WorldWideScience

Sample records for flares initial comparison

  1. Comparison between Major Confined and Eruptive Flares

    Science.gov (United States)

    Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Dennis, B. R.

    2012-05-01

    Statistical studies have shown that a large fraction of major solar flares (42% M-class and 15% X-class) are not associated with coronal mass ejections (CMEs). The CME-less flares are confined flares as opposed to the eruptive flares associated with CMEs. Confined flares are certainly good particle accelerators as inferred from intense microwave, hard X-ray, and gamma-ray emissions. Note that a single acceleration mechanism operates in confined flares, whereas eruptive flares can have both flare-resident and shock accelerations (the shock acceleration is due to energetic CMEs). In this paper, we report on a statistical study of more than two dozen confined flares with soft X-ray flare size exceeding M5 in comparison with a control sample of eruptive flares with similar soft X-ray flare size. We compare the microwave and X-ray emission characteristics in the two populations; these emissions correspond to sunward energy flow. For a given X-ray flare size, the microwave flux is scattered over a wider range for the eruptive flares when compared to the confined flares. We also compare the metric and longer wavelength radio bursts between the two populations; these emissions correspond to the flow of nonthermal electrons away from the Sun. We find that almost all the confined flares lack metric radio bursts, suggesting that there is very little flow of energy into the interplanetary medium. On the other hand, there is high degree of association between eruptive flares and metric radio bursts. This suggests that in confined flares the accelerated electrons have no access to open magnetic field lines. Finally, we examined the association of EUV waves with the two flare populations. While we find EUV waves in most of the eruptive flares, there was no confined flare with EUV waves. This suggests that CMEs is a necessary condition for the generation of global waves.

  2. Detection of Acceleration Processes During the Initial Phase of the 12 June 2010 Flare

    Science.gov (United States)

    Kashapova, L. K.; Meshalkina, N. S.; Kisil, M. S.

    2012-10-01

    We present an analysis of the plasma parameters during the initial phase of the 12 June 2010 flare (SOL2010-06-12T00:57). A peculiarity of the flare was the detection of γ-ray emission that is unusual for such weak and short event. The analysis revealed the presence of a flare precursor detected about five minutes before the flare onset in 94 Å images which spatially coincided with the non-polarized microwave (MW) source at 17 GHz (the Nobeyama Radio Heliograph) that is the Neutral Line associated Source (NLS). A comparison of the results obtained from MW data by the Nobeyama Radio Polarimeters and the multi-frequency Siberian Radioheliograph (the new 10-antenna radio heliograph prototype at 4.6 and 6.4 GHz) and hard X-ray (HXR) observations by the Fermi Gamma-ray Space Telescope reveal the presence of accelerated electrons during the flare's initial phase. The analysis of MW and HXR spectra also confirms the presence of accelerated particles. Moreover, a good temporal correlation between several light curves in different HXR energy bands and at MW frequencies indicates the generation of both HXR and MW emission by a common population of accelerated electrons. Detection of accelerated particles during the initial phase of the flare and soft-hard-harder (SHH) behavior of the spectra indicate several episodes of particle acceleration and confirm the non-impulsive type of the flare evolution.

  3. Type II Shocks Characteristics: Comparison with associated CMEs and Flares

    CERN Document Server

    Pothitakis, G; Preka-Papadema, P; Moussas, X; Caroubalos, C; Alissandrakis, C E; Hillaris, A; Tsitsipis, P; Kontogeorgos, A; Bougeret, J -L; Dumas, G; 10.1063/1.2347985

    2010-01-01

    A number of metric (100-650 MHz) typeII bursts was recorded by the ARTEMIS-IV radiospectrograph in the 1998-2000 period; the sample includes both CME driven shocks and shocks originating from flare blasts. We study their characteristics in comparison with characteristics of associated CMEs and flares.

  4. Detection of acceleration processes during the initial phase of the 12 June 2010 flare

    CERN Document Server

    Kashapova, L K; Kisil, M S

    2012-01-01

    We present an analysis of the plasma parameters during the initial phase of the 12 June 2010 flare (SOL2010-06-12T00:57). A peculiarity of the flare was the detection of $\\gamma$--emission that is unusual for such weak and short event. The analysis revealed the presence of a flare precursor detected about 5 minutes before the flare onset in 94 \\AA \\ images which spatially coincided with the non-polarized microwave (MW) source at 17 GHz (\\textit{the Nobeyama Radio Heliograph}) that is the Neutral Line associated Source (NLS). A comparison of the results obtained from MW data by \\textit{the Nobeyama Radio Polarimeters} and \\textit{the multi-frequency Siberian radioheliograph} (the new 10-antenna radio heliograph prototype at 4.6 and 6.4 GHz) and hard X-ray (HXR) observations by \\textit{the Fermi Gamma-ray Space Telescope} reveal the presence of accelerated electrons during the flare initial phase. The analysis of MW and HXR spectra also confirms the presence of accelerated particles. Moreover a good temporal co...

  5. A comparison between magnetic shear and flare shear in a well-observed M-class flare

    Institute of Scientific and Technical Information of China (English)

    Tuan-Hui Zhou; Hai-Sheng Ji

    2009-01-01

    We give an extensive multi-wavelength analysis of an eruptive M1.0/1N class solar flare, which occurred in the active region NOAA 10044 on 2002 July 26. Our empha-sis is on the relationship between magnetic shear and flare shear. Flare shear is defined as the angle formed between the line connecting the centroids of the two ribbons of the flare and the line perpendicular to the magnetic neutral line. The magnetic shear is computed from vector magnetograms observed at Big Bear Solar Observatory (BBSO), while the flare shear is computed from Transition Region and Coronal Explorer (TRACE) 1700A images. By a detailed comparison, we find that: 1) The magnetic shear and the flare shear of this event are basically consistent, as judged from the directions of the transverse mag-netic field and the line connecting the two ribbons' centroids. 2) During the period of the enhancement of magnetic shear, flare shear had a fast increase followed by a fluctuated decrease. 3) When the magnetic shear stopped its enhancement, the fluctuated decreasing behavior of the flare shear became very smooth. 4) Hard X-ray (HXR) spikes are well correlated with the unshearing peaks on the time profile of the rate of change of the flare shear. We give a discussion of the above phenomena.

  6. COMPLEX FLARE DYNAMICS INITIATED BY A FILAMENT–FILAMENT INTERACTION

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Chunming; McAteer, R. T. James [Department of Astronomy, New Mexico State University, NM 88003 (United States); Liu, Rui [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026 (China); Alexander, David [Department of Physics and Astronomy, Rice University, TX 77005 (United States); Sun, Xudong, E-mail: czhu@nmsu.edu [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)

    2015-11-01

    We report on an eruption involving a relatively rare filament–filament interaction on 2013 June 21, observed by SDO and STEREO-B. The two filaments were separated in height with a “double-decker” configuration. The eruption of the lower filament began simultaneously with a descent of the upper filament, resulting in a convergence and direct interaction of the two filaments. The interaction was accompanied by the heating of surrounding plasma and an apparent crossing of a loop-like structure through the upper filament. The subsequent coalescence of the filaments drove a bright front ahead of the erupting structures. The whole process was associated with a C3.0 flare followed immediately by an M2.9 flare. Shrinking loops and descending dark voids were observed during the M2.9 flare at different locations above a C-shaped flare arcade as part of the energy release, giving us unique insight into the flare dynamics.

  7. Prediction and comparison of noise levels from ground and elevated flare systems

    Energy Technology Data Exchange (ETDEWEB)

    Obasi, E. [Stantec Consulting Ltd., Surrey, BC (Canada)

    2009-07-01

    Flaring is a process to dispose of hydrocarbons during clean-up, emergency shut downs or dispose a small volume waste streams of mixed gasses that cannot easily or safely be separated. This presentation discussed flaring as a noise issue. It focused on flaring noise characterization; flare noise modeling; flare sound power levels; and flare sound pressure level comparison at a distance of 1.5 km. The presentation included a photograph of flaring at a gas plant in Nigeria. The presentation listed some of the potential health effects associated with long term exposure to excessive noise, such as hearing loss; headaches; stress; fatigue; sleep disturbance; and high blood pressure. Companies flare gas to dispose waste gases in a safe and reliable manner through combustion and to depressurize gas lines during maintenance and emergencies. This presentation also discussed ground and elevated flares; components of flare noise characterization; and key factors affecting flare noise. A model to predict flaring noise was also presented. It demonstrated that at the same gas mass flow rate, the noise level from elevated flare stacks are significantly higher than ground flares. tabs., figs.

  8. Initiation Processes for the 2013 May 13 X1.7 Limb Flare

    Science.gov (United States)

    Shen, Jinhua; Wang, Ya; Zhou, Tuanhui; Ji, Haisheng

    2017-01-01

    For the X1.7 class flare on 2013 May 13 (SOL2013-05-13T01:53), its initiation process was well observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory and the Extreme UltraViolet Imager (EUVI) on board STEREO-B. The initiation process incorporates the following phenomena: an X-ray precursor that started ∼9 minutes before flare onset, two hot magnetic loops (as seen with AIA hot channels) forming a sigmoidal core magnetic structure (as seen with the EUVI), a rapidly formed magnetic flux rope (MFR) that expands outward, and a flare loop that contracts inward. The two hot magnetic loops were activated after the occurrence of the X-ray precursor. After activation, magnetic reconnection occurred between the two hot magnetic loops (inside the sigmoid structure), which produced the expanding MFR and the contracting flare loop (CFL). The MFR and CFL can only be seen with AIA hot and cool channels, respectively. For this flare, the real initiation time can be regarded as being from the starting time of the precursor, and its impulsive phase started when the MFR began its fast expansion. In addition, the CFL and the growing postflare magnetic loops are different loop systems, and the CFL was the product of magnetic reconnection between sheared magnetic fields that also produced the MFR.

  9. Comparison of emission properties of two homologous flares in AR 11283

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yan; Jing, Ju; Wang, Shuo; Wang, Haimin, E-mail: yx2@njit.edu [Space Weather Research Lab, Center for Solar-Terrestrial Research, New Jersey Institute of Technology 323 Martin Luther King Boulevard, Newark, NJ 07102-1982 (United States)

    2014-05-20

    Large, complex, active regions may produce multiple flares within a certain period of one or two days. These flares could occur in the same location with similar morphologies, commonly referred to as 'homologous flares'. In 2011 September, active region NOAA 11283 produced a pair of homologous flares on the 6th and 7th, respectively. Both of them were white-light (WL) flares, as captured by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory in visible continuum at 6173 Å which is believed to originate from the deep solar atmosphere. We investigate the WL emission of these X-class flares with HMI's seeing-free imaging spectroscopy. The durations of impulsive peaks in the continuum are about 4 minutes. We compare the WL with hard X-ray (HXR) observations for the September 6 flare and find a good correlation between the continuum and HXR both spatially and temporally. In absence of RHESSI data during the second flare on September 7, the derivative of the GOES soft X-ray is used and also found to be well correlated temporally with the continuum. We measure the contrast enhancements, characteristic sizes, and HXR fluxes of the twin flares, which are similar for both flares, indicating analogous triggering and heating processes. However, the September 7 flare was associated with conspicuous sunquake signals whereas no seismic wave was detected during the flare on September 6. Therefore, this comparison suggests that the particle bombardment may not play a dominant role in producing the sunquake events studied in this paper.

  10. Prophylaxis for acute gout flares after initiation of urate-lowering therapy.

    Science.gov (United States)

    Latourte, Augustin; Bardin, Thomas; Richette, Pascal

    2014-11-01

    This review summarizes evidence relating to prophylaxis for gout flares after the initiation of urate-lowering therapy (ULT). We searched MEDLINE via PubMed for articles published in English from 1963 to 2013 using MEsH terms covering all aspects of prophylaxis for flares. Dispersion of monosodium urate crystals during the initial phase of deposit dissolution with ULT exposes the patient to an increased rate of acute flares that could contribute to poor treatment adherence. Slow titration of ULT might decrease the risk of flares. According to the most recent international recommendation, the two first-line options for prophylaxis are low-dose colchicine (0.5 mg once or twice a day) or low-dose NSAIDs such as naproxen 250 mg orally twice a day. They can be given for up to 6 months. If these drugs are contraindicated, not tolerated or ineffective, low-dose corticosteroids (prednisone or prednisolone) might be used. Recently, reports for four trials described the efficacy of canakinumab and rilonacept, two IL-1 inhibitors, for preventing flares during the initiation of allopurinol therapy. Prophylaxis for flares induced by ULT is an important consideration in gout management. Low-dose colchicine and low-dose NSAIDs are the recommended first-line therapies. Although no IL-1 blockers are approved as prophylactic treatment, this class of drug could become an interesting option for patients with gout with intolerance or contraindication to colchicine, NSAIDs or corticosteroids. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Prophylaxis on gout flares after the initiation of urate-lowering therapy: a retrospective research

    Science.gov (United States)

    Feng, Xin; Li, Yao; Gao, Wei

    2015-01-01

    The objective of this study was to evaluate the efficacy and safety associated with treatment available to prevent an acute attack of gout when initiating a urate-lowering therapy (ULT). We retrospectively reviewed patients who were diagnosed with gout and treated with ULT during the period from January 2000 to January 2014. They were divided into three groups, 75 patients without prophylaxis treatment, 103 patients treated with etoricoxib, and 129 patients with colchicine treatment. Both demographic and clinical characteristics associated with gout were analyzed. At baseline, demographic and clinical characteristics were generally similar in three groups. SU target level was achieved in 49.3% of the patients without prophylaxis treatment, 66.4% in the etoricoxib group and 65.1% in colchicine group, respectively. During the first 16 weeks, patients without prophylaxis treatment exhibited higher flare rates than patients in other two groups. However, no statistically significant difference was observed between patients in etoricoxib group and colchicine group. In the 16-24 weeks, the proportion of patients who reported flares were all decreased similarly in three groups. The mean number of acute gout flares per patient and gout flare days per patient was significantly higher in patients without prophylaxis treatment than patients in other groups. The mean number of acute gout flares was lower (4.2±2.3 vs 3.2±1.8) in patients with etoricoxib treatment than that in patients with colchicine treatment. Gout flare days per patient were significantly higher in patients without prophylaxis treatment. Compared to colchicine group, gout flare days per patient in etoricoxib were lower (1.2±0.5 vs 2.6±0.6). In term of AEs, patients receiving colchicine had higher rates of gastrointestinal AEs than those who received etoricoxib. In summary, our survey revealed that etoricoxib was more effective and safe than colchicine in preventing acute attack during ULT. PMID:26885092

  12. Spatial & Temporal Characteristics of Ha flares during the period 1975-2002 (comparison with SXR flares)

    CERN Document Server

    Gini, E; Hillaris, A; Preka-Papadema, P; Moussas, X; 10.1063/1.2347977

    2010-01-01

    Although the energetic phenomena of the Sun (flares, coronal mass injections etc.) exhibit intermittent stochastic behavior in their rate of occurrence, they are well correlated to the variations of the solar cycle. In this work we study the spatial and temporal characteristics of transient solar activity in an attempt to statistically interpret the evolution of these phenomena through the solar cycle, in terms of the self-organized criticality theory.

  13. A Comparison of Flare Forecasting Methods. I. Results from the “All-Clear” Workshop

    Science.gov (United States)

    Barnes, G.; Leka, K. D.; Schrijver, C. J.; Colak, T.; Qahwaji, R.; Ashamari, O. W.; Yuan, Y.; Zhang, J.; McAteer, R. T. J.; Bloomfield, D. S.; Higgins, P. A.; Gallagher, P. T.; Falconer, D. A.; Georgoulis, M. K.; Wheatland, M. S.; Balch, C.; Dunn, T.; Wagner, E. L.

    2016-10-01

    Solar flares produce radiation that can have an almost immediate effect on the near-Earth environment, making it crucial to forecast flares in order to mitigate their negative effects. The number of published approaches to flare forecasting using photospheric magnetic field observations has proliferated, with varying claims about how well each works. Because of the different analysis techniques and data sets used, it is essentially impossible to compare the results from the literature. This problem is exacerbated by the low event rates of large solar flares. The challenges of forecasting rare events have long been recognized in the meteorology community, but have yet to be fully acknowledged by the space weather community. During the interagency workshop on “all clear” forecasts held in Boulder, CO in 2009, the performance of a number of existing algorithms was compared on common data sets, specifically line-of-sight magnetic field and continuum intensity images from the Michelson Doppler Imager, with consistent definitions of what constitutes an event. We demonstrate the importance of making such systematic comparisons, and of using standard verification statistics to determine what constitutes a good prediction scheme. When a comparison was made in this fashion, no one method clearly outperformed all others, which may in part be due to the strong correlations among the parameters used by different methods to characterize an active region. For M-class flares and above, the set of methods tends toward a weakly positive skill score (as measured with several distinct metrics), with no participating method proving substantially better than climatological forecasts.

  14. Solar Flare Chromospheric Line Emission: Comparison Between IBIS High-resolution Observations and Radiative Hydrodynamic Simulations

    CERN Document Server

    da Costa, Fatima Rubio; Petrosian, Vahé; Dalda, Alberto Sainz; Liu, Wei

    2014-01-01

    Solar flares involve impulsive energy release, which results in enhanced radiation in a broad spectral and at a wide height range. In particular, line emission from the chromosphere (lower atmosphere) can provide critical diagnostics of plasma heating processes. Thus, a direct comparison between high-resolution spectroscopic observations and advanced numerical modeling results can be extremely valuable, but has not been attempted so far. We present in this paper such a self-consistent investigation of an M3.0 flare observed by the Dunn Solar Telescope's (DST) Interferometric Bi-dimensional Spectrometer (IBIS) on 2011 September 24 that we have modeled with the radiative hydrodynamic code RADYN (Carlsson & Stein 1992, 1997; Abbett & Hawley 1999; Allred et al. 2005). We obtained images and spectra of the flaring region with IBIS in H$\\alpha$ 6563 \\AA\\ and Ca II 8542 \\AA, and with the Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) in X-rays. The latter was used to infer the non-thermal elect...

  15. The Second NWRA Flare-Forecasting Comparison Workshop: Methods Compared and Methodology

    Science.gov (United States)

    Leka, K. D.; Barnes, G.; the Flare Forecasting Comparison Group

    2013-07-01

    The Second NWRA Workshop to compare methods of solar flare forecasting was held 2-4 April 2013 in Boulder, CO. This is a follow-on to the First NWRA Workshop on Flare Forecasting Comparison, also known as the ``All-Clear Forecasting Workshop'', held in 2009 jointly with NASA/SRAG and NOAA/SWPC. For this most recent workshop, many researchers who are active in the field participated, and diverse methods were represented in terms of both the characterization of the Sun and the statistical approaches used to create a forecast. A standard dataset was created for this investigation, using data from the Solar Dynamics Observatory/ Helioseismic and Magnetic Imager (SDO/HMI) vector magnetic field HARP series. For each HARP on each day, 6 hours of data were used, allowing for nominal time-series analysis to be included in the forecasts. We present here a summary of the forecasting methods that participated and the standardized dataset that was used. Funding for the workshop and the data analysis was provided by NASA/Living with a Star contract NNH09CE72C and NASA/Guest Investigator contract NNH12CG10C.

  16. Initiation of CME and Associated Flare Caused by Helical Kink Instability Observed by SDO/AIA

    CERN Document Server

    Kumar, Pankaj; Bong, S -C; Park, Sung-Hong; Kim, Y H

    2011-01-01

    In this paper, we present multiwavelength observations of helical kink instability as a trigger of a CME which occurred in AR NOAA 11163 on 24 February 2011. The CME was associated with a M3.5 limb flare. High resolution observations from SDO/AIA suggest the development of helical kink instability in the erupting prominence, which implies a flux rope structure of the magnetic field. A brightening starts below the apex of the prominence with its slow rising motion (~100 km/s) during the activation phase. A bright structure, indicative of a helix with ~3-4 turns, was transiently formed at this position. The corresponding twist of ~$6\\pi-8\\pi$ is sufficient to generate the helical kink instability in a flux rope according to recently developed models. A slowly rising blob structure was subsequently formed at the apex of the prominence, and a flaring loop was observed near the footpoints. Within two minutes, a second blob was formed in the northern prominence leg. The second blob erupts (like a plasmoid ejection)...

  17. Comparison of Emission Properties of two Homologous Flares in AR 11283

    CERN Document Server

    Xu, Yan; Wang, Shuo; Wang, Haimin

    2014-01-01

    Large, complex, active regions may produce multiple flares within a certain period of one or two days. These flares could occur in the same location with similar morphologies, commonly referred to as homologous flares. In 2011 September, active region NOAA 11283 produced a pair of homologous flares on the 6th and 7th, respectively. Both of them were white-light (WL) flares, as captured by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory in visible continuum at 617.3 nm which is believed to originate from the deep solar atmosphere.We investigate the WL emission of these X-class flares with HMIs seeing-free imaging spectroscopy. The durations of impulsive peaks in the continuum are about 4 minutes. We compare the WL with hard X-ray (HXR) observations for the September 6 flare and find a good correlation between the continuum and HXR both spatially and temporally. In absence of RHESSI data during the second flare on September 7, the derivative of the GOES soft X-ray is used and a...

  18. Responsibility of a Filament Eruption for the Initiation of a Flare, CME, and Blast Wave, and its Possible Transformation into a Bow Shock

    CERN Document Server

    Grechnev, V V; Kuzmenko, I V; Kochanov, A A; Chertok, I M; Kalashnikov, S S

    2014-01-01

    Multi-instrument observations of two filament eruptions on 24 February and 11 May 2011 suggest the following updated scenario for eruptive flare, CME and shock wave evolution. An initial destabilization of a filament results in stretching out of magnetic threads belonging to its body and rooted in the photosphere along the inversion line. Their reconnection leads to i) heating of parts of the filament or its environment, ii) initial development of the flare arcade cusp and ribbons, and iii) increasing similarity of the filament to a curved flux rope and its acceleration. Then the pre-eruption arcade enveloping the filament gets involved in reconnection according to the standard model and continues to form the flare arcade and ribbons. The poloidal magnetic flux in the curved rope developing from the filament progressively increases and forces its toroidal expansion. This flux rope impulsively expands and produces an MHD disturbance, which rapidly steepens into a shock. The shock passes through the arcade expa...

  19. Statistical Properties of Solar Flares and Comparison to Other Impulsive Energy Release Events

    Science.gov (United States)

    Lepreti, Fabio; Kossobokov, Vladimir G.; Carbone, Vincenzo

    Impulsive energy release events are observed in many natural systems. Solar flares are certainly among the most remarkable examples of such processes. In the last years the study of solar flare statistical properties has received considerable attention in the context of solar flare models based on different approaches, such as Self Organized Criticality (SOC) or magnetohydrodynamic (MHD) turbulence. In this talk the main statistical properties of solar flares will be presented and compared to those of other well known impulsive processes, such as earthquakes and soft γ-ray flashes occurring on neutron stars. It is shown that the these phenomena are characterized by different statistics that cannot be rescaled onto a single, universal curve and that this holds even for the same phenomenon, when observed in different periods or at different locations. Our results indicate apparent complexity of impulsive energy release processes, which neither follow a common behavior nor could be attributed to a universal physical mechanism.

  20. A Comparison of Flare Forecasting Methods, I: Results from the "All-Clear" Workshop

    CERN Document Server

    Barnes, G; Schrijver, C J; Colak, T; Qahwaji, R; Ashamari, O W; Yuan, Y; Zhang, J; McAteer, R T J; Bloomfield, D S; Higgins, P A; Gallagher, P T; Falconer, D A; Georgoulis, M K; Wheatland, M S; Balch, C; Dunn, T; Wagner, E L

    2016-01-01

    Solar flares produce radiation which can have an almost immediate effect on the near-Earth environment, making it crucial to forecast flares in order to mitigate their negative effects. The number of published approaches to flare forecasting using photospheric magnetic field observations has proliferated, with varying claims about how well each works. Because of the different analysis techniques and data sets used, it is essentially impossible to compare the results from the literature. This problem is exacerbated by the low event rates of large solar flares. The challenges of forecasting rare events have long been recognized in the meteorology community, but have yet to be fully acknowledged by the space weather community. During the interagency workshop on "all clear" forecasts held in Boulder, CO in 2009, the performance of a number of existing algorithms was compared on common data sets, specifically line-of-sight magnetic field and continuum intensity images from MDI, with consistent definitions of what ...

  1. Does the stellar distribution flare? A comparison of stellar scale heights with LAB H I data

    Energy Technology Data Exchange (ETDEWEB)

    Kalberla, P. M. W.; Kerp, J.; Dedes, L. [Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn (Germany); Haud, U., E-mail: pkalberla@astro.uni-bonn.de [Tartu Observatory, 61602 Tõravere (Estonia)

    2014-10-10

    The question of whether the stellar populations in the Milky Way take part in the flaring of scale heights as observed for the H I gas is a matter of debate. Standard mass models for the Milky Way assume a constant scale height for each of the different stellar distributions. However, there is mounting evidence that at least some of the stellar distributions reach, at large galactocentric distances, high altitudes, which are incompatible with a constant scale height. We discuss recent observational evidence for stellar flaring and compare it with H I data from the Leiden/Argentine/Bonn survey. Within the systemic and statistical uncertainties we find a good agreement between both.

  2. Does the Stellar Distribution Flare? A Comparison of Stellar Scale Heights with LAB H I Data

    Science.gov (United States)

    Kalberla, P. M. W.; Kerp, J.; Dedes, L.; Haud, U.

    2014-10-01

    The question of whether the stellar populations in the Milky Way take part in the flaring of scale heights as observed for the H I gas is a matter of debate. Standard mass models for the Milky Way assume a constant scale height for each of the different stellar distributions. However, there is mounting evidence that at least some of the stellar distributions reach, at large galactocentric distances, high altitudes, which are incompatible with a constant scale height. We discuss recent observational evidence for stellar flaring and compare it with H I data from the Leiden/Argentine/Bonn survey. Within the systemic and statistical uncertainties we find a good agreement between both.

  3. Does the stellar distribution flare? A comparison of stellar scale heights with LAB HI data

    CERN Document Server

    Kalberla, P M W; Dedes, L; Haud, U

    2014-01-01

    The question, whether the stellar populations in the Milky Way take part in flaring of the scale heights as observed for the HI gas is a matter of debate. Standard mass models for the Milky Way assume a constant scale height for each of the different stellar distributions. However, there is mounting evidence that at least some of the stellar distributions reach at large galactocentric distances high altitudes that are incompatible with a constant scale height. We discuss recent observational evidence for stellar flaring and compare it with HI data from the Leiden/Argentine/Bonn (LAB) survey. Within the systemic and statistical uncertainties we find a good agreement between both.

  4. Non-Maxwellian distribution functions in flaring coronal loops - Comparison of Landau-Fokker-Planck and BGK solutions

    Science.gov (United States)

    Ljepojevic, N. N.; Macneice, P.

    1988-01-01

    The high-velocity tail of the electron distribution has been calculated by solving the high-velocity form of the Landau equation for a thermal structure representative of a flaring coronal loop. These calculations show an enhancement of the tail population above Maxwellian for electrons moving down the temperature gradient. The results obtained are used to test the reliability of the BGK approximation. The comparison shows that the BGK technique can estimate contributions to the heat flux from the high-energy tail to within an order of magnitude.

  5. Comparison of Damped Oscillations in Solar and Stellar X-Ray flares

    Science.gov (United States)

    Cho, I.-H.; Cho, K.-S.; Nakariakov, V. M.; Kim, S.; Kumar, P.

    2016-10-01

    We explore the similarity and difference of the quasi-periodic pulsations (QPPs) observed in the decay phase of solar and stellar flares at X-rays. We identified 42 solar flares with pronounced QPPs, observed with RHESSI, and 36 stellar flares with QPPs, observed with XMM-Newton. The empirical mode decomposition (EMD) method and least-squares fit by a damped sine function were applied to obtain the periods (P) and damping times (τ) of the QPPs. We found that (1) the periods and damping times of the stellar QPPs are 16.21 ± 15.86 minutes and 27.21 ± 28.73 minutes, while those of the solar QPPs are 0.90 ± 0.56 and 1.53 ± 1.10 minutes, respectively; (2) the ratios of the damping times to the periods (τ /P) observed in the stellar QPPs (1.69 ± 0.56) are statistically identical to those of solar QPPs (1.74 ± 0.77) and (3) the scalings of the QPP damping time with the period are well described by the power law in both solar and stellar cases. The power indices of the solar and stellar QPPs are 0.96 ± 0.10 and 0.98+/- 0.05, respectively. This scaling is consistent with the scalings found for standing slow magnetoacoustic and kink modes in solar coronal loops. Thus, we propose that the underlying mechanism responsible for the stellar QPPs is the natural magnetohydrodynamic oscillation in the flaring or adjacent coronal loops, as in the case of solar flares.

  6. Preliminary definitions of 'flare' in axial spondyloarthritis, based on pain, BASDAI and ASDAS-CRP: an ASAS initiative.

    Science.gov (United States)

    Gossec, Laure; Portier, Agnès; Landewé, Robert; Etcheto, Adrien; Navarro-Compán, Victoria; Kroon, Féline; van der Heijde, Désirée; Dougados, Maxime

    2016-06-01

    Flares may be used as outcomes in axial spondyloarthritis (axSpA) trials or observational studies. The objective was to develop a definition for 'flare' (or worsening) in axSpA, based on validated composite indices, to be used in the context of clinical trial design. (1) Systematic literature review of definitions of 'flare' in published randomised controlled trials in axSpA. (2) Vignette exercise: 140 scenarios were constructed for a typical patient with axSpA seen at two consecutive visits. Each scenario included a change in one of the following outcomes: pain, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), BASDAI plus C-reactive protein (CRP) or Ankylosing Spondylitis Disease Activity Score (ASDAS)-CRP. Each Assessment of Spondyloarthritis (ASAS) expert determined if every scenario from a random sample of 46 scenarios was considered a flare (yes/no). Receiver-operating characteristic (ROC) analyses were applied to derive optimal cut-off values. (3) ASAS consensus was reached. (1) The literature review yielded 38 studies using some definition of 'flare', with 27 different definitions indicating important heterogeneity. The most frequent definitions were based on BASDAI changes or pain changes. (2) 121 ASAS experts completed 4999 flare assessments. The areas under the ROC curves were high (range: 0.88-0.89). Preliminary cut-offs for pain (N=3), BASDAI (N=5) and ASDAS-CRP (N=4) were chosen, with a range of sensitivity 0.60-0.99 and range of specificity 0.40-0.94 against the expert's opinions. This data-driven ASAS consensus process has led to 12 preliminary draft definitions of 'flare' in axSpA, based on widely used indices. These preliminary definitions will need validation in real patient data. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  7. The solar flare of 18 August 1979: Incoherent scatter radar data and photochemical model comparisons

    Energy Technology Data Exchange (ETDEWEB)

    Zinn, J.; Sutherland, C.D.; Fenimore, E.E.; Ganguly, S.

    1988-04-01

    Measurements of electron density at seven D-region altidues were made with the Arecibo radar during a Class-X solar flare on 18 August 1979. Measurements of solar x-ray fluxes during the same period were available from the GOES-2 satellite (0.5 to 4 /angstrom/ and 1 to 8 /angstrom/) and from ISEE-3 (in four bands between 26 and 400 keV). From the x-ray flux data we computed ionization rates in the D-region and the associated chemical changes, using a coupled atmospheric chemistry and diffusion model (with 836 chemical reactions and 19 vertical levels). The computed electron densities matched the data fairly well after we had adjusted the rate coefficients of two reactions. We discuss the hierarchies among the many flare-induced chemical reactions in two altitude ranges within the D-region and the effects of adjusting several other rate coefficients. 51 refs., 6 figs., 3 tabs.

  8. Nasal flaring

    Science.gov (United States)

    ... be caused by any of the following: Asthma flare-up Blocked airway (any cause) Swelling and mucus ... Tests that may be done include: Arterial blood gas analysis Complete blood count (CBC) ECG to check ...

  9. Flare Observations

    Directory of Open Access Journals (Sweden)

    Benz Arnold O.

    2008-02-01

    Full Text Available Solar flares are observed at all wavelengths from decameter radio waves to gamma-rays at 100 MeV. This review focuses on recent observations in EUV, soft and hard X-rays, white light, and radio waves. Space missions such as RHESSI, Yohkoh, TRACE, and SOHO have enlarged widely the observational base. They have revealed a number of surprises: Coronal sources appear before the hard X-ray emission in chromospheric footpoints, major flare acceleration sites appear to be independent of coronal mass ejections (CMEs, electrons, and ions may be accelerated at different sites, there are at least 3 different magnetic topologies, and basic characteristics vary from small to large flares. Recent progress also includes improved insights into the flare energy partition, on the location(s of energy release, tests of energy release scenarios and particle acceleration. The interplay of observations with theory is important to deduce the geometry and to disentangle the various processes involved. There is increasing evidence supporting reconnection of magnetic field lines as the basic cause. While this process has become generally accepted as the trigger, it is still controversial how it converts a considerable fraction of the energy into non-thermal particles. Flare-like processes may be responsible for large-scale restructuring of the magnetic field in the corona as well as for its heating. Large flares influence interplanetary space and substantially affect the Earth’s lower ionosphere. While flare scenarios have slowly converged over the past decades, every new observation still reveals major unexpected results, demonstrating that solar flares, after 150 years since their discovery, remain a complex problem of astrophysics including major unsolved questions.

  10. Magnetohydrodynamic Simulation of the X2.2 Solar Flare on 2011 February 15: I. Comparison with the Observations

    CERN Document Server

    Inoue, S; Magara, T; Choe, G S; Park, Y D

    2014-01-01

    We performed a magnetohydrodynamic (MHD) simulation using a nonlinear force-free field (NLFFF) in solar active region 11158 to clarify the dynamics of an X2.2-class solar flare. We found that the NLFFF never shows the drastic dynamics seen in observations, i.e., it is in stable state against the perturbations. On the other hand, the MHD simulation shows that when the strongly twisted lines are formed at close to the neutral line, which are produced via tether-cutting reconnection in the twisted lines of the NLFFF, consequently they erupt away from the solar surface via the complicated reconnection. This result supports the argument that the strongly twisted lines formed in NLFFF via tether-cutting reconnection are responsible for breaking the force balance condition of the magnetic fields in the lower solar corona. In addition to this the dynamical evolution of these field lines reveals that at the initial stage the spatial pattern of the footpoints caused by the reconnection of the twisted lines appropriatel...

  11. Microwave imaging of a solar limb flare - Comparison of spectra and spatial geometry with hard X-rays

    Science.gov (United States)

    Schmahl, E. J.; Kundu, M. R.; Dennis, B. R.

    1985-01-01

    A solar limb flare was mapped using the Very Large Array (VLA) together with hard X-ray (HXR) spectral and spatial observations of the Solar Maximum Mission satellite. Microwave flux records from 2.8 to 19.6 GHz were instrumental in determining the burst spectrum, which has a maximum at 10 GHz. The flux spectrum and area of the burst sources were used to determine the number of electrons producing gyrosynchrotron emission, magnetic field strength, and the energy distribution of gyrosynchrotron-emitting electrons. Applying the thick target model to the HXR spectrum, the number of high energy electrons responsible for the X-ray bursts was found to be 10 to the 36th, and the electron energy distribution was approximately E exp -5, significantly different from the parameters derived from the microwave observations. The HXR imaging observations exhibit some similiarities in size and structure o the first two burst sources mapped with the VLA. However, during the initial burst, the HXR source was single and lower in the corona than the double 6 cm source. The observations are explained in terms of a single loop with an isotropic high-energy electron distribution which produced the microwaves, and a larger beamed component which produced the HXR at the feet of the loop.

  12. Comparison between Hinode/SOT and SDO/HMI, AIA Data for the Study of the Solar Flare Trigger Process

    CERN Document Server

    Bamba, Yumi; Imada, Shinsuke; Iida, Yusuke

    2014-01-01

    To elucidate the flare trigger mechanism, we have analyzed several flare events which were observed by Hinode/Solar Optical Telescope (SOT), in our previous study. Because of the limitation of SOT field of view, however, only four events in the Hinode data sets have been utilizable. Therefore, increasing the number of events is required for evaluating the flare trigger models. We investigated the applicability of data obtained by the Solar Dynamics Observatory (SDO) to increase the data sample for a statistical analysis of the flare trigger process. SDO regularly observes the full disk of the sun and all flares although its spatial resolution is lower than that of Hinode. We investigated the M6.6 flare which occurred on 13 February 2011 and compared the analyzed data of SDO with the results of our previous study using Hinode/SOT data. Filter and vector magnetograms obtained by the Helioseismic and Magnetic Imager (HMI) and filtergrams from the Atmospheric Imaging Assembly (AIA) 1600A were employed. From the c...

  13. 2D MHD and 1D HD models of a solar flare -- a comprehensive comparison of the results

    CERN Document Server

    Falewicz, R; Murawski, K; Srivastava, A K

    2015-01-01

    Without any doubt solar flaring loops possess a multi-thread internal structure that is poorly resolved and there are no means to observe heating episodes and thermodynamic evolution of the individual threads. These limitations cause fundamental problems in numerical modelling of flaring loops, such as selection of a structure and a number of threads, and an implementation of a proper model of the energy deposition process. A set of 1D hydrodynamic and 2D magnetohydrodynamic models of a flaring loop are developed to compare energy redistribution and plasma dynamics in the course of a prototypical solar flare. Basic parameters of the modeled loop are set according to the progenitor M1.8 flare recorded in the AR10126 on September 20, 2002 between 09:21 UT and 09:50 UT. The non-ideal 1D models include thermal conduction and radiative losses of the optically thin plasma as energy loss mechanisms, while the non-ideal 2D models take into account viscosity and thermal conduction as energy loss mechanisms only. The 2...

  14. Performance comparison of the Alcon Legacy 20000 straight and flared 0.9 mm Aspiration Bypass System tips.

    Science.gov (United States)

    Davison, James A

    2002-01-01

    To compare the efficiency of surgical procedures using 2 phacoemulsification tips. Wolfe Clinic, Marshalltown, Iowa, USA. A randomized prospective study of 256 consecutive cases was conducted. The patients were adults having phacoemulsification by a modified in situ fracture technique. All cases were done by 1 surgeon using the Alcon Legacy 20000 phacoemulsification machine with high-vacuum cassettes and tubing. One of 2 45-degree Aspiration Bypass System (ABS) phacoemulsification tips was used. The straight tip has a 0.9 mm outside diameter (n = 127). The flared tip has a 0.76 mm outside diameter shaft that flares to a 1.02 mm tip (n = 129). Measurements at the time of surgery included metered phacoemulsification time, percentage power used, total phacoemulsification time, and milliliters of balanced salt solution (BSS(R)) used. No posterior capsule tear, vitreous loss, incision thermal damage, incision leak, or suture closure occurred. There were no cases of iris aspiration into the working end of the phacoemulsification needle; however, the iris was aspirated into the ABS opening of the flared tip in 1 case. Similar measurements for the straight and flared tips included, respectively, metered phacoemulsification time, 1.4 minutes each; mean power percentage, 41% and 39%; total phacoemulsification time, 2 minutes 11 seconds and 2 minutes 15 seconds; and overall BSS volume, 77 mL and 75 mL. The anterior capsule tear rates for straight (5.5%) and flared (1.6%) tips were similar. The flared ABS phaco tip with a 0.76 mm shaft outside diameter provided the physical advantages of shaft diameter reduction and required ultrasonic energy expenditures, BSS volumes, and surgical times similar to those of the straight ABS ultrasonic tip with a 0.9 mm outside diameter.

  15. Pre-Flare Flows in the Corona

    Science.gov (United States)

    Wallace, A. J.; Harra, L. K.; van Driel-Gesztelyi, L.; Green, L. M.; Matthews, S. A.

    2010-12-01

    Solar flares take place in regions of strong magnetic fields and are generally accepted to be the result of a resistive instability leading to magnetic reconnection. When new flux emerges into a pre-existing active region it can act as a flare and coronal mass ejection trigger. In this study we observed active region 10955 after the emergence of small-scale additional flux at the magnetic inversion line. We found that flaring began when additional positive flux levels exceeded 1.38×1020 Mx (maxwell), approximately 7 h after the initial flux emergence. We focussed on the pre-flare activity of one B-class flare that occurred on the following day. The earliest indication of activity was a rise in the non-thermal velocity one hour before the flare. 40 min before flaring began, brightenings and pre-flare flows were observed along two loop systems in the corona, involving the new flux and the pre-existing active region loops. We discuss the possibility that reconnection between the new flux and pre-existing loops before the flare drives the flows by either generating slow mode magnetoacoustic waves or a pressure gradient between the newly reconnected loops. The subsequent B-class flare originated from fast reconnection of the same loop systems as the pre-flare flows.

  16. Comparison between Two Bromine Containing Free Radical Initiators in PRESAGE®

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyeonsuk; Ryu, Dongmin; Ye, Sung-Joon [Seoul National University, Seoul (Korea, Republic of)

    2016-10-15

    PRESAGE® is an optically clear 3-D polyurethane dosimeter which contains a halogenated carbon as a free radical initiator and leucomalachite dye. The change of the optical density is known to be linear with respect to the absorbed dose and the sensitivity is related to the carbon–halogen bond dissociation energy of the free radical initiator. Although there are some studies regarding free radical initiators and dye materials, there’s a lack of reports about the effect of other elements like LMG solvent which can be added when there’s a difficulty mixing materials. Also, there are some studies about comparison between free radicals with different kind of halogen atoms but there’s a lack of studies of comparison between initiators with the same halogen atom. In this experiments, two kinds of halocarbon free radical initiator with the same halogen atom (bromine) as well as the effect of the LMG solvent were studied to use the dosimeter as a therapeutic purpose. Effective atomic numbers were also calculated. The initiators with the same halogen atom, CBr{sub 4} and C{sub 2}H{sub 2}Br{sub 4}, reacted totally differently. CBr{sub 4} was more sensitive to the radiation and emitted maximum 4 times more free radicals upon irradiation with no additional effective atomic number but the absorbance after irradiation was highly variable with time. For stable measurement, C{sub 2}H{sub 2}Br{sub 4} would be more appropriate as a free radical initiator.

  17. The Shape of M Dwarf Flares in Kepler Light Curves

    CERN Document Server

    Davenport, James R A

    2015-01-01

    Ultra-precise light curves from Kepler provide the best opportunity to determine rates and statistical properties of stellar flares. From 11 months of data on the active M4 dwarf, GJ 1243, we have built the largest catalog of flares for a single star: over 6100 events. Combining 885 of our most pristine flares, we generated an empirical white-light flare template. This high-fidelity template shows a rapid initial rise, and two distinct exponential cooling phases. This template is useful in constraining flare energies and for improved flare detection in many surveys. Complex, multi-peaked events are more common for higher energy flares in this sample. Using our flare template we characterize the structure of complex events. In this contributed talk, I presented results from our boutique study of GJ 1243, and described an expanded investigation of the structure of complex flares and their connection to solar events.

  18. Flare energetics: analysis of a large flare on YZ Canis Minoris observed simultaneously in the ultraviolet, optical and radio.

    Science.gov (United States)

    van den Oord, G. H. J.; Doyle, J. G.; Rodono, M.; Gary, D. E.; Henry, G. W.; Byrne, P. B.; Linsky, J. L.; Haisch, B. M.; Pagano, I.; Leto, G.

    1996-06-01

    The results of coordinated observations of the dMe star YZ CMi at optical, UV and radio wavelengths during 3-7 February 1983 are presented. YZ CMi showed repeated optical flaring with the largest flare having a magnitude of 3.8 in the U-band. This flare coincided with an IUE exposure which permits a comparison of the emission measure curves of YZ CMi in its flaring and quiescent state. During the flare a downward shift of the transition zone is observed while the radiative losses in the range 10^4^-10^7^K strongly increase. The optical flare is accompanied with a radio flare at 6cm, while at 20cm no emission is detected. The flare is interpreted in terms of optically thick synchrotron emission. We present a combined interpretation of the optical/radio flare and show that the flare can be interpreted within the context of solar two-ribbon/white-light flares. Special attention is paid to the bombardment of dMe atmospheres by particle beams. We show that the characteristic temperature of the heated atmosphere is almost independent of the beam flux and lies within the range of solar white-light flare temperatures. We also show that it is unlikely that stellar flares emit black-body spectra. The fraction of accelerated particles, as follows from our combined optical/radio interpretation is in good agreement with the fraction determined by two-ribbon flare reconnection models.

  19. Temporal Variability of Methane Flares on the Cascadia Margin Imaged with Swath Bathymetric Data (Ancillary Data to Cascadia Initiative Cruise AT26-02)

    Science.gov (United States)

    Trehu, A. M.

    2013-12-01

    The primary objective of AT26-02 was to recover 30 Lamont-Doherty Earth Observatory (LDEO) ocean bottom seismometers (OBSs) deployed in 2012 as part of the year two deployment of the Cascadia Initiative. This objective was met. Because many of the instruments were close together in an array focused near the Mendocino Triple Junction and the ship's crew and the instrumentation teams could not work continuously for two weeks without a break, we had the opportunity to hold station next to a methane vent for ~10 hours and image the temporal variability of methane expulsion using the water column imaging option of the EM122 swath bathymetric system on the R/V Atlantis. We also made two additional crossings of this vent while transiting between sites. This vent, which emanates from seafloor at 1800 m water depth near the base of the slope near 40.5°N, was initially discovered and reported by Gardner et al. (EOS, 2009). The rate of methane expulsion was quite variable during the time window of our observations and showed spatial variability as a single highly reflective column emerging from the seafloor split into multiple streams as it rose above 1000m. Acoustic backscatter decreased markedly at ~600 m water depth, which corresponds to the depth of the gas hydrate stability boundary (ghsb) in this region as indicated by an XBT taken near this site. Shorter time series (~2 hours each) were obtained from the summits of South and North Hydrate Ridge (NHR) on the transit back to port. At NHR, many points of bubble emergence were imaged on the seafloor. Several short-lived (~2 min) but bright acoustic flares extended well above the top of the ghsb suggesting occasional armoring of methane bubbles by something other than gas hydrate, as previously reported by Kannberg et al. (EPSL, 2013). Data are currently being processed with Fledermaus mid-water processing software. The science party for this cruise included co-chief scientists Anne Trehu (Oregon State Un.) and Dean

  20. Empirical studies of solar flares: Comparison of X-ray and H alpha filtergrams and analysis of the energy balance of the X-ray plasma

    Science.gov (United States)

    Moore, R. L.

    1979-01-01

    The physics of solar flares was investigated through a combined analysis of X-ray filtergrams of the high temperature coronal component of flares and H alpha filtergrams of the low temperature chromospheric component. The data were used to study the magnetic field configuration and its changes in solar flares, and to examine the chromospheric location and structure of X-ray bright points (XPB) and XPB flares. Each topic and the germane data are discussed. The energy balance of the thermal X-ray plasma in flares, while not studied, is addressed.

  1. Initial NIF Shock Timing Experiments: Comparison with Simulation

    Science.gov (United States)

    Robey, H. F.; Celliers, P. M.; Boehly, T. R.; Datte, P. S.; Bowers, M. W.; Olson, R. E.; Munro, D. H.; Milovich, J. L.; Jones, O. S.; Nikroo, A.; Kroll, J. J.; Horner, J. B.; Hamza, A. V.; Bhandarkar, S. D.; Giraldez, E.; Castro, C.; Gibson, C. R.; Eggert, J. H.; Smith, R. F.; Park, H.-S.; Young, B. K.; Hsing, W. W.; Landen, O. L.; Meyerhofer, D. D.

    2010-11-01

    Initial experiments are underway to demonstrate the techniques required to tune the shock timing of capsule implosions on the National Ignition Facility (NIF). These experiments use a modified cryogenic hohlraum geometry designed to precisely match the performance of ignition hohlraums. The targets employ a re-entrant Au cone to provide optical access to the shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of the shocks is diagnosed with VISAR (Velocity Interferometer System for Any Reflector) and DANTE. The results of these measurements will be used to set the precision pulse shape for ignition capsule implosions to follow. Experimental results and comparisons with numerical simulation are presented.

  2. IMPULSIVITY PARAMETER FOR SOLAR FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo-Mendieta, W. G.; Alvarado-Gómez, J. D.; Calvo-Mozo, B. [Observatorio Astronómico Nacional, Universidad Nacional de Colombia, Bogotá (Colombia); Martinez-Oliveros, J. C., E-mail: wgfajardom@unal.edu.co, E-mail: bcalvom@unal.edu.co, E-mail: oliveros@ssl.berkeley.edu, E-mail: jalvarad@eso.org [Space Sciences Laboratory, UC Berkeley, Berkeley, CA 94720 (United States)

    2016-02-10

    Three phases are typically observed during solar flares: the preflare, impulsive, and decay phases. During the impulsive phase, it is believed that the electrons and other particles are accelerated after the stored energy in the magnetic field is released by reconnection. The impulsivity of a solar flare is a quantifiable property that shows how quickly this initial energy release occurs. It is measured via the impulsivity parameter, which we define as the inverse of the overall duration of the impulsive phase. We take the latter as the raw width of the most prominent nonthermal emission of the flare. We computed this observable over a work sample of 48 M-class events that occurred during the current Solar Cycle 24 by using three different methods. The first method takes into account all of the nonthermal flare emission and gives very accurate results, while the other two just cover fixed energy intervals (30–40 keV and 25–50 keV) and are useful for fast calculations. We propose an alternative way to classify solar flares according to their impulsivity parameter values, defining three different types of impulsivity, namely, high, medium, and low. This system of classification is independent of the manner used to calculated the impulsivity parameter. Lastly, we show the relevance of this tool as a discriminator of different HXR generation processes.

  3. Turbulence, Complexity, and Solar Flares

    CERN Document Server

    McAteer, R T James; Conlon, Paul A

    2009-01-01

    The issue of predicting solar flares is one of the most fundamental in physics, addressing issues of plasma physics, high-energy physics, and modelling of complex systems. It also poses societal consequences, with our ever-increasing need for accurate space weather forecasts. Solar flares arise naturally as a competition between an input (flux emergence and rearrangement) in the photosphere and an output (electrical current build up and resistive dissipation) in the corona. Although initially localised, this redistribution affects neighbouring regions and an avalanche occurs resulting in large scale eruptions of plasma, particles, and magnetic field. As flares are powered from the stressed field rooted in the photosphere, a study of the photospheric magnetic complexity can be used to both predict activity and understand the physics of the magnetic field. The magnetic energy spectrum and multifractal spectrum are highlighted as two possible approaches to this.

  4. KEPLER FLARES. I. ACTIVE AND INACTIVE M DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Hawley, Suzanne L.; Davenport, James R. A.; Kowalski, Adam F.; Wisniewski, John P.; Deitrick, Russell; Hilton, Eric J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Hebb, Leslie, E-mail: slhawley@uw.edu [Department of Physics, Hobart and William Smith Colleges, 300 Pulteney Street, Geneva, NY 14456 (United States)

    2014-12-20

    We analyzed Kepler short-cadence M dwarf observations. Spectra from the Astrophysical Research Consortium 3.5 m telescope identify magnetically active (Hα in emission) stars. The active stars are of mid-M spectral type, have numerous flares, and have well-defined rotational modulation due to starspots. The inactive stars are of early M type, exhibit less starspot signature, and have fewer flares. A Kepler to U-band energy scaling allows comparison of the Kepler flare frequency distributions with previous ground-based data. M dwarfs span a large range of flare frequency and energy, blurring the distinction between active and inactive stars designated solely by the presence of Hα. We analyzed classical and complex (multiple peak) flares on GJ 1243, finding strong correlations between flare energy, amplitude, duration, and decay time, with only a weak dependence on rise time. Complex flares last longer and have higher energy at the same amplitude, and higher energy flares are more likely to be complex. A power law fits the energy distribution for flares with log E{sub K{sub p}}> 31 erg, but the predicted number of low-energy flares far exceeds the number observed, at energies where flares are still easily detectable, indicating that the power-law distribution may flatten at low energy. There is no correlation of flare occurrence or energy with starspot phase, the flare waiting time distribution is consistent with flares occurring randomly in time, and the energies of consecutive flares are uncorrelated. These observations support a scenario where many independent active regions on the stellar surface are contributing to the observed flare rate.

  5. Flare plasma dynamics obseved with the YOHKOH Bragg crystal spectrometer. III. Spectral signatures of electron-beam-heated atmospheres.

    Science.gov (United States)

    Marriska, John. T.

    1995-05-01

    Using numerical simulations of an electon-beam-heated solar flare, we investigate the observational consequences of variations in the electron beam total energy flux and the low-energy cut off value for models with both low and high initial densities. To do this we use the evolution of the physical parameters of the simulated flares to synthesize the time evolution of the spectrum in the wavelength region surrounding tha Ca xix resonance line. These spectra are then summed over a 9 s time interval to simulate typical spectra from the Yohkoh Bragg crystal spectometer and the first three moments are computed for comparison with observational results. This comparison shows that no single low or high initial density model satisfies the observed average behavior of the Ca xix resonance line. Low initial density models produce too large a blue shift velocity, while high initial density model have lines that are too narrow. Comparison of these models with the Yohkok data suggests that the key problem for models of the impulsive phase ofa solar flare is producing significant amounts of stationary hot plasma early in the flare.

  6. Impulsivity Parameter for Solar Flares

    CERN Document Server

    Fajardo-Mendieta, W G; Alvarado-Gómez, J D; Calvo-Mozo, B

    2016-01-01

    Three phases are typically observed during solar flares: the preflare, impulsive, and decay phases. During the impulsive phase, it is believed that the electrons and other particles are accelerated after the stored energy in the magnetic field is released by reconnection. The impulsivity of a solar flare is a quantifiable property that shows how quickly this initial energy release occurs. It is measured via the impulsivity parameter, which we define as the inverse of the overall duration of the impulsive phase. We take the latter as the raw width of the most prominent nonthermal emission of the flare. We computed this observable over a work sample of 48 M-class events that occurred during the current Solar Cycle 24 by using three different methods. The first method takes into account all of the nonthermal flare emission and gives very accurate results, while the other two just cover fixed energy intervals (30-40 keV and 25-50 keV) and are useful for fast calculations. We propose an alternative way to classify...

  7. Observation and analysis of ballistic downflows in a M-class flare using IRIS

    Science.gov (United States)

    Brannon, Sean

    2016-05-01

    Despite significant advances in instrumentation, there remain no studies that analyze observations of on-disk flare loop plasma flows covering the entire evolution from chromospheric evaporation, through plasma cooling, to draining downflows. We present results from an imaging and spectroscopic observation from the Interface Region Imaging Spectrograph (IRIS) of the SOL2015-03-12T11:50:00 M-class flare, at high spatial resolution and time cadence. Our analysis of this event reveals initial plasma evaporation at flare temperatures indicated by 100-200 km/s blueshifts in the Fe XXI line. We subsequently observe plasma cooling into chromospheric lines (Si IV and O IV) with ~11 minute delay, followed by loop draining at ~40 km/s as indicated by a ``C''-shaped redshift structure and significant (~60 km/s) non-thermal broadening. We use density sensitive lines to calculate a plasma density for the flare loops, and estimate a theoretical cooling time approximately equal to the observed delay. Finally, we use a simple elliptical free-fall draining model to construct synthetic spectra, and perform what we believe to be the first direct comparison of such synthetic spectra to observations of draining downflows in flare loops.

  8. Solar Flares and Variation of Local Geomagnetic Field: Measurements by the Huancayo Observatory over 2001-2010

    Science.gov (United States)

    Carlos Reyes, Rafael E.; Gárate Ayesta, Gabriel A.; Reyes Navarro, Felipe A.

    2017-02-01

    We study the local variation of the geomagnetic field measured by the Huancayo Geomagnetic Observatory, Peru, during 2001-2010. Initially, we sought to relate the SFI values, stored daily in the NOAA's National Geophysical Data Center, with the corresponding geomagnetic index; however, no relation was observed. Nonetheless, subsequently, a comparison between the monthly geomagnetic-activity index and the monthly SFI average allowed observing a temporal correlation between these average indices. This correlation shows that the effect of the solar flares does not simultaneously appear on the corresponding magnetic indices. To investigate this, we selected the most intense X-class flares; then, we checked the magnetic field disturbances observed in the Huancayo Geomagnetic Observatory magnetograms. We found some disturbances of the local geomagnetic field in the second and third day after the corresponding solar flare; however, the disturbance strength of the local geomagnetic field is not correlated with the X-class of the solar flare. Finally, there are some disturbances of the local geomagnetic field that are simultaneous with the X-class solar flares and they show a correlation with the total flux of the solar flare.

  9. Multi-wavelength view of an M2.2 Solar Flare on 26 November 2000

    CERN Document Server

    Chandra, R; Rani, S; Maurya, R A

    2016-01-01

    In this paper, we present a study of an M2.2 class solar flare of 26 November 2000 from NOAA AR 9236. The flare was well observed by various ground based observatories (ARIES, Learmonths Solar Observatory) and space borne instruments (SOHO, HXRS, GOES) in time interval between 02:30 UT to 04:00 UT. The flare started with long arc-shape outer flare ribbon. Afterwards the main flare starts with two main ribbons. Initially the outer ribbons start to expand with an average speed ($\\sim$ 20 km s$^{-1}$) and later it shows contraction. The flare was associated with partial halo coronal mass ejection (CMEs) which has average speed of 495 km s$^{-1}$. The SOHO/MDI observations show that the active region was in quadrupolar magnetic configuration. The flux cancellation was observed before the flare onset close to flare site. Our analysis indicate the flare was initiated by the magnetic breakout mechanism.

  10. Multi-wavelength view of an M2.2 solar flare on 26 november 2000

    Science.gov (United States)

    Chandra, R.; Verma, V. K.; Rani, S.; Maurya, R. A.

    2017-02-01

    In this paper, we present a study of an M2.2 class solar flare of 26 November 2000 from NOAA AR 9236. The flare was well observed by various ground based observatories (ARIES, Learmonths Solar Observatory) and space borne instruments (SOHO, HXRS, GOES) in time interval between 02:30 UT to 04:00 UT. The flare started with long arc-shape outer flare ribbon. Afterwards the main flare starts with two main ribbons. Initially the outer ribbons start to expand with an average speed (∼20 km s-1) and later it shows contraction. The flare was associated with partial halo coronal mass ejection (CMEs) which has average speed of 495 km s-1. The SOHO/MDI observations show that the active region was in quadrupolar magnetic configuration. The flux cancellation was observed before the flare onset close to flare site. Our analysis indicate the flare was initiated by the magnetic breakout mechanism.

  11. Predictability of Solar Flares

    Science.gov (United States)

    Mares, Peter; Balasubramaniam, K. S.

    2009-05-01

    Solar flares are significant drivers of space weather. With the availability of high cadence solar chromospheric and photospheric data from the USAF's Optical Solar PAtrol Network (OSPAN; photosphere and chromosphere imaging) Telescope and the Global Oscillations Network Group (GONG; photosphere magnetic imaging), at the National Solar Observatory, we have gained insights into potential uses of the data for solar flare prediction. We apply the Principal Component Analysis (PCA) to parameterize the flaring system and extract consistent observables at solar chromospheric and photospheric layers that indicate a viable recognition of flaring activity. Rather than limiting ourselves to a few known indicators of solar activity, PCA helps us to characterize the entire system using several tens of variables for each observed layer. The components of the Eigen vectors derived from PCA help us recognize and quantify innate characteristics of solar flares and compare them. We will present an analysis of these results to explore the viability of PCA to assist in predicting solar flares.

  12. Solar Flares: Magnetohydrodynamic Processes

    Directory of Open Access Journals (Sweden)

    Kazunari Shibata

    2011-12-01

    Full Text Available This paper outlines the current understanding of solar flares, mainly focused on magnetohydrodynamic (MHD processes responsible for producing a flare. Observations show that flares are one of the most explosive phenomena in the atmosphere of the Sun, releasing a huge amount of energy up to about 10^32 erg on the timescale of hours. Flares involve the heating of plasma, mass ejection, and particle acceleration that generates high-energy particles. The key physical processes for producing a flare are: the emergence of magnetic field from the solar interior to the solar atmosphere (flux emergence, local enhancement of electric current in the corona (formation of a current sheet, and rapid dissipation of electric current (magnetic reconnection that causes shock heating, mass ejection, and particle acceleration. The evolution toward the onset of a flare is rather quasi-static when free energy is accumulated in the form of coronal electric current (field-aligned current, more precisely, while the dissipation of coronal current proceeds rapidly, producing various dynamic events that affect lower atmospheres such as the chromosphere and photosphere. Flares manifest such rapid dissipation of coronal current, and their theoretical modeling has been developed in accordance with observations, in which numerical simulations proved to be a strong tool reproducing the time-dependent, nonlinear evolution of a flare. We review the models proposed to explain the physical mechanism of flares, giving an comprehensive explanation of the key processes mentioned above. We start with basic properties of flares, then go into the details of energy build-up, release and transport in flares where magnetic reconnection works as the central engine to produce a flare.

  13. Sgr A* flares: tidal disruption of asteroids and planets?

    NARCIS (Netherlands)

    Zubovas, K.; Nayakshin, S.; Markoff, S.

    2012-01-01

    It is theoretically expected that a supermassive black hole (SMBH) in the centre of a typical nearby galaxy disrupts a solar-type star every ∼105 yr, resulting in a bright flare lasting for months. Sgr A*, the resident SMBH of the Milky Way, produces (by comparison) tiny flares that last only hours

  14. Solar flares. [plasma physics

    Science.gov (United States)

    Rust, D. M.

    1979-01-01

    The present paper deals with explosions in a magnetized solar plasma, known as flares, whose effects are seen throughout the electromagnetic spectrum, from gamma-rays through the visible and to the radio band. The diverse phenomena associated with flares are discussed, along with the physical mechanisms that have been advanced to explain them. The impact of solar flare research on the development of plasma physics and magnetohydrodynamics is noted. The rapid development of solar flare research during the past 20 years, owing to the availability of high-resolution images, detailed magnetic field measurements, and improved spectral data, is illustrated.

  15. Initial stability comparison of modular hip implants in synthetic femurs.

    Science.gov (United States)

    Lee, T Q; Danto, M I; Kim, W C

    1998-08-01

    Synthetic femurs were used to assess the initial bone-implant interface stability of three total hip systems: Wright Medical Technology's Infinity smooth trochanteric module (S-TM), Infinity porous-coated trochanteric module (PC-TM), and Johnson and Johnson S-ROM with a porous surface. The hips were implanted into synthetic femurs, rigidly fixed, and subjected to internal rotation and cyclic, axial compressive loads. The results showed that all three implants achieved good initial implant stability and would be expected to permit bone ingrowth. The porous-coated implants showed greater initial implant stability with less axial micromotion compared with the smooth implants. This finding suggests that surface texture plays a role in initial stability of uncemented prostheses if the bone behaves similar to the material used in this study.

  16. Feasibility and Domain Validation of Rheumatoid Arthritis (RA) Flare Core Domain Set

    DEFF Research Database (Denmark)

    Bartlett, Susan J; Bykerk, Vivian P; Cooksey, Roxanne

    2015-01-01

    OBJECTIVE: The Outcome Measures in Rheumatology (OMERACT) Rheumatoid Arthritis (RA) Flare Group was established to develop an approach to identify and measure RA flares. An overview of our OMERACT 2014 plenary is provided. METHODS: Feasibility and validity of flare domains endorsed at OMERACT 11...... (2012) were described based on initial data from 3 international studies collected using a common set of questions specific to RA flare. Mean flare frequency, severity, and duration data were presented, and domain scores were compared by flare status to examine known-groups validity. Breakout groups......, and stiffness scores averaged ≥ 2 times higher (2 of 11 points) in flaring individuals. Correlations between flare domains and corresponding legacy instruments were obtained: r = 0.46 to 0.93. A combined definition (patient report of flare and 28-joint Disease Activity Score increase) was evaluated in 2 other...

  17. Characteristics of the Polarity Inversion Line and Solar Flare Forecasts

    Science.gov (United States)

    Sadykov, Viacheslav M.; Kosovichev, Alexander G.

    2017-08-01

    Studying connection between solar flares and properties of magnetic field in active regions is very important for understanding the flare physics and developing space weather forecasts. In this work, we analyze relationship between the flare X-ray peak flux from the GOES satellite, and characteristics of the line-of-sight (LOS) magnetograms obtained by the SDO/HMI instrument during the period of April, 2010 - June, 2016. We try to answer two questions: 1) What characteristics of the LOS magnetic field are most important for the flare initiation and magnitude? 2) Is it possible to construct a reliable forecast of ≥ M1.0 and ≥ X1.0 class flares based only on the LOS magnetic field characteristics? To answer these questions, we apply a Polarity Inversion Line (PIL) detection algorithm, and derive various properties of the PIL and the corresponding Active Regions (AR). The importance of these properties for flare forecasting is determined by their ability to separate flaring cases from non-flaring, and their Fisher ranking score. It is found that the PIL characteristics are of special importance for the forecasts of both ≥ M1.0 and ≥ X1.0 flares, while the global AR characteristics become comparably discriminative only for ≥ X1.0 flares. We use the Support Vector Machine (SVM) classifier and train it on the six characteristics of the most importance for each case. The obtained True Skill Statistics (TSS) values of 0.70 for ≥ M1.0 flares and 0.64 for ≥ X1.0 flares are better than the currently-known expert-based predictions. Therefore, the results confirm the importance of the LOS magnetic field data and, in particular, the PIL region characteristics for flare forecasts.

  18. Absolute Abundance Measurements in Solar Flares

    Science.gov (United States)

    Warren, Harry

    2014-06-01

    We present measurements of elemental abundances in solar flares with EVE/SDO and EIS/Hinode. EVE observes both high temperature Fe emission lines Fe XV-XXIV and continuum emission from thermal bremsstrahlung that is proportional to the abundance of H. By comparing the relative intensities of line and continuum emission it is possible to determine the enrichment of the flare plasma relative to the composition of the photosphere. This is the first ionization potential or FIP bias (F). Since thermal bremsstrahlung at EUV wavelengths is relatively insensitive to the electron temperature it is important to account for the distribution of electron temperatures in the emitting plasma. We accomplish this by using the observed spectra to infer the differential emission measure distribution and FIP bias simultaneously. In each of the 21 flares that we analyze we find that the observed composition is close to photospheric. The mean FIP bias in our sample is F=1.17+-0.22. Furthermore, we have compared the EVE measurements with corresponding flare observations of intermediate temperature S, Ar, Ca, and Fe emission lines taken with EIS. Our initial calculations also indicate a photospheric composition for these observations. This analysis suggests that the bulk of the plasma evaporated during a flare comes from deep in the chromosphere, below the region where elemental fractionation in the non-flaring corona occurs.

  19. Physics of Transient Seismic Emission from Flares

    Science.gov (United States)

    Lindsey, Charles A.; Donea, A.; Malanushenko, A.

    2012-05-01

    We consider the physics of seismic activity in solar flares, i.e., the release of powerful seismic transients into the solar interior during the impulsive phases of some flares. Recent work by Hudson, Fisher, Welsch and Bercik has attracted a great deal of positive attention to the possible role of Lorentz-force transients in driving seismic transient emission in flares. The implications of direct involvement by magnetic forces in seismic transient emission, if this could be confirmed, would be major, since magnetic fields are thought to hold the energy source of the flares themselves. The energy invested into acoustic transients is a small fraction of the total released by the flare, but requires a massive impulse many times that required to accelerate high-energy electrons into which the energy is initially thought to be invested. What does this say about a flare mechanism that sometimes does both? We discuss some of the outstanding diagnostic questions that confront the recognition of magnetic-field transients associated with Lorentz force transients based on resources HMI, Hinode, AIA and other facilities offer us.

  20. Modeling High Resolution Flare Spectra Using Hydrodynamic Simulations

    Science.gov (United States)

    Warren, Harry; Doschek, G.

    2006-06-01

    Understanding the hydrodynamic response of the solar atmosphere to the release of energy during a flare has been a long standing problem in solar physics. Early time-dependent hydrodynamic simulations were able to reproduce the high temperatures and densities observed in solar flares, but were not able to model the observations in any detail. For example, these simulations could not account for the relatively slow decay of the observed emission or the absence of blueshifts in high spectral resolution line profiles at flare onset. We have found that by representing the flare as a succession of independently heated filaments it is possible to reproduce both the evolution of line intensity and the shape of the line profile using hydrodynamic simulations. Here we present detailed comparisons between our simulation results and several flares observed with the Yohkoh Bragg Crystal Spectrometer (BCS). Comparisons with 3D MHD simulations will also be discussed.

  1. Fractional Differential Equations in Terms of Comparison Results and Lyapunov Stability with Initial Time Difference

    Directory of Open Access Journals (Sweden)

    Coşkun Yakar

    2010-01-01

    Full Text Available The qualitative behavior of a perturbed fractional-order differential equation with Caputo's derivative that differs in initial position and initial time with respect to the unperturbed fractional-order differential equation with Caputo's derivative has been investigated. We compare the classical notion of stability to the notion of initial time difference stability for fractional-order differential equations in Caputo's sense. We present a comparison result which again gives the null solution a central role in the comparison fractional-order differential equation when establishing initial time difference stability of the perturbed fractional-order differential equation with respect to the unperturbed fractional-order differential equation.

