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Sample records for cme activity cluster

  1. Prediction of Active-Region CME Productivity from Magnetograms

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Gary, G. A.

    2004-01-01

    We report results of an expanded evaluation of whole-active-region magnetic measures as predictors of active-region coronal mass ejection (CME) productivity. Previously, in a sample of 17 vector magnetograms of 12 bipolar active regions observed by the Marshall Space Flight Center (MSFC) vector magnetograph, from each magnetogram we extracted a measure of the size of the active region (the active region s total magnetic flux a) and four measures of the nonpotentiality of the active region: the strong-shear length L(sub SS), the strong-gradient length L(sub SG), the net vertical electric current I(sub N), and the net-current magnetic twist parameter alpha (sub IN). This sample size allowed us to show that each of the four nonpotentiality measures was statistically significantly correlated with active-region CME productivity in time windows of a few days centered on the day of the magnetogram. We have now added a fifth measure of active-region nonpotentiality (the best-constant-alpha magnetic twist parameter (alpha sub BC)), and have expanded the sample to 36 MSFC vector magnetograms of 31 bipolar active regions. This larger sample allows us to demonstrate statistically significant correlations of each of the five nonpotentiality measures with future CME productivity, in time windows of a few days starting from the day of the magnetogram. The two magnetic twist parameters (alpha (sub 1N) and alpha (sub BC)) are normalized measures of an active region s nonpotentially in that they do not depend directly on the size of the active region, while the other three nonpotentiality measures (L(sub SS), L(sub SG), and I(sub N)) are non-normalized measures in that they do depend directly on active-region size. We find (1) Each of the five nonpotentiality measures is statistically significantly correlated (correlation confidence level greater than 95%) with future CME productivity and has a CME prediction success rate of approximately 80%. (2) None of the nonpotentiality

  2. Evolution of two Flaring Active Regions With CME Association

    NASA Astrophysics Data System (ADS)

    Thalmann, J. K.; Wiegelmann, T.

    2008-12-01

    We study the coronal magnetic field structure of two active regions, one during solar activity minimum (June 2007) and another one during a more active time (January 2004). The temporal evolution was explored with the help of nonlinear force-free coronal magnetic field extrapolations of SOLIS/VSM and NAOJ/SFT photospheric vector magnetograms. We study the active region NOAA 10960 observed on 2007 June 7 with three SOLIS/VSM snapshots taken during a small C1.0 flare of time cadence 10 minutes and six snapshots during a quiet period. The total magnetic energy in the active region was approximately 3 × 1025 J. Before the flare the free magnetic energy was about 5~% of the potential field energy. A part of this excess energy was released during the flare, producing almost a potential configuration at the beginning of the quiet period. The return to an almost potential structure can be assigned to a CME as recorded by the SoHO/LASCO instrument on 2007 June 07 around 10 minutes after the flare peaked, so that whatever magnetic helicity was bodily removed from the structure. This was compared with active region 10540 observed on 2004 January 18 -- 21, which was analyzed with the help of vector magnetograph data from the Solar Flare Telescope in Japan of time cadence of about 1 day. The free energy was Efree≈ 66~% of the total energy which was sufficiently high to power a M6.1 flare on January 20, which was associated with a CME 20 minutes later. The activity of AR 10540 was significantly higher than for AR 10960, as was the total magnetic energy. Furthermore, we found the common feature that magnetic energy accumulates before the flare/CME and a significant part of the excess energy is released during the eruption.

  3. Haze activity of different barley trypsin inhibitors of the chloroform/methanol type (BTI-CMe).

    PubMed

    Ye, Lingzhen; Huang, Lu; Huang, Yuqing; Wu, Dezhi; Hu, Hongliang; Li, Chengdao; Zhang, Guoping

    2014-12-15

    Our previous study found that the critical protein in SE (silica eluted) proteins is BTI-CMe, and assumed that SE-ve malt for brewing may improve the haze stability in beer. In this study, we investigated the difference in gene sequence and corresponding amino acid sequence of BTI-CMe between SE+ve and SE-ve types. The results showed that there were 7 amino acid differences between Yerong (SE-ve) and Franklin (SE+ve). Two types BTI-CMe were expressed in vitro and purified successfully. By adding the purified BTI-CMe into commercial beer, we found that both original turbidity and alcohol chill haze degree of beer were increased. BTI-CMe of SE-ve haplotype showed a lower level of haze formation in beer than SE+ve haplotype. Response surface methodology (RSM) was conducted to determine the relationship between BTI-CMe and tannic acid, and their effects on haze formation. It was found that (1) higher content of BTI-CMe and/or tannic acid in beer would give rise to higher turbidity; (2) there was a significant interaction between BTI-CMe and tannic acid; (3) haze activity disparity of BTI-CMe between two types was significantly and positively correlated with the tannic acid concentration. PMID:25038664

  4. Treatment of Viscosity in the Shock Waves Observed After Two Consecutive Coronal Mass Ejection Activities CME08/03/2012 and CME15/03/2012

    NASA Astrophysics Data System (ADS)

    Cavus, Huseyin

    2016-07-01

    A coronal mass ejection (CME) is one of the most the powerful activities of the Sun. There is a possibility to produce shocks in the interplanetary medium after CMEs. Shock waves can be observed when the solar wind changes its velocity from being supersonic nature to being subsonic nature. The investigations of such activities have a central place in space weather purposes, since; the interaction of shocks with viscosity is one of the most important problems in the supersonic and compressible gas flow regime (Blazek in Computational fluid dynamics: principles and applications. Elsevier, Amsterdam 2001). The main aim of present work is to achieve a search for the viscosity effects in the shocks occurred after two consecutive coronal mass ejection activities in 2012 (i.e. CME08/03/2012 and CME15/03/2012).

  5. Why is a Flare-rich Active Region CME-poor?

    NASA Astrophysics Data System (ADS)

    Liu, Lijuan; Wang, Yuming; Wang, Jingxiu; Shen, Chenglong; Ye, Pinzhong; Liu, Rui; Chen, Jun; Zhang, Quanhao; Wang, S.

    2016-08-01

    Solar active regions (ARs) are the major sources of two of the most violent solar eruptions, namely flares and coronal mass ejections (CMEs). The largest AR in the past 24 years, NOAA AR 12192, which crossed the visible disk from 2014 October 17 to 30, unusually produced more than one hundred flares, including 32 M-class and 6 X-class ones, but only one small CME. Flares and CMEs are believed to be two phenomena in the same eruptive process. Why is such a flare-rich AR so CME-poor? We compared this AR with other four ARs; two were productive in both and two were inert. The investigation of the photospheric parameters based on the SDO/HMI vector magnetogram reveals that the flare-rich AR 12192, as with the other two productive ARs, has larger magnetic flux, current, and free magnetic energy than the two inert ARs but, in contrast to the two productive ARs, it has no strong, concentrated current helicity along both sides of the flaring neutral line, indicating the absence of a mature magnetic structure consisting of highly sheared or twisted field lines. Furthermore, the decay index above the AR 12192 is relatively low, showing strong constraint. These results suggest that productive ARs are always large and have enough current and free energy to power flares, but whether or not a flare is accompanied by a CME is seemingly related to (1) the presence of a mature sheared or twisted core field serving as the seed of the CME, or (2) a weak enough constraint of the overlying arcades.

  6. Why Is the Great Solar Active Region 12192 Flare-rich but CME-poor?

    NASA Astrophysics Data System (ADS)

    Sun, Xudong; Bobra, Monica G.; Hoeksema, J. Todd; Liu, Yang; Li, Yan; Shen, Chenglong; Couvidat, Sebastien; Norton, Aimee A.; Fisher, George H.

    2015-05-01

    Solar active region (AR) 12192 of 2014 October hosts the largest sunspot group in 24 years. It is the most prolific flaring site of Cycle 24 so far, but surprisingly produced no coronal mass ejection (CME) from the core region during its disk passage. Here, we study the magnetic conditions that prevented eruption and the consequences that ensued. We find AR 12192 to be “big but mild” its core region exhibits weaker non-potentiality, stronger overlying field, and smaller flare-related field changes compared to two other major flare-CME-productive ARs (11429 and 11158). These differences are present in the intensive-type indices (e.g., means) but generally not the extensive ones (e.g., totals). AR 12192's large amount of magnetic free energy does not translate into CME productivity. The unexpected behavior suggests that AR eruptiveness is limited by some relative measure of magnetic non-potentiality over the restriction of background field, and that confined flares may leave weaker photospheric and coronal imprints compared to their eruptive counterparts.

  7. Why Is the Great Solar Active Region 12192 CME-Poor?

    NASA Astrophysics Data System (ADS)

    Sun, Xudong; Bobra, Monica G.; Hoeksema, Todd; Liu, Yang; Li, Yan; Shen, Chenglong; Couvidat, Sebastien; Norton, Aimee A.; Fisher, George H.

    2015-04-01

    Solar active region (AR) 12192 of October 2014 hosts the largest sunspot group in 24 years. It is the most prolific flaring site of Cycle 24, but surprisingly produced no coronal mass ejection (CME) from the core region during its disk passage. Here, we study the magnetic conditions that prevented eruption and the consequences that ensued. We find AR 12192 to be "big but mild"; its core region exhibits weaker non-potentiality, stronger overlying field, and smaller flare-related field changes compared to two other major flare-CME-productive ARs (11429 and 11158). These differences are present in the intensive-type indices (e.g., means) but generally not the extensive ones (e.g., totals). AR 12192's large amount of magnetic free energy does not translate into CME productivity. The unexpected behavior suggests that AR eruptiveness is limited by some relative measure of magnetic non-potentiality over the restriction of background field, and that confined flares may leave weaker photospheric and coronal imprints compared to their eruptive counterparts.

  8. Solar Back-sided Halo CME

    NASA Video Gallery

    The Sun erupted with several CMEs (coronal mass ejections) during a period just over a day (Nov. 8-9, 2012), the largest of which was a halo CME. This CME appears to have originated from an active ...

  9. Photospheric Vector Magnetic Field Evolution of NOAA Active Region 11504 and the Ensuing CME

    NASA Astrophysics Data System (ADS)

    James, Alexander; Green, Lucie; Valori, Gherardo; van Driel-Gesztelyi, Lidia; Baker, Deborah; Brooks, David; Palmerio, Erika

    2016-05-01

    Coronal mass ejections (CMEs) are eruptions of billions of tonnes of plasma from the Sun that drive the most severe space weather effects we observe. In order to be able to produce forecasts of space weather with lead times of the order of days, accurate predictions of the occurrence of CMEs must be developed. The eruptive active-region studied in this work (NOAA 11504) is complex, featuring fragmentation of penumbral magnetic field in the days prior to eruption, as well as rotation of the leading sunspot. SDO/HMI vector photospheric magnetic field measurements are utilised alongside SDO/AIA multi-wavelength extreme ultra-violet (EUV) observations to study the dynamics of the photospheric and coronal structures, as well as Hinode/EIS spectroscopic measurements, including elemental composition data. The EUV data show flare ribbons as well as coronal dimmings, which are used to infer the orientation of the erupting flux rope. This flux rope orientation is then compared to in situ measurements of the flux rope. The vector magnetic field data is used to determine the possible contributions the field fragmentation and sunspot rotation may have made to the formation of the flux rope and the triggering of the CME.

  10. "Academic" CME and the social contract.

    PubMed

    Davis, D; Parboosingh, J

    1993-05-01

    The term academic continuing medical education (CME) is defined and explored from the perspective of forces that have made its usage necessary. These forces include the new understandings of the place, impact, and scope of CME, and, in particular, the increasing entrepreneurial interests in the field, unrelated to the improvement of physicians' competence or performance, or to health care outcomes. In addition to principles of CME provision promulgated by the Accreditation Council of CME, and those of ethical CME providers, academic CME implies the critical appraisal of the providers' activities, the creation of new knowledge about how physicians learn and change, and the dissemination of information based on such knowledge. Finally, the nature of academic CME providers is discussed, and the potential role of CME in fostering the social contract between the medical professional and society is explored. PMID:8484835

  11. Enhancing Quality Improvements in Cancer Care Through CME Activities at a Nationally Recognized Cancer Center

    PubMed Central

    Uemura, Marc; Morgan, Robert; Mendelsohn, Mary; Kagan, Jean; Saavedra, Crystal; Leong, Lucille

    2013-01-01

    Changing healthcare policy will undoubtedly affect the healthcare environment in which providers function. The current Fee for Service reimbursement model will be replaced by Value-Based Purchasing, where higher quality and more efficient care will be emphasized. Because of this, large healthcare organizations and individual providers must adapt to incorporate performance outcomes into patient care. Here, we present a Continuing Medical Education (CME)-based initiative at the City of Hope National Cancer Center that we believe can serve as a model for using CME as a value added component to achieving such a goal. PMID:23608956

  12. Real-Time CME Forecasting Using HMI Active-Region Magnetograms and Flare History

    NASA Technical Reports Server (NTRS)

    Falconer, David; Moore, Ron; Barghouty, Abdulnasser F.; Khazanov, Igor

    2011-01-01

    We have recently developed a method of predicting an active region s probability of producing a CME, an X-class Flare, an M-class Flare, or a Solar Energetic Particle Event from a free-energy proxy measured from SOHO/MDI line-of-sight magnetograms. This year we have added three major improvements to our forecast tool: 1) Transition from MDI magnetogram to SDO/HMI magnetogram allowing us near-real-time forecasts, 2) Automation of acquisition and measurement of HMI magnetograms giving us near-real-time forecasts (no older than 2 hours), and 3) Determination of how to improve forecast by using the active region s previous flare history in combination with its free-energy proxy. HMI was turned on in May 2010 and MDI was turned off in April 2011. Using the overlap period, we have calibrated HMI to yield what MDI would measure. This is important since the value of the free-energy proxy used for our forecast is resolution dependent, and the forecasts are made from results of a 1996-2004 database of MDI observations. With near-real-time magnetograms from HMI, near-real-time forecasts are now possible. We have augmented the code so that it continually acquires and measures new magnetograms as they become available online, and updates the whole-sun forecast from the coming day. The next planned improvement is to use an active region s previous flare history, in conjunction with its free-energy proxy, to forecast the active region s event rate. It has long been known that active regions that have produced flares in the past are likely to produce flares in the future, and that active regions that are nonpotential (have large free-energy) are more likely to produce flares in the future. This year we have determined that persistence of flaring is not just a reflection of an active region s free energy. In other words, after controlling for free energy, we have found that active regions that have flared recently are more likely to flare in the future.

  13. Use of Yohkoh SXT in Measuring the Net Current and CME Productivity of Active Regions

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Gary, G. A.; Six, N. Frank (Technical Monitor)

    2001-01-01

    In our investigation of the correlation of global nonpotentiality of active regions to their CME productivity (Falconer, D.A. 2001, JGR, in press, and Falconer, Moore, & Gary, 2000, EOS 82, 20 S323), we use Yohkoh SXT images for two purposes. The first use is to help resolve the 180 degree ambiguity in the direction of the observed transverse magnetic field. Resolution of the 180 degree ambiguity is important, since the net current, one of our measures of global nonpotentiality, is derived from integrating the dot product of the transverse field around a contour (I(sub N)=(integral)BT(raised dot)dl). The ambiguity results from the observed transverse field being determined from the linear polarization, which gives the plane of the direction, but leaves a 180 degrees ambiguity. Automated methods to resolve the ambiguity ranging from the simple acute angle rule (Falconer, D.A. 2001) to the more sophisticated annealing method (Metcalf T.R. 1994). For many active regions, especially ones that are nearly potential these methods work well. But for very nonpotential active regions where the shear angle (the angle between the observed and potential transverse field) is near 90 degrees throughout large swaths along the main neutral line, both methods can resolve the ambiguity incorrectly for long segments of the neutral line. By determining from coronal images, such as those from Yohkoh/SXT, the sense of shear along the main neutral line in the active region, these cases can be identified and corrected by a modification of the acute angle rule described here. The second use of Yohkoh/SXT in this study is to check for the cusped coronal arcades of long-duration eruptive flares. This signature is an excellent proxy for CMEs, and was used by Canfield, Hudson, and McKenzie (1999 GRL V26, 6, 627-630). This work is funded by NSF through the Space Weather Program and by NASA through the Solar Physics Supporting Research and Technology Program.

  14. Correlation of the CME Productivity of Solar Active Regions with Measures of their Global Nonpotentiality from Vector Magnetograms: Baseline Results

    NASA Technical Reports Server (NTRS)

    Falconer, David A.; Moore, Ron L.; Gary, G. Allen; Six, N. Frank (Technical Monitor)

    2001-01-01

    From conventional magnetograms and chromospheric and coronal images, it is known qualitatively that the fastest coronal mass ejections (CMEs) are magnetic explosions from sunspot active regions in which the magnetic field is globally strongly sheared and twisted from its minimum-energy potential configuration. In this paper, we present measurements from active-region vector magnetograms that begin to quantify the dependence of the CME productivity of an active region on the global nonpotentiality of its magnetic field. From each of 17 magnetograms of 12 bipolar active regions, we obtain a measure of the size of the active region (the magnetic flux content, phi) and three different measures of the global nonpotentiality (L(sub SS), the length of strong-shear, strong-field main neutral line; I(sub N), the net electric current arching from one polarity to the other; and alpha = muI(subN/phi), a flux-normalized measure of the field twist).

  15. The Cluster Active Archive

    NASA Astrophysics Data System (ADS)

    Laakso, H.; Perry, C. H.; Escoubet, C. P.; McCaffrey, S.; Herment, D.; Esson, S.; Bowen, H.; Buggy, O.; Taylor, M. G.

    2008-05-01

    The four-satellite Cluster mission investigates small-scale structures (in three dimensions) of the Earth's plasma environment, such as those involved in the interaction between the solar wind and the magnetospheric plasma, in global magnetotail dynamics, in cross-tail currents, and in the formation and dynamics of the neutral line and of plasmoids. The Cluster Active Archive CAA (http://caa.estec.esa.int/) will contain the entire set of Cluster high resolution data and other allied products in a standard format and with a complete set of metadata in machine readable form. The data archived are (1) publicly accessible, (2) of the best quality achievable with the given resources, and (3) suitable for science use and publication by both the Cluster and broader scientific community. The CAA to provide user friendly services for searching and accessing these data, e.g. users can save and restore their selections speeding up similar requests. The CAA is continuing to extend and improve the online capabilities of the system, e.g., the CAA products can be downloaded either via a web interface or a machine accessible interface.

  16. Cluster Active Archive: Overview

    NASA Astrophysics Data System (ADS)

    Laakso, H.; Perry, C.; McCaffrey, S.; Herment, D.; Allen, A. J.; Harvey, C. C.; Escoubet, C. P.; Gruenberger, C.; Taylor, M. G. G. T.; Turner, R.

    The four-satellite Cluster mission investigates the small-scale structures and physical processes related to interaction between the solar wind and the magnetospheric plasma. The Cluster Active Archive (CAA) (URL: http://caa.estec.esa.int) will contain the entire set of Cluster high-resolution data and other allied products in a standard format and with a complete set of metadata in machine readable format. The total amount of the data files in compressed format is expected to exceed 50 TB. The data archive is publicly accessible and suitable for science use and publication by the world-wide scientific community. The CAA aims to provide user-friendly services for searching and accessing these data and ancillary products. The CAA became operational in February 2006 and as of Summer 2008 has data from most of the Cluster instruments for at least the first 5 years of operations (2001-2005). The coverage and range of products are being continually improved with more than 200 datasets available from each spacecraft, including high-resolution magnetic and electric DC fields and wave spectra; full three-dimensional electron and ion distribution functions from a few eV to hundreds of keV; and various ancillary and browse products to help with spacecraft and event location. The CAA is continuing to extend and improve the online capabilities of the system and the quality of the existing data. It will add new data files for years 2006-2009 and is preparing for the long-term archive with complete coverage after the completion of the Cluster mission.

  17. Assessment of Barriers to Changing Practice as CME Outcomes

    ERIC Educational Resources Information Center

    Price, David W.; Miller, Elaine K.; Rahm, Alanna Kulchak; Brace, Nancy E.; Larson, R. Sam

    2010-01-01

    Introduction: Continuing medical education (CME) is meant to drive and support improvements in practice. To achieve this goal, CME activities must move beyond simply purveying knowledge, instead helping attendees to contextualize information and to develop strategies for implementing new learning. CME attendees face different barriers to…

  18. CME Theory and Models

    NASA Astrophysics Data System (ADS)

    Forbes, T. G.; Linker, J. A.; Chen, J.; Cid, C.; Kóta, J.; Lee, M. A.; Mann, G.; Mikić, Z.; Potgieter, M. S.; Schmidt, J. M.; Siscoe, G. L.; Vainio, R.; Antiochos, S. K.; Riley, P.

    This chapter provides an overview of current efforts in the theory and modeling of CMEs. Five key areas are discussed: (1) CME initiation; (2) CME evolution and propagation; (3) the structure of interplanetary CMEs derived from flux rope modeling; (4) CME shock formation in the inner corona; and (5) particle acceleration and transport at CME driven shocks. In the section on CME initiation three contemporary models are highlighted. Two of these focus on how energy stored in the coronal magnetic field can be released violently to drive CMEs. The third model assumes that CMEs can be directly driven by currents from below the photosphere. CMEs evolve considerably as they expand from the magnetically dominated lower corona into the advectively dominated solar wind. The section on evolution and propagation presents two approaches to the problem. One is primarily analytical and focuses on the key physical processes involved. The other is primarily numerical and illustrates the complexity of possible interactions between the CME and the ambient medium. The section on flux rope fitting reviews the accuracy and reliability of various methods. The section on shock formation considers the effect of the rapid decrease in the magnetic field and plasma density with height. Finally, in the section on particle acceleration and transport, some recent developments in the theory of diffusive particle acceleration at CME shocks are discussed. These include efforts to combine self-consistently the process of particle acceleration in the vicinity of the shock with the subsequent escape and transport of particles to distant regions.

  19. CME Theory and Models

    NASA Astrophysics Data System (ADS)

    Forbes, T. G.; Linker, J. A.; Chen, J.; Cid, C.; Kóta, J.; Lee, M. A.; Mann, G.; Mikić, Z.; Potgieter, M. S.; Schmidt, J. M.; Siscoe, G. L.; Vainio, R.; Antiochos, S. K.; Riley, P.

    2006-03-01

    This chapter provides an overview of current efforts in the theory and modeling of CMEs. Five key areas are discussed: (1) CME initiation; (2) CME evolution and propagation; (3) the structure of interplanetary CMEs derived from flux rope modeling; (4) CME shock formation in the inner corona; and (5) particle acceleration and transport at CME driven shocks. In the section on CME initiation three contemporary models are highlighted. Two of these focus on how energy stored in the coronal magnetic field can be released violently to drive CMEs. The third model assumes that CMEs can be directly driven by currents from below the photosphere. CMEs evolve considerably as they expand from the magnetically dominated lower corona into the advectively dominated solar wind. The section on evolution and propagation presents two approaches to the problem. One is primarily analytical and focuses on the key physical processes involved. The other is primarily numerical and illustrates the complexity of possible interactions between the CME and the ambient medium. The section on flux rope fitting reviews the accuracy and reliability of various methods. The section on shock formation considers the effect of the rapid decrease in the magnetic field and plasma density with height. Finally, in the section on particle acceleration and transport, some recent developments in the theory of diffusive particle acceleration at CME shocks are discussed. These include efforts to combine self-consistently the process of particle acceleration in the vicinity of the shock with the subsequent escape and transport of particles to distant regions.

  20. Improved Cardiovascular Prevention Using Best CME Practices: A Randomized Trial

    ERIC Educational Resources Information Center

    Laprise, Rejean; Thivierge, Robert; Gosselin, Gilbert; Bujas-Bobanovic, Maja; Vandal, Sylvie; Paquette, Daniel; Luneau, Micheline; Julien, Pierre; Goulet, Serge; Desaulniers, Jean; Maltais, Paule

    2009-01-01

    Introduction: It was hypothesized that after a continuing medical education (CME) event, practice enablers and reinforcers addressing main clinical barriers to preventive care would be more effective in improving general practitioners' (GPs) adherence to cardiovascular guidelines than a CME event only. Methods: A cluster-randomized trial was…

  1. CME - Coming At You

    NASA Video Gallery

    An oldie but goody: The September 12, 2000 coronal mass ejection (CME), which moves directly from the sun's surface toward the viewer. This was recorded by the Solar and Heliospheric Observatory (S...

  2. Active matter clusters at interfaces

    NASA Astrophysics Data System (ADS)

    Copenhagen, Katherine; Gopinathan, Ajay

    Collective and directed motility or swarming is an emergent phenomenon displayed by many self-organized assemblies of active biological matter such as clusters of embryonic cells during tissue development and flocks of birds. Such clusters typically encounter very heterogeneous environments. What happens when a cluster encounters an interface between two different environments has implications for its function and fate. Here we study this problem by using a mathematical model of a cluster that treats it as a single cohesive unit whose movement depends on the nature of the local environment. We find that low speed clusters which exert forces but no active torques, encountering an interface with a moderate difference in properties can lead to refraction or even total internal reflection of the cluster. For large speeds and clusters with active torques, they show more complex behaviors crossing the interface multiple times, becoming trapped at the interface and deviating from the predictable refraction and reflection of the low velocity clusters. Our results show a wide range of behaviors that occur when collectively moving active biological matter moves across interfaces and these insights can be used to control motion by patterning environments.

  3. Active matter clusters at interfaces.

    NASA Astrophysics Data System (ADS)

    Copenhagen, Katherine; Gopinathan, Ajay

    2016-03-01

    Collective and directed motility or swarming is an emergent phenomenon displayed by many self-organized assemblies of active biological matter such as clusters of embryonic cells during tissue development, cancerous cells during tumor formation and metastasis, colonies of bacteria in a biofilm, or even flocks of birds and schools of fish at the macro-scale. Such clusters typically encounter very heterogeneous environments. What happens when a cluster encounters an interface between two different environments has implications for its function and fate. Here we study this problem by using a mathematical model of a cluster that treats it as a single cohesive unit that moves in two dimensions by exerting a force/torque per unit area whose magnitude depends on the nature of the local environment. We find that low speed (overdamped) clusters encountering an interface with a moderate difference in properties can lead to refraction or even total internal reflection of the cluster. For large speeds (underdamped), where inertia dominates, the clusters show more complex behaviors crossing the interface multiple times and deviating from the predictable refraction and reflection for the low velocity clusters. We then present an extreme limit of the model in the absence of rotational damping where clusters can become stuck spiraling along the interface or move in large circular trajectories after leaving the interface. Our results show a wide range of behaviors that occur when collectively moving active biological matter moves across interfaces and these insights can be used to control motion by patterning environments.

  4. Online CME usage patterns.

    PubMed

    Mazzoleni, M Cristina; Rognoni, Carla; Finozzi, Enrico; Giorgi, Ines; Pagani, Marco; Imbriani, Marcello

    2011-01-01

    The paper reports the findings of the analysis of a sample of 829 online Continuous Medical Education (CME) enrolments aimed at inspecting users' preferences and behaviours. The contents of the analyzed course are provided as online SCORM (Sharable Content Object Reference Model) resources together with the corresponding Pdf downloadable versions allowing different usage patterns (online only, Pdf only, online AND Pdf, mixed online OR Pdf). The results point out that there is not a specific preference for one of the four patterns and that most of the users access both navigable modules and Pdf documents. Demographic characteristics and initial knowledge level do not influence the choice of a specific usage pattern that probably depends on internal or context factors. From the point of view of knowledge acquisition, the four patterns are equivalent. As regards users' behaviour, the analysis has pointed out two issues: 1) the attitude to conclude the course in a short time and to reach good test scores, but not the excellence; 2) learning activity tracing data were not available for all the enrolments. Cues for discussion are proposed. PMID:21893749

  5. The CME Flare Arcade and the Width of the CME in the Outer Corona

    NASA Technical Reports Server (NTRS)

    Moore, Ron; Falconer, David; Sterling, Alphonse

    2008-01-01

    Moore, Sterling, & Suess (2007, ApJ, 668, 1221) present evidence that (1) a CME is typically a magnetic bubble, a low-beta gplasmoid with legs h having roughly the 3D shape of a light bulb, and (2) in the outer corona the CME plasmoid is in lateral pressure equilibrium with the ambient magnetic field. They present three CMEs observed by SOHO/LASCO, each from a very different source located near the limb. One of these CMEs came from a compact ejective eruption from a small part of a sunspot active region, another came from a large quiet-region filament eruption, and the third CME, an extremely large and fast one, was produced in tandem with an X20 flare arcade that was centered on a huge delta sunspot. Each of these CMEs had more or less the classic lightbulb silhouette and attained a constant heliocentric angular width in the outer corona. This indicates that the CME plasmoid attained lateral magnetic pressure balance with the ambient radial magnetic field in the outer corona. This lateral pressure balance, together with the standard scenario for CME production by the eruption of a sheared-core magnetic arcade, yields the following simple estimate of the strength B(sub Flare) of the magnetic field in the flare arcade produced together with the CME: B(sub Flare) 1.4(theta CME/theta Flare)sup 2 G, where theta (sub CME) is the heliocentric angular width of the CME plasmoid in the outer corona and theta (sub Flare) is the heliocentric angular width of the full-grown flare arcade. Conversely, theta (sub CME) approximately equal to (R(sub Sun)sup -1(phi(sub Flare)/1.4)sup 1/2 radians, where Flare is the magnetic flux covered by the full-grown flare arcade. In addition to presenting the three CMEs of Moore, Sterling, & Suess (2007) and their agreement with this relation between CME and Flare, we present a further empirical test of this relation. For CMEs that erupt from active regions, the co-produced flare arcade seldom if ever covers the entire active region: if AR is

  6. 01.22.12: SOHO's View of Earth-directed CME

    NASA Video Gallery

    The Solar Heliospheric Observatory captured the coronal mass ejection (CME) in this video (which shows the sun's activity from January 19 to January 23). The CME is associate with an M8.7 class sol...

  7. Characteristics That Predict Physician Participation in a Web-Based CME Activity: The MI-Plus Study

    PubMed Central

    Schoen, Michael J.; Tipton, Edmond F.; Houston, Thomas K.; Funkhouser, Ellen; Levine, Deborah A.; Estrada, Carlos A.; Allison, Jeroan J.; Williams, O. Dale; Kiefe, Catarina I.

    2011-01-01

    Introduction Physician use of the Internet for practice improvement has increased dramatically over the last decade, but research shows that many physicians choose not to participate. The current study investigated the association of specific physician characteristics with enrollment rates and intensity of participation in a specific Internet-delivered educational intervention to improve care to post–myocardial infarction (MI) patients. Methods Primary-care physicians were recruited for participation in a randomized controlled trial designed to compare effectiveness of an intervention Web site versus a control Web site in the management of adult chronic disease. Physicians were informed that the intervention focused on ambulatory post–myocardial infarction patients. Physician characteristics were obtained from a commercial vendor with data merged from the American Medical Association and Alabama State Licensing Board. Enrollment and Web use were tracked electronically. Results Out of a sample of 1337 eligible physicians, 177 (13.2%) enrolled in the study. Enrollment was higher for physicians with more post-MI patients (≥20 vs < 20 patients, 15.3% vs 9.3%, P = .002) and for those practicing in rural compared to urban areas (16.3% vs 12.1%, P = .046). Intensity of use of the Internet courses after initial enrollment was not predicted by physician characteristics in the current sample. Discussion Physicians with more post-MI patients and rural practice location were found to predict enrollment in an Internet-delivered continuing medical education (CME) intervention designed to improve care for post-MI patients. These factors predicted program interest but not program use. More research is needed to replicate these findings to investigate variables that determine physician engagement in Internet CME. PMID:19998447

  8. CME Kinematics and Dynamics

    NASA Astrophysics Data System (ADS)

    Lin, C.-H.; Gallagher, P. T.

    The goal of this study is to investigate the driving mechanisms of CMEs and to infer the magnetic field properties at the onset of the instability. We use EIT 195 Å images and LASCO white-light coronagraph data of a CME event that occurred on 17 December 2006. It was a long-duration event, and was associated with an occulted C2.1 class flare. To determine the driving mechanism, we quantitatively and qualitatively compared the observationally obtained kinematic evolution with that predicted by three CME models: the breakout model (BO, see Antiochos et al. 1999; Lynch et al. 2008; DeVore and Antiochos 2008), the catastrophe model (CM, see Priest and Forbes 2000), and the toroidal instability model (TI, see Chen 1989; Kliem and Török 2006). Our results indicate that this CME is best represented by the CM model. We infer that, at the onset of the instability, the Alfvén speed is approximately 120 km s-1 and the height of the flux rope is roughly 100-200Mm. These parameter values are related to the magnetic environment and the loop geometry and can be used to infer the magnetic condition at the onset of the eruption.We intend to submit the full analysis to A&A.

  9. On Flare and CME Predictability Based on Sunspot Group Evolution

    NASA Astrophysics Data System (ADS)

    Korsós, M. B.; Ruderman, M. S.

    2016-04-01

    We propose to apply the weighted horizontal magnetic gradient (WGM), introduced in Korsós et al. (2015), for analysing the pre-flare and pre-CME behaviour and evolution of Active Regions (ARs) using the SDO/HMI-Debrecen Data catalogue. To demonstrate the power of investigative capabilities of the WGM method in terms of flare/CME eruptions, we show the results of studying three typical active regions, namely, AR11818, AR12017 and AR11495. The choice of ARs represent typical cases of flaring with a fast CME, flare eruption without a CME and non-flaring cases, respectively. AR11818 produced an M1.4 energetic flare with a fast "halo" CME (vlinear=1202 km/s) while in AR12017 occurred an X1.0 flare without a CME. The AR11495 is a good example for non-flaring ARs. The value and temporal variation of WGM is found to possess potentially important diagnostic information about the intensity of expected flares. However, this test turns out not only to provide information about the intensity of expected flares but may also show whether a flare will occur with/without a fast CME.

  10. CME impact on comet 67P

    NASA Astrophysics Data System (ADS)

    Edberg, Niklas J. T.; Andrews, David J.; Burch, Jim L.; Carr, Christopher M.; Cupido, Emanuele; Eriksson, Anders I.; Glassmeier, Karl-Heinz; Goldstein, Ray; Henri, Pierre; Koenders, Christoph; Mandt, Kathy; Nilsson, Hans; Odelstad, Elias; Stenberg Wieser, Gabriella; Vigren, Erik

    2016-04-01

    We present observations from the Rosetta Plasma Consortium (RPC) of an impact of a coronal mass ejection (CMEs) on comet 67P. The CME impacted during a dayside excursion in early October 2015 when Rosetta slowly moved from a distance of ~300 km to 1500 km from the comet nucleus. Although this was still deep down in the cometary coma, the CME impact caused a significant disturbance to the plasma environment. As the CME impacted, the magnetic field strength increased to reach a maximum of 250 nT, which is the highest magnetic field strength ever observed at 67P. Lots of magnetic field oscillations and increased fluxes of energized (~100 eV) electrons and ions were observed concurrently, and the ionospheric low-energy plasma density increased by roughly one order of magnitude. An interesting phenomenon that could occur during a CME impact is a so-called tail disconnection event, when magnetic reconnection, either on the dayside of the comet or in the tail, causes a large fraction of the tail to be disconnected from the comet. Rosetta, being relatively close to the nucleus, can at best directly observe signatures of dayside reconnection when draped interplanetary magnetic fields of different polarities convects through the plasma environment and reconnects at the location of Rosetta. Rosetta cannot directly observe any tail-side disconnection event due to the orbit constraints. However, signatures of such events might resemble substorm effects in the terrestrial ionosphere with increased wave activity, increased ionization, energization of electrons and possibly ions. We discuss the RPC measurements during the October CME in this context and try to determine if a tail disconnection event could have occurred at this time.

  11. Ensemble modeling of CME propagation

    NASA Astrophysics Data System (ADS)

    Lee, C. O.; Arge, C. N.; Henney, C. J.; Odstrcil, D.; Millward, G. H.; Pizzo, V. J.

