind parameters and the changes of the geomagnetic moment orientation relative directions of the solar wind electric and magnetic fields. Based on our previous study we concluded that a reconnection based on determining role of mutual orientation of the solar wind electric field and geomagnetic moment taking into account effects of the Earth's orbital and daily motions is the most effective compared with existing mechanisms. At present a reconnection as paradigma that has applications in broad fields of physics needs analysis of experimental facts to be developed. In terms of reconnection it is important not only mutual orientation of vectors describing physics of interaction region but and reconnection rate which depends from rate of energy flux to those regions where the reconnection is permitted. Applied to magnetosphere these regions first of all are dayside magnetopause and polar caps. Influence of rate of the energy flux to the lobe magnetopause (based on calculations of the Poyting electromagnetic flux component controlling the reconnection rate along the solar wind velocity Pv) on planetary GA (Dst, Kp indices) is investigated at different phases of geomagnetic storms. We study also the rate of energy flux to the polar caps during storms (based on calculations of the Poyting flux vector component along the geomagnetic moment Pm) and its influence on magnetic activity in the polar ionosphere: at the auroral zone (AU,AL indices). Results allow to evaluate contributions of high and low latitude sources of electromagnetic energy to the storm development and also to clear mechanism of the electromagnetic energy transmission from the solar wind to the magnetosphere. We evaluate too power of the solar wind electromagnetic energy during well-known large storms and compare result with power of the energy sources of other geophysical processes (atmosphere, ocean

  6. Dynamics of total electron content distribution during strong geomagnetic storms

    Science.gov (United States)

    Astafyeva, E. I.; Afraimovich, E. L.; Kosogorov, E. A.

    We worked out a new method of mapping of total electron content TEC equal lines displacement velocity The method is based on the technique of global absolute vertical TEC value mapping Global Ionospheric Maps technique GIM GIM with 2-hours time resolution are available from Internet underline ftp cddisa gsfc nasa gov in standard IONEX-files format We determine the displacement velocity absolute value as well as its wave vector orientation from increments of TEC x y derivatives and TEC time derivative for each standard GIM cell 5 in longitude to 2 5 in latitude Thus we observe global traveling of TEC equal lines but we also can estimate the velocity of these line traveling Using the new method we observed anomalous rapid accumulation of the ionosphere plasma at some confined area due to the depletion of the ionization at the other spacious territories During the main phase of the geomagnetic storm on 29-30 October 2003 very large TEC enhancements appeared in the southwest of North America TEC value in that area reached up to 200 TECU 1 TECU 10 16 m -2 It was found that maximal velocity of TEC equal lines motion exceeded 1500 m s and the mean value of the velocity was about 400 m s Azimuth of wave vectors of TEC equal lines were orientated toward the center of region with anomaly high values of TEC the southwest of North America It should be noted that maximal TEC values during geomagnetically quiet conditions is about 60-80 TECU the value of TEC equal lines

  7. Thrombopoietin contributes to enhanced platelet activation in cigarette smokers.

    Science.gov (United States)

    Lupia, Enrico; Bosco, Ornella; Goffi, Alberto; Poletto, Cesare; Locatelli, Stefania; Spatola, Tiziana; Cuccurullo, Alessandra; Montrucchio, Giuseppe

    2010-05-01

    Thrombopoietin (TPO) is a humoral growth factor that primes platelet activation in response to several agonists. We recently showed that TPO enhances platelet activation in unstable angina and sepsis. Aim of this study was to investigate the role of TPO in platelet function abnormalities described in cigarette smokers. In a case-control study we enrolled 20 healthy cigarette smokers and 20 nonsmokers, and measured TPO and C-reactive protein (CRP), as well as platelet-leukocyte binding and P-selectin expression. In vitro we evaluated the priming activity of smoker or control plasma on platelet activation, and the role of TPO in this effect. We then studied the effects of acute smoking and smoking cessation on TPO levels and platelet activation indices. Chronic cigarette smokers had higher circulating TPO levels than nonsmoking controls, as well as increased platelet-leukocyte binding, P-selectin expression, and CRP levels. Serum cotinine concentrations correlated with TPO concentrations, platelet-monocyte aggregates and P-selectin expression. In addition, TPO levels significantly correlated with ex vivo platelet-monocyte aggregation and P-selectin expression. In vitro, the plasma from cigarette smokers, but not from nonsmoking controls, primed platelet-monocyte binding, which was reduced when an inhibitor of TPO was used. We also found that acute smoking slightly increased TPO levels, but did not affect platelet-leukocyte binding, whereas smoking cessation induced a significant decrease in both circulating TPO and platelet-leukocyte aggregation. Elevated TPO contributes to enhance platelet activation and platelet-monocyte cross-talk in cigarette smokers. Copyright 2009 Elsevier Ireland Ltd. All rights reserved.

  8. Properties of Pliocene sedimentary geomagnetic reversal records from the Mediterranean

    NARCIS (Netherlands)

    Linssen, J.H.

    1991-01-01

    In the history of the Earth the dipolar geomagnetic field has frequently reversed polarity. Though this property was already known early this century (Brunhes, 1906), nowadays the characteristics and the origin of polarity transitions are still largely unknown. The geomagnetic field and its

  9. International Geomagnetic Reference Field: the 12th generation

    DEFF Research Database (Denmark)

    Thébault, Erwan; Finlay, Chris; Beggan, Ciarán D.

    2015-01-01

    The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch ...

  10. Geomagnetic observations on Tristan da Cunha, South Atlantic Ocean

    DEFF Research Database (Denmark)

    Matzka, J.; Olsen, Nils; Maule, C. F.

    2009-01-01

    Few geomagnetic ground observations exist of the Earth's strongest core field anomaly, the South Atlantic Anomaly (SAA). The geomagnetic repeat station on the island Tristan da Cunha, located half-way between South Africa and South America at 37 degrees 05' S, 12 degrees 18' W, is therefore of cr...

  11. Computation of geomagnetic elements for Nigeria for the year 2000 ...

    African Journals Online (AJOL)

    The Earth's magnetic field may be considered to be the sum of two parts, the main geomagnetic field which originates from the earth's fluid core, and the anomaly field that has its sources in the earth crust. The analysis of the geomagnetic field residual or anomaly, obtained from the difference between these two sources are ...

  12. Geomagnetic Field Variation during Winter Storm at Localized ...

    Indian Academy of Sciences (India)

    that transports plasma and magnetic flux which create the geomagnetic field variation. Key words. Dst—vertical component of interplanetary magnetic field and geomagnetic field components. 1. Introduction. The magnetic field is one of the important properties of the earth. The main magnetic field originates from ...

  13. Regional estimation of geomagnetically induced currents based on the local magnetic or electric field

    Directory of Open Access Journals (Sweden)

    Viljanen Ari

    2015-01-01

    Full Text Available Previous studies have demonstrated a close relationship between the time derivative of the horizontal geomagnetic field vector (dH/dt and geomagnetically induced currents (GIC at a nearby location in a power grid. Similarly, a high correlation exists between GIC and the local horizontal geoelectric field (E, typically modelled from a measured magnetic field. Considering GIC forecasting, it is not feasible to assume that detailed prediction of time series will be possible. Instead, other measures summarising the activity level over a given period are preferable. In this paper, we consider the 30-min maximum of dH/dt or E as a local activity indicator (|dH/dt|30 or |E|30. Concerning GIC, we use the sum of currents through the neutral leads at substations and apply its 30-min maximum as a regional activity measure (GIC30. We show that |dH/dt|30 at a single point yields a proxy for GIC activity in a larger region. A practical consequence is that if |dH/dt|30 can be predicted at some point then it is also possible to assess the expected GIC level in the surrounding area. As is also demonstrated, |E|30 and GIC30 depend linearly on |dH/dt|30, so there is no saturation with increasing geomagnetic activity contrary to often used activity indices.

  14. Chicago section activities to enhance public acceptance of nuclear power

    International Nuclear Information System (INIS)

    Snyder, T.L.; Keffer, J.W.

    1992-01-01

    The Chicago section of the American Nuclear Society (ANS) is an active organization with ∼450 members. The local section territory encompasses northern Illinois and includes in its territory all six of Commonwealth Edison Company's (CECo's) nuclear generating stations as well as Argonne National Laboratory (ANL). Included in the territory are several large engineering firms - ABB Impell, Bechtel, Fluor Daniel, and Sargent ampersand Lundy. The national headquarters of the ANS is also located within the local section boundaries. All these organizations are represented in the local section membership and provide access to abundant technical resources that can be used to enhance public acceptance of nuclear power. An important attribute of any local section that enables it to perform interesting programs and be active in the community is its financial resources. The Chicago section has a strong financial base because of its ability to raise funds by participating in and sponsoring ANS topical and other meetings. For instance, in 1991, they sponsored and were actively involved in the Emergency Preparedness Topical Meeting held in Chicago. In 1992, they were actively involved in sponsoring the organizational activities of the ANS/ENS International Meeting, which will celebrate the 50th year of nuclear fission. The financial and technical resources of the Chicago section continue to contribute to a successful program of public education and public acceptance activities regarding the nuclear industry

  15. Enhancement of DNA polymerase activity in potato tuber slices

    International Nuclear Information System (INIS)

    Watanabe, Akira; Imaseki, Hidemasa

    1977-01-01

    DNA polymerase was extracted from potato (Soleum tuberosum L.) tuber discs and the temporal correlation of its activity change to DNA synthesis in vivo was examined during aging of the discs. Most of the DNA polymerase was recovered as a bound form in the 18,000 x g precipitate. Reaction with the bound-form enzyme was dependent on the presence of four deoxynucleoside triphosphates, Mg 2+ , and a template. ''Activated'' DNA and heat-denatured DNA, but not native DNA, were utilized as templates. The polymerase activity was sensitive to SH reagents. Fresh discs, which do not synthesize DNA in vivo, contained a significant amount of DNA polymerase and its activity increased linearly with time until 48 hr after slicing and became four times that of fresh discs after 72 hr, whereas the activity of DNA synthesis in vivo increased with time and decreased after reaching a maximum at 30 hr. Cycloheximide inhibited the enhancement of polymerase activity. DNA polymerase from aged and fresh discs had identical requirements for deoxynucleotides and a template in their reactions, sensitivity to SH reagent, and affinity to thymidine triphosphate. (auth.)

  16. Resonance Raman Optical Activity and Surface Enhanced Resonance Raman Optical Activity analysis of Cytochrome C

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim; White, Peter C.

    2007-01-01

    High quality Resonance Raman (RR) and resonance Raman Optical Activity (ROA) spectra of cytochrome c were obtained in order to perform full assignment of spectral features of the resonance ROA spectrum. The resonance ROA spectrum of cytochrome c revealed a distinct spectral signature pattern due...... to resonance enhanced skeletal porphyrin vibrations, more pronounced than any contribution from the protein back-bone. Combining the intrinsic resonance enhancement of cytochrome c with surface plasmon enhancement by colloidal silver particles, the Surface Enhanced Resonance Raman Scattering (SERRS) and Chiral...... Enhanced Raman Spectroscopy (ChERS) spectra of the protein were successfully obtained at very low concentration (as low as 1 µM). The assignment of spectral features was based on the information obtained from the RR and resonance ROA spectra. Excellent agreement between RR and SERRS spectra is reported...

  17. Psychosocial Pain Management Moderation: The Limit, Activate, and Enhance Model.

    Science.gov (United States)

    Day, Melissa A; Ehde, Dawn M; Jensen, Mark P

    2015-10-01

    There is a growing emphasis in the pain literature on understanding the following second-order research questions: Why do psychosocial pain treatments work? For whom do various treatments work? This critical review summarizes research that addresses the latter question and proposes a moderation model to help guide future research. A theoretical moderation framework for matching individuals to specific psychosocial pain interventions has been lacking. However, several such frameworks have been proposed in the broad psychotherapy and implementation science literature. Drawing on these theories and adapting them specifically for psychosocial pain treatment, here we propose a Limit, Activate, and Enhance model of pain treatment moderation. This model is unique in that it includes algorithms not only for matching treatments on the basis of patient weaknesses but also for directing patients to interventions that build on their strengths. Critically, this model provides a basis for specific a priori hypothesis generation, and a selection of the possible hypotheses drawn from the model are proposed and discussed. Future research considerations are presented that could refine and expand the model based on theoretically driven empirical evidence. The Limit, Activate, and Enhance model presented here is a theoretically derived framework that provides an a priori basis for hypothesis generation regarding psychosocial pain treatment moderators. The model will advance moderation research via its unique focus on matching patients to specific treatments that (1) limit maladaptive responses, (2) activate adaptive responses, and (3) enhance treatment outcomes based on patient strengths and resources. Copyright © 2015 American Pain Society. Published by Elsevier Inc. All rights reserved.

  18. Hyperbaric Oxygen Environment Can Enhance Brain Activity and Multitasking Performance

    Directory of Open Access Journals (Sweden)

    Dor Vadas

    2017-09-01

    Full Text Available Background: The Brain uses 20% of the total oxygen supply consumed by the entire body. Even though, <10% of the brain is active at any given time, it utilizes almost all the oxygen delivered. In order to perform complex tasks or more than one task (multitasking, the oxygen supply is shifted from one brain region to another, via blood perfusion modulation. The aim of the present study was to evaluate whether a hyperbaric oxygen (HBO environment, with increased oxygen supply to the brain, will enhance the performance of complex and/or multiple activities.Methods: A prospective, double-blind randomized control, crossover trial including 22 healthy volunteers. Participants were asked to perform a cognitive task, a motor task and a simultaneous cognitive-motor task (multitasking. Participants were randomized to perform the tasks in two environments: (a normobaric air (1 ATA 21% oxygen (b HBO (2 ATA 100% oxygen. Two weeks later participants were crossed to the alternative environment. Blinding of the normobaric environment was achieved in the same chamber with masks on while hyperbaric sensation was simulated by increasing pressure in the first minute and gradually decreasing to normobaric environment prior to tasks performance.Results: Compared to the performance at normobaric conditions, both cognitive and motor single tasks scores were significantly enhanced by HBO environment (p < 0.001 for both. Multitasking performance was also significantly enhanced in HBO environment (p = 0.006 for the cognitive part and p = 0.02 for the motor part.Conclusions: The improvement in performance of both single and multi-tasking while in an HBO environment supports the hypothesis which according to, oxygen is indeed a rate limiting factor for brain activity. Hyperbaric oxygenation can serve as an environment for brain performance. Further studies are needed to evaluate the optimal oxygen levels for maximal brain performance.

  19. Gene activation regresses atherosclerosis, promotes health, and enhances longevity

    Directory of Open Access Journals (Sweden)

    Luoma Pauli V

    2010-07-01

    Full Text Available Abstract Background Lifestyle factors and pharmacological compounds activate genetic mechanisms that influence the development of atherosclerotic and other diseases. This article reviews studies on natural and pharmacological gene activation that promotes health and enhances longevity. Results Living habits including healthy diet and regular physical activity, and pharmacotherapy, upregulate genes encoding enzymes and apolipoprotein and ATP-binding cassette transporters, acting in metabolic processes that promote health and increase survival. Cytochrome P450-enzymes, physiological factors in maintaining cholesterol homeostasis, generate oxysterols for the elimination of surplus cholesterol. Hepatic CTP:phosphocholine cytidylyltransferase-α is an important regulator of plasma HDL-C level. Gene-activators produce plasma lipoprotein profile, high HDL-C, HDL2-C and HDL-C/cholesterol ratio, which is typical of low risk of atherosclerotic disease, and also of exceptional longevity together with reduced prevalence of cardiovascular, metabolic and other diseases. High HDL contributes to protection against inflammation, oxidation and thrombosis, and associates with good cognitive function in very old people. Avoiding unhealthy stress and managing it properly promotes health and increases life expectancy. Conclusions Healthy living habits and gene-activating xenobiotics upregulate mechanisms that produce lipoprotein pattern typical of very old people and enhance longevity. Lipoprotein metabolism and large HDL2 associate with the process of living a very long life. Major future goals for health promotion are the improving of commitment to both wise lifestyle choices and drug therapy, and further the developing of new and more effective and well tolerated drugs and treatments.

  20. Study about geomagnetic variations from data recorded at Surlari Geomagnetic Observatory

    Science.gov (United States)

    Asimopolos, Laurentiu; Asimopolos, Natalia-Silvia; Sandulescu, Agata Monica; Niculici, Eugen

    2013-04-01

    This paper presents statistical and spectral analysis of data from Surlari Geomagnetic Observatory that contributing to study of geomagnetic variations. Thus were highlighted, for long series of records over several solar cycles, periodicities of 22 years and 11 years. Following the same procedures for medium recording series (multi-annual) have highlighted annual, seasonal and monthly periodicities. For shorter data series, we highlighted diurnal, semidiurnal, 8 hours and even lower periodicities. For very short series with a high sample rate and for few magnetotellurics records, we highlight different types of pulsations (Pc2 - Pc5 and Pi 2). Geomagnetic signals are the convolution product of the atomic stationary signals mono-frequential of different amplitudes associated to phenomena with a very broad band of periodicities and nondeterministic signals associated with geomagnetic disturbances and non-periodic phenomena. Among analysis processes used for discrete series of geomagnetic data with different lengths and sampling rates, can conclude the following: Moving average works as a low pass filter in frequency or high pass in time. By eliminating high frequency components (depending on mobile window size used) can be studied preferential periodicities greater than a given value. Signal linearization (using least squares) provides information on linear trend of the entire series analyzed. Thus, for the very long data series (several decades) we extracted the secular variation slope for each geomagnetic component, separately. The numeric derivative of signal versus time proved to be a very reliable indicator for geomagnetic disturbed periods. Thus, the derivative value may be increased by several orders of magnitude during periods of agitation in comparisons to calm periods. The correlation factor shows significant increases when between two time series a causal relationship exists. Variation of the correlation factor, calculated for a mobile window containing k

  1. Optimal Transmission Line Switching under Geomagnetic Disturbances

    International Nuclear Information System (INIS)

    Lu, Mowen; Nagarajan, Harsha; Yamangil, Emre; Bent, Russell; Backhaus, Scott

    2017-01-01

    Recently, there have been increasing concerns about how geomagnetic disturbances (GMDs) impact electrical power systems. Geomagnetically-induced currents (GICs) can saturate transformers, induce hot spot heating and increase reactive power losses. These effects can potentially cause catastrophic damage to transformers and severely impact the ability of a power system to deliver power. To address this problem, we develop a model of GIC impacts to power systems that includes 1) GIC thermal capacity of transformers as a function of normal Alternating Current (AC) and 2) reactive power losses as a function of GIC. We also use this model to derive an optimization problem that protects power systems from GIC impacts through line switching, generator dispatch, and load shedding. We then employ state-of-the-art convex relaxations of AC power flow equations to lower bound the objective. We demonstrate the approach on a modified RTS96 system and UIUC 150-bus system and show that line switching is an effective means to mitigate GIC impacts. We also provide a sensitivity analysis of decisions with respect to GMD direction.

  2. Resolving issues concerning Eskdalemuir geomagnetic hourly values

    Directory of Open Access Journals (Sweden)

    S. Macmillan

    2011-02-01

    Full Text Available The hourly values of the geomagnetic field from 1911 to 1931 derived from measurements made at Eskdalemuir observatory in the UK, and available online from the World Data Centre for Geomagnetism at http://www.wdc.bgs.ac.uk/, have now been corrected. Previously they were 2-point averaged and transformed from the original north, east and vertical down values in the tables in the observatory yearbooks. This paper documents the course of events from discovering the post-processing done to the data to the final resolution of the problem. As it was through the development of a new index, the Inter-Hour Variability index, that this post-processing came to light, we provide a revised series of this index for Eskdalemuir and compare it with that from another European observatory. Conclusions of studies concerning long-term magnetic field variability and inferred solar variability, whilst not necessarily consistent with one another, are not obviously invalidated by the incorrect hourly values from Eskdalemuir. This series of events illustrates the challenges that lie ahead in removing any remaining errors and inconsistencies in the data holdings of different World Data Centres.

  3. Atmospheric helium and geomagnetic field reversals.

    Science.gov (United States)

    Sheldon, W. R.; Kern, J. W.

    1972-01-01

    The problem of the earth's helium budget is examined in the light of recent work on the interaction of the solar wind with nonmagnetic planets. It is proposed that the dominant mode of helium (He4) loss is ion pumping by the solar wind during geomagnetic field reversals, when the earth's magnetic field is very small. The interaction of the solar wind with the earth's upper atmosphere during such a period is found to involve the formation of a bow shock. The penetration altitude of the shock-heated solar plasma is calculated to be about 700 km, and ionization rates above this level are estimated for a cascade ionization (electron avalanche) process to average 10 to the 9th power ions/sq cm/sec. The calculated ionization rates and the capacity of the solar wind to remove ionized helium (He4) from the upper atmosphere during geomagnetic dipole reversals are sufficient to yield a secular equilibrium over geologic time scales. The upward transport of helium from the lower atmosphere under these conditions is found to be adequate to sustain the proposed loss rate.

  4. Geomagnetic control of polar mesosphere summer echoes

    Directory of Open Access Journals (Sweden)

    J. Bremer

    2000-02-01

    Full Text Available Using observations with the ALOMAR SOUSY radar near Andenes (69.3°N, 16.0°E from 1994 until 1997 polar mesosphere summer echoes (PMSE have been investigated in dependence on geomagnetic K indices derived at the Auroral Observatory Tromsø (69.66°N, 18.94°E. During night-time and morning hours a significant correlation between the signal-to-noise ratio (SNR of the radar results and the geomagnetic K indices could be detected with a maximum correlation near midnight. The correlation becomes markedly smaller in the afternoon and early evening hours with a minimum near 17 UT. This diurnal variation is in reasonable agreement with riometer absorption at Ivalo (68.55°N, 27.28°E and can be explained by the diurnal variation of ionization due to precipitating high energetic particles. Therefore, a part of the diurnal PMSE variation is caused by this particle precipitation. The variability of the solar EUV variation, however, has no significant influence on the PMSE during the observation period.Keywords: Ionosphere (auroral ionosphere - Magnetospheric physics (energetic particles, precipitating - Radio science (remote sensing

  5. Solar Wind Charge Exchange During Geomagnetic Storms

    Science.gov (United States)

    Robertson, Ina P.; Cravens, Thomas E.; Sibeck, David G.; Collier, Michael R.; Kuntz, K. D.

    2012-01-01

    On March 31st. 2001, a coronal mass ejection pushed the subsolar magnetopause to the vicinity of geosynchronous orbit at 6.6 RE. The NASA/GSFC Community Coordinated Modeling Center (CCMe) employed a global magnetohydrodynamic (MHD) model to simulate the solar wind-magnetosphere interaction during the peak of this geomagnetic storm. Robertson et aL then modeled the expected 50ft X-ray emission due to solar wind charge exchange with geocoronal neutrals in the dayside cusp and magnetosheath. The locations of the bow shock, magnetopause and cusps were clearly evident in their simulations. Another geomagnetic storm took place on July 14, 2000 (Bastille Day). We again modeled X-ray emission due to solar wind charge exchange, but this time as observed from a moving spacecraft. This paper discusses the impact of spacecraft location on observed X-ray emission and the degree to which the locations of the bow shock and magnetopause can be detected in images.

  6. Geomagnetically trapped carbon, nitrogen, and oxygen nuclei.

    Science.gov (United States)

    Mogro-Campero, A.

    1972-01-01

    Results of measurements carried out with the University of Chicago nuclear composition telescope on the Ogo 5 satellite, establishing the presence of 13- to 33-MeV/nucleon geomagnetically trapped C and O nuclei, with some evidence for N nuclei. These trapped nuclei were found at L less than or equal to 5 and near the geomagnetic equator. The data cover the period from Mar. 3, 1968, to Dec. 31, 1969. The distribution of CNO flux as a function of L is given. No change in the intensity of the average trapped CNO flux was detected by comparing data for 1968 and 1969. The results reported set a new value for the observed high energy limit of trapping as described by the critical adiabaticity parameter. The penetration of solar flare CNO up to L = 4 was observed twice in 1968, in disagreement with Stormer theory predictions. The effects of these results on some models for the origin of the trapped radiation are discussed.

