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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. 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

  4. 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.

  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. 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. …

  4. 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…

  5. 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…

  6. 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)

  7. 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

  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

    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.

  10. 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.

  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. 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.

  16. 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

  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. 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…

  12. 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…

  13. 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…

  14. 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…

  15. 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

  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. 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.

  18. 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

  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. 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.

  4. 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.

  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. 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...

  14. 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

  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. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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

  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. 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.

  9. 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.

  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. 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.

  14. 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

  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 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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…

  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. 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…

  7. 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…

  8. 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

  9. 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.

  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. 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

  13. 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

  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. 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.

  19. 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

  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. 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.

  5. 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.

  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. 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

  19. 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.

  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. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  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. 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

  17. 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.

  18. 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…

  19. 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…

  20. 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…

  1. 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.

  2. 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…

  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. 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…

  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. 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.

  10. 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

  11. 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

  12. 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.

  13. 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

  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. 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.

  19. 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.

  20. 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

  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. 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.

  6. 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

  7. 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}.

  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. 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.

  10. 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.

  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. 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.

  13. 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.

  14. 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

  15. 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

  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. 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.

  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. 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.

  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. 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.

  7. 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.

  8. X-ray and EUV Observations of CME Eruption Onset

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.

    2004-01-01

    Why Coronal Mass Ejections (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 from SOHO/EIT and from TRACE in EUV, and from Yohkoh/SXT in soft X-rays of the pre-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.

  9. X-Ray and EUV Observations of CME Eruption Onset

    NASA Astrophysics Data System (ADS)

    Sterling, Alphonse C.

    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 summarize and discuss observations from SOHO/EIT in EUV and from Yohkoh/SXT in soft X-rays of the pre-eruption and eruption phases of three CME expulsions, along with the eruptions' magnetic setting inferred from SOHO/MDI magnetograms. 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.

  10. 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.

  11. Teleconferencing Cme Programs to Rural Physicians: The University of Calgary Teleconference Program

    PubMed Central

    McDowell, C.A.; Challis, E.B.; Lockyer, J.M.; White, L.; Adams, K.; Parboosingh, I.J.

    1987-01-01

    Continuing medical education (CME) provides practising family physicians with the cornerstone of maintenance and improvement of skills. In rural areas the problems of isolation and distance are a barrier to continuing medical education. Provision of CME programs by audio-teleconferencing is an attempt to overcome these problems. This article describes the teleconference program of The University of Calgary, how it has developed over the five years of its existence, and its impact on rural physicians. PMID:21263789

  12. CME, Physicians, and Pavlov: Can We Change What Happens When Industry Rings the Bell?

    PubMed Central

    Lichter, Paul R.

    2008-01-01

    Purpose To show how physicians’ conditioned response to “keeping up” has helped industry’s opportunistic funding of continuing medical education (CME) and to propose ways to counter the conditioned response to the benefit of patients and the public. Methods Review of the literature and commentary on it. Results The pharmaceutical and device industries (hereafter referred to as industry) have a long history of bribing physicians to prescribe and use their products. Increasing pressure from Congress and the public has been brought to bear on industry gifting. This pressure, coinciding with increasing financial problems for the providers of CME, provided industry with reason and opportunity to expand its role in the financing of CME. Industry’s incentive to make its CME funding appear to be an arm’s-length transaction has spawned medical education service supplier (MESS) companies. Industry makes “unrestricted grants” to the MESS, and the MESS puts on the CME program. Helped by these CME programs, industry is able to subtly “buy” physicians one at a time, so that under the cover of “education” they and their academic institutions and medical organizations lose sight of being CME pawns in industry’s sole objective: profit. Conclusions Despite a vast literature showing how physician integrity is easy prey to industry, the medical profession continues to allow industry to have a detrimental influence on the practice of medicine and on physician respectability. It will take resolute action to change the medical profession’s conditioned response to industry’s CME bell and its negative effect on patients and the public. PMID:19277219

  13. 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

  14. 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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    Making use of eight archival ROSAT HRI images in the regions of the NGC 2232 and Cr 140, this project's primary focus is to identify X-ray sources and to extract net source counts for these sources in these two open clusters. These X-ray data would be combined with ground-based photometry and spectroscopy in order to identify G, K, and early-M type cluster members. Such membership data are important because, at present, no members later than spectral type approx. F5 are currently known for either cluster. With ages estimated to be approx. 25 Myr and at distances of just approx. 350 pc, the combined late-type membership of the NGC 2232 and Cr 140 clusters would yield an almost unique sample of solar-type stars in the post-T Tauri/pre-main sequence phase of evolution. These stars could be used to assess the level and dispersion of coronal activity levels, as a 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 zero-age main sequence.

  16. Role of hydroxyl groups on the stability and catalytic activity of Au clusters on rutile surface

    SciTech Connect

    Kent, Paul R

    2011-01-01

    Hydroxyls are present as surface terminations of transition metal oxides under ambient conditions and may modify the properties of supported catalysts. We perform first-principles density functional theory calculations to investigate the role of hydroxyls on the catalytic activity of supported gold clusters on TiO{sub 2} (rutile). We find that they have a long-range effect increasing the adhesion of gold clusters on rutile. While hydroxyls make one gold atom more electronegative, a more complex charge-transfer scenario is observed on larger clusters which are important for catalytic applications. This enhances the molecular adsorption and coadsorption energies of CO and O{sub 2}, thereby increasing the catalytic activity of gold clusters for CO oxidation, consistent with reported experiments. Hydroxyls at the interface between gold and rutile surface are most important to this process, even when not directly bound to gold. As such, accurate models of catalytic processes on gold and other catalysts should include the effect of surface hydroxyls.

  17. Constraining AGN triggering mechanisms through the clustering analysis of active black holes

    NASA Astrophysics Data System (ADS)

    Gatti, M.; Shankar, F.; Bouillot, V.; Menci, N.; Lamastra, A.; Hirschmann, M.; Fiore, F.

    2016-02-01

    The triggering mechanisms for active galactic nuclei (AGN) are still debated. Some of the most popular ones include galaxy interactions (IT) and disc instabilities (DIs). Using an advanced semi-analytic model (SAM) of galaxy formation, coupled to accurate halo occupation distribution modelling, we investigate the imprint left by each separate triggering process on the clustering strength of AGN at small and large scales. Our main results are as follows: (i) DIs, irrespective of their exact implementation in the SAM, tend to fall short in triggering AGN activity in galaxies at the centre of haloes with Mh > 1013.5 h-1 M⊙. On the contrary, the IT scenario predicts abundance of active central galaxies that generally agrees well with observations at every halo mass. (ii) The relative number of satellite AGN in DIs at intermediate-to-low luminosities is always significantly higher than in IT models, especially in groups and clusters. The low AGN satellite fraction predicted for the IT scenario might suggest that different feeding modes could simultaneously contribute to the triggering of satellite AGN. (iii) Both scenarios are quite degenerate in matching large-scale clustering measurements, suggesting that the sole average bias might not be an effective observational constraint. (iv) Our analysis suggests the presence of both a mild luminosity and a more consistent redshift dependence in the AGN clustering, with AGN inhabiting progressively less massive dark matter haloes as the redshift increases. We also discuss the impact of different observational selection cuts in measuring AGN clustering, including possible discrepancies between optical and X-ray surveys.

  18. Using Light-at-Night (LAN) Satellite Data for Identifying Clusters of Economic Activities in Europe

    NASA Astrophysics Data System (ADS)

    Rybnikova, N. A.; Portnov, B. A.

    2015-04-01

    Enterprises organized in clusters are often efficient in stimulating urban development, productivity and profit outflows. Identifying clusters of economic activities (EAs) thus becomes an important step in devising regional development policies, aimed at facilitating regional economic development. However, a major problem with cluster identification stems from limited reporting of specific EAs by individual countries and administrative entities. Even Eurostat, which maintains most advances regional databases, provides data for less than 50% of all regional subdivisions of the 3rd tier of the Nomenclature of Territorial Units for Statistics (NUTS3). Such poor reporting impedes identification of EA clusters and economic forces behind them. In this study, we test a possibility that missing data on geographic concentrations of EAs can be reconstructed using Light-at-Night (LAN) satellite measurements, and that such reconstructed data can then be used for the identification of EA clusters. As we hypothesize, LAN, captured by satellite sensors, is characterized by different intensity, depending on its source - production facilities, services, etc., - and this information can be used for EA identification. The study was carried out in three stages. First, using nighttime satellite images, we determined what types of EAs can be identified, with a sufficient degree of accuracy, by LAN they emit. Second, we calculated multivariate statistical models, linking EAs concentrations with LAN intensities and several locational and development attributes of NUTS3 regions in Europe. Next, using the obtained statistical models, we restored missing data on EAs across NUTS3 regions in Europe and identified clusters of EAs, using spatial analysis tools.

  19. Activity-induced clustering in model dumbbell swimmers: the role of hydrodynamic interactions.

    PubMed

    Furukawa, Akira; Marenduzzo, Davide; Cates, Michael E

    2014-08-01

    Using a fluid-particle dynamics approach, we numerically study the effects of hydrodynamic interactions on the collective dynamics of active suspensions within a simple model for bacterial motility: each microorganism is modeled as a stroke-averaged dumbbell swimmer with prescribed dipolar force pairs. Using both simulations and qualitative arguments, we show that, when the separation between swimmers is comparable to their size, the swimmers' motions are strongly affected by activity-induced hydrodynamic forces. To further understand these effects, we investigate semidilute suspensions of swimmers in the presence of thermal fluctuations. A direct comparison between simulations with and without hydrodynamic interactions shows these to enhance the dynamic clustering at a relatively small volume fraction; with our chosen model the key ingredient for this clustering behavior is hydrodynamic trapping of one swimmer by another, induced by the active forces. Furthermore, the density dependence of the motility (of both the translational and rotational motions) exhibits distinctly different behaviors with and without hydrodynamic interactions; we argue that this is linked to the clustering tendency. Our study illustrates the fact that hydrodynamic interactions not only affect kinetic pathways in active suspensions, but also cause major changes in their steady state properties. PMID:25215734

  20. Regional and global variations in the temporal clustering of tectonic tremor activity

    NASA Astrophysics Data System (ADS)

    Idehara, Koki; Yabe, Suguru; Ide, Satoshi

    2014-12-01

    The temporal distribution of tremor activity exhibits a highly non-Poissonian behavior, and its maximum period of non-Poissonian clustering statistically describes the recurrence interval of major tremor bursts. Here, we examine variations in the temporal clustering properties of tremor activity by assessing their characteristic times, which are determined by the maximum period of the non-Poissonian distribution. By applying a two-point correlation integral to some of the world's major tremor zones, including Shikoku, Kii-Tokai, and Kyushu in Japan; Cascadia, Jalisco, and Guerrero in Mexico; southern Chile; Taiwan; and Manawatu in New Zealand, we reveal local spatial variations in the temporal clustering properties in each tremor zone and show global-scale variations in tremor activity. The spatial variation in local tremor activity is characterized by a gradual transition in the along-dip direction and shorter-wavelength heterogeneities in the along-strike direction, possibly associated with a spatial change in frictional conditions at the plate interface and rheological conditions in the surrounding materials. The characteristic time correlates positively with locally measured median tremor duration, implying an inherent correlation between the moment release rate and the recurrence interval of tremors.

  1. Using hierarchical clustering methods to classify motor activities of COPD patients from wearable sensor data

    PubMed Central

    Sherrill, Delsey M; Moy, Marilyn L; Reilly, John J; Bonato, Paolo

    2005-01-01

    Background Advances in miniature sensor technology have led to the development of wearable systems that allow one to monitor motor activities in the field. A variety of classifiers have been proposed in the past, but little has been done toward developing systematic approaches to assess the feasibility of discriminating the motor tasks of interest and to guide the choice of the classifier architecture. Methods A technique is introduced to address this problem according to a hierarchical framework and its use is demonstrated for the application of detecting motor activities in patients with chronic obstructive pulmonary disease (COPD) undergoing pulmonary rehabilitation. Accelerometers were used to collect data for 10 different classes of activity. Features were extracted to capture essential properties of the data set and reduce the dimensionality of the problem at hand. Cluster measures were utilized to find natural groupings in the data set and then construct a hierarchy of the relationships between clusters to guide the process of merging clusters that are too similar to distinguish reliably. It provides a means to assess whether the benefits of merging for performance of a classifier outweigh the loss of resolution incurred through merging. Results Analysis of the COPD data set demonstrated that motor tasks related to ambulation can be reliably discriminated from tasks performed in a seated position with the legs in motion or stationary using two features derived from one accelerometer. Classifying motor tasks within the category of activities related to ambulation requires more advanced techniques. While in certain cases all the tasks could be accurately classified, in others merging clusters associated with different motor tasks was necessary. When merging clusters, it was found that the proposed method could lead to more than 12% improvement in classifier accuracy while retaining resolution of 4 tasks. Conclusion Hierarchical clustering methods are relevant

  2. RELATIONSHIP BETWEEN PARENTS' MOTIVATION FOR PHYSICAL ACTIVITY AND THEIR BELIEFS, AND SUPPORT OF THEIR CHILDREN'S PHYSICAL ACTIVITY: A CLUSTER ANALYSIS.

    PubMed

    Naisseh, Matilda; Martinent, Guillaume; Ferrand, Claude; Hautier, Christophe

    2015-08-01

    Previous studies have neglected the multivariate nature of motivation. The purpose of the current study was to first identify motivational profiles of parents' own physical activity. Second, the study examined if such profiles differ in the way in which parents perceive their children's competence in physical activity and the importance and support given to their children's physical activity. 711 physically active parents (57% mothers; M age = 39.7 yr.; children 6-11 years old) completed the Situational Motivation Scale, the Parents' Perceptions of Physical Activity Importance and their Children's Ability Questionnaire, and the Parental Support for Physical Activity Scale. Cluster analyses indicated four motivational profiles: Highly self-determined, Moderately self-determined, Non-self-determined, and Externally motivated profiles. Parents' beliefs and support toward their children's physical activity significantly differed across these profiles. It is the first study using Self-Determination Theory that provides evidence for the interpersonal outcomes of motivation. PMID:26302295

  3. A multiwavelength photometric census of AGN and star formation activity in the brightest cluster galaxies of X-ray selected clusters

    NASA Astrophysics Data System (ADS)

    Green, T. S.; Edge, A. C.; Stott, J. P.; Ebeling, H.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Metcalfe, N.; Kaiser, N.; Wainscoat, R. J.; Waters, C.

    2016-09-01

    Despite their reputation as being `red and dead', the unique environment inhabited by brightest cluster galaxies (BCGs) can often lead to a self-regulated feedback cycle between radiatively cooling intracluster gas and star formation and active galactic nucleus (AGN) activity in the BCG. However the prevalence of `active' BCGs, and details of the feedback involved, are still uncertain. We have performed an optical, UV and mid-IR photometric analysis of the BCGs in 981 clusters at 0.03 < z < 0.5, selected from the ROSAT All Sky Survey. Using Pan-STARRS PS1 3π, GALEX and WISE survey data we look for BCGs with photometric colours which deviate from that of the bulk population of passive BCGs - indicative of AGN and/or star formation activity within the BCG. We find that whilst the majority of BCGs are consistent with being passive, at least 14 per cent of our BCGs show a significant colour offset from passivity in at least one colour index. And, where available, supplementary spectroscopy reveals the majority of these particular BCGs show strong optical emission lines. On comparing BCG `activity' with the X-ray luminosity of the host cluster, we find that BCGs showing a colour offset are preferentially found in the more X-ray luminous clusters, indicative of the connection between BCG `activity' and the intracluster medium.

  4. AGN Activity and IGM Heating in the Fossil Cluster RX J1416.4+2315

    NASA Astrophysics Data System (ADS)

    Miraghaei, H.; Khosroshahi, H. G.; Sengupta, C.; Raychaudhury, S.; Jetha, N. N.; Abbassi, S.

    2015-12-01

    We study active galactic nucleus (AGN) activity in the fossil galaxy cluster RX J1416.4+2315. Radio observations were carried out using the Giant Metrewave Radio Telescope at two frequencies, 1420 and 610 MHz. A weak radio lobe that extends from the central nucleus is detected in the 610 MHz map. Assuming the radio lobe originated from the central AGN, we show that the energy injection into the intergalactic medium is only sufficient to heat up the central 50 kpc within the cluster core, while the cooling radius is larger (∼130 kpc). In the hardness ratio map, three low energy cavities have been identified. No radio emission is detected for these regions. We evaluated the power required to inflate the cavities and showed that the total energy budget is sufficient to offset the radiative cooling. We showed that the initial conditions would change the results remarkably. Furthermore, the efficiency of the Bondi accretion in powering the AGN has been estimated.

  5. Supersaturation and activity-rotation relation in PMS stars: the young cluster h Persei

    NASA Astrophysics Data System (ADS)

    Argiroffi, C.; Caramazza, M.; Micela, G.; Sciortino, S.; Moraux, E.; Bouvier, J.; Flaccomio, E.

    2016-05-01

    Context. Several studies showed that the magnetic activity of late-type main-sequence (MS) stars is characterized by different regimes and that their activity levels are well described by the Rossby number, Ro, defined as the ratio between the rotational period Prot and the convective turnover time. Very young pre-main-sequence (PMS) stars show, similarly to MS stars, intense magnetic activity. However, they do not show clear activity-rotation trends, and it still debated which stellar parameters determine their magnetic activity levels. Aims: To bridge the gap between MS and PMS stars, we studied the activity-rotation relation in the young cluster h Persei, a ~13 Myr old cluster, that contains both fast and slow rotators. The cluster members have ended their accretion phase and have developed a radiative core. It therefore offers us the opportunity of studying the activity level of intermediate-age PMS stars with different rotational velocities, excluding any interactions with the circumstellar environment. Methods: We constrained the magnetic activity levels of h Per members by measuring their X-ray emission from a Chandra observation, while rotational periods were obtained previously in the framework of the MONITOR project. By cross-correlating these data, we collected a final catalog of 414 h Per members with known rotational period, effective temperature, and mass. In 169 of these, X-ray emission has also been detected. Results: We found that h Per members with 1.0 M⊙activity regimes: fast rotators clearly show supersaturation, while slower rotators have activity levels compatible to the non-saturated regime. At 13 Myr, h Per is therefore the youngest cluster showing activity-rotation regimes analogous to those of MS stars, indicating that at this age, magnetic field production is most likely regulated by the αΩ type dynamo. Moreover, we observed that supersaturation is better described by Prot than Ro, and that the

  6. Supersaturation and activity-rotation relation in PMS stars: the young cluster h Persei

    NASA Astrophysics Data System (ADS)

    Argiroffi, C.; Caramazza, M.; Micela, G.; Sciortino, S.; Moraux, E.; Bouvier, J.; Flaccomio, E.

    2016-04-01

    Context. Several studies showed that the magnetic activity of late-type main-sequence (MS) stars is characterized by different regimes and that their activity levels are well described by the Rossby number, Ro, defined as the ratio between the rotational period Prot and the convective turnover time. Very young pre-main-sequence (PMS) stars show, similarly to MS stars, intense magnetic activity. However, they do not show clear activity-rotation trends, and it still debated which stellar parameters determine their magnetic activity levels. Aims: To bridge the gap between MS and PMS stars, we studied the activity-rotation relation in the young cluster h Persei, a ~13 Myr old cluster, that contains both fast and slow rotators. The cluster members have ended their accretion phase and have developed a radiative core. It therefore offers us the opportunity of studying the activity level of intermediate-age PMS stars with different rotational velocities, excluding any interactions with the circumstellar environment. Methods: We constrained the magnetic activity levels of h Per members by measuring their X-ray emission from a Chandra observation, while rotational periods were obtained previously in the framework of the MONITOR project. By cross-correlating these data, we collected a final catalog of 414 h Per members with known rotational period, effective temperature, and mass. In 169 of these, X-ray emission has also been detected. Results: We found that h Per members with 1.0 M⊙activity regimes: fast rotators clearly show supersaturation, while slower rotators have activity levels compatible to the non-saturated regime. At 13 Myr, h Per is therefore the youngest cluster showing activity-rotation regimes analogous to those of MS stars, indicating that at this age, magnetic field production is most likely regulated by the αΩ type dynamo. Moreover, we observed that supersaturation is better described by Prot than Ro, and that the

  7. O(2)And N(2)O Activation By Bi-, Tri-, And Tetranuclear Cu Clusters in Biology

    SciTech Connect

    Solomon, E.I.; Sarangi, R.; Woertink, J.S.

    2009-06-04

    Copper-cluster sites in biology exhibit unique spectroscopic features reflecting exchange coupling between oxidized Cu's and e (-) delocalization in mixed valent sites. These novel electronic structures play critical roles in O 2 binding and activation for electrophilic aromatic attack and H-atom abstraction, the 4e (-)/4H (+) reduction of O 2 to H 2O, and in the 2e (-)/2H (+) reduction of N 2O. These electronic structure/reactivity correlations are summarized.

  8. O2 and N2O activation by Bi-, Tri-, and tetranuclear Cu clusters in biology.

    PubMed

    Solomon, Edward I; Sarangi, Ritimukta; Woertink, Julia S; Augustine, Anthony J; Yoon, Jungjoo; Ghosh, Somdatta

    2007-07-01

    Copper-cluster sites in biology exhibit unique spectroscopic features reflecting exchange coupling between oxidized Cu's and e (-) delocalization in mixed valent sites. These novel electronic structures play critical roles in O 2 binding and activation for electrophilic aromatic attack and H-atom abstraction, the 4e (-)/4H (+) reduction of O 2 to H 2O, and in the 2e (-)/2H (+) reduction of N 2O. These electronic structure/reactivity correlations are summarized below. PMID:17472331

  9. Determining Distance, Age, and Activity in a New Benchmark Cluster: Ruprecht 147

    NASA Astrophysics Data System (ADS)

    Wright, Jason T.

    2009-08-01

    This proposal seeks 0.7 night of time on Hectochelle to observe the F, G, and K dwarfs of Ruprecht 147, recently identified as the closest old stellar cluster. At only ~ 200 pc and at an age of ~ 1-2 Gyr, this will be an important benchmark in stellar astrophysics, providing the only sample of spectroscopically accessible old, late-type stars of determinable age. Hectochelle is the ideal instrument to study this cluster, with a FOV, fiber count, and telescope aperture well matched to the cluster's diameter (~ 1°), richness (~ 100 identified members), and distance modulus (6.5-7 mag., putting the G and K dwarfs at B=11-15). Hectochelle will measure the Ca II line strengths of members to establish, for the first time, the chromospheric activity levels of a statistically significant sample of single, G and K dwarfs of this modest age. Hectochelle will also vet background stars for suitability as astrometric reference stars for a forthcoming HST FGS proposal to robustly measure the cluster's distance.

  10. Role of lattice defects in catalytic activities of graphene clusters for fuel cells.

    PubMed

    Zhang, Lipeng; Xu, Quan; Niu, Jianbing; Xia, Zhenhai

    2015-07-14

    Defects are common but important in graphene, which could significantly tailor the electronic structures and physical and chemical properties. In this study, the density functional theory (DFT) method was applied to study the electronic structure and catalytic properties of graphene clusters containing various point and line defects. The electron transfer processes in oxygen reduction reaction (ORR) on perfect and defective graphene clusters in fuel cells was simulated, and the free energy and reaction energy barrier of the elementary reactions were calculated to determine the reaction pathways. It was found that the graphene cluster with the point defect having pentagon rings at the zigzag edge, or line defects (grain boundaries) consisting of pentagon-pentagon-octagon or pentagon-heptagon chains also at the edges, shows the electrocatalytic capability for ORR. Four-electron and two-electron transfer processes could occur simultaneously on graphene clusters with certain types of defects. The energy barriers of the reactions are comparable to that of platinum(111). The catalytic active sites were determined on the defective graphene. PMID:26033301

  11. A Multi-Wavelength Photometric Census of AGN and Star Formation Activity in the Brightest Cluster Galaxies of X-ray Selected Clusters

    NASA Astrophysics Data System (ADS)

    Green, T. S.; Edge, A. C.; Stott, J. P.; Ebeling, H.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Metcalfe, N.; Kaiser, N.; Wainscoat, R. J.; Waters, C.

    2016-06-01

    Despite their reputation as being "red and dead", the unique environment inhabited by Brightest Cluster Galaxies (BCGs) can often lead to a self-regulated feedback cycle between radiatively cooling intracluster gas and star formation and AGN activity in the BCG. However the prevalence of "active" BCGs, and details of the feedback involved, are still uncertain. We have performed an optical, UV and Mid-IR photometric analysis of the BCGs in 981 clusters at 0.03 < z < 0.5, selected from the ROSAT All Sky Survey. Using Pan-STARRS PS1 3π, GALEX and WISE survey data we look for BCGs with photometric colours which deviate from that of the bulk population of passive BCGs - indicative of AGN and/or star formation activity within the BCG. We find that whilst the majority of BCGs are consistent with being passive, at least 14% of our BCGs show a significant colour offset from passivity in at least one colour index. And, where available, supplementary spectroscopy reveals the majority of these particular BCGs show strong optical emission lines. On comparing BCG "activity" with the X-ray luminosity of the host cluster, we find that BCGs showing a colour offset are preferentially found in the more X-ray luminous clusters, indicative of the connection between BCG "activity" and the intracluster medium.

  12. Ring opening and carbonylation of 3,3-dimethylthietane ligands in ruthenium carbonyl cluster complexes

    SciTech Connect

    Adams, R.D.; Belinski, J.A.; Yamamoto, J.H.

    1992-10-01

    When heated to 97{degrees}C, the complex Ru{sub 4}(CO){sub 12}[{mu}-SCH{sub 2}CMe{sub 2}CH{sub 2}]2 (1) was transformed into two new hexaruthenium cluster complexes, Ru{sub 6}(CO){sub 13}({mu}{sub 3}-SCH{sub 2}CMe{sub 2}CH{sub 2}){sub 4} (2) and Ru{sub 6}(CO){sub 12}({mu}-SCH{sub 2}CMe{sub 2}CH{sub 2})({mu}{sub 3}-SCH{sub 2}CMe{sub 2}CH{sub 2}){sub 3}[{mu}{sub 3}-SCH{sub 2}C(Me)(CH{sub 2})CH{sub 2}] ({mu}-H) (3), that contain four and five ring-opened 3,3-dimethylthietane (3,3-DMT) ligands, respectively. In compound 3 one of the ring-opened DMT ligands has also undergone a CH activation on one of the methyl groups. Compound 2 reacts with additional 3,3-DMT at 97{degrees}C to form 3 in 18% yield. When treated with CO at 95{degrees}C (500 psi), compound 2 yielded 4,4-dimethylthiobutyrolactone and Ru{sub 3}(CO){sub 12}. It was also found that the complex Os{sub 3}(CO){sub 11-}(SCH{sub 2}CMe{sub 2}CH{sub 2}C{double_bond}O) (4) yields 4,4-dimethylthiobutyrolactone when treated with CO at 120{degrees}C (1200 psi). Crystal data for 2: space group P2{sub 1}/n, {alpha} = 22.652 (7) A, {beta} = 11.712 (2) A, c = 19.965 (6) A, {Beta} = 115.75 (2){degrees} Z = 4, 3665 reflections, R = 0.021. Crystal data for 3: space group P2{sub 1}/c, {alpha} = 17.332 (8) A, {Beta} = 14.668 (9) A, c = 19.823 (9) A, {Beta} = 91.27 (4){degrees}, Z = 4, 1875 reflections, R = 0.050. 13 refs., 2 figs., 13 refs.

  13. Forecast of a Daily Halo CME Occurrence Probability Depending on Class and Area Change of the Associated Sunspot

    NASA Astrophysics Data System (ADS)

    Lee, Kangjin; Moon, Yong-Jae; Lee, Jin-Yi

    2015-06-01

    We investigate the halo (partial and full) coronal mass ejection (CME) occurrence probability depending on class and area change of the associated sunspot using front-side halo CMEs from 1996 to 2011. We select the most halo CME-productive 14 sunspot classifications: Cao, Cko, Dai, Dao, Dko, Dki, Dkc, Eao, Eai, Eko, Eki, Ekc, Fki, and Fkc. For each class, we assign three subgroups according to sunspot class area change: "Decrease", "Steady", or "Increase". As a result, in the case of asymmetric (k) and compact (c) groups, their CME occurrence probabilities increase. We also find that the halo-CME occurrence probabilities for the "Increase" subgroups are noticeably higher than those for the other subgroups. Our results demonstrate statistically that magnetic-flux emergence or cancellation enhances CME occurrence. We expect that this model can be routinely operated to forecast the halo-CME occurrence probability.

  14. A Cluster-Analytical Approach towards Physical Activity and Eating Habits among 10-Year-Old Children

    ERIC Educational Resources Information Center

    Sabbe, Dieter; De Bourdeaudhuij, I.; Legiest, E.; Maes, L.

    2008-01-01

    The purpose was to investigate whether clusters--based on physical activity (PA) and eating habits--can be found among children, and to explore subgroups' characteristics. A total of 1725 10-year olds completed a self-administered questionnaire. K-means cluster analysis was based on the weekly quantity of vigorous and moderate PA, the excess index…

  15. Medical Problems Referred to a Care of the Elderly Physician: Insight for Future Geriatrics CME

    PubMed Central

    Lam, Robert; Gallinaro, Anna; Adleman, Jenna

    2013-01-01

    Purpose Family physicians provide the majority of elderly patient care in Canada. Many experience significant challenges in serving this cohort. This study aimed to examine the medical problems of patients referred to a care of the elderly physician, to better understand the geriatric continuing medical education (CME) needs of family doctors. Methods A retrospective chart review of patients assessed at an urban outpatient seniors’ clinic between 2003 and 2008 was conducted. Data from 104 charts were analyzed and survey follow-up with 28 of the referring family physicians was undertaken. Main outcomes include the type and frequency of medical problems actually referred to a care of the elderly physician. Clarification of future geriatric CME topics of need was also assessed. Results Preventive care issues were addressed with 67 patients. Twenty-four required discussion of advance directives. The most common medical problems encountered were osteoarthritis (42), hypertension (34), osteoporosis (32), and depression or anxiety (23). Other common problems encountered that have not been highly cited as being a target of CME included musculoskeletal and joint pain (41), diabetes (23), neck and back pain (20), obesity (11), insomnia (11), and neuropathic, fibromyalgia and “leg cramps” pain (10). The referring family physicians surveyed agreed that these were topics of need for future CME. Conclusions The findings support geriatric CME for the common medical problems encountered. Chronic pain, diabetes, obesity and insomnia continue to be important unresolved issues previously unacknowledged by physicians as CME topics of need. Future CME focusing more on process of geriatric care may also be relevant. PMID:23983827

  16. Determining CME parameters by fitting heliospheric observations: Numerical investigation of the accuracy of the methods

    NASA Astrophysics Data System (ADS)

    Lugaz, Noé; Roussev, Ilia I.; Gombosi, Tamas I.

    2011-07-01

    Transients in the heliosphere, including coronal mass ejections (CMEs) and corotating interaction regions can be imaged to large heliocentric distances by heliospheric imagers (HIs), such as the HIs onboard STEREO and SMEI onboard Coriolis. These observations can be analyzed using different techniques to derive the CME speed and direction. In this paper, we use a three-dimensional (3-D) magneto-hydrodynamic (MHD) numerical simulation to investigate one of these methods, the fitting method of Sheeley et al. (1999) and Rouillard et al. (2008). Because we use a 3-D simulation, we can determine with great accuracy the CME initial speed, its speed at 1 AU and its average transit speed as well as its size and direction of propagation. We are able to compare the results of the fitting method with the values from the simulation for different viewing angles between the CME direction of propagation and the Sun-spacecraft line. We focus on one simulation of a wide (120-140°) CME, whose initial speed is about 800 km s -1. For this case, we find that the best-fit speed is in good agreement with the speed of the CME at 1 AU, and this, independently of the viewing angle. The fitted direction of propagation is not in good agreement with the viewing angle in the simulation, although smaller viewing angles result in smaller fitted directions. This is due to the extremely wide nature of the ejection. A new fitting method, proposed to take into account the CME width, results in better agreement between fitted and actual directions for directions close to the Sun-Earth line. For other directions, it gives results comparable to the fitting method of Sheeley et al. (1999). The CME deceleration has only a small effect on the fitted direction, resulting in fitted values about 1-4° higher than the actual values.

  17. Role of paramagnetic polyconjugated clusters in lignin antioxidant activity (in vitro)

    NASA Astrophysics Data System (ADS)

    Dizhbite, T.; Ponomarenko, J.; Andersone, A.; Dobele, G.; Lauberts, M.; Krasilnikova, J.; Mironova-Ulmane, N.; Telysheva, G.

    2012-08-01

    Using physico-chemical methods (EPR, SEC, Py-GC/MS and UV/VIS spectroscopy) and wet chemical analysis, the characteristics of 6 hardwood lignins in terms of functionality, molecular weight and composition of lignin substructures were determined and considered together with the results of DPPH•, ABTS•+ and O2•- antioxidant assays with the aim to understand the relationships governing antioxidant properties of lignin. The strong positive linear correlation between lignin antioxidant capacity in the three assays used and the extent of conjugation of paramagnetic polyconjugated clusters in lignin macromolecules was found. The biological activity of the most active alkaline lignins was assessed by in vitro experiment with human blood.

  18. Detection of single unit activity from the rat vagus using cluster analysis of principal components.

    PubMed

    Horn, Charles C; Friedman, Mark I

    2003-01-30

    In vivo recordings from subdiaphragmatic vagal afferent nerves generally lack the resolution to distinguish single unit activity. Several methods for data acquisition and analysis were combined to produce a high degree of reliability in recording electrophysiological signals from gastrointestinal and hepatic afferent fibers in the rat. Recordings with low noise were achieved by paralysis of the respiratory muscles and by pinning the nerve to a recording platform. Single unit activity was isolated using principal component (PC) analysis and cluster cutting of data in multi-dimensional space (1-3 PCs). Cluster assignments were determined by a semi-automated approach using the k-means algorithm. The accuracy of single unit classification was assessed by checking inter-spike intervals (ISIs) to determine the length of the refractory period, and by cross-correlation analysis to assess whether single units were mistakenly split into more than one cluster. These analyses produced up to four isolated single units from each nerve filament (a bundle of nerve fibers), and typically it was possible to further increase yield by recording from several nerve filaments simultaneously using an array of electrodes. PMID:12573473

  19. ANISOTROPIC METAL-ENRICHED OUTFLOWS DRIVEN BY ACTIVE GALACTIC NUCLEI IN CLUSTERS OF GALAXIES

    SciTech Connect

    Kirkpatrick, C. C.; McNamara, B. R.; Cavagnolo, K. W.

    2011-04-20

    We present an analysis of the spatial distribution of metal-rich gas in 10 galaxy clusters using deep observations from the Chandra X-ray Observatory. The brightest cluster galaxies (BCGs) have experienced recent active galactic nucleus activity in the forms of bright radio emission, cavities, and shock fronts embedded in the hot atmospheres. The heavy elements are distributed anisotropically and are aligned with the large-scale radio and cavity axes. They are apparently being transported from the halo of the BCG into the intracluster medium along large-scale outflows driven by the radio jets. The radial ranges of the metal-enriched outflows are found to scale with jet power as R{sub Fe} {proportional_to} P {sup 0.42}{sub jet}, with a scatter of only 0.5 dex. The heavy elements are transported beyond the extent of the inner cavities in all clusters, suggesting that this is a long-lasting effect sustained over multiple generations of outbursts. Black holes in BCGs will likely have difficulty ejecting metal-enriched gas beyond 1 Mpc unless their masses substantially exceed 10{sup 9} M{sub sun}.

  20. Forest soil metagenome gene cluster involved in antifungal activity expression in Escherichia coli.

    PubMed

    Chung, Eu Jin; Lim, He Kyoung; Kim, Jin-Cheol; Choi, Gyung Ja; Park, Eun Jin; Lee, Myung Hwan; Chung, Young Ryun; Lee, Seon-Woo

    2008-02-01

    Using two forest soils, we previously constructed two fosmid libraries containing 113,700 members in total. The libraries were screened to select active antifungal clones using Saccharomyces cerevisiae as a target fungus. One clone from the Yuseong pine tree rhizosphere soil library, pEAF66, showed S. cerevisiae growth inhibition. Despite an intensive effort, active chemicals were not isolated. DNA sequence analysis and transposon mutagenesis of pEAF66 revealed 39 open reading frames (ORFs) and indicated that eight ORFs, probably in one transcriptional unit, might be directly involved in the expression of antifungal activity in Escherichia coli. The deduced amino acid sequences of eight ORFs were similar to those of the core genes encoding type II family polyketide synthases, such as the acyl carrier protein (ACP), ACP synthases, aminotransferase, and ACP reductase. The gene cluster involved in antifungal activity was similar in organization to the putative antibiotic production locus of Pseudomonas putida KT2440, although we could not select a similar active clone from the KT2440 genomic DNA library in E. coli. ORFs encoding ATP binding cassette transporters and membrane proteins were located at both ends of the antifungal gene cluster. Upstream ORFs encoding an IclR family response regulator and a LysR family response regulator were involved in the positive regulation of antifungal gene expression. Our results suggested the metagenomic approach as an alternative to search for novel antifungal antibiotics from unculturable soil bacteria. This is the first report of an antifungal gene cluster obtained from a soil metagenome using S. cerevisiae as a target fungus. PMID:18065615

  1. In Situ Generation of Active Molybdenum Octahedral Clusters for Photocatalytic Hydrogen Production from Water.

    PubMed

    Feliz, Marta; Puche, Marta; Atienzar, Pedro; Concepción, Patricia; Cordier, Stéphane; Molard, Yann

    2016-08-01

    The photocatalytic hydrogen evolution reaction (HER) from water under homogeneous and heterogeneous conditions is explored for the {Mo6 Br(i) 8 }(4+) cluster core based unit starting from (TBA)2 [Mo6 Br(i) 8 F(a) 6 ] (TBA=tetra-n-butylammonium; "i" and "a" refer to the face-capping inner and terminal apical ligand, respectively). The catalytic activity of {Mo6 Br(i) 8 }(4+) is enhanced by the in situ generation of [Mo6 Br(i) 8 F(a) 5 (OH)(a) ](2-) , [Mo6 Br(i) 8 F(a) 3 (OH)(a) 3 ](2-) , and [Mo6 Br(i) 8 (OH)(a) 6 ](2-) , which are identified by ESIMS, luminescence, and NMR techniques. Full substitution of F(-) by OH(-) leads to the formation of (H3 O)2 [Mo6 Br(i) 8 (OH)(a) 6 ]⋅10 H2 O; its structure was determined by single-crystal XRD. The immobilization of the active {Mo6 Br(i) 8 }(4+) onto graphene oxide (GO) surfaces enhances its stability under catalytic conditions. The catalytic activity of the resulting (TBA)2 Mo6 Br(i) 8 @GO material is improved with respect to GO, but is reduced compared to the activity under homogeneous conditions because of changes in the GO semiconducting properties as well as lower activity and/or accessibility of the anchored cluster. PMID:27314221

  2. Simulations of cosmic-ray feedback by active galactic nuclei in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Sijacki, Debora; Pfrommer, Christoph; Springel, Volker; Enßlin, Torsten A.

    2008-07-01

    Feedback processes by active galactic nuclei (AGN) appear to be a key for understanding the nature of the very X-ray luminous cool cores found in many clusters of galaxies. We investigate a numerical model for AGN feedback where for the first time a relativistic particle population in AGN-inflated bubbles is followed within a full cosmological context. In our high-resolution simulations of galaxy cluster formation, we assume that black hole accretion is accompanied by energy feedback that occurs in two different modes, depending on the accretion rate itself. At high accretion rates, a small fraction of the radiated energy is coupled thermally to the gas surrounding the quasar, while in a low-accretion state, mechanically efficient feedback in the form of hot, buoyant bubbles that are inflated by radio activity is considered. Unlike previous work, we inject a non-thermal particle population of relativistic protons into the AGN bubbles, instead of adopting a purely thermal heating. We then follow the subsequent evolution of the cosmic-ray (CR) plasma inside the bubbles, considering both its hydrodynamical interactions and dissipation processes relevant to the CR population. This permits us to analyse the impact of CR bubbles on the surrounding intracluster medium, and in particular, how this contrasts with the purely thermal case. Due to the different buoyancy of relativistic plasma and the comparatively long CR dissipation time-scale, we find substantial changes in the evolution of clusters as a result of CR feedback. In particular, the non-thermal population can provide significant pressure support in central cluster regions at low thermal temperatures, providing a natural explanation for the decreasing temperature profiles found in cool core clusters. At the same time, the morphologies of the bubbles and of the induced X-ray cavities show a striking similarity to observational findings. AGN feedback with CRs also proves efficient in regulating cluster cooling

  3. Cluster spacecraft observations of a ULF wave enhanced by Space Plasma Exploration by Active Radar (SPEAR)

    NASA Astrophysics Data System (ADS)

    Badman, S. V.; Wright, D. M.; Clausen, L. B. N.; Fear, R. C.; Robinson, T. R.; Yeoman, T. K.