    2014-12-01

    The Wang-Sheeley-Arge(WSA)-Enlil-cone modeling system is used for making routine arrival time forecasts of the Earth-directed "halo" coronal mass ejections (CMEs), since they typically produce the most geoeffective events. A major objective of this work is to better understand the sensitivity of the WSA-Enlil modeling results to input model parameters and how these parameters contribute to the overall model uncertainty and performance. We present ensemble modeling results for a simple halo CME event that occurred on 15 February 2011 and a succession of three halo CME events that occurred on 2-4 August 2011. During this period the Solar TErrestrial RElations Observatory (STEREO) A and B spacecraft viewed the CMEs over the solar limb, thereby providing more reliable constraints on the initial CME geometries during the manual cone fitting process. To investigate the sensitivity of the modeled CME arrival times to small variations in the input cone properties, for each CME event we create an ensemble of numerical simulations based on multiple sets of cone parameters. We find that the accuracy of the modeled arrival times not only depends on the initial input CME geometry, but also on the reliable specification of the background solar wind, which is driven by the input maps of the photospheric magnetic field. As part of the modeling ensemble, we simulate the CME events using the traditional daily updated maps as well as those that are produced by the Air Force data Assimilative Photospheric flux Transport (ADAPT) model, which provide a more instantaneous snapshot of the photospheric field distribution. For the August 2011 events, in particular, we find that the accuracy in the arrival time predictions also depends on whether the cone parameters for all three CMEs are specified in a single WSA-Enlil simulation. The inclusion/exclusion of one or two of the preceding CMEs affects the solar wind conditions through which the succeeding CME propagates.

  12. Cluster Active Archive: lessons learnt

    NASA Astrophysics Data System (ADS)

    Laakso, H. E.; Perry, C. H.; Taylor, M. G.; Escoubet, C. P.; Masson, A.

    2010-12-01

    The ESA Cluster Active Archive (CAA) was opened to public in February 2006 after an initial three-year development phase. It provides access (both web GUI and command-line tool are available) to the calibrated full-resolution datasets of the four-satellite Cluster mission. The data archive is publicly accessible and suitable for science use and publication by the world-wide scientific community. There are more than 350 datasets from each spacecraft, including high-resolution magnetic and electric DC and AC fields as well as full 3-dimensional electron and ion distribution functions and moments from a few eV to hundreds of keV. The Cluster mission has been in operation since February 2001, and currently although the CAA can provide access to some recent observations, the ingestion of some other datasets can be delayed by a few years due to large and difficult calibration routines of aging detectors. The quality of the datasets is the central matter to the CAA. Having the same instrument on four spacecraft allows the cross-instrument comparisons and provide confidence on some of the instrumental calibration parameters. Furthermore it is highly important that many physical parameters are measured by more than one instrument which allow to perform extensive and continuous cross-calibration analyses. In addition some of the instruments can be regarded as absolute or reference measurements for other instruments. The CAA attempts to avoid as much as possible mission-specific acronyms and concepts and tends to use more generic terms in describing the datasets and their contents in order to ease the usage of the CAA data by “non-Cluster” scientists. Currently the CAA has more 1000 users and every month more than 150 different users log in the CAA for plotting and/or downloading observations. The users download about 1 TeraByte of data every month. The CAA has separated the graphical tool from the download tool because full-resolution datasets can be visualized in many

  13. Dual Repression of the Multidrug Efflux Pump CmeABC by CosR and CmeR in Campylobacter jejuni

    PubMed Central

    Grinnage-Pulley, Tara; Mu, Yang; Dai, Lei; Zhang, Qijing

    2016-01-01

    During transmission and intestinal colonization, Campylobacter jejuni, a major foodborne human pathogen, experiences oxidative stress. CosR, a response regulator in C. jejuni, modulates the oxidative stress response and represses expression of the CmeABC multidrug efflux pump. CmeABC, a key component in resistance to toxic compounds including antimicrobials and bile salts, is also under negative regulation by CmeR, a TetR family transcriptional regulator. How CosR and CmeR interact in binding to the cmeABC promoter and how CosR senses oxidative stress are still unknown. To answer these questions, we conducted various experiments utilizing electrophoretic mobility shift assays and transcriptional fusion assays. CosR and CmeR bound independently to two separate sites of the cmeABC promoter, simultaneously repressing cmeABC expression. This dual binding of CosR and CmeR is optimal with a 17 base pair space between the two binding sites as mutations that shortened the distance between the binding sites decreased binding by CmeR and enhanced cmeABC expression. Additionally, the single cysteine residue (C218) of CosR was sensitive to oxidation, which altered the DNA-binding activity of CosR and dissociated CosR from the cmeABC promoter as determined by electrophoretic mobility shift assay. Replacement of C218 with serine rendered CosR insensitive to oxidation, suggesting a potential role of C218 in sensing oxidative stress and providing a possible mechanism for CosR-mediated response to oxidative stress. These findings reveal a dual regulatory role of CosR and CmeR in modulating cmeABC expression and suggest a potential mechanism that may explain overexpression of cmeABC in response to oxidative stress. Differential expression of cmeABC mediated by CmeR and CosR in response to different signals may facilitate adaptation of Campylobacter to various environmental conditions. PMID:27468281

  14. INITIATION AND ERUPTION PROCESS OF MAGNETIC FLUX ROPE FROM SOLAR ACTIVE REGION NOAA 11719 TO EARTH-DIRECTED CME

    SciTech Connect

    Vemareddy, P.; Zhang, J.

    2014-12-20

    An eruption event launched from the solar active region (AR) NOAA 11719 is investigated based on coronal EUV observations and photospheric magnetic field measurements obtained from the Solar Dynamic Observatory. The AR consists of a filament channel originating from a major sunspot and its south section is associated with an inverse-S sigmoidal system as observed in Atmospheric Imaging Assembly passbands. We regard the sigmoid as the main body of the flux rope (FR). There also exists a twisted flux bundle crossing over this FR. This overlying flux bundle transforms in shape similar to kink-rise evolution, which corresponds with the rise motion of the FR. The emission measure and temperature along the FR exhibits an increasing trend with its rising motion, indicating reconnection in the thinning current sheet underneath the FR. Net magnetic flux of the AR, evaluated at north and south polarities, showed decreasing behavior whereas the net current in these fluxes exhibits an increasing trend. Because the negative (positive) flux has a dominant positive (negative) current, the chirality of AR flux system is likely negative (left handed) in order to be consistent with the chirality of inverse S-sigmoidal FR. This analysis of magnetic fields of the source AR suggests that the cancelling fluxes are prime factors of the monotonous twisting of the FR system, reaching to a critical state to trigger kink instability and rise motion. This rise motion may have led to the onset of the torus instability, resulting in an Earth-directed coronal mass ejection, and the progressive reconnection in the thinning current sheet beneath the rising FR led to the M6.5 flare.

  15. The State of the Art in CME.

    ERIC Educational Resources Information Center

    Richards, Robert K.

    1983-01-01

    The author describes major trends and directions related to continuing medical education (CME). The rapid changes he observed in the state of the art in CME are presented in relation to three historical periods in the past 16 years. (SSH)

  16. Cluster of solar active regions and onset of coronal mass ejections

    NASA Astrophysics Data System (ADS)

    Wang, JingXiu; Zhang, YuZong; He, Han; Chen, AnQin; Jin, ChunLan; Zhou, GuiPing

    2015-09-01

    Abstract round-the-clock solar observations with full-disk coverage of vector magnetograms and multi-wavelength images demonstrate that solar active regions (ARs) are ultimately connected with magnetic field. Often two or more ARs are clustered, creating a favorable magnetic environment for the onset of coronal mass ejections (CMEs). In this work, we describe a new type of magnetic complex: cluster of solar ARs. An AR cluster is referred to as the close connection of two or more ARs which are located in nearly the same latitude and a narrow span of longitude. We illustrate three examples of AR clusters, each of which has two ARs connected and formed a common dome of magnetic flux system. They are clusters of NOAA (i.e., National Oceanic and Atmospheric Administration) ARs 11226 & 11227, 11429 & 11430, and 11525 & 11524. In these AR clusters, CME initiations were often tied to the instability of the magnetic structures connecting two partner ARs, in the form of inter-connecting loops and/or channeling filaments between the two ARs. We show the evidence that, at least, some of the flare/CMEs in an AR cluster are not a phenomenon of a single AR, but the result of magnetic interaction in the whole AR cluster. The observations shed new light on understanding the mechanism(s) of solar activity. Instead of the simple bipolar topology as suggested by the so-called standard flare model, a multi-bipolar magnetic topology is more common to host the violent solar activity in solar atmosphere.

  17. Reflections on CME Congress 2012

    ERIC Educational Resources Information Center

    Knox, Alan B.

    2013-01-01

    This commentary reflects the author's impressions of Continuing Medical Education (CME) Congress 2012, a provocative international conference on professional development and quality improvement in the health professions that took place in Toronto, Ontario, last spring. The sessions he attended and conversations he had with other attendees were…

  18. The Flare-CME Connection

    NASA Astrophysics Data System (ADS)

    Raftery, Claire; Gallagher, P. T.; Lin, C.

    2009-05-01

    The connection between flares and CMEs has long been hypothesized and modelled. However, a full understanding of the processes at work remains ambiguous. A detailed study of the kinematical evolution of a CME was conducted using instruments on STEREO. Flare parameters, such as the motion of soft X-ray sources, imaged using RHESSI, and emission measure and plasma temperature measured from Mercury MESSENGER are presented in conjunction with the CME data to explain the evolution of the entire system. These results are then compared to a number of theoretical models to determine which of the many hypotheses are most probable for this event. CLR is supported by an SPD studentship and the ESA/Prodex grant administered by Enterprise Ireland.

  19. Rethinking CME: an imperative for academic medicine and faculty development.

    PubMed

    Davis, David A; Prescott, John; Fordis, C Michael; Greenberg, Stephen B; Dewey, Charlene M; Brigham, Timothy; Lieberman, Steve A; Rockhold, Robin W; Lieff, Susan J; Tenner, Thomas E

    2011-04-01

    To help address the clinical care gap, a working group discussed the future of faculty development in academic medicine, explored problems within the large, current enterprise devoted to continuing medical education (CME), and described four domains core to its revitalization and reformation. These domains are (1) preparing and supporting an engaged clinician-learner, (2) improving the quality of knowledge or evidence shared, (3) enhancing the means by which to disseminate and implement that knowledge and evidence, and (4) reforming the patient, health care, and regulatory systems in and for which the process of CME exists. Reshaping these domains requires the consideration of a more seamless, evidence-based, and patient-oriented continuum of medical education. Revitalizing CME also requires the full engagement of the academic medical community and its faculty. To achieve the goal of creating a new, more effective, seamless process of CME, the working group recommended an active faculty development process to develop strong clinician-learners, strong involvement of academic health center leaders, the development of an educational home for clinician-learners, and a meaningful national conversation on the subject of CME. PMID:21346497

  20. Italy. [CME Country Reports].

    ERIC Educational Resources Information Center

    Council of Europe, Strasbourg (France). Documentation Center for Education in Europe.

    Ever since 1946, increased emigration in Italy has been paralleled by a slow but steady increase in educational activity. In 1971, Law No. 153 was adopted which provides for special educational arrangements to be made for migrant workers and their spouses adopted by the Italian Government are based on the need for Italian children to: (1) be…

  1. Controlling Quality in CME/CPD by Measuring and Illuminating Bias

    ERIC Educational Resources Information Center

    Dixon, David; Takhar, Jatinder; Macnab, Jennifer; Eadie, Jason; Lockyer, Jocelyn; Stenerson, Heather; Francois, Jose; Bell, Mary; Monette, Celine; Campbell, Craig; Marlow, Bernie

    2011-01-01

    Introduction: There has been a surge of interest in the area of bias in industry-supported continuing medical education/continuing professional development (CME/CPD) activities. In 2007, we published our first study on measuring bias in CME, demonstrating that our assessment tool was valid and reliable. In light of the increasing interest in this…

  2. The deflection of 2008 December 12 CME

    NASA Astrophysics Data System (ADS)

    Shen, C.; Wang, Y.; Liu, J.; Ye, P.; Wang, S.

    2010-12-01

    The deflection of CME, which would significant influence the CME's geoeffectiveness, is an important topic of space weather study. In this work, the deflection of 2008 December 12 CME during it propagated from the Sun to Earth will be detailed studied based on the combination of remote and in situ observations. First, the 3-dimensions parameters reconstructed by Graduated Cylindrical Shell (GCS) model based on the STEREO observations were used to study the propagation direction evolution of this CME during it propagated in near solar space. During this phase, this CME deflect from high latitude region to equator in meridian plane but propagated almost along the longitude of W7 in ecliptic plane. Further, whether this CME deflected during it propagated in interplanetary space has also been checked. Based on the remote observations, if this CME propagated radially during it propagated in interplanetary space, it may arrived the Earth and then hit the STEREO A rather than hit STEREO B. But, the in situ observations show contrary results that this CME arrived the Earth and hit the STEREO B but missed STEREO A. This result show direct evidence that this CME deflected to east in ecliptic plane during it propagated in interplanetary space. The kinematic deflection model developed by Wang et. al (2004) has been applied on this CME. The calculation results of this model correspond well with the observational results.

  3. Propagation of the 7 January 2014 CME and Resulting Geomagnetic Non-event

    NASA Astrophysics Data System (ADS)

    Mays, M. L.; Thompson, B. J.; Jian, L. K.; Colaninno, R. C.; Odstrcil, D.; Möstl, C.; Temmer, M.; Savani, N. P.; Collinson, G.; Taktakishvili, A.; MacNeice, P. J.; Zheng, Y.

    2015-10-01

    On 2014 January 7 an X1.2 flare and coronal mass ejection (CME) with a radial speed ≈2500 km s-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 KP 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.

  4. Propagation of the 7 January 2014 CME and Resulting Geomagnetic Non-event

    NASA Astrophysics Data System (ADS)

    Mays, M. L.; Thompson, B. J.; Jian, L. K.; Colaninno, R. C.; Odstrcil, D.; Möstl, C.; Temmer, M.; Savani, N. P.; Collinson, G.; Taktakishvili, A.; MacNeice, P. J.; Zheng, Y.

    2015-10-01

    On 2014 January 7 an X1.2 flare and coronal mass ejection (CME) with a radial speed ≈2500 km s‑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 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.

  5. The energy sources of CME acceleration

    NASA Astrophysics Data System (ADS)

    Allawi, H.; Pohjolainen, S.

    2012-11-01

    We investigate the possibility that during the fast acceleration phase of a coronal mass ejection (CME), a freely propagating shock wave could be launched. We test this hypothesis by calculating the speeds of blast waves by using the Taylor-Sedov equation in changing density solar atmosphere, and compare these speeds with the radio type II burst speeds during the CME event on 17 February 2000. The matching speeds and the realistic value of the blast wave energy, 10^{24} J, lead us to suggest that the CME acceleration phase may involve shocks separating from the initial CME driver.

  6. Egocentric daily activity recognition via multitask clustering.

    PubMed

    Yan, Yan; Ricci, Elisa; Liu, Gaowen; Sebe, Nicu

    2015-10-01

    Recognizing human activities from videos is a fundamental research problem in computer vision. Recently, there has been a growing interest in analyzing human behavior from data collected with wearable cameras. First-person cameras continuously record several hours of their wearers' life. To cope with this vast amount of unlabeled and heterogeneous data, novel algorithmic solutions are required. In this paper, we propose a multitask clustering framework for activity of daily living analysis from visual data gathered from wearable cameras. Our intuition is that, even if the data are not annotated, it is possible to exploit the fact that the tasks of recognizing everyday activities of multiple individuals are related, since typically people perform the same actions in similar environments, e.g., people working in an office often read and write documents). In our framework, rather than clustering data from different users separately, we propose to look for clustering partitions which are coherent among related tasks. In particular, two novel multitask clustering algorithms, derived from a common optimization problem, are introduced. Our experimental evaluation, conducted both on synthetic data and on publicly available first-person vision data sets, shows that the proposed approach outperforms several single-task and multitask learning methods. PMID:26067371

  7. CME Ensemble Forecasting - A Primer

    NASA Astrophysics Data System (ADS)

    Pizzo, V. J.; de Koning, C. A.; Cash, M. D.; Millward, G. H.; Biesecker, D. A.; Codrescu, M.; Puga, L.; Odstrcil, D.

    2014-12-01

    SWPC has been evaluating various approaches for ensemble forecasting of Earth-directed CMEs. We have developed the software infrastructure needed to support broad-ranging CME ensemble modeling, including composing, interpreting, and making intelligent use of ensemble simulations. The first step is to determine whether the physics of the interplanetary propagation of CMEs is better described as chaotic (like terrestrial weather) or deterministic (as in tsunami propagation). This is important, since different ensemble strategies are to be pursued under the two scenarios. We present the findings of a comprehensive study of CME ensembles in uniform and structured backgrounds that reveals systematic relationships between input cone parameters and ambient flow states and resulting transit times and velocity/density amplitudes at Earth. These results clearly indicate that the propagation of single CMEs to 1 AU is a deterministic process. Thus, the accuracy with which one can forecast the gross properties (such as arrival time) of CMEs at 1 AU is determined primarily by the accuracy of the inputs. This is no tautology - it means specifically that efforts to improve forecast accuracy should focus upon obtaining better inputs, as opposed to developing better propagation models. In a companion paper (deKoning et al., this conference), we compare in situ solar wind data with forecast events in the SWPC operational archive to show how the qualitative and quantitative findings presented here are entirely consistent with the observations and may lead to improved forecasts of arrival time at Earth.

  8. Objective CME detection over the solar cycle

    NASA Astrophysics Data System (ADS)

    Robbrecht, E.; Berghmans, D.

    We have developed a software package for 'Computer Aided CME Tracking' (CACTus), that autonomously detects CMEs in image sequences from LASCO. The crux of the CACTus software is the detection of CMEs as bright ridges in [height, time] maps using the Hough transform. The output is a list of events, similar to the classic catalogs, with principle angle, angular width and velocity estimation for each CME. In contrast to catalogs assembled by human operators, these CME detections by software can be faster and possibly also more objective, as the detection criterion is written explicitly in a program. Especially on the timescale of a solar cycle, it is questionnable whether human, visual CME detection is stable, as the operator gains experience or personnel is replaced. In this paper we overview the latest improvements of CACTUS and validate its performance by comparing the CACTus output with the classical, visually assembled CME catalogs. Discrepancies between the classical catalogs and the CACTUS catalogs are discussed. Such discrepancies highlight not only the performance of CACTUS but also the caveats of the classical catalogs. Indeed, CACTUS sometimes finds CMEs that are not listed in the catalogs or interpreted differently (eg halo CME or not). It is important to know these caveats when using the CME catalogs as input for statistical CME studies over the solar cycle. The near realtime output of the software is available on the web(http://sidc.oma.be/cactus) and is updated daily.

  9. The Solar Stormwatch CME catalogue.

    NASA Astrophysics Data System (ADS)

    Barnard, Luke

    2015-04-01

    Since the launch of the twin STEREO satellites in late 2006, the Heliospheric Imagers have been used, with good results, in tracking transients of solar origin, such as Coronal Mass Ejections (CMEs), out through the inner heliosphere. A frequently used approach is to build a "J-Map", in which multiple elongation profiles along a constant position angle are stacked in time, building an image in which radially propagating transients form curved tracks in the J-Map. From this the time-elongation profile of a solar transient can be manually identified. This is a time consuming and laborious process, and the results are subjective, depending on the skill and expertise of the investigator. With the Heliospheric Imager data it is possible to follow CMEs from the outer limits of the solar corona all the way to 1AU. Solar Stormwatch is a citizen science project that employs the power of thousands of volunteers to both identify and track CMEs in the Heliospheric Imager data. The CMEs identified by Solar Stormwatch are tracked many times by multiple users and this allows the calculation of consensus time-elongation profiles for each event and also provides an estimate of the error in the consensus profile. Therefore this system does not suffer from the potential subjectivity of individual researchers identifying and tracking CMEs. In this sense, the Solar Stormwatch system can be thought of as providing a middle ground between manually identified CME catalogues, such as the CDAW list, and CME catalogues generated through fully automated algorithms, such as CACtus and ARTEMIS etc. We provide a summary of the reduction of the Solar Stormwatch data into a catalogue of CMEs observed by STEREO-A and STEREO-B through the deep minimum of solar cycle 23 and review some key statistical properties of these CMEs. Through some case studies of the propagation of CMEs out into the inner heliosphere we argue that the Solar Stormwatch CME catalogue, which publishes the time

  10. Reevaluating Active Galactic Nuclei in Rich Clusters

    NASA Astrophysics Data System (ADS)

    Way, M. J.; Flores, R.; Quintana, H.

    1999-06-01

    We have selected 42 candidate Active Galactic Nuclei in 19 Rich Abell Clusters. The candidates were selected using the criteria of Dressler, Thompson & Shectman (1985; DTS) in their analysis of the statistics of 22 AGN in 14 rich cluster fields, which are based on the equivalent width of [OII]3727Å, H β, and [OIII]5007Å emission. These AGN are then separated from HII galaxies in the manner developed by Veilleux & Osterbrock (1987; VO) using the additional information provided by Hα and [NII]6583Å or Hα and [SII]6716 + 6731Å emission, in order to test the reliability of the selection criteria used by DTS. Our sample is very comparable to that of DTS before we discriminate AGN from HII galaxies, and would lead to similar conclusions. However, we find that their method inevitably mixes HII galaxies with AGN. Over the years many authors have attempted to quantify the relative fraction of cluster to field AGN since the study of DTS (Hill & Oegerle 1993; Biviano et al. 1997) and have reached similar conclusions, but using criteria similar to that of DTS to select AGN (or using the [OIII]5007Å/H β flux ratio test that also mixes HII galaxies with AGN).

  11. CME Prediction from Line-of-Sight Magnetogram

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Gary, G. A.

    2003-01-01

    We have previously shown for bipolar active regions that measures of active-region nonpotentiality from vector magnetograms are correlated with active-region CME productivity. We have now obtained a measure from line-of-sight magnetograms that is well correlated both with our measures of active-region nonpotentiality from vector magnetograms and with active-region CME productivity. The measure is the length of strong-gradient main neutral line (L(sub G)). This is the length of the bipolar region's main neutral line on which the potential transverse field is greater than 150G, and the gradient in the line-of-sight field is greater than 50G/Mm. From the sample of 17 MSFC magnetograms of 12 basically bipolar active regions used in our previous paper, we find that L(sub G) is strongly correlated with one of our vector-magnetogram measures of nonpotentiality, the length of strong-gradient main neutral line L(sub SS) (99.7%). We also find that L(sub G) is as strongly correlated with CME productivity (99.7%) as is L(sub SS). Being obtainable from line-of-sight magnetograms, L(sub G) makes the much larger data set of line-of-sight magnetograms (i.e. from SOHO/MDI and Kitt Peak) available for CME prediction study. This is especially important for evolutionary studies, with SOHO/MDI having no daylight, cloudy weather, or atmospheric seeing problems. This work was supported by funding from NSF's division of Atmospheric Sciences (Space Weather and Shine Programs) and by NASA's office of Space Science (Living with a Star program Solar and Heliospheric Physics Supporting Research and Technology program).

  12. Ensemble Modeling of CME Propagation and Geoeffectiveness

    NASA Astrophysics Data System (ADS)

    Mays, M. Leila; Taktakishvili, Aleksandre; Pulkkinen, Antti; MacNeice, Peter; Rastätter, Lutz; Odstrcil, Dusan; Jian, Lan; Richardson, Ian

    2015-04-01

    Ensemble modeling of coronal mass ejections (CMEs) provides a probabilistic forecast of CME arrival time which includes an estimation of arrival time uncertainty from the spread and distribution of predictions and forecast confidence in the likelihood of CME arrival. The real-time ensemble modeling of CME propagation uses the Wang-Sheeley-Arge (WSA)-ENLIL+Cone model installed at the {Community Coordinated Modeling Center} (CCMC) and executed in real-time at the CCMC/{Space Weather Research Center}. The current implementation of this ensemble modeling method evaluates the sensitivity of WSA-ENLIL+Cone model simulations of CME propagation to initial CME parameters. We discuss the results of real-time ensemble simulations for a total of 35 CME events which occurred between January 2013 - July 2014. For the 17 events where the CME was predicted to arrive at Earth, the mean absolute arrival time prediction error was 12.3 hours, which is comparable to the errors reported in other studies. For predictions of CME arrival at Earth the correct rejection rate is 62%, the false-alarm rate is 38%, the correct alarm ratio is 77%, and false alarm ratio is 23%. The arrival time was within the range of the ensemble arrival predictions for 8 out of 17 events. The Brier Score for CME arrival predictions is 0.15 (where a score of 0 on a range of 0 to 1 is a perfect forecast), which indicates that on average, the predicted probability, or likelihood, of CME arrival is fairly accurate. The reliability of ensemble CME arrival predictions is heavily dependent on the initial distribution of CME input parameters (e.g. speed, direction, and width), particularly the median and spread. Preliminary analysis of the probabilistic forecasts suggests undervariability, indicating that these ensembles do not sample a wide enough spread in CME input parameters. Prediction errors can also arise from ambient model parameters, the accuracy of the solar wind background derived from coronal maps, or other

  13. December 2008 CME as Viewed by Spacecraft

    NASA Video Gallery

    Newly reprocessed images from NASA's STEREO-A spacecraft, allow scientists to trace the anatomy of the December 2008 CME as it moves and changes on its journey from the Sun to the Earth, identify t...

  14. Spectroscopic Active Galaxies and Clusters Explorer

    NASA Astrophysics Data System (ADS)

    Ferrari, L.; Bagliani, D.; Bardi, A.; Battistelli, E.; Birkinshaw, M.; Colafrancesco, S.; Conte, A.; Debernardis, P.; Degregori, S.; Depetris, M.; de Zotti, G.; Donati, A.; Franceschini, A.; Gatti, F.; Gervasi, M.; Gonzalez-Nuevo, J.; Lamagna, L.; Luzzi, G.; Maiolino, M.; Marchegiani, P.; Mariani, A.; Masi, S.; Massardi, M.; Mauskopf, P.; Nati, L.; Nati, F.; Natoli, P.; Piacentini, F.; Polenta, G.; Porciani, M.; Savini, G.; Schillaci, A.; Spinelli, S.; Tartari, A.; Tavanti, M.; Tortora, A.; Vaccari, M.; Vaccarone, R.; Zannoni, M.

    2009-12-01

    We present a concept for the payload SAGACE, the Spectroscopic Active Galaxies And Cluster Explorer, devoted to study the evolution of Universe structures using different observables, all of them in the mm/submm wavelength. The SAGACE payload is made of a passively cooled 3 m telescope, a cryogenic Fourier Transform Spectrometer (FTS) and detector arrays to be operated at 0.3 K by a 3He fridge. The detectors are Ti/Au Transition Edge Sensor (TES) bolometers with a NEP<10-17 W/Hz12. A phase-A study has been recently completed for this experiment, in the framework of the call for small missions of the Italian Space Agency.

  15. The Great "Non-Event" of 7 January 2014: Challenges in CME Arrival Time and Geomagnetic Storm Strength Prediction

    NASA Astrophysics Data System (ADS)

    Mays, M. L.; Thompson, B. J.; Jian, L.; Evans, R. M.; Savani, N.; Odstrcil, D.; Nieves-Chinchilla, T.; Richardson, I. G.

    2014-12-01

    We present a case study of the 7 January 2014 event in order to highlight current challenges in space weather forecasting of CME arrival time and geomagnetic storm strength. On 7 January 2014 an X1.2 flare and CME with a radial speed ~2400 km/s was observed from active region 11943. The flaring region was only ten degrees southwest of disk center with extensive dimming south of the active region and preliminary analysis indicated a fairly rapid arrival at Earth (~36 hours). Of the eleven forecasting groups world-wide who participated in CCMC's Space Weather Scoreboard (http://kauai.ccmc.gsfc.nasa.gov/SWScoreBoard), nine predicted early arrivals and six predicted dramatic geomagnetic storm impacts (Kp predictions ranged from 6 to 9). However, the CME only had a glancing blow arrival at Earth - Kp did not rise above 3 and there was no geomagnetic storm. What happened? One idea is that the large coronal hole to the northeast of the active region could have deflected the CME. This coronal hole produced a high speed stream near Earth reaching an uncommon speed of 900 km/s four days after the observed CME arrival. However, no clear CME deflection was observed in the outer coronagraph fields of view (~5-20Rs) where CME measurements are derived to initiate models, therefore deflection seems unlikely. Another idea is the effect of the CME flux rope orientation with respect to Earth orbit. We show that using elliptical major and minor axis widths obtained by GCS fitting for the initial CME parameters in ENLIL would have improved the forecast to better reflect the observed glancing blow in-situ signature. We also explore the WSA-ENLIL+Cone simulations, the background solar wind solution, and compare with the observed CME arrival at Venus (from Venus Express) and Earth.

  16. ForeCAT: Using CME Deflections to Constrain their Mass and the Drag

    NASA Astrophysics Data System (ADS)

    Kay, C.; dos Santos, L. F. G.; Opher, M.

    2014-12-01

    Observations show that CMEs can deflect from a purely radial trajectory yet no consensus exists as to the cause of these deflections. The majority of the deflection motion occurs in the corona at distances where the magnetic energy dominates. Accordingly, many theories attribute the CME deflection to magnetic forces. In Kay et al. (2013) we presented ForeCAT, a model for CME deflections based on the magnetic forces (magnetic tension and magnetic pressure gradients). Kay et al. (2014) introduced an improved three-dimensional version of ForeCAT. Here we study the 2008 December 12 CME which occurred during solar minimum of Solar Cycle 24 (Byrne et al 2010, Gui et al. 2011, Liu et al 2010a,b). This CME erupted from high latitudes, and, despite the weak background magnetic field, deflected to the ecliptic, impacting Earth. From the observations, we are able to constrain all of the ForeCAT input parameters except for the CME mass and the drag coefficient that affects the CME motion. The reduced chi-square best fit to the observations constrains the CME mass range to 3e14 to 7e14 g and the drag coefficient range to 1.9 to 2.4. We explore the effects of a different magnetic background which decreases less rapidly than our standard Potential Field Source Surface (PFSS) model, as type II radio bursts suggest that the PFSS magnetic field decays too rapidly above active regions. For the case of the filament eruption of 2008 December 12 we find that the quiet sun coronal magnetic field should behave similar to the PFSS model. Finally, we present our current work exploring the case of the 2008 April 9 CME.

  17. A Radio Burst and Its Associated CME on March 17, 2002

    NASA Astrophysics Data System (ADS)

    Yan, Y.; Pick, M.; Wang, M.; Krucker, S.; Vourlidas, A.

    2006-12-01

    In this study, we present a detailed analysis, based on multiwavelength observations and magnetic field extrapolation, of a radio and X-ray event observed on March 17, 2002. This event was accompanied by a Coronal Mass Ejection (CME) observed by the Large-Angle Spectrometric Coronagraph (LASCO) aboard SOHO. During the main event, the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) mission observed a hard X-ray emission correlated in time with the development of a type III burst group. The CME development, the hard X-ray emission, and the type III burst group appear to be closely associated. The multifrequency Nançay Radioheliograph (NRH) shows that the type III bursts are produced at a distance from the active region that progressively increases with time. Their emitting sources are distributed along the western edge of the CME. We conclude the type III electron beams propagate in the interface region between the ascending CME and the neighboring open field lines. Due to the development of the CME, this region becomes progressively highly compressed. By measuring, at each frequency, the shift versus time of the type III positions, we estimate that the electron density in this compression region increased roughly by a factor of 10 over a few minutes. Another signature of this compression region is a narrow white light feature interpreted as a coronal shock driven by the CME lateral expansion.

  18. Automatic CME Detection from Coronagraph Image Pairs

    NASA Astrophysics Data System (ADS)

    Liewer, P. C.; Dejong, E. M.; Hall, J. R.; Lorre, J. J.

    2005-12-01

    We have developed a technique for the automatic detection of coronal mass ejections using two sequential coronagraph images. The technique is based on tracking arc-like features from one image to the next; the feature's velocity is also determined. The method has been developed and tested using LASCO C2 and C3 data. The goal of this work is to develop an automatic CME detection algorithm that can be used on board the STEREO spacecraft to preferentially downlink data containing CMEs from an onboard "rotating" data buffer. Results for this detection technique compare very favorably with CMEs identified in the LASCO CME catalog (http://cdaw.gsfc.nasa.gov/CME_list/). For the periods when results were compared, no time periods with significant CMEs were missed using the automatic technique.

  19. HELCATS Prediction of Planetary CME arrival times

    NASA Astrophysics Data System (ADS)

    Boakes, Peter; Moestl, Christian; Davies, Jackie; Harrison, Richard; Byrne, Jason; Barnes, David; Isavnin, Alexey; Kilpua, Emilia; Rollett, Tanja

    2015-04-01

    We present the first results of CME arrival time prediction at different planetary locations and their comparison to the in situ data within the HELCATS project. The EU FP7 HELCATS (Heliospheric Cataloguing, Analysis & Techniques Service) is a European effort to consolidate the exploitation of the maturing field of heliospheric imaging. HELCATS aims to catalogue solar wind transients, observed by the NASA STEREO Heliospheric Imager (HI) instruments, and validate different methods for the determination of their kinematic properties. This validation includes comparison with arrivals at Earth, and elsewhere in the heliosphere, as well as onsets at the Sun (http://www.helcats-fp7.eu/). A preliminary catalogue of manually identified CMEs, with over 1000 separate events, has been created from observations made by the STEREO/HI instruments covering the years 2007-2013. Initial speeds and directions of each CME have been derived through fitting the time elongation profile to the state of the art Self-Similar Expansion Fitting (SSEF) geometric technique (Davies et al., 2012). The technique assumes that, in the plane corresponding to the position angle of interest, CMEs can be modelled as circles subtending a fixed angular width to Sun-center and propagating anti-sunward in a fixed direction at a constant speed (we use an angular width of 30 degrees in our initial results). The model has advantages over previous geometric models (e.g. harmonic mean or fixed phi) as it allows one to predict whether a CME will 'hit' a specific heliospheric location, as well as to what degree (e.g. direct assault or glancing blow). We use correction formulae (Möstl and Davies, 2013) to convert CME speeds, direction and launch time to speed and arrival time at any in situ location. From the preliminary CME dataset, we derive arrival times for over 400 Earth-directed CMEs, and for over 100 Mercury-, Venus-, Mars- and Saturn-directed CMEs predicted to impact each planet. We present statistics of

  20. Space Weather Model of July 22-23, 2012 CME

    NASA Video Gallery

    NASA's Space Weather Research Center modeled the July 23, 2012 CME using a modeling program called ENLIL. The CME can be seen to expand dramatically as it travels through space. By comparing how we...

  1. If formal CME is ineffective, why do physicians still participate?

    PubMed

    McLeod, P J; McLeod, A H

    2004-03-01

    Formal or traditional CME can be criticized because organizers often ignore adult learning principles when designing courses. Critics also suggest that formal CME courses have limited impact on attendees' behaviors and practices. The authors agree that attention must be paid to pedagogic principles to assure success of educational courses, but feel that the extant negative evidence related to the impact of formal CME is narrow in scope and of inadequate strength to seriously damn formal approaches. Survey responses were received from 853 practicing physicians who say they still regularly attend formal CME courses. They are motivated to attend to satisfy specific professional needs and for personal reasons. Formal CME is still popular despite what its critics say. The authors are convinced that attention to physicians' perceived needs, effective use of social marketing strategies, and adherence to adult learning principles can assure successful delivery of CME and that formal CME is a useful complement to physician-driven informal CME. PMID:15203529

  2. STEREO Captures Fastest CME to Date

    NASA Video Gallery

    This movie shows a coronal mass ejection (CME) on the sun from July 22, 2012 at 10:00 PM EDT until 2 AM on July 23 as captured by NASA's Solar TErrestrial RElations Observatory-Ahead (STEREO-A). Be...

  3. Directed Self-Assembly Pathways of Active Colloidal Clusters.

    PubMed

    Zhang, Jie; Yan, Jing; Granick, Steve

    2016-04-18

    Despite the mounting interest in synthetic active particles, too little is known about their assembly into higher-order clusters. Here, mixing bare silica particles with Janus particles that are self-propelled in electric fields, we assemble rotating chiral clusters of various sorts, their structures consisting of active particles wrapped around central "hub" particles. These clusters self-assemble from the competition between standard energetic interactions and the need to be stable as the clusters rotate when the energy source is turned on, and fall apart when the energy input is off. This allows one to guide the formation of intended clusters, as the final structure depends notably on the sequence of steps in which the clusters form. PMID:27010594

  4. The Growth, Characteristics, and Future of Online CME

    ERIC Educational Resources Information Center

    Harris, John M., Jr.; Sklar, Bernard M.; Amend, Robert W.; Novalis-Marine, Cheryl

    2010-01-01

    Introduction: Physician use of online continuing medical education (CME) is growing, but there are conflicting data on the uptake of online CME and few details on this market. Methods: Analyses of 11 years of data from the Accreditation Council for Continuing Medical Education (ACCME) and a survey of 272 publicly available CME Web sites. …

  5. Sharing Collaborative Designs of Tobacco Cessation Performance Improvement CME Projects

    ERIC Educational Resources Information Center

    Mullikin, Elizabeth A.; Ales, Mary W.; Cho, Jane; Nelson, Teena M.; Rodrigues, Shelly B.; Speight, Mike

    2011-01-01

    Introduction: Performance Improvement Continuing Medical Education (PI CME) provides an important opportunity for CME providers to combine educational and quality health care improvement methodologies. Very few CME providers take on the challenges of planning this type of intervention because it is still a new practice and there are limited…

  6. Learning to Collaborate: A Case Study of Performance Improvement CME

    ERIC Educational Resources Information Center

    Shershneva, Marianna B.; Mullikin, Elizabeth A.; Loose, Anne-Sophie; Olson, Curtis A.