  7. Large short-term deviations from dipolar field during the Levantine Iron Age Geomagnetic Anomaly ca. 1050-700 BCE

    Science.gov (United States)

    Shaar, R.; Tauxe, L.; Ebert, Y.

    2017-12-01

    Continuous decadal-resolution paleomagnetic data from archaeological and sedimentary sources in the Levant revealed the existence a local high-field anomaly, which spanned the first 350 years of the first millennium BCE. This so-called "the Levantine Iron Age geomagnetic Anomaly" (LIAA) was characterized by a high averaged geomagnetic field (virtual axial dipole moments, VADM > 140 Z Am2, nearly twice of today's field), short decadal-scale geomagnetic spikes (VADM of 160-185 Z Am2), fast directional and intensity variations, and substantial deviation (20°-25°) from dipole field direction. Similar high field values in the time frame of LIAA have been observed north, and northeast to the Levant: Eastern Anatolia, Turkmenistan, and Georgia. West of the Levant, in the Balkans, field values in the same time are moderate to low. The overall data suggest that the LIAA is a manifestation of a local positive geomagnetic field anomaly similar in magnitude and scale to the presently active negative South Atlantic Anomaly. In this presentation we review the overall archaeomagnetic and sedimentary evidences supporting the local anomaly hypothesis, and compare these observations with today's IGRF field. We analyze the global data during the first two millennia BCE, which suggest some unexpected large deviations from a simple dipolar geomagnetic structure.

  8. Psychopaths show enhanced amygdala activation during fear conditioning

    Directory of Open Access Journals (Sweden)

    Douglas eSchultz

    2016-03-01

    Full Text Available Psychopathy is a personality disorder characterized by emotional deficits and a failure to inhibit impulsive behavior and is often subdivided into primary and secondary psychopathic subtypes. The maladaptive behavior related to primary psychopathy is thought to reflect constitutional fearlessness, while the problematic behavior related to secondary psychopathy is motivated by other factors. The fearlessness observed in psychopathy has often been interpreted as reflecting a fundamental deficit in amygdala function, and previous studies have provided support for a low-fear model of psychopathy. However, many of these studies fail to use appropriate screening procedures, use liberal inclusion criteria, or have used unconventional approaches to assay amygdala function. We measured brain activity with BOLD imaging in primary and secondary psychopaths and non-psychopathic control subjects during Pavlovian fear conditioning. In contrast to the low-fear model, we observed normal fear expression in primary psychopaths. Psychopaths also displayed greater differential BOLD activity in the amygdala relative to matched controls. Inverse patterns of activity were observed in the anterior cingulate cortex (ACC for primary versus secondary psychopaths. Primary psychopaths exhibited a pattern of activity in the dorsal and ventral ACC consistent with enhanced fear expression, while secondary psychopaths exhibited a pattern of activity in these regions consistent with fear inhibition. These results contradict the low-fear model of psychopathy and suggest that the low fear observed for psychopaths in previous studies may be specific to secondary psychopaths.

  9. Enhancement of activated sludge disintegration and dewaterability by Fenton process

    Science.gov (United States)

    Heng, G. C.; Isa, M. H.

    2016-06-01

    Municipal and industrial wastewater treatment plants produce large amounts of sludge. This excess sludge is an inevitable drawback inherent to the activated sludge process. In this study, the waste activated sludge was obtained from the campus wastewater treatment plant at Universiti Teknologi PETRONAS (UTP), Malaysia. Fenton pretreatment was optimized by using the response surface methodology (RSM) to study the effects of three operating conditions including the dosage of H2O2 (g H2O2/kg TS), the molar ratio of H2O2/Fe2+ and reaction time. The optimum operating variables to achieve MLVSS removal 65%, CST reduction 28%, sCOD 11000 mg/L and EPS 500 mg/L were: 1000 g H2O2/kg TS, H2O2/Fe2+ molar ratio 70 and reaction time 45 min. Fenton process was proved to be able to enhance the sludge disintegration and dewaterability.

  10. MWCNT/CdS hybrid nanocomposite for enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Chaudhary, Deepti; Khare, Neeraj; Vankar, V. D.

    2016-01-01

    Multi-walled carbon nanotubes (MWCNT)/CdS hybrid nanocomposite were synthesized by one step hydrothermal method. MWCNTs were used as a substrate for the growth of CdS nanoparticles. MWCNT/CdS nanocomposite and pure CdS were characterized by XRD, TEM, UV-vis and photoluminescence spectroscopy. HRTEM study confirms the intimate contact of CdS with MWCNT. The photocatalytic activity of nanocomposite was studied for the degradation of methylene blue dye under UV irradiation. The enhanced photocatalytic activity of MWCNT/CdS nanocomposite as compared to pure CdS has been attributed to reduced recombination of photogenerated charge carriers due to interfacial electron transfer from CdS to MWCNT.

  11. Gamma irradiation enhances biological activities of mulberry leaf extract

    International Nuclear Information System (INIS)

    Cho, Byoung-Ok; Che, Denis Nchang; Yin, Hong-Hua; Jang, Seon-Il

    2017-01-01

    The purpose of this study was to investigate the influence of irradiation on the anti-oxidative, anti-inflammatory and whitening effects of mulberry leaf extract. This was done by comparing the phenolic contents; 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effects; 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) radical scavenging effects; in vitro tyrosinase inhibitory effects and the production of IL-6, TNF-α, PGE 2 , and NO in lipopolysaccharide-stimulated RAW264.7 macrophages and the production of IL-6 and TNF-α in phorbol 12-myristate 13-acetate plus calcium ionophore A23187-stimulated HMC-1 cells, respectively. The results showed that irradiated mulberry leaf extract possesses more anti-oxidant, anti-inflammatory, and tyrosinase inhibitory activities than their non-irradiated counterpart, probably due to increase in phenolic contents induced by gamma irradiation at dose of 10kGy. This research stresses on the importance of irradiation in functional foods. - Highlights: • Gamma-irradiated mulberry leaf extract enhanced in vitro antioxidant activities. • Gamma-irradiated mulberry leaf extract enhanced in vitro tyrosinase inhibitory effects. • Gamma-irradiated mulberry leaf extract treatment reduced the production of IL-6, TNF-α, PGE 2 , and NO.

  12. Silver enhances antibiotic activity against gram-negative bacteria.

    Science.gov (United States)

    Morones-Ramirez, J Ruben; Winkler, Jonathan A; Spina, Catherine S; Collins, James J

    2013-06-19

    A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. We show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism, and iron homeostasis. These changes lead to increased production of reactive oxygen species and increased membrane permeability of Gram-negative bacteria that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive-specific antibiotic vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model that silver can enhance antibacterial action against bacteria that produce biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections.

  13. Hyperbaric Oxygen Environment Can Enhance Brain Activity and Multitasking Performance.

    Science.gov (United States)

    Vadas, Dor; Kalichman, Leonid; Hadanny, Amir; Efrati, Shai

    2017-01-01

    Background: The Brain uses 20% of the total oxygen supply consumed by the entire body. Even though, multitasking), the oxygen supply is shifted from one brain region to another, via blood perfusion modulation. The aim of the present study was to evaluate whether a hyperbaric oxygen (HBO) environment, with increased oxygen supply to the brain, will enhance the performance of complex and/or multiple activities. Methods: A prospective, double-blind randomized control, crossover trial including 22 healthy volunteers. Participants were asked to perform a cognitive task, a motor task and a simultaneous cognitive-motor task (multitasking). Participants were randomized to perform the tasks in two environments: (a) normobaric air (1 ATA 21% oxygen) (b) HBO (2 ATA 100% oxygen). Two weeks later participants were crossed to the alternative environment. Blinding of the normobaric environment was achieved in the same chamber with masks on while hyperbaric sensation was simulated by increasing pressure in the first minute and gradually decreasing to normobaric environment prior to tasks performance. Results: Compared to the performance at normobaric conditions, both cognitive and motor single tasks scores were significantly enhanced by HBO environment ( p Multitasking performance was also significantly enhanced in HBO environment ( p = 0.006 for the cognitive part and p = 0.02 for the motor part). Conclusions: The improvement in performance of both single and multi-tasking while in an HBO environment supports the hypothesis which according to, oxygen is indeed a rate limiting factor for brain activity. Hyperbaric oxygenation can serve as an environment for brain performance. Further studies are needed to evaluate the optimal oxygen levels for maximal brain performance.

  14. Long periods (1 -10 mHz) geomagnetic pulsations variation with solar cycle in South Atlantic Magnetic Anomaly

    Science.gov (United States)

    Rigon Silva, Willian; Schuch, Nelson Jorge; Guimarães Dutra, Severino Luiz; Babulal Trivedi, Nalin; Claudir da Silva, Andirlei; Souza Savian, Fernando; Ronan Coelho Stekel, Tardelli; de Siqueira, Josemar; Espindola Antunes, Cassio

    The occurrence and intensity of the geomagnetic pulsations Pc-5 (2-7 mHz) and its relationship with the solar cycle in the South Atlantic Magnetic Anomaly -SAMA is presented. The study of geomagnetic pulsations is important to help the understanding of the physical processes that occurs in the magnetosphere region and help to predict geomagnetic storms. The fluxgate mag-netometers H, D and Z, three axis geomagnetic field data from the Southern Space Observatory -SSO/CRS/INPE -MCT, São Martinho da Serra (29.42° S, 53.87° W, 480m a.s.l.), RS, Brasil, a were analyzed and correlated with the solar wind parameters (speed, density and temperature) from the ACE and SOHO satellites. A digital filtering to enhance the 2-7 mHz geomagnetic pulsations was used. Five quiet days and five perturbed days in the solar minimum and in the solar maximum were selected for this analysis. The days were chosen based on the IAGA definition and on the Bartels Musical Diagrams (Kp index) for 2001 (solar maximum) and 2008 (solar minimum). The biggest Pc-5 amplitude averages differences between the H-component is 78,35 nT for the perturbed days and 1,60nT for the quiet days during the solar maximum. For perturbed days the average amplitude during the solar minimum is 8,32 nT, confirming a direct solar cycle influence in the geomagnetic pulsations intensity for long periods.

  15. The 2015 Summer Solstice Storm: One of the Major Geomagnetic Storms of Solar Cycle 24 Observed at Ground Level

    Science.gov (United States)

    Augusto, C. R. A.; Navia, C. E.; de Oliveira, M. N.; Nepomuceno, A. A.; Raulin, J. P.; Tueros, E.; de Mendonça, R. R. S.; Fauth, A. C.; Vieira de Souza, H.; Kopenkin, V.; Sinzi, T.

    2018-05-01

    We report on the 22 - 23 June 2015 geomagnetic storm that occurred at the summer solstice. There have been fewer intense geomagnetic storms during the current solar cycle, Solar Cycle 24, than in the previous cycle. This situation changed after mid-June 2015, when one of the largest solar active regions (AR 12371) of Solar Cycle 24 that was located close to the central meridian, produced several coronal mass ejections (CMEs) associated with M-class flares. The impact of these CMEs on the Earth's magnetosphere resulted in a moderate to severe G4-class geomagnetic storm on 22 - 23 June 2015 and a G2 (moderate) geomagnetic storm on 24 June. The G4 solstice storm was the second largest (so far) geomagnetic storm of Cycle 24. We highlight the ground-level observations made with the New-Tupi, Muonca, and the CARPET El Leoncito cosmic-ray detectors that are located within the South Atlantic Anomaly (SAA) region. These observations are studied in correlation with data obtained by space-borne detectors (ACE, GOES, SDO, and SOHO) and other ground-based experiments. The CME designations are taken from the Computer Aided CME Tracking (CACTus) automated catalog. As expected, Forbush decreases (FD) associated with the passing CMEs were recorded by these detectors. We note a peculiar feature linked to a severe geomagnetic storm event. The 21 June 2015 CME 0091 (CACTus CME catalog number) was likely associated with the 22 June summer solstice FD event. The angular width of CME 0091 was very narrow and measured {˜} 56° degrees seen from Earth. In most cases, only CME halos and partial halos lead to severe geomagnetic storms. We perform a cross-check analysis of the FD events detected during the rise phase of Solar Cycle 24, the geomagnetic parameters, and the CACTus CME catalog. Our study suggests that narrow angular-width CMEs that erupt in a westward direction from the Sun-Earth line can lead to moderate and severe geomagnetic storms. We also report on the strong solar proton

  16. Evolution of the ring current during two geomagnetic storms

    International Nuclear Information System (INIS)

    Lui, A.T.Y.; McEntire, R.W.; Krimigis, S.M.

    1987-01-01

    The progressive developments in the radial profiles of the particle pressure, plasma beta, and electric currents of the storm time ring current are investigated with data from the medium energy particle analyzer on the AMPTE Charged Particle Explorer spacecraft. Measurements of ions from 25 keV to 1 MeV, which carry 70--85% of the energy density of the entire ring current population, are used in this work. Two geomagnetic storms in September of 1984 are selected and four traversals of the equatorial ring current region during the course of each storm are studied. It is shown that enhancements in the particle pressure occur initially in the outer region and reach the inner region in the late phase of the storm. Structures suggestive of multiple particle injections are seen in the pressure profile. The leading and trailing edges of the particle injection structures are associated, respectively, with the depressions and enhancements of the westward current densities of the ring current. Plasma beta occasionally increases to values of the order of 1 in some regions of the ring current from prestorm values of the order of 0.1 or less. It is also found that the location of the maximum ring current particle pressure can be several earth radii from where the most intense westward ring current flows. This is a consequence of the dominance of pressure gradient current over the current associated with the magnetic field line curvature and particle anisotropy. copyright American Geophysical Union 1987

  17. Sports activities enhance the prevalence of rhinitis symptoms in schoolchildren.

    Science.gov (United States)

    Kusunoki, Takashi; Takeuchi, Jiro; Morimoto, Takeshi; Sakuma, Mio; Mukaida, Kumiko; Yasumi, Takahiro; Nishikomori, Ryuta; Heike, Toshio

    2016-03-01

    To evaluate the association between sports activities and allergic symptoms, especially rhinitis, among schoolchildren. This longitudinal survey of schoolchildren collected data from questionnaires regarding allergic symptoms based on the International Study of Asthma and Allergies in Childhood (ISAAC) program and sports participation that were distributed to the parents of children at all 12 public primary schools in Ohmi-Hachiman City, Shiga Prefecture, Japan. Data were collected annually from 2011 until 2014, when the children reached 10 years of age. Blood samples were obtained in 2014, and the levels of immunoglobulin (Ig)E specific to four inhalant allergens were measured. Data from 558 children were analyzed. At 10 years of age, prevalence of asthma and eczema did not differ significantly, while rhinitis was significantly higher (p = 0.009) among children who participated in sports. Prevalence of rhinitis increased as the frequency or duration of sports participation increased (p sports (p = 0.03). Among those who participated in continuous sports activities, the prevalence of rhinitis was significantly higher with prolonged eczema (p = 0.006). Sports activities did not increase sensitization to inhalant allergens. Sports activities enhance the prevalence of rhinitis in schoolchildren. Prolonged eczema, together with sports participation, further promotes the symptoms. The mechanisms of these novel findings warrant further investigation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. PERSPECTIVE: Electrical activity enhances neuronal survival and regeneration

    Science.gov (United States)

    Corredor, Raul G.; Goldberg, Jeffrey L.

    2009-10-01

    The failure of regeneration in the central nervous system (CNS) remains an enormous scientific and clinical challenge. After injury or in degenerative diseases, neurons in the adult mammalian CNS fail to regrow their axons and reconnect with their normal targets, and furthermore the neurons frequently die and are not normally replaced. While significant progress has been made in understanding the molecular basis for this lack of regenerative ability, a second approach has gained momentum: replacing lost neurons or lost connections with artificial electrical circuits that interface with the nervous system. In the visual system, gene therapy-based 'optogenetics' prostheses represent a competing technology. Now, the two approaches are converging, as recent data suggest that electrical activity itself, via the molecular signaling pathways such activity stimulates, is sufficient to induce neuronal survival and regeneration, particularly in retinal ganglion cells. Here, we review these data, discuss the effects of electrical activity on neurons' molecular signaling pathways and propose specific mechanisms by which exogenous electrical activity may be acting to enhance survival and regeneration.

  19. Enhanced multimaterial 4D printing with active hinges

    Science.gov (United States)

    Akbari, Saeed; Hosein Sakhaei, Amir; Kowsari, Kavin; Yang, Bill; Serjouei, Ahmad; Yuanfang, Zhang; Ge, Qi

    2018-06-01

    Despite great progress in four-dimensional (4D) printing, i.e. three-dimensional (3D) printing of active (stimuli-responsive) materials, the relatively low actuation force of the 4D printed structures often impedes their engineering applications. In this study, we use multimaterial inkjet 3D printing technology to fabricate shape memory structures, including a morphing wing flap and a deployable structure, which consist of active and flexible hinges joining rigid (non-active) parts. The active hinges, printed from a shape memory polymer (SMP), lock the structure into a second temporary shape during a thermomechanical programming process, while the flexible hinges, printed from an elastomer, effectively increase the actuation force and the load-bearing capacity of the printed structure as reflected in the recovery ratio. A broad range of mechanical properties such as modulus and failure strain can be achieved for both active and flexible hinges by varying the composition of the two base materials, i.e. the SMP and the elastomer, to accommodate large deformation induced during programming step, and enhance the recovery in the actuating step. To find the important design parameters, including local deformation, shape fixity and recovery ratio, we conduct high fidelity finite element simulations, which are able to accurately predict the nonlinear deformation of the printed structures. In addition, a coupled thermal-electrical finite element analysis was performed to model the heat transfer within the active hinges during the localized Joule heating process. The model predictions showed good agreement with the measured temperature data and were used to find the major parameters affecting temperature distribution including the applied voltage and the convection rate.

  20. Aged refuse enhances anaerobic digestion of waste activated sludge.

    Science.gov (United States)

    Zhao, Jianwei; Gui, Lin; Wang, Qilin; Liu, Yiwen; Wang, Dongbo; Ni, Bing-Jie; Li, Xiaoming; Xu, Rui; Zeng, Guangming; Yang, Qi

    2017-10-15

    In this work, a low-cost alternative approach (i.e., adding aged refuse (AR) into waste activated sludge) to significantly enhance anaerobic digestion of sludge was reported. Experimental results showed that with the addition dosage of AR increasing from 0 to 400 mg/g dry sludge soluble chemical oxygen demand (COD) increased from 1150 to 5240 mg/L at the digestion time of 5 d, while the maximal production of volatile fatty acids (VFA) increased from 82.6 to 183.9 mg COD/g volatile suspended solids. Although further increase of AR addition decreased the concentrations of both soluble COD and VFA, their contents in these systems with AR addition at any concentration investigated were still higher than those in the blank, which resulted in higher methane yields in these systems. Mechanism studies revealed that pertinent addition of AR promoted solubilization, hydrolysis, and acidogenesis processes and did not affect methanogenesis significantly. It was found that varieties of enzymes and anaerobes in AR were primary reason for the enhancement of anaerobic digestion. Humic substances in AR benefited hydrolysis and acidogenesis but inhibited methanogenesis. The effect of heavy metals in AR on sludge anaerobic digestion was dosage dependent. Sludge anaerobic digestion was enhanced by appropriate amounts of heavy metals but inhibited by excessive amounts of heavy metals. The relative abundances of microorganisms responsible for sludge hydrolysis and acidogenesis were also observed to be improved in the system with AR addition, which was consistent with the performance of anaerobic digestion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Response of the middle atmosphere to the geomagnetic storm of November 2004

    Science.gov (United States)

    Hocke, Klemens

    2017-02-01

    Ozone and temperature profiles of the satellite microwave limb sounder Aura/MLS are used for the derivation of the middle atmospheric response to the geomagnetic superstorm of 9 November 2004. We find a destruction of the tertiary ozone layer at 0.022 hPa (77 km) in the northern winter hemisphere lasting for about one week. This effect is surely due to the solar proton event (SPE) of November 2004. At the same time, the zonal mean temperature is enhanced by 5-10 K in the northern polar mesosphere. On the other hand, the zonal mean temperature is decreased by 5-10 K in the northern polar stratosphere. We do not think that the strong temperature perturbations are directly related to the SPE. It seems that the polar vortex was moved by the geomagnetic storm, and this vortex movement caused the strong temperature variations in the zonal mean. However, internal variability of temperature in the polar middle atmosphere in winter without any significant link to the geomagnetic storm cannot be excluded.

  2. A theoretical study of thermospheric composition perturbations during an impulsive geomagnetic storm

    International Nuclear Information System (INIS)

    Burns, A.G.; Killeen, T.L.; Roble, R.G.

    1991-01-01

    The compositional response of the neutral thermosphere to an impulsive geomagnetic storm has been investigated using a numerical simulation made with the National Center for Atmospheric Research thermospheric general circulation model (NCAR-TGCM). Calculated time-dependent changes in neutral thermospheric composition have been studied, together with detailed neutral parcel trajectories and other diagnostic information from the model, to gain a greater understanding of the physical mechanisms responsible for composition variability during geomagnetic storms and, in particular, to investigate the causes of the positive and negative ionospheric storm effects. The following principal results were obtained from this study. (1) Calculated perturbations in thermospheric composition following the onset of an impulsive geomagnetic storm were found to be in good qualitative agreement with the previous experimental statistical study of storm time thermospheric morphology by Proelss. (2) During the initial (onset) phase of the simulated storm, upward vertical winds occurred in the auroral zone and downward winds occurred in the central magnetic polar cap. (3) The largest perturbations in mass mixing ratio of nitrogen at F region altitudes were found to be associated with parcels of neutral gas that travelled through the cusp region and with parcels that were trapped within the auroral zone for a long time. (4) Storm time enhancements in Ψ N 2 were found to occur in the midnight and early morning sectors both within and equatorward of the auroral zone, and these were determined to be associated with the advective effects of the large antisunward polar cap neutral winds

  3. Statistical Study of False Alarms of Geomagnetic Storms

    DEFF Research Database (Denmark)

    Leer, Kristoffer; Vennerstrøm, Susanne; Veronig, A.

    . A subset of these halo CMEs did not cause a geomagnetic storm the following four days and have therefore been considered as false alarms. The properties of these events are investigated and discussed here. Their statistics are compared to the geo-effective CMEs. The ability to identify potential false......Coronal Mass Ejections (CMEs) are known to cause geomagnetic storms on Earth. However, not all CMEs will trigger geomagnetic storms, even if they are heading towards the Earth. In this study, front side halo CMEs with speed larger than 500 km/s have been identified from the SOHO LASCO catalogue...

  4. Soluble ICAM-1 activates lung macrophages and enhances lung injury

    DEFF Research Database (Denmark)

    Schmal, H; Czermak, B J; Lentsch, A B

    1998-01-01

    production of TNF-alpha and the CXC chemokine, macrophage inflammatory protein-2 (MIP-2). Alveolar macrophages exhibited cytokine responses to both sICAM-1 and immobilized sICAM-1, while rat PBMCs failed to demonstrate similar responses. Exposure of alveolar macrophages to sICAM-1 resulted in NFkappa......B activation (which was blocked by the presence of the aldehyde peptide inhibitor of 28S proteosome and by genistein, a tyrosine kinase inhibitor). As expected, cross-linking of CD18 on macrophages with Ab resulted in generation of TNF-alpha and MIP-2. This response was also inhibited in the presence...... of TNF-alpha and MIP-2 and increased neutrophil recruitment. Therefore, through engagement of beta2 integrins, sICAM-1 enhances alveolar macrophage production of MIP-2 and TNF-alpha, the result of which is intensified lung injury after intrapulmonary disposition of immune complexes....

  5. Slow-light-enhanced gain in active photonic crystal waveguides

    DEFF Research Database (Denmark)

    Ek, Sara; Hansen, Per Lunnemann; Chen, Yaohui

    2014-01-01

    Passive photonic crystals have been shown to exhibit a multitude of interesting phenomena, including slow-light propagation in line-defect waveguides. It was suggested that by incorporating an active material in the waveguide, slow light could be used to enhance the effective gain of the material......, which would have interesting application prospects, for example enabling ultra-compact optical amplifiers for integration in photonic chips. Here we experi- mentally investigate the gain of a photonic crystal membrane structure with embedded quantum wells. We find that by solely changing the photonic...... crystal structural parameters, the maximum value of the gain coefficient can be increased compared with a ridge waveguide structure and at the same time the spectral position of the peak gain be controlled. The experimental results are in qualitative agreement with theory and show that gain values similar...