    2009-09-01

    Space Plasma Exploration by Active Radar (SPEAR) is a high-latitude ionospheric heating facility capable of exciting ULF waves on local magnetic field lines. We examine an interval from 1 February 2006 when SPEAR was transmitting a 1 Hz modulation signal with a 10 min on-off cycle. Ground magnetometer data indicated that SPEAR modulated currents in the local ionosphere at 1 Hz, and enhanced a natural field line resonance with a 10 min period. During this interval the Cluster spacecraft passed over the heater site. Signatures of the SPEAR-enhanced field line resonance were present in the magnetic field data measured by the magnetometer on-board Cluster-2. These are the first joint ground- and space-based detections of field line tagging by SPEAR.

  4. Phosphorous transient enhanced diffusion suppression and activation enhancement with cluster carbon co-implantation

    SciTech Connect

    Nakashima, Yoshiki; Hamamoto, Nariaki; Nagayama, Tsutomu; Koga, Yuji; Umisedo, Sei; Kawamura, Yasunori; Hashimoto, Masahiro; Onoda, Hiroshi

    2012-11-06

    Carbon co-implantation is well known as an effective method for suppressing boron/phosphorous transient enhanced diffusion (TED). Germanium pre-amorphization implantation (PAI) is usually applied prior to carbon co-implantation for suppressing channeling tail of dopants. In this study, cluster carbon was applied instead of the combination of germanium PAI and monomer carbon co-implantation prior to phosphorous implantation. Dependence of phosphorous activation and TED on amorphous layer thickness, carbon dose, carbon distribution and substrate temperature have been investigated. Cluster carbon implantation enables thick amorphous layer formation and TED suppression at the same time and low temperature implantation enhances the ability of amorphous layer formation so that shallow junction and low Rs can be achieved without Ge implantation.

  5. Role of geometrical symmetry in thermally activated processes in clusters of interacting dipolar moments

    NASA Astrophysics Data System (ADS)

    Hovorka, O.; Barker, J.; Friedman, G.; Chantrell, R. W.

    2014-03-01

    Thermally activated magnetization decay is studied in ensembles of clusters of interacting dipolar moments by applying the master-equation formalism, as a model of thermal relaxation in systems of interacting single-domain ferromagnetic particles. Solving the associated master equation reveals a breakdown of the energy barrier picture depending on the geometrical symmetry of structures. Deviations are most pronounced for reduced symmetry and result in a strong interaction dependence of relaxation rates on the memory of system initialization. A simple two-state system description of an ensemble of clusters is developed, which accounts for the observed anomalies. These results follow from a semianalytical treatment, and are fully supported by kinetic Monte Carlo simulations.

  6. Interplay of cytoskeletal activity and lipid phase stability in dynamic protein recruitment and clustering.

    PubMed

    Gómez-Llobregat, Jordi; Buceta, Javier; Reigada, Ramon

    2013-01-01

    Recent experiments have revealed that some membrane proteins aggregate to form clusters. This type of process has been proven to be dynamic and to be actively maintained by external kinetics. Additionally, this dynamic recruiting is cholesterol- and actin-dependent, suggesting that raft organization and cytoskeleton rearrangement play a crucial role. In the present study, we propose a simple model that provides a general framework to describe the dynamical behavior of lipid-protein assemblies. Our results suggest that lipid-mediated interactions and cytoskeleton-anchored proteins contribute to the modulation of such behavior. In particular, we find a resonant condition between the membrane protein and cytoskeleton dynamics that results in the invariance of the ratio of clustered proteins that is found in in vivo experimental observations. PMID:24018870

  7. Predicting Water Activity for Complex Wastes with Solvation Cluster Equilibria (SCE) - 12042

    SciTech Connect

    Agnew, S.F.; Reynolds, J.G.; Johnston, C.T.

    2012-07-01

    Predicting an electrolyte mixture's water activity, i.e. the ratio of water vapor pressure over a solution with that of pure water, in principle reveals both boiling point and solubilities for that mixture. Better predictions of these properties helps support the ongoing missions to concentrate complex nuclear waste mixtures in order to conserve tank space and improved predictions of water activity will help. A new approach for predicting water activity, the solvation cluster equilibria (SCE) model, uses pure electrolyte water activities to predict water activity for a complex mixture of those electrolytes. An SCE function based on electrolyte hydration free energy and a standard Debye- Hueckel (DH) charge compression fits each pure electrolyte's water activity with three parameters. Given these pure electrolyte water activities, the SCE predicts any mixture water activity over a large range of concentration with an additional parameter for each mixture vector, the multinarity. In contrast to ionic strength, which scales with concentration, multinarity is related to the relative proportion of electrolytes in a mixture and can either increase or decrease the water activity prediction over a broad range of concentration for that mixture. The SCE model predicts water activity for complex electrolyte mixtures based on the water activities of pure electrolytes. Three parameter SCE functions fit the water activities of pure electrolytes and along with a single multinarity parameter for each mixture vector then predict the mixture water activity. Predictions of water activity can in principle predict solution electrolyte activity and this relationship will be explored in the future. Predicting electrolyte activities for complex mixtures provides a means of determining solubilities for each electrolyte. Although there are a number of reports [9, 10, 11] of water activity models for pure and binary mixtures of electrolytes, none of them compare measured versus calculated

  8. Plasmoid instability in a large post-CME current sheet system

    NASA Astrophysics Data System (ADS)

    Guo, L.; Bhattacharjee, A.; Huang, Y.; CenterIntegrated Computation; Analysis of Reconnection; Turbulence

    2011-12-01

    Solar flares and CME that cause violent space weather change have been studied for years. The standard model suggests that there is a current sheet connecting the CME and the site of the post-CME flare after the eruption, but understanding of the detailed physical mechanism of dynamical processes in the current sheet remains incomplete. Recently, the secondary plasmoid instabilities of large scale current sheet in high Lundquist number environment such as solar corona and the change of magnetic topology in such a current sheet system has become a subject of great interest (Bhattacharjee et al. 2009). In our work, we study a post-CME current sheet via both observation and simulation. We use SOHO/LASCO observations of a fast halo CME as well as a slow CME. After the fast halo CME event on January 8, 2002, we observe a long, thin current sheet which connects the CME to a flare site on the surface of the sun. In this current sheet we identify over 60 bright plasmoid-like blobs in 39 hours. In the slow CME event on June 25, 2005, we observe 32 such blobs in 18 hours after the formation of the current sheet. We simulate both cases using high-Lundquist-number resistive MHD simulations of the model of Lin & Forbes (2000), and demonstrate that the distribution of plasmoid size in both cases appears to conform well to a distribution function that is independent of the Lundquist number and predicted by theory. The average observed plasmoid speed in both cases is a fraction of the typical Alfven speed, qualitatively consistent with the simulations. Thus, we propose that these observations can be plausibly accounted for by the plasmoid instability of the large-scale current sheet. The observed bright blobs are probably evidence of large-scale plasmoids, and their behavior appears to be qualitatively consistent with high-Lundquist-number MHD simulations.
    observation case summary

  9. A new experimental setup for high-pressure catalytic activity measurements on surface deposited mass-selected Pt clusters

    SciTech Connect

    Watanabe, Yoshihide; Isomura, Noritake

    2009-09-15

    A new experimental setup to study catalytic and electronic properties of size-selected clusters on metal oxide substrates from the viewpoint of cluster-support interaction and to formulate a method for the development of heterogeneous catalysts such as automotive exhaust catalysts has been developed. The apparatus consists of a size-selected cluster source, a photoemission spectrometer, a scanning tunneling microscope (STM), and a high-pressure reaction cell. The high-pressure reaction cell measurements provided information on catalytic properties in conditions close to practical use. The authors investigated size-selected platinum clusters deposited on a TiO{sub 2}(110) surface using a reaction cell and STM. Catalytic activity measurements showed that the catalytic activities have a cluster-size dependency.

  10. Dependence of Sunspot Properties on Flare Occurrence and Flare-CME Association

    NASA Astrophysics Data System (ADS)

    Yang, Ya-Hui

    2015-04-01

    Previous studies showed that the intense flares tend to erupt from the large sunspot region with complex magnetic configuration and strong magnetic field. However, note that not all the active regions (ARs) classified as βγδ would produce X-class flares. To clarify the significance of sunspot properties on solar explosive events, we reexamine the dependence of flare magnitude on sunspot size and magnetic type during 1996-2014 based on the report of NOAA Solar Region Summary and the measurements of GOES soft X-ray flux. In particular, we focus on the βγδ-type ARs to relate the flare productivity to the sunspot area and magnetic field strength by means of the line-of-sight magnetograms from SOHO/MDI and SDO/HMI. Two flare-productive ARs, 10486 and 12192, with βγδ magnetic configuration during most periods of their disk passages are further investigated to characterize the sunspots and flare-CME association.

  11. The Solar Corona and a CME at the 2010 Total Eclipse

    NASA Astrophysics Data System (ADS)

    Pasachoff, Jay M.; Rusin, V.; Druckmüllerová, H.; Saniga, M.; Lu, M.; Malamut, C.; Seaton, D. B.; Golub, L.; Engell, A. J.; Hill, S. W.; Lucas, R.

    2011-05-01

    The 11 July 2010 total solar eclipse was observed on the ground from French Polynesia and, 83 minutes later, from Easter Island, and near-simultaneous images were made with spacecraft instruments including AIA/SDO, HMI/SDO, EUVI/STEREO, SWAP/PROBA2, EIT/SOHO, and LASCO/SOHO. We report on changes in the corona detectable with high-resolution image processing of the ground-based eclipse coronal imaging, including two CME's that were seen to evolve. We compare with the spacecraft images to give a complete depiction of coronal structure at the time of the eclipse, which corresponded to a low but rising phase of the solar-activity cycle. We acknowledge the support of NASA's MSFC NNX10AK47A, NSF REU AST-1005024 with DoD ASSURE, VEGA 2/0098/10 of the Slovak Acad. Sci, 205/09/1469 of the Czech Science Foundation, PRODEX C90345 of ESA/BELSPO, FP7/2007-2013/218816 SOTERIA, Lockheed Martin; for equipment: Nikon Professional Services, ASTELCO Systems GmbH (Germany), and National Geographic Society's Photographic Division; and colleagues Y.-M. Wang (NRL), S. Habbal (U. Hawaii), H. Lanteires (Tatakoto), and J. Kern (Carnegie Obs.).

  12. Post Alpbach-summerschool project: CARRINGTON MISSION FOR CME DETECTION TO IMPROVE SPACE WEATHER FORECAST

    NASA Astrophysics Data System (ADS)

    Scheucher, Markus; Urbar, Jaroslav; Musset, Sophie; Andersson, Viktor; Gini, Francesco; Gorski, Jedrzej; Jüstel, Peter; Kiefer, René; Lee, Arrow; Meskers, Arjan; Miles, Oscar; Perakis, Nikolas; Rußwurm, Michael; Scully, Stephen; Seifert, Bernhard; Sorba, Arianna

    2014-05-01

    The effects of solar activity, especially Coronal Mass Ejections (CMEs), on Earth- and satellite-based systems are well-known and can cause major damage to space-dependent infrastructure. The main problem in current space weather forecasting is the inability to determine necessary forecast parameters of CMEs and Corotating Interaction Regions (CIRs) early enough to react. We present the design for a novel space mission consisting of two spacecraft that is aimed to perform stereoscopic measurements on Earth-directed CMEs and in-situ measurements of CIRs. The magnetic field orientation and structure of CMEs will be measured close to the Sun, using spectro-polarimetry. Geoeffectiveness will be derived by remote sensing the CMEs magnetic field at 0.64AU from the Sun, determining the full magnetic field vector of a CME. This will be achieved by the novel concept of measuring its polarising effects on spacecraft to spacecraft laser beams based upon heterodyne interferometry. Overall structure and trajectory of CMEs will also be monitored by heliospheric imagers and in-situ plasma instruments. To achieve the mission objectives, the orbit is heliocentric at 1AU with a separation angle from the Earth of ±50°. The operational mission lifetime is 6 years with a proposed 6 year extension. If implemented, Carrington will serve as a forecast system which will significantly improve the minimum forecast time for the fastest CMEs with 2000 km/s, from 13 minutes based on current L1 satellites, to around 3 hours.

  13. The CORIMP CME Catalogue: Automatically Detecting and Tracking CMEs in Coronagraph Data

    NASA Astrophysics Data System (ADS)

    Byrne, Jason; Morgan, H.; Habbal, S. R.

    2012-05-01

    Studying CMEs in coronagraph data can be challenging due to their diffuse structure and transient nature, and user-specific biases may be introduced through visual inspection of the images. The large amount of data available from the SOHO and STEREO missions also makes manual cataloguing of CMEs tedious, and so a robust method of detection and analysis is required. This has led to the development of automated CME detection and cataloguing packages such as CACTus, SEEDS and ARTEMIS. Here we present the development of the CORIMP (coronal image processing) Catalogue: a new, automated, multiscale, CME detection and tracking catalogue, that overcomes many of the drawbacks of current catalogues. It works by first employing a dynamic CME separation technique to remove the static background, and then characterizing CME structure via a multiscale edge-detection algorithm. The detections are chained through time to determine the CME kinematics and morphological changes as it propagates across the plane-of-sky. The effectiveness of the method is demonstrated by its application to a selection of SOHO/LASCO and STEREO/SECCHI images, as well as to synthetic coronagraph images created from a model corona with a variety of CMEs. These algorithms are being applied to the whole LASCO and SECCHI datasets, and a CORIMP catalogue of results will soon be available to the community.

  14. Teaching tools useful to understand the Space Weather, through kinematic analysis of some CME

    NASA Astrophysics Data System (ADS)

    Amazo-Gomez, Eliana

    The earth is a planet belonging to a medium dynamic, interacting, is not restricted a closed system, but it is affected by her multiple external phenomena, storms geomagnetic, coronal mass ejections, spatial tremors, changes in the environment plasma and magnetic fields near the sun and affecting the planet and overall radiation from other parts of space are subject study space weather. In this work I teach to my school students some tools and main ideas about some things about the Space Weather, through the analysis to five CME events and the localization the CMEs sources. We use Stereo and ISWA tools and datasets, also SOHO and STEREO Within the missions (Cor 1.2, HI 1.2, of A & B and SOHO spacecraft/LASCO C2 & C3), we proceed to calibrate the data, and make movies of the CME seen from of all 3 spacecrafts, then we can estimate the CME front (position), calculate the velocity of the CME and plot the velocity/time diagram, create J-plots, and finally, we Infer the velocity of the CME out of the J-plot. The coronal mass ejections measures were compared with records and this got us some a description of the stage in which the dynamic system is they belong to the earth and the sun, the idea of this work was show and describe some of the measurements that are used to develop the study of Space Weather.

  15. Strong coronal deflection of a CME and its interplanetary evolution to Earth and Mars

    NASA Astrophysics Data System (ADS)

    Möstl, Christian; Rollett, Tanja; Frahm, Rudy A.; Liu, Ying D.; Long, David M.; Colaninno, Robin C.; Reiss, Martin A.; Temmer, Manuela; Farrugia, Charles J.; Posner, Arik; Dumbovic, Mateja; Janvier, Miho; Demoulin, Pascal; Boakes, Peter; Devos, Andy; Kraaikamp, Emil; Mays, Mona L.; Vrsnak, Bojan

    2015-04-01

    We discuss multipoint imaging and in situ observations of the coronal mass ejection (CME) on January 7 2014 which resulted in a major false alarm. While the source region was almost at disk center facing Earth, the eruption was strongly deflected in the corona, and in conjunction with its particular orientation this CME missed Earth almost entirely, leading to no significant geomagnetic effects. We demonstrate this by a synthesis of data from 7 different heliospheric and planetary space missions (STEREO-A/B, SOHO, SDO, Wind, Mars Express, Mars Science Laboratory). The CMEs ecliptic part was deflected by 37 ± 10° in heliospheric longitude, a value larger than previously thought. Multipoint in situ observations at Earth and Mars confirm the deflection, and are consistent with an elliptical interplanetary shock shape of aspect ratio 1.4 ± 0.4. We also discuss our new method, the Ellipse Evolution (ElEvo) model, which allows us to optimize the global shape of the CME shock with multipoint in situ observations of the interplanetary CME arrival. ElEvo, which is an extension to the Drag-Based-Model by Vrsnak et al., may also be used for real time space weather forecasting. The presented results enhance our understanding of CME deflection and shape, which are fundamental ingredients for improving space weather forecasts.

  16. C-H Bond Activation by Early Transition Metal Carbide Cluster Anion MoC3 (-).

    PubMed

    Li, Zi-Yu; Hu, Lianrui; Liu, Qing-Yu; Ning, Chuan-Gang; Chen, Hui; He, Sheng-Gui; Yao, Jiannian

    2015-12-01

    Although early transition metal (ETM) carbides can activate CH bonds in condensed-phase systems, the electronic-level mechanism is unclear. Atomic clusters are ideal model systems for understanding the mechanisms of bond activation. For the first time, CH activation of a simple alkane (ethane) by an ETM carbide cluster anion (MoC3 (-) ) under thermal-collision conditions has been identified by using high-resolution mass spectrometry, photoelectron imaging spectroscopy, and high-level quantum chemical calculations. Dehydrogenation and ethene elimination were observed in the reaction of MoC3 (-) with C2 H6 . The CH activation follows a mechanism of oxidative addition that is much more favorable in the carbon-stabilized low-spin ground electronic state than in the high-spin excited state. The reaction efficiency between the MoC3 (-) anion and C2 H6 is low (0.23±0.05) %. A comparison between the anionic and a highly efficient cationic reaction system (Pt(+) +C2 H6 ) was made. It turned out that the potential-energy surfaces for the entrance channels of the anionic and cationic reaction systems can be very different. PMID:26490554

  17. The RACE-OC project: Rotation and ACtivity Evolution in Open Clusters .

    NASA Astrophysics Data System (ADS)

    Messina, S.

    The RACE-OC (Rotation and ACtivity Evolution in Open Clusters) is a project aimed at studying the evolution of rotation and magnetic activity of the late-type members belonging to open clusters with an age in the range from about 1 to 500 Myr. In late-type stars rotation and solar-like magnetic activity are closely inter-related. In fact, presence and level of stellar magnetic activity depend on rotation. On the other hand, magnetic activity influences the evolution of the angular momentum and determines the atmospheric structure from the PMS to Post-MS evolutionary stages (Dorren & Guinan \\cite{Dorren94}; Guinan et al. \\cite{Guinan01}). Studies of the rotation and magnetic activity evolution versus time are particularly relevant to 1) determine the radiative and magnetic properties of the young Sun; 2) study its evolution history to the present; 3) construct irradiance tables to be used to model paleo-planetary atmospheres. Our aim is to describe the evolution versus time of either the stellar angular momentum and magnetic activity, by inferring from observational data accurate empirical relations between global stellar properties, rotation and activity manifestations at different atmospheric levels to be compared to current stellar evolution and hydromagnetic dynamo models. The multiband CCD photometric observations have been so far carried out with the 0.6m REM (Rapid Eye Mount) telescope (La Silla, Chile) of INAF; the 2m HCT (Himalayan Chandra Telescope) of IIA, the 1.3m Cassegrain telescope of Skinakas Observatory (University of Crete) and, finally, the 1.3m RCT (Robotic Controlled Telescope, Arizona) of Villanova University.

  18. Modeling active galactic nucleus feedback in cool-core clusters: The formation of cold clumps

    SciTech Connect

    Li, Yuan; Bryan, Greg L.

    2014-07-10

    We perform high-resolution (15-30 pc) adaptive mesh simulations to study the impact of momentum-driven active galactic nucleus (AGN) feedback in cool-core clusters, focusing in this paper on the formation of cold clumps. The feedback is jet-driven with an energy determined by the amount of cold gas within 500 pc of the super-massive black hole. When the intracluster medium in the core of the cluster becomes marginally stable to radiative cooling, with the thermal instability to the free-fall timescale ratio t{sub TI}/t{sub ff} < 3-10, cold clumps of gas start to form along the propagation direction of the AGN jets. By tracing the particles in the simulations, we find that these cold clumps originate from low entropy (but still hot) gas that is accelerated by the jet to outward radial velocities of a few hundred km s{sup –1}. This gas is out of hydrostatic equilibrium and so can cool. The clumps then grow larger as they decelerate and fall toward the center of the cluster, eventually being accreted onto the super-massive black hole. The general morphology, spatial distribution, and estimated Hα morphology of the clumps are in reasonable agreement with observations, although we do not fully replicate the filamentary morphology of the clumps seen in the observations, probably due to missing physics.

  19. Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants.

    PubMed

    Messina, Marco S; Axtell, Jonathan C; Wang, Yiqun; Chong, Paul; Wixtrom, Alex I; Kirlikovali, Kent O; Upton, Brianna M; Hunter, Bryan M; Shafaat, Oliver S; Khan, Saeed I; Winkler, Jay R; Gray, Harry B; Alexandrova, Anastassia N; Maynard, Heather D; Spokoyny, Alexander M

    2016-06-01

    We report a discovery that perfunctionalized icosahedral dodecaborate clusters of the type B12(OCH2Ar)12 (Ar = Ph or C6F5) can undergo photo-excitation with visible light, leading to a new class of metal-free photooxidants. Excitation in these species occurs as a result of the charge transfer between low-lying orbitals located on the benzyl substituents and an unoccupied orbital delocalized throughout the boron cluster core. Here we show how these species, photo-excited with a benchtop blue LED source, can exhibit excited-state reduction potentials as high as 3 V and can participate in electron-transfer processes with a broad range of styrene monomers, initiating their polymerization. Initiation is observed in cases of both electron-rich and electron-deficient styrene monomers at cluster loadings as low as 0.005 mol%. Furthermore, photo-excitation of B12(OCH2C6F5)12 in the presence of a less activated olefin such as isobutylene results in the production of highly branched poly(isobutylene). This work introduces a new class of air-stable, metal-free photo-redox reagents capable of mediating chemical transformations. PMID:27186856

  20. Identification of novel mureidomycin analogues via rational activation of a cryptic gene cluster in Streptomyces roseosporus NRRL 15998

    PubMed Central

    Jiang, Lingjuan; Wang, Lu; Zhang, Jihui; Liu, Hao; Hong, Bin; Tan, Huarong; Niu, Guoqing

    2015-01-01

    Antimicrobial agents are urgently needed to tackle the growing threat of antibiotic-resistant pathogens. An important source of new antimicrobials is the large repertoire of cryptic gene clusters embedded in microbial genomes. Genome mining revealed a napsamycin/mureidomycin biosynthetic gene cluster in the chromosome of Streptomyces roseosporus NRRL 15998. The cryptic gene cluster was activated by constitutive expression of a foreign activator gene ssaA from sansanmycin biosynthetic gene cluster of Streptomyces sp. strain SS. Expression of the gene cluster was verified by RT-PCR analysis of key biosynthetic genes. The activated metabolites demonstrated potent inhibitory activity against the highly refractory pathogen Pseudomonas aeruginosa, and characterization of the metabolites led to the discovery of eight acetylated mureidomycin analogues. To our surprise, constitutive expression of the native activator gene SSGG_02995, a ssaA homologue in S. roseosporus NRRL 15998, has no beneficial effect on mureidomycin stimulation. This study provides a new way to activate cryptic gene cluster for the acquisition of novel antibiotics and will accelerate the exploitation of prodigious natural products in Streptomyces. PMID:26370924

  1. MLSO Mark III K-Coronameter Observations of the CME Rate from 1989 - 1996

    NASA Astrophysics Data System (ADS)

    St. Cyr, O. C.; Flint, Q. A.; Xie, H.; Webb, D. F.; Burkepile, J. T.; Lecinski, A. R.; Quirk, C.; Stanger, A. L.

    2015-10-01

    We report here an attempt to fill the 1990 - 1995 gap in the CME rate using the Mauna Loa Solar Observatory's Mark III (Mk3) K-coronameter. The Mk3 instrument observed routinely several hours most days beginning in 1980 until it was upgraded to Mk4 in 1999. We describe the statistical properties of the CMEs detected during 1989 - 1996, and we determine a CME rate for each of those years. Since spaceborne coronagraphs have more complete duty cycles than a ground-based instrument at a single location, we compare the Mk3-derived CME rate from 1989 with the rate from the SMM C/P coronagraph, and from 1996 with the rate from the SOHO LASCO coronagraphs.

  2. Stereoscopic Analysis of STEREO/SECCHI Data for CME Trajectory Determination

    NASA Technical Reports Server (NTRS)

    Liewer, P. C.; Hall, J. R.; Howard, R. A.; DeJong, E. M.; Thompson, W. T.; Thernisten, A.

    2010-01-01

    The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) coronagraphs on the twin Solar TErrestrial RElations Observatory (STEREO) spacecraft provide simultaneous views of the corona and coronal mass ejections from two view points. Here, we analyze simultaneous image pairs using the technique of tie-pointing and triangulation (T&T) to determine the three-dimensional trajectory of seven coronal mass ejections (CMEs). The bright leading edge of a CME seen in coronagraph images results from line-of-sight integration through the CME front; the two STEREO coronagraphs see different apparent leading edges, leading to a systematic error in its three-dimensional reconstruction. We analyze this systematic error using a simple geometric model of a CME front. We validate the technique and analysis by comparing T&T trajectory determinations for seven CMEs with trajectories determined by Thernisien et al. (2009) using a forward modeling technique not susceptible to this systematic effect.

  3. Clustered mutations in hominid genome evolution are consistent with APOBEC3G enzymatic activity.

    PubMed

    Pinto, Yishay; Gabay, Orshay; Arbiza, Leonardo; Sams, Aaron J; Keinan, Alon; Levanon, Erez Y

    2016-05-01

    The gradual accumulation of mutations by any of a number of mutational processes is a major driving force of divergence and evolution. Here, we investigate a potentially novel mutational process that is based on the activity of members of the AID/APOBEC family of deaminases. This gene family has been recently shown to introduce-in multiple types of cancer-enzyme-induced clusters of co-occurring somatic mutations caused by cytosine deamination. Going beyond somatic mutations, we hypothesized that APOBEC3-following its rapid expansion in primates-can introduce unique germline mutation clusters that can play a role in primate evolution. In this study, we tested this hypothesis by performing a comprehensive comparative genomic screen for APOBEC3-induced mutagenesis patterns across different hominids. We detected thousands of mutation clusters introduced along primate evolution which exhibit features that strongly fit the known patterns of APOBEC3G mutagenesis. These results suggest that APOBEC3G-induced mutations have contributed to the evolution of all genomes we studied. This is the first indication of site-directed, enzyme-induced genome evolution, which played a role in the evolution of both modern and archaic humans. This novel mutational mechanism exhibits several unique features, such as its higher tendency to mutate transcribed regions and regulatory elements and its ability to generate clusters of concurrent point mutations that all occur in a single generation. Our discovery demonstrates the exaptation of an anti-viral mechanism as a new source of genomic variation in hominids with a strong potential for functional consequences. PMID:27056836

  4. Clustered mutations in hominid genome evolution are consistent with APOBEC3G enzymatic activity

    PubMed Central

    Pinto, Yishay; Gabay, Orshay; Arbiza, Leonardo; Sams, Aaron J.; Keinan, Alon

    2016-01-01

    The gradual accumulation of mutations by any of a number of mutational processes is a major driving force of divergence and evolution. Here, we investigate a potentially novel mutational process that is based on the activity of members of the AID/APOBEC family of deaminases. This gene family has been recently shown to introduce—in multiple types of cancer—enzyme-induced clusters of co-occurring somatic mutations caused by cytosine deamination. Going beyond somatic mutations, we hypothesized that APOBEC3—following its rapid expansion in primates—can introduce unique germline mutation clusters that can play a role in primate evolution. In this study, we tested this hypothesis by performing a comprehensive comparative genomic screen for APOBEC3-induced mutagenesis patterns across different hominids. We detected thousands of mutation clusters introduced along primate evolution which exhibit features that strongly fit the known patterns of APOBEC3G mutagenesis. These results suggest that APOBEC3G-induced mutations have contributed to the evolution of all genomes we studied. This is the first indication of site-directed, enzyme-induced genome evolution, which played a role in the evolution of both modern and archaic humans. This novel mutational mechanism exhibits several unique features, such as its higher tendency to mutate transcribed regions and regulatory elements and its ability to generate clusters of concurrent point mutations that all occur in a single generation. Our discovery demonstrates the exaptation of an anti-viral mechanism as a new source of genomic variation in hominids with a strong potential for functional consequences. PMID:27056836

  5. Effects of algorithm for diagnosis of active labour: cluster randomised trial

    PubMed Central

    Hundley, Vanora; Dowding, Dawn; Bland, J Martin; McNamee, Paul; Greer, Ian; Styles, Maggie; Barnett, Carol A; Scotland, Graham; Niven, Catherine

    2008-01-01

    Objective To compare the effectiveness of an algorithm for diagnosis of active labour in primiparous women with standard care in terms of maternal and neonatal outcomes. Design Cluster randomised trial. Setting Maternity units in Scotland with at least 800 annual births. Participants 4503 women giving birth for the first time, in 14 maternity units. Seven experimental clusters collected data from a baseline sample of 1029 women and a post-implementation sample of 896 women. The seven control clusters had a baseline sample of 1291 women and a post-implementation sample of 1287 women. Intervention Use of an algorithm by midwives to assist their diagnosis of active labour, compared with standard care. Main outcomes Primary outcome: use of oxytocin for augmentation of labour. Secondary outcomes: medical interventions in labour, admission management, and birth outcome. Results No significant difference was found between groups in percentage use of oxytocin for augmentation of labour (experimental minus control, difference=0.3, 95% confidence interval −9.2 to 9.8; P=0.9) or in the use of medical interventions in labour. Women in the algorithm group were more likely to be discharged from the labour suite after their first labour assessment (difference=−19.2, −29.9 to −8.6; P=0.002) and to have more pre-labour admissions (0.29, 0.04 to 0.55; P=0.03). Conclusions Use of an algorithm to assist midwives with the diagnosis of active labour in primiparous women did not result in a reduction in oxytocin use or in medical intervention in spontaneous labour. Significantly more women in the experimental group were discharged home after their first labour ward assessment. Trial registration Current Controlled Trials ISRCTN00522952. PMID:19064606

  6. On the apparent clustering of clonal albumin production and enzyme activity levels.

    PubMed

    Thaler, H T; Braun, H I

    1984-12-01

    This communication is a critique of a novel, but inappropriate, use of the correlation coefficient to demonstrate the clustering of biological activity levels about a purported geometric progression. The data are re-examined by using a Fourier analysis approach to test for periodicity on a logarithmic scale; this approach follows from the methods of Kendall (1974, Philosophical Transactions of the Royal Society, Series A 276, 231-266) and Fisher (1929, Proceedings of the Royal Statistical Society, Series A 125, 54-59). PMID:6534411

  7. Destruction of giant cluster-like vesicles by an ultrasonically activated device

    NASA Astrophysics Data System (ADS)

    Yahagi, Ryosuke; Yoshida, Kenji; Zhang, Yiting; Ebata, Masahiko; Toyota, Taro; Yamaguchi, Tadashi; Hayashi, Hideki

    2016-07-01

    In this paper, we propose a technically simple method of destroying a tissue marker composed of giant cluster-like vesicles (GCVs) to facilitate laparoscopic surgeries; the method releases various biological tracers contained in GCVs. An ultrasonically activated device (USAD) emitting 55.5 kHz ultrasound was employed for this purpose. Optical microscopy and fluorospectrophotometry revealed the destruction of GCVs after ultrasound irradiation when the blade tip was set 1.0 mm or closer to, but not directly in contact with, a GCV-containing cell. This means that USAD could be safely used for destroying this GCV tissue marker in clinical settings.

  8. Voltage clustering in redox-active ligand complexes: mitigating electronic communication through choice of metal ion.

    PubMed

    Zarkesh, Ryan A; Ichimura, Andrew S; Monson, Todd C; Tomson, Neil C; Anstey, Mitchell R

    2016-06-14

    The redox-active bis(imino)acenapthene (BIAN) ligand was used to synthesize homoleptic aluminum, chromium, and gallium complexes of the general formula (BIAN)3M. The resulting compounds were characterized using X-ray crystallography, NMR, EPR, magnetic susceptibility and cyclic voltammetry measurements and modeled using both DFT and ab initio wavefunction calculations to compare the orbital contributions of main group elements and transition metals in ligand-based redox events. Complexes of this type have the potential to improve the energy density and electrolyte stability of grid-scale energy storage technologies, such as redox flow batteries, through thermodynamically-clustered redox events. PMID:26998892

  9. Voltage clustering in redox-active ligand complexes: mitigating electronic communication through choice of metal ion

    DOE PAGESBeta

    Zarkesh, Ryan A.; Ichimura, Andrew S.; Monson, Todd C.; Tomson, Neil C.; Anstey, Mitchell R.

    2016-02-01

    We used the redox-active bis(imino)acenapthene (BIAN) ligand to synthesize homoleptic aluminum, chromium, and gallium complexes of the general formula (BIAN)3M. The resulting compounds were characterized using X-ray crystallography, NMR, EPR, magnetic susceptibility and cyclic voltammetry measurements and modeled using both DFT and ab initio wavefunction calculations to compare the orbital contributions of main group elements and transition metals in ligand-based redox events. Ultimately, complexes of this type have the potential to improve the energy density and electrolyte stability of grid-scale energy storage technologies, such as redox flow batteries, through thermodynamically-clustered redox events.

  10. The Solar Stormwatch CME catalogue: Results from the first space weather citizen science project

    NASA Astrophysics Data System (ADS)

    Barnard, L.; Scott, C.; Owens, M.; Lockwood, M.; Tucker-Hood, K.; Thomas, S.; Crothers, S.; Davies, J. A.; Harrison, R.; Lintott, C.; Simpson, R.; O'Donnell, J.; Smith, A. M.; Waterson, N.; Bamford, S.; Romeo, F.; Kukula, M.; Owens, B.; Savani, N.; Wilkinson, J.; Baeten, E.; Poeffel, L.; Harder, B.

    2014-12-01

    Solar Stormwatch was the first space weather citizen science project, the aim of which is to identify and track coronal mass ejections (CMEs) observed by the Heliospheric Imagers aboard the STEREO satellites. The project has now been running for approximately 4 years, with input from >16,000 citizen scientists, resulting in a data set of >38,000time-elongation profiles of CME trajectories, observed over 18 preselected position angles. We present our method for reducing this data set into a CME catalogue. The resulting catalogue consists of 144 CMEs over the period January 2007 to February 2010, of which 110 were observed by STEREO-A and 77 were observed by STEREO-B. For each CME, the time-elongation profiles generated by the citizen scientists are averaged into a consensus profile along each position angle that the event was tracked. We consider this catalogue to be unique, being at present the only citizen science-generated CME catalogue, tracking CMEs over an elongation range of 4° out to a maximum of approximately 70°. Using single spacecraft fitting techniques, we estimate the speed, direction, solar source region, and latitudinal width of each CME. This shows that at present, the Solar Stormwatch catalogue (which covers only solar minimum years) contains almost exclusively slow CMEs, with a mean speed of approximately 350 km s-1. The full catalogue is available for public access at www.met.reading.ac.uk/~spate/solarstormwatch. This includes, for each event, the unprocessed time-elongation profiles generated by Solar Stormwatch, the consensus time-elongation profiles, and a set of summary plots, as well as the estimated CME properties.

  11. [FeFe]-Hydrogenase with Chalcogenide Substitutions at the H-Cluster Maintains Full H2 Evolution Activity.

    PubMed

    Noth, Jens; Esselborn, Julian; Güldenhaupt, Jörn; Brünje, Annika; Sawyer, Anne; Apfel, Ulf-Peter; Gerwert, Klaus; Hofmann, Eckhard; Winkler, Martin; Happe, Thomas

    2016-07-11

    The [FeFe]-hydrogenase HYDA1 from Chlamydomonas reinhardtii is particularly amenable to biochemical and biophysical characterization because the H-cluster in the active site is the only inorganic cofactor present. Herein, we present the complete chemical incorporation of the H-cluster into the HYDA1-apoprotein scaffold and, furthermore, the successful replacement of sulfur in the native [4FeH ] cluster with selenium. The crystal structure of the reconstituted pre-mature HYDA1[4Fe4Se]H protein was determined, and a catalytically intact artificial H-cluster variant was generated upon in vitro maturation. Full hydrogen evolution activity as well as native-like composition and behavior of the redesigned enzyme were verified through kinetic assays, FTIR spectroscopy, and X-ray structure analysis. These findings reveal that even a bioinorganic active site with exceptional complexity can exhibit a surprising level of compositional plasticity. PMID:27214763

  12. NanoCluster Beacons as Reporter Probes in Rolling Circle Enhanced Enzyme Activity Detection†

    PubMed Central

    Juul, Sissel; Obliosca, Judy M.; Liu, Cong; Liu, Yen-Liang; Chen, Yu-An; Imphean, Darren M.; Knudsen, Birgitta R.; Ho, Yi-Ping; Leong, Kam W.; Yeh, Hsin-Chih

    2015-01-01

    As a newly developed assay for the detection of endogenous enzyme activity at the single-catalytic-event level, Rolling Circle Enhanced Enzyme Activity Detection (REEAD) has been used to measure enzyme activity in both single human cells and malaria-causing parasites, Plasmodium sp.. Current REEAD assays rely on organic dye-tagged linear DNA probes to report the rolling circle amplification products (RCPs), the cost of which may hinder the widespread use of REEAD. Here we show that a new class of activatable probes, NanoCluster Beacons (NCBs), can simplify the REEAD assays. Easily prepared without any need for purification and capable of large fluorescence enhancement upon hybridization, NCBs are cost-effective and sensitive. Compared to conventional fluorescent probes, NCBs are also more photostable. As demonstrated in reporting the human topoisomerases I (hTopI) cleavage-ligation reaction, the proposed NCBs suggest a read-out format attractive for future REEAD-based diagnostics. PMID:25901841

  13. Overproduction of Ristomycin A by Activation of a Silent Gene Cluster in Amycolatopsis japonicum MG417-CF17

    PubMed Central

    Spohn, Marius; Kirchner, Norbert; Kulik, Andreas; Jochim, Angelika; Wolf, Felix; Muenzer, Patrick; Borst, Oliver; Gross, Harald; Wohlleben, Wolfgang

    2014-01-01

    The emergence of antibiotic-resistant pathogenic bacteria within the last decades is one reason for the urgent need for new antibacterial agents. A strategy to discover new anti-infective compounds is the evaluation of the genetic capacity of secondary metabolite producers and the activation of cryptic gene clusters (genome mining). One genus known for its potential to synthesize medically important products is Amycolatopsis. However, Amycolatopsis japonicum does not produce an antibiotic under standard laboratory conditions. In contrast to most Amycolatopsis strains, A. japonicum is genetically tractable with different methods. In order to activate a possible silent glycopeptide cluster, we introduced a gene encoding the transcriptional activator of balhimycin biosynthesis, the bbr gene from Amycolatopsis balhimycina (bbrAba), into A. japonicum. This resulted in the production of an antibiotically active compound. Following whole-genome sequencing of A. japonicum, 29 cryptic gene clusters were identified by genome mining. One of these gene clusters is a putative glycopeptide biosynthesis gene cluster. Using bioinformatic tools, ristomycin (syn. ristocetin), a type III glycopeptide, which has antibacterial activity and which is used for the diagnosis of von Willebrand disease and Bernard-Soulier syndrome, was deduced as a possible product of the gene cluster. Chemical analyses by high-performance liquid chromatography and mass spectrometry (HPLC-MS), tandem mass spectrometry (MS/MS), and nuclear magnetic resonance (NMR) spectroscopy confirmed the in silico prediction that the recombinant A. japonicum/pRM4-bbrAba synthesizes ristomycin A. PMID:25114137

  14. Role of Ambient Solar Wind Conditions in CME evolution (P21)

    NASA Astrophysics Data System (ADS)

    Jadav, R.; Jadeja, A. K.; Iyer, K. N.