  2. Observation and Analysis of Ballistic Downflows in an M-class Flare with the Interface Region Imaging Spectrograph

    Science.gov (United States)

    Brannon, Sean R.

    2016-12-01

    Despite significant advances in instrumentation, there remain no studies that analyze observations of on-disk flare loop plasma flows covering the entire evolution from chromospheric evaporation, through plasma cooling, to draining downflows. We present results from an imaging and spectroscopic observation from the Interface Region Imaging Spectrograph (IRIS) of the SOL2015-03-12T11:50:00 M-class flare, at high spatial resolution and time cadence. Our analysis of this event reveals initial plasma evaporation at flare temperatures indicated by 100-200 km s-1 blueshifts in the Fe xxi line. We subsequently observe plasma cooling into chromospheric lines (Si iv and O iv) with ˜11 minute delay, followed by loop draining at ˜40 km s-1 as indicated by a “C”-shaped redshift structure and significant (˜60 km s-1) non-thermal broadening. We use density-sensitive lines to calculate a plasma density for the flare loops, and estimate a theoretical cooling time approximately equal to the observed delay. Finally, we use a simple elliptical free-fall draining model to construct synthetic spectra, and perform what we believe to be the first direct comparison of such synthetic spectra to observations of draining downflows in flare loops.

  3. Solar Features - Solar Flares

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A solar flare is a short-lived sudden increase in the intensity of radiation emitted in the neighborhood of sunspots. For many years it was best monitored in the...

  4. What Causes Lupus Flares?

    Science.gov (United States)

    Fernandez, David; Kirou, Kyriakos A

    2016-03-01

    Systemic lupus erythematosus (SLE), the prototypic systemic autoimmune disease, follows a chronic disease course, punctuated by flares. Disease flares often occur without apparent cause, perhaps from progressive inherent buildup of autoimmunity. However, there is evidence that certain environmental factors may trigger the disease. These include exposure to UV light, infections, certain hormones, and drugs which may activate the innate and adaptive immune system, resulting in inflammation, cytotoxic effects, and clinical symptoms. Uncontrolled disease flares, as well as their treatment, especially with glucocorticoids, can cause significant organ damage. Tight surveillance and timely control of lupus flares with judicial use of effective treatments to adequately suppress the excessive immune system activation are required to bring about long term remission of the disease. We hope that new clinical trials will soon offer additional effective and target-specific biologic treatments for SLE.

  5. Gamma-ray flare activity from PSR B1259-63 during 2014 periastron passage and comparison to its 2010 passage

    CERN Document Server

    Caliandro, G A; Li, J; Scargle, J D; Torres, D F; Wood, K S; Chernyakova, M

    2015-01-01

    PSR B1259-63/LS 2883 is a gamma-ray binary system containing a radio pulsar in a highly elliptical ~3.4-year orbit around a Be star. In its 2010 periastron passage, multiwavelength emission from radio to TeV was observed, as well as an unexpected GeV flare measured by the Fermi Large Area Telescope (LAT). Here, we report the results of LAT monitoring of PSR B1259-63 during its most recent 2014 periastron passage. We compare the gamma-ray behavior in this periastron with the former in 2010 and find that PSR B1259-63 shows a recurrent GeV flare. The similarities and differences in the phenomenology of both periastron passages are discussed.

  6. Identifying flares in rheumatoid arthritis

    DEFF Research Database (Denmark)

    Bykerk, Vivian P; Bingham, Clifton O; Choy, Ernest H

    2016-01-01

    Set. METHODS: Candidate flare questions and legacy measures were administered at consecutive visits to Canadian Early Arthritis Cohort (CATCH) patients between November 2011 and November 2014. The American College of Rheumatology (ACR) core set indicators were recorded. Concordance to identify flares...... to flare, with escalation planned in 61%. CONCLUSIONS: Flares are common in rheumatoid arthritis (RA) and are often preceded by treatment reductions. Patient/MD/DAS agreement of flare status is highest in patients worsening from R/LDA. OMERACT RA flare questions can discriminate between patients with...

  7. Kepler Flares I. Active and Inactive M dwarfs

    CERN Document Server

    Hawley, Suzanne L; Kowalski, Adam F; Wisniewski, John P; Hebb, Leslie; Deitrick, Russell; Hilton, Eric J

    2014-01-01

    We analyzed Kepler short-cadence M dwarf observations. Spectra from the ARC 3.5m telescope identify magnetically active (H$\\alpha$ in emission) stars. The active stars are of mid-M spectral type, have numerous flares, and well-defined rotational modulation due to starspots. The inactive stars are of early-M type, exhibit less starspot signature, and have fewer flares. A Kepler to U-band energy scaling allows comparison of the Kepler flare frequency distributions with previous ground-based data. M dwarfs span a large range of flare frequency and energy, blurring the distinction between active and inactive stars designated solely by the presence of H$\\alpha$. We analyzed classical and complex (multiple peak) flares on GJ 1243, finding strong correlations between flare energy, amplitude, duration and decay time, with only a weak dependence on rise time. Complex flares last longer and have higher energy at the same amplitude, and higher energy flares are more likely to be complex. A power law fits the energy dist...

  8. Safe and efficient flare gas recovery; Safety flaring

    Energy Technology Data Exchange (ETDEWEB)

    Gross-Petersen, Joergen; Wills, Martin; Johnston, Ian

    2010-07-01

    Flaring of gas in connection with the production of hydrocarbons represents both an undesirable emission to the atmosphere and a loss of valuable resource. As part of the efforts further to reduce flaring Maersk Oil consider installation of Flare Gas Recovery (FGR) where appropriate, significant efforts have therefor been made by Maersk Oil as operator for Danish Underground Consortium (DUC) to reduce the flaring from the facilities operated in the Danish North Sea. (Author)

  9. Flaring variability of Microquasars

    CERN Document Server

    Trushkin, Sergei A; Nizhelskij, Nikolaj A

    2008-01-01

    We discuss flaring variability of radio emission of microquasars, measured in monitoring programs with the RATAN-600 radio telescope. We carried out a multi-frequency (1-30 GHz) daily monitoring of the radio flux variability of the microquasars SS433, GRS1915+105, and Cyg X-3 during the recent sets in 2005-2007. A lot of bright short-time flares were detected from GRS 1915+105 and they could be associated with active X-ray events. In January 2006 we detected a drop down of the quiescent fluxes from Cyg X-3 (from 100 to $\\sim$20 mJy), then the 1 Jy-flare was detected on 2 February 2006 after 18 days of quenched radio emission. The daily spectra of the flare in the maximum were flat from 2 to 110 GHz, using the quasi-simultaneous observations at 110 GHz with the RT45m telescope and the NMA millimeter array of NRO in Japan. Several bright radio flaring events (1-15 Jy) followed during the continuing state of very variable and intensive 1-12 keV X-ray emission ($\\sim$0.5 Crab), which was monitored in the RXTE ASM...

  10. Flare Plasma Iron Abundance

    Science.gov (United States)

    Dennis, Brian R.; Dan, Chau; Jain, Rajmal; Schwartz, Richard A.; Tolbert, Anne K.

    2008-01-01

    The equivalent width of the iron-line complex at 6.7 keV seen in flare X-ray spectra suggests that the iron abundance of the hottest plasma at temperatures >approx.10 MK may sometimes be significantly lower than the nominal coronal abundance of four times the photospheric value that is commonly assumed. This conclusion is based on X-ray spectral observations of several flares seen in common with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Solar X-ray Spectrometer (SOXS) on the second Indian geostationary satellite, GSAT-2. The implications of this will be discussed as it relates to the origin of the hot flare plasma - either plasma already in the corona that is directly heated during the flare energy release process or chromospheric plasma that is heated by flare-accelerated particles and driven up into the corona. Other possible explanations of lower-than-expected equivalent widths of the iron-line complex will also be discussed.

  11. Interactive Multi-Instrument Database of Solar Flares (IMIDSF)

    Science.gov (United States)

    Sadykov, Viacheslav M.; Nita, Gelu M.; Oria, Vincent; Kosovichev, Alexander G.

    2017-08-01

    Solar flares represent a complicated physical phenomenon observed in a broad range of the electromagnetic spectrum, from radiowaves to gamma-rays. For a complete understanding of the flares it is necessary to perform a combined multi-wavelength analysis using observations from many satellites and ground-based observatories. For efficient data search, integration of different flare lists and representation of observational data, we have developed the Interactive Multi-Instrument Database of Solar Flares (https://solarflare.njit.edu/). The web database is fully functional and allows the user to search for uniquely-identified flare events based on their physical descriptors and availability of observations of a particular set of instruments. Currently, data from three primary flare lists (GOES, RHESSI and HEK) and a variety of other event catalogs (Hinode, Fermi GBM, Konus-Wind, OVSA flare catalogs, CACTus CME catalog, Filament eruption catalog) and observing logs (IRIS and Nobeyama coverage), are integrated. An additional set of physical descriptors (temperature and emission measure) along with observing summary, data links and multi-wavelength light curves is provided for each flare event since January 2002. Results of an initial statistical analysis will be presented.

  12. Automated flare prediction using the AdaBoost algorithm

    Institute of Scientific and Technical Information of China (English)

    Ru-Shi Lan; Yong Jiang; Liu-Guan Ding; Jian-Wei Yang

    2012-01-01

    We propose a flare prediction method based on the AdaBoost algorithm,which constructs a strong prediction model from a combination of several basic models.Three predictors,extracted from the photospheric magnetograms,are applied as features to predict the occurrence of flares with a certain level over 24 hours following the time when the magnetogram is recorded.To demonstrate the effectiveness of the proposed method,comparisons of experimental results with respect to some existing methods are given.The results show that an improvement is achieved in predicting the occurrences of large flares.

  13. Diagnostics of solar flare reconnection

    Directory of Open Access Journals (Sweden)

    M. Karlický

    2004-01-01

    Full Text Available We present new diagnostics of the solar flare reconnection, mainly based on the plasma radio emission. We propose that the high-frequency (600-2000 MHz slowly drifting pulsating structures map the flare magnetic field reconnection. These structures correspond to the radio emission from plasmoids which are formed in the extended current sheet due to tearing and coalescence processes. An increase of the frequency drift of the drifting structures is interpreted as an increase of the reconnection rate. Using this model, time scales of slowly drifting pulsating structure observed during the 12 April 2001 flare by the Trieste radiopolarimeter with high time resolution (1 ms are interpreted as a radio manifestation of electron beams accelerated in the multi-scale reconnection process. For short periods Fourier spectra of the observed structure have a power-law form with power-law indices in the 1.3-1.6 range. For comparison the 2-D MHD numerical modeling of the multi-scale reconnection is made and it is shown that Fourier spectrum of the reconnection dissipation power has also a power-law form, but with power-law index 2. Furthermore, we compute a time evolution of plasma parameters (density, magnetic field etc in the 2-D MHD model of the reconnection. Then assuming a plasma radio emission from locations, where the 'double-resonance' instability generates the upper-hybrid waves due to unstable distribution function of suprathermal electrons, we model radio spectra. Effects of the MHD turbulence are included. The resulting spectra are compared with those observed. It is found, that depending on model parameters the lace bursts and the decimetric spikes can be reproduced. Thus, it is shown that the model can be used for diagnostics of the flare reconnection process. We also point out possible radio signatures of reconnection outflow termination shocks. They are detected as type II-like herringbone structures in the 200-700 MHz frequency range. Finally

  14. Precursor flares in OJ 287

    OpenAIRE

    Pihajoki, P.; Valtonen, M.; Zola, S.; Liakos, A.; Drozdz, M.; Winiarski, M.; Ogloza, W.; Koziel-Wierzbowska, D.; Provencal, J.; Nilsson, K.; Berdyugin, A.; Lindfors, E.; Reinthal, R.; Sillanpää, A.; Takalo, L.

    2012-01-01

    We have studied three most recent precursor flares in the light curve of the blazar OJ 287 while invoking the presence of a precessing binary black hole in the system to explain the nature of these flares. Precursor flare timings from the historical light curves are compared with theoretical predictions from our model that incorporate effects of an accretion disk and post-Newtonian description for the binary black hole orbit. We find that the precursor flares coincide with the secondary black...

  15. The Giant Flare from SGR 1900+14

    Science.gov (United States)

    Feroci, M.; Hurley, K.; Duncan, R. C.; Thompson, C.

    2000-10-01

    We present a joint analysis of the Ulysses (25-150 keV) and BeppoSAX/GRBM (40-700 keV) data on the giant flare of 1998 August 27 from SGR 1900+14. This event was extraordinary in many ways: it was the most intense flux of gamma rays ever detected from a source outside our solar system; it was longer than any previously detected burst from a soft gamma repeater (SGR) in our Galaxy by more than an order of magnitude; and it showed a remarkable four-peaked, periodic pattern in hard X-rays with the same 5.16-s period that was observed in X-rays from the quiescent star. Since the two instruments operate in different energy ranges, a comparison of their data allow for both time-average and time-resolved spectral studies. We discuss some implications of these results for the SGRs. We also compare this event with the 1979 March 5 giant flare from SGR 0526-26, by newly-analyzed Venera/SIGNE and ISEE-3 data. Our results are consistent with the hypothesis that giant flares are due to catastrophic magnetic instabilities in highly magnetized neutron stars, or ``magnetars". In particular, observations indicate that the initial hard spike involved a relativistic outflow of pairs and hard gamma rays, plausibly triggered by a large propagating fracture in the crust of a neutron star with a field exceeding 1014 Gauss. Later stages in the light curve are accurately fit by a model for emission from the envelope of a magnetically-confined pair-photon fireball, anchored to the surface of the rotating star, which contracts as it emits X-rays and then evaporates completely in a finite time. The complex four-peaked shape of the light curve likely provides the most direct evidence known for a multipolar geometry in the magnetic field of a neutron star.

  16. Models for Flare Statistics and the Waiting-time Distribution of Solar Flare Hard X-ray Bursts

    Science.gov (United States)

    Wheatland, M. S.; Edney, S. D.

    1999-12-01

    In a previous study (Wheatland, Sturrock, McTiernan 1998), a waiting-time distribution was constructed for solar flare hard X-ray bursts observed by the ICE/ISEE-3 spacecraft. A comparison of the observed distribution with that of a time-dependent Poisson process indicated an overabundance of short waiting times (10~s -- 10~min), implying that the hard X-ray bursts are not independent events. Models for flare statistics assume or predict that flares are independent events -- in particular the avalanche model makes this specific prediction. The results of the previous study may be reconciled with the avalanche picture if individual flares produce several distinct bursts of hard X-ray emission. A detailed comparison of the avalanche model and the ICE/ISEE-3 waiting-time distribution is presented here.

  17. Active Region Emergence and Remote Flares

    Science.gov (United States)

    Fu, Yixing; Welsch, Brian T.

    2016-02-01

    We study the effect of new emerging solar active regions on the large-scale magnetic environment of existing regions. We first present a theoretical approach to quantify the "interaction energy" between new and pre-existing regions as the difference between i) the summed magnetic energies of their individual potential fields and ii) the energy of their superposed potential fields. We expect that this interaction energy can, depending upon the relative arrangements of newly emerged and pre-existing magnetic flux, indicate the existence of "topological" free magnetic energy in the global coronal field that is independent of any "internal" free magnetic energy due to coronal electric currents flowing within the newly emerged and pre-existing flux systems. We then examine the interaction energy in two well-studied cases of flux emergence, but find that the predicted energetic perturbation is relatively small compared to energies released in large solar flares. Next, we present an observational study of the influence of the emergence of new active regions on flare statistics in pre-existing active regions, using NOAA's Solar Region Summary and GOES flare databases. As part of an effort to precisely determine the emergence time of active regions in a large event sample, we find that emergence in about half of these regions exhibits a two-stage behavior, with an initial gradual phase followed by a more rapid phase. Regarding flaring, we find that the emergence of new regions is associated with a significant increase in the occurrence rate of X- and M-class flares in pre-existing regions. This effect tends to be more significant when pre-existing and new emerging active regions are closer. Given the relative weakness of the interaction energy, this effect suggests that perturbations in the large-scale magnetic field, such as topology changes invoked in the "breakout" model of coronal mass ejections, might play a significant role in the occurrence of some flares.

  18. An Unusual Burst from Soft Gamma Repeater SGR 1900+14 Comparisons with Giant Flares and Implications for the Magnetar Model

    CERN Document Server

    Ibrahim, A I; Woods, P M; Kouveliotou, C; Thompson, C; Duncan, R C; Dieters, S W; Van Paradijs, J; Finger, M H; Ibrahim, Alaa I.; Strohmayer, Tod E.; Woods, Peter M.; Kouveliotou, Chryssa; Thompson, Christopher; Duncan, Robert C.; Dieters, Stefan; Paradijs, Jan van; Finger, Mark

    2001-01-01

    The Soft Gamma Repeater SGR 1900+14 entered a remarkable phase of activity during the summer of 1998. This activity peaked on August 27, 1998 when a giant periodic gamma-ray flare resembling the famous March 5, 1979 event from SGR 0526-66 was recorded. Two days later (August 29), a strong, bright burst was detected with RXTE and BATSE. This event reveals several similarities to the giant flares of August 27 and March 5, and shows a number of unique features not previously seen in SGR bursts. Unlike typically short SGR bursts, this event features a 3.5 s burst peak that was preceded by an extended (~ 1 s) complex precursor, and followed by a long (~ 1000 s) periodic tail modulated at the 5.16 s stellar rotation period. Spectral analysis shows a striking distinction between the spectral behavior of the precursor, burst peak and extended tail. While the spectrum during the peak is uniform, a significant spectral evolution is detected in both the precursor and tail emissions. Temporal behavior shows a sharp rise ...

  19. Case study of the mesospheric and lower thermospheric effects of solar X-ray flares: coupled ion-neutral modelling and comparison with EISCAT and riometer measurements

    Energy Technology Data Exchange (ETDEWEB)

    Enell, C.F.; Vierinen, J.P.; Kero, A.; Ulich, T.; Turunen, E. [Oulu Univ., Sodankylae (Finland). Sodankylae Geophysical Observatory; Verronen, P.T.; Seppaelae, A. [Finnish Meteorological Inst., Helsinki (Finland). Earth Observation unit; Beharrell, M.J.; Honary, F. [Lancaster Univ. (United Kingdom). Dept. of Communication Systems

    2008-07-01

    Two case studies of upper mesospheric and lower thermospheric (UMLT) high-latitude effects of solar X-ray flares are presented. SodankylaeIon-neutral Chemistry Model (SIC) electron density profiles agree with D-region EISCAT and riometer observations, provided that the profiles of the most variable ionisable component, nitric oxide, are adjusted to compensate for NO{sub x} production during preceding geomagnetically active periods. For the M6-class flare of 27 April 2006, following a quiet period, the agreement with cosmic noise absorption observed by the Sodankylaeriometers was within reasonable limits without adjustment of the [NO] profile. For the major (X17-class) event of 28 October 2003, following high auroral activity and solar proton events, the NO concentration had to be increased up to on the order of 10{sup 8} cm{sup -3} at the D-region minimum. Thus [NO] can in principle be measured by combining SIC with observations, if the solar spectral irradiance and particle precipitation are adequately known. As the two case events were short and modelled for high latitudes, the resulting neutral chemical changes are insignificant. However, changes in the model ion chemistry occur, including enhancements of water cluster ions. (orig.)

  20. Modeling the Soft X-Ray During Solar Flares

    Science.gov (United States)

    Leaman, C. J.

    2016-12-01

    Solar Radiation can effect our communication and navigation systems here on Earth. In particular, solar X-ray (SXR) and extreme ultraviolet (EUV) radiation is responsible for ionizing (charging) earth's upper atmosphere, and sudden changes in the ionosphere can disrupt high frequency communication systems (e.g. airplane-to-ground) and degrade the location accuracy for GPS navigation. New soft X-ray flare data are needed to study the sources for the SXR radiation and variability of the solar flares and thus help to answer questions if all flares follow the same trend or have different plasma characteristics? In December 2015, the Miniature X-Ray Solar Spectrometer (MinXSS) launched from Cape Canaveral Florida to answer those questions. The MinXSS CubeSat is a miniature satellite that was designed to measure the soft X-ray spectra and study flares in the 1-15 Å wavelength range. So far, the CubeSat has observed more than ten flares. The MinXSS flare data are plotted in energy vs irradiance to display the soft X-ray spectra, and these spectra are compared with different types of CHIANTI models of the soft X-ray radiation. One comparison is for non-flaring spectra using AIA EUV images to identify solar features called active regions, coronal holes, and quiet sun, and then using the fractional area of each feature to calculate a CHIANTI-based spectrum. This comparison reveals how important the active region radiation is for the SXR spectra. A second comparison is for flare spectra to several isothermal models that were created using CHIANTI. The isothermal model comparisons were done with both the raw count spectra from MinXSS and the derived irradiance spectra. This dual comparison helps to validate the irradiance conversion algorithm for MinXSS. Comparisons of the MinXSS data to the models show that flares tend to follow a temperature pattern. Analysis of the MinXSS data can help us understand our sun better, could lead to better forecasts of solar flares, and thus

  1. Flare Heating in Stellar Coronae

    CERN Document Server

    Kashyap, V L; Güdel, M; Audard, M; Kashyap, Vinay; Drake, Jeremy; Guedel, Manuel; Audard, Marc

    2002-01-01

    We investigate the contribution of very weak flares to the coronal luminosity of low-mass active stars. We analyze EUVE/DS events data from FK Aqr, V1054 Oph, and AD Leo and conclude that in all these cases the coronal emission is dominated by flares to such an extent that in some cases the entire emission may be ascribed to flare heating. We have developed a new method to directly model for the first time stochastically produced flare emission, including undetectable flares, and their effects on the observed photon arrival times. We find that the index of the power-law distribution of flare energies (dN/dE ~ E^{-alpha}) is 2.6+-0.34, 2.74+-0.35, and 2.03-2.32 for FK Aqr, V1054 Oph, and AD Leo respectively. We also find that the flare component accounts for a large fraction (generally >50 percent) of the total flux.

  2. Two-Step Coronal Transport of Solar Flare Particles from Magnetic Multipolarity Sources in a Flare Region

    Institute of Scientific and Technical Information of China (English)

    HUANG Yong-Nian; WANG Shi-Jin

    2001-01-01

    The transport of solar flare particles in the corona is studied. Considering the problems in terms of the character istics of a sunspot group producing solar cosmic rays and solar flare processes, we find that formation of the fast propagation process is associated with annihilation of sunspots in the group with magnetic multipolarity. The slower propagation process depends on magnetic irregularities in the corona, and the evolution of the transport is related to the flare processes. Equations for the coronal transport are proposed and their initial and boundary conditions are given. The predicted results agree with the main observational features.

  3. An experimental and theoretical study of the aeroacoustics of external-Coanda gas flares

    Science.gov (United States)

    Parsons, Caroline

    Experimental and theoretical means have been used to investigate the fluid dynamics and aeroacoustics of both stepped and unstepped external Coanda flares. Flow visualization techniques have been used to observe the one-eight scale model flare flow fields whilst simultaneously carrying out various sound measurements in the hope of being able to relate observed flow features to specific types of aerodynamic noise. Particular attention has been paid to the stepped model flare in the present work, for comparison with previous work on the unstepped model flare. Test have been carried out on two full-scale flares of different sizes which confirm that the previously assumed inverse-length scaling law does indeed hold in the case of flare noise frequency. Comparisons can therefore be made between the results of model and full-size flare tests, and these indicate that although the full-size flare also emits discrete tones, the nature of these tones are very different from those emitted by the model flares. Several possible reasons for the differences in the two sets of results are discussed. A theoretical study of the high-frequency turbulent mixing noise associated with a model Indair flare jet has been carried out. Because of the complicated nature of such a curved radial wall-jet, the theory has first been developed for a plane two-dimensional wall-jet.

  4. Ending emissions: Industry targets venting, while flaring progress lauded

    Energy Technology Data Exchange (ETDEWEB)

    Lea, N.

    2003-06-01

    The progress achieved by the multi-stakeholder solution gas flaring reduction program in Alberta is discussed. The program was initiated in 1999 by the Alberta Energy and Utilities Board (EUB); within the first three years upstream flaring of solution gas was reduced by 53 per cent. Progress has also been made in reducing volumes of solution gas venting: between 1996 and 2001, there has been a 32 per cent reduction in combined flared and vented volumes of solution gas. Well test flaring has also been reduced by reduced test durations and volumes, to wit: there has been a 3 per cent reduction in flaring volumes while well tests have increased by 23 per cent. At gas plants, the decrease in flaring and venting amounted to 19 per cent, attributed mostly to industry response to the EUB's Guide 60, which incorporates many of the recommendations of the 2002 report and recommendations of the Flaring/Venting Project Team of the Clean Air Strategic Alliance (CASA).

  5. The first observed stellar X-ray flare oscillation: Constraints on the flare loop length and the magnetic field

    CERN Document Server

    Mitra-Kraev, U; Williams, D R; Kraev, E

    2005-01-01

    We present the first X-ray observation of an oscillation during a stellar flare. The flare occurred on the active M-type dwarf AT Mic and was observed with XMM-Newton. The soft X-ray light curve (0.2-12 keV) is investigated with wavelet analysis. The flare's extended, flat peak shows clear evidence for a damped oscillation with a period of around 750 s, an exponential damping time of around 2000 s, and an initial, relative peak-to-peak amplitude of around 15%. We suggest that the oscillation is a standing magneto-acoustic wave tied to the flare loop, and find that the most likely interpretation is a longitudinal, slow-mode wave, with a resulting loop length of (2.5 +- 0.2) e10 cm. The local magnetic field strength is found to be (105 +- 50) G. These values are consistent with (oscillation-independent) flare cooling time models and pressure balance scaling laws. Such a flare oscillation provides an excellent opportunity to obtain coronal properties like the size of a flare loop or the local magnetic field stre...

  6. Gamma-ray Burst Flares: X-ray Flaring. II

    CERN Document Server

    Swenson, C A

    2013-01-01

    We present a catalog of 497 flaring periods found in gamma-ray burst (GRB) light curves taken from the online XRT GRB Catalogue. We analyzed 680 individual light curves using a flare detection method developed and used on our UV/optical GRB Flare Catalog. The method makes use of the Bayesian Information Criterion to analyze the residuals of fitted GRB light curves and statistically determines the optimal fit to the light curve residuals in attempt to identify any additional features. These features, which we classify as flares, are identified by iteratively adding additional `breaks' to the light curve. We find evidence of flaring in 310 of the analyzed light curves. For those light curves with flares, we find an average number of ~1.5 flares per GRB. As with the UV/optical, flaring in our sample is generally confined to the first 1000 s of the afterglow, but can be detected to beyond 10^5 s. Only ~50% of the detected flares follow the `classical' definition of \\Delta t/t << 1, with many of the largest ...

  7. PRECURSOR FLARES IN OJ 287

    Energy Technology Data Exchange (ETDEWEB)

    Pihajoki, P.; Berdyugin, A.; Lindfors, E.; Reinthal, R.; Sillanpaeae, A.; Takalo, L. [Tuorla Observatory, Department of Physics and Astronomy, University of Turku, FI-21500 Piikkioe (Finland); Valtonen, M.; Nilsson, K. [Finnish Centre for Astronomy with ESO, University of Turku, FI-21500 Piikkioe (Finland); Zola, S.; Koziel-Wierzbowska, D. [Astronomical Observatory, Jagiellonian University, ul. Orla 171, PL-30-244 Krakow (Poland); Liakos, A. [Department of Astrophysics, Astronomy and Mechanics, University of Athens, GR 157 84 Zografos, Athens, Hellas (Greece); Drozdz, M.; Winiarski, M.; Ogloza, W. [Mount Suhora Observatory, Pedagogical University, ul. Podchorazych 2, PL-30-084 Krakow (Poland); Provencal, J. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Santangelo, M. M. M. [O.A.C. Osservatorio Astronomico di Capannori, Via di Valle, I-55060 Vorno, Capannori (Italy); Salo, H. [Department of Physical Sciences, University of Oulu, P.O. Box 3000, FI-90014 University of Oulu (Finland); Chandra, S.; Ganesh, S.; Baliyan, K. S., E-mail: popiha@utu.fi [Astronomy and Astrophysics Division, Physical Research Laboratory, Ahmedabad 380009 (India); and others

    2013-02-10

    We have studied three most recent precursor flares in the light curve of the blazar OJ 287 while invoking the presence of a precessing binary black hole in the system to explain the nature of these flares. Precursor flare timings from the historical light curves are compared with theoretical predictions from our model that incorporate effects of an accretion disk and post-Newtonian description for the binary black hole orbit. We find that the precursor flares coincide with the secondary black hole descending toward the accretion disk of the primary black hole from the observed side, with a mean z-component of approximately z{sub c} = 4000 AU. We use this model of precursor flares to predict that precursor flare of similar nature should happen around 2020.96 before the next major outburst in 2022.

  8. Comparison of trunk activity during gait initiation and walking in humans.

    Directory of Open Access Journals (Sweden)

    Jean-Charles Ceccato

    Full Text Available To understand the role of trunk muscles in maintenance of dynamic postural equilibrium we investigate trunk movements during gait initiation and walking, performing trunk kinematics analysis, Erector spinae muscle (ES recordings and dynamic analysis. ES muscle expressed a metachronal descending pattern of activity during walking and gait initiation. In the frontal and horizontal planes, lateroflexion and rotation occur before in the upper trunk and after in the lower trunk. Comparison of ES muscle EMGs and trunk kinematics showed that trunk muscle activity precedes corresponding kinematics activity, indicating that the ES drive trunk movement during locomotion and thereby allowing a better pelvis mobilization. EMG data showed that ES activity anticipates propulsive phases in walking with a repetitive pattern, suggesting a programmed control by a central pattern generator. Our findings also suggest that the programs for gait initiation and walking overlap with the latter beginning before the first has ended.

  9. Comparison of Trunk Activity during Gait Initiation and Walking in Humans

    Science.gov (United States)

    Azevedo, Christine; Cazalets, Jean-René

    2009-01-01

    To understand the role of trunk muscles in maintenance of dynamic postural equilibrium we investigate trunk movements during gait initiation and walking, performing trunk kinematics analysis, Erector spinae muscle (ES) recordings and dynamic analysis. ES muscle expressed a metachronal descending pattern of activity during walking and gait initiation. In the frontal and horizontal planes, lateroflexion and rotation occur before in the upper trunk and after in the lower trunk. Comparison of ES muscle EMGs and trunk kinematics showed that trunk muscle activity precedes corresponding kinematics activity, indicating that the ES drive trunk movement during locomotion and thereby allowing a better pelvis mobilization. EMG data showed that ES activity anticipates propulsive phases in walking with a repetitive pattern, suggesting a programmed control by a central pattern generator. Our findings also suggest that the programs for gait initiation and walking overlap with the latter beginning before the first has ended. PMID:19997606

  10. Relationship between CME dynamics and solar flare plasma

    Institute of Scientific and Technical Information of China (English)

    Rajmal Jain; Malini Aggarwal; Pradeep Kulkarni

    2010-01-01

    The relationship between the velocity of CMEs and the plasma temperature of the associated X-ray solar flares is investigated.The velocity of CMEs increases with plasma temperature(R=0.82)and photon index below the break energy(R=0.60)of X-ray flares.The heating of the coronal plasma appears to be significant with respect to the kinetics of a CME from the reconnection region where the flare also occurs.We propose that the initiation and velocity of CMEs perhaps depend upon the dominant process of conversion of the magnetic field energy of the active region to heating/accelerating the coronal plasma in the reconnected loops.Results show that a flare and the associated CME are two components of one energy release system,perhaps,magnetic field free energy.

  11. Analysis of ultraviolet and X-ray observations of three homologous solar flares from SMM

    Science.gov (United States)

    Cheng, Chung-Chieh; Pallavicini, Roberto

    1987-01-01

    Three homologous flares observed in the UV lines of Fe XXI and O V and in X-rays from the SMM were studied. It was found that: (1) the homology of the flares was most noticeable in Fe XXI and soft X-ray emissions; (2) the three flares shared many of the same loop footprints which were located in O V bright kernals associated with hard X-ray bursts; and (3) in spite of the strong spatial homology, the temporal evolution in UV and X-ray emissions varied from flare to flare. A comparison between the UV observations and photospheric magnetograms revealed that the basic flare configuration was a complex loop system consisting of many loops or bundles of loops.

  12. Predictions of reconnected flux, energy and helicity in eruptive solar flares

    Science.gov (United States)

    Kazachenko, Maria Dmitiyevna

    2010-12-01

    In order to better understand the solar genesis of interplanetary magnetic clouds, I model the magnetic and topological properties of several large eruptive solar flares and relate them to observations. My main hypothesis is that the flux ropes ejected during eruptive solar flares are the result of a sequence of magnetic reconnections. To test this hypothesis, I use the three-dimensional Minimum Current Corona model of flare energy storage (Longcope, 1996) together with pre-flare photospheric magnetic field and flare ribbon observations to predict the basic flare properties: reconnected magnetic flux, free energy, and flux rope helicity. Initially, the MCC model was able to quantify the properties of the flares that occur in active regions with only photospheric shearing motions. Since rotating motions may also play a key role in the flare energetics, I develop a method for including both shearing and rotating motions into the MCC model. I use this modified method to predict the model flare properties and then compare them to the observed quantities. Firstly, for two flares in active regions with fast rotating sunspots, I find that the relative importance of shearing and rotation to those flares depends critically on their location within the parent active region topology. Secondly, for four flares analyzed with the MCC model (three flares described here and one flare described in Longcope et al. (2007)), I find that the modeled flare properties agree with the observed properties within the uncertainties of the methods used. This agreement compels me to believe that the magnetic clouds associated with these four solar flares are formed by low-corona magnetic reconnection during the eruption as modeled by the MCC model, rather than eruption of pre-existing structures in the corona or formation in the upper corona with participation of the global magnetic field. I note that since all four flares occurred in active regions without significant pre-flare flux emergence

  13. The flares of August 1972. [solar flare characteristics and spectra

    Science.gov (United States)

    Zirin, H.; Tanaka, K.

    1973-01-01

    Observations of the August, 1972 flares at Big Bear and Tel Aviv, involving monochromatic movies, magnetograms, and spectra, are analyzed. The region (McMath 11976) showed inverted polarity from its inception on July 11; the great activity was due to extremely high shear and gradients in the magnetic field, as well as a constant invasion of one polarity into the opposite; observations in lambda 3835 show remarkable fast flashes in the impulsive flare of 18:38 UT on Aug. 2 with lifetimes of 5 sec, which may be due to dumping of particles in the lower chromosphere. Flare loops show evolutionary increases of their tilts to the neutral line in the flares of Aug. 4 and 7. Spectroscopic observations show red asymmetry and red shift of the H alpha emission in the flash phase of the Aug. 7 flare, as well as substantial velocity shear in the photosphere during the flare, somewhat like earthquake movement along a fault. Finally the total H alpha emission of the Aug. 7 flare could be measured accurately as about 2.5 x 10 to the 30th power erg, considerably less than coarser previous estimates for great flares.

  14. GRB Flares: UV/Optical Flaring (Paper I)

    CERN Document Server

    Swenson, C A; De Pasquale, M; Oates, S R

    2013-01-01

    We present a new algorithm for the detection of flares in gamma-ray burst (GRB) light curves and use this algorithm to detect flares in the UV/optical. The algorithm makes use of the Bayesian Information Criterion (BIC) to analyze the residuals of the fitted light curve, removing all major features, and to determine the statistically best fit to the data by iteratively adding additional `breaks' to the light curve. These additional breaks represent the individual components of the detected flares: T_start, T_stop, and T_peak. We present the detection of 119 unique flaring periods detected by applying this algorithm to light curves taken from the Second Swift Ultraviolet/Optical Telescope (UVOT) GRB Afterglow Catalog. We analyzed 201 UVOT GRB light curves and found episodes of flaring in 68 of the light curves. For those light curves with flares, we find an average number of ~2 flares per GRB. Flaring is generally restricted to the first 1000 seconds of the afterglow, but can be observed and detected beyond 10...

  15. Solar flare leaves sun quaking

    Science.gov (United States)

    1998-05-01

    Dr. Alexander G. Kosovichev, a senior research scientist from Stanford University, and Dr. Valentina V. Zharkova from Glasgow (United Kingdom) University found the tell-tale seismic signature in data on the Sun's surface collected by the Michelson Doppler Imager onboard the Solar and Heliospheric Observatory (SOHO) spacecraft immediately following a moderate-sized flare on July 9, 1996. "Although the flare was a moderate one, it still released an immense amount of energy," said Dr. Craig Deforest, a researcher with the SOHO project. "The energy released is equal to completely covering the Earth's continents with a yard of dynamite and detonating it all at once." SOHO is a joint project of the European Space Agency and NASA. The finding is reported in the May 28 issue of the journal Nature, and is the subject of a press conference at the spring meeting of the American Geophysical Union in Boston, Mass., May 27. The solar quake that the science team recorded looks much like ripples spreading from a rock dropped into a pool of water. But over the course of an hour, the solar waves traveled for a distance equal to 10 Earth diameters before fading into the fiery background of the Sun's photosphere. Unlike water ripples that travel outward at a constant velocity, the solar waves accelerated from an initial speed of 22,000 miles per hour to a maximum of 250,000 miles per hour before disappearing. "People have looked for evidence of seismic waves from flares before, but they didn't have a theory so they didn't know where to look," says Kosovichev. Several years ago Kosovichev and Zharkova developed a theory that can explain how a flare, which explodes in space above the Sun's surface, can generate a major seismic wave in the Sun's interior. According to the currently accepted model of solar flares, the primary explosion creates high-energy electrons (electrically charged subatomic particles). These are funneled down into a magnetic flux tube, an invisible tube of magnetic

  16. Sunspot waves and flare energy release

    CERN Document Server

    Sych, R; Altyntsev, A; Dudík, J; Kashapova, L

    2014-01-01

    We address a possibility of the flare process initiation and further maintenance of its energy release due to a transformation of sunspot longitudinal waves into transverse magnetic loop oscillations with initiation of reconnection. This leads to heating maintaining after the energy release peak and formation of a flat stage on the X-ray profile. We applied the time-distance plots and pixel wavelet filtration (PWF) methods to obtain spatio-temporal distribution of wave power variations in SDO/AIA data. To find magnetic waveguides, we used magnetic field extrapolation of SDO/HMI magnetograms. The propagation velocity of wave fronts was measured from their spatial locations at specific times. In correlation curves of the 17 GHz (NoRH) radio emission we found a monotonous energy amplification of 3-min waves in the sunspot umbra before the 2012 June 7 flare. This dynamics agrees with an increase in the wave-train length in coronal loops (SDO/AIA, 171 {\\AA}) reaching the maximum 30 minutes prior to the flare onset...

  17. Initial Results of Aperture Area Comparisons for Exo-Atmospheric Total Solar Irradiance Measurements

    Science.gov (United States)

    Johnson, B. Carol; Litorja, Maritoni; Fowler, Joel B.; Butler, James J.

    2009-01-01

    In the measurement of exo-atmospheric total solar irradiance (TSI), instrument aperture area is a critical component in converting solar radiant flux to irradiance. In a May 2000 calibration workshop for the Total Irradiance Monitor (TIM) on the Earth Observing System (EOS) Solar Radiation and Climate Experiment (SORCE), the solar irradiance measurement community recommended that NASA and NISI coordinate an aperture area measurement comparison to quantify and validate aperture area uncertainties and their overall effect on TSI uncertainties. From May 2003 to February 2006, apertures from 4 institutions with links to the historical TSI database were measured by NIST and the results were compared to the aperture area determined by each institution. The initial results of these comparisons are presented and preliminary assessments of the participants' uncertainties are discussed.

  18. Replication Validity of Initial Association Studies: A Comparison between Psychiatry, Neurology and Four Somatic Diseases

    Science.gov (United States)

    Dumas-Mallet, Estelle; Button, Katherine; Boraud, Thomas; Munafo, Marcus; Gonon, François

    2016-01-01

    Context There are growing concerns about effect size inflation and replication validity of association studies, but few observational investigations have explored the extent of these problems. Objective Using meta-analyses to measure the reliability of initial studies and explore whether this varies across biomedical domains and study types (cognitive/behavioral, brain imaging, genetic and “others”). Methods We analyzed 663 meta-analyses describing associations between markers or risk factors and 12 pathologies within three biomedical domains (psychiatry, neurology and four somatic diseases). We collected the effect size, sample size, publication year and Impact Factor of initial studies, largest studies (i.e., with the largest sample size) and the corresponding meta-analyses. Initial studies were considered as replicated if they were in nominal agreement with meta-analyses and if their effect size inflation was below 100%. Results Nominal agreement between initial studies and meta-analyses regarding the presence of a significant effect was not better than chance in psychiatry, whereas it was somewhat better in neurology and somatic diseases. Whereas effect sizes reported by largest studies and meta-analyses were similar, most of those reported by initial studies were inflated. Among the 256 initial studies reporting a significant effect (p<0.05) and paired with significant meta-analyses, 97 effect sizes were inflated by more than 100%. Nominal agreement and effect size inflation varied with the biomedical domain and study type. Indeed, the replication rate of initial studies reporting a significant effect ranged from 6.3% for genetic studies in psychiatry to 86.4% for cognitive/behavioral studies. Comparison between eight subgroups shows that replication rate decreases with sample size and “true” effect size. We observed no evidence of association between replication rate and publication year or Impact Factor. Conclusion The differences in reliability

  19. Recent Developments: The Gamma Ray Imager/Polarimeter for Solar Flares (GRIPS) Imaging and Detector systems

    Science.gov (United States)

    Duncan, Nicole; Shih, A. Y.; Hurford, G. J.; Saint-Hilaire, P.; Bain, H.; Zoglauer, A.; Lin, R. P.; Boggs, S. E.

    2013-07-01

    In two of the best-observed flares of the last cycle, the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) satellite found the centroids of ion and relativistic electron emission to have a significant displacement. This result is surprising; co-spatially accelerated ions and electrons are thought to be transported along the same field lines, implying they would enter the chromosphere together and have similar emission locations. The Gamma-Ray Imager/Polarimeter for Solar Flares (GRIPS) balloon instrument will investigate particle transport in solar flares by providing enhanced imaging, spectroscopy and polarimetry of gamma/HXR flare emission (20keV - 10MeV). GRIPS’ key technological improvements over the solar state of the art in HXR/gamma ray energies (RHESSI) include three-dimensional position-sensitive germanium detectors (3D-GeDs) and a single-grid modulating collimator, the multi-pitch rotating modulator (MPRM). The 3D-GeDs allow GRIPS to Compton track energy deposition within the crystal. This capability (1) enables the MPRM design by acting as a second modulation grid, (2) provides significant background rejection and (3) makes solar polarization measurements possible. The MPRM imager provides quasi-continuous resolution from 12.5 - 162 arcsecs with 2x the throughput of a dual grid collimator system like RHESSI. This spatial resolution can resolve the separate footpoints of many flare sizes. In comparison, RHESSI images with a minimum of 35 arcsecs for gamma-rays, making these footpoints resolvable in only the largest flares. Here, we present the intial calibration of GRIPS’ 3D-GED detectors using laboratory radioactive sources. We evaluate charge sharing between adjacent strips, the detection of coincidences and preliminary depth measurements. The detectors have been shown to have a linear response and resolve line emission. The MPRM modulation grid is constructed and we present initial results from calibration. GRIPS is scheduled for a

  20. Risk of tumor flare after nivolumab treatment in patients with irradiated field recurrence.

    Science.gov (United States)

    Yoshida, Tatsuya; Furuta, Hiromi; Hida, Toyoaki

    2017-03-01

    Nivolumab offers a statistically superior survival benefit over docetaxel in patients with advanced, previously treated squamous and non-squamous non-small-cell lung cancer (NSCLC). However, we unexpectedly encountered "tumor flare" that was associated with initially increased tumor lesion size and subsequently decreased tumor burden in patients with NSCLC treated with nivolumab, which is known as pseudoprogression. Tumor flare with rapid progression related to accelerated progression after nivolumab treatment has also been observed. Here we report two patients having early irradiated field recurrence who experienced "tumor flare" that showed pseudoprogression and rapid progression. In addition, we present a brief literature review on "tumor flare" after nivolumab treatment.

  1. Patient and clinical characteristics associated with gout flares in an integrated healthcare system.

    Science.gov (United States)

    Rashid, Nazia; Levy, Gerald D; Wu, Yi-Lin; Zheng, Chengyi; Koblick, River; Cheetham, T Craig

    2015-11-01

    Gout flares have been challenging to identify in retrospective databases due to gout flares not being well documented by diagnosis codes, making it difficult to conduct accurate database studies. Previous studies have used different algorithms, and in this study, we used a computer-based method to identify gout flares. The objectives of this study were to identify gout flares in gout patients newly initiated on urate-lowering therapy and evaluate factors associated with a patient experiencing gout flares after starting drug treatment. This was a retrospective cohort study identifying gout patients newly initiated on a urate-lowering therapy (ULT) during the study time period of January 1, 2007-December 31, 2010. The index date was the first dispensed ULT prescription during the study time period. Patients had to be ≥18 years of age on index date, have no history of prior ULT prescription during 12 months before index date, and were required to have 12 months of continuous membership with drug benefit during pre-/post-index. Electronic chart notes were reviewed to identify gout flares; these reviews helped create a validated computer-based method to further identify patients with gout flares and were categorized into 0 gout flares, 1-2 gout flares, and ≥3 gout flares during the 12 months post-index period. Multivariable logistic regression was used to examine patient and clinical factors associated with gout flares during the 12-month follow-up period. There were 8905 patients identified as the final cohort and 68 % of these patients had one or more gout flares during the 12-month follow-up: 2797 patients (31 %) had 0 gout flares, 4836 (54 %) had 1-2 gout flares, and 1272 patients (14 %) had ≥3 gout flares. Using a multivariate regression analyses, factors independently associated with 1-2 gout flares and ≥3 gout flares versus no gout flares were similar, however, with slight differences, such as younger patients were more likely to have 1-2 gout flares and

  2. The COMPTEL solar flare catalog

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, J.; Varendorff, M.; McConnell, M.; Forrest, D.; Schoenfelder, V.; Lichti, G.; Diehl, R.; Rank, G.; Bennett, K.; Hanlon, L.; Winkler, W.; Swanenburg, B.; Bloemen, H. Hermsen, W.

    1993-01-01

    COMPTEL, the Imaging Compton Telescope on the Compton Gamma Ray Observatory, has registered many solar gamma ray flares during its two years on orbit. It detects and measures gamma rays from flares by two methods: (1) utilizing two independent large NaI gamma ray spectrometers operating from 0.2 to 2 MeV and 0.6 to 10 MeV and (2) using the telescope and imaging capabilities to acquire spectra from 0.75 to 30 MeV. Solar neutrons can also be measured in the telescope mode. The authors report here the solar gamma ray flare list compiled from COMPTEL data in the two modes of operation. They also describe the methods of searching for flares in the COMPTEL data and the qualitative nature of the flares detected.

  3. Magnetic Topology of the 29 October 2003 X10 flare

    Science.gov (United States)

    Des Jardins, Angela C.; Canfield, R.; Longcope, D.

    2006-06-01

    In order to improve the understanding of both flare initiation and evolution, we take advantage of powerful new topological methods and the high spatial resolution of RHESSI to examine where magnetic reconnection takes place in flare-producing solar active regions. Up to this time, such studies have been carried out on a very small number of active regions. According to present ideas, reconnection is expected to occur at either a separatrix or separator topological feature. We use the powerful X10 flare on 29 October 2003 (peak: 20:49 UT, location: (80'', 275'')) as a test of the ability to interpret the topological location of reconnection. The 29 October 2003 flare was well observed by RHESSI and MDI, occurred near the sun's central meridian, and thus is thus a prime candidate for a study on the topological location of magnetic reconnection. In this flare study, we use the MPOLE (http://solar.physics.montana.edu/dana/mpole/) software to extrapolate from the photospheric magnetic field, as observed by MDI, to a coronal field. MPOLE is a suite of IDL programs implementing the Minimum Current Corona Model (Longcope 1996) and currently includes a new method that uses a hierarchy of topological features (Beveridge 2006). The extrapolation gives the location of topological features such as poles, nulls, separatricies, separators, and spine lines. We examine the flare emission observed by RHESSI in the context of these topological features. In the case of the 29 October 2003 flare, we find a relationship between the spine lines and the temporal evolution of the HXR flare footpoints. In this poster, we present observations supporting the relationship, explore uncertainties in the consistency between MPOLE and RHESSI data, and survey possible results.This work is supported by NASA.

  4. High-energy Gamma-Ray Emission from Solar Flares: Summary of Fermi Large Area Telescope Detections and Analysis of Two M-class Flares

    Science.gov (United States)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Bonamente, E.; Bottacini, E.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chen, Q.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Desiante, R.; Digel, S. W.; Di Venere, L.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, W. N.; Kamae, T.; Kawano, T.; Knödlseder, J.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Mayer, M.; Mazziotta, M. N.; McEnery, J. E.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Murphy, R.; Nemmen, R.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Panetta, J. H.; Perkins, J. S.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Pivato, G.; Porter, T. A.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Ritz, S.; Schulz, A.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Takahashi, H.; Takeuchi, Y.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Troja, E.; Tronconi, V.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Werner, M.; Winer, B. L.; Wood, D. L.; Wood, K. S.; Wood, M.; Yang, Z.; Fermi LAT Collaboration

    2014-05-01

    We present the detections of 18 solar flares detected in high-energy γ-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. This work suggests that particle acceleration up to very high energies in solar flares is more common than previously thought, occurring even in modest flares, and for longer durations. Interestingly, all these flares are associated with fairly fast coronal mass ejections (CMEs). We then describe the detailed temporal, spatial, and spectral characteristics of the first two long-lasting events: the 2011 March 7 flare, a moderate (M3.7) impulsive flare followed by slowly varying γ-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by γ-ray emission lasting for 2 hr. We compare the Fermi LAT data with X-ray and proton data measurements from GOES and RHESSI. We argue that the γ-rays are more likely produced through pion decay than electron bremsstrahlung, and we find that the energy spectrum of the proton distribution softens during the extended emission of the 2011 March 7 flare. This would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous acceleration process at play for the duration of the flares. CME shocks are known for accelerating the solar energetic particles (SEPs) observed in situ on similar timescales, but it might be challenging to explain the production of γ-rays at the surface of the Sun while the CME is halfway to the Earth. A stochastic turbulence acceleration process occurring in the solar corona is another likely scenario. Detailed comparison of characteristics of SEPs and γ-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.

  5. Modelling repeatedly flaring delta-sunspots

    CERN Document Server

    Chatterjee, Piyali; Carlsson, Mats

    2016-01-01

    Active regions (AR) appearing on the surface of the Sun are classified into $\\alpha$, $\\beta$, $\\gamma$, and $\\delta$ by the rules of the Mount Wilson Observatory, California on the basis of their topological complexity. Amongst these, the $\\delta$-sunspots are known to be super-active and produce the most X-ray flares. Here, we present results from a simulation of the Sun by mimicking the upper layers and the corona, but starting at a more primitive stage than any earlier treatment. We find that this initial state consisting of only a thin sub-photospheric magnetic sheet breaks into multiple flux-tubes which evolve into a colliding-merging system of spots of opposite polarity upon surface emergence, similar to those often seen on the Sun. The simulation goes on to produce many exotic $\\delta$-sunspot associated phenomena: repeated flaring in the range of typical solar flare energy release and ejective helical flux ropes with embedded cool-dense plasma filaments resembling solar coronal mass ejections.

  6. Flare physics at high energies

    Science.gov (United States)

    Ramaty, R.

    1990-01-01

    High-energy processes, involving a rich variety of accelerated particle phenomena, lie at the core of the solar flare problem. The most direct manifestation of these processes are high-energy radiations, gamma rays, hard X-rays and neutrons, as well as the accelerated particles themselves, which can be detected in interplanetary space. In the study of astrophysics from the moon, the understanding of these processes should have great importance. The inner solar system environment is strongly influenced by activity on the sun; the physics of solar flares is of great intrinsic interest; and much high-energy astrophysics can be learned from investigations of flare physics at high energies.

  7. Use of simulation in flare countermeasure development

    CSIR Research Space (South Africa)

    Delport, JP

    2008-11-01

    Full Text Available ● Assume enough flare energy ● Questions addressed ● Timing ● Geometry ● Dispense logic ● Obscuration ● Physics based, spectrally correct ● Question addressed ● Flare spectrum ● Environmental influences © CSIR 2008 AOC Conference – 12 November... November 2008 Slide 12 Engagement Scenarios & Simulations ● Aircraft with flares versus missile ● Flight conditions ● Flare dispense logic ● Flare pod placement, angles ● Multitude of simulated launches ● Visualisation...

  8. Building Big Flares: Constraining Generating Processes of Solar Flare Distributions

    Science.gov (United States)

    Wyse Jackson, T.; Kashyap, V.; McKillop, S.

    2015-12-01

    We address mechanisms which seek to explain the observed solar flare distribution, dN/dE ~ E1.8. We have compiled a comprehensive database, from GOES, NOAA, XRT, and AIA data, of solar flares and their characteristics, covering the year 2013. These datasets allow us to probe how stored magnetic energy is released over the course of an active region's evolution. We fit power-laws to flare distributions over various attribute groupings. For instance, we compare flares that occur before and after an active region reaches its maximum area, and show that the corresponding flare distributions are indistinguishable; thus, the processes that lead to magnetic reconnection are similar in both cases. A turnover in the distribution is not detectable at the energies accessible to our study, suggesting that a self-organized critical (SOC) process is a valid mechanism. However, we find changes in the distributions that suggest that the simple picture of an SOC where flares draw energy from an inexhaustible reservoir of stored magnetic energy is incomplete. Following the evolution of the flare distribution over the lifetimes of active regions, we find that the distribution flattens with time, and for larger active regions, and that a single power-law model is insufficient. This implies that flares that occur later in the lifetime of the active region tend towards higher energies. We conclude that the SOC process must have an upper bound. Increasing the scope of the study to include data from other years and more instruments will increase the robustness of these results. This work was supported by the NSF-REU Solar Physics Program at SAO, grant number AGS 1263241, NASA Contract NAS8-03060 to the Chandra X-ray Center and by NASA Hinode/XRT contract NNM07AB07C to SAO

  9. Initial approach to assess lateral buckling behavior: comparison between design and operational condition of offshore pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Familiar Solano, Rafael; Reis Antunes, Bruno; Santos Hansen, Alexandre [PETROBRAS, Rio de Janeiro, (Brazil)

    2010-07-01

    Offshore pipelines can be subject to lateral buckling; some strategies are applied to prevent buckle initiation by monitoring the buckling behaviour. Some pipelines have been modified by PETROBRAS with triggers and sleepers; and distributed buoyancies have been added along the pipeline route. This paper investigated the thermo-mechanical design of the pipeline to avoid buckling and its consequences. Both planned buckles at dual sleepers and at distributed buoyancy modules and unplanned buckles were studied. Comparisons between the results obtained in design with finite element analysis and observed during operation with sidescan images were made. Seven planned buckles and two unplanned buckles were mapped and analyzed. It was found that the maximum stress, strain and fatigue damage at the buckle locations were fairly low. The mapping tests showed that the lengths and amplitudes of the buckles were compatible with lateral buckles in the design of pipelines.

  10. Comparison between initial Magnetized Liner Inertial Fusion experiments and integrated simulations

    Science.gov (United States)

    Sefkow, A. B.; Gomez, M. R.; Geissel, M.; Hahn, K. D.; Hansen, S. B.; Harding, E. C.; Peterson, K. J.; Slutz, S. A.; Koning, J. M.; Marinak, M. M.

    2014-10-01

    The Magnetized Liner Inertial Fusion (MagLIF) approach to ICF has obtained thermonuclear fusion yields using the Z facility. Integrated magnetohydrodynamic simulations provided the design for the first neutron-producing experiments using capabilities that presently exist, and the initial experiments measured stagnation radii rstag < 75 μm, temperatures around 3 keV, and isotropic neutron yields up to YnDD = 2 ×1012 from imploded liners reaching peak velocities around 70 km/s over an implosion time of about 60 ns. We present comparisons between the experimental observables and post-shot degraded integrated simulations. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  11. Could Flaring Stars Change Our Views of Their Planets?

    Science.gov (United States)

    Kohler, Susanna

    2016-12-01

    As the exoplanet count continues to increase, we are making progressively more measurements of exoplanets outer atmospheres through spectroscopy. A new study, however, reveals that these measurements may be influenced by the planets hosts.Spectra From TransitsExoplanet spectra taken as they transit their hosts can tell us about the chemical compositions of their atmospheres. Detailed spectroscopic measurements of planet atmospheres should become even more common with the next generation of missions, such as the James Webb Space Telescope (JWST), or Planetary Transits and Oscillations of Stars (PLATO).But is the spectrum that we measure in the brief moment of a planets transit necessarily representative of its spectrum all of the time? A team of scientists led by Olivia Venot (University of Leuven in Belgium) argue that it might not be, due to the influence of the planets stellar host.Atmospheric composition of a planet before flare impacts (dotted lines), during the steady state reached after a flare impact (dashed lines), and during the steady state reached after a second flare impact (solid lines). [Venot et al. 2016]The team suggests that when a hosts flares impact upon a planets atmosphere (especially likely in the case of active M-dwarfs that commonly harbor planetary systems), this activity may modify the chemical composition of the planets atmosphere. This would in turn alter the spectrum that we measure from the exoplanet.Modeling AtmospheresVenot and collaborators set out to test the effect of stellar flares on exoplanet atmospheres by modeling the atmospheres of two hypothetical planets orbiting the star AD Leo an active and flaring M dwarf located roughly 16 light-years away at two different distances. The team then examined what happened to the atmospheres, and to the resulting spectra that we would observe, when they were hit with a stellar flare typical of AD Leo.The difference in relative absorption between the initial steady-state and the

  12. Observations of electrons from the decay of solar flare neutrons

    CERN Document Server

    Dröge, W; Klecker, B

    1996-01-01

    We have found evidence for fluxes of energetic electrons in interplanetary space on board the ISEE-3 spacecraft which we interpret as the decay products of neutrons generated in a solar flare on 1980 June 21. The decay electrons arrived at the s/c shortly before the electrons from the flare and can be distinguished from the latter by their distinctive energy spectrum. The time profile of the decay electrons is in good agreement with the results from a simulation based on a scattering mean free path derived from a fit to the flare electron data. The comparison with simultaneously observed decay protons and a published direct measurement of high-energy neutrons places important constraints on the parent neutron spectrum.

  13. Homologous flares and the evolution of NOAA Active Region 2372

    Science.gov (United States)

    Strong, K. T.; Smith, J. B., Jr.; Mccabe, M. K.; Machado, M. E.; Saba, J. L. R.; Simnett, G. M.

    1984-01-01

    A detailed record of the evolution of NOAA Active Region 2372 has been compiled by the FBS Homology Study Group. It was one of the most prolific flare-producing regions observed by SMM. The flares occurred in distinct stages which corresponded to particular evolutionary phases in the development of the active region magnetic field. By comparison with a similar but less productive active region, it is found that the activity seems to be related to the magnetic complexity of the region and the amount of shear in the field. Further, the soft X-ray emission in the quiescent active region is related to its flare rate. Within the broader definition of homology adopted, there was a degree of homology between the events within each stage of evolution of AR2372.

  14. Solar Features - Solar Flares - Patrol

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The H-alpha Flare Patrol identifies time periods each day when the sun is being continuously monitored by select ground-based solar observatories.

  15. Initial periodontal screening and radiographic findings - A comparison of two methods to evaluate the periodontal situation

    Directory of Open Access Journals (Sweden)

    Hornecker Else

    2011-01-01

    Full Text Available Abstract Background The periodontal screening index (PSI is an element of the initial dental examination. The PSI provides information on the periodontal situation and allows a first estimation of the treatment required. The dental panoramic tomography (DPT indicates the proximal bone loss, thus also allowing conclusions on the periodontal situation. In this study, the results of both methods in determining the periodontal situation are compared. Methods The clinical examination covered DMF-T, QHI, and PSI scores at four proximal sites per tooth; the examining dentist was unaware of the radiographic finding. Based on the PSI scores, the findings were diagnosed as follows: score 0 - 2 "no periodontitis", score 3 and 4 "periodontitis". Independent of the locality and time of the clinical evaluation, two dentists examined the DPTs of the subjects. The results were classified as follows: no bone loss = "no periodontitis", and bone loss = "periodontitis". Results 112 male subjects (age 18 to 58, Ø 37.7 ± 8 years were examined. Regarding the PSI, 17 subjects were diagnosed "no periodontitis" and 95 subjects "periodontitis". According to the evaluation of the DPTs, 70 subjects were diagnosed "no periodontitis" and 42 "periodontitis". A comparison of both methods revealed that the diagnosis "no periodontitis" corresponded in 17 cases and "periodontitis" in 42 cases (53%. In 47% (53 cases the results were not congruent. The difference between both methods was statistically significant (p Conclusion The present study shows that the initial assessment of the periodontal situation significantly depends on the method of evaluation.

  16. INITIAL COMPARISON OF BASELINE PHYSICAL AND MECHANICAL PROPERTIES FOR THE VHTR CANDIDATE GRAPHITE GRADES

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Mark C

    2014-09-01

    High-purity graphite is the core structural material of choice in the Very High Temperature Reactor (VHTR) design, a graphite-moderated, helium-cooled configuration that is capable of producing thermal energy for power generation as well as process heat for industrial applications that require temperatures higher than the outlet temperatures of present nuclear reactors. The Baseline Graphite Characterization Program is endeavoring to minimize the conservative estimates of as-manufactured mechanical and physical properties in nuclear-grade graphites by providing comprehensive data that captures the level of variation in measured values. In addition to providing a thorough comparison between these values in different graphite grades, the program is also carefully tracking individual specimen source, position, and orientation information in order to provide comparisons both in specific properties and in the associated variability between different lots, different billets, and different positions from within a single billet. This report is a preliminary comparison between each of the grades of graphite that are considered “candidate” grades from four major international graphite producers. These particular grades (NBG-18, NBG-17, PCEA, IG-110, and 2114) are the major focus of the evaluations presently underway on irradiated graphite properties through the series of Advanced Graphite Creep (AGC) experiments. NBG-18, a medium-grain pitch coke graphite from SGL from which billets are formed via vibration molding, was the favored structural material in the pebble-bed configuration. NBG-17 graphite from SGL is essentially NBG-18 with the grain size reduced by a factor of two. PCEA, petroleum coke graphite from GrafTech with a similar grain size to NBG-17, is formed via an extrusion process and was initially considered the favored grade for the prismatic layout. IG-110 and 2114, from Toyo Tanso and Mersen (formerly Carbone Lorraine), respectively, are fine-grain grades

  17. Comparisons of Patient Demographics in Prospective Sports, Shoulder, and National Database Initiatives

    Science.gov (United States)

    Saltzman, Bryan M.; Cvetanovich, Gregory L.; Bohl, Daniel D.; Cole, Brian J.; Bach, Bernard R.; Romeo, Anthony A.

    2016-01-01

    Background: There has been increased emphasis in orthopaedics on high-quality prospective research to provide evidence-based treatment guidelines, particularly in sports medicine/shoulder surgery. The external validity of these studies has not been established, and the generalizability of the results to clinical practice in the United States is unknown. Hypothesis: Comparison of patient demographics in major prospective studies of arthroscopic sports and shoulder surgeries to patients undergoing the same procedures in the National Surgical Quality Improvement Program (NSQIP) database will show substantial differences to question the generalizability and external validity of those studies. Study Design: Cross-sectional study; Level of evidence, 3. Methods: This study utilized patients undergoing arthroscopic anterior cruciate ligament reconstruction (ACLR), meniscectomy (MX), rotator cuff repair (RCR), and shoulder stabilization (SS) from the NSQIP database (2005-2013). Two prospective studies (either randomized controlled trials or, in 1 case, a major cohort study) were identified for each of the 4 procedures for comparison. Demographic variables available for comparison in both the identified prospective studies and the NSQIP included age, sex, and body mass index (BMI). Results: From the NSQIP database, 5576 ACLR patients, 18,882 MX patients, 7282 RCR patients, and 993 SS patients were identified. The comparison clinical studies included cohort sizes as follows: ACLR, n = 121 and 2683; MX, n = 146 and 330; RCR, n = 90 and 103; SS, n = 88 and 196. Age differed significantly between the NSQIP and the patients in 6 of the 8 prospective clinical studies. Sex differed significantly between the NSQIP and the patients in 7 of the 8 prospective clinical studies. BMI differed significantly between the NSQIP and the patients of all 4 of the prospective clinical studies that reported this demographic variable. Conclusion: Significant differences exist for patient age, sex

  18. A swirling flare-related EUV jet

    Science.gov (United States)

    Zhang, Q. M.; Ji, H. S.

    2014-01-01

    Aims: We report our observations of a swirling flare-related extreme-ultraviolet (EUV) jet on 2011 October 15 at the edge of NOAA active region 11314. Methods: We used the multiwavelength observations in the EUV passbands from the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO). We extracted a wide slit along the jet axis and 12 thin slits across its axis to investigate the longitudinal motion and transverse rotation. We also used data from the Extreme-Ultraviolet Imager (EUVI) aboard the Solar TErrestrial RElations Observatory (STEREO) spacecraft to investigate the three-dimensional (3D) structure of the jet. Ground-based Hα images from the El Teide Observatory, a member of the Global Oscillation Network Group (GONG), provide a good opportunity to explore the relationship between the cool surge and the hot jet. Line-of-sight magnetograms from the Helioseismic and Magnetic Imager (HMI) aboard SDO enable us to study the magnetic evolution of the flare/jet event. We carried out potential-field extrapolation to calculate the magnetic configuration associated with the jet. Results: The onset of jet eruption coincided with the start time of the C1.6 flare impulsive phase. The initial velocity and acceleration of the longitudinal motion were 254 ± 10 km s-1 and -97 ± 5 m s-2, respectively. The jet presented helical structure and transverse swirling motion at the beginning of its eruption. The counter-clockwise rotation slowed down from an average velocity of ~122 km s-1 to ~80 km s-1. The interwinding thick threads of the jet untwisted into multiple thin threads during the rotation that lasted for one cycle with a period of ~7 min and an amplitude that increases from ~3.2 Mm at the bottom to ~11 Mm at the upper part. Afterwards, the curtain-like leading edge of the jet continued rising without rotation, leaving a dimming region behind, before falling back to the solar surface. The appearance/disappearance of dimming corresponded to the

  19. Ion energy storage for post-flare loops

    Science.gov (United States)

    Hudson, H. S.

    1985-01-01

    Low-energy non-thermal protons may have long lifetimes in coronal loops with low density and high temperature. If energy were stored in such protons in the initial phases of a solar flare, it could be released slowly during the later phases. Within the present observational limits for post-flare loops, this mechanism should be considered in addition to a field-line reconnection theory of the Kopp and Pneuman type. The thin-target gamma ray emission from the trapped protons is below present limits, but more sensitive observations can test the hypothesis.

  20. Electron Acceleration in Contracting Magnetic Islands during Solar Flares

    Science.gov (United States)

    Borovikov, D.; Tenishev, V.; Gombosi, T. I.; Guidoni, S. E.; DeVore, C. R.; Karpen, J. T.; Antiochos, S. K.

    2017-01-01

    Electron acceleration in solar flares is well known to be efficient at generating energetic particles that produce the observed bremsstrahlung X-ray spectra. One mechanism proposed to explain the observations is electron acceleration within contracting magnetic islands formed by magnetic reconnection in the flare current sheet. In a previous study, a numerical magnetohydrodynamic simulation of an eruptive solar flare was analyzed to estimate the associated electron acceleration due to island contraction. That analysis used a simple analytical model for the island structure and assumed conservation of the adiabatic invariants of particle motion. In this paper, we perform the first-ever rigorous integration of the guiding-center orbits of electrons in a modeled flare. An initially isotropic distribution of particles is seeded in a contracting island from the simulated eruption, and the subsequent evolution of these particles is followed using guiding-center theory. We find that the distribution function becomes increasingly anisotropic over time as the electrons’ energy increases by up to a factor of five, in general agreement with the previous study. In addition, we show that the energized particles are concentrated on the Sunward side of the island, adjacent to the reconnection X-point in the flare current sheet. Furthermore, our analysis demonstrates that the electron energy gain is dominated by betatron acceleration in the compressed, strengthened magnetic field of the contracting island. Fermi acceleration by the shortened field lines of the island also contributes to the energy gain, but it is less effective than the betatron process.