  6. Autophagic machinery activated by dengue virus enhances virus replication

    International Nuclear Information System (INIS)

    Lee, Y.-R.; Lei, H.-Y.; Liu, M.-T.; Wang, J.-R.; Chen, S.-H.; Jiang-Shieh, Y.-F.; Lin, Y.-S.; Yeh, T.-M.; Liu, C.-C.; Liu, H.-S.

    2008-01-01

    Autophagy is a cellular response against stresses which include the infection of viruses and bacteria. We unravel that Dengue virus-2 (DV2) can trigger autophagic process in various infected cell lines demonstrated by GFP-LC3 dot formation and increased LC3-II formation. Autophagosome formation was also observed under the transmission electron microscope. DV2-induced autophagy further enhances the titers of extracellular and intracellular viruses indicating that autophagy can promote viral replication in the infected cells. Moreover, our data show that ATG5 protein is required to execute DV2-induced autophagy. All together, we are the first to demonstrate that DV can activate autophagic machinery that is favorable for viral replication

  7. GEOMAGNETIC CONJUGACY OF MODERN TECTONIC STRUCTURES

    Directory of Open Access Journals (Sweden)

    G. Ya. Khachikyan

    2013-01-01

    Full Text Available An earthquake is an element of the global electric circuit (GEC –  this new idea suggested in the space age is tested in our study. In the frame of the GEC concept, one may expect that tectonic structures of the northern and southern hemispheres may be magnetically conjugated. It is found that the midocean ridges of the southern hemisphere, located along the boundary of the Antarctic lithosphere plate, are magnetically conjugated with the areas of the junction of continental orogens and platforms in the northern hemisphere. The closest geomagnetic conjugacy exists between the southern boundary of Nazca lithospheric plate and the northern boundaries of Cocos and Caribbean lithospheric plates.

  8. Cloud-based calculators for fast and reliable access to NOAA's geomagnetic field models

    Science.gov (United States)

    Woods, A.; Nair, M. C.; Boneh, N.; Chulliat, A.

    2017-12-01

    While the Global Positioning System (GPS) provides accurate point locations, it does not provide pointing directions. Therefore, the absolute directional information provided by the Earth's magnetic field is of primary importance for navigation and for the pointing of technical devices such as aircrafts, satellites and lately, mobile phones. The major magnetic sources that affect compass-based navigation are the Earth's core, its magnetized crust and the electric currents in the ionosphere and magnetosphere. NOAA/CIRES Geomagnetism (ngdc.noaa.gov/geomag/) group develops and distributes models that describe all these important sources to aid navigation. Our geomagnetic models are used in variety of platforms including airplanes, ships, submarines and smartphones. While the magnetic field from Earth's core can be described in relatively fewer parameters and is suitable for offline computation, the magnetic sources from Earth's crust, ionosphere and magnetosphere require either significant computational resources or real-time capabilities and are not suitable for offline calculation. This is especially important for small navigational devices or embedded systems, where computational resources are limited. Recognizing the need for a fast and reliable access to our geomagnetic field models, we developed cloud-based application program interfaces (APIs) for NOAA's ionospheric and magnetospheric magnetic field models. In this paper we will describe the need for reliable magnetic calculators, the challenges faced in running geomagnetic field models in the cloud in real-time and the feedback from our user community. We discuss lessons learned harvesting and validating the data which powers our cloud services, as well as our strategies for maintaining near real-time service, including load-balancing, real-time monitoring, and instance cloning. We will also briefly talk about the progress we achieved on NOAA's Big Earth Data Initiative (BEDI) funded project to develop API

  9. Geomagnetism and paleomagnetism 1979-1983

    Science.gov (United States)

    Fuller, M.

    My function, in writing these notes, is to bring you up to date in Geomagnetism and Paleomagnetism, in as painless a manner as possible—without tears, as the French language texts for tourists used to promise. In writing this account of progress in the past quadrennium, I must first acknowledge that it is a personal and subjective viewpoint;; another reporter would surely emphasize other developments. Yet, there is some virture in writing of things, about which one knows something, so I leave to future reporters the task of redresssing the balance in matters covered.At the outset, one very sad event must be recorded. On April 3, 1981, Sir Edward Bullard died. His published work alone marks him as one of the leaders of geomagnetism in our times. Yet his contribution was much greater; many an American geophysicist, as well as a whole generation of British colleagues, have felt the benefit of his perceptive advice on their research. To those who saw him in the last few months of his life, his courage in the face of his illness was a remarkable example of fortitude. It is by now well known that the definitive paper, which he wrote with Malin, on secular variation at London, was only completed immediately before his death. The transmittal letter had been typed, but death prevented him from signing it. Bullard returned in this final paper to a topic to which he had contributed much. In it, he notes the role of Halley, who first described the phenomenon of westward drift, to which Bullard gave a new numerical precision, two and a half centuries later. I seem to remember Bullard saying in a lecture years ago that, while the Newtons of this world seem other than mortal, Halley was a scientist whose life and acheivements could encourage one's own efforts. Bullard, like Halley, inspires and encourages us.

  10. Ultrasound enhanced activation of peroxydisulfate by activated carbon fiber for decolorization of azo dye.

    Science.gov (United States)

    Huang, Tianyin; Zhang, Ke; Qian, Yajie; Fang, Cong; Chen, Jiabin

    2018-02-20

    Activated carbon fiber (ACF) has become an emerging activator for peroxydisulfate (PDS) to generate sulfate radical (SO 4 •- ). However, the relative low activation efficiency and poor contaminant mineralization limited its widespread application. Herein, ultrasound (US) was introduced to the ACF activated PDS system, and the synergistic effect of US and ACF in PDS activation and the enhancement of contaminant mineralization were investigated. The synergistic effect of US and ACF was observed in the PDS activation to decolorize orange G (OG). The decolorization efficiency increased with increasing ACF loading and US power, and PDS/OG ratio from 1 to 40. The activation energy was determined to be 24.065 kJ/mol. The radical-induced decolorization of OG took place on the surface of ACF, and both SO 4 •- and hydroxyl radical ( • OH) contributed to OG decolorization. The azo bond and naphthalene ring on OG were destructed to other aromatic intermediates and finally mineralized to CO 2 and H 2 O. The introduction of US in the ACF/PDS system significantly enhanced the mineralization of OG. The combination of US and PDS was highly efficient to activate PDS to decolorize azo dyes. Moreover, the introduction of US remarkably improved the contaminant mineralization.

  11. Enhancing anaerobic digestion of poultry blood using activated carbon

    Directory of Open Access Journals (Sweden)

    Maria José Cuetos

    2017-05-01

    Full Text Available The potential of using anaerobic digestion for the treatment of poultry blood has been evaluated in batch assays at the laboratory scale and in a mesophilic semi-continuous reactor. The biodegradability test performed on residual poultry blood was carried out in spite of high inhibitory levels of acid intermediaries. The use of activated carbon as a way to prevent inhibitory conditions demonstrated the feasibility of attaining anaerobic digestion under extreme ammonium and acid conditions. Batch assays with higher carbon content presented higher methane production rates, although the difference in the final cumulative biogas production was not as sharp. The digestion of residual blood was also studied under semi-continuous operation using granular and powdered activated carbon. The average specific methane production was 216 ± 12 mL CH4/g VS. This result was obtained in spite of a strong volatile fatty acid (VFA accumulation, reaching values around 6 g/L, along with high ammonium concentrations (in the range of 6–8 g/L. The use of powdered activated carbon resulted in a better assimilation of C3-C5 acid forms, indicating that an enhancement in syntrophic metabolism may have taken place. Thermal analysis and scanning electron microscopy (SEM were applied as analytical tools for measuring the presence of organic material in the final digestate and evidencing modifications on the carbon surface. The addition of activated carbon for the digestion of residual blood highly improved the digestion process. The adsorption capacity of ammonium, the protection this carrier may offer by limiting mass transfer of toxic compounds, and its capacity to act as a conductive material may explain the successful digestion of residual blood as the sole substrate.

  12. Bottom-up control of geomagnetic secular variation by the Earth's inner core

    DEFF Research Database (Denmark)

    Aubert, Julien; Finlay, Chris; Fournier, Alexandre

    2013-01-01

    of geomagnetic secular variation. Here we show that it can be reproduced provided that two mechanisms relying on the inner core are jointly considered. First, gravitational coupling5 aligns the inner core with the mantle, forcing the flow of liquid metal in the outer core into a giant, westward drifting, sheet...... release in the outer core which in turn distorts the gyre, forcing it to become eccentric, in agreement with recent core flow inversions6, 10, 11. This bottom-up heterogeneous driving of core convection dominates top-down driving from mantle thermal heterogeneities, and localizes magnetic variations......Temporal changes in the Earth’s magnetic field, known as geomagnetic secular variation, occur most prominently at low latitudes in the Atlantic hemisphere1, 2 (that is, from −90 degrees east to 90 degrees east), whereas in the Pacific hemisphere there is comparatively little activity...

  13. Ionospheric Data Assimilation and Targeted Observation Strategies: Proof of Concept Analysis in a Geomagnetic Storm Event

    Science.gov (United States)

    Kostelich, Eric; Durazo, Juan; Mahalov, Alex

    2017-11-01

    The dynamics of the ionosphere involve complex interactions between the atmosphere, solar wind, cosmic radiation, and Earth's magnetic field. Geomagnetic storms arising from solar activity can perturb these dynamics sufficiently to disrupt radio and satellite communications. Efforts to predict ``space weather,'' including ionospheric dynamics, require the development of a data assimilation system that combines observing systems with appropriate forecast models. This talk will outline a proof-of-concept targeted observation strategy, consisting of the Local Ensemble Transform Kalman Filter, coupled with the Thermosphere Ionosphere Electrodynamics Global Circulation Model, to select optimal locations where additional observations can be made to improve short-term ionospheric forecasts. Initial results using data and forecasts from the geomagnetic storm of 26-27 September 2011 will be described. Work supported by the Air Force Office of Scientific Research (Grant Number FA9550-15-1-0096) and by the National Science Foundation (Grant Number DMS-0940314).

  14. Enhancement of hypoxia-activated prodrug TH-302 anti-tumor activity by Chk1 inhibition.

    Science.gov (United States)

    Meng, Fanying; Bhupathi, Deepthi; Sun, Jessica D; Liu, Qian; Ahluwalia, Dharmendra; Wang, Yan; Matteucci, Mark D; Hart, Charles P

    2015-05-21

    The hypoxia-activated prodrug TH-302 is reduced at its nitroimidazole group and selectively under hypoxic conditions releases the DNA cross-linker bromo-isophosphoramide mustard (Br-IPM). Here, we have explored the effect of Chk1 inhibition on TH-302-mediated pharmacological activities. We employed in vitro cell viability, DNA damage, cellular signaling assays and the in vivo HT29 human tumor xenograft model to study the effect of Chk1inhibition on TH-302 antitumor activities. TH-302 cytotoxicity is greatly enhanced by Chk1 inhibition in p53-deficient but not in p53-proficient human cancer cell lines. Chk1 inhibitors reduced TH-302-induced cell cycle arrest via blocking TH-302-induced decrease of phosphorylation of histone H3 and increasing Cdc2-Y15 phosphorylation. Employing the single-cell gel electrophoresis (comet) assay, we observed a potentiation of the TH-302 dependent tail moment. TH-302 induced γH2AX and apoptosis were also increased upon the addition of Chk1 inhibitor. Potentiation of TH-302 cytotoxicity by Chk1 inhibitor was only observed in cell lines proficient in, but not deficient in homology-directed DNA repair. We also show that combination treatment led to lowering of Rad51 expression levels as compared to either agent alone. In vivo data demonstrate that Chk1 inhibitor enhances TH-302 anti-tumor activity in p53 mutant HT-29 human tumor xenografts, supporting the hypothesis that these in vitro results can translate to enhanced in vivo efficacy of the combination. TH-302-mediated in vitro and in vivo anti-tumor activities were greatly enhanced by the addition of Chk1 inhibitors. The preclinical data presented in this study support a new approach for the treatment of p53-deficient hypoxic cancers by combining Chk1 inhibitors with the hypoxia-activated prodrug TH-302.

  15. Energization of the Ring Current through Convection of Substorm Enhancements of the Plasma Sheet Source.

    Science.gov (United States)

    Menz, A.; Kistler, L. M.; Mouikis, C.; Spence, H. E.; Henderson, M. G.; Matsui, H.

    2017-12-01

    It has been shown that electric field strength and night-side plasma sheet density are the two best predictors of the adiabatic energy gain of the ring current during geomagnetic storms (Liemohn and Khazanov, 2005). While H+ dominates the ring current during quiet times, O+ can contribute substantially during geomagnetic storms. Substorm activity provides a mechanism to enhance the energy density of O+ in the plasma sheet during geomagnetic storms, which is then convected adiabatically into the inner-magnetosphere. Using the Van Allen Probes data in the the plasma sheet source region (defined as L>5.5 during storms) and the inner magnetosphere, along with LANL-GEO data to identify substorm injection times, we show that adiabatic convection of O+ enhancements in the source region can explain the observed enhancements in the inner magnetosphere. We use the UNH-IMEF electric field model to calculate drift times from the source region to the inner magnetosphere to test whether enhancements in the inner-magnetosphere can be explained by dipolarization driven enhancements in the plasma sheet source hours before.

  16. Human PrimPol activity is enhanced by RPA.

    Science.gov (United States)

    Martínez-Jiménez, María I; Lahera, Antonio; Blanco, Luis

    2017-04-10

    Human PrimPol is a primase belonging to the AEP superfamily with the unique ability to synthesize DNA primers de novo, and a non-processive DNA polymerase able to bypass certain DNA lesions. PrimPol facilitates both mitochondrial and nuclear replication fork progression either acting as a conventional TLS polymerase, or repriming downstream of blocking lesions. In vivo assays have shown that PrimPol is rapidly recruited to sites of DNA damage by interaction with the human replication protein A (RPA). In agreement with previous findings, we show here that the higher affinity of RPA for ssDNA inhibits PrimPol activities in short ssDNA templates. In contrast, once the amount of ssDNA increases up to a length in which both proteins can simultaneously bind ssDNA, as expected during replicative stress conditions, PrimPol and RPA functionally interact, and their binding capacities are mutually enhanced. When using M13 ssDNA as template, RPA stimulated both the primase and polymerase activities of PrimPol, either alone or in synergy with Polε. These new findings supports the existence of a functional PrimPol/RPA association that allows repriming at the exposed ssDNA regions formed in the leading strand upon replicase stalling.

  17. Active screen plasma nitriding enhances cell attachment to polymer surfaces

    International Nuclear Information System (INIS)

    Kaklamani, Georgia; Bowen, James; Mehrban, Nazia; Dong, Hanshan; Grover, Liam M.; Stamboulis, Artemis

    2013-01-01

    Active screen plasma nitriding (ASPN) is a well-established technique used for the surface modification of materials, the result of which is often a product with enhanced functional performance. Here we report the modification of the chemical and mechanical properties of ultra-high molecular weight poly(ethylene) (UHMWPE) using 80:20 (v/v) N 2 /H 2 ASPN, followed by growth of 3T3 fibroblasts on the treated and untreated polymer surfaces. ASPN-treated UHMWPE showed extensive fibroblast attachment within 3 h of seeding, whereas fibroblasts did not successfully attach to untreated UHMWPE. Fibroblast-coated surfaces were maintained for up to 28 days, monitoring their metabolic activity and morphology throughout. The chemical properties of the ASPN-treated UHMWPE surface were studied using X-ray photoelectron spectroscopy, revealing the presence of C-N, C=N, and C≡N chemical bonds. The elastic modulus, surface topography, and adhesion properties of the ASPN-treated UHMWPE surface were studied over 28 days during sample storage under ambient conditions and during immersion in two commonly used cell culture media.

  18. Effects of geomagnetic storm on low latitude ionospheric total ...

    Indian Academy of Sciences (India)

    1Department of Physics, Tripura University, Suryamaninagar, Tripura 799 022, India. ... the fact that the electro-dynamic effect of geomagnetic storms around EIA region is more effective than ... causes range of error in GPS communication.

  19. Research on Stealthy Headphone Detector Based on Geomagnetic Sensor

    Directory of Open Access Journals (Sweden)

    Liu Ya

    2016-01-01

    Full Text Available A kind of stealth headphone detector based on geomagnetic sensor has been developed to deal with the stealth headphones which are small, extremely stealthy and hard to detect. The U.S. PNI geomagnetic sensor is chosen to obtain magnetic field considering the strong magnetic performance of stealth headphones. The earth’s magnetic field at the geomagnetic sensor is eliminated by difference between two geomagnetic sensors, and then weak variations of magnetic field is detected. STM8S103K2 is chosen as the central controlling chip, which is connected to LED, buzzer and LCD 1602. As shown by the experimental results, the probe is not liable to damage by the magnetic field and the developed device has high sensitivity, low False Positive Rate (FAR and satisfactory reliability.

  20. A comprehensive analysis of the geomagnetic storms occurred dur

    Directory of Open Access Journals (Sweden)

    Essam Ghamry

    2016-06-01

    Full Text Available The Geomagnetic storms are considered as one of the major natural hazards. Egyptian geomagnetic observatories observed multiple geomagnetic storms during 18 February to 2 March 2014. During this period, four interplanetary shocks successively hit the Earth’s magnetosphere, leading to four geomagnetic storms. The storm onsets occurred on 18, 20, 23 and 27 February. A non-substorm Pi2 pulsation was observed on 26 February. This Pi2 pulsation was detected in Egyptian observatories (Misallat and Abu Simbel, Kakioka station in Japan and Carson City station in US with nearly identical waveforms. Van Allen Probe missions observed non-compressional Pc4 pulsations on the recovery phase of the third storm. This Pc4 event is may be likely attributed to the decay of the ring current in the recovery phase.

  1. A Probabilistic Assessment of the Next Geomagnetic Reversal

    Science.gov (United States)

    Buffett, Bruce; Davis, William

    2018-02-01

    Deterministic forecasts for the next geomagnetic reversal are not feasible due to large uncertainties in the present-day state of the Earth's core. A more practical approach relies on probabilistic assessments using paleomagnetic observations to characterize the amplitude of fluctuations in the geomagnetic dipole. We use paleomagnetic observations for the past 2 Myr to construct a stochastic model for the axial dipole field and apply well-established methods to evaluate the probability of the next geomagnetic reversal as a function of time. For a present-day axial dipole moment of 7.6 × 1022 A m2, the probability of the dipole entering a reversed state is less than 2% after 20 kyr. This probability rises to 11% after 50 kyr. An imminent geomagnetic reversal is not supported by paleomagnetic observations. The current rate of decline in the dipole moment is unusual but within the natural variability predicted by the stochastic model.

  2. An Impending geomagnetic transition? Hints from the past.

    Directory of Open Access Journals (Sweden)

    Carlo eLAJ

    2015-10-01

    Full Text Available The rapid decrease of the geomagnetic field intensity in the last centuries has led to speculations that an attempt to a reversal or an excursion might be under way. Here we investigate this hypothesis by examining past records of geomagnetic field intensity obtained from sedimentary cores and from the study of cosmogenic nuclides. The selected records describe geomagnetic changes with an unprecedented temporal resolution between 20 and 75 kyr B.P. We find that some aspects of the present-day geomagnetic field have some similarities with those documented for the Laschamp excursion 41 kyr ago. Under the assumption that the dynamo processes for an eventual future reversal or excursion would be similar to those of the Laschamp excursion, we tentatively suggest that, whilst irreversible processes that will drive the geodynamo into a polarity change may have already started, a reversal or an excursion should not be expected before 500 to 1000 years.

  3. Characteristic features of the geomagnetic field of the Earth

    International Nuclear Information System (INIS)

    Petrova, G.N.

    1978-01-01

    The laws of the earth magnetism permitting to make a model of the earth magnetic field are popularly investigated. The modern methods of investigations used in the development of geomagnetism and determining the quantity and direction of the earth magnetic field from the moment of rock formation are described. Considered are the characteristic peculiarities of geomagnetic field: the inclination of the magnetic axis to the rotational axis of the Earth, the western drift of the geomagnetic field, the magnetic field asymmetry, its pole exchange and secular variations. The sources of the continuous magnetic field are investigated. The theory of hydromagnatic dinamo operating in the earth core is described. According to the invariance of the geomagnetic field characteristics it is possible to assume that the core has not significantly evolved for milliard years

  4. Porous platinum mesoflowers with enhanced activity for methanol oxidation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang Lina; Wang Wenjin; Hong Feng [School of Science, MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Xi' an Jiaotong University, Xi' an 710049 (China); Yang Shengchun, E-mail: ysch1209@mail.xjtu.edu.cn [School of Science, MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Xi' an Jiaotong University, Xi' an 710049 (China); You Hongjun, E-mail: hjyou@mail.xjtu.edu.cn [School of Science, MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Xi' an Jiaotong University, Xi' an 710049 (China); Fang Jixiang; Ding Bingjun [School of Science, MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Xi' an Jiaotong University, Xi' an 710049 (China)

    2012-07-15

    Porous Pt and Pt-Ag alloy mesoflowers (MFs) with about 2 {mu}m in diameter and high porosity were synthesized using Ag mesoflowers as sacrificial template by galvanic reaction. The silver content in Pt-Ag alloys can be facilely controlled by nitric acid treatment. And the pure Pt MFs can be obtained by selective removal of silver element from Pt{sub 72}Ag{sub 28} MFs electrochemically. Both Pt{sub 45}Ag{sub 55}, Pt{sub 72}Ag{sub 28} and pure Pt show a high catalytic performance in methanol oxidation reaction (MOR). Especially, pure Pt MFs exhibited a 2 to 3 times current density enhancement in MOR compared with the commercial used Pt black, which can be attributed to their porous nanostructure with 3-dimentional nature and small crystal sizes. - Graphical Abstract: The CVs of MOR on Pt (red) and Pt black (green) catalysts in 0.1 M HClO{sub 4} and 0.5 M CH{sub 3}OH for specific mass current. The insert shows the SEM images of two porous Pt MFs. Platinum mesoflowers (MFs) with about 2 {mu}m in diameter and high porosity were synthesised with Ag mesoflowers as sacrificial template by galvanic replacement. The porous Pt MFs exhibited a more than 3 times enhancement in electrocatalytic performance for methanol oxidation reaction compared the commercial used Pt black. Highlights: Black-Right-Pointing-Pointer Porous Pt and Pt-Ag mesoflowers (MFs) were synthesized using Ag MFs sacrifical template. Black-Right-Pointing-Pointer Pt MFs presents an improved catalytic activity in MOR compared with Pt black. Black-Right-Pointing-Pointer We provided a facile approach for the development of high performance Pt electrocatalysts for fuel cells.

  5. Geomagnetic field models for satellite angular motion studies

    Science.gov (United States)

    Ovchinnikov, M. Yu.; Penkov, V. I.; Roldugin, D. S.; Pichuzhkina, A. V.

    2018-03-01

    Four geomagnetic field models are discussed: IGRF, inclined, direct and simplified dipoles. Geomagnetic induction vector expressions are provided in different reference frames. Induction vector behavior is compared for different models. Models applicability for the analysis of satellite motion is studied from theoretical and engineering perspectives. Relevant satellite dynamics analysis cases using analytical and numerical techniques are provided. These cases demonstrate the benefit of a certain model for a specific dynamics study. Recommendations for models usage are summarized in the end.

  6. A Probabilistic Assessment of the Next Geomagnetic Reversal

    OpenAIRE

    Buffett, B; Davis, W

    2018-01-01

    ©2018. American Geophysical Union. All Rights Reserved. Deterministic forecasts for the next geomagnetic reversal are not feasible due to large uncertainties in the present-day state of the Earth's core. A more practical approach relies on probabilistic assessments using paleomagnetic observations to characterize the amplitude of fluctuations in the geomagnetic dipole. We use paleomagnetic observations for the past 2 Myr to construct a stochastic model for the axial dipole field and apply wel...