    2008-01-01

    Introduction: Performance Improvement Continuing Medical Education (PI CME) is a mechanism for joining quality improvement (QI) in health care to continuing medical education (CME) systems together. Although QI practices and CME approaches have been recognized for years, what emerges from their integration is largely unfamiliar, because it…

  7. CME and Change in Practice: An Alternative Perspective.

    ERIC Educational Resources Information Center

    Wergin, Jon F.; And Others

    1988-01-01

    Results of a study by the American College of Cardiology revealed that continuing medical education (CME) courses contain relatively little information that is new to the audience, that other influences on practice interact with CME content, and that change attributable to CME is subtle and often delayed. (JOW)

  8. Probability of CME Impact on Exoplanets Orbiting M Dwarfs and Solar-like Stars

    NASA Astrophysics Data System (ADS)

    Kay, C.; Opher, M.; Kornbleuth, M.

    2016-08-01

    Solar coronal mass ejections (CMEs) produce adverse space weather effects at Earth. Planets in the close habitable zone of magnetically active M dwarfs may experience more extreme space weather than at Earth, including frequent CME impacts leading to atmospheric erosion and leaving the surface exposed to extreme flare activity. Similar erosion may occur for hot Jupiters with close orbits around solar-like stars. We have developed a model, Forecasting a CME's Altered Trajectory (ForeCAT), which predicts a CME's deflection. We adapt ForeCAT to simulate CME deflections for the mid-type M dwarf V374 Peg and hot Jupiters with solar-type hosts. V374 Peg's strong magnetic fields can trap CMEs at the M dwarfs's Astrospheric Current Sheet, that is, the location of the minimum in the background magnetic field. Solar-type CMEs behave similarly, but have much smaller deflections and do not become trapped at the Astrospheric Current Sheet. The probability of planetary impact decreases with increasing inclination of the planetary orbit with respect to the Astrospheric Current Sheet: 0.5–5 CME impacts per day for M dwarf exoplanets, 0.05–0.5 CME impacts per day for solar-type hot Jupiters. We determine the minimum planetary magnetic field necessary to shield a planet's atmosphere from CME impacts. M dwarf exoplanets require values between tens and hundreds of Gauss. Hot Jupiters around a solar-type star, however, require a more reasonable <30 G. These values exceed the magnitude required to shield a planet from the stellar wind, suggesting that CMEs may be the key driver of atmospheric losses.

  9. CHARACTERISTICS OF KINEMATICS OF A CORONAL MASS EJECTION DURING THE 2010 AUGUST 1 CME-CME INTERACTION EVENT

    SciTech Connect

    Temmer, Manuela; Rollett, Tanja; Bein, Bianca; Moestl, Christian; Veronig, Astrid M.; Flor, Olga; Vrsnak, Bojan; Zic, Tomislav; De Koning, Curt A.; Liu, Ying; Bosman, Eckhard; Davies, Jackie A.; Bothmer, Volker; Harrison, Richard; Nitta, Nariaki; Bisi, Mario; Eastwood, Jonathan; Forsyth, Robert; Odstrcil, Dusan

    2012-04-10

    We study the interaction of two successive coronal mass ejections (CMEs) during the 2010 August 1 events using STEREO/SECCHI COR and heliospheric imager (HI) data. We obtain the direction of motion for both CMEs by applying several independent reconstruction methods and find that the CMEs head in similar directions. This provides evidence that a full interaction takes place between the two CMEs that can be observed in the HI1 field of view. The full de-projected kinematics of the faster CME from Sun to Earth is derived by combining remote observations with in situ measurements of the CME at 1 AU. The speed profile of the faster CME (CME2; {approx}1200 km s{sup -1}) shows a strong deceleration over the distance range at which it reaches the slower, preceding CME (CME1; {approx}700 km s{sup -1}). By applying a drag-based model we are able to reproduce the kinematical profile of CME2, suggesting that CME1 represents a magnetohydrodynamic obstacle for CME2 and that, after the interaction, the merged entity propagates as a single structure in an ambient flow of speed and density typical for quiet solar wind conditions. Observational facts show that magnetic forces may contribute to the enhanced deceleration of CME2. We speculate that the increase in magnetic tension and pressure, when CME2 bends and compresses the magnetic field lines of CME1, increases the efficiency of drag.

  10. Characteristics of Kinematics of a Coronal Mass Ejection During the 2010 August 1 CME-CME Interaction Event

    NASA Technical Reports Server (NTRS)

    Temmer, Manuela; Vrsnak, Bojan; Rollett, Tanja; Bein, Bianca; de Koning, Curt A.; Liu, Ying; Bosman, Eckhard; Davies, Jackie A.; Mostl, Christian; Zic, Tomislav; Veronig, Astrid M.; Bothmer, Volker; Harrison, Richard; Nitta, Nariaki; Bisi, Mario; Flor, Olga; Eastwood, Jonathan; Odstrcil, Dusan; Forsyth, Robert

    2012-01-01

    We study the interaction of two successive coronal mass ejections (CMEs) during the 2010 August 1 events using STEREO/SECCHI COR and HI data. We obtain the direction of motion for both CMEs by applying several independent reconstruction methods and find that the CMEs head in similar directions. This provides evidence that a full interaction takes place between the two CMEs that can be observed in the HI1 field-of-view. The full de-projected kinematics of the faster CME from Sun to Earth is derived by combining remote observations with in situ measurements of the CME at 1 AU. The speed profile of the faster CME (CME2; (is) approximately 1200 km s-1) shows a strong deceleration over the distance range at which it reaches the slower, preceding CME (CME1; (is) approximately 700 km s-1). By applying a drag-based model we are able to reproduce the kinematical profile of CME2 suggesting that CME1 represents a magnetohydrodynamic obstacle for CME2 and that, after the interaction, the merged entity propagates as a single structure in an ambient flow of speed and density typical for quiet solar wind conditions. Observational facts show that magnetic forces may contribute to the enhanced deceleration of CME2. We speculate that the increase in magnetic tension and pressure, when CME2 bends and compresses the magnetic field lines of CME1, increases the efficiency of drag.

  11. Numerical Simulation of a "Stealth" CME: Why Slow and Simple is Not Mysterious

    NASA Astrophysics Data System (ADS)

    Lynch, B. J.; Li, Y.; Antiochos, S. K.; DeVore, C. R.; Luhmann, J. G.; Fisher, G. H.

    2011-12-01

    The stereoscopic viewing and improvements in coronagraph observations by STEREO/SECCHI and low corona EUV and X-ray observations at multiple wavelengths by STEREO, Hinode, and SDO -- combined with this solar minimum's exceptionally low activity -- have given rise to the community's interest in so-called "stealth" CMEs. A "stealth" CME is one in which there are almost no low coronal signatures of the CME eruption but often a very well resolved slow, flux-rope like eruption seen in the coronagraph data. The fact that the in situ observations of "stealth" CMEs have shown many of the signatures of magnetic clouds (including the interplanetary flux rope structure) poses the question, "Just how different these events are from normal CMEs?" We present a 3D numerical MHD simulation of the 2008 Jun 2 gradual streamer blowout CME which had virtually no identifiable low coronal signatures. We energize the field by simple footpoint shearing along the source region's polarity inversion line (PIL) and model the background solar wind structure using an ~2MK isothermal wind and a low-order PFSS representation of the CR2070 synoptic magnetogram. Our results will show that the CME "initiation" is obtained by slowly disrupting the quasi-steady-state configuration of the helmet streamer, resulting in the standard eruptive flare picture (albeit, on a large scale) that ejects the sheared fields and lowers the magnetic energy stored in filament channel. We obtain a relatively slow CME eruption and argue that these "stealth" CMEs are no different than the standard quasi-2D picture but are simply at the low end of the CME energy distribution. We will show preliminary comparisons between the simulation results and the coronagraph observations of the low coronal evolution of the CME.

  12. Radio signatures of CME-streamer interaction

    NASA Astrophysics Data System (ADS)

    CHEN, Y.; Feng, S.; Kong, X.; Li, G.; Song, H.

    2011-12-01

    Recent observational finding of streamer waves using the LASCO white light data presents us interesting physical consequence of CME-streamer interactions [1, 2, 3]. CME-streamer interactions can also manifest themselves in the Type-II-related radio dynamic spectra as recorded by the ground-based or space-borne instruments. A large body of studies exists revealing the possible roles of pre-existing helmet streamers in the radio emission during a solar eruption. In this presentation, we will summary our efforts in classifying the roles of streamers affecting Type-II radio emissions. Generally speaking, there exist two groups of CME-streamer-Type-II events. In the first group, the shock as well as the Type-II radio emission seems to exist prior to the CME-streamer interaction. The interaction can be clearly discerned from the well-defined bump of the Type-II radio dynamic spectra. The spectral bump is a direct result of plasma emissions when the radio emitting region traversing the denser streamer structure. In the other group of events, the Type-II burst is excited as a result of the CME-streamer interaction. Either the shock is formed and radio-emitting electrons are accelerated inside the streamer, or a prior non-emitting shock becomes radio aloud during the interacting process. A novel triangular-streamer-shock model is proposed to interpret the associated electron acceleration inside the streamer. Observational examples of CME-streamer-radio events corresponding to both cases will be presented. [1] Chen, Y., Song, H.Q., Li, B., Xia, L.D., Wu, Z., Fu, H., Li, X., 2010, Astrophys. J. 714, 644 [2] Chen, Y., Feng, S.W., Li, B., Song, H.Q., Xia, L.D., Kong, X.L., Li, X., 2011, Astrophys. J. 728, 147 [3] Feng S. W., Chen Y., Li B., Song H. Q., Kong X. L., Xia L. D., Feng, X. S., 2011, Sol. Phys., DOI 10.1007/s11207-011-9814-6

  13. Expanded Outcomes Framework for Effective CME - The Way Forward for Pakistan.

    PubMed

    Vakani, Farhan; Amin, Almas

    2015-06-01

    Continuing Medical Education (CME) providers recognize the importance to plan educational activities that focus to improving and assessing knowledge, competency and performance outcomes rather than on attendance and satisfaction. This perspective proposes using an expanded outcomes framework for planning and assessing CME. The expanded outcomes framework supports backward planning, that starts with the population health outcomes (level 7) and moves backward, to providing continuing education for physicians that may result in improved outcomes. We the authors recognize the complexity of this framework, the recently evolved CME system in Pakistan, and the limited resources; and therefore, we suggest that planning and assessment should begin at level 3, physician knowledge. Thus, be mindful of the end and the scope of this framework that is associated and leads toward the improvement of population health outcomes. PMID:26101001

  14. Active galactic nucleus feedback in clusters of galaxies.

    PubMed

    Blanton, Elizabeth L; Clarke, T E; Sarazin, Craig L; Randall, Scott W; McNamara, Brian R

    2010-04-20

    Observations made during the last ten years with the Chandra X-ray Observatory have shed much light on the cooling gas in the centers of clusters of galaxies and the role of active galactic nucleus (AGN) heating. Cooling of the hot intracluster medium in cluster centers can feed the supermassive black holes found in the nuclei of the dominant cluster galaxies leading to AGN outbursts which can reheat the gas, suppressing cooling and large amounts of star formation. AGN heating can come in the form of shocks, buoyantly rising bubbles that have been inflated by radio lobes, and the dissipation of sound waves. PMID:20351250

  15. Active galactic nucleus feedback in clusters of galaxies

    PubMed Central

    Blanton, Elizabeth L.; Clarke, T. E.; Sarazin, Craig L.; Randall, Scott W.; McNamara, Brian R.

    2010-01-01

    Observations made during the last ten years with the Chandra X-ray Observatory have shed much light on the cooling gas in the centers of clusters of galaxies and the role of active galactic nucleus (AGN) heating. Cooling of the hot intracluster medium in cluster centers can feed the supermassive black holes found in the nuclei of the dominant cluster galaxies leading to AGN outbursts which can reheat the gas, suppressing cooling and large amounts of star formation. AGN heating can come in the form of shocks, buoyantly rising bubbles that have been inflated by radio lobes, and the dissipation of sound waves. PMID:20351250

  16. Interaction of metallic clusters with biologically active curcumin molecules

    NASA Astrophysics Data System (ADS)

    Gupta, Sanjeev K.; He, Haiying; Liu, Chunhui; Dutta, Ranu; Pandey, Ravindra

    2015-09-01

    We have investigated the interaction of subnano metallic Gd and Au clusters with curcumin, an important biomolecule having pharmacological activity. Gd clusters show different site preference to curcumin and much stronger interaction strength, in support of the successful synthesis of highly stable curcumin-coated Gd nanoparticles as reported recently. It can be attributed to significant charge transfer from the Gd cluster to curcumin together with a relatively strong hybridization of the Gd df-orbitals with curcumin p-orbitals. These results suggest that Gd nanoparticles can effectively be used as delivery carriers for curcumin at the cellular level for therapy and medical imaging applications.

  17. Active transport and cluster formation on 2D networks.

    PubMed

    Greulich, P; Santen, L

    2010-06-01

    We introduce a model for active transport on inhomogeneous networks embedded in a diffusive environment which is motivated by vesicular transport on actin filaments. In the presence of a hard-core interaction, particle clusters are observed that exhibit an algebraically decaying distribution in a large parameter regime, indicating the existence of clusters on all scales. The scale-free behavior can be understood by a mechanism promoting preferential attachment of particles to large clusters. The results are compared with a diffusion-limited aggregation model and active transport on a regular network. For both models we observe aggregation of particles to clusters which are characterized by a finite size scale if the relevant time scales and particle densities are considered. PMID:20556462

  18. Study of CME Properties Using High Resolution Data

    NASA Astrophysics Data System (ADS)

    Egorov, Ya. I.; Fainshtein, V. G.

    The joint use of high-resolution data from SDO and PROBA2 satellites and LASCO/SOHO coronographs enabled us to examine early stages of initiation and propagation of six limb CMEs registered in June 2010 - June 2011. For five events under consideration, the CME initiation is marked by filament (prominence) eruption or by a loop-like structure having another nature. Subsequently, several loop-like structures having higher brightness and following each other at different velocities appear in the region of the CME initiation. The CME frontal structure is formed by these loop-like structures. The CME kinematics and such CME characteristics as angular size and longitudinal to latitudinal size ratio was found for considered all events. We have drawn a conclusion about the possible existence of two CME types dependent on the velocity profile.

  19. Membrane-Active Peptides and the Clustering of Anionic Lipids

    PubMed Central

    Wadhwani, P.; Epand, R.F.; Heidenreich, N.; Bürck, J.; Ulrich, A.S.; Epand, R.M.

    2012-01-01

    There is some overlap in the biological activities of cell-penetrating peptides (CPPs) and antimicrobial peptides (AMPs). We compared nine AMPs, seven CPPs, and a fusion peptide with regard to their ability to cluster anionic lipids in a mixture mimicking the cytoplasmic membrane of Gram-negative bacteria, as measured by differential scanning calorimetry. We also studied their bacteriostatic effect on several bacterial strains, and examined their conformational changes upon membrane binding using circular dichroism. A remarkable correlation was found between the net positive charge of the peptides and their capacity to induce anionic lipid clustering, which was independent of their secondary structure. Among the peptides studied, six AMPs and four CPPs were found to have strong anionic lipid clustering activity. These peptides also had bacteriostatic activity against several strains (particularly Gram-negative Escherichia coli) that are sensitive to lipid clustering agents. AMPs and CPPs that did not cluster anionic lipids were not toxic to E. coli. As shown previously for several types of AMPs, anionic lipid clustering likely contributes to the mechanism of antibacterial action of highly cationic CPPs. The same mechanism could explain the escape of CPPs from intracellular endosomes that are enriched with anionic lipids. PMID:22853904

  20. Contributions from Ultraviolet Spectroscopy to the Prediction of High-energy Proton Hazards from CME Shocks

    NASA Astrophysics Data System (ADS)

    Lin, J.; Raymond, J. C.; Cranmer, S. R.; Kohl, J. L.

    2004-05-01

    A significant potential hazard to astronauts and their equipment in interplanetary space is the relativistic proton flux produced by coronal mass ejections (CMEs) and solar flares. The longest-duration phase of solar energetic particle (SEP) activity is believed to come from the CME shock as it propagates through the extended corona and heliosphere. Ultraviolet spectroscopy by SOHO has revealed a means for: (1) detecting and characterizing CME shocks in the corona, and (2) determining the plasma conditions in the pre-CME corona which are needed to understand the formation and evolution of shocks. Such remote sensing - combined with models of SEP acceleration and transport - can be used to predict the strength, duration, and production sites of the radiation. This poster describes the specific means by which ultraviolet spectroscopy and other remote-sensing data can be used to determine the inputs and boundary conditions for individual events (such as the October-November 2003 storms) in existing SEP model codes. We also discuss an additional potential source of SEP radiation associated with electric fields in the current sheets that form in flare regions in the wake of CME. Both observations and model calculations show that the reconnection-induced electric field can reach a maximum strength of a few V/cm within tens of minutes after the onset of the eruption, then decreases gradually over several hours. SEPs produced in these regions may account for X-rays and γ -rays observed prior to the formation of CME shocks. Ultraviolet spectroscopy has been shown to provide constraints on the plasma properties in all of the above CME features. This work is supported by NASA under grant NAG5-12865 to the Smithsonian Astrophysical Observatory, by Agenzia Spaziale Italiana, and by the Swiss contribution to ESA's PRODEX program.

  1. Numerical simulation of multiple CME-driven shocks in the month of 2011 September

    NASA Astrophysics Data System (ADS)

    Wu, Chin-Chun; Liou, Kan; Vourlidas, Angelos; Plunkett, Simon; Dryer, Murray; Wu, S. T.; Socker, Dennis; Wood, Brian E.; Hutting, Lynn; Howard, Russell A.

    2016-03-01

    A global, three-dimensional (3-D) numerical simulation model has been employed to study the Sun-to-Earth propagation of multiple (12) coronal mass ejections (CMEs) and their associated shocks in September 2011. The inputs to the simulation are based on actual solar observations, which include the CME speeds, source locations, and photospheric magnetic fields. The simulation result is fine tuned with in situ solar wind data observations at 1 AU by matching the arrival time of CME-driven shocks. During this period three CME-driven interplanetary (IP) shocks induced three sizable geomagnetic storms on 9, 17, and 26 September, with Dst values reaching -69, -70, and -101 nT, respectively. These storm events signify the commencement of geomagnetic activity in the solar cycle 24. The CME propagation speed near the Sun (e.g., < 30 RS) has been widely used to estimate the interplanetary CME (ICME)/Shock arrival time at 1 AU. Our simulation indicates that the background solar wind speed, as expected, is an important controlling parameter in the propagation of IP shocks and CMEs. Prediction of the ICME/shock arrival time at 1 AU can be more problematic for slow (e.g., < 500 km s-1) than fast CMEs (>1000 km s-1). This is because the effect of the background solar wind is more pronounced for slow CMEs. Here we demonstrate this difficulty with a slow (400 km s-1) CME event that arrived at the Earth in 3 days instead of the predicted 4.3 days. Our results also demonstrate that a long period (a month in this case) of simulation may be necessary to make meaningful solar source geomagnetic storm associations.

  2. Interrater Reliability to Assure Valid Content in Peer Review of CME-Accredited Presentations

    ERIC Educational Resources Information Center

    Quigg, Mark; Lado, Fred A.

    2009-01-01

    Introduction: The Accreditation Council for Continuing Medical Education (ACCME) provides guidelines for continuing medical education (CME) materials to mitigate problems in the independence or validity of content in certified activities; however, the process of peer review of materials appears largely unstudied and the reproducibility of…

  3. Deflected Propagation ---- A Factor Deciding the Geoeffectiveness of A CME

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Shen, C.; Liu, J.; Gui, B.; Wang, S.

    2010-12-01

    To answer the question if a CME can cause a significant change of the states of geo-space, the first issue we have to address is whether or not the CME will intersect with the Earth or what the trajectory of the CME is. From several observational cases and statistical studies, we show that the deflected propagations of CMEs are a common phenomenon. The amount of the deflection could be as large as several tens degrees in either latitude, longitude or both. Thus, an on-disk CME may not necessarily encounter the Earth, while a limb CME may be able to hit the Earth. Roughly, the CMEs' deflections can be classified as two different kinds. One is the deflection occurring in the corona, in which the CME's trajectory is controled by the distribution of the energy density of undisturbed coronal magnetic field. The other is that happenning in the IP space and in the ecliptic plane, in which the direction of the CME's propagation will be changed by the preceding or trailing background solar wind plasma depending on the velocity difference between the CME and ambient solar wind. Two models are proposed to describe the two different CME deflection behaviors, respectively. By applying the models to several cases, we may show that the trajectories of these CMEs predicted by the models match the observations fairly well.

  4. Radio active galactic nuclei in galaxy clusters: Feedback, merger signatures, and cluster tracers

    NASA Astrophysics Data System (ADS)

    Paterno-Mahler, Rachel Beth

    Galaxy clusters, the largest gravitationally-bound structures in the universe, are composed of 50-1000s of galaxies, hot X-ray emitting gas, and dark matter. They grow in size over time through cluster and group mergers. The merger history of a cluster can be imprinted on the hot gas, known as the intracluster medium (ICM). Merger signatures include shocks, cold fronts, and sloshing of the ICM, which can form spiral structures. Some clusters host double-lobed radio sources driven by active galactic nuclei (AGN). First, I will present a study of the galaxy cluster Abell 2029, which is very relaxed on large scales and has one of the largest continuous sloshing spirals yet observed in the X-ray, extending outward approximately 400 kpc. The sloshing gas interacts with the southern lobe of the radio galaxy, causing it to bend. Energy injection from the AGN is insufficient to offset cooling. The sloshing spiral may be an important additional mechanism in preventing large amounts of gas from cooling to very low temperatures. Next, I will present a study of Abell 98, a triple system currently undergoing a merger. I will discuss the merger history, and show that it is causing a shock. The central subcluster hosts a double-lobed AGN, which is evacuating a cavity in the ICM. Understanding the physical processes that affect the ICM is important for determining the mass of clusters, which in turn affects our calculations of cosmological parameters. To further constrain these parameters, as well as models of galaxy evolution, it is important to use a large sample of galaxy clusters over a range of masses and redshifts. Bent, double-lobed radio sources can potentially act as tracers of galaxy clusters over wide ranges of these parameters. I examine how efficient bent radio sources are at tracing high-redshift (z>0.7) clusters. Out of 646 sources in our high-redshift Clusters Occupied by Bent Radio AGN (COBRA) sample, 282 are candidate new, distant clusters of galaxies based on

  5. CME-CME Interaction As Revealed by MHD Simulations and SECCHI Observations

    NASA Astrophysics Data System (ADS)

    Lugaz, Noé; Farrugia, Charles; Roussev, Ilia; Moestl, Christian; Davies, Jackie; Gombosi, Tamas

    2012-07-01

    As we move towards solar maximum 24, immense progress can be expected in the forecasting and understanding of space weather and solar eruptions, thanks to the expanding fleet of satellites observing the Sun and the heliosphere (SOHO, Hinode, STEREO, SDO). As the frequency of coronal mass ejections (CMEs) increases to multiple eruptions per day, the interaction of successive CMEs in the inner heliosphere becomes more likely. CME-CME interaction is thought to be one major cause of intense and extreme geo-magnetic storms due to the compression of the magnetic field and the extended duration. In this talk, I will discuss how magneto-hydrodynamics (MHD) models and remote-sensing observations can shed light on the physical processes during CME-CME interaction and help explain complex in situ measurements at 1 AU. I will present some recent remote-sensing observations by STEREO/SECCHI of CMEs interacting in the heliosphere and discuss how knowledge gained from past numerical and observational studies may help us predict geo-effective events associated with multiple CMEs from remote-sensing observations.

  6. Sensitivity evaluation of dynamic speckle activity measurements using clustering methods

    SciTech Connect

    Etchepareborda, Pablo; Federico, Alejandro; Kaufmann, Guillermo H.

    2010-07-01

    We evaluate and compare the use of competitive neural networks, self-organizing maps, the expectation-maximization algorithm, K-means, and fuzzy C-means techniques as partitional clustering methods, when the sensitivity of the activity measurement of dynamic speckle images needs to be improved. The temporal history of the acquired intensity generated by each pixel is analyzed in a wavelet decomposition framework, and it is shown that the mean energy of its corresponding wavelet coefficients provides a suited feature space for clustering purposes. The sensitivity obtained by using the evaluated clustering techniques is also compared with the well-known methods of Konishi-Fujii, weighted generalized differences, and wavelet entropy. The performance of the partitional clustering approach is evaluated using simulated dynamic speckle patterns and also experimental data.

  7. Size-dependent catalytic activity of supported metal clusters

    NASA Astrophysics Data System (ADS)

    Xu, Z.; Xiao, F.-S.; Purnell, S. K.; Alexeev, O.; Kawi, S.; Deutsch, S. E.; Gates, B. C.

    1994-11-01

    BECAUSE catalysis by metals is a surface phenomenon, many technological catalysts contain small (typically nanometre-sized) supported metal particles with a large fraction of the atoms exposed1. Many reactions, such as hydrocarbon hydrogenations, are structure-insensitive, proceeding at approximately the same rate on metal particles of various sizes provided that they are larger than about 1 nm and show bulk-like metallic behaviour1. But it is not known whether the catalytic properties of metal particles become size-dependent as the particles become so small that they are no longer metallic in character. Here we investigate the catalytic behaviour of precisely defined clusters of just four and six iridium atoms on solid supports. We find that the Ir4 and Ir6 clusters differ in catalytic activity both from each other and from metallic Ir particles. This raises the possibility of tailoring the catalytic behaviour of metal clusters by controlling the cluster size.

  8. Identifying Clusters of Active Transportation Using Spatial Scan Statistics

    PubMed Central

    Huang, Lan; Stinchcomb, David G.; Pickle, Linda W.; Dill, Jennifer; Berrigan, David

    2009-01-01

    Background There is an intense interest in the possibility that neighborhood characteristics influence active transportation such as walking or biking. The purpose of this paper is to illustrate how a spatial cluster identification method can evaluate the geographic variation of active transportation and identify neighborhoods with unusually high/low levels of active transportation. Methods Self-reported walking/biking prevalence, demographic characteristics, street connectivity variables, and neighborhood socioeconomic data were collected from respondents to the 2001 California Health Interview Survey (CHIS; N=10,688) in Los Angeles County (LAC) and San Diego County (SDC). Spatial scan statistics were used to identify clusters of high or low prevalence (with and without age-adjustment) and the quantity of time spent walking and biking. The data, a subset from the 2001 CHIS, were analyzed in 2007–2008. Results Geographic clusters of significantly high or low prevalence of walking and biking were detected in LAC and SDC. Structural variables such as street connectivity and shorter block lengths are consistently associated with higher levels of active transportation, but associations between active transportation and socioeconomic variables at the individual and neighborhood levels are mixed. Only one cluster with less time spent walking and biking among walkers/bikers was detected in LAC, and this was of borderline significance. Age-adjustment affects the clustering pattern of walking/biking prevalence in LAC, but not in SDC. Conclusions The use of spatial scan statistics to identify significant clustering of health behaviors such as active transportation adds to the more traditional regression analysis that examines associations between behavior and environmental factors by identifying specific geographic areas with unusual levels of the behavior independent of predefined administrative units. PMID:19589451

  9. Ly-alpha and white light observations of a CME during the Spartan 201-1 mission

    NASA Technical Reports Server (NTRS)

    Hassler, Don M.; Strachan, Leonard; Gardner, L. D.; Kohl, J. L.; Guhathakurta, Madhulika; Fisher, Richard R.; Strong, K.

    1994-01-01

    A coronal mass ejection (CME) near a large active region on the west limb was observed with the white light coronograph (WLC) and ultraviolet coronal spectrometer (UVCS) on the Spartan 201 satellite at 9:42 UT on 12 Apr. 1993. Soft X-ray images of the region below the CME were obtained out to 1.7 solar radii with the soft X-ray telescope (SXT) on Yohkoh. After the event, the formation of a new helmet streamer could be seen in the polarized brightness (pB) images from the Mk III coronograph at Mauna Loa. The CME was observed from Spartan 201 in two different pB images obtained 14 min apart using the WLC, and was observed moving through the field-of-view of the UVCS integrated intensity slit. Ly-alpha intensities in the same region of the corona were obtained one orbit earlier (prior to the CME) using the Ly-alpha profile slit of the UVCS. These are the first Ly-alpha observations of a CME and may help constrain models of the electron temperature on CME's.

  10. Homologous Flare-CME Events and Their Metric Type II Radio Burst Association

    NASA Technical Reports Server (NTRS)

    Yashiro, S.; Gopalswamy, N.; Makela, P.; Akiyama, S.; Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Chandra, R.; Manoharan, P. K.; Mahalakshmi, K.; Dwivedi, V. C.; Jain, R.; Awasthi, A. K.; Nitta, N. V.; Aschwanden, M. J.; Choudhary, D. P.

    2014-01-01

    Active region NOAA 11158 produced many flares during its disk passage. At least two of these flares can be considered as homologous: the C6.6 flare at 06:51 UT and C9.4 flare at 12:41 UT on February 14, 2011. Both flares occurred at the same location (eastern edge of the active region) and have a similar decay of the GOES soft X-ray light curve. The associated coronal mass ejections (CMEs) were slow (334 and 337 km/s) and of similar apparent widths (43deg and 44deg), but they had different radio signatures. The second event was associated with a metric type II burst while the first one was not. The COR1 coronagraphs on board the STEREO spacecraft clearly show that the second CME propagated into the preceding CME that occurred 50 min before. These observations suggest that CME-CME interaction might be a key process in exciting the type II radio emission by slow CMEs.

  11. Obscured Starburst Activity in High-redshift Clusters and Groups

    NASA Astrophysics Data System (ADS)

    Kocevski, Dale D.; Lemaux, Brian C.; Lubin, Lori M.; Gal, Roy; McGrath, Elizabeth J.; Fassnacht, Christopher D.; Squires, Gordon K.; Surace, Jason A.; Lacy, Mark

    2011-07-01

    Using Spitzer-Multiband Imaging Photometer 24 μm imaging and extensive Keck spectroscopy, we examine the nature of the obscured star-forming population in three clusters and three groups at z ~ 0.9. These six systems are the primary components of the Cl1604 supercluster, the largest structure imaged by Spitzer at redshifts approaching unity. We find that the average density of 24 μm detected galaxies within the Cl1604 clusters is nearly twice that of the surrounding field and that this overdensity scales with the cluster's dynamical state. The 24 μm bright members often appear optically unremarkable and exhibit only moderate [O II] line emission due to severe obscuration. Their spatial distribution suggests that they are an infalling population, but an examination of their spectral properties, morphologies, and optical colors indicates that they are not simply analogs of the field population that have yet to be quenched. Using stacked composite spectra, we find that the 24 μm detected cluster and group galaxies exhibit elevated levels of Balmer absorption compared with galaxies undergoing normal, continuous star formation. A similar excess is not observed in field galaxies with equivalent infrared luminosities, indicating a greater fraction of the detected cluster and group members have experienced a burst of star formation in the recent past compared to their counterparts in the field. Our results suggest that gas-rich galaxies at high redshift experience a temporary increase in their star formation activity as they assemble into denser environments. Using Hubble Space Telescope Advanced Camera for Surveys imaging, we find that disturbed morphologies are common among the 24 μm detected cluster and group members and become more prevalent in regions of higher galaxy density. We conclude that mergers are the dominant triggering mechanism responsible for the enhanced star formation found in the Cl1604 groups, while a mix of harassment and mergers are likely

  12. Feasibility of a Knowledge Translation CME Program: "Courriels Cochrane"

    ERIC Educational Resources Information Center

    Pluye, Pierre; Grad, Roland; Granikov, Vera; Theriault, Guylene; Fremont, Pierre; Burnand, Bernard; Mercer, Jay; Marlow, Bernard; Arroll, Bruce; Luconi, Francesca; Legare, France; Labrecque, Michel; Ladouceur, Roger; Bouthillier, France; Sridhar, Soumya Bindiganavile; Moscovici, Jonathan

    2012-01-01

    Introduction: Systematic literature reviews provide best evidence, but are underused by clinicians. Thus, integrating Cochrane reviews into continuing medical education (CME) is challenging. We designed a pilot CME program where summaries of Cochrane reviews ("Courriels Cochrane") were disseminated by e-mail. Program participants automatically…

  13. Evaluating Conflicts of Interest in Research Presented in CME Venues

    ERIC Educational Resources Information Center

    Davis, Nancy L.; Galliher, James M.; Spano, Mindy S.; Main, Deborah S.; Brannigan, Michael; Pace, Wilson D.

    2008-01-01

    Introduction: There is much in the literature regarding the potential for commercial bias in clinical research and in continuing medical education (CME), but no studies were found regarding the potential for bias in reporting original research in CME venues. This pilot study investigated the presence of perceived bias in oral and print content of…

  14. Attendees' Perceptions of Commercial Influence in Noncommercially Funded CME Programs

    ERIC Educational Resources Information Center

    Goldfarb, Elizabeth; Baer, Lee; Fromson, John A.; Gorrindo, Tristan; Iodice, Kristin E.; Birnbaum, Robert J.

    2012-01-01

    Introduction: The controversy surrounding commercial support for continuing medical education (CME) programs has led to policy changes, but data show no significant difference in perceived bias between commercial and noncommercial CME. Indeed, what attendees perceive as commercial influence is not fully understood. We sought to clarify what…

  15. Developing an Instrument to Measure Bias in CME

    ERIC Educational Resources Information Center

    Takhar, Jatinder; Dixon, Dave; Donahue, Jill; Marlow, Bernard; Campbell, Craig; Silver, Ivan; Eadie, Jason; Monette, Celine; Rohan, Ivan; Sriharan, Abi; Raymond, Kathryn; Macnab, Jennifer

    2007-01-01

    Introduction: The pharmaceutical industry, by funding over 60% of programs in the United States and Canada, plays a major role in continuing medical education (CME), but there are concerns about bias in such CME programs. Bias is difficult to define, and currently no tool is available to measure it. Methods: Representatives from industry and…

  16. Tight Chk1 Levels Control Replication Cluster Activation in Xenopus

    PubMed Central

    Wiggins, Jennifer M.; Barbosa, Pedro; Libeau, Pierre; Priam, Pierre; Narassimprakash, Hemalatha; Grodzenski, Xenia; Marheineke, Kathrin

    2015-01-01

    DNA replication in higher eukaryotes initiates at thousands of origins according to a spatio-temporal program. The ATR/Chk1 dependent replication checkpoint inhibits the activation of later firing origins. In the Xenopus in vitro system initiations are not sequence dependent and 2-5 origins are grouped in clusters that fire at different times despite a very short S phase. We have shown that the temporal program is stochastic at the level of single origins and replication clusters. It is unclear how the replication checkpoint inhibits late origins but permits origin activation in early clusters. Here, we analyze the role of Chk1 in the replication program in sperm nuclei replicating in Xenopus egg extracts by a combination of experimental and modelling approaches. After Chk1 inhibition or immunodepletion, we observed an increase of the replication extent and fork density in the presence or absence of external stress. However, overexpression of Chk1 in the absence of external replication stress inhibited DNA replication by decreasing fork densities due to lower Cdk2 kinase activity. Thus, Chk1 levels need to be tightly controlled in order to properly regulate the replication program even during normal S phase. DNA combing experiments showed that Chk1 inhibits origins outside, but not inside, already active clusters. Numerical simulations of initiation frequencies in the absence and presence of Chk1 activity are consistent with a global inhibition of origins by Chk1 at the level of clusters but need to be combined with a local repression of Chk1 action close to activated origins to fit our data. PMID:26046346

  17. Flexible macrocycles as versatile supports for catalytically active metal clusters.

    PubMed

    Ryan, Jason D; Gagnon, Kevin J; Teat, Simon J; McIntosh, Ruaraidh D

    2016-07-12

    Here we present three structurally diverse clusters stabilised by the same macrocyclic polyphenol; t-butylcalix[8]arene. This work demonstrates the range of conformations the flexible ligand is capable of adopting, highlighting its versatility in metal coordination. In addition, a Ti complex displays activity for the ring-opening polymerisation of lactide. PMID:26892948

  18. EDI Data Products in the Cluster Active Archive

    NASA Astrophysics Data System (ADS)

    Georgescu, E.; Puhl-Quinn, P.; Vaith, H.; Chutter, M.; Quinn, J.; Paschmann, G.; Torbert, R.