    2006-11-01

    ipsraj@yahoo.com Solar events are mainly responsible for producing storms at the Earth. Coronal Mass Ejection (CME) is a major cause for this. In this paper, Coronal Mass Ejections occurred during 1998-2004 are studied. Ambient solar wind does play some role in determining the effect of a CME. The effects produced at the Earth during the period 1999 2004 are considered and an attempt has been made to understand the role of ambient solar wind. This is to draw some conclusion about how some of the events become geo- effective.

  15. The analysis of CME on 18 June 2000 and the associated radio emission

    NASA Astrophysics Data System (ADS)

    Wang, M.; Xie, R. X.

    A small flare near the solar limb occurred on 18 June 2000 This flare associated with a short duration radio burst in the micro-wavelength In the metric bands the radio burst wear also short but very complex which was consist of fast drifting structure type III bursts and slow drifting structure type II burst The SXR data showed that this flare was impulsive followed with a gradual phase The image radio observation showed the bright structure moving along the direction of the CME s The associated CME was very significant and typical with high velocity larger than 600km s

  16. Cosmological Studies with Galaxy Clusters, Active Galactic Nuclei, and Strongly Lensed Quasars

    NASA Astrophysics Data System (ADS)

    Rumbaugh, Nicholas Andrew

    The large-scale structure (LSS) of the universe provides scientists with one of the best laboratories for studying Lambda Cold Dark Matter (LambdaCDM) cosmology. Especially at high redshift, we see increased rates of galaxy cluster and galaxy merging in LSS relative to the field, which is useful for studying the hierarchical merging predicted by LambdaCDM. The largest identified bound structures, superclusters, have not yet virialized. Despite the wide range of dynamical states of their constituent galaxies, groups, and clusters, they are all still actively evolving, providing an ideal laboratory in which to study cluster and galaxy evolution. In this dissertation, I present original research on several aspects of LSS and LambdaCDM cosmology. Three separate studies are included, each one focusing on a different aspect. In the first study, we use X-ray and optical observations from nine galaxy clusters at high redshift, some embedded in larger structures and some isolated, to study their evolutionary states. We extract X-ray gas temperatures and luminosities as well as optical velocity dispersions. These cluster properties are compared using low-redshift scaling relations. In addition, we employ several tests of substructure, using velocity histograms, Dressler-Shectman tests, and centroiding offsets. We conclude that two clusters out of our sample are most likely unrelaxed, and find support for deviations from self-similarity in the redshift evolution of the Lx-T relation. Our numerous complementary tests of the evolutionary state of clusters suggest potential under-estimations of systematic error in studies employing only a single such test. In the second study, we use multi-band imaging and spectroscopy to study active galactic nuclei (AGN) in high-redshift LSS. The AGN were identified using X-ray imaging and matched to optical catalogs that contained spectroscopic redshifts to identify members of the structures. AGN host galaxies tended to be associated with the

  17. Changing ionization conditions in SDSS galaxies with active galactic nuclei as a function of environment from pairs to clusters

    SciTech Connect

    Khabiboulline, Emil T.; Steinhardt, Charles L.; Silverman, John D.; Ellison, Sara L.; Mendel, J. Trevor; Patton, David R.

    2014-11-01

    We study how active galactic nucleus (AGN) activity changes across environments from galaxy pairs to clusters using 143,843 galaxies with z < 0.2 from the Sloan Digital Sky Survey. Using a refined technique, we apply a continuous measure of AGN activity, characteristic of the ionization state of the narrow-line emitting gas. Changes in key emission-line ratios ([N II] λ6548/Hα, [O III] λ5007/Hβ) between different samples allow us to disentangle different environmental effects while removing contamination. We confirm that galaxy interactions enhance AGN activity. However, conditions in the central regions of clusters are inhospitable for AGN activity even if galaxies are in pairs. These results can be explained through models of gas dynamics in which pair interactions stimulate the transfer of gas to the nucleus and clusters suppress gas availability for accretion onto the central black hole.

  18. Changing Ionization Conditions in SDSS Galaxies with Active Galactic Nuclei as a Function of Environment from Pairs to Clusters

    NASA Astrophysics Data System (ADS)

    Khabiboulline, Emil T.; Steinhardt, Charles L.; Silverman, John D.; Ellison, Sara L.; Mendel, J. Trevor; Patton, David R.

    2014-11-01

    We study how active galactic nucleus (AGN) activity changes across environments from galaxy pairs to clusters using 143,843 galaxies with z < 0.2 from the Sloan Digital Sky Survey. Using a refined technique, we apply a continuous measure of AGN activity, characteristic of the ionization state of the narrow-line emitting gas. Changes in key emission-line ratios ([N II] λ6548/Hα, [O III] λ5007/Hβ) between different samples allow us to disentangle different environmental effects while removing contamination. We confirm that galaxy interactions enhance AGN activity. However, conditions in the central regions of clusters are inhospitable for AGN activity even if galaxies are in pairs. These results can be explained through models of gas dynamics in which pair interactions stimulate the transfer of gas to the nucleus and clusters suppress gas availability for accretion onto the central black hole.

  19. Inhibition of nitrobenzene adsorption by water cluster formation at acidic oxygen functional groups on activated carbon.

    PubMed

    Kato, Yuichi; Machida, Motoi; Tatsumoto, Hideki

    2008-06-15

    The inhibition effect of nitrobenzene adsorption by water clusters formed at the acidic groups on activated carbon was examined in aqueous and n-hexane solution. The activated carbon was oxidized with nitric acid to introduce CO complexes and then outgassed in helium flow at 1273 K to remove them completely without changing the structural properties of the carbon as a reference adsorbent. The amounts of acidic functional groups were determined by applying Boehm titration. A relative humidity of 95% was used to adsorb water onto the carbon surface. Strong adsorption of water onto the oxidized carbon can be observed by thermogravimetric analysis. The adsorption kinetic rate was estimated to be controlled by diffusion from the kinetic analysis. Significant decline in both capacity and kinetic rate for nitrobenzene adsorption onto the oxidized carbon was also observed in n-hexane solution by preadsorption of water to the carbon surface, whereas it was not detected for the outgassed carbons. These results might reveal that water molecules forming clusters at the CO complexes inhibited the entrance of nitrobenzene into the interparticles of the carbon. PMID:18440013

  20. Microbial communication leading to the activation of silent fungal secondary metabolite gene clusters

    PubMed Central

    Netzker, Tina; Fischer, Juliane; Weber, Jakob; Mattern, Derek J.; König, Claudia C.; Valiante, Vito; Schroeckh, Volker; Brakhage, Axel A.

    2015-01-01

    Microorganisms form diverse multispecies communities in various ecosystems. The high abundance of fungal and bacterial species in these consortia results in specific communication between the microorganisms. A key role in this communication is played by secondary metabolites (SMs), which are also called natural products. Recently, it was shown that interspecies “talk” between microorganisms represents a physiological trigger to activate silent gene clusters leading to the formation of novel SMs by the involved species. This review focuses on mixed microbial cultivation, mainly between bacteria and fungi, with a special emphasis on the induced formation of fungal SMs in co-cultures. In addition, the role of chromatin remodeling in the induction is examined, and methodical perspectives for the analysis of natural products are presented. As an example for an intermicrobial interaction elucidated at the molecular level, we discuss the specific interaction between the filamentous fungi Aspergillus nidulans and Aspergillus fumigatus with the soil bacterium Streptomyces rapamycinicus, which provides an excellent model system to enlighten molecular concepts behind regulatory mechanisms and will pave the way to a novel avenue of drug discovery through targeted activation of silent SM gene clusters through co-cultivations of microorganisms. PMID:25941517

  1. Active-Space Coupled-Cluster Study of Electronic States of Be₃

    SciTech Connect

    Kowalski, Karol; Hirata, So; Wloch, M W.; Piecuch, Piotr; Windus, Theresa L.

    2005-08-15

    An automated implementation of the active-space coupled-cluster (CC) and equation-of-motion (EOM) CC methods with all singles and doubles, and triples defined via active orbitals (CCSDt, EOMCCSDt) employing Tensor Contraction Engine (TCE), is reported. The TCE-generated CCSDt/ codes are parallel and applicable to closed-and open-shell references. The effectiveness of the new code in describing electronic quasi-degeneracies is illustrated by the CCSDt / EOMCCSDt) calculations for the challenging Be₃system, which is characterized by a large number of low-lying excited states dominated by two-electron transitions and significant high order correlation effects in the ground electronic state. Different strategies for defining triple excitation s within the CCSDt / EOMCCSDt) approach are discussed.

  2. Application of space-time scan statistics to describe geographic and temporal clustering of visible drug activity.

    PubMed

    Linton, Sabriya L; Jennings, Jacky M; Latkin, Carl A; Gomez, Marisela B; Mehta, Shruti H

    2014-10-01

    Knowledge of the geographic and temporal clustering of drug activity can inform where health and social services are needed and can provide insight on the potential impact of local policies on drug activity. This ecologic study assessed the spatial and temporal distribution of drug activity in Baltimore, Maryland, prior to and following the implementation of a large urban redevelopment project in East Baltimore, which began in 2003. Drug activity was measured by narcotic calls for service at the neighborhood level. A space-time scan statistic approach was used to identify statistically significant clusters of narcotic calls for service across space and time, using a discrete Poisson model. After adjusting for economic deprivation and housing vacancy, clusters of narcotic calls for service were identified among neighborhoods located in Southeast, Northeast, Northwest, and West Baltimore from 2001 to 2010. Clusters of narcotic calls for service were identified among neighborhoods located in East Baltimore from 2001 to 2003, indicating a decrease in narcotic calls thereafter. A large proportion of clusters occurred among neighborhoods located in North and Northeast Baltimore after 2003, which indicated a potential spike during this time frame. These findings suggest potential displacement of drug activity coinciding with the initiation of urban redevelopment in East Baltimore. Space-time scan statistics should be used in future research to describe the potential implications of local policies on drug activity. PMID:25078036

  3. Clustering Home Activity Distributions for Automatic Detection of Mild Cognitive Impairment in Older Adults1

    PubMed Central

    Akl, Ahmad; Chikhaoui, Belkacem; Mattek, Nora; Kaye, Jeffrey; Austin, Daniel; Mihailidis, Alex

    2016-01-01

    The public health implications of growing numbers of older adults at risk for dementia places pressure on identifying dementia at its earliest stages so as to develop proactive management plans. The prodromal dementia phase commonly identified as mild cognitive impairment is an important target for this early detection of impending dementia amenable to treatment. In this paper, we propose a method for home-based automatic detection of mild cognitive impairment in older adults through continuous monitoring via unobtrusive sensing technologies. Our method is composed of two main stages: a training stage and a test stage. For training, room activity distributions are estimated for each subject using a time frame of ω weeks, and then affinity propagation is employed to cluster the activity distributions and to extract exemplars to represent the different emerging clusters. For testing, room activity distributions belonging to a test subject with unknown cognitive status are compared to the extracted exemplars and get assigned the labels of the exemplars that result in the smallest normalized Kullbak–Leibler divergence. The labels of the activity distributions are then used to determine the cognitive status of the test subject. Using the sensor and clinical data pertaining to 85 homes with single occupants, we were able to automatically detect mild cognitive impairment in older adults with an F0.5 score of 0.856. Also, we were able to detect the non-amnestic sub-type of mild cognitive impairment in older adults with an F0.5 score of 0.958.

  4. Nanoparticle cluster gas sensor: Pt activated SnO2 nanoparticles for NH3 detection with ultrahigh sensitivity.

    PubMed

    Liu, Xu; Chen, Nan; Han, Bingqian; Xiao, Xuechun; Chen, Gang; Djerdj, Igor; Wang, Yude

    2015-09-28

    Pt activated SnO2 nanoparticle clusters were synthesized by a simple solvothermal method. The structure, morphology, chemical state and specific surface area were analyzed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2-sorption studies, respectively. The SnO2 nanoparticle cluster matrix consists of tens of thousands of SnO2 nanoparticles with an ultra-small grain size estimated to be 3.0 nm. And there are abundant random-packed wormhole-like pores, caused by the inter-connection of the SnO2 nanoparticles, throughout each cluster. The platinum element is present in two forms including metal (Pt) and tetravalent metal oxide (PtO2) in the Pt activated SnO2 nanoparticle clusters. The as-synthesized pure and Pt activated SnO2 nanoparticle clusters were used to fabricate gas sensor devices. It was found that the gas response toward 500 ppm of ammonia was improved from 6.48 to 203.44 through the activation by Pt. And the results indicate that the sensor based on Pt activated SnO2 not only has ultrahigh sensitivity but also possesses good response-recovery properties, linear dependence, repeatability, selectivity and long-term stability, demonstrating the potential to use Pt activated SnO2 nanoparticle clusters as ammonia gas sensors. At the same time, the formation mechanisms of the unique nanoparticle clusters and highly enhanced sensitivity are also discussed. PMID:26289622

  5. On the luminosity of black hole cluster model of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Stoeger, W. R.; Pacholczyk, A. G.; Stepinski, T. F.

    1992-01-01

    The luminosity of a nuclear cluster of accreting black holes and other objects is discussed in terms of two accretion regimes: external supply of gas from outside the cluster and internal supply resulting from tidal disruption and capture of stars within the cluster. The external supply regime results in radiation being emitted from the innermost parts of the cluster while internal supply can efficiently feed the holes in the outer parts of the cluster as long as it is not too compact cluster and is embedded in a distribution of stars with a density larger than 10 exp 7 solar masses/cu pc.

  6. A multi-modal prostate segmentation scheme by combining spectral clustering and active shape models

    NASA Astrophysics Data System (ADS)

    Toth, Robert; Tiwari, Pallavi; Rosen, Mark; Kalyanpur, Arjun; Pungavkar, Sona; Madabhushi, Anant

    2008-03-01

    Segmentation of the prostate boundary on clinical images is useful in a large number of applications including calculating prostate volume during biopsy, tumor estimation, and treatment planning. Manual segmentation of the prostate boundary is, however, time consuming and subject to inter- and intra-reader variability. Magnetic Resonance (MR) imaging (MRI) and MR Spectroscopy (MRS) have recently emerged as promising modalities for detection of prostate cancer in vivo. In this paper we present a novel scheme for accurate and automated prostate segmentation on in vivo 1.5 Tesla multi-modal MRI studies. The segmentation algorithm comprises two steps: (1) A hierarchical unsupervised spectral clustering scheme using MRS data to isolate the region of interest (ROI) corresponding to the prostate, and (2) an Active Shape Model (ASM) segmentation scheme where the ASM is initialized within the ROI obtained in the previous step. The hierarchical MRS clustering scheme in step 1 identifies spectra corresponding to locations within the prostate in an iterative fashion by discriminating between potential prostate and non-prostate spectra in a lower dimensional embedding space. The spatial locations of the prostate spectra so identified are used as the initial ROI for the ASM. The ASM is trained by identifying user-selected landmarks on the prostate boundary on T2 MRI images. Boundary points on the prostate are identified using mutual information (MI) as opposed to the traditional Mahalanobis distance, and the trained ASM is deformed to fit the boundary points so identified. Cross validation on 150 prostate MRI slices yields an average segmentation sensitivity, specificity, overlap, and positive predictive value of 89, 86, 83, and 93% respectively. We demonstrate that the accurate initialization of the ASM via the spectral clustering scheme is necessary for automated boundary extraction. Our method is fully automated, robust to system parameters, and computationally efficient.

  7. Modeling active galactic nucleus feedback in cool-core clusters: The balance between heating and cooling

    SciTech Connect

    Li, Yuan; Bryan, Greg L.

    2014-07-01

    We study the long-term evolution of an idealized cool-core galaxy cluster under the influence of momentum-driven active galactic nucleus (AGN) feedback using three-dimensional high-resolution (60 pc) adaptive mesh refinement simulations. The feedback is modeled with a pair of precessing jets whose power is calculated based on the accretion rate of the cold gas surrounding the supermassive black hole (SMBH). The intracluster medium first cools into clumps along the propagation direction of the jets. As the jet power increases, gas condensation occurs isotropically, forming spatially extended structures that resemble the observed Hα filaments in Perseus and many other cool-core clusters. Jet heating elevates the gas entropy, halting clump formation. The cold gas that is not accreted onto the SMBH settles into a rotating disk of ∼10{sup 11} M {sub ☉}. The hot gas cools directly onto the disk while the SMBH accretes from its innermost region, powering the AGN that maintains a thermally balanced state for a few Gyr. The mass cooling rate averaged over 7 Gyr is ∼30 M {sub ☉} yr{sup –1}, an order of magnitude lower than the classic cooling flow value. Medium resolution simulations produce similar results, while in low resolution runs, the cluster experiences cycles of gas condensation and AGN outbursts. Owing to its self-regulating mechanism, AGN feedback can successfully balance cooling with a wide range of model parameters. Our model also produces cold structures in early stages that are in good agreement with the observations. However, the long-lived massive cold disk is unrealistic, suggesting that additional physical processes are still needed.

  8. The angular clustering of WISE-selected active galactic nuclei: Different halos for obscured and unobscured active galactic nuclei

    SciTech Connect

    Donoso, E.; Yan, Lin; Stern, D.; Assef, R. J.

    2014-07-01

    We calculate the angular correlation function for a sample of ∼170,000 active galactic nuclei (AGNs) extracted from the Wide-field Infrared Survey Explorer (WISE) catalog, selected to have red mid-IR colors (W1 – W2 > 0.8) and 4.6 μm flux densities brighter than 0.14 mJy). The sample is expected to be >90% reliable at identifying AGNs and to have a mean redshift of (z) = 1.1. In total, the angular clustering of WISE AGNs is roughly similar to that of optical AGNs. We cross-match these objects with the photometric Sloan Digital Sky Survey catalog and distinguish obscured sources with r – W2 > 6 from bluer, unobscured AGNs. Obscured sources present a higher clustering signal than unobscured sources. Since the host galaxy morphologies of obscured AGNs are not typical red sequence elliptical galaxies and show disks in many cases, it is unlikely that the increased clustering strength of the obscured population is driven by a host galaxy segregation bias. By using relatively complete redshift distributions from the COSMOS survey, we find that obscured sources at (z) ∼ 0.9 have a bias of b = 2.9 ± 0.6 and are hosted in dark matter halos with a typical mass of log (M/M {sub ☉} h {sup –1}) ∼ 13.5. In contrast, unobscured AGNs at (z) ∼ 1.1 have a bias of b = 1.6 ± 0.6 and inhabit halos of log (M/M {sub ☉} h {sup –1}) ∼ 12.4. These findings suggest that obscured AGNs inhabit denser environments than unobscured AGNs, and they are difficult to reconcile with the simplest AGN unification models, where obscuration is driven solely by orientation.

  9. Testing a workplace physical activity intervention: a cluster randomized controlled trial

    PubMed Central

    2011-01-01

    Background Increased physical activity levels benefit both an individuals' health and productivity at work. The purpose of the current study was to explore the impact and cost-effectiveness of a workplace physical activity intervention designed to increase physical activity levels. Methods A total of 1260 participants from 44 UK worksites (based within 5 organizations) were recruited to a cluster randomized controlled trial with worksites randomly allocated to an intervention or control condition. Measurement of physical activity and other variables occurred at baseline, and at 0 months, 3 months and 9 months post-intervention. Health outcomes were measured during a 30 minute health check conducted in worksites at baseline and 9 months post intervention. The intervention consisted of a 3 month tool-kit of activities targeting components of the Theory of Planned Behavior, delivered in-house by nominated facilitators. Self-reported physical activity (measured using the IPAQ short-form) and health outcomes were assessed. Results and discussion Multilevel modelling found no significant effect of the intervention on MET minutes of activity (from the IPAQ) at any of the follow-up time points controlling for baseline activity. However, the intervention did significantly reduce systolic blood pressure (B = -1.79 mm/Hg) and resting heart rate (B = -2.08 beats) and significantly increased body mass index (B = .18 units) compared to control. The intervention was found not to be cost-effective, however the substantial variability round this estimate suggested that further research is warranted. Conclusions The current study found mixed support for this worksite physical activity intervention. The paper discusses some of the tensions involved in conducting rigorous evaluations of large-scale randomized controlled trials in real-world settings. Trial registration Current controlled trials ISRCTN08807396 PMID:21481265

  10. Medical Education and Communication Companies Involved in CME: An Updated Profile

    ERIC Educational Resources Information Center

    Peterson, Eric D.; Overstreet, Karen M.; Parochka, Jacqueline N.; Lemon, Michael R.

    2008-01-01

    Introduction: Medical Education and Communication Companies (MECCs) represent approximately 21% of the providers accredited by the Accreditation Council for Continuing Medical Education (ACCME), yet relatively little is known about these organizations in the greater continuing medical education (CME) community. Two prior studies described them,…

  11. Radio imaging of synchrotron emission associated with a CME on the 14th of August 2010

    NASA Astrophysics Data System (ADS)

    Bain, H. M.; Krucker, S.; Raftery, C. L.; Saint-Hilaire, P.

    2012-12-01

    Radio observations can be used to identify sources of electron acceleration within flares and CMEs. In a small number of events, radio imaging has revealed the presence of synchrotron emission from nonthermal electrons in the expanding loops of the CME (Bastian et al. (2001), Maia et al. (2007) and Démoulin et al. (2012)). Events in which the synchrotron emission is sufficiently bright to be identified in the presence of plasma emission from radio bursts, which are prevalent at meter wavelengths, are infrequent. Using radio images from the Nançay Radioheliograph (NRH) we present observations of synchrotron emission associated with a CME which occurred on the 14th of August 2010. Using context observations from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory, the SWAP instrument onboard Proba2, the LASCO coronograph onboard SOHO and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), we follow the propagation of the CME out to 2-3 solar radii and characterize the associated electron distribution. We find that the synchrotron emission is cospatial with the CME core.

  12. Analysis of Metric Type II Burst and EUV Waves Generated by Shock Wave Driven by Cme

    NASA Astrophysics Data System (ADS)

    Cunha-Silva, Rafael; Fernandes, Francisco; Selhorst, Caius

    2016-07-01

    The relationship between solar type II radio bursts produced by plasma oscillations and coronal shocks is well shown since the 1960s. However, the details of the association between the drivers of the shocks and the metric type II bursts remains a controversial issue. The flares and the coronal mass ejections (CMEs) are the potential drivers of these shocks. In this work, we present the analysis of a metric type II burst observed on May 17, 2013, by spectrometers from e-CALLISTO network and EUV images from the Extreme Ultraviolet Imager (EUVI), aboard the STEREO. The event was associated with an M3.2 X-ray flare and a halo CME. The EUV images show the EUV wave was produced by the expansion of the CME. The heights of the EUV wave fronts and the magnetic field intensity determined in the regions of the shock are consistent with those the heights of radio source obtained with the three-fold Newkirk density model, which suggests an oblique propagation of the shock. The finding of an accelerating shock with speed of 530-640 km/s and of 870-1220 km/s for the first and the second stages of the type II emission, respectively, is consistent with both the average speed of the associated EUV wave front, of 626 km/s, during the initial expansion of the CME, and with the linear speed of the CME, of 1345 km/s. These results will be presented and discussed.

  13. The Integrated Joslin Performance Improvement/CME Program: A New Paradigm for Better Diabetes Care

    ERIC Educational Resources Information Center

    Brown, Julie A.; Beaser, Richard S.; Neighbours, James; Shuman, Jill

    2011-01-01

    Ongoing continuing medical education is an essential component of life-long learning and can have a positive influence on patient outcomes. However, some evidence suggests that continuing medical education has not fulfilled its potential as a performance improvement (PI) tool, in part due to a paradigm of CME that has focused on the quantity of…

  14. Evidence of a blast shock wave formation in a "CME-streamer" interaction

    NASA Astrophysics Data System (ADS)

    Eselevich, V. G.; Eselevich, M. V.; Sadykov, V. M.; Zimovets, I. V.

    2015-12-01

    Analysis of the solar event on 16 February 2011 (SOL2011-02-16T14:19) allows to classify it as an "impulsive" coronal mass ejection (CME) event. It is argued that the observed deviation of a streamer ray from its pre-event state and generation of a metric type II radio burst in this event was a result of a "CME-streamer" interaction in the lower corona (r≲ 1.5R⊙). Most probably, it was a consequence of an impulsive action of a compressed magnetic field to the streamer. This compression of the coronal magnetic field was due to a moving and expanding magnetic flux rope, which was a core of the CME. The estimated radial speed of the type II burst sources was significantly (≈2-;8 times) larger than the radial speed of the erupting flux rope, and it decreased rapidly with time. This indicates that during the "CME-streamer" interaction a blast shock wave could be excited and propagated along the streamer.

  15. Are CME 'interactions' Really Important for Accelerating Major Solar Energetic Particle Events?

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Lawrence, G. R.; Haggerty, D. K.; Kucera, T.; Szabo, A.

    2002-01-01

    Recent studies have proposed that the presence or absence of an interaction with a preceding coronal mass ejection (CME) or other coronal structure within approximately 50R(sub s), of the Sun discriminates large, fast CMEs associated with major solar energetic particle (SEP) events from those that are not. We conclude that there is no compelling evidence that, if such interactions take place, they play an important role in SEP acceleration. Reasons include: The reported statistical results are consistent with a chance association between interacting CMEs and SEP events; Energetic SEPs are detected at Earth typically before or around the time when the primary CME enters the LASCO C2 field of view - interactions higher in the corona cannot play a role in acceleration of these particles; For approximately 60% of major SEP events in 1997-2001, the preceding CME fades into the background corona or is relatively narrow (less than 40 deg), suggesting any interaction will be weak; Radio signatures attributed to CME interaction occur after SEP acceleration has commenced.

  16. Organizational Change in Management of Hepatitis C: Evaluation of a CME Program

    ERIC Educational Resources Information Center

    Garrard, Judith; Choudary, Veena; Groom, Holly; Dieperink, Eric; Willenbring, Mark L.; Durfee, Janet M.; Ho, Samuel B.

    2006-01-01

    Introduction: Effective treatment regimens exist for the hepatitis C virus (HCV); however, clinicians are often resistant to evaluation or treatment of patients with alcohol or substance abuse problems. We describe a continuing medical education (CME) program for clinicians in a nationwide health care system, with emphasis on current treatment…

  17. Reconciling CME Kinematics using Radio and White-light Observations from STEREO and SOHO

    NASA Astrophysics Data System (ADS)

    Gopalswamy, Nat; Yashiro, Seiji; Xie, Hong; Makela, Pertti; Akiyama, Sachiko; Reiner, Michael; MacDowall, Robert

    2014-05-01

    We study the characteristics of nonthermal radio emission associated with coronal mass ejections (CMEs) observed by STEREO, SOHO, and Wind spacecraft. In particular, we examine three backside CMEs associated with type II radio bursts at frequencies below 16 MHz. These bursts are known to be excellent indicators of solar energetic particle events. We use the universal drift rate spectrum of type II radio bursts and the inferred density scale heights in the corona and interplanetary medium o estimate the speed of the shock waves that produce the type II radio bursts. We find that the radio bursts can provide an accurate estimate of the CME speeds. We consider three backside events and a cannibalism event to show the usefulness of radio dynamic spectrum in inferring CME kinematics. We use radio direction finding technique to show that CME-CME interaction results in enhanced nonthermal radio emission. The radio data also provide constraints on the particle acceleration mechanisms and the reason for the energetic particles observed at wide-ranging longitudes. Finally we infer the shape and extent of the shock associated with one of the biggest solar energetic particle events in the space era.

  18. A CME-driven solar wind distrubance observed at both low and high heliographic latitudes

    SciTech Connect

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

    1995-07-01

    A solar wind disturbance produced by a fast coronal mass ejection, CME, that departed from the Sun on Feburary 20, 1994 was observed in the ecliptic plane at 1 AU by IMP 8 and at high heliographic latitudes at 3.53 AU by Ulysses. In the ecliptic the disturbance included a strong forward shock but no reverse shock, while at high latitudes the disturbance was bounded by a relatively weak forward-reverse shock pair. It is clear that the disturbance in the ecliptic plane was driven primarily by the relative speed between the CME and a slower ambient solar wind ahead, whereas at higher latitudes the disturbance was driven by expansion of the CME. The combined IMP 8 and Ulysses observations thus provide a graphic illustration of how a single fast CME can produce very different types of solar wind disturbances at low and high heliographic latitudes. Simple numerical simulations help explain observed differences at the two spacecraft. 12 refs., 3 figs.

  19. Constraints on CME Evolution from in situ Observations of Ionic Charge States

    NASA Technical Reports Server (NTRS)

    Gruesbeck, Jacob R.; Lepri, Susan T.; Zurbuchen, Thomas H.; Antiochos, Spiro K.

    2010-01-01

    We present a novel procedure for deriving the physical properties of Coronal Mass Ejections (CMES) in the corona. Our methodology uses in-situ measurements of ionic charge states of C, O, Si and Fe in the heliosphere and interprets them in the context of a model for the early evolution of ICME plasma, between 2 - 5 R-solar. We find that the data can be fit only by an evolution that consists of an initial heating of the plasma, followed by an expansion that ultimately results in cooling. The heating profile is consistent with a compression of coronal plasma due to flare reconnect ion jets and an expansion cooling due to the ejection, as expected from the standard CME/flare model. The observed frozen-in ionic charge states reflect this time-history and, therefore, provide important constraints for the heating and expansion time-scales, as well as the maximum temperature the CME plasma is heated to during its eruption. Furthermore, our analysis places severe limits on the possible density of CME plasma in the corona. We discuss the implications of our results for CME models and for future analysis of ICME plasma composition.

  20. Solar Wind Electron Strahls Associated with a High-Latitude CME: Ulysses Observations

    NASA Astrophysics Data System (ADS)

    Lazar, M.; Pomoell, J.; Poedts, S.; Dumitrache, C.; Popescu, N. A.

    2014-11-01

    Counterstreaming beams of electrons are ubiquitous in coronal mass ejections (CMEs) - although their existence is not unanimously accepted as a necessary and/or sufficient signature of these events. We continue the investigation of a high-latitude CME registered by the Ulysses spacecraft on 18 - 19 January 2002 (Dumitrache, Popescu, and Oncica, Solar Phys. 272, 137, 2011), by surveying the solar-wind electron distributions associated with this event. The temporal evolution of the pitch-angle distributions reveals populations of electrons that are distinguishable through their anisotropy, with clear signatures of i) electron strahls, ii) counter-streaming in the magnetic clouds and their precursors, and iii) unidirectionality in the fast wind preceding the CME. The analysis of the counter-streams inside the CME allows us to elucidate the complexity of the magnetic-cloud structures embedded in the CME and to refine the borders of the event. Identifying such strahls in CMEs, which preserve properties of the low β [<1] coronal plasma, gives more support to the hypothesis that these populations are remnants of the hot coronal electrons that escape from the electrostatic potential of the Sun into the heliosphere.

  1. A conserved activation cluster is required for allosteric communication in HtrA-family proteases.

    PubMed

    de Regt, Anna K; Kim, Seokhee; Sohn, Jungsan; Grant, Robert A; Baker, Tania A; Sauer, Robert T

    2015-03-01

    In E. coli, outer-membrane stress causes a transcriptional response through a signaling cascade initiated by DegS cleavage of a transmembrane antisigma factor. Each subunit of DegS, an HtrA-family protease, contains a protease domain and a PDZ domain. The trimeric protease domain is autoinhibited by the unliganded PDZ domains. Allosteric activation requires binding of unassembled outer-membrane proteins (OMPs) to the PDZ domains and protein substrate binding. Here, we identify a set of DegS residues that cluster together at subunit-subunit interfaces in the trimer, link the active sites and substrate binding sites, and are crucial for stabilizing the active enzyme conformation in response to OMP signaling. These residues are conserved across the HtrA-protease family, including orthologs linked to human disease, supporting a common mechanism of allosteric activation. Indeed, mutation of residues at homologous positions in the DegP quality-control protease also eliminates allosteric activation. PMID:25703375

  2. Eastern region represents a worrying cluster of active hepatitis C in Algeria in 2012.

    PubMed

    Bensalem, Aïcha; Selmani, Karima; Hihi, Narjes; Bencherifa, Nesrine; Mostefaoui, Fatma; Kerioui, Cherif; Pineau, Pascal; Debzi, Nabil; Berkane, Saadi

    2016-08-01

    Algeria is the largest country of Africa, peopled with populations living a range of traditional/rural and modern/urban lifestyles. The variations of prevalence of chronic active hepatitis care poorly known on the Algerian territory. We conducted a retrospective survey on all patients (n = 998) referred to our institution in 2012 and confirmed by us for an active hepatitis C. Half of the hepatitis C virus (HCV) isolates were genotyped. Forty Algerian regions out of the 48 were represented in our study. Three geographical clusters (Aïn-Temouchent/SidiBelAbbes, Algiers, and a large Eastern region) with an excess of active hepatitis C were observed. Patients coming from the Eastern cluster (Batna, Khenchela, Oum el Bouaghi, and Tebessa) were strongly over-represented (49% of cases, OR = 14.5, P < 0.0001). The hallmarks of Eastern region were an excess of women (65% vs. 46% in the remaining population, P < 0.0001) and the almost exclusive presence of HCV genotype 1 (93% vs. 63%, P = 0.0001). The core of the epidemics was apparently located in Khenchela (odds ratio = 24.6, P < 0.0001). This situation is plausibly connected with nosocomial transmission or traditional practices as scarification (Hijama), piercing or tattooing, very lively in this region. Distinct hepatitis C epidemics are currently affecting Algerian population. The most worrying situation is observed in rural regions located east of Algeria. J. Med. Virol. 88:1394-1403, 2016. © 2016 Wiley Periodicals, Inc. PMID:26856380

  3. THE CLUSTERING OF GALAXIES AROUND RADIO-LOUD ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Worpel, Hauke; Brown, Michael J. I.; Jones, D. Heath; Floyd, David J. E.; Beutler, Florian

    2013-07-20

    We examine the hypothesis that mergers and close encounters between galaxies can fuel active galactic nuclei (AGNs) by increasing the rate at which gas accretes toward the central black hole. We compare the clustering of galaxies around radio-loud AGNs with the clustering around a population of radio-quiet galaxies with similar masses, colors, and luminosities. Our catalog contains 2178 elliptical radio galaxies with flux densities greater than 2.8 mJy at 1.4 GHz from the Six Degree Field Galaxy Survey. We find tentative evidence that radio AGNs with more than 200 times the median radio power have, on average, more close (r < 160 kpc) companions than their radio-quiet counterparts, suggesting that mergers play a role in forming the most powerful radio galaxies. For ellipticals of fixed stellar mass, the radio power is neither a function of large-scale environment nor halo mass, consistent with the radio powers of ellipticals varying by orders of magnitude over billions of years.

  4. Using Targeted Active-Learning Exercises and Diagnostic Question Clusters to Improve Students' Understanding of Carbon Cycling in Ecosystems

    ERIC Educational Resources Information Center

    Maskiewicz, April Cordero; Griscom, Heather Peckham; Welch, Nicole Turrill

    2012-01-01

    In this study, we used targeted active-learning activities to help students improve their ways of reasoning about carbon flow in ecosystems. The results of a validated ecology conceptual inventory (diagnostic question clusters [DQCs]) provided us with information about students' understanding of and reasoning about transformation of inorganic and…

  5. Differences between CME associated and CH associated RED events during 2005

    NASA Astrophysics Data System (ADS)

    Alyana, Radharani; Rajaram, Girija; Rathod, Jatin; Chandrasekhar Reddy, A.; Misra, D. S.; Patil, C. G.; Prasad, M. Y. S.

    2007-12-01

    As part of study of RED (Relativistic Electron Dropout) events at Geostationary orbit, we have classified them on the basis of their solar causes. We find that the solar causes associated with RED events are Interplanetary (IP) Shocks, Coronal Mass Ejection (CME), Flares, Magnetic Clouds and Corotating Interaction Regions (CIR) followed by Coronal Hole (CH) stream. Here we have taken CME and CH associated RED events during 2005. We have studied Interplanetary parameters (IP) (i.e. solar wind Velocity (Vsw), solar wind Ion density (Nsw), solar wind dynamic pressure (P_sw), total Interplanetary magnetic field B along with its north-south component, Bz), Radiation belt (RB) parameters at geostationary orbit (i.e. electron flux >2 MeV, Hp component (i.e. the component of magnetic field parallel to the spin axis of the satellite) and dayside magnetopause distance (MP)) and the geomagnetic indices (i.e. Dst and Kp) and Cosmic Ray Neutron Monitor (CRNM) count. The parameters which show significant differences between CME and CH events are Vsw, Psw, B, Bz, Dst and Kp, with Vsw and Dst showing the largest differences. As typical examples, in the case of the CME of 22 January, 2005, Vsw touches over 975 km s^{-1} and Dst is Sudden Storm Commencement (SSC) type with minimum Dst being -110 nT . In the case of the CH of 05 April, Vsw is only 650 km s^{-1} and Dst is of Gradual Commencement (GC) type with minimum Dst of -80 nT. In this paper we present differences observed in the above mentioned parameters for several RED events associated with CME and CH during 2005.

  6. Differences Between CME Associated and CH Associated RED Events During 2005 (P4)

    NASA Astrophysics Data System (ADS)

    Alyana, R.; et al.

    2006-11-01

    As Part of study of RED (Relativistic Electron Decrease) events at Geostationary orbit, we have classified them on the basis of their solar cause. We find that the solar causes associated with RED events (J.J.Lee et.al., 2006) are Interplanetary Shocks (IPS), Coronal Mass Ejection (CME), Coronal Hole (CH), Flares, Magnetic Clouds and Corotating Interaction Regions (CIR). For present, we have taken CME and CH associated RED events during 2005. We study Interplanetary parameters (i.e. solar wind Velocity (Vsw), solar wind Ion density (Nsw), solar wind dynamic pressure (Pdsw), total Interplanetary magnetic field B along with its north-south component, Bz), Radiation belt parameters at geostationary orbit (i.e. electron flux>2Mev, Hp component (i.e. the component of magnetic field parallel to the spin axis of the satellite) and dayside magnetopause distance (MP)) and the geomagnetic indices (i.e. Dst, Kp and CRNM count). The parameters which show significant differences between CME and CH events are Vsw, Psw, B, Bz, Dst and Kp, with Vsw and Dstc showing the largest differences. As typical examples, in the case of the CME of 22nd January, 2005, Vsw touches over 975 km/sec and Dst is Sudden Storm Commencement (SSC) type with minimum Dst being 110 nT. In the case of the CH of 5th April, Vsw is only 650 km/sec and Dst is of Gradual Commencement (GC) type with minimum Dst of -80 nT. In this paper we present differences observed in the above mentioned parameters for several RED events associated with CME and CH during 2005.

  7. NanoCluster Beacons as reporter probes in rolling circle enhanced enzyme activity detection

    NASA Astrophysics Data System (ADS)

    Juul, Sissel; Obliosca, Judy M.; Liu, Cong; Liu, Yen-Liang; Chen, Yu-An; Imphean, Darren M.; Knudsen, Birgitta R.; Ho, Yi-Ping; Leong, Kam W.; Yeh, Hsin-Chih

    2015-04-01

    As a newly developed assay for the detection of endogenous enzyme activity at the single-catalytic-event level, Rolling Circle Enhanced Enzyme Activity Detection (REEAD) has been used to measure enzyme activity in both single human cells and malaria-causing parasites, Plasmodium sp. Current REEAD assays rely on organic dye-tagged linear DNA probes to report the rolling circle amplification products (RCPs), the cost of which may hinder the widespread use of REEAD. Here we show that a new class of activatable probes, NanoCluster Beacons (NCBs), can simplify the REEAD assays. Easily prepared without any need for purification and capable of large fluorescence enhancement upon hybridization, NCBs are cost-effective and sensitive. Compared to conventional fluorescent probes, NCBs are also more photostable. As demonstrated in reporting the human topoisomerases I (hTopI) cleavage-ligation reaction, the proposed NCBs suggest a read-out format attractive for future REEAD-based diagnostics.As a newly developed assay for the detection of endogenous enzyme activity at the single-catalytic-event level, Rolling Circle Enhanced Enzyme Activity Detection (REEAD) has been used to measure enzyme activity in both single human cells and malaria-causing parasites, Plasmodium sp. Current REEAD assays rely on organic dye-tagged linear DNA probes to report the rolling circle amplification products (RCPs), the cost of which may hinder the widespread use of REEAD. Here we show that a new class of activatable probes, NanoCluster Beacons (NCBs), can simplify the REEAD assays. Easily prepared without any need for purification and capable of large fluorescence enhancement upon hybridization, NCBs are cost-effective and sensitive. Compared to conventional fluorescent probes, NCBs are also more photostable. As demonstrated in reporting the human topoisomerases I (hTopI) cleavage-ligation reaction, the proposed NCBs suggest a read-out format attractive for future REEAD-based diagnostics. Electronic

  8. Dynamics of fractal cluster colloidal gels with embedded active Janus particles

    NASA Astrophysics Data System (ADS)

    Solomon, Michael; Szakasits, Megan; Zhang, Wenxuan

    We find that fractal cluster gels of colloids in which platinum-coated Janus particles have been embedded exhibit enhanced mobility when the Janus particles are made active by the addition of hydrogen peroxide. Gelation is induced through addition of a divalent salt, magnesium chloride, to an initially stable suspension of Janus and polystyrene colloids, each of size about 1 micron. After the gels have been created, the embedded Janus colloids are activated by hydrogen peroxide, which is delivered to the system through a porous hydrogel membrane. We vary the ratio of active to passive colloids in the gels from about 1:20 to 1:8. Changes in structure and dynamics are visualized by two channel confocal laser scanning microscopy. By image analysis, we determine the particle positions and compute the mean squared displacement (MSD) of all particles in the gel. We measure the mobility enhancement in the fractal gels as a function of hydrogen peroxide concentration and Janus particle concentration and discuss the results in terms of the force provided by each active particle to the fractal gel network.