  1. On the Study of Solar Flares with Neutrino Observatories

    CERN Document Server

    ,

    2016-01-01

    Since the end of the eighties, in response to a reported increase of the total neutrino flux in the Homestake experiment in coincidence with solar flares, neutrino detectors have searched for signals of neutrinos associated with solar flare activity. Protons which are accelerated by the magnetic structures of such flares may collide with the solar atmosphere, producing mesons which subsequently decay, resulting in neutrinos at O(MeV-GeV) energies. The study of such neutrinos would provide a new window on the underlying physics of the acceleration process. The sensitivity to solar flares of the IceCube Neutrino Observatory, located at the geographical South Pole, is currently under study. We introduce a new approach for a time profile analysis. This is based on a stacking method of selected solar flares which are likely to be connected with pion production. An initial approach towards a neutrino search using the current IceCube experiment as well as first efforts to improve the detection efficiency in the futu...

  2. Construct and criterion validity of several proposed DAS28-based rheumatoid arthritis flare criteria

    DEFF Research Database (Denmark)

    van der Maas, Aatke; Lie, Elisabeth; Christensen, Robin;

    2013-01-01

    To describe rheumatoid arthritis (RA) worsening that leads to change or re-initiation of treatment, several Disease Activity Score 28 (DAS28)-based flare criteria have been described, but none validated.......To describe rheumatoid arthritis (RA) worsening that leads to change or re-initiation of treatment, several Disease Activity Score 28 (DAS28)-based flare criteria have been described, but none validated....

  3. Comparison of microRNA expression levels between initial and recurrent glioblastoma specimens.

    Science.gov (United States)

    Ilhan-Mutlu, Aysegül; Wöhrer, Adelheid; Berghoff, Anna Sophie; Widhalm, Georg; Marosi, Christine; Wagner, Ludwig; Preusser, Matthias

    2013-05-01

    Glioblastoma is the most frequent primary brain tumour in adults. Recent therapeutic advances increased patient's survival, but tumour recurrence inevitably occurs. The pathobiological mechanisms involved in glioblastoma recurrence are still unclear. MicroRNAs are small RNAs proposed o have important roles for cancer including proliferation, aggressiveness and metastases development. There exist only few data on the involvement of microRNAs in glioblastoma recurrence. We selected the following 7 microRNAs with potential relevance for glioblastoma pathobiology by means of a comprehensive literature search: microRNA-10b, microRNA-21, microRNA-181b, microRNA-181c, microRNA-195, microRNA-221 and microRNA-222. We further selected 15 primary glioblastoma patients, of whom formalin fixed and paraffin embedded tissue (FFPE) of the initial and recurrence surgery were available. All patients had received first line treatment consisting of postoperative combined radiochemotherapy with temozolomide (n = 15). Non-neoplastic brain tissue samples from 3 patients with temporal lobe epilepsy served as control. The expression of the microRNAs were analysed by RT-qPCR. These were correlated with each other and with clinical parameters. All microRNAs showed detectable levels of expressions in glioblastoma group, whereas microRNA-10b was not detectable in epilepsy patients. MicroRNAs except microRNA-21 showed significantly higher levels in epilepsy patients when compared to the levels of first resection of glioblastoma. Comparison of microRNA levels between first and second resections revealed no significant change. Cox regression analyses showed no significant association of microRNA expression levels in the tumor tissue with progression free survival times. Expression levels of microRNA-10b, microRNA-21, microRNA-181b, microRNA-181c, microRNA-195, microRNA-221 and microRNA-222 do not differ significantly between initial and recurrent glioblastoma.

  4. The Flare Irradiance Spectral Model (FISM) and its Contributions to Space Weather Research, the Flare Energy Budget, and Instrument Design

    Science.gov (United States)

    Chamberlin, Phillip

    2008-01-01

    The Flare Irradiance Spectral Model (FISM) is an empirical model of the solar irradiance spectrum from 0.1 to 190 nm at 1 nm spectral resolution and on a 1-minute time cadence. The goal of FISM is to provide accurate solar spectral irradiances over the vacuum ultraviolet (VUV: 0-200 nm) range as input for ionospheric and thermospheric models. The seminar will begin with a brief overview of the FISM model, and also how the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) will contribute to improving FISM. Some current studies will then be presented that use FISM estimations of the solar VUV irradiance to quantify the contributions of the increased irradiance from flares to Earth's increased thermospheric and ionospheric densites. Initial results will also be presented from a study looking at the electron density increases in the Martian atmosphere during a solar flare. Results will also be shown quantifying the VUV contributions to the total flare energy budget for both the impulsive and gradual phases of solar flares. Lastly, an example of how FISM can be used to simplify the design of future solar VUV irradiance instruments will be discussed, using the future NOAA GOES-R Extreme Ultraviolet and X-Ray Sensors (EXIS) space weather instrument.

  5. Gas flare characterisation with Sentinel-3

    Science.gov (United States)

    Caseiro, Alexandre; Kaiser, Johannes W.; Ruecker, Gernot; Tiemann, Joachim; Leimbach, David

    2017-04-01

    Gas Flaring (GF) is the process of burning waste gases at the tip of a stack. It is widely used in the upstream oil and gas industry. It is a contributor to the imbalance of the greenhouse gases (GHG) concentration in the earth's atmosphere, which prompts global warming. Besides GHG, GF also emits black carbon (BC), a known carcinogen and climate active species. At higher latitudes, GF has been estimated as the main input of atmospheric BC, alongside vegetation fires. The consideration of GF as a source to global budgets has been hindered by technical difficulties of in-situ measurements and the inexistence of a systematic reporting system. Remote sensing offers the possibility of a continuous, global and systematic monitoring of GF over extended periods. Being a high temperature process, GF can be detected from space using measurements at appropriate wavelengths. Considering 1800K as a typical GF temperature and Wien's displacement law, the peak emission will be in the short-wave infrared region. This spectral region is observed by two channels (S5 and S6) of the SLSTR instrument aboard ESA's newly launched Sentinel-3 satellite. Because of solar contamination, only night-time observations are used. In order to characterise the identified gas flares in terms of temperature and area, two Planck curves are fitted to SLSTR radiance observations in five spectral channels (S5 through S9, with F1 and F2). In this work, we present the methodology in detail as well as results for known flaring regions around the world. A comparison with VIIRS on Suomi-NPP and with HSRS on TET-1 over known GF locations is also considered.

  6. Quantitative comparison of initial soil erosion processes and runoff generation in Spanish and German vineyards.

    Science.gov (United States)

    Rodrigo Comino, J; Iserloh, T; Lassu, T; Cerdà, A; Keestra, S D; Prosdocimi, M; Brings, C; Marzen, M; Ramos, M C; Senciales, J M; Ruiz Sinoga, J D; Seeger, M; Ries, J B

    2016-09-15

    The aim of this study was to enable a quantitative comparison of initial soil erosion processes in European vineyards using the same methodology and equipment. The study was conducted in four viticultural areas with different characteristics (Valencia and Málaga in Spain, Ruwer-Mosel valley and Saar-Mosel valley in Germany). Old and young vineyards, with conventional and ecological planting and management systems were compared. The same portable rainfall simulator with identical rainfall intensity (40mmh(-1)) and sampling intervals (30min of test duration, collecting the samples at 5-min-intervals) was used over a circular test plot with 0.28m(2). The results of 83 simulations have been analysed and correlation coefficients were calculated for each study area to identify the relationship between environmental plot characteristics, soil texture, soil erosion, runoff and infiltration. The results allow for identification of the main factors related to soil properties, topography and management, which control soil erosion processes in vineyards. The most important factors influencing soil erosion and runoff were the vegetation cover for the ecological German vineyards (with 97.6±8% infiltration coefficients) and stone cover, soil moisture and slope steepness for the conventional land uses.

  7. Global Properties of Solar Flares

    CERN Document Server

    Hudson, Hugh S

    2011-01-01

    This article broadly reviews our knowledge of solar flares. There is a particular focus on their global properties, as opposed to the microphysics such as that needed for magnetic reconnection or particle acceleration as such. Indeed solar flares will always remain in the domain of remote sensing, so we cannot observe the microscales directly and must understand the basic physics entirely via the global properties plus theoretical inference. The global observables include the general energetics -radiation in flares and mass loss in coronal mass ejections (CMEs) - and the formation of different kinds of ejection and global wave disturbance: the type II radio-burst exciter, the Moreton wave, the EIT "wave," and the "sunquake" acoustic waves in the solar interior. Flare radiation and CME kinetic energy can have comparable magnitudes, of order 10^32 erg each for an X-class event, with the bulk of the radiant energy in the visible-UV continuum. We argue that the impulsive phase of the flare dominates the energetic...

  8. Pre-flare coronal dimmings

    CERN Document Server

    Zhang, Q M; Ji, H S

    2016-01-01

    In this paper, we focus on the pre-flare coronal dimmings. We report our multiwavelength observations of the GOES X1.6 solar flare and the accompanying halo CME produced by the eruption of a sigmoidal magnetic flux rope (MFR) in NOAA active region (AR) 12158 on 2014 September 10. The eruption was observed by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamic Observatory (SDO). The photospheric line-of-sight magnetograms were observed by the Helioseismic and Magnetic Imager (HMI) aboard SDO. The soft X-ray (SXR) fluxes were recorded by the GOES spacecraft. The halo CME was observed by the white light coronagraphs of the Large Angle Spectroscopic Coronagraph (LASCO) aboard SOHO.} {About 96 minutes before the onset of flare/CME, narrow pre-flare coronal dimmings appeared at the two ends of the twisted MFR. They extended very slowly with their intensities decreasing with time, while their apparent widths (8$-$9 Mm) nearly kept constant. During the impulsive and decay phases of flare, typical fanlike ...

  9. Cirrus Parcel Model Comparison Project. Phase 1: The Critical Components to Simulate Cirrus Initiation Explicitly.

    Science.gov (United States)

    Lin, Ruei-Fong; O'C. Starr, David; Demott, Paul J.; Cotton, Richard; Sassen, Kenneth; Jensen, Eric; Kärcher, Bernd; Liu, Xiaohong

    2002-08-01

    The Cirrus Parcel Model Comparison Project, a project of the GCSS [Global Energy and Water Cycle Experiment (GEWEX) Cloud System Studies] Working Group on Cirrus Cloud Systems, involves the systematic comparison of current models of ice crystal nucleation and growth for specified, typical, cirrus cloud environments. In Phase 1 of the project reported here, simulated cirrus cloud microphysical properties from seven models are compared for `warm' (40°C) and `cold' (60°C) cirrus, each subject to updrafts of 0.04, 0.2, and 1 m s1. The models employ explicit microphysical schemes wherein the size distribution of each class of particles (aerosols and ice crystals) is resolved into bins or the evolution of each individual particle is traced. Simulations are made including both homogeneous and heterogeneous ice nucleation mechanisms (all-mode simulations). A single initial aerosol population of sulfuric acid particles is prescribed for all simulations. Heterogeneous nucleation is disabled for a second parallel set of simulations in order to isolate the treatment of the homogeneous freezing (of haze droplets) nucleation process. Analysis of these latter simulations is the primary focus of this paper.Qualitative agreement is found for the homogeneous-nucleation-only simulations; for example, the number density of nucleated ice crystals increases with the strength of the prescribed updraft. However, significant quantitative differences are found. Detailed analysis reveals that the homogeneous nucleation rate, haze particle solution concentration, and water vapor uptake rate by ice crystal growth (particularly as controlled by the deposition coefficient) are critical components that lead to differences in the predicted microphysics.Systematic differences exist between results based on a modified classical theory approach and models using an effective freezing temperature approach to the treatment of nucleation. Each method is constrained by critical freezing data from

  10. What's an Asthma Flare-Up?

    Science.gov (United States)

    ... Your 1- to 2-Year-Old What's an Asthma Flare-Up? KidsHealth > For Parents > What's an Asthma ... of a straw that's being pinched. Causes of Asthma Flare-Ups People with asthma have airways that ...

  11. Cycle 23 Variation in Solar Flare Productivity

    CERN Document Server

    Hudson, Hugh; McTiernan, Jim

    2014-01-01

    The NOAA listings of solar flares in cycles 21-24, including the GOES soft X-ray magnitudes, enable a simple determination of the number of flares each flaring active region produces over its lifetime. We have studied this measure of flare productivity over the interval 1975-2012. The annual averages of flare productivity remained approximately constant during cycles 21 and 22, at about two reported M or X flares per region, but then increased significantly in the declining phase of cycle 23 (the years 2004-2005). We have confirmed this by using the independent RHESSI flare catalog to check the NOAA events listings where possible. We note that this measure of solar activity does not correlate with the solar cycle. The anomalous peak in flare productivity immediately preceded the long solar minimum between cycles 23 and 24.

  12. Astrophysics: Unexpected X-ray flares

    Science.gov (United States)

    Campana, Sergio

    2016-10-01

    Two sources of highly energetic flares have been discovered in archival X-ray data of 70 nearby galaxies. These flares have an undetermined origin and might represent previously unknown astrophysical phenomena. See Letter p.356

  13. Chasing White-Light Flares

    Science.gov (United States)

    Hudson, H. S.

    2016-05-01

    In this memoir I describe my life in research, mostly in the area of solar physics. The recurring theme is "white-light flares," and several sections of this paper deal with this and related phenomena; I wind up describing how I see the state of the art in this still-interesting and crucially important (as it has been since 1859) area of flare research. I also describe my participation in two long-lived satellite programs dedicated to solar observations ( Yohkoh and RHESSI) and elaborate on their discoveries. These have both helped with white-light flares both directly and also with closely related X-ray and γ-ray emissions), with the result that this article leans heavily in that direction.

  14. FLARE FLAME INSTABILITY AND BURNER COMBUSTION CONTROL

    OpenAIRE

    БОНДАРЕНКО А.В.; В. Э. Волков; Максимов, М. В.

    2014-01-01

    Research of the flare instability development and the laminar-to-turbulent transition for the flares was executed. It was proved that the effects of viscosity and compressibility have the stabilizing influence on the gas flame. The study of the individual flare stability makes the theoretical basis of the fuel burning technology in combustion chambers and for the burner combustion control.

  15. On Flare Driven Global Waves

    OpenAIRE

    Karoff, C.

    2008-01-01

    We recently presented evidence of a strong correlation between the energy in the high-frequency part of the acoustic spectrum of the Sun and the solar X-ray flux Karoff & Kjeldsen (2008). The discovery indicates that flares drive global oscillations in the Sun in the same way that the entire Earth is set ringing for several weeks after a major earthquake, such as the 2004 December Sumatra-Andaman one. If this indication turns out to be true we might be able to use the relation between flares ...

  16. Instant CloudFlare starter

    CERN Document Server

    Dickey, Jeff

    2013-01-01

    Get to grips with a new technology, understand what it is and what it can do for you, and then get to work with the most important features and tasks. Written as a practical guide, CloudFlare Starter will show you all you need to know in order to effectively improve your online presence in a multitude of different ways. ""Instant CloudFlare Starter"" is a practical yet accessible guide for website owners looking to optimize their site for optimum security and maximum performance.

  17. Construct and criterion validity of several proposed DAS28-based rheumatoid arthritis flare criteria: an OMERACT cohort validation study

    NARCIS (Netherlands)

    Maas, A. van der; Lie, E.; Christensen, R.; Choy, E.; Man, Y.A. de; Riel, P. van; Woodworth, T.; Broeder, A.A. den

    2013-01-01

    BACKGROUND: To describe rheumatoid arthritis (RA) worsening that leads to change or re-initiation of treatment, several Disease Activity Score 28 (DAS28)-based flare criteria have been described, but none validated. METHODS: Six previously published DAS28-based flare criteria ((1) increase in DAS28

  18. Magnetic Energy Release in Solar Flares

    Science.gov (United States)

    Forbes, Terry G.

    2017-01-01

    Solar flares are the result of a rapid release of magnetic energy stored in the solar corona. An ideal-MHD process, such as a loss of magnetic equilibrium, most likely initiates the flare, but the non-ideal process of magnetic reconnection quickly becomes the dominant mechanism by which energy is released. Within the last few years EUV and X-ray instruments have directly observed the kind of plasma flows and heating indicative of magnetic reconnection. Relatively cool plasma is observed moving slowly into the reconnection region where it is transformed into two high-temperature, high-speed outflow jets moving in opposite directions. Observations of the flow in these jets suggest that they are accelerated to the ambient Alfvén speed in a manner that resembles the reconnection process first proposed by H. E. Petschek in 1964. This result is somewhat surprising because Petschek-type reconnection does not occur in most numerical simulations of magnetic reconnection. The apparent contradiction between the observations and the simulations can be understood by the fact that most simulations assume a uniform resistivity model that is unlikely to occur in reality. Recently, we have developed a theory that shows how the type of reconnection is related to the plasma resistivity. The theory is based on a form of the time-dependent, MHD-nozzle equations that incorporate the plasma resistivity. These equations are very similar to the equations used to describe magnetized plasma flow in astrophysical jets.

  19. Reconnection in Solar Flares: Outstanding Questions

    Indian Academy of Sciences (India)

    Hiroaki Isobe; Kazunari Shibata

    2009-06-01

    Space observations of solar flares such as those from Yohkoh, SOHO,TRACE, and RHESSI have revealed a lot of observational evidence of magnetic reconnection in solar flares: cusp-shaped arcades, reconnection inflows, plasmoids, etc. Thus it has been established, at least phenomenologically, that magnetic reconnection does occur in solar flares. However, a number of fundamental questions and puzzles still remain in the physics of reconnection in solar flares. In this paper, we discuss the recent progresses and future prospects in the study of magnetic reconnection in solar flares from both theoretical and observational points of view.

  20. Observed characteristics of flare energy release. I. Magnetic structure at the energy release site

    Energy Technology Data Exchange (ETDEWEB)

    Machado, M.E.; Moore, R.L.; Hagyard, M.J.; Hernandez, A.M.; Rovira, M.G.

    1988-03-01

    It is shown that flaring activity as seen in X-rays usually encompasses two or more interacting magnetic bipoles within an active region. Soft and hard X-ray spatiotemporal evolution is considered as well as the time dependence of the thermal energy content in different magnetic bipoles participating in the flare, the hardness and impulsivity of the hard X-ray emission, and the relationship between the X-ray behavior and the strength and observable shear of the magnetic field. It is found that the basic structure of a flare usually consists of an initiating closed bipole plus one or more adjacent closed bipoles impacted against it. 119 references.

  1. Probabilistic forecasting of solar flares from vector magnetogram data

    Science.gov (United States)

    Barnes, G.; Leka, K. D.; Schumer, E. A.; Della-Rose, D. J.

    2007-09-01

    Discriminant analysis is a statistical approach for assigning a measurement to one of several mutually exclusive groups. Presented here is an application of the approach to solar flare forecasting, adapted to provide the probability that a measurement belongs to either group, the groups in this case being solar active regions which produced a flare within 24 hours and those that remained flare quiet. The technique is demonstrated for a large database of vector magnetic field measurements obtained by the University of Hawai'i Imaging Vector Magnetograph. For a large combination of variables characterizing the photospheric magnetic field, the results are compared to a Bayesian approach for solar flare prediction, and to the method employed by the U.S. Space Environment Center (SEC). Although quantitative comparison is difficult as the present application provides active region (rather than whole-Sun) forecasts, and the present database covers only part of one solar cycle, the performance of the method appears comparable to the other approaches.

  2. Comparison of estimated glomerular filtration rate equations at the time of hemodialysis initiation

    Directory of Open Access Journals (Sweden)

    Min-Jeong Lee

    2015-12-01

    Conclusions: The eGFR at HD initiation are significantly different according to the used eGFR equations, and the corrected Cockcroft–Gault equation may be the best in defining the eGFR at HD initiation.

  3. Flare emission from Sagittarius A*

    CERN Document Server

    Eckart, A; Vogel, S N; Teuben, P; Morris, M R; Baganoff, F; Dexter, J; Schoedel, R; Witzel, G; Valencia-S., M; Karas, V; Kunneriath, D; Bremer, M; Straubmeier, C; Moser, L; Sabha, N; Buchholz, R; Zamaninasab, M; Muzic, K; Moultaka, J; Zensus, J A

    2012-01-01

    Based on Bremer et al. (2011) and Eckart et al. (2012) we report on simultaneous observations and modeling of the millimeter, near-infrared, and X-ray flare emission of the source Sagittarius A* (SgrA*) associated with the super-massive black hole at the Galactic Center. We study physical processes giving rise to the variable emission of SgrA* from the radio to the X-ray domain. To explain the statistics of the observed variability of the (sub-)mm spectrum of SgrA*, we use a sample of simultaneous NIR/X-ray flare peaks and model the flares using a synchrotron and SSC mechanism. The observations reveal flaring activity in all wavelength bands that can be modeled as the signal from adiabatically expanding synchrotron self-Compton (SSC) components. The model parameters suggest that either the adiabatically expanding source components have a bulk motion larger than v_exp or the expanding material contributes to a corona or disk, confined to the immediate surroundings of SgrA*. For the bulk of the synchrotron and ...

  4. The Crab Nebula flaring activity

    Directory of Open Access Journals (Sweden)

    G. Montani

    2014-12-01

    Full Text Available The discovery made by AGILE and Fermi of a short time scale flaring activity in the gamma-ray energy emission of the Crab Nebula is a puzzling and unexpected feature, challenging particle acceleration theory. In the present work we propose the shock-induced magnetic reconnection as a viable mechanism to explain the Crab flares. We postulate that the emitting region is located at ∼1015 cm from the central pulsar, well inside the termination shock, which is exactly the emitting region size as estimated by the overall duration of the phenomenon ∼1 day. We find that this location corresponds to the radial distance at which the shock-induced magnetic reconnection process is able to accelerate the electrons up to a Lorentz factor ∼109, as required by the spectral fit of the observed Crab flare spectrum. The main merit of the present analysis is to highlight the relation between the observational constraints to the flare emission and the radius at which the reconnection can trigger the required Lorentz factor. We also discuss different scenarios that can induce the reconnection. We conclude that the existence of a plasma instability affecting the wind itself as the Weibel instability is the privileged scenario in our framework.

  5. The Crab Nebula flaring activity

    Energy Technology Data Exchange (ETDEWEB)

    Montani, G., E-mail: giovanni.montani@frascati.enea.it [ENEA – C.R, UTFUS-MAG, via Enrico Fermi 45, I-00044 Frascati (RM) (Italy); Dipartimento di Fisica, Università di Roma “Sapienza”, p.le Aldo Moro 5, I-00185 Roma (Italy); Bernardini, M.G. [INAF – Osservatorio Astronomico di Brera, via Bianchi 46, I-23807 Merate (Italy)

    2014-12-12

    The discovery made by AGILE and Fermi of a short time scale flaring activity in the gamma-ray energy emission of the Crab Nebula is a puzzling and unexpected feature, challenging particle acceleration theory. In the present work we propose the shock-induced magnetic reconnection as a viable mechanism to explain the Crab flares. We postulate that the emitting region is located at ∼10{sup 15} cm from the central pulsar, well inside the termination shock, which is exactly the emitting region size as estimated by the overall duration of the phenomenon ∼1 day. We find that this location corresponds to the radial distance at which the shock-induced magnetic reconnection process is able to accelerate the electrons up to a Lorentz factor ∼10{sup 9}, as required by the spectral fit of the observed Crab flare spectrum. The main merit of the present analysis is to highlight the relation between the observational constraints to the flare emission and the radius at which the reconnection can trigger the required Lorentz factor. We also discuss different scenarios that can induce the reconnection. We conclude that the existence of a plasma instability affecting the wind itself as the Weibel instability is the privileged scenario in our framework.

  6. Fast electrons in small solar flares

    Science.gov (United States)

    Lin, R. P.

    1975-01-01

    This review summarizes both the direct spacecraft observations of nonrelativistic solar electrons, and observations of the X-ray and radio emission generated by these particles at the sun and in the interplanetary medium. These observations bear on the basic astrophysical process of particle acceleration in tenuous plasmas. We find that in many small solar flares, the nearly 5-100 keV electrons accelerated during flash phase constitute the bulk of the total flare energy. Thus the basic flare mechanism in these flares essentially converts the available flare energy into fast electrons. These electrons may produce the other flare electromagnetic emissions through their interactions with the solar atmosphere. In large proton flares these electrons may provide the energy to eject material from the sun and to create a shock wave which could accelerate nuclei and electrons to much higher energies.

  7. Model Comparison in Subsurface Science: The DECOVALEX and Sim-SEQ Initiatives (Invited)

    Science.gov (United States)

    Birkholzer, J. T.; Mukhopadhyay, S.; Rutqvist, J.; Tsang, C.

    2013-12-01

    , the DECOVALEX project has played a major role in improving our understanding of coupled THM processes in fractured rock and buffer/backfill materials, a subject of importance to performance assessment of a radioactive waste geologic repository. The second example is the Sim-SEQ project, a relatively recent model comparison initiative addressing multi-phase processes relevant in geologic carbon sequestration. Like DECOVALEX, Sim-SEQ is not about benchmarking, but rather about evaluating model building efforts in a broad and comprehensive sense. In Sim-SEQ, sixteen international modeling teams are building their own models for a specific carbon sequestration site referred to as the Sim-SEQ Study site (the S-3 site). The S-3 site is patterned after the ongoing SECARB Phase III Early Test site in southwestern Mississippi, where CO2 is injected into a fluvial sandstone unit with high vertical and lateral heterogeneity. The complex geology of the S-3 site, its location in the water leg of a CO2-EOR field with a strong water drive, and the presence of methane in the reservoir brine make this a challenging task, requiring the modelers to use their best judgment in making a large number of choices about how to model various processes and properties of the system.

  8. Transition Region Emission and the Energy Input to Thermal Plasma in Solar Flares

    Science.gov (United States)

    Holman, Gordon D.; Holman, Gordon D.; Dennis, Brian R.; Haga, Leah; Raymond, John C.; Panasyuk, Alexander

    2005-01-01

    Understanding the energetics of solar flares depends on obtaining reliable determinations of the energy input to flare plasma. X-ray observations of the thermal bremsstrahlung from hot flare plasma provide temperatures and emission measures which, along with estimates of the plasma volume, allow the energy content of this hot plasma to be computed. However, if thermal energy losses are significant or if significant energy goes directly into cooler plasma, this is only a lower limit on the total energy injected into thermal plasma during the flare. We use SOHO UVCS observations of O VI flare emission scattered by coronal O VI ions to deduce the flare emission at transition region temperatures between 100,000 K and 1 MK for the 2002 July 23 and other flares. We find that the radiated energy at these temperatures significantly increases the deduced energy input to the thermal plasma, but by an amount that is less than the uncertainty in the computed energies. Comparisons of computed thermal and nonthermal electron energies deduced from RHESSI, GOES, and UVCS are shown.

  9. COMPTEL gamma-ray observations of the C4 solar flare on 20 January 2000

    Science.gov (United States)

    Young, C. A.; Arndt, M. B.; Bennett, K.; Connors, A.; Debrunner, H.; Diehl, R.; McConnell, M.; Miller, R. S.; Rank, G.; Ryan, J. M.; Schoenfelder, V.; Winkler, C.

    2001-10-01

    The ``Pre-SMM'' (Vestrand and Miller 1998) picture of gamma-ray line (GRL) flares was that they are relatively rare events. This picture was quickly put in question with the launch of the Solar Maximum Mission (SMM). Over 100 GRL flares were seen with sizes ranging from very large GOES class events (X12) down to moderately small events (M2). It was argued by some (Bai 1986) that this was still consistent with the idea that GRL events are rare. Others, however, argued the opposite (Vestrand 1988; Cliver, Crosby and Dennis 1994), stating that the lower end of this distribution was just a function of SMM's sensitivity. They stated that the launch of the Compton Gamma-ray Observatory (CGRO) would in fact continue this distribution to show even smaller GRL flares. In response to a BACODINE cosmic gamma-ray burst alert, COMPtonTELescope on the CGRO recorded gamma rays above 1 MeV from the C4 flare at 0221 UT 20 January 2000. This event, though at the limits of COMPTEL's sensitivity, clearly shows a nuclear line excess above the continuum. Using new spectroscopy techniques we were able to resolve individual lines. This has allowed us to make a basic comparison of this event with the GRL flare distribution from SMM and also compare this flare with a well-observed large GRL flare seen by OSSE. .

  10. KEPLER FLARES. II. THE TEMPORAL MORPHOLOGY OF WHITE-LIGHT FLARES ON GJ 1243

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, James R. A.; Hawley, Suzanne L.; Johnson, Emily C.; Peraza, Jesus; Jansen, Tiffany C.; Larsen, Daniel M. [Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195 (United States); Hebb, Leslie [Department of Physics, Hobart and William Smith Colleges, 300 Pulteney Street, Geneva, NY 14456 (United States); Wisniewski, John P.; Malatesta, Michael; Keil, Marcus; Silverberg, Steven M.; Scheffler, Matthew S.; Berdis, Jodi R. [HL Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W Brooks Street, Norman, OK 73019 (United States); Kowalski, Adam F. [NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Hilton, Eric J., E-mail: jrad@astro.washington.edu [Universe Sandbox, 911 E. Pike Street #333, Seattle, WA 98122 (United States)

    2014-12-20

    We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from 10{sup 29} to 10{sup 33} erg, are found in 11 months of 1 minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a duration of 50 minutes or greater. The underlying distribution of flare durations for events 10 minutes and longer appears to follow a broken power law. Our results support the idea that sympathetic flaring may be responsible for some complex flare events.

  11. Flux rope, hyperbolic flux tube, and late extreme ultraviolet phases in a non-eruptive circular-ribbon flare

    Science.gov (United States)

    Masson, Sophie; Pariat, Étienne; Valori, Gherardo; Deng, Na; Liu, Chang; Wang, Haimin; Reid, Hamish

    2017-08-01

    Context. The dynamics of ultraviolet (UV) emissions during solar flares provides constraints on the physical mechanisms involved in the trigger and the evolution of flares. In particular it provides some information on the location of the reconnection sites and the associated magnetic fluxes. In this respect, confined flares are far less understood than eruptive flares generating coronal mass ejections. Aims: We present a detailed study of a confined circular flare dynamics associated with three UV late phases in order to understand more precisely which topological elements are present and how they constrain the dynamics of the flare. Methods: We perform a non-linear force-free field extrapolation of the confined flare observed with the Helioseismic and Magnetic Imager (HMI) and Atmospheric Imaging Assembly (AIA) instruments on board Solar Dynamics Observatory (SDO). From the 3D magnetic field we compute the squashing factor and we analyse its distribution. Conjointly, we analyse the AIA extreme ultraviolet (EUV) light curves and images in order to identify the post-flare loops, and their temporal and thermal evolution. By combining the two analyses we are able to propose a detailed scenario that explains the dynamics of the flare. Results: Our topological analysis shows that in addition to a null-point topology with the fan separatrix, the spine lines and its surrounding quasi-separatix layer (QSL) halo (typical for a circular flare), a flux rope and its hyperbolic flux tube (HFT) are enclosed below the null. By comparing the magnetic field topology and the EUV post-flare loops we obtain an almost perfect match between the footpoints of the separatrices and the EUV 1600 Å ribbons and between the HFT field line footpoints and bright spots observed inside the circular ribbons. We show, for the first time in a confined flare, that magnetic reconnection occurred initially at the HFT below the flux rope. Reconnection at the null point between the flux rope and the

  12. Soft X-ray emission in flaring coronal loops

    CERN Document Server

    Pinto, R F; Brun, A S

    2014-01-01

    Solar flares are associated with intense soft X-ray emission generated by the hot flaring plasma in coronal magnetic loops. Kink unstable twisted flux-ropes provide a source of magnetic energy which can be released impulsively and account for the heating of the plasma in flares. We investigate the temporal, spectral and spatial evolution of the properties of the thermal X-ray emission produced in such kink-unstable magnetic flux-ropes using a series of MHD simulations. We deduce emission diagnostics and their temporal evolution and discuss the results of the simulations with respect to observations. The numerical setup used consists of a highly twisted loop embedded in a region of uniform and untwisted background coronal magnetic field. We let the kink instability develop, compute the evolution of the plasma properties in the loop (density, temperature) and deduce the X-ray emission properties of the plasma during the whole flaring episode. During the initial phase of the instability plasma heating is mostly ...

  13. The Problematic High-Energy Flares of 2012 March 7

    Science.gov (United States)

    Ryan, James M.; De Nolfo, Georgia

    2017-08-01

    Two X-class flares occurred on 2012 March 7, an X5.3 and an X1.1. The earlier X5 flare gathered much attention, initiating a powerful and fast CME from the eastern hemisphere. The “forgotten” X1 flare exhibited much smaller CME from the same active region one hour later. However, extended high-energy gamma emission was present for almost the entire day of 2012 March 7. We have resolved the gamma emission into two separate, but overlapping extended occurrences, being from the two sequential X-class flares. We find that the later X1 event was slightly more prolific in gamma emission, mostly due to its duration, despite being much weaker in soft x rays and dynamic coronal activity. We attribute the entirety of the gamma emission from particle precipitation from the footpoints two separate quasi-static large-scale (of order 1 solar radius) coronal loops and not from the associated CMEs. Using constraints from ancillary data, we estimate the bounds in parameter space of the loop sizes and embedded turbulence necessary to accelerate protons and ions to high energies producing the gamma emission.

  14. Evidence for Magnetic Reconnection in Three Homologous Solar Flares Observed by RHESSI

    Science.gov (United States)

    Sui, Lin-Hui; Holman, Gordon D.; Dennis, Brian R.

    2004-01-01

    We present RHESSI observF5oss of three homologous flares, which occurred between April 14 and 16, 2002. We find that the RHESSI images of all three flares at energies between 6 and 25 keV had some common features: (1) A. separate coronal source up to approx. 30 deg. above the flare loop appeared in the early impulsive phase and stayed stationary for several minutes. (2) Before the flare loop moved upward; previously reported by others, the flare loop-top centroid moved downward for 2-4 minutes during the early impulsive phase of the Ears: falling by 13 - 30% of its initial height with a speed between 8 and 23 km/s. We conclude that these features are associated with the formation and development of a current sheet between the loop-top and the coronal source. In the April 14-15 flare, we find that the hard X-ray flux (greater than 25 keV) is correlated with the rate at which the flare loop moves upward, indicating that the faster the loop grows, the faster the reconnection rate, and therefore, the greater the flux of accelerated electrons. Subject headings: Sun: L'iaies-Sun: X-1-ay-s -

  15. High-resolution observations of flare precursors in the low solar atmosphere

    Science.gov (United States)

    Wang, Haimin; Liu, Chang; Ahn, Kwangsu; Xu, Yan; Jing, Ju; Deng, Na; Huang, Nengyi; Liu, Rui; Kusano, Kanya; Fleishman, Gregory D.; Gary, Dale E.; Cao, Wenda

    2017-03-01

    Solar flares are generally believed to be powered by free magnetic energy stored in the corona1, but the build up of coronal energy alone may be insufficient to trigger the flare to occur2. The flare onset mechanism is a critical but poorly understood problem, insights into which could be gained from small-scale energy releases known as precursors. These precursors are observed as small pre-flare brightenings in various wavelengths3-13 and also from certain small-scale magnetic configurations such as opposite-polarity fluxes14-16, where the magnetic orientation of small bipoles is opposite to that of the ambient main polarities. However, high-resolution observations of flare precursors together with the associated photospheric magnetic field dynamics are lacking. Here we study precursors of a flare using the unprecedented spatiotemporal resolution of the 1.6-m New Solar Telescope, complemented by new microwave data. Two episodes of precursor brightenings are initiated at a small-scale magnetic channel17-20 (a form of opposite-polarity flux) with multiple polarity inversions and enhanced magnetic fluxes and currents, lying near the footpoints of sheared magnetic loops. Microwave spectra corroborate that these precursor emissions originate in the atmosphere. These results provide evidence of low-atmospheric small-scale energy release, possibly linked to the onset of the main flare.

  16. The Kepler Catalog of Stellar Flares

    Science.gov (United States)

    Davenport, James R. A.

    2016-09-01

    A homogeneous search for stellar flares has been performed using every available Kepler light curve. An iterative light curve de-trending approach was used to filter out both astrophysical and systematic variability to detect flares. The flare recovery completeness has also been computed throughout each light curve using artificial flare injection tests, and the tools for this work have been made publicly available. The final sample contains 851,168 candidate flare events recovered above the 68% completeness threshold, which were detected from 4041 stars, or 1.9% of the stars in the Kepler database. The average flare energy detected is ˜1035 erg. The net fraction of flare stars increases with g - i color, or decreasing stellar mass. For stars in this sample with previously measured rotation periods, the total relative flare luminosity is compared to the Rossby number. A tentative detection of flare activity saturation for low-mass stars with rapid rotation below a Rossby number of ˜0.03 is found. A power-law decay in flare activity with Rossby number is found with a slope of -1, shallower than typical measurements for X-ray activity decay with Rossby number.

  17. Forecasting Repeat Child Abuse from Initial Social Worker Reports: A Metropolitan and Non-metropolitan Comparison.

    Science.gov (United States)

    Padgitt, Steven; Gibbs, Leonard

    Since the phenomenon of reabuse is postulated as being more probable after initial child abuse than is the probability of an initial abuse and since only modest inquiry has been directed at this phenomenon, research was conducted to answer two questions: Is there patterning to reabuse? And if so, is this different in metro and nonmetro…

  18. The contracting and unshearing motion of flare loops in the X 7.1 flare on 2005 January 20 during its rising phase

    Institute of Scientific and Technical Information of China (English)

    Tuan-Hui Zhou; Jun-Feng Wang; Dong Li; Qi-Wu Song; Victor Melnikov; Hai-Sheng Ji

    2013-01-01

    With the aim of studying the relationship between the relative motions of the loop-top (LT) source and footpoints (FPs) during the rising phase of solar flares,we give a detailed analysis of the X7.1 class flare that occurred on 2005 January 20.The flare was clearly observed by RHESSI,showing a distinct X-ray flaring loop with a bright LT source and two well-defined hard X-ray (HXR) FPs.In particular,we correct the projection effect for the positions of the FPs and magnetic polarity inversion line.We find that:(1) The LT source showed an obvious U-shaped trajectory.The source of the higher energy LT shows a faster downward/upward speed.(2) The evolution of FPs was temporally correlated with that of the LT source.The converging/separating motion of FPs corresponds to the downward/upward motion of the LT source.(3) The initial flare shear of this event is found to be nearly 50 degrees,and it has a fluctuating decrease throughout the contraction phase as well as the expansion phase.(4) Four peaks of the time profile of the unshearing rate are found to be temporally correlated with peaks in the HXR emission flux.This flare supports the overall contraction picture of flares:a descending motion of the LT source,in addition to converging and unshearing motion of FPs.All results indicate that the magnetic field was very highly sheared before the onset of the flare.

  19. X-ray observations of the impulsive phase of solar flares with the Yohkoh satellite

    Science.gov (United States)

    Phillips, Andrew

    This thesis starts with an overview of the physics of the solar corona, concentrating on X-ray emission and the plasma dynamics associated with the impulsive or rise phase of solar flares. The Yohkoh satellite is described, with a section on each major instrument on board. Analysis techniques used in the thesis are then introduced, with a section of soft X-ray spectroscopy and on the application of the Maximum Entropy Method image reconstruction technique to data from the Hard X-ray Telescope on Yohkoh. The instrumental effect known as fixed pattern noise is described, leading to a numerical model of the BCS digitisation process, which is used both to understand the limits of the detector, and to correct the data in a limited way. Alternative methods for the avoidance of fixed pattern noise are evaluated. The analysis of a solar flare with unusually large soft X-ray blue shifts is then performed. Physical parameters of the plasma during the initial stages of the flare are derived, which are used in an energy balance calculation. Agreement is found between the energy in nonthermal electrons and that contained in the coronal plasma, supporting the nonthermal beam driven chromospheric evaporation theory of impulsive flares. The location of superhot plasma in two impulsive flares and one hot thermal flare is then investigated. Superhot plasma is found to be located close to the chromosphere, and related to the nonthermal burst in the two impulsive flares. Superhot plasma in the hot thermal flare is distributed uniformly throughout the loop. The differences are explained as being due to the different energy transport processes active in each type of flare.

  20. Flares of Nearby, Mid-to-late M-dwarfs Characterized by the MEarth Project

    Science.gov (United States)

    Mondrik, Nicholas; Charbonneau, David; Irwin, Jonathan; Newton, Elisabeth R.

    2017-01-01

    Stellar flares are both a curse and a blessing: Transit and radial velocity searches for exoplanets are hindered by the variability caused by flares, while the characteristics of this variability offer valuable insight into the magnetic properties of the star. We present an analysis of flare events of nearby, mid-to-late M-dwarfs from the MEarth Project. MEarth consists of a northern and a southern array of 8 telescopes each that photometrically monitors most mid-to-late M-dwarfs within 30 parsecs. Although the initial motivation was to search for exoplanet transits, the cadence of approximately 20 minutes is well-suited to capturing long-lived flares. However, MEarth employs a single, wide, red bandpass, which poses challenges to the robust detection of flare events, which are typically bluer in color. Using MEarth data, our team has recently published trigonometric parallaxes and estimates of rotation periods for an unprecedented number of nearby low-mass stars. We also gathered supplementary optical and near infrared spectra of a subset of these stars. We describe here the properties of the flares detected by MEarth, and explore the relation of the presence of flares on individual stars with stellar parameters such as rotational period, mass, and H-alpha equivalent width. We also provide an estimate of flare rate for individual stars by injecting flares into our pipeline.The MEarth project acknowledges funding from the National Science Foundation and the David and Lucile Packard Foundation Fellowship for Science and Engineering. This work was made possible through the support of a grant from the John Templeton Foundation.

  1. Pre-Flare Dynamics of Sunspot Groups

    CERN Document Server

    Korsos, M B; Ludmany, A

    2014-01-01

    Several papers provide evidences that the most probable sites of flare onset are the regions of high horizontal magnetic field gradients in solar active regions. Besides the localization of flare producing areas the present work intends to reveal the characteristic temporal variations in these regions prior to flares. This study uses sunspot data instead of magnetograms, it follows the behaviour of a suitable defined proxy measure representing the horizontal magnetic field gradient. The source of the data is the SDD (SOHO/MDI-Debrecen Data) sunspot catalogue. The most promising pre-flare signatures are the following properties of the gradient variation: i) steep increase, ii) high maximum, iii) significant fluctuation and iv) a gradual decrease between the maximum and the flare onset which can be related to the "pull mode" of the current layer. These properties may yield a tool for the assessment of flare probability and intensity within the next 8-10 hours.

  2. Pre-flare dynamics of sunspot groups

    Energy Technology Data Exchange (ETDEWEB)

    Korsós, M. B.; Baranyi, T.; Ludmány, A., E-mail: korsos.marianna@csfk.mta.hu, E-mail: baranyi.tunde@csfk.mta.hu, E-mail: ludmany.andras@csfk.mta.hu [Heliophysical Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, 4010 Debrecen, P.O. Box 30 (Hungary)

    2014-07-10

    Several papers provide evidence that the most probable sites of flare onset are the regions of high horizontal magnetic field gradients in solar active regions. Besides the localization of flare-producing areas, this work intends to reveal the characteristic temporal variations in these regions prior to flares. This study uses sunspot data instead of magnetograms and follows the behavior of a suitable defined proxy measure representing the horizontal magnetic field gradient. The source of the data is the SDD (SOHO/MDI-Debrecen Data) sunspot catalog. The most promising pre-flare signatures are the following properties of gradient variation: (1) steep increase, (2) high maximum, (3) significant fluctuation, and (4) a gradual decrease between the maximum and the flare onset that can be related to the 'pull mode' of the current layer. These properties may yield a tool for the assessment of flare probability and intensity within the following 8-10 hr.

  3. The Acceleration of Ions in Solar Flares During Magnetic Reconnection

    CERN Document Server

    Knizhnik, Kalman; Drake, James F

    2011-01-01

    The acceleration of solar flare ions during magnetic reconnection is explored via particle-in-cell simulations that self-consistently follow the motions of both protons and $\\alpha$ particles. We demonstrate that the dominant ion heating during reconnection with a guide field (a magnetic component perpendicular to the reconnection plane) results from pickup behavior during the entry into reconnection exhausts. In contrast with anti-parallel reconnection, the temperature increment is dominantly transverse, rather than parallel, to the local magnetic field. The comparison of protons and alphas reveals a mass-to-charge ($M/Q$) threshold in pickup behavior that favors heating of high $M/Q$ ions over protons, which is consistent with impulsive flare observations.

  4. Monitoring of FR Cnc Flaring Activity

    CERN Document Server

    Golovin, A; Pavlenko, E; Kuznyetsova, Yu; Krushevska, V; Sergeev, A

    2007-01-01

    Being excited by the detection of the first ever-observed optical flare in FR Cnc, we decided to continue photometrical monitoring of this object. The observations were carried out at Crimean Astrophysical Observatory (Crimea, Ukraine; CrAO - hereafter) and at the Terskol Observatory (Russia, Northern Caucasus). The obtained lightcurves are presented and discussed. No distinguishable flares were detected that could imply that flares on FR Cnc are very rare event.

  5. X-ray Studies of Flaring Plasma

    Indian Academy of Sciences (India)

    B. Sylwester; J. Sylwester; K. J. H. Phillips

    2008-03-01

    We present some methods of X-ray data analysis employed in our laboratory for deducing the physical parameters of flaring plasma. For example, we have used a flare well observed with Polish instrument RESIK aboard Russian CORONAS-F satellite. Based on a careful instrument calibration, the absolute fluxes in a number of individual spectral lines have been obtained. The analysis of these lines allows us to follow the evolution of important thermodynamic parameters characterizing the emitting plasma throughout this flare evolution.

  6. Extreme Ultraviolet Late-Phase Flares: Before and During the Solar Dynamics Observatory Mission

    CERN Document Server

    Woods, Thomas N

    2014-01-01

    The SDO EUV observations have revealed interesting characteristics of warm coronal emissions, which peak soon after the hot coronal X-ray emissions peak during a flare and then sometimes peak for a second time hours after the X-ray flare peak. This flare type, with two warm coronal emission peaks but only one X-ray peak, has been named the EUV late phase. These flares have the distinct properties of i) having a complex magnetic field structure with two initial sets of coronal loops, with one upper set overlaying a lower set, ii) having an eruptive flare initiated in the lower set and disturbing both loop sets, iii) having the hot coronal emissions emitted only from the lower set, and iv) having the first peak of the warm coronal emissions associated with the lower set and its second peak emitted from the upper set much later. The disturbance of the coronal loops by the eruption is at about the same time, but the relaxation and cooling down of the heated coronal loops during the post-flare reconnections have d...

  7. The Statistical Analyses of the White-Light Flares: Two Main Results About Flare Behaviours

    CERN Document Server

    Dal, H A

    2012-01-01

    We present two main results, based on the models and the statistical analyses of 1672 U-band flares. We also discuss the behaviours of the white-light flares. In addition, the parameters of the flares detected from two years of observations on CR Dra are presented. By comparing with the flare parameters obtained from other UV Ceti type stars, we examine the behaviour of optical flare processes along the spectral types. Moreover, we aimed, using large white-light flare data,to analyse the flare time-scales in respect to some results obtained from the X-ray observations. Using the SPSS V17.0 and the GraphPad Prism V5.02 software, the flares detected from CR Dra were modelled with the OPEA function and analysed with t-Test method to compare similar flare events in other stars. In addition, using some regression calculations in order to derive the best histograms, the time-scales of the white-light flares were analysed. Firstly, CR Dra flares have revealed that the white-light flares behave in a similar way as th...

  8. Relationship of Non-potentiality and Flaring: Intercomparison for an M-class Flare

    Indian Academy of Sciences (India)

    Ashok Ambastha; Shibu K. Mathew

    2000-09-01

    We have made an attempt to obtain relationship of magnetic shear and vertical currents in NOAA AR7321. Intercomparison of changes observed at several flaring and non-flaring sites associated with an M4/2B flare observed on October 26, 1992 is reported.

  9. The Kepler Catalog of Stellar Flares

    CERN Document Server

    Davenport, James R A

    2016-01-01

    A homogeneous search for stellar flares has been performed using every available Kepler light curve. An iterative light curve de-trending approach was used to filter out both astrophysical and systematic variability to detect flares. The flare recovery completeness has also been computed throughout each light curve using artificial flare injection tests, and the tools for this work have been made publicly available. The final sample contains 851,168 candidate flare events recovered above the 68% completeness threshold, which were detected from 4041 stars, or 1.9% of the stars in the Kepler database. The average flare energy detected is ~$10^{35}$ erg. The net fraction of flare stars increases with $g-i$ color, or decreasing stellar mass. For stars in this sample with previously measured rotation periods, the total relative flare luminosity is compared to the Rossby number. A tentative detection of flare activity saturation for low-mass stars with rapid rotation below a Rossby number of ~0.03 is found. A power...

  10. Real-world comparison of health care utilization between duloxetine and pregabalin initiators with fibromyalgia

    Directory of Open Access Journals (Sweden)

    Peng X

    2014-01-01

    Full Text Available X Peng,1 P Sun,2 D Novick,1 J Andrews,1 S Sun2 1Eli Lilly and Company, Indianapolis, IN, USA; 2Kailo Research Group, Indianapolis, IN, USA Objectives: To compare health care utilization of duloxetine initiators and pregabalin initiators among fibromyalgia patients in a real-world setting. Methods: A retrospective cohort study was conducted based on a US national commercial health claims database (2006–2009. Fibromyalgia patients who initiated duloxetine or pregabalin in 2008, aged 18–64 years, and who maintained continuous health insurance coverage 1 year before and 1 year after initiation were assigned to duloxetine or pregabalin cohorts on the basis of their initiated agent. Patients who had pill coverage of the agents over the course of 90 days preceding the initiation were excluded. The two comparative cohorts were constructed using propensity score greedy match methods. Descriptive analysis and paired t-test were performed to compare health care utilization rates in the postinitiation year and the changes of these rates from the preinitiation year to the postinitiation year. Results: Both matched cohorts (n=1,265 pairs had a similar mean initiation age (49–50 years, percentage of women (87%–88%, and prevalence of baseline comorbid conditions (neuropathic pain other than diabetic peripheral neuropathic pain, low back pain, cardiovascular disease, hypertension, headache or migraine, and osteoarthritis. In the preinitiation year, both cohorts had similar inpatient, outpatient, and medication utilization rates (inpatient, 15.7%–16.1%; outpatient, 100.0%; medication, 97.9%–98.7%. The utilization rates diverged in the postinitiation year, with the pregabalin cohort using more fibromyalgia-related inpatient care (3.2% versus 2.2%; P<0.05, any inpatient care (19.3% versus 16.8%; P<0.05, and fibromyalgia-related outpatient care (62.1% versus 51.8%; P<0.05. From the preinitiation period to the postinitiation period, the duloxetine cohort

  11. Comparison of initial seed electron generation mechanisms in kinetic simulations of positive streamers

    Science.gov (United States)

    Moore, Christopher; Fierro, Andrew; Jorgenson, Roy; Biedermann, Laura; Clem, Paul; Hjalmarson, Harold; Hopkins, Matthew; Martinez, Raymond

    2016-09-01

    Positive streamer simulations typically resort to initiation by artificially seeding a small region with an initial plasma. However, in order to simulate observed variations in breakdown voltages and times in pulsed voltage experiments, a more physical model for the generation of the initial plasma/electrons is necessary. This work will investigate several models of generating the initial seed plasma in an air-filled gap with a dielectric present: a ``typical'' artificial initial plasma, ionization of the background air due to cosmic rays, field emission from the dielectric, and simulation of radiation incident on surfaces prior to applying the voltage resulting in diffuse e- and O2-densities. 2D axisymmetric PIC-DSMC simulations using a detailed e--air collision model including field-dependent detachment and photon transport will be compared to experiments of an air gap with a dielectric cylinder and a 10 GV/s applied potential. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  12. Comparison of robust H∞ filter and Kalman filter for initial alignment of inertial navigation system

    Institute of Scientific and Technical Information of China (English)

    HAO Yan-ling; CHEN Ming-hui; LI Liang-jun; XU Bo

    2008-01-01

    There are many filtering methods that can be used for the initial alignment of an integrated inertial navigation system.This paper discussed the use of GPS,but focused on two kinds of filters for the initial alignment of an integrated strapdown inertial navigation system (SINS).One method is based on the Kalman filter (KF),and the other is based on the robust filter.Simulation results showed that the filter provides a quick transient response and a little more accurate estimate than KF,given substantial process noise or unknown noise statistics.So the robust filter is an effective and useful method for initial alignment of SINS.This research should make the use of SINS more popular,and is also a step for further research.

  13. Initial Motivations for Teaching: Comparison between Preservice Teachers in the United States and China

    Science.gov (United States)

    Lin, Emily; Shi, Qingmin; Wang, Jian; Zhang, Shaoan; Hui, Liu

    2012-01-01

    This study examined similar and differing initial motivations to teach between 257 US and 542 Chinese preservice teachers using the recently validated FIT-Choice scale. In both countries, participants were motivated to enter teaching because of their social utility values. US preservice teachers reported significantly higher motivations from…

  14. Health workforce responses to global health initiatives funding: a comparison of Malawi and Zambia

    NARCIS (Netherlands)

    R. Brugha; J. Kadzandira; J. Simbaya; P. Dicker; V. Mwapasa; A. Walsh

    2010-01-01

    Background Shortages of health workers are obstacles to utilising global health initiative (GHI) funds effectively in Africa. This paper reports and analyses two countries' health workforce responses during a period of large increases in GHI funds. Methods Health facility record reviews were conduct

  15. Comparison of Initial House Staff Goals with Eventual Career Plans in Internal Medicine

    Science.gov (United States)

    Marienfeld, R. Dennis

    1977-01-01

    This study represents a preliminary effort toward the ultimate goal of identifying some of the major determinants of final career plans of residents in internal medicine. Initial career goal statements indicating future subspecialization are found to be important but the incidence of goal reversal is high. (LBH)

  16. A large-scale search for evidence of quasi-periodic pulsations in solar flares

    CERN Document Server

    Inglis, A R; Dennis, B R; Hayes, L A; Gallagher, P T

    2016-01-01

    The nature of quasi-periodic pulsations in solar flares is poorly constrained, and critically the general prevalence of such signals in solar flares is unknown. Therefore, we perform a large-scale search for evidence of signals consistent with quasi-periodic pulsations in solar flares, focusing on the 1 - 300s timescale. We analyse 675 M- and X-class flares observed by GOES in 1-8\\AA\\ soft X-rays between 2011 February 1 and 2015 December 31. Additionally, over the same era we analyse Fermi/GBM 15-25 keV X-ray data for each of these flares that was associated with a Fermi/GBM solar flare trigger, a total of 261 events. Using a model comparison method, we determine whether there is evidence for a substantial enhancement in the Fourier power spectrum that may be consistent with a QPP signature, based on three tested models; a power-law plus a constant, a broken power-law plus constant, and a power-law-plus-constant with an additional QPP signature component. From this, we determine that ~30% of GOES events and ~...

  17. Fermi-LAT Observations of High-energy Behind-the-limb Solar Flares

    Science.gov (United States)

    Ackermann, M.; Allafort, A.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bonino, R.; Bottacini, E.; Bregeon, J.; Bruel, P.; Buehler, R.; Cameron, R. A.; Caragiulo, M.; Caraveo, P. A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Ciprini, S.; Costanza, F.; Cutini, S.; D’Ammando, F.; de Palma, F.; Desiante, R.; Digel, S. W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Drell, P. S.; Favuzzi, C.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Giglietto, N.; Giordano, F.; Giroletti, M.; Grenier, I. A.; Guillemot, L.; Guiriec, S.; Jogler, T.; Jóhannesson, G.; Kashapova, L.; Krucker, S.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Li, J.; Liu, W.; Longo, F.; Loparco, F.; Lubrano, P.; Magill, J. D.; Maldera, S.; Manfreda, A.; Mazziotta, M. N.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Pal’shin, V.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, O.; Rubio da Costa, F.; Sgrò, C.; Simone, D.; Siskind, E. J.; Spada, F.; Spandre, G.; Spinelli, P.; Tajima, H.; Thayer, J. B.; Torres, D. F.; Troja, E.; Vianello, G.

    2017-02-01

    We report on the Fermi-LAT detection of high-energy emission from the behind-the-limb (BTL) solar flares that occurred on 2013 October 11, and 2014 January 6 and September 1. The Fermi-LAT observations are associated with flares from active regions originating behind both the eastern and western limbs, as determined by STEREO. All three flares are associated with very fast coronal mass ejections (CMEs) and strong solar energetic particle events. We present updated localizations of the >100 MeV photon emission, hard X-ray (HXR) and EUV images, and broadband spectra from 10 keV to 10 GeV, as well as microwave spectra. We also provide a comparison of the BTL flares detected by Fermi-LAT with three on-disk flares and present a study of some of the significant quantities of these flares as an attempt to better understand the acceleration mechanisms at work during these occulted flares. We interpret the HXR emission to be due to electron bremsstrahlung from a coronal thin-target loop top with the accelerated electron spectra steepening at semirelativistic energies. The >100 MeV gamma-rays are best described by a pion-decay model resulting from the interaction of protons (and other ions) in a thick-target photospheric source. The protons are believed to have been accelerated (to energies >10 GeV) in the CME environment and precipitate down to the photosphere from the downstream side of the CME shock and landed on the front side of the Sun, away from the original flare site and the HXR emission.

  18. Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243

    CERN Document Server

    Davenport, James R A; Hebb, Leslie; Wisniewski, John P; Kowalski, Adam F; Johnson, Emily C; Malatesta, Michael; Peraza, Jesus; Keil, Marcus; Silverberg, Steven M; Jansen, Tiffany C; Scheffler, Matthew S; Berdis, Jodi R; Larsen, Daniel M; Hilton, Eric J

    2014-01-01

    We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from $10^{29}$ to $10^{33}$ erg, are found in 11 months of 1-minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a dur...

  19. Prediction of Solar Flare Size and Time-to-Flare Using Support Vector Machine Regression

    CERN Document Server

    Boucheron, Laura E; McAteer, R T James

    2015-01-01

    We study the prediction of solar flare size and time-to-flare using 38 features describing magnetic complexity of the photospheric magnetic field. This work uses support vector regression to formulate a mapping from the 38-dimensional feature space to a continuous-valued label vector representing flare size or time-to-flare. When we consider flaring regions only, we find an average error in estimating flare size of approximately half a \\emph{geostationary operational environmental satellite} (\\emph{GOES}) class. When we additionally consider non-flaring regions, we find an increased average error of approximately 3/4 a \\emph{GOES} class. We also consider thresholding the regressed flare size for the experiment containing both flaring and non-flaring regions and find a true positive rate of 0.69 and a true negative rate of 0.86 for flare prediction. The results for both of these size regression experiments are consistent across a wide range of predictive time windows, indicating that the magnetic complexity fe...

  20. Analysis of infilled beams using method of initial functions and comparison with FEM

    Directory of Open Access Journals (Sweden)

    Rakesh Patel

    2014-09-01

    Full Text Available This paper presents a study carried out on reinforced concrete infilled beams. In reinforced concrete beams, less stressed concrete near neutral axis can be replaced by some light weight material like bricks to reduce the weight of the structure and also achieve the economy. Infilled zone is obtained with the help of stress block diagram, used for limit state design of reinforced concrete beams as per IS 456. Method of initial functions is used for the analysis of infilled reinforced concrete composite beams. The method of initial function (MIF is an analytical method of elasticity theory. The results obtained by MIF are compared with those predicting by Finite Element Method (FEM based software ANSYS, and it is observed that they are comparable.

  1. Temperature comparison of initial, middle and final point of polypropylene friction stir welded

    Science.gov (United States)

    Kusharjanta, Bambang; Raharjo, Wahyu P.; Triyono

    2016-03-01

    Friction Stir Welding is known as a new solid state joining process. This process is applied in thermoplastic polymers material recently. One of member thermoplastic polymer is polypropylene. Polypropylene sheet 6 mm thick was friction stir welded with a cone cut steel pin. Tool rotation, travelling speed, and plunge depth, as welding parameters were 620 rpm, 7.3 mm/minutes and 0.02 mm respectively. Temperature at the initial, middle, and final point of advance side working piece were measured and compared. Measurement were done by thermocouple and recorded by data acquisition. Based on this research, it is concluded that temperature at the initial, middle and final point of friction stir welding process are different. The highest temperature peak reach at the middle point on the advance side which affects face bending strength.

  2. Initial periodontal screening and radiographic findings - A comparison of two methods to evaluate the periodontal situation

    OpenAIRE

    Hornecker Else; Rinke Sven; Szabadi Ivette; Ziebolz Dirk; Mausberg Rainer F

    2011-01-01

    Abstract Background The periodontal screening index (PSI) is an element of the initial dental examination. The PSI provides information on the periodontal situation and allows a first estimation of the treatment required. The dental panoramic tomography (DPT) indicates the proximal bone loss, thus also allowing conclusions on the periodontal situation. In this study, the results of both methods in determining the periodontal situation are compared. Methods The clinical examination covered DMF...

  3. Offshore production flares: a PETROBRAS review

    Energy Technology Data Exchange (ETDEWEB)

    Pagot, Paulo R.; Burmann, Clovis P.; Araujo, Paulo Bento de; Motomura, Tsukasa [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The purpose of the present work is to briefly present the offshore flare system technological evolution and the main design criteria for flare and its supporting structure. In order to perform the aimed task, this work was divided into two parts: the first part presents the technological evolution of the offshore production flares and the second one discusses the flare system designing criteria. The evolution of the technology associated to the offshore production flares is organized by the authors just dividing the history in four chronological phases. Each phase is defined by the predominant use of the, by the time, most up-to-date technological alternative and it will be described with the help of sketches, drawings, photographs, data and information about the platforms where such technologies were applied. The second part of the present work discusses the dimensional criteria, interesting aspects and flaws of the offshore flare systems in two different fields, which are: definition of the flare system capacity; and flow and thermal design of the flare system. (author)

  4. Excitation of XUV radiation in solar flares

    Science.gov (United States)

    Emslie, A. Gordon

    1992-01-01

    The goal of the proposed research was to understand the means by which XUV radiation in solar flares is excited, and to use this radiation as diagnostics of the energy release and transport processes occurring in the flare. Significant progress in both of these areas, as described, was made.

  5. Shock Versus Solar Flare Production of Heliospheric Relativistic Electron Events

    Science.gov (United States)

    Kahler, S. W.; Cliver, E. W.

    2006-12-01

    Electrons with relativistic (E > 0.3 MeV) energies are often observed as discrete events in the inner heliosphere. Their sharp onsets and antisunward flows indicate that they are produced in solar transient events. In general their origins can be associated in time with both solar flares and coronal mass ejections (CMEs). Unlike the solar energetic proton (SEP) and ion events, we do not have the advantage of particle elemental abundances and charge states as source diagnostics. We review the characteristics of the electron events observed on the Helios, Venera, ISEE-3, Phobos, and other inner heliospheric spacecraft to determine whether they are more likely to be produced by broad coronal shocks driven by CMEs or by solar flare processes associated with magnetic reconnection. Electron intensity-time profiles and energy spectra are compared with properties of flares and CMEs for this determination. Recent comparisons of peak electron and SEP event intensities provide strong evidence for the shock interpretation, but definitive results require the observations provided by the Sentinels mission.

  6. Flare Ribbon Expansion and Energy Release

    Indian Academy of Sciences (India)

    Ayumi Asai; Takaaki Yokoyama; Masumi Shimojo; Satoshi Masuda; Kazunari Shibata

    2006-06-01

    We report a detailed examination about the relationship between the evolution of the H flare ribbons and the released magnetic energy during the April 10 2001 flare. In the H images, several bright kernels are observed in the flare ribbons. We identified the conjugated footpoints, by analyzing the lightcurves at each H kernels, and showed their connectivities during the flare. Then, based on the magnetic reconnection model, we calculated quantitatively the released energy by using the photospheric magnetic field strengths and separation speeds of the H flare ribbons. Finally, we examined the downward motions which are observed at the H kernels. We found that the stronger the red-asymmetry tends to be associated with the brighter the H kernel.

  7. The local Poisson hypothesis for solar flares

    CERN Document Server

    Wheatland, M S

    2001-01-01

    The question of whether flares occur as a Poisson process has important consequences for flare physics. Recently Lepreti et al. presented evidence for local departure from Poisson statistics in the Geostationary Operational Environmental Satellite (GOES) X-ray flare catalog. Here it is argued that this effect arises from a selection effect inherent in the soft X-ray observations; namely that the slow decay of enhanced flux following a large flare makes detection of subsequent flares less likely. It is also shown that the power-law tail of the GOES waiting-time distribution varies with the solar cycle. This counts against any intrinsic significance to the appearance of a power law, or to the value of its index.

  8. Stereoscopic Observation of Slipping Reconnection in A Double Candle-Flame-Shaped Solar Flare

    CERN Document Server

    Gou, Tingyu; Wang, Yuming; Liu, Kai; Zhuang, Bin; Chen, Jun; Zhang, Quanhao; Liu, Jiajia

    2016-01-01

    The 2011 January 28 M1.4 flare exhibits two side-by-side candle-flame-shaped flare loop systems underneath a larger cusp-shaped structure during the decay phase, as observed at the northwestern solar limb by the Solar Dynamics Observatory (SDO). The northern loop system brightens following the initiation of the flare within the southern loop system, but all three cusp-shaped structures are characterized by ~ 10 MK temperatures, hotter than the arch-shaped loops underneath. The "Ahead" satellite of the Solar Terrestrial Relations Observatory (STEREO) provides a top view, in which the post-flare loops brighten sequentially, with one end fixed while the other apparently slipping eastward. By performing stereoscopic reconstruction of the post-flare loops in EUV and mapping out magnetic connectivities, we found that the footpoints of the post-flare loops are slipping along the footprint of a hyperbolic flux tube (HFT) separating the two loop systems, and that the reconstructed loops share similarity with the magne...

  9. Chromospheric Condensation and Quasi-periodic Pulsations in a Circular-ribbon Flare

    CERN Document Server

    Zhang, Q M; Ning, Z J

    2016-01-01

    In this paper, we report our multiwavelength observations of the C3.1 circular-ribbon flare SOL2015-10-16T10:20 in AR 12434. The flare consisted of a circular flare ribbon (CFR), an inner flare ribbon (IFR) inside, and a pair of short parallel flare ribbons (PFRs). During the impulsive phase of the flare, "two-step" raster observations of \\textit{IRIS} with a cadence of 6 s and an exposure time of 2 s show plasma downflow at the CFR in the Si {\\sc iv} $\\lambda$1402.77 line, suggesting chromospheric condensation. The downflow speeds first increased rapidly from a few km s$^{-1}$ to the peak values of 45$-$52 km s$^{-1}$, before decreasing gradually to the initial levels. The decay timescales of condensation were 3$-$4 minutes, indicating ongoing magnetic reconnection. Interestingly, the downflow speeds are positively correlated with logarithm of the Si {\\sc iv} line intensity and time derivative of the \\textit{GOES} soft X-ray (SXR) flux in 1$-$8 {\\AA}. The radio dynamic spectra are characterized by a type \\Rm...

  10. A Systematic Chandra study of Sgr A$^{\\star}$: I. X-ray flare detection

    CERN Document Server

    Yuan, Qiang

    2016-01-01

    Daily X-ray flaring represents an enigmatic phenomenon of Sgr A$^{\\star}$ --- the supermassive black hole at the center of our Galaxy. We report initial results from a systematic X-ray study of this phenomenon, based on extensive {\\it Chandra} observations obtained from 1999 to 2012, totaling about 4.5 Ms. We detect flares, using a combination of the maximum likelihood and Markov Chain Monte Carlo methods, which allow for a direct accounting for the pile-up effect in the modeling of the flare lightcurves and an optimal use of the data, as well as the measurements of flare parameters, including their uncertainties. A total of 82 flares are detected. About one third of them are relatively faint, which were not detected previously. The observation-to-observation variation of the quiescent emission has an average root-mean-square of $6\\%-14\\%$, including the Poisson statistical fluctuation of faint flares below our detection limits. We find no significant long-term variation in the quiescent emission and the flar...