    The Electron Drift Instrument (EDI) contribution to the Cluster Active Archive (CAA) is described. Presented are descriptions of the EDI instrument, the various CAA/EDI data products, the CAA ingestion schedule and the current EDI status. An example of a science application is given for one of the main EDI data products available in the CAA.

  19. Comprehensive STEREO Observations of the 2008 February 4 CME

    NASA Astrophysics Data System (ADS)

    Wood, B. E.; Howard, R. A.; Plunkett, S. P.; Socker, D. G.

    2008-12-01

    Thanks to the two Heliospheric Imagers that are part of STEREO's SECCHI instrument package, the two STEREO spacecraft are the first that are capable of following a CME continuously from the Sun all the way to 1 AU, where the PLASTIC and IMPACT instruments on the spacecraft can then also provide in situ information on the CME, assuming it hits one of the the two satellites. We present the first kinematic study of a CME that has been observed in such a comprehensive manner. The event begins on 2008 February 4 and is successfully tracked by STEREO-A to 1 AU where it hits STEREO-B on February 7. This is therefore a good example of STEREO's capability for one satellite (STEREO-A in this case) to observe a white-light CME front hitting the other satellite (STEREO-B in this case) at the same time as that second satellite is measuring the CME properties in situ.

  20. Obscured Starburst Activity in High Redshift Clusters and Groups

    NASA Astrophysics Data System (ADS)

    Kocevski, Dale; Lemaux, B.; Lubin, L.; Gal, R.

    2011-01-01

    Using Spitzer MIPS 24um imaging and extensive Keck spectroscopy we have found evidence for environmentally triggered starburst activity within six clusters and groups at z 0.9. I will show that the density of 24um-detected galaxies in the cluster environment is nearly twice that of the surrounding field at this redshift and that this overdensity scales with the cluster's dynamical state. The 24um-bright members often appear optically unremarkable and exhibit only moderate [OII] line emission due to severe obscuration. Although their spatial distribution suggests they are an infalling population, a close examination of their spectral properties, morphologies and optical colors indicate they are not simply analogs of the field population that have yet to be quenched. Using stacked DEIMOS spectra, we find the 24um-detected cluster and group galaxies exhibit elevated levels of Balmer absorption compared to galaxies undergoing normal, continuous star formation. A similar excess is not observed in field galaxies with equivalent infrared luminosities, indicating a greater fraction of the detected cluster and group members have experienced a burst of star formation in the recent past compared to their counterparts in the field. Our results suggest that gas-rich galaxies at high redshift experience a temporary increase in their star formation activity as they assemble into denser environments. Using HST ACS imaging we find that disturbed morphologies are common among the obscured starburst population and become more prevalent in regions of higher galaxy density. We conclude that mergers are the dominant triggering mechanism responsible for the enhanced star formation found in the group galaxies, while a mix of harassment and mergers are likely driving the activity of the cluster galaxies.

  1. Modeling Extreme Space Weather Scenarios: July 23, 2012 Rare-Type CME

    NASA Astrophysics Data System (ADS)

    Ngwira, C. M.; Pulkkinen, A. A.

    2014-12-01

    Space weather is a major concern for modern day society because of its adverse impacts on technological infrastructure such as power grids, oil pipelines, and global navigation systems. Particularly, earth directed coronal mass ejections (CMEs) are the main drivers of the most extreme geomagnetic storms in the near-Earth space environment. On 23 July 2012, NASA's Solar Terrestrial Relations Observatory-Ahead (STEREO-A) spacecraft observed in situ an extremely fast CME that traveled 0.96 astronomical units (~1 AU) in about 19 h. In our study, we use the Space Weather Modeling Framework (SWMF), a 3-D MHD based code, to perform simulations of this rare CME by considering STEREO-A in situ observations to represent the upstream L1 solar wind boundary conditions. The goal of the study is to investigate what would have happened if this Rare-type CME was Earth-bound. Global SWMF-generated ground geomagnetic field perturbations are used to compute the simulated induced geoelectric field at specific ground-based active magnetometer sites. Simulation results show that the July 23 CME would have produced ground effects comparable to previously observed extreme geomagnetic storms such as the Halloween 2003 storm. In addition, we discuss how this study compares to other independent studies on this same event.

  2. Do locations of CME source regions relative to the HSB determine the appearance of the CME?

    NASA Astrophysics Data System (ADS)

    Li, Y.; Luhmann, J. G.; Zhao, X. P.

    2002-05-01

    The relationship between CMEs and the coronal helmet streamer belt has been the subject of several studies. Recent studies using SOHO/LASCO observation presented a rather complicated picture of this relationship (Subramanian et al., 1999). It has been suggested that a CME may blowout, create, disturb, have no effect on or be clearly displaced from a streamer. We investigate the possibility that these different interactions may be due to the locations of the CME source regions relative to the helmet streamer belt. Estimated Helmet streamer belt configurations obtained using Potential Field Source Surface Models based on SOHO/MDI synoptic maps are compared with combined LASCO-EIT movies on the LASCO website for this study.

  3. Cluster Active Archive products and multipoint magnetospheric investigations

    NASA Astrophysics Data System (ADS)

    Perry, C.; Laakso, H.; Taylor, M.; Escoubet, P.

    2007-12-01

    The four-satellite Cluster mission investigates the small-scale structures (in three dimensions) of the Earth's plasma environment, such as those involved in the interaction between the solar wind and the magnetospheric plasma, in global magnetotail dynamics, in cross-tail currents, and in the formation and dynamics of the neutral line and of plasmoids. The Cluster Active Archive CAA (http://caa.estec.esa.int/) contains the entire set of Cluster high resolution data and other allied products in a standard format. The CAA currently has data from most of the Cluster instruments for at least the first three years of operations (2001-2003). The coverage and range of products is being continually improved with more than 200 datasets available from each spacecraft including high-resolution magnetic & electric DC fields and wave spectra; full 3D electron & ion distributions from a few eV to hundreds of keV; and various ancillary & browse products to help with spacecraft and event location. The data archived are (1) publicly accessible, (2) of the best quality achievable with the given resources, and (3) suitable for science use and publication by both the Cluster and broader scientific community. The presentation contains examples of user friendly services of the CAA for searching and accessing these data and ancillary products and of online capabilities of the system.

  4. CME impact on Mercury's sputtered exospheric environment

    NASA Astrophysics Data System (ADS)

    Pfleger, M.; Lichtenegger, H. I. M.; Lammer, H.; Mura, A.; Wurz, P.; Martin-Fernandez, J. A.

    2013-09-01

    Solar wind and magnetospheric plasma precipitation onto the surface of Mercury triggers the formation of exospheric particle populations by sputtering processes. Numerical modeling of Mercury's magnetosphere has shown that the weak intrinsic magnetic field of the planet is sufficient to prevent the equatorial regions from being impacted by solar wind ions during moderate solar wind conditions. However, intense fluxes of protons are expected to hit the auroral regions, giving rise to the release of surface elements at high latitudes by ion sputtering. During high solar wind dynamic pressure conditions in the case of CME events, the solar wind protons will have access to Mercury's entire dayside surface, which may result in a considerable filling of the exosphere by sputtered surface material.

  5. Clustering and phase behaviour of attractive active particles with hydrodynamics.

    PubMed

    Navarro, Ricard Matas; Fielding, Suzanne M

    2015-10-14

    We simulate clustering, phase separation and hexatic ordering in a monolayered suspension of active squirming disks subject to an attractive Lennard-Jones-like pairwise interaction potential, taking hydrodynamic interactions between the particles fully into account. By comparing the hydrodynamic case with counterpart simulations for passive and active Brownian particles, we elucidate the relative roles of self-propulsion, interparticle attraction, and hydrodynamic interactions in determining clustering and phase behaviour. Even in the presence of an attractive potential, we find that hydrodynamic interactions strongly suppress the motility induced phase separation that might a priori have been expected in a highly active suspension. Instead, we find only a weak tendency for the particles to form stringlike clusters in this regime. At lower activities we demonstrate phase behaviour that is broadly equivalent to that of the counterpart passive system at low temperatures, characterized by regimes of gas-liquid, gas-solid and liquid-solid phase coexistence. In this way, we suggest that a dimensionless quantity representing the level of activity relative to the strength of attraction plays the role of something like an effective non-equilibrium temperature, counterpart to the (dimensionless) true thermodynamic temperature in the passive system. However there are also some important differences from the equilibrium case, most notably with regards the degree of hexatic ordering, which we discuss carefully. PMID:26278520

  6. What Do EUV Dimmings Tell Us About CME Topology?

    NASA Astrophysics Data System (ADS)

    Thompson, B. J.; DeRosa, M. L.; Fisher, R. R.; Krista, L. D.; Kwon, R. Y.; Mason, J. P.; Mays, M. L.; Nitta, N.; Savani, N.; West, M. J.

    2014-12-01

    Large-scale coronal EUV dimmings, developing on timescales of minutes to hours in association with a flare or filament eruption, are known to exhibit a high correlation with coronal mass ejections. However, it is not clear why some CMEs have dimmings and some do not, nor is it clear how these dimmings relate to CME topology. The inner coronal coverage of SDO AIA and STEREO EUVI, combined with the extended field of view of PROBA2's SWAP imager, allow us the opportunity to map the topology of a dimming region in three dimensions into an erupting CME. Although the location and extent of a dimming region appears to be the best indicator of the inner "footprint" of a CME, the correlation is far from perfect. However, dimmings can provide vital clues about the development and 3D kinematics of a CME. This is particularly important as we are entering an extended period of time where STEREO coronagraph images will not always be available, and therefore the 3D properties of a CME will be difficult to deduce. Therefore, understanding the inner coronal manifestations of a CME can provide clues to its structure and dynamics, even without multi-viewpoint coronagraph observations. We present the results of this combined analysis effort, along with a discussion of how dimmings can be used in forecasting CME directions.

  7. CME Interaction with Large-Scale Coronal Structures

    NASA Technical Reports Server (NTRS)

    Gopalswarny, Nat

    2012-01-01

    This talk presents some key observations that highlight the importance of CME interaction with other large scale structures such as CMEs and coronal holes . Such interactions depend on the phase of the solar cycle: during maximum, CMEs are ejected more frequently, so CME-CME interaction becomes dominant. During the rise phase, the polar coronal holes are strong, so the interaction between polar coronal holes and CMEs is important, which also leads to a possible increase in the number of interplanetary CMEs observed as magnetic clouds. During the declining phase, there are more equatorial coronal holes, so CMEs originating near these coronal holes are easily deflected. CMEs can be deflected toward and away from the Sun-Earth line resulting in interesting geospace consequences. For example, the largest geomagnetic storm of solar cycle 23 was due to a CME that was deflected towards the Sun-earth line from E22. CME deflection away from the Sun-Earth line diminishes the chance of a CME producing a geomagnetic storm. CME interaction in the coronagraphic field of view was first identified using enhanced radio emission, which is an indication of acceleration of low energy (approx.10 keV) electrons in the interaction site. CME interaction, therefore, may also have implications for proton acceleration. For example, solar energetic particle events typically occur with a higher intensity, whenever multiple CMEs occur in quick succession from the same source region. CME deflection may also have implications to the arrival of energetic particles to earth because magnetic connectivity may be changed by the interaction. I illustrate the above points using examples from SOHO, STEREO, Wind, and ACE data .

  8. Composition and topology of activity cliff clusters formed by bioactive compounds.

    PubMed

    Stumpfe, Dagmar; Dimova, Dilyana; Bajorath, Jürgen

    2014-02-24

    The assessment of activity cliffs has thus far mostly focused on compound pairs, although the majority of activity cliffs are not formed in isolation but in a coordinated manner involving multiple active compounds and cliffs. However, the composition of coordinated activity cliff configurations and their topologies are unknown. Therefore, we have identified all activity cliff configurations formed by currently available bioactive compounds and analyzed them in network representations where activity cliff configurations occur as clusters. The composition, topology, frequency of occurrence, and target distribution of activity cliff clusters have been determined. A limited number of large cliff clusters with unique topologies were identified that were centers of activity cliff formation. These clusters originated from a small number of target sets. However, most clusters were of small to moderate size. Three basic topologies were sufficient to describe recurrent activity cliff cluster motifs/topologies. For example, frequently occurring clusters with star topology determined the scale-free character of the global activity cliff network and represented a characteristic activity cliff configuration. Large clusters with complex topology were often found to contain different combinations of basic topologies. Our study provides a first view of activity cliff configurations formed by currently available bioactive compounds and of the recurrent topologies of activity cliff clusters. Activity cliff clusters of defined topology can be selected, and from compounds forming the clusters, SAR information can be obtained. The SAR information of activity cliff clusters sharing a/one specific activity and topology can be compared. PMID:24437577

  9. Clues to galaxy activity from rich cluster simulations

    NASA Technical Reports Server (NTRS)

    Evrard, August E.

    1990-01-01

    New simulations of rich cluster evolution are used to evaluate the first infall hypothesis of Gunn and Dressler - the idea that the enhanced fraction of active galaxies seen in high redshift clusters is due to a one-time burst of star formation triggered by the rapid rise in external pressure as a galaxy plows into the hot intracluster medium (ICM). Using three-dimensional simulations which contain both baryonic gas and collisionless dark material, local static pressure histories for test orbits of galaxies are generated and a simple trigger threshold based on dP/dt/P sub ISM is applied to define an active fraction of the population. The results lend qualitative and quantitative support to the first infall interpretation.

  10. Active spacecraft potential control: An ion emitter experiment. [Cluster mission

    NASA Technical Reports Server (NTRS)

    Riedler, W.; Goldstein, R.; Hamelin, M.; Maehlum, B. N.; Troim, J.; Olsen, R. C.; Pedersen, A.; Grard, R. J. L.; Schmidt, R.; Rudenauer, F.

    1988-01-01

    The cluster spacecraft are instrumented with ion emitters for charge neutralization. The emitters produce indium ions at 6 keV. The ion current is adjusted in a feedback loop with instruments measuring the spacecraft potential. The system is based on the evaporation of indium in the apex field of a needle. The design of the active spacecraft potential control instruments, and the ion emitters is presented.

  11. Roles of Cluster Active Archive in heliophysics science research

    NASA Astrophysics Data System (ADS)

    McCaffrey, S.; Laakso, H.; Perry, C.; Taylor, M.; Escoubet, P.; Esson, S.; Herment, D.

    2007-12-01

    The four-satellite Cluster mission investigates small-scale structures (in three dimensions) of the Earth's plasma environment, such as those involved in the interaction between the solar wind and the magnetospheric plasma, in global magnetotail dynamics, in cross-tail currents, and in the formation and dynamics of the neutral line and of plasmoids. The Cluster Active Archive CAA (http://caa.estec.esa.int/) will contain the entire set of Cluster high resolution data and other allied products in a standard format and with a complete set of metadata in machine readable form. The data archived are (1) publicly accessible, (2) of the best quality achievable with the given resources, and (3) suitable for science use and publication by both the Cluster and broader scientific community. The CAA tends to provide user friendly services for searching and accessing these data, e.g., users can save their frequent data requests as profiles speeding up their future similar requests. The CAA is continuing to extend and improve the online capabilities of the system, e.g., the CAA products can be downloaded either via a web interface or a machine accessible interface.

  12. CME front and severe space weather

    NASA Astrophysics Data System (ADS)

    Balan, N.; Skoug, R.; Tulasi Ram, S.; Rajesh, P. K.; Shiokawa, K.; Otsuka, Y.; Batista, I. S.; Ebihara, Y.; Nakamura, T.

    2014-12-01

    Thanks to the work of a number of scientists who made it known that severe space weather can cause extensive social and economic disruptions in the modern high-technology society. It is therefore important to understand what determines the severity of space weather and whether it can be predicted. We present results obtained from the analysis of coronal mass ejections (CMEs), solar energetic particle (SEP) events, interplanetary magnetic field (IMF), CME-magnetosphere coupling, and geomagnetic storms associated with the major space weather events since 1998 by combining data from the ACE and GOES satellites with geomagnetic parameters and the Carrington event of 1859, the Quebec event of 1989, and an event in 1958. The results seem to indicate that (1) it is the impulsive energy mainly due to the impulsive velocity and orientation of IMF Bz at the leading edge of the CMEs (or CME front) that determine the severity of space weather. (2) CMEs having high impulsive velocity (sudden nonfluctuating increase by over 275 km s-1 over the background) caused severe space weather (SvSW) in the heliosphere (failure of the solar wind ion mode of Solar Wind Electron Proton Alpha Monitor in ACE) probably by suddenly accelerating the high-energy particles in the SEPs ahead directly or through the shocks. (3) The impact of such CMEs which also show the IMF Bz southward from the leading edge caused SvSW at the Earth including extreme geomagnetic storms of mean DstMP < -250 nT during main phases, and the known electric power outages happened during some of these SvSW events. (4) The higher the impulsive velocity, the more severe the space weather, like faster weather fronts and tsunami fronts causing more severe damage through impulsive action. (5) The CMEs having IMF Bz northward at the leading edge do not seem to cause SvSW on Earth, although, later when the IMF Bz turns southward, they can lead to super geomagnetic storms of intensity (Dstmin) less than even -400 nT.

  13. Chandra Finds Surprising Black Hole Activity In Galaxy Cluster

    NASA Astrophysics Data System (ADS)

    2002-09-01

    Scientists at the Carnegie Observatories in Pasadena, California, have uncovered six times the expected number of active, supermassive black holes in a single viewing of a cluster of galaxies, a finding that has profound implications for theories as to how old galaxies fuel the growth of their central black holes. The finding suggests that voracious, central black holes might be as common in old, red galaxies as they are in younger, blue galaxies, a surprise to many astronomers. The team made this discovery with NASA'S Chandra X-ray Observatory. They also used Carnegie's 6.5-meter Walter Baade Telescope at the Las Campanas Observatory in Chile for follow-up optical observations. "This changes our view of galaxy clusters as the retirement homes for old and quiet black holes," said Dr. Paul Martini, lead author on a paper describing the results that appears in the September 10 issue of The Astrophysical Journal Letters. "The question now is, how do these black holes produce bright X-ray sources, similar to what we see from much younger galaxies?" Typical of the black hole phenomenon, the cores of these active galaxies are luminous in X-ray radiation. Yet, they are obscured, and thus essentially undetectable in the radio, infrared and optical wavebands. "X rays can penetrate obscuring gas and dust as easily as they penetrate the soft tissue of the human body to look for broken bones," said co-author Dr. Dan Kelson. "So, with Chandra, we can peer through the dust and we have found that even ancient galaxies with 10-billion-year-old stars can have central black holes still actively pulling in copious amounts of interstellar gas. This activity has simply been hidden from us all this time. This means these galaxies aren't over the hill after all and our theories need to be revised." Scientists say that supermassive black holes -- having the mass of millions to billions of suns squeezed into a region about the size of our Solar System -- are the engines in the cores of

  14. SOHO Captures CME From X5.4 Solar Flare

    NASA Video Gallery

    The Solar Heliospheric Observatory (SOHO) captured this movie of the sun's coronal mass ejection (CME) associated with an X5.4 solar flare on the evening of March 6, 2012. The extremely fast and en...

  15. CME Onset and Take-Off

    NASA Technical Reports Server (NTRS)

    Antiochos, S. K.; Karpen, J. T.; DeVore, C. R.

    2011-01-01

    For understanding and eventually predicting coronal mass ejections/eruptive flares, two critical questions must be answered: What is the mechanism for eruption onset, and what is the mechanism for the rapid acceleration? We address these questions in the context of the breakout model using 2.5D MHD simulations with adaptive mesh refinement (AMR). The AMR capability allowed us to achieve ultra-high numerical resolution and, thereby, determine the influence of the effective Lundquist number on the eruption. Our calculations show that, at least, for the breakout model, the onset of reconnection external to the highly sheared filament channel is the onset mechanism. Once this reconnection turns on, eruption is inevitable. However, as long as this is the only reconnection in the system, the eruption remains slow. We find that the eruption undergoes an abrupt "take-off" when the flare reconnection below the erupting plasmoid develops significant reconnection jets. We conclude that in fast CMEs, flare reconnection is the primary mechanism responsible for both flare heating and CME acceleration. We discuss the implications of these results for SDO observations and describe possible tests of the model.

  16. Comparisons of Remote And In-situ CME Features

    NASA Astrophysics Data System (ADS)

    Reinard, Alysha; Mulligan, T.; Lynch, B.

    2011-05-01

    We present a comparison of remote and in-situ CME ejecta using data from the Ulysses and SOHO missions. Quadrature occurs when two spacecraft form a 90 degree angle with the Sun. Quadrature studies allow the comparison of visible features of limb CMEs and and in-situ ICME properties. We investigate several events, including so-called "cannibal" CMEs, and compare the relationship between CME morphology and in-situ structures such as magnetic field, composition, and plasma properties.

  17. Coronal Current Sheet Evolution in the Aftermath of a CME

    NASA Technical Reports Server (NTRS)

    Bemporad, A.; Poletto, G.; Suess, S. T.; Ko, Y.-K.; Schwadron, N. A.; Elliott, H. A.; Raymond, J. C.

    2005-01-01

    We report on SOHO-UVCS observations of coronal restructuring following a Coronal Mass Ejection (CME) on November 26, 2002, at the time of a SOHO-Ulysses quadrature campaign. Starting about 3 hours after the CME, which was directed towards Ulysses, UVCS began taking spectra at 1.7 solar radii, covering emission from both cool and hot plasma. Observations continued, with occasional gaps, for more than 2 days. Emission in the 974.8 Angstrom line of [Fe XVIII], indicating temperatures above 6x10(6) K, was observed throughout the campaign in a spatially limited location. Comparison with EIT images shows the [Fe XVIII] emission to overlie a growing post-flare loop system formed in the aftermath of the CME. The emission most likely originates in a current sheet overlying the arcade. Analysis of the [Fe XVIII] emission allows us to infer the evolution of physical parameters in the current sheet over the entire span of our observations: in particular, we give the temperature vs. time in the current sheet and estimate the density. Ulysses was directly above the location of the CME and intercepted the ejecta. High ionization state Fe was detected by SWICS throughout the magnetic cloud associated with the CME, although the rapid temporal variation suggests bursty, rather than smooth, reconnection in the coronal current sheet. Both the remote and in situ observations are compared with predictions of theoretical CME models.

  18. Current Sheet Evolution in the Aftermath of a CME Event

    NASA Technical Reports Server (NTRS)

    Bemporad, A.; Poletto, G.; Suess, S. T.; Ko, Y.-K.; Schwadron, N. A.; Elliott, H. A.; Raymond, J. C.

    2005-01-01

    We report on SOHO-UVCS observations of the coronal restructuring following a Coronal Mass Ejection (CME) on November 26,2002, at the time of a SOHO-Ulysses quadrature campaign. Starting about 3 hours after a CME in the NW quadrant, UVCS began taking spectra at 1.7 solar radius, covering emission from both cool and hot plasma. Observations continued, with occasional gaps, for more than 2 days. Emission in the 974.8 Angstrom line of [Fe XVIII], indicating temperatures above 6 x 10(exp 6) K, was observed throughout the campaign in a spatially limited location. Comparison with EIT images shows the Fe XVIII emission to overlie a growing post-flare loop system formed in the aftermath of the CME. The emission most likely originates in a current sheet overlying the arcade. Analysis of the [Fe XVIII] emission allows us to infer the evolution of physical parameters in the current sheet over the entire span of our observations: in particular, we give the temperature vs. time in the current sheet and estimate the density. At the time of the quadrature, Ulysses was directly above the location of the CME and intercepted the ejecta. High ionization state Fe was detected by Ulysses-SWICS throughout the magnetic cloud associated with the CME. Both the remote and in situ observations are compared with predictions of theoretical CME models.

  19. What Do EUV Dimmings Tell Us About CME Topology

    NASA Astrophysics Data System (ADS)

    Thompson, Barbara J.; DeRosa, Marc L.; Fisher, Richard R.; Krista, Larisza D.; Kwon, Ryun Young; Mason, James P.; Mays, Mona L.; Nitta, Nariaki V.; Webb, David F.; West, Matthew J.

    2015-04-01

    Large-scale coronal EUV dimmings develop on timescales of hours in association with a flare or filament eruption, and are known to be well correlated with coronal mass ejections (CMEs). However, it is not clear why some CMEs have dimmings and some do not, nor is it clear how these dimmings relate to CME topology. The inner coronal coverage of SDO AIA and STEREO EUVI, combined with the extended field of view of PROBA2's SWAP imager, allow us the opportunity to map the topology of a dimming region in three dimensions into an erupting CME. Although the location and extent of a dimming region appears to be the best indicator of the inner "footprint" of a CME, the correlation is far from perfect. However, dimmings can provide vital clues about the development and 3D kinematics of CMEs. This is particularly important as we are currently in an extended period where the STEREO coronagraph images are not always available and are increasingly "mirroring" LASCO images, and therefore the 3D properties of a CME will be difficult to deduce. Thus, understanding the inner coronal manifestations of a CME can provide clues to its structure and dynamics, even without multi-viewpoint coronagraph observations. We present the results of this combined analysis effort, along with a discussion of how dimmings can be used to forecast CME trajectories.

  20. The Nature of CME-flare-Associated Coronal Dimming

    NASA Astrophysics Data System (ADS)

    Cheng, J. X.; Qiu, J.

    2016-07-01

    Coronal mass ejections (CMEs) are often accompanied by coronal dimming that is evident in extreme ultraviolet (EUV) and soft X-ray observations. The locations of dimming are sometimes considered to map footpoints of the erupting flux rope. As the emitting material expands in the corona, the decreased plasma density leads to reduced emission observed in spectral and irradiance measurements. Therefore, signatures of dimming may reflect the properties of CMEs in the early phase of their eruption. In this study, we analyze the event of flare, CME, and coronal dimming on 2011 December 26. We use the data from the Atmospheric Imaging Assembly on the Solar Dynamics Observatory for disk observations of the dimming, and analyze images taken by EUVI, COR1, and COR2 on board the Solar Terrestrial Relations Observatory to obtain the height and velocity of the associated CMEs observed at the limb. We also measure the magnetic reconnection rate from flare observations. Dimming occurs in a few locations next to the flare ribbons, and it is observed in multiple EUV passbands. Rapid dimming starts after the onset of fast reconnection and CME acceleration, and its evolution tracks the CME height and flare reconnection. The spatial distribution of dimming exhibits cores of deep dimming with a rapid growth, and their light curves are approximately linearly scaled with the CME height profile. From the dimming analysis we infer the process of the CME expansion, and estimate properties of the CME.

  1. Star Formation Activity in CLASH Brightest Cluster Galaxies

    NASA Astrophysics Data System (ADS)

    Fogarty, Kevin; Postman, Marc; Connor, Thomas; Donahue, Megan; Moustakas, John

    2015-11-01

    The CLASH X-ray selected sample of 20 galaxy clusters contains 10 brightest cluster galaxies (BCGs) that exhibit significant (>5σ) extinction-corrected star formation rates (SFRs). Star formation activity is inferred from photometric estimates of UV and Hα+[N ii] emission in knots and filaments detected in CLASH Hubble Space Telescope ACS and WFC3 observations. UV-derived SFRs in these BCGs span two orders of magnitude, including two with a SFR ≳ 100 M⊙ yr-1. These measurements are supplemented with [O ii], [O iii], and Hβ fluxes measured from spectra obtained with the SOAR telescope. We confirm that photoionization from ongoing star formation powers the line emission nebulae in these BCGs, although in many BCGs there is also evidence of a LINER-like contribution to the line emission. Coupling these data with Chandra X-ray measurements, we infer that the star formation occurs exclusively in low-entropy cluster cores and exhibits a correlation with gas properties related to cooling. We also perform an in-depth study of the starburst history of the BCG in the cluster RXJ1532.9+3021, and create 2D maps of stellar properties on scales down to ˜350 pc. These maps reveal evidence for an ongoing burst occurring in elongated filaments, generally on ˜0.5-1.0 Gyr timescales, although some filaments are consistent with much younger (≲100 Myr) burst timescales and may be correlated with recent activity from the active galactic nucleus. The relationship between BCG SFRs and the surrounding intracluster medium gas properties provide new support for the process of feedback-regulated cooling in galaxy clusters and is consistent with recent theoretical predictions. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel

  2. The SCEC Community Modeling Environment(SCEC/CME): A Collaboratory for Seismic Hazard Analysis

    NASA Astrophysics Data System (ADS)

    Maechling, P. J.; Jordan, T. H.; Minster, J. B.; Moore, R.; Kesselman, C.

    2005-12-01

    The SCEC Community Modeling Environment (SCEC/CME) Project is an NSF-supported Geosciences/IT partnership that is actively developing an advanced information infrastructure for system-level earthquake science in Southern California. This partnership includes SCEC, USC's Information Sciences Institute (ISI), the San Diego Supercomputer Center (SDSC), the Incorporated Institutions for Research in Seismology (IRIS), and the U.S. Geological Survey. The goal of the SCEC/CME is to develop seismological applications and information technology (IT) infrastructure to support the development of Seismic Hazard Analysis (SHA) programs and other geophysical simulations. The SHA application programs developed on the Project include a Probabilistic Seismic Hazard Analysis system called OpenSHA. OpenSHA computational elements that are currently available include a collection of attenuation relationships, and several Earthquake Rupture Forecasts (ERFs). Geophysicists in the collaboration have also developed Anelastic Wave Models (AWMs) using both finite-difference and finite-element approaches. Earthquake simulations using these codes have been run for a variety of earthquake sources. Rupture Dynamic Model (RDM) codes have also been developed that simulate friction-based fault slip. The SCEC/CME collaboration has also developed IT software and hardware infrastructure to support the development, execution, and analysis of these SHA programs. To support computationally expensive simulations, we have constructed a grid-based scientific workflow system. Using the SCEC grid, project collaborators can submit computations from the SCEC/CME servers to High Performance Computers at USC and TeraGrid High Performance Computing Centers. Data generated and archived by the SCEC/CME is stored in a digital library system, the Storage Resource Broker (SRB). This system provides a robust and secure system for maintaining the association between the data seta and their metadata. To provide an easy

  3. CME-related particle acceleration regions during a simple eruptive event near solar minimum

    NASA Astrophysics Data System (ADS)

    Salas Matamoros, Carolina; Klein, Karl-Ludwig; Rouillard, Alexis

    2016-04-01

    An intriguing feature of many solar energetic particle (SEP) events is the detection of particles over a very extended range of longitudes in the Heliosphere. This may be due to peculiarities of the magnetic field in the corona, to a broad accelerator, to cross-field transport of the particles, or to a combination of these processes. The eruptive flare of the 26th of April 2008 offered an opportunity to study relevant processes under particularly favorable conditions, since it occurred in a very quiet solar and interplanetary environment. This allowed us to investigate the physical link between a single well-identified Coronal Mass Ejection (CME), electron acceleration as traced by radio emission, and the production of SEPs. We conduct a detailed analysis combining radio observations (Nançay Radioheliograph and Decameter Array, Wind/WAVES spectrograph) with remote-sensing observations of the corona in extreme ultraviolet (EUV) and white light as well as in-situ measurements of energetic particles near 1AU (SoHO and STEREO spacecraft). By combining images taken from multiple vantage points we were able to derive the time-dependent evolution of the 3-D pressure front developing around the erupting CME. Magnetic reconnection in the post-CME current sheet accelerated electrons that remained confined in closed magnetic fields in the corona, while the acceleration of escaping particles can be attributed to the pressure front generated ahead of the expanding CME. The CME accelerated electrons remotely from the parent active region, due to the interaction of its laterally expanding flank, traced by an EUV wave, with the ambient corona. SEPs detected at one STEREO spacecraft and SoHO were accelerated later, when the frontal shock of the CME intercepted the spacecraft-connected interplanetary magnetic field line. The injection regions into the Heliosphere inferred from the radio and SEP observations are separated in longitude by about 140°. The observations for this event

  4. Asymmetry in the CME-CME interaction process for the events from 2011 February 14-15

    SciTech Connect

    Temmer, M.; Veronig, A. M.; Peinhart, V.; Vršnak, B.

    2014-04-20

    We present a detailed study of the interaction process of two coronal mass ejections (CMEs) successively launched on 2011 February 14 (CME1) and 2011 February 15 (CME2). Reconstructing the three-dimensional shape and evolution of the flux ropes, we verify that the two CMEs interact. The frontal structure of both CMEs, measured along different position angles (PAs) over the entire latitudinal extent, reveals differences in the kinematics for the interacting flanks and the apexes. The interaction process is strongly PA-dependent in terms of timing as well as kinematical evolution. The central interaction occurs along PA-100°, which shows the strongest changes in kinematics. During interaction, CME1 accelerates from ∼400 km s{sup –1} to ∼700 km s{sup –1} and CME2 decelerates from ∼1300 km s{sup –1} to ∼600 km s{sup –1}. Our results indicate that a simplified scenario such as inelastic collision may not be sufficient to describe the CME-CME interaction. The magnetic field structures of the intertwining flux ropes and the momentum transfer due to shocks each play an important role in the interaction process.

  5. Statistics of Active Galactic Nuclei in Rich Clusters Revisited

    NASA Astrophysics Data System (ADS)

    Way, M. J.; Flores, R. A.; Quintana, H.

    1998-07-01

    Using the spectrophotometry of a large sample of galaxies in 19 Abell clusters, we have selected 42 candidate active galactic nuclei (AGNs) using the criteria used by Dressler and coworkers in their analysis of the statistics of 22 AGNs in 14 rich cluster fields, which are based on the equivalent width of [O II] 3727 Å, Hβ, and [O III] 5007 Å emission. We have then discriminated AGNs from H II region-like galaxies (hereafter H II galaxies) in the manner developed by Veilleux & Osterbrock using the additional information provided by Hα and [N II] 6583 Å or Hα and [S II] 6716 + 6731 Å emission, in order to test the reliability of the selection criteria used by Dressler and coworkers. We find that before we discriminate AGNs from H II galaxies, our sample is very similar to that of Dressler and coworkers and it leads to similar conclusions. However, we find that their method inevitably mixes H II galaxies with AGNs, even for the most luminous objects in our sample. We estimate a contamination of at least 38% at a formal 90% confidence level. Since the study of Dressler and coworkers, other authors have attempted to quantify the relative fraction of cluster-to-field AGNs and have reached similar conclusions, but they have used criteria similar to Dressler and coworkers to select AGNs (or have used the [O III] 5007 Å/Hβ flux ratio test that also mixes H II galaxies with AGNs). Our sample of true AGNs remains too small to reach statistically meaningful conclusions, therefore a new study with a more time-consuming method that includes the other lines will be required to quantify the true relative fraction of cluster-to-field AGNs.

  6. Postsynaptic Clustering and Activation of Pyk2 by PSD-95

    PubMed Central

    Bartos, Jason A.; Ulrich, Jason D.; Li, Hongbin; Beazely, Michael A.; Chen, Yucui; MacDonald, John F.; Hell, Johannes W.

    2010-01-01

    The tyrosine kinase Pyk2 plays a unique role in intracellular signal transduction by linking Ca2+ influx to tyrosine phosphorylation, but the molecular mechanism of Pyk2 activation is unknown. We report that Pyk2 oligomerization by antibodies in vitro or overexpression of PSD-95 in PC6-3 cells induces trans-autophosphorylation of Tyr402, the first step in Pyk2 activation. In neurons, Ca2+ influx through NMDA-type glutamate receptors (NMDAR) causes postsynaptic clustering and autophosphorylation of endogenous Pyk2 via Ca2+- and calmodulin-stimulated binding to PSD-95. Accordingly, Ca2+ influx promotes oligomerization and thereby autoactivation of Pyk2 by stimulating its interaction with PSD-95. We show that this mechanism of Pyk2 activation is critical for LTP in the hippocampus CA1 region, which is thought to underlie learning and memory. PMID:20071509

  7. Solar Flare, CME, and Proton Event Rates Correlated with Sunspot Number

    NASA Astrophysics Data System (ADS)

    Winter, L. M.; Balasubramaniam, K. S.; Pernak, R.

    2015-12-01

    The newly revised sunspot number series allows for placing historical geoeffective storms in the context of several hundred years of solar activity. Using statistical analyses of the GOES X-ray and differential particle observations from the past ~30 years and the SOHO/LASCO CME catalog (1996-present), we present sunspot number dependent predictions for expected flare, SEP, and CME rates. In particular, we present X-ray flare rates as a function of sunspot number for the past three cycles. We also show, as in the attached figure, that the 1-8 Angstrom background flux is strongly correlated with sunspot number across solar cycles. Similarly, we show that the CME properties (e.g., velocity and width) are also correlated with sunspot number for cycles 23 and 24. Finally, SEP rates and background proton flux levels are also scaled to sunspot number. These rates will enable future predictions for geoeffective events and place historical storms in context of present solar activity.