  9. Graphdiyne oxides as excellent substrate for electroless deposition of Pd clusters with high catalytic activity.

    PubMed

    Qi, Hetong; Yu, Ping; Wang, Yuexiang; Han, Guangchao; Liu, Huibiao; Yi, Yuanping; Li, Yuliang; Mao, Lanqun

    2015-04-29

    Graphdiyne (GDY), a novel kind of two-dimensional carbon allotrope consisting of sp- and sp(2)-hybridized carbon atoms, is found to be able to serve as the reducing agent and stabilizer for electroless deposition of highly dispersed Pd nanoparticles owing to its low reduction potential and highly conjugated electronic structure. Furthermore, we observe that graphdiyne oxide (GDYO), the oxidation form of GDY, can be used as an even excellent substrate for electroless deposition of ultrafine Pd clusters to form Pd/GDYO nanocomposite that exhibits a high catalytic performance toward the reduction of 4-nitrophenol. The high catalytic performance is considered to benefit from the rational design and electroless deposition of active metal catalysts with GDYO as the support. PMID:25871853

  10. The role of geometrical symmetry on thermally activated processes in clusters of interacting dipolar moments

    NASA Astrophysics Data System (ADS)

    Hovorka, Ondrej; Barker, Joe; Friedman, Gary; Chantrell, Roy

    2014-03-01

    Thermally activated magnetization decay is studied in ensembles of clusters of interacting dipolar moments by applying the master-equation formalism, as a model of thermal relaxation in systems of interacting single-domain ferromagnetic nanoparticles. Solving the associated master-equation reveals a breakdown of the energy barrier picture depending on the geometrical symmetry of structures. Deviations are most pronounced for reduced symmetry and result in a strong interaction dependence of relaxation rates on the memory of initialization of an ensemble. Developed is a simple two-state system description of an ensemble, which accounts for the observed anomalies. These results follow from a semi-analytical treatment, and are fully supported by kinetic Monte-Carlo simulations. OH gratefully acknowledges support from a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme under grant agreement PIEF-GA-2010-273014.

  11. N2O reduction by the mu4-sulfide-bridged tetranuclear CuZ cluster active site.

    PubMed

    Chen, Peng; Gorelsky, Serge I; Ghosh, Somdatta; Solomon, Edward I

    2004-08-13

    Nitrous oxide (N2O) reduction is a chemical challenge both in the selective oxidation of organic substrates by N2O and in the removal of N2O as a green-house gas. The reduction of N2O is thermodynamically favorable but kinetically inert, and requires activating transition-metal centers. In biological systems, N2O reduction is the last step in the denitrification process of the bacterial nitrogen cycle and is accomplished by the enzyme nitrous oxide reductase, whose active site consists of a micro4-sulfide-bridged tetranuclear CuZ cluster which has many unusual spectroscopic features. Recent studies have developed a detailed electronic-structure description of the resting CuZ cluster, determined its catalytically relevant state, and provided insight into the role of this tetranuclear copper cluster in N2O activation and reduction. PMID:15307074

  12. Tuning of silver cluster emission from blue to red using a bio-active peptide in water.

    PubMed

    Roy, Subhasish; Baral, Abhishek; Banerjee, Arindam

    2014-03-26

    Blue, green, and red emitting silver quantum clusters have been prepared through green chemical approach by using a bio-active peptide glutathione (reduced) in a 50 mM phosphate buffer at pH 7.46. This study describes fluorescence emission tuning of the silver clusters by making different sized Ag clusters using slightly different reaction conditions keeping the same stabilizing ligand, reducing agent, solvent system, and silver salt precursor. The preparation procedure of these silver quantum clusters is new and highly reproducible. Each of these clusters shows very interesting fluorescence properties with large stokes shifts, and the quantum yields of blue, green, and red clusters are 2.08%, 0.125%, and 1.39%, respectively. These silver quantum clusters have been characterized by using different techniques including fluorescence spectroscopy, UV-vis spectroscopy, field-emission gun transmission electron microscopic (FEG-TEM) imaging and MALDI-TOF MS analyses. MALDI-TOF MS analyses show that the size of these blue, green and red emitting silver clusters are Ag5 (NC1, nanoclusters 1), Ag8 (NC2, nanoclusters 2) and Ag13 (NC3, nanoclusters 3), respectively, by using 2,5-dihydroxybenzoic acid as a matrix. These clusters are stable in broad ranges of pH. The NC3 (red emitting) has been successfully utilized for selective and sensitive detection of toxic Hg(II) ions in water by using even naked eyes, fluorometric, and calorimetric studies. The lower limit of detection of Hg(II) ions in water has been estimated to be 126 and 245 nM from fluorometric and UV-vis analyses, respectively. Enthalpy change (ΔH) during this Hg(II) sensing process is 2508 KJ mol(-1). PMID:24568193

  13. The Sound of Silence: Activating Silent Biosynthetic Gene Clusters in Marine Microorganisms.

    PubMed

    Reen, F Jerry; Romano, Stefano; Dobson, Alan D W; O'Gara, Fergal

    2015-08-01

    Unlocking the rich harvest of marine microbial ecosystems has the potential to both safeguard the existence of our species for the future, while also presenting significant lifestyle benefits for commercial gain. However, while significant advances have been made in the field of marine biodiscovery, leading to the introduction of new classes of therapeutics for clinical medicine, cosmetics and industrial products, much of what this natural ecosystem has to offer is locked in, and essentially hidden from our screening methods. Releasing this silent potential represents a significant technological challenge, the key to which is a comprehensive understanding of what controls these systems. Heterologous expression systems have been successful in awakening a number of these cryptic marine biosynthetic gene clusters (BGCs). However, this approach is limited by the typically large size of the encoding sequences. More recently, focus has shifted to the regulatory proteins associated with each BGC, many of which are signal responsive raising the possibility of exogenous activation. Abundant among these are the LysR-type family of transcriptional regulators, which are known to control production of microbial aromatic systems. Although the environmental signals that activate these regulatory systems remain unknown, it offers the exciting possibility of evoking mimic molecules and synthetic expression systems to drive production of potentially novel natural products in microorganisms. Success in this field has the potential to provide a quantum leap forward in medical and industrial bio-product development. To achieve these new endpoints, it is clear that the integrated efforts of bioinformaticians and natural product chemists will be required as we strive to uncover new and potentially unique structures from silent or cryptic marine gene clusters. PMID:26264003

  14. The Sound of Silence: Activating Silent Biosynthetic Gene Clusters in Marine Microorganisms

    PubMed Central

    Reen, F. Jerry; Romano, Stefano; Dobson, Alan D.W.; O’Gara, Fergal

    2015-01-01

    Unlocking the rich harvest of marine microbial ecosystems has the potential to both safeguard the existence of our species for the future, while also presenting significant lifestyle benefits for commercial gain. However, while significant advances have been made in the field of marine biodiscovery, leading to the introduction of new classes of therapeutics for clinical medicine, cosmetics and industrial products, much of what this natural ecosystem has to offer is locked in, and essentially hidden from our screening methods. Releasing this silent potential represents a significant technological challenge, the key to which is a comprehensive understanding of what controls these systems. Heterologous expression systems have been successful in awakening a number of these cryptic marine biosynthetic gene clusters (BGCs). However, this approach is limited by the typically large size of the encoding sequences. More recently, focus has shifted to the regulatory proteins associated with each BGC, many of which are signal responsive raising the possibility of exogenous activation. Abundant among these are the LysR-type family of transcriptional regulators, which are known to control production of microbial aromatic systems. Although the environmental signals that activate these regulatory systems remain unknown, it offers the exciting possibility of evoking mimic molecules and synthetic expression systems to drive production of potentially novel natural products in microorganisms. Success in this field has the potential to provide a quantum leap forward in medical and industrial bio-product development. To achieve these new endpoints, it is clear that the integrated efforts of bioinformaticians and natural product chemists will be required as we strive to uncover new and potentially unique structures from silent or cryptic marine gene clusters. PMID:26264003

  15. Temporal Offsets Between Maximum CME Speed Index and Solar, Geomagnetic, and Interplanetary Indicators During Solar Cycle 23 and the Ascending Phase of Cycle 24

    NASA Astrophysics Data System (ADS)

    Özgüç, A.; Kilcik, A.; Georgieva, K.; Kirov, B.

    2016-05-01

    On the basis of a morphological analysis of yearly values of the maximum coronal mass ejection (CME) speed index, the sunspot number and total sunspot area, sunspot magnetic field, and solar flare index, the solar wind speed and interplanetary magnetic field strength, and the geomagnetic Ap and D_{st} indices, we point out the particularities of solar and geomagnetic activity during the last Cycle 23, the long minimum that followed it, and the ascending branch of Cycle 24. We also analyze the temporal offset between the maximum CME speed index and the above-mentioned solar, geomagnetic, and interplanetary indices. It is found that this solar activity index, analyzed jointly with other solar activity, interplanetary parameters, and geomagnetic activity indices, shows a hysteresis phenomenon. It is observed that these parameters follow different paths for the ascending and descending phases of Cycle 23. The hysteresis phenomenon represents a clue in the search for physical processes responsible for linking the solar activity to near-Earth and geomagnetic responses.

  16. Temporal Offsets Between Maximum CME Speed Index and Solar, Geomagnetic, and Interplanetary Indicators During Solar Cycle 23 and the Ascending Phase of Cycle 24

    NASA Astrophysics Data System (ADS)

    Özgüç, A.; Kilcik, A.; Georgieva, K.; Kirov, B.

    2016-06-01

    On the basis of a morphological analysis of yearly values of the maximum coronal mass ejection (CME) speed index, the sunspot number and total sunspot area, sunspot magnetic field, and solar flare index, the solar wind speed and interplanetary magnetic field strength, and the geomagnetic Ap and D_{st} indices, we point out the particularities of solar and geomagnetic activity during the last Cycle 23, the long minimum that followed it, and the ascending branch of Cycle 24. We also analyze the temporal offset between the maximum CME speed index and the above-mentioned solar, geomagnetic, and interplanetary indices. It is found that this solar activity index, analyzed jointly with other solar activity, interplanetary parameters, and geomagnetic activity indices, shows a hysteresis phenomenon. It is observed that these parameters follow different paths for the ascending and descending phases of Cycle 23. The hysteresis phenomenon represents a clue in the search for physical processes responsible for linking the solar activity to near-Earth and geomagnetic responses.

  17. CME flux rope and shock identifications and locations: Comparison of white light data, Graduated Cylindrical Shell model, and MHD simulations

    NASA Astrophysics Data System (ADS)

    Schmidt, J. M.; Cairns, Iver H.; Xie, Hong; St. Cyr, O. C.; Gopalswamy, N.

    2016-03-01

    Coronal mass ejections (CMEs) are major transient phenomena in the solar corona that are observed with ground-based and spacecraft-based coronagraphs in white light or with in situ measurements by spacecraft. CMEs transport mass and momentum and often drive shocks. In order to derive the CME and shock trajectories with high precision, we apply the graduated cylindrical shell (GCS) model to fit a flux rope to the CME directed toward STEREO A after about 19:00 UT on 29 November 2013 and check the quality of the heliocentric distance-time evaluations by carrying out a three-dimensional magnetohydrodynamic (MHD) simulation of the same CME with the Block Adaptive Tree Solar-Wind Roe Upwind Scheme (BATS-R-US) code. Heliocentric distances of the CME and shock leading edges are determined from the simulated white light images and magnetic field strength data. We find very good agreement between the predicted and observed heliocentric distances, showing that the GCS model and the BATS-R-US simulation approach work very well and are consistent. In order to assess the validity of CME and shock identification criteria in coronagraph images, we also compute synthetic white light images of the CME and shock. We find that the outer edge of a cloud-like illuminated area in the observed and predicted images in fact coincides with the leading edge of the CME flux rope and that the outer edge of a faint illuminated band in front of the CME leading edge coincides with the CME-driven shock front.

  18. Cluster Analysis of Tumor Suppressor Genes in Canine Leukocytes Identifies Activation State

    PubMed Central

    Daly, Julie-Anne; Mortlock, Sally-Anne; Taylor, Rosanne M.; Williamson, Peter

    2015-01-01

    Cells of the immune system undergo activation and subsequent proliferation in the normal course of an immune response. Infrequently, the molecular and cellular events that underlie the mechanisms of proliferation are dysregulated and may lead to oncogenesis, leading to tumor formation. The most common forms of immunological cancers are lymphomas, which in dogs account for 8%–20% of all cancers, affecting up to 1.2% of the dog population. Key genes involved in negatively regulating proliferation of lymphocytes include a group classified as tumor suppressor genes (TSGs). These genes are also known to be associated with progression of lymphoma in humans, mice, and dogs and are potential candidates for pathological grading and diagnosis. The aim of the present study was to analyze TSG profiles in stimulated leukocytes from dogs to identify genes that discriminate an activated phenotype. A total of 554 TSGs and three gene set collections were analyzed from microarray data. Cluster analysis of three subsets of genes discriminated between stimulated and unstimulated cells. These included 20 most upregulated and downregulated TSGs, TSG in hallmark gene sets significantly enriched in active cells, and a selection of candidate TSGs, p15 (CDKN2B), p18 (CDKN2C), p19 (CDKN1A), p21 (CDKN2A), p27 (CDKN1B), and p53 (TP53) in the third set. Analysis of two subsets suggested that these genes or a subset of these genes may be used as a specialized PCR set for additional analysis. PMID:27478369

  19. B Cell Super-Enhancers and Regulatory Clusters Recruit AID Tumorigenic Activity

    PubMed Central

    Qian, Jason; Wang, Qiao; Dose, Marei; Pruett, Nathanael; Kieffer-Kwon, Kyong-Rim; Resch, Wolfgang; Liang, Genqing; Tang, Zhonghui; Mathé, Ewy; Benner, Christopher; Dubois, Wendy; Nelson, Steevenson; Vian, Laura; Oliveira, Thiago Y.; Jankovic, Mila; Hakim, Ofir; Gazumyan, Anna; Pavri, Rushad; Awasthi, Parirokh; Song, Bin; Liu, Geng; Chen, Longyun; Zhu, Shida; Feigenbaum, Lionel; Staudt, Louis; Murre, Cornelis; Ruan, Yijun; Robbiani, Davide F.; Pan-Hammarström, Qiang; Nussenzweig, Michel C.; Casellas, Rafael

    2014-01-01

    SUMMARY The antibody gene mutator activation-induced cytidine deaminase (AID) promiscuously damages oncogenes, leading to chromosomal translocations and tumorigenesis. Why nonimmunoglobulin loci are susceptible to AID activity is unknown. Here, we study AID-mediated lesions in the context of nuclear architecture and the B cell regulome. We show that AID targets are not randomly distributed across the genome but are predominantly grouped within super-enhancers and regulatory clusters. Unexpectedly, in these domains, AID deaminates active promoters and eRNA+ enhancers interconnected in some instances over megabases of linear chromatin. Using genome editing, we demonstrate that 3D-linked targets cooperate to recruit AID-mediated breaks. Furthermore, a comparison of hypermutation in mouse B cells, AID-induced kataegis in human lymphomas, and translocations in MEFs reveals that AID damages different genes in different cell types. Yet, in all cases, the targets are predominantly associated with topological complex, highly transcribed super-enhancers, demonstrating that these compartments are key mediators of AID recruitment. PMID:25483777

  20. The N-Terminal Domain of Human DNA Helicase Rtel1 Contains a Redox Active Iron-Sulfur Cluster

    PubMed Central

    Landry, Aaron P.

    2014-01-01

    Human telomere length regulator Rtel1 is a superfamily II DNA helicase and is essential for maintaining proper length of telomeres in chromosomes. Here we report that the N-terminal domain of human Rtel1 (RtelN) expressed in Escherichia coli cells produces a protein that contains a redox active iron-sulfur cluster with the redox midpoint potential of −248 ± 10 mV (pH 8.0). The iron-sulfur cluster in RtelN is sensitive to hydrogen peroxide and nitric oxide, indicating that reactive oxygen/nitrogen species may modulate the DNA helicase activity of Rtel1 via modification of its iron-sulfur cluster. Purified RtelN retains a weak binding affinity for the single-stranded (ss) and double-stranded (ds) DNA in vitro. However, modification of the iron-sulfur cluster by hydrogen peroxide or nitric oxide does not significantly affect the DNA binding activity of RtelN, suggesting that the iron-sulfur cluster is not directly involved in the DNA interaction in the N-terminal domain of Rtel1. PMID:25147792

  1. Cluster highlights in magnetospheric physics

    NASA Astrophysics Data System (ADS)

    Escoubet, C. Philippe; Laakso, Harri; Taylor, Matthew; Goldstein, Mevlyn; Hapgood, Mike; Masson, Arnaud; Volpp, Juergen; Sieg, Detlef

    The Cluster mission has been operated successfully for 14 years. As the first science mission comprising four identical spacecraft, Cluster has faced many challenges during its lifetime: its long selection process together with SOHO, the failure of the first Ariane V launch, its fast rebuilt, and the launch on two Soyuz rockets in 2000. The separation of the Cluster spacecraft was changed more than 25 times from a few kilometers up to 36000 km to address the various scientific objectives; the smallest distance achieved between two Cluster spacecraft was 4 km, about 50 times smaller than planned at the beginning of the mission. The main goal of the Cluster mission is to study in three dimensions small-scale plasma structures in key plasma regions of Earth’s geospace environment: solar wind and bow shock, magnetopause, polar cusps, magnetotail, plasmasphere and auroral zone. We will present science highlights obtained such as ripples on the bow shock, 3D current measurements and Kelvin-Helmholtz waves at the magnetopause, bifurcated current sheet in the magnetotail, and first measurement of the electron pressure tensor near a site of magnetic reconnection. In addition, we highlight Cluster results on understanding the impact of Coronal Mass Ejections (CME) on the Earth's environment. We will also present the distribution of data through the Cluster Science Data System (CSDS), and the Cluster Archive. Those systems were implemented to provide, for the first time for a plasma physics mission, a permanent and public archive of all the high resolution data from all instruments.

  2. Search for α-Cluster Structure in Exotic Nuclei with the Prototype Active-Target Time-Projection Chamber

    NASA Astrophysics Data System (ADS)

    Fritsch, A.; Ayyad, Y.; Bazin, D.; Beceiro-Novo, S.; Bradt, J.; Carpenter, L.; Cortesi, M.; Mittig, W.; Suzuki, D.; Ahn, T.; Kolata, J. J.; Becchetti, F. D.; Howard, A. M.

    2016-03-01

    Some exotic nuclei appear to exhibit α-cluster structure. While various theoretical models currently describe such clustering, more experimental data are needed to constrain model predictions. The Prototype Active-Target Time-Projection Chamber (PAT-TPC) has low-energy thresholds for charged-particle decay and a high luminosity due to its thick gaseous active target volume, making it well-suited to search for low-energy α-cluster reactions. Radioactive-ion beams produced by the TwinSol facility at the University of Notre Dame were delivered to the PAT-TPC to study nuclei including 14C and 14O via α-resonant scattering. Differential cross sections and excitation functions were measured. Preliminary results from our recent experiments will be presented. This work is supported by the U.S. National Science Foundation.

  3. A stereoscopic system for viewing the temporal evolution of brain activity clusters in response to linguistic stimuli

    NASA Astrophysics Data System (ADS)

    Forbes, Angus; Villegas, Javier; Almryde, Kyle R.; Plante, Elena

    2014-03-01

    In this paper, we present a novel application, 3D+Time Brain View, for the stereoscopic visualization of functional Magnetic Resonance Imaging (fMRI) data gathered from participants exposed to unfamiliar spoken languages. An analysis technique based on Independent Component Analysis (ICA) is used to identify statistically significant clusters of brain activity and their changes over time during different testing sessions. That is, our system illustrates the temporal evolution of participants' brain activity as they are introduced to a foreign language through displaying these clusters as they change over time. The raw fMRI data is presented as a stereoscopic pair in an immersive environment utilizing passive stereo rendering. The clusters are presented using a ray casting technique for volume rendering. Our system incorporates the temporal information and the results of the ICA into the stereoscopic 3D rendering, making it easier for domain experts to explore and analyze the data.

  4. A stereoscopic system for viewing the temporal evolution of brain activity clusters in response to linguistic stimuli.

    PubMed

    Forbes, Angus; Villegas, Javier; Almryde, Kyle R; Plante, Elena

    2014-03-01

    In this paper, we present a novel application, 3D+Time Brain View, for the stereoscopic visualization of functional Magnetic Resonance Imaging (fMRI) data gathered from participants exposed to unfamiliar spoken languages. An analysis technique based on Independent Component Analysis (ICA) is used to identify statistically significant clusters of brain activity and their changes over time during different testing sessions. That is, our system illustrates the temporal evolution of participants' brain activity as they are introduced to a foreign language through displaying these clusters as they change over time. The raw fMRI data is presented as a stereoscopic pair in an immersive environment utilizing passive stereo rendering. The clusters are presented using a ray casting technique for volume rendering. Our system incorporates the temporal information and the results of the ICA into the stereoscopic 3D rendering, making it easier for domain experts to explore and analyze the data. PMID:25075268

  5. Coronal Mass Ejections from the Same Active Region Cluster: Two Different Perspectives

    NASA Astrophysics Data System (ADS)

    Cremades, H.; Mandrini, C. H.; Schmieder, B.; Crescitelli, A. M.

    2015-06-01

    The cluster formed by active regions (ARs) NOAA 11121 and 11123, approximately located on the solar central meridian on 11 November 2010, is of great scientific interest. This complex was the site of violent flux emergence and the source of a series of Earth-directed events on the same day. The onset of the events was nearly simultaneously observed by the Atmospheric Imaging Assembly (AIA) telescope onboard the Solar Dynamics Observatory (SDO) and the Extreme-Ultraviolet Imagers (EUVI) on the Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) suite of telescopes onboard the Solar-Terrestrial Relations Observatory (STEREO) twin spacecraft. The progression of these events in the low corona was tracked by the Large Angle Spectroscopic Coronagraphs (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) and the SECCHI/COR coronagraphs on STEREO. SDO and SOHO imagers provided data from the Earth's perspective, whilst the STEREO twin instruments procured images from the orthogonal directions. This spatial configuration of spacecraft allowed optimum simultaneous observations of the AR cluster and the coronal mass ejections that originated in it. Quadrature coronal observations provided by STEREO revealed many more ejective events than were detected from Earth. Furthermore, joint observations by SDO/AIA and STEREO/SECCHI EUVI of the source region indicate that all events classified by GOES as X-ray flares had an ejective coronal counterpart in quadrature observations. These results directly affect current space weather forecasting because alarms might be missed when there is a lack of solar observations in a view direction perpendicular to the Sun-Earth line.

  6. The Role of Collagen Charge Clusters in the Modulation of Matrix Metalloproteinase Activity*

    PubMed Central

    Lauer, Janelle L.; Bhowmick, Manishabrata; Tokmina-Roszyk, Dorota; Lin, Yan; Van Doren, Steven R.; Fields, Gregg B.

    2014-01-01

    Members of the matrix metalloproteinase (MMP) family selectively cleave collagens in vivo. Several substrate structural features that direct MMP collagenolysis have been identified. The present study evaluated the role of charged residue clusters in the regulation of MMP collagenolysis. A series of 10 triple-helical peptide (THP) substrates were constructed in which either Lys-Gly-Asp or Gly-Asp-Lys motifs replaced Gly-Pro-Hyp (where Hyp is 4-hydroxy-l-proline) repeats. The stabilities of THPs containing the two different motifs were analyzed, and kinetic parameters for substrate hydrolysis by six MMPs were determined. A general trend for virtually all enzymes was that, as Gly-Asp-Lys motifs were moved from the extreme N and C termini to the interior next to the cleavage site sequence, kcat/Km values increased. Additionally, all Gly-Asp-Lys THPs were as good or better substrates than the parent THP in which Gly-Asp-Lys was not present. In turn, the Lys-Gly-Asp THPs were also always better substrates than the parent THP, but the magnitude of the difference was considerably less compared with the Gly-Asp-Lys series. Of the MMPs tested, MMP-2 and MMP-9 most greatly favored the presence of charged residues with preference for the Gly-Asp-Lys series. Lys-Gly-(Asp/Glu) motifs are more commonly found near potential MMP cleavage sites than Gly-(Asp/Glu)-Lys motifs. As Lys-Gly-Asp is not as favored by MMPs as Gly-Asp-Lys, the Lys-Gly-Asp motif appears advantageous over the Gly-Asp-Lys motif by preventing unwanted MMP hydrolysis. More specifically, the lack of Gly-Asp-Lys clusters may diminish potential MMP-2 and MMP-9 collagenolytic activity. The present study indicates that MMPs have interactions spanning the P23–P23′ subsites of collagenous substrates. PMID:24297171

  7. Pair and Cluster Formation in Hybrid Active-Passive Matter Suspensions

    NASA Astrophysics Data System (ADS)

    Krafnick, Ryan; Garcia, Angel

    2015-03-01

    Systems composed of self-propelling entities, dubbed active matter, are ubiquitous in nature, from flocks of birds and schools of fish to swarms of bacteria and catalytic nanomotors. These systems (both biological and industrial) have applications ranging from micron-scale cargo manipulation and directed transport to water remediation and material processing. When added to a solution with passive (non-self-propelling) particles, active matter leads to new and altered system properties. For example, the diffusion of passive particles increases by orders of magnitude in typical systems, leading to a raised effective temperature. Additionally, particles that normally repel each other exhibit effective attractions which can lead to pair formation and clustering. The nature of these effects depends on both the mechanical collisions of swimmers and the hydrodynamic flow fields they propagate. We computationally examine the effect and dependence of various system parameters, such as particle shape and density, on these properties. This work was funded by NIH grant GM086801 and NSF grant MCB-1050966.

  8. Symmetry adapted cluster-configuration interaction calculation of the photoelectron spectra of famous biological active steroids

    NASA Astrophysics Data System (ADS)

    Abyar, Fatemeh; Farrokhpour, Hossein

    2014-11-01

    The photoelectron spectra of some famous steroids, important in biology, were calculated in the gas phase. The selected steroids were 5α-androstane-3,11,17-trione, 4-androstane-3,11,17-trione, cortisol, cortisone, corticosterone, dexamethasone, estradiol and cholesterol. The calculations were performed employing symmetry-adapted cluster/configuration interaction (SAC-CI) method using the 6-311++G(2df,pd) basis set. The population ratios of conformers of each steroid were calculated and used for simulating the photoelectron spectrum of steroid. It was found that more than one conformer contribute to the photoelectron spectra of some steroids. To confirm the calculated photoelectron spectra, they compared with their corresponding experimental spectra. There were no experimental gas phase Hesbnd I photoelectron spectra for some of the steroids of this work in the literature and their calculated spectra can show a part of intrinsic characteristics of this molecules in the gas phase. The canonical molecular orbitals involved in the ionization of each steroid were calculated at the HF/6-311++g(d,p) level of theory. The spectral bands of each steroid were assigned by natural bonding orbital (NBO) calculations. Knowing the electronic structures of steroids helps us to understand their biological activities and find which sites of steroid become active when a modification is performing under a biological pathway.

  9. Joint Spatial-Spectral Feature Space Clustering for Speech Activity Detection from ECoG Signals

    PubMed Central

    Kanas, Vasileios G.; Mporas, Iosif; Benz, Heather L.; Sgarbas, Kyriakos N.; Bezerianos, Anastasios; Crone, Nathan E.

    2014-01-01

    Brain machine interfaces for speech restoration have been extensively studied for more than two decades. The success of such a system will depend in part on selecting the best brain recording sites and signal features corresponding to speech production. The purpose of this study was to detect speech activity automatically from electrocorticographic signals based on joint spatial-frequency clustering of the ECoG feature space. For this study, the ECoG signals were recorded while a subject performed two different syllable repetition tasks. We found that the optimal frequency resolution to detect speech activity from ECoG signals was 8 Hz, achieving 98.8% accuracy by employing support vector machines (SVM) as a classifier. We also defined the cortical areas that held the most information about the discrimination of speech and non-speech time intervals. Additionally, the results shed light on the distinct cortical areas associated with the two syllable repetition tasks and may contribute to the development of portable ECoG-based communication. PMID:24658248

  10. Peroxidase-like activity of apoferritin paired gold clusters for glucose detection.

    PubMed

    Jiang, Xin; Sun, Cuiji; Guo, Yi; Nie, Guangjun; Xu, Li

    2015-02-15

    The discovery and application of noble metal nanoclusters have received considerable attention. In this paper, we reported that apoferritin paired gold clusters (Au-Ft) could efficiently catalyze oxidation of 3.3',5.5'-tetramethylbenzidine (TMB) by H2O2 to produce a blue color reaction. Compared with natural enzyme, Au-Ft exhibited higher activity near acidic pH and could be used over a wide range of temperatures. Apoferritin nanocage enhanced the reaction activity of substrate TMB by H2O2. The reaction catalyzed by Au-Ft was found to follow a typical Michaelis-Menten kinetics. The kinetic parameters exhibited a lower K(m) value (0.097 mM) and a higher K(cat) value (5.8 × 10(4) s(-1)) for TMB than that of horse radish peroxidase (HRP). Base on these findings, Au-Ft, acting as a peroxidase mimetic, performed enzymatic spectrophotometric analysis of glucose. This system exhibited acceptable reproducibility and high selectivity in biosening, suggesting that it could have promising applications in the future. PMID:25218100

  11. The Raman and vibronic activity of intermolecular vibrations in aromatic-containing complexes and clusters

    SciTech Connect

    Maxton, P.M.; Schaeffer, M.W.; Ohline, S.M.; Kim, W.; Venturo, V.A.; Felker, P.M. )

    1994-11-15

    Theoretical and experimental results pertaining to the excitation of intermolecular vibrations in the Raman and vibronic spectra of aromatic-containing, weakly bound complexes and clusters are reported. The theoretical analysis of intermolecular Raman activity is based on the assumption that the polarizability tensor of a weakly bound species is given by the sum of the polarizability tensors of its constituent monomers. The analysis shows that the van der Waals bending fundamentals in aromatic--rare gas complexes may be expected to be strongly Raman active. More generally, it predicts strong Raman activity for intermolecular vibrations that involve the libration or internal rotation of monomer moieties having appreciable permanent polarizability anisotropies. The vibronic activity of intermolecular vibrations in aromatic-rare gas complexes is analyzed under the assumption that every vibronic band gains its strength from an aromatic-localized transition. It is found that intermolecular vibrational excitations can accompany aromatic-localized vibronic excitations by the usual Franck--Condon mechanism or by a mechanism dependent on the librational amplitude of the aromatic moiety during the course of the pertinent intermolecular vibration. The latter mechanism can impart appreciable intensity to bands that are forbidden by rigid-molecule symmetry selection rules. The applicability of such rules is therefore called into question. Finally, experimental spectra of intermolecular transitions, obtained by mass-selective, ionization-detected stimulated Raman spectroscopies, are reported for benzene--X (X=Ar, --Ar[sub 2], N[sub 2], HCl, CO[sub 2], and --fluorene), fluorobenzene--Ar and --Kr, aniline--Ar, and fluorene--Ar and --Ar[sub 2]. The results support the conclusions of the theoretical analyses and provide further evidence for the value of Raman methods in characterizing intermolecular vibrational level structures.

  12. Nanoparticle cluster gas sensor: Pt activated SnO2 nanoparticles for NH3 detection with ultrahigh sensitivity

    NASA Astrophysics Data System (ADS)

    Liu, Xu; Chen, Nan; Han, Bingqian; Xiao, Xuechun; Chen, Gang; Djerdj, Igor; Wang, Yude

    2015-09-01

    Pt activated SnO2 nanoparticle clusters were synthesized by a simple solvothermal method. The structure, morphology, chemical state and specific surface area were analyzed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2-sorption studies, respectively. The SnO2 nanoparticle cluster matrix consists of tens of thousands of SnO2 nanoparticles with an ultra-small grain size estimated to be 3.0 nm. And there are abundant random-packed wormhole-like pores, caused by the inter-connection of the SnO2 nanoparticles, throughout each cluster. The platinum element is present in two forms including metal (Pt) and tetravalent metal oxide (PtO2) in the Pt activated SnO2 nanoparticle clusters. The as-synthesized pure and Pt activated SnO2 nanoparticle clusters were used to fabricate gas sensor devices. It was found that the gas response toward 500 ppm of ammonia was improved from 6.48 to 203.44 through the activation by Pt. And the results indicate that the sensor based on Pt activated SnO2 not only has ultrahigh sensitivity but also possesses good response-recovery properties, linear dependence, repeatability, selectivity and long-term stability, demonstrating the potential to use Pt activated SnO2 nanoparticle clusters as ammonia gas sensors. At the same time, the formation mechanisms of the unique nanoparticle clusters and highly enhanced sensitivity are also discussed.Pt activated SnO2 nanoparticle clusters were synthesized by a simple solvothermal method. The structure, morphology, chemical state and specific surface area were analyzed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2-sorption studies, respectively. The SnO2 nanoparticle cluster matrix consists of tens of thousands of SnO2 nanoparticles with an ultra-small grain size estimated to be 3.0 nm. And there are abundant random-packed wormhole-like pores, caused by the inter

  13. Initial fluxon models of CME onset: loss-of-equilibrium, breakout, tether-cutting

    NASA Astrophysics Data System (ADS)

    Deforest, C.

    2005-12-01

    I will present results from initial models of CME onset using a new force-free magnetic evolution code, FLUX, that uses the novel fluxon approach to MHD modeling. FLUX is a quasi-Lagrangian solver that is free of numerical reconnection and that I am making available as free software. It is currently suitable for studying evolving force-free equilibria in the presence of only controlled reconnection; development work is ongoing to add plasma static and dynamic forces. I plan to consider three simple configurations typical of three current genres of CME onset model: loss of equilibrium under smooth motion by the photosphere; "tether-cutting" (reconnection of a containment field underneath a twisted prominence field); and "breakout" (reconnection of a containment field above a twisted prominence field). In each case I will estimate the magnetic energy available to accelerate mass, and discuss the resulting shape of the remnant open field regions ("dimming regions") after liftoff.

  14. Thyroid function testing in eastern Nepal and the impact of CME on subsequent requests.

    PubMed

    Baral, N; Koner, B C; Lamsal, M; Niraula, I; Dhungel, S

    2001-07-01

    This study reveals 1 year's experience of the introduction of thyroid function tests (TFT) in B P Koirala Institute of Health Sciences (BPKIHS), a Medical University situated in eastern Nepal. These were performed on theadvice of doctors working in this region. The rational TFT advice by the medical practitioners was evaluated according to how closely the advice was in line with the algorithms recommended in the textbooks. Only about 14% of the TFT advice followed some rational strategy. A retrospective analysis showed that rational TFT advice could have reduced the cost of a TFT investigation to 43.11% without altering the patient management and disease outcome. Continuing medical education (CME) lectures arranged for a limited number of doctors were found to improve the quality of the subsequentTFT advising pattern. This emphasizes the importance of CME while introducing a costly laboratory test panel (e.g.TFT, lipid profile) needing a strategic approach. PMID:11444339

  15. Modeling CME-shock-driven storms in 2012-2013: MHD test particle simulations

    NASA Astrophysics Data System (ADS)

    Hudson, M. K.; Paral, J.; Kress, B. T.; Wiltberger, M.; Baker, D. N.; Foster, J. C.; Turner, D. L.; Wygant, J. R.

    2015-02-01

    The Van Allen Probes spacecraft have provided detailed observations of the energetic particles and fields environment for coronal mass ejection (CME)-shock-driven storms in 2012 to 2013 which have now been modeled with MHD test particle simulations. The Van Allen Probes orbital plane longitude moved from the dawn sector in 2012 to near midnight and prenoon for equinoctial storms of 2013, providing particularly good measurements of the inductive electric field response to magnetopause compression for the 8 October 2013 CME-shock-driven storm. An abrupt decrease in the outer boundary of outer zone electrons coincided with inward motion of the magnetopause for both 17 March and 8 October 2013 storms, as was the case for storms shortly after launch. Modeling magnetopause dropout events in 2013 with electric field diagnostics that were not available for storms immediately following launch have improved our understanding of the complex role that ULF waves play in radial transport during such events.

  16. Methane Activation Mediated by a Series of Cerium-Vanadium Bimetallic Oxide Cluster Cations: Tuning Reactivity by Doping.

    PubMed

    Ma, Jia-Bi; Meng, Jing-Heng; He, Sheng-Gui

    2016-04-18

    The reactions of cerium-vanadium cluster cations Cex Vy Oz (+) with CH4 are investigated by time-of-flight mass spectrometry and density functional theory calculations. (CeO2 )m (V2 O5 )n (+) clusters (m=1,2, n=1-5; m=3, n=1-4) with dimensions up to nanosize can abstract one hydrogen atom from CH4 . The theoretical study indicates that there are two types of active species in (CeO2 )m (V2 O5 )n (+) , V[(Ot )2 ](.) and [(Ob )2 CeOt ](.) (Ot and Ob represent terminal and bridging oxygen atoms, respectively); the former is less reactive than the latter. The experimentally observed size-dependent reactivities can be rationalized by considering the different active species and mechanisms. Interestingly, the reactivity of the (CeO2 )m (V2 O5 )n (+) clusters falls between those of (CeO2 )2-4 (+) and (V2 O5 )1-5 (+) in terms of C-H bond activation, thus the nature of the active species and the cluster reactivity can be effectively tuned by doping. PMID:26714587

  17. Assembly of Fe-substituted Dawson-type nanoscale selenotungstate clusters with photocatalytic H2 evolution activity.

    PubMed

    Chen, Wei-Chao; Qin, Chao; Wang, Xin-Long; Li, Yang-Guang; Zang, Hong-Ying; Jiao, Yan-Qing; Huang, Peng; Shao, Kui-Zhan; Su, Zhong-Min; Wang, En-Bo

    2014-11-11

    Two Fe-substituted Dawson-type nanoscale selenotungstate clusters, {Fe6Se6W34} and {Fe10Se8W62} involving {α-Se2W14} and {γ-Se2W14} building blocks, have been isolated, which exhibit photocatalytic H2 evolution activity. Their electrochemical behaviours and magnetic properties were also investigated. PMID:25232933

  18. The Dependence of Characteristic Times of Gradual SEP Events on Their Associated CME Properties

    NASA Astrophysics Data System (ADS)

    Pan, Z. H.; Wang, C. B.; Xue, X. H.; Wang, Y. M.

    It is generally believed that coronal mass ejections CMEs are the drivers of shocks that accelerate gradual solar energetic particles SEPs One might expect that the characteristics of the SEP intensity time profiles observed at 1 AU are determined by properties of the associated CMEs such as the radial speed and the angular width Recently Kahler statistically investigated the characteristic times of gradual SEP events observed from 1998-2002 and their associated coronal mass ejection properties Astrophys J 628 1014--1022 2005 Three characteristic times of gradual SEP events are determined as functions of solar source longitude 1 T 0 the time from associated CME launch to SEP onset at 1 AU 2 T R the rise time from SEP onset to the time when the SEP intensity is a factor of 2 below peak intensity and 3 T D the duration over which the SEP intensity is within a factor of 2 of the peak intensity However in his study the CME speeds and angular widths are directly taken from the LASCO CME catalog In this study we analyze the radial speeds and the angular widths of CMEs by an ice-cream cone model and re-investigate their correlationships with the characteristic times of the corresponding SEP events We find T R and T D are significantly correlated with radial speed for SEP events in the best-connected longitude range and there is no correlation between T 0 and CME radial speed and angular width which is consistent with Kahler s results On the other hand it s found that T R and T D are also have

  19. Charge state composition in coronal hole and CME related solar wind: Latitudinal variations observed by Ulysses and WIND

    NASA Technical Reports Server (NTRS)

    Galvin, A. B.; Gloeckler, G.