  11. Assessment of pulmonary parenchyma perfusion with FAIR in comparison with DCE-MRI-Initial results

    Energy Technology Data Exchange (ETDEWEB)

    Fan Li [Department of Radiology, ChangZheng Hospital Affiliated to Second Military Medical University, No. 415 Fengyang Road, Shanghai 200003 (China)], E-mail: fanli0930@163.com; Liu Shiyuan [Department of Radiology, ChangZheng Hospital Affiliated to Second Military Medical University, No. 415 Fengyang Road, Shanghai 200003 (China); Sun Fei [GE Healthcare China (China)], E-mail: Fei.sun@med.ge.com; Xiao Xiangsheng [Department of Radiology, ChangZheng Hospital Affiliated to Second Military Medical University, No. 415 Fengyang Road, Shanghai 200003 (China)], E-mail: lizhaobin79@163.com

    2009-04-15

    Objective: The aim of this study was to assess pulmonary parenchyma perfusion with flow-sensitive alternating inversion recovery (FAIR) in comparison with 3D dynamic contrast-enhanced (DCE) imaging in healthy volunteers and in patients with pulmonary embolism or lung cancer. Materials and methods: Sixteen healthy volunteers and 16 patients with pulmonary embolism (5 cases) or lung cancer (11 cases) were included in this study. Firstly, the optimized inversion time of FAIR (TI) was determined in 12 healthy volunteers. Then, FAIR imaging with the optimized TI was performed followed by DCE-MRI on the other 4 healthy volunteers and 16 patients. Tagging efficiency of lung and SNR of perfusion images were calculated with different TI values. In the comparison of FAIR with DCE-MRI, the homogeneity of FAIR and DCE-MRI perfusion was assessed. In the cases of perfusion abnormality, the contrast between normal lung and perfusion defects was quantified by calculating a normalized signal intensity ratio. Results: One thousand milliseconds was the optimal TI, which generated the highest lung tagging efficiency and second highest PBF SNR. In the volunteers, the signal intensity of perfusion images acquired with both FAIR and DCE-MRI was homogeneous. Wedged-shaped or triangle perfusion defects were visualized in five pulmonary embolisms and three lung cancer cases. There was no significant statistical difference in signal intensity ratio between FAIR and DCE-MRI (P > 0.05). In the rest of eight lung cancers, all the lesions showed low perfusion against the higher perfused pulmonary parenchyma in both FAIR and DCE-MRI. Conclusion: Pulmonary parenchyma perfusion imaging with FAIR was feasible, consistent and could obtain similar functional information to that from DCE-MRI.

  12. Initial Comparisons between the Advanced Technology Development Gen 2 Baseline Cells and Variant C Cells

    Energy Technology Data Exchange (ETDEWEB)

    Christophersen, Jon Petter; Motloch, Chester George; Wright, Randy Ben; Murphy, Timothy Collins; Belt, Jeffrey R; Ho, Chinh Dac; Bloom, Ira D.; Jones, S. A.; Battaglia, Vincent S.; Jungst, Rudy G.; Case, Herb L.; Sutula, Raymond A.; Barnes, James A.; Duong, Tien Q.

    2002-06-01

    The Advanced Technology Development Program is testing a second generation of lithium-ion cells, consisting of a baseline and three variant chemistries. The cathode composition of the Variant C chemistry was altered with an increase to the aluminum dopant and a decrease to the cobalt dopant to explore the impact on performance. However, it resulted in a 20% drop in rated capacity. Also, the Variant C average power fade is higher, but capacity fade is higher for the Baseline cell chemistry. Initial results indicate that the Variant C chemistry will reach end of life sooner than the Baseline chemistry.

  13. Efficacy of radiofrequency ablation for initial recurrent hepatocellular carcinoma after curative treatment: Comparison with primary cases

    Energy Technology Data Exchange (ETDEWEB)

    Fukuhara, Takayuki; Aikata, Hiroshi, E-mail: aikata@hiroshima-u.ac.jp; Hyogo, Hideyuki; Honda, Yohji; Morio, Kei; Morio, Reona; Hatooka, Masahiro; Kobayashi, Tomoki; Naeshiro, Noriaki; Kawaoka, Tomokazu; Tsuge, Masataka; Hiramatsu, Akira; Imamura, Michio; Kawakami, Yoshiiku; Chayama, Kazuaki

    2015-08-15

    Highlights: • We compared clinical and outcome factors after RFA treatment between primary HCC and recurrent HCC. • Local tumor control and OS are similar, but DFS was significantly shorter in the recurrent group. • RFA is an effective and safe treatment option for initial recurrent small HCC. - Abstract: Objective: To determine the efficacy of radiofrequency ablation (RFA) for initial recurrence of small hepatocellular carcinoma (HCC; ≤3 nodules, each nodule ≤3 cm in diameter) after curative treatment and identify prognostic factors affecting therapeutic outcome, we compared clinical and outcome factors between patients with primary HCC and those with initial recurrent HCC who underwent RFA. Methods: In this retrospective cohort study, 211 HCC patients who underwent RFA were enrolled and comprised two groups: primary group (n = 139) and initial recurrent group (n = 72). We compared local tumor progression, overall survival (OS), disease-free survival (DFS), and RFA safety between the groups. Results: Median follow-up was 53 months. Local tumor progression rate was 5.8% in the primary group and 4.2% in the recurrent group. OS rates at 5 years and 10 years were 63.2% and 25.5% in the primary group and 54.5% and 33.4% in the recurrent group, respectively. Corresponding DFS rates were 30.7% and 14.6% and 19.2% and 11.0%. DFS was significantly shorter in the recurrent group (hazard ratio [HR] = 1.81; 95% confidence interval [CI], 1.27–2.57; P = 0.001). In the recurrent group, time from primary HCC development to recurrence was a determinant of OS (≤2 years; HR = 3.42; 95% CI, 1.52–7.72; P = 0.003). Conclusion: Although local tumor control and OS were similar between the groups, the recurrent group had shorter DFS than the primary group. Time from primary HCC development to recurrence was a prognostic factor for recurrence of HCC.

  14. Whether solar flares can trigger earthquakes?

    Science.gov (United States)

    Jain, R.

    2007-05-01

    We present the study of 682 earthquakes of ¡Ý4.0 magnitude observed during January 1991 to January 2007 in the light of solar flares observed by GOES and SOXS missions in order to explore the possibility of any association between solar flares and earthquakes. Our investigation preliminarily shows that each earthquake under study was preceded by a solar flare of GOES importance B to X class by 10-100 hrs. However, each flare was not found followed by earthquake of magnitude ¡Ý4.0. We classified the earthquake events with respect to their magnitude and further attempted to look for their correlation with GOES importance class and delay time. We found that with the increasing importance of flares the delay in the onset of earthquake reduces. The critical X-ray intensity of the flare to be associated with earthquake is found to be ~10-6 Watts/m2. On the other hand no clear evidence could be established that higher importance flares precede high magnitude earthquakes. Our detailed study of 50 earthquakes associated with solar flares observed by SOXS mission and other wavebands revealed many interesting results such as the location of the flare on the Sun and the delay time in the earthquake and its magnitude. We propose a model explaining the charged particles accelerated during the solar flare and released in the space that undergone further acceleration by interplanetary shocks and produce the ring current in the earth's magnetosphere, which may enhance the process of tectonics plates motion abruptly at fault zones. It is further proposed that such sudden enhancement in the process of tectonic motion of plates in fault zones may increase abruptly the heat gradients on spatial (dT/dx) and temporal (dT/dt) scales responsible for earthquakes.

  15. The diagnostic utility of the flare phenomenon on bone scintigraphy in staging prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Cook, Gary J.R.; Lewington, Valerie J.; Chua, Sue C. [Royal Marsden Hospital, Department of Nuclear Medicine and PET, Sutton, Surrey (United Kingdom); Venkitaraman, Ram; Huddart, Robert A.; Parker, Christopher C.; Dearnaley, David D.; Horwich, Alan [Royal Marsden Hospital, Academic Urology Unit, Sutton, Surrey (United Kingdom); Sohaib, Aslam S. [Royal Marsden Hospital, Department of Radiology, Sutton, Surrey (United Kingdom)

    2011-01-15

    Bone scintigraphy (BS) lacks sensitivity for detecting very early skeletal metastases (SM) in prostate cancer (PC) and is often limited by poor specificity. Also scintigraphic flare of SM can occur following effective treatment and mislead an early response assessment. We hypothesised that a flare reaction might amplify the signal from subclinical SM, increasing the sensitivity of BS and that the phenomenon may be specific for metastases. We conducted a prospective study to determine the frequency of the flare phenomenon in patients with metastatic PC starting hormone therapy and to explore its utility in patients with negative staging scans but considered at high risk of SM and in those with equivocal baseline BS abnormalities. Ninety-nine patients commencing first-line hormone therapy had repeat BS at 6 weeks to score a flare reaction. Of 22 patients with unequivocal SM on the baseline scan, a flare occurred in 9 (41%). Of 36 high-risk localised prostate cancer patients with normal BS pre-treatment, the scan became positive for metastases at 6 weeks in 4 (11%). Of 41 patients with pre-treatment scintigraphic abnormalities of uncertain aetiology, a flare occurred in 8 cases (20%). All eight were confirmed to have SM by follow-up and imaging. Of the 33 remaining patients without a flare, 2 developed SM at 14 months and the remainder did not develop SM in a median follow-up period of 36 months. The flare phenomenon following initial hormone therapy can be used to improve both sensitivity and specificity of BS in PC. (orig.)

  16. Giant Flare in SGR 1806-20 and Its Compton Reflection from the Moon

    CERN Document Server

    Frederiks, D D; Palshin, V D; Aptekar, R L; Ilyinskii, V N; Oleinik, F P; Mazets, E P; Cline, T L

    2007-01-01

    We analyze the data obtained when the Konus-Wind gamma-ray spectrometer detected a giant flare in SGR 1806-20 on December 27, 2004. The flare is similar in appearance to the two known flares in SGR 0526-66 and SGR 1900+14 while exceeding them significantly in intensity. The enormous X-ray and gamma-ray flux in the narrow initial pulse of the flare leads to almost instantaneous deep saturation of the gamma-ray detectors, ruling out the possibility of directly measuring the intensity, time profile, and energy spectrum of the initial pulse. In this situation, the detection of an attenuated signal of Compton back-scattering of the initial pulse emission by the Moon with the Helicon gamma-ray spectrometer onboard the Coronas-F satellite was an extremely favorable circumstance. Analysis of this signal has yielded the most reliable temporal, energy, and spectral characteristics of the pulse. The temporal and spectral characteristics of the pulsating flare tail have been determined from Konus-Wind data. Its soft spec...

  17. A comparison of medium-term survival between peritoneal dialysis and haemodialysis in accordance with the initial vascular access.

    Science.gov (United States)

    García-Cantón, César; Rufino-Hernández, Juana M; Vega-Díaz, Nicanor; Pérez-Borges, Patricia; Bosch-Benítez-Parodi, Elvira; Saavedra, Pedro; García-Gómez, Carolina; Marrero-Robayna, Silvia; Maceira-Cruz, Benito; Rodríguez-Pérez, José C; Checa-Andrés, M Dolores

    2013-01-01

    A study published in 2011 showed that patients in the Canary Islands, who were incident in peritoneal dialysis (PD) had better survival than those who were incident in hemodialysis (HD). Since initiating hemodialysis with central venous catheter is associated with worse prognosis, it would be possible that the initial vascular access influences the results of survival comparison between both groups. To conduct a comparative medium-term survival study of patients incident in renal replacement therapy with different modalities in our community, classifying those incident in hemodialysis according to the initial vascular access: established arteriovenous vascular access or central venous catheter. Retrospective longitudinal cohort study including all patients who were incident in renal replacement therapy between January 2005 and December 2010, with follow-up until December 2011, in three large hospitals of the Canary Islands. Patients were classified according to the initial modality: PD, HD with established vascular access (HD-FAV) or HD with central venous catheter (HD-Cat). Kaplan-Meier survival curves were estimated for each group and a Cox proportional hazards survival model was used to estimate relative mortality risk for DP as compared to HD-FAV and HD-Cat, adjusting for age and Charlson comorbidity index. An equivalent analysis was then conducted on subgroups defined by age or by the presence of diabetes. 1110 patients were included, with a median age of 63 years, 56% of them were diabetic. A Kaplan-Meier analysis showed better survival for PD (66 months) as compared to HD-Cat (41 months), Log Rank pcatheter, while no differences were found between PD and HD with established vascular access. These results could suggest that patients in our community, for whom a vascular access cannot be achieved in predialysis, could have better survival if PD is offered as initial technique, at least until a vascular access is available.

  18. Corporate responsibility reporting according to Global Reporting Initiative: an international comparison

    Directory of Open Access Journals (Sweden)

    Ionela-Corina CHERSAN

    2016-04-01

    Full Text Available The Global Reporting Initiative (GRI is an organization that has managed to impose its reporting practices on corporate responsibility among large transnational companies. The model proposed by GRI is based on the supposed convergence between the economic, social and environmental dimensions of sustainable development. This convergence can be presumed at macroeconomic level, but at the level of enterprises, the three dimensions are often divergent. By analyzing the structure of reports included in the GRI database, our article aims to identify the factors that impact on company’s behavior in the corporate responsibility reporting process. In addition, our research invites to answer the following question: is it not possible that these reports attempt to exaggerate company environmental and social performance, rather than to cause a change in their conduct?

  19. FUV Continuum in Flare Kernels Observed by IRIS

    Science.gov (United States)

    Daw, Adrian N.; Kowalski, Adam; Allred, Joel C.; Cauzzi, Gianna

    2016-05-01

    Fits to Interface Region Imaging Spectrograph (IRIS) spectra observed from bright kernels during the impulsive phase of solar flares are providing long-sought constraints on the UV/white-light continuum emission. Results of fits of continua plus numerous atomic and molecular emission lines to IRIS far ultraviolet (FUV) spectra of bright kernels are presented. Constraints on beam energy and cross sectional area are provided by cotemporaneous RHESSI, FERMI, ROSA/DST, IRIS slit-jaw and SDO/AIA observations, allowing for comparison of the observed IRIS continuum to calculations of non-thermal electron beam heating using the RADYN radiative-hydrodynamic loop model.

  20. Identifying core domains to assess flare in rheumatoid arthritis

    DEFF Research Database (Denmark)

    Bartlett, Susan J; Hewlett, Sarah; Bingham, Clifton O

    2012-01-01

    For rheumatoid arthritis (RA), there is no consensus on how to define and assess flare. Variability in flare definitions impairs understanding of findings across studies and limits ability to pool results. The OMERACT RA Flare Group sought to identify domains to define RA flares from patient...

  1. DISCOVER-AQ: An Overview and Initial Comparisons of NO2 with OMI Observations

    Science.gov (United States)

    Pickering, Kenneth; Crawford, James; Krotkov, Nickolay; Bucsela, Eric; Lamsal, Lok; Celarier, Edward; Herman, Jay; Janz, Scott; Cohen, Ron; Weinheimer, Andrew

    2011-01-01

    The first deployment of the Earth Venture -1 DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project was conducted during July 2011 in the Baltimore-Washington region. Two aircraft (a P-3B for in-situ sampling and a King Air for remote sensing) were used along with an extensive array of surface-based in-situ and remote sensing instrumentation. Fourteen flight days were accomplished by both aircraft and over 250 profiles of trace gases and aerosols were performed by the P-3B over surface air quality monitoring stations, which were specially outfitted with sunphotometers and Pandora UV/Vis spectrometers. The King Air flew with the High Spectral Resolution Lidar for aerosols and the ACAM UV/Vis spectrometer for trace gases. This suite of observations allows linkage of surface air quality with the vertical distributions of gases and aerosols, with remotely-sensed column amounts observed from the surface and from the King Air, and with satellite observations from Aura (OMI and TES), GOME-2, MODIS and GOES. The DISCOVER-AQ data will allow determination of under what conditions satellite retrievals are indicative of surface air quality, and they will be useful in planning new satellites. In addition to an overview of the project, a preliminary comparison of tropospheric column NO2 densities from the integration of in-situ P-3B observations, from the Pandoras and ACAM, and from the new Goddard OMI NO2 algorithm will be presented.

  2. Comparison of Crack Initiation, Propagation and Coalescence Behavior of Concrete and Rock Materials

    Science.gov (United States)

    Zengin, Enes; Abiddin Erguler, Zeynal

    2017-04-01

    There are many previously studies carried out to identify crack initiation, propagation and coalescence behavior of different type of rocks. Most of these studies aimed to understand and predict the probable instabilities on different engineering structures such as mining galleries or tunnels. For this purpose, in these studies relatively smaller natural rock and synthetic rock-like models were prepared and then the required laboratory tests were performed to obtain their strength parameters. By using results provided from these models, researchers predicted the rock mass behavior under different conditions. However, in the most of these studies, rock materials and models were considered as contains none or very few discontinuities and structural flaws. It is well known that rock masses naturally are extremely complex with respect to their discontinuities conditions and thus it is sometimes very difficult to understand and model their physical and mechanical behavior. In addition, some vuggy rock materials such as basalts and limestones also contain voids and gaps having various geometric properties. Providing that the failure behavior of these type of rocks controlled by the crack initiation, propagation and coalescence formed from their natural voids and gaps, the effect of these voids and gaps over failure behavior of rocks should be investigated. Intact rocks are generally preferred due to relatively easy side of their homogeneous characteristics in numerical modelling phases. However, it is very hard to extract intact samples from vuggy rocks because of their complex pore sizes and distributions. In this study, the feasibility of concrete samples to model and mimic the failure behavior vuggy rocks was investigated. For this purpose, concrete samples were prepared at a mixture of %65 cement dust and %35 water and their physical and mechanical properties were determined by laboratory experiments. The obtained physical and mechanical properties were used to

  3. Comparison of mechanistic models in the initial rate enzymatic hydrolysis of AFEX-treated wheat straw

    Directory of Open Access Journals (Sweden)

    Agbogbo Frank K

    2010-03-01

    Full Text Available Abstract Background Different mechanistic models have been used in the literature to describe the enzymatic hydrolysis of pretreated biomass. Although these different models have been applied to different substrates, most of these mechanistic models fit into two- and three-parameter mechanistic models. The purpose of this study is to compare the models and determine the activation energy and the enthalpy of adsorption of Trichoderma reesei enzymes on ammonia fibre explosion (AFEX-treated wheat straw. Experimental enzymatic hydrolysis data from AFEX-treated wheat straw were modelled with two- and three-parameter mechanistic models from the literature. In order to discriminate between the models, initial rate data at 49°C were subjected to statistical analysis (analysis of variance and scatter plots. Results For three-parameter models, the HCH-1 model best fitted the experimental data; for two-parameter models Michaelis-Menten (M-M best fitted the experimental data. All the three-parameter models fitted the data better than the two-parameter models. The best three models at 49°C (HCH-1, Huang and M-M were compared using initial rate data at three temperatures (35°, 42° and 49°C. The HCH-1 model provided the best fit based on the F values, the scatter plot and the residual sum of squares. Also, its kinetic parameters were linear in Arrhenius/van't Hoff's plots, unlike the other models. The activation energy (Ea is 47.6 kJ/mol and the enthalpy change of adsorption (ΔH is -118 kJ/mol for T. reesei enzymes on AFEX-treated wheat straw. Conclusion Among the two-parameter models, Michaelis-Menten model provided the best fit compared to models proposed by Humphrey and Wald. For the three-parameter models, HCH-1 provided the best fit because the model includes a fractional coverage parameter (ϕ which accounts for the number of reactive sites covered by the enzymes.

  4. A New Paradigm for Flare Particle Acceleration

    Science.gov (United States)

    Guidoni, Silvina E.; Karpen, Judith T.; DeVore, C. Richard

    2017-08-01

    The mechanism that accelerates particles to the energies required to produce the observed high-energy impulsive emission and its spectra in solar flares is not well understood. Here, we propose a first-principle-based model of particle acceleration that produces energy spectra that closely resemble those derived from hard X-ray observations. Our mechanism uses contracting magnetic islands formed during fast reconnection in solar flares to accelerate electrons, as first proposed by Drake et al. (2006) for kinetic-scale plasmoids. We apply these ideas to MHD-scale islands formed during fast reconnection in a simulated eruptive flare. A simple analytic model based on the particles’ adiabatic invariants is used to calculate the energy gain of particles orbiting field lines in our ultrahigh-resolution, 2.5D, MHD numerical simulation of a solar eruption (flare + coronal mass ejection). Then, we analytically model electrons visiting multiple contracting islands to account for the observed high-energy flare emission. Our acceleration mechanism inherently produces sporadic emission because island formation is intermittent. Moreover, a large number of particles could be accelerated in each macroscopic island, which may explain the inferred rates of energetic-electron production in flares. We conclude that island contraction in the flare current sheet is a promising candidate for electron acceleration in solar eruptions. This work was supported in part by the NASA LWS and H-SR programs..

  5. Diurnal Variation of Anterior Chamber Flare

    Directory of Open Access Journals (Sweden)

    Mehmet Adam

    2015-04-01

    Full Text Available Objectives: To investigate the ideal time and reproducibility of anterior chamber flare measurements. Materials and Methods: Anterior chamber flare measurements were performed with laser flaremetre device at 8 am to 45 volunteers and these measurements were repeated on the same day at 12 pm and 4 pm. Results: Twenty-five (55.5% of the volunteers were women and 20 (44.5% were men; mean age was 28.67±7.40 (18-49 years. The mean anterior chamber flare measurements taken following the ophthalmologic examination were 5.94±1.41 foton/msn at 8 am, 5.65±1.45 foton/msn at 12 pm, and 5.79±1.20 foton/msn at 4 pm. No statistical difference was found between the measurements (p=0.08. Subgroup analysis according to eye color, revealed no significant difference between flare measurements in brown, hazel, and green eyes (p=0.21. Correlation analysis demonstrated association between age and all flare measurements within the day (r=0.24, p=0.03; r=0.41, p=0.01, r=0.27, p=0.01. Conclusion: No significant diurnal change was detected in the flare measurements of our study subjects but positive correlation with age was observed. Hence, all flare measurements within a day are reliable and have high repeatability in healthy subjects. (Turk J Ophthalmol 2015; 45: 52-5

  6. Hypertension management initiative prospective cohort study: comparison between immediate and delayed intervention groups.

    Science.gov (United States)

    Tobe, S W; Moy Lum-Kwong, M; Von Sychowski, S; Kandukur, K; Kiss, A; Flintoft, V

    2014-01-01

    The Heart and Stroke Foundation of Ontario's Hypertension Management Initiative (HMI) was a pragmatic implementation of clinical practice guidelines for hypertension management in primary care clinics. The HMI was a prospective delayed phase cohort study of 11 sites enrolling patients in two blocks starting 9 months apart in 2007. The intervention was an evidence-informed chronic disease management program consisting of an interprofessional educational intervention with practice tools to implement the Canadian Hypertension Education Program's clinical practice guidelines. This study compares the change in blood pressure (BP) from baseline to 9 months after the intervention between groups. In the immediate intervention group, the mean BP at baseline was 134.6/79.1 mm Hg (18.2/11.5) and in the delayed intervention group 134.2/77.1 mm Hg (18.9/11.8). The fall in BP in the immediate intervention group from baseline to 9 months after the intervention was 7.3/3.6 mm Hg (95% confidence interval (CI): 5.9-8.7/2.6-4.5) and in the delayed group 8.1/3.3 mm Hg (95% CI: 7.0-9.3/2.5-4.1) (all Phypertension can rapidly lead to lower BP levels.

  7. Preparing beginning reading teachers: An experimental comparison of initial early literacy field experiences.

    Science.gov (United States)

    Al Otaiba, Stephanie; Lake, Vickie E; Greulich, Luana; Folsom, Jessica S; Guidry, Lisa

    2012-01-01

    This randomized-control trial examined the learning of preservice teachers taking an initial Early Literacy course in an early childhood education program and of the kindergarten or first grade students they tutored in their field experience. Preservice teachers were randomly assigned to one of two tutoring programs: Book Buddies and Tutor Assisted Intensive Learning Strategies (TAILS), which provided identical meaning-focused instruction (shared book reading), but differed in the presentation of code-focused skills. TAILS used explicit, scripted lessons, and the Book Buddies required that code-focused instruction take place during shared book reading. Our research goal was to understand which tutoring program would be most effective in improving knowledge about reading, lead to broad and deep language and preparedness of the novice preservice teachers, and yield the most successful student reading outcomes. Findings indicate that all pre-service teachers demonstrated similar gains in knowledge, but preservice teachers in the TAILS program demonstrated broader and deeper application of knowledge and higher self-ratings of preparedness to teach reading. Students in both conditions made similar comprehension gains, but students tutored with TAILS showed significantly stronger decoding gains.

  8. COMPARISON OF ANTIRETROVIRAL SCHEMES USED IN INITIAL THERAPY FOR TREATMENT OF HIV/AIDS

    Directory of Open Access Journals (Sweden)

    Luana LENZI

    2015-12-01

    Full Text Available A problem of highly active antiretroviral therapy (HAART in HIV patients is their adherence to treatment. The aim of this study was to compare the schemes adopted in the initial therapy of these treatments with their adherence, changes in HAART schemes and treatment costs. The study included patients over 16 years old, HIV positive, in treatment for more than 30 days. Adherence to HAART was calculated based on the withdrawal of the drug, which was related to the total treatment time. We evaluated how many patients changed HAART. The costs of each regimen were also estimated and related to the benefit of each treatment. 142 patients who were between 38 and 1,150 days of treatment were included (57.7% women. The schemes with lower costs, highest adherence and greater benefit were efavirenz with biovir and efavirenz with lamivudine and tenofovir. This study suggested the advantageous therapeutic regimens to start of treatment, both from the point of view of patients and the health system. This information can serve as a subsidy to clinicians in the decision of starting HAART.

  9. Enhancing the sustainability and climate resiliency of health care facilities: a comparison of initiatives and toolkits.

    Science.gov (United States)

    Balbus, John; Berry, Peter; Brettle, Meagan; Jagnarine-Azan, Shalini; Soares, Agnes; Ugarte, Ciro; Varangu, Linda; Prats, Elena Villalobos

    2016-09-01

    Extreme weather events have revealed the vulnerability of health care facilities and the extent of devastation to the community when they fail. With climate change anticipated to increase extreme weather and its impacts worldwide-severe droughts, floods, heat waves, and related vector-borne diseases-health care officials need to understand and address the vulnerabilities of their health care systems and take action to improve resiliency in ways that also meet sustainability goals. Generally, the health sector is among a country's largest consumers of energy and a significant source of greenhouse gas emissions. Now it has the opportunity lead climate mitigation, while reducing energy, water, and other costs. This Special Report summarizes several initiatives and compares three toolkits for implementing sustainability and resiliency measures for health care facilities: the Canadian Health Care Facility Climate Change Resiliency Toolkit, the U.S. Sustainable and Climate Resilient Health Care Facilities Toolkit, and the PAHO SMART Hospitals Toolkit of the World Health Organization/Pan American Health Organization. These tools and the lessons learned can provide a critical starting point for any health system in the Americas.

  10. Radiative Hydrodynamic Models of Optical and Ultraviolet Emission from M Dwarf Flares

    CERN Document Server

    Allred, J C; Carlsson, M; Hawley, S L; Abbett, William P.; Allred, Joel C.; Carlsson, Mats; Hawley, Suzanne L.

    2006-01-01

    We report on radiative hydrodynamic simulations of M dwarf stellar flares and compare the model predictions to observations of several flares. The flares were simulated by calculating the hydrodynamic response of a model M dwarf atmosphere to a beam of non-thermal electrons. Radiative backwarming through numerous soft X-ray, extreme ultraviolet, and ultraviolet transitions are also included. The equations of radiative transfer and statistical equilibrium are treated in non-LTE for many transitions of hydrogen, helium and the Ca II ion allowing the calculation of detailed line profiles and continuum radiation. Two simulations were carried out, with electron beam fluxes corresponding to moderate and strong beam heating. In both cases we find the dynamics can be naturally divided into two phases: an initial gentle phase in which hydrogen and helium radiate away much of the beam energy, and an explosive phase characterized by large hydrodynamic waves. During the initial phase, lower chromospheric material is evap...

  11. The evolution of high-temperature plasma in magnetar magnetospheres and its implications for giant flares

    Energy Technology Data Exchange (ETDEWEB)

    Takamoto, Makoto [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, Heidelberg D69117 (Germany); Kisaka, Shota [Institute of Particle and Nuclear Studies, KEK, 1-1, Oho, Tsukuba 305-0801 (Japan); Suzuki, Takeru K. [Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan); Terasawa, Toshio, E-mail: makoto.takamoto@mpi-hd.mpg.de, E-mail: kisaka@post.kek.jp, E-mail: stakeru@nagoya-u.jp, E-mail: terasawa@icrr.u-tokyo.ac.jp [Institute for Cosmic Ray Research, University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa city, Chiba 277-8582 (Japan)

    2014-05-20

    In this paper we propose a new mechanism describing the initial spike of giant flares in the framework of the starquake model. We investigate the evolution of a plasma on a closed magnetic flux tube in the magnetosphere of a magnetar in the case of a sudden energy release, and discuss the relationship with observations of giant flares. We perform one-dimensional, numerical simulations of the relativistic magnetohydrodynamics in Schwarzschild geometry. We assume energy is injected at the footpoints of the loop by a hot star surface containing random perturbations of the transverse velocity. Alfvén waves are generated and propagate upward, accompanying very hot plasma which is also continuously heated by nonlinearly generated compressive waves. We find that the front edges of the fireball regions collide at the top of the tube with their symmetrically launched counterparts. This collision results in an energy release that can describe the light curve of the initial spikes of giant flares.

  12. The Variable Crab Nebula: Evidence for a Connection between GeV flares and Hard X-ray Variations

    Science.gov (United States)

    Wilson-Hodge, Colleen A.; Kust Harding, Alice; Hays, Elizabeth A.; Cherry, Michael L.; Case, Gary L.; Finger, Mark H.; Jenke, Peter; Zhang, Xiao-Ling

    2016-04-01

    In 2010, hard X-ray variations (Wilson-Hodge et al. 2011) and GeV flares (Tavani et al 2011, Abdo et al. 2011) from the Crab Nebula were discovered. Connections between these two phenomena were unclear, in part because the timescales were quite different, with yearly variations in hard X-rays and hourly to daily variations in the GeV flares. The hard X-ray flux from the Crab Nebula has again declined since 2014, much like it did in 2008-2010. During both hard X-ray decline periods, the Fermi LAT detected no GeV flares, suggesting that injection of particles from the GeV flares produces the much slower and weaker hard X-ray variations. The timescale for the particles emitting the GeV flares to lose enough energy to emit synchrotron photons in hard X-rays is consistent with the yearly variations observed in hard X-rays and with the expectation that the timescale for variations slowly increases with decreasing energy. This hypothesis also predicts even slower and weaker variations below 10 keV, consistent with the non-detection of counterparts to the GeV flares by Chandra (Weisskopf et al 2013). We will present a comparison of the observed hard X-ray variations and a simple model of the decay of particles from the GeV flares to test our hypothesis.

  13. Advances In Understanding Solar And Stellar Flares

    Science.gov (United States)

    Kowalski, Adam F.

    2016-07-01

    Flares result from the sudden reconnection and relaxation of magnetic fields in the coronae of stellar atmospheres. The highly dynamic atmospheric response produces radiation across the electromagnetic spectrum, from the radio to X-rays, on a range of timescales, from seconds to days. New high resolution data of solar flares have revealed the intrinsic spatial properties of the flaring chromosphere, which is thought to be where the majority of the flare energy is released as radiation in the optical and near-UV continua and emission lines. New data of stellar flares have revealed the detailed properties of the broadband (white-light) continuum emission, which provides straightforward constraints for models of the transformation of stored magnetic energy in the corona into thermal energy of the lower atmosphere. In this talk, we discuss the physical processes that produce several important spectral phenomena in the near-ultraviolet and optical as revealed from new radiative-hydrodynamic models of flares on the Sun and low mass stars. We present recent progress with high-flux nonthermal electron beams in reproducing the observed optical continuum color temperature of T 10,000 K and the Balmer jump properties in the near-ultraviolet. These beams produce dense, heated chromospheric condensations, which can explain the shape and strength of the continuum emission in M dwarf flares and the red-wing asymmetries in the chromospheric emission lines in recent observations of solar flares from the Interface Region Imaging Spectrograph. Current theoretical challenges and future modeling directions will be discussed, as well as observational synergies between solar and stellar flares.

  14. Initial Comparison of Direct and Legacy Modeling Approaches for Radial Core Expansion Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shemon, Emily R. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-10-10

    not conservative and could be overestimating reactivity feedback effects that are closely tied to reactor safety. We conclude that there is indeed value in performing direct simulation of deformed meshes despite the increased computational expense. PROTEUS-SN is already part of the SHARP multi-physics toolkit where both thermal hydraulics and structural mechanical feedback modeling can be applied but this is the first comparison of direct simulation to legacy techniques for radial core expansion.

  15. Health workforce responses to global health initiatives funding: a comparison of Malawi and Zambia

    Directory of Open Access Journals (Sweden)

    Brugha Ruairí

    2010-08-01

    Full Text Available Abstract Background Shortages of health workers are obstacles to utilising global health initiative (GHI funds effectively in Africa. This paper reports and analyses two countries' health workforce responses during a period of large increases in GHI funds. Methods Health facility record reviews were conducted in 52 facilities in Malawi and 39 facilities in Zambia in 2006/07 and 2008; quarterly totals from the last quarter of 2005 to the first quarter of 2008 inclusive in Malawi; and annual totals for 2004 to 2007 inclusive in Zambia. Topic-guided interviews were conducted with facility and district managers in both countries, and with health workers in Malawi. Results Facility data confirm significant scale-up in HIV/AIDS service delivery in both countries. In Malawi, this was supported by a large increase in lower trained cadres and only a modest increase in clinical staff numbers. Routine outpatient workload fell in urban facilities, in rural health centres and in facilities not providing antiretroviral treatment (ART, while it increased at district hospitals and in facilities providing ART. In Zambia, total staff and clinical staff numbers stagnated between 2004 and 2007. In rural areas, outpatient workload, which was higher than at urban facilities, increased further. Key informants described the effects of increased workloads in both countries and attributed staff migration from public health facilities to non-government facilities in Zambia to PEPFAR. Conclusions Malawi, which received large levels of GHI funding from only the Global Fund, managed to increase facility staff across all levels of the health system: urban, district and rural health facilities, supported by task-shifting to lower trained staff. The more complex GHI arena in Zambia, where both Global Fund and PEPFAR provided large levels of support, may have undermined a coordinated national workforce response to addressing health worker shortages, leading to a less effective

  16. Balloon-augmented Onyx endovascular ligation: initial human experience and comparison with coil ligation.

    Science.gov (United States)

    Osanai, Toshiya; Bain, Mark D; Toth, Gabor; Hussain, M Shazam; Hui, Ferdinand K

    2015-08-01

    Carotid artery sacrifice remains an important procedure for cerebral vascular disorders despite the development of new endovascular devices. Conventional carotid artery sacrifice with detachable coils alone often requires numerous coils to complete occlusion. To describe the initial human experience with balloon-augmented Onyx and coil vessel sacrifice based on our previous experience with animals. We performed a retrospective review of patients who underwent carotid artery sacrifice between 2008 and 2012 in accordance with local investigational review board approval. Two methods were used to occlude carotid arteries-namely, combined Onyx and coil embolization and traditional coil embolization. We compared the two methods for the cost of embolizate, time to occlude the vessels, and the number of coils. Eight consecutive patients (combined group n=3, traditional group n=5) were assessed. The median cost of embolic material was $6321 in the combined Onyx and coil embolization group and $29 996 in the traditional coil embolization group. The median time from first coil placement to achievement of vessel occlusion was 52 min in the Onyx group and 113 min in the coil embolization group. The median number of coils used was 4 in the Onyx group and 35 in the coil embolization group (p<0.05). No symptomatic complications or recurrences were seen in the combined group. Balloon-augmented Onyx endovascular ligation may reduce costs and fluoroscopy times during vessel sacrifice. Further studies in a larger number of patients are needed to confirm these findings. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  17. Pneumatic versus laser ureteroscopic lithotripsy: a comparison of initial outcomes and cost.

    Science.gov (United States)

    Demir, Aslan; Karadağ, Mert Ali; Ceçen, Kurşat; Uslu, Mehmet; Arslan, Omer Erkam

    2014-11-01

    To audit the cost of laser versus pneumatic semirigid ureteroscopic lithotripsy and to analyze their relative initial outcomes and cost. Hundred and eighty-seven patients who underwent semirigid ureteroscopic lithotripsy were analyzed retrospectively in terms of age and sex of the patients; location and size of the stones; the type of probe and ancillary equipment such as guide wire, basket catheter, JJ stent requirements; irrigation amount; operation time; the cost of the anesthesia and further treatments such as a JJ stent removal operation and shock wave lithotripsy requirements and their costs. Two groups were formed based on this type of lithotripters, pneumatic and laser lithotripsy. Operation times (min.) in terms of the stone size, for stones 100 mm(2) were 20.75 ± 10.78 and 25.82 ± 14.23, respectively (p = 0.007). Operation times for the pneumatic and laser groups were 33.05 ± 11.36 and 15.25 ± 6.14, respectively (p pneumatic and laser groups were 89.6 % (n = 69) and 98.2 % (n = 108), respectively (p = 0.01). The mean cost of the operations for each of the study groups was 261.5 ± 66.13 and 311.7 ± 51.97 US$, respectively (p = 0.001). The mean cost in terms of the stone size, for stones 100 mm(2), was 272.86 ± 53.05 and 323.71 ± 66.88 US$, respectively (p = 0.01). It seems that usage of laser lithotripsy (LL) in patients with ureteral stones is more effective than pneumatic lithotripsy (PL) in terms of operation time and SF rate. On the other hand, the mean cost of LL seems to be more expensive than PL. Urologists should think these parameters before the choice of these two treatment modalities. The higher the effectiveness, the greater the cost.

  18. Comparison of initial loading doses of 5 mg and 10 mg for warfarin therapy

    Directory of Open Access Journals (Sweden)

    Sidnei Lastória

    2014-03-01

    Full Text Available CONTEXT: The question of what is the best loading dosage of warfarin when starting anticoagulant treatment has been under discussion for ten years. We were unable to find any comparative studies of these characteristics conducted here in Brazil. OBJECTIVE: To compare the safety and efficacy of two initial warfarin dosage regimens for anticoagulant treatment. METHODS: One-hundred and ten consecutive patients of both sexes, with indications for anticoagulation because of venous or arterial thromboembolism, were analyzed prospectively. During the first 3 days of treatment, these patients were given adequate heparin to keep aPTT (activated partial thromboplastin time between 1.5 and 2.5, plus 5 mg of warfarin. From the fourth day onwards, their warfarin doses were adjusted using International Normalized Ratios (INR; target range: 2 to 3. This prospective cohort was compared with a historical series of 110 patients had been given 10 mg of warfarin on the first 2 days and 5 mg on the third day with adjustments based on INR thereafter. Outcomes analyzed were as follows: recurrence of thromboembolism, bleeding events and time taken to enter the therapeutic range. RESULTS: Efficacy, safety and length of hospital stay were similar in both samples. The sample that were given 10 mg entered the therapeutic range earlier (means: 4.5 days vs. 5.8 days, were on lower doses at discharge and had better therapeutic indicators at the first return appointment. CONCLUSIONS: The 10 mg dosage regimen took less time to attain the therapeutic range and was associated with lower warfarin doses at discharge and better INR at first out-patients follow-up visit.

  19. Photoelectron spectrum in the upper atmosphere of the earth during solar flares

    Energy Technology Data Exchange (ETDEWEB)

    Avakyan, S.V.; Kudryashev, G.S.

    1985-05-01

    This paper presents calculations of the photoelectron spectrum during solar flares. A comparison with the data of satellite measurements is presented. Verification of the calculated model of the experimental data has been carried out, showing satisfactory agreement between the results of the calculations and the variations of the photoelectron intensities and emission of the upper atmosphere. The model is suitable for the evaluation of the degree of disturbance of ionospheric parameters during flares, particularly above 100 km, where the role of photoelectrons increases greatly.

  20. A weak thermal response on a strong electron acceleration in a ‘cold’ flare

    Science.gov (United States)

    Fleishman, Gregory D.; Motorina, Galina; Nita, Gelu M.; Kontar, Eduard

    2017-08-01

    Solar flares are sudden explosive processes in the solar atmosphere, which demonstrate remarkable variety of the partitions between various energy components. Understanding the flare acceleration site requires knowledge of exactly how flare energization works and what is the partition between nonthermal, thermal and kinetic energies. These partitions are known to vary broadly resulting in both ‘entirely thermal’ and primarily nonthermal, so-called ‘cold’ flares. These ‘cold flares’ are characterized by domination of nonthermal component, but very weak thermal emission and almost no soft X-ray enhancement; thus GOES often does not recognize such events as flares. Here we attempt to quantify the thermal and nonthermal energies and their evolving relationship in a 2013-Nov-05 cold flare. For nonthermal diagnostics we use the RHESSI data, while the AIA data are employed for the thermal diagnostics. We applied RHESSI spectral fits, with both ‘cold’ and ‘warm’ target to bracketing the low-energy cutoff, to quantify the rate of the nonthermal energy deposition in this flare as well to characterize a (tiny) hot component. We then computed evolving differential emission measure maps using the regularized inversion method and derived from them the emission measure and temperature maps. These inputs allowed us to accurately calculate the evolving thermal energy in the flare. This thermal energy was compared with the mentioned above rate of the nonthermal energy deposition. This comparison suggests that the observed plasma heating is entirely supplied by the loss of the nonthermal energy released in the impulsive phase of the flare. Using vector magnetic data from SDO/HMI we created a nonlinear force-free field reconstruction of the region of interest, and, using the available X-ray and EUV data set as a constraint, we developed a 3D model of the flare capable of correctly reproducing the data set. To validate the model, we used microwave data from Nobeyama

  1. Flaring down project for Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Bienek, S. [Joh. Heinr. Bornemann GmbH, Obernkirchen (Germany)

    2008-06-15

    Multiphase boosting as a production scenario for lowering wellhead backpressure, avoiding field separation stations, and achieving longer flow distances is widely accepted by major oil companies. Flaring down of gas is no longer necessary and therefore the use of multiphase pumps has a positive impact on a healthy environment. The twin-screw pump plays a major role when selecting the equipment. Due to its volumetric character heavy slugging, varying water content and other typical multiphase operating challenges, this pump type is well suited for this purpose. With its low speed the fluid is treated very sensitively, so as to widely avoid emulsifying oil and water - a definite advantage for the later separation of the phases. (orig.)

  2. Solar flare count periodicities in different X-ray flare classes

    Science.gov (United States)

    Gao, Peng-Xin; Xu, Jing-Chen

    2016-04-01

    Using the Morlet wavelet transform and the Hilbert-Huang transform (HHT), we investigate the periodic behaviours of C, M and X-class flare counts, respectively, recorded by the Geostationary Operational Environmental Satellites (GOES) from 1983 May to 2014 December, which cover the two complete solar cycles (SCs) 22 and 23 as well as the part of declining phase of SC 21 and rise and maximum phases of SC 24. Analyses show that the periodic behaviours of various class flare counts are different. (1) Not all periods of various class flare counts appear dominant during the cycle maxima. For C-class flares, during SC 23, periods appear dominant during the maximum phase, however, compared to those during SC 23, there are more periods during the declining phase of SC 22; for M-class flares, during SCs 22 and 23, periods appear dominant during the cycle maxima; for X-class flares, during SC 22, almost all periods appear during the maximum phase; however, during SC 23, there are more periods during the declining phase compared to those during SC 22. (2) For C-class flares, the appearance of periods do not follow the amplitude of C-class flare cycles; while, for M and X-class flares, the appearance of periods follows the amplitude of the investigated corresponding class flare cycles. (3) From the overall trends, the 10 yr and longer time-scale trends of the monthly numbers of M and X-class flares, we can infer that the maximum values of the monthly M and X-class flare numbers would increase during SC 25.

  3. Determination of solar flare accelerated ion angular distributions from SMM gamma ray and neutron measurements and determination of the He-3/H ratio in the solar photosphere from SMM gamma ray measurements

    Science.gov (United States)

    Lingenfelter, Richard E.

    1989-01-01

    Comparisons of Solar Maximum Mission (SMM) observations of gamma-ray line and neutron emission with theoretical calculation of their expected production by flare accelerated ion interactions in the solar atmosphere have led to significant advances in the understanding of solar flare particle acceleration and interaction, as well as the flare process itself. These comparisons have enabled the determination of, not only the total number and energy spectrum of accelerated ions trapped at the sun, but also the ion angular distribution as they interact in the solar atmosphere. The Monte Carlo program was modified to include in the calculations of ion trajectories the effects of both mirroring in converging magnetic fields and of pitch angle scattering. Comparing the results of these calculations with the SMM observations, not only the angular distribution of the interacting ions can be determined, but also the initial angular distribution of the ions at acceleration. The reliable determination of the solar photospheric He-3 abundance is of great importance for understanding nucleosynthesis in the early universe and its implications for cosmology, as well as for the study of the evolution of the sun. It is also essential for the determinations of the spectrum and total number of flare accelerated ions from the SMM/GRS gamma-ray line measurements. Systematic Monte Carlo calculations of the time dependence were made as a function of the He-3 abundance and other variables. A new series of calculations were compared for the time-dependent flux of 2.223 MeV neutron capture line emission and the ratio of the time-integrated flux in the 2.223 MeV line to that in the 4.1 to 6.4 MeV nuclear deexcitation band.

  4. Solar Flare Prediction Using SDO/HMI Vector Magnetic Field Data with a Machine-Learning Algorithm

    Science.gov (United States)

    Bobra, M.; Couvidat, S. P.

    2014-12-01

    We attempt to forecast M-and X-class solar flares using a machine-learning algorithm, called Support Vector Machine (SVM), and four years of data from the Solar Dynamics Observatory's Helioseismic and Magnetic Imager, the first instrument to continuously map the full-disk photospheric vector magnetic field from space (Schou et al., 2012). Most flare forecasting efforts described in the literature use either line-of-sight magnetograms or a relatively small number of ground-based vector magnetograms. This is the first time such a large dataset of vector magnetograms has been used to forecast solar flares. We build a catalog of flaring and non-flaring active regions sampled from a database of 2,071 active regions, comprised of 1.5 million active region patches of vector magnetic field data, and characterize each active region by 25 parameters --- which include the flux, energy, shear, current, helicity, gradient, geometry, and Lorentz force. We then train and test the machine-learning algorithm. Finally, we estimate the performance of this algorithm using forecast verification metrics with an emphasis on the true skill statistic (TSS). Bloomfield et al. (2012) suggest the use of the TSS as it is not sensitive to the class imbalance problem. Indeed, there are many more non-flaring active regions in a given time interval than flaring ones: this class imbalance distorts many performance metrics and renders comparison between various studies somewhat unreliable. We obtain relatively high TSS scores and overall predictive abilities. We surmise that this is partly due to fine-tuning the SVM for this purpose and also to an advantageous set of features that can only be calculated from vector magnetic field data. We also apply a feature selection algorithm to determine which of our 25 features are useful for discriminating between flaring and non-flaring active regions and conclude that only a handful are needed for good predictive abilities.

  5. Neutron decay electrons after the solar flare of 1980 June 21

    Science.gov (United States)

    Ruffolo, D.; Dröge, W.; Klecker, B.

    1996-06-01

    We have found evidence for fluxes of energetic electrons in interplanetary space on board the ISEE-3/ICE spacecraft which we interpret as the decay products of neutrons generated in a solar flare on 1980 June 21. The decay electrons arrived at the spacecraft shortly before the electrons from the flare and can be distinguished from the latter by their distinctive energy spectrum. The time profile of the decay electrons is in good agreement with the results from a simulation based on a scattering mean free path derived from a fit to the flare electron data. The comparison with simultaneously observed decay protons and a published direct measurement of high-energy neutrons places important constraints on the parent neutron spectrum.

  6. Solar-flare-induced Forbush decreases - Dependence on shock wave geometry

    Science.gov (United States)

    Thomas, B. T.; Gall, R.

    1984-01-01

    It is argued that the principal mechanism for the association of Forbush decreases with the passage of a solar flare shock wave is prolonged containment of cosmic ray particles behind the flare compression region, which acts as a semipermeable obstacle to particle motion along the field lines, leading to additional adiabatic cooling of the particles. Liouville's theorem is used to calculate the instantaneous distribution function at 1 AU for each particle arriving at the earth. By averaging over a large number of individual estimates, a representative estimate of the omnidirectional phase space density and the corresponding particle intensity is obtained. The energy change of individual particles at the shocks is found to be small in comparison to the energy lost by adiabatic cooling of the cosmic rays between the shock wave and the sun. The effects of particle rigidity, diffusion coefficient, and flare longitude on the magnitude of the Forbush decrease are quantitatively investigated.

  7. New solar flare evidence may solve mystery

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    An international group of scientists led by the Mullard Space Science Laboratory (MSSL), University College London, has discovered important new evidence that points to the cataclysmic events that trigger a solar flare and the mechanisms that drive its subsequent evolution.

  8. Active Longitude and Solar Flare Occurrences

    CERN Document Server

    Gyenge, N; Baranyi, T

    2015-01-01

    The aim of the present work is to specify the spatio-temporal characteristics of flare activity observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Geostationary Operational Environmental Satellite (GOES) satellites in connection with the behaviour of the longitudinal domain of enhanced sunspot activity known as active longitude (AL). By using our method developed for this purpose, we identified the AL in every Carrington Rotation provided by the Debrecen Photoheliographic Data (DPD). The spatial probability of flare occurrence has been estimated depending on the longitudinal distance from AL in the northern and southern hemispheres separately. We have found that more than the 60\\% of the RHESSI and GOES flares is located within $\\pm 36^{\\circ}$ from the active longitude. Hence, the most flare-productive active regions tend to be located in or close to the active longitudinal belt. This observed feature may allow predicting the geo-effective position of the domain of enhanced fla...

  9. Solar Flare Magnetic Fields and Plasmas

    CERN Document Server

    Fisher, George

    2012-01-01

    This volume is devoted to the dynamics and diagnostics of solar magnetic fields and plasmas in the Sun’s atmosphere. Five broad areas of current research in Solar Physics are presented: (1) New techniques for incorporating radiation transfer effects into three-dimensional magnetohydrodynamic models of the solar interior and atmosphere, (2) The connection between observed radiation processes occurring during flares and the underlying flare energy release and transport mechanisms, (3) The global balance of forces and momenta that occur during flares, (4) The data-analysis and theoretical tools needed to understand and assimilate vector magnetogram observations and (5) Connecting flare and CME phenomena to the topological properties of the magnetic field in the Solar Atmosphere. The role of the Sun’s magnetic field is a major emphasis of this book, which was inspired by a workshop honoring Richard C. (Dick) Canfield.  Dick has been making profound contributions to these areas of research over a long and pro...

  10. A UNIFIED MODEL FOR SOLAR FLARES

    Institute of Scientific and Technical Information of China (English)

    ChenPengfei; FangCheng; DingMingde; TangYuhua

    1999-01-01

    We performed 2.5 - dimensional numerical simulation for two cases, one with the the reconnection point at a high altitude, the other with the reconnection point at a low altitude, in the high-altitude case, the bright loop appears to rise for a long time, with its two footpoints separating and the field lines below the bright loop shrinking,which are all typical features of two - ribbon flares. In the low- altitude case, the bright loops cease rising only a short time after the impulsive phase of the reconnection and then become rather stable, which shows a large similarity to the compact flares. The results imply that the two types of solar flares, i. e., the two - ribbon flares and the compact ones, might be unified into the same magnetic reconnection model, where the height of the reconnection point leads to the bifurcation.

  11. X-ray Emission from Solar Flares

    Indian Academy of Sciences (India)

    Rajmal Jain; Malini Aggarwal; Raghunandan Sharma

    2008-03-01

    Solar X-ray Spectrometer (SOXS), the first space-borne solar astronomy experiment of India was designed to improve our current understanding of X-ray emission from the Sun in general and solar flares in particular. SOXS mission is composed of two solid state detectors, viz., Si and CZT semiconductors capable of observing the full disk Sun in X-ray energy range of 4–56 keV. The X-ray spectra of solar flares obtained by the Si detector in the 4–25 keV range show evidence of Fe and Fe/Ni line emission and multi-thermal plasma. The evolution of the break energy point that separates the thermal and non-thermal processes reveals increase with increasing flare plasma temperature. Small scale flare activities observed by both the detectors are found to be suitable to heat the active region corona; however their location appears to be in the transition region.

  12. Magnetic Fields in Limb Solar Flares

    Science.gov (United States)

    Lozitsky, V. G.; Lozitska, N. I.; Botygina, O. A.

    2013-02-01

    Two limb solar flares, of 14 July 2005 and 19 July 2012, of importance X1.2 and M7.7, are analyzed at present work. Magnetic field strength in named flares are investigated by Stokes I±V profiles of Hα and D3 HeI lines. There are direct evidences to the magnetic field inhomogeneity in flares, in particular, non-paralelism of bisectors in I+V and I-V profiles. In some flare places, the local maximums of bisectors splitting were found in both lines. If these bisector splittings are interpreted as Zeeman effect manifestation, the following magnetic field strengths reach up to 2200 G in Hα and 1300 G in D3. According to calculations, the observed peculiarities of line profiles may indicate the existence of optically thick emissive small-scale elements with strong magnetic fields and lowered temperature.

  13. 40 CFR 65.147 - Flares.

    Science.gov (United States)

    2010-07-01

    ... submission of the notice specified in § 65.167(a). Upon implementing the change, a flare compliance... standard cubic meter; where the net enthalpy per mole of offgas is based on combustion at 25 °C and 760...

  14. Solar Eruptions: Coronal Mass Ejections and Flares

    Science.gov (United States)

    Gopalswamy, Nat

    2012-01-01

    This lecture introduces the topic of Coronal mass ejections (CMEs) and solar flares, collectively known as solar eruptions. During solar eruptions, the released energy flows out from the Sun in the form of magnetized plasma and electromagnetic radiation. The electromagnetic radiation suddenly increases the ionization content of the ionosphere, thus impacting communication and navigation systems. Flares can be eruptive or confined. Eruptive flares accompany CMEs, while confined flares hav only electromagnetic signature. CMEs can drive MHD shocks that accelerate charged particles to very high energies in the interplanetary space, which pose radiation hazard to astronauts and space systems. CMEs heading in the direction of Earth arrive in about two days and impact Earth's magnetosphere, producing geomagnetic storms. The magnetic storms result in a number of effects including induced currnts that can disrupt power grids, railroads, and underground pipelines

  15. Exceptions to the rule: the X-flares of AR 2192 Lacking Coronal Mass Ejections

    Science.gov (United States)

    Thalmann, J. K.; Su, Y.; Temmer, M.; Veronig, A. M.

    2016-04-01

    NOAA Active region (AR) 2192, that was present on the Sun in October 2014, was the largest region which occurred since November 1990 (see Figure 1). The huge size accompanied by a very high activity level, was quite unexpected as it appeared during the unusually weak solar cycle 24. Nevertheless, the AR turned out to be one of the most prolific flaring ARs of cycle 24. It produced in total 6 X, 29 M, 79 C flares during its disk passage from October 18-29, 2014 (see Figure 2). Surprisingly, all flares greater than GOES class M5 and X were confined, i.e. had no coronal mass ejections (CME) associated. All the flare events had some obvious similarity in morphology, as they were located in the core of the AR and revealed only minor separation motion away from the neutral line but a large initial separation of the conjugate flare ribbons. In the paper by Thalmann et al. (2015) we describe the series of flares and give details about the confined X1.6 flare event from October 22, 2014 as well as the single eruptive M4.0 flare event from October 24, 2014. The study of the X1.6 flare revealed a large initial separation of flare ribbons together with recurrent flare brightenings, which were related to two episodes of enhanced hard X-ray emission as derived from RHESSI observations. This suggests that magnetic field structures connected to specific regions were repeatedly involved in the process of reconnection and energy release. Opposite to the central location of the sequence of confined events within the AR, a single eruptive (M4.0) event occurred on the outskirt of the AR in the vicinity of open magnetic fields. Our investigations revealed a predominantly north-south oriented magnetic system of arcade fields overlying the AR that could have preserved the magnetic arcade to erupt, and consequently kept the energy release trapped in a localized volume of magnetic field high up in the corona (as supported by the absence of a lateral motion of the flare ribbons and the

  16. Modeling Gamma-Ray Burst X-Ray Flares Within the Internal Shock Model

    Science.gov (United States)

    Maxham, Amanda; Zhang, Bing

    2009-12-01

    X-ray afterglow light curves have been collected for over 400 Swift gamma-ray bursts (GRBs) with nearly half of them having X-ray flares superimposed on the regular afterglow decay. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge, and spread, producing prompt emission and X-ray flares. We pay special attention to the time history of central engine activity, internal shocks, and observed flares, but do not calculate the shock dynamics and radiation processes in detail. Using the empirical Ep -E iso (Amati) relation with an assumed Band function spectrum for each collision and an empirical flare temporal profile, we calculate the gamma-ray (Swift/BAT band) and X-ray (Swift/XRT band) lightcurves for arbitrary central engine activity and compare the model results with the observational data. We show that the observed X-ray flare phenomenology can be explained within the internal shock model. The number, width, and occurring time of flares are then used to diagnose the central engine activity, putting constraints on the energy, ejection time, width, and number of ejected shells. We find that the observed X-ray flare time history generally reflects the time history of the central engine, which reactivates multiple times after the prompt emission phase with progressively reduced energy. The same shell model predicts an external shock X-ray afterglow component, which has a shallow decay phase due to the initial pile-up of shells onto the blast wave. However, the predicted X-ray afterglow is too bright as compared with the observed flux level, unless epsilon e is

  17. Simulation of multiple supra--arcade downflows in solar flares

    CERN Document Server

    Cécere, M; Costa, A; Elaskar, S; Maglione, S

    2012-01-01

    In later papers we have shown that sunward, generally dark, plasma features originated above posteruption flare arcades are consistent with a scenario where plasma voids are generated by the bouncing and interfering of shocks and expansion waves upstream of an initial localized deposition of energy which is collimated in the magnetic field direction. In this paper we analyze the multiple production and interaction of supra--arcade downflows (SAD) and the structure of individual SADs that make them relatively stable features while moving. We compare our results with observations and with the scenarios proposed by other authors.

  18. A Correlation between Proton Events and Hα Flares and its Possible Interpretation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Comparing space proton event data obtained during 1970-1980 with their identified Hα flare signatures we discover a peculiar correlation between them,according to which weak and small Hα flares can also produce proton events, and we reveal a characteristic "triangle" distribution of Hα flares accompanying protonevents. In order to explain such feature of proton events, we accept the accelerationmechanism by DC electric field. To deduce the parallel electric field we use the elec-tric current helicity (or force-free parameter α) determined by the Huairou vectormagnetograph. A comparison of E‖ with E shows that the former is negligiblein flaring sites. We show that in the flaring current sheet ion-anisotropy is gener-ated, and it, in turn, gives rise to ion-anisotropic instability which competes withelectric acceleration to give one possibility: the acceleration by DC electric field orannihilation of the built-up energy. The competition of DC acceleration and ion-anisotropic instability annihilation in the current sheet gives a possible explanationfor the above-mentioned "triangle" character of the distribution.

  19. Solar Flare Element Abundances from the Solar Assembly for X-rays (SAX) on MESSENGER

    CERN Document Server

    Dennis, B R; Schwartz, R A; Tolbert, A K; Starr, R D; Nittler, L R

    2015-01-01

    X-ray spectra in the range $1.5-8.5$~keV have been analyzed for 526 large flares detected with the Solar Assembly for X-rays (SAX) on the Mercury {\\em MESSENGER} spacecraft between 2007 and 2013. For each flare, the temperature and emission measure of the emitting plasma were determined from the spectrum of the continuum. In addition, with the SAX energy resolution of 0.6 keV (FWHM) at 6~keV, the intensities of the clearly resolved Fe-line complex at 6.7~keV and the Ca-line complex at 3.9~keV were determined, along with those of unresolved line complexes from S, Si, and Ar at lower energies. Comparisons of these line intensities with theoretical spectra allow the abundances of these elements relative to hydrogen to be derived, with uncertainties due to instrument calibration and the unknown temperature distribution of the emitting plasma. While significant deviations are found for the abundances of Fe and Ca from flare to flare, the abundances averaged over all flares are found to be enhanced over photospheri...

  20. Modelling emissions from natural gas flaring

    OpenAIRE

    G. Ezaina Umukoro; O. Saheed Ismail

    2017-01-01

    The world today recognizes the significance of environmental sustainability to the development of nations. Hence, the role oil and gas industry plays in environmental degrading activities such as gas flaring is of global concern. This study presents material balance equations and predicts results for non-hydrocarbon emissions such as CO2, CO, NO, NO2, and SO2 etc. from flaring (combustion) of 12 natural gas samples representing composition of natural gas of global origin. Gaseous emission est...

  1. Modelling emissions from natural gas flaring

    Directory of Open Access Journals (Sweden)

    G. Ezaina Umukoro

    2017-04-01

    Full Text Available The world today recognizes the significance of environmental sustainability to the development of nations. Hence, the role oil and gas industry plays in environmental degrading activities such as gas flaring is of global concern. This study presents material balance equations and predicts results for non-hydrocarbon emissions such as CO2, CO, NO, NO2, and SO2 etc. from flaring (combustion of 12 natural gas samples representing composition of natural gas of global origin. Gaseous emission estimates and pattern were modelled by coding material balance equations for six reaction types and combustion conditions with a computer program. On the average, anticipated gaseous emissions from flaring natural gas with an average annual global flaring rate 126 bcm per year (between 2000 and 2011 in million metric tonnes (mmt are 560 mmt, 48 mmt, 91 mmt, 93 mmt and 50 mmt for CO2, CO, NO, NO2 and SO2 respectively. This model predicted gaseous emissions based on the possible individual combustion types and conditions anticipated in gas flaring operation. It will assist in the effort by environmental agencies and all concerned to track and measure the extent of environmental pollution caused by gas flaring operations in the oil and gas industry.

  2. Analysis of Chromospheric Evaporation in Solar Flares

    Science.gov (United States)

    Sadykov, Viacheslav M.; Kosovichev, Alexander G.

    2017-08-01

    Chromospheric evaporation is one of the key processes of solar flares. Properties of chromospheric evaporation are thought to be closely connected to the energy release rates and energy transport mechanisms. Previous investigations revealed that in addition to electron-beam heating the chromospheric evaporation can be driven by heat fluxes and, probably, by other mechanisms. In this work, we present a study of flare events simultaneously observed by IRIS, SDO and RHESSI, focusing on spatio-temporal characteristics of the flare dynamics and its relation to the magnetic field topology. Event selection is performed using the Interactive Multi-Instrument Database of Solar Flares (IMIDSF) recently developed by the Center for Computational Heliophysics (CCH) at NJIT. The selection of IRIS observations was restricted to the fast-scanning regimes (coarse-raster or sparse-raster modes with ≥ 4 slit positions, ≥ 6`` spatial coverage, and ≤ 60 sec loop time). We have chosen 14 events, and estimated the spatially-resolved intensities and Doppler shifts of the chromospheric (Mg II), transition region (C II) and hot coronal (Fe XXI) lines reflecting the dynamics of the chromospheric evaporation. The correlations among the derived line profile properties, flare morphology, magnetic topology and hard X-ray characteristics will be presented, and compared with the RADYN flare models and other scenarios of chromospheric evaporations.

  3. Multithread Hydrodynamic Modeling of a Solar Flare

    Science.gov (United States)

    Warren, Harry P.

    2006-01-01

    Past hydrodynamic simulations have been able to reproduce the high temperatures and densities characteristic of solar flares. These simulations, however, have not been able to account for the slow decay of the observed flare emission or the absence of blueshifts in high spectral resolution line profiles. Recent work has suggested that modeling a flare as a sequence of independently heated threads instead of as a single loop may resolve the discrepancies between the simulations and observations. In this paper, we present a method for computing multithread, time-dependent hydrodynamic simulations of solar flares and apply it to observations of the Masuda flare of 1992 January 13. We show that it is possible to reproduce the temporal evolution of high temperature thermal flare plasma observed with the instruments on the GOES and Yohkoh satellites. The results from these simulations suggest that the heating timescale for a individual thread is on the order of 200 s. Significantly shorter heating timescales (20 s) lead to very high temperatures and are inconsistent with the emission observed by Yohkoh.

  4. Using Two-Ribbon Flare Observations and MHD Simulations to Constrain Flare Properties

    Science.gov (United States)

    Kazachenko, Maria D.; Lynch, Benjamin J.; Welsch, Brian

    2016-05-01

    Flare ribbons are emission structures that are frequently observed during flares in transition-region and chromospheric radiation. These typically straddle a polarity inversion line (PIL) of the radial magnetic field at the photosphere, and move apart as the flare progresses. The ribbon flux - the amount of unsigned photospheric magnetic flux swept out by flare ribbons - is thought to be related to the amount coronal magnetic reconnection, and hence provides a key diagnostic tool for understanding the physical processes at work in flares and CMEs. Previous measurements of the magnetic flux swept out by flare ribbons required time-consuming co-alignment between magnetograph and intensity data from different instruments, explaining why those studies only analyzed, at most, a few events. The launch of the Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA), both aboard the Solar Dynamics Observatory (SDO), presented a rare opportunity to compile a much larger sample of flare-ribbon events than could readily be assembled before. We created a dataset of 363 events of both flare ribbon positions and fluxes, as a function of time, for all C9.-class and greater flares within 45 degrees of disk center observed by SDO from June 2010 till April 2015. For this purpose, we used vector magnetograms (2D magnetic field maps) from HMI and UV images from AIA. A critical problem with using unprocessed AIA data is the existence of spurious intensities in AIA data associated with strong flare emission, most notably "blooming" (spurious smearing of saturated signal into neighboring pixels, often in streaks). To overcome this difficulty, we have developed an algorithmic procedure that effectively excludes artifacts like blooming. We present our database and compare statistical properties of flare ribbons, e.g. evolutions of ribbon reconnection fluxes, reconnection flux rates and vertical currents with the properties from MHD simulations.

  5. Effects of flare definitions on the statistics of derived flare distributions

    Science.gov (United States)

    Ryan, D. F.; Dominique, M.; Seaton, D.; Stegen, K.; White, A.

    2016-08-01

    The statistical examination of solar flares is crucial to revealing their global characteristics and behaviour. Such examinations can tackle large-scale science questions or give context to detailed single-event studies. However, they are often performed using standard but basic flare detection algorithms relying on arbitrary thresholds. This arbitrariness may lead to important scientific conclusions being drawn from results caused by subjective choices in algorithms rather than the true nature of the Sun. In this paper, we explore the effect of the arbitrary thresholds used in the Geostationary Operational Environmental Satellite (GOES) event list and Large Yield RAdiometer (LYRA) Flare Finder algorithms. We find that there is a small but significant relationship between the power law exponent of the GOES flare peak flux frequency distribution and the flare start thresholds of the algorithms. We also find that the power law exponents of these distributions are not stable, but appear to steepen with increasing peak flux. This implies that the observed flare size distribution may not be a power law at all. We show that depending on the true value of the exponent of the flare size distribution, this deviation from a power law may be due to flares missed by the flare detection algorithms. However, it is not possible determine the true exponent from GOES/XRS observations. Additionally we find that the PROBA2/LYRA flare size distributions are artificially steep and clearly non-power law. We show that this is consistent with an insufficient degradation correction. This means that PROBA2/LYRA should not be used for flare statistics or energetics unless degradation is adequately accounted for. However, it can be used to study variations over shorter timescales and for space weather monitoring.

  6. Statistical and theoretical studies of flares from Sagittarius A*

    Science.gov (United States)

    Li, Ya-Ping; Yuan, Qiang; Wang, Q. Daniel; Chen, P. F.; Neilsen, Joseph; Fang, Taotao; Zhang, Shuo; Dexter, Jason

    2017-01-01

    Multi-wavelength flares have routinely been observed from the supermassive black hole, Sagittarius A* (Sgr A*), at our Galactic center. The nature of these flares remains largely unclear, despite many theoretical models. We study the statistical properties of the Sgr A* X-ray flares and find that they are consistent with the theoretical prediction of the self-organized criticality system with the spatial dimension S = 3. We suggest that the X-ray flares represent plasmoid ejections driven by magnetic reconnection (similar to solar flares) in the accretion flow onto the black hole. Motivated by the statistical results, we further develop a time-dependent magnetohydrodynamic (MHD) model for the multi-band flares from Sgr A* by analogy with models of solar flares/coronal mass ejections (CMEs). We calculate the X-ray, infrared flare light curves, and the spectra, and find that our model can explain the main features of the flares.

  7. Plastic damping of Alfv\\'en waves in magnetar flares and delayed afterglow emission

    CERN Document Server

    Li, Xinyu

    2015-01-01

    Magnetar flares generate Alfv\\'en waves bouncing in the closed magnetosphere with energy up to $\\sim 10^{46}$ erg. We show that on a 10-ms timescale the waves are transmitted into the star and form a compressed packet of high energy density. This packet strongly shears the stellar crust and initiates a plastic flow, heating the crust and melting it hundreds of meters below the surface. A fraction of the deposited plastic heat is eventually conducted to the stellar surface, contributing to the surface afterglow months to years after the flare. A large fraction of heat is lost to neutrino emission or conducted into the core of the neutron star.