  7. Properties of Pliocene sedimentary geomagnetic reversal records from the Mediterranean

    OpenAIRE

    Linssen, J.H.

    1991-01-01

    In the history of the Earth the dipolar geomagnetic field has frequently reversed polarity. Though this property was already known early this century (Brunhes, 1906), nowadays the characteristics and the origin of polarity transitions are still largely unknown. The geomagnetic field and its variations are recorded in rocks as a natural remanent magnetization (NRM) during the formation of these rocks. The study of the NRM in sedimentary reversal records is the subject of this dissertation.

  8. Anomalous short period geomagnetic variations at two stations in Sri Lanka

    International Nuclear Information System (INIS)

    Kunaratnam, K.

    1986-08-01

    An analysis of the rates of change in the geomagnetic field components in the period range 20-600 sec recorded at Kondavil and Hikkaduwa, two stations in the equatorial electrojet belt near the northern and south western coasts respectively of Sri Lanka, shows anomalous variations. The results confirm induced current concentration in the Palk Strait and deflection of induced currents around the southerncoast of Sri Lanka postulated by earlier workers from observations of SSC and Bay events at Indian stations and from analogue and numerical model studies. At Kondavil, which is situated close to the geomagnetic equator, no appreciable difference in the night-time and day-time values of ΔZ/ΔH and ΔD/ΔH ratios was noticed while at Hikkaduwa, a station situated under the edge of the equatorial electrojet belt, a day-time enhancement of ΔZ/ΔH ratios was found at all periods in the observed range. An enhancement of the H component at Colombo over that at Hikkaduwa was also found at short periods, the enhancement being greater at day-time. The day-time enhancement in the ΔZ/ΔH ratios at Hikkaduwa and in the ratio of the H components at Colombo and Hikkaduwa could be due to the effect of the equatorial electrojet on the short period variations. (author)

  9. Radar meteor rates and solar activity

    International Nuclear Information System (INIS)

    Prikryl, P.

    1983-01-01

    The short-term variation of diurnal radar meteor rates with solar activity represented by solar microwave flux Fsub(10.7), and sunspots relative number Rsub(z), is investigated. Applying the superposed-epoch analysis to the observational material of radar meteor rates from Christchurch (1960-61 and 1963-65), a decrease in the recorded radar rates is found during days of enhanced solar activity. No effect of geomagnetic activity similar to the one reported for the Swedish and Canadian radar meteor data was found by the author in the Christchurch data. A possible explanation of the absence of the geomagnetic effect on radar meteor rates from New Zealand due to a lower echo ceiling height of the Christchurch radar is suggested. The variation of the atmospheric parameters as a possible cause of the observed variation in radar meteor rates is also discussed. (author)

  10. Automated detection of geomagnetic storms with heightened risk of GIC

    Science.gov (United States)

    Bailey, Rachel L.; Leonhardt, Roman

    2016-06-01

    Automated detection of geomagnetic storms is of growing importance to operators of technical infrastructure (e.g., power grids, satellites), which is susceptible to damage caused by the consequences of geomagnetic storms. In this study, we compare three methods for automated geomagnetic storm detection: a method analyzing the first derivative of the geomagnetic variations, another looking at the Akaike information criterion, and a third using multi-resolution analysis of the maximal overlap discrete wavelet transform of the variations. These detection methods are used in combination with an algorithm for the detection of coronal mass ejection shock fronts in ACE solar wind data prior to the storm arrival on Earth as an additional constraint for possible storm detection. The maximal overlap discrete wavelet transform is found to be the most accurate of the detection methods. The final storm detection software, implementing analysis of both satellite solar wind and geomagnetic ground data, detects 14 of 15 more powerful geomagnetic storms over a period of 2 years.

  11. The postsunset vertical plasma drift during geomagnetic storms and its effects on the generation of equatorial spread F

    Science.gov (United States)

    Huang, C.

    2017-12-01

    We will present two distinct phenomena related to the postsunset vertical plasma drift and equatorial spread F (ESF) observed by the Communication/Navigation Outage Forecasting System satellite over six years. The first phenomenon is the behavior of the prereversal enhancement (PRE) of the vertical plasma drift during geomagnetic storms. Statistically, storm-time disturbance dynamo electric fields cause the PRE to decrease from 30 to 0 m/s when Dst changes from -60 to -100 nT, but the PRE does not show obvious variations when Dst varies from 0 to -60 nT. The observations show that the storm activities affect the evening equatorial ionosphere only for Dst correlated with the PRE and that the occurrence of small-amplitude ESF irregularities does not show a clear pattern at low solar activity but is anti-correlated with large-amplitude irregularities and the PRE at moderate solar activity. That is, the months and longitudes with high occurrence probability of large-amplitude irregularities are exactly those with low occurrence probability of small-amplitude irregularities, and vice versa. The generation of large-amplitude ESF irregularities is controlled by the PRE, and the generation of small-amplitude ESF irregularities may be caused by gravity waves and other disturbances, rather than by the PRE.

  12. Enhanced biological activities of gamma-irradiated persimmon leaf extract.

    Science.gov (United States)

    Cho, Byoung-Ok; Nchang Che, Denis; Yin, Hong-Hua; Jang, Seon-Il

    2017-09-01

    The aim of this study was to compare the anti-oxidative and anti-inflammatory activities of gamma-irradiated persimmon leaf extract (GPLE) with those of non-irradiated persimmon leaf extract (PLE). Ethanolic extract of persimmon leaf was exposed to gamma irradiation at a dose of 10 kGy. After gamma irradiation, the color of the extract changed from dark brown to light brown. The anti-oxidative and anti-inflammatory activities of GPLE and PLE were assessed from: total polyphenol and total flavonoid contents; 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay; 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assay, and levels of pro-inflammatory mediators such as nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). The total polyphenol contents of GPLE and PLE were determined to be 224.44 ± 1.54 and 197.33 ± 5.81 mg gallic acid equivalents (GAE)/g, respectively, and the total flavonoid contents of GPLE and PLE were 206.27 ± 1.15 and 167.60 ± 2.00 mg quercetin equivalents (QUE)/g, respectively. The anti-oxidant activities of GPLE and PLE as measured by DPPH assays were 338.33 ± 30.19 μg/ml (IC50) and 388.68 ± 8.45 μg/ml (IC50), respectively, and those measured by ABTS assays were 510.49 ± 15.12 μg/ml (IC50) and 731.30 ± 10.63 μg/ml (IC50), respectively. IC50 is the inhibitor concentration that reduces the response by 50%. GPLE strongly inhibited the production of NO, PGE2 and IL-6 compared with PLE in lipopolysaccharide-stimulated RAW264.7 macrophages. Furthermore, GPLE significantly inhibited the production of TNF-α and IL-6 cytokines compared with PLE in phorbol 12-myristate 13-acetate (PMA) plus A23187-stimulated HMC-1 human mast cells. These results indicate that gamma irradiation of PLE can enhance its anti-oxidative and anti-inflammatory activities through elevation of the phenolic contents. Therefore, gamma-irradiated PLE has potential for use in the food and cosmetic

  13. A Carrington-like geomagnetic storm observed in the 21st century

    Directory of Open Access Journals (Sweden)

    Cid Consuelo

    2015-01-01

    Full Text Available In September 1859 the Colaba observatory measured the most extreme geomagnetic disturbance ever recorded at low latitudes related to solar activity: the Carrington storm. This paper describes a geomagnetic disturbance case with a profile extraordinarily similar to the disturbance of the Carrington event at Colaba: the event on 29 October 2003 at Tihany magnetic observatory in Hungary. The analysis of the H-field at different locations during the “Carrington-like” event leads to a re-interpretation of the 1859 event. The major conclusions of the paper are the following: (a the global Dst or SYM-H, as indices based on averaging, missed the largest geomagnetic disturbance in the 29 October 2003 event and might have missed the 1859 disturbance, since the large spike in the horizontal component (H of terrestrial magnetic field depends strongly on magnetic local time (MLT; (b the main cause of the large drop in H recorded at Colaba during the Carrington storm was not the ring current but field-aligned currents (FACs; and (c the very local signatures of the H-spike imply that a Carrington-like event can occur more often than expected.

  14. Predicting geomagnetic storms from solar-wind data using time-delay neural networks

    Directory of Open Access Journals (Sweden)

    H. Gleisner

    1996-07-01

    Full Text Available We have used time-delay feed-forward neural networks to compute the geomagnetic-activity index Dst one hour ahead from a temporal sequence of solar-wind data. The input data include solar-wind density n, velocity V and the southward component Bz of the interplanetary magnetic field. Dst is not included in the input data. The networks implement an explicit functional relationship between the solar wind and the geomagnetic disturbance, including both direct and time-delayed non-linear relations. In this study we especially consider the influence of varying the temporal size of the input-data sequence. The networks are trained on data covering 6600 h, and tested on data covering 2100 h. It is found that the initial and main phases of geomagnetic storms are well predicted, almost independent of the length of the input-data sequence. However, to predict the recovery phase, we have to use up to 20 h of solar-wind input data. The recovery phase is mainly governed by the ring-current loss processes, and is very much dependent on the ring-current history, and thus also the solar-wind history. With due consideration of the time history when optimizing the networks, we can reproduce 84% of the Dst variance.

  15. Nanostructured porous ZnO film with enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Wang Lina; Zheng Yingying; Li Xiaoyun; Dong Wenjun; Tang Weihua; Chen Benyong; Li Chaorong; Li Xiao; Zhang Tierui

    2011-01-01

    Well-defined ZnO nanostructured films have been fabricated directly on Zn foil via hydrothermal synthesis. During the fabrication of the ZnO nanostructured films, the Zn foil serves as the Zn source and also the substrate. Porous nanosheet-based, nanotube-based and nanoflower-based ZnO films can all be easily prepared by adjusting the alkali type, reaction time and reaction temperature. The composition, morphology and structure of ZnO films are characterized by X-ray diffraction, scanning electron microscope and high-resolution transmission electron microscope. The porous ZnO nanosheet-based film exhibits enhanced photocatalytic activity in the degradation of Rhodamine B under UV light irradiation. This can be attributed to the high surface area of the ZnO nanosheet and the large percentage of the exposed [001] facet. Moreover, the self-supporting, recyclable and stable ZnO photocatalytic film can be readily recovered and potentially applied for pollution disposal.

  16. Optical manipulation and catalytic activity enhanced by surface plasmon effect

    Science.gov (United States)

    Zou, Ningmu; Min, Jiang; Jiao, Wenxiang; Wang, Guanghui

    2017-02-01

    For optical manipulation, a nano-optical conveyor belt consisting of an array of gold plasmonic non-concentric nano-rings (PNNRs) is demonstrated for the realization of trapping and unidirectional transportation of nanoparticles by polarization rotation of excitation beam. These hot spots of an asymmetric plasmonic nanostructure are polarization dependent, therefore, one can use the incident polarization state to manipulate the trapped targets. Trapped particles could be transferred between adjacent PNNRs in a given direction just by rotating the polarization of incident beam due to unbalanced potential. The angular dependent distribution of electric field around PNNR has been solved using the three- dimensional finite-difference time-domain (FDTD) technique. For optical enhanced catalytic activity, the spectral properties of dimers of Au nanorod-Au nanorod nanostructures under the excitation of 532nm photons have been investigated. With a super-resolution catalytic mapping technique, we identified the existence of "hot spot" in terms of catalytic reactivity at the gap region within the twined plasmonic nanostructure. Also, FDTD calculation has revealed an intrinsic correlation between hot electron transfer.

  17. Eugenol nanocapsule for enhanced therapeutic activity against periodontal infections.

    Science.gov (United States)

    Pramod, Kannissery; Aji Alex, M R; Singh, Manisha; Dang, Shweta; Ansari, Shahid H; Ali, Javed

    2016-01-01

    Eugenol is a godsend to dental care due to its analgesic, local anesthetic, and anti-inflammatory and antibacterial effects. The aim of the present research work was to prepare, characterize and evaluate eugenol-loaded nanocapsules (NCs) against periodontal infections. Eugenol-loaded polycaprolactone (PCL) NCs were prepared by solvent displacement method. The nanometric size of the prepared NCs was confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The in vitro drug release was found to follow a biphasic pattern and followed Michaelis-Menten like model. The percentage cell viability values near to 100 in the cell viability assay indicated that the NCs are not cytotoxic. In the in vivo studies, the eugenol NC group displayed significant difference in the continuity of epithelium of the interdental papilla in comparison to the untreated, pure eugenol and placebo groups. The in vivo performance of the eugenol-loaded NCs using ligature-induced periodontitis model in rats indicated that eugenol-loaded NCs could prevent septal bone resorption in periodontitis. On the basis of our research findings it could be concluded that eugenol-loaded PCL NCs could serve as a novel colloidal drug delivery system for enhanced therapeutic activity of eugenol in the treatment of periodontal infections.

  18. Does small-bodied salmon spawning activity enhance streambed mobility?

    Science.gov (United States)

    Hassan, Marwan A.; Tonina, Daniele; Buxton, Todd H.

    2015-09-01

    Female salmonids bury and lay their eggs in streambeds by digging a pit, which is then covered with sediment from a second pit that is dug immediately upstream. The spawning process alters streambed topography, winnows fine sediment, and mixes sediment in the active layer. The resulting egg nests (redds) contain coarser and looser sediments than those of unspawned streambed areas, and display a dune-like shape with an amplitude and length that vary with fish size, substrate conditions, and flow conditions. Redds increase local bed surface roughness (drag, resulting in lower grain shear stress and less particle mobility. Spawning, also prevents streambed armoring by mixing surface and subsurface material, potentially increasing particle mobility. Here we use two-dimensional hydraulic modeling with detailed prespawning and postspawning bathymetries and field observations to test the effect of spawning by small-bodied salmonids on sediment transport. Our results show that topographical roughness from small salmon redds has negligible effects on shear stress at the reach-unit scale, and limited effects at the local scale. Conversely, results indicate sediment mixing reduces armoring and enhances sediment mobility, which increases potential bed load transport by subsequent floods. River restoration in fish-bearing streams should take into consideration the effects of redd excavation on channel stability. This is particularly important for streams that historically supported salmonids and are the focus of habitat restoration actions.

  19. Photon activation therapy: a Monte Carlo study on dose enhancement by various sources and activation media

    International Nuclear Information System (INIS)

    Bakhshabadi, Mahdi; Ghorbani, Mahdi; Meigooni, Ali Soleimani

    2013-01-01

    In the present study, a number of brachytherapy sources and activation media were simulated using MCNPX code and the results were analyzed based on the dose enhancement factor values. Furthermore, two new brachytherapy sources ( 131 Cs and a hypothetical 170 Tm) were evaluated for their application in photon activation therapy (PAT). 125 I, 103 Pd, 131 Cs and hypothetical 170 Tm brachytherapy sources were simulated in water and their dose rate constant and the radial dose functions were compared with previously published data. The sources were then simulated in a soft tissue phantom which was composed of Ag, I, Pt or Au as activation media uniformly distributed in the tumour volume. These simulations were performed using the MCNPX code, and dose enhancement factor (DEF) was obtained for 7, 18 and 30 mg/ml concentrations of the activation media. Each source, activation medium and concentration was evaluated separately in a separate simulation. The calculated dose rate constant and radial dose functions were in agreement with the published data for the aforementioned sources. The maximum DEF was found to be 5.58 for a combination of the 170 Tm source with 30 mg/ml concentration of I. The DEFs for 131 Cs and 170 Tm sources for all the four activation media were higher than those for other sources and activation media. From this point of view, these two sources can be more useful in photon activation therapy with photon emitter sources. Furthermore, 131 Cs and 170 Tm brachytherapy sources can be proposed as new options for use in the field of PAT.

  20. Enhanced persistency of resting and active periods of locomotor activity in schizophrenia.

    Directory of Open Access Journals (Sweden)

    Wataru Sano

    Full Text Available Patients with schizophrenia frequently exhibit behavioral abnormalities associated with its pathological symptoms. Therefore, a quantitative evaluation of behavioral dynamics could contribute to objective diagnoses of schizophrenia. However, such an approach has not been fully established because of the absence of quantitative biobehavioral measures. Recently, we studied the dynamical properties of locomotor activity, specifically how resting and active periods are interwoven in daily life. We discovered universal statistical laws ("behavioral organization" and their alterations in patients with major depressive disorder. In this study, we evaluated behavioral organization of schizophrenic patients (n = 19 and healthy subjects (n = 11 using locomotor activity data, acquired by actigraphy, to investigate whether the laws could provide objective and quantitative measures for a possible diagnosis and assessment of symptoms. Specifically, we evaluated the cumulative distributions of resting and active periods, defined as the periods with physical activity counts successively below and above a predefined threshold, respectively. Here we report alterations in the laws governing resting and active periods; resting periods obeyed a power-law cumulative distribution with significantly lower parameter values (power-law scaling exponents, whereas active periods followed a stretched exponential distribution with significantly lower parameter values (stretching exponents, in patients. Our findings indicate enhanced persistency of both lower and higher locomotor activity periods in patients with schizophrenia, probably reflecting schizophrenic pathophysiology.

  1. Regulation of hepatitis B virus ENI enhancer activity by hepatocyte-enriched transcription factor HNF3.

    Science.gov (United States)

    Chen, M; Hieng, S; Qian, X; Costa, R; Ou, J H

    1994-11-15

    Hepatitis B virus (HBV) ENI enhancer can activate the expression of HBV and non-HBV genes in a liver-specific manner. By performing the electrophoretic mobility-shift assays, we demonstrated that the three related, liver-enriched, transcription factors, HNF3 alpha, HNF3 beta, and HNF3 gamma could all bind to the 2c site of HBV ENI enhancer. Mutations introduced in the 2c site to abolish the binding by HNF3 reduced the enhancer activity approximately 15-fold. Moreover, expression of HNF3 antisense sequences to suppress the expression of HNF3 in Huh-7 hepatoma cells led to reduction of the ENI enhancer activity. These results indicate that HNF3 positively regulates the ENI enhancer activity and this regulation is most likely mediated through the 2c site. The requirement of HNF3 for the ENI enhancer activity could explain the liver specificity of this enhancer element.

  2. Average configuration of the geomagnetic tail

    International Nuclear Information System (INIS)

    Fairfield, D.H.

    1979-01-01

    Over 3000 hours of Imp 6 magnetic field data obtained between 20 and 33 R/sub E/ in the geomagnetic tail have been used in a statistical study of the tail configuration. A distribution of 2.5-min averages of B/sub z/ as a function of position across the tail reveals that more flux crosses the equatorial plane near the dawn and dusk flanks (B-bar/sub z/=3.γ) than near midnight (B-bar/sub z/=1.8γ). The tail field projected in the solar magnetospheric equatorial plane deviates from the x axis due to flaring and solar wind aberration by an angle α=-0.9 Y/sub SM/-2.7, where Y/sub SM/ is in earth radii and α is in degrees. After removing these effects, the B/sub y/ component of the tail field is found to depend on interplanetary sector structure. During an 'away' sector the B/sub y/ component of the tail field is on average 0.5γ greater than that during a 'toward' sector, a result that is true in both tail lobes and is independent of location across the tail. This effect means the average field reversal between northern and southern lobes of the tail is more often 178 0 rather than the 180 0 that is generally supposed

  3. Design of New Antibacterial Enhancers Based on AcrB’s Structure and the Evaluation of Their Antibacterial Enhancement Activity

    Directory of Open Access Journals (Sweden)

    Yi Song

    2016-11-01

    Full Text Available Previously, artesunate (AS and dihydroartemisinine 7 (DHA7 were found to have antibacterial enhancement activity against Escherichia coli via inhibition of the efflux pump AcrB. However, they were only effective against E. coli standard strains. This study aimed to develop effective antibacterial enhancers based on the previous work. Our results demonstrate that 86 new antibacterial enhancers were designed via 3D-SAR and molecular docking. Among them, DHA27 had the best antibacterial enhancement activity. It could potentiate the antibacterial effects of ampicillin against not only E. coli standard strain but also clinical strains, and of β-lactam antibiotics, not non-β-lactamantibiotics. DHA27 could increase the accumulation of daunomycin and nile red within E. coli ATCC 35218, but did not increase the bacterial membrane permeability. DHA27 reduced acrB’s mRNA expression of E. coli ATCC 35218 in a dose-dependent manner, and its antibacterial enhancement activity is related to the degree of acrB mRNA expression in E. coli clinical strains. The polypeptides from AcrB were obtained via molecular docking assay; the pre-incubated polypeptides could inhibit the activity of DHA27. Importantly, DHA27 had no cytotoxicity on cell proliferation. In conclusion, among newly designed antibacterial enhancers, DHA27 had favorable physical and pharmacological properties with no significant cytotoxicity at effective concentrations, and might serve as a potential efflux pump inhibitor in the future.

  4. Activation of the polyomavirus enhancer by a murine activator protein 1 (AP1) homolog and two contiguous proteins.

    OpenAIRE

    Martin, M E; Piette, J; Yaniv, M; Tang, W J; Folk, W R

    1988-01-01

    The polyomavirus enhancer is composed of multiple DNA sequence elements serving as binding sites for proteins present in mouse nuclear extracts that activate transcription and DNA replication. We have identified three such proteins and their binding sites and correlate them with enhancer function. Mutation of nucleotide (nt) 5140 in the enhancer alters the binding site (TGACTAA, nt 5139-5145) for polyomavirus enhancer A binding protein 1 (PEA1), a murine homolog of the human transcription fac...

  5. Glutamate transporter activity promotes enhanced Na+/K+-ATPase -mediated extracellular K+ management during neuronal activity

    DEFF Research Database (Denmark)

    Larsen, Brian R; Holm, Rikke; Vilsen, Bente

    2016-01-01

    , in addition, Na+ /K+ -ATPase-mediated K+ clearance could be governed by astrocytic [Na+ ]i . During most neuronal activity, glutamate is released in the synaptic cleft and is re-absorbed by astrocytic Na+ -coupled glutamate transporters, thereby elevating [Na+ ]i . It thus remains unresolved whether...... the different Na+ /K+ -ATPase isoforms are controlled by [K+ ]o or [Na+ ]i during neuronal activity. Hippocampal slice recordings of stimulus-induced [K+ ]o transients with ion-sensitive microelectrodes revealed reduced Na+ /K+ -ATPase-mediated K+ management upon parallel inhibition of the glutamate transporter......+ affinity to the α1 and α2 isoforms than the β2 isoform. In summary, enhanced astrocytic Na+ /K+ -ATPase-dependent K+ clearance was obtained with parallel glutamate transport activity. The astrocytic Na+ /K+ -ATPase isoform constellation α2β1 appeared to be specifically geared to respond to the [Na+ ]i...

  6. Transitional geomagnetic impulse hypothesis: Geomagnetic fact or rock-magnetic artifact?

    Science.gov (United States)

    Camps, Pierre; Coe, Robert S.; PréVot, Michel

    1999-08-01

    A striking feature of the Steens Mountain (Oregon) geomagnetic polarity reversal is the two (maybe three) extremely rapid field directional changes (6 degrees per day) proposed to account for unusual behavior in direction of remanent magnetization in a single lava flow. Each of these very fast field changes, or impulses, is associated with a large directional gap (some 90°) in the record. In order to check the spatial reproducibility of the paleomagnetic signal over distances up to several kilometers, we have carried out a paleomagnetic investigation of two new sections (B and F) in the Steens summit region which cover the second and the third directional gap. The main result is the description of two new directions, which are located between the pre second and post second impulse directions. These findings weigh against the hypothesis that the geomagnetic field cause the unusual intraflow fluctuations, which now appears to be more ad hoc as an explanation of the paleomagnetic data. However, the alternative baking hypothesis remains also ad hoc since we have to assume variable rock magnetic properties that we have not yet been able to detect within the flows at the original section Steens A and D 1.5 km to the north. In addition, new results for 22 transitional and normal lava flows in section B are presented that correlate well with earlier results from section A.