    1997-01-01

    Iron charge states in recurrent coronal hole-associated solar wind flows are obtained in the ecliptic by WIND/SMS, while measurements of iron and silicon from the polar coronal holes are available from Ulysses/SWICS. Ulysses/SWICS also provides ion composition of coronal mass ejection (CME)-related solar wind. Both coronal hole-associated and CME-related solar wind charge charges show heliographic latitudinal variations.

  20. NUMERICAL SIMULATION OF AN EUV CORONAL WAVE BASED ON THE 2009 FEBRUARY 13 CME EVENT OBSERVED BY STEREO

    SciTech Connect

    Cohen, Ofer; Attrill, Gemma D. R.; Wills-Davey, Meredith J.; Manchester, Ward B.

    2009-11-01

    On 2009 February 13, a coronal wave-CME-dimming event was observed in quadrature by the Solar Terrestrial Relations Observatory (STEREO) spacecraft. We analyze this event using a three-dimensional, global magnetohydrodynamic model for the solar corona. The numerical simulation is driven and constrained by the observations, and indicates where magnetic reconnection occurs between the expanding CME core and surrounding environment. We focus primarily on the lower corona, extending out to 3 R{sub sun}; this range allows simultaneous comparison with both EUVI and COR1 data. Our simulation produces a diffuse coronal bright front remarkably similar to that observed by STEREO/EUVI at 195 A. It is made up of two components, and is the result of a combination of both wave and non-wave mechanisms. The CME becomes large-scale quite low (< 200 Mm) in the corona. It is not, however, an inherently large-scale event; rather, the expansion is facilitated by magnetic reconnection between the expanding CME core and the surrounding magnetic environment. In support of this, we also find numerous secondary dimmings, many far from the initial CME source region. Relating such dimmings to reconnecting field lines within the simulation provides further evidence that CME expansion leads to the 'opening' of coronal field lines on a global scale. Throughout the CME expansion, the coronal wave maps directly to the CME footprint. Our results suggest that the ongoing debate over the 'true' nature of diffuse coronal waves may be mischaracterized. It appears that both wave and non-wave models are required to explain the observations and understand the complex nature of these events.

  1. Heliospheric remote imaging and its relation to CME input to solar wind propagation models

    NASA Astrophysics Data System (ADS)

    Pizzo, V. J.; Biesecker, D. A.; Millward, G. H.; Odstrcil, D.

    2011-12-01

    The process of transitioning the WSA-Enlil solar wind forecast model into operations at the National Weather Service provides an opportunity to reconsider the nature of CME inputs as determined from coronagraph and heliospheric imaging observations. At present, the model uses an extremely simple hydrodynamic pulse (increase in density and speed over the inferred angular extent of the CME) to mimic the driver gas at the base of the interplanetary (IP) regime. However, it is clear from recent events (as well as from analyses of STEREO/LASCO events by others) that the form of the CME in the corona is in many cases quite complex, such that it is unclear what input to provide to this model or any IP model. It appears that fast CMEs in particular consist - in the corona - of a visible mass driver (with significant magnetic structure) surrounded by a strong, spreading wavefront. What is important for forecasting is to understand what part of that full structure actually contributes to the IP propagation, and what part dissipates near the near Sun. A serious study of the propagation of strong shocks in a structured corona and out into the hyperalvenic regime is one element needed to improve modeling capabilities; another would be to tie the coronal observations to more distant heliospheric imagery for a collection of such events.

  2. Initiation of CMEs associated with filament eruption, and the nature of CME related shocks

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    Using data from SDO, PROBA2 and other spacecraft, Fainshtein and Egorov (2013) have discovered processes accompanying initiation of six limb CMEs and have studied features of their motion. The said CMEs occurred after eruption of prominence or hot emission loop and were associated with X-ray flares. The follow-up study of the CMEs, associated with the prominence eruption, showed that the formation of such mass ejections and the initial stage of their motion may be characterised by special features. In this work, we give examples of CMEs with such features. We have revealed a positive correlation between the height of the CME-related eruptive prominence and the height of the frontal structure of CMEs measured before they began to move. By analysing two of the CMEs, using SDO data, we found out that the kinematics of CME body and its related shock differs considerably. We have established that the time dependence of shock position and velocity obtained from SDO data is in agreement with theoretical dependencies of variation in these motion parameters with time in the context of self-similar motion of an explosion shock. We have concluded that the shock are not piston-like with the CME body acting as a piston.

  3. 3D MHD Simulations of the May 2, 1998 halo CME: Shock formation and SEP acceleration

    NASA Astrophysics Data System (ADS)

    Sokolov, I. V.; Roussev, I. I.; Gombosi, T. I.; Forbes, T. G.; Lee, M. A.

    We present the results of two numerical models of the partial-halo CME event associated with NOAA AR8210 on May 2, 1998. Our simulations are fully three-dimensional and involve compressible magnetohydrodynamics with turbulent energy transport. We begin by first producing a steady-state solar wind for Carrington Rotation 1935/6, following the methodology described in Roussev et al. (2003). We impose shearing motions along the polarity inversion line of AR8210, followed by converging motions, both via the modification of the boundary conditions at the Sun's surface. As a consequence, a flux rope forms within the sheared arcade during the CME. The flux rope gradually accelerates, leaving behind the remnants of a flare loop system that results from ongoing magnetic reconnection in the naturally formed current sheet. The flux rope leaves the Sun, forming a CME emerging through a highly structured, ambient solar wind. A shock wave forms in front of the ejected matter. Estimates for the spectral index and cutoff energy for the diffusive solar energetic particle shock acceleration mechanism show that the protons can be efficiently accelerated up to energies 0.1-10 GeV.

  4. Automated Prediction of CMEs Using Machine Learning of CME - Flare Associations

    NASA Astrophysics Data System (ADS)

    Qahwaji, R.; Colak, T.; Al-Omari, M.; Ipson, S.

    2008-04-01

    Machine-learning algorithms are applied to explore the relation between significant flares and their associated CMEs. The NGDC flares catalogue and the SOHO/LASCO CME catalogue are processed to associate X and M-class flares with CMEs based on timing information. Automated systems are created to process and associate years of flare and CME data, which are later arranged in numerical-training vectors and fed to machine-learning algorithms to extract the embedded knowledge and provide learning rules that can be used for the automated prediction of CMEs. Properties representing the intensity, flare duration, and duration of decline and duration of growth are extracted from all the associated (A) and not-associated (NA) flares and converted to a numerical format that is suitable for machine-learning use. The machine-learning algorithms Cascade Correlation Neural Networks (CCNN) and Support Vector Machines (SVM) are used and compared in our work. The machine-learning systems predict, from the input of a flare’s properties, if the flare is likely to initiate a CME. Intensive experiments using Jack-knife techniques are carried out and the relationships between flare properties and CMEs are investigated using the results. The predictive performance of SVM and CCNN is analysed and recommendations for enhancing the performance are provided.

  5. Metabolic risk profiles created using cluster analysis are differentially associated with physical activity: The ARIC study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conditions such as hypertension, dyslipidemia, glucose intolerance, and obesity tend to cluster together and predict cardiovascular disease, type 2 diabetes, and premature mortality. This clustering has led to multiple definitions of the Metabolic Syndrome (MetS). While the definitions agree on the ...

  6. A systematic investigation of acetylene activation and hydracyanation of the activated acetylene on Aun (n = 3-10) clusters via density functional theory.

    PubMed

    Gautam, Seema; Sarkar, Abir De

    2016-05-18

    A systematic investigation of the selective catalytic conversion of poisonous HCN gas through hydracyanation of C2H2 activated on Au clusters, presented here for the first time, is of paramount importance from both scientific and technological perspectives. Hydracyanation of activated acetylene on an Au-cluster based catalyst leads to vinyl isocyanide (H2C[double bond, length as m-dash]CHNC) formation, a versatile chemical intermediate. Using density functional theory, bond activation of acetylene and selective catalytic hydracyanation of activated acetylene on small gold clusters Aun (n = 3-10) have been studied through a detailed analysis of the geometric and electronic structures. Different possible complexes of Aun-CHCH have been studied and two possible modes of adsorption of acetylene over the gold clusters, namely, the π- and di-σ modes, have been observed. The hydracyanation of the acetylene molecule is found to occur via the cleavage of one of acetylene triple bonds at the cost of formation of two Au-C bonds followed by the binding of HCN to the activated C[double bond, length as m-dash]C bond via nitrogen's lone pair. Preferential binding sites for HCN and C2H2 are analyzed through Fukui function calculations, frontier molecular orbital analysis and natural population charge distribution analysis. Based on adsorption energies, odd-sized Aun clusters are found to be significantly more favorable for C2H2 adsorption with the C-C bond stretching up to 1.31 Å with respect to the C-C triple bond length of 1.21 Å in the gas phase. The stretching frequency of adsorbed complexes, C2H2/Aun, (3460 cm(-1)), decreases notably relative to the frequency of the free acetylene molecule (7948 cm(-1)), which is a signature of the bond activation of the acetylene molecule over the Au clusters. The high adsorption energy of HCN on the Au9-C2H2 complex implies the considerable binding strength and activation of C2H2 and HCN on the Au9 clusters. Due to the importance of

  7. Tracking the CME-driven shock wave on 2012 March 5 and radio triangulation of associated radio emission

    SciTech Connect

    Magdalenić, J.; Marqué, C.; Mierla, M.; Zhukov, A. N.; Rodriguez, L.; Krupar, V.; Maksimović, M.; Cecconi, B.

    2014-08-20

    We present a multiwavelength study of the 2012 March 5 solar eruptive event, with an emphasis on the radio triangulation of the associated radio bursts. The main points of the study are reconstruction of the propagation of shock waves driven by coronal mass ejections (CMEs) using radio observations and finding the relative positions of the CME, the CME-driven shock wave, and its radio signatures. For the first time, radio triangulation is applied to different types of radio bursts in the same event and performed in a detailed way using goniopolarimetric observations from STEREO/Waves and WIND/Waves spacecraft. The event on 2012 March 5 was associated with a X1.1 flare from the NOAA AR 1429 situated near the northeast limb, accompanied by a full halo CME and a radio event comprising long-lasting interplanetary type II radio bursts. The results of the three-dimensional reconstruction of the CME (using SOHO/LASCO, STEREO COR, and HI observations), and modeling with the ENLIL cone model suggest that the CME-driven shock wave arrived at 1 AU at about 12:00 UT on March 7 (as observed by SOHO/CELIAS). The results of radio triangulation show that the source of the type II radio burst was situated on the southern flank of the CME. We suggest that the interaction of the shock wave and a nearby coronal streamer resulted in the interplanetary type II radio emission.

  8. On the combination of ACE data with numerical simulations to determine the initial characteristics of a CME

    NASA Astrophysics Data System (ADS)

    Chané, E.; Poedts, S.; van der Holst, B.

    2008-12-01

    Aims: Our goal is to combine the Advanced Composition Explorer (ACE) data with numerical simulations to determine the initial characteristics of the halo coronal mass ejection (CME), which was observed on April 4, 2000. Methods: The evolution of a CME from the Sun to 1 AU is simulated in the framework of 2.5 D (axi-symmetric) ideal Magnetohydrodynamics (MHD). The initial parameters of the CME model are adjusted to reproduce the ACE data as accurately as possible. The initial parameters leading to the best fit are then assumed to be the most plausible initial parameters of the CME event. Results: Once the ACE data and the transit time were successfully reproduced, we concluded that, at 1.5 R_⊙, the CME had a maximal magnetic field strength of 2.5 × 10-4 T and a total mass of 6.7 × 1012 kg, and the CME linear speed up to 30 R_⊙ was 1524 km s-1.

  9. Redox Control of the Human Iron-Sulfur Repair Protein MitoNEET Activity via Its Iron-Sulfur Cluster.

    PubMed

    Golinelli-Cohen, Marie-Pierre; Lescop, Ewen; Mons, Cécile; Gonçalves, Sergio; Clémancey, Martin; Santolini, Jérôme; Guittet, Eric; Blondin, Geneviève; Latour, Jean-Marc; Bouton, Cécile

    2016-04-01

    Human mitoNEET (mNT) is the first identified Fe-S protein of the mammalian outer mitochondrial membrane. Recently, mNT has been implicated in cytosolic Fe-S repair of a key regulator of cellular iron homeostasis. Here, we aimed to decipher the mechanism by which mNT triggers its Fe-S repair capacity. By using tightly controlled reactions combined with complementary spectroscopic approaches, we have determined the differential roles played by both the redox state of the mNT cluster and dioxygen in cluster transfer and protein stability. We unambiguously demonstrated that only the oxidized state of the mNT cluster triggers cluster transfer to a generic acceptor protein and that dioxygen is neither required for the cluster transfer reaction nor does it affect the transfer rate. In the absence of apo-acceptors, a large fraction of the oxidized holo-mNT form is converted back to reduced holo-mNT under low oxygen tension. Reduced holo-mNT, which holds a [2Fe-2S](+)with a global protein fold similar to that of the oxidized form is, by contrast, resistant in losing its cluster or in transferring it. Our findings thus demonstrate that mNT uses an iron-based redox switch mechanism to regulate the transfer of its cluster. The oxidized state is the "active state," which reacts promptly to initiate Fe-S transfer independently of dioxygen, whereas the reduced state is a "dormant form." Finally, we propose that the redox-sensing function of mNT is a key component of the cellular adaptive response to help stress-sensitive Fe-S proteins recover from oxidative injury. PMID:26887944

  10. The Activity of Rabies Vaccines against Genetic Clusters of Rabies Virus Circulating at the Territory of Ukraine

    PubMed Central

    Ivanov, Mykola; Polupan, Ivan; Deryabin, Oleg

    2013-01-01

    Objective To identify the presence of genetic clusters of rabies virus at the territory of Ukraine and to determine the degree of activity of rabies vaccines against these genetic clusters. Introduction To develop and implement an effective program of rabies eradication in Ukraine in 2008 was founded the unique collection of samples of pathological materials confirmed as positive in rabies at the regional veterinary laboratories of Ukraine. The collection is constantly updated and to present moment it includes 1389 samples from all regions of Ukraine, selected from 17 animal species and humans. Methods Identification of the rabies virus in samples of pathological material for their further selection was carried out using the test developed by us which based on RT-PCR with primers complementary to the conservative fragments of the 5’-end of nucleoprotein gene of rabies virus. For the study of the street rabies virus isolates from the collection we use RT-PCR with the primers pair (509, 304) flanking the variable 3’-end part of nucleoprotein gene of the reference strain of rabies virus CVS (fragment in 377 bp). Studies of rabies vaccines activity were carried out with modified method of U.S. National Institutes of Health using rabies virus street isolates of both genetic clusters instead of the Challenge Virus Standard (CVS). All isolates of street rabies virus were inoculated in a dose of 5–50 LD50. The criteria for evaluation of protective activity of rabies vaccine was effective dose (− lg ED50). Results In molecular genetic studies with variant-specific primers we established the presence in Ukraine of two clusters of rabies virus. Clusters I circulates on the right bank of the Dnipro river (the largest water barrier that divides the country into eastern and western side), and cluster II – on the left bank of the Dnieper. The relationship of these variants with the epizootic situation was researched. For this purpose epizootological zoning of Ukraine

  11. Using SOHO to Understand CME-Producing Quiet-Region Filament Eruptions

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.; Moore, R. L.; Harra, L. K.

    2006-01-01

    In recent years we have been studying solar eruptions in an attempt to determine their primary initiation mechanism. We have focused on events involving filaments, because motions of the filaments just prior to their violent eruption are indicative of changes in the entire magnetic field system involved in the eruption. When the pre-eruption filament resides in a quiet region, the motions leading up to eruption are slower than in similar eruptions in active regions due to the weaker magnetic field strength and correspondingly lower Alfven velocities. These early motions manifest themselves in a slow rise (a few km/s) of the filament, in some cases lasting several hours. After this the filament and associated magnetic structures erupt rapidly, accelerating to speeds of a few 10 kmh over a few minutes. Because of their slow evolution, quiet-region eruptions such as these can be effectively studied in EUV with SOHO/EIT, with its regular cadence of about 12 min. For several cases we have combined EIT images with SOHO/MDI magnetograms and data from other other instruments, and compared our observations with predictions from various eruption scenarios, in particular the "breakout" (Antiochos 1998), "tether cutting" (e.g., Moore et al. 2001), and MHD instability mechanisms. Here we present a representative example of a quiet-region eruption involving a filament ejection, that occurred on 2001 February 28 in a magnetically quadrupolar region and produced a halo CME in SOHO/LASCO images. In addition to EIT and MDI, we analyzed spectral data from SOHO/CDS and soft X-ray (SXR) images from Yohkoh/SXT. We found that flux emergence occurred near one end of the filament, and that both this emergence and resulting microflaring in SXRs and EUV were temporally and spatially closely related to the start of the filament's slow rise. Intensity changes (dimmings and brightenings) in the EIT and SXT images indicate that fields far removed from the erupting core were involved in the

  12. Screen-based media use clusters are related to other activity behaviours and health indicators in adolescents

    PubMed Central

    2013-01-01

    Background Screen-based media (SBM) occupy a considerable portion of young peoples’ discretionary leisure time. The aim of this paper was to investigate whether distinct clusters of SBM use exist, and if so, to examine the relationship of any identified clusters with other activity/sedentary behaviours and physical and mental health indicators. Methods The data for this study come from 643 adolescents, aged 14 years, who were participating in the longitudinal Western Australian Pregnancy Cohort (Raine) Study through May 2003 to June 2006. Time spent on SBM, phone use and reading was assessed using the Multimedia Activity Recall for Children and Adults. Height, weight, muscle strength were measured at a clinic visit and the adolescents also completed questionnaires on their physical activity and psychosocial health. Latent class analysis (LCA) was used to analyse groupings of SBM use. Results Three clusters of SBM use were found; C1 ‘instrumental computer users’ (high email use, general computer use), C2 ‘multi-modal e-gamers’ (both high console and computer game use) and C3 ‘computer e-gamers’ (high computer game use only). Television viewing was moderately high amongst all the clusters. C2 males took fewer steps than their male peers in C1 and C3 (-13,787/week, 95% CI: -4619 to -22957, p = 0.003 and -14,806, 95% CI: -5,306 to -24,305, p = 0.002) and recorded less MVPA than the C1 males (-3.5 h, 95% CI: -1.0 to -5.9, p = 0.005). There was no difference in activity levels between females in clusters C1 and C3. Conclusion SBM use by adolescents did cluster and these clusters related differently to activity/sedentary behaviours and both physical and psychosocial health indicators. It is clear that SBM use is not a single construct and future research needs to take consideration of this if it intends to understand the impact SBM has on health. PMID:24330626

  13. High interfacial activity of polymers "grafted through" functionalized iron oxide nanoparticle clusters.

    PubMed

    Foster, Lynn M; Worthen, Andrew J; Foster, Edward L; Dong, Jiannan; Roach, Clarissa M; Metaxas, Athena E; Hardy, Clifford D; Larsen, Eric S; Bollinger, Jonathan A; Truskett, Thomas M; Bielawski, Christopher W; Johnston, Keith P

    2014-09-01

    The mechanism by which polymers, when grafted to inorganic nanoparticles, lower the interfacial tension at the oil-water interface is not well understood, despite the great interest in particle stabilized emulsions and foams. A simple and highly versatile free radical "grafting through" technique was used to bond high organic fractions (by weight) of poly(oligo(ethylene oxide) monomethyl ether methacrylate) onto iron oxide clusters, without the need for catalysts. In the resulting ∼1 μm hybrid particles, the inorganic cores and grafting architecture contribute to the high local concentration of grafted polymer chains to the dodecane/water interface to produce low interfacial tensions of only 0.003 w/v % (polymer and particle core). This "critical particle concentration" (CPC) for these hybrid inorganic/polymer amphiphilic particles to lower the interfacial tension by 36 mN/m was over 30-fold lower than the critical micelle concentration of the free polymer (without inorganic cores) to produce nearly the same interfacial tension. The low CPC is favored by the high adsorption energy (∼10(6) kBT) for the large ∼1 μm hybrid particles, the high local polymer concentration on the particles surfaces, and the ability of the deformable hybrid nanocluster cores as well as the polymer chains to conform to the interface. The nanocluster cores also increased the entanglement of the polymer chains in bulk DI water or synthetic seawater, producing a viscosity up to 35,000 cP at 0.01 s(-1), in contrast with only 600 cP for the free polymer. As a consequence of these interfacial and rheological properties, the hybrid particles stabilized oil-in-water emulsions at concentrations as low as 0.01 w/v %, with average drop sizes down to 30 μm. In contrast, the bulk viscosity was low for the free polymer, and it did not stabilize the emulsions. The ability to influence the interfacial activity and rheology of polymers upon grafting them to inorganic particles, including clusters

  14. Star Formation and AGN Activity in Galaxy Clusters from z=1-2: a Multi-Wavelength Analysis Featuring Herschel/PACS

    NASA Astrophysics Data System (ADS)

    Alberts, Stacey; Pope, Alexandra; Brodwin, Mark; Chung, Sun Mi; Cybulski, Ryan; Dey, Arjun; Eisenhardt, Peter R. M.; Galametz, Audrey; Gonzalez, Anthony H.; Jannuzi, Buell T.; Stanford, S. Adam; Snyder, Gregory F.; Stern, Daniel; Zeimann, Gregory R.

    2016-07-01

    We present a detailed, multi-wavelength study of star formation (SF) and active galactic nucleus (AGN) activity in 11 near-infrared (IR) selected, spectroscopically confirmed massive (≳1014 M ⊙) galaxy clusters at 1 < z < 1.75. Using new deep Herschel/PACS imaging, we characterize the optical to far-IR spectral energy distributions (SEDs) for IR-luminous cluster galaxies, finding that they can, on average, be well described by field galaxy templates. Identification and decomposition of AGNs through SED fittings allows us to include the contribution to cluster SF from AGN host galaxies. We quantify the star-forming fraction, dust-obscured SF rates (SFRs) and specific SFRs for cluster galaxies as a function of cluster-centric radius and redshift. In good agreement with previous studies, we find that SF in cluster galaxies at z ≳ 1.4 is largely consistent with field galaxies at similar epochs, indicating an era before significant quenching in the cluster cores (r < 0.5 Mpc). This is followed by a transition to lower SF activity as environmental quenching dominates by z ∼ 1. Enhanced SFRs are found in lower mass (10.1\\lt {log} {M}\\star /{M}ȯ \\lt 10.8) cluster galaxies. We find significant variation in SF from cluster to cluster within our uniformly selected sample, indicating that caution should be taken when evaluating individual clusters. We examine AGNs in clusters from z = 0.5–2, finding an excess AGN fraction at z ≳ 1, suggesting environmental triggering of AGNs during this epoch. We argue that our results—a transition from field-like to quenched SF, enhanced SF in lower mass galaxies in the cluster cores, and excess AGNs—are consistent with a co-evolution between SF and AGNs in clusters and an increased merger rate in massive halos at high redshift.

  15. Hydrogen activation, diffusion, and clustering on CeO₂(111): a DFT+U study.

    PubMed

    Fernández-Torre, Delia; Carrasco, Javier; Ganduglia-Pirovano, M Verónica; Pérez, Rubén

    2014-07-01

    We present a comprehensive density functional theory+U study of the mechanisms underlying the dissociation of molecular hydrogen, and diffusion and clustering of the resulting atomic species on the CeO2(111) surface. Contrary to a widely held view based solely on a previous theoretical prediction, our results show conclusively that H2 dissociation is an activated process with a large energy barrier ~1.0 eV that is not significantly affected by coverage or the presence of surface oxygen vacancies. The reaction proceeds through a local energy minimum--where the molecule is located close to one of the surface oxygen atoms and the H-H bond has been substantially weaken by the interaction with the substrate--, and a transition state where one H atom is attached to a surface O atom and the other H atom sits on-top of a Ce(4+) ion. In addition, we have explored how several factors, including H coverage, the location of Ce(3+) ions as well as the U value, may affect the chemisorption energy and the relative stability of isolated OH groups versus pair and trimer structures. The trimer stability at low H coverages and the larger upward relaxation of the surface O atoms within the OH groups are consistent with the assignment of the frequent experimental observation by non-contact atomic force and scanning tunneling microscopies of bright protrusions on three neighboring surface O atoms to a triple OH group. The diffusion path of isolated H atoms on the surface goes through the adsorption on-top of an oxygen in the third atomic layer with a large energy barrier of ~1.8 eV. Overall, the large energy barriers for both, molecular dissociation and atomic diffusion, are consistent with the high activity and selectivity found recently in the partial hydrogenation of acetylene catalyzed by ceria at high H2/C2H2 ratios. PMID:25005299

  16. Mitochondrial Iron-Sulfur Cluster Activity and Cytosolic Iron Regulate Iron Traffic in Saccharomyces cerevisiae.

    PubMed

    Wofford, Joshua D; Lindahl, Paul A

    2015-11-01

    An ordinary differential equation-based mathematical model was developed to describe trafficking and regulation of iron in growing fermenting budding yeast. Accordingly, environmental iron enters the cytosol and moves into mitochondria and vacuoles. Dilution caused by increasing cell volume is included. Four sites are regulated, including those in which iron is imported into the cytosol, mitochondria, and vacuoles, and the site at which vacuolar Fe(II) is oxidized to Fe(III). The objective of this study was to determine whether cytosolic iron (Fecyt) and/or a putative sulfur-based product of iron-sulfur cluster (ISC) activity was/were being sensed in regulation. The model assumes that the matrix of healthy mitochondria is anaerobic, and that in ISC mutants, O2 diffuses into the matrix where it reacts with nonheme high spin Fe(II) ions, oxidizing them to nanoparticles and generating reactive oxygen species. This reactivity causes a further decline in ISC/heme biosynthesis, which ultimately gives rise to the diseased state. The ordinary differential equations that define this model were numerically integrated, and concentrations of each component were plotted versus the concentration of iron in the growth medium and versus the rate of ISC/heme biosynthesis. Model parameters were optimized by fitting simulations to literature data. The model variant that assumed that both Fecyt and ISC biosynthesis activity were sensed in regulation mimicked observed behavior best. Such "dual sensing" probably arises in real cells because regulation involves assembly of an ISC on a cytosolic protein using Fecyt and a sulfur species generated in mitochondria during ISC biosynthesis and exported into the cytosol. PMID:26306041

  17. Star Formation Activity in a Young Galaxy Cluster at Z = 0.866

    NASA Astrophysics Data System (ADS)

    Laganá, T. F.; Ulmer, M. P.; Martins, L. P.; da Cunha, E.

    2016-07-01

    The galaxy cluster RX J1257+4738 at z = 0.866 is one of the highest redshift clusters with a richness of multi-wavelength data, and is thus a good target to study the star formation–density relation at early epochs. Using a sample of spectroscopically confirmed cluster members, we derive the star-formation rates (SFRs) of our galaxies using two methods: (1) the relation between SFR and total infrared luminosity extrapolated from the observed Spitzer Multiband Imaging Photometer for Spitzer 24 μm imaging data; and (2) spectral energy distribution fitting using the MAGPHYS code, including eight different bands. We show that, for this cluster, the SFR–density relation is very weak and seems to be dominated by the two central galaxies and the SFR presents a mild dependence on stellar mass, with more massive galaxies having higher SFR. However, the specific SFR (SSFR) decreases with stellar mass, meaning that more massive galaxies are forming fewer stars per unit of mass, and thus suggesting that the increase in star-forming members is driven by cluster assembly and infall. If the environment is somehow driving the star formation, one would expect a relation between the SSFR and the cluster centric distance, but that is not the case. A possible scenario to explain this lack of correlation is the contamination by infalling galaxies in the inner part of the cluster, which may be on their initial pass through the cluster center. As these galaxies have higher SFRs for their stellar mass, they enhance the mean SSFR in the center of the cluster.

  18. Asp1 from Schizosaccharomyces pombe binds a [2Fe-2S](2+) cluster which inhibits inositol pyrophosphate 1-phosphatase activity.

    PubMed

    Wang, Huanchen; Nair, Vasudha S; Holland, Ashley A; Capolicchio, Samanta; Jessen, Henning J; Johnson, Michael K; Shears, Stephen B

    2015-10-27

    Iron-sulfur (Fe-S) clusters are widely distributed protein cofactors that are vital to cellular biochemistry and the maintenance of bioenergetic homeostasis, but to our knowledge, they have never been identified in any phosphatase. Here, we describe an iron-sulfur cluster in Asp1, a dual-function kinase/phosphatase that regulates cell morphogenesis in Schizosaccharomyces pombe. Full-length Asp1, and its phosphatase domain (Asp1(371-920)), were each heterologously expressed in Escherichia coli. The phosphatase activity is exquisitely specific: it hydrolyzes the 1-diphosphate from just two members of the inositol pyrophosphate (PP-InsP) signaling family, namely, 1-InsP7 and 1,5-InsP8. We demonstrate that Asp1 does not hydrolyze either InsP6, 2-InsP7, 3-InsP7, 4-InsP7, 5-InsP7, 6-InsP7, or 3,5-InsP8. We also recorded 1-phosphatase activity in a human homologue of Asp1, hPPIP5K1, which was heterologously expressed in Drosophila S3 cells with a biotinylated N-terminal tag, and then isolated from cell lysates with avidin beads. Purified, recombinant Asp1(371-920) contained iron and acid-labile sulfide, but the stoichiometry (0.8 atoms of each per protein molecule) indicates incomplete iron-sulfur cluster assembly. We reconstituted the Fe-S cluster in vitro under anaerobic conditions, which increased the stoichiometry to approximately 2 atoms of iron and acid-labile sulfide per Asp1 molecule. The presence of a [2Fe-2S](2+) cluster in Asp1(371-920) was demonstrated by UV-visible absorption, resonance Raman spectroscopy, and electron paramagnetic resonance spectroscopy. We determined that this [2Fe-2S](2+) cluster is unlikely to participate in redox chemistry, since it rapidly degraded upon reduction by dithionite. Biochemical and mutagenic studies demonstrated that the [2Fe-2S](2+) cluster substantially inhibits the phosphatase activity of Asp1, thereby increasing its net kinase activity. PMID:26422458

  19. High reactivity of nanosized niobium oxide cluster cations in methane activation: A comparison with vanadium oxides.

    PubMed

    Ding, Xun-Lei; Wang, Dan; Wu, Xiao-Nan; Li, Zi-Yu; Zhao, Yan-Xia; He, Sheng-Gui

    2015-09-28

    The reactions between methane and niobium oxide cluster cations were studied and compared to those employing vanadium oxides. Hydrogen atom abstraction (HAA) reactions were identified over stoichiometric (Nb2O5)N(+) clusters for N as large as 14 with a time-of-flight mass spectrometer. The reactivity of (Nb2O5)N(+) clusters decreases as the N increases, and it is higher than that of (V 2O5)N(+) for N ≥ 4. Theoretical studies were conducted on (Nb2O5)N(+) (N = 2-6) by density functional calculations. HAA reactions on these clusters are all favorable thermodynamically and kinetically. The difference of the reactivity with respect to the cluster size and metal type (Nb vs V) was attributed to thermodynamics, kinetics, the electron capture ability, and the distribution of the unpaired spin density. Nanosized Nb oxide clusters show higher HAA reactivity than V oxides, indicating that niobia may serve as promising catalysts for practical methane conversion. PMID:26429016

  20. High reactivity of nanosized niobium oxide cluster cations in methane activation: A comparison with vanadium oxides

    SciTech Connect

    Ding, Xun-Lei E-mail: chemzyx@iccas.ac.cn; Wang, Dan; Wu, Xiao-Nan; Li, Zi-Yu; Zhao, Yan-Xia E-mail: chemzyx@iccas.ac.cn; He, Sheng-Gui

    2015-09-28

    The reactions between methane and niobium oxide cluster cations were studied and compared to those employing vanadium oxides. Hydrogen atom abstraction (HAA) reactions were identified over stoichiometric (Nb{sub 2}O{sub 5}){sub N}{sup +} clusters for N as large as 14 with a time-of-flight mass spectrometer. The reactivity of (Nb{sub 2}O{sub 5}){sub N}{sup +} clusters decreases as the N increases, and it is higher than that of (V {sub 2}O{sub 5}){sub N}{sup +} for N ≥ 4. Theoretical studies were conducted on (Nb{sub 2}O{sub 5}){sub N}{sup +} (N = 2–6) by density functional calculations. HAA reactions on these clusters are all favorable thermodynamically and kinetically. The difference of the reactivity with respect to the cluster size and metal type (Nb vs V) was attributed to thermodynamics, kinetics, the electron capture ability, and the distribution of the unpaired spin density. Nanosized Nb oxide clusters show higher HAA reactivity than V oxides, indicating that niobia may serve as promising catalysts for practical methane conversion.

  1. MC2: boosted AGN and star formation activity in CIZA J2242.8+5301, a massive post-merger cluster at z = 0.19

    NASA Astrophysics Data System (ADS)

    Sobral, David; Stroe, Andra; Dawson, William A.; Wittman, David; Jee, M. James; Röttgering, Huub; van Weeren, Reinout J.; Brüggen, Marcus

    2015-06-01

    Cluster mergers may play a fundamental role in the formation and evolution of cluster galaxies. Stroe et al. revealed unexpected overdensities of candidate Hα emitters near the ˜1-Mpc-wide shock fronts of the massive (˜2 × 1015 M⊙) `Sausage' merging cluster, CIZA J2242.8+5301. We used the Keck/Deep Imaging Multi-Object Spectrograph and the William Herschel Telescope/AutoFib2+WYFFOS to confirm 83 Hα emitters in and around the merging cluster. We find that cluster star-forming galaxies in the hottest X-ray gas and/or in the cluster subcores (away from the shock fronts) show high [S II]6716/[S II]6761 and high [S II] 6716/Hα, implying very low electron densities (<30 × lower than all other star-forming galaxies outside the cluster) and/or significant contribution from supernovae, respectively. All cluster star-forming galaxies near the cluster centre show evidence of significant outflows (blueshifted Na D ˜200-300 km s-1), likely driven by supernovae. Strong outflows are also found for the clusteractive galactic nucleus (AGN). Hα star-forming galaxies in the merging cluster follow the z ˜ 0 mass-metallicity relation, showing systematically higher metallicity (˜0.15-0.2 dex) than Hα emitters outside the cluster (projected R > 2.5 Mpc). This suggests that the shock front may have triggered remaining metal-rich gas which galaxies were able to retain into forming stars. Our observations show that the merger of impressively massive (˜1015 M⊙) clusters can provide the conditions for significant star formation and AGN activity, but, as we witness strong feedback by star-forming galaxies and AGN (and given how massive the merging cluster is), such sources will likely quench in a few 100 Myr.

  2. Prediction of Type II Burst Radiation for Large CME Events

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Type IIs are associated with shocks in the corona and solar wind, either driven by CMEs or else blast waves. Recent quantitative theories for type II radiation show that the amount of radiation depends on the speed and spatial extent of the 3D shock, as well as on the background plasma, magnetic field configuration, and the number of superthermal electrons available for acceleration by the shock. In principle, then, Type II bursts may provide 1-3 day warnings of large and fast CMEs that might produce space weather at Earth. In this paper we couple the advanced 3D MHD BATS-R-US code of Toth, Gombosi, and colleagues with our new ``bolt-on'' theory for type II emission. The modeling includes initialization with coronal and active region magnetic fields reconstructed from solar magnetograms, coronal densities determined by 1 AU data, and CMEs modelled using STEREO coronagraph data. Two events with type IIs and strong CMEs are analyzed: 15 February 2011 and 7 March 2012. We demonstrate impressive accuracy in time, frequency, and intensity for both type II bursts. This strongly supports the type II theory, implies real understanding of the physics involved, and supports the near-term development of a capability to predict and track these events for space weather prediction.

  3. White spot syndrome virus entry is dependent on multiple endocytic routes and strongly facilitated by Cq-GABARAP in a CME-dependent manner.

    PubMed

    Chen, Rong-Yuan; Shen, Kai-Li; Chen, Zhen; Fan, Wei-Wei; Xie, Xiao-Lu; Meng, Chuang; Chang, Xue-Jiao; Zheng, Li-Bing; Jeswin, Joseph; Li, Cheng-Hua; Wang, Ke-Jian; Liu, Hai-Peng

    2016-01-01

    White spot syndrome virus (WSSV) is a lethal pathogen of shrimp and many other crustaceans, including crayfish. However, the molecular mechanism underlying its cellular entry remains elusive due to the lack of shrimp cell lines for viral propagation. Crayfish hematopoietic tissue (Hpt) cell culture was recently established as a good model for WSSV infection study. Here, we showed that multiple endocytic routes, including clathrin-mediated endocytosis (CME), macropinocytosis and caveolae-mediated endocytosis, were indispensably employed for the viral entry into Hpt cell of the crayfish Cherax quadricarinatus. Intriguingly, cellular autophagic activity was positively correlated with efficient viral entry, in which a key autophagy-related protein, γ-aminobutyric acid receptor-associated protein (Cq-GABARAP), that not only localized but also co-localized with WSSV on the Hpt cell membrane, strongly facilitated WSSV entry by binding to the viral envelope VP28 in a CME-dependent manner that was negatively regulated by Cq-Rac1. Furthermore, cytoskeletal components, including Cq-β-tubulin and Cq-β-actin, bound to both recombinant rCq-GABARAP and WSSV envelope proteins, which likely led to viral entry promotion via cooperation with rCq-GABARAP. Even under conditions that promoted viral entry, rCq-GABARAP significantly reduced viral replication at an early stage of infection, which was probably caused by the formation of WSSV aggregates in the cytoplasm. PMID:27385304

  4. White spot syndrome virus entry is dependent on multiple endocytic routes and strongly facilitated by Cq-GABARAP in a CME-dependent manner

    PubMed Central

    Chen, Rong-yuan; Shen, Kai-li; Chen, Zhen; Fan, Wei-wei; Xie, Xiao-lu; Meng, Chuang; Chang, Xue-jiao; Zheng, Li-bing; Jeswin, Joseph; Li, Cheng-hua; Wang, Ke-jian; Liu, Hai-peng

    2016-01-01

    White spot syndrome virus (WSSV) is a lethal pathogen of shrimp and many other crustaceans, including crayfish. However, the molecular mechanism underlying its cellular entry remains elusive due to the lack of shrimp cell lines for viral propagation. Crayfish hematopoietic tissue (Hpt) cell culture was recently established as a good model for WSSV infection study. Here, we showed that multiple endocytic routes, including clathrin-mediated endocytosis (CME), macropinocytosis and caveolae-mediated endocytosis, were indispensably employed for the viral entry into Hpt cell of the crayfish Cherax quadricarinatus. Intriguingly, cellular autophagic activity was positively correlated with efficient viral entry, in which a key autophagy-related protein, γ-aminobutyric acid receptor-associated protein (Cq-GABARAP), that not only localized but also co-localized with WSSV on the Hpt cell membrane, strongly facilitated WSSV entry by binding to the viral envelope VP28 in a CME-dependent manner that was negatively regulated by Cq-Rac1. Furthermore, cytoskeletal components, including Cq-β-tubulin and Cq-β-actin, bound to both recombinant rCq-GABARAP and WSSV envelope proteins, which likely led to viral entry promotion via cooperation with rCq-GABARAP. Even under conditions that promoted viral entry, rCq-GABARAP significantly reduced viral replication at an early stage of infection, which was probably caused by the formation of WSSV aggregates in the cytoplasm. PMID:27385304

  5. Flare-CME Models: An Observational Perspective (Invited Review)

    NASA Astrophysics Data System (ADS)

    Schmieder, B.; Aulanier, G.; Vršnak, B.