  8. Decomposition of the X-ray waveform of soft gamma-ray repeaters during giant flares

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We have analyzed the observations of SGR 1806-20 and SGR 1900+14 during giant flares made with the Rossi X-ray Timing Explorer.We have studied the pulsating tail after the initial spike and decomposed the pulse waveform into separate components of sub-pulses.We found evidence for phase shifts of those sub-pulses.This is probably due to rapid geometrical changes in the magnetic field of the neutron star during giant flares.The phase shifts could be used to constrain the geometry of the magnetic field.

  9. Foreign Language Analysis and Recognition (FLARe) Initial Progress

    Science.gov (United States)

    2012-11-29

    24  7 Haystack Media Player Page Incorporating the JavaScript-Driven Windows...its corresponding noun or adjective. We denote this modified AP5 system as AP5ATBLite. Table 8 shows the mean Bilingual Evaluation Understudy (BLEU... media files in the same language as the topic detector, is very different from the types of input that the topic detection systems of Section 2.3 were

  10. Staircase baker's map generates flaring-type time series

    Directory of Open Access Journals (Sweden)

    G. Radons

    2000-01-01

    Full Text Available The baker’s map, invented by Eberhard Hopf in 1937, is an intuitively accesible, two-dimensional chaos-generating discrete dynamical system. This map, which describes the transformation of an idealized two-dimensional dough by stretching, cutting and piling, is non-dissipative. Nevertheless the “x” variable is identical with the dissipative, one-dimensional Bernoulli-shift-generating map. The generalization proposed here takes up ideas of Yaacov Sinai in a modified form. It has a staircase-like shape, with every next step half as high as the preceding one. Each pair of neighboring elements exchanges an equal volume (area during every iteration step in a scaled manner. Since the density of iterated points is constant, the thin tail (to the right, say is visited only exponentially rarely. This observation already explains the map's main qualitative behavior: The “x” variable shows “flares”. The time series of this variable is closely analogous to that of a flaring-type dissipative dynamical system – like those recently described in an abstract economic model. An initial point starting its journey in the tale (or “antenna”, if we tilt the map upwards by 90 degrees is predictably attracted by the broad left hand (bottom part, in order to only very rarely venture out again to the tip. Yet whenever it does so, it thereby creates, with the top of a flare, a new “far-from-equilibrium” initial condition, in this reversible system. The system therefore qualifies as a discrete analogue to a far-from-equilibrium multiparticle Hamiltonian system. The height of the flare hereby corresponds to the momentary height of the H function of a gas. An observable which is even more closely related to the momentary negative entropy was recently described. Dependent on the numerical accuracy chosen, “Poincaré cycles” of two different types (periodic and nonperiodic can be observed for the first time.

  11. Feasibility of flare gas reformation to practical energy in Farashband gas refinery: no gas flaring.

    Science.gov (United States)

    Rahimpour, Mohammad Reaza; Jokar, Seyyed Mohammad

    2012-03-30

    A suggested method for controlling the level of hazardous materials in the atmosphere is prevention of combustion in flare. In this work, three methods are proposed to recover flare gas instead of conventional gas-burning in flare at the Farashband gas refinery. These methods aim to minimize environmental and economical disadvantages of burning flare gas. The proposed methods are: (1) gas to liquid (GTL) production, (2) electricity generation with a gas turbine and, (3) compression and injection into the refinery pipelines. To find the most suitable method, the refinery units that send gas to the flare as well as the required equipment for the three aforementioned methods are simulated. These simulations determine the amount of flare gas, the number of GTL barrels, the power generated by the gas turbine and the required compression horsepower. The results of simulation show that 563 barrels/day of valuable GTL products is produced by the first method. The second method provides 25 MW electricity and the third method provides a compressed natural gas with 129 bar pressure for injection to the refinery pipelines. In addition, the economics of flare gas recovery methods are studied and compared. The results show that for the 4.176MMSCFD of gas flared from the Farashband gas refinery, the electricity production gives the highest rate of return (ROR), the lowest payback period, the highest annual profit and mild capital investment. Therefore, the electricity production is the superior method economically. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. TEMPORAL EVOLUTION OF MULTIPLE EVAPORATING RIBBON SOURCES IN A SOLAR FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Graham, D. R.; Cauzzi, G., E-mail: dgraham@arcetri.astro.it [INAF-Osservatorio Astrofisico di Arcetri, I-50125 Firenze (Italy)

    2015-07-10

    We present new results from the Interface Region Imaging Spectrograph (IRIS) showing the dynamic evolution of chromospheric evaporation and condensation in a flare ribbon, with the highest temporal and spatial resolution to date. IRIS observed the entire impulsive phase of the X-class flare SOL2014-09-10T17:45 using a 9.4 s cadence “sit-and-stare” mode. As the ribbon brightened successively at new positions along the slit, a unique impulsive phase evolution was observed for many tens of individual pixels in both coronal and chromospheric lines. Each activation of a new footpoint displays the same initial coronal upflows of up to ∼300 km s{sup −1} and chromospheric downflows up to 40 km s{sup −1}. Although the coronal flows can be delayed by over 1 minute with respect to those in the chromosphere, the temporal evolution of flows is strikingly similar between all pixels and consistent with predictions from hydrodynamic flare models. Given the large sample of independent footpoints, we conclude that each flaring pixel can be considered a prototypical, “elementary” flare kernel.

  13. FLARE-GENERATED TYPE II BURST WITHOUT ASSOCIATED CORONAL MASS EJECTION

    Energy Technology Data Exchange (ETDEWEB)

    Magdalenic, J.; Marque, C.; Zhukov, A. N. [Solar-Terrestrial Center of Excellence, SIDC, Royal Observatory of Belgium, Avenue Circulaire 3, B-1180 Brussels (Belgium); Vrsnak, B. [Hvar Observatory, Faculty of Geodesy, Kaciceva 26, HR-10000 Zagreb (Croatia); Veronig, A., E-mail: Jasmina.Magdalenic@oma.be [IGAM/Kanzelhoehe Observatory, Institut of Physics, Universitaet Graz, Universitaetsplatz 5, A-8010 Graz (Austria)

    2012-02-20

    We present a study of the solar coronal shock wave on 2005 November 14 associated with the GOES M3.9 flare that occurred close to the east limb (S06 Degree-Sign E60 Degree-Sign ). The shock signature, a type II radio burst, had an unusually high starting frequency of about 800 MHz, indicating that the shock was formed at a rather low height. The position of the radio source, the direction of the shock wave propagation, and the coronal electron density were estimated using Nancay Radioheliograph observations and the dynamic spectrum of the Green Bank Solar Radio Burst Spectrometer. The soft X-ray, H{alpha}, and Reuven Ramaty High Energy Solar Spectroscopic Imager observations show that the flare was compact, very impulsive, and of a rather high density and temperature, indicating a strong and impulsive increase of pressure in a small flare loop. The close association of the shock wave initiation with the impulsive energy release suggests that the impulsive increase of the pressure in the flare was the source of the shock wave. This is supported by the fact that, contrary to the majority of events studied previously, no coronal mass ejection was detected in association with the shock wave, although the corresponding flare occurred close to the limb.

  14. He I D3 Observation of the 1984 May 22 M6.3 Solar Flare

    CERN Document Server

    Liu, Chang; Deng, Na; Lee, Jeongwoo; Zhang, Jifeng; Choudhary, Debi Prasad; Wang, Haimin

    2013-01-01

    He I D3 line has a unique response to the flare impact on the low solar atmosphere and can be a powerful diagnostic tool for energy transport processes. Using images obtained from the recently digitized films of Big Bear Solar Observatory, we report D3 observation of the M6.3 flare on 1984 May 22, which occurred in an active region with a circular magnetic polarity inversion line (PIL). The impulsive phase of the flare starts with a main elongated source that darkens in D3, inside of which bright emission kernels appear at the time of the initial small peak in hard X-rays (HXRs). These flare cores subsequently evolve into a sharp emission strand lying within the dark halo simultaneously with the main peak in HXRs, reversing the overall source contrast from -5% to 5%. The radiated energy in D3 during the main peak is estimated to be about 10^30 ergs, which is comparable to that carried by nonthermal electrons above 20 keV. Afterwards the flare proceeds along the circular PIL in the counterclockwise direction t...

  15. Photospheric and Coronal Observations of Abrupt Magnetic Restructuring in Two Flaring Active Regions

    Science.gov (United States)

    Petrie, Gordon

    2016-05-01

    For two major X-class flares observed by the Solar Dynamics Observatory (SDO) and the Solar TErrestrial RElations Observatory Ahead (STEREO-A) spacecraft when they were close to quadrature, we compare major, abrupt changes in the photospheric magnetic vector field to changes in the observed coronal magnetic structure during the two flares. The Lorentz force changes in strong photospheric fields within active regions are estimated from time series of SDO Helioseismic and Magnetic Imager (HMI) vector magnetograms. These show that the major changes occurred in each case near the main neutral line of the region and in two neighboring twisted opposite-polarity sunspots. In each case the horizontal parallel field strengthened significantly near the neutral line while the azimuthal field in the sunspots decreased, suggesting that a flux rope joining the two sunspots collapsed across the neutral line with reduced magnetic pressure because of a reduced field twist component. At the same time, the coronal extreme ultraviolet (EUV) loop structure was observed by the Atmospheric Imaging Assembly (AIA) onboard SDO and the Extreme Ultraviolet Imager (EUVI) on STEREO-A to decrease significantly in height during each eruption, discontinuous changes signifying ejection of magnetized plasma, and outward-propagating continuous but abrupt changes consistent with loop contraction. An asymmetry in the observed EUV loop changes during one of the flares matches an asymmetry in the photospheric magnetic changes associated with that flare. The observations are discussed in terms of the well-known tether-cutting and breakout flare initiation models.

  16. Modeling of a High/Soft State Flare in Cygnus X-1

    Science.gov (United States)

    Finke, Justin; Boettcher, Markus

    2004-04-01

    We present first modeling results of the rapid spectral variability of flares in the X-ray binary Cygnus X-1 in the high/soft state. The coupled radiation transfer and electron heating/cooling problem was solved with a fully time-dependent 2-D Monte-Carlo/Fokker-Planck code. Starting with an initial soft state model consisting of an optically thick accretion disk sandwiched by a hot corona, we modeled a high energy flare through an impulsive energy release in that corona. This flare could be representative of a reconection event of magnetic field lines anchored in the disk. We found that such a scenerio provides a good fit to the rapid (millisecond timescales) spectral evolution recently observed in Cyg X-1.

  17. Fixed drug eruption presenting as erythema dyschromicum perstans: a flare without taking any medications.

    Science.gov (United States)

    Mizukawa, Y; Shiohara, T

    1998-01-01

    Fixed drug eruption (FDE) can present as multiple pigmented macules that flare at fixed sites even when the patient has taken no medications. Although this presentation is not characteristic of FDE, it must be borne in mind in order to make a correct diagnosis. We describe such a patient whose condition was initially diagnosed as erythema dyschromicum perstans (EDP). Immunohistochemically intraepidermal T cells were distributed between basal and suprabasal keratinocytes in the lesional skin, a finding suggestive of FDE. A flare occurred not only with exposure to theophylline but also without exposure. A flare has never recurred and pigmented macules faded gradually after avoiding theophylline. On the basis of these findings, we recommend that patients with an EDP-like presentation be examined completely for causes such as drugs before labeling the cutaneous lesions.

  18. Psoriasis vulgaris flare during efalizumab therapy does not preclude future use: a case series

    Directory of Open Access Journals (Sweden)

    Krueger James G

    2005-08-01

    Full Text Available Abstract Background Severe psoriasis vulgaris can be extremely difficult to treat in some patients, even with the newer biological therapies available today. Case presentations We present two patients with severe chronic plaque psoriasis who received numerous systemic anti-psoriatic therapies with varied results. Both responded well to initial treatment with efalizumab (anti-CD11a, but then experienced a flare of their disease after missing a dose. However, after disease stablization, both patients responded well to re-introduction of efalizumab, one patient requiring concurrent treatment with infliximab (anti-TNF-α. Conclusion These cases are presented to characterize this "flare" reaction, and to inform health care providers that efalizumab can still be administered after disease flare, and again may be a successful therapy.

  19. The spatial, spectral and polarization properties of solar flare X-ray sources

    CERN Document Server

    Jeffrey, Natasha L S

    2014-01-01

    X-rays are a valuable diagnostic tool for the study of high energy accelerated electrons. Bremsstrahlung X-rays produced by, and directly related to, high energy electrons accelerated during a flare, provide a powerful diagnostic tool for determining both the properties of the accelerated electron distribution, and of the flaring coronal and chromospheric plasmas. This thesis is specifically concerned with the study of spatial, spectral and polarization properties of solar flare X-ray sources via both modelling and X-ray observations using the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Firstly, a new model is presented, accounting for finite temperature, pitch angle scattering and initial pitch angle injection. This is developed to accurately infer the properties of the acceleration region from the observations of dense coronal X-ray sources. Moreover, examining how the spatial properties of dense coronal X-ray sources change in time, interesting trends in length, width, position, number density ...

  20. Effects of flare definitions on the statistics of derived flare distributions

    CERN Document Server

    Ryan, Daniel F; Seaton, Dan; Stegen, Koen; White, Arthur

    2016-01-01

    The statistical examination of solar flares is crucial to revealing their global characteristics and behaviour. Such examinations can tackle large-scale science questions or give context to detailed single-event studies. However, they are often performed using standard but basic flare detection algorithms relying on arbitrary thresholds. This arbitrariness may lead to important scientific conclusions being drawn from results caused by subjective choices in algorithms rather than the true nature of the Sun. In this paper, we explore the effect of the arbitrary thresholds used in the GOES (Geostationary Operational Environmental Satellite) event list and LYRA (Large Yield RAdiometer) Flare Finder algorithms. We find that there is a small but significant relationship between the power law exponent of the GOES flare peak flux frequency distribution and the flare start thresholds of the algorithms. We also find that the power law exponents of these distributions are not stable, but appear to steepen with increasin...

  1. Spectral Hardening and Geoeffectiveness of Solar Flares

    Science.gov (United States)

    Jain, R.; Kumar, S.; Dave, H.; Deshpande, M. R.

    We present the results of a few typical flares that observed by the first space borne solar astronomy experiment of India namely "Solar X-ray Spectrometer (SOXS)" mission, which has completed one year of its successful operation in geostationary orbit. The SOXS mission onboard GSAT-2 Indian spacecraft was launched successfully by GSLV-D2 rocket on 08 May 2003 to study the energy release and particle acceleration in solar flares. The SOXS is composed of two independent payloads viz. SOXS Low Energy Detector (SLD) payload, and SOXS High Energy Detector (SHD) payload. We restrict our presentation to SLD payload that designed, developed and fabricated by Physical Research Laboratory (PRL) in collaboration with Space Application Centre (SAC), Ahmedabad and ISRO Satellite Centre (ISAC), Bangalore of Indian Space Research Organization (ISRO). We briefly present the scientific objectives and instrumentation of the SLD payload. The SLD payload employs the state-of-art solid state detectors viz. Si PIN and CZT detectors, which reveal sub-keV spectral and 100ms temporal resolution characteristics that are necessary to study the spectral response of the flare components. The dynamic range of Si and CZT detectors is 4-25 and 4-56 keV respectively. The SLD has observed more than 140 flares of C and M class since its commissioning in the orbit. We present the X-ray emission characteristics of a few typical flares in view of their spectral hardening and geo-effectiveness. We extend our study of these flares to optical and radio waveband observations in order to improve the relationship of X-ray spectral hardening and geo-effectiveness. The flares with harder spectra and associated with small or large CME, and radio emission at frequencies above 10 GHz are found geo-effective.

  2. Variations in the initial mass function in early-type galaxies: A critical comparison between dynamical and spectroscopic results

    CERN Document Server

    Smith, Russell J

    2014-01-01

    I present a comparison between published dynamical (ATLAS3D) and spectroscopic (Conroy & van Dokkum) constraints on the stellar initial mass function (IMF) in early-type galaxies, using the 34 galaxies in common between the two works. Both studies infer an average IMF mass factor $\\alpha$ (the stellar mass relative to a Kroupa-IMF population of similar age and metallicity) greater than unity, i.e. both methods favour an IMF which is heavier than that of the Milky Way, on average over the sample. However, on a galaxy-by-galaxy basis, there is no correlation between $\\alpha$ inferred from the two approaches. I investigate how the two estimates of $\\alpha$ are correlated systematically with the galaxy velocity dispersion, $\\sigma$, and with the Mg/Fe abundance ratio. The spectroscopic method, based on the strengths of metal absorption lines, yields a correlation only with metal abundance ratios: at fixed Mg/Fe, there is no residual correlation with $\\sigma$. The dynamical method, applied to exactly the same ...

  3. Role of Ryanodine Receptor Subtypes in Initiation and Formation of Calcium Sparks in Arterial Smooth Muscle: Comparison with Striated Muscle

    Directory of Open Access Journals (Sweden)

    Maik Gollasch

    2009-01-01

    Full Text Available Calcium sparks represent local, rapid, and transient calcium release events from a cluster of ryanodine receptors (RyRs in the sarcoplasmic reticulum. In arterial smooth muscle cells (SMCs, calcium sparks activate calcium-dependent potassium channels causing decrease in the global intracellular [Ca2+] and oppose vasoconstriction. This is in contrast to cardiac and skeletal muscle, where spatial and temporal summation of calcium sparks leads to global increases in intracellular [Ca2+] and myocyte contraction. We summarize the present data on local RyR calcium signaling in arterial SMCs in comparison to striated muscle and muscle-specific differences in coupling between L-type calcium channels and RyRs. Accordingly, arterial SMC Cav1.2 L-type channels regulate intracellular calcium stores content, which in turn modulates calcium efflux though RyRs. Downregulation of RyR2 up to a certain degree is compensated by increased SR calcium content to normalize calcium sparks. This indirect coupling between Cav1.2 and RyR in arterial SMCs is opposite to striated muscle, where triggering of calcium sparks is controlled by rapid and direct cross-talk between Cav1.1/Cav1.2 L-type channels and RyRs. We discuss the role of RyR isoforms in initiation and formation of calcium sparks in SMCs and their possible molecular binding partners and regulators, which differ compared to striated muscle.

  4. Short-term predictions of solar flares.

    Science.gov (United States)

    Burov, V. A.

    1990-02-01

    A review of present-day theoretical investigations of the problem of the accumulation and release of energy in solar flares permits advancing the opinion that only individual flare events are described by a concrete model and that a single model alone does not describe the entire diversity of flares. Consideration of the observational data does not permit claiming the existence of a single universal mechanism known today of flare events. It appears possible to treat the problem of prediction in terms of the algebra of logic (Boolean logic) and to compare the truth table with the often-used contingency table. The introduction of a number of very general assumptions permits forming a general approach to the development of predictive schemes and selection of the individual elements of the models and informative criteria. Experimental results are given on the testing of some prediction procedures. The author's procedure of routine short-term prediction of flares on the basis of the methods of instruction on pattern recognition implemented in the form of a set of programs is outlined. The results of the application of this procedure in 1986 - 1988 are presented.

  5. Radio-flaring Ultracool Dwarf Population Synthesis

    Science.gov (United States)

    Route, Matthew

    2017-08-01

    Over a dozen ultracool dwarfs (UCDs), low-mass objects of spectral types ≥M7, are known to be sources of radio flares. These typically several-minutes-long radio bursts can be up to 100% circularly polarized and have high brightness temperatures, consistent with coherent emission via the electron cyclotron maser operating in approximately kilogauss magnetic fields. Recently, the statistical properties of the bulk physical parameters that describe these UCDs have become described adequately enough to permit synthesis of the population of radio-flaring objects. For the first time, I construct a Monte Carlo simulator to model the population of these radio-flaring UCDs. This simulator is powered by Intel Secure Key (ISK), a new processor technology that uses a local entropy source to improve random number generation that has heretofore been used to improve cryptography. The results from this simulator indicate that only ∼5% of radio-flaring UCDs within the local interstellar neighborhood (radio-flaring fraction and suggest that the observed behavior is likely a result of several factors. The performance of ISK as compared to other pseudorandom number generators is also evaluated, and its potential utility for other astrophysical codes is briefly described.

  6. Deterministically Driven Avalanche Models of Solar Flares

    Science.gov (United States)

    Strugarek, Antoine; Charbonneau, Paul; Joseph, Richard; Pirot, Dorian

    2014-08-01

    We develop and discuss the properties of a new class of lattice-based avalanche models of solar flares. These models are readily amenable to a relatively unambiguous physical interpretation in terms of slow twisting of a coronal loop. They share similarities with other avalanche models, such as the classical stick-slip self-organized critical model of earthquakes, in that they are driven globally by a fully deterministic energy-loading process. The model design leads to a systematic deficit of small-scale avalanches. In some portions of model space, mid-size and large avalanching behavior is scale-free, being characterized by event size distributions that have the form of power-laws with index values, which, in some parameter regimes, compare favorably to those inferred from solar EUV and X-ray flare data. For models using conservative or near-conservative redistribution rules, a population of large, quasiperiodic avalanches can also appear. Although without direct counterparts in the observational global statistics of flare energy release, this latter behavior may be relevant to recurrent flaring in individual coronal loops. This class of models could provide a basis for the prediction of large solar flares.

  7. Flare differentially rotates sunspot on Sun's surface

    Science.gov (United States)

    Liu, Chang; Xu, Yan; Cao, Wenda; Deng, Na; Lee, Jeongwoo; Hudson, Hugh S.; Gary, Dale E.; Wang, Jiasheng; Jing, Ju; Wang, Haimin

    2016-10-01

    Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of the dense photosphere involving bulk motion. Here we report the sudden flare-induced rotation of a sunspot using the unprecedented spatiotemporal resolution of the 1.6 m New Solar Telescope, supplemented by magnetic data from the Solar Dynamics Observatory. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to ~50° h-1) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change due to the back reaction of coronal magnetic restructuring and is accompanied by a downward Poynting flux. These results have direct consequences for our understanding of energy and momentum transportation in the flare-related phenomena.

  8. Flare differentially rotates sunspot on Sun's surface

    CERN Document Server

    Liu, Chang; Cao, Wenda; Deng, Na; Lee, Jeongwoo; Hudson, Hugh S; Gary, Dale E; Wang, Jiasheng; Jing, Ju; Wang, Haimin

    2016-01-01

    Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of the dense photosphere involving bulk motion. Here we report the sudden flare-induced rotation of a sunspot using the unprecedented spatiotemporal resolution of the 1.6 m New Solar Telescope, supplemented by magnetic data from the Solar Dynamics Observatory. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to 50 deg per hr) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change due to the back reaction of coronal magnetic restructuring and is accompanied by a downward Poynting flux. These results have direct consequences for our understanding of energy and momentum transportation in the flare-related p...

  9. On Flare-Driven Global Waves

    Science.gov (United States)

    Karoff, C.

    2009-12-01

    We recently presented evidence of a strong correlation between the energy in the high-frequency part of the acoustic spectrum of the Sun and the solar X-ray flux (Karoff & Kjeldsen 2008). The discovery indicates that flares drive global oscillations in the Sun in the same way that the entire Earth is set ringing for several weeks after a major earthquake, such as the 2004 December Sumatra-Andaman one. If this indication turns out to be true we might be able to use the relation between flares and the energy in the high-frequency part of the acoustic spectrum to detect e.g. flares on the far side of the Sun and flares on other solar-like stars. But, the discovery also opens many new questions such as why is it only the high-frequency part of the acoustic spectrum that is correlated with the X-ray flux? And, is there energy enough in solar flares to drive global oscillations?

  10. Multi-spectral observations of flares

    Science.gov (United States)

    Zuccarello, F.

    2016-11-01

    Observations show that during solar flares radiation can be emitted across the entire electromagnetic spectrum, spanning from gamma rays to radio waves. These emissions, related to the conversion of magnetic energy into other forms of energy (kinetic, thermal, waves) through magnetic reconnection, are due to different physical processes that can occur in different layers of the Sun. This means that flare observations need to be carried out using instruments operating in different wave-bands in order to achieve a complete scenario of the processes going on. Taking into account that most of the radiative energy is emitted at optical and UV wavelengths, observations carried out from space, need to be complemented by observations carried out from ground-based telescopes. Nowadays, the possibility to carry on high temporal, spatial and spectral resolution from ground-based telescopes in coordinated campaigns with space-borne instruments (like, i.e., IRIS and HINODE) gives the opportunity to investigate the details of the flare emission at different wavelengths and can provide useful hints to understand these phenomena and compare observations with models. However, it is undoubted that sometimes the pointing to the flaring region is not an easy task, due to the necessity to provide the target coordinates to satellites with some hours in advance. Some problems arising from this issue will be discussed. Moreover, new projects related to flare catalogues and archives will be presented.

  11. Radiative transfer simulations of magnetar flare beaming

    CERN Document Server

    van Putten, T; Baring, M G; Wijers, R A M J

    2016-01-01

    Magnetar giant flares show oscillatory modulations in the tails of their light curves, which can only be explained via some form of beaming. The fireball model for magnetar bursts has been used successfully to fit the phase-averaged light curves of the tails of giant flares, but so far no attempts have been made to fit the pulsations. We present a relatively simple numerical model to simulate beaming of magnetar flare emission. In our simulations, radiation escapes from the base of a fireball trapped in a dipolar magnetic field, and is scattered through the optically thick magnetosphere of the magnetar until it escapes. Beaming is provided by the presence of a relativistic outflow, as well as by the geometry of the system. We find that a simple picture for the relativistic outflow is enough to create the pulse fraction and sharp peaks observed in pulse profiles of magnetar flares, while without a relativistic outflow the beaming is insufficient to explain giant flare rotational modulations.

  12. Radiative transfer simulations of magnetar flare beaming

    Science.gov (United States)

    van Putten, T.; Watts, A. L.; Baring, M. G.; Wijers, R. A. M. J.

    2016-09-01

    Magnetar giant flares show oscillatory modulations in the tails of their light curves, which can only be explained via some form of beaming. The fireball model for magnetar bursts has been used successfully to fit the phase-averaged light curves of the tails of giant flares, but so far no attempts have been made to fit the pulsations. We present a relatively simple numerical model to simulate beaming of magnetar flare emission. In our simulations, radiation escapes from the base of a fireball trapped in a dipolar magnetic field, and is scattered through the optically thick magnetosphere of the magnetar until it escapes. Beaming is provided by the presence of a relativistic outflow, as well as by the geometry of the system. We find that a simple picture for the relativistic outflow is enough to create the pulse fraction and sharp peaks observed in pulse profiles of magnetar flares, while without a relativistic outflow the beaming is insufficient to explain giant flare rotational modulations.

  13. An MHD model for magnetar giant flares

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Y.; Lin, J.; Zhang, Q. S. [Yunnan Observatories, Chinese Academy of Sciences, P.O. Box 110, Kunming, Yunnan 650011 (China); Zhang, L. [Department of Physics, Yunnan University, Kunming, Yunnan 650091 (China); Reeves, K. K. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Yuan, F., E-mail: mengy@ynao.ac.cn, E-mail: jlin@ynao.ac.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

    2014-04-10

    Giant flares on soft gamma-ray repeaters that are thought to take place on magnetars release enormous energy in a short time interval. Their power can be explained by catastrophic instabilities occurring in the magnetic field configuration and the subsequent magnetic reconnection. By analogy with the coronal mass ejection events on the Sun, we develop a theoretical model via an analytic approach for magnetar giant flares. In this model, the rotation and/or displacement of the crust causes the field to twist and deform, leading to flux rope formation in the magnetosphere and energy accumulation in the related configuration. When the energy and helicity stored in the configuration reach a threshold, the system loses its equilibrium, the flux rope is ejected outward in a catastrophic way, and magnetic reconnection helps the catastrophe develop to a plausible eruption. By taking SGR 1806–20 as an example, we calculate the free magnetic energy released in such an eruptive process and find that it is more than 10{sup 47} erg, which is enough to power a giant flare. The released free magnetic energy is converted into radiative energy, kinetic energy, and gravitational energy of the flux rope. We calculated the light curves of the eruptive processes for the giant flares of SGR 1806–20, SGR 0526–66, and SGR 1900+14, and compared them with the observational data. The calculated light curves are in good agreement with the observed light curves of giant flares.

  14. Flare differentially rotates sunspot on Sun's surface.

    Science.gov (United States)

    Liu, Chang; Xu, Yan; Cao, Wenda; Deng, Na; Lee, Jeongwoo; Hudson, Hugh S; Gary, Dale E; Wang, Jiasheng; Jing, Ju; Wang, Haimin

    2016-10-10

    Sunspots are concentrations of magnetic field visible on the solar surface (photosphere). It was considered implausible that solar flares, as resulted from magnetic reconnection in the tenuous corona, would cause a direct perturbation of the dense photosphere involving bulk motion. Here we report the sudden flare-induced rotation of a sunspot using the unprecedented spatiotemporal resolution of the 1.6 m New Solar Telescope, supplemented by magnetic data from the Solar Dynamics Observatory. It is clearly observed that the rotation is non-uniform over the sunspot: as the flare ribbon sweeps across, its different portions accelerate (up to ∼50° h(-1)) at different times corresponding to peaks of flare hard X-ray emission. The rotation may be driven by the surface Lorentz-force change due to the back reaction of coronal magnetic restructuring and is accompanied by a downward Poynting flux. These results have direct consequences for our understanding of energy and momentum transportation in the flare-related phenomena.

  15. New code for equilibriums and quasiequilibrium initial data of compact objects. II. Convergence tests and comparisons of binary black hole initial data

    CERN Document Server

    Uryu, Koji; Grandclement, Philippe

    2012-01-01

    COCAL is a code for computing equilibriums or quasiequilibrium initial data of single or binary compact objects based on finite difference methods. We present the results of supplementary convergence tests of COCAL code using time symmetric binary black hole data (Brill-Lindquist solution). Then, we compare the initial data of binary black holes on the conformally flat spatial slice obtained from COCAL and KADATH, where KADATH is a library for solving a wide class of problems in theoretical physics including relativistic compact objects with spectral methods. Data calculated from the two codes converge nicely towards each other, for close as well as largely separated circular orbits of binary black holes. Finally, as an example, a sequence of equal mass binary black hole initial data with corotating spins is calculated and compared with data in the literature.

  16. Flare forecasting based on sunspot-groups characteristics

    National Research Council Canada - National Science Library

    Contarino, Lidia; Zuccarello, Francesca; Romano, Paolo; Spadaro, Daniele; Guglielmino, Salvatore L; Battiato, Viviana

    2009-01-01

    ... accurate flare forecasting. In order to give a contribution to this aspect, we focused our attention on the characteristics that must be fulfilled by sunspot-groups in order to be flare-productive...

  17. The Origin of the Solar Flare Waiting-Time Distribution

    CERN Document Server

    Wheatland, M S

    2000-01-01

    It was recently pointed out that the distribution of times between solar flares (the flare waiting-time distribution) follows a power law, for long waiting times. Based on 25 years of soft X-ray flares observed by Geostationary Operational Environmental Satellite (GOES) instruments it is shown that 1. the waiting-time distribution of flares is consistent with a time-dependent Poisson process, and 2. the fraction of time the Sun spends with different flaring rates approximately follows an exponential distribution. The second result is a new phenomenological law for flares. It is shown analytically how the observed power-law behavior of the waiting times originates in the exponential distribution of flaring rates. These results are argued to be consistent with a non-stationary avalanche model for flares.

  18. H-alpha macrospicules - Identification with EUV macrospicules and with flares in X-ray bright points

    Science.gov (United States)

    Moore, R. L.; Tang, F.; Bohlin, J. D.; Golub, L.

    1977-01-01

    The paper presents observational evidence that two newly observed transient solar phenomena, EUV macrospicules and X-ray bright-point flares, are closely related. Time-lapse H-alpha filtergram observations of the limb in quiet regions show small surgelike eruptions called H-alpha macrospicules. From the similarity of H-alpha macrospicules and EUV macrospicules, and from comparison of simultaneous H-alpha and He II 304 A observations, we conclude that H-alpha macrospicules are EUV macrospicules viewed in H-alpha, although most EUV macrospicules are too faint in H-alpha to appear on H-alpha filtergrams of normal exposure. From comparison of simultaneous X-ray and H-alpha observations of flares in X-ray bright points situated on the limb, we show that flares in X-ray bright points often produce H-alpha macrospicules.

  19. Analysis of the 9th November 1990 flare

    Indian Academy of Sciences (India)

    Anita Joshi; Wahab Uddin

    2000-09-01

    In this paper we present complete two-dimensional measurements of the observed brightness of the 9th November 1990 flare, using a PDS microdensitometer scanner and image processing software MIDAS. The resulting isophotal contour maps, were used to describe morphological-cum-temporal behaviour of the flare and also the kernels of the flare. Correlation of the flare with SXR and MW radiations were also studied.

  20. Microwave View on Particle Acceleration in Flares

    CERN Document Server

    Fleishman, Gregory D

    2013-01-01

    The thermal-to-nonthermal partition was found to vary greatly from one flare to another resulting in a broad variety of cases from 'heating without acceleration' to 'acceleration without heating'. Recent analysis of microwave data of these differing cases suggests that a similar acceleration mechanism, forming a power-law nonthermal tail up to a few MeV or even higher, operates in all the cases. However, the level of this nonthermal spectrum compared to the original thermal distribution differs significantly from one case to another, implying a highly different thermal-to-nonthermal energy partition in various cases. This further requires a specific mechanism capable of extracting the charged particles from the thermal pool and supplying them to a bulk acceleration process to operate in flares \\textit{in addition} to the bulk acceleration process itself, which, in contrast, efficiently accelerates the seed particles, while cannot accelerate the thermal particles. Within this 'microwave' view on the flare ener...

  1. Remote Oscillatory responses to a solar flare

    CERN Document Server

    Andic, Aleksandra

    2013-01-01

    The processes governing energy storage and release in the Sun are both related to the solar magnetic field. We demonstrate the existence of a magnetic connection between energy released caused by a flare and increased oscillatory power in the lower solar atmosphere. The oscillatory power in active regions tends to increase in response to explosive events at a different location, but not in the region itself. We carry out timing studies and show that this is probably caused by a large scale magnetic connection between the regions, and not a globally propagating wave. We show that oscillations tend to exist in longer lived wave trains at short periods (P< 200s) at the time of a flare. This may be a mechanism by which flare energy can be redistributed throughout the solar atmosphere.

  2. Image watermarking against lens flare effects

    Science.gov (United States)

    Chotikawanid, Piyanart; Amornraksa, Thumrongrat

    2017-02-01

    Lens flare effects in various photo and camera software nowadays can partially or fully damage the watermark information within the watermarked image. We propose in this paper a spatial domain based image watermarking against lens flare effects. The watermark embedding is based on the modification of the saturation color component in HSV color space of a host image. For watermark extraction, a homomorphic filter is used to predict the original embedding component from the watermarked component, and the watermark is blindly recovered by differentiating both components. The watermarked image's quality is evaluated by wPSNR, while the extracted watermark's accuracy is evaluated by NC. The experimental results against various types of lens flare effects from both computer software and mobile application showed that our proposed method outperformed the previous methods.

  3. High Energy Neutrinos from Recent Blazar Flares

    CERN Document Server

    Halzen, Francis

    2016-01-01

    The energy density of cosmic neutrinos measured by IceCube matches the one observed by Fermi in extragalactic photons that predominantly originate in blazars. This has inspired attempts to match Fermi sources with IceCube neutrinos. A spatial association combined with a coincidence in time with a flaring source may represent a smoking gun for the origin of the IceCube flux. In June 2015, the Fermi Large Area Telescope observed an intense flare from blazar 3C 279 that exceeded the steady flux of the source by a factor of forty for the duration of a day. We show that IceCube is likely to observe neutrinos, if indeed hadronic in origin, in data that are still blinded at this time. We also discuss other opportunities for coincident observations that include a recent flare from blazar 1ES 1959+650 that previously produced an intriguing coincidence with AMANDA observations.

  4. Measurements of Absolute Abundances in Solar Flares

    CERN Document Server

    Warren, Harry P

    2013-01-01

    We present measurements of elemental abundances in solar flares with the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO). EVE observes both high temperature Fe emission lines (Fe XV-Fe XXIV) and continuum emission from thermal bremsstrahlung that is proportional to the abundance of H. By comparing the relative intensities of line and continuum emission it is possible to determine the enrichment of the flare plasma relative to the composition of the photosphere. This is the first ionization potential or FIP bias ($f$). Since thermal bremsstrahlung at EUV wavelengths is relatively insensitive to the electron temperature, it is important to account for the distribution of electron temperatures in the emitting plasma. We accomplish this by using the observed spectra to infer the differential emission measure distribution and FIP bias simultaneously. In each of the 21 flares that we analyze we find that the observed composition is close to photospheric. The mean FIP bias in our sample is $...

  5. Magnetic Field Amplification and Blazar Flares

    CERN Document Server

    Chen, Xuhui; Fossati, Giovanni; Pohl, Martin

    2013-01-01

    Recent multiwavelength observations of PKS 0208-512 by SMARTS, Fermi, and Swift revealed that gamma-ray and optical light curves of this flat spectrum radio quasars are highly correlated, but with an exception of one large optical flare having no corresponding gamma-ray activity or even detection. On the other hand, recent advances in SNRs observations and plasma simulations both reveal that magnetic field downstream of astrophysical shocks can be largely amplified beyond simple shock compression. These amplifications, along with their associated particle acceleration, might contribute to blazar flares, including the peculiar flare of PKS 0208-512. Using our time dependent multizone blazar emission code, we evaluate several scenarios that may represent such phenomena. This code combines Monte Carlo method that tracks the radiative processes including inverse Compton scattering, and Fokker-Planck equation that follows the cooling and acceleration of particles. It is a comprehensive time dependent code that ful...

  6. SU-E-J-58: Comparison of Conformal Tracking Methods Using Initial, Adaptive and Preceding Image Frames for Image Registration

    Energy Technology Data Exchange (ETDEWEB)

    Teo, P; Guo, K; Alayoubi, N; Kehler, K; Pistorius, S [CancerCare Manitoba, Winnipeg, MB (Canada)

    2015-06-15

    Purpose: Accounting for tumor motion during radiation therapy is important to ensure that the tumor receives the prescribed dose. Increasing the field size to account for this motion exposes the surrounding healthy tissues to unnecessary radiation. In contrast to using motion-encompassing techniques to treat moving tumors, conformal radiation therapy (RT) uses a smaller field to track the tumor and adapts the beam aperture according to the motion detected. This work investigates and compares the performance of three markerless, EPID based, optical flow methods to track tumor motion with conformal RT. Methods: Three techniques were used to track the motions of a 3D printed lung tumor programmed to move according to the tumor of seven lung cancer patients. These techniques utilized a multi-resolution optical flow algorithm as the core computation for image registration. The first method (DIR) registers the incoming images with an initial reference frame, while the second method (RFSF) uses an adaptive reference frame and the third method (CU) uses preceding image frames for registration. The patient traces and errors were evaluated for the seven patients. Results: The average position errors for all patient traces were 0.12 ± 0.33 mm, −0.05 ± 0.04 mm and −0.28 ± 0.44 mm for CU, DIR and RFSF method respectively. The position errors distributed within 1 standard deviation are 0.74 mm, 0.37 mm and 0.96 mm respectively. The CU and RFSF algorithms are sensitive to the characteristics of the patient trace and produce a wider distribution of errors amongst patients. Although the mean error for the DIR method is negatively biased (−0.05 mm) for all patients, it has the narrowest distribution of position error, which can be corrected using an offset calibration. Conclusion: Three techniques of image registration and position update were studied. Using direct comparison with an initial frame yields the best performance. The authors would like to thank Dr.YeLin Suh for

  7. The Flare-ona of EK Draconis

    Science.gov (United States)

    Ayres, Thomas R.

    2015-07-01

    EK Draconis (HD 129333: G1.5 V) is a well-known young (50 Myr) solar analog. In 2012, Hubble Space Telescope returned to EK Dra to follow up a far-ultraviolet (FUV) SNAPshot visit by Cosmic Origins Spectrograph (COS) two years earlier. The brief SNAP pointing had found surprisingly redshifted, impulsively variable subcoronal “hot-line” emission of Si iv 1400 Å (T ˜ 8 × 104 K). Serendipitously, the 2012 follow-on program witnessed one of the largest FUV flares ever recorded on a sunlike star, which again displayed strong redshifts (downflows) of 30-40 km s-1, even after compensating for small systematics in the COS velocity scales, uncovered through a cross-calibration by Space Telescope Imaging Spectrograph (STIS). The (now reduced, but still substantial) ˜10 km s-1 hot-line redshifts outside the flaring interval did not vary with rotational phase, so cannot be caused by “Doppler imaging” (bright surface patches near a receding limb). Density diagnostic O iv] 1400 Å multiplet line ratios of EK Dra suggest ne ˜ 1011 cm-3, an order of magnitude larger than in low-activity solar twin α Centauri A, but typical of densities inferred in large stellar soft X-ray events. The self-similar FUV hot-line profiles between the flare decay and the subsequent more quiet periods, and the unchanging but high densities, reinforce a long-standing idea that the coronae of hyperactive dwarfs are flaring all the time, in a scale-free way; a flare-ona if you will. In this picture, the subsonic hot-line downflows probably are a byproduct of the post-flare cooling process, something like “coronal rain” on the Sun. All in all, the new STIS/COS program documents a complex, energetic, dynamic outer atmosphere of the young sunlike star.

  8. Comparison of a Commonwealth-initiated regional radiation oncology facility in Toowoomba with a Queensland Health facility.

    Science.gov (United States)

    Poulsen, M; Middleton, M; McQuitty, S; Ramsay, J; Gogna, K; Martin, J; Khoo, E; Wong, W; Fairweather, R; Walpole, E

    2010-08-01

    The aim was to compare a private Commonwealth-initiated regional radiation oncology facility in Toowoomba with a Queensland Health facility (QHF) in Brisbane. The comparison concentrated on staffing, case mix and operational budgets, but was not able to look at changes in access to services. Data were collected from the two facilities from January 2008 to June 2008 inclusive. A number of factors were compared, including case mix, staffing levels, delay times for treatment, research, training and treatment costs. The case mix between the two areas was similar with curative treatments making up just over half the work load in both centres and two-thirds the work being made up of cancers of breast and prostate. Staffing levels were leaner in Toowoomba, especially in the areas of nursing, administration and trial coordinators. Research activity was slightly higher in Toowoomba. The average medicare cost per treatment course was similar in both centres ($5000 per course). Total costs of an average treatment including patient, State and Commonwealth costs, showed a 30% difference in costing favouring Toowoomba. This regional radiation oncology centre has provided state-of-the-art cancer care that is close to home for patients living in the Darling Downs region. Both public and private patients have been treated with modest costs to the patient and significant savings to QH. The case mix is similar to the QHF, and there has been significant activity in clinical research. A paperless working environment is one factor that has allowed staffing levels to be reduced. Ongoing support from Governments are required if private facilities are to participate in important ongoing staff training.

  9. Flares in the X-ray source EXO 2030 + 375

    Science.gov (United States)

    Apparao, Krishna M. V.

    1991-01-01

    Six X-ray flares were observed in the source EXO 2030 + 375 with an average time interval of about 4 hr between the flares. It is shown here that the flares can be due to Rayleigh-Taylor instabilities near the magnetospheric boundary of the neutron star when it reaches the equilibrium period.

  10. MWA targeted campaign of nearby, flaring M dwarf stars

    Science.gov (United States)

    Lynch, C.; Murphy, T.; Kaplan, D. L.

    2017-01-01

    Flaring activity is a common characteristic of magnetically active stellar systems. Flare events produce emission throughout the electromagnetic spectrum, implying a range of physical processes. Early 100 - 200 MHz observations of M dwarf flare stars detected bright (>100 mJy) flares with occurrence rates between 0.06 - 0.8 flares per hour. These rates imply that observing 100 - 200 MHz flares from M dwarf stars is fairly easy with many detections expected for modern low-frequency telescopes. However, long observational campaigns using these modern telescopes have not reproduced these early detections. This could be because the rates are over estimated and contaminated by radio frequency interference. Recently Lynch et al. (submitted) detected four flares from UV Ceti at 154 MHz using the Murchison Widefield Array. The flares have flux densities between 10-65 mJy -- a factor of 100 fainter than most flares in the literature at these frequencies -- and are only detected in circular polarization. The flare rates for these newly detected flares are roughly consistent with earlier rates however the uncertainties are large. Building off this result we propose a 102 hour survey of the closet six M dwarf stars with observed magnetic activity traced in X-rays and 100 - 200 MHz emission. The rates measured from this survey would inform the duration required for future blind surveys for flares from M dwarf stars.

  11. Absorption events associated with solar flares

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    During the upward period of solar cycle 23, the imaging riometer at Zhongshan, Antarctica (geomag. lat. 74.5°S) was used to study the solar proton events and the X-ray solar flares which are associated with the absorption events. In our study, the relationship between the absorption intensity and X-ray flux is found in a power form which is consistent with the theoretical result. The imaging riometer absorption data at Ny-?lesund, Svalbard reconfirm the above relationship. We also argue that only M-class flares can generate a significant daytime absorption.

  12. Universality in solar flare and earthquake occurrence.

    Science.gov (United States)

    de Arcangelis, L; Godano, C; Lippiello, E; Nicodemi, M

    2006-02-10

    Earthquakes and solar flares are phenomena involving huge and rapid releases of energy characterized by complex temporal occurrence. By analyzing available experimental catalogs, we show that the stochastic processes underlying these apparently different phenomena have universal properties. Namely, both problems exhibit the same distributions of sizes, interoccurrence times, and the same temporal clustering: We find after flare sequences with power law temporal correlations as the Omori law for seismic sequences. The observed universality suggests a common approach to the interpretation of both phenomena in terms of the same driving physical mechanism.

  13. Slipping Magnetic Reconnection of Flux-rope Structures as a Precursor to an Eruptive X-class Solar Flare

    Science.gov (United States)

    Li, Ting; Yang, Kai; Hou, Yijun; Zhang, Jun

    2016-10-01

    We present the quasi-periodic slipping motion of flux-rope structures prior to the onset of an eruptive X-class flare on 2015 March 11, obtained by the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory. The slipping motion occurred at the north part of the flux rope and seemed to successively peel off the flux rope. The speed of the slippage was 30-40 km s-1, with an average period of 130 ± 30 s. The Si iv λ1402.77 line showed a redshift of 10-30 km s-1 and a line width of 50-120 km s-1 at the west legs of slipping structures, indicative of reconnection downflow. The slipping motion lasted about 40 minutes, and the flux rope started to rise up slowly at the late stage of the slippage. Then an X2.1 flare was initiated, and the flux rope was impulsively accelerated. One of the flare ribbons swept across a negative-polarity sunspot, and the penumbral segments of the sunspot decayed rapidly after the flare. We studied the magnetic topology at the flaring region, and the results showed the existence of a twisted flux rope, together with quasi-separatrix layer (QSL) structures binding the flux rope. Our observations imply that quasi-periodic slipping magnetic reconnection occurs along the flux-rope-related QSLs in the preflare stage, which drives the later eruption of the flux rope and the associated flare.

  14. OBSERVATIONS OF A SERIES OF FLARES AND ASSOCIATED JET-LIKE ERUPTIONS DRIVEN BY THE EMERGENCE OF TWISTED MAGNETIC FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Eun-Kyung; Yurchyshyn, Vasyl; Kim, Sujin; Cho, Kyung-Suk; Kumar, Pankaj; Kim, Yeon-Han [Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 305-348 (Korea, Republic of); Park, Sung-Hong [Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing (IAASARS), National Observatory of Athens, Penteli 15236 (Greece); Chae, Jongchul; Yang, Heesu; Cho, Kyuhyoun; Song, Donguk, E-mail: eklim@kasi.re.kr [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2016-01-20

    We studied temporal changes of morphological and magnetic properties of a succession of four confined flares followed by an eruptive flare using the high-resolution New Solar Telescope (NST) operating at the Big Bear Solar Observatory (BBSO) and Helioseismic and Magnetic Imager (HMI) magnetograms and Atmospheric Image Assembly (AIA) EUV images provided by the Solar Dynamics Observatory (SDO). From the NST/Hα and the SDO/AIA 304 Å observations we found that each flare developed a jet structure that evolved in a manner similar to evolution of the blowout jet: (1) an inverted-Y-shaped jet appeared and drifted away from its initial position; (2) jets formed a curtain-like structure that consisted of many fine threads accompanied by subsequent brightenings near the footpoints of the fine threads; and finally, (3) the jet showed a twisted structure visible near the flare maximum. Analysis of the HMI data showed that both the negative magnetic flux and the magnetic helicity have been gradually increasing in the positive-polarity region, indicating the continuous injection of magnetic twist before and during the series of flares. Based on these results, we suggest that the continuous emergence of twisted magnetic flux played an important role in producing successive flares and developing a series of blowout jets.

  15. Thermo-hydraulic modeling of flow in flare systems

    OpenAIRE

    Meindinyo, Remi-Erempagamo T.

    2012-01-01

    Flare systems play a major role in the safety of Oil and Gas installations by serving as outlets for emergency pressure relief in case of process upsets. Accurate and reliable estimation of system thermo-hydraulic parameters, especially system back-pressure is critical to the integrity of a flare design. FlareNet (Aspen Flare System Analyzer Version 7) is a steady state simulation tool tailored for flare system design and has found common use today. But design based on steady state modelin...

  16. The flaring HI disk of the nearby spiral galaxy NGC 2683

    CERN Document Server

    Vollmer, B; Ibata, R

    2015-01-01

    New deep VLA D array HI observations of the highly inclined nearby spiral galaxy NGC 2683 are presented. Archival C array data were processed and added to the new observations. To investigate the 3D structure of the atomic gas disk, we made different 3D models for which we produced model HI data cubes. The main ingredients of our best-fit model are (i) a thin disk inclined by 80 degrees; (ii) a crude approximation of a spiral and/or bar structure by an elliptical surface density distribution of the gas disk; (iii) a slight warp in inclination; (iv) an exponential flare; and (v) a low surface-density gas ring. The slope of NGC 2683's flare is comparable, but somewhat steeper than those of other spiral galaxies. NGC 2683's maximum height of the flare is also comparable to those of other galaxies. On the other hand, a saturation of the flare is only observed in NGC 2683. Based on the comparison between the high resolution model and observations, we exclude the existence of an extended atomic gas halo around the ...

  17. Thermal and Non-Thermal Emission in Two-Ribbon Flares

    Science.gov (United States)

    Warren, H.

    2004-05-01

    The observation that in many flares there is a good correlation between the soft X-ray emission and the time-integrated non-thermal emission --- the Neupert effect --- indicates a strong link between magnetic reconnection and particle acceleration. We present hydrodynamic simulations of flare loops heated by precipitating energetic electrons. Instead of representing a flare as a single loop, we model it as a succession of independently heated, small-scale filaments. We find that to reproduce the observed thermal emission the energy in the injected electrons must be proportional to the soft X-ray flux, not the derivative of the soft X-ray flux as suggested by the Neupert effect. Comparisons between the simulations and GOES and RHESSI observations indicates that there is not sufficient energy in the non-thermal electrons to account for the thermal emission observed in a large, long duration flare. This suggests that there must be in situ heating of coronal plasma as well as particle acceleration during magnetic reconnection.

  18. Temporal and spatial relationship of flare signatures and the force-free coronal magnetic field

    CERN Document Server

    Thalmann, Julia K; Su, Yang

    2016-01-01

    We investigate the plasma and magnetic environment of active region NOAA 11261 on 2 August 2011 around a GOES M1.4 flare/CME (SOL2011-08-02T06:19). We compare coronal emission at (extreme) ultraviolet and X-ray wavelengths, using SDO AIA and RHESSI images, in order to identify the relative timing and locations of reconnection-related sources. We trace flare ribbon signatures at ultraviolet wavelengths, in order to pin down the intersection of previously reconnected flaring loops at the lower solar atmosphere. These locations are used to calculate field lines from 3D nonlinear force-free magnetic field models, established on the basis of SDO HMI photospheric vector magnetic field maps. With this procedure, we analyze the quasi-static time evolution of the coronal model magnetic field previously involved in magnetic reconnection. This allows us, for the first time, to estimate the elevation speed of the current sheet's lower tip during an on-disk observed flare, as a few kilometers per second. Comparison to pos...

  19. A solar tornado triggered by flares?

    CERN Document Server

    Panesar, N K; Tiwari, S K; Low, B C

    2012-01-01

    Solar tornados are dynamical, conspicuously helical magnetic structures mainly observed as a prominence activity. We investigate and propose a triggering mechanism for the solar tornado observed in a prominence cavity by SDO/AIA on September 25, 2011. High-cadence EUV images from the SDO/AIA and the Ahead spacecraft of STEREO/EUVI are used to correlate three flares in the neighbouring active-region (NOAA 11303), and their EUV waves, with the dynamical developments of the tornado. The timings of the flares and EUV waves observed on-disk in 195\\AA\\ are analyzed in relation to the tornado activities observed at the limb in 171\\AA. Each of the three flares and its related EUV wave occurred within 10 hours of the onset of the tornado. They have an observed causal relationship with the commencement of activity in the prominence where the tornado develops. Tornado-like rotations along the side of the prominence start after the second flare. The prominence cavity expands with acceleration of tornado motion after the ...

  20. Do all Flares have White Light Emission?

    CERN Document Server

    Jess, D B; Crockett, P J; Keenan, F P

    2008-01-01

    High-cadence, multiwavelength optical observations of a solar active region (NOAA 10969), obtained with the Swedish Solar Telescope, are presented. Difference imaging of white light continuum data reveals a white light brightening, 2 min in duration, linked to a co-temporal and co-spatial C2.0 flare event. The flare kernel observed in the white light images has a diameter of 300 km, thus rendering it below the resolution limit of most space-based telescopes. Continuum emission is present only during the impulsive stage of the flare, with the effects of chromospheric emission subsequently delayed by approximately 2 min. The localized flare emission peaks at 300% above the quiescent flux. This large, yet tightly confined, increase in emission is only resolvable due to the high spatial resolution of the Swedish Solar Telescope. An investigation of the line-of-sight magnetic field derived from simultaneous MDI data shows that the continuum brightening is located very close to a magnetic polarity inversion line. A...

  1. Measurements of Absolute Abundances in Solar Flares

    Science.gov (United States)

    Warren, Harry P.

    2014-05-01

    We present measurements of elemental abundances in solar flares with the EUV Variability Experiment (EVE) on the Solar Dynamics Observatory. EVE observes both high temperature Fe emission lines (Fe XV-Fe XXIV) and continuum emission from thermal bremsstrahlung that is proportional to the abundance of H. By comparing the relative intensities of line and continuum emission it is possible to determine the enrichment of the flare plasma relative to the composition of the photosphere. This is the first ionization potential or FIP bias (f). Since thermal bremsstrahlung at EUV wavelengths is relatively insensitive to the electron temperature, it is important to account for the distribution of electron temperatures in the emitting plasma. We accomplish this by using the observed spectra to infer the differential emission measure distribution and FIP bias simultaneously. In each of the 21 flares that we analyze we find that the observed composition is close to photospheric. The mean FIP bias in our sample is f = 1.17 ± 0.22. This analysis suggests that the bulk of the plasma evaporated during a flare comes from deep in the chromosphere, below the region where elemental fractionation occurs.

  2. The Relation between Solar Eruption Topologies and Observed Flare Features I: Flare Ribbons

    CERN Document Server

    Savcheva, A; McKillop, S; McCauley, P; Hanson, E; Su, Y; Werner, E; DeLuca, E E

    2015-01-01

    In this paper we present a topological magnetic field investigation of seven two-ribbon flares in sigmoidal active regions observed with Hinode, STEREO, and SDO. We first derive the 3D coronal magnetic field structure of all regions using marginally unstable 3D coronal magnetic field models created with the flux rope insertion method. The unstable models have been shown to be a good model of the flaring magnetic field configurations. Regions are selected based on their pre-flare configurations along with the appearance and observational coverage of flare ribbons, and the model is constrained using pre-flare features observed in extreme ultraviolet and X-ray passbands. We perform a topology analysis of the models by computing the squashing factor, Q, in order to determine the locations of prominent quasi-separatrix layers (QSLs). QSLs from these maps are compared to flare ribbons at their full extents. We show that in all cases the straight segments of the two J-shaped ribbons are matched very well by the flux...

  3. Optical flares and flaring oscillations on the M-type eclipsing binary CU Cnc

    CERN Document Server

    -B., Qian S; Zhu, L -Y; Liu, L; Liao, W -P; Zhao, E -G; He, J -J; Li, L -J; Li, K; Dai, Z -B

    2012-01-01

    We report here the discovery of an optical flare observed in R band from the red-dwarf eclipsing binary CU Cnc whose component stars are at the upper boundary of full convection (M1=0.43 and M2=0.4M0, M0 is the solar mass). The amplitude of the flare is the largest among those detected in R band (~0.52mag) and the duration time is about 73 minutes. As those observed on the Sun, quasi-periodic oscillations were seen during and after the flare. Three more R-band flares were found by follow up monitoring. In total, this binary was monitored photometrically by using R filter for 79.9 hours, which reveals a R-band flare rate about 0.05 flares per hour. These detections together with other strong chromospheric and coronal activities, i.e., very strong H_alpha and H_beta emission features and an EUV and X-ray source, indicate that it has very strong magnetic activity. Therefore, the apparent faintness (~1.4 magnitude in V) of CU Cnc compared with other single red dwarfs of the same mass can be plausibly explained by...

  4. GRB Flares: A New Detection Algorithm, Previously Undetected Flares, and Implications on GRB Physics

    CERN Document Server

    Swenson, C A

    2013-01-01

    Flares in GRB light curves have been observed since shortly after the discovery of the first GRB afterglow. However, it was not until the launch of the Swift satellite that it was realized how common flares are, appearing in nearly 50% of all X-ray afterglows as observed by the XRT instrument. The majority of these observed X-ray flares are easily distinguishable by eye and have been measured to have up to as much fluence as the original prompt emission. Through studying large numbers of these X-ray flares it has been determined that they likely result from a distinct emission source different than that powering the GRB afterglow. These findings could be confirmed if similar results were found using flares in other energy ranges. However, until now, the UVOT instrument on Swift seemed to have observed far fewer flares in the UV/optical than were seen in the X-ray. This was primarily due to poor sampling and data being spread across multiple filters, but a new optimal co-addition and normalization of the UVOT ...

  5. Field Measurements of Black Carbon Yields from Gas Flaring.

    Science.gov (United States)

    Conrad, Bradley M; Johnson, Matthew R

    2017-02-07

    Black carbon (BC) emissions from gas flaring in the oil and gas industry are postulated to have critical impacts on climate and public health, but actual emission rates remain poorly characterized. This paper presents in situ field measurements of BC emission rates and flare gas volume-specific BC yields for a diverse range of flares. Measurements were performed during a series of field campaigns in Mexico and Ecuador using the sky-LOSA optical measurement technique, in concert with comprehensive Monte Carlo-based uncertainty analyses. Parallel on-site measurements of flare gas flow rate and composition were successfully performed at a subset of locations enabling direct measurements of fuel-specific BC yields from flares under field conditions. Quantified BC emission rates from individual flares spanned more than 4 orders of magnitude (up to 53.7 g/s). In addition, emissions during one notable ∼24-h flaring event (during which the plume transmissivity dropped to zero) would have been even larger than this maximum rate, which was measured as this event was ending. This highlights the likely importance of superemitters to global emission inventories. Flare gas volume-specific BC yields were shown to be strongly correlated with flare gas heating value. A newly derived correlation fitting current field data and previous lab data suggests that, in the context of recent studies investigating transport of flare-generated BC in the Arctic and globally, impacts of flaring in the energy industry may in fact be underestimated.

  6. MOST Observations of Our Nearest Neighbor: Flares on Proxima Centauri

    Science.gov (United States)

    Davenport, James R. A.; Kipping, David M.; Sasselov, Dimitar; Matthews, Jaymie M.; Cameron, Chris

    2016-10-01

    We present a study of white-light flares from the active M5.5 dwarf Proxima Centauri using the Canadian microsatellite Microvariability and Oscillations of STars. Using 37.6 days of monitoring data from 2014 to 2015, we have detected 66 individual flare events, the largest number of white-light flares observed to date on Proxima Cen. Flare energies in our sample range from 1029 to 1031.5 erg. The flare rate is lower than that of other classic flare stars of a similar spectral type, such as UV Ceti, which may indicate Proxima Cen had a higher flare rate in its youth. Proxima Cen does have an unusually high flare rate given its slow rotation period, however. Extending the observed power-law occurrence distribution down to 1028 erg, we show that flares with flux amplitudes of 0.5% occur 63 times per day, while superflares with energies of 1033 erg occur ∼8 times per year. Small flares may therefore pose a great difficulty in searches for transits from the recently announced 1.27 M ⊕ Proxima b, while frequent large flares could have significant impact on the planetary atmosphere.

  7. Flare Characteristics from X-ray Light Curves

    Science.gov (United States)

    Gryciuk, M.; Siarkowski, M.; Sylwester, J.; Gburek, S.; Podgorski, P.; Kepa, A.; Sylwester, B.; Mrozek, T.

    2017-06-01

    A new methodology is given to determine basic parameters of flares from their X-ray light curves. Algorithms are developed from the analysis of small X-ray flares occurring during the deep solar minimum of 2009, between Solar Cycles 23 and 24, observed by the Polish Solar Photometer in X-rays (SphinX) on the Complex Orbital Observations Near-Earth of Activity of the Sun-Photon (CORONAS- Photon) spacecraft. One is a semi-automatic flare detection procedure that gives start, peak, and end times for single ("elementary") flare events under the assumption that the light curve is a simple convolution of a Gaussian and exponential decay functions. More complex flares with multiple peaks can generally be described by a sum of such elementary flares. Flare time profiles in the two energy ranges of SphinX (1.16 - 1.51 keV, 1.51 - 15 keV) are used to derive temperature and emission measure as a function of time during each flare. The result is a comprehensive catalogue - the SphinX Flare Catalogue - which contains 1600 flares or flare-like events and is made available for general use. The methods described here can be applied to observations made by Geosynchronous Operational Environmental Satellites (GOES), the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and other broad-band spectrometers.

  8. Ultraviolet and radio flares from UX Arietis and HR 1099

    Science.gov (United States)

    Lang, Kenneth R.; Willson, Robert F.

    1988-01-01

    Simultaneous observations of the RS CVn systems UX Ari and HR 1099 with the IUE satellite and the VLA are presented. Flaring activity is observed at ultraviolet wavelengths with the IUE when none is detected at radio wavelengths with the VLA. Radio flares with no detectable ultraviolet activity have also been observed. Thus, flares in the two spectral regions are either uncorrelated or weakly correlated. The flaring emission probably originates in different regions at the two wavelengths. Radio flares from RS CVn stars may originate in sources that are larger than, or comparable to, a star in size. This is in sharp contrast to compact, coherent radio flares from dwarf M stars. The ultraviolet flares from RS CVn stars probably originate in sources that are smaller than a component star.

  9. Solar flare prediction using highly stressed longitudinal magnetic field parameters

    Institute of Scientific and Technical Information of China (English)

    Xin Huang; Hua-Ning Wang

    2013-01-01

    Three new longitudinal magnetic field parameters are extracted from SOHO/MDI magnetograms to characterize properties of the stressed magnetic field in active regions,and their flare productivities are calculated for 1055 active regions.We find that the proposed parameters can be used to distinguish flaring samples from non-flaring samples.Using the long-term accumulated MDI data,we build the solar flare prediction model by using a data mining method.Furthermore,the decision boundary,which is used to divide flaring from non-flaring samples,is determined by the decision tree algorithm.Finally,the performance of the prediction model is evaluated by 10-fold cross validation technology.We conclude that an efficient solar flare prediction model can be built by the proposed longitudinal magnetic field parameters with the data mining method.

  10. X-ray Flares of EV Lac: Statistics, Spectra, Diagnostics

    CERN Document Server

    Huenemoerder, David P; Testa, Paola; Drake, Jeremy J; Osten, Rachel A; Reale, Fabio

    2010-01-01

    We study the spectral and temporal behavior of X-ray flares from the active M-dwarf EV Lac in 200 ks of exposure with the Chandra/HETGS. We derive flare parameters by fitting an empirical function which characterizes the amplitude, shape, and scale. The flares range from very short (<1 ks) to long (10 ks) duration events with a range of shapes and amplitudes for all durations. We extract spectra for composite flares to study their mean evolution and to compare flares of different lengths. Evolution of spectral features in the density-temperature plane shows probable sustained heating. The short flares are significantly hotter than the longer flares. We determined an upper limit to the Fe K fluorescent flux, the best fit value being close to what is expected for compact loops.

  11. Study of sunspot group morphological variations leading to flaring events

    CERN Document Server

    Korsos, M B; Ludmany, A

    2014-01-01

    It is widely assumed that the most probable sites of flare occurrences are the locations of high horizontal magnetic field gradients in the active regions. Instead of magnetograms the present work checks this assumption by using sunspot data, the targeted phenomenon is the pre-flare behaviour of the strong horizontal gradients of the magnetic field at the location of the flare. The empirical basis of the work is the SDD (SOHO/MDI-Debrecen sunspot Data) sunspot catalogue. Case studies of two active regions and five X-flares have been carried out to find possible candidates for pre-flare signatures. It has been found that the following properties of the temporal variations of horizontal magnetic field gradient are promising for flare forecast: the speed of its growth, its maximal value, its decrease after the maximum until the flare and the rate of its fluctuation.

  12. The CME - Flare Relationship During The Present Solar Cycle

    Science.gov (United States)

    Shaltout, M.; Mahrous, A.; Youssef, M.; Mawad, R.; El-Naway, M.

    The relation between the Coronal mass Ejection CME and the solar flare is statistically studied More than ten thousand CME events observed by SOHO LASCO during the period 1996-2005 have been analyzed The soft x-ray flux measurements provided by the Geostationary Operational Environmental Satellite GEOS recorded more than twenty thousand flares in the same time period The data have been filtered under certain temporal and spatial conditions to select the CME-flare associated events The results show that the lift-off time of CME-flare associated events having a time interval within the range 0 4 sim 0 6 hour after the occurrence time of associated flares The CME events have been classified into a certain categories according to its energy E CME and the classes of the associated flares In addition we found a good linear correlation between the E CME and the x-ray flux of associated flare events

  13. A CIRCULAR-RIBBON SOLAR FLARE FOLLOWING AN ASYMMETRIC FILAMENT ERUPTION

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chang; Deng, Na; Lee, Jeongwoo; Wang, Haimin [Space Weather Research Laboratory, New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982 (United States); Liu, Rui [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026 (China); Pariat, Étienne [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universits, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, F-92190 Meudon (France); Wiegelmann, Thomas [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, D-37077 Göttingen (Germany); Liu, Yang [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States); Kleint, Lucia, E-mail: chang.liu@njit.edu [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch (Switzerland)

    2015-10-20

    The dynamic properties of flare ribbons and the often associated filament eruptions can provide crucial information on the flaring coronal magnetic field. This Letter analyzes the GOES-class X1.0 flare on 2014 March 29 (SOL2014-03-29T17:48), in which we found an asymmetric eruption of a sigmoidal filament and an ensuing circular flare ribbon. Initially both EUV images and a preflare nonlinear force-free field model show that the filament is embedded in magnetic fields with a fan-spine-like structure. In the first phase, which is defined by a weak but still increasing X-ray emission, the western portion of the sigmoidal filament arches upward and then remains quasi-static for about five minutes. The western fan-like and the outer spine-like fields display an ascending motion, and several associated ribbons begin to brighten. Also found is a bright EUV flow that streams down along the eastern fan-like field. In the second phase that includes the main peak of hard X-ray (HXR) emission, the filament erupts, leaving behind two major HXR sources formed around its central dip portion and a circular ribbon brightened sequentially. The expanding western fan-like field interacts intensively with the outer spine-like field, as clearly seen in running difference EUV images. We discuss these observations in favor of a scenario where the asymmetric eruption of the sigmoidal filament is initiated due to an MHD instability and further facilitated by reconnection at a quasi-null in corona; the latter is in turn enhanced by the filament eruption and subsequently produces the circular flare ribbon.

  14. Five years of gas flaring by country, oil field or flare observed by the Suomi NPP satellite

    Science.gov (United States)

    Zhizhin, M. N.; Elvidge, C.; Baugh, K.; Hsu, F. C.

    2016-12-01

    We will present a new methodology and the resulting interactive map and statistical estimates of flared gas volumes in 2012-2016 using multispectral infrared images from VIIRS radiometer at the Suomi NPP satellite. The high temperature gas flares are detected at the night side of the Earth with the Nightfire algorithm. Gas flares are distinct from biomass burning and industrial heat sources because they have higher temperatures. Sums of the radiative heat from the detected flares are calibrated with country-level flared volumes reported by CEDIGAZ. Statistical analysis of the database with accumulated 5 years of the Nightfire detections makes it possible to estimate instant flow rate for an individual flare, as well as integral flared volumes and long term trends for all the countries or oil and gas fields.