  8. CME impact on comet 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Edberg, Niklas J. T.; Alho, M.; André, M.; Andrews, D. J.; Behar, E.; Burch, J. L.; Carr, C. M.; Cupido, E.; Engelhardt, I. A. D.; Eriksson, A. I.; Glassmeier, K.-H.; Goetz, C.; Goldstein, R.; Henri, P.; Johansson, F. L.; Koenders, C.; Mandt, K.; Nilsson, H.; Odelstad, E.; Richter, I.; Simon Wedlund, C.; Stenberg Wieser, G.; Szego, K.; Vigren, E.; Volwerk, M.

    2016-08-01

    We present Rosetta observations from comet 67P/Churyumov-Gerasimenko during the impact of a coronal mass ejection (CME). The CME impacted on 5-6 Oct 2015, when Rosetta was about 800 km from the comet nucleus, and 1.4 AU from the Sun. Upon impact, the plasma environment is compressed to the level that solar wind ions, not seen a few days earlier when at 1500 km, now reach Rosetta. In response to the compression, the flux of suprathermal electrons increases by a factor of 5-10 and the background magnetic field strength increases by a factor of ˜2.5. The plasma density increases by a factor of 10 and reaches 600 cm-3, due to increased particle impact ionisation, charge exchange and the adiabatic compression of the plasma environment. We also observe unprecedentedly large magnetic field spikes at 800 km, reaching above 200 nT, which are interpreted as magnetic flux ropes. We suggest that these could possibly be formed by magnetic reconnection processes in the coma as the magnetic field across the CME changes polarity, or as a consequence of strong shears causing Kelvin-Helmholtz instabilities in the plasma flow. Due to the limited orbit of Rosetta, we are not able to observe if a tail disconnection occurs during the CME impact, which could be expected based on previous remote observations of other CME-comet interactions.

  9. Numerical Simulation of a Slow Streamer-Blowout CME

    NASA Astrophysics Data System (ADS)

    Lynch, Benjamin J.; Masson, Sophie; Li, Yan; DeVore, C. Richard; Luhmann, Janet; Antiochos, Spiro K.

    2014-06-01

    We present a 3D numerical MHD simulation of the 2008 Jun 2 gradual streamer blowout CME that had virtually no identifiable low coronal signatures. We energize the field by simple footpoint shearing along the source region's polarity inversion line and model the background solar wind structure using an ˜2MK isothermal wind and a low-order potential field source surface representation of the CR2070 synoptic magnetogram. Our results show that the CME ``initiation’’ is obtained by slowly disrupting the quasi-steady-state configuration of the helmet streamer, resulting in the standard eruptive flare picture that ejects the sheared fields, but very slowly, on a relatively large scale, and with very little magnetic energy release. We obtain a relatively slow CME eruption of order the background solar wind speed and argue that these slow streamer blowout CMEs (now also known as ``stealth CMEs’’) are simply at the lowest end of the CME energy distribution. We present comparisons of the CME propagation through the corona (≤15Rs) in synthetic white-light images derived from the simulation density structure with multi-spacecraft coronagraph data from STEREO/SECCHI and SOHO/LASCO.

  10. Topological Evolution of a Fast Magnetic Breakout CME in 3-Dimensions

    NASA Technical Reports Server (NTRS)

    Lynch, B. J.; Antiochos, S. K.; DeVore, C. R.; Luhmann, J. G.; Zurbuchen, T. H.

    2008-01-01

    W present the extension of the magnetic breakout model for CME initiation to a fully 3-dimensional, spherical geometry. Given the increased complexity of the dynamic magnetic field interactions in 3-dimensions, we first present a summary of the well known axisymmetric breakout scenario in terms of the topological evolution associated with the various phases of the eruptive process. In this context, we discuss the completely analogous topological evolution during the magnetic breakout CME initiation process in the simplest 3-dimensional multipolar system. We show that an extended bipolar active region embedded in an oppositely directed background dipole field has all the necessary topological features required for magnetic breakout, i.e. a fan separatrix surface between the two distinct flux systems, a pair of spine fieldlines, and a true 3-dimensional coronal null point at their intersection. We then present the results of a numerical MHD simulation of this 3-dimensional system where boundary shearing flows introduce free magnetic energy, eventually leading to a fast magnetic breakout CME. The eruptive flare reconnection facilitates the rapid conversion of this stored free magnetic energy into kinetic energy and the associated acceleration causes the erupting field and plasma structure to reach an asymptotic eruption velocity of greater than or approx. equal to 1100 km/s over an approx.15 minute time period. The simulation results are discussed using the topological insight developed to interpret the various phases of the eruption and the complex, dynamic, and interacting magnetic field structures.

  11. Capillary microextraction (CME) and its application to trace elements analysis and their speciation.

    PubMed

    Hu, Bin; Zheng, Fei; He, Man; Zhang, Nan

    2009-09-14

    As a solvent-free miniaturized sample preparation technique, capillary microextraction (CME) has been hyphenated with different analytical instruments for trace elements analysis of environmental, biological, food and pharmaceutical samples. This review discusses the fundamentals and recent development of CME, including the theoretical basis, extraction modes (packed, open-tubular and monolithic CME) and capillary materials for CME. The emphasis is placed on the application of CME to trace/ultra-trace elements analysis and their speciation. Existing coating/monolithic materials used for CME are summarized together with a detailed overview of their preparation methods. PMID:19720168

  12. A Gamblers Clustering Based on Their Favorite Gambling Activity.

    PubMed

    Challet-Bouju, Gaëlle; Hardouin, Jean-Benoit; Renard, Noëlle; Legauffre, Cindy; Valleur, Marc; Magalon, David; Fatséas, Mélina; Chéreau-Boudet, Isabelle; Gorsane, Mohamed-Ali; Vénisse, Jean-Luc; Grall-Bronnec, Marie

    2015-12-01

    The objective of this study was to identify profiles of gamblers to explain the choice of preferred gambling activity among both problem and non-problem gamblers. 628 non-problem and problem gamblers were assessed with a structured interview including "healthy" (sociodemographic characteristics, gambling habits and personality profile assessed with the Temperament and Character Inventory-125) and "pathological" [diagnosis of pathological gambling, gambling-related cognitions (GRCs) and psychiatric comorbidity] variables. We performed a two-step cluster analysis based solely on "healthy" variables to identify gamblers' profiles which typically reflect the choice of preferred gambling activity. The obtained classes were then described using both "healthy" and "pathological" variables, by comparing each class to the rest of the sample. Clusters were generated. Class 1 (Electronic Gaming Machines gamblers) showed high cooperativeness, a lower level of GRC about strategy and more depressive disorders. Class 2 (games with deferred results gamblers) were high novelty seekers and showed a higher level of GRC about strategy and more addictive disorders. Class 3 (roulette gamblers) were more often high rollers and showed a higher level of GRC about strategy and more manic or hypomanic episodes and more obsessive-compulsive disorders. Class 4 (instant lottery gamblers) showed a lower tendency to suicide attempts. Class 5 (scratch cards gamblers) were high harm avoiders and showed a lower overall level of GRC and more panic attacks and eating disorders. The preference for one particular gambling activity may concern different profiles of gamblers. This study highlights the importance of considering the pair gambler-game rather than one or the other separately, and may provide support for future research on gambling and preventive actions directed toward a particular game. PMID:25192752

  13. Usability and quality of the Cluster Active Archive (Invited)

    NASA Astrophysics Data System (ADS)

    Laakso, H. E.

    2009-12-01

    There is a large number of data archives for magnetospheric physics that, however, usually provide access only to spin-averaged datasets. In addition only limited resources have been used to calibrate the measurements to a level that the users could easily analyze them with no need to worry about the quality of the data. These are the starting points to the ESA Cluster Active Archive (CAA, see URL: http://caa.estec.esa.int) that provides access to the calibrated full-resolution datasets of the four-satellite Cluster mission. The data archive is publicly accessible and suitable for science use and publication by the world-wide scientific community. This presentation will focus on the usability aspects of the overall system and its services and the quality of its datasets. The Cluster mission has collected observations for nine years since 2001 and has now submitted a proposal for further observations during years 2010-12. The CAA will contain the entire set of Cluster high-resolution data and other allied products in a standard format and with a complete set of metadata in machine readable format. The data can be accessed either via web GUI or via command line wget tool. Currently there are more than 200 datasets from each spacecraft, including high-resolution magnetic and electric DC and AC fields; full 3-dimensional electron and ion distribution functions and moments from a few eV to hundreds of keV; and various ancillary and browse products to help with spacecraft and event location. To ensure the high quality of its datasets, the CAA runs a series of cross-calibration workshops that focus on detailed comparisons of the measurements. Currently the observations from years 2001-7 are available for most instruments. The total amount of data files in compressed format is expected to exceed 50 TB. The CAA became operational in February 2006 and now has more than 900 registered users who download about 100-1000 GB of data every month. The CAA provides user

  14. Global modeling of CME propagation in the solar wind

    NASA Astrophysics Data System (ADS)

    Pizzo, V. J.

    Begging the question of build-up, initiation, and launch, our ability to model the propagation of CMEs out into the interplanetary medium depends upon (1) how well we can characterize the timing, location, geometry, and dynamical content of the ejecta in the lower corona; (2) how well we know the background flow into which the CME propagates; and (3) how well we can describe the subsequent interaction between CME and the structured, background, quasi-steady wind. Simulations of CMEs are needed to help interpret observations of complicated transient structures and are essential to space weather applications. We assess where we stand in terms of observational and simulation capabilities for CME propagation models and offer suggestions for further development.

  15. Current Sheet Evolution In The Aftermath Of A CME Event

    NASA Technical Reports Server (NTRS)

    Bemporad, A.; Poletto, G.; Seuss, S. T.; Schwardron, N. A.; Elliott, H. A.; Raymond, J. C.

    2006-01-01

    We report on SOHO UVCS observations of the coronal restructuring following a coronal mass ejection (CME) on 2002 November 26, at the time of a SOHO-Ulysses quadrature campaign. Starting about 1.5 hr after a CME in the northwest quadrant, UVCS began taking spectra at 1.7 R, covering emission from both cool and hot plasma. Observations continued, with occasional gaps, for more than 2 days. Emission in the 974.8 A line of [Fe XVIII], indicating temperatures above 6 x 10(exp 6) K, was observed throughout the campaign in a spatially limited location. Comparison with EIT images shows the [Fe XVIII] emission to overlie a growing post-flare loop system formed in the aftermath of the CME. The emission most likely originates in a current sheet overlying the arcade. Analysis of the [Fe XVIII] emission allows us to infer the evolution of physical parameters in the current sheet over the entire span of our observations: in particular, we give the temperature versus time in the current sheet and estimate its density. At the time of the quadrature, Ulysses was directly above the location of the CME and intercepted the ejecta. High ionization state Fe was detected by the Ulysses SWICS throughout the magnetic cloud associated with the CME, although its rapid temporal variation suggests bursty, rather than smooth, reconnection in the coronal current sheet. The SOHO-Ulysses data set provided us with the unique opportunity of analyzing a current sheet structure from its lowest coronal levels out to its in situ properties. Both the remote and in situ observations are compared with predictions of theoretical CME models.

  16. How Environment Affects Star Formation: Tracing Activity in High Redshift Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Alberts, Stacey; Pope, A.; Brodwin, M.; Atlee, D. W.; Lin, Y.; Chary, R.; Dey, A.; Eisenhardt, P. R.; Gettings, D.; Gonzalez, A. H.; Jannuzi, B.; Mancone, C.; Moustakas, J.; Snyder, G. F.; Stanford, S. A.; Stern, D.; Weiner, B. J.; Zeimann, G.

    2014-01-01

    The emerging picture of the evolution of cluster galaxies indicates that the epoch of z>1 is a crucial period of active star formation and mass assembly in clusters. In this dissertation, I leverage a uniformly-selected cluster sample from the IRAC Shallow Cluster Survey (ISCS) with Herschel imaging to analyse the star formation (SF) activity in cluster galaxies over the past ten billion years. This analysis is two-fold: 1) using 274 clusters across the 9 square degree Bootes field, I perform a stacking analysis of mass-limited samples of cluster and field galaxies using wide-field Herschel observations over a long redshift baseline, z=0.3-1.5. I find that the average SF activity in cluster galaxies is evolving faster than in the field, with field-like SF in the cluster cores and enhanced SF activity in the cluster outskirts at z>1.2. By further breaking down my analysis by galaxy mass and type, I determine which mechanisms are capable of driving this evolution. 2) I use unique, deep Herschel imaging of 11 spectroscopically-confirmed clusters from z=1.1-1.8 to study the properties of individual infrared bright cluster galaxies as a function of redshift and cluster-centric radius. Combined with ancillary data, I determine the star formation, dust, and AGN properties of the most active cluster galaxies and tie the evolution of these properties back to the environment by comparing to field populations. By combining these two approaches, I constrain cluster galaxy properties during a pivotal epoch of dust-obscured star formation activity and mass assembly in some of the most extreme structures in the Universe.

  17. Validation of CME Detection Software (CACTus) by Means of Simulated Data, and Analysis of Projection Effects on CME Velocity Measurements

    NASA Astrophysics Data System (ADS)

    Bonte, K.; Jacobs, C.; Robbrecht, E.; de Groof, A.; Berghmans, D.; Poedts, S.

    2011-05-01

    In the context of space weather forecasting, an automated detection of coronal mass ejections (CMEs) becomes more and more important for efficiently handling a large data flow which is expected from recently-launched and future solar missions. In this paper we validate the detection software package "CACTus" by applying the program to synthetic data from our 3D time-dependent CME simulations instead of observational data. The main strength of this study is that we know in advance what should be detected. We describe the sensitivities and strengths of automated detection, more specific for the CACTus program, resulting in a better understanding of CME detection on one hand and the calibration of the CACTus software on the other hand, suggesting possible improvements of the package. In addition, the simulation is an ideal tool to investigate projection effects on CME velocity measurements.

  18. The Successive CME on 13th; 14th and 15th February 2011 and Forbush decrease on 18 February 2011

    NASA Astrophysics Data System (ADS)

    Maričić, D.; Bostasyan, N.; Dumbović, M.; Chilingarian, A.; Mailyan, B.; Rostomyan, H.; Arakelyan, K.; Vršnak, B.; Roša, D.; Hržina, D.; Romštajn, I.; Veronig, A.

    2013-02-01

    Aims. We analyze the kinematics of three interplanetary coronal mass ejections (ICMEs) that occurred on 13th, 14th and 15th February 2011 in the active region AR 11155 and have shown that they appeared at the Earth orbit on February, 18th and caused Forbush decrease (FD). Methods. The solar coordinates of flares are (S19W03), (S20W14) and (S21W18). The kinematic curves were obtained using STEREO (A&B) data. Additionally, we explore the possibility of the CME-CME interaction for these three events. We compare obtained estimates of ICME arrival with the in-situ measurements from WIND satellite at L1 point and with ground-based cosmic ray data obtained from SEVAN network. Results. The acceleration of each CME is highly correlated with the associated SXR flares energy release. CMEs that erupted at 13 and 14 Feb 2011 are not associated with prominence eruption; maximum velocity was vmax550 ± 50 km/s and vmax400 ± 50 km/s, respectively. However, 15 Feb 2011 CME is connected with much more violent eruption associated with a prominence, with maximum velocity of vmax 1400 ± 50 km/s. The last overtakes 13th and 14th Feb CMEs at distances of 32 and 160 Rsolar, respectively.

  19. Simulation of the 23 July 2012 extreme space weather event: What if this extremely rare CME was Earth directed?

    NASA Astrophysics Data System (ADS)

    Ngwira, Chigomezyo M.; Pulkkinen, Antti; Leila Mays, M.; Kuznetsova, Maria M.; Galvin, A. B.; Simunac, Kristin; Baker, Daniel N.; Li, Xinlin; Zheng, Yihua; Glocer, Alex

    2013-12-01

    Extreme space weather events are known to cause adverse impacts on critical modern day technological infrastructure such as high-voltage electric power transmission grids. On 23 July 2012, NASA's Solar Terrestrial Relations Observatory-Ahead (STEREO-A) spacecraft observed in situ an extremely fast coronal mass ejection (CME) that traveled 0.96 astronomical units (˜1 AU) in about 19 h. Here we use the Space Weather Modeling Framework (SWMF) to perform a simulation of this rare CME. We consider STEREO-A in situ observations to represent the upstream L1 solar wind boundary conditions. The goal of this study is to examine what would have happened if this Rare-type CME was Earth-bound. Global SWMF-generated ground geomagnetic field perturbations are used to compute the simulated induced geoelectric field at specific ground-based active INTERMAGNET magnetometer sites. Simulation results show that while modeled global SYM-H index, a high-resolution equivalent of the Dst index, was comparable to previously observed severe geomagnetic storms such as the Halloween 2003 storm, the 23 July CME would have produced some of the largest geomagnetically induced electric fields, making it very geoeffective. These results have important practical applications for risk management of electrical power grids.

  20. Simulation of the 23 July 2012 Extreme Space Weather Event: What if This Extremely Rare CME Was Earth Directed?

    NASA Technical Reports Server (NTRS)

    Ngwira, Chigomezyo M.; Pulkkinen, Antti; Mays, M. Leila; Kuznetsova, Maria M.; Galvin, A. B.; Simunac, Kristin; Baker, Daniel N.; Li, Xinlin; Zheng, Yihua; Glocer, Alex

    2013-01-01

    Extreme space weather events are known to cause adverse impacts on critical modern day technological infrastructure such as high-voltage electric power transmission grids. On 23 July 2012, NASA's Solar Terrestrial Relations Observatory-Ahead (STEREO-A) spacecraft observed in situ an extremely fast coronal mass ejection (CME) that traveled 0.96 astronomical units (approx. 1 AU) in about 19 h. Here we use the SpaceWeather Modeling Framework (SWMF) to perform a simulation of this rare CME.We consider STEREO-A in situ observations to represent the upstream L1 solar wind boundary conditions. The goal of this study is to examine what would have happened if this Rare-type CME was Earth-bound. Global SWMF-generated ground geomagnetic field perturbations are used to compute the simulated induced geoelectric field at specific ground-based active INTERMAGNET magnetometer sites. Simulation results show that while modeled global SYM-H index, a high-resolution equivalent of the Dst index, was comparable to previously observed severe geomagnetic storms such as the Halloween 2003 storm, the 23 July CME would have produced some of the largest geomagnetically induced electric fields, making it very geoeffective. These results have important practical applications for risk management of electrical power grids.

  1. Improving CME: Using Participant Satisfaction Measures to Specify Educational Methods

    ERIC Educational Resources Information Center

    Olivieri, Jason J.; Regala, Roderick P.

    2013-01-01

    Imagine having developed a continuing medical education (CME) initiative to educate physicians on updated guidelines regarding high cholesterol in adults. This initiative consisted of didactic presentations and case-based discussions offered in 5 major US cities, followed by a Web-based enduring component to distill key points of the live…

  2. Quality framework proposal for Component Material Evaluation (CME) projects.

    SciTech Connect

    Christensen, Naomi G.; Arfman, John F.; Limary, Siviengxay

    2008-09-01

    This report proposes the first stage of a Quality Framework approach that can be used to evaluate and document Component Material Evaluation (CME) projects. The first stage of the Quality Framework defines two tools that will be used to evaluate a CME project. The first tool is used to decompose a CME project into its essential elements. These elements can then be evaluated for inherent quality by looking at the subelements that impact their level of quality maturity or rigor. Quality Readiness Levels (QRLs) are used to valuate project elements for inherent quality. The Framework provides guidance for the Principal Investigator (PI) and stakeholders for CME project prerequisites that help to ensure the proper level of confidence in the deliverable given its intended use. The Framework also Provides a roadmap that defined when and how the Framework tools should be applied. Use of these tools allow the Principal Investigator (PI) and stakeholders to understand what elements the project will use to execute the project, the inherent quality of the elements, which of those are critical to the project and why, and the risks associated to the project's elements.

  3. The new CORIMP CME catalog & 3D reconstructions

    NASA Astrophysics Data System (ADS)

    Byrne, Jason; Morgan, Huw; Gallagher, Peter; Habbal, Shadia; Davies, Jackie

    2015-04-01

    A new coronal mass ejection catalog has been built from a unique set of coronal image processing techniques, called CORIMP, that overcomes many of the limitations of current catalogs in operation. An online database has been produced for the SOHO/LASCO data and event detections therein; providing information on CME onset time, position angle, angular width, speed, acceleration, and mass, along with kinematic plots and observation movies. The high-fidelity and robustness of these methods and derived CME structure and kinematics will lead to an improved understanding of the dynamics of CMEs, and a realtime version of the algorithm has been implemented to provide CME detection alerts to the interested space weather community. Furthermore, STEREO data has been providing the ability to perform 3D reconstructions of CMEs that are observed in multipoint observations. This allows a determination of the 3D kinematics and morphologies of CMEs characterised in STEREO data via the 'elliptical tie-pointing' technique. The associated observations of SOHO, SDO and PROBA2 (and intended use of K-Cor) provide additional measurements and constraints on the CME analyses in order to improve their accuracy.

  4. Acceleration and Deceleration of Coronal Mass Ejection (CME) Propagation

    NASA Astrophysics Data System (ADS)

    Shen, F.; Wu, S.; Feng, X. S.; Wu, C.

    2011-12-01

    A major challenge to the space weather forecasting community is accurate prediction of coronal mass ejections (CME) induced Shock Arrival Time (SAT) at Earth's environment. In order to improve the current accuracy, it is necessary to understand the physical processes of the acceleration and deceleration of the CME propagation in the heliosphere. We present a three-dimensional (3D) magnetohydrodynamic (MHD) simulation of the evolution of two interacting CMEs in a realistic ambient solar wind for the March 28-31, 2001 event. The forces which caused the acceleration and deceleration are analyzed in detail. The force which caused the acceleration are Lorenz force and pressure gradient and the forces which caused the deceleration are aerodynamic drag and the Sun's gravity. In addition the momentum exchange between the solar wind and the moving CMEs can cause acceleration and deceleration of the CME which are now analyzed. In this specific CME event (March 28-31, 2001), we also investigate the interactions of two CMEs causing the acceleration and deceleration of the CMEs.

  5. Determining CME-driven shock parameters from remote sensing observations

    NASA Astrophysics Data System (ADS)

    Volpes, L.; Bothmer, V.

    2016-02-01

    Coronal mass ejections (CMEs) are large scale eruptions of magnetized plasma propagating from the Sun into interplanetary space with speeds varying from a few tens to more than 2500 km s-1. They cause large-scale turbulence in the heliosphere and are the major drivers of space weather. Fast CMEs drive strong shocks in the corona and interplanetary medium and generate plasma turbulence in the post-shock regions ahead of the CME bodies. In this work results from the detailed analysis of a strong CME and shock event on April 3, 2010 are summarized. For this event the solar source region is identified and the CME and shock kinematics are determined from time series of white light images obtained by the SECCHI suite on board the STEREO spacecrafts. The shock's standoff distance, compression ratio and Mach number are derived. A comparison of the derived values with the in-situ measurements shows good agreement. Further comparison of the shock MHD parameters determined from remote sensing observations with in-situ data, including the calculation of power-spectra, will help validating the results and provide new insights into CME generated turbulence. The study will be extended to further events identified in STEREO observations.

  6. Clustering and Pattern Formation in Chemorepulsive Active Colloids

    NASA Astrophysics Data System (ADS)

    Liebchen, Benno; Marenduzzo, Davide; Pagonabarraga, Ignacio; Cates, Michael E.

    2015-12-01

    We demonstrate that migration away from self-produced chemicals (chemorepulsion) generates a generic route to clustering and pattern formation among self-propelled colloids. The clustering instability can be caused either by anisotropic chemical production, or by a delayed orientational response to changes of the chemical environment. In each case, chemorepulsion creates clusters of a self-limiting area which grows linearly with self-propulsion speed. This agrees with recent observations of dynamic clusters in Janus colloids (albeit not yet known to be chemorepulsive). More generally, our results could inform design principles for the self-assembly of chemorepulsive synthetic swimmers and/or bacteria into nonequilibrium patterns.

  7. Clustering and Pattern Formation in Chemorepulsive Active Colloids.

    PubMed

    Liebchen, Benno; Marenduzzo, Davide; Pagonabarraga, Ignacio; Cates, Michael E

    2015-12-18

    We demonstrate that migration away from self-produced chemicals (chemorepulsion) generates a generic route to clustering and pattern formation among self-propelled colloids. The clustering instability can be caused either by anisotropic chemical production, or by a delayed orientational response to changes of the chemical environment. In each case, chemorepulsion creates clusters of a self-limiting area which grows linearly with self-propulsion speed. This agrees with recent observations of dynamic clusters in Janus colloids (albeit not yet known to be chemorepulsive). More generally, our results could inform design principles for the self-assembly of chemorepulsive synthetic swimmers and/or bacteria into nonequilibrium patterns. PMID:26722949

  8. Didactic CME and Practice Change: Don't Throw that Baby out Quite yet

    ERIC Educational Resources Information Center

    Olson, Curtis A.; Tooman, Tricia R.

    2012-01-01

    Skepticism exists regarding the role of continuing medical education (CME) in improving physician performance. The harshest criticism has been reserved for didactic CME. Reviews of the scientific literature on the effectiveness of CME conclude that formal or didactic modes of education have little or no impact on clinical practice. This has led…

  9. Obstetrician/Gynecologists and Postpartum Mental Health: Differences between CME Course Takers and Nontakers

    ERIC Educational Resources Information Center

    Leddy, Meaghan A.; Farrow, Victoria A.; Joseph, Gerald F., Jr.; Schulkin, Jay

    2012-01-01

    Introduction: Continuing medical education (CME) courses are an essential component of professional development. Research indicates a continued need for understanding how and why physicians select certain CME courses, as well as the differences between CME course takers and nontakers. Purpose: Obstetrician-gynecologists (OB-GYNs) are health care…

  10. Adults' Physical Activity Patterns across Life Domains: Cluster Analysis with Replication

    PubMed Central

    Rovniak, Liza S.; Sallis, James F.; Saelens, Brian E.; Frank, Lawrence D.; Marshall, Simon J.; Norman, Gregory J.; Conway, Terry L.; Cain, Kelli L.; Hovell, Melbourne F.

    2010-01-01

    Objective Identifying adults' physical activity patterns across multiple life domains could inform the design of interventions and policies. Design Cluster analysis was conducted with adults in two US regions (Baltimore-Washington DC, n = 702; Seattle-King County, n = 987) to identify different physical activity patterns based on adults' reported physical activity across four life domains: leisure, occupation, transport, and home. Objectively measured physical activity, and psychosocial and built (physical) environment characteristics of activity patterns were examined. Main Outcome Measures Accelerometer-measured activity, reported domain-specific activity, psychosocial characteristics, built environment, body mass index (BMI). Results Three clusters replicated (kappa = .90-.93) across both regions: Low Activity, Active Leisure, and Active Job. The Low Activity and Active Leisure adults were demographically similar, but Active Leisure adults had the highest psychosocial and built environment support for activity, highest accelerometer-measured activity, and lowest BMI. Compared to the other clusters, the Active Job cluster had lower socioeconomic status and intermediate accelerometer-measured activity. Conclusion Adults can be clustered into groups based on their patterns of accumulating physical activity across life domains. Differences in psychosocial and built environment support between the identified clusters suggest that tailored interventions for different subgroups may be beneficial. PMID:20836604

  11. Ion acceleration near CME-driven interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Desai, Mihir; Dayeh, Maher; Smith, Charles; Mason, Glenn; Lee, Martin

    2012-05-01

    We have surveyed properties of the magnetic field power spectral densities and energetic ions and compared them with the shock normal angles of 74 CME-driven IP shocks observed at ACE and Wind during solar cycle 23. We searched for events that exhibited clear signatures of first-order Fermi acceleration at quasi-parallel shocks and shock-drift acceleration at quasi-perpendicular shocks as predicted by the diffusive shock acceleration theory. Our results show that events with clear signatures of either shock-drift or first-order Fermi acceleration at 1 AU are rare, with 64 of the 74 IP shocks (~87%) exhibiting mixed signatures. We classify the remaining ten events as follows. (1) Four quasi-perpendicular shocks with θBn>70° exhibit no enhancements in the magnetic field power spectrum around the proton gyro-frequency and a slight hardening or no change in the ~80-300 keV/nucleon CNO spectral index across the shocks, indicating the absence of upstream wave activity and the re-acceleration of a pre-existing suprathermal seed spectrum. (2) Six quasi-parallel or oblique IP shocks with θBn<70° exhibit significant enhancements in the power spectral densities around the proton gyro-frequency and are accompanied by unfolding (softening) of the ~80-300 keV/nucleon CNO spectral index across the shocks, indicating the acceleration and efficient trapping of <300 keV/nucleon CNO ions by the Alfvén waves that were most likely excited by the accelerated protons as they streamed away from the shocks. In this paper, we present contrasting energetic particle and magnetic field observations near 2 IP shocks at 1 AU to highlight the complex signatures associated with the two distinct types of shock acceleration mechanisms.

  12. Effect of mitochondrial complex I inhibition on Fe-S cluster protein activity

    SciTech Connect

    Mena, Natalia P.; Bulteau, Anne Laure; Salazar, Julio; Hirsch, Etienne C.; Nunez, Marco T.

    2011-06-03

    Highlights: {yields} Mitochondrial complex I inhibition resulted in decreased activity of Fe-S containing enzymes mitochondrial aconitase and cytoplasmic aconitase and xanthine oxidase. {yields} Complex I inhibition resulted in the loss of Fe-S clusters in cytoplasmic aconitase and of glutamine phosphoribosyl pyrophosphate amidotransferase. {yields} Consistent with loss of cytoplasmic aconitase activity, an increase in iron regulatory protein 1 activity was found. {yields} Complex I inhibition resulted in an increase in the labile cytoplasmic iron pool. -- Abstract: Iron-sulfur (Fe-S) clusters are small inorganic cofactors formed by tetrahedral coordination of iron atoms with sulfur groups. Present in numerous proteins, these clusters are involved in key biological processes such as electron transfer, metabolic and regulatory processes, DNA synthesis and repair and protein structure stabilization. Fe-S clusters are synthesized mainly in the mitochondrion, where they are directly incorporated into mitochondrial Fe-S cluster-containing proteins or exported for cytoplasmic and nuclear cluster-protein assembly. In this study, we tested the hypothesis that inhibition of mitochondrial complex I by rotenone decreases Fe-S cluster synthesis and cluster content and activity of Fe-S cluster-containing enzymes. Inhibition of complex I resulted in decreased activity of three Fe-S cluster-containing enzymes: mitochondrial and cytosolic aconitases and xanthine oxidase. In addition, the Fe-S cluster content of glutamine phosphoribosyl pyrophosphate amidotransferase and mitochondrial aconitase was dramatically decreased. The reduction in cytosolic aconitase activity was associated with an increase in iron regulatory protein (IRP) mRNA binding activity and with an increase in the cytoplasmic labile iron pool. Since IRP activity post-transcriptionally regulates the expression of iron import proteins, Fe-S cluster inhibition may result in a false iron deficiency signal. Given that

  13. A Tiny Eruptive Filament as a Flux-Rope Progenitor and Driver of a Large-Scale CME and Wave

    NASA Astrophysics Data System (ADS)

    Grechnev, V. V.; Uralov, A. M.; Kochanov, A. A.; Kuzmenko, I. V.; Prosovetsky, D. V.; Egorov, Y. I.; Fainshtein, V. G.; Kashapova, L. K.

    2016-04-01

    A solar eruptive event SOL2010-06-13 observed with the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO) has been extensively discussed in the contexts of the CME development and an associated extreme-ultraviolet (EUV) wave-like transient in terms of a shock driven by the apparent CME rim. Continuing the analysis of this event, we have revealed an erupting flux rope, studied its properties, and detected wave signatures inside the developing CME. These findings have allowed us to establish new features in the genesis of the CME and associated EUV wave and to reconcile all of the episodes into a single causally related sequence. i) A hot 11 MK flux rope developed from the structures initially associated with a compact filament system. The flux rope expanded with an acceleration of up to 3 km s-2 one minute before a hard X-ray burst and earlier than any other structures, reached a velocity of 420 km s-1, and then decelerated to about 50 km s-1. ii) The CME development was driven by the expanding flux rope. Closed coronal structures above the rope got sequentially involved in the expansion from below upwards, came closer together, and apparently disappeared to reveal their common envelope, the visible rim, which became the outer boundary of the cavity. The rim was probably associated with the separatrix surface of a magnetic domain, which contained the pre-eruptive filament. iii) The rim formation was associated with a successive compression of the upper active-region structures into the CME frontal structure (FS). When the rim was formed, it resembled a piston. iv) The disturbance responsible for the consecutive CME formation episodes was excited by the flux rope inside the rim, and then propagated outward. EUV structures arranged at different heights started to accelerate, when their trajectories in the distance-time diagram were crossed by that of the fast front of this disturbance. v) Outside the rim and FS, the disturbance propagated like

  14. A Full Study on the Sun-Earth Connection of an Earth-directed CME Magnetic Flux Rope

    NASA Astrophysics Data System (ADS)

    Vemareddy, Panditi; Mishra, Wageesh

    2015-11-01

    We present an investigation of an eruption event of a coronal mass ejection (CME) magnetic flux rope (MFR) from the source active region (AR) NOAA 11719 on 2013 April 11 utilizing observations from the Solar Dynamic Observatory, the Solar Terrestrial Relations Observatory, the Solar and Heliospheric Observatory, and the WIND spacecraft. The source AR consists of a pre-existing sigmoidal structure stacked over a filament channel which is regarded as an MFR system. EUV observations of low corona suggest further development of this MFR system by added axial flux through tether-cutting reconnection of loops at the middle of the sigmoid under the influence of continuous slow flux motions for two days. Our study implies that the MFR system in the AR is initiated to upward motion by kink instability and further driven by torus instability. The CME morphology, captured in simultaneous three-point coronagraph observations, is fitted with a Graduated Cylindrical Shell (GCS) model and discerns an MFR topology with its orientation aligning with a magnetic neutral line in the source AR. This MFR expands self-similarly and is found to have source AR twist signatures in the associated near-Earth magnetic cloud (MC). We further derived the kinematics of this CME propagation by employing a plethora of stereoscopic as well as single-spacecraft reconstruction techniques. While stereoscopic methods perform relatively poorly compared to other methods, fitting methods worked best in estimating the arrival time of the CME compared to in situ measurements. Supplied with the values of constrained solar wind velocity, drag parameter, and three-dimensional kinematics from the GCS fit, we construct CME kinematics from the drag-based model consistent with in situ MC arrival.

  15. A Full Study on the Sun–Earth Connection of an Earth-directed CME Magnetic Flux Rope

    NASA Astrophysics Data System (ADS)

    Vemareddy, Panditi; Mishra, Wageesh

    2015-11-01

    We present an investigation of an eruption event of a coronal mass ejection (CME) magnetic flux rope (MFR) from the source active region (AR) NOAA 11719 on 2013 April 11 utilizing observations from the Solar Dynamic Observatory, the Solar Terrestrial Relations Observatory, the Solar and Heliospheric Observatory, and the WIND spacecraft. The source AR consists of a pre-existing sigmoidal structure stacked over a filament channel which is regarded as an MFR system. EUV observations of low corona suggest further development of this MFR system by added axial flux through tether-cutting reconnection of loops at the middle of the sigmoid under the influence of continuous slow flux motions for two days. Our study implies that the MFR system in the AR is initiated to upward motion by kink instability and further driven by torus instability. The CME morphology, captured in simultaneous three-point coronagraph observations, is fitted with a Graduated Cylindrical Shell (GCS) model and discerns an MFR topology with its orientation aligning with a magnetic neutral line in the source AR. This MFR expands self-similarly and is found to have source AR twist signatures in the associated near-Earth magnetic cloud (MC). We further derived the kinematics of this CME propagation by employing a plethora of stereoscopic as well as single-spacecraft reconstruction techniques. While stereoscopic methods perform relatively poorly compared to other methods, fitting methods worked best in estimating the arrival time of the CME compared to in situ measurements. Supplied with the values of constrained solar wind velocity, drag parameter, and three-dimensional kinematics from the GCS fit, we construct CME kinematics from the drag-based model consistent with in situ MC arrival.