    2015-12-01

    Eruptions, flares, and coronal mass ejection (CMEs) are due to physical phenomena mainly driven by an initially force-free current-carrying magnetic field. We review some key observations relevant to the current theoretical trigger mechanisms of the eruption and to the energy release via reconnection. Sigmoids observed in X-rays and UV, as well as the pattern (double J-shaped) of electric currents in the photosphere show clear evidence of the existence of currents parallel to the magnetic field and can be the signature of a flux rope that is detectable in CMEs. The magnetic helicity of filaments and active regions is an interesting indirectly measurable parameter because it can quantify the twist of the flux rope. On the other hand, the magnetic helicity of the solar structures allows us to associate solar eruptions and magnetic clouds in the heliosphere. The magnetic topology analysis based on the 3D magnetic field extrapolated from vector magnetograms is a good tool for identifying the reconnection locations (null points and/or the 3D large volumes - hyperbolic flux tube, HFT). Flares are associated more with quasi-separatrix layers (QSLs) and HFTs than with a single null point, which is a relatively rare case. We review various mechanisms that have been proposed to trigger CMEs and their observable signatures: by "breaking" the field lines overlying the flux rope or by reconnection below the flux rope to reduce the magnetic tension, or by letting the flux rope to expand until it reaches a minimum threshold height (loss of equilibrium or torus instability). Additional mechanisms are commonly operating in the solar atmosphere. Examples of observations are presented throughout the article and are discussed in this framework.

  6. The Properties of Solar Energetic Particle Event-Associated Coronal Mass Ejections Reported in Different CME Catalogs

    NASA Astrophysics Data System (ADS)

    Richardson, I. G.; von Rosenvinge, T. T.; Cane, H. V.

    2015-06-01

    We compare estimates of the speed and width of coronal mass ejections (CMEs) in several catalogs for the CMEs associated with ˜ 200 solar energetic particle (SEP) events in 2006 - 2013 that included 25 MeV protons. The catalogs used are: CDAW, CACTUS, SEEDS, and CORIMP, all derived from observations by the LASCO coronagraphs on the SOHO spacecraft, the CACTUS catalog derived from the COR2 coronagraphs on the STEREO-A and -B spacecraft, and the DONKI catalog, which uses observations from SOHO and the STEREO spacecraft. We illustrate how, for this set of events, CME parameters can differ considerably in each catalog. The well-known correlation between CME speed and proton event intensity is shown to be similar for most catalogs, but this is largely because it is determined by a few large particle events associated with fast CMEs, and small events associated with slow CMEs. Intermediate particle events "shuffle" in position when speeds from different catalogs are used. Quadrature spacecraft CME speeds do not improve the correlation. CME widths also vary widely between catalogs, and they are influenced by plane-of-the-sky projection and how the width is inferred from the coronagraph images. The high degree of association (˜ 50 %) between the 25 MeV proton events and "full halo" (360∘-width) CMEs as defined in the CDAW catalog is removed when other catalogs are considered. Using CME parameters from the quadrature spacecraft, the SEP intensity is correlated with CME width, which is also correlated with CME speed.

  7. Transit time of CME/shock associated with four major geo-effective CMEs in solar cycle 24

    NASA Astrophysics Data System (ADS)

    Syed Ibrahim, M.; Shanmugaraju, A.; Bendict Lawrance, M.

    2015-01-01

    The kinematics of coronal mass ejection (CME) in the interplanetary medium is very important in the concept of space-weather. Main aim of this paper is to study the propagation of four major geo-effective CMEs and their associated shocks observed in solar cycle 24. The arrival of interplanetary shocks and CMEs of these events near the Earth is seen from the ACE/wind in situ data available in OMNI data base. The CMEs considered in this study have a wide range of initial speeds 500-1900 km/s in the LASCO field of view, comprising of two slow CMEs (V ∼ 500 km/s), one fast CME (V ∼ 1800 km/s) and one moderate speed CME (V ∼ 800 km/s). The observed transit time of these events are compared with transit time estimated using the empirical shock arrival model (ESA). Especially, we utilize (i) different acceleration - speed equations reported in the literature from the observations made in the last few decades and (ii) various acceleration cessation distances (Acd) In addition, we compared the estimated and observed transit time with that from the Drag Based Model (DBM). From the result of this analysis, we demonstrated that each CME behaves in its own way in the interplanetary medium and their propagation is governed by the CME initial speed, interplanetary acceleration and acceleration cessation distances. In the present paper, we found (i) which acceleration equation is better for the transit time calculations (ii) importance of the CME acceleration cessation distances (iii) reducing the transit time error in CME forecasting. Based on these results and on Zhao and Dryer (2014) review (that included physics-based models), the realistic statistics should be based on real-time studies, not on post-mortem case studies.

  8. Intervention Effects on Adolescent Physical Activity in the Multicomponent SPACE Study: A Cluster Randomized Controlled Trial

    PubMed Central

    Toftager, Mette; Christiansen, Lars B.; Ersbøll, Annette K.; Kristensen, Peter L.; Due, Pernille; Troelsen, Jens

    2014-01-01

    Background Multicomponent school-based interventions have the potential to reduce the age-related decline in adolescents' physical activity (PA), yet there is not consistent evidence to guide non-curricular and school environment interventions. The aim of this study was to assess the effectiveness of a multicomponent environmental school-based intervention, designed to reduce the age-related decline in PA among adolescents. Methods A cluster randomized controlled trial was conducted with 7 intervention and 7 control schools. Baseline measurements were carried out in spring 2010 with 2 years of follow-up. A total of 1,348 students (11–13 years, in grade 5 and 6) enrolled in the study at baseline. The 14 schools included in the study were located in the Region of Southern Denmark. The intervention consisted of organizational and physical changes in the school environment with a total of 11 intervention components. The primary outcome measure was overall PA (cpm, counts per minute) and was supported by analyses of time spent in MVPA, and time spent sedentary. Furthermore, a secondary outcome measure was PA in school time and during recess. PA was measured using accelerometer (Actigraph GT3X). Results A total of 797 students completed the trial and had valid accelerometer data. No significant difference was found for overall PA with an adjusted difference of −19.1 cpm (95% CI: −93, 53) or for school time activity with an adjusted difference of 6 cpm (95% CI: −73, 85). A sensitivity analysis revealed a positive significant intervention effect of PA in recess with an adjusted difference of 95 cpm. Conclusions No evidence was found of the overall effect of a non-curricular multicomponent school-based intervention on PA among Danish adolescents. The intervention was positively associated with PA during school time and recess, however, with small estimates. Lack of effect on overall PA could be due to both program theory and different degrees of implementation

  9. Serum paraoxonase activity is associated with variants in the PON gene cluster and risk of Alzheimer disease.

    PubMed

    Erlich, Porat M; Lunetta, Kathryn L; Cupples, L Adrienne; Abraham, Carmela R; Green, Robert C; Baldwin, Clinton T; Farrer, Lindsay A

    2012-05-01

    Previous studies have shown association of single nucleotide polymorphisms (SNPs) in 3 contiguous genes (PON1, PON2, and PON3) encoding paraoxonase with risk of Alzheimer disease (AD). We evaluated the association of serum paraoxonase activity measured by phenyl acetate (PA) and thiobutyl butyrolactone (TBBL) with risk of AD and with 26 SNPs spanning the PON gene cluster in 266 AD cases and 306 sibling controls from the MIRAGE study. The odds of AD (adjusted for age, gender, and ethnicity) increased 20% for each standard deviation decrease in PA or TBBL activity. There were association signals with activity in all 3 genes. Haplotypes including SNPs spanning the PON genes were generally more significant than haplotypes comprising SNPs from 1 gene. Significant interactions were observed between SNP pairs located across the PON cluster with either serum activity measure as the outcome, and between several PON SNPs and PA activity with AD status as the outcome. Our results suggest that low serum paraoxonase activity is a risk factor for AD. Furthermore, multiple variants in PON influence serum paraoxonase activity and their effects may be synergistic. PMID:20980077

  10. An Introduction to the New Data Streaming and Data Mining Services Provided by the ESA Cluster Active Archive

    NASA Astrophysics Data System (ADS)

    Perry, C. H.; McCaffrey, S.; Laakso, H. E.; Taylor, M. G.

    2011-12-01

    The Cluster Active Archive has been operating since 2006 and is the principal repository for high quality data from the European Space Agency's cornerstone space physics Cluster mission. The archive holds nearly 10 years of high resolution in-situ plasma, particles and waves data from the 11 instruments on each of the four Cluster spacecraft. The archive has more than 1200 registered users and includes processed science data amounting to tens of terabytes of time series data divided into around 1400 logical datasets. We present an introduction to the capabilities and implementation of two new web based services that have been developed to enhance access to the archive data holdings and to assisting science users in locating intervals of scientific interest. i. The new data streaming service supports requests for arbitrary lengths of time series data from a single dataset and supplements the existing web GUI and machine interfaces. The service is primarily aimed at science tool developers who want a simple REST based mechanism to load Cluster data into their application. ii. The data mining service, which makes use of the streaming interface, allows the construction of complex conditions incorporating multiple datasets to identify lists of time intervals of interest for further analysis. For example searching a year of data for tail crossings (identified by rapid change in the azimuth direction of the magnetic field), when the spacecraft is in Burst Mode involves joining three independent datasets and takes about 30 seconds.

  11. Synthesis and SAR requirements of adamantane-colchicine conjugates with both microtubule depolymerizing and tubulin clustering activities.

    PubMed

    Zefirova, Olga N; Nurieva, Evgeniya V; Shishov, Dmitrii V; Baskin, Igor I; Fuchs, Fabian; Lemcke, Heiko; Schröder, Fabian; Weiss, Dieter G; Zefirov, Nikolay S; Kuznetsov, Sergei A

    2011-09-15

    A series of analogues of conjugate 1, combining an adamantane-based paclitaxel (taxol) mimetic with colchicine was synthesized and tested for cytotoxicity in a cell-based assay with the human lung carcinoma cell line A549. The most active compounds (10 EC(50) 2 ± 1.0 nM, 23 EC(50) 6 ± 1.4 nM, 26 EC(50) 5 ± 1.8 nM, 28 EC(50) 11 ± 1.7 nM, 30 EC(50) 4.8 ± 0.5 nM) were found to interfere with the microtubule dynamics in an interesting manner. Treatment of the cells with these compounds promoted disassembly of microtubules followed by the formation of stable tubulin clusters. Structure-activity relationships for the analogues of 23 revealed the sensitivity of both cytotoxicity and tubulin clustering ability to the linker length. The presence of adamantane (or another bulky hydrophobic and non-aromatic moiety) in 23 was found to play an important role in the formation of tubulin clusters. Structural requirements for optimal activity have been partially explained by molecular modeling. PMID:21873068

  12. Activation and Transformation of Ethane by Au2 VO3(+) Clusters with Closed-Shell Electronic Structures.

    PubMed

    Li, Ya-Ke; Li, Zi-Yu; Zhao, Yan-Xia; Liu, Qing-Yu; Meng, Jing-Heng; He, Sheng-Gui

    2016-01-26

    The study of chemical reactions between gold-containing heteronuclear oxide clusters and small molecules can provide molecular level mechanisms to understand the excellent activity of gold supported by metal oxides. While the promotion role of gold in alkane transformation was identified in the clusters with atomic oxygen radicals (O(-.)), the role of gold in the systems without O(-.) is not clear. By employing mass spectrometry and quantum chemistry calculations, the reactivity of Au2 VO3(+) clusters with closed-shell electronic structures toward ethane was explored. Both the dehydrogenation and ethene elimination channels were identified. It is gold rather than oxygen species initiating the C-H activation. The Au-Au dimer formed during the reactions plays important roles in ethane transformation. The reactivity comparison between Au2 VO3(+) and bare Au2(+) demonstrates that Au2 VO3(+) not only retains the property of bare Au2(+) that transforming ethane to dihydrogen, but also exhibits new functions in converting ethane to ethene, which reveals the importance of the composite system. This study provides a further understanding of the reactivity of metal oxide supported gold in alkane activation and transformation. PMID:26679978

  13. Investigation of CME properties using the data of SDO and PROBA2 spacecraft

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    Formation and motion (at the initial stage) of six limb CMEs detected in the period June 2010 to June 2011 are investigated using the high-resolution data of the PROBA2 and SDO spacecraft combined with the data of SOHO/LASCO coronagraphs. It is demonstrated that several loop-like structures of enhanced brightness originate in the region of CME formation, and they move one after another with, as a rule, different velocities. These loop-like structures in the final analysis form the frontal structure of CME. Time dependences of the velocity and acceleration of the ejection's front are obtained for all CMEs under consideration. A conclusion is drawn about possible existence of two classes of CMEs depending on their velocity time profiles. Ejections, whose velocity after reaching its maximum sharply drops by a value of more than 100 km/s and then goes over into a regime of slow change, belong to the first class. Another class of CMEs is formed by ejections whose velocity changes slowly immediately after reaching the maximum. It is demonstrated that the CME's angular dimension increases at the initial stage of ejection motion up to a factor of 3 with a time scale of doubling the angular size value within the limits 3.5-11 min since the moment of the first measurement of this parameter of an ejection. For three CMEs it is shown that at the initial stage of their motion for a certain time interval they are stronger expanded than grow in the longitude direction.

  14. AN INTERPRETATION OF GLE71 CONCURRENT CME-DRIVEN SHOCK WAVE

    SciTech Connect

    Firoz, Kazi A.; Rodríguez-Pacheco, J.; Zhang, Q. M.; Gan, W. Q.; Li, Y. P.; Moon, Y.-J.; Kudela, K.; Park, Y.-D.; Dorman, Lev I. E-mail: firoz.kazi@uah.es

    2014-08-01

    Particle accelerations in solar flares and CME-driven shocks can sometimes result in very high-energy particle events (≥1 GeV) that are known as ground level enhancements (GLEs). Recent studies on the first GLE event (GLE71 2012 May 17 01:50 UT) of solar cycle 24 suggested that CME-driven shock played a leading role in causing the event. To verify this claim, we have made an effort to interpret the GLE71 concurrent shock wave. For this, we have deduced the possible speed and height of the shock wave in terms of the frequency (MHz) of the solar radio type II burst and its drift rate (MHz min{sup –1}), and studied the temporal evolution of the particle intensity profiles at different heights of the solar corona. For a better perception of the particle acceleration in the shock, we have studied the solar radio type II burst with concurrent solar radio and electron fluxes. When the particle intensity profiles are necessarily shifted in time at ∼1 AU, it is found that the growth phases of the electron and cosmic ray intensity fluxes are strongly correlated (>0.91; ≥0.87) with the frequency drift rate of the type II burst, which is also consistent with the intensive particle accelerations at upper coronal heights (∼≥0.80 R {sub S} < 1.10 R {sub S}). Thus, we conclude that the CME-driven shock was possibly capable of producing the high-energy particle event. However, since the peaks of some flare components are found to be strongly associated with the fundamental phase of the type II burst, the preceding flare is supposed to contribute to the shock acceleration process.

  15. ElEvoHI - Improving CME arrival predictions using heliospheric imaging

    NASA Astrophysics Data System (ADS)

    Rollett, Tanja; Möstl, Christian; Isavnin, Alexey; Kubicka, Manuel; Amerstorfer, Ute; Davies, Jackie; Harrison, Richard

    2016-04-01

    The STEREO mission has sampled a tremendous amount of data, which have served as a basis to develop a lot of new methods to analyze the dynamics of coronal mass ejections (CMEs) during their journey through interplanetary space. The STEREO heliospheric imagers (HI) in particular are unsurpassed in their contribution to a deeper understanding of how CMEs are influenced by interaction with the solar wind and other CMEs and how they evolve in the inner heliosphere. Although STEREO is currently not well observing the space between the Sun and Earth, the large data repository of HI observations enables us to further improve the prediction of CME arrival times and speeds using HI observations - particularly with regard to a potential future L5 mission. We present a new method for predicting arrival times and speeds of CMEs at any location in the inner heliosphere: ElEvoHI. This new approach uses HI observations as input and assumes an elliptic CME front shape. The solar wind influence is taken into account by fitting the observations using the drag-based model. In this way, it is possible to gain all parameters needed as input for the Ellipse Evolution model (ElEvo), which is then used to predict the CME arrival. To demonstrate the applicability of ElEvoHI we present the forecasts for 20 CMEs remotely observed by STEREO/HI and compare the forecasts to their in situ arrival times and speeds at 1 AU. Compared to the widely used Fixed-φ fitting method, ElEvoHI improves the arrival time forecast by 2.2 hours to ±6.5 hours and the arrival speed forecast by 260 km s‑1 to ±55 km s‑1. In particular, the remarkable improvement of the arrival speed prediction is crucial for predicting geomagnetic storm strength on Earth.

  16. Magnetohydrodynamic simulation of interplanetary propagation of multiple coronal mass ejections with internal magnetic flux rope (SUSANOO-CME)

    NASA Astrophysics Data System (ADS)

    Shiota, D.; Kataoka, R.

    2016-02-01

    Coronal mass ejections (CMEs) are the most important drivers of various types of space weather disturbance. Here we report a newly developed magnetohydrodynamic (MHD) simulation of the solar wind, including a series of multiple CMEs with internal spheromak-type magnetic fields. First, the polarity of the spheromak magnetic field is set as determined automatically according to the Hale-Nicholson law and the chirality law of Bothmer and Schwenn. The MHD simulation is therefore capable of predicting the time profile of the southward interplanetary magnetic field at the Earth, in relation to the passage of a magnetic cloud within a CME. This profile is the most important parameter for space weather forecasts of magnetic storms. In order to evaluate the current ability of our simulation, we demonstrate a test case: the propagation and interaction process of multiple CMEs associated with the highly complex active region NOAA 10486 in October to November 2003, and present the result of a simulation of the solar wind parameters at the Earth during the 2003 Halloween storms. We succeeded in reproducing the arrival at the Earth's position of a large amount of southward magnetic flux, which is capable of causing an intense magnetic storm. We find that the observed complex time profile of the solar wind parameters at the Earth could be reasonably well understood by the interaction of a few specific CMEs.

  17. Comparison Between Hot and Cool Ejections in CME/Flare Events

    NASA Astrophysics Data System (ADS)

    Nitta, N. V.

    2001-05-01

    Comparison between hot and cool ejections in CME/flare events Nariaki Nitta (LMSAL) , Sachiko Akiyama (GUAS) We have shown that high-temperature ejections during the impulsive phase of flares as seen with Yohkoh/SXT are correlated with coronal mass ejections (CMEs) as seen by SOHO/LASCO. Since then we have collected a number of examples of ejections observed with TRACE. In this presentation, we compare ejections in soft X-rays with those in H-alpha and EUV, and study the sequence of processes (reconnection, mass motion, heating, etc.) involved in CMEs so that we can put more constraints on the models.

  18. Comparison of the WSA-ENLIL model with three CME cone types

    NASA Astrophysics Data System (ADS)

    Jang, Soojeong; Moon, Y.; Na, H.

    2013-07-01

    We have made a comparison of the CME-associated shock propagation based on the WSA-ENLIL model with three cone types using 29 halo CMEs from 2001 to 2002. These halo CMEs have cone model parameters as well as their associated interplanetary (IP) shocks. For this study we consider three different cone types (an asymmetric cone model, an ice-cream cone model and an elliptical cone model) to determine 3-D CME parameters (radial velocity, angular width and source location), which are the input values of the WSA-ENLIL model. The mean absolute error (MAE) of the arrival times for the asymmetric cone model is 10.6 hours, which is about 1 hour smaller than those of the other models. Their ensemble average of MAE is 9.5 hours. However, this value is still larger than that (8.7 hours) of the empirical model of Kim et al. (2007). We will compare their IP shock velocities and densities with those from ACE in-situ measurements and discuss them in terms of the prediction of geomagnetic storms.Abstract (2,250 Maximum Characters): We have made a comparison of the CME-associated shock propagation based on the WSA-ENLIL model with three cone types using 29 halo CMEs from 2001 to 2002. These halo CMEs have cone model parameters as well as their associated interplanetary (IP) shocks. For this study we consider three different cone types (an asymmetric cone model, an ice-cream cone model and an elliptical cone model) to determine 3-D CME parameters (radial velocity, angular width and source location), which are the input values of the WSA-ENLIL model. The mean absolute error (MAE) of the arrival times for the asymmetric cone model is 10.6 hours, which is about 1 hour smaller than those of the other models. Their ensemble average of MAE is 9.5 hours. However, this value is still larger than that (8.7 hours) of the empirical model of Kim et al. (2007). We will compare their IP shock velocities and densities with those from ACE in-situ measurements and discuss them in terms of the

  19. The Driving Magnetic Field and Reconnection in CME/Flare Eruptions and Coronal Jets

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.

    2010-01-01

    Signatures of reconnection in major CME (coronal mass ejection)/flare eruptions and in coronal X-ray jets are illustrated and interpreted. The signatures are magnetic field lines and their feet that brighten in flare emission. CME/flare eruptions are magnetic explosions in which: 1. The field that erupts is initially a closed arcade. 2. At eruption onset, most of the free magnetic energy to be released is not stored in field bracketing a current sheet, but in sheared field in the core of the arcade. 3. The sheared core field erupts by a process that from its start or soon after involves fast "tether-cutting" reconnection at an initially small current sheet low in the sheared core field. If the arcade has oppositely-directed field over it, the eruption process from its start or soon after also involves fast "breakout" reconnection at an initially small current sheet between the arcade and the overarching field. These aspects are shown by the small area of the bright field lines and foot-point flare ribbons in the onset of the eruption. 4. At either small current sheet, the fast reconnection progressively unleashes the erupting core field to erupt with progressively greater force. In turn, the erupting core field drives the current sheet to become progressively larger and to undergo progressively greater fast reconnection in the explosive phase of the eruption, and the flare arcade and ribbons grow to become comparable to the pre-eruption arcade in lateral extent. In coronal X-ray jets: 1. The magnetic energy released in the jet is built up by the emergence of a magnetic arcade into surrounding unipolar "open" field. 2. A simple jet is produced when a burst of reconnection occurs at the current sheet between the arcade and the open field. This produces a bright reconnection jet and a bright reconnection arcade that are both much smaller in diameter that the driving arcade. 3. A more complex jet is produced when the arcade has a sheared core field and undergoes an

  20. Speed evolution of CME/shocks using multi-spacecraft observations of type II radio bursts: A case study

    NASA Astrophysics Data System (ADS)

    Manuel-Hernandez, T.; Aguilar-Rodriguez, E.; Gonzalez-Esparza, J. A.; Ontiveros, V.

    2013-06-01

    We present a study which focuses on the speed evolution of a coronal mass ejection (CME)/shock associated with a type II radio burst observed on January 25, 2007. The type II burst feature had a multi-spacecraft coverage, being detected by the Wind/WAVES and the STEREO/WAVES radio instruments in the frequency range of 14 MHz to 90 kHz. The CME associated with the type II radio burst was observed by the SOHO/LASCO and the STEREO/SECCHI coronographs. Ground-based radio observations of the metric type II burst counterpart were obtained by the Bruny Island Radio Spectrometer (BIRS) in the frequency range of 40 MHz to 25 MHz. We analyzed the combined white-light and radio observations to infer the speed evolution of the CME/shock event. The CME/shock speed from the different data sets shows a significant deceleration near to the Sun followed by a slow and gradual deceleration in the interplanetary medium, which is consistent with the expected evolution of fast CME/shocks. Multi-spacecraft and combined white-light and radio observations are important to gain insight into the tracking of solar transients which propagate in the inner heliosphere.

  1. The CME Rate over Four Solar Cycles: Filling the Final Gap with MLSO MK3 Observations [1989-1996

    NASA Astrophysics Data System (ADS)

    St Cyr, O. C.; Flint, Q.; Quirk, C. A.; Burkepile, J.; Webb, D. F.; Lecinski, A. R.

    2013-12-01

    Coronal mass ejections (CMEs) were discovered in the early 1970's by the OSO-7 coronagraph, and large numbers were characterized for the first time by the Skylab ATM coronagraph. Since 1973 there has been only a single major gap in CME coverage in white light. Instruments that have contributed to estimates of the rate and properties of CMEs have included: Skylab ATM (1973-1974); Helios photometers (1974-1981); Solwind (1979-1985); SMM C/P (1980; 1984-1989); SOHO LASCO (1996-present); the Solar Mass Ejection Imager (SMEI, 2003-2011); and STEREO SECCHI (2006-present). We report here the first attempt to fill the 1989-1996 gap in the CME rate using the Mauna Loa Solar Observatory's MK3 K-coronameter. The MK3 instrument observed routinely several hours most days beginning in 1980 until it was upgraded to MK4 in 1998. MK3 CMEs detected from 1980-1989 were compared with Solwind and SMM and reported by St. Cyr et al. (1999). Since spaceborne instruments have more complete duty cycles than a groundbased instrument at a single location, we have 'calibrated' the MK3-derived CME rate from 1989 with the SMM C/P coronagraph, and from 1996 with the SOHO LASCO coronagraphs. CME rate calculations have been documented in Webb & Howard (1994), St. Cyr et al. (2000) and Robbrecht et al. (2009). Here we provide the preliminary CME rate calculation for 1989-1996 using the MLSO MK3 coronameter.

  2. Costimulation with anti-cluster of differentiation 3 and anti-cluster of differentiation 28 reduces the activity of mucin 1-stimulated human mononuclear cells

    PubMed Central

    WRIGHT, STEPHEN E.; REWERS-FELKINS, KATHLEEN A.; QUINLIN, IMELDA; ZOHRA, FATEMA; AHMED, JEWEL

    2016-01-01

    Cytotoxic T-lymphocyte activation and extension of the cell life span is necessary in order to enable immunotherapy to perform effectively against cancer. In the present study, mucin 1 (MUC1)-stimulated human mononuclear cells (M1SHMCs) were costimulated with bead-attached monoclonal antibodies specific for cluster of differentiation (CD)3 and CD28 receptors. The study was undertaken to determine whether costimulation was capable of enhancing the killing of cancer cells in vitro and of protecting non-obese diabetic severe combined immunodeficient mice from tumor development. Lysis of MCF-7 tumor cells by M1SHMCs was reduced following costimulation with anti-CD3 and anti-CD28. Furthermore, costimulation with anti-CD3 and anti-CD28 eliminated the protective effects of M1SHMCs on MCF-7 breast cancer cell growth in the non-obese diabetic severe combined immunodeficient mice. The present study suggested that costimulation with anti-CD3 and anti-CD28 is not advisable following antigen activation of lymphocytes under the conditions used here. Using a lower anti-CD3/CD28 bead to T-cell ratio may prevent immune suppression, however, further studies are required to support this hypothesis. PMID:26870234

  3. Phosphatidylinositol 4,5-bisphosphate triggers activation of focal adhesion kinase by inducing clustering and conformational changes.

    PubMed

    Goñi, Guillermina M; Epifano, Carolina; Boskovic, Jasminka; Camacho-Artacho, Marta; Zhou, Jing; Bronowska, Agnieszka; Martín, M Teresa; Eck, Michael J; Kremer, Leonor; Gräter, Frauke; Gervasio, Francesco Luigi; Perez-Moreno, Mirna; Lietha, Daniel

    2014-08-01

    Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase (NRTK) with key roles in integrating growth and cell matrix adhesion signals, and FAK is a major driver of invasion and metastasis in cancer. Cell adhesion via integrin receptors is well known to trigger FAK signaling, and many of the players involved are known; however, mechanistically, FAK activation is not understood. Here, using a multidisciplinary approach, including biochemical, biophysical, structural, computational, and cell biology approaches, we provide a detailed view of a multistep activation mechanism of FAK initiated by phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]. Interestingly, the mechanism differs from canonical NRTK activation and is tailored to the dual catalytic and scaffolding function of FAK. We find PI(4,5)P2 induces clustering of FAK on the lipid bilayer by binding a basic region in the regulatory 4.1, ezrin, radixin, moesin homology (FERM) domain. In these clusters, PI(4,5)P2 induces a partially open FAK conformation where the autophosphorylation site is exposed, facilitating efficient autophosphorylation and subsequent Src recruitment. However, PI(4,5)P2 does not release autoinhibitory interactions; rather, Src phosphorylation of the activation loop in FAK results in release of the FERM/kinase tether and full catalytic activation. We propose that PI(4,5)P2 and its generation in focal adhesions by the enzyme phosphatidylinositol 4-phosphate 5-kinase type Iγ are important in linking integrin signaling to FAK activation. PMID:25049397

  4. Phosphatidylinositol 4,5-bisphosphate triggers activation of focal adhesion kinase by inducing clustering and conformational changes

    PubMed Central

    Goñi, Guillermina M.; Epifano, Carolina; Boskovic, Jasminka; Camacho-Artacho, Marta; Zhou, Jing; Bronowska, Agnieszka; Martín, M. Teresa; Eck, Michael J.; Kremer, Leonor; Gräter, Frauke; Gervasio, Francesco Luigi; Perez-Moreno, Mirna; Lietha, Daniel

    2014-01-01

    Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase (NRTK) with key roles in integrating growth and cell matrix adhesion signals, and FAK is a major driver of invasion and metastasis in cancer. Cell adhesion via integrin receptors is well known to trigger FAK signaling, and many of the players involved are known; however, mechanistically, FAK activation is not understood. Here, using a multidisciplinary approach, including biochemical, biophysical, structural, computational, and cell biology approaches, we provide a detailed view of a multistep activation mechanism of FAK initiated by phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2]. Interestingly, the mechanism differs from canonical NRTK activation and is tailored to the dual catalytic and scaffolding function of FAK. We find PI(4,5)P2 induces clustering of FAK on the lipid bilayer by binding a basic region in the regulatory 4.1, ezrin, radixin, moesin homology (FERM) domain. In these clusters, PI(4,5)P2 induces a partially open FAK conformation where the autophosphorylation site is exposed, facilitating efficient autophosphorylation and subsequent Src recruitment. However, PI(4,5)P2 does not release autoinhibitory interactions; rather, Src phosphorylation of the activation loop in FAK results in release of the FERM/kinase tether and full catalytic activation. We propose that PI(4,5)P2 and its generation in focal adhesions by the enzyme phosphatidylinositol 4-phosphate 5-kinase type Iγ are important in linking integrin signaling to FAK activation. PMID:25049397

  5. Destabilization of a Solar Prominence/Filament Field System by a Series of Eight Homologous Eruptive Flares Leading to a CME

    NASA Astrophysics Data System (ADS)

    Panesar, Navdeep K.; Sterling, Alphonse C.; Innes, Davina E.; Moore, Ronald L.

    2015-09-01

    Homologous flares are flares that occur repetitively in the same active region, with similar structure and morphology. A series of at least eight homologous flares occurred in active region NOAA 11237 over 2011 June 16-17. A nearby prominence/filament was rooted in the active region, and situated near the bottom of a coronal cavity. The active region was on the southeast solar limb as seen from the Solar Dynamics Observatory/Atmospheric Imaging Assembly, and on the disk as viewed from the Solar TErrestrial RElations Observatory/EUVI-B. The dual perspective allows us to study in detail behavior of the prominence/filament material entrained in the magnetic field of the repeatedly erupting system. Each of the eruptions were mainly confined, but expelled hot material into the prominence/filament cavity system (PFCS). The field carrying and containing the ejected hot material interacted with the PFCS and caused it to inflate, resulting in a step-wise rise of the PFCS approximately in step with the homologous eruptions. The eighth eruption triggered the PFCS to move outward slowly, accompanied by a weak coronal dimming. As this slow PFCS eruption was underway, a final “ejective” flare occurred in the core of the active region, resulting in strong dimming in the EUVI-B images and expulsion of a coronal mass ejection (CME). A plausible scenario is that the repeated homologous flares could have gradually destabilized the PFCS, and its subsequent eruption removed field above the acitive region and in turn led to the ejective flare, strong dimming, and CME.

  6. Near infrared emission from molecule-like silver clusters confined in zeolite A assisted by thermal activation

    SciTech Connect

    Lin, Hui Imakita, Kenji; Rong Gui, Sa Chu; Fujii, Minoru

    2014-07-07

    Strong and broad near infrared (NIR) emission peaked at ~855 nm upon optimal excitation at 342 nm has been observed from molecule-like silver clusters (MLSCs) confined in zeolite A assisted by thermal activation. To the best of our knowledge, this is the first observation of NIR emission peaked at longer than 800 nm from MLSCs confined in solid matrices. The decay time of the NIR emission is over 10 μs, which indicates that it is a spin-forbidden transition. The ~855 nm NIR emission shows strong dependence on the silver loading concentration and the thermal activation temperature.

  7. Advancing Water and Water-Energy-Food Cluster Activities within Future Earth

    NASA Astrophysics Data System (ADS)

    Lawford, R. G.; Bhaduri, A.; Pahl-Wostl, C.

    2014-12-01

    In building its emerging program, Future Earth has encouraged former Earth System Science Partnership (ESSP) projects to redefine their objectives, priorities and problem approaches so they are aligned with those of Future Earth. These new projects will be characterized by more integrated applications of natural and social sciences as well as dialogue and science integrated across disciplinary boundaries to address a wide range of environmental and social issues. The Global Water System Project (GWSP) has had a heritage of integrating natural and social sciences, and recently started to also look at issues within the Water-Energy-Food (WEF) cluster using similar integrated approaches. As part of the growth of the scientific elements of this cluster, GWSP has approached Future Earth opportunities by addressing the sustainability for Water, Energy, and Food through integrated water information and improved governance.In this presentation the approaches being considered for promoting integration in both water and the WEF cluster will be discussed. In particular, potential contributions of Future Earth to research related to the use and management of water and to issues and science underpinning the W-E-F nexus deliberations will be identified. In both cases the increasing ability to utilize Earth observations and big data will advance this research agenda. In addition, the better understanding of the implications of governance structures in addressing these issues and the options for harmonizing the use of scientific knowledge and technological advances will be explored. For example, insights gained from water management studies undertaken within the GWSP are helping to focus plans for a "sustainable water futures" project and a WEF cluster within Future Earth. The potential role of the Sustainable Development Goals in bringing together the monitoring and science capabilities, and understanding of governance approaches, will be discussed as a framework for facilitating

  8. Plasma properties from the multi-wavelength analysis of the November 1st 2003 CME/shock event

    PubMed Central

    Benna, Carlo; Mancuso, Salvatore; Giordano, Silvio; Gioannini, Lorenzo

    2012-01-01

    The analysis of the spectral properties and dynamic evolution of a CME/shock event observed on November 1st 2003 in white-light by the LASCO coronagraph and in the ultraviolet by the UVCS instrument operating aboard SOHO, has been performed to compute the properties of some important plasma parameters in the middle corona below about 2R⊙. Simultaneous observations obtained with the MLSO/Mk4 white-light coronagraph, providing both the early evolution of the CME expansion in the corona and the pre-shock electron density profile along the CME front, were also used to study this event. By combining the above information with the analysis of the metric type II radio emission detected by ground-based radio spectrographs, we finally derive estimates of the values of the local Alfvén speed and magnetic field strength in the solar corona. PMID:25685432

  9. The Width of a Solar Coronal Mass Ejection and the Source of the Driving Magnetic Explosion: A Test of the Standard Scenario for CME Production

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.; Sterling, Alphonse C.; Suess, Steven T.

    2007-01-01

    We show that the strength (B(sub F1are)) 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 (Final Theta(sub CME)) of the CME in the outer corona and the final angular width (Theta(sub Flare)) of the flare arcade: B(sub Flare) approx. equals 1.4[(Final Theta(sub CME)/Theta(sub Flare)] (exp 2)G. We assume (1) the flux-rope plasmoid ejected from the flare site becomes the interior of the CME plasmoid; (2) in the outer corona (R > 2 (solar radius)) the CME is roughly a "spherical plasmoid with legs" shaped like a lightbulb; 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. One of these CMEs was an over-and-out CME, that is, in the outer corona the CME was laterally far offset from the flare-marked source of the driving magnetic explosion. In each event, the estimated source-region field strength is appropriate for the magnetic setting of the flare. This agreement (1) indicates that CMEs are propelled by the magnetic field of the CME plasmoid pushing against the surrounding magnetic field; (2) supports the magnetic-arch-blowout scenario for over-and-out CMEs; and (3) shows that a CME's final angular width in the outer corona can be estimated from the amount of magnetic flux covered by the source-region flare arcade.

  10. What can we learn about CME evolution from multi-point observations?

    NASA Astrophysics Data System (ADS)

    Nieves-Chinchilla, T.

    2013-05-01

    Knowing about Coronal mass ejections (CMEs) propagation is critical for developing a reliable Space Weather forecast capability. Multi-spacecraft observations of CME/ICMEs are critical sources of information about the CME initiation and evolution from the Sun throughout the heliosphere. However, these investigations have been undertaken from two, quite separate points of view; namely, remote sensing and in-situ observations. In the recent years, there have been multiple efforts to provide a unique interpretation using remote and in-situ observations, mainly because of the availability of heliospheric imaging. However, a comprehensive and coordinated analysis of the multi-view point data, using different techniques and models, is still far of being completely understood. In this presentation, we will review the advances obtained thus far and demonstrate the discrepancies still larking between these two points of view using a thorough analysis of imaging and in-situ observations at many inner heliospheric locations. We use a combination of remote (SOHO, STEREO, SDO) and in-situ (Wind, ACE, MESSENGER) observations to show the potential of this approach to shed light into the dynamical interaction of CMEs with the solar wind during their propagation and development through the interplanetary medium.

  11. Solar Source and CME Properties of Solar Cycle 23 Ground Level Enhancement Events

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Nat; Xie, H.; Yashiro, S.; Akiyama, S.; Makela, P.; Usoskin, I.

    2010-01-01

    Solar cycle 23 witnessed the most complete set of observations of coronal mass ejections (CMEs) associated with the Ground Level Enhancement (GLE) events. GLE events are extreme cases of solar energetic particle (SEP) events in that the energetic particles penetrate Earth's neutral atmosphere to be detected by neutron monitors. In this paper we present the CME and their source properties that seem to be equally extreme. These observations are consistent with the idea that the GLE particles are accelerated in the same way as the regular SEP events by CME-driven shocks. While we cannot rule out the possibility of the presence of a flare component during GLE events, we can definitely say that a shock component is present in all the GLE events. We provide additional information on the GLE-associated type II radio bursts, complex type III radio bursts, and soft X-ray flares, which are not very different from those associated with large SEP events. Finally we compare the properties of GLEassociated CMEs in cycle 23 with those in cycle 22.

  12. PROPAGATION AND EVOLUTION OF THE JUNE 1st 2008 CME IN THE INTERPLANETARY MEDIUM

    NASA Astrophysics Data System (ADS)

    Nieves-Chinchilla, T.; Lamb, D. A.; Davila, J. M.; Vinas, A. F.; Moestl, C.; Hidalgo, M. A.; Farrugia, C. J.; Malandraki, O.; Dresing, N.; Gómez-Herrero, R.

    2009-12-01

    In this work we present a study of the coronal mass ejection (CME) of June 1st of 2008 in the interplanetary medium. This event has been extensively studied by others because of its favorable geometry and the possible consequences of its peculiar initiation for space weather forecasting. We show an analysis of the evolution of the CME in the interplanetary medium in order to shed some light on the propagation mechanism of the ICME. We have determined the typical shock associated characteristics of the ICME in order to understand the propagation properties. Using two different non force-free models of the magnetic cloud allows us to incorporate expansion of the cloud. We use in-situ measurements from STEREO B/IMPACT to characterize the ICME. In addition, we use images from STEREO A/SECCHI-HI to analyze the propagation and visual evolution of the associated flux rope in the interplanetary medium. We compare and contrast these observations with the results of the analytical models.

  13. The Divergence of CME and Sunspot Number Rates During Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Webb, David F.; St. Cyr, Orville Chris; Xie, Hong; Kuchar, Thomas Andrew

    2014-06-01

    In the previous three solar cycles the frequency of occurrence of CMEs observed in white light has closely tracked the solar cycle in both phase and amplitude, varying by an order of magnitude over the cycle. LASCO has now observed the entire solar Cycle 23 and continues to observe through the current rise and maximum phases of Cycle 24. Cycle 23 had an unusually long decline and extended minimum. During this period we have been able to image and count CMEs in the heliosphere, and can determine rates from both LASCO and STEREO SECCHI (since 2007) coronagraphs and from the Solar Mass Ejection Imager (SMEI - since 2003) and the SECCHI Heliospheric Imagers in the heliosphere. Manual rates estimated by observers are now supplemented by counts from identifications made by automatic programs, such as contained in the SEEDS, CACTus and ARTEMIS catalogs. Since the cycle 23/24 minimum, the CME and sunspot number rates have diverged, with similar cycle 23/24 rise and peak CME rates but much lower SSN rates in this cycle. We will discuss these rate estimates and their implications for the evolution of the global solar magnetic field.

  14. Kinetic Reconnection Simulations for CME Initiation Driven by Velocity-Shear

    NASA Astrophysics Data System (ADS)

    Black, C.; Antiochos, S. K.; Karpen, J.; DeVore, C. R.; Germaschewski, K.