  15. Black carbon in the Arctic: the underestimated role of gas flaring and residential combustion emissions

    Directory of Open Access Journals (Sweden)

    A. Stohl

    2013-09-01

    annual mean Arctic BC surface concentrations due to residential combustion by 68% when using daily emissions. A large part (93% of this systematic increase can be captured also when using monthly emissions; the increase is compensated by a decreased BC burden at lower latitudes. In a comparison with BC measurements at six Arctic stations, we find that using daily-varying residential combustion emissions and introducing gas flaring emissions leads to large improvements of the simulated Arctic BC, both in terms of mean concentration levels and simulated seasonality. Case studies based on BC and carbon monoxide (CO measurements from the Zeppelin observatory appear to confirm flaring as an important BC source that can produce pollution plumes in the Arctic with a high BC / CO enhancement ratio, as expected for this source type. BC measurements taken during a research ship cruise in the White, Barents and Kara seas north of the region with strong flaring emissions reveal very high concentrations of the order of 200–400 ng m−3. The model underestimates these concentrations substantially, which indicates that the flaring emissions (and probably also other emissions in northern Siberia are rather under- than overestimated in our emission data set. Our results suggest that it may not be "vertical transport that is too strong or scavenging rates that are too low" and "opposite biases in these processes" in the Arctic and elsewhere in current aerosol models, as suggested in a recent review article (Bond et al., Bounding the role of black carbon in the climate system: a scientific assessment, J. Geophys. Res., 2013, but missing emission sources and lacking time resolution of the emission data that are causing opposite model biases in simulated BC concentrations in the Arctic and in the mid-latitudes.

  16. Black carbon in the Arctic: the underestimated role of gas flaring and residential combustion emissions

    Science.gov (United States)

    Stohl, A.; Klimont, Z.; Eckhardt, S.; Kupiainen, K.; Shevchenko, V. P.; Kopeikin, V. M.; Novigatsky, A. N.

    2013-09-01

    BC surface concentrations due to residential combustion by 68% when using daily emissions. A large part (93%) of this systematic increase can be captured also when using monthly emissions; the increase is compensated by a decreased BC burden at lower latitudes. In a comparison with BC measurements at six Arctic stations, we find that using daily-varying residential combustion emissions and introducing gas flaring emissions leads to large improvements of the simulated Arctic BC, both in terms of mean concentration levels and simulated seasonality. Case studies based on BC and carbon monoxide (CO) measurements from the Zeppelin observatory appear to confirm flaring as an important BC source that can produce pollution plumes in the Arctic with a high BC / CO enhancement ratio, as expected for this source type. BC measurements taken during a research ship cruise in the White, Barents and Kara seas north of the region with strong flaring emissions reveal very high concentrations of the order of 200-400 ng m-3. The model underestimates these concentrations substantially, which indicates that the flaring emissions (and probably also other emissions in northern Siberia) are rather under- than overestimated in our emission data set. Our results suggest that it may not be "vertical transport that is too strong or scavenging rates that are too low" and "opposite biases in these processes" in the Arctic and elsewhere in current aerosol models, as suggested in a recent review article (Bond et al., Bounding the role of black carbon in the climate system: a scientific assessment, J. Geophys. Res., 2013), but missing emission sources and lacking time resolution of the emission data that are causing opposite model biases in simulated BC concentrations in the Arctic and in the mid-latitudes.

  17. The physical origin of optical flares following GRB 110205A and the nature of the outflow

    Institute of Scientific and Technical Information of China (English)

    Wei-Hong Gao

    2011-01-01

    The optical emission of GRB 110205A is distinguished by two flares.We examine two possible scenarios for the optical afterglow emission.In the first scenario,the first optical flare is the reverse shock emission of the main outflow and the second one is powered by the prolonged activity of the central engine.However,we find that it is rather hard to reasonably interpret the late (t > 0.1 d) afterglow data unless the GRB efficiency is very high (~ 0.95).In the second scenario,the first optical flare is the low energy prompt emission and the second one is the reverse shock of the initial outflow.Within this scenario we can interpret the late afterglow emission self-consistently.The reverse shock region may be weakly magnetized and the decline of the second optical flare may be dominated by the high latitude emission,for which strong polarization evolution accompanying the quick decline is possible,as suggested by Fan et al.in 2008.Time-resolved polarimetry by RINGO2-1ike polarimeters will direcdy test our prediction.

  18. Temporal evolution of multiple evaporating ribbon sources in a solar flare

    CERN Document Server

    Graham, D R

    2015-01-01

    We present new results from the Interface Region Imaging Spectrograph showing the dynamic evolution of chromospheric evaporation and condensation in a flare ribbon, with the highest temporal and spatial resolution to date. IRIS observed the entire impulsive phase of the X-class flare SOL2014-09-10T17:45 using a 9.4 second cadence `sit-and-stare' mode. As the ribbon brightened successively at new positions along the slit, a unique impulsive phase evolution was observed for many tens of individual pixels in both coronal and chromospheric lines. Each activation of a new footpoint displays the same initial coronal up-flows of up to ~300 km/s, and chromospheric downflows up to 40 km/s. Although the coronal flows can be delayed by over 1 minute with respect to those in the chromosphere, the temporal evolution of flows is strikingly similar between all pixels, and consistent with predictions from hydrodynamic flare models. Given the large sample of independent footpoints, we conclude that each flaring pixel can be c...

  19. A Circular-ribbon Solar Flare Following an Asymmetric Filament Eruption

    CERN Document Server

    Liu, Chang; Liu, Rui; Lee, Jeongwoo; Pariat, Etienne; Wiegelmann, Thomas; Liu, Yang; Kleint, Lucia; Wang, Haimin

    2015-01-01

    The dynamic properties of flare ribbons and the often associated filament eruptions can provide crucial information on the flaring coronal magnetic field. This Letter analyzes the GOES-class X1.0 flare on 2014 March 29 (SOL2014-03-29T17:48), in which we found an asymmetric eruption of a sigmoidal filament and an ensuing circular flare ribbon. Initially both EUV images and a preflare nonlinear force-free field model show that the filament is embedded in magnetic fields with a fan-spine-like structure. In the first phase, which is defined by a weak but still increasing X-ray emission, the western portion of the sigmoidal filament arches upward and then remains quasi-static for about five minutes. The western fan-like and the outer spine-like fields display an ascending motion, and several associated ribbons begin to brighten. Also found is a bright EUV flow that streams down along the eastern fan-like field. In the second phase that includes the main peak of hard X-ray (HXR) emission, the filament erupts, leavi...

  20. A statistical study on the brightening propagation of post-flare loops

    Institute of Scientific and Technical Information of China (English)

    LI LePing; DUAN HongYu; ZHANG Jun

    2009-01-01

    After examining the data observed by TRACE 171 and 195 A from May 1998 to December 2006, we choose as our sample 190 (39 X-class and 151 M-class) flare events which display post-flare loops (PFLs). We investigate the brightening propagation of these PFLs of the events in the sample along the magnetic neutral lines. In most of the cases, the length of the flare ribbons (FRs) ranges from 20 to 170 Mm. The propagating duration of the brightening lasts 10-60 min. The velocities of the propagation associated with the flare strenght and the legth of the FRs,range from 5 to 35 km·s~(-1).Furthermore,a greater propagating velocity corresponds to a greater deceleration (or acceleration). These PFLs display three types of propagating patterns: (1) the brightening begins at the middle part of a set of PFLs, and propagates bi-directionally towards its both ends; (2) the brightening first appears at one end of a set of PFLs, and then propagates to the other; (3) the initial brightening takes place at two (or more than two) positions on two (or more than two) sets of PFLs, and each brightening propagates bi-directionally along the magnetic neutral line.

  1. A statistical study on the brightening propagation of post-flare loops

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    After examining the data observed by TRACE 171 and 195  from May 1998 to December 2006, we choose as our sample 190 (39 X-class and 151 M-class) flare events which display post-flare loops (PFLs). We investigate the brightening propagation of these PFLs of the events in the sample along the magnetic neutral lines. In most of the cases, the length of the flare ribbons (FRs) ranges from 20 to 170 Mm. The propagating duration of the brightening lasts 10-60 min. The velocities of the propagation associated with the flare strength and the length of the FRs, range from 5 to 35 km·s-1. Furthermore, a greater propagating velocity corresponds to a greater deceleration (or acceleration). These PFLs display three types of propagating patterns: (1) the brightening begins at the middle part of a set of PFLs, and propagates bi-directionally towards its both ends; (2) the brightening first appears at one end of a set of PFLs, and then propagates to the other; (3) the initial brightening takes place at two (or more than two) positions on two (or more than two) sets of PFLs, and each brightening propagates bi-directionally along the magnetic neutral line.

  2. Magnetic shear in flaring regions. I - Quantitative evaluation of the change in shear

    Science.gov (United States)

    Sivaraman, K. R.; Rausaria, R. R.; Aleem, S. M.

    1992-04-01

    The shear angle of the neutral line of the nonpotential magnetic field has been evaluated for one or two days prior to and after the flare event for 10 cases. The H-alpha filament positions were used to evaluate the shear in the neutral line. It is found that it is the change in the shear that occurs a day prior to the flare that can lead to the event. This change can be in either direction, i.e., it can be a large increase from a small value or a decrease from a large initial value. Thus it is the change in the shear angle that seems to be a deciding criterion for a flare to occur and not a large value for the shear angle itself. One instance is found where there was no significant change in the shear angle over a period of a few days and this region, although similar to other active regions studied, did not produce any flare activity.

  3. The comparison between two airborne LiDAR datasets to analyse debris flow initiation in north-western Iceland

    Science.gov (United States)

    Morino, Costanza; Conway, Susan J.; Balme, Matthew R.; Jordan, Colm; Hillier, John; Sæmundsson, Þorsteinn; Argles, Tom

    2015-04-01

    A debris flow is a very rapid to extremely rapid flow (e.g., 0.8-28 ms-1) [1], that occurs when coarse and poorly-sorted debris, mixed with water and/or air, move down hill slopes in response to gravity [2]. Both the fluid and the solid have a strong influence on the movement of debris flows. They can be extremely destructive, due to their capability of transporting metre-size boulders [e.g., 3, 4]. There are two main ways in which a debris flow can be initiated: by slope failure or by the "fire hose" effect. The slope failure type is particularly common in alpine regions, where landslides can evolve into debris flows [5], triggered by the coalescence of different slope failures. Steep slope gradients, high pore-water pressures, heavy rainfall and/or snowmelt favour this process. The "fire hose" effect occurs when there is a high concentration of debris accumulated within a pre-existing channel; a surge of water through the channel can then develop into a debris flow by incorporating this debris [e.g. 5-7]. In this study, we examine the triggering style of debris flows above the town of Ísafjörður in the Westfjords of Iceland. The slope above the town is characterised by a large topographic bench upon which 20-35 m of glacial till is perched. The sediments are unstable at the bench margin and thus generate frequent, large, hillslope debris flows [8, 9]. In our new analysis, we report on the comparison between the two airborne LiDAR elevation models (collected in 2007 and 2013 by the UK Natural Environment Research Council Airborne Research and Survey Facility), which display several new debris flows and also related mass movements. From these analyses, we find that debris flows in the region are triggered by simple failure of the glacial till, as recognised before [8, 9]. However, debris flows may also be regenerated by the "fire hose" effect, when debris that has collapsed into chutes is remobilised by a later snowmelt or precipitation event. Comparing

  4. MOST Observations of our Nearest Neighbor: Flares on Proxima Centauri

    CERN Document Server

    Davenport, James R A; Sasselov, Dimitar; Matthews, Jaymie M; Cameron, Chris

    2016-01-01

    We present a study of white light flares from the active M5.5 dwarf Proxima Centauri using the Canadian microsatellite MOST. Using 37.6 days of monitoring data from 2014 and 2015, we have detected 66 individual flare events, the largest number of white light flares observed to date on Proxima Cen. Flare energies in our sample range from $10^{29}$-$10^{31.5}$ erg, with complex, multi-peaked structure found in 22% of these events. The flare rate is lower than that of other classic flare stars of similar spectral type, such as UV Ceti, which may indicate Proxima Cen had a higher flare rate in its youth. Proxima Cen does have an unusually high flare rate given the slow reported rotation period, however. Extending the observed power-law occurrence distribution down to $10^{28}$ erg, we show that flares with flux amplitudes of 0.5% occur 63 times per day, while superflares with energies of $10^{33}$ erg occur ~8 times per year. Small flares may therefore pose a great difficulty in searches for transits from the rec...

  5. Enhancement in electron and ion temperatures due to solar flares as measured by SROSS-C2 satellite

    Directory of Open Access Journals (Sweden)

    D. K. Sharma

    2004-06-01

    Full Text Available The observations on the ionospheric electron and ion temperatures (Te and Ti measured by the RPA payload aboard the SROSS-C2 satellite have been used to study the effect of solar flares on ionospheric heating. The data on solar flare has been obtained from the National Geophysical Data Center (NGDC Boulder, Colorado (USA. It has been found that the electron and ion temperatures have a consistent enhancement during the solar flares on the dayside Earth's ionosphere. The estimated enhancement for the average electron temperature is from 1.3 to 1.9 times whereas for ion temperature it is from 1.2 to 1.4 times to the normal days average temperature. The enhancement of ionospheric temperatures due to solar flares is correlated with the diurnal variation of normal days' ionospheric temperatures. The solar flare does not have any significant effect on the nightside ionosphere. A comparison with the temperature obtained from the IRI-95 model also shows a similar enhancement.

  6. Slipping magnetic reconnections with multiple flare ribbons during an X-class solar flare

    CERN Document Server

    Zheng, Ruisheng; Wang, Bing

    2016-01-01

    With the observations of the Solar Dynamics Observatory, we present the slipping magnetic reconnections with multiple flare ribbons (FRs) during an X1.2 eruptive flare on 2014 January 7. A center negative polarity was surrounded by several positive ones, and there appeared three FRs. The three FRs showed apparent slipping motions, and hook structures formed at their ends. Due to the moving footpoints of the erupting structures, one tight semi-circular hook disappeared after the slippage along its inner and outer edge, and coronal dimmings formed within the hook. The east hook also faded as a result of the magnetic reconnection between the arcades of a remote filament and a hot loop that was impulsively heated by the under flare loops. Our results are accordant with the slipping magnetic reconnection regime in 3D standard model for eruptive flares. We suggest that complex structures of the flare is likely a consequence of the more complex flux distribution in the photosphere, and the eruption involves at least...

  7. Temporal evolution and spatial distribution of white-light flare kernels in a solar flare

    CERN Document Server

    Kawate, Tomoko; Nakatani, Yoshikazu; Ichimoto, Kiyoshi; Asai, Ayumi; Morita, Satoshi; Masuda, Satoshi

    2016-01-01

    On 2011 September 6, we observed an X2.1-class flare in continuum and H$\\alpha$ with a frame rate of about 30~Hz. After processing images of the event by using a speckle-masking image reconstruction, we identified white-light (WL) flare ribbons on opposite sides of the magnetic neutral line. We derive the lightcurve decay times of the WL flare kernels at each resolution element by assuming that the kernels consist of one or two components that decay exponentially, starting from the peak time. As a result, 42% of the pixels have two decay-time components with average decay times of 15.6 and 587 s, whereas the average decay time is 254 s for WL kernels with only one decay-time component. The peak intensities of the shorter decay-time component exhibit good spatial correlation with the WL intensity, whereas the peak intensities of the long decay-time components tend to be larger in the early phase of the flare at the inner part of the flare ribbons, close to the magnetic neutral line. The average intensity of th...

  8. The Power-Law Distribution of Flare Kernels and Fractal Current Sheets in a Solar Flare

    CERN Document Server

    Nishizuka, N; Takasaki, H; Kurokawa, H; Shibata, K; 10.1088/0004-637X/694/1/L74

    2013-01-01

    We report a detailed examination of the fine structure inside flare ribbons and the temporal evolution of this fine structure during the X2.5 solar flare that occurred on 2004 November 10. We examine elementary bursts of the C IV (1550{\\AA}) emission lines seen as local transient brightenings inside the flare ribbons in the ultraviolet (1600{\\AA}) images taken with Transition Region and Coronal Explorer, and we call them C IV kernels. This flare was also observed in Ha with the Sartorius 18 cm Refractor telescope at Kwasan observatory, Kyoto University, and in hard X-rays (HXR) with Reuven Ramaty High Energy Solar Spectroscopic Imager. Many C IV kernels, whose sizes were comparable to or less than 2", were found to brighten successively during the evolution of the flare ribbon. The majority of them were well correlated with the Ha kernels in both space and time, while some of them were associated with the HXR emission. These kernels were thought to be caused by the precipitation of nonthermal particles at the...

  9. Ensemble Forecasting of Major Solar Flares

    CERN Document Server

    Guerra, J A; Uritsky, V M

    2015-01-01

    We present the results from the first ensemble prediction model for major solar flares (M and X classes). Using the probabilistic forecasts from three models hosted at the Community Coordinated Modeling Center (NASA-GSFC) and the NOAA forecasts, we developed an ensemble forecast by linearly combining the flaring probabilities from all four methods. Performance-based combination weights were calculated using a Monte Carlo-type algorithm by applying a decision threshold $P_{th}$ to the combined probabilities and maximizing the Heidke Skill Score (HSS). Using the probabilities and events time series from 13 recent solar active regions (2012 - 2014), we found that a linear combination of probabilities can improve both probabilistic and categorical forecasts. Combination weights vary with the applied threshold and none of the tested individual forecasting models seem to provide more accurate predictions than the others for all values of $P_{th}$. According to the maximum values of HSS, a performance-based weights ...

  10. Gravitational fragmentation of the Carina Flare supershell

    Science.gov (United States)

    Wünsch, Richard

    2015-03-01

    We study the gravitational fragmentation of a thick shell comparing the analytical theory to 3D hydrodynamic simulations and to observations of the Carina Flare supershell. We use both grid-based (AMR) and particle-based (SPH) codes to follow the idealised model of the fragmenting shell and found an excellent agreement between the two codes. Growth rates of fragments at different wavelength are well described by the pressure assisted gravitational instability (PAGI) - a new theory of the thick shell fragmentation. Using the APEX telescope we observe a part of the surface of the Carina Flare supershell (GSH287+04-17) in the 13CO(2-1) line. We apply a new clump-finding algorithm DENDROFIND to identify 50 clumps. We determine the clump mass function and we construct the minimum spanning tree connecting clumps positions to estimate the typical distance among clumps. We conclude that the observed masses and distances correspond well to the prediction of PAGI.

  11. Heavy Ion Acceleration in Impulsive Solar Flares

    Institute of Scientific and Technical Information of China (English)

    王德焴

    2002-01-01

    The abundance enhancements of heavy ions Ne, Mg, Si and Fe in impulsive solar energetic particle (SEP) eventsare explained by a plasma acceleration mechanism. In consideration of the fact that the coronal plasma is mainlycomposed of hydrogen and helium ions, we think that theion-ion hybrid wave and quasi-perpendicular wave can.be excited by the energetic electron beam in impulsive solar flares. These waves may resonantly be absorbed byheavy ions when the frequencies of these waves are close to the second-harmonic gyrofrequencies of these heavyions. This requires the coronal plasma temperature to be located in the range ofT ~ (5 - 9) × 106 K in impulsivesolar flares and makes the average ionic charge state of these heavy ions in impulsive SEP events higher than theaverage ionic charge state of these heavy ions in gradual SEP events. These pre-heated and enhanced heavy ionsin impulsive SEP events.

  12. High energy flare physics group summary

    Science.gov (United States)

    Ryan, J. M.; Kurfess, J. D.

    1989-01-01

    The contributions of the High Energy Flare Physics Special Session in the American Astronomical Society Solar Physics Division Meeting are reviewed. Oral and poster papers were presented on observatories and instruments available for the upcoming solar maximum. Among these are the space-based Gamma Ray Observatory, the Solar Flare and Cosmic Burst Gamma Ray Experiment on the Ulysses spacecraft, the Soft X Ray Telescope on the spacecraft Solar-A, and the balloon-based Gamma Ray Imaging Device. Ground based observatories with new capabilities include the BIMA mm-wave interferometer (Univ. of California, Berkeley; Univ. of Illinois; Univ. of Maryland), Owens Valley Radio Observatory and the Very Large Array. The highlights of the various instrument performances are reported and potential data correlations and collaborations are suggested.

  13. Millimeter Observation of Solar Flares with Polarization

    Science.gov (United States)

    Silva, D. F.; Valio, A. B. M.

    2016-04-01

    We present the investigation of two solar flares on February 17 and May 13, 2013, studied in radio from 5 to 405 GHz (RSTN, POEMAS, SST), and in X-rays up to 300 keV (FERMI and RHESSI). The objective of this work is to study the evolution and energy distribution of the population of accelerated electrons and the magnetic field configuration. For this we constructed and fit the radio spectrum by a gyro synchrotron model. The optically thin spectral indices from radio observations were compared to that of the hard X-rays, showing that the radio spectral index is harder than the latter by 2. These flares also presented 10-15 % circular polarized emission at 45 and 90 GHz that suggests that the sources are located at different legs of an asymmetric loop.

  14. Search for neutrinos from flaring blazars

    Energy Technology Data Exchange (ETDEWEB)

    Kreter, Michael [Lehrstuhl fuer Astronomie, Universitaet Wuerzburg, Emil-Fischer-Strasse 31, 97074 Wuerzburg (Germany); ECAP, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Eberl, Thomas; James, Clancy [ECAP, Universitaet Erlangen-Nuernberg, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Kadler, Matthias [Lehrstuhl fuer Astronomie, Universitaet Wuerzburg, Emil-Fischer-Strasse 31, 97074 Wuerzburg (Germany); Collaboration: ANTARES-KM3NeT-Erlangen-Collaboration

    2016-07-01

    Jets from Active Galactic Nuclei (AGN) are among the best candidates for the recently detected extraterrestrial neutrino flux. Hadronic AGN jet-emission models predict a tight correlation between the neutrino flux and the time-variable gamma-ray emission. At the same time, the atmospheric-background (noise) signal, which often dominates in neutrino-astronomical observations, can be substantially reduced by rejecting long-lasting periods of low flux. For these reasons, short high-amplitude gamma-ray flares, as often observed in blazars, can be used to substantially increase the sensitivity of neutrino telescopes in point-source searches. We develop a strategy to search for TeV neutrinos from flaring blazar jets from the TANAMI sample using the ANTARES telescope and Fermi gamma-ray light curves. An unbinned maximum-likelihood method is applied to optimize the probability of a neutrino detection from TANAMI sources.

  15. Nonlocal thermal transport in solar flares

    Science.gov (United States)

    Karpen, Judith T.; Devore, C. Richard

    1987-01-01

    A flaring solar atmosphere is modeled assuming classical thermal transport, locally limited thermal transport, and nonlocal thermal transport. The classical, local, and nonlocal expressions for the heat flux yield significantly different temperature, density, and velocity profiles throughout the rise phase of the flare. Evaporation of chromospheric material begins earlier in the nonlocal case than in the classical or local calculations, but reaches much lower upward velocities. Much higher coronal temperatures are achieved in the nonlocal calculations owing to the combined effects of delocalization and flux limiting. The peak velocity and momentum are roughly the same in all three cases. A more impulsive energy release influences the evolution of the nonlocal model more than the classical and locally limited cases.

  16. Selective Acceleration in Impulsive Solar Flares

    Institute of Scientific and Technical Information of China (English)

    王德焴

    2001-01-01

    A plasma acceleration mechanism is proposed to explain the dramatic enhancement in the ratio of 3 He/4He, (enhancement factor 102 - 103) observed in solar 3He-rich flares. Considering that coronal plasma is mainly composed of hydrogen and helium ions, the hydrogen ion-helium ion hybrid waves and quasi-perpendicular waves can be excited by energetic electron beam during the impulsive solarflares. The frequencies of these waves are close to the 3He++ ion gyrofrequency, but far from the 4He++ ion gyrofrequency. Most of these waves are selectively absorbed by 3He ions. These preheated 3He ions can be successively stochastic accelerated by Alfvén turbulence, when their velocities are larger than the local Alfvén velocity. It makes the ratio of 3He/4He dramatically enhanced and the acceleration energy spectrum of 3He ions forms a power-law distribution during the impulsive solar flares.

  17. Monitoring and modeling radio flares from microquasars

    CERN Document Server

    Trushkin, S A; Bursov, N N

    2000-01-01

    We present results of long-term daily monitoring of a sample of Galactic radio-emitting X-ray binaries showing relativistic jets (RJXRB): SS433, Cyg X-3, and GRS 1915+105, with the RATAN-600 radio telescope in the 0.6-22 GHz range. We carried out the modeling calculations to understand the temporal (1--100 days) and spectral (1-22 GHz) dependence. We tested the finite jet segment models and we found that the geometry of the conical hollow jets is responsible for either a power law or an exponential decay of the flares. SS433 was monitored for 100 days in 1997 and 120 days in 1999. From the quiescent radio light curves, we obtained clear evidence of a 6.04-day 10-15% modulation. Three powerful flares (up to 13 Jy) from Cyg X-3 were detected in April 2000.

  18. Cyclical Variability of Prominences, CMEs and Flares

    Indian Academy of Sciences (India)

    J. L. Ballester

    2000-09-01

    Solar flares, prominences and CMEs are well known manifestations of solar activity. For many years, qualitative studies were made about the cyclical behaviour of such phenomena. Nowadays, more quantitative studies have been undertaken with the aim to understand the solar cycle dependence of such phenomena as well as peculiar behaviour, such as asymmetries and periodicities, occurring within the solar cycle. Here, we plan to review the more recent research concerning all these topics.

  19. Protection of Communication System From Solar Flares

    OpenAIRE

    Karthik, K.(Department of Physics, New York University, New York, NY, United States of America); Shirvram, B.

    2008-01-01

    Solar flares are enormous explosions on the surface of the sun and they release energy of the order of billion megatons of TNThis energy is in the form of electromagnetic radiations such as alpha, gamma, and ultraviolet rays. When exposed to high doses of radiation like 2-15 kilorad (Si), silicon integrated circuits in satellite communication systems fail to operate properly, thus affecting the performance of communication systems. Therefore, the major issue that needs to be addressed is the ...

  20. Universality in solar flare and earthquake occurrence

    OpenAIRE

    de Arcangelis, L.; Godano, C.; Lippiello, E.; Nicodemi, M.

    2006-01-01

    Earthquakes and solar flares are phenomena involving huge and rapid releases of energy characterized by complex temporal occurrence. By analysing available experimental catalogs, we show that the stochastic processes underlying these apparently different phenomena have universal properties. Namely both problems exhibit the same distributions of sizes, inter-occurrence times and the same temporal clustering: we find afterflare sequences with power law temporal correlations as the Omori law for...

  1. The Discriminant Analysis Flare Forecasting System (DAFFS)

    Science.gov (United States)

    Leka, K. D.; Barnes, Graham; Wagner, Eric; Hill, Frank; Marble, Andrew R.

    2016-05-01

    The Discriminant Analysis Flare Forecasting System (DAFFS) has been developed under NOAA/Small Business Innovative Research funds to quantitatively improve upon the NOAA/SWPC flare prediction. In the Phase-I of this project, it was demonstrated that DAFFS could indeed improve by the requested 25% most of the standard flare prediction data products from NOAA/SWPC. In the Phase-II of this project, a prototype has been developed and is presently running autonomously at NWRA.DAFFS uses near-real-time data from NOAA/GOES, SDO/HMI, and the NSO/GONG network to issue both region- and full-disk forecasts of solar flares, based on multi-variable non-parametric Discriminant Analysis. Presently, DAFFS provides forecasts which match those provided by NOAA/SWPC in terms of thresholds and validity periods (including 1-, 2-, and 3- day forecasts), although issued twice daily. Of particular note regarding DAFFS capabilities are the redundant system design, automatically-generated validation statistics and the large range of customizable options available. As part of this poster, a description of the data used, algorithm, performance and customizable options will be presented, as well as a demonstration of the DAFFS prototype.DAFFS development at NWRA is supported by NOAA/SBIR contracts WC-133R-13-CN-0079 and WC-133R-14-CN-0103, with additional support from NASA contract NNH12CG10C, plus acknowledgment to the SDO/HMI and NSO/GONG facilities and NOAA/SWPC personnel for data products, support, and feedback. DAFFS is presently ready for Phase-III development.

  2. Lupus flares in two established end-stage renal disease patients with on-line hemodiafiltration during pregnancy - case series.

    Science.gov (United States)

    Althaf, M M; Abdelsalam, M S; Alfurayh, O I

    2014-08-01

    Many patients with established end-stage renal disease on maintenance dialysis as a result of lupus nephritis are young females in their reproductive years. We report two such patients dialyzed with on-line hemodiafiltration who developed reactivation of lupus disease activity only when they conceived after initial systemic lupus erythematosus burnout. We believe that the flare was triggered by both efficient dialysis and hormonal changes during pregnancy. The flares were treated with oral corticosteroids with an excellent response. Both patients had live births but delivered preterm.

  3. Incidence and Predictive Factors of Pain Flare After Spine Stereotactic Body Radiation Therapy: Secondary Analysis of Phase 1/2 Trials

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Hubert Y.; Allen, Pamela K. [Department of Radiation Oncology, University of Texas MD Anderson Cancer, Houston, Texas (United States); Wang, Xin S. [Department of Symptom Research, University of Texas MD Anderson Cancer, Houston, Texas (United States); Chang, Eric L. [Department of Radiation Oncology, University of Texas MD Anderson Cancer, Houston, Texas (United States); Department of Radiation Oncology, USC Norris Cancer Center, Los Angeles, California (United States); Rhines, Laurence D.; Tatsui, Claudio E. [Department of Neurosurgery, University of Texas MD Anderson Cancer, Houston, Texas (United States); Amini, Behrang [Department of Diagnostic Radiology, University of Texas MD Anderson Cancer, Houston, Texas (United States); Wang, Xin A. [Department of Radiation Physics, University of Texas MD Anderson Cancer, Houston, Texas (United States); Tannir, Nizar M. [Department of Genitourinary Medical Oncology, University of Texas MD Anderson Cancer, Houston, Texas (United States); Brown, Paul D. [Department of Radiation Oncology, University of Texas MD Anderson Cancer, Houston, Texas (United States); Ghia, Amol J., E-mail: AJGhia@mdanderson.org [Department of Radiation Oncology, University of Texas MD Anderson Cancer, Houston, Texas (United States)

    2014-11-15

    Purpose/Objective(s): To perform a secondary analysis of institutional prospective spine stereotactic body radiation therapy (SBRT) trials to investigate posttreatment acute pain flare. Methods and Materials: Medical records for enrolled patients were reviewed. Study protocol included baseline and follow-up surveys with pain assessment by Brief Pain Inventory and documentation of pain medications. Patients were considered evaluable for pain flare if clinical note or follow-up survey was completed within 2 weeks of SBRT. Pain flare was defined as a clinical note indicating increased pain at the treated site or survey showing a 2-point increase in worst pain score, a 25% increase in analgesic intake, or the initiation of steroids. Binary logistic regression was used to determine predictive factors for pain flare occurrence. Results: Of the 210 enrolled patients, 195 (93%) were evaluable for pain flare, including 172 (88%) clinically, 135 (69%) by survey, and 112 (57%) by both methods. Of evaluable patients, 61 (31%) had undergone prior surgery, 57 (29%) had received prior radiation, and 34 (17%) took steroids during treatment, mostly for prior conditions. Pain flare was observed in 44 patients (23%). Median time to pain flare was 5 days (range, 0-20 days) after the start of treatment. On multivariate analysis, the only independent factor associated with pain flare was the number of treatment fractions (odds ratio = 0.66, P=.004). Age, sex, performance status, spine location, number of treated vertebrae, prior radiation, prior surgery, primary tumor histology, baseline pain score, and steroid use were not significant. Conclusions: Acute pain flare after spine SBRT is a relatively common event, for which patients should be counseled. Additional study is needed to determine whether prophylactic or symptomatic intervention is preferred.

  4. Fine structure of flare ribbons and evolution of electric currents

    CERN Document Server

    Sharykin, I N

    2014-01-01

    Emission of solar flares across the electromagnetic spectrum is often observed in the form of two expanding ribbons. The standard flare model explains the flare ribbons as footpoints of magnetic arcades, emitting due to interaction of energetic particles with the chromospheric plasma. However, the physics of this interaction and properties of the accelerated particles are still unknown. We present results of multiwavelength observations of C2.1 flare of August 15, 2013, observed with New Solar Telescope (NST) of Big Bear Solar Observatory, Solar Dynamics Observatory (SDO), GOES and FERMI spacecraft. The observations reveal previously unresolved sub-arcsecond structure of the flare ribbons in regions of strong magnetic field consisting from numerous small-scale bright knots. We observe red-blue asymmetry of H alpha flare ribbons with a width as small as 100 km. We discuss the relationship between the ribbons and vertical electric currents estimated from vector magnetograms, and show that Joule heating can be r...

  5. Investigation of the Relationship between Solar Flares and Sunspot Groups

    Science.gov (United States)

    Eren, S.; Kilcik, A.

    2017-01-01

    We studied the relationship between X-Ray flare numbers (C, M, and, X class flares) and sunspot counts in four categories (Simple (A + B), Medium (C), Large (D + E + F), and End (H)). All data sets cover the whole Solar Cycle 23 and the ascending and maximum phases of Cycle 24 (1996-2014). Pearson correlation analysis method was used to investigate the degree of relationship between monthly solar flare numbers and sunspot counts observed in different sunspot categories. We found that the C, M, and X class flares have highest correlation with the large group sunspot counts, while the small category does not any meaningful correlation. Obtained correlation coefficients between large groups and C, M, and X class flare numbers are 0.79, 0.74, and 0.4, respectively. Thus, we conclude that the main sources of X-Ray solar flares are the complex/large sunspot groups.

  6. CME-flare association during the 23rd solar cycle

    Science.gov (United States)

    Mahrous, A.; Shaltout, M.; Beheary, M. M.; Mawad, R.; Youssef, M.

    2009-04-01

    The relation between coronal mass ejections (CMEs) and solar flares are statistically studied. More than 10,000 CME events observed by SOHO/LASCO during the period 1996-2005 have been analyzed. The soft X-ray flux measurements provided by the Geostationary Operational Environmental Satellite (GOES), recorded more than 20,000 flares in the same time period. The data is filtered under certain temporal and spatial conditions to select the CME-flare associated events. The results show that CME-flare associated events are triggered with a lift-off time within the range 0.4-1.0 h. We list a set of 41 CME-flare associated events satisfying the temporal and spatial conditions. The listed events show a good correlation between the CME energy and the X-ray flux of the CME-flare associated events with correlation coefficient of 0.76.

  7. Bayesian timing analysis of giant flare of SGR 1806-20 by RXTE PCA

    CERN Document Server

    Hambaryan, V; Kokkotas, K D

    2010-01-01

    By detecting high frequency quasi-periodic oscillations (QPOs) and estimating frequencies of them during the decaying tail of giant flares from Soft Gamma-ray Repeaters (SGRs) useful constraints for the equation of state (EoS) of superdense matter may be obtained via comparison with theoretical predictions of eigenfrequencies. We used the data collected by the Rossi X-Ray Timing Explorer (RXTE/XTE) Proportional Counter Array (PCA) of a giant flare of SGR 1806-20 on 2004 Dec 27 and applied a Bayesian periodicity detection method (Gregory & Loredo, 1992) for the search of oscillations of transient nature. In addition to the already detected frequencies, we found a few new frequencies (f_{QPOs} ~ 16.9, 21.4, 36.4, 59.0, 116.3 Hz) of oscillations predicted by Colaiuda et al. (2009) based on the APR_{14} EoS (Akmal et al., 1998) for SGR 1806-20.

  8. A comparison of the kinetics of low-density lipoprotein oxidation initiated by copper or by azobis (2-amidinopropane).

    Science.gov (United States)

    Thomas, M J; Chen, Q; Franklin, C; Rudel, L L

    1997-01-01

    This article describes the kinetics of low density lipoprotein (LDL) oxidation catalyzed by azobis (2-amidinopropane) dihydrochloride, ABAP, or by copper. The LDLs were isolated from nonhuman primates fed diets enriched in one of three types of fatty acids: saturated fatty acids, monounsaturated fatty acids, predominantly, oleic acid, or polyunsaturated fatty acids, predominantly linoleic acid. Oxidation was followed by monitoring the formation of conjugated diene hydroperoxides from polyunsaturated fatty acids (PUFA). For both copper and ABAP-initiated oxidation, the rate of LDL oxidation depended on the concentrations of initiator, PUFA, and LDL. Except for the dependence on PUFA concentration the rate of LDL oxidation was not directly influenced by the fatty acid composition of the LDL particle. The two initiators had very different dependence on initiator concentration. Because LDL particles are essentially small, lipid-rich droplets, the kinetic descriptions of LDL oxidation assumed: (1), that there was only one chain per particle, and (2) that the radical chain was terminated when a second radical either entered or was formed in the particle. When two LDL samples having very different lag times were mixed, the oxidation profile was bimodal. This finding demonstrated that the oxidation of native LDL particles was independent of the oxidation state of the other native LDL particles in solution, i.e., LDL particles do not rapidly exchange radicals, for example, hydroperoxyl radicals. Oxidation initiated by ABAP was proportional to [ABAP]0.5, suggesting that hydroperoxyl radical recombination between the lipid hydroperoxyl radical and the ABAP-hydroperoxyl radical was the chain-terminating step. The reciprocal of the rate of copper oxidation was linearly related to the reciprocal copper concentration, demonstrating that the binding of copper to LDL was necessary to initiate oxidation. This binding constant showed considerable variability among LDL samples. The

  9. X-ray Emission Characteristics of Flares Associated with CMEs

    Indian Academy of Sciences (India)

    Malini Aggarwal; Rajmal Jain; A. P. Mishra; P. G. Kulkarni; Chintan Vyas; R. Sharma; Meera Gupta

    2008-03-01

    We present the study of 20 solar flares observed by ``Solar X-ray Spectrometer (SOXS)” mission during November 2003 to December 2006 and found associated with coronal mass ejections (CMEs) seen by LASCO/SOHO mission. In this investigation, X-ray emission characteristics of solar flares and their relationship with the dynamics of CMEs have been presented.We found that the fast moving CMEs, i.e., positive acceleration are better associated with short rise time (< 150 s) flares. However, the velocity of CMEs increases as a function of duration of the flares in both 4.1–10 and 10–20 keV bands. This indicates that the possibility of association of CMEs with larger speeds exists with long duration flare events. We observed that CMEs decelerate with increasing rise time, decay time and duration of the associated X-ray flares. A total 10 out of 20 CMEs under current investigation showed positive acceleration, and 5 of them whose speed did not exceed 589 km/s were associated with short rise time (< 150 s) and short duration (< 1300 s) flares. The other 5 CMEs were associated with long duration or large rise time flare events. The unusual feature of all these positive accelerating CMEs was their low linear speed ranging between 176 and 775 km/s. We do not find any significant correlation between X-ray peak intensity of the flares with linear speed as well as acceleration of the associated CMEs. Based on the onset time of flares and associated CMEs within the observing cadence of CMEs by LASCO, we found that in 16 cases CME preceded the flare by 23 to 1786 s, while in 4 cases flare occurred before the CME by 47 to 685 s. We argue that both events are closely associated with each other and are integral parts of one energy release system.

  10. Observing the formation of flare-driven coronal rain

    OpenAIRE

    Scullion, E.; Rouppe van der Voort, L.; Antolin, P.; Wedemeyer, S.; Vissers, G.; E. P. Kontar; Gallagher, P

    2016-01-01

    PA. GV are funded by the European Research Council under the European Union Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement nr. 291058 Flare-driven coronal rain can manifest from rapidly cooled plasma condensations near coronal loop-tops in thermally unstable post-flare arcades. We detect 5 phases that characterise the post-flare decay:heating, evaporation, conductive cooling dominance for ~120 s, radiative/ enthalpy cooling dominance for ~4700 s and finally catastrophic ...

  11. H$\\mathbf{\\alpha}$ Intensity Oscillations in Large Flares

    Indian Academy of Sciences (India)

    Ram Ajor Maurya; Ashok Ambastha

    2008-03-01

    We reinvestigate the problem of Hα intensity oscillations in large flares, particularly those classified as X-class flares. We have used high spatial and temporal resolution digital observations obtained from Udaipur Solar Observatory during the period 1998–2006 and selected several events. Normalized Lomb–Scargle periodogram method for spectral analysis was used to study the oscillatory power in quiet and active chromospheric locations, including the flare ribbons.

  12. The Study of Flare Stars in Byurakan Observatory

    Science.gov (United States)

    Melikian, N. D.

    2016-09-01

    A brief description of the observations and the study of flare stars in Byurakan observatory is presented. In particular it is shown that there is a real dependence between flare activity and the distance between components of UV Ceti. The spectral study of a flare on WX Uma indicated on strong influence of the continuous emission, which is operated from 6000Å and rapidly growing to the short wavelength.

  13. Gas flaring from a rural landowner's perspective

    Energy Technology Data Exchange (ETDEWEB)

    Vasseur, P. [Farmers' Advocate of Alberta, Three Hills, AB (Canada)

    2000-07-01

    The public perception of flaring by the petroleum and natural gas industry was discussed. Flaring has never been embraced by the rural community in Alberta. Flaring is seen as an infringement on health and a contributing source of air pollution. While several studies have been undertaken to determine the effects of flaring, it seems that any conclusive information has not been made available to the public. The author suggested that some rural residents suspect that only favourable information is released or that it has been influenced by the energy sector. They also firmly believe that an increase in animal and health concerns is directly associated with emissions from flaring. Studies have identified about 250 different compounds in flare emissions, including volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and other toxic and carcinogenic compounds such as toluene, benzene, and xylene. Some rural residents are sceptical that scientists know the full extent of the effects from the 250 compounds produced by flaring. Also, since emissions from all flares are not the same, this would require an individual study for each flare for a thorough analysis. Studies have also shown that some flares have a combustion efficiency of only 64 per cent. Other studies do not support complaints that health problems stem from nearby wells. Other major perceptions are that flaring adds to the greenhouse effect, it contributes to climatic change and damages soils and vegetation. The author emphasized that the energy sector has to make an effort to reduce the number of flares and most importantly communicate with the rural community more effectively.

  14. Spots and White Light Flares in an L Dwarf

    Science.gov (United States)

    2013-01-01

    Program GN-2012A-Q-37) GMOS spectrograph (Hook et al. 2004) when a series of flares occurred. A spectrum of the most powerful flare in its impulsive...10:14 Hα HeI HeI HeI OI Fig. 4. Gemini-North GMOS spectra of W1906+40 in quiescence (below) and in flare. Note the broad Hα, atomic emission lines

  15. Flare-induced signals in polarization measurements during the X2.6 flare on 2005 January 15

    Science.gov (United States)

    Zhao, Meng; Wang, Jing-Xiu; Matthews, Sarah; Ming-DeDing; Zhao, Hui; Jin, Chun-Lan

    2009-07-01

    Flare-induced signals in polarization measurements which were manifested as apparent polarity reversal in magnetograms have been reported since 1981. We are motivated to further quantify the phenomenon by asking two questions: can we distinguish the flare-induced signals from real magnetic changes during flares, and what we can learn about flare energy release from the flare-induced signals? We select the X2.6 flare that occurred on 2005 January 15, for further study. The flare took place in NOAA active region (AR) 10720 at approximately the central meridian, which makes the interpretation of the vector magnetograms less ambiguous. We have identified that flare-induced signals during this flare appeared in six zones. The zones are located within an average distance of 5 Mm from their weight center to the main magnetic neutral line, have an average size of (0.6±0.4)×1017 cm2, duration of 13±4 min, and flux density change of 181±125 G in the area of reversed polarity. The following new facts have been revealed by this study: (1) the flare-induced signal is also seen in the transverse magnetograms but with smaller magnitude, e.g., about 50 G; (2) the flare-induced signal mainly manifests itself as apparent polarity reversal, but the signal starts and ends as a weakening of flux density; (3) The flare-induced signals appear in phase with the peaks of hard X-ray emission as observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), and mostly trace the position of RHESSI hard X-ray footpoint sources. (4) in four zones, it takes place co-temporally with real magnetic changes which persist after the flare. Only for the other two zones does the flux density recover to the pre-flare level immediately after the flare. The physical implications of the flare-induced signal are discussed in view of its relevance to the non-thermal electron precipitation and primary energy release in the flare.

  16. Flare-induced signals in polarization measurements during the X2.6 flare on 2005 January 15

    Institute of Scientific and Technical Information of China (English)

    Meng Zhao; Jing-Xiu Wang; Sarah Matthews; Ming-De Ding; Hui Zhao; Chun-Lan Jin

    2009-01-01

    Flare-induced signals in polarization measurements which were manifested as apparent polarity reversal in magnetograms have been reported since 1981. We are motivated to further quantify the phenomenon by asking two questions: can we distinguish the flare-induced signals from real magnetic changes during flares, and what we can learn about flare energy release from the flare-induced signals? We select the X2.6 flare that occurred on 2005 January 15, for further study. The flare took place in NOAA active re-gion (AR) 10720 at approximately the central meridian, which makes the interpretation of the vector magnetograms less ambiguous. We have identified that flare-induced signals during this flare appeared in six zones. The zones are located within an average distance of 5 Mm from their weight center to the main magnetic neutral line, have an average size of (0.6±0.4)×1017 cm2, duration of 13±4 min, and flux density change of 181±125 G in the area of reversed polarity. The following new facts have been revealed by this study: (1) the flare-induced signal is also seen in the transverse magnetograms but with smaller magnitude, e.g., about 50 G; (2) the flare-induced signal mainly manifests itself as apparent polarity reversal, but the signal starts and ends as a weakening of flux density; (3) The flare-induced signals appear in phase with the peaks of hard X-ray emission as observed by the Ramaty High Energy Solar Spectroscopic lmager (RHESSI), and mostly trace the position of RHESSI hard X-ray footpoint sources. (4) in four zones, it takes place cotemporally with real magnetic changes which persist after the flare. Only for the other two zones does the flux density recover to the pre-flare level immediately after the flare.The physical implications of the flare-induced signal are discussed in view of its relevance to the non-thermal electron precipitation and primary energy release in the flare.

  17. Recurring millimeter flares as evidence for star-star magnetic reconnection events in the DQ Tauri PMS binary system

    CERN Document Server

    Salter, D M; Getman, K V; Hogerheijde, M R; van Kempen, T A; Carpenter, J M; Blake, G A; Wilner, D

    2010-01-01

    Observations of the T Tauri spectroscopic binary DQ Tau in April 2008 captured an unusual flare at 3 mm, which peaked at an observed max flux of 0.5 Jy (about 27x the quiescent value). Here we present follow-up mm observations that demonstrate a periodicity to the phenomenon. While monitoring 3 new periastron encounters, we detect flares within 17.5 hrs (or 4.6%) of the orbital phase of the first reported flare, and we constrain the main emitting region to a stellar height of 3.7-6.8 Rstar. The recorded activity is consistent with the proposed picture for synchrotron emission initiated by a magnetic reconnection event when the two stellar magnetospheres of the highly eccentric (e=0.556) binary are believed to collide near periastron as the stars approach a minimum separation of 8 Rstar (~13 Rsolar). The similar light curve decay profiles allow us to estimate an average flare duration of 30 hrs. Assuming one mm flare per orbit, DQ Tau could spend approximately 8% of its 15.8-d orbital period in an elevated flu...

  18. Evidence of Solar Flare Triggering due to Loop-Loop Interaction Caused by Footpoint Shear-Motion

    CERN Document Server

    Kumar, Pankaj; Somov, B V; Manoharan, P K; Erdelyi, R; Uddin, Wahab

    2010-01-01

    We analyze multi-wavelength data of a M7.9/1N class solar flare which occurred on 27 April, 2006 from AR NOAA 10875. GOES soft X-ray images provide the most likely signature of two interacting loops and their reconnection, which triggers the solar flare. TRACE 195 A images also reveal the loop-loop interaction and the formation of `X' points with converging motion (~30 km/s) at the reconnection site in-between this interacting loop system. This provides the evidence of progressive reconnection and flare maximization at the interaction site in the active region. The absence of type III radio burst during this time period indicates no opening of magnetic field lines during the flare energy release, which implies only the change of field lines connectivity/orientation during the loop-loop interaction and reconnection process. The Ondrejov dynamic radio spectrum shows an intense decimetric (DCIM) radio burst (2.5--4.5 GHz, duration ~3 min) during flare initiation, which reveals the signature of particle accelerat...

  19. A Paired Comparison of Initial and Recurrent Concussions Sustained by US High School Athletes Within a Single Athletic Season.

    Science.gov (United States)

    Currie, Dustin W; Comstock, R Dawn; Fields, Sarah K; Cantu, Robert C

    To compare initial and recurrent concussions regarding average number of days between concussions, acute concussion symptoms and symptom resolution time, and return to play time. High school athletes sustaining multiple concussions linked within sport seasons drawn from a large sports injury surveillance study. Retrospective analysis of longitudinal surveillance data. Number of days between concussions, number of symptoms endorsed, specific symptoms endorsed, symptom resolution time, return to play time. Median time between initial and recurrent concussions was 21 days (interquartile range = 10-43 days). Loss of consciousness, the only significant symptom difference, occurred more frequently in recurrent (6.8%) than initial (1.7%) concussions (P = .04). No significant difference was found in the number of symptoms (P = .84) or symptom resolution time (P = .74). Recurrent concussions kept athletes from play longer than initial concussions (P concussions were season ending. We found that athletes' initial and recurrent concussions had similar symptom presentations and resolution time. Despite these similarities, athletes were restricted from returning to play for longer periods following a recurrent concussion, indicating clinicians are managing recurrent concussions more conservatively. It is probable that concussion recognition and management are superior now compared with when previous studies were published, possibly improving recurrent concussion outcomes.

  20. A characterization of solution gas flaring in Alberta.

    Science.gov (United States)

    Johnson, M R; Kostiuk, L W; Spangelo, J L

    2001-08-01

    Information reported here is the result of a detailed analysis of data on flared and vented solution gas in the Province of Alberta in 1999. A goal of characterizing these flares was to aid in the improved management of solution gas flaring. In total, 4499 oil and bitumen batteries reported flaring or venting with a combined gas volume of 1.42 billion m3. There was significant site-to-site variation in volumes of gas flared or vented, gas composition, and flare design. Approximately 5% of physical batteries generate 35.7% of the gas flared and vented from oil and bitumen batteries. Therefore, if one were to attempt to mitigate flaring, significant progress could be made by starting with only the largest sites. The monthly variability of gas volumes was considered because high variability could affect implementation of alternative technologies. It was found that slightly more than 40% of the sites were reasonably steady and had monthly deviations of 100% or less from the average flared volume. The variability in monthly volumes was less for the larger batteries. Data from individual well sites show significant variability in the relative concentrations of each of the major species contained in solution gas.

  1. A statistical study of post-flare-associated CME events

    Science.gov (United States)

    Youssef, M.; Mawad, R.; shaltout, Mosalam

    2013-04-01

    We present a statistical study of post-flare-associated CMEs (PFA-CMEs) during the period from 1996 to 2010. By investigating all CMEs and X-ray flares, respectively, in the LASCO and GOES archives, we found 15875 CMEs of which masses are well measured and 25112 X-ray flares of which positions are determined from their optical counterparts. Under certain temporal and spatial criteria of these CMEs and solar flare events, 291PFA-CMEs events have been selected. Linking the flare fluxes with CME speeds of these paired events, we found that there is a reasonable positive linear relation between the CME linear speed and associated flare flux. The results show also the CME width increases as the flux of its associated solar flare increases. Besides we found that there is a fine positive linear relation between the CME mass and its width. Matching the flare fluxes with CME masses of these paired events, we find the CME mass increases as the flux of its associated solar flare increases. Finally we find the PFA-CME events are in regular more decelerated than the other CMEs.

  2. Nuclear processes and neutrino production in solar flares

    Science.gov (United States)

    Lingenfelter, R. E.; Ramaty, R.; Murphy, R. J.; Kozlovsky, S.

    1985-01-01

    The determination of flare neutrino flux is approached from the standpoint of recent observations and theoretical results on the nuclear processes in solar flares. Attention is given to the energy spectra and total numbers of accelerated particles in flares, as well as their resulting production of beta(+)-emitting radionuclei and pions; these should be the primary sources of neutrinos. The observed 0.511 MeV line flux for the June 21, 1980 flare is compared with the expected from the number and spectrum of accelerated particles.

  3. Global Energetics of Solar Flares. V. Energy Closure in Flares and Coronal Mass Ejections

    Science.gov (United States)

    Aschwanden, Markus J.; Caspi, Amir; Cohen, Christina M. S.; Holman, Gordon; Jing, Ju; Kretzschmar, Matthieu; Kontar, Eduard P.; McTiernan, James M.; Mewaldt, Richard A.; O’Flannagain, Aidan; Richardson, Ian G.; Ryan, Daniel; Warren, Harry P.; Xu, Yan

    2017-02-01

    In this study we synthesize the results of four previous studies on the global energetics of solar flares and associated coronal mass ejections (CMEs), which include magnetic, thermal, nonthermal, and CME energies in 399 solar M- and X-class flare events observed during the first 3.5 yr of the Solar Dynamics Observatory (SDO) mission. Our findings are as follows. (1) The sum of the mean nonthermal energy of flare-accelerated particles ({E}{nt}), the energy of direct heating ({E}{dir}), and the energy in CMEs ({E}{CME}), which are the primary energy dissipation processes in a flare, is found to have a ratio of ({E}{nt}+{E}{dir}+{E}{CME})/{E}{mag}=0.87+/- 0.18, compared with the dissipated magnetic free energy {E}{mag}, which confirms energy closure within the measurement uncertainties and corroborates the magnetic origin of flares and CMEs. (2) The energy partition of the dissipated magnetic free energy is: 0.51 ± 0.17 in nonthermal energy of ≥slant 6 {keV} electrons, 0.17 ± 0.17 in nonthermal ≥slant 1 {MeV} ions, 0.07 ± 0.14 in CMEs, and 0.07 ± 0.17 in direct heating. (3) The thermal energy is almost always less than the nonthermal energy, which is consistent with the thick-target model. (4) The bolometric luminosity in white-light flares is comparable to the thermal energy in soft X-rays (SXR). (5) Solar energetic particle events carry a fraction ≈ 0.03 of the CME energy, which is consistent with CME-driven shock acceleration. (6) The warm-target model predicts a lower limit of the low-energy cutoff at {e}c≈ 6 {keV}, based on the mean peak temperature of the differential emission measure of T e = 8.6 MK during flares. This work represents the first statistical study that establishes energy closure in solar flare/CME events.

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

    Science.gov (United States)

    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.

  5. Comparisons of Stuttering Frequency during and after Speech Initiation in Unaltered Feedback, Altered Auditory Feedback and Choral Speech Conditions

    Science.gov (United States)

    Saltuklaroglu, Tim; Kalinowski, Joseph; Robbins, Mary; Crawcour, Stephen; Bowers, Andrew

    2009-01-01

    Background: Stuttering is prone to strike during speech initiation more so than at any other point in an utterance. The use of auditory feedback (AAF) has been found to produce robust decreases in the stuttering frequency by creating an electronic rendition of choral speech (i.e., speaking in unison). However, AAF requires users to self-initiate…

  6. Education for Sustainable Development in Ethnic Autonomous Areas of China: A Comparison of Two Curriculum Initiatives and Their Educational Implications

    Science.gov (United States)

    Khoo, Yishin

    2015-01-01

    This paper examines the educational implications of two curriculum initiatives in China that have produced curricular materials promoting education for sustainable development (ESD) in minority-populated ethnic autonomous areas in China. The two curriculum projects present distinctive discourses, conceptions, models, frameworks and scopes of ESD…

  7. A comparison of early versus late initiation of renal replacement therapy in critically ill patients with acute kidney injury

    DEFF Research Database (Denmark)

    2011-01-01

    Introduction: Our aim was to investigate the impact of early versus late initiation of renal replacement therapy (RRT) on clinical outcomes in critically ill patients with acute kidney injury (AKI). Methods: Systematic review and meta-analysis were used in this study. PUBMED, EMBASE, SCOPUS, Web...

  8. Comparison of the Air Force Officer Qualifying Test Form T and Form S: Initial Item- and Subtest-Level Analyses

    Science.gov (United States)

    2017-03-15

    Air Force Officer Qualifying Test Form T and Form S: Initial...Item- and Subtest- Level Analyses March, 2017 Imelda D. Aguilar Air Force Personnel Center Strategic Research and Assessment HQ AFPC...DSYX Prepared for: Laura G. Barron, Ph.D. AFPC/Strategic Research and Assessment Branch (SRAB) Air

  9. Comparison Between Individually and Group-Based Insulin Pump Initiation by Time-Driven Activity-Based Costing.

    Science.gov (United States)

    Ridderstråle, Martin

    2017-07-01

    Depending on available resources, competencies, and pedagogic preference, initiation of insulin pump therapy can be performed on either an individual or a group basis. Here we compared the two models with respect to resources used. Time-driven activity-based costing (TDABC) was used to compare initiating insulin pump treatment in groups (GT) to individual treatment (IT). Activities and cost drivers were identified, timed, or estimated at location. Medical quality and patient satisfaction were assumed to be noninferior and were not measured. GT was about 30% less time-consuming and 17% less cost driving per patient and activity compared to IT. As a batch driver (16 patients in one group) GT produced an upward jigsaw-shaped accumulative cost curve compared to the incremental increase incurred by IT. Taking the alternate cost for those not attending into account, and realizing the cost of opportunity gained, suggested that GT was cost neutral already when 5 of 16 patients attended, and that a second group could be initiated at no additional cost as the attendance rate reached 15:1. We found TDABC to be effective in comparing treatment alternatives, improving cost control and decision making. Everything else being equal, if the setup is available, our data suggest that initiating insulin pump treatment in groups is far more cost effective than on an individual basis and that TDABC may be used to find the balance point.

  10. Comparisons of Stuttering Frequency during and after Speech Initiation in Unaltered Feedback, Altered Auditory Feedback and Choral Speech Conditions

    Science.gov (United States)

    Saltuklaroglu, Tim; Kalinowski, Joseph; Robbins, Mary; Crawcour, Stephen; Bowers, Andrew

    2009-01-01

    Background: Stuttering is prone to strike during speech initiation more so than at any other point in an utterance. The use of auditory feedback (AAF) has been found to produce robust decreases in the stuttering frequency by creating an electronic rendition of choral speech (i.e., speaking in unison). However, AAF requires users to self-initiate…

  11. Education for Sustainable Development in Ethnic Autonomous Areas of China: A Comparison of Two Curriculum Initiatives and Their Educational Implications

    Science.gov (United States)

    Khoo, Yishin

    2015-01-01

    This paper examines the educational implications of two curriculum initiatives in China that have produced curricular materials promoting education for sustainable development (ESD) in minority-populated ethnic autonomous areas in China. The two curriculum projects present distinctive discourses, conceptions, models, frameworks and scopes of ESD…

  12. Energy release and transfer in solar flares: simulations of three-dimensional reconnection

    Energy Technology Data Exchange (ETDEWEB)

    Birn, Joachim [Los Alamos National Laboratory; Fletches, L [UNIV OF GLASGOW; Hesse, M [HGSFC; Neukirch, T [UNIV OF ST. ANDREWS

    2008-01-01

    Using three-dimensional magnetohydrodynamic (MHD) simulations we investigate energy release and transfer in a three-dimensional extension of the standard two-ribbon flare picture. In this scenario reconnection is initiated in a thin current sheet (suggested to form below a departing coronal mass ejection) above a bipolar magnetic field. Two cases are contrasted: an initially force-free current sheet (low beta) and a finite-pressure current sheet (high beta). The energy conversion process from reconnect ion consists of incoming Poynting flux (from the release of magnetic energy) turned into up-and downgoing Poynting flux, enthalpy flux and bulk kinetic energy flux. In the low-beta case, the outgoing Poynting flux is the dominant contribution, whereas the outgoing enthalpy flux dominates in the high-beta case. The bulk kinetic energy flux is only a minor contribution, particularly in the downward direction. The dominance of the downgoing Poynting flux in the low-beta case is consistent with an alternative to the thick target electron beam model for solar flare energy transport, suggested recently by Fletcher and Hudson. For plausible characteristic parameters of the reconnecting field configuration, we obtain energy release time scales and and energy output rates that compare favorably with those inferred from observations for the impulsive phase of flares.

  13. Voriconazole-induced periostitis causing arthralgias mimicking a flare of granulomatosis with polyangiitis.

    Science.gov (United States)

    Gladue, Heather S; Fox, David A

    2013-12-01

    We describe a case of voriconazole-induced periostitis that occurred in a 68-year-old woman with granulomatosis with polyangiitis. Our patient presented with months of severe hip pain limiting her daily activities, which was initially felt to be a flare of her granulomatosis with polyangiitis. However, upon further review, she had an elevated alkaline phosphatase and periostitis on her hip radiograph; voriconazole was held, and within 2 days she had marked improvement in her pain. Although this clinical syndrome is well documented in transplant patients, it is a rare complication in patients with autoimmune disorders. However, it is important because it may cause severe arthralgias that can mimic a flare of rheumatic diseases.

  14. The X-ray emission of solar flares generated by anisotropic electron beams

    Science.gov (United States)

    Bogovalov, S. V.; Kelner, S. R.; Kotov, Y. D.

    1987-12-01

    For three types of the initial angle distribution of fast electrons, energy spectra, directivity, and polarization of the bremsstrahlung have been computed with an account for multiple scattering and energy losses. The influence of Compton scattering and of photoabsorption on the observed hard X-ray emission of solar flares has been investigated. It is obtained that the photon spectrum index depends not only on the spectrum of electrons but also on the registered energy range and on the angle of view of the flare. In the 10 - 40 keV range the spectrum is softer at the limb than in the solar disc centre; in the 60 - 360 keV the situation is reverse, the spectrum being softer in the solar disc centre.

  15. Orphan γ-ray flares from relativistic blobs encountering luminous stars

    Science.gov (United States)

    Banasiński, P.; Bednarek, W.; Sitarek, J.

    2016-11-01

    We propose that {\\gamma} -rays in blazars can be produced during encounters of relativistic blobs of plasma with radiation field produced by luminous stars within (or close to) the jet. The blob is expected to contain relativistic electrons which comptonize stellar radiation to the GeV-TeV energies. Produced {\\gamma} -rays can initiate the Inverse Compton e+/- pair cascade in the stellar radiation. We propose that such a scenario can be responsible for the appearance of the so-called orphan {\\gamma} -ray flares. We show that the relativistic blob/luminous star collision model can explain the appearance of the extreme orphan {\\gamma} -ray flare observed in the GeV and sub-TeV energy range from the flat spectrum radio quasar PKS 1222+21.

  16. Numerical simulation of flare energy build-up and release via Joule dissipation. [solar MHD model

    Science.gov (United States)

    Wu, S. T.; Bao, J. J.; Wang, J. F.

    1986-01-01

    A new numerical MHD model is developed to study the evolution of an active region due to photospheric converging motion, which leads to magnetic-energy buildup in the form of electric current. Because this new MHD model has incorporated finite conductivity, the energy conversion occurs from magnetic mode to thermal mode through Joule dissipation. In order to test the causality relationship between the occurrence of flare and photospheric motion, a multiple-pole configuration with neutral point is used. Using these results it is found that in addition to the converging motion, the initial magnetic-field configuration and the redistribution of the magnetic flux at photospheric level enhance the possibility for the development of a flare.

  17. A comparison of conventional local approach and the short crack approach to fatigue crack initiation at a notch

    Energy Technology Data Exchange (ETDEWEB)

    Ranganathan, Narayanaswami; Leroy, Rene; Tougui, Abdellah [Laboratoire de Mecanique et Rheologie, Universite Francois Rabelais de Tours, Polytech Tours, Departement Mecanique et Conception de Systemes, Tours (France)

    2009-09-15

    Methods to estimate fatigue crack initiation life at a notch tip are compared. The methods used determine the strain amplitudes at the notch tip using Neuber's or Glinka's approximation. In conventional approaches, equivalent-damage levels are determined, using appropriate strain-life relationships coupled with damage-summation models. In the short-crack approach, a crack-like defect is assumed to exist at the notch tip. It is shown that the short-crack concept can be successfully applied to predict crack-initiation behavior at a notch. Model predictions are compared with carefully designed experiments. It is shown that model predictions are very close to experimentally measured lives under an aircraft-wing loading spectrum. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  18. Initial assessment of jaundice in otherwise healthy infants--a comparison of methods in two postnatal units.

    LENUS (Irish Health Repository)

    Allen, N M

    2012-02-01

    Transcutaneous bilirubin (TcB) has the potential to reduce total serum bilirubin (TS) sampling. The principal aim of this study was to determine and compare the number of initial TSB samples (TSBs) in two postnatal units (hospitals A & B) whereby hospital A used TcB and hospital B did not. A secondary aim was to determine the clinical factors that led to initial TSBs exceeding exchange transfusion level in both hospitals. Results demonstrated both hospitals had similar populations and patient numbers following selection criteria. 1645 neonates (10.4%) had one or more TSBs performed in hospital A, versus 2373 neonates (15.1%) in hospital B (p < 0.01). Fourteen neonates in hospital A and 3 neonates in hospital B had initial TSBs above exchange transfusion level. For neonates with TSBs above exchange, preventable factors related to earlier testing and follow up. In routine clinical practice, TcB is associated with a significantly reduced number of TSB measurements. TSB levels above exchange transfusion are linked to preventable factors, in otherwise healthy neonates.

  19. Initial soil moisture effects on flash flood generation - A comparison between basins of contrasting hydro-climatic conditions

    Science.gov (United States)

    Grillakis, M. G.; Koutroulis, A. G.; Komma, J.; Tsanis, I. K.; Wagner, W.; Blöschl, G.

    2016-10-01

    The purpose of this paper is to contribute to the understanding of the importance of the initial soil moisture state for flash flood magnitudes. Four extreme events that occurred in different case study regions were analysed, one winter and one autumn flash flood in the Giofiros and Almirida catchments in Crete, and two summer floods in the Rastenberg catchment in Austria. The hydrological processes were simulated by the spatially distributed flash flood model Kampus. For the Crete cases Kampus model was calibrated against remotely sensed soil moisture while for the Austrian case the model was calibrated against observed runoff. Kampus model was then used to estimate the sensitivity of the stream flow peak to initial soil moisture. The largest of the events analysed (in terms of specific peak discharge) was found to have a sensitivity of less than 0.2% flood peak change per % soil moisture change while the smallest event had a sensitivity of more than 3% flood peak change per % soil moisture change. This suggests that initial soil moisture effects on the flash flood response probably depend on event magnitude rather than on the climate or region. Moreover, the Austrian catchment was found to exhibit a more nonlinear relationship between antecedent soil moisture and the peak discharge than the Cretan catchments which was explained by differences in the soil type.

  20. Optical flare observed in the flaring gamma-ray blazar S5 1044+71

    Science.gov (United States)

    Pursimo, Tapio; Blay, Pere; Telting, John; Ojha, Roopesh

    2017-01-01

    We report optical photometry of the blazar S5 1044+71, obtained with the 2.56m Nordic Optical Telescope in La Palma, to look for any enhanced optical activity associated with a recent flare in the daily averaged gamma-ray flux (ATel#9928).

  1. Flare Ribbons In The Early Phase Of An SDO Flare: Emission Measure And Energetics

    Science.gov (United States)

    Fletcher, Lyndsay; Hannah, I. G.; Hudson, H. S.; Innes, D. E.

    2012-05-01

    We report on the M1.0 flare of 7th August 2010, which displayed extended early phase chromospheric ribbons, well observed by SDO/AIA and RHESSI. Most large flares saturate rapidly in the high-temperature AIA channels, however this event could be followed in unsaturated AIA images for ten minutes in the build-up to and first few minutes of the impulsive phase. Analysis of GOES, RHESSI and SDO/AIA demonstrates the presence of high temperature ( 10MK), compact plasma volumes in the chromospheric flare ribbons, with a column emission measure of on average 3-7 x 1028 cm-5. We construct a time-resolved energy budget for the ribbon plasma, including also SDO/EVE data, and discuss the implications of the observed ribbon properties for flare energisation. This work was supported by the UK’s Science and Technology Facilities Council (ST/1001801), and by the European Commission through the FP7 HESPE project (FP7-2010-SPACE-263086).