  7. A study of geomagnetic field variations along the 80° S geomagnetic parallel

    Directory of Open Access Journals (Sweden)

    S. Lepidi

    2017-01-01

    Full Text Available The availability of measurements of the geomagnetic field variations in Antarctica at three sites along the 80° S geomagnetic parallel, separated by approximately 1 h in magnetic local time, allows us to study the longitudinal dependence of the observed variations. In particular, using 1 min data from Mario Zucchelli Station, Scott Base and Talos Dome, a temporary installation during 2007–2008 Antarctic campaign, we investigated the diurnal variation and the low-frequency fluctuations (approximately in the Pc5 range, ∼ 1–7 mHz. We found that the daily variation is clearly ordered by local time, suggesting a predominant effect of the polar extension of midlatitude ionospheric currents. On the other hand, the pulsation power is dependent on magnetic local time maximizing around magnetic local noon, when the stations are closer to the polar cusp, while the highest coherence between pairs of stations is observed in the magnetic local nighttime sector. The wave propagation direction observed during selected events, one around local magnetic noon and the other around local magnetic midnight, is consistent with a solar-wind-driven source in the daytime and with substorm-associated processes in the nighttime.

  8. Novel ST-MUSIC-based spectral analysis for detection of ULF geomagnetic signals anomalies associated with seismic events in Mexico

    Directory of Open Access Journals (Sweden)

    Omar Chavez

    2016-05-01

    Full Text Available Recently, the analysis of ultra-low-frequency (ULF geomagnetic signals in order to detect seismic anomalies has been reported in several works. Yet, they, although having promising results, present problems for their detection since these anomalies are generally too much weak and embedded in high noise levels. In this work, a short-time multiple signal classification (ST-MUSIC, which is a technique with high-frequency resolution and noise immunity, is proposed for the detection of seismic anomalies in the ULF geomagnetic signals. Besides, the energy (E of geomagnetic signals processed by ST-MUSIC is also presented as a complementary parameter to measure the fluctuations between seismic activity and seismic calm period. The usefulness and effectiveness of the proposal are demonstrated through the analysis of a synthetic signal and five real signals with earthquakes. The analysed ULF geomagnetic signals have been obtained using a tri-axial fluxgate magnetometer at the Juriquilla station, which is localized in Queretaro, Mexico (geographic coordinates: longitude 100.45° E and latitude 20.70° N. The results obtained show the detection of seismic perturbations before, during, and after the main shock, making the proposal a suitable tool for detecting seismic precursors.

  9. Empirical model of TEC response to geomagnetic and solar forcing over Balkan Peninsula

    Science.gov (United States)

    Mukhtarov, P.; Andonov, B.; Pancheva, D.

    2018-01-01

    An empirical total electron content (TEC) model response to external forcing over Balkan Peninsula (35°N-50°N; 15°E-30°E) is built by using the Center for Orbit Determination of Europe (CODE) TEC data for full 17 years, January 1999 - December 2015. The external forcing includes geomagnetic activity described by the Kp-index and solar activity described by the solar radio flux F10.7. The model describes the most probable spatial distribution and temporal variability of the externally forced TEC anomalies assuming that they depend mainly on latitude, Kp-index, F10.7 and LT. The anomalies are expressed by the relative deviation of the TEC from its 15-day mean, rTEC, as the mean value is calculated from the 15 preceding days. The approach for building this regional model is similar to that of the global TEC model reported by Mukhtarov et al. (2013a) however it includes two important improvements related to short-term variability of the solar activity and amended geomagnetic forcing by using a "modified" Kp index. The quality assessment of the new constructing model procedure in terms of modeling error calculated for the period of 1999-2015 indicates significant improvement in accordance with the global TEC model (Mukhtarov et al., 2013a). The short-term prediction capabilities of the model based on the error calculations for 2016 are improved as well. In order to demonstrate how the model is able to reproduce the rTEC response to external forcing three geomagnetic storms, accompanied also with short-term solar activity variations, which occur at different seasons and solar activity conditions are presented.

  10. Improving geomagnetic observatory data in the South Atlantic Anomaly

    Science.gov (United States)

    Matzka, Jürgen; Morschhauser, Achim; Brando Soares, Gabriel; Pinheiro, Katia

    2016-04-01

    The Swarm mission clearly proofs the benefit of coordinated geomagnetic measurements from a well-tailored constellation in order to recover as good as possible the contributions of the various geomagnetic field sources. A similar truth applies to geomagnetic observatories. Their scientific value can be maximised by properly arranging the position of individual observatories with respect to the geometry of the external current systems in the ionosphere and magnetosphere, with respect to regions of particular interest for secular variation, and with respect to regions of anomalous electric conductivity in the ground. Here, we report on our plans and recent efforts to upgrade geomagnetic observatories and to recover unpublished data from geomagnetic observatories at low latitudes in the South Atlantic Anomaly. In particular, we target the magnetic equator with the equatorial electrojet and low latitudes to characterise the Sq- and ring current. The observatory network that we present allows also to study the longitudinal structure of these external current systems. The South Atlantic Anomaly region is very interesting due to its secular variation. We will show newly recovered data and comparisons with existing data sets. On the technical side, we introduce low-power data loggers. In addition, we use mobile phone data transfer, which is rapidly evolving in the region and allows timely data access and quality control at remote sites that previously were not connected to the internet.

  11. Environmental and geomagnetic factors in relation to self-destructive ideation and behaviour

    Science.gov (United States)

    Bergiannaki, J. D.; Psarros, C.; Nastos, P. Th.; Paparigopoulos, T.; Paliatsos, A. G.; Tritakis, V. P.; Stefanis, C. N.

    2001-09-01

    Besides the individual factors such as the reaction to conflicts, several exogenous factors environmental and social may exert a pathogenic influence on suicidal behavior, suicide attempts and complete suicide on predisposed individuals. In the turn of the century many reports accord for the seasonality of suicides, which seems to have a bimodal distribution with a major peak around the spring-summer (April-May) and a second minor in autumn. On the other hand, the seasonal variation of environmental factors (daylight, sunlight duration, weather, temperature, air pressure, humidity, geomagnetism, solar activity, etc), of biological factors (melatonin, serotonin, serotonin precursors, etc) as also of sociological factors (ethnic events, major holidays, weekends etc) possibly influences the seasonal pattern of self-destructive behavior. Bimodal seasonal variation is also reported for biochemical parameters (L-tryptophan, serotonin, endorphin I fraction) that matches seasonal pattern in the prevalence of violent suicide in the total population and also in the incidence of the affective disorders. The aim of this study is to investigate the relation of environmental factors expressed by the Discomfort Index (DI) and geomagnetic factors expressed by the geomagnetic field Index DST in relation to suicidal behavior. The total number (4803) of patients recorded in the Ambulance of a Phychiatric Hospital (Eginition) throughout 1994 was used along with the records of 2750 patients of the year 1989. The Index DI is a function of dry and wet-bulb temperature. DST is probably one of the geomagnetic indices that expresses and monitors with the greatest accuracy the equatorial ring current variations. Our results show that there is a seasonal variation of suicidal behavior (Fourier analysis) with a major peak during summer (July) and a minor one during spring. A difference in the occurrence of the peaks was observed among genders. A relation of self-destructive behavior and the

  12. Pre-storm NmF2 enhancements at middle latitudes: delusion or reality?

    Directory of Open Access Journals (Sweden)

    A. V. Mikhailov

    2009-03-01

    Full Text Available A critical analysis of recent publications devoted to the NmF2 pre-storm enhancements is performed. There are no convincing arguments that the observed cases of NmF2 enhancements at middle and sub-auroral latitudes bear a relation to the following magnetic storms. In all cases considered the NmF2 pre-storm enhancements were due to previous geomagnetic storms, moderate auroral activity or they presented the class of positive quiet time events (Q-disturbances. Therefore, it is possible to conclude that there is no such an effect as the pre-storm NmF2 enhancement as a phenomenon inalienably related to the following magnetic storm. The observed nighttime NmF2 enhancements at sub-auroral latitudes may result from plasma transfer from the plasma ring area by meridional thermospheric wind. Enhanced plasmaspheric fluxes into the nighttime F2-region resulted from westward substorm-associated electric fields is another possible source of nighttime NmF2 enhancements. Daytime positive Q-disturbances occurring under very low geomagnetic activity level may be related to the dayside cusp activity.

  13. Geomagnetic and strong static magnetic field effects on growth and chlorophyll a fluorescence in Lemna minor.

    Science.gov (United States)

    Jan, Luka; Fefer, Dušan; Košmelj, Katarina; Gaberščik, Alenka; Jerman, Igor

    2015-04-01

    The geomagnetic field (GMF) varies over Earth's surface and changes over time, but it is generally not considered as a factor that could influence plant growth. The effects of reduced and enhanced GMFs and a strong static magnetic field on growth and chlorophyll a (Chl a) fluorescence of Lemna minor plants were investigated under controlled conditions. A standard 7 day test was conducted in extreme geomagnetic environments of 4 µT and 100 µT as well as in a strong static magnetic field environment of 150 mT. Specific growth rates as well as slow and fast Chl a fluorescence kinetics were measured after 7 days incubation. The results, compared to those of controls, showed that the reduced GMF significantly stimulated growth rate of the total frond area in the magnetically treated plants. However, the enhanced GMF pointed towards inhibition of growth rate in exposed plants in comparison to control, but the difference was not statistically significant. This trend was not observed in the case of treatments with strong static magnetic fields. Our measurements suggest that the efficiency of photosystem II is not affected by variations in GMF. In contrast, the strong static magnetic field seems to have the potential to increase initial Chl a fluorescence and energy dissipation in Lemna minor plants. © 2015 Wiley Periodicals, Inc.

  14. F layer positive response to a geomagnetic storm - June 1972

    International Nuclear Information System (INIS)

    Miller, N.J.; Grebowsky, J.M.; Mayr, H.G.; Harris, I.; Tulunay, Y.K.

    1979-01-01

    A circulation model of neutral thermosphere-ionosphere coupling is used to interpret in situ spacecraft measurements taken during a topside mid-latitude ionospheric storm. The data are measurements of electron density taken along the circular polar orbit of Ariel 4 at 550 km during the geomagnetically disturbed period June 17--18, 1972. We infer that collisional momentum transfer from the disturbed neutral thermosphere to the ionosphere was the dominant midday process generating the positive F layer storm phase in the summer hemisphere. In the winter hemisphere the positive storm phase drifted poleward in apparent response to magnetospheric E x B drifts. A summer F layer positive phase developed at the sudden commencement and again during the geomagnetic main phase; a winter F layer positive phase developed only during the geomagnetic main phase. The observed seasonal differences in both the onsets and the magnitudes of the positive phases are attributed to the interhemispheric asymmetry in thermospheric dynamics

  15. Midlatitude cooling caused by geomagnetic field minimum during polarity reversal.

    Science.gov (United States)

    Kitaba, Ikuko; Hyodo, Masayuki; Katoh, Shigehiro; Dettman, David L; Sato, Hiroshi

    2013-01-22

    The climatic effects of cloud formation induced by galactic cosmic rays (CRs) has recently become a topic of much discussion. The CR-cloud connection suggests that variations in geomagnetic field intensity could change climate through modulation of CR flux. This hypothesis, however, is not well-tested using robust geological evidence. Here we present paleoclimate and paleoenvironment records of five interglacial periods that include two geomagnetic polarity reversals. Marine oxygen isotope stages 19 and 31 contain both anomalous cooling intervals during the sea-level highstands and the Matuyama-Brunhes and Lower Jaramillo reversals, respectively. This contrasts strongly with the typical interglacial climate that has the temperature maximum at the sea-level peak. The cooling occurred when the field intensity dropped to 40% increase in CR flux. The climate warmed rapidly when field intensity recovered. We suggest that geomagnetic field intensity can influence global climate through the modulation of CR flux.

  16. Growth enhancement and gene expression of Arabidopsis thaliana irradiated with active oxygen species

    Science.gov (United States)

    Watanabe, Satoshi; Ono, Reoto; Hayashi, Nobuya; Shiratani, Masaharu; Tashiro, Kosuke; Kuhara, Satoru; Inoue, Asami; Yasuda, Kaori; Hagiwara, Hiroko

    2016-07-01

    The characteristics of plant growth enhancement effect and the mechanism of the enhancement induced by plasma irradiation are investigated using various active species in plasma. Active oxygen species in oxygen plasma are effective for growth enhancement of plants. DNA microarray analysis of Arabidopsis thaliana indicates that the genes coding proteins that counter oxidative stresses by eliminating active oxygen species are expressed at significantly high levels. The size of plant cells increases owing to oxygen plasma irradiation. The increases in gene expression levels and cell size suggest that the increase in the expression level of the expansin protein is essential for plant growth enhancement phenomena.

  17. Educating Students for a Lifetime of Physical Activity: Enhancing Mindfulness, Motivation, and Meaning

    Science.gov (United States)

    Ennis, Catherine D.

    2017-01-01

    For many years, pedagogical scholars and physical education (PE) teachers have worked to enhance effective teaching and learning environments. Yet for some children, youth, and young adults, many of the benefits associated with a physically active lifestyle remain elusive. Enhancing programming and performance to meet physical activity goals may…

  18. Food constituents enhance urease activity in Healicobacter pylori.

    OpenAIRE

    Mizote, Tomoko; Inatsu, Sakiko; Ehara, Keiko

    2005-01-01

    Urease activity of Helicobacter pylori recovered from the stomach of H. pylori-infected Mongolian gerbils was affected by the diet used after infection. The effect of dietary components on urease activity was investigated by growth of H. pylori in…

  19. Turbulent Diffusion of the Geomagnetic Field and Dynamo Theories

    OpenAIRE

    Filippi, Enrico

    2016-01-01

    The thesis deals with the Dynamo Theories of the Earth’s Magnetic Field and mainly deepens the turbulence phenomena in the fluid Earth’s core. Indeed, we think that these phenomena are very important to understand the recent decay of the geomagnetic field. The thesis concerns also the dynamics of the outer core and some very rapid changes of the geomagnetic field observed in the Earth’s surface and some aspects regarding the (likely) isotropic turbulence in the Magnetohydrodynamics. These top...

  20. Evaluation of candidate geomagnetic field models for IGRF-12

    DEFF Research Database (Denmark)

    Thébault, Erwan; Finlay, Chris; Alken, Patrick

    2015-01-01

    Background: The 12th revision of the International Geomagnetic Reference Field (IGRF) was issued in December 2014 by the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group V-MOD (http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html). This revision comprises new spherical...... by the British Geological Survey (UK), DTU Space (Denmark), ISTerre (France), IZMIRAN (Russia), NOAA/NGDC (USA), GFZ Potsdam (Germany), NASA/GSFC (USA), IPGP (France), LPG Nantes (France), and ETH Zurich (Switzerland). Each candidate model was carefully evaluated and compared to all other models and a mean model...

  1. IMF sector behavior estimated from geomagnetic data at South Pole

    International Nuclear Information System (INIS)

    Matsushita, S.; Xu, W.h.

    1981-01-01

    IMF sector behavior which has previously been estimated from the geomagnetic data at Godhavn is confirmed by study of the data at South Pole for 1959--1970 with the same estimation technique, taking the difference between northern and southern hemispheres into consideration. A method to improve (about 18%) the agreement between assigned and actual sector structures by study of the data at the two stations is suggested. Geomagnetic disturbance effects on sector estimation are discussed, and reversed sector effects in winter are given special emphasis

  2. Evaluation of candidate geomagnetic field models for IGRF-12

    OpenAIRE

    Erwan Thébault; Christopher C. Finlay; Patrick Alken; Ciaran D. Beggan; Elisabeth Canet; Arnaud Chulliat; Benoit Langlais; V. Lesur; Frank J. Lowes; Chandrasekharan Manoj; Martin Rother; Reyko Schachtschneider

    2015-01-01

    Background: The 12th revision of the International Geomagnetic Reference Field (IGRF) was issued in December 2014 by the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group V-MOD (http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html). This revision comprises new spherical harmonic main field models for epochs 2010.0 (DGRF-2010) and 2015.0 (IGRF-2015) and predictive linear secular variation for the interval 2015.0-2020.0 (SV-2010-2015). Findings: The models were deri...

  3. International Geomagnetic Reference Field: the 12th generation

    OpenAIRE

    Thébault , Erwan; Finlay , Christopher ,; Beggan , Ciarán ,; Alken , Patrick; Aubert , Julien ,; Barrois , Olivier; Bertrand , François; Bondar , Tatiana; Boness , Axel; Brocco , Laura; Canet , Elisabeth ,; Chambodut , Aude; Chulliat , Arnaud ,; Coïsson , Pierdavide ,; Civet , François

    2015-01-01

    International audience; The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch 2010.0, a main field model for epoch 2015.0, and a linear annual predictive secular variation model for 2015.0-2020.0. Here, we present the equations defining the IGRF model, p...

  4. Westward ionospheric currents over the dip equator during geomagnetic disturbances

    International Nuclear Information System (INIS)

    Rastogi, R.G.

    1975-01-01

    During geomagnetic disturbed periods, the q type of sporadic E layer near the dip equator is shown to disappear with maximum error of five minutes during the period when the difference of the geomagnetic H field between the equatorial and non-equatorial station decreases below the night level. These periods are identified with the reversal to westward direction of the electrojet currents at the base of the E region around 100 km level irrespective of the changes in the S/subq/ current system which might be produced by the disturbance

  5. Focus on Freshman: Basic Instruction Programs Enhancing Physical Activity

    Science.gov (United States)

    Curry, Jarred; Jenkins, Jayne M.; Weatherford, Jennifer

    2015-01-01

    Physical activity sharply decreases after different life stages, particularly high school graduation to beginning university education. The purpose of this study was to investigate the effect of a specifically designed university physical activity class, Exercise Planning for Freshman (EPF), on students' physical activity and group cohesion…

  6. Eliminating large-scale magnetospheric current perturbations from long-term geomagnetic observatory data

    Science.gov (United States)

    Pick, L.; Korte, M. C.

    2016-12-01

    Magnetospheric currents generate the largest external contribution to the geomagnetic field observed on Earth. Of particular importance is the solar-driven effect of the ring current whose fluctuations overlap with internal field secular variation (SV). Recent core field models thus co-estimate this effect but their validity is limited to the last 15 years offering satellite data. We aim at eliminating magnetospheric modulation from the whole geomagnetic observatory record from 1840 onwards in order to obtain clean long-term SV that will enhance core flow and geodynamo studies.The ring current effect takes form of a southward directed external dipole field aligned with the geomagnetic main field axis. Commonly the Dst index (Sugiura, 1964) is used to parametrize temporal variations of this dipole term. Because of baseline instabilities, the alternative RC index was derived from hourly means of 21 stations spanning 1997-2013 (Olsen et al., 2014). We follow their methodology based on annual means from a reduced station set spanning 1960-2010. The absolute level of the variation so determined is "hidden" in the static lithospheric offsets taken as quiet-time means. We tackle this issue by subtracting crustal biases independently calculated for each observatory from an inversion of combined Swarm satellite and observatory data.Our index reproduces the original annual RC index variability with a reasonable offset of -10 nT in the reference time window 2000-2010. Prior to that it depicts a long-term trend consistent with the external dipole term from COV-OBS (Gillet et al., 2013), being the only long-term field model available for comparison. Sharper variations that are better correlated with the Ap index than the COV-OBS solution lend support to the usefulness of our initial modeling approach. Following a detailed sensitivity study of station choice future work will focus on increasing the resolution from annual to hourly means.

  7. A study of the geomagnetic indices asymmetry based on the interplanetary magnetic field polarities

    Science.gov (United States)

    El-Borie, M. A.; El-Taher, A. M.; Aly, N. E.; Bishara, A. A.

    2018-05-01

    Data of geomagnetic indices ( aa, Kp, Ap, and Dst) recorded near 1 AU over the period 1967-2016, have been studied based on the asymmetry between the interplanetary magnetic field (IMF) directions above and below of the heliospheric current sheet (HCS). Our results led to the following conclusions: (i) Throughout the considered period, 31 random years (62%) showed apparent asymmetries between Toward (T) and Away (A) polarity days and 19 years (38%) exhibited nearly a symmetrical behavior. The days of A polarity predominated over the T polarity days by 4.3% during the positive magnetic polarity epoch (1991-1999). While the days of T polarity exceeded the days of A polarity by 5.8% during the negative magnetic polarity epoch (2001-2012). (ii) Considerable yearly North-South (N-S) asymmetries of geomagnetic indices observed throughout the considered period. (iii) The largest toward dominant peaks for aa and Ap indices occurred in 1995 near to minimum of solar activity. Moreover, the most substantial away dominant peaks for aa and Ap indices occurred in 2003 (during the descending phase of the solar cycle 23) and in 1991 (near the maximum of solar activity cycle) respectively. (iv) The N-S asymmetry of Kp index indicated a most significant away dominant peak occurred in 2003. (v) Four of the away dominant peaks of Dst index occurred at the maxima of solar activity in the years 1980, 1990, 2000, and 2013. The largest toward dominant peak occurred in 1991 (at the reversal of IMF polarity). (vi) The geomagnetic indices ( aa, Ap, and Kp) all have northern dominance during positive magnetic polarity epoch (1971-1979), while the asymmetries shifts to the southern solar hemisphere during negative magnetic polarity epoch (2001-2012).

  8. Special issue “International Geomagnetic Reference Field—the twelfth generation”

    OpenAIRE

    Thébault, E.; Finlay, C. C.; Toh, H.

    2015-01-01

    This special issue of Earth, Planets and Space, synthesizes the efforts made during the construction of the twelfth generation of the International Geomagnetic Reference Field (IGRF-12) that was released online in December 2014 (http://www.ngdc.noaa.gov/IAGA/vmod/ igrf.html). The IGRF-12 is a series of standard mathematical models describing the large scale internal part of the Earth’s magnetic field between epochs 1900.0 and 2015.0 with a forecast to epoch 2020.0. This activity has been main...

  9. Enhanced Gamma Oscillatory Activity in Rats with Chronic Inflammatory Pain

    OpenAIRE

    Wang, Jing; Wang, Jing; Xing, Guo-Gang; Li, Xiaoli; Wan, You

    2016-01-01

    It has been reported that oscillatory gamma activity participates in brief acute pain and tonic ongoing pain. It is of great interest to determine whether the gamma activity is involved in chronic pain since chronic pain is a more severe pathological condition characterized by pain persistency. To investigate the oscillatory gamma activity in chronic pain, in the present study, we recorded spontaneous electrocorticogram (ECoG) signals during chronic pain development in rats with chronic infla...

  10. The Running Wheel Enhances Food Anticipatory Activity: An Exploratory Study

    OpenAIRE

    Flôres, Danilo E. F. L.; Bettilyon, Crystal N.; Jia, Lori; Yamazaki, Shin

    2016-01-01

    Rodents anticipate rewarding stimuli such as daily meals, mates, and stimulant drugs. When a single meal is provided daily at a fixed time of day, an increase in activity, known as food anticipatory activity (FAA), occurs several hours before feeding time. The factors affecting the expression of FAA have not been well-studied. Understanding these factors may provide clues to the undiscovered anatomical substrates of food entrainment. In this study we determined whether wheel-running activity,...

  11. Enhanced activation of periodate by iodine-doped granular activated carbon for organic contaminant degradation.

    Science.gov (United States)

    Li, Xiaowan; Liu, Xitao; Lin, Chunye; Qi, Chengdu; Zhang, Huijuan; Ma, Jun

    2017-08-01

    In this study, iodine-doped granular activated carbon (I-GAC) was prepared and subsequently applied to activate periodate (IO 4 - ) to degrade organic contaminants at ambient temperature. The physicochemical properties of GAC and I-GAC were examined using scanning electron microscopy, N 2 adsorption/desorption, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. No significant difference was observed between the two except for the existence of triiodide (I 3 - ) and pentaiodide (I 5 - ) on I-GAC. The catalytic activity of I-GAC towards IO 4 - was evaluated by the degradation of acid orange 7 (AO7), and superior catalytic performance was achieved compared with GAC. The effects of some influential parameters (preparation conditions, initial solution pH, and coexisting anions) on the catalytic ability were also investigated. Based on radical scavenging experiments, it appeared that IO 3 was the predominant reactive species in the I-GAC/IO 4 - system. The mechanism underlying the enhanced catalytic performance of I-GAC could be explained by the introduction of negatively charged I 3 - and I 5 - into I-GAC, which induced positive charge density on the surface of I-GAC. This accelerated the interaction between I-GAC and IO 4 - , and subsequently mediated the increasing generation of iodyl radicals (IO 3 ). Furthermore, a possible degradation pathway of AO7 was proposed according to the intermediate products identified by gas chromatography-mass spectrometry. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Surface electric fields and geomagnetically induced currents in the Scottish Power grid during the 30 October 2003 geomagnetic storm

    OpenAIRE

    Thomson, Alan W.P.; McKay, Allan J.; Clarke, Ellen; Reay, Sarah J.