  16. Night-time neuronal activation of Cluster N in a day- and night-migrating songbird

    PubMed Central

    Zapka, Manuela; Heyers, Dominik; Liedvogel, Miriam; Jarvis, Erich D; Mouritsen, Henrik

    2010-01-01

    Magnetic compass orientation in a night-migratory songbird requires that Cluster N, a cluster of forebrain regions, is functional. Cluster N, which receives input from the eyes via the thalamofugal pathway, shows high neuronal activity in night-migrants performing magnetic compass-guided behaviour at night, whereas no activation is observed during the day, and covering up the birds’ eyes strongly reduces neuronal activation. These findings suggest that Cluster N processes light-dependent magnetic compass information in night-migrating songbirds. The aim of this study was to test if Cluster N is active during daytime migration. We used behavioural molecular mapping based on ZENK activation to investigate if Cluster N is active in the meadow pipit (Anthus pratensis), a day- and night-migratory species. We found that Cluster N of meadow pipits shows high neuronal activity under dim-light at night, but not under full room-light conditions during the day. These data suggest that, in day- and night-migratory meadow pipits, the light-dependent magnetic compass, which requires an active Cluster N, may only be used during night-time, whereas another magnetosensory mechanism and/or other reference system(s), like the sun or polarized light, may be used as primary orientation cues during the day. PMID:20618826

  17. Removing Cool Cores and Central Metallicity Peaks in Galaxy Clusters with Powerful Active Galactic Nucleus Outbursts

    NASA Astrophysics Data System (ADS)

    Guo, Fulai; Mathews, William G.

    2010-07-01

    Recent X-ray observations of galaxy clusters suggest that cluster populations are bimodally distributed according to central gas entropy and are separated into two distinct classes: cool core (CC) and non-cool core (NCC) clusters. While it is widely accepted that active galactic nucleus (AGN) feedback plays a key role in offsetting radiative losses and maintaining many clusters in the CC state, the origin of NCC clusters is much less clear. At the same time, a handful of extremely powerful AGN outbursts have recently been detected in clusters, with a total energy ~1061-1062 erg. Using two-dimensional hydrodynamic simulations, we show that if a large fraction of this energy is deposited near the centers of CC clusters, which is likely common due to dense cores, these AGN outbursts can completely remove CCs, transforming them to NCC clusters. Our model also has interesting implications for cluster abundance profiles, which usually show a central peak in CC systems. Our calculations indicate that during the CC to NCC transformation, AGN outbursts efficiently mix metals in cluster central regions and may even remove central abundance peaks if they are not broad enough. For CC clusters with broad central abundance peaks, AGN outbursts decrease peak abundances, but cannot effectively destroy the peaks. Our model may simultaneously explain the contradictory (possibly bimodal) results of abundance profiles in NCC clusters, some of which are nearly flat, while others have strong central peaks similar to those in CC clusters. A statistical analysis of the sizes of central abundance peaks and their redshift evolution may shed interesting insights on the origin of both types of NCC clusters and the evolution history of thermodynamics and AGN activity in clusters.

  18. Circadian secretion of cortisol and melatonin in cluster headache during active cluster periods and remission.

    PubMed Central

    Waldenlind, E; Gustafsson, S A; Ekbom, K; Wetterberg, L

    1987-01-01

    The cyclic nature of cluster headache warranted a study of the 24-hour rhythms of serum cortisol and melatonin. They were both altered during cluster periods as compared with periods of remission and healthy controls. The 24-hour mean and maximal cortisol levels were higher and the timing of the cortisol minimum was delayed as compared to the same patients in remission. Although there was no relation between the cortisol and melatonin levels and headaches, the rise of cortisol following many attacks might in part represent an adaptive response to pain. The nocturnal melatonin maximum was lower during cluster periods than in remission. This finding, and the dysautonomic signs during attacks, may reflect a change of the vegetative tone in a hyposympathetic direction. Images PMID:3572435

  19. Coronal magnetic reconnection driven by CME expansion—the 2011 June 7 event

    SciTech Connect

    Van Driel-Gesztelyi, L.; Baker, D.; Green, L. M.; Williams, D. R.; Carlyle, J.; Kliem, B.; Long, D. M.; Matthews, S. A.; Török, T.; Pariat, E.; Valori, G.; Démoulin, P.; Malherbe, J.-M.

    2014-06-10

    Coronal mass ejections (CMEs) erupt and expand in a magnetically structured solar corona. Various indirect observational pieces of evidence have shown that the magnetic field of CMEs reconnects with surrounding magnetic fields, forming, e.g., dimming regions distant from the CME source regions. Analyzing Solar Dynamics Observatory (SDO) observations of the eruption from AR 11226 on 2011 June 7, we present the first direct evidence of coronal magnetic reconnection between the fields of two adjacent active regions during a CME. The observations are presented jointly with a data-constrained numerical simulation, demonstrating the formation/intensification of current sheets along a hyperbolic flux tube at the interface between the CME and the neighboring AR 11227. Reconnection resulted in the formation of new magnetic connections between the erupting magnetic structure from AR 11226 and the neighboring active region AR 11227 about 200 Mm from the eruption site. The onset of reconnection first becomes apparent in the SDO/AIA images when filament plasma, originally contained within the erupting flux rope, is redirected toward remote areas in AR 11227, tracing the change of large-scale magnetic connectivity. The location of the coronal reconnection region becomes bright and directly observable at SDO/AIA wavelengths, owing to the presence of down-flowing cool, dense (10{sup 10} cm{sup –3}) filament plasma in its vicinity. The high-density plasma around the reconnection region is heated to coronal temperatures, presumably by slow-mode shocks and Coulomb collisions. These results provide the first direct observational evidence that CMEs reconnect with surrounding magnetic structures, leading to a large-scale reconfiguration of the coronal magnetic field.

  20. Reactivity and Catalytic Activity of Hydrogen Atom Chemisorbed Silver Clusters.

    PubMed

    Manzoor, Dar; Pal, Sourav

    2015-06-18

    Metal clusters of silver have attracted recent interest of researchers as a result of their potential in different catalytic applications and low cost. However, due to the completely filled d orbital and very high first ionization potential of the silver atom, the silver-based catalysts interact very weakly with the reacting molecules. In the current work, density functional theory calculations were carried out to investigate the effect of hydrogen atom chemisorption on the reactivity and catalytic properties of inert silver clusters. Our results affirm that the hydrogen atom chemisorption leads to enhancement in the binding energy of the adsorbed O2 molecule on the inert silver clusters. The increase in the binding energy is also characterized by the decrease in the Ag-O and increase in the O-O bond lengths in the case of the AgnH silver clusters. Pertinent to the increase in the O-O bond length, a significant red shift in the O-O stretching frequency is also noted in the case of the AgnH silver clusters. Moreover, the hydrogen atom chemisorbed silver clusters show low reaction barriers and high heat of formation of the final products for the environmentally important CO oxidation reaction as compared to the parent catalytically inactive clusters. The obtained results were compared with those of the corresponding gold and hydrogen atom chemisorbed gold clusters obtained at the same level of theory. It is expected the current computational study will provide key insights for future advances in the design of efficient nanosilver-based catalysts through the adsorption of a small atom or a ligand. PMID:25988294

  1. Career Cluster Activity Book, Intermediate Level. Learn About the Fifteen Career Clusters and Color the Pictures.

    ERIC Educational Resources Information Center

    White Hawk, Sharon, Ed.

    Simple black and white illustrations portray one occupation for each of 15 career clusters. Directed toward the Indian student and showing Indians at work in the occupations depicted, the illustrations are intended to create an awareness, understanding, and motivation for Indian students to become involved in work, both on and off the reservation.…

  2. Activation of Methane Promoted by Adsorption of CO on Mo2 C2 (-) Cluster Anions.

    PubMed

    Liu, Qing-Yu; Ma, Jia-Bi; Li, Zi-Yu; Zhao, Chongyang; Ning, Chuan-Gang; Chen, Hui; He, Sheng-Gui

    2016-05-01

    Atomic clusters are being actively studied for activation of methane, the most stable alkane molecule. While many cluster cations are very reactive with methane, the cluster anions are usually not very reactive, particularly for noble metal free anions. This study reports that the reactivity of molybdenum carbide cluster anions with methane can be much enhanced by adsorption of CO. The Mo2 C2 (-) is inert with CH4 while the CO addition product Mo2 C3 O(-) brings about dehydrogenation of CH4 under thermal collision conditions. The cluster structures and reactions are characterized by mass spectrometry, photoelectron spectroscopy, and quantum chemistry calculations, which demonstrate that the Mo2 C3 O(-) isomer with dissociated CO is reactive but the one with non-dissociated CO is unreactive. The enhancement of cluster reactivity promoted by CO adsorption in this study is compared with those of reported systems of a few carbonyl complexes. PMID:27060286

  3. CME for neurosurgeons in the Netherlands: the "quality" conferences.

    PubMed

    Mooij, J J A; Albrecht, K W; Grotenhuis, J A; Zeilstra, D J; Staal, M J; Koot, R W

    2009-02-01

    In 1993 the Netherlands Society for Neurosurgery started a yearly event, a "Quality Conference", specifically devoted to continuous medical education (CME). These conferences differ from "normal" scientific meetings, in the choice for specific topics, in the preparation with inquiries among all the Dutch neurosurgical centres, and in the way the results of these inquiries are discussed, preceded by lectures concerning the chosen topic by guest faculty and Dutch neurosurgeons. Each year's principal guest delivers the "Beks Lecture", named after the former professor in Neurosurgery in Groningen, Jan Beks. On several occasions, the foreign guests suggested to present this format for a larger neurosurgical forum. Therefore, it was decided to describe the various aspects of this format for CME in the Netherlands in a paper for Acta Neurochirugica. Examples of topics are given, a summary of two recent inquiries are presented and discussed, and the way of organizing such a conference including finance and the obligatory character are described. PMID:19194649

  4. Prediction of Type II Radio Bursts Associated with Large CME Events

    NASA Astrophysics Data System (ADS)

    Cairns, Iver; Schmidt, Joachim

    Type II radio bursts are associated with shocks in the corona and solar wind, either driven by CMEs or else by blast waves. Recently we coupled the advanced 3D MHD BATS-R-US code of Toth, Gombosi, and colleagues with our kinetic ``bolt-on'' theory for type II emission. Initialising the simulation code with event specific coronal and CME data, the combined code can be used to predict the dynamic spectrum of type II emission for a specific radio event. We demonstrate very good agreement with Wind spacecraft observations for three type II bursts, one on 15 February 2011 and two on 7 March 2012 (associated with successive CMEs from different sides of the same active region). The intensities, frequencies, and times of fundamental and harmonic type II emission are predicted very well from the high corona to 1 AU (frequencies ~ 20 MHz - 30 kHz). The islands of increased emission correspond to different regions of the shock interacting with coronal structures, with streamers typically corresponding to reduced emission. The results provide strong evidence that both the type II theory and the BATS-R-US (driven with event-specific data) are accurate. They also provide strong evidence that the observation and detailed theoretical modelling of type II bursts can in principle provide warnings with lead-times of over a day for large and fast CMEs that might produce space weather at Earth. The MHD code can also predict whether the CME will hit Earth's magnetopause and the magnetic field direction at the magnetopause as the shock, sheath, and CME, vital quantities for predicting space weather at Earth.

  5. Type II solar radio bursts predicted by 3-D MHD CME and kinetic radio emission simulations

    NASA Astrophysics Data System (ADS)

    Schmidt, J. M.; Cairns, Iver H.

    2014-01-01

    Impending space weather events at Earth are often signaled by type II solar radio bursts. These bursts are generated upstream of shock waves driven by coronal mass ejections (CMEs) that move away from the Sun. We combine elaborate three-dimensional (3-D) magnetohydrodynamic predictions of realistic CMEs near the Sun with a recent analytic kinetic radiation theory in order to simulate two type II bursts. Magnetograms of the Sun are used to reconstruct initial solar magnetic and active region fields for the modeling. STEREO spacecraft data are used to dimension the flux rope of the initial CME, launched into an empirical data-driven corona and solar wind. We demonstrate impressive accuracy in time, frequency, and intensity for the two type II bursts observed by the Wind spacecraft on 15 February 2011 and 7 March 2012. Propagation of the simulated CME-driven shocks through coronal plasmas containing preexisting density and magnetic field structures that stem from the coronal setup and CME initiation closely reproduce the isolated islands of type II emission observed. These islands form because of a competition between the growth of the radio source due to spherical expansion and a fragmentation of the radio source due to increasingly radial fields in the nose region of the shock and interactions with streamers in the flank regions of the shock. Our study provides strong support for this theory for type II bursts and implies that the physical processes involved are understood. It also supports a near-term capability to predict and track these events for space weather predictions.

  6. Coronal Magnetic Field Measurement Using CME-Driven Shock Observations

    NASA Technical Reports Server (NTRS)

    Gopalswarmy, Nat; Nitta, N.; Yashiro, S.; Makela, P.; Xie, H.; Akiyama, S.

    2012-01-01

    Collisionless shocks form ahead of coronal mass ejections (CMEs) when the CME speed exceeds the Alfven speed of the ambient plasma in the corona and interplanetary medium. The shock stands at a distance from the CME flux rope that depends on the shock Mach number, the geometry of the driver, and the adiabatic index. While the shock ahead of the CME has been observed for a long time in the in situ data, it has been identified recently near the Sun in the coronagraphic and EUV images. Unlike in situ observations, the imaging observations are two dimensional, so one can better discern the CME-shock relationship near the Sun. Gopalswamy and Yashiro demonstrated that the coronal magnetic field can be derived from the shock standoff distance measured in coronagraphic images. The method involves measuring the standoff distance, the radius of curvature of the flux rope, and assuming the value of the adiabatic index and deriving the Alfvenic Mach number. The next step is to derive the Alfvenic Mach number from the measured shock speed and an estimate of the local solar wind speed. The final step involves deriving the magnetic field from the Alfven speed by measuring the local plasma density either from coronagraphic (polarized brightness) images or from the band-splitting of type II radio bursts. In this paper, we derive the combined magnetic field profile from near the Sun to the edge of the LASCO field of view (1.5 to 30 solar radii) and compare it with the current model profiles.

  7. The New CME: Focus Shifts to Improving Physician Performance.

    PubMed

    Ortolon, Ken

    2010-10-01

    The traditional method of physicians earning continuing medical education credits by attending a lecture or case conference, watching a webinar, or reading a journal article is being replaceed with performance improvement CME. Requiring a much greater level of physician involvement, it involves chart audits to measure current physician performance, followed by an intervention to change physician behavior. Performance is then remeasured to gauge the level of improvement. PMID:20890801

  8. Type II Radio Bursts as an Indicator of CME Location

    NASA Astrophysics Data System (ADS)

    Quirk, C. A.; St Cyr, O. C.; Henning, C.; Xie, H.; Gilbert, H. R.; Orlove, M.; Gopalswamy, N.; Odstrcil, D.

    2011-12-01

    We examined a subset of nine low-frequency radio events with type II radio bursts that drifted below 2 megahertz and were detected by the WAVES investigation on the WIND spacecraft. For each event, we identified the associated coronal mass ejection (CME) and derived the electron density using a model of solar wind plasma frequency (fp ≈ 9 * ne1/2, where fp is plasma frequency in kHz and ne is electron density in cm-3) . We also used the pb_inverter program in SolarSoft developed by Howard and Hayes to examine the electron density structure. Expanding on the Van De Hulst process of inverting polarized brightness measurements, the program inverts total brightness measurements from SOHO LASCO images to extract electron density information. From the electron density inferred from radio spectra, we derived the location of the CME using five standard electron density to height models (Leblanc, 1996; Saito, 1977; Bougeret, 1984; Alvarez, 1973; and Fainberg, 1971). Using images from the LASCO instrument on SOHO and the SECCHI instrument on STEREO, we extracted locations of the leading edge of the CME and compared the heights and velocities to those found using the frequency data. For the lowest frequency events, we also compared our results to the outputs of ENLIL, a time-dependent, three-dimensional, MHD model of the heliosphere hosted by the Community Coordinated Modeling Center (CCMC) at NASA Goddard Space Flight Center.

  9. A cluster expansion model for predicting activation barrier of atomic processes

    SciTech Connect

    Rehman, Tafizur; Jaipal, M.; Chatterjee, Abhijit

    2013-06-15

    We introduce a procedure based on cluster expansion models for predicting the activation barrier of atomic processes encountered while studying the dynamics of a material system using the kinetic Monte Carlo (KMC) method. Starting with an interatomic potential description, a mathematical derivation is presented to show that the local environment dependence of the activation barrier can be captured using cluster interaction models. Next, we develop a systematic procedure for training the cluster interaction model on-the-fly, which involves: (i) obtaining activation barriers for handful local environments using nudged elastic band (NEB) calculations, (ii) identifying the local environment by analyzing the NEB results, and (iii) estimating the cluster interaction model parameters from the activation barrier data. Once a cluster expansion model has been trained, it is used to predict activation barriers without requiring any additional NEB calculations. Numerical studies are performed to validate the cluster expansion model by studying hop processes in Ag/Ag(100). We show that the use of cluster expansion model with KMC enables efficient generation of an accurate process rate catalog.

  10. Deriving Age-Activity Relations in M Dwarf Stars Using Clusters of Known Ages

    NASA Astrophysics Data System (ADS)

    Andersen, J. M.; West, A. A.; Covey, K. R.; McDonald, M.; Veilleux, S.; Seth, A.

    2011-12-01

    We present preliminary results from a study of M dwarf magnetic activity in clusters of known ages with the ultimate goal of constraining the age-activity relation. The age-activity relation provides clues to the mechanisms generating magnetic dynamos, especially in late-type dwarfs where their stellar interiors become fully convective. Broadband griz photometry was obtained for four clusters with ages ranging from ˜110 Myrs to 4 Gyrs. Narrowband images of each cluster were acquired with the Maryland Magellan Tunable Filter, tuned to the frequency of Hα, including a correction for the cluster's radial velocity, and a nearby, similarly sized bandpass sampling the stellar pseudo-continuum. This permits a "photometric" measurement of the Hα emission for each star, and thus a measure of activity. Cluster membership is determined from broadband photometry and comparison to stellar positions from previous studies. We report on our findings for the cluster NGC 2516. Hα measurements are stronger for cluster stars than for field stars of the same magnitude. A clear correlation is seen between our Hα strengths measured by narrowband imaging and previous spectroscopic activity measurements for stars where spectra have been obtained.

  11. X-Ray Activity in the Open Cluster IC 4665

    NASA Technical Reports Server (NTRS)

    Giamapapa, Mark S.; Prosser, Charles F.; Fleming, Thomas A.

    1997-01-01

    We present the results of a joint ROSAT High Resolution Imager (HRI) and optical investigation of the open cluster IC 4665. The ROSAT data contains detections for 28 stellar sources in the field, including 22 cluster members and candidate members spanning the color range -0.18 less than or equal to (B - V(sub o)) less than or equal to +1.63 (approx. B3 - M3). Upper limits are given for the remaining members (or candidate members) in the HRI field. Keck HIRES spectra have been obtained that yield radial and rotational velocity measures, respectively, for faint, low mass candidate members located within the field of the ROSAT HRI observation. In addition, photometry of possible optical counterparts to previously uncatalogued X-ray sources in the HRI field is presented. The trends in X-ray properties with (B - V) color in IC 4665 are found to be quite similar to that for other, more nearby young clusters such as the Pleiades and alpha Persei. In particular, a maximum in normalized X-ray luminosity of log (L(sub x)/L(sub bol)) approx. equal 3 is observed, beginning in the color range of (B - V)(sub o) = 0.7 - 0.8. This is similar to the corresponding color range among Pleiades members, in agreement with the earlier estimate, that the age of IC 4665 is similar to the age of the Pleiades. The correlation of rotation and X-ray emission levels is consistent with that in other young clusters. Among the high mass stars in IC 4665, five B stars are detected as X-ray sources. Of these, one is a spectroscopic binary while the remaining objects are apparently single staxs. The level of intrinsic X-ray emission observed in the rapidly rotating (v sini greater than 200 km/ s), single B stars is consistent with an origin due to shock heating of the ambient medium by radiatively driven, rotationally enhanced winds. On the basis of these observations and the results for other clusters, we argue that observed levels of X-ray emission in high mass stars of log (L(sub x)/L(sub bol

  12. MHD simulations for investigating interaction processes between a CME and ambient solar wind

    NASA Astrophysics Data System (ADS)

    An, Junmo; Magara, Tetsuya

    2016-05-01

    The interaction between coronal mass ejections (CMEs) and ambient solar winds is one of the important issues of space weather because it affects the trajectory of a flying CME, which determines whether the CME hits the Earth and produces geomagnetic disturbances or not. In this study, two-step 3D magnetohydrodynamic (MHD) simulations including a spheromak-type CME and an ambient solar wind are performed to investigate their interaction processes such as deflection and rotation of a CME. We perform the 1st-step MHD simulation using averaged surface magnetic field data to construct a steady state with an ambient solar wind. A spheromak-type CME is then injected through the solar surface, and subsequent evolution is reproduced by performing the 2nd-step MHD simulation. We discuss key parameters that characterize interaction processes between a CME and ambient solar wind.

  13. STUDY OF THE 2007 APRIL 20 CME-COMET INTERACTION EVENT WITH AN MHD MODEL

    SciTech Connect

    Jia, Y. D.; Russell, C. T.; Jian, L. K.; Manchester, W. B.; Cohen, O.; Hansen, K. C.; Combi, M. R.; Gombosi, T. I.; Vourlidas, A.

    2009-05-01

    This study examines the tail disconnection event on 2007 April 20 on comet 2P/Encke, caused by a coronal mass ejection (CME) at a heliocentric distance of 0.34 AU. During their interaction, both the CME and the comet are visible with high temporal and spatial resolution by the STEREO-A spacecraft. Previously, only current sheets or shocks have been accepted as possible reasons for comet tail disconnections, so it is puzzling that the CME caused this event. The MHD simulation presented in this work reproduces the interaction process and demonstrates how the CME triggered a tail disconnection in the April 20 event. It is found that the CME disturbs the comet with a combination of a 180 deg. sudden rotation of the interplanetary magnetic field (IMF), followed by a 90 deg. gradual rotation. Such an interpretation applies our understanding of solar wind-comet interactions to determine the in situ IMF orientation of the CME encountering Encke.

  14. Evolution and Distribution of Magnetic Fields from Active Galactic Nuclei in Galaxy Clusters. II. The Effects of Cluster Size and Dynamical State

    NASA Astrophysics Data System (ADS)

    Xu, Hao; Li, Hui; Collins, David C.; Li, Shengtai; Norman, Michael L.

    2011-10-01

    Theory and simulations suggest that magnetic fields from radio jets and lobes powered by their central super massive black holes can be an important source of magnetic fields in the galaxy clusters. This is Paper II in a series of studies where we present self-consistent high-resolution adaptive mesh refinement cosmological magnetohydrodynamic simulations that simultaneously follow the formation of a galaxy cluster and evolution of magnetic fields ejected by an active galactic nucleus. We studied 12 different galaxy clusters with virial masses ranging from 1 × 1014 to 2 × 1015 M sun. In this work, we examine the effects of the mass and merger history on the final magnetic properties. We find that the evolution of magnetic fields is qualitatively similar to those of previous studies. In most clusters, the injected magnetic fields can be transported throughout the cluster and be further amplified by the intracluster medium (ICM) turbulence during the cluster formation process with hierarchical mergers, while the amplification history and the magnetic field distribution depend on the cluster formation and magnetism history. This can be very different for different clusters. The total magnetic energies in these clusters are between 4 × 1057 and 1061 erg, which is mainly decided by the cluster mass, scaling approximately with the square of the total mass. Dynamically older relaxed clusters usually have more magnetic fields in their ICM. The dynamically very young clusters may be magnetized weakly since there is not enough time for magnetic fields to be amplified.

  15. Coordination and activation of azetidine by a triosmium cluster

    SciTech Connect

    Adams, R.D.; Chen, G. )

    1993-06-01

    The ring opening of nitrogen-containing heterocycles is an integral step in the process of hydrogenitrogenatio. The mechanisms by which this step occurs are poorly understood; thus a considerable amount of research has been devoted to modeling this heterogeneous reaction by using homogeneous catalysts. Although it has considerable ring strain, the four-membered heterocycle, azetidine, is opened thermally only at temperatures in excess of 400[degrees]C. Recently, we have found that thietanes, the saturated four-membered heterocycles containing sulfur, undergo facile ring opening when the molecule is coordinated to osmium cluster complexes. It was shown that a bridging coordination of the sulfur atom promotes this process. Thus, we wondered if it might also be possible to open an azetidine ring in a cluster complex under conditions sufficiently mild that a detailed study of the process might be possible. We have now prepared an osmium cluster complex in which the nitrogen atom of the azetidine ligand bridges two of the metal atoms, and we have found that the azetidine ring is spontaneously opened when the complex is heated to 125[degrees]C. In addition, two other complexes formed by transformation of the azetidine ligand have been isolated and characterized. The results of this study are reported here. 20 refs., 4 figs., 13 tabs.

  16. Crystal Structure of the Transcriptional Regulator CmeR From Campylobacter Jejuni

    SciTech Connect

    Gu, R.; Su, C.-C.; Shi, F.; McDermott, G.; Zhang, Q.; Yu, E.W.

    2009-06-01

    The CmeABC multidrug efflux pump, which belongs to the resistance-nodulation-division (RND) family, recognizes and extrudes a broad range of antimicrobial agents and is essential for Campylobacter jejuni colonization of the animal intestinal tract by mediating the efflux of bile acids. The expression of CmeABC is controlled by the transcriptional regulator CmeR, whose open reading frame is located immediately upstream of the cmeABC operon. To understand the structural basis of CmeR regulation, we have determined the crystal structure of CmeR to 2.2 {angstrom} resolution, revealing a dimeric two-domain molecule with an entirely helical architecture similar to members of the TetR family of transcriptional regulators. Unlike the rest of the TetR regulators, CmeR has a large center-to-center distance (54 {angstrom}) between two N termini of the dimer, and a large flexible ligand-binding pocket in the C-terminal domain. Each monomer forms a 20 {angstrom} long tunnel-like cavity in the ligand-binding domain of CmeR and is occupied by a fortuitous ligand that is identified as glycerol. The binding of glycerol to CmeR induces a conformational state that is incompatible with target DNA. As glycerol has a chemical structure similar to that of potential ligands of CmeR, the structure obtained mimics the induced form of CmeR. These findings reveal novel structural features of a TetR family regulator, and provide new insight into the mechanisms of ligand binding and CmeR regulation.

  17. Thermal Dihydrogen Activation by a Closed-Shell AuCeO2(+) Cluster.

    PubMed

    Meng, Jing-Heng; He, Sheng-Gui

    2014-11-01

    Laser-ablation-generated AuCeO2(+) and CeO2(+) oxide clusters were mass-selected using a quadrupole mass filter and reacted with H2 in an ion trap reactor at ambient conditions. The reactions were characterized by mass spectrometry and density functional theory calculations. The gold-cerium bimetallic oxide cluster AuCeO2(+) is more reactive in H2 activation than the pure cerium oxide cluster CeO2(+). The gold atom is the active adsorption site and facilitates the heterolytic cleavage of H2 in collaboration with the separated O(2-) ion of the CeO2 support. To the best of our knowledge, this is the first example of thermal H2 activation by a closed-shell atomic cluster, which provides molecular-level insights into the single gold atom catalysis over metal oxide supports. PMID:26278765

  18. Particle Acceleration by Cme-driven Shock Waves

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    1999-01-01

    In the largest solar energetic particle (SEP) events, acceleration occurs at shock waves driven out from the Sun by coronal mass ejections (CMEs). Peak particle intensities are a strong function of CME speed, although the intensities, spectra, and angular distributions of particles escaping the shock are highly modified by scattering on Alfven waves produced by the streaming particles themselves. Element abundances vary in complex ways because ions with different values of Q/A resonate with different parts of the wave spectrum, which varies with space and time. Just recently, we have begun to model these systematic variations theoretically and to explore other consequences of proton-generated waves.

  19. Scientific goals of the Cooperative Multiscale Experiment (CME)

    NASA Technical Reports Server (NTRS)

    Cotton, William

    1993-01-01

    Mesoscale Convective Systems (MCS) form the focus of CME. Recent developments in global climate models, the urgent need to improve the representation of the physics of convection, radiation, the boundary layer, and orography, and the surge of interest in coupling hydrologic, chemistry, and atmospheric models of various scales, have emphasized the need for a broad interdisciplinary and multi-scale approach to understanding and predicting MCS's and their interactions with processes at other scales. The role of mesoscale systems in the large-scale atmospheric circulation, the representation of organized convection and other mesoscale flux sources in terms of bulk properties, and the mutually consistent treatment of water vapor, clouds, radiation, and precipitation, are all key scientific issues concerning which CME will seek to increase understanding. The manner in which convective, mesoscale, and larger scale processes interact to produce and organize MCS's, the moisture cycling properties of MCS's, and the use of coupled cloud/mesoscale models to better understand these processes, are also major objectives of CME. Particular emphasis will be placed on the multi-scale role of MCS's in the hydrological cycle and in the production and transport of chemical trace constituents. The scientific goals of the CME consist of the following: understand how the large and small scales of motion influence the location, structure, intensity, and life cycles of MCS's; understand processes and conditions that determine the relative roles of balanced (slow manifold) and unbalanced (fast manifold) circulations in the dynamics of MCS's throughout their life cycles; assess the predictability of MCS's and improve the quantitative forecasting of precipitation and severe weather events; quantify the upscale feedback of MCS's to the large-scale environment and determine interrelationships between MCS occurrence and variations in the large-scale flow and surface forcing; provide a data base

  20. Validation of a global 3D heliospheric model with observations for the May 12, 1997 CME event

    NASA Astrophysics Data System (ADS)

    Cohen, O.; Sokolov, I. V.; Roussev, I. I.; Lugaz, N.; Manchester, W. B.; Gombosi, T. I.; Arge, C. N.

    2008-02-01

    We simulate the May 12, 1997 space weather event from the Sun to the Earth. The initiation of the coronal mass ejection (CME) was done by superimposing a semi-circular, out-of-equilibrium magnetic flux rope onto a semi-empirical, steady-state solar corona model (SCM). The result at 1 AU was obtained by coupling the SCM with an inner heliosphere model (IHM). Our results demonstrate that the CME parameters can be obtained from magnetogram data and white-light observations and that the results at 1 AU can be simulated faster than the real time, even with the use of a relatively moderate computation resources. This particular event, however, is found to be very difficult to model, despite the fact that it is temporarily isolated in time from other CME events and it occurred during a solar minimum period. We found that the active region flux rope should be resolved with higher resolution in order to maintain its integrity while propagating into space. This way we can obtain a better agreement with measurements at 1 AU.

  1. Communication: CO oxidation by silver and gold cluster cations: Identification of different active oxygen species

    SciTech Connect

    Popolan, Denisia M.; Bernhardt, Thorsten M.

    2011-03-07

    The oxidation of carbon monoxide with nitrous oxide on mass-selected Au{sub 3}{sup +} and Ag{sub 3}{sup +} clusters has been investigated under multicollision conditions in an octopole ion trap experiment. The comparative study reveals that for both gold and silver cations carbon dioxide is formed on the clusters. However, whereas in the case of Au{sub 3}{sup +} the cluster itself acts as reactive species that facilitates the formation of CO{sub 2} from N{sub 2}O and CO, for silver the oxidized clusters Ag{sub 3}O{sub x}{sup +} (n= 1-3) are identified as active in the CO oxidation reaction. Thus, in the case of the silver cluster cations N{sub 2}O is dissociated and one oxygen atom is suggested to directly react with CO, whereas a second kind of oxygen strongly bound to silver is acting as a substrate for the reaction.

  2. The Relationship between Cortisol Activity during Cognitive Task and Posttraumatic Stress Symptom Clusters

    PubMed Central

    Duan, Hongxia; Wang, Li; Zhang, Liang; Liu, Jing; Zhang, Kan; Wu, Jianhui

    2015-01-01

    Background The latest development in the dimensional structure of posttraumatic stress disorder (PTSD) is a novel 6-factor model, which builds on the newly released DSM-5. One notable gap in the literature is that little is known about how distinct symptom clusters of PTSD are related to hypothalamic–pituitary–adrenal (HPA) axis activity when people perform a relatively less stressful cognitive task. The purpose of this study was to investigate the relationship between cortisol activity when individuals perform cognitive tasks in the laboratory and a contemporary phenotypic model of posttraumatic stress symptomatology in earthquake survivors. Methods Salivary cortisol while performing cognitive tasks was collected and analyzed in 89 adult earthquake survivors. The PTSD Checklist for the DSM-5 (PCL-5) was used to assess the severity of total PTSD as well as six distinct symptom clusters. Regression analyses were conducted to examine the associations between the six distinct PTSD symptom clusters and cortisol profiles. Results The results showed that the score of the negative affect symptom cluster, but not anhedonia or other clusters, was positively associated with cortisol levels before and during the cognitive tasks. Conclusion The results showed that higher cortisol levels before and during cognitive tasks might be specifically linked to a distinct symptom cluster of PTSD—negative affect symptomatology. This suggests that a distinction should be made between negative affect and anhedonia symptom clusters, as the 6-factor model proposed. PMID:26630485

  3. Identification of clusters of investors from their real trading activity in a financial market

    NASA Astrophysics Data System (ADS)

    Tumminello, Michele; Lillo, Fabrizio; Piilo, Jyrki; Mantegna, Rosario N.

    2012-01-01

    We use statistically validated networks, a recently introduced method of validating links in a bipartite system, to identify clusters of investors trading in a financial market. Specifically, we investigate a special database allowing us to track the trading activity of individual investors of Nokia stock. We find that many statistically detected clusters of investors show a very high degree of synchronization in time when they decide to trade and in the trading action taken. We investigate the composition of these clusters and find that several of them show an over-expression of specific categories of investors.

  4. AWM 4: a sharp look at the core of a poor cluster stirred by AGN activity

    NASA Astrophysics Data System (ADS)

    Vrtilek, Jan

    2007-09-01

    The central regions of galaxy clusters, frequently occupied by massive elliptical galaxies with strong radio sources interacting with dense, X-ray emitting gas, are among the most interesting and physically active regions in the Universe. We here propose a deep observation of AWM 4, a poor cluster of relaxed appearance without a cooling core but with strong evidence of AGN-driven heating and gas mixing. In this unusual object we will examine the interaction between cluster gas and radio source at high resolution, measure the properties of the gas and constrain the energy budget of the radio source, and clarify the nature of the observed abundance irregularities.

  5. Nitric oxide synthases activation and inhibition by metallacarborane cluster-based isoform-specific affectors

    PubMed Central

    Kaplánek, Robert; Martásek, Pavel; Grüner, Bohumír; Panda, Satya; Rak, Jakub; Masters, Bettie Sue Siler; Král, Vladimír; Roman, Linda J.

    2012-01-01

    A small library of boron cluster and metallacarborane cluster-based ligands was designed, prepared and tested for isoform-selective activation or inhibition of the three nitric oxide synthase isoforms. Based on the concept of creating a hydrophobic analog of a natural substrate, a stable and non-toxic basic boron cluster system, previously used for boron neutron capture therapy, was modified by the addition of positively charged moieties to its periphery, providing hydrophobic and non-classical hydrogen bonding interactions with the protein. Several of these compounds show efficacy for inhibition of NO synthesis with differential effects on the various nitric oxide synthase isoforms. PMID:23075390

  6. Cluster Analysis of the Rat Olfactory Bulb Activity in Response to Different Odorants

    NASA Astrophysics Data System (ADS)

    Falasconi, M.; Gutierrez, A.; Auffarth, B.; Sberveglieri, G.; Marco, S.

    2009-05-01

    With the goal of deepen in the understanding of coding of chemical information in the olfactory system, a large data set consisting of rat's olfactory bulb activity values in response to several different volatile compounds has been analyzed by fuzzy c-means clustering methods. Clustering should help to discover groups of glomeruli that are similary activated according to their response profiles across the odorants. To investigate the significance of the achieved fuzzy partitions we developed and applied a novel validity approach based on cluster stability. Our results show certain level of glomerular clustering in the olfactory bulb and indicate that exist a main chemo-topic subdivision of the glomerular layer in few macro-area which are rather specific to particular functional groups of the volatile molecules.

  7. Effect on the Lunar Exosphere of a CME Passage

    NASA Technical Reports Server (NTRS)

    Killen, Roseamry M.; Hurley, Dana M.; Farrell, William M.; Sarantos, Menelaos

    2011-01-01

    It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that the sputter yield can be noticeably increased in the case of a good insulating surface. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind. fast wind. solar energetic particle (SEP) population. and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. The heavy ion component, especially the He(++) component, greatly enhances the total sputter yield during times when the heavy ion population is enhanced, most notably during a coronal mass ejection. To simulate the etfect on the lunar exosphere of a CME passage past the Moon, we ran a Monte Carlo code for the species Na, K, Mg and Ca.