  2. Bright X-Ray Flares from the BL Lac Object Markarian 421, Detected with MAXI in 2010 January and February

    Science.gov (United States)

    Isobe, Naoki; Sugimori, Kousuke; Kawai, Nobuyuki; Ueda, Yoshihiro; Negoro, Hitoshi; Sugizaki, Mutsumi; Matsuoka, Masaru; Daikyuji, Arata; Eguchi, Satoshi; Hiroi, Kazuo; Ishikawa, Masaki; Ishiwata, Ryoji; Kawasaki, Kazuyoshi; Kimura, Masashi; Kohama, Mitsuhiro; Mihara, Tatehiro; Miyoshi, Sho; Morii, Mikio; Nakagawa, Yujin E.; Nakahira, Satoshi; Nakajima, Motoki; Ozawa, Hiroshi; Sootome, Tetsuya; Suzuki, Motoko; Tomida, Hiroshi; Tsunemi, Hiroshi; Ueno, Shiro; Yamamoto, Takayuki; Yamaoka, Kazutaka; Yoshida, Atsumasa; MAXI Team

    2010-12-01

    Strong X-ray flares from the blazar Mrk 421 were detected in 2010 January and February through 7-month monitoring with the MAXI GSC. The maximum 2-10 keV flux in the January and February flares was measured to be 120±10 mCrab and 164±17 mCrab, respectively; the latter is the highest among those reported from the object. A comparison of the MAXI and Swift BAT data suggests a convex X-ray spectrum with an approximated photon index of Γ ≳ 2. This spectrum is consistent with a picture that MAXI is observing near the synchrotron peak frequency. The source exhibited a spectral variation during these flares, slightly different from those in previous observations, in which the positive correlation between the flux and hardness was widely reported. By equating the halving decay timescale in the January flare, td ˜ 2.5 × 104 s, to the synchrotron cooling time, the magnetic field was evaluated to be B ˜ 4.5 × 10-2G (δ/10)-1/3, where δ is the jet beaming factor. Assuming that the light crossing time of the emission region is shorter than the doubling rise time, tr ≲ 2 × 104 s, the region size was roughly estimated as R < 6 × 1015 cm (δ/10). These results are consistent with values previously reported. For the February flare, the rise time, tr < 1.3 × 105 s, gives a loose upper limit on the size as R < 4 × 1016 cm (δ/10), although the longer decay time, td ˜ 1.4 × 105s, indicates B ˜ 1.5 × 10-2G (δ/10)-1/3, which is weaker than the previous results. This could be reconciled by invoking a scenario that this flare is a superposition of unresolved events with a shorter timescale.

  3. Searching for Missing Pieces for Solar Flare Forecasting

    Science.gov (United States)

    Leka, K. D.

    2015-12-01

    Knowledge of the state of the solar photospheric magnetic field at a single instant in time does not appear sufficient to uniquely predict the size and timing of impending solar flares. Such knowledge may provide necessary conditions, such as estimates of the magnetic energy needed for a flare to occur. Given the necessary conditions, it is often assumed that the evolution of the field, possibly by only a small amount, may trigger the onset of a flare. We present the results of a study using time series of photospheric vector field data from the Helioseismic and Magnetic Imager (HMI) on NASA's Solar Dynamics Observatory (SDO) to quantitatively parameterize both the state and evolution of solar active regions - their complexity, magnetic topology and energy - as related to solar flare events. We examine both extensive and intensive parameters and their short-term temporal behavior, in the context of predicting flares at various thresholds. Statistical tests based on nonparametric Discriminant Analysis are used to compare pre-flare epochs to a control group of flare-quiet epochs and active regions. Results regarding the type of photospheric signature examined and the efficacy of using the present state vs. temporal evolution to predict solar flares is quantified by standard skill scores. This work is made possible by contracts NASA NNH12CG10C and NOAA/SBIR WC-133R-13-CN-0079.

  4. Exergy analysis of waste emissions from gas flaring

    Directory of Open Access Journals (Sweden)

    Olawale Saheed ISMAIL

    2016-07-01

    Full Text Available Gas flaring produces a stream of waste gases at high temperature and pressure which contains carbon monoxide, Hydrogen Sulphide etc. The resultant effect of which is detrimental to our planet and, consequently, to the life of both the living and the non-living things. It’s well known that gas flaring contributes in no small measure to the global warming. Exergy analysis is applied in this work to analyze waste emissions from gas flaring so as to have a model through which impact of gas flaring can be measured. The study considers both the thermo-mechanical exergy and the chemical exergy of these gases. Relevant data on gas flaring activities in the Niger-Delta region of Nigeria between the periods of fifteen (15 years was obtained from the Nigerian National Petroleum Corporation (NNPC. A computer program (Exergy Calculator was developed based on the equations generated in the Model. Exergy associated with gas flaring activities in Nigeria between the periods of 1998 through 2012 was calculated. The results show that 1 mscf (in thousand cubic feet of flared gases generate 0.000041 MWh of energy leading to a value of 440158.607 MWh of energy for the period under review.The analysis provides important conclusions and recommendations for improving oil platforms operationsin in order to safeguard the environment, health of the populace, and maximize recovered exergy from gas flaring.

  5. Blazar Alerts with the HAWC Online Flare Monitor

    CERN Document Server

    Weisgarber, Thomas

    2015-01-01

    The High Altitude Water Cherenkov (HAWC) Observatory monitors the gamma-ray sky in the 100 GeV to 100 TeV energy range with > 95% uptime and unprecedented sensitivity for a survey instrument. The HAWC Collaboration has implemented an online flare monitor that detects episodes of rapid flaring activity from extragalactic very high energy (VHE) sources in the declination band from -26 to 64 degrees. This allows timely alerts to be sent to multiwavelength instruments without human intervention. The preliminary configuration of the online flare monitor achieves sensitivity to flares of at least 1 hour duration that attain an average flux of 10 times that of the Crab Nebula. While flares of this magnitude are not common, several flares reaching the level of 10 Crab have been observed in the VHE band within the past decade. With its survey capabilities and high duty cycle, HAWC will expand the observational data set on these particularly extreme flares. We characterize the sensitivity of the online flare monitor an...

  6. Development and Optimization of Flow-Cast Magnesium Flare Compositions

    Science.gov (United States)

    1972-06-01

    unsaturated olefins. Resins were studied of ethylene glycol (EG) (52 percent oxgyen) and MA (49 percent); hydroxy- ethyl acrylate...CUttification LINK A I Illumination flares Flares Magnesium Sodium Nitrate Binders Epoxy resins Castable pyrotechnics Flow casting Polyester Vinyl ester UNCLASSTFTFn Security Classification ^^^. ...Lane. Major contributions were made by Erwin M. Jankowiak and Keith Roberson. This technical report has been reviewed and is approved.

  7. Hα Line Profile Asymmetries and the Chromospheric Flare Velocity Field

    Science.gov (United States)

    Kuridze, D.; Mathioudakis, M.; Simões, P. J. A.; Rouppe van der Voort, L.; Carlsson, M.; Jafarzadeh, S.; Allred, J. C.; Kowalski, A. F.; Kennedy, M.; Fletcher, L.; Graham, D.; Keenan, F. P.

    2015-11-01

    The asymmetries observed in the line profiles of solar flares can provide important diagnostics of the properties and dynamics of the flaring atmosphere. In this paper the evolution of the Hα and Ca ii λ8542 lines are studied using high spatial, temporal, and spectral resolution ground-based observations of an M1.1 flare obtained with the Swedish 1 m Solar Telescope. The temporal evolution of the Hα line profiles from the flare kernel shows excess emission in the red wing (red asymmetry) before flare maximum and excess in the blue wing (blue asymmetry) after maximum. However, the Ca ii λ8542 line does not follow the same pattern, showing only a weak red asymmetry during the flare. RADYN simulations are used to synthesize spectral line profiles for the flaring atmosphere, and good agreement is found with the observations. We show that the red asymmetry observed in Hα is not necessarily associated with plasma downflows, and the blue asymmetry may not be related to plasma upflows. Indeed, we conclude that the steep velocity gradients in the flaring chromosphere modify the wavelength of the central reversal in the Hα line profile. The shift in the wavelength of maximum opacity to shorter and longer wavelengths generates the red and blue asymmetries, respectively.

  8. Relationships of a growing magnetic flux region to flares

    NARCIS (Netherlands)

    Schadee, A.; Martin, S.F.; Bentley, R.D.; Antalova, A.; Kucera, A.; Dezs, L.; Gesztelyi, L.; Harvey, K.L.; Jones, H.; Livi, S.H.B.; Wang, J.

    1984-01-01

    Some sites for solar flares are known to develop where new magnetic flux emerges and becomes abutted against opposite polarity pre-existing magnetic flux (review by Galzauskas/1/). We have identified and analyzed the evolution of such flare sites at the boundaries of a major new and growing magnetic

  9. Flare activity on low-mass eclipsing binary GJ 3236*

    Science.gov (United States)

    Šmelcer, L.; Wolf, M.; Kučáková, H.; Bílek, F.; Dubovský, P.; Hoňková, K.; Vraštil, J.

    2017-04-01

    We report the discovery of optical flares on the very low-mass red-dwarf eclipsing binary GJ 3236 and the results of our 2014-2016 photometric campaign. In total, this binary was monitored photometrically in all filters for about 900 h, which has revealed a flare rate of about 0.06 flares per hour. The amplitude of its flares is the largest among those detected in the V band (∼1.3 mag), R band (∼0.8 mag), I band (∼0.2 mag) and clear band (∼0.5 mag). The light curves of GJ 3236 were analysed and the statistics of detected flare events are presented. The energy released during individual flares was calculated as up to 2.4 × 1027 J and compared with other known active stars. The cumulative distribution of flare energies appears to follow a broken power law. The flare activity of this binary also plays an important role in the precise determination of its physical parameters and evolutionary status.

  10. 46 CFR 117.68 - Distress flares and smoke signals.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Distress flares and smoke signals. 117.68 Section 117.68 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS CARRYING MORE... AND ARRANGEMENTS Emergency Communications § 117.68 Distress flares and smoke signals. (a)...

  11. 46 CFR 180.68 - Distress flares and smoke signals.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Distress flares and smoke signals. 180.68 Section 180.68... signals. (a) Oceans, coastwise, limited coastwise, and Great Lakes routes. A vessel on an oceans, coastwise, limited coastwise, or Great Lakes route must carry— (1) Six hand red flare distress signals...

  12. An Interactive Multi-instrument Database of Solar Flares

    Science.gov (United States)

    Sadykov, Viacheslav M.; Kosovichev, Alexander G.; Oria, Vincent; Nita, Gelu M.

    2017-07-01

    Solar flares are complicated physical phenomena that are observable in a broad range of the electromagnetic spectrum, from radio waves to γ-rays. For a more comprehensive understanding of flares, it is necessary to perform a combined multi-wavelength analysis using observations from many satellites and ground-based observatories. For an efficient data search, integration of different flare lists, and representation of observational data, we have developed the Interactive Multi-Instrument Database of Solar Flares (IMIDSF, https://solarflare.njit.edu/). The web-accessible database is fully functional and allows the user to search for uniquely identified flare events based on their physical descriptors and the availability of observations by a particular set of instruments. Currently, the data from three primary flare lists (Geostationary Operational Environmental Satellites, RHESSI, and HEK) and a variety of other event catalogs (Hinode, Fermi GBM, Konus-W IND, the OVSA flare catalogs, the CACTus CME catalog, the Filament eruption catalog) and observing logs (IRIS and Nobeyama coverage) are integrated, and an additional set of physical descriptors (temperature and emission measure) is provided along with an observing summary, data links, and multi-wavelength light curves for each flare event since 2002 January. We envision that this new tool will allow researchers to significantly speed up the search of events of interest for statistical and case studies.

  13. Solar Chromospheric Flares: Observations in Ly-lpha and Hlpha and Radiative Hydrodynamic Simulations

    Science.gov (United States)

    Rubio da Costa, Fatima

    2011-03-01

    . Analyzing the available data in other wavelengths, we made a morphological study of the active region from three hours before the flare to seven hours after it. The results obtained by observations, both in the form of integrated intensity as a function of time, and detailed line profiles, motivated the second part of the thesis. In this, we used a radiative transfer code (Gouttebroze et al. 1978) applying different atmospheric models as input parameters in order to compute the hydrogen spectral lines and study how they are affected by the temperature and microturbulent stratification. In particular, the intensity of the Ly-α and Hα lines is related to the temperature stratification of the atmospheric model, the position of the transition region being a key factor. The variation of the microturbulent velocity does not significantly affect the resulting intensities, but we observed that an increase of the microturbulent velocity broadens the line profiles. The RADYN Radiative HydroDynamic code (Allred et al. 2005) was applied to solar flares, modelling a flare loop from its footpoints in the photosphere to its apex in the corona by adding non-thermal heating at the lower atmosphere and soft X-ray irradiation. The majority of this work was to deal with investigating the dynamical response of the solar chromosphere to energy injected in the form of non-thermal electrons during solar flares. We studied the flare energy transport and radiation production in the chromosphere as well as the Hα and Ly-α emission. The Ly-α intensity is affected by the flux of the initial beam of electrons injected at the top of the loop, while the Hα intensity appears to be less affected by the flare model. Comparing the observational results in Lyα and Hα with the computed ones from the radiative code and the RADYN code, we found that the RADYN code fits better the Hα intensities to the observations than the Lyα intensities, concluding that the code gives a better description of processes

  14. TH-A-9A-05: Initial Setup Accuracy Comparison Between Frame-Based and Frameless Stereotactic Radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, T; Sheu, R; Todorov, B; Green, S; Blacksburg, S; Lo, Y [Mount Sinai Medical Center, New York, NY (United States)

    2014-06-15

    Purpose: To evaluate initial setup accuracy for stereotactic radiosurgery (SRS) between Brainlab frame-based and frameless immobilization system, also to discern the magnitude frameless system has on setup parameters. Methods: The correction shifts from the original setup were compared for total 157 SRS cranial treatments (69 frame-based vs. 88 frameless). All treatments were performed on a Novalis linac with ExacTrac positioning system. Localization box with isocenter overlay was used for initial setup and correction shift was determined by ExacTrac 6D auto-fusion to achieve submillimeter accuracy for treatment. For frameless treatments, mean time interval between simulation and treatment was 5.7 days (range 0–13). Pearson Chi-Square was used for univariate analysis. Results: The correctional radial shifts (mean±STD, median) for the frame and frameless system measured by ExacTrac were 1.2±1.2mm, 1.1mm and 3.1±3.3mm, 2.0mm, respectively. Treatments with frameless system had a radial shift >2mm more often than those with frames (51.1% vs. 2.9%; p<.0001). To achieve submillimeter accuracy, 85.5% frame-based treatments did not require shift and only 23.9% frameless treatment could succeed with initial setup. There was no statistical significant system offset observed in any direction for either system. For frameless treatments, those treated ≥ 3 days from simulation had statistically higher rates of radial shifts between 1–2mm and >2mm compared to patients treated in a shorter amount of time from simulation (34.3% and 56.7% vs. 28.6% and 33.3%, respectively; p=0.006). Conclusion: Although image-guided positioning system can also achieve submillimeter accuracy for frameless system, users should be cautious regarding the inherent uncertainty of its capability of immobilization. A proper quality assurance procedure for frameless mask manufacturing and a protocol for intra-fraction imaging verification will be crucial for frameless system. Time interval between

  15. Implications of RHESSI Flare Observations for Magnetic Reconnection Models

    Science.gov (United States)

    Holman, Gordon D.; Sui, Linhui; Dennis, Brian R.

    2004-01-01

    The Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observations of the 2002 April 15 solar flare and related flares provide compelling evidence for the formation of a large-scale, reconnecting current sheet in at least some flares. We describe the observed evolution of the April 15 flare in terms of magnetic reconnection models. We argue that the flare most likely evolved through magnetic geometries associated with super-slow reconnection (early rise phase), fast reconnection (impulsive phase), and slow reconnection (gradual phase). We also provide evidence for X-ray brightenings within the evolving current sheet, possibly induced by the tearing mode instability. This work was supported in part by the RHESSI Program and NASA's Sun-Earth Connection Program. This work would not have been possible without the dedicated efforts of the entire RHESSI team.

  16. EUV Flare Activity in Late-Type Stars

    CERN Document Server

    Audard, M; Drake, J J; Kashyap, V L; Audard, Marc; Guedel, Manuel; Drake, Jeremy J.

    2000-01-01

    \\textit{Extreme Ultraviolet Explorer} Deep Survey observations of cool stars (spectral type F to M) have been used to investigate the distribution of coronal flare rates in energy and its relation to activity indicators and rotation parameters. Cumulative and differential flare rate distributions were constructed and fitted with different methods. Power laws are found to approximately describe the distributions. A trend toward flatter distributions for later-type stars is suggested in our sample. Assuming that the power laws continue below the detection limit, we have estimated that the superposition of flares with radiated energies of about $10^{29}-10^{31}$ergs could explain the observed radiative power loss of these coronae, while the detected flares are contributing only $\\approx 10$%. While the power-law index is not correlated with rotation parameters (rotation period, projected rotational velocity, Rossby number) and only marginally with the X-ray luminosity, the flare occurrence rate is correlated wit...

  17. Solar Flares and the High Energy Solar Spectroscopic Imager (HESSI)

    Science.gov (United States)

    Holman, Gordon D.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Solar flares are the biggest explosions in the solar system. They are important both for understanding explosive events in the Universe and for their impact on human technology and communications. The satellite-based HESSI is designed to study the explosive release of energy and the acceleration of electrons, protons, and other charged particles to high energies in solar flares. HESSI produces "color" movies of the Sun in high-energy X rays and gamma rays radiated by these energetic particles. HESSI's X-ray and gamma-ray images of flares are obtained using techniques similar to those used in radio interferometry. Ground-based radio observations of the Sun provide an important complement to the HESSI observations of solar flares. I will describe the HESSI Project and the high-energy aspects of solar flares, and how these relate to radio astronomy techniques and observations.

  18. The investigation of the Neupert effect in two solar flares

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The Neupert effect suggests a flare model in which the nonthermal emissions are produced by energetic electrons which heat lower corona and chromosphere to produce the thermal emissions. Based on this concept, we investigate the Neupert effect to test the correlation between the hard X-ray spectral index and the time rate of the UV flare area at 1600 or 171 . Using the T RACE and RHESSI observations, we explore these quantities for two solar flares, one on March 14, 2002 and the other on November 1, 2003. The negative dependence between the spectral index and the time rate of the UV flare area is found, especially during the hard X-ray sub-peaks. This finding indicates that the electron-beam-driven heating plays a prominent role in the UV emission of these two flares.

  19. The initial magnetic susceptibility of polydisperse ferrofluids: A comparison between experiment and theory over a wide range of concentration

    Science.gov (United States)

    Solovyova, Anna Y.; Goldina, Olga A.; Ivanov, Alexey O.; Lebedev, Aleksandr V.; Elfimova, Ekaterina A.

    2016-08-01

    Temperature dependencies of the static initial magnetic susceptibility for ferrofluids at various concentrations are studied using experiment and statistical-mechanical theories. Magnetic susceptibility measurements are carried out for twelve samples of magnetite-based fluids stabilized with oleic acid over a wide range of temperatures (210 K ≲T ≲ 390 K); all samples have the same granulometric composition but different volume ferroparticle concentrations (0.2 ≲ φ ≲ 0.5). Experimental results are analyzed using three theories: the second-order modified mean-field theory (MMF2) [A. O. Ivanov and O. B. Kuznetsova, Phys. Rev. E 64, 41405 (2001)]; its correction for polydisperse ferrofluids arising from Mayer-type cluster expansion and taking into account the first terms of the polydisperse second virial coefficient [A. O. Ivanov and E. A. Elfimova, J. Magn. Magn. Mater 374, 327 (2015)]; and a new theory based on MMF2 combined with the first terms of the polydisperse second and third virial contributions to susceptibility. It turns out that the applicability of each theory depends on the experimental sample density. If twelve ferrofluid samples are split into three groups of strong, moderate, and low concentrated fluids, the temperature dependences of the initial magnetic susceptibility in each group are very precisely described by one of the three theories mentioned above. The determination of a universal formula predicting a ferrofluid susceptibility over a broad range of concentrations and temperatures remains as a challenge.

  20. Comparison of Video-Assisted Thoracoscopic Surgery and Intrapleural Urokinase as an Initial Treatment for Parapneumonic Effusion and Thoracic Empyema

    Directory of Open Access Journals (Sweden)

    Shungo Yukumi

    2014-05-01

    Full Text Available Introduction: The treatment of complicated parapneumonic effusion (PPE and thoracic empyema (TE is controversial; and the choice of treatment after confirming the failure of simple drainage remains unclear. The purpose of this study was to compare the outcomes of intrapleural urokinase (UK administration and video-assisted thoracoscopic surgery (VATS as initial treatment options for PPE and TE. Materials and Methods: We retrospectively reviewed and compared the data of 20 patients with PPE and TE diagnosed between January 2010 and December 2012 at our hospital, dividing them on the basis of the initial treatment into a video-assisted thoracoscopic surgery (VATS group (n=9 and UK group (n=11. Results: Age was the only statistically different parameter between both groups (P=0.025; with the mean age of the VATS and UK groups being 64 and 76 years, respectively. There was no significant difference in the duration of drainage or success rate between the UK or VATS groups. Although no statistically significant differences (P=0.20 were observed, duration of hospital stay was longer in the UK group (21 and 28 day for VATS and UK, respectively. Conclusion: VATS for PPE and TE may shorten the duration of hospital stay.However, UK administration may be used for selective patients because it is considered to yield outcomes similar to VATS.

  1. Comparison of initial permeability of MgCuZn ferrites sintered by both conventional and microwave methods

    Energy Technology Data Exchange (ETDEWEB)

    Madhuri, W; Penchal Reddy, M; Rammanohar Reddy, N; Siva Kumar, K V [Ceramic Composite Materials Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur-515 003 (India); Murthy, V R K, E-mail: sivakumar.sivani@gmail.co [Microwave Laboratory, Department of Physics, Indian Institute of Technology, Chennai-600 036 (India)

    2009-08-21

    NiCuZn ferrites are widely employed for many electronic applications, but can be replaced by MgCuZn ferrites owing to their superior properties like low magnetostriction, environmental stability, low stress sensitivity and low cost. In view of this, a series of non-stoichiometric MgCuZn ferrites (Mg{sub 0.5-x}Cu{sub x}Zn{sub 0.5}Fe{sub 1.9}O{sub 4-{delta}} with x = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25) have been successfully synthesized by both conventional and microwave sintering techniques. The non-stoichiometry was intentionally introduced into the ferrites to ensure high resistivity of the samples. X-ray diffraction patterns confirm the single phase spinel structure in both cases. The elemental composition of these ferrites was analysed by energy-dispersive x-ray spectrometry. The samples sintered by the microwave technique were found to be denser than the conventionally sintered samples. The initial permeability of MgCuZn ferrites was studied with an increase in copper concentration from x = 0.0 to 0.25. The temperature variation of the initial permeability of these samples was carried out from 30 {sup 0}C to 150 {sup 0}C. The results are discussed in the light of microstructure variations of the conventionally and microwave sintered samples. The phenomena involved in microwave sintering are also discussed.

  2. The initial Helium content of Galactic Globular Cluster stars from the R-parameter comparison with the CMB constraint

    CERN Document Server

    Cassisi, S; Irwin, A W

    2003-01-01

    Recent precise determinations of the primordial He-abundance (Y_p) from cosmic microwave background (CMB) analyses and cosmological nucleosynthesis computations, provide Y_p=0.248$\\pm$0.001. On the other hand, recent works on the initial He-abundance of Galactic globular cluster (GGC) stars, making use of the R parameter as He-indicator, have consistently obtained $Y_{GGC}\\sim$0.20. In light of this serious discrepancy that casts doubt on the adequacy of low mass He-burning stellar models, we have rederived the initial He-abundance for stars in two large samples of GGCs, by employing theoretical models computed using new and more accurate determinations of the Equation of State for the stellar matter, and of the uncertain $^{12}$C$(\\alpha,\\gamma)^{16}$O reaction rate. Our models include semiconvection during the central convective He-burning phase, while the breathing pulses are suppressed, in agreement with the observational constraints coming from the measurements of the R_2 parameter in a sample of cluster...

  3. On the polarization properties of magnetar giant flare pulsating tails

    CERN Document Server

    Yang, Yuan-Pei

    2015-01-01

    Three giant flares have been detected so far from soft gamma-ray repeaters, each characterized by an initial short hard spike and a pulsating tail. The observed pulsating tails are characterized by a duration of $\\sim100\\,\\rm{s}$, an isotropic energy of $\\sim 10^{44}\\,\\rm{erg}$, and a pulse period of a few seconds. The pulsating tail emission likely originates from the residual energy after the intense energy release during the initial spike, which forms a trapped fireball composed of a photon-pair plasma in a closed field line region of the magnetars. Observationally the spectra of pulsating tails can be fitted by the superposition of a thermal component and a power-law component, with the thermal component dominating the emission in the early and late stages of the pulsating tail observations. In this paper, assuming that the trapped fireball is from a closed field line region in the magnetosphere, we calculate the atmosphere structure of the optically-thick trapped fireball and the polarization properties ...

  4. On the status and comparison of glucose intolerance in female breast cancer patients at initial diagnosis and during chemotherapy through an oral glucose tolerance test.

    Directory of Open Access Journals (Sweden)

    Lin-jie Lu

    Full Text Available AIMS: This study is to estimate the status and comparison of glucose intolerance in female breast cancer patients at initial diagnosis and during chemotherapy through an oral glucose tolerance test (OGTT, as well as to learn the effect of chemotherapy on the glucose metabolism of breast cancer patients. METHODS: All the 79 breast cancer patients at initial diagnosis, with the mean age of 53.2 years, and 96 breast cancer patients before the 5th or 6th cycle of chemotherapy, with the mean age of 51.5 years, participated in the study from December 2012 to October 2013. After an overnight fast, participants underwent OGTT test, and fasting and 2-hour glucose levels were measured to identify undiagnosed diabetes and prediabetes (i.e., impaired fasting glucose or impaired glucose tolerance in them. Previously diagnosed diabetes among the female breast cancer patients was determined on the self-report and the medical record. RESULTS: The overall incidences of total normal glucose tolerance, prediabetes, diabetes in female breast cancer patients at initial diagnosis and during chemotherapy were 24.1% and 38.5% (p0.05, respectively, and the differences of normal glucose tolerance and prediabetes instead of diabetes between the two groups were statistically significant. About 84% of the total diabetes and prediabetes in the female breast cancer patients at initial diagnosis and 79.7% of those during chemotherapy need to be diagnosed with OGTT. CONCLUSIONS: Breast cancer patients have high incidences of diabetes and prediabetes. After chemotherapy even with steroids, some breast cancer patients with abnormal glucose metabolism may even become normal. Isolated hyperglycemia 2 hours after glucose loading is common, and OGTT should be made for breast cancer patients at initial diagnosis and during chemotherapy.

  5. Observations and Modelling of the Pre-flare Period of the 29 March 2014 X1 Flare

    Science.gov (United States)

    Woods, M. M.; Harra, L. K.; Matthews, S. A.; Mackay, D. H.; Dacie, S.; Long, D. M.

    2017-02-01

    On 29 March 2014, NOAA Active Region (AR) 12017 produced an X1 flare that was simultaneously observed by an unprecedented number of observatories. We have investigated the pre-flare period of this flare from 14:00 UT until 19:00 UT using joint observations made by the Interface Region Imaging Spectrometer (IRIS) and the Hinode Extreme Ultraviolet Imaging Spectrometer (EIS). Spectral lines providing coverage of the solar atmosphere from the chromosphere to the corona were analysed to investigate pre-flare activity within the AR. The results of the investigation have revealed evidence of strongly blue-shifted plasma flows, with velocities up to 200 km s^{-1}, being observed 40 minutes prior to flaring. These flows are located along the filament present in the active region and are both spatially discrete and transient. In order to constrain the possible explanations for this activity, we undertake non-potential magnetic field modelling of the active region. This modelling indicates the existence of a weakly twisted flux rope along the polarity inversion line in the region where a filament and the strong pre-flare flows are observed. We then discuss how these observations relate to the current models of flare triggering. We conclude that the most likely drivers of the observed activity are internal reconnection in the flux rope, early onset of the flare reconnection, or tether-cutting reconnection along the filament.

  6. Constraints on Stochastic Electron Acceleration Process from RHESSI Solar Flare Observations

    Science.gov (United States)

    Chen, Q.; Petrosian, V.

    2011-12-01

    Bremsstrahlung hard X-ray (HXR) emission provides the most direct information for diagnosing the electron acceleration and transport processes in solar flares. HXR observations have indicated that the majority of nonthermal electrons are accelerated near the top of the flaring loop, as evidenced by the distinct coronal loop top (LT) source, and move downward along the loop to the footpoints (FPs). This can be naturally accounted for by the model of stochastic acceleration, in which electrons are scattered and accelerated near the LT region by plasma waves or turbulence. In this work, we aim to better understand the role of turbulence in scattering and accelerating electrons in solar flares based on imaging spectroscopic observations from the RHESSI satellite and theoretical modeling of the process of stochastic acceleration by turbulence. We show how the RHESSI observations can constrain some important characteristics of turbulence. In particular, we obtain the accelerated electron spectra from the LT source in the regularized electron maps, which is determined by the turbulence acceleration rate, and also obtain the escape time from the LT and FP spectral difference, which is related to the pitch angle scattering rate of electrons by turbulence. Furthermore, comparison of the electron spectra obtained from solution of the Fokker-Planck equation describing the acceleration process with the directly observed LT electron spectra in principle allows us to determine whether the required acceleration rate by turbulence is consistent with the scattering rate. We will present results from several RHESSI flares with different LT spectral hardness relative to the FPs and discuss the physical implication for the electron acceleration and transport processes.

  7. The timing of relativistic proton acceleration in the 20 January 2005 flare

    Science.gov (United States)

    Simnett, G. M.

    2006-01-01

    Understanding the energy budget in large solar flares requires a good knowledge of how and where the energetic charged particles are accelerated. If they are mainly accelerated by a Coronal Mass Ejection (CME)-driven shock, then they do not have to derive their energy from the flare region. Conversely, if the CME does not accelerate the particles, then the energy must be provided from elsewhere. Resolution of this controversial issue may be aided if we can study events where the timing of the energetic charged particle acceleration may be tightly constrained by the data. We report here on high resolution observations of such an event. The intense ground level solar proton event of 20 January, 2005 had a rise to maximum at the South Pole of around 5 min, with a similar decay time to 1/3 maximum. This suggests that the magnetic connection from the Sun to the Earth was good and that the proton injection was impulsive on the timescale of a few minutes or less. Comparison of the proton onset time with the solar electromagnetic emissions which accompany large flares, together with observations of the coronal mass ejection seen around the injection time suggests that the CME was not responsible for the relativistic ion acceleration. The near-relativistic (~250 keV) electron intensity onset was some 8 min later than the proton onset. Implications of this on the relative injection time of the particles are discussed. It is concluded that while the relativistic protons were not accelerated by the CME-driven shock, the CME may have influenced the release of both flare-accelerated protons and electrons into the interplanetary medium.

  8. Deterministically Driven Avalanche Models of Solar Flares

    CERN Document Server

    Strugarek, Antoine; Joseph, Richard; Pirot, Dorian

    2014-01-01

    We develop and discuss the properties of a new class of lattice-based avalanche models of solar flares. These models are readily amenable to a relatively unambiguous physical interpretation in terms of slow twisting of a coronal loop. They share similarities with other avalanche models, such as the classical stick--slip self-organized critical model of earthquakes, in that they are driven globally by a fully deterministic energy loading process. The model design leads to a systematic deficit of small scale avalanches. In some portions of model space, mid-size and large avalanching behavior is scale-free, being characterized by event size distributions that have the form of power-laws with index values, which, in some parameter regimes, compare favorably to those inferred from solar EUV and X-ray flare data. For models using conservative or near-conservative redistribution rules, a population of large, quasiperiodic avalanches can also appear. Although without direct counterparts in the observational global st...

  9. The Flare-ona of EK Draconis

    CERN Document Server

    Ayres, Thomas R

    2015-01-01

    EK Draconis (HD 129333: G1.5 V) is a well-known young (50 Myr) solar analog. In 2012, Hubble Space Telescope returned to EK Dra to follow up a far-ultraviolet (FUV) SNAPshot visit by Cosmic Origins Spectrograph (COS) two years earlier. The brief SNAP pointing had found surprisingly redshifted, impulsively variable subcoronal "hot-line" emission of Si IV 140 nm (T~ 80,000 K). Serendipitously, the 2012 follow-on program witnessed one of the largest FUV flares ever recorded on a sunlike star, which again displayed strong redshifts (downflows) of 30-40 km/s, even after compensating for small systematics in the COS velocity scales, uncovered through a cross-calibration by Space Telescope Imaging Spectrograph (STIS). The (now reduced, but still substantial) ~10 km/s hot-line redshifts outside the flaring interval did not vary with rotational phase, so cannot be caused by "Doppler Imaging" (bright surface patches near a receding limb). Density diagnostic O IV] 140 nm multiplet line ratios of EK Dra suggest log(Ne)~ ...

  10. Developing a Construct to Evaluate Flares in Rheumatoid Arthritis: A Conceptual Report of the OMERACT RA Flare Definition Working Group

    DEFF Research Database (Denmark)

    Alten, Rieke; Choy, Ernest H; Christensen, Robin

    2011-01-01

    Rheumatoid arthritis (RA) patients and healthcare professionals (HCP) recognize that episodic worsening disease activity, often described as a "flare," is a common feature of RA that can contribute to impaired function and disability. However, there is no standard definition to enable measurement...... of its intensity and impact. The conceptual framework of the Outcome Measures in Rheumatology Clinical Trials (OMERACT) RA Flare Definition Working Group includes an anchoring statement, developed at OMERACT 9 in 2008: "flare in RA" is defined as worsening of signs and symptoms of sufficient intensity...... is intended to enhance patient-HCP communication. This article describes the conceptual framework being used by the OMERACT RA Flare Definition Working Group in developing a standardized method for description and measurement of "flare in RA" to guide individual patient treatment....

  11. Solar and Stellar Flares and Their Effects on Planets

    Science.gov (United States)

    Shibata, Kazunari

    2015-08-01

    Recent space observations of the Sun revealed that the solar atmosphere is full of explosions, such as flares and flare-like phenomena. These flares generate not only strong electromagnetic emissions but also nonthermal particles and bulk plasma ejections, which sometimes lead to geomagnetic storms and affect terrestrial environment and our civilization, damaging satellite, power-grids, radio communication etc. Solar flares are prototype of various explosions in our universe, and hence are important not only for geophysics and environmental science but also for astrophysics. The energy source of solar flares is now established to be magnetic energy stored near sunspots. There is now increasing observational evidence that solar flares are caused by magnetic reconnection, merging of anti-parallel magnetic field lines and associated magneto-plasma dynamics (Shibata and Magara 2011, Living Review). It has also been known that many stars show flares similar to solar flares, and often such stellar flares are much more energetic than solar flares. The total energy of a solar flare is typically 10^29 - 10^32 erg. On the other hand, there are much more energetic flares (10^33 - 10^38 erg) in stars, especially in young stars. These are called superflares. We argue that these superflares on stars can also be understood in a unified way based on the reconnection mechanism. Finally we show evidence of occurrence of superflares on Sun-like stars according to recent stellar observations (Maehara et al. 2012, Nature, Shibayama et al. 2013), which revealed that superflares with energy of 10^34 - 10^35 erg (100 - 1000 times of the largest solar flares) occur with frequency of once in 800 - 5000 years on Sun-like stars which are very similar to our Sun. Against the previous belief, these new observations as well as theory (Shibata et al. 2013) suggest that we cannot deny the possibility of superflares on the present Sun. Finally, we shall discuss possible impacts of these superflares

  12. Study of white-light flares observed by Hinode

    Institute of Scientific and Technical Information of China (English)

    Hai-Min Wang

    2009-01-01

    White-light flares are considered to be the most energetic flaring events that are observable in the optical broad-band continuum of the solar spectrum. They have not been commonly observed. Observations of white-light flares with sub-arcsecond resolution have been very rare. The continuous high resolution observations of Hinode provide a unique opportunity to systematically study the white-light flares with a spatial resolution around 0.2 arcsec. We surveyed all the flares above GOES magnitude C5.0 since the launch of Hinode in 2006 October. 13 of these kinds of flares were covered by the Hinode G-band observations. We analyzed the peak contrasts and equivalent areas (calculated via integrated excess emission contrast) of these flares as a function of the GOES X-ray flux, and found that the cut-off visibility is likely around M1 flares under the observing limit of Hinode. Many other observational and physical factors should affect the visibility of white-light flares; as the observing conditions are improved, smaller flares are likely to have detectable white-light emissions. We are cautious that this limiting visibility is an overestimate, because G-band observations contain emissions from the upper atmosphere.Among the 13 events analyzed, only the M8.7 flare of 2007 June 4 had near-simultaneous observations in both the G-band and the blue continuum. The blue continuum had a peak contrast of 94% vs. 175% in G-band for this event. The equivalent area in the blue continuum is an order of magnitude lower than that in the G-band. Very recently, Jess et al.studied a C2.0 flare with a peak contrast of 300% in the blue continuum. Compared to the events presented in this letter, that event is probably an unusual white-light flare: a very small kernel with a large contrast that can be detected in high resolution observations.

  13. Diagnosing and quantification of acute alcohol intoxication. Comparison of dual-energy CT with biochemical analysis. Initial experience

    Energy Technology Data Exchange (ETDEWEB)

    Korkusuz, H. [Frankfurt Univ. Hospital (Germany). Dept. of Nuclear Medicine; Abbas Raschidi, B.; Keese, D.; Kromen, W.; Bauer, R.W.; Vogl, T.J. [Frankfurt Univ. Hospital (Germany). Dept. of Diagnostic and Interventional Radiology; Namgaladze, D. [Frankfurt Univ. (Germany). Dept. of Biochemistry

    2012-12-15

    Purpose: To quantify the correlation between fat content of an acute alcohol intoxication and the difference of computer tomography attenuation value in dual-energy CT in comparison to biochemical triglyceride analysis and to evaluate qualitatively the value of DECT in the diagnosis of fatty liver caused by ethanol-dosage in rats. Materials and Methods: DECT at 140 kV and 80 kV was performed on 20 rats before and two days after the administration of 3 ml of 50 % ethanol. The CT attenuation value in the livers at 140 kV, 80 kV and the differences between them in Hounsfield units ({Delta}H) were collected. Parts of the liver (100 mg) were measured in biochemical triglyceride analysis as the reference standard. A blood sample was also taken to measure specific liver enzymes. Results: Linear correlation between biochemical triglyceride analysis and CT density of {Delta}H was found (r = 0.949). 140 kV attenuation data were between 44 HU and 61.3 HU, 80 kV attenuation data were between 58.4 HU and 64.7 HU, and {Delta}H data were between 3.4 HU and 14.4 HU (p {<=} 0.037). The biochemical triglyceride analysis data were between 7.1 mg/g and 41.1 mg/g. The hepatic enzymes serum aspartate (ASAT) aminotransferase and alanine aminotransferase (ALAT) were elevated in all rats. ASAT correlated directly with {Delta}HU (r = -0.86). Conclusion: DECT provides a non-invasive method to determine and evaluate hepatic fat content after acute alcohol intoxication. It provides the possibility to detect and quantify the hepatic fat content of liver graft. (orig.)

  14. Scapholunate kinematics of asymptomatic wrists in comparison with symptomatic contralateral wrists using four-dimensional CT examinations: initial clinical experience

    Energy Technology Data Exchange (ETDEWEB)

    Demehri, Shadpour; Hafezi-Nejad, Nima; Morelli, John N.; Thakur, Uma; Eng, John [Johns Hopkins University, Musculoskeletal Radiology, Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD (United States); Lifchez, Scott D.; Shores, Jaimie T. [Johns Hopkins University, Department of Plastic and Reconstructive Surgery, Baltimore, MD (United States); Means, Kenneth R. [MedStar Union Memorial Hospital, The Curtis National Hand Center, Baltimore, MD (United States)

    2016-04-15

    Using four-dimensional CT scan (4DCT), we aimed at showing the kinematics of scapholunate (SL) interval in asymptomatic wrists in comparison with symptomatic contralateral wrists with inconclusive radiographic findings. This is an IRB approved, HIPPA compliant, retrospective study. Patients suspected of SL interosseous ligament (SLIL) injuries were referred for further evaluation of chronic wrist pain (>3 months). Twelve wrists (11 subjects) with chronic symptoms and inconclusive plain radiographs and 10 asymptomatic wrists (in 10 different subjects) were scanned using 4DCT. The minimum SL interval was measured during three wrist motions: relaxed-to-clenched fist, flexion-to-extension, and radial-to-ulnar-deviation. Changes were recorded using double-oblique multiplanar reformation technique. We extracted the normal limits of the SL interval as measured by dynamic CT scanning during active motion in asymptomatic wrists. In asymptomatic wrists, the average SL interval was observed to be smaller than 1 mm during all motions. In symptomatic wrists, during exams performed with clenched fist (SL interval (mean ± SD) = 2.53 ± 1.19 mm), extension (2.54 ± 1.48 mm) or ulnar deviation (2.06 ± 1.12 mm), the average SL interval was more than 2 mm. In contrast to symptomatic wrists, no significant change in SL interval measurements was detected during wrist motions in asymptomatic wrists. There was a mild to moderate correlation between SL interval change and presence/absence of symptoms (point-biserial correlation coefficients: 0.29-0.55). In patients with wrist pain suspicious for SLIL injury and inconclusive radiographs, SL interval increase can be detected with 4DCT in the symptomatic wrist compared to the asymptomatic wrist. (orig.)

  15. Effect of flaring of natural gas in oil fields of Assam on rice cultivation.

    Science.gov (United States)

    Sharma, K K; Hazarika, S; Kalita, B; Sharma, B

    2011-07-01

    Assam (India) is endowed with natural resources like oil, coal and natural gas. The crude oil, one of the most precious natural resources, is found in the districts of upper Assam. During the process of extraction of crude oil, low-pressure natural gas is burnt in the air. Most of the oil wells in upper Assam are located near rice fields and therefore, rice crop grown near the oil wells is exposed to light uninterruptedly causing grain sterility resulting significant loss in grain yield. To identify promising varieties for these areas, we studied the effect of flare on rice varieties with different photoperiod sensitivity. The high light intensity and increased light hours were the factors responsible for substantial loss in grain yield near the flare resulting from delay in flower initiation, reduction of panicle length, having less number of grains per panicle and more grain sterility. To prevent significant loss in yield, photoperiod-sensitive traditional and improved rice varieties should not be grown up to the distance of 80 and 100 m, respectively from the boundary wall of the flare pit. Modern weakly-photoperiod sensitive varieties like Ranjti and Mahsuri can be grown 40 m away from the wall while modern photoperiod insensitive variety like Jaya, can be cultivated 20 m away from the wall without significant loss in yield.

  16. The impulsive phase of magnetar giant flares: assessing linear tearing as the trigger mechanism

    CERN Document Server

    Elenbaas, Chris; Turolla, Roberto; Heyl, Jeremy

    2015-01-01

    Giant $\\gamma$-ray flares comprise the most extreme radiation events observed from magnetars. Developing on (sub)millisecond timescales and generating vast amounts of energy within a fraction of a second, the initial phase of these extraordinary bursts present a significant challenge for candidate trigger mechanisms. Here we assess and critically analyse the linear growth of the relativistic tearing instability in a globally twisted magnetosphere as the trigger mechanism for giant $\\gamma$-ray flares. Our main constraints are given by the observed emission timescales, the energy output of the giant flare spike, and inferred dipolar magnetic field strengths. We find that the minimum growth time of the linear mode is comparable to the $e$-folding rise time, i.e. $\\sim10^{-1}$ ms. With this result we constrain basic geometric parameters of the current sheet. We also discuss the validity of the presumption that the $e$-folding emission timescale may be equated with the growth time of an MHD instability.

  17. Ejection Lorentz Factor and Radiation Location of X-ray Flares

    CERN Document Server

    Mu, Hui-Jun; Xi, Shao-Qiang; Lin, Ting-Ting; Wang, Yuan-Zhu; Liang, Yun-Feng; Lv, Lian-Zhong; Zhang, Jin; Liang, En-Wei

    2016-01-01

    We present time-resolved spectral analysis of the steep decay segments of 29 bright X-ray flares of gamma-ray bursts (GRBs) observed with the Swift/X-ray telescope, and model their lightcurves and spectral index evolution behaviors with the curvature effect model. Our results show that the observed rapid flux decay and strong spectral index evolution with time can be well fit with this model, and the derived characteristic timescales ($t_c$) are in the range of $33\\sim 264$ seconds. Using an empirical relation between the peak luminosity and the Lorentz factor derived from the prompt gamma-rays, we estimate the Lorentz factors of the flares ($\\Gamma_{\\rm X}$). We obtain $\\Gamma_{\\rm X}=17\\sim 87$ with a median value of $52$, which is smaller than the initial Lorentz factors of prompt gamma-ray fireballs. With the derived $t_c$ and $\\Gamma_{\\rm X}$, we constrain the radiating regions of 13 X-ray flares, yielding $R_{\\rm X}=(0.2\\sim 1.1)\\times 10^{16}$ cm, which are smaller than the radii of the afterglow fireb...

  18. Optical Flares from the Tidal Disruption of Stars by Massive Black Holes

    CERN Document Server

    Strubbe, Linda E

    2009-01-01

    A star that wanders too close to a massive black hole (BH) is shredded by the BH's tidal gravity. Stellar gas falls back to the BH, releasing a flare of energy. In anticipation of upcoming transient surveys, we predict the light curves and spectra of tidal flares as a function of time, highlighting the unique signatures of tidal flares in the optical and near-IR. Some of the gas initially bound to the BH is likely blown away when the fallback rate is super-Eddington at early times. This outflow produces an optical luminosity comparable to that of a supernova; such events have durations of ~10 days and may have been missed in supernova searches that exclude the nuclear regions of galaxies. When the fallback rate subsides below Eddington, the gas accretes onto the BH via a thin disk whose emission peaks in the UV to soft X-rays. Some of this emission is reprocessed by the unbound stellar debris, producing a spectrum of very broad emission lines (with no corresponding narrow forbidden lines). These lines are str...

  19. Rotating Magnetic Structures Associated with a Quasi-circular Ribbon Flare

    Science.gov (United States)

    Li, Haidong; Jiang, Yunchun; Yang, Jiayan; Yang, Bo; Xu, Zhe; Hong, Junchao; Bi, Yi

    2017-02-01

    We present the detection of a small eruption and the associated quasi-circular ribbon flare during the emergence of a bipole occurring on 2015 February 3. Under a fan dome, a sigmoid was rooted in a single magnetic bipole, which was encircled by negative polarity. The nonlinear force-free field extrapolation shows the presence of twisted field lines, which can represent a sigmoid structure. The rotation of the magnetic bipole may cause the twisting of magnetic field lines. An initial brightening appeared at one of the footpoints of the sigmoid, where the positive polarity slides toward a nearby negative polarity field region. The sigmoid displayed an ascending motion and then interacted intensively with the spine-like field. This type of null point reconnection in corona led to a violent blowout jet, and a quasi-circular flare ribbon was also produced. The magnetic emergence and rotational motion are the main contributors to the energy buildup for the flare, while the cancellation and collision might act as a trigger.

  20. Multiwavelength polarimetry and integrated MHD+Polarized Radiation simulation reveal the blazar flaring mechanism

    Science.gov (United States)

    Zhang, Haocheng; Li, Hui; Taylor, Gregory B.

    2017-08-01

    In addition to multiwavelength variability, blazar polarization signatures are highly variable. Optical polarimetry has shown two distinct features: first, in both quiescent and flaring states, blazar polarization degree generally stays around 10% to 30%; second, after major polarization variations, such as polarization angle swings, the polarization degree quickly restores to its initial state. We have performed integrated relativistic magnetohydrodynamic (MHD) + radiation and polarization simulations of the blazar emission region. Our approach evolves the magnetic fields and flows using the first principles, so we can calculate the spatial and temporal dependent polarization signatures and compare them with observations.Our results show that the above two observational trends indicate the blazar flaring region should be strongly magnetized with the magnetic energy density higher than the plasma rest mass energy density. In such an environment, the 3D kink instability may trigger magnetic reconnection to accelerate particles and give rise to flares. In view of future high-energy polarimetry, this integrated MHD+polarization simulation technique will deliver new constraints on jet’s physical conditions and particle acceleration mechanisms.

  1. Coronal type III radio bursts and their X-ray flare and interplanetary type III counterparts

    CERN Document Server

    Reid, Hamish A S

    2016-01-01

    Type III bursts and hard X-rays are both produced by flare energetic electron beams. The link between both emissions has been investigated in many previous studies, but no statistical studies have compared both coronal and interplanetary type III bursts with X-ray flares. Using coronal radio events above 100 MHz exclusively from type III bursts, we revisited long-standing questions: Do all coronal type III bursts have X-ray counterparts. What correlation, if any, occurs between radio and X-ray intensities. What X-ray and radio signatures above 100 MHz occur in connection with interplanetary type III bursts below 14 MHz. We analysed data from 2002 to 2011 starting with coronal type III bursts above 100 MHz. We used RHESSI X-ray data greater than 6 keV to make a list of 321 events that have associated type III bursts and X-ray flares, encompassing at least 28 percent of the initial sample of type III events. We examined the timings, intensities, associated GOES class, and any interplanetary radio signature. For...

  2. Blood compatibility comparison for polysulfone membranes modified by grafting block and random zwitterionic copolymers via surface-initiated ATRP.

    Science.gov (United States)

    Xiang, Tao; Zhang, Li-Sha; Wang, Rui; Xia, Yi; Su, Bai-Hai; Zhao, Chang-Sheng

    2014-10-15

    For blood-contacting materials, good blood compatibility, especially good anticoagulant property is of great importance. Zwitterionic polymers have been proved to be resistant to nonspecific protein adsorption and platelet adhesion; however, their anticoagulant property is always inadequate. In this study, two kinds of zwitterionic copolymers (sulfobetaine methacrylate and sodium p-styrene sulfonate random copolymer and block copolymer) with sulfonic groups were covalently grafted from polysulfone (PSf) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) to improve blood compatibility. Field emission scanning electron microscopy (FE-SEM), attenuated total reflectance-Fourier transform infrared spectra (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and static water contact angle (WCA) were applied to characterize the morphologies, chemical compositions and hydrophilicity of the modified membranes. All the zwitterionic copolymer modified membranes showed improved blood compatibility, especially the anticoagulant property was obviously enhanced compared to the pristine PSf and simple zwitterionic polymer modified membranes. We also found that the random copolymer modified membranes showed better resistance to platelet adhesion than the block copolymer modified membranes. The zwitterionic copolymer modified membranes with integrated antifouling property and blood compatibility provided wide choice for specific applications such as hemodialysis, hemofiltration, and plasma separation.

  3. Comparison between the Methods of Determining the Critical Stress for Initiation of Dynamic Recrystallization in 316 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    M.Jafari; A.Najafizadeh

    2008-01-01

    Several methods have been proposed to calculate the critical stress for initiation of dynamic recrystallization (σc) on the basis of mathematical methods.One of them is proposed by Stewart et al.in which this critical point appears as a distinct minimum in the (-dθ/dσ vs σ) through differentiating from θ vs σ.Another one is presented by Najafizadeh and Jonas by modifying the Poliak and Jonas method.According to this method,the strain hardening rate was plotted against flow stress,and the value of σc was attained numerically from the coefficients of the third-order equation that was the best fit from the experimental θ-σ data.Hot compression tests were used in the range of 1000 to 1100℃ with strain rates of 0.01-1 s-1 and strain of 1 on 316 stainless steel.The result shows that Najafizadeh and Jonas method is simpler than the previous one,and has a good agreement with microstructures.Furthermore,the value of normalized critical stress for this steel was obtained uc=σc/σp=0.92.

  4. The view from K2: questioning the traditional view of flaring on early dM stars

    Science.gov (United States)

    Ramsay, Gavin; Doyle, J. Gerry

    2015-05-01

    We use K2 short cadence data obtained over a duration of 50 d during Campaign 0 to observe two M1V dwarf stars, TYC 1330-879-1 and RXJ 0626+2349. We provide an overview of our data analysis, in particular, making a comparison between using a fixed set of pixels and an aperture which follows the position of the source. We find that this moving aperture approach can give fewer non-astrophysical features compared to a fixed aperture. Both sources shows flares as energetic as observed from several M4V stars using both Kepler and ground-based telescopes. We find that the flare energy distribution of the sources shown here are very similar to the less active M3-M5 stars but are ˜8 times less likely to produce a flare of a comparable energy to the more active M0-M5 stars. We discuss the biases and sources of systematic errors when comparing the activity of stars derived from different instruments. We conclude that K2 observations will provide an excellent opportunity to perform a census of flare activity across the full range of M dwarf spectral class and hence the physical mechanisms which power them.

  5. The view from K2: Questioning the traditional view of flaring on early dM stars

    CERN Document Server

    Ramsay, Gavin

    2015-01-01

    We use K2 short cadence data obtained over a duration of 50 days during Campaign 0 to observe two M1V dwarf stars, TYC 1330-879-1 and RXJ 0626+2349. We provide an overview of our data analysis, in particular, making a comparison between using a fixed set of pixels and an aperture which follows the position of the source. We find that this moving aperture approach can give fewer non-astrophysical features compared to a fixed aperture. Both sources shows flares as energetic as observed from several M4V stars using both Kepler and ground based telescopes. We find that the flare energy distribution of the sources shown here are very similar to the less active M3-M5 stars but are ~8 times less likely to produce a flare of a comparable energy to the more active M0--M5 stars. We discuss the biases and sources of systematic errors when comparing the activity of stars derived from different instruments. We conclude that K2 observations will provide an excellent opportunity to perform a census of flare activity across ...

  6. Solar Magnetic Field Studies Using the 12-Micron Emission Lines. IV. Observations of a Delta-Region Solar Flare

    CERN Document Server

    Jennings, D E; McCabe, G; Sada, P; Moran, T; Jennings, Donald E.; Deming, Drake; Sada, Pedro; Moran, Thomas

    2002-01-01

    We have recently developed the capability to make solar vector (Stokes IQUV) magnetograms using the infrared line of MgI at 12.32 microns. On 24 April 2001, we obtained a vector magnetic map of solar active region NOAA 9433, fortuitously just prior to the occurrence of an M2 flare. Examination of a sequence of SOHO/MDI magnetograms, and comparison with ground-based H-alpha images, shows that the flare was produced by the cancellation of newly emergent magnetic flux outside of the main sunspot. The very high Zeeman-sensitivity of the 12-micron data allowed us to measure field strengths on a spatial scale which was not directly resolvable. At the flare trigger site, opposite polarity fields of 2700 and 1000 Gauss occurred within a single 2 arc-sec resolution element, as revealed by two resolved Zeeman splittings in a single spectrum. Our results imply an extremely high horizontal field strength gradient (5 G/km) prior to the flare, significantly greater than seen in previous studies. We also find that the magne...

  7. The SPARC Data Initiative: comparisons of CFC-11, CFC-12, HF and SF6 climatologies from international satellite limb sounders

    Science.gov (United States)

    Tegtmeier, S.; Hegglin, M. I.; Anderson, J.; Funke, B.; Gille, J.; Jones, A.; Smith, L.; von Clarmann, T.; Walker, K. A.

    2016-02-01

    whole provide guidance on what data sets are the most reliable for applications such as studies of atmospheric transport and variability, model-measurement comparisons and detection of long-term trends. The data sets will be publicly available from the SPARC Data Centre and through PANGAEA (doi:10.1594/PANGAEA.849223).

  8. Modeling Flare Hard X-ray Emission from Electrons in Contracting Magnetic Islands

    Science.gov (United States)

    Guidoni, Silvina E.; Allred, Joel C.; Alaoui, Meriem; Holman, Gordon D.; DeVore, C. Richard; Karpen, Judith T.

    2016-05-01

    The mechanism that accelerates particles to the energies required to produce the observed impulsive hard X-ray emission in solar flares is not well understood. It is generally accepted that this emission is produced by a non-thermal beam of electrons that collides with the ambient ions as the beam propagates from the top of a flare loop to its footpoints. Most current models that investigate this transport assume an injected beam with an initial energy spectrum inferred from observed hard X-ray spectra, usually a power law with a low-energy cutoff. In our previous work (Guidoni et al. 2016), we proposed an analytical method to estimate particle energy gain in contracting, large-scale, 2.5-dimensional magnetic islands, based on a kinetic model by Drake et al. (2010). We applied this method to sunward-moving islands formed high in the corona during fast reconnection in a simulated eruptive flare. The overarching purpose of the present work is to test this proposed acceleration model by estimating the hard X-ray flux resulting from its predicted accelerated-particle distribution functions. To do so, we have coupled our model to a unified computational framework that simulates the propagation of an injected beam as it deposits energy and momentum along its way (Allred et al. 2015). This framework includes the effects of radiative transfer and return currents, necessary to estimate flare emission that can be compared directly to observations. We will present preliminary results of the coupling between these models.

  9. NST and IRIS multi-wavelength observations of an M1.0 class solar flare

    Science.gov (United States)

    Vargas Domínguez, Santiago; Sadykov, Viacheslav; Kosovichev, Alexander; Sharykin, Ivan; Struminsky, Alexei; Zimovets, Ivan

    2015-08-01

    Although solar flares are the most energetic events in the Solar System and have direct impact in the interplanetary space and ultimately in our planet, there are still many unresolved issues concerning their generation, the underlying processes of particle acceleration involved, the effect at different layer in the solar atmosphere, among others. This work presents new coordinated observations from the New Solar Telescope (NST) and the space telescope IRIS that acquired simultaneous observations of an M1.0 class flare occurred on 12 June, 2014 in active region NOAA 12087. NST filtergrams using the TiO filter, together with chromospheric data from the Halpha line allow us to study the evolution of the event from the first signs of the intensification of the intensity in the region. We focused on a small portion where the intensity enhancement in Halpha (blue and red wings) seems to be triggered, and discovered a rapid expansion of a flux-rope structure near the magnetic neutral line, in the sequence of high-resolution photospheric images. IRIS observations evidenced strong emission of the chromospheric and transition region lines during the flare. Jet-like structures are detected before the initiation of the flare in chromospheric lines and strong non-thermal emission in the transition region at the beginning of the impulsive phase. Evaporation flows with velocities up to 50 km/s occurred in the hot chromospheric plasma. We interpreted the result in terms of the “gentle” evaporation that occurs after accelerated particles heat the chromosphere.

  10. Clostridium difficile infection in acute flares of inflammatory bowel disease: A prospective study.

    Science.gov (United States)

    Sokol, Harry; Lalande, Valérie; Landman, Cecilia; Bourrier, Anne; Nion-Larmurier, Isabelle; Rajca, Sylvie; Kirchgesner, Julien; Seksik, Philippe; Cosnes, Jacques; Barbut, Frédéric; Beaugerie, Laurent

    2017-06-01

    Clostridium difficile infection (CDI) is a common complication in inflammatory bowel disease (IBD) and has been associated with poor IBD outcome. The aims of our study were to look for predictive factors of CDI in patients hospitalized for IBD flare and to evaluate a rapid testing strategy in this population. Consecutive patients hospitalized for IBD flare in Saint-Antoine Hospital (Paris, France) were prospectively tested for CDI with a defined strategy involving rapid testing and reference methods. Risk factors for CDI were investigated and performances of diagnostic tests were evaluated. C. difficile testing was performed at admission in 461 hospitalizations for IBD flare. CDI was diagnosed in 35 cases (7.6%) and non-toxigenic C. difficile was identified in 10 cases (2.2%). In multivariate analysis, UC phenotype was associated with CDI (OR 2.2, 95% CI 1.03-4.6, p=0.047). Glutamate dehydrogenase (GDH) test had a 97.1% sensitivity and a 100% negative predictive value for CDI diagnosis but a positive predictive value of 79.1%. Enzyme immunoassay (EIA)-based toxin detection (C. Diff Quik Chek complete(®), Alere) had a poor sensitivity and diagnosis was rescued by toxin PCR in 100% of cases. CDI is frequent in patients hospitalized for IBD flare. Clinical parameters do not help for the diagnosis and rapid testing should be performed in all patients. Currently, a negative result of an EIA-based toxin search associated with a positive GDH test cannot rule out a CDI and should not delay initiation of specific treatment in case of severe symptoms or high presumption. Copyright © 2017 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

  11. Modelling combustion reactions for gas flaring and its resulting emissions

    Directory of Open Access Journals (Sweden)

    O. Saheed Ismail

    2016-07-01

    Full Text Available Flaring of associated petroleum gas is an age long environmental concern which remains unabated. Flaring of gas maybe a very efficient combustion process especially steam/air assisted flare and more economical than utilization in some oil fields. However, it has serious implications for the environment. This study considered different reaction types and operating conditions for gas flaring. Six combustion equations were generated using the mass balance concept with varying air and combustion efficiency. These equations were coded with a computer program using 12 natural gas samples of different chemical composition and origin to predict the pattern of emission species from gas flaring. The effect of key parameters on the emission output is also shown. CO2, CO, NO, NO2 and SO2 are the anticipated non-hydrocarbon emissions of environmental concern. Results show that the quantity and pattern of these chemical species depended on percentage excess/deficiency of stoichiometric air, natural gas type, reaction type, carbon mass content, impurities, combustion efficiency of the flare system etc. These emissions degrade the environment and human life, so knowing the emission types, pattern and flaring conditions that this study predicts is of paramount importance to governments, environmental agencies and the oil and gas industry.

  12. Solar Flare Measurements with STIX and MiSolFA

    CERN Document Server

    Casadei, Diego

    2014-01-01

    Solar flares are the most powerful events in the solar system and the brightest sources of X-rays, often associated with emission of particles reaching the Earth and causing geomagnetic storms, giving problems to communication, airplanes and even black-outs. X-rays emitted by accelerated electrons are the most direct probe of solar flare phenomena. The Micro Solar-Flare Apparatus (MiSolFA) is a proposed compact X-ray detector which will address the two biggest issues in solar flare modeling. Dynamic range limitations prevent simultaneous spectroscopy with a single instrument of all X-ray emitting regions of a flare. In addition, most X-ray observations so far are inconsistent with the high anisotropy predicted by the models usually adopted for solar flares. Operated at the same time as the STIX instrument of the ESA Solar Orbiter mission, at the next solar maximum (2020), they will have the unique opportunity to look at the same flare from two different directions: Solar Orbiter gets very close to the Sun wit...

  13. Risk factors of systemic lupus erythematosus flares during pregnancy.

    Science.gov (United States)

    Jara, Luis J; Medina, Gabriela; Cruz-Dominguez, Pilar; Navarro, Carmen; Vera-Lastra, Olga; Saavedra, Miguel A

    2014-12-01

    This review examines the risk factors for the development of systemic lupus erythematosus (SLE) flares during pregnancy. In preconception, anti-DNA, hypocomplementemia, previous thrombosis, triple antiphospholipid (aPL) antibody positivity, active lupus nephritis and discontinuation of medications such as hydroxychloroquine and azathioprine are factors associated with pregnancy failure. During pregnancy, SLE flares are associated with aPL antibodies, synergic changes of pregnancy on Th1 and TH2 cytokines, other cytokines and chemokines that interact with hormones such as estrogen and prolactin that amplify the inflammatory effect. From the clinical point of view, SLE activity at pregnancy onset, thrombocytopenia, lupus nephritis, arterial hypertension, aPL syndromes, preeclampsia is associated with lupus flares and fetal complications. In puerperium, the risk factors of flares are similar to pregnancy. Hyperactivity of immune system, autoantibodies, hyperprolactinemia, active lupus nephritis, decrease in TH2 cytokines with increase in TH1 cytokines probably participate in SLE flare. The SLE flares during pregnancy make the difference between an uncomplicated pregnancy and pregnancy with maternal and fetal complications. Therefore, the knowledge of risk factors leads the best treatment strategies to reduce flares and fetal complications in SLE patients.

  14. Halpha line profile asymmetries and the chromospheric flare velocity field

    CERN Document Server

    Kuridze, D; Simões, P J A; van der Voort, L Rouppe; Carlsson, M; Jafarzadeh, S; Allred, J C; Kowalski, A F; Kennedy, M; Fletcher, L; Graham, D; Keenan, F P

    2015-01-01

    The asymmetries observed in the line profiles of solar flares can provide important diagnostics of the properties and dynamics of the flaring atmosphere. In this paper the evolution of the Halpha and Ca II 8542 {\\AA} lines are studied using high spatial, temporal and spectral resolution ground-based observations of an M1.1 flare obtained with the Swedish 1-m Solar Telescope. The temporal evolution of the Halpha line profiles from the flare kernel shows excess emission in the red wing (red asymmetry) before flare maximum, and excess in the blue wing (blue asymmetry) after maximum. However, the Ca II 8542 {\\AA} line does not follow the same pattern, showing only a weak red asymmetry during the flare. RADYN simulations are used to synthesise spectral line profiles for the flaring atmosphere, and good agreement is found with the observations. We show that the red asymmetry observed in Halpha is not necessarily associated with plasma downflows, and the blue asymmetry may not be related to plasma upflows. Indeed, w...

  15. Size Distributions of Solar Flares and Solar Energetic Particle Events

    Science.gov (United States)

    Cliver, E. W.; Ling, A. G.; Belov, A.; Yashiro, S.

    2012-01-01

    We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast (much > 1000 km/s) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes (alpha values) of power-law size distributions of the peak 1-8 Angs fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes much > 1 pr/sq cm/s/sr) and (b) fast CMEs were approx 1.3-1.4 compared to approx 1.2 for the peak proton fluxes of >10 MeV SEP events and approx 2 for the peak 1-8 Angs fluxes of all SXR flares. The difference of approx 0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

  16. Dual frequency observations of flares with the VLA

    Science.gov (United States)

    Dulk, G. A.; Bastian, T. S.; Hurford, G. J.

    1983-01-01

    Observations are presented of two subflares near the limb on 21 and 22 November 1981 and an M7.7 flare on 8 May 1981 made at 5 and 15 GHz using the VLA. One of the November flares produced no 5 GHz radiation, while the 15 GHz radiation in the other flare emanated from a source which was smaller, lower, and displaced from the 5 GHz source. The flare occurring on 8 May was intense and complex, and contained two or more sources at both 5 and 15 GHz. Prior to the peak of the flare, the sources were found to grow in size, after which time only weak subsources were visible to the VLA. These subsources were found to be located between or at the edge of the H-alpha ribbons and the two hard X-ray sources imaged by the Hinotori satellite. Highly polarized, bursty radiation was observed at 1 and 2 GHz, which indicated that an electron-cyclotron maser operated during the flare. The maximum field strength in flaring loops is estimated to be 360-600 gauss.

  17. Differential rotation, flares and coronae in A to M stars

    Science.gov (United States)

    Balona, L. A.; Švanda, M.; Karlický, M.

    2016-08-01

    Kepler data are used to investigate flares in stars of all spectral types. There is a strong tendency across all spectral types for the most energetic flares to occur among the most rapidly rotating stars. Differential rotation could conceivably play an important role in enhancing flare energies. This idea was investigated, but no correlation could be found between rotational shear and the incidence of flares. Inspection of Kepler light curves shows that rotational modulation is very common over the whole spectral type range. Using the rotational light amplitude, the size distribution of starspots was investigated. Our analysis suggests that stars with detectable flares have spots significantly larger than non-flare stars, indicating that flare energies are correlated with the size of the active region. Further evidence of the existence of spots on A stars is shown by the correlation between the photometric period and the projected rotational velocity. The existence of spots indicates the presence of magnetic fields, but the fact that A stars lack coronae implies that surface convection is a necessary condition for the formation of the corona.

  18. Soft X-ray Pulsations in Solar Flares

    CERN Document Server

    Simões, Paulo J A; Fletcher, Lyndsay

    2014-01-01

    The soft X-ray emissions of solar flares come mainly from the bright coronal loops at the highest temperatures normally achieved in the flare process. Their ubiquity has led to their use as a standard measure of flare occurrence and energy, although the bulk of the total flare energy goes elsewhere. Recently Dolla et al. (2012) noted quasi-periodic pulsations (QPP) in the soft X-ray signature of the X-class flare SOL2011-02-15, as observed by the standard photometric data from the GOES (Geostationary Operational Environmental Satellite) spacecraft. We analyze the suitability of the GOES data for this kind of analysis and find them to be generally valuable after Sept. 2010 (GOES-15). We then extend Dolla et al. results to a list of X-class flares from Cycle 24, and show that most of them display QPP in the impulsive phase. During the impulsive phase the footpoints of the newly-forming flare loops may also contribute to the observed soft X-ray variations. The QPP show up cleanly in both channels of the GOES dat...

  19. Comparison of Quality Oncology Practice Initiative (QOPI) Measure Adherence Between Oncology Fellows, Advanced Practice Providers, and Attending Physicians.