    2005-01-01

    A surface electric field model is used to estimate the UK surface E field during the 30 October 2003 severe geomagnetic storm. This model is coupled with a power grid model to determine the flow of geomagnetically induced currents (GIC) through the Scottish part of the UK grid. Model data are compared with GIC measurements at four sites in the power network. During this storm, measured and modeled GIC levels exceeded 40 A, and the surface electric field reached 5 V/km at sites in ...

  13. Active and Inactive Enhancers Cooperate to Exert Localized and Long-Range Control of Gene Regulation.

    Science.gov (United States)

    Proudhon, Charlotte; Snetkova, Valentina; Raviram, Ramya; Lobry, Camille; Badri, Sana; Jiang, Tingting; Hao, Bingtao; Trimarchi, Thomas; Kluger, Yuval; Aifantis, Iannis; Bonneau, Richard; Skok, Jane A

    2016-06-07

    V(D)J recombination relies on the presence of proximal enhancers that activate the antigen receptor (AgR) loci in a lineage- and stage-specific manner. Unexpectedly, we find that both active and inactive AgR enhancers cooperate to disseminate their effects in a localized and long-range manner. Here, we demonstrate the importance of short-range contacts between active enhancers that constitute an Igk super-enhancer in B cells. Deletion of one element reduces the interaction frequency between other enhancers in the hub, which compromises the transcriptional output of each component. Furthermore, we establish that, in T cells, long-range contact and cooperation between the inactive Igk enhancer MiEκ and the active Tcrb enhancer Eβ alters enrichment of CBFβ binding in a manner that impacts Tcrb recombination. These findings underline the complexities of enhancer regulation and point to a role for localized and long-range enhancer-sharing between active and inactive elements in lineage- and stage-specific control. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  14. Active and Inactive Enhancers Cooperate to Exert Localized and Long-Range Control of Gene Regulation

    Directory of Open Access Journals (Sweden)

    Charlotte Proudhon

    2016-06-01

    Full Text Available V(DJ recombination relies on the presence of proximal enhancers that activate the antigen receptor (AgR loci in a lineage- and stage-specific manner. Unexpectedly, we find that both active and inactive AgR enhancers cooperate to disseminate their effects in a localized and long-range manner. Here, we demonstrate the importance of short-range contacts between active enhancers that constitute an Igk super-enhancer in B cells. Deletion of one element reduces the interaction frequency between other enhancers in the hub, which compromises the transcriptional output of each component. Furthermore, we establish that, in T cells, long-range contact and cooperation between the inactive Igk enhancer MiEκ and the active Tcrb enhancer Eβ alters enrichment of CBFβ binding in a manner that impacts Tcrb recombination. These findings underline the complexities of enhancer regulation and point to a role for localized and long-range enhancer-sharing between active and inactive elements in lineage- and stage-specific control.

  15. Allosteric activation of midazolam CYP3A5 hydroxylase activity by icotinib - Enhancement by ketoconazole.

    Science.gov (United States)

    Zhuang, XiaoMei; Zhang, TianHong; Yue, SiJia; Wang, Juan; Luo, Huan; Zhang, YunXia; Li, Zheng; Che, JinJing; Yang, HaiYing; Li, Hua; Zhu, MingShe; Lu, Chuang

    2016-12-01

    Icotinib (ICO), a novel small molecule and a tyrosine kinase inhibitor, was developed and approved recently in China for non-small cell lung cancer. During screening for CYP inhibition potential in human liver microsomes (HLM), heterotropic activation toward CYP3A5 was revealed. Activation by icotinib was observed with CYP3A-mediated midazolam hydroxylase activity in HLM (∼40% over the baseline) or recombinant human CYP3A5 (rhCYP3A5) (∼70% over the baseline), but not in the other major CYPs including rhCYP3A4. When co-incubated with selective CYP3A4 inhibitor CYP3cide or monoclonal human CYP3A4 inhibitory antibody in HLM, the activation was extended to ∼60%, suggesting CYP3A5 might be the isozyme involved. Further, the relative activation was enhanced to ∼270% in rhCYP3A5 in the presence of ketoconazole. The activation was substrate and pathway dependent and observed only in the formation of 1'-OH-midazolam, and not 4-OH-midazolam, 6β-OH-testosterone, or oxidized nifedipine. The activation requires the presence of cytochrome b5 and it is only observed in the liver microsomes of dogs, monkeys, and humans, but not in rats and mice. Kinetic analyses of 1'-OH-midazolam formation showed that ICO increased the V max values in HLM and rhCYP3A5 with no significant changes in K m values. By adding CYP3cide with ICO to the incubation, the V max values increased 2-fold over the CYP3cide control. Addition of ketoconazole with ICO alone or ICO plus CYP3cide resulted in an increase in V max values and decrease in K m values compared to their controls. This phenomenon may be attributed to a new mechanism of CYP3A5 heterotropic activation, which warrants further investigation. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Diagnosing low earth orbit satellite anomalies using NOAA-15 electron data associated with geomagnetic perturbations

    Science.gov (United States)

    Ahmad, Nizam; Herdiwijaya, Dhani; Djamaluddin, Thomas; Usui, Hideyuki; Miyake, Yohei

    2018-05-01

    A satellite placed in space is constantly affected by the space environment, resulting in various impacts from temporary faults to permanent failures depending on factors such as satellite orbit, solar and geomagnetic activities, satellite local time, and satellite construction material. Anomaly events commonly occur during periods of high geomagnetic activity that also trigger plasma variation in the low Earth orbit (LEO) environment. In this study, we diagnosed anomalies in LEO satellites using electron data from the Medium Energy Proton and Electron Detector onboard the National Oceanic and Atmospheric Administration (NOAA)-15 satellite. In addition, we analyzed the fluctuation of electron flux in association with geomagnetic disturbances 3 days before and after the anomaly day. We selected 20 LEO anomaly cases registered in the Satellite News Digest database for the years 2000-2008. Satellite local time, an important parameter for anomaly diagnosis, was determined using propagated two-line element data in the SGP4 simplified general perturbation model to calculate the longitude of the ascending node of the satellite through the position and velocity vectors. The results showed that the majority of LEO satellite anomalies are linked to low-energy electron fluxes of 30-100 keV and magnetic perturbations that had a higher correlation coefficient ( 90%) on the day of the anomaly. The mean local time calculation for the anomaly day with respect to the nighttime migration of energetic electrons revealed that the majority of anomalies (65%) occurred on the night side of Earth during the dusk-to-dawn sector of magnetic local time.

  17. Short Communication : Enhancing the Quality and Activity of ...

    African Journals Online (AJOL)

    Effects of application of benzoic acid, sodium benzoate and sodium metabisulfite, prior to sun drying of papaya latex, on enzymic activity, colour appearance and smell of the crude papain produced were investigated. The preservatives improved appearance/colour, smell and enzymic activity with respect to control sample ...

  18. Enhancing Learning Outcomes through Application Driven Activities in Marketing

    Science.gov (United States)

    Stegemann, Nicole; Sutton-Brady, Catherine

    2013-01-01

    This paper introduces an activity used in class to allow students to apply previously acquired information to a hands-on task. As the authors have previously shown active learning is a way to effectively facilitate and improve students' learning outcomes. As a result to improve learning outcomes we have overtime developed a series of learning…

  19. Marine sediments and Beryllium-10 record of the geomagnetic moment variations during the Brunhes period.

    Science.gov (United States)

    Ménabréaz, Lucie; Thouveny, Nicolas; Bourlès, Didier; Demory, François

    2010-05-01

    Over millennial time scales, the atmospheric production of the cosmonuclid 10Be (half-life 1.387 ± 0.012 Ma [Shmeleff et al., 2009; Korschinek et al., 2009]) is modulated by the geomagnetic field strength, following a negative power law (e.g. Lal, 1988; Masarik and Beer, 2009). With respect to paleomagnetic reconstructions, 10Be-derived paleointensity records can therefore constitute an alternative, global and independent reading of the dipole moment variations. During the last years, efforts have been made to extract a geomagnetic signal from single and stacked 10Be records in natural archives such as ice and marine sediments (e.g. Carcaillet et al., 2004; Christl et al., 2007; Muscheler et al., 2005). In marine sediments, the 10Be concentration results from complex interplay of several processes: cosmogenic production, adsorption on sediment particles, redistribution by fluviatile and oceanic transport, and deposition. Therefore, a correction procedure is required to consider both sediment redistribution and enhanced scavenging, which can alter the primary signatures. To reconstruct the succession of field intensity lows accompanying excursions during the Brunhes chron, we investigated authigenic 10Be/9Be record of marine sequences also studied for paleomagnetism and oxygen isotopes. Mid and low latitude sites were preferred in order to benefit from the most efficient modulation by the magnetospheric shielding. We present a high resolution authigenic 10Be/9Be record of the last 50 ka recovered from the Portuguese Margin, that deciphers the cosmonuclide 10Be overproduction created by the geomagnetic dipole low associated with the Laschamp excursion. This record is compared to other proxy records of the geomagnetic field variations for the same time interval: (1) the relative paleointensity (RPI) reconstructed from the same sediments and the GLOPIS-75 record (Laj et al., 2004), (2) the absolute VDM record based on absolute paleointensities measured on lava flows

  20. An investication into geomagnetic and atmospheric response ...

    African Journals Online (AJOL)

    ... Magadan, Khabarovsk, Wakkanai, Akita, Kokubunji, Okinawa and Manila. The study shows that the present storm is double step, and the leading single magnetospheric process that was responsible for both the first and second Dst decrease is the enhancement of the plasma sheet. An enhanced solar wind density drove, ...

  1. Enhancement of antimicrobial activity of chitosan by irradiation

    International Nuclear Information System (INIS)

    Matsuhashi, S.; Kume, T.

    1997-01-01

    Antimicrobial activity of irradiated chitosan was studied against Escherichia coli B/r. Irradiation of chitosan at 100 kGy under dry conditions was effective in increasing the activity, and inhibited the growth of E. coli completely. The molecular weight of chitosan significantly decreased with the increase in irradiation dose, whereas the relative surface charge of chitosan was decreased only 3% by 100 kGy irradiation. Antimicrobial activity assay of chitosan fractionated according to molecular weight showed that 1 x 10 5 -3 x 10 5 fraction was most effective in suppressing the growth of E coli. This fraction comprised only 8% of the 100 kGy irradiated chitosan. On the other hand, chitosan whose molecular weight was less than 1 x 10 5 had no activity. The results show that low dose irradiation, specifically 100 kGy, of chitosan gives enough degradation to increase its antimicrobial activity as a result of a change in molecular weight. (Author)

  2. GPS phase scintillation at high latitudes during the geomagnetic storm of 17-18 March 2015

    DEFF Research Database (Denmark)

    Prikryl, P.; Ghoddousi-Fard, R.; Weygand, J. M.

    2016-01-01

    The geomagnetic storm of 17–18 March 2015 was caused by the impacts of a coronal mass ejection and a high-speed plasma stream from a coronal hole. The high-latitude ionosphere dynamics is studied using arrays of ground-based instruments including GPS receivers, HF radars, ionosondes, riometers......, and magnetometers. The phase scintillation index is computed for signals sampled at a rate of up to 100 Hz by specialized GPS scintillation receivers supplemented by the phase scintillation proxy index obtained from geodetic-quality GPS data sampled at 1 Hz. In the context of solar wind coupling...... to the magnetosphere-ionosphere system, it is shown that GPS phase scintillation is primarily enhanced in the cusp, the tongue of ionization that is broken into patches drawn into the polar cap from the dayside storm-enhanced plasma density, and in the auroral oval. In this paper we examine the relation between...

  3. High salt intake enhances swim stress-induced PVN vasopressin cell activation and active stress coping.

    Science.gov (United States)

    Mitchell, N C; Gilman, T L; Daws, L C; Toney, G M

    2018-07-01

    Stress contributes to many psychiatric disorders; however, responsivity to stressors can vary depending on previous or current stress exposure. Relatively innocuous heterotypic (differing in type) stressors can summate to result in exaggerated neuronal and behavioral responses. Here we investigated the ability of prior high dietary sodium chloride (salt) intake, a dehydrating osmotic stressor, to enhance neuronal and behavioral responses of mice to an acute psychogenic swim stress (SS). Further, we evaluated the contribution of the osmo-regulatory stress-related neuropeptide arginine vasopressin (VP) in the hypothalamic paraventricular nucleus (PVN), one of only a few brain regions that synthesize VP. The purpose of this study was to determine the impact of high dietary salt intake on responsivity to heterotypic stress and the potential contribution of VPergic-mediated neuronal activity on high salt-induced stress modulation, thereby providing insight into how dietary (homeostatic) and environmental (psychogenic) stressors might interact to facilitate psychiatric disorder vulnerability. Salt loading (SL) with 4% saline for 7 days was used to dehydrate and osmotically stress mice prior to exposure to an acute SS. Fluid intake and hematological measurements were taken to quantify osmotic dehydration, and serum corticosterone levels were measured to index stress axis activation. Immunohistochemistry (IHC) was used to stain for the immediate early gene product c-Fos to quantify effects of SL on SS-induced activation of neurons in the PVN and extended amygdala - brain regions that are synaptically connected and implicated in responding to osmotic stress and in modulation of SS behavior, respectively. Lastly, the role of VPergic PVN neurons and VP type 1 receptor (V1R) activity in the amygdala in mediating effects of SL on SS behavior was evaluated by quantifying c-Fos activation of VPergic PVN neurons and, in functional experiments, by nano-injecting the V1R selective

  4. Low dose radiation enhances the Locomotor activity of D. melanogaster

    Energy Technology Data Exchange (ETDEWEB)

    Seong, Ki Moon; Lee, Buyng Sub; Nam Seon Young; Kim, Ji Young; Yang, Kwang Hee; Choi, Tae In; Kim, Cha Soon [Radiation Effect Research Team, Radiation Health Research Institute, Korea Hydro and Nuclear Power Co., Ltd., Gyeongju (Korea, Republic of)

    2013-04-15

    Mild stresses at low level including radiation can induce the beneficial effects in many vertebrate and invertebrate species. However, a large amount of studies in radiation biology have focused on the detrimental effects of high dose radiation (HDR) such as the increased incidence of cancers and developmental diseases. Low dose radiation (LDR) induces biologically favorable effects in diverse fields, for example, cancer development, genomic instability, immune response, and longevity. Our previous data indicated that LDR promotes cells proliferation of which degree is not much but significant, and microarray data explained that LDR irradiated fruit flies showing the augmented immunity significantly changed the program for gene expression of many genes in Gene Ontology (GO) categories related to metabolic process. Metabolic process in development one of major contributors in organism growth, interbreeding, motility, and aging. Therefore, it is valuable to examine whether LDR change the physiological parameters related to metabolism, and how LDR regulates the metabolism in D. melanogaster. In this study, to investigate that LDR influences change of the metabolism, a representative parameter, locomotor activity. In addition, the activation of several cellular signal molecules was determined to investigate the specific molecular mechanism of LDR effects on the metabolism. We explored whether ionizing radiation affects the motility activity. We performed the RING assays to evaluate the locomotor activity, a representative parameter presenting motility of fruit flies. HDR dramatically decreased the motor activity of irradiated flies. Surprisingly, the irradiated flies at low dose radiation in both acute and chronic showed the significantly increased locomotor activity, compared to non-irradiated flies. Irradiation would induce change of the several signal pathways for flies to respond to it. The activation of some proteins involved in the cells proliferation and stress

  5. Protection of power transformers against geomagnetically induced currents

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2011-01-01

    Full Text Available The article examines the problem of saturation and failure of power transformers under geomagnetically induced currents and currents of the E3 component of high-altitude nuclear explosions. It also describes a special protective relay reacting on DC component in the transformer neutral current.

  6. Geomagnetic matching navigation algorithm based on robust estimation

    Science.gov (United States)

    Xie, Weinan; Huang, Liping; Qu, Zhenshen; Wang, Zhenhuan

    2017-08-01

    The outliers in the geomagnetic survey data seriously affect the precision of the geomagnetic matching navigation and badly disrupt its reliability. A novel algorithm which can eliminate the outliers influence is investigated in this paper. First, the weight function is designed and its principle of the robust estimation is introduced. By combining the relation equation between the matching trajectory and the reference trajectory with the Taylor series expansion for geomagnetic information, a mathematical expression of the longitude, latitude and heading errors is acquired. The robust target function is obtained by the weight function and the mathematical expression. Then the geomagnetic matching problem is converted to the solutions of nonlinear equations. Finally, Newton iteration is applied to implement the novel algorithm. Simulation results show that the matching error of the novel algorithm is decreased to 7.75% compared to the conventional mean square difference (MSD) algorithm, and is decreased to 18.39% to the conventional iterative contour matching algorithm when the outlier is 40nT. Meanwhile, the position error of the novel algorithm is 0.017° while the other two algorithms fail to match when the outlier is 400nT.

  7. Methodology for simulation of geomagnetically induced currents in power systems

    Directory of Open Access Journals (Sweden)

    Boteler David

    2014-07-01

    Full Text Available To assess the geomagnetic hazard to power systems it is useful to be able to simulate the geomagnetically induced currents (GIC that are produced during major geomagnetic disturbances. This paper examines the methodology used in power system analysis and shows how it can be applied to modelling GIC. Electric fields in the area of the power network are used to determine the voltage sources or equivalent current sources in the transmission lines. The power network can be described by a mesh impedance matrix which is combined with the voltage sources to calculate the GIC in each loop. Alternatively the power network can be described by a nodal admittance matrix which is combined with the sum of current sources into each node to calculate the nodal voltages which are then used to calculate the GIC in the transmission lines and GIC flowing to ground at each substation. Practical calculations can be made by superposition of results calculated separately for northward and eastward electric fields. This can be done using magnetic data from a single observatory to calculate an electric field that is a uniform approximation of the field over the area of the power system. It is also shown how the superposition of results can be extended to use data from two observatories: approximating the electric field by a linear variation between the two observatory locations. These calculations provide an efficient method for simulating the GIC that would be produced by historically significant geomagnetic storm events.

  8. Evidence for a new geomagnetic jerk in 2014

    DEFF Research Database (Denmark)

    Torta, J. Miquel; Pavón-Carrasco, Francisco Javier; Marsal, Santiago

    2015-01-01

    The production of quasi-definitive data at Ebre observatory has enabled us to detect a new geomagnetic jerk in early 2014. This has been confirmed by analyzing data at several observatories in the European-African and Western Pacific-Australian sectors in the classical fashion of looking for the ...

  9. Long-term trends in geomagnetic and climatic variability

    Czech Academy of Sciences Publication Activity Database

    Bucha, Václav

    2002-01-01

    Roč. 27, 6/7 (2002), s. 427-731 ISSN 1474-7065 R&D Projects: GA AV ČR IAA3012806 Institutional research plan: CEZ:AV0Z3012916 Keywords : geomagnetic forcing * climatic variability * global warming Subject RIV: DE - Earth Magnetism, Geodesy, Geography

  10. Surface electric fields for North America during historical geomagnetic storms

    Science.gov (United States)

    Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.

    2013-01-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  11. Geomagnetic core field models in the satellite era

    DEFF Research Database (Denmark)

    Lesur, Vincent; Olsen, Nils; Thomson, Alan W. P.

    2011-01-01

    After a brief review of the theoretical basis and difficulties that modelers are facing, we present three recent models of the geomagnetic field originating in the Earth’s core. All three modeling approaches are using recent observatory and near-Earth orbiting survey satellite data. In each case...

  12. Eruptive prominences and long-delay geomagnetic storms

    International Nuclear Information System (INIS)

    Wright, C.S.

    1983-01-01

    The relationship between disappearing solar fragments and geomagnetic disturbances was investigated. It is shown that long-delay storms are associated with filaments well removed from the disc centre, and particularly in the case of large filaments and prominences, the proportion of events that produce long-delay storms increases with angular distance from the centre

  13. Effects of geomagnetic storms on the bottomside ionospheric F region

    Czech Academy of Sciences Publication Activity Database

    Burešová, Dalia

    2005-01-01

    Roč. 35, - (2005), s. 429-439 ISSN 0273-1177 R&D Projects: GA AV ČR(CZ) IAA3042102 Institutional research plan: CEZ:AV0Z30420517 Keywords : Ionosphere * Geomagnetic storm * Bottomside F region electron density Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.706, year: 2005

  14. Statistical Relationship between Sawtooth Oscillations and Geomagnetic Storms

    Directory of Open Access Journals (Sweden)

    Jae-Hun Kim

    2008-06-01

    Full Text Available We have investigated a statistical relationship between sawtooth oscillations and geomagnetic storms during 2000-2004. First of all we selected a total of 154 geomagnetic storms based on the Dst index, and distinguished between different drivers such as Coronal Mass Ejection (CME and Co-rotating Interaction Region (CIR. Also, we identified a total of 48 sawtooth oscillation events based on geosynchronous energetic particle data for the same 2000-2004 period. We found that out of the 154 storms identified, 47 storms indicated the presence of sawtooth oscillations. Also, all but one sawtooth event identified occurred during a geomagnetic storm interval. It was also found that sawtooth oscillation events occur more frequently for storms driven by CME (˜62% than for storms driven by CIR (˜30%. In addition, sawtooth oscillations occurred mainly (˜82% in the main phase of storms for CME-driven storms while they occurred mostly (˜78% during the storm recovery phase for CIR-driven storms. Next we have examined the average characteristics of the Bz component of IMF, and solar wind speed, which were the main components for driving geomagnetic storm. We found that for most of the sawtooth events, the IMF Bz corresponds to --15 to 0 nT and the solar wind speed was in the range of 400˜700 km/s. We found that there was a weak tendency that the number of teeth for a given sawtooth event interval was proportional to the southward IMF Bz magnitude.

  15. Transport from chaotic orbits in the geomagnetic tail

    International Nuclear Information System (INIS)

    Horton, W.; Tajima, T.

    1991-01-01

    The rapid change in direction and magnitude of the magnetic field vector in crossing the quasineutral sheet in the geomagnetic tail leads to deterministic Hamiltonian chaos. The finite correlation times in the single particle orbits due to the continuum of orbital frequencies leads to well-defined collisionless transport coefficients. The transport coefficients are derived for plasma trapped in the quasineutral sheet

  16. Reduced graphene oxide wrapped Ag nanostructures for enhanced SERS activity

    Science.gov (United States)

    Nair, Anju K.; Kala, M. S.; Thomas, Sabu; Kalarikkal, Nandakumar

    2018-04-01

    Graphene - metal nanoparticle hybrids have received great attention due to their unique electronic properties, large specific surface area, very high conductivity and more charge transfer. Thus, it is extremely advantages to develop a simple and efficient process to disperse metal nanostructures over the surface of graphene sheets. Herein, we report a hydrothermal assisted strategy for developing reduced graphene oxide /Ag nanomorphotypes (cube, wire) for surface enhanced Raman scattering (SERS) applications, considering the advantages of synergistic effect of graphene and plasmonic properties of Ag nanomorphotypes.

  17. Thermospheric response observed over Fritz peak, Colorado, during two large geomagnetic storms near solar cycle maximum

    International Nuclear Information System (INIS)

    Hernandez, G.; Roble, R.G.; Ridley, E.C.; Allen, J.H.