    2012-12-01

    In the standard model for coronal mass ejections (CME) and/or solar flares, the free energy for the event resides in the strongly sheared magnetic field of a filament channel. The pre-eruption force balance consists of an upward force due to the magnetic pressure of the sheared field balanced by a downward tension due to overlying unsheared field. Magnetic reconnection is widely believed to be the mechanism that disrupts this force balance, leading to explosive eruption. For understanding CME/flare initiation, therefore, it is critical to model the onset or reconnection that is driven by the buildup of magnetic shear. In MHD simulations, the application of a magnetic field shear is a trivial matter. However, kinetic effects are important in the diffusion region and thus, it is important to examine this process with PIC simulations as well. The implementation of such a driver in PIC methods is nontrivial. The field must be sheared self-consistently/ indirectly to prevent the generation of waves that destroy the desired system. In the work presented here, we discuss methods for applying a velocity shear perpendicular to the plane of reconnection for a nonperiodic system. We also discuss the implementation of boundary conditions that are open to electric currents that flow through the system boundary. C.B. is supported through an appointment to the NASA Postdoctoral Program at GSFC, administered by Oak Ridge Associated Universities through a contract with NASA.

  15. Geomagnetic Field Variation during CME Events at High Latitude in European Zone

    NASA Astrophysics Data System (ADS)

    Chandel, Babita

    Geomagnetic Field Variation during CME Events at High Latitude in European Zone Babita Chandel, Shailendra Saini ,Sneha Yadav and A.K.Gwal Space Science Laboratory, Department of Physics, Barkatullah University, Bhopal-462026, India Abstract: The concerning results, are the variation of Geomagnetic Field Component in European Zone during CME events. The geomagnetic events selected for this study occurred during 2003-2006, a period of declining phase of solar cycle 23rd at European zone (Tromso, Sodankyla and Rorvik with Geomagnetic Latitude 69.39o N and Long. 18.56o E, Geomagnetic Latitude 67.360o N and Long. 26.363o E and Geomagnetic Latitude 64.56o N and Long.10.59 o E). From this study it is observed that the strength of a geomagnetic storm depends on the interplanetary-magnetospheric coupling parameter VBz. Higher the value of VBz, higher will be the strength of geomagnetic storm. Magnitude of variation at Rorvik is more as compared to Tromso and magnitude of variation is more at Tromso as compared to Sodankyla. Variation in vertical component is less as compared to the north-south and east-west component. Geomagnetic field components shows the variation when either interplanetary magnetic field orientes southward or remains southward for few hours.

  16. Ion acceleration at CME-driven shocks near the Earth and the Sun

    SciTech Connect

    Desai, Mihir; Dayeh, Maher; Ebert, Robert; Smith, Charles; Mason, Glenn; Li, G.

    2012-11-20

    We compare the behavior of heavy ion spectra during an Energetic Storm Particle (ESP) event that exhibited clear evidence of wave excitation with that observed during an intense, large gradual Solar Energetic Particle (SEP) event in which the associated <0.2 MeV/nucleon ions are delayed >12 hr. We interpret that the ESP event is an example of the first-order Fermi acceleration process where enhancements in the magnetic field power spectral densities around local ion cyclotron frequency {nu}{sub pc} indicate the presence of Alfven waves excited by accelerated protons streaming away from the in-situ interplanetary shock. The softening or unfolding of the CNO energy spectrum below {approx}200 keV/nucleon and the systematic organization of the Fe and O spectral roll-overs with the E/q ratio during the ESP event are likely due to M/Q-dependent trapping and scattering of the heavy ions by the proton-excited waves. Based on striking similarities in the spectral behavior observed upstream of both, the ESP and the SEP event, we suggest that coupling between proton-generated Alfven waves and energetic ions is also operating at the distant CME shock during the large, gradual SEP event, thereby providing us with a new, powerful tool to remotely probe the roles of shock geometries and wave-particle interactions at near-Sun CME-driven shocks.

  17. Small-group CME using e-mail discussions. Can it work?

    PubMed Central

    Marshall, J. N.; Stewart, M.; Ostbye, T.

    2001-01-01

    PROBLEM BEING ADDRESSED: Traditional continuing medical education (CME) approaches do not work well in changing physicians' behaviour, but some promising strategies and technologies might help. Our program sought to meld small-group learning with an Internet e-mail approach. OBJECTIVE OF PROGRAM: In 1994, the Family medicine Education and Research Network (FERN) was developed to support on-line discussion among London, Ont, and area family physicians. To support educational, moderated case discussions using e-mail, FERN Dissemination (FERN-D) was introduced to a subgroup of participants. We hoped to increase awareness and use of evidence-based research in clinical practice and to increase use of Internet-based resources for CME. The target group was family physicians in the London area. MAIN COMPONENTS OF PROGRAM: Forty volunteers were recruited and were e-mailed one case every 2 weeks; 34 completed the study. Each case was followed by further postings and, at the end of 2 weeks, by a summary of the group's discussion. Background material for each case was researched and was evidence-based. Evaluation was conducted using preintervention and postintervention mailed surveys combined with an e-mail feedback questionnaire and a modified focus group. CONCLUSION: On-line case-based discussion is a promising strategy for encouraging family physicians to access current research. More research is needed to determine whether it can be effectively used to change physicians' practice. PMID:11281090

  18. The Geo-Effectiveness of CME-Driven Shocks and Sheaths

    NASA Astrophysics Data System (ADS)

    Lugaz, Noé; Al-haddad, Nada; Schwadron, Nathan; Riley, Pete; Farrugia, Charles; Winslow, Reka

    2016-07-01

    Past studies have found that ˜30% of intense geomagnetic storms and ˜20% of moderate geomagnetic storms are caused by forward fast magnetosonic shocks and the sheath plasma and magnetic field behind these shocks, making shocks the second most important cause of geomagnetic storms after magnetic ejecta. Since only about 20% of fast-mode shocks are followed by a moderate geomagnetic storm, it is important to understand which shock and upstream properties are most effective in creating optimal conditions for the development of geomagnetic storms. To do so, we identify all fast-mode forwards shocks (˜100), for which the sheath region resulted in a moderate or intense geomagnetic storm during solar cycles 23 and 24 (1997 - 2015). We find that about half such shocks are shocks propagating into a preceding CME or shocks propagating into the sheath region of a preceding shock. Overall, only a small fraction of shocks propagating through normal solar wind are geo-effective (less than 15%), whereas the majority of shocks propagating through a previous CME are geo-effective. We further discuss the conditions which can result in the formation of southward Bz in the sheath region behind a shock.

  19. Comparison of CME and CIR driven geomagnetic storms using the artificial neural network model

    NASA Astrophysics Data System (ADS)

    Revallo, Milos; Valach, Fridrich; Hejda, Pavel; Bochnicek, Josef

    2016-04-01

    A model of geomagnetic storms based on the method of artificial neural networks (ANN) combined with an analytical approach is presented in the paper. Unlike our previous studies, here we focus on medium and weak geomagnetic storms caused by coronal mass ejections (CMEs) and those caused by corotating interaction regions (CIRs). As the model input, the hourly solar wind parameters measured by the ACE satellite at the libration point L1 are used. The time series of the Dst index is obtained as the model output. The simulated Dst index series is compared with the corresponding observatory data. The resulting Dst index series are inspected and typical features of CME and CIR driven storms are isolated. The model reliabilty is assessed using the skill scores, namely the correlation coefficient CC and the prediction efficiency PE. The general observation is that in the case of medium and weak geomagnetic storms the model performance is worse than in the case of intense geomagnetic storms studied in our previous paper. Due to more complex Dst index record, the model response for CIR driven storms is worse than in the case of CME driven storms.

  20. Three dimensional numerical simulation of the April 2000 CME event with a magnetized plasma blob model

    NASA Astrophysics Data System (ADS)

    Shen, Fang

    A three-dimensional time-dependent, numerical magnetohydrodynamic (MHD) model, with the asynchronous and parallel time-marching method is used to investigate the propagation of coronal mass ejections (CMEs) in the nonhomogenous background solar wind flow. The solar wind background with a self-consistent source surface structures as initial-boundary conditions is first presented, from the source surface of 2.5 Rs to the Earth's orbit (215 Rs) and beyond. The CMEs are simulated by means of a very simple flux rope model: a high density and high velocity magnetized plasma blob is superposed on a background steady state solar wind model with an initial velocity and launch direction. The dynamical interaction of a CME with the background solar wind flow between 2.5 and 220 Rs is investigated. We have chosen the well-defined halo-CME event of 4-6 April 2000 as a test case. In this validation study, we find that this 3D MHD model, with the asynchronous and parallel time-marching method, the self-consistent source surface and the simple flux rope model, provides a relatively satisfactory comparison with the ACE spacecraft observations at L1 point.

  1. Tracking a CME from Cradle to Grave: A Multi-wavelength Analysis of the February 6-7, 1997 Event

    NASA Astrophysics Data System (ADS)

    Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Kosugi, T.; Hudson, H.; Nitta, N.; Thompson, B.; Gurman, J.; Plunkett, S.; Howard, R.; Burkepile, J.

    1997-05-01

    The partially earth-directed coronal mass ejection (CME) event of 1997 February 6-7 originated from the southwest quadrant of the sun. The CME accelerated from 170 km/s to about 830 km/s when it reached a distance of 25 solar radii. The CME was an arcade eruption followed by bright prominence core structures. The prominence core was tracked continuously from the solar surface to the interplanetary medium by combining data from the Nobeyama radioheliograph (microwaves), Mauna Loa Solar Observatory (He 10830 { Angstroms}), SOHO/EIT (EUV) and SOHO/LASCO (white light). The CME was accompanied by an arcade formation, fully observed by the YOHKOH/SXT (soft X-rays) and SOHO/EIT (EUV). The X-ray and EUV observations suggest that the reconnection proceeded from the northwest end to the southeast end of a filament channel. In the SOHO/EIT images, the the feet of the soft X-ray arcade were observed as EUV ribbons. The CME event also caused a medium sized geomagnetic storm: The hourly equatorial Dst values attained storm level during 18:00-19:00 UT on February 09. This means the disturbance took about 2.25 days to reach the Earth. The first signatures of an IP shock was a pressure jump in the WIND data around 13:00 UT on Feb 09, 1997 which lasted for about 14 hours, followed by flux rope signatures. This CME event confirms a number of ideas about CMEs: The three part structure (frontal bright arcade, dark cavity and prominence core), disappearing filament, elongated arcade formation, and terrestrial effects. We make use of the excellent data coverage from the solar surface to the Earth to address a number of issues regarding the origin and propagation of the geoeffective solar disturbances. We benefited from discussions at the first SOHO-Yohkoh Coordinated Data Analysis Workshop, held March 3-7, 1997, at Goddard Space Flight Center.

  2. An Application of the Stereoscopic Self-similar-Expansion Model to the Determination of CME-Driven Shock Parameters

    NASA Astrophysics Data System (ADS)

    Volpes, L.; Bothmer, V.

    2015-10-01

    We present an application of the stereoscopic self-similar-expansion model (SSSEM) to Solar Terrestrial Relations Observatory (STEREO)/ Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) observations of the CME on 3 April 2010 and its associated shock. The aim is to verify whether CME-driven shock parameters can be inferred from the analysis of j-maps. For this purpose, we used the SSSEM to derive the CME and the shock kinematics. Arrival times and speeds, inferred assuming either propagation at constant speed or with uniform deceleration, agree well with Advanced Composition Explorer (ACE) measurements. The shock standoff distance [Δ], the density compression [ρd/ρu], and the Mach number [M] were calculated by combining the results obtained for the CME and shock kinematics with models for the shock location. Their values were extrapolated to L1 and compared to in-situ data. The in-situ standoff distance was obtained from ACE solar-wind measurements, and the Mach number and compression ratio were provided by the interplanetary shock database of the Harvard-Smithsonian Center for Astrophysics. They are ρd/ρu =2.84 and M = 2.2. The best fit to observations was obtained when the SSSEM half-width λ= 40°, and the CME and shock propagate with uniform deceleration. In this case we found Δ= 23 R_{⊙}, ρd/ρu =2.61, and M = 2.93. The study shows that CME-driven shock parameters can be estimated from the analysis of time-elongation plots and can be used to predict their in-situ values.

  3. Future capabilities of CME polarimetric 3D reconstructions with the METIS instrument: A numerical test

    NASA Astrophysics Data System (ADS)

    Pagano, P.; Bemporad, A.; Mackay, D. H.

    2015-10-01

    Context. Understanding the 3D structure of coronal mass ejections (CMEs) is crucial for understanding the nature and origin of solar eruptions. However, owing to the optical thinness of the solar corona we can only observe the line of sight integrated emission. As a consequence the resulting projection effects hide the true 3D structure of CMEs. To derive information on the 3D structure of CMEs from white-light (total and polarized brightness) images, the polarization ratio technique is widely used. The soon-to-be-launched METIS coronagraph on board Solar Orbiter will use this technique to produce new polarimetric images. Aims: This work considers the application of the polarization ratio technique to synthetic CME observations from METIS. In particular we determine the accuracy at which the position of the centre of mass, direction and speed of propagation, and the column density of the CME can be determined along the line of sight. Methods: We perform a 3D MHD simulation of a flux rope ejection where a CME is produced. From the simulation we (i) synthesize the corresponding METIS white-light (total and polarized brightness) images and (ii) apply the polarization ratio technique to these synthesized images and compare the results with the known density distribution from the MHD simulation. In addition, we use recent results that consider how the position of a single blob of plasma is measured depending on its projected position in the plane of the sky. From this we can interpret the results of the polarization ratio technique and give an estimation of the error associated with derived parameters. Results: We find that the polarization ratio technique reproduces with high accuracy the position of the centre of mass along the line of sight. However, some errors are inherently associated with this determination. The polarization ratio technique also allows information to be derived on the real 3D direction of propagation of the CME. The determination of this is of

  4. On the interplanetary evolution of CME-driven shocks: a comparison between remote sensing observations and in-situ data

    NASA Astrophysics Data System (ADS)

    Volpes, Laura; Bothmer, Volker

    2015-08-01

    Fast coronal mass ejections (CMEs) are a prime driver of major space weather effects and strong geomagnetic storms. When the CME propagation speed is higher than the Alfvén speed a shock forms in front of the CME leading edge. CME-driven shocks are observed in in-situ data and, with the advent of increasingly sensitive imaging instruments, also in remote sensing observations in the form of bright fronts ahead of the CMEs.In this work we present the study of 4 Earth-directed CMEs which drove shocks detected in STEREO COR 2 and HI observations. For each event we identify the source region and the signatures of CME eruption such as waves, EUV dimmings, flare and prominence eruptions. The shock and CME interplanetary evolution is determined from COR2 and HI observations via an application of triangulation techniques. Furthermore, propagation speed and arrival times are inferred. The CME geometry is modelled in COR2 via the graduated cylindrical shell (GCS) model and the assumption on self-similar expansion is tested by expanding the flux rope to the HI1 field of view. A combination of these results with models for the shock location allows to infer the time evolution of the compression ratio ρd/ρu across the shock and of the upstream Mach number M at locations where no direct plasma measurements are available. These values, as well as the arrival time and speed, are compared to ACE in-situ measurements to validate the results. For the 03 April 2010 event, e.g., the values of the Mach number and the compression ratio extrapolated to the position of ACE are respectively 2.1 < ρd/ρu < 2.4 and 2.3 < M < 2.5, in good agreement with the in-situ values found in literature, ρd/ρu = 2.84 and M = 2.2. This study is carried out in conjunction to simulations of CME initiation. Combined results from observations and simulations allow to connect the interplanetary and near-Earth properties of CMEs to those of their source regions, and to the mechanisms of CME onset.

  5. 76 FR 72414 - Agency Information Collection Activities: Proposed Collection; Comment Request

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-23

    ..., overcome, or work around barriers to integration of EHC products into CME programming with selected... Directors--Semi-structured interviews will be conducted with the representative of each participating CME... activities as an avenue for disseminating EHC products. (3) Interviews with Faculty...

  6. MET18 Connects the Cytosolic Iron-Sulfur Cluster Assembly Pathway to Active DNA Demethylation in Arabidopsis

    PubMed Central

    Tang, Kai; Zhang, Huiming; Mangrauthia, Satendra K.; Lei, Mingguang; Hsu, Chuan-Chih; Hou, Yueh-Ju; Wang, Chunguo; Li, Yan; Tao, W. Andy; Zhu, Jian-Kang

    2015-01-01

    DNA demethylation mediated by the DNA glycosylase ROS1 helps determine genomic DNA methylation patterns and protects active genes from being silenced. However, little is known about the mechanism of regulation of ROS1 enzymatic activity. Using a forward genetic screen, we identified an anti-silencing (ASI) factor, ASI3, the dysfunction of which causes transgene promoter hyper-methylation and silencing. Map-based cloning identified ASI3 as MET18, a component of the cytosolic iron-sulfur cluster assembly (CIA) pathway. Mutation in MET18 leads to hyper-methylation at thousands of genomic loci, the majority of which overlap with hypermethylated loci identified in ros1 and ros1dml2dml3 mutants. Affinity purification followed by mass spectrometry indicated that ROS1 physically associates with MET18 and other CIA components. Yeast two-hybrid and split luciferase assays showed that ROS1 can directly interact with MET18 and another CIA component, AE7. Site-directed mutagenesis of ROS1 indicated that the conserved iron-sulfur motif is indispensable for ROS1 enzymatic activity. Our results suggest that ROS1-mediated active DNA demethylation requires MET18-dependent transfer of the iron-sulfur cluster, highlighting an important role of the CIA pathway in epigenetic regulation. PMID:26492035

  7. MET18 Connects the Cytosolic Iron-Sulfur Cluster Assembly Pathway to Active DNA Demethylation in Arabidopsis.

    PubMed

    Duan, Cheng-Guo; Wang, Xingang; Tang, Kai; Zhang, Huiming; Mangrauthia, Satendra K; Lei, Mingguang; Hsu, Chuan-Chih; Hou, Yueh-Ju; Wang, Chunguo; Li, Yan; Tao, W Andy; Zhu, Jian-Kang

    2015-10-01

    DNA demethylation mediated by the DNA glycosylase ROS1 helps determine genomic DNA methylation patterns and protects active genes from being silenced. However, little is known about the mechanism of regulation of ROS1 enzymatic activity. Using a forward genetic screen, we identified an anti-silencing (ASI) factor, ASI3, the dysfunction of which causes transgene promoter hyper-methylation and silencing. Map-based cloning identified ASI3 as MET18, a component of the cytosolic iron-sulfur cluster assembly (CIA) pathway. Mutation in MET18 leads to hyper-methylation at thousands of genomic loci, the majority of which overlap with hypermethylated loci identified in ros1 and ros1dml2dml3 mutants. Affinity purification followed by mass spectrometry indicated that ROS1 physically associates with MET18 and other CIA components. Yeast two-hybrid and split luciferase assays showed that ROS1 can directly interact with MET18 and another CIA component, AE7. Site-directed mutagenesis of ROS1 indicated that the conserved iron-sulfur motif is indispensable for ROS1 enzymatic activity. Our results suggest that ROS1-mediated active DNA demethylation requires MET18-dependent transfer of the iron-sulfur cluster, highlighting an important role of the CIA pathway in epigenetic regulation. PMID:26492035

  8. Clustering Analysis of OFFICER'S Behaviours in London Police Foot Patrol Activities

    NASA Astrophysics Data System (ADS)

    Shen, J.; Cheng, T.

    2015-07-01

    In this small paper we aim at presenting a framework of conceptual representation and clustering analysis of police officers' patrol pattern obtained from mining their raw movement trajectory data. This have been achieved by a model developed to accounts for the spatio-temporal dynamics human movements by incorporating both the behaviour features of the travellers and the semantic meaning of the environment they are moving in. Hence, the similarity metric of traveller behaviours is jointly defined according to the stay time allocation in each Spatio-temporal region of interests (ST-ROI) to support clustering analysis of patrol behaviours. The proposed framework enables the analysis of behaviour and preferences on higher level based on raw moment trajectories. The model is firstly applied to police patrol data provided by the Metropolitan Police and will be tested by other type of dataset afterwards.

  9. Growth of fluorescence gold clusters using photo-chemically activated ligands

    NASA Astrophysics Data System (ADS)

    Mishra, Dinesh; Aldeek, Fadi; Michael, Serge; Palui, Goutam; Mattoussi, Hedi

    2016-03-01

    Ligands made of lipoic acid (LA) appended with a polyethylene glycol (PEG) chain have been used in the aqueous phase growth of luminescent gold clusters with distinct emission from yellow to near-IR, using two different routes. In the first route, the gold-ligand complex was chemically reduced using sodium borohydride in alkaline medium, which gave near- IR luminescent gold clusters with maximum emission around 745 nm. In the second method, LA-PEG ligand was photochemically modified to a mixture of thiols, oligomers and oxygenated species under UV-irradiation, which was then used as both reducing agent and stabilizing ligand. By adjusting the pH, temperature, and time of the reaction, we were able to obtain clusters with two distinct emission properties. Refluxing the gold-ligand complex in alkaline medium in the presence of excess ligand gave yellow emission within the first two hours and the emission shifted to red after overnight reaction. Mass spectrometry and chemical assay were used to understand the photo-chemical transformation of Lipoic Acid (LA). Mass spectroscopic studies showed the photo-irradiated product contains thiols, oligomers (dimers, trimers and tetramers) as well as oxygenated species. The amount of thiol formed under different conditions of irradiation was estimated using Ellman's assay.

  10. The formation of the brightest cluster galaxies in cosmological simulations: the case for active galactic nucleus feedback

    NASA Astrophysics Data System (ADS)

    Martizzi, Davide; Teyssier, Romain; Moore, Ben

    2012-03-01

    We use 500 pc resolution cosmological simulations of a Virgo-like galaxy cluster to study the properties of the brightest cluster galaxy (BCG) that forms at the centre of the halo. We compared two simulations; one incorporating only supernova feedback and a second that also includes prescriptions for black hole growth and the resulting active galactic nucleus (AGN) feedback from gas accretion. As previous work has shown, with supernova feedback alone we are unable to reproduce any of the observed properties of massive cluster ellipticals. The resulting BCG rotates quickly, has a high Sérsic index, a strong mass excess in the centre and a total central density profile falling more steeply than isothermal. Furthermore, it is far too efficient at converting most of the available baryons into stars which is strongly constrained by abundance matching. With a treatment of black hole dynamics and AGN feedback the BCG properties are in good agreement with data: they rotate slowly, have a cored surface density profile, a flat or rising velocity dispersion profile and a low stellar mass fraction. The AGN provides a new mechanism to create cores in luminous elliptical galaxies; the core expands due to the combined effects of heating from dynamical friction of sinking massive black holes and AGN feedback that ejects gaseous material from the central regions.

  11. Two- and four-component relativistic generalized-active-space coupled cluster method: implementation and application to BiH.

    PubMed

    Sørensen, Lasse K; Olsen, Jeppe; Fleig, Timo

    2011-06-01

    A string-based coupled-cluster method of general excitation rank and with optimal scaling which accounts for special relativity within the four-component framework is presented. The method opens the way for the treatment of multi-reference problems through an active-space inspired single-reference based state-selective expansion of the model space. The evaluation of the coupled-cluster vector function is implemented by considering contractions of elementary second-quantized operators without setting up the amplitude equations explicitly. The capabilities of the new method are demonstrated in application to the electronic ground state of the bismuth monohydride molecule. In these calculations simulated multi-reference expansions with both doubles and triples excitations into the external space as well as the regular coupled-cluster hierarchy up to full quadruples excitations are compared. The importance of atomic outer core-correlation for obtaining accurate results is shown. Comparison to the non-relativistic framework is performed throughout to illustrate the additional work of the transition to the four-component relativistic framework both in implementation and application. Furthermore, an evaluation of the highest order scaling for general-order expansions is presented. PMID:21663339

  12. Visible light photocatalytic activity of rutile TiO2 fiber clusters in the degradation of terephthalic acid

    NASA Astrophysics Data System (ADS)

    Yener, H. Banu; Helvacı, Şerife Ş.

    2015-09-01

    Rutile TiO2 nanoparticles, in different structural and morphological properties, were produced by the hydrolysis of titanium tetrachloride in a highly acidic reaction media at moderate temperatures without calcination. Their photocatalytic activities were investigated in the liquid-phase degradation of terephthalic acid under visible light illumination. The parameters, which are the concentration of the titanium tetrachloride solution (0.1-1 M) and reaction temperature (60-95 °C), effective on the properties of the particles, and their photocatalytic performances, were investigated. The XRD patterns indicated a pure rutile crystal structure at moderate temperatures without need of calcination. The FEGSEM images showed the formation of flower-, pinecone-, and sphere-like clusters consisting of interconnected nanofibers. The N2 adsorption-desorption isotherms pointed out the microporous structure of the clusters. Band gap energies were found to be varying between 3.02 and 3.08 eV due to the well-developed rutile crystallite structure. Systematic studies elucidated that the optimum reactant concentration and reaction temperature are 0.5 M TiCl4 and 95 °C, respectively. The rutile clusters synthesized at the optimum reaction conditions exhibited 99 % of the photocatalytic degradation of TPA under visible light illumination at shorter irradiation times compared with commercial P25 TiO2.

  13. A Minimal Nitrogen Fixation Gene Cluster from Paenibacillus sp. WLY78 Enables Expression of Active Nitrogenase in Escherichia coli

    PubMed Central

    Zhao, Dehua; Liu, Xiaomeng; Zhang, Bo; Xie, Jianbo; Hong, Yuanyuan; Li, Pengfei; Chen, Sanfeng; Dixon, Ray; Li, Jilun

    2013-01-01

    Most biological nitrogen fixation is catalyzed by molybdenum-dependent nitrogenase, an enzyme complex comprising two component proteins that contains three different metalloclusters. Diazotrophs contain a common core of nitrogen fixation nif genes that encode the structural subunits of the enzyme and components required to synthesize the metalloclusters. However, the complement of nif genes required to enable diazotrophic growth varies significantly amongst nitrogen fixing bacteria and archaea. In this study, we identified a minimal nif gene cluster consisting of nine nif genes in the genome of Paenibacillus sp. WLY78, a gram-positive, facultative anaerobe isolated from the rhizosphere of bamboo. We demonstrate that the nif genes in this organism are organized as an operon comprising nifB, nifH, nifD, nifK, nifE, nifN, nifX, hesA and nifV and that the nif cluster is under the control of a σ70 (σA)-dependent promoter located upstream of nifB. To investigate genetic requirements for diazotrophy, we transferred the Paenibacillus nif cluster to Escherichia coli. The minimal nif gene cluster enables synthesis of catalytically active nitrogenase in this host, when expressed either from the native nifB promoter or from the T7 promoter. Deletion analysis indicates that in addition to the core nif genes, hesA plays an important role in nitrogen fixation and is responsive to the availability of molybdenum. Whereas nif transcription in Paenibacillus is regulated in response to nitrogen availability and by the external oxygen concentration, transcription from the nifB promoter is constitutive in E. coli, indicating that negative regulation of nif transcription is bypassed in the heterologous host. This study demonstrates the potential for engineering nitrogen fixation in a non-nitrogen fixing organism with a minimum set of nine nif genes. PMID:24146630

  14. A Cluster Of Activities On Coma From The Hubble Space Telescope, StarDate, And McDonald Observatory

    NASA Astrophysics Data System (ADS)

    Hemenway, Mary Kay; Jogee, S.; Fricke, K.; Preston, S.

    2011-01-01

    With a goal of providing a vast audience of students, teachers, the general public, and Spanish-speakers with activities to learn about research on the Coma cluster of galaxies based on the HST ACS Treasury survey of Coma, McDonald Observatory used a many-faceted approach. Since this research offered an unprecedented legacy dataset, part of the challenge was to convey the importance of this project to a diverse audience. The methodology was to create different products for different (overlapping) audiences. Five radio programs were produced in English and Spanish for distribution on over 500 radio stations in the US and Mexico with a listening audience of over 2 million; in addition to the radio listeners, there were over 13,000 downloads of the English scripts and almost 6000 of the Spanish. Images were prepared for use in the StarDate Online Astronomy Picture of the Week, for ViewSpace (used in museums), and for the StarDate/Universo Teacher Guide. A high-school level activity on the Coma Cluster was prepared and distributed both on-line and in an upgraded printed version of the StarDate/Universo Teacher Guide. This guide has been distributed to over 1700 teachers nationally. A YouTube video about careers and research in astronomy using the Coma cluster as an example was produced. Just as the activities were varied, so were the evaluation methods. This material is based upon work supported by the National Aeronautics and Space Administration under Grant/Contract/Agreement No. HST-EO-10861.35-A issued through the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  15. Large-conductance calcium-activated potassium channels in purkinje cell plasma membranes are clustered at sites of hypolemmal microdomains.

    PubMed

    Kaufmann, Walter A; Ferraguti, Francesco; Fukazawa, Yugo; Kasugai, Yu; Shigemoto, Ryuichi; Laake, Petter; Sexton, Joseph A; Ruth, Peter; Wietzorrek, Georg; Knaus, Hans-Günther; Storm, Johan F; Ottersen, Ole Petter

    2009-07-10

    Calcium-activated potassium channels have been shown to be critically involved in neuronal function, but an elucidation of their detailed roles awaits identification of the microdomains where they are located. This study was undertaken to unravel the precise subcellular distribution of the large-conductance calcium-activated potassium channels (called BK, KCa1.1, or Slo1) in the somatodendritic compartment of cerebellar Purkinje cells by means of postembedding immunogold cytochemistry and SDS-digested freeze-fracture replica labeling (SDS-FRL). We found BK channels to be unevenly distributed over the Purkinje cell plasma membrane. At distal dendritic compartments, BK channels were scattered over the plasma membrane of dendritic shafts and spines but absent from postsynaptic densities. At the soma and proximal dendrites, BK channels formed two distinct pools. One pool was scattered over the plasma membrane, whereas the other pool was clustered in plasma membrane domains overlying subsurface cisterns. The labeling density ratio of clustered to scattered channels was about 60:1, established in SDS-FRL. Subsurface cisterns, also called hypolemmal cisterns, are subcompartments of the endoplasmic reticulum likely representing calciosomes that unload and refill Ca2+ independently. Purkinje cell subsurface cisterns are enriched in inositol 1,4,5-triphosphate receptors that mediate the effects of several neurotransmitters, hormones, and growth factors by releasing Ca2+ into the cytosol, generating local Ca2+ sparks. Such increases in cytosolic [Ca2+] may be sufficient for BK channel activation. Clustered BK channels in the plasma membrane may thus participate in building a functional unit (plasmerosome) with the underlying calciosome that contributes significantly to local signaling in Purkinje cells. PMID:19412945

  16. IUE observations of rapidly rotating low-mass stars in young clusters - The relation between chromospheric activity and rotation

    NASA Technical Reports Server (NTRS)

    Simon, Theodore

    1990-01-01

    If the rapid spindown of low-mass stars immediately following their arrival on the ZAMS results from magnetic braking by coronal winds, an equally sharp decline in their chromospheric emission may be expected. To search for evidence of this effect, the IUE spacecraft was used to observe the chromospheric Mg II emission lines of G-M dwarfs in the nearby IC 2391, Alpha Persei, Pleiades, and Hyades clusters. Similar observations were made of a group of X-ray-selected 'naked' T Tauri stars in Taurus-Auriga. The existence of a decline in activity cannot be confirmed from the resulting data. However, the strength of the chromospheric emission in the Mg II lines of the cluster stars is found to be correlated with rotation rate, being strongest for the stars with the shortest rotation periods and weakest for those with the longest periods. This provides indirect support for such an evolutionary change in activity. Chromospheric activity may thus be only an implicit function of age.

  17. Acoustic Cluster Therapy: In Vitro and Ex Vivo Measurement of Activated Bubble Size Distribution and Temporal Dynamics.

    PubMed

    Healey, Andrew John; Sontum, Per Christian; Kvåle, Svein; Eriksen, Morten; Bendiksen, Ragnar; Tornes, Audun; Østensen, Jonny

    2016-05-01

    Acoustic cluster technology (ACT) is a two-component, microparticle formulation platform being developed for ultrasound-mediated drug delivery. Sonazoid microbubbles, which have a negative surface charge, are mixed with micron-sized perfluoromethylcyclopentane droplets stabilized with a positively charged surface membrane to form microbubble/microdroplet clusters. On exposure to ultrasound, the oil undergoes a phase change to the gaseous state, generating 20- to 40-μm ACT bubbles. An acoustic transmission technique is used to measure absorption and velocity dispersion of the ACT bubbles. An inversion technique computes bubble size population with temporal resolution of seconds. Bubble populations are measured both in vitro and in vivo after activation within the cardiac chambers of a dog model, with catheter-based flow through an extracorporeal measurement flow chamber. Volume-weighted mean diameter in arterial blood after activation in the left ventricle was 22 μm, with no bubbles >44 μm in diameter. After intravenous administration, 24.4% of the oil is activated in the cardiac chambers. PMID:26831341

  18. Analysis of HSC activity and compensatory Hox gene expression profile in Hoxb cluster mutant fetal liver cells.

    PubMed

    Bijl, Janet; Thompson, Alexander; Ramirez-Solis, Ramiro; Krosl, Jana; Grier, David G; Lawrence, H Jeffrey; Sauvageau, Guy

    2006-07-01

    Overexpression of Hoxb4 in bone marrow cells promotes expansion of hematopoietic stem cell (HSC) populations in vivo and in vitro, indicating that this homeoprotein can activate the genetic program that determines self-renewal. However, this function cannot be solely attributed to Hoxb4 because Hoxb4(-/-) mice are viable and have an apparently normal HSC number. Quantitative polymerase chain reaction analysis showed that Hoxb4(-/-) c-Kit+ fetal liver cells expressed moderately higher levels of several Hoxb cluster genes than control cells, raising the possibility that normal HSC activity in Hoxb4(-/-) mice is due to a compensatory up-regulation of other Hoxb genes. In this study, we investigated the competitive repopulation potential of HSCs lacking Hoxb4 alone, or in conjunction with 8 other Hoxb genes. Our results show that Hoxb4(-/-) and Hoxb1-b9 (-/-) fetal liver cells retain full competitive repopulation potential and the ability to regenerate all myeloid and lymphoid lineages. Quantitative Hox gene expression profiling in purified c-Kit+ Hoxb1-b9(-/-) fetal liver cells revealed an interaction between the Hoxa, b, and c clusters with variation in expression levels of Hoxa4,-a11, and -c4.Together, these studies show a complex network of genetic interactions between several Hox genes in primitive hematopoietic cells and demonstrate that HSCs lacking up to 30% of the active Hox genes remain fully competent. PMID:16339407

  19. The cytosolic Fe-S cluster assembly component MET18 is required for the full enzymatic activity of ROS1 in active DNA demethylation

    PubMed Central

    Wang, Xiaokang; Li, Qi; Yuan, Wei; Cao, Zhendong; Qi, Bei; Kumar, Suresh; Li, Yan; Qian, Weiqiang

    2016-01-01

    DNA methylation patterns in plants are dynamically regulated by DNA methylation and active DNA demethylation in response to both environmental changes and development of plant. Beginning with the removal of methylated cytosine by ROS1/DME family of 5-methylcytosine DNA glycosylases, active DNA demethylation in plants occurs through base excision repair. So far, many components involved in active DNA demethylation remain undiscovered. Through a forward genetic screening of Arabidopsis mutants showing DNA hypermethylation at the EPF2 promoter region, we identified the conserved iron-sulfur cluster assembly protein MET18. MET18 dysfunction caused DNA hypermethylation at more than 1000 loci as well as the silencing of reporter genes and some endogenous genes. MET18 can directly interact with ROS1 in vitro and in vivo. ROS1 activity was reduced in the met18 mutant plants and point mutation in the conserved Fe-S cluster binding motif of ROS1 disrupted its biological function. Interestingly, a large number of DNA hypomethylated loci, especially in the CHH context, were identified from the met18 mutants and most of the hypo-DMRs were from TE regions. Our results suggest that MET18 can regulate both active DNA demethylation and DNA methylation pathways in Arabidopsis. PMID:27193999

  20. The cytosolic Fe-S cluster assembly component MET18 is required for the full enzymatic activity of ROS1 in active DNA demethylation.

    PubMed

    Wang, Xiaokang; Li, Qi; Yuan, Wei; Cao, Zhendong; Qi, Bei; Kumar, Suresh; Li, Yan; Qian, Weiqiang

    2016-01-01

    DNA methylation patterns in plants are dynamically regulated by DNA methylation and active DNA demethylation in response to both environmental changes and development of plant. Beginning with the removal of methylated cytosine by ROS1/DME family of 5-methylcytosine DNA glycosylases, active DNA demethylation in plants occurs through base excision repair. So far, many components involved in active DNA demethylation remain undiscovered. Through a forward genetic screening of Arabidopsis mutants showing DNA hypermethylation at the EPF2 promoter region, we identified the conserved iron-sulfur cluster assembly protein MET18. MET18 dysfunction caused DNA hypermethylation at more than 1000 loci as well as the silencing of reporter genes and some endogenous genes. MET18 can directly interact with ROS1 in vitro and in vivo. ROS1 activity was reduced in the met18 mutant plants and point mutation in the conserved Fe-S cluster binding motif of ROS1 disrupted its biological function. Interestingly, a large number of DNA hypomethylated loci, especially in the CHH context, were identified from the met18 mutants and most of the hypo-DMRs were from TE regions. Our results suggest that MET18 can regulate both active DNA demethylation and DNA methylation pathways in Arabidopsis. PMID:27193999

  1. Activation and Products of the Cryptic Secondary Metabolite Biosynthetic Gene Clusters by Rifampin Resistance (rpoB) Mutations in Actinomycetes

    PubMed Central

    Tanaka, Yukinori; Kasahara, Ken; Hirose, Yutaka; Murakami, Kiriko; Kugimiya, Rie

    2013-01-01

    A subset of rifampin resistance (rpoB) mutations result in the overproduction of antibiotics in various actinomycetes, including Streptomyces, Saccharopolyspora, and Amycolatopsis, with H437Y and H437R rpoB mutations effective most frequently. Moreover, the rpoB mutations markedly activate (up to 70-fold at the transcriptional level) the cryptic/silent secondary metabolite biosynthetic gene clusters of these actinomycetes, which are not activated under general stressful conditions, with the exception of treatment with rare earth elements. Analysis of the metabolite profile demonstrated that the rpoB mutants produced many metabolites, which were not detected in the wild-type strains. This approach utilizing rifampin resistance mutations is characterized by its feasibility and potential scalability to high-throughput studies and would be useful to activate and to enhance the yields of metabolites for discovery and biochemical characterization. PMID:23603745

  2. The mechanism of emerging catalytic activity of gold nano-clusters on rutile TiO{sub 2}(110) in CO oxidation reaction

    SciTech Connect

    Mitsuhara, K.; Tagami, M.; Matsuda, T.; Visikovskiy, A.; Kido, Y.; Takizawa, M.

    2012-03-28

    This paper reveals the fact that the O adatoms (O{sub ad}) adsorbed on the 5-fold Ti rows of rutile TiO{sub 2}(110) react with CO to form CO{sub 2} at room temperature and the oxidation reaction is pronouncedly enhanced by Au nano-clusters deposited on the above O-rich TiO{sub 2}(110) surfaces. The optimum activity is obtained for 2D clusters with a lateral size of {approx}1.5 nm and two-atomic layer height corresponding to {approx}50 Au atoms/cluster. This strong activity emerging is attributed to an electronic charge transfer from Au clusters to O-rich TiO{sub 2}(110) supports observed clearly by work function measurement, which results in an interface dipole. The interface dipoles lower the potential barrier for dissociative O{sub 2} adsorption on the surface and also enhance the reaction of CO with the O{sub ad} atoms to form CO{sub 2} owing to the electric field of the interface dipoles, which generate an attractive force upon polar CO molecules and thus prolong the duration time on the Au nano-clusters. This electric field is screened by the valence electrons of Au clusters except near the perimeter interfaces, thereby the activity is diminished for three-dimensional clusters with a larger size.