    Science.gov (United States)

    Zhu, Jason; Zhang, Tian; Shah, Radhika; Kamal, Arif H; Kelley, Michael J

    2015-12-01

    Quality improvement measures are uniformly applied to all oncology providers, regardless of their roles. Little is known about differences in adherence to these measures between oncology fellows, advance practice providers (APP), and attending physicians. We investigated conformance across Quality Oncology Practice Initiative (QOPI) measures for oncology fellows, advance practice providers, and attending physicians at the Durham Veterans Affairs Medical Center (DVAMC). Using data collected from the Spring 2012 and 2013 QOPI cycles, we abstracted charts of patients and separated them based on their primary provider. Descriptive statistics and the chi-square test were calculated for each QOPI measure between fellows, advanced practice providers (APPs), and attending physicians. A total of 169 patients were reviewed. Of these, 31 patients had a fellow, 39 had an APP, and 99 had an attending as their primary oncology provider. Fellows and attending physicians performed similarly on 90 of 94 QOPI metrics. High-performing metrics included several core QOPI measures including documenting consent for chemotherapy, recommending adjuvant chemotherapy when appropriate, and prescribing serotonin antagonists when prescribing emetogenic chemotherapies. Low-performing metrics included documentation of treatment summary and taking action to address problems with emotional well-being by the second office visit. Attendings documented the plan for oral chemotherapy more often (92 vs. 63%, P=0.049). However, after the chart audit, we found that fellows actually documented the plan for oral chemotherapy 88% of the time (p=0.73). APPs and attendings performed similarly on 88 of 90 QOPI measures. The quality of oncology care tends to be similar between attendings and fellows overall; some of the significant differences do not remain significant after a second manual chart review, highlighting that the use of manual data collection for QOPI analysis is an imperfect system, and there may

  20. Comparison of the microstructure, deformation and crack initiation behavior of austenitic stainless steel irradiated in-reactor or with protons

    Energy Technology Data Exchange (ETDEWEB)

    Stephenson, Kale J., E-mail: kalejs@umich.edu; Was, Gary S.

    2015-01-15

    Highlights: • Dislocation loops were the prominent defect, but neutron irradiation caused higher loop density. • Grain boundaries had similar amounts of radiation-induced segregation. • The increment in hardness and yield stress due to irradiation were very similar. • Relative IASCC susceptibility was nearly identical. • The effect of dislocation channel step height on IASCC was similar. - Abstract: The objective of this study was to compare the microstructures, microchemistry, hardening, susceptibility to IASCC initiation, and deformation behavior resulting from proton or reactor irradiation. Two commercial purity and six high purity austenitic stainless steels with various solute element additions were compared. Samples of each alloy were irradiated in the BOR-60 fast reactor at 320 °C to doses between approximately 4 and 12 dpa or by a 3.2 MeV proton beam at 360 °C to a dose of 5.5 dpa. Irradiated microstructures consisted mainly of dislocation loops, which were similar in size but lower in density after proton irradiation. Both irradiation types resulted in the formation of Ni–Si rich precipitates in a high purity alloy with added Si, but several other high purity neutron irradiated alloys showed precipitation that was not observed after proton irradiation, likely due to their higher irradiation dose. Low densities of small voids were observed in several high purity proton irradiated alloys, and even lower densities in neutron irradiated alloys, implying void nucleation was in process. Elemental segregation at grain boundaries was very similar after each irradiation type. Constant extension rate tensile experiments on the alloys in simulated light water reactor environments showed excellent agreement in terms of the relative amounts of intergranular cracking, and an analysis of localized deformation after straining showed a similar response of cracking to surface step height after both irradiation types. Overall, excellent agreement was observed

  1. A national Vascular Quality Initiative database comparison of hybrid and open repair for aortoiliac-femoral occlusive disease.

    Science.gov (United States)

    Zavatta, Marco; Mell, Matthew W

    2017-08-16

    We sought to analyze the outcomes of revascularization for aortoiliac-femoral occlusive disease by comparing hybrid repair by endovascular revascularization and open common femoral endarterectomy (ER-CFE) with open aortoiliac reconstruction and CFE (OR-CFE). Using the national Society for Vascular Surgery Vascular Quality Initiative database from 2009 to 2015, we identified all patients receiving open or endovascular revascularization of the aortoiliac system and who additionally underwent CFE. Patients with concomitant infrainguinal procedures were excluded, as were procedures performed at centers with CFE group and 1472 in the ER-CFE group with follow-up of at least 9 months. Patients with ER-CFE were older (68 ± 9 years vs 63 ± 9 years; P CFE were more likely to have received a previous inflow procedure (27% vs 21%; P CFE (5.2 ± 1.6 vs 2.9 ± 1.0; P CFE was associated with lower 30-day mortality (1.8% vs 3.4%; P = .01), shorter length of stay (median 3 vs 7 days; P CFE had greater ABI improvement at long-term follow-up (0.39 ± 0.37 vs 0.26 ± 0.23; P CFE appeared to have improved short-term outcomes and equivalent freedom from major amputation compared with open surgical repair with CFE. Conversely, open repair with CFE was associated with better long-term improvement in ABI and ambulatory status. Open repair should therefore be considered for patients with aortoiliac-femoral occlusive disease and reasonable surgical risk. Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

  2. Evolution of flare ribbons, electric currents, and quasi-separatrix layers during an X-class flare

    Science.gov (United States)

    Janvier, M.; Savcheva, A.; Pariat, E.; Tassev, S.; Millholland, S.; Bommier, V.; McCauley, P.; McKillop, S.; Dougan, F.

    2016-07-01

    Context. The standard model for eruptive flares has been extended to three dimensions (3D) in the past few years. This model predicts typical J-shaped photospheric footprints of the coronal current layer, forming at similar locations as the quasi-separatrix layers (QSLs). Such a morphology is also found for flare ribbons observed in the extreme ultraviolet (EUV) band, and in nonlinear force-free field (NLFFF) magnetic field extrapolations and models. Aims: We study the evolution of the photospheric traces of the current density and flare ribbons, both obtained with the Solar Dynamics Observatory instruments. We aim to compare their morphology and their time evolution, before and during the flare, with the topological features found in a NLFFF model. Methods: We investigated the photospheric current evolution during the 06 September 2011 X-class flare (SOL2011-09-06T22:20) occurring in NOAA AR 11283 from observational data of the magnetic field obtained with the Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory. We compared this evolution with that of the flare ribbons observed in the EUV filters of the Atmospheric Imager Assembly. We also compared the observed electric current density and the flare ribbon morphology with that of the QSLs computed from the flux rope insertion method-NLFFF model. Results: The NLFFF model shows the presence of a fan-spine configuration of overlying field lines, due to the presence of a parasitic polarity, embedding an elongated flux rope that appears in the observations as two parts of a filament. The QSL signatures of the fan configuration appear as a circular flare ribbon that encircles the J-shaped ribbons related to the filament ejection. The QSLs, evolved via a magnetofrictional method, also show similar morphology and evolution as both the current ribbons and the EUV flare ribbons obtained several times during the flare. Conclusions: For the first time, we propose a combined analysis of the photospheric

  3. Blazar flares powered by plasmoids in relativistic reconnection

    Science.gov (United States)

    Petropoulou, Maria; Giannios, Dimitrios; Sironi, Lorenzo

    2016-11-01

    Powerful flares from blazars with short (˜min) variability time-scales are challenging for current models of blazar emission. Here, we present a physically motivated ab initio model for blazar flares based on the results of recent particle-in-cell (PIC) simulations of relativistic magnetic reconnection. PIC simulations demonstrate that quasi-spherical plasmoids filled with high-energy particles and magnetic fields are a self-consistent by-product of the reconnection process. By coupling our PIC-based results (i.e. plasmoid growth, acceleration profile, particle and magnetic content) with a kinetic equation for the evolution of the electron distribution function we demonstrate that relativistic reconnection in blazar jets can produce powerful flares whose temporal and spectral properties are consistent with the observations. In particular, our model predicts correlated synchrotron and synchrotron self-Compton flares of duration of several hours-days powered by the largest and slowest moving plasmoids that form in the reconnection layer. Smaller and faster plasmoids produce flares of sub-hour duration with higher peak luminosities than those powered by the largest plasmoids. Yet, the observed fluence in both types of flares is similar. Multiple flares with a range of flux-doubling time-scales (minutes to several hours) observed over a longer period of flaring activity (days or longer) may be used as a probe of the reconnection layer's orientation and the jet's magnetization. Our model shows that blazar flares are naturally expected as a result of magnetic reconnection in a magnetically dominated jet.

  4. Comparison of clinical outcomes among users of oral and transdermal estrogen therapy in the Women's Health Initiative Observational Study.

    Science.gov (United States)

    Crandall, Carolyn J; Hovey, Kathleen M; Andrews, Christopher; Cauley, Jane A; Stefanick, Marcia; Shufelt, Chrisandra; Prentice, Ross L; Kaunitz, Andrew M; Eaton, Charles; Wactawski-Wende, Jean; Manson, JoAnn E

    2017-10-01

    To examine associations of estrogen preparations with an index of health risks versus benefits. Using data from 45,112 participants of the Women's Health Initiative Observational Study (average follow-up 5.5 years), we examined associations of estrogen type and oral conjugated equine estrogen (CEE) dose with time to first global index event (GIE), defined as coronary heart disease, breast cancer, stroke, pulmonary embolism, hip fracture, colorectal cancer, endometrial cancer, or death. Oral CEE less than 0.625 mg/d + progestogen (P) users had a lower risk of a GIE (adjusted hazard ratio 0.74, 95% confidence interval 0.56-0.97) than oral CEE 0.625 mg/d + P users. GIE risk in oral CEE 0.625 mg/d + P users was greater with at least 5-year use (adjusted hazard ratio 1.22, 95% confidence interval 1.06-1.41) than with less than 5-year use. In women with prior hysterectomy, compared with women taking oral CEE 0.625 mg/d for less than 5 years, GIE risk was similar with oral CEE below 0.625 mg/d, oral estradiol (E2), and transdermal E2, whether used for less than 5 years or for at least 5 years. There was no difference in GIE risk between users of the following: oral CEE + P versus oral E2 + P; oral CEE + P versus transdermal E2 + P; oral E2 + P versus transdermal E2 + P. Findings were similar among women with hysterectomy taking estrogen alone. The summary index of risks versus benefits was similar for oral CEE versus oral or transdermal E2-containing regimens. CEE + P containing less than 0.625 mg/d of CEE (vs 0.625 mg/d) for less than 5 years appeared safer.

  5. Patient-self assessment of flare in rheumatoid arthritis: translation and reliability of the Flare instrument.

    Science.gov (United States)

    Maribo, Thomas; de Thurah, Annette; Stengaard-Pedersen, Kristian

    2016-04-01

    The Flare instrument (FI) is a French self-administrated questionnaire used to identify flares in disease activity in patients with rheumatoid arthritis. In addition to a total score, the FI has two subscales: one relating to joint symptoms and one relating to general symptoms. The objective of this study was to translate and adapt the French FI into Danish and to determine the reliability of the FI in a consecutive cohort of patients with RA. The FI was translated according to international guidelines, tested among 10 patients and 5 health professionals, and adapted. Test-retest reliability was determined by the standard error of the measurement (SEM) and the intra class correlation coefficients (ICC). The FI was administered to 50 patients with rheumatoid arthritis from an outpatient clinic of a university hospital and re-administered after 10 days. The patients had a mean age of 65.3 years (SD 12.0) and mean disease duration of 18.1 years (range 2-47 years). We found an excellent reliability with ICC higher than 0.95 and SEM between 0.44 and 0.63. Best reliability was found in the total FI score. Thus, the results of the present study show that the FI is a feasible and reliable tool for evaluation of flares in patients with rheumatoid arthritis.

  6. The Giant Flare of 1998 August 27 from SGR 1900+14. I. An Interpretive Study of BeppoSAX and Ulysses Observations

    Science.gov (United States)

    Feroci, M.; Hurley, K.; Duncan, R. C.; Thompson, C.

    2001-03-01

    The giant flare of 1998 August 27 from SGR 1900+14 was extraordinary in many ways: it was the most intense flux of gamma rays ever detected from a source outside our solar system; it was longer than any previously detected burst from a soft gamma repeater (SGR) in our Galaxy by more than an order of magnitude; and it showed a remarkable four-peaked, periodic pattern in hard X-rays with the same rotation period that was found modulating soft X-rays from the star in quiescence. The event was detected by several gamma-ray experiments in space, including the Ulysses gamma-ray burst detector and the BeppoSAX Gamma-Ray Burst Monitor. These instruments operate in different energy ranges, and comparisons of their measurements reveal complex patterns of spectral evolution as the intensity varies. In this paper, we present a joint analysis of the BeppoSAX and Ulysses data and discuss some implications of these results for the SGRs. We also present newly analyzed Venera/SIGNE and ISEE-3 data on the 1979 March 5 giant flare from an SGR in the Large Magellanic Cloud (SGR 0526-66) and compare them with the August 27 event. Our results are consistent with the hypothesis that giant flares are due to catastrophic magnetic instabilities in highly magnetized neutron stars, or ``magnetars.'' In particular, observations indicate that the initial hard spike involved a relativistic outflow of pairs and hard gamma rays, plausibly triggered by a large propagating fracture in the crust of a neutron star with a field exceeding 1014 G. Later stages in the light curve are accurately fitted by a model for emission from the envelope of a magnetically confined pair-photon fireball, anchored to the surface of the rotating star, which contracts as it emits X-rays and then evaporates completely in a finite time. The complex four-peaked shape of the light curve likely provides the most direct evidence known for a multipolar geometry in the magnetic field of a neutron star.

  7. A model for the recurrent flares in EXO 2030 + 375

    Science.gov (United States)

    Taam, Ronald E.; Brown, D. A.; Fryxell, B. A.

    1988-01-01

    It is shown that nonsteady hydrodynamical flows associated with mass and angular momentum capture by a neutron star during a mass ejection phase from a Be star can produce flares with remarkable resemblance to those observed during an outburst from the X-ray transient pulsar EXO 2030 + 375. To reproduce the recurrent time scale of the flares, the velocity of the outflowing matter is estimated to be about 550 km/s. Since the theoretical model requires that a transient disk circulating in one direction is followed by a transient disk circulating in the opposite direction, the time derivative of the pulse period is expected to change sign after each flare event.

  8. Numerical RHD simulations of flaring chromosphere with Flarix

    CERN Document Server

    Heinzel, P; Varady, M; Karlicky, M; Moravec, Z

    2016-01-01

    Flarix is a radiation-hydrodynamical (RHD) code for modeling of the response of the chromosphere to a beam bombardment during solar flares. It solves the set of hydrodynamic conservation equations coupled with non-LTE equations of radiative transfer. The simulations are driven by high energy electron beams. We present results of the Flarix simulations of a flaring loop relevant to the problem of continuum radiation during flares. In particular we focus on properties of the hydrogen Balmer continuum which was recently detected by IRIS.

  9. Systemic lupus erythematosus flare triggered by a spider bite.

    Science.gov (United States)

    Martín Nares, Eduardo; López Iñiguez, Alvaro; Ontiveros Mercado, Heriberto

    2016-01-01

    Systemic lupus erythematosus is a chronic autoimmune disease with a relapsing and remitting course characterized by disease flares. Flares are a major cause of hospitalization, morbidity and mortality in patients with systemic lupus erythematosus. Some triggers for these exacerbations have been identified, including infections, vaccines, pregnancy, environmental factors such as weather, stress and drugs. We report a patient who presented with a lupus flare with predominantly mucocutaneous, serosal and cardiac involvement after being bitten by a spider and we present the possible mechanisms by which the venom elicited such a reaction. To the best of our knowledge, this is the first such case reported in the literature.

  10. Nonlocal thermal transport in solar flares. II - Spectroscopic diagnostics

    Science.gov (United States)

    Karpen, Judith T.; Cheng, Chung-Chieh; Doschek, George A.; Devore, C. Richard

    1989-01-01

    Physical parameters obtained for a flaring solar atmosphere in an earlier paper are used here to predict time-dependent emission-line profiles and integrated intensities as a function of position for two spectral lines commonly observed during solar flares: the X-ray resonance lines of Ca XIX and Mg XI. Considerations of ionization nonequilibrium during the rise phase of the flare are addressed, and the effects on the predicted spectral-line characteristics are discussed. It is concluded that some spectroscopic diagnostics favor the nonlocal model, but other long-standing discrepancies between the numerical models and the observations remain unresolved.

  11. A Review of Flaring and Venting at UK Offshore Oilfields

    OpenAIRE

    Stewart, Jamie R

    2014-01-01

    This study aims to re-address the issue of flaring and venting of reproduced gases in carbon dioxide enhanced oil recovery (CO2EOR) projects. Whilst a number of studies have not recognised the impact of flaring/venting in CO2EOR developments, a study completed at Scottish Carbon Capture and Storage (SCCS) “Carbon Accounting for Carbon Dioxide Enhanced Oil Recovery” highlighted the significant control that flaring/venting of reproduced gases may have on a projects life cycle greenhouse gas emi...

  12. On the triggering of a spotless double-ribbon flare

    Science.gov (United States)

    Rausaria, R. R.; Aleem, S. M.; Sundara Raman, K.

    1992-11-01

    We have studied the evolution of the double-ribbon, spotless flare of 21 February, 1992, using Kodaikanal H-alpha and Kfl observations. The analysis of the data shows that the H-alpha filament underwent a large change in shear prior to the day of the onset of the flare. We find considerable rotation of the plage region before the emergence of a small magnetic pore. It is concluded that shear plays an important role in the triggering of a spotless flare.

  13. Plasma Astrophysics, part II Reconnection and Flares

    CERN Document Server

    Somov, Boris V

    2007-01-01

    This well-illustrated monograph is devoted to classic fundamentals, current practice, and perspectives of modern plasma astrophysics. The first part is unique in covering all the basic principles and practical tools required for understanding and working in plasma astrophysics. The second part presents the physics of magnetic reconnection and flares of electromagnetic origin in space plasmas within the solar system; single and double stars, relativistic objects, accretion disks, and their coronae are also covered. This book is designed mainly for professional researchers in astrophysics. However, it will also be interesting and useful to graduate students in space sciences, geophysics, as well as advanced students in applied physics and mathematics seeking a unified view of plasma physics and fluid mechanics.

  14. On the energy release in solar flares

    CERN Document Server

    Pustil'nik, L A; Beskrovnaya, N G; 10.1063/1.3701351

    2012-01-01

    High-resolution observations show the fine structure of the global equilibrium magnetic field configuration in solar atmosphere to be essentially different from that assumed in the traditional 'potential + force-free' field scenarios. The interacting large-scale structures of fine field elements are separated by numerous non-force-free elements (tangential discontinuities) which are neglected in the traditional field picture. An incorporation of these elements into the model implies a dynamical rather than statical character of equilibrium of the field configuration. A transition of the system into flaring can be triggered by the ballooning mode of flute instability of prominences or/and coronal condensations. Tearing-mode and MHD instabilities as well as the effects of overheating of the turbulent current sheet prevent the field from stationary reconnection as it is adopted in the traditional scenario. We speculate around the assumption that the energy release in active regions is governed by the same scenar...

  15. Modern observations and models of Solar flares

    Science.gov (United States)

    Gritsyk, Pavel; Somov, Boris

    As well known, that fast particles propagating along flare loop generate bremsstrahlung hard x-ray emission and gyro-synchrotron microwave emission. We present the self-consistent kinetic description of propagation accelerated particles. The key point of this approach is taking into account the effect of reverse current. In our two-dimensional model the electric field of reverse current has the strong influence to the beam of accelerated particles. It decelerates part of the electrons in the beam and turns back other part of them without significant energy loss. The exact analytical solution for the appropriate kinetic equation with Landau collision integral was found. Using derived distribution function of electrons we’ve calculated evolution of their energy spectrum and plasma heating, coronal microwave emission and characteristics of hard x-ray emission in the corona and in the chromosphere. All results were compared with modern high precision space observations.

  16. Simultaneous optical and radio observations of flare stars in the Pleiades

    Energy Technology Data Exchange (ETDEWEB)

    Tovmassian, H.M.; Haro, G.; Webber, J.C.; Swenson, G.W. Jr.; Yang, K.S.; Yoss, K.M.; Deming, D.; Green, R.F.

    1974-01-01

    Simultaneous optical (at Tonantzintla, Palomar, and Prairie Observatories) and radio (at the Vermilion River and Owens Valley Radio Observatories) observations of the flare stars in the Pleiades cluster were made from October 1 to 6, 1972. Eleven optical flare-ups were detected. One large flare-up (greater than 8/sup m/ in U) was accompanied by radio flare at 170 MHz. The ratio of optical to radio energy output of this flare is about 6 . 10/sup 2/.

  17. Identifying Preliminary Domains to Detect and Measure Rheumatoid Arthritis Flares: Report of the OMERACT 10 RA Flare Workshop

    DEFF Research Database (Denmark)

    Bingham, Clifton O; Alten, Rieke; Bartlett, Susan J

    2011-01-01

    Background. While disease flares in rheumatoid arthritis (RA) are a recognized aspect of the disease process, there is limited formative research to describe them. METHODS: The Outcome Measures in Rheumatology Clinical Trials (OMERACT) RA Flare Definition Working Group is conducting an internatio......Background. While disease flares in rheumatoid arthritis (RA) are a recognized aspect of the disease process, there is limited formative research to describe them. METHODS: The Outcome Measures in Rheumatology Clinical Trials (OMERACT) RA Flare Definition Working Group is conducting...... an international research project to understand the specific characteristics and impact of episodic disease worsening, or "flare," so that outcome measures can be developed or modified to reflect this uncommonly measured, but very real and sometimes disabling RA disease feature. Patient research partners provided...... was identified as a component of the research agenda needed to establish criterion validity for a flare definition; this can be used in prospective studies to further evaluate the Discrimination and Feasibility components of the OMERACT filter for a flare outcome measure. CONCLUSION: Our work to date has...

  18. The Evaluation and Comparison of Transcriptionally Targeted Noxa and Puma Killer Genes to Initiate Apoptosis Under Cancer-Specific Promoter CXCR1 in Hepatocarcinoma Gene Therapy

    Directory of Open Access Journals (Sweden)

    Khoshtinat Nikkhoi

    2016-09-01

    Full Text Available Background Cancerous cells proliferate as fast as possible without a proper surveillance system. This rapid cell division leads to enormous mutation rates, which help a tumor establish. Objectives This study evaluated the potential of inducing apoptosis using Noxa and Puma in a hepatocarcinoma cell line. Methods The current study generated two recombinant lentiviruses, pLEX-GCN and pLEX-GCP, bearing Noxa and Puma, respectively. Transduction of both genes to hepatocarcinoma (HepG2 was verified using fluorescent microscopic analysis, western blotting, and quantitative real-time polymerase chain reaction (PCR. To evaluate the potential of Noxa and Puma to initiate apoptosis, a caspase-9 real-time, MTT assay, and a 4’, 6-diamidino-2-phenylindole (DAPI reagent were performed to stain apoptotic cells. Results The data verified successful transduction to HepG2 and HEK293T. Higher relative expression of Noxa and Puma rather than the untransduced cell line showed these genes are expressed more in HepG2 in comparison to HEK293T. The results of the real-time PCR, MTT assay, and DAPI reagent illustrated that higher cells initiated apoptosis following Puma transduction rather than Noxa. Conclusions In this approach, the suicide gene was transferred to transformed cells and ignited apoptosis to exterminate them. Puma is a more potent killer gene and has higher capabilities to start intrinsic apoptosis pathway.

  19. Efficacy of I-123/I-131 Metaiodobenzylguanidine Scan as A Single Initial Diagnostic Modality in Pheochromocytoma: Comparison with Biochemical Test and Anatomic Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Eun Ha; Lim, Seok Tae; Jeong, Young Jin; Kim, Dong Wook; Jeong, Hwan Jeong; Sohn, Myung Hee [Chonbuk National University Medical School and Hospital, Jeonju (Korea, Republic of)

    2009-10-15

    We underwent this study to evaluate the diagnostic potential of I-123/I-131 metaiodobenzylguanidine (MIBG) scintigraphy alone in the initial diagnosis of pheochromocytoma, compared with biochemical test and anatomic imaging. Twenty two patients (M:F=13:9, Age: 44.3{+-} 19.3 years) having the clinical evaluation due to suspicious pheochromocytoma received the biochemical test, anatomic imaging modality (CT and/or MRI) and I-123/I-131 MIBG scan for diagnosis of pheochromocytoma, prior to histopathological confirmation. MIBG scans were independently reviewed by 2 nuclear medicine physicians. All patients were confirmed histopathologically by operation or biopsy (incisional or excisonal). In comparison of final diagnosis and findings of each diagnostic modality, the sensitivities of the biochemical test, anatomic imaging, and MIBG scan were 88.9%, 55.6%, and 88.9%, respectively. And the specificities of the biochemical test, anatomic imaging, and MIBG scan also were 69.2%, 69.2%, and 92.3%, respectively. MIBG scan showed one false positive (neuroblastoma) and one false negative finding. There was one patient with positive MIBG scan and negative findings of the biochemical test, anatomic imaging. Our data suggest that I-123/I-131 MIBG scan has higher sensitivity, specificity, positive predictive value, negative predictive value and accuracy than those of biochemical test and anatomic imaging. Thus, we expect that MIBG scan is electively used for initial diagnosis of pheochromocytoma alone as well as biochemical test and anatomic imaging.

  20. A connection between γ-ray and parsec-scale radio flares in the blazar 3C 273

    Science.gov (United States)

    Lisakov, M. M.; Kovalev, Y. Y.; Savolainen, T.; Hovatta, T.; Kutkin, A. M.

    2017-07-01

    We present a comprehensive 5-43 GHz VLBA study of the blazar 3C 273 initiated after an onset of a strong γ-ray flare in this source. We have analysed the kinematics of newborn components, light curves and position of the apparent core to pinpoint the location of the γ-ray emission. Estimated location of the γ-ray emission zone is close to the jet apex, 2-7 pc upstream from the observed 7 mm core. This is supported by ejection of a new component. The apparent core position was found to be inversely proportional to frequency. The brightness temperature in the 7 mm core reached values up to at least 1013 K during the flare. This supports the dominance of particle energy density over that of magnetic field in the 7 mm core. Particle density increased during the radio flare at the apparent jet base, affecting synchrotron opacity. This manifested itself as an apparent core shuttle along the jet during the 7 mm flare. It is also shown that a region where optical depth decreases from τ ˜ 1 to τ ≪ 1 spans over several parsecs along the jet. The jet bulk flow speed estimated at the level of 12c on the basis of time lags between 7 mm light curves of stationary jet features is 1.5 times higher than that derived from very long baseline interferometry apparent kinematics analysis.

  1. Anomalous-plasmoid-ejection-induced secondary magnetic reconnection: modeling solar flares and coronal mass ejections by laser–plasma experiments

    Institute of Scientific and Technical Information of China (English)

    Quanli; Dong; Dawei; Yuan; Shoujun; Wang; Xun; Liu; Yutong; Li; Xiaoxuan; Lin; Huigang; Wei; Jiayong; Zhong; Shaoen; Jiang; Yongkun; Ding; Bobin; Jiang; Kai; Du; Yongjian; Tang; Mingyang; Yu; Xiantu; He; Neng; Hua; Zhanfeng; Qiao; Kuixi; Huang; Ming; Chen; Jianqiang; Zhu; Gang; Zhao; Zhengming; Sheng; Jie; Zhang

    2013-01-01

    The driving mechanism of solar flares and coronal mass ejections is a topic of ongoing debate, apart from the consensus that magnetic reconnection plays a key role during the impulsive process. While present solar research mostly depends on observations and theoretical models, laboratory experiments based on high-energy density facilities provide the third method for quantitatively comparing astrophysical observations and models with data achieved in experimental settings.In this article, we show laboratory modeling of solar flares and coronal mass ejections by constructing the magnetic reconnection system with two mutually approaching laser-produced plasmas circumfused of self-generated megagauss magnetic fields. Due to the Euler similarity between the laboratory and solar plasma systems, the present experiments demonstrate the morphological reproduction of flares and coronal mass ejections in solar observations in a scaled sense,and confirm the theory and model predictions about the current-sheet-born anomalous plasmoid as the initial stage of coronal mass ejections, and the behavior of moving-away plasmoid stretching the primary reconnected field lines into a secondary current sheet conjoined with two bright ridges identified as solar flares.

  2. Observations of a Series of Flares and Associated Jet-like Eruptions Driven by the Emergence of Twisted Magnetic Fields

    CERN Document Server

    Lim, Eun-Kyung; Park, Sung-Hong; Kim, Sujin; Cho, Kyung-Suk; Kumar, Pankaj; Chae, Jongchul; Yang, Heesu; Cho, Kyuhyoun; Song, Donguk; Kim, Yeon-Han

    2015-01-01

    We studied temporal changes of morphological and magnetic properties of a succession of four confined flares followed by an eruptive flare using the high-resolution New Solar Telescope (NST) operating at the Big Bear Solar Observatory (BBSO), Helioseismic and Magnetic Imager (HMI) magnetograms and Atmospheric Image Assembly (AIA) EUV images provided by Solar Dynamics Observatory (SDO). From the NST/Halpha and the SDO/AIA~304 A observations we found that each flare developed a jet structure that evolved in a manner similar to evolution of the blowout jet : 1) an inverted-Y shape jet appeared and drifted away from its initial position; 2) jets formed a curtain-like structure that consisted of many fine threads accompanied with subsequent brightenings near the footpoints of the fine threads; and finally 3) the jet showed a twisted structure visible near the flare maximum. Analysis of the HMI data showed that both the negative magnetic flux and the magnetic helicity have been gradually increasing in the positive ...

  3. Slipping Magnetic Reconnection of Flux Rope Structures as a Precursor to an Eruptive X-class Solar Flare

    CERN Document Server

    Li, Ting; Hou, Yijun; Zhang, Jun

    2016-01-01

    We present the quasi-periodic slipping motion of flux rope structures prior to the onset of an eruptive X-class flare on 2015 March 11, obtained by the \\emph{Interface Region Imaging Spectrograph} (\\emph{IRIS}) and the \\emph{Solar Dynamics Observatory} (\\emph{SDO}). The slipping motion occurred at the north part of the flux rope and seemed to successively peel off the flux rope. The speed of the slippage was 30$-$40 km s$^{-1}$, with an average period of 130$\\pm$30 s. The Si {\\sc iv} 1402.77 {\\AA} line showed a redshift of 10$-$30 km s$^{-1}$ and a line width of 50$-$120 km s$^{-1}$ at the west legs of slipping structures, indicative of reconnection downflow. The slipping motion lasted about 40 min and the flux rope started to rise up slowly at the late stage of the slippage. Then an X2.1 flare was initiated and the flux rope was impulsively accelerated. One of the flare ribbons swept across a negative-polarity sunspot and the penumbral segments of the sunspot decayed rapidly after the flare. We studied the m...

  4. Particle Acceleration by a Solar Flare Termination Shock

    CERN Document Server

    Chen, Bin; Shen, Chengcai; Gary, Dale E; Krucker, Sam; Glesener, Lindsay

    2015-01-01

    Solar flares - the most powerful explosions in the solar system - are also efficient particle accelerators, capable of energizing a large number of charged particles to relativistic speeds. A termination shock is often invoked in the standard model of solar flares as a possible driver for particle acceleration, yet its existence and role have remained controversial. We present observations of a solar flare termination shock and trace its morphology and dynamics using high-cadence radio imaging spectroscopy. We show that a disruption of the shock coincides with an abrupt reduction of the energetic electron population. The observed properties of the shock are well-reproduced by simulations. These results strongly suggest that a termination shock is responsible, at least in part, for accelerating energetic electrons in solar flares.

  5. Powerful flares from recoiling black holes in quasars

    CERN Document Server

    Shields, G A

    2008-01-01

    Mergers of spinning black holes can give recoil velocities from gravitational radiation up to several thousand km/s. A recoiling supermassive black hole in an AGN retains the inner part of its accretion disk. Marginally bound material rejoining the disk around the moving black hole releases a large amount of energy in shocks in a short time, leading to a flare in thermal soft X-rays with a luminosity approaching the Eddington limit. Reprocessing of the X-rays by the infalling material gives strong optical and ultraviolet emission lines with a distinctive spectrum. Despite the short lifetime of the flare (~10^4 yr), as many as 100 flares may be in play at the present time in QSOs at redshifts ~ 1 to 3. These flares provide a means to identify high velocity recoils.

  6. Stellar flares and the dark energy of CMEs

    CERN Document Server

    Drake, Jeremy J; Garraffo, Cecilia; Kashyap, Vinay

    2016-01-01

    Flares we observe on stars in white light, UV or soft X-rays are probably harbingers of coronal mass ejections (CMEs). If we use the Sun as a guide, large stellar flares will dissipate two orders of magnitude less X-ray radiative energy than the kinetic energy in the associated CME. Since coronal emission on active stars appears to be dominated by flare activity, CMEs pose a quandary for understanding the fraction of their energy budget stars can spend on magnetic activity. One answer is magnetic suppression of CMEs, in which the strong large-scale fields of active stars entrap and prevent CMEs unless their free energy exceeds a critical value. The CME-less flaring active region NOAA 2192 presents a possible solar analogue of this. Monster CMEs will still exist, and have the potential to ravage planetary atmospheres.

  7. Gamma-ray flares from the Crab Nebula.

    Science.gov (United States)

    Abdo, A A; Ackermann, M; Ajello, M; Allafort, A; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bouvier, A; Brandt, T J; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Cannon, A; Caraveo, P A; Casandjian, J M; Çelik, Ö; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Costamante, L; Cutini, S; D'Ammando, F; Dermer, C D; de Angelis, A; de Luca, A; de Palma, F; Digel, S W; do Couto e Silva, E; Drell, P S; Drlica-Wagner, A; Dubois, R; Dumora, D; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Fortin, P; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grondin, M-H; Grove, J E; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashi, K; Hayashida, M; Hays, E; Horan, D; Itoh, R; Jóhannesson, G; Johnson, A S; Johnson, T J; Khangulyan, D; Kamae, T; Katagiri, H; Kataoka, J; Kerr, M; Knödlseder, J; Kuss, M; Lande, J; Latronico, L; Lee, S-H; Lemoine-Goumard, M; Longo, F; Loparco, F; Lubrano, P; Madejski, G M; Makeev, A; Marelli, M; Mazziotta, M N; McEnery, J E; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Naumann-Godo, M; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Okumura, A; Omodei, N; Ormes, J F; Ozaki, M; Paneque, D; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Pierbattista, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Ray, P S; Razzano, M; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Romani, R W; Sadrozinski, H F-W; Sanchez, D; Saz Parkinson, P M; Scargle, J D; Schalk, T L; Sgrò, C; Siskind, E J; Smith, P D; Spandre, G; Spinelli, P; Strickman, M S; Suson, D J; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Troja, E; Uchiyama, Y; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Wang, P; Wood, K S; Yang, Z; Ziegler, M

    2011-02-11

    A young and energetic pulsar powers the well-known Crab Nebula. Here, we describe two separate gamma-ray (photon energy greater than 100 mega-electron volts) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The first flare occurred in February 2009 and lasted approximately 16 days. The second flare was detected in September 2010 and lasted approximately 4 days. During these outbursts, the gamma-ray flux from the nebula increased by factors of four and six, respectively. The brevity of the flares implies that the gamma rays were emitted via synchrotron radiation from peta-electron-volt (10(15) electron volts) electrons in a region smaller than 1.4 × 10(-2) parsecs. These are the highest-energy particles that can be associated with a discrete astronomical source, and they pose challenges to particle acceleration theory.

  8. Imaging coronal magnetic-field reconnection in a solar flare

    CERN Document Server

    Su, Yang; Holman, Gordon D; Dennis, Brian R; Wang, Tongjiang; Temmer, Manuela; Gan, Weiqun

    2013-01-01

    Magnetic-field reconnection is believed to play a fundamental role in magnetized plasma systems throughout the Universe1, including planetary magnetospheres, magnetars and accretion disks around black holes. This letter present extreme ultraviolet and X-ray observations of a solar flare showing magnetic reconnection with a level of clarity not previously achieved. The multi-wavelength extreme ultraviolet observations from SDO/AIA show inflowing cool loops and newly formed, outflowing hot loops, as predicted. RHESSI X-ray spectra and images simultaneously show the appearance of plasma heated to >10 MK at the expected locations. These two data sets provide solid visual evidence of magnetic reconnection producing a solar flare, validating the basic physical mechanism of popular flare models. However, new features are also observed that need to be included in reconnection and flare studies, such as three-dimensional non-uniform, non-steady and asymmetric evolution.

  9. Obscuration of Flare Emission by an Eruptive Prominence

    CERN Document Server

    Gopalswamy, Nat

    2013-01-01

    We report on the eclipsing of microwave flare emission by an eruptive prominence from a neighboring region as observed by the Nobeyama Radioheliograph at 17 GHz. The obscuration of the flare emission appears as a dimming feature in the microwave flare light curve. We use the dimming feature to derive the temperature of the prominence and the distribution of heating along the length of the filament. We find that the prominence is heated to a temperature above the quiet Sun temperature at 17 GHz. The duration of the dimming is the time taken by the eruptive prominence in passing over the flaring region. We also find evidence for the obscuration in EUV images obtained by the Solar and Heliospheric Observatory (SOHO) mission.

  10. Flares in Gamma Ray Bursts: Disc Fragmentation and Evolution

    CERN Document Server

    Dall'Osso, Simone; Tanaka, Takamitsu L; Margutti, Raffaella

    2016-01-01

    Flaring activity following gamma-ray bursts (GRBs), observed in both long and short GRBs, signals a long-term activity of the central engine. However, its production mechanism has remained elusive. Here we develop a quantitative model of the idea proposed by Perna et al. of a disc whose outer regions fragment due to the onset of gravitational instability. The self-gravitating clumps migrate through the disc and begin to evolve viscously when tidal and shearing torques break them apart. Our model consists of two ingredients: theoretical bolometric flare lightcurves whose shape (width, skewness) is largely insensitive to the model parameters, and a spectral correction to match the bandpass of the available observations, that is calibrated using the observed spectra of the flares. This simple model reproduces, with excellent agreement, the empirical statistical properties of the flares as measured by their width-to-arrival time ratio and skewness (ratio between decay and rise time). We present model fits to the ...

  11. Driving major solar flares and eruptions: a review

    CERN Document Server

    Schrijver, C J

    2008-01-01

    This review focuses on the processes that energize and trigger major solar flares and flux-rope destabilizations. Numerical modeling of specific solar regions is hampered by uncertain coronal-field reconstructions and by poorly understood magnetic re- connection; these limitations result in uncertain estimates of field topology, energy, and helicity. The primary advances in understanding field destabilizations therefore come from the combination of generic numerical experiments with interpretation of sets of observations. These suggest a critical role for the emergence of twisted flux ropes into pre-existing strong field for many, if not all, of the active regions that pro- duce M- or X-class flares. The flux and internal twist of the emerging ropes appear to play as important a role in determining whether an eruption will develop predom- inantly as flare, confined eruption, or CME, as do the properties of the embedding field. Based on reviewed literature, I outline a scenario for major flares and erup- tions...

  12. Some Properties of Microwave Emission From Flaring Regions

    Institute of Scientific and Technical Information of China (English)

    V. R. Maksimov; V.L. Shchepkina; E.A. Chernova

    2005-01-01

    A study is made of the differences in the polarization distribution and other characteristics of microwave emission for several active regionswith high flare productivity. Conclusions are drawn about the magnetic field structure of these regions at coronal heights.

  13. Evidence That Solar Flares Drive Global Oscillations in the Sun

    Science.gov (United States)

    Karoff, C.; Kjeldsen, H.

    2008-05-01

    Solar flares are large explosions on the Sun's surface caused by a sudden release of magnetic energy. They are known to cause local short-lived oscillations traveling away from the explosion like water rings. Here we show that the energy in the solar acoustic spectrum is correlated with flares. This means that the flares drive global oscillations in the Sun in the same way that the entire Earth is set ringing for several weeks after a major earthquake such as the 2004 December Sumatra-Andaman one. The correlation between flares and energy in the acoustic spectrum of disk-integrated sunlight is stronger for high-frequency waves than for ordinary p-modes which are excited by the turbulence in the near-surface convection zone immediately beneath the photosphere.

  14. Kepler super-flare stars: what are they?

    CERN Document Server

    Wichmann, R; Wolter, U; Nagel, E

    2014-01-01

    The Kepler mission has led to the serendipitous discovery of a significant number of `super flares' - white light flares with energies between 10^33 erg and 10^36 erg - on solar-type stars. It has been speculated that these could be `freak' events that might happen on the Sun, too. We have started a programme to study the nature of the stars on which these super flares have been observed. Here we present high-resolution spectroscopy of 11 of these stars and discuss our results. We find that several of these stars are very young, fast-rotating stars where high levels of stellar activity can be expected, but for some other stars we do not find a straightforward explanation for the occurrence of super flares.

  15. Intralesional triamcinolone for flares of hidradenitis suppurativa (HS)

    DEFF Research Database (Denmark)

    Riis, Peter Theut; Boer, Jurr; Prens, Errol P

    2016-01-01

    BACKGROUND: Hidradenitis suppurativa (HS) is a chronic inflammatory disease of the hair follicle. Standard practice of managing acute flares with corticosteroid injection lacks scientific evidence. OBJECTIVE: We sought to assess the outcomes of routine treatment using intralesional triamcinolone...

  16. Blazar flares powered by plasmoids in relativistic reconnection

    CERN Document Server

    Petropoulou, Maria; Sironi, Lorenzo

    2016-01-01

    Powerful flares from blazars with short ($\\sim$ min) variability timescales are challenging for current models of blazar emission. Here, we present a physically motivated ab initio model for blazar flares based on the results of recent particle-in-cell (PIC) simulations of relativistic magnetic reconnection. PIC simulations demonstrate that quasi-spherical plasmoids filled with high-energy particles and magnetic fields are a self-consistent by-product of the reconnection process. By coupling our PIC-based results (i.e., plasmoid growth, acceleration profile, particle and magnetic content) with a kinetic equation for the evolution of the electron distribution function we demonstrate that relativistic reconnection in blazar jets can produce powerful flares whose temporal and spectral properties are consistent with the observations. In particular, our model predicts correlated synchrotron and synchrotron self-Compton flares of duration of several hours--days powered by the largest and slowest moving plasmoids th...

  17. Gamma-Ray Imager Polarimeter for Solar Flares Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose here to develop the Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS), the next-generation instrument for high-energy solar observations. GRIPS will...

  18. 太阳耀斑的MHD模型%The Magnetohydrodynamic Models of Solar Flares

    Institute of Scientific and Technical Information of China (English)

    吴怡芬

    2011-01-01

    Magnetohydrodynamic(MHD) equations are important models for the fluid's dynamics theory in the plasma.MHD models for the initial stages of solar flares are considered in this paper.%MHD方程组是来解释耀斑的复杂特性的等离子体流体动力学理论的重要模型.为此,主要通过太阳耀斑初期阶段的MHD模型来讨论耀斑的一些特征.

  19. The effects of solar protons flares on the navigation systems of aircraft s and the resulting accents during 20th century

    Science.gov (United States)

    Shaltout, M.; Hady, A.

    In early study for the authors, from the analysis of 802 important accents of the aircraft's which occurred during the period (1920 -2000) all over the world. It is found that the number of occurrence of the accents increases at the solar maximum activity, and decrease with decreasing the solar activity on the annual scale. There is a doubt the geomagnetic storms due to the charged particles, which come from the s un as a cloud after two or three days from the high energetic flares occurrence. Which affected on the navigation system of the aircraft's, especially for aircraft's which pass through the polar regions of the earth, at the high latitudes. The aim of the present study is to analysis more than one handed solar protons flares (1970-2000) of energies more than 10 MeV observed by the artificial satellite! GOES and published in solar Geophysical Data, NOAA, Boulder, Colorado, USA. A comparison studies between the proton flares occurrence and the important accents of the aircraft's, which occur after two days to one week, from the high energetic proton flares occurrence, or case by case, in an attempt to confirm the relation between the solar activities and aircraft accents due to disturbance in the Navigation systems. Also, we not Ignore in our study the effects of the geomagnetic field on the flying staff, due to the occurrence of the solar proton flares, as indicated by other authors in early studies.

  20. Electron and proton kinetics and dynamics in flaring atmospheres

    CERN Document Server

    Zharkova, Valentina

    2012-01-01

    This timely book presents new research results on high-energy particle physics related to solar flares, covering the theory and applications of the reconnection process in a clear and comprehensible way. It investigates particle kinetics and dynamics in flaring atmospheres and their diagnostics from spectral observations, while providing an analysis of the observation data and techniques and comparing various models. Written by an internationally acclaimed expert, this is vital reading for all solar, astro-, and plasma physicists working in the field.

  1. Temporal variations of the Venus ionosphere during solar flares

    Science.gov (United States)

    Uesugi, A.; Fujiwara, H.; Fukunishi, H.

    2006-12-01

    The effects of long-term solar activity changes such as 11-year cycle and 27-day cycle on the Venus ionosphere have been investigated by a number of researchers using data obtained from some spacecrafts. However, the effects of short-term solar activity changes, particularly the effect of solar flares, are still unknown because there are no simultaneous observations of the Venus ionosphere and solar flares. The past observations of the Earth's ionosphere suggest significant and instantaneous changes of the Venus ionosphere during solar flares. Recently, Mars Global Surveyor (MGS) revealed the temporal variations of the Mars ionosphere during solar flares. The electron density of the Mars ionosphere was enhanced by ~10% at the main peak and 200% at the secondary peak at that time. The recent satellite observations of the solar X- rays enable us to model the Earth's and planetary ionospheres more exactly. In order to investigate the temporal variations of the Venus ionosphere during solar flares, we have developed a 1-D photochemical model for estimating vertical profiles of ions and electrons. We have also modeled temporal variations of solar flare using the EUV/X-rays data obtained by TIMED/SEE (0.1-194 nm) and GOES (0.1-0.8 nm) on October 28, 2003. Using the photochemical and solar flare models, we have calculated temporal variations of ion composition in the dayside Venus ionosphere. In addition, time constants for production and loss of ionospheric compositions through the photochemical reactions can be examined. We discuss differences of the response to solar flare among three planets, Venus, Earth and Mars. Then, the characteristics of the Venus ionosphere will be clarified.

  2. "Magnetar Hyper-Flares: Whole Lotta Shakin' Goin' on"

    Science.gov (United States)

    Strohmayer, Tod

    2008-01-01

    The giant flares produced by highly magnetized neutron stars, "magnetars," are the brightest sources of high energy radiation outside our solar system. High frequency oscillations have been discovered during portions of the two most recently observed giant flares which may represent the first detection of global oscillation modes of neutron stars. I will give an observational and theoretical overview of these oscillations and describe how they might allow us to probe neutron star interiors and dense matter physics.

  3. Fast X-Ray Oscillations during Magnetar Flares

    Science.gov (United States)

    Strohmayer Tod E.

    2009-01-01

    The giant flares produced by highly magnetized neutron stars, "magnetars," are the brightest sources of high energy radiation outside our solar system. High frequency oscillations have been discovered during portions of the two most recently observed giant flares which may represent the first detection of global oscillation modes of neutron stars. I will give an observational and theoretical overview of these oscillations and describe how they might allow us to probe neutron star interiors and dense matter physics.

  4. Multifrequency Behaviour of the Gamma-Ray Binary System PSR B1259-63: Modelling the FERMI Flare

    Directory of Open Access Journals (Sweden)

    Brian van Soelen

    2014-12-01

    Full Text Available This paper presents a brief overview of the multifrequency properties of the gamma-ray binary system PSR B1259-63 from radio to very high energy gamma-rays. A summary is also presented of the various models put forward to explain the Fermi "flare" detected in 2011. Initial results are presented of a new turbulence driven model to explain the GeV observations.

  5. Flares in gamma-ray bursts: disc fragmentation and evolution

    Science.gov (United States)

    Dall'Osso, Simone; Perna, Rosalba; Tanaka, Takamitsu L.; Margutti, Raffaella

    2017-02-01

    Flaring activity following gamma-ray bursts (GRBs), observed in both long and short GRBs, signals a long-term activity of the central engine. However, its production mechanism has remained elusive. Here, we develop a quantitative model of the idea proposed by Perna et al. of a disc whose outer regions fragment due to the onset of gravitational instability. The self-gravitating clumps migrate through the disc and begin to evolve viscously when tidal and shearing torques break them apart. Our model consists of two ingredients: theoretical bolometric flare light curves whose shape (width, skewness) is largely insensitive to the model parameters, and a spectral correction to match the bandpass of the available observations, that is calibrated using the observed spectra of the flares. This simple model reproduces, with excellent agreement, the empirical statistical properties of the flares as measured by their width-to-arrival time ratio and skewness (ratio between decay and rise time). We present model fits to the observed light curves of two well-monitored flares, GRB 060418 and GRB 060904B. To the best of our knowledge, this is the first quantitative model able to reproduce the flare light curves and explain their global statistical properties.

  6. JITTER RADIATION MODEL OF THE CRAB GAMMA-RAY FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Teraki, Yuto; Takahara, Fumio, E-mail: teraki@vega.ess.sci.osaka-u.ac.jp [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan)

    2013-02-15

    The gamma-ray flares of the Crab nebula detected by the Fermi and AGILE satellites challenge our understanding of the physics of pulsars and their nebulae. The central problem is that the peak energy of the flares exceeds the maximum energy E {sub c} determined by synchrotron radiation loss. However, when turbulent magnetic fields exist with scales {lambda}{sub B} smaller than 2{pi}mc {sup 2}/eB, jitter radiation can emit photons with energies higher than E {sub c}. The scale required for the Crab flares is about two orders of magnitude less than the wavelength of the striped wind. We discuss a model in which the flares are triggered by plunging the high-density blobs into the termination shock. The observed hard spectral shape may be explained by the jitter mechanism. We make three observational predictions: first, the polarization degree will become lower in flares; second, no counterpart will be seen in TeV-PeV range; and third, the flare spectrum will not be harder than {nu}F {sub {nu}}{proportional_to}{nu}{sup 1}.

  7. Constraining Solar Flare Differential Emission Measures with EVE and RHESSI

    CERN Document Server

    Caspi, Amir; Warren, Harry P

    2014-01-01

    Deriving a well-constrained differential emission measure (DEM) distribution for solar flares has historically been difficult, primarily because no single instrument is sensitive to the full range of coronal temperatures observed in flares, from $\\lesssim$2 to $\\gtrsim$50 MK. We present a new technique, combining extreme ultraviolet (EUV) spectra from the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory with X-ray spectra from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), to derive, for the first time, a self-consistent, well-constrained DEM for jointly-observed solar flares. EVE is sensitive to ~2-25 MK thermal plasma emission, and RHESSI to $\\gtrsim$10 MK; together, the two instruments cover the full range of flare coronal plasma temperatures. We have validated the new technique on artificial test data, and apply it to two X-class flares from solar cycle 24 to determine the flare DEM and its temporal evolution; the constraints on the thermal emission derived from ...

  8. Multi-Thread Hydrodynamic Modeling of a Solar Flare

    CERN Document Server

    Warren, H P

    2006-01-01

    Past hydrodynamic simulations have been able to reproduce the high temperatures and densities characteristic of solar flares. These simulations, however, have not been able to account for the slow decay of the observed flare emission or the absence of blueshifts in high spectral resolution line profiles. Recent work has suggested that modeling a flare as an sequence of independently heated threads instead of as a single loop may resolve the discrepancies between the simulations and observations. In this paper we present a method for computing multi-thread, time-dependent hydrodynamic simulations of solar flares and apply it to observations of the Masuda flare of 1992 January 13. We show that it is possible to reproduce the temporal evolution of high temperature thermal flare plasma observed with the instruments on the \\textit{GOES} and \\textit{Yohkoh} satellites. The results from these simulations suggest that the heating time-scale for a individual thread is on the order of 200 s. Significantly shorter heati...

  9. Perception on Effect of Gas Flaring on the Environment

    Directory of Open Access Journals (Sweden)

    Ayanlade Ayansina

    2010-10-01

    Full Text Available The study assessed the adverse effect of gas flaring on the environment and the potential benefits of its reduction on the local economy and the environment at large. This was with a view to suggesting an integrated strategy and management plan for sustainable environment in the gas flaring areas. The study used both primary and secondary data. The primary data was obtained through administration of two hundred and ten questionnaires which focused mainly on the impact of gas flaring on farm activities; adaptation to gas flaring effects; farmers perception on gas flaring and climate change and crop performance; etc. coupled with intensive fieldwork. The data w ere presented in form of tables showing frequencies and percentages. Secondary data used were those of monthly rainfall totals between 1992 and 2002, obtained from the meteorological station of the Qua Iboe Terminus (QIT. The method of trend fittings was used in analyzing the data. The result of the study clearly shows that gas flaring has contributed significantly to environmental degradation in the area.

  10. X-ray flaring from Sagittarius A*: exploring the Milky Way black hole through its brightest flares

    Science.gov (United States)

    Nynka, Melania; Haggard, Daryl

    2017-08-01

    Sagittarius A* is the supermassive black hole at the center of our own Milky Way galaxy. Ambitious monitoring campaigns have yielded rich multiwavelength, time-resolved data, which have the power to probe the physical processes that underlie Sgr A*'s quiescent and flare emission. In 2013 and 2014 the Chandra X-ray Observatory captured two extremely luminous flares from Sgr A*, the two brightest ever detected in X-ray. I will describe the spectral and temporal properties of these flares, how they compare to previous analysis, and the possible physical processes driving the Sgr A* variability. I will also discuss the power spectral densities of the flares which may contain information about the black hole's ISCO and spin.

  11. ON THE POLARIZATION PROPERTIES OF MAGNETAR GIANT FLARE PULSATING TAILS

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yuan-Pei [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Zhang, Bing, E-mail: yypspore@gmail.com, E-mail: zhang@physics.unlv.edu [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States)

    2015-12-10

    Three giant flares have been detected so far from soft gamma-ray repeaters, each characterized by an initial short hard spike and a pulsating tail. The observed pulsating tails are characterized by a duration of ∼100 s, an isotropic energy of ∼10{sup 44} erg, and a pulse period of a few seconds. The pulsating tail emission likely originates from the residual energy after the intense energy release during the initial spike, which forms a trapped fireball composed of a photon-pair plasma in a closed-field-line region of the magnetars. Observationally the spectra of pulsating tails can be fitted by the superposition of a thermal component and a power-law component, with the thermal component dominating the emission in the early and late stages of the pulsating-tail observations. In this paper, assuming that the trapped fireball is from a closed-field-line region in the magnetosphere, we calculate the atmospheric structure of the optically thick trapped fireball and the polarization properties of the trapped fireball. By properly treating the photon propagation in a hot, highly magnetized, electron–positron pair plasma, we tally photons in two modes (O mode and E mode) at a certain observational angle through Monte Carlo simulations. Our results suggest that the polarization degree depends on the viewing angle with respect to the magnetic axis of the magnetar, and can be as high as Π ≃ 30% in the 1–30 keV band, and Π ≃ 10% in the 30–100 keV band, if the line of sight is perpendicular to the magnetic axis.

  12. Statistical Models for Solar Flare Interval Distribution in Individual Active Regions

    CERN Document Server

    Kubo, Yuki

    2008-01-01

    This article discusses statistical models for solar flare interval distribution in individual active regions. We analyzed solar flare data in 55 active regions that are listed in the GOES soft X-ray flare catalog. We discuss some problems with a conventional procedure to derive probability density functions from any data set and propose a new procedure, which uses the maximum likelihood method and Akaike Information Criterion (AIC) to objectively compare some competing probability density functions. We found that lognormal and inverse Gaussian models are more likely models than the exponential model for solar flare interval distribution in individual active regions. The results suggest that solar flares do not occur randomly in time; rather, solar flare intervals appear to be regulated by solar flare mechanisms. We briefly mention a probabilistic solar flare forecasting method as an application of a solar flare interval distribution analysis.

  13. Oilfield Flare Gas Electricity Systems (OFFGASES Project)

    Energy Technology Data Exchange (ETDEWEB)

    Rachel Henderson; Robert Fickes

    2007-12-31

    The Oilfield Flare Gas Electricity Systems (OFFGASES) project was developed in response to a cooperative agreement offering by the U.S. Department of Energy (DOE) and the National Energy Technology Laboratory (NETL) under Preferred Upstream Management Projects (PUMP III). Project partners included the Interstate Oil and Gas Compact Commission (IOGCC) as lead agency working with the California Energy Commission (CEC) and the California Oil Producers Electric Cooperative (COPE). The project was designed to demonstrate that the entire range of oilfield 'stranded gases' (gas production that can not be delivered to a commercial market because it is poor quality, or the quantity is too small to be economically sold, or there are no pipeline facilities to transport it to market) can be cost-effectively harnessed to make electricity. The utilization of existing, proven distribution generation (DG) technologies to generate electricity was field-tested successfully at four marginal well sites, selected to cover a variety of potential scenarios: high Btu, medium Btu, ultra-low Btu gas, as well as a 'harsh', or high contaminant, gas. Two of the four sites for the OFFGASES project were idle wells that were shut in because of a lack of viable solutions for the stranded noncommercial gas that they produced. Converting stranded gas to useable electrical energy eliminates a waste stream that has potential negative environmental impacts to the oil production operation. The electricity produced will offset that which normally would be purchased from an electric utility, potentially lowering operating costs and extending the economic life of the oil wells. Of the piloted sites, the most promising technologies to handle the range were microturbines that have very low emissions. One recently developed product, the Flex-Microturbine, has the potential to handle the entire range of oilfield gases. It is deployed at an oilfield near Santa Barbara to run on waste gas

  14. A Database of Flare Ribbon Properties From Solar Dynamics Observatory: Reconnection Flux

    Science.gov (United States)

    Kazachenko, Maria D.; Welsch, Brian; Lynch, Benjamin J.; Sun, Xudong

    2017-08-01

    We present a database of 3137 solar flare ribbon events corresponding to every flare of GOES class C1.0 and greater within 45 degrees from the disk center, from April 2010 until April 2016, observed by the Solar Dynamics Observatory. For every event in the database, we compare the GOES peak X-ray flux with corresponding active-region and flare-ribbon properties. We find that while the peak X-ray flux is not correlated with the AR unsigned magnetic flux, it is strongly correlated with the flare ribbon reconnection flux, flare ribbon area, and the fraction of active region flux that undergoes reconnection. We find the relationship between the peak X-ray flux and the flare ribbon reconnection flux to be I_{X,peak} ~ \\Phi_{ribbon}^{1.3} for flares >M1 and I_{X,peak} ~ \\Phi_{ribbon}^{1.5} over the entire flare set (>C1). This scaling law is consistent with earlier hydrodynamic simulations of impulsively heated flare loops. Using the flare reconnection flux as a proxy for the total released flare energy E, we find that the occurrence frequency of flare energies follows a power-law dependence: dN/dE ~ E^{-1.6} for E within 10^{31} to 10^{33} erg, consistent with earlier studies of solar and stellar flares. This database is available online and can be used for future quantitative studies of flares.

  15. Ultraviolet Spectroscopy of Tidal Disruption Flares

    Science.gov (United States)

    Cenko, Stephen B.

    2017-08-01

    When a star passes within the sphere of disruption of a massive black hole, tidal forces will overcome self-gravity and unbind the star. While approximately half of the stellar debris is ejected at high velocities, the remaining material stays bound to the black hole and accretes, resulting in a luminous, long-lived transient known as a tidal disruption flare (TDF). In addition to serving as unique laboratories for accretion physics,TDFs offer the hope of measuring black hole masses in galaxies much too distant for resolved kinematic studies.In order to realize this potential, we must better understand the detailed processes by which the bound debris circularizes and forms an accretion disk. Spectroscopy is critical to this effort, as emission and absorption line diagnostics provide insight into the location and physical state (velocity, density, composition) of the emitting gas (in analogy with quasars). UV spectra are particularly critical, as most strong atomic features fall in this bandpass, and high-redshift TDF discoveries from LSST will sample rest-frame UV wavelengths.Here I present recent attempts to obtain UV spectra of tidal disruption flares. I describe the UV spectrum of ASASSN-14li, in which we detect three classes of features: narrow absorption from the Milky Way (probably a high-velocity cloud), and narrow absorption and broad (2000-8000 km s-1) emission lines at or near the systemic host velocity. The absorption lines are blueshifted with respect to the emission lines by 250-400 km s-1. Due both to this velocity offset and the lack of common low-ionization features (Mg II, Fe II), we argue these arise from the same absorbing material responsible for the low-velocity outflow discovered at X-ray wavelengths. The broad nuclear emission lines display a remarkable abundance pattern: N III], N IV], and He II are quite prominent, while the common quasar emission lines of C III] and Mg II are weak or entirely absent. Detailed modeling of this spectrum will

  16. Evolution of Flare Ribbons, Electric Currents and Quasi-separatrix Layers During an X-class Flare

    CERN Document Server

    Janvier, M; Pariat, E; Tassev, S; Millholland, S; Bommier, V; McCauley, P; McKillop, S; Dougan, F

    2016-01-01

    The standard model for eruptive flares has in the past few years been extended to 3D. It predicts typical J-shaped photospheric footprints of the coronal current layer, forming at similar locations as the Quasi-Separatrix Layers (QSLs). Such a morphology is also found for flare ribbons observed in the EUV band, as well as in non-linear force-free field (NLFFF) magnetic field extrapolations and models. We study the evolution of the photospheric traces of the current density and flare ribbons, both obtained with the SDO instruments. We investigate the photospheric current evolution during the 6 September 2011 X-class flare (SOL2011-09-06T22:20) from observational data of the magnetic field obtained with HMI. This evolution is compared with that of the flare ribbons observed in the EUV filters of the AIA. We also compare the observed electric current density and the flare ribbon morphology with that of the QSLs computed from the flux rope insertion method/NLFFF model. The NLFFF model shows the presence of a fan-...

  17. Flare Prediction Using Photospheric and Coronal Image Data

    Science.gov (United States)

    Jonas, E.; Shankar, V.; Bobra, M.; Recht, B.

    2016-12-01

    We attempt to forecast M-and X-class solar flares using a machine-learning algorithm and five years of image data from both the Helioseismic and Magnetic Imager (HMI) and Atmospheric Imaging Assembly (AIA) instruments aboard the Solar Dynamics Observatory. HMI is the first instrument to continuously map the full-disk photospheric vector magnetic field from space (Schou et al., 2012). The AIA instrument maps the transition region and corona using various ultraviolet wavelengths (Lemen et al., 2012). HMI and AIA data are taken nearly simultaneously, providing an opportunity to study the entire solar atmosphere at a rapid cadence. Most flare forecasting efforts described in the literature use some parameterization of solar data - typically of the photospheric magnetic field within active regions. These numbers are considered to capture the information in any given image relevant to predicting solar flares. In our approach, we use HMI and AIA images of solar active regions and a deep convolutional kernel network to predict solar flares. This is effectively a series of shallow-but-wide random convolutional neural networks stacked and then trained with a large-scale block-weighted least squares solver. This algorithm automatically determines which patterns in the image data are most correlated with flaring activity and then uses these patterns to predict solar flares. Using the recently-developed KeystoneML machine learning framework, we construct a pipeline to process millions of images in a few hours on commodity cloud computing infrastructure. This is the first time vector magnetic field images have been combined with coronal imagery to forecast solar flares. This is also the first time such a large dataset of solar images, some 8.5 terabytes of images that together capture over 3000 active regions, has been used to forecast solar flares. We evaluate our method using various flare prediction windows defined in the literature (e.g. Ahmed et al., 2013) and a novel per

  18. Automatic prediction of solar flares and super geomagnetic storms

    Science.gov (United States)

    Song, Hui

    Space weather is the response of our space environment to the constantly changing Sun. As the new technology advances, mankind has become more and more dependent on space system, satellite-based services. A geomagnetic storm, a disturbance in Earth's magnetosphere, may produce many harmful effects on Earth. Solar flares and Coronal Mass Ejections (CMEs) are believed to be the major causes of geomagnetic storms. Thus, establishing a real time forecasting method for them is very important in space weather study. The topics covered in this dissertation are: the relationship between magnetic gradient and magnetic shear of solar active regions; the relationship between solar flare index and magnetic features of solar active regions; based on these relationships a statistical ordinal logistic regression model is developed to predict the probability of solar flare occurrences in the next 24 hours; and finally the relationship between magnetic structures of CME source regions and geomagnetic storms, in particular, the super storms when the D st index decreases below -200 nT is studied and proved to be able to predict those super storms. The results are briefly summarized as follows: (1) There is a significant correlation between magnetic gradient and magnetic shear of active region. Furthermore, compared with magnetic shear, magnetic gradient might be a better proxy to locate where a large flare occurs. It appears to be more accurate in identification of sources of X-class flares than M-class flares; (2) Flare index, defined by weighting the SXR flares, is proved to have positive correlation with three magnetic features of active region; (3) A statistical ordinal logistic regression model is proposed for solar flare prediction. The results are much better than those data published in the NASA/SDAC service, and comparable to the data provided by the NOAA/SEC complicated expert system. To our knowledge, this is the first time that logistic regression model has been applied

  19. Coronary angiography findings in cardiac arrest patients with non-diagnostic post-resuscitation electrocardiogram: A comparison of shockable and non-shockable initial rhythms.

    Science.gov (United States)

    Martínez-Losas, Pedro; Salinas, Pablo; Ferrera, Carlos; Nogales-Romo, María Teresa; Noriega, Francisco; Del Trigo, María; Núñez-Gil, Iván Javier; Nombela-Franco, Luis; Gonzalo, Nieves; Jiménez-Quevedo, Pilar; Escaned, Javier; Fernández-Ortiz, Antonio; Macaya, Carlos; Viana-Tejedor, Ana

    2017-08-26

    To investigate the impact of coronary artery disease in a cohort of patients resuscitated from cardiac arrest with non-diagnostic electrocardiogram. From March 2004 to February 2016, 203 consecutive patients resuscitated from in or out-of-hospital sudden cardiac arrest and non-diagnostic post-resuscitation electrocardiogram (defined as ST segment elevation or pre-sumably new left bundle branch block) who underwent invasive coronary angiogram during hospitalization were included. For purpose of analysis and comparison, patients were classified in two groups: Initial shockable rhythm (ventricular tachycardia or ventricular fibrillation; n = 148, 72.9%) and initial non-shockable rhythm (n = 55, 27.1%). Baseline characteristics, coronary angiogram findings including Syntax Score and long-term survival rates were compared. Sudden cardiac arrest was witnessed in 95.2% of cases, 66.7% were out-of-hospital patients and 72.4% were male. There were no significant differences in baseline characteristics between groups except for higher mean age (68.1 years vs 61 years, P = 0.001) in the non-shockable rhythm group. Overall 5-year mortality of the resuscitated patients was 37.4%. Patients with non-shockable rhythms had higher mortality (60% vs 29.1%, P < 0.001) and a worst neurological status at hospital discharge based on cerebral performance category score (CPC 1-2: 32.7% vs 53.4%, P = 0.02). Although there were no significant differences in global burden of coronary artery disease defined by Syntax Score (mean Syntax Score: 10.2 vs 10.3, P = 0.96) there was a trend towards a higher incidence of acute coronary lesions in patients with shockable rhythm (29.7% vs 16.4%, P = 0.054). There was also a higher need for ad-hoc percutaneous coronary intervention in this group (21.9% vs 9.1%, P = 0.03). Initial shockable group of patients had a trend towards higher incidence of acute coronary lesions and higher need of ad-hoc percutaneous intervention vs non-shockable group.

  20. Flare in spondyloarthritis: Thresholds of disease activity variations.

    Science.gov (United States)

    Godfrin-Valnet, Marie; Puyraveau, Marc; Prati, Clément; Wendling, Daniel

    2015-05-01

    There is no definition of flare in spondyloarthritis (SpA). The aim of this study was to evaluate thresholds of disease activity variations using validated composite indexes. SpA patients (ASAS criteria) prospectively followed with at least two visits, were evaluated. Patients and physician answered at each visit the question: "do you consider your SpA/patient in a state of flare?". Variations of BASDAI and ASDAS between visits were assessed and associated to the change of perception of a flare (yes/no). ROC curves were built to assess thresholds of variation in BASDAI and ASDAS associated with the change flare between visits. The patients were issued from a prospective series of 250 SpA. Ninety-nine cases with at least 2 visits were analysed. They were: 67% men, mean age 45±12 years; disease duration: 16±10 years; 84% HLA-B27 positive; purely axial SpA: 81%; PASS at baseline: 56%; mean CRP: 8.6±13.5mg/l. Mean BASDAI and ASDAS-CRP at baseline were 4.3±2.2 and 2.5±1.1, respectively. The kappa coefficient of agreement between patient and physician for considering a flare was 0.68. The main results of the ROC curves are: a variation ≥2.1 units in BASDAI (sensitivity 59%, specificity 83%), 0.8 units in ASDAS-ESR (sen 56%, spe 91%) or 1.3 units in ASDAS-CRP (sen 47%, spe 100%) is associated to a flare. We propose thresholds of variations of BASDAI, ASDAS-ESR, and ASDAS-CRP associated to (and that may define) a flare, as considered by the patient and the physician. Copyright © 2015 Société française de rhumatologie. Published by Elsevier SAS. All rights reserved.