    1982-01-01

    Nightime thermospheric winds and temperatures have been measured over Fritz Peak Observatory, Colorado (39.9 0 N, 105.5 0 W), with a high resolution Fabry-Perot spectrometer. The winds and temperatures are obtained from the Doppler shifts and line profiles of the (O 1) 15,867K (630 nm) line emission. Measurements made during two large geomagnetic storm periods near solar cycle maximum reveal a thermospheric response to the heat and momentum sources associated with these storms that is more complex than the ones measured near solar cycle minimum. In the earlier measurements made during solar cycle minimum, the winds to the north of Fritz Peak Observatory had an enhanced equatorward component and the winds to the south were also equatorward, usually with smaller velocities. The winds measured to the east and west of the observatory both had an enhanced westward wind component. For the two large storms near the present solar cycle maximum period converging winds are observed in each of the cardinal directions from Fritz Peak Observatory. These converging winds with speeds of hundreds of meters per second last for several hours. The measured neutral gas temperature in each of the directions also increases several hundred degrees Kelvin. Numerical experiments done with the NCAR thermospheric general circulation model (TGCM) suggest that the winds to the east and north of the station are driven by high-latitude heating and enhanced westward ion drag associated with magnetospheric convection. The cause of the enhanced poleward and eastward winds measured to the south and west of Fritz Peak Observatory, respectively, is not known. During geomagnetic quiet conditions the circulation is typically from the soutwest toward the northeast in the evening hours

  18. Sustainable Regeneration of Nanoparticle Enhanced Activated Carbon in Water

    Science.gov (United States)

    The regeneration and reuse of exhausted granular activated carbon (GAC) is an appropriate method for lowering operational and environmental costs. Advanced oxidation is a promising environmental friendly technique for GAC regeneration. The main objective of this research was to ...

  19. Enhanced Photocatalytic Activity of Vacuum-activated TiO2 Induced by Oxygen Vacancies.

    Science.gov (United States)

    Dong, Guoyan; Wang, Xin; Chen, Zhiwu; Lu, Zhenya

    2018-05-01

    TiO 2 (Degussa P25) photocatalysts harboring abundant oxygen vacancies (Vacuum P25) were manufactured using a simple and economic Vacuum deoxidation process. Control experiments showed that temperature and time of vacuum deoxidation had a significant effect on Vacuum P25 photocatalytic activity. After 240 min of visible light illumination, the optimal Vacuum P25 photocatalysts (vacuum deoxidation treated at 330 °C for 3 h) reach as high as 94% and 88% of photodegradation efficiency for rhodamine B (RhB) and tetracycline, respectively, which are around 4.5 and 4.9 times as that of pristine P25. The XPS, PL and EPR analyses indicated that the oxygen vacancies were produced in the Vacuum P25 during the vacuum deoxidation process. The oxygen vacancy states can produce vacancy energy level located below the conduction band minimum, which resulting in the bandgap narrowing, thus extending the photoresponse wavelength range of Vacuum P25. The positron annihilation analysis indicated that the concentrations ratio of bulk and surface oxygen vacancies could be adjusted by changing the vacuum deoxidation temperature and time. Decreasing the ratio of bulk and surface oxygen vacancies was shown to improve photogenerated electron-hole pair separation efficiency, which leads to an obvious enhancement of the visible photocatalytic activities of Vacuum P25. © 2017 The American Society of Photobiology.

  20. Slow self-activation enhances the potency of viridin prodrugs.

    Science.gov (United States)

    Blois, Joseph; Yuan, Hushan; Smith, Adam; Pacold, Michael E; Weissleder, Ralph; Cantley, Lewis C; Josephson, Lee

    2008-08-14

    When the viridin wortmannin (Wm) is modified by reaction with certain nucleophiles at the C20 position, the compounds obtained exhibit an improved antiproliferative activity even though a covalent reaction between C20 and a lysine in the active site of PI3 kinase is essential to Wm's ability to inhibit this enzyme. Here we show that this improved potency results from an intramolecular attack by the C6 hydroxyl group that slowly converts these inactive prodrugs to the active species Wm over the 48 h duration of the antiproliferative assay. Our results provide a guide for selecting Wm-like compounds to maximize kinase inhibition with the variety of protocols used to assess the role of PI3 kinase in biological systems, or for achieving optimal therapeutic effects in vivo . In addition, the slow self-activation of WmC20 derivatives provides a mechanism that can be exploited to obtain kinase inhibitors endowed with physical and pharmacokinetic properties far different from man-made kinase inhibitors because they do not bind to kinase active sites.

  1. PROPAGATION OF THE 2014 JANUARY 7 CME AND RESULTING GEOMAGNETIC NON-EVENT

    Energy Technology Data Exchange (ETDEWEB)

    Mays, M. L.; Collinson, G.; Taktakishvili, A. [Catholic University of America, Washington, DC (United States); Thompson, B. J.; Jian, L. K.; Savani, N. P.; MacNeice, P. J.; Zheng, Y. [Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD (United States); Colaninno, R. C. [Space Science Division, Naval Research Laboratory, Washington, DC (United States); Odstrcil, D. [IGAM-Kanzelhöhe Observatory, Institute of Physics, University of Graz, Graz (Austria); Möstl, C. [George Mason University, Fairfax, VA (United States); Temmer, M., E-mail: m.leila.mays@nasa.gov [Space Research Institute, Austrian Academy of Sciences, Graz (Austria)

    2015-10-20

    On 2014 January 7 an X1.2 flare and coronal mass ejection (CME) with a radial speed ≈2500 km s{sup −1} was observed from near an active region close to disk center. This led many forecasters to estimate a rapid arrival at Earth (≈36 hr) and predict a strong geomagnetic storm. However, only a glancing CME arrival was observed at Earth with a transit time of ≈49 hr and a K{sub P} geomagnetic index of only 3−. We study the interplanetary propagation of this CME using the ensemble Wang-Sheeley-Arge (WSA)–ENLIL+Cone model, that allows a sampling of CME parameter uncertainties. We explore a series of simulations to isolate the effects of the background solar wind solution, CME shape, tilt, location, size, and speed, and the results are compared with observed in situ arrivals at Venus, Earth, and Mars. Our results show that a tilted ellipsoid CME shape improves the initial real-time prediction to better reflect the observed in situ signatures and the geomagnetic storm strength. CME parameters from the Graduated Cylindrical Shell model used as input to WSA–ENLIL+Cone, along with a tilted ellipsoid cloud shape, improve the arrival-time error by 14.5, 18.7, 23.4 hr for Venus, Earth, and Mars respectively. These results highlight that CME orientation and directionality with respect to observatories play an important role in understanding the propagation of this CME, and for forecasting other glancing CME arrivals. This study also demonstrates the importance of three-dimensional CME fitting made possible by multiple viewpoint imaging.

  2. Coronal mass ejection and stream interaction region characteristics and their potential geomagnetic effectiveness

    International Nuclear Information System (INIS)

    Lindsay, G.M.; Russell, C.T.; Luhmann, J.G.

    1995-01-01

    Previous studies have indicated that the largest geomagnetic storms are caused by extraordinary increases in the solar wind velocity and/or southward interplanetary magnetic field (IMF) produced by coronal mass ejections (CMEs) and their associated interplanetary shocks. However, much more frequent small to moderate increases in solar wind velocity and compressions in the IMF can be caused by either coronal mass ejections or fast/slow stream interactions. This study examines the relative statistics of the magnitudes of disturbances associated with the passage of both interplanetary coronal mass ejections and stream interaction regions, using an exceptionally continuous interplanetary database from the Pioneer Venus Orbiter at 0.7 AU throughout most of solar cycle 21. It is found that both stream interaction and CMEs produce magnetic fields significantly larger than the nominal IMF. Increases in field magnitude that are up to 2 and 3 times higher than the ambient field are observed for stream interaction regions and CMEs, respectively. Both stream interactions and CMEs produce large positive and negative Β z components at 0.7 AU, but only CMEs produce Β z magnitudes greater than 35 nT. CMEs are often associated with sustained periods of positive or negative Β z whereas stream interaction regions are more often associated with fluctuating Β z . CMEs tend to produce larger solar wind electric fields than stream interactions. Yet stream interactions tend to produce larger dynamic pressures than CMEs. Dst predictions based on solar wind duskward electric field and dynamic pressure indicate that CMEs produce the largest geomagnetic disturbances while the low-speed portion of stream interaction regions are least geomagnetically effective. Both stream interaction regions and CMEs contribute to low and moderate levels of activity with relative importance determined by their solar-cycle-dependent occurrence rates

  3. Business oriented educational experiments enhance active learning by engineering students

    DEFF Research Database (Denmark)

    Christiansen, Nynne Mia; Schjær-Jacobsen, Hans; Simon, Jens

    2012-01-01

    It is generally agreed that one of the keys to recreating industrial growth after the financial crisis is to mobilize universities and engineering schools to be more actively involved in innovation and entrepreneurship activities in cooperation with industrial companies. This active learning...... exploration symposium on bridging the gap between engineering education and business is proposed on the basis of the Copenhagen University College of Engineering (IHK) being involved in a DKK 50m ongoing project “Business Oriented Educational Experiments” financed by the Capital Region of Denmark...... and the European Social Fund. The project is carried out with other major educational institutions in the Copenhagen area and organized in five themes: 1) world class competences, 2) new interactions between education and business, 3) the experimenting organization, 4) education on demand, and 5) new career paths...

  4. Modification of polymer surfaces to enhance enzyme activity and stability

    DEFF Research Database (Denmark)

    Hoffmann, Christian

    Enzyme immobilization is an important concept for the development of improved biocatalytic processes, primarily through facilitated separation procedures. However, enzyme immobilization usually comes at a price of reduced biocatalytic activity. For this reason, different immobilization methods have...... already been developed, combining the same goal to improve enzyme activity, stability and selectivity. Polymer materials have shown, due to their easy processibility and versatile properties, high potential as enzyme support. However, in order to achieve improved enzyme performance, the combination...... on their tailored surface modification in order to obtain improved enzyme-support systems. Firstly, an off-stoichiometric thiol-ene (OSTE) thermosetting material was used for the development of a screening platform allowing the investigation of micro-environmental effects and their impact on the activity...

  5. Protein kinase A activation enhances β-catenin transcriptional activity through nuclear localization to PML bodies.

    Directory of Open Access Journals (Sweden)

    Mei Zhang

    Full Text Available The Protein Kinase A (PKA and Wnt signaling cascades are fundamental pathways involved in cellular development and maintenance. In the osteoblast lineage, these pathways have been demonstrated functionally to be essential for the production of mineralized bone. Evidence for PKA-Wnt crosstalk has been reported both during tumorigenesis and during organogenesis, and the nature of the interaction is thought to rely on tissue and cell context. In this manuscript, we analyzed bone tumors arising from mice with activated PKA caused by mutation of the PKA regulatory subunit Prkar1a. In primary cells from these tumors, we observed relocalization of β-catenin to intranuclear punctuate structures, which were identified as PML bodies. Cellular redistribution of β-catenin could be recapitulated by pharmacologic activation of PKA. Using 3T3-E1 pre-osteoblasts as a model system, we found that PKA phosphorylation sites on β-catenin were required for nuclear re-localization. Further, β-catenin's transport to the nucleus was accompanied by an increase in canonical Wnt-dependent transcription, which also required the PKA sites. PKA-Wnt crosstalk in the cells was bi-directional, including enhanced interactions between β-catenin and the cAMP-responsive element binding protein (CREB and transcriptional crosstalk between the Wnt and PKA signaling pathways. Increases in canonical Wnt/β-catenin signaling were associated with a decrease in the activity of the non-canonical Wnt/Ror2 pathway, which has been shown to antagonize canonical Wnt signaling. Taken together, this study provides a new understanding of the complex regulation of the subcellular distribution of β-catenin and its differential protein-protein interaction that can be modulated by PKA signaling.

  6. Enhanced activities of organically bound tritium in biota samples.

    Science.gov (United States)

    Svetlik, I; Fejgl, M; Malátová, I; Tomaskova, L

    2014-11-01

    A pilot study aimed on possible occurrence of elevated activity of non-exchangable organically bound tritium (NE-OBT) in biota was performed. The first results showed a significant surplus of NE-OBT activity in biota of the valley of Mohelno reservoir and Jihlava river. The liquid releases of HTO from the nuclear power plant Dukovany is the source of tritium in this area. This area can be a source of various types of natural samples for future studies of tritium pathways. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Variability Analysis of the Horizontal Geomagnetic Component: A Case Study Based on Records from Vassouras Observatory (Brazil)

    Science.gov (United States)

    Klausner, Virginia; Papa, Andres; Mendes, Odim; Oliveira Domingues, Margarete

    It is well known that any of the components of the magnetic field measured on the Earth's surface presents characteristic frequencies with 24, 12, 8 and 6-hour period. Those typical kinds of oscillations of the geomagnetic field are known as solar quiet variation and are primary due to the global thermotidal wind systems which conduct currents flowing in the "dynamo region" of the ionosphere, the E-region. In this study, the horizontal component amplitude observed by ground-based observatories belonged to the INTERMAGNET network have been used to analyze the global pattern variance of the Sq variation. In particular we focused our attention on Vassouras Observatory (VSS), Rio de Janeiro, Brazil, which has been active since 1915. In the next years, a brazilian network of magnetometers will be implemented and VSS can be used as reference. This work aims mainly to highlight and interpret these quiet daily variations over the Brazilian sector compared to the features from other magnetic stations reasonably distributed over the whole Earth's surface. The methodological approach is based on wavelet cross-correlation technique. This technique is useful to isolate the period of the spectral components of geomagnetic field in each station and to correlate them as function of scale (period) between VSS and the other stations. The wavelet cross-correlation coefficient strongly depends on the scale. We study the geomagnetically quiet days at equinox and solstice months during low and high solar activity. As preliminary remarks, the results show that the records in the magnetic stations have primary a latitudinal dependence affected by the time of year and level of solar activity. On the other hand, records of magnetic stations located at the same dip latitude but at different longitude presented some peculiarities. These results indicated that the winds driven the dynamo are very sensitive of the location of the geomagnetic station, i. e., its effects depend upon the direction

  8. Jungle Honey Enhances Immune Function and Antitumor Activity

    Directory of Open Access Journals (Sweden)

    Miki Fukuda

    2011-01-01

    Full Text Available Jungle honey (JH is collected from timber and blossom by wild honey bees that live in the tropical forest of Nigeria. JH is used as a traditional medicine for colds, skin inflammation and burn wounds as well as general health care. However, the effects of JH on immune functions are not clearly known. Therefore, we investigated the effects of JH on immune functions and antitumor activity in mice. Female C57BL/6 mice were injected with JH (1 mg/mouse/day, seven times intra-peritoneal. After seven injections, peritoneal cells (PC were obtained. Antitumor activity was assessed by growth of Lewis Lung Carcinoma/2 (LL/2 cells. PC numbers were increased in JH-injected mice compared to control mice. In Dot Plot analysis by FACS, a new cell population appeared in JH-injected mice. The percent of Gr-1 surface antigen and the intensity of Gr-1 antigen expression of PC were increased in JH-injected mice. The new cell population was neutrophils. JH possessed chemotactic activity for neutrophils. Tumor incidence and weight were decreased in JH-injected mice. The ratio of reactive oxygen species (ROS producing cells was increased in JH-injected mice. The effective component in JH was fractionized by gel filtration using HPLC and had an approximate molecular weight (MW of 261. These results suggest that neutrophils induced by JH possess potent antitumor activity mediated by ROS and the effective immune component of JH is substrate of MW 261.

  9. Protecting patients’ electronic health records using enhanced active bundles

    NARCIS (Netherlands)

    Salih, R.M.; Lilien, L.T.; Ben Othmane, L.; Arriaga, R.; Matic, A.

    2012-01-01

    We propose a solution that provides protection for patients' electronic health/medical records disseminated among different authorized healthcare information systems. The solution is known as Active Bundles using a Trusted Third Party (ABTTP). It is based on the use of trusted third parties, and the

  10. Prior-to-Exam: What Activities Enhance Performance?

    Science.gov (United States)

    Rhoads, C. J.; Healy, Therese

    2013-01-01

    Can instructors impact their student performance by recommending an activity just prior to taking an exam? In this study, college students were randomly assigned to one of three treatment groups (study, exercise, or meditation) or a control group. Each group was given two different types of tests; a traditional concept exam, and a non-traditional…

  11. Enhanced antioxidant activity of polyolefin films integrated with grape tannins.

    Science.gov (United States)

    Olejar, Kenneth J; Ray, Sudip; Kilmartin, Paul A

    2016-06-01

    A natural antioxidant derived from an agro-waste of the wine industry, grape tannin, was incorporated by melt blending into three different polyolefins (high-density polyethylene, linear low-density polyethylene and polypropylene) to introduce antioxidant functionality. Significant antioxidant activity was observed at 1% tannin inclusion in all polymer blends. The antioxidant activity was observed to increase steadily with a greater concentration of grape tannins, the highest increases being seen with polypropylene. The mechanical and thermal properties of the polymer films following antioxidant incorporation were minimally altered with up to 3% grape tannins. All of the polyolefin-grape tannin films successfully passed the leachability test following USP661 standard protocol. Superior antioxidant activity was established in polyolefin thin films by utilization of a bulk grape extract obtained from winery waste. Significant increases in antioxidant activity were seen with 1% extract inclusion. This not only demonstrates the potential for food packaging applications of the polyolefin blends, but also valorizes the agro-waste. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  12. Enhanced 3D face processing using an active vision system

    DEFF Research Database (Denmark)

    Lidegaard, Morten; Larsen, Rasmus; Kraft, Dirk

    2014-01-01

    We present an active face processing system based on 3D shape information extracted by means of stereo information. We use two sets of stereo cameras with different field of views (FOV): One with a wide FOV is used for face tracking, while the other with a narrow FOV is used for face identification...

  13. Intense synaptic activity enhances temporal resolution in spinal motoneurons.

    Directory of Open Access Journals (Sweden)

    Rune W Berg

    Full Text Available In neurons, spike timing is determined by integration of synaptic potentials in delicate concert with intrinsic properties. Although the integration time is functionally crucial, it remains elusive during network activity. While mechanisms of rapid processing are well documented in sensory systems, agility in motor systems has received little attention. Here we analyze how intense synaptic activity affects integration time in spinal motoneurons during functional motor activity and report a 10-fold decrease. As a result, action potentials can only be predicted from the membrane potential within 10 ms of their occurrence and detected for less than 10 ms after their occurrence. Being shorter than the average inter-spike interval, the AHP has little effect on integration time and spike timing, which instead is entirely determined by fluctuations in membrane potential caused by the barrage of inhibitory and excitatory synaptic activity. By shortening the effective integration time, this intense synaptic input may serve to facilitate the generation of rapid changes in movements.

  14. Enhanced Passive and Active Processing of Syllables in Musician Children

    Science.gov (United States)

    Chobert, Julie; Marie, Celine; Francois, Clement; Schon, Daniele; Besson, Mireille

    2011-01-01

    The aim of this study was to examine the influence of musical expertise in 9-year-old children on passive (as reflected by MMN) and active (as reflected by discrimination accuracy) processing of speech sounds. Musician and nonmusician children were presented with a sequence of syllables that included standards and deviants in vowel frequency,…

  15. Microbial enrichment to enhance the disease suppressive activity of compost

    NARCIS (Netherlands)

    Postma, J.; Montenari, M.; Boogert, van den P.H.J.F.

    2003-01-01

    Compost amended soil has been found to be suppressive against plant diseases in various cropping systems. The level and reproducibility of disease suppressive properties of compost might be increased by the addition of antagonists. In the present study, the establishment and suppressive activity of

  16. Enhanced Memory as a Common Effect of Active Learning

    Science.gov (United States)

    Markant, Douglas B.; Ruggeri, Azzurra; Gureckis, Todd M.; Xu, Fei

    2016-01-01

    Despite widespread consensus among educators that "active learning" leads to better outcomes than comparatively passive forms of instruction, it is often unclear why these benefits arise. In this article, we review research showing that the opportunity to control the information experienced while learning leads to improved memory…

  17. Activated platelets enhance IL-10 secretion and reduce TNF-α secretion by monocytes

    DEFF Research Database (Denmark)

    Gudbrandsdottir, Sif; Hasselbalch, Hans C; Nielsen, Claus H

    2013-01-01

    ), Escherichia coli LPS, or intact Porphyromonas gingivalis. Addition of platelets activated by thrombin-receptor-activating peptide enhanced IL-10 production induced by LPS (p gingivalis (p ....05), and P. gingivalis (p gingivalis-stimulated cultures (p ... of activated platelets. Adherence of platelets increased TG- and TT-induced IL-10 secretion by monocytes (p gingivalis (p

  18. Capacitance enhancement of polyaniline coated curved-graphene supercapacitors in a redox-active electrolyte

    KAUST Repository

    Chen, Wei; Baby, Rakhi Raghavan; Alshareef, Husam N.

    2013-01-01

    We show, for the first time, a redox-active electrolyte in combination with a polyaniline-coated curved graphene active material to achieve significant enhancement in the capacitance (36-92% increase) compared to supercapacitors that lack the redox-active

  19. Slow-light enhancement of spontaneous emission in active photonic crystal waveguides

    DEFF Research Database (Denmark)

    Ek, Sara; Chen, Yaohui; Semenova, Elizaveta

    2012-01-01

    Photonic crystal defect waveguides with embedded active layers containing single or multiple quantum wells or quantum dots have been fabricated. Spontaneous emission spectra are enhanced close to the bandedge, consistently with the enhancement of gain by slow light effects. These are promising...... results for future compact devices for terabit/s communication, such as miniaturised semiconductor optical amplifiers and mode-locked lasers....

  20. 77 FR 25188 - Extension of Agency Information Collection Activity Under OMB Review: Enhanced Security...

    Science.gov (United States)

    2012-04-27

    ... general aviation (GA) aircraft operators who wish to fly into and/or out of Ronald Reagan Washington.... Information Collection Requirement Title: Enhanced Security Procedures at Ronald Reagan Washington National...] Extension of Agency Information Collection Activity Under OMB Review: Enhanced Security Procedures at Ronald...

  1. Novel Chiroptical Analysis of Hemoglobin by Surface Enhanced Resonance Raman Optical Activity Spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda; Brazhe, Alexey; Sosnovtseva, Olga

    2010-01-01

    The metalloprotein hemoglobin (Hb) was studied using surface enhanced resonance Raman spectroscopy (SERRS) and surface enhanced resonance Raman optical activity (SERROA). The SERROA results are analyzed and compared with the SERRS, and the later to the resonance Raman (RRS) performed on Hb...

  2. Geomagnetic Survey to Explore High-Temperature Geothermal System in Blawan-Ijen, East Java, Indonesia

    Directory of Open Access Journals (Sweden)

    Daud Yunus

    2018-01-01

    Full Text Available Ijen geothermal area is high-temperature geothermal system located in Bondowoso regency, East Java. It is categorized as caldera-hosted geothermal system which is covered by quaternary andesitic volcanic rocks with steep topography at the surrounding. Several surface thermal manifestations are found, such as altered rocks near Mt. Kukusan and a group of Blawan hotsprings in the northern part of the caldera. Geomagnetic survey was conducted at 72 stations which is distributed inside the caldera to delineate the existence of hydrothermal activity. Magnetic anomaly was obtained by reducing total magnetic measured on the field by IGRF and diurnal variation. Reduction to pole (RTP method was applied with geomagnetic inclination of about -32°. In general, the result shows that high magnetic anomaly is distributed at the boundary of study area, while low magnetic anomaly is observed in the centre. The low anomaly indicates demagnetized rock that probably caused by hydrothermal activity. It has a good correlation with surface alteration observed close to Mt. Kukusan as well as high temperature reservoir drilled in the centre of caldera. Accordingly, the low magnetic anomaly also presents the possibility of geothermal reservoir in Ijen geothermal area.