  3. Does cluster-root activity benefit nutrient uptake and growth of co-existing species?

    PubMed

    Muler, Ana L; Oliveira, Rafael S; Lambers, Hans; Veneklaas, Erik J

    2014-01-01

    Species that inhabit phosphorus- (P) and micronutrient-impoverished soils typically have adaptations to enhance the acquisition of these nutrients, for example cluster roots in Proteaceae. However, there are several species co-occurring in the same environment that do not produce similar specialised roots. This study aims to investigate whether one of these species (Scholtzia involucrata) can benefit from the mobilisation of P or micronutrients by the cluster roots of co-occurring Banksia attenuata, and also to examine the response of B. attenuata to the presence of S. involucrata. We conducted a greenhouse experiment, using a replacement series design, where B. attenuata and S. involucrata shared a pot at proportions of 2:0, 1:2 and 0:4. S. involucrata plants grew more in length, were heavier and had higher manganese (Mn) concentrations in their young leaves when grown next to one individual of B. attenuata and one individual of S. involucrata than when grown with three conspecifics. All S. involucrata individuals were colonised by arbuscular mycorrhizal fungi, and possibly Rhizoctonia. Additionally, P concentration was higher in the young leaves of B. attenuata when grown with another B. attenuata than when grown with two individuals of S. involucrata, despite the smaller size of the S. involucrata individuals. Our results demonstrate that intraspecific competition was stronger than interspecific competition for S. involucrata, but not for B. attenuata. We conclude that cluster roots of B. attenuata facilitate the acquisition of nutrients by neighbouring shrubs by making P and Mn more available for their neighbours. PMID:23934064

  4. Active Tectonics of Southern California Revealed by Cluster Analysis of GPS Velocities

    NASA Astrophysics Data System (ADS)

    Thatcher, W. R.; Savage, J. C.; Simpson, R. W.

    2013-12-01

    We use cluster analysis of the USGS National Seismic Hazard Map GPS velocity field for southern California with standard deviations < 1 mm/yr to determine velocity gradients that locate the most important faults, the elastic strain associated with them, and regions of possible block-like behavior. Seven to ten well resolved clusters are statistically significant and spatially distinct with small overlap. In map view (see figure), the 7 clusters solution shows bands of relatively constant velocity sub-parallel to the San Andreas (SAF) and San Jacinto (SJF) faults and the major faults of the eastern Mojave shear zone (EMSZ). These bands are due both to elastic strain accumulation on the SAF and relative motion across lower slip rate faults in the EMSZ and Los Angeles and Ventura basins. At the largest scale, the 7-cluster map shows two main trends. The blue dots define the SJ and SA faults from northwest of the Salton Sea (SS) to Parkfield (P); the grey/magenta boundary suggests that the defined Eastern California Shear Zone could be extended farther south to the Salton Sea. The short ~80-km-long San Gorgonio Pass-San Bernardino Mountains (SGP) segment of the SAF has a much lower slip rate, ~7 mm/yr of right-lateral oblique convergence. As generally shown by previous GPS studies, right-lateral strike-slip movement rates vary considerably along the SAF. In the Imperial Valley (IV) the rate is ~40 mm/yr; east of the Salton Sea it drops to ~20 mm/yr, with 10-15 mm/yr having been shunted westward to the SJF; north of the Salton Sea ~10-15 mm/yr of strike-slip is transferred to the faults of the eastern Mojave; therefore the east-trending faults of San Gorgonio Pass (SGP) take up only ~5 mm/yr of strike slip and ~equal amounts of north-south shortening; on the Mojave (M) segment of the SAF the slip rate increases to ~15-20 mm/yr in the vicinity of Cajon Pass (CP) because of transfer of SJF slip back onto the San Andreas; northwest of Tejon Pass the rate increases again to

  5. Biorthogonal moment expansions in coupled-cluster theory: Review of key concepts and merging the renormalized and active-space coupled-cluster methods

    NASA Astrophysics Data System (ADS)

    Shen, Jun; Piecuch, Piotr

    2012-06-01

    After reviewing recent progress in the area of the development of coupled-cluster (CC) methods for quasi-degenerate electronic states that are characterized by stronger non-dynamical correlation effects, including new generations of single- and multi-reference approaches that can handle bond breaking and excited states dominated by many-electron transitions, and after discussing the key elements of the left-eigenstate completely renormalized (CR) CC and equation-of-motion (EOM) CC methods, and the underlying biorthogonal method of moments of CC (MMCC) equations [P. Piecuch, M. Włoch, J. Chem. Phys. 123 (2005) 224105; P. Piecuch, M. Włoch, J.R. Gour, A. Kinal, Chem. Phys. Lett. 418 (2006) 467; M. Włoch, M.D. Lodriguito, P. Piecuch, J.R. Gour, Mol. Phys. 104 (2006) 2149], it is argued that it is beneficial to merge the CR-CC/EOMCC and active-space CC/EOMCC [P. Piecuch, Mol. Phys. 108 (2010) 2987, and references therein] theories into a single formalism. In order to accomplish this goal, the biorthogonal MMCC theory, which provides compact many-body expansions for the differences between the full configuration interaction and CC or, in the case of excited states, EOMCC energies, obtained using conventional truncation schemes in the cluster operator T and excitation operator Rμ, is generalized, so that one can correct the CC/EOMCC energies obtained with arbitrary truncations in T and Rμ for the selected many-electron correlation effects of interest. The resulting moment expansions, defining the new, Flexible MMCC (Flex-MMCC) formalism, and the ensuing CC(P; Q) hierarchy, proposed in the present work, enable one to correct energies obtained in the active-space CC and EOMCC calculations, in which one selects higher many-body components of T and Rμ via active orbitals and which recover much of the relevant non-dynamical and some dynamical electron correlation effects in applications involving potential energy surfaces (PESs) along bond breaking coordinates, for the

  6. Relation Between the 3D-Geometry of the Coronal Wave and Associated CME During the 26 April 2008 Event

    NASA Technical Reports Server (NTRS)

    Temmer, M.; Veronig, A. M.; Gopalswamy, N.; Yashiro, S.

    2011-01-01

    We study the kinematical characteristics and 3D geometry of a large-scale coronal wave that occurred in association with the 26 April 2008 flare-CME event. The wave was observed with the EUVI instruments aboard both STEREO spacecraft (STEREO-A and STEREO-B) with a mean speed of approx 240 km/s. The wave is more pronounced in the eastern propagation direction, and is thus, better observable in STEREO-B images. From STEREO-B observations we derive two separate initiation centers for the wave, and their locations fit with the coronal dimming regions. Assuming a simple geometry of the wave we reconstruct its 3D nature from combined STEREO-A and STEREO-B observations. We find that the wave structure is asymmetric with an inclination toward East. The associated CME has a deprojected speed of approx 750 +/- 50 km/s, and it shows a non-radial outward motion toward the East with respect to the underlying source region location. Applying the forward fitting model developed by Thernisien, Howard, and Vourlidas we derive the CME flux rope position on the solar surface to be close to the dimming regions. We conclude that the expanding flanks of the CME most likely drive and shape the coronal wave.

  7. Gas dynamic modeling of the CME propagation through the envelope of a hot Jupiter-type exoplanet

    NASA Astrophysics Data System (ADS)

    Cherenkov, A. A.; Kaygorodov, P. V.; Bisikalo, D. V.

    2016-05-01

    We propose a 3D gasdynamic numerical model for the study of the interaction between the extended envelopes of hot Jupiters, overfilling their Roche lobes, and non-stationary stellar wind. In the model we use a Roe-Osher numerical scheme with Eindfeldt entropy fix. To test the model we have simulated a flow structure, forming due to the interaction between the extended quasi-stationary envelope of the hot Jupiter planet HD 209458b and the bow shock formed ahead of a propagating coronal mass ejection (CME). We have adopted the solar CME parameters in our computations and taken into account the fact that the planet is located close to its host star. The simulation results show that the bow shock of the CME partially destroys the stream, starting from the Li point of the quasi-closed planet's envelope. A bow shock, existing ahead of the planet in its orbital motion when the stellar wind is undisturbed, almost disappears when the CME shock passes through the system.

  8. C-ME: A 3D Community-Based, Real-Time Collaboration Tool for Scientific Research and Training

    PubMed Central

    Kolatkar, Anand; Kennedy, Kevin; Halabuk, Dan; Kunken, Josh; Marrinucci, Dena; Bethel, Kelly; Guzman, Rodney; Huckaby, Tim; Kuhn, Peter

    2008-01-01

    The need for effective collaboration tools is growing as multidisciplinary proteome-wide projects and distributed research teams become more common. The resulting data is often quite disparate, stored in separate locations, and not contextually related. Collaborative Molecular Modeling Environment (C-ME) is an interactive community-based collaboration system that allows researchers to organize information, visualize data on a two-dimensional (2-D) or three-dimensional (3-D) basis, and share and manage that information with collaborators in real time. C-ME stores the information in industry-standard databases that are immediately accessible by appropriate permission within the computer network directory service or anonymously across the internet through the C-ME application or through a web browser. The system addresses two important aspects of collaboration: context and information management. C-ME allows a researcher to use a 3-D atomic structure model or a 2-D image as a contextual basis on which to attach and share annotations to specific atoms or molecules or to specific regions of a 2-D image. These annotations provide additional information about the atomic structure or image data that can then be evaluated, amended or added to by other project members. PMID:18286178

  9. [Pathophysiology of cluster headache].

    PubMed

    Donnet, Anne

    2015-11-01

    The aetiology of cluster headache is partially unknown. Three areas are involved in the pathogenesis of cluster headache: the trigeminal nociceptive pathways, the autonomic system and the hypothalamus. The cluster headache attack involves activation of the trigeminal autonomic reflex. A dysfunction located in posterior hypothalamic gray matter is probably pivotal in the process. There is a probable association between smoke exposure, a possible genetic predisposition and the development of cluster headache. PMID:26470883

  10. Efficient active waveguiding properties of Mo6 nano-cluster-doped polymer nanotubes

    NASA Astrophysics Data System (ADS)

    Bigeon, J.; Huby, N.; Amela-Cortes, M.; Molard, Y.; Garreau, A.; Cordier, S.; Bêche, B.; Duvail, J.-L.

    2016-06-01

    We investigate 1D nanostructures based on a Mo6@SU8 hybrid nanocomposite in which photoluminescent Mo6 clusters are embedded in the photosensitive SU8 resist. Tens of micrometers long Mo6@SU8-based tubular nanostructures were fabricated by the wetting template method, enabling the control of the inner and outer diameter to about 190 nm and 240 nm respectively, as supported by structural and optical characterizations. The image plane optical study of these nanotubes under optical pumping highlights the efficient waveguiding phenomenon of the red luminescence emitted by the clusters. Moreover, the wave vector distribution in the Fourier plane determined by leakage radiation microscopy gives additional features of the emission and waveguiding. First, the anisotropic red luminescence of the whole system can be attributed to the guided mode along the nanotube. Then, a low-loss propagation behavior is evidenced in the Mo6@SU8-based nanotubes. This result contrasts with the weaker waveguiding signature in the case of UV210-based nanotubes embedding PFO (poly(9,9-di-n-octylfluorenyl-2,7-diyl)). It is attributed to the strong reabsorption phenomenon, owing to overlapping between absorption and emission bands in the semi-conducting conjugated polymer PFO. These results make this Mo6@SU8 original class of nanocomposite a promising candidate as nanosources for submicronic photonic integration.

  11. Efficient active waveguiding properties of Mo6 nano-cluster-doped polymer nanotubes.

    PubMed

    Bigeon, J; Huby, N; Amela-Cortes, M; Molard, Y; Garreau, A; Cordier, S; Bêche, B; Duvail, J-L

    2016-06-24

    We investigate 1D nanostructures based on a Mo6@SU8 hybrid nanocomposite in which photoluminescent Mo6 clusters are embedded in the photosensitive SU8 resist. Tens of micrometers long Mo6@SU8-based tubular nanostructures were fabricated by the wetting template method, enabling the control of the inner and outer diameter to about 190 nm and 240 nm respectively, as supported by structural and optical characterizations. The image plane optical study of these nanotubes under optical pumping highlights the efficient waveguiding phenomenon of the red luminescence emitted by the clusters. Moreover, the wave vector distribution in the Fourier plane determined by leakage radiation microscopy gives additional features of the emission and waveguiding. First, the anisotropic red luminescence of the whole system can be attributed to the guided mode along the nanotube. Then, a low-loss propagation behavior is evidenced in the Mo6@SU8-based nanotubes. This result contrasts with the weaker waveguiding signature in the case of UV210-based nanotubes embedding PFO (poly(9,9-di-n-octylfluorenyl-2,7-diyl)). It is attributed to the strong reabsorption phenomenon, owing to overlapping between absorption and emission bands in the semi-conducting conjugated polymer PFO. These results make this Mo6@SU8 original class of nanocomposite a promising candidate as nanosources for submicronic photonic integration. PMID:27171341

  12. Clustering Finnish Gambler Profiles Based on the Money and Time Consumed in Gambling Activities.

    PubMed

    Heiskanen, Maria; Toikka, Arho

    2016-06-01

    Gambling involves consumption of gamblers' money and time. Gamblers are a heterogeneous group, and in addition to grouping gamblers based on personality factors, it is also important to find different gambler profiles with respect to their gambling behavior. Using the nationally representative survey 'Finnish Gambling 2011' (N = 4484), this article studies the subtypes of Finnish gamblers based on the frequency of gambling and the amounts of money and time used in different gambling forms. Cluster analysis reveals six profiles of gamblers, from infrequent gamblers to omnivorous gamblers. In the further analysis of the clusters, it was found that the highest problem gambling prevalence was in the groups of sport betting + electronic gaming machine gamblers and omnivorous gamblers, which were also both dominated by men. Certain gambling consumption patterns and risk factors for problem gambling are related to both socio-demographic backgrounds of the gamblers as well as the structural and situational characteristics of the games. The results have implications for the prevention of problem gambling, as some consumption patterns may be connected with the probability of developing gambling problems. PMID:26026988

  13. Rhenium Complexes and Clusters Supported on c-Al2O3: Effects of Rhenium Oxidation State and Rhenium Cluster Size on Catalytic Activity for n-butane Hydrogenolysis

    SciTech Connect

    Lobo Lapidus, R.; Gates, B

    2009-01-01

    Supported metals prepared from H{sub 3}Re{sub 3}(CO){sub 12} on {gamma}-Al{sub 2}O{sub 3} were treated under conditions that led to various rhenium structures on the support and were tested as catalysts for n-butane conversion in the presence of H{sub 2} in a flow reactor at 533 K and 1 atm. After use, two samples were characterized by X-ray absorption edge positions of approximately 5.6 eV (relative to rhenium metal), indicating that the rhenium was cationic and essentially in the same average oxidation state in each. But the Re-Re coordination numbers found by extended X-ray absorption fine structure spectroscopy (2.2 and 5.1) show that the clusters in the two samples were significantly different in average nuclearity despite their indistinguishable rhenium oxidation states. Spectra of a third sample after catalysis indicate approximately Re{sub 3} clusters, on average, and an edge position of 4.5 eV. Thus, two samples contained clusters approximated as Re{sub 3} (on the basis of the Re-Re coordination number), on average, with different average rhenium oxidation states. The data allow resolution of the effects of rhenium oxidation state and cluster size, both of which affect the catalytic activity; larger clusters and a greater degree of reduction lead to increased activity.

  14. Comparison of CME radial velocities from a flux rope model and an ice cream cone model

    NASA Astrophysics Data System (ADS)

    Kim, T.; Moon, Y.; Na, H.

    2011-12-01

    Coronal Mass Ejections (CMEs) on the Sun are the largest energy release process in the solar system and act as the primary driver of geomagnetic storms and other space weather phenomena on the Earth. So it is very important to infer their directions, velocities and three-dimensional structures. In this study, we choose two different models to infer radial velocities of halo CMEs since 2008 : (1) an ice cream cone model by Xue et al (2005) using SOHO/LASCO data, (2) a flux rope model by Thernisien et al. (2009) using the STEREO/SECCHI data. In addition, we use another flux rope model in which the separation angle of flux rope is zero, which is morphologically similar to the ice cream cone model. The comparison shows that the CME radial velocities from among each model have very good correlations (R>0.9). We will extending this comparison to other partial CMEs observed by STEREO and SOHO.

  15. Intranodular clusters of activated cells with T follicular helper phenotype in nodular lymphocyte predominant Hodgkin lymphoma: a pilot study of 32 cases from Finland.

    PubMed

    Nathwani, Bharat N; Vornanen, Martine; Winkelmann, Ria; Kansal, Rina; Doering, Claudia; Hartmann, Sylvia; Hansmann, Martin L

    2013-09-01

    In nodular lymphocyte predominant Hodgkin lymphoma (NLPHL), little is known about the presence of intranodular clusters of cytologically activated lymphoid cells producing a moth-eaten pattern histologically. This pilot study of 32 NLPHL cases from Finland ascertained (1) the frequency of the intranodular clusters of activated lymphoid cells, (2) the immunophenotype of the activated cells, (3) the size and immunophenotype of the rosetting cells, and (4) the clinical significance of the activated cells. Histologically, intranodular clusters of activated cells produced a moth-eaten pattern in 100% (32 cases; subtle in 62.5%, overt in 37.5%). In immunostains, activated cells in subtle clusters (20 cases) were very difficult to identify. Twelve cases had overt clusters of activated cells, which were positive with CD3, CD4, PD1, CXCL13 (T follicular helper [T(FH)] phenotype), but rarely with Ki-67 and BCL2. Most activated rosetting cells had the same immunophenotype as the nonrosetting cells, except for CXCL13. Clinical presentation for all 32 Finnish patients was distinctive: 97% men, 97% with peripheral lymphadenopathy and 35.5% with stage III/IV disease. Only 22% relapsed; 97% were in remission. There was no significant clinical difference between cases with overt and subtle clusters. Intranodular activated TFH cells in NLPHL appeared to be nonproliferating and not long-living, and they were not associated with any adverse clinical outcome. Although most activated cells were TFH cells, it seemed that they were unable to increase the number of malignant cells. The pathogenetic role of the intranodular activated TFH and the small T cells in NLPHL needs further investigation. PMID:23684509

  16. Interrupted Eruption of Large Quiescent Filament Associated with a Halo CME

    NASA Astrophysics Data System (ADS)

    Gosain, S.; Filippov, Boris; Ajor Maurya, Ram; Chandra, Ramesh

    2016-04-01

    We analyze the observations of an eruptive quiescent filament associated with a halo Coronal Mass Ejection (CME). We use observations from the Atmospheric Imaging Assembly (AIA) instrument onboard the Solar Dynamics Observatory (SDO), Solar and Heliospheric Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO), and the Solar Terrestrial Relations Observatory (STEREO A/B) satellites. The filament exhibits a slow-rise phase followed by a gradual acceleration and then completely disappears. The filament could be traced in STEREO observations up to an altitude of about 1.44 {R}ȯ , where its rise speed reached ∼14 km s‑1 and disappeared completely at about 10:32 UT on 2011 October 21. The CME associated with the filament eruption and two bright ribbons in the chromosphere both appeared at about 01:30 UT on October 22, i.e., 15 hr after the filament eruption was seen in He ii 304 Å filtergrams. We show that this delay is abnormally large even if the slow rise speed and slow acceleration of the filament are taken into account. To understand the cause of this delay, we compute the decay index (n) of the overlying coronal magnetic field. The height distribution of the decay index, n, suggests that the zone of instability (n \\gt 1) at a lower altitude, 144–480 Mm, is followed by a zone of stability (n \\lt 1) between 540 and 660 Mm. We interpret the observed delay to be due to the presence of the latter zone, i.e., the zone of stability, which could provide a second quasi-equilibrium state to the filament until it finally erupts.

  17. Shock wave driven by CME evidenced by metric type II burst and EUV wave

    NASA Astrophysics Data System (ADS)

    Cunha-Silva, R. D.; Fernandes, F. C. R.; Selhorst, C. L.

    2015-12-01

    Solar type II radio bursts are produced by plasma oscillations in the solar corona as a result of shock waves. The relationship between type II bursts and coronal shocks is well evidenced by observations since the 1960s. However, the drivers of the shocks associated with type II events at metric wavelengths remain as a controversial issue among solar physicists. The flares and the coronal mass ejections (CMEs) are considered as potential drivers of these shocks. In this article, we present an analysis of a metric type II burst observed on May 17, 2013, using data provided by spectrometers from e-CALLISTO (extended-Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatories) and EUV images from the Extreme Ultraviolet Imager (EUVI), aboard the Solar Terrestrial Relations Observatory (STEREO). The event was associated with an M3.2 SXR flare and a halo CME. The EUV wave produced by the expansion of the CME was clear from the EUV images. The heights of the EUV wave fronts proved to be consistent with the heights of the radio source obtained with the 2-4 × Newkirk density model, which provided a clue to an oblique propagation of the type-II-emitting shock segment. The results for the magnetic field in the regions of the shock also revealed to be consistent with the heights of the radio source obtained using the 2-4 × Newkirk density model. Exponential fit on the intensity maxima of the harmonic emission provided a shock speed of ∼580-990 km s-1, consistent with the average speed of the associated EUV wave front of 626 km s-1.

  18. The Role of Short-Term Precursors in a Hybrid CME Forecast

    NASA Astrophysics Data System (ADS)

    Johnston, J. C.; Kuchar, T. A.; Webb, D. F.

    2010-12-01

    The AFRL Space Weather Forecasting Laboratory (SWFL) was established as a testbed for data, models and techniques used to forecast significant space weather events. Most space weather originates at the Sun with coronal mass ejections (CMEs) being a significant source. When CMEs strike the Earth, they can cause auroras, geomagnetic storms and other hazardous conditions that can adversely affect space and grounds systems and personnel. The longer the advance warning of these phenomena, the more effective and efficient can be the mitigating steps taken by the military and civilian communities. Warning periods between 72 and 120 hours are needed, based on the required lead times necessary for satellite and air tasking orders. However, the magnetic properties and other characteristics of CMEs vary greatly and CMEs travel at variable speeds, taking from one to four days to reach Earth. Often the most geoeffective CMEs travel the fastest and a strictly deterministic approach will not meet the advance warning requirements in these cases. To remedy this, forecasters and system designers must incorporate climatology, persistence, recurrence, and precursory indicators to break the 72 hour barrier. With the long operational record of SOHO and other Solar/Heliospheric instruments we have data to work with for climatology, and with the advent of the Solar Mass Ejection Imager and the STEREO spacecraft, tracking of CMEs has been demonstrated as practical. However, indicators and precursors, minutes to hours before a CME launches, are currently elusive. This talk examines what such precursors might be and how they would fit into a Hybrid CME forecast.

  19. Evaluation of Speakers at CME: Cosmecon 2006, An International Conference on Ageing and Anti-ageing

    PubMed Central

    Vijayashankar MR

    2008-01-01

    Aim: To determine what constitutes effective or ineffective lecturing in dermatological conferences and also the utility of a scientific programme for the dermatologists. Methods and Materials: Evaluation forms were circulated to delegates attending the Cosmecon conference on ageing and anti-ageing, held in July 2006 at Bangalore. Feedback from the delegates in the form of completed evaluation forms of individual speakers and each session of the 3-day conference Cosmecon (including the live workshop on aesthetic and surgical procedures) were studied. Comments were analysed with the help of a biostatistician to determine the positive and negative responses. Results: On day 1 of the conference, workshop included 14 procedures by different specialists and on the second and third days of the conference, there were a total of 10 sessions, with five on each day. Evaluation forms were handed out to 440 delegates on day 1 and 600 delegates on days 2 and 3. Fifty-five speakers were evaluated by an average 56 delegates out of 440 delegates on day 1 and 600 delegates on the second and third days. The delegate response to completing the evaluation form was poor. Only about 25% of the delegates completed the feedback forms. However, the feedback did give some insight to the scientific programme, on both positive and negative aspects. Most delegates stated that they benefited from the presentations. The main negative response was lack of opportunity to ask questions after a lecture. The main positive comment was that the time keeping in the conference was very good. Conclusion: The response of the delegates in providing feedback was poor. Efforts have to be made to educate and encourage delegates to complete the feedback forms. Systematic review of the speakers would provide information to design future CME programmes effectively and to incorporate improvements for effective lecturing and to avoid ineffective lectures. The CME evaluation can also help the organizers to provide

  20. Plasma Physical Parameters along CME-driven Shocks. II. Observation-Simulation Comparison

    NASA Astrophysics Data System (ADS)

    Bacchini, F.; Susino, R.; Bemporad, A.; Lapenta, G.

    2015-08-01

    In this work, we compare the spatial distribution of the plasma parameters along the 1999 June 11 coronal mass ejection (CME)-driven shock front with the results obtained from a CME-like event simulated with the FLIPMHD3D code, based on the FLIP-MHD particle-in-cell method. The observational data are retrieved from the combination of white-light coronagraphic data (for the upstream values) and the application of the Rankine-Hugoniot equations (for the downstream values). The comparison shows a higher compression ratio X and Alfvénic Mach number MA at the shock nose, and a stronger magnetic field deflection d toward the flanks, in agreement with observations. Then, we compare the spatial distribution of MA with the profiles obtained from the solutions of the shock adiabatic equation relating MA, X, and {θ }{Bn} (the angle between the upstream magnetic field and the shock front normal) for the special cases of parallel and perpendicular shock, and with a semi-empirical expression for a generically oblique shock. The semi-empirical curve approximates the actual values of MA very well, if the effects of a non-negligible shock thickness {δ }{sh} and plasma-to magnetic pressure ratio {β }u are taken into account throughout the computation. Moreover, the simulated shock turns out to be supercritical at the nose and sub-critical at the flanks. Finally, we develop a new one-dimensional Lagrangian ideal MHD method based on the GrAALE code, to simulate the ion-electron temperature decoupling due to the shock transit. Two models are used, a simple solar wind model and a variable-γ model. Both produce results in agreement with observations, the second one being capable of introducing the physics responsible for the additional electron heating due to secondary effects (collisions, Alfvén waves, etc.).

  1. Wavelet analysis of CME, X-ray flare, and sunspot series

    NASA Astrophysics Data System (ADS)

    Guedes, M. R. G.; Pereira, E. S.; Cecatto, J. R.

    2015-01-01

    Context. Coronal mass ejections (CMEs) and solar flares are the most energetic transient phenomena taking place at the Sun. Together they are principally responsible for disturbances in outer geospace. Coronal mass ejections and solar flares are believed to be correlated with the solar cycle, which is mainly characterized by sunspot numbers. Aims: Here, we search for pattern identification in CMEs, X-ray solar flares, and sunspot number time series using a new data mining process and a quantitative procedure to correlate these series. Methods: This new process consists of the combination of a decomposition method with the wavelet transform technique applied to the series ranging from 2000 until 2012. A simple moving average is used for the time-series decomposition as a high-pass filter. A continuous wavelet transform is applied to the series in sequence, which permits us to uncover signals previously masked by the original time series. We made use of the wavelet coherence to find some correlation between the data. Results: The results have shown the existence of periodic and intermittent signals in the CMEs, flares, and sunspot time series. For the CME and flare series, few and relatively short time intervals without any signal were observed. Signals with an intermittent character take place during some epochs of the maximum and descending phases of the solar cycle 23 and rising phase of solar cycle 24. A comparison among X-ray flares, sunspots, and CME time series shows a stronger relation between flare and CMEs, although during some short intervals (four-eight months) and in a relatively narrow band. Yet, in contrast we have obtained a fainter or even absent relation between the X-ray flares and sunspot number series as well as between the CMEs and sunspot number series.

  2. Active mammalian replication origins are associated with a high-density cluster of mCpG dinucleotides.

    PubMed Central

    Rein, T; Zorbas, H; DePamphilis, M L

    1997-01-01

    ori-beta is a well-characterized origin of bidirectional replication (OBR) located approximately 17 kb downstream of the dihydrofolate reductase gene in hamster cell chromosomes. The approximately 2-kb region of ori-beta that exhibits greatest replication initiation activity also contains 12 potential methylation sites in the form of CpG dinucleotides. To ascertain whether DNA methylation might play a role at mammalian replication origins, the methylation status of these sites was examined with bisulfite to chemically distinguish cytosine (C) from 5-methylcytosine (mC). All of the CpGs were methylated, and nine of them were located within 356 bp flanking the minimal OBR, creating a high-density cluster of mCpGs that was approximately 10 times greater than average for human DNA. However, the previously reported densely methylated island in which all cytosines were methylated regardless of their dinucleotide composition was not detected and appeared to be an experimental artifact. A second OBR, located at the 5' end of the RPS14 gene, exhibited a strikingly similar methylation pattern, and the organization of CpG dinucleotides at other mammalian origins revealed the potential for high-density CpG methylation. Moreover, analysis of bromodeoxyuridine-labeled nascent DNA confirmed that active replication origins were methylated. These results suggest that a high-density cluster of mCpG dinucleotides may play a role in either the establishment or the regulation of mammalian replication origins. PMID:8972222

  3. The Devon Active Villages Evaluation (DAVE) trial of a community-level physical activity intervention in rural south-west England: a stepped wedge cluster randomised controlled trial

    PubMed Central

    2014-01-01

    Background The majority of adults are not meeting the guidelines for physical activity despite activity being linked with numerous improvements to long-term health. In light of this, researchers have called for more community-level interventions. The main objective of the present study was to evaluate whether a community-level physical activity intervention increased the activity levels of rural communities. Methods 128 rural villages (clusters) were randomised to receive the intervention in one of four time periods between April 2011 and December 2012. The Devon Active Villages intervention provided villages with 12 weeks of physical activity opportunities for all age groups, including at least three different types of activities per village. Each village received an individually tailored intervention, incorporating a local needs-led approach. Support was provided for a further 12 months following the intervention. The evaluation study used a stepped wedge cluster randomised controlled trial design. All 128 villages were measured at each of five data collection periods using a postal survey. The primary outcome of interest was the proportion of adults reporting sufficient physical activity to meet internationally recognised guidelines. Minutes spent in moderate-and-vigorous activity per week was analysed as a secondary outcome. To compare between intervention and control modes, random effects linear regression and marginal logistic regression models were implemented for continuous and binary outcomes respectively. Results 10,412 adults (4693 intervention, 5719 control) completed the postal survey (response rate 32.2%). The intervention did not increase the odds of adults meeting the physical activity guideline (adjusted OR 1.02, 95% CI: 0.88 to 1.17; P = 0.80), although there was weak evidence of an increase in minutes of moderate-and-vigorous-intensity activity per week (adjusted mean difference = 171, 95% CI: -16 to 358; P = 0.07). The

  4. Analysis of EIT/LASCO Observations Using Available MHD Models: Investigation of CME Initiation Propagation and Geoeffectiveness

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2001-01-01

    The Sun's activity drives the variability of geospace (i.e., near-earth environment). Observations show that the ejection of plasma from the sun, called coronal mass ejections (CMEs), are the major cause of geomagnetic storms. This global-scale solar dynamical feature of coronal mass ejection was discovered almost three decades ago by the use of space-borne coronagraphs (OSO-7, Skylab/ATM and P78-1). Significant progress has been made in understanding the physical nature of the CMEs. Observations show that these global-scale CMEs have size in the order of a solar radius (approximately 6.7 x 10(exp 5) km) near the sun, and each event involves a mass of about 10(exp 15) g and an energy comparable to that of a large flare on the order of 10(exp 32) ergs. The radial propagation speeds of CMEs have a wide range from tens to thousands of kilometers per second. Thus, the transit time to near earth's environment [i.e., 1 AU (astronomical unit)] can be as fast as 40 hours to 100 hours. The typical transit time for geoeffective events is approximately 60-80 h. This paper consists of two parts: 1) A summary of the observed CMEs from Skylab to the present SOHO will be presented. Special attention will be made to SOHO/ LASCO/ EIT observations and their characteristics leading to a geoeffectiv a CME 2) The chronological development of theory and models to interpret the physical nature of this fascinating phenomenon will be reviewed. Finally, an example will be presented to illustrate the geoeffectiveness of the CMEs by using both observation and model.

  5. Predicting CME Ejecta and Sheath Front Arrival at L1 with a Data-constrained Physical Model

    NASA Astrophysics Data System (ADS)

    Hess, Phillip; Zhang, Jie

    2015-10-01

    We present a method for predicting the arrival of a coronal mass ejection (CME) flux rope in situ, as well as the sheath of solar wind plasma accumulated ahead of the driver. For faster CMEs, the front of this sheath will be a shock. The method is based upon geometrical separate measurement of the CME ejecta and sheath. These measurements are used to constrain a drag-based model, improved by including both a height dependence and accurate de-projected velocities. We also constrain the geometry of the model to determine the error introduced as a function of the deviation of the CME nose from the Sun-Earth line. The CME standoff-distance in the heliosphere fit is also calculated, fit, and combined with the ejecta model to determine sheath arrival. Combining these factors allows us to create predictions for both fronts at the L1 point and compare them against observations. We demonstrate an ability to predict the sheath arrival with an average error of under 3.5 hr, with an rms error of about 1.58 hr. For the ejecta the error is less than 1.5 hr, with an rms error within 0.76 hr. We also discuss the physical implications of our model for CME expansion and density evolution. We show the power of our method with ideal data and demonstrate the practical implications of having a permanent L5 observer with space weather forecasting capabilities, while also discussing the limitations of the method that will have to be addressed in order to create a real-time forecasting tool.

  6. Differences between the CME fronts tracked by an expert, an automated algorithm, and the Solar Stormwatch project

    NASA Astrophysics Data System (ADS)

    Barnard, L.; Scott, C. J.; Owens, M.; Lockwood, M.; Crothers, S. R.; Davies, J. A.; Harrison, R. A.

    2015-10-01

    Observations from the Heliospheric Imager (HI) instruments aboard the twin STEREO spacecraft have enabled the compilation of several catalogues of coronal mass ejections (CMEs), each characterizing the propagation of CMEs through the inner heliosphere. Three such catalogues are the Rutherford Appleton Laboratory (RAL)-HI event list, the Solar Stormwatch CME catalogue, and, presented here, the J-tracker catalogue. Each catalogue uses a different method to characterize the location of CME fronts in the HI images: manual identification by an expert, the statistical reduction of the manual identifications of many citizen scientists, and an automated algorithm. We provide a quantitative comparison of the differences between these catalogues and techniques, using 51 CMEs common to each catalogue. The time-elongation profiles of these CME fronts are compared, as are the estimates of the CME kinematics derived from application of three widely used single-spacecraft-fitting techniques. The J-tracker and RAL-HI profiles are most similar, while the Solar Stormwatch profiles display a small systematic offset. Evidence is presented that these differences arise because the RAL-HI and J-tracker profiles follow the sunward edge of CME density enhancements, while Solar Stormwatch profiles track closer to the antisunward (leading) edge. We demonstrate that the method used to produce the time-elongation profile typically introduces more variability into the kinematic estimates than differences between the various single-spacecraft-fitting techniques. This has implications for the repeatability and robustness of these types of analyses, arguably especially so in the context of space weather forecasting, where it could make the results strongly dependent on the methods used by the forecaster.

  7. Improvements on GPS Location Cluster Analysis for the Prediction of Large Carnivore Feeding Activities: Ground-Truth Detection Probability and Inclusion of Activity Sensor Measures

    PubMed Central

    Blecha, Kevin A.; Alldredge, Mat W.

    2015-01-01

    Animal space use studies using GPS collar technology are increasingly incorporating behavior based analysis of spatio-temporal data in order to expand inferences of resource use. GPS location cluster analysis is one such technique applied to large carnivores to identify the timing and location of feeding events. For logistical and financial reasons, researchers often implement predictive models for identifying these events. We present two separate improvements for predictive models that future practitioners can implement. Thus far, feeding prediction models have incorporated a small range of covariates, usually limited to spatio-temporal characteristics of the GPS data. Using GPS collared cougar (Puma concolor) we include activity sensor data as an additional covariate to increase prediction performance of feeding presence/absence. Integral to the predictive modeling of feeding events is a ground-truthing component, in which GPS location clusters are visited by human observers to confirm the presence or absence of feeding remains. Failing to account for sources of ground-truthing false-absences can bias the number of predicted feeding events to be low. Thus we account for some ground-truthing error sources directly in the model with covariates and when applying model predictions. Accounting for these errors resulted in a 10% increase in the number of clusters predicted to be feeding events. Using a double-observer design, we show that the ground-truthing false-absence rate is relatively low (4%) using a search delay of 2–60 days. Overall, we provide two separate improvements to the GPS cluster analysis techniques that can be expanded upon and implemented in future studies interested in identifying feeding behaviors of large carnivores. PMID:26398546

  8. CO2 Activation and Hydrogenation by PtHn (-) Cluster Anions.

    PubMed

    Zhang, Xinxing; Liu, Gaoxiang; Meiwes-Broer, Karl-Heinz; Ganteför, Gerd; Bowen, Kit

    2016-08-01

    Gas phase reactions between PtHn (-) cluster anions and CO2 were investigated by mass spectrometry, anion photoelectron spectroscopy, and computations. Two major products, PtCO2 H(-) and PtCO2 H3 (-) , were observed. The atomic connectivity in PtCO2 H(-) can be depicted as HPtCO2 (-) , where the platinum atom is bonded to a bent CO2 moiety on one side and a hydrogen atom on the other. The atomic connectivity of PtCO2 H3 (-) can be described as H2 Pt(HCO2 )(-) , where the platinum atom is bound to a formate moiety on one side and two hydrogen atoms on the other. Computational studies of the reaction pathway revealed that the hydrogenation of CO2 by PtH3 (-) is highly energetically favorable. PMID:27363532

  9. The Relationship Between CME Properties in the CDAW, CACTUS and SEEDS Catalogs and ?25 MeV Solar Proton Event Intensities

    NASA Astrophysics Data System (ADS)

    Richardson, I. G.; von Rosenvinge, T. T.; Cane, H. V.

    2013-12-01

    The existence of a correlation between the intensity of solar energetic proton (SEP) events and the speed of the associated coronal mass ejection near the Sun is well known, and is often interpreted as evidence for particle acceleration at CME-driven shocks. However, this correlation is far from perfect and might be improved by taking other parameters into consideration (e.g., CME width). In studies of cycle 23 SEP events, values of CME speed, width and other parameters were typically taken from the CDAWWeb LASCO CME catalog. This is compiled 'by hand' from examination of LASCO images by experienced observers. Other automated LASCO CME catalogs have now been developed, e.g., CACTUS (Royal Observatory of Belgium) and SEEDS (George Mason University), but the basic CME parameters do not always agree with those from the CDAWweb catalog since they are not determined in the same way. For example the 'CME speed' might be measured at a specific position angle against the plane of the sky in one catalog, or be the average of speeds taken along the CME front in another. Speeds may also be based on linear or higher order fits to the coronagraph images. There will also be projection effects in these plane of the sky speeds. Similarly, CME widths can vary between catalogs and are dependent on how they are defined. For example, the CDAW catalog lists any CME that surrounds the occulting disk as a 'halo' (360 deg. width) CME even though the CME may be highly-asymmetric and originate from a solar event far from central meridian. Another catalog may give a smaller width for the same CME. The problem of obtaining the 'true' CME width is especially acute for assessing the relationship between CME width and SEP properties when using the CDAW catalog since a significant fraction, if not the majority, of the CMEs associated with major SEP events are reported to be halo CMEs. In principle, observations of CMEs from the STEREO A and B spacecraft, launched in late 2006, might be used to

  10. Transferability study of CHO cell clustering assays for monitoring of pertussis toxin activity in acellular pertussis vaccines.

    PubMed

    Isbrucker, R; Daas, A; Wagner, L; Costanzo, A

    2016-01-01

    Current regulations for acellular pertussis (aP) vaccines require that they are tested for the presence of residual or reversion-derived pertussis toxin (PTx) activity using the mouse histamine sensitisation test (HIST). Although a CHO cell clustering assay can be used by manufacturers to verify if sufficient inactivation of the substance has occurred in-process, this assay cannot be used at present for the final product due to the presence of aluminium adjuvants which interfere with mammalian cell cultures. Recently, 2 modified CHO cell clustering assays which accommodate for the adjuvant effects have been proposed as alternatives to the HIST. These modified assays eliminate the adjuvant-induced cytotoxicity either through dilution of the vaccine (called the Direct Method) or by introducing a porous barrier between the adjuvant and the cells (the Indirect Method). Transferability and suitability of these methods for testing of products present on the European market were investigated during a collaborative study organised by the European Directorate for the Quality of Medicines & HealthCare (EDQM). Thirteen laboratories participated in this study which included 4 aP-containing vaccines spiked by addition of PTx. This study also assessed the transferability of a standardised CHO cell clustering assay protocol for use with non-adjuvanted PTx preparations. Results showed that the majority of laboratories were able to detect the PTx spike in all 4 vaccines at concentrations of 4 IU/mL or lower using the Indirect Method. This sensitivity is in the range of the theoretical sensitivity of the HIST. The Direct Method however did not show the expected results and would need additional development work. PMID:27506252

  11. Methane activation by cobalt cluster cations, Con+ (n=2-16): Reaction mechanisms and thermochemistry of cluster-CHx (x=0-3) complexes

    NASA Astrophysics Data System (ADS)

    Citir,