  8. Effect on the Lunar Exosphere of a CME Passage

    NASA Technical Reports Server (NTRS)

    Killen, Rosemary M.; Hurley, Dana M.; Farrell, William M.; Sarantos, Menelaos

    2011-01-01

    It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that the sputter yield can be noticeably increased in the case of a good insulating surface. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. The heavy ion component, especially the He++ component, greatly enhances the total sputter yield during times when the heavy ion population is enhanced, most notably during a coronal mass ejection. To simulate the effect on the lunar exosphere of a CME passage past the Moon, we ran a Monte Carlo code for the species Na, K, Mg and Ca.

  9. Morphology and Density Structure of Post-CME Current Sheets

    NASA Technical Reports Server (NTRS)

    Vrsnak, B.; Poletto, G.; Vujic, E.; Vourlidas, A.

    2009-01-01

    Eruption of a coronal mass ejection (CME) is believed to drag and open the coronal magnetic field, presumably leading to the formation of a large-scale current sheet and field relaxation by magnetic reconnection. This paper analyzes the physical characteristics of ray-like coronal features formed in the aftermath of CMEs, to confirm whether interpreting such phenomena in terms of a reconnecting current sheet is consistent with observations. Methods: The study focuses on UVCS/SOHO and LASCO/SOHO measurements of the ray width, density excess, and coronal velocity field as a function of the radial distance. The morphology of the rays implies that they are produced by Petschek-like reconnection in the large-scale current sheet formed in the wake of CME. The hypothesis is supported by the flow pattern, often showing outflows along the ray, and sometimes also inflows into the ray. The inferred inflow velocities range from 3 to 30 km/s, and are consistent with the narrow opening-angle of rays, which add up to a few degrees. The density of rays is an order of magnitude higher than in the ambient corona. The model results are consistent with the observations, revealing that the main cause of the density excess in rays is a transport of the dense plasma from lower to higher heights by the reconnection outflow.

  10. Acceleration of SEPs in Flaring Loops and CME Driven shocks

    NASA Astrophysics Data System (ADS)

    Petrosian, Vahe; Chen, Qingrong

    2014-06-01

    We consider two stage acceleration of the Solar Energetic Particles (SEPs). The first occurring via the stochastic acceleration mechanism at the flare site in the corona, which produces the so-called impulsive SEPs, with anomalous abundances, as well as nonthermal particles responsible for the observed radiation. The second is re-acceleration the flare accelerated particles at the CME driven shock associated with larger, longer duration events with relatively normal abundances. Turbulence plays a major role in both stages. We will show how stochastic acceleration can explain some of the salient features of the impulsive SEP observations; such as extreme enrichment of 3He (and heavy ions), and the observed broad distributions and ranges of the 3He and 4He fluences. We will then show that the above hybrid mechanism of first stochastic acceleration of ions in the reconnecting coronal magnetic structures and then their re-acceleration in the CME shock can produce the varied shapes of the 3He and 4He spectra observed in all events ranging from weak impulsive to strong gradual events.

  11. SEP acceleration in CME driven shocks using a hybrid code

    SciTech Connect

    Gargaté, L.; Fonseca, R. A.; Silva, L. O.

    2014-09-01

    We perform hybrid simulations of a super-Alfvénic quasi-parallel shock, driven by a coronal mass ejection (CME), propagating in the outer coronal/solar wind at distances of between 3 to 6 solar radii. The hybrid treatment of the problem enables the study of the shock propagation on the ion timescale, preserving ion kinetics and allowing for a self-consistent treatment of the shock propagation and particle acceleration. The CME plasma drags the embedded magnetic field lines stretching from the sun, and propagates out into interplanetary space at a greater velocity than the in situ solar wind, driving the shock, and producing very energetic particles. Our results show that electromagnetic Alfvén waves are generated at the shock front. The waves propagate upstream of the shock and are produced by the counter-streaming ions of the solar wind plasma being reflected at the shock. A significant fraction of the particles are accelerated in two distinct phases: first, particles drift from the shock and are accelerated in the upstream region, and second, particles arriving at the shock get trapped and are accelerated at the shock front. A fraction of the particles diffused back to the shock, which is consistent with the Fermi acceleration mechanism.

  12. CME dynamics using coronagraph and interplanetary ejecta observations

    NASA Astrophysics Data System (ADS)

    Dal Lago, Alisson; Demítrio Gonzalez Alarcon, Walter; da Silva, Marlos; de Lucas, Aline; Braga, Carlos Roberto; Ramos Vieira, Lucas

    One of the key issues of Space Weather is the dynamics of coronal mass ejections, from their release from the Sun, their propagation throughout the interplanetary space, eventually im-pacting the earth and other planets. These impacts of CMEs are the most important drivers of space weather phenomena. A number of empirical and analytical studies have addressed this point so far, using observations from coronagraphs and interplanetary monitors, in order to correlate CMEs observed near the Sun and in situ (e.g. earth vincity). However, results are far from conclusive. Error bars in CME travel time predictions from the Sun to earth, are of the order of 1 day, which is considerably big for the typical time scale of 1 to 3 days of their travel time. After many years of intensive investigations of CMEs observed with the Large An-gle and Spectrometric Coronagraph (LASCO), abord the Solar and Heliospheric Observatory (SOHO), we found that the subset of interplanetary counterparts of CMEs, the ICMEs, with a well defined ejecta structure are those with best predictable behaviour. The prediction of these interplanetary ejecta travel time to earth, using coronagraph observations is the one with lowest error bar among other sets of events, such as interplanetary shock. We present a statistic study of all the CME-ejecta events observed by SOHO and by the Advanced Composition Explorer (ACE) satellite since 1997.

  13. Quantitative Analysis of CME Deflections in the Corona

    NASA Astrophysics Data System (ADS)

    Gui, Bin; Shen, Chenglong; Wang, Yuming; Ye, Pinzhong; Liu, Jiajia; Wang, Shui; Zhao, Xuepu

    2011-07-01

    In this paper, ten CME events viewed by the STEREO twin spacecraft are analyzed to study the deflections of CMEs during their propagation in the corona. Based on the three-dimensional information of the CMEs derived by the graduated cylindrical shell (GCS) model (Thernisien, Howard, and Vourlidas in Astrophys. J. 652, 1305, 2006), it is found that the propagation directions of eight CMEs had changed. By applying the theoretical method proposed by Shen et al. ( Solar Phys. 269, 389, 2011) to all the CMEs, we found that the deflections are consistent, in strength and direction, with the gradient of the magnetic energy density. There is a positive correlation between the deflection rate and the strength of the magnetic energy density gradient and a weak anti-correlation between the deflection rate and the CME speed. Our results suggest that the deflections of CMEs are mainly controlled by the background magnetic field and can be quantitatively described by the magnetic energy density gradient (MEDG) model.

  14. Star formation and black hole accretion activity in rich local clusters of galaxies

    NASA Astrophysics Data System (ADS)

    Bianconi, Matteo; Marleau, Francine R.; Fadda, Dario

    2016-04-01

    Context. We present a study of star formation and central black hole accretion activity of galaxies that are hosted in the two nearby (z ~ 0.2) rich galaxy clusters Abell 983 and 1731. Aims: We aim to quantify both the obscured and unobscured star formation rates, as well as the presence of active galactic nuclei (AGN) as a function of the environment in which the galaxy is located. Methods: We targeted the clusters with unprecedented deep infrared Spitzer observations (0.2 mJy at 24 micron), near-IR Palomar imaging and optical WIYN spectroscopy. The extent of our observations (~3 virial radii) covers the vast range of possible environments, from the very dense cluster centre to the very rarefied cluster outskirts and accretion regions. Results: The star-forming members of the two clusters present star formation rates that are comparable with those measured in coeval field galaxies. Analysis of the spatial arrangement of the spectroscopically confirmed members reveals an elongated distribution for A1731 with respect to the more uniform distribution of A983. The emerging picture is compatible with A983 being a fully evolved cluster, in contrast with the still actively accreting A1731. Conclusions: Analysis of the specific star formation rate reveals evidence of ongoing galaxy pre-processing along A1731's filament-like structure. Furthermore, the decrease in the number of star-forming galaxies and AGN towards the cluster cores suggests that the cluster environment is accelerating the ageing process of the galaxies and blocking further accretion of the cold gas that fuels both star formation and black hole accretion activity. The catalogue and the reduced images (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A105

  15. An Intense Flare-CME Event in 2015: Propagation and Interaction Effects Between the Sun and Earth's Orbit

    NASA Astrophysics Data System (ADS)

    Johri, Abhishek; Manoharan, P. K.

    2016-05-01

    We report the interplanetary effects of a fast coronal mass ejection (CME) associated with the intense X2.7 flare that occurred on 05 May 2015. The near-Sun signatures of the CME at low-coronal heights [ {<} 2 R_{⊙}] are obtained from the EUV images at 171 Å and metric radio observations. The intensity and duration of the CME-driven radio bursts in the near-Sun and interplanetary medium indicate this CME event to be an energetic one. The interplanetary-scintillation data, along with the low-frequency radio spectrum, played a crucial role in understanding the radial evolution of the speed and expansion of the CME in the inner heliosphere as well as its interaction with a preceding slow CME. The estimation of the speed of the CME at several points along the Sun to 1 AU trajectory shows that: i) the CME went through a rapid acceleration as well as expansion up to a height of {≈} 6 R_{⊙}, and ii) the CME continued to propagate at speed {≥} 800 k} s^{-1} between the Sun and 1 AU. These results show that the CME likely overcame the drag exerted by the ambient/background solar wind with the support of its internal magnetic energy. When the CME interacted with a slow, preceding CME, the turbulence level associated with the CME-driven disturbance increased significantly.

  16. An Intense Flare-CME Event in 2015: Propagation and Interaction Effects Between the Sun and Earth's Orbit

    NASA Astrophysics Data System (ADS)

    Johri, Abhishek; Manoharan, P. K.

    2016-05-01

    We report the interplanetary effects of a fast coronal mass ejection (CME) associated with the intense X2.7 flare that occurred on 05 May 2015. The near-Sun signatures of the CME at low-coronal heights [{<} 2 R_{⊙}] are obtained from the EUV images at 171 Å and metric radio observations. The intensity and duration of the CME-driven radio bursts in the near-Sun and interplanetary medium indicate this CME event to be an energetic one. The interplanetary-scintillation data, along with the low-frequency radio spectrum, played a crucial role in understanding the radial evolution of the speed and expansion of the CME in the inner heliosphere as well as its interaction with a preceding slow CME. The estimation of the speed of the CME at several points along the Sun to 1 AU trajectory shows that: i) the CME went through a rapid acceleration as well as expansion up to a height of {≈} 6 R_{⊙}, and ii) the CME continued to propagate at speed {≥} 800 km s^{-1} between the Sun and 1 AU. These results show that the CME likely overcame the drag exerted by the ambient/background solar wind with the support of its internal magnetic energy. When the CME interacted with a slow, preceding CME, the turbulence level associated with the CME-driven disturbance increased significantly.

  17. A Reflective Learning Framework to Evaluate CME Effects on Practice Reflection

    ERIC Educational Resources Information Center

    Leung, Kit H.; Pluye, Pierre; Grad, Roland; Weston, Cynthia

    2010-01-01

    Introduction: The importance of reflective practice is recognized by the adoption of a reflective learning model in continuing medical education (CME), but little is known about how to evaluate reflective learning in CME. Reflective learning seldom is defined in terms of specific cognitive processes or observable performances. Competency-based…

  18. Promoting Free Online CME for Intimate Partner Violence: What Works at What Cost?

    ERIC Educational Resources Information Center

    Harris, John M., Jr.; Novalis-Marine, Cheryl; Amend, Robert W.; Surprenant, Zita J.

    2009-01-01

    Introduction: There is a need to provide practicing physicians with training on the recognition and management of intimate partner violence (IPV). Online continuing medical education (CME) could help meet this need, but there is little information on the costs and effectiveness of promoting online CME to physicians. This lack of information may…

  19. Effect of CME on Primary Care and OB/GYN Treatment of Breast Masses

    ERIC Educational Resources Information Center

    Price, David W.; Xu, Stanley; McClure, David

    2005-01-01

    Introduction: CME program planners are being asked to move beyond assessments of knowledge to assessing the impact of CME on practice and patient outcomes. Methods: We conducted a pre-post analysis of administrative data from 107 physicians, nurse practitioners (NPs), or physician's assistants (PAs) who attended one or two continuing medical…

  20. Preliminary structural studies of the transcriptional regulator CmeR from Campylobacter jejuni

    SciTech Connect

    Su, Chih-Chia; Shi, Feng; Gu, Ruoyu; Li, Ming; McDermott, Gerry; Yu, Edward W.; Zhang, Qijing

    2007-01-01

    The transcriptional regulator CmeR from C. jejuni has been purified and crystallized and X-ray diffraction data have been collected to a resolution of 2.2 Å. In Campylobacter jejuni, a Gram-negative bacterial pathogen causing gastroenteritis in humans, the CmeR regulatory protein controls transcription of the multidrug transporter gene operon cmeABC. CmeR belongs to the TetR family of transcriptional regulators. The 210-residue CmeR consists of two functional motifs: an N-terminal DNA-binding domain and a C-terminal ligand-binding domain. It is predicted that the DNA-binding domain interacts directly with target promoters, while the C-terminal motif interacts with inducing ligands (such as bile salts). As an initial step towards confirming this structural model, recombinant CmeR protein containing a 6×His tag at the N-terminus was crystallized. Crystals of ligand-free CmeR belonged to space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 37.4, b = 57.6, c = 93.3 Å. Diffraction was observed to at least 2.2 Å at 100 K. Analysis of the detailed CmeR structure is currently in progress.

  1. KELVIN-HELMHOLTZ INSTABILITY OF THE CME RECONNECTION OUTFLOW LAYER IN THE LOW CORONA

    SciTech Connect

    Foullon, Claire; Verwichte, Erwin; Nykyri, Katariina; Aschwanden, Markus J.; Hannah, Iain G.

    2013-04-20

    New capabilities for studying the Sun allow us to image for the first time the magnetic Kelvin-Helmholtz (KH) instability developing at the surface of a fast coronal mass ejecta (CME) less than 150 Mm above the solar surface. We conduct a detailed observational investigation of this phenomenon, observed off the east solar limb on 2010 November 3, in the EUV with SDO/AIA. In conjunction with STEREO-B/EUVI, we derive the CME source surface position. We ascertain the timing and early evolution of the CME outflow leading to the instability onset. We perform image and spectral analysis, exploring the CME plasma structuring and its parabolic flow pattern. As we evaluate and validate the consistency of the observations with theoretical considerations and predictions, we take the view that the ejecta layer corresponds to a reconnection outflow layer surrounding the erupting flux rope, accounting for the timing, high temperature ({approx}11.6 MK), and high flow shear ({approx}680 km s{sup -1}) on the unstable CME northern flank and for the observed asymmetry between the CME flanks. From the irregular evolution of the CME flow pattern, we infer a shear gradient consistent with expected spatial flow variations across the KH-unstable flank. The KH phenomenon observed is tied to the first stage of a linked flare-CME event.

  2. Measuring Classroom Management Expertise (CME) of Teachers: A Video-Based Assessment Approach and Statistical Results

    ERIC Educational Resources Information Center

    König, Johannes

    2015-01-01

    The study aims at developing and exploring a novel video-based assessment that captures classroom management expertise (CME) of teachers and for which statistical results are provided. CME measurement is conceptualized by using four video clips that refer to typical classroom management situations in which teachers are heavily challenged…

  3. MULTI-SPACECRAFT OBSERVATIONS OF THE 2008 JANUARY 2 CME IN THE INNER HELIOSPHERE

    SciTech Connect

    Zhao, X. H.; Feng, X. S.; Xiang, C. Q.; Li, Z.; Liu, Y.; Zhang, Y.; Wu, S. T.

    2010-05-10

    We perform a detailed analysis of a coronal mass ejection (CME) on 2008 January 2. The combination of the Solar and Heliospheric Observatory and the twin STEREO spacecraft provides three-point observations of this CME. We track the CME in imaging observations and compare its morphology and kinematics viewed from different vantage points. The shape, angular width, distance, velocity, and acceleration of the CME front are different in the observations of these spacecraft. We also compare the efficiency of several methods, which convert the elongation angles of the CME front in images to radial distances. The results of our kinematic analysis demonstrate that this CME experiences a rapid acceleration at the early stage, which corresponds to the flash phase of the associated solar flare in time. Then, at a height of about 3.7 solar radius, the CME reaches a velocity of 790 km s{sup -1} and propagates outward without an obvious deceleration. Because of its propagation direction away from the observers, the CME is not detected in situ by either ACE or STEREO.

  4. Promoting Physician Preventive Practices: Needs Assessment for CME in Breast Cancer Detection.

    ERIC Educational Resources Information Center

    Lane, Dorothy S.; Burg, Mary Ann

    1989-01-01

    Needs assessment for a continuing medical education (CME) intervention directed at increasing breast cancer screening of women over 50 included a survey of target primary care physicians (n=323) to explore areas of interest for CME in breast care detection and to establish baseline screening practices. A survey of 1,440 women in the target age…

  5. Prediction of in vitro and in vivo oestrogen receptor activity using hierarchical clustering

    EPA Science Inventory

    In this study, hierarchical clustering classification models were developed to predict in vitro and in vivo oestrogen receptor (ER) activity. Classification models were developed for binding, agonist, and antagonist in vitro ER activity and for mouse in vivo uterotrophic ER bindi...

  6. Earthquake cluster activity beneath the Tanzawa Mountains region, Japan: Migration of hypocenters and low stress drop

    NASA Astrophysics Data System (ADS)

    Yamada, T.; Yukutake, Y.

    2013-12-01

    An earthquake cluster activity was observed beneath the Tanzawa Mountains region, Japan with a depth of 20 km in the end of January, 2012. Japan Meteorological Agency (JMA) determined hypocenters of 76 earthquakes with M > 2 in the area within 50 hours. Five of them had magnitudes greater than 4 and the largest one was 5.4. Four out of the five earthquakes had the reverse-type focal mechanisms with the P axis in the NW-SE direction. First we relocated hypocenters of the activity following the method of Yukutake et al. (2012). We estimated relative arrival times of P and S waves by calculating the coefficients of the cross correlation and relocated hypocenters with the double-difference relocation method (Waldhauser and Ellsworth, 2000). We found that the cluster activity showed a migration from the first earthquake of the activity. The parabolic migration speed was consistent with the migration speed of the deep tremor sources (Ide et al., 2010) for which the fluid activity would play an important role. We then analyzed stress drops of 17 earthquakes with M > 3.5 that occurred from January, 2000 to June, 2012 in the area of the cluster activity. We calculated empirical Green's functions from waveforms of earthquakes with magnitudes of 3.0 to 3.2 and estimated stress drops of the earthquakes assuming that the source spectra can be expressed as the omega-squared model. We found that earthquakes of the cluster activity had smaller stress drops by an order of magnitude than the values of earthquakes that occurred in the same area before the cluster activity. These results suggest that the fluid played an important role for the earthquake cluster activity. That is, the fluid increased the pore pressure, decreased the effective normal stress and triggered the cluster activity. The difference of the rupture speed and the change of the rigidity might also be candidates that account for our results. They, however, can hardly explain the results quantitatively. Fig

  7. An Extended Membrane System with Active Membranes to Solve Automatic Fuzzy Clustering Problems.

    PubMed

    Peng, Hong; Wang, Jun; Shi, Peng; Pérez-Jiménez, Mario J; Riscos-Núñez, Agustín

    2016-05-01

    This paper focuses on automatic fuzzy clustering problem and proposes a novel automatic fuzzy clustering method that employs an extended membrane system with active membranes that has been designed as its computing framework. The extended membrane system has a dynamic membrane structure; since membranes can evolve, it is particularly suitable for processing the automatic fuzzy clustering problem. A modification of a differential evolution (DE) mechanism was developed as evolution rules for objects according to membrane structure and object communication mechanisms. Under the control of both the object's evolution-communication mechanism and the membrane evolution mechanism, the extended membrane system can effectively determine the most appropriate number of clusters as well as the corresponding optimal cluster centers. The proposed method was evaluated over 13 benchmark problems and was compared with four state-of-the-art automatic clustering methods, two recently developed clustering methods and six classification techniques. The comparison results demonstrate the superiority of the proposed method in terms of effectiveness and robustness. PMID:26790484

  8. Interaction between CME and surrounding magnetic fields producing multiple flaring sites

    NASA Astrophysics Data System (ADS)

    van Driel-Gesztelyi, Lidia M.

    2015-08-01

    L. van Driel-Gesztelyi (1,2,3), D. Baker (1), T. Török (4), E. Pariat (2), L.M. Green (1),D.R. Williams (1), J. Carlyle (1,5) G. Valori (1, 2), P. Démoulin (2), B. Kliem (1,7,8),D. Long (1), S.A. Matthews (1), J.-M. Malherbe (2)(1) UCL/MSSL, UK, (2) Paris Observatory, LESIA, CNRS, France, (3) Konkoly Observatory, Hungary, (4) Predictive Science, Dan Diego, USA, (5) Max Planck Inst., Göttingen, Germany, (6) INAF, Obs. Roma, Italy, (7) Potsdam Univ., Germany, (8) Yunnan Observatories, Kunming, ChinaAnalyzing Solar Dynamics Observatory (SDO) observations of the spectacular Coronal Mass Ejection eruption on 7 June 2011, we present evidence of coronal magnetic reconnection between the expanding magnetic structure of the CME and the magnetic fields of an adjacent active region (AR). The onset of reconnection first became apparent in the SDO/AIA images when filament plasma, originally contained within the erupting flux rope, was re-directed towards remote areas in the neighboring AR, tracing the change of large-scale magnetic connectivity. The observations are presented jointly with a topological analysis of the pre-eruption magnetic configuration, and a data-constrained numerical simulation of the three-AR complex, demonstrating the formation/intensification of current sheets along a pre-existing hyperbolic flux tube (HFT) at the interface between the CME and the neighboring AR, where a secondary flare ribbon was created. Reconnection across this current sheet resulted in the formation of new magnetic connections between the erupting magnetic structure and a neighboring AR about 200 Mm from the eruption site, in strong qualitative agreement with the observations. In addition, the CME temporarily created unusually dense plasma conditions around a reconnection region at high coronal altitudes, enabling us to observe emission resulting from it. We argue that this exceptional observation of a coronal brightening was directly observable at SDO/AIA wavelengths owing to the

  9. Clustering-Based Ensemble Learning for Activity Recognition in Smart Homes

    PubMed Central

    Jurek, Anna; Nugent, Chris; Bi, Yaxin; Wu, Shengli

    2014-01-01

    Application of sensor-based technology within activity monitoring systems is becoming a popular technique within the smart environment paradigm. Nevertheless, the use of such an approach generates complex constructs of data, which subsequently requires the use of intricate activity recognition techniques to automatically infer the underlying activity. This paper explores a cluster-based ensemble method as a new solution for the purposes of activity recognition within smart environments. With this approach activities are modelled as collections of clusters built on different subsets of features. A classification process is performed by assigning a new instance to its closest cluster from each collection. Two different sensor data representations have been investigated, namely numeric and binary. Following the evaluation of the proposed methodology it has been demonstrated that the cluster-based ensemble method can be successfully applied as a viable option for activity recognition. Results following exposure to data collected from a range of activities indicated that the ensemble method had the ability to perform with accuracies of 94.2% and 97.5% for numeric and binary data, respectively. These results outperformed a range of single classifiers considered as benchmarks. PMID:25014095

  10. Clustering-based ensemble learning for activity recognition in smart homes.

    PubMed

    Jurek, Anna; Nugent, Chris; Bi, Yaxin; Wu, Shengli

    2014-01-01

    Application of sensor-based technology within activity monitoring systems is becoming a popular technique within the smart environment paradigm. Nevertheless, the use of such an approach generates complex constructs of data, which subsequently requires the use of intricate activity recognition techniques to automatically infer the underlying activity. This paper explores a cluster-based ensemble method as a new solution for the purposes of activity recognition within smart environments. With this approach activities are modelled as collections of clusters built on different subsets of features. A classification process is performed by assigning a new instance to its closest cluster from each collection. Two different sensor data representations have been investigated, namely numeric and binary. Following the evaluation of the proposed methodology it has been demonstrated that the cluster-based ensemble method can be successfully applied as a viable option for activity recognition. Results following exposure to data collected from a range of activities indicated that the ensemble method had the ability to perform with accuracies of 94.2% and 97.5% for numeric and binary data, respectively. These results outperformed a range of single classifiers considered as benchmarks. PMID:25014095

  11. Influence of support hydroxides on the catalytic activity of oxidized gold clusters

    SciTech Connect

    Veith, Gabriel M; Lupini, Andrew R; Pennycook, Stephen J; Dudney, Nancy J

    2010-01-01

    Gold oxide nanoparticles were prepared on the native surface and a hydroxylated surface of a non-porous TiO2 support (Degussa P25). Scanning transmission electron microscopy results show the formation of similarly sized clusters on both support materials (1.86 and 1.61 nm clusters on the native oxide and the hydroxylated oxide respectively). X-ray absorption near edge spectroscopy and X-ray photoelectron spectroscopy clearly indicate the formation of Au3+ rich oxide nanoparticles. Despite the similar cluster sizes and oxidation states the gold oxide clusters grown on the hydroxylated surface were at least 180 times more catalytically active for the oxidation of carbon monoxide then those grown on the native oxide surface. These hydroxides are conveniently introduced during the solution phase synthesis of gold catalysts and play a dominate, but previously unrecognized, role in the catalytic properties of both oxidized and metallic gold particles.

  12. Human Frataxin Activates Fe–S Cluster Biosynthesis by Facilitating Sulfur Transfer Chemistry

    PubMed Central

    2015-01-01

    Iron–sulfur clusters are ubiquitous protein cofactors with critical cellular functions. The mitochondrial Fe–S assembly complex, which consists of the cysteine desulfurase NFS1 and its accessory protein (ISD11), the Fe–S assembly protein (ISCU2), and frataxin (FXN), converts substrates l-cysteine, ferrous iron, and electrons into Fe–S clusters. The physiological function of FXN has received a tremendous amount of attention since the discovery that its loss is directly linked to the neurodegenerative disease Friedreich’s ataxia. Previous in vitro results revealed a role for human FXN in activating the cysteine desulfurase and Fe–S cluster biosynthesis activities of the Fe–S assembly complex. Here we present radiolabeling experiments that indicate FXN accelerates the accumulation of sulfur on ISCU2 and that the resulting persulfide species is viable in the subsequent synthesis of Fe–S clusters. Additional mutagenesis, enzyme kinetic, UV–visible, and circular dichroism spectroscopic studies suggest conserved ISCU2 residue C104 is critical for FXN activation, whereas C35, C61, and C104 are all essential for Fe–S cluster formation on the assembly complex. These results cannot be fully explained by the hypothesis that FXN functions as an iron donor for Fe–S cluster biosynthesis, and further support an allosteric regulator role for FXN. Together, these results lead to an activation model in which FXN accelerates persulfide formation on NFS1 and favors a helix-to-coil interconversion on ISCU2 that facilitates the transfer of sulfur from NFS1 to ISCU2 as an initial step in Fe–S cluster biosynthesis. PMID:24971490

  13. Automatic CME front edge detection from STEREO white-light coronagraph images

    NASA Astrophysics Data System (ADS)

    Kirnosov, Vladimir; Chang, Lin-Ching; Pulkkinen, Antti

    2015-08-01

    The coronagraph images captured by a Solar Terrestrial Relations Observatory (STEREO) Ahead/Behind (A/B) spacecraft allow tracking of a coronal mass ejection (CME) from two different viewpoints and reconstructing its propagation in three-dimensional space. The reconstruction can be done using a triangulation technique that requires a CME front edge location. There are currently no robust automatic CME front edge detection methods that can be integrated with the triangulation technique. In this paper, we propose a novel automatic method to detect the front edge of the CME using STEREO coronagraph 2 red-colored Red, Green, Blue color model images. Our method consists of two modules: preprocessing and classification. The preprocessing module decomposes each coronagraph image into its three channels and uses only the red channel image for CME segmentation. The output of the preprocessing module is a set of segmented running-difference binary images which is fed into the classification module. These images are then transformed into polar coordinates followed by CME front edge detection based on the distance that CME travels in the field of view. The proposed method was validated against a manual method using total 56 CME events, 28 from STEREO A and 28 from STEREO B, captured in the period from 1 January 2008 to 16 August 2009. The results show that the proposed method is effective for CME front edge detection. The proposed method is useful in quantitative CME processing and analysis and will be immediately applicable to assist automatic triangulation method for real-time space weather forecasting.

  14. A Redox Active [2Fe-2S] Cluster on the Hydrogenase Maturase HydF.

    PubMed

    Shepard, Eric M; Byer, Amanda S; Betz, Jeremiah N; Peters, John W; Broderick, Joan B

    2016-06-28

    [FeFe]-hydrogenases are nature's most prolific hydrogen catalysts, excelling at facilely interconverting H2 and protons. The catalytic core common to all [FeFe]-hydrogenases is a complex metallocofactor, referred to as the H-cluster, which is composed of a standard [4Fe-4S] cluster linked through a bridging thiolate to a 2Fe subcluster harboring dithiomethylamine, carbon monoxide, and cyanide ligands. This 2Fe subcluster is synthesized and inserted into [FeFe]-hydrogenase by three maturase enzymes denoted HydE, HydF, and HydG. HydE and HydG are radical S-adenosylmethionine enzymes and synthesize the nonprotein ligands of the H-cluster. HydF is a GTPase that functions as a scaffold or carrier for 2Fe subcluster production. Herein, we utilize UV-visible, circular dichroism, and electron paramagnetic resonance spectroscopic studies to establish the existence of redox active [4Fe-4S] and [2Fe-2S] clusters bound to HydF. We have used spectroelectrochemical titrations to assign iron-sulfur cluster midpoint potentials, have shown that HydF purifies with a reduced [2Fe-2S] cluster in the absence of exogenous reducing agents, and have tracked iron-sulfur cluster spectroscopic changes with quaternary structural perturbations. Our results provide an important foundation for understanding the maturation process by defining the iron-sulfur cluster content of HydF prior to its interaction with HydE and HydG. We speculate that the [2Fe-2S] cluster of HydF either acts as a placeholder for HydG-derived Fe(CO)2CN species or serves as a scaffold for 2Fe subcluster assembly. PMID:27232385

  15. Clustering of diet- and activity-related parenting practices: cross-sectional findings of the INPACT study

    PubMed Central

    2013-01-01

    Background Various diet- and activity-related parenting practices are positive determinants of child dietary and activity behaviour, including home availability, parental modelling and parental policies. There is evidence that parenting practices cluster within the dietary domain and within the activity domain. This study explores whether diet- and activity-related parenting practices cluster across the dietary and activity domain. Also examined is whether the clusters are related to child and parental background characteristics. Finally, to indicate the relevance of the clusters in influencing child dietary and activity behaviour, we examined whether clusters of parenting practices are related to these behaviours. Methods Data were used from 1480 parent–child dyads participating in the Dutch IVO Nutrition and Physical Activity Child cohorT (INPACT). Parents of children aged 8–11 years completed questionnaires at home assessing their diet- and activity-related parenting practices, child and parental background characteristics, and child dietary and activity behaviours. Principal component analysis (PCA) was used to identify clusters of parenting practices. Backward regression analysis was used to examine the relationship between child and parental background characteristics with cluster scores, and partial correlations to examine associations between cluster scores and child dietary and activity behaviours. Results PCA revealed five clusters of parenting practices: 1) high visibility and accessibility of screens and unhealthy food, 2) diet- and activity-related rules, 3) low availability of unhealthy food, 4) diet- and activity-related positive modelling, and 5) positive modelling on sports and fruit. Low parental education was associated with unhealthy cluster 1, while high(er) education was associated with healthy clusters 2, 3 and 5. Separate clusters were related to both child dietary and activity behaviour in the hypothesized directions: healthy clusters

  16. Activity in galactic nuclei of cluster and field galaxies in the local universe

    NASA Astrophysics Data System (ADS)

    Hwang, H. S.; Park, C.; Elbaz, D.; Choi, Y.-Y.

    2012-02-01

    Aims: We study the environmental effects on the activity in galactic nuclei by comparing galaxies in clusters and in the field. Methods: Using a spectroscopic sample of galaxies in Abell clusters from the Sloan Digital Sky Survey Data Release 7, we investigate the dependence of nuclear activity on the physical parameters of clusters as well as the nearest neighbor galaxy. We also compare galaxy properties between active galactic nuclei (AGNs) hosts and non-AGN galaxies. Results: We find that the AGN fraction of early-type galaxies starts to decrease around one virial radius of clusters (r200,cl) as decreasing clustercentric radius, while that of late types starts to decrease close to the cluster center (R ~ 0.1-0.5r200,cl). The AGN fractions of early-type cluster galaxies, on average, are found to be lower than those of early-type field galaxies by a factor ~3. However, the mean AGN fractions of late-type cluster galaxies are similar to those of late-type field galaxies. The AGN fraction of early-type brightest cluster galaxies lies between those of other early-type, cluster and field galaxies with similar luminosities. In the field, the AGN fraction is strongly dependent on the morphology of and the distance to the nearest neighbor galaxy. We find an anti-correlation between the AGN fraction and the velocity dispersion of clusters for all subsamples divided by morphology and luminosity of host galaxies. The AGN power indicated by L [OIII] /MBH is found to depend strongly on the mass of host galaxies rather than the clustercentric radius. The difference in physical parameters such as luminosity, (u - r) colors, star formation rates, and (g - i) color gradients between AGN hosts and non-AGN galaxies is seen for both early and late types at all clustercentric radii, while the difference in structure parameters between the two is significant only for late types. Conclusions: These results support the idea that the activity in galactic nuclei is triggered through

  17. A search for flares and mass ejections on young late-type stars in the open cluster Blanco-1

    NASA Astrophysics Data System (ADS)

    Leitzinger, M.; Odert, P.; Greimel, R.; Korhonen, H.; Guenther, E. W.; Hanslmeier, A.; Lammer, H.; Khodachenko, M. L.

    2014-09-01

    We present a search for stellar activity (flares and mass ejections) in a sample of 28 stars in the young open cluster Blanco-1. We use optical spectra obtained with European Southern Observatory's Visible Multi-Object Spectrograph installed on the Very Large Telescope. From the total observing time of ˜5 h, we find four Hα flares but no distinct indication of coronal mass ejections (CMEs) on the investigated dK-dM stars. Two flares show `dips' in their light curves right before their impulsive phases which are similar to previous discoveries in photometric light curves of active dMe stars. We estimate an upper limit of <4 CMEs per day per star and discuss this result with respect to a empirical estimation of the CME rate of main-sequence stars. We find that we should have detected at least one CME per star with a mass of ≤ 3 × 1017 g depending on the star's X-ray luminosity, but the estimated Hα fluxes associated with these masses are below the detection limit of our observations. We conclude that the parameter which mainly influences the detection of stellar CMEs using the method of Doppler-shifted emission caused by moving plasma is not the spectral resolution/velocity but the flux/mass of the CME.

  18. E-learning for occupational physicians' CME: a study case.

    PubMed

    Mazzoleni, M Cristina; Rognoni, Carla; Finozzi, Enrico; Gri, Tommaso; Pagani, Marco; Imbriani, Marcello

    2011-01-01

    The present study reports the results of the evaluation of an e-learning CME course in the field of Occupational Medicine. In particular the following aspects have been investigated: If and how the course contents have met the educational users' needs; The effectiveness of the course in terms of knowledge improvement; Users' behaviour. Attendance data and results of a sample of 1128 attendees have been analyzed via ad hoc developed tools for direct inspection of Moodle CMS database. The results document the effectiveness of the e-learning course, as regards meeting the educational needs of physicians and also the improvement in terms of knowledge and problem solving skill acquisition. Users' behaviour has revealed a certain tendency for passing the tests, more than for pursuing the best possible result. Interaction with the tutor is low. PMID:21685595

  19. CME propagation: where does solar wind drag 'take over'?

    NASA Astrophysics Data System (ADS)

    Subramanian, P.

    2013-12-01

    Coronal mass ejections (CMEs) from the Sun are known to be acted upon by driving as well as drag forces. They are generally thought to be driven by Lorentz self-forces, while the drag is due to viscous interaction with the ambient solar wind. However, the typical heliocentric distances at which driving forces cease to be dominant (and solar wind drag becomes important) is not obvious for most CMEs. We use a recently developed microphysical model for solar wind viscous drag (Subramanian, Lara and Borgazzi 2012) together with data for driving forces from a well observed set of flux rope CMEs to answer this question. These results are important for building quantitative models for CME propagation, especially for those CMEs which are not fast enough for one to assume that they are acted upon primarily by drag forces.