  3. Geomagnetic Survey to Explore High-Temperature Geothermal System in Blawan-Ijen, East Java, Indonesia

    Science.gov (United States)

    Daud, Yunus; Rosid, Syamsu; Fahmi, Fikri; Yunus, Faris Maulana; Muflihendri, Reza

    2018-02-01

    Ijen geothermal area is high-temperature geothermal system located in Bondowoso regency, East Java. It is categorized as caldera-hosted geothermal system which is covered by quaternary andesitic volcanic rocks with steep topography at the surrounding. Several surface thermal manifestations are found, such as altered rocks near Mt. Kukusan and a group of Blawan hotsprings in the northern part of the caldera. Geomagnetic survey was conducted at 72 stations which is distributed inside the caldera to delineate the existence of hydrothermal activity. Magnetic anomaly was obtained by reducing total magnetic measured on the field by IGRF and diurnal variation. Reduction to pole (RTP) method was applied with geomagnetic inclination of about -32°. In general, the result shows that high magnetic anomaly is distributed at the boundary of study area, while low magnetic anomaly is observed in the centre. The low anomaly indicates demagnetized rock that probably caused by hydrothermal activity. It has a good correlation with surface alteration observed close to Mt. Kukusan as well as high temperature reservoir drilled in the centre of caldera. Accordingly, the low magnetic anomaly also presents the possibility of geothermal reservoir in Ijen geothermal area.

  4. MANGO Imager Network Observations of Geomagnetic Storm Impact on Midlatitude 630 nm Airglow Emissions

    Science.gov (United States)

    Kendall, E. A.; Bhatt, A.

    2017-12-01

    The Midlatitude Allsky-imaging Network for GeoSpace Observations (MANGO) is a network of imagers filtered at 630 nm spread across the continental United States. MANGO is used to image large-scale airglow and aurora features and observes the generation, propagation, and dissipation of medium and large-scale wave activity in the subauroral, mid and low-latitude thermosphere. This network consists of seven all-sky imagers providing continuous coverage over the United States and extending south into Mexico. This network sees high levels of medium and large scale wave activity due to both neutral and geomagnetic storm forcing. The geomagnetic storm observations largely fall into two categories: Stable Auroral Red (SAR) arcs and Large-scale traveling ionospheric disturbances (LSTIDs). In addition, less-often observed effects include anomalous airglow brightening, bright swirls, and frozen-in traveling structures. We will present an analysis of multiple events observed over four years of MANGO network operation. We will provide both statistics on the cumulative observations and a case study of the "Memorial Day Storm" on May 27, 2017.

  5. On the equivalence of the solar wind coupling parameter ε and the magnetospheric energy output parameter UT during intense geomagnetic storms

    International Nuclear Information System (INIS)

    Gonzalez, W.D.; Gonzalez, A.L.C.; Tsurutani, B.T.

    1990-01-01

    For intervals with intense geomagnetic activity it is shown that the solar wind coupling parameter ε and the magnetospheric output parameter U T are equivalent and that ranges of values of ε can be set up in terms of values of the ring current-time constant τ. (author)

  6. 78 FR 47676 - Agency Information Collection Activities; Comment Request; Credit Enhancement for Charter School...

    Science.gov (United States)

    2013-08-06

    ... the use of information technology. Please note that written comments received in response to this... DEPARTMENT OF EDUCATION [Docket No. ED-2013-ICCD-0101] Agency Information Collection Activities; Comment Request; Credit Enhancement for Charter School Facilities Program Performance Report AGENCY...

  7. Nanocaged enzymes with enhanced catalytic activity and increased stability against protease digestion

    Science.gov (United States)

    Zhao, Zhao; Fu, Jinglin; Dhakal, Soma; Johnson-Buck, Alexander; Liu, Minghui; Zhang, Ting; Woodbury, Neal W.; Liu, Yan; Walter, Nils G.; Yan, Hao

    2016-01-01

    Cells routinely compartmentalize enzymes for enhanced efficiency of their metabolic pathways. Here we report a general approach to construct DNA nanocaged enzymes for enhancing catalytic activity and stability. Nanocaged enzymes are realized by self-assembly into DNA nanocages with well-controlled stoichiometry and architecture that enabled a systematic study of the impact of both encapsulation and proximal polyanionic surfaces on a set of common metabolic enzymes. Activity assays at both bulk and single-molecule levels demonstrate increased substrate turnover numbers for DNA nanocage-encapsulated enzymes. Unexpectedly, we observe a significant inverse correlation between the size of a protein and its activity enhancement. This effect is consistent with a model wherein distal polyanionic surfaces of the nanocage enhance the stability of active enzyme conformations through the action of a strongly bound hydration layer. We further show that DNA nanocages protect encapsulated enzymes against proteases, demonstrating their practical utility in functional biomaterials and biotechnology. PMID:26861509

  8. Self-Assembled Complexes of Horseradish Peroxidase with Magnetic Nanoparticles Showing Enhanced Peroxidase Activity

    KAUST Repository

    Corgié , Sté phane C.; Kahawong, Patarawan; Duan, Xiaonan; Bowser, Daniel; Edward, Joseph B.; Walker, Larry P.; Giannelis, Emmanuel P.

    2012-01-01

    Bio-nanocatalysts (BNCs) consisting of horseradish peroxidase (HRP) self-assembled with magnetic nanoparticles (MNPs) enhance enzymatic activity due to the faster turnover and lower inhibition of the enzyme. The size and magnetization of the MNPs

  9. Nanocaged enzymes with enhanced catalytic activity and increased stability against protease digestion

    Science.gov (United States)

    Zhao, Zhao; Fu, Jinglin; Dhakal, Soma; Johnson-Buck, Alexander; Liu, Minghui; Zhang, Ting; Woodbury, Neal W.; Liu, Yan; Walter, Nils G.; Yan, Hao

    2016-02-01

    Cells routinely compartmentalize enzymes for enhanced efficiency of their metabolic pathways. Here we report a general approach to construct DNA nanocaged enzymes for enhancing catalytic activity and stability. Nanocaged enzymes are realized by self-assembly into DNA nanocages with well-controlled stoichiometry and architecture that enabled a systematic study of the impact of both encapsulation and proximal polyanionic surfaces on a set of common metabolic enzymes. Activity assays at both bulk and single-molecule levels demonstrate increased substrate turnover numbers for DNA nanocage-encapsulated enzymes. Unexpectedly, we observe a significant inverse correlation between the size of a protein and its activity enhancement. This effect is consistent with a model wherein distal polyanionic surfaces of the nanocage enhance the stability of active enzyme conformations through the action of a strongly bound hydration layer. We further show that DNA nanocages protect encapsulated enzymes against proteases, demonstrating their practical utility in functional biomaterials and biotechnology.

  10. A general approach toward enhancement of pseudocapacitive performance of conducting polymers by redox-active electrolytes

    KAUST Repository

    Chen, Wei; Xia, Chuan; Baby, Rakhi Raghavan; Alshareef, Husam N.

    2014-01-01

    A general approach is demonstrated where the pseudocapacitive performance of different conducting polymers is enhanced in redox-active electrolytes. The concept is demonstrated using several electroactive conducting polymers, including polyaniline

  11. Silver-enhanced block copolymer membranes with biocidal activity

    KAUST Repository

    Madhavan, Poornima

    2014-11-12

    Silver nanoparticles were deposited on the surface and pore walls of block copolymer membranes with highly ordered pore structure. Pyridine blocks constitute the pore surfaces, complexing silver ions and promoting a homogeneous distribution. Nanoparticles were then formed by reduction with sodium borohydride. The morphology varied with the preparation conditions (pH and silver ion concentration), as confirmed by field emission scanning and transmission electron microscopy. Silver has a strong biocide activity, which for membranes can bring the advantage of minimizing the growth of bacteria and formation of biofilm. The membranes with nanoparticles prepared under different pH values and ion concentrations were incubated with Pseudomonas aeruginosa and compared with the control. The strongest biocidal activity was achieved with membranes containing membranes prepared under pH 9. Under these conditions, the best distribution with small particle size was observed by microscopy.

  12. Enhancement of Antibacterial activity of Chitosan by gamma irradiation

    International Nuclear Information System (INIS)

    Bashandy, A.S.; Ibrahim, H.M.M.

    2006-01-01

    The antibacterial activity of irradiated and non-irradiated chitosan against E.coli, S.aureus, Salmonella, Strep. fecalis,Closteridium and P. aerugenosa was studied. Up to 1.25 mg/l, chitosan hardly suppressed the growth of all the strains while 3 mg/l of chitosan clearly inhibited the growth of all the studied strains. Therefore, the concentration of 3 mg/l of chitosan in the medium was adopted in this study. Irradiation at 100 KGy under dry conditions was effective in increasing the activity of chitosan and the growth of bacterial strains which was completely inhibited. It was also found that the addition of chitosan to dressing membranes present good barrier properties against microbes especially that irradiated at 100 KGy

  13. Silver-enhanced block copolymer membranes with biocidal activity

    KAUST Repository

    Madhavan, Poornima; Hong, Pei-Ying; Sougrat, Rachid; Nunes, Suzana Pereira

    2014-01-01

    Silver nanoparticles were deposited on the surface and pore walls of block copolymer membranes with highly ordered pore structure. Pyridine blocks constitute the pore surfaces, complexing silver ions and promoting a homogeneous distribution. Nanoparticles were then formed by reduction with sodium borohydride. The morphology varied with the preparation conditions (pH and silver ion concentration), as confirmed by field emission scanning and transmission electron microscopy. Silver has a strong biocide activity, which for membranes can bring the advantage of minimizing the growth of bacteria and formation of biofilm. The membranes with nanoparticles prepared under different pH values and ion concentrations were incubated with Pseudomonas aeruginosa and compared with the control. The strongest biocidal activity was achieved with membranes containing membranes prepared under pH 9. Under these conditions, the best distribution with small particle size was observed by microscopy.

  14. Enhanced Efflux Pump Activity in Old Candida glabrata Cells.

    Science.gov (United States)

    Bhattacharya, Somanon; Fries, Bettina C

    2018-03-01

    We investigated the effect of replicative aging on antifungal resistance in Candida glabrata Our studies demonstrate significantly increased transcription of ABC transporters and efflux pump activity in old versus young C. glabrata cells of a fluconazole-sensitive and -resistant strain. In addition, higher tolerance to killing by micafungin and amphotericin B was noted and is associated with higher transcription of glucan synthase gene FKS1 and lower ergosterol content in older cells. Copyright © 2018 American Society for Microbiology.

  15. Lipase Activity Enhancement by SC-CO2 Treatment

    Czech Academy of Sciences Publication Activity Database

    Hlavsová, K.; Wimmer, Zdeněk; Xanthakis, E.; Bernášek, Prokop; Sovová, Helena; Zarevúcka, Marie

    63b, č. 6 (2008), s. 779-784 ISSN 0932-0776 R&D Projects: GA MŠk OC D30.001 Institutional research plan: CEZ:AV0Z50380511; CEZ:AV0Z40720504; CEZ:AV0Z40550506 Keywords : lipase activity * supercritical carbon dioxide * enantioselectivity Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.852, year: 2008 www.znaturforsch.com/ab/v63b/63b0779.pdf

  16. Enhancement of antibiotic activity by Cordia verbenacea DC

    OpenAIRE

    Matias, Edinardo F.F.; Santos, Karla K. A.; Almeida, Thiago S.; Costa, José G.M. da; Coutinho, Henrique D.M.

    2010-01-01

    Escherichia coli is known to produce enterotoxins whose properties and its role in diarrheal disease has been extensively investigated. Some species of Staphylococcus are often recognized as etiological agents of many animal and human opportunistic infections. This study is the first test of change in resistance of antibiotic activity by Cordia verbenacea DC. against multiresistant strains of Escherichia coli and Staphylococcus aureus. In this study, the hexane and methanol extract of Cordia ...

  17. Global ionospheric effects of geomagnetic storm on May 2-3, 2010 and their influence on HF radio wave propagation

    Science.gov (United States)

    Kotova, Daria; Klimenko, Maxim; Klimenko, Vladimir; Zakharov, Veniamin

    2013-04-01

    In this work we have investigated the global ionospheric response to geomagnetic storm on May 2-3, 2010 using GSM TIP (Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere) simulation results. In the GSM TIP storm time model runs, several input parameters such as cross-polar cap potential difference and R2 FAC (Region 2 Field-Aligned Currents) varied as a function of the geomagnetic activity AE-index. Current simulation also uses the empirical model of high-energy particle precipitation by Zhang and Paxton. In this model, the energy and energy flux of precipitating electrons depend on a 3 hour Kp-index. We also have included the 30 min time delay of R2 FAC variations with respect to the variations of cross-polar cap potential difference. In addition, we use the ground-based ionosonde data for comparison our model results with observations. We present an analysis of the physical mechanisms responsible for the ionospheric effects of geomagnetic storms. The obtained simulation results are used by us as a medium for HF radio wave propagation at different latitudes in quiet conditions, and during main and recovery phase of a geomagnetic storm. To solve the problem of the radio wave propagation we used Zakharov's (I. Kant BFU) model based on geometric optics. In this model the solution of the eikonal equation for each of the two normal modes is reduced using the method of characteristics to the integration of the six ray equation system for the coordinates and momentum. All model equations of this system are solved in spherical geomagnetic coordinate system by the Runge-Kutta method. This model was tested for a plane wave in a parabolic layer. In this study, the complex refractive indices of the ordinary and extraordinary waves at ionospheric heights was calculated for the first time using the global first-principal model of the thermosphere-ionosphere system that describes the parameters of an inhomogeneous anisotropic medium during a

  18. Model for Microcapsule Drug Release with Ultrasound-Activated Enhancement.

    Science.gov (United States)

    Tsao, Nadia H; Hall, Elizabeth A H

    2017-11-14

    Microbubbles and microcapsules of silane-polycaprolactone (SiPCL) have been filled with a fluorescent acridium salt (lucigenin) as a model for a drug-loaded delivery vehicle. The uptake and delivery were studied and compared with similar microbubbles and microcapsules of silica/mercaptosilica (S/M/S). Positively charged lucigenin was encapsulated through an electrostatic mechanism, following a Type I Langmuir isotherm as expected, but with an additional multilayer uptake that leads to a much higher loading for the SiPCL system (∼280 μg/2.4 × 10 9 microcapsules compared with ∼135 μg/2.4 × 10 9 microcapsules for S/M/S). Whereas the lucigenin release from the S/M/S bubbles and capsules loaded below the solubility limit is consistent with diffusion from a monolithic structure, the SiPCL structures show distinct release patterns; the Weibull function predicts a general trend for diffusion from normal Euclidean space at short times tending toward diffusion out of fractal spaces with increasing time. As a slow release system, the dissolution time (T d ) increases from 1 to 2 days for the S/M/S and for the low concentration, loaded SiPCl vehicles to ∼10 days for the high loaded microcapsules. However, T d can be reduced on insonation to 2 days, indicating the potential to gain control over the local enhanced release with ultrasound. This was tested for a docetaxel model and its effect on C4-2B prostate cancer cells, showing improved cell toxicity for concentrations below the normal EC 50 in solution.

  19. Activity enhances dopaminergic long-duration response in Parkinson disease

    Science.gov (United States)

    Auinger, Peggy; Fahn, Stanley; Oakes, David; Shoulson, Ira; Kieburtz, Karl; Rudolph, Alice; Marek, Kenneth; Seibyl, John; Lang, Anthony; Olanow, C. Warren; Tanner, Caroline; Schifitto, Giovanni; Zhao, Hongwei; Reyes, Lydia; Shinaman, Aileen; Comella, Cynthia L.; Goetz, Christopher; Blasucci, Lucia M.; Samanta, Johan; Stacy, Mark; Williamson, Kelli; Harrigan, Mary; Greene, Paul; Ford, Blair; Moskowitz, Carol; Truong, Daniel D.; Pathak, Mayank; Jankovic, Joseph; Ondo, William; Atassi, Farah; Hunter, Christine; Jacques, Carol; Friedman, Joseph H.; Lannon, Margaret; Russell, David S.; Jennings, Danna; Fussell, Barbara; Standaert, David; Schwarzschild, Michael A.; Growdon, John H.; Tennis, Marsha; Gauthier, Serge; Panisset, Michel; Hall, Jean; Gancher, Stephen; Hammerstad, John P.; Stone, Claudia; Alexander-Brown, Barbara; Factor, Stewart A.; Molho, Eric; Brown, Diane; Evans, Sharon; Clark, Jeffrey; Manyam, Bala; Simpson, Patricia; Wulbrecht, Brian; Whetteckey, Jacqueline; Martin, Wayne; Roberts, Ted; King, Pamela; Hauser, Robert; Zesiewicz, Theresa; Gauger, Lisa; Trugman, Joel; Wooten, G. Frederick; Rost-Ruffner, Elke; Perlmutter, Joel; Racette, Brad A.; Suchowersky, Oksana; Ranawaya, Ranjit; Wood, Susan; Pantella, Carol; Kurlan, Roger; Richard, Irene; Pearson, Nancy; Caviness, John N.; Adler, Charles; Lind, Marlene; Simuni, Tanya; Siderowf, Andrew; Colcher, Amy; Lloyd, Mary; Weiner, William; Shulman, Lisa; Koller, William; Lyons, Kelly; Feldman, Robert G.; Saint-Hilaire, Marie H.; Ellias, Samuel; Thomas, Cathi-Ann; Juncos, Jorge; Watts, Ray; Partlow, Anna; Tetrud, James; Togasaki, Daniel M.; Stewart, Tracy; Mark, Margery H.; Sage, Jacob I.; Caputo, Debbie; Gould, Harry; Rao, Jayaraman; McKendrick, Ann; Brin, Mitchell; Danisi, Fabio; Benabou, Reina; Hubble, Jean; Paulson, George W.; Reider, Carson; Birnbaum, Alex; Miyasaki, Janis; Johnston, Lisa; So, Julie; Pahwa, Rajesh; Dubinsky, Richard M.; Wszolek, Zbigniew; Uitti, Ryan; Turk, Margaret; Tuite, Paul; Rottenberg, David; Hansen, Joy; Ramos, Serrano; Waters, Cheryl; Lew, Mark; Welsh, Mickie; Kawai, Connie; O'Brien, Christopher; Kumar, Rajeev; Seeberger, Lauren; Judd, Deborah; Barclay, C. Lynn; Grimes, David A.; Sutherland, Laura; Dawson, Ted; Reich, Stephen; Dunlop, Rebecca; Albin, Roger; Frey, Kirk; Wernette, Kristine; Fahn, Stanley; Oakes, David; Shoulson, Ira; Kieburtz, Karl; Rudolph, Alice; Marek, Kenneth; Seibyl, John; Lang, Anthony; Olanow, C. Warren; Tanner, Caroline; Schifitto, Giovanni; Zhao, Hongwei; Reyes, Lydia; Shinaman, Aileen; Comella, Cynthia L.; Goetz, Christopher; Blasucci, Lucia M.; Samanta, Johan; Stacy, Mark; Williamson, Kelli; Harrigan, Mary; Greene, Paul; Ford, Blair; Moskowitz, Carol; Truong, Daniel D.; Pathak, Mayank; Jankovic, Joseph; Ondo, William; Atassi, Farah; Hunter, Christine; Jacques, Carol; Friedman, Joseph H.; Lannon, Margaret; Russell, David S.; Jennings, Danna; Fussell, Barbara; Standaert, David; Schwarzschild, Michael A.; Growdon, John H.; Tennis, Marsha; Gauthier, Serge; Panisset, Michel; Hall, Jean; Gancher, Stephen; Hammerstad, John P.; Stone, Claudia; Alexander-Brown, Barbara; Factor, Stewart A.; Molho, Eric; Brown, Diane; Evans, Sharon; Clark, Jeffrey; Manyam, Bala; Simpson, Patricia; Wulbrecht, Brian; Whetteckey, Jacqueline; Martin, Wayne; Roberts, Ted; King, Pamela; Hauser, Robert; Zesiewicz, Theresa; Gauger, Lisa; Trugman, Joel; Wooten, G. Frederick; Rost-Ruffner, Elke; Perlmutter, Joel; Racette, Brad A.; Suchowersky, Oksana; Ranawaya, Ranjit; Wood, Susan; Pantella, Carol; Kurlan, Roger; Richard, Irene; Pearson, Nancy; Caviness, John N.; Adler, Charles; Lind, Marlene; Simuni, Tanya; Siderowf, Andrew; Colcher, Amy; Lloyd, Mary; Weiner, William; Shulman, Lisa; Koller, William; Lyons, Kelly; Feldman, Robert G.; Saint-Hilaire, Marie H.; Ellias, Samuel; Thomas, Cathi-Ann; Juncos, Jorge; Watts, Ray; Partlow, Anna; Tetrud, James; Togasaki, Daniel M.; Stewart, Tracy; Mark, Margery H.; Sage, Jacob I.; Caputo, Debbie; Gould, Harry; Rao, Jayaraman; McKendrick, Ann; Brin, Mitchell; Danisi, Fabio; Benabou, Reina; Hubble, Jean; Paulson, George W.; Reider, Carson; Birnbaum, Alex; Miyasaki, Janis; Johnston, Lisa; So, Julie; Pahwa, Rajesh; Dubinsky, Richard M.; Wszolek, Zbigniew; Uitti, Ryan; Turk, Margaret; Tuite, Paul; Rottenberg, David; Hansen, Joy; Ramos, Serrano; Waters, Cheryl; Lew, Mark; Welsh, Mickie; Kawai, Connie; O'Brien, Christopher; Kumar, Rajeev; Seeberger, Lauren; Judd, Deborah; Barclay, C. Lynn; Grimes, David A.; Sutherland, Laura; Dawson, Ted; Reich, Stephen; Dunlop, Rebecca; Albin, Roger; Frey, Kirk; Wernette, Kristine; Mendis, Tilak

    2012-01-01

    Objective: We tested the hypothesis that dopamine-dependent motor learning mechanism underlies the long-duration response to levodopa in Parkinson disease (PD) based on our studies in a mouse model. By data-mining the motor task performance in dominant and nondominant hands of the subjects in a double-blind randomized trial of levodopa therapy, the effects of activity and dopamine therapy were examined. Methods: We data-mined the Earlier versus Later Levodopa Therapy in Parkinson's Disease (ELLDOPA) study published in 2005 and performed statistical analysis comparing the effects of levodopa and dominance of handedness over 42 weeks. Results: The mean change in finger-tapping counts from baseline before the initiation of therapy to predose at 9 weeks and 40 weeks increased more in the dominant compared to nondominant hand in levodopa-treated subjects in a dose-dependent fashion. There was no significant difference in dominant vs nondominant hands in the placebo group. The short-duration response assessed by the difference of postdose performance compared to predose performance at the same visit did not show any significant difference between dominant vs nondominant hands. Conclusions: Active use of the dominant hand and dopamine replacement therapy produces synergistic effect on long-lasting motor task performance during “off” medication state. Such effect was confined to dopamine-responsive symptoms and not seen in dopamine-resistant symptoms such as gait and balance. We propose that long-lasting motor learning facilitated by activity and dopamine is a form of disease modification that is often seen in trials of medications that have symptomatic effects. PMID:22459675

  20. Carbohydrate Electrolyte Solutions Enhance Endurance Capacity in Active Females

    Directory of Open Access Journals (Sweden)

    Feng-Hua Sun

    2015-05-01

    Full Text Available The purpose of the present study was to investigate the effects of supplementation with a carbohydrate-electrolyte solution (CES in active females during a prolonged session of submaximal running to exhaustion. Eight healthy active females volunteered to perform a session of open-ended running to exhaustion at 70% of their maximal oxygen consumption on a treadmill during the follicular phase of their menstrual cycle on two occasions. During each run, the subjects consumed either 3mL·kg−1 body mass of a 6% CES or a placebo drink (PL every 20 min during exercise. The trials were administered in a randomized double-blind, cross-over design. During the run, the subjects ingested similar volumes of fluid in two trials (CES: 644 ± 75 mL vs. PL: 593 ± 66 mL, p > 0.05. The time to exhaustion was 16% longer during the CES trial (106.2 ± 9.4 min than during the PL trial (91.6 ± 5.9 min (p < 0.05. At 45 min during exercise, the plasma glucose concentration in the CES trial was higher than that in PL trial. No differences were observed in the plasma lactate level, respiratory exchange ratio, heart rate, perceived rate of exertion, sensation of thirst, or abdominal discomfort between the two trials (p > 0.05. The results of the present study confirm that CES supplementation improves the moderate intensity endurance capacity of active females during the follicular phases of the menstrual cycle. However, the exogenous oxidation of carbohydrate does not seem to explain the improved capacity after CES supplementation.