  20. Combined Particle Acceleration in Solar Flares and Associated CME Shocks

    NASA Astrophysics Data System (ADS)

    Petrosian, Vahe

    2016-07-01

    I will review some observations of the characteristics of accelerated electrons seen near Earth (as SEPs) and those producing flare radiation in the low corona and chromosphere. The similarities and differences between the numbers, spectral distribution, etc. of the two population can shed light on the mechanism and sites of the acceleration. I will show that in some events the origin of both population appears to be the flare site while in others, with harder SEP spectra, in addition to acceleration at the flare site, there appears to be a need for a second stage re-acceleration in the associated fast Coronal Mass Ejection (CME) environment. This scenario can also describe a similar dichotomy that exists between the so called impulsive, highly enriched (3He and heavy ions) and softer SEP ion events, and stronger more gradual SEP events with near normal ionic abundances and harder spectra. I will also describe under what conditions such hardening can be achieved.

  1. Nozzle Driven Shocks in Post-CME Plasma

    NASA Astrophysics Data System (ADS)

    Scott, Roger B.; Longcope, D. W.; McKenzie, D. E.

    2012-05-01

    Models of patchy reconnection allow for heating and acceleration of plasma along reconnected field lines but do not offer a mechanism for transport of energy and momentum across field lines. Here we present a simple 2D model in which a localized region of reconnected flux creates an apparent constriction in the surrounding layer of unreconnected field. The moving constriction acts as a de Laval nozzle and ultimately leads to shocks which can extend out to several times the diameter of the flux tube, altering the density and temperature of the plasma in that region. These findings have direct implications for observations in the solar corona, particularly in regard to such phenomena as wakes seen behind supra-arcade downflows and high temperatures in post-CME current sheets. This work was supported by a joint grant from the NSF and DOE.

  2. CME Interaction with Coronal Holes and Their Interplanetary Consequences

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Makela, P.; Xie, H.; Akiyama, S.; Yashiro, S.

    2008-01-01

    A significant number of interplanetary (IP) shocks (-17%) during cycle 23 were not followed by drivers. The number of such "driverless" shocks steadily increased with the solar cycle with 15%, 33%, and 52% occurring in the rise, maximum, and declining phase of the solar cycle. The solar sources of 15% of the driverless shocks were very close the central meridian of the Sun (within approx.15deg), which is quite unexpected. More interestingly, all the driverless shocks with their solar sources near the solar disk center occurred during the declining phase of solar cycle 23. When we investigated the coronal environment of the source regions of driverless shocks, we found that in each case there was at least one coronal hole nearby suggesting that the coronal holes might have deflected the associated coronal mass ejections (CMEs) away from the Sun-Earth line. The presence of abundant low-latitude coronal holes during the declining phase further explains why CMEs originating close to the disk center mimic the limb CMEs, which normally lead to driverless shocks due to purely geometrical reasons. We also examined the solar source regions of shocks with drivers. For these, the coronal holes were located such that they either had no influence on the CME trajectories. or they deflected the CMEs towards the Sun-Earth line. We also obtained the open magnetic field distribution on the Sun by performing a potential field source surface extrapolation to the corona. It was found that the CMEs generally move away from the open magnetic field regions. The CME-coronal hole interaction must be widespread in the declining phase, and may have a significant impact on the geoeffectiveness of CMEs.

  3. Optical activity of a single MnAs cluster: Birefringence or Kerr effect

    NASA Astrophysics Data System (ADS)

    Leuschner, M.; Klar, P. J.; Heimbrodt, W.; Rühle, W. W.; Hara, S.; Stolz, W.; Volz, K.; Kurz, T.; Loidl, A.; Krug von Nidda, H.-A.

    2006-06-01

    We have grown In 0.54Ga 0.46As:Mn/MnAs granular paramagnetic-ferromagnetic hybrid structures by metal-organic vapor-phase epitaxy. The MnAs clusters have a Curie temperature of about 320 K. We have studied the optical activity of individual ferromagnetic MnAs clusters embedded in the paramagnetic In 0.54Ga 0.46As:Mn matrix at room temperature by far-field depolarization measurements. A scanning near-field optical microscopy set-up in constant height mode ( ≈100 nm above the sample surface) was used to achieve a high spatial resolution. Individual MnAs clusters rotate the linear polarization of the incoming light by almost 2∘ in this reflection geometry. This optical activity was analyzed in terms of birefringence and polar Kerr effect and correlated with the structural and magnetic properties of the MnAs clusters as determined by ferromagnetic resonance measurements. The optical activity of the MnAs clusters turns out to be dominated by linear birefringence caused by the uniaxial symmetry of the hexagonal crystal structure of MnAs. The polar Kerr effect plays a minor role in this experiment.

  4. The role of basic amino acid surface clusters on the collagenase activity of cathepsin K

    PubMed Central

    Nallaseth, Ferez S.; Lecaille, Fabien; Li, Zhenqiang; Brömme, Dieter

    2013-01-01

    Cathepsin K is a highly potent collagenase in osteoclasts and responsible for bone degradation. We have previously demonstrated that its unique collagenolytic activity is modulated by glycosaminoglycans that form high molecular complexes with the protease. However, mutational analysis of a specific glycosaminoglycan-cathepsin K binding site only led to a 60% reduction of the collagenolytic activity suggesting additional glycosaminoglycan binding sites or other determinants controlling this activity. We identified 8 cathepsin K specific arginine/lysine residues that form three positively charged clusters at the bottom part of the protease opposing the active site. These residues are highly conserved among mammalian, avian, and reptilian cathepsin K orthologues and to a lesser degree in amphibian and fish specimens. Mutational analysis of these residues revealed an approximately 50% reduction of the collagenolytic activity when the basic amino acids in cluster 2 (K106, K108, R108, R111) were mutated into alanine residues and resulted in a 100% loss of this activity when the mutations were expanded into cluster 3 (K122, R127). Cluster 1 mutations (K77, R79) had no effect. A partial rescue effect was observed when the hexa-mutant variant was combined with three mutations in the previously identified glycosaminoglycan binding site (N190, K101, L195K) indicating the relevance of at least two independent interaction sites. Amino acid substitutions in all sites had no effect on the catalytic efficacy of the protease variants as reflected in their unaltered peptidolytic and gelatinolytic activities and their overall protein stabilities. This study suggests that the basic amino acid clusters in cathepsin K are either involved in alternative glycoasaminoglycan binding sites, play other roles in the formation of collagenolytically active protease complexes or contribute in a yet unknown manner to the specific binding to collagen. PMID:24088021

  5. Preparation of Aun quantum clusters with catalytic activity in β-cyclodextrin polyurethane nanosponges.

    PubMed

    Vasconcelos, Diego Andrade; Kubota, Tatiana; Santos, Douglas C; Araujo, Marcia V G; Teixeira, Zaine; Gimenez, Iara F

    2016-01-20

    Here we report the use of β-cyclodextrin polyurethane nanosponges cross-linked with 1,6-hexamethylene diisocyanate as a template for the preparation of Aun quantum clusters, by the core-etching of glutathione-capped Au nanoparticles. The study of temporal evolution of the core-etching process using different Au concentrations indicated that formation of Aun clusters embedded in the nanosponge is favored by the use of lower Au concentrations, since it began at shorter times and lead to higher cluster loading. An estimation of the number of Au atoms based on the maximum photoluminescence wavelength suggested that, depending on the Au concentration and the core etching time, clusters with 11-15 atoms were formed. After excluding the possibility of an inclusion complex formation, evaluation of the catalytic activity of nanosponge-loaded Aun clusters toward the reduction of 4-nitrophenol has shown that the reaction is catalyzed by the Aun clusters with no induction time, following the Langmuir-Hinshelwood kinetic model. PMID:26572328

  6. Activation and adsorption of CO{sub 2} on copper surfaces and clusters

    SciTech Connect

    Gautam, Seema; Dharmvir, Keya; Goel, Neetu

    2014-04-24

    The activation and adsorption of CO{sub 2} over Cu{sub n} clusters have been investigated by first principle calculations. Results of these calculations are compared with the previous studies of adsorption of CO{sub 2} on Cu (hkl) surfaces [Wang et al. Surface Science 570 (2004) 205–217]. We find that CO{sub 2} is preferentially adsorbed over the clusters in comparison with Cu (hkl) surfaces. The Cu13 cluster in particular dissociates the CO{sub 2} molecule adsorbed on the one of the caps of the icosahedron into CO and atomic oxygen. This activated configuration can act as a precursor to reactions leading to hydrocarbon fuels from CO{sub 2}.

  7. Modeling magnetohydrodynamics and non-equilibrium SoHO/UVCS line emission of CME shocks

    NASA Astrophysics Data System (ADS)

    Pagano, P.; Raymond, J. C.; Reale, F.

    The Coronal Mass Ejections are plasma clouds expelled from the Sun into the interplanetary medium. We study the propagation of shock waves in the solar corona generated during Coronal Mass Ejections by means of a numerical multi-dimensional MHD model. The model describes the MHD evolution of a compressible plasma in an ambient magnetic field including tensor thermal conduction, radiative losses as main physical effects. We use the MHD version of the FLASH parallel hydrodynamic code with adaptive mesh refinement, originally developed at the University of Chicago USA). The code is highly modular and made efficiently parallel with the Message Passing Interface library. We analyze the diagnostic signatures of shock fronts generated by supersonic CME fragments detectable with the UltraViolet Coronagraphic Spectrometer on board the SoHO mission. To this aim we perform 3D MHD simulations of the shock propagation for the time it takes to cross the UVCS slit positioned at a distance of a few solar radii from the solar surface. In the presence of highly effective thermal conduction the simulation takes 200000 time steps to cover 1000 s of evolution. Considering a 3-D domain of 256x256x512 grid cells this kind of simulations requires thousands of hours of computer time and therefore high performance computing (HPC) systems. The simulations were run on the CINECA IBM/SP5 HPC cluster within the INAF/CINECA agreement. We show simulation results and some implications for UVCS observations.

  8. a Three-Step Spatial-Temporal Clustering Method for Human Activity Pattern Analysis

    NASA Astrophysics Data System (ADS)

    Huang, W.; Li, S.; Xu, S.

    2016-06-01

    How people move in cities and what they do in various locations at different times form human activity patterns. Human activity pattern plays a key role in in urban planning, traffic forecasting, public health and safety, emergency response, friend recommendation, and so on. Therefore, scholars from different fields, such as social science, geography, transportation, physics and computer science, have made great efforts in modelling and analysing human activity patterns or human mobility patterns. One of the essential tasks in such studies is to find the locations or places where individuals stay to perform some kind of activities before further activity pattern analysis. In the era of Big Data, the emerging of social media along with wearable devices enables human activity data to be collected more easily and efficiently. Furthermore, the dimension of the accessible human activity data has been extended from two to three (space or space-time) to four dimensions (space, time and semantics). More specifically, not only a location and time that people stay and spend are collected, but also what people "say" for in a location at a time can be obtained. The characteristics of these datasets shed new light on the analysis of human mobility, where some of new methodologies should be accordingly developed to handle them. Traditional methods such as neural networks, statistics and clustering have been applied to study human activity patterns using geosocial media data. Among them, clustering methods have been widely used to analyse spatiotemporal patterns. However, to our best knowledge, few of clustering algorithms are specifically developed for handling the datasets that contain spatial, temporal and semantic aspects all together. In this work, we propose a three-step human activity clustering method based on space, time and semantics to fill this gap. One-year Twitter data, posted in Toronto, Canada, is used to test the clustering-based method. The results show that the

  9. LUMINOUS X-RAY ACTIVE GALACTIC NUCLEI IN CLUSTERS OF GALAXIES

    SciTech Connect

    Koulouridis, E.; Plionis, M.

    2010-05-10

    We present a study of X-ray active galactic nucleus (AGN) overdensities in 16 Abell clusters, within the redshift range 0.073 < z < 0.279, in order to investigate the effect of the hot inter-cluster environment on the triggering of the AGN phenomenon. The X-ray AGN overdensities, with respect to the field expectations, were estimated for sources with L{sub x} {>=} 10{sup 42} erg s{sup -1} (at the redshift of the clusters) and within an area of 1 h {sup -1} {sub 72} Mpc radius (excluding the core). To investigate the presence or absence of a true enhancement of luminous X-ray AGNs in the cluster area, we also derived the corresponding optical galaxy overdensities, using a suitable range of r-band magnitudes. We always find the latter to be significantly higher (and only in two cases roughly equal) with respect to the corresponding X-ray overdensities. Over the whole cluster sample, the mean X-ray point-source overdensity is a factor of {approx}4 less than that corresponding to bright optical galaxies, a difference which is significant at a >0.995 level, as indicated by an appropriate student's t-test. We conclude that the triggering of luminous X-ray AGNs in rich clusters is strongly suppressed. Furthermore, searching for optical Sloan Digital Sky Survey counterparts of all the X-ray sources, associated with our clusters, we found that about half appear to be background QSOs, while others are background and foreground AGNs or stars. The true overdensity of X-ray point sources, associated with the clusters, is therefore even smaller than what our statistical approach revealed.

  10. Radio Observations of the CME-poor region AR2192: a type II burst with no CME driver

    NASA Astrophysics Data System (ADS)

    Hudson, Hugh; Vilmer, Nicole; Wakeford, Peter

    2015-04-01

    The remarkable sunspot group NOAA AR 2192 (October 2014) produced X-class flares without CMEs, and in general was large and powerful but with little heliospheric interaction. We discuss radio perspectives on the development of this region. In particular there were decametric type II bursts observed in association with jet-like flares SOL2014-10-21T12:28 (C4.4) and SOL2014-10-21T13:38 (M1.2), as first noted in the Glasgow Callisto observatory and confirmed via the Meudon decametric array. In cases such as this, the global coronal wave responsible for the type II emission seems to originate from an ejection of material flowing along a previously established field structure, rather than perpendicular to it as in a CME.

  11. The Width of a CME and the Source of the Driving Magnetic Explosion

    NASA Technical Reports Server (NTRS)

    Moore, R. L.; Sterling, A. C.; Suess, S. T.

    2007-01-01

    We show that the strength of the magnetic field in the area covered by the flare arcade following a CME-producing ejective solar eruption can be estimated from the final angular width of the CME in the outer corona and the final angular width of the flare arcade. We assume (1) the flux-rope plasmoid ejected from the flare site becomes the interior of the CME plasmoid, (2) in the outer corona the CME is roughly a "spherical plasmoid with legs" shaped like a light bulb, and (3) beyond some height in or below the outer corona the CME plasmoid is in lateral pressure balance with the surrounding magnetic field. The strength of the nearly radial magnetic field in the outer corona is estimated from the radial component of the interplanetary magnetic field measured by Ulysses. We apply this model to three well-observed CMEs that exploded from flare regions of extremely different size and magnetic setting. In each event, the estimated source-region field strength is appropriate for the magnetic setting of the flare. This agreement indicates via the model that CMEs (1) are propelled by the magnetic field of the CME plasmoid pushing against the surrounding magnetic field, and (2) can explode from flare regions that are laterally far offset from the radial path of the CME in the outer corona.

  12. User Activity Recognition in Smart Homes Using Pattern Clustering Applied to Temporal ANN Algorithm.

    PubMed

    Bourobou, Serge Thomas Mickala; Yoo, Younghwan

    2015-01-01

    This paper discusses the possibility of recognizing and predicting user activities in the IoT (Internet of Things) based smart environment. The activity recognition is usually done through two steps: activity pattern clustering and activity type decision. Although many related works have been suggested, they had some limited performance because they focused only on one part between the two steps. This paper tries to find the best combination of a pattern clustering method and an activity decision algorithm among various existing works. For the first step, in order to classify so varied and complex user activities, we use a relevant and efficient unsupervised learning method called the K-pattern clustering algorithm. In the second step, the training of smart environment for recognizing and predicting user activities inside his/her personal space is done by utilizing the artificial neural network based on the Allen's temporal relations. The experimental results show that our combined method provides the higher recognition accuracy for various activities, as compared with other data mining classification algorithms. Furthermore, it is more appropriate for a dynamic environment like an IoT based smart home. PMID:26007738

  13. User Activity Recognition in Smart Homes Using Pattern Clustering Applied to Temporal ANN Algorithm

    PubMed Central

    Bourobou, Serge Thomas Mickala; Yoo, Younghwan

    2015-01-01

    This paper discusses the possibility of recognizing and predicting user activities in the IoT (Internet of Things) based smart environment. The activity recognition is usually done through two steps: activity pattern clustering and activity type decision. Although many related works have been suggested, they had some limited performance because they focused only on one part between the two steps. This paper tries to find the best combination of a pattern clustering method and an activity decision algorithm among various existing works. For the first step, in order to classify so varied and complex user activities, we use a relevant and efficient unsupervised learning method called the K-pattern clustering algorithm. In the second step, the training of smart environment for recognizing and predicting user activities inside his/her personal space is done by utilizing the artificial neural network based on the Allen’s temporal relations. The experimental results show that our combined method provides the higher recognition accuracy for various activities, as compared with other data mining classification algorithms. Furthermore, it is more appropriate for a dynamic environment like an IoT based smart home. PMID:26007738

  14. The solar minimum X2.6/1B flare and CME of 9 July 1996. Pt. 1; Solar data

    NASA Technical Reports Server (NTRS)

    Andrews, M. D.; Dryer, M.; Aurass, H.; DeForest, C.; Kiplinger, A. L.; Meisner, R.; Paswaters, S. E.; Smith, Z.; Tappin, S. J.; Thompson, B. J.; Watari, S.-I.; Lamy, P.; Mann, G.; Schwenn, R.; Michels, D. J.; Brueckner, G. E.; Howard, R. A.; Koomen, M.

    1997-01-01

    The solar observations from GOES-8, the Solar and Heliospheric Observatory (SOHO), and the Yohkoh satellite concerning the events of the X-class flare are discussed. The Michelson Doppler imager (MDI) magnetometer shows a new region of magnetic activity in AR 7978. The rapid development and evolution of this region is shown by the MDI and the extreme-ultraviolet Doppler telescope (EDT) data. The coronal mass ejections (CMEs) observed using coronagraphs are presented. The possible association between the CME and the X-flare is considered.

  15. Heliospheric tracking of enhanced density structures of the 6 October 2010 CME

    NASA Astrophysics Data System (ADS)

    Mishra, Wageesh; Srivastava, Nandita

    2015-07-01

    A Coronal Mass Ejection (CME) is an inhomogeneous structure consisting of different features which evolve differently with the propagation of the CME. Simultaneous heliospheric tracking of different observed features of a CME can improve our understanding about relative forces acting on them. It also helps to estimate accurately their arrival times at the Earth and identify them in in-situ data. This also enables finding any association between remotely observed features and in-situ observations near the Earth. In this paper, we attempt to continuously track two density enhanced features in the CME of 6 October 2010, one at the front and another at the rear edge. This is achieved by using time-elongation maps constructed from STEREO/SECCHI observations. We derive the kinematics of the tracked features using various reconstruction methods. The estimated kinematics are used as inputs in the Drag Based Model (DBM) to estimate the arrival time of the tracked features of the CME at L1. On comparing the estimated kinematics as well as the arrival times of the remotely observed features with in-situ observations by Advanced Composition Explorer (ACE) and Wind, we find that the tracked bright feature at the rear edge of 6 October 2010 CME corresponds most probably to the enhanced density structure after the magnetic cloud detected by ACE and Wind. In-situ plasma and compositional parameters provide evidence that the rear edge density structure may correspond to a filament associated with the CME while the density enhancement at the front corresponds to the leading edge of the CME. Based on this single event study, we discuss the relevance and significance of Heliospheric Imager (HI) observations in identification of the three-part structure of the CME.

  16. Effects of the 5 October 1996 CME at 4.4 AU: Ulysses observations

    SciTech Connect

    Marsden, R.G.; Desai, M.I.; Sanderson, T.R.; Forsyth, R.J.; Gosling, J.T.

    1997-09-01

    The authors present observations from Ulysses associated with a large coronal mass ejection (CME) that lifted off the west limb of the Sun on 5 October, 1996. The study focuses on the effects of the interplanetary counterpart of the CME on the energetic particle populations at the location of Ulysses, in particular the effect on the sequence of corotating enhancements that had been observed prior to its arrival. They conclude that, despite its large spatial extent, the CME caused no permanent deformation of the heliospheric current sheet.

  17. Transforming in-situ observations of CME-driven shock accelerated protons into the shock's reference frame.

    NASA Astrophysics Data System (ADS)

    Robinson, I. M.; Simnett, G. M.

    2005-07-01

    We examine the solar energetic particle event following solar activity from 14, 15 April 2001 which includes a "bump-on-the-tail" in the proton energy spectra at 0.99 AU from the Sun. We find this population was generated by a CME-driven shock which arrived at 0.99 AU around midnight 18 April. As such this population represents an excellent opportunity to study in isolation, the effects of proton acceleration by the shock. The peak energy of the bump-on-the-tail evolves to progressively lower energies as the shock approaches the observing spacecraft at the inner Lagrange point. Focusing on the evolution of this peak energy we demonstrate a technique which transforms these in-situ spectral observations into a frame of reference co-moving with the shock whilst making allowance for the effects of pitch angle scattering and focusing. The results of this transform suggest the bump-on-the-tail population was not driven by the 15 April activity but was generated or at least modulated by a CME-driven shock which left the Sun on 14 April. The existence of a bump-on-the-tail population is predicted by models in Rice et al. (2003) and Li et al. (2003) which we compare with observations and the results of our analysis in the context of both the 14 April and 15 April CMEs. We find an origin of the bump-on-the-tail at the 14 April CME-driven shock provides better agreement with these modelled predictions although some discrepancy exists as to the shock's ability to accelerate 100 MeV protons. Keywords. Solar physics, astrophysics and astronomy (Energetic particles; Flares and mass ejections) Space plasma physics (Transport processes)

  18. Hemoglobin–Albumin Cluster Incorporating a Pt Nanoparticle: Artificial O2 Carrier with Antioxidant Activities

    PubMed Central

    Hosaka, Hitomi; Haruki, Risa; Yamada, Kana; Böttcher, Christoph; Komatsu, Teruyuki

    2014-01-01

    A covalent core–shell structured protein cluster composed of hemoglobin (Hb) at the center and human serum albumins (HSA) at the periphery, Hb-HSAm, is an artificial O2 carrier that can function as a red blood cell substitute. Here we described the preparation of a novel Hb-HSA3 cluster with antioxidant activities and its O2 complex stable in aqueous H2O2 solution. We used an approach of incorporating a Pt nanoparticle (PtNP) into the exterior HSA unit of the cluster. A citrate reduced PtNP (1.8 nm diameter) was bound tightly within the cleft of free HSA with a binding constant (K) of 1.1×107 M−1, generating a stable HSA-PtNP complex. This platinated protein showed high catalytic activities for dismutations of superoxide radical anions (O2•–) and hydrogen peroxide (H2O2), i.e., superoxide dismutase and catalase activities. Also, Hb-HSA3 captured PtNP into the external albumin unit (K = 1.1×107 M−1), yielding an Hb-HSA3(PtNP) cluster. The association of PtNP caused no alteration of the protein surface net charge and O2 binding affinity. The peripheral HSA-PtNP shell prevents oxidation of the core Hb, which enables the formation of an extremely stable O2 complex, even in H2O2 solution. PMID:25310133

  19. RADIO-LOUD ACTIVE GALACTIC NUCLEUS: IS THERE A LINK BETWEEN LUMINOSITY AND CLUSTER ENVIRONMENT?

    SciTech Connect

    Ineson, J.; Croston, J. H.; Hardcastle, M. J.; Jarvis, M.; Kraft, R. P.; Evans, D. A.

    2013-06-20

    We present here the first results from the Chandra ERA (Environments of Radio-loud AGN) Large Project, characterizing the cluster environments of a sample of 26 radio-loud active galactic nuclei (AGNs) at z {approx} 0.5 that covers three decades of radio luminosity. This is the first systematic X-ray environmental study at a single epoch, and has allowed us to examine the relationship between radio luminosity and cluster environment without the problems of Malmquist bias. We have found a weak correlation between radio luminosity and host cluster X-ray luminosity, as well as tentative evidence that this correlation is driven by the subpopulation of low-excitation radio galaxies, with high-excitation radio galaxies showing no significant correlation. The considerable scatter in the environments may be indicative of complex relationships not currently included in feedback models.

  20. Anaerobic central metabolic pathways active during polyhydroxyalkanoate production in uncultured cluster 1 Defluviicoccus enriched in activated sludge communities.

    PubMed

    Burow, Luke C; Mabbett, Amanda N; Borrás, Luis; Blackall, Linda L

    2009-09-01

    A glycogen nonpolyphosphate-accumulating organism (GAO) enrichment culture dominated by the Alphaproteobacteria cluster 1 Defluviicoccus was investigated to determine the metabolic pathways involved in the anaerobic formation of polyhydroxyalkanoates, carbon storage polymers important for the proliferation of microorganisms in enhanced biological phosphorus removal processes. FISH-microautoradiography and post-FISH fluorescent chemical staining confirmed acetate assimilation as polyhydroxyalkanoates in cluster 1 Defluviicoccus under anaerobic conditions. Chemical inhibition of glycolysis using iodoacetate, and of isocitrate lyase by 3-nitropropionate and itaconate, indicated that carbon is likely to be channelled through both glycolysis and the glyoxylate cycle in cluster 1 Defluviicoccus. The effect of metabolic inhibitors of aconitase (monofluoroacetate) and succinate dehydrogenase (malonate) suggested that aconitase, but not succinate dehydrogenase, was active, providing further support for the role of the glyoxylate cycle in these GAOs. Metabolic inhibition of fumarate reductase using oxantel decreased polyhydroxyalkanoate production. This indicated reduction of fumarate to succinate and the operation of the reductive branch of the tricarboxylic acid cycle, which is possibly important in the production of the polyhydroxyvalerate component of polyhydroxyalkanoates observed in cluster 1 Defluviicoccus enrichment cultures. These findings were integrated with previous metabolic models for GAOs and enabled an anaerobic central metabolic pathway model for polyhydroxyalkanoate formation in cluster 1 Defluviicoccus to be proposed. PMID:19622073

  1. The RACE-OC project: Rotation and Activity Evolution in Open Clusters

    NASA Astrophysics Data System (ADS)

    Messina, S.; Distefano, E.; Parihar, Padmakar; Busà, I.; Cutispoto, G.; Lanza, A. F.; Lanzafame, A.; Pagano, I.; Biazzo, K.; Leto, G.; Hatzidimitriou, D.; Kim, S.-L.; Koo, J.-R.; Kang, Y. B.

    2009-02-01

    The RACE-OC project, standing for Rotation and Activity Evolution in Open Clusters, is a long-term project aimed at studying the evolution of rotation and magnetic activity of late-type members of stellar open clusters. Magnetic fields play a fundamental role in altering the rotational properties of late-type stars. They are responsible, e.g., for angular momentum loss in the wind or its redistribution in the stellar interior. Magnetic fields in late-type stars and their related phenomena, such as photospheric cool spots and bright faculae, chromospheric plages, and X-ray emission, in turn depend on the stellar rotation which controls the efficiency of the hydromagnetic dynamo. Thus, the evolution of angular momentum and magnetic activity offer complementary approaches to understanding the mechanisms by which rotation and magnetic fields influence each other in late-type stars.

  2. Radio Tracking of a White-Light CME from Solar Corona to Interplanetary Medium

    NASA Technical Reports Server (NTRS)

    Reiner, M. J.; Kaiser, Michael L.; Plunkett, S. P.; Prestage, N. P.

    1999-01-01

    We analyze the radio emissions associated with a flare/CME event on the sun. For this solar event there were type II radio emissions observed in both the metric and decametric to kilometric wavelength regimes. By comparing the dynamics of the CME with that implied by the frequencies and frequency-drift rates of the type II radio emissions, it is concluded that only the decametric/kilometric type II radio emissions are associated with the CME. We provide the first direct one-to-one comparison between a CME and the associated type II radio emissions. The dynamics implied by the metric type II radio emissions suggest a distinct coronal shock, associated with the flare, which only produces radio emissions in the low corona.

  3. CME on Oct. 21, 2011 Caused Red Aurora in U.S.

    NASA Video Gallery

    The SOlar Heliospheric Observatory (SOHO) captured this "coronograph" – so-called because the images block the sun, and only show the sun's atmosphere, or corona. The coronal mass ejection (CME)...

  4. Dependence of CME Propagation on Parameters of the Ejecta and Ambient Solar Wind

    NASA Astrophysics Data System (ADS)

    Li, Y.; Lynch, B. J.; Luhmann, J. G.; Krauss-Varban, D.; Thernisien, A.; Vourlidas, A.; MacNeice, P. J.

    2009-12-01

    CME propagation through the heliosphere has been one of the most uncertain problems, due to its complex nature and sparse observations in the vast space. CME travel time, speed and trajectory have been often unpredictable, because they may be modified going through ambient solar wind streams and IMF structure. All of these parameters are important for understanding CMEs and their space weather consequences. Direct observations of CME propagation through to 1AU have only become a reality since the recent STEREO Heliospheric Imager (HI) observations. Based on a few strategically selected CMEs that vary in parameter space and situated in different solar wind/IMF conditions, we perform several CCMC ENLIL with cone model simulations to study the propagation. Comparisons between modeling results including CME driven shock properties, travel time, 3D trajectory, and distortion of the ejecta (limited to the model approximation) will be made. Comparisons are also made between modeling, HI imaging results, and observed in-situ parameters when available.

  5. Is the cluster environment quenching the Seyfert activity in elliptical and spiral galaxies?

    NASA Astrophysics Data System (ADS)

    de Souza, R. S.; Dantas, M. L. L.; Krone-Martins, A.; Cameron, E.; Coelho, P.; Hattab, M. W.; de Val-Borro, M.; Hilbe, J. M.; Elliott, J.; Hagen, A.; COIN Collaboration

    2016-09-01

    We developed a hierarchical Bayesian model (HBM) to investigate how the presence of Seyfert activity relates to their environment, herein represented by the galaxy cluster mass, M200, and the normalized cluster centric distance, r/r200. We achieved this by constructing an unbiased sample of galaxies from the Sloan Digital Sky Survey, with morphological classifications provided by the Galaxy Zoo Project. A propensity score matching approach is introduced to control the effects of confounding variables: stellar mass, galaxy colour, and star formation rate. The connection between Seyfert-activity and environmental properties in the de-biased sample is modelled within an HBM framework using the so-called logistic regression technique, suitable for the analysis of binary data (e.g. whether or not a galaxy hosts an AGN). Unlike standard ordinary least square fitting methods, our methodology naturally allows modelling the probability of Seyfert-AGN activity in galaxies on their natural scale, i.e. as a binary variable. Furthermore, we demonstrate how an HBM can incorporate information of each particular galaxy morphological type in an unified framework. In elliptical galaxies our analysis indicates a strong correlation of Seyfert-AGN activity with r/r200, and a weaker correlation with the mass of the host cluster. In spiral galaxies these trends do not appear, suggesting that the link between Seyfert activity and the properties of spiral galaxies are independent of the environment.

  6. Lymphokine-activated killer (LAK) cell phenomenon in cluster headache. "In vitro" activation by recombinant interleukin-2.

    PubMed

    Giacovazzo, M; Stirparo, G; DeStefano, L; Martelletti, P; Rinaldi-Garaci, C

    1989-03-01

    Previous studies showed that the Natural Killer (NK) activity of peripheral blood lymphocytes (PBL) from cluster headache (CH) patients is lower than that of controls. This decreased activity seems to be independent of the cluster period. beta-interferon has been shown to be more effective in increasing NK activity when incubated with PBL from CH patients, than with PBL from control donors. Lymphokine-Activated Killer (LAK) cells can be generated by incubation of human PBL in recombinant Interleukin-2 (rIL-2). This phenomenon was studied in 10 CH patients and 8 healthy volunteers. PBL were activated to LAK cells by "in vitro" incubation for 72 hours in Control Medium containing rIL-2 (1000 I.U./ml). A four hour Chromium 51 release was used to measure LAK Cell Killing of K562 target cells. The released radioactivity was measured in a gamma scintillation counter. The CH patients showed a marked increase of LAK generation compared to control subjects. This effect seems to be augmented during the cluster period. PMID:2785095

  7. Membership and Coronal Activity in the NGC 2232 and Cr 140 Open Clusters

    NASA Technical Reports Server (NTRS)

    Patten, Brian M.; Oliversen, Ronald J. (Technical Monitor)

    2001-01-01

    This is the second annual performance report for our grant "Membership and Coronal Activity in the NGC 2232 and Cr 140 Open Clusters." We propose to identify X-ray sources and extract net source counts in 8 archival ROSAT HRI images in the regions of the NGC 2232 and Cr 140 open clusters. These X-ray data will be combined with ground-based photometry and spectroscopy in order to identify G, K, and early-M type cluster members. At present, no members later than approximately F5 are currently known for either cluster. With ages of approximately 25 Myr and at a distance of just 320 - 360 pc, the combined late-type membership of the NGC 2232 and Cr 140 clusters will yield an almost unique sample of solar-type stars in the post-T Tauri/pre-main sequence phase of evolution. These stars will be used to assess the level and dispersion in coronal activity levels, as part of a probe of the importance of magnetic braking and the level of magnetic dynamo activity, for solar-type stars just before they reach the ZAMS. Over the past year we have successfully acquired all of the ground-based data necessary to support the analysis of the archival ROSAT X-ray data in the regions around both of these clusters. By the end of 2001 we expect to have completed the reduction and analysis of the ground-based photometry and spectroscopy and will begin the integration of these data with the ROSAT X-ray data. A certain amount of pressure to complete the work on NGC 2232 is coming from the SIRTF project, as this cluster may be a key component to a circumstellar disk evolution GTO program. We are only too happy to try to help and have worked to speed the analysis as much as possible. The primary activity to be undertaken in the next few months is the integration of the groundbased photometry and spectroscopy with the archival ROSAT X-ray data and then writing the paper summarizing our results. The most time consuming portion of this next phase is, of course, seeing the paper through

  8. The synthesis, X-ray and DFT structures of the free ansa-cyclopentadiene ligand C 5H 5CMe 2CMe 2C 5H 5

    NASA Astrophysics Data System (ADS)

    Tacke, Matthias; Dunne, John Patrick; Fox, Shona; Linti, Gerald; Teuber, Roland

    2001-08-01

    The title compound 2,3-dicyclopentadiene-2,3-dimethylbutane (C 5H 5CMe 2CMe 2C 5H 5) 1 shows the typical staggered conformation of a highly substituted ethane derivative with the two largest substituents (C 5H 5) adopting a trans position. The molecule shows C 2 symmetry about the central C-C bond. Due to the high substitution, the central bond of the ethane is elongated to 160.0 pm (X-ray structure analysis) while the DFT calculation finds a value of 159.2 pm.

  9. Kinematic Treatment of CME Evolution in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Riley, Pete; Crooker, N. U.

    2004-01-01

    We present a kinematic study of the evolution of coronal mass ejections (CMEs) in the solar wind. Specifically, we consider the effects of: (1) spherical expansion; and (2) uniform expansion due to pressure gradients between the Interplanetary CME (ICME) and the ambient solar wind. We compare these results with an MHD model, which allows us to isolate these effects from the combined kinematic and dynamical effects, which are included in MHD models. They also provide compelling evidence that the fundamental cross section of so-called "force-free" flux ropes (or magnetic clouds) is neither circular or elliptical, but rather a convex-outward, "pancake" shape. We apply a force-free fitting to the magnetic vectors from the MHD simulation to assess how the distortion of the flux rope affects the fitting. In spite of these limitations, force-free fittings, which are straightforward to apply, do provide an important description of a number of parameters, including the radial dimension, orientation and chirality of the ICME.

  10. CME Eruption Onset Observations from EIT and SXT

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.

    2004-01-01

    Why CMEs erupt is a major outstanding puzzle of solar physics. Signatures observable at the earliest stages of eruption onset may hold precious clues about the onset mechanism. We present observations in EUV from SOHO/EIT and in soft X-rays from Yohkoh/SXT of the re-eruption and eruption phases of CME expulsion, along with the eruption's magnetic setting found from SOHO/MDI magnetograms. Most of our events involve clearly-observable filament eruptions and multiple neutral lines, and we use the magnetic settings and motions of the filaments to help infer the geometry and behavior of the associated erupting magnetic fields. Pre-eruption and early-eruption signatures include a relatively slow filament rise prior to eruption, and intensity "dimmings" and brightenings, both in the immediate neighborhood of the "core" (location of greatest magnetic shear) of the erupting fields and at locations remote from the core. These signatures and their relative timings place observational constraints on eruption mechanisms; our recent work has focused on implications for the so-called "tether cutting" and "breakout" models, but the same observational constraints are applicable to any model.